Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/20/14
AREA FORECAST DISCUSSION
NWS LITTLE ROCK AR
1246 PM CDT MON AUG 18 2014
.AVIATION...
A STATIONARY FRONT REMAINS ACROSS NORTH ARKANSAS TODAY.
THUNDERSTORMS HAVE EXITIED SOUTHEAST ARKANSAS AND HAVE DEVELOPED
IN NORTHEAST OKLAHOMA. THE STORMS IN NORTHEAST OKLAHOMA SHOULD
MISS THE TAF SITES. ISOLATED THUNDERSTORMS COULD DEVELOP THIS
AFTERNOON HOWEVER. SOME LOW CLOUDS WILL LINGER IN CENTRAL AND
SOUTH SECTIONS FOR A COUPLE OF HOURS. BROKEN CUMULUS ARE EXPECTED
FOR THE REST OF THE AFTERNOON. PATCHY FOG IS LIKELY IN THE MORNING
ESPECIALLY IN CENTRAL AND SOUTH SECTIONS. AFTER SOME IFR
CONDITIONS EARLY THIS AFTERNOON...EXPECT VFR TO MVFR THE REST OF
THE PERIOD.
&&
.PREV DISCUSSION... /ISSUED 1109 AM CDT MON AUG 18 2014/
UPDATE...
CONVECTION STARTING TO CLEAR OUT IN THE SE PART OF THE CWA AND
HAS LEFT A POOL OF RAIN COOLED TEMPERATURES IN ITS WAKE. MAKING
ADJUSTMENTS TO MAX TEMPERATURES TODAY BASED ON THIS...AND ALSO
MAKING TWEAKS TO POPS...DEW POINTS...AND CLOUD COVER BASED ON
CURRENT SYNOPTIC SITUATION.
HRR AND RUC MODELS FORECASTING REDEVELOPMENT OF CONVECTION THIS
AFTERNOON ACROSS PORTIONS OF NORTH CENTRAL AND CENTRAL ARKANSAS. 53
PREV DISCUSSION... /ISSUED 647 AM CDT MON AUG 18 2014/
AVIATION...18/12Z TAF CYCLE
AREA OF SHRA/TSRA...ASSOCD WITH AN MCV...WL CONT TO TRACK EWD ACRS
CNTRL AND SRN AR THIS MRNG. WIDESPREAD MVFR/IFR CONDS CAN BE
EXPECTED WITH THIS ACTIVITY. CANNOT RULE OUT SOME WDLY SCTD
CONVECTION ACRS THE AREA THIS AFTN. OTHERWISE...VFR CONDS WL
PREVAIL. THERE IS THE POTENTIAL THAT A COMPLEX OF STORMS COULD
ORGANIZE ACRS MO LATE TNGT...EVENTUALLY AFFECTING PARTS OF NRN AR
TUE MRNG. IF THIS DOES OCCUR...NRN FCST SITES WOULD NOT BE IMPACTED
UNTIL AFT THIS FCST PD. /44/
PREV DISCUSSION... /ISSUED 357 AM CDT MON AUG 18 2014/
SHORT TERM...TODAY THROUGH THURSDAY NIGHT
A STALLED BOUNDARY REMAINS STRETCHED ACROSS NORTHERN AR EARLY THIS
MORNING...WITH ISOLATED AREAS OF CONVECTION ON GOING DURING THE
OVERNIGHT HOURS. THIS FEATURE WILL BRING AT LEAST SOME CHANCE OF
STORMS TO NORTHERN AND CENTRAL AREAS TODAY...ESPECIALLY AS
DIURNAL HEATING OCCURS.
MEANWHILE...AN UPPER LEVEL LOW IS SWINGING OUT OF THE
ARKLATEX REGION...SPARKING A COMPLEX OF SHOWERS AND THUNDERSTORMS.
THIS AREA OF STORMS WILL SHIFT EASTWARD ACROSS SOUTHERN ARKANSAS
THROUGH THE MORNING HOURS. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE
GIVEN ITS INITIAL SLOW MOVING NATURE. PRECIPITATION CHANCES WILL
CONTINUE ACROSS SOUTHERN AREAS THROUGH THE DAY BEFORE THE SYSTEM
EXITS EAST.
THE AFOREMENTIONED STALL FRONTAL BOUNDARY WILL BEGIN TO LIFT BACK
TO THE NORTH LATE THIS EVENING INTO TUESDAY AS HIGH PRESSURE
BEGINS TO BUILD BACK INTO THE REGION. STILL HAVE PRECIP CHANCES
ACROSS NORTHERN AND EASTERN LOCATIONS THROUGH MID WEEK AS AN
UPPER LEVEL SYSTEM INTERACTS WITH THE BOUNDARY JUST NORTH OF THE
STATE. OTHERWISE...THE MAJORITY OF THE STATE WILL REMAIN DRY.
HOT SUMMERTIME TEMPERATURE WILL RETURN IN FULL FORCE UNDER THE DOME OF
HIGH PRESSURE.
LONG TERM...FRIDAY THROUGH SUNDAY
HIGH PRES ALOFT IS PROGGED TO BE SITUATED ACRS THE REGION LATE THIS
WEEK AND INTO THE WEEKEND. THIS WL RESULT IN TYPICAL SUMMERTIME
CONDS WITH HIGHS IN THE 90S AND LOW TEMPS IN THE UPR 60S TO MID 70S.
AFTN HEAT INDICES ARE FCST TO RANGE FROM 100 TO 104 DEGREES EACH
AFTN. EXPECT LTL IN THE WAY OF DIURNAL CONVECTION TO PROVIDE ANY
RELIEF FM THE HEAT.
&&
.PRELIMINARY POINT TEMPS/POPS...
BATESVILLE AR 74 96 75 98 / 20 20 20 10
CAMDEN AR 75 96 74 96 / 20 10 10 10
HARRISON AR 72 95 71 95 / 20 20 10 10
HOT SPRINGS AR 75 95 74 95 / 20 10 10 10
LITTLE ROCK AR 75 96 75 97 / 20 10 10 10
MONTICELLO AR 74 94 74 96 / 20 10 10 10
MOUNT IDA AR 73 94 73 95 / 20 10 10 10
MOUNTAIN HOME AR 73 96 72 97 / 20 20 20 10
NEWPORT AR 73 95 72 97 / 20 20 20 10
PINE BLUFF AR 73 95 74 96 / 20 10 10 10
RUSSELLVILLE AR 73 97 73 97 / 20 10 10 10
SEARCY AR 72 95 73 96 / 20 20 10 10
STUTTGART AR 72 94 72 95 / 20 20 10 10
&&
.LZK WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AVIATION...51
AREA FORECAST DISCUSSION
NWS LITTLE ROCK AR
1109 AM CDT MON AUG 18 2014
.UPDATE...
CONVECTION STARTING TO CLEAR OUT IN THE SE PART OF THE CWA AND
HAS LEFT A POOL OF RAIN COOLED TEMPERATURES IN ITS WAKE. MAKING
ADJUSTMENTS TO MAX TEMPERATURES TODAY BASED ON THIS...AND ALSO
MAKING TWEAKS TO POPS...DEW POINTS...AND CLOUD COVER BASED ON
CURRENT SYNOPTIC SITUATION.
HRR AND RUC MODELS FORECASTING REDEVELOPMENT OF CONVECTION THIS
AFTERNOON ACROSS PORTIONS OF NORTH CENTRAL AND CENTRAL ARKANSAS. 53
&&
.PREV DISCUSSION... /ISSUED 647 AM CDT MON AUG 18 2014/
AVIATION...18/12Z TAF CYCLE
AREA OF SHRA/TSRA...ASSOCD WITH AN MCV...WL CONT TO TRACK EWD ACRS
CNTRL AND SRN AR THIS MRNG. WIDESPREAD MVFR/IFR CONDS CAN BE
EXPECTED WITH THIS ACTIVITY. CANNOT RULE OUT SOME WDLY SCTD
CONVECTION ACRS THE AREA THIS AFTN. OTHERWISE...VFR CONDS WL
PREVAIL. THERE IS THE POTENTIAL THAT A COMPLEX OF STORMS COULD
ORGANIZE ACRS MO LATE TNGT...EVENTUALLY AFFECTING PARTS OF NRN AR
TUE MRNG. IF THIS DOES OCCUR...NRN FCST SITES WOULD NOT BE IMPACTED
UNTIL AFT THIS FCST PD. /44/
PREV DISCUSSION... /ISSUED 357 AM CDT MON AUG 18 2014/
SHORT TERM...TODAY THROUGH THURSDAY NIGHT
A STALLED BOUNDARY REMAINS STRETCHED ACROSS NORTHERN AR EARLY THIS
MORNING...WITH ISOLATED AREAS OF CONVECTION ON GOING DURING THE
OVERNIGHT HOURS. THIS FEATURE WILL BRING AT LEAST SOME CHANCE OF
STORMS TO NORTHERN AND CENTRAL AREAS TODAY...ESPECIALLY AS
DIURNAL HEATING OCCURS.
MEANWHILE...AN UPPER LEVEL LOW IS SWINGING OUT OF THE
ARKLATEX REGION...SPARKING A COMPLEX OF SHOWERS AND THUNDERSTORMS.
THIS AREA OF STORMS WILL SHIFT EASTWARD ACROSS SOUTHERN ARKANSAS
THROUGH THE MORNING HOURS. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE
GIVEN ITS INITIAL SLOW MOVING NATURE. PRECIPITATION CHANCES WILL
CONTINUE ACROSS SOUTHERN AREAS THROUGH THE DAY BEFORE THE SYSTEM
EXITS EAST.
THE AFOREMENTIONED STALL FRONTAL BOUNDARY WILL BEGIN TO LIFT BACK
TO THE NORTH LATE THIS EVENING INTO TUESDAY AS HIGH PRESSURE
BEGINS TO BUILD BACK INTO THE REGION. STILL HAVE PRECIP CHANCES
ACROSS NORTHERN AND EASTERN LOCATIONS THROUGH MID WEEK AS AN
UPPER LEVEL SYSTEM INTERACTS WITH THE BOUNDARY JUST NORTH OF THE
STATE. OTHERWISE...THE MAJORITY OF THE STATE WILL REMAIN DRY.
HOT SUMMERTIME TEMPERATURE WILL RETURN IN FULL FORCE UNDER THE DOME OF
HIGH PRESSURE.
LONG TERM...FRIDAY THROUGH SUNDAY
HIGH PRES ALOFT IS PROGGED TO BE SITUATED ACRS THE REGION LATE THIS
WEEK AND INTO THE WEEKEND. THIS WL RESULT IN TYPICAL SUMMERTIME
CONDS WITH HIGHS IN THE 90S AND LOW TEMPS IN THE UPR 60S TO MID 70S.
AFTN HEAT INDICES ARE FCST TO RANGE FROM 100 TO 104 DEGREES EACH
AFTN. EXPECT LTL IN THE WAY OF DIURNAL CONVECTION TO PROVIDE ANY
RELIEF FM THE HEAT.
&&
.PRELIMINARY POINT TEMPS/POPS...
BATESVILLE AR 93 74 96 75 / 30 20 20 20
CAMDEN AR 89 75 96 74 / 50 20 10 10
HARRISON AR 93 72 95 71 / 20 20 20 10
HOT SPRINGS AR 90 75 95 74 / 40 20 10 10
LITTLE ROCK AR 89 75 96 75 / 40 20 10 10
MONTICELLO AR 87 74 94 74 / 60 20 10 10
MOUNT IDA AR 92 73 94 73 / 30 20 10 10
MOUNTAIN HOME AR 93 73 96 72 / 20 20 20 20
NEWPORT AR 91 73 95 72 / 40 20 20 20
PINE BLUFF AR 86 73 95 74 / 50 20 10 10
RUSSELLVILLE AR 94 73 97 73 / 30 20 10 10
SEARCY AR 90 72 95 73 / 40 20 20 10
STUTTGART AR 87 72 94 72 / 50 20 20 10
&&
.LZK WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
1050 AM MST MON AUG 18 2014
.UPDATE...AVIATION DISCUSSION UPDATED...
&&
.SYNOPSIS...
AN EARLY SEASON PACIFIC LOW PRESSURE SYSTEM WILL APPROACH THE AREA
TODAY...AND WILL DRAW EVEN MORE MONSOON MOISTURE NORTHWARD BACK INTO
ARIZONA. MORE WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY IS
EXPECTED ACROSS ARIZONA FROM LATE TONIGHT THROUGH MUCH OF THIS WEEK.
WITH THE INCREASE IN HUMIDITIES AND CLOUDS...BELOW NORMAL
TEMPERATURES ARE POSSIBLE BY TUESDAY AND WILL LIKELY CONTINUE
THROUGH THE REMAINDER OF THE WORKWEEK.
&&
.DISCUSSION...
HIGHLY DIFLUENT 300/250 MB WINDS FLOWING ANTI-CYCLONICALLY AROUND A
LARGE OFFSHORE BAJA ANTICYCLONE...WITH A WEAK EMBEDDED SHORTWAVE
PROVIDED SUPPORT FOR PROPAGATING STORMS OVERNIGHT FROM PHOENIX WEST
TO THE COLORADO RIVER. A FEW STORMS STILL REMAINED AT 8 AM MST...BUT
OUTSIDE OUR COUNTY WARNING AREA...CWA...IN SAN BERNARDINO AND MOHAVE
COUNTIES.
CONCERN FOR LATER TODAY THROUGH EARLY TUESDAY IS AN EVEN STRONGER
DIFLUENT/DYNAMIC FLOW ASSOCIATED WITH A SOUTHWARD MOVING EARLY
SEASON TROF ALONG THE WEST COAST. IT LOOKS LIKE A TEMPORARY BREAK IN
POTENTIAL STORM ACTIVITY THROUGH LATE THIS AFTERNOON...THEN THE APEX
OF THE SPREADING DIFLUENT FLOW INCREASES IN THE SOUTHEAST
CA/COLORADO RIVER AREA IN EARNEST BY EVENING. AT THE SAME TIME...
MOISTURE ADVECTION FROM MEXICO INCREASES IN SOUTHWEST AZ IN RESPONSE
TO FALLING ATMOSPHERIC HEIGHTS IN THE MOHAVE DESERT AND IN SOUTHWEST
NEVADA.
THE APEX OF THE DIFLUENT FLOW SHIFTS EAST OVERNIGHT FROM THE
COLORADO RIVER VALLEY INTO THE PHOENIX AREA BY TUESDAY MORNING...
THUS PROVIDING SHWR/TSTM POTENTIAL OVERNIGHT ACROSS MOST OF
SOUTHWEST AND SOUTH CENTRAL AZ. THIS PATTERN IS CERTAINLY A-TYPICAL
AND WARRANTS AN UPGRADE TO PRECIP PROBABILITIES...POPS...CWA WIDE.
UPDATES WERE MADE THIS MORNING TO INCREASE POPS INTO THE CHANCE
CATEGORY ACROSS THE CWA WITHOUT ANY LARGE POP INCONSISTENCIES OR
DISCREPANCIES NEAR ADJACENT OFFICE BOUNDARIES.
OTHERWISE NO OTHER CHANGES ARE EXPECTED THIS MORNING. PREVIOUS
DISCUSSION STILL APPLIES.
.PREVIOUS DISCUSSION...520 AM MST...
TODAY THROUGH WEDNESDAY...
THERE IS NOW EXCELLENT MODEL AGREEMENT ON THE FORECAST FOR OUR CWA
THROUGH WEDNESDAY. BOTH THE GFS AND EURO ARE TRACKING A RATHER
VIGOROUS UPPER LOW CENTER SOUTHWARD ALONG THE CA COAST DURING THIS
PERIOD...WITH INCREASING SOUTHERLY TO SOUTHWESTERLY FLOW AHEAD OF
THIS LOW CENTER PULLING ADDITIONAL MOISTURE NORTHWARD INTO THE
REGION. A REFLECTION OF THIS MOISTURE...A VERY LARGE THUNDERSTORM
COMPLEX CAN BEEN SEEN ON IR AND WATER VAPOR IMAGERY THIS MORNING
OVER EXTREME NORTHWEST SONORA MEXICO...JUST SOUTH OF THE
INTERNATIONAL BORDER. OUTFLOWS FROM THE TS COMPLEX WILL LIKELY PUSH
SFC DEWPOINTS EVEN HIGHER OVER SOUTHWEST AZ THIS MORNING...PROVIDING
THE FUEL FOR TS DEVELOPMENT LATER THIS AFTERNOON. THE LATEST HRRR IS
NOW SHOWING...AFTER A BIT OF A BREAK LATER THIS MORNING AND EARLY
AFTERNOON...WHICH WILL THE ATMOSPHERE A CHANCE TO RELOAD AFTER BEING
WORKED OVER BY LAST NIGHT`S CONVECTIVE ACTIVITY...THUNDERSTORMS
REBUILDING OVER THE HIGHER TERRAIN NORTH AND EAST OF PHX AND OVER SE
AZ...THEN BEGIN TO MOVE THEM INTO THE LOWER ELEVATIONS BY LATE
AFTERNOON AND EARLY EVENING. ONCE AGAIN...THE MAIN IMPACTS FROM
THESE STORMS WILL BE GUSTY WINDS/LOCALIZED BLOWING DUST/BRIEF HEAVY
DOWNPOURS.
SHOWER/TS ACTIVITY WILL LIKELY CONTINUE WELL INTO TONIGHT AND INTO
TUESDAY...ESPECIALLY OVER SOUTH-CENTRAL AND SW AZ AS PWATS RISE INTO
THE 1.80-2.00 INCH RANGE...AND UPPER-LEVEL DIFLUENCE DEVELOPS OVER
THE REGION. HEAVY RAIN/LOCALIZED FLOODING WILL LIKELY BE THE MAIN
ISSUE WITH STORMS LATER TONIGHT AND TUESDAY AS THE VERY MOIST
AIRMASS WILL MAKE THEM MORE EFFICIENT RAINFALL PRODUCERS...WITH
LOCALIZED RAINFALL AMOUNTS AOA 1 INCH LIKELY IN A FEW SPOTS. THE
WIDESPREAD RAINFALL/CLOUDINESS IS EXPECTED TO PUSH HIGH TEMPS ON
TUESDAY BACK BELOW NORMAL...WITH MANY LOWER DESERT LOCATIONS ACROSS
SOUTH-CENTRAL AZ REMAINING BELOW 100F.
A BIT OF A BREAK IS LIKELY ON WEDNESDAY AS THE MAIN MOISTURE PLUME
IS PUSHED TO THE SOUTH AND EAST BY THE APPROACHING UPPER LOW CENTER
AS IT PUSHES INLAND OVER SOUTHERN CA...BUT SCATTERED THUNDERSTORMS
ARE STILL LIKELY TO DEVELOP OVER THE HIGHER TERRAIN NORTH AND EAST
OF PHOENIX.
THURSDAY THROUGH SATURDAY...
SOME MODEL CONSENSUS IS FINALLY BEGINNING TO SHOW UP DURING THIS
PERIOD. THE EURO IS NOW BEGINNING TO SIDE WITH THE GFS...BY TAKING
THE MAIN UPPER LOW CENTER INLAND INTO AZ/NM...WITH CONSIDERABLE
TROPICAL MOISTURE FROM THE REMAINS OF TROPICAL CYCLONE 12E...WHICH
HAS NOW FORMED WELL SOUTHWEST OF THE TIP OF BAJA CALIFORNIA...MOVING
INTO THE DESERT SOUTHWEST AHEAD OF THIS LOW CENTER. THERE IS STILL
CONSIDERABLE TIMING DIFFERENCES BETWEEN THE TWO MODELS...WITH THE
GFS MOVING THE UPPER LOW CENTER INTO AZ LATE THU NIGHT/EARLY
FRIDAY...WHILE THE MUCH SLOWER EURO MOVES IT INTO AZ ON SATURDAY.
EITHER WAY...IT APPEARS MORE-AND-MORE LIKELY THAT A SIGNIFICANT
RAINFALL EVENT COULD DEVELOP OVER AZ...WITH TEMPS FALLING WELL BELOW
NORMAL...WHICH IS VERY UNUSUAL IN MID-LATE AUGUST. THUS...HAVE
RAISED POPS ACROSS THE BOARD DURING THIS PERIOD.
SUNDAY AND MONDAY...
A RETURN TO A MUCH DRIER...AND WARMER PATTERN IS EXPECTED DURING
THIS PERIOD AS BOTH THE GFS AND EURO BEGIN TO DIG A BROAD LONG-WAVE
TROF SOUTHWARD INTO THE INTERMOUNTAIN WEST...WITH WESTERLY FLOW
ALOFT ADVECTING MUCH DRIER AIR INTO THE REGION.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...KSDL...
INCREASING MONSOONAL MOISTURE FROM THE SOUTH WILL LEAD TO BETTER
CHANCES FOR STORMS THIS AFTERNOON AND OVERNIGHT TONIGHT. TIMING OF
THUNDERSTORMS IS SOMEWHAT UNCERTAIN...SO FOR THE MOMENT WILL JUST
KEEP VCTS IN THE TAFS AFTER 01Z...WITH A TRANSITION TO VCSH AFTER
ABOUT 06Z...WITH BKN MID/UPPER LEVEL CLOUD DEBRIS CLOUD DECKS. THERE
IS POTENTIAL LATER TODAY AND THIS EVENING FOR GUSTY VARIABLE OUTFLOW
WINDS...DENSE BLOWING DUST...RESTRICTED VISIBILITY AS WELL AS STORMS
AT THE TERMINALS.
SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
SCT TO BKN MID AND HIGH CLOUDS...WITH BASES AOA 10 KFT ARE EXPECTED
THROUGH TUE MORNING. WINDS SHOULD FAVOR THE SOUTH OR SOUTHEAST NEXT
24 HOURS AT BOTH TAF SITES. GUSTS TO AROUND 22 KT CAN BE EXPECTED
MID TO LATE AFTN AT KBLH.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
WEDNESDAY THROUGH SUNDAY...
DEEP MONSOON MOISTURE WILL CONTINUE THIS PERIOD WITH HIGHER THAN
NORMAL RELATIVE HUMIDITY. A GOOD CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS ARE EXPECTED OVER HIGHER MOUNTAINS OF SOUTHERN GILA
COUNTY EACH DAY...WITH A SLIGHT CHANCE OF THUNDERSTORMS ON THE LOWER
SOUTHWEST AND SOUTH CENTRAL DESERTS. MINIMUM RELATIVE HUMIDITIES WILL
RANGE FROM 25 TO 30 PERCENT. OVERNIGHT RECOVERY WILL BE GOOD.
AFTERNOON TEMPERATURES WILL BE BELOW NORMAL THIS PERIOD ESPECIALLY
FROM PHOENIX EASTWARD. ADDITIONALLY...AFTERNOON/EARLY EVENING WINDS
WILL BE SOUTHWESTERLY AND GENERALLY UNDER 20 MPH...EXCEPT NEAR
THUNDERSTORMS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...VASQUEZ/PERCHA
AVIATION...MCLANE/CB
FIRE WEATHER...VASQUEZ/CB
AREA FORECAST DISCUSSION
NWS TUCSON AZ
910 AM MST MON AUG 18 2014
.SYNOPSIS...AMPLE MOISTURE WILL PROVIDE SCATTERED TO NUMEROUS
THUNDERSTORMS THIS WEEK. SOME STORMS WILL PRODUCE GUSTY WINDS AND
HEAVY HEAVY RAIN THAT MAY PRODUCE FLASH FLOODING. DAYTIME
TEMPERATURES WILL BE BELOW AVERAGE BY MIDWEEK.
&&
.DISCUSSION...IR/VISIBLE SATELLITE IMAGERY AND SURFACE OBSERVATIONS
INDICATE PARTLY CLOUDY SKIES ACROSS ERN SECTIONS TO CLOUDY SKIES
ACROSS WRN PIMA COUNTY. DEWPOINTS AT LOWER ELEVATIONS VALID 16Z
RANGED FROM THE UPPER 50S-MID 60S F...AND THESE TEMPS WERE NEARLY
IDENTICAL TO 24 HOURS AGO. SURFACE TEMPS WERE GENERALLY 2-6 DEGS F
COOLER VERSUS THIS TIME SUN.
18/12Z KTWC SOUNDING TOTAL PRECIP WATER VALUE WAS 1.51 INCHES. A
FAIRLY UNSTABLE ENVIRONMENT EXISTED WITH LIFTED INDEX OF MINUS 6 AND
UNMODIFIED SURFACE-BASED CAPE OF 1639 J/KG. HAVE NOTED THE
CONSIDERABLY STRONGER MID-LEVEL SELY STEERING FLOW FOR THUNDERSTORMS
VERSUS THE PAST 2-3 DAYS. 18/12Z UPPER AIR PLOTS DEPICTED A BROAD
RIDGE OVER THE SWRN CONUS WITH 591 DM HIGH PRESSURE CENTERED OVER
THE FOUR CORNERS REGION. LIGHT TO MODERATE GENERALLY ELY/SELY FLOW
PREVAILED IN THE SURFACE-400 MB LAYER WITH MODERATE WLY FLOW ABOVE
400 MB.
18/14Z RUC HRRR...18/12Z NAM AND 18/12Z UNIV OF AZ WRF-NAM WERE
SIMILAR WITH DEVELOPING SHOWERS/TSTMS BY EARLY THIS AFTERNOON MOSTLY
NEAR THE INTERNATIONAL BORDER ADJACENT SANTA CRUZ/COCHISE COUNTIES.
SHOWERS/TSTMS ARE THEN PROGGED TO MOVE NWWD INTO SOUTH CENTRAL AZ BY
AROUND MIDNIGHT TONIGHT. THIS SCENARIO SEEMS QUITE VIABLE GIVEN THE
AFOREMENTIONED STRONGER MID-LEVEL STORM STEERING FLOW AS OBSERVED
VIA THE 18/12Z KTWC SOUNDING.
BASED ON THESE SOLUTIONS AS WELL AS COORD WITH WFO PSR...HAVE OPTED
TO INCREASE THE INHERITED POPS FOR THIS AFTERNOON THRU TUE. BASED ON
THE COMP REFLECTIVITY/10M WIND SIGNATURES AS PER THE UNIV OF AZ
WRF-NAM...HAVE ADDED AREAS OF BLOWING DUST FOR SOUTH CENTRAL PINAL
COUNTY /AZZ505/ THIS EVENING. MAY OPT TO ISSUE A BLOWING DUST
ADVISORY LATER TODAY FOR SOUTH CENTRAL PINAL COUNTY IF SUBSEQUENT
RUC HRRR AND UNIV OF AZ WRF-GFS SOLUTIONS MIMIC THE UNIV OF AZ
WRF-NAM SOLUTION.
ALSO...BASED THUS FAR ON THE 18/12Z NAM...AM GIVING CONSIDERATION
TOWARD THE POTENTIAL ISSUANCE OF A FLASH FLOOD WATCH MAINLY FOR
LOCALES EAST OF TUCSON TUE. WILL ADDRESS THIS NOTION FURTHER IN THE
AFTERNOON DISCUSSION. OTHERWISE...HIGH TEMPS THIS AFTERNOON SHOULD
AVERAGE ABOUT 3-5 DEGS F COOLER VERSUS TEMPS ACHIEVED SUN.
PLEASE REFER TO THE ADDITIONAL SECTIONS FOR FURTHER DETAIL.
&&
.AVIATION...VALID THRU 19/18Z.
EXPECT SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP SOUTHEAST-TO-
SOUTHWEST OF KTUS BY EARLY THIS AFTERNOON. SCATTERED TO NUMEROUS
-TSRA/-SHRA WILL THEN OCCUR THIS AFTERNOON AND THIS EVENING. MVFR
VISIBILITIES AND BRIEF WIND GUSTS OF 45-50 KTS WILL OCCUR WITH THE
STRONGER TSRA. SCATTERED -SHRA AND ISOLATED -TSRA WILL PREVAIL LATE
TONIGHT INTO TUESDAY MORNING. OTHERWISE...CLOUD DECKS WILL MAINLY BE
AT 6-12K FT AGL AND SURFACE WIND GENERALLY BE LESS THAN 10 KTS THRU
TUESDAY MORNING. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...SCATTERED TO NUMEROUS THUNDERSTORMS WILL OCCUR THIS
WEEK AS AMPLE MOISTURE REMAINS ACROSS SOUTHEAST ARIZONA. THE
STRONGER THUNDERSTORMS WILL PRODUCE STRONG...GUSTY AND ERRATIC
WINDS. OTHERWISE...AFTERNOON MINIMUM RELATIVE HUMIDITIES ARE
FORECAST TO BE MOSTLY IN THE 25-50 PERCENT RANGE AT LOWER ELEVATIONS
FOLLOWED BY GOOD TO EXCELLENT OVERNIGHT RECOVERIES. 20-FOOT WINDS
WILL EXHIBIT NORMAL DIURNAL TRENDS AND BE MOSTLY LESS THAN 15 MPH.
&&
.PREV DISCUSSION...WEDNESDAY...UPPER LOW IS FORECAST TO BE ALONG OR
JUST OFF THE SRN CA CST. MOIST SOUTHERLY FLOW CONTINUES ACROSS SRN
AZ...BUT COULD ALSO SEE SOME DRIER AIR PUSH INTO THE SWRN PART OF
THE STATE. WILL CONTINUE CHANCE OF AFTERNOON/EVENING STORMS.
DEPENDING ON HOW MUCH RAIN FALLS ON TUESDAY WILL HAVE A PART IN
DETERMINING HOW WARM IT WILL GET. 00Z MOS GUIDANCE COOLER THAN WHAT
WE ARE FORECASTING. AGAIN WILL NOT MAKE ANY CHANGES HERE.
THURSDAY INTO THE UPCOMING WEEKEND...STILL SOME UNCERTAINTY OF WHEN
OR IF THE SRN CA UPPER LOW WILL LIFT THRU THE STATE. GFS SAYS
THURSDAY...ECMWF SAYS FRIDAY...CANADIAN KEEPS IT OFFSHORE. WITH SUCH
UNCERTAINTY...WILL MAINTAIN NEAR CLIMO POPS DURING THIS PERIOD.
OVERALL STILL SHAPING UP TO BE A WET WEEK ACROSS SE AZ WITH FLASH
FLOODING A CONCERN MOST OF THE WEEK.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
FRANCIS
PREVIOUS DISCUSSION...GLUECK
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
844 AM MST MON AUG 18 2014
.SYNOPSIS...
AN EARLY SEASON PACIFIC LOW PRESSURE SYSTEM WILL APPROACH THE AREA
TODAY...AND WILL DRAW EVEN MORE MONSOON MOISTURE NORTHWARD BACK INTO
ARIZONA. MORE WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY IS
EXPECTED ACROSS ARIZONA FROM LATE TONIGHT THROUGH MUCH OF THIS WEEK.
WITH THE INCREASE IN HUMIDITIES AND CLOUDS...BELOW NORMAL
TEMPERATURES ARE POSSIBLE BY TUESDAY AND WILL LIKELY CONTINUE
THROUGH THE REMAINDER OF THE WORKWEEK.
&&
.DISCUSSION...
HIGHLY DIFLUENT 300/250 MB WINDS FLOWING ANTI-CYCLONICALLY AROUND A
LARGE OFFSHORE BAJA ANTICYCLONE...WITH A WEAK EMBEDDED SHORTWAVE
PROVIDED SUPPORT FOR PROPAGATING STORMS OVERNIGHT FROM PHOENIX WEST
TO THE COLORADO RIVER. A FEW STORMS STILL REMAINED AT 8 AM MST...BUT
OUTSIDE OUR COUNTY WARNING AREA...CWA...IN SAN BERNARDINO AND MOHAVE
COUNTIES.
CONCERN FOR LATER TODAY THROUGH EARLY TUESDAY IS AN EVEN STRONGER
DIFLUENT/DYNAMIC FLOW ASSOCIATED WITH A SOUTHWARD MOVING EARLY
SEASON TROF ALONG THE WEST COAST. IT LOOKS LIKE A TEMPORARY BREAK IN
POTENTIAL STORM ACTIVITY THROUGH LATE THIS AFTERNOON...THEN THE APEX
OF THE SPREADING DIFLUENT FLOW INCREASES IN THE SOUTHEAST
CA/COLORADO RIVER AREA IN EARNEST BY EVENING. AT THE SAME TIME...
MOISTURE ADVECTION FROM MEXICO INCREASES IN SOUTHWEST AZ IN RESPONSE
TO FALLING ATMOSPHERIC HEIGHTS IN THE MOHAVE DESERT AND IN SOUTHWEST
NEVADA.
THE APEX OF THE DIFLUENT FLOW SHIFTS EAST OVERNIGHT FROM THE
COLORADO RIVER VALLEY INTO THE PHOENIX AREA BY TUESDAY MORNING...
THUS PROVIDING SHWR/TSTM POTENTIAL OVERNIGHT ACROSS MOST OF
SOUTHWEST AND SOUTH CENTRAL AZ. THIS PATTERN IS CERTAINLY A-TYPICAL
AND WARRANTS AN UPGRADE TO PRECIP PROBABILITIES...POPS...CWA WIDE.
UPDATES WERE MADE THIS MORNING TO INCREASE POPS INTO THE CHANCE
CATEGORY ACROSS THE CWA WITHOUT ANY LARGE POP INCONSISTENCIES OR
DISCREPANCIES NEAR ADJACENT OFFICE BOUNDARIES.
OTHERWISE NO OTHER CHANGES ARE EXPECTED THIS MORNING. PREVIOUS
DISCUSSION STILL APPLIES.
.PREVIOUS DISCUSSION...520 AM MST...
TODAY THROUGH WEDNESDAY...
THERE IS NOW EXCELLENT MODEL AGREEMENT ON THE FORECAST FOR OUR CWA
THROUGH WEDNESDAY. BOTH THE GFS AND EURO ARE TRACKING A RATHER
VIGOROUS UPPER LOW CENTER SOUTHWARD ALONG THE CA COAST DURING THIS
PERIOD...WITH INCREASING SOUTHERLY TO SOUTHWESTERLY FLOW AHEAD OF
THIS LOW CENTER PULLING ADDITIONAL MOISTURE NORTHWARD INTO THE
REGION. A REFLECTION OF THIS MOISTURE...A VERY LARGE THUNDERSTORM
COMPLEX CAN BEEN SEEN ON IR AND WATER VAPOR IMAGERY THIS MORNING
OVER EXTREME NORTHWEST SONORA MEXICO...JUST SOUTH OF THE
INTERNATIONAL BORDER. OUTFLOWS FROM THE TS COMPLEX WILL LIKELY PUSH
SFC DEWPOINTS EVEN HIGHER OVER SOUTHWEST AZ THIS MORNING...PROVIDING
THE FUEL FOR TS DEVELOPMENT LATER THIS AFTERNOON. THE LATEST HRRR IS
NOW SHOWING...AFTER A BIT OF A BREAK LATER THIS MORNING AND EARLY
AFTERNOON...WHICH WILL THE ATMOSPHERE A CHANCE TO RELOAD AFTER BEING
WORKED OVER BY LAST NIGHT`S CONVECTIVE ACTIVITY...THUNDERSTORMS
REBUILDING OVER THE HIGHER TERRAIN NORTH AND EAST OF PHX AND OVER SE
AZ...THEN BEGIN TO MOVE THEM INTO THE LOWER ELEVATIONS BY LATE
AFTERNOON AND EARLY EVENING. ONCE AGAIN...THE MAIN IMPACTS FROM
THESE STORMS WILL BE GUSTY WINDS/LOCALIZED BLOWING DUST/BRIEF HEAVY
DOWNPOURS.
SHOWER/TS ACTIVITY WILL LIKELY CONTINUE WELL INTO TONIGHT AND INTO
TUESDAY...ESPECIALLY OVER SOUTH-CENTRAL AND SW AZ AS PWATS RISE INTO
THE 1.80-2.00 INCH RANGE...AND UPPER-LEVEL DIFLUENCE DEVELOPS OVER
THE REGION. HEAVY RAIN/LOCALIZED FLOODING WILL LIKELY BE THE MAIN
ISSUE WITH STORMS LATER TONIGHT AND TUESDAY AS THE VERY MOIST
AIRMASS WILL MAKE THEM MORE EFFICIENT RAINFALL PRODUCERS...WITH
LOCALIZED RAINFALL AMOUNTS AOA 1 INCH LIKELY IN A FEW SPOTS. THE
WIDESPREAD RAINFALL/CLOUDINESS IS EXPECTED TO PUSH HIGH TEMPS ON
TUESDAY BACK BELOW NORMAL...WITH MANY LOWER DESERT LOCATIONS ACROSS
SOUTH-CENTRAL AZ REMAINING BELOW 100F.
A BIT OF A BREAK IS LIKELY ON WEDNESDAY AS THE MAIN MOISTURE PLUME
IS PUSHED TO THE SOUTH AND EAST BY THE APPROACHING UPPER LOW CENTER
AS IT PUSHES INLAND OVER SOUTHERN CA...BUT SCATTERED THUNDERSTORMS
ARE STILL LIKELY TO DEVELOP OVER THE HIGHER TERRAIN NORTH AND EAST
OF PHOENIX.
THURSDAY THROUGH SATURDAY...
SOME MODEL CONSENSUS IS FINALLY BEGINNING TO SHOW UP DURING THIS
PERIOD. THE EURO IS NOW BEGINNING TO SIDE WITH THE GFS...BY TAKING
THE MAIN UPPER LOW CENTER INLAND INTO AZ/NM...WITH CONSIDERABLE
TROPICAL MOISTURE FROM THE REMAINS OF TROPICAL CYCLONE 12E...WHICH
HAS NOW FORMED WELL SOUTHWEST OF THE TIP OF BAJA CALIFORNIA...MOVING
INTO THE DESERT SOUTHWEST AHEAD OF THIS LOW CENTER. THERE IS STILL
CONSIDERABLE TIMING DIFFERENCES BETWEEN THE TWO MODELS...WITH THE
GFS MOVING THE UPPER LOW CENTER INTO AZ LATE THU NIGHT/EARLY
FRIDAY...WHILE THE MUCH SLOWER EURO MOVES IT INTO AZ ON SATURDAY.
EITHER WAY...IT APPEARS MORE-AND-MORE LIKELY THAT A SIGNIFICANT
RAINFALL EVENT COULD DEVELOP OVER AZ...WITH TEMPS FALLING WELL BELOW
NORMAL...WHICH IS VERY UNUSUAL IN MID-LATE AUGUST. THUS...HAVE
RAISED POPS ACROSS THE BOARD DURING THIS PERIOD.
SUNDAY AND MONDAY...
A RETURN TO A MUCH DRIER...AND WARMER PATTERN IS EXPECTED DURING
THIS PERIOD AS BOTH THE GFS AND EURO BEGIN TO DIG A BROAD LONG-WAVE
TROF SOUTHWARD INTO THE INTERMOUNTAIN WEST...WITH WESTERLY FLOW
ALOFT ADVECTING MUCH DRIER AIR INTO THE REGION.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...KSDL...
CONVECTION CONTINUES THIS MORNING ACROSS NORTHERN PORTIONS OF THE
VALLEY...AFFECTING KSDL AND POSSIBLY KPHX. WILL KEEP VCTS IN THE
TAFS THRU 14Z OR SO...MAY HAVE TO UPGRADE TO TEMPO GROUPS FOR
CONVECTION SHOULD STORMS CONTINUE TO DEVELOP. OTHERWISE...INCREASING
MONSOONAL MOISTURE FROM THE SOUTH WILL LEAD TO BETTER CHANCES FOR
STORMS THIS AFTERNOON AND OVERNIGHT TONIGHT. FOR THE MOMENT DUE TO
LACK OF CONFIDENCE IN TIMING AND STRENGTH OF THE STORMS...WILL
SIMPLY PUT VCTS IN THE TAFS AFTER 01Z...TRANSITION TO VCSH AFTER
ABOUT 06Z...WITH BKN MID/UPPER LEVEL CLOUD DEBRIS CLOUD DECKS.
POTENTIAL IS THERE LATER TODAY AND THIS EVENING FOR GUSTY VARIABLE
OUTFLOW WINDS...DENSE BLOWING DUST...RESTRICTED VISIBILITY AS WELL
AS STORMS AT THE TERMINALS. WILL UPDATE TAFS LATER TODAY AS NEEDED.
SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
STRONG GUSTY EASTERLY OUTFLOW WINDS PERSIST AT KIPL...AND SHOW
LITTLE SIGN OF EASING UP SO WILL KEEP ELY GUSTS TO 32KT WITH VSBYS
TO 4SM AND LOW CIGS AS WELL THRU 14Z. HOPEFULLY THE WINDS WILL HAVE
TAPERED OFF BY THEN. MAY SEE A FEW SHOWERS OR HIGH BASED STORMS IN
THE AREA THRU MID MORNING AFFECTING BOTH KIPL AND BLH...WILL KEEP
VCSH THRU MID/LATE MORNING AND AMEND FOR THUNDER AS NEEDED.
OTHERWISE WINDS SHOULD FAVOR THE SOUTH OR SOUTHEAST NEXT 24 HOURS AT
BOTH TAF SITES. FROM 18Z THRU TUESDAY MORNING...EXPECT MAINLY
MID/UPPER LEVEL SCT-BKN CLOUD DECKS...THREAT FOR SHOWERS/STORMS NOT
HIGH ENOUGH TO MENTION IN THE TAFS.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
WEDNESDAY THROUGH SUNDAY...
DEEP MONSOON MOISTURE WILL CONTINUE THIS PERIOD WITH HIGHER THAN
NORMAL RELATIVE HUMIDITY. A GOOD CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS ARE EXPECTED OVER HIGHER MOUNTAINS OF SOUTHERN GILA
COUNTY EACH DAY...WITH A SLIGHT CHANCE OF THUNDERSTORMS ON THE LOWER
SOUTHWEST AND SOUTH CENTRAL DESERTS. MINIMUM RELATIVE HUMIDITIES WILL
RANGE FROM 25 TO 30 PERCENT. OVERNIGHT RECOVERY WILL BE GOOD.
AFTERNOON TEMPERATURES WILL BE BELOW NORMAL THIS PERIOD ESPECIALLY
FROM PHOENIX EASTWARD. ADDITIONALLY...AFTERNOON/EARLY EVENING WINDS
WILL BE SOUTHWESTERLY AND GENERALLY UNDER 20 MPH...EXCEPT NEAR
THUNDERSTORMS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...VASQUEZ/PERCHA
AVIATION...CB
FIRE WEATHER...VASQUEZ/CB
AREA FORECAST DISCUSSION...UPDATED
NWS PHOENIX AZ
520 AM MST MON AUG 18 2014
.UPDATE...UPDATED AVIATION AND FIRE WEATHER DISCUSSIONS.
&&
.SYNOPSIS...
AN EARLY SEASON PACIFIC LOW PRESSURE SYSTEM WILL APPROACH THE AREA
TODAY...AND WILL DRAW EVEN MORE MONSOON MOISTURE NORTHWARD BACK INTO
ARIZONA. MORE WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY IS
EXPECTED ACROSS ARIZONA FROM LATE TONIGHT THROUGH MUCH OF THIS WEEK.
WITH THE INCREASE IN HUMIDITIES AND CLOUDS...BELOW NORMAL
TEMPERATURES ARE POSSIBLE BY TUESDAY AND WILL LIKELY CONTINUE
THROUGH THE REMAINDER OF THE WORKWEEK.
&&
.DISCUSSION...
TODAY THROUGH WEDNESDAY...
THERE IS NOW EXCELLENT MODEL AGREEMENT ON THE FORECAST FOR OUR CWA
THROUGH WEDNESDAY. BOTH THE GFS AND EURO ARE TRACKING A RATHER
VIGOROUS UPPER LOW CENTER SOUTHWARD ALONG THE CA COAST DURING THIS
PERIOD...WITH INCREASING SOUTHERLY TO SOUTHWESTERLY FLOW AHEAD OF
THIS LOW CENTER PULLING ADDITIONAL MOISTURE NORTHWARD INTO THE
REGION. A REFLECTION OF THIS MOISTURE...A VERY LARGE THUNDERSTORM
COMPLEX CAN BEEN SEEN ON IR AND WATER VAPOR IMAGERY THIS MORNING
OVER EXTREME NORTHWEST SONORA MEXICO...JUST SOUTH OF THE
INTERNATIONAL BORDER. OUTFLOWS FROM THE TS COMPLEX WILL LIKELY PUSH
SFC DEWPOINTS EVEN HIGHER OVER SOUTHWEST AZ THIS MORNING...PROVIDING
THE FUEL FOR TS DEVELOPMENT LATER THIS AFTERNOON. THE LATEST HRRR IS
NOW SHOWING...AFTER A BIT OF A BREAK LATER THIS MORNING AND EARLY
AFTERNOON...WHICH WILL THE ATMOSPHERE A CHANCE TO RELOAD AFTER BEING
WORKED OVER BY LAST NIGHT`S CONVECTIVE ACTIVITY...THUNDERSTORMS
REBUILDING OVER THE HIGHER TERRAIN NORTH AND EAST OF PHX AND OVER SE
AZ...THEN BEGIN TO MOVE THEM INTO THE LOWER ELEVATIONS BY LATE
AFTERNOON AND EARLY EVENING. ONCE AGAIN...THE MAIN IMPACTS FROM
THESE STORMS WILL BE GUSTY WINDS/LOCALIZED BLOWING DUST/BRIEF HEAVY
DOWNPOURS.
SHOWER/TS ACTIVITY WILL LIKELY CONTINUE WELL INTO TONIGHT AND INTO
TUESDAY...ESPECIALLY OVER SOUTH-CENTRAL AND SW AZ AS PWATS RISE INTO
THE 1.80-2.00 INCH RANGE...AND UPPER-LEVEL DIFLUENCE DEVELOPS OVER
THE REGION. HEAVY RAIN/LOCALIZED FLOODING WILL LIKELY BE THE MAIN
ISSUE WITH STORMS LATER TONIGHT AND TUESDAY AS THE VERY MOIST
AIRMASS WILL MAKE THEM MORE EFFICIENT RAINFALL PRODUCERS...WITH
LOCALIZED RAINFALL AMOUNTS AOA 1 INCH LIKELY IN A FEW SPOTS. THE
WIDESPREAD RAINFALL/CLOUDINESS IS EXPECTED TO PUSH HIGH TEMPS ON
TUESDAY BACK BELOW NORMAL...WITH MANY LOWER DESERT LOCATIONS ACROSS
SOUTH-CENTRAL AZ REMAINING BELOW 100F.
A BIT OF A BREAK IS LIKELY ON WEDNESDAY AS THE MAIN MOISTURE PLUME
IS PUSHED TO THE SOUTH AND EAST BY THE APPROACHING UPPER LOW CENTER
AS IT PUSHES INLAND OVER SOUTHERN CA...BUT SCATTERED THUNDERSTORMS
ARE STILL LIKELY TO DEVELOP OVER THE HIGHER TERRAIN NORTH AND EAST
OF PHOENIX.
THURSDAY THROUGH SATURDAY...
SOME MODEL CONSENSUS IS FINALLY BEGINNING TO SHOW UP DURING THIS
PERIOD. THE EURO IS NOW BEGINNING TO SIDE WITH THE GFS...BY TAKING
THE MAIN UPPER LOW CENTER INLAND INTO AZ/NM...WITH CONSIDERABLE
TROPICAL MOISTURE FROM THE REMAINS OF TROPICAL CYCLONE 12E...WHICH
HAS NOW FORMED WELL SOUTHWEST OF THE TIP OF BAJA CALIFORNIA...MOVING
INTO THE DESERT SOUTHWEST AHEAD OF THIS LOW CENTER. THERE IS STILL
CONSIDERABLE TIMING DIFFERENCES BETWEEN THE TWO MODELS...WITH THE
GFS MOVING THE UPPER LOW CENTER INTO AZ LATE THU NIGHT/EARLY
FRIDAY...WHILE THE MUCH SLOWER EURO MOVES IT INTO AZ ON SATURDAY.
EITHER WAY...IT APPEARS MORE-AND-MORE LIKELY THAT A SIGNIFICANT
RAINFALL EVENT COULD DEVELOP OVER AZ...WITH TEMPS FALLING WELL BELOW
NORMAL...WHICH IS VERY UNUSUAL IN MID-LATE AUGUST. THUS...HAVE
RAISED POPS ACROSS THE BOARD DURING THIS PERIOD.
SUNDAY AND MONDAY...
A RETURN TO A MUCH DRIER...AND WARMER PATTERN IS EXPECTED DURING
THIS PERIOD AS BOTH THE GFS AND EURO BEGIN TO DIG A BROAD LONG-WAVE
TROF SOUTHWARD INTO THE INTERMOUNTAIN WEST...WITH WESTERLY FLOW
ALOFT ADVECTING MUCH DRIER AIR INTO THE REGION.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...KSDL...
CONVECTION CONTINUES THIS MORNING ACROSS NORTHERN PORTIONS OF THE
VALLEY...AFFECTING KSDL AND POSSIBLY KPHX. WILL KEEP VCTS IN THE
TAFS THRU 14Z OR SO...MAY HAVE TO UPGRADE TO TEMPO GROUPS FOR
CONVECTION SHOULD STORMS CONTINUE TO DEVELOP. OTHERWISE...INCREASING
MONSOONAL MOISTURE FROM THE SOUTH WILL LEAD TO BETTER CHANCES FOR
STORMS THIS AFTERNOON AND OVERNIGHT TONIGHT. FOR THE MOMENT DUE TO
LACK OF CONFIDENCE IN TIMING AND STRENGTH OF THE STORMS...WILL
SIMPLY PUT VCTS IN THE TAFS AFTER 01Z...TRANSITION TO VCSH AFTER
ABOUT 06Z...WITH BKN MID/UPPER LEVEL CLOUD DEBRIS CLOUD DECKS.
POTENTIAL IS THERE LATER TODAY AND THIS EVENING FOR GUSTY VARIABLE
OUTFLOW WINDS...DENSE BLOWING DUST...RESTRICTED VISIBILITY AS WELL
AS STORMS AT THE TERMINALS. WILL UPDATE TAFS LATER TODAY AS NEEDED.
SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
STRONG GUSTY EASTERLY OUTFLOW WINDS PERSIST AT KIPL...AND SHOW
LITTLE SIGN OF EASING UP SO WILL KEEP ELY GUSTS TO 32KT WITH VSBYS
TO 4SM AND LOW CIGS AS WELL THRU 14Z. HOPEFULLY THE WINDS WILL HAVE
TAPERED OFF BY THEN. MAY SEE A FEW SHOWERS OR HIGH BASED STORMS IN
THE AREA THRU MID MORNING AFFECTING BOTH KIPL AND BLH...WILL KEEP
VCSH THRU MID/LATE MORNING AND AMEND FOR THUNDER AS NEEDED.
OTHERWISE WINDS SHOULD FAVOR THE SOUTH OR SOUTHEAST NEXT 24 HOURS AT
BOTH TAF SITES. FROM 18Z THRU TUESDAY MORNING...EXPECT MAINLY
MID/UPPER LEVEL SCT-BKN CLOUD DECKS...THREAT FOR SHOWERS/STORMS NOT
HIGH ENOUGH TO MENTION IN THE TAFS.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
WEDNESDAY THROUGH SUNDAY...
DEEP MONSOON MOISTURE WILL CONTINUE THIS PERIOD WITH HIGHER THAN
NORMAL RELATIVE HUMIDITY. A GOOD CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS ARE EXPECTED OVER HIGHER MOUNTAINS OF SOUTHERN GILA
COUNTY EACH DAY...WITH A SLIGHT CHANCE OF THUNDERSTORMS ON THE LOWER
SOUTHWEST AND SOUTH CENTRAL DESERTS. MINIMUM RELATIVE HUMIDITIES WILL
RANGE FROM 25 TO 30 PERCENT. OVERNIGHT RECOVERY WILL BE GOOD.
AFTERNOON TEMPERATURES WILL BE BELOW NORMAL THIS PERIOD ESPECIALLY
FROM PHOENIX EASTWARD. ADDITIONALLY...AFTERNOON/EARLY EVENING WINDS
WILL BE SOUTHWESTERLY AND GENERALLY UNDER 20 MPH...EXCEPT NEAR
THUNDERSTORMS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...PERCHA
AVIATION...CB
FIRE WEATHER...VASQUEZ/CB
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
215 AM MST MON AUG 18 2014
.SYNOPSIS...
AN EARLY SEASON PACIFIC LOW PRESSURE SYSTEM WILL APPROACH THE AREA
TODAY...AND WILL DRAW EVEN MORE MONSOON MOISTURE NORTHWARD BACK INTO
ARIZONA. MORE WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY IS
EXPECTED ACROSS ARIZONA FROM LATE TONIGHT THROUGH MUCH OF THIS WEEK.
WITH THE INCREASE IN HUMIDITIES AND CLOUDS...BELOW NORMAL
TEMPERATURES ARE POSSIBLE BY TUESDAY AND WILL LIKELY CONTINUE
THROUGH THE REMAINDER OF THE WORKWEEK.
&&
.DISCUSSION...
TODAY THROUGH WEDNESDAY...
THERE IS NOW EXCELLENT MODEL AGREEMENT ON THE FORECAST FOR OUR CWA
THROUGH WEDNESDAY. BOTH THE GFS AND EURO ARE TRACKING A RATHER
VIGOROUS UPPER LOW CENTER SOUTHWARD ALONG THE CA COAST DURING THIS
PERIOD...WITH INCREASING SOUTHERLY TO SOUTHWESTERLY FLOW AHEAD OF
THIS LOW CENTER PULLING ADDITIONAL MOISTURE NORTHWARD INTO THE
REGION. A REFLECTION OF THIS MOISTURE...A VERY LARGE THUNDERSTORM
COMPLEX CAN BEEN SEEN ON IR AND WATER VAPOR IMAGERY THIS MORNING
OVER EXTREME NORTHWEST SONORA MEXICO...JUST SOUTH OF THE
INTERNATIONAL BORDER. OUTFLOWS FROM THE TS COMPLEX WILL LIKELY PUSH
SFC DEWPOINTS EVEN HIGHER OVER SOUTHWEST AZ THIS MORNING...PROVIDING
THE FUEL FOR TS DEVELOPMENT LATER THIS AFTERNOON. THE LATEST HRRR IS
NOW SHOWING...AFTER A BIT OF A BREAK LATER THIS MORNING AND EARLY
AFTERNOON...WHICH WILL THE ATMOSPHERE A CHANCE TO RELOAD AFTER BEING
WORKED OVER BY LAST NIGHT`S CONVECTIVE ACTIVITY...THUNDERSTORMS
REBUILDING OVER THE HIGHER TERRAIN NORTH AND EAST OF PHX AND OVER SE
AZ...THEN BEGIN TO MOVE THEM INTO THE LOWER ELEVATIONS BY LATE
AFTERNOON AND EARLY EVENING. ONCE AGAIN...THE MAIN IMPACTS FROM
THESE STORMS WILL BE GUSTY WINDS/LOCALIZED BLOWING DUST/BRIEF HEAVY
DOWNPOURS.
SHOWER/TS ACTIVITY WILL LIKELY CONTINUE WELL INTO TONIGHT AND INTO
TUESDAY...ESPECIALLY OVER SOUTH-CENTRAL AND SW AZ AS PWATS RISE INTO
THE 1.80-2.00 INCH RANGE...AND UPPER-LEVEL DIFLUENCE DEVELOPS OVER
THE REGION. HEAVY RAIN/LOCALIZED FLOODING WILL LIKELY BE THE MAIN
ISSUE WITH STORMS LATER TONIGHT AND TUESDAY AS THE VERY MOIST
AIRMASS WILL MAKE THEM MORE EFFICIENT RAINFALL PRODUCERS...WITH
LOCALIZED RAINFALL AMOUNTS AOA 1 INCH LIKELY IN A FEW SPOTS. THE
WIDESPREAD RAINFALL/CLOUDINESS IS EXPECTED TO PUSH HIGH TEMPS ON
TUESDAY BACK BELOW NORMAL...WITH MANY LOWER DESERT LOCATIONS ACROSS
SOUTH-CENTRAL AZ REMAINING BELOW 100F.
A BIT OF A BREAK IS LIKELY ON WEDNESDAY AS THE MAIN MOISTURE PLUME
IS PUSHED TO THE SOUTH AND EAST BY THE APPROACHING UPPER LOW CENTER
AS IT PUSHES INLAND OVER SOUTHERN CA...BUT SCATTERED THUNDERSTORMS
ARE STILL LIKELY TO DEVELOP OVER THE HIGHER TERRAIN NORTH AND EAST
OF PHOENIX.
THURSDAY THROUGH SATURDAY...
SOME MODEL CONSENSUS IS FINALLY BEGINNING TO SHOW UP DURING THIS
PERIOD. THE EURO IS NOW BEGINNING TO SIDE WITH THE GFS...BY TAKING
THE MAIN UPPER LOW CENTER INLAND INTO AZ/NM...WITH CONSIDERABLE
TROPICAL MOISTURE FROM THE REMAINS OF TROPICAL CYCLONE 12E...WHICH
HAS NOW FORMED WELL SOUTHWEST OF THE TIP OF BAJA CALIFORNIA...MOVING
INTO THE DESERT SOUTHWEST AHEAD OF THIS LOW CENTER. THERE IS STILL
CONSIDERABLE TIMING DIFFERENCES BETWEEN THE TWO MODELS...WITH THE
GFS MOVING THE UPPER LOW CENTER INTO AZ LATE THU NIGHT/EARLY
FRIDAY...WHILE THE MUCH SLOWER EURO MOVES IT INTO AZ ON SATURDAY.
EITHER WAY...IT APPEARS MORE-AND-MORE LIKELY THAT A SIGNIFICANT
RAINFALL EVENT COULD DEVELOP OVER AZ...WITH TEMPS FALLING WELL BELOW
NORMAL...WHICH IS VERY UNUSUAL IN MID-LATE AUGUST. THUS...HAVE
RAISED POPS ACROSS THE BOARD DURING THIS PERIOD.
SUNDAY AND MONDAY...
A RETURN TO A MUCH DRIER...AND WARMER PATTERN IS EXPECTED DURING
THIS PERIOD AS BOTH THE GFS AND EURO BEGIN TO DIG A BROAD LONG-WAVE
TROF SOUTHWARD INTO THE INTERMOUNTAIN WEST...WITH WESTERLY FLOW
ALOFT ADVECTING MUCH DRIER AIR INTO THE REGION.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...KSDL...
CONVECTION SLOWLY DYING OFF ACROSS THE AREA AND CONDITIONS SHOULD
CONTINUE TO IMPROVE FOR THE REST OF THE EVENING/OVERNIGHT HOURS.
EXPECT BREEZY EAST WINDS TO GRADUALLY WEAKEN OVERNIGHT BUT RETAIN
THEIR EASTERLY COMPONENT THROUGH LATE MORNING. CONVECTION POSSIBLE
ONCE AGAIN ACROSS THE AREA MONDAY AFTERNOON ESPECIALLY LATE IN THE
TAF PERIOD.
SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
STORMS HAVE BEEN CONFINED TO ARIZONA THIS EVENING BUT OUTFLOWS WILL
LIKELY MAKE THEIR WAY INTO BLH AFTER 06Z. MEANWHILE STORMS OVER
SONORA ARE MAKING A PUSH TOWARD THE REGION AND COULD REDEVELOP OVER
SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA LATE TONIGHT/EARLY MONDAY
MORNING. CONFIDENCE IN THIS SOLUTION IS VERY LOW BUT I WILL MAKE A
MENTION OF VCSH IN BOTH TAFS AROUND 12Z. PRIMARY THREATS WILL BE
GUSTY WINDS AND REDUCED VSBYS. STORMS POSSIBLE ONCE AGAIN MONDAY
AFTERNOON.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
WEDNESDAY THROUGH SUNDAY...
DEEP MONSOON MOISTURE WILL CONTINUE THIS PERIOD WITH HIGHER THAN
NORMAL RELATIVE HUMIDITY. A GOOD CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS ARE EXPECTED OVER HIGHER MOUNTAINS OF SOUTHERN GILA
COUNTY EACH DAY...WITH A SLIGHT CHANCE OF THUNDERSTORMS ON THE LOWER
SOUTHWEST AND SOUTH CENTRAL DESERTS. MINIMUM RELATIVE HUMIDITIES WILL
RANGE FROM 25 TO 30 PERCENT. OVERNIGHT RECOVERY WILL BE FAIR.
AFTERNOON TEMPERATURES WILL BE SLIGHTLY BELOW NORMAL THIS PERIOD.
ADDITIONALLY...AFTERNOON/EARLY EVENING WINDS WILL BE SOUTHWESTERLY
AND GENERALLY UNDER 20 MPH...EXCEPT NEAR THUNDERSTORMS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...PERCHA
AVIATION...LEINS
FIRE WEATHER...VASQUEZ
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
858 PM PDT TUE AUG 19 2014
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE REGION AND INCREASE
THE NIGHT THROUGH MORNING CLOUDS AND FOG THROUGH SATURDAY. THE
MOIST AIR MASS WILL BRING LOCAL DRIZZLE...AND A SLIGHT CHANCE OF
SHOWERS OR THUNDERSTORMS TO THE SOUTHLAND THROUGH THURSDAY. A
HIGH PRESSURE SYSTEM WILL LIKELY ESTABLISH FOR EARLY NEXT WEEK
WITH ABOVE NORMAL TEMPERATURES.
&&
.UPDATE...
THE WATER VAPOR IMAGERY INDICATES A LOW PRESSURE SYSTEM
CONTINUING TO DIG SOUTH OFF THE SOUTHERN CALIFORNIA COAST THIS
EVENING. SOME CONVECTION HAS FIRED OFF TO THE SOUTH AND EAST OF
THE AREA...BUT THE AREA HAS REMAINED DRY. A DEEP MARINE LAYER
SHOULD BRING AN EXTENSIVE MARINE LAYER INDUCED STRATUS FIELD TO
THE MUCH OF THE COASTAL AND VALLEY AREAS LATER TONIGHT. THE LATEST
FOG PRODUCT IS GIVING INDICATIONS OF A RAPID FILLING-IN OF
STRATUS LATE THIS EVENING. DRIZZLE OR LIGHT SHOWERS FROM THE
STRATUS DECK CANNOT BE RULED AS THE INSTABILITY OF THE TROUGH
APPROACHES AND RAPID DEEPENING OF THE MARINE LAYER TAKES PLACE.
THE LATEST NAM-WRF AND RAP SOLUTIONS SUGGEST THE TIMING OF THE
CONVECTION OCCURRING A LITTLE EARLIER THAN PREVIOUSLY THOUGHT.
BOTH 00Z NAM-WRF SOLUTIONS AND THE LATEST RAP SOLUTIONS SUGGEST AN
AREA OF NEGATIVE LIFTED INDEX VALUES FORMING OVER THE SOUTHERN
COASTAL WATERS LATE TONIGHT WHEN THE COLDEST AIR ALOFT WITH THE
TROUGH MOVES INTO THE REGION. AN AREA OF DIFLUENCE FLOW ALOFT
SHOULD DEVELOP AHEAD OF THE MAIN VORTICITY MAXIMUM AND SHOULD
ALLOW FOR SHOWERS AND THUNDERSTORMS TO FIRE...EVEN ABOVE THE
MARINE LAYER STRATUS DECK. POPS HAVE BEEN BUMPED FOR THE COASTAL
WATERS AND THE LOS ANGELES COUNTY COAST AFTER MIDNIGHT TONIGHT.
THE LATEST NAM-WRF SOLUTIONS CONTINUE TO SLOW THE TROUGH...BEING
LESS PROGRESSIVE RELATIVE TO THE GFS AND ECMWF SOLUTIONS. IF NAM-
WRF SOLUTIONS PLAY OUT...POPS AND WEATHER MAY NEED TO BE ADDED FOR
THURSDAY AS THE TROUGH AXIS LINGERS OVER THE AREA. WHILE THE NAM-
WRF SOLUTIONS REMAIN THE OUTLIER...THE TROUGH IS CUT-OFF FROM THE
FLOW AND TYPICALLY MODEL PERFORMANCE WITH CLOSED AND CUT-OFF LOWS
WOULD FAVOR NAM-WRF SOLUTIONS FOR SOUTHERN CALIFORNIA AND
SOUTHWESTERN UNITED STATES. WITH THE NWS WEATHER PREDICTION CENTER
MENTIONING SREF SOLUTIONS FAVORING RETROGRESSION OF THE
TROUGH...IT IS POSSIBLE THAT THE NAM-WRF SOLUTION MAY NOT BE TOO
FAR OFF. THE NEXT SHIFT WILL BE BRIEFED ABOUT POPS AND WEATHER
POSSIBILITIES FOR THURSDAY.
&&
.PREV DISCUSSION...
SHORT TERM...THE UPPER LOW MOVES SOUTHEAST TO THE HIGH DESERTS
ON THURSDAY. THE LAST BIT OF INSTABILITY AND MOISTURE WILL BE OVER
THE EASTERN SAN GABRIEL MOUNTAINS FOR A CONTINUED SLIGHT CHANCE OF
THUNDERSTORMS. A SHALLOWER MARINE LAYER IS LIKELY ON THURSDAY
MORNING BUT WILL STILL SEE LOW CLOUDS FOR COASTS AND NEARBY
VALLEYS TO START THE DAY. BY FRIDAY MORNING THE MARINE LAYER
SHRINKS EVEN MORE AND MAY ONLY SEE PATCHY CLOUDS SOUTH OF PT
CONCEPTION. TEMPERATURES WILL START TO REBOUND LATE IN THE WEEK
BUT A LARGE SCALE UPPER TROUGH ACROSS MOST OF THE WEST WILL SLOW
ANY SIGNIFICANT WARMING UNTIL LATER IN THE WEEKEND.
LONG TERM...HIGH PRESSURE SLOWLY BUILDS ACROSS THE SOUTHWEST OVER
THE WEEKEND WITH TEMPERATURES WARMING AND THE MARINE LAYER
BECOMING LESS OF AN ISSUE FOR COASTAL AREAS. VERY LITTLE
SIGNIFICANT WEATHER ISSUES THROUGH TUESDAY. REMNANT MOISTURE FROM
TWO TROPICAL SYSTEMS (LOWELL AND KARINA) COULD GET PULLED
NORTHWARD CLOSER TO SOUTHERN CALI BY MONDAY OR TUESDAY. WOULD ONLY
EXPECT SOME MID TO HIGH LEVEL CLOUDS FROM THESE SYSTEMS AT BEST
WITH LITTLE EFFECT ON TEMPERATURES.
&&
.AVIATION...19/2320Z.
UPPER LOW NEAR POINT CONCEPTION WILL CONTINUE TO MAINTAIN A DEEP MARINE
LAYER THROUGH PERIOD...RISING TO AROUND 4000 FEET ACROSS AREAS SOUTH OF
POINT CONCEPTION BY WEDNESDAY MORNING. EXPECTING MVFR CIGS TO BE
MORE WIDESPREAD ACROSS COASTAL/VALLEY TAF LOCATIONS TONIGHT...WITH LOWEST
CONFIDENCE IN TIMING ACROSS LA COUNTY. THERE IS A CHANCE OF DRIZZLE
OVERNIGHT ACROSS COASTAL/VALLEY LOCATIONS. THEN ON WEDNESDAY...THERE
WILL BE A 20 PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS FOR ALL OF
LA COUNTY AS WELL AS THE VENTURA COUNTY MOUNTAINS.
KLAX AND KBUR...POOR CONFIDENCE IN ARRIVAL TIME OF MVFR CIGS
TONIGHT. IF LOW CLOUDS DEVELOP...THERE WILL BE A CHANCE OF DRIZZLE
OVERNIGHT. AS LOW DRAWS CLOSER...THERE WILL BE A 20 PERCENT CHANCE
OF SHOWERS AND THUNDERSTORMS ON WEDNESDAY.
&&
.MARINE...19/900 PM.
TIMING FOR CHANCES FOR SHOWERS AND THUNDERSTORMS HAS BEEN BUMPED
TO AN EARLIER TIME FRAME. SHOWERS AND THUNDERSTORMS COULD DEVELOP
ACROSS THE SOUTHERN WATERS AFTER MIDNIGHT TONIGHT. GUSTY AND
ERRATIC WINDS...CHOPPY SEAS...SMALL HAIL...AND DANGEROUS CLOUD-TO-
OCEAN LIGHTNING ARE POSSIBLE AFTER MIDNIGHT TONIGHT AND THROUGH
WEDNESDAY MORNING. OTHERWISE...WINDS AND SEAS WILL REMAIN BELOW
SMALL CRAFT ADVISORY LEVELS.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWWLOX).
&&
$$
PUBLIC...HALL/BOLDT
AVIATION...GOMBERG
MARINE...HALL
SYNOPSIS...SETO/HALL
WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
937 AM PDT Mon Aug 18 2014
.Synopsis...
Cooler temperatures with a slight chance of mountain thunderstorms
next few days.
.Discussion...
Forecast on track this morning. Instability expected in northern
higher terrain today and also down south into highest elevations
of western Tehama and Glen county. But expecting the most
impactful activity to really remain north and west of Sacramento
forecast area. We have expanded the coverage of isolated
thunderstorms a bit to match this thinking. With light to
southeast steering flow...activity that does fire should remain on
the crest areas and drift into Eureka area late this afternoon. We
are messaging this best we can in FWF product. Supporting this
though are all the HiRes models...which HRRR seems to be a little
underdone but ARW/NMM HiRes models showing isolated coverage in
these areas.
.Previous Discussion...
Clear skies across interior NorCal early this morning with
temperatures and surface pressure gradients nearly identical to
24 hours ago. Marine layer remains under 1500 ft in depth at Ft
Ord, but satellite imagery shows a little more stratus in the east
Bay into western portions of the Carquinez Strait.
Weak upper low now along the central Oregon coast is forecast to
drop southward off the NorCal coast early this week before ending
up vicinity SoCal by mid-week. A few thunderstorms developed
Sunday afternoon and evening across far northern California, and
it is expected that a few storms will develop again later this
afternoon and evening further south into northern Shasta County
and the northern Coast Range. This same area may see a few storms
again on Tuesday afternoon/evening with perhaps a few storms in
the Sierra to the south of Lake Tahoe as well.
Temperatures are forecast to cool a bit the next couple of days as
the low passes to our west resulting in a little synoptic cooling
and stronger onshore flow as the marine layer deepens a bit. More
settled weather returns to the mountains by mid-week as the low
shifts south. Temperatures are forecast to remain around normal
through next weekend as a weak trough over the interior West
maintains onshore flow.
&&
.Extended Discussion (Friday through Monday)
Medium-range models continue to struggle with the evolution of the
cutoff low beyond Wednesday. The GFS weakens the system and
eventually phases it in with a Pacific Northwest trough late this
week. The ECMWF and GEM keep the low stronger off the Baja
California coast, and eventually retrograde it westward as high
pressure builds over the Desert Southwest. Both solutions are dry
for Northern California, but the EC and GEM would be substantially
warmer than what the GFS shows. Our forecast is a blend of the
two very different solutions, with hopes of improving model
consensus soon.
Dang
&&
.Aviation...
VFR conditions the next 24 hours across interior Northern
California, except local IFR conditions west of KSUU early
this morning. Winds will remain below 12 kt across Valley TAF
sites, with local SW winds 10-20 kt near the Delta and over higher
elevations. Dang/JBB
&&
.STO Watches/Warnings/Advisories...
None.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
335 PM MDT MON AUG 18 2014
.SHORT TERM...(TONIGHT THROUGH TUESDAY NIGHT)
ISSUED AT 333 PM MDT MON AUG 18 2014
BIG CHANGES WILL OCCUR OVER THE NEXT 24 HOURS AS AN UNSEASONABLY
STRONG AND NEARLY VERTICALLY STACKED TROUGH...CURRENTLY OVER
CALIFORNIA...MOVES EAST INTO THE GREAT BASIN. THIS BRINGS EASTERN
UTAH AND WESTERN COLORADO INTO IDEAL POSITION FOR DEEP
SUBTROPICAL MOISTURE TO ADVECT INTO THE REGION. PRECIPITABLE
WATER VALUES OF 1 TO 1.3 INCH ARE EXPECTED TO COVER EASTERN UTAH
AND EVEN EXTREME WESTERN COLORADO BY LATE TUESDAY AFTERNOON. THIS
IS ALMOST 2 STANDARD DEVIATIONS ABOVE NORMAL FOR THIS TIME OF
YEAR.
MODELS ARE FORECASTING MULTIPLE VORT MAXES TO REACH THE UT/CO
BORDER THROUGHOUT THE DAY FROM NOON TO MIDNIGHT. THERE IS SOME
UNCERTAINTY ON THE TIMING OF H3 JET SUPPORT OF 60KTS REACHING THE
AREA...WHICH WILL HELP TO PROVIDE ASCENT IN THE UNIMPRESSIVE CAPE
AND SHEAR ENVIRONMENT. EXPECTING CLOUD COVER TO HINDER INSTABILITY
DURING THE DAY...HOWEVER THIS SCENARIO COULD CHANGE IF SUFFICIENT
CLEAR AIR IS ABOUND BY LATE MORNING. THE RAP SHOWS JET SUPPORT
INCHING INTO EASTERN UTAH AND SOUTHWEST COLORADO DURING THE
MORNING ON TUESDAY...HOWEVER THE NAM AND GFS SHOW THE BEST JET
SUPPORT ON TUESDAY NIGHT AND WEDNESDAY MORNING. STORM MOTION WILL
BE DECENT FOR TUESDAY - ABOUT 20 TO 30 KTS...SO COULD NOT JUSTIFY
A FLASH FLOOD WATCH AT THIS TIME. IT WILL RAIN IN MANY LOCATIONS
BY TUESDAY NIGHT...BUT ONLY EXPECTING MODERATE TO HEAVY RAIN
MULTICELLULAR STORMS CAUSING NUISANCE/SMALL STREAM FLOODING AT
THIS TIME. SEE HYDRO SECTION FOR MORE.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 333 PM MDT MON AUG 18 2014
THE FORECAST AREA REMAINS UNDER SW FLOW WED-THU WITH THE JET AXIS
OVERHEAD. MONSOONAL MOISTURE PLUME WEAKENS WITH PRECIPITABLE WATER
VALUES DROPPING UNDER 1 INCH. NAM/GFS SHOW A WEAK 300 MB JET MAX
ARRIVING ON WED FOR POTENTIAL SUPPORT AND INCREASED VERTICAL
SHEAR....AND SHOULD IT ENTRAIN SOME DRIER MIDLEVEL AIR OVER HIGHER
MOISTURE NEAR THE SURFACE...IT COULD LEAD TO SOME STRONGER STORMS
WED AFTERNOON.
MODELS STILL HAVING TROUBLE HANDLING THE UPPER LOW THAT IS
CURRENTLY DROPPING SOUTH ALONG THE NRN CA COAST...WHICH LOWERS
FORECAST CONFIDENCE AFTER MIDWEEK. BUT AT LEAST THE GFS AND ECWMF
NOW BOTH BRING THE 500 MB LOW INLAND...JUST TIMING AND TRACK ARE
DIFFERENT. THE 12Z GFS SWINGS THE LOW INLAND ACROSS SRN CA WED AND
THEN LIFTS IT NE ACROSS UT AS AN OPEN WAVE ON THU. THIS COULD ADD
SOME DYNAMIC PUNCH TO STORM DEVELOPMENT ON THU. THE 12Z ECMWF IS
SLOWER BRINGING IT INLAND AND TRACKS IT FARTHER SOUTH ACROSS AZ
AND NWRN NM. THE 12Z CANADIAN HAS IT SHEARING OUT ALONG THE SRN CA
COAST THU-FRI. MODELS ALSO SHOW ENERGY DROPPING OUT OF THE GULF OF
AK LATE IN THE WEEK THAT SHOULD MAINTAIN TROUGHING OVER THE PAC
NW/NRN ROCKIES.
FOR NOW...WITH FOLLOW THE CONSENSUS MODEL TREND...WHICH SHOWS A
LESSENING OF STORM COVERAGE THE LAST HALF OF THE WEEK BUT NOT A
COMPLETE CESSATION. LOWER LEVEL MOISTURE LIKELY TO LINGER WITH SOME
SMALLER EMBEDDED WAVES IN THE FLOW THAT COULD TRIGGER ISOLATED-
SCATTERED ACTIVITY ABOUT EACH DAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1108 AM MDT MON AUG 18 2014
A LINE OF -SHRA SOUTH OF KCAG BUT NORTH OF THE BOOKCLIFFS
CONTINUES TO MOVE EAST THROUGH THE AREA THANKS TO A WEAK WEATHER
DISTURBANCE ACROSS NORTHERN COLORADO. ISOLATED -RA/-TSRA WILL
INCREASE IN COVERAGE OVER THE MOUNTAINS AROUND 18Z. KEGE AND KASE
HAVE A SLIGHT CHANCE OF RECEIVING A SHOWER OR THUNDERSTORM TODAY.
MOISTURE WILL INCREASE AFTER 12Z TUESDAY MORNING FROM THE
SOUTHWEST AND INCREASE THE COVERAGE OF RAIN SHOWERS AND
THUNDERSTORMS BY 18Z TUESDAY.
&&
.HYDROLOGY...
ISSUED AT 333 PM MDT MON AUG 18 2014
MONSOONAL MOISTURE WILL RETURN TOMORROW AS AN UPPER LEVEL LOW OVER
CALIFORNIA PULLS DEEP SUBTROPICAL MOISTURE INTO THE REGION.
SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE FROM WEST TO
EAST THOUGHOUT THE AFTERNOON AND PEAK DURING THE LATE HOURS OF THE
DAY AND OVERNIGHT INTO WEDNESDAY MORNING. EXPECTING TO HAVE SMALL
STREAM AND ARROYO FLOOD ISSUES BY WEDNESDAY MORNING IN THE USUAL
PROBLEM AREAS...BUT AT THIS NOT EXPECTING HIGH COVERAGE OF
TORRENTIAL DOWNPOURS DUE TO THUNDERSTORMS. THEREFORE...NO WATCHES
HAVE BEEN ISSUED AT THIS TIME.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...JAM
LONG TERM...JAD
AVIATION...JAM
HYDROLOGY...JAM
AREA FORECAST DISCUSSION
NWS PUEBLO CO
322 PM MDT MON AUG 18 2014
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 259 PM MDT MON AUG 18 2014
THE UPR RIDGE IS STILL CENTERED NR THE FOUR CORNERS AREA TODAY
AND PRECIPITABLE WATER VALUES ARE SIMILAR TO WHAT THEY WERE
YESTERDAY. ISOLATED SHOWERS AND TSTMS HAVE DEVELOPED OVR SOME OF
THE MOUNTAIN AREAS AS OF 1930Z. SHOULD SEE COVERAGE OVR THE MTNS
INCREASE THIS AFTERNOON. HRRR AND RAP SHOW PCPN DEVELOPING/MOVING
OVR THE SERN PLAINS AND PORTIONS OF THE SAN LUIS VALLEY LATER THIS
AFTERNOON AND THIS EVENING. THE HRRR AND RAP HAVE PCPN ENDING IN
MOST LOCATIONS BY LATE EVENING...BUT SHOW THE POTENTIAL FOR SOME
CONTINUING OVR THE SAN JUAN MTNS INTO THE LATE NIGHT HOURS.
AS AN UPR TROF DIGS INTO SRN CA TONIGHT AND TUESDAY...THE UPR RIDGE
OVR OUR AREA SHIFTS EASTWARD. THIS PUSHES A LITTLE BETTER MSTR INTO
WRN CO FOR TUE...WITH PRECIPITABLE WATER VALUES INCREASING SLIGHTLY
OVR THE CONTDVD. AS A RESULT THERE SHOULD BE MORE WIDESPREAD SHOWER
AND TSTM ACTIVITY ALONG THE CONTDVD TOMORROW. THE ERN MTNS WL
LIKELY SEE SCT PCPN DEVELOPING IN THE AFTERNOON HOURS...WHILE THE
SERN PLAINS SHOULD JUST SEE A FEW SHOWERS OR STORMS DEVELOP. HIGH
TEMPS ON TUE SHOULD BE 5-8 DEGREES ABOVE AVERAGE OVR THE SERN
PLAINS...AND AROUND NORMAL IN THE SAN LUIS VALLEY AND UPR ARKANSAS
RIVER VALLEY.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 259 PM MDT MON AUG 18 2014
...ACTIVE WEATHER FOR AT LEAST THE NEXT WEEK...
MODELS ARE NOW IN REASONABLE AGREEMENT THAT THE CUTOFF LOW
OFF THE CA COAST WILL PHASE WITH THE TROUGH MOVING INTO THE
PACNW...AND THIS WILL LEAD TO AN ENHANCED MONSOONAL PATTERN
FOR THE LATTER PART OF THIS WEEK AND BEYOND. A COUPLE OF
ADDITIONAL SHORTWAVES WILL MOVE THROUGH THE LONGWAVE TROUGH
PATTERN THAT IS OVER WRN CANADA...BRINGING THE THREAT FOR PERIODS
OF HEAVY RAIN TO OUR AREA.
TUE NIGHT...EXPECT ISOLD STORMS TO PERSIST OVER THE CONTDVD
AS THE PLUME BEGINS TO MOVE OVR WRN CO. BY LATE WED THE TROUGH
AND ABSORBED CUTOFF WILL MOVE INTO NW AZ/SW UT...AND THE THREAT
OF HEAVY BANDS OF CONVECTION WILL CONTINUE FOR THE SW MTS AND
CONTDVD. DEPENDING ON WHAT HAS ALREADY FALLEN OVR THE MTS
WE COULD SEE THE THREAT OF MORE FLASH FLOODING AND RISK OF
SLIDES FOR THE MT AREAS. TIMING FOR OUR CWA`S STAGES IN THE
PRO CYCLING CHALLENGE DOES NOT LOOK FAVORABLE AS THE STRONGEST
DYNAMICS FROM THIS SYSTEM MOVE THROUGH ON THURSDAY. THAT IS WHEN
THE CORE OF A 100 KT JET STREAK MOVES THROUGH CO. THIS IS PRETTY
ROBUST FOR AN AUGUST SYSTEM. WITH H6 TEMPS AT MINUS 2C OR LOWER IN
THE CORE OF THE LOW...COULD EASILY SEE SOME SNOW FOR ELEVS ABOVE
12K FEET BY FRI MORNING. THE GFS BRINGS US A BIT OF A BREAK IN THE
ACTION ON SATURDAY BEFORE ANOTHER FRONT COMES THROUGH SAT
NIGHT...FOLLOWED BY A THIRD SYSTEM SUN OR MON. THE ECMWF HAS SOME
OF THE HEAVIEST QPF ON FRI AND CONTINUES THE ONSLAUGHT THROUGH THE
WEEKEND. A BIT HARD TO SAY WHEN THE HEAVIEST RAIN WILL FALL...BUT
THE THREAT OF HEAVY PRECIP WILL CERTAINLY BE WITH US SO LONG AS
THIS PARADE OF SHORTWAVES CONTINUE...AT LEAST THROUGH THE FIRST
DAYS OF NEXT WEEK. ENSEMBLE POPS LOOKED MUCH TOO LOW SO HAVE
RAISED POPS BY AT LEAST 10 PERCENT OVER THIS TIME FRAME FOR BOTH
THE PLAINS AND MTS...WHILE THE MTS WILL SEE THE BEST SHOT AT HEAVY
PRECIP. TEMPS WILL TREND DOWNWARD THROUGH THE PERIOD...STARTING IN
THE NR 90 RANGE FOR TUE-THU...AND THEN FALLING INTO THE 80S AND
POSSIBLY LOWER FOR THE PLAINS NEXT WEEKEND. LOOKS LIKE THE
FORECAST WILL REMAIN CHALLENGING FOR THE REST OF THIS MONTH. ROSE
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 259 PM MDT MON AUG 18 2014
VFR CONDITIONS ARE EXPECTED AT KCOS...KPUB AND KALS TONIGHT THROUGH
TUESDAY AFTERNOON. TSTMS COULD MOVE INTO THE VCNTY OF THE TERMINAL
SITES THIS EVENING...WITH KCOS SEEING THE BEST CHANCE OF THIS
OCCURRING. SHOWERS AND TSTMS WL AGAIN DEVELOP OVR THE MOUNTAINS AND
THEN SPREAD OVR SOME OF THE LOWER ELEVATIONS...POSSIBLY MOVING IN
THE VCNTY OF THE TERMINAL SITE.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...28
LONG TERM...ROSE
AVIATION...28
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1101 PM MDT SUN AUG 17 2014
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 252 PM MDT SUN AUG 17 2014
AN UPR RIDGE WL REMAIN CENTERED NR THE FOUR CORNERS THRU
TONIGHT...SHIFTING A LITTLE EASTWARD ON MON. THIS AFTERNOON A WEAK
DISTURBANCE IS MOVING ACRS NRN CO. SOME ISOLD THUNDERSTORMS HAVE
DEVELOPED OVR SOME OF THE MTN AREAS AND OVER THE EAST CENTRAL
PLAINS. EXPECTING MORE DEVELOPMENT OVR THE MTNS THE REST OF THIS
AFTERNOON...WITH SOME ISOLD DEVELOPMENT OVR PORTIONS OF THE SERN
PLAINS. BOTH THE RAP AND HRRR CONTINUE TO SHOW AN AREA OF TSTMS
DEVELOPING THIS AFTERNOON...ASSOCIATED WITH THE WX DISTURBANCE...
OVER THE PIKES PEAK REGION AND THEN MOVING SOUTHEASTWARD ACRS THE
SERN PLAINS THRU THE EVENING HOURS...AND DISSIPATING OR EXITING
THE SERN CORNER OF THE STATE BY ABOUT 1 OR 2 AM.
ON MONDAY AN UPR TROF MOVES INTO WRN NV AND SHIFT THE UPR RIDGE
CENTER A LITTLE EASTWARD OVR CO. PRECIPITABLE WATER VALUES ACRS THE
FORECAST AREA ARE EXPECTED TO BE SIMILAR TO TODAY. EXPECTING SOME
SHOWERS/TSTM DEVELOPMENT OVR SOME OF THE MTN AREAS IN THE LATE
MORNING HOURS AGAIN. THEN INCREASING IN COVERAGE IN THE AFTERNOON
HOURS OVER THE MTNS AND HIGH VALLEYS...WITH SOME ISOLD STORMS
DEVELOPING OVR MOVING OVR THE SOUTHEAST PLAINS. HIGH TEMPS ON MON
WL AGAIN BE ABOVE AVERAGE BY AROUND 5 DEGREES.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 252 PM MDT SUN AUG 17 2014
...MORE MONSOON NEXT WEEK...
EXTENDED FORECAST CONTINUES TO BE A BIT SHAKY AS THE GLOBAL
MODEL RUNS STRUGGLE WITH FAIRLY COMPLEX INTERACTIONS INVOLVING
THE POLAR JET TO THE NORTH AND A SUBTROPICAL INFLUENCE TO THE
SOUTH. THE EC AND GFS ARE IN REASONABLE AGREEMENT THROUGH ABOUT
TUESDAY...THEN THE CONSISTENCY STARTS TO UNRAVEL.
A PACIFIC TROUGH WILL AMPLIFY ON TUESDAY AND BEGIN MOVING INTO
THE PACNW...AS A CUTOFF LOW DRIFTS OFF THE CA COAST. INCREASED
S-SW FLOW ALOFT WILL BRING MOISTURE UP FROM MEXICO AND THE DESERT
SW INTO WRN CO. THE ECMWF SEEMS TO BE OVERDOING QPF E OF THE
MTS...WHILE THE GFS AND NAM ARE MORE REALISTIC IN DEPICTING
MOSTLY DRY CONDITIONS FOR THE PLAINS BUT PLENTY OF MOISTURE
FOR THE MTN AREAS. TEMPS WILL START TO MODERATE FOR MOST OF OUR
CWA AND SHOULD BE CLOSE TO AVERAGE.
THE LATEST GFS HAS A STRONGER OR MORE AMPLIFIED NRN TROUGH...AND
ALSO SHOWS BETTER PHASING WITH THE CA CUT-OFF LOW. IT ALSO HINTS
AT AT LEAST A POTENTIAL MOISTURE TAP FROM A TROPICAL SYSTEM THAT
WILL BE MOVING NWD...WELL OFF OF THE BAJA PENINSULA. THE EC HAS A
WEAKER NRN SYSTEM AND RETROGRADES THE UPPER LOW AND TROPICAL
SYSTEM OFF THE CA COAST...WITH LESS OF A MOISTURE FLUX INTO CO.
BASED ON THE PATTERN AND ENSEMBLE TRENDS...IT APPEARS LIKELY THAT
AN AMPLIFIED PACIFIC SYSTEM WILL MOVE INTO THE NRN ROCKIES FOR THE
LATTER PART OF NEXT WEEK INTO NEXT WEEKEND. HAVE BOOSTED POPS FROM
WED ONWARD BY 5-10 PERCENT TO ACCOUNT FOR THAT LIKELIHOOD...AND
LATER SHIFTS MAY HAVE TO CONTINUE THAT TREND IF THE DEEPER SYSTEM
ENDS UP LOOKING MORE LIKELY. WILL HAVE TO KEEP A CLOSE EYE ON
TRENDS...SINCE THE LONG RANGE GFS HINTS AT SIGNIFICANT RAINFALL
POSSIBLE ON THE BACKSIDE OF THIS NRN BRANCH SYSTEM...BY THE LAST
WEEK IN AUGUST. ROSE
&&
.AVIATION...ISSUED AT 1101 PM MDT SUN AUG 17 2014
THE KALS...KCOS AND KPUB TAF SITES SHOULD EXPERIENCE VFR
CONDITIONS THROUGH TONIGHT.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
147 PM EDT MON AUG 18 2014
.SYNOPSIS...
A FRONTAL BOUNDARY WILL STALL OVER VIRGINIA TODAY. A WAVE OF LOW
PRESSURE WILL TRACK EASTWARD ALONG THE STALLED BOUNDARY TONIGHT
BEFORE MOVING OFFSHORE TUESDAY. THE FRONTAL BOUNDARY SHOULD REMAIN
NEARLY STATIONARY FROM THE GREAT LAKES TO THE SOUTHERN MID-ATLANTIC
STATES WEDNESDAY AND THURSDAY WHILE A SERIES OF DISTURBANCES RIDE
ALONG IT. THE FRONT WILL GRADUALLY SHIFT FARTHER SOUTH AND WEST OF
THE AREA FRIDAY AND THIS WEEKEND AS HIGH PRESSURE WEDGES DOWN FROM
EASTERN CANADA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATEST WATER VAPOR AND 11-3.9 IR SHOW THE QUASI-STATIONARY FRONTAL
BOUNDARY TO OUR SOUTH EXTENDING NORTHEAST INTO THE MARYLAND/WEST
VIRGINIA PANHANDLE. DRY AIR WILL CONTINUE TO PRESS INTO THE REGION
FROM THE NORTH THROUGH THE MORNING HOURS UNDER A LIGHT NORTHERLY
FLOW. WINDS ARE EXPECTED TO VEER TOWARDS THE WEST-SOUTHWEST LATER
THIS AFTERNOON AS THE FRONT WAVERS TO OUR SOUTH. A WEAK SURFACE LOW,
CURRENTLY ACROSS THE MID-WEST, WILL RIDE ALONG THIS FRONTAL BOUNDARY
LATER THIS AFTERNOON..STAYING TO THE SOUTH OF OUR CWA. BASED ON
THE LATEST RAP AND HRRR WITH THE 12:30 PM UPDATE, PUSHED BACK ANY
RAIN CHANCE TILL TONIGHT ACROSS THE SOUTHERN DELMARVA.
ELSEWHERE, THE LOWER PWAT AIR IN PLACE WILL TAKE A WHILE TO
MODIFY SO WE EXPECT A DRY DAY WITH SOME INCREASING CLOUD COVER
LATE IN THE DAY. TEMPERATURES WILL RUN CLOSE TO NORMAL TODAY, LIKE
THE PAST FEW DAYS. DID MAKE SOME MINOR ADJUSTMENTS ON THE
TEMPERATURES WITH THE 12;30 PM UPDATE BASED ON THE 16Z METARS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
THE SURFACE WAVE ALONG THE FRONTAL BOUNDARY WILL PASS TO OUR SOUTH
LATE TONIGHT. THIS SYSTEM OVER THE PAST SEVERAL DAYS HAS TRENDED
TOWARDS A MORE SUPPRESSED, FASTER WEST-EAST MOVEMENT, AND A
SOUTHEASTERN TRACK THAT WOULD ALLOW FOR LESS SIGNIFICANT RAINFALL
THREAT THEN PREVIOUSLY THOUGHT...WE REMOVED THE MENTION FROM THE HWO
AT THIS TIME.
SURFACE FLOW BEGINS TO VEER TOWARDS THE EAST-SOUTHEAST BY THIS
EVENING BRINGING MORE LOW-LEVEL INTO THE REGION...EVERYWHERE. NOT
EXPECTING MUCH IN THE WAY OF RAIN CHANCES LATE TONIGHT, OUTSIDE OF
THE DELMARVA, WITHOUT MUCH SYNOPTIC SCALE LIFT AND DON`T THINK THE
SURFACE FLOW IS STRONG ENOUGH FOR UPGLIDE ACROSS OUR WESTERN ZONES,
SO WE STAY MOSTLY DRY TONIGHT. TEMPERATURES, UNDER INCREASINGLY
CLOUDY SKIES, WILL BE SEVERAL DEGREES WARMER THAN THE PAST FEW
MORNINGS...BLEND OF THE MET/MAV LOOKS GOOD.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
WHILE OPPRESSIVE HEAT WILL BUILD ACROSS THE SOUTHERN CONUS IN
ASSOCIATION WITH A STRENGTHENING ANTICYCLONE THIS WEEK, IT IS NOT
EXPECTED TO REACH OUR AREA THROUGH THE NEXT 7 DAYS AS THE REGION
WILL GENERALLY BE UNDER THE PRESENCE OF MEAN TROUGHING AND ONSHORE
FLOW AT THE SFC. TEMPS THRU THE PERIOD SHOULD BE NEAR TO SLIGHTLY
BELOW NORMAL FOR THIS TIME OF YEAR.
LOPRES IS EXPECTED TO MOVE OFF THE SOUTHEAST VA COAST TUESDAY
MORNING. MODELS CONTINUE THE TREND TOWARD A WEAKER, MORE PROGRESSIVE
SYSTEM, WHICH WILL RESULT IN A EARLIER END TO THE SHOWERS ACROSS THE
DELMARVA DURING THE MORNING. THERE MAY ALSO BE AN ISOLATED SHOWER
THAT DEVELOPS ACROSS THE HIGHER ELEVATIONS OF PA LATE IN THE DAY,
BUT THE BULK OF DIURNAL CONVECTION SHOULD BE CENTERED CLOSER TO THE
SHARPENING LLVL THETA-E RIDGE, WHICH WILL RESIDE WEST OF THE AREA.
OTHERWISE, DRY CONDITIONS PREVAIL. FCST MAX TEMPS RANGING FROM THE
MID 70S IN THE POCONOS TO MID 80S ALONG THE I-95 CORRIDOR ARE CLOSE
TO CLIMO.
A WEAK RIDGE OF HIPRES BECOMES ESTABLISHED ACROSS THE COASTAL MID
ATLANTIC TUESDAY NIGHT AND WEDNESDAY MORNING. ALTHOUGH MODEL
GUIDANCE HASN`T JUMPED ON IT YET, WILL HAVE TO WATCH FOR THE
POTENTIAL FOR FOG OR STRATUS DEVELOPMENT AS PERSISTENT ONSHORE FLOW
IN THE BOUNDARY LAYER DRAWS MARINE AIR INLAND.
THE NEXT SYSTEM TO IMPACT THE AREA WILL BE A WAVE OF LOPRES OVER THE
GREAT LAKES THAT MOVES SOUTHEASTWARD ALONG THE STALLED FRONTAL
BOUNDARY IN THE MID-ATLANTIC STATES WEDNESDAY AFTERNOON THROUGH
THURSDAY. THE DISTURBANCE IS ALSO FORECAST TO WEAKEN AS THE UPPER
LOW BECOMES AN OPEN WAVE BY THE TIME IT REACHES OUR AREA. THIS LOW
OF PAC NW ORIGIN IS NOT EXPECTED TO TAP INTO APPRECIABLE GULF OF
MEXICO MOISTURE DURING ITS CROSS-COUNTRY TREK. ACCORDINGLY, THE SETUP
DOES NOT PARTICULARLY SUPPORT A HEAVY RAINFALL EVENT OR A WASHOUT,
BUT THERE IS STILL A CHANCE FOR SHOWERS AND THUNDERSTORMS DURING THE
SECOND HALF OF THE WORK WEEK. CHANCE POPS INITIALLY CONFINED TO WEST
OF I-95 WEDNESDAY AFTERNOON, BEFORE THIS ACTIVITY WOULD TRY TO
ADVANCE EASTWARD INTO THE REST OF THE CWA WEDNESDAY NIGHT. POPS
THURSDAY HIGHEST CLOSER TO THE STATIONARY BOUNDARY OVER THE
DELMARVA/NORTHEAST MD/SOUTHEAST PA.
A RIDGE OF HIPRES OVER EASTERN CANADA IS EXPECTED TO NOSE DOWN INTO
THE FORECAST AREA FRIDAY THROUGH THE WEEKEND. MODELS NOW SHOW THE
HIGH BECOMING ESTABLISHED ALONG THE EASTERN SEABOARD SOONER THAN
PREVIOUS GUIDANCE HAD INDICATED. TRENDED TOWARD A DRIER FORECAST
FRIDAY INTO THE WEEKEND AS THE HIGH SHOULD ACT TO SHIFT THE OLD
FRONTAL BOUNDARY AND STORM TRACK SOUTH AND WEST OF THE AREA. ONSHORE
FLOW WOULD POSITION THE REGION IN COOLER, MORE STABLE AIRMASS
REGIME.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
SCATTERED MID LEVEL CLOUDS WILL CONTINUE TO MOVE EAST INTO THE
REGION AHEAD OF A LOW PRESSURE SYSTEM PASSING TO OUR SOUTH THIS
AFTERNOON. CEILINGS MAY LOWER TO AROUND 5000 FEET WITH THIS CLOUD
COVER TONIGHT. PRECIPITATION LOOKS TO REMAIN SOUTH OF ALL TAF SITES.
THE CLOUDS SHOULD BREAK UP AND BECOME MORE SCATTERED BY TOMORROW
AFTERNOON. WINDS WILL BE VARIABLE THIS AFTERNOON WITH SOME
UNCERTAINTY IN THE WIND DIRECTION BUT WINDS SHOULD REMAIN UNDER
10 KNOTS. A SLIGHT CHANCE FOR AN ISOLATED WIND GUST IS PRESENT THROUGH
LATE AFTERNOON BUT SMALL ENOUGH NOT TO INCLUDE IN THE TAFS ATTM. LIGHT
AND VARIABLE WINDS SHOULD TURN MORE OUT THE EAST ON TUESDAY AND
REMAIN UNDER 10 KNOTS.
OUTLOOK...
TUESDAY NIGHT THROUGH WEDNESDAY MORNING...STRATUS OR FOG
POSSIBLE AS ONSHORE FLOW DEVELOPS. BEST SETUP WOULD BE CLOSER TO
THE COAST (ACY/MIV).
WEDNESDAY AFTERNOON THROUGH THURSDAY NIGHT...CHANCE FOR SHRA/TSRA AS
A SERIES OF DISTURBANCES MOVE THRU THE REGION. LOCAL/TEMPORARY
FLIGHT RESTRICTIONS POSSIBLE.
FRIDAY...VFR CONDITIONS.
&&
.MARINE...
WE CONTINUE THE TRANQUIL SUB-SCA CONDITIONS TODAY AND TONIGHT. LIGHT
NORTHERLY WINDS WILL BACK TOWARDS THE SOUTH-SOUTHEAST DURING THE
COURSE OF THE DAY, AND REMAIN BELOW 10 KNOTS. SEAS WILL CONTINUE TO
RUN AROUND 2 TO 3 FEET. WINDS THEN VEER TOWARDS THE EAST LATE
TONIGHT AS A WEAK SURFACE LOW PRESSURE SLIDES EASTWARD TO OUR
SOUTH.
OUTLOOK...
TUESDAY...LOPRES MOVES OFF THE VA COAST. A TIGHT PRESSURE GRADIENT
TO THE NORTH OF THE LOW MAY PRODUCE EASTERLY WINDS 15-20 KT. SCA
POTENTIAL LOW.
WEDNESDAY THROUGH THURSDAY...ONSHORE FLOW CONTINUES BUT WILL WEAKEN
OVER TIME. TSRA POSSIBLE IN SOUTHERN WATERS ON THURSDAY.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KLEIN
NEAR TERM...GAINES/HEAVENER
SHORT TERM...HEAVENER
LONG TERM...KLEIN
AVIATION...GAINES/HEAVENER/KLEIN
MARINE...HEAVENER/KLEIN
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
1224 PM EDT MON AUG 18 2014
.SYNOPSIS...
A FRONTAL BOUNDARY WILL STALL OVER VIRGINIA TODAY. A WAVE OF LOW
PRESSURE WILL TRACK EASTWARD ALONG THE STALLED BOUNDARY TONIGHT
BEFORE MOVING OFFSHORE TUESDAY. THE FRONTAL BOUNDARY SHOULD REMAIN
NEARLY STATIONARY FROM THE GREAT LAKES TO THE SOUTHERN MID-ATLANTIC
STATES WEDNESDAY AND THURSDAY WHILE A SERIES OF DISTURBANCES RIDE
ALONG IT. THE FRONT WILL GRADUALLY SHIFT FARTHER SOUTH AND WEST OF
THE AREA FRIDAY AND THIS WEEKEND AS HIGH PRESSURE WEDGES DOWN FROM
EASTERN CANADA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATEST WATER VAPOR AND 11-3.9 IR SHOW THE QUASI-STATIONARY FRONTAL
BOUNDARY TO OUR SOUTH EXTENDING NORTHEAST INTO THE MARYLAND/WEST
VIRGINIA PANHANDLE. DRY AIR WILL CONTINUE TO PRESS INTO THE REGION
FROM THE NORTH THROUGH THE MORNING HOURS UNDER A LIGHT NORTHERLY
FLOW. WINDS ARE EXPECTED TO VEER TOWARDS THE WEST-SOUTHWEST LATER
THIS AFTERNOON AS THE FRONT WAVERS TO OUR SOUTH. A WEAK SURFACE LOW,
CURRENTLY ACROSS THE MID-WEST, WILL RIDE ALONG THIS FRONTAL BOUNDARY
LATER THIS AFTERNOON..STAYING TO THE SOUTH OF OUR CWA. BASED ON
THE LATEST RAP AND HRRR WITH THE 12:30 PM UPDATE, PUSHED BACK ANY
RAIN CHANCE TILL TONIGHT ACROSS THE SOUTHERN DELMARVA.
ELSEWHERE, THE LOWER PWAT AIR IN PLACE WILL TAKE A WHILE TO
MODIFY SO WE EXPECT A DRY DAY WITH SOME INCREASING CLOUD COVER
LATE IN THE DAY. TEMPERATURES WILL RUN CLOSE TO NORMAL TODAY, LIKE
THE PAST FEW DAYS. DID MAKE SOME MINOR ADJUSTMENTS ON THE
TEMPERATURES WITH THE 12;30 PM UPDATE BASED ON THE 16Z METARS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
THE SURFACE WAVE ALONG THE FRONTAL BOUNDARY WILL PASS TO OUR SOUTH
LATE TONIGHT. THIS SYSTEM OVER THE PAST SEVERAL DAYS HAS TRENDED
TOWARDS A MORE SUPPRESSED, FASTER WEST-EAST MOVEMENT, AND A
SOUTHEASTERN TRACK THAT WOULD ALLOW FOR LESS SIGNIFICANT RAINFALL
THREAT THEN PREVIOUSLY THOUGHT...WE REMOVED THE MENTION FROM THE HWO
AT THIS TIME.
SURFACE FLOW BEGINS TO VEER TOWARDS THE EAST-SOUTHEAST BY THIS
EVENING BRINGING MORE LOW-LEVEL INTO THE REGION...EVERYWHERE. NOT
EXPECTING MUCH IN THE WAY OF RAIN CHANCES LATE TONIGHT, OUTSIDE OF
THE DELMARVA, WITHOUT MUCH SYNOPTIC SCALE LIFT AND DON`T THINK THE
SURFACE FLOW IS STRONG ENOUGH FOR UPGLIDE ACROSS OUR WESTERN ZONES,
SO WE STAY MOSTLY DRY TONIGHT. TEMPERATURES, UNDER INCREASINGLY
CLOUDY SKIES, WILL BE SEVERAL DEGREES WARMER THAN THE PAST FEW
MORNINGS...BLEND OF THE MET/MAV LOOKS GOOD.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
WHILE OPPRESSIVE HEAT WILL BUILD ACROSS THE SOUTHERN CONUS IN
ASSOCIATION WITH A STRENGTHENING ANTICYCLONE THIS WEEK, IT IS NOT
EXPECTED TO REACH OUR AREA THROUGH THE NEXT 7 DAYS AS THE REGION
WILL GENERALLY BE UNDER THE PRESENCE OF MEAN TROUGHING AND ONSHORE
FLOW AT THE SFC. TEMPS THRU THE PERIOD SHOULD BE NEAR TO SLIGHTLY
BELOW NORMAL FOR THIS TIME OF YEAR.
LOPRES IS EXPECTED TO MOVE OFF THE SOUTHEAST VA COAST TUESDAY
MORNING. MODELS CONTINUE THE TREND TOWARD A WEAKER, MORE PROGRESSIVE
SYSTEM, WHICH WILL RESULT IN A EARLIER END TO THE SHOWERS ACROSS THE
DELMARVA DURING THE MORNING. THERE MAY ALSO BE AN ISOLATED SHOWER
THAT DEVELOPS ACROSS THE HIGHER ELEVATIONS OF PA LATE IN THE DAY,
BUT THE BULK OF DIURNAL CONVECTION SHOULD BE CENTERED CLOSER TO THE
SHARPENING LLVL THETA-E RIDGE, WHICH WILL RESIDE WEST OF THE AREA.
OTHERWISE, DRY CONDITIONS PREVAIL. FCST MAX TEMPS RANGING FROM THE
MID 70S IN THE POCONOS TO MID 80S ALONG THE I-95 CORRIDOR ARE CLOSE
TO CLIMO.
A WEAK RIDGE OF HIPRES BECOMES ESTABLISHED ACROSS THE COASTAL MID
ATLANTIC TUESDAY NIGHT AND WEDNESDAY MORNING. ALTHOUGH MODEL
GUIDANCE HASN`T JUMPED ON IT YET, WILL HAVE TO WATCH FOR THE
POTENTIAL FOR FOG OR STRATUS DEVELOPMENT AS PERSISTENT ONSHORE FLOW
IN THE BOUNDARY LAYER DRAWS MARINE AIR INLAND.
THE NEXT SYSTEM TO IMPACT THE AREA WILL BE A WAVE OF LOPRES OVER THE
GREAT LAKES THAT MOVES SOUTHEASTWARD ALONG THE STALLED FRONTAL
BOUNDARY IN THE MID-ATLANTIC STATES WEDNESDAY AFTERNOON THROUGH
THURSDAY. THE DISTURBANCE IS ALSO FORECAST TO WEAKEN AS THE UPPER
LOW BECOMES AN OPEN WAVE BY THE TIME IT REACHES OUR AREA. THIS LOW
OF PAC NW ORIGIN IS NOT EXPECTED TO TAP INTO APPRECIABLE GULF OF
MEXICO MOISTURE DURING ITS CROSS-COUNTRY TREK. ACCORDINGLY, THE SETUP
DOES NOT PARTICULARLY SUPPORT A HEAVY RAINFALL EVENT OR A WASHOUT,
BUT THERE IS STILL A CHANCE FOR SHOWERS AND THUNDERSTORMS DURING THE
SECOND HALF OF THE WORK WEEK. CHANCE POPS INITIALLY CONFINED TO WEST
OF I-95 WEDNESDAY AFTERNOON, BEFORE THIS ACTIVITY WOULD TRY TO
ADVANCE EASTWARD INTO THE REST OF THE CWA WEDNESDAY NIGHT. POPS
THURSDAY HIGHEST CLOSER TO THE STATIONARY BOUNDARY OVER THE
DELMARVA/NORTHEAST MD/SOUTHEAST PA.
A RIDGE OF HIPRES OVER EASTERN CANADA IS EXPECTED TO NOSE DOWN INTO
THE FORECAST AREA FRIDAY THROUGH THE WEEKEND. MODELS NOW SHOW THE
HIGH BECOMING ESTABLISHED ALONG THE EASTERN SEABOARD SOONER THAN
PREVIOUS GUIDANCE HAD INDICATED. TRENDED TOWARD A DRIER FORECAST
FRIDAY INTO THE WEEKEND AS THE HIGH SHOULD ACT TO SHIFT THE OLD
FRONTAL BOUNDARY AND STORM TRACK SOUTH AND WEST OF THE AREA. ONSHORE
FLOW WOULD POSITION THE REGION IN COOLER, MORE STABLE AIRMASS
REGIME.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
TODAY...VFR. LIGHT AND VARIABLE WINDS THROUGH THE FIRST HALF OF THE
DAY BEFORE A SOUTHWEST FLOW ESTABLISHES ITSELF...LESS THAN 10 KNOTS.
SEA BREEZES POSSIBLE AT ACY AND MIV LATER THIS AFTERNOON.
TONIGHT...VFR. LIGHT AND VARIABLE WINDS. LOW-LEVEL MOISTURE BEGINS
TO CREEP BACK INTO THE REGION WITH A THICKENING STRATOCU DECK
POSSIBLE.
OUTLOOK...
TUESDAY...PRECIP EXITS SRN TERMINALS EARLY IN THE DAY AS LOW
PRESSURE MOVES OFF THE VA COAST. VFR CONDITIONS.
TUESDAY NIGHT THROUGH WEDNESDAY MORNING...STRATUS OR FOG POSSIBLE AS
ONSHORE FLOW DEVELOPS. BEST SETUP WOULD BE CLOSER TO THE COAST
(ACY/MIV).
WEDNESDAY AFTERNOON THROUGH THURSDAY NIGHT...CHANCE FOR SHRA/TSRA AS
A SERIES OF DISTURBANCES MOVE THRU THE REGION. LOCAL/TEMPORARY
FLIGHT RESTRICTIONS POSSIBLE.
FRIDAY...VFR CONDITIONS.
&&
.MARINE...
WE CONTINUE THE TRANQUIL SUB-SCA CONDITIONS TODAY AND TONIGHT. LIGHT
NORTHERLY WINDS WILL BACK TOWARDS THE SOUTH-SOUTHEAST DURING THE
COURSE OF THE DAY, AND REMAIN BELOW 10 KNOTS. SEAS WILL CONTINUE TO
RUN AROUND 2 TO 3 FEET. WINDS THEN VEER TOWARDS THE EAST LATE
TONIGHT AS A WEAK SURFACE LOW PRESSURE SLIDES EASTWARD TO OUR
SOUTH.
OUTLOOK...
TUESDAY...LOPRES MOVES OFF THE VA COAST. A TIGHT PRESSURE GRADIENT
TO THE NORTH OF THE LOW MAY PRODUCE EASTERLY WINDS 15-20 KT. SCA
POTENTIAL LOW.
WEDNESDAY THROUGH THURSDAY...ONSHORE FLOW CONTINUES BUT WILL WEAKEN
OVER TIME. TSRA POSSIBLE IN SOUTHERN WATERS ON THURSDAY.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KLEIN
NEAR TERM...GAINES/HEAVENER
SHORT TERM...HEAVENER
LONG TERM...KLEIN
AVIATION...HEAVENER/KLEIN
MARINE...HEAVENER/KLEIN
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
913 AM EDT MON AUG 18 2014
.SYNOPSIS...
A FRONTAL BOUNDARY WILL STALL OVER VIRGINIA TODAY. A WAVE OF LOW
PRESSURE WILL TRACK EASTWARD ALONG THE STALLED BOUNDARY TONIGHT
BEFORE MOVING OFFSHORE TUESDAY. THE FRONTAL BOUNDARY SHOULD REMAIN
NEARLY STATIONARY FROM THE GREAT LAKES TO THE SOUTHERN MID-ATLANTIC
STATES WEDNESDAY AND THURSDAY WHILE A SERIES OF DISTURBANCES RIDE
ALONG IT. THE FRONT WILL GRADUALLY SHIFT FARTHER SOUTH AND WEST OF
THE AREA FRIDAY AND THIS WEEKEND AS HIGH PRESSURE WEDGES DOWN FROM
EASTERN CANADA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATEST WATER VAPOR AND 11-3.9 IR SHOW THE QUASI-STATIONARY FRONTAL
BOUNDARY TO OUR SOUTH EXTENDING NORTHEAST INTO THE MARYLAND/WEST
VIRGINIA PANHANDLE. DRY AIR WILL CONTINUE TO PRESS INTO THE REGION
FROM THE NORTH THROUGH THE MORNING HOURS UNDER A LIGHT NORTHERLY
FLOW. WINDS ARE EXPECTED TO VEER TOWARDS THE WEST-SOUTHWEST LATER
THIS AFTERNOON AS THE FRONT WAVERS TO OUR SOUTH. A WEAK SURFACE LOW,
CURRENTLY ACROSS THE MID-WEST, WILL RIDE ALONG THIS FRONTAL BOUNDARY
LATER THIS AFTERNOON..STAYING TO THE SOUTH OF OUR CWA. RAIN WILL
BEGIN TO OVERSPREAD THE EXTREME SOUTHERN DELMARVA ZONES BY LATE THIS
AFTERNOON AND THEY DON`T LOOK TO GET NORTH OF DOVER TODAY. BASED
ON THE LATEST RAP AND HRRR WITH THE 9:30 AM UPDATE, PUSHED BACK
ANY RAIN CHANCE TILL AFTER 20Z. GREATER INSTABILITY AND LOW- LEVEL
MOISTURE CONVERGENCE, AS PWATS SWELL TOWARDS 1.75 INCHES, COULD
ALLOW FOR SCATTERED THUNDERSTORMS AND MODERATE RAINFALL.
ELSEWHERE, THE LOWER PWAT AIR IN PLACE WILL TAKE A WHILE TO MODIFY
SO WE EXPECT A DRY DAY WITH SOME INCREASING CLOUD COVER LATE IN THE
DAY. TEMPERATURES WILL RUN CLOSE TO NORMAL TODAY, LIKE THE PAST FEW
DAYS. DID RAISE TEMPERATURES SLIGHTLY ACROSS THE NORTH WITH THE
9:30 AM UPDATE AS WELL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
THE SURFACE WAVE ALONG THE FRONTAL BOUNDARY WILL PASS TO OUR SOUTH
LATE TONIGHT. THIS SYSTEM OVER THE PAST SEVERAL DAYS HAS TRENDED
TOWARDS A MORE SUPPRESSED, FASTER WEST-EAST MOVEMENT, AND A
SOUTHEASTERN TRACK THAT WOULD ALLOW FOR LESS SIGNIFICANT RAINFALL
THREAT THEN PREVIOUSLY THOUGHT...WE REMOVED THE MENTION FROM THE HWO
AT THIS TIME.
SURFACE FLOW BEGINS TO VEER TOWARDS THE EAST-SOUTHEAST BY THIS
EVENING BRINGING MORE LOW-LEVEL INTO THE REGION...EVERYWHERE. NOT
EXPECTING MUCH IN THE WAY OF RAIN CHANCES LATE TONIGHT, OUTSIDE OF
THE DELMARVA, WITHOUT MUCH SYNOPTIC SCALE LIFT AND DON`T THINK THE
SURFACE FLOW IS STRONG ENOUGH FOR UPGLIDE ACROSS OUR WESTERN ZONES,
SO WE STAY MOSTLY DRY TONIGHT. TEMPERATURES, UNDER INCREASINGLY
CLOUDY SKIES, WILL BE SEVERAL DEGREES WARMER THAN THE PAST FEW
MORNINGS...BLEND OF THE MET/MAV LOOKS GOOD.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
WHILE OPPRESSIVE HEAT WILL BUILD ACROSS THE SOUTHERN CONUS IN
ASSOCIATION WITH A STRENGTHENING ANTICYCLONE THIS WEEK, IT IS NOT
EXPECTED TO REACH OUR AREA THROUGH THE NEXT 7 DAYS AS THE REGION
WILL GENERALLY BE UNDER THE PRESENCE OF MEAN TROUGHING AND ONSHORE
FLOW AT THE SFC. TEMPS THRU THE PERIOD SHOULD BE NEAR TO SLIGHTLY
BELOW NORMAL FOR THIS TIME OF YEAR.
LOPRES IS EXPECTED TO MOVE OFF THE SOUTHEAST VA COAST TUESDAY
MORNING. MODELS CONTINUE THE TREND TOWARD A WEAKER, MORE PROGRESSIVE
SYSTEM, WHICH WILL RESULT IN A EARLIER END TO THE SHOWERS ACROSS THE
DELMARVA DURING THE MORNING. THERE MAY ALSO BE AN ISOLATED SHOWER
THAT DEVELOPS ACROSS THE HIGHER ELEVATIONS OF PA LATE IN THE DAY,
BUT THE BULK OF DIURNAL CONVECTION SHOULD BE CENTERED CLOSER TO THE
SHARPENING LLVL THETA-E RIDGE, WHICH WILL RESIDE WEST OF THE AREA.
OTHERWISE, DRY CONDITIONS PREVAIL. FCST MAX TEMPS RANGING FROM THE
MID 70S IN THE POCONOS TO MID 80S ALONG THE I-95 CORRIDOR ARE CLOSE
TO CLIMO.
A WEAK RIDGE OF HIPRES BECOMES ESTABLISHED ACROSS THE COASTAL MID
ATLANTIC TUESDAY NIGHT AND WEDNESDAY MORNING. ALTHOUGH MODEL
GUIDANCE HASN`T JUMPED ON IT YET, WILL HAVE TO WATCH FOR THE
POTENTIAL FOR FOG OR STRATUS DEVELOPMENT AS PERSISTENT ONSHORE FLOW
IN THE BOUNDARY LAYER DRAWS MARINE AIR INLAND.
THE NEXT SYSTEM TO IMPACT THE AREA WILL BE A WAVE OF LOPRES OVER THE
GREAT LAKES THAT MOVES SOUTHEASTWARD ALONG THE STALLED FRONTAL
BOUNDARY IN THE MID-ATLANTIC STATES WEDNESDAY AFTERNOON THROUGH
THURSDAY. THE DISTURBANCE IS ALSO FORECAST TO WEAKEN AS THE UPPER
LOW BECOMES AN OPEN WAVE BY THE TIME IT REACHES OUR AREA. THIS LOW
OF PAC NW ORIGIN IS NOT EXPECTED TO TAP INTO APPRECIABLE GULF OF
MEXICO MOISTURE DURING ITS CROSS-COUNTRY TREK. ACCORDINGLY, THE SETUP
DOES NOT PARTICULARLY SUPPORT A HEAVY RAINFALL EVENT OR A WASHOUT,
BUT THERE IS STILL A CHANCE FOR SHOWERS AND THUNDERSTORMS DURING THE
SECOND HALF OF THE WORK WEEK. CHANCE POPS INITIALLY CONFINED TO WEST
OF I-95 WEDNESDAY AFTERNOON, BEFORE THIS ACTIVITY WOULD TRY TO
ADVANCE EASTWARD INTO THE REST OF THE CWA WEDNESDAY NIGHT. POPS
THURSDAY HIGHEST CLOSER TO THE STATIONARY BOUNDARY OVER THE
DELMARVA/NORTHEAST MD/SOUTHEAST PA.
A RIDGE OF HIPRES OVER EASTERN CANADA IS EXPECTED TO NOSE DOWN INTO
THE FORECAST AREA FRIDAY THROUGH THE WEEKEND. MODELS NOW SHOW THE
HIGH BECOMING ESTABLISHED ALONG THE EASTERN SEABOARD SOONER THAN
PREVIOUS GUIDANCE HAD INDICATED. TRENDED TOWARD A DRIER FORECAST
FRIDAY INTO THE WEEKEND AS THE HIGH SHOULD ACT TO SHIFT THE OLD
FRONTAL BOUNDARY AND STORM TRACK SOUTH AND WEST OF THE AREA. ONSHORE
FLOW WOULD POSITION THE REGION IN COOLER, MORE STABLE AIRMASS
REGIME.
&&
.AVIATION /13Z MONDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
TODAY...VFR. LIGHT AND VARIABLE WINDS THROUGH THE FIRST HALF OF THE
DAY BEFORE A SOUTHWEST FLOW ESTABLISHES ITSELF...LESS THAN 10 KNOTS.
SEA BREEZES POSSIBLE AT ACY AND MIV LATER THIS AFTERNOON.
TONIGHT...VFR. LIGHT AND VARIABLE WINDS. LOW-LEVEL MOISTURE BEGINS
TO CREEP BACK INTO THE REGION WITH A THICKENING STRATOCU DECK
POSSIBLE.
OUTLOOK...
TUESDAY...PRECIP EXITS SRN TERMINALS EARLY IN THE DAY AS LOW
PRESSURE MOVES OFF THE VA COAST. VFR CONDITIONS.
TUESDAY NIGHT THROUGH WEDNESDAY MORNING...STRATUS OR FOG POSSIBLE AS
ONSHORE FLOW DEVELOPS. BEST SETUP WOULD BE CLOSER TO THE COAST
(ACY/MIV).
WEDNESDAY AFTERNOON THROUGH THURSDAY NIGHT...CHANCE FOR SHRA/TSRA AS
A SERIES OF DISTURBANCES MOVE THRU THE REGION. LOCAL/TEMPORARY
FLIGHT RESTRICTIONS POSSIBLE.
FRIDAY...VFR CONDITIONS.
&&
.MARINE...
WE CONTINUE THE TRANQUIL SUB-SCA CONDITIONS TODAY AND TONIGHT. LIGHT
NORTHERLY WINDS WILL BACK TOWARDS THE SOUTH-SOUTHEAST DURING THE
COURSE OF THE DAY, AND REMAIN BELOW 10 KNOTS. SEAS WILL CONTINUE TO
RUN AROUND 2 TO 3 FEET. WINDS THEN VEER TOWARDS THE EAST LATE
TONIGHT AS A WEAK SURFACE LOW PRESSURE SLIDES EASTWARD TO OUR
SOUTH.
OUTLOOK...
TUESDAY...LOPRES MOVES OFF THE VA COAST. A TIGHT PRESSURE GRADIENT
TO THE NORTH OF THE LOW MAY PRODUCE EASTERLY WINDS 15-20 KT. SCA
POTENTIAL LOW.
WEDNESDAY THROUGH THURSDAY...ONSHORE FLOW CONTINUES BUT WILL WEAKEN
OVER TIME. TSRA POSSIBLE IN SOUTHERN WATERS ON THURSDAY.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KLEIN
NEAR TERM...GAINES/HEAVENER
SHORT TERM...HEAVENER
LONG TERM...KLEIN
AVIATION...HEAVENER/KLEIN
MARINE...HEAVENER/KLEIN
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
720 PM EDT TUE AUG 19 2014
.UPDATE (TONIGHT AND WEDNESDAY)...
23Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A TYPICAL CONFIGURATION OF
THE MAIN NORTHERN STREAM FLOW LOCATED WELL TO OUR NORTH ACROSS THE
NORTHERN TIER OF THE COUNTRY AND SOUTHERN CANADA. SEEING A BIT OF A
DIP IN THE NORTHERN STREAM FLOW ASSOCIATED WITH A WEAK CUT-OFF LOW
ARRIVING OVER THE CALIFORNIA COAST THIS EVENING. OTHERWISE...THE
ONLY OTHER SIGNIFICANT ENERGY IS A SHORTWAVE DIGGING THROUGH THE
GREAT LAKES REGION WITH AN ASSOCIATED ROUND OF STRONG
THUNDERSTORMS.
CLOSER TO HOME WE FIND AN EAST-WEST ORIENTED UPPER RIDGE IN PLACE
OVER THE FLORIDA PENINSULA. THIS RIDGE HAS KEPT OUR WEATHER RATHER
QUIET...WITH JUST ENOUGH SUPPRESSION / WARM AIR ALOFT / AND WEAK
LAPSE RATES TO KEEP OUR AFTERNOON/EVENING STORM COVERAGE TO A NEAR
MINIMUM FOR THIS TIME OF YEAR. A FEW ISOLATED STORMS HAVE BEEN ABLE
TO BRIEFLY BUILD THROUGH THIS GENERALLY HOSTILE ENVIRONMENT TOWARD
DEEP CONVECTION...HOWEVER SO FAR NONE HAVE LASTED VERY LONG WITH A
SHORT LIFE CYCLE (EVEN FOR PULSE STORMS). AT THIS POINT...THE ONLY
ISOLATED CELLS WE HAVE ARE TO THE SOUTH OF THE I-4 CORRIDOR AND EAST
OF THE I-75 CORRIDOR. DO NOT EXPECT THIS TO CHANGE OVER THE NEXT
COUPLE OF HOURS UNTIL EVEN THESE CELLS WEAKEN AND DISSIPATE WITH THE
LOSS OF TERRESTRIAL DIURNAL HEATING.
STORMS ARE MORE ACTIVE THIS EVENING TO OUR NORTH OVER SOUTHERN
GEORGIA AND SOUTHERN ALABAMA...WHERE A WEAK SURFACE FRONT /TROUGH/
CONVERGENCE ZONE ARE PROVIDING THE ADDED FOCUS FOR UPDRAFTS AND
MULTICELL COMPLEXES. THIS BOUNDARY / REGION OF FOCUS MAY DRIFT A BIT
FURTHER SOUTH INTO THE DAY ON WEDNESDAY PER MANY NWP
MEMBERS...HOWEVER STILL DO NOT ANTICIPATE ANY ENHANCED STORM ACTION
REACHING OUR ZONES...BUT MORE LIKELY TO BE ALONG THE I-10 CORRIDOR.
AFTER AN UNEVENTFUL OVERNIGHT THAT SHOULD BE GENERALLY RAIN FREE
AFTER ANY EVENING STORMS ARE GONE...WEDNESDAY LOOKS TO BE ANOTHER
DAY WITH BELOW NORMAL STORM COVERAGE THROUGH THE AFTERNOON AND
EVENING. WEDNESDAY DOES LOOK TO BE A RATHER HOT DAY THOUGH. THE
COMBINATION OF WARM TEMPERATURES AND ENHANCED DEWPOINTS ALONG AND
WEST OF THE I-75 CORRIDOR ARE FORECAST TO RESULT IN HEAT INDICES
APPROACHING 105 IN SPOTS DURING THE AFTERNOON. THESE VALUES ARE
JUST A BIT SHY OF HEAT ADVISORY CRITERIA...BUT SHOULD STILL BE
RESPECTED BY THOSE WORKING OR PLAYING OUTDOORS FOR EXTENDED PERIODS
OF TIME.
&&
.AVIATION...
VFR CONDITIONS WILL GENERALLY PREVAIL THROUGH THE TAF PERIOD. AN
ISOLATED STORM NEAR KFMY/KRSW SHOULD FADE QUICKLY BY 01Z AND LEAVE
THE AREA MOSTLY RAIN-FREE FOR THE REMAINDER OF THE EVENING.
CONDITIONS SUGGEST ANOTHER DAY WITH BELOW NORMAL STORM COVERAGE FOR
WEDNESDAY. BEST CHANCE OF AN ISOLATED AFTERNOON STORM WILL BE FOR
KPGD...KFMY/KRSW. WILL ADD VCTS AFTER 16Z FOR THESE THREE
SITES...ALTHOUGH THE CHANCES OF ANYTHING BUT BRIEF RESTRICTIONS
APPEARS QUITE LOW.
&&
.MARINE...
HIGH PRESSURE ACROSS THE EASTERN GULF WILL KEEP WINDS AND SEAS BELOW
HEADLINE CRITERIA THROUGH THE FORECAST PERIOD. RAIN CHANCES WILL
REMAIN LOW THROUGH WEDNESDAY BEFORE INCREASED MOISTURE RETURNS TO
THE AREA ALLOWING FOR SLIGHTLY HIGHER RAIN CHANCES.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 79 93 79 94 / 10 10 10 30
FMY 77 94 77 95 / 10 30 20 40
GIF 76 95 76 96 / 10 20 10 30
SRQ 76 92 77 92 / 10 10 10 30
BKV 71 95 73 95 / 10 10 10 30
SPG 80 93 78 93 / 10 10 10 20
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE/AVIATION/MARINE...MROCZKA
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
936 AM EDT MON AUG 18 2014
.DISCUSSION...
TODAY...A BIT OF THE TASTE OF THE LAZY...HAZY DAYS OF SUMMER. EARLY
MORNING ENHANCED VISIBLE SATELLITE IMAGERY SHOWED THE NORTHERN EDGE
OF AN ELEVATED HAZE LAYER (SAHARAN AIR) WAS LIKELY AFFECTING OUR FAR
SOUTHERN SECTIONS AROUND LAKE OKEECHOBEE.
SUBTROPICAL RIDGE AXIS CONTINUES OVER THE SOUTHERN PENINSULA.
HENCE...CENTRAL FLORIDA SOUNDINGS CONTINUED TO SHOW THE ANOMALOUS
DEEP LAYER WESTERLY FLOW WE HAVE HAD FOR MUCH OF THE WET SEASON.
PRECIPITABLE WATER IS AROUND 1.7 INCHES BUT 700 MB TEMPS 9-10 DEGREES
CELSIUS AND SOME DRIER AIR JUST ABOVE THE SURFACE WILL LIMIT STORM
CHANCES ALONG THE SEA BREEZE BOUNDARIES. THE HIGHEST CHANCE FOR
STORMS WILL BE WITH THE EAST/WEST COLLISION LATE IN THE DAY. THE
LOCAL WRF AND HRRR SHOW THE SOUTHERN SEA BREEZE GETTING ACTIVE ABOUT
2-3 PM BUT THIS IS QUESTIONABLE DUE TO THE PARAMETERS NOTED ABOVE.
THEREFORE WILL CONFINE CHANCE POPS TO THE INLAND SOUTH.
WITH THE REDUCED COVERAGE OF SHOWERS/STORMS...IT WILL FEEL HOTTER...
LONGER. HEAT INDICES IN THE LOWER ONE HUNDREDS ARE NOT THAT MUCH
OUT OF THE NORM FOR AUGUST. VALUES MAY CREEP UP TO AROUND 105 IN A
FEW INTERIOR LOCATIONS...BUT THIS IS STILL BELOW HEAT ADVISORY
CRITERIA. THE MAIN THING THOUGH IS THAT THERE WILL BE LIMITED RAIN
COOLING.
&&
.AVIATION...
MAINLY VFR. THE CHANCE FOR STORMS IS TOO LOW TO INCLUDE IN THE
TAFS. THE HIGHEST CHANCE FOR STORMS SHOULD BE AT COASTAL TERMINALS
BUT EXPECT THIS WILL BE LATE IN THE DAY AS THE EAST/WEST SEA BREEZE
BOUNDARIES INTERACT.
&&
.MARINE...
TODAY...CONTINUED GOOD BOATING CONDITIONS WITH OFFSHORE FLOW 10
KNOTS OR LESS. SHOULD GET A SEA BREEZE PUSHING TO INTERIOR SECTIONS
OF THE COASTAL COUNTIES...SOUTH OF CANAVERAL. THE CHANCE FOR
OFFSHORE MOVING STORMS IS LOW AND WILL BE LATE IN THE DAY.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
FORECASTS...LASCODY
IMPACT WX...MOSES
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
320 PM EDT MON AUG 18 2014
.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
STALLED FRONTAL BOUNDARY STRETCHES FROM THE TN VALLEY TO THE
SOUTHERN MID ATLANTIC STATES. A HIGH PRESSURE RIDGE IS SITUATED
ACROSS NORTHERN FL. 500MB ANALYSIS AND WV LOOP SHOWS A POTENT
SHORTWAVE MOVING EAST ACROSS NORTHERN MS. THIS FEATURE WILL BE THE
FOCUS FOR LATE AFTERNOON AND EVENING CONVECTION ACROSS THE CWFA.
THE 16Z HRRR HAS THE BEST HANDLE ON THE ONGOING CONVECTION THIS
AFTERNOON. HAVE TRIED TO ORIENT THE POPS ACCORDING TO CURRENT RADAR
TRENDS AND CLOSE TO THE HRRR SOLUTION. GOOD INSTABILITY DOES EXIST
AT THE SURFACE...BUT LAPSE RATES REMAIN POOR UNTIL THE COLD POOL
ALOFT MOVES OVERHEAD. BY THE TIME THE SHORTWAVE NEARS THE
CWFA...INSTABILITY HAS DECREASED WITH THE LOSS OF HEATING.
HOWEVER...WITH UNIDIRECTIONAL FLOW...STORMS MAY MOVE REPEATEDLY OVER
THE SAME AREAS...WITH LOCALLY HEAVY RAINFALL POSSIBLE. AREAS TO THE
NORTH RECEIVED ONE TO TWO INCHES OF RAINFALL OVERNIGHT/EARLY THIS
MORNING...SO ANY TRAINING STORMS OR HEAVY RAINFALL MAY CAUSE SOME
LOCALIZED FLOODING.
BY EARLY TUESDAY...THE POTENT EVENING/OVERNIGHT SHORTWAVE WILL HAVE
MOVED OFF TO THE EAST. MODELS ARE PROGGING ANOTHER...WEAKER...
SHORTWAVE TO MOVE EAST IN THE FLOW TOMORROW. CONFIDENCE IS LOW ON
EXACTLY WHERE CONVECTION WILL DEVELOP TOMORROW.
NLISTEMAA
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
LONG TERM FORECAST IS ON TRACK AND HAVE NOT MADE SIGNIFICANT
ADJUSTMENTS. ONE ADDITIONAL POINT TO NOTE IS THAT HEAT INDEX VALUES
ARE CREEPING ABOVE 100 DEGREES SOUTH OF AN ATLANTA TO ATHENS
LINE...WITH PORTIONS OF CENTRAL GEORGIA APPROACHING 105 DEGREES
DURING THE SECOND HALF OF THE WEEK. IF THIS TREND CONTINUES...MAY
NEED A HEAT ADVISORY FOR THESE 105-108 DEGREE VALUES ACROSS THE
SOUTHEAST PART OF THE CWA.
11/ATWELL
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
00Z GFS AND ECMWF ARE IN UNCOMMONLY GOOD AGREEMENT THROUGH THE
EXTENDED FORECAST PERIOD AND CONTINUE THE RECENT TREND OF BUILDING
UPPER-LEVEL HIGH PRESSURE INTO THE CENTRAL GULF COAST REGION AND
LOWER MISSISSIPPI VALLEY FROM MID-WEEK THROUGH NEXT WEEKEND. BY THE
WEEKEND THE UPPER RIDGE IS QUITE STRONG...BUT GEORGIA REMAINS ON THE
EASTERN PERIPHERY. THIS SHOULD ALLOW VERY WARM TEMPERATURES AND
INHIBIT DIURNAL CONVECTION SOMEWHAT...BUT I DO NOT BELIEVE THE
FORECAST AREA IS CLOSE ENOUGH TO THE CENTER OF THE RIDGE TO
ELIMINATE POPS ALTOGETHER.
20
&&
.PREV DISCUSSION... /ISSUED 127 PM EDT MON AUG 18 2014/
AVIATION...
18Z UPDATE...
SCATTERED CONVECTION HAS DEVELOPED IN AREAS THAT HAVE RECEIVED
THE BETTER HEATING THIS MORNING. NO REAL FOCUSING MECHANISM AT THE
SURFACE OR ALOFT. POTENT SHORTWAVE ACROSS NORTHERN MS WILL MOVE
EAST ACROSS AL THIS AFTERNOON. MORE ORGANIZED PRECIP IS POSSIBLE
WITH THIS FEATURE...BUT THE HI-RES MODELS DON`T HAVE A GREAT
HANDLE ON THE SITUATION. WILL LEAVE OUT ANY TEMPO/PROB GROUPS AT
THIS TIME. MODELS ALSO HAVE SOME LOW CLOUDS DEVELOPING...BUT IT
MAY BE LATER DUE TO ANY PRECIP.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM CONFIDENCE ALL ELEMENTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 73 91 72 97 / 50 40 30 10
ATLANTA 74 88 73 94 / 40 40 30 10
BLAIRSVILLE 67 84 67 90 / 50 40 30 20
CARTERSVILLE 72 89 71 94 / 50 40 30 10
COLUMBUS 75 92 73 96 / 60 40 30 10
GAINESVILLE 72 89 71 94 / 50 40 30 10
MACON 75 92 72 97 / 50 40 30 10
ROME 72 89 71 95 / 60 40 30 20
PEACHTREE CITY 73 89 71 94 / 50 40 30 10
VIDALIA 77 95 74 97 / 50 40 30 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...
LONG TERM....ATWELL
AVIATION...NLISTEMAA
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
420 AM EDT MON AUG 18 2014
.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL REMAIN SOUTHEAST OF THE REGION THROUGH FRIDAY
WITH A TROUGH OF LOW PRESSURE INLAND. A COLD FRONT WILL DROP THROUGH
THE AREA OVER THE WEEKEND WITH HIGH PRESSURE BUILDING IN FROM THE NORTH
INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
PRE-DAWN...DEEP LAYERED MOISTURE HAS BEEN INCREASING OVER OUR FORECAST
AREA THIS MORNING AS EVIDENCED BY WATER VAPOR SATELLITE IMAGERY AND
ANALYSIS OF HOURLY PWATS FROM THE OPERATIONAL EMC RAP MODEL ONLINE.
DESPITE THE CHANGE IN MOISTURE PROFILES...MODELS SHOW A GOOD BIT
OF CONVECTIVE INHIBITION AT DAYBREAK. WE CANNOT TOTALLY RULE OUT
ISOLATED SHOWERS DEVELOPING ON THE BEACHES OR BARRIER ISLANDS BUT
IT SHOULD SLIP OFFSHORE. NO FOG ISSUES THIS MORNING...TEMPS ARE
WARM IN THE MID TO UPPER 70S WITH A DECENT PRES GRADIENT IN THE
BOUNDARY LAYER.
THE SUBSIDENCE WE HAD AROUND ON SUNDAY HAS DEPARTED OUR REGION THIS
MORNING AND MID LEVEL HEIGHTS ON THE NW PERIPHERY OF THE SUBTROPICAL
RIDGE OVER THE SW ATLC HAVE FLATTENED AND SLIGHTLY WEAKENED. A
SHORT WAVE AND ASSOCIATED MID LEVEL VORT MAX IS FORECAST TO PASS
BY TO THE NORTH TODAY WITH A WEAKER BIT OF VORTICITY ADVECTION
RIPPLING ACROSS S GEORGIA THIS MORNING. WEST FLOW IN THE LOW
LEVELS SHOULD ENSURE ANOTHER HOT DAY IN THE 90S BUT EVENTUAL
CONVECTIVE INITIATION AND DEEPER MOISTURE PROFILES/CLOUD POTENTIAL
COULD KEEP AREAS FROM MAXIMIZING READINGS WARMER THAN THE MID 90S
THIS AFTERNOON. HEAT INDEX VALUES WILL LIKELY TOP OUT IN THE 103
TO 105 DEGREE RANGE THIS AFTERNOON AS CONDITIONS WILL BE MORE HUMID
TODAY WITH ELEVATED SURFACE DEW POINTS.
CONSENSUS OF THE MODELS SUGGEST ISOLATED CONVECTION PERHAPS BREAKING
OUT PRIOR TO MID AFTERNOON ACROSS AREAS WEST OF I-95 AS HINTED BY
ADVECTION OF HIGHER 850 MB THETA-E VALUES FROM SW AND CENTRAL
GEORGIA BY 18Z. SHOWER AND TSTM CONVERAGE OVER SE GEORGIA COULD BE
SCATTERED IN SOME LOCATIONS BY MID AFTERNOON BUT POPS NO HIGHER
THAN 25-30 PERCENT IN THAT AREA.
THE MOST IMPRESSIVE LOCATIONS FOR STRONGER CONVECTION LATER TODAY
AND EARLY THIS EVENING WILL EXTEND ACROSS THE NORTH CAROLINA
SANDHILLS SOUTH TO THE EASTERN SOUTH CAROLINA MIDLANDS AND PEE DEE
REGIONS. GRADUALLY INCREASING DEEP LAYERED WIND FIELDS AND RICH
LOW LEVEL MOISTURE CONVERGENCE FUELED BY A WELL DEFINED SURFACE
TROUGH NOTED IN THIS AREA. STEERING PROGS FOR EAST CENTRAL SOUTH
CAROLINA SHOW ENOUGH OF A VEER FROM THE W TO WNW TO SUGGEST SOME
SIGNIFICANT MULTI-CELL OR LINEAR CONVECTION HAVING A CHANCE TO MAKE
A RUN FOR OUR NW TIER AND THE CHARLESTON TRI-COUNTY LATE IN THE
DAY. IF IT DOES...THERE WOULD BE A POTENTIAL WINDOW FOR ISOLATED
SEVERE WEATHER FROM MAINLY DAMAGING WIND GUSTS. THERE IS A BIT TOO
MUCH TIMING AND SPACIAL DIFFERENCES FROM THE HIGHER RESOLUTION
MODELS AT 00Z TO HOLD OUT SEVERE WEATHER MENTIONS IN OUR
HAZARDOUS WEATHER OUTLOOK...BUT IT MAY NEED TO BE INCLUDED ON THE
MORNING UPDATE AFTER 12Z DATA IS ANALYZED. WE BUMPED POPS TO 40
PERCENT ACROSS AREAS NORTH OF CHARLESTON TO TREND.
CONVECTION SHOULD DIMINISH OR MOVE OFFSHORE OF SOUTH CAROLINA COAST
AFTER MID EVENING WITH PARTLY CLOUDY SKIES ALL AREAS OVERNIGHT
ALONG WITH A LIGHT SW BREEZE. POPS SILENT AFTER MIDNIGHT WITH LOWS
73-77 DEGREES.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
TUESDAY...A POTENT SHORTWAVE WILL PASS THROUGH SC DURING THE EARLY
TO MID AFTERNOON. A JUICY AIRMASS WILL BE IN PLACE WITH PWATS ABOVE
2 INCHES. ALTHOUGH THE TIMING ON THE INCREASING SKY COVER AND PRECIP
COULD AFFECT HIGH TEMPS...STRONG WESTERLY FLOW IN ADVANCE OF THE
VORT MAX SUPPORT HIGH TEMPS REACHING THE MIDDLE 90S MOST AREAS.
CLUSTERS OF SHOWERS AND TSTMS EXPECTED TO DEVELOP UPSTREAM AND
EXPAND INTO THE AREA DURING THE AFTERNOON. ALTHOUGH THE
THERMODYNAMIC PROFILES ARE NOT GOING TO BE TOO TERRIBLY
IMPRESSIVE...GIVEN THE FORCING AND TIME OF YEAR WE CANNOT RULE OUT A
FEW SEVERE STORMS.
THE 500 MB RIDGE WILL GRADUALLY BUILD ACROSS THE AREA WEDNESDAY AND
THURSDAY WITH INCREASING UPPER HEIGHTS AND DEEP WNW FLOW. ASIDE FROM
SOME CIRRUS...SKIES SHOULD BE SUNNY BOTH DAYS WITH LATE AFTERNOON
SEA BREEZE CIRCULATIONS ALONG THE COAST. THICKNESSES SUPPORT HIGH
TEMPS IN THE UPPER 90S BOTH DAYS WITH TEMPS REACHING THE LOWER TO
MIDDLE 90S NEAR THE IMMEDIATE COAST. ON THURSDAY WE COULD EASILY SEE
SOME READINGS AT THE CENTURY MARK ACROSS INLAND GA. FAIRLY WARM MID
LEVELS AND LACK OF APPRECIABLE FORCING WILL ONLY SUPPORT ISOLATED
SHOWERS AND TSTMS BOTH DAYS. THE HEAT INDICES ARE THE MAIN CONCERN.
THE EXACT DEWPOINTS AT THE TIME OF MAX TEMP ARE CRITICAL TO
DETERMINING THE HEAT ADVISORY POTENTIAL. HOWEVER IT IS VERY
DIFFICULT TO PIN DOWN THE DEWPOINTS THIS FAR IN ADVANCE. OUR CURRENT
FORECAST SHOWS HEAT INDICES TOPPING OUT AT 106-109 ON WEDNESDAY AND
105-110 ON THURSDAY. WE CANNOT RULE OUT A HEAT ADVISORY FOR PORTIONS
OF THE AREA EITHER DAY...THOUGH THURSDAY IS LOOKING LIKE THE WORST
OF THE TWO DAYS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
THE UPPER RIDGE AXIS TO OUR WEST WILL BECOME MORE AMPLIFIED WHILE A
TROUGH CARVES OUT ACROSS THE MID-ATLANTIC REGION. MEDIUM RANGE
GUIDANCE IS IN GOOD AGREEMENT THAT A BACKDOOR COLD FRONT WILL DROP
TOWARD THE AREA ON FRIDAY...PUSHING THROUGH ON SATURDAY.
COMPRESSIONAL HEATING ON FRIDAY AHEAD OF THE FRONT WILL YIELD HIGHS
IN THE MID TO UPPER 90S. SOMEWHAT COOLER CANADIAN HIGH PRESSURE
BUILDS IN FROM THE NORTH SUNDAY INTO MONDAY WITH INCREASING RAIN
CHANCES AS BETTER CONVERGENCE DEVELOPS.
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
VFR CONDITIONS PREVAIL THROUGH 06Z TUESDAY. ISOLATED TO SCATTERED
CONVECTION IS POSSIBLE AFTER MID AFTERNOON AT BOTH TERMINALS BUT
AT THIS TIME...CONFIDENCE IN TIMING AND COVERAGE IS TOO LOW FOR
INTRODUCTIONS OF VCTS TO THE FORECAST. THE 12Z TAF WILL LIKELY
INTRO SOME VCTS AT KCHS...STILL EVALUATING AT THIS TIME.
EXTENDED AVIATION OUTLOOK...ISOLATED TO SCATTERED AFTERNOON
SHRA/TSRA EXPECTED THROUGH FRIDAY WITH VERY BRIEF FLIGHT
RESTRICTIONS POSSIBLE.
&&
.MARINE...
THE COASTAL WATERS ARE BETWEEN A LOW PRES AREA OVER THE SOUTHERN
MID ATLC REGION AND HIGH PRES LODGED IN TO THE SOUTH. AN ENHANCED
PRES GRADIENT WILL SUPPORT SW FLOW 10 TO 15 KT WITH LATE DAY
ENHANCEMENTS. NOCTURNAL SURGING TONIGHT WILL RESULT IN A MORE
SOLID 15 KT ACROSS NEAR SHORE WATERS WITHIN 10 MILES AND UP
TO 20 KT ONCE AGAIN BEYOND THE PILOT BUOYS...ESPECIALLY FROM
GRAYS REEF SEAWARD. SEAS 2 TO 3 FT ON AVERAGE NEAR SHORE TODAY
AND 3 TO 4 FT TONIGHT. A PERIOD OF 5 FT WAVES ARE POSSIBLE IN
OUTER GEORGIA WATERS.
ATLANTIC HIGH PRESSURE TO THE SOUTHEAST AND AN INLAND TROUGH WILL
MAINTAIN AN ENHANCED SW WIND FLOW TUESDAY AND TUESDAY NIGHT WITH
WIND SPEEDS UPWARDS OF 15-20 KT. A RELAXING GRADIENT WEDNESDAY
THROUGH SATURDAY WILL DROP WINDS TO 15 KT OR LESS. OVER THE WEEKEND
A FRONT WILL DROP THROUGH THE WATERS WITH WINDS SWINGING AROUND TO
NE.
&&
.EQUIPMENT...
THE CHARLESTON SC WSR-88D /KCLX/ REMAINS OUT OF SERVICE DUE TO A
SIGNIFICANT MECHANICAL FAILURE. REPAIR WORK CONTINUES AND THE
RADAR COULD BECOME OPERATIONAL AS EARLY AS AUGUST 20TH OR 21ST.
UNTIL THE CHARLESTON SC RADAR RETURNS TO SERVICE...FOR DOPPLER
RADAR COVERAGE OF SOUTHEAST GEORGIA AND SOUTH COASTAL SOUTH
CAROLINA UTILIZE SURROUNDING RADARS INCLUDING KJAX...KJGX...
KVAX...KCAE AND KLTX.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS POCATELLO ID
144 PM MDT MON AUG 18 2014
.DISCUSSION...CENTER OF UPPER LOW OVER NORTHERN CALIFORNIA PER WV
IMAGERY. MOISTURE PULLING NORTH THROUGH NEVADA AND NORTHERN
ARIZONA THROUGH GREAT BASIN TOWARD EASTERN IDAHO. PAIR OF WEAK
SHORTWAVES MOVING THROUGH EAST IDAHO...ONE ALONG DIVIDE AND
ANOTHER ALONG SOUTHERN BORDER. SOME MOISTURE IN PLACE ALREADY AND
CONVECTION HAS BEGUN TO REDEVELOP ALREADY EARLY THIS AFTERNOON
ALONG/AHEAD OF SHORTWAVES. NAM/RAP SEEMS TO HAVE BEST HANDLE ON
CONVECTIVE THREAT THIS AFTERNOON AND EVENING WHILE HRRR STRUGGLING
TO CATCH UP. BOTH NAM/GFS CONTINUE CONVECTION OVERNIGHT INTO EARLY
TUESDAY BUT CONVECTION BLOOMS DURING THE AFTERNOON AS MID LEVEL
MONSOON FLOW REACHES EAST IDAHO. HAVE NUDGED POPS UPWARD TUESDAY
ALL AREAS. SOME DIFFERENCES IN MODELS AS NAM STRONGER WITH
SHORTWAVE EJECTING OUT OF EAST IDAHO TUESDAY NIGHT. DIFFERENCES
AMPLIFY THROUGH THURSDAY WITH NAM A BIT FURTHER SOUTH WITH BASE OF
TROUGH. GFS HOLDS EAST IDAHO IN NEUTRAL FLOW ALOFT WITH SOUTHERN
CUT OFF LOW FURTHER NORTH THAN THE NAM. BOTH MODELS REMAIN
UNSETTLED WITH PLENTY OF MOISTURE IN PLACE TO CONTINUE THREAT OF
SCATTERED THUNDERSTORMS ACROSS THE REGION. SHORTWAVE ROUNDS TROUGH
WEDNESDAY NIGHT INTO THURSDAY FOR ANOTHER WET DAY MOST AREAS WITH
EASTERN IDAHO JUST AHEAD OF MAIN TROUGH AXIS. BOTH MODELS
PRODUCING MORE WIDESPREAD CONVECTIVE CONVERAGE SO NUDGED POPS
UPWARD AGAIN FOR THURSDAY AFTERNOON/EVENING.
ECMWF AND GFS AGAIN DIFFEREING IN DETAILS FOR REMAINDER OF FORECAST.
ECMWF LOOKING AGAIN TO DROP CLOSED SHORTWAVE INTO BASE OF BROAD
PACNW TROUGH THURSDAY NIGHT INTO FRIDAY BUT THEN OPENS IT UP AGAIN
FRIDAY NIGHT. PLACEMENT/DEPTH OF TROUGH SIMILAR WITH HINTS OF DRY
SLOT WORKING IN FROM OREGON FRIDAY INTO SATURDAY. BOTH MODELS
TREAT NORTHERN PACIFIC ENERGY A LITTLE DIFFERENTLY. EAST IDAHO
UNDER SOME INFLUENCE OF BASE OF TROUGH...BUT FLOW RANGES FROM
WEST/DRY IN THE GFS TO NORTHWEST/MOIST IN THE ECMWF. OVERALL OPTED
TO MAKE NO CHANGES TO CURRENT EXTENDED RANGE WITH ISOLATED POPS
CLOSE TO CLIMO AND TEMPS NEAR GUIDANCE BLEND. DMH
&&
.AVIATION...SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH TOMORROW
ACROSS EASTERN IDAHO. COVERAGE WILL BE ISOLATED TODAY BECOMING
CLOSER TO SCATTERED IN SOME AREAS ON TUESDAY. GUSTY WINDS OVER 30KTS
ARE POSSIBLE WITH STORMS...WITH AN INCREASING THREAT OF HEAVY
DOWNPOURS TONIGHT AND TUESDAY. EITHER COULD BRING REDUCED
VISIBILITY. WE WILL BE CARRYING AT LEAST VCTS OR VCSH FOR ALL SITES.
KEYES
&&
.FIRE WEATHER...SHOWERS AND STORMS WILL CONTINUE TO INCREASE ACROSS
EASTERN IDAHO THROUGH THE NEXT 24 HOURS. THUNDERSTORM COVERAGE WILL
BE ISOLATED TODAY AND WIDELY SCATTERED TOMORROW. THE SOUTHEAST
CORNER WILL BE INTERESTING TO WATCH AS THEY MAY BE TOO STABLE TO SEE
ANY THUNDER AT ALL IF CLOUDS AND TIMING MATCH UP. STORMS WILL BE
CAPABLE OF PRODUCING WIND GUSTS OVER 35 MPH AND LOCALLY HEAVY
DOWNPOURS. WE ARE NOT EXPECTING ANY ISSUES WITH SLIDES OR FLOODING
THIS TIME AROUND. ISOLATED TO WIDELY SCATTERED THUNDERSTORMS WILL
CONTINUE THROUGH THE END OF THE WEEK AS THE LOW OUT OF CANADA SAGS
SOUTH INTO THE NORTHERN STATES. THE BETTER CHANCES WEDNESDAY-FRIDAY
WILL BE ACROSS THE NORTH AND ALONG THE WYOMING BORDER. DRIER
CONDITIONS WILL FILTER INTO PORTIONS OF THE SNAKE PLAIN AND
SOUTH-CENTRAL HIGHLANDS...HELPING TO REDUCE SHOWERS/STORMS. WE WILL
ALSO SEE THE WIND PICKING UP...BUT INCREASED HUMIDITY SHOULD NEGATE
THIS AND PREVENT ANY ISSUES WITH CRITICAL FIRE CONDITIONS. THE
MODELS CONTINUE TO SHOW WIDELY VARYING FORECASTS EACH DAY IN THE
EXTENDED...BUT ONE TREND IS EMERGING DESPITE ALL OF THIS. IT DOES
APPEAR FOR THE WEEKEND AND EARLY NEXT WEEK...WE SHOULD BR PRETTY DRY
BUT BREEZY ACROSS THE SOUTH AND SNAKE PLAIN. WE SLOWLY TRENDED THAT
DIRECTION WITH THE FORECAST WHERE IT WAS NEEDED...BUT NOT COMPLETELY
TO THAT END OF THE SPECTRUM. KEYES
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
835 PM CDT TUE AUG 19 2014
.DISCUSSION...
835 PM CDT
FOR EVENING UPDATE...
HAD ADJUSTED POPS/WX AND SKY COVER EARLIER BASED ON RADAR/SATELLITE
TRENDS. OTHER THAN DETAILS OF ENDING/MOVING ISOLATED SHRA OUT OF
NORTHEAST IL/NORTHWEST IN NEXT COUPLE OF HOURS...NO SIGNIFICANT
CHANGES MADE TO GOING FORECAST.
A FEW ISOLATED SHOWERS CONTINUE TO BUBBLE IN A COUPLE OF SPOTS AT
0115Z...ONE NEAR KANKAKEE...AND THE OTHER ACROSS NORTHERN COOK
COUNTY NEAR OHARE AND JUST OFF THE LAKE SHORE BETWEEN KENILWORTH AND
EVANSTON. THESE SHOWERS WERE OCCURRING ALONG A WEAK SURFACE TROUGH
AXIS WHICH STRETCHED FROM SOUTHERN LAKE MICHIGAN TO NORTH OF ST
LOUIS...AND AHEAD OF A MID-LEVEL SHORT WAVE TROUGH ROTATING EASTWARD
ACROSS NORTHWEST IL/WISCONSIN PER GOES VAPOR IMAGERY. THESE SHOWERS
HAVE DIMINISHED CONSIDERABLY IN COVERAGE WITH SUNSET AND THE
WEAKENING OF DIURNALLY-DRIVEN INSTABILITY...AND LINGERING SHOWERS
ARE EXPECTED TO CONTINUE TO WEAKEN AND DISSIPATE OR MOVE OVER LAKE
MICHIGAN IN THE NEXT HOUR OR TWO. STRONGER STORMS WHICH HAD FORMED
OVER PARTS OF EAST CENTRAL IL AND NORTHWEST INDIANA LATE THIS
AFTERNOON ALSO OCCURRED AHEAD OF A MORE COMPACT VORT MAXIMA SEEN
PUSHING EAST ACROSS CENTRAL IL AT THIS TIME... AND WITHIN A MORE
UNSTABLE ENVIRONMENT ASSOCIATED WITH POOLED UPPER 60S AND LOWER 70S
SURFACE DEW POINTS AHEAD OF THE SURFACE TROUGH. THESE STRONGER
STORMS HAVE MOVED OFF TO THE EAST OF THE CWA INTO CENTRAL AND
NORTHERN INDIANA. GOES 11-3.9 MICRON IR IMAGERY INDICATES LITTLE
LEFT OF DIURNAL CU FIELD ACROSS SOUTHERN WI/NORTHERN IL WEST OF
CHICAGO...SUGGESTING DRY CONDITIONS FOR THE MAJORITY OF THE AREA FOR
THE REMAINDER OF THE EVENING/OVERNIGHT HOURS. ANOTHER MID-LEVEL VORT
ROTATING SOUTH-SOUTHEASTWARD ACROSS CENTRAL MN HAS SOME ISOLATED
CONVECTION NEAR THE MSP AREA...AND HIGH-RES GUIDANCE DOES INDICATE
THE POTENTIAL FOR A FEW ISOLATED SHOWERS TO DEVELOP INTO NORTHEAST
IA/NORTHWEST IL TOWARD MORNING. STILL...APPEARS FAIRLY LOW CHANCE
WITH BETTER PRECIP POTENTIAL BECOMING FOCUSED BACK ACROSS
NEBRASKA/WESTERN IA BY MORNING.
HAD ADJUSTED POPS/WX AND SKY COVER EARLIER BASED ON RADAR/SATELLITE
TRENDS. OTHER THAN DETAILS OF ENDING/MOVING ISOLATED SHRA OUT OF
NORTHEAST IL/NORTHWEST IN NEXT COUPLE OF HOURS...NO SIGNIFICANT
CHANGES MADE TO GOING FORECAST.
RATZER
&&
.PREV DISCUSSION...
304 PM CDT
WARMER AND MORE HUMID CONDITIONS ARE STILL EXPECTED AS WE GO THROUGH
THE REST OF THE WEEK WITH THE BIGGEST CHALLENGE BEING THE
DETERMINATION OF THE EXTENT OF SHOWER AND THUNDERSTORM ACTIVITY.
AFTERNOON WATER VAPOR IMAGERY SHOWS AN UPPER TROUGH OVERHEAD OF THE
LOCAL AREA MAKING GRADUAL PROGRESS TO THE EAST. BROAD LOW-AMPLITUDE
RIDGING IS IN PLACE OVER THE ROCKIES AND HIGH PLAINS WHILE A BROAD
UPPER TROUGH MOVES ACROSS WESTERN CANADA. A CUTOFF UPPER LOW IS
SPINNING SOUTHWARD DOWN THE CALIFORNIA COAST. THIS RIDGE/TROUGH
COMBINATION WILL AMPLIFY OVER THE NEXT FEW DAYS AND MAKE EASTWARD
PROGRESS. AT THE SURFACE...LOW PRESSURE IS OVER NORTHERN MICHIGAN IS
DRAGGING A COOL FRONTAL BOUNDARY/TROUGH SOUTHEAST ACROSS THE LOCAL
AREA.
TONIGHT AND WEDNESDAY...THE UPPER TROUGH OVER THE AREA TODAY WILL BE
SLOW TO MOVE EAST INTO WEDNESDAY KEEPING CYCLONIC FLOW OVERHEAD
THROUGH THE MORNING. THE BULK OF THE CONVECTIVE ACTIVITY IS NOW OFF
TO THE EAST WITH MORE SPOTTY DIURNALLY DRIVEN ACTIVITY WORKING INTO
THE NORTHERN CWA AND MAY SEE SOME ADDITIONAL ACTIVITY INTO CENTRAL
AREAS BEFORE DISSIPATING THIS EVENING. OTHERWISE...WATER VAPOR SHOWS
A WEAK WAVE ROUNDING THE PERIPHERY OF THE UPPER LOW OVER MINNESOTA
THIS AFTERNOON AND THIS SHOULD ROTATE OVER THE LOCAL AREA TONIGHT
AND MAY TRIGGER SOME ADDITIONAL SHOWERS. THE CHANCE DOES NOT LOOK
THAT GREAT ESPECIALLY WITH A MODESTLY DRIER AIRMASS IN PLACE BEHIND
THE AFTERNOON TROUGH. CYCLONIC FLOW REMAINS OVERHEAD WEDNESDAY
MORNING BUT SHIFTS TO THE EAST SO AM NOT EXPECTING PRECIP ACTIVITY
GIVEN THE POOR DIURNAL SUPPORT THEREFORE MUCH OF THE DAY WEDNESDAY
SHOULD BE DRY. HIGHS WILL WARM INTO THE LOW TO MID 80S BUT A LAKE
BREEZE SHOULD COOL LAKESHORE AREAS DURING THE AFTERNOON.
WEDNESDAY NIGHT THROUGH FRIDAY...THE UPPER RIDGE WILL MOVE FROM THE
HIGH PLAINS AND SLOW ITS EASTWARD PROGRESS OVER THE LOCAL AREA BY
FRIDAY. IT WILL AMPLIFY AS IT MOVES EASTWARD HELPING TO SHARPEN THE
ASSOCIATED MID LEVEL BAROCLINIC ZONE WHICH WILL MOVE NORTHEAST
ACROSS THE FORECAST AREA STARTING BY WEDNESDAY EVENING. WITH A
STRONG PUSH OF MOISTURE AND A WEST TO SOUTHWEST LOW LEVEL JET
DEVELOPING WEDNESDAY EVENING SHOULD SEE A DECENT COVERAGE OF SHOWERS
AND THUNDERSTORMS DEVELOP AND MOVE ACROSS THE AREA INTO THURSDAY
MORNING. BETTER ORGANIZATION COULD RESULT WITH THE PASSAGE OF ANY
SHORTWAVE EJECTING FROM THE AMPLIFYING BUT STILL BROAD WESTERN
TROUGH. LESS CONFIDENT IN PRECIP CHANCES FROM LATE THURSDAY THROUGH
FRIDAY AS THE RIDGE AXIS WILL BE OVER THE AREA BUT THE RIDGE LOOKS
TO BE BROAD ENOUGH THAT THE MORE ACTIVE FLOW AROUND THE PERIPHERY
WILL BE IN CLOSE PROXIMITY. ULTIMATELY A WARM FRONTAL BOUNDARY WILL
LIKELY SET UP TO THE NORTH EXTENDING FROM LOW PRESSURE ACROSS THE
CENTRAL/NORTHERN PLAINS BUT CONVECTION MAY INFLUENCE HOW FAR
NORTH-SOUTH THIS BOUNDARY MOVES WHICH WILL AFFECT POPS AND POSSIBLY
TEMPS AS WELL. WILL CONTINUE WITH THE IDEA OF THE BOUNDARY REMAINING
NORTH LEADING TO HIGHS IN THE MID AND UPPER 80S THURSDAY AND UPPER
80S TO AROUND 90 FRIDAY. THE FLOW MAY BE WEAK ENOUGH TO ALLOW SOME
LAKE INFLUENCE TO COOL SHORELINE AREAS SOMEWHAT. ANY OUTFLOW FROM
STORMS OVER OR NORTH OF THE AREA COULD IMPACT TEMPS AS WELL.
SATURDAY AND BEYOND...THE WESTERN TROUGH WILL EVENTUALLY TRACK EAST
ACROSS THE NORTHERN PLAINS BREAKING DOWN THE RIDGE BUT THE SPEED
WITH WHICH THIS OCCURS IS STILL IN QUESTION. AT THIS POINT THE RIDGE
LOOKS TO FURTHER AMPLIFY OVER THE WEEKEND WHICH COULD KEEP THINGS
DRY BUT GUIDANCE HAS FLUCTUATED ON THE AMPLITUDE. WILL KEEP LOW POPS
SATURDAY AND SUNDAY...MAINLY NORTH CLOSER TO THE MORE ACTIVE FLOW
AROUND THE TOP OF THE RIDGE. TEMPS IN THE UPPER 80S TO AROUND 90
WILL CONTINUE ALONG WITH THE HUMIDITY. AS THE UPPER TROUGH MOVES
EAST SURFACE LOW PRESSURE WILL LIKELY DEVELOP ACROSS THE NORTHERN
PLAINS AND DRAG A COLD FRONT INTO THE AREA EARLY NEXT WEEK. THE
OVERALL UPPER PATTERN WILL BE DE-AMPLIFYING SO THE FRONT MAY STALL
OUT SOMEWHERE NEAR THE AREA BUT STILL QUITE A WAYS OUT THERE FOR ANY
KIND OF CONFIDENCE IN THIS.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* ISOLATED SHRA/TSRA THRU EARLY EVENING.
* GUSTY WESTERLY WINDS THRU EARLY EVENING.
* POSSIBLE FOG/MVFR VIS OVERNIGHT/WEDNESDAY MORNING.
* POSSIBLE LAKE BREEZE LATE WEDNESDAY AFTERNOON/EARLY EVENING. CMS
//DISCUSSION...UPDATED 00Z...
ISOLATED SHOWERS HAVE DEVELOPED ALONG A WEAK BOUNDARY/WIND SHIFT
EXTENDING ACROSS NORTHERN COOK/NORTHERN KANE AND NORTHERN DE KALB
COUNTIES. ADDITIONAL ISOLATED CONVECTION CONTINUES SOUTH OF
C09/JOT AND OVER THE LAKE. THIS ACTIVITY WILL CONTINUE THROUGH
SUNSET BUT IS EXPECTED TO REMAIN ISOLATED WITH LIMITED LIGHTNING.
MORE WIDESPREAD CONVECTION SOUTH BETWEEN RZL AND LAF WILL CONTINUE
EAST AND REMAIN WELL SOUTH OF THE TERMINALS.
WESTERLY WINDS 10-12KTS WITH SOME HIGHER GUSTS WILL DIMINISH OVER
THE NEXT HOUR AND CONTINUE TO DIMINISH TO 5KTS OR LESS THIS
EVENING WITH WINDS BECOMING LIGHT AND VARIABLE IN SOME AREAS. WITH
MAINLY CLEAR SKIES...TEMPS COOLING TO THE DEWPOINTS WILL LIKELY
LEAD TO SOME FOG FORMATION...BUT CONFIDENCE REGARDING SPECIFIC
VISIBILITIES AND HOW WIDESPREAD FOG BECOMES IS LOW AND TRENDS WILL
NEED TO BE MONITORED THRU THE NIGHT.
WESTERLY WINDS INCREASE MID/LATE MORNING WEDNESDAY WITH FORECAST
SOUNDINGS SUGGESTING PREVAILING WINDS AROUND 10 KT. WINDS DO
APPEAR TO WEAKEN SLIGHTLY THRU THE MID/LATE AFTERNOON AND A LAKE
BREEZE IS EXPECTED TO DEVELOP NEAR THE LAKE AND EVENTUALLY MOVE
INLAND...BUT PROBABLY NOT REACHING ORD/MDW UNTIL LATE AFTERNOON OR
EARLY EVENING AND DURING THAT TIME...PREVAILING WINDS ALSO BEGIN
TO TURN SOUTHEASTERLY. CMS
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* LOW FOR ISOLATED SHRA/TSRA THRU EARLY EVENING.
* HIGH FOR WINDS THRU EARLY WEDNESDAY AFTERNOON.
* LOW FOR FOG/MVFR VIS POTENTIAL OVERNIGHT/WEDNESDAY MORNING.
* LOW FOR LAKE BREEZE AND TIMING. CMS
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
* THURSDAY THROUGH SATURDAY...CHANCE OF TSRA.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.
&&
.MARINE...
319 PM CDT
GENERALLY QUIET CONDITIONS OVER THE LAKE THROUGH THE WEEKEND WITH
RESPECT TO WINDS AND WAVES...AND PERIODS WHERE DIRECTIONS IN THE
NEARSHORE AREAS WILL BE CONTROLLED BY LAKE BREEZE INFLUENCES BY
DAY. A WARM AND MOIST AIR MASS WILL OVERSPREAD THE REGION AND
UPPER LEVEL DISTURBANCES COULD RESULT IN THUNDERSTORM COMPLEXES
CROSSING THE LAKE AT TIMES...MAINLY FROM WEDNESDAY NIGHT THROUGH
SATURDAY. THE POTENTIAL EXISTS FOR SOME OF THESE COMPLEXES TO
PRODUCE GUSTY WINDS AND LOCALLY HIGHER WAVES...AS WELL AS FREQUENT
CLOUD TO WATER LIGHTNING.
RC
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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[top]
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
833 PM CDT Tue Aug 19 2014
.UPDATE...
ISSUED AT 830 PM CDT TUE AUG 19 2014
Weak frontal boundary currently extending from northeast Illinois
through the Galesburg area to far northern Missouri. Earlier
convection has pushed well to the east and skies are now mostly
clear in our area, although some rogue thunderstorms have recently
developed along an outflow boundary across Clark County. Not any
appreciable change in temperature on either side of the front, but
dew points are slightly lower to the north. Front is not expected
to make much additional headway overnight. HRRR and RAP showing
some additional convection developing overnight on the tail of the
front across northern Missouri southeast to near St Louis.
Currently think the precip should stay to our southwest, but will
see an increase in clouds after midnight across the southwest CWA.
&&
.SHORT TERM...(This evening through Wednesday)
ISSUED AT 256 PM CDT TUE AUG 19 2014
19z/2pm surface analysis shows slow-moving cold front along the
Mississippi River. Isolated showers and thunderstorms are beginning
to develop immediately along the boundary within a narrow uncapped
instability axis. Further east, the air mass across much of central
Illinois remains capped in the wake of convection that moved across
the area earlier in the day. Will hold on to slight chance PoPs
through the early evening as the front makes its way slowly eastward
into the KILX CWA. Once daytime instability is lost, will go with a
dry forecast across the board overnight. With the boundary in the
vicinity, winds will become light/variable tonight, setting up the
possibility of fog. Forecast soundings suggest low-level moisture
will remain high, with both the MET and MAV guidance indicating
reduced visbys. Based on this guidance and a persistence forecast
from the past couple of nights, have included patchy fog after
midnight. Weak frontal boundary will remain in the area on
Wednesday, resulting in a continued slight chance for
showers/thunder, with afternoon highs climbing into the middle to
upper 80s.
&&
.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 256 PM CDT TUE AUG 19 2014
Wednesday night after midnight had previously looked like our best
chances of storms over the next few days, but the 12z guidance has
sped up the shortwave/MCV by 6-12 hours and weakened it. Our area
will still remain along the storm track over the building upper
level ridge, so despite lowering PoPs below the likely category,
chances will remain in most areas, with lowest chances southwest of
Springfield to Effingham.
The theme of higher storm chances in N-NE Illinois will continue for
the balance of the extended forecast, as the upper ridge and dome of
hot air build from southwest to northeast. The storm track appears
to generally follow the 588dm 500mb height line into this weekend.
We kept a narrow channel of chance PoPs across our N-NE counties
from Thursday to Saturday, with minor shifts east and west during
that time. Slight chances could extend as far south as Rushville to
Lincoln to Mattoon, but the building dome of heat should provide
enough mid-level capping to limit the southward extent of storms.
Model differences in the Sunday to Tuesday time frame have prompted
a continuation of periodic slight chance PoPs as a cold frontal
boundary tries to push into the dome of hot air. The 12z runs have
limited the forward progression of the front into IL on Sunday night
and Monday, when previous runs indicated an air mass change for less
hot conditions on Monday. Now the heat may linger as long as Tuesday
with the only hints of relief coming for areas north of I-74.
Heat index readings from Wednesday to Sunday will climb to into the
95F to 102F range at peak heating, which could be locally limited by
any pop-up thunderstorms each afternoon. Heat advisory levels are
105F+, but conditions will still be very uncomfortable, and heat
precautions will be necessary each day.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 623 PM CDT TUE AUG 19 2014
Thunderstorm activity has pushed east of the TAF sites early this
evening, and lingering diurnal clouds are quickly fading. Think
the night will be mostly clear. Still some concerns with fog
potential overnight, as despite the passage of a weak boundary,
moisture levels on either side are about the same and winds will
be light. Have maintained the lowest visibilities at KPIA, which
had some hefty rains earlier today and thus additional moisture to
feed any fog. After the light fog burns off in the 12-14Z time
frame, VFR conditions continue with ceilings mainly around 10KFT.
Cannot rule out an isolated shower, but probability too low to
include in the TAFs at this time.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEELHART
SHORT TERM...BARNES
LONG TERM...SHIMON
AVIATION...GEELHART
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1257 AM CDT MON AUG 18 2014
.DISCUSSION...
925 PM CDT
AN AREA OF STRATUS ACROSS SOUTHERN LAKE MICHIGAN AND IMMEDIATE
ADJACENT AREAS OF ILLINOIS AND INDIANA MUCH OF TODAY HAS EXPANDED
RAPIDLY SINCE SUNDOWN AND LOOKS TO ENCOMPASS MUCH OF IF NOT THE
ENTIRE FORECAST AREA BY EARLY OVERNIGHT. THIS IS EXPANDING IN
LIGHT NORTHEAST WIND FLOW UNDERNEATH A STRENGTHENING INVERSION.
ALL IN ALL A SETUP THAT SHOULD FAVOR IT TO CONTINUE AND RAP
SOUNDINGS SUPPORT THIS. VISIBILITY HAS TEMPORARILY BEEN UNDER 1SM
AT VALPARAISO AND EARLIER AT MICHIGAN CITY. AREAS OF DENSE FOG
WILL BECOME PROGRESSIVELY MORE LIKELY AS THE NIGHT
PROGRESSES...ESPECIALLY THOSE NOT UNDER THE PRESENT STRATUS. WITH
THE LIGHT WIND REGIME FOG SHOULD BE SLOW TO IMPROVE EARLY MONDAY
MORNING...PROBABLY IMPACTING THE MORNING COMMUTE IN PLACES. WILL
CONTINUE TO MONITOR IF A DENSE FOG ADVISORY WILL BE NEEDED. FOR
NOW HAVE BEEFED UP DENSE WORDING IN THE FORECAST AND HIGHLIGHTED
WITH GRAPHICAL NOWCAST.
MTF/CMS
//PREV DISCUSSION...
301 PM CDT
A WARMER...MORE HUMID...AND POTENTIALLY MORE UNSETTLED PATTERN IS ON
THE WAY FOR MUCH OF THE UPCOMING WEEK. MOISTURE CHANNEL IMAGERY
SHOWS THE UPPER LOW WHICH PROVIDED SOME SHOWER ACTIVITY YESTERDAY
MOVING MORE STEADILY ACROSS THE OHIO VALLEY. TO THE NORTH...A WAVE
IS MEANDERING EASTWARD ACROSS CENTRAL MINNESOTA WHILE A CLOSED UPPER
LOW SPINS OVER SOUTHERN MANITOBA. THIS TROUGH WILL DETERMINE THUNDER
CHANCES MONDAY NIGHT. ALSO OF NOTE IS A SERIES OF UPPER LOWS OVER
THE NORTHERN PACIFIC NEAR ALASKA. ENERGY FROM THESE SYSTEMS WILL
TRANSLATE INTO WESTERN/CENTRAL CANADA AND HELP FORCE UPPER RIDGING
OVER THE U.S. MIDWEST BRINGING THE AFOREMENTIONED WARM UP. AT THE
SURFACE...WEAK LOW PRESSURE IS OVER THE LOWER OHIO VALLEY IN
CONJUNCTION WITH THE UPPER LOW. ANOTHER WEAK LOW IS STRETCHED ACROSS
WESTERN MINNESOTA WHILE HIGH PRESSURE IS CENTERED OVER CENTRAL
ONTARIO. ANOTHER LOW IS OVER SOUTHERN MANITOBA IN CONJUNCTION WITH
THE BETTER ORGANIZED UPPER LOW IN THAT VICINITY.
TONIGHT...THE MAIN CONCERN TONIGHT WILL BE FOG/STRATUS AS RESIDUAL
LOW LEVEL MOISTURE LINGERS IN THE MIDST OF WEAK LOW LEVEL FLOW AND A
WEAK RIDGE AXIS. THE RIDGE AXIS WILL STRETCH ACROSS NORTHWEST AND
NORTH CENTRAL ILLINOIS BY MONDAY MORNING. WESTERN AREAS APPEAR TO BE
FAVORED FOR FOG DEVELOPMENT WHILE EASTERN AREAS MAY SEE MORE IN THE
WAY OF STRATUS...ESPECIALLY IF SOME EXISTING STRATUS IS UNABLE TO
ERODE INTO THE EVENING...ESPECIALLY NEAR THE LAKE. WILL INCLUDE FOG
MENTION IN THE FORECAST FOR MOST AREAS BUT THERE IS DECENT POTENTIAL
FOR DENSE FOG SO WILL NEED TO MONITOR THIS. WESTERN AREAS LOOK TO
HAVE THE BEST CHANCE FOR THIS AS THEY MAY CLEAR OUT THIS EVENING AND
BE IN CLOSEST PROXIMITY TO THE RIDGE AXIS.
MONDAY AND TUESDAY...THE UPPER WAVE OVER MINNESOTA WILL TRACK EAST
WITH ITS EFFECTS LARGELY STAYING TO THE NORTH OF THE AREA INTO
MONDAY MORNING...EXCEPT FOR SOME INCREASED MID AND HIGH LEVEL CLOUD
COVER. HOWEVER THE MANITOBA LOW WILL BE TRACKING EAST-SOUTHEAST
ACROSS THE NORTHERN PLAINS AND UPPER MISSISSIPPI RIVER VALLEY MONDAY
BEFORE SLOWING OVER THE WESTERN GREAT LAKES MONDAY NIGHT. THIS WILL
PUSH ASCENT INTO THE AREA AS EARLY AS LATE MONDAY AFTERNOON IN THE
NORTHWEST BUT MORE LIKELY MONDAY EVENING INTO MONDAY NIGHT. A MORE
FOCUSED SURFACE TROUGH AXIS IS FORECAST TO CROSS THE AREA SOME TIME
EARLY TUESDAY BRINGING THE MOST FOCUSED CHANCE FOR SHOWERS AND
THUNDERSTORMS ESPECIALLY ACROSS CENTRAL AND NORTHERN AREAS. LATEST
FORECAST GUIDANCE SHOWS QUITE A BIT OF SPREAD IN TERMS OF TIMING OF
THE BEST FOCUS FOR PRECIP. WILL CARRY HIGHEST POPS MONDAY EVENING
AND OVERNIGHT WITH LOWER POPS LATER TUESDAY AS FOCUS IS LOST BUT
UPPER CYCLONIC FLOW CONTINUES AROUND THE STALLED UPPER LOW TO THE
NORTH FOR THE MORNING. SOME MODEST WARMING WILL OCCUR ALOFT MONDAY
BUT PERIODIC BOUTS OF MID CLOUD MAY HELP LIMIT TEMPS SOMEWHAT...NOT
TO MENTION IMPACT OF ANY MORNING STRATUS/FOG. FLOW WILL CONTINUE OFF
THE LAKE KEEPING LAKESHORE AREAS COOLEST. WILL CARRY HIGHS IN THE
LOW TO MID 70S LAKESIDE AND AROUND 80 INLAND MONDAY WITH SOUTH TO
SOUTHWEST WINDS TUESDAY ALLOWING TEMPS TO REACH THE LOWER 80S FOR
MOST PLACES UNLESS PRECIP TIMING SLOWS AND LINGERS THROUGH MORE OF
THE DAY.
WEDNESDAY INTO THE WEEKEND...A LARGER UPPER TROUGH WILL AMPLIFY OVER
WESTERN CANADA INTO WEDNESDAY AS ANOTHER UPPER LOW DROPS SOUTHWARD
DOWN THE CALIFORNIA COAST AND CUTS OFF. THIS WILL LEAD TO
AMPLIFICATION OF AN UPPER RIDGE ACROSS THE HIGH PLAINS TUESDAY WHICH
WILL QUICKLY SHIFT EAST INTO THE CENTRAL U.S. WEDNESDAY. THIS WILL
BRING A PUSH OF WARM ADVECTION ACROSS THE AREA WEDNESDAY WHICH MAY
BE ENOUGH TO KICK OFF SOME SHOWERS AND STORMS. WITH THE COMPLEX
TROUGH PATTERN TO THE WEST THERE WILL BE THE TENDENCY FOR SHORTWAVES
TO TRAVERSE THE RIDGE WITH SOME POTENTIAL FOR THIS TO BEGIN
WEDNESDAY BUT IT APPEARS MORE LIKELY TO BEGIN WEDNESDAY NIGHT. THE
RIDGE WILL PARK ITSELF OVER THE MIDWEST/WESTERN LAKES INTO FRIDAY
KEEPING THE LIKELIHOOD OF SHORTWAVES TRACKING THROUGH THE FLOW RATHER
HIGH. THE TRACK OF THESE WILL DEPEND ON HOW AMPLIFIED THE RIDGE
BECOMES BUT LATEST GUIDANCE CONTINUES TO KEEP THE LOCAL AREA IN A
FAVORED ZONE FOR THESE WAVES. THE AIRMASS WILL BECOME VERY MOIST BY
THURSDAY WITH PRECIPITABLE WATER VALUES PUSHING/TOPPING 2 INCHES.
BETWEEN THE POTENTIAL WAVES AND THE VERY MOIST AIRMASS SEVERAL
ROUNDS OF THUNDERSTORMS MAY AFFECT THE FORECAST AREA FROM LATER
WEDNESDAY THROUGH FRIDAY. IF THE AIRMASS BECOMES AS MOIST AS
EXPECTED THEN ANY STORM WILL HAVE A GOOD CHANCE TO BRING HEAVY
RAINFALL. RAINFALL POTENTIAL WILL NEED TO BE WATCHED CLOSELY OVER
THE NEXT SEVERAL DAYS ESPECIALLY IF MULTIPLE ROUNDS LOOK MORE
LIKELY. THIS RIDGE LOOKS TO AMPLIFY NORTHWARD SATURDAY PUSHING THE
FAVORED STORM TRACK TO THE NORTH. EVOLUTION BEYOND SATURDAY IS MORE
UNCERTAIN AND WILL BE DRIVEN BY THE MOVEMENT OF THE LARGE UPPER
TROUGH OVER NORTHERN U.S. AND CANADIAN ROCKIES. GUIDANCE IS IN
DISAGREEMENT ON HOW QUICKLY THIS OCCURS. OTHERWISE...HIGHS WILL WARM
FROM MIDWEEK INTO THE WEEKEND AS WILL HUMIDITY LEVELS. THE WILD CARD
WILL BE THUNDERSTORMS WITH THEIR TIMING AND LINGERING EFFECTS SUCH
AS CLOUD COVER PLAYING A KEY ROLE IN HOW WARM THINGS GET. MINIMAL
THUNDER IMPACT WOULD RESULT IN HIGHS IN THE MID AN UPPER 80S BY
THURSDAY WITH 90 POSSIBLE...ESPECIALLY IF THE RIDGE AMPLIFIES MORE
THAN CURRENTLY THOUGHT.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* IFR CIGS INTO MONDAY MORNING...OCNL LIFR POSSIBLE.
* NORTHEAST WINDS BECOMING LGT/VRBL OVERNIGHT AND THROUGH LATE
MONDAY MORNING.
* SSWLY WINDS TURNING EAST WITH THE PASSAGE OF A LAKE BREEZE.
SPEEDS APPROACHING 10 KT LATE MONDAY AFTERNOON.
* SHRA LIKELY LATE MONDAY EVENING AND CHANCE TSRA LATE MONDAY
NIGHT.
KREIN
//DISCUSSION...UPDATED 06Z...
AN AREA OF LOW STRATUS HAS SPREAD ACROSS NERN IL/NWRN IN WITH
PREVAILING IFR/LIFR CIGS. AT ISSUANCE TIME...THE ONLY TAF SITE NOT
UNDER THE STRATUS DECK WAS RFD...WHICH REMAINED UNDER MOSTLY CLEAR
SKIES. LATEST SATELLITE IMAGERY SHOWS THAT THE LEADING EDGE OF THE
STRATUS IS STEADILY MOVING WEST AND ANTICIPATE THAT IT SHOULD
OVERSPREAD RFD BTWN 07-08Z. CIGS THERE SHOULD QUICKLY DROP TO IFR
LEVELS AS WELL. WITH A GREATER PERIOD OF CLEAR SKIES AND LIGHTER
WINDS...RFD ALSO HAS THE POTENTIAL FOR VSBY TO DROP INTO IFR
RANGES AS WELL. THE CHICAGO AREA TAF SITES ARE LESS LIKELY TO SEE
SUCH VISBY RESTRICTIONS AS THE AREA HAS BEEN UNDER PERSISTENT
STRATUS COVER AND HAS SEEN SLOWER COOLING TONIGHT AS WELL AS WIND
SPEEDS REMAINING HIGHER...GENERALLY ARND 6-8KT OVERNIGHT.
FOR THE DAYTIME HOURS TOMORROW...THERE WILL BE 2 CONCERNS...THE
TIMING OF CIGS IMPROVING AND THE TIMING OF A LAKE BREEZE BOUNDARY
PUSHING INLAND. AS FOR THE CIGS...ANTICIPATE THAT DAYTIME
INSOLATION SHOULD ALLOW FOR CIGS TO BURN OFF AND IMPROVE TO VFR BY
EARLY AFTERNOON. WITH A VERY WEAK PRESSURE GRADIENT IN
PLACE...WINDS SHOULD BE LGT/VRBL THROUGH LATE MORNING...BECOMING
SSWLY UP TO 8KT FROM LATE MORNING THROUGH EARLY AFTERNOON. THE
COMBINATION OF A WEAK GRADIENT AND DIFFERENTIAL HEATING BETWEEN
LAND...FOLLOWING THE STRATUS BURN OFF...AND THE WATER...A LAKE
BREEZE SHOULD DEVELOP. THE LATEST HIGH RES MODEL GUIDANCE SUGGESTS
THAT THE LAKE BREEZE SHOULD PUSH THROUGH ORD/MDW BY ARND 21-22Z.
THE NEXT CONCERN WILL BE TIMING OF PCPN MOVING INTO THE AREA
ASSOCIATED WITH A STRONG MID LEVEL SHORTWAVE. THE LATEST MODEL
GUIDANCE SUGGESTS THAT SOME SHOWERS COULD MOVE INTO THE RFD AREA
AS EARLY AS THE LATE AFTERNOON OR EARLY EVENING HOURS WITH THE
BETTER CHANGES FOR THUNDER DURG THE LATE EVENING HOURS AND THEN
SPREADING TO THE CHICAGO AREA TERMINALS BY AROUND MIDNIGHT. THIS
SHOULD BE A SLOW MOVING FEATURE AND IS EXPECTED TO STRENGTHEN
THROUGH THE NIGHT...SO THE PERIOD OF SHRA/TSRA COULD POSSIBLE LAST
THROUGH THE EARLY MORNING HOURS.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH IN IFR CIGS THROUGH DAYBREAK...LOWER THAT CIGS COULD LOWER
TO LIFR LEVELS.
* MEDIUM IN WIND SPEED MONDAY AND TIMING OF THE WIND SHIFT TO ELY
FOLLOWING THE PASSAGE OF THE LAKE BREEZE.
* MEDIUM TO HIGH FOR A PERIOD OF SHRA/TSRA MONDAY NIGHT...BUT LOW
IN THE TIMING OF IMPACT AT THE TERMINALS.
KREIN
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY...TSRA LIKELY...ESPECIALLY DURING THE MORNING.
WEDNESDAY-SATURDAY...PERIODIC CHANCES OF TSRA.
MTF
&&
.MARINE...
150 PM CDT
A COLD FRONT HAS CLEARED THE SOUTHERN TIP OF THE LAKE...AND NORTH TO
NORTHEAST WINDS HAVE OVERSPREAD LAKE MICHIGAN WITH HIGH
PRESSURE OVER SOUTHERN ONTARIO AND LOW PRESSURE IN FAR SOUTHERN
ILLINOIS. EXPECT WAVES TO BUILD GENERALLY INTO THE 2 TO 4 FT
RANGE OVER THE SOUTHERN HALF OF THE LAKE BEFORE EASING SOME LATE
TONIGHT. BOTH THE CANADIAN HIGH AND THE LOW IN SOUTHERN ILLINOIS
WILL WORK THEIR WAY EASTWARD TONIGHT INTO MONDAY WHICH WILL
SLACKEN THE WINDS AND VEER THEM TO MORE OF AN EASTERLY DIRECTION
TONIGHT THAN SOUTH TO SOUTHEASTERLY ON MONDAY. ANOTHER WEAK LOW
PASSING THROUGH THE CANADIAN PRAIRIES WILL WORK ITS WAY SE TOWARD
THE NORTHERN HALF OF THE LAKE ON TUESDAY AND SLOWLY DRIFT EAST ON
WEDNESDAY. AFTER A PERIOD OF HIGH PRESSURE...A SERIES OF WEAK LOWS
WILL MIGRATE EASTWARD OUT OF THE PLAINS TOWARD THE LAKE FOR THE
LATTER HALF OF THE WEEK. KMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014 UNTIL 4 AM MONDAY.
IN...BEACH HAZARDS STATEMENT...INZ001-INZ002 UNTIL 4 AM MONDAY.
LM...NONE.
&&
$$
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Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1158 PM CDT Sun Aug 17 2014
.UPDATE...
ISSUED AT 902 PM CDT SUN AUG 17 2014
Only a few remaining showers in SE Illinois this evening as lift
associated with the recent storm system diminishes as the low
moves off to the east. The air mass left behind in central/SE
Illinois remains quite moist at the surface with dewpoints in the
upper 60s to around 70 and near saturated conditions up to around
750 mb. Skies clearing above will allow for good radiational
cooling which will bring temperatures rapidly down to the
dewpoint. Fog will become prevalent overnight as a result.
Forecasts reflect this well, and will be keeping an eye on the
potential for dense fog formation. The mitigating factors are the
steady light northeast winds which will keep the surface layer
mixed, and the depth of the fog layer may preclude dense fog
formation later in the night. So far, updates have been sent to
account for trends on shower activity, temperature, humidity, and
winds and later updates may be sent as fog trends become more
definite.
&&
.SHORT TERM...(This evening through Monday)
ISSUED AT 259 PM CDT SUN AUG 17 2014
Surface low has dropped into far southern Illinois early this
afternoon with remnant MCV still evident on radar imagery over the
far southeast CWA. This is where most of the lingering showers are
continuing, with a few as far north as Taylorville and Tuscola. Some
thinning of the low clouds has been developing but skies still
mainly cloudy.
Main concern for this part of the forecast is with fog potential
tonight. Cloudiness across far northern Illinois and southeast Iowa
is more cellular in nature and should diminish with loss of daytime
heating. Latest RAP guidance showing the northern CWA becoming
partly cloudy this evening. With northeast flow continuing, not a
lot of drying will take place in the lower levels with dew points
upstream still in the mid 60s in many areas. This should allow
visibilities to start dropping by late evening across the north.
Model guidance showing a fair range as to how extensive or thick the
fog gets, so for now will only mention patchy or areas of fog in the
grids for late tonight and early Monday. Skies expected to become
partly to mostly sunny by midday as forecast soundings are rather
dry.
In terms of the lingering showers, most of what`s left in our area
is along a weak trough axis dropping into southern Illinois, aided
by the upper low which is currently located in far southwest
Indiana. Am expecting the showers to fade early this evening as the
low pulls away. On Monday, have maintained some isolated showers/
storms across the eastern CWA during the afternoon as a weak wave
passes through the area.
&&
.LONG TERM...(Monday night through Sunday)
ISSUED AT 259 PM CDT SUN AUG 17 2014
Monday night will feature an upper trough and weak surface low
tracking from the upper midwest into the western Great Lakes, with a
cold front extending south into northern Illinois. Rain chances will
return to areas NW of the I-55 later Monday evening, with chances
expanding to Indiana along and north of I-72 by 12z/7am Tuesday.
Better forcing from the 500mb vort max should remain in northern IL,
but moisture convergence along the front and a weak 300mb jet max
overhead could provide just enough lift for a few storms with the
front. No severe weather is expected, especially with limited
instability overnight.
Tuesday should see a decreasing trend in rain/storm chances in the
afternoon as the bulk of the mid and upper level energy departs to
the east. The break in the rain should continue Tues night for all
but the far southwest KILX CWA, from Jacksonville to Effingham,
where a warm front will quickly approach the area. Rain/storm
chances will remain mainly southwest of Havana to Lincoln to
Shelbyville on Wednesday as the front slowly pushes into IL.
That warm front is expected to usher in a progressively warmer
airmass the remainder of the week and into the weekend. Wednesday
night, an MCV is projected to move from N Iowa across N Illinois,
with enough support from strong mid level warm air advection and a
low level jet across central IL to trigger showers/storms across most
of our forecast area.
Low surface pressure and a stalled frontal boundary are still
expected across northern Illinois for Thursday, keeping rain chances
going into Thursday night. The front is expected wash out Thursday
night as warming continues through a deep layer of the atmosphere.
The warming at mid levels will eventually work to cap the atmosphere
and limit storm potential, despite ample low level moisture. A
shortwave is forecast by the ECMWF to move from Nebraska across N
Illinois Saturday, which could affect our northern counties with a
few storms, depending on the extent of elevated CAPE above the
capping inversion.
The ECMWF is also showing a cold frontal passage following the
shortwave on Saturday night, bringing a period of storms and
slightly cooler air for Sunday. The GFS keeps the upper level ridge
entrenched over IL, limiting much storm potential by keeping
shortwave tracks north of central IL. It also has much warmer
conditions continuing into Sunday. Confidence remains low on the
scenario for next weekend due to the differences.
Heat and humidity levels will climb the last half of the week, as
highs reach into the lower 90s south of Lincoln to Mattoon Thurs
through Saturday. Dewpoints in the low to mid 70s will help push
heat index readings into the upper 90s to around 100 in at least the
south half of the KILX CWA.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
ISSUED AT 1158 PM CDT SUN AUG 17 2014
MVFR vsby has become predominant with local IFR/LIFR
cigs/vsby over central and SE Illinois as fog begins to develop
this evening. Overnight, fog will develop, with potential for
LIFR or VLIFR conditions...mainly 07Z-15Z. So far, steady light NE
winds 5-10 kts has kept fog diffuse through mixing of the surface
layer, but winds should decrease overnight as pressure gradients
relax across the region. Improving conditions after 15Z with
ceilings becoming sct-bkn030 for most of the afternoon. A weak
trough and surface low moving in from the NW Monday evening will
bring a chance of rain back to areas KPIA-KBMI northward after
00Z, but chances for significant vsby/cig reduction in precipitation
remain too low for mention in central IL TAFs at this time.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...ONTON
SHORT TERM...GEELHART
LONG TERM...SHIMON
AVIATION...ONTON
AREA FORECAST DISCUSSION
NWS TOPEKA KS
607 PM CDT Tue Aug 19 2014
...AVIATION UPDATE...
.SHORT TERM...(This Evening through Wednesday)
Issued at 342 PM CDT TUE AUG 19 2014
An upper level trough was moving east across the upper Midwest and
mid MS river valley late this afternoon. An upper level ridge across
NM and CO will build east across the plains tonight and east into
the lower and mid MS river valley by late Wednesday afternoon.
Any convective complexes that form across the central and northern
high plains this evening should move well north of the CWA tonight.
Isentropic lift will cause elevated storms to form across southeast
SD and eastern NE but these storms will move east into IA.
Wednesday will be mostly sunny and warm as the upper level ridge
axis moves east across the state of KS. Highs will reach the mid to
upper 90s, with highs of 100 degrees possible across the southwest
counties of the CWA. Deeper mixing across the western counties
should cause dewpoints to drop into the mid 60s during the afternoon
hours. The northeast counties may keep lower 70 dewpoints through
the afternoon hours but high temperatures will be slightly cooler in
the mid 90s. Heat indices will range from 100 to 104 degrees across
the CWA during the afternoon hours.
.LONG TERM...(Wednesday Night through Tuesday)
Issued at 342 PM CDT TUE AUG 19 2014
The GFS is the only model hinting at clipping the far northwest
county warning area with convection Wednesday night despite forecast
soundings showing inhibition aloft through the night. Will therefore
maintain a dry forecast through Thursday morning as the shortwave
helping to develop precip should pass well north and west of the
CWA. Another shortwave trough over the southern Rockies will move
northeast and bring a chance for thunderstorms to the northwest
third of the CWA Thursday night...although again the better chances
will remain well north and west of the CWA.
Following this wave...the ridging with the upper level high will
undergo amplification as the stronger shortwave trough begins to
rotate out of the case of the western trough and into the
central/southern Rockies. Although this should keep the CWA dry and
hot on Friday...it may allow for some of the high plains convection
that forms late in the day to spread east and northeastward and
briefly clip the CWA Friday night. Highs Thursday through Saturday
will generally be in the middle to upper 90s.
Models differ some with the overall timing/speed of the final
shortwave to rotate out through the western trough and into the
central plains next week. However they are similar in bringing the
western trough slowly eastward into the ridge and gradually
flattening it with time. This will result in one front moving into
the CWA by Monday with a second arriving by Wednesday. This will
keep the chances for showers and thunderstorms across most of the
area Sunday thru Tuesday. With more clouds...precip chances and
initial front...cooled high temperatures slightly for now into the
80s and lower 90s. At the same time...cooled lows in the middle 70s
Thursday and Friday into the 60s by Monday and Tuesday.
&&
.AVIATION...(For the 00Z TAFs through 00Z Wednesday Evening)
Issued at 607 PM CDT TUE AUG 19 2014
Aside from the RAP that brings some nocturnal convection into
northern KS, most other guidance keeps the storms north of the
state line. With isentropic surfaces showing the better
convergence from the low level jet remaining north of the
terminals, will continue with a VFR forecast. Both the RAP and NAM
show a nocturnal inversion developing with 30 to 40 KTS just above
the boundary layer. There are mixed signals as to the strength of
the inversion and the impact of the low level jet, however felt
there was enough evidence for possible LLWS to include it in the
forecast overnight.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...Gargan
LONG TERM...63
AVIATION...Wolters
AREA FORECAST DISCUSSION
NWS TOPEKA KS
358 PM CDT Mon Aug 18 2014
.SHORT TERM...(This Evening through Tuesday)
Issued at 352 PM CDT MON AUG 18 2014
The center of an upper level trough was located across eastern ND
late this afternoon with an upper level trough axis extending
southwest across central SD. The numerical models show this upper
level trough digging southeast across southern MN and eastern NE
into northern MO. The southwest section of the upper trough will
move southeast across northeast KS between 6Z and 12Z. The NAM,
GFS and ECMWF forecast QPF across northeast and east central KS
later Tonight, with the ECMWF and NAM showing most of the CWA with
QPF. The NAM model shows weak isentropic lift at the 310K level
with LFCs around 700mb. The most intense isentropic lift at the
310K level will be across northern MO and IA.
The mesoscale models, consisting of the ARW, NMM and HRRR do not
forecast any QPF across the CWA tonight. I will probably keep slight
chance to chance pops across much of the CWA, since the ascent ahead
of the H5 trough combined with isentropic lift should allow elevated
thunderstorms to develop across the northeast counties of the CWA
around midnight, then building southwest across the central and
southwest counties of the CWA through the early morning hours before
spreading southeast across much of east central KS by 12Z TUE.
Any lingering elevated thunderstorms, if they do develop, will shift
southeast of the CWA during the mid morning hours. Skies should
clear through the late morning and early afternoon hours and
temperatures will warm into the lower to mid 90s. If there is a
leftover outflow boundary across the northeast counties, then
temperatures along the NE border may only reach into the upper 80s.
I placed in 14 pops in case there is enough surface convergence for
an isolated thunderstorm during the afternoon hours.
.LONG TERM...(Tuesday Night through Monday)
Issued at 352 PM CDT MON AUG 18 2014
Models are in agreement that heights rises and resulting warm air
advection will be situated across the northeast corner of the county
warning area Tuesday evening providing another chance for
thunderstorms. As this area focuses further northward through the
night...have removed pops this area after midnight. Will keep lows
mild in the low to middle 70s. This will then set the stage for
mostly sunny very warm...breezy day on Wednesday. Highs will
generally be 95 to 100 degrees with the warmest in the Abilene area
and the coolest near Hiawatha.
As the upper ridge builds across the southern plains...expect dry
weather across the cwa Wednesday night through Thursday. However...
with south winds continuing...highs Thursday will again be in the
middle to upper 90s.
As the cutoff upper trough in the desert southwest gets picked up by
Thursday and heads into the central and northern high plains into
the weekend...there will be better chances for thunderstorms across
the area...although the northern/northwest 1/2 of the cwa will be
the more likely areas to see rain. Do not expect a frontal passage
until during the day Sunday...so may not see highs temps below 90
degrees until Monday when readings in the middle to upper 80s should
be the rule.
&&
.AVIATION...(For the 18Z TAFs through 18Z Tuesday Afternoon)
Issued at 1237 PM CDT MON AUG 18 2014
Expect VFR conditions across the terminals through the next 24
hours. An isolated thunderstorm may affect the terminals between
6Z and 12Z TUE. At this time confidence is not high enough to
include in TAFS.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Gargan
LONG TERM...63
AVIATION...Gargan
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
230 PM CDT Mon Aug 18 2014
...UPDATE TO LONG TERM...
.SHORT TERM...(This evening through Tuesday)
ISSUED AT 1202 PM CDT MON AUG 18 2014
There is a high pressure ridge over Colorado south into New Mexico
late this afternoon. A lee side trough is near the Kansas and
Colorado border, and a warm front has been pushing northeast
through western Kansas this morning. The forecast is on track for
today, with highs just over 100F degrees likely somewhere across
southern and western Kansas, and upper 90s in our northern zones.
There could be a few and far between showers and isolated
thunderstorms just about anywhere late today. The HRRR model shows
a few thunderstorms across our south and southeast zones after
21z, but the NAM and NAMNG5 models are showing storms first over
our west and then moving across the northern CWA. Mid and high
clouds will be on the increase late this afternoon and evening.
So, the low Pops in the 17-20 percent range blanketing our
forecast area seem reasonable. Time will tell on which model is
more correct.
The same HRRR, NAM, and NAMNG5 models decrease the measurable
precip after 04Z, and then the clouds will slowly dissipate after
09Z or so. I plan to reduce 20 percent Pops rapidly between 06Z and
12Z. Not much precipitation will fall either, as any convection
will be high based. I used the QPF_from_PoP application, and it
only shows 0.01 to spotty 0.03 inches of rain overnight. With
clouds breaking late and perhaps a little rain, minimum temperatures
should end up in the middle 60s in Syracuse, Scott City, and
Wakeeney, while settling only to around 70F degrees in the Meade,
Coldwater and Medicine Lodge areas. Winds will continue to hover
at less than 10 MPH tonight.
On Tuesday, the surface low will advect into central Kansas, and the
front will sag south across part of our CWA. Thus, Max temps should
dip just a little north of the front, while south along the Oklahoma
border near Medicine Lodge, it should warm up to around 100F. Winds
on Tuesday will be breezy from the south in the 15 to 25 mph and
gusty range. I do not think there will any precipitation on
Tuesday, as the lower max temps will result in less instability than
today.
.LONG TERM...(Tuesday night through Monday)
ISSUED AT 225 PM CDT MON AUG 18 2014
Medium range models indicate an upper level ridge of high pressure
transitioning eastward out of the Western High Plains into the
Central Plains to begin the period Tuesday night. Combined with
a weak flow aloft, drier conditions are likely to prevail through
late Wednesday afternoon. Meanwhile, an upper level trough will dig
southeast across southern California Wednesday setting up a strong
southwest flow aloft across the Central and Southern Rockies,
including a +90kt jet core projected to lift northeast out of the
Desert Southwest into the Colorado Rockies. With a prevailing lee
side trough providing increased convergence in the lower levels,
thunderstorm development is likely across portions of eastern
Colorado Wednesday afternoon with a few storms potentially
drifting into western Kansas later in the evening through early
Thursday. However, the weaker flow aloft across western Kansas
will limit the strength and coverage of any storms. The upper
level shortwave will then lift northeast going into the weekend
while a large scale upper level high remains locked in across the
Deep South. Although precip chances will remain present virtually
each day into the weekend, the weaker flow aloft will limit storm
development, strength, and coverage.
Temperatures will remain above normal Wednesday as the
aforementioned upper level ridge shifts east across the Central
Plains. A prevailing southerly flow across western Kansas will
reinforce the warmer air mass already in place across the region
with H85 temperatures ranging from the upper 20s(C) in central
Kansas to around 30C closer to the Colorado border. As lower level
lapse rates steepen into the afternoon, look for highs well up
into the 90s(F) to near 100F Wednesday. Similar temperatures are
then expected each day through Saturday as the low level southerly
flow persists into the early part of the weekend.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 1137 AM CDT MON AUG 18 2014
With building high pressure from the west and weak high pressure
aloft centered southwest of Kansas, there will very few clouds
overhead and light surface winds through the next 24 hours. There
will be just enough instability for a few showers and isolated
thunderstorms late this afternoon and overnight, but there is not
enough confidence to put convection into the TAFS. VFR conditions
should dominate for most of this TAF period.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 69 97 71 99 / 20 10 0 10
GCK 67 96 70 98 / 30 10 0 10
EHA 66 95 68 98 / 20 10 0 20
LBL 66 96 71 98 / 20 10 0 10
HYS 68 98 71 99 / 20 10 0 10
P28 70 98 74 99 / 20 10 0 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Burke
LONG TERM...JJohnson
AVIATION...Burke
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
100 PM CDT Mon Aug 18 2014
...Updated for the short term discussion...
.SHORT TERM...(This evening through Tuesday)
ISSUED AT 1202 PM CDT MON AUG 18 2014
There is a high pressure ridge over Colorado south into New Mexico
late this afternoon. A lee side trough is near the Kansas and
Colorado border, and a warm front has been pushing northeast
through western Kansas this morning. The forecast is on track for
today, with highs just over 100F degrees likely somewhere across
southern and western Kansas, and upper 90s in our northern zones.
There could be a few and far between showers and isolated
thunderstorms just about anywhere late today. The HRRR model shows
a few thunderstorms across our south and southeast zones after
21z, but the NAM and NAMNG5 models are showing storms first over
our west and then moving across the northern CWA. Mid and high
clouds will be on the increase late this afternoon and evening.
So, the low Pops in the 17-20 percent range blanketing our
forecast area seem reasonable. Time will tell on which model is
more correct.
The same HRRR, NAM, and NAMNG5 models decrease the measurable
precip after 04Z, and then the clouds will slowly dissipate after
09Z or so. I plan to reduce 20 percent Pops rapidly between 06Z and
12Z. Not much precipitation will fall either, as any convection
will be high based. I used the QPF_from_PoP application, and it
only shows 0.01 to spotty 0.03 inches of rain overnight. With
clouds breaking late and perhaps a little rain, minimum temperatures
should end up in the middle 60s in Syracuse, Scott City, and
Wakeeney, while settling only to around 70F degrees in the Meade,
Coldwater and Medicine Lodge areas. Winds will continue to hover
at less than 10 MPH tonight.
On Tuesday, the surface low will advect into central Kansas, and the
front will sag south across part of our CWA. Thus, Max temps should
dip just a little north of the front, while south along the Oklahoma
border near Medicine Lodge, it should warm up to around 100F. Winds
on Tuesday will be breezy from the south in the 15 to 25 mph and
gusty range. I do not think there will any precipitation on
Tuesday, as the lower max temps will result in less instability than
today.
.LONG TERM...(Tuesday through Sunday)
ISSUED AT 358 AM CDT MON AUG 18 2014
Upper level troughing will gradually build across the northwestern
United States trough Friday, with upper level ridging across the
southern Plains. This pattern is conducive to weak lee troughing
over the high plains and mainly hot and dry weather across
southwestern Kansas. High temperatures will generally be between 96
and 100F each day, with lows from the upper 60s in far western
Kansas to the mid 70s farther east. There are small chances for
thunderstorms somewhere across western Kansas just about every day
from Wednesday to Friday ahead of the lee trough. The best chance
of severe thunderstorms will be to the northeast of southwest
Kansas where rich low level moisture will reside. However,
damaging wind gusts can not be ruled out this time of year when
it gets hot, with high dewpoint depressions.
There is some disagreement as to the arrival of the upper level
trough as it approaches the central and northern plains sometime
between Saturday night and Monday. The GFS/GEM/UKMET are faster
while the ECMWF is quite a bit slower. A faster solution would
result in better chances for thunderstorms as early as late Saturday
while the slower solution would delay the more widespread
thunderstorm activity until late Sunday. The cold front arrival
also hinges on the speed of the system, with cooler weather arriving
either Sunday or Monday.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 1137 AM CDT MON AUG 18 2014
With building high pressure from the west and weak high pressure
aloft centered southwest of Kansas, there will very few clouds
overhead and light surface winds through the next 24 hours. There
will be just enough instability for a few showers and isolated
thunderstorms late this afternoon and overnight, but there is not
enough confidence to put convection into the TAFS. VFR conditions
should dominate for most of this TAF period.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 100 69 97 72 / 20 20 10 10
GCK 99 67 96 71 / 20 30 10 10
EHA 99 66 95 69 / 20 20 10 10
LBL 100 66 96 72 / 20 20 10 10
HYS 98 68 98 72 / 20 20 10 10
P28 100 70 98 75 / 20 20 10 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Burke
LONG TERM...Finch
AVIATION...Burke
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1240 AM CDT Mon Aug 18 2014
.UPDATE...
Issued at 812 PM CDT SUN AUG 17 2014
Monitoring two MCS complexes tracking southeast over southern
Nebraska and north central Kansas. The Nebraska cluster maintains
a strong outflow boundary around 50 MPH gusting out ahead of the
main line showing a history of 60 to 70 mph winds. Thunderstorm
cluster in Kansas has recently reported wind gusts near 60 mph.
Environment ahead of the system is characterized currently by 3500
J/KG of MLCAPE and effective shear increasing to near 30 KTS as a
southwesterly LLJ ramps up over north central Kansas. Current thinking
is similar to latest runs of the HRRR depicting the two clusters
converging as they track south and east over the CWA. Have therefore
increased precip chances over north central Kansas. Instability gradient
weakens towards central and eastern portions of northeast Kansas
and would expect the cluster to weaken in severity between
midnight and 7 AM. Between now and midnight, slight risk of severe
weather was expanded across north central areas where wind gusts
between 50 and 60 mph and small hail are possible.
&&
...Update to aviation forecast discussion...
.SHORT TERM...(This Evening through Monday)
Issued at 343 PM CDT SUN AUG 17 2014
Water vapor imagery showing next shortwave trough and associated
frontal boundary moving thru northwest NE. Thunderstorms have
developed over north central NE and should propagate southeastward
within moisture axis situated across central NE into far northern
KS that will lift slowly northward through the night. Expect NE
convection to weaken later this evening with the loss of heating and
weaker shear further south towards the KS border. Will still however
keep the high chance pops near the NE border and decrease southward
in weaker warm air advection. The most likely period will be near
the state line towards sunrise in the far northeast corner. Lows
tonight will be in the middle to upper 60s. More mixing and
increasing clouds should limit fog potential tonight.
Front to the north will move southeast and bisect the cwa northeast
to southwest by mid to late afternoon. Axis of higher cape will set
up along and ahead of the front. Although the shear along the front
will not be as strong as further north and a capping inversion will
be in place...expect afternoon heating and weak convergence along
the front to allow at least some isolated thunderstorms to develop.
If they do...a deeply mixed atmosphere with temps well into the
middle and upper 90s would favor potential strong wind gusts with
any convection that forms. Will keep highest chance pops along and
ahead of the front...or primarily just north and west of the
Turnpike.
.LONG TERM...(Monday Night through Sunday)
Issued at 343 PM CDT SUN AUG 17 2014
Expect scattered convection Monday evening as the frontal along the
frontal boundary as it slowly moves southeast. NAM showing MUCAPE
around 5000 J/KG with around 35 to 40kts of bulk shear into the
early evening hours. Could see a few strong to severe storms with
strong wind gusts the main hazard. The front should sag south of the
CWA Tuesday morning before moving northward as a warm front Tuesday
afternoon and Tuesday night. Isentropic lift over the warm front
should generate elevated thunderstorms mainly across the northern
CWA. Areas near Highway 36 will have a small chance of morning
thunderstorms on Wednesday.
Wednesday night through Saturday will see ridge building over the
Southern and Central Plains. Periodic waves will move through the
flow and models differ on timing and resultant precipitation
placement. Will continue with low end chances of precipitation,
mainly nocturnal. GFS and ECMWF diverge with the timing of an upper
level trough with the GFS keeping the upper trough over the western
states while the ECMWF is much further east over the central U.S..
Will go dry on Sunday given the large differences for now.
Temperatures will be above normal through much of the period.
&&
.AVIATION...(For the 06Z TAFs through 06Z Monday Night)
Issued at 1233 AM CDT MON AUG 18 2014
Remnant cluster of TSRA gradually dissipating over KMHK while gust
front is progged to reach KTOP/KFOE just before 06Z. Gusty winds
prevail through at least 09Z before becoming light and variable.
Models having difficulty handling cloud cover and TSRA with the
HRRR showing some confidence in cluster diminishing south of
KTOP/KFOE. Mentioned VCTS after 07Z in case scattered convection
reforms near terminals. BKN mid level deck lingers through mid
morning before mixing increases south winds during afternoon.
Another round of TSRA possible towards 00Z, however timing and
location still uncertain for mention.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Bowen
SHORT TERM...63
LONG TERM...53
AVIATION...Bowen
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1105 PM MDT SUN AUG 17 2014
.SHORT TERM...(THIS AFTERNOON THROUGH MONDAY)
ISSUED AT 121 PM MDT SUN AUG 17 2014
EARLY AFTERNOON WV IMAGERY AND RAP ANALYSIS CONTINUE TO SHOW
PERSISTENT RIDGE IN PLACE ACROSS THE SW US. A SHORTWAVE TROUGH IS
EVIDENT OVER NORTHERN COLORADO...WITH H7 TROUGH ON LATEST RAP JUST
OVER THE CENTRAL ROCKIES. RADAR AND VIS SATELLITE SHOW ISOLATED TO
WIDELY SCATTERED THUNDERSTORMS ALREADY DEVELOPING ALONG SURFACE
TROUGH AXIS AHEAD OF UPPER TROUGH OVER OUR SW CWA.
HRRR HAS A REASONABLE HANDLE ON CURRENT COVERAGE AND INDICATED
ACTIVITY MAINLY REMAINING ALONG AND EAST OF A TRIBUNE TO FLAGLER
LINE. MODERATE INSTABILITY IS IN PLACE WITH ML CAPE IN THE 1500-
3000 J/KG RANGE. CIN IS STILL HIGH ACROSS THE EASTERN HALF OF THE
CWA...HOWEVER AS SHORTWAVE TROUGH MOVES EAST LATER THIS AFTERNOON
AND EVENING ML CINH SHOULD WEAKEN ALLOWING FOR ACTIVITY TO SPREAD
EASTWARD. COVERAGE IS STILL A QUESTION WITH DRY INVERTED V TYPE
MOISTURE PROFILES...HOWEVER WITH LARGE SCALE FORCING INCREASE AND
GOOD BL MOISTURE IN PLACE WE SHOULD BE ABLE TO SEE SCATTERED
ACTIVITY DEVELOP. THERE IS AT LEAST AN ELEVATED SEVERE THREAT
CONSIDERING THE FAVORABLE CAPE AND EXPECTATION OF EFFECTIVE SHEER
INCREASING LATER THIS AFTERNOON/EVENING AS TROUGH MOVES INTO THE
REGION. PROFILES WOULD ALSO SUPPORT POTENTIAL FOR MICROBURST
POTENTIAL...WHICH IS ALSO SUPPORTED BY DCAPE VALUES AROUND 1800
J/KG. AS SHORTWAVE TROUGH SHIFTS EAST A WEAK FRONTAL PASSAGE WILL
SLIGHTLY COOL TEMPS ALOFT TONIGHT AND PRECIP SHOULD COME TO AN END
ACROSS THE EAST AFTER MIDNIGHT.
MONDAY...WITH ELEVATED FRONT ACROSS THE NORTH...AND WASHED OUT
FRONT/SURFACE BAROCLINIC ZONE IN THE SOUTH THUNDERSTORM
REDEVELOPMENT WILL BE POSSIBLE ACROSS THE CWA MONDAY AFTERNOON.
ANOTHER WEAK VORTICITY MAX WILL ROTATE JUST NORTH OF THE CWA
MONDAY AFTERNOON/EVENING...WHICH COULD ALSO HELP WITH THUNDERSTORM
INITIATION. PRECIP SIGNAL IS STRONGEST ACROSS THE SOUTHERN CWA
THROUGH MONDAY AFTERNOON ALONG BAROCLINIC ZONE AS IS LIFTS
NORTH...WITH BETTER COVERAGE TOWARDS LATE AFTERNOON IN THE SOUTH.
HIGH TEMPS MONDAY SHOULD BE SLIGHTLY COOLER THAN TODAY...THOUGH
THEY WILL REMAIN ABOVE NORMAL WITH MOST LOCATIONS IN THE LOW-MID
90S.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 227 PM MDT SUN AUG 17 2014
SHOWER/THUNDERSTORM ACTIVITY SHOULD CONTINUE ACROSS THE REGION
MONDAY EVENING BEFORE COMING TO AN END EARLY TUESDAY MORNING. AT
FIRST...MAIN ACTIVITY SHOULD MOVE IN FROM NORTH CENTRAL COLORADO
UNDER WEST-NORTHWEST FLOW. GFS CONDENSATION PRESSURE DEFICITS AND
WINDS AT 320K INDICATE THAT ADDITIONAL ELEVATED STORM DEVELOPMENT IS
POSSIBLE BY MIDNIGHT AS MAIN SHORTWAVE TROUGH PASSES THROUGH.
DECIDED TO KEEP CHANCE POPS GOING THROUGH MOST OF THE NIGHT BEFORE
WANING EARLY TUESDAY MORNING...BETWEEN 3-6 AM MDT. SOME OF THESE
STORMS COULD BECOME SEVERE WITH LARGE HAIL AND DAMAGING WINDS AS THE
MAIN THREAT...TRANSITIONING TO PRIMARILY A LARGE HAIL THREAT WITH
THE OVERNIGHT ELEVATED THUNDERSTORM ACTIVITY.
THROUGH THE REST OF THE EXTENDED FORECAST PERIOD...A PERSISTENT
UPPER LEVEL PATTERN IS THE MAIN STORY BEFORE A PACIFIC NORTHWEST
TROUGH BREAKS THE RIDGE DOWN TOWARDS NEXT WEEKEND. FOR EACH DAY...
SHOWERS AND STORMS ARE POSSIBLE AS WEAK UPPER LEVEL DISTURBANCES
PASS OVER THE NORTHERN PERIPHERY OF THE SOUTHWESTERN U.S. RIDGE.
STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE TUESDAY WITH CAPE OF
2000-2500J/KG ALONG AND NORTH OF INTERSTATE 70...850-500 MB LAPSE
RATES AROUND 8 C/KM AND 0-6 KM BULK SHEAR AROUND 30-35 KTS. SOME
DRIER BOUNDARY LAYER AIR MOVES INTO THE REGION FROM THE WEST FOR
WEDNESDAY AND THURSDAY...LIMITING SEVERE CHANCES SOME BY DECREASING
AVAILABLE MOISTURE AND ATMOSPHERIC INSTABILITY.
AS FOR TEMPERATURES...HOT WEATHER IS EXPECTED TO PERSIST UNTIL THE
RIDGE BEGINS TO BREAK DOWN NEXT WEEKEND. DID LOWER MIN TEMPERATURES
A TOUCH BELOW MODEL GUIDANCE BASED ON RECENT TRENDS OBSERVED AND
COOL THUNDERSTORM OUTFLOWS LIKELY EACH EVENING. MODEL GUIDANCE...
ESPECIALLY THE EUROPEAN...SUGGESTS THAT A COLD FRONT PASSAGE IS
POSSIBLE BY THE END OF THE WEEK. MODEL AGREEMENT IS FAIRLY POOR WITH
THE GFS SUGGESTING THE HOT WEATHER WILL REMAIN. THEREFORE...DID NOT
MAKE ANY LARGE CHANGES TO THE EXTENDED FORECAST.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1047 PM MDT SUN AUG 17 2014
VFR CONDITIONS WILL CONTINUE OVERNIGHT AT KGLD AND KMCK. BOUNDARY
LAYER RH WILL STAY LOW ENOUGH TO LIMIT ANY STRATUS OR FOG IN THE
MCK AND KGLD AREAS LATE TONIGHT/EARLY MONDAY MORNING. THERE WILL
BE ANOTHER CHANCE OF THUNDERSTORMS MONDAY AFTERNOON AND EVENING.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...RRH
AVIATION...FS
AREA FORECAST DISCUSSION
NWS JACKSON KY
702 PM EDT MON AUG 18 2014
.UPDATE...
ISSUED AT 702 PM EDT MON AUG 18 2014
UPDATED THE FORECAST TO BETTER REFLECT CURRENT CONDITIONS AND MODEL
TRENDS. THE PRECIPITATION HAS BEEN TAPERING OFF AS THE SHORT WAVE
MOVES OFF TO THE EAST. LOWERED THE PROBABILITY OF PRECIPITATION
BASED ON CURRENT RADAR AND THE LATEST HRRR OUTPUT. ALSO TOOK OUT THE
CHANCE OF THUNDER OUT AS NONE HAS DEVELOPED ALL DAY AND THE MODELS
ARE NOT SUPPORTING THEIR DEVELOPMENT IN THE NEAR TERM. THE ONLY
THUNDER IS CURRENTLY OVER CENTRAL TENNESSEE. A WEAK FRONT IS STILL
QUASI STATIONARY OVER THE AREA. EXPECT TO SEE SOME FAIRLY DENSE FOG
TONIGHT...ESPECIALLY IN THE VALLEYS.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 255 PM EDT MON AUG 18 2014
THE LOW PRESSURE SYSTEM THAT BROUGHT THE WIDESPREAD RAIN LAST NIGHT
INTO THIS MORNING HAS MOVED INTO WV...TAKING THE DEEPER MOISTURE AND
BETTER LIFT WITH IT. A WEST EAST ORIENTED QUASI STATIONARY FRONT
REMAINS ACROSS KENTUCKY...AND SCATTERED LIGHT SHOWERS CONTINUE TO
MOVE FROM WEST TO EAST ACROSS THE AREA. ANOTHER WAVE OF LOW PRESSURE
EVIDENT ON SATELLITE AND RADAR IMAGERY WAS MOVING EAST ALONG THE TN MS
BORDER. THIS FEATURE...ALONG WITH THE BOUNDARY ACROSS KY WILL
NECESSITATE CONTINUING WITH A CHANCE OF RAIN OVERNIGHT. HOWEVER THE
BEST RAIN AND THUNDER CHANCES SHOULD BE SOUTH OF KY TONIGHT.
WITH VERY MOIST BOUNDARY LAYER AND SOME BREAKS EXPECTED IN THE CLOUDS
THIS EVENING...FOG AND LOW CLOUDS ARE EXPECTED TO DEVELOP DURING THE
NIGHT AND LINGER INTO THE MORNING ON TUESDAY. WILL INCLUDE FOG IN THE
FORECAST FOR TONIGHT. ON TUESDAY THE NEXT SHORT WAVE IN THIS VERY
ACTIVE PATTERN WILL BE PUSHING INTO THE WESTERN GREAT LAKES REGION. AT
THE SURFACE A VERY MOIST AND WARM AIR MASS WILL REMAIN IN PLACE
ACROSS EASTERN KY ON TUESDAY...WHILE A COLD FRONT DROPS SOUTHEAST ACROSS IL
AND INDIANA. THUNDERSTORMS ARE EXPECTED TO DEVELOP AHEAD OF THIS
FRONT TUESDAY AFTERNOON. CURRENT THINKING IS THAT SHOWERS AND
THUNDERSTORMS THAT DEVELOP TO OUR NORTHWEST ON TUESDAY WILL MOVE INTO
OUR AREA TUESDAY NIGHT. WITH THIS THOUGHT IN MIND WILL INTRODUCE
LIKELY PROBABILITIES FOR SHOWERS AND THUNDERSTORMS IN THE NORTHERN
PART OF OUR FORECAST AREA TUESDAY NIGHT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 255 PM EDT MON AUG 18 2014
MODELS CONTINUE TO DISPLAY GOOD AGREEMENT THROUGH THE EXTENDED.
UPPER/MID LEVEL GREAT LAKES LOW WILL MAKE A BEE LINE TO THE MID
ATLANTIC COAST BY FRIDAY. MEANWHILE BURGEONING RIDGE TO OUR WEST
WILL EXERT ITS INFLUENCE FROM THE SOUTHERN PLAINS/MISSISSIPPI RIVER
DELTA NORTHWARD INTO THE UPPER MIDWEST. GREAT LAKES LOW WILL PASS TO
OUR NORTHEAST DURING ITS MARCH TO THE COAST AND DRAG A SURFACE
FRONTAL BOUNDARY ACROSS THE CENTER OF THE OHIO VALLEY REGION.
SHARPENING UPPER LEVEL RIDGE AXIS WILL SHIFT SOUTHEASTWARD OVER OUR
AREA TOWARDS THE END OF THE EXTENDED AS ENERGY ROUNDS ITS TOP ACROSS
THE NORTHERN TIER. DESPITE THE BUILDING RIDGE ALOFT...THE BY THEN
QUASI-STATIONARY SFC FRONTAL BOUNDARY WILL REMAIN IN OUR VICINITY AS
IT BECOMES ORIENTED PARALLEL TO THE UPPER LEVEL FLOW PATTERN. THUS
WITH LITTLE TO NO FORCING AT THE MID AND UPPER LEVELS...THIS
BOUNDARY WILL REMAIN CLOSE ENOUGH TO OUR AREA TO SERVE AS A FOCUS
FOR ADDITIONAL SHOWER AND THUNDERSTORM ACTIVITY THROUGH THE LATTER
HALF OF THE EXTENDED PERIOD. THE MAINLY DIURNAL SHOWER AND
THUNDERSTORM ACTIVITY MAY BE AUGMENTED BY ONE OR TWO ORGANIZED
THUNDERSTORM COMPLEXES DROPPING DOWN FROM THE NORTHWEST ON THE EAST
SIDE OF THE UPPER RIDGE.
FOR SENSIBLE WEATHER...WE WILL SEE THE RETURN OF TRUE SUMMER LIKE
WEATHER AS RIDGING TO OUR SOUTHWEST WILL BE STRONG ENOUGH TO SEND
TEMPERATURES INTO AND ABOVE SEASONABLE NORMS DESPITE THE INCREASED
HUMIDITY. THIS WILL ALSO HELP TO ENHANCE THE DIURNALLY DRIVEN
INSTABILITY ACROSS THE AREA RESULTING IN THE BEST CHANCES OF STORMS
EACH AFTERNOON AND EVENING. THE THREAT OF RAIN DECREASES BY NEXT
WEEKEND AS THE UPPER RIDGE AMPLIFIES AND SHIFTS EASTWARD A BIT...BUT
THE POTENTIAL CAN NOT BE TOTALLY REMOVED. IN ADDITION...SHOULD THE
RIDGE EXERT A STRONGER INFLUENCE BY SHIFTING JUST A BIT MORE EAST WE
MAY BE IN FOR EVEN HOTTER WEATHER BY NEXT WEEKEND. WITH THE 0Z ECMWF
ADVERTISING H850 TEMPS UP AROUND 22C TO 24C...THE POSSIBLY EXISTS
THAT WE MIGHT SEE SOME OF OUR HOTTEST WEATHER OF THE SUMMER THUS
FAR.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 702 PM EDT MON AUG 18 2014
A WIDE VARIETY OF CONDITIONS CAN BE EXPECTED ACROSS EASTERN KENTUCKY
FOR THE REMAINDER OF THE EARLY EVENING. AS THERE IS SOME CLEARING
THIS EVENING...EXPECT TO SEE SOME DENSE FOG FORMING IN THE VALLEYS
AS WELL AS THE TAF STATIONS WITH VLIFR AND IFR CONDITIONS
PREDOMINATING. THE FOG WILL MOST LIKELY TAKE UNTIL 14-15Z TO FINALLY
BURN OFF. EXPECTING SOME SCATTERED SHOWERS AND THUNDERSTORMS TOMORROW
ACROSS THE AREA. EXPECT THE ACTIVITY TO PICK UP IN THE LATE AFTERNOON
AND EVENING. WILL MOST LIKELY NOT SEE MUCH VFR TOMORROW UNTIL THE
AFTERNOON.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JJ
SHORT TERM...SBH
LONG TERM...RAY
AVIATION...JJ
AREA FORECAST DISCUSSION
NWS JACKSON KY
129 AM EDT MON AUG 18 2014
.UPDATE...
ISSUED AT 125 AM EDT MON AUG 18 2014
CURRENT CONDITIONS ACROSS THE AREA FEATURE SOME SHOWERS ALONG WITH
SOME ISOLATED THUNDERSTORMS MOVING INTO THE AREA IN THE SOUTHWEST AS
WELL AS SOME ISOLATED POP UP SHOWERS OVER THE EAST AND NORTHEAST.
THIS WILL CONTINUE AS THE PARENT LOW AND ASSOCIATED BETTER LIFT ENTER
EASTERN KENTUCKY INTO THE REST OF THE OVERNIGHT AND INTO THE DAWN
HOURS. NO CHANGE TO THE ZFP IS EXPECTED AS CURRENT POP FORECAST LOOKS
TO BE ON TRACK WITH MINOR CHANGES. EVERYTHING ELSE LOOKS TO BE ON
TRACK. THE CONCERN WITH THE FLASH FLOODING STILL LOOKS TO MINOR AND
RATHER LOCALIZED SO WILL CONTINUE HIGHLIGHTING THOSE ISSUES AS HAS THE
DAY SHIFT WITH THE HWO.
UPDATE ISSUED AT 1035 PM EDT SUN AUG 17 2014
UPDATED THE FORECAST TO BETTER REFLECT CURRENTS CONDITIONS AND MODEL
TRENDS. THE ISOLATED ACTIVITY CURRENTLY OVER THE AREA WILL BE
INCREASING AS THE TROUGH APPROACHES FROM THE WEST. SO FAR
PRECIPITATION AMOUNTS OVER CENTRAL KENTUCKY HAVE CONFIRMED THAT A
FLASH FLOOD WATCH IS NOT NEEDED. ALSO THE HRRR AND NEW NAM WOULD ALSO
BE SUPPORTIVE ON NOT ISSUING A FLASH FLOOD WATCH AT THIS TIME. THE
REST OF THE FORECAST IS ON TRACK.
UPDATE ISSUED AT 905 EDT SUN AUG 17 2014
UPDATED THE FORECAST TO BETTER REFLECT CURRENT CONDITIONS AND MODEL
TRENDS. SOME ISOLATED TO SCATTERED SHOWERS ARE CURRENTLY MOVING
ACROSS THE AREA WITH THE HEAVIER PRECIPITATION OVER CENTRAL KENTUCKY.
THIS HEAVIER AREA WILL BE MOVING INTO THE AREA AFTER 11 PM TONIGHT.
LOOKING AT THE MODELS AND THE RAINFALL AMOUNTS UPSTREAM...THE CONCERN
FOR LOCALIZED FLOODING IS A LITTLE LOWER THAN EARLIER THINKING. THERE
STILL COULD BE SOME VERY LOCALIZED ISSUES WILL SOME CREEKS...DITCHES
AND LOW WATER CROSSING RUNNING FULL DURING THE OVERNIGHT AND MORNING
HOURS. THE REST OF THE FORECAST IS ON TRACK.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 303 PM EDT SUN AUG 17 2014
MAIN HEAVY RAIN THREAT WILL BE FROM THIS EVENING INTO MONDAY
MORNING. WIDESPREAD 1 INCH RAINFALL AMOUNTS ARE FORECAST TONIGHT INTO
MONDAY WITH ISOLATED SPOTS RECEIVING IN EXCESS OF 2 INCHES. BASED ON
CURRENT RADAR TRENDS AND EXPECTED DEVELOPMENT THIS EVENING THE
HEAVIEST RAINS WILL LIKELY FALL JUST SOUTH OF KY OVER TN.
LOW PRESSURE OVER SOUTHWEST INDIANA AT SURFACE AND ALOFT WILL TRACK
SLOWLY EAST ACROSS KY TONIGHT...BUT IS NOT EXPECTED TO MOVE EAST OF
OUR AREA UNTIL BETWEEN 12Z AND 18Z MONDAY. AS THE LOW MOVES EAST THE 8H
JET WILL RAMP UP AND LIFT WILL INCREASE LATER TONIGHT. MODELS ARE IN
GOOD AGREEMENT WITH PWS FORECAST AROUND 2 INCHES. THIS IDEA IS
SUPPORTED BY GOES SOUNDER DATA THAT WAS AVAILABLE PRIOR TO THE
WIDESPREAD CLOUD COVER. AFTER COORDINATION WITH NEIGHBORING FORECAST
OFFICES WILL NOT BE ISSUING A FLASH FLOOD WATCH AT THIS TIME...BUT
THE SITUATION WILL NEED TO BE MONITORED CLOSELY TONIGHT INTO MONDAY
MORNING. CONVECTION WILL BE LESS ORGANIZED AFTER THE LOW MOVES
EAST OF OUR AREA ON MONDAY...BUT A CHANCE OF SHOWERS AND THUNDERSTORMS
WILL LINGER INTO MONDAY NIGHT ESPECIALLY IN THE EAST.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 303 PM EDT SUN AUG 17 2014
MEDIUM RANGE MODELS POINT TO A RETURN TO A MORE TYPICAL SUMMER-LIKE
PATTERN FOR THE SOUTHERN AND CENTRAL APPALACHIANS AS A RIDGE OF HIGH
PRESSURE BUILDS EASTWARD FROM THE SOUTHERN PLAINS IN THE SOUTHEAST
CONUS. HERE AT NWS JACKSON...OUR DAILY AVERAGE TEMPERATURE HAS BEEN
NORMAL OR BELOW EVERY DAY SINCE JULY 23RD. THAT TREND WILL LIKELY
END BY MID WEEK AS TEMPERATURES MODERATE TO SLIGHTLY ABOVE NORMAL
LEVELS. DEWPOINTS AROUND 70 WILL MAKE IT FEEL LIKE SUMMER FOR SURE.
DESPITE THE BUILDING RIDGE ALOFT...A QUASI-STATIONARY FRONTAL
BOUNDARY...A WEAKENED FEATURE LEFTOVER FROM THE SHORT TERM
PERIOD...WILL REMAIN IN OUR VICINITY PRETTY MUCH THROUGHOUT THE LONG
TERM PERIOD. THIS FRONT WILL WAFFLE NORTH AND SOUTH BUT LIKELY
REMAIN CLOSE ENOUGH TO BE A FOCUS FOR DAILY SHOWER AND THUNDERSTORM
CHANCES WITH THE WARM AND UNSTABLE AIRMASS IN PLACE. THIS SHOULD BE
TYPICAL SCATTERED ACTIVITY WITH GREATEST COVERAGE DURING THE
AFTERNOON AND EARLY EVENING HOURS...BUT MAY POTENTIALLY BE AUGMENTED
BY ONE OR TWO ORGANIZED THUNDERSTORM COMPLEXES DROPPING DOWN FROM
THE NORTHWEST ON THE NORTHEAST SIDE OF THE BUILDING UPPER RIDGE.
STORM CHANCES DECREASE SLIGHTLY NEXT WEEKEND AS THE UPPER RIDGE
AMPLIFIES A BIT...BUT CANNOT BE TOTALLY REMOVED.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 125 AM EDT MON AUG 18 2014
SHOWERS AND A FEW THUNDERSTORMS WILL CONTINUE TO ENTER EASTERN
KENTUCKY THROUGH THE EARLY MORNING HOURS. THIS WILL EVENTUALLY BRING
VISIBILITY AND CEILINGS DOWN TO FIELD MINS EVENTUALLY...MAINLY THOUGH
WHERE HEAVIER SHOWERS MOVE OVER A POINT. WILL EXPECT TO KEEP THESE
CONDITIONS THROUGH THE MORNING BEFORE LIFTING THE CEILINGS INTO THE
AFTERNOON AS THE MAIN LIFT AND MOISTURE FINALLY MOVE OFF TO THE EAST.
EXPECT MOST OF THE TAF SITES TO EXPERIENCE BELOW IFR IN 08Z TO 14Z
PERIOD. WINDS WILL MAINLY BE LIGHT THROUGH THE MORNING BUT THEN
PICKING UP OUR OF THE WEST INTO THE AFTERNOON WITH THE PASSAGE OF THE
SURFACE FRONT.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SHALLENBERGER
SHORT TERM...SBH
LONG TERM...ABE
AVIATION...SHALLENBERGER
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
1248 PM CDT MON AUG 18 2014
.AVIATION...
FOR THE 18/18Z TAFS...EARLIER ROUND OF CONVECTION HAS EXITED THE
AREA BUT A FEW SCT SHWRS CONTINUE TO DEVELOP ALONG A SHEAR AXIS
ORIENTED ROUGHLY ALONG THE I-20 CORRIDOR. COVERAGE IS SPOTTY BUT
WILL MAINTAIN VCSH AT THE I-20 TERMINALS UNTIL EARLY THIS EVENING
WHEN THE SHWRS ARE EXPECTED TO DISSIPATE. LOW CLOUDS AND FOG
SHOULD DEVELOP ACROSS MOST OF THE AREA AFTER 19/08Z WITH
CONDITIONS GRADUALLY IMPROVING BY MID MORNING TUESDAY. /09/
&&
.PREV DISCUSSION... /ISSUED 1145 AM CDT MON AUG 18 2014/
DISCUSSION...
LATE THIS MORNING THE UPPER LEVEL DISTURBANCE HAS SHIFTED EAST INTO
EASTERN ARKANSAS AND ALONG THE MISSISSIPPI RIVER AND CONTINUED TO
PRODUCE SHOWERS AND THUNDERSTORMS OVER PARTS OF ARKANSAS AND
NORTHEAST LOUISIANA. THE UPPER LEVEL SHEAR AXIS THAT HAS BEEN OVER
THE FOUR STATE REGION FOR THE PAST FEW DAYS HAS SHIFTED TO THE
SOUTH AND EXTENDED ACROSS PARTS OF CENTRAL MISSISSIPPI AND ACROSS
LOWER PARTS OF NORTHWEST AND NORTH CENTRAL LOUISIANA AND EAST TEXAS.
THIS AREA AND SOUTH WILL BE WHERE EXPECTED RAIN CHANCES WILL BE LATER
THE REST OF TODAY. ANOTHER UPPER DISTURBANCE WAS MOVING ACROSS NORTHEAST
OKLAHOMA...AND WAS PRODUCING SHOWERS AND THUNDERSTORMS. THE SYSTEM
WILL MOVE INTO WESTERN ARKANSAS AND MAY AFFECT PARTS OF SOUTHWEST AND
SOUTH CENTRAL ARKANSAS LATER THIS AFTERNOON AND OVERNIGHT. MADE
ADJUSTMENT IN THE RAIN CHANCES FOR TODAY AND TONIGHT BASED ON THE
CURRENT TRENDS AND FORECAST TRACK AND LOCATIONS OF THE UPPER SYSTEMS.
/06/
PREV DISCUSSION... /ISSUED 443 AM CDT MON AUG 18 2014/
DISCUSSION...
CONVECTION OVER SW AR HAS RAPIDLY DEVELOPED ON THE ERN PERIPHERY
OF AN MCV...WHERE RADAR AND SATELLITE INDICATE TO BE CENTERED NEAR
DEQ AS OF 09Z. LOCALLY HEAVY RAINFALL HAS BEEN EVIDENT PER
REFLECTIVITY IMAGERY...WHERE PERSISTENT TRAINING OF CONVECTION HAS
RESULTED IN WIDESPREAD 2-4 INCH RAINFALL TOTALS...PER DUAL POL
ESTIMATES. THE 00Z WRF HAS AGAIN INITIALIZED WELL THIS
MORNING WITH THE POSITION AND SLOWER MOVEMENT OF THE MCV...WITH THE
GFS CONTINUING TO SUFFER FROM FEEDBACK PROBLEMS AND SHOWS A MUCH
MORE RAPID PROGRESSION OF THE MCV ACROSS SW AR /EXITING THE AREA SHORTLY
AFTER 12Z/. MEANWHILE...THE LATEST HRRR IS OUT TO LUNCH AND DOES
NOT EVEN ACKNOWLEDGE THE CURRENT CONVECTION BUT DOES SUGGEST SCT
DEVELOPMENT LATER THIS MORNING CONTINUING THROUGH THE AFTERNOON
NEAR THE PARENT UPPER SHEAR AXIS OVER EXTREME NRN LA. THE CURRENT
HEAVY RAINFALL AXIS LINES UP WELL WITH A TONGUE OF GREATER SFC
THETA-E AND SBCAPES...WHICH RANGE FROM 1000-1500 J/KG AS OF 09Z.
THIS SHOULD CONTINUE TO FAVOR A SHORT TERM HEAVY RAINFALL THREAT
THIS MORNING OVER SW AR...AS THE MCV DRIFTS SLOWLY E THIS MORNING.
HAVE SEEN SCT CONVECTION DEVELOP FARTHER S ACROSS NRN
CADDO/BOSSIER/WEBSTER PARISHES AS WELL BENEATH THE MCV WHERE
850-700MB THETA-E RIDGING SHOULD RESULT IN CONVECTION EXPANDING E
ALONG/N OF THE I-20 CORRIDOR THROUGH MIDDAY. GIVEN THESE
OBSERVATIONS AND THE FACT THAT PW/S SHOULD RANGE FROM 2-2.25
INCHES...HAVE INCREASED POPS TO LIKELY THIS MORNING AND ADDED
HEAVY RAINFALL WORDING ACROSS MUCH OF SW AR...AND HAVE MAINTAINED
MID TO HIGH CHANCE POPS FARTHER S ACROSS NCNTRL LA AS THE MCV
SHIFTS E TO THE MS RIVER BY MIDDAY...AND ITS ATTENDANT SHEAR AXIS
DRIFTS ESE ACROSS THE AREA. THE AFTERNOON SEABREEZE SHOULD BE LESS
OF A FACTOR THIS AFTERNOON OVER DEEP E TX AS 850MB WINDS REMAIN
WSW BENEATH THE SHEAR AXIS...THUS SLIGHT CHANCE POPS SHOULD
SUFFICE FOR THESE AREAS. MAX TEMPS TODAY WILL AGAIN BE A TOUGH
CALL...BUT HAVE LOWERED TEMPS SLIGHTLY TO NEAR 90S OVER SCNTRL
AR/NCNTRL LA...WITH MID 90S EXPECTED ELSEWHERE AS THE AC CANOPY
BENEATH THE MCV GRADUALLY ERODES AND GIVES WAY TO SUNSHINE THIS
AFTERNOON.
THE WRF DOES SUGGEST A WEAK REFLECTION OF THE SHEAR AXIS REMAINING
IN PLACE ACROSS N LA/DEEP E TX THIS EVENING...AND THUS HAVE
MAINTAINED SLIGHT CHANCE POPS FOR THESE AREAS. AFTERWARDS...FLAT
500MB RIDGING IS EXPECTED TO SHIFT E INTO THE SRN PLAINS TUESDAY
FROM THE SRN ROCKIES...WITH A WEAK SEABREEZE POSSIBLE ACROSS DEEP
E TX/SRN SECTIONS OF NCNTRL LA DURING THE AFTERNOON AND EARLY
EVENING. UPPER RIDGING OVER THE WRN ATLANTIC AND ERN GULF REMAINS
PROGGED TO EXPAND FARTHER WNW WHILE ABSORBING THE 500MB RIDGE
CENTER OVER THE LOWER MS VALLEY WEDNESDAY...BEFORE CENTERING
ITSELF OVER THE MID-SOUTH REGION/LOWER MS VALLEY THURSDAY. STILL
SHOULD SEE A COUPLE MORE DAYS OF WEAK SEABREEZE CONVECTION ACROSS
OUR SRN ZONES WEDNESDAY AND THURSDAY...BEFORE LARGE SCALE
SUBSIDENCE BENEATH THE RIDGE INCREASES AS THE RIDGE CENTER BECOMES
POSITIONED OVER THE REGION.
PERSISTENCE WILL DOMINATE LATE THIS WEEK THROUGH THE REMAINDER OF
THE EXTENDED...WITH MAX TEMPS IN THE MID/UPPER 90S EACH DAY. STILL
CAN/T RULE OUT TRIPLE DIGIT HEAT OCCURRING LATE THIS WEEK THROUGH
EARLY NEXT WEEKEND ESPECIALLY OVER E TX/PORTIONS OF NW LA...WHICH
HAVE BEEN MOSTLY VOID OF WETTING RAINFALL THE LAST FEW WEEKS AND
WILL APPEAR TO MISS MUCH OF THE CONVECTION THIS MORNING. BOTH THE
GFS/ECMWF DO SUGGEST THAT THE RIDGE CENTER MAY SHIFT A TAD FARTHER
E INTO THE SE STATES BY MIDWEEK NEXT WEEK...ALLOWING WEAKNESSES
BENEATH THE RIDGE TO RETROGRADE W AND POSSIBLY ALLOW FOR ISOLATED
CONVECTION OVER THE SRN ZONES AS WE ENTER THE FINAL FEW DAYS OF
AUGUST.
PRELIMS TO FOLLOW BELOW...
15
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 75 96 75 96 75 / 10 10 10 10 10
MLU 74 95 74 95 74 / 20 10 10 10 10
DEQ 71 95 72 95 73 / 0 10 0 0 0
TXK 74 95 74 96 74 / 10 10 0 0 0
ELD 73 95 73 96 74 / 20 10 0 0 0
TYR 75 96 75 96 75 / 10 10 10 10 10
GGG 74 96 74 96 75 / 10 10 10 10 10
LFK 76 97 76 96 76 / 20 20 10 20 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
09
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
1145 AM CDT MON AUG 18 2014
.DISCUSSION...
LATE THIS MORNING THE UPPER LEVEL DISTURBANCE HAS SHIFTED EAST INTO
EASTERN ARKANSAS AND ALONG THE MISSISSIPPI RIVER AND CONTINUED TO
PRODUCE SHOWERS AND THUNDERSTORMS OVER PARTS OF ARKANSAS AND
NORTHEAST LOUISIANA. THE UPPER LEVEL SHEAR AXIS THAT HAS BEEN OVER
THE FOUR STATE REGION FOR THE PAST FEW DAYS HAS SHIFTED TO THE
SOUTH AND EXTENDED ACROSS PARTS OF CENTRAL MISSISSIPPI AND ACROSS
LOWER PARTS OF NORTHWEST AND NORTH CENTRAL LOUISIANA AND EAST TEXAS.
THIS AREA AND SOUTH WILL BE WHERE EXPECTED RAIN CHANCES WILL BE LATER
THE REST OF TODAY. ANOTHER UPPER DISTURBANCE WAS MOVING ACROSS NORTHEAST
OKLAHOMA...AND WAS PRODUCING SHOWERS AND THUNDERSTORMS. THE SYSTEM
WILL MOVE INTO WESTERN ARKANSAS AND MAY AFFECT PARTS OF SOUTHWEST AND
SOUTH CENTRAL ARKANSAS LATER THIS AFTERNOON AND OVERNIGHT. MADE
ADJUSTMENT IN THE RAIN CHANCES FOR TODAY AND TONIGHT BASED ON THE
CURRENT TRENDS AND FORECAST TRACK AND LOCATIONS OF THE UPPER SYSTEMS.
/06/
&&
.PREV DISCUSSION... /ISSUED 529 AM CDT MON AUG 18 2014/
AVIATION...
CLUSTER OF INTENSE TSTMS SLOWLY SHIFTING EAST ACROSS SW AR...MOVG
EAST OF KTXK TERMINAL...BUT NOW MOVG INTO KELD TERMINAL. STEEP
LAPSE RATES KEEPING MOST CLOUD BASES IN VFR...EVEN NEAR STORMS.
OUTFLOW BOUNDARIES MAY REGENERATE MIDDAY STORMS OVER KMLU AND
POSSIBLY KSHV TERMINALS...LESS CONVECTIVE ACTIVITY OVER NE TX EXPECTED.
HOWEVER...MID LVL DECKS WITH LGT RAIN MOVG EAST TOWARDS KTYR AND
KGGG. SW WINDS NEAR 10 KTS ACROSS MUCH OF AREA...MAINLY BTWN 18/15-21Z
TODAY...EXCEPT POSSIBLE GUSTS NEAR CONVECTION. ALSO...PATCHY FOG
POSSIBLE OVERNIGHT...MAINLY WHERE HEAVY RAIN FELL AT KTXK AND
KELD./VII/.
PREV DISCUSSION... /ISSUED 443 AM CDT MON AUG 18 2014/
DISCUSSION...
CONVECTION OVER SW AR HAS RAPIDLY DEVELOPED ON THE ERN PERIPHERY
OF AN MCV...WHERE RADAR AND SATELLITE INDICATE TO BE CENTERED NEAR
DEQ AS OF 09Z. LOCALLY HEAVY RAINFALL HAS BEEN EVIDENT PER
REFLECTIVITY IMAGERY...WHERE PERSISTENT TRAINING OF CONVECTION HAS
RESULTED IN WIDESPREAD 2-4 INCH RAINFALL TOTALS...PER DUAL POL
ESTIMATES. THE 00Z WRF HAS AGAIN INITIALIZED WELL THIS
MORNING WITH THE POSITION AND SLOWER MOVEMENT OF THE MCV...WITH THE
GFS CONTINUING TO SUFFER FROM FEEDBACK PROBLEMS AND SHOWS A MUCH
MORE RAPID PROGRESSION OF THE MCV ACROSS SW AR /EXITING THE AREA SHORTLY
AFTER 12Z/. MEANWHILE...THE LATEST HRRR IS OUT TO LUNCH AND DOES
NOT EVEN ACKNOWLEDGE THE CURRENT CONVECTION BUT DOES SUGGEST SCT
DEVELOPMENT LATER THIS MORNING CONTINUING THROUGH THE AFTERNOON
NEAR THE PARENT UPPER SHEAR AXIS OVER EXTREME NRN LA. THE CURRENT
HEAVY RAINFALL AXIS LINES UP WELL WITH A TONGUE OF GREATER SFC
THETA-E AND SBCAPES...WHICH RANGE FROM 1000-1500 J/KG AS OF 09Z.
THIS SHOULD CONTINUE TO FAVOR A SHORT TERM HEAVY RAINFALL THREAT
THIS MORNING OVER SW AR...AS THE MCV DRIFTS SLOWLY E THIS MORNING.
HAVE SEEN SCT CONVECTION DEVELOP FARTHER S ACROSS NRN
CADDO/BOSSIER/WEBSTER PARISHES AS WELL BENEATH THE MCV WHERE
850-700MB THETA-E RIDGING SHOULD RESULT IN CONVECTION EXPANDING E
ALONG/N OF THE I-20 CORRIDOR THROUGH MIDDAY. GIVEN THESE
OBSERVATIONS AND THE FACT THAT PW/S SHOULD RANGE FROM 2-2.25
INCHES...HAVE INCREASED POPS TO LIKELY THIS MORNING AND ADDED
HEAVY RAINFALL WORDING ACROSS MUCH OF SW AR...AND HAVE MAINTAINED
MID TO HIGH CHANCE POPS FARTHER S ACROSS NCNTRL LA AS THE MCV
SHIFTS E TO THE MS RIVER BY MIDDAY...AND ITS ATTENDANT SHEAR AXIS
DRIFTS ESE ACROSS THE AREA. THE AFTERNOON SEABREEZE SHOULD BE LESS
OF A FACTOR THIS AFTERNOON OVER DEEP E TX AS 850MB WINDS REMAIN
WSW BENEATH THE SHEAR AXIS...THUS SLIGHT CHANCE POPS SHOULD
SUFFICE FOR THESE AREAS. MAX TEMPS TODAY WILL AGAIN BE A TOUGH
CALL...BUT HAVE LOWERED TEMPS SLIGHTLY TO NEAR 90S OVER SCNTRL
AR/NCNTRL LA...WITH MID 90S EXPECTED ELSEWHERE AS THE AC CANOPY
BENEATH THE MCV GRADUALLY ERODES AND GIVES WAY TO SUNSHINE THIS
AFTERNOON.
THE WRF DOES SUGGEST A WEAK REFLECTION OF THE SHEAR AXIS REMAINING
IN PLACE ACROSS N LA/DEEP E TX THIS EVENING...AND THUS HAVE
MAINTAINED SLIGHT CHANCE POPS FOR THESE AREAS. AFTERWARDS...FLAT
500MB RIDGING IS EXPECTED TO SHIFT E INTO THE SRN PLAINS TUESDAY
FROM THE SRN ROCKIES...WITH A WEAK SEABREEZE POSSIBLE ACROSS DEEP
E TX/SRN SECTIONS OF NCNTRL LA DURING THE AFTERNOON AND EARLY
EVENING. UPPER RIDGING OVER THE WRN ATLANTIC AND ERN GULF REMAINS
PROGGED TO EXPAND FARTHER WNW WHILE ABSORBING THE 500MB RIDGE
CENTER OVER THE LOWER MS VALLEY WEDNESDAY...BEFORE CENTERING
ITSELF OVER THE MID-SOUTH REGION/LOWER MS VALLEY THURSDAY. STILL
SHOULD SEE A COUPLE MORE DAYS OF WEAK SEABREEZE CONVECTION ACROSS
OUR SRN ZONES WEDNESDAY AND THURSDAY...BEFORE LARGE SCALE
SUBSIDENCE BENEATH THE RIDGE INCREASES AS THE RIDGE CENTER BECOMES
POSITIONED OVER THE REGION.
PERSISTENCE WILL DOMINATE LATE THIS WEEK THROUGH THE REMAINDER OF
THE EXTENDED...WITH MAX TEMPS IN THE MID/UPPER 90S EACH DAY. STILL
CAN/T RULE OUT TRIPLE DIGIT HEAT OCCURRING LATE THIS WEEK THROUGH
EARLY NEXT WEEKEND ESPECIALLY OVER E TX/PORTIONS OF NW LA...WHICH
HAVE BEEN MOSTLY VOID OF WETTING RAINFALL THE LAST FEW WEEKS AND
WILL APPEAR TO MISS MUCH OF THE CONVECTION THIS MORNING. BOTH THE
GFS/ECMWF DO SUGGEST THAT THE RIDGE CENTER MAY SHIFT A TAD FARTHER
E INTO THE SE STATES BY MIDWEEK NEXT WEEK...ALLOWING WEAKNESSES
BENEATH THE RIDGE TO RETROGRADE W AND POSSIBLY ALLOW FOR ISOLATED
CONVECTION OVER THE SRN ZONES AS WE ENTER THE FINAL FEW DAYS OF
AUGUST.
PRELIMS TO FOLLOW BELOW...
15
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 94 75 96 75 96 / 20 10 10 10 10
MLU 90 74 95 74 95 / 50 20 10 10 10
DEQ 93 71 95 72 95 / 20 0 10 0 0
TXK 93 74 95 74 96 / 20 10 10 0 0
ELD 91 73 95 73 96 / 30 20 10 0 0
TYR 95 75 96 75 96 / 20 10 10 10 10
GGG 94 74 96 74 96 / 20 10 10 10 10
LFK 96 76 97 76 96 / 40 20 20 10 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
06
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
529 AM CDT MON AUG 18 2014
.AVIATION...
CLUSTER OF INTENSE TSTMS SLOWLY SHIFTING EAST ACROSS SW AR...MOVG
EAST OF KTXK TERMINAL...BUT NOW MOVG INTO KELD TERMINAL. STEEP
LAPSE RATES KEEPING MOST CLOUD BASES IN VFR...EVEN NEAR STORMS.
OUTFLOW BOUNDARIES MAY REGENERATE MIDDAY STORMS OVER KMLU AND
POSSIBLY KSHV TERMINALS...LESS CONVECTIVE ACTIVITY OVER NE TX EXPECTED.
HOWEVER...MID LVL DECKS WITH LGT RAIN MOVG EAST TOWARDS KTYR AND
KGGG. SW WINDS NEAR 10 KTS ACROSS MUCH OF AREA...MAINLY BTWN 18/15-21Z
TODAY...EXCEPT POSSIBLE GUSTS NEAR CONVECTION. ALSO...PATCHY FOG
POSSIBLE OVERNIGHT...MAINLY WHERE HEAVY RAIN FELL AT KTXK AND
KELD./VII/.
&&
.PREV DISCUSSION... /ISSUED 443 AM CDT MON AUG 18 2014/
DISCUSSION...
CONVECTION OVER SW AR HAS RAPIDLY DEVELOPED ON THE ERN PERIPHERY
OF AN MCV...WHERE RADAR AND SATELLITE INDICATE TO BE CENTERED NEAR
DEQ AS OF 09Z. LOCALLY HEAVY RAINFALL HAS BEEN EVIDENT PER
REFLECTIVITY IMAGERY...WHERE PERSISTENT TRAINING OF CONVECTION HAS
RESULTED IN WIDESPREAD 2-4 INCH RAINFALL TOTALS...PER DUAL POL
ESTIMATES. THE 00Z WRF HAS AGAIN INITIALIZED WELL THIS
MORNING WITH THE POSITION AND SLOWER MOVEMENT OF THE MCV...WITH THE
GFS CONTINUING TO SUFFER FROM FEEDBACK PROBLEMS AND SHOWS A MUCH
MORE RAPID PROGRESSION OF THE MCV ACROSS SW AR /EXITING THE AREA SHORTLY
AFTER 12Z/. MEANWHILE...THE LATEST HRRR IS OUT TO LUNCH AND DOES
NOT EVEN ACKNOWLEDGE THE CURRENT CONVECTION BUT DOES SUGGEST SCT
DEVELOPMENT LATER THIS MORNING CONTINUING THROUGH THE AFTERNOON
NEAR THE PARENT UPPER SHEAR AXIS OVER EXTREME NRN LA. THE CURRENT
HEAVY RAINFALL AXIS LINES UP WELL WITH A TONGUE OF GREATER SFC
THETA-E AND SBCAPES...WHICH RANGE FROM 1000-1500 J/KG AS OF 09Z.
THIS SHOULD CONTINUE TO FAVOR A SHORT TERM HEAVY RAINFALL THREAT
THIS MORNING OVER SW AR...AS THE MCV DRIFTS SLOWLY E THIS MORNING.
HAVE SEEN SCT CONVECTION DEVELOP FARTHER S ACROSS NRN
CADDO/BOSSIER/WEBSTER PARISHES AS WELL BENEATH THE MCV WHERE
850-700MB THETA-E RIDGING SHOULD RESULT IN CONVECTION EXPANDING E
ALONG/N OF THE I-20 CORRIDOR THROUGH MIDDAY. GIVEN THESE
OBSERVATIONS AND THE FACT THAT PW/S SHOULD RANGE FROM 2-2.25
INCHES...HAVE INCREASED POPS TO LIKELY THIS MORNING AND ADDED
HEAVY RAINFALL WORDING ACROSS MUCH OF SW AR...AND HAVE MAINTAINED
MID TO HIGH CHANCE POPS FARTHER S ACROSS NCNTRL LA AS THE MCV
SHIFTS E TO THE MS RIVER BY MIDDAY...AND ITS ATTENDANT SHEAR AXIS
DRIFTS ESE ACROSS THE AREA. THE AFTERNOON SEABREEZE SHOULD BE LESS
OF A FACTOR THIS AFTERNOON OVER DEEP E TX AS 850MB WINDS REMAIN
WSW BENEATH THE SHEAR AXIS...THUS SLIGHT CHANCE POPS SHOULD
SUFFICE FOR THESE AREAS. MAX TEMPS TODAY WILL AGAIN BE A TOUGH
CALL...BUT HAVE LOWERED TEMPS SLIGHTLY TO NEAR 90S OVER SCNTRL
AR/NCNTRL LA...WITH MID 90S EXPECTED ELSEWHERE AS THE AC CANOPY
BENEATH THE MCV GRADUALLY ERODES AND GIVES WAY TO SUNSHINE THIS
AFTERNOON.
THE WRF DOES SUGGEST A WEAK REFLECTION OF THE SHEAR AXIS REMAINING
IN PLACE ACROSS N LA/DEEP E TX THIS EVENING...AND THUS HAVE
MAINTAINED SLIGHT CHANCE POPS FOR THESE AREAS. AFTERWARDS...FLAT
500MB RIDGING IS EXPECTED TO SHIFT E INTO THE SRN PLAINS TUESDAY
FROM THE SRN ROCKIES...WITH A WEAK SEABREEZE POSSIBLE ACROSS DEEP
E TX/SRN SECTIONS OF NCNTRL LA DURING THE AFTERNOON AND EARLY
EVENING. UPPER RIDGING OVER THE WRN ATLANTIC AND ERN GULF REMAINS
PROGGED TO EXPAND FARTHER WNW WHILE ABSORBING THE 500MB RIDGE
CENTER OVER THE LOWER MS VALLEY WEDNESDAY...BEFORE CENTERING
ITSELF OVER THE MID-SOUTH REGION/LOWER MS VALLEY THURSDAY. STILL
SHOULD SEE A COUPLE MORE DAYS OF WEAK SEABREEZE CONVECTION ACROSS
OUR SRN ZONES WEDNESDAY AND THURSDAY...BEFORE LARGE SCALE
SUBSIDENCE BENEATH THE RIDGE INCREASES AS THE RIDGE CENTER BECOMES
POSITIONED OVER THE REGION.
PERSISTENCE WILL DOMINATE LATE THIS WEEK THROUGH THE REMAINDER OF
THE EXTENDED...WITH MAX TEMPS IN THE MID/UPPER 90S EACH DAY. STILL
CAN/T RULE OUT TRIPLE DIGIT HEAT OCCURRING LATE THIS WEEK THROUGH
EARLY NEXT WEEKEND ESPECIALLY OVER E TX/PORTIONS OF NW LA...WHICH
HAVE BEEN MOSTLY VOID OF WETTING RAINFALL THE LAST FEW WEEKS AND
WILL APPEAR TO MISS MUCH OF THE CONVECTION THIS MORNING. BOTH THE
GFS/ECMWF DO SUGGEST THAT THE RIDGE CENTER MAY SHIFT A TAD FARTHER
E INTO THE SE STATES BY MIDWEEK NEXT WEEK...ALLOWING WEAKNESSES
BENEATH THE RIDGE TO RETROGRADE W AND POSSIBLY ALLOW FOR ISOLATED
CONVECTION OVER THE SRN ZONES AS WE ENTER THE FINAL FEW DAYS OF
AUGUST.
PRELIMS TO FOLLOW BELOW...
15
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 94 75 96 75 96 / 30 10 10 10 10
MLU 90 74 95 74 95 / 50 20 10 10 10
DEQ 93 71 95 72 95 / 30 10 10 0 0
TXK 93 74 95 74 96 / 40 10 10 0 0
ELD 91 73 95 73 96 / 60 10 10 0 0
TYR 95 75 96 75 96 / 30 10 10 10 10
GGG 94 74 96 74 96 / 30 10 10 10 10
LFK 96 76 97 76 96 / 20 20 20 10 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
443 AM CDT MON AUG 18 2014
.DISCUSSION...
CONVECTION OVER SW AR HAS RAPIDLY DEVELOPED ON THE ERN PERIPHERY
OF AN MCV...WHERE RADAR AND SATELLITE INDICATE TO BE CENTERED NEAR
DEQ AS OF 09Z. LOCALLY HEAVY RAINFALL HAS BEEN EVIDENT PER
REFLECTIVITY IMAGERY...WHERE PERSISTENT TRAINING OF CONVECTION HAS
RESULTED IN WIDESPREAD 2-4 INCH RAINFALL TOTALS...PER DUAL POL
ESTIMATES. THE 00Z WRF HAS AGAIN INITIALIZED WELL THIS
MORNING WITH THE POSITION AND SLOWER MOVEMENT OF THE MCV...WITH THE
GFS CONTINUING TO SUFFER FROM FEEDBACK PROBLEMS AND SHOWS A MUCH
MORE RAPID PROGRESSION OF THE MCV ACROSS SW AR /EXITING THE AREA SHORTLY
AFTER 12Z/. MEANWHILE...THE LATEST HRRR IS OUT TO LUNCH AND DOES
NOT EVEN ACKNOWLEDGE THE CURRENT CONVECTION BUT DOES SUGGEST SCT
DEVELOPMENT LATER THIS MORNING CONTINUING THROUGH THE AFTERNOON
NEAR THE PARENT UPPER SHEAR AXIS OVER EXTREME NRN LA. THE CURRENT
HEAVY RAINFALL AXIS LINES UP WELL WITH A TONGUE OF GREATER SFC
THETA-E AND SBCAPES...WHICH RANGE FROM 1000-1500 J/KG AS OF 09Z.
THIS SHOULD CONTINUE TO FAVOR A SHORT TERM HEAVY RAINFALL THREAT
THIS MORNING OVER SW AR...AS THE MCV DRIFTS SLOWLY E THIS MORNING.
HAVE SEEN SCT CONVECTION DEVELOP FARTHER S ACROSS NRN
CADDO/BOSSIER/WEBSTER PARISHES AS WELL BENEATH THE MCV WHERE
850-700MB THETA-E RIDGING SHOULD RESULT IN CONVECTION EXPANDING E
ALONG/N OF THE I-20 CORRIDOR THROUGH MIDDAY. GIVEN THESE
OBSERVATIONS AND THE FACT THAT PW/S SHOULD RANGE FROM 2-2.25
INCHES...HAVE INCREASED POPS TO LIKELY THIS MORNING AND ADDED
HEAVY RAINFALL WORDING ACROSS MUCH OF SW AR...AND HAVE MAINTAINED
MID TO HIGH CHANCE POPS FARTHER S ACROSS NCNTRL LA AS THE MCV
SHIFTS E TO THE MS RIVER BY MIDDAY...AND ITS ATTENDANT SHEAR AXIS
DRIFTS ESE ACROSS THE AREA. THE AFTERNOON SEABREEZE SHOULD BE LESS
OF A FACTOR THIS AFTERNOON OVER DEEP E TX AS 850MB WINDS REMAIN
WSW BENEATH THE SHEAR AXIS...THUS SLIGHT CHANCE POPS SHOULD
SUFFICE FOR THESE AREAS. MAX TEMPS TODAY WILL AGAIN BE A TOUGH
CALL...BUT HAVE LOWERED TEMPS SLIGHTLY TO NEAR 90S OVER SCNTRL
AR/NCNTRL LA...WITH MID 90S EXPECTED ELSEWHERE AS THE AC CANOPY
BENEATH THE MCV GRADUALLY ERODES AND GIVES WAY TO SUNSHINE THIS
AFTERNOON.
THE WRF DOES SUGGEST A WEAK REFLECTION OF THE SHEAR AXIS REMAINING
IN PLACE ACROSS N LA/DEEP E TX THIS EVENING...AND THUS HAVE
MAINTAINED SLIGHT CHANCE POPS FOR THESE AREAS. AFTERWARDS...FLAT
500MB RIDGING IS EXPECTED TO SHIFT E INTO THE SRN PLAINS TUESDAY
FROM THE SRN ROCKIES...WITH A WEAK SEABREEZE POSSIBLE ACROSS DEEP
E TX/SRN SECTIONS OF NCNTRL LA DURING THE AFTERNOON AND EARLY
EVENING. UPPER RIDGING OVER THE WRN ATLANTIC AND ERN GULF REMAINS
PROGGED TO EXPAND FARTHER WNW WHILE ABSORBING THE 500MB RIDGE
CENTER OVER THE LOWER MS VALLEY WEDNESDAY...BEFORE CENTERING
ITSELF OVER THE MID-SOUTH REGION/LOWER MS VALLEY THURSDAY. STILL
SHOULD SEE A COUPLE MORE DAYS OF WEAK SEABREEZE CONVECTION ACROSS
OUR SRN ZONES WEDNESDAY AND THURSDAY...BEFORE LARGE SCALE
SUBSIDENCE BENEATH THE RIDGE INCREASES AS THE RIDGE CENTER BECOMES
POSITIONED OVER THE REGION.
PERSISTENCE WILL DOMINATE LATE THIS WEEK THROUGH THE REMAINDER OF
THE EXTENDED...WITH MAX TEMPS IN THE MID/UPPER 90S EACH DAY. STILL
CAN/T RULE OUT TRIPLE DIGIT HEAT OCCURRING LATE THIS WEEK THROUGH
EARLY NEXT WEEKEND ESPECIALLY OVER E TX/PORTIONS OF NW LA...WHICH
HAVE BEEN MOSTLY VOID OF WETTING RAINFALL THE LAST FEW WEEKS AND
WILL APPEAR TO MISS MUCH OF THE CONVECTION THIS MORNING. BOTH THE
GFS/ECMWF DO SUGGEST THAT THE RIDGE CENTER MAY SHIFT A TAD FARTHER
E INTO THE SE STATES BY MIDWEEK NEXT WEEK...ALLOWING WEAKNESSES
BENEATH THE RIDGE TO RETROGRADE W AND POSSIBLY ALLOW FOR ISOLATED
CONVECTION OVER THE SRN ZONES AS WE ENTER THE FINAL FEW DAYS OF
AUGUST.
PRELIMS TO FOLLOW BELOW...
15
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 94 75 96 75 96 / 30 10 10 10 10
MLU 90 74 95 74 95 / 50 20 10 10 10
DEQ 93 71 95 72 95 / 30 10 10 0 0
TXK 93 74 95 74 96 / 40 10 10 0 0
ELD 91 73 95 73 96 / 60 10 10 0 0
TYR 95 75 96 75 96 / 30 10 10 10 10
GGG 94 74 96 74 96 / 30 10 10 10 10
LFK 96 76 97 76 96 / 20 20 20 10 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
15
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
1157 PM CDT SUN AUG 17 2014
.AVIATION...
ONE LONE LIGHT RAIN SHWR LEFT BEHIND OF THE EVENING`S CONVECTION...
AND FCST MODEL DEPICTION OF REDEVELOPMENT TONIGHT HAS THUS FAR NOT
PANNED OUT AT ALL. FOR THIS REASON...HAVE OPTED TO DISCOUNT THIS DESPITE
HAVING SOME MODEL GUIDANCE THAT SUGGESTED HIGH CONFIDENCE OF
PREVAILING TSTMS BY SUNRISE. CANNOT RULE OUT A FEW ISOLD INSTANCES
OF REDEVELOPMENT DURING THE OVERNIGHT HOURS...HOWEVER.
ADDITIONALLY...MVFR STRATUS DEVELOPMENT IS EXPECTED AT MOST
SITES AROUND SUNRISE...WHICH WILL LIFT ONCE AGAIN BY AROUND MID
MORNING. ISOLD/SCT CONVECTION IS EXPECTED TO DEVELOP DURING PEAK
HEATING ONCE AGAIN...AND WILL LIKELY DIMINISH SHORTLY AFTER
SUNSET. /12/
&&
.PREV DISCUSSION... /ISSUED 959 PM CDT SUN AUG 17 2014/
DISCUSSION...
DIFFICULT UPDATE THIS EVENING AS WE CONTINUE TO DEAL WITH A WEAK
TO MODERATELY UNSTABLE AIRMASS IN PLACE...A SHORTWAVE NEAR THE
I-30 CORRIDOR OF NE TX/SE OK/SW AR AND INCREASING PRECIPITABLE
WATER VALUES FROM THE WEST ASSOCIATED WITH THE SHORTWAVE.
CONVECTION THUS FAR THIS EVENING HAS BEEN VERY UNEVENTFUL EXCEPT
FOR WIDELY SCATTERED CONVECTION ASSOCIATED WITH A SEA BREEZE
BOUNDARY THAT MOVED A GOOD BIT FURTHER NORTH INTO DEEP EAST TEXAS
AND NORTH CENTRAL LOUISIANA COMPARED TO SATURDAY. AS OF THIS
WRITING...ALL CONVECTION HAS DISSIPATED BUT WE WILL CONTINUE TO
LOOK TO OUR NORTH AND WEST OVERNIGHT FOR THE POSSIBILITY OF
REDEVELOPMENT.
THE ARGUMENTS AGAINST REDEVELOPMENT INCLUDE THE FACT THAT A WEAK
WSW ORIENTED LOW LEVEL JET NEAR 20KTS IS VEERED A LITTLE MORE THAN
I WOULD LIKE TO SEE IT AND THAT WHILE PWATS SHOULD INCREASE
OVERNIGHT SLIGHTLY...MODELS ARE REALLY OVERDOING THE DEPTH OF
MOISTURE IN ASSOCIATION WITH THIS SHORTWAVE/SHEAR AXIS. THE GFS
CONTINUES TO BE USELESS AS IT SUFFERS FROM CONVECTIVE FEEDBACK
PROBLEMS AND THE LATEST HRRR HAS COME IN MUCH DRIER OVERNIGHT THAN
ITS PREVIOUS RUN SUGGESTED. HOWEVER...THE LATEST 00Z NAM SHOWS
QUITE A BIT OF REDEVELOPMENT OVERNIGHT MAINLY NORTH OF THE I-20
CORRIDOR ACROSS EXTREME NE TX/SE OK AND ESPECIALLY SW AR.
THIS LEADS TO A LOW CONFIDENCE FORECAST BUT ALL VARIABLES LEAD ME
TO RAISE POPS SLIGHTLY ACROSS OUR NORTHERN MOST ZONES AND TO TRIM
POPS BACK SLIGHTLY ACROSS THE I-20 CORRIDOR OF NE TX AND NORTHERN
LOUISIANA AS WELL AS POINTS SOUTH.
ONLY MADE SLIGHT CHANGES TO TEMPS OVERNIGHT AS SOME 02Z LOCATIONS
WERE ALREADY NEAR FCST MINS. OTHERWISE...ROUTINE DEWPOINT AND RH
GRIDS WERE ADJUSTED TO MIMIC CURRENT TRENDS...OTHERWISE NO OTHER
SIGNIFICANT CHANGES WERE MADE. /13/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 76 93 75 96 75 / 30 50 20 20 10
MLU 74 90 74 95 74 / 30 50 20 20 10
DEQ 72 94 71 95 72 / 40 20 10 0 10
TXK 75 93 73 95 74 / 40 40 10 10 10
ELD 74 92 73 95 74 / 40 50 20 20 10
TYR 75 94 74 96 75 / 30 40 10 0 10
GGG 75 94 74 96 75 / 30 40 10 10 10
LFK 75 94 75 96 76 / 20 30 20 20 10
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
12
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
932 PM EDT TUE AUG 19 2014
.SYNOPSIS...
LOW PRESSURE WILL CONTINUE TO DRIFT EAST FROM NORTHEASTERN NORTH
CAROLINA THROUGH TONIGHT...WITH AN ONSHORE FLOW PERSISTING INTO
THURSDAY NIGHT. A COLD FRONT WILL MOVE THROUGH THE AREA FROM THE
NORTHWEST FRIDAY WITH MORE ONSHORE FLOW FRIDAY NIGHT INTO NEXT
WEEK.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 01Z...1009MB SFC LOW IS OFFSHORE FROM THE VA/NC BORDER AND
DRIFTING EAST. A LIGHT ONSHORE/SELY FLOW IS ACROSS THE CENTRAL
MID-ATLANTIC. UPSTREAM...A SHORTWAVE IS MOVING EAST THROUGH THE
MIDWEST STATES WITH AN MCS PUSHING EAST OVER LAKE ERIE (CURRENTLY
NEAR CLEVELAND).
WILL NEED TO MONITOR DEVELOPMENT ALONG THE SOUTHERN END OF THE MCS
(CURRENTLY OVER COLUMBUS)...FOR DOWNSTREAM AREAS LIKE CUMBERLAND
MD OVERNIGHT. HOWEVER...THE LOW IS OCCLUDED AND EASTWARD PROGRESS
SHOULD BE SOMEWHAT LIMITED. THE 22Z HRRR SUGGEST A SUPPLEMENTAL
VORT LOBE SHIFTS ACTIVITY EAST INTO NWRN PARTS OF THE CWA
WEDNESDAY MORNING. TOOK THIS APPROACH IN THE GRIDS WITH CHANCE
POPS ENTERING THE NORTHWEST AFTER 6 AM.
SHEAR INCREASES OVER THE AREA WEDNESDAY AHEAD OF THE LOW THAT WILL
CONTINUE DRIFTING EAST ACROSS THE GREAT LAKES. TIMING OF VORT
MAX/TROUGH PASSAGE EAST FROM THE SHENANDOAH VALLEY SHOULD BE
CLOSE TO PRIME DIURNAL HEATING...SO MORE ACTIVITY IS EXPECTED THAN
RECENT DAYS. HOWEVER...THE ONSHORE FLOW SHOULD CONTINUE TO LIMIT
STORMS EAST FROM THE BLUE RIDGE. MAINTAINED LIKELY POPS FOR LATE
AFTERNOON/EARLY EVENING FOR NRN SECTIONS OF THE CWA...MAINLY WEST
OF I-95. MAX TEMPS MID TO UPR 80S DEPENDING ON MID LEVEL CLOUD
COVER CLEARING.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
THE DISTURBANCE WILL MOVE OFF THE COAST LATE WEDNESDAY NIGHT AND
SHOWERS MAY LINGER EAST OF THE BLUE RIDGE INTO THURSDAY. NORTHWEST
FLOW ALOFT WILL ALLOW A UPPER LOW TO APPROACH THE REGION AND MOVE
ACROSS THE NORTHEAST THURSDAY. THUNDERSTORMS ARE POSSIBLE THURSDAY
AFTERNOON WEST OF THE BLUE RIDGE AS THE EXIT REGION OF AN UPPER
LEVEL JET APPROACHES. SFC FLOW IS LIGHT AND WESTERLY WHICH WILL
KEEP DEWPTS IN THE LOW TO MID 60S THURSDAY. INSTABILITY WILL BE
BASED ON CLOUD COVER WHICH IS HARD TO SAY RIGHT NOW BUT THE MORE
BREAKS THE GREATER THE INSTABILITY. MARGINAL SHEAR OF 25 KTS IS
EXPECTED AT THIS TIME. AT THIS TIME...SVR STORM POTENTIAL IS LOW.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
AN UPPER LEVEL LOW RIDING AROUND THE EAST SIDE OF A DEVELOPING
SUBTROPICAL RIDGE WILL CROSS JUST NORTH OF THE AREA THURSDAY NIGHT
AND FRIDAY. MANY LOCATIONS...PARTICULARLY IN MARYLAND...COULD SEE
PERIODS OF HEAVY RAIN AND AN ISOLATED THUNDERSTORM THROUGH THE NIGHT
THURSDAY. THE COLLOCATION OF ENHANCED LIFT FROM THE LEFT EXIT REGION
OF A JET STREAK ROUNDING THE SOUTHWESTERN SIDE OF THE UPPER LEVEL
LOW LATE THURSDAY NIGHT AS WELL AS A STALLED BOUNDARY AT THE SURFACE
WILL FURTHER ENHANCE THE POTENTIAL FOR RAINFALL ACROSS THE AREA.
OVERALL HAVE HIGHEST POPS ACROSS MARYLAND WITH SHOWERS AND ISOLATED
THUNDERSTORMS THURSDAY NIGHT AND INTO FRIDAY MORNING.
THE AFOREMENTIONED SURFACE BOUNDARY WILL REMAIN NEAR THE AREA
THROUGH FRIDAY AFTERNOON AS A COASTAL LOW FORMS OFF OF CAPE
HATTERAS. WITH MODEST MOISTURE ADVECTION OCCURRING IN THE LOW AND
MID LEVELS...SHOWERS AND ISOLATED THUNDERSTORMS REMAIN POSSIBLE
FRIDAY EVENING...ESPECIALLY OVER THE EASTERN HALF OF THE CWA.
OVERALL RAINFALL COVERAGE SHOULD BE SIGNIFICANTLY LESS FRIDAY
EVENING THAN THURSDAY NIGHT.
HIGH PRESSURE WILL RIDGE DOWN INTO THE AREA BEGINNING FRIDAY NIGHT.
THIS WILL WORK WITH THE LOW PARKED OFF THE SOUTHEAST COAST TO BRING
ONSHORE FLOW INTO THE AREA. THIS MARINE AIRMASS WILL KEEP MOST OF
THE AREA...PARTICULARLY EAST OF THE BLUE RIDGE...CLOUDY HUMID AND
COOL THROUGH THE WEEKEND AND LIKELY INTO THE BEGINNING OF NEXT WEEK.
THUNDERSTORMS ARE UNLIKELY WITH THIS AIRMASS...BUT ISOLATED LIGHT
RAIN WILL BE POSSIBLE MOSTLY SATURDAY...PARTICULARLY IN AREAS WHERE
THERE IS AN UPSLOPE COMPONENT TO THE FLOW. EXPECT MORE BREAKS IN
THE CLOUDS WEST OF THE BLUE RIDGE...THOUGH LIGHT RAIN REMAINS
POSSIBLE SATURDAY AND SUNDAY THERE AS WELL.
HIGH PRESSURE EXTENDING DOWN THE EAST COAST WILL WEAKEN EARLY NEXT
WEEK AS A COLD FRONT APPROACHES FROM THE WEST. THIS WILL LIKELY
SIGNAL THE RETURN OF SOUTHERLY FLOW AND TEMPERATURES BECOMING MORE
SEASONABLE. OVERALL THE COOLER THAN NORMAL TREND OF THE SUMMER WILL
CONTINUE THROUGH THE LONG TERM WITH HIGHS MOSTLY IN THE UPPER 70S AS
THE COOL MARINE AIRMASS COVERS THE AREA FOR THE WEEKEND AND MONDAY.
TUESDAY WILL SEE HIGHS IN THE LOWER 80S AS WEAK WARM AIR ADVECTION
BEGINS OVER THE REGION.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
ONSHORE FLOW CONTINUES AND MVFR/IFR CIGS EXPECTED LATE TONIGHT.
IFR CIGS/VSBYS MOST LIKELY AT CHO AND MRB WEDNESDAY MORNING. A
DISTURBANCE MOVES ACROSS THE REGION WEDNESDAY AND SHRA AND VCTS
ARE POSSIBLE. AT THIS TIME...THREAT OF TS IS LOW AND THEREFORE NOT
IN THE TAFS. ANOTHER DISTURBANCE APPROACHES THURSDAY AND SHRA AND
TSRA IS POSSIBLE IN THE AFTERNOON.
PERIODS OF LOW CEILINGS ARE EXPECTED AS AN UPPER LEVEL DISTURBANCE
CROSSES THE AREA THURSDAY NIGHT AND THEN AGAIN OVER THE WEEKEND AND
INTO EARLY NEXT WEEK AS A MARINE AIRMASS SETTLES INTO THE AREA.
&&
.MARINE...
LIGHT ONSHORE FLOW CONTINUES THROUGH THURSDAY AND WILL STAY BELOW
SCA CRITERIA. SHOWERS AND ISOLATED THUNDERSTORMS ARE POSSIBLE
WEDNESDAY AFTERNOON AND EVENING AND AGAIN THURSDAY AFTERNOON.
CONFIDENCE IS LOW IN THE OCCURRENCE OF ANY MARINE HAZARDS THROUGH
THE LONG TERM.
&&
.TIDES/COASTAL FLOODING...
AN ONSHORE FLOW WILL CONTINUE THROUGH TONIGHT...BUT IT WILL REMAIN
WEAK. TIDAL ANOMALIES AROUND ONE-HALF FOOT ABOVE NORMAL WILL
PERSIST THROUGH TONIGHT. WATER LEVELS WILL BE CLOSE TO MINOR
FLOODING THRESHOLDS DURING THE HIGH TIDE CYCLE LATE TONIGHT BUT
EXPECTATION IS THAT WATER LEVELS WILL REMAIN BELOW MINOR FLOODING
THRESHOLDS SINCE THE ONSHORE FLOW IS WEAK.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BAJ/HAS
NEAR TERM...BAJ
SHORT TERM...HAS
LONG TERM...CEB
AVIATION...BAJ/HAS/CEB
MARINE...BAJ/HAS/CEB
TIDES/COASTAL FLOODING...LWX
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
645 PM EDT MON AUG 18 2014
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL DEVELOP OVER VIRGINIA TONIGHT BEFORE
MOVING OFF THE COAST TUESDAY. WEAK HIGH PRESSURE RETURNS ON
WEDNESDAY BEFORE ANOTHER SYSTEM OVER THE GREAT LAKES MOVES INTO
THE MID ATLANTIC STATES FOR THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH TUESDAY/...
UPDATE THIS EVENING TO DROP THE WATCH AND TWEAK THE POPS SOME
OVERNIGHT. AS SECONDARY LOW DEVELOPING OVER CENTRAL NC SHOULD
BECOME THE DOMINANT LOW OVERNIGHT LIFTING NORTHEAST INTO NORTHEAST
NC AND SOUTHEAST VA AND LOWER BAY. TRENDING TOWARDS THE HRRR POP
TRENDS WITH THE MOST WIDESPREAD SHOWERS AND STORMS ACROSS THE
SOUTHERN TWO THIRDS OF THE FORECAST AREA. EXPECT SCATTERED SHOWERS
AND STORMS WELL NORTH AND NORTHWEST OF RIC.
ONCE THE LOW BEGINS TO DEVELOP THIS EVENING...EXPECT TO SEE MORE
SHOWERS AND AREAS OF RAIN FORM ALONG AN NORTH OF THE FRONT WITH
MORE CONVECTIVE PRECIPITATION TO THE SOUTH OF IT. SOME AREAS COULD SEE
0.50 - 1 INCH OF RAIN AS PW CONTINUE TO RUN A LITTLE OVER 2 INCHES
IN A VERY MOIST ATMOSPHERE. HAVE ALSO BUMPED UP OVERNIGHT LOWS DUE
TO THE MORE HUMID AIRMASS.
FOR TUESDAY...THE LOW SLOWLY SLIDES OFF THE VA COAST AND HAS SOME
WRAP AROUND MOISTURE SO HAVE HELD ON TO THE PCPN A LITTLE LONGER
ACROSS THE DELMARVA AS THE 12Z NAM IS SLOWER THAN THE 12Z GFS IN
PULLING THE LOW OUT. LATER IN THE AFTERNOON...WILL GET THE SFC
BOUNDARY SLIDING DOWN INTO THE TIDEWATER AND NE NC SO MORE SHOWERS
ARE POSSIBLE THERE. FOR TEMPERATURES HAVE LEAN A LITTLE LOW
ESPECIALLY TOWARD THE NORTH THINKING THAT CLOUDS WILL LINGER AND
LIMIT THE DAY TIME HEATING.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
FROM TUESDAY NIGHT THROUGH THURSDAY...THE MODELS ARE SHOWING LOTS
OF VARIABLIITY WITH THE MOVEMENT OF SHORTWAVE ENERGY IN THE
NORTHWEST FLOW AS THE UPPER RIDGE OVER THE MS VALLEY BUILDS AND
THE UPPER LOW OVER THE GREAT LAKES IS SLOW TO MOVE EAST. WEDNESDAY
LOOKS TO BE THE DRIER OF THE TWO DAY AS THE EXITING LOW OFF THE
COAST ALLOWS FOR WEAK HIGH PRESSURE OVER THE NE TO NOSE SOUTHWARD
INTO THE MID ATLANTIC STATES AND THE MOISTURE LESSENS. BUT BY
THURSDAY...THE NW FLOW IS MORE ESTABLISHED AND WITH CONVECTION TO
THE NORTHWEST AND THE REGION IN A GOOD POSITION ON THE EDGE OF THE
RIDGE...COULD EASILY SEE CONVECTION DROP SE INTO THE REGION. SO
HAVE VERY LITTLE PCPN ON WEDNESDAY WITH HIGHER CHANCE POPS ON
THURSDAY. BUT CONFIDENCE IN THE OVER PATTERN IS LOW DUE TO THE
MODEL UNCERTAINTY FROM RUN TO RUN.
FOR TEMPERATURES...HAVE ALLOWED FOR SOME ADDITIONAL HEATING ON WED
AND THU DUE TO MORE SUNSHINE AND ALSO DUE TO THE WEST/NW FLOW
ALOFT.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
UNSETTLED WEATHER PATTERN CONTINUES INTO THE EXTENDED PERIOD AS NWLY
FLOW ALOFT DEVELOPS. TEMPS WILL BE NEAR TO SLIGHTLY BELOW
SEASONABLE...LATE SUMMER NORMS.
WHILE MEDIUM RANGE GUIDANCE CONTINUES TO STRUGGLE HANDLING THE
SPLIT/BLOCKY FLOW OVER THE HIGHER LATITUDES...MODELS HAVE BECOME
MORE STABLE WITH RESOLVING SRN STREAM ENERGY OVER THE OH VALLEY AND
MID-ATLANTIC REGION. THIS THANKS TO UPPER/SFC HIGH PRESSURE FROM THE
SE STATES EWD OFF THE COAST. WITH THAT SAID...FLOW AMPLIFIES OVER
THE ERN CONUS AS MID LEVEL HIGH PRESSURE BUILDS OVER THE CNTRL US
AND LOW PRESSURE REMAINS OVER THE NE US. THIS WILL PLACE THE
MID-ATLANTIC STATES IN NWLY FLOW ALOFT...OPENING THE DOOR FOR
SHORTWAVE ENERGY IN THE UPPER FLOW. QUASI-STATIONARY BOUNDARY WILL
LOCATE OVER THE REGION...JUST TO THE SOUTH. MOISTURE WILL NOT BE A
LIMITATION WITH PWATS PROGGED AROUND 2 INCHES (+1 STD DEV) AND
DEWPOINTS IN THE MID-UPPER 60S. ANTICIPATE A DIURNAL TREND WITH
SHOWERS/THUNDERSTORMS...BUT UPSTREAM MCS DEVELOPMENT MAY SPILL INTO
THE REGION DURING THE OVERNIGHT HOURS THRU THE WEEKEND. HIGHER POPS
MAY BE WARRANTED...BUT BASED ON THE DEGREE OF UNCERTAINTY AND
TIMING...WILL STICK MORE TO CLIMO WITH CHANCE POPS DURING THE
AFTERNOON AND EVENING. COULD BEGIN TO SEE A DRYING TREND BY LATE IN
THE WEEKEND INTO EARLY NEXT WEEK AS THE UPPER HIGH BUILDS
EWD...SHUNTING THE BEST MOISTURE OFFSHORE.
WITH THE LATEST MODEL RUNS PLACING THE FRONT SOUTH OF THE LOCAL
AREA...NLY FLOW AND FALLING THICKNESSES WILL LIKELY YIELD TEMPS IN
THE LOW-MID 80S. LOW-MID 80S TO CONTINUE THRU THE WEEKEND...WARMING
BACK INTO THE MID 80S BY EARLY NEXT WEEK.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
MID LVL TROF AND ASSOCIATED SFC LO PRES WILL CROSS THE REGION THIS
AFTN INTO MIDDAY TUE. EXPECT SHOWERS AND POSSIBLY A TSTM AT THE
TAF SITES INTO THIS EVENG...WITH JUST RAIN OR RAIN SHOWERS AT THE
TAF SITES FM THIS EVENG INTO MIDDAY TUE. SHOULD HAVE MAINLY VFR OR
MVFR CONDITIONS DURING THIS TIME PERIOD...BUT ISLTD IFR CONDITIONS
COULD OCCUR IN ANY HEAVIER SHOWERS OR TSTMS. MAINLY VFR CONDITIONS
EXPECTED LATE TUE THRU THU...BUT ISLTD OR SCTD PCPN (ESPLY WED AND
THU AFTN/EVENG) COULD PRODUCE LWR CIGS AND VSBYS.
&&
.MARINE...
UNSETTLED WEATHER PATTERN WILL PREVAIL OVER THE WATERS THRU THE
FORECAST PERIOD...BUT SCA CONDITIONS ARE NOT ANTICIPATED.
AREA OF LOW PRESSURE HAS LOCATED OVER WV WITH A FRONTAL BOUNDARY
EXTENDING EWD OVER SRN VA AND THE LOWER BAY. MEANWHILE...HIGH
PRESSURE BUILDS OVER THE NE STATES. THE RESULT IS GENERALLY ONSHORE
AROUND 10 KT. WAVES/SEAS AVG 1-2 FT. SFC LOW WEAKENS OVER THE CNTRL
APPALACHIANS AS AN ADDITIONAL AREA OF LOW PRESSURE DEVELOPS OVER THE
WATERS. WITH THE SFC LOW OVER THE WATERS...FLOW OVER THE COASTAL
WATERS (ON THE ERN PERIPHERY OF THE LOW) WILL BE SW OVER THE SRN
WATERS...VEERING TO E OVER THE NRN WATERS...AVG 10-15 KT. SCA
CONDITIONS ARE NOT ANTICIPATED. SEAS WILL BUILD ONLY TO 2-3 FT WITH
WAVES AVG 1-2 FT. SFC LOW SLOWLY PUSHES OFFSHORE LATE TUES-TUES
NIGHT AS HIGH PRESSURE OFF THE NE COAST RIDGES SWD OVER THE NRN
WATERS. FLOW REMAINS GENERALLY ONSHORE...AOB 15 KT. LOW PRESSURE
LINGERS OFF THE MID-ATLANTIC COAST THRU THE END OF THE WORK WEEK AND
INTO THE WEEKEND AS A FRONTAL BOUNDARY REMAINS SOUTH OF THE WATERS.
THE RESULT WILL BE ONGOING ONSHORE/NELY FLOW. GRADIENT WILL REMAIN
WEAK (AOB 15 KT)...BUT PERSISTENT NE FETCH MAY PUSH SEAS UPWARDS OF
5 FT IN THE NRN COASTAL WATERS FRIDAY NIGHT THRU THE WEEKEND.
UNDERCUT WAVEWATCH AS GFS IS NOT THE PREFERRED MEDIUM RANGE MODEL.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ESS
NEAR TERM...ESS/JAO
SHORT TERM...ESS
LONG TERM...SAM
AVIATION...TMG
MARINE...SAM
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
230 AM EDT MON AUG 18 2014
.SYNOPSIS...
A TROUGH OF LOW PRESSURE WILL SLIDE OFF THE COAST TONIGHT. A COOL
FRONT WILL DROP SOUTH TOWARDS THE REGION LATE TONIGHT AND MONDAY.
LOW PRESSURE WILL MOVE ALONG THE FRONT FROM THE OHIO VALLEY
TOWARDS THE MID-ATLANTIC REGION LATE TONIGHT THROUGH MONDAY
NIGHT...BEFORE MOVING OFF THE COAST DURING TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
UPDATE OF THE POPS ACROSS THE MD EASTERN TO ACCOUNT FOR A WEAK WAVE
IN THE UPPER LEVELS WHICH IS PRODUCING SOME ISOLD TO SCT SHOWERS.
THE RAP AND HRRR BOTH HAVE A DECENT HANDLE ON THESE SHOWERS WHICH
COULD HOLD ON THROUGH AROUND 06Z. THE SHOWERS SHOULD BE LIMITED IN
OVERALL COVERAGE...BUT WILL TRAIN OVER A FEW LOCATIONS THROUGH
06Z. SHOWER ACTIVITY SHOULD DECREASE AND SHIFT OFF THE COAST
SHORTLY AFTER 06Z.
A TROF OF LO PRES WILL SLIDE OFF THE CST TNGT. SOME WEAK ENERGY
COMBINED WITH MARGINAL INSTABILITY COULD TRIGGER AN ISLTD SHOWER
OR TSTM THIS EVENG. OTHERWISE...GENERALLY PARTLY CLOUDY AND MILD
TNGT WITH LOWS RANGING FM THE MID 60S TO LWR 70S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY/...
WARM AND MORE HUMID MON THRU WED...AS WESTERLY (ZONAL) FLO ALOFT
DOMINATES THE REGION. AN AREA OF DEEPER LO LVL MOIST ASSOCIATED
WITH A MID LVL TROF AND SFC LO PRES WILL AFFECT THE REGION MON
AFTN INTO AT LEAST MIDDAY TUE. THUS...WILL HAVE THE HIGHEST POPS
(30-60%) FOR SHOWERS AND POSSIBLE TSTMS DURING THIS TIME PERIOD.
THE PRESENCE OF AN INCREASINGLY UNSTABLE AIRMASS AND PW VALUES
~1.75-2.00 INCHES WILL ALSO MEAN STRONGER SHOWERS OR TSTMS COULD
CONTAIN HEAVY RAINFALL. POPS DECREASE TO SLGT CHC OR NO CHC (14%)
LATE TUE INTO WED MORNG...DUE TO SUBSIDENCE BEHIND THE DEPARTING
WAVE OF LO PRES. MORE SHRTWV ENERGY IN WEAK UPR AIR TROFINESS WILL
RESULT IN SLGT (20%) TO SML CHC (30%) POPS ACRS THE AREA ON
WED...ESPLY IN THE AFTN/EVENG.
MAX TEMPS WILL MAINLY RANGE FM THE MID 80S TO NEAR 90 THRU THE
PERIOD...WITH MIN TEMPS RANGING FM THE MID 60S TO LWR 70S.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
BLOCKY PATTERN OVER ERN CANADA AND THE NRN ATLANTIC WILL RESULT IN
AN UNSETTLED WEATHER PATTERN THROUGH THE PERIOD. TEMPS WILL BE NEAR
SEASONABLE...LATE SUMMER NORMS.
SPLIT/BLOCKY FLOW IS TYPICALLY PROBLEMATIC FOR MEDIUM RANGE
GUIDANCE...AND THIS TIME IS NO EXCEPTION. CONTINUE TO TREND FORECAST
TOWARD THE ECMWF AND ENSEMBLE MEANS BASED ON RUN TO RUN CONSISTENCY
AND WPC GUIDANCE...BUT CONFIDENCE IS NOT HIGH ATTM. THIS GUIDANCE
REMAINS BTWN THE MORE AMPLIFIED 17/12Z GFS AND THE NEARLY ZONAL
17/12Z CANADIAN. WITH THAT SAID...FLOW AMPLIFIES OVER THE ERN CONUS
AS MID LEVEL HIGH PRESSURE BUILDS OVER THE GULF STATES.
MEANWHILE...ANOMALOUS HIGH PRESSURE BUILDS OVER ERN CANADA. SRN
STREAM ENERGY OVER THE GREAT LAKES/NE STATES WILL PUSH A SHORTWAVE
INTO THE NE STATES WITH TROUGHING EXTENDING SWD ALONG THE ERN
SEABOARD. QUASI-STATIONARY BOUNDARY WILL SETTLE ACROSS THE
MID-ATLANTIC REGION (ABOUT 100 MILES FARTHER SOUTH THAN 24 HOURS
AGO) DURING THE PERIOD AS FLOW ALOFT REMAINS GENERALLY WLY. THE
FRONT WILL BE THE FOCUS FOR SHOWERS/THUNDERSTORMS THRU THE PERIOD AS
WEAK PERTURBATIONS IN THE FLOW PRODUCE WAVES OF LOW PRESSURE ALONG
THE BOUNDARY. WARM/HUMID AIRMASS WILL BE IN PLACE WITH DEWPOINTS IN
THE UPPER 60S TO LOW 70S AND TYPICAL LATE SUMMER PWATS BTWN 1.5 AND
2 INCHES. HOWEVER...LACK OF CONFIDENCE FACTORS INTO RELATIVELY LOW
CHANCE POPS. CLIMO THIS TIME OF YEAR IS AROUND 20 PCT...BUT WILL GO
HIGHER DURING THE AFTERNOON (30-40%) AND NEAR CLIMO OVERNIGHT DUE TO
MOIST AND MARGINALLY UNSTABLE AIRMASS. IF THE TROUGH PUSHES OFFSHORE
FRI NIGHT-SAT...PERTURBATIONS IN THE NW FLOW COULD BRING ADDITIONAL
CHANCES OF PRECIP TO THE REGION THRU THE WEEKEND...ESPECIALLY IN THE
NE.
WARM THURS AND FRI WITH HIGHS IN THE UPPER 80S TO AROUND
90...COOLING OFF DUE TO CLOUDS/PRECIP THIS WEEKEND. LOW LEVEL
THICKNESSES YIELD TEMPS GENERALLY IN THE MID 80S SAT AND SUN.
OVERNIGHT LOWS GENERALLY IN THE UPPER 60S TO LOWER 70S THRU THE
PERIOD.
&&
.AVIATION /07Z MONDAY THROUGH FRIDAY/...
VFR CONDITIONS WILL PREVAIL THE REST OF TONIGHT WITH PATCHY FOG
REDUCING VISIBILITIES FROM 3 TO 5SM...INCLUDING TAF SITES KSBY AND
KECG. A COLD FRONT APPROACHES THE REGION FROM THE NORTH AND STALLS
ACROSS THE AREA MONDAY AFTN. THE FRONT COUPLED WITH A WEAK SURFACE
TROUGH WILL INCREASE THUNDERSTORM CHANCES ACROSS THE AREA MON/MON
NIGHT. SE-S WINDS AOB 10 KT MON WILL VEER TO SW-W MON NIGHT. FOR
TUESDAY AND WEDNESDAY...THE FRONT REMAINS STATIONARY ACROSS THE
REGION AND CONTINUES A CHANCE FOR WIDESPREAD SHOWERS/STORMS. THE
LACK OF UPSTREAM FEATURES AND GENERALLY LIGHT STEERING FLOW ALOFT
(LESS THAN 25 KT) COULD LEAD TO MODERATE TO HEAVY RAINFALL IN
SLOW-MOVING STORMS...THUS REDUCING VIS/CIGS UNDER THE STRONGEST
STORM CORES. FOG WILL CONTINUE TO BE A POSSIBILITY OVERNIGHT AND
SHOULD GENERALLY FORM IN AREAS THAT RECEIVE RAINFALL DURING THE
AFTN/EVENING HOURS. DEVELOPING NW FLOW ALOFT WILL KEEP UNSETTLED
CONDITIONS ACROSS THE AREA THURSDAY AND FRIDAY.
&&
.MARINE...
UNSETTLED WEATHER PATTERN WILL PREVAIL OVER THE WATERS THRU THE
FORECAST PERIOD...BUT SCA CONDITIONS ARE NOT ANTICIPATED.
WEAK SFC TROUGH REMAINS OVER THE WATERS THIS AFTERNOON WITH WSW
WINDS AVG 5-10 KT AND WAVES/SEAS 1-2 FT. A COLD FRONT HAS DROPPED
INTO SRN PA LATE THIS AFTERNOON AS AN AREA OF LOW PRESSURE
PROPAGATES EWD OVER THE MID MS/LOWER OH VALLEY. THE FRONT WILL DROP
SWD TONIGHT OVER THE NRN WATERS AS HIGH PRESSURE BUILDS OVER NEW
ENGLAND. FLOW BECOMES NE ON THE BACKSIDE OF THE FRONT WITH WLY FLOW
TO THE SOUTH...REMAINING AOB 10 KT. SFC LOW WILL WEAKEN OVER THE
CNTRL APPALACHIANS AS A SECONDARY LOW DEVELOPS OVER THE WATERS. FLOW
WILL INCREASE SOUTH OF THE WATERS...BUT ANTICIPATE SPEEDS AROUND 10
KT TUES-TUES NIGHT. HIGH PRESSURE SLIDES OVER NEW ENGLAND
TUES...LOCATING OFFSHORE TUES NIGHT WEDS. MEANWHILE...LOW PRESSURE
REMAINS OVER THE WATERS. THE RESULT WILL BE PERIODS OF ONSHORE
FLOW...ESPECIALLY OVER THE NRN WATERS. NE FETCH WILL LIKELY PUSH
SEAS UPWARDS OF 3-4 FT...BUT NOT ANTICIPATING SCA CONDITIONS ATTM.
FRONTAL BOUNDARY REMAINS OVER THE REGION THRU THE WEEK...RESULTING
IN AN UNSETTLED WX PATTERN...BUT SUB-SCA CONDITIONS.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TMG
NEAR TERM...TMG/JAO
SHORT TERM...TMG
LONG TERM...SAM
AVIATION...BMD
MARINE...SAM
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
743 PM EDT TUE AUG 19 2014
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 422 PM EDT TUE AUG 19 2014
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW FROM WRN
LAKE SUPERIOR INTO W UPPER MI. A SHORTWAVE NEAR THE LOW CENTER
SUPPORTED AN AREA OF SHOWERS...SOME LOCALLY HEAVY...THROUGH CNTRL
UPPER MI. WITH THE SLOW FORWARD MOVEMENT...PWAT AROUND 1.5
INCHES...AND EFFICIENT WARM RAIN PROCESSES...NEARLY 2.0 INCHES OF
RAIN FELL AT THE NWS OFFICE BTWN 1915Z-1945Z. AN FLS WAS ISSUED TO
HIGHLIGHT THREAT FOR MINOR FLOODING WITH SMALL STREAMS AND LOW-LYING
AREAS. AT THE SFC...LOW PRES WAS LOCATED OVER NW UPPER MI.
EXPECT THE VERTICALLY STACKED LOW TO ONLY SLOWLY WOBBLE TO THE EAST
TO CNTRL/EAST UPPER MI BY 12Z/WED AND TO NEAR THE STRAITS BY 00Z/THU.
THERE WILL BE A CONTINUED THREAT FOR SOME LOCALLY HEAVY RAIN WITH
THE SHRTWV MOVING THROUGH CNTRL UPPER MI THIS EVENING.
ONLY ISOLD TSRA ARE EXPECTED...GIVEN AFTERNOON TRENDS AND MUCAPE BLO
1K J/KG.
OTHERWISE...HIGH RES MODELS AND UPSTREAM RADAR TRENDS SUGGEST RAIN
WILL BECOME MORE SCATTERED THIS EVENING AND DIMINISH FURTHER
OVERNIGHT. WITH ABUNDANT DEEP MOISTURE REMAINING OVER THE REGION
THROUGH WED MORNING...SOME SCT LIGHT SHOWERS OR DRIZZLE WILL REMAIN
POSSIBLE THROUGH THE MORNING...ESPECIALLY OVER THE N CNTRL AND EAST
EVEN WITH WEAK FORCING NEAR THE LOW. HOWEVER...ANY ADDITIONAL
RAINFALL AMOUNTS SHOULD BE LIGHT...LESS THAN A TENTH OF AN INCH.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 402 PM EDT TUE AUG 19 2014
THE UPPER LEVEL WAVE AND ASSOCIATED WEAK LOW PRESSURE SYSTEM THAT
ARE CURRENTLY OVER THE AREA WILL CONTINUE TO INFLUENCE THE UPPER
GREAT LAKES REGION INTO WEDNESDAY BEFORE PULLING OUT ON WEDNESDAY
NIGHT. AS THIS WAVE PULLS OUT...SHOULD SEE A DRY PERIOD OVER MUCH
OF THE U.P. FOR WEDNESDAY NIGHT INTO THURSDAY MORNING (ALTHOUGH
THERE COULD BE SOME LINGERING SHOWERS OVER THE NORTHEAST ON
WEDNESDAY EVENING) BEFORE THE NEXT WAVE ARRIVES THURSDAY AFTERNOON
AND REMAINS INTO FRIDAY. THE DRY PERIOD WILL BE AIDED BY THE WEAK
RIDGING ALOFT THAT WILL MOVE INTO THE UPPER GREAT LAKES REGION AND
ATTEMPT TO BUILD INTO THE GREAT LAKES REGION THROUGH THE WEEKEND.
AS THAT RIDGING OCCURS...AN UPPER TROUGH WILL ESTABLISH ITSELF
OVER THE NORTHERN ROCKIES AND EJECT OUT A COUPLE PIECES OF ENERGY
THROUGH THE REST OF THE EXTENDED PERIOD. THE FIRST WAVE WILL
MOVE INTO THE NORTHERN PLAINS ON WEDNESDAY AND THEN SHIFT NORTHEAST
ACROSS THE MINNESOTA ARROWHEAD THURSDAY EVENING AND INTO ONTARIO ON
FRIDAY. THERE ARE STILL SOME MODEL DIFFERENCES WITH HOW PROGRESSIVE
THIS SHORTWAVE AND ASSOCIATED WEAK LOW (AND WARM FRONT) ARE...AND IT
IS LARGELY TIED INTO THE STRENGTH OF THE SHORTWAVE. AT THIS
POINT...THE 12Z GFS APPEARS TO BE THE OUTLIER (KEEPS THE WARM FRONT
SOUTH OF THE CWA DUE TO WEAKER SHORTWAVE UNTIL THE NEXT WAVE
ARRIVES ON SATURDAY) WHILE THE 00Z ECMWF AND ITS ENSEMBLE
MEMBERS...ALONG WITH THE 12Z GEM/NAM...BRING THE WARM FRONT INTO THE
AREA LATE THURSDAY AFTERNOON AND PUSHING NORTHEAST OF THE AREA ON
FRIDAY NIGHT INTO SATURDAY. THINK THE NON GFS CONSENSUS IS THE WAY
TO GO AT THIS POINT AND FOLLOWS THE GENERAL IDEA FROM THE PREVIOUS
SHIFT. THEREFORE...WILL INCREASE PRECIP CHANCES FROM SOUTHWEST TO
NORTHEAST THURSDAY AFTERNOON INTO THURSDAY NIGHT AND THEN KEEP
CHANCE POPS INTO THE FIRST PART OF THE WEEKEND. WILL NEED TO KEEP
AN EYE ON CONVECTION FIRING IN EAST CENTRAL MINNESOTA AND NORTHWEST
WISCONSIN THURSDAY AFTERNOON ALONG THE WARM FRONT AND LOW LEVEL
MOISTURE TRANSPORT MAXIMUM IS LOCATED. COULD SEE SOME STRONG TO
POTENTIAL SEVERE STORMS IN THAT AREA...WHICH BASED OFF STORM MOTION
VECTORS WOULD TRY TO LIFT THEM EAST-NORTHEAST ALONG WITH THE FRONT
WHILE BUILDING TO THE SOUTHEAST. FAR WESTERN UPPER MICHIGAN WOULD
HAVE THE BEST OPPORTUNITY FOR SEEING THESE STRONGER STORMS HEADING
INTO THE EVENING HOURS.
ONCE THAT WAVE DECAYS AND SLIDES NORTHEAST OF THE
CWA...PRECIPITATION CHANCES WILL DEPEND ON OTHER WAVES EJECTING OUT
OF THE UPPER TROUGH OVER THE NORTHERN ROCKIES. RIDGE AXIS WILL BE
RIGHT OVER THE U.P. THROUGH SUNDAY AND THEN SHIFT EAST FOR THE
BEGINNING OF NEXT WEEK AS THE UPPER TROUGH GRADUALLY SHIFTS EAST.
WITH THAT RIDGE AXIS...IT APPEARS THAT SUNDAY WILL BE THE BEST
OPPORTUNITY FOR DRIER WEATHER BEFORE THE NEXT WAVE SLIDES NORTHEAST
OVER THE WESTERN HALF OF THE CWA SUNDAY NIGHT INTO MONDAY MORNING.
EXPECT IT TO BE FAIRLY MUGGY OVER THE AREA FRIDAY INTO THE
WEEKEND....ESPECIALLY WHEN COMPARED TO WHAT HAS BEEN SEEN IN THIS
REGION FOR MUCH OF THE SUMMER. AFTER THE NORMAL TO SLIGHTLY ABOVE
NORMAL TEMPERATURES VALUES THURSDAY THROUGH SUNDAY...THEY ARE
EXPECTED TO FALL BACK BELOW NORMAL FOR MONDAY AND TUESDAY BEHIND THE
COLD FRONT ASSOCIATED WITH THE WAVE THAT MOVES THROUGH ON SUNDAY
NIGHT.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 742 PM EDT TUE AUG 19 2014
LOW PRES SYSTEM OVER THE UPPER GREAT LAKES WILL VERY SLOWLY DRIFT
ESE OVER THE NEXT 24HRS. ABUNDANT LOW-LEVEL MOISTURE ASSOCIATED WITH
SYSTEM WILL RESULT IN LIFR TO POSSIBLY OCNL VLIFR CONDITIONS AT
KIWD/KCMX/KSAW THRU AT LEAST MID MORNING WED. -SHRA/-DZ ARE ALSO
EXPECTED AT TIMES...ESPECIALLY AT KCMX/KSAW. GRADUAL IMPROVEMENT
SHOULD OCCUR WED AFTN...THOUGH ONLY KIWD MAY REACH VFR BY THE LATTER
PART OF THE AFTN.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 422 PM EDT TUE AUG 19 2014
SOME FOG IS EXPECTED TO PERSIST OVER THE CNTRL AND ERN LAKE TONIGHT
GIVEN ABUNDANT LOW LEVEL MOISTURE AND LIGHT WINDS. EXPECT WINDS
UNDER 20 KTS THROUGH SATURDAY AS A RELATIVELY WEAK PRESSURE GRADIENT
DOMINATES THE UPPER GREAT LAKES ABOVE THE RELATIVELY COLD WATERS OF
LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...ROLFSON
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
432 PM EDT MON AUG 18 2014
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 322 PM EDT MON AUG 18 2014
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A FAIRLY STRONG
SHRTWV OVER THE NRN PLAINS DRIFTING TO THE ESE INTO NW MN DOWNSTREAM
OF A RDG OVER WRN CANADA AND TOWARD A SHRTWV RDG STRETCHING FM
HUDSON BAY TOWARD THE SE GREAT LKS ON THE WRN FLANK OF A DEEP TROF
OVER THE CNDN MARITIMES. THERE IS ALSO A WEAKER SHRTWV MOVING E THRU
THE UPR LKS AHEAD OF THE MAIN DISTURBANCE APRCHG MN...AND THIS
FEATURE ALONG WITH ACCOMPANING AXIS OF GREATER H85 THETA E ADVCTN/A
FAIRLY MOIST 12Z GRB RAOB /KINX 36C AND PWAT 1.64 INCH OR ALMOST 175
PERCENT OF NORMAL/ HAS BEEN THE FOCUS FOR SOME SCT-NMRS SHOWERS
MAINLY OVER CENTRAL CWA TODAY. BUT QUITE A CONTRAST JUST TO THE E
WITH THE 12Z APX RAOB DISPLAYING A MUCH DRIER PROFILE...KINX -12C
AND PWAT 0.66 INCH OR ONLY 75 PERCENT OF NORMAL. THIS DRIER/STABLE
AIRMASS HAS SLOWED THE PROGRESS OF THE SHOWERS INTO THE AREA ARND
NEWBERRY SO FAR. THERE ARE MORE NMRS SHOWERS/A FEW TS MOVING INTO
WRN LK SUP CLOSER TO THE TRAILING SHRTWV. OTRW...QUITE A BIT OF CLD
COVER HAS LIMITED THE DIURNAL RISE OF TEMP AND DESTABILIZATION IN
THE ABSENCE OF STEEP LAPSE RATES SHOWN ON EVEN THE MOISTER 12Z GRB
RAOB...SO TS HAVE BEEN FEW AND FAR BTWN. BUT SOME HEAVY RAINS HAVE
FALLEN UNDER THE STRONGER SHOWERS WITH THE HIER PWAT/DEEPER MSTR.
MAIN FCST CONCERNS IN THE SHORT TERM ARE POPS RELATED TO THE TWO
DISTURBANCES THAT ARE MOVING THRU MN/THE UPR LKS.
LATE TODAY/TNGT...AS TROF OVER QUEBEC SLOWLY EXITS TO THE E...LEAD
SHRTWV MOVING THRU THE UPR LKS/ACCOMPANYING AXIS OF H85 THETA E
ADVCTN WL DRIFT TO THE E AND BRING SOME SHOWERS TO THE FAR ERN CWA
BY 00Z. ALTHOUGH THERE MAY BE ONLY SOME ISOLD/SCT SHOWERS OVER WRN
UPR MI WITH SOME H7-5 DRYING MOST OF TODAY...MORE NMRS SHOWERS/SOME
TS ASSOCIATED WITH THE STRONGER SHRTWV MOVING INTO MN WL ARRIVE OVER
THE FAR W ARND 00Z TOWARD AREA WHERE THE 12Z NAM/REGIONAL CNDN MODEL
SHOW HIER MUCAPE UP TO ABOUT 750 J/KG NEAR IWD. BUT SINCE THE MN
SHRTWV WL BE TENDING TO DIG ESEWD THRU THE NGT...THE 12Z NAM/
REGIONAL CNDN MODEL INDICATE THE MORE NMRS SHOWERS WL IMPACT WI
CLOSER TO MORE VIGOROUS H85-7 MSTR CNVGC/HIER MUCAPE IN THE 500-
1000J/KG THAT WL BE CONFINED TO WI. SO WL MAINTAIN THE HIEST LIKELY
POPS TOWARD THE WI BORDER... ALONG WITH THE TS CHANCES PER ABSENCE
OF FCST MUCAPE AOA 200 J/KG FARTHER N. BUT DEEP LYR QVECTOR CNVGC/
DEEP SATURATION ON FCST SDNGS ON THE CYC SIDE OF SHRTWV TRACK
JUSTIFIES AT LEAST 50-60 POPS OVER THE ENTIRE CWA EVEN IF THE BETTER
FORCING/INSTABILITY HOLD TO THE SW. EXPECT LTL DIURNAL TEMP DROP
WITH LOTS OF CLDS/LINGERING HIER PWAT IN THE 1.50-1.75 RANGE. ADDED
SOME PATCHY FOG...ESPECIALLY IN AREAS OVER THE CENTRAL THAT WL
EXPERIENCE UPSLOPE SE FLOW.
TUE...EXPECT CONTINUED SCT-NMRS SHOWERS AND A FEW TS AS THE SHRTWV/
SFC LO REFLECTION SLIDE ESEWD THRU NRN WI AND MAINTAINS DEEP MSTR...
CYC FLOW AND DEEP LYR QVECTOR CNVGC OVER UPR MI. FCST WL SHOW
DIMINISHING POPS IN THE AFTN OVER THE W WITH PASSAGE OF SHRTWV TO
THE E AND ARRIVAL OF SOME DNVA/DEEP LYR QVECTOR DVGC AFT 18Z. FOG IN
THE MRNG OVER MAINLY THE CENTRAL ZNS WL DSPT SLOWLY WITH DIURNAL
HEATING LIMITED BY EXTENSIVE CLD COVER.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 431 PM EDT MON AUG 18 2014
THE 500MB LOW CENTERED OVER UPPER MI AND LAKE SUPERIOR AT 00Z
WEDNESDAY WILL SHIFT ACROSS LAKE HURON WEDNESDAY NIGHT/THURSDAY
MORNING WITH A BRIEF RIDGE BUILDING ACROSS UPPER MI THURSDAY. THE
APEX OF THE RIDGE WILL SHIFT JUST TO OUR E THURSDAY NIGHT. A SIZABLE
TROUGH SET UP FROM FROM W AND CENTRAL CANADA THROUGH THE ENTIRE W
U.S. WEDNESDAY WILL SLOWLY SHIFT THE N CENTRAL U.S. FOR THE
WEEKEND...AND UPPER GREAT LAKES SUNDAY NIGHT/MONDAY.
AS FOR THE SFC FEATURES AND WX...THE EXITING SFC LOW OVER N LAKE MI
AT 00Z WEDNESDAY WILL LINGER THROUGH THE NIGHT BEFORE SHIFTING TO
LOWER MI THROUGH THE DAY WEDNESDAY. WITH WRAP AROUND/UPSLOPE
MOISTURE ACROSS THE AREA...EXPECT LIGHT SHOWERS TO LINGER THROUGH
MID DAY AT LEAST. THE BEST CHANCE OF THUNDERSTORMS WILL SINK SE WITH
THE SFC LOW.
IT LOOKS LIKE THE ONLY PERIOD OF MAINLY DRY WEATHER WILL BE LATE
WEDNESDAY AFTERNOON THROUGH THURSDAY MORNING...DESPITE THE 500MB
RIDGE OVERHEAD THURSDAY THROUGH FRIDAY. THE LARGE HIGH PRESSURE OVER
QUEBEC...WITH A RIDGE EXTENDING OVER THE UPPER GREAT LAKES WILL EXIT
E ON FRIDAY. THERE STILL LOOKS TO BE PLENTY OF INCONSISTENCIES FOR
FRIDAY AFTERNOON ON. WILL CONTINUE TO RUN WITH A GENERAL CONSENSUS
FOR THIS PERIOD...WITH HAS AN ELONGATED SFC LOW FROM HUDSON BAY
THROUGH MN AND THE CENTRAL PLAINS AT 00Z SUNDAY. THE LOW WILL SLOWLY
SHIFT TO ONTARIO/FAR W LAKE SUPERIOR SATURDAY. THIS WOULD BRING WAA
TO THE AREA WITH HIGH TEMPS RETURNING TO NEAR NORMAL READINGS FRIDAY
AND SATURDAY. THE SFC TROUGH SHOULD BE OVER THE CWA SATURDAY
NIGHT/SUNDAY MORNING. HAVE SLOWLY DIMINISHING POPS FOR SUNDAY AND
MONDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 123 PM EDT MON AUG 18 2014
ALTHOUGH THE SPECIFICS ARE FAR FROM CLEAR...EXPECT IFR CONDITIONS TO
PREDOMINATE THIS FCST PERIOD WITH DEEP MSTR/SCT TO AT TIMES NMRS
SHRA OVER THE UPR LKS ASSOCIATED WITH DISTURBANCE MOVING SLOWLY
ESEWD THRU MN. BEST CHC FOR THE LOWER LIFR...AND POSSIBLY VLIFR...
CONDITIONS WL BE LATER TNGT/EARLY TUE IN THE PRESENCE OF NOCTURNAL
COOLING WHEN THE TAF SITES EXPERIENCE UPSLOPE FLOW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 322 PM EDT MON AUG 18 2014
ADDED SOME FOG TO THE FORECAST THRU MUCH OF TUE OVER MAINLY THE
CENTRAL LAKE GIVEN ARRIVAL OF DEEPER MOISTURE AND EXPECTED AREA OF
LOWER TEMPERATURES NEAR THE LINGERING COOLEST DEEPER WATER.
OTHERWISE... EXPECT WINDS UNDER 20 KTS OVER THE NEXT WEEK AS A
RELATIVELY WEAK PRESSURE GRADIENT DOMINATES THE UPPER GREAT LAKES
ABOVE THE CHILLY WATERS OF LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KF
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
345 PM EDT MON AUG 18 2014
LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/HYDRO/MARINE
.SYNOPSIS...
ISSUED AT 345 PM EDT MON AUG 18 2014
THE REGION IS HEADING INTO A WETTER PATTERN THE NEXT WEEK WITH THE
FIRST CHANCES FOR RAINFALL COMING UP TONIGHT INTO TUESDAY. ANOTHER
TIME FRAME OF PERIODS OF SHOWERS AND STORMS WILL COME FROM THURSDAY
THROUGH SUNDAY WITH A FRONTAL BOUNDARY NEAR THE AREA. SHOWERS AND
STORMS WILL BECOME MORE NUMEROUS LATE TONIGHT AND ESPECIALLY ON
TUESDAY AS AN AREA OF LOW PRESSURE MOVES INTO THE GREAT LAKES. A
GRADUAL WARMING TREND WILL BE SEEN THROUGH THE WEEK AND INTO NEXT
WEEKEND. HIGHS AROUND 80 AT THE START OF THE WEEK WILL WARM TO THE
MIDDLE 80S BY NEXT WEEKEND.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 345 PM EDT MON AUG 18 2014
MAIN FOCUS IN THE SHORT TERM IS ON THE CHANCES FOR SHOWERS/STORMS
TONIGHT INTO TUESDAY. PRECIPITATION WILL BE DRIVEN BY AN TROUGH
DIGGING INTO THE GREAT LAKES REGION FROM THE NORTHERN PLAINS.
MOISTURE SURGES INTO REGION THIS EVENING WITH THE HRRR TRYING TO
FLOAT CONVECTION FROM WISCONSIN OVER LAKE MICHIGAN IN THE 00Z-06Z
TIME FRAME. THINKING OUR BEST CHANCES FOR PRECIP THOUGH WILL BE
OVERNIGHT INTO TUESDAY WHEN ALL OF THE SHORT TERM MODELS FOCUS A LLJ
ON THE AREA. NOT EXPECTING SEVERE WEATHER GIVEN THE TIMING OF THE
PRECIP AND THE FACT THAT INSTABILITY WILL LIKELY BE LIMITED SOMEWHAT
BY OVERNIGHT PRECIP. 0-6KM SHEAR IS SUB 30 KNOTS BOTH TONIGHT AND
TUESDAY FOR THE MOST PART AS WELL. SOME LOCALLY HEAVY RAIN IS
POSSIBLE.
SHOWERS AND STORMS WILL BECOME MORE SCATTERED TUESDAY NIGHT THROUGH
WEDNESDAY AS THE SYSTEM FILLS OVERHEAD. PLENTY OF MOISTURE LINGERS
HOWEVER SO SCATTERED SHOWERS AND A FEW STORMS WILL REMAIN POSSIBLE
BOTH PERIODS. WEDNESDAY NIGHT KEPT THE DRY FORECAST GOING AS SURFACE
RIDGING BEGINS TO TAKE OVER AND THE UPPER LOW SLIDES SLIGHTLY OFF TO
THE EAST.
.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 345 PM EDT MON AUG 18 2014
IT LOOKS TO BE A RATHER ACTIVE EXTENDED PERIOD. THE MAIN FOCUS WILL
BE ON OPPORTUNITIES FOR SHOWERS AND STORMS THURSDAY THROUGH SUNDAY
NIGHT. BY 12Z THURSDAY...A ULJ CORE WILL BE MOVING ACROSS THE LOWER
PENINSULA AS UPPER LEVEL RIDGING BUILDINGS IN. IN CONCERT WITH THIS
WILL BE A FAIRLY STRONG H850 TEMP GRADIENT (6-8C) MOVING INTO SW
LOWER MICHIGAN AND INCREASING MID LEVEL MOISTURE. LIGHT EASTERLY
WIND CONV AT THE SFC (AS SHOWN BY THE ECMWF) MAY HELP ENHANCE
CONVECTIVE DEVELOPMENT PARTICULARLY ACROSS THE LAKESHORE REGION AND
GENERALLY ALONG AND WEST OF US 131 FOR THURSDAY EVENING INTO FRIDAY.
WHILE MODEL QPF IS NOT HIGH...INCREASING PW VALUES TO 2" OR SO ON
FRIDAY IS A CAUSE FOR CONCERN WITH ANY STORMS THAT DO DEVELOP.
LOCALLY HEAVY DOWNPOURS WOULD BE A POSSIBILITY THURSDAY NIGHT AND
FRIDAY ON THE WING OF WARM AIR ADVECTION. IF H500 HEIGHTS CONTINUE
TO BUILD STRONG ENOUGH BY SATURDAY (LIKE THE ECMWF SHOWS) THEN
PERHAPS WE WILL BE STABLE ENOUGH TO MITIGATE ANY SIGNIFICANT
CONVECTION. ON SATURDAY...GFS BUFKIT SOUNDINGS INDICATE SIGNIFICANT
SFC BASED CAPE UPWARDS OF 2000 J/KG AND LI VALUES OF -4 TO -6 BUT
WEAK SHEAR AND WEAK MID LEVEL LAPSE RATES. ECMWF WOULD SUGGEST A
LACK OF TRIGGER AND MORE STABLE CONDITIONS. OUR POP GRIDS ARE
CURRENTLY MIDDLE OF THE ROAD CHC CATEGORY FOR SATURDAY...REFLECTING
A LACK OF MODEL BULLISHNESS ON PRECIP.
UPPER LEVEL RIDGING MAY FLATTEN LATER SUNDAY AND AN ASSOCIATED
COLD FRONT COULD ARRIVE BY SUNDAY NIGHT. THE TIMING OF THIS IS
ACTUALLY AGREED UPON BY THE GFS AND ECMWF (00Z-06Z MON)...WHEREAS
THE GEM CLEARS THE FRONT 24 HOURS EARLIER. CURRENTLY AM PREFERRING A
SLOWER BREAKDOWN OF THE H500 RIDGE AND THUS A SLOWER FROPA AS SHOWN
BY THE GFS AND ECMWF. THERE WILL LIKELY BE SUFFICIENT DEEP LAYER
SHEAR BY THAT TIME TO PROVIDE A MORE CONDUCIVE ENVIRONMENT TO
STRONGER STORMS.
IN TERMS OF TEMPS AND HUMIDITY...BOTH WILL BE GOING UP BY THE
WEEKEND. DEW POINTS SHOULD CLIMB TO AROUND 70 AND HIGHS IN THE MID
80S MAY BE CONSERVATIVE FOR SATURDAY AND SUNDAY DEPENDING ON MUCH
CLOUD COVER HANGS AROUND. WOULDN`T BE SURPRISED IF HIGHS NOTCH UP
SEVERAL DEGREES WARMER WITH H850 TEMPS OF 20C KNOCKING ON THE DOOR
SATURDAY EVENING. COOLER WEATHER MOVES IN FOR EARLY NEXT WEEK BEHIND
THE FRONT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 139 PM EDT MON AUG 18 2014
THE TREND WILL BE FOR LOWERING CIGS IN THE 12Z-15Z TIME FRAME
POSSIBLY CLOSE TO IFR AS RA AND TSRA DEVELOPS AHEAD OF A FRONT IN
WISCONSIN TUESDAY. MODEL GUIDANCE IS NOT INDICATING IFR BUT
UPSTREAM OBSERVATIONS WHERE IT HAS RAINED IN WISCONSIN SUGGEST IFR
IS A DISTINCT POSSIBILITY...IN TERMS OF CIGS. HAVE THEREFORE
TRENDING CIGS TOWARD BUT NOT IN IFR FOR ALL SITES AS THE RA AND
TSRA MOVES IN DURING THE MORNING AND AFTERNOON HOURS. VISIBILITIES
SHOULD COME DOWN SOME BUT NOT IFR. CONDITIONS WILL LIKELY NOT
IMPROVE UNTIL AFTER 18Z FOR MKG AND POSSIBLY GRR AND AZO...AND A
FAIR AMOUNT LATER FOR LAN AND JXN.
&&
.MARINE...
ISSUED AT 345 PM EDT MON AUG 18 2014
MAIN IMPACT WEATHER FOR WINDS/WAVES WILL COME ON TUESDAY. SOUTH
WINDS WILL INCREASE TONIGHT INTO TUESDAY WITH WAVES BECOMING
BORDERLINE FOR BEACH HAZARDS FROM HOLLAND NORTHWARD UP THE SHORE.
EXPECTING WAVES TO PUSH INTO THE 2 TO 4 FOOT RANGE ON TUESDAY NORTH
OF HOLLAND OR SO. THE WINDS SLACKEN OFF AS WE HEAD INTO WEDNESDAY AS
THE GRADIENT BECOMES BAGGY...SO THE WAVES WILL SUBSIDE FOR MID WEEK.
&&
.HYDROLOGY...
ISSUED AT 139 PM EDT MON AUG 18 2014
RIVERS ARE RUNNING A LITTLE ABOVE NORMAL... BUT ARE STILL FAR BELOW
BANK FULL. PRECIPITATION THIS EVENING THROUGH WEDNESDAY IS EXPECTED
TO TOTAL AROUND HALF AN INCH. THIS SHOULD LEAD TO SLOW RISES ON AREA
RIVERS WITH PEAK LEVELS WELL BELOW FLOOD STAGE OCCURRING BY THE END
OF THE WEEK. LOCALLY HEAVY RAINFALL IS POSSIBLE AND COULD LEAD TO
BRIEFLY HIGHER FLOWS.
LOOKING AHEAD...IT APPEARS TO BE A RATHER ACTIVE SECOND HALF OF
AUGUST WHICH MAY HELP BRING MANY RIVERS TO ABOVE NORMAL FLOWS.
WITH AN UPPER LEVEL RIDGE DEVELOPING TO THE SOUTH OF THE GREAT
LAKES OVER THE NEXT WEEK OR SO...IT WILL PLACE MICHIGAN IN AN
ACTIVE WEATHER PATTERN WITH NUMEROUS OPPORTUNITIES FOR RAIN.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...HOVING
AVIATION...HOVING
HYDROLOGY...63
MARINE...DUKE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
324 PM EDT MON AUG 18 2014
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 322 PM EDT MON AUG 18 2014
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A FAIRLY STRONG
SHRTWV OVER THE NRN PLAINS DRIFTING TO THE ESE INTO NW MN DOWNSTREAM
OF A RDG OVER WRN CANADA AND TOWARD A SHRTWV RDG STRETCHING FM
HUDSON BAY TOWARD THE SE GREAT LKS ON THE WRN FLANK OF A DEEP TROF
OVER THE CNDN MARITIMES. THERE IS ALSO A WEAKER SHRTWV MOVING E THRU
THE UPR LKS AHEAD OF THE MAIN DISTURBANCE APRCHG MN...AND THIS
FEATURE ALONG WITH ACCOMPANING AXIS OF GREATER H85 THETA E ADVCTN/A
FAIRLY MOIST 12Z GRB RAOB /KINX 36C AND PWAT 1.64 INCH OR ALMOST 175
PERCENT OF NORMAL/ HAS BEEN THE FOCUS FOR SOME SCT-NMRS SHOWERS
MAINLY OVER CENTRAL CWA TODAY. BUT QUITE A CONTRAST JUST TO THE E
WITH THE 12Z APX RAOB DISPLAYING A MUCH DRIER PROFILE...KINX -12C
AND PWAT 0.66 INCH OR ONLY 75 PERCENT OF NORMAL. THIS DRIER/STABLE
AIRMASS HAS SLOWED THE PROGRESS OF THE SHOWERS INTO THE AREA ARND
NEWBERRY SO FAR. THERE ARE MORE NMRS SHOWERS/A FEW TS MOVING INTO
WRN LK SUP CLOSER TO THE TRAILING SHRTWV. OTRW...QUITE A BIT OF CLD
COVER HAS LIMITED THE DIURNAL RISE OF TEMP AND DESTABILIZATION IN
THE ABSENCE OF STEEP LAPSE RATES SHOWN ON EVEN THE MOISTER 12Z GRB
RAOB...SO TS HAVE BEEN FEW AND FAR BTWN. BUT SOME HEAVY RAINS HAVE
FALLEN UNDER THE STRONGER SHOWERS WITH THE HIER PWAT/DEEPER MSTR.
MAIN FCST CONCERNS IN THE SHORT TERM ARE POPS RELATED TO THE TWO
DISTURBANCES THAT ARE MOVING THRU MN/THE UPR LKS.
LATE TODAY/TNGT...AS TROF OVER QUEBEC SLOWLY EXITS TO THE E...LEAD
SHRTWV MOVING THRU THE UPR LKS/ACCOMPANYING AXIS OF H85 THETA E
ADVCTN WL DRIFT TO THE E AND BRING SOME SHOWERS TO THE FAR ERN CWA
BY 00Z. ALTHOUGH THERE MAY BE ONLY SOME ISOLD/SCT SHOWERS OVER WRN
UPR MI WITH SOME H7-5 DRYING MOST OF TODAY...MORE NMRS SHOWERS/SOME
TS ASSOCIATED WITH THE STRONGER SHRTWV MOVING INTO MN WL ARRIVE OVER
THE FAR W ARND 00Z TOWARD AREA WHERE THE 12Z NAM/REGIONAL CNDN MODEL
SHOW HIER MUCAPE UP TO ABOUT 750 J/KG NEAR IWD. BUT SINCE THE MN
SHRTWV WL BE TENDING TO DIG ESEWD THRU THE NGT...THE 12Z NAM/
REGIONAL CNDN MODEL INDICATE THE MORE NMRS SHOWERS WL IMPACT WI
CLOSER TO MORE VIGOROUS H85-7 MSTR CNVGC/HIER MUCAPE IN THE 500-
1000J/KG THAT WL BE CONFINED TO WI. SO WL MAINTAIN THE HIEST LIKELY
POPS TOWARD THE WI BORDER... ALONG WITH THE TS CHANCES PER ABSENCE
OF FCST MUCAPE AOA 200 J/KG FARTHER N. BUT DEEP LYR QVECTOR CNVGC/
DEEP SATURATION ON FCST SDNGS ON THE CYC SIDE OF SHRTWV TRACK
JUSTIFIES AT LEAST 50-60 POPS OVER THE ENTIRE CWA EVEN IF THE BETTER
FORCING/INSTABILITY HOLD TO THE SW. EXPECT LTL DIURNAL TEMP DROP
WITH LOTS OF CLDS/LINGERING HIER PWAT IN THE 1.50-1.75 RANGE. ADDED
SOME PATCHY FOG...ESPECIALLY IN AREAS OVER THE CENTRAL THAT WL
EXPERIENCE UPSLOPE SE FLOW.
TUE...EXPECT CONTINUED SCT-NMRS SHOWERS AND A FEW TS AS THE SHRTWV/
SFC LO REFLECTION SLIDE ESEWD THRU NRN WI AND MAINTAINS DEEP MSTR...
CYC FLOW AND DEEP LYR QVECTOR CNVGC OVER UPR MI. FCST WL SHOW
DIMINISHING POPS IN THE AFTN OVER THE W WITH PASSAGE OF SHRTWV TO
THE E AND ARRIVAL OF SOME DNVA/DEEP LYR QVECTOR DVGC AFT 18Z. FOG IN
THE MRNG OVER MAINLY THE CENTRAL ZNS WL DSPT SLOWLY WITH DIURNAL
HEATING LIMITED BY EXTENSIVE CLD COVER.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 326 AM EDT MON AUG 18 2014
THE START OF THE PERIOD WILL BE A WET ONE AS AN UPPER WAVE OVER WRN
LAKE SUPERIOR AT 12Z TUE CLOSES OFF AS IT MOVES INTO THE WRN U.P. BY
18Z TUE. THE UPPER LOW WILL THEN SLOW DOWN...FINALLY LEAVING THE
AREA LATER ON WED. THE SFC LOW WILL BE SOMEWHERE OVER NRN WI OR
ALONG THE WI/MI BORDER AT 12Z TUE AND WILL SLOWLY SHIFT E INTO TUE
NIGHT BEFORE MORE QUICKLY MOVING SE ON WED. PWATS ON TUE WILL BE
BETWEEN 1.5 AND 1.7 INCHES /NORMAL IS AROUND AN INCH/...WHICH WHEN
COMBINED WITH THE FORCING FROM THE UPPER LOW/CYCLONIC FLOW AND
UPSLOPE FLOW OFF THE GREAT LAKES IN SPOTS /ESPECIALLY OVER WRN UPPER
MI/...WILL RESULT IN DECENT PRECIPITATION PRODUCTION. THINK THAT
SOME SPOTS COULD SEE EASILY OVER AN INCH OF PRECIP ON TUE/EARLY TUE
NIGHT...DEPENDING ON SMALLER SCALE FEATURES THAT ARE NOT ENTIRELY
CLEAR AT THIS POINT. WHILE IT IS HARD TO GET TOO SPECIFIC ON
HEAVIEST PRECIP PLACEMENT/TIMING...THINK THAT MOST OF THE CWA WILL
SEE PERIODS OF RAIN TUE INTO TUE NIGHT...SO WILL INCREASE POPS TO
LIKELY IN MOST PLACES. WILL LEAVE THUNDER CHANCES TO A MINIMUM...BUT
WILL HAVE A CHANCE OF THUNDER OVER SCENTRAL AND WRN UPPER MI WHERE
CAPES WILL BE A BIT HIGHER AT AROUND 200J/KG DURING THE DAY TUE.
WITH THICK CLOUD COVER...MAX TEMPS ON TUE WILL BE IN THE MID 60S TO
LOW 70S...OR 5 TO POSSIBLY 10 DEGREES BELOW NORMAL.
WED WILL SEE DECREASING PRECIP CHANCES AS THE SYSTEM MOVES SE...BUT
DO LINGER CHANCE POPS THROUGH THE MORNING. BEHIND THE SYSTEM...AN
UPPER RIDGE DEVELOPS OVER THE REGION...WHICH WILL KEEP THINGS A BIT
DRIER THAN EARLY IN THE WEEK. MODELS DO POINT TO PRECIPITATION
OCCURRING ALONG A WARM FRONT THAT MOVES THROUGH THU INTO THU
NIGHT...BUT IT IS UNCERTAIN HOW MUCH PRECIP WILL MAKE IT INTO THE
CWA AS THE FRONT MOVES UNDER THE UPPER RIDGE AND INTO THE DRIER AIR.
WILL HAVE CHANCE POPS THU INTO THU NIGHT...AND SOME LINGERING POPS
INTO FRI.
UNCERTAINTY IS GREATER GOING INTO THE WEEKEND AS MODELS SHOW QUITE A
BIT OF VARIABILITY /RUN TO RUN AND MODEL TO MODEL/ WITH THE
STRENGTH/TRACK/TIMING OF A LOW PRESSURE SYSTEM MOVING SOMEWHERE IN
OR NEAR THE REGION. WHILE MODELS DO APPEAR TO AGREE WITH QPF ON
SAT/SAT NIGHT...THEY DO NOT AGREE ON THE REASON FOR THAT QPF...SO
CONFIDENCE IS LOWER THAN IT WOULD SEEM BY JUST LOOKING AT QPF.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 123 PM EDT MON AUG 18 2014
ALTHOUGH THE SPECIFICS ARE FAR FROM CLEAR...EXPECT IFR CONDITIONS TO
PREDOMINATE THIS FCST PERIOD WITH DEEP MSTR/SCT TO AT TIMES NMRS
SHRA OVER THE UPR LKS ASSOCIATED WITH DISTURBANCE MOVING SLOWLY
ESEWD THRU MN. BEST CHC FOR THE LOWER LIFR...AND POSSIBLY VLIFR...
CONDITIONS WL BE LATER TNGT/EARLY TUE IN THE PRESENCE OF NOCTURNAL
COOLING WHEN THE TAF SITES EXPERIENCE UPSLOPE FLOW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 322 PM EDT MON AUG 18 2014
ADDED SOME FOG TO THE FORECAST THRU MUCH OF TUE OVER MAINLY THE
CENTRAL LAKE GIVEN ARRIVAL OF DEEPER MOISTURE AND EXPECTED AREA OF
LOWER TEMPERATURES NEAR THE LINGERING COOLEST DEEPER WATER.
OTHERWISE... EXPECT WINDS UNDER 20 KTS OVER THE NEXT WEEK AS A
RELATIVELY WEAK PRESSURE GRADIENT DOMINATES THE UPPER GREAT LAKES
ABOVE THE CHILLY WATERS OF LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
327 AM EDT MON AUG 18 2014
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 332 PM EDT SUN AUG 17 2014
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A NW FLOW ALF BTWN
A SLOWLY RETREATING...DEEP UPR TROF IN QUEBEC AND AN UPR RDG IN THE
PLAINS/UPR MS RIVER VALLEY. SFC HI PRES UNDER THIS RDG AXIS IS
LOCATED JUST NNW OF LK SUP. THE LLVL NE FLOW ON THE SRN FLANK OF
THIS HI IS FUNNELING SOME COOL...MOIST AIR INTO THE UPR LKS BLO
SHARP SUBSIDENCE INVRN ARND H85 AS SHOWN ON THE LOCAL 12Z RAOBS. THE
RESULT HAS BEEN A GOOD DEAL OF LO CLD COVER. THERE WAS EVEN SOME
DRIZZLE INTO THE EARLY AFTN OVER THE HIER TERRAIN OF THE NCENTRAL...
WHERE THE NE WIND PRESENTS A SHARPER UPSLOPE COMPONENT. BUT WITH
DAYTIME HEATING UNDER THE MID LVL DRY AIR AND SOME DRY H95-9
ADVECTION FM THE NE...THE LO CLDS ARE SHOWING SIGNS OF BREAKING
UP...ESPECIALLY IN AREAS THAT EXPERIENCE DOWNSLOPE FLOW. LOOKING TO
THE W...A VIGOROUS SHRTWV IN SRN SASKATCHEWAN IS MOVING EWD JUST N
OF THE CNDN BORDER AND TENDING TO SUPPRESS THE UPR RDG IN THE
PLAINS. THERE IS ANOTHER WEAKER SHRTWV AHEAD OF THIS FEATURE MOVING
THRU MN. CLDS ALONG WITH SHOWERS/A FEW TS ASSOCIATED WITH THIS
DISTURBANCE/OVERALL H85 THETA E ADVCTN IN THE LARGER SCALE SW FLOW
AHEAD OF THE STRONGER SASKATCHEWAN SHRTWV ARE APRCHG DULUTH EARLY
THIS AFTN.
MAIN FCST CONCERNS INTO THIS EVNG ARE FOCUSED ON LO CLD TRENDS.
TIMING/COVERAGE OF SHOWERS ASSOCIATED WITH PAIR OF UPSTREAM SHRTWVS
ARE THE CONCERNS FOR LATER TNGT AND MON.
LATE TODAY/TNGT...ALTHOUGH THE COMBINATION OF SOME LLVL DRY ADVCTN
AND DAYTIME HEATING MAY BREAK UP THE LO CLDS NOW IMPACTING THE CWA
THRU THIS AFTN...FAIRLY HI INVRN BASE OBSVD ON THE 12Z RAOBS WL
PROBABLY MAINTAIN BKN LO CLDS AT MANY LOCATIONS NOT IMPACTED BY
DOWNSLOPING FLOW AS THE SLOWLY RISING LCL WL REMAIN UNDER THE HIER
INVRN BASE. BUT THE LATEST TRENDS INDICATE THESE CLDS SHOULD BE
ALMOST COMPLETELY GONE BY 00Z. AFTER THIS EVNG...CLD COVER/SCT
SHOWERS NOW APRCHG DLH ARE LIKELY TO SPREAD INTO THE WRN CWA IN
ADVANCE OF LEAD SHRTWV AND WHERE STRONGER H85 THETA E ADVCTN WL
DVLP. EXPECT THE LOWEST MIN TEMPS OVER THE INTERIOR E WHERE THERE IS
LIKELY TO BE A LONGER PERIOD OF MOCLR SKIES/LGT WINDS CLOSER TO SFC
HI MOVING FM ERN LK SUP INTO ADJOINING ONTARIO. ADDED SOME PATCHY
FOG TO THE FCST IN THIS AREA WHERE TEMPS ARE EXPECTED TO FALL BLO
THE CROSS OVER DEWPTS OBSVD THIS AFTN.
MON...MAIN SHRTWV NOW MOVING THRU SRN SASKATCHEWAN IS FCST TO MOVE
INTO MN DURING THE AFTN. ALTHOUGH SOME SCT SHOWERS ASSOCIATED WITH
THE LEAD DISTURBANCE/AREA OF H85 THETA E ADVCTN MAY SPREAD INTO THE
CENTRAL AND ERN CWA...THESE ARE MORE LIKELY TO WEAKEN WITH TIME AS
THE CLUSTER MOVES TOWARD THE SHRTWV RDG AXIS/DRIER MID LVL AIR ON
THE WRN FLANK OF THE SLOW MOVING QUEBEC TROF. MORE NMRS SHOWERS ARE
LIKELY TO MOVE INTO THE W HALF OF THE CWA IN THE AFTN UPON THE
ARRIVAL OF DEEPER MSTR/MORE VIGOROUS DYANMIC SUPPORT ASSOCIATED WITH
THE MORE VIGOROUS TRAILING SHRTWV IN THE PRESENCE OF DAYTIME
HEATING. WITH FCST MUCAPES NO HIER THAN 100-200 J/KG ASSOCIATED WITH
A GOOD DEAL OF CLD COVER/EXPECTED DAYTIME HI TEMPS MAINLY IN THE
60S...WL LEAVE OUT A MENTION OF TS EXCEPT OVER THE FAR W...WHERE THE
MORE UNSTABLE GFS HINTS MUCAPES MAY REACH 500 J/KG CLOSER TO THE
INCOMING DISTURBANCE/COLDER AIR ALF.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 326 AM EDT MON AUG 18 2014
THE START OF THE PERIOD WILL BE A WET ONE AS AN UPPER WAVE OVER WRN
LAKE SUPERIOR AT 12Z TUE CLOSES OFF AS IT MOVES INTO THE WRN U.P. BY
18Z TUE. THE UPPER LOW WILL THEN SLOW DOWN...FINALLY LEAVING THE
AREA LATER ON WED. THE SFC LOW WILL BE SOMEWHERE OVER NRN WI OR
ALONG THE WI/MI BORDER AT 12Z TUE AND WILL SLOWLY SHIFT E INTO TUE
NIGHT BEFORE MORE QUICKLY MOVING SE ON WED. PWATS ON TUE WILL BE
BETWEEN 1.5 AND 1.7 INCHES /NORMAL IS AROUND AN INCH/...WHICH WHEN
COMBINED WITH THE FORCING FROM THE UPPER LOW/CYCLONIC FLOW AND
UPSLOPE FLOW OFF THE GREAT LAKES IN SPOTS /ESPECIALLY OVER WRN UPPER
MI/...WILL RESULT IN DECENT PRECIPITATION PRODUCTION. THINK THAT
SOME SPOTS COULD SEE EASILY OVER AN INCH OF PRECIP ON TUE/EARLY TUE
NIGHT...DEPENDING ON SMALLER SCALE FEATURES THAT ARE NOT ENTIRELY
CLEAR AT THIS POINT. WHILE IT IS HARD TO GET TOO SPECIFIC ON
HEAVIEST PRECIP PLACEMENT/TIMING...THINK THAT MOST OF THE CWA WILL
SEE PERIODS OF RAIN TUE INTO TUE NIGHT...SO WILL INCREASE POPS TO
LIKELY IN MOST PLACES. WILL LEAVE THUNDER CHANCES TO A MINIMUM...BUT
WILL HAVE A CHANCE OF THUNDER OVER SCENTRAL AND WRN UPPER MI WHERE
CAPES WILL BE A BIT HIGHER AT AROUND 200J/KG DURING THE DAY TUE.
WITH THICK CLOUD COVER...MAX TEMPS ON TUE WILL BE IN THE MID 60S TO
LOW 70S...OR 5 TO POSSIBLY 10 DEGREES BELOW NORMAL.
WED WILL SEE DECREASING PRECIP CHANCES AS THE SYSTEM MOVES SE...BUT
DO LINGER CHANCE POPS THROUGH THE MORNING. BEHIND THE SYSTEM...AN
UPPER RIDGE DEVELOPS OVER THE REGION...WHICH WILL KEEP THINGS A BIT
DRIER THAN EARLY IN THE WEEK. MODELS DO POINT TO PRECIPITATION
OCCURRING ALONG A WARM FRONT THAT MOVES THROUGH THU INTO THU
NIGHT...BUT IT IS UNCERTAIN HOW MUCH PRECIP WILL MAKE IT INTO THE
CWA AS THE FRONT MOVES UNDER THE UPPER RIDGE AND INTO THE DRIER AIR.
WILL HAVE CHANCE POPS THU INTO THU NIGHT...AND SOME LINGERING POPS
INTO FRI.
UNCERTAINTY IS GREATER GOING INTO THE WEEKEND AS MODELS SHOW QUITE A
BIT OF VARIABILITY /RUN TO RUN AND MODEL TO MODEL/ WITH THE
STRENGTH/TRACK/TIMING OF A LOW PRESSURE SYSTEM MOVING SOMEWHERE IN
OR NEAR THE REGION. WHILE MODELS DO APPEAR TO AGREE WITH QPF ON
SAT/SAT NIGHT...THEY DO NOT AGREE ON THE REASON FOR THAT QPF...SO
CONFIDENCE IS LOWER THAN IT WOULD SEEM BY JUST LOOKING AT QPF.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 126 AM EDT MON AUG 18 2014
CHALLENGING FCST SHAPING UP OVER THE NEXT 24HRS AS WEAK DISTURBANCES
MOVE INTO THE UPPER GREAT LAKES. WHILE VFR CONDITIONS SHOULD PREVAIL
OVERNIGHT AT KCMX/KSAW...LIGHT UPSLOPE FLOW AT BOTH TERMINALS MAY
LEAD TO LOW MVFR OR IFR CIGS AT TIMES. SCT SHRA SPREADING THRU NE
MN/NW WI SHOULD AFFECT KIWD OVERNIGHT AND KCMX TOWARD DAYBREAK...
BRINGING MVFR CONDITIONS WITH THE POTENTIAL FOR IFR. ALL TERMINALS
SHOULD GENERALLY BE MVFR FOR MUCH OF THE DAY WITH SHRA SCATTERED
AROUND THE AREA. INCREASINGLY MOIST LOW-LEVELS AND LIGHT UPSLOPE
FLOW SHOULD LEAD TO IFR CONDITIONS DEVELOPING THIS EVENING AT
KCMX/KSAW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 332 PM EDT SUN AUG 17 2014
EXCEPT FOR A BRIEF PERIOD OVER EASTERN LAKE SUPERIOR LATE MON NIGHT
INTO TUE WHEN WINDS MAY REACH 20-25 KTS UNDER A SHARPER PRES
GRADIENT BETWEEN HI PRES IN QUEBEC AND A LO TRACKING THRU THE UPPER
MIDWEST...EXPECT WINDS UNDER 20 KTS OVER THE NEXT WEEK AS A
RELATIVELY WEAK PRES GRADIENT DOMINATES THE UPPER GREAT LAKES ABOVE
THE CHILLY WATERS OF LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...ROLFSON
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
127 AM EDT MON AUG 18 2014
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 332 PM EDT SUN AUG 17 2014
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A NW FLOW ALF BTWN
A SLOWLY RETREATING...DEEP UPR TROF IN QUEBEC AND AN UPR RDG IN THE
PLAINS/UPR MS RIVER VALLEY. SFC HI PRES UNDER THIS RDG AXIS IS
LOCATED JUST NNW OF LK SUP. THE LLVL NE FLOW ON THE SRN FLANK OF
THIS HI IS FUNNELING SOME COOL...MOIST AIR INTO THE UPR LKS BLO
SHARP SUBSIDENCE INVRN ARND H85 AS SHOWN ON THE LOCAL 12Z RAOBS. THE
RESULT HAS BEEN A GOOD DEAL OF LO CLD COVER. THERE WAS EVEN SOME
DRIZZLE INTO THE EARLY AFTN OVER THE HIER TERRAIN OF THE NCENTRAL...
WHERE THE NE WIND PRESENTS A SHARPER UPSLOPE COMPONENT. BUT WITH
DAYTIME HEATING UNDER THE MID LVL DRY AIR AND SOME DRY H95-9
ADVECTION FM THE NE...THE LO CLDS ARE SHOWING SIGNS OF BREAKING
UP...ESPECIALLY IN AREAS THAT EXPERIENCE DOWNSLOPE FLOW. LOOKING TO
THE W...A VIGOROUS SHRTWV IN SRN SASKATCHEWAN IS MOVING EWD JUST N
OF THE CNDN BORDER AND TENDING TO SUPPRESS THE UPR RDG IN THE
PLAINS. THERE IS ANOTHER WEAKER SHRTWV AHEAD OF THIS FEATURE MOVING
THRU MN. CLDS ALONG WITH SHOWERS/A FEW TS ASSOCIATED WITH THIS
DISTURBANCE/OVERALL H85 THETA E ADVCTN IN THE LARGER SCALE SW FLOW
AHEAD OF THE STRONGER SASKATCHEWAN SHRTWV ARE APRCHG DULUTH EARLY
THIS AFTN.
MAIN FCST CONCERNS INTO THIS EVNG ARE FOCUSED ON LO CLD TRENDS.
TIMING/COVERAGE OF SHOWERS ASSOCIATED WITH PAIR OF UPSTREAM SHRTWVS
ARE THE CONCERNS FOR LATER TNGT AND MON.
LATE TODAY/TNGT...ALTHOUGH THE COMBINATION OF SOME LLVL DRY ADVCTN
AND DAYTIME HEATING MAY BREAK UP THE LO CLDS NOW IMPACTING THE CWA
THRU THIS AFTN...FAIRLY HI INVRN BASE OBSVD ON THE 12Z RAOBS WL
PROBABLY MAINTAIN BKN LO CLDS AT MANY LOCATIONS NOT IMPACTED BY
DOWNSLOPING FLOW AS THE SLOWLY RISING LCL WL REMAIN UNDER THE HIER
INVRN BASE. BUT THE LATEST TRENDS INDICATE THESE CLDS SHOULD BE
ALMOST COMPLETELY GONE BY 00Z. AFTER THIS EVNG...CLD COVER/SCT
SHOWERS NOW APRCHG DLH ARE LIKELY TO SPREAD INTO THE WRN CWA IN
ADVANCE OF LEAD SHRTWV AND WHERE STRONGER H85 THETA E ADVCTN WL
DVLP. EXPECT THE LOWEST MIN TEMPS OVER THE INTERIOR E WHERE THERE IS
LIKELY TO BE A LONGER PERIOD OF MOCLR SKIES/LGT WINDS CLOSER TO SFC
HI MOVING FM ERN LK SUP INTO ADJOINING ONTARIO. ADDED SOME PATCHY
FOG TO THE FCST IN THIS AREA WHERE TEMPS ARE EXPECTED TO FALL BLO
THE CROSS OVER DEWPTS OBSVD THIS AFTN.
MON...MAIN SHRTWV NOW MOVING THRU SRN SASKATCHEWAN IS FCST TO MOVE
INTO MN DURING THE AFTN. ALTHOUGH SOME SCT SHOWERS ASSOCIATED WITH
THE LEAD DISTURBANCE/AREA OF H85 THETA E ADVCTN MAY SPREAD INTO THE
CENTRAL AND ERN CWA...THESE ARE MORE LIKELY TO WEAKEN WITH TIME AS
THE CLUSTER MOVES TOWARD THE SHRTWV RDG AXIS/DRIER MID LVL AIR ON
THE WRN FLANK OF THE SLOW MOVING QUEBEC TROF. MORE NMRS SHOWERS ARE
LIKELY TO MOVE INTO THE W HALF OF THE CWA IN THE AFTN UPON THE
ARRIVAL OF DEEPER MSTR/MORE VIGOROUS DYANMIC SUPPORT ASSOCIATED WITH
THE MORE VIGOROUS TRAILING SHRTWV IN THE PRESENCE OF DAYTIME
HEATING. WITH FCST MUCAPES NO HIER THAN 100-200 J/KG ASSOCIATED WITH
A GOOD DEAL OF CLD COVER/EXPECTED DAYTIME HI TEMPS MAINLY IN THE
60S...WL LEAVE OUT A MENTION OF TS EXCEPT OVER THE FAR W...WHERE THE
MORE UNSTABLE GFS HINTS MUCAPES MAY REACH 500 J/KG CLOSER TO THE
INCOMING DISTURBANCE/COLDER AIR ALF.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 332 PM EDT SUN AUG 17 2014
AT 00Z TUESDAY THE NEXT 500MB WAVE WILL BE SET UP ACROSS MN THROUGH
W ONTARIO. MID/LONG TERM MODELS INDICATE THAT THIS FEATURE WILL
DEVELOP INTO A LOW 12-18Z TUESDAY OVER E MN AND THE W HALF OF THE
MQT CWA. AT THAT POINT...LITTLE MOVEMENT WILL BE EXPECTED AT 500MB
UNTIL AFTER DAYBREAK WEDNESDAY...AS THE 500MB SITS AND SPINS ACROSS
UPPER MI AND LAKE SUPERIOR. THE SFC LOW SHOULD TRACK FROM N AND
CENTRAL MN AT 00Z TUESDAY NEAR THE WI/UPPER MI BORDER ON
TUESDAY...BEFORE EXITING ACROSS LAKE MI TUESDAY NIGHT...AND LOWER MI
ON WEDNESDAY. WITH UPPER MI STAYING ON THE N SIDE OF THE SFC LOW
EXPECT A PERIOD OF CLOUDY CONDITIONS...WITH AFTERNOON TEMPS ON
TUESDAY AVERAGING AROUND 5F BELOW THE SEASONAL NORMAL VALUES. THE
BEST CHANCE FOR PRECIP IS DIFFICULT TO PIN DOWN AT THIS POINT...AS
FCST MODELS VARY SIGNIFICANTLY WITH THE SMALLER SCALE FEATURES WITH
THIS DEVELOPING SYSTEM. WILL CONTINUE TO GO RELATIVELY GENERAL WITH
THE POPS AT THIS POINT. WILL KEEP TS POTENTIAL TO A MINIMUM...GIVEN
THE TRACK OF THE SFC LOW MAINLY TO OUR S...AND MU CAPE VALUES OVER
THE FAR W AOB 100J/KG FAR W TUESDAY MORNING. TUESDAY DURING THE DAY
DOESN/T LOOK MUCH MORE IMPRESSIVE...TOPPING OUT ALONG THE WI BORDER
GENERALLY AROUND 200 J/KG OR LESS /RESTRICTED TS MENTION TO CENTRAL
U.P./.
THE 500MB RIDGE WILL BRIEFLY BUILD OVERHEAD LATER WEDNESDAY INTO
EARLY THURSDAY. OUT OF THE WORK WEEK FROM TUESDAY ON...THIS SHOULD
BE THE DRIEST PERIOD. WILL TRY TO SHOW A BIT MORE IN OUR
FCST...DESPITE THE PW VALUES REMAINING 80-140 PERCENT OF NORMAL
/LOWEST E/.
THE CHANCE OF SHOWERS RETURN LATE THURSDAY INTO FRIDAY AS A
SHORTWAVE/TROUGH GLANCES THE AREA. TS MAY RETURN ON FRIDAY. EXPECT
WAA FRIDAY TO PUSH 850MB TEMPS UP TO 15-19C. IF CLOUDS AND PRECIP
CAN STAY TO A MINIMUM...SFC SHOULD SHIFT TO ABOVE NORMAL READINGS.
AS FOR THE OPEN HOUSE AT THE MQT NWS ON SATURDAY 10AM-2PM
EDT...THERE IS ENOUGH DISCREPANCIES AT THIS POINT IN THE FCST MODEL
DATA TO KEEP A GENERAL BLEND OR CONSENSUS GOING. BOTH THE GFS AND
ECMWF SHOW A 500MB LOW TO THE W OF UPPER MI AT 12Z.
HOWEVER...LOCATIONS VARY FROM N MANITOBA TO THE DAKOTAS...WITH A SFC
LOW OR TROUGH EITHER JUST TO OUR W OR OVER W UPPER MI. IF THE 17/00Z
AND 06Z GFS RUNS ARE CORRECT...WINDS NEAR 20KTS WILL BE POSSIBLE.
THE 12Z RUN DID DIMINISH THESE STRONG WINDS...DOWN TO AROUND 10KTS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 126 AM EDT MON AUG 18 2014
CHALLENGING FCST SHAPING UP OVER THE NEXT 24HRS AS WEAK DISTURBANCES
MOVE INTO THE UPPER GREAT LAKES. WHILE VFR CONDITIONS SHOULD PREVAIL
OVERNIGHT AT KCMX/KSAW...LIGHT UPSLOPE FLOW AT BOTH TERMINALS MAY
LEAD TO LOW MVFR OR IFR CIGS AT TIMES. SCT SHRA SPREADING THRU NE
MN/NW WI SHOULD AFFECT KIWD OVERNIGHT AND KCMX TOWARD DAYBREAK...
BRINGING MVFR CONDITIONS WITH THE POTENTIAL FOR IFR. ALL TERMINALS
SHOULD GENERALLY BE MVFR FOR MUCH OF THE DAY WITH SHRA SCATTERED
AROUND THE AREA. INCREASINGLY MOIST LOW-LEVELS AND LIGHT UPSLOPE
FLOW SHOULD LEAD TO IFR CONDITIONS DEVELOPING THIS EVENING AT
KCMX/KSAW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 332 PM EDT SUN AUG 17 2014
EXCEPT FOR A BRIEF PERIOD OVER EASTERN LAKE SUPERIOR LATE MON NIGHT
INTO TUE WHEN WINDS MAY REACH 20-25 KTS UNDER A SHARPER PRES
GRADIENT BETWEEN HI PRES IN QUEBEC AND A LO TRACKING THRU THE UPPER
MIDWEST...EXPECT WINDS UNDER 20 KTS OVER THE NEXT WEEK AS A
RELATIVELY WEAK PRES GRADIENT DOMINATES THE UPPER GREAT LAKES ABOVE
THE CHILLY WATERS OF LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KF
AVIATION...ROLFSON
MARINE...KC
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
417 AM CDT MON AUG 18 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 415 AM CDT MON AUG 18 2014
TODAY AND TONIGHT...INTERESTING PATTERN OVER THE NEXT 24-30 HOURS
LOOKS MORE LIKE AN OCTOBER-NOVEMBER SCENE RATHER THAN MID-AUGUST. A
SHORTWAVE OPEN TROUGH WITHIN THE PREVAILING WNW-ESE FLOW WILL SLOWLY
TRAVERSE ACRS THE REGION THRU TNGT...DRAGGING A SFC LOW PRES CENTER
WITH IT. NO REAL BONA FIDE FRONTS ARE ASSOCIATED WITH THIS LOW...BUT
THERE ARE SEVERAL SFC TROUGH SPOKES EMANATING FROM THIS SFC LOW AND
IT IS THESE DISTURBANCES WITHIN A HIGHLY MOIST ENVIRONMENT THAT WILL
PRODUCE EFFICIENT RAIN-MAKING STORMS THRU THE NEXT DAY OR SO.
ALREADY SEEING SLOW-MOVING STORMS OVER WRN WI CONTINUE TO SHIFT
E...AND THESE STORMS ARE WITHIN A PWAT ENVIRONMENT OF OVER 1.6
INCHES. THERE IS ALSO ENOUGH MIDLVL INFLOW TO PRODUCE TRAINING OF
STORMS PLUS MUCAPES OF 1000-2000 J/KG. THIS IS COMBINING TO PRODUCE
POCKETS OF HEAVY RAIN OVER W-CENTRAL WI...AND THE THINKING IS THAT A
SIMILAR ENVIRONMENT FOR TDA INTO TNGT WILL ALLOW FOR SIMILAR-TYPE
STORMS TO FORM LATER TDA AND TNGT. TIMING WILL BE TRICKY...BUT HAVE
GONE THE ROUTE OF SHOWING A PERIOD OF DRYNESS THRU THIS MRNG THEN
GRADUALLY INCRG POPS THRU THE DAY TDA INTO TNGT...BEFORE ENDING POPS
FROM W TO E OVERNIGHT INTO TUE MRNG AS THE SEMI-STACKED LOW PRES
SYSTEM SHIFTS INTO THE GREAT LAKES. GIVEN THAT THE SFC LOW DOES
REMAIN TO THE E OF THE PARENT UPR OPEN WAVE...THERE MAY WELL BE
CONTINUED PRECIP GENERATION THRU TNGT SO HAVE KEPT LIKELY POPS GOING
FOR MUCH OF THE CWFA LATE THIS AFTN THRU TNGT...ESP IN ERN PORTIONS.
WITH THE HIGH PWATS...SLOW STORM MOTION AND/OR TRAINING OF STORMS
AND ADDED LIFT...THERE IS STILL THE POTENTIAL FOR HEAVY RAIN AND
FLOODING. THE OTHER CONCERN...AND THIS IS FOR THIS MORNING...IS
DENSE FOG...PARTICULARLY FOR W-CENTRAL MN. HAD ALREADY SEEN A NUMBER
OF W-CENTRAL MN SITES DROP TO 1/4SM AND 1/2SM VSBY WITHIN AN
ENVIRONMENT THAT HAS NEARLY CALM WINDS AND DEWPOINT DEPRESSIONS OF
TWO OR LESS. THOUGH THERE IS A WIND SHIFT COMING IN FROM THE DAKOTAS
WITH ONE OF THE SFC TROUGHS...AM NOT CONVINCED IT WILL ARRIVE IN
ENOUGH OF A FORM TO MITIGATE DENSE FOG DEVELOPMENT SO HAVE OPTED TO
HOIST A DENSE FOG ADVY THRU DAYBREAK. THE MPX ARE AND HOPWRF MODELS
HIGHLIGHT THE REDUCED VSBY NICELY BUT...SURPRISINGLY...THE SREF IS
NOWHERE NEAR AS BULLISH SO HAVE GONE WITH THE SHORT-TERM MODELS.
THERE IS SOME CHANCE THAT THE ADVY MAY NEED TO BE ADJUSTED GIVEN OB
TRENDS BUT WILL MONITOR AND ADJUST AS NEEDED.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 415 AM CDT MON AUG 18 2014
THE SIMPLE TRANSITION FROM NORTHWEST FLOW TO SOUTHWEST FLOW WILL
BRING REPEATED CHANCES FOR SHOWERS AND THUNDERSTORMS THIS WEEK WITH
RAINFALL POTENTIAL FOR 1-2 INCHES FOR MOST LOCATIONS...AND HIGHER
AMOUNTS UNDER THUNDERSTORMS.
AT THE START OF THE PERIOD ON TUESDAY THE UPPER LEVEL WAVE
RESPONSIBLE FOR MONDAYS PRECIP WILL BE DRIFTING EASTWARD ACROSS
WISCONSIN...BUT FORECAST MODELS AGREE ON AN EMBEDDED SHORTWAVE
ROTATING AROUND THE BACKS SIDE ACROSS THE MN/WI BORDER...TO
EXPANDED POPS WESTWARD TUESDAY AFTERNOON. HIGH PRESSURE WILL BUILD
IN TUESDAY NIGHT...BUT BOUNDARY LAYER DEWPOINTS DONT REALLY DRY
OUT. THIS COMBINED WITH LIGHT WINDS AND CLEARING SKIES WILL
SUPPORT FOG DEVELOPMENT BY EARLY WEDNESDAY MORNING...SO WILL
CONTINUE THIS FROM THE PREVIOUS FORECAST.
THE HIGH PRESSURE WILL BE SHORTLIVED AS AN UPPER LEVEL LOW CARVES
OUT A HIGH AMPLITUDE TROUGH ALONG THE WEST COAST. THIS WILL LEAD TO
SOUTHWEST FLOW ACROSS THE CENTRAL CONUS...WITH A SHORTWAVE COMING UP
ACROSS THE DAKOTAS BY WEDNESDAY. THIS WILL SUPPORT SOUTHERLY LOW
LEVEL FLOW...AND H925 MOISTURE TRANSPORT SHOWS A DIRECT CONNECTION
TO THE GULF MOISTURE WEDNESDAY NIGHT. A WARM FRONT IS FORECAST TO BE
DRAWN OUT EAST/WEST ACROSS THE CWA...SO EXPECT AN MCS TO MOVE ACROSS
THE REGION. SPLIT THE 12HR PRECIP GRID INTO TWO 6HR WINDOWS TO SHOW
THE EASTWARD PROGRESSION OF THE MCS WHICH SHOULD MIRROR THE VEERING
LOW LEVEL JET.
MODELS SHOW THIS WARM FRONT LIFTING NORTHWARD...BUT REPEATED ROUNDS
OF CONVECTION MAY KEEP THE BOUNDARY FARTHER SOUTH THAN CURRENTLY
FORECAST. THIS WOULD HAVE A SIGNIFICANT IMPACT ON TEMPERATURES. IF
THE FRONT IS FARTHER NORTH...WILL SEE LESS CLOUD COVER AND HIGHS
CLOSER TO THE 90S. FOR NOW DID NOT STRAY FROM GUIDANCE AND HAVE
HIGHS IN THE LOWER 80S...BUT THE POTENTIAL IS THERE. SEVERE WEATHER
APPEARS POSSIBLE WITH ADEQUATE DEEP LAYER SHEAR AND INSTABILITY
ALONG AND SOUTH OF THE FRONT. HEAVY RAIN IS ALSO A THREAT WITH
TRAINING THUNDERSTORMS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1118 PM CDT SUN AUG 17 2014
WIDELY SCATTERED SHOWERS LATE THIS EVENING WILL BE FOLLOWED BY A
MORE ORGANIZED AREA OF ACTIVITY OVERNIGHT. PREFER THE RAP 0.5KM
AGL CONDENSATIONAL PRESSURE DEFICITS AS A GUIDE FOR CIGS IN THE
NEAR-TERM. THINK IFR CIGS/VSBYS WILL PLAGUE SITES INTO MID MORNING
MONDAY. THEN OCCASIONAL SHOWERS/TS ARE EXPECTED AS THE TROUGH
PASSES ACROSS TOMORROW. EAST/SOUTHEAST WINDS AHEAD OF THE WARM
FRONT...THEN SHIFT TO WEST/SOUTHWEST FOR TOMORROW. SPEEDS AROUND
OR BELOW 10 KTS THROUGH THE PERIOD.
KMSP...
CIGS ARE EXPECTED TO DECREASE OVERNIGHT WITH BKN-OVC IFR LEVEL
CIGS PERSISTING INTO MONDAY MORNING. SCATTERED SHRA/TS ARE
EXPECTED ON MONDAY. WIND SPEEDS STAY AOB 10 KTS THROUGH THE
PERIOD BUT SHIFT FROM EAST/SOUTHEAST TO SOUTHWEST ON MONDAY
MORNING.
/OUTLOOK FOR KMSP/
TUE...VFR. CHC MVFR WITH AFTERNOON TSRA. WINDS NW 5-10 KTS.
WED...VFR. WIND VRB AT 5KTS.
THU...VFR. CHC MVFR WITH TSRA. WINDS SSE 5-10 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR MNZ041>043-
047>050-054>058-064-065-073.
WI...NONE.
&&
$$
SHORT TERM...JPC
LONG TERM...JRB
AVIATION...LS
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1117 PM CDT SUN AUG 17 2014
.UPDATE...FOR 06Z AVIATION DISCUSSION BELOW
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 142 PM CDT SUN AUG 17 2014
TWO ROUNDS OF THUNDERSTORMS EXPECTED OVER THE NEXT 24 HOURS. THE
FIRST IS THIS AFTERNOON AND THE SECOND IS EXPECTED TOMORROW
MORNING IN MN AND AFTERNOON IN WI.
A NEARLY STATIONARY BOUNDARY IS ROUGHLY BISECTING THE FORECAST
AREA THIS AFTERNOON WITH DEWPOINTS IN THE MID TO UPPER 50S IN THE
FAR NORTHERN FORECAST AREA /CENTRAL MN AND NORTHWEST WI/ AND
LOWER 70 DEWPOINTS ACROSS SOUTH. ALONG AND SOUTH OF THE FRONT
THERE IS A PRONOUNCED INSTABILITY GRADIENT WITH SBCAPE VALUES
RANGING FROM 0-3000J/KG OVER THE SPAN OF 40-60 MILES. THE
SIGNIFICANT INCREASE IN SBCAPE WAS AIDED BY A COUPLE HOURS OF
SUNSHINE THIS AFTERNOON AND MOISTURE POOLING NEAR THE FRONT. THE
SHOWERS THIS AFTERNOON ARE STARTING TO UTILIZE THE LARGE CAPE
VALUES AND ARE NOW PRODUCING A FEW LIGHTNING STRIKES. THE 1830Z
LAPS SOUNDING NOW HAS A FREEZING LEVEL OF 15KFT AND PWAT VALUES OF
1.75"...PROVIDING A GREAT ATMOSPHERE FOR WARM RAIN PROCESSES AND
HIGH RAIN RATES FOR RELATIVELY SMALL SHOWERS. WE EXPECT THESE
INTENSE-SMALL SHOWERS TO CONTINUE MOVING EAST ACROSS EASTERN
MN...WITH A SLOW DIMINISHING TREND NEAR SUNSET.
WE INCREASED POPS AND KEPT THE MENTION OF HEAVY RAIN IN THE
FORECAST TOMORROW FROM 09-21Z...WITH THE EXPECTATION OF ANOTHER
COMPLEX OF THUNDERSTORMS EXPECTED TO MOVE OUT OF SOUTH DAKOTA AND
INTO WESTERN MN BEFORE SUNRISE. WE USED A BLEND OF THE 17.12Z GEM-
REG AND NEW AND IMPROVED 17.12Z NAM...WHICH ARE IN VERY GOOD
AGREEMENT WITH ONE ANOTHER. EARLY LOOK AT SOME THE CAM GUIDANCE
FOR TOMORROW IS ALSO TRENDING THIS WAY. THE UPPER LOW WEST OF LAKE
WINNIPEG AND TRAILING TROUGH AND STRONG PV ADVECTION SHOULD BE THE
FOCUS FOR THIS COMPLEX LATE TONIGHT AND TOMORROW. HARD TO IMAGINE THIS
SECOND COMPLEX MISSING THE FORECAST TOMORROW GIVEN HOW CLOSE WE
ARE NOW.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 407 PM CDT SUN AUG 17 2014
THE BACK EDGE OF THE AFOREMENTIONED COMPLEX WILL BE HEADED EAST
ACROSS ERN MN AND WRN WI AT THE BEGINNING OF THE PERIOD...WITH THE
POSSIBILITY OF RESIDUAL SHOWERS CONTINUING THROUGH MUCH OF THE
NIGHT...ESPECIALLY OVER WI. KEPT POPS IN THE CATEGORICAL RANGE
DURING THE EVENING WITH A GRADUAL TAPERING OVERNIGHT AS THE BEST
CHANCES SHIFT EAST. THE TROUGH WILL BECOME MORE NEGATIVELY TILTED
TUESDAY OVER THE WESTERN GREAT LAKES. DIURNAL SHOWER DEVELOPMENT
APPEARS LIKELY WITHIN A SOMEWHAT MOIST CYCLONIC FLOW EXTENDING
WEST INTO MN AND NORTHEASTERN IA.
SKIES WILL CLEAR TUESDAY NIGHT WITH THE SURFACE RIDGE AXIS ALIGNED
OVER THE EASTERN CWA. EXPECTING AREAS OR WIDESPREAD FOG TO DEVELOP
FROM CENTRAL TO SERN MN EASTWARD INTO WI. THERE MAY BE ENOUGH
RETURN FLOW DEVELOPING LATE TO PRECLUDE FOG FROM BECOMING AS
WIDESPREAD ACROSS SRN AND WRN MN.
MID LEVEL RIDGING WILL BUILD NORTHEASTWARD INTO THE MID MISSOURI
VALLEY DURING THE MIDDLE OF THE WEEK. IT WON/T QUITE REACH THE
CWA...SO THIS REGION OF THE COUNTRY IS LIKELY TO REMAIN UNSETTLED
THROUGHOUT MUCH OF THIS WEEK. THE FIRST WAVE TO RIDE NORTH OF THE
RIDGE WILL ARRIVE LATE WEDNESDAY THRU THURSDAY MORNING. INTRODUCED
LIKELY POPS ACROSS SRN MN WEDNESDAY NIGHT WHERE THE BEST JUXTAPOSITION
OF FORCING AND INSTABILITY WILL RESIDE. THE RESULTANT MCS WILL
DEVELOP OVER SODAK WEDNESDAY AFTERNOON AND TRACK EASTWARD INTO WI
BY MIDDAY THURSDAY.
THE RIDGE WILL RETREAT SOME FRIDAY AS A TROUGH BEGIN TO EJECT
EASTWARD FROM THE PACIFIC NORTHWEST. THE SOUTHWEST FLOW WILL SEND
ANOTHER WAVE INTO THE REGION FRIDAY AND SATURDAY WHEN POPS RETURN
INTO THE HIGH CHC RANGE.
BEYOND SATURDAY...MODELS DIVERGE SIGNIFICANTLY FROM EACH OTHER
AND FROM RUN TO RUN. YESTERDAY THEY SHOWED A STOUT HEAT WAVE OVER
THE MID/UPPER MISSISSIPPI VALLEY AND TODAY THEY SHOW A TROUGH WITH
SUB 560DM HEIGHTS. IF THE REST OF THE SUMMER IS ANY GUIDE...I
WOULD FAVOR THE LATTER SOLUTION FOR NOW.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1118 PM CDT SUN AUG 17 2014
WIDELY SCATTERED SHOWERS LATE THIS EVENING WILL BE FOLLOWED BY A
MORE ORGANIZED AREA OF ACTIVITY OVERNIGHT. PREFER THE RAP 0.5KM
AGL CONDENSATIONAL PRESSURE DEFICITS AS A GUIDE FOR CIGS IN THE
NEAR-TERM. THINK IFR CIGS/VSBYS WILL PLAGUE SITES INTO MID MORNING
MONDAY. THEN OCCASIONAL SHOWERS/TS ARE EXPECTED AS THE TROUGH
PASSES ACROSS TOMORROW. EAST/SOUTHEAST WINDS AHEAD OF THE WARM
FRONT...THEN SHIFT TO WEST/SOUTHWEST FOR TOMORROW. SPEEDS AROUND
OR BELOW 10 KTS THROUGH THE PERIOD.
KMSP...
CIGS ARE EXPECTED TO DECREASE OVERNIGHT WITH BKN-OVC IFR LEVEL
CIGS PERSISTING INTO MONDAY MORNING. SCATTERED SHRA/TS ARE
EXPECTED ON MONDAY. WIND SPEEDS STAY AOB 10 KTS THROUGH THE
PERIOD BUT SHIFT FROM EAST/SOUTHEAST TO SOUTHWEST ON MONDAY
MORNING.
/OUTLOOK FOR KMSP/
TUE...VFR. CHC MVFR WITH AFTERNOON TSRA. WINDS NW 5-10 KTS.
WED...VFR. WIND VRB AT 5KTS.
THU...VFR. CHC MVFR WITH TSRA. WINDS SSE 5-10 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...CLF
LONG TERM...BORGHOFF
AVIATION...LS
AREA FORECAST DISCUSSION
NWS JACKSON MS
330 PM CDT MON AUG 18 2014
.DISCUSSION...FORECASTING CONVECTIVE SYSTEMS CAN BE A PAIN IN THE
SUMMER...AND SUCH HAS BEEN THE CASE THIS GO ROUND. RATHER LARGE AND
MATURE THUNDERSTORM COMPLEX KNOCKING ON THE DOOR OF THE ARKLAMISS
DELTA EARLY THIS MORNING DECIDED TO DIMINISH RAPIDLY IN MAGNITUDE
AND COVERAGE AFTER SUNRISE AS IT PROGRESSED INTO THE NORTHERN
PORTIONS OF THE FORECAST AREA. ATMOSPHERIC LIFTING INHERENT WITH THE
INCOMING MID-LEVEL CONVECTIVE VORT MAX DID MANAGE TO SPARK A GOOD
DEAL OF SHOWERS AND STORMS OVER CENTRAL AND EASTERN AREAS ALTHOUGH
MUCH OF THIS ACTIVITY IS ALREADY EXITING TO THE EAST. I CAN
UNDERSTAND THE FRUSTRATION OF THOSE ANTICIPATING RAIN TODAY BUT THAT
HAVE YET TO RECEIVE ANY...BUT THE DAY IS NOT OVER YET AND THERE IS
STILL A CHANCE! GENERAL SUBSIDENCE IN THE IMMEDIATE WAKE OF THE
DEPARTING CONVECTIVE VORT WILL BE TOUGH TO OVERCOME...BUT FAR
SOUTHERN ZONES SHOULD REMAIN CLEAR OF THAT INFLUENCE INTO THE EARLY
EVENING WITH THE ENVIRONMENT IN THE WESTERN HALF OF ZONES BECOMING
GRADUALLY MORE CONDUCIVE TO THUNDERSTORM DEVELOPMENT AN HOUR OR TWO
BEFORE SUNSET. LATEST HRRR REFLECTIVITY SIMULATION DEPICTS A LOOSE
CLUSTER OF SHOWERS AND STORMS ORGANIZING NEAR I-20 OVER NORTHERN LA
IN THE NEXT FEW HOURS...AND THEN PROGRESSING TOWARD CENTRAL MS
BEFORE DIMINISHING BY MID TO LATE EVENING. THIS SOLUTION HAS SOME
MERIT...BUT IT IS MORE IMPORTANT TO NOTE THE SLIGHTLY PERTURBED
NORTHWEST FLOW SCENARIO REMAINING IN PLACE UNTIL LATE TOMORROW IS
CONDUCIVE FOR LOOSELY ORGANIZED AND SOMETIMES RANDOM CONVECTION.
AS MENTIONED...SHOWERS AND THUNDERSTORMS WILL CONTINUE TO REMAIN AT
LEAST A SLIGHT POSSIBILITY OVERNIGHT AND UNTIL LATER TUESDAY. THE
HIGHEST CHANCES WILL GENERALLY BE IN THE NORTHEAST HALF OF
ZONES...BUT EVEN THERE POPS REALLY NOT GREATER THAN 30 PERCENT. WILL
HAVE TO WATCH OUT FOR PATCHY FOG AND LOW CLOUD DEVELOPMENT BY
DAYBREAK TUESDAY...ESPECIALLY IN AREAS THAT RECEIVED DOWNPOURS
TODAY...ALTHOUGH I AM NOT ANTICIPATING A DENSE FOG ADVISORY BEING
NEEDED ANYWHERE.
FOR TOMORROW THE MAIN STORY WILL LIKELY BE MOTHER NATURE STARTING TO
TURN UP THE THERMOSTAT. OF COURSE WE WILL ALSO HAVE TO WATCH FOR A
FEW THUNDERSTORMS THROUGHOUT THE DAY...BUT CONFIDENCE IS PRETTY HIGH
ANY STORMS BY LATER ON IN THE AFTERNOON SHOULD BE CONFINED TO
SOUTHEASTERN ZONES OF MS. MAV HIGHS MAINLY IN THE 93-96 RANGE LOOK
ON TRACK WITH PEAK HEAT INDEX VALUES PEAKING NEAR OR SLIGHTLY ABOVE
THE CENTURY MARK IN A GOOD DEAL OF SPOTS.
ON WEDNESDAY THE UPPER LEVEL RIDGE WILL BUILD RIGHT ATOP THE
REGION...INCREASING HEAT AND LIMITING ANY ISOLATED AFTERNOON
THUNDERSTORMS TO SOUTH OF INTERSTATE TWENTY. TEMPERATURES WILL PEAK
IN THE MID TO UPPER 90S WITH PEAK HEAT INDEX VALUES NEAR OR SLIGHTLY
ABOVE 105 DEGREES.
AT THIS POINT THURSDAY AND FRIDAY LOOKING QUITE SIMILAR TO WEDNESDAY
IN TERMS OF HEAT AND HUMIDITY...ALTHOUGH ANY RAIN CHANCES SHOULD BE
EVEN MORE REMOTE. CONSIDERING THIS WILL LIKELY BE THE HOTTEST
STRETCH OF THE SUMMER SO FAR WE HAVE GONE AHEAD AND STARTING
MENTIONING LIMITED RISK FOR DANGEROUS HEAT IN THE HWO FOR WEDNESDAY
THROUGH FRIDAY. MODELS SUGGEST THE COMING WEEKEND MIGHT HOLD A
LITTLE MORE POTENTIAL FOR ACTUALLY REACHING FULL HEAT ADVISORY
CRITERIA...BUT THIS POTENTIAL IS STILL NOT YET HIGH ENOUGH TO BEGIN
THAT OFFICIAL ADVERTISEMENT.
MODELS TODAY CONTINUED TO PAINT THE PICTURE OF THE DOGGED RIDGE
STARTING TO BREAK DOWN EARLY NEXT WEEK...EVENTUALLY LEADING TO GOOD
RAIN CHANCES AND COOLER TEMPS BY THE MIDDLE OF NEXT WEEK. BUT THE
MIDDLE OF NEXT WEEK IS A WAYS OFF AND WE MUST BRACE FOR THE HOT
STRETCH TO COME. /BB/
&&
.AVIATION...SCATTERED SHRA/TSRA ARE MOSTLY CONFINED TO EASTERN MS
THIS AFTERNOON INTO THE EARLY EVENING AND WILL BRING A CHANCE FOR
REDUCED CIGS/VSYBS...BUT VFR CONDITIONS ARE ANTICIPATED OTHERWISE.
LATE TONIGHT INTO EARLY TUESDAY MORNING...LOW STRATUS AND FOG WITH
IFR/LIFR RESTRICTIONS WILL BE POSSIBLE AT ALL SITES. /EC/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 72 94 73 96 / 25 21 5 10
MERIDIAN 71 94 71 97 / 29 23 5 7
VICKSBURG 71 94 72 96 / 20 16 5 11
HATTIESBURG 75 95 74 96 / 15 18 8 17
NATCHEZ 74 93 73 94 / 14 15 6 17
GREENVILLE 72 96 74 97 / 23 20 5 7
GREENWOOD 71 94 73 96 / 28 24 5 7
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
BB/EC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
341 PM CDT MON AUG 18 2014
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 341 PM CDT MON AUG 18 2014
THE MAIN FORECAST ISSUE WILL BE THE POSSIBILITY OF SOME
THUNDERSTORM ACTIVITY IN THE FAR SOUTHERN CWA OVERNIGHT.
WEST NORTHWEST FLOW ALOFT IS FAIRLY WEAK AND A NEARLY STALLED
BOUNDARY ACROSS THE CWA CONTINUES TO DRIFT SOUTH TODAY. LITTLE IF
ANY DEVELOPMENT SHOULD DEVELOP ALONG THIS BOUNDARY TODAY INTO THIS
EVENING AS A FAIRLY HEALTHY CAP KEEPS THINGS QUIET...DESPITE
MODERATE INSTABILITY IN THE 1500 TO 2000 J/KG RANGE FOR CONVECTIVE
AVAILABLE POTENTIAL ENERGY. SOME SMALL POP-UPS ARE SHOWING UP JUST
NORTH OF THE CWA...BUT THERE SHOULD BE ENOUGH OF A CAP TO TAMP
MUCH FURTHER DEVELOPMENT IN THE NORTH.
LATER ON TONIGHT...A HEALTHY 40 TO 45 KT JET WILL DEVELOP OVER
KANSAS AND WILL CURVE EAST...MOSTLY LIKELY OVER NORTH CENTRAL
KANSAS. THIS WILL SET THE STAGE FOR SOME POTENTIAL LOW-LEVEL
CONVERGENCE ACROSS OUR SOUTHERN CWA IN NORTH CENTRAL KANSAS AND
FAR SOUTHERN NEBRASKA NEAR THE AFOREMENTIONED SURFACE BOUNDARY.
THIS COULD BE JUST ENOUGH SUPPORT FOR SOME SMALL HAIL AND GUSTY
WIND IN OUR FAR SOUTH AS WELL. THE HRRR IS TRENDING STRONGER WITH
SOME DEVELOPMENT OVER THE HIGH PLAINS THIS AFTERNOON...SUPPORTED
BY ANOTHER LOW-AMPLITUDE SHORTWAVE TROUGH. THIS COULD BE ENHANCED
BY THE DEVELOPING LOW-LEVEL JET IN KANSAS AS THIS POTENTIAL
CONVECTION HEADS SOUTH. THE NAM HAS BEEN ADVERTISING SOME ACTIVITY
IN THIS VICINITY FOR THE PAST COUPLE OF DAYS. THE PRUDENT ACTION
WOULD BE TO PUT A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS BACK
INTO THE FORECAST IN OUR SOUTH. OUR CHANCES OF RAIN ARE LARGELY
DEPENDENT ON INITIAL CONVECTION IN THE HIGH PLAINS WITHIN THE
STRONGLY UNSTABLE...YET STILL CAPPED ENVIRONMENT TO THE WEST AS
THE AFOREMENTIONED TROUGH ENTERS THE CENTRAL PLAINS. THE SREF
SOLUTIONS ARE ALSO COMING IN WITH STRONGER SIGNALS TOWARD
CONVECTION IN OUR SOUTH AS WELL.
FOR TUESDAY...KEEPING IT QUIET WITH THE THINKING THAT THERE
SHOULD BE ENOUGH OF A CAP FROM PRECLUDING DEVELOPMENT UNTIL THE
EVENING HOURS. HIGH PLAINS CONVECTION COULD DEVELOP DURING THE
DAY...BUT SHOULD HOLD OFF MAKING IT HERE UNTIL EVENING...WHEN A
LOW-LEVEL JET AXIS DEVELOPS JUST TO THE WEST OF THE CWA.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 341 PM CDT MON AUG 18 2014
GUIDANCE SUGGESTS UPPER TROPOSPHERIC RIDGING WILL EXIST OVER THE
CENTRAL CONUS TO START THE LONG TERM FORECAST PERIOD. THE RIDGE
AXIS IS EXPECTED TO SHIFT EAST SOMEWHAT BY THURSDAY OR FRIDAY
HOWEVER...ALLOWING FOR MORE OF A SOUTHWESTERLY UPPER TROPOSPHERIC
FLOW OVER OUR AREA LATE THIS WEEK INTO EARLY NEXT WEEK.
THE AXIS OF A 35-40KT LOWER TROPOSPHERIC JET STREAK...JUST ABOVE
THE BOUNDARY LAYER...IS EXPECTED DEVELOP FROM WESTERN KANSAS INTO
SOUTH CENTRAL NEBRASKA TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING.
THERMAL ADVECTION ALONG THIS AXIS APPEARS AS THOUGH IT WILL BE
SUFFICIENT FOR PRECIPITATION PRODUCTION ACROSS NORTHEASTERN
PORTIONS OF OUR CWA...A SOLUTION SUPPORTED BY QPF FIELDS FROM THE
NAM...OPERATIONAL GFS AND EC. WENT AHEAD WITH 20-30% POPS ACROSS
OUR NORTHEAST TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING AS A
RESULT.
ON OVERALL LACK IN OMEGA SHOULD THEN PROVIDE DRY CONDITIONS TO
OUR AREA THROUGH MUCH OF THE DAY WEDNESDAY. BY LATE WEDNESDAY
AFTERNOON HOWEVER...THE NAM AND OPERATIONAL GFS BOTH SUGGEST
CONVECTION WILL INITIATE OVER THE CENTRAL HIGH PLAINS...AND THEN
MOVE EAST INTO OUR AREA WEDNESDAY EVENING AND OVERNIGHT. GIVEN
THIS...WENT AHEAD WITH 20-30% POPS ACROSS MUCH OF THE CWA
WEDNESDAY EVENING AND NIGHT.
ALTHOUGH OMEGA IS EXPECTED TO REMAIN WEAK THROUGH THE DAY
THURSDAY AS WELL...FORECAST PROXIMITY SOUNDINGS FROM ACROSS THE
CWA...PER THE NAM AND OPERATIONAL GFS...SUGGEST A NEARLY DRY
ADIABATIC TEMPERATURE PROFILE WILL BE REALIZED FROM THE SURFACE TO
JUST ABOVE 700MB ACROSS MUCH OF THE CWA...THUS ALLOWING CONVECTIVE
TEMPERATURE READINGS TO BE REACH AND PROVIDING FOR ISOLATED
THUNDERSTORM DEVELOPMENT. THIS IS A SOLUTION ALSO SUPPORTED BY QPF
FIELDS FROM THE NAM...OPERATIONAL GFS AND EC. GIVEN ALL
THIS...WENT AHEAD WITH ~20% POPS ACROSS MUCH OF THE CWA THURSDAY
AFTERNOON AND EVENING.
HEADING INTO THURSDAY NIGHT AND BEYOND...GUIDANCE SUGGESTS
MULTIPLE UPPER TROPOSPHERIC PERTURBATIONS COULD MOVE OVER THE
CENTRAL PLAINS AS THE SOUTHWESTERLY UPPER TROPOSPHERIC FLOW
INTENSIFIES. ALLBLEND RESPONDED BY PROVIDING 20-50% POPS TO MANY
AREAS ACROSS THE CWA THURSDAY NIGHT THROUGH MONDAY...AND THESE
POPS WERE LEFT UNCHANGED FOR THE MOST PART.
FORECAST PROXIMITY SOUNDINGS FROM THE NORTHEASTERN CWA...PER THE
NAM AND OPERATIONAL GFS...SUGGEST STORM-ACCESSIBLE POTENTIAL
ENERGY WILL NOT EXCEED 200-300J/KG TUESDAY NIGHT INTO EARLY
WEDNESDAY MORNING AND THUS...WILL HOLD OFF FROM ANY MENTION OF
SEVERE WEATHER TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING.
CONVECTION ALONG THE CENTRAL HIGH PLAINS WEDNESDAY AFTERNOON AND
EVENING WILL LIKELY HAVE THE CAPABILITY TO BE STRONG...BUT THERE
IS CONSIDERABLE UNCERTAINTY AS TO HOW LONG THIS CONVECTION WILL BE
ABLE TO MAINTAIN ITS INTENSITY AS IT MOVES EAST INTO OUR AREA.
GIVEN THIS UNCERTAINTY...WILL HOLD OFF FROM ANY MENTION OF SEVERE
WEATHER ACROSS OUR AREA WEDNESDAY EVENING AND LET FUTURE SHIFTS
REEVALUATE. BEYOND WEDNESDAY EVENING...AT THIS TIME THERE ARE NO
OVERWHELMING SIGNALS OF A SIGNIFICANT SEVERE WEATHER OUTBREAK.
ALTHOUGH A FEW HIT AND MISS STRONG TO SEVERE STORMS PROBABLY
CANNOT BE RULED OUT...DUE TO THE UNCERTAINTY WILL LEAVE OUT ANY
MENTION OF SEVERE WEATHER WEDNESDAY NIGHT AND BEYOND.
LITTLE CHANGE IN THE LOWER TROPOSPHERIC AIR MASS SHOULD PROMOTE
SIMILAR TEMPERATURE READINGS FROM DAY TO DAY WEDNESDAY THROUGH
SATURDAY...WITH AFTERNOON HIGHS IN THE UPPER 80S AND 90S AND
OVERNIGHT LOWS IN THE 60S AND LOWER 70S EXPECTED FOR THE MOST
PART. BEYOND SATURDAY...GUIDANCE DOES SUGGEST A LOWER TROPOSPHERIC
BAROCLINIC ZONE WILL MOVE ACROSS THE AREA...THUS ALLOWING A COOLER
LOWER TROPOSPHERIC AIR MASS INTO THE REGION. AFTERNOON HIGHS IN
THE UPPER 70S TO MID 80S AND LOWS GENERALLY IN THE 60S ARE
CURRENTLY EXPECTED TO FINISH THE LONG TERM FORECAST PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1243 PM CDT MON AUG 18 2014
WITH WEAK WEATHER FEATURES AT THE SURFACE AND LIGHT FLOW
ALOFT...WEATHER WILL BE RATHER BENIGN FOR THIS FORECAST.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...HEINLEIN
LONG TERM...BRYANT
AVIATION...HEINLEIN
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1242 AM CDT MON AUG 18 2014
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 258 PM CDT SUN AUG 17 2014
THE MAIN FOCUS OF THIS FORECAST IS CENTERED AROUND A LOW-AMPLITUDE
SHORTWAVE TROUGH MAKING ITS WAY INTO THE NORTHERN/CENTRAL PLAINS.
HIGH INSTABILITY HAS DEVELOPED OVER OUR AREA AHEAD OF THIS TROUGH
WITH 3-5 J/KG CAPE INDICATED. WITH ERODING CAP AND TRENDS SHOWING
STRONGER BULK SHEAR AT 0-6KM IN THE 30 TO 35 KT RANGE THIS
EVENING...WE ARE POISED FOR SOME SEVERE WEATHER DEVELOPMENT. AN AREA
OF THUNDERSTORMS OVER NORTH CENTRAL NEBRASKA HAS ALREADY BECOME
STRONG ENOUGH TO WARN ON...WITH A CU FIELD DEVELOPING SOUTH OF
THIS INITIAL DEVELOPMENT. I EXPECT A BLOSSOMING OF THUNDERSTORMS
ALONG THE APPROACHING TROUGH THIS EVENING AND INTO THE OVERNIGHT.
WITH DECREASING INSTABILITY PAST MID-EVENING...IT MAY BE MORE
DIFFICULT TO PRODUCE SEVERE WEATHER...BUT NOT OUT OF THE QUESTION.
MODEST LOW- LEVEL JET NEAR 25 KTS WILL DEVELOP THIS EVENING THAT
COULD HELP SUSTAIN THUNDERSTORM ACTIVITY. THERE IS SOME AGREEMENT
BETWEEN THE HRRR AND WRF SOLUTIONS OF A POTENTIAL MCS TO SWING
THROUGH ROUGHLY THE NORTHERN HALF OF THE CWA. WITH EXPECTED SEVERE
PARAMETERS...WE COULD BE FAIRLY BUSY...AT LEAST FOR THE EVENING.
MOST OF THE CONVECTION SHOULD CLEAR THE CWA DURING THE OVERNIGHT
AS THE TROUGH CONTINUES EAST.
MONDAY SHOULD BE MAINLY DRY...BUT THE NAM IS INDICATING ANOTHER
PERTURBATION THAT COULD AFFECT THE SOUTHERN CWA IN KANSAS.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 258 PM CDT SUN AUG 17 2014
THE LONG TERM BEGINS VERY SUMMER-LIKE AND ENDS WITH SOME POTENTIAL
FOR A MORE WIDESPREAD PRECIPITATION DEVELOPMENT BY NEXT WEEKEND.
HOWEVER...THE DETAILS ARE VERY SKETCHY BEYOND ABOUT WEDNESDAY
REGARDING TIMING/LOCATION OF PRECIPITATION TOWARD THE END OF THE
WEEK.
THE MOST INTERESTING PART OF THE UPPER LEVEL WEATHER PATTERN
WILL BE CHANGES COMING NEXT WEEKEND. MODEL GUIDANCE IN GENERAL
IS FAIRLY CONSISTENT THE CENTRAL PLAINS WILL SEE THE FLOW
TRANSITION TO AN UPPER TROUGH BY SOMETIME NEXT WEEKEND. THAT
HAS THE POTENTIAL TO BRING COOLER WEATHER AND A DECENT SHOT
FOR PRECIPITATION AT THAT TIME.
IN THE MEAN TIME...MUCH OF THE WEEK IS QUITE SUMMER-LIKE
IN TERMS OF TEMPERATURES. LOOK FOR TEMPERATURES TO BE
SLIGHTLY ABOVE NORMAL THROUGH PROBABLY THURSDAY...IF NOT
FRIDAY. NORTH CENTRAL KANSAS WILL SEE TEMPERATURES WELL
INTO THE 90S ALL WEEK. FORTUNATELY THERE WILL BE A SHORT BREAK
FROM HIGHER HUMIDITY LEVELS MONDAY NIGHT AND TUESDAY. MOISTURE
WILL START TO INCREASE AGAIN LATER IN THE WEEK AS THE UPPER
TROUGH APPROACHES AND SOUTHERLY WINDS INCREASE.
PRECIPITATION-WISE...MOST SOLD ON LATE TUESDAY NIGHT AND
EARLY WEDNESDAY WITH OVERNIGHT CONVECTION IN FACE OF STRONG
WARM ADVECTION AND 40KT LOW LEVEL JET. COVERAGE DEFINITELY
FAVORS NORTHERN AREAS...AND MAYBE EVEN NORTH OF OUR FORECAST
ALL TOGETHER. TIGHTENED UP THE PRECIPITATION CHANCES IN THE
AREA WITH THIS IN MIND. HOWEVER...AM NOT EXPECTING MORE
THAN A TENTH OR TWO OF RAIN AT MOST.
DID NOT STRAY AT ALL FROM DAYS 4-7 GUIDANCE GIVEN TO US IN THE
GRIDS...PRIMARILY BECAUSE CONFIDENCE IS NOT HIGH ENOUGH TO MAKE
SIGNIFICANT CHANGES. THE GENERAL TREND IS FOR INCREASING STORM
CHANCES BEGINNING THURSDAY NIGHT AND INTO THE WEEKEND. TEMPERATURES
COULD START TO DROP A BIT NEXT WEEKEND SHOULD PRECIPITATION
MATERIALIZE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1240 AM CDT MON AUG 18 2014
PLENTY OF MID AND HIGH LEVEL CLOUD COVER IS PERSISTING ACROSS THE
REGION EARLY THIS MORNING...AND AS SKIES CLEAR FROM WEST TO
EAST...COULD SEE SOME LIGHT BR FORM TO OUR WEST...POTENTIALLY
IMPACTING KEAR WITH SOME MVFR BR AROUND SUNRISE.
OTHERWISE...GENERALLY LIGHT SOUTHEASTERLY WINDS OVERNIGHT WILL
SHIFT AND BECOME NORTHERLY DURING THE DAY ON MONDAY...WITH VFR
CONDITIONS EXPECTED THROUGH THE PERIOD.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...HEINLEIN
LONG TERM...MORITZ
AVIATION...ROSSI
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1151 PM CDT SUN AUG 17 2014
.SHORT TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 305 PM CDT SUN AUG 17 2014
...OUR PATTERN REMAINS UNSETTLED...AND WARMER THIS WEEK...
FORECAST CHALLENGES FOR THE SHORT TERM WILL BE THUNDERSTORM
CHANCES AND SEVERE POTENTIAL TONIGHT THROUGH MONDAY EARLY
AFTERNOON.
IT LOOKED FAIRLY QUIET WEATHER TO BEGIN THIS EVENING...HOWEVER IT
SEEMS LIKE THE SHORT RANGE MODELS ARE A BIT UNDERDONE WITH THE
CONVECTION OVER CENTRAL SOUTH DAKOTA BASES ON THE LATEST RADAR.
THE HRRR HAS A SHORTWAVE AND CONVECTION THAT DROPS SOUTHEAST
ACROSS THE FORECAST AREA. THIS EVENING...WHILE THE OTHER MODELS
ARE SLOWER AND LESS AGGRESSIVE UNTIL LATER TONIGHT. EVEN THE 18Z
NAM IS STILL DRY THIS EVENING. NOT SURE HOW HIGH TO GO EARLY...BUT
WILL INCLUDE ISOLATED THUNDERSTORMS FOR PARTS OF NORTHEAST
NEBRASKA EARLY THIS EVENING. THE STORM PREDICTION CENTER DOES HAVE
A SEVERE THUNDERSTORM WATCH OUT FOR COUNTIES JUST TO THE WEST OF
OUR FORECAST AREA THIS EVENING AND THE SLIGHT RISK FOR SEVERE
WEATHER DOES CLIP OUR WESTERN FORECAST AREA COUNTIES.
THE 12Z UPPER AIR MAPS SHOWED A RIDGE OVER THE SOUTHWEST U.S. WITH A
CLOSED LOW OVER SASKATCHEWAN AND LEADING SHORTWAVE TROF ENERGY OVER
MINNESOTA. THE STRONGER HEIGHT FALLS AT H5 WERE NOTED OVER
CANADA...ASSOCIATED WITH THIS NORTHERN SYSTEM. THERE WERE RIBBONS
OF POOLED H7 MOISTURE OVER THE PLAINS WITH THE H7 THERMAL RIDGE OVER
WESTERN NEBRASKA AND COLORADO. SIMILAR PATTERNS WERE NOTED AT H85.
THE OAX SOUNDING HAD A PWAT OF 1.44 INCHES WHICH WAS 134% OF NORMAL.
A MAX OF 185% OF NORMAL WAS CENTERED OVER KMPX.
AS THE EVENING PROGRESSES...A LOW LEVEL JET INCREASES TO 35-40KTS
OVER CENTRAL NEBRASKA...MEANWHILE THE SHORTWAVE TROF ENERGY OVER
CANADA EXTENDS SOUTHWARD INTO THE PLAINS. UPPER LEVEL JET
SUPPORT...OMEGA... FRONTOGENESIS AND THETA-E ADVECTION ALL
INCREASE. AS A RESULT...THE DETERMINISTIC MODELS INCREASE
CONVECTION OVER THE DAKOTAS AND THIS CONVECTION EXTENDS SOUTHWARD
INTO EASTERN NEBRASKA AND IOWA TONIGHT AND MONDAY. THERE IS A
GOOD H7 WARM AIR ADVECTION SIGNAL AND GOOD 7-8 DEG C H7 DEWPOINTS.
EXPECTED TRENDS LATER TONIGHT ARE WELL HANDLED BY THE CURRENT
FORECAST WITH INCREASING POPS INTO THE LIKELY CATEGORY AND WILL
TREND FARTHER SOUTH TO COVER POTENTIAL FOR INCREASED CONVERGENCE
CLOSER TO THE SURFACE LOW.
DEEP LAYER SHEAR IS FROM 30- 40KTS TONIGHT...HOWEVER DROPS CLOSER
TO 30KTS MONDAY. THE SURFACE AND H85 FRONT ARE STILL IN EASTERN
NEBRASKA MONDAY MORNING...AND GRADUALLY PUSH OUT OF THE FORECAST
AREA BY 00Z MONDAY. INSTABILITY IS 500-2000J/KG TONIGHT...BUT
INCREASES TO 3000+ MONDAY. FORECAST SOUNDINGS LOOK TO FAVOR
ELEVATED STORMS TONIGHT...HOWEVER THEY ARE MORE SURFACE BASED FOR
MONDAY. ALTHOUGH FREEZING LEVELS ARE HIGHER AND INSTABILITY IS
O.K. STRONGER SHEAR...PLUME OF STEEPER LAPSE RATES AND BETTER LOW
AND MID LEVEL FORCING MAY SUPPORT SOME SEVERE STORMS. SEVERE
WEATHER CHANCES CONTINUE INTO MONDAY AS THUNDERSTORMS WILL BE
ONGOING WITH INCREASED INSTABILITY...ALTHOUGH FORCING AND SHEAR
APPEAR TO BE NOT AS HIGH. TREND WITH HIGHER POPS IN THE
AM...DECREASING FROM WEST TO EAST IN THE AFTERNOON. STORM MOTION
IS AROUND 20KTS...BUT WITH HIGH PWATS/H7 DEWPOINTS AND POTENTIAL
FOR STORMS MOVING OVER THE SAME AREA COULD PRODUCE HEAVY RAIN.
MAINLY DRY FOR MONDAY NIGHT INTO TUESDAY WITH A WARM FRONT
SITUATED OVER NORTHERN KANSAS. THERE IS LIFT OVER THE FRONT AND
THE FRONT LIFTS NORTH TUESDAY NIGHT AND WEDNESDAY...SO HAVE
SCATTERED THUNDERSTORMS MENTIONED. WARMER HIGHS IN THE 90S CAN BE
EXPECTED SOUTH OF THE FRONT.
.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 305 PM CDT SUN AUG 17 2014
STILL QUITE A FEW MODEL DIFFERENCES WEDNESDAY NIGHT THROUGH
SUNDAY. IT LOOKS LIKE A FRONT WILL BE IN THE AREA WEDNESDAY NIGHT
THROUGH FRIDAY...WITH A MID LEVEL RIDGE TO OUR SOUTH AND A
FLATTER...TROF INFLUENCE TO OUR NORTH. WARM H85 TEMPS FROM 20-24
DEG C PERSIST THROUGH FRIDAY NIGHT...HOWEVER THE EC BRINGS COOLER
WEATHER IN FOR SATURDAY...WHILE THE GFS HOLDS OFF UNTIL SUNDAY
NIGHT.
&&
.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1150 PM CDT SUN AUG 17 2014
SHOWERS AND THUNDERSTORMS WILL CONTINUE TO PUSH THROUGH LNK AND OMA
SITES EARLY IN THE PERIOD. BEHIND THE RAIN MVFR VSBYS WILL BE
POSSIBLE AT BOTH OFK AND OMA AS LIGHT WINDS AND AMPLE MOISTURE ALLOW
FOG TO FORM. A FRONTAL BOUNDARY WILL THEN MAKE ITS WAY THROUGH THE
REGION TOMORROW MORNING...BRINGING VFR CONDITIONS AND GRADUALLY
TURNING WINDS TO THE NORTH MONDAY AFTERNOON.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZAPOTOCNY
LONG TERM...ZAPOTOCNY
AVIATION...KG
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
550 PM PDT TUE AUG 19 2014
.SYNOPSIS...A LOW PRESSURE SYSTEM DROPPING DOWN THE WEST COAST WILL
ACT UPON MONSOON MOISTURE IN PLACE LEADING TO A CHANCE OF
THUNDERSTORMS OVER SOUTHEAST CALIFORNIA...SOUTHERN NEVADA AND
NORTHWEST ARIZONA AT LEAST THROUGH WEDNESDAY. TEMPERATURES WILL
REMAIN SEVERAL DEGREES BELOW NORMAL.
&&
.UPDATE...
DID A QUICK UPDATE TO EXTEND POPS WEST INTO EASTERN SAN BERNARDINO
AND SOUTHERN CLARK FOR A FEW MORE HOURS THAN PREVIOUSLY
FORECAST...WHERE CONVECTION IS ONGOING. ALSO UPDATED TO INCREASE
POPS FARTHER WEST IN LINCOLN COUNTY WHERE AN OUTFLOW BOUNDARY IS
PROPAGATING FROM THE NORTH TOWARD THAT AREA. NEW CONVECTION HAS
DEVELOPED ON THAT BOUNDARY AND...WITH DEWPOINTS STILL ELEVATED
ACROSS NORTHWEST LINCOLN COUNTY...EXPECT A FEW MORE THUNDERSTORMS TO
DEVELOP. THE LATEST HRRR /22Z RUN/ DOES INDICATE SOME CONVECTION
WILL DEVELOP ACROSS NORTHERN LINCOLN AND TRACK SOUTHEAST INTO UTAH.
WILL KEEP AN EYE ON THIS AREA AS WELL AS THE ONGOING CONVECTION FROM
NIPTON TO SEARCHLIGHT TO LAUGHLIN.
&&
.PREVIOUS DISCUSSION...
217 PM PDT TUE AUG 19 2014
.SHORT TERM...THROUGH WEDNESDAY NIGHT...BUSY AFTERNOON. EARLY
MORNING THUNDERSTORMS WORKED OVER LINCOLN AND EASTERN MOHAVE
COUNTIES...DRY AIR PUNCHING IN FROM THE WEST HAS CLEARED OUT MOST OF
SAN BERNARDINO COUNTY...AND THE NARROW WEDGE IN BETWEEN OVER FAR
EASTERN SAN BERNARDINO...SOUTHERN CLARK AND WESTERN MOHAVE HAS LIT
UP WITH BIG STORMS THIS AFTERNOON. AS THE MAIN LOW OVER THE WEST
COAST DIGS FARTHER SOUTH WEDNESDAY...SOUTHWEST FLOW OVER OUR AREA
WILL BACK AROUND TO THE SOUTH...ALLOWING THE MOISTURE TO SLOSH BACK
TO THE WEST AND BRING THUNDERSTORM CHANCES BACK TO AREAS SOUTHEAST
OF A LINE FROM BARSTOW TO HIKO. THE SIERRA NEVADA RANGE MAY ALSO SEE
A FEW STORMS THANKS TO THE INFLUENCE OF THE LOW. SOME STORMS ARE
LIKELY TO PERSIST THROUGH WEDNESDAY NIGHT OVER THE EASTERN CWA WITH
THE LOW NEARBY.
.LONG TERM...THURSDAY THROUGH TUESDAY...VERY LITTLE CHANGE TO THE
PREVIOUS THINKING. MODELS HAVE COME INTO SLIGHTLY BETTER AGREEMENT
BRINGING AN UPPER LEVEL LOW ACROSS THE AREA IN THE LATE WEDNESDAY
THROUGH THURSDAY TIMEFRAME. THURSDAY IS EXPECTED TO BE THE MOST
ACTIVE OF THE LONG TERM PERIOD WITH A GENERAL DRYING TREND
THEREAFTER. I DID EXPAND POPS A BIT FURTHER WEST ON THURSDAY TO
ACCOUNT FOR THE SLIGHTLY SLOW ECMWF AND NAM SOLUTIONS. BASICALLY
KEEPING POPS IN EAST OF A PIOCHE...MT. CHARLESTON...MORONGO VALLEY
LINE AND THE BEST CHANCES OVER MOHAVE COUNTY AND THE CLARK COUNTY
MOUNTAINS. KEPT IN A MENTION OF SHOWERS/THUNDERSTORMS OVER
SOUTHEASTERN MOHAVE COUNTY THURSDAY NIGHT AS ECMWF PUSHES THE LOW
OVER THE AREA.
FOR FRIDAY AND SATURDAY KEPT ONLY A SLIGHT CHANCE OF THUNDERSTORMS
MENTIONED OVER MOHAVE COUNTY TO ACCOUNT FOR ANY LINGERING MOISTURE.
OTHERWISE EXPECT DRIER CONDITIONS AND A WARMING TREND INTO EARLY
NEXT WEEK. THERE DOESN`T APPEAR TO BE A STRONG SIGNAL OF RETURNING
MOISTURE THROUGH THE BEGINNING OF NEXT WEEK.
&&
.AVIATION...FOR MCCARRAN...STRONG TO SEVERE THUNDERSTORMS WILL
AFFECT AREAS SOUTHEAST OF THE TERMINAL THIS EVENING AND
OVERNIGHT...WHICH COULD PRODUCE OUTFLOW WINDS AT THE TERMINAL AT
SOME POINT. THUNDERSTORM CHANCES WILL MOVE BACK INTO ALL APPROACH
CORRIDORS WEDNESDAY...WITH THE LOWEST CHANCE IN THE BEATTY CORRIDOR.
THERE WILL ALSO BE A SLIGHT CHANCE AT THE TERMINAL.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...STRONG TO SEVERE THUNDERSTORMS WILL AFFECT AREAS NEAR
AND EAST OF THE COLORADO RIVER THIS EVENING AND OVERNIGHT...WITH
EXTREMELY HEAVY RAINFALL AND HIGH WINDS THE MAIN THREATS.
THUNDERSTORM CHANCES WILL AFFECT AREAS ROUGHLY EAST OF A LINE FROM
BARSTOW TO HIKO ON WEDNESDAY.
&&
.SPOTTER INFORMATION STATEMENT...SPOTTERS SHOULD REPORT INSTANCES OF
FLASH FLOODING...STRONG GUSTY WINDS...HAIL...AND BLOWING DUST
THROUGH WEDNESDAY.
&&
$$
UPDATE...PADDOCK
SHORT TERM/AVIATION...MORGAN
LONG TERM...WOLCOTT
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1028 PM EDT TUE AUG 19 2014
.SYNOPSIS...
A SLOW MOVING AREA OF LOW PRESSURE WILL MOVE FROM THE CENTRAL GREAT
LAKES ON WEDNESDAY TO WESTERN LAKE ONTARIO BY THURSDAY. THIS WILL
PRODUCE AN UNSETTLED MIDWEEK PERIOD WITH OCCASIONAL SHOWERS AND
SCATTERED THUNDERSTORMS LATE TONIGHT THROUGH THURSDAY BEFORE THE LOW
WEAKENS BY FRIDAY. A FEW SHOWERS OR A THUNDERSTORM MAY BE LEFTOVER
FRIDAY AND SATURDAY...BUT MUCH OF THE TIME WILL BE RAIN FREE.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
REGIONAL RADAR IMAGERY LATE THIS EVENING CONTINUES TO SHOW A LINE OF
CONVECTION MAKING PROGRESS ACROSS LAKE ERIE TO NEAR LONG POINT AND
ERIE PA AT 0230Z. OBJECTIVE RUC ANALYSIS FROM THE SPC MESOANALYSIS
PAGE SHOWS VERY LIMITED INSTABILITY SUPPORTING THIS LINE...WITH
MUCAPE OF AROUND 500J/KG OVER CENTRAL LAKE ERIE. DESPITE THE
MARGINAL INSTABILITY...THE ESTABLISHED COLD POOL CONTINUES TO
SUPPORT CONVECTION ON THE LEADING EDGE OF OUTFLOW...ALTHOUGH
DIMINISHING LIGHTNING AND WARMING CLOUD TOPS CERTAINLY INDICATE THE
START OF A WEAKENING PHASE. RECENT RADAR TRENDS SUGGEST THE BAND OF
CONVECTION WILL SURVIVE THE TRIP DOWN LAKE ERIE AND ENTER CHAUTAUQUA
COUNTY FIRST AFTER 11PM...THEN REACH THE NIAGARA FRONTIER SHORTLY
AFTER MIDNIGHT. THE LEADING EDGE OF CONVECTION MAY CONTAIN GUSTY
WINDS AND ANY REMAINING STRONGER CONVECTIVE CORES MAY CONTAIN HEAVY
DOWNPOURS...BUT WINDS SHOULD NOT BE STRONG ENOUGH FOR ANY SEVERE
WEATHER. EXPECT AN ONGOING WEAKENING TREND...WITH THE CONVECTIVE
LINE FADING INTO SCATTERED SHOWERS AFTER ABOUT 2AM BY THE TIME IT
REACHES THE GENESEE VALLEY.
LATE TONIGHT THE MID LEVEL CLOSED LOW OVER THE UPPER MIDWEST WILL
MAKE EASTWARD PROGRESS INTO THE UPPER GREAT LAKES. A LEAD MID LEVEL
VORTICITY MAX AHEAD OF THE MAIN TROUGH WILL REACH WESTERN NY LATE
TONIGHT AND PROVIDE AN INCREASE IN LARGE SCALE ASCENT. AN
ILL-DEFINED WARM FRONT WILL ALSO MOVE INTO WESTERN NY LATE TONIGHT
WITH INCREASING WARM ADVECTION AND ISENTROPIC UPGLIDE IN THE
900-700MB LAYER. THIS WILL BRING THICKENING AND LOWERING CLOUDS
LATER TONIGHT WITH SHOWERS BECOMING LIKELY LATE ACROSS THE WESTERN
END OF THE STATE AGAIN TOWARDS DAYBREAK ON WEDNESDAY BEHIND THE
INITIAL LINE OF CONVECTION.
THE INCREASE IN CLOUD COVER...INCREASING SOUTHERLY
FLOW AND INCREASING DEWPOINTS WILL KEEP LOWS MILDER THAN RECENT
NIGHTS. EXPECT LOWS IN THE MID 60S ON THE LAKE PLAINS OF FAR WESTERN
NY...WITH LOWER 60S ELSEWHERE AND MID TO UPPER 50S ACROSS THE NORTH
COUNTRY.
ON WEDNESDAY THE MID LEVEL CLOSED LOW WILL PROGRESS TO LAKE HURON BY
LATE AFTERNOON. SEVERAL CONVECTIVELY AUGMENTED VORTICITY MAXIMA WILL
CROSS THE LOWER LAKES REGION DOWNSTREAM OF THE MAIN TROUGH DURING
WEDNESDAY...WITH EACH ONE PROVIDING A PERIOD OF ENHANCED LARGE SCALE
ASCENT. SUBTLE LOW LEVEL BOUNDARIES FROM OUTFLOW AND DIFFERENTIAL
HEATING WILL PROVIDE THE NECESSARY LOW LEVEL CONVERGENCE TO FOCUS
SHOWERS. THE TIMING AND PLACEMENT OF INDIVIDUAL BATCHES OF SHOWERS
WILL BE VERY DIFFICULT GIVEN THE WEAK AND STOCHASTIC NATURE OF THE
FINER SCALE FORCING MECHANISMS...BUT GIVEN THE PATTERN WILL CONTINUE
WITH CATEGORICAL POPS FOR THE DAY.
DESPITE CLOUD COVER...INCREASING BOUNDARY LAYER MOISTURE...MODEST
SURFACE HEATING...AND COOLING MID LEVELS WILL ALLOW FOR SUFFICIENT
INSTABILITY TO DEVELOP TO SUPPORT SCATTERED THUNDERSTORMS. PWAT
RISES TO AROUND 1.8 INCHES...AND LOW/MID LEVEL FLOW IS WEAK SO A FEW
STORMS MAY PRODUCE LOCALLY HEAVY RAINFALL. IF STORMS TRAIN LONG
ENOUGH OVER THE SAME AREA THIS COULD PRODUCE LOCALIZED FLOODING
ISSUES...BUT THE POTENTIAL APPEARS TOO LOW AND TOO ISOLATED TO
CONSIDER ANY TYPE OF FLOOD WATCH.
THERE SHOULD BE ENOUGH BREAKS IN THE RAIN ESPECIALLY ACROSS THE
EASTERN HALF OF THE AREA TO ALLOW THE LOWER ELEVATIONS TO REACH THE
LOWER 80S...WITH MID TO UPPER 70S ACROSS WESTERN NY AND THE HIGHER
TERRAIN WHERE CLOUD COVER WILL BE THICKER THROUGH THE ENTIRE DAY.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
WEDNESDAY`S RAINS WILL CONTINUE INTO THE OVERNIGHT HOURS AS THE
LOWER GREAT LAKES WILL REMAIN ENVELOPED IN A WARM AND MOIST AIRMASS
JUST AHEAD OF A BROAD VERTICALLY STACKED LOW CENTERED JUST TO OUR
NORTHWEST. SYNOPTIC-SCALE LIFT ASSOCIATED WITH THIS FEATURE SHOULD
BE ENOUGH TO SUSTAIN SHOWERS...AND POSSIBLY A FEW EMBEDDED
THUNDERSTORMS...FOR MUCH OF THE NIGHT EVEN WITH THE LOSS OF DIURNAL
INSTABILITY. AN AVERAGE OF ONE-QUARTER TO ONE-HALF INCH IS EXPECTED
ACROSS THE FORECAST AREA. HOWEVER GIVEN THAT PWATS WILL CONTINUE TO
RUN IN THE 1.6-2.0 INCH RANGE...LOCALLY HIGHER AMOUNTS IN EXCESS OF
AN INCH ARE LIKELY...PARTICULARLY FROM THE GENESEE VALLEY EAST WHERE
THE HIGHER PWATS WILL BE FOUND. THE WARM AND MOIST AIRMASS OVER THE
REGION WILL MAKE FOR A MUGGY NIGHT WITH LOWS RANGING FROM THE LOWER
60S ACROSS HIGHER TERRAIN TO THE UPPER 60S NEAR THE LAKES.
THE CENTER OF THE WEAKENING UPPER LOW WILL MOVE ACROSS THE FORECAST
AREA ON THURSDAY. THIS SHOULD RESULT IN ANOTHER ROUND OF SHOWERS AND
SCATTERED THUNDERSTORMS. WHILE THE DEEPEST MOISTURE WILL BE SHIFTING
TO THE HUDSON VALLEY BY THIS TIME...PWATS WILL STILL BE IN THE
NEIGHBORHOOD OF 1.5 INCHES AND THE VERY WEAK FLOW ALOFT COULD RESULT
IN LOCALLY HEAVY RAINS ONCE AGAIN...PARTICULARLY ACROSS EASTERN
PORTIONS OF THE FORECAST AREA. THE ABUNDANT CLOUD COVER SHOULD AID
IN KEEPING HIGHS IN THE MID 70S IN SPITE OF THE RELATIVELY WARM
AIRMASS OVERHEAD.
THE TROUGH WILL FINALLY MOVE AWAY TO THE EAST THURSDAY NIGHT...AND
SHOWERS SHOULD TAPER OFF FROM WEST TO EAST DURING THE EVENING HOURS
THOUGH GIVEN HOW SLOW THIS SYSTEM IS MOVING...CANNOT RULE OUT A FEW
SHOWERS HANGING AROUND THE EASTERN HALF OF THE AREA OVERNIGHT. IN
FACT THE CHANCE FOR SHOWERS WILL LINGER INTO FRIDAY NIGHT AS THE
REGION WILL REMAIN CAUGHT IN MOIST SOUTHEASTERLY LOW LEVEL FLOW
BETWEEN HIGH PRESSURE OVER ATLANTIC CANADA AND WEAK LOW PRESSURE
OVER THE WESTERN GREAT LAKES WHILE A STATIONARY FRONT WILL BE DRAPED
ACROSS THE GREAT LAKES...JUST TO OUR WEST. SHOULD THIS STATIONARY
FRONT END UP SLIGHTLY FARTHER WEST THAN CURRENTLY PROGGED...WESTERN
NEW YORK COULD END UP BEING MUCH WETTER THAN CURRENTLY
FORECAST...HOWEVER WILL STICK WITH LOWER CHANCE POPS FOR NOW PENDING
FURTHER GUIDANCE. TEMPERATURES WILL REMAIN SEASONABLE WITH HIGHS IN
THE MID TO UPPER 70S ON FRIDAY...THANKS MAINLY TO THE ADVECTION OF
SLIGHTLY COOLER AIR ALOFT IN THE WAKE OF THE UPPER LEVEL LOW.
NONETHELESS IT WILL CONTINUE TO FEEL QUITE STICKY WITH LOWS IN THE
LOW TO MID 60S FRIDAY NIGHT...THOUGH HIGHER ELEVATIONS MAY DIP INTO
THE UPPER 50S.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
THE POSITION OF THE AFOREMENTIONED STATIONARY FRONT WILL CONTINUE TO
BE THE BIG QUESTION MARK FOR THE COMING WEEKEND. THIS
FRONT...MARKING THE BOUNDARY BETWEEN A HOT CONTINENTAL AIRMASS OVER
THE CENTRAL U.S. AND RELATIVELY COOLER AND MOIST MARITIME AIR TO THE
EAST AND NORTH...WILL SERVE AS THE FOCAL POINT FOR SHOWERS AND
THUNDERSTORMS THROUGH MUCH OF THE WEEKEND. AT THIS POINT IT APPEARS
THAT THIS FRONT SHOULD LARGELY REMAIN JUST WEST OF OUR FORECAST
AREA...ACROSS OHIO AND THE CENTRAL GREAT LAKES...BUT WILL CARRY LOW
CHANCE POPS ACROSS WESTERN NEW YORK FOR THE TIME BEING GIVEN ITS
PROXIMITY TO OUR AREA.
THE UPPER LEVEL RIDGE WILL GRADUALLY SHIFT EAST THROUGH THE WEEKEND
AND INTO MONDAY...BRINGING WITH IT A WARMING AND DRYING TREND.
HOWEVER...IT CURRENTLY APPEARS THAT MORE UNSETTLED WEATHER WILL BE
ON THE WAY NEXT WEEK AS ANOTHER TRAIN OF SHORTWAVES MOVING ACROSS
THE NATION`S NORTHERN TIER WILL FLATTEN OUT THE RIDGE.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
A LINE OF CONVECTION OVER CENTRAL LAKE ERIE WILL REACH WESTERN NY
DURING THE 04Z-06Z TIME FRAME WITH A BRIEF PERIOD OF MVFR/IFR
RESTRICTIONS IN THE HEAVIER SHOWERS AND EMBEDDED THUNDERSTORMS. THE
LEADING EDGE OF CONVECTION MAY ALSO CONTAIN GUSTY WINDS. THIS LINE
OF CONVECTION SHOULD FADE AWAY INTO SCATTERED SHOWERS BY THE TIME IT
REACHES THE GENESEE VALLEY AROUND 06Z AS IT MOVES AWAY FROM STRONGER
INSTABILITY IN THE OHIO VALLEY.
BEHIND THE INITIAL LINE OF CONVECTION...EXPECT CIGS/VSBY TO BE
VFR...BUT MVFR WILL BECOME MORE LIKELY AGAIN IN THE HEAVIER SHOWERS
ON WEDNESDAY AS THE LOW LEVELS SATURATE AND SHOWER INTENSITY
INCREASES. A FEW OF THE HEAVIEST SHOWERS MAY PRODUCE BRIEF/LOCAL IFR
CONDITIONS...BUT TIMING AND PLACEMENT OF THESE LOWER CONDITIONS IS
VERY UNCERTAIN AT THIS TIME RANGE.
OUTLOOK...
WEDNESDAY NIGHT AND THURSDAY...OCCASIONAL SHOWERS AND THUNDERSTORMS
WITH ATTENDANT LOCALIZED REDUCTIONS TO IFR/MVFR.
FRIDAY AND SATURDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND
THUNDERSTORMS.
SUNDAY...MAINLY VFR.
&&
.MARINE...
WEAK LOW PRESSURE WILL MOVE FROM THE CENTRAL LAKES WEDNESDAY MORNING
TO NEAR THE WEST END OF LAKE ONTARIO BY THURSDAY MORNING WHERE IT
WILL DISSIPATE IN PLACE. THE PRESSURE GRADIENT WILL REMAIN WEAK
THROUGH THE END OF THE WEEK WITH RELATIVELY LIGHT WINDS AND FLAT
WAVE ACTION. A FEW THUNDERSTORMS ARE POSSIBLE TONIGHT THROUGH
THURSDAY WHICH MAY PRODUCE LOCALLY HIGHER WINDS AND WAVES.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...HITCHCOCK
NEAR TERM...HITCHCOCK
SHORT TERM...WOOD
LONG TERM...WOOD
AVIATION...HITCHCOCK
MARINE...HITCHCOCK
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
228 PM EDT MON AUG 18 2014
.SYNOPSIS...
HIGH PRESSURE WILL KEEP OUR WEATHER QUIET THROUGH EARLY TUESDAY.
AN INCREASING CHANCE OF SHOWERS AND THUNDERSTORMS CAN THEN BE
EXPECTED LATE TUESDAY INTO ESPECIALLY WEDNESDAY AND THURSDAY...AS
A LOW PRESSURE SYSTEM MOVES THROUGH THE GREAT LAKES REGION.
&&
.NEAR TERM /THROUGH TONIGHT/...
1045 AM UPDATE... BASED ON LATEST
VISIBLE SATELLITE LOOP SHOWING AN EXTENSIVE AREA OF STRATOCU
FORMING OVER A LARGE SECTION OF OUR AREA, I INCREASED SKY COVER
THROUGH 18Z. AFTER THAT TIME RUC SOUNDINGS SHOW RAPID INCREASING
AMOUNTS OF DRY AIR UNDERNEATH THE SUBSIDENCE INVERSION. WITH THAT
IN MIND WE SHOULD SEE A SUBSTANTIAL INCREASE IN SUNSHINE THIS
AFTERNOON, WITH A MOSTLY SUNNY SKY BY 21Z. WE CAN SEE THIS
HAPPENING ALREADY OVER NORTHERN NY. ASIDE FROM THE SKY CHANGE, OUR
TEMPS ARE ON TRACK.
645 AM UPDATE... BROAD SURFACE HIGH PRESSURE WILL SHIFT
FROM CENTRAL ONTARIO INTO WESTERN QUEBEC-NORTHERN NEW YORK TODAY
THROUGH TONIGHT. INTERESTINGLY ENOUGH...UNDER THE CENTER OF THE
HIGH...TIMMINS ONTARIO WAS DOWN TO 37 DEGREES AS OF 6 AM...AND
ROUYN-NORANDA IN EXTREME WESTERN QUEBEC WAS DOWN TO 34 DEGREES.
WHILE THE CENTER OF THE HIGH WILL PASS TO OUR NORTH...IT WILL
STILL DOMINATE THE WEATHER IN CENTRAL NEW YORK TO NORTHEAST
PENNSYLVANIA...KEEPING THINGS PRETTY QUIET IN THE NEAR TERM. AND
AS HINTED AT ABOVE...A CHILLY NIGHT TONIGHT ESPECIALLY MOHAWK
VALLEY-WESTERN CATSKILLS.
A VERY WEAK WAVE DROPPED THROUGH THE STILL BRISK NORTHWEST FLOW
ALOFT OVERNIGHT...ALLOWING SOME CLOUDS AND EVEN A COUPLE SPRINKLES
TO SETTLE ACROSS CENTRAL NEW YORK DURING THE PREDAWN HOURS.
HOWEVER...THE CLOUDS HAVE TENDED TO SCATTER OUT WHILE EDGING SOUTHWARD
ACROSS THE TWIN TIERS. THUS...PATCHY DENSE FOG AND/OR LOW STRATUS
HAS FORMED ESPECIALLY IN THE VALLEYS OF THE TWIN TIERS AS WELL AS
NORWICH AND SIDNEY. ALSO SOME LOW STRATUS HANGING OVER ITHACA. THOSE
CLOUDS FOR SOME AND VALLEY FOG FOR OTHERS WILL DISSIPATE THE NEXT
FEW HOURS...LEADING TO A MOSTLY SUNNY AND PLEASANT DAY WITH
TEMPERATURES A SHADE BELOW CLIMATOLOGICAL AVERAGES.
FOR TONIGHT...A WEAK SYSTEM BOUND FOR THE MIDATLANTIC COAST WILL
BE WELL SOUTH OF US...YET CLOSE ENOUGH FOR SOME INCREASE IN CLOUDS
TOWARDS DAWN FROM CENTRAL TWIN TIERS TO NEPA. HOWEVER...NY THRUWAY
CORRIDOR TO WESTERN CATSKILLS SHOULD REMAIN CLEAR ALL NIGHT. WHILE
NOT AS COLD AS THAT READING MENTIONED ABOVE IN EXTREME WESTERN
QUEBEC...STRONG RADIATIONAL COOLING WILL MANAGE TO SEND TEMPERATURES
INTO THE LOW TO MID 40S IN THE TYPICALLY COLDER SPOTS OF UPPER
SUSQUEHANNA-MOHAWK VALLEY-WESTERN CATSKILL VALLEYS FOR LOWS.
QUITE CHILLY FOR MID AUGUST. FARTHER SOUTH AND WEST...WHERE CLOUDS
WILL INCREASE LATE...LOWS WILL STILL BE ON THE COOL SIDE IN THE
UPPER 40S TO LOW 50S...EXCEPT FOR MID 50S TOWARDS WYOMING VALLEY
OF PA.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
345 AM UPDATE...
A TROUGH WILL DIG INTO THE UPPER MIDWEST AND CUT OFF AN UPPER LOW
ON TUESDAY...WITH A WEAK SURFACE LOW FORMING OVER EAST-CENTRAL
WISCONSIN AS A RESULT. WELL AHEAD OF THE LOW...WARM AIR ADVECTION
IN OUR REGION WILL ALLOW TEMPERATURES AND DEWPOINTS TO CREEP UP
ENOUGH FOR SOME MARGINAL INSTABILITY TUESDAY AFTERNOON...THOUGH
BETTER IN WESTERN PORTIONS OF NY-PA. I HAVE INCLUDED SLIGHT TO LOW
CHANCE OF SHOWERS AND THUNDERSTORMS /NOT STRONG/...FOCUSED MAINLY
WEST OF A TOWANDA-ITHACA-AUBURN LINE. MOST OF OUR AREA WILL BE DRY
TUESDAY...WITH NEAR NORMAL TEMPERATURES...AND EVEN A DECENT AMOUNT
OF SUNSHINE AT LEAST IN CENTRAL NY.
SOUTHWEST FLOW ALOFT TUESDAY NIGHT...AHEAD OF APPROACHING UPPER
LOW...WILL BRING MORE MOISTURE INTO THE COLUMN. EMBEDDED WEAK
WAVES WITHIN THE FLOW MAY REALIZE SOME SHOWERS...THOUGH WITH NO
DIURNAL HEATING...THEY SHOULD BE LIMITED IN COVERAGE. CLOUDS
THOUGH WILL DEFINITELY BE INCREASING.
WEDNESDAY-WEDNESDAY NIGHT...AREAWIDE CHANCES FOR SHOWERS WILL GO
UP MARKEDLY. BOTH UPPER LOW AND SURFACE LOW /AND ITS OCCLUDING
FRONT/ WILL ADVANCE ACROSS CENTRAL GREAT LAKES WEDNESDAY...THEN
ENTERING OUR REGION WEDNESDAY NIGHT. HOWEVER...SURFACE HIGH
PRESSURE RIDGE WILL BE HOLDING STRONG ACROSS NEW ENGLAND...AND
SOUTHEAST-TO-SOUTH LOW LEVEL FLOW FROM IT MAY HAVE STABILIZING
INFLUENCE ON AT LEAST OUR EASTERN ZONES. SO WHILE SHOWERS ARE A
GOOD BET...THUNDER CHANCES MAY BE A BIT MUTED EAST OF HIGHWAY 81.
FARTHER WEST...MARGINAL INSTABILITY WILL HAVE A LITTLE BETTER
CHANCE OF BEING REALIZED AS EMBEDDED THUNDER WITHIN THE SHOWERS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
230 PM UPDATE...
MEDIUM RANGE MODELS CONTINUE TO SUGGEST A RATHER BLOCKY PATTERN
ACROSS THE NORTHERN HEMISPHERE WHICH WILL MAKE THIS FORECAST NOT
THAT CLEAR CUT. THE INDIVIDUAL MODEL SOLUTIONS ARE NOT TOO FAR OFF
IN THE DETAILS...RIGHT NOW...BUT GIVEN THE NATURE OF ATMOSPHERIC
BLOCKS THEY COULD EASILY WAVER BACK AND FORTH DURING THE WEEK. AS
IT STANDS NOW...A CLOSED LOW OFF THE EASTERN SEABOARD WILL STILL
HAVE ENOUGH OF AN INFLUENCE TO KEEP A SOLID CHANCE FOR SHOWERS IN
THE REGION ON THURSDAY NIGHT. THEN...GFS AND ECMWF INDICATE
CNY/NEPA WILL COME UNDER THE INFLUENCE OF A COL AREA OF WEAK
RIDGING BETWEEN TWO CUTOFF LOWS WITH SFC HIGH PRESSURE NOSING
SOUTH FROM NEW ENGLAND. THIS WILL LIKELY LEAD TO A MAINLY DRY
FORECAST THROUGH THE WEEKEND...UNTIL A MORE PROGRESSIVE NORTHERN
STREAM TROF AND COLD FRONT APPROACHES FOR MONDAY. TEMPERATURES
THROUGH THE PERIOD LOOK TO BE NEAR NORMAL WITH HIGHS IN THE UPPER
70S AND LOWS IN THE UPPER 50S.
OVERALL CONFIDENCE IN THIS FORECAST IS LOW TO MEDIUM IN THIS PATTERN.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
1:45 PM UPDATE...
THE PRIMARY FOCUS IS THE FOG FORMATION IN ELM LATER TONIGHT INTO
THE EARLY MORNING. AS OVERNIGHT LOWS DROP BELOW THE AFTERNOON
CROSSOVER TEMP, IFR VSBYS MAY BE POSSIBLE BETWEEN 04Z AND 07Z. AS
FOG INCREASES ELM WILL PROGRESS INTO THE LIFR TERRITORY BY 08Z.
EXPECT LIFR CONDITIONS AT LEAST ON A TEMPO BASIS AT ELM THROUGH
ABOUT 0800-1200Z. BASED ON CLIMO WE SHOULD SEE A RETURN TO VFR
HERE BY 14Z.
ELSEWHERE VFR IS EXPECTED THROUGH THE END OF THE TAF PERIOD, WITH
A GRADUAL INCREASE IN MID CLOUDS AROUND 4KFT TOMORROW ESPECIALLY
SOUTHERN TERMINALS.
WINDS WILL BE LIGHT AND VARIABLE FOR ALL STATIONS IN THE REGION
THROUGH TOMORROW AFTERNOON.
OUTLOOK...
TUE-WED MORN...VFR.
WED AFTN-SAT...MVFR RESTRICTIONS POSSIBLE IN SHRA/TSRA.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MDP
NEAR TERM...HEDEN/MDP
SHORT TERM...MDP
LONG TERM...JAB
AVIATION...HEDEN
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
201 PM EDT MON AUG 18 2014
.SYNOPSIS...
HIGH PRESSURE WILL KEEP OUR WEATHER QUIET THROUGH EARLY TUESDAY.
AN INCREASING CHANCE OF SHOWERS AND THUNDERSTORMS CAN THEN BE
EXPECTED LATE TUESDAY INTO ESPECIALLY WEDNESDAY AND THURSDAY...AS
A LOW PRESSURE SYSTEM MOVES THROUGH THE GREAT LAKES REGION.
&&
.NEAR TERM /THROUGH TONIGHT/...
1045 AM UPDATE... BASED ON LATEST
VISIBLE SATELLITE LOOP SHOWING AN EXTENSIVE AREA OF STRATOCU
FORMING OVER A LARGE SECTION OF OUR AREA, I INCREASED SKY COVER
THROUGH 18Z. AFTER THAT TIME RUC SOUNDINGS SHOW RAPID INCREASING
AMOUNTS OF DRY AIR UNDERNEATH THE SUBSIDENCE INVERSION. WITH THAT
IN MIND WE SHOULD SEE A SUBSTANTIAL INCREASE IN SUNSHINE THIS
AFTERNOON, WITH A MOSTLY SUNNY SKY BY 21Z. WE CAN SEE THIS
HAPPENING ALREADY OVER NORTHERN NY. ASIDE FROM THE SKY CHANGE, OUR
TEMPS ARE ON TRACK.
645 AM UPDATE... BROAD SURFACE HIGH PRESSURE WILL SHIFT
FROM CENTRAL ONTARIO INTO WESTERN QUEBEC-NORTHERN NEW YORK TODAY
THROUGH TONIGHT. INTERESTINGLY ENOUGH...UNDER THE CENTER OF THE
HIGH...TIMMINS ONTARIO WAS DOWN TO 37 DEGREES AS OF 6 AM...AND
ROUYN-NORANDA IN EXTREME WESTERN QUEBEC WAS DOWN TO 34 DEGREES.
WHILE THE CENTER OF THE HIGH WILL PASS TO OUR NORTH...IT WILL
STILL DOMINATE THE WEATHER IN CENTRAL NEW YORK TO NORTHEAST
PENNSYLVANIA...KEEPING THINGS PRETTY QUIET IN THE NEAR TERM. AND
AS HINTED AT ABOVE...A CHILLY NIGHT TONIGHT ESPECIALLY MOHAWK
VALLEY-WESTERN CATSKILLS.
A VERY WEAK WAVE DROPPED THROUGH THE STILL BRISK NORTHWEST FLOW
ALOFT OVERNIGHT...ALLOWING SOME CLOUDS AND EVEN A COUPLE SPRINKLES
TO SETTLE ACROSS CENTRAL NEW YORK DURING THE PREDAWN HOURS.
HOWEVER...THE CLOUDS HAVE TENDED TO SCATTER OUT WHILE EDGING SOUTHWARD
ACROSS THE TWIN TIERS. THUS...PATCHY DENSE FOG AND/OR LOW STRATUS
HAS FORMED ESPECIALLY IN THE VALLEYS OF THE TWIN TIERS AS WELL AS
NORWICH AND SIDNEY. ALSO SOME LOW STRATUS HANGING OVER ITHACA. THOSE
CLOUDS FOR SOME AND VALLEY FOG FOR OTHERS WILL DISSIPATE THE NEXT
FEW HOURS...LEADING TO A MOSTLY SUNNY AND PLEASANT DAY WITH
TEMPERATURES A SHADE BELOW CLIMATOLOGICAL AVERAGES.
FOR TONIGHT...A WEAK SYSTEM BOUND FOR THE MIDATLANTIC COAST WILL
BE WELL SOUTH OF US...YET CLOSE ENOUGH FOR SOME INCREASE IN CLOUDS
TOWARDS DAWN FROM CENTRAL TWIN TIERS TO NEPA. HOWEVER...NY THRUWAY
CORRIDOR TO WESTERN CATSKILLS SHOULD REMAIN CLEAR ALL NIGHT. WHILE
NOT AS COLD AS THAT READING MENTIONED ABOVE IN EXTREME WESTERN
QUEBEC...STRONG RADIATIONAL COOLING WILL MANAGE TO SEND TEMPERATURES
INTO THE LOW TO MID 40S IN THE TYPICALLY COLDER SPOTS OF UPPER
SUSQUEHANNA-MOHAWK VALLEY-WESTERN CATSKILL VALLEYS FOR LOWS.
QUITE CHILLY FOR MID AUGUST. FARTHER SOUTH AND WEST...WHERE CLOUDS
WILL INCREASE LATE...LOWS WILL STILL BE ON THE COOL SIDE IN THE
UPPER 40S TO LOW 50S...EXCEPT FOR MID 50S TOWARDS WYOMING VALLEY
OF PA.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
345 AM UPDATE...
A TROUGH WILL DIG INTO THE UPPER MIDWEST AND CUT OFF AN UPPER LOW
ON TUESDAY...WITH A WEAK SURFACE LOW FORMING OVER EAST-CENTRAL
WISCONSIN AS A RESULT. WELL AHEAD OF THE LOW...WARM AIR ADVECTION
IN OUR REGION WILL ALLOW TEMPERATURES AND DEWPOINTS TO CREEP UP
ENOUGH FOR SOME MARGINAL INSTABILITY TUESDAY AFTERNOON...THOUGH
BETTER IN WESTERN PORTIONS OF NY-PA. I HAVE INCLUDED SLIGHT TO LOW
CHANCE OF SHOWERS AND THUNDERSTORMS /NOT STRONG/...FOCUSED MAINLY
WEST OF A TOWANDA-ITHACA-AUBURN LINE. MOST OF OUR AREA WILL BE DRY
TUESDAY...WITH NEAR NORMAL TEMPERATURES...AND EVEN A DECENT AMOUNT
OF SUNSHINE AT LEAST IN CENTRAL NY.
SOUTHWEST FLOW ALOFT TUESDAY NIGHT...AHEAD OF APPROACHING UPPER
LOW...WILL BRING MORE MOISTURE INTO THE COLUMN. EMBEDDED WEAK
WAVES WITHIN THE FLOW MAY REALIZE SOME SHOWERS...THOUGH WITH NO
DIURNAL HEATING...THEY SHOULD BE LIMITED IN COVERAGE. CLOUDS
THOUGH WILL DEFINITELY BE INCREASING.
WEDNESDAY-WEDNESDAY NIGHT...AREAWIDE CHANCES FOR SHOWERS WILL GO
UP MARKEDLY. BOTH UPPER LOW AND SURFACE LOW /AND ITS OCCLUDING
FRONT/ WILL ADVANCE ACROSS CENTRAL GREAT LAKES WEDNESDAY...THEN
ENTERING OUR REGION WEDNESDAY NIGHT. HOWEVER...SURFACE HIGH
PRESSURE RIDGE WILL BE HOLDING STRONG ACROSS NEW ENGLAND...AND
SOUTHEAST-TO-SOUTH LOW LEVEL FLOW FROM IT MAY HAVE STABILIZING
INFLUENCE ON AT LEAST OUR EASTERN ZONES. SO WHILE SHOWERS ARE A
GOOD BET...THUNDER CHANCES MAY BE A BIT MUTED EAST OF HIGHWAY 81.
FARTHER WEST...MARGINAL INSTABILITY WILL HAVE A LITTLE BETTER
CHANCE OF BEING REALIZED AS EMBEDDED THUNDER WITHIN THE SHOWERS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
305 AM UPDATE...
DIFFUSE LONG WAVE TROF WILL REMAIN FIXED OVER EASTERN CANADA THIS
PERIOD, EXTENDING SOUTHWESTWARD THROUGH NY AND PA. THIS WILL KEEP
OUR WEATHER UNSETTLED THROUGH THE WORK WEEK, WITH A CHANCE FOR A
SHOWER OR THUNDERSTORM EACH DAY.
THE HIGHEST POTENTIAL DAY FOR CONVECTION APPEARS TO BE THURSDAY,
WHEN A WEAK SURFACE WAVE RIDES OUT OF THE OHIO VALLEY. MID LEVEL
LAPSE RATES WILL INCREASE TO 6 TO 6.5 PER THE LATEST ECMWF
PROG...LOW END MARGINAL FOR DECENT CONVECTION BUT UNSTABLE ENOUGH
TO SUGGEST AN INCREASED THREAT FOR PRECIPITATION.
PREV DISCUSSION...
TROFFINESS CONTS AT THE BEGINNING OF THE LONG TERM. 12Z GFS IS
TRYING TO DVLP A REX BLOCK OVR THE NORTHEAST BY MID- WEEK. HV
UNDERCUT WPC GUIDANCE SLIGHTLY WITH HICHC POPS EXPECTED ON WED
NGT. PATTERN STILL LOOKS TO BE UP IN THE AIR AND NOT CONFIDENT
ENUF TO GO LKLY THIS FAR OUT.
CHC POPS CONTINUE EACH PD WITH UPR LOW SPINNING IN THE GULF OF MAINE
THRU THE END OF THE LONG TERM WITH 590 RIDGE BUILDING INTO THE
MIDWEST LVG CWA IN NW FLOW PATTERN. THIS PATTERN WL LKLY THROW
SUBTLE S/WVS AT RANDOM INTO THE NE U.S. IN CONTRAST, 12Z CMC KEEPS
AREA IN ZONAL FLOW DUE TO H5 RIDGE AXIS BEING SUPPRESSED DOWN ALONG
THE GULF COAST.
SFC HIPRES BUILDS IN FM CANADIAN MARITIMES AND SHUNTS CHC POPS TO
THE EAST BUT NOT COMPLETELY OUT OF THE AREA ON SATURDAY. SFC RIDGE
AXIS BUILDS EVEN FURTHER TO THE WEST SAT NGT ACCOMPANIED BY BUILDING
H5 RIDGE WHICH MAY LEAD TO A DRY PD DRG THE LATTER HALF OF THE
WEEKEND.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
1:45 PM UPDATE...
THE PRIMARY FOCUS IS THE FOG FORMATION IN ELM LATER TONIGHT INTO
THE EARLY MORNING. AS OVERNIGHT LOWS DROP BELOW THE AFTERNOON
CROSSOVER TEMP, IFR VSBYS MAY BE POSSIBLE BETWEEN 04Z AND 07Z. AS
FOG INCREASES ELM WILL PROGRESS INTO THE LIFR TERRITORY BY 08Z.
EXPECT LIFR CONDITIONS AT LEAST ON A TEMPO BASIS AT ELM THROUGH
ABOUT 0800-1200Z. BASED ON CLIMO WE SHOULD SEE A RETURN TO VFR
HERE BY 14Z.
ELSEWHERE VFR IS EXPECTED THROUGH THE END OF THE TAF PERIOD, WITH
A GRADUAL INCREASE IN MID CLOUDS AROUND 4KFT TOMORROW ESPECIALLY
SOUTHERN TERMINALS.
WINDS WILL BE LIGHT AND VARIABLE FOR ALL STATIONS IN THE REGION
THROUGH TOMORROW AFTERNOON.
OUTLOOK...
TUE-WED MORN...VFR.
WED AFTN-SAT...MVFR RESTRICTIONS POSSIBLE IN SHRA/TSRA.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MDP
NEAR TERM...HEDEN/MDP
SHORT TERM...MDP
LONG TERM...DJP/PVN
AVIATION...HEDEN/JSY
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1055 AM EDT MON AUG 18 2014
.SYNOPSIS...
HIGH PRESSURE WILL KEEP OUR WEATHER QUIET THROUGH EARLY TUESDAY.
AN INCREASING CHANCE OF SHOWERS AND THUNDERSTORMS CAN THEN BE
EXPECTED LATE TUESDAY INTO ESPECIALLY WEDNESDAY AND THURSDAY...AS
A LOW PRESSURE SYSTEM MOVES THROUGH THE GREAT LAKES REGION.
&&
.NEAR TERM /THROUGH TONIGHT/...
1045 AM UPDATE...
BASED ON LATEST VISIBLE SATELLITE LOOP SHOWING AN EXTENSIVE AREA
OF STRATOCU FORMING OVER A LARGE SECTION OF OUR AREA, I INCREASED
SKY COVER THROUGH 18Z. AFTER THAT TIME RUC SOUNDINGS SHOW RAPID
INCREASING AMOUNTS OF DRY AIR UNDERNEATH THE SUBSIDENCE
INVERSION. WITH THAT IN MIND WE SHOULD SEE A SUBSTANTIAL INCREASE
IN SUNSHINE THIS AFTERNOON, WITH A MOSTLY SUNNY SKY BY 21Z. WE CAN
SEE THIS HAPPENING ALREADY OVER NORTHERN NY. ASIDE FROM THE SKY
CHANGE, OUR TEMPS ARE ON TRACK.
645 AM UPDATE... BROAD SURFACE HIGH PRESSURE WILL SHIFT
FROM CENTRAL ONTARIO INTO WESTERN QUEBEC-NORTHERN NEW YORK TODAY
THROUGH TONIGHT. INTERESTINGLY ENOUGH...UNDER THE CENTER OF THE
HIGH...TIMMINS ONTARIO WAS DOWN TO 37 DEGREES AS OF 6 AM...AND
ROUYN-NORANDA IN EXTREME WESTERN QUEBEC WAS DOWN TO 34 DEGREES.
WHILE THE CENTER OF THE HIGH WILL PASS TO OUR NORTH...IT WILL
STILL DOMINATE THE WEATHER IN CENTRAL NEW YORK TO NORTHEAST
PENNSYLVANIA...KEEPING THINGS PRETTY QUIET IN THE NEAR TERM. AND
AS HINTED AT ABOVE...A CHILLY NIGHT TONIGHT ESPECIALLY MOHAWK
VALLEY-WESTERN CATSKILLS.
A VERY WEAK WAVE DROPPED THROUGH THE STILL BRISK NORTHWEST FLOW
ALOFT OVERNIGHT...ALLOWING SOME CLOUDS AND EVEN A COUPLE SPRINKLES
TO SETTLE ACROSS CENTRAL NEW YORK DURING THE PREDAWN HOURS.
HOWEVER...THE CLOUDS HAVE TENDED TO SCATTER OUT WHILE EDGING SOUTHWARD
ACROSS THE TWIN TIERS. THUS...PATCHY DENSE FOG AND/OR LOW STRATUS
HAS FORMED ESPECIALLY IN THE VALLEYS OF THE TWIN TIERS AS WELL AS
NORWICH AND SIDNEY. ALSO SOME LOW STRATUS HANGING OVER ITHACA. THOSE
CLOUDS FOR SOME AND VALLEY FOG FOR OTHERS WILL DISSIPATE THE NEXT
FEW HOURS...LEADING TO A MOSTLY SUNNY AND PLEASANT DAY WITH
TEMPERATURES A SHADE BELOW CLIMATOLOGICAL AVERAGES.
FOR TONIGHT...A WEAK SYSTEM BOUND FOR THE MIDATLANTIC COAST WILL
BE WELL SOUTH OF US...YET CLOSE ENOUGH FOR SOME INCREASE IN CLOUDS
TOWARDS DAWN FROM CENTRAL TWIN TIERS TO NEPA. HOWEVER...NY THRUWAY
CORRIDOR TO WESTERN CATSKILLS SHOULD REMAIN CLEAR ALL NIGHT. WHILE
NOT AS COLD AS THAT READING MENTIONED ABOVE IN EXTREME WESTERN
QUEBEC...STRONG RADIATIONAL COOLING WILL MANAGE TO SEND TEMPERATURES
INTO THE LOW TO MID 40S IN THE TYPICALLY COLDER SPOTS OF UPPER
SUSQUEHANNA-MOHAWK VALLEY-WESTERN CATSKILL VALLEYS FOR LOWS.
QUITE CHILLY FOR MID AUGUST. FARTHER SOUTH AND WEST...WHERE CLOUDS
WILL INCREASE LATE...LOWS WILL STILL BE ON THE COOL SIDE IN THE
UPPER 40S TO LOW 50S...EXCEPT FOR MID 50S TOWARDS WYOMING VALLEY
OF PA.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
345 AM UPDATE...
A TROUGH WILL DIG INTO THE UPPER MIDWEST AND CUT OFF AN UPPER LOW
ON TUESDAY...WITH A WEAK SURFACE LOW FORMING OVER EAST-CENTRAL
WISCONSIN AS A RESULT. WELL AHEAD OF THE LOW...WARM AIR ADVECTION
IN OUR REGION WILL ALLOW TEMPERATURES AND DEWPOINTS TO CREEP UP
ENOUGH FOR SOME MARGINAL INSTABILITY TUESDAY AFTERNOON...THOUGH
BETTER IN WESTERN PORTIONS OF NY-PA. I HAVE INCLUDED SLIGHT TO LOW
CHANCE OF SHOWERS AND THUNDERSTORMS /NOT STRONG/...FOCUSED MAINLY
WEST OF A TOWANDA-ITHACA-AUBURN LINE. MOST OF OUR AREA WILL BE DRY
TUESDAY...WITH NEAR NORMAL TEMPERATURES...AND EVEN A DECENT AMOUNT
OF SUNSHINE AT LEAST IN CENTRAL NY.
SOUTHWEST FLOW ALOFT TUESDAY NIGHT...AHEAD OF APPROACHING UPPER
LOW...WILL BRING MORE MOISTURE INTO THE COLUMN. EMBEDDED WEAK
WAVES WITHIN THE FLOW MAY REALIZE SOME SHOWERS...THOUGH WITH NO
DIURNAL HEATING...THEY SHOULD BE LIMITED IN COVERAGE. CLOUDS
THOUGH WILL DEFINITELY BE INCREASING.
WEDNESDAY-WEDNESDAY NIGHT...AREAWIDE CHANCES FOR SHOWERS WILL GO
UP MARKEDLY. BOTH UPPER LOW AND SURFACE LOW /AND ITS OCCLUDING
FRONT/ WILL ADVANCE ACROSS CENTRAL GREAT LAKES WEDNESDAY...THEN
ENTERING OUR REGION WEDNESDAY NIGHT. HOWEVER...SURFACE HIGH
PRESSURE RIDGE WILL BE HOLDING STRONG ACROSS NEW ENGLAND...AND
SOUTHEAST-TO-SOUTH LOW LEVEL FLOW FROM IT MAY HAVE STABILIZING
INFLUENCE ON AT LEAST OUR EASTERN ZONES. SO WHILE SHOWERS ARE A
GOOD BET...THUNDER CHANCES MAY BE A BIT MUTED EAST OF HIGHWAY 81.
FARTHER WEST...MARGINAL INSTABILITY WILL HAVE A LITTLE BETTER
CHANCE OF BEING REALIZED AS EMBEDDED THUNDER WITHIN THE SHOWERS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
305 AM UPDATE...
DIFFUSE LONG WAVE TROF WILL REMAIN FIXED OVER EASTERN CANADA THIS
PERIOD, EXTENDING SOUTHWESTWARD THROUGH NY AND PA. THIS WILL KEEP
OUR WEATHER UNSETTLED THROUGH THE WORK WEEK, WITH A CHANCE FOR A
SHOWER OR THUNDERSTORM EACH DAY.
THE HIGHEST POTENTIAL DAY FOR CONVECTION APPEARS TO BE THURSDAY,
WHEN A WEAK SURFACE WAVE RIDES OUT OF THE OHIO VALLEY. MID LEVEL
LAPSE RATES WILL INCREASE TO 6 TO 6.5 PER THE LATEST ECMWF
PROG...LOW END MARGINAL FOR DECENT CONVECTION BUT UNSTABLE ENOUGH
TO SUGGEST AN INCREASED THREAT FOR PRECIPITATION.
PREV DISCUSSION...
TROFFINESS CONTS AT THE BEGINNING OF THE LONG TERM. 12Z GFS IS
TRYING TO DVLP A REX BLOCK OVR THE NORTHEAST BY MID- WEEK. HV
UNDERCUT WPC GUIDANCE SLIGHTLY WITH HICHC POPS EXPECTED ON WED
NGT. PATTERN STILL LOOKS TO BE UP IN THE AIR AND NOT CONFIDENT
ENUF TO GO LKLY THIS FAR OUT.
CHC POPS CONTINUE EACH PD WITH UPR LOW SPINNING IN THE GULF OF MAINE
THRU THE END OF THE LONG TERM WITH 590 RIDGE BUILDING INTO THE
MIDWEST LVG CWA IN NW FLOW PATTERN. THIS PATTERN WL LKLY THROW
SUBTLE S/WVS AT RANDOM INTO THE NE U.S. IN CONTRAST, 12Z CMC KEEPS
AREA IN ZONAL FLOW DUE TO H5 RIDGE AXIS BEING SUPPRESSED DOWN ALONG
THE GULF COAST.
SFC HIPRES BUILDS IN FM CANADIAN MARITIMES AND SHUNTS CHC POPS TO
THE EAST BUT NOT COMPLETELY OUT OF THE AREA ON SATURDAY. SFC RIDGE
AXIS BUILDS EVEN FURTHER TO THE WEST SAT NGT ACCOMPANIED BY BUILDING
H5 RIDGE WHICH MAY LEAD TO A DRY PD DRG THE LATTER HALF OF THE
WEEKEND.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
635 AM UPDATE...
THE FOCUS CONTINUES TO BE ON DENSE FOG FORMATION OUTSIDE OF THE
LAKE STRATUS CLOUD COVER. ELM IS DEEP INTO IFR TERRITORY THIS
MORNING, WHILE BGM HAS BEEN FLIRTING WITH IFR VISIBILITY AS THE
MISTS ROLL UP THE HILLSIDE TOWARD THE TERMINAL.
EXPECT IFR CONDITIONS AT LEAST ON A TEMPO BASIS AT BGM AND ELM
THROUGH ABOUT 1330-1400Z.
ANOTHER ROUND OF DENSE FOG IS LIKELY TUESDAY MORNING. IFR
CONDITIONS ARE FORECAST AT ELM.
PREVIOUS DISCUSSION...
A COMPLICATED SCENARIO THIS MORNING. LAKE CLOUDS OFF ONTARIO WILL
PRODUCE AN OVERCAST STRATUS DECK. THIS DECK WILL GRADUALLY LOWER
INTO MVFR TERRITORY AS THE LOWER ATMOSPHERIC MOISTURE PROFILE THICKENS.
OUTSIDE OF THE LAKE CLOUDS, CLEARING SKIES WILL ALLOW TEMPERATURES
TO FALL WELL BELOW THE CROSSOVER TEMPS FROM THE PREVIOUS
AFTERNOON. WITH LIGHT WINDS IN PLACE, THIS APPEARS TO BE A GREAT
SCENARIO FOR DENSE FOG.
CURRENTLY ELM IS FORECAST TO DESCEND INTO IFR FOG BY AROUND 8Z.
THE PROBLEM IS THAT THE LAKE CLOUD STRATUS IS JUST NORTH OF ELM,
AND COULD COMPLETELY CHANGE THE SCENARIO TO MVFR IF THE WIND
SHIFTS THE CLOUDS BACK OVER THE TERMINAL.
CLOUDS SHOULD BURN OFF BY LATE MORNING. VFR CONDITIONS AND LIGHT
WINDS ARE FORECAST TODAY.
OUTLOOK...
MON NGT...EARLY MORNING RIVER VALLEY FOG AT ELM.
TUE-WED MORN...VFR.
WED AFTN-FRI...MVFR RESTRICTIONS POSSIBLE IN SHRA/TSRA DURING THE
AFTERNOON.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MDP
NEAR TERM...HEDEN/MDP
SHORT TERM...MDP
LONG TERM...DJP/PVN
AVIATION...DJP
AREA FORECAST DISCUSSION
NWS BISMARCK ND
318 PM CDT MON AUG 18 2014
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 318 PM CDT MON AUG 18 2014
DIURNAL CONVECTION THROUGH SUNSET THIS EVENING AND FOG TONIGHT
HIGHLIGHT THE SHORT TERM.
DIURNAL SCATTERED CONVECTION IS EXPECTED TO REMAIN FOCUSED ACROSS
THE SOUTH CENTRAL AND JAMES RIVER VALLEY GIVEN RADAR AND SATELLITE
TRENDS THROUGH 1930 UTC...AND THE 16-17 UTC HRRR ITERATIONS.
MODEST INSTABILITY AND WEAK SHEAR ARE EXPECTED TO KEEP STORMS
BELOW SEVERE LIMITS. HOWEVER...THE NON SUPERCELL TORNADO OR
LANDSPOUT PARAMETER HAS A LOCAL MAXIMA ACROSS THE JAMES RIVER
VALLEY INTO THE SOUTHERN RED RIVER VALLEY WITH STEEP LOW LEVEL
LAPSE RATES AND ENVIRONMENTAL VORTICITY. THUS...WOULD NOT BE
SURPRISED BY A FUNNEL CLOUD REPORT.
FOR TONIGHT...WITH WEAK SURFACE HIGH PRESSURE IN PLACE...CLEAR
SKIES...LIGHT WINDS AND PLENTIFUL MOISTURE FROM WEEKEND RAINS...AREAS
OF FOG ARE POSSIBLE ACROSS MUCH OF THE AREA TONIGHT.
TUESDAY WILL BE THE ONLY DRY DAY IN THE FORECAST UNDER SHORTWAVE
RIDGING BEFORE A RETURN TO AN ACTIVE WEATHER PATTERN THROUGH THE
EXTENDED.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 318 PM CDT MON AUG 18 2014
A SLOW MOVING TROUGH EXTENDING FROM THE NORTHWEST TERRITORIES WILL
PRODUCE CHANCES FOR WIDESPREAD SHOWERS/THUNDERSTORMS FROM WEDNESDAY
INTO THE WEEKEND. CHANCES FOR PRECIPITATION WILL CONTINUE THROUGH
THE EXTENDED...AS UNSETTLED SOUTHWESTERLY FLOW REMAINS OVER THE
AREA.
HEAVY RAINFALL IS EXPECTED OVER WESTERN AND CENTRAL PORTIONS OF THE
STATE WEDNESDAY INTO THURSDAY...WITH ADDITIONAL RAINFALL THROUGH THE
WEEKEND. WESTERN AND CENTRAL AREAS HAVE ALREADY BEEN SATURATED WITH
ABUNDANT RAINFALL...FLOODING ISSUES REMAIN A CONCERN.
TEMPERATURES WILL NEAR AVERAGE FOR WEDNESDAY AND THURSDAY. A
COOLER AIRMASS BEGINS MOVING INTO THE AREA BY FRIDAY MORNING...HIGHS
WILL RANGE BETWEEN 10 AND 15 DEGREES BELOW AVERAGE THROUGH THE REST
OF THE PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 318 PM CDT MON AUG 18 2014
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS MAY IMPACT KJMS
AND KBIS THROUGH SUNSET. THEREAFTER...AREAS OF FOG ARE POSSIBLE
TONIGHT WITH SURFACE HIGH PRESSURE IN PLACE. HOWEVER...IMPACTS TO
ANY ONE TERMINAL ARE UNCERTAIN.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...AYD
LONG TERM...AC
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1251 AM CDT MON AUG 18 2014
.UPDATE...
ISSUED AT 1240 AM CDT MON AUG 18 2014
HAVE DROPPED POPS ALL BUT THE FAR EAST FOR THE REST OF THE OVERNIGHT.
UPDATE ISSUED AT 1000 PM CDT SUN AUG 17 2014
WILL ALLOW SEVERE THUNDERSTORM WATCH 463 TO EXPIRE AT 10 PM.
DISORGANIZED CONVECTION CONTINUES ACROSS EASTERN PORTIONS OF
DICKEY AND LAMOURE COUNTIES...AND SHOULD BE MOVING OUT OF THE AREA
IN THE NEXT HOUR OR TWO. ISOLATED SHOWERS ARE DIMINISHING ACROSS
CENTRAL NORTH DAKOTA BUT WILL KEEP A SLIGHT CHANCE HERE THROUGH
MIDNIGHT. ANOTHER AREA OF CONVECTION WAS LOCATED OVER SOUTH
CENTRAL SASKATCHEWAN INTO FAR NORTHEAST MONTANA...POISED TO MOVE
INTO NORTHWEST NORTH DAKOTA. THIS AREA IS CLOSER TO THE UPPER LOW.
THE 00 UTC NAM...LATEST HRRR AND RAP INDICATE THIS WEAK CONVECTION
COULD HOLD TOGETHER PAST MIDNIGHT...THUS WILL KEEP A SLIGHT CHANCE
IN THE NORTHWEST PAST MIDNIGHT. WILL CONTINUE TO KEEP A CHANCE
THROUGH THE NIGHT OVER THE FAR SOUTHEAST CWA FOR NOW AS COLD FRONT
REMAINS BACK ACROSS CENTRAL NORTH DAKOTA. LATER SHIFTS MAY BE ABLE
TO CUT THIS BACK IF NO ADDITIONAL CONVECTION DEVELOPS.
UPDATE ISSUED AT 847 PM CDT SUN AUG 17 2014
REMOVED ANOTHER ROW OF COUNTIES FROM THE WESTERN PORTION OF THE
SEVERE THUNDERSTORM WATCH...PIERCE...SHERIDAN AND EMMONS. ALSO
TRIMMED BACK POPS A BIT OVER WESTERN NORTH DAKOTA. WILL TAKE A
CLOSER LOOK AT POPS WITH THE 10 PM UPDATE.
UPDATE ISSUED AT 643 PM CDT SUN AUG 17 2014
REMOVED HETTINGER...ADAMS...GRANT...MORTON...MERCER AND OLIVER
COUNTIES FROM SEVERE THUNDERSTORM WATCH 463. SEE THE RECENTLY
ISSUED SPC MESOSCALE DISCUSSION 1565 FOR DETAILS ON EXPECTED
TRENDS THROUGH 0045 UTC.
UPDATE ISSUED AT 401 PM CDT SUN AUG 17 2014
QUICK UPDATE TO ISSUE SEVERE THUNDERSTORM WATCH 463 VALID THROUGH
10 PM CDT.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 315 PM CDT SUN AUG 17 2014
SEVERE CONVECTION WILL HIGHLIGHT THE SHORT TERM FORECAST FOR THIS
AFTERNOON AND EVENING.
OVERALL...IN AGREEMENT WITH SPC THINKING FOR CONVECTIVE EVOLUTION
THE REMAINDER OF THIS AFTERNOON AND EVENING. SEE SPC MESOSCALE
DISCUSSION #1563 FOR DETAILS. IN GENERAL...SOME UNCERTAINTY EXISTS
ON HOW MUCH CONVECTION WILL FILL IN ALONG THE COLD FRONT CROSSING
US HIGHWAY 85 AS OF 20 UTC...AS THE 17 AND INCOMING 18 UTC HRRR
ITERATIONS SHOW LITTLE BETWEEN THE ONGOING STORMS ACROSS THE NORTH
CENTRAL AND SOUTHWEST. THIS IS IN OPPOSITION TO THE 12 UTC WRF-ARW
AND NMM AND GLOBAL GUIDANCE WHICH WOULD SUGGEST MORE WIDESPREAD
STORMS BY 21-00 UTC. LARGE HAIL AND DAMAGING WINDS ARE THE PRIMARY
THREATS. WHILE LOW LEVEL SHEAR IS WEAK...CANNOT RULE OUT AN
ISOLATED TORNADO GIVEN POTENTIAL DISCRETE SUPERCELL STRUCTURES.
STORMS SHOULD BE LARGELY INTO THE RED RIVER VALLEY BY 03 UTC. NON-
SEVERE SCATTERED THUNDERSTORMS WILL CONTINUE NORTHWEST THROUGH
SUNSET...IN ASSOCIATION WITH THE UPPER LOW ALOFT.
FOR MONDAY...ADDITIONAL ISOLATED TO SCATTERED STORMS...BEST
CHANCES EAST...WILL LINGER GIVEN COLD TEMPERATURES ALOFT WITH THE
UPPER LEVEL LOW DEPARTING INTO MINNESOTA.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 315 PM CDT SUN AUG 17 2014
AN ACTIVE WEATHER PATTERN WITH BELOW NORMAL TEMPERATURES WILL
HIGHLIGHT THE EXTENDED FORECAST.
AFTER A DRY TUESDAY...THE 12 UTC GUIDANCE SUITE IS IN AGREEMENT ON
A BROAD UPPER LEVEL TROUGH ESTABLISHING ITSELF ACROSS THE PACIFIC
NORTHWEST INTO THE NORTHERN PLAINS. THIS SUPPORTS A RATHER ACTIVE
WEATHER PERIOD WITH DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS
WEDNESDAY THROUGH THE WEEKEND. TEMPERATURES ARE ALSO EXPECTED TO
BE BELOW NORMAL AS A RESULT...POSSIBLY ONLY IN THE MID TO UPPER
60S FOR SOME LOCATIONS BY NEXT WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1240 AM CDT MON AUG 18 2014
AN UPPER LEVEL TROUGH WILL MOVE SOUTHEAST FROM ITS CURRENT LOCATION
OVER NORTH CENTRAL NORTH DAKOTA...INTO WESTERN WISCONSIN THROUGH THE
06 UTC TAF PERIOD. GREATEST THREAT FOR LATE MORNING AND AFTERNOON
THUNDER WILL BE AT KBIS AND KJMS...THUS THESE ARE THE ONLY TAFS WITH
A MENTION OF THUNDER AT THIS TIME. DID MENTION A VCSH AT KMOT AND
KDIK. MODELS ARE INDICATING SOME WRAP AROUND LOW LEVEL MOISTURE
DROPPING SOUTH INTO THE FORECAST AREA BEHIND THE UPPER LOW LATE
TONIGHT AND EARLY MONDAY MORNING. MENTIONED A SCATTERED MVFR CLOUD
LAYER MOST AREAS MONDAY MORNING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JPM
SHORT TERM...AYD
LONG TERM...AYD
AVIATION...TWH/JPM
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
737 PM EDT TUE AUG 19 2014
.SYNOPSIS...
A MASSIVE RIDGE WILL BUILD OVER EAST-CENTRAL CANADA FOR THE NEXT
WEEK. ANOTHER STRONG RIDGE WILL BUILD OVER THE SOUTHERN UNITED
STATES. SHORT-WAVES EMBEDDED IN THE WEAK FLOW MOVING UNDER THE
CANADIAN BLOCK WILL SLOW DOWN AND WEAKEN AS THEY MOVE THROUGH OUR
REGION. THIS WILL LEAD TO A POTENTIALLY PROLONGED PERIOD OF
UNSETTLED WEATHER. BUT IT SHOULD PROTECT US FROM THE LATE SEASON
HEAT BUILDING TO OUR SOUTH.
&&
.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
A PLEASANT EVENING IS IN STORE FOR MOST OF THE REGION AS A NEARLY
N/S RIBBON OF RELATIVELY LOWER PWAT AIR /AROUND 1.0/ SLIDES EAST.
CLOUDS...AND ISOLATED TO SCATTERED SHOWERS WILL AFFECT MAINLY THE
LOWER SUSQ VALLEY THROUGH ABOUT 01Z WED.
PRECIP CHCS WILL BE ESSENTIALLY ZERO ACROSS MUCH OF CENTRAL AND
WESTERN PORTIONS OF THE CWA THROUGH 04-06Z...BEFORE A SHIELD OF
ANVIL CIRRUS...THEN PRECIP ENTERS OUR NW ZONES IN ASSOCIATION
WITH AN AREA TSRA MOVING ACROSS EXTREME SE MICH ATTM.
TEMPS WILL SLOWLY COOL OFF FROM THE LOWER TO MID 70S THIS
EVENING...BUT WILL LINGER AROUND 80F ACROSS THE FAR SE ZONES
THROUGH 00Z.
&&
.SHORT TERM /MIDNIGHT THROUGH 6 PM WEDNESDAY/...
THE HIGH RES WRF ARW AND HRRR SHOWS CONVECTION MOVING ACROSS LAKE
ERIE THIS EVENING AND INTO OUR FAR NW ZONES TWD 06Z /THOUGH THE
HRRR HAS TRENDED TWD A FEW-SEVERAL HOUR LATER ONSET OF THE
CONVECTION/. THIS AREA OF SHRA/TSRA SHOULD STEADILY
WEAKEN/FRAGMENT AS IT ENCOUNTERS LOWER PWATS AND A COOLER/MORE
STABLE LLVL ENVIRONMENT RESIDING OVER CENTRAL PENN.
POPS AFTER 06Z WILL INCREASE GRADUALLY TO ABOUT 30-40 PERCENT
BY DAYBREAK ACROSS THE WESTERN HALF OF THE CWA...BUT WILL REMIAN
AOB 15 PERCENT FURTHER EAST ACROSS THE ENTIRE SUSQ VALLEY.
PERVIOUS DISC BELOW...
A SURGE OF CAPE AND PW INTO WESTERN PA IN THE SREF AND
NAM...SIMILAR TO OLDER GEFS/GFS IMPLY SOME MORE ORGANIZED RAIN
POSSIBLE ON WEDNESDAY. USED A BLEND TO GET THE POPS AND THE 12KM
NAM TO ADD SOME TEXTURE TO CONVECTION AND RAIN AREA THAT APPEARS
TO BE POISED TO MOVE WEST TO EAST ACROSS THE REGION WEDNESDAY.
THE SREF POPS/PDF IMPLIES SHOWERS COMING INTO WEST AROUND 1500 UTC
AND MOST OF CENTRAL TWO THIRDS OF REGION BY LATE EVENING. SREF IS
KIND OF OPTIMISTIC SOUTHEAST PA COULD HAVE YET ANOTHER MOSTLY
RAIN FREE DAY WEDNESDAY.
THE KEY FEATURES ARE THE RETROGRADING RIDGE OVER EASTERN CANADA
WHICH IS TAKING THE UMPH OUT OF THE SYSTEMS CUTTING UNDER THIS
FEATURE. IN MOST MODELS THE NEAR 1SD ABOVE NORMAL PW SURGES WEAKEN
AS THE MOVE INTO PA. THUS MORE OPTIMISTIC...SREF-LIKE IN THE WEST
THAN THE EAST WITH RAINFALL AND NOT REALLY CONFIDENT GOING LIKELY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
THE WEAKENING RIDGE OVER EASTERN CANADA WILL ALLOW FOR DIVERGENT
FLOW AS THE UPPER LEVEL LOW SLOWLY MOVES EASTWARD. DAYTIME
HEATING...DECREASING PRESSURE...MOIST SOUTHEASTERLY SFC FLOW...AND
WEST TO NORTHWESTERLY FLOW ALOFT SHOULD ALLOW FOR ENOUGH
SHEAR...FOR CHANCE TO LIKELY POPS EARLY WEDNESDAY EVENING. CAPE
VALUES ARE LOW...WITH AN AVG OF 500-1K J/KG THROUGHOUT MOST OF
CENTRAL PA. SO SCATTERED SHOWERS AND THUNDERSTORMS REMAIN POSSIBLE
EARLY WEDNESDAY EVENING. THESE WILL SLOWLY FADE AS THE EVENING
CONTINUES.
THURSDAY LOOKS LIKE ANOTHER UNSETTLED DAY...AS UPPER LOW MAKES
IT/S CLOSEST PASS TO PA...TRACKING ACROSS UPSTATE NY...WITH THE
850MB LOW MOVING THROUGH PA. COOL TEMPS ALOFT...COMBINED WITH
DIURNAL HEATING...SHOULD YIELD NUMEROUS SHRA AND TSRA BY THE
AFTERNOON. HAVE CONTINUED POPS IN THE LIKELY CATEGORY BASED ON 12Z
OPERATIONAL AND GEFS OUTPUT. DUE TO THE CHANGING POSITION AND
TIMING OF THE LOW...HAVE SLIGHTLY LOWERED POPS ALONG THE SOUTHERN
HALF OF THE CWA. THE SOUTHERLY LL JET AND PLUME OF HIGH PWATS WILL
HAVE PASSED NE OF THE AREA THURSDAY...LIMITING THE THREAT OF ANY
HVY RAINFALL. MODEL BLENDED QPF IS IN THE QUARTER TO HALF INCH
RANGE THURSDAY. BEFORE THE LOW PASSES...TEMPS COULD REACH UP TO
THE LOW 80S. AFTER THURSDAY/S NUMEROUS SHOWERS AND THE ADVECTION
OF COOLER TEMPS ALOFT...HIGH TEMPS SHOULD DROP BELOW NORMAL FOR
AUGUST...WITH MAXES MAINLY IN THE 70S THROUGH THE END OF THE WORK
WEEK INTO THE WEEKEND.
LATEST MED RANGE GUIDANCE POINTING TOWARD DRIER WX FRIDAY INTO
EARLY NEXT WEEK...AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD
THE REGION FROM THE MIDWEST. DAILY RING OF FIRE CONVECTION ON NE
PERIPHERY OF THIS RIDGE WILL THREATEN WESTERN PA DURING THE
FRI-SUN TIME FRAME...WHILE EASTERN PA IS LIKELY TO REMAIN DRY.
DESPITE APPROACH OF UPPER RIDGE...NO BIG WARM UP EXPECTED...AS
LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN
EASTERLY FLOW INTO CENTRAL PA. THERE MAY BE ISSUE WITH AM LOW
CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
AN ISOLATED SHOWER WILL BE POSSIBLE THIS EVENING ACROSS THE
SOUTH.
OTHERWISE THE MAIN CONCERN WILL BE MVFR AND IFR CONDITIONS
LATE...GIVEN LIGHT WINDS...MAINLY CLEAR SKIES...AND DEWPOINTS
HIGHER THAN WE HAVE SEEN THEM FOR MUCH OF THE SUMMER SEASON SO
FAR.
EXPECT THINGS TO IMPROVE WED MORNING...BUT THE REMAINS OF
CONVECTION TO THE WEST AND THE UPPER LVL TROUGH MOVING IN
WILL RESULT IN AT LEAST SOME SHOWERS. SOME THUNDERSTORMS
WITH HEAVY RAIN WILL BE POSSIBLE.
NOT A LOT OF CHANGE IN THE PATTERN BEFORE THE WEEKEND IF
THEN.
OUTLOOK...
THU-SAT...MORNING FOG CHANCES EACH DAY. OVERALL VFR...BUT CHC
OF MAINLY AFTERNOON SHRA/TSRA AND ASSOCIATED RESTRICTIONS.
SUN...MAINLY VFR. STILL CHANCE OF SHRA IN THE MORNING.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LAMBERT
NEAR TERM...GRUMM/LAMBERT
SHORT TERM...GRUMM/LAMBERT
LONG TERM...FITZGERALD/CERU
AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
116 AM EDT MON AUG 18 2014
.SYNOPSIS...
WEAK HIGH PRESSURE ATOP THE REGION THIS WEEKEND WILL GIVE WAY TO A
GRADUAL INFLUX OF MOISTURE ON MONDAY AND TUESDAY WITH IMPROVING
SOUTHWEST FLOW. A SERIES OF LOW PRESSURE SYSTEMS PASSING BY TO THE
NORTH WILL INCREASE THE CHANCES OF SHOWERS AND THUNDERSTORMS THROUGH
MIDWEEK...ESPECIALLY OVER THE MOUNTAINS.
&&
.NEAR TERM /THROUGH TODAY/...
0515 UTC UPDATE...WINDS WERE UPDATED WITH A BLEND OF THE NAM AND
ADJMAV...FAVORING THE FORMER BY TWO TO ONE TO ACCOUNT FOR GREATER
MOUNTAIN WINDS. POPS WERE ADJUSTED IN THE NC MOUNTAINS BASED ON
RADAR TRENDS TO THE WEST.
AS OF 930 PM...AS EXPECTED...PRECIP CONTINUES ITS WEAKENING
TREND...TO THE POINT WHERE ONLY A FEW PATCHES OF LIGHT RAIN AND
ISOLATED SHOWERS REMAINED ACROSS THE FCST AREA. WILL RETAIN A CHANCE
POP OVER THE NC MOUNTAINS...MAINLY S AND W OF I-40...TO ACCOUNT FOR
SHOWERS MOVING IN FROM SE TN. SOME MINOR ADJUSTMENTS WERE MADE TO
THE TEMP TREND BASED ON OBSERVATIONS.
REMAINDER OF PREVIOUS DISCUSSION...
MODELS SEEM TO DIFFER SOMEWHAT AT THIS POINT WITH THE 12Z HIRES WRF
PRODUCTS INDICATING A SECONDARY MCS DEVELOPING AND TRAILING THE
INITIAL LINE BY ABOUT 4-5 HOURS AND ENTERING THE MOUNTAIN ZONES JUST
AFTER MIDNIGHT. THAT SAID...THE HRRR AND LOWER RES 12Z NAM INDICATE
A LULL AS MENTIONED ABOVE WITH INITIAL MCS DECAY...WHICH WAS THE
PREFERRED SOLUTION IN THE FORECAST.
BY DAYBREAK EXPECTING COVERAGE OF SHOWERS AND PERHAPS A THUNDERSTORM
OR TWO TO BE INCREASING ACROSS MOST OF WESTERN NC...AND EVENTUALLY
SPREADING SOUTHEAST INTO THE NC/SC PIEDMONTS BY LATE MORNING INTO
EARLY AFTERNOON. PROFILES LOOK FAIRLY MOIST WHICH WILL INHIBIT
DIURNAL HEATING SOMEWHAT HOWEVER THERE WILL BE NEARLY 1000J/KG
SBCAPE PRESENT BY LATE MORNING. THUS CANNOT RULE OUT A STRONG TO
PERHAPS ISOLATED SEVERE THUNDERSTORM BEFORE THE PRIMARY UPPER
FORCING MECHANISM MOVES OUT LEAVING ONLY THERMODYNAMIC EFFECTS IN
PLAY. ONE ADDITIONAL NOTE...AS MENTIONED ABOVE PROFILES WILL BE
ABUNDANTLY MOIST THEREFORE ANY THUNDERSTORMS COULD PRODUCE
SUBSTANTIAL RAIN RATES LEADING TO MINOR FLASH FLOODING. FORTUNATELY
DUE TO 30-40KTS OF WESTERLY H5 FLOW AND CONTINUED SOUTHWESTERLY FLOW
BENEATH...IT DOES NOT LOOK AS IF ANY CELLS WILL ANCHOR. CONDITIONS
WILL SLOWLY IMPROVE TOWARDS THE LATE AFTERNOON ACROSS THE SOUTHWEST
WITH THE NORTHEASTERN ZONES TO FOLLOW AS THE WAVE DEPARTS. AS FOR
THE FORECAST...CHANCE POPS ARE FEATURED ACROSS THE MOUNTAINS WITH
ONLY SLIGHT CHANCE POPS ACROSS THE FOOTHILLS FOR THIS AFTERNOON AND
EVENING. POPS ON MONDAY WILL FEATURE LIKELY LEVELS ACROSS MUCH OF
WESTERN NC WITH SOLID CHANCE LEVEL POPS ELSEHWERE. TEMPERATURES WILL
BE COOLER ON MONDAY AS PARTLY/MOSTLY CLOUDY SKIES PREVAIL YIELDING
BELOW NORMAL TEMPERATURES.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
AS OF 255 PM SUNDAY...NEARLY ZONAL FLOW REMAINS ACROSS THE AREA THRU
THE PERIOD AS AN UPPER LOW MOVES TO THE GREAT LAKES AND A RIDGE
BUILDS OVER THE LOWER MS RIVER VALLEY AND GULF COAST. A SHORT WAVE
TO THE SOUTH MOVES INTO THE AREA TUE...ANOTHER SHORT WAVE MOVES
ACROSS THE NORTH TUE NITE WITH ANOTHER WEAK WAVE ACROSS THE AREA
WED. AT THE SFC...A QUASI STATIONARY FRONT REMAINS TO OUR NORTH WITH
A LEE TROF NEAR THE FALL LINE. THERE WILL BE WAVES OF MOISTURE
MOVING INTO THE AREA WITH THE WAVES...ALMOST MCS LIKE. HOWEVER...
THERE IS QUITE A BIT OF SPREAD IN THE GUIDANCE SOLUTIONS REGARDING
CONVECTIVE COVERAGE. IN ADDITION...THERE IS LITTLE IN THE WAY OF LOW
LEVEL SLY FLOW WITH LOW LEVEL RIDGING KEEPING THE WINDS MORE WLY.
ALSO...LFC LEVELS REMAIN HIGH ACROSS THE SOUTH...BUT DO LOWER ACROSS
THE MTNS AND NRN TIER WHERE LOW LEVEL MOISTURE INCREASES THE MOST.
THERE IS QUITE A BIT OF ELEVATED INSTABILITY HOWEVER...SO ANY
FORCING THAT CAN LIFT THE PARCELS TO THAT LEVEL WILL ALLOW CONVECTION
TO BE REALIZED. THEREFORE...HAVE CONTINUED THE PREV TREND OF HIGHEST
POP MTNS AND NRN TIER THRU THE PERIOD...WITH A DIURNAL TREND. THAT
SAID...KEEP POP ACROSS THE MTNS OVERNIGHT TO ACCOUNT FOR ANY MCS
ACTIVITY THAT DOES MAKE IT THIS FAR EAST. LOWS WILL REMAIN NEARLY
STEADY A LITTLE ABOVE NORMAL. HIGHS WILL BE NEAR TO SLIGHTLY ABOVE
NORMAL TUE...THEN WARM A COUPLE OF DEGREES WED.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 2 PM EDT SUNDAY...THE MEDIUM RANGE PICKS UP AT 00Z ON THURSDAY
WITH RELATIVELY FLAT UPPER RIDGING OVER THE SE CONUS AND A HEALTHY
LOOKING UPPER SHORTWAVE CROSSING THE SOUTHERN GREAT LAKES TO OUR
NORTH. OVER THE NEXT COUPLE OF DAYS...THE LONG RANGE MODELS HAVE THE
UPPER RIDGE RETROGRADING BACK TOWARDS THE WEST WHILE THE ABOVE
SHORTWAVE BECOME ABSORBED BACK INTO MEAN UPPER FLOW AND A BROADER
UPPER TROF DEVELOPS JUST OFF THE NEW ENGLAND COAST. FOR THE
REMAINDER OF THE PERIOD...THE RIDGE AXIS REMAINS IN PLACE TO OUR
WEST WHILE THE UPPER TROF BECOMES NEARLY STATIONARY AND MORPHS INTO
A CLOSED H5 LOW BY DAY 7.
AT THE SFC...OUR AREA IS EXPECTED TO REMAIN UNDER A WARM AND MOIST
AIR MASS THRU THE PERIOD WITH WEAK HIGH PRESSURE IN PLACE AND A
SERIES OF WEAK MESO LOWS THAT TRY TO SPIN UP TO OUR NORTH AND EAST.
AS WOULD BE EXPECTED...MODEL PLACEMENT AND TIMING OF THESE LOWS IS
SPORADIC BETWEEN RUNS WITH THE DEEPER LYR MOISTURE ASSOCIATED WITH
THE NEAR SFC FEATURES GENERALLY CONFINED TO OUR NORTH AND EAST. THE
DEEPER MOISTURE APPEARS TO SPREAD MORE TO THE WEST OVER THE WEEKEND
SO SAT AND SUN SHOULD BE OUR BEST SHOT AT WIDESPREAD DIURNAL
CONVECTION. OTHERWISE...POPS FOLLOW A TYPICAL LATE SUMMERTIME
DIURNAL SLIGHT CHANCE TO CHANCE. TEMPS WILL START OUT ABOUT A
CATEGORY ABOVE NORMAL ON THURS AND STEADILY COOL THRU DAY 7 WITH
VALUES ENDING RIGHT AROUND CLIMO.
&&
.AVIATION /05Z MONDAY THROUGH FRIDAY/...
AT KCLT...MODEL TIME HEIGHTS SHOW LOW VFR CLOUDS...WITH AN EVEN
LOWER LAYER AROUND DAYBREAK. WITH MODEL GUIDANCE DIFFERING ON JUST
HOW LOW DAYBREAK CIGS WILL BE...ONLY A VERY LOW VFR CIG WILL BE
CARRIED AT DAYBREAK. A GUIDANCE CONSENSUS ONLY LOWERS VSBY TO LOW
VFR BY DAYBREAK...BUT THE CONSENSUS DOES LOWER VSBY TO IFR TO THE
W...AND MVFR TO THE S AND N. CONVECTIVE CHANCES WILL WARRANT A
MENTION IN THE TAF ON TODAY...AS A MID LEVEL SYSTEM CROSSES THE
AREA. SW WINDS WILL PREVAIL...WITH SOME GUSTINESS DURING DAYLIGHT
HOURS.
ELSEWHERE...CONVECTION OVER E TN IS NOT EXPECTED TO SURVIVE THE LOSS
OF HEATING LONG ENOUGH TO REACH KAVL. MODEL TIME HEIGHTS ARE SHOWING
LOW CLOUDS...BUT NO FIRM CONSENSUS ON HOW LOW THEY WILL BE AT
DAYBREAK. FOR NOW A BLEND WILL BE USED...BRINGING CIGS TO LOW VFR BY
DAWN...EXCEPT MVFR AT KAVL. A BLEND OF GUIDANCE SUPPORTS MVFR VSBY
AT DAYBREAK. CONVECTIVE CHANCES WILL BE MUCH BETTER TODAY THAN
RECENTLY AS A MID LEVEL SYSTEM CROSSES THE AREA. SW WINDS WILL
PREVAIL...WITH GUSTINESS DURING DAYTIME HEATING...BUT WINDS SHOULD
CHANNEL UP VALLEY FORM THE NW AT KAVL.
OUTLOOK...UPPER LEVEL RIDGING WILL SET IN BY MIDWEEK WITH ENOUGH
MOISTURE IN THE PROFILE TO SUPPORT DIURNAL CONVECTION THROUGH WEEKS
END LEADING TO AFTERNOON TSRA RESTRICTIONS AND POSSIBLE EARLY
MORNING FOG.
CONFIDENCE TABLE...
05-11Z 11-17Z 17-23Z 23-05Z
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAVL HIGH 83% HIGH 86% HIGH 100% HIGH 100%
KHKY HIGH 98% HIGH 90% HIGH 100% HIGH 100%
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 95% HIGH 100% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...CDG/JAT/PM
SHORT TERM...RWH
LONG TERM...JPT
AVIATION...JAT
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
148 PM CDT MON AUG 18 2014
.UPDATE...
POOL OF DEEP MOISTURE/SHORTWAVE MOVING ACROSS WEAK LOW-LEVEL
BOUNDARY HELPING TO DEVELOP NUMEROUS SHWRS/STRMS ACROSS THE
SOUTH/SCATTERED NORTH. EXPECT THIS TREND TO CONTINUE INTO THE
EARLY EVE. WILL RAISE POPS SLIGHTLY FOR THE AFTERNOON EXCEPT
EXTREME NORTH. NO CHANGES OTHERWISE.
&&
AVIATION...18Z TAF DISCUSSION.
LOW-LEVEL MOISTURE WILL REMAIN HIGH INTO TUESDAY MORNING.
OUTSIDE OF DEVELOPING CONVECTION...EXPECT VFR CONDITIONS
INTO THE EVENING BUT MVFR/IFR LEVEL CIGS/VSBYS ARE AGAIN
EXPECTED TO DEVELOP OVERNIGHT...HANGING AROUND UNTIL 14-15Z
TUES. BNA/CSV MOST LIKELY TO SEE CONVECTION THRU 03Z TUES.
&&
.PREV DISCUSSION... /ISSUED 637 AM CDT MON AUG 18 2014/
UPDATE...
12Z TAF DISCUSSION.
AVIATION...
SCT -SHRA CONTINUE TO DEVELOP ACROSS THE MID STATE ALTHOUGH MAINLY
SOUTH OF AREA AIRPORTS...SO WILL MENTION VCSH AT BNA/CSV THROUGH
18Z IN LINE WITH LATEST HRRR MODEL. VFR CIGS EXPECTED AT BNA/CSV
TODAY...WHILE CURRENT IFR CIGS/VIS AT CKV WILL IMPROVE TO VFR BY
LATE MORNING. LIGHT SOUTHWEST TO WEST WINDS ARE ANTICIPATED
THROUGH THE TAF PERIOD.
SHAMBURGER
PREV DISCUSSION... /ISSUED 456 AM CDT MON AUG 18 2014/
DISCUSSION...
SHOWERS AND THUNDERSTORMS DEVELOPING OVER THE LAST COUPLE OF HOURS
SOUTH OF I-40. SOUTHERN MAURY AND MARSHALL COUNTIES APPEAR TO BE
EXPERIENCING THE HEAVIEST RAINFALL THIS MORNING...WITH RADAR
ESTIMATING AROUND 1 TO 2 INCHES AND MORE RAIN ON THE WAY. SHOWERS
APPEAR TO BE BACK BUILDING AND TRAINING OVER THE SAME
AREAS...FURTHER INCREASING THE THREAT FOR FLASH FLOODING FOR
SOUTHERN MIDDLE TENNESSEE. PWATS REMAIN AROUND 2 INCHES WITH
UNIDIRECTIONAL FLOW THROUGHOUT THE MORNING. THE BULK OF THIS
ACTIVITY WILL PUSH EAST THROUGHOUT THE MORNING...BUT MORE SHOWERS
WITH HEAVY DOWNPOURS WILL BE POSSIBLE THROUGHOUT THE DAY.
TUESDAY`S THUNDERSTORM ACTIVITY LOOKS TO BE MORE WIDELY
SCATTERED...WITH THE BEST CHANCE OVER THE CUMBERLAND PLATEAU
DURING THE EVENING HOURS. WEDNESDAY AND THURSDAY CONDITIONS BEGIN
TO DRY OUT AS HIGH PRESSURE BUILDS OVER THE LOWER MS VALLEY. WILL
STILL CARRY A SLIGHT CHANCE OF SHOWERS AND STORMS OVER THE PLATEAU
THROUGH THE END OF THE FORECAST PERIOD AS EAST TENNESSEE REMAINS
UNDER NORTHWEST FLOW AND IS INFLUENCED BY AN AREA OF LOW PRESSURE
MOVING ACROSS THE NORTHEAST U.S.
THE MAIN STORY AFTER TODAY WILL BE OUR WARMING TREND WITH THE HIGH
PRESSURE BUILDING JUST TO OUR SOUTHWEST...TEMPERATURES ARE
EXPECTED TO SOAR INTO THE MID TO UPPER 90S AFTER TUESDAY.
APPARENT TEMPS COULD BE AROUND 100 DEGREES FOR THE LATTER HALF OF
THE WORK WEEK. WARM TEMPS AND DRY WEATHER WILL CONTINUE INTO NEXT
WEEKEND.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
07
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
637 AM CDT MON AUG 18 2014
.UPDATE...
12Z TAF DISCUSSION.
&&
.AVIATION...
SCT -SHRA CONTINUE TO DEVELOP ACROSS THE MID STATE ALTHOUGH MAINLY
SOUTH OF AREA AIRPORTS...SO WILL MENTION VCSH AT BNA/CSV THROUGH
18Z IN LINE WITH LATEST HRRR MODEL. VFR CIGS EXPECTED AT BNA/CSV
TODAY...WHILE CURRENT IFR CIGS/VIS AT CKV WILL IMPROVE TO VFR BY
LATE MORNING. LIGHT SOUTHWEST TO WEST WINDS ARE ANTICIPATED
THROUGH THE TAF PERIOD.
SHAMBURGER
&&
.PREV DISCUSSION... /ISSUED 456 AM CDT MON AUG 18 2014/
DISCUSSION...
SHOWERS AND THUNDERSTORMS DEVELOPING OVER THE LAST COUPLE OF HOURS
SOUTH OF I-40. SOUTHERN MAURY AND MARSHALL COUNTIES APPEAR TO BE
EXPERIENCING THE HEAVIEST RAINFALL THIS MORNING...WITH RADAR
ESTIMATING AROUND 1 TO 2 INCHES AND MORE RAIN ON THE WAY. SHOWERS
APPEAR TO BE BACK BUILDING AND TRAINING OVER THE SAME
AREAS...FURTHER INCREASING THE THREAT FOR FLASH FLOODING FOR
SOUTHERN MIDDLE TENNESSEE. PWATS REMAIN AROUND 2 INCHES WITH
UNIDIRECTIONAL FLOW THROUGHOUT THE MORNING. THE BULK OF THIS
ACTIVITY WILL PUSH EAST THROUGHOUT THE MORNING...BUT MORE SHOWERS
WITH HEAVY DOWNPOURS WILL BE POSSIBLE THROUGHOUT THE DAY.
TUESDAY`S THUNDERSTORM ACTIVITY LOOKS TO BE MORE WIDELY
SCATTERED...WITH THE BEST CHANCE OVER THE CUMBERLAND PLATEAU
DURING THE EVENING HOURS. WEDNESDAY AND THURSDAY CONDITIONS BEGIN
TO DRY OUT AS HIGH PRESSURE BUILDS OVER THE LOWER MS VALLEY. WILL
STILL CARRY A SLIGHT CHANCE OF SHOWERS AND STORMS OVER THE PLATEAU
THROUGH THE END OF THE FORECAST PERIOD AS EAST TENNESSEE REMAINS
UNDER NORTHWEST FLOW AND IS INFLUENCED BY AN AREA OF LOW PRESSURE
MOVING ACROSS THE NORTHEAST U.S.
THE MAIN STORY AFTER TODAY WILL BE OUR WARMING TREND WITH THE HIGH
PRESSURE BUILDING JUST TO OUR SOUTHWEST...TEMPERATURES ARE
EXPECTED TO SOAR INTO THE MID TO UPPER 90S AFTER TUESDAY.
APPARENT TEMPS COULD BE AROUND 100 DEGREES FOR THE LATTER HALF OF
THE WORK WEEK. WARM TEMPS AND DRY WEATHER WILL CONTINUE INTO NEXT
WEEKEND.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
55
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
350 PM CDT MON AUG 18 2014
.SHORT TERM...
(Tonight and Tuesday)
Low confidence forecast across West Central Texas for the next 24
hours. Remnant Mesoscale Convective Vortex (MCV) continues to
remain nearly stationary across Sterling County early this
afternoon, and buried within a larger scale mid level shear axis
stretching across much of the area. Much like we saw on Sunday, as
the main morning area of showers and storms slowly winds down from
Abilene to Brownwood, more scattered convection is developing
along the periphery of the MCV where better heating is taking
place.
Biggest question in the forecast concerns tonight and Tuesday
rain chances. As the low level jet intensifies towards midnight,
expect to see another round of showers and storms form near the
center of the MCV and along its eastern flank. MCV is definitely
weaker today than it was yesterday, and should continue to slowly
wind down. How strong it remains tonight, where it ends up, and
what kind of storm coverage it can actually generate is highly
uncertain though. Models not a lot of help, with even the TTU WRF
and the HRRR models struggling in this highly mesoscale situation.
At this point, will bump pops to chance for most of the area,
knowing that some areas may miss out and others may see some
decent rainfall. Some of this area has seen rainfall totals in the
1 to 3 inch range, so if the rain can train over these areas, than
a flood threat becomes more pronounced. This will need to be
monitored through tonight.
07
.LONG TERM...
(Tuesday night through next Monday)
A mainly dry forecast expected for the extended period.
By Tuesday evening...the 500mb ridge that is currently centered
near Florida will expand farther west into Texas, pushing the
shear axis over the top of our CWA farther west as well. In
addition, by Tuesday night, 250mph ridging will move in over the
top of the region out of the southwest. These two factors point to
decreasing chances of precipitation overall for the area by
Tuesday night. However, we have left an area of slight chance PoPs
in for Tuesday evening. The combination of the previously
mentioned upper level shear axis and MCV is expected to result in
additional thunderstorm activity tomorrow afternoon. And although
these features are expected to be drifting to the west, there
could still be lingering activity for areas mainly south and west
of a Sterling City to San Angelo to Sonora line.
By Wednesday, upper level ridging will be in place across our
forecast area, effectively ending rain chances through the end of
the forecast period, and allowing temperatures to remain warm in
the mid to upper 90s for highs, and generally lower to mid 70s for
lows.
20
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 72 94 71 97 74 / 30 30 5 5 5
San Angelo 71 93 72 95 74 / 30 30 10 5 5
Junction 73 92 73 93 73 / 30 30 10 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
632 PM CDT TUE AUG 19 2014
.SHORT TERM...(TONIGHT THROUGH WEDNESDAY NIGHT)
ISSUED AT 252 PM CDT TUE AUG 19 2014
WATER VAPOR IMAGERY COUPLED WITH RAP 500MB ANALYSIS SHOWING A MID-
LEVEL LOW OVER WESTERN UPPER MICHIGAN. COLD POOL ALOFT ASSOCIATED
WITH THE LOW PRODUCING WIDESPREAD CUMULUS/STRATOCUMULUS FIELD ACROSS
THE FORECAST AREA WITH RADAR EVEN SHOWING A FEW SHOWERS POPPING UP
ACROSS NORTHERN MN INTO NORTHERN WI. OTHERWISE...TEMPERATURE ACROSS
THE ARX FORECAST AREA WERE IN THE 70-80 DEGREE RANGE.
FOR TONIGHT...COULD SEE A FEW SHOWERS NORTHEAST OF I-94 THIS EVENING
BUT THEN EXPECTING CLOUDS TO DIMINISH LATE IN THE EVENING AND
THROUGH THE OVERNIGHT HOURS AS A RIDGE OF HIGH PRESSURE MOVES
OVERHEAD. THIS WILL SET UP FAVORABLE FOG POTENTIAL OVERNIGHT/EARLY
WEDNESDAY MORNING...ESPECIALLY FAVORED RIVER VALLEY LOCATIONS.
THINKING AREAS SOUTHWEST OF I-94 WILL BE MOST IMPACTED WHERE
CONFIDENCE IS HIGHER FOR CLEARING SKY CONDITIONS EXISTS. HELD OFF ON
DENSE FOG ADVISORY FOR NOW BASED ON INPUT FROM SURROUNDING
OFFICES...BUT EVENING FORECASTER WILL HAVE TO MONITOR CLOSELY FOR
POSSIBLE FOG HEADLINE. LOOK FOR LOWS TONIGHT IN THE MIDDLE 50S TO
THE LOWER 60S.
AFTER AREAS OF MORNING FOG...PLAN ON THE RIDGE OF HIGH PRESSURE TO
KEEP THE FORECAST AREA DRY THROUGH WEDNESDAY. AN APPROACHING WARM
FRONT FROM THE CENTRAL PLAINS/MID-MISSISSIPPI RIVER VALLEY WILL
LIKELY SPARK A FEW SHOWERS AND THUNDERSTORMS...BUT PRETTY CONFIDENT
THESE WILL REMAIN SOUTH OF THE AREA. OTHERWISE...EXPECTING HIGH
TEMPERATURES TO TOP OFF IN THE MID 70S TO THE LOWER 80S.
LOOK FOR SHOWERS AND THUNDERSTORMS TO BECOME LIKELY BY LATE
WEDNESDAY NIGHT AS THE WARM FRONT CONTINUES TO APPROACH THE REGION.
ALL MODELS SHOW 850MB MOISTURE TRANSPORT INCREASING INTO/OVER THE
FRONT...WITH BEST AXIS OF MOISTURE PLUME REMAINING JUST WEST OF THE
FORECAST AREA. IN FACT...THE GFS/NAM SHOWING PRECIPITABLE WATER
VALUES SURGING INTO THE 1.5-2 INCH RANGE. THIS COULD LEAD TO SOME
LOCALIZED HEAVIER RAINFALL AS WARM CLOUD LAYER DEPTH INCREASE TO
AROUND 4KM BY MORNING. MAY NEED TO MONITOR THE POTENTIAL FOR A FEW
SEVERE THUNDERSTORMS WITH LARGE HAIL INITIALLY WITH THE INCOMING
CONVECTION AS NAM INDICATING 1-6KM MUCAPE IN THE 2500-3500J/KG RANGE
COUPLED WITH 25-35KT BULK SHEAR.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 252 PM CDT TUE AUG 19 2014
MODELS SHOWING THE WARM FRONT PUSHING NORTHEAST THROUGH THE AREA ON
THURSDAY FOR THE CONTINUED LIKELIHOOD OF SHOWERS AND THUNDERSTORMS.
MODELS ALSO SHOWING 850MB MOISTURE TRANSPORT WANING THROUGH THE
MORNING HOURS AND EVENTUAL CAPPING ALONG AND WEST OF THE MISSISSIPPI
DURING THE AFTERNOON HOURS. AS SUCH...DIVIDED POPS INTO
MORNING/AFTERNOON TIME PERIODS. STILL LOOKING AT THE POTENTIAL FOR
SOME LOCALIZED HEAVY RAINFALL THROUGH THE MORNING HOURS WITH
PRECIPITABLE WATER VALUES LINGERING IN THE 1.5 TO 2 INCH RANGE.
OTHERWISE...LOOK FOR SUBSTANTIALLY MORE HUMID CONDITIONS AS DEW
POINTS CREEP UP INTO THE LOWER 70S. THESE DEW POINTS COMBINED WITH
DAYTIME HIGHS WELL INTO THE 80S FOR MOST OF THE AREA ARE EXPECTED
TO PRODUCE HEAT INDICES IN THE 90 TO 100 DEGREE...HIGHEST ALONG AND
WEST/SOUTH OF THE MISSISSIPPI/WISCONSIN RIVERS.
FOR THURSDAY NIGHT THROUGH THE REST OF THE PERIOD...FORECAST
CONFIDENCE WANES FAIRLY RAPIDLY. MODEL CONSENSUS SHOWS A MID-LEVEL
RIDGE TRYING TO ESTABLISH ITSELF OVER THE CENTRAL CONUS.
HOWEVER...MESSY FLOW WITH MONSOONAL TAP WILL BE IN PLACE ACROSS THE
INTERMOUNTAIN/PLAINS REGION. TIMING OF THESE WAVES PRETTY UNCERTAIN
AT THIS TIME. AS SUCH...WILL KEEP LOW-MEDIUM RANGE
SHOWER/THUNDERSTORM CHANCES IN THROUGH THE PERIOD. TEMPERATURES
THROUGH THE PERIOD LOOK TO STAY AT OR A FEW DEGREES ABOVE NORMAL
THROUGH THE WEEKEND...WITH PERHAPS SOME COOLING EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 632 PM CDT TUE AUG 19 2014
FOCUS IS ON FOG POTENTIAL OVERNIGHT AT KRST/KLSE. DIURNAL CUMULUS
AND SCATTERED SHOWERS WILL SUBSIDE WITHIN THE NEXT FEW HOURS...AND
CANADIAN HIGH PRESSURE WILL BUILD IN FROM THE WEST. OVERALL VERY
FAVORABLE SETUP FOR FOG...WITH LIGHT WINDS THROUGH 2500 FT...AND
SUFFICIENT LOW LEVEL SATURATION COMBINED WITH THE RECENT RAINFALL
AND LIMITED MIXING TODAY. WILL CONTINUE TO ADVERTISE LIFR/IFR
CONDITIONS...PEAKING BETWEEN 10 AND 14Z. FOG WILL QUICKLY BURN OFF
MID MORNING...GIVING WAY TO SOME MID/HIGH LEVEL CLOUDS WITH THE
NEXT WEATHER SYSTEM.
&&
.HYDROLOGY...WEDNESDAY NIGHT INTO THURSDAY
ISSUED AT 252 PM CDT TUE AUG 19 2014
THERE IS THE LIKELIHOOD FOR SHOWERS AND THUNDERSTORMS WITH THE
POTENTIAL FOR HEAVY RAINFALL WEDNESDAY NIGHT INTO THURSDAY MORNING.
EXPECTING FAIRLY WIDESPREAD 1/4 TO 3/4 INCH RAINFALL WITH LOCALIZED
GREATER THAN 1 INCH AMOUNTS. THIS RAINFALL COMBINED WITH RECENT
POCKETS OF HEAVY RAINS ACROSS PORTIONS OF THE FORECAST AREA COULD
LEAD TO SOME LOCALIZED FLOODING CONCERNS. WILL KEEP A CLOSE EYE ON
LOCALIZED FLOODING CONCERN AND THE POTENTIAL FOR A FLASH FLOOD WATCH
HEADLINE WEDNESDAY NIGHT INTO THURSDAY MORNING ONCE CONFIDENCE
INCREASES ON EXACTLY WHERE THE HEAVIER RAINFALL WILL OCCUR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....ZT
HYDROLOGY...DAS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1257 PM CDT MON AUG 18 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT MON AUG 18 2014
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED TROUGHING FROM LAKE WINNIPEG INTO THE DAKOTAS AND RIDGING
OVER MICHIGAN. BETWEEN THESE TWO FEATURES...THERE WERE SHORTWAVES
NEAR LA CROSSE AND IN SOUTHEAST SOUTH DAKOTA. DPVA FROM THE FORMER
SHORTWAVE...COMBINED WITH A ZONE OF 850MB MOISTURE TRANSPORT WHICH
EXTENDED FROM NORTH CENTRAL IA INTO NORTH CENTRAL WI...HAS RESULTED
IN SCATTERED TO NUMEROUS CONVECTION OVER THE NORTHWEST HALF OF THE
FORECAST AREA. PRECIPITABLE WATER VALUES FROM THE RAP SHOW VALUES OF
1.5-1.8 INCHES IN GENERAL...HIGHEST WITHIN THE CONVECTION. THESE
HIGH VALUES HAS ALLOWED CONVECTION TO HAVE HEAVY RAINFALL RATES...
WITH UPWARDS OF 2 INCHES PER HOUR FROM THE ONE THAT WENT THROUGH THE
ROCHESTER AREA LATE LAST EVENING. TO THE WEST...ANOTHER ZONE OF 1.5-
1.8 INCH PRECIPITABLE WATER WAS PRESENT OVER FAR WESTERN MN...AHEAD
OF THE DAKOTAS UPPER TROUGH AND SOUTHEAST SOUTH DAKOTA SHORTWAVE.
DPVA FROM THESE FEATURES ACTING ON THE MOISTURE RESULTING IN
ISOLATED SHOWER AND STORM ACTIVITY IN FAR WESTERN MN TOO.
THE UPPER TROUGH FROM LAKE WINNIPEG INTO THE DAKOTAS REMAINS ON
TRACK TO MOVE INTO THE FORECAST AREA TONIGHT. PRETTY MUCH ALL DAY
TODAY THROUGH THE EVENING HOURS THE FORECAST AREA IS UNDER FALLING
500MB HEIGHTS. COMBINE THIS WITH A SERIES OF SHORTWAVES COMING
THROUGH FROM THE TROUGH SUCH AS THAT ONE IN SOUTHEAST SOUTH
DAKOTA...THE 1.5-1.8 INCH PRECIPITABLE WATER AIRMASS IN PLACE...AND
DAYTIME HEATING TO ADD EVEN MORE INSTABILITY...RESULTS IN A VERY
FAVORABLE SETUP FOR CONVECTION. THE MAJORITY OF THE FORECAST AREA
SHOULD SEE RAIN OVER THE NEXT 18 HOURS...WITH CORRIDORS OF HEAVIER
RAIN POSSIBLE DUE TO THE HIGH PRECIPITABLE WATER VALUES.
SPECIFICALLY TIMING THE WET AND DRY PERIODS IS VERY PROBLEMATIC...
BUT IN GENERAL IT SEEMS AS IF THERE COULD BE A DRY PERIOD AROUND MID-
MORNING. THIS WOULD CORRELATE WITH THE WEAKENING OF THE LOW LEVEL
JET AND A PERIOD OF SUBSIDENCE BETWEEN THE DEPARTING LA CROSSE
SHORTWAVE AND THE OTHER SHORTWAVE COMING IN FROM THE SIOUX FALLS.
WELL SEE. THE AFTERNOON INTO THE EARLY EVENING HOURS CERTAINLY BODE
WELL FOR CONVECTION WITH THE DAYTIME INSTABILITY HELP...THUS HIGHEST
CHANCES ARE CENTERED THEN. EVEN DURING THIS TIME FRAME...THERE COULD
BE 2-3 HOUR BREAKS BETWEEN ROUNDS OF CONVECTION. ANOTHER SPECIFIC
NOTE...IT WOULD APPEAR THE SOUTHEAST END OF THE FORECAST AREA MAY
NOT GET HIT WITH MUCH CONVECTION UNTIL LATE AFTERNOON OR THE EVENING
HOURS.
LOOK FOR THE CONVECTION TO PUSH OFF TO THE EAST LATE THIS
EVENING THROUGH THE OVERNIGHT HOURS...DUE TO A COMBINATION OF
SUBSIDENCE WORKING IN FROM THE WEST WITH THE TROUGH MOVING IN
PLACE...AS WELL AS LOSS OF DAYTIME HEATING DIMINISHING INSTABILITY.
A COLD FRONTAL PASSAGE LOOKS TO OCCUR AS WELL TONIGHT TO AID IN THE
DIMINISHING TREND.
REGARDING SEVERE WEATHER POTENTIAL...LOOKING AT SHEAR...WE MAY
NEED TO WATCH THE LATE AFTERNOON AND EVENING HOURS. AT 00Z...THE 0-
3KM SHEAR CLIMBS TO 25 KT AROUND I-90 AND 30-35 KT IN NORTHEAST
IOWA. IF CONVECTION EXISTS INTO THESE REGIONS...THEY MAY HAVE
SOME SEVERE WIND POTENTIAL. OTHERWISE...WARM CLOUD DEPTHS UPWARDS OF
3000-3500 METERS WILL RESULT IN HEAVY RAIN AS THE MAIN CONCERN. HAVE
NOT ISSUED ANY FLASH FLOOD WATCH GIVEN ANTECEDENT DRY
CONDITIONS...HOWEVER...LOCALIZED FLOOD ADVISORIES OR WARNINGS MAY
BE NEEDED...ESPECIALLY IN URBAN AREAS WHICH CANNOT HANDLE
HIGHER RAINFALL RATES.
THE CONVECTION AROUND TODAY MAKES FOR A TRICKY HIGH TEMPERATURE
FORECAST. 925MB TEMPS CLIMBING TO 19-22C ON AN INCREASING SOUTHWEST
WIND COULD ALLOW FOR HIGHS OF 80-85 UNDER THE FULL SUN.
HOWEVER...HAVE TO HOLD THESE BACK AS MUCH AS 5 DEGREES OR SO TO
ACCOUNT FOR CONVECTION. WARMEST READINGS ARE LIKELY IN THE SOUTHEAST
END WITH THE LONGEST DRY PERIOD EXPECTED. LOWS TONIGHT EXPECTED ON
THE MILD SIDE AGAIN WITH THE COLD FRONTAL PASSAGE MAKING THE BIGGER
IMPACT TO LOWERING TEMPERATURES.
WITH THE PRECIPITATION ENDING DURING THE NIGHT TIME HOURS...FOG
POTENTIAL NEEDS TO BE CONSIDERED. HOWEVER...IT APPEARS THERE SHOULD
BE A DECENT WEST TO NORTHWEST BREEZE IN THE WAKE OF THE COLD FRONTAL
PASSAGE TO KEEP THE AIR MIXED...PREVENTING FOG FORMATION.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 324 AM CDT MON AUG 18 2014
TUESDAY INTO TUESDAY NIGHT...MODELS TAKE THEIR SWEET TIME IN GETTING
THE UPPER TROUGH OUT OF THE REGION. HOWEVER...IT DOES LOOK TO GET A
DECENT PUSH EAST LATE TUESDAY NIGHT...RESPONDING TO UPPER RIDGING
BEING FORCED TO BUILD UP OVER THE DAKOTAS INTO MN. WHATS
INTERESTING DURING THIS TIME PERIOD IS SUGGESTIONS OF A SECONDARY
COLD FRONT DROPPING SOUTH THROUGH THE AREA DURING THE AFTERNOON AND
EVENING...CONNECTED WITH ANOTHER SHORTWAVE COMING THROUGH THE
TROUGH. HAVE MAINTAINED SOME PRECIPITATION CHANCES...HIGHEST OVER
NORTH CENTRAL WISCONSIN UNDER THE COOLER AIR ALOFT AND HIGHEST
PRECIPITABLE WATER. MUCH OF THE PRECIPITATION SHOULD END BY LATE
EVENING WITH LOSS OF DAYTIME HEATING AND UPPER TROUGH BEGINNING TO
PULL AWAY. IT SHOULD BE NOTED THE RAINFALL RATES ON TUESDAY DO NOT
LOOK NEARLY AS HIGH TODAY...A RESULT OF THE PRECIPITABLE WATER
VALUES ONLY IN THE 1-1.5 RANGE. LATE TUESDAY NIGHT...WE SHOULD GET A
SURFACE RIDGE OF HIGH PRESSURE TO BUILD INTO THE WESTERN 2/3 OF THE
REGION. SKIES SHOULD CLEAR AND WINDS WILL RELAX WITH THE RIDGE
COMING IN...SETTING UP CONDITIONS FAVORABLE FOR SOME FOG TO FORM.
DETAILS ON THE EXPANSE AND THICKNESS OF THE FOG WILL DEPEND EXACTLY
ON THE TIMING OF THE RIDGE COMING IN. DESPITE THE COLD FRONTAL
PASSAGE...925MB TEMPS ARE PROGGED PRETTY SIMILAR ON TUESDAY TO
TODAY. THE SOUTHERN FORECAST AREA SHOULD BE WARMEST GIVEN BETTER
MIXING POTENTIAL.
FOR WEDNESDAY INTO THURSDAY...MODELS BRING THAT UPPER RIDGING OVER
MN INTO THE FORECAST AREA. IT WOULD APPEAR ENOUGH SUBSIDENCE SHOULD
BE IN PLACE PRIOR TO THE RIDGE BUILDING IN TO YIELD A DRY DAY
WEDNESDAY. ADDITIONALLY...THE MAIN WARM FRONTAL BOUNDARY LOOKS TO BE
WELL TO THE SOUTH...ONLY NEAR THE MISSOURI/IOWA BORDER AT 00Z
THURSDAY. HOWEVER...THIS BOUNDARY LOOKS TO SURGE NORTHWARD TOWARDS
THE FORECAST AREA WEDNESDAY NIGHT...AND POSSIBLY COMPLETELY THROUGH
ON THURSDAY. A DECENT PUSH OF 850MB MOISTURE TRANSPORT INTO THE
BOUNDARY WILL INITIATE ELEVATED CONVECTION OVER THE SOUTHWEST
2/3 OF THE AREA. AGAIN HEAVY RAIN LOOKS TO BE A BIG CONCERN AS
PRECIPITABLE WATER CLIMBS BACK UP TOWARDS 2 INCHES...ALONG WITH A
FEED OF INSTABILITY INTO THE CONVECTION FROM THE LOW LEVEL JET...AND
POTENTIAL TO BE IN THE RIGHT ENTRANCE REGION OF A JET STREAK OVER
LOWER MICHIGAN. RIGHT NOW IT APPEARS THE BOUNDARY SHOULD CONTINUE TO
LIFT NORTHWARD...HELPING TO PREVENT A WIDER FLASH FLOOD THREAT...BUT
NEEDS TO BE WATCHED CLOSELY. ADDITIONALLY...CANNOT RULE OUT SOME
SEVERE WIND POTENTIAL FROM THE CONVECTION. CONVECTION SHOULD
DIMINISH LATE THURSDAY MORNING THROUGH THE AFTERNOON HOURS WITH THE
WEAKENING OF THE LOW LEVEL JET...AND AS CAPPING COMES IN ALOFT.
TEMPERATURES AFTER HOVERING IN THE MID 70S TO LOW 80S THROUGH
WEDNESDAY COULD MAKE A MAJOR BOOST ON THURSDAY. THERE IS POTENTIAL
ACCORDING TO THE 18.00Z ECMWF FOR LOCATIONS ALONG/WEST OF THE MS
RIVER TO GET CLOSE TO 90...ALL DEPENDING ON SUN AND WARM FRONTAL
BOUNDARY TRACK.
FOR THURSDAY NIGHT THROUGH THE WEEKEND...THE 500MB PATTERN FEATURES
UPPER RIDGING TO BEGIN THE PERIOD OVER THE AREA WHILE TROUGHING
EXISTS ACROSS THE PACIFIC NORTHWEST. MODELS ARE IN BETTER AGREEMENT
TODAY THAN YESTERDAY HANDLING THIS TROUGH...AND IT APPEARS SOME
OF THIS TROUGH WILL PUSH EAST INTO THE WEEKEND AND HELP SHIFT THE
RIDGE EASTWARD. THIS TRANSLATES INTO A STORM SYSTEM TO AFFECT THE
REGION FOR FRIDAY THROUGH THE WEEKEND. THE ASSOCIATED WARM FRONT
LOOKS TO LIFT INTO THE REGION ON FRIDAY...WHICH MAY OR MAY NOT
CONVECT DEPENDING ON CAPPING. A COLD FRONTAL PASSAGE COULD OCCUR ON
SATURDAY...FOLLOWED BY A LOW RIDING UP ALONG THE FRONT ON SUNDAY.
CONVECTION IS EASILY POSSIBLE ON BOTH OF THESE FEATURES.
THEREFORE...CHANCES OF SHOWERS AND THUNDERSTORMS LITTER MUCH OF THE
EXTENDED. PRIOR TO THE COLD FRONTAL PASSAGE...925MB TEMPS LOOK TO
RANGE FROM 22-26C...SUPPORTIVE OF 80S TO POSSIBLY 90...DEPENDING ON
AMOUNT OF SUN. AIRMASS APPEARS HUMID TOO. COOLER AIR THEN FILTERS
IN FOR SUNDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY MORNING)
ISSUED AT 1256 PM CDT MON AUG 18 2014
TWO SHORT WAVE TROUGHS WILL MOVE THROUGH THE AREA DURING THE NEXT
24 HOURS. EACH OF THESE WILL BE RESPONSIBLE FOR ROUNDS OF SHOWERS
AND THUNDERSTORMS AT THE TAF SITES. THE FIRST ROUND LOOKS TO
AFFECT THE TAF SITES BETWEEN 18.19Z AND 18.23Z...AND THEN ANOTHER
ROUND BETWEEN 19.01Z AND 19.04Z. CEILINGS WILL BE IN THE 2500 TO
3500 FOOT RANGE THROUGH 19.08Z...AND THEN BECOME LIFR/IFR THROUGH
19.15Z...AND THEN MVFR AGAIN. A FEW OF THE NAM AND SREF SOLUTIONS
ARE INICATING THAT THERE COULD BE THE POTENTIAL FOR SOME DENSE FOG
TONIGHT. HOWEVER WITH 15 TO 25 KNOTS ABOVE 950 MB...THINKING THAT
THIS MAY JUST END UP BEING MORE STRATUS THAN FOG. HOWEVER...STILL
WENT WITH MVFR FOG.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
627 AM CDT MON AUG 18 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT MON AUG 18 2014
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED TROUGHING FROM LAKE WINNIPEG INTO THE DAKOTAS AND RIDGING
OVER MICHIGAN. BETWEEN THESE TWO FEATURES...THERE WERE SHORTWAVES
NEAR LA CROSSE AND IN SOUTHEAST SOUTH DAKOTA. DPVA FROM THE FORMER
SHORTWAVE...COMBINED WITH A ZONE OF 850MB MOISTURE TRANSPORT WHICH
EXTENDED FROM NORTH CENTRAL IA INTO NORTH CENTRAL WI...HAS RESULTED
IN SCATTERED TO NUMEROUS CONVECTION OVER THE NORTHWEST HALF OF THE
FORECAST AREA. PRECIPITABLE WATER VALUES FROM THE RAP SHOW VALUES OF
1.5-1.8 INCHES IN GENERAL...HIGHEST WITHIN THE CONVECTION. THESE
HIGH VALUES HAS ALLOWED CONVECTION TO HAVE HEAVY RAINFALL RATES...
WITH UPWARDS OF 2 INCHES PER HOUR FROM THE ONE THAT WENT THROUGH THE
ROCHESTER AREA LATE LAST EVENING. TO THE WEST...ANOTHER ZONE OF 1.5-
1.8 INCH PRECIPITABLE WATER WAS PRESENT OVER FAR WESTERN MN...AHEAD
OF THE DAKOTAS UPPER TROUGH AND SOUTHEAST SOUTH DAKOTA SHORTWAVE.
DPVA FROM THESE FEATURES ACTING ON THE MOISTURE RESULTING IN
ISOLATED SHOWER AND STORM ACTIVITY IN FAR WESTERN MN TOO.
THE UPPER TROUGH FROM LAKE WINNIPEG INTO THE DAKOTAS REMAINS ON
TRACK TO MOVE INTO THE FORECAST AREA TONIGHT. PRETTY MUCH ALL DAY
TODAY THROUGH THE EVENING HOURS THE FORECAST AREA IS UNDER FALLING
500MB HEIGHTS. COMBINE THIS WITH A SERIES OF SHORTWAVES COMING
THROUGH FROM THE TROUGH SUCH AS THAT ONE IN SOUTHEAST SOUTH
DAKOTA...THE 1.5-1.8 INCH PRECIPITABLE WATER AIRMASS IN PLACE...AND
DAYTIME HEATING TO ADD EVEN MORE INSTABILITY...RESULTS IN A VERY
FAVORABLE SETUP FOR CONVECTION. THE MAJORITY OF THE FORECAST AREA
SHOULD SEE RAIN OVER THE NEXT 18 HOURS...WITH CORRIDORS OF HEAVIER
RAIN POSSIBLE DUE TO THE HIGH PRECIPITABLE WATER VALUES.
SPECIFICALLY TIMING THE WET AND DRY PERIODS IS VERY PROBLEMATIC...
BUT IN GENERAL IT SEEMS AS IF THERE COULD BE A DRY PERIOD AROUND MID-
MORNING. THIS WOULD CORRELATE WITH THE WEAKENING OF THE LOW LEVEL
JET AND A PERIOD OF SUBSIDENCE BETWEEN THE DEPARTING LA CROSSE
SHORTWAVE AND THE OTHER SHORTWAVE COMING IN FROM THE SIOUX FALLS.
WELL SEE. THE AFTERNOON INTO THE EARLY EVENING HOURS CERTAINLY BODE
WELL FOR CONVECTION WITH THE DAYTIME INSTABILITY HELP...THUS HIGHEST
CHANCES ARE CENTERED THEN. EVEN DURING THIS TIME FRAME...THERE COULD
BE 2-3 HOUR BREAKS BETWEEN ROUNDS OF CONVECTION. ANOTHER SPECIFIC
NOTE...IT WOULD APPEAR THE SOUTHEAST END OF THE FORECAST AREA MAY
NOT GET HIT WITH MUCH CONVECTION UNTIL LATE AFTERNOON OR THE EVENING
HOURS.
LOOK FOR THE CONVECTION TO PUSH OFF TO THE EAST LATE THIS
EVENING THROUGH THE OVERNIGHT HOURS...DUE TO A COMBINATION OF
SUBSIDENCE WORKING IN FROM THE WEST WITH THE TROUGH MOVING IN
PLACE...AS WELL AS LOSS OF DAYTIME HEATING DIMINISHING INSTABILITY.
A COLD FRONTAL PASSAGE LOOKS TO OCCUR AS WELL TONIGHT TO AID IN THE
DIMINISHING TREND.
REGARDING SEVERE WEATHER POTENTIAL...LOOKING AT SHEAR...WE MAY
NEED TO WATCH THE LATE AFTERNOON AND EVENING HOURS. AT 00Z...THE 0-
3KM SHEAR CLIMBS TO 25 KT AROUND I-90 AND 30-35 KT IN NORTHEAST
IOWA. IF CONVECTION EXISTS INTO THESE REGIONS...THEY MAY HAVE
SOME SEVERE WIND POTENTIAL. OTHERWISE...WARM CLOUD DEPTHS UPWARDS OF
3000-3500 METERS WILL RESULT IN HEAVY RAIN AS THE MAIN CONCERN. HAVE
NOT ISSUED ANY FLASH FLOOD WATCH GIVEN ANTECEDENT DRY
CONDITIONS...HOWEVER...LOCALIZED FLOOD ADVISORIES OR WARNINGS MAY
BE NEEDED...ESPECIALLY IN URBAN AREAS WHICH CANNOT HANDLE
HIGHER RAINFALL RATES.
THE CONVECTION AROUND TODAY MAKES FOR A TRICKY HIGH TEMPERATURE
FORECAST. 925MB TEMPS CLIMBING TO 19-22C ON AN INCREASING SOUTHWEST
WIND COULD ALLOW FOR HIGHS OF 80-85 UNDER THE FULL SUN.
HOWEVER...HAVE TO HOLD THESE BACK AS MUCH AS 5 DEGREES OR SO TO
ACCOUNT FOR CONVECTION. WARMEST READINGS ARE LIKELY IN THE SOUTHEAST
END WITH THE LONGEST DRY PERIOD EXPECTED. LOWS TONIGHT EXPECTED ON
THE MILD SIDE AGAIN WITH THE COLD FRONTAL PASSAGE MAKING THE BIGGER
IMPACT TO LOWERING TEMPERATURES.
WITH THE PRECIPITATION ENDING DURING THE NIGHT TIME HOURS...FOG
POTENTIAL NEEDS TO BE CONSIDERED. HOWEVER...IT APPEARS THERE SHOULD
BE A DECENT WEST TO NORTHWEST BREEZE IN THE WAKE OF THE COLD FRONTAL
PASSAGE TO KEEP THE AIR MIXED...PREVENTING FOG FORMATION.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 324 AM CDT MON AUG 18 2014
TUESDAY INTO TUESDAY NIGHT...MODELS TAKE THEIR SWEET TIME IN GETTING
THE UPPER TROUGH OUT OF THE REGION. HOWEVER...IT DOES LOOK TO GET A
DECENT PUSH EAST LATE TUESDAY NIGHT...RESPONDING TO UPPER RIDGING
BEING FORCED TO BUILD UP OVER THE DAKOTAS INTO MN. WHATS
INTERESTING DURING THIS TIME PERIOD IS SUGGESTIONS OF A SECONDARY
COLD FRONT DROPPING SOUTH THROUGH THE AREA DURING THE AFTERNOON AND
EVENING...CONNECTED WITH ANOTHER SHORTWAVE COMING THROUGH THE
TROUGH. HAVE MAINTAINED SOME PRECIPITATION CHANCES...HIGHEST OVER
NORTH CENTRAL WISCONSIN UNDER THE COOLER AIR ALOFT AND HIGHEST
PRECIPITABLE WATER. MUCH OF THE PRECIPITATION SHOULD END BY LATE
EVENING WITH LOSS OF DAYTIME HEATING AND UPPER TROUGH BEGINNING TO
PULL AWAY. IT SHOULD BE NOTED THE RAINFALL RATES ON TUESDAY DO NOT
LOOK NEARLY AS HIGH TODAY...A RESULT OF THE PRECIPITABLE WATER
VALUES ONLY IN THE 1-1.5 RANGE. LATE TUESDAY NIGHT...WE SHOULD GET A
SURFACE RIDGE OF HIGH PRESSURE TO BUILD INTO THE WESTERN 2/3 OF THE
REGION. SKIES SHOULD CLEAR AND WINDS WILL RELAX WITH THE RIDGE
COMING IN...SETTING UP CONDITIONS FAVORABLE FOR SOME FOG TO FORM.
DETAILS ON THE EXPANSE AND THICKNESS OF THE FOG WILL DEPEND EXACTLY
ON THE TIMING OF THE RIDGE COMING IN. DESPITE THE COLD FRONTAL
PASSAGE...925MB TEMPS ARE PROGGED PRETTY SIMILAR ON TUESDAY TO
TODAY. THE SOUTHERN FORECAST AREA SHOULD BE WARMEST GIVEN BETTER
MIXING POTENTIAL.
FOR WEDNESDAY INTO THURSDAY...MODELS BRING THAT UPPER RIDGING OVER
MN INTO THE FORECAST AREA. IT WOULD APPEAR ENOUGH SUBSIDENCE SHOULD
BE IN PLACE PRIOR TO THE RIDGE BUILDING IN TO YIELD A DRY DAY
WEDNESDAY. ADDITIONALLY...THE MAIN WARM FRONTAL BOUNDARY LOOKS TO BE
WELL TO THE SOUTH...ONLY NEAR THE MISSOURI/IOWA BORDER AT 00Z
THURSDAY. HOWEVER...THIS BOUNDARY LOOKS TO SURGE NORTHWARD TOWARDS
THE FORECAST AREA WEDNESDAY NIGHT...AND POSSIBLY COMPLETELY THROUGH
ON THURSDAY. A DECENT PUSH OF 850MB MOISTURE TRANSPORT INTO THE
BOUNDARY WILL INITIATE ELEVATED CONVECTION OVER THE SOUTHWEST
2/3 OF THE AREA. AGAIN HEAVY RAIN LOOKS TO BE A BIG CONCERN AS
PRECIPITABLE WATER CLIMBS BACK UP TOWARDS 2 INCHES...ALONG WITH A
FEED OF INSTABILITY INTO THE CONVECTION FROM THE LOW LEVEL JET...AND
POTENTIAL TO BE IN THE RIGHT ENTRANCE REGION OF A JET STREAK OVER
LOWER MICHIGAN. RIGHT NOW IT APPEARS THE BOUNDARY SHOULD CONTINUE TO
LIFT NORTHWARD...HELPING TO PREVENT A WIDER FLASH FLOOD THREAT...BUT
NEEDS TO BE WATCHED CLOSELY. ADDITIONALLY...CANNOT RULE OUT SOME
SEVERE WIND POTENTIAL FROM THE CONVECTION. CONVECTION SHOULD
DIMINISH LATE THURSDAY MORNING THROUGH THE AFTERNOON HOURS WITH THE
WEAKENING OF THE LOW LEVEL JET...AND AS CAPPING COMES IN ALOFT.
TEMPERATURES AFTER HOVERING IN THE MID 70S TO LOW 80S THROUGH
WEDNESDAY COULD MAKE A MAJOR BOOST ON THURSDAY. THERE IS POTENTIAL
ACCORDING TO THE 18.00Z ECMWF FOR LOCATIONS ALONG/WEST OF THE MS
RIVER TO GET CLOSE TO 90...ALL DEPENDING ON SUN AND WARM FRONTAL
BOUNDARY TRACK.
FOR THURSDAY NIGHT THROUGH THE WEEKEND...THE 500MB PATTERN FEATURES
UPPER RIDGING TO BEGIN THE PERIOD OVER THE AREA WHILE TROUGHING
EXISTS ACROSS THE PACIFIC NORTHWEST. MODELS ARE IN BETTER AGREEMENT
TODAY THAN YESTERDAY HANDLING THIS TROUGH...AND IT APPEARS SOME
OF THIS TROUGH WILL PUSH EAST INTO THE WEEKEND AND HELP SHIFT THE
RIDGE EASTWARD. THIS TRANSLATES INTO A STORM SYSTEM TO AFFECT THE
REGION FOR FRIDAY THROUGH THE WEEKEND. THE ASSOCIATED WARM FRONT
LOOKS TO LIFT INTO THE REGION ON FRIDAY...WHICH MAY OR MAY NOT
CONVECT DEPENDING ON CAPPING. A COLD FRONTAL PASSAGE COULD OCCUR ON
SATURDAY...FOLLOWED BY A LOW RIDING UP ALONG THE FRONT ON SUNDAY.
CONVECTION IS EASILY POSSIBLE ON BOTH OF THESE FEATURES.
THEREFORE...CHANCES OF SHOWERS AND THUNDERSTORMS LITTER MUCH OF THE
EXTENDED. PRIOR TO THE COLD FRONTAL PASSAGE...925MB TEMPS LOOK TO
RANGE FROM 22-26C...SUPPORTIVE OF 80S TO POSSIBLY 90...DEPENDING ON
AMOUNT OF SUN. AIRMASS APPEARS HUMID TOO. COOLER AIR THEN FILTERS
IN FOR SUNDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 627 AM CDT MON AUG 18 2014
PERIODS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED AT THE TAF SITES
FROM LATE THIS MORNING INTO THE AFTERNOON HOURS. IFR CONDITIONS
ARE POSSIBLE IN THE HEAVIER ACTIVITY THIS AFTERNOON. HAVE TRIED TO
TIME THE PERIODS OF HIGHEST CONFIDENCE FOR THE THUNDERSTORM
ACTIVITY AT THE TAF SITES BUT GIVEN THE UNSTABLE AIRMASS OVER THE
REGION AND THE BROAD FORCING MOVING IN...THE THUNDERSTORMS WILL
LIKELY BECOME WIDESPREAD AND TIMING THE STORMS THROUGH THE TAF
SITES WILL BE CHALLENGING ESPECIALLY LATE THIS AFTERNOON INTO THIS
EVENING. CONDITIONS SHOULD GRADUALLY IMPROVE TO VFR LATE THIS
EVENING INTO THE OVERNIGHT HOURS. FORECAST GUIDANCE IS HINTING AT
SOME FOG TONIGHT BUT LOOKING AT THE FORECAST SOUNDINGS...THE
WEST/NORTHWEST FLOW JUST ABOVE THE SURFACE SHOULD PROMOTE ENOUGH
MIXING TO LIMIT FOG DEVELOPMENT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
324 AM CDT MON AUG 18 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT MON AUG 18 2014
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED TROUGHING FROM LAKE WINNIPEG INTO THE DAKOTAS AND RIDGING
OVER MICHIGAN. BETWEEN THESE TWO FEATURES...THERE WERE SHORTWAVES
NEAR LA CROSSE AND IN SOUTHEAST SOUTH DAKOTA. DPVA FROM THE FORMER
SHORTWAVE...COMBINED WITH A ZONE OF 850MB MOISTURE TRANSPORT WHICH
EXTENDED FROM NORTH CENTRAL IA INTO NORTH CENTRAL WI...HAS RESULTED
IN SCATTERED TO NUMEROUS CONVECTION OVER THE NORTHWEST HALF OF THE
FORECAST AREA. PRECIPITABLE WATER VALUES FROM THE RAP SHOW VALUES OF
1.5-1.8 INCHES IN GENERAL...HIGHEST WITHIN THE CONVECTION. THESE
HIGH VALUES HAS ALLOWED CONVECTION TO HAVE HEAVY RAINFALL RATES...
WITH UPWARDS OF 2 INCHES PER HOUR FROM THE ONE THAT WENT THROUGH THE
ROCHESTER AREA LATE LAST EVENING. TO THE WEST...ANOTHER ZONE OF 1.5-
1.8 INCH PRECIPITABLE WATER WAS PRESENT OVER FAR WESTERN MN...AHEAD
OF THE DAKOTAS UPPER TROUGH AND SOUTHEAST SOUTH DAKOTA SHORTWAVE.
DPVA FROM THESE FEATURES ACTING ON THE MOISTURE RESULTING IN
ISOLATED SHOWER AND STORM ACTIVITY IN FAR WESTERN MN TOO.
THE UPPER TROUGH FROM LAKE WINNIPEG INTO THE DAKOTAS REMAINS ON
TRACK TO MOVE INTO THE FORECAST AREA TONIGHT. PRETTY MUCH ALL DAY
TODAY THROUGH THE EVENING HOURS THE FORECAST AREA IS UNDER FALLING
500MB HEIGHTS. COMBINE THIS WITH A SERIES OF SHORTWAVES COMING
THROUGH FROM THE TROUGH SUCH AS THAT ONE IN SOUTHEAST SOUTH
DAKOTA...THE 1.5-1.8 INCH PRECIPITABLE WATER AIRMASS IN PLACE...AND
DAYTIME HEATING TO ADD EVEN MORE INSTABILITY...RESULTS IN A VERY
FAVORABLE SETUP FOR CONVECTION. THE MAJORITY OF THE FORECAST AREA
SHOULD SEE RAIN OVER THE NEXT 18 HOURS...WITH CORRIDORS OF HEAVIER
RAIN POSSIBLE DUE TO THE HIGH PRECIPITABLE WATER VALUES.
SPECIFICALLY TIMING THE WET AND DRY PERIODS IS VERY PROBLEMATIC...
BUT IN GENERAL IT SEEMS AS IF THERE COULD BE A DRY PERIOD AROUND MID-
MORNING. THIS WOULD CORRELATE WITH THE WEAKENING OF THE LOW LEVEL
JET AND A PERIOD OF SUBSIDENCE BETWEEN THE DEPARTING LA CROSSE
SHORTWAVE AND THE OTHER SHORTWAVE COMING IN FROM THE SIOUX FALLS.
WELL SEE. THE AFTERNOON INTO THE EARLY EVENING HOURS CERTAINLY BODE
WELL FOR CONVECTION WITH THE DAYTIME INSTABILITY HELP...THUS HIGHEST
CHANCES ARE CENTERED THEN. EVEN DURING THIS TIME FRAME...THERE COULD
BE 2-3 HOUR BREAKS BETWEEN ROUNDS OF CONVECTION. ANOTHER SPECIFIC
NOTE...IT WOULD APPEAR THE SOUTHEAST END OF THE FORECAST AREA MAY
NOT GET HIT WITH MUCH CONVECTION UNTIL LATE AFTERNOON OR THE EVENING
HOURS.
LOOK FOR THE CONVECTION TO PUSH OFF TO THE EAST LATE THIS
EVENING THROUGH THE OVERNIGHT HOURS...DUE TO A COMBINATION OF
SUBSIDENCE WORKING IN FROM THE WEST WITH THE TROUGH MOVING IN
PLACE...AS WELL AS LOSS OF DAYTIME HEATING DIMINISHING INSTABILITY.
A COLD FRONTAL PASSAGE LOOKS TO OCCUR AS WELL TONIGHT TO AID IN THE
DIMINISHING TREND.
REGARDING SEVERE WEATHER POTENTIAL...LOOKING AT SHEAR...WE MAY
NEED TO WATCH THE LATE AFTERNOON AND EVENING HOURS. AT 00Z...THE 0-
3KM SHEAR CLIMBS TO 25 KT AROUND I-90 AND 30-35 KT IN NORTHEAST
IOWA. IF CONVECTION EXISTS INTO THESE REGIONS...THEY MAY HAVE
SOME SEVERE WIND POTENTIAL. OTHERWISE...WARM CLOUD DEPTHS UPWARDS OF
3000-3500 METERS WILL RESULT IN HEAVY RAIN AS THE MAIN CONCERN. HAVE
NOT ISSUED ANY FLASH FLOOD WATCH GIVEN ANTECEDENT DRY
CONDITIONS...HOWEVER...LOCALIZED FLOOD ADVISORIES OR WARNINGS MAY
BE NEEDED...ESPECIALLY IN URBAN AREAS WHICH CANNOT HANDLE
HIGHER RAINFALL RATES.
THE CONVECTION AROUND TODAY MAKES FOR A TRICKY HIGH TEMPERATURE
FORECAST. 925MB TEMPS CLIMBING TO 19-22C ON AN INCREASING SOUTHWEST
WIND COULD ALLOW FOR HIGHS OF 80-85 UNDER THE FULL SUN.
HOWEVER...HAVE TO HOLD THESE BACK AS MUCH AS 5 DEGREES OR SO TO
ACCOUNT FOR CONVECTION. WARMEST READINGS ARE LIKELY IN THE SOUTHEAST
END WITH THE LONGEST DRY PERIOD EXPECTED. LOWS TONIGHT EXPECTED ON
THE MILD SIDE AGAIN WITH THE COLD FRONTAL PASSAGE MAKING THE BIGGER
IMPACT TO LOWERING TEMPERATURES.
WITH THE PRECIPITATION ENDING DURING THE NIGHT TIME HOURS...FOG
POTENTIAL NEEDS TO BE CONSIDERED. HOWEVER...IT APPEARS THERE SHOULD
BE A DECENT WEST TO NORTHWEST BREEZE IN THE WAKE OF THE COLD FRONTAL
PASSAGE TO KEEP THE AIR MIXED...PREVENTING FOG FORMATION.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 324 AM CDT MON AUG 18 2014
TUESDAY INTO TUESDAY NIGHT...MODELS TAKE THEIR SWEET TIME IN GETTING
THE UPPER TROUGH OUT OF THE REGION. HOWEVER...IT DOES LOOK TO GET A
DECENT PUSH EAST LATE TUESDAY NIGHT...RESPONDING TO UPPER RIDGING
BEING FORCED TO BUILD UP OVER THE DAKOTAS INTO MN. WHATS
INTERESTING DURING THIS TIME PERIOD IS SUGGESTIONS OF A SECONDARY
COLD FRONT DROPPING SOUTH THROUGH THE AREA DURING THE AFTERNOON AND
EVENING...CONNECTED WITH ANOTHER SHORTWAVE COMING THROUGH THE
TROUGH. HAVE MAINTAINED SOME PRECIPITATION CHANCES...HIGHEST OVER
NORTH CENTRAL WISCONSIN UNDER THE COOLER AIR ALOFT AND HIGHEST
PRECIPITABLE WATER. MUCH OF THE PRECIPITATION SHOULD END BY LATE
EVENING WITH LOSS OF DAYTIME HEATING AND UPPER TROUGH BEGINNING TO
PULL AWAY. IT SHOULD BE NOTED THE RAINFALL RATES ON TUESDAY DO NOT
LOOK NEARLY AS HIGH TODAY...A RESULT OF THE PRECIPITABLE WATER
VALUES ONLY IN THE 1-1.5 RANGE. LATE TUESDAY NIGHT...WE SHOULD GET A
SURFACE RIDGE OF HIGH PRESSURE TO BUILD INTO THE WESTERN 2/3 OF THE
REGION. SKIES SHOULD CLEAR AND WINDS WILL RELAX WITH THE RIDGE
COMING IN...SETTING UP CONDITIONS FAVORABLE FOR SOME FOG TO FORM.
DETAILS ON THE EXPANSE AND THICKNESS OF THE FOG WILL DEPEND EXACTLY
ON THE TIMING OF THE RIDGE COMING IN. DESPITE THE COLD FRONTAL
PASSAGE...925MB TEMPS ARE PROGGED PRETTY SIMILAR ON TUESDAY TO
TODAY. THE SOUTHERN FORECAST AREA SHOULD BE WARMEST GIVEN BETTER
MIXING POTENTIAL.
FOR WEDNESDAY INTO THURSDAY...MODELS BRING THAT UPPER RIDGING OVER
MN INTO THE FORECAST AREA. IT WOULD APPEAR ENOUGH SUBSIDENCE SHOULD
BE IN PLACE PRIOR TO THE RIDGE BUILDING IN TO YIELD A DRY DAY
WEDNESDAY. ADDITIONALLY...THE MAIN WARM FRONTAL BOUNDARY LOOKS TO BE
WELL TO THE SOUTH...ONLY NEAR THE MISSOURI/IOWA BORDER AT 00Z
THURSDAY. HOWEVER...THIS BOUNDARY LOOKS TO SURGE NORTHWARD TOWARDS
THE FORECAST AREA WEDNESDAY NIGHT...AND POSSIBLY COMPLETELY THROUGH
ON THURSDAY. A DECENT PUSH OF 850MB MOISTURE TRANSPORT INTO THE
BOUNDARY WILL INITIATE ELEVATED CONVECTION OVER THE SOUTHWEST
2/3 OF THE AREA. AGAIN HEAVY RAIN LOOKS TO BE A BIG CONCERN AS
PRECIPITABLE WATER CLIMBS BACK UP TOWARDS 2 INCHES...ALONG WITH A
FEED OF INSTABILITY INTO THE CONVECTION FROM THE LOW LEVEL JET...AND
POTENTIAL TO BE IN THE RIGHT ENTRANCE REGION OF A JET STREAK OVER
LOWER MICHIGAN. RIGHT NOW IT APPEARS THE BOUNDARY SHOULD CONTINUE TO
LIFT NORTHWARD...HELPING TO PREVENT A WIDER FLASH FLOOD THREAT...BUT
NEEDS TO BE WATCHED CLOSELY. ADDITIONALLY...CANNOT RULE OUT SOME
SEVERE WIND POTENTIAL FROM THE CONVECTION. CONVECTION SHOULD
DIMINISH LATE THURSDAY MORNING THROUGH THE AFTERNOON HOURS WITH THE
WEAKENING OF THE LOW LEVEL JET...AND AS CAPPING COMES IN ALOFT.
TEMPERATURES AFTER HOVERING IN THE MID 70S TO LOW 80S THROUGH
WEDNESDAY COULD MAKE A MAJOR BOOST ON THURSDAY. THERE IS POTENTIAL
ACCORDING TO THE 18.00Z ECMWF FOR LOCATIONS ALONG/WEST OF THE MS
RIVER TO GET CLOSE TO 90...ALL DEPENDING ON SUN AND WARM FRONTAL
BOUNDARY TRACK.
FOR THURSDAY NIGHT THROUGH THE WEEKEND...THE 500MB PATTERN FEATURES
UPPER RIDGING TO BEGIN THE PERIOD OVER THE AREA WHILE TROUGHING
EXISTS ACROSS THE PACIFIC NORTHWEST. MODELS ARE IN BETTER AGREEMENT
TODAY THAN YESTERDAY HANDLING THIS TROUGH...AND IT APPEARS SOME
OF THIS TROUGH WILL PUSH EAST INTO THE WEEKEND AND HELP SHIFT THE
RIDGE EASTWARD. THIS TRANSLATES INTO A STORM SYSTEM TO AFFECT THE
REGION FOR FRIDAY THROUGH THE WEEKEND. THE ASSOCIATED WARM FRONT
LOOKS TO LIFT INTO THE REGION ON FRIDAY...WHICH MAY OR MAY NOT
CONVECT DEPENDING ON CAPPING. A COLD FRONTAL PASSAGE COULD OCCUR ON
SATURDAY...FOLLOWED BY A LOW RIDING UP ALONG THE FRONT ON SUNDAY.
CONVECTION IS EASILY POSSIBLE ON BOTH OF THESE FEATURES.
THEREFORE...CHANCES OF SHOWERS AND THUNDERSTORMS LITTER MUCH OF THE
EXTENDED. PRIOR TO THE COLD FRONTAL PASSAGE...925MB TEMPS LOOK TO
RANGE FROM 22-26C...SUPPORTIVE OF 80S TO POSSIBLY 90...DEPENDING ON
AMOUNT OF SUN. AIRMASS APPEARS HUMID TOO. COOLER AIR THEN FILTERS
IN FOR SUNDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1139 PM CDT SUN AUG 17 2014
SHOWERS AND STORMS CONTINUE TO REDEVELOP OVER SOUTHEAST MINNESOTA
LATE THIS EVENING IN AN AREA OF WEAK MOISTURE TRANSPORT AND
VERTICAL LIFT AHEAD OF A SHORT WAVE TROUGH COMING ACROSS
MINNESOTA. EXPECT THIS ACTIVITY TO CONTINUE FOR A FEW MORE HOURS
UNTIL THE SHORT WAVE TROUGH MOVES PAST THE AREA AND WILL INITIALLY
HAVE TEMPO GROUPS AND THE VCTS WHEN IT IS SHOULD BE MOVING OUT OF
THE AREA. CONFIDENCE IS HIGHEST THAT KRST WILL CONTINUE TO BE
IMPACTED AS THAT IS WHERE THE NOSE OF THE MOISTURE TRANSPORT IS.
THE RADAR SHOWS THE ACTIVITY WEAKENING AS IT APPROACHES THE
MISSISSIPPI RIVER AND WITH THE MOISTURE TRANSPORT NOT MOVING
MUCH...KLSE MAY NOT SEE A WHOLE LOT OF ACTIVITY SO WILL STAY WITH
VCTS THERE. THE 18.03Z RAP STILL INDICATES THAT LOW STRATUS AND
SOME FOG SHOULD FORM LATE TONIGHT ONCE THE RAIN ENDS...BUT
CONCERNED THAT THE WINDS MAY STAY UP A LITTLE TOO MUCH TO ALLOW
MORE THAN MVFR VISIBILITIES TO DEVELOP. STRATUS EXPECTED TO START
LIFTING LATE MONDAY MORNING WHICH IS WHEN THE NEXT SHORT WAVE
TROUGH WILL BE APPROACHING FROM THE WEST TO START THE NEXT ROUND
OF SHOWERS AND STORMS. FEEL THERE WILL NEED TO BE A PERIOD OF
CATEGORICAL THUNDER FOR BOTH TAF SITES...BUT CONFIDENCE ON WHEN
THIS WILL OCCUR IS TOO LOW TO INCLUDE IT RIGHT NOW. THE 18.00Z NAM
AND 17.12Z HI-RES ARW WOULD SUGGEST LATE AFTERNOON INTO THE
EVENING BUT WHAT IS IN OF THE 18.00Z HI-RES ARW SUGGESTS AS EARLY
AS 18Z MONDAY. WILL CONTINUE WITH VCTS UNTIL THE TRENDS BECOME
CLEARER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1139 PM CDT SUN AUG 17 2014
.SHORT TERM...(TONIGHT THROUGH MONDAY NIGHT)
ISSUED AT 230 PM CDT SUN AUG 17 2014
LATEST WATERVAPOR IMAGERY POINTED TO A SHORTWAVE TROUGH MOVING
SLOWLY EAST ACROSS WESTERN MN...RESPONSIBLE FOR AN AREA OF
SHOWERS/STORMS ACROSS MID/EASTERN SECTIONS OF THE GOPHER STATE.
ANOTHER UPPER LEVEL SHORTWAVE TROUGH WAS SWINGING INTO THE NORTHERN
PLAINS.
THIS FIRST SYSTEM WILL CONTINUE TO MAKE SLOW PROGRESS EAST
TONIGHT...GRADUALLY TRACKING INTO NORTHERN WI. MODELS SUGGEST THAT
THIS FEATURE WILL WEAKEN AND/OR GET PULLED INTO THE NEXT
SHORTWAVE...WHICH WILL TAKE A SPEEDIER PATH ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY ON MONDAY. 25 KT 850 MB JET WILL PROVIDE A
PUSH OF LOW LEVEL MOISTURE FOR THE SYSTEM TO WORK ON MONDAY.
ALTHOUGH WARM CLOUD DEPTHS AREN/T AS DEEP AS RECENT DAYS - ITS STILL
FORECAST TO BE AROUND 3.5 KFT WITH PWS AROUND 1.6. SO...HEAVY RAIN
STILL A GOOD BET WITH ANY OF THE STRONGER STORMS. MUCAPES BUILD IN
EXCESS OF 2000 J/KG BY 00 TUE...WITH THE BULK OF THE SHEAR IN THE 0-
3KM LAYER NEAR 25 KTS. FAIRLY SKINNY CAPE PROFILES ACROSS THE
FORECAST AREA FOR THE MOST PART - PER BUFKIT SOUNDINGS - ALTHOUGH A
BIT MORE FAVORABLE FOR STORM DEVELOPMENT ACROSS NORTHEAST IA.
OVERALL...DON/T SEE AN ORGANIZED SEVERE WEATHER THREAT AT THIS TIME.
BELIEVE HEAVY RAIN AND A CHANCE FOR SMALL HAIL THE MORE LIKELY
OUTCOMES.
ON THE WHOLE...WILL HAVE SOME SCATTERED SHOWERS/STORMS INTO THE
EVENING HOURS FOR SOUTHEAST MN...WITH CHANCES MOSTLY ALONG AND NORTH
OF I-90 THROUGH THE OVERNIGHT. THE GREATER THREAT FOR RAIN WILL COME
LATER IN THE DAY ON MONDAY...AND MOST LOCATIONS CAN EXPECT TO GET
WET.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 230 PM CDT SUN AUG 17 2014
DECENT AGREEMENT IN THE MODELS WITH THE OVERALL PATTERN FOR THE
LATER PART OF THE NEW WEEK. THE GFS/ECMWF POINT TO A FAIRLY
PROGRESSIVE PATTERN WITH SOME MINOR RIDGE BUILDING FRI. BOTH SLIDE
AN UPPER LEVEL SHORTWAVE TROUGH ACROSS THE NORTHERN PLAINS
WED...TRACKING NORTH OF THE REGION ON THU. AN ASSOCIATED SFC WARM
FRONT WILL LIFT ACROSS THE UPPER MISSISSIPPI RIVER VALLEY...WITH
FRONTOGENETIC LIFT AND WARM AIR ADVECTION ALONG IT LIKELY
RESULTING IN A BAND OF SHOWERS/STORMS.
ANOTHER SHORTWAVE TROUGH IS SLATTED TO MOVE OUT OF THE SOUTHERN
ROCKIES AND TAKE AIM ON THE UPPER MISSISSIPPI RIVER VALLEY FRI/SAT.
SOME DISAGREEMENTS BETWEEN THE MODELS ON
TIMING/POSITIONING/STRENGTH...WITH THE GFS THE QUICKER OF THE TWO.
OVERALL...BOTH SOLUTIONS POINT TO ANOTHER ROUND OF SHOWERS/STORMS.
WILL SIDE WITH CONSENSUS FOR RAIN CHANCES FOR NOW.
LOOKING AT A SLOW WARM UP THIS WEEK...WITH SOME MID-UPPER 80 DEGREE
READINGS LIKELY BEFORE THE WORK WEEK IS DONE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1139 PM CDT SUN AUG 17 2014
SHOWERS AND STORMS CONTINUE TO REDEVELOP OVER SOUTHEAST MINNESOTA
LATE THIS EVENING IN AN AREA OF WEAK MOISTURE TRANSPORT AND
VERTICAL LIFT AHEAD OF A SHORT WAVE TROUGH COMING ACROSS
MINNESOTA. EXPECT THIS ACTIVITY TO CONTINUE FOR A FEW MORE HOURS
UNTIL THE SHORT WAVE TROUGH MOVES PAST THE AREA AND WILL INITIALLY
HAVE TEMPO GROUPS AND THE VCTS WHEN IT IS SHOULD BE MOVING OUT OF
THE AREA. CONFIDENCE IS HIGHEST THAT KRST WILL CONTINUE TO BE
IMPACTED AS THAT IS WHERE THE NOSE OF THE MOISTURE TRANSPORT IS.
THE RADAR SHOWS THE ACTIVITY WEAKENING AS IT APPROACHES THE
MISSISSIPPI RIVER AND WITH THE MOISTURE TRANSPORT NOT MOVING
MUCH...KLSE MAY NOT SEE A WHOLE LOT OF ACTIVITY SO WILL STAY WITH
VCTS THERE. THE 18.03Z RAP STILL INDICATES THAT LOW STRATUS AND
SOME FOG SHOULD FORM LATE TONIGHT ONCE THE RAIN ENDS...BUT
CONCERNED THAT THE WINDS MAY STAY UP A LITTLE TOO MUCH TO ALLOW
MORE THAN MVFR VISIBILITIES TO DEVELOP. STRATUS EXPECTED TO START
LIFTING LATE MONDAY MORNING WHICH IS WHEN THE NEXT SHORT WAVE
TROUGH WILL BE APPROACHING FROM THE WEST TO START THE NEXT ROUND
OF SHOWERS AND STORMS. FEEL THERE WILL NEED TO BE A PERIOD OF
CATEGORICAL THUNDER FOR BOTH TAF SITES...BUT CONFIDENCE ON WHEN
THIS WILL OCCUR IS TOO LOW TO INCLUDE IT RIGHT NOW. THE 18.00Z NAM
AND 17.12Z HI-RES ARW WOULD SUGGEST LATE AFTERNOON INTO THE
EVENING BUT WHAT IS IN OF THE 18.00Z HI-RES ARW SUGGESTS AS EARLY
AS 18Z MONDAY. WILL CONTINUE WITH VCTS UNTIL THE TRENDS BECOME
CLEARER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION...04
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
957 PM MDT TUE AUG 19 2014
.UPDATE...
ISSUED AT 958 PM MDT TUE AUG 19 2014
STRONG TO SEVERE THUNDERSTORM CHANCES HAVE ENDED FOR THE REST OF
TONIGHT. WILL MAINLY SEE SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THE REST OF TONIGHT.
&&
.SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)
ISSUED AT 250 PM MDT TUE AUG 19 2014
THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS WHERE THE
CONVECTION WILL BREAK OUT THIS AFTERNOON AND HOW MUCH CONVECTION
WILL BREAK OUT AHEAD OF THE JET STREAK MOVING ACROSS THE ROCKIES
TONIGHT.
LATEST VISIBLE IMAGERY WAS SHOWING SOME ACCAS DEVELOPING ACROSS NORTHEAST
COLORADO NEAR THE SURFACE TROF. THIS AREA MAY END UP BEING THE
FIRST AREA TO FIRE UP THIS AFTERNOON. HOWEVER...IT MAY TRY TO
IGNITE JUST EAST OF THE LARAMIE AND FRONT RANGES AS WELL WHERE WE
HAVE HAD QUITE A BIT OF SUNSHINE. IN FACT...WE ARE STARTING TO SEE
A LITTLE BIT OF ACCAS OVERHEAD AND CONVECTION DEVELOPING ALONG THE
FRONT RANGE. MODELS ARE PROJECTING MIXED LAYER CAPES TO APPROACH 1500
J/KG THIS AFTERNOON WITH VERY LIMITED CAP. 0-6KM SHEAR VALUES
(~30KTS) MAY ALSO BE FAVORABLE FOR A FEW STRONG TO SEVERE STORMS.
AT THIS POINT...IT LOOKS THE HRRR IS STARTING TO BREAK OUT
CONVECTION JUST EAST OF CHEYENNE AFTER 21Z WITH THE BULK OF THIS
CONVECTION PUSHING GENERALLY EAST AT AROUND 20KTS. A FEW OF THESE
STORMS MAY HAVE THE POTENTIAL TO PRODUCING STRONG WINDS AND HAIL IN THE
PANHANDLE THIS AFTERNOON. LATEST SURFACE ANALYSIS WAS ALSO SHOWING
SOME WINDS BACKING TO THE SOUTHEAST IN THE PANHANDLE. WE WILL ALSO
NEED TO WATCH THAT AS THE AFTERNOON WEARS ON...ESPECIALLY IF THE
STORMS GET GOING IN THAT REGION.
ANOTHER CONCERN IS THE NAM IS SHOWING A 500MB JET STREAK MOVING
OUT OF NORTHEAST COLORADO EARLY THIS EVENING WHICH MAY HELP
ENHANCE THE SHEAR ACROSS THE PANHANDLE. IF CONVECTION IS ON GOING
IN THAT REGION AS THIS JET STREAK MOVES ACROSS WE MAY HAVE MORE OF
A SEVERE POTENTIAL. THEREFORE...IT WILL BE A MATTER OF TIMING ON
HOW THINGS COME TOGETHER LATE THIS AFTERNOON AND EVENING.
TONIGHT THE MODELS ARE SHOWING A FAIRLY STRONG UPPER LEVEL JET
MOVING THROUGH NORTHERN COLORADO AND LIFTING NORTHEAST INTO
NORTHEAST WYOMING BY DAYBREAK WHICH WILL HELP ENHANCE UPPER LEVEL
DIFFLUENCE. THE MODELS ARE EVEN IN FAIRLY GOOD AGREEMENT IN
SHOWING A MID LEVEL CIRCULATION WITH THIS JET STREAK. AS A
RESULT... WE WOULD NOT SURPRISED TO SEE A COMPLEX OF SHOWERS AND
THUNDERSTORMS DEVELOP ACROSS THE WESTERN HALF OF THE FORECAST AREA
OVERNIGHT ALONG WITH THE POTENTIAL FOR HEAVY RAINFALL DUE TO PRECIPITABLE
WATER VALUES AROUND 1 INCH. NOT EXPECTING MUCH IN THE WAY OF
FLOODING SINCE THIS COMPLEX SHOULD BE FAIRLY PROGRESSIVE. WE DID
BUMP UP POPS ACROSS THE NORTHERN HALF OF THE AREA TONIGHT TO
REFLECT THIS POTENTIAL.
WEDNESDAY-THURSDAY NIGHT:
THE MID LEVEL CIRCULATION IS PROGGED TO CONTINUE LIFTING NORTHEAST
WHICH WILL TAKE THE BULK OF THE CONVECTION NORTHEAST OF THE
FORECAST AREA BY MID MORNING. THIS WILL LEAVE A FAIRLY BROAD AREA OF
SUBSIDENCE IN THE MORNING IN THE WAKE OF THE CONVECTION...BUT WE
MAY MORE CONVECTION DEVELOP IN THE AFTERNOON ACROSS THE MOUNTAINS
AS UPSLOPE FLOW COMMENCES WITH LEFTOVER RESIDUAL MOISTURE.
OTHERWISE...THE REMAINDER OF THE AREA EAST OF THE LARAMIE RANGE
SHOULD REMAIN FAIRLY DRY WITH HIGHS GENERALLY IN THE 80S. THE
NEXT CHANCE OF SHOWERS AND THUNDERSTORMS IS PROGGED TO TAKE PLACE
ON THURSDAY AFTERNOON AS ANOTHER UPPER LEVEL WAVE LIFTS NORTHEAST
OUT OF COLORADO AND PUSHES THROUGH AREAS EAST OF THE LARAMIE RANGE
THURSDAY AFTERNOON INTO THURSDAY NIGHT.
.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 250 PM MDT TUE AUG 19 2014
AN UPPER LOW AND ASSOCIATED TROUGH OVER THE PACIFIC NW FRIDAY WILL
MOVE SLOWLY EAST TOWARDS THE AREA FRIDAY THROUGH SATURDAY...
SWINGING BY THE AREA ON SUNDAY. THIS WILL COMBINE WITH AT LEAST
RESIDUAL MONSOONAL MOISTURE TO KEEP CHANCES FOR SHOWERS AND TSTMS
GOING OVER MOST AREAS THROUGH SATURDAY NIGHT. WILL CONTINUE TO
LEAN TOWARDS THE EC SOLUTION AS IT HAS BEEN FAIRLY CONSISTENT WITH
THIS FEATURE. WARM TEMPS WILL CONTINUE THROUGH SATURDAY THEN A
DECENT COOL FRONT WILL PASS ACROSS SAT NIGHT LEAVING A DRIER AND
MILD DAY FOR THE CWA SUNDAY. CONTINUED MILD ON MONDAY WITH THE CWA
ON THE SOUTHERN PORTION OF BROAD CYCLONIC UPPER FLOW THAT WILL BE
OVER THE NORTHERN PART OF THE COUNTRY. A SECOND UPPER SHORTWAVE
SHOULD PASS BY TUESDAY BRINGING A REINFORCING SHOT OF COOLER AIR
AND A CHANCE FOR SOME PRECIPITATION.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY AFTERNOON)
ISSUED AT 545 PM MDT TUE AUG 19 2014
ISOLATED TO WIDELY SCATTERED SHOWERS AND TSTMS SHOULD CONTINUE
THROUGH MID TO LATE EVENING ACROSS MUCH OF SOUTHEAST WY AND THE
WESTERN NE PANHANDLE. THE MAIN HAZARD TO AVIATION INTERESTS WILL
BE GUSTY AND ERRATIC SURFACE WINDS WITH GUSTS TO 40 KTS ASSOCIATED
WITH THE STRONGEST STORMS. MVFR VSBYS COULD ALSO OCCUR WITH HEAVY
PRECIPITATION CORES. MENTIONED VCSH OR VCTS IN THE LATEST ISSUANCE
EXCEPT FOR THOSE AREAS SUCH AS AIA THAT ARE MORE LIKELY TO SEE ANY
SIGNIFICANT WEATHER IN THE NEXT FEW HOURS. INCLUDED A TEMPO GROUP
THERE. CIGS SHOULD GENERALLY BE VFR...AT OR AROUND 10K FEET FOR
MOST SITES. SHOWERS WILL INCREASE AGAIN FROM WEST TO EAST FROM
LATE TONIGHT INTO EARLY WED.
&&
.FIRE WEATHER...
ISSUED AT 1056 AM MDT TUE AUG 19 2014
FIRE WEATHER CONCERNS TO REMAIN MINIMAL FOR THE REST OF THE WEEK
WITH NON-CRITICAL WEATHER CONDITIONS EXPECTED. SOME WETTING RAINS
SHOULD OCCUR OVER AT LEAST PARTS OF THE AREA OVER THE NEXT COUPLE
DAYS AS A SURGE OF MONSOONAL MOISTURE PASSES OVER THE REGION AND
INCREASES PRECIPITATION.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
UPDATE...SML
SHORT TERM...REC
LONG TERM...RE
AVIATION...HAMMER
FIRE WEATHER...RE
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
551 PM MDT TUE AUG 19 2014
.SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)
ISSUED AT 250 PM MDT TUE AUG 19 2014
THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS WHERE THE
CONVECTION WILL BREAK OUT THIS AFTERNOON AND HOW MUCH CONVECTION
WILL BREAK OUT AHEAD OF THE JET STREAK MOVING ACROSS THE ROCKIES
TONIGHT.
LATEST VISIBLE IMAGERY WAS SHOWING SOME ACCAS DEVELOPING ACROSS NORTHEAST
COLORADO NEAR THE SURFACE TROF. THIS AREA MAY END UP BEING THE
FIRST AREA TO FIRE UP THIS AFTERNOON. HOWEVER...IT MAY TRY TO
IGNITE JUST EAST OF THE LARAMIE AND FRONT RANGES AS WELL WHERE WE
HAVE HAD QUITE A BIT OF SUNSHINE. IN FACT...WE ARE STARTING TO SEE
A LITTLE BIT OF ACCAS OVERHEAD AND CONVECTION DEVELOPING ALONG THE
FRONT RANGE. MODELS ARE PROJECTING MIXED LAYER CAPES TO APPROACH 1500
J/KG THIS AFTERNOON WITH VERY LIMITED CAP. 0-6KM SHEAR VALUES
(~30KTS) MAY ALSO BE FAVORABLE FOR A FEW STRONG TO SEVERE STORMS.
AT THIS POINT...IT LOOKS THE HRRR IS STARTING TO BREAK OUT
CONVECTION JUST EAST OF CHEYENNE AFTER 21Z WITH THE BULK OF THIS
CONVECTION PUSHING GENERALLY EAST AT AROUND 20KTS. A FEW OF THESE
STORMS MAY HAVE THE POTENTIAL TO PRODUCING STRONG WINDS AND HAIL IN THE
PANHANDLE THIS AFTERNOON. LATEST SURFACE ANALYSIS WAS ALSO SHOWING
SOME WINDS BACKING TO THE SOUTHEAST IN THE PANHANDLE. WE WILL ALSO
NEED TO WATCH THAT AS THE AFTERNOON WEARS ON...ESPECIALLY IF THE
STORMS GET GOING IN THAT REGION.
ANOTHER CONCERN IS THE NAM IS SHOWING A 500MB JET STREAK MOVING
OUT OF NORTHEAST COLORADO EARLY THIS EVENING WHICH MAY HELP
ENHANCE THE SHEAR ACROSS THE PANHANDLE. IF CONVECTION IS ON GOING
IN THAT REGION AS THIS JET STREAK MOVES ACROSS WE MAY HAVE MORE OF
A SEVERE POTENTIAL. THEREFORE...IT WILL BE A MATTER OF TIMING ON
HOW THINGS COME TOGETHER LATE THIS AFTERNOON AND EVENING.
TONIGHT THE MODELS ARE SHOWING A FAIRLY STRONG UPPER LEVEL JET
MOVING THROUGH NORTHERN COLORADO AND LIFTING NORTHEAST INTO
NORTHEAST WYOMING BY DAYBREAK WHICH WILL HELP ENHANCE UPPER LEVEL
DIFFLUENCE. THE MODELS ARE EVEN IN FAIRLY GOOD AGREEMENT IN
SHOWING A MID LEVEL CIRCULATION WITH THIS JET STREAK. AS A
RESULT... WE WOULD NOT SURPRISED TO SEE A COMPLEX OF SHOWERS AND
THUNDERSTORMS DEVELOP ACROSS THE WESTERN HALF OF THE FORECAST AREA
OVERNIGHT ALONG WITH THE POTENTIAL FOR HEAVY RAINFALL DUE TO PRECIPITABLE
WATER VALUES AROUND 1 INCH. NOT EXPECTING MUCH IN THE WAY OF
FLOODING SINCE THIS COMPLEX SHOULD BE FAIRLY PROGRESSIVE. WE DID
BUMP UP POPS ACROSS THE NORTHERN HALF OF THE AREA TONIGHT TO
REFLECT THIS POTENTIAL.
WEDNESDAY-THURSDAY NIGHT:
THE MID LEVEL CIRCULATION IS PROGGED TO CONTINUE LIFTING NORTHEAST
WHICH WILL TAKE THE BULK OF THE CONVECTION NORTHEAST OF THE
FORECAST AREA BY MID MORNING. THIS WILL LEAVE A FAIRLY BROAD AREA OF
SUBSIDENCE IN THE MORNING IN THE WAKE OF THE CONVECTION...BUT WE
MAY MORE CONVECTION DEVELOP IN THE AFTERNOON ACROSS THE MOUNTAINS
AS UPSLOPE FLOW COMMENCES WITH LEFTOVER RESIDUAL MOISTURE.
OTHERWISE...THE REMAINDER OF THE AREA EAST OF THE LARAMIE RANGE
SHOULD REMAIN FAIRLY DRY WITH HIGHS GENERALLY IN THE 80S. THE
NEXT CHANCE OF SHOWERS AND THUNDERSTORMS IS PROGGED TO TAKE PLACE
ON THURSDAY AFTERNOON AS ANOTHER UPPER LEVEL WAVE LIFTS NORTHEAST
OUT OF COLORADO AND PUSHES THROUGH AREAS EAST OF THE LARAMIE RANGE
THURSDAY AFTERNOON INTO THURSDAY NIGHT.
.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 250 PM MDT TUE AUG 19 2014
AN UPPER LOW AND ASSOCIATED TROUGH OVER THE PACIFIC NW FRIDAY WILL
MOVE SLOWLY EAST TOWARDS THE AREA FRIDAY THROUGH SATURDAY...
SWINGING BY THE AREA ON SUNDAY. THIS WILL COMBINE WITH AT LEAST
RESIDUAL MONSOONAL MOISTURE TO KEEP CHANCES FOR SHOWERS AND TSTMS
GOING OVER MOST AREAS THROUGH SATURDAY NIGHT. WILL CONTINUE TO
LEAN TOWARDS THE EC SOLUTION AS IT HAS BEEN FAIRLY CONSISTENT WITH
THIS FEATURE. WARM TEMPS WILL CONTINUE THROUGH SATURDAY THEN A
DECENT COOL FRONT WILL PASS ACROSS SAT NIGHT LEAVING A DRIER AND
MILD DAY FOR THE CWA SUNDAY. CONTINUED MILD ON MONDAY WITH THE CWA
ON THE SOUTHERN PORTION OF BROAD CYCLONIC UPPER FLOW THAT WILL BE
OVER THE NORTHERN PART OF THE COUNTRY. A SECOND UPPER SHORTWAVE
SHOULD PASS BY TUESDAY BRINGING A REINFORCING SHOT OF COOLER AIR
AND A CHANCE FOR SOME PRECIPITATION.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY AFTERNOON)
ISSUED AT 545 PM MDT TUE AUG 19 2014
ISOLATED TO WIDELY SCATTERED SHOWERS AND TSTMS SHOULD CONTINUE
THROUGH MID TO LATE EVENING ACROSS MUCH OF SOUTHEAST WY AND THE
WESTERN NE PANHANDLE. THE MAIN HAZARD TO AVIATION INTERESTS WILL
BE GUSTY AND ERRATIC SURFACE WINDS WITH GUSTS TO 40 KTS ASSOCIATED
WITH THE STRONGEST STORMS. MVFR VSBYS COULD ALSO OCCUR WITH HEAVY
PRECIPITATION CORES. MENTIONED VCSH OR VCTS IN THE LATEST ISSUANCE
EXCEPT FOR THOSE AREAS SUCH AS AIA THAT ARE MORE LIKELY TO SEE ANY
SIGNIFICANT WEATHER IN THE NEXT FEW HOURS. INCLUDED A TEMPO GROUP
THERE. CIGS SHOULD GENERALLY BE VFR...AT OR AROUND 10K FEET FOR
MOST SITES. SHOWERS WILL INCREASE AGAIN FROM WEST TO EAST FROM
LATE TONIGHT INTO EARLY WED.
&&
.FIRE WEATHER...
ISSUED AT 1056 AM MDT TUE AUG 19 2014
FIRE WEATHER CONCERNS TO REMAIN MINIMAL FOR THE REST OF THE WEEK
WITH NON-CRITICAL WEATHER CONDITIONS EXPECTED. SOME WETTING RAINS
SHOULD OCCUR OVER AT LEAST PARTS OF THE AREA OVER THE NEXT COUPLE
DAYS AS A SURGE OF MONSOONAL MOISTURE PASSES OVER THE REGION AND
INCREASES PRECIPITATION.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM...REC
LONG TERM...RE
AVIATION...HAMMER
FIRE WEATHER...RE
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1200 AM MDT MON AUG 18 2014
.UPDATE...
ISSUED AT 905 PM MDT SUN AUG 17 2014
THE EARLIER CRITICAL FIRE WEATHER CONDITIONS HAVE IMPROVED
DRAMATICALLY OVER THE PAST FEW HOURS. SO...IN AN EARLIER
UPDATE LET THE HIGHLIGHT EXPIRE AS SCHEDULED. OTHERWISE...THE
PESKY HIGH-BASED CONVECTION THAT PRODUCED GUSTS OF 55-60 MPH AT A
FEW OBSERVATION SITES EARLIER THIS EVENING...HAVE ALL DISSIPATED
WITH LOSS OF HEATING THIS EVENING. INITIAL LOOKS AT 00Z CONTINUES
TO SUPPORT THE IDEA OF ISOLATED CONVECTION LATE TOMORROW
AFTERNOON...PRIMARILY OVER THE SE WYOMING PLAINS. THE 00Z NAM
TARGETS LARAMIE COUNTY AS HAVING THE BEST CHANCE. WILL SEE WHAT
THE 00Z GFS SUGGESTS BEFORE MAKING ANY CHANGES TO THE FORECAST.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 330 PM MDT SUN AUG 17 2014
AFTERNOON WATER VAPOR LOOP REVEALED A CLOSED UPPER LOW NORTH OF THE
NORTH DAKOTA BORDER WITH A TROUGH AXIS INTO THE WESTERN DAKOTAS.
CLUSTERS OF INTENSE CONVECTION WERE DEVELOPING AHEAD OF THIS FEATURE.
CYS/RIW RADARS SHOWED A FEW SHOWERS DEVELOPING ALONG A WEAK
CONVERGENCE ZONE FROM SOUTHERN NATRONA TO SOUTHERN CONVERSE COUNTY.
THE HRRR MODEL COMPOSITE REFLECTIVITY LOOP SHOWED THIS ACTIVITY
MOVING ACROSS EAST CENTRAL WYOMING THROUGH LATE AFTERNOON THEN
DISSIPATING. WITH VERY DRY SUB-CLOUD LAYER...CAN EXPECT GUSTY WINDS
AND LITTLE IF ANY MEASURABLE RAINFALL WITH THESE SHOWERS. MAIN
CONCERN CONTINUES TO BE FIRE WEATHER IMPACTS FROM THE GUSTY WINDS
AND LOW HUMIDITY FOR ELEVATIONS BELOW 8000 FT. RED FLAG WARNING
REMAINS IN EFFECT FOR ALL BUT THE SIERRA MADRE/SNOWY RANGE ZONES
THROUGH 7 PM. GETTING CLOSE TO RED FLAG CRITERIA OVER THE NEBRASKA
PANHANDLE ZONES BORDERING WYOMING. CONDITIONS WILL IMPROVE THIS
EVENING AS WINDS DECREASE AND HUMIDITIES INCREASE.
A BLEND OF THE 12Z SHORT RANGE MODEL GUIDANCE HANDLES THE LARGE SCALE
PATTERN PRETTY WELL. THE UPPER TROUGH ADVANCES EAST SOUTHEAST ACROSS
THE DAKOTAS AND MIDWEST DURING THE NEXT 24 HOURS. MEANWHILE...A UPPER
RIDGE EXPANDS NORTHWEST FROM THE FOUR CORNERS REGION WITH A HEALTHY
SURGE OF SUBTROPICAL MOISTURE MOVING INTO THE CENTRAL ROCKIES
TUESDAY. PRECIP WATER VALUES MONDAY WILL RANGE FROM A HALF INCH WEST
OF THE LARAMIE RANGE TO AROUND AN INCH FOR THE HIGH PLAINS.
TUESDAY...PRECIP WATER INCREASE TO AROUND 1.25 INCHES EAST OF THE
LARAMIE AND 0.75-1.0 INCH TO THE WEST. DIURNAL CONVECTIVE COVERAGE
MONDAY WILL BE ISOLATED AND CONFINED TO THE MOUNTAINS. THE AIRMASS
OVER THE PLAINS WILL REMAIN CAPPED PRECLUDING SHOWER DEVELOPMENT.
SHOWER/TSTORM COVERAGE INCREASES TO SCATTERED TUESDAY
AFTERNOON/EVENING AS A POTENT SHORTWAVE RIDES NORTHEAST ACROSS
WYOMING AND COLORADO. DOWNSLOPING WESTERLY WINDS WILL LIMIT QPF OVER
THE EASTERN WYOMING PLAINS...WITH AT LEAST O.25 INCH AMOUNTS
POSSIBLE OVER THE HIGHER TERRAIN AND WESTERN NEBRASKA PANHANDLE.
ABOVE NORMAL WARMTH WILL CONTINUE MONDAY LOWER ELEVATIONS MONDAY AND
EAST OF THE LARAMIE RANGE TUESDAY WITH HIGHS IN THE 80S TO LOWER 90S.
TEMPERATURES WILL TREND SLIGHTLY COOLER WEST OF THE LARAMIE RANGE
TUESDAY DUE TO GREATER CLOUD AND SHOWER COVERAGE.
.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 300 PM MDT SUN AUG 17 2014
WARM AND MAINLY DRY WEATHER EXPECTED ACROSS THE CWA WEDNESDAY AND
THURSDAY THOUGH A FEW SHOWERS/TSTRMS POSSIBLE OVER THE HIGHER SRN
MTNS BOTH AFTERNOONS/EARLY EVENINGS. CHANGES LOOK TO BE IN THE
OFFING BEGINNING FRIDAY AND CONTINUING INTO THE WEEKEND AS AN
UPPER TROF SETTLES OVER THE NW PART OF THE COUNTRY AND A PUSH OF
COOLER CANADIAN AIR DROPS DOWN THE HIGH PLAINS SATURDAY AND
SATURDAY NIGHT WITH THE EC CONTINUING TO BE MUCH MORE BULLISH IN
PUSHING THIS COOL AIR ACROSS THE CWA BY LATE SATURDAY...SETTING UP
A MILD DAY FOR SUNDAY. EC HAS BEEN CONSISTENT WITH THIS. SHOULD
ALSO SEE A BIT OF AN UPTICK IN CONVECTION FRIDAY AND SATURDAY AS
THE UPPER TROF NEARS WITH ANY ASSOCIATED IMPULSES ROUNDING THE
BASE OF IT PASSING ACROSS THE AREA.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY EVENING)
ISSUED AT 1159 PM MDT SUN AUG 17 2014
A WEAK COLD FRONT HAS MOVED THROUGH THE MAJORITY OF THE CWA THIS
EVENING...WITH WINDS BEHIND THE FRONT OUT OF THE EAST-NORTHEAST
AND REMAINING LIGHT. WINDS WILL CONTINUE TO BE LIGHT ON MONDAY
WITH THE UPSLOPE COMPONENT HELPING TO SPARK OFF SHOWERS AND
TSTORMS IN THE AFTERNOON. HIGHEST CHANCE FOR STORMS WILL BE NEAR
KCYS AND KLAR AFTER 19Z.
&&
.FIRE WEATHER...
ISSUED AT 703 PM MDT SUN AUG 17 2014
CONDITIONS WILL CONTINUE TO IMPROVE ACROSS THE DISTRICTS THROUGH
THE REST OF THE EVENING. THEREFORE...ALLOWED THE RED FLAG WARNING
TO EXPIRE AT 7 PM.
FIRE WEATHER CONCERNS WILL BECOME MINIMAL MONDAY AND TUESDAY AS AN
INFLUX OF MONSOON MOISTURE FROM THE SOUTHWEST INCREASES CHANCES
FOR WETTING RAINS EARLY THIS WEEK. WINDS WILL BE LIGHTER AS WELL.
DRIER CONDITIONS RETURN MID WEEK FOLLOWED BY A SLIGHT INCREASE IN
MOISTURE LATE IN THE WEEK. ABOVE AVERAGE TEMPERATURES THIS WEEK
WILL GRADUALLY COOL NEXT WEEKEND.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
UPDATE...HAHN
SHORT TERM...JAMSKI
LONG TERM...RE
AVIATION...RJM
FIRE WEATHER...JAMSKI
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
1015 PM PDT TUE AUG 19 2014
...UPDATED AVIATION DISCUSSION...
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE REGION AND INCREASE
THE NIGHT THROUGH MORNING CLOUDS AND FOG THROUGH SATURDAY. THE
MOIST AIR MASS WILL BRING LOCAL DRIZZLE...AND A SLIGHT CHANCE OF
SHOWERS OR THUNDERSTORMS TO THE SOUTHLAND THROUGH THURSDAY. A
HIGH PRESSURE SYSTEM WILL LIKELY ESTABLISH FOR EARLY NEXT WEEK
WITH ABOVE NORMAL TEMPERATURES.
&&
.UPDATE...
THE WATER VAPOR IMAGERY INDICATES A LOW PRESSURE SYSTEM
CONTINUING TO DIG SOUTH OFF THE SOUTHERN CALIFORNIA COAST THIS
EVENING. SOME CONVECTION HAS FIRED OFF TO THE SOUTH AND EAST OF
THE AREA...BUT THE AREA HAS REMAINED DRY. A DEEP MARINE LAYER
SHOULD BRING AN EXTENSIVE MARINE LAYER INDUCED STRATUS FIELD TO
THE MUCH OF THE COASTAL AND VALLEY AREAS LATER TONIGHT. THE LATEST
FOG PRODUCT IS GIVING INDICATIONS OF A RAPID FILLING-IN OF
STRATUS LATE THIS EVENING. DRIZZLE OR LIGHT SHOWERS FROM THE
STRATUS DECK CANNOT BE RULED AS THE INSTABILITY OF THE TROUGH
APPROACHES AND RAPID DEEPENING OF THE MARINE LAYER TAKES PLACE.
THE LATEST NAM-WRF AND RAP SOLUTIONS SUGGEST THE TIMING OF THE
CONVECTION OCCURRING A LITTLE EARLIER THAN PREVIOUSLY THOUGHT.
BOTH 00Z NAM-WRF SOLUTIONS AND THE LATEST RAP SOLUTIONS SUGGEST AN
AREA OF NEGATIVE LIFTED INDEX VALUES FORMING OVER THE SOUTHERN
COASTAL WATERS LATE TONIGHT WHEN THE COLDEST AIR ALOFT WITH THE
TROUGH MOVES INTO THE REGION. AN AREA OF DIFLUENCE FLOW ALOFT
SHOULD DEVELOP AHEAD OF THE MAIN VORTICITY MAXIMUM AND SHOULD
ALLOW FOR SHOWERS AND THUNDERSTORMS TO FIRE...EVEN ABOVE THE
MARINE LAYER STRATUS DECK. POPS HAVE BEEN BUMPED FOR THE COASTAL
WATERS AND THE LOS ANGELES COUNTY COAST AFTER MIDNIGHT TONIGHT.
THE LATEST NAM-WRF SOLUTIONS CONTINUE TO SLOW THE TROUGH...BEING
LESS PROGRESSIVE RELATIVE TO THE GFS AND ECMWF SOLUTIONS. IF NAM-
WRF SOLUTIONS PLAY OUT...POPS AND WEATHER MAY NEED TO BE ADDED FOR
THURSDAY AS THE TROUGH AXIS LINGERS OVER THE AREA. WHILE THE NAM-
WRF SOLUTIONS REMAIN THE OUTLIER...THE TROUGH IS CUT-OFF FROM THE
FLOW AND TYPICALLY MODEL PERFORMANCE WITH CLOSED AND CUT-OFF LOWS
WOULD FAVOR NAM-WRF SOLUTIONS FOR SOUTHERN CALIFORNIA AND
SOUTHWESTERN UNITED STATES. WITH THE NWS WEATHER PREDICTION CENTER
MENTIONING SREF SOLUTIONS FAVORING RETROGRESSION OF THE
TROUGH...IT IS POSSIBLE THAT THE NAM-WRF SOLUTION MAY NOT BE TOO
FAR OFF. THE NEXT SHIFT WILL BE BRIEFED ABOUT POPS AND WEATHER
POSSIBILITIES FOR THURSDAY.
&&
.PREV DISCUSSION...
SHORT TERM...THE UPPER LOW MOVES SOUTHEAST TO THE HIGH DESERTS
ON THURSDAY. THE LAST BIT OF INSTABILITY AND MOISTURE WILL BE OVER
THE EASTERN SAN GABRIEL MOUNTAINS FOR A CONTINUED SLIGHT CHANCE OF
THUNDERSTORMS. A SHALLOWER MARINE LAYER IS LIKELY ON THURSDAY
MORNING BUT WILL STILL SEE LOW CLOUDS FOR COASTS AND NEARBY
VALLEYS TO START THE DAY. BY FRIDAY MORNING THE MARINE LAYER
SHRINKS EVEN MORE AND MAY ONLY SEE PATCHY CLOUDS SOUTH OF PT
CONCEPTION. TEMPERATURES WILL START TO REBOUND LATE IN THE WEEK
BUT A LARGE SCALE UPPER TROUGH ACROSS MOST OF THE WEST WILL SLOW
ANY SIGNIFICANT WARMING UNTIL LATER IN THE WEEKEND.
LONG TERM...HIGH PRESSURE SLOWLY BUILDS ACROSS THE SOUTHWEST OVER
THE WEEKEND WITH TEMPERATURES WARMING AND THE MARINE LAYER
BECOMING LESS OF AN ISSUE FOR COASTAL AREAS. VERY LITTLE
SIGNIFICANT WEATHER ISSUES THROUGH TUESDAY. REMNANT MOISTURE FROM
TWO TROPICAL SYSTEMS (LOWELL AND KARINA) COULD GET PULLED
NORTHWARD CLOSER TO SOUTHERN CALI BY MONDAY OR TUESDAY. WOULD ONLY
EXPECT SOME MID TO HIGH LEVEL CLOUDS FROM THESE SYSTEMS AT BEST
WITH LITTLE EFFECT ON TEMPERATURES.
&&
.AVIATION...20/0515Z...
OVERALL...MODERATE CONFIDENCE IN 06Z TAF PACKAGE. WITH UPPER LOW
WOBBLING NEAR THE AREA...MARINE INVERSION SHOULD DEEPEN AND MVFR
CIGS SHOULD IMPACT ALL COASTAL/VALLEY TAF SITES OVERNIGHT. COULD BE
SLOW TO CLEAR WEDNESDAY AFTERNOON SOUTH OF POINT CONCEPTION...BUT
THE PREVIOUSLY MENTIONED UPPER LOW COULD MIX OUT THE MVFR CIGS
EARLIER/BETTER THAN ANTICIPATED. WITH THE DEEPENING INVERSION...THERE
COULD BE SOME PATCHY DRIZZLE WEST OF THE MOUNTAINS OVERNIGHT.
OTHER ISSUE TO WATCH WILL BE SLIGHT CHANCE OF TSTMS IMPACTING MAINLY
LOS ANGELES COUNTY LATE TONIGHT AND WEDNESDAY. AT THIS TIME...WILL
MENTION A VCTS REMARK WEDNESDAY AFTERNOON FOR KPMD/KWJF. HOWEVER
DEPENDING ON HOW THINGS DEVELOP LATE TONIGHT...THERE IS THE
POTENTIAL FOR TSTMS TO IMPACT KLAX/KLGB/KBUR/KVNY. WILL WATCH THE
SITUATION CLOSELY.
KLAX...MODERATE CONFIDENCE IN 06Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH WEDNESDAY MORNING...WITH LOW CONFIDENCE IN CLEARING
WEDNESDAY AFTERNOON. THERE IS A 10% CHANCE OF TSTMS IMPACTING THE
AIRFIELD LATE TONIGHT/WEDNESDAY.
KBUR...MODERATE CONFIDENCE IN 06Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH WEDNESDAY MORNING. LOW CONFIDENCE IN CURRENT FORECAST/TIMING
OF CLEARING WEDNESDAY AFTERNOON. THERE IS A 10% CHANCE OF TSTMS
IMPACTING THE AIRFIELD LATE TONIGHT/WEDNESDAY.
&&
.MARINE...19/900 PM.
TIMING FOR CHANCES FOR SHOWERS AND THUNDERSTORMS HAS BEEN BUMPED
TO AN EARLIER TIME FRAME. SHOWERS AND THUNDERSTORMS COULD DEVELOP
ACROSS THE SOUTHERN WATERS AFTER MIDNIGHT TONIGHT. GUSTY AND
ERRATIC WINDS...CHOPPY SEAS...SMALL HAIL...AND DANGEROUS CLOUD-TO-
OCEAN LIGHTNING ARE POSSIBLE AFTER MIDNIGHT TONIGHT AND THROUGH
WEDNESDAY MORNING. OTHERWISE...WINDS AND SEAS WILL REMAIN BELOW
SMALL CRAFT ADVISORY LEVELS.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWWLOX).
&&
$$
PUBLIC...HALL/BOLDT
AVIATION...GOMBERG
MARINE...HALL
SYNOPSIS...SETO/HALL
WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1121 PM MDT TUE AUG 19 2014
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 249 PM MDT TUE AUG 19 2014
WV SATELLITE IMAGERY TODAY SHOWING THE MONSOON MSTR PLUME OVR
UT...BUT SLOWLY SHIFTING EASTWARD AS AN UPR LOW MOVES SOUTHWARD
ALONG THE CA COAST. SCATTERED SHOWERS AND TSTMS ARE EXPECTED THIS
EVENING OVR THE MTNS AND UPR ARKANSAS RIVER VALLEYS...WITH ISOLD
ACTIVITY OVR THE SERN PLAINS. BY 03Z THE HRRR AND RAP SHOW LITTLE IF
ANY PCPN OVR THE SERN PLAINS...WITH JUST SOME ISOLD PCPN OVR THE MTN
AREAS. OVERNIGHT THAT UPR LOW WL MOVE OVR SRN CA AND THE MONSOON
PLUME SHIFTS INTO WRN CO. AS A WX DISTURBANCE THE MSTR LIFTS
NORTHEASTWARD ACRS NWRN CO...SOME PCPN WL PROBABLY CONTINUE THRU THE
NIGHT ALONG THE CONTDVD...ESPECIALLY OVR THE CENTRAL CO MTNS WHICH
WL BE CLOSEST TO THE DISTURBANCE AND BETTER MSTR.
ON WED THE UPR LOW IS EXPECTED TO REMAIN OVR SRN CA. THE BEST MSTR
GOES NORTH OF THE AREA WITH THAT DISTURBANCE...AND MODELS ARE MAINLY
SHOWING SPOTTY PCPN FOR THE FORECAST AREA. WILL KEEP SCT POPS OVR
THE MTNS AREAS FOR WED AFTERNOON AND ISOLD POPS OVR THE SAN LUIS
VALLEY AND I-25 CORRIDOR. HIGH TEMPS ON WED SHOULD GENERALLY BE
AROUND TO A LITTLE ABOVE AVERAGE.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 249 PM MDT TUE AUG 19 2014
THE UPPER LEVEL PATTERN IS FORECAST TO FEATURE A BROAD UPPER LEVEL
TROUGH OVER THE NORTHWEST TO NORTH-CENTRAL CONUS AND A HIGH
PRESSURE CENTER OVER THE SOUTHEAST STATES. THIS WILL PUT SOUTHERN
COLORADO UNDER SOUTHWESTERLY FLOW FOR MUCH OF THE EXTENDED. THERE
ARE MODEL DIFFERENCES IN HOW THEY WANT TO HANDLE UPPER LEVEL
DISTURBANCES IN THE FLOW...AND ENSEMBLES DEVELOP HIGH SPREADS BY
THIS WEEKEND LEADING TO LOWER CONFIDENCE IN THE LAST COUPLE OF
DAYS OF THE EXTENDED PERIOD.
THE GFS HAS REMAINED CONSISTENT FROM RUN TO RUN WITH AN UPPER
LEVEL LOW OVER SOUTHERN CALIFORNIA AND EJECTING IT NORTHEAST
ACROSS COLORADO ON THURSDAY NIGHT INTO FRIDAY. THE LATEST ECMWF IS
MORE IN LINE WITH THIS SOLUTION...HOWEVER IS ABOUT 24 HOURS SLOWER
IN EJECTING THE SYSTEM OUT. THE BIGGEST FORECAST CHANGE FOR THE
GFS IS WHERE THE SYSTEM DEVELOPS CONVECTION ON THURSDAY.
EXPECT ONGOING CONVECTION ACROSS THE MOUNTAINS WEDNESDAY EVENING
WITH MODELS BRINGING BAND EAST ACROSS THE PLAINS THROUGH THE
OVERNIGHT HOURS AS A WEAK DISTURBANCE LIFTS NORTHEAST. BY THURSDAY
MORNING...THE LOW PRESSURE CENTER OVER SOUTHERN CALIFORNIA IS
FORECAST TO OPEN UP AND LIFT NORTHEAST ACROSS COLORADO.
THUNDERSTORMS ARE FORECAST TO DEVELOP OVER THE MOUNTAINS BY LATE
THURSDAY MORNING. THUNDERSTORMS DEVELOPMENT IS THEN EXPECTED
EASTWARD ACROSS THE PALMER DIVIDE THROUGH THE AFTERNOON AND
EVENING HOURS. THE PREVIOUS RUN OF THE GFS HAD THIS THUNDERSTORM
DEVELOPMENT FURTHER SOUTH OVER SOUTHERN COLORADO...SO WHERE THIS
DISTURBANCE EJECTS WILL PLAY A ROLE IN WHAT AREAS SEEN THE
POTENTIAL FOR HEAVIER PRECIPITATION. THE ECMWF AND NAM SOLUTIONS
ARE A BIT SLOWER WITH THIS SYSTEM...WITH IT EJECTING ACROSS
SOUTHERN COLORADO ON FRIDAY AFTERNOON. IF THIS IS THE
CASE...THURSDAYS CONVECTION WILL LIKELY REMAIN TIED TO THE TERRAIN
AND PALMER DIVIDE...WITH NOT MUCH EXPECTED ON THE PLAINS. THE
HEAVY PRECIPITATION CHANCES WOULD THEN FOCUS ON FRIDAY AFTERNOON
AND NIGHT...WITH HEAVY RAINFALL AND THE POTENTIAL FOR FLASH
FLOODING. THE IMPORTANT THING TO REMEMBER...IS THAT SOME TIME
BETWEEN THURSDAY AND FRIDAY NIGHT...SOUTHERN COLORADO WILL LIKELY
SEE A PERIOD OF WIDESPREAD HEAVIER RAINFALL.
A BROAD TOUGH IS FORECAST TO REMAIN ENTRENCHED ACROSS THE PACIFIC
NORTHWEST INTO THE NORTHERN PLAINS SATURDAY THROUGH TUESDAY. THE
MAIN FORECAST ISSUE WILL BE HOW DEEP THE TROUGH GETS. THE GFS
SOLUTIONS DIGS IT THE FURTHEST SOUTH...WITH CONTINUED ACTIVE
WEATHER ACROSS THE AREA...WHILE THE ECMWF IS KEEP MOST OF THE
ENERGY CONFINED TO OUR NORTH WITH LESS CHANCES FOR PRECIPITATION.
A COLD FRONT IS FORECAST TO DROP SOUTH ACROSS THE PLAINS ON SUNDAY
WHICH MAY BE THE BEST OPPORTUNITY FOR WIDESPREAD PRECIPITATION
ACROSS THE AREA. OTHERWISE...CONVECTION WILL LIKELY REMAIN OVER
THE MOUNTAINS WITH LIMITED ACTIVITY OVER THE PLAINS. MOZLEY
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1121 PM MDT TUE AUG 19 2014
MAINLY VFR CONDITIONS EXPECTED AT COS...PUB AND ALS OVER THE NEXT
24 HOURS...WITH ISOLATED TO SCATTERED AFTERNOON AND EVENING SHOWERS
AND THUNDERSTORMS REMAINING IN THE FORECAST. BEST COVERAGE OF STORMS
TO REMAIN OVER AND NEAR THE HIGHER TERRAIN AND WILL KEEP VCTS AFT
20Z IN TAFS AT THIS TIME. GUSTY WINDS TO 45 MPH AND BRIEF MODERATE
TO HEAVY RAINFALL WILL BE POSSIBLE WITH STORMS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...28
LONG TERM...MOZLEY
AVIATION...MW
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1034 PM MDT TUE AUG 19 2014
.UPDATE...
ISSUED AT 947 PM MDT TUE AUG 19 2014
MAINLY STRATIFORM PRECIPITATION CONTINUES THIS EVENING WITH A FEW
RUMBLES OF THUNDER THANKS TO EMBEDDED CONVECTION. LATEST NAM12 RUN
NOT INTIALIZING WELL...NOR IS THE GFS WITH BOTH SHOWING WIDESPREAD
AND HEAVY PRECIP OVERNIGHT WHILE HRRR IS CAPTURING PRECIP IN OUR
AREA PRETTY WELL. HRRR ALSO SHOWS SOME SHOWERY ACTIVITY
CONTINUING OVERNIGHT BUT COVERAGE IS ISOLATED AT BEST. LOOKING
UPSTREAM...RADAR MOSAIC SHOWING CONVECTION OVER EXTREME WRN UT/ERN
NV WITH NOT MUCH IN BETWEEN. IR IMAGERY IS ALSO SHOWING WARMING
CLOUD TOPS ACROSS OUR CWA INDICATING STRONGEST CONVECTION HAVING
ENDED. DO HAVE SOME CONCERN THAT UPPER LEVEL JET MOVING OVERHEAD
MAY FIRE OFF MORE CONVECTION OVERNIGHT BUT WITH DIVERGENCE
WEAKENING...WILL GO WITH MORE SCT TO ISOLD COVERAGE.
&&
.SHORT TERM...(TONIGHT THROUGH WEDNESDAY NIGHT)
ISSUED AT 344 PM MDT TUE AUG 19 2014
CURRENT IR SATELLITE SHOWS TWO PRECIPITATION HOT SPOTS - ONE WEST
OF VERNAL AND THE OTHER DOWN BY THE FOUR CORNERS. RADAR RETURNS
SHOW THE OUTER PERIPHERY OF THE ENHANCEMENT AT BLANDING UTAH AT
315PM. THIS RAIN WILL EXPAND TO THE NORTHEAST THROUGH THE LATE
AFTERNOON AND EVENING AS PRECIPITABLE WATER VALUES REACH THEIR
MAXIMUM OF ONE INCH TO 1.2 INCHES ACROSS THE REGION. A SERIES OF
H5 VORT MAXES ALONG WITH AN APPROACHING H3 50KT JET WILL MOVE
INTO THE AREA THIS EVENING...HELPING TO SUSTAIN SHOWERS AND
OCCASIONAL EMBEDDED THUNDERSTORMS. STORM MOTION STILL LOOKS TO BE
20 TO 30 KTS WITH MINIMAL TRAINING OCCURRING SO FAR.
SOME SUBSIDENCE OVER THE REGION TOMORROW WILL HINDER HIGH
LIKELIHOOD OF SHOWERS AND THUNDERSTORMS...HOWEVER FORECAST CIN IS
LOW OR NONEXISTENT BY THE AFTERNOON...AND AMPLE MOISTURE AND
BREAKS IN THE CLOUDS WILL BE IN PLACE TO INITIATE
ISOLATED/SCATTERED CONVECTION IN THE AFTERNOON. STEERING FLOW WILL
SLOW BY MIDDAY TO 10 TO 15 KTS. EXPECTING ACTIVITY TO OCCUR
EARLIER IN THE AFTERNOON AND TAPER OFF FOR THE MOST PART IN THE
EVENING.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 344 PM MDT TUE AUG 19 2014
WEATHER THE LAST HALF OF THE WEEK DEPENDS LARGELY ON THE UPPER LOW
CURRENTLY DROPPING SOUTH ALONG THE CA COAST. MODELS CONTINUE TO
HAVE SOME DIFFICULTY HANDLING THIS LOW. THE GFS REMAINS THE MOST
PROGRESSIVE...SWINGING IT IN INLAND ACROSS SRN CA THU AND UP
THROUGH ERN UT/WRN CO THU NIGHT. THE NAM AND ECMWF ARE SLOWER BY
ABOUT 12-24 HRS ON A TRACK A LITTLE FARTHER SOUTH. NUDGED POPS
UPWARD THU-FRI BUT REMAINED CONSERVATIVE DUE TO THE TIMING
DIFFERENCES.
SOME STORMS COULD BE RATHER STRONG THU-FRI GIVEN THAT THE DEEP LAYER
Q-G FORCING MAXIMA MOVES ACROSS THE AREA...AND 0-6KM VERTICAL WIND
SHEAR INCREASES WITH TROUGH PASSAGE...REGARDLESS OF MODEL. MODELS
ALSO HINT AT BRIEF ENTRAINMENT OF SOME MOISTURE FROM TROPICAL
STORM LOWELL...REFLECTED MORE IN THE 320K/325K ISENTROPIC SURFACE
HUMIDITY THAN PRECIPITABLE WATER FORECAST.
CONCURRENTLY...SHORTWAVE ENERGY SHARPENS AN UPPER TROUGH OVER THE
PAC NW AND NRN ROCKIES LATE IN THE WEEK. THIS TROUGH THEN SLOWLY
MIGRATES EASTWARD TO THE NORTHERN PLAINS AND SOUTHERN CANADA BY
MONDAY AFTERNOON. THIS SHOULD RESULT IN SOMEWHAT DRIER WESTERLY FLOW
ACROSS OUR AREA BY SUNDAY FOR A DOWNTURN IN SHOWER AND STORM
ACTIVITY THIS WEEKEND THROUGH EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 947 PM MDT TUE AUG 19 2014
-RA BEING REPORTED ALONG AND N OF I-70 THIS EVENING WITH KRIL
COMING IN WITH SOME MVFR CIGS WHILE REMAINING TAF SITES REPORTING
CIGS AROUND 6 TO 7K. AS THIS PRECIP CONTINUES SHIFTING TO THE NE...VFR
CONDITIONS ARE EXPECTED WITH BKN TO OVC SKIES. LATEST GUIDANCE
SHOWING MORE OF A DOWN DAY TOMORROW WITH SOME ISOLD CONVECTION TO
CONTEND WITH ACROSS THE CWA WITH MTN TAF SITES AND POSSIBLY SOME
VALLEY SITES SEEING SOME -RA...VCTS...OR A PASSING -TSRA.
&&
.HYDROLOGY...
ISSUED AT 344 PM MDT TUE AUG 19 2014
MONSOONAL MOISTURE IS RETURNING THIS EVENING AS AN UPPER LEVEL
LOW OVER CALIFORNIA PULLS DEEP SUBTROPICAL MOISTURE INTO THE
REGION. SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE FROM
WEST TO EAST THIS EVENING...PEAKING THIS EVENING THEN CONTINUING
OVERNIGHT INTO WEDNESDAY MORNING. EXPECT SOME SMALL STREAM AND
ARROYO FLOOD ISSUES BY WEDNESDAY MORNING IN THE USUAL PROBLEM
AREAS. HOWEVER...DO NOT EXPECT SUFFICIENTLY WIDESPREAD COVERAGE OF
TORRENTIAL DOWNPOURS TO WARRANT FLASH FLOOD WATCH.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
UPDATE...TGR
SHORT TERM...JAM
LONG TERM...JAD
AVIATION...TGR
HYDROLOGY...NL/JAM
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
406 AM CDT WED AUG 20 2014
.DISCUSSION...
320 AM CDT
SHORT TERM...THROUGH WEDNESDAY NIGHT...
FOR THE REMAINDER OF THE OVERNIGHT HOURS...CONDITIONS WILL REMAIN
QUIET WITH HIGH PRESSURE OVERHEAD AND THE PESKY UPPER LOW LIFTING
INTO THE UPPER GREAT LAKES AND ANY ASSOCIATED CONVECTION MOVING WELL
TO THE EAST. UNDER CLEAR SKIES AND LIGHT WINDS...EXPECT THAT SOME
LOCATIONS COULD SEE SOME FOG DEVELOPMENT...MAINLY LOW LYING AND
SHELTERED AREAS. DO NOT EXPECT WIDESPREAD DENSE FOG AS DEWPOINT
DEPRESSIONS ARE STILL 3-5 DEGREES IN MANY PLACES. CONDITIONS WILL
REMAIN QUIET INTO WEDNESDAY BUT UPPER RIDGING BUILDING OVER THE
CENTRAL PLAINS AND ACROSS THE MIDDLE AND UPPER MISSISSIPPI VALLEY
WHILE THE UPPER LOW CONTINUES TO LIFT TO THE NORTHEAST IS SIGNALING
THE BEGINNING OF A SIGNIFICANT WARMING TREND...MORE LIKE THE TRUE
DOG DAYS OF SUMMER THAT THE UNSEASONABLY COOL WEATHER THAT THE AREA
HAS SEE FOR MUCH OF THIS SUMMER. ACCOMPANYING THE UPPER RIDGING AND
INCREASING TEMPERATURES ALOFT WILL BE AN INCREASE OF LOW LEVEL
MOISTURE. THE BERMUDA HIGH IS IN PLACE OVER THE ERN GLFMEX WHILE
A TROUGH OF LOW PRESSURE IS DEVELOPING OVER THE CENTRAL PLAINS.
THIS IS SETTING UP A RETURN FLOW OF MOISTURE FROM A WIDE OPEN GULF
OF MEXICO...WITH 20-30KT 850MB WINDS WITH TRAJECTORIES OFF OF THE
WESTERN GLFMEX POINTING RIGHT INTO THE MIDWEST. UNDER AMPLE SUNSHINE
FOR MOST OF THE DAY TODAY...THERE SHOULD BE LITTLE TROUBLE MIXING
DOWN THE WARMER AIR ALOFT...WHERE 850MB TEMPS SHOULD BE ARND
18-20C. SO...THE AREA WILL SEE HIGHS TODAY IN THE MIDDLE TO UPPER
80S. WITH DEWPOINTS IN THE MIDDLE TO UPPER 60S...THE MAX HEAT INDEX
TODAY SHOULD BE IN THE UPPER 80S TO LOWER 90S. WHILE THESE HEAT
INDEX VALUES ARE NOT ANYWHERE NEAR HEADLINE LEVELS...THEY ARE
CERTAINLY MUCH HIGHER THAN HAS BEEN SEEN FOR THE BULK OF THE
SUMMER.
SHOWERS AND THUNDERSTORMS WILL BECOME AN INCREASING CONCERN THROUGH
THE AFTERNOON AND INTO WEDNESDAY NIGHT. EARLY THIS MORNING...THERE
IS ONGOING CONVECTION OVER THE UPPER MISSOURI VALLEY ASSOCIATED WITH
A SHORTWAVE OVER TOPPING THE UPPER RIDGE. EXPECT THAT THIS ACTIVITY
SHOULD SLIDE SOUTHEAST OF THE CWA THIS MORNING...MOVING THROUGH SRN
IA/NRN MO AND INTO CNTRL/SRN IL. THE MODELS ARE CONSISTENT IN
DEVELOPING A WARM FRONT EXTENDING EAST FROM A DEEPENING LOW OVER THE
DAKOTAS THROUGH THE MIDDLE MISSISSIPPI VALLEY BY EARLY WEDNESDAY
EVENING. THIS SHOULD BE THE FOCUS FOR SHRA/TSRA SPREADING INTO THE
REGION FROM SOUTHWEST TO NORTHEAST THROUGH THE EVENING AND OVERNIGHT
HOURS WEDNESDAY NIGHT. HAVE MAINTAINED A MORE BROADBRUSHED
APPEARANCE TO THE WX/POP/QPF GRIDS FOR WEDNESDAY NIGHT DUE TO SOME
CONCERN WITH TIMING OF THE PCPN SPREADING NWD AS THERE IS STILL SOME
UNCERTAINTY IN THE MODELS AS FAR AS TIMING THE LEADING EDGE OF THE
PCPN...BUT HAVE GONE WITH LIKELY POPS AS CONFIDENCE IS HIGHER IN THE
POTENTIAL FOR PCPN. CONFIDENCE IS JUST A LITTLE LOWER IN THE ONSET
TIME. WHILE THE SEVERE POTENTIAL WILL BE LOW...A GREATER CONCERN
WILL BE LOCALLY HEAVY RAINFALL. AS SWLY FLOW AND WARM/MOIST
ADVECTION INCREASES THROUGH WEDNESDAY NIGHT...THE MODEL GUIDANCE IS
INDICATING PWATS AROUND 2 INCHES OVER THE AREA. WITH UPPER LEVEL
WINDS FROM JUST ABOVE THE SURFACE THROUGH THE COLUMN EXPECTED TO BE
ARND 25-30KT...THE THUNDERSTORM ACTIVITY SHOULD BE PROGRESSIVE.
SO...WHILE LOCALLY HEAVY RAINFALL IS QUITE POSSIBLE...WIDESPREAD
FLOODING IS NOT ANTICIPATED THOUGH LOCALIZED URBAN AND SMALL STREAM
ADVISORY TYPE FLOODING REMAINS A POSSIBILITY.
KREIN
THURSDAY THROUGH SUNDAY...
MAIN CONCERN IN THE MEDIUM TERM WILL RESIDE ON THE
PLACEMENT/STRENGTH OF THE 500MB RIDGE POISED TO SETUP ACROSS THE
OZARKS. GUIDANCE HAS BEEN CONSISTENTLY SUGGESTING AN ATMOSPHERIC
RIVER DEVELOPING ACROSS THE NORTHERN PLAINS AND BECOMING ORIENTED
ALONG THE NORTHERN PERIPHERY OF THE MID-LVL RIDGE...THEN TURNING
SOUTHEAST ACROSS THE ALLEGHENIES IN PENNSYLVANIA. CONCERN DOES ARISE
WITH THE FACT THAT MEDIUM RANGE GUIDANCE HAS DEMONSTRATED A REDUCED
LEVEL OF CONFIDENCE WITH SPREAD IN HOW AMPLIFIED THE RIDGE WILL
BECOME...WHICH COULD BE STARTING TO HINT THAT THE ACTIVE RING-O-FIRE
MAY END UP CLOSER TO THE FORECAST AREA THUR NGT/FRI. AT THIS TIME
HAVE ONLY MADE MINOR ADJUSTMENTS WITH THE POPS...AND EXPECT A
CHANNEL OF LIKELY POPS TO BE LIFTING NORTH THUR MIDDAY INTO WISC BY
THUR NGT. CURRENT OPER SOLUTIONS STILL FAVOR THIS SCENARIO...PLUS
850MB TEMPS WILL BE STEADILY WARMING AND SHUD LIMIT THE COVERAGE OF
CONVECTION/PRECIP.
THEN INTO FRI SOLUTIONS SUGGEST THE TOP OF THE RIDGE MAY BEGIN TO
FLATTEN. LOCAL ARW8KM ALSO HINTS THAT THE ACTIVE ZONE MAY BE
DRIFTING SOUTH AND COULD BE OVER THE FORECAST AREA FRI AFTN/EVE.
THEN FOR SAT RIDGE REMAINS OVERHEAD...BUT IT STILL LOOKS POSSIBLE
FOR CHC POPS TO START THE WEEKEND. THE ONE CONSISTENCY THROUGH THE
THUR-SAT TIMEFRAME...THE HEAT/HUMIDITY. WHILE PWAT VALUES CONTINUE
TO HOVER IN THE 1.6-1.8" RANGE...THE FORECAST DEW PTS ARE EXPECTED
TO LINGER IN THE LOW TO PERHAPS MID 70S FOR MANY LOCATIONS THUR-SAT.
SFC TEMPS ARE PROGGED TO PUSH WELL INTO THE 80S...AND PERHAPS WARMER
YET DEPENDING ON CLOUD COVER/PRECIP. THE COMBINATION OF ANOMALOUSLY
HIGH DEW PTS AND SFC TEMPS IN THE UPR 80S/NEAR 90 WOULD SIGNAL HEAT
INDEX VALUES IN THE MID/UPR 90S TO PERHAPS THE LOW 100S SOUTH OF
I-80...MAINLY FRI-SUN.
EARLY NEXT WEEK...
ENSEMBLES AND OPER SOLUTIONS CONTINUE TO POINT TOWARDS THE HOT/HUMID
AIRMASS BREAKING DOWN AND TRANSITIONING BACK TO A MID CONUS/GREAT
LAKES TROUGH. MON WILL LIKELY STILL BE A HOT/HUMID DAY. GUIDANCE HAS
DEMONSTRATED SOME CONFIDENCE/CONSISTENCY IN A FRONTAL BOUNDARY
APPROACHING THE REGION MON NGT/TUE...WITH MUCH COOLER AIR BEGINNING
TO DRIVE SOUTH ACROSS THE NORTHERN PLAINS TUE...AND ARRIVING ACROSS
THE CWFA TOWARDS THE MIDDLE OF NEXT WEEK.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* POSSIBLE LAKE BREEZE LATE WEDNESDAY AFTERNOON/EARLY EVENING.
KREIN
//DISCUSSION...UPDATED 09Z...
HAVE REMOVED MENTION OF MVFR VIS IN THE 09Z UPDATE. CONDITIONS
SHOULD REMAIN VFR AT THE TERMINALS OVERNIGHT.
WESTERLY WINDS INCREASE BY MID TO LATE MORNING WEDNESDAY WITH
MODEL FORECAST SOUNDINGS SUGGESTING PREVAILING WINDS AROUND 10
KT...ESPECIALLY DURG THE LATE MORNING HOURS. WINDS ARE EXPECTED TO
WEAKEN DURG BY THE LATE AFTERNOON HOURS AS A WEAK RIDGE AXIS
DEVELOPS FROM WISCONSIN...THROUGH NERN IL/NWRN IN INTO THE LOWER
OHIO VALLEY. A LAKE BREEZE IS EXPECTED TO DEVELOP NEAR THE LAKE
AND EVENTUALLY MOVE INLAND...BUT LIKELY NOT REACHING ORD/MDW UNTIL
LATE AFTERNOON OR EARLY EVENING. WINDS AT ORD/MDW SHOULD TURN
ESELY WITH THE PASSAGE OF THE LAKE BREEZE...BUT THERE WILL ONLY BE
A WEAK PUSH TO THE LAKE BREEZE AND THE SSELY WINDS SHOULD ONLY BE
ARND 5KT OR SO AT ORD/MDW. WINDS WILL THE SETTLE INTO A SSELY TO
SLY DIRECTION THROUGH THE LATE EVENING HOURS. ANOTHER MID LEVEL
IMPULSE IS EXPECTED TO DROP OUT OF THE UPPER MISSISSIPPI VALLEY
LATE WEDNESDAY NIGHT...BRINGING A CHANCE FOR MORE SHOWERS AND
THUNDERSTORMS TO THE REGION.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN WIND TRENDS THROUGH THE PERIOD...BUT A
LITTLE LOWER CONFIDENCE IN THE EXACT TIMING OF LAKE BREEZE
PASSAGE.
* LOW CONFIDENCE IN TIMING AND COVERAGE OF SHRA/TSRA WEDNESDAY
NIGHT.
KREIN
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
* THURSDAY THROUGH SATURDAY...CHANCE OF TSRA.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.
&&
.MARINE...
314 AM CDT
SFC LOW PRESSURE CONTINUES TO MEANDER AROUND NORTHERN LOWER
MICHIGAN THIS MORNING...ALTHOUGH HAS BEEN WEAKENING. THIS LOW IS
EXPECTED TO DRIFT SOUTHEAST AND REACH THE EASTERN GREAT LAKES
EARLY THURSDAY. OVER THE NEXT SEVERAL DAYS THE GRADIENT IS
EXPECTED TO BE VERY WEAK...SO MOST OF THE WINDS WILL BE LESS THAN
15KT. THIS WILL ALSO RESULT IN WAVES REMAINING LOW...OR GENERALLY
LESS THAN 3 FT IN MOST AREAS. WITH THUNDERSTORMS CHANCES OVER THE
NEXT SEVERAL DAYS...WINDS/WAVES WILL LIKELY BE ELEVATED IN AND
AROUND STORMS. OTHERWISE A SERIES OF WEAK LOW PRESSURE SYSTEMS
WILL MOVE FROM THE CENTRAL PLAINS NORTHEAST TO THE UPPER MIDWEST
INTO WESTERN ONTARIO.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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[top]
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
333 AM CDT Wed Aug 20 2014
.SHORT TERM...(Today and tonight)
ISSUED AT 333 AM CDT WED AUG 20 2014
Storms have developed along a boundary in northeast MO and southeast
IA early this morning. These storms should move into western and
southwest IL in the next several hours. These could get into western
parts of the CWA so will have some chance pops in the west this
morning. However, all models seem to indicate this area will not
travel very far and should dissipate during the morning hours. The
associated boundary will then slowly lift northeast as a warm front
through the CWA, and though convergence along this boundary will be
weak, some isolated showers or thunderstorms will remain possible in
the early afternoon. By late afternoon and into the evening and
overnight hours, the warm front will remain across the central part
of the CWA so the chance of showers and thunderstorms will continue
during the evening and overnight hours.
Temperatures will be a few degrees warmer than yesterday, with some
areas in the west and south getting to around 90. Overnight lows
will also be warmer as most of the CWA will be in the warm sector
overnight.
&&
.LONG TERM...(Thursday through Tuesday)
ISSUED AT 333 AM CDT WED AUG 20 2014
Position of the boundary after lifting through the FA today and
tonight will have a signif impact on the location of the showers and
thunderstorms. Though most recent models are lifting the boundary
further to the northeast, some chance pops Thurs and slight chance
pops remain in place at least over the northeastern portions of the
CWA from Thursday night through Friday night. Pops increasing
somewhat for Saturday as models are collapsing the ridge somewhat as
a wave moves over the ridge and into the Ohio River Valley. Though
the precip chances are scattered at best and low confidence...the
models have been very persistent with the very hot temperatures for
some summer like conditions that are well above normal for this time
of year. Models have also shown consistency with 850 mb temps in
the 19-25C range through Sunday. This will drive the temps into the
upper 80s/lower 90s with heat indices in the upper 90s/low 100s.
Forecast dwpts into the low to mid 70s may be over representing llvl
RH enhancement from widespread precip in the models that may not
quite come to fruition as widespread. Todays heat indices are more
borderline for Heat Advisory criteria...but far more likely to see
from Thursday into Sunday with subsequent forecasts, should the
trend continue. Into the extended, day 7/just into day 8, models
actually beginning to diverge into a solution to break down the
ridge with an upper system pushing a return of precip in for Tues
night into Wed.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 1145 PM CDT TUE AUG 19 2014
Skies clear across the TAF sites late this evening, but will see
some increase in clouds from the west late. Main concern is with
potential for fog. Latest short-range guidance suggesting the
KSPI-KCMI corridor most at risk for significant fog, as a weak
frontal boundary is draped in that area and dew points are pooling
along it. However, the increase in clouds near KSPI may help
mitigate the fog from getting out of control. The RAP model is
fairly robust with widespread dense fog affecting all the TAF
sites, but the HRRR has it more patchy within the KPIA/KSPI/KBMI
triangle. Right now, will go with a TEMPO period of 1SM at the
southern TAF sites and keep it a little higher further north,
where the air is a bit drier. Will also need to watch for
convection developing along the front in northern Missouri over
the next few hours. General thought is that this should stay
southwest of KSPI and will not mention at this time.
In the longer range of the TAF, concern is with timing of
convection late Wednesday afternoon and evening. NAM is faster and
much further south with storms moving through as early as 19-21Z,
while the latest GFS favors the evening hours, with other guidance
much more widely scattered but in the evening. Will favor the
later time frames with VCTS mention in the TAFs, although
confidence is somewhat uncertain at this time.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...AUTEN
LONG TERM...HJS
AVIATION...GEELHART
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
104 AM CDT WED AUG 20 2014
.DISCUSSION...
835 PM CDT
FOR EVENING UPDATE...
HAD ADJUSTED POPS/WX AND SKY COVER EARLIER BASED ON RADAR/SATELLITE
TRENDS. OTHER THAN DETAILS OF ENDING/MOVING ISOLATED SHRA OUT OF
NORTHEAST IL/NORTHWEST IN NEXT COUPLE OF HOURS...NO SIGNIFICANT
CHANGES MADE TO GOING FORECAST.
A FEW ISOLATED SHOWERS CONTINUE TO BUBBLE IN A COUPLE OF SPOTS AT
0115Z...ONE NEAR KANKAKEE...AND THE OTHER ACROSS NORTHERN COOK
COUNTY NEAR OHARE AND JUST OFF THE LAKE SHORE BETWEEN KENILWORTH AND
EVANSTON. THESE SHOWERS WERE OCCURRING ALONG A WEAK SURFACE TROUGH
AXIS WHICH STRETCHED FROM SOUTHERN LAKE MICHIGAN TO NORTH OF ST
LOUIS...AND AHEAD OF A MID-LEVEL SHORT WAVE TROUGH ROTATING EASTWARD
ACROSS NORTHWEST IL/WISCONSIN PER GOES VAPOR IMAGERY. THESE SHOWERS
HAVE DIMINISHED CONSIDERABLY IN COVERAGE WITH SUNSET AND THE
WEAKENING OF DIURNALLY-DRIVEN INSTABILITY...AND LINGERING SHOWERS
ARE EXPECTED TO CONTINUE TO WEAKEN AND DISSIPATE OR MOVE OVER LAKE
MICHIGAN IN THE NEXT HOUR OR TWO. STRONGER STORMS WHICH HAD FORMED
OVER PARTS OF EAST CENTRAL IL AND NORTHWEST INDIANA LATE THIS
AFTERNOON ALSO OCCURRED AHEAD OF A MORE COMPACT VORT MAXIMA SEEN
PUSHING EAST ACROSS CENTRAL IL AT THIS TIME... AND WITHIN A MORE
UNSTABLE ENVIRONMENT ASSOCIATED WITH POOLED UPPER 60S AND LOWER 70S
SURFACE DEW POINTS AHEAD OF THE SURFACE TROUGH. THESE STRONGER
STORMS HAVE MOVED OFF TO THE EAST OF THE CWA INTO CENTRAL AND
NORTHERN INDIANA. GOES 11-3.9 MICRON IR IMAGERY INDICATES LITTLE
LEFT OF DIURNAL CU FIELD ACROSS SOUTHERN WI/NORTHERN IL WEST OF
CHICAGO...SUGGESTING DRY CONDITIONS FOR THE MAJORITY OF THE AREA FOR
THE REMAINDER OF THE EVENING/OVERNIGHT HOURS. ANOTHER MID-LEVEL VORT
ROTATING SOUTH-SOUTHEASTWARD ACROSS CENTRAL MN HAS SOME ISOLATED
CONVECTION NEAR THE MSP AREA...AND HIGH-RES GUIDANCE DOES INDICATE
THE POTENTIAL FOR A FEW ISOLATED SHOWERS TO DEVELOP INTO NORTHEAST
IA/NORTHWEST IL TOWARD MORNING. STILL...APPEARS FAIRLY LOW CHANCE
WITH BETTER PRECIP POTENTIAL BECOMING FOCUSED BACK ACROSS
NEBRASKA/WESTERN IA BY MORNING.
HAD ADJUSTED POPS/WX AND SKY COVER EARLIER BASED ON RADAR/SATELLITE
TRENDS. OTHER THAN DETAILS OF ENDING/MOVING ISOLATED SHRA OUT OF
NORTHEAST IL/NORTHWEST IN NEXT COUPLE OF HOURS...NO SIGNIFICANT
CHANGES MADE TO GOING FORECAST.
RATZER
//PREV DISCUSSION...
304 PM CDT
WARMER AND MORE HUMID CONDITIONS ARE STILL EXPECTED AS WE GO THROUGH
THE REST OF THE WEEK WITH THE BIGGEST CHALLENGE BEING THE
DETERMINATION OF THE EXTENT OF SHOWER AND THUNDERSTORM ACTIVITY.
AFTERNOON WATER VAPOR IMAGERY SHOWS AN UPPER TROUGH OVERHEAD OF THE
LOCAL AREA MAKING GRADUAL PROGRESS TO THE EAST. BROAD LOW-AMPLITUDE
RIDGING IS IN PLACE OVER THE ROCKIES AND HIGH PLAINS WHILE A BROAD
UPPER TROUGH MOVES ACROSS WESTERN CANADA. A CUTOFF UPPER LOW IS
SPINNING SOUTHWARD DOWN THE CALIFORNIA COAST. THIS RIDGE/TROUGH
COMBINATION WILL AMPLIFY OVER THE NEXT FEW DAYS AND MAKE EASTWARD
PROGRESS. AT THE SURFACE...LOW PRESSURE IS OVER NORTHERN MICHIGAN IS
DRAGGING A COOL FRONTAL BOUNDARY/TROUGH SOUTHEAST ACROSS THE LOCAL
AREA.
TONIGHT AND WEDNESDAY...THE UPPER TROUGH OVER THE AREA TODAY WILL BE
SLOW TO MOVE EAST INTO WEDNESDAY KEEPING CYCLONIC FLOW OVERHEAD
THROUGH THE MORNING. THE BULK OF THE CONVECTIVE ACTIVITY IS NOW OFF
TO THE EAST WITH MORE SPOTTY DIURNALLY DRIVEN ACTIVITY WORKING INTO
THE NORTHERN CWA AND MAY SEE SOME ADDITIONAL ACTIVITY INTO CENTRAL
AREAS BEFORE DISSIPATING THIS EVENING. OTHERWISE...WATER VAPOR SHOWS
A WEAK WAVE ROUNDING THE PERIPHERY OF THE UPPER LOW OVER MINNESOTA
THIS AFTERNOON AND THIS SHOULD ROTATE OVER THE LOCAL AREA TONIGHT
AND MAY TRIGGER SOME ADDITIONAL SHOWERS. THE CHANCE DOES NOT LOOK
THAT GREAT ESPECIALLY WITH A MODESTLY DRIER AIRMASS IN PLACE BEHIND
THE AFTERNOON TROUGH. CYCLONIC FLOW REMAINS OVERHEAD WEDNESDAY
MORNING BUT SHIFTS TO THE EAST SO AM NOT EXPECTING PRECIP ACTIVITY
GIVEN THE POOR DIURNAL SUPPORT THEREFORE MUCH OF THE DAY WEDNESDAY
SHOULD BE DRY. HIGHS WILL WARM INTO THE LOW TO MID 80S BUT A LAKE
BREEZE SHOULD COOL LAKESHORE AREAS DURING THE AFTERNOON.
WEDNESDAY NIGHT THROUGH FRIDAY...THE UPPER RIDGE WILL MOVE FROM THE
HIGH PLAINS AND SLOW ITS EASTWARD PROGRESS OVER THE LOCAL AREA BY
FRIDAY. IT WILL AMPLIFY AS IT MOVES EASTWARD HELPING TO SHARPEN THE
ASSOCIATED MID LEVEL BAROCLINIC ZONE WHICH WILL MOVE NORTHEAST
ACROSS THE FORECAST AREA STARTING BY WEDNESDAY EVENING. WITH A
STRONG PUSH OF MOISTURE AND A WEST TO SOUTHWEST LOW LEVEL JET
DEVELOPING WEDNESDAY EVENING SHOULD SEE A DECENT COVERAGE OF SHOWERS
AND THUNDERSTORMS DEVELOP AND MOVE ACROSS THE AREA INTO THURSDAY
MORNING. BETTER ORGANIZATION COULD RESULT WITH THE PASSAGE OF ANY
SHORTWAVE EJECTING FROM THE AMPLIFYING BUT STILL BROAD WESTERN
TROUGH. LESS CONFIDENT IN PRECIP CHANCES FROM LATE THURSDAY THROUGH
FRIDAY AS THE RIDGE AXIS WILL BE OVER THE AREA BUT THE RIDGE LOOKS
TO BE BROAD ENOUGH THAT THE MORE ACTIVE FLOW AROUND THE PERIPHERY
WILL BE IN CLOSE PROXIMITY. ULTIMATELY A WARM FRONTAL BOUNDARY WILL
LIKELY SET UP TO THE NORTH EXTENDING FROM LOW PRESSURE ACROSS THE
CENTRAL/NORTHERN PLAINS BUT CONVECTION MAY INFLUENCE HOW FAR
NORTH-SOUTH THIS BOUNDARY MOVES WHICH WILL AFFECT POPS AND POSSIBLY
TEMPS AS WELL. WILL CONTINUE WITH THE IDEA OF THE BOUNDARY REMAINING
NORTH LEADING TO HIGHS IN THE MID AND UPPER 80S THURSDAY AND UPPER
80S TO AROUND 90 FRIDAY. THE FLOW MAY BE WEAK ENOUGH TO ALLOW SOME
LAKE INFLUENCE TO COOL SHORELINE AREAS SOMEWHAT. ANY OUTFLOW FROM
STORMS OVER OR NORTH OF THE AREA COULD IMPACT TEMPS AS WELL.
SATURDAY AND BEYOND...THE WESTERN TROUGH WILL EVENTUALLY TRACK EAST
ACROSS THE NORTHERN PLAINS BREAKING DOWN THE RIDGE BUT THE SPEED
WITH WHICH THIS OCCURS IS STILL IN QUESTION. AT THIS POINT THE RIDGE
LOOKS TO FURTHER AMPLIFY OVER THE WEEKEND WHICH COULD KEEP THINGS
DRY BUT GUIDANCE HAS FLUCTUATED ON THE AMPLITUDE. WILL KEEP LOW POPS
SATURDAY AND SUNDAY...MAINLY NORTH CLOSER TO THE MORE ACTIVE FLOW
AROUND THE TOP OF THE RIDGE. TEMPS IN THE UPPER 80S TO AROUND 90
WILL CONTINUE ALONG WITH THE HUMIDITY. AS THE UPPER TROUGH MOVES
EAST SURFACE LOW PRESSURE WILL LIKELY DEVELOP ACROSS THE NORTHERN
PLAINS AND DRAG A COLD FRONT INTO THE AREA EARLY NEXT WEEK. THE
OVERALL UPPER PATTERN WILL BE DE-AMPLIFYING SO THE FRONT MAY STALL
OUT SOMEWHERE NEAR THE AREA BUT STILL QUITE A WAYS OUT THERE FOR ANY
KIND OF CONFIDENCE IN THIS.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* CHANCE MVFR VIS OVERNIGHT INTO EARLY WEDNESDAY MORNING.
* POSSIBLE LAKE BREEZE LATE WEDNESDAY AFTERNOON/EARLY EVENING.
KREIN
//DISCUSSION...UPDATED 06Z...
ALL CONVECTIVE ACTIVITY HAS MOVED OUT OF NRN IL/NWRN IN AND SKIES
HAVE BECOME MOSTLY CLEAR WITH CALM TO LIGHT WEST WINDS. CLEAR
SKIES LIGHT WINDS AND DEWPOINTS IN THE 60S SHOULD ALLOW FOR SOME
FG/BR DEVELOPMENT AS TEMPERATURES RADIATE DOWN CLOSE TO THE IN
SITU DEWPOINTS. WILL CARRY MVFR VIS AT ALL TERMINAL EXCEPT ORD/MDW
WHERE URBAN HEAT ISLAND EFFECTS COULD KEEP TEMPS A LITTLE
HIGHER...AND SATURATION WOULD BE LESS LIKELY. A FEW ISOLD POCKETS
OF IFR VIA ARE POSSIBLE IN LOW LYING...SHELTERED LOCATIONS.
WESTERLY WINDS INCREASE BY MID TO LATE MORNING WEDNESDAY WITH
MODEL FORECAST SOUNDINGS SUGGESTING PREVAILING WINDS AROUND 10
KT...ESPECIALLY DURG THE LATE MORNING HOURS. WINDS ARE EXPECTED TO
WEAKEN DURG BY THE LATE AFTERNOON HOURS AS A WEAK RIDGE AXIS
DEVELOPS FROM WISCONSIN...THROUGH NERN IL/NWRN IN INTO THE LOWER
OHIO VALLEY. A LAKE BREEZE IS EXPECTED TO DEVELOP NEAR THE LAKE
AND EVENTUALLY MOVE INLAND...BUT LIKELY NOT REACHING ORD/MDW UNTIL
LATE AFTERNOON OR EARLY EVENING. WINDS AT ORD/MDW SHOULD TURN
ESELY WITH THE PASSAGE OF THE LAKE BREEZE...BUT THERE WILL ONLY BE
A WEAK PUSH TO THE LAKE BREEZE AND THE SSELY WINDS SHOULD ONLY BE
ARND 5KT OR SO AT ORD/MDW. WINDS WILL THE SETTLE INTO A SSELY TO
SLY DIRECTION THROUGH THE LATE EVENING HOURS. ANOTHER MID LEVEL
IMPULSE IS EXPECTED TO DROP OUT OF THE UPPER MISSISSIPPI VALLEY
LATE WEDNESDAY NIGHT...BRINGING A CHANCE FOR MORE SHOWERS AND
THUNDERSTORMS TO THE REGION.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN WIND TRENDS THROUGH THE PERIOD...BUT A
LITTLE LOWER CONFIDENCE IN THE EXACT TIMING OF LAKE BREEZE
PASSAGE.
* MEDIUM TO HIGH CONFIDENCE THAT VIS WILL DROP TO MVFR WITH ISOLD
IFR ACROSS THE REGION...AND MEDIUM CONFIDENCE THAT VIS AT
ORD/MDW WILL REMAIN 6SM OR HIGHER.
* LOW CONFIDENCE IN TIMING AND COVERAGE OF SHRA/TSRA WEDNESDAY
NIGHT.
KREIN
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
* THURSDAY THROUGH SATURDAY...CHANCE OF TSRA.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.
&&
.MARINE...
319 PM CDT
GENERALLY QUIET CONDITIONS OVER THE LAKE THROUGH THE WEEKEND WITH
RESPECT TO WINDS AND WAVES...AND PERIODS WHERE DIRECTIONS IN THE
NEARSHORE AREAS WILL BE CONTROLLED BY LAKE BREEZE INFLUENCES BY
DAY. A WARM AND MOIST AIR MASS WILL OVERSPREAD THE REGION AND
UPPER LEVEL DISTURBANCES COULD RESULT IN THUNDERSTORM COMPLEXES
CROSSING THE LAKE AT TIMES...MAINLY FROM WEDNESDAY NIGHT THROUGH
SATURDAY. THE POTENTIAL EXISTS FOR SOME OF THESE COMPLEXES TO
PRODUCE GUSTY WINDS AND LOCALLY HIGHER WAVES...AS WELL AS FREQUENT
CLOUD TO WATER LIGHTNING.
RC
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1200 AM CDT Wed Aug 20 2014
.UPDATE...
ISSUED AT 830 PM CDT TUE AUG 19 2014
Weak frontal boundary currently extending from northeast Illinois
through the Galesburg area to far northern Missouri. Earlier
convection has pushed well to the east and skies are now mostly
clear in our area, although some rogue thunderstorms have recently
developed along an outflow boundary across Clark County. Not any
appreciable change in temperature on either side of the front, but
dew points are slightly lower to the north. Front is not expected
to make much additional headway overnight. HRRR and RAP showing
some additional convection developing overnight on the tail of the
front across northern Missouri southeast to near St Louis.
Currently think the precip should stay to our southwest, but will
see an increase in clouds after midnight across the southwest CWA.
&&
.SHORT TERM...(This evening through Wednesday)
ISSUED AT 256 PM CDT TUE AUG 19 2014
19z/2pm surface analysis shows slow-moving cold front along the
Mississippi River. Isolated showers and thunderstorms are beginning
to develop immediately along the boundary within a narrow uncapped
instability axis. Further east, the air mass across much of central
Illinois remains capped in the wake of convection that moved across
the area earlier in the day. Will hold on to slight chance PoPs
through the early evening as the front makes its way slowly eastward
into the KILX CWA. Once daytime instability is lost, will go with a
dry forecast across the board overnight. With the boundary in the
vicinity, winds will become light/variable tonight, setting up the
possibility of fog. Forecast soundings suggest low-level moisture
will remain high, with both the MET and MAV guidance indicating
reduced visbys. Based on this guidance and a persistence forecast
from the past couple of nights, have included patchy fog after
midnight. Weak frontal boundary will remain in the area on
Wednesday, resulting in a continued slight chance for
showers/thunder, with afternoon highs climbing into the middle to
upper 80s.
&&
.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 256 PM CDT TUE AUG 19 2014
Wednesday night after midnight had previously looked like our best
chances of storms over the next few days, but the 12z guidance has
sped up the shortwave/MCV by 6-12 hours and weakened it. Our area
will still remain along the storm track over the building upper
level ridge, so despite lowering PoPs below the likely category,
chances will remain in most areas, with lowest chances southwest of
Springfield to Effingham.
The theme of higher storm chances in N-NE Illinois will continue for
the balance of the extended forecast, as the upper ridge and dome of
hot air build from southwest to northeast. The storm track appears
to generally follow the 588dm 500mb height line into this weekend.
We kept a narrow channel of chance PoPs across our N-NE counties
from Thursday to Saturday, with minor shifts east and west during
that time. Slight chances could extend as far south as Rushville to
Lincoln to Mattoon, but the building dome of heat should provide
enough mid-level capping to limit the southward extent of storms.
Model differences in the Sunday to Tuesday time frame have prompted
a continuation of periodic slight chance PoPs as a cold frontal
boundary tries to push into the dome of hot air. The 12z runs have
limited the forward progression of the front into IL on Sunday night
and Monday, when previous runs indicated an air mass change for less
hot conditions on Monday. Now the heat may linger as long as Tuesday
with the only hints of relief coming for areas north of I-74.
Heat index readings from Wednesday to Sunday will climb to into the
95F to 102F range at peak heating, which could be locally limited by
any pop-up thunderstorms each afternoon. Heat advisory levels are
105F+, but conditions will still be very uncomfortable, and heat
precautions will be necessary each day.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 1145 PM CDT TUE AUG 19 2014
Skies clear across the TAF sites late this evening, but will see
some increase in clouds from the west late. Main concern is with
potential for fog. Latest short-range guidance suggesting the
KSPI-KCMI corridor most at risk for significant fog, as a weak
frontal boundary is draped in that area and dew points are pooling
along it. However, the increase in clouds near KSPI may help
mitigate the fog from getting out of control. The RAP model is
fairly robust with widespread dense fog affecting all the TAF
sites, but the HRRR has it more patchy within the KPIA/KSPI/KBMI
triangle. Right now, will go with a TEMPO period of 1SM at the
southern TAF sites and keep it a little higher further north,
where the air is a bit drier. Will also need to watch for
convection developing along the front in northern Missouri over
the next few hours. General thought is that this should stay
southwest of KSPI and will not mention at this time.
In the longer range of the TAF, concern is with timing of
convection late Wednesday afternoon and evening. NAM is faster and
much further south with storms moving through as early as 19-21Z,
while the latest GFS favors the evening hours, with other guidance
much more widely scattered but in the evening. Will favor the
later time frames with VCTS mention in the TAFs, although
confidence is somewhat uncertain at this time.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEELHART
SHORT TERM...BARNES
LONG TERM...SHIMON
AVIATION...GEELHART
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1138 PM CDT TUE AUG 19 2014
.SYNOPSIS...
ISSUED AT 305 PM CDT TUE AUG 19 2014
WEAK HIGH PRESSURE OVER IOWA WILL MOVE EAST AS A WARM FRONT
DEVELOPS TO THE SOUTH AND BEGINS TO LIFT NORTH TONIGHT. THE FRONT
WILL LIFT NORTH OF THE STATE ON WEDNESDAY NIGHT. STRONG S/WV WILL
MOVE UP THE BACK SIDE OF THE UPPER LEVEL RIDGE AND PUSH A COLD
FRONT ACROSS THE STATE THIS WEEKEND.
&&
.SHORT TERM /TONIGHT/...
ISSUED AT 305 PM CDT TUE AUG 19 2014
A SURFACE LOW DEVELOPING OVER NORTHEAST COLORADO WILL SHIFT INTO
NORTHWEST NEBRASKA OVERNIGHT. AN ASSOCIATED WARM FRONT WILL EXTEND
FROM THE LOW THROUGH EASTERN NEBRASKA AND INTO SOUTHWEST IOWA AND
NORTHERN MISSOURI BY 12Z WEDNESDAY BEFORE SURGING NORTH THROUGH THE
DAY WEDNESDAY. STRONG THETA-E ADVECTION IS FORECAST TO LIFT ACROSS
CENTRAL IOWA DURING THE OVERNIGHT HOURS...ESPECIALLY AFTER 06Z.
FORCING IS WEAK BUT DOES IMPROVE OVERNIGHT AS A LOW LEVEL JET
FOCUSES INTO SOUTHWEST IOWA. ALOFT A WEAK SHORTWAVE IS PROGGED TO
MOVE ACROSS EASTERN NEBRASKA/SOUTHWEST IOWA. THIS SHOULD BE ENOUGH
TO PRODUCE SHOWERS AND THUNDERSTORMS ACROSS SOUTHWEST INTO CENTRAL
IOWA. STORMS SHOULD MAINLY BE ELEVATED AS LOW LEVEL CONVERGENCE IS
WEAK TO NON EXISTENT. THERE IS ALSO SOME WEAK SHEAR...PERHAPS
ENOUGH FOR AN ISOLATED STORM TO BRIEFLY PRODUCE SOME MARGINALLY
SEVERE TO SEVERE HAIL. THE HIGH RES AND NAM12 MODELS ARE NOT AS
IMPRESSIVE WITH DEVELOPING STORMS ACROSS THE AREA BUT THE SREF DOES
AS DOES PREVIOUS RUN OF THE HI-RES MODELS. THE HRRR IN PARTICULAR
IS FAIRLY BULLISH ON BRINING PRECIP INTO THE SW WHILE THE MEMBERS OF
THE HOPWRF ARE A LITTLE MORE RESERVED...AT LEAST THROUGH 09Z.
SOME POTENTIAL FOR FOG ACROSS THE NORTHEAST OVERNIGHT AS REMAINING
CLOUDS ACROSS THE AREA DISSIPATE WITH SUNSET AND SURFACE RIDGING
MOVES OVERHEAD PRODUCING LIGHT WIND. NOT LOOKING AT DENSE FOG AT
THIS POINT GIVEN THE VERY SHALLOW NATURE OF THE MOISTURE MOVING IN.
GENERALLY WENT WITH PATCHY FOG WORDING HOWEVER ALO/MCW WILL BE EAST
OF THE RIDGE AXIS AND MOISTURE COULD BE ENOUGH FOR A LITTLE MORE
WIDESPREAD FOG SO I MENTION AREAS OF FOG OVER THESE LOCATIONS.
.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
ISSUED AT 305 PM CDT TUE AUG 19 2014
A BREAK IN THE CONVECTION IS EXPECTED ON WED AS THE FIRST ROUND OF
THETA-E ADVECTON LIFTS OUT OF THE STATE. A RENEWED THREAT OF
THUNDERSTORMS WILL COME AS THE WARM FRONT LIFTS NORTH AND STRONG
THETA-E ADVECTION TAKES PLACE WED NIGHT. THE H8 SHOWS GOOD SPEED
CONVERGENCE AND THERE IS DIVERGENCE ALOFT...THE FLY IN THE
OINTMENT WILL BE IF THE ATMOSPHERE CAPS OFF OR NOT. AN EML IS IN
PLACE...BUT IT IS NOT ALL THAT STRONG.
WARM AND HUMID WEATHER WILL HOLD INTO THE WEEKEND WITH AFTERNOON
HEAT INDICES IN THE LOW TO MID 90S NORTH...AND 95 TO 105 SOUTH
TUE-THU AFTERNOON. BELOW CRITERIA...BUT WILL MENTION IN THE HWO
WITH ALL THE SCHOOL ACTIVITIES GOING ON.
COOLER WEATHER WILL MOVE IN OVER THE WEEKEND...FIRST DUE TO THE
INCREASED CLOUD COVER...THEN DUE TO THE FRONTAL PASSAGE SAT. COOL
AIR WILL SETTLE IN SLOWLY WITH TEMPS FALLING BELOW NORMAL; FOR MON
AND TUE.
&&
.AVIATION...20/06Z
ISSUED AT 1134 PM CDT TUE AUG 19 2014
BOUNDARY WILL LIFT ACROSS IOWA THROUGH WEDNESDAY...THIS WILL BRING
CHANCES FOR SHRA/TSRA TO SITES...PRIMARILY SOUTHERN SITES
THROUGHOUT THE PERIOD. BEST CHANCES WILL COME BEFORE 12Z...BEFORE
DECREASING. HAVE INCLUDED VC MENTION AT KFOD/KDSM/KOTM. NORTHERN
SITES WILL LIKELY SEE BR/FG NEAR 12Z GIVEN AMPLE LOW LEVEL
MOISTURE. MVFR...IFR OR LOWER CEILINGS AND VISIBILITIES WILL BE
POSSIBLE AT TIMES AT SITES THROUGH 12Z BEFORE IMPROVING QUICKLY
AFTER 12Z. WINDS WILL BECOME SOUTHERLY AND CONDITIONS WILL REMAIN
VFR THROUGH REMAINDER OF PERIOD.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MS AUG 14
SHORT TERM...FAB
LONG TERM...MS AUG 14
AVIATION...AWB
AREA FORECAST DISCUSSION
NWS TOPEKA KS
319 AM CDT Wed Aug 20 2014
.SHORT TERM...(Today and Tonight)
Issued at 234 AM CDT WED AUG 20 2014
Large-scale pattern over the Plains becoming more of a dirty ridge
regime with at to somewhat above normal precipitable water levels
across the bulk of the CONUS. Main troughs were over western North
America and the Great Lakes, with a minor upper wave in east central
Texas and 0Z observations showing a mid level trough over west
Texas. Since last night at this time, warm air advection and deep
moisture convergence has shifted northeast into Iowa where overnight
convection has erupted.
The Texas waves should be weakening with time with rather warm
column leading to limited saturation despite modestly above normal
PWs. Mid afternoon to evening hours exhibit little convective
inhibition but hard to think anything more than isolated storms
could result given limited forcing. Lower thermal fields showing
overall little change from Tuesday, with even minor cooling
suggested in some areas. Better mixing in the tighter surface
gradient and mixing of the 30-40kt low level jet should more than
offset any high cloud for highs to reach the mid to upper 90s again
with heat index values a few degrees higher yet. A slightly stronger
low level develops tonight, and with another day of heat today
expect temps to only fall into the mid to upper 70s.
.LONG TERM...(Thursday through Tuesday)
Issued at 234 AM CDT WED AUG 20 2014
Thursday and Friday the heat continues across the forecast area as
upper ridge slowly builds northward toward the upper Midwest.
850mb temps of 24-26c nose eastward out of the high plains into
eastern Kansas which brings surface temperatures well into the
upper 90s across most of the area. Longwave upper trof continues
to move eastward into the northern Rockies, with shortwave trof
moving into the upper Midwest late Thursday. Will keep low end
pops across the KS NE border where trailing front and nocturnal
llj may bring convection that far south although chances are
better farther north. Similar scenario plays out again in the
overnight hours Friday night.
Subtle differences in the larger scale pattern influence the
forecast through the weekend. EC is more pronounced with the
upper ridge into eastern Kansas, while the GFS flattens the ridge
more as energy moves out of the upper trof into the northern
Plains. How far east clouds and rain chances can extend east and
south will impact sensible weather through the weekend. Started
to bring rain chances farther east and south by Sunday, which leans
towards the GFS, but the strength of the ridge could certainly end
up toward a warmer drier EC solution on Sunday. North central
counties have better chances than farther east in this transition
period. Hopefully by Monday into Tuesday the longwave trof will
have made enough eastward progress to bring better rain chances
and a cooling trend in temperatures to our area. Worth noting
that both EC and GFS have a tropical system moving off the Mexico
coast by the end of the forecast period, which would likely
influence moisture transport into the longwave trof to its north
and could help rain chances for the forecast area. Have a slow
cooling in high temperatures from 90s on Saturday to low/middle
90s Sunday and back into the 80s for Monday and Tuesday.
Increasing rain chances by Monday and Tuesday with overnight lows
still on the warm side with 70s over the weekend to upper 60s by
Monday night.
&&
.AVIATION...(For the 06Z TAFs through 06Z Wednesday Night)
Issued at 1136 PM CDT TUE AUG 19 2014
Models continue to depict the best convergence on the nose of the
low level jet to stay just north and east of the forecast area.
Therefore will maintain a VFR forecast. RAP and NAM forecast
soundings continue to support the possibility for some LLWS and
profiler data is starting to show the winds at 925MB strengthen.
So will maintain the mention of wind shear. Additionally the RAP
and NAM show a decent pressure gradient developing by Wednesday
afternoon with dry adiabatic low level lapse rates and good
mixing. Because of thin think south winds will become gusty by the
afternoon.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...65
LONG TERM...67
AVIATION...Wolters
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1136 PM CDT Tue Aug 19 2014
...AVIATION UPDATE...
.SHORT TERM...(This Evening through Wednesday)
Issued at 342 PM CDT TUE AUG 19 2014
An upper level trough was moving east across the upper Midwest and
mid MS river valley late this afternoon. An upper level ridge across
NM and CO will build east across the plains tonight and east into
the lower and mid MS river valley by late Wednesday afternoon.
Any convective complexes that form across the central and northern
high plains this evening should move well north of the CWA tonight.
Isentropic lift will cause elevated storms to form across southeast
SD and eastern NE but these storms will move east into IA.
Wednesday will be mostly sunny and warm as the upper level ridge
axis moves east across the state of KS. Highs will reach the mid to
upper 90s, with highs of 100 degrees possible across the southwest
counties of the CWA. Deeper mixing across the western counties
should cause dewpoints to drop into the mid 60s during the afternoon
hours. The northeast counties may keep lower 70 dewpoints through
the afternoon hours but high temperatures will be slightly cooler in
the mid 90s. Heat indices will range from 100 to 104 degrees across
the CWA during the afternoon hours.
.LONG TERM...(Wednesday Night through Tuesday)
Issued at 342 PM CDT TUE AUG 19 2014
The GFS is the only model hinting at clipping the far northwest
county warning area with convection Wednesday night despite forecast
soundings showing inhibition aloft through the night. Will therefore
maintain a dry forecast through Thursday morning as the shortwave
helping to develop precip should pass well north and west of the
CWA. Another shortwave trough over the southern Rockies will move
northeast and bring a chance for thunderstorms to the northwest
third of the CWA Thursday night...although again the better chances
will remain well north and west of the CWA.
Following this wave...the ridging with the upper level high will
undergo amplification as the stronger shortwave trough begins to
rotate out of the case of the western trough and into the
central/southern Rockies. Although this should keep the CWA dry and
hot on Friday...it may allow for some of the high plains convection
that forms late in the day to spread east and northeastward and
briefly clip the CWA Friday night. Highs Thursday through Saturday
will generally be in the middle to upper 90s.
Models differ some with the overall timing/speed of the final
shortwave to rotate out through the western trough and into the
central plains next week. However they are similar in bringing the
western trough slowly eastward into the ridge and gradually
flattening it with time. This will result in one front moving into
the CWA by Monday with a second arriving by Wednesday. This will
keep the chances for showers and thunderstorms across most of the
area Sunday thru Tuesday. With more clouds...precip chances and
initial front...cooled high temperatures slightly for now into the
80s and lower 90s. At the same time...cooled lows in the middle 70s
Thursday and Friday into the 60s by Monday and Tuesday.
&&
.AVIATION...(For the 06Z TAFs through 06Z Wednesday Night)
Issued at 1136 PM CDT TUE AUG 19 2014
Models continue to depict the best convergence on the nose of the
low level jet to stay just north and east of the forecast area.
Therefore will maintain a VFR forecast. RAP and NAM forecast
soundings continue to support the possibility for some LLWS and
profiler data is starting to show the winds at 925MB strengthen.
So will maintain the mention of wind shear. Additionally the RAP
and NAM show a decent pressure gradient developing by Wednesday
afternoon with dry adiabatic low level lapse rates and good
mixing. Because of thin think south winds will become gusty by the
afternoon.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...Gargan
LONG TERM...63
AVIATION...Wolters
AREA FORECAST DISCUSSION
NWS JACKSON KY
357 AM EDT WED AUG 20 2014
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 357 AM EDT WED AUG 20 2014
A COMPLEX OF SHOWERS AND THUNDERSTORMS IS CURRENTLY SLIDING EAST
ACROSS THE OHIO VALLEY ASSOCIATED WITH A PASSING SHORT WAVE TROUGH.
THE MORE ORGANIZED PORTION OF THIS COMPLEX HAS BEEN CONFINED TO ALONG
AND NORTH OF THE MOUNTAIN PARKWAY. THE HRRR MODEL HAS NOT BEEN
HANDLING THIS FEATURE WELL THROUGH THE OVERNIGHT...OVERPLAYING THE
DEVELOPMENT TO THE SOUTH THAT HAS BEEN WEAK IN REALITY...WHILE
UNDERPLAYING WHERE CONVECTION HAS BEEN MORE ORGANIZED AND SUSTAINED.
EXPECT THIS COMPLEX TO KEEP MOVING EAST...AFFECTING LOCATIONS ALONG
AND NORTH OF THE MOUNTAIN PARKWAY FOR THE NEXT FEW HOURS...BEFORE
EXITING THE AREA BY 12Z. THERE WILL BE SOME SUBSIDENCE FOLLOWING THIS
DEPARTING SHORT WAVE FOR TODAY WORKING IN FROM WEST TO EAST...SO HAVE
TRIMMED THE POPS BACK A BIT...PEAKING IN THE 20 TO 30 RANGE FOR MOST
LOCATIONS DURING THE HOTTER PART OF THE DAY. HIGHS TODAY WILL RANGE
FROM 85 TO 90 DEGREES.
AS WE HEAD INTO TONIGHT...CONVECTION WILL BE ON THE DOWNWARD TREND
THROUGH 06Z...BUT THEN LOOKS TO INCREASE BETWEEN 06 AND 12Z...AS
ANOTHER SHORT WAVE TROUGH APPROACHES FROM THE NORTHWEST. POP CHANCES
WILL CONTINUE TO INCREASE THROUGH THE DAY ON THURSDAY WITH HEATING
AIDING THE MODEST FORCING FROM THE PASSING SHORT WAVE. HAVE MAINTAINED
THE BETTER POPS IN THE NORTHEAST...AND LESSER VALUES IN THE
SOUTHWEST...FURTHER REMOVED FROM THE BETTER FORCING. HIGHS WILL
RETURN TO THE 85 TO 90 DEGREE RANGE IN THE SOUTHWEST...WITH MID 80S
IN THE NORTHEAST...WHERE MORE PERSISTENT CLOUD COVER WILL RESIDE.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 335 AM EDT WED AUG 20 2014
THE EXTENDED PORTION OF THE FORECAST BEGINS ON THURSDAY NIGHT WITH A
SLOWLY BUILDING RIDGE OVER THE CENTRAL CONUS AND DIGGING TROUGHS
OVER THE NORTHWEST AND NORTHEAST. THIS GENERAL TREND CONTINUES
THROUGH THE ENTIRE EXTENDED PERIOD. DURING THIS PERIOD...QUITE A FEW
STRONG SHORTWAVES TRAVEL OVER THE BUILDING RIDGE IN THE CENTRAL
PLAINS AND INTO THE OH VALLEY AND GREAT LAKES REGION. THE FIRST WAVE
OF NOTE WILL BE THE SHORTWAVE MOVING THROUGH AT THE BEGINNING OF THE
EXTENDED. AFTER THIS...THE PATTERN TURNS INTO A MORE MCS DRIVEN
PATTERN FRIDAY THROUGH SUNDAY WITH ACTIVITY CENTERED AROUND WHAT THE
DAYS CONVECTION BRINGS AND IS DIURNALLY AFFECTED. THROUGH THE PERIOD
THE UPPER RIDGE SLOWLY WEAKENS AND DRIFTS EAST.
CONCERNING THE MODELS DURING THE EXTENDED...THE GFS AND EURO LOOK TO
BE RIGHT ON TRACK AND IN GOOD AGREEMENT. THOUGH...THE EURO LOOKS TO
CUT OFF ANY CONVECTION BY THE END OF THE EXTENDED AS THE RIDGE AXIS
SETS UP RIGHT OVER EASTERN KENTUCKY LEADING TO AN END TO ALL
DIURNALLY DRIVEN CONVECTION AND DISPLACING THE TRACK OF THE MCS MORE
TO THE NORTHEAST. BASED ON THE GOOD AGREEMENT...IT SEEMS TO BE A
GOOD CONSENSUS TO STAY CLOSE TO THE SOLUTION OF THE ALL BLEND MODEL.
THOUGH DEPENDING ON WHAT THE 00Z EURO DOES ON THE MONDAY AND TUESDAY
TIME FRAME FOR THE RIDGE AXIS RIGHT OVER THE AREA...MAY DROP POPS
BELOW THE ALL MODEL BLEND SOLUTION. WITH THE SOLUTION OF THE ALL
MODEL BLEND...THE BEST CHANCE OF POPS WILL BE DURING THE FRIDAY
THROUGH SUNDAY TIME FRAME AND LESS DURING THE MONDAY AND TUESDAY
TIME FRAME WHERE THE RIDGE WILL BE OVER EASTERN KENTUCKY AND HAVE
LEFT SLIGHT CHANCE MAINLY DURING THE AFTERNOON ON MONDAY AND
TUESDAY.
IN ADDITION TO THIS PATTERN...TEMPERATURES WILL BE ON THE INCREASE
IN EARNEST AS SOME OF THE WARMEST WEATHER OF THE ENTIRE SUMMER WILL
BEGIN TO SET IN FROM FRIDAY THROUGH THE REST OF THE EXTENDED. HIGH
TEMPERATURES WILL SURPASS 90 DEGREES IN SOME AREAS OF EASTERN
KENTUCKY AND HUMIDITY WILL BE ON THE INCREASE AS WELL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 235 AM EDT WED AUG 20 2014
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL WORK THEIR WAY
FROM WEST TO EAST ACROSS EASTERN KENTUCKY THROUGH DAWN. AREAS ALONG
AND NORTH OF THE I-64 CORRIDOR WILL SEE THE BEST CHANCE OF THE MORE
CONCENTRATED CONVECTION. AS SUCH...HAVE HANDLED MOST OF THIS ACTIVITY
WITH VCTS/VCSH AS SOME OF THIS ACTIVITY WILL LIKELY WEAKEN AS IT
HEADS EAST. EXPECT MVFR/IFR FOG TO SET IN BETWEEN 08 AND 12Z AS
WELL...WITH THE DEEPER RIVER VALLEYS ALONG WITH ANY LOCATIONS THAT
SEE MORE SUSTAINED RAINFALL SEEING IFR OR WORSE FOG. THERE SHOULD BE
A CONVECTIVE LULL IN THE MORNING...BEFORE SOME ISOLATED STORMS MAY
THREATEN AGAIN IN THE AFTERNOON.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GEOGERIAN
LONG TERM...SHALLENBERGER
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
133 AM EDT WED AUG 20 2014
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 422 PM EDT TUE AUG 19 2014
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW FROM WRN
LAKE SUPERIOR INTO W UPPER MI. A SHORTWAVE NEAR THE LOW CENTER
SUPPORTED AN AREA OF SHOWERS...SOME LOCALLY HEAVY...THROUGH CNTRL
UPPER MI. WITH THE SLOW FORWARD MOVEMENT...PWAT AROUND 1.5
INCHES...AND EFFICIENT WARM RAIN PROCESSES...NEARLY 2.0 INCHES OF
RAIN FELL AT THE NWS OFFICE BTWN 1915Z-1945Z. AN FLS WAS ISSUED TO
HIGHLIGHT THREAT FOR MINOR FLOODING WITH SMALL STREAMS AND LOW-LYING
AREAS. AT THE SFC...LOW PRES WAS LOCATED OVER NW UPPER MI.
EXPECT THE VERTICALLY STACKED LOW TO ONLY SLOWLY WOBBLE TO THE EAST
TO CNTRL/EAST UPPER MI BY 12Z/WED AND TO NEAR THE STRAITS BY 00Z/THU.
THERE WILL BE A CONTINUED THREAT FOR SOME LOCALLY HEAVY RAIN WITH
THE SHRTWV MOVING THROUGH CNTRL UPPER MI THIS EVENING.
ONLY ISOLD TSRA ARE EXPECTED...GIVEN AFTERNOON TRENDS AND MUCAPE BLO
1K J/KG.
OTHERWISE...HIGH RES MODELS AND UPSTREAM RADAR TRENDS SUGGEST RAIN
WILL BECOME MORE SCATTERED THIS EVENING AND DIMINISH FURTHER
OVERNIGHT. WITH ABUNDANT DEEP MOISTURE REMAINING OVER THE REGION
THROUGH WED MORNING...SOME SCT LIGHT SHOWERS OR DRIZZLE WILL REMAIN
POSSIBLE THROUGH THE MORNING...ESPECIALLY OVER THE N CNTRL AND EAST
EVEN WITH WEAK FORCING NEAR THE LOW. HOWEVER...ANY ADDITIONAL
RAINFALL AMOUNTS SHOULD BE LIGHT...LESS THAN A TENTH OF AN INCH.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 402 PM EDT TUE AUG 19 2014
THE UPPER LEVEL WAVE AND ASSOCIATED WEAK LOW PRESSURE SYSTEM THAT
ARE CURRENTLY OVER THE AREA WILL CONTINUE TO INFLUENCE THE UPPER
GREAT LAKES REGION INTO WEDNESDAY BEFORE PULLING OUT ON WEDNESDAY
NIGHT. AS THIS WAVE PULLS OUT...SHOULD SEE A DRY PERIOD OVER MUCH
OF THE U.P. FOR WEDNESDAY NIGHT INTO THURSDAY MORNING (ALTHOUGH
THERE COULD BE SOME LINGERING SHOWERS OVER THE NORTHEAST ON
WEDNESDAY EVENING) BEFORE THE NEXT WAVE ARRIVES THURSDAY AFTERNOON
AND REMAINS INTO FRIDAY. THE DRY PERIOD WILL BE AIDED BY THE WEAK
RIDGING ALOFT THAT WILL MOVE INTO THE UPPER GREAT LAKES REGION AND
ATTEMPT TO BUILD INTO THE GREAT LAKES REGION THROUGH THE WEEKEND.
AS THAT RIDGING OCCURS...AN UPPER TROUGH WILL ESTABLISH ITSELF
OVER THE NORTHERN ROCKIES AND EJECT OUT A COUPLE PIECES OF ENERGY
THROUGH THE REST OF THE EXTENDED PERIOD. THE FIRST WAVE WILL
MOVE INTO THE NORTHERN PLAINS ON WEDNESDAY AND THEN SHIFT NORTHEAST
ACROSS THE MINNESOTA ARROWHEAD THURSDAY EVENING AND INTO ONTARIO ON
FRIDAY. THERE ARE STILL SOME MODEL DIFFERENCES WITH HOW PROGRESSIVE
THIS SHORTWAVE AND ASSOCIATED WEAK LOW (AND WARM FRONT) ARE...AND IT
IS LARGELY TIED INTO THE STRENGTH OF THE SHORTWAVE. AT THIS
POINT...THE 12Z GFS APPEARS TO BE THE OUTLIER (KEEPS THE WARM FRONT
SOUTH OF THE CWA DUE TO WEAKER SHORTWAVE UNTIL THE NEXT WAVE
ARRIVES ON SATURDAY) WHILE THE 00Z ECMWF AND ITS ENSEMBLE
MEMBERS...ALONG WITH THE 12Z GEM/NAM...BRING THE WARM FRONT INTO THE
AREA LATE THURSDAY AFTERNOON AND PUSHING NORTHEAST OF THE AREA ON
FRIDAY NIGHT INTO SATURDAY. THINK THE NON GFS CONSENSUS IS THE WAY
TO GO AT THIS POINT AND FOLLOWS THE GENERAL IDEA FROM THE PREVIOUS
SHIFT. THEREFORE...WILL INCREASE PRECIP CHANCES FROM SOUTHWEST TO
NORTHEAST THURSDAY AFTERNOON INTO THURSDAY NIGHT AND THEN KEEP
CHANCE POPS INTO THE FIRST PART OF THE WEEKEND. WILL NEED TO KEEP
AN EYE ON CONVECTION FIRING IN EAST CENTRAL MINNESOTA AND NORTHWEST
WISCONSIN THURSDAY AFTERNOON ALONG THE WARM FRONT AND LOW LEVEL
MOISTURE TRANSPORT MAXIMUM IS LOCATED. COULD SEE SOME STRONG TO
POTENTIAL SEVERE STORMS IN THAT AREA...WHICH BASED OFF STORM MOTION
VECTORS WOULD TRY TO LIFT THEM EAST-NORTHEAST ALONG WITH THE FRONT
WHILE BUILDING TO THE SOUTHEAST. FAR WESTERN UPPER MICHIGAN WOULD
HAVE THE BEST OPPORTUNITY FOR SEEING THESE STRONGER STORMS HEADING
INTO THE EVENING HOURS.
ONCE THAT WAVE DECAYS AND SLIDES NORTHEAST OF THE
CWA...PRECIPITATION CHANCES WILL DEPEND ON OTHER WAVES EJECTING OUT
OF THE UPPER TROUGH OVER THE NORTHERN ROCKIES. RIDGE AXIS WILL BE
RIGHT OVER THE U.P. THROUGH SUNDAY AND THEN SHIFT EAST FOR THE
BEGINNING OF NEXT WEEK AS THE UPPER TROUGH GRADUALLY SHIFTS EAST.
WITH THAT RIDGE AXIS...IT APPEARS THAT SUNDAY WILL BE THE BEST
OPPORTUNITY FOR DRIER WEATHER BEFORE THE NEXT WAVE SLIDES NORTHEAST
OVER THE WESTERN HALF OF THE CWA SUNDAY NIGHT INTO MONDAY MORNING.
EXPECT IT TO BE FAIRLY MUGGY OVER THE AREA FRIDAY INTO THE
WEEKEND....ESPECIALLY WHEN COMPARED TO WHAT HAS BEEN SEEN IN THIS
REGION FOR MUCH OF THE SUMMER. AFTER THE NORMAL TO SLIGHTLY ABOVE
NORMAL TEMPERATURES VALUES THURSDAY THROUGH SUNDAY...THEY ARE
EXPECTED TO FALL BACK BELOW NORMAL FOR MONDAY AND TUESDAY BEHIND THE
COLD FRONT ASSOCIATED WITH THE WAVE THAT MOVES THROUGH ON SUNDAY
NIGHT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 133 AM EDT WED AUG 20 2014
LOW PRES SYSTEM OVER THE UPPER GREAT LAKES WILL VERY SLOWLY DRIFT
ESE OVER THE NEXT 24HRS. ABUNDANT LOW-LEVEL MOISTURE ASSOCIATED WITH
SYSTEM WILL RESULT IN LIFR TO POSSIBLY OCNL VLIFR CONDITIONS AT
KIWD/KCMX/KSAW THRU AT LEAST MID MORNING. -SHRA/-DZ MAY ALSO OCCUR
AT TIMES...ESPECIALLY AT KCMX. GRADUAL IMPROVEMENT SHOULD OCCUR THIS
AFTN...THOUGH ONLY KIWD SHOULD REACH VFR BY THE LATTER PART OF THE
AFTN. KCMX/KSAW MAY NOT GET ABOVE THE LOW MVFR RANGE. AFTER
SUNSET...CONDITIONS MAY AGAIN FALL AT KCMX/KSAW...BUT ESPECIALLY AT
KSAW WHICH WILL BE CLOSER TO DEPARTING SYSTEM.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 422 PM EDT TUE AUG 19 2014
SOME FOG IS EXPECTED TO PERSIST OVER THE CNTRL AND ERN LAKE TONIGHT
GIVEN ABUNDANT LOW LEVEL MOISTURE AND LIGHT WINDS. EXPECT WINDS
UNDER 20 KTS THROUGH SATURDAY AS A RELATIVELY WEAK PRESSURE GRADIENT
DOMINATES THE UPPER GREAT LAKES ABOVE THE RELATIVELY COLD WATERS OF
LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...ROLFSON
MARINE...JLB
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
325 AM CDT WED AUG 20 2014
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 323 AM CDT WED AUG 20 2014
MESO ANALYSIS THIS MORNING INDICATING HIGH DEGREE OF
MOISTURE/INSTABILITY IN PLACE OVER THE REGION WITH PWS OVER 1.5"
AND MUCAPES AROUND 2000 J/KG. MEANWHILE INTENSE LLVL MOISTURE ADV
WAS FEEDING CONVECTIVE ACTIVITY WHICH HAS BLOSSOMED OVER CNTRL NEB
AND CNTRL SD ALONG AXIS OF DEEP LYR MOIST CONVERGENCE/BNDRY LYR
THETA-E ADV/315K ISENTROPIC UPGLIDE.
LAST SEVERAL RUNS OF HIRES HRRR SUGGESTING LINE OF CONVECTION
ORIENTED NW-SE WILL FIRE OVER THE CWA SOMETIME TWD SUNRISE THIS
MORNING. HRRR THEN LIFTS ACTIVITY NEWD TWD THE UPPER MIDWEST AND OUT
OF THE CWA BY 18Z THIS AFTN.
HEADING INTO THIS WEEKEND...GOOD MODEL AGREEMENT HIGH PRESSURE DOME
WILL BUILD OVER THE SERN STATES WILL ACT AS A BLOCK RESULTING IN
UPSTREAM AMPLIFICATION OF UPPER TROF OVER THE WRN CONUS. IN
ADDITION...BULK OF PCPN ACTIVITY IS PROGGED TO BE NOCTURNAL IN
NATURE THE REST OF THIS WEEK WITH BULK OF RAINFALL FOUND MAINLY
NORTH OF THE CWA. HOWEVER...QUITE PROBABLE THE CWA WILL SEE ITS
FAIR SHARE OF MUCH NEEDED PCPN THE NEXT SEVERAL DAYS.
TONIGHT...EXPECT CONVECTION TO FIRE FROM ERN SD TO SW NEB ALONG
INSTABILITY AXIS WHERE BNDRY LYR THETA-E CONVG WILL BE MOST
PREVALENT. ACTIVITY PROGGED TO EVENTUALLY ORGANIZE INTO A COMPLEX
AND SLOWLY MIGRATE EWD OVER ERN SD OVERNIGHT. IS LIKELY THAT SRN
PORTION OF MCS WILL PUSH DEEP INTO THE CWA...THUS FEEL COMPELLED
PUSH POPS INTO THE LIKELY CAT DURING THE OVERNIGHT TONIGHT.
THURSDAY NIGHT CONVECTION NOT LOOKING ALL THAT IMPRESSIVE AT THIS
POINT AND ANY ACTIVITY THAT DOES DEVELOP WILL BE LIGHTLY SCATTERED
IN NATURE AT BEST. THEREFORE TOKEN LOW POPS SEEM TO BE THE BEST FIT
FOR NOW. FRIDAY NIGHT THOUGH LOOKING RATHER PROMISING FOR GENEROUS
RAINFALL ASSOCIATED WITH ANTICIPATED NIGHTTIME COMPLEX. ENVIRONMENT
AT THAT TIME WILL BE PRIME WITH WARM CLOUD DEPTH OF 4K METERS...PWS
MORE THAN 2"...KI AOA 40...LLVL JET MOISTURE TRANSPORT FEED. MOST
LIKELY THAT HEAVIER RAINFALL AMOUNTS WILL BE FOUND OVER THE NRN
CWA...THUS WILL MENTION IN ZFP.
.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 323 AM CDT WED AUG 20 2014
FEATURE OF INTEREST STILL IS UPPER TROF OVER WRN CONUS RESPONSE TO
BLOCKING HIGH PRESSURE DOME OVER THE SERN CONUS WITH RATHER COOL
CANADIAN AIRMASS SWEEPING INTO THE NRN/CNTRL PLAINS EARLY NEXT WEEK.
GOING FCST WITH MAX TEMPS GENERALLY IN THE MID/UPPER 70S
MON/TUES/WED STILL LOOK REASONABLE FOR NOW. PCPN CHANCES IN THE EXT
PDS REMAINS CENTERED AROUND VERY SLOW MOVING COLD FRONTAL LEADING
THE CANADIAN AIR MASS INTO THE REGION FOLLOWED BY POST FRONTAL PCPN
ASSOCIATED WITH APPROACHING UPPER TROF. WITH ECM/GFS QPF IN RATHER
GOOD AGREEMENT...HAVE DECIDED TO BUMP POPS UP MON-WED PDS.
&&
.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1131 PM CDT TUE AUG 19 2014
VFR CONDITIONS WILL PREVAIL THROUGH MUCH OF THE TAF PERIOD.
HIGH BASED CONVECTION IS EXPECTED TO DEVELOP IN A NW-SE ARC ACROSS
THE AREA THROUGH THE OVERNIGHT PERIOD. A FEW MVFR CONDITIONS ARE
POSSIBLE DURING THIS TIME PERIOD AND HAVE CONTINUED A TEMPO GROUP
FOR THIS AT BOTH KOFK AND KOMA. KLNK SHOULD STAY OUT OF THE TSTMS.
SOUTHEASTERLY WINDS WILL INCREASE WEDNESDAY AFTERNOON WITH GUSTS
TO NEAR 25KTS BEHIND A WARM FRONT PUSHING NORTH INTO SD.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...DEE
LONG TERM...DEE
AVIATION...KERN
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
102 AM CDT WED AUG 20 2014
.UPDATE...
ISSUED AT 521 PM CDT TUE AUG 19 2014
UPDATED TO INCLUDE A SLIGHT CHANCE FOR THUNDERSTORMS FROM SWRN
NEBR INTO CENTRAL NEBRASKA AS THIS EVENING PROGRESSES. LATEST
REGIONAL RADAR MOSAIC SHOWS SCATTERED THUNDERSTORMS FROM NEAR
SCOTTSBLUFF THROUGH FORT MORGAN AND LAST CHANCE COLORADO. THE
LATEST HRRR AND RAP13 INDICATE THIS TO PUSH NORTHEAST AND INCREASE
IN COVERAGE INTO WRN NEBR THIS EVENING. RECENT ISOLATED
DEVELOPMENT NOW IN SHERIDAN AND CHERRY COUNTY ATTM.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 337 PM CDT TUE AUG 19 2014
SHORTWAVE RIDGING ALOFT CURRENTLY RESIDES OVER THE AREA...WITH VERY
LITTLE IN THE WAY OF CLOUD COVER EXCEPT FOR SOME HIGH CIRRUS CLOUDS.
SHORT TERM HRRR MODEL SUGGESTS THUNDERSTORMS WILL DEVELOP OVER THE
HIGHER TERRAIN TO THE WEST LATE THIS AFTERNOON...AND THEN DRIFT EAST
INTO WESTERN NEBRASKA THIS EVENING. LATEST VISIBLE SATELLITE TRENDS
CONFIRMS THIS THINKING...WITH QUITE A BIT IN THE WAY OF TOWERING
CUMULUS FROM CHEYENNE DOWN THROUGH THE DENVER METRO. SOUTHERLY LOW
LEVEL JET WILL INCREASE TO AROUND 35 KTS THIS EVENING...WHICH MAY
HELP SUPPORT STORMS AS THEY TRACK EAST. NOT EXPECTING COVERAGE TO BE
WIDESPREAD...AND DUE TO THE RIDGING ALOFT...NOT REAL CONFIDENT ON
HOW FAR EAST STORMS WILL MAKE IT. LATER TONIGHT...DECENT MID LEVEL
INSTABILITY DEVELOPS ACROSS NORTH CENTRAL INTO NORTHEAST
NEBRASKA...AND EXPECT AT LEAST SCATTERED COVERAGE OF ELEVATED
THUNDERSTORMS TO DEVELOP WITHIN AREA OF ISENTROPIC ASCENT.
A SURFACE TROUGH WILL EXTEND FROM NORTHEAST TO SOUTHWEST WEDNESDAY
AFTERNOON...AND SHOULD BE THE FOCUS FOR SCATTERED LATE AFTERNOON
THUNDERSTORMS. THE NAM MODEL IS THE FARTHEST EAST WITH THE
TROUGH...WHILE THE NMM...ARW AND GEM REGIONAL HOLD THE TROUGH BACK
FROM ROUGHLY AINSWORTH TO IMPERIAL. DECENT INSTABILITY DEVELOPS BY
AFTERNOON ALONG AND EAST OF THE TROUGH...WITH SURFACE BASED CAPES
APPROACHING 4000 J/KG. A BELT OF STRONGER MID LEVEL WINDS WILL ALSO
BE PRESENT BY AFTERNOON ON THE SOUTHERN FLANK OF A SHORTWAVE
CROSSING THE NORTHERN PLAINS. THE SYNOPTIC SET UP APPEARS SIMILAR TO
THE SUNDAY SEVERE EVENT...AND AGREE WITH THE STORM PREDICTION CENTER
SLIGHT RISK FOR SEVERE STORMS EAST OF HIGHWAY 83.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 337 PM CDT TUE AUG 19 2014
THE WEAK FRONT WILL CROSS CENTRAL NEBRASKA WEDNESDAY NIGHT AND
GENERATE A BAND OF THUNDERSTORMS...ESPECIALLY IN CENTRAL AND NORTH
CENTRAL NEBRASKA. MODEL OUTPUT STATISTICS INDICATE PROBABILITY/
COVERAGE OF 20-30 PERCENT IN THE SANDHILLS AND 30-40 PERCENT IN
CENTRAL AND NORTH CENTRAL NEBRASKA. THAT SEEMS REASONABLE. SURFACE
BASED CAPE IN CENTRAL AND NORTH CENTRAL NEBRASKA IS PRETTY HIGH AT
3500-4000J/KG WITH BULK SHEAR (0-6KM) AROUND 30KT. WITH STORM MOTION
240-260 AT 15-25KT...STORM RELATIVE HELICITY IS EXPECTED TO BE
110-200. SEVERE STORMS ARE POSSIBLE INTO THE EVENING...THOUGH WE
WILL NOT INCLUDE THE MENTION IN THE FORECAST FOR WEDNESDAY NIGHT.
A BOUNDARY LIFTING NORTH INTO SOUTHERN NEBRASKA WILL BRING THE
POSSIBILITY OF THUNDERSTORMS TO SOUTH CENTRAL AND SOUTHWEST NEBRASKA
THURSDAY NIGHT. AS THE BOUNDARY MAKES ITS WAY A LITTLE FARTHER NORTH
FRIDAY...THERE IS A POSSIBILITY OF THUNDERSTORMS IN CENTRAL AND
NORTHERN NEBRASKA.
FINALLY...SATURDAY NIGHT AND SUNDAY...A COOL FRONT COMES ACROSS
NEBRASKA AND THE PATTERN IS NOT AS FAVORABLE FOR STRONG CONVECTION.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 102 AM CDT WED AUG 20 2014
AN AREA OF LIGHT SHOWERS WITH A FEW EMBEDDED THUNDERSTORMS WILL MOVE
NORTHEAST ACROSS SOUTHWEST INTO EASTERN PORTIONS OF NORTH CENTRAL
NEBRASKA OVERNIGHT. FOR WEDNESDAY...A CHANCE FOR THUNDERSTORMS AT
KLBF AFTER 23Z/21ST AND INCLUDED IN A PROB30 FOR 5SM TSRA BKN070CB.
EXPECT TSRA TO DEVELOP AND REMAIN EAST OF KVTN TERMINAL AND DID NOT
INCLUDE THIS TAF ISSUANCE.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...ROBERG
SHORT TERM...TAYLOR
LONG TERM...SPRINGER
AVIATION...POWER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
909 PM PDT TUE AUG 19 2014
.SYNOPSIS...A LOW PRESSURE SYSTEM DROPPING DOWN THE WEST COAST WILL
ACT UPON MONSOON MOISTURE IN PLACE LEADING TO A CHANCE OF
THUNDERSTORMS OVER SOUTHEAST CALIFORNIA...SOUTHERN NEVADA AND
NORTHWEST ARIZONA AT LEAST THROUGH WEDNESDAY. TEMPERATURES WILL
REMAIN SEVERAL DEGREES BELOW NORMAL.
&&
.UPDATE...
OTHER THAN ADJUSTMENTS MADE DURING THE PREVIOUS UPDATE...NO OTHER
CHANGES ARE NEEDED AT THIS TIME. STILL HAVE THE STORMS PROPAGATING
SOUTHEAST THROUGH NORTHEASTERN LINCOLN COUNTY...HEADING FOR
SOUTHWEST UTAH. SHOWERS THAT WERE NEAR NIPTON AND SEARCHLIGHT HAVE
MOVED NORTH AND DISSIPATED AROUND JEAN. WE CONTINUE TO SEE A FEW
ISOLATED SHOWERS DEVELOPING NEAR BAKER...ASSOCIATED WITH SOME UPPER
LEVEL FORCING AND REMNANT INSTABILITY. THESE SEEM TO LAST ONLY ABOUT
45 MINUTES. WITH SURFACE DEWPOINTS IN THE 30S UNDER THOSE
SHOWERS...NOT SURE MUCH IS REACHING THE GROUND. THE LATEST HRRR /02Z
RUN/ DOES SHOW THESE SHOWERS BUT DISSIPATES THEM RATHER
QUICKLY...WILL CONTINUE TO MONITOR.
&&
.PREVIOUS UPDATE...
550 PM PDT TUE AUG 19 2014
DID A QUICK UPDATE TO EXTEND POPS WEST INTO EASTERN SAN BERNARDINO
AND SOUTHERN CLARK FOR A FEW MORE HOURS THAN PREVIOUSLY
FORECAST...WHERE CONVECTION IS ONGOING. ALSO UPDATED TO INCREASE
POPS FARTHER WEST IN LINCOLN COUNTY WHERE AN OUTFLOW BOUNDARY IS
PROPAGATING FROM THE NORTH TOWARD THAT AREA. NEW CONVECTION HAS
DEVELOPED ON THAT BOUNDARY AND...WITH DEWPOINTS STILL ELEVATED
ACROSS NORTHWEST LINCOLN COUNTY...EXPECT A FEW MORE THUNDERSTORMS TO
DEVELOP. THE LATEST HRRR /22Z RUN/ DOES INDICATE SOME CONVECTION
WILL DEVELOP ACROSS NORTHERN LINCOLN AND TRACK SOUTHEAST INTO UTAH.
WILL KEEP AN EYE ON THIS AREA AS WELL AS THE ONGOING CONVECTION FROM
NIPTON TO SEARCHLIGHT TO LAUGHLIN.
&&
.PREVIOUS DISCUSSION...
217 PM PDT TUE AUG 19 2014
.SHORT TERM...THROUGH WEDNESDAY NIGHT...BUSY AFTERNOON. EARLY
MORNING THUNDERSTORMS WORKED OVER LINCOLN AND EASTERN MOHAVE
COUNTIES...DRY AIR PUNCHING IN FROM THE WEST HAS CLEARED OUT MOST OF
SAN BERNARDINO COUNTY...AND THE NARROW WEDGE IN BETWEEN OVER FAR
EASTERN SAN BERNARDINO...SOUTHERN CLARK AND WESTERN MOHAVE HAS LIT
UP WITH BIG STORMS THIS AFTERNOON. AS THE MAIN LOW OVER THE WEST
COAST DIGS FARTHER SOUTH WEDNESDAY...SOUTHWEST FLOW OVER OUR AREA
WILL BACK AROUND TO THE SOUTH...ALLOWING THE MOISTURE TO SLOSH BACK
TO THE WEST AND BRING THUNDERSTORM CHANCES BACK TO AREAS SOUTHEAST
OF A LINE FROM BARSTOW TO HIKO. THE SIERRA NEVADA RANGE MAY ALSO SEE
A FEW STORMS THANKS TO THE INFLUENCE OF THE LOW. SOME STORMS ARE
LIKELY TO PERSIST THROUGH WEDNESDAY NIGHT OVER THE EASTERN CWA WITH
THE LOW NEARBY.
.LONG TERM...THURSDAY THROUGH TUESDAY...VERY LITTLE CHANGE TO THE
PREVIOUS THINKING. MODELS HAVE COME INTO SLIGHTLY BETTER AGREEMENT
BRINGING AN UPPER LEVEL LOW ACROSS THE AREA IN THE LATE WEDNESDAY
THROUGH THURSDAY TIMEFRAME. THURSDAY IS EXPECTED TO BE THE MOST
ACTIVE OF THE LONG TERM PERIOD WITH A GENERAL DRYING TREND
THEREAFTER. I DID EXPAND POPS A BIT FURTHER WEST ON THURSDAY TO
ACCOUNT FOR THE SLIGHTLY SLOW ECMWF AND NAM SOLUTIONS. BASICALLY
KEEPING POPS IN EAST OF A PIOCHE...MT. CHARLESTON...MORONGO VALLEY
LINE AND THE BEST CHANCES OVER MOHAVE COUNTY AND THE CLARK COUNTY
MOUNTAINS. KEPT IN A MENTION OF SHOWERS/THUNDERSTORMS OVER
SOUTHEASTERN MOHAVE COUNTY THURSDAY NIGHT AS ECMWF PUSHES THE LOW
OVER THE AREA.
FOR FRIDAY AND SATURDAY KEPT ONLY A SLIGHT CHANCE OF THUNDERSTORMS
MENTIONED OVER MOHAVE COUNTY TO ACCOUNT FOR ANY LINGERING MOISTURE.
OTHERWISE EXPECT DRIER CONDITIONS AND A WARMING TREND INTO EARLY
NEXT WEEK. THERE DOESN`T APPEAR TO BE A STRONG SIGNAL OF RETURNING
MOISTURE THROUGH THE BEGINNING OF NEXT WEEK.
&&
.AVIATION...FOR MCCARRAN...STRONG TO SEVERE THUNDERSTORMS WILL
AFFECT AREAS SOUTHEAST OF THE TERMINAL THIS EVENING AND
OVERNIGHT...WHICH COULD PRODUCE OUTFLOW WINDS AT THE TERMINAL AT
SOME POINT. THUNDERSTORM CHANCES WILL MOVE BACK INTO ALL APPROACH
CORRIDORS WEDNESDAY...WITH THE LOWEST CHANCE IN THE BEATTY CORRIDOR.
THERE WILL ALSO BE A SLIGHT CHANCE AT THE TERMINAL.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...STRONG TO SEVERE THUNDERSTORMS WILL AFFECT AREAS NEAR
AND EAST OF THE COLORADO RIVER THIS EVENING AND OVERNIGHT...WITH
EXTREMELY HEAVY RAINFALL AND HIGH WINDS THE MAIN THREATS.
THUNDERSTORM CHANCES WILL AFFECT AREAS ROUGHLY EAST OF A LINE FROM
BARSTOW TO HIKO ON WEDNESDAY.
&&
.SPOTTER INFORMATION STATEMENT...SPOTTERS SHOULD REPORT INSTANCES OF
FLASH FLOODING...STRONG GUSTY WINDS...HAIL...AND BLOWING DUST
THROUGH WEDNESDAY.
&&
$$
UPDATES...PADDOCK
SHORT TERM/AVIATION...MORGAN
LONG TERM...WOLCOTT
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS BISMARCK ND
122 AM CDT WED AUG 20 2014
.UPDATE...
ISSUED AT 103 AM CDT WED AUG 20 2014
THE MAIN FOCUS THIS MORNING IS ON PRECIPITATION AMOUNTS AND THE
FLOOD RISK. THE 00 UTC HIRES ARW AND WRF AND HRRR ARE IN GOOD
AGREEMENT THAT THE PREVIOUS FORECAST IS TOO FAST WITH THE ONSET OF
CONVECTION. THERE HAS ALSO BEEN A TREND TOWARD PUSHING CONVECTION
FURTHER NORTH...WHICH WOULD SPARE MUCH OF THE SOUTHWEST FROM
HEAVIER AMOUNTS. DECISIONS WILL NEED TO BE MADE THIS MORNING
REGARDING ANY FLOOD OR FLASH FLOOD WATCHES.
UPDATE ISSUED AT 953 PM CDT TUE AUG 19 2014
A FEW MINOR ADJUSTMENTS TO SKY COVER FOR THE LATE EVENING UPDATE.
LATEST RADAR IMAGERY SHOWS ISOLATED CONVECTION LIFTING THROUGH
SOUTH CENTRAL MONTANA...WHICH SHOULD MOVE INTO NORTH DAKOTA LATE
TONIGHT. THIS IS CURRENTLY HANDLED WELL. ALSO WEAK CONVECTION
CONTINUES TO FIRE OVER FAR NORTHEAST MONTANA INTO SOUTHERN
SASKATCHEWAN. MODELS DO SHOW AN INCREASING JET OVER WESTERN NORTH
DAKOTA TONIGHT IN AN AREA OF WEAK UPPER LEVEL DIVERGENCE AND
INSTABILITY ALOFT. COULD POSSIBLY BE SOME ELEVATED CONVECTION
ACROSS THE NORTHWEST INTO THE NORTH CENTRAL LATE TONIGHT SO
EXTENDED SOME SLIGHT POPS EAST ACROSS THESE AREAS AFTER MIDNIGHT.
UPDATE ISSUED AT 639 PM CDT TUE AUG 19 2014
A COUPLE OF THUNDERSTORMS DEVELOPED OVER SOUTHWEST NORTH DAKOTA
LATE THIS AFTERNOON IN AN AREA OF CAPES AROUND 2000 J/KG AND 25-35
KNOTS OF BULK SHEAR. ONE HAS DISSIPATED AS IT MOVED FROM BOWMAN
INTO ADAMS COUNTY. THE SECOND IS STILL HOLDING TOGETHER OVER
CENTRAL SLOPE. WILL MAINTAIN OUR SLIGHT CHANCE POPS OVER THE
SOUTHWEST. A FEW CELLS TRIED TO FIRE OVER THE NORTHWEST BUT WITH
LESS LUCK IN A LOW SHEAR ENVIRONMENT. SCATTERED CONVECTION OVER
NORTHEAST MONTANA CONTINUES TO LIFT NORTHEAST BUT IS HAVING A HARD
TIME MAINTAINING ITS STRENGTH AS IT APPROACHES NORTHWEST NORTH
DAKOTA. WILL HOLD OFF ON BRINGING ANY SLIGHT CHANCE POPS INTO THE
FAR NORTHWEST. OTHERWISE QUIET ACROSS MOST OF WESTERN AND CENTRAL
NORTH DAKOTA WITH NO CHANGES NEEDED TO THE GOING FORECAST.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 327 PM CDT TUE AUG 19 2014
THE MAIN CONCERN IN THE SHORT TERM FORECAST PERIOD IS EXPECTED
WIDESPREAD SHOWERS AND THUNDERSTORMS WEDNESDAY AND WEDNESDAY NIGHT.
THE PROBLEM IS LOW CONFIDENCE ON WHERE THE HEAVIEST RAINFALL TOTALS
CAN BE EXPECTED.
CURRENTLY...SURFACE LOW PRESSURE WAS OVER SOUTHWESTERN SASKATCHEWAN
AND NORTH CENTRAL MONTANA AHEAD OF AN UPPER LEVEL LOW/TROUGH OVER
UTAH. SURFACE DEWPOINTS WERE IN THE MID 50S WEST AND IN THE 60S OVER
EASTERN NORTH DAKOTA.
TONIGHT THE UPPER LOW LIFTS NORTHEASTWARD AND APPROACHES
SOUTHWESTERN NORTH DAKOTA. IN RESPONSE...THE SURFACE LOW/TROUGH
SHOULD DEVELOP EASTWARD SO THAT BY DAYBREAK WEDNESDAY IT IS ALONG
THE MONTANA/DAKOTAS BORDER. SOME MODELS ARE DEPICTING SOME ISOLATED
SHOWERS/THUNDER BEFORE DAYBREAK IN THE WEST...AND HAVE KEPT
ISOLATED/SMALL CHANCE PROBABILITIES FOR THE WESTERN QUARTER OF THE
STATE THROUGH DAYBREAK.
MODELS ARE IN GOOD AGREEMENT THAT SHORTLY AFTER/AT DAYBREAK THE
UPPER LEVEL ENERGY IMPULSES WILL BE SUFFICIENT FOR INCREASING
CHANCES OF SHOWERS AND THUNDERSTORMS THROUGH THE DAYLIGHT MORNING
HOURS. AROUND/AFTER NOON SHOWERS AND THUNDERSTORMS SHOULD BE
WIDESPREAD AND NUMEROUS ACROSS WESTERN AND CENTRAL NORTH DAKOTA.
WEDNESDAY EVENING MOST OF THE PRECIPITATION FROM THE THUNDERSTORMS
SHOULD BE IMPACTING ALL BUT THE FAR WESTERN PORTION OF NORTH
DAKOTA...WITH DECREASING CHANCES FROM WEST TO EAST LATE WEDNESDAY
NIGHT.
THE MAIN PROBLEM IS THAT THE VARIOUS MODELS ARE NOT COMING TO A GOOD
CONSENSUS REGARDING PLACEMENT OF THE HEAVIEST PRECIPITATION. THE NAM
MODEL IS FARTHEST NORTH WITH THE PLACEMENT OF HEAVY
PRECIPITATION...WITH WESTERN AND NORTH CENTRAL NORTH DAKOTA (SOURIS
RIVER BASIN) TAKING THE BIGGEST HIT. THE GFS/ECMWF WANT TO SPLIT THE
ENERGY - AND HENCE RESULTING IN TWO HEAVIER PRECIP BULLS-EYES - WITH
ONE OVER THE SOURIS BASIN...AND ANOTHER OVER CENTRAL NORTH DAKOTA.
THE OTHER SHORT TERM HIGH RESOLUTION MODELS ARE FAVORING SOUTH
CENTRAL NORTH DAKOTA.
FINAL PRECIPITATION FORECAST INVOLVES A SECTION OF SOUTH CENTRAL
NORTH DAKOTA INCLUDING THE JAMES RIVER VALLEY OF 1 TO 1.5 INCHES OF
RAIN...AND AROUND 0.75 TO 1 INCH OVER THE NORTHWEST/NORTH CENTRAL.
A HYDROLOGIC OUTLOOK (ESF) HAS BEEN ISSUED TO ADDRESS THIS FIRST
WAVE OF PRECIPITATION WEDNESDAY THROUGH WEDNESDAY NIGHT...THEN ALSO
ADDRESSES THE LONG TERM PERIOD EXPECTED PRECIPITATION THURSDAY NIGHT
THROUGH THE WEEKEND.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 327 PM CDT TUE AUG 19 2014
A VERY ACTIVE/WET PATTERN THROUGH THE WEEKEND WILL HIGHLIGHT THE
EXTENDED FORECAST PERIOD.
WILL NOTE 12Z MODELS STILL SHOW CONSIDERABLE SPREAD IN REGARDS TO
PRECIPITATION...TIMING/PLACEMENT/AMOUNTS...FRIDAY NIGHT THROUGH
SUNDAY. BETTER AGREEMENT THURSDAY THROUGH FRIDAY.
FOR THURSDAY...SHOWERS/THUNDERSTORMS WILL BE IN THE PROCESS OF
LIFTING OFF TO OUR NORTHEAST DURING THE MORNING AS A MID LEVEL S/WV
IMPULSE EJECTS INTO CANADA AND ITS ASSOCIATED SFC TROUGH PUSHES EAST
INTO THE UPPER MISSISSIPPI VALLEY. CONVECTIVE REDEVELOPMENT WILL BE
VERY POSSIBLE THURSDAY AFTERNOON/EVENING AS WE REMAIN IN
SOUTHWESTERLY FLOW ALOFT ALONG WITH AMPLE INSTABILITY AND DECREASING
CIN AS THE DAY PROGRESSES.
MAIN AREA OF PRECIPITATION WILL ENTER WESTERN NORTH DAKOTA THURSDAY
NIGHT AS ANOTHER EMBEDDED WAVE LIFTS NORTHEAST ACROSS EASTERN
MONTANA INTO FAR SOUTH CENTRAL CANADA...ALONG WITH FORCING
ASSOCIATED WITH THE UPPER LEVEL JET NOSING INTO THE REGION RESULTING
IN DIVERGENCE ALOFT OVERSPREADING THE NORTHERN PLAINS. BASED ON THE
PROJECTED TRACK OF THE MID LEVEL S/WV DEPICTED BY BOTH THE 12Z
GFS/ECMWF...MOST FAVORABLE AREAS FOR HEAVY PRECIPITATION WILL BE
OVER THE WESTERN HALF OF THE STATE AND INTO THE NORTH CENTRAL THURS
NIGHT-FRIDAY MORNING.
UPPER LEVEL TROUGH DIGS ACROSS THE WESTERN CONUS
FRIDAY-SATURDAY...THEN LIFTS NORTH AND EAST ACROSS THE DAKOTAS SAT
NIGHT-SUN NIGHT. MODEL SPREADS RATHER HIGH IN REGARDS TO
PRECIPITATION DURING THE FRIDAY/SATURDAY TIMEFRAME...WITH LEAD S/WV
IMPULSES DIFFICULT FOR MODELS TO KEY IN ON AT THIS TIME. SOME
LOCATION DIFFERENCES AS WELL SAT NIGHT INTO SUNDAY WITH THE TRACK OF
THE MAIN UPPER LEVEL WAVE WHEN IT MOVES ACROSS THE LOCAL REGION.
LOOKS TO BE WET MOST LOCATIONS.
WE REMAIN IN A QUASI-ACTIVE FLOW PATTERN INTO EARLY NEXT WEEK AS
WELL WITH A BROAD TROUGH IN PLACE ALOFT MONDAY AND TUESDAY.
TEMPERATURES WILL COOL SIGNIFICANTLY FROM FRIDAY INTO SUNDAY WITH
THE PRECIPITATION EXPECTED AND STRONG CAA ON SUNDAY IN THE WAKE OF A
STRONG SURFACE LOW AND UNDERNEATH THE UPPER WAVE. HIGHS SUNDAY WILL
BE IN THE 60S COMPARED TO UPPER 70S AND MID 80S ON THURSDAY. A
SLIGHT MODERATION IN HIGHS FORECAST NEXT WEEK MONDAY AND
TUESDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 103 AM CDT WED AUG 20 2014
THUNDERSTORMS WILL INCREASE FROM WEST TO EAST TODAY. THERE IS HIGH
UNCERTAINTY ON TIMING AND PLACEMENT BEYOND THAT TREND...SO THE
TIMING IN TAFS IS A BEST GUESS. THERE COULD BE MVFR VISIBILITIES
AND CEILINGS WITH STRONGER THUNDERSTORMS.
&&
.HYDROLOGY...
ISSUED AT 327 PM CDT TUE AUG 19 2014
THERE WILL BE POTENTIALLY SIGNIFICANT RAINS ACROSS MUCH OF WESTERN
AND CENTRAL NORTH DAKOTA FROM WEDNESDAY MORNING THROUGH EARLY
THURSDAY...AND THEN AGAIN THURSDAY NIGHT THROUGH SUNDAY. THOSE AREAS
OF THE STATE WHICH RECEIVE MULTIPLE PASSES OF HEAVY RAINS OF HEAVY
RAIN WILL LIKELY EXPERIENCE EXCESSIVE RUNOFF AND A HIGHER LIKELIHOOD
OF OVERLAND AND SMALL STREAM FLOODING.
WHILE THE SOURIS RIVER BASIN OF NORTH DAKOTA HAS BEEN RELATIVELY DRY
TO NEAR NORMAL THE PAST FEW WEEKS...SOME OF THE MODELS DEPICT
WIDESPREAD RAINS BETWEEN TWO AND FOUR INCHES ACROSS THE UPPER
PORTIONS OF THE SOURIS IN NORTH DAKOTA AND SASKATCHEWAN. AREAS THAT
RECEIVE AN INITIAL WETTING DURING THE EARLIER EVENT ARE MORE LIKELY
TO EXPERIENCE EXCESSIVE RUNOFF DURING THE LATTER RAINS. SEVERAL
MISSOURI RIVER TRIBUTARIES WERE PARTICULARLY HARD HIT BY HEAVY RAINS
LAST WEEKEND, INCLUDING THE KNIFE AND HEART RIVERS ALONG WITH APPLE
CREEK. THESE RIVERS WILL STILL BE RUNNING WELL ABOVE NORMAL AS THE
NEXT FEW WEATHER SYSTEMS MOVE INTO THE STATE.
THE JAMES AND PIPESTEM CREEK BASINS HAVE NOT BEEN PARTICULARLY
AFFECTED BY RECENT HEAVY RAINS. HOWEVER...THERE HAS BEEN ENOUGH RAIN
TO KEEP THE SOIL MOISTURE LEVELS AT OR ABOVE NORMAL FOR THIS TIME OF
YEAR.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SCHECK
SHORT TERM...JV
LONG TERM...NH
AVIATION...SCHECK
HYDROLOGY...AJS
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
224 AM EDT WED AUG 20 2014
.SYNOPSIS...
LOW PRESSURE OVER LAKE MICHIGAN WILL SLOWLY MOVE TO THE EASTERN
GREAT LAKES THROUGH THURSDAY...PUSHING A WEAK COLD FRONT SOUTH
ACROSS THE AREA. HIGH PRESSURE WILL BUILD OVER LAKE ERIE BEHIND THIS
SYSTEM THURSDAY NIGHT...SHIFTING TO THE EASTERN GREAT LAKES ON
FRIDAY. A WARM FRONT WILL LIFT NORTH ACROSS THE AREA ON FRIDAY AND
SATURDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
MAIN LINE OF SHOWERS AND THUNDERSTORMS MOVED EAST THROUGH THE AREA
WITH SOME POCKETS OF MORE ACTIVITY MOVING EAST INTO THE REGION AT
THIS TIME. ANOTHER LINE IS TRYING TO GET ORGANIZED OVER WESTERN
OHIO. POTENTIAL EXISTS THAT SOUTHERN PART OF THE LINE WILL TRY TO
FILL IN. NORTHERN PART IS NOT AS PROMISING. ALONG THIS LINE IS AN
AREA OF CONVERGENCE AND SOME INSTABILITY TO SUPPORT THE ACTIVITY AS
IT MOVES EAST. LATEST NAM OUTPUT SHOWS THIS AREA OF CONVERGENCE
MOVING HALFWAY EAST ACROSS THE FORECAST AREA BEFORE THE
CONVERGENCE WEAKENS WITH TIME. HOWEVER...LATEST HRRR MODEL DOES
SHOW THE WEAKENING A BIT ACROSS THE CENTRAL PORTIONS AND THEN NEW
DEVELOPMENT TAKES PLACE ALONG THE OUTFLOW BOUNDARY FURTHER EAST.
MINOR ADJUSTMENTS TO TEMPERATURES WITH THIS UPDATE.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/...
NEARLY VERTICALLY STACKED UPPER LEVEL AND SURFACE LOW WILL BE OVER
THE CENTRAL GREAT LAKES ON WEDNESDAY. A MOIST AND UNSTABLE AIR MASS
WILL RESIDE WITHIN THE AREA OF SOUTHERLY FLOW AHEAD OF THE SURFACE
LOW ACROSS MAINLY NE OHIO AND NW PA. CAPES ARE EXPECTED TO INCREASE
TO AROUND 2500 J/KG WITH SEVERAL MECHANISMS FOR CONVECTIVE INITIATION
DURING THE AFTERNOON. STORMS WILL FIRE DURING THE AFTERNOON AS THE
LOW SLOWLY MOVES EASTWARD. HIGHER RESOLUTION MODELS ALSO SHOW SOME
CONVERGENCE DOWNWIND OF LAKE ERIE THAT WILL SET UP SOUTH OF I-90.
LARGE SCALE FORCING WILL ALSO INCREASE DURING THE LATE AFTERNOON AS
A 35 KNOT MID-LEVEL JET STREAK MOVES THROUGH THE NORTHWESTERLY FLOW
ON THE BACK SIDE OF THE TROUGH. ALL OF THIS COMBINES TO MAKE
THUNDERSTORMS LIKELY ON THURSDAY ACROSS AT LEAST THE EASTERN HALF OF
THE FORECAST AREA. LESS CERTAIN IS IF ANYTHING CAN FIRE ACROSS NW
OHIO AHEAD OF THE JET STREAK WHICH CAN NOT BE ENTIRELY RULED OUT SO
WILL LEAVE A LOW POP IN THE NW OHIO. WHATEVER BREAKS EXIST IN THE
CLOUDS TO START THE DAY IN NE OHIO/NW PA WILL FILL IN QUICKLY AS
DIURNAL HEATING INCREASES...WHILE A GOOD DEAL OF SUN IS EXPECTED IN
THE DRIER AIR IN NW OHIO. HIGHS WILL RANGE FROM 77-85 AND WILL BE
HIGHEST IN THE WEST WHERE THEY WILL RECEIVE MORE SUN.
WEDNESDAY NIGHT WILL BE MOSTLY DRY AS WEAK COLD FRONT PUSHES SOUTH
WITH NEGATIVE THETA-E ADVECTION THROUGH THE COLUMN. WEAK HIGH
PRESSURE ALSO BUILDS IN BEHIND THE DEPARTING SURFACE LOW WHICH
SHOULD REDUCE CHANCES FOR PRECIPITATION DOWNWIND OF LAKE ERIE IN NE
OH/NW PA ON THURSDAY.
FARTHER SOUTH...SCATTERED THUNDERSTORMS ARE EXPECTED TO FIRE ALONG
STALLED BOUNDARY ON THURSDAY. THURSDAY NIGHT COULD ALSO BE ACTIVE
ACROSS THE SW HALF OF THE FORECAST AREA AS ENERGY MOVES AROUND THE
BUILDING RIDGE THURSDAY NIGHT. THIS WILL BE FOLLOWED BY A WARM FRONT
STARTING TO LIFT BACK NORTH ON FRIDAY. THIS WILL BE THE BEGINNING OF
THE WARMING TREND FOR THE WEEKEND...WITH HIGHS REACHING THE MID TO
UPPER 80S IN THE WEST ON FRIDAY.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
THE LONG TERM BEGINS ON SATURDAY WITH BOTH THE GFS AND ECMWF SHOWING
AN UPPER LEVEL HIGH CENTERED OVER THE SOUTHEASTERN STATES. A RIDGE
WILL EXTEND NORTH INTO THE CENTRAL LAKES. NOT MUCH CHANGES THROUGH
SUNDAY INTO MONDAY EXCEPT THAT LOW PRESSURE MOVING THROUGH SOUTHERN
CANADA WILL TILT THE AXIS OF THE RIDGE EAST A BIT HOWEVER IT SHOULD
STILL REMAIN WEST OF THE AREA. TUESDAY THE LOW MOVES TO NORTHERN
ONTARIO FLATTENING THE RIDGE ACROSS THE LAKES. GIVEN THE RIDGE
POSITION...WOULD EXPECT THAT ANY CONVECTION THAT GOES OVER THE TOP
OF THE RIDGE WILL DESCEND ON THE REGION FROM THE NORTH. FOR NOW
THOUGH IT WOULD BE FAIRLY DIFFICULT TO ANTICIPATE TIMING OTHER THAT
A SMALL CHANCE POP FOR AFTERNOON AND EARLY EVENING CONVECTION. WILL
HAVE A SLIGHT CHANCE POP IN FOR THE OVERNIGHT AND EARLY MORNING
PERIODS. ALSO...GUIDANCE SUGGESTS MORE CLOUD COVER THEN SEEMS
REASONABLE GIVEN THE RIDGE SO LOWERED CLOUD PERCENTAGES TO GET
PARTLY CLOUDY THROUGH MOST OF THE PERIOD. TEMPS AT OR ABOVE
NORMAL.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
CONVECTION CONTINUES TO DEVELOP OVER PORTIONS OF THE AREA AS LOW
PRESSURE DIGS INTO THE CENTRAL GREAT LAKES. AFTER THIS EARLY
MORNING CONVECTION IT APPEARS MOST OF THE THUNDERSTORMS WILL BE
NEAR AND EAST OF INTERSTATE 71. AREAS OF FOG WILL BE POSSIBLE
TOWARD SUNRISE WHERE THE RAIN HAS STOPPED.
WINDS WILL GENERALLY BE BELOW 12 KNOTS FROM THE SOUTH AND
SOUTHWEST. HOWEVER WESTERN AREAS MAY SEE WINDS AROUND TO THE WEST
IN THE WAKE OF A WEAK FRONT.
OUTLOOK...NON VFR POSSIBLE IN SHOWERS/THUNDERSTORMS THROUGH
FRIDAY.
&&
.MARINE...
LOW PRESSURE OVER THE GREAT LAKES WILL CONTINUE THROUGH TONIGHT AND
TUESDAY INTO MID WEEK...EVENTUALLY REACHING WESTERN NEW YORK BY
THURSDAY MORNING. FLOW AROUND THE LOW IS NOT PARTICULARLY STRONG SO
AM EXPECTING VARIABLE BUT GENERALLY LIGHT WINDS THROUGH THE PERIOD
RESULTING IN WAVES OF 2 FEET OR LESS ON THE LAKE.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KEC
NEAR TERM...LOMBARDY
SHORT TERM...KEC
LONG TERM...TK
AVIATION...MULLEN
MARINE...TK
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1223 AM EDT WED AUG 20 2014
.SYNOPSIS...
LOW PRESSURE OVER LAKE MICHIGAN WILL SLOWLY MOVE TO THE EASTERN
GREAT LAKES THROUGH THURSDAY...PUSHING A WEAK COLD FRONT SOUTH
ACROSS THE AREA. HIGH PRESSURE WILL BUILD OVER LAKE ERIE BEHIND THIS
SYSTEM THURSDAY NIGHT...SHIFTING TO THE EASTERN GREAT LAKES ON
FRIDAY. A WARM FRONT WILL LIFT NORTH ACROSS THE AREA ON FRIDAY AND
SATURDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
MAIN LINE OF SHOWERS AND THUNDERSTORMS MOVED EAST THROUGH THE AREA
WITH SOME POCKETS OF MORE ACTIVITY MOVING EAST INTO THE REGION AT
THIS TIME. ANOTHER LINE IS TRYING TO GET ORGANIZED OVER WESTERN
OHIO. POTENTIAL EXISTS THAT SOUTHERN PART OF THE LINE WILL TRY TO
FILL IN. NORTHERN PART IS NOT AS PROMISING. ALONG THIS LINE IS AN
AREA OF CONVERGENCE AND SOME INSTABILITY TO SUPPORT THE ACTIVITY AS
IT MOVES EAST. LATEST NAM OUTPUT SHOWS THIS AREA OF CONVERGENCE
MOVING HALFWAY EAST ACROSS THE FORECAST AREA BEFORE THE
CONVERGENCE WEAKENS WITH TIME. HOWEVER...LATEST HRRR MODEL DOES
SHOW THE WEAKENING A BIT ACROSS THE CENTRAL PORTIONS AND THEN NEW
DEVELOPMENT TAKES PLACE ALONG THE OUTFLOW BOUNDARY FURTHER EAST.
MINOR ADJUSTMENTS TO TEMPERATURES WITH THIS UPDATE.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/...
NEARLY VERTICALLY STACKED UPPER LEVEL AND SURFACE LOW WILL BE OVER
THE CENTRAL GREAT LAKES ON WEDNESDAY. A MOIST AND UNSTABLE AIR MASS
WILL RESIDE WITHIN THE AREA OF SOUTHERLY FLOW AHEAD OF THE SURFACE
LOW ACROSS MAINLY NE OHIO AND NW PA. CAPES ARE EXPECTED TO INCREASE
TO AROUND 2500 J/KG WITH SEVERAL MECHANISMS FOR CONVECTIVE INITIATION
DURING THE AFTERNOON. STORMS WILL FIRE DURING THE AFTERNOON AS THE
LOW SLOWLY MOVES EASTWARD. HIGHER RESOLUTION MODELS ALSO SHOW SOME
CONVERGENCE DOWNWIND OF LAKE ERIE THAT WILL SET UP SOUTH OF I-90.
LARGE SCALE FORCING WILL ALSO INCREASE DURING THE LATE AFTERNOON AS
A 35 KNOT MID-LEVEL JET STREAK MOVES THROUGH THE NORTHWESTERLY FLOW
ON THE BACK SIDE OF THE TROUGH. ALL OF THIS COMBINES TO MAKE
THUNDERSTORMS LIKELY ON THURSDAY ACROSS AT LEAST THE EASTERN HALF OF
THE FORECAST AREA. LESS CERTAIN IS IF ANYTHING CAN FIRE ACROSS NW
OHIO AHEAD OF THE JET STREAK WHICH CAN NOT BE ENTIRELY RULED OUT SO
WILL LEAVE A LOW POP IN THE NW OHIO. WHATEVER BREAKS EXIST IN THE
CLOUDS TO START THE DAY IN NE OHIO/NW PA WILL FILL IN QUICKLY AS
DIURNAL HEATING INCREASES...WHILE A GOOD DEAL OF SUN IS EXPECTED IN
THE DRIER AIR IN NW OHIO. HIGHS WILL RANGE FROM 77-85 AND WILL BE
HIGHEST IN THE WEST WHERE THEY WILL RECEIVE MORE SUN.
WEDNESDAY NIGHT WILL BE MOSTLY DRY AS WEAK COLD FRONT PUSHES SOUTH
WITH NEGATIVE THETA-E ADVECTION THROUGH THE COLUMN. WEAK HIGH
PRESSURE ALSO BUILDS IN BEHIND THE DEPARTING SURFACE LOW WHICH
SHOULD REDUCE CHANCES FOR PRECIPITATION DOWNWIND OF LAKE ERIE IN NE
OH/NW PA ON THURSDAY.
FARTHER SOUTH...SCATTERED THUNDERSTORMS ARE EXPECTED TO FIRE ALONG
STALLED BOUNDARY ON THURSDAY. THURSDAY NIGHT COULD ALSO BE ACTIVE
ACROSS THE SW HALF OF THE FORECAST AREA AS ENERGY MOVES AROUND THE
BUILDING RIDGE THURSDAY NIGHT. THIS WILL BE FOLLOWED BY A WARM FRONT
STARTING TO LIFT BACK NORTH ON FRIDAY. THIS WILL BE THE BEGINNING OF
THE WARMING TREND FOR THE WEEKEND...WITH HIGHS REACHING THE MID TO
UPPER 80S IN THE WEST ON FRIDAY.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
THE LONG TERM BEGINS ON SATURDAY WITH BOTH THE GFS AND ECMWF SHOWING
AN UPPER LEVEL HIGH CENTERED OVER THE SOUTHEASTERN STATES. A RIDGE
WILL EXTEND NORTH INTO THE CENTRAL LAKES. NOT MUCH CHANGES THROUGH
SUNDAY INTO MONDAY EXCEPT THAT LOW PRESSURE MOVING THROUGH SOUTHERN
CANADA WILL TILT THE AXIS OF THE RIDGE EAST A BIT HOWEVER IT SHOULD
STILL REMAIN WEST OF THE AREA. TUESDAY THE LOW MOVES TO NORTHERN
ONTARIO FLATTENING THE RIDGE ACROSS THE LAKES. GIVEN THE RIDGE
POSITION...WOULD EXPECT THAT ANY CONVECTION THAT GOES OVER THE TOP
OF THE RIDGE WILL DESCEND ON THE REGION FROM THE NORTH. FOR NOW
THOUGH IT WOULD BE FAIRLY DIFFICULT TO ANTICIPATE TIMING OTHER THAT
A SMALL CHANCE POP FOR AFTERNOON AND EARLY EVENING CONVECTION. WILL
HAVE A SLIGHT CHANCE POP IN FOR THE OVERNIGHT AND EARLY MORNING
PERIODS. ALSO...GUIDANCE SUGGESTS MORE CLOUD COVER THEN SEEMS
REASONABLE GIVEN THE RIDGE SO LOWERED CLOUD PERCENTAGES TO GET
PARTLY CLOUDY THROUGH MOST OF THE PERIOD. TEMPS AT OR ABOVE
NORMAL.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
ONGOING CONVECTION WILL KEEP THINGS INTERESTING THIS EVENING. THE
WORST OF THE ACTIVITY REMAINS OVER LAKE ERIE BUT SCATTERED STORMS
ARE LIKELY THROUGH MIDNIGHT OR SO. WILL HAVE TO WATCH THE STORMS
APPROACHING KFDY TO MAKE SURE THEY DON`T BECOME SEVERE. OUTFLOW
FROM THE STORMS OVER THE LAKE WILL LIKELY IMPACT KCLE IN AN HOUR
OR SO AND COULD SEE SOME BRIEF GUSTS TO 30 KNOTS WITH ANY OF THE
STRONGER STORMS. WIDESPREAD MVFR FOG IS LIKELY AFTER MIDNIGHT WITH
PATCHY IFR AT THE USUAL INLAND SPOTS. THERE WILL LIKELY BE MORE
PRECIP IN THE EAST TOMORROW BUT WILL BROAD BRUSH IT FOR NOW. LIGHT
S TO SW FLOW WILL EVENTUALLY BECOME WESTERLY ON WEDNESDAY
AFTERNOON.
OUTLOOK...NON VFR POSSIBLE IN SHOWERS/THUNDERSTORMS THROUGH
FRIDAY.
&&
.MARINE...
LOW PRESSURE OVER THE GREAT LAKES WILL CONTINUE THROUGH TONIGHT AND
TUESDAY INTO MID WEEK...EVENTUALLY REACHING WESTERN NEW YORK BY
THURSDAY MORNING. FLOW AROUND THE LOW IS NOT PARTICULARLY STRONG SO
AM EXPECTING VARIABLE BUT GENERALLY LIGHT WINDS THROUGH THE PERIOD
RESULTING IN WAVES OF 2 FEET OR LESS ON THE LAKE.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KEC
NEAR TERM...LOMBARDY
SHORT TERM...KEC
LONG TERM...TK
AVIATION...KUBINA
MARINE...TK
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
500 AM CDT WED AUG 20 2014
.UPDATE...
12Z TAF DISCUSSION.
&&
.AVIATION...
PATCHY FOG WILL BRING BRIEF MVFR/IFR VIS TO CKV/CSV EARLY THIS
MORNING. OTHERWISE...SATELLITE IMAGERY SHOWS SCT CUMULUS THIS
MORNING WHICH WILL INCREASE IN COVERAGE BY AFTERNOON...WITH VCTS
AT CSV AFTER 18Z. HRRR MODEL RUNS ARE RATHER AGGRESSIVE WITH
PRECIP ACROSS THE MID STATE LATER TODAY...SO CANNOT COMPLETELY
RULED OUT A -SHRA/-TSRA AT CKV/BNA EITHER. LIGHT SOUTHWEST TO WEST
WINDS ARE ANTICIPATED TODAY WITH SPEEDS 5-10 KTS.
SHAMBURGER
&&
.PREV DISCUSSION... /ISSUED 244 AM CDT WED AUG 20 2014/
DISCUSSION...
..TEMPS TO HEAT UP OVER THE NEXT SEVERAL DAYS...
SHORT WAVE EVIDENT IN WIND FIELD AND SOMEWHAT IN VORTICITY PATTERN
WORKING THROUGH EASTERN KENTUCKY DOWN THROUGH EASTERN TENNESSEE
WITH SHOWERS AND A FEW THUNDERSTORMS ACROSS EASTERN KENTUCKY TRYING
TO EXTEND DOWN ALONG TENNESSEE/KENTUCKY BORDER EAST OF MY CWA.
NORTHWEST FLOW WILL CONTINUE DURING THE DAY AS WARM/HOT UPPER
LEVEL ANTICYCLONE BEGINS BUILDING IN THIS DIRECTION FROM SOUTHERN
PLAINS. MODELS ARE KEEPING SMALL POPS IN FOR TODAY ACROSS ALL OF
MIDDLE TENNESSEE WITH A LITTLE BETTER CHANCE OVER EASTERN AREAS
AND PLATEAU. HAVE LOW CONFIDENCE THAT WE ARE GOING TO SEE MUCH
MORE THAN ISOLATED CONVECTION TODAY INTO THIS EVENING BUT DID
INCLUDE A SMALL POP IN FORECAST FOR TODAY AND EVENING. AS UPPER
RIDGE APPROACHES SUBSIDENCE GETS UNDERWAY WITH GOOD ADIABATIC
COMPRESSION WHICH WILL ACT TO DRY OUT TROPOSPHERE OVER THE NEXT
SEVERAL DAYS WHICH MEANS LITTLE OR NO CHANCE FOR RAIN. ADIABATIC
COMPRESSION WILL ALSO HEAT TEMPS UP WELL INTO THE 90S LATTER PART
OF THIS WORK WEEK...OVER THE WEEKEND INTO THE FIRST OF NEXT WEEK.
CLIMATE...THE HOTTEST TEMPERATURE SO FAR THIS SUMMER IN NASHVILLE
HAS BEEN 97 DEGREES ON AUGUST 6TH. LAST SUMMER (2013) THE HOTTEST
TEMPERATURE WAS 97 DEGREES ON JULY 17TH.
HOTTEST SUMMER TEMPS SINCE 2000...
2013...97 JULY 17TH
2012...109 JUNE 29TH ALL-TIME RECORD HIGH FOR NASHVILLE
2011...102 AUGUST 3RD
2010...101 AUGUST 4TH
2009...95 JUNE 22ND AND JUNE 27TH
2008...97 JULY 21ST AND AUGUST 5TH
2007...106 AUGUST 16TH ALL-TIME RECORD HIGH FOR AUGUST
2006...100 JULY 19TH
2005...98 AUGUST 11TH...12TH AND 20TH
2004...94 JULY 13TH
2003...94 JULY 28TH
2002...97 AUGUST 5TH
2001...95 JULY 8TH
2000...100...AUGUST 17TH
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
55
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1151 PM CDT TUE AUG 19 2014
.SHORT TERM...(TONIGHT THROUGH WEDNESDAY NIGHT)
ISSUED AT 252 PM CDT TUE AUG 19 2014
WATER VAPOR IMAGERY COUPLED WITH RAP 500MB ANALYSIS SHOWING A MID-
LEVEL LOW OVER WESTERN UPPER MICHIGAN. COLD POOL ALOFT ASSOCIATED
WITH THE LOW PRODUCING WIDESPREAD CUMULUS/STRATOCUMULUS FIELD ACROSS
THE FORECAST AREA WITH RADAR EVEN SHOWING A FEW SHOWERS POPPING UP
ACROSS NORTHERN MN INTO NORTHERN WI. OTHERWISE...TEMPERATURE ACROSS
THE ARX FORECAST AREA WERE IN THE 70-80 DEGREE RANGE.
FOR TONIGHT...COULD SEE A FEW SHOWERS NORTHEAST OF I-94 THIS EVENING
BUT THEN EXPECTING CLOUDS TO DIMINISH LATE IN THE EVENING AND
THROUGH THE OVERNIGHT HOURS AS A RIDGE OF HIGH PRESSURE MOVES
OVERHEAD. THIS WILL SET UP FAVORABLE FOG POTENTIAL OVERNIGHT/EARLY
WEDNESDAY MORNING...ESPECIALLY FAVORED RIVER VALLEY LOCATIONS.
THINKING AREAS SOUTHWEST OF I-94 WILL BE MOST IMPACTED WHERE
CONFIDENCE IS HIGHER FOR CLEARING SKY CONDITIONS EXISTS. HELD OFF ON
DENSE FOG ADVISORY FOR NOW BASED ON INPUT FROM SURROUNDING
OFFICES...BUT EVENING FORECASTER WILL HAVE TO MONITOR CLOSELY FOR
POSSIBLE FOG HEADLINE. LOOK FOR LOWS TONIGHT IN THE MIDDLE 50S TO
THE LOWER 60S.
AFTER AREAS OF MORNING FOG...PLAN ON THE RIDGE OF HIGH PRESSURE TO
KEEP THE FORECAST AREA DRY THROUGH WEDNESDAY. AN APPROACHING WARM
FRONT FROM THE CENTRAL PLAINS/MID-MISSISSIPPI RIVER VALLEY WILL
LIKELY SPARK A FEW SHOWERS AND THUNDERSTORMS...BUT PRETTY CONFIDENT
THESE WILL REMAIN SOUTH OF THE AREA. OTHERWISE...EXPECTING HIGH
TEMPERATURES TO TOP OFF IN THE MID 70S TO THE LOWER 80S.
LOOK FOR SHOWERS AND THUNDERSTORMS TO BECOME LIKELY BY LATE
WEDNESDAY NIGHT AS THE WARM FRONT CONTINUES TO APPROACH THE REGION.
ALL MODELS SHOW 850MB MOISTURE TRANSPORT INCREASING INTO/OVER THE
FRONT...WITH BEST AXIS OF MOISTURE PLUME REMAINING JUST WEST OF THE
FORECAST AREA. IN FACT...THE GFS/NAM SHOWING PRECIPITABLE WATER
VALUES SURGING INTO THE 1.5-2 INCH RANGE. THIS COULD LEAD TO SOME
LOCALIZED HEAVIER RAINFALL AS WARM CLOUD LAYER DEPTH INCREASE TO
AROUND 4KM BY MORNING. MAY NEED TO MONITOR THE POTENTIAL FOR A FEW
SEVERE THUNDERSTORMS WITH LARGE HAIL INITIALLY WITH THE INCOMING
CONVECTION AS NAM INDICATING 1-6KM MUCAPE IN THE 2500-3500J/KG RANGE
COUPLED WITH 25-35KT BULK SHEAR.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 252 PM CDT TUE AUG 19 2014
MODELS SHOWING THE WARM FRONT PUSHING NORTHEAST THROUGH THE AREA ON
THURSDAY FOR THE CONTINUED LIKELIHOOD OF SHOWERS AND THUNDERSTORMS.
MODELS ALSO SHOWING 850MB MOISTURE TRANSPORT WANING THROUGH THE
MORNING HOURS AND EVENTUAL CAPPING ALONG AND WEST OF THE MISSISSIPPI
DURING THE AFTERNOON HOURS. AS SUCH...DIVIDED POPS INTO
MORNING/AFTERNOON TIME PERIODS. STILL LOOKING AT THE POTENTIAL FOR
SOME LOCALIZED HEAVY RAINFALL THROUGH THE MORNING HOURS WITH
PRECIPITABLE WATER VALUES LINGERING IN THE 1.5 TO 2 INCH RANGE.
OTHERWISE...LOOK FOR SUBSTANTIALLY MORE HUMID CONDITIONS AS DEW
POINTS CREEP UP INTO THE LOWER 70S. THESE DEW POINTS COMBINED WITH
DAYTIME HIGHS WELL INTO THE 80S FOR MOST OF THE AREA ARE EXPECTED
TO PRODUCE HEAT INDICES IN THE 90 TO 100 DEGREE...HIGHEST ALONG AND
WEST/SOUTH OF THE MISSISSIPPI/WISCONSIN RIVERS.
FOR THURSDAY NIGHT THROUGH THE REST OF THE PERIOD...FORECAST
CONFIDENCE WANES FAIRLY RAPIDLY. MODEL CONSENSUS SHOWS A MID-LEVEL
RIDGE TRYING TO ESTABLISH ITSELF OVER THE CENTRAL CONUS.
HOWEVER...MESSY FLOW WITH MONSOONAL TAP WILL BE IN PLACE ACROSS THE
INTERMOUNTAIN/PLAINS REGION. TIMING OF THESE WAVES PRETTY UNCERTAIN
AT THIS TIME. AS SUCH...WILL KEEP LOW-MEDIUM RANGE
SHOWER/THUNDERSTORM CHANCES IN THROUGH THE PERIOD. TEMPERATURES
THROUGH THE PERIOD LOOK TO STAY AT OR A FEW DEGREES ABOVE NORMAL
THROUGH THE WEEKEND...WITH PERHAPS SOME COOLING EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1151 PM CDT TUE AUG 19 2014
CONFIDENCE REMAINS FAIRLY HIGH THAT VALLEY FOG WILL DEVELOP
OVERNIGHT WITH THE MAIN CONCERN JUST BEING WITH SOME SCATTERED MID
LEVEL CLOUDS THAT HAVE BEEN DROPPING SOUTHEAST FROM
MINNESOTA/NORTHWEST WISCONSIN. OTHERWISE...DEW POINT SPREADS ARE
LOW...WINDS ARE CALM AT THE SURFACE AND LIGHT ON UP THROUGH THE
LOWEST 3KFT. THE MAIN QUESTION IS JUST WITH HOW FAST THE FOG WILL
FORM AND THEN DISSIPATE OVERNIGHT. ONSET STILL APPEARS TO BE
AROUND 9Z WITH DISSIPATION COMING AROUND 14-15Z BASED ON
CLIMATOLOGY. WITH THE RIDGE OVERHEAD...WINDS WILL REMAIN CALM WITH
SKIES CLEAR FOR MUCH OF THE DAY BEFORE SHOWERS AND THUNDERSTORMS
DEVELOP WEDNESDAY EVENING. THIS CONVECTION LOOKS LIKE IT WILL
DEVELOP ALONG A NORTHWEST TO SOUTHEAST BAND AND COULD BE HEAVY AT
TIMES...BRINGING VISIBILITY CONDITIONS TO IFR/MVFR.
&&
.HYDROLOGY...WEDNESDAY NIGHT INTO THURSDAY
ISSUED AT 252 PM CDT TUE AUG 19 2014
THERE IS THE LIKELIHOOD FOR SHOWERS AND THUNDERSTORMS WITH THE
POTENTIAL FOR HEAVY RAINFALL WEDNESDAY NIGHT INTO THURSDAY MORNING.
EXPECTING FAIRLY WIDESPREAD 1/4 TO 3/4 INCH RAINFALL WITH LOCALIZED
GREATER THAN 1 INCH AMOUNTS. THIS RAINFALL COMBINED WITH RECENT
POCKETS OF HEAVY RAINS ACROSS PORTIONS OF THE FORECAST AREA COULD
LEAD TO SOME LOCALIZED FLOODING CONCERNS. WILL KEEP A CLOSE EYE ON
LOCALIZED FLOODING CONCERN AND THE POTENTIAL FOR A FLASH FLOOD WATCH
HEADLINE WEDNESDAY NIGHT INTO THURSDAY MORNING ONCE CONFIDENCE
INCREASES ON EXACTLY WHERE THE HEAVIER RAINFALL WILL OCCUR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION...HALBACH
HYDROLOGY...DAS
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1216 AM MDT WED AUG 20 2014
.UPDATE...
ISSUED AT 958 PM MDT TUE AUG 19 2014
STRONG TO SEVERE THUNDERSTORM CHANCES HAVE ENDED FOR THE REST OF
TONIGHT. WILL MAINLY SEE SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THE REST OF TONIGHT.
&&
.SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)
ISSUED AT 250 PM MDT TUE AUG 19 2014
THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS WHERE THE
CONVECTION WILL BREAK OUT THIS AFTERNOON AND HOW MUCH CONVECTION
WILL BREAK OUT AHEAD OF THE JET STREAK MOVING ACROSS THE ROCKIES
TONIGHT.
LATEST VISIBLE IMAGERY WAS SHOWING SOME ACCAS DEVELOPING ACROSS NORTHEAST
COLORADO NEAR THE SURFACE TROF. THIS AREA MAY END UP BEING THE
FIRST AREA TO FIRE UP THIS AFTERNOON. HOWEVER...IT MAY TRY TO
IGNITE JUST EAST OF THE LARAMIE AND FRONT RANGES AS WELL WHERE WE
HAVE HAD QUITE A BIT OF SUNSHINE. IN FACT...WE ARE STARTING TO SEE
A LITTLE BIT OF ACCAS OVERHEAD AND CONVECTION DEVELOPING ALONG THE
FRONT RANGE. MODELS ARE PROJECTING MIXED LAYER CAPES TO APPROACH 1500
J/KG THIS AFTERNOON WITH VERY LIMITED CAP. 0-6KM SHEAR VALUES
(~30KTS) MAY ALSO BE FAVORABLE FOR A FEW STRONG TO SEVERE STORMS.
AT THIS POINT...IT LOOKS THE HRRR IS STARTING TO BREAK OUT
CONVECTION JUST EAST OF CHEYENNE AFTER 21Z WITH THE BULK OF THIS
CONVECTION PUSHING GENERALLY EAST AT AROUND 20KTS. A FEW OF THESE
STORMS MAY HAVE THE POTENTIAL TO PRODUCING STRONG WINDS AND HAIL IN THE
PANHANDLE THIS AFTERNOON. LATEST SURFACE ANALYSIS WAS ALSO SHOWING
SOME WINDS BACKING TO THE SOUTHEAST IN THE PANHANDLE. WE WILL ALSO
NEED TO WATCH THAT AS THE AFTERNOON WEARS ON...ESPECIALLY IF THE
STORMS GET GOING IN THAT REGION.
ANOTHER CONCERN IS THE NAM IS SHOWING A 500MB JET STREAK MOVING
OUT OF NORTHEAST COLORADO EARLY THIS EVENING WHICH MAY HELP
ENHANCE THE SHEAR ACROSS THE PANHANDLE. IF CONVECTION IS ON GOING
IN THAT REGION AS THIS JET STREAK MOVES ACROSS WE MAY HAVE MORE OF
A SEVERE POTENTIAL. THEREFORE...IT WILL BE A MATTER OF TIMING ON
HOW THINGS COME TOGETHER LATE THIS AFTERNOON AND EVENING.
TONIGHT THE MODELS ARE SHOWING A FAIRLY STRONG UPPER LEVEL JET
MOVING THROUGH NORTHERN COLORADO AND LIFTING NORTHEAST INTO
NORTHEAST WYOMING BY DAYBREAK WHICH WILL HELP ENHANCE UPPER LEVEL
DIFFLUENCE. THE MODELS ARE EVEN IN FAIRLY GOOD AGREEMENT IN
SHOWING A MID LEVEL CIRCULATION WITH THIS JET STREAK. AS A
RESULT... WE WOULD NOT SURPRISED TO SEE A COMPLEX OF SHOWERS AND
THUNDERSTORMS DEVELOP ACROSS THE WESTERN HALF OF THE FORECAST AREA
OVERNIGHT ALONG WITH THE POTENTIAL FOR HEAVY RAINFALL DUE TO PRECIPITABLE
WATER VALUES AROUND 1 INCH. NOT EXPECTING MUCH IN THE WAY OF
FLOODING SINCE THIS COMPLEX SHOULD BE FAIRLY PROGRESSIVE. WE DID
BUMP UP POPS ACROSS THE NORTHERN HALF OF THE AREA TONIGHT TO
REFLECT THIS POTENTIAL.
WEDNESDAY-THURSDAY NIGHT:
THE MID LEVEL CIRCULATION IS PROGGED TO CONTINUE LIFTING NORTHEAST
WHICH WILL TAKE THE BULK OF THE CONVECTION NORTHEAST OF THE
FORECAST AREA BY MID MORNING. THIS WILL LEAVE A FAIRLY BROAD AREA OF
SUBSIDENCE IN THE MORNING IN THE WAKE OF THE CONVECTION...BUT WE
MAY MORE CONVECTION DEVELOP IN THE AFTERNOON ACROSS THE MOUNTAINS
AS UPSLOPE FLOW COMMENCES WITH LEFTOVER RESIDUAL MOISTURE.
OTHERWISE...THE REMAINDER OF THE AREA EAST OF THE LARAMIE RANGE
SHOULD REMAIN FAIRLY DRY WITH HIGHS GENERALLY IN THE 80S. THE
NEXT CHANCE OF SHOWERS AND THUNDERSTORMS IS PROGGED TO TAKE PLACE
ON THURSDAY AFTERNOON AS ANOTHER UPPER LEVEL WAVE LIFTS NORTHEAST
OUT OF COLORADO AND PUSHES THROUGH AREAS EAST OF THE LARAMIE RANGE
THURSDAY AFTERNOON INTO THURSDAY NIGHT.
.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 250 PM MDT TUE AUG 19 2014
AN UPPER LOW AND ASSOCIATED TROUGH OVER THE PACIFIC NW FRIDAY WILL
MOVE SLOWLY EAST TOWARDS THE AREA FRIDAY THROUGH SATURDAY...
SWINGING BY THE AREA ON SUNDAY. THIS WILL COMBINE WITH AT LEAST
RESIDUAL MONSOONAL MOISTURE TO KEEP CHANCES FOR SHOWERS AND TSTMS
GOING OVER MOST AREAS THROUGH SATURDAY NIGHT. WILL CONTINUE TO
LEAN TOWARDS THE EC SOLUTION AS IT HAS BEEN FAIRLY CONSISTENT WITH
THIS FEATURE. WARM TEMPS WILL CONTINUE THROUGH SATURDAY THEN A
DECENT COOL FRONT WILL PASS ACROSS SAT NIGHT LEAVING A DRIER AND
MILD DAY FOR THE CWA SUNDAY. CONTINUED MILD ON MONDAY WITH THE CWA
ON THE SOUTHERN PORTION OF BROAD CYCLONIC UPPER FLOW THAT WILL BE
OVER THE NORTHERN PART OF THE COUNTRY. A SECOND UPPER SHORTWAVE
SHOULD PASS BY TUESDAY BRINGING A REINFORCING SHOT OF COOLER AIR
AND A CHANCE FOR SOME PRECIPITATION.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1215 AM MDT WED AUG 20 2014
SHOWERS WILL INCREASE FROM WEST TO EAST ACROSS THE AREA TONIGHT.
VFR CONDITIONS ARE EXPECTED FOR MOST TERMINALS WITH CIGS BETWEEN
5K AND 10K FEET AGL. BRIEF MVFR CIGS OR VSBYS COULD OCCUR WITH ANY
HEAVIER PRECIPITATION AFTER 06Z. ISOLATED SHOWERS OR WEAK TSTMS
COULD BE IN THE VICINITY OF MOST TERMINALS THROUGH MOST OF THE TAF
PERIOD. WINDS WILL GENERALLY BE BELOW 15 KTS...EXCEPT GUSTY AND
VARIABLE NEAR ANY SHOWERS.
&&
.FIRE WEATHER...
ISSUED AT 1056 AM MDT TUE AUG 19 2014
FIRE WEATHER CONCERNS TO REMAIN MINIMAL FOR THE REST OF THE WEEK
WITH NON-CRITICAL WEATHER CONDITIONS EXPECTED. SOME WETTING RAINS
SHOULD OCCUR OVER AT LEAST PARTS OF THE AREA OVER THE NEXT COUPLE
DAYS AS A SURGE OF MONSOONAL MOISTURE PASSES OVER THE REGION AND
INCREASES PRECIPITATION.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
UPDATE...SML
SHORT TERM...REC
LONG TERM...RE
AVIATION...HAMMER
FIRE WEATHER...RE
AREA FORECAST DISCUSSION
NWS MIAMI FL
1031 AM EDT WED AUG 20 2014
.UPDATE...
RIDGE OF HIGH PRESSURE STRETCHES ACROSS THE COUNTY WARNING AREA.
PRECIPITABLE WATER VALUES HAVE JUMPED UP TO NEAR NORMAL TODAY WITH
MAGNITUDE OF LOW TO MID LEVEL LAPSE RATES (-6.4 C/KM) AND H5 TEMPS
(-7.5 C) SLIGHTLY ABOVE NORMAL AND SFC BASED CAPE AROUND 4500
J/KG. STORM MOTION VECTOR FOR THE DAY IS FROM THE EAST AT LESS
THAN 3 KNOTS. BASICALLY STORMS WILL BE NEARLY STATIONARY WITH
DEVELOPMENT AND MOVEMENT LIKELY DOMINATED BY OUTFLOW BOUNDARY
INTERACTIONS. LIMITING FACTOR REMAINS UNIMPRESSIVE MID LEVEL LAPSE
RATES. ALL IN ALL, THERMODYNAMIC PROFILE FOR THE DAY INDICATE
POTENTIAL FOR WIND GUSTS IN EXCESS OF 40 MPH, FREQUENT LIGHTNING
STRIKES, AND LOCALLY HEAVY RAINFALL PARTICULARLY WITH INLAND
STORMS. SO WILL AMEND HWO ACCORDINGLY. ENSEMBLE OF HIGH RES MODELS
AND HRRR ALSO INDICATE THAT BEST CHANCES OF THUNDERSTORMS TODAY
REMAIN FOR THE INTERIOR SOUTH WITH HIGH CHANCES SPREADING TOWARDS
THE WEST COAST AND LOWER CHANCES SPREADING AS FAR EAST AS THE
WESTERN SUBURBS OF THE EAST COAST METRO AREAS PARTICULARLY
STARTING AROUND 2 PM AND INTO THE EARLY EVENING.
FORECAST HAS BEEN UPDATED ACCORDINGLY.
&&
.PREV DISCUSSION... /ISSUED 735 AM EDT WED AUG 20 2014/
AVIATION...
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE BULK OF THE
PERIOD AS HIGH PRESSURE REMAINS IN CONTROL. THE LATEST MODEL RUN
SHOWED ISLTD/SCT SHRAS/TSTMS DEVELOPING ALONG THE EAST COAST SEA
BREEZE BOUNDARY AROUND 16-17Z JUST INLAND OF THE EAST COAST TAF
SITES WITH THE LOW-LEVEL FLOW PROJECTED TO BE MORE ORIENTED OUT OF
THE ENE. WILL INCLUDE VCTS FOR THE EAST COAST SITES TO CORRESPOND
WITH THIS TIMING FOR NOW AND UPDATE AS CONDITIONS EVOLVE TODAY.
THIS ACTIVITY SHOULD CONTINUE INLAND THROUGH THE MID-LATE
AFTERNOON AND SETUP ACROSS THE INTERIOR AREAS THROUGH THE EARLY
EVENING HOURS BEFORE DIMINISHING TONIGHT. WINDS WILL BECOME CALM
AND SHIFT TO OFFSHORE ALONG EACH COAST THROUGH THE LATE NIGHT
HOURS. 85/AG
PREV DISCUSSION... /ISSUED 238 AM EDT WED AUG 20 2014/
DISCUSSION...
SOUTH FLORIDA IS UNDER AN AREA OF HIGH PRESSURE LOCATED OVER THE
FLORIDA STRAITS. THE FORECAST CALLS FOR THIS AREA OF HIGH PRESSURE
TO MOVE TO THE NORTHWEST INTO THE SOUTHEASTERN US. THE 00Z AUG 20
SOUNDING SHOWS THAT THE SAHARAN DUST THAT HAS BEEN AFFECTING SOUTH
FLORIDA SINCE THE WEEKEND IS ERODING BETWEEN 600 AND 700 MB (OR 3-4
KM ABOVE THE SURFACE). THIS IS ALSO DEPICTED BY THE LIDAR LOCATED
AT THE UNIVERSITY OF MIAMI. THE LIDAR ALSO SHOWS THAT THE SAHARAN
LAYER IS BEING ERODED FROM BELOW. AS THE HIGH PRESSURE CONTINUES
TO MOVE TO THE NORTHWEST, AN INFLUX OF ATLANTIC AIR ASSOCIATED
WITH A WEAK FRONTAL BOUNDARY OVER THE ATLANTIC (BACK DOOR COLD
FRONT) WILL CONTINUE TO PROVIDE A SOURCE OF CLEANER AIR. THE LOW
LEVEL VISIBILITY WILL CONTINUE TO IMPROVE AS THE WEEK PROGRESSES.
THE CIMMS WATER VAPOR IMAGERY SHOWS INCREASING MOISTURE OVER THE
BAHAMAS MOVING OVER SOUTH FLORIDA FOR WEDNESDAY EVENING BEHIND THE
DRIER AIR THAT HAS BEEN AFFECTING SOUTH FLORIDA SINCE SATURDAY. THE
FORECAST SOUNDINGS ALSO SHOW THIS INCREASE IN PW FOR WEDNESDAY
AFTERNOON. THE PW DECREASE AGAIN ON THURSDAY DUE TO THE
SUBSIDENCE ASSOCIATED WITH THE HIGH PRESSURE MOVING INTO THE SE
US.
THE FLOW OF EASTERLY WINDS WILL FAVOR LOWER POPS FOR THE IMMEDIATE EAST
COAST WITH THE BEST CHANCES FOR AFTERNOON AND EVENING THUNDERSTORMS
OVER THE INTERIOR AND WESTERN PORTIONS OF THE COASTAL COUNTIES.
THE WEEKEND SEEMS TO BE THE DRIEST PERIOD WITH DRIER AIR FROM THE
ATLANTIC AFFECTING SOUTH FLORIDA. CONDITIONS ARE FORECAST TO
CHANGE FOR MONDAY AND TUESDAY AS MOISTURE ASSOCIATED WITH THE
TROPICAL WAVES OVER THE CENTRAL ATLANTIC IS EXPECTED TO AFFECT
SOUTH FLORIDA. AT THE PRESENT TIME IT IS NOT POSSIBLE TO PREDICT IF
A TROPICAL SYSTEM COULD AFFECT SOUTH FLORIDA NEXT WEEK, BUT AT
LEAST WE CAN BE SOMEWHAT CONFIDENT THAT AN INCREASE IN MOISTURE
AND LOW LEVEL FLOW FROM THE SE IS FORECAST FOR THE BEGINNING OF
NEXT WEEK ASSOCIATED WITH THESE WAVES. THE CURRENT FORECAST FROM
THE NATIONAL HURRICANE CENTER INCLUDES A MEDIUM CHANCE FOR
DEVELOPMENT FOR THE NEXT FIVE DAYS.
MARINE... WINDS ARE FORECAST TO REMAIN SOUTHEASTERLY TO EASTERLY
ACROSS THE ATLANTIC WATERS AROUND OR BELOW 10 KNOTS AND PERSISTING
THROUGH WEDNESDAY. AS A RESULT, SEAS ARE FORECAST TO BE 2 FEET OR
LESS THROUGH THIS TIME FRAME. SURFACE WINDS ARE THEN FORECAST TO
INCREASE SLIGHTLY FOR THE LATTER HALF OF THE WEEK WHILE REMAINING
GENERALLY EASTERLY AS HIGH PRESSURE BUILDS NORTH OF THE REGION.
PREV DISCUSSION... /ISSUED 126 AM EDT WED AUG 20 2014/
AVIATION...
WINDS WILL REMAIN EASTERLY FOR THE EAST COAST TERMINALS WHICH WILL
FAVOR THE BEST CHANCE FOR THUNDERSTORMS IN THE INTERIOR. AT THE
PRESENT TIME WE ARE NOT INCLUDING VCTS FOR THE EAST COAST
TERMINALS SINCE THE CONVECTION IS FORECAST TO DEVELOP WEST OF THE
EAST COAST TERMINALS. HOWEVER, INCLUDED VCSH FOR ALL TERMINALS
AFTER 15Z EXCEPT PBI. APF HAS THE GREATEST CHANCE OF PRECIPITATION,
AS THE EASTERLY FLOW FAVORS THUNDERSTORM DEVELOPMENT OVER THE
INTERIOR, AND SOMETIMES IT COULD AFFECT THE NAPLES AREA.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 92 78 91 78 / 30 10 30 10
FORT LAUDERDALE 92 81 91 80 / 20 10 30 10
MIAMI 91 80 91 80 / 30 10 30 10
NAPLES 91 78 92 78 / 50 10 50 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
SHORT TERM...52/PS
LONG TERM....52/PS
AREA FORECAST DISCUSSION
NWS JACKSON KY
1143 AM EDT WED AUG 20 2014
.UPDATE...
ISSUED AT 1143 AM EDT WED AUG 20 2014
A RATHER CHALLENGING FORECAST THIS MORNING. TAIL END OF FRONTAL
ZONE...BOUNDARY IS EVIDENT ACROSS THE MID WEST THIS MORNING AND WILL
PLAY A MAJOR ROLE IN OUR WEATHER OVER THE NEXT SEVERAL DAYS. BUILDING
RIDGE OF HIGH PRESSURE ALOFT AND TO OUR WEST WILL FORCE THIS BOUNDARY
TO THE EAST OVER THE NEXT 24 HOURS. THIS BOUNDARY WILL BECOME
INCREASINGLY ALIGNED WITH MID AND UPPER LEVEL FLOW PATTERNS AND
BECOME STATIONARY ACROSS THE MID OHIO VALLEY REGION. THEREAFTER IT
SERVES AS A FOCUS FOR CONVECTION AND THE OCCASIONAL CONVECTIVE
COMPLEX OF STORMS. ATTM IT APPEARS AT LEAST PART OF OUR AREA WILL
FEEL THE EFFECTS OF WEAK IMPULSES OF ENERGY RIDING OVER AND DROPPING
DOWN ALONG THE EAST SIDE OF THE RIDGE AXIS.
IMMEDIATE QUESTION IS WILL CURRENT UPSTREAM ACTIVITY OVER IA/IL
MANAGE TO MAKE IT INTO OUR AREA. MOST LIKELY ANSWER LIES WITHIN THE
SYNOPTIC PATTERN THAT IS TAKING SHAPE...BEST DESCRIBED AS AN ALMOST
IDEAL MCS GENERATOR. MODELS SEEM TO HAVE PICKED UP ON THIS AS WELL...
DEPICTING THE SOURCE OF MOISTURE/ENERGY...NAMELY BOUNDARY LAYER H925
TO H850 FLOW INTO THESE STORM COMPLEXES WEAKENING THROUGH THE DAY DUE
TO DIURNAL MIXING...THE INCREASING AGAIN AT NIGHT. THESE COMPLEXES
ONCE GENERATED THEN RIDE SOUTHEAST ALONG THE BOUNDARY. THAT BEING
SAID EXPECT THE CURRENT ACTIVITY ACROSS IA/IL TO WEAKEN A BIT
THROUGH THE DAY. BUT CONFIDENCE IS LOW THAT ACTIVITY WILL COME TO A
COMPLETE END. MOST RECENT RUNS OF THE RAP AND HRRR SUPPORT THIS LINE
OF THOUGHT AND REGIONAL SATELLITE DOES SHOW A DEFINITE WARMING TREND
TO CLOUD TOPS ATTM. DECIDED TO TRIM POPS DOWN JUST A BIT THROUGH THE
AFTERNOON BUT LEAVING ENOUGH TO TO ACCOUNT FOR ISOLD TO SCATTERED
CONVECTION ASSOCIATED WITH DIURNAL HEATING AND ACTIVITY THAT MAY FIRE
ALONG ANY RESIDUAL OUTFLOW BOUNDARIES. PREVIOUS FORECAST HAS POPS
INCREASING AGAIN TONIGHT WHICH IS IN LINE WITH CURRENT THOUGHTS AS
WELL...ESPECIALLY WITH THE SURFACE BOUNDARY SHIFTING TO THE EAST
ACROSS OUR AREA. ALSO TWEAKED HOURLY TEMPS AND WINDS TO BRING THE
GRIDS IN LINE WITH LATEST HOURLY OBS. FINALLY FRESHENED UP ZONES TO
REMOVE MORNING FOG WORDING.
UPDATE ISSUED AT 800 AM EDT WED AUG 20 2014
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL EXIT SOUTHEASTERN
KENTUCKY IN THE NEXT ONE TO TWO HOURS. ONCE THESE STORMS CLEAR THE
AREA...THERE MAY BE SOME ISOLATED TO SCATTERED CONVECTION RE-
DEVELOPING ACROSS EASTERN KENTUCKY THIS AFTERNOON DURING PEAK
HEATING. WILL STAY THE COURSE AND CONTINUE TO MENTION THE
POPS...HOWEVER SOME OF THE GUIDANCE HAS TRENDED DRIER...AND GIVEN THE
SUBSIDENCE FOLLOWING THE DEPARTING WAVE...WOULD NOT BE SURPRISED IF
CONVECTION IS EVEN MORE ISOLATED. UPDATES HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 357 AM EDT WED AUG 20 2014
A COMPLEX OF SHOWERS AND THUNDERSTORMS IS CURRENTLY SLIDING EAST
ACROSS THE OHIO VALLEY ASSOCIATED WITH A PASSING SHORT WAVE TROUGH.
THE MORE ORGANIZED PORTION OF THIS COMPLEX HAS BEEN CONFINED TO ALONG
AND NORTH OF THE MOUNTAIN PARKWAY. THE HRRR MODEL HAS NOT BEEN
HANDLING THIS FEATURE WELL THROUGH THE OVERNIGHT...OVERPLAYING THE
DEVELOPMENT TO THE SOUTH THAT HAS BEEN WEAK IN REALITY...WHILE
UNDERPLAYING WHERE CONVECTION HAS BEEN MORE ORGANIZED AND SUSTAINED.
EXPECT THIS COMPLEX TO KEEP MOVING EAST...AFFECTING LOCATIONS ALONG
AND NORTH OF THE MOUNTAIN PARKWAY FOR THE NEXT FEW HOURS...BEFORE
EXITING THE AREA BY 12Z. THERE WILL BE SOME SUBSIDENCE FOLLOWING THIS
DEPARTING SHORT WAVE FOR TODAY WORKING IN FROM WEST TO EAST...SO HAVE
TRIMMED THE POPS BACK A BIT...PEAKING IN THE 20 TO 30 RANGE FOR MOST
LOCATIONS DURING THE HOTTER PART OF THE DAY. HIGHS TODAY WILL RANGE
FROM 85 TO 90 DEGREES.
AS WE HEAD INTO TONIGHT...CONVECTION WILL BE ON THE DOWNWARD TREND
THROUGH 06Z...BUT THEN LOOKS TO INCREASE BETWEEN 06 AND 12Z...AS
ANOTHER SHORT WAVE TROUGH APPROACHES FROM THE NORTHWEST. POP CHANCES
WILL CONTINUE TO INCREASE THROUGH THE DAY ON THURSDAY WITH HEATING
AIDING THE MODEST FORCING FROM THE PASSING SHORT WAVE. HAVE MAINTAINED
THE BETTER POPS IN THE NORTHEAST...AND LESSER VALUES IN THE
SOUTHWEST...FURTHER REMOVED FROM THE BETTER FORCING. HIGHS WILL
RETURN TO THE 85 TO 90 DEGREE RANGE IN THE SOUTHWEST...WITH MID 80S
IN THE NORTHEAST...WHERE MORE PERSISTENT CLOUD COVER WILL RESIDE.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 335 AM EDT WED AUG 20 2014
THE EXTENDED PORTION OF THE FORECAST BEGINS ON THURSDAY NIGHT WITH A
SLOWLY BUILDING RIDGE OVER THE CENTRAL CONUS AND DIGGING TROUGHS
OVER THE NORTHWEST AND NORTHEAST. THIS GENERAL TREND CONTINUES
THROUGH THE ENTIRE EXTENDED PERIOD. DURING THIS PERIOD...QUITE A FEW
STRONG SHORTWAVES TRAVEL OVER THE BUILDING RIDGE IN THE CENTRAL
PLAINS AND INTO THE OH VALLEY AND GREAT LAKES REGION. THE FIRST WAVE
OF NOTE WILL BE THE SHORTWAVE MOVING THROUGH AT THE BEGINNING OF THE
EXTENDED. AFTER THIS...THE PATTERN TURNS INTO A MORE MCS DRIVEN
PATTERN FRIDAY THROUGH SUNDAY WITH ACTIVITY CENTERED AROUND WHAT THE
DAYS CONVECTION BRINGS AND IS DIURNALLY AFFECTED. THROUGH THE PERIOD
THE UPPER RIDGE SLOWLY WEAKENS AND DRIFTS EAST.
CONCERNING THE MODELS DURING THE EXTENDED...THE GFS AND EURO LOOK TO
BE RIGHT ON TRACK AND IN GOOD AGREEMENT. THOUGH...THE EURO LOOKS TO
CUT OFF ANY CONVECTION BY THE END OF THE EXTENDED AS THE RIDGE AXIS
SETS UP RIGHT OVER EASTERN KENTUCKY LEADING TO AN END TO ALL
DIURNALLY DRIVEN CONVECTION AND DISPLACING THE TRACK OF THE MCS MORE
TO THE NORTHEAST. BASED ON THE GOOD AGREEMENT...IT SEEMS TO BE A
GOOD CONSENSUS TO STAY CLOSE TO THE SOLUTION OF THE ALL BLEND MODEL.
THOUGH DEPENDING ON WHAT THE 00Z EURO DOES ON THE MONDAY AND TUESDAY
TIME FRAME FOR THE RIDGE AXIS RIGHT OVER THE AREA...MAY DROP POPS
BELOW THE ALL MODEL BLEND SOLUTION. WITH THE SOLUTION OF THE ALL
MODEL BLEND...THE BEST CHANCE OF POPS WILL BE DURING THE FRIDAY
THROUGH SUNDAY TIME FRAME AND LESS DURING THE MONDAY AND TUESDAY
TIME FRAME WHERE THE RIDGE WILL BE OVER EASTERN KENTUCKY AND HAVE
LEFT SLIGHT CHANCE MAINLY DURING THE AFTERNOON ON MONDAY AND
TUESDAY.
IN ADDITION TO THIS PATTERN...TEMPERATURES WILL BE ON THE INCREASE
IN EARNEST AS SOME OF THE WARMEST WEATHER OF THE ENTIRE SUMMER WILL
BEGIN TO SET IN FROM FRIDAY THROUGH THE REST OF THE EXTENDED. HIGH
TEMPERATURES WILL SURPASS 90 DEGREES IN SOME AREAS OF EASTERN
KENTUCKY AND HUMIDITY WILL BE ON THE INCREASE AS WELL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 815 AM EDT WED AUG 20 2014
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL EXIT OFF TO THE
SOUTHEAST IN THE NEXT HOUR OR TWO. IFR/LIFR FOG WILL LIFT OUT IN THE NEXT
HOUR...WITH A RETURN TO VFR CONDITIONS THROUGH THE REST OF THE DAY.
SOME ISOLATED TO SCATTERED CONVECTION WILL THREATEN AGAIN THIS
AFTERNOON...BUT COVERAGE IS EXPECTED TO BE LIMITED ENOUGH TO ONLY
MENTION VCTS FOR NOW. FOG WILL LIKELY RETURN AFTER 06Z TONIGHT...HOWEVER
ANOTHER UPPER LEVEL DISTURBANCE WILL LIKELY APPROACH BETWEEN 06 AND
12Z...BRINGING IN ADDITIONAL CLOUD COVER AND ALSO RENEWING THE
CONVECTIVE THREAT. THIS WILL LIKELY KEEP THE FOG FROM BECOMING TOO
DENSE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
UPDATE...RAY
SHORT TERM...GEOGERIAN
LONG TERM...SHALLENBERGER
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
ISSUED BY NATIONAL WEATHER SERVICE PADUCAH KY
1138 AM EDT Wed Aug 20 2014
...Forecast Update...
Issued at 1135 AM EDT Wed Aug 20 2014
Partly cloudy skies were noted across southern Indiana and central
Kentucky this morning. Temperatures ranged from the upper 70s to
near 80- in the east/northeast with lower 80s generally in the I-65
corridor and points west. From the KY Mesonet data and visible
satellite imagery, there appears to be boundary draped across the
southern part of the forecast area. This evident in the dewpoint
readings across southern KY which are in the middle 70s with only
upper 60s to lower 70s across our NE sections.
A decaying MCS over central IL will continue to spread mid-high
level cloudiness down into mainly western KY this afternoon. These
clouds along with the boundary in the region may serve as a focus
for convective development later this afternoon. The high
resolution convection allowing models have vastly different
solutions. The latest runs of the HRRR keep much of our region dry
thought the day with convection mainly developing out to our west.
While the NSSL WRF ARW runs develop convection up near CVG and drop
it SE into WFO JKL`s region. The mixed signals in the guidance make
this forecast particularly challenging this afternoon.
For now, have kept the current forecast on track. Current thinking
is that convection will probably start to develop over the next few
hours along the left over boundary...given multiple convectively
induced lifting mechanisms cross the region. Damaging winds and
perhaps some large hail will be possible with the storms this
afternoon as moderate instability combined with around 30 kts of
WNW flow aloft will be in place across the region.
.SHORT TERM (Now through Thursday)...
Issued at 340 AM EDT Wed Aug 20 2014
A complex short term forecast is in store with multiple rounds of
strong to potentially severe convection possible as potent
shortwaves topple a central CONUS ridge and dive southeast into the
Ohio Valley. In addition, the eastern edge of a warm front will
slowly lift north over the region over the next few days providing
focus for convection. Also left over boundaries from storms
will provide focus for renewed convection over the next few days
with convective activity peaking during the afternoon and evening
hours during best instability.
As of 315am this morning, convection over the Bluegrass region was
causing mainly very heavy rainfall and lots of lightning. A flood
advisory is effect for northern Harrison County KY through 6am this
morning due to training storms over that area. The Harrison County
mesonet has received 1.34 inches of rain so far with impressive
rainfall rates which may cause minor flooding issues.
Think that this complex of storms will move east of the area within
the next 1-2 hrs and we may see a dry period through the morning
hours. Expect a left over boundary from convection over central
Indiana yesterday evening to settle somewhere near the Ohio River
over portions of southern Indiana and north central Kentucky.
Believe this boundary will be key for redevelopment of convection
this afternoon.
Most short range models indicate a shortwave will dive south into
the area this evening. Ahead of this wave, expect the atmosphere to
become very unstable with only partly cloudy skies in the wake of
morning convection. Bulk shear will increase ahead of the wave as
early as 1-3pm this afternoon. This is when we may see convection
begin to fire in the region of the left over sfc boundary.
Convection should be enhanced in strength and coverage during the
evening hours as the shortwave passes through. It is a bit unclear
how long into the evening and overnight hours convection will
continue. It may survive for a prolonged period of time if a good
cold pool and outflow boundaries get going. At some point late
tonight into tomorrow morning expect a break in showers/storms.
Another notable shortwave looks to impact mainly northern KY and
southern Indiana with storms for Thurs afternoon/evening as well.
Models generally do not have a good handle on ongoing convection and
evolution so confidence is rather low on exact timing. However,
model soundings indicate increased bulk shear values with each wave
and excellent instability so storms will likely be strong to severe
in nature today through Thurs with damaging winds, large hail, and
torrential rainfall all possible. PWATs will hover in the 1.6-2
inch range resulting in some heavy rainers and potential flood
problems.
As for temperatures, think that highs will range from the upper 80s
to lower 90s today and tomorrow with locations west of I-65 likely
seeing max heat indices near 100 each afternoon. Low temperatures
tonight will be mild in the lower 70s.
.LONG TERM (Thursday night through Tuesday)...
Issued at 311 AM EDT Wed Aug 20 2014
Thursday night through Tuesday...
Expect a hot spell throughout the entire extended period, at least
through the middle portion of next week.
In an upper air pattern that we`ve not seen much of this summer,
strong 500mb ridging will develop initially across the lower
Mississippi Valley by Thursday evening, with longwave troughs
located over the Pacific Northwest and New England. The wavelength
of this trough-ridge-trough pattern will lead to a stagnant pattern.
The GFS for example holds this ridge in place through at least late
Monday, building it northwards towards the Commonwealth. We should
expect probably a week`s worth of hot sticky humid weather with
highs well into the 90s and warm overnight lows in the lower to mid
70s over the weekend and into the middle of next week. Rising Heat
Indices may be a concern for early next week.
In this type of pattern, shortwaves moving along the periphery of
500mb ridging can bring episodic convection. Initially, Thursday
night through Sunday, scattered thunderstorms may develop within a
northwest flow pattern along the northeastern edge of this building
ridge. This would favor southeastern Indiana, southern Ohio and the
northern Bluegrass for possible scattered thunderstorms,
concentrated during the afternoon and evening hours. Southwestern
Kentucky, closer to the warm temperatures aloft associated with this
ridge, will likely stay dry.
By Monday and Tuesday, think the entire region will be dry, as
ridging builds northwards into the Commonwealth.
&&
.AVIATION (12Z TAF Update)...
Issued at 650 AM EDT Wed Aug 20 2014
The main TAF concerns will be brief MVFR restrictions this morning
and convection timing.
MVFR cigs have worked into LEX this morning and expect them to
remain for the next few hours. Low clouds are also close to SDF but
think that they will remain just north of the terminal this
morning. BWG could see some light br but the window is quickly
closing for any MVFR restrictions so will keep them VFR this morning.
This evening a convective complex is expected to develop to
our northwest and dive south/southeast into the area. Ahead of this
complex of storms, additional cells may form over central KY. Felt
confident enough to include VCTS at the TAF sites for this issuance
as models have been persistent with this round of convection.
However, timing may need to be adjusted throughout the day today.
Winds will remain southerly through the TAF period generally 7
kts or less except in t-storms.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........MJ
Short Term.....AMS
Long Term......JSD
Aviation.......AMS
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
815 AM EDT WED AUG 20 2014
.UPDATE...
ISSUED AT 800 AM EDT WED AUG 20 2014
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL EXIT SOUTHEASTERN
KENTUCKY IN THE NEXT ONE TO TWO HOURS. ONCE THESE STORMS CLEAR THE
AREA...THERE MAY BE SOME ISOLATED TO SCATTERED CONVECTION RE-
DEVELOPING ACROSS EASTERN KENTUCKY THIS AFTERNOON DURING PEAK
HEATING. WILL STAY THE COURSE AND CONTINUE TO MENTION THE
POPS...HOWEVER SOME OF THE GUIDANCE HAS TRENDED DRIER...AND GIVEN THE
SUBSIDENCE FOLLOWING THE DEPARTING WAVE...WOULD NOT BE SURPRISED IF
CONVECTION IS EVEN MORE ISOLATED. UPDATES HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 357 AM EDT WED AUG 20 2014
A COMPLEX OF SHOWERS AND THUNDERSTORMS IS CURRENTLY SLIDING EAST
ACROSS THE OHIO VALLEY ASSOCIATED WITH A PASSING SHORT WAVE TROUGH.
THE MORE ORGANIZED PORTION OF THIS COMPLEX HAS BEEN CONFINED TO ALONG
AND NORTH OF THE MOUNTAIN PARKWAY. THE HRRR MODEL HAS NOT BEEN
HANDLING THIS FEATURE WELL THROUGH THE OVERNIGHT...OVERPLAYING THE
DEVELOPMENT TO THE SOUTH THAT HAS BEEN WEAK IN REALITY...WHILE
UNDERPLAYING WHERE CONVECTION HAS BEEN MORE ORGANIZED AND SUSTAINED.
EXPECT THIS COMPLEX TO KEEP MOVING EAST...AFFECTING LOCATIONS ALONG
AND NORTH OF THE MOUNTAIN PARKWAY FOR THE NEXT FEW HOURS...BEFORE
EXITING THE AREA BY 12Z. THERE WILL BE SOME SUBSIDENCE FOLLOWING THIS
DEPARTING SHORT WAVE FOR TODAY WORKING IN FROM WEST TO EAST...SO HAVE
TRIMMED THE POPS BACK A BIT...PEAKING IN THE 20 TO 30 RANGE FOR MOST
LOCATIONS DURING THE HOTTER PART OF THE DAY. HIGHS TODAY WILL RANGE
FROM 85 TO 90 DEGREES.
AS WE HEAD INTO TONIGHT...CONVECTION WILL BE ON THE DOWNWARD TREND
THROUGH 06Z...BUT THEN LOOKS TO INCREASE BETWEEN 06 AND 12Z...AS
ANOTHER SHORT WAVE TROUGH APPROACHES FROM THE NORTHWEST. POP CHANCES
WILL CONTINUE TO INCREASE THROUGH THE DAY ON THURSDAY WITH HEATING
AIDING THE MODEST FORCING FROM THE PASSING SHORT WAVE. HAVE MAINTAINED
THE BETTER POPS IN THE NORTHEAST...AND LESSER VALUES IN THE
SOUTHWEST...FURTHER REMOVED FROM THE BETTER FORCING. HIGHS WILL
RETURN TO THE 85 TO 90 DEGREE RANGE IN THE SOUTHWEST...WITH MID 80S
IN THE NORTHEAST...WHERE MORE PERSISTENT CLOUD COVER WILL RESIDE.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 335 AM EDT WED AUG 20 2014
THE EXTENDED PORTION OF THE FORECAST BEGINS ON THURSDAY NIGHT WITH A
SLOWLY BUILDING RIDGE OVER THE CENTRAL CONUS AND DIGGING TROUGHS
OVER THE NORTHWEST AND NORTHEAST. THIS GENERAL TREND CONTINUES
THROUGH THE ENTIRE EXTENDED PERIOD. DURING THIS PERIOD...QUITE A FEW
STRONG SHORTWAVES TRAVEL OVER THE BUILDING RIDGE IN THE CENTRAL
PLAINS AND INTO THE OH VALLEY AND GREAT LAKES REGION. THE FIRST WAVE
OF NOTE WILL BE THE SHORTWAVE MOVING THROUGH AT THE BEGINNING OF THE
EXTENDED. AFTER THIS...THE PATTERN TURNS INTO A MORE MCS DRIVEN
PATTERN FRIDAY THROUGH SUNDAY WITH ACTIVITY CENTERED AROUND WHAT THE
DAYS CONVECTION BRINGS AND IS DIURNALLY AFFECTED. THROUGH THE PERIOD
THE UPPER RIDGE SLOWLY WEAKENS AND DRIFTS EAST.
CONCERNING THE MODELS DURING THE EXTENDED...THE GFS AND EURO LOOK TO
BE RIGHT ON TRACK AND IN GOOD AGREEMENT. THOUGH...THE EURO LOOKS TO
CUT OFF ANY CONVECTION BY THE END OF THE EXTENDED AS THE RIDGE AXIS
SETS UP RIGHT OVER EASTERN KENTUCKY LEADING TO AN END TO ALL
DIURNALLY DRIVEN CONVECTION AND DISPLACING THE TRACK OF THE MCS MORE
TO THE NORTHEAST. BASED ON THE GOOD AGREEMENT...IT SEEMS TO BE A
GOOD CONSENSUS TO STAY CLOSE TO THE SOLUTION OF THE ALL BLEND MODEL.
THOUGH DEPENDING ON WHAT THE 00Z EURO DOES ON THE MONDAY AND TUESDAY
TIME FRAME FOR THE RIDGE AXIS RIGHT OVER THE AREA...MAY DROP POPS
BELOW THE ALL MODEL BLEND SOLUTION. WITH THE SOLUTION OF THE ALL
MODEL BLEND...THE BEST CHANCE OF POPS WILL BE DURING THE FRIDAY
THROUGH SUNDAY TIME FRAME AND LESS DURING THE MONDAY AND TUESDAY
TIME FRAME WHERE THE RIDGE WILL BE OVER EASTERN KENTUCKY AND HAVE
LEFT SLIGHT CHANCE MAINLY DURING THE AFTERNOON ON MONDAY AND
TUESDAY.
IN ADDITION TO THIS PATTERN...TEMPERATURES WILL BE ON THE INCREASE
IN EARNEST AS SOME OF THE WARMEST WEATHER OF THE ENTIRE SUMMER WILL
BEGIN TO SET IN FROM FRIDAY THROUGH THE REST OF THE EXTENDED. HIGH
TEMPERATURES WILL SURPASS 90 DEGREES IN SOME AREAS OF EASTERN
KENTUCKY AND HUMIDITY WILL BE ON THE INCREASE AS WELL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 815 AM EDT WED AUG 20 2014
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL EXIT OFF TO THE
SOUTHEAST IN THE NEXT HOUR OR TWO. IFR/LIFR FOG WILL LIFT OUT IN THE NEXT
HOUR...WITH A RETURN TO VFR CONDITIONS THROUGH THE REST OF THE DAY.
SOME ISOLATED TO SCATTERED CONVECTION WILL THREATEN AGAIN THIS
AFTERNOON...BUT COVERAGE IS EXPECTED TO BE LIMITED ENOUGH TO ONLY
MENTION VCTS FOR NOW. FOG WILL LIKELY RETURN AFTER 06Z TONIGHT...HOWEVER
ANOTHER UPPER LEVEL DISTURBANCE WILL LIKELY APPROACH BETWEEN 06 AND
12Z...BRINGING IN ADDITIONAL CLOUD COVER AND ALSO RENEWING THE
CONVECTIVE THREAT. THIS WILL LIKELY KEEP THE FOG FROM BECOMING TOO
DENSE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...GEOGERIAN
LONG TERM...SHALLENBERGER
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
930 AM EDT WED AUG 20 2014
.SYNOPSIS...
A STATIONARY BOUNDARY WILL REMAIN OVER THE REGION THROUGH THURSDAY.
THE BOUNDARY WILL SLOWLY DROP SOUTH AND WEST AS A COLD FRONT FRIDAY
AND HIGH PRESSURE OVER NEW ENGLAND WILL EXTEND INTO OUR AREA FOR THE
WEEKEND. HOWEVER...UNSETTLED CONDITIONS MAY PERSIST DURING THIS TIME
DUE TO PLENTY OF MOISTURE FROM THE ATLANTIC.
&&
.NEAR TERM /THROUGH TONIGHT/...
A SHORTWAVE TROUGH WILL APPROACH THE MID ATLANTIC THIS MORNING.
SHOWERS AND THUNDERSTORMS HAVE BEEN ONGOING ACROSS THE OHIO VALLEY
AND APPALACHIAN MTNS AND WILL BE MOVING ACROSS THE ALLEGHENY FRONT
THIS MORNING.
VISIBLE SATELLITE SHOWS MOSTLY SUNNY CONDITIONS WEST OF THE BLUE
RIDGE. FURTHER EAST...S-SE WINDS HAVE BANKED CLOUDS AGAINST THE BLUE
RIDGE MTNS SOUTH OF THE POTOMAC RIVER RESULTING IN LOW CLOUDS FOR
LOCATIONS ADJACENT TO THE MTNS THIS MORNING. THESE CLOUDS MAY
CREEP NORTHWARD BEFORE DISSIPATING THIS AFTERNOON. 12Z IAD RAOB
HAS ABOUT 500 J/KG OF SBCAPE AND AFTER MODIFYING IT FOR THE
AFTERNOON...INSTABILITY IS EXPECTED TO INCREASE TO AROUND 1000
J/KG. INSTABILITY SHOULD INCREASE MORE IF AN AREA RECEIVES MORE
HEATING. DEWPTS ARE EXPECTED TO STAY OR REACH THE UPPER 60S TO
AROUND 70 BY THE AFTERNOON AND AS MOISTURE MOVES IN FROM THE WEST...PWATS
WILL LIKELY INCREASE TO AROUND 1.8 INCHES. SHEAR IS
WEAK...AROUND 25KTS AND THUNDERSTORMS SHOULD STAY SUB-SEVERE
TODAY. HRRR HAS LINE OF SHOWERS AND THUNDERSTORMS MOVING EASTWARD
THROUGH THE MORNING AND REACHING THE BLUE RIDGE BY EARLY
AFTERNOON AND THE I-95 CORRIDOR LATE THIS AFTERNOON. ACTIVITY IS
MORE ISO-SCT FURTHER SOUTH AND THE BEST CHANCE FOR RAIN WILL BE
NORTH OF I-66 AS SHORTWAVE ENERGY MOVES TO THE NORTH. MAIN THREAT
IN ACTIVITY WILL BE HEAVY RAIN IN SHOWERS AND THUNDERSTORMS.
PREVIOUS DISCUSSION...
MAX TEMPS WILL RANGE FROM THE 70S IN THE MOUNTAINS TO THE MIDDLE
80S ACROSS MOST OTHER LOCATIONS.
COVERAGE IN CONVECTION SHOULD DIMINISH OVERNIGHT...BUT WITH THE
BOUNDARY NEARBY AND SHORTWAVE ENERGY MOVING THROUGH...A FEW SHOWERS
CANNOT BE RULED OUT. AREAS OF LOW CLOUDS AND FOG WILL DEVELOP LATE
TONIGHT AS WELL. WARM AND HUMID CONDITIONS WILL PERSIST WITH MIN
TEMPS RANGING FROM NEAR 60 IN THE ALLEGHENY HIGHLANDS TO THE LOWER
70S IN DOWNTOWN WASHINGTON AND BALTIMORE.
&&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
THE UPPER-LEVEL LOW WILL MOVE INTO NEW ENGLAND THURSDAY THROUGH
THURSDAY NIGHT. SHORTWAVE ENERGY WILL CONTINUE TO ROTATE THROUGH THE
AREA IN A NORTHWEST FLOW ALOFT. THE BOUNDARY WILL REMAIN NEARLY
STATIONARY FROM CENTRAL MARYLAND THROUGH CENTRAL VIRGINIA AND THE
WARM AND HUMID AIRMASS WILL REMAIN OVERHEAD. MORE SHOWERS AND
THUNDERSTORMS ARE EXPECTED WITH COVERAGE BEING SCATTERED TO
NUMEROUS...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS. MAX
TEMPS THURSDAY WILL RANGE FROM THE 70S IN THE MOUNTAINS TO THE MID
AND UPPER 80S ACROSS MOST OTHER LOCATIONS. MIN TEMPS THURSDAY NIGHT
WILL RANGE FROM THE LOWER 60S IN THE ALLEGHENY HIGHLANDS TO THE
LOWER 70S IN DOWNTOWN WASHINGTON AND BALTIMORE. PATCHY LOW CLOUDS
AND FOG ARE EXPECTED OVERNIGHT AS MOISTURE GETS TRAPPED UNDERNEATH
THE NOCTURNAL INVERSION.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
H5 PTTN MUCH MORE AMPLIFIED/ACTIVE THAN NORMAL FOR LT AUG...BUT THEN
AGAIN THIS HASNT BEEN A TYPICAL SUMMER. A SUBTROPICAL RDG WL BE
ANCHORED OVER THE MS VLY THRU MUCH OF THE PD. THAT LEAVES CWFA IN NW
FLOW ALOFT...AND TEMPS COOLER THAN CLIMO. WUD LOVE TO BE AS
DEFINITIVE W/ POPS. HWVR...SUBSIDENCE WL BE CONFINED TO OVER NEW
ENGLAND. WHILE AMS LKLY WONT BE OUTRIGHT CAPPED...THERE ARENT
SPECIFIC DISCERNABLE FORCING MECHANISMS EITHER...BUT THERE WL BE THE
JETSTREAM ABV AREA AT HIER LVLS. THAT LEAVES SENSIBLE WX SUSCEPTIBLE
TO MID-UPA DYNAMICS SUCH AS S/WV IMPULSES EMBEDDED W/IN MEAN LYR
FLOW. IT APPEARS AS THOUGH THERE WL BE SUCH A DISTURBANCE FRI NGT
INTO SAT. INSTBY MEAGER...AND BECOME INCREASINGLY LMTD AS SFC FLOW
BECOMES ELY.
BYD THAT...EVEN BROAD DETAILS BECOME PROBLEMATIC. BY ELY NXT WK...
RDGG SHUD RETROGRADE...PROVIDING A BETTER BET AT SOME DRY CONDS IN
THE CSTL PLAIN. STILL CANT RULE OUT A SHRA IN THE MTNS...BUT THE
CHCS FAR LESS.
&&
.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
MVFR CONDITIONS WILL CONTINUE AT CHO THIS MORNING. SCT MVFR
CONDITIONS ARE LIKELY AT IAD-DCA AS LOW CLOUDS CONTINUE TO MOVE
NORTHWARD AGAINST THE MTNS. A FEW SHOWERS AND THUNDERSTORMS ARE
POSSIBLE THIS AFTERNOON AND EVENING. MORE LOW CLOUDS AND FOG WILL
DEVELOP LATE TONIGHT INTO THURSDAY MORNING. SHOWERS AND
THUNDERSTORMS ARE POSSIBLE THURSDAY AND THURSDAY
NIGHT...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS.
FLGT RESTRICTIONS PROBABLE W/IN SHRA/TSRA THRU THE WKND. HWVR...
AREAL CVRG A WILD CARD. FRI NGT-SAT LOOK TO BE THE WETTEST PART OF
THE OUTLOOK ATTM.
&&
.MARINE...
A BOUNDARY WILL REMAIN NEAR THE WATERS THROUGH THURSDAY NIGHT...BUT
THE PRESSURE GRADIENT SHOULD BE WEAK ENOUGH TO PREVENT SCA CRITERIA
WINDS DURING THIS TIME. A FEW SHOWERS AND THUNDERSTORMS ARE
POSSIBLE...ESPECIALLY LATE THIS AFTERNOON THROUGH THIS EVENING...AND
AGAIN THURSDAY AFTERNOON AND THURSDAY NIGHT.
ATTM NO ADVYS XPCTD THRU THIS WKND. HWVR UNSTTLD CONDS WL PREVAIL...
AND CANNOT PRECLUDE A FEW MARINE WRNGS INVOF TSRA.
&&
.TIDES/COASTAL FLOODING...
AN ONSHORE FLOW WILL CONTINUE THROUGH TONIGHT...BUT IT WILL REMAIN
WEAK. THE FLOW MAY TURN MORE TOWARD THE SOUTHEAST WHICH WOULD CAUSE
WATER LEVELS TO BE SLIGHTLY HIGHER THAN THEY HAVE BEEN RECENTLY.
THIS WILL CAUSE WATER LEVELS TO BE CLOSE TO MINOR FLOODING
THRESHOLDS DURING THE HIGH TIDE CYCLE LATE TONIGHT INTO EARLY
THURSDAY MORNING.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BJL
NEAR TERM...BJL/HAS
SHORT TERM...BJL
LONG TERM...HTS
AVIATION...BJL/HAS/HTS
MARINE...BJL/HAS/HTS
TIDES/COASTAL FLOODING...BJL
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
549 AM CDT WED AUG 20 2014
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 323 AM CDT WED AUG 20 2014
MESO ANALYSIS THIS MORNING INDICATING HIGH DEGREE OF
MOISTURE/INSTABILITY IN PLACE OVER THE REGION WITH PWS OVER 1.5"
AND MUCAPES AROUND 2000 J/KG. MEANWHILE INTENSE LLVL MOISTURE ADV
WAS FEEDING CONVECTIVE ACTIVITY WHICH HAS BLOSSOMED OVER CNTRL NEB
AND CNTRL SD ALONG AXIS OF DEEP LYR MOIST CONVERGENCE/BNDRY LYR
THETA-E ADV/315K ISENTROPIC UPGLIDE.
LAST SEVERAL RUNS OF HIRES HRRR SUGGESTING LINE OF CONVECTION
ORIENTED NW-SE WILL FIRE OVER THE CWA SOMETIME TWD SUNRISE THIS
MORNING. HRRR THEN LIFTS ACTIVITY NEWD TWD THE UPPER MIDWEST AND OUT
OF THE CWA BY 18Z THIS AFTN.
HEADING INTO THIS WEEKEND...GOOD MODEL AGREEMENT HIGH PRESSURE DOME
WILL BUILD OVER THE SERN STATES WILL ACT AS A BLOCK RESULTING IN
UPSTREAM AMPLIFICATION OF UPPER TROF OVER THE WRN CONUS. IN
ADDITION...BULK OF PCPN ACTIVITY IS PROGGED TO BE NOCTURNAL IN
NATURE THE REST OF THIS WEEK WITH BULK OF RAINFALL FOUND MAINLY
NORTH OF THE CWA. HOWEVER...QUITE PROBABLE THE CWA WILL SEE ITS
FAIR SHARE OF MUCH NEEDED PCPN THE NEXT SEVERAL DAYS.
TONIGHT...EXPECT CONVECTION TO FIRE FROM ERN SD TO SW NEB ALONG
INSTABILITY AXIS WHERE BNDRY LYR THETA-E CONVG WILL BE MOST
PREVALENT. ACTIVITY PROGGED TO EVENTUALLY ORGANIZE INTO A COMPLEX
AND SLOWLY MIGRATE EWD OVER ERN SD OVERNIGHT. IS LIKELY THAT SRN
PORTION OF MCS WILL PUSH DEEP INTO THE CWA...THUS FEEL COMPELLED
PUSH POPS INTO THE LIKELY CAT DURING THE OVERNIGHT TONIGHT.
THURSDAY NIGHT CONVECTION NOT LOOKING ALL THAT IMPRESSIVE AT THIS
POINT AND ANY ACTIVITY THAT DOES DEVELOP WILL BE LIGHTLY SCATTERED
IN NATURE AT BEST. THEREFORE TOKEN LOW POPS SEEM TO BE THE BEST FIT
FOR NOW. FRIDAY NIGHT THOUGH LOOKING RATHER PROMISING FOR GENEROUS
RAINFALL ASSOCIATED WITH ANTICIPATED NIGHTTIME COMPLEX. ENVIRONMENT
AT THAT TIME WILL BE PRIME WITH WARM CLOUD DEPTH OF 4K METERS...PWS
MORE THAN 2"...KI AOA 40...LLVL JET MOISTURE TRANSPORT FEED. MOST
LIKELY THAT HEAVIER RAINFALL AMOUNTS WILL BE FOUND OVER THE NRN
CWA...THUS WILL MENTION IN ZFP.
.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 323 AM CDT WED AUG 20 2014
FEATURE OF INTEREST STILL IS UPPER TROF OVER WRN CONUS RESPONSE TO
BLOCKING HIGH PRESSURE DOME OVER THE SERN CONUS WITH RATHER COOL
CANADIAN AIRMASS SWEEPING INTO THE NRN/CNTRL PLAINS EARLY NEXT WEEK.
GOING FCST WITH MAX TEMPS GENERALLY IN THE MID/UPPER 70S
MON/TUES/WED STILL LOOK REASONABLE FOR NOW. PCPN CHANCES IN THE EXT
PDS REMAINS CENTERED AROUND VERY SLOW MOVING COLD FRONTAL LEADING
THE CANADIAN AIR MASS INTO THE REGION FOLLOWED BY POST FRONTAL PCPN
ASSOCIATED WITH APPROACHING UPPER TROF. WITH ECM/GFS QPF IN RATHER
GOOD AGREEMENT...HAVE DECIDED TO BUMP POPS UP MON-WED PDS.
&&
.AVIATION...(12Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 550 AM CDT WED AUG 20 2014
CONVECTIVE ACTIVITY THIS MORNING SHOULD STAY NORTHEAST THROUGH
EAST OF THE TAF SITES WITH A GENERAL THINNING OF CLOUDS THIS
MORNING. OUTFLOW COULD BRING MORE OF A ENE COMPONENT TO SFC
WINDS EARLY...ESPECIALLY AT KOFK...BUT THEY SHOULD BECOME SSE BY
LATE MORNING AND BECOME GUSTY AT ALL LOCATIONS THIS AFTN. A LOW
LEVEL JET WILL STRENGTHEN AGAIN TONIGHT AND IF SFC WINDS DECREASE
ENOUGH...LOW LEVEL WIND SHEAR CONDITIONS COULD DEVELOP. THIS WILL
BE FURTHER EVALUATED IN LATER TAFS. TSTMS WERE EXPECTED TO DEVELOP
LATE THIS AFTN/TNGT EITHER NEAR A WARM FRONT ALONG THE SD BORDER
OR IN AN AREA OF LOW PRESSURE OVER WRN NEBR. SOME OF THIS ACTIVITY
COULD APPROACH THE KOFK SITE AND A PROB30 GROUP WAS CARRIED TO
ACCOUNT FOR THE RISK THERE LATER TONIGHT.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...DEE
LONG TERM...DEE
AVIATION...CHERMOK
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
1029 AM EDT WED AUG 20 2014
.SYNOPSIS...
A WEAK COLD FRONT WILL CONTINUE TO MOVE THROUGH EASTERN NORTH
CAROLINA THIS MORNING...THEN LIFT BACK NORTH ACROSS THE AREA LATE
TODAY AND TONIGHT. THEN FRONT WILL LINGER THROUGH FRIDAY...THEN
FINALLY PUSH THROUGH FRIDAY NIGHT INTO EARLY SATURDAY. HIGH
PRESSURE WILL EXTEND SOUTH INTO THE REGION SUNDAY INTO MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1015 AM WED...LATEST SFC ANALYSIS SHOWS FRONTAL BOUNDARY
SOUTH OF THE AREA IN THE VICINITY OF CAPE FEAR LATE THIS MORNING.
WIDESPREAD FOG ACROSS THE AREAS THIS MORNING IS BURNING OFF
QUICKLY PER VISIBLE SATELLITE AND EXPECT IT TO BE PRETTY MUCH
DISSIPATED AROUND 15Z. ISOLATED SHOWERS PUSHING SOUTH ACROSS THE
PAMLICO SOUND THAT WILL AFFECT DARE...HYDE AND TYRRELL COUNTIES
FOR THE NEXT FEW HOURS. HRRR HAS THE SHOWERS SOUTH OF THE OBX
AROUND 17Z...OTHERWISE LITTLE CHANGE TO FORECAST TODAY. THE FRONT
WILL CONTINUE TO PUSH THROUGH THE VERY SOUTHERN CWA THIS
MORNING...THEN LIKELY LIFT BACK NORTH THIS AFTERNOON INTO TONIGHT.
COMBINED WITH A WEAK SHORTWAVE PIVOTING THROUGH THE UPPER LOW
ACROSS THE GREAT LAKES PROVIDING UPPER LEVEL SUPPORT FOR
CONVECTION. THE AIRMASS REMAINS UNSTABLE AND MOIST WITH PWATS
AROUND 1.75-2" AND EXPECT ISOLATED TO SCATTERED CONVECTION TO
DEVELOP THIS AFTERNOON. CONTINUED WITH SC/LOW CHANCE POPS. LOW
LEVEL THICKNESS VALUES SUPPORT HIGHS IN THE MID 80S TO LOWER 90S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
AS OF 715 AM WED...WEAK BOUNDARY WILL CONTINUE TO LIFT BACK INTO THE
AREA TONIGHT THEN STALL. ANY EVENING CONVECTION SHOULD WANE WITH
LOSS OF HEATING. THOUGH COULD SEE AN ISOLATED SHOWER/TSTM NEAR THE
ALBEMARLE SOUND REGION OVERNIGHT ASSOCIATED WITH SHORTWAVE MOVING
THROUGH THE MID-ATLANTIC REGION. AREAS OF FOG POSSIBLE AGAIN
OVERNIGHT INTO EARLY THURSDAY MORNING. LOWS IN THE UPPER 60S TO
LOWER 70S.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
AS OF 230 AM WED...LOW LEVEL WSW FLOW IN COMBINATION WITH DEVELOPING
WNW FLOW PATTERN ALOFT AND RISING THICKNESSES WILL SET UP VERY WARM
CONDITIONS EARLY IN THE FORECAST PERIOD. HIGHS THURSDAY WILL REACH
LOW TO POSSIBLY MID 90S INLAND WITH UPPER 80S AT THE BEACHES, WITH
HEAT INDICES AROUND 100 INLAND. RELATIVE LACK OF FORCING SHUD LIMIT
PRECIP CHANCES THRU EARLY THU AFTN BUT LINGERING WEAK SFC BNDRY AND
SUBTLE SHORT WAVE ENERGY IN THE UPPER FLOW MAY HELP TRIGGER A FEW
TSTORMS LATE IN THE AFTN.
UPPER TROF WILL DEEPEN OFF THE COAST LATE IN THE WEEK AND MOVE ONLY
SLOWLY FARTHER OFFSHORE THIS WEEKEND AND EARLY NEXT WEEK AS BLOCKY
PATTERN SETS WITH STRONG UPPER RIDGE BUILDING OVER THE MISSISSIPPI
VALLEY REGION. THIS DEVELOPING UPPER PATTERN WILL PLACE EASTERN NC
IN PERSISTENT NNW FLOW ALOFT AND SHORT WAVES MOVING THRU THE FLOW
WILL TRIGGER OCCASIONAL BOUTS OF PRECIPITATION THU NIGHT THRU SAT.
THIS PATTERN MAY ALSO FAVOR MCS DEVELOPMENT...HOWEVER TIMING THESE
SMALL SCALE SYSTEMS IN THE LONGER TERM WILL BE DIFFICULT. HAVE KEPT
CHANCE POPS IN THRU SAT. HIGH PRES WILL BUILD IN FROM THE N SUN AND
MON AND CONT INTO TUE WITH SOMEWHAT DRIER AIR AND LIMIT THREAT FOR
PRECIP...ESPCLY MON AND TUE. HIGHS WILL AGAIN REACH LOWER 90S INLAND
FRI THEN WITH NE FLOW SAT INTO EARLY NEXT WEEK EXPECT HIGHS MAINLY
LOW TO MID 80S.
&&
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
SHORT TERM /THROUGH TONIGHT/...
AS OF 1015 AM WED...WIDESPREAD FOG ACROSS RTES THIS MORNING IS
BURNING OFF QUICKLY THIS MORNING PER VISIBLE SATELLITE AND EXPECT
IT TO BE DISSIPATED BY 15Z OR SHORTLY AFTERWARD WITH PRED VFR
RETURNING. ISOLATED/SCATTERED CONVECTION EXPECTED AGAIN THIS
AFTERNOON AND EVENING. AREAS OF FOG POSSIBLE AGAIN OVERNIGHT AND
EARLY THURSDAY MORNING.
LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 230 AM WED...SOME FOG/ST WILL BE POSS EARLY THU MORN THEN
MAINLY VFR REST OF DAY WITH SOME WIDELY SCT TO SCT CONVECTION POSS
LATE. BOUTS OF SHRA AND TSRA EXPECTED THU NIGHT THRU SAT WITH SHORT
WAVES MOVING ACROSS IN NW FLOW ALOFT. THERE WILL LIKELY BE SOME BRIEF
PDS OF REDUCED CIGS/VSBYS WHEN SHRA/TSRA CROSS OTHERWISE MOSTLY VFR
EXPECTED. PRECIP CVRG EXPECTED TO DIMINISH A BIT SUNDAY AS HIGH
PRES AND A LITTLE DRIER AIR PUSHES IN FROM THE N...SHLD BE MAINLY
VFR.
&&
.MARINE...
SHORT TERM /THROUGH TONIGHT/...
AS OF 715 AM WED...WEAK FRONTAL BOUNDARY CONTINUES TO PUSH THROUGH
THE VERY SOUTHERN WATERS THIS MORNING...IT WILL THEN LIKELY LIFT
BACK NORTH THIS AFTERNOON INTO TONIGHT. LATEST OBS SHOW NW/NE WINDS
5-15KT AND SEAS 2-4FT. WINDS LESS THAN 15KT EXPECTED TODAY...THEN
LESS THAN 10KT TONIGHT WITH SEAS 2-3FT. WIND DIRECTIONS HOWEVER
WILL BE CHALLENGING TODAY ESP SOUTH OF LOOKOUT. LIKELY N/NW BEHIND
THE BOUNDARY EARLY THEN BACKING BECOMING SW THIS AFTERNOON AND
TONIGHT. NORTH OF LOOKOUT MAINLY N/NE TODAY BECOMING E/NE TONIGHT.
LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 230 AM WED...LIGHT AND VARIABLE WINDS THU MORN WILL BECOME S
AOB 10 KTS THU AFTN. SW WINDS EXPECTED 10 TO 15 KTS THU NIGHT AHEAD
OF APPROACHING FRONT. COLD FRONT WILL SLOWLY PUSH S ACROSS THE WTRS
FRI AND FRI NIGHT WITH WINDS BECOMING N/NE IN ITS WAKE WITH SPEEDS
MAINLY BELOW 15 KTS. NE WINDS EXPECTED OVER THE WEEKEND AS HIGH PRES
BUILDS IN FROM THE N WITH WEAK LOW WELL OFF THE CST. ECMWF HAS
TIGHTER GRDNT WITH DEEPER LOW OFF THE CST AND SHOWS WINDS NEAR 20
KTS...FOR NOW LEANED CLOSER TO GFS WITH SPEEDS MAINLY 10 TO 15 KTS.
SEAS WILL BE MAINLY 2 TO 3 FEET THU THRU SAT MORN. AS NE FLOW GRAD
INCREASE LATER SAT AND SUN WILL HAVE 4 FOOT SEAS DEVELOP OUTER WTRS.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...RF/CQD
NEAR TERM...SK/CQD
SHORT TERM...CQD
LONG TERM...BTC/RF
AVIATION...RF/SK/CQD
MARINE...RF/CQD
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1124 AM EDT WED AUG 20 2014
.SYNOPSIS...
A BROAD UPPER LEVEL RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE
MISSISSIPPI RIVER VALLEY OVER THE NEXT FEW DAYS AND LINGER FOR THE
REST OF THE WORK WEEK...RESULTING IN ABOVE NORMAL TEMPERATURES. A
WEAK COLD FRONT WILL THEN PUSH INTO THE AREA FROM NORTHEAST SATURDAY
AND BRING SOME MINOR RELIEF FROM THE HEAT.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 11 AM...A SMALL CLUSTER OF DEEP CONVECTION IS APPROACHING THE
NORTHERN NC MTNS ATTM...THUS POPS HAVE BEEN INCREASED TO LIKELY IN
THE AREAS NORTH OF I-26 ALONG THE TENN BORDER. THE PREVIOUS REMNANT
CONVECTIVE AREA DISSIPATED AS IT MOVED EAST OF THE MTNS. HOWEVER...
THE ATMOSPHERE IS HEATING STRONGLY DOWNSTREAM OF THE HIGH TERRAIN.
REGIONAL RAOBS PAINTED A RATHER STARK CONTRAST FROM THIS TIME
YESTERDAY...ESP AT KFFC...WHERE A LAYER OF NEAR-DRY ADIABATIC LAPSE
RATES WERE OBSERVED BETWEEN H8 AND H6. AS A RESULT...THE AIRMASS IS
RAPIDLY DESTABILIZING EAST OF THE MTNS...WITH CAPE ALREADY EXCEEDING
1500 J/KG ACROSS THE FOOTHILLS AS OF 14Z. IT APPEARS LIKELY THAT
CAPE WILL INCREASE TO THE NEIGHBORHOOD OF 3000 J/KG THIS AFTERNOON.
CONVECTION IS ALREADY SHOWING SIGNS OF FANNING OUT ALONG THE OUTFLOW
BOUNDARY ACROSS NORTHEAST TENN...AND WITH CAPE INCREASING STRONGLY
DOWNSTREAM...IT SEEMS ENTIRELY PLAUSIBLE THAT SCATTERED CONVECTION
WILL CONTINUE TO DEVELOP ALONG THE BOUNDARY AS IT PUSHES EAST OF THE
MTNS BY EARLY AFTERNOON (THE LATEST HRRR IS SUGGESTING A SIMILAR
SCENARIO). AS SUCH...POPS HAVE BEEN INCREASED BY 10-20 PERCENT IN
MOST AREAS THIS AFTERNOON...WITH 40 POPS NOW BEING FEATURED AS FAR
SOUTHEAST AS THE I-85 CORRIDOR.
POPS HAVE ALSO BEE INCREASED FOR THIS EVENING. AN AXIS OF CAPE >
3000 IS ALREADY BEING ANALYZED ACROSS MIDDLE TENN INTO SE KENTUCKY.
SHORT TERM GUIDANCE ALSO DEPICTS A CORRIDOR OF 20-30KTS OF LOW LEVEL
SHEAR THIS AFTERNOON FROM EASTERN KENTUCKY INTO SOUTHWEST NC. A
CONSENSUS OF MESOSCALE MODEL GUIDANCE WOULD SUGGEST ORGANIZED MCS
DEVELOPMENT IN THESE AREAS BY LATE AFTERNOON...POSSIBLY DROPPING
SOUTHEAST INTO THE FORECAST AREA THIS EVENING. HOW THIS PLAYS OUT
FOR OUR AREA MAY DEPEND LARGELY UPON THIS AFTERNOON/S CONVECTIVE
EVOLUTION...BUT IT SEEMS THE AREA MOST LIKELY TO BE AFFECTED WOULD
BE ACROSS (ROUGHLY) THE NORTHWEST HALF OF THE FORECAST AREA...WHERE
POPS WERE INCREASED TO 40-50 PERCENT THIS EVENING. LOWERING FREEZING
LEVELS AND LARGE DCAPE SHOULD SUPPORT A RISK OF ISOLATED LARGE HAIL
AS WELL AS DAMAGING WINDS...WITH THE POTENTIAL FOR AN ENHANCED
DOWNBURST RISK WITH ANY UPSCALE ORGANIZATION.
1030 UTC UPDATE...POPS HAVE BEEN ADJUSTED PER RADAR TRENDS...WITH A
DECREASE EARLY ON. SKY COVER WAS UPDATED FROM INFRARED SATELLITE
IMAGERY...ALSO RESULTING IN A DECREASE. AREAS OF FOG WERE REDUCED
BASED ON OBSERVATIONS AND DEW POINT DEPRESSIONS.
AT 300 AM EDT TUESDAY...AN UPPER TROUGH WILL AMPLIFY ALONG THE EAST
COAST TODAY...WHILE AN UPPER RIDGE BUILDS NORTH OVER THE MS RIVER
VALLEY. SEVERAL WEAK SHORTWAVES WILL CROSS OUR AREA TODAY AND
TONIGHT IN NW FLOW ALOFT....WHILE A COLD FRONT ADVANCES SLOWLY FORM
THE NE. IT IS UNCLEAR WHETHER THE FRONT WILL MAKE IT VERY FAR INTO
OUR AREA...BUT ITS GENERAL PROXIMITY MAY FOCUS CONVECTION ACROSS OUR
NORTHERN TIER OF COUNTIES. EVEN IF THE FRONT REMAINS OFF TO THE
NORTHEAST...OUR AREA WILL BE IN A MOIST UNSTABLE AIR MASS...AND
PASSING SHORTWAVES WILL PROVIDE SUPPORT FOR CONVECTION. MOISTURE
WILL BE SOMEWHAT LIMITED...AND STEERING FLOW GREAT ENOUGH TO KEEP
CELLS MOVING...LIMITING THE POTENTIAL FOR HEAVY RAINFALL. ROBUST
CAPE WILL BE PRESENT...AND DRY AIR WILL BE AVAILABLE FOR EVAPORATIVE
COOLING...PROVIDING SUPPORT FOR WIND GUSTS AND HAIL. HIGH
TEMPERATURES WILL BE SLIGHTLY ABOVE NORMAL.
SOME ELEVATED INSTABILITY WILL LINGER THROUGH TONIGHT...AND IF ANY
MCS ROUNDING THE CORNER OF THE RIDGE REACHES OUR AREA...IT MAY WELL
SURVIVE. STEERING FLOW AND A LACK OF DEEP MOISTURE WILL LIMIT HEAVY
RAINFALL POTENTIAL. MINIMUM TEMPERATURES WILL RUN ABOVE NORMAL IN A
MOIST AIRMASS.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM WEDNESDAY...A LARGE UPPER RIDGE WILL PERSIST ACRS THE
LWR-MID MS VALLEY...EXTENDING EAST ACRS THE SOUTHEAST STATES THRU
THE SHORT TERM. THE LATEST GUIDANCE SHOWS THAT A RING OF FIRE
PATTERN WILL SET UP...WITH A SERIES OF SHORTWAVES AND ASSOCIATED
CLUSTERS OF CONVECTION WILL RIDE OVER TOP OF THE RIDGE...FROM THE
UPR MIDWEST/SRN GREAT LAKES...TO THE MID ATLANTIC. IT LOOKS LIKE
MOST OF THE ASSOCIATED ACTIVITY WILL STAY NORTH OF THE CWFA.
HOWEVER...THE NRN ZONES (GENERALLY I-40 CORRIDOR AND NORTH)...MAY
GET BRUSHED BY A POSSIBLE MCS AT SOME POINT. NOT MUCH CHANGE WAS
MADE TO THE POPS. STILL EXPECT AT LEAST A HANDFUL OF
DIURNALLY-DRIVEN CONVECTION...AS STEEP MID LVL LAPSE RATES REMAIN
ATOP THE REGION. MODELS ARE TRENDING WARMER FOR THURSDAY AND
FRIDAY...SO I BUMPED UP TEMPS ABOUT A CATEGORY...EVEN MORE IN THE NW
NC PIEDMONT...WHERE WE PREVIOUSLY THOUGHT A BACKDOOR COLD FRONT
WOULD PUSH IN BY FRIDAY. THIS RESULTS IN ABOVE NORMAL TEMPS...WITH
UPR 80S IN THE MTN VALLEYS AND MID-UPR 90S ACRS THE PIEDMONT.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 315 AM WEDNESDAY...THE UPPER FLOW LOOKS TO BECOME MORE
NORTHERLY ATOP THE CWFA FOR SATURDAY AND SUNDAY...AS RIDGE AXIS
DRIFTS SLIGHTLY EAST...WHILE A LARGE TROF REMAINS NEARLY STATIONARY
JUST OFF THE EAST COAST. WHILE THE MEDIUM RANGE GUIDANCE HAS DELAYED
THE TIMING OF A BACKDOOR COLD FRONTAL PASSAGE BY A FULL DAY...THEY
STILL SHOW IT COMING THRU...WITH SLIGHTLY COOLER TEMPS AND INCREASED
CHC FOR PRECIP. BOTH THE 00Z/20 GFS AND ECMWF SHOW WEDGE-LIKE
CONFIGURATION FOR SUNDAY...WITH A 1021-1023 MB SFC HIGH OVER THE
CANADIAN MARITIMES...NOSING A RIDGE AXIS SW ALONG THE EAST COAST.
LIGHT NELY LLVL FLOW AND INCREASED CLOUDS SHUD KEEP TEMPS CLOSER TO
NORMAL...ESP SUNDAY.
FOR MONDAY AND TUESDAY...THE SFC HIGH SINKS SOUTHWARD...KEEPING
COOLER LLVL THICKNESSES ACRS THE REGION...AND CONTINUED LIGHT ELY
LLVL FLOW. I WILL FCST TEMPS BACK TO NORMAL...EVEN SLIGHTLY BELOW
NORMAL IN THE NW NC PIEDMONT...WITH CONTINUE SLGT CHC TO CHC POPS.
&&
.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...FOG HAS FAILED TO DEVELOP...AND THE DEW POINT DEPRESSION
REMAINS THREE DEGREES. CALM WINDS ARE EXPECTED TO BECOME LIGHT NE
THIS MORNING...THEN BACK TO SW BY AFTERNOON...BEFORE VEERING TO WNW
THIS EVENING. CONVECTIVE CHANCES REMAINS TOO LOW TO MENTION. LOW
CLOUDS ARE EXPECTED TO INCREASE TODAY...BUT WITHOUT ENOUGH COVERAGE
FOR A LOW VFR CIG. GUIDANCE DID NOT FAVOR FOG WEDNESDAY MORNING...
BUT IF IT RAINS THIS AFTERNOON OR EVENING...FOG WOULD BE MORE LIKELY.
ELSEWHERE...FOG HAS NOT DEVELOPED AS EXPECTED...EXCEPT IN A FEW NON
TAF SITES THAT RECEIVED BETTER RAINFALL YESTERDAY...AND THE LITTLE
TN RIVER VALLEY. CALM FOOTHILL WINDS MAY BRIEFLY COME UP FROM THE N
OR W THIS MORNING...BEFORE BACKING TO SW. KAVL WINDS WILL REMAIN
CHANNELED FROM THE NW. CONVECTIVE CHANCES ARE ONLY GREAT ENOUGH FOR
A MENTION AT KAVL THIS AFTERNOON. GUIDANCE FAVORED VERY LOW VSBY IN
FOG IN THE MOUNTAINS TONIGHT...BUT BASED ON RECENT PERFORMANCE...
ONLY MVFR VSBY WILL BE CARRIED AT KAVL.
OUTLOOK...SCT AFTERNOON CONVECTION AND PATCHY EARLY MORNING FOG WILL
REMAIN IN THE FORECAST THROUGH THE WEEK. THERE WILL ALSO BE
INCREASING CHANCES FOR REMNANT ORGANIZED CONVECTION APPROACHING THE
AREA FROM THE NW DURING THE LATE NIGHT/EARLY MORNING HOURS.
CONFIDENCE TABLE...
15-21Z 21-03Z 03-09Z 09-15Z
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAVL HIGH 100% HIGH 100% HIGH 100% MED 62%
KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...ARK
NEAR TERM...JAT/JDL
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...JAT
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1008 AM CDT WED AUG 20 2014
.UPDATE...
ISSUED AT 1008 AM CDT WED AUG 20 2014
CURRENT CONVECTION IN EASTERN NEBRASKA CONTINUES TO FILTER
NORTHEASTWARD INTO PARTS OF NORTHWEST IA...EXTREME NORTHEAST NEB
AND FAR SOUTHEAST SD THIS MORNING. THIS ACTIVITY IS ASSOCIATED
WITH A 700MB WAVE...MARKED BY DECENT MID LEVEL FRONTOGENESIS AND
STRONG MID LEVEL SPEED CONVERGENCE IN THAT AREA. SIGNALS BASED OFF
OF THE 12Z NAM CONTINUE TO POINT AT A GRADUAL WEAKENING OF THESE
FEATURES INTO MIDDAY...ALBEIT THERE ARE SOME INDICATIONS THAT THE
MID LEVEL CONVERGENCE MAY MAKE IT ALL THE WAY TOWARD THE IA GREAT
LAKES AREA AND STORM LAKE EARLY THIS AFTERNOON. SO THAT WILL NEED
MONITORED TO SEE IF WE NEED TO INCREASE AFTERNOON POPS IN THAT
AREA.
THIS CONVECTION HAS REALLY FOULED UP THE LOW LEVEL AND SURFACE
BOUNDARIES THIS MORNING. AT THIS TIME...IT APPEARS THAT THE
CURRENT POSITION OF THE MAIN WARM FRONT IS STILL AROUND THE OMAHA
AREA PUSHED SOUTHWARD BY THE RAINFALL. THE VARIOUS SHORTER RANGE
MODELS ARE ALL OVER THE MAP IN HOW THEY LIFT THE FRONT...OR FRONTS...
NORTHWARD THIS AFTERNOON AND EVENING. FURTHERMORE...THE NEW 12Z
NAM HAS THE MAIN SHORT WAVE LIFTING OUT MUCH FURTHER TO THE
NORTHWEST AND NORTH OF OUR FORECAST AREA TONIGHT...WITH A LOBE OF
UPPER QG FORCING ARCING SOUTHWARD INTO OUR AREA THIS EVENING FROM
THE PARENT SHORT WAVE TO OUR NORTH. SO FOR TONIGHT...THE ACTUAL WAVE
MAY NOT BE MUCH OF A PLAYER FOR OUR FORECAST AREA. IN ADDITION...THE
SURFACE WIND SHIFT TO THE WEST DOES NOT TAKE PLACE UNTIL TOMORROW.
SO ANY TORNADIC ACTIVITY WILL LIKELY HAVE TO BE CONFINED TO NEAR
THE NORTHWARD LIFTING WARM FRONT WHICH IS DIFFICULT TO PROG.
FOLLOWING THE 4KM NAM AND HRRR AS GUIDES SINCE THEY ARE VERY CLOSE...
IT APPEARS THAT ONE WARM FRONTAL BOUNDARY SCOOTS NORTHWARD WITH
THE WARM AIR ADVECTION TODAY...EVENTUALLY SETTING UP AND STALLING
GENERALLY FROM CENTRAL ND...TO NORTHEAST SD...AND DOWN TO JUST
NORTH OF MARSHALL MN THIS EVENING. BUT THERE IS A SECOND BOUNDARY
AS WAS SHOWN YESTERDAY GENERALLY EXTENDING FROM LOW PRESSURE IN
WEST CENTRAL SD...TO NEAR CHAMBERLAIN AND SIOUX CITY FROM 21Z TO
03Z TODAY...THEN WASHES OUT LIKELY DUE TO THE SHORT WAVE PASSAGE
TO OUR NORTHWEST. AFTER ALL OF THIS MORNING AND MIDDAY CONVECTION
IN OUR SOUTHERN ZONES...WORRIED THAT THE SOUTHERN PART OF THIS
SECOND WARM FRONT IN OUR SOUTHERN ZONES COULD BE CAPPED OFF INTO
THE EARLY EVENING HOURS. THIS WOULD INCLUDE THE SIOUX CITY...
YANKTON AND STORM LAKE AREAS. BUT FURTHER WEST TOWARD CENTRAL SD
WHERE STRONGER HEATING SHOULD OCCUR...THAT AREA COULD HAVE ENOUGH
LOW LEVEL CURVATURE TO SPAWN ISOLATED TORNADOES THIS EVENING...
AROUND THE CHAMBERLAIN AND MITCHELL AREAS...POSSIBLY EXTENDING
NORTHWARD THEN THROUGH THE EVENING CLOSER TO HIGHWAY 14 IN OUR
SOUTH DAKOTA ZONES. THE AFOREMENTIONED SURFACE LOW TO THE WEST
SHOULD ALSO AID IN LOW LEVEL CURVATURE IN OUR FAR WESTERN ZONES.
SO THIS APPEARS TO BE THE AREA RIGHT NOW FOR THE BEST CHANCE FOR
TORNADIC ACTIVITY THIS EVENING...AT LEAST WITH THE CURRENT
ANALYSIS. A BROADER RISK OF SEVERE WEATHER IS CERTAINLY WARRANTED
THROUGH THE FORECAST AREA INTO THE MIDDLE OF THE NIGHT ALONG THE
UPPER QG FORCING LOBE WHICH WAS MENTIONED ABOVE. WILL CONTINUE TO
MONITOR FOR THE LATEST TRENDS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT WED AUG 20 2014
SHOWERS AND THUNDERSTORMS EXPANDING THIS MORNING ALONG AND JUST
SOUTH OF THE MISSOURI RIVER IN AN AREA OF INCREASING ISENTROPIC LIFT
ON THE EDGE OF THE LOW LEVEL JET. THESE STORMS SHOULD GENERALLY
REMAIN SUB SEVERE WITH BRIEF HEAVY RAIN...ALTHOUGH A FEW MARGINALLY
SEVERE HAIL REPORTS ARE POSSIBLE. NOT REALLY A STRAIGHT FORWARD
FORECAST AS WE GO THROUGH THE THE DAY TODAY INTO TONIGHT REGARDING
CONVECTIVE EVOLUTION. THOUGHT IS THE ELEVATED CONVECTION THIS
MORNING WILL GENERALLY BEGIN TO WEAKEN AND DISSIPATE BY MID MORNING
AS THE AREA OF ISENTROPIC LIFT MOVES NORTH INTO DRIER AIR AND WE
HAVE THE DIURNAL WEAKENING OF THE LOW LEVEL JET. THIS IS SUPPORTED
BY A MAJORITY OF THE HI RES GUIDANCE. STILL SHOULD BE QUITE A BIT OF
MID LEVEL CLOUDINESS THAT STICKS AROUND THROUGH THE DAY...AND
POSSIBLY AN ISOLATED ELEVATED SHOWER OR STORM. BUT GENERALLY
THINKING THE DAY ENDS UP MAINLY DRY...UNTIL WE SEE A REGENERATION
THIS EVENING INTO THE OVERNIGHT...WHICH WILL BE DISCUSSED BELOW.
HIGHS TODAY TRICKY AS WELL GIVEN CLOUD COVER UNCERTAINTY. WILL
CONTINUE TO GO MIDDLE GROUND FOR HIGHS...WITH THE CLOUD COVER...HIGH
BOUNDARY LAYER MOISTURE...AND SOUTHEASTERLY WINDS LIMITING MIXING.
STILL SHOULD SEE MID TO UPPER 80S...WHICH COMBINED WITH THE HIGH
DEWPOINTS WILL RESULT IN HEAT INDICES FROM THE UPPER 80S TO MID
90S...HIGHEST ALONG THE MISSOURI RIVER.
MAIN FOCUS OF THIS FORECAST IS ON SEVERE WEATHER CHANCES THIS
AFTERNOON AND TONIGHT. THROUGH THE DAY A WARM FRONT WILL WORK ITS
WAY NORTH...SETTING UP SOMEWHERE ACROSS THE CWA BY THIS EVENING.
THIS WILL ENHANCE LOW LEVEL SHEAR...WITH 0 TO 1 KM SHEAR EXPECTED TO
BE 15 TO 20 KTS. GOOD TURNING OF THE WINDS WITH HEIGHT WILL ALSO
RESULT IN DEEP LAYER SHEAR OF 40 OR MORE KTS...SUFFICIENT FOR
SUPERCELLS. MLCAPE SHOULD BE PLENTIFUL AS WELL WITH MOST LOW LEVELS
AND STEEP LAPSE RATES ALOFT RESULTING IN VALUES OF 2000 TO 3000
J/KG. AM CONCERNED ABOUT LOW LEVEL LAPSE RATES AND STABILITY THOUGH.
MODEL SOUNDINGS SHOW A PRETTY GOOD CAP IN PLACE FOR MUCH OF THE DAY.
LOW LEVEL FORCING DOES NOT SEEM STRONG ENOUGH TO OVERCOME THIS FOR
MOST OF THE DAY...WHICH SHOULD KEEP SURFACE BASED CONVECTION AT BAY.
THE UPPER WAVE WILL PASS BY TO OUR NORTH THIS AFTERNOON AND
EVENING...BUT SHOULD PASS TOO FAR NORTH TO AID TOO MUCH IN
CONVECTIVE DEVELOPMENT...AS 700 AND 500 MB HEIGHT FALLS ARE MINIMAL
TO NON EXISTENT. THUS CONVECTIVE DEVELOPMENT WILL RELY MAINLY ON
FORCING FROM THE WEST TO EAST MOVING COLD FRONT AND THE INCREASING
LOW LEVEL JET TOWARDS 0Z. PREFER TIMING AND PLACEMENT CLOSE TO THE
06Z 4KM NAM...AND 4KM NMMB. THIS WOULD GIVEN CONVECTIVE INITIATION
ACROSS CENTRAL SOUTH DAKOTA...WITH STORMS MOVING TOWARDS CHAMBERLAIN
AND HURON BETWEEN 6PM AND 9PM. GIVEN THE AMPLE CAPE...STORMS SHOULD
BE ABLE TO THEN PROGRESS ACROSS MUCH OF THE CWA...APPROACHING
INTERSTATE 29 AFTER 10 PM AND THE EASTERN CWA AFTER MIDNIGHT. GIVEN
THE GOOD MODEL AGREEMENT WENT WITH LIKELY POPS MOST AREAS...STAYED
SHY OF GOING CATEGORICAL GIVEN THAT THERE IS STILL A CHANCE THE
STORMS PEEL OFF TO THE NORTH CLOSER TO THE BETTER UPPER SUPPORT.
IN GENERAL THE SPC SLIGHT RISK AND PROBABILITIES SEEM GOOD. GIVEN
THE STEEP LAPSE RATES ALOFT AND GOOD SHEAR...LARGE HAIL OF TENNIS
BALL SIZE WILL INITIALLY BE A THREAT. THIS VERY LARGE HAIL THREAT
SHOULD MAINLY BE CLOSER TO WHERE STORMS INITIATE...LIKELY THE
VICINITY OF THE JAMES RIVER OR WEST. AS STORMS MOVE EAST...SOME
LARGE HAIL WILL STILL BE POSSIBLE...BUT THE STRONG WIND THREAT
SHOULD ALSO INCREASE. TORNADO THREAT IS UNCERTAIN GIVEN THE
UNCERTAINTY ON WHETHER STORMS BECOME NEAR SURFACE BASED. BUT GIVEN
THE SHEAR MENTIONED ABOVE...CAN NOT RULE OUT A TORNADO OR
TWO...GREATEST THREAT AGAIN APPEARS TO BE WEST OF INTERSTATE
29...PROBABLY EVEN ALONG OR JUST WEST OF THE JAMES RIVER. HEAVY RAIN
WILL ALSO BE LIKELY IN ANY STORMS...WITH PWATS UP TO 3 STANDARD
DEVIATIONS ABOVE NORMAL. STORMS SHOULD BE MOVING ENOUGH TO PREVENT A
BIG FLASH FLOOD RISK...ALTHOUGH LOCALIZED FLOODING WOULD BE POSSIBLE
IN THE HEAVIER STORMS.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 341 AM CDT WED AUG 20 2014
THURSDAY LOOKS WARM...DRY AND HUMID AS UPPER LEVEL RIDGING BUILDS
ACROSS THE REGION. MAIN CONCERN ON THURSDAY WILL BE HEAT INDICES.
WHILE NOT QUITE TO ADVISORY LEVELS COULD SEE SOME LOWER TO MIDDLE
90S FOR HEAT INDICES WHICH WILL FEEL PRETTY HOT GIVEN THE EXPECTED 5
TO 10 MPH WIND.
THURSDAY NIGHT INTO FRIDAY WILL SEE A TROUGH OF LOW PRESSURE SWING
ONTO THE PLAINS WHICH WILL BRING A GRADUALLY INCREASING THREAT FOR
THUNDERSTORMS. JUST A SLIGHT CHANCE THURSDAY NIGHT THEN BECOMING
MUCH MORE LIKELY LATE FRIDAY AFTERNOON AND FRIDAY NIGHT. ISOLATED
SEVERE THUNDERSTORMS AS WELL AS HEAVY RAIN WILL BE A THREAT. FRIDAY
LIKELY TO BE PRETTY WARM AND HUMID...ESPECIALLY THE SOUTHEAST HALF
OF THE CWA. HEAT INDICES LIKELY 90 TO 95 IN THESE AREAS.
IN THE OUTER PERIODS (SATURDAY THROUGH TUESDAY)...A FAIRLY STRONG
TROUGH OF LOW PRESSURE IS FORECAST TO MOVE ACROSS THE NORTHERN
PLAINS SATURDAY NIGHT INTO SUNDAY NIGHT. THE TIMING AND STRENGTH ARE
FAIRLY CONSISTENT IN THE LATEST MODELS SO WILL CONTINUE WITH MID
RANGE POPS DURING THIS TIME. ALSO LOOKS LIKE A DECENT CHANCE FOR
SOME SPOTTY HEAVY RAINFALL AS THE UPPER LEVEL FLOW LOOKS TO POSSIBLY
BECOME PARALLEL TO THE LOW LEVEL BOUNDARY...WHICH COULD SUPPORT SOME
TRAINING OF THUNDERSTORMS. A LITTLE TOO FAR OUT TO REALLY NAIL THIS
DOWN BUT SOMETHING TO WATCH FOR. AS THE WAVE PASSES COOLER AIR WILL
SETTLE INTO THE AREA AND WITH CONTINUED TROUGHING TO THE WEST THE
THREAT FOR SHOWERS AND THUNDERSTORMS...AS WELL AS ADDITIONAL CLOUD
COVER...WILL ALSO CONTINUE. TEMPERATURE GUIDANCE IN THIS TIME FRAME
IS ALREADY BELOW NORMAL AND SEE NO REAL REASON TO STRAY TOO FAR FROM
THAT. STATISTICALLY A GOOD SIGNAL WITH THE GFS MEX GUIDANCE BELOW
CLIMATOLOGICAL NORMALS AND THE ENSEMBLE MEAN OUTPUT COOLER YET WHICH
IS USUALLY A BIG HINT TO STAY BELOW THE COLDER MEN TEMPERATURES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1054 PM CDT TUE AUG 19 2014
VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. LIGHT AND
VARIABLE WINDS WILL INCREASE FROM THE SOUTHEAST AROUND 10 TO 20 KT
LATE TONIGHT INTO WEDNESDAY MORNING. SHOWERS AND THUNDERSTORMS MAY
BUILD INTO THE MISSOURI VALLEY LATE TONIGHT THROUGH DAYBREAK...BUT
ACTIVITY WILL LIKELY DIMINISH IN COVERAGE BY LATE MORNING THROUGH
THE END OF THE TAF PERIOD. SHOWERS AND THUNDERSTORMS WILL REDEVELOP
IN OUR NORTHWESTERN COUNTIES AFTER 21Z...LIKELY CLOSER TO 00Z.
SCATTERED THUNDERSTORMS SPREAD ACROSS THE REST OF THE AREA AFTER
00Z...WITH THE GREATEST POTENTIAL ALONG AND NORTH OF I-90.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...MJ
SHORT TERM...CHENARD
LONG TERM...08
AVIATION...
AREA FORECAST DISCUSSION
NWS AUSTIN/SAN ANTONIO TX
ISSUED BY NATIONAL WEATHER SERVICE BROWNSVILLE TX
1104 AM CDT WED AUG 20 2014
.DISCUSSION...UPPER LEVEL STORM SYSTEM CONTINUES TO SLOWLY WEAKEN
JUST SOUTHEAST OF THE AREA. 15/16Z SURFACE OBSERVATIONS AND
MORNING SOUNDINGS CONTINUE TO SUPPORT THE IDEA OF SEABREEZE
SHOWERS/THUNDERSTORMS BUILDING UP IN THE AFTERNOON ALONG THE
COASTAL BEND AND MOVING INTO ROUGHLY THE EASTERN QUARTER OF THE
AREA...WHICH WORKS WELL WITH LAST FEW HOURS OF HRRR RUNS ON
COVERAGE AND INTENSITY. TEMPERATURES AND WINDS ALSO LOOK ON
TRACK...NO SHORT TERM CHANGES PLANNED. /68-JGG/
&&
.PREV DISCUSSION... /ISSUED 624 AM CDT WED AUG 20 2014/
AVIATION...
MVFR CONDITIONS HAVE BROKEN OUT ACROSS THE I-35 CORRIDOR THIS MORNING.
EXPECT THIS TO CONTINUE THROUGH ABOUT 17Z BEFORE VFR CIGS RETURN.
WITH THE MOIST SOUTHERLY FLOW FROM THE GULF OF MEXICO CONTINUING
WE EXPECT MVFR STRATUS TO RETURN TONIGHT AROUND 08Z. DEL RIO MAY
SEE A COUPLE HOURS OF MVFR CIGS THIS MORNING...SO HAVE MAINTAINED
THE TEMPO GROUP FROM 13Z TO 15Z FROM PREVIOUS TAF PACKAGES. WITH THE
EXCEPTION OF THIS MORNING DRT WILL BE VFR THROUGH THE PERIOD.
WINDS WILL CONTINUE TO BE STRONG AND GUSTY AT TIMES. SOUTH TO
SOUTHEAST WINDS AT 10-15 KNOTS CAN BE EXPECTED THIS MORNING
GUSTING AT TIMES TO 20 KNOTS THIS AFTERNOON. WINDS CALM SLIGHTLY
OVERNIGHT...BACK DOWN TO AROUND 10 KNOTS...BEFORE PICKING UP
AGAIN ON THURSDAY.
PREV DISCUSSION... /ISSUED 311 AM CDT WED AUG 20 2014/
SHORT TERM (TODAY THROUGH THURSDAY)...
SHOWERS AND THUNDERSTORMS HAVE DISSIPATED ACROSS THE WESTERN
COUNTIES AND AM NOT EXPECTING MUCH IN THE WAY OF ADDITIONAL
ACTIVITY. THE UPPER TOUGH/SHEAR AXIS RESPONSIBLE FOR THE 48 HOURS
OF ACTIVITY HAS WEAKENED AND LIFTED TO THE NORTHEAST. THERE IS A
SLIGHT CHANCE OF SEA BREEZE SHOWERS AND THUNDERSTORMS ACROSS THE
COASTAL PLAINS COUNTIES THIS AFTERNOON. PW VALUES THEN DROP OFF
AND WILL KEEP A DRY FORECAST ACROSS ALL OF SOUTH CENTRAL TEXAS ON
THURSDAY. HIGHS TODAY AND THURSDAY WILL BE PERSISTENT...IN THE
UPPER 90S TO NEAR 100 DEGREES FOR MUCH OF THE AREA.
LONG TERM (THURSDAY NIGHT THROUGH TUESDAY)...
A MOSTLY DRY FORECAST WILL CONTINUE THROUGH SUNDAY. MOISTURE WILL
REMAIN RATHER SPARCE AND THIS SHOULD LIMIT THE ACTIVITY. CANT
COMPLETELY RULE OUT A STRAY SHOWER ON ANY GIVEN AFTERNOON...BUT
THE CHANCES WERE TOO LOW TO MENTION AT THIS TIME. PW VALUES
INCREASE TO NEAR 2 INCHES ACROSS THE SOUTHEASTERN COUNTIES ON
MONDAY AND THIS SHOULD BE SUFFICIENT TO WARRANT A MENTION OF
THUNDERSTORMS IN THIS AREA MONDAY. MODELS ARE SHOWING THIS
INCREASE IN MOISTURE TO BE SHORT LIVED WITH PW VALUES RETURNING TO
BELOW 1.8 INCHES TUESDAY. TEMPERATURES IN THE EXTENDED WILL
CONTINUE TO BE PERSISTENT WITH HIGHS IN THE UPPER 90S TO NEAR 100
DEGREES AND LOWS IN THE MIDDLE TO UPPER 70S ACROSS MUCH OF THE
AREA.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM
AUSTIN BERGSTROM INTL AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM
NEW BRAUNFELS MUNI AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM
BURNET MUNI AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM
DEL RIO INTL AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM
GEORGETOWN MUNI AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM
HONDO MUNI AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM
SAN MARCOS MUNI AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM
LA GRANGE - FAYETTE REGIONAL MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM
SAN ANTONIO INTL AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM
STINSON MUNI AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE/AVIATION...99
SYNOPTIC/GRIDS...99
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1014 AM EDT WED AUG 20 2014
.SYNOPSIS...
A WEAK STATIONARY FRONT WILL REMAIN IN THE AREA THROUGH THE REST
OF THE WEEK. UPPER LEVEL DISTURBANCES TRACKING EAST AND SOUTHEAST
ACROSS THE BOUNDARY WILL BRING SCATTERED SHOWERS AND STORMS TO THE
REGION EACH DAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 955 AM EDT WEDNESDAY...
BAND OF DEEP CONVECTION CONTINUES TO PUSH SE OUT OF THE MOUNTAIN
EMPIRE REGION INTO THE BLUE RIDGE ATTM AND EXPECT THIS AXIS TO
PERSIST UNTIL PERHAPS TOPPING THE FOOTHILLS IN THE NEXT HOUR OR
SO. THIS DESPITE LACK OF INSTABILITY AHEAD OF THE SHRA/TSRA
COMPLEX AS FEED OF BETTER CAPES AND THETA-E ADVECTION OFF TO THE
WEST PROVIDING SUPPORT. THIS AHEAD OF THE MID LEVEL SHORTWAVE
TROUGH THAT IS CURRENTLY APPROACHING THE WESTERN SLOPES AND ALONG
THE RESIDUAL SURFACE FRONT THAT HAS BACKDOORED SW INTO SW VA EARLY
THIS MORNING.
ALTHOUGH EXPECTING THIS PRECIP TO FADE...COMBINATION OF EARLY
CLOUDS/SHRA OVER THE WEST AND LINGERING FOG/STRATUS IN THE EASTERN
WEDGE WILL MAKE THINGS TRICKY IN REGARDS TO POSSIBLE RENEWED
AFTERNOON CONVECTION. MOST EARLIER GUIDANCE AND CURRENT SHORT TERM
SOLUTIONS WANT TO REDEVELOP TSRA ALONG THE BLUE RIDGE BEFORE
SLIDING THIS EAST INTO EARLY EVENING AS THE TROUGH AXIS LIFTS NE.
HOWEVER THE LATEST HRRR ONLY SHOWS ISOLATED COVERAGE BLUE RIDGE
AFTER CURRENT SHRA FIZZLES WHILE THE 12Z NAM SLOWER IN HOLDING OFF
MOST NEW CONVECTION UNTIL LATE OR EARLY EVENING EAST WITH SOME
WEAK CAPPING ALOFT UNDER RESIDUAL CLOUDS IN THE WAKE OF THE
CURRENT COVERAGE. THUS HAVE ADJUSTED POPS DOWN SOME IN THE FAR
WEST AND TRIMMED LIKELYS DOWN BLUE RIDGE BEHIND THE ONGOING
COVERAGE BEFORE BEEFING UP OUT EAST MID/LATE AFTERNOON AS CAPES
RECOVER LATE TO 1-2K J/KG. HIGH TEMPS WILL AGAIN GET OFF TO A
SLOW START IN SPOTS WITH LATE DAY HIGHS MOST SPOTS PENDING ADDED
SHRA/TSRA WITH PERHAPS THE FAR WEST BEING THE WARMEST WITH MORE
SUN EARLIER BEHIND THE CURRENT COVERAGE.
PREVIOUS VALID DISCUSSION...
AN UPPER LEVEL TROUGH OF LOW PRESSURE IS MOVING THROUGH THE GREAT
LAKES WITH LOBE OF VORTICITY TRAILING SOUTH INTO THE OHIO VALLEY.
THIS FEATURE HAS RESULTED IN A PERSISTENT AREA OF LIFT ASSOCIATED
WITH SHOWERS AND THUNDERSTORMS. AS OF 08Z/4AM...NUMEROUS SHOWERS
AND STORMS WERE OCCURRING FROM WESTERN PA INTO EASTERN OHIO AND
NORTHEAST KY. OUTFLOW FROM THIS COMPLEX OF THUNDERSTORMS IS
EXPECTED TO MAKE ITS WAY OVER THE MOUNTAINS TODAY.
MODELS DO NOT SEEM OVERLY CONFIDENT THIS OUTFLOW WILL MAKE IT
OVER THE MOUNTAINS...INDICATING WEAKENING AND A GRADUAL DEMISE OF
ACTIVITY. MATTER OF FACT THE SYNOPTIC MODELS DON`T PRODUCE MUCH IN
THE WAY OF RAINFALL AT ALL ACROSS OUR CWA...MOS POPS GENERALLY LESS
THAN 40 PERCENT.
ATTM PREFER NOT TO IGNORE THE OBVIOUS...WHICH IS A MODEST LOOKING
UPPER LEVEL TROF...ASSOCIATED WITH A HEALTHY LOOKING AREA OF
SHRA/TSRA...THE OUTFLOW OF WHICH SHOULD PASS THROUGH OUR FORECAST
AREA TODAY. THE ONLY THING THAT KEPT ME FROM GOING WITH
CATEGORICAL POPS IS THE POTENTIAL TIMING OF THE ACTIVITY AS IT
CROSSES THE MOUNTAINS. BASED ON CURRENT PROGRESSION...SHOWERS WILL
MOVE INTO THE WV MOUNTAINS DURING THE MORNING...THEN PROGRESS EAST
REACHING THE BLUE RIDGE TOWARD NOON...THEN EAST OF THE MTNS EARLY
THIS AFTERNOON. THIS EARLIER SORT OF TIMING SUGGESTS DEBRIS CLOUDS
WILL OVERSPREAD THE CWA EARLY AND LIMIT FULL INSOLATION THUS
LIMITING INSTABILITY.
THAT SAID...THINK AREA OF SHOWERS WITH EMBEDDED THUNDER WILL
CROSS THE FORECAST AREA...BUT IN A WEAKENED STATE. GREATEST
COVERAGE WILL BE FROM THE VIRGINIAS NORTHWARD CLOSER TO THE UPPER
SUPPORT FROM THE SHORT WAVE TROUGH...THE STRONGER DYNAMIC LIFT
MOVING FROM THE OHIO VALLEY INTO PA/NY. HAVE PLACED THE HIGHEST
POPS ACROSS WV/VA CLOSER TO THE SUPPORT FROM THE UPPER TROF...AND
WHERE THE OUTFLOW WILL HAVE THE BEST CHANCE OF MAKING IT OVER THE
MOUNTAINS AND HELP FOCUS RENEWED DEEP CONVECTION. FARTHER
SOUTH...FROM THE VA/NC BORDER SOUTHWARD...COVERAGE WILL BE LESS
AND MORE SCATTERED IN NATURE. WITH LESS COVERAGE COMES THE
OPPORTUNITY FOR MORE SUN. MORE SUN SUGGESTS WARMER
TEMPERATURES...AND WARMER TEMEPERATURES WILL YIELD GREATER
INSTABILITY PROVIDING STRONGER UPDRAFTS. AS SUCH CAN`T RULE OUT A
STRONG PULSE STORM OR TWO...ESPECIALLY WHERE MORE SUN
MATERIALIZES.
WENT BLO MOS GUIDANCE FOR TEMPERATURES ACROSS THE VIRGINIAS WHERE
MORE CLOUD COVER IS ANTICIPATED TODAY. THE WARMEST TEMPERATURES
WILL BE ACROSS NORTH CAROLINA WHERE MORE SUN IS ANTICIPATED.
PASSAGE OF THE UPPER TROUGH WILL BRING AN END TO MOST OF THE STORM
ACTIVITY THIS EVENING...FOLLOWED BY ANOTHER FOGGY NIGHT WITH
AREAS OF FOG AND PATCHY DENSE FOG DEVELOPING ACROSS THE FORECAST
AREA. IF SKIES CAN COMPLETELY CLEAR...THIS WOULD BE MOST IDEAL FOR
RADIATION FOG. THERE WERE SEVERAL REPORTS IN THE NEW RIVER VALLEY
WITH DENSE FOG EARLY WEDNESDAY MORNING. THINK IT WILL BE A REPEAT
AGAIN EARLY THURSDAY MORNING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
AS OF 330 AM WEDNESDAY...
THE REGION WILL REMAIN IN AN ACTIVE WEATHER PATTERN DURING THIS
PORTION OF THE FORECAST. A STRONG UPPER HIGH PRESSURE WILL BE
SITUATED ACROSS THE MID-MISSISSIPPI VALLEY. A DEEPENING UPPER
LOW/TROUGH WILL BE POSITIONED OFF THE COAST OF NEW ENGLAND. OUR AREA
OF THE COUNTRY WILL BE SANDWICHED BETWEEN THE TWO WITHIN NW-SE
ORIENTED MID-LEVEL BAROCLINIC ZONE...WITH AN ASSOCIATED SURFACE
BACKDOOR COLD FRONT EITHER OVER...OR VERY CLOSE TO THE REGION BY THE
START OF THE WEEKEND.
THE ABOVE SCENARIO POINTS TOWARD A PERIOD WITH AT LEAST SCATTERED
SHOWERS IN THE FORECAST EACH DAY AND NIGHT...AND SOME AFTERNOON AND
EVENING STORMS. WHAT IS A LITTLE HARDER TO NAIL DOWN WILL BE THE
WINDOWS OF OPPORTUNITY FOR LIKELY TO CATEGORICAL CHANCES OF
PRECIPITATION IN ASSOCIATION WITH PERIODICAL UPPER LEVEL SHORTWAVE
TROUGHS HEADING SOUTHEAST ALONG THIS BAROCLINIC ZONE AND THROUGH OUR
REGION. EACH MODEL SEEMS TO HAVE A DIFFERENT TAKE ON TIMING AND
TRACK.
EYEBALLING A CONSENSUS OF THE GUIDANCE POINTS TOWARD THURSDAY
AFTERNOON AND EVENING AS ONE POTENTIAL TIME THAT WOULD WARRANT
HIGHER POPS...ESPECIALLY ACROSS THE WESTERN AND NORTHERN PARTS OF
THE REGION. ANOTHER OPPORTUNITY MAY BE FRIDAY NIGHT ACROSS MAINLY
NORTHERN AND EASTERN PARTS OF THE AREA. FINALLY...SATURDAY NIGHT MAY
PROVE TO BE A THIRD OPPORTUNITY FOR ALL OF THE REGION...ESPECIALLY
CENTRAL AND WESTERN PORTIONS.
AT THIS TIME...CONFIDENCE IS NOT THERE TO OFFER A CATEGORICAL...75
PERCENT OR HIGHER...CHANCE OF PRECIPITATION FOR ANY ONE OF THE THREE
SCENARIOS LISTED ABOVE. HOWEVER...WILL CONTINUE...OR ADD...A
FORECAST OF LIKELY POPS TO THE FIRST AND SECOND SCENARIOS. FOR THE
THIRD SCENARIO...WILL OFFER A FORECAST JUST SHY OF LIKELY POPS.
TEMPERATURES THROUGH THE PERIOD ARE EXPECTED TO GRADUALLY COOL AS
THE BAROCLINIC ZONE MAKES PROGRESS WESTWARD. THE COMBINATION OF MORE
CLOUD COVER AND MORE PRECIPITATION...ALONG WITH LOWER HEIGHTS WILL
CONTRIBUTE TO THIS. BY SATURDAY...THE SURFACE COLD FRONT MAY BE
BISECTING THE REGION FROM NW-SE...THUS YIELDING NOTABLY COOLER
TEMPERATURES AT LEAST FOR THE CENTRAL AND NORTHEAST PARTS OF THE
AREA.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 130 PM EDT TUESDAY...
THE WEEKEND THROUGH EARLY NEXT WEEK WILL BE CHARACTERIZED BY THE
BATTLE BETWEEN LARGE UPPER RIDGE TO OUR WEST TRYING TO BUILD INTO
SOUTHERN APPALACHIANS...WHILE TROUGH OFF NEW ENGLAND COAST DEEPENS
WHILE CLOSING OFF AND CONTINUES TO APPEAR THAT IT WILL SET UP CLOSE
ENOUGH TO COAST TO PUSH BACK DOOR FRONT THROUGH AND WELL SOUTH OF
THE AREA THROUGH THE WEEKEND...BEFORE LIKELY WEAKENING AND ALLOWING
MORE INFLUENCE OF THE RIDGE TO BE FELT BY TUES...ESPECIALLY ACROSS
WESTERN PARTS OF THE AREA IF WEAK/SHALLOW BOUNDARY LAYER WEDGE IS IN
PLACE EARLY IN THE DAY BEFORE MIXING OUT OVER THE EAST. WHILE
SURFACE WEDGE FRONT MAY BE WELL TO THE SOUTH DURING MUCH OF THIS
PERIOD...WITH STRONGEST SOUTHWARD PUSH ON SATURDAY...THE 850
BOUNDARY AND MOST LIKELY TRACK FOR UPPER S/WV ENERGY FROM THE NW IS
LIKELY TO BE RIGHT OVER THE BLACKSBURG FORECAST AREA...AND THUS GOOD
CHANCE FOR SHOWERS/THUNDERSTORMS THROUGH THIS ENTIRE PERIOD. TIMING
MOST LIKELY WINDOWS REMAINS TRICKY...AS MANY OF THESE WAVES ARE
STRONGLY INFLUENCE BY CONVECTIVE COMPLEXES THAT WILL DEVELOP WELL
UPSTREAM. LIKE THE TRENDS OVERALL THAT 12Z GFS IS TAKING...NOT ONLY
WITH RETURN TO SHARPER AMPLITUDE PATTERN...BUT IDEA OF TWO DISTINCT
WAVES HEADING FOR THE WESTERN PART OF OUR FORECAST AREA...ONE
SATURDAY AND ANOTHER ONE SUNDAY. EXACT TIMES MAY HELP DETERMINE IF
THERE WILL BE ENOUGH INSTABILITY...WHICH WOULD LIKELY BE LIMITED TO
THE FAR WEST NEAR EDGE OF WEDGE BOUNDARY...BUT PERHAPS THE BIGGER
CONCERN IS RAINFALL THAT IS LIKELY TO IMPACT THE SAME AREAS AT LEAST
A COUPLE OF DAYS IN A ROW.
THERE COULD BE ANOTHER WAVE FOR MONDAY...BUT AS RIDGE ATTEMPTS TO
BUILD IN AND TROUGH TO THE EAST AND ASSOCIATED WEDGE WEAKEN WHAT MAY
TEND TO OCCUR IS MORE DIURNAL POP-UP CONVECTION ALONG AND NEAR THE
WESTERN PERIPHERY OF THE WEDGE BOUNDARY IN OUR WESTERN FORECAST AREA
AS THE ATMOS DESTABILIZES MORE. BY TUESDAY THE SUPPORT TO KEEP WEDGE
IN PLACE SHOULD BE WEAKENING AS TROUGH LIFTS AND SFC HIGH SHIFTS
MORE EAST OF THE AREA...AND OVERALL IT LOOKS A LITTLE DRIER...BUT
NOT SURE ALL POPS CAN BE REMOVED.
GIVEN PATTERN WE`VE BEEN IN...REALLY DON`T HAVE CONFIDENCE TO DRY IT
OUT OR WARM IT UP TOO FAST...SO WILL LEAN TOWARD STRONGER INFLUENCE
OF THE WEDGE THROUGH THIS PERIOD AND BETTER CHANCES FOR
PRECIP...WHICH WILL HELP STRENGTHEN THE WEDGE TOO. UNDERCUT EVEN
COOLER ECMWF A LITTLE BIT FOR HIGHS...WITH A BIT MORE WARMING FOR
TUESDAY. BUT IN THE FAR SOUTHWEST THINGS MAY BE ABLE TO WARM UP VERY
QUICKLY A DAY OR TWO EARLIER THAN THIS IF THE WEDGE CAN BREAK AND
SOME OF THE INFLUENCE OF THE BIG UPPER RIDGE CAN BE REALIZED. THIS
WILL EVENTUALLY RESULT IN A SIGNIFICANT WARM UP FOR OUR ENTIRE
AREA...BUT AM THINKING IT WILL NOT COME UNTIL MIDDLE OF NEXT WEEK.
&&
.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
AS OF 200 AM EDT WEDNESDAY...
BKN LINE OF SHRA/TSRA WILL CROSS THE FORECAST AREA TODAY.
SHRA/TSRA WILL PASS THROUGH THE MTNS THIS MORNING CROSSING
BLF/LWB/BCB BETWEEN 12-15Z/8-11AM...THEN MOVE EAST OF THE MTNS
AROUND MID-DAY WITH POTENTIAL FOR SHOWERS AND POSSIBLE
THUNDERSTORM VCNTY OF ROA/LYH/DAN DURING THE EARLY/MID AFTERNOON.
AN UPPER LEVEL TROF OF LOW PRESSURE WILL MOVE EAST ACROSS THE
GREAT LAKES AND OHIO VALLEY TODAY...AND INTO NEW ENGLAND
THURSDAY. THE TROF AXIS IS ASSOCIATED WITH A LINE OF SHOWERS AND
THUNDERSTORMS WHICH WILL MOVE THROUGH THE MOUNTAINS THIS MORNING
AND INTO THE PIEDMONT THIS AFTERNOON.
STORMINESS SHOULD CLEAR THE FORECAST AREA BY 22Z/6PM THIS EVENING
WITH ACTIVITY MOVING EAST. AREAS OF FOG WILL THEN RE-DEVELOP
ACROSS THE AREA TONIGHT WITH AREAS OF MVFR AND POTENTIAL FOR IFR
VSBYS AGAIN THURSDAY MORNING.
EXTENDED AVIATION... WEATHER CONDITIONS WILL CONTINUE TO BE
UNSETTLED AND HIGHLY VARIABLE FOR THE NEXT FEW DAYS AS A
STATIONARY FRONT REMAINS STALLED OVER THE MID ATLANTIC.
UPPER LEVEL DISTURBANCES WILL BE MOVING THROUGH PERIODICALLY
RESULTING IN PERIODS OF SHOWERS AND THUNDERSTORMS.
DUE TO THE HIGH MOISTURE CONTENT OF THE AIR...EXPECT STRATUS AND
FOG DURING THE OVERNIGHT PERIODS WITH AREAS OF MVFR/IFR MOST
PRONOUNCED BETWEEN MIDNIGHT AND 9AM EACH DAY. MODELS ARE INDICATED
THAT A DEEPER EASTERLY SORT OF WIND FLOW WILL SETUP FOR THIS
UPCOMING WEEKEND. THIS SUGGEST THAT LOW CIGS MAY PERSIST EVEN
DURING THE DAYTIME PERIODS...SATURDAY AND SUNDAY...WITH WIDESPREAD
MVFR CONDITIONS ACROSS THE AREA THIS WEEKEND DUE TO MOISTURE
BANKING UP AGAINST THE EAST SIDE OF THE APPALACHIANS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...SK
NEAR TERM...JH/PM
SHORT TERM...DS
LONG TERM...SK
AVIATION...PM
AREA FORECAST DISCUSSION
NWS PUEBLO CO
307 PM MDT WED AUG 20 2014
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 238 PM MDT WED AUG 20 2014
UPR LEVEL LOW IS SITTING ALONG THE SRN CA COAST TODAY AND IS
EXPECTED TO MOVE LITTLE IN THE NEXT 24 HOURS. WV SATELLITE IMAGES
SHOWING DRIER AIR HAS WORKED IT WAY INTO WRN CO TODAY. HRRR AND RAP
SHOWING MAINLY ISOLD PCPN COVERAGE THIS EVENING OVER WESTERN
PORTIONS OF THE FORECAST AREA...WITH ISOLATED TO SCT COVERAGE OVR
THE ERN MTS AND SERN PLAINS. A WEAK BOUNDARY IS FORECAST TO MOVE
INTO THE PALMER DVD AREA EARLY THIS EVENING AND THEN WORK ITS WAY
SOUTH. THIS BOUNDARY MAY HELP KICK OFF ADDITIONAL CONVECTION. THERE
COULD BE A FEW LINGERING SHOWERS OR TSTMS OVR THE SERN PLAINS...BUT
THINK THAT MOST OF THE PCPN SHOULD END BY 06Z.
ON THU...IT DOES NOT LOOK ALL THAT MOIST OVR THE FORECAST AREA.
PRECIPITABLE WATER VALUES OVR WRN AREAS ARE FORECAST TO BE SIMILAR
TO TODAY...WITH DRIER CONDITIONS OVR ERN AREAS. AS A RESULT THE
FORECAST MODELS SHOW MAINLY ISOLD TO SCT POPS OVR THE MTNS IN THE
AFTERNOON HOURS...WITH POSSIBLY A FEW STORMS OVR THE LOWER
ELEVATIONS. HIGH TEMPS FOR THU SHOULD BE AROUND AVERAGE IN THE HIGH
VALLEYS...WITH SLIGHTLY ABOVE NORMAL READINGS OVR THE SERN PLAINS.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 238 PM MDT WED AUG 20 2014
NOT MUCH CHANGE TO THE FORECAST THINKING WITH THE GFS COMING INTO
LINE WITH THE ECMWF AND NAM SOLUTIONS. ENSEMBLES ARE STILL
DISPLAYING QUITE A BIT OF SPREAD BY EARLY NEXT WEEK...BUT
CONFIDENCE IS A HIGHER THAN IT WAS YESTERDAY IN A FORECAST
SOLUTION.
AN UPPER LEVEL DISTURBANCE OVER SOUTHERN CALIFORNIA IS FORECAST TO
EJECT NORTHEAST ACROSS COLORADO ON FRIDAY. EXPECT A FEW SHOWERS
AND THUNDERSTORMS TO BE ONGOING THURSDAY EVENING AND DISSIPATING
THROUGH MIDNIGHT OVER THE MOUNTAINS...WITH PERHAPS A FEW LINGERING
SHOWERS OVER THE PALMER DIVIDE INTO NORTHEAST COLORADO INTO EARLY
FRIDAY MORNING.
FRIDAY HAS THE POTENTIAL TO BE INTERESTING. THE UPPER DISTURBANCE
OVER ARIZONA WILL EJECT ACROSS COLORADO THROUGH FRIDAY EVENING.
MODELS QUICK TO ADVECT MOISTURE NORTH ACROSS COLORADO...AND SHEAR
LOOKS TO INCREASE TO AROUND 30 KTS OR SO BY THE AFTERNOON WITH
MODEST INSTABILITY. EXPECT SHOWER AND THUNDERSTORM DEVELOPMENT BY
MID MORNING FRIDAY ALONG THE CONTINENTAL DIVIDE...AND SPREADING
EAST INTO THE I-25 CORRIDOR BY EARLY IN THE AFTERNOON. MODEL QPF
FIELDS ARE INDICATING THAT HEAVY RAINFALL WILL BE
POSSIBLE...ESPECIALLY OVER THE MOUNTAINS AND LOCATIONS OVER THE
PALMER DIVIDE. FLASH FLOODING WILL BE POSSIBLE ON AREA BURN SCARS
AND FLOOD PRONE AREAS FRIDAY AFTERNOON AND EVENING. SOME STORMS
ACROSS THE PLAINS COULD BECOME STRONG...WITH SMALL HAIL AND GUSTY
OUTFLOW WINDS ALSO POSSIBLE. MODELS IN GOOD AGREEMENT WITH
THUNDERSTORMS SHIFTING EAST ACROSS THE PLAINS FRIDAY NIGHT WITH
ALL ACTIVITY EXITING INTO KANSAS BY SATURDAY MORNING.
SATURDAY WILL LIKELY BE A PRETTY QUIET DAY ACROSS SOUTHERN
COLORADO GIVEN SUBSIDENCE BEHIND THE DEPARTING UPPER SYSTEM. A
COUPLE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS WILL
REMAIN POSSIBLE OVER THE MOUNTAINS...BUT COVERAGE LOOKS TO BE
MINIMAL.
A BROAD TROUGH WILL PERSIST OVER THE WESTERN CONUS THROUGH THE
MIDDLE OF NEXT WEEK WITH A COUPLE OF MORE DISTURBANCES MOVING
ACROSS SOUTHERN COLORADO. THE NEXT ONE LOOKS TO MOVE ACROSS THE
REGION ON SUNDAY. THIS WILL BRING ANOTHER UPTICK IN SHOWER AND
THUNDERSTORM ACTIVITY ACROSS THE STATE...WITH ACTIVITY STARTING
OVER THE MOUNTAINS LATE SUNDAY MORNING AND SPREADING EAST THROUGH
THE AFTERNOON AND EVENING. IN ADDITION...A COLD FRONT WILL MOVE
SOUTH ACROSS THE PLAINS DURING THE AFTERNOON...TURNING LOW LEVEL
FLOW UPSLOPE...WHICH WILL LIKELY AID PRECIPITATION DEVELOPMENT
ACROSS THE PLAINS SUNDAY AFTERNOON AND EVENING.
MODELS A BIT DIFFERENT ON THE ARRIVAL OF THE NEXT DISTURBANCE
DROPPING ACROSS THE ROCKIES...WITH GFS HAS BEEN BRINGING IT
THROUGH MONDAY EVENING...WITH THE ECMWF IS A BIT SLOWER ON
TUESDAY. THIS WILL LIKELY LEAD TO ANOTHER ROUND OF DECENT
PRECIPITATION FOR THE MOUNTAINS...AND SPREADING EAST INTO THE
PLAINS SOMETIME IN THE MONDAY TO TUESDAY TIME FRAME. THIS SYSTEM
LOOKS TO BE ACCOMPANIED BY A STRONG COLD FRONT WHICH SHOULD HELP
THE PLAINS SEE ANOTHER SHOT FOR PRECIPITATION. MOZLEY
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 238 PM MDT WED AUG 20 2014
VFR CONDITIONS ARE EXPECTED AT KCOS...KPUB AND KALS TONIGHT THROUGH
THURSDAY AFTERNOON. SOME THUNDERSTORMS WILL BE POSSIBLE IN THE
VCNTY OF KCOS EARLY THIS EVENING...BUT MAY NOT MAKE IT INTO THE
VCNTY OF KPUB AND KALS. THE MAIN THREATS WITH TSTMS WILL BE GUSTY
WINDS. ON THURSDAY AFTERNOON SOME TSTMS ARE EXPECTED OVR THE HYR
TRRN AND ONE OR TWO COULD MAKE IT INTO THE VCNTY OF KCOS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...28
LONG TERM...MOZLEY
AVIATION...28
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
303 PM MDT WED AUG 20 2014
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 158 PM MDT WED AUG 20 2014
MIDLEVEL QUASIGEOSTROPHIC SUBSIDENCE /FROM RAP ANALYSES/ AND
STABILITY /ACARS DATA/ IS KIND OF KEEPING CONVECTION AT BAY AS OF
20Z. THERE ARE A FEW ECHOES ON THE RADAR BUT THEY ARE RATHER WEAK
AND SHORT-LIVED AT THIS TIME. THERE IS ALSO A VERY LOCALIZED AREA
OF DOWNSLOPE FLOW OVER BOULDER COUNTY WHICH HAS LOWERED DEWPOINTS
AND GPS-MEASURED PRECIPITABLE WATER VALUES THERE AND PRETTY MUCH
SQUELCHED THE CONVECTION ALTOGETHER. THE HRRR HAS BEEN A BIT
OVERZEALOUS WITH CONVECTION THAT IS SUPPOSED TO BE ONGOING AT THIS
TIME AND INSISTS ON GENERATING QUITE A BIT OF ACTIVITY INTO THE
EVENING HOURS OF THE PLAINS. THE GFS QPF FIELDS SUGGEST THE SAME
THING WITH THE NAM AND ECMWF SEEMING A BIT MORE IN TOUCH WITH
REALITY. IT SEEMS PRUDENT TO HOLD ONTO LOW POPS IN ALL AREAS THIS
EVENING. TOMORROW DOES NOT APPEAR TO BE MUCH DIFFERENT THAN
TODAY. QUASIGEOSTROPHIC FORECAST DIAGNOSTICS CONTINUE TO FORECAST
SUBSIDENCE AND MODEL SOUNDINGS HAVE THE MIDLEVEL INSTABILITY LIKE
TODAY. CONSEQUENTLY NOT EXPECTING ANY MORE CONVECTION THAT WHAT
IS AROUND TODAY WITH THE PLAINS PERHAPS NOT SEEING ANYTHING.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 158 PM MDT WED AUG 20 2014
PRETTY GOOD MODEL AGREEMENT THROUGH THIS PERIOD...SHORTWAVES LIFT
OUT OF THE MEAN TROUGH OVER THE WEST PASSING OVER COLORADO ON
FRIDAY AND SUNDAY. A BIT MORE DISCREPANCY BY THE MIDDLE OF NEXT
WEEK WITH THE PROSPECTS FOR THE TROUGH SHIFTING EAST...OR JUST
ANOTHER SHORTWAVE MOVING AROUND IT.
FOR THE FRIDAY WAVE...WE WILL BE FIGHTING THE SAME ISSUES WE HAVE
HAD WITH SEVERAL OF THESE MOISTURE SURGES. WARM ADVECTION ALOFT
WILL LIMIT INSTABILITY WHILE THE LOW LEVELS DO NOT MOISTEN
MUCH...AND BY THE TIME THE BEST LIFT ARRIVES THERE IS EVEN A
LITTLE COOLING AT THE SURFACE. STILL EXPECTING INCREASED SHOWER
COVERAGE BUT MAINLY DUE TO LIFT IN THE ELEVATED MOIST LAYER. THIS
CURRENTLY APPEARS TO BE PLAYED WELL WITH SCATTERED SHOWERS AND
STORMS MAINLY FRIDAY AFTERNOON AND EVENING. I DID ADD A BIT MORE
SHOWER ACTIVITY THURSDAY NIGHT AS SOME MODEL RUNS SHOW SOME
CONVECTION MOVING OFF THE SOUTHERN COLORADO MOUNTAINS AND
PERSISTING OVERNIGHT. ALSO SLOWED DOWN THE END OF THE SHOWERS
EARLY SATURDAY IN LINE WITH MODEL TRENDS.
FOR THE WEEKEND...DRIER AIR SHOULD TAKE AWAY THE INSTABILITY SO
EXPECTING FAIRLY QUIET DAYS...STILL A LITTLE DIURNAL CONVECTION
AND SOME LIFT FROM THE SECOND WAVE SUNDAY SHOULD HELP...BUT A
RATHER UNFAVORABLE ENVIRONMENT.
FOR EARLY NEXT WEEK...THERE APPEARS TO BE A WEAK FRONT DROPPING
DOWN THE PLAINS IN THE MONDAY/TUESDAY TIME PERIOD RELATED TO SOME
DEEPENING OF THE UPSTREAM TROUGH. THIS COULD BRING INCREASED LOW
LEVEL MOISTURE...BUT ALSO SOME LOW LEVEL COOLING. SO ONCE AGAIN A
TRADEOFF THAT RESULTS IN SOME INCREASED COVERAGE...BUT NOT
NECESSARILY A LOT OF RAIN. THERE COULD BE AN OPTIMAL TIME ON
TUESDAY OR WEDNESDAY IF THE TROUGH AXIS DOES SHIFT EASTWARD WHERE
THERE IS A COMBINATION OF LIFT AND INSTABILITY. GFS WOULD SUGGEST
DRYING BEHIND THE TROUGH BY WEDNESDAY...WHILE THE ECMWF HOLDING
THE LONGWAVE TROUGH WEST OF US WOULD INDICATE NO COOLING ALOFT.
SO OVERALL MINOR VARIATIONS ON AN ENVIRONMENT WHICH IS ONLY
SLIGHTLY UNSTABLE IN THE AFTERNOONS...BUT IN THE MOIST PERIODS
COULD ALLOW SOME WEAK CONVECTION WHENEVER THERE IS FORCING. BLEND
OF THE MODEL CONSENSUS WITH THE PREVIOUS FORECAST LOOKS GOOD...I
DID RAISE POPS A LITTLE ON TUESDAY AND WEDNESDAY ON THE PLAINS IN
LINE WITH OUR NEIGHBORING OFFICES...WITH GREATER MOISTURE OUT
THERE THAT SEEMS REASONABLE.
&&
.AVIATION...(FOR THE TAFS THROUGH 00Z THURSDAY LATE AFTERNOON)
ISSUED AT 158 PM MDT WED AUG 20 2014
IF PRESENT CONDITIONS CONTINUE IT LOOKS LIKE KAPA WOULD HAVE THE
BEST /ALBEIT SMALL/ CHANCE OF SEEING SOME THUNDER THIS EVENING.
THE 19Z HRRR MODEL IS STILL INSISTING ON CREATING A LOT OF
THUNDERSTORM ACTIVITY WHICH IS LOOKING LESS AND LESS LIKELY AT
THIS POINT. THUS KBJC AND KDEN MAY MAKE IT THROUGH THE EVENING
WITHOUT ANY THUNDER. KBJC SHOULD SEE DOWNSLOPE FLOW/DRAINAGE WINDS
THROUGH TONIGHT WITH SPEEDS IN THE 8-15KT RANGE. KAPA AND KDEN
WILL HAVE LIGHTER WINDS THROUGHOUT THE PERIOD WITH DRAINAGE FLOW
KICKING IN AFTER DARK.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...ET
LONG TERM...GIMMESTAD
AVIATION...ET
AREA FORECAST DISCUSSION
NWS TAUNTON MA
703 PM EDT WED AUG 20 2014
.SYNOPSIS...
WET WEATHER LIKELY IMPACTING WESTERN AND CENTRAL PORTIONS OF NEW
ENGLAND BEGINNING TONIGHT AND CONTINUING THROUGH FRIDAY. DRIER AND
COOLER WEATHER FOLLOWS INTO THE WEEKEND. A WARM-UP IS POSSIBLE
INTO NEXT WEEK PRIOR TO AN UNSETTLED PATTERN AHEAD OF A FRONTAL
BOUNDARY SWEEPING SOUTH OUT OF CANADA.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
7 PM UPDATE...
DIURNAL CU DISSIPATING IN EASTERN NEW ENG...BUT EXPECT AN
EXPANSION OF SC IN THE WEST TONIGHT AS LOW LEVEL MOISTURE
INCREASES FROM THE WEST. ALSO MONITORING LOW CLOUDS SE OF ACK
WHICH IS EXPECTED TO MOVE ACROSS THE ISLANDS AND OUTER CAPE
OVERNIGHT. STILL UNCERTAINTY AS TO HOW FAR NORTH AND WEST OCEAN
SHOWERS WILL GET ASSOCD WITH AREA OF CONVERGENCE OF HIGHER THETAE
AIR. 18Z NAM/GFS HAVE BACKED OFF AND SO WE LOWERED POPS TO CHC
CATEGORY FOR OUTER CAPE AND ACK AS THIS IS A LOW CONFIDENCE
FORECAST.
PREVIOUS DISCUSSION...
HEIGHTS FALL AS THE GREAT LAKES LOW SHIFTS INTO THE NE CONUS...
TROUGHING TOWARDS THE W-E AXIS OF LOW PRESSURE AND INSTABILITY OFF
THE MID-ATLANTIC. LABRADOR RIDGE OF HIGH PRESSURE ALONG WITH DRY
AIR AND SUBSIDENCE WILL PERSIST INTO NEW ENGLAND...AHEAD OF WHICH
THE COLLISION TOWARDS LOW PRESSURE AND HIGHER THETA-E AIR WILL
RESULT IN A DEFINED AREA OF CONVERGENCE ACROSS PA/NY...AND
POSSIBLY SE MA.
TO THE W...INCREASING THETA-E MOISTURE LOADING THE MID- TO UPPER-
LEVELS WILL LIKELY RESULT IN INCREASING AND THICKENING CLOUDS W TO
E. BUT STILL A LOT OF DRY AIR TO OVERCOME BELOW H6-7 ESPECIALLY OVER
E NEW ENGLAND WITH THE INVERTED RIDGE. NOTING THE WARM FRONT WELL W
ACROSS PA/NY ALONG WITH PARENT DYNAMICS AND LOW-LEVEL CONVERGENCE...
BEST CHANCES FOR SHOWERS WITHIN AREAS OF DEEP-LAYER ASCENT SHOULD
BE NO FURTHER E OF THE CT-RIVER VALLEY. EXPECTING SPRINKLES. ITS
LIKELY BETTER ACTIVITY WILL BE WELL N/W PARENT WITH BETTER MOISTURE
CONVERGENT ALONG THE NOSE OF THE H925-85 JET INTO THE ADIRONDACKS
ON UP INTO ONTARIO/QUEBEC AS DESTABILIZATION CONCLUDES. PREFER
CHANCE POPS ONLY INTO THE CT-VALLEY.
TO THE SE...TROUGHING SE BACKS LOW PRESSURE AND HIGHER THETA-E AIR
OFF THE E-W STALLED FRONT OFF THE MID-ATLANTIC. THE CONVERGENCE OF
AIR MASSES ALONG AN INVERTED-TROUGH TO THE AFOREMENTIONED LOW WILL
BE THE FOCUS FOR POTENTIAL HEAVY RAIN...EVEN THUNDERSTORMS. MAINLY A
WARM-RAIN PROCESS WITH PWATS UP TO 1.75 INCHES. WHILE A CONSISTENT
SIGNAL AMONG FORECAST SOLUTIONS...OUTCOMES VARY SLIGHTLY LIKELY DUE
TO THE STRENGTH OF INVERTED-RIDGE. WILL GO WITH LIKELY POPS FOR
NANTUCKET WITH CHANCE POPS INTO THE CAPE AND SE MA. THE SETUP IS
ALREADY COMING TOGETHER SEEN PER IR/VISIBLE SATELLITE...BUT A LOT
OF UNCERTAINTY BETWEEN THE STRENGTH OF THE RIDGE AND THE ZONE
SETUP OF CONVERGENCE. WRF/NAM THE MOST ROBUST WITH OUTCOMES. 17Z
HRRR/18Z RAP HAS ACTIVITY MISSING NANTUCKET. NOT ENOUGH CONFIDENCE
TO GO HIGH CATEGORICAL POPS.
THICKER CLOUDS ACROSS THE REGION WILL LIMIT RADIATIONAL COOLING.
ANTICIPATING A MORE MILD NIGHT OVER MUCH OF THE REGION WITH LOWS
AROUND THE UPPER-50S. COOLEST CONDITIONS EXPECTED ACROSS E/SE MA
UNDER LIGHT AND VARIABLE WINDS AND THE BETTER CHANCE OF RADIATING
OUT...LOWS AROUND THE MID-50S. FOR SUCH AREAS THERE IS ALSO THE
POSSIBILITY OF PATCHY GROUND FOG.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
THURSDAY INTO THURSDAY NIGHT...
CLOSED LOW OUT OF THE GREAT LAKES GRADUALLY WOBBLES INTO NEW ENGLAND
THROUGH THE FORECAST PERIOD. THE SYSTEM WEAKENS AS IT TRANSITIONS SW
RE-EMERGING ALONG THE W-E FRONTAL BOUNDARY OFF THE MID-ATLANTIC
TOWARDS THE BETTER THERMAL-INSTABILITY AXIS.
SUBSEQUENT RISING HEIGHTS ALLOWS RIDGING TO BUILD SW THURSDAY
NIGHT. WHILE HIGHER THETA-E AIR STREAMS ACROSS THE REGION WITHIN
THE MID-LEVELS...E-FLOW WITHIN LOW-LEVELS FROM THE LABRADOR HIGH
UNDERCUTS MOISTURE LOADING ALOFT KEEPING CONDITIONS FAIRLY STABLE
AND DRY...LIKELY TO ERODE ACTIVITY S AND W.
AS THE LOW TRANSITIONS AND WEAKENS...PRECIPITATION ACROSS THE CAPE
AND ISLANDS CONCLUDES WITH THE STRENGTHENING INFLUENCE OF THE
RIDGE. ENERGY AND MOISTURE PARENT TO THE LOW IS ANTICIPATED TO
SWEEP MAINLY ACROSS SW NEW ENGLAND...PERHAPS SW OF A LINE FROM
BOSTON TO KEENE NH. WILL KEEP THESE AREAS UNDER CHANCE POPS
ACCORDINGLY WITH ASCENT AND LIKELY CONVERGENCE AGAINST THE SW
BUILDING RIDGE.
WITH THE UNDERCUTTING DRY AND STABLE AIRMASS OFF THE OCEAN WITH THE
STRENGTHENING RIDGE LATE...AND CLOUDS THROUGH THE PERIOD LIMITING
DESTABILIZATION...NOT EXPECTING ANY THUNDER. HIGHS AROUND THE MID-
TO UPPER-70S DURING THE DAY WITH LOWS AROUND THE UPPER-50S.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
HIGHLIGHTS...
* QUIET WEATHER EXPECTED THROUGH MUCH OF THE LONG TERM
* UNCERTAINTY INCREASES MIDDLE OF NEXT WEEK WITH AN APPROACHING
FRONT.
MODELS ARE IN GOOD AGREEMENT THROUGH MUCH OF THE LONG TERM. A
PERSISTENT UPPER LEVEL TROUGH OVER THE NORTHEAST WILL SLOWLY MAKE
ITS WAY EAST...MOVING JUST OFFSHORE THIS WEEKEND AS AN UPPER LEVEL
RIDGE TRIES TO PUSH NORTHEASTWARD FROM THE SOUTHERN U.S. THE UPPER
TROUGH IS RATHER PERSISTENT THOUGH AND EACH MODEL RUN KEEPS THE
TROUGH JUST OFFSHORE LONGER AND LONGER.
COOLER...LESS SEASONABLE WEATHER IS EXPECTED WHILE HIGH PRESSURE IN
QUEBEC WILL KEEP THINGS RELATIVELY DRY. MODELS ARE INDICATING SOME
POTENTIAL FOR QPF EACH DAY THROUGH THE WEEKEND BUT GIVEN THE LACK OF
ANY FORCING MECHANISM AND VERY LITTLE MOISTURE TO SPEAK OF...
THINKING THIS COULD BE CONVECTIVE FEEDBACK RATHER THAN A DEPICTION
OF ANYTHING LIKELY TO OCCUR.
THE HIGH WILL SINK SOUTH THROUGH THE WEEKEND INTO EARLY NEXT
WEEK...EVENTUALLY DROPPING SOUTH AND EAST OF SOUTHERN NEW ENGLAND
AND RETURNING US TO A MORE WESTERLY FLOW. LOW PRESSURE IN ONTARIO
MAY EVENTUALLY MOVE EASTWARD INTO QUEBEC BRINGING A COLD FRONT
THROUGH SOUTHERN NEW ENGLAND WEDNESDAY OR THURSDAY. THIS IS WHERE
MODELS START TO DIVERGE A BIT WITH THE ECMWF A BIT QUICKER THAN THE
GFS WITH THE APPROACH OF THE FRONT. DEPENDING ON AVAILABLE MOISTURE
THIS MAY INITIATE A FEW SHOWERS AND THUNDERSTORMS AHEAD OF THE FRONT.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT TERM...THROUGH THURSDAY NIGHT...MODERATE CONFIDENCE.
VFR. LIGHT/VRB WINDS OVERNIGHT BEFORE PREVAILING E/SE THURSDAY
INTO THURSDAY NIGHT. LOW-END VFR CIGS SLOWLY BUILDING E ALONG WITH
-RA CHANCES TOWARDS IJD-ORH-AFN. WILL ALSO NEED TO WATCH SE MA FOR
POTENTIAL +RA AND MVFR-IFR IMPACTS BEGINNING AFTER MIDNIGHT INTO
THU MORNING. CONDITIONS BEGIN TO IMPROVE CLOSER TO FRIDAY
MORNING.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. E/SE FLOW PREVAILS. EXPECT
CONDITIONS NO LOWER THAN LOW-END VFR CIGS. -RA CHANCES MINIMAL.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF. -RA CHANCES BEGIN TOWARDS
THURSDAY MORNING ALONG WITH LOW-END VFR CIGS. MVFR CIGS POSSIBLE
THOUGH LOW-CONFIDENCE AT THIS TIME.
OUTLOOK...FRIDAY THROUGH MONDAY...
MODERATE CONFIDENCE. MAINLY VFR. LOW PROBABILITY OF PATCHY
MVFR/IFR FOG EACH NIGHT.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT-TERM...THROUGH THURSDAY NIGHT...MODERATE CONFIDENCE.
CLOSELY MONITORING THE SE WATERS. MAY SEE A SURGANCE OF RAIN ALONG
WITH VISIBILITY IMPACTS DURING THE OVERNIGHT HOURS INTO THURSDAY
ALONG WITH AN INCREASE IN E-NE FLOW AS AN AREA OF LOW PRESSURE
DEVELOPS WELL OUT TO SEA. QUITE POSSIBLE WIND GUST UP TO 25
KTS...BUT WILL HOLD AROUND 20 KTS FOR NOW. WILL KEEP SEAS AROUND 3
TO 4 FEET. CONDITIONS RELAX INTO FRIDAY MORNING.
OUTLOOK...FRIDAY THROUGH MONDAY...
MODERATE TO HIGH CONFIDENCE. QUIET BOATING WEATHER IS EXPECTED
THROUGH MUCH OF THE PERIOD WITH HIGH PRESSURE ACROSS THE REGION.
LOW PROBABILITY OF PATCHY OVERNIGHT FOG LIMITING VISIBILITIES.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...RLG/SIPPRELL
NEAR TERM...KJC/SIPPRELL
SHORT TERM...SIPPRELL
LONG TERM...RLG
AVIATION...KJC/RLG/SIPPRELL
MARINE...RLG/SIPPRELL
AREA FORECAST DISCUSSION
NWS TAUNTON MA
409 PM EDT WED AUG 20 2014
.SYNOPSIS...
WET WEATHER LIKELY IMPACTING WESTERN AND CENTRAL PORTIONS OF NEW
ENGLAND BEGINNING TONIGHT AND CONTINUING THROUGH FRIDAY. DRIER AND
COOLER WEATHER FOLLOWS INTO THE WEEKEND. A WARM-UP IS POSSIBLE
INTO NEXT WEEK PRIOR TO AN UNSETTLED PATTERN AHEAD OF A FRONTAL
BOUNDARY SWEEPING SOUTH OUT OF CANADA.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
INTO THIS EVENING...
DIURNAL CUMULUS WILL DISSIPATE WITH THE CONCLUSION OF DAYTIME
MIXING. HIGH CLOUDS WILL LIKELY BEGIN TO FILTER INTO THE REGION
FROM THE CONVECTION ONGOING OVER NY/PA. ALSO MONITORING THE AREA
SE OF NANTUCKET WHERE LOW-LEVEL CONVERGENCE OF HIGHER THETA-E AIR
IS LIKELY ONGOING LENDING TO SOME LOW CLOUDS. EXPECT THIS ACTIVITY
TO FILTER ACROSS THE ISLAND TOWARDS THE CAPE AS WE GO INTO THE
EVENING HOURS. WILL SEE WINDS BECOME LIGHT AND VARIABLE.
TONIGHT...
HEIGHTS FALL AS THE GREAT LAKES LOW SHIFTS INTO THE NE CONUS...
TROUGHING TOWARDS THE W-E AXIS OF LOW PRESSURE AND INSTABILITY
OFF THE MID-ATLANTIC. LABRADOR RIDGE OF HIGH PRESSURE ALONG WITH
DRY AIR AND SUBSIDENCE WILL PERSIST INTO NEW ENGLAND...AHEAD OF
WHICH THE COLLISION TOWARDS LOW PRESSURE AND HIGHER THETA-E AIR
WILL RESULT IN A DEFINED AREA OF CONVERGENCE ACROSS PA/NY...AND
POSSIBLY SE MA.
TO THE W...INCREASING THETA-E MOISTURE LOADING THE MID- TO UPPER-
LEVELS WILL LIKELY RESULT IN INCREASING AND THICKENING CLOUDS W TO
E. BUT STILL A LOT OF DRY AIR TO OVERCOME BELOW H6-7 ESPECIALLY OVER
E NEW ENGLAND WITH THE INVERTED RIDGE. NOTING THE WARM FRONT WELL W
ACROSS PA/NY ALONG WITH PARENT DYNAMICS AND LOW-LEVEL CONVERGENCE...
BEST CHANCES FOR SHOWERS WITHIN AREAS OF DEEP-LAYER ASCENT SHOULD
BE NO FURTHER E OF THE CT-RIVER VALLEY. EXPECTING SPRINKLES. ITS
LIKELY BETTER ACTIVITY WILL BE WELL N/W PARENT WITH BETTER MOISTURE
CONVERGENT ALONG THE NOSE OF THE H925-85 JET INTO THE ADIRONDACKS
ON UP INTO ONTARIO/QUEBEC AS DESTABILIZATION CONCLUDES. PREFER
CHANCE POPS ONLY INTO THE CT-VALLEY.
TO THE SE...TROUGHING SE BACKS LOW PRESSURE AND HIGHER THETA-E AIR
OFF THE E-W STALLED FRONT OFF THE MID-ATLANTIC. THE CONVERGENCE OF
AIR MASSES ALONG AN INVERTED-TROUGH TO THE AFOREMENTIONED LOW WILL
BE THE FOCUS FOR POTENTIAL HEAVY RAIN...EVEN THUNDERSTORMS. MAINLY A
WARM-RAIN PROCESS WITH PWATS UP TO 1.75 INCHES. WHILE A CONSISTENT
SIGNAL AMONG FORECAST SOLUTIONS...OUTCOMES VARY SLIGHTLY LIKELY DUE
TO THE STRENGTH OF INVERTED-RIDGE. WILL GO WITH LIKELY POPS FOR
NANTUCKET WITH CHANCE POPS INTO THE CAPE AND SE MA. SLIGHT CHANCE
OF THUNDER WITH AT LEAST A LITTLE INSTABILITY PRESENT. THE SETUP
IS ALREADY COMING TOGETHER SEEN PER IR/VISIBLE SATELLITE...BUT A
LOT OF UNCERTAINTY BETWEEN THE STRENGTH OF THE RIDGE AND THE ZONE
SETUP OF CONVERGENCE. WRF/NAM THE MOST ROBUST WITH OUTCOMES. 17Z
HRRR/18Z RAP HAS ACTIVITY MISSING NANTUCKET. NOT ENOUGH CONFIDENCE
TO GO HIGH CATEGORICAL POPS.
THICKER CLOUDS ACROSS THE REGION WILL LIMIT RADIATIONAL COOLING.
ANTICIPATING A MORE MILD NIGHT OVER MUCH OF THE REGION WITH LOWS
AROUND THE UPPER-50S. COOLEST CONDITIONS EXPECTED ACROSS E/SE MA
UNDER LIGHT AND VARIABLE WINDS AND THE BETTER CHANCE OF RADIATING
OUT...LOWS AROUND THE MID-50S. FOR SUCH AREAS THERE IS ALSO THE
POSSIBILITY OF PATCHY GROUND FOG.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
THURSDAY INTO THURSDAY NIGHT...
CLOSED LOW OUT OF THE GREAT LAKES GRADUALLY WOBBLES INTO NEW ENGLAND
THROUGH THE FORECAST PERIOD. THE SYSTEM WEAKENS AS IT TRANSITIONS SW
RE-EMERGING ALONG THE W-E FRONTAL BOUNDARY OFF THE MID-ATLANTIC
TOWARDS THE BETTER THERMAL-INSTABILITY AXIS.
SUBSEQUENT RISING HEIGHTS ALLOWS RIDGING TO BUILD SW THURSDAY
NIGHT. WHILE HIGHER THETA-E AIR STREAMS ACROSS THE REGION WITHIN
THE MID-LEVELS...E-FLOW WITHIN LOW-LEVELS FROM THE LABRADOR HIGH
UNDERCUTS MOISTURE LOADING ALOFT KEEPING CONDITIONS FAIRLY STABLE
AND DRY...LIKELY TO ERODE ACTIVITY S AND W.
AS THE LOW TRANSITIONS AND WEAKENS...PRECIPITATION ACROSS THE CAPE
AND ISLANDS CONCLUDES WITH THE STRENGTHENING INFLUENCE OF THE
RIDGE. ENERGY AND MOISTURE PARENT TO THE LOW IS ANTICIPATED TO
SWEEP MAINLY ACROSS SW NEW ENGLAND...PERHAPS SW OF A LINE FROM
BOSTON TO KEENE NH. WILL KEEP THESE AREAS UNDER CHANCE POPS
ACCORDINGLY WITH ASCENT AND LIKELY CONVERGENCE AGAINST THE SW
BUILDING RIDGE.
WITH THE UNDERCUTTING DRY AND STABLE AIRMASS OFF THE OCEAN WITH THE
STRENGTHENING RIDGE LATE...AND CLOUDS THROUGH THE PERIOD LIMITING
DESTABILIZATION...NOT EXPECTING ANY THUNDER. HIGHS AROUND THE MID-
TO UPPER-70S DURING THE DAY WITH LOWS AROUND THE UPPER-50S.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
HIGHLIGHTS...
* QUIET WEATHER EXPECTED THROUGH MUCH OF THE LONG TERM
* UNCERTAINTY INCREASES MIDDLE OF NEXT WEEK WITH AN APPROACHING
FRONT.
MODELS ARE IN GOOD AGREEMENT THROUGH MUCH OF THE LONG TERM. A
PERSISTENT UPPER LEVEL TROUGH OVER THE NORTHEAST WILL SLOWLY MAKE
ITS WAY EAST...MOVING JUST OFFSHORE THIS WEEKEND AS AN UPPER LEVEL
RIDGE TRIES TO PUSH NORTHEASTWARD FROM THE SOUTHERN U.S. THE UPPER
TROUGH IS RATHER PERSISTENT THOUGH AND EACH MODEL RUN KEEPS THE
TROUGH JUST OFFSHORE LONGER AND LONGER.
COOLER...LESS SEASONABLE WEATHER IS EXPECTED WHILE HIGH PRESSURE IN
QUEBEC WILL KEEP THINGS RELATIVELY DRY. MODELS ARE INDICATING SOME
POTENTIAL FOR QPF EACH DAY THROUGH THE WEEKEND BUT GIVEN THE LACK OF
ANY FORCING MECHANISM AND VERY LITTLE MOISTURE TO SPEAK OF...
THINKING THIS COULD BE CONVECTIVE FEEDBACK RATHER THAN A DEPICTION
OF ANYTHING LIKELY TO OCCUR.
THE HIGH WILL SINK SOUTH THROUGH THE WEEKEND INTO EARLY NEXT
WEEK...EVENTUALLY DROPPING SOUTH AND EAST OF SOUTHERN NEW ENGLAND
AND RETURNING US TO A MORE WESTERLY FLOW. LOW PRESSURE IN ONTARIO
MAY EVENTUALLY MOVE EASTWARD INTO QUEBEC BRINGING A COLD FRONT
THROUGH SOUTHERN NEW ENGLAND WEDNESDAY OR THURSDAY. THIS IS WHERE
MODELS START TO DIVERGE A BIT WITH THE ECMWF A BIT QUICKER THAN THE
GFS WITH THE APPROACH OF THE FRONT. DEPENDING ON AVAILABLE MOISTURE
THIS MAY INITIATE A FEW SHOWERS AND THUNDERSTORMS AHEAD OF THE FRONT.
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT TERM...THROUGH THURSDAY NIGHT...MODERATE CONFIDENCE.
VFR. SEA-BREEZES CONTINUE...BECOMING LIGHT/VRB OVERNIGHT BEFORE
PREVAILING E/SE THURSDAY INTO THURSDAY NIGHT. LOW-END VFR CIGS
SLOWLY BUILDING E ALONG WITH -RA CHANCES TOWARDS IJD-ORH-AFN. WILL
ALSO NEED TO WATCH SE MA FOR POTENTIAL +RA AND MVFR-IFR IMPACTS
BEGINNING AFTER MIDNIGHT THURSDAY. CONDITIONS BEGIN TO IMPROVE
CLOSER TO FRIDAY MORNING.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. E/SE FLOW PREVAILS. EXPECT
CONDITIONS NO LOWER THAN LOW-END VFR CIGS. -RA CHANCES MINIMAL.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF. -RA CHANCES BEGIN TOWARDS
THURSDAY MORNING ALONG WITH LOW-END VFR CIGS. MVFR CIGS POSSIBLE
THOUGH LOW-CONFIDENCE AT THIS TIME.
OUTLOOK...FRIDAY THROUGH MONDAY...
MODERATE CONFIDENCE. MAINLY VFR. LOW PROBABILITY OF PATCHY
MVFR/IFR FOG EACH NIGHT.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT-TERM...THROUGH THURSDAY NIGHT...MODERATE CONFIDENCE.
CLOSELY MONITORING THE SE WATERS. MAY SEE A SURGANCE OF RAIN ALONG
WITH VISIBILITY IMPACTS DURING THE OVERNIGHT HOURS INTO THURSDAY
ALONG WITH AN INCREASE IN E-NE FLOW AS AN AREA OF LOW PRESSURE
DEVELOPS WELL OUT TO SEA. QUITE POSSIBLE WIND GUST UP TO 25
KTS...BUT WILL HOLD AROUND 20 KTS FOR NOW. WILL KEEP SEAS AROUND 3
TO 4 FEET. CONDITIONS RELAX INTO FRIDAY MORNING.
OUTLOOK...FRIDAY THROUGH MONDAY...
MODERATE TO HIGH CONFIDENCE. QUIET BOATING WEATHER IS EXPECTED
THROUGH MUCH OF THE PERIOD WITH HIGH PRESSURE ACROSS THE REGION.
LOW PROBABILITY OF PATCHY OVERNIGHT FOG LIMITING VISIBILITIES.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...RLG/SIPPRELL
NEAR TERM...SIPPRELL
SHORT TERM...SIPPRELL
LONG TERM...RLG
AVIATION...RLG/SIPPRELL
MARINE...RLG/SIPPRELL
AREA FORECAST DISCUSSION
NWS DES MOINES IA
339 PM CDT WED AUG 20 2014
.SHORT TERM /TONIGHT/...
ISSUED AT 340 PM CDT WED AUG 20 2014
TONIGHTS FORECAST IS QUITE DIFFICULT AND THE MODELS ARE NOT MUCH
HELP. A WARM FRONT ACROSS IOWA STRETCHES FROM A LOW OVER WEST
CENTRAL SOUTH DAKOTA. THETA-E ADVECTION AND SOME MODEST INSTABILITY
KEPT THUNDERSTORMS FESTERING AHEAD OF THE FRONTAL BOUNDARY ALL DAY
LONG AND SHEAR ACTUALLY INCREASED THROUGH THE AFTERNOON HOURS. THE
MODELS CONTINUE THE SHOWERS/STORMS ALONG AND AHEAD OF THE FRONTAL
BOUNDARY IN A ZONE OF WARM ADVECTION THROUGH THE AFTERNOON HOURS
INTO EARLY EVENING. THE HRRR AND HOPWRF THEN SQUELCH THE PRECIP IN
IOWA OVERNIGHT WHILE THE NAM CONTINUES TO DEVELOP STORMS ACROSS
NORTH CENTRAL/NORTHEAST IOWA...ESPECIALLY WITH A LOW LEVEL JET THAT
INTENSIFIES LATER THIS EVENING. IT IS VERY HARD TO SAY WHERE THAT
BOUNDARY WILL LIFT TO THIS EVENING...OR WILL IT REMAIN FAIRLY
STATIONARY. I AM REASONABLY CERTAIN THAT WE WILL NOT BE DRY ACROSS
THE NORTH BUT I AM SKEPTICAL ABOUT KEEPING 60-70 POPS IN THAT AREA
GIVEN THE TRENDS FOR THE PRECIP TO SLOWLY LIFT NORTH.
THE MAIN ADJUSTMENTS TO THE GOING FORECAST WERE TO LOWER POPS SOME
ACROSS THE NORTH AND MENTION HEAVY RAIN ACROSS A PART OF THE NORTH
CENTRAL AND NORTHEAST. HOWEVER...IF THE NAM12 IS CORRECT MY
FORECAST WILL NEED TO BE ADJUSTED ONCE THE LLJ COMES INTO PLAY AFTER
03Z OR SO AS HIGHER POPS WILL BE NEEDED FURTHER SOUTH. HEAVY
RAINFALL WILL ALSO BE MORE OF A CONCERN ACROSS AREAS NORTH OF
HIGHWAY 20.
.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
ISSUED AT 340 PM CDT WED AUG 20 2014
RELATIVELY ACTIVE CONDITIONS TO PERSIST FOR MUCH OF THE LONG TERM
WITH BROAD WSW FLOW ALOFT AND SURFACE BOUNDARY NEARBY. ANY ONGOING
CONVECTION ON THURSDAY MORNING SHOULD DISSIPATE WITH FORCING
WEAKENING. WARM SECTOR WILL BE IN PLACE WITH TEMPERATURES CLIMBING
NICELY THROUGH THE DAY. STILL MAY SEE SOME MID TO HIGH CLOUDS
OVERHEAD AND THIS MAY LIMIT DAYTIME HIGHS...HOWEVER STILL A VERY
WARM AND HUMID DAY EXPECTED FOR MOST LOCATIONS. SURFACE BOUNDARY
WILL EASE INTO NORTHERN IOWA ON THURSDAY NIGHT WITH SOME SCATTERED
CONVECTION EXPECTED ALONG THE FRONT OVERNIGHT. THESE STORMS ARE
EXPECTED TO WEAKEN OVERNIGHT TOWARD DAYBREAK AS INFLOW WEAKENS AND
COL REGION PUSHES INTO THE STATE. FRIDAY WILL SEE THE COL PASS
THROUGH IOWA WITH LIMITED CONVECTION CHANCES FOR MUCH OF THE DAY.
HOWEVER...A MORE VIGOROUS SHORTWAVE WILL EJECT INTO THE PLAINS
LATER FRIDAY WITH INCREASING FLOW INTO THE FRONT LATE FRIDAY INTO
FRIDAY NIGHT. MODELS HAVE ALL BEEN INDICATING RATHER ROBUST
CONVECTION BY LATE FRIDAY ACROSS THE PLAINS PUSHING INTO IOWA
OVERNIGHT. HAVE CONTINUED THE HIGHER POPS ON FRIDAY
NIGHT...ESPECIALLY ACROSS THE NORTHWEST WHERE THE BEST FORCING AND
INFLOW INTO SYSTEM IS ANTICIPATED. THE THREAT FOR CONVECTION WILL
PERSIST INTO THE WEEKEND AND EARLY NEXT WEEK AS THE FRONTAL
BOUNDARY REMAINS NEAR THE STATE. AT THIS POINT...IT APPEARS MUCH
OF THE CONVECTION THIS WEEKEND WILL BE NEAR NORTHERN IOWA WITH HOT
AND HUMID CONDITIONS IN THE SOUTH. THE BULK OF THE SYSTEM IS NOT
EXPECTED TO PASS THROUGH THE REGION UNTIL THE MIDDLE OF NEXT WEEK
WHEN GOOD COVERAGE OF STORMS IS ANTICIPATED TUESDAY NIGHT INTO
WEDNESDAY. TEMPERATURES WILL REMAIN VERY WARM TO HOT SOUTH OF THE
BOUNDARY DURING THIS TIME.
THE THREAT FOR HEAVY RAINFALL WILL BE EVER PRESENT WITH THIS
CONVECTION FOR MUCH OF THE FORECAST. PWAT VALUES WILL IN GENERAL
BE AT OR ABOVE 1.50" WITH CONVECTION EAST OR SOUTHEAST AND
TRAINING A POSSIBILITY FROM TIME TO TIME. WHILE WIDESPREAD
FLOODING IS NOT EXPECTED GIVEN MATURE VEGETATIVE
GROWTH...LOCALIZED FLOODING MAY OCCUR. THE PRIMARY FLASH FLOOD
THREAT WILL REMAIN IN URBAN AREAS. HOWEVER...IF SEVERAL NIGHTS OF
RAIN DO OCCUR IN THE SAME AREA...A MORE GENERALIZED FLASH FLOOD
THREAT MAY MATERIALIZE.
THE OTHER CONCERN WILL BE WITH HOT AND HUMID CONDITIONS SOUTH OF
THE BOUNDARY. HEAT INDEX VALUES ARE EXPECTED TO CLIMB ABOVE 100
DEGREES FROM TIME TO TIME AND MAY BECOME PROBLEMATIC...ESPECIALLY
IN SOUTHERN IOWA SHOULD SEVERAL DAY STRING TOGETHER OF HOT AND
STICKY CONDITIONS. MUCH WILL DEPEND ON THE EXTEND OF CONVECTION
AND WHERE OUTFLOW BOUNDARYS AND SUBSEQUENT CONVECTION END UP. AT
THIS POINT...GIVEN THE UNCERTAINTY...NO HEADLINES FOR HEAT WILL BE
ISSUED.
&&
.AVIATION...20/18Z
ISSUED AT 1248 PM CDT WED AUG 20 2014
SHOWERS AND THUNDERSTORMS PERSIST IN A ZONE OF INSTABILITY AHEAD OF
A WARM FRONT OVER SOUTHERN IOWA THAT EXTENDS BACK INTO SOUTH DAKOTA.
SHOWERS AND STORMS KEEP REDEVELOPING IN THIS ZONE EVEN BACK INTO
NEBRASKA AND WILL CONTINUE TO FESTER OVER TAF LOCATIONS FROM FOD TO
ALO AND MCW THROUGH 02Z. THERE MAY BE A SHORT BREAK THIS EVENING
BEFORE A STRONG PUSH OF MOISTURE SURGES INTO IOWA ON A STRONG LOW
LEVEL JET. ALONG AND NORTH OF THE FRONTAL BOUNDARY STORMS MAY
INTENSIFY PRODUCING HEAVY RAINFALL AND A FEW OF THE MORE ROBUST
STORMS MAY PRODUCE STRONG WIND AND HAIL. MVFR VSBYS WILL LARGELY
PREVAIL EITHER DUE TO FOG AND/OR HEAVY RAIN. CIGS WILL ALSO LOWER
IN THUNDERSTORMS.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...FAB
LONG TERM...COGIL
AVIATION...FAB
AREA FORECAST DISCUSSION
NWS TOPEKA KS
558 PM CDT Wed Aug 20 2014
...AVIATION UPDATE...
.SHORT TERM...(This Evening through Thursday)
Issued at 333 PM CDT WED AUG 20 2014
A broad upper level ridge axis will continue to amplify across the
lower and mid MS river valley over the next 24 hours.
A minor upper level trough was located across northeast OK and
southeast KS this afternoon, on the western edge of the H5 ridge
axis, and will move northeast across southeast KS into western MO
this afternoon through early this evening. A shower did pop up
across southern Coffey county but did dissipate. This minor H5
trough may provide just enough lift for an isolated shower or
thunderstorms along and southeast of I-35 through the late afternoon
and early evening hours. I will keep POPS at 14 percent due to the
very isolated coverage.
During the evening hours scattered thunderstorms will develop across
western KS and eastern CO. Most of the thunderstorms will lift
northeast into NE but the trailing edge of any thunderstorm complex
may move across portions of north central and northeast KS late
Tonight and through the mid morning hours of Thursday. At this time
any thunderstorm complex that develops across western KS Tonight
should be decaying through the early morning hours of Thursday, thus
the thunderstorms will not be severe as they move northeast into a
less favorable environment across northeast KS.
Thursday will be mostly sunny as the H5 ridge axis amplifies across
the southern and mid MS river valley. Thunderstorms should remain
well west and north of the CWA during the daylight hours. Highs will
warm into the mid to upper 90s once again. A few locations across
the southwestern counties of the CWA may reach the 100 degree mark.
Heat indices will warm into the 100 to 104 degree range during the
afternoon hours. Some isolated areas across east central KS may see
heat indices reach around 105 degrees.
.LONG TERM...(Thursday Night through Wednesday)
Issued at 333 PM CDT WED AUG 20 2014
The mid-level flow will remain fairly unchanged through the end of
the week into the weekend with a broad ridge remaining in place
across much of the central and eastern U.S. and a trough positioned
over the western U.S. Thursday night through Saturday the models are
in good agreement with the mid-level trough currently over the
Pacific Northwest digging southward along the western Rockies with
the ridge amplifying further northward toward the Great Lakes
region. This pattern will keep southwesterly flow aloft across the
region, which will continue to support warm air advection through
the end of the week and into the weekend with 850MB temperatures
reaching into the 23C-26C degree range. Hot and humid conditions are
expected during that period as temperatures become unseasonably warm
with highs reaching into the middle to upper 90s Friday and
Saturday. These high temperatures combined with dewpoints reaching
into the mid 60s to low 70s will result in afternoon heat indices
soaring into the 100F to 104F degree range Friday and near 100F
degrees on Saturday. We will continue to monitor these conditions
closely to see if a heat advisory is needed for Friday. During this
period, surface low pressure will become anchored across much of
the Northern and Central Plains with a fairly stationary front
situated near north central Kansas. There doesn`t appear to be much
in the way of forcing along this boundary, however there may be
scattered chances for precipitation from late week through the early
weekend, especially across north central and northern Kansas. At
this time, the better chances for precipitation look to be during
the evening and overnight hours as the low-level jet increases over
the region.
Saturday night and Sunday, models show a strong embedded shortwave
trough lifting northeastward across the northern Rockies and into
the Northern Plains. This advancing shortwave should be enough to
slowly push the stationary front eastward through the region Sunday
night and Monday, so have more widespread chance PoPs during that
period. This cold front may lift back northward across the area as a
warm front, however there is model uncertainty with regards to how
far north this warm front will lift, so confidence is low with
precipitation chances Monday night through Wednesday. At this time
have slight to low-end chance PoPs through that period.
The frontal passage Sunday night into Monday will cause winds to
shift to the north, providing a bit of relief to the heat with highs
dropping into the middle 80s to low 90s Monday. Temperatures are
more uncertain for Tuesday and Wednesday depending upon where the
warm front is located and whether or not the region is situated
within the warm sector, so have highs remaining in the upper 80s to
low 90s at this time.
&&
.AVIATION...(For the 00Z TAFs through 00Z Thursday Evening)
Issued at 558 PM CDT WED AUG 20 2014
Organized convection appears to be a pretty low probability this
evening with models showing the nose of the low level jet mainly
north and east of the terminals. However will keep an eye on the
convection off the higher terrain to the west and see if it is able
to hold together once the boundary layer begins to cool. As for
wind shear, think chances are to small to keep the mention of LLWS
at TOP. RAP and NAM soundings are not as strong with the nocturnal
inversion as the indicated last night and models prog a decent
pressure gradient persisting through the night helping to keep the
boundary layer from completely decoupling.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...Gargan
LONG TERM...Hennecke
AVIATION...Wolters
AREA FORECAST DISCUSSION
NWS JACKSON KY
215 PM EDT WED AUG 20 2014
.UPDATE...
ISSUED AT 1143 AM EDT WED AUG 20 2014
A RATHER CHALLENGING FORECAST THIS MORNING. TAIL END OF FRONTAL
ZONE...BOUNDARY IS EVIDENT ACROSS THE MID WEST THIS MORNING AND WILL
PLAY A MAJOR ROLE IN OUR WEATHER OVER THE NEXT SEVERAL DAYS. BUILDING
RIDGE OF HIGH PRESSURE ALOFT AND TO OUR WEST WILL FORCE THIS BOUNDARY
TO THE EAST OVER THE NEXT 24 HOURS. THIS BOUNDARY WILL BECOME
INCREASINGLY ALIGNED WITH MID AND UPPER LEVEL FLOW PATTERNS AND
BECOME STATIONARY ACROSS THE MID OHIO VALLEY REGION. THEREAFTER IT
SERVES AS A FOCUS FOR CONVECTION AND THE OCCASIONAL CONVECTIVE
COMPLEX OF STORMS. ATTM IT APPEARS AT LEAST PART OF OUR AREA WILL
FEEL THE EFFECTS OF WEAK IMPULSES OF ENERGY RIDING OVER AND DROPPING
DOWN ALONG THE EAST SIDE OF THE RIDGE AXIS.
IMMEDIATE QUESTION IS WILL CURRENT UPSTREAM ACTIVITY OVER IA/IL
MANAGE TO MAKE IT INTO OUR AREA. MOST LIKELY ANSWER LIES WITHIN THE
SYNOPTIC PATTERN THAT IS TAKING SHAPE...BEST DESCRIBED AS AN ALMOST
IDEAL MCS GENERATOR. MODELS SEEM TO HAVE PICKED UP ON THIS AS WELL...
DEPICTING THE SOURCE OF MOISTURE/ENERGY...NAMELY BOUNDARY LAYER H925
TO H850 FLOW INTO THESE STORM COMPLEXES WEAKENING THROUGH THE DAY DUE
TO DIURNAL MIXING...THE INCREASING AGAIN AT NIGHT. THESE COMPLEXES
ONCE GENERATED THEN RIDE SOUTHEAST ALONG THE BOUNDARY. THAT BEING
SAID EXPECT THE CURRENT ACTIVITY ACROSS IA/IL TO WEAKEN A BIT
THROUGH THE DAY. BUT CONFIDENCE IS LOW THAT ACTIVITY WILL COME TO A
COMPLETE END. MOST RECENT RUNS OF THE RAP AND HRRR SUPPORT THIS LINE
OF THOUGHT AND REGIONAL SATELLITE DOES SHOW A DEFINITE WARMING TREND
TO CLOUD TOPS ATTM. DECIDED TO TRIM POPS DOWN JUST A BIT THROUGH THE
AFTERNOON BUT LEAVING ENOUGH TO TO ACCOUNT FOR ISOLD TO SCATTERED
CONVECTION ASSOCIATED WITH DIURNAL HEATING AND ACTIVITY THAT MAY FIRE
ALONG ANY RESIDUAL OUTFLOW BOUNDARIES. PREVIOUS FORECAST HAS POPS
INCREASING AGAIN TONIGHT WHICH IS IN LINE WITH CURRENT THOUGHTS AS
WELL...ESPECIALLY WITH THE SURFACE BOUNDARY SHIFTING TO THE EAST
ACROSS OUR AREA. ALSO TWEAKED HOURLY TEMPS AND WINDS TO BRING THE
GRIDS IN LINE WITH LATEST HOURLY OBS. FINALLY FRESHENED UP ZONES TO
REMOVE MORNING FOG WORDING.
UPDATE ISSUED AT 800 AM EDT WED AUG 20 2014
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL EXIT SOUTHEASTERN
KENTUCKY IN THE NEXT ONE TO TWO HOURS. ONCE THESE STORMS CLEAR THE
AREA...THERE MAY BE SOME ISOLATED TO SCATTERED CONVECTION RE-
DEVELOPING ACROSS EASTERN KENTUCKY THIS AFTERNOON DURING PEAK
HEATING. WILL STAY THE COURSE AND CONTINUE TO MENTION THE
POPS...HOWEVER SOME OF THE GUIDANCE HAS TRENDED DRIER...AND GIVEN THE
SUBSIDENCE FOLLOWING THE DEPARTING WAVE...WOULD NOT BE SURPRISED IF
CONVECTION IS EVEN MORE ISOLATED. UPDATES HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 357 AM EDT WED AUG 20 2014
A COMPLEX OF SHOWERS AND THUNDERSTORMS IS CURRENTLY SLIDING EAST
ACROSS THE OHIO VALLEY ASSOCIATED WITH A PASSING SHORT WAVE TROUGH.
THE MORE ORGANIZED PORTION OF THIS COMPLEX HAS BEEN CONFINED TO ALONG
AND NORTH OF THE MOUNTAIN PARKWAY. THE HRRR MODEL HAS NOT BEEN
HANDLING THIS FEATURE WELL THROUGH THE OVERNIGHT...OVERPLAYING THE
DEVELOPMENT TO THE SOUTH THAT HAS BEEN WEAK IN REALITY...WHILE
UNDERPLAYING WHERE CONVECTION HAS BEEN MORE ORGANIZED AND SUSTAINED.
EXPECT THIS COMPLEX TO KEEP MOVING EAST...AFFECTING LOCATIONS ALONG
AND NORTH OF THE MOUNTAIN PARKWAY FOR THE NEXT FEW HOURS...BEFORE
EXITING THE AREA BY 12Z. THERE WILL BE SOME SUBSIDENCE FOLLOWING THIS
DEPARTING SHORT WAVE FOR TODAY WORKING IN FROM WEST TO EAST...SO HAVE
TRIMMED THE POPS BACK A BIT...PEAKING IN THE 20 TO 30 RANGE FOR MOST
LOCATIONS DURING THE HOTTER PART OF THE DAY. HIGHS TODAY WILL RANGE
FROM 85 TO 90 DEGREES.
AS WE HEAD INTO TONIGHT...CONVECTION WILL BE ON THE DOWNWARD TREND
THROUGH 06Z...BUT THEN LOOKS TO INCREASE BETWEEN 06 AND 12Z...AS
ANOTHER SHORT WAVE TROUGH APPROACHES FROM THE NORTHWEST. POP CHANCES
WILL CONTINUE TO INCREASE THROUGH THE DAY ON THURSDAY WITH HEATING
AIDING THE MODEST FORCING FROM THE PASSING SHORT WAVE. HAVE MAINTAINED
THE BETTER POPS IN THE NORTHEAST...AND LESSER VALUES IN THE
SOUTHWEST...FURTHER REMOVED FROM THE BETTER FORCING. HIGHS WILL
RETURN TO THE 85 TO 90 DEGREE RANGE IN THE SOUTHWEST...WITH MID 80S
IN THE NORTHEAST...WHERE MORE PERSISTENT CLOUD COVER WILL RESIDE.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 335 AM EDT WED AUG 20 2014
THE EXTENDED PORTION OF THE FORECAST BEGINS ON THURSDAY NIGHT WITH A
SLOWLY BUILDING RIDGE OVER THE CENTRAL CONUS AND DIGGING TROUGHS
OVER THE NORTHWEST AND NORTHEAST. THIS GENERAL TREND CONTINUES
THROUGH THE ENTIRE EXTENDED PERIOD. DURING THIS PERIOD...QUITE A FEW
STRONG SHORTWAVES TRAVEL OVER THE BUILDING RIDGE IN THE CENTRAL
PLAINS AND INTO THE OH VALLEY AND GREAT LAKES REGION. THE FIRST WAVE
OF NOTE WILL BE THE SHORTWAVE MOVING THROUGH AT THE BEGINNING OF THE
EXTENDED. AFTER THIS...THE PATTERN TURNS INTO A MORE MCS DRIVEN
PATTERN FRIDAY THROUGH SUNDAY WITH ACTIVITY CENTERED AROUND WHAT THE
DAYS CONVECTION BRINGS AND IS DIURNALLY AFFECTED. THROUGH THE PERIOD
THE UPPER RIDGE SLOWLY WEAKENS AND DRIFTS EAST.
CONCERNING THE MODELS DURING THE EXTENDED...THE GFS AND EURO LOOK TO
BE RIGHT ON TRACK AND IN GOOD AGREEMENT. THOUGH...THE EURO LOOKS TO
CUT OFF ANY CONVECTION BY THE END OF THE EXTENDED AS THE RIDGE AXIS
SETS UP RIGHT OVER EASTERN KENTUCKY LEADING TO AN END TO ALL
DIURNALLY DRIVEN CONVECTION AND DISPLACING THE TRACK OF THE MCS MORE
TO THE NORTHEAST. BASED ON THE GOOD AGREEMENT...IT SEEMS TO BE A
GOOD CONSENSUS TO STAY CLOSE TO THE SOLUTION OF THE ALL BLEND MODEL.
THOUGH DEPENDING ON WHAT THE 00Z EURO DOES ON THE MONDAY AND TUESDAY
TIME FRAME FOR THE RIDGE AXIS RIGHT OVER THE AREA...MAY DROP POPS
BELOW THE ALL MODEL BLEND SOLUTION. WITH THE SOLUTION OF THE ALL
MODEL BLEND...THE BEST CHANCE OF POPS WILL BE DURING THE FRIDAY
THROUGH SUNDAY TIME FRAME AND LESS DURING THE MONDAY AND TUESDAY
TIME FRAME WHERE THE RIDGE WILL BE OVER EASTERN KENTUCKY AND HAVE
LEFT SLIGHT CHANCE MAINLY DURING THE AFTERNOON ON MONDAY AND
TUESDAY.
IN ADDITION TO THIS PATTERN...TEMPERATURES WILL BE ON THE INCREASE
IN EARNEST AS SOME OF THE WARMEST WEATHER OF THE ENTIRE SUMMER WILL
BEGIN TO SET IN FROM FRIDAY THROUGH THE REST OF THE EXTENDED. HIGH
TEMPERATURES WILL SURPASS 90 DEGREES IN SOME AREAS OF EASTERN
KENTUCKY AND HUMIDITY WILL BE ON THE INCREASE AS WELL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 215 PM EDT WED AUG 20 2014
VERY JUICY AIR IN THE BOUNDARY LAYER IS RESPONSIBLE FOR LOW SC FIELD
IN PLACE ACROSS THE AREA. CIGS HAVE GENERALLY BEEN WITHIN THE MVFR
THRESHOLDS. WITH MIXING AND INCREASED HEATING...CLOUD BASE OF CU/SC
FIELD SHOULD RISE JUST A BIT THROUGH THE AFTERNOON. OTHERWISE
CONFIDENCE IS LOW ON EXACTLY HOW UPSTREAM STORM COMPLEX OVER IL/IN
WILL AFFECT OUR AREA. MODEL GUIDANCE SUGGEST THE SYSTEM WILL FALL
APART BEFORE ACTIVITY REDEVELOPS LATER TONIGHT ALONG A SURFACE
FRONTAL BOUNDARY THAT WILL TRANSIT OUR AREA. FOLLOWED THIS TRAIN OF
THOUGHT PRETTY CLOSELY FOR THE FORECAST. IN ADDITION...GUIDANCE IS
HITTING FOG ACROSS THE AREA PRETTY HARD TONIGHT. BUT WITH EXTENSIVE
CLOUD COVER MOVING BACK INTO THE AREA TENDENCY WAS TO GO MORE
OPTIMISTIC. VERY WEAK UPPER LEVEL DISTURBANCE WILL APPROACH BETWEEN
06 AND 12Z...AND BE THE CATALYST FOR THE AFOREMENTIONED RENEWED
CONVECTIVE THREAT. THEREAFTER...THE SURFACE FRONTAL BOUNDARY WILL
BECOME STATIONARY TO OUR EAST AND BECOME THE FOCUS OF ADDITIONAL
SHOWERS AND THUNDERSTORMS OVER THE NEXT SEVERAL DAYS. WINDS WILL BE
LIGHT AND GENERALLY FROM THE WEST SOUTHWEST THROUGH THE FORECAST
PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
UPDATE...RAY
SHORT TERM...GEOGERIAN
LONG TERM...SHALLENBERGER
AVIATION...GEOGERIAN/RAY
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
137 PM EDT Wed Aug 20 2014
...Updated Forecast and Aviation Discussions...
...Forecast Update...
Issued at 135 PM EDT Wed Aug 20 2014
Complex across central Illinois is holding together fairly well
early this afternoon. Have a pretty thick canopy of cirrus out ahead
of the storms, but it may hold together enough as it moves into our
forecast area. High-res models are not too gung ho about rain
chances in this area this afternoon, but with a very unstable
surface-based atmosphere in our region, SPC mesoanalysis has 4-6 k
CAPEs, just cannot rule out storms developing/maintaining. Have
shifted the highest pop axis a little south, to a Huntingburg, IN to
Danville, KY line. Will continue to watch incoming pattern for
updates through the afternoon.
Issued at 1135 AM EDT Wed Aug 20 2014
Partly cloudy skies were noted across southern Indiana and central
Kentucky this morning. Temperatures ranged from the upper 70s to
near 80- in the east/northeast with lower 80s generally in the I-65
corridor and points west. From the KY Mesonet data and visible
satellite imagery, there appears to be boundary draped across the
southern part of the forecast area. This evident in the dewpoint
readings across southern KY which are in the middle 70s with only
upper 60s to lower 70s across our NE sections.
A decaying MCS over central IL will continue to spread mid-high
level cloudiness down into mainly western KY this afternoon. These
clouds along with the boundary in the region may serve as a focus
for convective development later this afternoon. The high
resolution convection allowing models have vastly different
solutions. The latest runs of the HRRR keep much of our region dry
thought the day with convection mainly developing out to our west.
While the NSSL WRF ARW runs develop convection up near CVG and drop
it SE into WFO JKL`s region. The mixed signals in the guidance make
this forecast particularly challenging this afternoon.
For now, have kept the current forecast on track. Current thinking
is that convection will probably start to develop over the next few
hours along the left over boundary...given multiple convectively
induced lifting mechanisms cross the region. Damaging winds and
perhaps some large hail will be possible with the storms this
afternoon as moderate instability combined with around 30 kts of
WNW flow aloft will be in place across the region.
.SHORT TERM (Now through Thursday)...
Issued at 340 AM EDT Wed Aug 20 2014
A complex short term forecast is in store with multiple rounds of
strong to potentially severe convection possible as potent
shortwaves topple a central CONUS ridge and dive southeast into the
Ohio Valley. In addition, the eastern edge of a warm front will
slowly lift north over the region over the next few days providing
focus for convection. Also left over boundaries from storms
will provide focus for renewed convection over the next few days
with convective activity peaking during the afternoon and evening
hours during best instability.
As of 315am this morning, convection over the Bluegrass region was
causing mainly very heavy rainfall and lots of lightning. A flood
advisory is effect for northern Harrison County KY through 6am this
morning due to training storms over that area. The Harrison County
mesonet has received 1.34 inches of rain so far with impressive
rainfall rates which may cause minor flooding issues.
Think that this complex of storms will move east of the area within
the next 1-2 hrs and we may see a dry period through the morning
hours. Expect a left over boundary from convection over central
Indiana yesterday evening to settle somewhere near the Ohio River
over portions of southern Indiana and north central Kentucky.
Believe this boundary will be key for redevelopment of convection
this afternoon.
Most short range models indicate a shortwave will dive south into
the area this evening. Ahead of this wave, expect the atmosphere to
become very unstable with only partly cloudy skies in the wake of
morning convection. Bulk shear will increase ahead of the wave as
early as 1-3pm this afternoon. This is when we may see convection
begin to fire in the region of the left over sfc boundary.
Convection should be enhanced in strength and coverage during the
evening hours as the shortwave passes through. It is a bit unclear
how long into the evening and overnight hours convection will
continue. It may survive for a prolonged period of time if a good
cold pool and outflow boundaries get going. At some point late
tonight into tomorrow morning expect a break in showers/storms.
Another notable shortwave looks to impact mainly northern KY and
southern Indiana with storms for Thurs afternoon/evening as well.
Models generally do not have a good handle on ongoing convection and
evolution so confidence is rather low on exact timing. However,
model soundings indicate increased bulk shear values with each wave
and excellent instability so storms will likely be strong to severe
in nature today through Thurs with damaging winds, large hail, and
torrential rainfall all possible. PWATs will hover in the 1.6-2
inch range resulting in some heavy rainers and potential flood
problems.
As for temperatures, think that highs will range from the upper 80s
to lower 90s today and tomorrow with locations west of I-65 likely
seeing max heat indices near 100 each afternoon. Low temperatures
tonight will be mild in the lower 70s.
.LONG TERM (Thursday night through Tuesday)...
Issued at 311 AM EDT Wed Aug 20 2014
Thursday night through Tuesday...
Expect a hot spell throughout the entire extended period, at least
through the middle portion of next week.
In an upper air pattern that we`ve not seen much of this summer,
strong 500mb ridging will develop initially across the lower
Mississippi Valley by Thursday evening, with longwave troughs
located over the Pacific Northwest and New England. The wavelength
of this trough-ridge-trough pattern will lead to a stagnant pattern.
The GFS for example holds this ridge in place through at least late
Monday, building it northwards towards the Commonwealth. We should
expect probably a week`s worth of hot sticky humid weather with
highs well into the 90s and warm overnight lows in the lower to mid
70s over the weekend and into the middle of next week. Rising Heat
Indices may be a concern for early next week.
In this type of pattern, shortwaves moving along the periphery of
500mb ridging can bring episodic convection. Initially, Thursday
night through Sunday, scattered thunderstorms may develop within a
northwest flow pattern along the northeastern edge of this building
ridge. This would favor southeastern Indiana, southern Ohio and the
northern Bluegrass for possible scattered thunderstorms,
concentrated during the afternoon and evening hours. Southwestern
Kentucky, closer to the warm temperatures aloft associated with this
ridge, will likely stay dry.
By Monday and Tuesday, think the entire region will be dry, as
ridging builds northwards into the Commonwealth.
&&
.AVIATION (18Z TAF Update)...
Issued at 125 PM EDT Wed Aug 20 2014
Confidence in convective forecast this period is low, as cirrus
shield from storms to our northwest quickly moves into the region.
Have some cumulus developing over the central forecast area this
hour, and SPC mesoanalysis indicates plenty of instability across
the region. However, the cirrus canopy should provide some
subsidence to inhibit convection. There is still a possibility that
the storms to our northwest can remain organized enough to bring
those storms to the terminals later this afternoon. Thus have gone
with vicinity storms over a larger period of time and will update as
the afternoon progresses. May even get into another round of precip
later tonight, as additional disturbances move in from the
northwest, but a lot will depend on what happens this afternoon. Fog
forecast for Thursday morning will depend on that as well. Given
very high dewpoints across BWG this hour, have enough confidence to
go with a period of MVFR conditions, as in current guidance.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Updates........MJ/RJS
Short Term.....AMS
Long Term......JSD
Aviation.......RJS
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
256 PM EDT WED AUG 20 2014
.SYNOPSIS...
A STATIONARY BOUNDARY WILL REMAIN OVER THE REGION THROUGH THURSDAY.
THE BOUNDARY WILL SLOWLY DROP SOUTH AND WEST AS A COLD FRONT FRIDAY
AND HIGH PRESSURE OVER NEW ENGLAND WILL EXTEND INTO OUR AREA FOR THE
WEEKEND. HOWEVER...UNSETTLED CONDITIONS MAY PERSIST DURING THIS TIME
DUE TO PLENTY OF MOISTURE FROM THE ATLANTIC.
&&
.NEAR TERM /THROUGH THURSDAY/...
AN UPPER LEVEL TROUGH IS LOCATED ACROSS THE GREAT LAKES WHILE
MULTIPLE DISTURBANCES MOVE ACROSS THE MID WEST IN NORTHWEST FLOW
ALOFT. A JET STREAK IS ROUNDING THE BASE OF THE TROUGH ACROSS THE
GREAT LAKES AND OHIO VALLEY.
A WEAKENING SHORTWAVE TROUGH WILL CONTINUE TO MOVE ACROSS THE
ALLEGHENY FRONT THIS AFTERNOON WHILE SHOWERS AND THUNDERSTORMS MOVE
EASTWARD ACROSS THE POTOMAC HIGHLANDS...SHENANDOAH VALLEY AND
NORTHERN VA. MESOSCALE ANALYSIS SHOWS 500-1000 J/KG WEST OF I-95 AND
25-30KTS OF SHEAR. PWATS HAVE RISEN TO 1.6-1.8 INCHES ACROSS THIS
REGION. AN ISOLATED SEVERE THREAT WILL CONTINUE THIS AFTERNOON
WITH DMG WINDS AS THE MAIN THREAT. BOWING SEGMENTS AND RIJ
SIGNITURES HAVE BEEN OBSERVED ON RADAR. AT THIS TIME...HAVE NOT
CONFIRMED GROUND TRUTH REPORTS FOR DMG WINDS. HEAVY RAINFALL HAS
ALSO BEEN OBSERVED. HRRR INCREASES COVERAGE OF SHOWERS AND
THUNDERSTORMS AND ACTIVITY SHOULD REACH THE I-95 LATE THIS
AFTERNOON AND EARLY EVENING.
SHOWERS AND THUNDERSTORMS WILL DECREASE IN COVERAGE THIS EVENING.
SOUTHERLY FLOW AT THE SFC WILL KEEP MOIST CONDITIONS ACROSS THE MID
ATLANTIC. PATCHY FOG IS POSSIBLE ACROSS THE REGION MAINLY IN VALLEY
LOCATIONS AND LOCATIONS THAT RECEIVED RAIN TODAY.
THE UPPER LEVEL TROUGH WILL MOVE ACROSS ONTARIO BY THURSDAY MORNING
AS A RIDGE BUILDS INTO THE CENTRAL PLAINS. MULTIPLE DISTURBANCES
ARE EXPECTED TO MOVE ACROSS THE MID WEST BUT TIMING IS DIFFICULT.
A SFC TROUGH IS EXPECTED ACROSS THE REGION THURSDAY. THIS WILL
PRODUCE WESTERLY WINDS BEHIND THE TROUGH AND SOUTHERLY FLOW AHEAD
OF THE TROUGH. AT THIS TIME...A DISTURBANCE IS EXPECTED TO APPROACH THE
REGION THURS AFTERNOON FROM THE NORTHWEST. SHOWERS AND
THUNDERSTORMS WILL MOVE INTO THE REGION AT THIS TIME AND MOVE
EAST-SOUTHEAST. THE SFC TROUGH WILL ALSO LEAD TO ISOLATED
DEVELOPMENT IN THE AFTERNOON. AT THIS TIME...INSTABILITY WILL BE
MARGINAL AND SHEAR SEEMS WEAK. ACTIVITY SHOULD BE SUB-SEVERE. PWATS
ARE EXPECTED TO RISE NEAR 1.9 INCHES THURSDAY PRODUCING HUMID
CONDITIONS. SHOWERS AND THUNDERSTORMS WILL BE CAPABLE OF PRODUCING
HEAVY RAIN.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE THURSDAY NIGHT
AND INTO FRIDAY AS A 250MB JET SITS NEAR THE REGION AND
DISTURBANCES APPROACH FROM THE GREAT LAKES. SUBSIDENCE BEHIND THE
DEPARTING DISTURBANCES MAY LEAD TO CLEARING FRIDAY AND THEREFORE
INSTABILITY WILL LIKELY INCREASE. AT THIS TIME...CONFIDENCE IS LOW
ON THE TIMING OF SHOWERS AND THUNDERSTORMS. FCST MAX TEMPS WILL
REACH THE LOW 80S ON FRIDAY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
A WEAK WAVE OF LOW PRESSURE FOCUSED IN THE MID AND UPPER LEVELS
WILL CROSS THE AREA OVERNIGHT FRIDAY...PROVIDING ONE FINAL PERIOD OF
ENHANCED RAINFALL AS A BACKDOOR COLD FRONT MOVES THROUGH AT THE
SURFACE. A SUBTROPICAL RIDGE WILL BUILD OVER THE EASTERN US FOR
WEEKEND AS SURFACE HIGH PRESSURE CENTERED OVER THE NORTHEASTERN US
RIDGES DOWN THE EASTERN SEABOARD. THIS RIDGING COMBINED WITH
EASTERLY FLOW AROUND THE NORTH SIDE OF A COASTAL LOW OFF OF CAPE
HATTERAS WILL BRING ONSHORE FLOW FOR THE MID-ATLANTIC MIDDAY
SATURDAY THROUGH THE BEGINNING OF NEXT WORKWEEK. THE MARINE LAYER
THAT WILL FILL IN WILL BRING SEASONABLY COOL AND MOIST AIR...LEADING
TO A LOW CLOUD DECK THAT WILL HANG AROUND THROUGH THE WEEKEND AND
LIKELY INTO MONDAY EVENING...PARTICULARLY EAST OF THE BLUE RIDGE.
CHANCE POPS WILL REMAIN IN THE FORECAST ALONG AND WEST OF THE BLUE
RIDGE WHERE THERE WILL BE AN UPSLOPE COMPONENT TO THE MOIST EASTERLY
FLOW.
THE SURFACE HIGH WILL MIGRATE OFF OF THE MID-ATLANTIC COAST MONDAY
NIGHT AND SOUTHERLY FLOW WILL BEGIN TO FILL IN LOCALLY. THIS WILL
SIGNAL AN INCREASE IN TEMPERATURES AS HIGHS WILL GO FROM THE MID TO
UPPER 70S SATURDAY THROUGH MONDAY TO NEAR 80 TUESDAY AND MID 80S
WEDNESDAY. NO SIGNIFICANT PRECIPITATION FEATURES ARE EXPECTED
THROUGH THE FIRST HALF OF NEXT WEEK.
&&
.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
SHRA AND TSRA IS EXPECTED THIS AFTERNOON AS A LINE OF TSRA MOVES
EASTWARD. GUSTY WINDS AND IFR VSBYS POSSIBLE IN TSRA. THIS WILL
CONTINUE THIS AFTERNOON. SOUTHERLY FLOW WILL KEEP MOISTURE IN THE
REGION OVERNIGHT AND PATCHY IFR VSBYS ARE POSSIBLE AT MRB AND CHO.
MVFR VSBYS ARE POSSIBLE AT IAD. MVFR/IFR CIGS ARE POSSIBLE NEAR
BWI-MTN BUT CONFIDENCE IS LOW AT THIS TIME.
SHRA AND TSRA POSSIBLE THURSDAY AFTERNOON AND INTO FRIDAY AND MAY
CAUSE MVFR/IFR RESTRICTIONS.
PERIODS OF LOW CEILINGS ARE POSSIBLE AS A MID AND UPPER LEVEL
DISTURBANCE CROSSES THE AREA FRIDAY NIGHT AND THEN AGAIN OVER THE
WEEKEND AND INTO EARLY NEXT WEEK AS A MARINE AIRMASS SETTLES INTO
THE AREA.
&&
.MARINE...
SOUTHERLY FLOW WILL CONTINUE ON THE WATERS THROUGH FRIDAY. WINDS
SHOULD STAY BELOW SCA CRITERIA. SHOWERS AND THUNDERSTORMS ARE
EXPECTED THIS EVENING AND AGAIN THURSDAY AFTERNOON AND NIGHT. SOME
THUNDERSTORMS MAY PRODUCE GUSTY WINDS.
A SMALL CRAFT ADVISORY MAY BE NECESSARY SATURDAY NIGHT THROUGH
SUNDAY NIGHT IN BREEZY EASTERLY FLOW AROUND THE NORTH SIDE OF A
COASTAL LOW OFF OF THE NORTH CAROLINA FLOW.
&&
.TIDES/COASTAL FLOODING...
AN ONSHORE FLOW WILL CONTINUE THROUGH TONIGHT...BUT IT WILL REMAIN
WEAK. THE FLOW MAY TURN MORE TOWARD THE SOUTHEAST WHICH WOULD CAUSE
WATER LEVELS TO BE SLIGHTLY HIGHER THAN THEY HAVE BEEN RECENTLY.
THIS WILL CAUSE WATER LEVELS TO BE CLOSE TO MINOR FLOODING
THRESHOLDS DURING THE HIGH TIDE CYCLE LATE TONIGHT INTO EARLY
THURSDAY MORNING.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...HAS
NEAR TERM...HAS
SHORT TERM...HAS
LONG TERM...CEB
AVIATION...HAS/CEB
MARINE...HAS/CEB
TIDES/COASTAL FLOODING...LWX
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
357 PM CDT WED AUG 20 2014
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 354 PM CDT WED AUG 20 2014
RATHER DIFFICULT FORECAST TONIGHT. THERE HAVE BEEN LOTS OF MID LEVEL
CLOUDS HANGING ACROSS THE AREA THIS AFTERNOON...AND HAVE KEPT
TEMPERATURES DOWN A BIT. CLOUDS HAVE BEGUN TO CLEAR SLOWLY...AND ARE
NOW ALLOWING FOR SOME HEATING AND INCREASING INSTABILITY. DO NOT
HAVE A GOOD FEEL IN TERMS OF CONVECTION TONIGHT...AS MODELS HAVE
BEEN INCONSISTENT AND PRIMARY FORCING REMAINS MOSTLY NORTH OF THE
AREA. FOR THESE REASONS...WILL LOWER POPS A BIT. AS
MENTIONED...INSTABILITY IS INCREASING WITH LITTLE SURFACE BASED CIN
REMAINING ACROSS THE AREA. AN ELONGATED AREA OF LOW PRESSURE EXTENDS
FROM WESTERN SD TO WESTERN KS...AND COULD BE THE FOCUS FOR ISOLATED
STORM DEVELOPMENT THOUGH THE EVENING. A WARM FRONT ALSO EXTENDS FROM
WEST TO EAST ACROSS NORTHERN NEBRASKA...AND COULD ALSO SERVE AS A
FOCUS FOR STORM DEVELOPMENT. YET ANOTHER AREA TO WATCH WILL BE
ACROSS NORTHEAST COLORADO THIS EVENING...AS HRRR MODEL CONTINUES TO
INDICATE STORMS MOVING NORTHEAST INTO SOUTHWEST NEBRASKA THIS
EVENING. SO LOTS OF AREAS TO WATCH...BUT LOW CONFIDENCE ON ANY ONE
SCENARIO MATERIALIZING. WILL CONTINUE TO MONITOR.
WEAK COOL FRONT WILL SETTLE JUST SOUTHEAST OF THE AREA THURSDAY.
OVERALL SHOULD BE A FAIRLY QUITE WEATHER DAY...WITH LIGHT NORTH
WINDS AND TEMPERATURES IN THE UPPER 80S AND LOWER 90S.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 354 PM CDT WED AUG 20 2014
MAIN FOCUS WILL BE THE STORM SYSTEM MOVING IN THIS WEEKEND WITH
THUNDERSTORM CHANCES THURSDAY THROUGH SUNDAY.
LOWERED PRECIPITATION CHANCES ACROSS THE SOUTHERN PART OF THE
FORECAST AREA AS THE LATEST MODELS ARE TRENDING DRIER DUE TO LACK
OF MOISTURE. KEPT THE POPS ACROSS THE NORTHWEST AS MODELS SEEM TO
FAVOR STRONGER FORCING AND BETTER MOISTURE AS AN UPPER LEVEL SHORT
WAVE TROF PUSHES ACROSS THE AREA. HELD OFF HIGHER PRECIPITATION
CHANCES ACROSS THE SOUTHWEST UNTIL FRIDAY AFTERNOON AND EVENING AS
CONFIDENCE IS GREATER IN THUNDERSTORM DEVELOPMENT AFTER 18Z. SYSTEM
CURRENTLY ACROSS THE SOUTHWESTERN U.S. WILL CONTINUE TO ADVECT
NORTHEASTWARD AND WILL COMBINE WITH THE NORTHERN SYSTEM CURRENTLY
ACROSS THE GULF OF ALASKA. THE SOUTHWEST SYSTEM WILL TRANSPORT
MOISTURE AND VORTICITY ACROSS THE FORECAST AREA FRIDAY AFTERNOON.
BY 00Z SATURDAY PRECIPITABLE WATER INCREASES TO 150 PERCENT.
SATURDAY NIGHT INTO SUNDAY...AN UPPER LEVEL SHORT WAVE TROF WILL
PUSH ACROSS THE FORECAST AREA PUSHING THE RIDGE EASTWARD BRINGING
COLDER TEMPERATURES WITH IT. HIGHS ON SUNDAY WILL BE AROUND 10
DEGREES COOLER THAN SATURDAY. COOLER TEMPERATURES WILL CONTINUE
THROUGH WED WHEN NEXT TROF IS SET TO PUSH THROUGH THE AREA. THIS
SYSTEM WILL BRING STRONG LIFT AS MODELS SUGGEST AN INCREASE IN OMEGA
VALUES AND AN ABUNDANT AMOUNT OF MOISTURE WITH DEWPOINTS IN THE 60S
CREATING A FAVORABLE THUNDERSTORM DEVELOPMENT TO BE IN PLACE THE
NEXT SEVERAL DAYS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 108 PM CDT WED AUG 20 2014
A WARM FRONT WILL BE LOCATED FROM EAST TO WEST ACROSS NORTH
CENTRAL AND NORTHEAST NEBRASKA THIS AFTERNOON. SCATTERED
THUNDERSTORMS ARE POSSIBLE ALONG AND NORTH OF THE FRONT LATE THIS
AFTERNOON AND EVENING. OTHER ISOLATED TO SCATTERED THUNDERSTORMS
ARE EXPECTED TO DEVELOP ACROSS NORTHEAST COLORADO AND COULD MOVE
NORTHEAST INTO SOUTHWEST NEBRASKA THIS EVENING. WILL NOT INCLUDE
MENTION IN THE OFFICIAL TAF FORECASTS...AS COVERAGE IS NOT
EXPECTED TO BE WIDESPREAD. WINDS WILL GENERALLY BE LIGHT THROUGH
TONIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...TAYLOR
LONG TERM...GOMEZ
AVIATION...TAYLOR
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
334 PM CDT WED AUG 20 2014
.SHORT TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 334 PM CDT WED AUG 20 2014
UNSETTLED WEATHER PATTERN WILL REMAIN IN PLACE OVER THE NEXT WEEK
WITH SEVERAL OPPORTUNITIES FOR THUNDERSTORMS. TIMING THESE CHANCES
ALONG WITH INCREASE IN HEAT AND HUMIDITY ARE THE PRIMARY FORECAST
CONCERNS.
MORNING UPPER AIR CHARTS SHOWED MID LEVEL TROUGH EXTENDING FROM THE
CANADIAN ROCKIES INTO SOUTHERN CALIFORNIA...WITH SOUTHWEST FLOW
AHEAD OF THE TROUGH RIDING INTO THE NORTHERN PLAINS. UPPER RIDGE
AXIS WAS CURRENTLY OVER THE MISSOURI RIVER VALLEY...BUT IS FORECAST
TO SHIFT EAST AND FLATTEN A BIT ON THURSDAY. THIS WILL LEAVE OUR
AREA UNDER SOUTHWEST FLOW ALOFT...WITH PATH FOR EJECTING SHORTWAVES
OVER NEBRASKA AND THE DAKOTAS. ALSO OF NOTE WAS PLUME OF MID LEVEL
MOISTURE EXTENDING FROM THE SOUTHERN BAJA INTO WESTERN KANSAS AND
SOUTHWEST NEBRASKA. WITH ONLY A SLOW DRIFT TO WESTERN
TROUGH...EXPECT THIS MOISTURE PLUME TO EXPAND OVER EASTERN NEBRASKA
AND WESTERN IOWA AND REMAIN IN PLACE AT LEAST INTO THE WEEKEND.
USING 700MB DEW POINT TEMPERATURES AS A PROXY...MODELS CONCUR WITH
THIS EXPECTATION. THE RESULT OF THESE PARAMETERS WILL BE AN
ATMOSPHERE PRIMED FOR SCATTERED CONVECTION AS SHORTWAVES ROLL INTO
THE PLAINS.
TIMING OF THOSE SHORTWAVES WILL PROVE DIFFICULT MORE THAN A DAY TO
TWO OUT. HOWEVER MODELS AGREE ON A SIGNIFICANT SHORTWAVE MOVING INTO
THE PLAINS FRIDAY NIGHT...OUR MOST LIKELY TIME FOR WIDESPREAD HEAVY
RAINS.
FOR TONIGHT...WATER VAPOR LOOPS IMPLY A SHORTWAVE IN WESTERN KANSAS
THIS AFTERNOON...EXPECTED TO LIFT NORTHEAST ACROSS OUR CWA LATER
THIS EVENING AND OVERNIGHT. GREATER THAN 7 C/KM MID LEVEL LAPSE
RATES WILL BE IN PLACE ALONG WITH ABUNDANT MID LEVEL MOISTURE.
EXPECT SCATTERED THUNDERSTORMS TO FIRE AFTER MIDNIGHT WHEN LOW LEVEL
JET KICKS UP TO 35KT WITH APPROACH OF SHORTWAVE. MAIN AREA OF
CONCERN WILL BE OVER OUR NORTHERN CWA THEN. HOWEVER THIS
EVENING...CONVECTION FROM EARLIER THIS MORNING MOVING ACROSS IOWA
LAID DOWN AN OUTFLOW BOUNDARY WHICH MOVED INTO SOUTHWEST IOWA AND
NORTHERN MISSOURI. VISIBLE SATELLITE PICS SHOW A LINE OF CUMULUS
ALONG THIS BOUNDARY...AND RAP MODEL SUGGESTS MLCAPE IS APPROACHING
3500 J/KG IN NORTHWEST MISSOURI ALONG WITH DIMINISHING CAP. LATEST
RAP AND HRRR FORECASTS KEEP CONVECTION IN CHECK THERE...BUT HAVE
ADDED SMALL POPS FOR SEVERAL HOURS THIS EVENING.
OVERNIGHT CONVECTION SHOULD BE EXITING THE CWA OR DIMINISHING BY MID
MORNING. EXPECT CLOUDS TO CLEAR ALLOWING FOR PLENTY OF INSOLATION IN
THE AFTERNOON WITH TEMPERATURES WELL INTO THE 90S AND DEW POINTS
CLOSE TO 70. A WEAK FRONTAL BOUNDARY IS FORECAST TO SETTLE INTO
NORTHEAST NEBRASKA THURSDAY AFTERNOON BEHIND WEDNESDAY NIGHT
SHORTWAVE...AND COULD FOCUS THUNDERSTORM CHANCES THERE. RELATIVELY
WARM TEMPERATURES ALOFT WILL LIKELY SUPPRESS CONVECTION IN THE
AFTERNOON...WITH BETTER CHANCES COMING LATER IN THE EVENING AS THE
FRONT SETTLES SOUTH INTO SOUTHEAST NEBRASKA AND SOUTHWEST IOWA AND
MID LEVEL TEMPERATURES COOL A BIT. CONTINUED ISENTROPIC UPGLIDE OVER
FRONTAL BOUNDARY IN MOIST ATMOSPHERE SUGGESTS AT LEAST SCATTERED
CONVECTION IS POSSIBLE THROUGH THE NIGHT.
MOST OF DAY FRIDAY SHOULD BE DRY AFTER MORNING STORMS IN THE SOUTH
MOVE OFF TO THE EAST. FRONTAL BOUNDARY WILL BEGIN LIFTING TO THE
NORTH DURING THE DAY WITH APPROACH OF STRONG SHORTWAVE FRIDAY NIGHT.
INSTABILITY FORECASTS SHOW 2000-3000 J/KG OF SURFACE-BASED CAPE
FRIDAY AFTERNOON...BUT SOUNDINGS SUGGEST A MODEST CAP WILL HOLD OFF
STORMS UNTIL NEAR 00Z OR PROBABLY AFTER. CHANCES INCREASE MARKEDLY
FRIDAY NIGHT AS SHORTWAVE AND SURFACE LOW MOVE NORTHEAST THROUGH THE
CWA. CURRENT TRACK PLACES NORTHEAST NEBRASKA IN THE CORRIDOR OF
HEAVIEST POTENTIAL RAINFALL WHERE PRECIPITABLE WATER WILL LIKELY
EXCEED 2 INCHES. CURRENT HPC QPF PROGS PAINT ABOUT THREE-QUARTERS OF
AN INCH OF RAIN IN NORTHEAST NEBRASKA...BUT WILL LIKELY SEE MUCH
MORE THAN THAT IN LOCAL AREAS GIVEN MOISTURE AVAILABLE AND POTENTIAL
FOR TRAINING OF STORMS. EXPECT ACTIVITY TO BE EXITING TO OUR
NORTHEAST SATURDAY MORNING...BUT LEFTOVER BAROCLINIC ZONE AND WIND
SHIFT WILL REMAIN IN PLACE FOR THE POTENTIAL FOR MORE STORMS LATER
IN THE DAY SATURDAY. WILL MAINTAIN A SMALL CHANCE FOR ADDITIONAL
AFTERNOON STORMS...EXPECTING SUBSIDENCE BEHIND EXITING SHORTWAVE TO
SUPPRESS CONVECTION MOST OF THE AFTERNOON.
.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 334 PM CDT WED AUG 20 2014
CONTINUED CHANCES OF THUNDERSTORMS WILL REMAIN JUST ABOUT EACH
PERIOD IN THE LONGER TERM FORECAST THROUGH WEDNESDAY. WESTERN UPPER
TROUGH WILL SLOWLY DRIFT FROM THE ROCKIES SATURDAY NIGHT INTO THE
PLAINS BY WEDNESDAY. ECMWF IS A LITTLE MORE PROGRESSIVE THAN THE GFS
WITH THIS MOVEMENT...BUT EVEN THE ECMWF LEAVES SOME SEMBLANCE OF A
TROUGH/LOW IN THE PLAINS THEN.
USING A BLEND OF ECMWF AND GFS...AND WHERE SOME CONSISTENCY IS
SHOWN...BEST CHANCES FOR MORE WIDESPREAD CONVECTION IS EXPECTED
MONDAY NIGHT INTO TUESDAY...THEN AGAIN TUESDAY NIGHT INTO WEDNESDAY.
BEFORE THEN...IMPULSES RIDING THROUGH MID LEVEL FLOW COULD SPARK
AREAS OF STORMS AT JUST ABOUT ANY TIME AS FRONTAL BOUNDARY MEANDERS
NORTH AND SOUTH THROUGH THE CWA AHEAD OF AND BEHIND EACH WAVE.
TEMPERATURES SHOULD MODERATE SOME THROUGH THE PERIOD...BEGINNING
WITH SUNDAY IN THE 80S TO NEAR 90...THEN RANGING FROM THE UPPER 70S
TO MIDDLE 80S MONDAY THROUGH WEDNESDAY.
&&
.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1242 PM CDT WED AUG 20 2014
ONGOING CONVECTION OVER NORTHEAST NEBRASKA HAS BEEN LIFTING NORTH
DURING THE MORNING AND THIS TREND IS EXPECTED TO CONTINUE INTO THE
AFTERNOON AS WARM FRONT MOVES NORTH TO ALONG THE NEBRASKA SOUTH
DAKOTA BORDER BY 00Z. SOME CHANCE OF THUNDERSTORMS AFTER 06Z AT
KOFK AS WEAK TROUGH MOVES INTO NORTH CENTRAL NEBRASKA BUT LESS
LIKELY AT KOMA AND KLNK WHERE SOME CAPPING EXPECTED. VFR
CONDITIONS WILL PREVAIL OUTSIDE OF THUNDERSTORM ACTIVITY.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...DERGAN
LONG TERM...DERGAN
AVIATION...FOBERT
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1252 PM CDT WED AUG 20 2014
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 323 AM CDT WED AUG 20 2014
MESO ANALYSIS THIS MORNING INDICATING HIGH DEGREE OF
MOISTURE/INSTABILITY IN PLACE OVER THE REGION WITH PWS OVER 1.5"
AND MUCAPES AROUND 2000 J/KG. MEANWHILE INTENSE LLVL MOISTURE ADV
WAS FEEDING CONVECTIVE ACTIVITY WHICH HAS BLOSSOMED OVER CNTRL NEB
AND CNTRL SD ALONG AXIS OF DEEP LYR MOIST CONVERGENCE/BNDRY LYR
THETA-E ADV/315K ISENTROPIC UPGLIDE.
LAST SEVERAL RUNS OF HIRES HRRR SUGGESTING LINE OF CONVECTION
ORIENTED NW-SE WILL FIRE OVER THE CWA SOMETIME TWD SUNRISE THIS
MORNING. HRRR THEN LIFTS ACTIVITY NEWD TWD THE UPPER MIDWEST AND OUT
OF THE CWA BY 18Z THIS AFTN.
HEADING INTO THIS WEEKEND...GOOD MODEL AGREEMENT HIGH PRESSURE DOME
WILL BUILD OVER THE SERN STATES WILL ACT AS A BLOCK RESULTING IN
UPSTREAM AMPLIFICATION OF UPPER TROF OVER THE WRN CONUS. IN
ADDITION...BULK OF PCPN ACTIVITY IS PROGGED TO BE NOCTURNAL IN
NATURE THE REST OF THIS WEEK WITH BULK OF RAINFALL FOUND MAINLY
NORTH OF THE CWA. HOWEVER...QUITE PROBABLE THE CWA WILL SEE ITS
FAIR SHARE OF MUCH NEEDED PCPN THE NEXT SEVERAL DAYS.
TONIGHT...EXPECT CONVECTION TO FIRE FROM ERN SD TO SW NEB ALONG
INSTABILITY AXIS WHERE BNDRY LYR THETA-E CONVG WILL BE MOST
PREVALENT. ACTIVITY PROGGED TO EVENTUALLY ORGANIZE INTO A COMPLEX
AND SLOWLY MIGRATE EWD OVER ERN SD OVERNIGHT. IS LIKELY THAT SRN
PORTION OF MCS WILL PUSH DEEP INTO THE CWA...THUS FEEL COMPELLED
PUSH POPS INTO THE LIKELY CAT DURING THE OVERNIGHT TONIGHT.
THURSDAY NIGHT CONVECTION NOT LOOKING ALL THAT IMPRESSIVE AT THIS
POINT AND ANY ACTIVITY THAT DOES DEVELOP WILL BE LIGHTLY SCATTERED
IN NATURE AT BEST. THEREFORE TOKEN LOW POPS SEEM TO BE THE BEST FIT
FOR NOW. FRIDAY NIGHT THOUGH LOOKING RATHER PROMISING FOR GENEROUS
RAINFALL ASSOCIATED WITH ANTICIPATED NIGHTTIME COMPLEX. ENVIRONMENT
AT THAT TIME WILL BE PRIME WITH WARM CLOUD DEPTH OF 4K METERS...PWS
MORE THAN 2"...KI AOA 40...LLVL JET MOISTURE TRANSPORT FEED. MOST
LIKELY THAT HEAVIER RAINFALL AMOUNTS WILL BE FOUND OVER THE NRN
CWA...THUS WILL MENTION IN ZFP.
.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 323 AM CDT WED AUG 20 2014
FEATURE OF INTEREST STILL IS UPPER TROF OVER WRN CONUS RESPONSE TO
BLOCKING HIGH PRESSURE DOME OVER THE SERN CONUS WITH RATHER COOL
CANADIAN AIRMASS SWEEPING INTO THE NRN/CNTRL PLAINS EARLY NEXT WEEK.
GOING FCST WITH MAX TEMPS GENERALLY IN THE MID/UPPER 70S
MON/TUES/WED STILL LOOK REASONABLE FOR NOW. PCPN CHANCES IN THE EXT
PDS REMAINS CENTERED AROUND VERY SLOW MOVING COLD FRONTAL LEADING
THE CANADIAN AIR MASS INTO THE REGION FOLLOWED BY POST FRONTAL PCPN
ASSOCIATED WITH APPROACHING UPPER TROF. WITH ECM/GFS QPF IN RATHER
GOOD AGREEMENT...HAVE DECIDED TO BUMP POPS UP MON-WED PDS.
&&
.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1242 PM CDT WED AUG 20 2014
ONGOING CONVECTION OVER NORTHEAST NEBRASKA HAS BEEN LIFTING NORTH
DURING THE MORNING AND THIS TREND IS EXPECTED TO CONTINUE INTO THE
AFTERNOON AS WARM FRONT MOVES NORTH TO ALONG THE NEBRASKA SOUTH
DAKOTA BORDER BY 00Z. SOME CHANCE OF THUNDERSTORMS AFTER 06Z AT
KOFK AS WEAK TROUGH MOVES INTO NORTH CENTRAL NEBRASKA BUT LESS
LIKELY AT KOMA AND KLNK WHERE SOME CAPPING EXPECTED. VFR
CONDITIONS WILL PREVAIL OUTSIDE OF THUNDERSTORM ACTIVITY.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...DEE
LONG TERM...DEE
AVIATION...FOBERT
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
633 PM EDT WED AUG 20 2014
.SYNOPSIS...
HOT AND HUMID WEATHER WILL PREVAIL OVER THE NEXT COUPLE OF DAYS
BEFORE SOME COOLING DURING THE WEEKEND AS A COLD FRONT MOVES
THROUGH. LOCAL RAIN CHANCES WILL DECREASE EARLY NEXT WEEK AS HIGH
PRESSURE BUILDS INTO THE REGION FROM THE NORTH.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
AS OF 6:30 PM WEDNESDAY...CONVECTION HAS FADED AREA-WIDE AND WITH
LITTLE IN THE WAY OF TRIGGERS TO RE-INITIATE STORM DEVELOPMENT
HAVE DROPPED POPS TO SLIGHT CHANCE FOR THE NEXT FEW HOURS...AND
DRY AFTER MIDNIGHT. GIVEN SPEED OF STORM AND SHOWER
DISSIPATION...MAY FURTHER REDUCE CHANCES TO NEAR NIL IN AN HOUR
OR SO. RELEVANT PORTION OF PREVIOUS DISCUSSION FOLLOWS:
DAYBREAK THURSDAY LOW/MID 70S MOST LOCATIONS WITH UPPER 70S TO
NEAR 80 CLOSER TO THE IMMEDIATE COAST AND ICW LOCALS.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
AS OF 315 PM WEDNESDAY...THIS PERIOD WILL BE MARKED BY A RETURN OF
SWELTERING HEAT AND HUMIDITY TO THE EASTERN CAROLINAS. AN UPPER
RIDGE OF HIGH PRESSURE CENTERED OVER THE GULF COAST WILL EXPAND
EASTWARD ON THU AS 500 MB HEIGHTS RISE OVER OUR CWA. 850 MB TEMPS
CLIMB TO 19-20C ON THU AND 20-21C ON FRI AS NORTHWEST FLOW ALOFT
RESULTS IN DOWNSLOPE ADIABATIC WARMING. EXPECT HIGHS ON THU/FRI TO
REACH THE MID TO UPPER 90S EVERYWHERE AWAY FROM THE IMMEDIATE
COAST. GIVEN THE LARGE VARIATIONS BETWEEN GFS/NAM DEWPOINTS
ATTM...HAVE OPTED FOR A GMOS/NAM BLEND THAT GIVES DEWPOINTS IN THE
LOW TO MID 70S. THIS YIELDS HEAT INDICES OF 100-105F ACROSS THE
AREA BOTH DAYS. THE MOST OPPRESSIVE HEAT WILL BE FELT ACROSS
NORTHEAST SOUTH CAROLINA...WHERE HEAT INDICES ARE EXPECTED TO
EXCEED HEAT ADVISORY CRITERIA OF 105F. I WILL RAISE A HEAT
ADVISORY FOR THU FOR ALL OF OUR SOUTH CAROLINA COUNTIES...EXCEPT
DILLON AND MARLBORO COUNTY. CONDITIONS MAY WARRANT A HEAT ADVISORY
FOR FRI AS WELL.
UPPER RIDGING ON THU WILL WORK TO SUPPRESS CONVECTION DURING PEAK
HEATING...AND THE LATEST GFS/NAM RUNS SHOW LITTLE TO NO ACTIVITY FOR
US DURING THE DAY. WILL STILL MAINTAIN SLIGHT CHC POPS DURING THE
AFTN HOURS AS MESOSCALE BOUNDARIES LIKE THE SEA BREEZE PROVIDE SOME
ENHANCED LIFT. MOST ACTIVITY WILL BE DISPLACED NORTH OF OUR CWA
ALONG WITH THE DEEPER MOISTURE. PWATS INCREASE TO AROUND 2.0 INCHES
ON FRI AHEAD OF AN APPROACHING BACKDOOR COLD FRONT. AN UPPER
DISTURBANCE EMBEDDED WITHIN THE NORTHWEST FLOW WILL ALSO MOVE
OVERHEAD LATE FRI. THIS WARRANTS CHC POPS FRI AFTN AND EVENING...
HIGHEST ACROSS THE CAPE FEAR AREA. SHEAR PROFILES ARE UNIMPRESSIVE
BOTH DAYS...BUT SOME DRY AIR ALOFT AND STEEP LOW-LEVEL LAPSE RATES
SUGGEST THAT AN ISOLATED DAMAGING WIND GUST CANNOT BE RULED OUT.
HIGH CAPE VALUES ENSURE THAT MOST STORMS WILL BE ACCOMPANIED BY
NUMEROUS CLOUD-TO-GROUND LIGHTNING STRIKES AS WELL. THE WEAK COLD
FRONT WILL PUSH THROUGH OUR CWA BY THE END OF THE PERIOD.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 3 AM WEDNESDAY...THE WEEKEND WILL BRING AN EASING OF THE HEAT
AND HUMIDITY AS THE FRONT STALLS NEAR THE REGION. THE WEATHER MAY
STAY RATHER UNSETTLED THOUGH AS THE DEEP LAYER MOISTURE IS SLOW TO
MAKE MUCH SOUTHERN PROGRESS. AS MID LEVEL RIDGE VERY SLOWLY CREEPS
TOWARDS THE AREA FROM THE WEST MONDAY AND TUESDAY WE SHOULD SEE LESS
DEEP MOISTURE AND THUS LOWER RAIN CHANCES. MEANWHILE THE HIGH STILL
BUILDING IN FROM THE NORTH WILL KEEP TEMPERATURES RATHER SEASONABLE
DESPITE THE BUILDING HEIGHTS ALOFT.
&&
.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...
AS OF 18Z...ANOTHER SUMMER DAY...MORE CONVECTION EXPECTED.
HOWEVER...LESS MOISTURE TO WORK WITH THAN THE PREVIOUS DAY. THE
LEVEL OF FREE CONVECTION IS STILL FAIRLY HIGH...SO EXPECT CONVECTION TO
FIRE LATE...AROUND 20Z LOOKS TO BE A GOOD BET. MOST OF IT WILL BE
FOCUSED NEAR THE COAST...WITH ISOLATED ACTIVITY INLAND. WILL STICK
WITH A TEMPO GROUP AS HRRR AND THE WRF MODEL DO HAVE DECENT COVERAGE
THE THE COAST. WINDS WILL SHIFT TO THE SOUTHEAST THIS AFTERNOON WITH
THE RESULTANT BOUNDARY. TONIGHT...MODERATE CONFIDENCE FOR PATCHY IFR
FOG WITH LIGHT WINDS.
EXTENDED OUTLOOK...CHC AFTERNOON/EVENING SHRA/TSRA THROUGH THE
SUNDAY. VFR MONDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 6:30 PM WEDNESDAY...NO CHANGES TO THE FORECAST WITH THE
LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS:
NO ADVISORIES OR CAUTION STATEMENTS WILL BE NEEDED FOR THE MARINE
FORECAST THROUGH EARLY WEDNESDAY...WITH SW WINDS 15 KT OR LESS IN
PLACE AND SEAS OF 2-3 FEET. SEAS ARE A MIX OF S WAVES 2 FT EVERY 4
SECONDS AND SE WAVES 1-1.5 FT EVERY 8-9 SECONDS. STEERING WINDS
COULD GUIDE STORMS TOWARD THE SE OVER THE NEAR SHORE WATERS...AND
GETTING A RADAR UPDATE BEFORE DISEMBARKING IS A GOOD IDEA THROUGH
DAYBREAK WEDNESDAY. HEAVY RAIN COULD REDUCE VSBYS TO 1NM AT TIMES.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 315 PM WEDNESDAY...WINDS OVER THE WATERS WILL BE PRIMARILY
SOUTHWEST THROUGH THE PERIOD...AOB 10 KTS ON THU BECOMING 10-15 KT
BY FRI MORNING. 2 FT SEAS DURING THU WILL BUILD TO 2-3 FT OVERNIGHT
THU AS THE GRADIENT TIGHTENS OFFSHORE. A BACKDOOR COLD FRONT WILL
SLOWLY DROP SOUTHWARD ON FRI...CROSSING OUR WATERS NEAR THE END OF
THE PERIOD. STRENGTHENING SOUTHWEST FLOW AHEAD OF THE FRONT DURING
FRI WILL PRODUCE 3 FT SEAS. SEAS WILL SUBSIDE A BIT OVERNIGHT FRI AS
WINDS BECOME NORTHWEST 5-10 KT FOLLOWING FROPA EARLY SAT MORNING.
LONG TERM /SATURDAY THROUGH SUNDAY/...
AS OF 3 AM WEDNESDAY...COLD FRONT TO LAZILY MOVE SOUTH ACROSS THE
ZONES ON SATURDAY. WIND SPEEDS WILL REMAIN VERY SLACK THROUGH FROPA
SO AS WIND DIRECTION TURNS FROM OFFSHORE TO ONSHORE SEAS WILL LIKELY
STAY AT THE 2 FT MARK OR LOWER. HIGH PRESSURE BUILDING IN FROM THE
NORTH AND EAST ON SUNDAY WILL ADD 5 KT OF WIND FOR A HIGHER CATEGORY
FORECAST. 3 FT SEAS SHOULD THUS RETURN TO MOST ZONES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...HEAT ADVISORY FROM NOON TO 6 PM EDT THURSDAY FOR SCZ023-032-
033-039-053>056.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BJR
NEAR TERM...MJC
SHORT TERM...BJR
LONG TERM...MBB
AVIATION...MJC/DL
MARINE...MJC/REK/MBB/BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
316 PM EDT WED AUG 20 2014
.SYNOPSIS...
HOT AND HUMID WEATHER WILL PREVAIL OVER THE NEXT COUPLE DAYS
BEFORE SOME COOLING DURING THE WEEKEND AS A FRONT MOVES THROUGH.
LOCAL RAIN CHANCES WILL DECREASE EARLY NEXT WEEK AS HIGH PRESSURE
BUILDS INTO THE REGION FROM THE NORTH.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
AS OF 315 PM WEDNESDAY...WARM H5 TEMPS OF -5 TO -6 ARE SQUELCHING
THE PROPENSITY FOR TOWERS TO ASCEND VERY MUCH ABOVE 45000
FEET...BUT A SNAKE PIT OF SURFACE BOUNDARIES FROM OUTFLOWS...A SEA
BREEZE LINE AND A STATIONARY FRONTAL BOUNDARY COULD BRIEFLY PULSE
CELLS CLOSER TO SEVERE LIMITS IN ANY STRONG BOUNDARY COLLISION.
PWAT VALUES REMAIN ELEVATED ACROSS NE SC/SE NC...ALONG WITH HIGH
DEWPOINTS NEAR THE COAST AND AN APPROACHING UPPER TROUGH EVIDENT
IN VAPOR MOVIES. THESE FEATURES MAY SUSTAIN CONVECTION THROUGH
MUCH OF EVENING DESPITE A DIURNAL COOLING TREND AFTER DUSK. AT THE
SFC A WEAK LOW PRESSURE AREA WILL RESIDE OVER INLAND ZONES AND
SOME DEGREE OF LOW-LEVEL CONVERGENCE WILL REMAIN AVAILABLE AS
WELL. LOCALIZED FLOODING APPEARS THE MAIN THREAT AT THIS
TIME...THOUGH ANY COLLIDING BOUNDARIES COULD SET THE STAGE FOR
STRONG WIND GUSTS ONCE THE ENSUING UPDRAFT COLLAPSES.
DAYBREAK THURSDAY LOW/MID 70S MOST LOCATIONS WITH UPPER 70S TO
NEAR 80 CLOSER TO THE IMMEDIATE COAST AND ICW LOCALS.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
AS OF 315 PM WEDNESDAY...THIS PERIOD WILL BE MARKED BY A RETURN OF
SWELTERING HEAT AND HUMIDITY TO THE EASTERN CAROLINAS. AN UPPER
RIDGE OF HIGH PRESSURE CENTERED OVER THE GULF COAST WILL EXPAND
EASTWARD ON THU AS 500 MB HEIGHTS RISE OVER OUR CWA. 850 MB TEMPS
CLIMB TO 19-20C ON THU AND 20-21C ON FRI AS NORTHWEST FLOW ALOFT
RESULTS IN DOWNSLOPE ADIABATIC WARMING. EXPECT HIGHS ON THU/FRI TO
REACH THE MID TO UPPER 90S EVERYWHERE AWAY FROM THE IMMEDIATE
COAST. GIVEN THE LARGE VARIATIONS BETWEEN GFS/NAM DEWPOINTS
ATTM...HAVE OPTED FOR A GMOS/NAM BLEND THAT GIVES DEWPOINTS IN THE
LOW TO MID 70S. THIS YIELDS HEAT INDICES OF 100-105F ACROSS THE
AREA BOTH DAYS. THE MOST OPPRESSIVE HEAT WILL BE FELT ACROSS
NORTHEAST SOUTH CAROLINA...WHERE HEAT INDICES ARE EXPECTED TO
EXCEED HEAT ADVISORY CRITERIA OF 105F. I WILL RAISE A HEAT
ADVISORY FOR THU FOR ALL OF OUR SOUTH CAROLINA COUNTIES...EXCEPT
DILLON AND MARLBORO COUNTY. CONDITIONS MAY WARRANT A HEAT ADVISORY
FOR FRI AS WELL.
UPPER RIDGING ON THU WILL WORK TO SUPPRESS CONVECTION DURING PEAK
HEATING...AND THE LATEST GFS/NAM RUNS SHOW LITTLE TO NO ACTIVITY FOR
US DURING THE DAY. WILL STILL MAINTAIN SLIGHT CHC POPS DURING THE
AFTN HOURS AS MESOSCALE BOUNDARIES LIKE THE SEA BREEZE PROVIDE SOME
ENHANCED LIFT. MOST ACTIVITY WILL BE DISPLACED NORTH OF OUR CWA
ALONG WITH THE DEEPER MOISTURE. PWATS INCREASE TO AROUND 2.0 INCHES
ON FRI AHEAD OF AN APPROACHING BACKDOOR COLD FRONT. AN UPPER
DISTURBANCE EMBEDDED WITHIN THE NORTHWEST FLOW WILL ALSO MOVE
OVERHEAD LATE FRI. THIS WARRANTS CHC POPS FRI AFTN AND EVENING...
HIGHEST ACROSS THE CAPE FEAR AREA. SHEAR PROFILES ARE UNIMPRESSIVE
BOTH DAYS...BUT SOME DRY AIR ALOFT AND STEEP LOW-LEVEL LAPSE RATES
SUGGEST THAT AN ISOLATED DAMAGING WIND GUST CANNOT BE RULED OUT.
HIGH CAPE VALUES ENSURE THAT MOST STORMS WILL BE ACCOMPANIED BY
NUMEROUS CLOUD-TO-GROUND LIGHTNING STRIKES AS WELL. THE WEAK COLD
FRONT WILL PUSH THROUGH OUR CWA BY THE END OF THE PERIOD.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 3 AM WEDNESDAY...THE WEEKEND WILL BRING AN EASING OF THE HEAT
AND HUMIDITY AS THE FRONT STALLS NEAR THE REGION. THE WEATHER MAY
STAY RATHER UNSETTLED THOUGH AS THE DEEP LAYER MOISTURE IS SLOW TO
MAKE MUCH SOUTHERN PROGRESS. AS MID LEVEL RIDGE VERY SLOWLY CREEPS
TOWARDS THE AREA FROM THE WEST MONDAY AND TUESDAY WE SHOULD SEE LESS
DEEP MOISTURE AND THUS LOWER RAIN CHANCES. MEANWHILE THE HIGH STILL
BUILDING IN FROM THE NORTH WILL KEEP TEMPERATURES RATHER SEASONABLE
DESPITE THE BUILDING HEIGHTS ALOFT.
&&
.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
AS OF 18Z...ANOTHER SUMMER DAY...MORE CONVECTION EXPECTED.
HOWEVER...LESS MOISTURE TO WORK WITH THAN THE PREVIOUS DAY. THE
LEVEL OF FREE CONVECTION IS STILL FAIRLY HIGH...SO EXPECT CONVECTION TO
FIRE LATE...AROUND 20Z LOOKS TO BE A GOOD BET. MOST OF IT WILL BE
FOCUSED NEAR THE COAST...WITH ISOLATED ACTIVITY INLAND. WILL STICK
WITH A TEMPO GROUP AS HRRR AND THE WRF MODEL DO HAVE DECENT COVERAGE
THE THE COAST. WINDS WILL SHIFT TO THE SOUTHEAST THIS AFTERNOON WITH
THE RESULTANT BOUNDARY. TONIGHT...MODERATE CONFIDENCE FOR PATCHY IFR
FOG WITH LIGHT WINDS.
EXTENDED OUTLOOK...CHC AFTERNOON/EVENING SHRA/TSRA THROUGH THE
SUNDAY. VFR MONDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 315 PM WEDNESDAY...NO ADVISORIES OR CAUTION STATEMENTS WILL BE
NEEDED FOR THE MARINE FORECAST THROUGH EARLY WEDNESDAY...WITH SW
WINDS 15 KT OR LESS IN PLACE AND SEAS OF 2-3 FEET. SEAS ARE A MIX
OF S WAVES 2 FT EVERY 4 SECONDS AND SE WAVES 1-1.5 FT EVERY 8-9
SECONDS. STEERING WINDS COULD GUIDE STORMS TOWARD THE SE OVER THE
NEAR SHORE WATERS...AND GETTING A RADAR UPDATE BEFORE DISEMBARKING
IS A GOOD IDEA THROUGH DAYBREAK WEDNESDAY. HEAVY RAIN COULD REDUCE
VSBYS TO 1NM AT TIMES.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 315 PM WEDNESDAY...WINDS OVER THE WATERS WILL BE PRIMARILY
SOUTHWEST THROUGH THE PERIOD...AOB 10 KTS ON THU BECOMING 10-15 KT
BY FRI MORNING. 2 FT SEAS DURING THU WILL BUILD TO 2-3 FT OVERNIGHT
THU AS THE GRADIENT TIGHTENS OFFSHORE. A BACKDOOR COLD FRONT WILL
SLOWLY DROP SOUTHWARD ON FRI...CROSSING OUR WATERS NEAR THE END OF
THE PERIOD. STRENGTHENING SOUTHWEST FLOW AHEAD OF THE FRONT DURING
FRI WILL PRODUCE 3 FT SEAS. SEAS WILL SUBSIDE A BIT OVERNIGHT FRI AS
WINDS BECOME NORTHWEST 5-10 KT FOLLOWING FROPA EARLY SAT MORNING.
LONG TERM /SATURDAY THROUGH SUNDAY/...
AS OF 3 AM WEDNESDAY...COLD FRONT TO LAZILY MOVE SOUTH ACROSS THE
ZONES ON SATURDAY. WIND SPEEDS WILL REMAIN VERY SLACK THROUGH FROPA
SO AS WIND DIRECTION TURNS FROM OFFSHORE TO ONSHORE SEAS WILL LIKELY
STAY AT THE 2 FT MARK OR LOWER. HIGH PRESSURE BUILDING IN FROM THE
NORTH AND EAST ON SUNDAY WILL ADD 5 KT OF WIND FOR A HIGHER CATEGORY
FORECAST. 3 FT SEAS SHOULD THUS RETURN TO MOST ZONES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...HEAT ADVISORY FROM NOON TO 6 PM EDT THURSDAY FOR SCZ023-032-
033-039-053>056.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...MJC
SHORT TERM...BJR
LONG TERM...MBB
AVIATION...MJC/DL
MARINE...MJC/BJR/MBB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
305 PM EDT WED AUG 20 2014
.SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES IN NORTHWEST FLOW
ALOFT WILL CROSS THE REGION THIS WEEK. A BACK DOOR COLD FRONT IS
FORECAST TO SLIP INTO THE AREA OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 220 PM WEDNESDAY...
THE OVER ALL WEATHER PATTERN STILL CONSISTS OF RELATIVELY WEAK
NORTHWESTERLY FLOW ALOFT AND A BROAD TROUGH AT THE SURFACE. ONE
UPPER DISTURBANCE...ATTENDANT TO A SHORTWAVE CROSSING THE
APPALACHIANS...CLIPPED THE NORTHERN HALF OF THE AREA THIS
MORNING...BUT THE ASSOCIATED CONVECTION DIED AS IT MOVED INTO THE
TRIAD. A TRAILING DISTURBANCE IS EVIDENT IN WATER VAPOR AND RAP H5
ANALYSIS OVER SOUTHWEST VA AND NORTHEAST TN...AND IS PROGGED TO CROSS
THE AREA THIS EVENING. THE BEST INSTABILITY HAS DEVELOPED FROM THE
SANDHILLS TO THE WESTERN PIEDMONT WHERE HEATING WAS UNINHIBITED BY
MORNING STRATUS. WITHIN THE INSTABILITY AXIS...A ZONE OF LOW-LEVEL
CONVERGENCE ACROSS THE SANDHILLS HAS INITIATED SOME SLOW MOVING
SHOWERS AND ISOLATED STORMS FROM RAEFORD TO THE SOUTHEAST. THE
APPROACHING DISTURBANCE SHOULD HELP TO INITIATE SOME ADDITIONAL
CONVECTION THIS AFTERNOON...THOUGH THE HRRR HAS YET TO LATCH ONTO
ANY TREND IN THE NEAR TERM. EXPECT SHOWERS AND STORMS ARE MORE
LIKELY FROM THE TRIAD DOWN TO FAYETTEVILLE...WITH JUST A SLIGHT
CHANCE FROM THO TRIANGLE NORTHEAST. IF CONVECTION DOES FIRE...A
RIBBON OF 30KT EFFECTIVE DEEP SHEAR AT THE BASE OF THE UPPER TROUGH
WILL SUPPORT SOME STRONGER CLUSTERS OF STORMS CAPABLE OF PRODUCING
SMALL HAIL AND ISOLATED DAMAGING WIND GUSTS.
TONIGHT...FORECAST SOUNDINGS SHOW SOME STEEP L;APSE RATES ABOVE THE
NOCTURNAL INVERSION...BUT THERE ISNT A CLEAR MECHANISM TO FORCE ANY
PARCELS OVERNIGHT...SO WILL LEAVE POPS OUT OF THE FORECAST AFTER
03Z. FORECAST SOUNDINGS ALSO SHOW LESS LOW-LEVEL MOISTENING TONIGHT
WITHOUT THE NORTHEASTERLY FLOW WE`VE SEEN THE LAST COUPLE OF
NIGHT...AND THEREFORE LESS POTENTIAL FOR STRATUS. LOWS IN THE UPPER
60S AND LOWER 70S.
&&
.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 305 PM WEDNESDAY...
MID-LEVEL RIDGING BUILDS OVER THE DEEP SOUTH ON THURSDAY...LEADING
TO WEAK HEIGHT RISES OVER THE CAROLINAS AND H85 TEMPS SURPASSING
20C. FORECAST SOUNDINGS SHOW DEEP MIXING WITH WESTERLY FLOW...AND
DRY ADIABATIC MIXING YIELDS HIGHS WILL INTO THE 90S...WITH A
CONSENSUS OF 93-97. MIXING SHOULD ALSO HELP KNOCK DEWPOINTS BACK A
FEW DEGREES...HELPING KEEP HEAT INDICES AT 100F OR LESS. MLCAPE OF
AROUND 1000 J/KG IS FORECAST...BUT FORCING APPEARS TO BE LIMITED TO
THE RESIDUAL/THERMAL TROUGH WHICH SETS UP OVER THE EASTERN PIEDMONT.
WILL KEEP POPS AS ISOLATED UNLESS. LOWS THURSDAY NIGHT IN THE LOWER
70S.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 145 PM WEDNESDAY...
THE INITIAL LONG TERM PERIOD REMAINS CHARACTERIZED BY A BUILDING
UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY WITH AN UPPER
TROUGH/CLOSED LOW OFF THE NORTHEAST COAST...LEAVING CENTRAL NC UNDER
NORTHWEST UPPER FLOW INTO EARLY NEXT WEEK. A BACKDOOR FRONT WILL
MOVE ACROSS THE AREA LATE FRIDAY THROUGH SATURDAY...WHICH WILL
PRODUCE OUR BEST CHANCE OF PRECIPITATION DUE TO LOW LEVEL LIFT FROM
THE COOL AIR ADVECTION POTENTIALLY AIDED BY MODEST UPPER LEVEL
SUPPORT. OUTSIDE OF THE SLIGHTLY INCREASED CONFIDENCE IN THIS EARLY
WEEKEND PERIOD... PRECIP CHANCES HINGE ON MESOSCALE DISTURBANCES
ALOFT WITHIN THE NORTHWEST FLOW...WHICH ARE JUST ABOUT IMPOSSIBLE TO
FORECAST THIS FAR IN ADVANCE. AS SUCH...WILL MAINTAIN SMALL CHANCE
POPS THROUGH MONDAY...AFTER WHICH THE UPPER RIDGE AXIS SHIFTS EAST
ENOUGH TO DAMPEN PRECIP CHANCES.
HEIGHTS AND LOW LEVEL THICKNESSES PEAKING FRIDAY ARE INDICATIVE OF
HIGHS REACHING THE MID 90S OVER MUCH OF THE AREA. THESE HEIGHTS FALL
AS THE UPPER TROF DEEPENS ALONG THE EAST COAST CONCURRENT WITH COOL
AIR ADVECTION BY LATER SATURDAY IN UNIFORM LOW LEVEL NORTHEAST FLOW.
HIGHS WILL BE IN TRANSITION SATURDAY...FROM MID 80S NORTH TO 90
SOUTH...AND BOTTOMING OUT IN THE UPPER 70S TO LOWER 80S SUNDAY AND
MONDAY AS DAMMING SETTLES DOWN THE EAST COAST. MORNING LOWS
INITIALLY IN THE LOWER 70S SATURDAY MORNING WILL GRADUALLY FALL INTO
THE LOW TO MID 60S BY TUESDAY MORNING.
THE UPPER RIDGE AXIS WILL SHIFT EAST ON TUESDAY...WITH DRIER AIR AND
GRADUAL MODIFICATION OF THE AIR MASS IN PLACE. HIGHS TUESDAY WILL BE
MOSTLY IN THE LOW TO MID 80S...WARMING TO MOSTLY MID 80S ON
WEDNESDAY.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 145 PM WEDNESDAY...
MORNING STRATUS LIFTED TO VFR MOST PLACES PRIOR TO 17Z...THOUGH A
FEW LOCATIONS ARE STILL REPORTING MVFR CEILINGS. INCREASING
INSTABILITY AND AN APPROACHING WEAK UPPER DISTURBANCE SHOULD LEAD TO
SCATTERED SHOWERS AND STORMS AGAIN THIS AFTERNOON...THOUGH THERE IS
STILL NEAR TERM UNCERTAINTY AS TO WHERE SHOWERS AND STORMS WILL BE
FOCUSED. BASED ON LATEST ANALYSIS IT APPEARS AREA FROM KGSO/KINT
TO KFAY WILL BE MOST FAVORED...AND THERE ARE ALREADY SOME SHOWERS
DEVELOPING JUST TO THE SOUTHWEST OF KFAY. OUTSIDE OF THE SHOWERS
AND/OR STORMS...VFR CONDITIONS ARE EXPECTED TO PREVAIL.
TONIGHT...LIGHT WINDS AND SOME CLEARING MAY LEAD TO LOW CLOUDS AND
FOG BY THURSDAY MORNING...THOUGH FORECAST SOUNDINGS DONT SHOW AS
MUCH POTENTIAL AS IN PREVIOUS NIGHTS. IF LOW CLOUDS OR FOG
DEVELOP...IFR/LIFR CONDITIONS WOULD BE ANTICIPATED.
OUTLOOK... EARLY MORNING STRATUS/FOG...ALONG WITH AFTERNOON SHOWERS
AND STORMS WILL BE POSSIBLE EACH DAY THIS WEEK. A BACKDOOR COLD
FRONT WILL MOVE INTO THE AREA OVER THE WEEKEND...WHICH MAY BRING
ANOTHER PERIOD UNSETTLED WEATHER FOR PORTIONS OF THE AREA.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLS
NEAR TERM...BLS
SHORT TERM...BLS
LONG TERM...MLM
AVIATION...BLS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
220 PM EDT WED AUG 20 2014
.SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES IN NORTHWEST FLOW
ALOFT WILL CROSS THE REGION THIS WEEK. A BACK DOOR COLD FRONT IS
FORECAST TO SLIP INTO THE AREA OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 220 PM WEDNESDAY...
THE OVER ALL WEATHER PATTERN STILL CONSISTS OF RELATIVELY WEAK
NORTHWESTERLY FLOW ALOFT AND A BROAD TROUGH AT THE SURFACE. ONE
UPPER DISTURBANCE...ATTENDANT TO A SHORTWAVE CROSSING THE
APPALACHIANS...CLIPPED THE NORTHERN HALF OF THE AREA THIS
MORNING...BUT THE ASSOCIATED CONVECTION DIED AS IT MOVED INTO THE
TRIAD. A TRAILING DISTURBANCE IS EVIDENT IN WATER VAPOR AND RAP H5
ANALYSIS OVER SOUTHWEST VA AND NORTHEAST TN...AND IS PROGGED TO CROSS
THE AREA THIS EVENING. THE BEST INSTABILITY HAS DEVELOPED FROM THE
SANDHILLS TO THE WESTERN PIEDMONT WHERE HEATING WAS UNINHIBITED BY
MORNING STRATUS. WITHIN THE INSTABILITY AXIS...A ZONE OF LOW-LEVEL
CONVERGENCE ACROSS THE SANDHILLS HAS INITIATED SOME SLOW MOVING
SHOWERS AND ISOLATED STORMS FROM RAEFORD TO THE SOUTHEAST. THE
APPROACHING DISTURBANCE SHOULD HELP TO INITIATE SOME ADDITIONAL
CONVECTION THIS AFTERNOON...THOUGH THE HRRR HAS YET TO LATCH ONTO
ANY TREND IN THE NEAR TERM. EXPECT SHOWERS AND STORMS ARE MORE
LIKELY FROM THE TRIAD DOWN TO FAYETTEVILLE...WITH JUST A SLIGHT
CHANCE FROM THO TRIANGLE NORTHEAST. IF CONVECTION DOES FIRE...A
RIBBON OF 30KT EFFECTIVE DEEP SHEAR AT THE BASE OF THE UPPER TROUGH
WILL SUPPORT SOME STRONGER CLUSTERS OF STORMS CAPABLE OF PRODUCING
SMALL HAIL AND ISOLATED DAMAGING WIND GUSTS.
TONIGHT...FORECAST SOUNDINGS SHOW SOME STEEP L;APSE RATES ABOVE THE
NOCTURNAL INVERSION...BUT THERE ISNT A CLEAR MECHANISM TO FORCE ANY
PARCELS OVERNIGHT...SO WILL LEAVE POPS OUT OF THE FORECAST AFTER
03Z. FORECAST SOUNDINGS ALSO SHOW LESS LOW-LEVEL MOISTENING TONIGHT
WITHOUT THE NORTHEASTERLY FLOW WE`VE SEEN THE LAST COUPLE OF
NIGHT...AND THEREFORE LESS POTENTIAL FOR STRATUS. LOWS IN THE UPPER
60S AND LOWER 70S.
&&
.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 245 AM WEDNESDAY...
LITTLE CHANGE ON THE SYNOPTIC PATTERN ON THURSDAY. CENTRAL NC WILL
REMAIN POISED TO SEE VORT DISTURBANCES EMBEDDED IN THE NW FLOW ALOFT
AS THE UPPER LOW OVER THE GREAT LAKES WEAKENS THROUGH THE DAY AS IT
MOVES EAST INTO THE NE US. AT THIS TIME...CAN NOT FIND A DISCERNIBLE
FEATURE THAT WOULD SUPPORT MORE THAN ISOLATED SLIGHT CHANCE POPS
THURSDAY/THURSDAY NIGHT...IN FACT...500MB HEIGHTS ACTUALLY INCREASE
OVER THE AREA ON THURSDAY...WITH ASSOCIATED SUBSIDENCE/WARMING ALOFT
POSSIBLY SUPPRESSING CONVECTION TO A POINT WHERE IT COULD END UP
BEING ONE OF THE LEAST CONVECTIVELY ACTIVE DAYS OF THE WEEK.
AS FAR AS TEMPERATURES...BOTH THE EC AND GFS INDICATE H8
TEMPERATURES WILL WARM TO 22C...WHICH SHOULD SUPPORT HIGHS THURSDAY
SOLIDLY IN THE MID 90S. LOWS THURSDAY NIGHT IN THE LOWER 70S.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 145 PM WEDNESDAY...
THE INITIAL LONG TERM PERIOD REMAINS CHARACTERIZED BY A BUILDING
UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY WITH AN UPPER
TROUGH/CLOSED LOW OFF THE NORTHEAST COAST...LEAVING CENTRAL NC UNDER
NORTHWEST UPPER FLOW INTO EARLY NEXT WEEK. A BACKDOOR FRONT WILL
MOVE ACROSS THE AREA LATE FRIDAY THROUGH SATURDAY...WHICH WILL
PRODUCE OUR BEST CHANCE OF PRECIPITATION DUE TO LOW LEVEL LIFT FROM
THE COOL AIR ADVECTION POTENTIALLY AIDED BY MODEST UPPER LEVEL
SUPPORT. OUTSIDE OF THE SLIGHTLY INCREASED CONFIDENCE IN THIS EARLY
WEEKEND PERIOD... PRECIP CHANCES HINGE ON MESOSCALE DISTURBANCES
ALOFT WITHIN THE NORTHWEST FLOW...WHICH ARE JUST ABOUT IMPOSSIBLE TO
FORECAST THIS FAR IN ADVANCE. AS SUCH...WILL MAINTAIN SMALL CHANCE
POPS THROUGH MONDAY...AFTER WHICH THE UPPER RIDGE AXIS SHIFTS EAST
ENOUGH TO DAMPEN PRECIP CHANCES.
HEIGHTS AND LOW LEVEL THICKNESSES PEAKING FRIDAY ARE INDICATIVE OF
HIGHS REACHING THE MID 90S OVER MUCH OF THE AREA. THESE HEIGHTS FALL
AS THE UPPER TROF DEEPENS ALONG THE EAST COAST CONCURRENT WITH COOL
AIR ADVECTION BY LATER SATURDAY IN UNIFORM LOW LEVEL NORTHEAST FLOW.
HIGHS WILL BE IN TRANSITION SATURDAY...FROM MID 80S NORTH TO 90
SOUTH...AND BOTTOMING OUT IN THE UPPER 70S TO LOWER 80S SUNDAY AND
MONDAY AS DAMMING SETTLES DOWN THE EAST COAST. MORNING LOWS
INITIALLY IN THE LOWER 70S SATURDAY MORNING WILL GRADUALLY FALL INTO
THE LOW TO MID 60S BY TUESDAY MORNING.
THE UPPER RIDGE AXIS WILL SHIFT EAST ON TUESDAY...WITH DRIER AIR AND
GRADUAL MODIFICATION OF THE AIR MASS IN PLACE. HIGHS TUESDAY WILL BE
MOSTLY IN THE LOW TO MID 80S...WARMING TO MOSTLY MID 80S ON
WEDNESDAY.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 145 PM WEDNESDAY...
MORNING STRATUS LIFTED TO VFR MOST PLACES PRIOR TO 17Z...THOUGH A
FEW LOCATIONS ARE STILL REPORTING MVFR CEILINGS. INCREASING
INSTABILITY AND AN APPROACHING WEAK UPPER DISTURBANCE SHOULD LEAD TO
SCATTERED SHOWERS AND STORMS AGAIN THIS AFTERNOON...THOUGH THERE IS
STILL NEAR TERM UNCERTAINTY AS TO WHERE SHOWERS AND STORMS WILL BE
FOCUSED. BASED ON LATEST ANALYSIS IT APPEARS AREA FROM KGSO/KINT
TO KFAY WILL BE MOST FAVORED...AND THERE ARE ALREADY SOME SHOWERS
DEVELOPING JUST TO THE SOUTHWEST OF KFAY. OUTSIDE OF THE SHOWERS
AND/OR STORMS...VFR CONDITIONS ARE EXPECTED TO PREVAIL.
TONIGHT...LIGHT WINDS AND SOME CLEARING MAY LEAD TO LOW CLOUDS AND
FOG BY THURSDAY MORNING...THOUGH FORECAST SOUNDINGS DONT SHOW AS
MUCH POTENTIAL AS IN PREVIOUS NIGHTS. IF LOW CLOUDS OR FOG
DEVELOP...IFR/LIFR CONDITIONS WOULD BE ANTICIPATED.
OUTLOOK... EARLY MORNING STRATUS/FOG...ALONG WITH AFTERNOON SHOWERS
AND STORMS WILL BE POSSIBLE EACH DAY THIS WEEK. A BACKDOOR COLD
FRONT WILL MOVE INTO THE AREA OVER THE WEEKEND...WHICH MAY BRING
ANOTHER PERIOD UNSETTLED WEATHER FOR PORTIONS OF THE AREA.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLS
NEAR TERM...BLS
SHORT TERM...CBL
LONG TERM...MLM
AVIATION...BLS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
136 PM EDT WED AUG 20 2014
.SYNOPSIS...
HOT AND HUMID WEATHER WILL PREVAIL OVER THE NEXT SEVERAL DAYS
BEFORE SOME COOLING DURING THE WEEKEND AS A FRONT MOVES THROUGH.
LOCAL RAIN CHANCES WILL DECREASE EARLY NEXT WEEK AS HIGH PRESSURE
BUILDS INTO THE REGION FROM THE NORTH.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 135 PM WEDNESDAY...UPDATED THE LAND FORECASTS TO INCREASE
POP VALUES ACROSS THE WARNING AREA THROUGH THE AFTERNOON INTO
EARLY EVENING BASED ON RADAR TRENDS. ORIENTATION OF A WIND
CONVERGENCE BOUNDARY ALIGNED NEARLY ALONG THE PREVAILING STORM
MOTION IS LEADING TO TRAINING OF CELLS IN BRUNSWICK COUNTY AND
PORTIONS OF INLAND NC. FLOOD ADVISORIES WILL REMAIN POSSIBLE
THROUGH EVENING DUE TO HIGH PWAT CONTENT AND POTENTIAL FOR
TORRENTIAL EPISODES OF RAINFALL. THE PREVIOUS DISCUSSION FOLLOWS.
HIGH PRECIPITABLE WATER CONTENT BETWEEN 1.75 AND 1.85 INCHES
REMAINS LOADED IN THE COLUMN CURRENTLY AS REVEALED IN 12Z RAOBS
DATA FROM MHX/CHS. THE POTENT UPPER SWIRL YESTERDAY THAT MOVED
OFFSHORE LAST NIGHT...PUSHED A SURFACE TROUGH OVER THE COASTAL
WATERS EARLIER THIS MORNING. NO APPRECIABLE AIR MASS CHANGE IN
WAKE OF THIS FEATURE EXCEPT THAT DEWPOINTS REMAIN HIGHEST ALONG
THE COAST WHILE TAPERING INLAND AND A LIGHT W-NW WIND ACROSS
INLAND AREAS.
SIMILAR TO MON/TUE...PLENTIFUL SUNSHINE WILL ENSURE LOW-LEVEL
INSTABILITY WILL INCREASE INTO AFTERNOON IN A MOIST COLUMN. OF
SOME CONCERN IS THAT PROJECTED STEERING WINDS WILL CARRY
DEVELOPING AFTERNOON CONVECTION DIRECTLY PERPENDICULAR INTO A
ROBUST SEA-BREEZE BOUNDARY. THE LOW-LEVEL WIND FLOW APPEARS POISED
TO KEEP THIS MARINE BOUNDARY FASTENED CLOSE TO THE COAST...WHILE
UPPER WINDS GUIDE ACTIVITY TO THE BEACHES AND COASTAL INTERIOR
LATER TODAY. VAPOR ANALYSIS SHOWS SHORT-WAVE ENERGY IMPINGING THE
SOUTHERN AND CENTRAL APPALACHIANS PRESENTLY...WHICH TIMING-WISE IS
SET TO ENTER OUR NECK OF THE WOODS INTO OR JUST AFTER PEAK HEAT
BUILD-UP...LIKELY SPARKING STORMS LATE AFTERNOON THROUGH EVENING.
APPARENT TEMPS/HEAT INDICES AROUND 100 ACROSS NC AND 101-104 OVER
OUR SC INTERIOR LOCATIONS TODAY.
&&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM WEDNESDAY...THURSDAY WILL BRING UNSEASONABLE HEAT AND
HUMIDITY. A LATE DAY SHORTWAVE PASSING BY TO OUR NORTH COULD FAVOR
NORTHERN ZONES FOR SCATTERED CONVECTION WHILE ISOLATED CONVECTION
EXPECTED ALON THE SEABREEZE IN SOUTH CAROLINA. THE PIEDMONT TROUGH
WILL BE DISPLACED UNUSUALLY CLOSE TO THE COAST WHICH AND THIS SHOULD
MINIMIZE CONVECTION CHANCES OVER INLAND ZONES. SHEAR AND MOISTURE
PROFILES NOT INDICATIVE OF MUCH OF A SEVERE THREAT BUT STORMS WILL
BE CAPABLE OF WET MICROBURSTS AS WELL AS SOME HIGH LIGHTNING RATES.
STORMS MAY BE CLOSE BY TO OUR NORTH TOWARDS FRIDAY MORNING AS A
BACKDOOR COLD FRONT APPROACHES. NORTHWESTERLY MID LEVEL FLOW
STRENGTHENS ON FRIDAY AS THIS COLD FRONT CONTINUES ITS APPROACH. A
NW FLOW SQUALL LINE OF FORCED CONVECTION APPEARS POSSIBLE IF NOT
DOWNRIGHT INDICATED BY THE WRF. THE GFS IS SLOWER AND GENTLER WITH
ITS DEPICTIONS OF THE UPPER VORT AS WELL AS SURFACE BOUNDARY ARRIVAL
AND IS NOT AS SUGGESTIVE OF POSSIBLE STRONG STORMS ON FRIDAY.
INTERESTINGLY BOTH MODELS` MOS STRINGS NOW SHOW FRIDAY AFTERNOON AS
HOT IF NOT HOTTER THAN THURSDAY. FORECAST HAS BEEN ADJUSTED
ACCORDINGLY. NOW BOTH AFTERNOONS MAY FEATURE A MAX HEAT INDEX OF
AROUND 100 DEGREES OVER NRN ZONES TO 105 OR BETTER ALONG SC COASTAL
ZONES WHERE THE WARMEST TEMPS AND HIGHEST DEWPOINTS ARE JUXTAPOSED.
HEAT ADVISORY POSSIBLE FOR THOSE LATTER AREAS.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 3 AM WEDNESDAY...THE WEEKEND WILL BRING AN EASING OF THE HEAT
AND HUMIDITY AS THE FRONT STALLS NEAR THE REGION. THE WEATHER MAY
STAY RATHER UNSETTLED THOUGH AS THE DEEP LAYER MOISTURE IS SLOW TO
MAKE MUCH SOUTHERN PROGRESS. AS MID LEVEL RIDGE VERY SLOWLY CREEPS
TOWARDS THE AREA FROM THE WEST MONDAY AND TUESDAY WE SHOULD SEE LESS
DEEP MOISTURE AND THUS LOWER RAIN CHANCES. MEANWHILE THE HIGH STILL
BUILDING IN FROM THE NORTH WILL KEEP TEMPERATURES RATHER SEASONABLE
DESPITE THE BUILDING HEIGHTS ALOFT.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 18Z...ANOTHER SUMMER DAY...MORE CONVECTION EXPECTED.
HOWEVER...LESS MOISTURE TO WORK WITH THAN THE PREVIOUS DAY. THE
LEVEL OF FREE CONVECTION IS STILL FAIRLY HIGH...SO EXPECT CONVECTION TO
FIRE LATE...AROUND 20Z LOOKS TO BE A GOOD BET. MOST OF IT WILL BE
FOCUSED NEAR THE COAST...WITH ISOLATED ACTIVITY INLAND. WILL STICK
WITH A TEMPO GROUP AS HRRR AND THE WRF MODEL DO HAVE DECENT COVERAGE
THE THE COAST. WINDS WILL SHIFT TO THE SOUTHEAST THIS AFTERNOON WITH
THE RESULTANT BOUNDARY. TONIGHT...MODERATE CONFIDENCE FOR PATCHY IFR
FOG WITH LIGHT WINDS.
EXTENDED OUTLOOK...CHC AFTERNOON/EVENING SHRA/TSRA THROUGH THE
SUNDAY. VFR MONDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 135 AM WEDNESDAY...WEAK MEANDERING BOUNDARY ACROSS THE
NORTHERN PORTIONS OF THE ILM WATERS...WILL REVERT BACK TO NORTH OF
THE WATERS THIS AFTN AND TONIGHT. WILL MAINLY HAVE TO DEAL WITH
WIND DIRECTION CHANGES AS A RESULT...WITH OVERALL WIND SPEEDS 10
KT OR LESS DUE TO LACK OF ANY DECENT SFC PG. SIGNIFICANT SEAS WILL
RUN UP TO 3 FT...AND MAINLY COMPRISED OF WIND DRIVEN WAVES AT 5 TO
6 SECOND PERIODS. AN UNDERLYING 1-2 FOOT PSEUDO GROUND SWELL AT 7+
SECOND PERIODS WILL CONTINUE THRU THIS PERIOD.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 3 AM WEDNESDAY...PIEDMONT THROUGH WILL BE CLOSER TO THE COAST
THAN NORMAL ON THURSDAY KEEPING THE GRADIENT ACROSS THE WATERS VERY
LIGHT...CAPPED AT JUST 10 KTS WITH SOME INHERENT VARIABILITY
POSSIBLE IN DIRECTION. NO REAL SWELL TO SPEAK OF SO SEAS SIMILARLY
BENIGN AT JUST 2 FT OR LESS. LATE THURSDAY NIGHT INTO FRIDAY A FEW
KNOTS OF WIND MAY BE ADDED AS A COLD FRONT APPROACHES FROM THE NW.
NO APPRECIABLE INCREASE IN SEAS IS EXPECTED SAVE FOR A POSSIBLE
APPEARANCE OF 3 FT SEAS OUT ALONG FRYING PAN SHOALS.
LONG TERM /SATURDAY THROUGH SUNDAY/...
AS OF 3 AM WEDNESDAY...COLD FRONT TO LAZILY MOVE SOUTH ACROSS THE
ZONES ON SATURDAY. WIND SPEEDS WILL REMAIN VERY SLACK THROUGH FROPA
SO AS WIND DIRECTION TURNS FROM OFFSHORE TO ONSHORE SEAS WILL LIKELY
STAY AT THE 2 FT MARK OR LOWER. HIGH PRESSURE BUILDING IN FROM THE
NORTH AND EAST ON SUNDAY WILL ADD 5 KT OF WIND FOR A HIGHER CATEGORY
FORECAST. 3 FT SEAS SHOULD THUS RETURN TO MOST ZONES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...COLBY
SHORT TERM...BACON
LONG TERM...BACON
AVIATION...DAVE/8
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
417 PM EDT WED AUG 20 2014
.SYNOPSIS...
A FRONTAL ZONE WILL SETTLE INTO THE OHIO VALLEY THIS EVENING.
THIS FRONT WILL GRADUALLY LIFT NORTHEAST INTO THE GREAT LAKES
THROUGH THE WEEKEND. DISTURBANCES WILL INTERACT WITH A MOIST
AIRMASS TO PRODUCE SHOWERS AND THUNDERSTORMS AT TIMES THROUGH THE
PERIOD.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
CONVECTION THAT IS AFFECTING THE TRI-STATE REGION ATTM WASNT
HANDLED WELL BY THE MODELS. THE HRRR HAS TRIED TO DISSIPATE ALL
AFTERNOON. KEPT THE CONVECTION TOGETHER AND PUSHED IT THRU THE
OHIO RIVER COUNTIES LATE THIS AFTERNOON.
FIGURING OUT POPS FOR THE REST OF THE NIGHT IS TOUGH....SINCE THE
MODEL GUIDANCE DIDNT COVER THIS CURRENT CONVECTION WELL. THAT
MAKES IT HARD TO FIGURE OUT WHEN TO TRANSITION FROM THE RADAR TO
MODEL. DEVELOPED SOME PCPN IN THE TRI- STATE REGION BETWEEN
00-06Z ALONG A WEAK FRONT. THIS IS SIMILAR TO THE CMC/NAM
SOLUTION. THEN LET IT DISSIPATE AS FOCUS SHIFTS TO ENERGY TO OUR
NW.
LOWS TONIGHT WILL BE WARM AND MUGGY. TEMPERATURES WILL ONLY DROP INTO
THE UPPER 60S TO LOWER 70S.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
THERE IS A LARGE VARIATION IN MODEL SOLUTIONS FOR THURSDAY. PREFER
A NAM/CMC REGIONAL/HIRES-WRF SOLUTION WHICH DROPS H5 ENERGY INTO
THE REGION EARLY THURSDAY MORNING IN THE NW FLOW. THEY PUSH THE
BEST PCPN CHANCE ACROSS THE REGION DURING THE MORNING...AND EXIT
IT OUT OF THE EAST DURING THE AFTN.
THURSDAY NIGHT BETTER FORCING SHIFTS TO NRN OHIO AS CONVERGENCE
ALONG A LIFTING WARM FRONT MOVES ALSO. PUT HIGH CHANCE POPS IN THE
NORTHERN COUNTIES WITH DECREASING POPS DOWN TO THE SW.
ON FRIDAY...ADDITIONAL H5 ENERGY TOPS THE RIDGE AND DROPS SE
ACROSS THE REGION. THIS WILL HELP DEVELOP DAYTIME CONVECTION...BUT
CENTRAL OHIO WILL HAVE THE BEST CHANCE AT SEEING CONVECTION AS IT
IS CLOSER TO THE WARM FRONT.
CONVECTION TOMORROW WILL COMPLICATE THE HIGH TEMPERATURE FORECAST.
ONLY WENT LOWER 80S IN THE NW COUNTIES SINCE THE CONVECTION SHOULD
LIMIT HEATING THERE. SOUTHERN COUNTIES SHOULD BE ABLE TO MAKE THE
MID TO UPPER 80S. AFTER DROPPING DOWN TO ONLY AROUND 70 THURSDAY
NIGHT...FRIDAY IS LOOKING LIKE A HOT AND HUMID DAY. OHIO RIVER
COUNTIES SHOULD SEE TEMPERATURES PUSH INTO THE LOWER 90S WITH
DEWPOINTS IN THE LOWER 70S. THIS WILL PUSH HEAT INDICES OVER 100.
WILL CONTINUE TO HIGHLIGHT THE THREAT IN THE HWO.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AT 12Z ON SATURDAY...THE 20.12Z ECMWF AND GFS ARE VERY GOOD
AGREEMENT ON THE LARGE SCALE PATTERN WITH AN AMPLIFIED FLOW PATTERN
OVER THE LOWER 48. A DEEP CLOSED LOW SHOULD BE OVER ID/MT WITH A
STRONG SUBTROPICAL RIDGE EXTENDING NORTHEAST FROM A 593DM HIGH OVER
ALABAMA. ANOMALOUS MOISTURE WILL STILL BE IN PLACE WITH PWAT FROM
1.5 TO 2.0 STANDARD DEVIATIONS ABOVE CLIMO. THROUGH THE WEEKEND THE
STRONG CLOSED LOW WILL SWING NORTHEAST INTO THE NRN HIGH PLAINS AND
EVENTUALLY INTO SASK...WHILE THE RIDGE EXPANDS NORTHEASTWARD INTO
TN/ARK. DESPITE WEAK FORCING...CONTINUED NORTHERLY/NORTHWESTERLY
FLOW AROUND THE RIDGE...THE PRESENCE OF A WEAK SURFACE TROUGH...AND
ANOMALOUS MOISTURE SHOULD CONTINUE TO ALLOW FOR STRONG DAYTIME
INSTBY BOTH SAT AND SUN. THE POTENTIAL FOR ONE MORE CLUSTERS OF SSE
PROPAGATING STORM CLUSTERS WILL CONTINUE THROUGH THE WEEKEND. GIVEN
THE MAGNITUDE OF INSTBY...EVEN WITH WEAKENING FLOW WITH TIME...THERE
COULD BE STRONG/SEVERE STORM THREAT ON EITHER OF THESE DAYS IF A
ORGANIZED COLD POOL COULD FORM. GETTING INTO MONDAY-TUESDAY...THE
RIDGE CONTINUES TO BUILD WITH HEAT/HUMIDITY. FLOW BECOMES VERY LIGHT
THROUGH THE BULK OF THE TROPOSPHERE AND IT BECOMES QUESTIONABLE IF
COVERAGE OF DAYTIME/EVE STORMS WARRANTS MENTION. RIGHT NOW HAVE RUN
15-25% RAIN CHANCES BOTH OF THESE DAYS...AND THAT MAY BE TOO HIGH.
INTO WEDNESDAY...SOME HINTS OF HEIGHT FALLS WHICH MAY ALLOW A LITTLE
STRONGER FLOW OR A WEAK SHORTWAVE TROUGH TO CROSS THE GREAT LAKES.
SO A BETTER STORM THREAT THEN...HOWEVER AT THIS TIME RANGE THIS IS A
VERY LOW CONFIDENCE FORECAST GIVEN CONDITIONAL NATURE OF THE RIDGE
BUCKLING.
SO ALL IN ALL...HAVE TENDED TO FOCUS RAIN CHANCES NEAR PEAK HEATING
INTO THE EVENING AND ALLOW FOR SOME DRY NIGHTS/EARLY MORNINGS. FLY
IN OINTMENT WILL BE ANY FORWARD PROPAGATING MCS THAT SURVIVES
THROUGH THE NIGHT...ORIGINATING TO OUR NORTHWEST AND FALLING DOWN
NNWLY FLOW EITHER SATURDAY MORNING OR SUNDAY MORNING. LOW CONFIDENCE
STORM CHANCE...BUT HIGH CONFIDENCE WARM/HUMID PATTERN IS THE STORY
FOR THE SAT-WED TIMEFRAME.
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
CONVECTION TO THE WEST OF THE AREA IS EXPECTED TO WEAKEN BEFORE
REACHING THE CINCINNATI TERMINALS. THERE WILL BE A LOT OF LEFT
OVER CLOUDS ALTHOUGH THEY ARE EXPECTED TO BE VFR. ELSEWHERE
SCATTERED CUMULUS WILL DISSIPATE WITH LOSS OF HEATING.
QUITE A BIT OF UNCERTAINTY REGARDING POTENTIAL FOR THUNDERSTORMS
DURING THE LATTER HALF OF THE FORECAST PERIOD. APPEARS THAT STORMS
COULD START TO DEVELOP AFTER 06Z. ONCE STORMS DO DEVELOP THERE
COULD BE REPEATED ACTIVITY OVER THE SAME AREA BEFORE A LULL OCCURS
LATE IN THE FORECAST PERIOD.
OUTLOOK...THUNDERSTORMS POSSIBLE THURSDAY AFTERNOON THROUGH
SUNDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...SITES/SNYDER
NEAR TERM...SITES
SHORT TERM...SITES
LONG TERM...BINAU
AVIATION...
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
205 PM EDT WED AUG 20 2014
.SYNOPSIS...
A BROAD UPPER LEVEL RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE
MISSISSIPPI RIVER VALLEY OVER THE NEXT FEW DAYS AND LINGER FOR THE
REST OF THE WORK WEEK...RESULTING IN ABOVE NORMAL TEMPERATURES. A
WEAK COLD FRONT WILL THEN PUSH INTO THE AREA FROM NORTHEAST SATURDAY
AND BRING SOME MINOR RELIEF FROM THE HEAT.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 155 PM...PERSISTENT SMALL STRONG TO OCCASIONALLY SEVERE
CONVECTIVE CLUSTER CONTINUES TO DROP SOUTHEAST ACROSS THE NC
FOOTHILLS. SCT CONVECTION IS FINALLY BEGINNING TO UNZIP A BIT ALONG
THE OUTFLOW BOUNDARY ALONG THE I-40 CORRIDOR INTO THE NW PIEDMONT.
OTHERWISE...THE LATEST SPC MESOANALYSIS DEPICTS A MINIMUM IN CAPE
ACROSS THE AREA...WITH CAPE EXCEEDING 3000 J/KG JUST TO OUR EAST...
AND MORE THAN 4000 J/KG ACROSS EAST TENN INTO NRN/CTRL GEORGIA. THIS
IS WHERE THE BEST CONVECTIVE COVERAGE IS ONGOING. WE HAVE DELAYED
THE BEST POPS UNTIL LATE IN THE AFTERNOON AND TOWARD EARLY
EVENING...WHEN INSTABILITY SHOULD BE GREATEST AND CHANCES WILL ALSO
INCREASE FOR UPSTREAM ACTIVITY...POSSIBLY ORGANIZING UPSCALE...TO
MOVE INTO THE FORECAST AREA. BRIEF LARGE HAIL AND DAMAGING WINDS
WILL REMAIN POSSIBLE...WITH DOWNBURST POTENTIAL ENHANCED WITH ANY
ORGANIZED CLUSTERS.
AS OF 11 AM...A SMALL CLUSTER OF DEEP CONVECTION IS APPROACHING THE
NORTHERN NC MTNS ATTM...THUS POPS HAVE BEEN INCREASED TO LIKELY IN
THE AREAS NORTH OF I-26 ALONG THE TENN BORDER. THE PREVIOUS REMNANT
CONVECTIVE AREA DISSIPATED AS IT MOVED EAST OF THE MTNS. HOWEVER...
THE ATMOSPHERE IS HEATING STRONGLY DOWNSTREAM OF THE HIGH TERRAIN.
REGIONAL RAOBS PAINTED A RATHER STARK CONTRAST FROM THIS TIME
YESTERDAY...ESP AT KFFC...WHERE A LAYER OF NEAR-DRY ADIABATIC LAPSE
RATES WERE OBSERVED BETWEEN H8 AND H6. AS A RESULT...THE AIRMASS IS
RAPIDLY DESTABILIZING EAST OF THE MTNS...WITH CAPE ALREADY EXCEEDING
1500 J/KG ACROSS THE FOOTHILLS AS OF 14Z. IT APPEARS LIKELY THAT
CAPE WILL INCREASE TO THE NEIGHBORHOOD OF 3000 J/KG THIS AFTERNOON.
CONVECTION IS ALREADY SHOWING SIGNS OF FANNING OUT ALONG THE OUTFLOW
BOUNDARY ACROSS NORTHEAST TENN...AND WITH CAPE INCREASING STRONGLY
DOWNSTREAM...IT SEEMS ENTIRELY PLAUSIBLE THAT SCATTERED CONVECTION
WILL CONTINUE TO DEVELOP ALONG THE BOUNDARY AS IT PUSHES EAST OF THE
MTNS BY EARLY AFTERNOON (THE LATEST HRRR IS SUGGESTING A SIMILAR
SCENARIO). AS SUCH...POPS HAVE BEEN INCREASED BY 10-20 PERCENT IN
MOST AREAS THIS AFTERNOON...WITH 40 POPS NOW BEING FEATURED AS FAR
SOUTHEAST AS THE I-85 CORRIDOR.
POPS HAVE ALSO BEE INCREASED FOR THIS EVENING. AN AXIS OF CAPE >
3000 IS ALREADY BEING ANALYZED ACROSS MIDDLE TENN INTO SE KENTUCKY.
SHORT TERM GUIDANCE ALSO DEPICTS A CORRIDOR OF 20-30KTS OF LOW LEVEL
SHEAR THIS AFTERNOON FROM EASTERN KENTUCKY INTO SOUTHWEST NC. A
CONSENSUS OF MESOSCALE MODEL GUIDANCE WOULD SUGGEST ORGANIZED MCS
DEVELOPMENT IN THESE AREAS BY LATE AFTERNOON...POSSIBLY DROPPING
SOUTHEAST INTO THE FORECAST AREA THIS EVENING. HOW THIS PLAYS OUT
FOR OUR AREA MAY DEPEND LARGELY UPON THIS AFTERNOON/S CONVECTIVE
EVOLUTION...BUT IT SEEMS THE AREA MOST LIKELY TO BE AFFECTED WOULD
BE ACROSS (ROUGHLY) THE NORTHWEST HALF OF THE FORECAST AREA...WHERE
POPS WERE INCREASED TO 40-50 PERCENT THIS EVENING. LOWERING FREEZING
LEVELS AND LARGE DCAPE SHOULD SUPPORT A RISK OF ISOLATED LARGE HAIL
AS WELL AS DAMAGING WINDS...WITH THE POTENTIAL FOR AN ENHANCED
DOWNBURST RISK WITH ANY UPSCALE ORGANIZATION.
1030 UTC UPDATE...POPS HAVE BEEN ADJUSTED PER RADAR TRENDS...WITH A
DECREASE EARLY ON. SKY COVER WAS UPDATED FROM INFRARED SATELLITE
IMAGERY...ALSO RESULTING IN A DECREASE. AREAS OF FOG WERE REDUCED
BASED ON OBSERVATIONS AND DEW POINT DEPRESSIONS.
AT 300 AM EDT TUESDAY...AN UPPER TROUGH WILL AMPLIFY ALONG THE EAST
COAST TODAY...WHILE AN UPPER RIDGE BUILDS NORTH OVER THE MS RIVER
VALLEY. SEVERAL WEAK SHORTWAVES WILL CROSS OUR AREA TODAY AND
TONIGHT IN NW FLOW ALOFT....WHILE A COLD FRONT ADVANCES SLOWLY FORM
THE NE. IT IS UNCLEAR WHETHER THE FRONT WILL MAKE IT VERY FAR INTO
OUR AREA...BUT ITS GENERAL PROXIMITY MAY FOCUS CONVECTION ACROSS OUR
NORTHERN TIER OF COUNTIES. EVEN IF THE FRONT REMAINS OFF TO THE
NORTHEAST...OUR AREA WILL BE IN A MOIST UNSTABLE AIR MASS...AND
PASSING SHORTWAVES WILL PROVIDE SUPPORT FOR CONVECTION. MOISTURE
WILL BE SOMEWHAT LIMITED...AND STEERING FLOW GREAT ENOUGH TO KEEP
CELLS MOVING...LIMITING THE POTENTIAL FOR HEAVY RAINFALL. ROBUST
CAPE WILL BE PRESENT...AND DRY AIR WILL BE AVAILABLE FOR EVAPORATIVE
COOLING...PROVIDING SUPPORT FOR WIND GUSTS AND HAIL. HIGH
TEMPERATURES WILL BE SLIGHTLY ABOVE NORMAL.
SOME ELEVATED INSTABILITY WILL LINGER THROUGH TONIGHT...AND IF ANY
MCS ROUNDING THE CORNER OF THE RIDGE REACHES OUR AREA...IT MAY WELL
SURVIVE. STEERING FLOW AND A LACK OF DEEP MOISTURE WILL LIMIT HEAVY
RAINFALL POTENTIAL. MINIMUM TEMPERATURES WILL RUN ABOVE NORMAL IN A
MOIST AIRMASS.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM WEDNESDAY...A LARGE UPPER RIDGE WILL PERSIST ACRS THE
LWR-MID MS VALLEY...EXTENDING EAST ACRS THE SOUTHEAST STATES THRU
THE SHORT TERM. THE LATEST GUIDANCE SHOWS THAT A RING OF FIRE
PATTERN WILL SET UP...WITH A SERIES OF SHORTWAVES AND ASSOCIATED
CLUSTERS OF CONVECTION WILL RIDE OVER TOP OF THE RIDGE...FROM THE
UPR MIDWEST/SRN GREAT LAKES...TO THE MID ATLANTIC. IT LOOKS LIKE
MOST OF THE ASSOCIATED ACTIVITY WILL STAY NORTH OF THE CWFA.
HOWEVER...THE NRN ZONES (GENERALLY I-40 CORRIDOR AND NORTH)...MAY
GET BRUSHED BY A POSSIBLE MCS AT SOME POINT. NOT MUCH CHANGE WAS
MADE TO THE POPS. STILL EXPECT AT LEAST A HANDFUL OF
DIURNALLY-DRIVEN CONVECTION...AS STEEP MID LVL LAPSE RATES REMAIN
ATOP THE REGION. MODELS ARE TRENDING WARMER FOR THURSDAY AND
FRIDAY...SO I BUMPED UP TEMPS ABOUT A CATEGORY...EVEN MORE IN THE NW
NC PIEDMONT...WHERE WE PREVIOUSLY THOUGHT A BACKDOOR COLD FRONT
WOULD PUSH IN BY FRIDAY. THIS RESULTS IN ABOVE NORMAL TEMPS...WITH
UPR 80S IN THE MTN VALLEYS AND MID-UPR 90S ACRS THE PIEDMONT.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 1230 PM WEDNESDAY...MEDIUM RANGE MODELS ARE IN DECENT ENUF
AGREEMENT WITH RESPECT TO THE MEAN PATTERN FOR THE FIRST HALF OF THE
EXTENDED PERIOD FEATURING LLVL RIDGING POKING SSW INTO THE CWFA. THE
COMBINATION OF THE LLVL EASTERLY FLOW AND THE HIGHLY AMPLIFIED NLY
FLOW SHOULD RESULT IN ENUF FORCING FOR AT LEAST SCATTERED
SHOWERS...AND MAX TEMPERATURES A FEW DEG F BELOW PERSISTENCE AND A
CATEGORY OR TWO BELOW CLIMO SUNDAY AND MONDAY.
WITH LLVL RIDGING LIKELY TO LINGER THRU TUESDAY...THERE REMAINS ABOVE
NORMAL CONFIDENCE THAT MAXIMUM TEMPERATURES WILL CONTINUE TO AVERAGE
BELOW CLIMO. IT REMAINS TO BE SEEN ON JUST HOW MUCH FORCING IS
AVAILABLE TO TRIGGER SHOWER ACTIVITY...SO JUST A TOKEN SLIGHT AND/OR
SMALL POP WILL REMAIN.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...CONVECTION AT THIS MOMENT IS PRIMARILY
LIMITED TO A SMALL/PERSISTENT CLUSTER OF STRONG TO SEVERE CONVECTION
OVER THE SOUTHERN NC FOOTHILLS. THIS WILL NOT THREATEN ANY OF THE
TAF SITES IN THE NEAR TERM. HOWEVER...THERE ARE SIGNS THAT SCATTERED
CONVECTION MAY BE IN THE PROCESS OF /FANNING OUT/ ALONG THE OUTFLOW
BOUNDARY LAID DOWN BY THIS CONVECTION. THEREFORE...TEMPOS FOR TSRA
WILL BE CONTINUED AT KCLT...AND INTRODUCED AT KGSP THROUGH THE
AFTERNOON. THE TEMPO HAS BEEN SCALED BACK TO SHRA AT KHKY AND
COMPLETELY REMOVED AT KAVL...SINCE THE OUTFLOW HAS NOW ESSENTIALLY
PASSED THEM. HOWEVER...ADDITIONAL DEVELOPMENT WILL BE POSSIBLE NEAR
THESE SITES AND ALL OTHER TAF SITES THIS AFTERNOON. CONVECTION MAY
ALSO ORGANIZE ACROSS THE TENN VALLEY THIS AFTERNOON AND PUSH
SOUTHEAST ACROSS THE SOUTHERN APPALACHIANS AND SURROUNDING AREAS
INTO THE EVENING. THEREFORE...A VCTS/VCSH WILL BE CARRIED AT ALL
TERMINALS THROUGH ABOUT 03Z.
EVEN OUR MOST RELIABLE GUIDANCE IS ONCE AGAIN HITTING THE FOG HARD
LATE TONIGHT...AS IT HAS BEEN DOING THE PASTS SEVERAL MORNINGS...
WITH VERY POOR VERIFICATION RESULTS. THEREFORE...WE HAVE IMPROVED
THE VISBY FORECAST CONSIDERABLY OVER WHAT GUIDANCE IS ADVERTISING...
BUT THIS IS STILL RESULTING IN A 3SM FORECAST AT KAVL. OTHERWISE...
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD OUTSIDE OF SHRA/
TSRA.
OUTLOOK...SCT AFTERNOON CONVECTION AND PATCHY EARLY MORNING FOG WILL
REMAIN IN THE FORECAST THROUGH THE WEEK. THERE WILL ALSO BE AN
OUTSIDE CHANCE FOR REMNANT ORGANIZED CONVECTION APPROACHING THE
AREA FROM THE NW DURING THE LATE NIGHT/EARLY MORNING HOURS.
CONFIDENCE TABLE...
18-24Z 00-06Z 06-12Z 12-18Z
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAVL HIGH 100% HIGH 95% HIGH 95% HIGH 95%
KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 100% HIGH 100% HIGH 95% HIGH 91%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...ARK
NEAR TERM...JAT/JDL
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...JDL
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1254 PM CDT WED AUG 20 2014
.UPDATE...
ISSUED AT 1008 AM CDT WED AUG 20 2014
CURRENT CONVECTION IN EASTERN NEBRASKA CONTINUES TO FILTER
NORTHEASTWARD INTO PARTS OF NORTHWEST IA...EXTREME NORTHEAST NEB
AND FAR SOUTHEAST SD THIS MORNING. THIS ACTIVITY IS ASSOCIATED
WITH A 700MB WAVE...MARKED BY DECENT MID LEVEL FRONTOGENESIS AND
STRONG MID LEVEL SPEED CONVERGENCE IN THAT AREA. SIGNALS BASED OFF
OF THE 12Z NAM CONTINUE TO POINT AT A GRADUAL WEAKENING OF THESE
FEATURES INTO MIDDAY...ALBEIT THERE ARE SOME INDICATIONS THAT THE
MID LEVEL CONVERGENCE MAY MAKE IT ALL THE WAY TOWARD THE IA GREAT
LAKES AREA AND STORM LAKE EARLY THIS AFTERNOON. SO THAT WILL NEED
MONITORED TO SEE IF WE NEED TO INCREASE AFTERNOON POPS IN THAT
AREA.
THIS CONVECTION HAS REALLY FOULED UP THE LOW LEVEL AND SURFACE
BOUNDARIES THIS MORNING. AT THIS TIME...IT APPEARS THAT THE
CURRENT POSITION OF THE MAIN WARM FRONT IS STILL AROUND THE OMAHA
AREA PUSHED SOUTHWARD BY THE RAINFALL. THE VARIOUS SHORTER RANGE
MODELS ARE ALL OVER THE MAP IN HOW THEY LIFT THE FRONT...OR FRONTS...
NORTHWARD THIS AFTERNOON AND EVENING. FURTHERMORE...THE NEW 12Z
NAM HAS THE MAIN SHORT WAVE LIFTING OUT MUCH FURTHER TO THE
NORTHWEST AND NORTH OF OUR FORECAST AREA TONIGHT...WITH A LOBE OF
UPPER QG FORCING ARCING SOUTHWARD INTO OUR AREA THIS EVENING FROM
THE PARENT SHORT WAVE TO OUR NORTH. SO FOR TONIGHT...THE ACTUAL WAVE
MAY NOT BE MUCH OF A PLAYER FOR OUR FORECAST AREA. IN ADDITION...THE
SURFACE WIND SHIFT TO THE WEST DOES NOT TAKE PLACE UNTIL TOMORROW.
SO ANY TORNADIC ACTIVITY WILL LIKELY HAVE TO BE CONFINED TO NEAR
THE NORTHWARD LIFTING WARM FRONT WHICH IS DIFFICULT TO PROG.
FOLLOWING THE 4KM NAM AND HRRR AS GUIDES SINCE THEY ARE VERY CLOSE...
IT APPEARS THAT ONE WARM FRONTAL BOUNDARY SCOOTS NORTHWARD WITH
THE WARM AIR ADVECTION TODAY...EVENTUALLY SETTING UP AND STALLING
GENERALLY FROM CENTRAL ND...TO NORTHEAST SD...AND DOWN TO JUST
NORTH OF MARSHALL MN THIS EVENING. BUT THERE IS A SECOND BOUNDARY
AS WAS SHOWN YESTERDAY GENERALLY EXTENDING FROM LOW PRESSURE IN
WEST CENTRAL SD...TO NEAR CHAMBERLAIN AND SIOUX CITY FROM 21Z TO
03Z TODAY...THEN WASHES OUT LIKELY DUE TO THE SHORT WAVE PASSAGE
TO OUR NORTHWEST. AFTER ALL OF THIS MORNING AND MIDDAY CONVECTION
IN OUR SOUTHERN ZONES...WORRIED THAT THE SOUTHERN PART OF THIS
SECOND WARM FRONT IN OUR SOUTHERN ZONES COULD BE CAPPED OFF INTO
THE EARLY EVENING HOURS. THIS WOULD INCLUDE THE SIOUX CITY...
YANKTON AND STORM LAKE AREAS. BUT FURTHER WEST TOWARD CENTRAL SD
WHERE STRONGER HEATING SHOULD OCCUR...THAT AREA COULD HAVE ENOUGH
LOW LEVEL CURVATURE TO SPAWN ISOLATED TORNADOES THIS EVENING...
AROUND THE CHAMBERLAIN AND MITCHELL AREAS...POSSIBLY EXTENDING
NORTHWARD THEN THROUGH THE EVENING CLOSER TO HIGHWAY 14 IN OUR
SOUTH DAKOTA ZONES. THE AFOREMENTIONED SURFACE LOW TO THE WEST
SHOULD ALSO AID IN LOW LEVEL CURVATURE IN OUR FAR WESTERN ZONES.
SO THIS APPEARS TO BE THE AREA RIGHT NOW FOR THE BEST CHANCE FOR
TORNADIC ACTIVITY THIS EVENING...AT LEAST WITH THE CURRENT
ANALYSIS. A BROADER RISK OF SEVERE WEATHER IS CERTAINLY WARRANTED
THROUGH THE FORECAST AREA INTO THE MIDDLE OF THE NIGHT ALONG THE
UPPER QG FORCING LOBE WHICH WAS MENTIONED ABOVE. WILL CONTINUE TO
MONITOR FOR THE LATEST TRENDS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT WED AUG 20 2014
SHOWERS AND THUNDERSTORMS EXPANDING THIS MORNING ALONG AND JUST
SOUTH OF THE MISSOURI RIVER IN AN AREA OF INCREASING ISENTROPIC LIFT
ON THE EDGE OF THE LOW LEVEL JET. THESE STORMS SHOULD GENERALLY
REMAIN SUB SEVERE WITH BRIEF HEAVY RAIN...ALTHOUGH A FEW MARGINALLY
SEVERE HAIL REPORTS ARE POSSIBLE. NOT REALLY A STRAIGHT FORWARD
FORECAST AS WE GO THROUGH THE THE DAY TODAY INTO TONIGHT REGARDING
CONVECTIVE EVOLUTION. THOUGHT IS THE ELEVATED CONVECTION THIS
MORNING WILL GENERALLY BEGIN TO WEAKEN AND DISSIPATE BY MID MORNING
AS THE AREA OF ISENTROPIC LIFT MOVES NORTH INTO DRIER AIR AND WE
HAVE THE DIURNAL WEAKENING OF THE LOW LEVEL JET. THIS IS SUPPORTED
BY A MAJORITY OF THE HI RES GUIDANCE. STILL SHOULD BE QUITE A BIT OF
MID LEVEL CLOUDINESS THAT STICKS AROUND THROUGH THE DAY...AND
POSSIBLY AN ISOLATED ELEVATED SHOWER OR STORM. BUT GENERALLY
THINKING THE DAY ENDS UP MAINLY DRY...UNTIL WE SEE A REGENERATION
THIS EVENING INTO THE OVERNIGHT...WHICH WILL BE DISCUSSED BELOW.
HIGHS TODAY TRICKY AS WELL GIVEN CLOUD COVER UNCERTAINTY. WILL
CONTINUE TO GO MIDDLE GROUND FOR HIGHS...WITH THE CLOUD COVER...HIGH
BOUNDARY LAYER MOISTURE...AND SOUTHEASTERLY WINDS LIMITING MIXING.
STILL SHOULD SEE MID TO UPPER 80S...WHICH COMBINED WITH THE HIGH
DEWPOINTS WILL RESULT IN HEAT INDICES FROM THE UPPER 80S TO MID
90S...HIGHEST ALONG THE MISSOURI RIVER.
MAIN FOCUS OF THIS FORECAST IS ON SEVERE WEATHER CHANCES THIS
AFTERNOON AND TONIGHT. THROUGH THE DAY A WARM FRONT WILL WORK ITS
WAY NORTH...SETTING UP SOMEWHERE ACROSS THE CWA BY THIS EVENING.
THIS WILL ENHANCE LOW LEVEL SHEAR...WITH 0 TO 1 KM SHEAR EXPECTED TO
BE 15 TO 20 KTS. GOOD TURNING OF THE WINDS WITH HEIGHT WILL ALSO
RESULT IN DEEP LAYER SHEAR OF 40 OR MORE KTS...SUFFICIENT FOR
SUPERCELLS. MLCAPE SHOULD BE PLENTIFUL AS WELL WITH MOST LOW LEVELS
AND STEEP LAPSE RATES ALOFT RESULTING IN VALUES OF 2000 TO 3000
J/KG. AM CONCERNED ABOUT LOW LEVEL LAPSE RATES AND STABILITY THOUGH.
MODEL SOUNDINGS SHOW A PRETTY GOOD CAP IN PLACE FOR MUCH OF THE DAY.
LOW LEVEL FORCING DOES NOT SEEM STRONG ENOUGH TO OVERCOME THIS FOR
MOST OF THE DAY...WHICH SHOULD KEEP SURFACE BASED CONVECTION AT BAY.
THE UPPER WAVE WILL PASS BY TO OUR NORTH THIS AFTERNOON AND
EVENING...BUT SHOULD PASS TOO FAR NORTH TO AID TOO MUCH IN
CONVECTIVE DEVELOPMENT...AS 700 AND 500 MB HEIGHT FALLS ARE MINIMAL
TO NON EXISTENT. THUS CONVECTIVE DEVELOPMENT WILL RELY MAINLY ON
FORCING FROM THE WEST TO EAST MOVING COLD FRONT AND THE INCREASING
LOW LEVEL JET TOWARDS 0Z. PREFER TIMING AND PLACEMENT CLOSE TO THE
06Z 4KM NAM...AND 4KM NMMB. THIS WOULD GIVEN CONVECTIVE INITIATION
ACROSS CENTRAL SOUTH DAKOTA...WITH STORMS MOVING TOWARDS CHAMBERLAIN
AND HURON BETWEEN 6PM AND 9PM. GIVEN THE AMPLE CAPE...STORMS SHOULD
BE ABLE TO THEN PROGRESS ACROSS MUCH OF THE CWA...APPROACHING
INTERSTATE 29 AFTER 10 PM AND THE EASTERN CWA AFTER MIDNIGHT. GIVEN
THE GOOD MODEL AGREEMENT WENT WITH LIKELY POPS MOST AREAS...STAYED
SHY OF GOING CATEGORICAL GIVEN THAT THERE IS STILL A CHANCE THE
STORMS PEEL OFF TO THE NORTH CLOSER TO THE BETTER UPPER SUPPORT.
IN GENERAL THE SPC SLIGHT RISK AND PROBABILITIES SEEM GOOD. GIVEN
THE STEEP LAPSE RATES ALOFT AND GOOD SHEAR...LARGE HAIL OF TENNIS
BALL SIZE WILL INITIALLY BE A THREAT. THIS VERY LARGE HAIL THREAT
SHOULD MAINLY BE CLOSER TO WHERE STORMS INITIATE...LIKELY THE
VICINITY OF THE JAMES RIVER OR WEST. AS STORMS MOVE EAST...SOME
LARGE HAIL WILL STILL BE POSSIBLE...BUT THE STRONG WIND THREAT
SHOULD ALSO INCREASE. TORNADO THREAT IS UNCERTAIN GIVEN THE
UNCERTAINTY ON WHETHER STORMS BECOME NEAR SURFACE BASED. BUT GIVEN
THE SHEAR MENTIONED ABOVE...CAN NOT RULE OUT A TORNADO OR
TWO...GREATEST THREAT AGAIN APPEARS TO BE WEST OF INTERSTATE
29...PROBABLY EVEN ALONG OR JUST WEST OF THE JAMES RIVER. HEAVY RAIN
WILL ALSO BE LIKELY IN ANY STORMS...WITH PWATS UP TO 3 STANDARD
DEVIATIONS ABOVE NORMAL. STORMS SHOULD BE MOVING ENOUGH TO PREVENT A
BIG FLASH FLOOD RISK...ALTHOUGH LOCALIZED FLOODING WOULD BE POSSIBLE
IN THE HEAVIER STORMS.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 341 AM CDT WED AUG 20 2014
THURSDAY LOOKS WARM...DRY AND HUMID AS UPPER LEVEL RIDGING BUILDS
ACROSS THE REGION. MAIN CONCERN ON THURSDAY WILL BE HEAT INDICES.
WHILE NOT QUITE TO ADVISORY LEVELS COULD SEE SOME LOWER TO MIDDLE
90S FOR HEAT INDICES WHICH WILL FEEL PRETTY HOT GIVEN THE EXPECTED 5
TO 10 MPH WIND.
THURSDAY NIGHT INTO FRIDAY WILL SEE A TROUGH OF LOW PRESSURE SWING
ONTO THE PLAINS WHICH WILL BRING A GRADUALLY INCREASING THREAT FOR
THUNDERSTORMS. JUST A SLIGHT CHANCE THURSDAY NIGHT THEN BECOMING
MUCH MORE LIKELY LATE FRIDAY AFTERNOON AND FRIDAY NIGHT. ISOLATED
SEVERE THUNDERSTORMS AS WELL AS HEAVY RAIN WILL BE A THREAT. FRIDAY
LIKELY TO BE PRETTY WARM AND HUMID...ESPECIALLY THE SOUTHEAST HALF
OF THE CWA. HEAT INDICES LIKELY 90 TO 95 IN THESE AREAS.
IN THE OUTER PERIODS (SATURDAY THROUGH TUESDAY)...A FAIRLY STRONG
TROUGH OF LOW PRESSURE IS FORECAST TO MOVE ACROSS THE NORTHERN
PLAINS SATURDAY NIGHT INTO SUNDAY NIGHT. THE TIMING AND STRENGTH ARE
FAIRLY CONSISTENT IN THE LATEST MODELS SO WILL CONTINUE WITH MID
RANGE POPS DURING THIS TIME. ALSO LOOKS LIKE A DECENT CHANCE FOR
SOME SPOTTY HEAVY RAINFALL AS THE UPPER LEVEL FLOW LOOKS TO POSSIBLY
BECOME PARALLEL TO THE LOW LEVEL BOUNDARY...WHICH COULD SUPPORT SOME
TRAINING OF THUNDERSTORMS. A LITTLE TOO FAR OUT TO REALLY NAIL THIS
DOWN BUT SOMETHING TO WATCH FOR. AS THE WAVE PASSES COOLER AIR WILL
SETTLE INTO THE AREA AND WITH CONTINUED TROUGHING TO THE WEST THE
THREAT FOR SHOWERS AND THUNDERSTORMS...AS WELL AS ADDITIONAL CLOUD
COVER...WILL ALSO CONTINUE. TEMPERATURE GUIDANCE IN THIS TIME FRAME
IS ALREADY BELOW NORMAL AND SEE NO REAL REASON TO STRAY TOO FAR FROM
THAT. STATISTICALLY A GOOD SIGNAL WITH THE GFS MEX GUIDANCE BELOW
CLIMATOLOGICAL NORMALS AND THE ENSEMBLE MEAN OUTPUT COOLER YET WHICH
IS USUALLY A BIG HINT TO STAY BELOW THE COLDER MEN TEMPERATURES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1253 PM CDT WED AUG 20 2014
FOR STARTERS...VERY COMPLEX PATTERN IS NOT LENDING A LOT OF
CONFIDENCE TO THE 18Z TAFS. THE PRIMARY WARM FRONT IS STILL WELL
SOUTH OF OUR FORECAST AREA AT THIS TIME...WITH AN ELEVATED WARM
FRONT CONTINUING TO LIFT NORTHWARD. CONVECTION IS CURRENTLY FIRING
ALONG THE ELEVATED WARM FRONT...COUPLED WITH A SHORT WAVE NEAR
700MB ALONG OUR MO RIVER VALLEY ZONES. THOUGHTS ARE THAT THIS
ACTIVITY WILL LIFT NORTHEASTWARD THROUGH THE AFTERNOON. THEREFORE
PUT IN A CHANCE FOR THUNDERSTORMS FOR THE SIOUX FALLS TAF SITE VERY
LATE THIS AFTERNOON AND VERY EARLY IN THE EVENING...BASED ON THE
TIMING OF THE ELEVATED WARM FRONTAL PASSAGE. DYNAMICS SHOULD BE
COMING TO A CLOSE AROUND SIOUX CITY BY MID AFTERNOON AS THE
ELEVATED WARM FRONT LIFTS NORTHWARD. THEREFORE ENDED THE PRECIP
THREAT FOR SIOUX CITY BY THAT TIME. AS THE PRIMARY UPPER SHORT
WAVE LIFTS THROUGH NORTHERN SD AND NORTH DAKOTA THIS EVENING...
CONTINUED TO PLACE THUNDERSTORM CHANCES FOR THE KHON TAF SITE
DURING THE EVENING HOURS. BUT FURTHER SOUTH...THERE COULD BE A
BREAK IN THE KFSD TAF SITE AFTER EARLY EVENING UNTIL THE OVERNIGHT
HOURS. RIGHT DURING THE MIDDLE OF THE NIGHT...AS THE MAIN SHORT
WAVE LIFTS NORTH OF KFSD...THERE COULD BE A PERIOD OF SHOWERS AND
STORMS WHICH WERE MENTIONED IN THE KFSD TAF ASSOCIATED WITH THE
MAIN WAVE IN NORTHERN SD...AS CONVECTION COULD DEVELOP SOUTHWARD
INTO A STOUT LOW LEVEL JET. BUT KSUX MAY BE TOO FAR SOUTH FOR
NOCTURNAL ACTIVITY TONIGHT...OR AT LEAST LESS CONFIDENT OF
CONVECTION...SO LEFT KSUX DRY FOR TONIGHT.
LASTLY...THE LATEST HIRES NAM IS HINTING AT STRATUS DEVELOPMENT
FOR KHON AND KFSD LATE TONIGHT AND EARLY THURSDAY BEHIND THE SHORT
WAVE DEPARTURE. IF RAIN PANS OUT TONIGHT...THIS IS A DISTINCT
POSSIBILITY AS WINDS ARE LIGHT WITH RESIDUAL MOISTURE LINGERING.
FOR NOW...HEDGED MVFR CONDITIONS FOR THOSE TWO LOCATIONS FOR THIS
POSSIBILITY.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...MJ
SHORT TERM...CHENARD
LONG TERM...08
AVIATION...MJ
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
119 PM EDT WED AUG 20 2014
.SYNOPSIS...
A WEAK STATIONARY FRONT WILL REMAIN IN THE AREA THROUGH THE REST
OF THE WEEK. UPPER LEVEL DISTURBANCES TRACKING EAST AND SOUTHEAST
ACROSS THE BOUNDARY WILL BRING SCATTERED SHOWERS AND STORMS TO THE
REGION EACH DAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 955 AM EDT WEDNESDAY...
BAND OF DEEP CONVECTION CONTINUES TO PUSH SE OUT OF THE MOUNTAIN
EMPIRE REGION INTO THE BLUE RIDGE ATTM AND EXPECT THIS AXIS TO
PERSIST UNTIL PERHAPS TOPPING THE FOOTHILLS IN THE NEXT HOUR OR
SO. THIS DESPITE LACK OF INSTABILITY AHEAD OF THE SHRA/TSRA
COMPLEX AS FEED OF BETTER CAPES AND THETA-E ADVECTION OFF TO THE
WEST PROVIDING SUPPORT. THIS AHEAD OF THE MID LEVEL SHORTWAVE
TROUGH THAT IS CURRENTLY APPROACHING THE WESTERN SLOPES AND ALONG
THE RESIDUAL SURFACE FRONT THAT HAS BACKDOORED SW INTO SW VA EARLY
THIS MORNING.
ALTHOUGH EXPECTING THIS PRECIP TO FADE...COMBINATION OF EARLY
CLOUDS/SHRA OVER THE WEST AND LINGERING FOG/STRATUS IN THE EASTERN
WEDGE WILL MAKE THINGS TRICKY IN REGARDS TO POSSIBLE RENEWED
AFTERNOON CONVECTION. MOST EARLIER GUIDANCE AND CURRENT SHORT TERM
SOLUTIONS WANT TO REDEVELOP TSRA ALONG THE BLUE RIDGE BEFORE
SLIDING THIS EAST INTO EARLY EVENING AS THE TROUGH AXIS LIFTS NE.
HOWEVER THE LATEST HRRR ONLY SHOWS ISOLATED COVERAGE BLUE RIDGE
AFTER CURRENT SHRA FIZZLES WHILE THE 12Z NAM SLOWER IN HOLDING OFF
MOST NEW CONVECTION UNTIL LATE OR EARLY EVENING EAST WITH SOME
WEAK CAPPING ALOFT UNDER RESIDUAL CLOUDS IN THE WAKE OF THE
CURRENT COVERAGE. THUS HAVE ADJUSTED POPS DOWN SOME IN THE FAR
WEST AND TRIMMED LIKELYS DOWN BLUE RIDGE BEHIND THE ONGOING
COVERAGE BEFORE BEEFING UP OUT EAST MID/LATE AFTERNOON AS CAPES
RECOVER LATE TO 1-2K J/KG. HIGH TEMPS WILL AGAIN GET OFF TO A
SLOW START IN SPOTS WITH LATE DAY HIGHS MOST SPOTS PENDING ADDED
SHRA/TSRA WITH PERHAPS THE FAR WEST BEING THE WARMEST WITH MORE
SUN EARLIER BEHIND THE CURRENT COVERAGE.
PREVIOUS VALID DISCUSSION...
AN UPPER LEVEL TROUGH OF LOW PRESSURE IS MOVING THROUGH THE GREAT
LAKES WITH LOBE OF VORTICITY TRAILING SOUTH INTO THE OHIO VALLEY.
THIS FEATURE HAS RESULTED IN A PERSISTENT AREA OF LIFT ASSOCIATED
WITH SHOWERS AND THUNDERSTORMS. AS OF 08Z/4AM...NUMEROUS SHOWERS
AND STORMS WERE OCCURRING FROM WESTERN PA INTO EASTERN OHIO AND
NORTHEAST KY. OUTFLOW FROM THIS COMPLEX OF THUNDERSTORMS IS
EXPECTED TO MAKE ITS WAY OVER THE MOUNTAINS TODAY.
MODELS DO NOT SEEM OVERLY CONFIDENT THIS OUTFLOW WILL MAKE IT
OVER THE MOUNTAINS...INDICATING WEAKENING AND A GRADUAL DEMISE OF
ACTIVITY. MATTER OF FACT THE SYNOPTIC MODELS DON`T PRODUCE MUCH IN
THE WAY OF RAINFALL AT ALL ACROSS OUR CWA...MOS POPS GENERALLY LESS
THAN 40 PERCENT.
ATTM PREFER NOT TO IGNORE THE OBVIOUS...WHICH IS A MODEST LOOKING
UPPER LEVEL TROF...ASSOCIATED WITH A HEALTHY LOOKING AREA OF
SHRA/TSRA...THE OUTFLOW OF WHICH SHOULD PASS THROUGH OUR FORECAST
AREA TODAY. THE ONLY THING THAT KEPT ME FROM GOING WITH
CATEGORICAL POPS IS THE POTENTIAL TIMING OF THE ACTIVITY AS IT
CROSSES THE MOUNTAINS. BASED ON CURRENT PROGRESSION...SHOWERS WILL
MOVE INTO THE WV MOUNTAINS DURING THE MORNING...THEN PROGRESS EAST
REACHING THE BLUE RIDGE TOWARD NOON...THEN EAST OF THE MTNS EARLY
THIS AFTERNOON. THIS EARLIER SORT OF TIMING SUGGESTS DEBRIS CLOUDS
WILL OVERSPREAD THE CWA EARLY AND LIMIT FULL INSOLATION THUS
LIMITING INSTABILITY.
THAT SAID...THINK AREA OF SHOWERS WITH EMBEDDED THUNDER WILL
CROSS THE FORECAST AREA...BUT IN A WEAKENED STATE. GREATEST
COVERAGE WILL BE FROM THE VIRGINIAS NORTHWARD CLOSER TO THE UPPER
SUPPORT FROM THE SHORT WAVE TROUGH...THE STRONGER DYNAMIC LIFT
MOVING FROM THE OHIO VALLEY INTO PA/NY. HAVE PLACED THE HIGHEST
POPS ACROSS WV/VA CLOSER TO THE SUPPORT FROM THE UPPER TROF...AND
WHERE THE OUTFLOW WILL HAVE THE BEST CHANCE OF MAKING IT OVER THE
MOUNTAINS AND HELP FOCUS RENEWED DEEP CONVECTION. FARTHER
SOUTH...FROM THE VA/NC BORDER SOUTHWARD...COVERAGE WILL BE LESS
AND MORE SCATTERED IN NATURE. WITH LESS COVERAGE COMES THE
OPPORTUNITY FOR MORE SUN. MORE SUN SUGGESTS WARMER
TEMPERATURES...AND WARMER TEMEPERATURES WILL YIELD GREATER
INSTABILITY PROVIDING STRONGER UPDRAFTS. AS SUCH CAN`T RULE OUT A
STRONG PULSE STORM OR TWO...ESPECIALLY WHERE MORE SUN
MATERIALIZES.
WENT BLO MOS GUIDANCE FOR TEMPERATURES ACROSS THE VIRGINIAS WHERE
MORE CLOUD COVER IS ANTICIPATED TODAY. THE WARMEST TEMPERATURES
WILL BE ACROSS NORTH CAROLINA WHERE MORE SUN IS ANTICIPATED.
PASSAGE OF THE UPPER TROUGH WILL BRING AN END TO MOST OF THE STORM
ACTIVITY THIS EVENING...FOLLOWED BY ANOTHER FOGGY NIGHT WITH
AREAS OF FOG AND PATCHY DENSE FOG DEVELOPING ACROSS THE FORECAST
AREA. IF SKIES CAN COMPLETELY CLEAR...THIS WOULD BE MOST IDEAL FOR
RADIATION FOG. THERE WERE SEVERAL REPORTS IN THE NEW RIVER VALLEY
WITH DENSE FOG EARLY WEDNESDAY MORNING. THINK IT WILL BE A REPEAT
AGAIN EARLY THURSDAY MORNING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
AS OF 330 AM WEDNESDAY...
THE REGION WILL REMAIN IN AN ACTIVE WEATHER PATTERN DURING THIS
PORTION OF THE FORECAST. A STRONG UPPER HIGH PRESSURE WILL BE
SITUATED ACROSS THE MID-MISSISSIPPI VALLEY. A DEEPENING UPPER
LOW/TROUGH WILL BE POSITIONED OFF THE COAST OF NEW ENGLAND. OUR AREA
OF THE COUNTRY WILL BE SANDWICHED BETWEEN THE TWO WITHIN NW-SE
ORIENTED MID-LEVEL BAROCLINIC ZONE...WITH AN ASSOCIATED SURFACE
BACKDOOR COLD FRONT EITHER OVER...OR VERY CLOSE TO THE REGION BY THE
START OF THE WEEKEND.
THE ABOVE SCENARIO POINTS TOWARD A PERIOD WITH AT LEAST SCATTERED
SHOWERS IN THE FORECAST EACH DAY AND NIGHT...AND SOME AFTERNOON AND
EVENING STORMS. WHAT IS A LITTLE HARDER TO NAIL DOWN WILL BE THE
WINDOWS OF OPPORTUNITY FOR LIKELY TO CATEGORICAL CHANCES OF
PRECIPITATION IN ASSOCIATION WITH PERIODICAL UPPER LEVEL SHORTWAVE
TROUGHS HEADING SOUTHEAST ALONG THIS BAROCLINIC ZONE AND THROUGH OUR
REGION. EACH MODEL SEEMS TO HAVE A DIFFERENT TAKE ON TIMING AND
TRACK.
EYEBALLING A CONSENSUS OF THE GUIDANCE POINTS TOWARD THURSDAY
AFTERNOON AND EVENING AS ONE POTENTIAL TIME THAT WOULD WARRANT
HIGHER POPS...ESPECIALLY ACROSS THE WESTERN AND NORTHERN PARTS OF
THE REGION. ANOTHER OPPORTUNITY MAY BE FRIDAY NIGHT ACROSS MAINLY
NORTHERN AND EASTERN PARTS OF THE AREA. FINALLY...SATURDAY NIGHT MAY
PROVE TO BE A THIRD OPPORTUNITY FOR ALL OF THE REGION...ESPECIALLY
CENTRAL AND WESTERN PORTIONS.
AT THIS TIME...CONFIDENCE IS NOT THERE TO OFFER A CATEGORICAL...75
PERCENT OR HIGHER...CHANCE OF PRECIPITATION FOR ANY ONE OF THE THREE
SCENARIOS LISTED ABOVE. HOWEVER...WILL CONTINUE...OR ADD...A
FORECAST OF LIKELY POPS TO THE FIRST AND SECOND SCENARIOS. FOR THE
THIRD SCENARIO...WILL OFFER A FORECAST JUST SHY OF LIKELY POPS.
TEMPERATURES THROUGH THE PERIOD ARE EXPECTED TO GRADUALLY COOL AS
THE BAROCLINIC ZONE MAKES PROGRESS WESTWARD. THE COMBINATION OF MORE
CLOUD COVER AND MORE PRECIPITATION...ALONG WITH LOWER HEIGHTS WILL
CONTRIBUTE TO THIS. BY SATURDAY...THE SURFACE COLD FRONT MAY BE
BISECTING THE REGION FROM NW-SE...THUS YIELDING NOTABLY COOLER
TEMPERATURES AT LEAST FOR THE CENTRAL AND NORTHEAST PARTS OF THE
AREA.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 130 PM EDT TUESDAY...
THE WEEKEND THROUGH EARLY NEXT WEEK WILL BE CHARACTERIZED BY THE
BATTLE BETWEEN LARGE UPPER RIDGE TO OUR WEST TRYING TO BUILD INTO
SOUTHERN APPALACHIANS...WHILE TROUGH OFF NEW ENGLAND COAST DEEPENS
WHILE CLOSING OFF AND CONTINUES TO APPEAR THAT IT WILL SET UP CLOSE
ENOUGH TO COAST TO PUSH BACK DOOR FRONT THROUGH AND WELL SOUTH OF
THE AREA THROUGH THE WEEKEND...BEFORE LIKELY WEAKENING AND ALLOWING
MORE INFLUENCE OF THE RIDGE TO BE FELT BY TUES...ESPECIALLY ACROSS
WESTERN PARTS OF THE AREA IF WEAK/SHALLOW BOUNDARY LAYER WEDGE IS IN
PLACE EARLY IN THE DAY BEFORE MIXING OUT OVER THE EAST. WHILE
SURFACE WEDGE FRONT MAY BE WELL TO THE SOUTH DURING MUCH OF THIS
PERIOD...WITH STRONGEST SOUTHWARD PUSH ON SATURDAY...THE 850
BOUNDARY AND MOST LIKELY TRACK FOR UPPER S/WV ENERGY FROM THE NW IS
LIKELY TO BE RIGHT OVER THE BLACKSBURG FORECAST AREA...AND THUS GOOD
CHANCE FOR SHOWERS/THUNDERSTORMS THROUGH THIS ENTIRE PERIOD. TIMING
MOST LIKELY WINDOWS REMAINS TRICKY...AS MANY OF THESE WAVES ARE
STRONGLY INFLUENCE BY CONVECTIVE COMPLEXES THAT WILL DEVELOP WELL
UPSTREAM. LIKE THE TRENDS OVERALL THAT 12Z GFS IS TAKING...NOT ONLY
WITH RETURN TO SHARPER AMPLITUDE PATTERN...BUT IDEA OF TWO DISTINCT
WAVES HEADING FOR THE WESTERN PART OF OUR FORECAST AREA...ONE
SATURDAY AND ANOTHER ONE SUNDAY. EXACT TIMES MAY HELP DETERMINE IF
THERE WILL BE ENOUGH INSTABILITY...WHICH WOULD LIKELY BE LIMITED TO
THE FAR WEST NEAR EDGE OF WEDGE BOUNDARY...BUT PERHAPS THE BIGGER
CONCERN IS RAINFALL THAT IS LIKELY TO IMPACT THE SAME AREAS AT LEAST
A COUPLE OF DAYS IN A ROW.
THERE COULD BE ANOTHER WAVE FOR MONDAY...BUT AS RIDGE ATTEMPTS TO
BUILD IN AND TROUGH TO THE EAST AND ASSOCIATED WEDGE WEAKEN WHAT MAY
TEND TO OCCUR IS MORE DIURNAL POP-UP CONVECTION ALONG AND NEAR THE
WESTERN PERIPHERY OF THE WEDGE BOUNDARY IN OUR WESTERN FORECAST AREA
AS THE ATMOS DESTABILIZES MORE. BY TUESDAY THE SUPPORT TO KEEP WEDGE
IN PLACE SHOULD BE WEAKENING AS TROUGH LIFTS AND SFC HIGH SHIFTS
MORE EAST OF THE AREA...AND OVERALL IT LOOKS A LITTLE DRIER...BUT
NOT SURE ALL POPS CAN BE REMOVED.
GIVEN PATTERN WE`VE BEEN IN...REALLY DON`T HAVE CONFIDENCE TO DRY IT
OUT OR WARM IT UP TOO FAST...SO WILL LEAN TOWARD STRONGER INFLUENCE
OF THE WEDGE THROUGH THIS PERIOD AND BETTER CHANCES FOR
PRECIP...WHICH WILL HELP STRENGTHEN THE WEDGE TOO. UNDERCUT EVEN
COOLER ECMWF A LITTLE BIT FOR HIGHS...WITH A BIT MORE WARMING FOR
TUESDAY. BUT IN THE FAR SOUTHWEST THINGS MAY BE ABLE TO WARM UP VERY
QUICKLY A DAY OR TWO EARLIER THAN THIS IF THE WEDGE CAN BREAK AND
SOME OF THE INFLUENCE OF THE BIG UPPER RIDGE CAN BE REALIZED. THIS
WILL EVENTUALLY RESULT IN A SIGNIFICANT WARM UP FOR OUR ENTIRE
AREA...BUT AM THINKING IT WILL NOT COME UNTIL MIDDLE OF NEXT WEEK.
&&
.AVIATION /17Z WEDNESDAY THROUGH SUNDAY/...
AS OF 100 PM EDT WEDNESDAY...
ACTIVE AND VARIABLE WEATHER PATTERN CONTINUES THIS TAF PERIOD.
EARLY CONVECTION WITHERED ON THE VINE AS IT MOVED OFF THE BLUE
RIDGE AND HELPED STABILIZE THE ATMOSPHERE FOR A BIT. HOWEVER...
LATEST ANALYSES INDICATE INSTABILITY IS RECOVERING AND MESO MODELS
DO SHOW SOME CONVECTIVE DEVELOPMENT DURING THE AFTERNOON. EASTERN
AREAS ARE ON THE FRINGE OF HIGH PRESSURE WEDGING DOWN THE COAST
WHERE THERE WAS EXTENSIVE LOW CLOUD COVER THIS MORNING. BELIEVE
CONDITIONS WILL GENERALLY BE VFR BY ISSUANCE TIME AND WILL USE
VICINITY TO COVER EXPECTED SHOWER/STORM DEVELOPMENT. CONDITIONS
WILL DIP DOWN WITH ANY PRECIPITATION BUT FEEL A TEMPO GROUP WILL
BE TOO HEAVY HANDED SO WILL LEAVE OUT MENTION OF LOWER CONDITIONS.
TONIGHT WILL BE ANOTHER TOUGH CALL FOR FOG/LOW STRATUS DEVELOPMENT.
INDICATIONS IN MESO RH FIELDS ARE THAT IFR/LIFR WILL BE LESS
WIDESPREAD SO WILL TRY TO CONFINE LOW CONDITIONS TO A SMALLER PERIOD
TOWARD DAYBREAK...JUST IN TIME TO MENTION SOME ADDITIONAL SHOWER
ACTIVITY WITH THE NEXT WAVE OF ENERGY ENTERING FROM THE WEST. WINDS
WILL NOT BE PROBLEMATIC FOR AVIATION PURPOSES THROUGH THIS TAF PERIOD.
EXTENDED AVIATION...
UPPER LEVEL DISTURBANCES WILL BE MOVING THROUGH PERIODICALLY AND
INTERACTING WITH A STATIONARY FRONT OVER THE AREA FOR THE NEXT
FEW DAYS...RESULTING IN PERIODS OF SHOWERS AND THUNDERSTORMS. DUE
TO THE HIGH MOISTURE CONTENT OF THE AIR...EXPECT STRATUS AND FOG
DURING THE OVERNIGHT PERIODS WITH AREAS OF MVFR/IFR MOST PRONOUNCED
BETWEEN MIDNIGHT AND 9AM EACH DAY. MODELS ARE INDICATED THAT A DEEPER
EASTERLY SORT OF WIND FLOW WILL SETUP FOR THIS UPCOMING WEEKEND.
THIS SUGGEST THAT LOW CIGS MAY PERSIST EVEN DURING THE DAYTIME
PERIODS...SATURDAY AND SUNDAY...WITH WIDESPREAD MVFR CONDITIONS
ACROSS THE AREA THIS WEEKEND DUE TO MOISTURE BANKING UP AGAINST THE
EAST SIDE OF THE APPALACHIANS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...SK
NEAR TERM...JH/PM
SHORT TERM...DS
LONG TERM...SK
AVIATION...MBS
AREA FORECAST DISCUSSION
NWS PORTLAND OR
220 PM PDT WED AUG 20 2014
.SYNOPSIS...NORTHWEST FLOW WILL CONTINUE OVER THE REGION FOR MUCH
OF THE WEEK. AN UPPER LEVEL LOW PRESSURE DROPPING SOUTHEAST ACROSS
THE INLAND NORTHWEST ON FRIDAY...COULD RESULT IN A SOME LIGHT
PRECIPITATION TO THE NORTHERN ZONES...AND A SLIM THREAT OF
THUNDERSTORMS ACROSS THE SOUTH WASHINGTON AND NORTH OREGON CASCADES.
NORTHWEST TO NORTH FLOW ALOFT CONTINUES OVER THE WEEKEND MAINTAINING
ONSHORE LOW-LEVEL FLOW AND NEAR NORMAL OR SLIGHTLY BELOW NORMAL
DAYTIME TEMPERATURES. HIGH PRESSURE STRENGTHENS JUST OFFSHORE EARLY
NEXT WEEK...WHICH MAY RESULT IN SOME LIGHT OFFSHORE LOW-LEVEL FLOW.
&&
.SHORT TERM...TONIGHT THROUGH SATURDAY...MORNING STRATUS LAYER HAS
TRANSFORMED INTO A BROKEN STRATOCUMULUS FIELD WITH CIGS GENERALLY 035
TO 045. MODERATE TO STRONG ONSHORE LOW-LEVEL FLOW CONTINUES TONIGHT
THROUGH THURSDAY...AND EXPECT SIMILAR DRIZZLE COVERAGE TONIGHT AND
THURSDAY MORNING COMPARED TO TODAY. SW WA LOWLANDS... OREGON
COAST...AND WEST SLOPES OF THE COAST RANGE SOME OF THE MORE FAVORED
DRIZZLE AREAS. KTTD-KDLS GRADIENT UP TO 4.0 MB AS OF 20Z...WHICH
NORMALLY RESULTS IN AT LEAST 25-30 MPH GUSTS NEAR HOOD RIVER.
AUGSPURGER...AN ELEVATED BPA SITE ON THE WASHINGTON SIDE OF THE
GORGE...GUSTING TO 35 MPH. EXPECT SIMILAR CONDITIONS THURSDAY.
MAIN FORECAST CHANGES CENTER ON LATE THURSDAY NIGHT THROUGH FRIDAY
PERIOD. LATEST NAM AND ECMWF CONTINUE TO INDICATE AREAS OF LIGHT QPF
FURTHER WEST THAN PREVIOUS COUPLE OF RUNS. BOTH MODELS SHOW THE UPPER
TROUGH DIGGING AS A REINFORCING SHORT-WAVE DROPS SOUTH INTO THE
TROUGH BASE...AIDED BY A 80-100 KT 300 MB JET STREAK. NAM SHOWS
FAIRLY ROBUST 700 MB OMEGA FOCUSED OVER SW WA AND EXTREME NW OREGON
12Z FRI. WOULD EXPECT A MUCH DEEPER MARINE LAYER WITH ENOUGH LIFT FOR
AT LEAST AREAS OF DRIZZLE LATE THU NIGHT THROUGH FRI MORNING IN THE
LOWLANDS AND POSSIBLY SPOTTY LIGHT SHOWERS OVER ELEVATED TERRAIN. ANY
DRIZZLE OR LIGHT SHOWERS SHOULD BE CONFINED TO THE NORTHERN
TWO-THIRDS OF THE FORECAST AREA.
THERE IS STILL SOME VARIABILITY AMONG THE MODEL SOLUTIONS WITH REGARD
TO THE ACTUAL LOW TRACK BUT MODELS GENERATE ENOUGH INSTABILITY OVER
THE S WA AND FAR N OREGON CASCADES FRI AFTERNOON FOR A SLIM THREAT OF
THUNDERSTORMS. ANY STORMS WHICH DO DEVELOP AND TRY TO MOVE WEST TO
SOUTHWEST OFF THE HIGHER TERRAIN WILL RUN INTO A MORE STABLE AIR MASS
OVERALL ON TOP OF THE ALREADY STABLE LOW LEVEL MARINE INFLUENCED LOW
LEVELS. CYCLONIC JET FROM THE DEPARTING LOW CLOSE ENOUGH TO THE
CASCADE CREST TO LEAVE SLIGHT CHANCE POPS THERE SAT...PRIMARILY IN
THE MORNING. WEISHAAR
.LONG TERM...SATURDAY NIGHT THROUGH TUESDAY...A SHORTWAVE ON THE
BACK SIDE OF THE TROUGH WILL PASS OVER OUR AREA SATURDAY
NIGHT...SEEN AT 500 AND 850 MB. THIS WILL ONLY BRING A SLIGHT CHANCE
OF RAIN IN THE NORTH OREGON AND SOUTHERN WASHINGTON CASCADES...AS
MOISTURE IS VERY LIMITED FROM NORTHERLY CONTINENTAL FLOW AND
NEGATIVE VORTICITY ADVECTION WILL PROMOTE DOWNWARD MOTION OVER THE
WESTERN 2/3 OF OUR AREA. AS THE LONGWAVE TROUGH PROGRESSES
EASTWARD...THE RIDGE CURRENTLY OVER A GOOD PORTION OF THE NORTH
PACIFIC WILL MOVE ONSHORE OVER THE WEST COAST WHICH WILL BRING
TEMPERATURES UP AND DRY CONDITIONS EARLY NEXT WEEK. -MCCOY
&&
.AVIATION...GENERALLY VFR CONDITIONS THIS AFTERNOON WITH SCT CLOUDS
AND SOME CIGS 3000 TO 4000 FT. CLEARING TREND WILL CONTINUE INTO
THE OVERNIGHT HOURS INLAND WHILE ONSHORE FLOW BRINGS MVFR CIGS
BACK TO COAST AFT 02Z. MARINE STRATUS WILL PUSH INLAND AGAIN
TONIGHT WITH CIGS AROUND 2500 FT BUT LATEST GUIDANCE SHOWS BEST
LIKELIHOOD ON THE NORTH SIDE OF THE RIVER. COULD SEE SOME
SCATTERED CLOUDS FARTHER SOUTH IN THE VALLEY BUT GENERALLY VFR
CONDITIONS SHOULD PREVAIL SOUTH OF PDX.
KPDX AND APPROACHES...VFR WITH CLEARING SKIES THIS AFTERNOON.
COULD SEE SOME MVFR CIGS AROUND 2500 FT THURSDAY MORNING AFTER
13Z BUT NOT AS WIDESPREAD AS THIS MORNING. BOWEN
&&
.MARINE...BUOYS SHOWING 4 TO 6 FT SEAS AT 10 SECONDS BUT THERE`S
ALSO ENERGY AT 8 SECONDS SO SEAS WILL BE A BIT STEEP THROUGH THIS
EVENING. NW WINDS REMAIN RATHER LIGHT...LESS THAN 15 KT. VERY
LITTLE CHANGE IN THE PATTERN THROUGH THE WEEKEND WITH CONTINUED NW
WIND AND SWELL. PRESSURE GRADIENT TIGHTENS SOME FRIDAY AND
SATURDAY AFTERNOONS AS HIGH PRESSURE OVER THE NE PACIFIC
STRENGTHENS A BIT WITH THERMAL LOW OVER NORTHERN
CALIFORNIA...INCREASING WINDS TO 15 TO 20 KT WITH SLIGHTLY HIGHER
GUSTS. BOWEN
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...NONE.
&&
$$
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.
Area Forecast Discussion
National Weather Service Spokane WA
1120 AM PDT WED AUG 20 2014
.SYNOPSIS...
Cooler temperatures and the occasional threat of showers and
thunderstorms will linger the rest of the week and into the
weekend. However, the vast majority of this precipitation will be
in the North Idaho Panhandle.
&&
.DISCUSSION...
Forecast update to increase precip chances across the northern
mountains for this afternoon. Some residual elevated convection
is continuing to march eastward along the Canadian border in the
Northern Panhandle late this morning. This is expected to push
across some thunderstorms near Bonners Ferry and Porthill. Once
this cloud cover associated with the nocturnal convection clears
the region, we will see a redevelopment of showers and
thunderstorms over the higher terrain from west to east. This set
up looks very similar to what happened yesterday. The HRRR model
has been consistent with thunderstorms developing over the East
Slopes of the Northern Cascades into the Okanogan Highlands around
noon. These storms will generally push to the east at approximately
20 mph through the afternoon. A redevelopment of thunderstorms
today will be more toward the mid and late afternoon hours for the
Northeast Mountains and the Northern Panhandle. Looks like there
will be a slight northwesterly component to the steering flow for
these thunderstorms today, so the northern Upper Columbia Basin to
the Spokane/Coeur d`Alene corridor will see a chance for isolated
to scattered thunderstorms as well. Thunderstorms are expected to
hold off for the Spokane/Coeur d`Alene corridor until the late
afternoon and evening hours.
The 12Z model runs continue to show upwards of 700-1000 J/KG of
surface based CAPE across the northern mountains this afternoon.
The 0-6 km bulk shear will be slightly stronger today at around
20 kts or so. This shear is still a bit weak for much in the may
of concern for strong to severe thunderstorms; however, we did see
a storm pulse up quickly to severe levels yesterday over the
northern Upper Columbia Basin in a weakly sheared environment, so
it will not be out of the realm of possibility today as well. Due
to the weak shear though, thunderstorms will be of the pulse
variety. Any stronger storms that due develop will likely collapse
fairly quickly. I did add small hail, heavy rain, and frequent
lightning to the forecast across the northern mountains today
considering that these impacts were observed with the thunderstorm
activity yesterday. /SVH
&&
.AVIATION...
18Z TAFS: An are of isolated thunderstorm activity will track
across the Northern Panhandle late this morning. A resurgence of
thunderstorms is expected across the northern mountains today once
we warm to our convective temperature. These thunderstorms are
expected to push into the vicinity of KGEG, KSFF and KCOE by late
this afternoon and early evening. Impacts from convection today
will include: outflow winds up to 35 mph, small hail and brief
downbursts of heavy rain. Showers and thunderstorms will wind down
after 06Z this evening. /SVH
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 80 56 79 52 75 52 / 20 40 10 10 20 30
Coeur d`Alene 79 55 77 50 74 50 / 10 50 10 10 30 40
Pullman 80 50 79 46 76 51 / 10 0 10 10 20 40
Lewiston 85 59 85 57 83 58 / 10 0 0 0 20 30
Colville 76 54 79 52 78 50 / 70 50 50 50 40 30
Sandpoint 77 52 73 51 72 50 / 60 60 50 50 50 30
Kellogg 75 53 73 51 71 49 / 20 40 20 20 40 50
Moses Lake 86 56 84 53 82 56 / 0 0 10 10 20 20
Wenatchee 84 60 83 59 80 59 / 0 0 10 10 20 20
Omak 86 59 84 55 80 55 / 40 20 20 40 30 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
330 PM MDT WED AUG 20 2014
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 330 PM MDT WED AUG 20 2014
CURRENT KCYS RADAR LOOP SHOWS SHOWERS AND FEW THUNDER SHOWERS
DEVELOPING OVER THE MOUNTAINS AND THE CHEYENNE RIDGE THIS
AFTERNOON...AND SLOWLY MOVING EASTWARD. ACTIVITY HAS BEEN WEAK
WITH ONLY A FEW ISOLATED LIGHTNING STRIKES. EXPECT THIS ACTIVITY
TO CONTINUE THROUGH INTO LATE THIS AFTERNOON AND EARLY THIS
EVENING WHILE DEVELOPING FURTHER EAST INTO THE HIGH PLAINS OF
SOUTHEAST WYOMING. EXPECT ANY THUNDERSTORMS TO QUICKLY DIMINISH
AROUND SUNSET.
THUNDERSTORM COVERAGE WILL LIKELY BE LOWER ON THURSDAY ACROSS MOST
OF THE FORECAST AREA AS WARMER AIR ALOFT MOVES INTO THE AREA AND
500MB HEIGHTS INCREASE THROUGH THE DAY. A COLD FRONT BOUNDARY WILL
BECOME MORE NOTICEABLE FURTHER NORTH ACROSS MONTANA AND NORTHERN
WYOMING AS IT SLOWLY DRIFTS SOUTHWARD THROUGH THE DAY.
THEREFORE...EXPECT THE BEST COVERAGE OF SHOWERS AND THUNDERSTORMS
TO BE ACROSS THE MOUNTAINS AND WELL NORTH OF I80. CAN NOT RULE OUT
A THUNDER SHOWER OR TWO ALONG THE I80 CORRIDOR DURING THE EVENING
HOURS. TEMPERATURES WILL REMAIN NEAR NORMAL AND GENERALLY IN THE
UPPER 70S WEST OF THE LARAMIE RANGE AND LOW 80S TO LOW 90S ACROSS
THE EASTERN PLAINS.
THIS PERSISTENT WEATHER PATTERN WILL BEGIN TO CHANGE ON FRIDAY AND
ESPECIALLY THIS WEEKEND. MODELS INDICATE A PRETTY STRONG COLD
FRONT FOR THIS TIME OF THE YEAR PUSHING SOUTHWARD INTO SOUTHEAST
WYOMING. THIS FRONT WILL STALL SOMETIME ON FRIDAY AND BE THE MAIN
FOCUS FOR SCATTERED TO NUMEROUS SHOWERS AND TSTORMS AS AN UPPER
LEVEL TROUGH FROM WESTERN CANADA MOVE SOUTH AND EVENTUALLY
EASTWARD INTO IDAHO. LOWERED MAX AND MIN TEMPERATURES FRIDAY AND
FRIDAY NIGHT AND INCREASED POP BETWEEN 25 TO 45 PERCENT ACROSS THE
HIGH PLAINS...AND NEAR 70 PERCENT OVER THE MOUNTAINS.
.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 330 PM MDT WED AUG 20 2014
BOTH THE GFS AND ECMWF BRING A SHORTWAVE THROUGH THE AREA IN
SOUTHWEST WIND FLOW FRIDAY NIGHT INTO SATURDAY. ECMWF ROUGHLY 12
HOURS SLOWER THAN THE GFS...BUT BOTH ARE IN CLOSE AGREEMENT WITH
MOVEMENT OF FIRST DISTURBANCE...THEN MOVING THE MAIN TROUGH
THROUGH ON SATURDAY/SATURDAY NIGHT. JUST ABOUT EVERYONE SHOULD SEE
SHOWERS/THUNDERSTORMS DURING THE DAY SATURDAY WITH BEST CHANCES
FOR THE PANHANDLE SATURDAY NIGHT. MAIN SHORTWAVE THROUGH THE AREA
BY SUNDAY...WITH MAINLY ISOLATED SHOWERS OVER THE MOUNTAINS.
NEXT COLD FRONT LOOKS TO MOVE INTO THE AREA MONDAY AFTERNOON INTO
TUESDAY. ECMWF A LITTLE COLDER THAN GFS IN 700MB
TEMPERATURES...BUT NOT AS BAD AS A FEW DAYS AGO. PROBABLY NEED TO
GO COLDER WITH THIS SETUP. DISCREPANCY MUCH GREATER ON TUESDAY
WITH THE ECMWF FORECASTING 700MB TEMPERATURES OF +4 TO +6C AND GFS
SHOWING +10 TO +12C.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY MORNING)
ISSUED AT 330 PM MDT WED AUG 20 2014
FOLLOWED LATEST HRRR GUIDANCE FOR TIMING ON SHOWERS AND
THUNDERSTORMS FOR SOUTHEAST WYOMING AND NEBRASKA PANHANDLE
AIRPORTS THIS AFTERNOON. HRRR HAS BEEN DOING WELL ON THE EARLY
MORNING CONVECTION...SO SEE NO REASON TO DEVIATE.
&&
.FIRE WEATHER...
ISSUED AT 156 PM MDT WED AUG 20 2014
MINIMAL FIRE WEATHER CONCERNS INTO EARLY NEXT WEEK. SUBTROPICAL
MOISTURE WILL REMAIN OVER THE AREA THROUGH THE WEEKEND WITH
SHOWERS AND THUNDERSTORMS POSSIBLE EACH DAY ACROSS SOUTHEAST
WYOMING AND WESTERN NEBRASKA. THERE IS A GOOD CHANCE OF WETTING
RAINS BY FRIDAY AND THIS WEEKEND AS THUNDERSTORM COVERAGE WILL BE
HIGHER. TEMPERATURES WILL TREND COOLER BY LATE THIS WEEK AND INTO
THIS WEEKEND AS A STRONG COLD FRONT FOR THIS TIME OF THE YEAR
MOVES INTO THE REGION LATE ON SATURDAY.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM...TJT
LONG TERM...CLAYCOMB
AVIATION...CLAYCOMB
FIRE WEATHER...TJT
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1034 AM MDT WED AUG 20 2014
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 350 AM MDT WED AUG 20 2014
INITIAL SHORTWAVE TROUGH ALOFT MOVES ACROSS OUR COUNTIES
EARLY IN THE DAY...WITH A WEAKER...SECONDARY SHORTWAVE TROUGH
APPROACHING OUR WESTERN COUNTIES IN THE LATE AFTERNOON. SOME LOW
LEVEL DRYING NOTED IN THE WAKE OF THE MORNING SHORTWAVE TROUGH...
THOUGH IT APPEARS THERE WILL BE ENOUGH LOW AND MID LEVEL MOISTURE
THIS AFTERNOON TO SPARK ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS...MOST NUMEROUS WEST OF INTERSTATE 25.
TONIGHT...SHOWERS AND THUNDERSTORMS ENDING IN THE EVENING WITH THE
LOSS OF DAYTIME HEATING AND ABSENCE OF ANY OTHER LIFTING MECHANISMS.
THURSDAY...SOUTHWEST FLOW ALOFT CONTINUES AND WITH ADEQUATE LOW AND
MID LEVEL MOISTURE IN PLACE...WILL SEE ISOLATED LATE DAY
THUNDERSTORMS ALONG AND WEST OF A LUSK TO CHEYENNE LINE.
THURSDAY NIGHT...WEAK COLD FRONT ENTERS FROM THE NORTH...THOUGH WITH
MINIMAL LOW AND MID LEVEL MOISTURE...RAIN CHANCES WILL BE SLIM. LATE
IN THE NIGHT...WILL GO WITH ISOLATED SHOWERS AFTER MIDNIGHT EAST OF
A DOUGLAS TO SIDNEY LINE IN LOW LEVEL CONVERGENCE BOUNDARY.
FRIDAY...INCREASED CHANCE FOR SHOWERS AND THUNDERSTORMS OVER
THURSDAY AS A NEGATIVELY TILTED SHORTWAVE TROUGH ALOFT PROPAGATES
ACROSS OUR WESTERN NEBRASKA COUNTIES...WITH ENHANCED SOUTHEAST LOW
LEVEL WINDS ADVECTING MOISTURE IN...AND PROVIDING MECHANICAL LIFT TO
HELP GENERATE THUNDERSTORMS.
.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 350 AM MDT WED AUG 20 2014
00Z MEDIUM RANGE GUIDANCE ARE CONSISTENT IN SWINGING AN UPPER
TROUGH THRU THE NRN ROCKIES OVR THE WEEKEND. THIS IS AN EARLY
INDICATION OF THE SEASONAL PATTERN CHANGE THAT WILL CONTINUE OVR
THE NEXT FEW MONTHS. SATURDAY STILL LOOKS RELATIVELY WARM IN THE
PREFRONTAL AIR MASS...ESPECIALLY OVR THE ERN PLAINS. MODELS PROG
1000-1500 J/KG AHEAD OF THE FRONT SATURDAY AFTERNOON. THE
FAVORABLE THERMODYNAMIC PROFILE COMBINED WITH THE PROXIMITY OF RRQ
OF A JET STREAK SUGGESTS AT LEAST THE POSSIBILITY OF A FEW
STRONGER STORMS OVR THE PLAINS SATURDAY AFTERNOON. OF
COURSE...MUCH OF THIS SCENARIO IS DEPENDENT UPON THE CURRENT
TIMING OF LATE SATURDAY AND SATURDAY EVENING FROPA. CONVECTION
WILL TURN MORE SHOWERY IN THE WAKE OF THE FRONT SATURDAY NIGHT.
SUNDAY WILL BE NOTICEABLY COOLER POST-FRONTAL WITH HIGHS ONLY
REACHING 70S AT MOST LOCATIONS. LEFT MOSTLY SHOWER CHANCES ALONG
WITH ISOLD THUNDER MENTION GOING FOR SUNDAY. THIS WILL DEPEND UPON
JUST HOW MUCH CLEARING OCCURS. TEMPERATURES RETURN TO MORE
SEASONAL VALUES FOR MON-TUE TIMEFRAME. HARD TO REMOVE MENTION OF
DAILY AFTERNOON AND EVENING CONVECTION EARLY NEXT WEEK AS
PERSISTENT SOUTHWEST FLOW EJECTS IMPOSSIBLE TO TIME EMBEDDED
SHORTWAVES. PRECIP DEFINITELY WONT BE AN ALL DAY OCCURRENCE...BUT
CANT RULE OUT ITS POSSIBILITY MAINLY DURING THE AFTERNOON AND
EVENING HOURS. THE PATTERN LOOKS TO TREND DRIER FOR THE LATTER
HALF OF NEXT WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY MORNING)
ISSUED AT 1033 AM MDT WED AUG 20 2014
FOLLOWED LATEST HRRR GUIDANCE FOR TIMING ON SHOWERS AND
THUNDERSTORMS FOR SOUTHEAST WYOMING AND NEBRASKA PANHANDLE
AIRPORTS THIS AFTERNOON. HRRR HAS BEEN DOING WELL ON THE EARLY
MORNING CONVECTION...SO SEE NO REASON TO DEVIATE.
&&
.FIRE WEATHER...
ISSUED AT 350 AM MDT WED AUG 20 2014
HUMIDITIES AND WINDS WILL REMAIN BELOW CRITICAL THRESHOLDS THE
NEXT FEW DAYS...THUS MINIMAL FIRE WEATHER CONCERNS.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM...RUBIN
LONG TERM...HAHN
AVIATION...CLAYCOMB
FIRE WEATHER...RUBIN