Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/18/13
AREA FORECAST DISCUSSION
NWS TUCSON AZ
922 PM MST SUN SEP 15 2013
.SYNOPSIS...THERE WILL BE ENOUGH MOISTURE FOR ISOLATED TO SCATTERED
THUNDERSTORMS MAINLY EAST OF TUCSON TO START THE WEEK. THE DRIER
WESTERLY FLOW WILL CONTINUE TO DIMINISH MOISTURE THROUGH THE
WEEK...BUT WE MAY HOLD ON TO ENOUGH TO KEEP A FEW MOUNTAIN
THUNDERSTORMS AROUND IN THE AFTERNOONS.
&&
.DISCUSSION...WATER VAPOR IMAGER SHOWS THE WEAK TROUGH EXTENDING
FROM WESTERN COLORADO AND ALONG THE ARIZONA/NEW MEXICO BORDER...WITH
RADAR MOSAIC DETECTING ONLY A FEW SHOWERS AND THUNDERSTORMS
REMAINING OVER THE REGION...MAINLY FROM WHETSTONE TO SIERRA VISTA...
BUT ALSO JUST EAST OF THE ARIZONA BORDER IN WEST CENTRAL NEW MEXICO.
MEANWHILE...A LARGE AREA OF HIGH PRESSURE COVERS THE EASTERN PACIFIC
WATERS...WEST OF THE CENTRAL BAJA PENINSULA.
THE SHOWERS AND STORMS SHOULD GRADUALLY TAPER OFF THROUGH THE LATE
EVENING AND OVERNIGHT HOURS WITH MOSTLY CLEAR TO PARTLY CLOUDY SKIES
ACROSS THE REGION. WILL LEAVE SOME SINGLE DIGIT AND SLIGHT CHANCE
POPS IN THE FORECAST...MAINLY ALONG THE AZ/NM BORDER OVERNIGHT.
OTHERWISE...A DRY FORECAST IN STORE ELSEWHERE FOR THE REST OF
TONIGHT.
AS OF 04Z (9 PM MST)...TEMPERATURES ACROSS THE REGION RANGED FROM
THE LOWER 70S TO THE LOWER 90S...WITH THE TUCSON INTL AIRPORT
REPORTING A TEMP OF 92 DEGS AFTER REACHING AN AFTERNOON HIGH OF 100
DEGS. THESE READINGS SEEM TO BE ON TRACK WITH THE EXPECTED OVERNIGHT
LOWS...SO NO CHANGES ARE PLANNED AT THIS TIME...BUT WILL CONTINUE TO
MONITOR AND WILL MAKE ADJUSTMENTS IF NEEDED.
FOR DETAILS REGARDING THE FORECAST BEYOND TONIGHT...PLEASE REFER TO
THE PREVIOUS DISCUSSION BELOW. ALSO SEE THE HYDROLOGY SECTION FOR
INFO REGARDING HIGH WATER LEVELS EXPECTED ON THE GILA RIVER TONIGHT
AND MONDAY.
&&
.AVIATION...VALID THRU 17/00Z.
WEST OF KTUS MOSTLY CLEAR. KTUS EWD/SWD ISOLD-SCT -TSRA/-SHRA THIS
EVENING...AND A FEW -TSRA/-SHRA MAINLY NEAR THE NEW MEXICO BORDER
LATE TONIGHT. OTHERWISE...FEW-SCT CLOUDS MAINLY AT 8-10K FT AGL THIS
EVENING AND OVERNIGHT. SURFACE WIND GENERALLY OUT OF THE EAST AT
5-15KTS AND GUSTY AT TIMES INTO MONDAY. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...EXPECT ISOLATED TO SCATTERED THUNDERSTORMS MAINLY
EAST OF TUCSON THROUGH TUESDAY. SOME DRYING THROUGH THE WEEK BUT WE
MAY HOLD ON TO ENOUGH MOISTURE FOR ISOLATED MOUNTAIN
THUNDERSTORMS...ESPECIALLY NEAR THE INTERNATIONAL BORDER. GUSTY EAST
WINDS AT TIMES THROUGH TUESDAY. OTHERWISE...DAYTIME TEMPERATURES
WILL BE A FEW DEGREES ABOVE NORMAL THIS WEEK.
&&
.HYDROLOGY...THE SAN FRANCISCO RIVER AT CLIFTON CRESTED AT 24.1 FEET
AT 1045 AM MST...BUT HAS SINCE FALLEN TO 18.0 FEET AS OF 5:00 PM
MST. THE RIVER IS EXPECTED TO CONTINUE TO GRADUALLY FALL THIS
EVENING. THEREFORE...THE FLOOD WARNING FOR THE SAN FRANCISCO RIVER
AT CLIFTON WILL BE ALLOWED TO EXPIRE AT 9 PM MST.
THE FLOWS FROM THE SAN FRANCISCO HAVE MOVED INTO THE GILA RIVER
WHICH WILL REMAIN ABOVE BANKFULL AT SOLOMON BUT BELOW MINOR FLOOD
STAGE. AS OF 7:15 PM MST...THE STAGE ON THE GILA RIVER AT SOLOMON
WAS 15.5 FT WITH A FLOW NEAR 22700 CFS. AT THIS LEVEL THE SOLOMON
ROAD BRIDGE APPROACHES BECOME FLOODED. COUNTY OFFICIALS IN GRAHAM
COUNTY HAVE CLOSED THE SOLOMON ROAD BRIDGE AND SANCHEZ ROAD. IT ALSO
MEANS FLOODING OF LOW LYING AGRICULTURAL AREAS NEAR THE RIVER IS
POSSIBLE.
THE GILA RIVER AT GILA NEW MEXICO CRESTED AT A STAGE OF 12.9 FT AND
A FLOW OF NEAR 29000 CFS AS OF 6:30 PM MST. WHILE RISES WILL OCCUR
DURING THE OVERNIGHT AND EARLY MORNING HOURS ON THE GILA RIVER AT
DUNCAN...SOUTH OF CLIFTON AND SOLOMON...THE RIVER SHOULD REMAIN
BELOW BANKFULL LATE TONIGHT AND INTO MONDAY BUT THE FLOOD ADVISORY
WILL BE EXTENDED IN AREAL COVERAGE TO INCLUDE AREAS ALONG THE GILA
AS FAR WEST AS CALVA AND ALSO TO EXTEND THE ADVISORY THROUGH AROUND
MID MORNING MONDAY.
&&
.PREVIOUS DISCUSSION...LATEST HRRR CONTINUES NEAR SURFACE
STREAMLINES FROM NEW MEXICO INTO EASTERN ZONES INTO EARLY MONDAY.
THIS WILL PROBABLY HELP KEEP ISOLATED TO LOW END SCATTERED
CONVECTION GOING MAINLY EAST OF TUCSON WITH AN EMPHASIS ON THE
MOUNTAINS.
LATEST NAMDNG5 CONTINUES EASTERLY SURFACE WINDS INTO TUESDAY AS FAR
WEST AS TUCSON...UP TO BREEZY LEVELS AT TIMES. THIS COULD CAUSE
PROBLEMS WITH OVERNIGHT LOWS IN A COUPLE OF LOCATIONS WITH THE
POTENTIAL FOR THE BOUNDARY LAYER TO REMAIN MIXED AND KEEP
TEMPERATURES UP A BIT. AT THAT POINT THE LOWER LEVEL FLOW STARTS TO
STACK MORE NEATLY AND ADDITIONAL DRYING WILL PROBABLY SEE EVEN
EASTERN MOUNTAINS LOSING THUNDERSTORMS WITH A BELOW 10 PERCENT
FORECAST AREA WIDE BY WEDNESDAY.
SOME MOISTURE PUSH FROM THE TROPICS INTO SONORA AND CHIHUAHUA IS
EXPECTED LATER IN THE WEEK...BUT IS STILL EXPECTED TO HAVE
DIFFICULTY MAKING MUCH PROGRESS FURTHER NORTH WITH THE UNFAVORABLE
WESTERLY FLOW. A WEAK SHORTWAVE RIDGE COULD ALLOW ENOUGH OF A BREAK
IN THE FLOW FOR AREAS MAINLY NEAR THE INTERNATIONAL BORDER TO SEE
ISOLATED CONVECTION AGAIN LATER IN THE WEEK.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...FLOOD ADVISORY FOR THE GILA RIVER
AT DUNCAN AND SOLOMON IN EFFECT THROUGH 10 PM MST THIS
EVENING.
&&
$$
VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
CURRENT DISCUSSION/HYDROLOGY...MOLLERE
PREVIOUS DISCUSSION...MEYER/DROZD
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
945 AM MDT MON SEP 16 2013
.UPDATE...
&&
.SHORT TERM...WATER VAPOR IMAGERY SHOWING UPPER LOW MOVING VERY
SLOWLY EAST ACROSS CENTRAL COLORADO WITH INDICATIONS OF SOME
DRYING OVER WESTERN COLORADO. PW VALUES FROM GPS ALSO SHOWING A
DECREASE WITH ABOUT A ONE TO TWO TENTHS DROP OF PW FROM FRONT
RANGE WESTWARD. STILL EXPECT MUCH LESS STORM COVERAGE TODAY WITH
THE DRYING FROM THE WEST...HOWEVER STORMS THAT DO DEVELOP COULD
STILL DROP SOME HEAVY RAIN. ACROSS LOWER ELEVATIONS...STILL QUITE
A BIT OF STRATUS WITH SOME BREAKS OCCURRING SOUTH AND WEST OF
DENVER. FOR MOST LOCATIONS TOO STABLE FOR SHOWERS ON THE NORTHEAST
PLAINS BUT MAYBE AN ISOLATED STORM OVER THE PALMDER DIVIDE AND
LOCATIONS CLOSER TO THE FOOTHILLS.
.AVIATION...LOW STRATUS WILL SHOW ONLY SLOW IMPROVEMENT DURING THE
LATE AM AND EARLY AFTERNOON WITH NOT A COMPLETE BREAKOUT OF
STRATUS UNTIL 21-22Z. MORE RAPID IMPROVEMENT LIKELY AT APA WITH
BETTER CLEARING ALREADY NOTED OVER DOUGLAS COUNTY. THERE IS A
WEAK CYLCONE OVER THE AREA WHICH SEEMS CENTERED OVER WESTERN ADAMS
AND MOVING EAST.
&&
.HYDROLOGY...WILL HOLD ONTO FLASH FLOOD WATCH BUT CERTAINLY STORM
COVERAGE WILL BE MUCH LESS TODAY. STILL WITH THE AMOUNT OF
MOISTURE IN THE AIR...HEAVY RAIN IS STILL POSSIBLE WITH STORMS
WITH AMOUNTS OVER AN INCH IN LESS THAN ONE HOUR. MAIN CONCERN
AREAS WILL BE THE FOOTHILLS OVER JEFFERSON...BOULDER AND LARIMER
COUNTIES AND AREAS WITH SATURATED SOILS.
&&
.PREV DISCUSSION... /ISSUED 337 AM MDT MON SEP 16 2013/
SHORT TERM...AREAS OF DRIZZLE AND FOG WERE OCCURRING EARLY THIS MORNING IN AND NR
THE FOOTHILLS. THIS ACTIVITY MAY LINGER THRU ABOUT 15Z BEFORE
STARTING TO LIFT.
FOR THIS AFTN THE WK UPPER LEVEL TROUGH WILL FINALLY BEGIN TO EXIT
NERN CO. ALTHOUGH THERE WILL BE DRYING ALOFT SMALL MID LVL COLD
POOL COMBINED WITH LINGERING PRECIPITABLE WATER VALUES AROUND AN
INCH COULD STILL LEAD TO ANOTHER ROUND OF SCT SHOWERS AND TSTMS OVER
THE HIGHER TERRAIN THIS AFTN. A FEW OF THE STORMS COULD PRODUCE
RAINFALL AMOUNTS UP TO AN INCH IN 30 MINUTES. WITH VERY SATURATED
CONDITIONS AND AFTER COORDINATION WITH EOC WILL ISSUE AN FFA FM
18Z- 01Z FOR THE FRONT RANGE FOOTHILLS AND ADJACENT PLAINS WEST OF
I-25 FM THE WY BORDER SOUTH TO THE WRN SUBURBS OF DENVER. AS FOR
AFTN HIGHS READINGS WILL BE WARMER OVER NERN CO WITH HIGHS MAINLY
IN THE LOWER TO MID 70S.
BY TONIGHT TSTM ACTIVITY SHOULD END RATHER QUICKLY BY SUNSET WITH NO
ADDITONAL PCPN OVERNIGHT.
LONG TERM...WEAK UPPER RIDGING AND ZONAL FLOW ALOFT ON TUESDAY
BECOMES SOUTHWESTERLY TUESDAY NIGHT INTO WEDNESDAY AS AN UPPER
TROUGH MOVES EASTWARD. THE UPPER TROUGH AXIS IS PROGGED OVER
WESTERN COLORADO BY 12Z THURSDAY. THE QG VERTICAL VELOCITY FIELDS
HAVE WEAK DOWNWARD MOTION PROGGED FOR THE CWA TUESDAY...THEN WEAK
UPWARD MOTION IS PROGGED LATE TUESDAY NIGHT THROUGH WEDNESDAY
NIGHT. LOW LEVEL TROUGHING IS PROGGED OVER THE PLAINS TUESDAY INTO
WEDNESDAY...WITH THE NORMAL DIURNAL WIND PATTERNS PARTLY USURPED
BY DOWNSLOPING. BY 12Z THURSDAY MORNING...A COLD FRONT IS EXPECTED
TO BE MOVING ACROSS THE FORECAST AREA. FOR MOISTURE...TUESDAY IS
PRETTY DRY...WITH A SLIGHT INCREASE OF MOISTURE ON WEDNESDAY.
PRECIPITABLE WATER VALUES OVER THE WESTERN PLAINS ARE 0.40 TO 0.70
INCH ON TUESDAY. THEY INCREASE THERE INTO THE 0.70 TO 0.90 INCH
RANGE TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. VALUES FURTHER EAST
ON THE PLAINS ARE A TAD HIGHER. THERE IS LIMITED CAPE PROGGED LATE
DAY TUESDAY...BUT IT INCREASES SOMEWHAT LATE DAY WEDNESDAY. THE
BOUNDARY LAYER DEW POINTS RANGE FROM THE MID 30S F OVER THE
WESTERN FORECAST AREA TO THE LOWER 50S EAST ALL FOUR PERIODS. THE
QPF FIELDS HAD A TAD OF MEASURABLE RAINFALL OVER THE MOUNTAINS
LATE DAY TUESDAY. THERE IS A SLIGHT BIT MORE LATE DAY WEDNESDAY
AND IT ALSO COVERS THE FOOTHILLS. WILL GO MINIMAL POPS LATE DAY
TUESDAY AND WEDNESDAY IN THE MOUNTAINS. FOR TEMPERATURES...
TUESDAY`S HIGHS ARE 3-6 C WARMER THEN TODAY`S. WEDNESDAY`S HIGHS
ARE SIMILAR TO TUESDAY`S. FOR THE LATER DAYS...THURSDAY THROUGH
SUNDAY...MODELS HAVE THE UPPER TROUGH MOVE ACROSS THE CWA ON
THURSDAY. THURSDAY NIGHT INTO SATURDAY MORNING...UPPER RIDGING
MOVES EASTWARD ACROSS THE FORECAST AREA. SOUTHWESTERLY FLOW ALOFT
THEN MOVES IN WITH THE NEXT UPPER TROUGH TO GET INTO COLORADO BY
SUNDAY NIGHT. MOISTURE IS SPARSE UNTIL SUNDAY. TEMPERATURES ARE
AROUND SEASONAL NORMALS THURSDAY AND FRIDAY...THEN ABOVE SATURDAY
AND SUNDAY.
AVIATION...WK DENVER CYCLONE WAS OVER DENVER EARLY THIS MORNING WITH
SOME AREAS OF FOG AND DRIZZLE. WILL KEEP LIFR CONDITIONS THRU 15Z
WITH IMPROVING CONDITIONS THERAFTER. FOR THIS AFTN THERE WILL BE A
SLIGHT CHC OF TSTMS HOWEVER FOR NOW WILL KEEP ACTIVITY TO THE WEST
AND SW OF DIA AND NOT MENTION IN THE TAF. WINDS THIS AFTN WILL BE
SSE ALTHOUGH THE RAP HAS THEM A BIT MORE ELY. FOR TONIGHT SHOULD
SEE WINDS BECOMING DRAINAGE WITH NO LOW CLOUDS OR FOG EXPECTED
OVERNIGHT.
HYDROLOGY...AFTER COORDINATION WITH EOC HAVE DECIDED TO ISSUE A FLASH
FLOOD WATCH FOR THE FOOTHILLS AND AREAS WEST OF I-25 FM 18Z-01Z.
THERE IS STILL A POTENTIAL FOR A FEW STORMS TO GENERATE RAINFALL
AMOUNTS UP TO AN INCH IN 30 MINUTES. WITH THE GROUND STILL VERY
SATURATED THIS COULD LEAD TO SOME LOCALIZED FLASH FLOODING IN A
FEW AREAS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 7 PM MDT THIS EVENING FOR COZ035-036-038-
039.
&&
$$
SHORT TERM...ENTREKIN
LONG TERM....RJK
AVIATION...ENTREKIN
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
337 AM MDT MON SEP 16 2013
.SHORT TERM...AREAS OF DRIZZLE AND FOG WERE OCCURRING EARLY THIS MORNING IN AND NR
THE FOOTHILLS. THIS ACTIVITY MAY LINGER THRU ABOUT 15Z BEFORE
STARTING TO LIFT.
FOR THIS AFTN THE WK UPPER LEVEL TROUGH WILL FINALLY BEGIN TO EXIT
NERN CO. ALTHOUGH THERE WILL BE DRYING ALOFT SMALL MID LVL COLD
POOL COMBINED WITH LINGERING PRECIPITABLE WATER VALUES AROUND AN
INCH COULD STILL LEAD TO ANOTHER ROUND OF SCT SHOWERS AND TSTMS OVER
THE HIGHER TERRAIN THIS AFTN. A FEW OF THE STORMS COULD PRODUCE
RAINFALL AMOUNTS UP TO AN INCH IN 30 MINUTES. WITH VERY SATURATED
CONDITIONS AND AFTER COORDINATION WITH EOC WILL ISSUE AN FFA FM
18Z- 01Z FOR THE FRONT RANGE FOOTHILLS AND ADJACENT PLAINS WEST OF
I-25 FM THE WY BORDER SOUTH TO THE WRN SUBURBS OF DENVER. AS FOR
AFTN HIGHS READINGS WILL BE WARMER OVER NERN CO WITH HIGHS MAINLY
IN THE LOWER TO MID 70S.
BY TONIGHT TSTM ACTIVITY SHOULD END RATHER QUICKLY BY SUNSET WITH NO
ADDITONAL PCPN OVERNIGHT.
.LONG TERM...WEAK UPPER RIDGING AND ZONAL FLOW ALOFT ON TUESDAY
BECOMES SOUTHWESTERLY TUESDAY NIGHT INTO WEDNESDAY AS AN UPPER
TROUGH MOVES EASTWARD. THE UPPER TROUGH AXIS IS PROGGED OVER
WESTERN COLORADO BY 12Z THURSDAY. THE QG VERTICAL VELOCITY FIELDS
HAVE WEAK DOWNWARD MOTION PROGGED FOR THE CWA TUESDAY...THEN WEAK
UPWARD MOTION IS PROGGED LATE TUESDAY NIGHT THROUGH WEDNESDAY
NIGHT. LOW LEVEL TROUGHING IS PROGGED OVER THE PLAINS TUESDAY INTO
WEDNESDAY...WITH THE NORMAL DIURNAL WIND PATTERNS PARTLY USURPED
BY DOWNSLOPING. BY 12Z THURSDAY MORNING...A COLD FRONT IS EXPECTED
TO BE MOVING ACROSS THE FORECAST AREA. FOR MOISTURE...TUESDAY IS
PRETTY DRY...WITH A SLIGHT INCREASE OF MOISTURE ON WEDNESDAY.
PRECIPITABLE WATER VALUES OVER THE WESTERN PLAINS ARE 0.40 TO 0.70
INCH ON TUESDAY. THEY INCREASE THERE INTO THE 0.70 TO 0.90 INCH
RANGE TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. VALUES FURTHER EAST
ON THE PLAINS ARE A TAD HIGHER. THERE IS LIMITED CAPE PROGGED LATE
DAY TUESDAY...BUT IT INCREASES SOMEWHAT LATE DAY WEDNESDAY. THE
BOUNDARY LAYER DEW POINTS RANGE FROM THE MID 30S F OVER THE
WESTERN FORECAST AREA TO THE LOWER 50S EAST ALL FOUR PERIODS. THE
QPF FIELDS HAD A TAD OF MEASURABLE RAINFALL OVER THE MOUNTAINS
LATE DAY TUESDAY. THERE IS A SLIGHT BIT MORE LATE DAY WEDNESDAY
AND IT ALSO COVERS THE FOOTHILLS. WILL GO MINIMAL POPS LATE DAY
TUESDAY AND WEDNESDAY IN THE MOUNTAINS. FOR TEMPERATURES...
TUESDAY`S HIGHS ARE 3-6 C WARMER THEN TODAY`S. WEDNESDAY`S HIGHS
ARE SIMILAR TO TUESDAY`S. FOR THE LATER DAYS...THURSDAY THROUGH
SUNDAY...MODELS HAVE THE UPPER TROUGH MOVE ACROSS THE CWA ON
THURSDAY. THURSDAY NIGHT INTO SATURDAY MORNING...UPPER RIDGING
MOVES EASTWARD ACROSS THE FORECAST AREA. SOUTHWESTERLY FLOW ALOFT
THEN MOVES IN WITH THE NEXT UPPER TROUGH TO GET INTO COLORADO BY
SUNDAY NIGHT. MOISTURE IS SPARSE UNTIL SUNDAY. TEMPERATURES ARE
AROUND SEASONAL NORMALS THURSDAY AND FRIDAY...THEN ABOVE SATURDAY
AND SUNDAY.
&&
.AVIATION...WK DENVER CYCLONE WAS OVER DENVER EARLY THIS MORNING WITH
SOME AREAS OF FOG AND DRIZZLE. WILL KEEP LIFR CONDITIONS THRU 15Z
WITH IMPROVING CONDITIONS THERAFTER. FOR THIS AFTN THERE WILL BE A
SLIGHT CHC OF TSTMS HOWEVER FOR NOW WILL KEEP ACTIVITY TO THE WEST
AND SW OF DIA AND NOT MENTION IN THE TAF. WINDS THIS AFTN WILL BE
SSE ALTHOUGH THE RAP HAS THEM A BIT MORE ELY. FOR TONIGHT SHOULD
SEE WINDS BECOMING DRAINAGE WITH NO LOW CLOUDS OR FOG EXPECTED
OVERNIGHT.
&&
.HYDROLOGY...AFTER COORDINATION WITH EOC HAVE DECIDED TO ISSUE A FLASH
FLOOD WATCH FOR THE FOOTHILLS AND AREAS WEST OF I-25 FM 18Z-01Z.
THERE IS STILL A POTENTIAL FOR A FEW STORMS TO GENERATE RAINFALL
AMOUNTS UP TO AN INCH IN 30 MINUTES. WITH THE GROUND STILL VERY
SATURATED THIS COULD LEAD TO SOME LOCALIZED FLASH FLOODING IN A
FEW AREAS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FROM NOON MDT TODAY THROUGH EARLY THIS EVENING
FOR COZ035-036-038-039.
&&
$$
SHORT TERM...RPK
LONG TERM....RJK
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1143 PM MDT SUN SEP 15 2013
.UPDATE...
ISSUED AT 1139 PM MDT SUN SEP 15 2013
FLASH FLOOD WATCH HAS BEEN CANCELLED. SHOWER ACTIVITY OVER FREMONT
COUNTY THAT IS EDGING UP INTO TELLER COUNTY IS WEAKENING...AND DO
NOT FEEL POSES ANY THREAT FOR THE REST OF THE NIGHT.
UPDATE ISSUED AT 809 PM MDT SUN SEP 15 2013
QUICK UPDATE TO INCORPORATE LATEST OBS DATA INTO GRIDDED DATABASE.
ALSO...WITH THE AMOUNT OF ONGOING CONVECTION PERSISTING ACROSS THE
CWA...OPTED TO EXTEND THE FLASH FLOOD WATCH FOR EL PASO AND TELLER
COUNTIES UNTIL MIDNIGHT TONIGHT. MOORE
UPDATE ISSUED AT 535 PM MDT SUN SEP 15 2013
UPDATED GRIDS FOR LATEST TRENDS. HEAVIEST RAIN BEGINNING TO WIND
DOWN. HRRR INDICATES SHOWERS DEVELOPING FROM UPPER ARKANSAS SEWD
TO THE RATON WILL SLOWLY MOVE TO THE NE OVER THE NEXT 3-4 HOURS.
THEN...SHOULD WIND DOWN OVERNIGHT WITH JUST SOME ISOLD SHOWERS
AND PC FG TO DEAL WITH MON MORNING. ROSE
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 231 PM MDT SUN SEP 15 2013
...FLASH FLOOD AND HEAVY RAIN THREAT INTO TONIGHT...
BUSY DAY TODAY...AND STILL A WAYS TO GO BEFORE WE ARE OUT OF THE
WOODS FROM THE FLOODING THREAT. HEAVIEST CONVECTION SO FAR HAS BEEN
IN A GROUP OF STRONG STORMS OVER THE ERN AND SRN PORTIONS OF KCOS.
SOME TWO PLUS INCH RAINFALL AMTS THERE...CONTRIBUTING TO URBAN
STREET FLOODING. IT LOOKS LIKE THE STRONGER CONVECTION SHOULD
GRADUALLY BUILD SOUTH OF THE PIKES PK REGION LATER THIS
AFTERNOON...BUT IT WILL BE CLOSE...WITH KCOS AND THE WALDO AREA ON
THE N SIDE OF A NW-SE ORIENTED BOUNDARY THAT RUNS THROUGH SE CO.
THIS IS WHERE THE HEAVIEST CONVECTION IS EXPECTED TO BUILD THROUGH
THE FIRST HALF OF THIS EVENING. WITH SLOW STORM MOVEMENT AND VERY
EFFICIENT PRECIP RATES...WILL CONTINUE TO SEE THE POTENTIAL FOR
LOCALIZED FLASH FLOODING THROUGH THIS TIME.
THE GOOD NEWS IS THAT THINGS SHOULD START TO IMPROVE ON MONDAY.
HEAVIEST SHOWERS SHOULD WIND DOWN BY MIDNIGHT TONIGHT. SOME SCT
SHOWERS EARLY MONDAY...ALONG WITH AREAS OF FG OR BR...THEN SOME
PARTIAL CLEARING BY LATE MORNING INTO THE AFTERNOON. WITH SOME MORE
SUN...COULD SEE ISOLD-SCT SHOWERS OR STORMS REDEVELOP BY
AFTERNOON...BUT SHOULD NOT SEE THE PROBLEMS THAT WE HAVE SEEN TODAY.
TEMPS TOMORROW ALSO STARTING TO REBOUND...WITH HIGHS IN THE MID
70S FOR THE PLAINS. ROSE
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 231 PM MDT SUN SEP 15 2013
...DRYING TREND...
A DRYING TREND WILL BE IN FULL SWING BY TUESDAY...AS A DRIER
WESTERLY FLOW TAKES OVER. THERE WILL STILL BE A COUPLE ROUNDS OF
SHOWERS AND THUNDERSTORMS TO MOVE THROUGH TUESDAY AND WEDNESDAY...BUT
THESE SHOULD MAINLY AFFECT THE MOUNTAINS AND THE CONCERN FOR HEAVY
RAIN WILL BE MUCH LOWER THAN IN RECENT DAYS.
THURSDAY AND FRIDAY ACTUALLY LOOK DRY OVER THE MOUNTAINS AT THIS
POINT...BUT A LOW LEVEL BOUNDARY MAY BACK UP TO THE EASTERN
MOUNTAINS AND PLAINS BRINGING A FEW SHOWERS OR STORMS TO THOSE
AREAS LATE THURSDAY INTO EARLY FRIDAY.
SATURDAY AND SUNDAY...THE FOCUS FOR SHOWERS AND STORMS SHIFTS
BACK TO MAINLY THE MOUNTAINS AGAIN...BUT STILL NOT GREAT COVERAGE
OR RAINFALL AMOUNTS.
THE PRIMARY STORM THREATS TUESDAY THROUGH SUNDAY WILL PROBABLY BE
MORE IN THE LINES OF LIGHTNING AND GUSTY WINDS THAN ANYTHING ELSE.
ALSO...TEMPERATURES WILL BE SHIFTING BACK TO AT OR ABOVE SEASONAL
AVERAGES DURING THE PERIOD. LW
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1139 PM MDT SUN SEP 15 2013
SOME SHOWER ACTIVITY OVER FREMONT COUNTY TONIGHT THAT WILL SLIDE
UP INTO TELLER COUNTY AS IT WEAKENS. SHOWERS OVER OTERO AND LAS
ANIMAS COUNTIES IS DIMINISHING AS WELL...SO EXPECT IMPROVING
CONDITIONS OVERNIGHT FOR MOST AREAS. HOWEVER...LOW CIGS AND SOME
PATCHY FOG IS PROBABLE THROUGH 14Z FOR KPUB AND MORESO KCOS. VFR
CONDITIONS THEN EXPECTED WITH ISOLATED THUNDERSTORM ACTIVITY OVER
THE HIGHER TERRAIN AFTER 19Z.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...MOORE
SHORT TERM...ROSE
LONG TERM...LW
AVIATION...MOORE
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1001 PM EDT TUE SEP 17 2013
.SYNOPSIS...
HIGH PRESSURE WILL BRING DRY WEATHER THIS WEEK WITH MODERATING TEMPS
BEGINNING WEDNESDAY. EXPECT A COLD FRONT TO MOVE THROUGH THE
REGION SAT NIGHT/SUN WITH SOME RAIN SHOWERS. COOLER AND DRIER
WEATHER RETURNS EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
10 PM UPDATE...
MAINLY SKC SKIES AND WEAK MASS FIELDS SUGGEST GOOD RADIATIONAL
COOLING AND INDEED TEMPS ARE BEGINNING TO SHOW RAPID DECLINE.
HOWEVER...DWPTS AFTER THE BREAKDOWN OF THE BL HAVE SINCE RISEN
INTO THE UPPER 30S TO LOW 40S ACROSS MUCH OF SRN NEW ENGLAND.
THEREFORE...IT WILL TAKE MORE TIME FOR RADIATIONAL COOLING AND
MIXING TO ALLOW FOR THE DWPTS TO DIP INTO THE 30S. GIVEN
THIS...STILL HAVE LOW CONFIDENCE FOR WIDESPREAD FROST OUTSIDE OF
THE CURRENT FROST ADVISORY SO THE CURRENT PLACEMENT STANDS. WILL
KEEP AN EYE ON THINGS AS THE PROGRESS THROUGH MIDNIGHT AND
THEREAFTER. ADJUSTED TEMPS/DWPTS TOWARD LATEST MAV AND RAP BASED
LAV DATA.
PREVIOUS DISCUSSION...
TONIGHT...HIGH PRESSURE CONTINUES TO DOMINATE OVER SOUTHERN NEW
ENGLAND. CALMER WINDS TONIGHT WILL ALLOW FOR BETTER RADIATIONAL
COOLING...SO MANY PLACES...PARTICULARLY ACROSS THE INTERIOR...
WILL LIKELY BE A COUPLE OF DEGREES COOLER THAN LAST NIGHT. FROST
ADVISORIES CONTINUE FOR MUCH OF THE NORTHWESTERN ZONES...WITH THE
POTENTIAL FOR THESE TO BE EXTENDED SOUTH AND EAST LATER THIS
AFTERNOON.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
WEDNESDAY...HIGH PRESSURE IS IN CONTROL YET AGAIN RESULTING IN
ANOTHER BEAUTIFUL SEPTEMBER DAY. MOSTLY SUNNY TO SUNNY SKIES
EXPECTED ACROSS THE REGION. WARMING TEMPERATURES ALOFT WILL ALLOW
TEMPERATURES TO REBOUND INTO THE UPPER 60S TO LOWER 70S AFTER A
COOL START.
WEDNESDAY NIGHT...HIGH PRESSURE SITS JUST TO THE SOUTHWEST OF
SOUTHERN NEW ENGLAND ALLOWING WINDS TO SHIFT TO A MORE WESTERLY OR
SOUTHWESTERLY DIRECTION. THIS WILL LEAD TO SLIGHTLY WARMER
TEMPERATURES OVERNIGHT.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
HIGHLIGHTS...
* DRY WEATHER WITH WARMING TEMPS THURSDAY THRU SUNDAY
* COLD FRONT YIELDS A RISK OF RAIN SHOWERS SAT NIGHT/SUN
SYNOPTIC OVERVIEW AND MODEL PREFERENCES...
00Z ECENS AND 12Z GEFS ENSEMBLES IN A GOOD AGREEMENT ON SIMULATING A
FAIRLY HIGH AMPLITUDE NORTHERN STREAM ACROSS THE NORTHERN STATES AND
THEN THEN SHEARING AND DE-AMPLIFYING DOWNSTREAM INTO NORTHEAST. THIS
LIMITS GULF AND ATLANTIC MOISTURE INTERACTION YIELDING VERY LITTLE
IF ANY PWAT ANOMALY ASSOCIATED WITH TROUGH/FRONTAL PASSAGES. HOWEVER
THE OPERATIONAL 12Z GFS AND 12Z ECMWF INDICATING MODEST SYNOPTIC
SCALE LIFT /VIA Q-VECTOR CONVERGENCE/ COMBINED WITH SOME FRONTAL
FORCING WILL YIELD A NARROW BAND OF SHOWERS ALONG AND AHEAD OF THE
FRONT SAT NIGHT AND SUNDAY.
AS FOR POPS...BASICALLY FOLLOWED AN EVEN BLEND OF HPC AND GFS MOS
WHICH YIELDS CHANCE POPS FOCUSED ON SUNDAY. THUS NO CHANGE FROM
PREVIOUS FORECAST WITH DRY WEATHER PREVAILING WITH THE EXCEPTION SAT
NIGHT INTO SUNDAY.
REGARDING TEMPS...MAXS AND MINS WERE DERIVED FROM AN EVEN BLEND OF
HPC/GFS AND ECMWF YIELDING AT OR WARMER THAN NORMAL TEMPS
THU/FRI/SAT AND SUN...THEN TRENDING COOLER MON AND TUE.
DAILY DETAILS...
THURSDAY AND FRIDAY...
SHORT WAVE RIDGING MOVES ACROSS THE REGION ALONG WITH WARMING TEMPS
AS SURFACE HIGH MOVES OFFSHORE. GEFS ENSEMBLES/GFS/ECMWF HAVE +16C
925 TEMPS OVER THE AREA WHICH SHOULD TRANSLATE TO HIGHS IN THE MU70S
AWAY FROM THE COASTLINE. LITTLE WRINKLE IN THE FORECAST FOR FRI AS A
WEAK BACKDOOR COLD FRONT MAY COOL TEMPS DOWN A FEW NOTCHES
ESPECIALLY OVER EASTERN MA AND RI. NEVERTHELESS DRY COLUMN SHOULD
YIELD LOTS OF SUNSHINE AND WEAK PGRAD PROVIDING FAIRLY LIGHT WINDS.
SATURDAY AND SUNDAY...
HEIGHT FALLS BEGIN TO OCCUR OVER THE NORTHEAST AS NEXT NORTHERN
STREAM TROUGH MOVES ACROSS THE GREAT LAKES. LOW LEVEL WARM AIR
ADVECTION INCREASES SAT AHEAD OF THE TROUGH SO EXPECT COOL MARITIME
AIRMASS FROM BACK DOOR FRONT TO ERODE AS BREEZY SSW WINDS DEVELOP
ALONG WITH RISING DEW PTS/HUMIDITY. INCREASING LOW LEVEL WARM AIR
ADVECTION MAY RESULT IN SOME EXTRA CLOUDINESS SAT. HOWEVER EXPECTING
DRY WEATHER TO PREVAIL MUCH IF NOT THE ENTIRE DAY ESPECIALLY ACROSS
RI AND EASTERN MA. LOW RISK OF SHOWERS WESTERN NEW ENGLAND.
ENSEMBLES AND DETERMINISTIC GUIDANCE SUGGEST BEST MOISTURE ADVECTION
AND HIGHEST POPS MOVE ACROSS SOUTHERN NEW ENGLAND SAT NIGHT AND
SUNDAY AS A COLD FRONT TRAVERSES THE AREA. 12Z ECMWF AND 12Z GFS
FAIRLY GENEROUS WITH QPF ACROSS THE AREA SUNDAY. ALTHOUGH SOME
UNCERTAINTY AS TROUGH DEAMPLIFIES AND LIFTS/SHEARS OUT TO THE
NORTHEAST ACROSS ONTARIO AND QUEBEC. NEVERTHELESS NOT EXPECTING A
WASHOUT BUT A 3-6 HR WINDOW OF SHOWERS ARE POSSIBLE.
MON AND TUE...
TROUGH LIFTS OUT WITH RISING HEIGHTS OVER THE NORTHEAST AS SHORT
WAVE RIDGING MOVES ACROSS THE GREAT LAKES. POST FRONTAL AIRMASS
BEHIND EXITING TROUGH SUN IS ONLY SEASONABLY COOL WITH BOTH GEFS AND
ECENS ENSEMBLES HAVING A 1022 MB HIGH ADVECTING INTO THE NORTHEAST
ALONG WITH 850 TEMPS ONLY COOLING TO +8C TO +10C. SO EXPECTING TEMPS
TO SETTLE BACK TO SEASONAL NORMS THIS PERIOD ALONG WITH DRY WEATHER.
SLIGHTLY COOLER ACROSS EASTERN MA GIVEN POSSIBLE STIFF NORTHEAST
WIND OFF THE OCEAN.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
7 PM UPDATE...
NO CHANGES PLANNED AS EARLIER FORECAST MATCHING UP NICELY WITH
CURRENT OBSERVATIONS.
SHORT TERM /THROUGH WEDNESDAY NIGHT/...HIGH CONFIDENCE.
MAINLY VFR THROUGH THE PERIOD. THE EXCEPTION WILL BE FOR PATCHY
GROUND FOG RESULTING IN A FEW HOURS OF LOWER CONDITIONS DURING THE
LATE NIGHT/EARLY MORNING HOURS IN THE TYPICALLY PRONE LOCATIONS. N
TO NE WINDS GUST TO 20-25 KT THIS AFTERNOON ALONG THE SOUTHEAST
NEW ENGLAND COAST. THESE WINDS SHOULD DIMINISH BY LATE THIS
AFTERNOON.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. VFR. AS OF 7 PM LGT/VRB
WIND BEGINNING TO SHIFT TO THE SSW. EXPECT TYPICAL
DIURNAL/NOCTURNAL LIGHT WIND TREND WITH SSW WINDS THIS EVENING
BECOMING NORTHERLY TOWARD SUNRISE.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF. VFR.
OUTLOOK...THURSDAY THROUGH SUNDAY...
THU AND FRI...HIGH CONFIDENCE FOR VFR/DRY WEATHER AND LIGHT WINDS.
SAT...MODERATE CONFIDENCE FOR MARGINAL MVFR/VFR CIGS BUT DRY WEATHER
SHOULD PREVAIL. INCREASING S WINDS.
SUN...MODERATE CONFIDENCE FOR MVFR/VFR WITH SCATTERED SHOWERS.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT TERM /THROUGH WEDNESDAY NIGHT/...HIGH CONFIDENCE.
HIGH PRES BUILDS OVER THE WATERS THROUGH THE PERIOD. WINDS AND
SEAS ARE EXPECTED TO GRADUALLY DIMINISH THROUGH THE AFTERNOON AND
EVENING. ONCE WINDS AND SEAS DROP BELOW SMALL CRAFT THRESHOLDS BY
THIS AFTERNOON AND EVENING...THEY ARE EXPECTED TO REMAIN BELOW SCA
THROUGH WEDNESDAY NIGHT.
OUTLOOK...THURSDAY THROUGH SUNDAY...
NICE BOATING WEATHER WITH HIGH PRES SOUTH OF NEW ENGLAND PROVIDING
DRY WEATHER AND FAIRLY LIGHT WINDS...EXCEPT SAT AS SOUTH WINDS
INCREASE. BY SAT NIGHT/SUN RISK OF SHOWERS WITH APPROACHING COLD
FRONT.
&&
.CLIMATE...
THE FOLLOWING ARE THE RECORD LOWS FOR SEPT 18...
BOS...43 DEGREES 1875
PVD...39 DEGREES 1990
BDL...36 DEGREES 1986
ORH...34 DEGREES 1990
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...FROST ADVISORY FROM 2 AM TO 8 AM EDT WEDNESDAY FOR MAZ002>004-
008>011-026.
NH...FROST ADVISORY FROM 2 AM TO 8 AM EDT WEDNESDAY FOR NHZ011-015.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT WEDNESDAY FOR ANZ254-255.
&&
$$
SYNOPSIS...NOCERA/RLG
NEAR TERM...DOODY/RLG
SHORT TERM...RLG
LONG TERM...NOCERA
AVIATION...NOCERA/RLG
MARINE...NOCERA/RLG
CLIMATE...
AREA FORECAST DISCUSSION
NWS ALBANY NY
1007 AM EDT MON SEP 16 2013
.SYNOPSIS...
.AN UPPER LEVEL DISTURBANCE WILL PRODUCE ISOLATED TO
SCATTERED SHOWERS ACROSS THE REGION THIS AFTERNOON. ANOTHER LARGE
HIGH PRESSURE SYSTEM WILL BUILD IN FROM THE UPPER GREAT LAKES
TONIGHT AND TUESDAY...THEN SETTLE JUST OFF THE EAST COAST DURING THE
MIDDLE AND END OF THE WORK WEEK. THIS HIGH WILL BRING COOL DAYTIME
HIGHS TODAY AND TUESDAY...WITH CHILLY NIGHTS TONIGHT AND TUESDAY
NIGHT. TEMPERATURES WILL BEGIN TO MODERATE ON WEDNESDAY AND REACH
ABOVE NORMAL LEVELS BY THE END OF THE WORK WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1006 AM EDT...THE SFC COLD FRONT HAS MOVED SOUTH OF THE FCST
AREA WITH THE PREFRONTAL SCT SHOWERS. SOME SUBSIDENCE IN THE WAKE
OF THE FRONT HAS ALLOWED THE SKIES TO BECOME PARTLY SUNNY OVER THE
ERN CATSKILLS...CAPITAL REGION...UPPER HUDSON VALLEY...AND SRN VT.
THE VISIBLE SATELLITE PICTURE SHOWS THE CLOUDS FILLING BACK IN
NORTH AND WEST OF ALBANY...AS THE UPPER LEVEL TROUGH AXIS CLOSES
IN FROM THE ERN GREAT LAKES REGION/SE ONTARIO. ISOLD-SCT SHOWERS
WILL BE POSSIBLE THIS AFTERNOON...ESPECIALLY OVER THE HIGHER
TERRAIN. MAX TEMPS WERE RAISED A FEW DEGREES INTO THE MID 60S OVER
THE CNTRL PORTION OF THE FCST AREA DUE TO THE SUNSHINE IN THE LATE
MORNING. THE WINDS WILL CONTINUE TO VEER TO THE WEST TO NORTHWEST
DURING THE AFTERNOON. THE LATEST 3-KM HRRR SHOWS THE SHOWERS/SPRINKLES
DECREASING IN COVERAGE BY THE MID PM. FROST/FREEZE HEADLINES
REMAIN UP OUTSIDE THE CAPITAL DISTRICT...MID HUDSON
VALLEY...S-CNTRL TACONICS AND NW CT FOR TONIGHT...AS THE LARGE SFC
RIDGE BUILDS IN.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
TONIGHT IS FORECAST TO BE DRY WILL CLOUDS DEPARTING EARLY TONIGHT.
WITH A CHILLY AIRMASS BUILDING INTO THE REGION...ALONG WITH WINDS
BECOMING LIGHT AND CLEARING SKIES...EXPECT TEMPS IN MOST AREAS TO
DROP TO BETWEEN THE UPPER 20S AND MID 30S...WITH UPPER 30S TO AROUND
40 FROM THE CAPITAL DISTRICT TO THE MID HUDSON VALLEY AND EASTWARD
INTO LITCHFIELD COUNTY. FOR THE COLDER AREAS HAVE ISSUED FREEZE
WARNING FOR THE WESTERN AND SOUTHERN ADIRONDACKS INCLUDING SOUTHEAST
WARREN COUNTIES...WITH FROST ADVISORIES FOR THE THE MOHAWK AND
SCHOHARIE VALLEYS...THE EASTERN CATSKILLS...WASHINGTON COUNTY...
NORTHERN SARATOGA COUNTY...EASTERN RENSSELAER COUNTY...SOUTHERN
VERMONT AND BERKSHIRE COUNTY.
THE LARGE HIGH PRESSURE SYSTEM WILL SETTLE OVER THE REGION FOR THE
REMAINDER OF THE SHORT TERM PERIOD AS THE CENTER OF THE HIGH ONLY
SLOWLY DRIFTS TO A POSITION JUST OFF THE EAST COAST BY WEDNESDAY.
CLEAR SKIES AND COOL WEATHER WILL PREVAIL THROUGH TUESDAY NIGHT...
WITH A WARM UP STARTING ON WEDNESDAY AS THE WINDS BECOMING SOUTHERLY
AROUND THE HIGH.
HIGHS TUESDAY WILL BE IN THE UPPER 50S TO MID 60S...LOWS TUESDAY
NIGHT IN THE MID 30S TO AROUND 40. HIGHS WEDNESDAY IN THE UPPER 60S
TO LOWER 70S. SOME FROST IS POSSIBLE AGAIN TUESDAY NIGHT...BUT IT
SHOULD BE LIMITED TO THE ADIRONDACKS AND THE GREEN MOUNTAINS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
IT STILL LOOKS AS IF THE VAST MAJORITY OF THE EXTENDED SHOULD BE DRY
WITH SEASONABLE TEMPERATURES. THE ONLY EXCEPTION WOULD BE SATURDAY
WHEN A COLD FRONT IS FORECAST TO MOVE ON THROUGH.
WEDNESDAY NIGHT INTO THURSDAY...HIGH PRESSURE WILL SLOWLY BE
WEAKENING AS IT MOVES OFFSHORE AT THE SURFACE BUT RIDGING ALOFT WILL
IT ALLOW FOR MODERATING TEMPERATURES AND DRY WEATHER DESPITE AN
INCREASE IN MID LEVEL CLOUDS.
LOWS WEDNESDAY NIGHT WILL BE IN THE 40S WITH HIGHS THURSDAY RANGING
FROM THE UPPER 60S NORTHWEST TO MID 70S ALBANY SOUTHWARD.
THIS RIDGE LOOKS TO HOLD THROUGH FRIDAY NIGHT WITH A WEAK SOUTHERLY
FLOW WHICH WILL BOOST H850 TEMPERATURES TO ABOUT +14C LOCALLY.
LOWS THURSDAY AND FRIDAY NIGHT WILL BE RELATIVELY MILD FOR THE TIME
OF YEAR....50S TO AROUND 60...WITH HIGHS WELL INTO THE 70S...UPPER
70S FROM ALBANY SOUTHWARD.
BY SATURDAY...THE AFOREMENTIONED COLD FRONT IS FORECAST TO MOVE
THROUGH. BOTH THE 00Z GFS AND 00Z ECMWF FORECAST THIS FEATURE TO
MOVE THROUGH DURING THE AFTERNOON. HOWEVER...BOTH MODELS DO NOT
INDICATE A WHOLE LOT OF INSTABILITY WITH ITS PASSAGE. FOR
NOW...BASED ON THE TIME OF YEAR AND LACK OF INSTABILITY...HAVE
DECIDED NOT TO MENTION ANY CHANCE OF THUNDER. LATER RUNS MIGHT
INDICATE MORE INSTABILITY. INCLUDE 40 POPS FOR SATURDAY AND 30 POPS
SATURDAY NIGHT.
HIGHS SATURDAY WILL BE A POINT OR TWO LOWER THAN FRIDAY DUE TO
THICKER CLOUD COVER GENERALLY STILL IN THE 70S.
BY SUNDAY...BOTH THE 00Z GFS AND 00Z ECMWF FORECAST THE FRONT TO
MOVE WELL TO OUR EAST. SOMEWHAT COOLER AIR AND DRIER AIR WILL FOLLOW
ALTHOUGH THIS AIR MASS DOES NOT QUITE AS CHILLY AS THE ONE EARLIER
IN THE PERIOD. H850 TEMPERATURES ARE FORECAST TO DROP TO BETWEEN +6C
NORTH AND +9C SOUTH.
LOWS SATURDAY NIGHT AGAIN WILL BE IN THE 50S BUT HIGHS SUNDAY WILL
RANGE FROM AROUND 60 ACROSS THE ADIRONDACK PARK TO AROUND 70 IN THE
HUDSON VALLEY FROM ALBANY SOUTHWARD.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
A COUPLE OF COLD FRONTS WILL CONTINUE TO CROSS THE TAF SITES...ONE
THIS MORNING AND ANOTHER LATER THIS AFTERNOON. THE FIRST HAS ALREADY
PRODUCED A LINE OF LIGHT SHOWERS AT KGFL...NOW WORKING THROUGH
KALB/KPSF AND SOON TO BE KPOU. THUS FAR...MAINLY VFR CONDITIONS HAVE
ENSUED AND IN THE SHORT TERM WE SEE NO REASON FOR THAT TO CHANGE.
HOWEVER...A SECONDARY COLD FRONT...STILL NORTH OF THE NY/CANADIAN
BORDER WILL SWOOP DOWN ACROSS THE AREA MIDDAY INTO THE AFTERNOON. A
FEW LIGHT SHOWERS COULD ACCOMPANY THIS FRONT. UPSTREAM OBSERVATIONS
SUGGEST WE WILL DEAL WITH MVFR CLOUDS AT THE FRONT NEAR FOR A SHORT
TIME THIS AFTERNOON.
LATER THIS EVENING...LOOK FOR THE SKY TO CLEAR.
OVERNIGHT...CROSSOVER TEMPERATURES LOOK TO BE AROUND 30 WITH LOWS
NOT MUCH HIGHER THAN THAT! FOR NOW...INTRODUCE ONLY MVFR FOG AT
KGFL/KPSF AT 06Z...PATCHY FOG BCFG AT KALB AND SINCE THERE MIGHT
ACTUALLY BE A BREEZE ALL NIGHT...NOTHING AT KPOU.
OUTLOOK...
TUESDAY NIGHT THROUGH THURSDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG
WX.
FRIDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
FRIDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
SATURDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
&&
.FIRE WEATHER...
NO FIRE WEATHER PROBLEMS ARE EXPECTED AT THIS TIME.
A COLD FRONT WILL MOVE THROUGH AND EXIT THE REGION THIS MORNING. IT
WILL PRODUCE SOME SHOWERS THAT MAY LINGER INTO THE AFTERNOON.
ANOTHER LARGE HIGH PRESSURE SYSTEM WILL BUILD IN FROM THE UPPER
GREAT LAKES TONIGHT AND TUESDAY...THEN SETTLE JUST OFF THE EAST
COAST DURING THE MIDDLE AND END OF THE WORK WEEK. THIS HIGH WILL
BRING COOL DAYTIME HIGHS TODAY AND TUESDAY...WITH CHILLY NIGHTS
TONIGHT AND TUESDAY NIGHT. TEMPERATURES WILL BEGIN TO MODERATE ON
WEDNESDAY AND REACH ABOVE NORMAL LEVELS BY THE END OF THE WORK WEEK.
RH VALUES WILL ONLY DROP TO BETWEEN 50 AND 60 PERCENT TODAY...THEN
RISE TO BETWEEN 90 AND 100 PERCENT TONIGHT.
SURFACE WINDS WILL BECOME NORTHERLY TODAY AT AROUND 10 MPH...WITH
SOME GUSTS TO 20 MPH POSSIBLE. THE NORTHERLY WINDS WILL DECREASE TO
5 MPH OR LESS TONIGHT.
&&
.HYDROLOGY...
NO HYDROLOGIC PROBLEMS ARE EXPECTED FOR THE NEXT WEEK. THE COLD
FRONT MOVING THROUGH THIS MORNING WILL PRODUCE ONLY LIGHT AMOUNTS OF
RAINFALL...GENERALLY LESS THAN A QUARTER OF AN INCH...WITH NO IMPACT
ON AREA STREAMS AND RIVERS. THE REST OF THE WORKWEEK IS FORECAST TO
BE DRY.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING
OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE
VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON
OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EDT TUESDAY FOR
NYZ038>041-043-047-048-051-054-058-063-084.
FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT TUESDAY FOR
NYZ032-033-042-082-083.
MA...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EDT TUESDAY FOR
MAZ001-025.
VT...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EDT TUESDAY FOR
VTZ013>015.
&&
$$
SYNOPSIS...GJM/WASULA
NEAR TERM...GJM/WASULA
SHORT TERM...GJM
LONG TERM...HWJIV
AVIATION...HWJIV
FIRE WEATHER...GJM
HYDROLOGY...GJM
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
959 AM EDT MON SEP 16 2013
.UPDATE...
SLOWLY WEAKENING SFC HIGH PRESSURE RIDGE WITH AXIS EXTENDING FROM
THE CAROLINAS INTO THE WRN ATLC CONTINUES TO CIRCULATE A LIGHT TO
MODERATE ONSHORE WIND FLOW ACROSS ECFL. WATERVAPOR IMAGERY SHOWS
THE UPPER LEVEL TROUGH EXTENDING FROM THE SERN GOMEX NEWD ACROSS
CTRL FL...BUT GETTING DEFORMED PRETTY BADLY PER 13KM RUC ANLYS
FIELDS. THE RUC ALSO SHOWS STRONGER H25 DIVG HAS SETTLED BACK SWD
AGAIN ACROSS THE SRN THIRD OF FL THE ADJCT STRAITS AND GOMEX. LOCAL
88D MOSAIC SHOWS WIDESPREAD CONVECTION IN THIS VERY MOIST AND DIVGT
AREA. 12Z RAOBS SHOW PWAT VALUES OVER THE CTRL PENINSULA SIMILAR TO
SUN (1.7" - 1.9") WITH A TAD MORE MOISTURE ACROSS SOUTH FL (~2.2").
H50 TEMPS NOT QUITE AS COOL (-7C) OWING TO SOME BUILDING OF THE
MID LEVEL RIDGE OVHD DURG THE LAST H24.
FOR THE REMAINDER OF TODAY...UPPER TROUGH OVHD WILL CONTINUE TO
DEFORM/WEAKEN AS SFC RIDGE TO THE NORTH BREAKS DOWN AHEAD OF AN
APPROACHING COLD FRONT. EXPECT LOCAL PGRAD TO WEAKEN FURTHER WITH
A MAINLY LIGHT ONSHORE FLOW AND SLOWER INLAND PUSH TO ECSB.
EXPECT ANOTHER CONVECTIVELY ACTIVE AFTERNOON...WITH ACTIVE SEA
AND LAKE BREEZE BOUNDARIES ON BOTH SIDES OF THE STATE. CURRENT
GRIDDED/TEXT FCSTS ARE ALREADY ADVERTISING THIS...SO NOSIG CHGS
ARE NEEDED.
&&
&&
.AVIATION (PREV)...EXPECT HIGHER COVERAGE OF LATE MORNING AND
AFTERNOON SCATTERED SHOWERS AND TSRA...ESPECIALLY SOUTH OF A
KMLB-KMCO-KLEE. FOR NOW...HAVE INDICATED VCSH/VCTS IN ALL TAFS.
ISOLD SHRA PSBL ALONG THE COAST FROM KMLB-KSUA TONIGHT WITH VCSH
EXPECTED.
&&
.MARINE...ONSHORE WINDS AROUND 10KT OVER MUCH OF THE MAOR...
HOWEVER STRONGER WINDS (13-17KT) NOTED AT LKWF1/SPGF1 C-MANS...
JUSTIFIES KEEPING WINDS 10-15KT SOUTH OF SEBASTIAN INLET FOR
BOTH THE NEAR SHORE AND OFFSHORE LEGS. SEAS 2-3FT.
&&
FORECASTS/AVIATION...CRISTALDI
IMPACT WX UPDATES/RADAR...SPRATT
&&
.PREV DISCUSSION... /ISSUED 323 AM EDT MON SEP 16 2013/
TONIGHT...LOW LVL ONSHORE FLOW AND DEEP MOISTURE WILL CONTINUE THE
CHANCE FOR ONSHORE MOVING SHOWERS ALONG THE COAST THROUGH THE NIGHT.
EXPECT 20 PCT CHANCE NRN COASTAL AREAS TO 30 PCT S CSTL WHERE
DEEPEST MOISTURE WILL LINGER. LOWS IN THE 70S.
TUE-THU...STRONG ONSHORE FLOW PATTERN FOR THE MIDDLE OF THE WEEK AS
A STRONGER SURFACE HIGH BUILDS OUT OF THE GREAT LAKES ACROSS THE MID
ATLANTIC AND EVENTUALLY OFF THE COAST BY THURSDAY.
DEEPER MOISTURE ASSOCIATED WITH THE TROPICAL WAVE MOVING THROUGH THE
NW CARIBBEAN WILL KEEP THE HIGHEST RAIN CHANCES ACROSS THE TREASURE
COAST...WITH THE BEST RAIN CHANCES ACROSS THE REGION ON TUESDAY AT
40-60 PERCENT BEFORE A SLIGHTLY DRIER AIRMASS FILTERS IN FROM THE
NORTH. HOW MUCH DRIER DIFFERS BETWEEN THE GFS AND ECMWF.
THE RESULTING PRESSURE GRADIENT WILL RESULT IN SEVERAL DAYS OF
BREEZY CONDITIONS...AND A FAST MOVING AND DIFFUSE EAST COAST SEA
BREEZE PUSHING WELL INLAND BY EARLY-MID AFTERNOON. WHILE THIS WILL
SHIFT THE BEST CHANCE FOR CONVECTION TO THE WEST COAST BY EARLY
EVENING...THE SEABREEZE CIRCULATION WILL NOT BE STRONG ENOUGH TO
SHUT OFF THE POSSIBILITY OF ONSHORE MOVING SHOWERS AND STORMS
THROUGH THE DAY.
FRI-MON...ONSHORE FLOW WILL WEAKEN AS THE GRADIENT SLACKENS IN
RESPONSE TO THE HIGH TO THE NORTH WEAKENING AND MOVING FURTHER INTO
THE ATLANTIC. GFS AND ECMWF DIFFER SLIGHTLY AS TO THE DEGREE OF
DRYING IN THE MID LEVELS AND STEERING FLOW...BUT BOTH DO SHOW ENOUGH
TO KEEP POPS AT 20-30 PERCENT FRI AND SAT WITH MUCH WEAKER STEERING.
BY SUNDAY...BOTH MODELS CONTINUE TO SHOW THE DEVELOPMENT OF A WEAK
LOW AROUND THE YUCATAN PENINSULA/SOUTHERN GULF OF MEXICO. THIS
FEATURE WILL GET PICKED UP BY THE NEXT UPPER LEVEL TROUGH PUSHING
OFF THE EAST COAST AND LIFTED OUT TO THE NE ACROSS CUBA/SOUTH
FL/BAHAMAS IN THE MONDAY-TUESDAY TIMEFRAME. REGARDLESS OF HOW THIS
FEATURE DEVELOPS...IT APPEARS MODELS ARE GOING TOWARDS A WETTER
PERIOD SUN-TUES AND HAVE BUMPED UP POPS TO REFLECT THIS.
&&
.MARINE...
EAST WINDS TO 10-15 KNOTS THIS AFTERNOON INTO TONIGHT WITH SEAS 2-3
FT TODAY INCREASING TO 3-4 FT OFFSHORE BY LATE TONIGHT. SCATTERED
SHOWERS AND LIGHTNING STORMS EXPECTED ACROSS THE WATERS INTO TONIGHT.
TUES-FRI...TIGHTENING GRADIENT OVER THE WATERS AS SURFACE HIGH
PUSHES OUT OF GREAT LAKES TOWARDS THE EASTERN SEABOARD THROUGH MID
WEEK. MODERATE EAST-NORTHEAST FLOW AROUND 15KTS EXPECTED
TUES-THURS...WITH OCCASIONAL 15-20KTS POSSIBLE ON TUES. WINDS WILL
WEAKEN SLIGHTLY TO 10-15KTS ON FRI AS THE HIGH MOVES OFF THE COAST
AND WEAKENS.
THE LENGTHENING FETCH AND INCREASING WINDS WILL ELEVATE SEAS TO 4-5
FT BY TUES AFTN...AND UP TO 6 FT OFFSHORE WED THROUGH FRI. BASED ON
THE CURRENT FORECAST...WILL LIKELY NEED A CAUTIONARY STATEMENT (THE
FIRST ONE IN A FEW WEEKS) FOR THIS TIME PERIOD.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 89 75 89 76 / 40 20 40 20
MCO 92 74 91 73 / 50 20 40 20
MLB 89 77 89 77 / 50 30 50 30
VRB 88 75 90 76 / 60 30 50 30
LEE 91 74 91 74 / 40 20 40 20
SFB 91 75 91 74 / 40 20 40 20
ORL 91 75 91 75 / 50 20 40 20
FPR 88 76 89 75 / 60 30 60 30
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MIAMI FL
147 AM EDT MON SEP 16 2013
.AVIATION...
DEEP MOISTURE WILL REMAIN ACROSS SOUTH FLORIDA OVER THE NEXT
COUPLE DAYS. SHOWERS WERE BEGINNING TO REDEVELOP OVER THE ATLANTIC
WATERS TO THE EAST OF KMIA...AND THESE SHOWERS COULD MOVE TOWARDS
THE COAST OVER THE NEXT SEVERAL HOURS. KEPT WITH VCSH FOR
NOW...BUT IT IS POSSIBLE STORMS COULD DEVELOP NEAR THE TAF SITES
BEFORE 12Z. THE DEEP MOISTURE AND LIGHT TO MODERATE EASTERLY FLOW
COMBINED WITH A WEAK SURFACE TROUGH WILL LEAD TO NUMEROUS SHOWERS
AND STORMS ACROSS THE REGION ONCE AGAIN TODAY. SHOWERS AND STORMS
COULD OCCUR AT ANY TIME THROUGHOUT THE DAY...BUT THE MOST LIKELY
PERIOD MAY BE THE LATE MORNING AND EARLY AFTERNOON FOR THE EAST
COAST AND EARLY TO MID AFTERNOON FOR KAPF. SO ADDED TEMPO AND
PROB30 GROUPS TO ACCOUNT FOR THIS AND KEEP CONSISTENT WITH THE
HIGH POPS FORECAST. MVFR/IFR CONDITIONS ARE POSSIBLE IN/NEAR
SHOWERS AND STORMS. AN UPPER LEVEL VORTICITY MAX IS FORECAST TO
MOVE NORTHWARD TOWARDS THE REGION MONDAY NIGHT INTO TUESDAY
MORNING...AND THIS IS FORECAST TO ENHANCE SHOWERS AND STORMS FOR
AT LEAST THE EAST COAST TAF SITES NEAR OR AFTERNOON THE END OF THE
CURRENT TAF PERIOD.
&&
.PREV DISCUSSION... /ISSUED 930 PM EDT SUN SEP 15 2013/
DISCUSSION...
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE
NIGHT. THE HRRR SHOWS A SIGNIFICANT INCREASE IN COVERAGE, WHICH
MAY BE OVERDONE AS IT SHOWS ACTIVITY NOT ONLY DEVELOPING, BUT ALSO
MOVING SOUTH FROM PALM BEACH COUNTY. GIVEN THE GENERAL FLOW TO
WEST AND NORTHWEST, NOT THINKING IT IS TOTALLY ACCURATE. HOWEVER,
WITH SOME ADDITIONAL CONVECTION DEVELOPING, POPS WILL BE LEFT AT
CHC FOR THE COAST AND RAISED TO NEAR CHC FOR THE INTERIOR THROUGH
06Z.
PREV DISCUSSION... /ISSUED 736 PM EDT SUN SEP 15 2013/
AVIATION...
THE EAST COAST TAF SITES WILL SEE EASTERLY WIND FLOW OF 5 TO 10
KNOTS TONIGHT BEFORE INCREASING TO AROUND 10 KNOTS ON MONDAY. THIS
WILL ALLOW FOR SOME SHOWERS AND THUNDERSTORMS TO WORK INTO THE
EAST COAST TAF SITES TONIGHT INTO MONDAY FROM THE ATLANTIC WATERS.
SO WILL CONTINUE WITH THE VCTS FOR THE EAST COAST TAF SITES
TONIGHT INTO MONDAY. HOWEVER...THE START OF THE THREAT OF STORMS
SHOULD BE BETWEEN 3Z AND 4Z FOR KMIA...KOPF...AND KTMB TAF SITES
WHILE REST OF THE EAST COAST TAF SITES WILL SEE THE THUNDERSTORM
THREAT ANYTIME TONIGHT INTO MONDAY.
KAPF TAF SITE WILL ALSO HAVE AN EASTERLY WIND FLOW TONIGHT INTO
MONDAY WITH SPEEDS AT 5 KNOTS OR LESS TONIGHT INCREASING TO AROUND
10 KNOTS BY MONDAY AFTERNOON. KAPF TAF SITE SHOULD REMAIN DRY
TONIGHT BEFORE THE THREAT OF SHOWERS RETURN TO THE TAF SITE BY 13Z
MONDAY AND THUNDERSTORM THREAT BY 17Z MONDAY.
THE CEILING AND VIS WILL REMAIN IN THE VFR CONDITIONS TONIGHT INTO
MONDAY OVER ALL OF THE TAF SITES...AS ANY SHOWERS OR STORMS THAT
DO TAF SITES WILL BE SHORT LIVE LESS THAN 30 MINUTES. WHEN THE
SHOWERS AND THUNDERSTORM DO AFFECT THE TAF SITES...THE VIS AND
CEILING COULD FALL DOWN INTO THE IFR CONDITIONS AND THIS WILL BE
HANDLE BY A SHORT FUSE TEMPO GROUP.
AVIATION...54/BNB
PREV DISCUSSION... /ISSUED 232 PM EDT SUN SEP 15 2013/
SYNOPSIS...
DEEP TROPICAL MOISTURE SPREADING NORTHWESTWARD OVER THE AREA WILL
LEAD TO A GOOD CHANCE FOR SHOWERS AND THUNDERSTORMS OVER THE NEXT
SEVERAL DAYS.
SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
EARLIER CONVECTION IS SPREADING WEST OF THE REGION...AND WITH
LITTLE ADDITIONAL TIME FOR SURFACE HEATING/DESTABILIZATION...RISK
FOR STRONG/SEVERE CONVECTION IS LOW FOR THE REMAINDER OF THE AFTERNOON.
THE NORTH ATLANTIC RIDGE WILL CONTINUE MOVING NORTH AS ANOTHER RIDGE
LOCATED OVER THE GULF STATES WILL CONTINUE MOVING EAST TOWARDS THE
FLORIDA PENINSULA. THESE FEATURES WILL ALLOW FOR THE WIND FLOW TO
PREVAIL FROM THE EAST ACROSS OUR AREA...KEEPING OUR ATMOSPHERE HUMID AND
WARM. WITH THIS...SUMMER-TYPE AFTERNOON CONVECTION IS EXPECTED
THROUGH AT LEAST MID WEEK...WITH HIGHER COVERAGE ACROSS THE INTERIOR
AND WEST.
LONG TERM ...
MODELS SHOW MID LEVEL HIGH PRESSURE OVER THE CENTRAL GULF STATES,
LEADING TO MORE OF A NORTHWEST FLOW ALOFT IN COMBINATION WITH
CONTINUED E/NE LOW LEVEL WINDS. EARLIER RUNS OF THE ECMWF WERE
SHOWING A MID-LEVEL LOW CUTTING OFF OVER THE EASTERN GULF OF
MEXICO, BUT THE LATEST RUN OF THE ECMWF HAS BACKED OFF FROM THAT
SOLUTION AND IS SIMILAR TO THE GFS IN SHOWING A WEAK TROUGH OVER
THE SE GULF AND STRAITS OF FLORIDA. THE NORTHWEST FLOW ALOFT WILL
INTRODUCE SLIGHTLY DRIER AIR WHICH WOULD BRING POPS BACK DOWN TO
THE 30/40 PERCENT RANGE FOR THE LATTER PART OF THE WEEK INTO NEXT
WEEKEND. NOT A DRY FORECAST, BUT PROBABLY NOT AS WET AS THE FIRST
PART OF THE WEEK.
TEMPERATURES THROUGH THE FORECAST PERIOD WILL SHOW LITTLE CHANGE
AS CONTINENTAL AIR REMAINS WELL TO OUR NORTH.
MARINE...
BAND OF STRONG CONVECTION MOVING WEST THROUGH GULF WATERS IS
PROMPTING SPECIAL MARINE WARNINGS FOR WIND GUSTS IN EXCESS OF 40
KTS. THIS FEATURE SHOULD EXIT BY EARLY THIS EVENING...THEN
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS CAN BE EXPECTED
FOR ALL THE WATERS THROUGH AT LEAST MID-WEEK.
AWAY FROM SHOWERS AND THUNDERSTORMS...EAST WINDS OF 10-15 KTS WILL
PREVAIL WITH SEAS LESS THAN 3 FEET.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 89 78 88 76 / 50 40 60 40
FORT LAUDERDALE 88 80 89 78 / 60 40 60 40
MIAMI 89 79 89 78 / 60 40 60 40
NAPLES 93 75 91 76 / 70 40 60 40
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...57/DG
AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
212 PM EDT MON SEP 16 2013
.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFFSHORE AS A COLD FRONT APPROACHES FROM
THE NORTH. THE FRONT WILL CROSS THE AREA TONIGHT AND STALL JUST
SOUTH OF THE REGION ON TUESDAY. THE FRONT WILL REMAIN JUST SOUTH
OF THE AREA THROUGH FRIDAY WITH ANOTHER COLD FRONT CROSSING THE
REGION LATE IN THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AN UPPER LEVEL TROUGH CROSSING THE EASTERN STATES WILL PUSH A COLD
FRONT SOUTHWARD TOWARD THE AREA THIS AFTERNOON. A COLD FRONT
EXTENDED FROM VIRGINA WESTWARD THROUGH TENNESSEE AND MISSOURI EARLY
THIS AFTERNOON.
THE RUC MODEL INDICATING A WEAK SHORT WAVE CROSSING THE MIDLANDS
THIS AFTERNOON. THIS FEATURE WAS HELPING TO IGNITE CONVECTION OVER
THE EASTERN AND SOUTHERN MIDLANDS EARLY THIS AFTERNOON IN A
MODERATELY UNSTABLE AIRMASS. HAVE INCREASED POPS TO LIKELY ACROSS
THE SOUTHEAST...WITH SLIGHT CHANCE POPS FOR THE REMAINDER OF THE
AREA. ALSO NUDGED AFTERNOON HIGHS TO THE UPPER 80S AND LOWER 90S.
THE COLD FRONT WILL MOVE INTO THE AREA TONIGHT BRINGING ANOTHER
CHANCE OF SHOWERS AND THUNDERSTORMS WITH IT. THE BEST CHANCE FOR
PRECIPITATION WILL BE MAINLY THIS EVENING UNTIL AROUND MIDNIGHT.
OVERNIGHT LOWS WILL BE IN THE MIDDLE TO UPPER 60S.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
FRONT WILL BE JUST SOUTH OF THE AREA TUESDAY MORNING THEN SLIDE
INTO SOUTHERN GA AND STALL DURING THE AFTERNOON HOURS. THIS WILL
BRING SLIGHTLY DRIER AIR INTO THE MID LEVELS OVER THE
REGION...HOWEVER EASTERLY FLOW IN THE LOW LEVELS WILL KEEP
MOISTURE OVER THE AREA. THIS SCENARIO WILL REMAIN IN PLACE THROUGH
WEDNESDAY NIGHT AS HIGH PRESSURE CENTERED OVER THE NEW ENGLAND
STATES MOVES EASTWARD. EXPECT A CHANCE OF PRECIPITATION TUESDAY
MAINLY OVER THE SOUTHERN MIDLANDS AND CSRA WITH A MOSTLY DRY
FORECAST FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. A WEAK UPPER-
LEVEL TROUGH MAY TRIGGER A FEW SHOWERS OVER THE CSRA TUESDAY
AFTERNOON. TEMPERATURES THROUGH THE SHORT TERM WILL BE IN THE
LOWER 80S FOR DAYTIME HIGHS WITH UPPER 50S TO LOWER 60S FOR
OVERNIGHT LOWS.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
MODELS HAVE RECENTLY COME INTO BETTER AGREEMENT WITH THE MAIN
DIFFERENCES SURROUNDING A COLD FRONT EXPECTED TO ARRIVE LATE IN
THE WEEKEND. WEAK FRONTAL BOUNDARY WILL REMAIN JUST SOUTH OF THE
FORECAST AREA THURSDAY THEN BEGIN TRACKING NORTHWARD AS DEEPENING
LOW PRESSURE TRACKS ACROSS THE NORTHERN PLAINS AND PUSHES A COLD
FRONT SOUTHWARD INTO THE SOUTHERN PLAINS. BY FRIDAY A WELL
DEFINED COLD FRONT WILL PUSH THROUGH THE MID MS VALLEY. ALTHOUGH
MODELS DIFFER ON TIMING OF COLD FRONT INTO THE MIDLANDS EXPECT
ARRIVAL LATE SUNDAY...WITH MODELS INDICATING POTENTIAL FOR THE
FRONT TO STALL JUST SOUTH OF THE AREA. WITH SOME QUESTION AS TO HOW
FAR SOUTH THE FRONT MAY STALL...WILL KEEP A SMALL CHANCE POP INTO
MONDAY. TEMPERATURES THROUGH THE LONG TERM WILL BE NEAR NORMAL.
&&
.AVIATION /18Z MONDAY THROUGH FRIDAY/...
LINE OF CONVECTION WILL AFFECT OGB THROUGH 20Z...OTHERWISE VFR
CONDITIONS THROUGH THE EARLY EVENING. DOWNSLOPE FLOW WILL INHIBIT
AFTERNOON CONVECTION AT CAE/CUB/AGS/DNL.
A COLD FRONT WILL MOVE ACROSS THE REGION TONIGHT WITH A FEW SHOWERS
AND THUNDERSTORMS 17/00Z-17/06Z. ALSO...LIGHT WINDS AND MOIST AIR
MASS AHEAD OF THE FRONT COULD ALLOW MVFR OR LOWER VSBYS IN FOG TO
DEVELOP AT AGS/OGB OVERNIGHT. INCREASING NORTHEAST WINDS AND DRIER
AIR BEHIND WILL BRING VFR CONDITIONS THROUGH THE END OF THE TAF
PERIOD.
EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS EXPECTED.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1005 AM EDT MON SEP 16 2013
.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFFSHORE THIS MORNING AS A COLD FRONT
APPROACHES FROM THE NORTH. THE FRONT WILL CROSS THE AREA TONIGHT
AND STALL JUST SOUTH OF THE REGION ON TUESDAY. THE FRONT WILL
REMAIN JUST SOUTH OF THE AREA THROUGH FRIDAY WITH ANOTHER COLD
FRONT CROSSING THE REGION LATE IN THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE WILL SLIDE OFFSHORE AND AWAY FROM THE AREA THIS
AFTERNOON AS A COLD FRONT CURRENTLY ACROSS THE CENTRAL APPALACHIANS
MOVES TOWARD THE CAROLINAS.
ISENTROPIC LIFT GRADUALLY DIMINISHING ACROSS THE MIDLANDS LATE THIS
MORNING AS LOW LEVEL FLOW BECOMES MORE WESTERLY. BATCH OF SHOWERS
OVER THE SOUTHEAST MIDLANDS EXPECTED TO MOVE EAST OF THE MIDLANDS
AROUND MIDDAY. 12Z RUC MODEL INDICATING A WEAK SHORT WAVE OVER THE
UPSTATE TO CROSS THE MIDLANDS THROUGH EARLY AFTERNOON. AIRMASS IS
PROGGED TO BECOME MODERATELY UNSTABLE THIS AFTERNOON WITH A SEA-BREEZE
BOUNDARY APPROACHING THE MIDLANDS AFTER 20Z. THIS COULD ALLOW MORE
CONVECTION TO DEVELOP LATER THIS AFTERNOON. WILL KEEP BEST CHANCE OF
CONVECTION OVER THE SOUTHEAST MIDLANDS.
THE COLD FRONT WILL MOVE INTO THE AREA TONIGHT BRINGING ANOTHER
CHANCE OF SHOWERS AND THUNDERSTORMS WITH IT. TEMPERATURES THIS
AFTERNOON WILL BE IN THE UPPER 80S WITH OVERNIGHT LOWS IN THE MIDDLE
TO UPPER 60S.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
FRONT WILL BE JUST SOUTH OF THE AREA TUESDAY MORNING THEN SLIDE
INTO SOUTHERN GA AND STALL DURING THE AFTERNOON HOURS. THIS WILL
BRING SLIGHTLY DRIER AIR INTO THE MID LEVELS OVER THE
REGION...HOWEVER EASTERLY FLOW IN THE LOW LEVELS WILL KEEP
MOISTURE OVER THE AREA. THIS SCENARIO WILL REMAIN IN PLACE THROUGH
WEDNESDAY NIGHT AS HIGH PRESSURE CENTERED OVER THE NEW ENGLAND
STATES MOVES EASTWARD. EXPECT A CHANCE OF SHOWERS TUESDAY MAINLY
OVER THE CENTRAL MIDLANDS AND CSRA WITH A DRY FORECAST FOR TUESDAY
NIGHT THROUGH WEDNESDAY NIGHT. TEMPERATURES THROUGH THE SHORT TERM
WILL BE IN THE LOWER 80S FOR DAYTIME HIGHS WITH UPPER 50S TO LOWER
60S FOR OVERNIGHT LOWS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
MODELS HAVE COME INTO BETTER AGREEMENT OVER THE PAST COUPLE OF
RUNS WITH THE MAIN DIFFERENCES SURROUNDING A COLD FRONT EXPECTED
TO ARRIVE LATE IN THE WEEKEND. WEAK FRONTAL BOUNDARY WILL REMAIN
JUST SOUTH OF THE FORECAST AREA THURSDAY THEN BEGIN TRACKING
NORTHWARD AS DEEPENING LOW PRESSURE TRACKS ACROSS THE NORTHERN
PLAINS AND PUSHES A COLD FRONT SOUTHWARD INTO THE SOUTHERN PLAINS.
BY FRIDAY THE REMAINS OF THE FRONT WILL BE ACROSS THE FORECAST
AREA WITH A WELL DEFINED COLD FRONT PUSHING THROUGH THE MID MS
VALLEY. ALTHOUGH MODELS DIFFER ON TIMING OF COLD FRONT INTO THE
MIDLANDS EXPECT ARRIVAL LATE SUNDAY...WITH MODELS INDICATING
POTENTIAL FOR THE FRONT TO STALL JUST SOUTH OF THE AREA.
TEMPERATURES THROUGH THE LONG TERM WILL BE NEAR NORMAL.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
PATCH OF IFR CLOUDS AFFECTING AGS/DNL EXPECTED TO LIFT TO VFR BY
16Z. VFR TO CONTINUE AT CAE/CUB/OGB FOR THE AFTERNOON WITH SCT/BKN
CLOUDS ABOVE 3000 FEET. LOW CONFIDENCE OF CONVECTION ASSOCIATED
WITH THE LATE AFTERNOON SEA-BREEZE BOUNDARY WILL AFFECT THE TAF
SITES...SO WILL NOT INCLUDE CONVECTION IN TAFS.
A COLD FRONT WILL MOVE ACROSS THE REGION TONIGHT WITH A FEW
SHOWERS AND THUNDERSTORMS...CONFIDENCE LOW ON TIMING BUT A PERIOD
OF MVFR OR LOWER CONDITIONS IS POSSIBLE AFTER 00Z.
EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS EXPECTED.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1250 PM CDT MON SEP 16 2013
.DISCUSSION...
1050 AM CDT
FOR MORNING UPDATE...
MINOR CHANGES TO GOING FORECAST TO REMOVE MENTION OF LAKE EFFECT
PRECIP THIS MORNING...AND TO TWEAK HOURLY TEMPS AND CLOUD COVER.
SURFACE HIGH PRESSURE OVER THE NORTHERN GREAT LAKES REGION WILL
DRIFT SOUTHEAST THROUGH TONIGHT...IN THE WAKE OF MID-LEVEL SHORT
WAVE PROPAGATING THROUGH THE EASTERN GREAT LAKES AND UPPER OHIO
VALLEY. 12Z RAOB ANALYSIS INDICATES SUBSTANTIAL DRY AIR IN THE
MID/UPPER LEVELS ACROSS THE REGION...WHILE LOW LEVEL MOISTURE WAS
MORE ABUNDANT BENEATH 850MB...WITH CONSIDERABLE CLOUD COVER NOTED
IN SATELLITE IMAGERY OVER LOWER MICHIGAN/INDIANA AND CENTRAL IL.
SUBSIDENCE/RISING HEIGHTS IN THE WAKE OF THE EASTERN GREAT LAKES
SHORT WAVE IS DEPICTED IN FORECAST SOUNDINGS THROUGH GRADUALLY
LOWERING INVERSION...WHICH SHOULD CONTINUE TO THIN/DECREASE CLOUD
COVER ACROSS THE REGION. GOES VISIBLE IMAGERY ALREADY INDICATES
STRATOCUMULUS IS FAIRLY SHALLOW...WITH MODIFIED SOUNDINGS OVER THE
WATER NOT PARTICULARLY FAVORABLE FOR PRECIPITATION WITH STRONG
INVERSION AROUND 3500 FT AGL. EXPECTATION IS THAT STRATOCU WILL
CONTINUE TO THIN OVER THE LAKE AND DOWNSTREAM ACROSS CHICAGO METRO
AREA...THOUGH SOME FLAT CU/STRATOCU DEVELOPMENT WILL OCCUR OVER
LAND AREAS AS TEMPS RISE. THICKEST CLOUD COVER OVER LOWER MICHIGAN
AND NORTHWEST INDIANA WILL BE A LITTLE SLOWER TO THIN/ERODE...BUT
SHOULD ALSO SEE A GRADUAL DOWNWARD TREND IN THICKNESS/COVERAGE.
TEMPS WILL REMAIN A LITTLE COOL EVEN IN SUNNIER AREAS...WITH LOW
LEVEL THERMAL ANALYSIS SUPPORTING TEMPS FROM UPPER 60S/AROUND 70
WELL WEST/SOUTH...AND LOW-MID 60S CLOSER TO THE LAKE WHERE ONSHORE
WINDS WILL KEEP THINGS A BIT COOLER.
RATZER
//PREV DISCUSSION...
307 AM CDT
THE PRIMARY FOCUS OF THE FORECAST WAS ON TIMING CLOUD DISSIPATION
TODAY AND THEN THUNDER CHANCES AND DEGREE OF WARM-UP DURING THE
TUE NIGHT-FRI TIME FRAME.
SYNOPSIS...A GENERAL LONG WAVE TROUGH CONTINUES OVER EASTERN
NORTH AMERICA WITH A RE-ESTABLISHING MID-LEVEL WAVE HAVING
PASSED THROUGH THE GREAT LAKES LAST NIGHT. DESPITE THE SURFACE
WIND SHIFT TO NORTHERLY HAVING HAPPENED LAST EVE...THE TRUE LOW-
LEVEL COLD AIR ADVECTION IS ACTUALLY UNFOLDING EARLY THIS MORNING
ACROSS THE REGION...WITH SEVERAL SITES ESPECIALLY NEAR THE LAKE
GUSTING TO 25 MPH FROM THE NORTHEAST. SATELLITE IR AND 11-3.9
MICRON CHANNELS INDICATE LAKE EFFECT STRUCTURE TO THE CLOUDS FROM
MID-LAKE SSW INTO ADJACENT LAKE COUNTIES OF THE FORECAST AREA.
SCATTERED LIGHT SHOWERS/SPRINKLES HAVE BEEN SEEN ON TDWRS WITHIN
THIS. ELSEWHERE...AREAS OF COLD AIR ADVECTION STRATUS/STRATOCU ARE
NOTED OVER THE REGION. THE SURFACE HIGH IS CENTERED OVER NORTHERN
WI AND THE ARROWHEAD OF MN...WHERE SCATTERED SUB-FREEZING
TEMPERATURES ARE SEEN THIS MORNING.
TODAY...THE SURFACE HIGH WILL BASICALLY MOVE DUE EAST TODAY WITH
A PRESSURE GRADIENT HOLDING ITS OWN OVER THE FORECAST AREA
YIELDING NOT MUCH CHANGE IN WIND ORIENTATION OR SPEED. THIS SHOULD
CONTINUE HIGH WAVES ALONG IL SHORES AND KEEP LAKESIDE TEMPS IN THE
MID 60S OR SO BASED ON OBSERVED AND ESTIMATED WATER TEMPERATURES.
A SCATTERING OF THE SYNOPTIC CLOUDS IS EXPECTED BY LATE MORNING
INTO AFTERNOON...WHILE THE PLUME OF LAKE EFFECT CLOUDS IS LIKELY
TO KEEP SOME PARTS OF THE CHICAGO METRO CLOUDY INTO EARLY
AFTERNOON. THE VARIOUS WRF COLUMN CONDENSATE FORECASTS INDICATE
THIS CHANNEL OF CLOUDS SHIFTING WEST SOME BUT MAINLY HOLDING
TOGETHER THROUGH THE MORNING WHICH SEEM REASONABLE PER FORECAST
SOUNDINGS. AN AMDAR SOUNDING BACK FROM 05Z HAD AN EQUILIBRIUM LEVEL
AROUND 6000 FT AND NOT SEEING MUCH CHANGE AT ALL IN THAT THROUGH
THIS MORNING. SOME LIGHT LAKE EFFECT SHOWERS OR SPRINKLES WILL
PROBABLY HANG IN THERE THROUGH THE MORNING...MAINLY IN LAKE
IL...COOK...AND DUPAGE COUNTIES. CONSIDERING LOCAL CLIMATOLOGY FOR
THE 850MB AND 925MB TEMPERATURES AND THE ANTICIPATED INCREASE IN
SUN BY AFTERNOON...MID TO UPPER 60S IN CHICAGO AND AROUND 70
ELSEWHERE ARE EXPECTED FOR HIGHS.
TUESDAY NIGHT-THURSDAY...AFTER QUIET WEATHER INTO TUESDAY...UPPER
HEIGHTS THEN FURTHER BUILD IN THIS PERIOD AS A RIDGE OVER THE
PLAINS SHIFTS EAST. A LOOSELY DEFINED UPPER LOW OVER EASTERN CO
THIS MORNING /PARTIAL REMNANTS OF THE SIGNIFICANT ONE THAT PRODUCED
RECORD CO FLOODING LAST WEEK/...IS FORECAST TO MOVE ENE AS A SHORT
WAVE UNDER THIS RIDGE. THIS WILL LINE UP WITH SOME BETTER ELEVATED
WARM AIR ADVECTION AND MOIST RETURN LATER TUESDAY NIGHT INTO
WEDNESDAY. GUIDANCE STILL HAS SOME NOTABLE DISCREPANCIES IN
EVOLUTION OF ANY CONVECTION TUE NIGHT INTO WED MORNING...BUT
THICKNESSES AND MOISTURE TRANSPORT FIELDS WOULD POTENTIALLY
SUPPORT FADING CONVECTION MOVING EAST TO SOUTHEAST INTO THE
FORECAST AREA IF SOME CAN INITIALIZE ON THE LLJ TO THE WEST. AFTER
THAT...ANY UPPER FOCUS CONTINUES TO LOOK ILL-DEFINED AS THE
FORECAST AREA LOOKS TO BE IN A WARM SECTOR BY THURSDAY. WHILE
MODELS ADVERTISE QPF WEDNESDAY AFTERNOON-THURSDAY AND CANNOT RULE
OUT SOME SCATTERED CONVECTION...IT WOULD SEEM THEY REMAIN OVERDONE
AND HAVE GONE BELOW A GUIDANCE BLENDED POP. FOR TEMPS...WEDNESDAY
IS A CHALLENGE BASED ON POTENTIAL PRECIP...AND HAVE NOT SWAYED
MUCH FROM THE GOING FORECAST. THE WARMEST READINGS LOOK TO BE ON
THURSDAY WITH MODEST CONFIDENCE OF 80 PLUS OVER MUCH OF THE CWA
GIVEN SUPPORT OF LOCAL CLIMATOLOGY AND BIAS-CORRECTED
GUIDANCE...WHICH HAS WORKED WELL IN THE WARM STRETCHES DURING THE
PAST MONTH.
THURSDAY NIGHT-FRIDAY...LONG RANGE GUIDANCE IS IN GOOD AGREEMENT
OF AN UPPER WAVE MOVING ALONG THE CANADIAN BORDER IN THIS PERIOD
WITH AN ASSOCIATED SURFACE COLD FRONT MOVING THROUGH THE FORECAST
AREA. FORCING FOR CONVECTIVE PRECIP IS THERE ON ALL GUIDANCE BUT
CAN LIKELY EXPECT TO SEE SOME TIMING SHIFTS. HAVE LIKELY POPS
AREAWIDE THU NIGHT FOR NOW. GFS PWAT AND MOISTURE TRANSPORT
PROJECTIONS DO INDICATE THAT SOME OF THE DEEP MOISTURE FROM TROPICAL
STORM INGRID GETS WRAPPED INTO PART OF THE SYNOPTIC WARM
SECTOR...THOUGH IT DOES NOT APPEAR TO TRAVERSE THIS FAR NORTH.
SOMETHING CERTAINLY TO KEEP AN EYE ON THOUGH FOR MORE EFFICIENT
RAINFALL PRODUCTION.
BEYOND...WITH THE JET STREAM TO THE NORTH AND THE PATTERN
REMAINING PROGRESSIVE...TEMPERATURES LOOK TO BE AROUND NORMAL OR
JUST A TAD BELOW NEXT WEEKEND. ALSO GIVEN THE CURRENT TIMING OF
SYSTEMS IT WOULD LOOK TO BE DRY AS WELL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* POSSIBLE SPORADIC VFR CEILINGS OVER THE NEXT 1-2 HOURS.
RODRIGUEZ
//DISCUSSION...UPDATED 18Z...
WITH HIGH PRESSURE BUILDING ACROSS THE REGION...QUIET CONDITIONS
ONGOING AT THE TERMINALS. LATEST SATELLITE IMAGERY DEPICTING CLOUD
COVER DECREASING IN COVERAGE EARLY THIS AFTERNOON...AND EXPECT
THIS TREND TO CONTINUE THROUGH THE REMAINDER OF THE AFTERNOON.
ALTHOUGH VFR CEILINGS WILL BE POSSIBLE EARLY...EXPECT THE
PREVAILING CONDITION TO BE MORE SCT AND HAVE THE TAFS REPRESENTING
THESE CONDITIONS. HIGH LEVEL CLOUD COVER WILL THEN BE THE ONLY
CLOUDS EXPECTED THROUGH THE REST OF THE FORECAST PERIOD. NORTHEAST
WINDS GUSTING TO THE UPPER TEENS WILL PREVAIL THIS
AFTERNOON...THEN DIMINISH WHILE SHIFTING MORE EAST SOUTHEAST
TONIGHT INTO EARLY TUESDAY MORNING.
RODRIGUEZ
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE WITH VFR CONDITIONS.
* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT...VFR. CHANCE SHRA LATE.
WEDNESDAY AND THURSDAY...CHANCE SHRA/TSRA...OTHERWISE VFR.
FRIDAY...CHANCE SHRA EARLY. COLD FRONTAL PASSAGE EARLY WITH SHARP
WIND DIRECTION SHIFT FROM SLY TO NWLY.
FRIDAY NIGHT THROUGH SUNDAY...VFR. WX NIL.
KREIN
&&
.MARINE...
307 AM CDT
STRONG HIGH PRESSURE CONTINUES TO SPREAD INTO THE UPPER GREAT
LAKES AS THE COLD FRONT PUSHES INTO THE OHIO VALLEY. A SECONDARY
SURGE OF COOLER AIR SPREADING DOWN THE LAKE HAS HELPED INCREASE
WINDS TO AROUND 30KT THROUGH THE EARLY MORNING HOURS. AS THE THE
CENTER OF THE HIGH SLIDES TO THE SOUTHEAST INTO THE EASTERN GREAT
LAKES MONDAY NIGHT...THE GRADIENT WILL RELAX...ALLOWING WIND
SPEEDS TO DECREASE AND DIRECTION TO VEER FROM GENERALLY NORTHERLY
TODAY TO SOUTHERLY BY TUESDAY MORNING. THE SOUTH WINDS WILL
PERSIST THROUGH THURSDAY AND THEN VEER MORE SOUTHWESTERLY BY
FRIDAY AS DEEP LOW PRESSURE MOVES INTO SOUTH CENTRAL CANADA AND A
STRONG COLD FRONT APPROACHES THE UPPER MISSISSIPPI VALLEY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014 UNTIL 4 PM TUESDAY.
IN...BEACH HAZARDS STATEMENT...INZ001 UNTIL 4 PM TUESDAY.
BEACH HAZARDS STATEMENT...INZ002 UNTIL 10 PM MONDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 4 PM
TUESDAY.
SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 11 PM MONDAY.
&&
$$
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Area Forecast Discussion
National Weather Service Lincoln IL
1226 PM CDT Mon Sep 16 2013
.DISCUSSION...
ISSUED 1000 AM CDT Mon Sep 16 2013
Stratocumulus deck continues to thin out over a good part of
central Illinois this morning, with the northern edge basically
along I-74 from Galesburg to near Bloomington. However, some
higher clouds evident in satellite imagery spreading eastward over
the state. Cu-rule off the RAP model continues to show some
erosion of the lower cloud deck as drier air advects in from the
northeast.
Have sent some updated grids to bump up the winds and adjust the
dew points a bit. Temperatures still look good. The changes do not
require a change to the zone forecasts at this point.
Geelhart
&&
.AVIATION...
ISSUED 1225 PM CDT Mon Sep 16 2013
MVFR ceilings around 2500 feet still trying to fully break apart
from KSPI eastward to KCMI, but this may take a couple more hours
as areas near KPIA/KBMI are currently on the verge of losing all
of the lower clouds. Still will see high clouds streaming through
once the lower clouds scatter out. Gusty northeast winds will
begin to settle down in a few hours, then gradually swing to the
southeast late tonight and early Tuesday as high pressure pushes
further east across the Great Lakes. On Tuesday, concern shifts
toward an incoming upper disturbance from the west which will
bring some showers. However, latest model guidance pretty much
keeps any rain threat to the west of the TAF sites most of the
day. VFR ceilings will gradually lower ahead of this system, but
still remain well above 10KFT through 18Z.
Geelhart
&&
.PREV DISCUSSION...
ISSUED 257 AM CDT Mon Sep 16 2013
Cold front has moved through the FA this morning...stretching
along the Ohio River Valley while cooler air moves into place for
much of the Midwest. Northeasterly winds have settled in as a
surface high pressure, centered in northern MN, builds back into
the Midwest. Persistent upper level ridging over the Rockies and
the high plains providing a source of warming later in the
forecast...but for the next couple of days the temperatures are
rather cool. Into the remainder of the week, the forecast becomes
problematic almost immediately with a return of pops and a lack of
consistency in operational models. Low chance pops dominate
between a shortwave moving through Tuesday night/Wednesday and an
actual front on Thu night/Friday. On the other side of Friday
night...next weekend dries back out. Though breaks in the rain is
expected between Wednesday afternoon and Thursday night, models are
filling the gap with low pops.
SHORT TERM...Today and tomorrow...
Slow drying out behind the boundary with cooler temps expected
today. Clearing of clouds slowly as high pressure builds into the
region. Some clearing to the NW will work into the region...though
plenty of remnant clouds will move in from the SW and convection
behind the front in MO. Variable clouds through the day will
dissolve into the evening hours, clearing out and assisting
efficient radiational cooling and a temp drop into the 50s.
Tomorrow the winds get a small southerly component and the general
moderation of the air mass begins and temperatures start to climb a
couple degrees. That being said, clouds should be on the increase
so cooling tomorrow night should be impeded by the increasing
cloud cover. Pops return to forecast tomorrow afternoon in the
east and into the overnight, although concern for speed of onset of
QPF in general with the wave moving much faster in 00Z runs.
LONG TERM...Wednesday through Sunday...
Temperatures moderating somewhat by Wednesday due to a eastward
trending of the western mid level thermal ridge. Expect some
variability in the guidance as the portrayal of the next system
becomes clearer, right now being torn between the warmth under the
ridge and the threat of advancing rain. Pops move in Tues night
and continue through Friday with a lack of consistency for GFS and
ECMWF, as a result muddying the AllBlend. In addition, models
attempting a slow progression of initial wave and create an
interaction between remnant energy aloft and developing boundary
as another upper trof pushes into the region. Both ECMWF and GFS
fill the gap with pops across the board, so the AllBlend follows
suit. GFS and ECMWF are alternating being the most aggressive with
the strength and depth of the wave...and the QPF as well. For now,
the forecast remains rather diffuse and generous with the pops.
Best chances for precipitation beyond Wednesday looks to be in the
Thursday night/Friday time frame, associated with a cold front as
an aggressive trof digs in over the upper Midwest.
HJS
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1052 AM CDT MON SEP 16 2013
.DISCUSSION...
1050 AM CDT
FOR MORNING UPDATE...
MINOR CHANGES TO GOING FORECAST TO REMOVE MENTION OF LAKE EFFECT
PRECIP THIS MORNING...AND TO TWEAK HOURLY TEMPS AND CLOUD COVER.
SURFACE HIGH PRESSURE OVER THE NORTHERN GREAT LAKES REGION WILL
DRIFT SOUTHEAST THROUGH TONIGHT...IN THE WAKE OF MID-LEVEL SHORT
WAVE PROPAGATING THROUGH THE EASTERN GREAT LAKES AND UPPER OHIO
VALLEY. 12Z RAOB ANALYSIS INDICATES SUBSTANTIAL DRY AIR IN THE
MID/UPPER LEVELS ACROSS THE REGION...WHILE LOW LEVEL MOISTURE WAS
MORE ABUNDANT BENEATH 850MB...WITH CONSIDERABLE CLOUD COVER NOTED
IN SATELLITE IMAGERY OVER LOWER MICHIGAN/INDIANA AND CENTRAL IL.
SUBSIDENCE/RISING HEIGHTS IN THE WAKE OF THE EASTERN GREAT LAKES
SHORT WAVE IS DEPICTED IN FORECAST SOUNDINGS THROUGH GRADUALLY
LOWERING INVERSION...WHICH SHOULD CONTINUE TO THIN/DECREASE CLOUD
COVER ACROSS THE REGION. GOES VISIBLE IMAGERY ALREADY INDICATES
STRATOCUMULUS IS FAIRLY SHALLOW...WITH MODIFIED SOUNDINGS OVER THE
WATER NOT PARTICULARLY FAVORABLE FOR PRECIPITATION WITH STRONG
INVERSION AROUND 3500 FT AGL. EXPECTATION IS THAT STRATOCU WILL
CONTINUE TO THIN OVER THE LAKE AND DOWNSTREAM ACROSS CHICAGO METRO
AREA...THOUGH SOME FLAT CU/STRATOCU DEVELOPMENT WILL OCCUR OVER
LAND AREAS AS TEMPS RISE. THICKEST CLOUD COVER OVER LOWER MICHIGAN
AND NORTHWEST INDIANA WILL BE A LITTLE SLOWER TO THIN/ERODE...BUT
SHOULD ALSO SEE A GRADUAL DOWNWARD TREND IN THICKNESS/COVERAGE.
TEMPS WILL REMAIN A LITTLE COOL EVEN IN SUNNIER AREAS...WITH LOW
LEVEL THERMAL ANALYSIS SUPPORTING TEMPS FROM UPPER 60S/AROUND 70
WELL WEST/SOUTH...AND LOW-MID 60S CLOSER TO THE LAKE WHERE ONSHORE
WINDS WILL KEEP THINGS A BIT COOLER.
RATZER
&&
.PREV DISCUSSION...
307 AM CDT
THE PRIMARY FOCUS OF THE FORECAST WAS ON TIMING CLOUD DISSIPATION
TODAY AND THEN THUNDER CHANCES AND DEGREE OF WARM-UP DURING THE
TUE NIGHT-FRI TIME FRAME.
SYNOPSIS...A GENERAL LONG WAVE TROUGH CONTINUES OVER EASTERN
NORTH AMERICA WITH A RE-ESTABLISHING MID-LEVEL WAVE HAVING
PASSED THROUGH THE GREAT LAKES LAST NIGHT. DESPITE THE SURFACE
WIND SHIFT TO NORTHERLY HAVING HAPPENED LAST EVE...THE TRUE LOW-
LEVEL COLD AIR ADVECTION IS ACTUALLY UNFOLDING EARLY THIS MORNING
ACROSS THE REGION...WITH SEVERAL SITES ESPECIALLY NEAR THE LAKE
GUSTING TO 25 MPH FROM THE NORTHEAST. SATELLITE IR AND 11-3.9
MICRON CHANNELS INDICATE LAKE EFFECT STRUCTURE TO THE CLOUDS FROM
MID-LAKE SSW INTO ADJACENT LAKE COUNTIES OF THE FORECAST AREA.
SCATTERED LIGHT SHOWERS/SPRINKLES HAVE BEEN SEEN ON TDWRS WITHIN
THIS. ELSEWHERE...AREAS OF COLD AIR ADVECTION STRATUS/STRATOCU ARE
NOTED OVER THE REGION. THE SURFACE HIGH IS CENTERED OVER NORTHERN
WI AND THE ARROWHEAD OF MN...WHERE SCATTERED SUB-FREEZING
TEMPERATURES ARE SEEN THIS MORNING.
TODAY...THE SURFACE HIGH WILL BASICALLY MOVE DUE EAST TODAY WITH
A PRESSURE GRADIENT HOLDING ITS OWN OVER THE FORECAST AREA
YIELDING NOT MUCH CHANGE IN WIND ORIENTATION OR SPEED. THIS SHOULD
CONTINUE HIGH WAVES ALONG IL SHORES AND KEEP LAKESIDE TEMPS IN THE
MID 60S OR SO BASED ON OBSERVED AND ESTIMATED WATER TEMPERATURES.
A SCATTERING OF THE SYNOPTIC CLOUDS IS EXPECTED BY LATE MORNING
INTO AFTERNOON...WHILE THE PLUME OF LAKE EFFECT CLOUDS IS LIKELY
TO KEEP SOME PARTS OF THE CHICAGO METRO CLOUDY INTO EARLY
AFTERNOON. THE VARIOUS WRF COLUMN CONDENSATE FORECASTS INDICATE
THIS CHANNEL OF CLOUDS SHIFTING WEST SOME BUT MAINLY HOLDING
TOGETHER THROUGH THE MORNING WHICH SEEM REASONABLE PER FORECAST
SOUNDINGS. AN AMDAR SOUNDING BACK FROM 05Z HAD AN EQUILIBRIUM LEVEL
AROUND 6000 FT AND NOT SEEING MUCH CHANGE AT ALL IN THAT THROUGH
THIS MORNING. SOME LIGHT LAKE EFFECT SHOWERS OR SPRINKLES WILL
PROBABLY HANG IN THERE THROUGH THE MORNING...MAINLY IN LAKE
IL...COOK...AND DUPAGE COUNTIES. CONSIDERING LOCAL CLIMATOLOGY FOR
THE 850MB AND 925MB TEMPERATURES AND THE ANTICIPATED INCREASE IN
SUN BY AFTERNOON...MID TO UPPER 60S IN CHICAGO AND AROUND 70
ELSEWHERE ARE EXPECTED FOR HIGHS.
TUESDAY NIGHT-THURSDAY...AFTER QUIET WEATHER INTO TUESDAY...UPPER
HEIGHTS THEN FURTHER BUILD IN THIS PERIOD AS A RIDGE OVER THE
PLAINS SHIFTS EAST. A LOOSELY DEFINED UPPER LOW OVER EASTERN CO
THIS MORNING /PARTIAL REMNANTS OF THE SIGNIFICANT ONE THAT PRODUCED
RECORD CO FLOODING LAST WEEK/...IS FORECAST TO MOVE ENE AS A SHORT
WAVE UNDER THIS RIDGE. THIS WILL LINE UP WITH SOME BETTER ELEVATED
WARM AIR ADVECTION AND MOIST RETURN LATER TUESDAY NIGHT INTO
WEDNESDAY. GUIDANCE STILL HAS SOME NOTABLE DISCREPANCIES IN
EVOLUTION OF ANY CONVECTION TUE NIGHT INTO WED MORNING...BUT
THICKNESSES AND MOISTURE TRANSPORT FIELDS WOULD POTENTIALLY
SUPPORT FADING CONVECTION MOVING EAST TO SOUTHEAST INTO THE
FORECAST AREA IF SOME CAN INITIALIZE ON THE LLJ TO THE WEST. AFTER
THAT...ANY UPPER FOCUS CONTINUES TO LOOK ILL-DEFINED AS THE
FORECAST AREA LOOKS TO BE IN A WARM SECTOR BY THURSDAY. WHILE
MODELS ADVERTISE QPF WEDNESDAY AFTERNOON-THURSDAY AND CANNOT RULE
OUT SOME SCATTERED CONVECTION...IT WOULD SEEM THEY REMAIN OVERDONE
AND HAVE GONE BELOW A GUIDANCE BLENDED POP. FOR TEMPS...WEDNESDAY
IS A CHALLENGE BASED ON POTENTIAL PRECIP...AND HAVE NOT SWAYED
MUCH FROM THE GOING FORECAST. THE WARMEST READINGS LOOK TO BE ON
THURSDAY WITH MODEST CONFIDENCE OF 80 PLUS OVER MUCH OF THE CWA
GIVEN SUPPORT OF LOCAL CLIMATOLOGY AND BIAS-CORRECTED
GUIDANCE...WHICH HAS WORKED WELL IN THE WARM STRETCHES DURING THE
PAST MONTH.
THURSDAY NIGHT-FRIDAY...LONG RANGE GUIDANCE IS IN GOOD AGREEMENT
OF AN UPPER WAVE MOVING ALONG THE CANADIAN BORDER IN THIS PERIOD
WITH AN ASSOCIATED SURFACE COLD FRONT MOVING THROUGH THE FORECAST
AREA. FORCING FOR CONVECTIVE PRECIP IS THERE ON ALL GUIDANCE BUT
CAN LIKELY EXPECT TO SEE SOME TIMING SHIFTS. HAVE LIKELY POPS
AREAWIDE THU NIGHT FOR NOW. GFS PWAT AND MOISTURE TRANSPORT
PROJECTIONS DO INDICATE THAT SOME OF THE DEEP MOISTURE FROM TROPICAL
STORM INGRID GETS WRAPPED INTO PART OF THE SYNOPTIC WARM
SECTOR...THOUGH IT DOES NOT APPEAR TO TRAVERSE THIS FAR NORTH.
SOMETHING CERTAINLY TO KEEP AN EYE ON THOUGH FOR MORE EFFICIENT
RAINFALL PRODUCTION.
BEYOND...WITH THE JET STREAM TO THE NORTH AND THE PATTERN
REMAINING PROGRESSIVE...TEMPERATURES LOOK TO BE AROUND NORMAL OR
JUST A TAD BELOW NEXT WEEKEND. ALSO GIVEN THE CURRENT TIMING OF
SYSTEMS IT WOULD LOOK TO BE DRY AS WELL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* HIGH END MVFR CIGS POSSIBLE THROUGH LATE MORNING.
* WIND DIRECTION VARYING FROM NNW TO NNE OVER THE NEXT 1-2 HOURS
BEFORE A MORE PREVAILING NE DIRECTION SETS IN FOR THE REMAINDER
OF THE DAY...WITH GUSTS TO THE UPPER TEENS.
RODRIGUEZ
//DISCUSSION...UPDATED 12Z...
A SECONDARY SURGE OF COOLER AIR CONTINUES TO PUSH DOWN THE
LAKE. A WEAK CONVERGENCE BAND HAS SET UP OVER NERN IL...WITH WINDS
NNWLY AT ORD AND NNELY AT MDW AND THE OTHER TAF SITES. EXPECT THAT
THIS BAND SHOULD WEAKEN THROUGH THE MORNING AND WINDS WILL BECOME
PREVAILING NNELY...VEERING NELY BY EARLY AFTERNOON. THIS
CONVERGENCE BAND AND RELATIVELY COOLER AIR OVER WARMER LAKE WATER
HAS SET UP A WEAK LAKE EFFECT REGIME...THOUGH LOW INVERSION
HEIGHTS AND WEAK INSTABILITY SHOULD LIMIT THE LAKE EFFECT TO MVFR
CIGS. AN ISOLD LIGHT SHOWER IS NOT OUT OF THE QUESTION...BUT IF
ANY DEVELOP THEY WOULD BE WEAK AND FLEETING. BY LATE MORNING OR
EARLY AFTERNOON...DRIER AIR FILTERING OVER THE AREA AS THE HIGH
PRESSURE CONTINUES TO SPREAD OVER THE REGION WILL ALLOW FOR SKIES
TO CLEAR OUT AS WINDS GRADUALLY VEER MORE ELY BY THIS EVENING AND
THEN SELY OVERNIGHT TONIGHT.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE WITH CIG TRENDS.
* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT...VFR. CHANCE SHRA LATE.
WEDNESDAY AND THURSDAY...CHANCE SHRA/TSRA...OTHERWISE VFR.
FRIDAY...CHANCE SHRA EARLY. COLD FRONTAL PASSAGE EARLY WITH SHARP
WIND DIRECTION SHIFT FROM SLY TO NWLY.
FRIDAY NIGHT THROUGH SUNDAY...VFR. WX NIL.
KREIN
&&
.MARINE...
307 AM CDT
STRONG HIGH PRESSURE CONTINUES TO SPREAD INTO THE UPPER GREAT
LAKES AS THE COLD FRONT PUSHES INTO THE OHIO VALLEY. A SECONDARY
SURGE OF COOLER AIR SPREADING DOWN THE LAKE HAS HELPED INCREASE
WINDS TO AROUND 30KT THROUGH THE EARLY MORNING HOURS. AS THE THE
CENTER OF THE HIGH SLIDES TO THE SOUTHEAST INTO THE EASTERN GREAT
LAKES MONDAY NIGHT...THE GRADIENT WILL RELAX...ALLOWING WIND
SPEEDS TO DECREASE AND DIRECTION TO VEER FROM GENERALLY NORTHERLY
TODAY TO SOUTHERLY BY TUESDAY MORNING. THE SOUTH WINDS WILL
PERSIST THROUGH THURSDAY AND THEN VEER MORE SOUTHWESTERLY BY
FRIDAY AS DEEP LOW PRESSURE MOVES INTO SOUTH CENTRAL CANADA AND A
STRONG COLD FRONT APPROACHES THE UPPER MISSISSIPPI VALLEY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014 UNTIL 4 PM TUESDAY.
IN...BEACH HAZARDS STATEMENT...INZ001 UNTIL 4 PM TUESDAY.
BEACH HAZARDS STATEMENT...INZ002 UNTIL 10 PM MONDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 4 PM
TUESDAY.
SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 11 PM MONDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Lincoln IL
1000 AM CDT Mon Sep 16 2013
.DISCUSSION...
ISSUED 1000 AM CDT Mon Sep 16 2013
Stratocumulus deck continues to thin out over a good part of
central Illinois this morning, with the northern edge basically
along I-74 from Galesburg to near Bloomington. However, some
higher clouds evident in satellite imagery spreading eastward over
the state. Cu-rule off the RAP model continues to show some
erosion of the lower cloud deck as drier air advects in from the
northeast.
Have sent some updated grids to bump up the winds and adjust the
dew points a bit. Temperatures still look good. The changes do not
require a change to the zone forecasts at this point.
Geelhart
&&
.AVIATION...
ISSUED 655 AM CDT Mon Sep 16 2013
Broken to overcast stratus/stratocumulus clouds with bases 500-1.5k ft
over central IL terminals early this morning (BMI at 300 ft) to
gradually lift to MVFR ceiling later this morning. Low clouds
should then scattered out during midday, occurring first along
northern airports along I-74 with broken cirrus clouds today. Some
MVFR vsbys of 3-5 miles over eastern IL at times especially at BMI
will lift to VFR vsbys by mid morning 14-15Z. Fair skies expected
after sunset tonight with scattered cirrus clouds and patchy light
fog with MVFR vsbys possible over eastern IL after 08-09Z. Northeast
winds around 10 kts with few gusts around 15 kts this morning to
diminish between 5-10 kts during the mid/late afternoon and veer ENE
around 5 kts tonight. Cold front near the Ohio River and MO/AR
border to keep convection south of central IL next 24 hours. 1030
MB Canadian high pressure around Lake Superior to drift southeast
across the Great Lakes region the next 24 hours and bring fair
weather to central IL.
07
&&
.PREV DISCUSSION...
ISSUED 257 AM CDT Mon Sep 16 2013
Cold front has moved through the FA this morning...stretching
along the Ohio River Valley while cooler air moves into place for
much of the Midwest. Northeasterly winds have settled in as a
surface high pressure, centered in northern MN, builds back into
the Midwest. Persistent upper level ridging over the Rockies and
the high plains providing a source of warming later in the
forecast...but for the next couple of days the temperatures are
rather cool. Into the remainder of the week, the forecast becomes
problematic almost immediately with a return of pops and a lack of
consistency in operational models. Low chance pops dominate
between a shortwave moving through Tuesday night/Wednesday and an
actual front on Thu night/Friday. On the other side of Friday
night...next weekend dries back out. Though breaks in the rain is
expected between Wednesday afternoon and Thursday night, models are
filling the gap with low pops.
SHORT TERM...Today and tomorrow...
Slow drying out behind the boundary with cooler temps expected
today. Clearing of clouds slowly as high pressure builds into the
region. Some clearing to the NW will work into the region...though
plenty of remnant clouds will move in from the SW and convection
behind the front in MO. Variable clouds through the day will
dissolve into the evening hours, clearing out and assisting
efficient radiational cooling and a temp drop into the 50s.
Tomorrow the winds get a small southerly component and the general
moderation of the air mass begins and temperatures start to climb a
couple degrees. That being said, clouds should be on the increase
so cooling tomorrow night should be impeded by the increasing
cloud cover. Pops return to forecast tomorrow afternoon in the
east and into the overnight, although concern for speed of onset of
QPF in general with the wave moving much faster in 00Z runs.
LONG TERM...Wednesday through Sunday...
Temperatures moderating somewhat by Wednesday due to a eastward
trending of the western mid level thermal ridge. Expect some
variability in the guidance as the portrayal of the next system
becomes clearer, right now being torn between the warmth under the
ridge and the threat of advancing rain. Pops move in Tues night
and continue through Friday with a lack of consistency for GFS and
ECMWF, as a result muddying the AllBlend. In addition, models
attempting a slow progression of initial wave and create an
interaction between remnant energy aloft and developing boundary
as another upper trof pushes into the region. Both ECMWF and GFS
fill the gap with pops across the board, so the AllBlend follows
suit. GFS and ECMWF are alternating being the most aggressive with
the strength and depth of the wave...and the QPF as well. For now,
the forecast remains rather diffuse and generous with the pops.
Best chances for precipitation beyond Wednesday looks to be in the
Thursday night/Friday time frame, associated with a cold front as
an aggressive trof digs in over the upper Midwest.
HJS
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
318 PM CDT MON SEP 16 2013
.SYNOPSIS...
ISSUED AT 317 PM CDT MON SEP 16 2013
LATEST SFC ANALYSIS WAS INDICATING HIGH PRESSURE DOMINATING THE
WESTERN GRT LKS AND UPPER MS RVR VALLEY. SUBSIDENCE FROM THE HEART
OF THIS FEATURE AND UPPER LEVEL RIDGING HELPING ERODE STRATOCU
FIELDS IN THE CWA...BUT SOME CLOUD FIELDS HOLDING FIRM ACRS SOUTH
CENTRAL INTO SOUTHEASTERN IA. ALOFT...WATER VAPOR IMAGERY WAS
INDICATING LINGERING MONSOONAL MOISTURE FIELDS ACRS THE CENTRAL
PLAINS OVER TO THE OH RVR/TN VALLEY REGIONS...WHILE MOISTURE OFF
INGRID SURGES INLAND ACRS MEX/SOUTHERN TX. UPSTREAM WAVE NOTED
ACRS THE NORTHWEST PLAINS ON WESTERN FLANK OF UPPER RIDGE AXIS.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 317 PM CDT MON SEP 16 2013
TONIGHT...WILL FOLLOW LATEST RAP LLVL MOISTURE/RH GUIDANCE WHICH
SUGGESTS A CONTINUED CLEARING OF THE STRATOCU EXCEPT MAYBE THE FAR
SOUTHWESTERN CWA THROUGH THIS EVENING. IT ALSO SUGGESTS LLVL FLOW
TO VEER TO THE EAST-SOUTHEAST OVERNIGHT AND POSSIBLY START ADVECTING
MORE HIGHER RH LEVELS/STRATOCU FROM SOUTHEAST IL/IND LATE TONIGHT
AFTER MIDNIGHT. FOR NOW WILL MAINTAIN MOSTLY CLR SKIES OVERNIGHT
FOR BULK OF THE EASTERN HALF OF THE CWA AND BANK ON COOL LOWS IN THE
40S WITH LOW/DRY AMBIENT SFC DPTS. BUT SOME BUST POTENTIAL ON THE LOW
SIDE IF THE CLOUDS DO ADVECT IN FROM THE EAST LATER TONIGHT ALONG
WITH HIGHER DPTS FROM THOSE SAME AREAS. WILL KEEP LOWS IN THE LOW TO
MID 50S IN THE SOUTHWEST THIRD WITH EXPECTED MID DECK/HIGHER CLOUD
INCREASE LATER TONIGHT FROM THE SOUTHWEST IN THOSE AREAS. ELEVATED
WARM AIR ADVECTION PROCESSES ASSOCIATED WITH RIDGE-RIDING WAVE
MENTIONED ABOVE PUSHING ACRS EASTERN NEB AND WESTERN IA TO TAP IN THE
LINGERING MONSOONAL MOISTURE AND PRODUCE SHOWERS OVERNIGHT...BUT
RIDGING AND DRY AIR IN PLACE TO MAKE FOR MOST OF THE CWA REMAINING
DRY THROUGH 12Z TUE. MUCH OF INITIAL LIFT FROM APPROACHING UPPER WAVE
TO GO INTO TOP-DOWN SATURATION PROCESSES WITH VIRGA TO LIGHT
SHOWERS/SPRINKLES ACRS THE SOUTHWEST THIRD TOWARD DAYBREAK.
TUESDAY...DESPITE SOME DECENT MODEL INDICATED ELEVATED THTA-E
ADVECTION AND CONVERGENT REGIONS PUSHING ACRS THE SOUTHWESTERN
THIRD TO HALF OF THE DVN CWA AS THE DAY PROGRESSES...THE BATTLE
WILL BE ON WITH LARGE DRY AIRMASS TO THE EAST. LIKE THE PREVIOUS
SHIFT MENTIONED...SHARP MOISTURE AND PRECIP GRADIENTS MAY DEVELOP
LOCALLY WITH SOME AREAS/IN THE FAR SOUTHWEST/ GETTING UP TO A
QUARTER INCH OF RAIN BY MID AFTERNOON...AND AREAS EAST OF THE MS RVR
ESPECIALLY EAST CENTRAL AND NORTHEAST REMAINING DRY THROUGH 00Z WED.
WILL SPREAD IN POPS GENERALLY FROM WEST-SOUTHWEST TO EAST IN
DECREASING FASHION TUE. BUT SOME AREAS PROBABLY WARRANT CATEGORICAL
POPS WEST OF THE MS RVR. EXPECT MAINLY SHOWERS IN DECLINING FASHION
AS THEY SPREAD EASTWARD AND ENCOUNTER THE DRY AIR...BUT PROGGED
MID LEVEL MUCAPES OF 200-500 J/KG IF CORRECT...SUPPORTS ISOLATED
EMBEDDED THUNDER IN THE SOUTHWESTERN HALF ON TUE. TEMPS WILL BE A
CHALLENGE TUE DEPENDING ON CLOUD COVER AND EVAPO-COOLING FROM
PRECIP. WILL GO WITH COOLER VALUES HELD DOWN IN THE 60S IN THE
WEST WITH EARLIER ARRIVAL OF CLOUDS AND PRECIP...WARMER IN THE LOW
70S EAST OF THE MS RVR. ..12..
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 317 PM CDT MON SEP 16 2013
ACTIVE WX WILL BE SEEN ACROSS THE MIDWEST FOR THE REMAINDER OF THE
WORK WEEK WITH SEVERAL CHANCES FOR RAIN.
RAIN THAT MOVES INTO THE AREA TUESDAY AFTERNOON WILL OVERSPREAD THE
AREA TUESDAY NIGHT/WED. AS THE OVERALL FORCING WEAKENS ON WEDNESDAY
THE AREAL COVERAGE OF PRECIPITATION WILL DECREASE WEDNESDAY
AFTERNOON.
WED NIGHT/THURSDAY THE NEXT ROUND OF FORCING MOVES THROUGH THE AREA
HELPING TO RE-DEVELOP NEW CONVECTION. A RESPECTABLE LLJ DEVELOPS WED
NIGHT WHICH SHOULD RESULT IN CONSIDERABLE NOCTURNAL CONVECTION AFTER
MIDNIGHT AND INTO THURSDAY MORNING.
THE APPROACHING COLD FRONT ON THURSDAY IS EXPECTED TO HELP MAINTAIN
CONVECTION DURING THE AFTERNOON. THE AMOUNT OF CLOUD COVER MAY HOLD
DOWN TEMPERATURES SOMEWHAT BUT THEY SHOULD STILL BE CLOSE TO NORMAL.
THURSDAY NIGHT ON...
THE MODEL CONSENSUS HAS HIGH CHC/LIKELY POPS FOR THURS NIGHT AS THE
NEXT FRONT MOVES THROUGH THE AREA. THE FRONT WILL CLEAR THE AREA ON
FRIDAY SO ONLY SCHC/LOW CHC POPS ARE GIVEN BY THE MODEL CONSENSUS
FOR THE EASTERN HALF OF THE CWFA.
COOL CANADIAN HIGH BUILDS INTO THE GREAT LAKES FOR FRIDAY NIGHT
THROUGH SUNDAY NIGHT. THE MODEL CONSENSUS GIVES DRY CONDITIONS WITH
TEMPERATURES AVERAGING BELOW NORMAL.
SOUTHERLY FLOW DEVELOPING ON MONDAY WILL ALLOW TEMPERATURES TO AGAIN
WARM. THE MODEL CONSENSUS HAS DRY CONDITIONS FOR MONDAY WITH CHC
POPS FOR MONDAY NIGHT. ..08..
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1226 PM CDT MON SEP 16 2013
DRYING SUBSIDING AIR SLOWLY PUSHING IN FROM THE WEST CLEARING MVFR
STRATOCU AT MLI/DBQ...BUT MAY TAKE 1-2 MORE HRS AT CID/BRL BEFORE
CIGS SCATTER OUT OR CLEAR. SOME CONCERN MVFR BKN-OVC CIGS AT CID
MAY HOLD ON UNTIL AFTER 3 PM CDT THIS AFTERNOON. OTHERWISE EXPECT
MAINLY CLEAR SKIES OVERNIGHT WITH LIGHT EASTERLY SFC WINDS.
HOPEFULLY ENOUGH LOWERING OF SFC DPTS AND SFC WIND MAINTENANCE TO
LIMIT FOG POTENTIAL AND WILL LEAVE OUT OF TAFS FOR NOW...BUT SOME
MVFR FOG POSSIBLE AT DBQ/MLI/CID AFTER 06Z TONIGHT. NEXT SYSTEM
WILL THEN APPROACH OUT OF THE PLAINS AND BRING THICKENING CLOUDS
MAINLY VFR LATE TONIGHT INTO TUE MORNING. SHORT RANGE MODELS
VARY ON IF SOME ELEVATED/HIGH BASED SHOWERS GET IN THE VCNTY OF
BRL AND CID FROM THE WEST BY MID TO LATE TUE MORNING. FOR NOW WILL
LEAVE OUT MENTION IN THE TAFS BUT LATER AVIATION FCSTS WILL HAVE
TO BETTER DEFINE INCOMING PRECIP WINDOWS FOR TUE. ..12..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...12
SHORT TERM...12
LONG TERM...08
AVIATION...12
AREA FORECAST DISCUSSION
NWS WICHITA KS
1143 PM CDT SUN SEP 15 2013
.SYNOPSIS...
ISSUED AT 250 PM CDT SUN SEP 15 2013
A COLD FRONT STRETCHING FROM NORTHEAST TO CENTRAL AND
SOUTHWEST KANSAS IS KEEPING ON ITS SOUTHEAST TRACK. THIS FRONT WILL
PUSH THROUGH THIS EVENING...AND A RIDGE WILL BE ON ITS TAILS FOR
MONDAY. A FAIRLY ACTIVE PATTERN IS IN PLACE TO KEEP SYSTEMS MOVING
ACROSS THE CONUS.
&&
.UPDATE...
ISSUED AT 701 PM CDT SUN SEP 15 2013
PUT OUT A QUICK UPDATE TO TWEAK STORM CHANCES OVER THE NEXT FEW HOURS.
CURRENT THINKING IS THAT THE STORMS SHOULD STAY CONFINED TO
SOUTHERN KS FOR THE NEXT FEW HOURS. THERE SHOULD BE A GRADUAL
INCREASE IN COVERAGE TOWARD 06Z AS ISENTROPIC LIFT NORTH OF THE
FRONT INCREASES WITH SOME OF THIS ACTIVITY TRYING TO SPREAD BACK
INTO CENTRAL KS.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 250 PM CDT SUN SEP 15 2013
AS MENTIONED IN THE SYNOPSIS...THE COLD FRONT SHOULD CONTINUE TO
SLIDE THROUGH THE REST OF KANSAS AND INTO OKLAHOMA THIS EVENING
AND TONIGHT. SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED TO
BUBBLE UP ALONG AND BEHIND THIS FRONTAL FEATURE THIS AFTERNOON
GIVEN DAYTIME HEATING AND . SOME OF THE STORMS COULD BE STRONG
WITH ABOVE 1K J/KG CAPE VALUES MAINLY IN SOUTH CENTRAL
KANSAS...HOWEVER 0-6KM BULK SHEAR VALUES ARE LESS THAN 30KTS
ACCORDING TO THE MODELS DURING THIS RESPECTIVE TIME FRAME FOR ALL
BUT THE RUC WHICH HAS VALUES JUST AT 40KTS. PRECIPITATION ACTIVITY
IS STILL ANTICIPATED TO LINGER INTO MUCH OF MONDAY AND TUESDAY
WHEN ANOTHER SHORTWAVE IN THE MID LEVELS MOVES THROUGH THE AREA.
ANOTHER TROUGH AT 500MB AND 700MB IS GOING TO MOVE ONSHORE ON
TUESDAY...WHILE THE 850MB TROUGH HALTS AND STARTS TO DEVELOP ALONG
THE FRONT RANGE. EVENING POPS ON TUESDAY WERE SLIGHTLY DROPPED
FROM THE PREVIOUS FORECAST...BUT THE MAIN TRENDS FOR ALL OTHER
PARAMETERS WERE MAINTAINED. COOLER AIR ON MONDAY AND CLOUD COVER
WILL KEEP HIGHS BELOW SEASONAL NORMAL BY 5 DEGREES IN SOUTH
CENTRAL KANSAS AND AS MUCH AS 10 DEGREES IN CENTRAL KANSAS.
TUESDAY SHOULD REBOUND BACK TO ABOVE NORMAL IN THE MID TO UPPER
80S.
JUANITA
.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 250 PM CDT SUN SEP 15 2013
WEDNESDAY THRU THURSDAY: IN THIS TIME FRAME...THE NEXT SYSTEM IS
EXPECTED TO MOVE THROUGH THE PLAINS. WHILE THE CENTER OF THE LOW
STAYS ACROSS THE CANADIAN AND U.S. BORDER AND MOVES THE FRONT ON
WEDNESDAY INTO THURSDAY...THERE ARE MODEL DIFFERENCES IN ITS TIMING.
ECMWF IS MORE PROGRESSIVE WITH PUSHING THE FRONT THROUGH THE AREA.
THERE COULD BE A CHANGE IN PRECIP ACTIVITY WITH THIS DIFFERENCE.
POPS WERE SLIGHTLY INCREASED FOR THURSDAY AND THURSDAY EVENING WITH
A SMIDGEN OF BETTER CONSISTENCY.
FRIDAY THRU SUNDAY: CURRENT MODEL PREDICTIONS OF THIS TIME FRAME MAKE IT
APPEAR THAT A RIDGE WILL BE IN PLACE. MODEL DISCREPANCIES BEGIN AT
THE START OF NEXT WEEK WHICH MAY MAKE AN IMPACT TO THE FORECAST
FOR SUNDAY DEPENDING ON THE POTENTIAL PROGRESSIVE NATURE OF THE
SYSTEM. THIS IS TOO FAR OUT FOR ANY CERTAINTY IN EITHER PREDICTION
OF THE NEXT SYSTEM TO MOVE THROUGH THE CENTRAL UNITED STATES.
SLIGHT CHANCES WERE PUT IN FOR SUNDAY...BUT AGAIN CONFIDENCE IS
LOW AT THIS TIME.
JUANITA
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1139 PM CDT SUN SEP 15 2013
AVIATION ISSUES WILL REMAIN STORMS TONIGHT THROUGH MOST OF MON
ALONG WITH LOWERING CIGS.
SCT STORMS ARE EXPECTED TO CONTINUE OVERNIGHT AND INCREASE IN
COVERAGE AS AN UPPER IMPULSE LIFTS ACROSS WEST-CENTRAL KS LATE
TONIGHT. SEVERE STORMS ARE NOT EXPECTED WITH THIS ACTIVITY. MVFR
CIGS CURRENTLY COVER CENTRAL KS AND WILL SLOWLY SPILL SOUTH
TONIGHT. DID GO AHEAD AND RUN WITH A FEW HOURS OF IFR LEVELS AT
KRSL AFTER 09Z BUT FEEL MVFR LEVELS WILL BE MORE COMMON. BY EARLY
MON EVENING THE UPPER WAVE WILL BE LIFTING OUT OF THE AREA
DECREASE STORM CHANCES.
LAWSON
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 65 78 65 86 / 60 50 30 30
HUTCHINSON 62 75 63 85 / 50 50 30 30
NEWTON 61 74 62 83 / 50 50 30 30
ELDORADO 63 78 63 84 / 60 50 30 30
WINFIELD-KWLD 67 81 65 86 / 60 60 30 30
RUSSELL 58 72 61 86 / 40 40 40 30
GREAT BEND 59 73 62 85 / 40 40 40 30
SALINA 60 73 62 84 / 40 40 40 40
MCPHERSON 61 74 63 84 / 50 40 30 40
COFFEYVILLE 66 83 65 86 / 50 60 40 40
CHANUTE 64 78 63 85 / 60 60 40 40
IOLA 63 76 62 84 / 50 50 40 40
PARSONS-KPPF 65 81 64 85 / 50 60 40 40
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
1055 PM EDT TUE SEP 17 2013
.UPDATE...
ISSUED AT 1055 PM EDT TUE SEP 17 2013
HAVE UPDATED THE FORECAST FOR THE NEAR TERM SKY/T/TD GRIDS BASED ON
CURRENT OBS AND TRENDS. THE 00Z NAM12 AND LATEST HRRR STILL KEEP MOST
OF THE SHOWERS WEST OF THE AREA THROUGH 12Z. UPDATES HAVE BEEN SENT
TO THE NDFD AND WEB SERVERS.
UPDATE ISSUED AT 745 PM EDT TUE SEP 17 2013
23Z SFC ANALYSIS SHOWS HIGH PRESSURE RETREATING OFF TO THE EAST IN
THE FACE OF APPROACHING LOW PRESSURE. THIS TRANSITION WILL BRING
LOWER CIGS TO EAST KENTUCKY TOWARD DAWN ALONG WITH A SMALL CHANCE OF
SHOWERS IN THE WESTERN PARTS OF THE AREA. THESE CLOUDS SHOULD LIMIT
THE FOG FORMATION TO THE DEEPER VALLEYS GENERALLY EAST OF JKL.
LIKEWISE...EXPECT A RIDGE TO VALLEY TEMPERATURE SPLIT OVER THE
EASTERN PARTS OF THE CWA WITH MILDER TEMPERATURES AND HIGHER
DEWPOINTS SEEN ELSEWHERE. HAVE UPDATED THE FORECAST GRIDS FOR THESE
THOUGHTS...ESSENTIALLY TWEAKING LOW TEMPS...ADJUSTING THE DIURNAL
CURVE...AND PULLING POPS WESTWARD THROUGH SUNRISE PER THE LATEST
NAM12 AND HRRR. THESE UPDATES HAVE BEEN SENT TO THE NDFD AND WEB
SERVERS...ALONG WITH A FRESHENED SET OF ZONES.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 250 PM EDT TUE SEP 17 2013
THE MODELS ARE IN PRETTY GOOD AGREEMENT. HIGH PRESSURE BUILD IN
BEHIND THE FRONT THAT MOVED THROUGH THE AREA YESTERDAY. THIS FRONT
WILL MOVE BACK TO THE NORTH AS A WARM FRONT THIS EVENING AND ALONG
WITH THE ISENTROPIC LIFT...WILL BE ABLE TO PRODUCE SOME ISOLATED TO
SCATTERED LIGHT RAIN SHOWERS LATE TONIGHT AND TOMORROW. THE FRONT AND
THE RAIN WILL CONTINUE TO MOVE TO THE NORTHEAST. THIS WILL ALLOW THE
TEMPS TO WARM UP AND FOR THE HUMIDITY TO INCREASE. FOR
TEMPERATURES...USED THE MODEL BLEND AND THE BUMPED THEM UP A COUPLE
OF DEGREES FOR THE HIGHS ON WEDNESDAY. THIS WAS A BIT OF A COMPROMISE
BETWEEN THE MOS AND THE RAW MODEL OUTPUT.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 250 PM EDT TUE SEP 17 2013
HIGH PRESSURE WILL BE FIRMLY IN CONTROL AT THE START OF THE PERIOD.
WHILE SOME MEAGER INSTABILITY WILL DEVELOP THURSDAY AND FRIDAY
AFTERNOONS...NOT MUCH OF A TRIGGER TO REALLY GET ANYTHING GOING. IN
FACT...INSTABILITY IS SO MEAGER...OPTING TO TREND POPS DOWNWARD BOTH
DAYS. NAM IS THE OUTLIER WITH A BIT MORE INSTABILITY...BUT ALSO
APPEARS TO BE BRINGING HIGHER DEWPOINTS IN MUCH TOO QUICK...SO HAVE
OPTED TO DISCOUNT THIS MODEL FOR THE TIME BEING.
MODELS CONTINUE THE TREND OF SLOWING DOWN THE COLD FRONT FOR THE
UPCOMING WEEKEND. IT NOW LOOKS LIKE THE FRONT SHOULD CROSS EASTERN
KENTUCKY FROM LATE FRIDAY NIGHT THROUGH SATURDAY. WILL CONTINUE THE
HIGH POPS DURING THIS PERIOD. HAVE TRENDED THE THUNDER POTENTIAL
DOWNWARD GIVEN THE LACK OF ANY SUBSTANTIAL INSTABILITY. SOME
ELEVATED THUNDER MAY BE POSSIBLE AT TIMES...BUT SURFACE INSTABILITY
NEVER GETS THAT STRONG...EVEN INTO SATURDAY AFTERNOON. FRONT MAY
LINGER ACROSS THE SOUTHEAST INTO SUNDAY MORNING BEFORE FINALLY
EXITING BY SUNDAY AFTERNOON...ALLOWING FOR DRY WEATHER TO END THE
WEEKEND. WITH HIGH PRESSURE BUILDING IN SUNDAY NIGHT...A QUIET START
TO THE NEW WEEK IS ANTICIPATED. HIGHS THURSDAY AND FRIDAY WILL
RETURN TO SLIGHTLY ABOVE NORMAL WITH PLENTY OF SUNSHINE...BUT WILL
TREND BACK BELOW NORMAL FOR THE WEEKEND INTO EARLY NEXT WEEK AS
COOLER WEATHER SETTLES IN BEHIND THE COLD FRONT.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 750 PM EDT TUE SEP 17 2013
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGHOUT THE TAF PERIOD.
VALLEY FOG WILL BE VERY MINIMAL TONIGHT...ASIDE FROM FAR EASTERN
PARTS OF THE AREA. LIGHT SHOWERS MAY MOVE INTO THE AREA TOWARD DAWN
FROM THE WEST GENERALLY CAUSING CIGS TO DROP DOWN TO AROUND 4K
FT...HOWEVER CIGS AND VSBY ARE EXPECTED TO REMAIN VFR THROUGHOUT THE
PERIOD. HAVE INCLUDED A VCSH FOR THE DAYTIME HOURS. WINDS WILL BE
LIGHT AND VARIABLE THROUGH THE FORECAST.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...JJ
LONG TERM...KAS
AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
311 AM CDT MON SEP 16 2013
.DISCUSSION...
DESPITE AN ANCHORED UPPER LEVEL RIDGE ACROSS THE LOWER MISS
VALLEY...MID AND HIGH CLOUDS ARE PLENTIFUL THIS MORNING ACROSS
ALL OF THE SOUTHERN PLAINS/LOWER MISS VALLEY AND THIS IS HELPING
TO HOLD EARLY MORNING LOW TEMPERATURES UP A BIT. DRIER AIR IN THE
LOW LEVELS TRYING TO HOLD ON NORTH OF THE I-20 CORRIDOR TODAY BUT
65-70+ DEWPOINTS ACROSS OUR EXTREME SOUTHERN ZONES WILL SLOWLY
BEGIN MAKING A COMEBACK OVER THE NEXT 24 HOURS WITH HIGHER
HUMIDITY ENDING A BRIEF BREAK FROM THE HEAT WE ENJOYED THIS
WEEKEND.
THETAE RIDGING IN THE 850-700MB LAYER MARKS THE LEADING EDGE OF
THE SLOWLY ADVANCING HIGHER MOISTURE CONTENT AND THIS AXIS WILL BE
LOCATED ACROSS OUR WESTERN MOST ZONES TODAY. NAM IS SPITTING OUT A
LITTLE QPF IN THIS REGION TODAY...AS IS THE LATEST RAP OUTPUT AND
FOR THIS REASON...HAVE ADDED ISOLATED TSRA TO OUR WESTERN 2/3RDS
FOR THIS AFTN/EVNG WHICH MATCHES UP WELL WITH SPC`S DAYONE
OUTLOOK. OTHERWISE...THE FORECAST FOR MUCH OF THE WORK WEEK WILL
BE BEST DEFINED BY A SHRINKING UPPER LEVEL RIDGE AXIS AND AN EVER
EXPANDING ATMOSPHERIC MOISTURE PROFILE. TEMPERATURES WILL CONTINUE
TO RUN NEARLY 10 DEGREES ABOVE NORMAL FOR MID SEPTEMBER.
MEDIUM RANGE PROGS REMAIN IN EXCELLENT AGREEMENT WITH THE
BREAKDOWN OF THIS RIDGE AND THE DEVELOPMENT OF AN UPPER LEVEL
TROUGH IN THE LEE OF THE ROCKIES BY FRIDAY. THIS TROUGH WILL BE
ACCOMPANIED BY A COLD FRONT LATE FRIDAY NIGHT INTO SATURDAY AND
APPEARS TO HAVE PLENTY OF LIFT AND MOISTURE TO WORK WITH.
THUS...GOOD RAIN CHANCES APPEAR TO ACCOMPANY THIS TROUGH FOR
FRIDAY THROUGH AT LEAST SATURDAY NIGHT. THE GFS IS HAVING SOME
FEEDBACK PROBLEMS BUT A SLOWING FRONT AND PARALLEL FLOW ALONG THE
BOUNDARY WOULD SUPPORT SOME DESCENT RAINFALL RATES AND TOTALS. FOR
NOW...HAVE RAISED THE DAY 5-6 POP FORECAST SLIGHTLY AND WILL
CONTINUE THIS TREND IF NECESSARY AS THE EVENT GETS CLOSER...
ASSUMING WE KEEP GOOD CONTINUITY IN THE MEDIUM RANGE.
PRELIM TO FOLLOW...13.
&&
.AVIATION...
IR SATELLITE INDICATES A FAIRLY EXTENSIVE CIRRUS SHIELD THIS MORNING
ACROSS THE REGION ALONG WITH SOME HIGH BASED STRATOCU IN E TX/NW LA.
VFR CONDITIONS WILL PREVAIL IN THIS ENVIRONMENT AS ANY POTENTIAL FOG
DEVELOPMENT WILL LIKELY BE MITIGATED BY CLOUD COVER...ALTHOUGH CAN
NOT RULE OUT PERIODS OF MVFR VSBYS AT OUR USUAL FOG PRONE TERMINALS.
LIGHT AND VRBL WINDS THIS MORNING TO RETURN TO EASTERLY FOR MUCH OF
THE DAY...WITH SOME PERIODS OF SE FLOW AROUND 5-10 KTS OVER THE WRN
HALF OF THE REGION...WHERE INCREASING GULF MOISTURE WILL ALLOW FOR
THE RETURN OF SOME ISOLD AFTERNOON CONVECTION. DO NOT ANTICIPATE ANY
MORE THAN VCTS MENTION IN THE E TX TAFS AND POSSIBLY SHV AS WELL.
/19/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 96 72 96 73 96 / 20 20 20 20 20
MLU 96 69 95 69 95 / 10 10 20 20 20
DEQ 94 65 93 68 95 / 20 20 20 20 20
TXK 94 68 93 70 95 / 20 20 20 20 20
ELD 94 66 94 67 95 / 10 10 20 20 20
TYR 96 74 95 74 96 / 20 20 20 20 20
GGG 96 72 95 73 96 / 20 20 20 20 20
LFK 96 72 95 72 96 / 20 20 20 20 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
13/19
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1211 PM EDT MON SEP 16 2013
.SYNOPSIS...
HIGH PRESSURE WILL SLOWLY BUILD INTO THE AREA THIS EVENING...UNTIL
SO LOOK FOR CLOUDS TO HANG AROUND. DRY AND SEASONAL WEATHER TAKES
HOLD THROUGH MID WEEK. A COLD FRONT WILL CROSS LATER THIS WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CLOUDS HAVE QUICKLY FILLED IN DUE TO AN AUTO CONVECTIVE
ATMOSPHERE. LATEST HRRR COINCIDES WELL WITH THE REGIONAL RADAR
MOSAIC WITH ISOLD - SCT RW DROPPING S FROM LAKE ERIE. ISOLD
SHOWERS ARE POSSIBLE IN THE I-80 AREA THROUGH LATE AFTN. FARTHER
S...DO NOT EXPECT ANY MEASURABLE QPF SO WILL CARRY SPRINKLES. RUC
SOUNDINGS ILLUSTRATE MARGINAL INSTABILITY GIVEN LAKE DELTA TS.
INVERSION HEIGHT LOWERS TO 4-5KFT DURING THE DAY OFFSETTING ANY
LAKE INDUCED INSTABILITY. TEMPS ON TRACK WITH NO CHANGES PLANNED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
THE SHRTWV IS PROGGED TO EXIT THE RGN THIS EVE. STILL SOME QN ON
HOW LONG THE STRATOCU WILL REMAIN ACRS THE AREA. KEPT MCLDY SKIES
INTO THE EVE WITH A GRDL CLRG TREND OVRNGT AS THE FLOW BECOMES
NERLY AND SBSDNC INCRS WITH BLDG HIGH PRES. THE HIGH WL SHIFT EWD
WED WRM AIR ADVCTN BRINGING A GRDL INCRS IN CLDS LT IN THE DAY.
SHWR/TSTM CHCS WL INCR WED NGT AND THU AS A SHRTWV MOVES ACRS THE
GT LKS/OH VLY RGN. EXP LOWS TNGT AND TUE NGT FM UPR 30S/NR 40 N TO
MD 40S S...WHICH SHOULD PRECLUDE ANY FROST MENTION IN THE FCST.
EXP TEMPS TO MODERATE TO NR OR ABV SEASONAL AVGS BY MD WK.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
RAIN CHCS WL INCRS DURING THE LATTER HALF OF THE WEEK AS MDLS ARE
IN AGRMNT IN SCENARIO OF A DEEPENING TROF WITH ITS ADVN ACRS THE
GREAT LAKES. CURRENT GFS AND ECMWF TIMING SUGGESTS CDFNT/UPR TROF
AXIS PASSAGE FOR SATURDAY...HENCE THE DRYING TREND DEPICTED FOR
THE START OF THE NEW WEEK.
WARM ADVCTN IN ADVN OF THAT TROF WL LIKELY SPPRT TEMPS AOA THE
SEASONAL AVERAGES UNTIL FRONTAL PASSAGE. WPC GUIDANCE GENL DEPICTS
THIS AND WAS UTILIZED WITH MINIMAL VARIATION.
&&
.AVIATION /16Z MONDAY THROUGH FRIDAY/...
A CDFNT WL COMPLETE PASSAGE ACRS THE UPR OH REGION THIS MRNG
ACCOMPANIED BY A BROAD SWATH OF LOW AND MID LVL CLDINESS WITH RESIDUAL
LGT SHWRS. MOIST BNDRY LYR FM LAST NGTS RAIN WL SPPRT ISOLD AREAS
OF IFR VSBY AND ST...WHICH WL MIX OUT RAPIDLY AFTR DAYBREAK.
MVFR STRATOCU IS EXPECTED TO PERSIST THROUGH THE MRNG...BUT DRY
ADVCTN...SBSDNC...AND DVLPG NNE COMPONENT TO THE SFC WIND SHOULD
SPPRT VFR BY AFTN. BLDG HIGH PRES WL THEN MAINTAIN THAT CONDITION
THROUGH TNGT.
.OUTLOOK.../TUESDAY THROUGH FRIDAY/...
SHWRS WITH A THURSDAY WARM FRONT WL BRING THE NXT CHC FOR GENL RESTRICTIONS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
SYNOPSIS...98
NEAR TERM...98
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
851 AM EDT MON SEP 16 2013
.SYNOPSIS...
HIGH PRESSURE WILL SLOWLY BUILD INTO THE AREA THIS EVENING...UNTIL
SO LOOK FOR CLOUDS TO HANG AROUND. DRY AND SEASONAL WEATHER TAKES
HOLD THROUGH MID WEEK. A COLD FRONT WILL CROSS LATER THIS WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
RAIN IS ALMOST OUT OF THE AREA AT WHILE COLD FRONT IS CROSSING THE
SPINE OF THE APPALACHIANS. THERE WILL BE A BREAK IN PCPN FOR THE
ENTIRE AREA THIS MRNG...THEN ISOLD SHOWERS ARE POSSIBLE IN THE
I-80 AREA THIS AFTN. FARTHER S...DO NOT EXPECT ANY MEASURABLE
QPF. RUC SOUNDINGS ILLUSTRATE MARGINAL INSTABILITY GIVEN LAKE
DELTA TS. INVERSION HEIGHT LOWERS TO 4-5KFT DURING THE DAY
OFFSETTING ANY LAKE INDUCED INSTABILITY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
THE SHRTWV IS PROGGED TO EXIT THE RGN THIS EVE. STILL SOME QN ON
HOW LONG THE STRATOCU WILL REMAIN ACRS THE AREA. KEPT MCLDY SKIES
INTO THE EVE WITH A GRDL CLRG TREND OVRNGT AS THE FLOW BECOMES
NERLY AND SBSDNC INCRS WITH BLDG HIGH PRES. THE HIGH WL SHIFT EWD
WED WRM AIR ADVCTN BRINGING A GRDL INCRS IN CLDS LT IN THE DAY.
SHWR/TSTM CHCS WL INCR WED NGT AND THU AS A SHRTWV MOVES ACRS THE
GT LKS/OH VLY RGN. EXP LOWS TNGT AND TUE NGT FM UPR 30S/NR 40 N TO
MD 40S S...WHICH SHOULD PRECLUDE ANY FROST MENTION IN THE FCST.
EXP TEMPS TO MODERATE TO NR OR ABV SEASONAL AVGS BY MD WK.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
RAIN CHCS WL INCRS DURING THE LATTER HALF OF THE WEEK AS MDLS ARE
IN AGRMNT IN SCENARIO OF A DEEPENING TROF WITH ITS ADVN ACRS THE
GREAT LAKES. CURRENT GFS AND ECMWF TIMING SUGGESTS CDFNT/UPR TROF
AXIS PASSAGE FOR SATURDAY...HENCE THE DRYING TREND DEPICTED FOR
THE START OF THE NEW WEEK.
WARM ADVCTN IN ADVN OF THAT TROF WL LIKELY SPPRT TEMPS AOA THE
SEASONAL AVERAGES UNTIL FRONTAL PASSAGE. WPC GUIDANCE GENL DEPICTS
THIS AND WAS UTILIZED WITH MINIMAL VARIATION.
&&
.AVIATION /13Z MONDAY THROUGH FRIDAY/...
A CDFNT WL COMPLETE PASSAGE ACRS THE UPR OH REGION THIS MRNG
ACCOMPANIED BY A BROAD SWATH OF LOW AND MID LVL CLDINESS WITH RESIDUAL
LGT SHWRS. MOIST BNDRY LYR FM LAST NGTS RAIN WL SPPRT ISOLD AREAS
OF IFR VSBY AND ST...WHICH WL MIX OUT RAPIDLY AFTR DAYBREAK.
MVFR STRATOCU IS EXPECTED TO PERSIST THROUGH THE MRNG...BUT DRY
ADVCTN...SBSDNC...AND DVLPG NNE COMPONENT TO THE SFC WIND SHOULD
SPPRT VFR BY AFTN. BLDG HIGH PRES WL THEN MAINTAIN THAT CONDITION
THROUGH TNGT.
.OUTLOOK.../TUESDAY THROUGH FRIDAY/...
SHWRS WITH A THURSDAY WARM FRONT WL BRING THE NXT CHC FOR GENL RESTRICTIONS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
SYNOPSIS...98
NEAR TERM...98
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
726 PM EDT TUE SEP 17 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 421 PM EDT TUE SEP 17 2013
17Z WV IMAGERY AND RUC ANALYSIS INDICATED A WELL-DEFINED SHORTWAVE
LIFTING NE THROUGH ERN IA. DPVA...7H FGEN AND 305K ISENTROPIC ASCENT
ASSOC WITH THE SHORTWAVE HAS SUPPORTED AN AREA OF SHOWERS OVER
NORTHEAST IA. VIS SATELLITE HAS SHOWN AN EXPANSION OF DIURNAL CU
FROM MNM-DELTA-ALGER COUNTIES EASTWARD IN AN AREA OF HIGHER
DEWPOINTS (UPPER 40 TO LOWER 50S) AIDED BY SOUTHERLY FLOW OFF LAKE
MI AND BAY OF GREEN BAY. RDGG ALOFT AND AT THE SFC HAS KEPT THE REST
OF THE FCST AREA GENERALLY CLOUD FREE THIS AFTERNOON.
TONIGHT...MDLS SUGGEST THAT AS THE IA SHRTWV GRADUALLY LIFTS TO THE
NORTHEAST...MOISTURE WILL INCREASE AND BRING SOME LIGHT WAA PCPN
INTO THE AREA AS 300K-310K ISENTROPIC ASCENT SPREADS FROM SE MN AND
WRN WI TOWARD UPPER MI. THE NAM/GFS ARE STILL A BIT MORE AGGRESSIVE
IN BRINGING SOME LIGHT PCPN INTO THE CWA COMPARED TO THE GEM/ECMWF.
GIVEN THE VERY DRY ANTECEDENT AIRMASS...THE NAM/GFS MAY BE TOO QUICK
SO USED MORE OF A MODEL BLEND FOR POPS WITH ONLY A 30 PCT CHC OF
LIGHT SHOWERS TOWARD 12Z NEAR THE WI BORDER WITH SLIGHT CHC ACROSS
MUCH OF THE REST OF THE WEST HALF.
WEDNESDAY...GIVEN PREDICTED TRACK OF ERN IA SHORTWAVE EXPECT BEST
FORCING FOR SHRA TO BE MAINLY CENTRAL COUNTIES IN THE MORNING AND
THEN TO SPREAD INTO THE EASTERN COUNTIES IN THE AFTERNOON. HAVE ONLY
SLIGHT CHC POPS FOR SHRA WEST AWAY FROM BETTER FORCING ASSOC WITH
SHORTWAVE. MODEL MLCAPES OTHER THAN NAM SHOW ONLY MARGINAL
INSTABILITY OF A FEW HUNDRED J/KG AT BEST OVER THE AREA SO WILL ONLY
INCLUDED SLIGHT CHC MENTION OF TS IN THE GRIDS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 421 PM EDT TUE SEP 17 2013
LITTLE CHANGES TO THE LARGE SCALE PATTERN FOR THE LONG TERM PERIOD
OVER THE LAST 24 HOURS. AREA WILL BE UNDER WEAK UPPER RIDGING TO
START THE PERIOD...WHICH WILL LEAD TO BROAD WARM AIR ADVECTION AND
THE POTENTIAL FOR SOME SHOWERS/THUNDERSTORMS WEDNESDAY NIGHT INTO
THURSDAY AS A WARM FRONT LIFTS ACROSS THE AREA. BEST CHANCES ON
WEDNESDAY NIGHT WILL BE EARLY ON WHEN THE STRONGEST WARM AIR
ADVECTION MOVES THROUGH AND BEFORE THE DEEPER MOISTURE STARTS TO
CUTOUT. THIS BROAD WAA WILL ALSO LEAD TO TEMPERATURES RISING TO
ABOVE NORMAL VALUES FOR WEDNESDAY NIGHT AND THURSDAY...WITH LOWS IN
THE UPPER 50S AND LOWER 60S AND HIGHS IN THE 70S TO LOWER 80S.
FINALLY FOR WEDNESDAY NIGHT...SINCE THE MODELS CONTINUE TO SHOW THE
POTENTIAL FOR LOW CLOUDS AND FOG...DID UP THE FOG TO AREAS FOR SOME
LOCATIONS IN FAVORED UPSLOPE HIGHER TERRAIN.
PRECIPITATION CHANCES WILL INCREASE HEADING INTO LATE THURSDAY
AFTERNOON AND THURSDAY NIGHT...AS THE UPPER TROUGH PUSHES NORTHEAST
THROUGH THE UPPER GREAT LAKES AND ONTARIO. AN ASSOCIATED LOW
PRESSURE SYSTEM WILL MOVE THROUGH NORTHWEST ONTARIO...BUT IT WILL
PUSH A COLD FRONT EAST ACROSS THE CWA THURSDAY NIGHT INTO FRIDAY
MORNING. ECMWF IS STILL SHOWING THE SLOWEST FRONTAL PASSAGE...WITH
THE PRECIPITATION LINGERING INTO EARLY FRIDAY AFTERNOON AS ANOTHER
WAVE RIDES UP THE FRONT. THERE CONTINUES TO BE SOME MINOR TIMING
DIFFERENCES IN THE COLD FRONT PASSAGE AND SHOWERS...BUT THE GENERAL
IDEA IS SIMILAR WITH MOST LOCATIONS LIKELY TO SEE 0.25-0.5IN OF
RAIN. AS FOR THUNDER...THERE ARE DECENT VARIATIONS IN THE
INSTABILITY...WITH SOME MODELS EVEN SHOWING UP TO 3000 J/KG OF ML
CAPE IF THERE IS ENOUGH CLEARING/HEATING IN THE AFTERNOON. 0-6KM AND
EFFECTIVE SHEAR VALUES STILL LOOK TO BE ON THE MARGINAL SIDE
(25-30KTS) ON THURSDAY AFTERNOON AND THEN INCREASE RIGHT ALONG THE
FRONTAL BOUNDARY. WOULD THINK THE BEST OPPORTUNITY FOR STRONGER
THUNDERSTORMS WOULD BE RIGHT ALONG THE FRONT AS IT MOVES INTO THE
WESTERN CWA LATE THURSDAY AFTERNOON INTO THE EVENING. AT THIS
POINT...THINK BRIEF HEAVY RAIN AND MARGINALLY SEVERE HAIL WOULD BE
THE BIGGEST THREATS IF THE UPDRAFTS CAN BE SUSTAINED.
DRIER AND COOLER AIR WILL MOVE IN RIGHT BEHIND THE FRONT AND SHOULD
LEAD TO A PERIOD OF DRY WEATHER AND EVEN SOME CLEARING FOR A FEW
HOURS. BUT MUCH COLDER AIR...WILL START TO SURGE IN WITH MORE
LOW LEVEL MOISTURE LATER FRIDAY AFTERNOON AND CONTINUE INTO THE
FIRST PART OF SATURDAY. WITH THE FLOW BEING MORE
WEST-NORTHWEST...EXPECT THE MOST CLOUDS TO BE OVER THE NORTH HALF
OF THE CWA AND WITH THE COLDER AIR THERE...EVEN SOME LAKE ENHANCED
CLOUDS (DELTA-T VALUES BETWEEN 10-14) IN THOSE WIND FAVORED AREAS.
WITH THE LATEST TRENDS OF CLOUD DEPTHS BEING 3-4KFT...SHOULD BE
ENOUGH FOR ISOLATED/SCATTERED SHOWERS AND MAY NEED TO ADJUST POPS A
LITTLE HIGHER OVER THE COMING SHIFTS.
THE UPPER TROUGH WILL LIFT NORTHEAST ON SATURDAY NIGHT AND ALLOW
UPPER RIDGING AND HIGH PRESSURE TO BUILD INTO THE AREA FOR SUNDAY.
THUS...EXPECT A DRY SECOND HALF OF THE WEEKEND...ALTHOUGH
TEMPERATURES WON/T WARM UP TOO SIGNIFICANTLY (WITH HIGHS AROUND 60).
ALSO...SATURDAY NIGHT COULD SEE SOME FROST OVER THE INTERIOR WEST
WHERE SKIES BEGIN TO CLEAR AND WINDS LET UP DUE TO THE APPROACHING
HIGH.
THIS HIGH WILL QUICKLY SHIFT EAST-NORTHEAST INTO QUEBEC ON
MONDAY...AS THE AREA IS UNDER THE UPPER RIDGE AXIS. STILL EXPECT
MONDAY TO BE DRY AND MUCH WARMER (HIGHS IN THE MID-UPPER 60S)...BUT
THE NEXT UPPER TROUGH IS LURKING TO THE WEST. THIS UPPER TROUGH
LOOKS TO GIVE A GLANCING BLOW TO THE CWA ON MONDAY NIGHT INTO
TUESDAY AND WILL HIGHLIGHT THE BEST POPS OVER THE NORTHWESTERN HALF
OF THE CWA.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 724 PM EDT TUE SEP 17 2013
EXPECT LLWS AT ALL 3 TAF SITES TNGT WITH NOCTURNAL COOLING CAUSING A
RADIATION INVERSION AND DECOUPLING OF A LIGHTER SFC FLOW FM THE
STRONGER SSW WINDS ABOVE THE INVERSION. LATER TNGT...THIS SSW WIND
WL ADVECT MOISTER AIR AND MVFR/IFR CIGS INTO UPR MI. BEST CHC FOR
THE IFR CONDITIONS WL BE AT IWD ON WED MRNG DOWNWIND OF THE LOWER
CIGS OBSVD UPSTREAM. THESE LOWER CIGS WL PERSIST THRU WED EVEN AS
THE WINDS DIMINISH.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 421 PM EDT TUE SEP 17 2013
BETWEEN HIGH TO THE EAST AND LOW PRES OVER THE PLAINS...SRLY WINDS
WILL REMAIN UP TO 20 KNOTS INTO WED. WINDS SHOULD THEN REMAIN BELOW
20 KNOTS UNTIL LATE THU NIGHT AND FRI WHEN A COLD FRONT MOVES
THROUGH THE REGION AND BRINGS W TO NW WINDS UP TO 30 KNOTS FRI INTO
SAT. WINDS WILL DECREASE BLO 20 KT BY SUNDAY AS HIGH PRESSURE BUILDS
IN FM THE WEST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...SRF
AVIATION...KC
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
107 PM EDT MON SEP 16 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 513 AM EDT MON SEP 16 2013
WV IMAGERY AND RUC ANALYSIS INDICATED NW MID/UPPER LEVEL FLOW
THROUGH THE WESTERN GREAT LAKES BETWEEN A RIDGE OVER THE PLAINS AND A
TROUGH OVER ERN CANADA. STRONG 700-300 MB QVECTOR DIV IN THE WAKE OF
A SHORTWAVE TROUGH MOVING INTO NEW ENGLAND HAS BROUGHT CLEARING SKIES
OVER MOST OF THE REGION AS A 1030 MB SFC HIGH OVER NW ONTARIO AND NRN
MN BUILDS INTO UPPER MI. HOWEVER...LINGERING NE 10 TO 15 KNOT WINDS
OVER ERN LAKE SUPERIOR ALONG WITH 850 MB TEMPS NEAR 0C HAS GENERATED
LAKE CLOUDS THAT HAVE SPREAD INTO PORTIONS OF NRN UPPER MI. THIS
ALONG WITH CONTINUED LIGHT NE WINDS HAVE KEPT TEMPS FROM DROPPING OFF
AS MUCH OVER THE NORTH AND EAST COMPARED TO INLAND LOCATIONS OVER THE
WEST WHERE READINGS INTO THE LOWER 30S WERE COMMON.
TODAY...EXPECT DAYTIME HEATING/MIXING AND CONTINUED DRY ADVECTION TO
HELP SCOUR OUT THE EARLY MORNING CLOUDS WITH MOSTLY SUNNY CONDITIONS
THEN PREVAILING. THE ABUNDANT SUNSHINE WILL HELP PUSH TEMPS TO NEAR
60 THIS AFTERNOON.
TONIGHT...THE SFC HIGH CENTERED JUST EAST OF THE FCST AREA WILL
CONTINUE TO DOMINATE THE REGION WITH A DRY AIRMASS IN PLACE. ANOTHER
NIGHT WITH VERY FAVORABLE RADIATIONAL COOLING CONDITIONS WILL AGAIN
RESULT IN AREAS OF FROST. THE LOWEST READINGS ARE EXPECTED INTO THE
CNTRL AND ERN PORTION OF THE CWA WHERE THE WINDS WILL BE LIGHTEST.
SOME INCREASE IN SRLY WINDS OVER THE FAR WEST AND DOWNSLOPE
LOCATIONS NEAR LAKE SUPERIOR FROM DEVELOPING LAND BREEZE
SHOULD KEEP TEMPS CLOSER TO 40. SINCE THERE IS ALREADY AN ONGOING
FROST ADVISORY...A NEW ONE FOR TONIGHT WAS NOT POSTED AT THIS TIME TO
AVOID CONFUSION EVEN THOUGH ANOTHER ADVISORY FOR TONIGHT WILL LIKELY
BE NEEDED.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 327 AM EDT MON SEP 16 2013
VERY CONVOLUTED FORECAST FOR MID TO LATE WEEK AS MODELS STRUGGLE WITH
AGREEMENT BETWEEN MODELS AND RUN TO RUN CONTINUITY WITH A SYSTEM
PROGGED TO MOVE ACROSS THE NRN CONUS. THE SHORTWAVE THAT THE SYSTEM
WILL EVOLVE FROM IS CURRENTLY ANALYZED BY MODELS TO BE ABOUT 15
DEGREES LONGITUDE WEST OF THE ATLANTIC COAST OF WA/OR...SO THERE ARE
NOT ANY GOOD OBSERVATIONS OF THE MORE SUBTLE SHORTWAVE ENERGY...OR
EVEN THE DEEPER UPPER LOW/TROUGH THAT IT IS ROTATING AROUND. THE
POOR DATA FOR INITIALIZATION EXPLAINS...AT LEAST PARTIALLY...THE
MODEL DISAGREEMENT AND DISCONTINUITY...ESPECIALLY AFTER ADDITIONAL
ENERGY IS ADDED OVER THE NRN PLAINS THAT MAY CAUSE A RAPID DEEPENING
OF THE SYSTEM. THE SYSTEM AND ADDITIONAL SHORTWAVE ENERGY DOES NOT
MOVE FULLY INTO THE UPPER AIR OBSERVATION NETWORK UNTIL LATE
TUE/EARLY WED...SO IMPROVEMENTS TO CONFIDENCE MAY NOT HAPPEN UNTIL
THAT TIME. BASICALLY...THE SYSTEM JUST HAS THE POTENTIAL TO BRING
RAIN...COLDER TEMPS AND WINDS...BUT IT IS THE FIRST OF THE MORE
SIGNIFICANT DEEPER SYSTEMS OF THE SEASON.
BACK TO A MORE ORGANIZED DISCUSSION STARTING AT 12Z TUE...AN UPPER
LEVEL RIDGE WILL BE OVER THE CWA WITH A SHORTWAVE OVER THE CENTRAL
PLAINS. A SFC HIGH WILL BE CENTERED OVER THE LOWER GREAT
LAKES...WITH THE CWA BETWEEN THE HIGH AND A SFC LOW OVER CENTRAL
SASKATCHEWAN. NO PRECIP IS SHOWN BY MODELS TUE AND TUE NIGHT AS THEY
NOW KEEP THE SHORTWAVE WELL S OF THE CWA. WILL LOWER POPS FOR THIS
PERIOD. LOW LEVEL SW FLOW WILL INCREASE TUE AND TUE NIGHT BETWEEN
THE HIGH TO THE E AND LOW TO THE W...WITH INCREASING LOW LEVEL TEMPS
AS WELL.
FOR WED...MODELS HAVE THE AFOREMENTIONED DEEPER LOW PRESSURE SYSTEM
DEEPENING OVER THE DAKOTAS. SOME MODELS ALSO SHOW SHORTWAVE ENERGY
MOVE THROUGH THE CWA WED...AND CAN NOT RULE THIS OUT AT THIS TIME SO
WILL KEEP AT LEAST SLIGHT CHANCE POPS IN THE FORECAST. LOW LEVEL
TEMPS SHOULD INCREASE AGAIN ON WED...BUT HIGH TEMPS SHOULD BE
SIMILAR TO TUE /UPPER 60S TO AROUND 70/ DUE TO INCREASED CLOUD COVER.
WED NIGHT THROUGH SAT AND PARTIALLY INTO SUN IS WHEN MODEL SOLUTIONS
DIVERGE AND CONFIDENCE IS SIGNIFICANTLY REDUCED. MODEL SPREAD
INCLUDES THE 12Z/15 GEM AND 00Z/16 GFS IN BRINGING THE CLOSED OFF
LOW ACROSS ONTARIO TO JAMES BAY BY FRI NIGHT...DRAGGING THE COLD
FRONT ACROSS THE CWA LATE THU UNTIL FRI. THE 12Z/15 ECMWF IS FARTHER
S...DEEPENING THE LOW AS IT MOVES ACROSS THE CWA FRI NIGHT INTO SAT.
THIS REALLY THROWS OFF WINDS...TEMPS AND PRECIP AND OTHER ASSOCIATED
FIELDS. WILL GO WITH A CONSENSUS OF MODEL GUIDANCE AS IT IS
DIFFICULT AND FUTILE TO CHOOSE ANY ONE SOLUTION AT THIS TIME.
MODELS DO COME BACK INTO BETTER AGREEMENT SUN /ESPECIALLY LATER ON
SUN/ WITH BRINGING AN UPPER RIDGE AXIS TO NEAR THE CWA AND A SFC
RIDGE OVER THE CWA BY 00Z MON. AGAIN...WILL STICK WITH A CONSENSUS
OF GUIDANCE FOR THIS PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 107 PM EDT MON SEP 16 2013
LAKE EFFECT CLOUDS WILL CONTINUE TO DISSIPATE THIS AFTERNOON AS
DRIER AIR CONTINUES TO MOVE IN AND TEMPERATURES WARM. VFR CONDITIONS
ARE EXPECTED THROUGH THE FCST PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 513 AM EDT MON SEP 16 2013
WITH SFC HIGH PRES BUILD INTO THE AREA TODAY AND LINGERING INTO
TONIGHT...WINDS WILL REMAIN AT OR BELOW 15 KNOTS. AS THE HIGH SHIFTS
TO THE EAST...SRLY WINDS UP TO 20 KNOTS ARE EXPECTED FROM TUE INTO
WED. WINDS SHOULD THEN REMAIN BELOW 20 KNOTS UNTIL FRI WHEN A TROUGH
MOVING THROUGH THE REGION BRINGS SW TO W WINDS TO AROUND 25 KNOTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...TITUS
AVIATION...07
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
737 AM EDT MON SEP 16 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 513 AM EDT MON SEP 16 2013
WV IMAGERY AND RUC ANALYSIS INDICATED NW MID/UPPER LEVEL FLOW
THROUGH THE WESTERN GREAT LAKES BETWEEN A RIDGE OVER THE PLAINS AND A
TROUGH OVER ERN CANADA. STRONG 700-300 MB QVECTOR DIV IN THE WAKE OF
A SHORTWAVE TROUGH MOVING INTO NEW ENGLAND HAS BROUGHT CLEARING SKIES
OVER MOST OF THE REGION AS A 1030 MB SFC HIGH OVER NW ONTARIO AND NRN
MN BUILDS INTO UPPER MI. HOWEVER...LINGERING NE 10 TO 15 KNOT WINDS
OVER ERN LAKE SUPERIOR ALONG WITH 850 MB TEMPS NEAR 0C HAS GENERATED
LAKE CLOUDS THAT HAVE SPREAD INTO PORTIONS OF NRN UPPER MI. THIS
ALONG WITH CONTINUED LIGHT NE WINDS HAVE KEPT TEMPS FROM DROPPING OFF
AS MUCH OVER THE NORTH AND EAST COMPARED TO INLAND LOCATIONS OVER THE
WEST WHERE READINGS INTO THE LOWER 30S WERE COMMON.
TODAY...EXPECT DAYTIME HEATING/MIXING AND CONTINUED DRY ADVECTION TO
HELP SCOUR OUT THE EARLY MORNING CLOUDS WITH MOSTLY SUNNY CONDITIONS
THEN PREVAILING. THE ABUNDANT SUNSHINE WILL HELP PUSH TEMPS TO NEAR
60 THIS AFTERNOON.
TONIGHT...THE SFC HIGH CENTERED JUST EAST OF THE FCST AREA WILL
CONTINUE TO DOMINATE THE REGION WITH A DRY AIRMASS IN PLACE. ANOTHER
NIGHT WITH VERY FAVORABLE RADIATIONAL COOLING CONDITIONS WILL AGAIN
RESULT IN AREAS OF FROST. THE LOWEST READINGS ARE EXPECTED INTO THE
CNTRL AND ERN PORTION OF THE CWA WHERE THE WINDS WILL BE LIGHTEST.
SOME INCREASE IN SRLY WINDS OVER THE FAR WEST AND DOWNSLOPE
LOCATIONS NEAR LAKE SUPERIOR FROM DEVELOPING LAND BREEZE
SHOULD KEEP TEMPS CLOSER TO 40. SINCE THERE IS ALREADY AN ONGOING
FROST ADVISORY...A NEW ONE FOR TONIGHT WAS NOT POSTED AT THIS TIME TO
AVOID CONFUSION EVEN THOUGH ANOTHER ADVISORY FOR TONIGHT WILL LIKELY
BE NEEDED.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 327 AM EDT MON SEP 16 2013
VERY CONVOLUTED FORECAST FOR MID TO LATE WEEK AS MODELS STRUGGLE WITH
AGREEMENT BETWEEN MODELS AND RUN TO RUN CONTINUITY WITH A SYSTEM
PROGGED TO MOVE ACROSS THE NRN CONUS. THE SHORTWAVE THAT THE SYSTEM
WILL EVOLVE FROM IS CURRENTLY ANALYZED BY MODELS TO BE ABOUT 15
DEGREES LONGITUDE WEST OF THE ATLANTIC COAST OF WA/OR...SO THERE ARE
NOT ANY GOOD OBSERVATIONS OF THE MORE SUBTLE SHORTWAVE ENERGY...OR
EVEN THE DEEPER UPPER LOW/TROUGH THAT IT IS ROTATING AROUND. THE
POOR DATA FOR INITIALIZATION EXPLAINS...AT LEAST PARTIALLY...THE
MODEL DISAGREEMENT AND DISCONTINUITY...ESPECIALLY AFTER ADDITIONAL
ENERGY IS ADDED OVER THE NRN PLAINS THAT MAY CAUSE A RAPID DEEPENING
OF THE SYSTEM. THE SYSTEM AND ADDITIONAL SHORTWAVE ENERGY DOES NOT
MOVE FULLY INTO THE UPPER AIR OBSERVATION NETWORK UNTIL LATE
TUE/EARLY WED...SO IMPROVEMENTS TO CONFIDENCE MAY NOT HAPPEN UNTIL
THAT TIME. BASICALLY...THE SYSTEM JUST HAS THE POTENTIAL TO BRING
RAIN...COLDER TEMPS AND WINDS...BUT IT IS THE FIRST OF THE MORE
SIGNIFICANT DEEPER SYSTEMS OF THE SEASON.
BACK TO A MORE ORGANIZED DISCUSSION STARTING AT 12Z TUE...AN UPPER
LEVEL RIDGE WILL BE OVER THE CWA WITH A SHORTWAVE OVER THE CENTRAL
PLAINS. A SFC HIGH WILL BE CENTERED OVER THE LOWER GREAT
LAKES...WITH THE CWA BETWEEN THE HIGH AND A SFC LOW OVER CENTRAL
SASKATCHEWAN. NO PRECIP IS SHOWN BY MODELS TUE AND TUE NIGHT AS THEY
NOW KEEP THE SHORTWAVE WELL S OF THE CWA. WILL LOWER POPS FOR THIS
PERIOD. LOW LEVEL SW FLOW WILL INCREASE TUE AND TUE NIGHT BETWEEN
THE HIGH TO THE E AND LOW TO THE W...WITH INCREASING LOW LEVEL TEMPS
AS WELL.
FOR WED...MODELS HAVE THE AFOREMENTIONED DEEPER LOW PRESSURE SYSTEM
DEEPENING OVER THE DAKOTAS. SOME MODELS ALSO SHOW SHORTWAVE ENERGY
MOVE THROUGH THE CWA WED...AND CAN NOT RULE THIS OUT AT THIS TIME SO
WILL KEEP AT LEAST SLIGHT CHANCE POPS IN THE FORECAST. LOW LEVEL
TEMPS SHOULD INCREASE AGAIN ON WED...BUT HIGH TEMPS SHOULD BE
SIMILAR TO TUE /UPPER 60S TO AROUND 70/ DUE TO INCREASED CLOUD COVER.
WED NIGHT THROUGH SAT AND PARTIALLY INTO SUN IS WHEN MODEL SOLUTIONS
DIVERGE AND CONFIDENCE IS SIGNIFICANTLY REDUCED. MODEL SPREAD
INCLUDES THE 12Z/15 GEM AND 00Z/16 GFS IN BRINGING THE CLOSED OFF
LOW ACROSS ONTARIO TO JAMES BAY BY FRI NIGHT...DRAGGING THE COLD
FRONT ACROSS THE CWA LATE THU UNTIL FRI. THE 12Z/15 ECMWF IS FARTHER
S...DEEPENING THE LOW AS IT MOVES ACROSS THE CWA FRI NIGHT INTO SAT.
THIS REALLY THROWS OFF WINDS...TEMPS AND PRECIP AND OTHER ASSOCIATED
FIELDS. WILL GO WITH A CONSENSUS OF MODEL GUIDANCE AS IT IS
DIFFICULT AND FUTILE TO CHOOSE ANY ONE SOLUTION AT THIS TIME.
MODELS DO COME BACK INTO BETTER AGREEMENT SUN /ESPECIALLY LATER ON
SUN/ WITH BRINGING AN UPPER RIDGE AXIS TO NEAR THE CWA AND A SFC
RIDGE OVER THE CWA BY 00Z MON. AGAIN...WILL STICK WITH A CONSENSUS
OF GUIDANCE FOR THIS PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 736 AM EDT MON SEP 16 2013
SCT-BKN NE FLOW LAKE CLOUDS JUST ABOVE 3K FT WILL BE POSSIBLE
EARLY AT SAW TIL DAYTIME MIXING INCREASES. OTHERWISE...WITH HIGH
PRES BUILDING INTO THE REGION...VFR CONDITIONS ARE EXPECTED THROUGH
THE FCST PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 513 AM EDT MON SEP 16 2013
WITH SFC HIGH PRES BUILD INTO THE AREA TODAY AND LINGERING INTO
TONIGHT...WINDS WILL REMAIN AT OR BELOW 15 KNOTS. AS THE HIGH SHIFTS
TO THE EAST...SRLY WINDS UP TO 20 KNOTS ARE EXPECTED FROM TUE INTO
WED. WINDS SHOULD THEN REMAIN BELOW 20 KNOTS UNTIL FRI WHEN A TROUGH
MOVING THROUGH THE REGION BRINGS SW TO W WINDS TO AROUND 25 KNOTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
FROST ADVISORY UNTIL 9 AM EDT /8 AM CDT/ THIS MORNING FOR
MIZ002>005-009>011-084.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...TITUS
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
515 AM EDT MON SEP 16 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 513 AM EDT MON SEP 16 2013
WV IMAGERY AND RUC ANALYSIS INDICATED NW MID/UPPER LEVEL FLOW
THROUGH THE WESTERN GREAT LAKES BETWEEN A RIDGE OVER THE PLAINS AND A
TROUGH OVER ERN CANADA. STRONG 700-300 MB QVECTOR DIV IN THE WAKE OF
A SHORTWAVE TROUGH MOVING INTO NEW ENGLAND HAS BROUGHT CLEARING SKIES
OVER MOST OF THE REGION AS A 1030 MB SFC HIGH OVER NW ONTARIO AND NRN
MN BUILDS INTO UPPER MI. HOWEVER...LINGERING NE 10 TO 15 KNOT WINDS
OVER ERN LAKE SUPERIOR ALONG WITH 850 MB TEMPS NEAR 0C HAS GENERATED
LAKE CLOUDS THAT HAVE SPREAD INTO PORTIONS OF NRN UPPER MI. THIS
ALONG WITH CONTINUED LIGHT NE WINDS HAVE KEPT TEMPS FROM DROPPING OFF
AS MUCH OVER THE NORTH AND EAST COMPARED TO INLAND LOCATIONS OVER THE
WEST WHERE READINGS INTO THE LOWER 30S WERE COMMON.
TODAY...EXPECT DAYTIME HEATING/MIXING AND CONTINUED DRY ADVECTION TO
HELP SCOUR OUT THE EARLY MORNING CLOUDS WITH MOSTLY SUNNY CONDITIONS
THEN PREVAILING. THE ABUNDANT SUNSHINE WILL HELP PUSH TEMPS TO NEAR
60 THIS AFTERNOON.
TONIGHT...THE SFC HIGH CENTERED JUST EAST OF THE FCST AREA WILL
CONTINUE TO DOMINATE THE REGION WITH A DRY AIRMASS IN PLACE. ANOTHER
NIGHT WITH VERY FAVORABLE RADIATIONAL COOLING CONDITIONS WILL AGAIN
RESULT IN AREAS OF FROST. THE LOWEST READINGS ARE EXPECTED INTO THE
CNTRL AND ERN PORTION OF THE CWA WHERE THE WINDS WILL BE LIGHTEST.
SOME INCREASE IN SRLY WINDS OVER THE FAR WEST AND DOWNSLOPE
LOCATIONS NEAR LAKE SUPERIOR FROM DEVELOPING LAND BREEZE
SHOULD KEEP TEMPS CLOSER TO 40. SINCE THERE IS ALREADY AN ONGOING
FROST ADVISORY...A NEW ONE FOR TONIGHT WAS NOT POSTED AT THIS TIME TO
AVOID CONFUSION EVEN THOUGH ANOTHER ADVISORY FOR TONIGHT WILL LIKELY
BE NEEDED.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 327 AM EDT MON SEP 16 2013
VERY CONVOLUTED FORECAST FOR MID TO LATE WEEK AS MODELS STRUGGLE WITH
AGREEMENT BETWEEN MODELS AND RUN TO RUN CONTINUITY WITH A SYSTEM
PROGGED TO MOVE ACROSS THE NRN CONUS. THE SHORTWAVE THAT THE SYSTEM
WILL EVOLVE FROM IS CURRENTLY ANALYZED BY MODELS TO BE ABOUT 15
DEGREES LONGITUDE WEST OF THE ATLANTIC COAST OF WA/OR...SO THERE ARE
NOT ANY GOOD OBSERVATIONS OF THE MORE SUBTLE SHORTWAVE ENERGY...OR
EVEN THE DEEPER UPPER LOW/TROUGH THAT IT IS ROTATING AROUND. THE
POOR DATA FOR INITIALIZATION EXPLAINS...AT LEAST PARTIALLY...THE
MODEL DISAGREEMENT AND DISCONTINUITY...ESPECIALLY AFTER ADDITIONAL
ENERGY IS ADDED OVER THE NRN PLAINS THAT MAY CAUSE A RAPID DEEPENING
OF THE SYSTEM. THE SYSTEM AND ADDITIONAL SHORTWAVE ENERGY DOES NOT
MOVE FULLY INTO THE UPPER AIR OBSERVATION NETWORK UNTIL LATE
TUE/EARLY WED...SO IMPROVEMENTS TO CONFIDENCE MAY NOT HAPPEN UNTIL
THAT TIME. BASICALLY...THE SYSTEM JUST HAS THE POTENTIAL TO BRING
RAIN...COLDER TEMPS AND WINDS...BUT IT IS THE FIRST OF THE MORE
SIGNIFICANT DEEPER SYSTEMS OF THE SEASON.
BACK TO A MORE ORGANIZED DISCUSSION STARTING AT 12Z TUE...AN UPPER
LEVEL RIDGE WILL BE OVER THE CWA WITH A SHORTWAVE OVER THE CENTRAL
PLAINS. A SFC HIGH WILL BE CENTERED OVER THE LOWER GREAT
LAKES...WITH THE CWA BETWEEN THE HIGH AND A SFC LOW OVER CENTRAL
SASKATCHEWAN. NO PRECIP IS SHOWN BY MODELS TUE AND TUE NIGHT AS THEY
NOW KEEP THE SHORTWAVE WELL S OF THE CWA. WILL LOWER POPS FOR THIS
PERIOD. LOW LEVEL SW FLOW WILL INCREASE TUE AND TUE NIGHT BETWEEN
THE HIGH TO THE E AND LOW TO THE W...WITH INCREASING LOW LEVEL TEMPS
AS WELL.
FOR WED...MODELS HAVE THE AFOREMENTIONED DEEPER LOW PRESSURE SYSTEM
DEEPENING OVER THE DAKOTAS. SOME MODELS ALSO SHOW SHORTWAVE ENERGY
MOVE THROUGH THE CWA WED...AND CAN NOT RULE THIS OUT AT THIS TIME SO
WILL KEEP AT LEAST SLIGHT CHANCE POPS IN THE FORECAST. LOW LEVEL
TEMPS SHOULD INCREASE AGAIN ON WED...BUT HIGH TEMPS SHOULD BE
SIMILAR TO TUE /UPPER 60S TO AROUND 70/ DUE TO INCREASED CLOUD COVER.
WED NIGHT THROUGH SAT AND PARTIALLY INTO SUN IS WHEN MODEL SOLUTIONS
DIVERGE AND CONFIDENCE IS SIGNIFICANTLY REDUCED. MODEL SPREAD
INCLUDES THE 12Z/15 GEM AND 00Z/16 GFS IN BRINGING THE CLOSED OFF
LOW ACROSS ONTARIO TO JAMES BAY BY FRI NIGHT...DRAGGING THE COLD
FRONT ACROSS THE CWA LATE THU UNTIL FRI. THE 12Z/15 ECMWF IS FARTHER
S...DEEPENING THE LOW AS IT MOVES ACROSS THE CWA FRI NIGHT INTO SAT.
THIS REALLY THROWS OFF WINDS...TEMPS AND PRECIP AND OTHER ASSOCIATED
FIELDS. WILL GO WITH A CONSENSUS OF MODEL GUIDANCE AS IT IS
DIFFICULT AND FUTILE TO CHOOSE ANY ONE SOLUTION AT THIS TIME.
MODELS DO COME BACK INTO BETTER AGREEMENT SUN /ESPECIALLY LATER ON
SUN/ WITH BRINGING AN UPPER RIDGE AXIS TO NEAR THE CWA AND A SFC
RIDGE OVER THE CWA BY 00Z MON. AGAIN...WILL STICK WITH A CONSENSUS
OF GUIDANCE FOR THIS PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 132 AM EDT MON SEP 16 2013
EXCEPT FOR SOME SHALLOW GROUND FOG AT IWD AT TIMES EARLY THIS
MRNG...VFR CONDITIONS WL BE THE RULE AT CMX/IWD THIS FCST PERIOD
WITH INCOMING SFC HI PRES/DRY AIRMASS. AT SAW...A PERSISTENT NNE
UPSLOPE FLOW WITHIN THE LLVL THERMAL TROF FARTHER E OF THE HI CENTER
WL RESULT IN SOME LK EFFECT SC/MVFR CIGS THRU THIS MRNG BEFORE
DAYTIME HEATING MIXES OUT THIS LO CLD. VFR CONDITIONS WL THEN
PREVAIL AT SAW THRU THE REST OF THE PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 513 AM EDT MON SEP 16 2013
WITH SFC HIGH PRES BUILD INTO THE AREA TODAY AND LINGERING INTO
TONIGHT...WINDS WILL REMAIN AT OR BELOW 15 KNOTS. AS THE HIGH SHIFTS
TO THE EAST...SRLY WINDS UP TO 20 KNOTS ARE EXPECTED FROM TUE INTO
WED. WINDS SHOULD THEN REMAIN BELOW 20 KNOTS UNTIL FRI WHEN A TROUGH
MOVING THROUGH THE REGION BRINGS SW TO W WINDS TO AROUND 25 KNOTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
FROST ADVISORY UNTIL 9 AM EDT /8 AM CDT/ THIS MORNING FOR
MIZ002>005-009>011-084.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...TITUS
AVIATION...KC
MARINE...JLB
AREA FORECAST DISCUSSION
NWS DULUTH MN
645 PM CDT TUE SEP 17 2013
.UPDATE...
ISSUED AT 645 PM CDT TUE SEP 17 2013
HAVE UPDATED SKY CONDITIONS FOR A MORE OVERCAST OVERNIGHT
FORECAST...AND A DELAY IN CLEARING FOR WEDNESDAY MORNING.
OTHERWISE LITTLE/NO CHANGE TO CURRENT FORECAST.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 318 PM CDT TUE SEP 17 2013
MOISTURE CONTINUED TO INCREASE FROM WEST TO EAST ACROSS THE
NORTHLAND TODAY. THE HIGH TO THE EAST WAS LOSING IT`S GRIP ON THE
NORTHLAND. A SHORTWAVE WAS MOVING NORTHEAST OUT OF IOWA AND WILL
COMBINE WITH WAA/MOISTURE ADVECTION TO CAUSE CLOUDS TO THICKEN ALL
AREAS TONIGHT AND BRING A CHANCE FOR RAIN. THE RAP WAS DOING A
GOOD JOB DEPICTING THE CLOUDS OVER OUR WESTERN CWA AND THEY SHOW
INCREASING HUMIDITY ACROSS MUCH OF THE AREA BY 06Z. RAIN WILL BE
POSSIBLE TONIGHT...AND WE INCREASED POPS OVER OUR FAR SOUTHERN CWA
WHICH WILL HAVE THE BEST CHANCE AT SEEING UP TO A TENTH OF AN INCH
OVERNIGHT. PWAT VALUES ARE EXPECTED TO RISE TO 1 TO 1.4 INCHES
OVERNIGHT...AND WE EXPECT AREAS OF FOG TO FORM. MOST AREAS SHOULD
NOT EXPERIENCE DENSE FOG...WITH THE EXCEPTION OF AREAS AROUND LAKE
SUPERIOR LATE TONIGHT WHICH COULD SEE SOME PATCHY DENSE FOG. SURFACE
DEWPOINTS ARE EXPECTED TO RISE INTO THE FIFTIES...AND WERE ALREADY
50 TO 55 FROM KINL TO KGPZ TO KAIT AND POINTS WEST. WE KEPT THE
MENTION OF DRIZZLE TONIGHT FOR MOST AREAS...ALTHOUGH WE DON`T
THINK IT WILL BE WIDESPREAD GIVEN UPSTREAM CONDITIONS. AREAS
AROUND THE LAKE WILL HAVE A BETTER CHANCE AND IT COULD BE
WIDESPREAD LATE TONIGHT INTO WEDNESDAY MORNING.
STABILITY GRADUALLY LOWERS TONIGHT...AND WE ADDED A SLIGHT CHANCE
FOR A THUNDERSTORM ACROSS THE SOUTH LATE. WAA WILL CONTINUE
WEDNESDAY...WITH A SHORTWAVE RIDGE ALOFT MOVING THROUGH EARLY.
WE HAVE A CHANCE FOR MORE SHOWERS/STORMS OVER ALL BUT FAR
NORTHWEST AREAS ON WEDNESDAY...WITH THE BEST CHANCE OCCURRING
EARLY. CLOUDS WILL SLOWLY DIMINISH OVER WESTERN AREAS...BUT
SHOULD REMAIN THROUGH MOST OF THE DAY AROUND LAKE SUPERIOR AND
OVER NORTHWEST WISCONSIN. HIGHS WILL RANGE FROM THE MID SIXTIES TO
MID SEVENTIES ACROSS THE NORTHLAND...WARMEST SOUTHWEST...COOLEST
AROUND LAKE SUPERIOR.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 318 PM CDT TUE SEP 17 2013
THE FIRST FEW DAYS OF THIS PERIOD WILL BE STORMY AND WET THEN BECOME
CHILLY WITH A STRONG COLD FRONTAL PASSAGE.
STRONG WAA THAT WILL BE ONGOING AHEAD OF AN APPROACHING COLD FRONT
WILL CONTINUE CLOUDS WEDNESDAY NIGHT. KEPT IN CHANCE OF SHOWERS
AND THUNDERSTORMS WEDNESDAY NIGHT...BUT VERY WARM MID LEVEL TEMPS
MAY PROHIBIT STORM FORMATION. BOTH THE NAM AND GFS SHOW SURGE OF 7H
10+C TEMPS. MUCH BETTER CHANCE OF THUNDERSTORMS WILL BE THURSDAY AS
A STRONG COLD FRONT APPROACHES THE AREA FROM THE WEST. THE NAM MAY BE
A BIT FASTER...BUT THE MODELS ARE IN PRETTY GOOD AGREEMENT WITH
MOVEMENT OF THE FRONT AND RESULTING QPF. DURING THE DAY THE
ATMOSPHERE DESTABILIZES IN THE STRONG WAA REGIME AND WILL BE PRIMED
FOR STORMS WHEN THE FRONT ARRIVES IN THE AFTERNOON/EARLY EVENING
EVENING. LIL`S FORECAST DOWN TO -6 AND MUCAPES UP TO 2500 J/KG. AN
EXTRA BOOST OF LIFT WILL BE PROVIDED BY AN UPPER LEVEL JET AND
S/WV.
STRONG COLD AIR WILL STREAM INTO THE REGION BEHIND THE FRONT FOR THE
FRIDAY...BUT AS HIGH PRESSURE BUILDS INTO THE REGION THE WEEKEND
WILL HAVE SUNSHINE BUT COOLER TEMPS. THIS WILL BE FOLLOWED BY
ANOTHER LOW PRESSURE/COLD FRONT ON FROM EARLY THROUGH MID WEEK WITH
A STRONG UPPER LEVEL TROF/CLOSED LOW.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 645 PM CDT TUE SEP 17 2013
LOW CLOUDS TO OVERSPREAD ALL THE TERMINALS THIS EVENING...WITH
CIGS AT ALL SITES FALLING INTO THE 15-25HFT RANGE BY LATE EVENING.
SCATTERED SHOWERS TO ALSO MOVE IN...WITH KHYR AND KBRD AT GREATEST
RISK OF RAIN WITH IFR CIGS AND MVFR VSBYS IN LIGHT RAIN FOR
SEVERAL HOURS GENERALLY BETWEEN 07Z AND 14Z. RAIN SHOULD END AFTER
THAT...BUT CIGS REMAIN IFR AND VSBYS MVFR FOR A FEW MORE HOURS.
SOME IMPROVEMENT TO BE SEEN AFTER 18Z...BUT LOCAL EFFECTS MAY KEEP
CIGS LOWER WELL INTO THE AFTERNOON.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 53 65 62 74 / 20 20 50 70
INL 54 74 60 71 / 10 10 50 60
BRD 58 77 65 74 / 20 20 50 60
HYR 54 73 62 76 / 40 40 40 70
ASX 54 71 59 78 / 30 30 40 70
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
UPDATE...LE
SHORT TERM...MELDE
LONG TERM...CLC
AVIATION...LE
AREA FORECAST DISCUSSION
NWS GLASGOW MT
305 PM MDT MON SEP 16 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH WEDNESDAY...
QUIET EVENING EXPECTED WITH NORTHEAST MONTANA UNDER SOUTHWEST FLOW
ALOFT. HRRR HAS BEEN HINTING AT SOME SHOWER/THUNDERSTORM ACTIVITY
ENTERING WESTERN ZONES AND THIS HAS SUPPORT FROM THE LATEST NAM
AND GFS SOLUTIONS...ALTHOUGH ECMWF MAINTAINS DRY CONDITIONS. WILL
INCLUDE ISOLATED SHOWERS AND THUNDERSTORMS MAINLY FOR PETROLEUM
AND PHILLIPS COUNTIES. CANNOT RULE OUT POSSIBILITY INTO CENTRAL
PORTIONS OF THE CWA SO EXTENDED POPS A BIT FURTHER
EAST...HOWEVER...CONFIDENCE IS LOW. WILL EXPECT LITTLE MORE THAN
LEFTOVER CLOUD DEBRIS ACROSS MOST OF THE CWA OVERNIGHT IN THE FORM
OF HIGH CIRRUS. EXPECTING 850MB TEMPERATURES TO CONTINUE TO WARM
OVERNIGHT AND SO EXPECT MILDER LOWS TUESDAY MORNING AS COMPARED
WITH THIS MORNING. LASTLY...WILL KEEP AN EYE ON SURFACE WINDS WITH
THE LAKE WIND ADVISORY CONTINUING UNTIL 6PM. MOST MODEL GUIDANCE
INDICATES THAT WINDS WILL BEGIN TO RELAX WITHIN A FEW HOURS BUT
SPEEDS HAVE BEEN SUSTAINED AT OR ABOVE 20 MPH NOW FOR MUCH OF THE
DAY. AN UPDATE WILL BE SENT OUT IN A COUPLE OF HOURS WITH REGARD
TO THE GOING LAKE WIND ADVISORY.
TUESDAY THROUGH THURSDAY...UPPER TROUGH BEGINS TO TRANSLATE
EASTWARD ACROSS THE NORTHWEST AS ATTENTION TURNS TOWARD THE LOW
PRESSURE SYSTEM AS IT BEGINS TO AFFECT THE CWA. LATEST GFS AND
ECMWF ADVERTISE A DEEPENING SURFACE LOW WITH 997MB INTENSITY BY
WEDNESDAY AFTERNOON. NICE UPPER LEVEL DYNAMICS WILL COME INTO PLAY
WITH THE LOW PRESSURE SQUARELY WITHIN THE LEFT EXIT REGION OF THE
JET. THIS DEEPENING LOW WILL ALSO SERVE TO SHARPEN THE PRESSURE
GRADIENT ACROSS THE CWA AND SO INCREASED WINDS FOR THE PERIOD.
REGARDING PRECIPITATION CHANCES...CONCERNS SURROUND THE RAINFALL AMOUNT
WITH THIS SYSTEM AS THE TRACK OF THE SURFACE LOW IS STILL SOMEWHAT
UNCERTAIN. THE ECMWF AND GFS SHOW THE CENTER OF THE LOW TRACKING
ACROSS SOUTHEAST MONTANA AND THEN INTO NORTH DAKOTA AND EVENTUALLY
PUSHING INTO SOUTHERN MANITOBA. WOULD LIKE TO SEE THE TRACK A BIT
FURTHER SOUTH TO FEEL CONFIDENT IN WIDESPREAD WETTING RAINS AS
SUCH A TRACK LIKE WHAT IS PRESENTLY EXPECTED WOULD INTRODUCE
CONCERNS FOR A DRY SLOT SHUTTING OFF PRECIPITATION FOR A
TIME...ESPECIALLY ACROSS THE SOUTHERN AND SOUTHEASTERN ZONES NEAR
AND SOUTH OF THE TRACK. FURTHER NORTH NEAR THE INTERNATIONAL
BORDER...CONFIDENCE IS HIGHER ON STEADIER RAIN AND IN FACT
INTRODUCED THAT WORDING INTO THE GRIDS WITH SHOWERS FURTHER SOUTH
WHERE IT WILL BE MORE ISOLATED/SCATTERED IN NATURE.IN THE
STRATIFORM RAIN REGION DO EXPECT POTENTIAL EMBEDDED THUNDER AS
WELL DEPENDING ON MESOSCALE FORCING IN ADDITION TO LOCATION OF
BEST PVA AND UPPER LEVEL DYNAMICS. POSSIBILITY EXISTS IF THE CURRENT
FORECAST TRACK VERIFIES FOR SOME LOCATIONS TO PICK UP A RAINFALL
TOTAL EXCEEDING AN INCH BY THE END OF THE EVENT NEAR THE
INTERNATIONAL BORDER. WHILE STEADIEST RAINFALL WILL LIKELY BE
LOCATED NORTH OF THE MISSOURI RIVER...CANNOT RULE OUT THE
POSSIBILITY THAT FUTURE MODEL RUNS WILL SHIFT THE STORM TRACK
FURTHER SOUTH WHICH WOULD RESULT IN MORE WIDESPREAD WETTING RAINS.
LIKEWISE...SHOULD THE STORM TRACK FURTHER TO THE NORTH PER LATEST
NAM SOLUTION...MOST OF THE RAINFALL WOULD BE CONFINED TO SOUTHERN
SASKATCHEWAN AND MANITOBA...LEAVING THE CWA MAINLY DRY. NAM LOOKS
TO BE AN OUTLIER SOLUTION HOWEVER SO FOR NOW WILL DISREGARD THAT
SCENARIO. THE GOING FORECAST WILL LEAN TOWARD THE ECMWF/GFS/SREF
SOLUTIONS WITH GOOD CONSENSUS BEING SHOWN IN THE MODELS AND
CURRENT GRIDS NOW REFLECT LATEST THINKING. MALIAWCO
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...
GOING FORECAST LOOKED GOOD BUT TO HELP WITH CONSISTENCY...ENDED
PRECIPITATION A BIT QUICKER THURSDAY. MODELS WERE HINTING AT
SLIGHTLY WARMER TEMPS ON THURSDAY AS WELL..SO RAISED THEM A COUPLE
DEGREES MOST PLACES.
LATE IN THE PERIOD...MODELS CONTINUE TO DISAGREE ABOUT SHOWERS
THAT FALL OUT FROM AN UPPER TROUGH. HAVE LEFT THIS PERIOD ALONE.
TFJ
PREVIOUS DISCUSSION...
THE EXTENDED BEGINS WITH AN ONGOING SYSTEM OVER THE NORTHERN
PLAINS AND CANADIAN PRAIRIES. THE MODELS ARE SIMILAR ON THE MAIN
FEATURES ON HOW THE SYSTEM DEVELOPS AND MOVES...HOWEVER
POSITIONING IS THE MAIN DIFFERENCE THROUGH THE PERIOD. WILL
CONTINUE TO SIDE WITH THE ECMWF FOR THE FORECAST TO FIT THE
FORECAST TREND.
THE EC/GEM ARE THE FASTEST ON GETTING THE PRECIP OUT OF THE AREA
ON THURSDAY WHERE THE GFS LINGERS...WILL RESPECT THE GFS ENOUGH
FOR LOW POPS THURSDAY.
FRIDAY THROUGH SATURDAY NIGHT HAS ANOTHER RIDGE AND FAIR WEATHER
FOR THE REGION.
SATURDAY NIGHT THROUGH MONDAY ANOTHER UPPER LEVEL SYSTEM MOVES
THROUGH THE REGION. THE MODELS HAVE THE SIMILAR IDEA THAT A SYSTEM
WILL MOVE THROUGH THE PLAINS OR PRAIRIES...HOWEVER LOCATION OF THE
SYSTEM IS DIFFERENT IN EACH MODEL TO PROVIDE INCREASE CONFIDENCE
AT THIS TIME TO INCREASE PRECIPITATION CHANCES. PROTON
&&
.AVIATION...
FLIGHT CATEGORY: VFR.
A CLUSTER OF THUNDERSTORMS NEAR BOZEMAN DURING THE MID AFTERNOON
WILL CONTINUE MOVING NORTHEAST...POSSIBLY REACHING THE GLASGOW
AREA LATER THIS EVENING BEFORE THEY FALL APART. SHOWERS/THUNDERSTORMS
ARE NOT EXPECTED EAST OF A GLASGOW TO JORDAN LINE. CLEARING SKIES
WILL OCCUR IN THE WAKE OF TONIGHT/S WEATHER BUT ANOTHER ROUND OF
SHOWERS/ISOLATED STORMS WILL MOVE IN LATE TUESDAY.
SOUTHEAST WINDS WILL DIMINISH BY EARLY EVENING WITH LIGHT AND
VARIABLE WINDS LATE TONIGHT AND TUESDAY. TFJ
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 6 PM MDT THIS EVENING FOR FORT PECK
LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...GARFIELD...MCCONE...PETROLEUM.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1043 PM CDT TUE SEP 17 2013
.AVIATION...
06Z TAFS FOR KOFK...KOMA AND KLNK
ALTHOUGH LOWER CLOUDS HAD CLEARED KLNK AS OF 03Z...AND THE
CLEARING LINE WAS NEAR KOFK...CLEARING WAS SLOWING AND A BAND OF
MVFR CIGS WERE WORKING N ALONG MO RIVER TOWARD KOMA. CIG FORECAST
TONIGHT WILL CONTINUE TO BE MAIN AVIATION CONCERN...AND THEN
GENERALLY AT KOMA WHERE MVFR CIGS COULD MOVE BACK IN. IN ADDITION
A LITTLE LIGHT FOG/HAZE IS POSSIBLE AT TAF SITES TONIGHT...BUT LOW
LEVEL JET SHOULD KEEP ANY VISIBILITY RESTRICTION ABOVE IFR
CATEGORY AND POSSIBLY EVEN ABOVE 5SM. THIS LOW LEVEL JET COULD
ALSO PROVIDE OCCASIONAL WIND SHEAR CONDITIONS UNTIL THEY MIX OUT
MID WED MORNING...ESPECIALLY WHEN SFC WINDS ARE BACKED AND LESS
THAN 10-12KTS. APPROACHING COLD FRONT WILL REMAIN WEST OF TAF
SITES THROUGH 18/06Z.
CHERMOK
&&
.PREV DISCUSSION... /ISSUED 1004 PM CDT TUE SEP 17 2013/
UPDATE...
SENT AN UPDATE EARLIER IN THE EVENING TO TRIM POPS AND ADJUST
CLOUDS AND WINDS.
DISCUSSION...
GENERAL FORECAST IN GOOD SHAPE WITH THE LOW LEVEL JET INCREASING
TONIGHT. DEEPER MOISTURE HAS SHIFTED OUT OF THE AREA...HOWEVER PER
OAX SOUNDING...STILL DECENT MOISTURE BELOW 800MB. CONTINUED TO
TRIM POPS TO FAR NORTHEAST AS THE LOW LEVEL JET INCREASES AND
MOISTURE GETS PUSHED FARTHER EAST. SOUTHEAST WINDS SHOULD HELP
KEEP TEMPERATURES FROM BOTTOMING OUT AND SOME PATCHY FOG STILL
EXPECTED WITH DEWPOINTS IN THE 60S AND LOWS IN THE 60S.
ZAPOTOCNY
PREV DISCUSSION... /ISSUED 315 PM CDT TUE SEP 17 2013/
SHORT TERM CONCERNS ARE MAINLY CLOUD COVER INTO WEDNESDAY MORNING
AND TEMPERATURES THE NEXT FEW DAYS.
12Z UPPER AIR CHARTS SHOWED THE FOLLOWING. AT 300 MB...JETSTREAM
AXIS EXTENDED FROM BASE OF THE TROUGH RIGHT ALONG THE WEST COAST
NORTHEASTWARD ACROSS THE ROCKIES AND INTO MANITOBA. AT 500 MB...ONE
AREA OF GREATER THAN 30 METER HEIGHT FALLS EXTENDED FROM CANADA DOWN
INTO MO. MORE SIGNIFICANT FALLS (60-90 METERS) WERE JUST AHEAD OF
THE TROUGH OVER NORTHERN CA...SOUTHERN OR AND INTO NV. DECENT
MOISTURE WAS NOTED FROM NRN MEXICO UP INTO THE CENTRAL PLAINS AT
AND BELOW 700 MB. EARLY AFTN WATER VAPOR IMAGERY SHOWED DRYING
MOVING ACROSS THE PLAINS BETWEEN THE TWO SHORTWAVES. EARLY AFTN
SURFACE ANALYSIS SHOWED MODEST SOUTHERLY FLOW IN PLACE OVER THE
AREA WITH DEWPOINTS IN THE 50S AND 60S.
TONIGHT...EXPECT SOME DECREASE IN OVERALL CLOUD COVER. FORECAST
SOUNDINGS SHOW SOME ELEVATED INSTABILITY THIS EVENING ALONG WITH
DECENT MID LEVEL LAPSE RATES. LATEST RUNS OF THE RAP DEVELOP SOME
PCPN ACROSS ABOUT THE EASTERN 1/2 OF MY AREA. 12Z GFS DID TOO.
SO WILL INCLUDE A SMALL CHANCE FOR TSTMS PRIOR TO 09Z. WITH
SUBSTANTIAL LOW LEVEL MOISTURE REMAINING IN PLACE AFTER HIGHER
CLOUDS CLEAR OUT...HAVE SOME CONCERN THAT STRATUS MAY REFORM. WE
MAY ALSO HAVE SOME FOG BUT IT APPEARS TO BE LESS OF A CONCERN FOR
THE PUBLIC FORECAST DUE TO WINDS MOSTLY ABOVE 7 KNOTS.
WEDNESDAY...SOUTHERLY FLOW WILL INCREASE AS MIXING DEPTH INCREASES
THROUGH THE MORNING...WITH BREEZY/WINDY CONDITIONS BY AFTN. 850 MB
TEMPERATURES WILL INCREASE SUBSTANTIALLY COMPARED TO TODAY (INTO THE
19-22 DEGREE CELSIUS RANGE BY 00Z THURSDAY)...SO HIGHS IN THE
UPPER 80S TO AROUND 90 SEEM LIKELY.
SYSTEM FOR WEDNESDAY NIGHT INTO THURSDAY SEEMS TO HAVE SLOWED DOWN A
BIT SO DID MAKE SOME ADJUSTMENTS FOR PCPN TIMING IN THOSE PERIODS.
COLD FRONT SHOULD ENTER OUR FAR NORTHWEST COUNTIES BETWEEN 06Z AND
09Z THURSDAY THEN EXIT THE SOUTHEAST COUNTIES BETWEEN 21Z THURSDAY
AND 00Z FRIDAY. BOOSTED PCPN CHANCES A BIT FOR THURSDAY...BUT IT NOW
APPEARS THE SYSTEM WILL EXIT SOONER THURSDAY NIGHT BASED ON A BLEND
OF GFS/NAM/SREF/ECMWF/GEM.
THE PERIOD FROM FRIDAY THROUGH SUNDAY SHOULD BE DRY...WITH HIGHS IN
THE 70S TO AROUND 80. 500 MB TROUGH WILL BE SHIFTING EAST OF THE
AREA FRIDAY...WITH RIDGING OVER THE ROCKIES AND ANOTHER TROUGH OFF
THE WEST COAST. FLOW WILL BE PROGRESSIVE IN THIS PERIOD...WITH THE
NEXT CHANCE OF PCPN MOVING IN BY SUNDAY NIGHT AS THE SYSTEM DIGS
OVER THE ROCKIES. DIFLUENT FLOW ALONG WITH INCREASING MOISTURE
AHEAD OF THE NEXT COLD FRONT SHOULD BRING SOME SHOWERS AND TSTMS
FROM SUNDAY NIGHT THROUGH MONDAY NIGHT.
MILLER
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1004 PM CDT TUE SEP 17 2013
.UPDATE...
SENT AN UPDATE EARLIER IN THE EVENING TO TRIM POPS AND ADJUST
CLOUDS AND WINDS.
&&
.DISCUSSION...
GENERAL FORECAST IN GOOD SHAPE WITH THE LOW LEVEL JET INCREASING
TONIGHT. DEEPER MOISTURE HAS SHIFTED OUT OF THE AREA...HOWEVER PER
OAX SOUNDING...STILL DECENT MOISTURE BELOW 800MB. CONTINUED TO
TRIM POPS TO FAR NORTHEAST AS THE LOW LEVEL JET INCREASES AND
MOISTURE GETS PUSHED FARTHER EAST. SOUTHEAST WINDS SHOULD HELP
KEEP TEMPERATURES FROM BOTTOMING OUT AND SOME PATCHY FOG STILL
EXPECTED WITH DEWPOINTS IN THE 60S AND LOWS IN THE 60S.
.PREV DISCUSSION... /ISSUED 611 PM CDT TUE SEP 17 2013/
AVIATION...
00Z TAFS FOR KOFK...KOMA AND KLNK.
LOW CLOUDS CONTINUED TO CLEAR/BREAK UP FROM THE SOUTHWEST AND THIS
TREND IS EXPECTED TO PERSIST THROUGH THE EVENING. HOWEVER...THE
CLEARING COULD SLOW..ESPECIALLY IN NERN NEBR...AND TRENDS WILL BE
MONITORED. OTHERWISE...WITH SURFACE WINDS SOMEWHAT DECREASED AND
BACKED...AN INCREASING SSW LOW LEVEL JET COULD BRING LOW LEVEL
WIND SHEAR CONDITIONS TO TAF SITES TONIGHT BEFORE WINDS MIX OUT
WEDNESDAY MID MORNING.
CHERMOK
PREV DISCUSSION... /ISSUED 315 PM CDT TUE SEP 17 2013/
DISCUSSION...
SHORT TERM CONCERNS ARE MAINLY CLOUD COVER INTO WEDNESDAY MORNING
AND TEMPERATURES THE NEXT FEW DAYS.
12Z UPPER AIR CHARTS SHOWED THE FOLLOWING. AT 300 MB...JETSTREAM
AXIS EXTENDED FROM BASE OF THE TROUGH RIGHT ALONG THE WEST COAST
NORTHEASTWARD ACROSS THE ROCKIES AND INTO MANITOBA. AT 500 MB...ONE
AREA OF GREATER THAN 30 METER HEIGHT FALLS EXTENDED FROM CANADA DOWN
INTO MO. MORE SIGNIFICANT FALLS (60-90 METERS) WERE JUST AHEAD OF
THE TROUGH OVER NORTHERN CA...SOUTHERN OR AND INTO NV. DECENT
MOISTURE WAS NOTED FROM NRN MEXICO UP INTO THE CENTRAL PLAINS AT
AND BELOW 700 MB. EARLY AFTN WATER VAPOR IMAGERY SHOWED DRYING
MOVING ACROSS THE PLAINS BETWEEN THE TWO SHORTWAVES. EARLY AFTN
SURFACE ANALYSIS SHOWED MODEST SOUTHERLY FLOW IN PLACE OVER THE
AREA WITH DEWPOINTS IN THE 50S AND 60S.
TONIGHT...EXPECT SOME DECREASE IN OVERALL CLOUD COVER. FORECAST
SOUNDINGS SHOW SOME ELEVATED INSTABILITY THIS EVENING ALONG WITH
DECENT MID LEVEL LAPSE RATES. LATEST RUNS OF THE RAP DEVELOP SOME
PCPN ACROSS ABOUT THE EASTERN 1/2 OF MY AREA. 12Z GFS DID TOO.
SO WILL INCLUDE A SMALL CHANCE FOR TSTMS PRIOR TO 09Z. WITH
SUBSTANTIAL LOW LEVEL MOISTURE REMAINING IN PLACE AFTER HIGHER
CLOUDS CLEAR OUT...HAVE SOME CONCERN THAT STRATUS MAY REFORM. WE
MAY ALSO HAVE SOME FOG BUT IT APPEARS TO BE LESS OF A CONCERN FOR
THE PUBLIC FORECAST DUE TO WINDS MOSTLY ABOVE 7 KNOTS.
WEDNESDAY...SOUTHERLY FLOW WILL INCREASE AS MIXING DEPTH INCREASES
THROUGH THE MORNING...WITH BREEZY/WINDY CONDITIONS BY AFTN. 850 MB
TEMPERATURES WILL INCREASE SUBSTANTIALLY COMPARED TO TODAY (INTO THE
19-22 DEGREE CELSIUS RANGE BY 00Z THURSDAY)...SO HIGHS IN THE
UPPER 80S TO AROUND 90 SEEM LIKELY.
SYSTEM FOR WEDNESDAY NIGHT INTO THURSDAY SEEMS TO HAVE SLOWED DOWN A
BIT SO DID MAKE SOME ADJUSTMENTS FOR PCPN TIMING IN THOSE PERIODS.
COLD FRONT SHOULD ENTER OUR FAR NORTHWEST COUNTIES BETWEEN 06Z AND
09Z THURSDAY THEN EXIT THE SOUTHEAST COUNTIES BETWEEN 21Z THURSDAY
AND 00Z FRIDAY. BOOSTED PCPN CHANCES A BIT FOR THURSDAY...BUT IT NOW
APPEARS THE SYSTEM WILL EXIT SOONER THURSDAY NIGHT BASED ON A BLEND
OF GFS/NAM/SREF/ECMWF/GEM.
THE PERIOD FROM FRIDAY THROUGH SUNDAY SHOULD BE DRY...WITH HIGHS IN
THE 70S TO AROUND 80. 500 MB TROUGH WILL BE SHIFTING EAST OF THE
AREA FRIDAY...WITH RIDGING OVER THE ROCKIES AND ANOTHER TROUGH OFF
THE WEST COAST. FLOW WILL BE PROGRESSIVE IN THIS PERIOD...WITH THE
NEXT CHANCE OF PCPN MOVING IN BY SUNDAY NIGHT AS THE SYSTEM DIGS
OVER THE ROCKIES. DIFLUENT FLOW ALONG WITH INCREASING MOISTURE
AHEAD OF THE NEXT COLD FRONT SHOULD BRING SOME SHOWERS AND TSTMS
FROM SUNDAY NIGHT THROUGH MONDAY NIGHT.
MILLER
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
ZAPOTOCNY
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
611 PM CDT TUE SEP 17 2013
.AVIATION...
00Z TAFS FOR KOFK...KOMA AND KLNK.
LOW CLOUDS CONTINUED TO CLEAR/BREAK UP FROM THE SOUTHWEST AND THIS
TREND IS EXPECTED TO PERSIST THROUGH THE EVENING. HOWEVER...THE
CLEARING COULD SLOW..ESPECIALLY IN NERN NEBR...AND TRENDS WILL BE
MONITORED. OTHERWISE...WITH SURFACE WINDS SOMEWHAT DECREASED AND
BACKED...AN INCREASING SSW LOW LEVEL JET COULD BRING LOW LEVEL
WIND SHEAR CONDITIONS TO TAF SITES TONIGHT BEFORE WINDS MIX OUT
WEDNESDAY MID MORNING.
CHERMOK
&&
.PREV DISCUSSION... /ISSUED 315 PM CDT TUE SEP 17 2013/
DISCUSSION...
SHORT TERM CONCERNS ARE MAINLY CLOUD COVER INTO WEDNESDAY MORNING
AND TEMPERATURES THE NEXT FEW DAYS.
12Z UPPER AIR CHARTS SHOWED THE FOLLOWING. AT 300 MB...JETSTREAM
AXIS EXTENDED FROM BASE OF THE TROUGH RIGHT ALONG THE WEST COAST
NORTHEASTWARD ACROSS THE ROCKIES AND INTO MANITOBA. AT 500 MB...ONE
AREA OF GREATER THAN 30 METER HEIGHT FALLS EXTENDED FROM CANADA DOWN
INTO MO. MORE SIGNIFICANT FALLS (60-90 METERS) WERE JUST AHEAD OF
THE TROUGH OVER NORTHERN CA...SOUTHERN OR AND INTO NV. DECENT
MOISTURE WAS NOTED FROM NRN MEXICO UP INTO THE CENTRAL PLAINS AT
AND BELOW 700 MB. EARLY AFTN WATER VAPOR IMAGERY SHOWED DRYING
MOVING ACROSS THE PLAINS BETWEEN THE TWO SHORTWAVES. EARLY AFTN
SURFACE ANALYSIS SHOWED MODEST SOUTHERLY FLOW IN PLACE OVER THE
AREA WITH DEWPOINTS IN THE 50S AND 60S.
TONIGHT...EXPECT SOME DECREASE IN OVERALL CLOUD COVER. FORECAST
SOUNDINGS SHOW SOME ELEVATED INSTABILITY THIS EVENING ALONG WITH
DECENT MID LEVEL LAPSE RATES. LATEST RUNS OF THE RAP DEVELOP SOME
PCPN ACROSS ABOUT THE EASTERN 1/2 OF MY AREA. 12Z GFS DID TOO.
SO WILL INCLUDE A SMALL CHANCE FOR TSTMS PRIOR TO 09Z. WITH
SUBSTANTIAL LOW LEVEL MOISTURE REMAINING IN PLACE AFTER HIGHER
CLOUDS CLEAR OUT...HAVE SOME CONCERN THAT STRATUS MAY REFORM. WE
MAY ALSO HAVE SOME FOG BUT IT APPEARS TO BE LESS OF A CONCERN FOR
THE PUBLIC FORECAST DUE TO WINDS MOSTLY ABOVE 7 KNOTS.
WEDNESDAY...SOUTHERLY FLOW WILL INCREASE AS MIXING DEPTH INCREASES
THROUGH THE MORNING...WITH BREEZY/WINDY CONDITIONS BY AFTN. 850 MB
TEMPERATURES WILL INCREASE SUBSTANTIALLY COMPARED TO TODAY (INTO THE
19-22 DEGREE CELSIUS RANGE BY 00Z THURSDAY)...SO HIGHS IN THE
UPPER 80S TO AROUND 90 SEEM LIKELY.
SYSTEM FOR WEDNESDAY NIGHT INTO THURSDAY SEEMS TO HAVE SLOWED DOWN A
BIT SO DID MAKE SOME ADJUSTMENTS FOR PCPN TIMING IN THOSE PERIODS.
COLD FRONT SHOULD ENTER OUR FAR NORTHWEST COUNTIES BETWEEN 06Z AND
09Z THURSDAY THEN EXIT THE SOUTHEAST COUNTIES BETWEEN 21Z THURSDAY
AND 00Z FRIDAY. BOOSTED PCPN CHANCES A BIT FOR THURSDAY...BUT IT NOW
APPEARS THE SYSTEM WILL EXIT SOONER THURSDAY NIGHT BASED ON A BLEND
OF GFS/NAM/SREF/ECMWF/GEM.
THE PERIOD FROM FRIDAY THROUGH SUNDAY SHOULD BE DRY...WITH HIGHS IN
THE 70S TO AROUND 80. 500 MB TROUGH WILL BE SHIFTING EAST OF THE
AREA FRIDAY...WITH RIDGING OVER THE ROCKIES AND ANOTHER TROUGH OFF
THE WEST COAST. FLOW WILL BE PROGRESSIVE IN THIS PERIOD...WITH THE
NEXT CHANCE OF PCPN MOVING IN BY SUNDAY NIGHT AS THE SYSTEM DIGS
OVER THE ROCKIES. DIFLUENT FLOW ALONG WITH INCREASING MOISTURE
AHEAD OF THE NEXT COLD FRONT SHOULD BRING SOME SHOWERS AND TSTMS
FROM SUNDAY NIGHT THROUGH MONDAY NIGHT.
MILLER
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS RALEIGH NC
305 PM EDT MON SEP 16 2013
.SYNOPSIS...
A COLD FRONT TO OUR NORTH WILL PUSH SOUTHWARD THROUGH NORTH CAROLINA
THIS EVENING INTO TONIGHT. CANADIAN HIGH PRESSURE WILL BUILD INTO
THE REGION FROM THE NORTH TUESDAY INTO WEDNESDAY.
&&
.NEAR TERM /TONIGHT AND TUESDAY/...
AS OF 300 PM MONDAY...
THROUGH TONIGHT: THE COLD FRONT CURRENTLY SITS ACROSS WV AND CENTRAL
VA... POISED TO CONTINUE DROPPING SOUTHWARD INTO NC BY EARLY THIS
EVENING THEN TO THE SC STATE LINE SOON AFTER MIDNIGHT... PROPELLED
BY THE DIGGING TROUGH OVER THE FAR NORTHEAST STATES. THE DEEPEST
CONVECTION SO FAR THIS AFTERNOON HAS BEEN CONFINED TO AREAS SOUTH
AND EAST OF THE FORECAST AREA WITHIN THE BETTER LOW LEVEL THETA-E
ADVECTION ZONE AND WHERE INSTABILITY HAS BEEN GREATEST (1000 J/KG OF
MLCAPE... MORE THAN THE EARLY MORNING MODELS SUGGESTED). THIS
MORNING`S HIGH DEW POINTS HAVE MIXED OUT WITH HEATING... WELL DOWN
INTO THE 50S TO LOWER 60S OVER ALL BUT THE FAR SE CWA... SO LATEST
HRRR/RAP MODEL TRENDS OF HOLDING THE MORE SIGNIFICANT INSTABILITY
OVER THE FAR SE CWA FOR THE NEXT SEVERAL HOURS APPEARS REASONABLE.
WITH MOISTENING THROUGH THE COLUMN AND INCREASED PW VALUES JUST
AHEAD OF THE FRONT HOWEVER... STILL EXPECT ISOLATED (AND POSSIBLY
SCATTERED) SHOWERS TO PUSH SOUTHWARD INTO NORTH CENTRAL NC THROUGH
THE REST OF THE AFTERNOON... BEFORE PUSHING INTO CENTRAL AND
SOUTHERN SECTIONS OF THE FORECAST AREA BY LATE THIS EVENING. THE
GOOD INVERTED-V SIGNATURE SEEN ON RAP SOUNDINGS SUGGESTS THAT ANY OF
THESE SHOWERS AND STORMS MAY PRODUCE BRIEF STRONG WIND GUSTS.
WIDESPREAD CLOUDS AND A FEW SHOWERS ARE LIKELY TO LINGER INTO THE
OVERNIGHT HOURS OVER THE SW CWA WITH LOW LEVEL FLOW TAKING ON AN
UPSLOPE COMPONENT AND CONTINUED DECENT LOW LEVEL MOISTURE TRANSPORT.
FOLLOWING TRENDS OF THE HRRR AND LOCAL WRF... AND LOOKING AT
UPSTREAM TEMP TRENDS... EXPECT LOWS TO RANGE FROM 57 NORTH TO 64
SOUTH. WINDS BEHIND THE FRONT ARE LIKELY TO STRENGTHEN TO AROUND 10
KTS WITH GUSTS AS MUCH AS 15-20 KTS... ALTHOUGH CONFIDENCE IS LOW
REGARDING HOW MUCH WE`LL STAY MIXED TONIGHT.
FOR TUESDAY: EXPECT IMPROVING CONDITIONS FROM NNE TO SSW AS COOL
HIGH PRESSURE BUILDS IN. THE FRONT IS EXPECTED TO HANG UP ACROSS SC
AND BACK UP INTO FAR SW NC... AND CLOUDS ACROSS OUR FAR SOUTHERN AND
SW AREAS SHOULD BE SLOWER TO CLEAR OUT WITH FORECAST SOUNDINGS
INDICATING LINGERING MOISTURE AT AROUND 850-800 MB... BENEATH THE
WARM SUBSIDING MID LEVELS. OTHERWISE... BESIDES THE CLOUDS... EXPECT
QUIET AND DRY WEATHER WITH NOTABLY COOLER TEMPS... AS THICKNESSES
DROP OVERNIGHT TO AROUND 1370 M... SUPPORTING HIGHS 73-79. -GIH
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 245 PM MONDAY...
A HIGH PRESSURE RIDGE AXIS AT THE SURFACE AND ALOFT WILL EXTEND
ACROSS CENTRAL NC TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. THE DRY
STABLE AIR ASSOCIATED WITH THIS WEATHER FEATURE WILL RESULT IN CLEAR
TO FAIR SKIES AND TEMPS 3-5 DEGREES BELOW NORMAL ON WEDNESDAY. EARLY
WEDNESDAY MORNING LOW TEMPS WILL TEND TO BE A LITTLE CHILLY. MODEL
LOW LEVEL THICKNESSES WEDNESDAY MORNING HOVERING IN THE UPPER 1350S
TO THE MID 1360S. SUNDAY MORNING THICKNESSES VERIFIED IN THE UPPER
1360S. IF MODEL THICKNESSES VERIFY WEDNESDAY MORNING...MIN TEMPS IN
THE 45-50 DEGREE RANGE ONCE AGAIN HIGHLY PROBABLE IN THE OUTLYING
AREAS WITH LOW-MID 50S COMMON IN THE URBAN LOCATIONS. CAVEAT TO MIN
TEMPS WEDNESDAY MORNING: IF DECK OF STRATOCU DEVELOPS BELOW
SUBSIDENCE INVERSION (GFS EMPHASIZES THIS MORE THAN NAM)...THIS
WOULD SUGGEST MIN TEMPS 3-4 DEGREES WARMER THAN
FORECAST...ESPECIALLY ACROSS THE EAST). A MODIFYING AIR MASS BY
WEDNESDAY NIGHT SUGGEST MIN TEMPS 3-5 DEGREES WARMER COMPARED TO
TUESDAY NIGHT. MIN TEMPS GENERALLY IN THE MID-UPPER 50S.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 250 PM MONDAY...
THURSDAY THROUGH FRIDAY NIGHT...
AIR MASS WILL UNDERGO MODIFICATION THIS PERIOD AS SURFACE HIGH
PRESSURE RIDGE SLOWLY WEAKENS AND DRIFTS EWD. THIS WILL ESTABLISH A
RETURN FLOW REGIME BY FRIDAY AND CONTINUING INTO FRIDAY NIGHT. WHILE
DRY WEATHER SHOULD RULE THROUGH FRIDAY...A STRAY SHOWER POSSIBLE
OVER THE NW PIEDMONT LATE FRIDAY. THICKNESSES RECOVER THURSDAY INTO
FRIDAY...SUPPORTIVE OF TEMPS RETURNING TO NEAR NORMAL VALUES
(UPPER 70S NW TO LOWER 80S SE).
SATURDAY THROUGH MONDAY...
MEDIUM RANGE MODEL GUIDANCE CONTINUES TO SUGGEST THE NEXT S/W IN THE
NORTHERN STREAM WILL AFFECT CENTRAL NC SATURDAY INTO SUNDAY. 12Z GFS
IS A LITTLE MORE VIGOROUS WITH THE S/W COMPARED TO ITS PREVIOUS RUNS
AS WELL AS THE 00Z ECMWF. GFS DEPICTS DEEPER MOISTURE AND MORE
ORGANIZED LIFT THROUGH THE ATMOSPHERE COMPARED TO THE 00Z ECMWF.
UNLIKE THE PREVIOUS TWO SYSTEMS IN WHICH WLY FLOW AHEAD OF THE FRONT
DETERRED MOISTURE TRANSPORT AND RESULTED IN JUST A FEW
SHOWERS...LATEST GUIDANCE SUGGEST A 12 HOUR WINDOW OF OPPORTUNITY TO
ADVECT MOISTURE OFF THE GULF INTO OUR REGION PRIOR TO FRONTAL
PASSAGE. THUS HAVE INCHED POPS UP A BIT FROM THE PREVIOUS FORECAST
FOR THE PERIOD LATE SATURDAY INTO SATURDAY NIGHT. IF MODEL TRENDS
CONTINUED...HIGH CHANCE OR LIKELY POPS MAY BECOME WARRANTED.
FRONTAL PASSAGE OCCURS SUNDAY INTO SUNDAY NIGHT WITH BETTER RAIN
CHANCES CONFINED TO THE EAST AND SOUTH SUNDAY AFTERNOON COMPARED
TO THE NW. HIGH PRESSURE BUILDS INTO THE REGION MONDAY WITH
ASSOCIATED DRIER AND MORE STABLE AIR MASS.
TEMPS THROUGH THE PERIOD WILL AVERAGE CLOSE TO NORMAL...MAYBE A
LITTLE ABOVE NORMAL SATURDAY ACROSS THE SE HALF AHEAD OF THE
FRONT...AND A COUPLE OF DEGREES BELOW NORMAL AREAWIDE MONDAY.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AS OF 1235 PM MONDAY...
THIS MORNING`S IFR/LIFR CLOUDS HAVE LIFTED TO VFR OR UNLIMITED WITH
HEATING. WINDS ARE LIGHT/VARIABLE MAINLY FROM THE WEST OR NORTH WITH
VFR CIGS AHEAD OF A COLD FRONT APPROACHING NC FROM THE NORTH. VFR
CONDITIONS WILL DOMINATE THIS EVENING... WITH CLOUDS FILLING BACK IN
BUT CIGS EXPECTED TO HOLD ABOVE 4 KFT AGL... HOWEVER WE DO EXPECT
ISOLATED TO SCATTERED SHOWERS AND A STORM OR TWO AHEAD OF THE FRONT
THIS AFTERNOON INTO EARLY EVENING... LIKELY TO AFFECT INT/GSO MAINLY
18Z-23Z... RDU/RWI MAINLY 20Z-01Z... AND FAY MAINLY 21Z-03Z...
ALTHOUGH GREATER ATMOSPHERIC INSTABILITY NEAR FAY MAY RESULT IN A
MORE PROLONGED RISK OF STORMS HERE. DUE TO A DRY LOW LEVEL
PROFILE... BRIEF CONVECTIVE WIND GUSTS OVER 30 MPH ARE POSSIBLE IN
AND NEAR SHOWERS OR STORMS... AND IT MUST BE STRESSED THAT THESE
STRONG GUSTS COULD OCCUR IN THE ABSENCE OF ANY LIGHTNING/THUNDER...
AS EVEN ORDINARY SHOWERS COULD PUT DOWN SOME SHORT-DURATION GUSTY
WINDS. DUE TO THE SHORT DURATION OF GUST THREAT NEAR
SHOWERS/STORMS... WILL NOT INCLUDE AS A DOMINANT CONDITION INT HE
TAFS. CIGS ARE LIKELY TO REMAIN PREDOMINANTLY VFR IN AND NEAR
SHOWERS/STORMS WITH BRIEF MVFR VSBYS POSSIBLE. BY MID TO LATE
EVENING... THE FRONT WILL BE MOVING SOUTHWARD THROUGH NC... AND A
SHIFT OF WINDS TO BE FROM THE NORTHEAST AND INCREASE IN SPEED
(SUSTAINED UP TO 8-12 KTS AND GUSTS OF 13-20 KTS) IS LIKELY NEAR AND
IN THE HOURS BEHIND THE FRONT AS COOLER AIR RUSHES IN FROM THE
NORTH. VFR CIGS ARE LIKELY TO HOLD THROUGH EARLY TUE AFTERNOON WITH
CLOUDS SCATTERING OUT ACROSS NRN NC. ALSO... AFTER 13Z... WINDS WILL
BECOME MORE UNIFORMLY FROM THE ENE THROUGH THE MIXED LAYER AT SPEEDS
OF 8-10 KTS.
LOOKING BEYOND 18Z TUESDAY... VFR WITH THE FOLLOWING EXCEPTIONS:
SHALLOW IFR FOG IS POSSIBLE WITHIN STABLE SURFACE RIDGE EARLY
WEDNESDAY MORNING. A WARM FRONT EXPECTED TO SHIFT TOWARD THE NE OVER
NC MAY BRING A QUICK MVFR SHOWER THURSDAY AFTERNOON. ANOTHER COLD
FRONT COULD BRING BETTER COVERAGE OF MVFR/IFR SHOWERS/STORMS ON
SATURDAY. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...TH
NEAR TERM...HARTFIELD
SHORT TERM...WSS
LONG TERM...WSS
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1235 PM EDT MON SEP 16 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH FROM THE NORTH LATE THIS AFTERNOON...
THEN PUSH SOUTH THROUGH THE AREA THIS EVENING INTO TONIGHT. CANADIAN
HIGH PRESSURE WILL BUILD INTO THE REGION ON TUESDAY AND PERSIST
THROUGH WEDNESDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 920 AM MONDAY...
UPDATE THROUGH REST OF TODAY: THE ISOLATED BAND OF SHALLOW BUT VERY
HEAVY RAIN SHOWERS WHICH PASSED THROUGH THE TRIANGLE EARLY THIS
MORNING IS MOVING QUICKLY EASTWARD THROUGH THE CENTRAL COASTAL
PLAIN. THESE SHOWERS APPEAR TO HAVE BEEN DRIVEN BY INTENSE LOW LEVEL
MOIST UPGLIDE (NOTED ON RAP OUTPUT AT 300K) ALONG A PROMINENT TONGUE
OF HIGH SURFACE THETA-E NOSING UP THROUGH THE ERN SANDHILLS TOWARD
RALEIGH/WILSON/GOLDSBORO... POSSIBLY AUGMENTED BY A FEW DOZEN J/KG
OF CAPE OBSERVED ON RAP PROXIMITY SOUNDINGS. THIS WAS AN INTERESTING
OCCURRENCE AS IT WAS DRIVEN BY SUBTLE AND SMALL YET STRONG FORCING
FEATURES... CONFINED TO THE LOWEST 2.5 KM WITH VERY DRY/STABLE AIR
ABOVE... THAT WERE POORLY HANDLED BY LAST NIGHT`S COMPUTER MODEL
GUIDANCE. A FEW LIGHTER AND MORE PATCHY SHOWERS TRAILING THE HEAVIER
RAINBAND ARE EXPECTED TO ALSO SHIFT EAST IN THE NEXT FEW HOURS
ACCORDING TO THE LATEST HRRR. WILL CARRY A MENTION OF ISOLATED
SHOWERS FOR THE REST OF THE MORNING EAST OF RDU... THEN EXPECT A
BRIEF LULL IN ANY PRECIP CHANCES THROUGH EARLY AFTERNOON AS DAYTIME
HEATING HELPS TO MIX OUT THE VERY MOIST LOW LEVELS OVER MUCH OF
CENTRAL NC... WHILE DRIER DEW POINTS AND LOWER 925-850 MB THETA-E
FILTER IN FROM THE WEST AHEAD OF THE COLD FRONT APPROACHING FROM THE
NORTH. WE SHOULD SEE ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS
PUSHING IN FROM THE NORTH VERY LATE THIS AFTERNOON INTO EARLY
EVENING JUST AHEAD OF THE FRONT... FORCED BY INCREASING MASS
CONVERGENCE IN THE LOWER LEVELS AND INCREASING UPPER DIVERGENCE IN
THE RIGHT ENTRANCE REGION OF THE STRENGTHENING JET FOCUSED IN THE
UPPER ST LAWRENCE VALLEY. MID LEVEL MOISTURE IS EXPECTED TO RISE
QUITE A BIT LATER THIS AFTERNOON WITH PW REBOUNDING ABOVE 1.4
INCHES... SO THESE LATE-DAY SHOWERS SHOULD BE DEEPER... ALTHOUGH WE
SHOULD STILL ONLY SEE 100 J/KG OR LESS OF MLCAPE... PERHAPS NEAR 200
J/KG IN THE EXTREME SE WHERE A MENTION OF THUNDER WILL BE RETAINED.
TEMPS ARE TRICKY AND WILL DEPEND ON THE BEHAVIOR OF THE STRATOCU
EAST OF THE TRIAD. THESE CLOUDS LOOK TO BE MOVING STEADILY EASTWARD
HOWEVER WITH SOME GOOD BREAKS IN THE CLOUDS... SO WITH AN
ABOVE-NORMAL 12Z GSO THICKNESS OF 1394 M... STILL EXPECT HIGHS OF
83-87 WITH MOSTLY CLOUDY SKIES BECOMING PARTLY CLOUDY. -GIH
TONIGHT:
WILL KEEP A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS ALONG AND
EAST OF HWY 1 THIS EVE WHERE THE RELATIVE BEST LOW-LEVEL MOISTURE
AND DESTABILIZATION IS EXPECTED...WITH ANY POTENTIAL FOR THUNDER
CONFINED TO THE SANDHILLS/SE COASTAL PLAIN. EXPECT CHANCES ENDING
FROM NW-SE OR NNW-SSE BY MIDNIGHT AS A DRIER /MORE STABLE/ AIRMASS
ADVECTS INTO THE REGION IN THE WAKE OF THE FRONT. LOWS TONIGHT WILL
BE DRIVEN BY COLD ADVECTION AND WILL DEPEND ON THE PRECISE TIMING OF
THE COLD FRONTAL PASSAGE...MEANING FCST LOW TEMPS COULD EASILY BUST
BY SEVERAL DEGREES. BASED ON THE LATEST FROPA TIMING (21-03Z N-S)...
EXPECT LOWS RANGING FROM THE UPPER 50S NEAR THE VA BORDER TO THE
LOWER/MID 60S NEAR THE SC BORDER. -VINCENT
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 300 AM MONDAY...
HIGH PRESSURE WILL BUILD INTO THE MID-ATLANTIC ON TUE...WITH A
PRONOUNCED SFC RIDGE AIS EXTENDING S/SW INTO CENTRAL NC. GIVEN A
DRY/STABLE AIRMASS IN PLACE IN THE WAKE OF THE COLD FRONT...EXPECT
CLEARING SKIES WITH HIGHS IN THE MID/UPPER 70S TO NEAR 80F...WARMEST
SOUTH AND COOLEST NORTH. LOWS TUE NIGHT RANGING FROM ~50F AT THE VA
BORDER TO THE MID/UPPER 50S SOUTH. -VINCENT
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 300 AM MONDAY...
CHILLY CONTINENTAL POLAR HIGH PRESSURE CENTERED OVER SOUTHERN
ONTARIO THIS MORNING WILL MODIFY AS IT BUILDS TO THE NORTHERN MIDDLE
ATLANTIC STATES BY MID WEEK. FORECAST GUIDANCE SUGGESTS THE RIDGE
AXIS WILL THEN CONTINUE TO EXTEND SOUTHWESTWARD ALONG AND EVENTUALLY
JUST OFFSHORE THE EAST COAST...SUPPORTED BY LONGWAVE RIDGING ALOFT
DOWNSTREAM OF A SERIES OF STRONG UPPER LOWS FORECAST TO MIGRATE
EASTWARD ALONG THE US/CANADIAN BORDER IN PROGRESSIVE LATE SUMMER
FLOW. THE FIRST OF THESE UPPER LOWS WILL PROPEL A COLD FRONT INTO
THE EASTERN US THIS WEEKEND...WITH FAVORED TIMING IN CENTRAL NC
DURING THE SECOND HALF OF THE WEEKEND - WITH AVERAGE TO
SLIGHTLY ABOVE FORECAST CONFIDENCE DUE TO TYPICAL TROUGH ALOFT
TIMING...AMPLITUDE...AND TILT DIFFERENCES DEPICTED BY THE MEDIUM
RANGE NWP GUIDANCE AT THAT TIME RANGE.
RETURN FLOW AROUND THE SURFACE RIDGE WILL PROMOTE A VEERING OF THE
LOW LEVEL FLOW FROM NE-ENE DURING THE MIDDLE OF THE WEEK - WITH SCT
TO BKN STRATOCUMULUS FROM MOISTURE TRAPPED BENEATH A SUBSIDENCE
INVERSION WED-WED NIGHT - TO A WARMING S-SW COMPONENT BY FRI-SAT.
THE ASSOCIATED WARMING WILL SEND TEMPERATURES BACK INTO THE LOWER TO
MIDDLE 80S AHEAD OF THE AFOREMENTIONED APPROACHING COLD FRONT...
WARMEST FRI-SAT. LOWS WILL MODIFY AS WELL...FROM COOLEST READINGS IN
THE 50S THU MORNING...TO MIDDLE 60S SAT NIGHT.
PRECIPITATION CHANCES WILL BE TIED TO THE PASSAGE OF THE FRONT
THROUGH WEAK WARM SECTOR INSTABILITY. HAVE ACCORDINGLY REMOVED
PRECIPITATION CHANCES FROM FRI AND INSTEAD CONFINED A LOW CHANCE OF
SHOWERS AND STORMS TO THE FAVORED FRONTAL PASSAGE TIMING LATE
SAT-SUN.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AS OF 1235 PM MONDAY...
THIS MORNING`S IFR/LIFR CLOUDS HAVE LIFTED TO VFR OR UNLIMITED WITH
HEATING. WINDS ARE LIGHT/VARIABLE MAINLY FROM THE WEST OR NORTH WITH
VFR CIGS AHEAD OF A COLD FRONT APPROACHING NC FROM THE NORTH. VFR
CONDITIONS WILL DOMINATE THIS EVENING... WITH CLOUDS FILLING BACK IN
BUT CIGS EXPECTED TO HOLD ABOVE 4 KFT AGL... HOWEVER WE DO EXPECT
ISOLATED TO SCATTERED SHOWERS AND A STORM OR TWO AHEAD OF THE FRONT
THIS AFTERNOON INTO EARLY EVENING... LIKELY TO AFFECT INT/GSO MAINLY
18Z-23Z... RDU/RWI MAINLY 20Z-01Z... AND FAY MAINLY 21Z-03Z...
ALTHOUGH GREATER ATMOSPHERIC INSTABILITY NEAR FAY MAY RESULT IN A
MORE PROLONGED RISK OF STORMS HERE. DUE TO A DRY LOW LEVEL
PROFILE... BRIEF CONVECTIVE WIND GUSTS OVER 30 MPH ARE POSSIBLE IN
AND NEAR SHOWERS OR STORMS... AND IT MUST BE STRESSED THAT THESE
STRONG GUSTS COULD OCCUR IN THE ABSENCE OF ANY LIGHTNING/THUNDER...
AS EVEN ORDINARY SHOWERS COULD PUT DOWN SOME SHORT-DURATION GUSTY
WINDS. DUE TO THE SHORT DURATION OF GUST THREAT NEAR
SHOWERS/STORMS... WILL NOT INCLUDE AS A DOMINANT CONDITION INT HE
TAFS. CIGS ARE LIKELY TO REMAIN PREDOMINANTLY VFR IN AND NEAR
SHOWERS/STORMS WITH BRIEF MVFR VSBYS POSSIBLE. BY MID TO LATE
EVENING... THE FRONT WILL BE MOVING SOUTHWARD THROUGH NC... AND A
SHIFT OF WINDS TO BE FROM THE NORTHEAST AND INCREASE IN SPEED
(SUSTAINED UP TO 8-12 KTS AND GUSTS OF 13-20 KTS) IS LIKELY NEAR AND
IN THE HOURS BEHIND THE FRONT AS COOLER AIR RUSHES IN FROM THE
NORTH. VFR CIGS ARE LIKELY TO HOLD THROUGH EARLY TUE AFTERNOON WITH
CLOUDS SCATTERING OUT ACROSS NRN NC. ALSO... AFTER 13Z... WINDS WILL
BECOME MORE UNIFORMLY FROM THE ENE THROUGH THE MIXED LAYER AT SPEEDS
OF 8-10 KTS.
LOOKING BEYOND 18Z TUESDAY... VFR WITH THE FOLLOWING EXCEPTIONS:
SHALLOW IFR FOG IS POSSIBLE WITHIN STABLE SURFACE RIDGE EARLY
WEDNESDAY MORNING. A WARM FRONT EXPECTED TO SHIFT TOWARD THE NE OVER
NC MAY BRING A QUICK MVFR SHOWER THURSDAY AFTERNOON. ANOTHER COLD
FRONT COULD BRING BETTER COVERAGE OF MVFR/IFR SHOWERS/STORMS ON
SATURDAY. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...TH
NEAR TERM...HARTFIELD/VINCENT
SHORT TERM...VINCENT
LONG TERM...MWS
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
920 AM EDT MON SEP 16 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH FROM THE NORTH LATE THIS AFTERNOON...
THEN PUSH SOUTH THROUGH THE AREA TONIGHT. CANADIAN HIGH PRESSURE
WILL BUILD INTO THE REGION ON TUESDAY AND PERSIST THROUGH WEDNESDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 920 AM MONDAY...
UPDATE THROUGH REST OF TODAY: THE ISOLATED BAND OF SHALLOW BUT VERY
HEAVY RAIN SHOWERS WHICH PASSED THROUGH THE TRIANGLE EARLY THIS
MORNING IS MOVING QUICKLY EASTWARD THROUGH THE CENTRAL COASTAL
PLAIN. THESE SHOWERS APPEAR TO HAVE BEEN DRIVEN BY INTENSE LOW LEVEL
MOIST UPGLIDE (NOTED ON RAP OUTPUT AT 300K) ALONG A PROMINENT TONGUE
OF HIGH SURFACE THETA-E NOSING UP THROUGH THE ERN SANDHILLS TOWARD
RALEIGH/WILSON/GOLDSBORO... POSSIBLY AUGMENTED BY A FEW DOZEN J/KG
OF CAPE OBSERVED ON RAP PROXIMITY SOUNDINGS. THIS WAS AN INTERESTING
OCCURRENCE AS IT WAS DRIVEN BY SUBTLE AND SMALL YET STRONG FORCING
FEATURES... CONFINED TO THE LOWEST 2.5 KM WITH VERY DRY/STABLE AIR
ABOVE... THAT WERE POORLY HANDLED BY LAST NIGHT`S COMPUTER MODEL
GUIDANCE. A FEW LIGHTER AND MORE PATCHY SHOWERS TRAILING THE HEAVIER
RAINBAND ARE EXPECTED TO ALSO SHIFT EAST IN THE NEXT FEW HOURS
ACCORDING TO THE LATEST HRRR. WILL CARRY A MENTION OF ISOLATED
SHOWERS FOR THE REST OF THE MORNING EAST OF RDU... THEN EXPECT A
BRIEF LULL IN ANY PRECIP CHANCES THROUGH EARLY AFTERNOON AS DAYTIME
HEATING HELPS TO MIX OUT THE VERY MOIST LOW LEVELS OVER MUCH OF
CENTRAL NC... WHILE DRIER DEW POINTS AND LOWER 925-850 MB THETA-E
FILTER IN FROM THE WEST AHEAD OF THE COLD FRONT APPROACHING FROM THE
NORTH. WE SHOULD SEE ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS
PUSHING IN FROM THE NORTH VERY LATE THIS AFTERNOON INTO EARLY
EVENING JUST AHEAD OF THE FRONT... FORCED BY INCREASING MASS
CONVERGENCE IN THE LOWER LEVELS AND INCREASING UPPER DIVERGENCE IN
THE RIGHT ENTRANCE REGION OF THE STRENGTHENING JET FOCUSED IN THE
UPPER ST LAWRENCE VALLEY. MID LEVEL MOISTURE IS EXPECTED TO RISE
QUITE A BIT LATER THIS AFTERNOON WITH PW REBOUNDING ABOVE 1.4
INCHES... SO THESE LATE-DAY SHOWERS SHOULD BE DEEPER... ALTHOUGH WE
SHOULD STILL ONLY SEE 100 J/KG OR LESS OF MLCAPE... PERHAPS NEAR 200
J/KG IN THE EXTREME SE WHERE A MENTION OF THUNDER WILL BE RETAINED.
TEMPS ARE TRICKY AND WILL DEPEND ON THE BEHAVIOR OF THE STRATOCU
EAST OF THE TRIAD. THESE CLOUDS LOOK TO BE MOVING STEADILY EASTWARD
HOWEVER WITH SOME GOOD BREAKS IN THE CLOUDS... SO WITH AN
ABOVE-NORMAL 12Z GSO THICKNESS OF 1394 M... STILL EXPECT HIGHS OF
83-87 WITH MOSTLY CLOUDY SKIES BECOMING PARTLY CLOUDY. -GIH
TONIGHT:
WILL KEEP A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS ALONG AND
EAST OF HWY 1 THIS EVE WHERE THE RELATIVE BEST LOW-LEVEL MOISTURE
AND DESTABILIZATION IS EXPECTED...WITH ANY POTENTIAL FOR THUNDER
CONFINED TO THE SANDHILLS/SE COASTAL PLAIN. EXPECT CHANCES ENDING
FROM NW-SE OR NNW-SSE BY MIDNIGHT AS A DRIER /MORE STABLE/ AIRMASS
ADVECTS INTO THE REGION IN THE WAKE OF THE FRONT. LOWS TONIGHT WILL
BE DRIVEN BY COLD ADVECTION AND WILL DEPEND ON THE PRECISE TIMING OF
THE COLD FRONTAL PASSAGE...MEANING FCST LOW TEMPS COULD EASILY BUST
BY SEVERAL DEGREES. BASED ON THE LATEST FROPA TIMING (21-03Z N-S)...
EXPECT LOWS RANGING FROM THE UPPER 50S NEAR THE VA BORDER TO THE
LOWER/MID 60S NEAR THE SC BORDER. -VINCENT
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 300 AM MONDAY...
HIGH PRESSURE WILL BUILD INTO THE MID-ATLANTIC ON TUE...WITH A
PRONOUNCED SFC RIDGE AIS EXTENDING S/SW INTO CENTRAL NC. GIVEN A
DRY/STABLE AIRMASS IN PLACE IN THE WAKE OF THE COLD FRONT...EXPECT
CLEARING SKIES WITH HIGHS IN THE MID/UPPER 70S TO NEAR 80F...WARMEST
SOUTH AND COOLEST NORTH. LOWS TUE NIGHT RANGING FROM ~50F AT THE VA
BORDER TO THE MID/UPPER 50S SOUTH. -VINCENT
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 300 AM MONDAY...
CHILLY CONTINENTAL POLAR HIGH PRESSURE CENTERED OVER SOUTHERN
ONTARIO THIS MORNING WILL MODIFY AS IT BUILDS TO THE NORTHERN MIDDLE
ATLANTIC STATES BY MID WEEK. FORECAST GUIDANCE SUGGESTS THE RIDGE
AXIS WILL THEN CONTINUE TO EXTEND SOUTHWESTWARD ALONG AND EVENTUALLY
JUST OFFSHORE THE EAST COAST...SUPPORTED BY LONGWAVE RIDGING ALOFT
DOWNSTREAM OF A SERIES OF STRONG UPPER LOWS FORECAST TO MIGRATE
EASTWARD ALONG THE US/CANADIAN BORDER IN PROGRESSIVE LATE SUMMER
FLOW. THE FIRST OF THESE UPPER LOWS WILL PROPEL A COLD FRONT INTO
THE EASTERN US THIS WEEKEND...WITH FAVORED TIMING IN CENTRAL NC
DURING THE SECOND HALF OF THE WEEKEND - WITH AVERAGE TO
SLIGHTLY ABOVE FORECAST CONFIDENCE DUE TO TYPICAL TROUGH ALOFT
TIMING...AMPLITUDE...AND TILT DIFFERENCES DEPICTED BY THE MEDIUM
RANGE NWP GUIDANCE AT THAT TIME RANGE.
RETURN FLOW AROUND THE SURFACE RIDGE WILL PROMOTE A VEERING OF THE
LOW LEVEL FLOW FROM NE-ENE DURING THE MIDDLE OF THE WEEK - WITH SCT
TO BKN STRATOCUMULUS FROM MOISTURE TRAPPED BENEATH A SUBSIDENCE
INVERSION WED-WED NIGHT - TO A WARMING S-SW COMPONENT BY FRI-SAT.
THE ASSOCIATED WARMING WILL SEND TEMPERATURES BACK INTO THE LOWER TO
MIDDLE 80S AHEAD OF THE AFOREMENTIONED APPROACHING COLD FRONT...
WARMEST FRI-SAT. LOWS WILL MODIFY AS WELL...FROM COOLEST READINGS IN
THE 50S THU MORNING...TO MIDDLE 60S SAT NIGHT.
PRECIPITATION CHANCES WILL BE TIED TO THE PASSAGE OF THE FRONT
THROUGH WEAK WARM SECTOR INSTABILITY. HAVE ACCORDINGLY REMOVED
PRECIPITATION CHANCES FROM FRI AND INSTEAD CONFINED A LOW CHANCE OF
SHOWERS AND STORMS TO THE FAVORED FRONTAL PASSAGE TIMING LATE
SAT-SUN.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AS OF 640 AM MONDAY...
06Z TAF PERIOD:
IFR CEILINGS AND ISOLD SHOWER ACTIVITY CAN BE EXPECTED ACROSS THE
PIEDMONT (PRIMARILY RDU TERMINAL) THROUGH 16Z...WITH SUB-VFR FOG
AND/OR CEILINGS AND ISOLD SHOWER ACTIVITY POSSIBLE AT THE EASTERN
TERMINALS IN THE SAME TIME FRAME. ANY SUB-VFR CEILINGS ARE EXPECTED
TO SCATTER OUT AND LIFT TO VFR BY LATE MORNING TO EARLY AFTERNOON
(15-18Z). A BACK DOOR COLD FRONT WILL SURGE SOUTHWARD THROUGH
CENTRAL NC THIS EVENING INTO TONIGHT AS STRONG CANADIAN HIGH
PRESSURE BUILDS INTO THE MID-ATLANTIC. EXPECT A FRONTAL PASSAGE
SIMILAR TO LAST FRI/SAT...I.E. VFR ASIDE FROM A SMALL CHANCE FOR
ISOLD CONVECTION AT THE FAY/RWI TERMINALS AND A SHORT PERIOD OF
BREEZY NORTHEAST WINDS IN THE WAKE OF THE FRONT MON NIGHT AND TUE
MORNING.
LOOKING AHEAD:
EXPECT DRY/VFR CONDITIONS ASSOCIATED WITH HIGH PRESSURE TO
PREVAIL THROUGH MID-WEEK. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...HARTFIELD/VINCENT
SHORT TERM...VINCENT
LONG TERM...MWS
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
140 AM EDT MON SEP 16 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH FROM THE NORTH LATE THIS AFTERNOON...
THEN PUSH SOUTH THROUGH THE AREA THIS EVENING INTO TONIGHT. CANADIAN
HIGH PRESSURE WILL BUILD INTO THE REGION ON TUESDAY AND PERSIST
THROUGH WEDNESDAY.
&&
.NEAR TERM /TONIGHT/...
AS OF 930 PM SUNDAY...
REST OF TONIGHT: STILL ANTICIPATE A QUIET NIGHT BUT WITH INCREASING
CLOUDS... AND TEMPS MARKEDLY WARMER THAN LAST NIGHT. MSLP AND
SURFACE THETA-E ANALYSES SHOW THAT THE SURFACE HIGH CENTER HAS SLID
OFFSHORE OVER THE LAST SEVERAL HOURS... AND THE SOUTHEASTERLY LOW
LEVEL RETURN FLOW IS ALREADY DRAWING HIGHER DEW POINTS INTO SOUTHERN
AND WESTERN NC. THIS TREND SHOULD PERSIST OVERNIGHT WITH BETTER LOW
LEVEL MOISTURE STEADILY SPREADING OVER CENTRAL NC FROM THE SSW. WARM
AIR ADVECTION AND INCREASING MOISTURE ARE ALSO EVIDENT AT 925-850 MB
WITH HIGHER TEMPS AND LOWER DEW POINT DEPRESSIONS TO OUR SOUTH.
EXPECT AN OVERSPREADING OF STRATOCUMULUS FROM SW TO NE OVER THE
PIEDMONT AND WRN SANDHILLS THROUGH THE NIGHT... A PATTERN PICKED UP
WELL BY THE LATEST HRRR OUTPUT. WE`LL ALSO SEE THE MID AND HIGH
CLOUDS OVER VA/WRN NC/NRN GA (ASSOCIATED WITH A MID LEVEL JET STREAK
TO OUR NW) SPREADING EASTWARD ACROSS NC THROUGH THE NIGHT. IN ALL...
ACROSS CENTRAL NC... EXPECT FAIR TO PARTLY CLOUDY SKIES EAST WITH
SKIES BECOMING MOSTLY CLOUDY WEST. THE HRRR AND WRF-ARW/WRF-NMM
INDICATE A FEW SPRINKLES OVERNIGHT... CERTAINLY NOT OUT OF THE
QUESTION GIVEN THE ANTICIPATED MOIST UPGLIDE AT 295-300K WITH THE
NORTHWARD-MOVING 925-850 MB WARM FRONTAL ZONE. WITH THE CLOUDS
SUPPRESSING COOLING... HAVE NUDGED UP LOWS A BIT... TO RANGE FROM 59
IN THE RURAL NORTHERN BORDER SECTIONS TO 66 NEAR THE SC BORDER. -GIH
&&
.SHORT TERM /MONDAY AND MONDAY NIGHT/...
AS OF 245 PM SUNDAY...
SHORTWAVE ENERGY DIVING SOUTHEAST OUT OF SOUTHCENTRAL CANADA WILL
LEAD TO FURTHER AMPLIFICATION OF THE UPPER LEVEL TROUGH OVER THE
MID-ATLANTIC AND NEW ENGLAND ON MONDAY. HEIGHT RISES
/SUBSIDENCE/ IN THE WAKE OF THE SHORTWAVE OVER THE OH VALLEY WILL
ALLOW CANADIAN HIGH PRESSURE TO BUILD RAPIDLY SOUTHEAST INTO THE
MID-ATLANTIC LATE MON/MON NIGHT...DRIVING A BACK DOOR COLD FRONT
SOUTHWARD THROUGH CENTRAL NC MONDAY EVENING.
LIMITED LOW-LEVEL MOISTURE RETURN(BL DEWPOINTS ONLY IN THE LOWER TO
MID 60S)AND CONTINUED WARM AIR ALOFT WILL SURRENDER MLCAPE VALUES OF
ONLY 300-700 J/KG ACROSS THE FAR SE ZONES MONDAY AFTERNOON. AT THE
SAME TIME...THE SOUTHWARD MOVING COLD FRONT WILL BEGIN TO OUTRUN
BOTH JET AND SHORTWAVE TROUGH SUPPORT SHIFTING OFF THE NORTHERN
MID-ATLANTIC COAST...RESULTING IN ONLY ISOLATED TO SLIGHT POPS
ACROSS THE AREA MONDAY AFTERNOON AND MONDAY EVENING AS THE FRONT
PUSHES SOUTH THROUGH THE AREA BY AROUND 06Z TUESDAY WITH DELAYED
CLEARING IN THE WAKE OF THE FRONT THROUGH DAYBREAK GIVEN RELATIVELY
MOIST NELY LOW-LEVEL FLOW.
1000-850 MB THICKNESSES WILL INCREASE ANOTHER 10 TO 15 METERS IN
ADVANCE OF THE FRONT MONDAY AFTERNOON...YIELDING ANOTHER 3-5 DEGREES
OF WARMTH. HIGHS IN THE LOWER 80S NORTH TO MID/UPPER 80S SOUTH.
LOWS MON NIGHT WILL BE DRIVEN BY COLD ADVECTION AND WILL DEPEND ON
CLOUD COVER. LOWS RANGING FROM THE UPPER 50S NEAR THE VA BORDER TO
THE LOWER/MID 60S SOUTH.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
AS OF 245 PM SUNDAY...
TUESDAY THROUGH THURSDAY...BEHIND THE DEPARTING FRONT...SURFACE HIGH
PRESSURE WILL GRADUALLY BUILD EAST AND RIDGE DOWN INTO THE REGION
TUESDAY AND WEDNESDAY BEFORE SHIFTING SOUTH AND BECOMING SITUATED
OVERHEAD BY THURSDAY. THIS WILL RESULT IN FAIR WEATHER FOR CENTRAL
NC. HIGH TEMPS WILL GRADUALLY MODERATE DURING THIS TIME FRAME...FROM
MOSTLY THE UPPER 70S ON TUESDAY TO THE LOW/MID 80S BY THURSDAY.
OVERNIGHT LOWS WILL ALSO UNDERGO A MODERATING TREND...WITH MID/UPPER
50S ON TUESDAY NIGHT AND LOW 60S BY THURSDAY NIGHT.
FRIDAY THROUGH SUNDAY...THE AFOREMENTIONED HIGH PRESSURE WILL BEGIN
TO SHIFT OFFSHORE ON FRIDAY AHEAD OF OUR NEXT SYSTEM. THE RESULTANT
RETURN FLOW/INCREASING MOISTURE MAY ALLOW A FEW SHOWERS/STORMS TO
OCCUR FRIDAY AFTERNOON...MAINLY ACROSS THE WEST...BUT MOST PLACES
SHOULD REMAIN DRY. TEMPS SHOULD CONTINUE THEIR MODERATION TREND...
WITH GENERALLY MID (MAYBE SOME UPPER) 80S EXPECTED. THEN A FRONT
WILL APPROACH THE AREA OVER THE WEEKEND...ALTHOUGH THERE HAS BEEN A
SLOWING TREND WITH THE CURRENT MODEL RUN. DUE TO THE TIMING
UNCERTAINTY...WILL NOT GO ANY HIGHER THAN LOW END CHANCE POPS FOR
NOW...MAINLY CENTERED AROUND THE LATE SATURDAY/SUNDAY TIME FRAME.
TEMPS MAY BE TEMPERED SOME DUE TO THE INCREASED CLOUD COVER...BUT
STILL IN LOW/MID 80S. OVERNIGHT LOWS WILL GENERALLY BE IN THE
LOW/MID 60S.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS OF 140 AM MONDAY...
06Z TAF PERIOD:
MVFR CEILINGS ARE EXPECTED TO DEVELOP OVER THE WESTERN PIEDMONT
(ALONG/WEST OF HWY 1) BETWEEN 08-12Z THIS MORNING...WITH THE
INT/GSO/RDU TERMINALS MOST LIKELY TO BE AFFECTED. FURTHER EAST...
CANNOT RULE OUT MVFR FOG AND/OR CEILINGS IN THE SAME TIME FRAME. ANY
SUB-VFR CEILINGS ARE EXPECTED TO SCATTER OUT AND LIFT TO VFR BY LATE
MORNING (15Z). A BACK DOOR COLD FRONT WILL SURGE SOUTHWARD THROUGH
CENTRAL NC THIS EVENING INTO TONIGHT AS STRONG CANADIAN HIGH
PRESSURE BUILDS INTO THE MID-ATLANTIC. EXPECT A FRONTAL PASSAGE
SIMILAR TO LAST FRI/SAT...I.E. VFR ASIDE FROM A SMALL CHANCE FOR
ISOLD CONVECTION AT THE FAY/RWI TERMINALS AND A SHORT PERIOD OF
BREEZY NORTHEAST WINDS IN THE WAKE OF THE FRONT MON NIGHT AND TUE
MORNING.
LOOKING AHEAD:
EXPECT DRY/VFR CONDITIONS ASSOCIATED WITH HIGH PRESSURE TO
PREVAIL THROUGH MID-WEEK. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...HARTFIELD
SHORT TERM...CBL
LONG TERM...KRR
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
144 AM EDT MON SEP 16 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE THROUGH THE REGION OVERNIGHT. AN AREA OF
HIGH PRESSURE WILL BEGIN TO WORK INTO THE AREA ON MONDAY AND WILL
REMAIN NEAR THE AREA THROUGH TUESDAY NIGHT. A WEAK DISTURBANCE
WILL MOVE INTO THE REGION ON WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
SHOWER ACTIVITY CONTINUES TO PROGRESS SOUTH AND EAST ACROSS THE FA
ALONG A COLD FRONT THAT CURRENTLY STRETCHES FROM AROUND IND TO CLE.
MAIN CONCERN WILL BE IF THE RAIN HOLDS TOGETHER OVERNIGHT TO MAKE
IT TO THE SOUTHERN HALF OF THE FA. THE 00Z KILN SOUNDING CONFIRMS
A DRY LAYER IN THE LOW LEVELS...AND THERE IS UNCERTAINTY WHETHER
THIS WILL ALLOW FOR MUCH /IF ANY/ MEASURABLE PRECIPITATION ACROSS
THE SOUTH. THE LATEST RAP RUNS HAVE TRENDED DRY ACROSS THE
TRI-STATE...AND ALTHOUGH THE SHOWER ACTIVITY HAS BEEN LEANING THAT
WAY...DID NOT HAVE ENOUGH CONFIDENCE TO GO LESS THAN CHANCE POPS
THERE. REGARDLESS...PRECIPITATION WILL REMAIN LIGHT OVERNIGHT WITH
AROUND A TENTH OF AN INCH OR LESS EXPECTED. ONLY MADE MINOR
ADJUSTMENTS TO THE PREVIOUS LOW TEMP FORECAST FOR TONIGHT.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
THE COLD FRONT WILL BE JUST SOUTH OF THE FA AT THE BEGINNING OF
THE SHORT TERM TIME PERIOD WITH ONLY THE CHANCE FOR A FEW LIGHT
SHOWERS ACROSS FAR SOUTHERN PORTIONS OF THE FA. A FEW ADDITIONAL
LIGHT SHOWERS WILL BE POSSIBLE DURING THE MORNING HOURS TO AROUND
MID DAY ACROSS CENTRAL OHIO WITH H8 WINDS OFF OF THE LAKE.
PRECIPITATION WILL TAPER OFF ACROSS THE FA BY THE AFTERNOON HOURS.
DRY CONDITIONS WILL BE PRESENT FOR THE REMAINDER OF THE SHORT TERM
TIME PERIOD AS HIGH PRESSURE BUILDS INTO THE REGION.
ALTHOUGH CLOUD COVER MAY DECREASE SLIGHTLY DURING THE DAYTIME
MORNING HOURS ON MONDAY ADDITIONAL CLOUD COVER WILL DEVELOP FOR
THE AFTERNOON HOURS WITH CAA. CLOUD COVER WILL DECREASE DURING THE
EVENING HOURS ON MONDAY AND BE MOSTLY CLEAR FOR A LARGE PORTION OF
THE OVERNIGHT HOURS MONDAY NIGHT.
COOL NORTHERLY FLOW AND CLOUD COVER WILL LIMIT TEMPERATURES FROM
RISING TOO MUCH ON MONDAY. HIGH TEMPERATURES WILL GENERALLY BE IN
THE MIDDLE 60S TO LOW 70S. AS CLOUD COVER AND WINDS BEGIN TO
DECREASE MONDAY NIGHT TEMPERATURES WILL FALL INTO THE MIDDLE 40S
TO LOWER 50S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
HIGH PRESSURE WILL BE CENTERED OVER NEW ENGLAND AT THE BEGINNING OF
THE FORECAST PERIOD PROVIDING DRY AND BELOW NORMAL CONDITIONS FOR
TUESDAY. BY WEDNESDAY...THE REGION WILL BE ON THE BACK SIDE OF THE
HIGH AND A RETURN FLOW WILL BRING WARMING TEMPERATURES AND AN
INCREASE IN HUMIDITY. PRECIPITATION CHANCES WILL RETURN BY WEDNESDAY
WITH 20 POPS...AND WILL INCREASE ON THURSDAY AND FRIDAY AS A CDFNT
PUSHES OUT OF THE PLAINS AND INTO THE OHIO VALLEY. AFT THE 00Z ECMWF
WAS A LITTLE QUICKER WITH THE FROPA FRIDAY...THE 12Z MODELS HAVE
COME INTO PRETTY GOOD AGREEMENT ON THE FRONTAL TIMING...PUSHING IT
THROUGH FRIDAY NIGHT. KEPT POPS FOR BOTH THURSDAY AND FRIDAY IN THE
CHANCE CATEGORY FOR NOW...BUT IF THE AGREEMENT CONTINUES INTO
TOMORROW...HIGHER POPS MIGHT BE WARRANTED. AS MENTIONED BEFORE THE
MODELS PUSH THE FRONT THROUGH THE REGION FRIDAY NIGHT. THE SOUTH AND
SOUTHEAST COULD SEE SOME LINGERING PCPN EARLY SATURDAY.
ANOTHER HIGH PRESSURE SYSTEM BUILDS DOWN FROM CANADA INTO THE GREAT
LAKES FOR SATURDAY NIGHT INTO SUNDAY.
TEMPERATURES WILL INCREASE FOR WEDNESDAY WITH HIGHS IN THE UPPER 70S
TO LOWER 80S. THURSDAY LOOKS LIKE THE WARMEST DAY OF THE WEEK WITH
HIGHS IN THE LOWER TO MID 80S...BEFORE CLOUDS AND PCPN DROP
TEMPERATURES BACK TO THE LOWER 80S ON FRIDAY. COOLER AIR WILL BUILD
IN NEXT WEEKEND. LOWS TUE NGT WILL BE IN THE 50S...BUT WILL WARM IN
THE 60S WED AND THU NIGHTS.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
SHOWERS WILL CONTINUE ALONG AND BEHIND A COLD FRONT MAKING ITS WAY
ACROSS OUR AREA TONIGHT. SOME MVFR VSBYS ASSOCIATED WITH LIGHT
PRECIPITATION COULD OCCUR THROUGH 08Z MAINLY AT KCMH/KLCK. LATER
TONIGHT IT APPEARS THAT MVFR VSBYS ASSOCIATED WITH MIST WILL
SPREAD ACROSS THE NORTHERN TERMINALS. ANY MVFR VSBYS SHOULD
IMPROVE SHORTLY AFTER SUNRISE. MVFR CIGS MAY DEVELOP CLOSER TO
SUNRISE AND LAST THROUGH THE LATE MORNING. AT THIS TIME IT APPEARS
THE HIGHEST CHANCE FOR THESE MVFR CIGS WILL BE ACROSS KCMH/KLCK.
AM MORE OPTIMISTIC FOR THE REST OF THE TERMINALS AND AM
FORECASTING CIGS TO REMAIN VFR THROUGHOUT THE TAF PERIOD. SOME
BREAKS ARE EXPECTED TO DEVELOP IN OUR CLOUD COVER BY THE
AFTERNOON. SKIES SHOULD BECOME MOSTLY CLEAR LATER IN THE EVENING.
OUTLOOK...THUNDERSTORMS ARE POSSIBLE THURSDAY INTO FRIDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...NOVAK
NEAR TERM...KURZ
SHORT TERM...NOVAK/SITES
LONG TERM...SITES
AVIATION...LATTO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
548 PM EDT MON SEP 16 2013
.SYNOPSIS...
HIGH PRESSURE WILL DOMINATE THE WEATHER PATTERN THROUGH THE MIDDLE
OF THE WEEK. AFTER A CHILLY START ON TUESDAY...A MILDER SOUTHWEST
FLOW WILL DEVELOP THROUGH THE SECOND HALF OF THE WEEK...WITH
TEMPERATURES CLIMBING SLIGHTLY ABOVE NORMAL. A COLD FRONT WILL
BRING SHOWERY CONDITIONS AS IT CROSSES THE REGION OVER THE
WEEKEND...FOLLOWED BY ANOTHER COOL CANADIAN AIR MASS FOR EARLY
NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
COLD FRONT WELL SOUTH OF THE STATE THIS AFTERNOON...BUT COLD AIR
STRATO CU REMAINS ACRS CENTRAL PA...WITH INCREASING BINOVC
DEVELOPING OVER ALL OF CENTRAL PA NOW. STILL A CHANCE FOR AN
INSTABILITY SHOWER MAINLY ALONG THE NORTHERN BORDER...BUT CHANCES
WILL DIMINISH QUICKLY AS WE APPROACH SUNSET. HIGHS WILL FINISH ON
THE COOL SIDE RANGING FROM AROUND 60 OVER THE NW TO AROUND 70F IN
THE LOWER SUSQ VALLEY.
SKIES WILL MORE RAPIDLY CLEAR THIS EVENING AS SPRAWLING HIGH PRES
BUILDS SEWD ACRS THE LWR LKS. THIS WILL BRING A CHILLY NIGHT TO
THE REGION...WITH TEMPS SLIPPING BACK INTO THE 30S AND 40S. A
FROST ADVISORY HAS BEEN POSTED FOR THE NORTHERN TIER.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY NIGHT/...
HIGH PRESSURE WILL MAINTAIN ITS GRIP ON THE REGION THRU WEDNESDAY
BEFORE SLOWLY RETREATING OFF THE SRN NEW ENGLAND COAST THURSDAY
NIGHT. A MILDER RETURN S-SW FLOW WILL BRING ABOUT A SLOW
MODERATION IN DAILY MAX/MIN TEMPS WITH A GRADUAL INCREASE IN
HUMIDITY. TOMORROW NIGHT WILL AGAIN BE CHILLY ACROSS THE NRN TIER
WITH PATCHY FROST POSSIBLE...WITH IS HIGHLIGHTED IN THE HWO.
SCT CONVECTION IS POSSIBLE OVER THE WRN AND CNTRL ZONES THU
AFTN INTO THU NGT...AS WARM FRONT BEGINS TO LIFT NEWD FROM THE
UPPER OH VLY INTO WRN PA.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
TEMPERATURES SHOULD PEAK ON FRIDAY AS THE AREA BREAKS INTO THE WARM
SECTOR AHEAD OF A WELL-DEFINED COLD FRONT PUSHING EWD THRU THE GRT
LKS/OH VLY. THERE ARE SOME MINOR TIMING DIFFS CONCERNING THE COLD
FROPA ON SATURDAY...WITH THE GFS/GEFS A LITTLE MORE PROGRESSIVE
THAN THE ECMWF. DECENT SURGE OF MSTR WITH ABV NORMAL PWATS AHEAD
OF THE FRONT SHOULD PROMOTE SCT CONVECTIVE RAINS ON DAY 5 AND 6.
SOME SHOWER ACTIVITY MAY LINGER INTO SUNDAY WITH THE UPPER TROUGH
PASSAGE...BEFORE HIGH PRESSURE BRINGS A COOLING TREND WITH DRY WX
FROM LATE IN THE WEEKEND INTO EARLY NEXT WEEK.
&&
.AVIATION /22Z MONDAY THROUGH SATURDAY/...
EARLY EVENING VISIBLE LOOP SHOWS SCT CU ACROSS MOST OF CENTRAL PA
WITH WIDESPREAD VFR CONDS. LOW LVL MOISTURE TRAPPED BENEATH
INVERSION IS RESULTING IN LOW CIGS JUST NORTH OF THE PA BORDER AND
CONCERN IS THAT SOME OF THESE LOW CIGS WILL CREEP INTO BFD EARLY THIS
EVENING BEFORE MUCH DRIER AIR ARRIVES LATE THIS EVENING. THE
LEADING EDGE OF THIS DRIER AIR MASS IS EVIDENT BY RAPID CLEARING
TAKING PLACE ALONG THE SOUTH SHORE OF LK ONTARIO AT 21Z. WOULD NOT
RULE OUT A PERIOD OF IFR CIGS AT BFD BTWN 23Z-03Z. RAP SOUNDINGS
SHOWS THE MUCH DRIER AIR ARRIVING ARND 03Z...AFTER WHICH MAINLY
CLEAR SKIES EXPECTED ACROSS ALL OF CENTRAL PA.
DIMINISHING WINDS...COOL TEMPS AND RELATIVELY WARM RIVER/STREAM
WATER...COULD RESULT IN PATCHY FOG IN THE DEEP VALLEYS OF THE
ALLEGHENIES EARLY TUE AM. CLIMATOLOGY WOULD INDICATE BFD AND IPT
COULD SEE A BRIEF VIS/CIG REDUCTION ARND DAWN.
LARGE HIGH PRESSURE SYSTEM AND ASSOCIATED DRY AIR MASS WILL BE OVR
THE REGION LATER TUESDAY...ENSURING A NEAR CERTAINTY OF MSUNNY
SKIES AND LIGHT WINDS.
OUTLOOK...
WED-THU...NO SIG WX. WIDESPREAD VFR.
FRI...ISOLD PM TSRA IMPACTS POSSIBLE W MTNS.
SAT...RAIN LIKELY WITH COLD FRONTAL PASSAGE. MVFR POSS MAINLY NW.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY FROM 2 AM TO 8 AM EDT TUESDAY FOR PAZ004>006-
037-041-042.
&&
$$
SYNOPSIS...RXR
NEAR TERM...RXR
SHORT TERM...STEINBUGL
LONG TERM...STEINBUGL
AVIATION...FITZGERALD/RXR
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
929 PM CDT TUE SEP 17 2013
.UPDATE...
MAIN FCST ISSUE STILL FACING THE OVERNIGHT PERIOD REVOLVES AROUND
THICK STRATUS DECK THAT HAS ENVELOPED MUCH OF EASTERN SOUTH
DAKOTA...ALONG WITH PCPN CHANCES LATER ON TONIGHT FOR THE FAR
WESTERN AREAS OF THE CWA.
WITH VSBYS BEGINNING TO FALL A BIT ACROSS THE ERN CWA...OPTED TO
ADD A MENTION OF DRIZZLE AND FOG TO THE EASTERN COUNTIES THROUGH
THE REMAINDER OF THE NIGHT. CONVECTION THAT FORMED EARLIER THIS
EVENING ACROSS THE WESTERN PART OF THE STATE IS HAVING A DIFFICULT
TIME MOVING INTO CENTRAL SOUTH DAKOTA. LATEST HRRR MODEL SUGGESTS
THAT ITS STILL POSSIBLE TO HAVE SOMETHING MOVE IN ON STRONG 700HPA
THETA-E FORCING OVERNIGHT. EXCEPT FOR A VICINITY MENTION IN THE
TAFS...AM GOING TO KEEP ANY MENTION OUT ATTM AND CONTINUE TO
MONITOR.
WITH ADDED MENTION OF DRIZZLE AND FOG...UPDATED ZONE FORECAST
PRODUCT WAS ISSUED EARLIER THIS EVENING.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT
THE MAIN CONCERN IN THE FORECAST IS CHANCES FOR CONVECTION. BUT
FIRST THINGS FIRST. LOOKS LIKE MOIST SOUTHERLY FLOW WILL KEEP
STRATUS DECK IN ACROSS THE EASTERN CWA...AND IT MAY ACTUALLY
SPREAD A LITTLE WEST OVERNIGHT. THIS WILL KEEP LOWS WARMER THAN
LAST NIGHT. ALSO NOT EXPECTING ANY PCPN OUTSIDE A FEW SPRINKLES.
THE NEXT PLAYER ACROSS THE NORTHERN PLAINS IS NOW MOVING THROUGH
THE PACIFIC NORTHWEST WITH QUITE AN ERUPTION OF STORMS OVER THE
ROCKIES. THIS ENERGY IS EXPECTED TO MOSTLY LIFT NORTH OF THE CWA
WEDNESDAY NIGHT AND THURSDAY. MEANWHILE AT THE SURFACE A COLD
FRONT WILL BE EDGING TOWARD THE WESTERN CWA BY LATE AFTERNOON.
THIS FRONT COULD KICK OFF SOME THUNDERSTORMS NEAR OR JUST BEHIND
THE ADVANCING FRONT. DURING MAX HEATING MLCIN GETS PRETTY LOW
AROUND THE MO VALLEY TOWARD EVENING. HOWEVER FURTHER EAST MLCIN
REMAINS FAIRLY HIGH UNDER EML ADVECTING ACROSS THE REGION. WILL
STILL HAVE TO COUNT ON FRONTAL FORCING TO GET STORMS GOING DURING
THE EVENING HOURS WITH A LACK OF ENERGY ALOFT. MOST OF THAT ENERGY
COMES ACROSS THE REGION VERY LATE WEDNESDAY NIGHT AND THURSDAY
POST SFC FRONT. TEMPERATURES ON WEDNESDAY SHOULD BE HOT MOST
AREAS...BUT ESPECIALLY THE MO RIVER VALLEY WHERE LL WINDS TREND SW
BY LATE AFTERNOON. THIS COULD ALLOW KPIR TO REACH 95 OR MAYBE EVEN
100 DEGREES. FOR THURSDAY AND THURSDAY NIGHT COOLER AND DRIER AIR
ADVECTS INTO THE REGION VIA SFC HIGH PRESSURE.
.LONG TERM...FRIDAY THROUGH TUESDAY
FAIRLY GOOD AGREEMENT EXISTS BETWEEN THE GFS AND ECMWF
DETERMINISTIC GUIDANCE IN DEPICTING AN UPPER RIDGE SETTLING OVER
THE REGION FOR THE END OF THE WORK WEEK/WEEKEND. SURFACE HIGH
PRESSURE THAT WILL DOMINATE THE FORECAST WILL BE SOURCED FROM THE
NORTHERN ROCKIES WITH MODIFIED PACIFIC CHARACTERISTICS...THUS
TEMPERATURES SHOULD RUN AROUND NORMAL WITH LOW DEWPOINTS. IDEAL
RADIATION CONDITIONS SET SATURDAY AM WILL BE THE COLDEST
MORNING...WITH RETURN FLOW BRINGING MILDER AIR BACK INTO THE
REGION FOR THE WEEKEND. AN UPPER TROF MOVES ACROSS THE AREA FOR
SUNDAY NIGHT...THOUGH MODELS ARE DIVIDED ON THE AMOUNT OF FORCING
AND MOISTURE RETURN...SO HAVE LOWERED POPS SLIGHTLY.
&&
.AVIATION...
00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
MVFR/SCT IFR CIGS WILL REMAIN OVER THE KABR/KATY TERMINALS THROUGH
12Z WEDNESDAY BEFORE BEGINNING TO BECOMING SCT AHEAD OF AN
APPROACHING COLD FRONT. LOOK FOR VCTS CONDS FOR THE KMBG/KPIR
TERMINALS FROM 04Z THROUGH 07Z AS CONVECTION CURRENTLY OCCURRING
IN SWRN SOUTH DAKOTA MOVES NORTHEAST. THE CONVECTION IS NOT
EXPECTED TO GET INTO THE KABR OR KATY AERODROMES.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...HINTZ
SHORT TERM...TDK
LONG TERM...CONNELLY
AVIATION...HINTZ
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
928 PM CDT TUE SEP 17 2013
.UPDATE...
ISSUED AT 924 PM CDT TUE SEP 17 2013
INCREASED THE COVERAGE OF DRIZZLE AND FOG AS STRONG THETA E
ADVECTION AROUND 925MB AND 850MB NOT PROVIDING THE AREA WITH MUCH
IN THE WAY OF SHOWER DEVELOPMENT. LATEST RAP AND NAM SOUNDINGS
SUGGEST A BIT MORE OF A CAP WHEN LIFTING A PARCEL FROM ABOUT 850MB
SO THE THREAT FOR THUNDERSTORMS IS FAIRLY LOW AS WELL...ALTHOUGH
THE GOING 20 TO 30 POPS ALREADY PRETTY LOW. DID PICK UP SOME
MEASURABLE DRIZZLE AT THE AIRPORT. THE BACK EDGE OF THE STRATUS
DOES APPEAR TO FINALLY BE SLOWING AS A DECK AROUND 1500 FEET
LOOKS TO BE DEVELOPING AND STREAMING NORTHWEST. THE VISIBILITIES
HAVE BEEN GRADUALLY IMPROVING SO AT THIS TIME NOT CONCERNED ABOUT
A DENSE FOG ADVISORY. AS ALWAYS ONE AREA TO WATCH WILL BE THE
WESTERN EDGE BETWEEN THE STRATUS AND CLEAR SKIES. THE STRONGEST
LLJ/THETA E ADVECTION WILL END AROUND 6Z SO THE POTENTIAL FOR THE
DRIZZLE TO DECREASE AFTER 6Z AND NOT BE NEARLY AS WIDESPREAD EARLY
WEDNESDAY MORNING.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 354 PM CDT TUE SEP 17 2013
THE MAIN FORECAST CHALLENGE TONIGHT IS NOT SO MUCH PRECIPITATION
CHANCES BUT MORE SO WITH CLOUD COVER. CURRENT SATELLITE DEPICTS THE
EDGE OF THE CLEARING JUST WEST OF CHAMBERLAIN AND GREGORY COUNTY.
THE NAM SOUNDINGS AND HUMIDITY TIME SECTIONS ARE TOO BULLISH AT THIS
TIME WITH THE CLEARING SO WERE NOT FOLLOWED FOR THE TONIGHT AND
EARLY WEDNESDAY TIME FRAME. WHAT LOOKED CLOSER WAS THE RAP13 AND
GFS40 SOUNDINGS AND SUBSEQUENT LOW LEVEL HUMIDITY FIELDS. THEY SHOW
A CLEARING TREND MOVING NORTHEASTWARD THROUGH OUR SOUTHWEST ZONES
TONIGHT...WITH CLOUD COVER PINWHEELING BACK TOWARD THE WEST IN OUR
EAST CENTRAL SD ZONES SUCH AS HURON. THIS IS HOW THE CLOUD FORECAST
WAS PLAYED...WITH CLEARING SKIES EDGING TOWARD YANKTON AS THE NIGHT
PROGRESSES...BUT LEAVING HURON CONSIDERABLY CLOUDY. THE MOISTURE
TONIGHT AND EARLY WEDNESDAY DOES BECOME MORE AND MORE SHALLOW. SO BY
WEDNESDAY...IT IS CONCEIVABLE THAT THE CLOUD COVER COULD EXIT OR MIX
OUT IN A BIG HURRY...WITH THE POSSIBLE EXCEPTION OF SOME LINGERING
STRATUS OR STRATOCU IN OUR FAR EASTERN ZONES UNTIL MIDDAY WEDNESDAY.
WITH OR WITHOUT CLOUDS...LOWS WILL BE IMPACTED MORE BY WARM MOIST
ADVECTION TONIGHT AND SOUTHERLY WINDS. THEREFORE MANY LOCATIONS WILL
NOT DROP OFF HARDLY AT ALL FROM THEIR CURRENT TEMPERATURES. AND MANY
LOCATIONS IN OUR EASTERN ZONES MAY EVEN WARM UP A TAD INTO MID
EVENING. TEMPERATURES ON WEDNESDAY STILL LOOK TO BE WELL ABOVE
NORMAL AHEAD OF THE ADVANCING COLD FRONT. CONCERNING RAIN
POTENTIAL...LOOKS TO BE SLIM OR NONE ON WEDNESDAY. BUT LINGERED A
FEW LIGHT SHOWERS ACROSS OUR EASTERN ZONES TONIGHT WHERE THE DEEPEST
LAYER MOISTURE RESIDES. THERE COULD BE SOME PATCHY FOG THROUGHOUT
PARTS OF OUR EASTERN ZONES LATE TONIGHT ALSO.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 354 PM CDT TUE SEP 17 2013
JET ENERGY HANGING BACK QUITE A BIT GOING INTO THE EVENING BACK
THROUGH THE ROCKIES...BUT APPEARS TO MAKE PROGRESS EASTWARD
THROUGH THE NIGHT AS TROUGH NUDGES UP AGAINST PLAINS RIDGE. PROSPECT
FOR CONVECTION FAIRLY MINIMAL WITH STRONGLY CAPPED ATMOSPHERE
AHEAD OF THE BOUNDARY...WHICH REALLY DOES NOT MAKE ITS APPROACH TO
THE CWA UNTIL TOWARD 06Z. MOST...IF NOT ALL...DEEP LAYER FORCING
FOR LIFT IS POST FRONTAL...WITH WITH ELEVATED CAPE ON THE ORDER OF
500-750 J/KG...SO SHOULD BE ABLE TO SCRAPE UP AN INCREASING POTENTIAL
FOR CONVECTION BY LATE NIGHT AND EARLY MORNING FOR POSTFRONTAL AREAS.
FOR ALL THE FAULTS...THE CANADIAN GLOBAL MAY ACTUALLY HAVE THE
CORRECTLY SLANTED VIEW OF THE PRECIP DISTRIBUTION...DEVELOPING
PRECIP A BIT SLOWER...AND A BIT MORE WESTWARD REMOVED FROM LOW
LEVEL FRONTAL POSITION BY VERY LATE WED NIGHT AND THURSDAY.
FOCUS FOR CONVECTION WILL GRADUALLY SHIFT SOUTHEAST WITH THE
PROGRESSION OF DIV Q/FRONTOGENETIC FORCING...WITH MAX FORCING
COMING TOGETHER PERHAPS EARLY MORNING IN THE NORTH/NORTHEAST...
AND AGAIN WITH MAIN JET ENTRANCE DRAGGING ACROSS IN THE AFTERNOON
FOR THE SOUTHEAST. AVERAGE OF A QUARTER TO THIRD INCH IS NOT HARD
TO SUPPORT...EVEN WITH THE DRIER LAYER BELOW CLOUD BASE. TEMPS
WILL BE SOMEWHAT DIFFICULT TO RECOVER MUCH WITH ABUNDANCE OF
CLOUDS... AND UNDERCUTTING COLD AIR ADVECTION DURING THE DAY.
WARMEST MAY SANDWICH THE AREA...BOTH NORTHWEST WHERE WILL GET SOME
SUNSHINE LATER IN THE DAY AND BETTER MIXING...AND THE FAR
SOUTHEAST WHERE SURFACE BOUNDARY WILL LINGER THROUGH THE EARLY
MORNING WITH A FAIRLY MILD START.
FRIDAY INTO SATURDAY WILL FEATURE A COOLER AIRMASS WORKING
SOUTHWARD INTO THE PLAINS...AND WILL BE BREEZY AS WELL WITH MIXING
SUGGESTING DEWPOINTS WELL DOWN INTO THE 30S. THIS WILL OPEN THE
DOOR ON WHAT LOOKS LIKE A CLASSIC RADIATIVE COOLING NIGHT ON
FRIDAY NIGHT...AND SHOULD AT LEAST GET CLOSE TO HAVING SOME UPPER
30S IN COLDER LOCATIONS ALONG/EAST OF INTERSTATE 29. SUPPORT IN
SOME OF THE ENSEMBLE MOS GUIDANCE
RIDGE REBUILDING ACROSS THE PLAINS THIS WEEKEND...AND AS COOL HIGH
SHIFTS EAST WILL GET MODERATING SOUTHERLY WIND FLOW DEVELOPING.
PROBABLY WILL NOT GET FULL IMPACT OF WARMING WINDS YET ON SATURDAY
FOR EASTERN AREAS WITH FAIRLY WEAK FLOW...BUT WEST WILL RESPOND
NICELY RETURNING BACK ABOVE NORMAL. INCREASING WINDS SATURDAY
NIGHT INTO SUNDAY...AS TROUGH IN THE ROCKIES MOVES EAST WITH
PRESSURE FALLS IN LEE ACROSS WESTERN PLAINS. MIXING WILL START TO
BE SOMEWHAT MORE CHALLENGED WITH STABILIZING PROFILES AND SOUTH TO
SOUTHEAST COMPONENT. ANOTHER FAIRLY SHORT WAVELENGTH TROUGH
EXPECTED TO PUSH ACROSS THE NORTHERN PLAINS IN THE SUNDAY NIGHT TO
MONDAY WINDOW...SOME UNCERTAINTY IN TIMING. HOWEVER...SHORT
WAVELENGTH DOES PRODUCE DECENT DYNAMIC FORCING FOR LIFT...AND
WHILE MOISTURE WILL BE SOMEWHAT CHALLENGED TO RETURN...HAVE KEPT
UP WITH GENERALLY MID TO HIGHER CHANCE POPS AS FRONTAL BOUNDARY
PUSHES ACROSS THE AREA. QUICKLY DRYING BEHIND...AND TEMPS
REMAINING MILD FOR TUESDAY WITH MEAN RIDGE BECOMING REESTABLISHED.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 740 PM CDT TUE SEP 17 2013
WIDE RANGE OF FLIGHT CATEGORIES OUT THERE THIS EVENING...RANGING FROM
LIFR IN PORTIONS OF SOUTHWEST MINNESOTA AND NORTHWEST IOWA TO VFR IN
SOUTH CENTRAL SOUTH DAKOTA. TOUGH CALL ON THE EVOLUTION OF STRATUS
AND FOG OVERNIGHT. THINK CLEARING WILL CONTINUE TO PUSH
EAST...PROBABLY BRINGING VFR CONDITIONS INTO KHON FOR A PERIOD...BUT
NOT MUCH FURTHER EAST. IFR AND LIFR STRATUS SHOULD HANG TOUGH IN THE
EAST FOR MUCH OF THE NIGHT INTO WEDNESDAY MORNING...WITH CIGS
PROBABLY LOWERING A BIT FROM WHERE THEY ARE NOW. POCKETS OF DRIZZLE
ALSO SEEM LIKELY THROUGH THE NIGHT...ENDING FROM SOUTHWEST TO
NORTHEAST AS THE MOISTURE LAYER BECOMES MORE SHALLOW. IF THE STRATUS
LOWERS ENOUGH...MAY END UP WITH AREAS OF DENSE FOG AS WELL...SO WILL
HAVE TO MONITOR THAT. THINKING THE IFR STRATUS DOES EVENTUALLY MOVE
BACK INTO KHON WITH SOUTHEASTERLY WINDS ADVECTING IT BACK IN. EXPECT
THE STRATUS TO BURN OFF AFTER SUNSET...WITH VFR CONDITIONS BECOMING
DOMINATE BY MID TO LATE MORNING AT THE TAF SITES. BREEZY SOUTHERLY
WINDS ARE LIKELY TOMORROW AS WELL...WITH GUSTS UP TO 25 KTS BY
AFTERNOON.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...08
SHORT TERM...MJ
LONG TERM...CHAPMAN
AVIATION...CHENARD
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
345 PM CDT MON SEP 16 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 344 PM CDT MON SEP 16 2013
STRATOCUMULUS FIELD REMAINS FAIRLY WIDESPREAD ACROSS THE WESTERN AND
SOUTHERN PORTIONS OF THE CWA AT MID AFTERNOON...WITH INVERSION EVIDENT
IN MORNING KOAX RAOB DUCTING THE CLOUD FIELD ON INCREASING SOUTHERLY
COMPONENT TO LOW LEVEL WINDS. DRIER AIR TO THE NORTH HAS ALLOWED
EARLIER CLOUDS TO REFORM HIGHER THEN MIX OUT...MAINLY CLEAR ALONG
THE NORTHERN TIER AND THROUGH THE MID TO LOWER JAMES VALLEY. WITH
CONTINUED EAST/SOUTHEAST TRAJECTORY AND CELLULAR NATURE...SHOULD SEE
A DECREASE IN CLOUD COVERAGE INTO EARLY EVENING.
AREA OF SHOWERS CURRENTLY ONGOING ACROSS NORTHERN KANSAS AND FAR
SOUTHERN NEBRASKA...AND FORCING ASSOCIATED WITH THIS LOOKS TO MAKE A
BEELINE TOWARD OUR SOUTHEAST CWA STARTING AFTER 06Z. WITH TIMING OF
INCREASE IN THETA E ADVECTION AHEAD OF WAVE LIFTING EAST/NORTHEAST
FROM SOUTHWEST NEBRASKA/NORTHWEST KANSAS...WILL MENTION SCATTERED
SHOWERS...WITH MAIN PV FORCING SLIPPING JUST TO THE SOUTH. AGAIN
NOT A GREAT DEAL OF INSTABILITY...EVEN ELEVATED...AS LOW LEVEL JET
INCREASES TONIGHT. LIKELY THAT A BULK OF THE PRECIPITATION SHOULD
END IN THE EAST BY 18Z TO 20Z AS THE MID LEVEL WAVE PASSES...BUT
THERE IS A PERSISTENT LOWER TO MID LEVEL THETA-E ADVECTION. PRETTY
CAPPED TO SURFACE BASED ACTIVITY...BUT COULD SEE AN ISOLATED SHOWER
OR EVEN RUMBLE OF THUNDER BY MID TO LATE AFTERNOON ACROSS THE
SOUTHEAST THIRD OF THE AREA. DID NOT EXPLICITLY MENTION...BUT
MAY HAVE SOME ISSUES WITH DRIZZLE WELL BACK WESTWARD OF I29 DURING
THE MORNING TO MIDDAY HOURS. IN FACT...LOWER LEVELS CONTINUE TO
INDICATE INVERSION WHICH MAY YIELD TOUGHER THAN EXPECTED EROSION OF
LOWER CLOUDS...WHICH ARE NOTORIOUSLY HANDLED POORLY BY MODELS. DID
LOWER MAX TEMPS IN RESPONSE TO THE EXPECTED WIDESPREAD STRATUS...
LEAVING EXTREME WEST WITH A CHANCE TO REACH MID TO UPPER 70S.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 344 PM CDT MON SEP 16 2013
TOUGH CALL ON POPS TUESDAY NIGHT WITH INSTABILITY AND HEIGHTS TRYING
TO BUILD ACROSS THE EASTERN HALF OF THE FORECAST AREA. MOST UNSTABLE
CAPE PEAKS OUT AROUND 1800 J/KG IN THE NAM...AND WITH MODERATE
WAA/THETAE ADVECTION CONTINUING ALOFT COULD SEE SOME THUNDERSTORMS
IN THE EAST. QUESTIONS REMAIN AS TO WHETHER CONVECTION WILL GET
GOING WITH LACK OF STRONG UPPER LEVEL SUPPORT ACROSS THE AREA...SO
HAVE LEFT POPS IN THE CHANCE RANGE THROUGH THE OVERNIGHT. WITH A
BREEZY SOUTH WINDS...TEMPERATURES SHOULD BE SLOW TO FALL THROUGH THE
OVERNIGHT.
BREEZY SOUTH WINDS CONTINUE ON WEDNESDAY AS STRONG SURFACE WARM
FRONT LIFTS THROUGH THE AREA. AS THE FRONT MOVES THROUGH THE
AREA...SOUNDINGS SUGGEST SKIES WILL CLEAR AND BOUNDARY LAYER WILL
BECOME QUITE DEEP THROUGH THE DAY. NAM MIXES TO NEAR 700 MB WHICH
RESULTS IN RECORD HIGHS IN THE 90S. HAVE NOT SIDED WITH AS MUCH
MIXING AND INSTEAD WENT WITH FORECAST HIGHS CLOSE TO 850 HPA MIX OUT
WHICH IS STILL 15-20 DEGREES ABOVE NORMAL.
SURFACE COLD FRONT IS EXPECTED TO MOVE THROUGH THE REGION WEDNESDAY
NIGHT INTO THURSDAY. UPPER WAVE LINGERS WELL BEHIND THE SURFACE
FRONT...AND WELL TO THE NORTH AND QUESTION BECOMES WHETHER
ATMOSPHERE WILL BE ABLE TO GET AROUND THE CAP TO PRODUCE
THUNDERSTORMS. HAVE PLACED FOCUS OF CHANCE POPS CLOSER TO THE MID
LEVEL WAVE ALONG AND NORTH OF I-90...BUT EVEN THEN...CONVECTION MAY
STILL BE FOCUSED FURTHER TO THE NORTH CLOSER TO THE MID-LEVEL WAVE.
SURFACE HIGH PRESSURE DOMINATES ACROSS THE REGION FRIDAY INTO
SATURDAY LEADING TO EARLY FALL CONDITIONS WITH NEAR NORMAL
TEMPERATURES. APPEARS AS THOUGH WARM FRONT WILL LIFT THROUGH THE
AREA SUNDAY MORNING ASSOCIATED WITH DEEPENING UPPER LEVEL TROUGH.
POPS HAVE REALLY BEEN THROTTLED BACK WITH PASSAGE OF THE WARM FRONT
ON SUNDAY...WITH RELATIVELY STRONG SOUTHERLY FLOW CONTINUING INTO
MONDAY AHEAD OF THE NEXT COLD FRONT TO MOVE THROUGH THE AREA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1254 PM CDT MON SEP 16 2013
WIDESPREAD CEILINGS ACROSS ALL BUT PARTS OF SW MN AT MIDDAY. MOST
OF THE NORTHEAST FLANK FEATURES SOMEWHAT MORE SHALLOW MOISTURE
PROFILE WITH MIXING DISSIPATING NORTHEAST FLANK OF CLOUDS...WHILE
FARTHER SOUTHWEST HAVE SEEN DEVELOPMENT OF BROKEN TO OVERCAST
CEILINGS WITH DIURNAL HEATING...SUPPORTED WELL ON MORNING 12Z KOAX
RAOB. LIKELY THAT EASTERLY TRAJECTORY WILL AID IN AT LEAST BKN-SCT
CEILINGS...AND MAINLY VFR HEIGHTS FOR THE AFTERNOON AND EARLY
EVENING. RAP IS ABOUT THE ONLY MODELS WHICH IS PROFICIENT IN
PREDICTING THE CLOUD COVERAGE POTENTIAL...AND SUGGESTS THAT
INCREASING SOUTHEASTERLY TRAJECTORY WILL PULL STRATUS ANEW INTO
THE AREA BY LATER EVENING...WITH DEVELOPMENT OF WIDESPREAD MVFR
CEILINGS. WILL ALSO BE POSSIBILITY FOR A FEW SHOWERS BETWEEN 08Z
AND 14Z IN KSUX AREA. WITH STRATUS HOLDING IN DUE TO SOUTHERLY LOW
LEVEL FLOW AND INVERSION...SOME CONCERN THAT MIGHT BE THREAT FOR
DRIZZLE/FOG REDUCING VISIBILITIES FARTHER TO THE NORTHWEST...
INCLUDING KFSD AREA DURING THE MORNING HOURS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...CHAPMAN
LONG TERM...
AVIATION...CHAPMAN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1254 PM CDT MON SEP 16 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 303 AM CDT MON SEP 16 2013
LOW LEVEL MOISTURE PATTERN IS A BIT CHAOTIC EARLY THIS MORNING
WITH AREAS OF LOW CLOUDS...BUT NOT LOW STRATUS...DEVELOPING AND
MOVING ACROSS THE AREA. THIS IS HAPPENING EVEN AS THE MORE SOLID
DECK HAS BEEN DECREASING FAR SOUTH OVER THE MISSOURI RIVER AREA.
SHORT TERM MODELS ESPECIALLY THE HRRR SEEM TO HAVE A HANDLE ON
THIS. THAT MODEL SHOWS THIS PATTERN CONTINUING THEN THE CLOUDS
DECREASING FAIRLY QUICKLY AROUND NOON. WILL GO WITH THIS IDEA AS
THE AIR GETS HEATED AND MIXED OUT. THAT SHOULD MAKE SKIES MOSTLY
SUNNY BY THE AFTERNOON. A SPLIT BETWEEN GUIDANCE AND CONTINUITY
LOOKS GOOD ON HIGH TEMPERATURES TODAY. TONIGHT THEN STARTS THE
WARM ADVECTION PATTERN OVER A DEEP RANGE OF LEVELS AND THE
ACCOMPANYING INCREASE IN CLOUDS FROM THE SOUTH...ESPECIALLY OVER
THE EASTERN PART OF THE AREA. LOW TEMPERATURES TONIGHT WILL NOT BE
AS COOL AS CURRENT VALUES. THE START OF AN INCREASE IN INSTABILITY
DOES NOT SEEM ENOUGH TO SUPPORT ANY SHOWERS OR STORMS THROUGH
TONIGHT...OR 12Z TUESDAY.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 303 AM CDT MON SEP 16 2013
THE CLOUD INCREASE IN THE WARM ADVECTION PATTERN WILL CONTINUE TO
EVOLVE TUESDAY AND SKIES SHOULD BECOME CLOUDY OR MOSTLY
CLOUDY...ESPECIALLY IN THE EAST. MEANWHILE...INSTABILITY CONTINUES
TO SLOWLY INCREASE BUT MAY BE LIMITED BY THE COPIOUS MOISTURE
ADVECTING IN...AND SUPPORT FOR SHOWERS AND STORMS IS OTHERWISE
QUITE MARGINAL. NEVERTHELESS...WITH MOISTURE INCREASING AT MOST
LEVELS...IT WOULD NOT TAKE MUCH FOR A FEW SHOWERS TO DEVELOP IN
OUR IOWA...MINNESOTA...AND EXTREME SOUTHEAST SD ZONES EVEN IF
THUNDERSTORMS HOLD OFF. WILL MENTION CHANCE OF SHOWERS AND
ISOLATED THUNDER. THIS SHOULD CONTINUE INTO TUESDAY NIGHT BUT
START TO MOVE SLOWLY EAST AND OUT OF THE AREA BY THE START OF
WEDNESDAY AS STRONG WARMING BEGINS TO OUTPACE THE MOISTURE...AND
RELATIVE HUMIDITIES AND CLOUD COVER DROPS OFF. TEMPERATURES WILL
BE WARMER TUESDAY BUT HELD DOWN SOME BY THE CLOUD COVER ESPECIALLY
EAST...THEN TUESDAY NIGHT SHOULD BE QUITE A BIT WARMER.
WEDNESDAY LOOK STILL SET TO BE A MUCH WARMER DAY WITH PLENTY OF
SUNSHINE. THE THREAT OF SHOWERS AND STORMS SHOULD HOLD OFF UNTIL
WEDNESDAY NIGHT WHEN THE COLD FRONT ENTERS THE AREA. HIGHS SHOULD
BE IN THE 80S WITH TEMPERATURES LIKELY REACHING A BIT ABOVE
GUIDANCE VALUES...AND WEDNESDAY NIGHT SHOULD BE WARM AGAIN AS THE
FRONT GETS INTO THE AREA.
FAIRLY POTENT FRONT TRACKS THROUGH THE EASTERN HALF OF THE
FORECAST AREA THURSDAY MORNING. ANY ONGOING SCATTERED SHOWERS AND
THUNDERSTORMS ALONG AND AHEAD OF THE FRONT WILL TRACK EASTWARD
AND SHOULD DIMINISH BY LATE AFTERNOON. NORTHWEST WINDS WILL BE
BREEZY BEHIND THE FRONT AND PROVIDE A DECENT SHOT OF COLD AIR
ADVECTION THURSDAY NIGHT AND FRIDAY. LOWS WILL DIP INTO THE LOWER
50S ON THURSDAY AND AS COLD AS THE MID 40S FRIDAY NIGHT. WITH A
GENERAL UPPER LEVEL NORTHWEST FLOW PATTERN IN PLACE THROUGH THE
END OF THE WEEK...THE WEATHER WILL REMAIN DRY WITH HIGHS NEAR OR
JUST BELOW SEASONAL NORMALS. RIDGING OVER THE INTERMOUNTAIN WEST
SHIFTS EASTWARD INTO THE HIGH PLAINS FRIDAY NIGHT WITH THE AXIS
MOVING OVERHEAD SATURDAY NIGHT. WITH SOUTHERLY FLOW INCREASING ON
SUNDAY...TEMPERATURES WILL WARM BACK INTO THE MID 70S TO NEAR
80...BUT MAY ALSO BRING THE NEXT POTENTIAL FOR SHOWERS AND
THUNDERSTORMS. MODELS A BIT UNCERTAIN ON TIMING...BUT WILL LEAVE
LOW END CHANCES SUNDAY AND SUNDAY NIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1254 PM CDT MON SEP 16 2013
WIDESPREAD CEILINGS ACROSS ALL BUT PARTS OF SW MN AT MIDDAY. MOST
OF THE NORTHEAST FLANK FEATURES SOMEWHAT MORE SHALLOW MOISTURE
PROFILE WITH MIXING DISSIPATING NORTHEAST FLANK OF CLOUDS...WHILE
FARTHER SOUTHWEST HAVE SEEN DEVELOPMENT OF BROKEN TO OVERCAST
CEILINGS WITH DIURNAL HEATING...SUPPORTED WELL ON MORNING 12Z KOAX
RAOB. LIKELY THAT EASTERLY TRAJECTORY WILL AID IN AT LEAST BKN-SCT
CEILINGS...AND MAINLY VFR HEIGHTS FOR THE AFTERNOON AND EARLY
EVENING. RAP IS ABOUT THE ONLY MODELS WHICH IS PROFICIENT IN
PREDICTING THE CLOUD COVERAGE POTENTIAL...AND SUGGESTS THAT
INCREASING SOUTHEASTERLY TRAJECTORY WILL PULL STRATUS ANEW INTO
THE AREA BY LATER EVENING...WITH DEVELOPMENT OF WIDESPREAD MVFR
CEILINGS. WILL ALSO BE POSSIBILITY FOR A FEW SHOWERS BETWEEN 08Z
AND 14Z IN KSUX AREA. WITH STRATUS HOLDING IN DUE TO SOUTHERLY LOW
LEVEL FLOW AND INVERSION...SOME CONCERN THAT MIGHT BE THREAT FOR
DRIZZLE/FOG REDUCING VISIBILITIES FARTHER TO THE NORTHWEST...
INCLUDING KFSD AREA DURING THE MORNING HOURS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...
AVIATION...CHAPMAN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
633 AM CDT MON SEP 16 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 303 AM CDT MON SEP 16 2013
LOW LEVEL MOISTURE PATTERN IS A BIT CHAOTIC EARLY THIS MORNING
WITH AREAS OF LOW CLOUDS...BUT NOT LOW STRATUS...DEVELOPING AND
MOVING ACROSS THE AREA. THIS IS HAPPENING EVEN AS THE MORE SOLID
DECK HAS BEEN DECREASING FAR SOUTH OVER THE MISSOURI RIVER AREA.
SHORT TERM MODELS ESPECIALLY THE HRRR SEEM TO HAVE A HANDLE ON
THIS. THAT MODEL SHOWS THIS PATTERN CONTINUING THEN THE CLOUDS
DECREASING FAIRLY QUICKLY AROUND NOON. WILL GO WITH THIS IDEA AS
THE AIR GETS HEATED AND MIXED OUT. THAT SHOULD MAKE SKIES MOSTLY
SUNNY BY THE AFTERNOON. A SPLIT BETWEEN GUIDANCE AND CONTINUITY
LOOKS GOOD ON HIGH TEMPERATURES TODAY. TONIGHT THEN STARTS THE
WARM ADVECTION PATTERN OVER A DEEP RANGE OF LEVELS AND THE
ACCOMPANYING INCREASE IN CLOUDS FROM THE SOUTH...ESPECIALLY OVER
THE EASTERN PART OF THE AREA. LOW TEMPERATURES TONIGHT WILL NOT BE
AS COOL AS CURRENT VALUES. THE START OF AN INCREASE IN INSTABILITY
DOES NOT SEEM ENOUGH TO SUPPORT ANY SHOWERS OR STORMS THROUGH
TONIGHT...OR 12Z TUESDAY.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 303 AM CDT MON SEP 16 2013
THE CLOUD INCREASE IN THE WARM ADVECTION PATTERN WILL CONTINUE TO
EVOLVE TUESDAY AND SKIES SHOULD BECOME CLOUDY OR MOSTLY
CLOUDY...ESPECIALLY IN THE EAST. MEANWHILE...INSTABILITY CONTINUES
TO SLOWLY INCREASE BUT MAY BE LIMITED BY THE COPIOUS MOISTURE
ADVECTING IN...AND SUPPORT FOR SHOWERS AND STORMS IS OTHERWISE
QUITE MARGINAL. NEVERTHELESS...WITH MOISTURE INCREASING AT MOST
LEVELS...IT WOULD NOT TAKE MUCH FOR A FEW SHOWERS TO DEVELOP IN
OUR IOWA...MINNESOTA...AND EXTREME SOUTHEAST SD ZONES EVEN IF
THUNDERSTORMS HOLD OFF. WILL MENTION CHANCE OF SHOWERS AND
ISOLATED THUNDER. THIS SHOULD CONTINUE INTO TUESDAY NIGHT BUT
START TO MOVE SLOWLY EAST AND OUT OF THE AREA BY THE START OF
WEDNESDAY AS STRONG WARMING BEGINS TO OUTPACE THE MOISTURE...AND
RELATIVE HUMIDITIES AND CLOUD COVER DROPS OFF. TEMPERATURES WILL
BE WARMER TUESDAY BUT HELD DOWN SOME BY THE CLOUD COVER ESPECIALLY
EAST...THEN TUESDAY NIGHT SHOULD BE QUITE A BIT WARMER.
WEDNESDAY LOOK STILL SET TO BE A MUCH WARMER DAY WITH PLENTY OF
SUNSHINE. THE THREAT OF SHOWERS AND STORMS SHOULD HOLD OFF UNTIL
WEDNESDAY NIGHT WHEN THE COLD FRONT ENTERS THE AREA. HIGHS SHOULD
BE IN THE 80S WITH TEMPERATURES LIKELY REACHING A BIT ABOVE
GUIDANCE VALUES...AND WEDNESDAY NIGHT SHOULD BE WARM AGAIN AS THE
FRONT GETS INTO THE AREA.
FAIRLY POTENT FRONT TRACKS THROUGH THE EASTERN HALF OF THE
FORECAST AREA THURSDAY MORNING. ANY ONGOING SCATTERED SHOWERS AND
THUNDERSTORMS ALONG AND AHEAD OF THE FRONT WILL TRACK EASTWARD
AND SHOULD DIMINISH BY LATE AFTERNOON. NORTHWEST WINDS WILL BE
BREEZY BEHIND THE FRONT AND PROVIDE A DECENT SHOT OF COLD AIR
ADVECTION THURSDAY NIGHT AND FRIDAY. LOWS WILL DIP INTO THE LOWER
50S ON THURSDAY AND AS COLD AS THE MID 40S FRIDAY NIGHT. WITH A
GENERAL UPPER LEVEL NORTHWEST FLOW PATTERN IN PLACE THROUGH THE
END OF THE WEEK...THE WEATHER WILL REMAIN DRY WITH HIGHS NEAR OR
JUST BELOW SEASONAL NORMALS. RIDGING OVER THE INTERMOUNTAIN WEST
SHIFTS EASTWARD INTO THE HIGH PLAINS FRIDAY NIGHT WITH THE AXIS
MOVING OVERHEAD SATURDAY NIGHT. WITH SOUTHERLY FLOW INCREASING ON
SUNDAY...TEMPERATURES WILL WARM BACK INTO THE MID 70S TO NEAR
80...BUT MAY ALSO BRING THE NEXT POTENTIAL FOR SHOWERS AND
THUNDERSTORMS. MODELS A BIT UNCERTAIN ON TIMING...BUT WILL LEAVE
LOW END CHANCES SUNDAY AND SUNDAY NIGHT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 623 AM CDT MON SEP 16 2013
STRATUS DECK AND PATCHY FOG REMAINS THE MAIN CONCERN THIS MORNING.
EXPECT THE PATCHY FOG...WHICH HAS DEVELOPED IN AREAS NOT BLANKETED IN
STATUS...TO QUICKLY DISSIPATE BY 14Z. STRATUS HAS BEEN HOVERING
AROUND 3000 TO 4500 FEET AND IS ADVECTING NORTHWARD AND EXPANDING IN
AREA. THIS STRATUS WILL LIKELY CONTINUE LIFTING NORTH NORTHWWARD
THROUGH MUCH OF THE MORNING...BUT SHOULD BEGIN TO ERRODE FROM AROUND
17Z THROUGH 00Z. COULD SEE SOME BRIEF CEILING DIPS TO MVFR
LEVELS...BUT OVERALL SHOULD REMAINS LOW END VFR. THIS LAYER MAY BUILD
NORTHEASTWARD...REDEVELOPING NEAR THE MISSOURI VALLEY AND AFTER 06Z.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...
AVIATION...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
303 AM CDT MON SEP 16 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 303 AM CDT MON SEP 16 2013
LOW LEVEL MOISTURE PATTERN IS A BIT CHAOTIC EARLY THIS MORNING
WITH AREAS OF LOW CLOUDS...BUT NOT LOW STRATUS...DEVELOPING AND
MOVING ACROSS THE AREA. THIS IS HAPPENING EVEN AS THE MORE SOLID
DECK HAS BEEN DECREASING FAR SOUTH OVER THE MISSOURI RIVER AREA.
SHORT TERM MODELS ESPECIALLY THE HRRR SEEM TO HAVE A HANDLE ON
THIS. THAT MODEL SHOWS THIS PATTERN CONTINUING THEN THE CLOUDS
DECREASING FAIRLY QUICKLY AROUND NOON. WILL GO WITH THIS IDEA AS
THE AIR GETS HEATED AND MIXED OUT. THAT SHOULD MAKE SKIES MOSTLY
SUNNY BY THE AFTERNOON. A SPLIT BETWEEN GUIDANCE AND CONTINUITY
LOOKS GOOD ON HIGH TEMPERATURES TODAY. TONIGHT THEN STARTS THE
WARM ADVECTION PATTERN OVER A DEEP RANGE OF LEVELS AND THE
ACCOMPANYING INCREASE IN CLOUDS FROM THE SOUTH...ESPECIALLY OVER
THE EASTERN PART OF THE AREA. LOW TEMPERATURES TONIGHT WILL NOT BE
AS COOL AS CURRENT VALUES. THE START OF AN INCREASE IN INSTABILITY
DOES NOT SEEM ENOUGH TO SUPPORT ANY SHOWERS OR STORMS THROUGH
TONIGHT...OR 12Z TUESDAY.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 303 AM CDT MON SEP 16 2013
THE CLOUD INCREASE IN THE WARM ADVECTION PATTERN WILL CONTINUE TO
EVOLVE TUESDAY AND SKIES SHOULD BECOME CLOUDY OR MOSTLY
CLOUDY...ESPECIALLY IN THE EAST. MEANWHILE...INSTABILITY CONTINUES
TO SLOWLY INCREASE BUT MAY BE LIMITED BY THE COPIOUS MOISTURE
ADVECTING IN...AND SUPPORT FOR SHOWERS AND STORMS IS OTHERWISE
QUITE MARGINAL. NEVERTHELESS...WITH MOISTURE INCREASING AT MOST
LEVELS...IT WOULD NOT TAKE MUCH FOR A FEW SHOWERS TO DEVELOP IN
OUR IOWA...MINNESOTA...AND EXTREME SOUTHEAST SD ZONES EVEN IF
THUNDERSTORMS HOLD OFF. WILL MENTION CHANCE OF SHOWERS AND
ISOLATED THUNDER. THIS SHOULD CONTINUE INTO TUESDAY NIGHT BUT
START TO MOVE SLOWLY EAST AND OUT OF THE AREA BY THE START OF
WEDNESDAY AS STRONG WARMING BEGINS TO OUTPACE THE MOISTURE...AND
RELATIVE HUMIDITIES AND CLOUD COVER DROPS OFF. TEMPERATURES WILL
BE WARMER TUESDAY BUT HELD DOWN SOME BY THE CLOUD COVER ESPECIALLY
EAST...THEN TUESDAY NIGHT SHOULD BE QUITE A BIT WARMER.
WEDNESDAY LOOK STILL SET TO BE A MUCH WARMER DAY WITH PLENTY OF
SUNSHINE. THE THREAT OF SHOWERS AND STORMS SHOULD HOLD OFF UNTIL
WEDNESDAY NIGHT WHEN THE COLD FRONT ENTERS THE AREA. HIGHS SHOULD
BE IN THE 80S WITH TEMPERATURES LIKELY REACHING A BIT ABOVE
GUIDANCE VALUES...AND WEDNESDAY NIGHT SHOULD BE WARM AGAIN AS THE
FRONT GETS INTO THE AREA.
FAIRLY POTENT FRONT TRACKS THROUGH THE EASTERN HALF OF THE
FORECAST AREA THURSDAY MORNING. ANY ONGOING SCATTERED SHOWERS AND
THUNDERSTORMS ALONG AND AHEAD OF THE FRONT WILL TRACK EASTWARD
AND SHOULD DIMINISH BY LATE AFTERNOON. NORTHWEST WINDS WILL BE
BREEZY BEHIND THE FRONT AND PROVIDE A DECENT SHOT OF COLD AIR
ADVECTION THURSDAY NIGHT AND FRIDAY. LOWS WILL DIP INTO THE LOWER
50S ON THURSDAY AND AS COLD AS THE MID 40S FRIDAY NIGHT. WITH A
GENERAL UPPER LEVEL NORTHWEST FLOW PATTERN IN PLACE THROUGH THE
END OF THE WEEK...THE WEATHER WILL REMAIN DRY WITH HIGHS NEAR OR
JUST BELOW SEASONAL NORMALS. RIDGING OVER THE INTERMOUNTAIN WEST
SHIFTS EASTWARD INTO THE HIGH PLAINS FRIDAY NIGHT WITH THE AXIS
MOVING OVERHEAD SATURDAY NIGHT. WITH SOUTHERLY FLOW INCREASING ON
SUNDAY...TEMPERATURES WILL WARM BACK INTO THE MID 70S TO NEAR
80...BUT MAY ALSO BRING THE NEXT POTENTIAL FOR SHOWERS AND
THUNDERSTORMS. MODELS A BIT UNCERTAIN ON TIMING...BUT WILL LEAVE
LOW END CHANCES SUNDAY AND SUNDAY NIGHT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1023 PM CDT SUN SEP 15 2013
DRYING FROM THE NORTH HAS REALLY TAKEN OVER SO WILL CONTINUE THE
TREND OF VFR AT KHON AND KFSD. KSUX STILL ON THE EDGE AND IF THEY
ARE NEAR THE EDGE OF THE STRATUS FIELD WHERE THE COOLER AIR IS
MIXING WITH THE REMAINING LOW LEVEL MOISTURE SOME FOG COULD
DEVELOP SO DID INTRODUCE SOME MVFR VISIBILITIES FOR A COUPLE OF
HOURS AROUND SUNRISE AT KSUX. OTHERWISE WILL SEE A SOUTHEAST WIND
INCREASE THROUGH THE PERIOD AND WILL SEE A SMALL THREAT FOR LLWS
AFTER ABOUT 4Z/17.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...
AVIATION...08
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1154 AM CDT MON SEP 16 2013
.AVIATION...
AN OUTFLOW BOUNDARY THAT EXTENDED FROM JUST NORTH OF KGLE
/GAINESVILLE/ AND KRPH /GRAHAM/ TO 30 MILES WEST OF KABI
/ABILENE/ AT 1650Z WILL CONTINUE TO MOVE SOUTHEAST AT NEAR 10
KNOTS THROUGH LATE AFTERNOON. ISOLATED SHOWERS HAVE DEVELOPED
ALONG THIS BOUNDARY AND SCATTERED SHOWERS AND THUNDERSTORMS ARE
EXPECTED NEAR THIS BOUNDARY THIS AFTERNOON. ISOLATED SHOWERS AND
THUNDERSTORMS ARE POSSIBLE ACROSS THE REST OF NORTH AND CENTRAL
TEXAS. FOR THE METROPLEX TAFS...HAVE PLACED VCTS IN THE TAFS FOR
THE 20Z-01Z PERIOD WITH A WIND SHIFT TO THE NORTH AT 20Z WITH THE
OUTFLOW BOUNDARY. WINDS SHOULD COME BACK AROUND TO THE EAST BY
01Z.
IN WACO...VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE
FORECAST PERIOD. AN ISOLATED SHOWER OR THUNDERSTORM IS POSSIBLE
LATE AFTERNOON THROUGH SUNSET...BUT THE CHANCES AT THE AIRPORT IS
TOO LOW TO INCLUDE IN THE TAF AT THIS TIME.
58
&&
.UPDATE...
LOCAL 15Z SURFACE ANALYSIS SHOWS A COLD FRONT IN NORTHERN OKLAHOMA
WITH CONVECTION ONGOING IN CLOSE PROXIMITY TO THE FRONT. AN OUTFLOW
BOUNDARY HAS SURGED SOUTH OVERNIGHT AND THE BOUNDARY IS JUST
ENTERING OUR NORTHWESTERN ZONES. THE MOVEMENT HAS SLOWED DOWN AS
HEATING HAS COMMENCED...BUT DO EXPECT A CONTINUED MOVEMENT THIS
MORNING. THIS BOUNDARY WILL LIKELY SERVE AS A MECHANISM FOR
SHOWERS AND THUNDERSTORM DEVELOPMENT THIS AFTERNOON ACROSS THE
NORTHERN HALF OF THE FORECAST AREA. CURRENT POP CONFIGURATION
LOOKS GOOD AND WILL MAKE NO CHANGES AT THIS TIME. NOT EXPECTING
SEVERE WEATHER AS CAPE VALUES REMAIN LESS THAN 1500 J/KG AND
SURFACE DEWPOINTS IN THE UPPER 60S SHOULD PREVENT DOWNBURST WINDS.
HOWEVER...A STRONG STORM IS POSSIBLE WITH GUSTY WINDS UP TO 50
MPH.
HAMPSHIRE
&&
.PREV DISCUSSION... /ISSUED 408 AM CDT MON SEP 16 2013/
EARLY MORNING WATER VAPOR SATELLITE IMAGERY SHOWED AN EXTENSIVE
PLUME OF TROPICAL MOISTURE OVER CENTRAL MEXICO DUE TO TROPICAL
DEPRESSION MANUEL MOVING ONSHORE THE WEST CENTRAL MEXICAN COAST. A
SECONDARY TROPICAL PLUME OF MOISTURE ASSOCIATED WITH HURRICANE
INGRID REMAINED JUST OFF SHORE OF THE NORTHEAST MEXICAN COAST.
ACROSS THE CONUS...A STRONG UPPER LEVEL TROUGH CONTINUED TO MOVE
SOUTHEAST OVER THE GREAT LAKES REGION TOWARDS THE EAST COAST. THE
SUBTROPICAL RIDGING THAT HAD BEEN DOMINATING THE PLAINS HAD BEEN
FLATTENED AND TILTED OVER THE SOUTHEASTERN UNITED STATES IN
RESPONSE TO THE PASSAGE OF THE STRONG NORTHERN STREAM TROUGH. THIS
LEFT GENERALLY WEAK WESTERLY FLOW OVER THE CENTRAL AND SOUTH
PLAINS THIS MORNING. A WEAK SHORTWAVE TROUGH WAS OBSERVED OVER THE
TX AND OK PANHANDLES...MOVING SLOWLY EAST ALONG A NEARLY STALLED
OUT COLD FRONT.
REGIONAL RADARS SHOWED A LARGE CLUSTER OF SHOWERS AND THUNDERSTORMS
ASSOCIATED WITH THE FRONT AND SHORTWAVE TROUGH AT 0830Z OR 330 AM
EXTENDING FROM AMARILLO TO NORTH CENTRAL OK. KFDR RADAR WAS
TRACKING A CONSOLIDATED OUTFLOW BOUNDARY THAT WAS MOVING SOUTHEAST
AWAY FROM THESE SHOWERS AND STORMS TOWARDS NORTH TEXAS.
TODAY...THE RAP AND THE NAM BOTH BOTH INDICATE THAT THE
CONSOLIDATED OUTFLOW BOUNDARY MOVING TOWARDS NORTH TEXAS EARLY
THIS MORNING WILL CONTINUE SOUTHEAST INTO THE CWA JUST AFTER
SUNRISE. THIS BOUNDARY WILL LIKELY STALL OUT SOMEWHERE NORTHWEST
OF THE DFW METROPLEX...WITH THE LATEST GUIDANCE SUGGESTING THE
BOUNDARY WILL COME TO REST NEAR A GAINESVILLE TO WEATHERFORD TO
CISCO LINE BY LATE THIS MORNING. LOCATIONS NEAR AND NORTHWEST OF
THE BOUNDARY WILL LIKELY SEE SOME ISOLATED TO SCATTERED RAIN
SHOWERS AND THUNDERSTORMS DEVELOP BY THE EARLY AFTERNOON HOURS OF
THE DAY. THIS IS PRIMARILY DUE TO THE FACT THAT THERE IS AMPLE
LOW-LEVEL MOISTURE IN PLACE TO SUPPORT PRECIPITATION...WITH THE
FRONT ACTING AS A LIFTING MECHANISM IN AN ENVIRONMENT
CHARACTERIZED WITH LITTLE TO NO CAPPING INVERSION ALOFT. WENT
AHEAD WITH A 30 PERCENT CHANCE OF RAIN FOR THESE LOCATIONS AS A
RESULT...INCLUDING MUCH OF THE DFW AREA.
ELSEWHERE ACROSS NORTH AND CENTRAL TEXAS...THE THERMODYNAMIC
ENVIRONMENT WILL BE NEARLY EQUIVALENT TO LOCATIONS NEAR THE
OUTFLOW BOUNDARY...BUT THERE IS NO OBVIOUS LIFTING MECHANISM TO
SUPPORT THE INITIATION OF SHOWERS AND STORMS THIS AFTERNOON.
DURING THE PEAK HEATING HOURS OF THE DAY...THE BUOYANCY FORCE WILL
BE MAXIMIZED...AND ISOLATED SHOWERS AND STORMS MAY DEVELOP
ANYWHERE ACROSS THE CWA AS A RESULT. MOST PRECIPITATION SHOULD
REMAIN TIED TO DAYTIME HEATING TODAY...THEREFORE WENT AHEAD AND
KEPT A MENTION OF SHOWERS AND STORMS IN THE FORECAST ONLY THROUGH
03Z THIS EVENING.
HEATING IS A BIT OF A CONCERN TODAY BECAUSE WE HAVE EXTENSIVE
CLOUD COVER IN THE FORM OF CIRRUS CLOUDS OVER THE REGION. THESE
CLOUDS MAY BREAK UP A BIT THROUGHOUT THE DAY...BUT WE WILL NEVER
BE FULLY RID OF THEM. REGARDLESS...AT 3 AM REGIONAL TEMPERATURES
WERE HOLDING IN THE MID TO UPPER 70S FOR MOST LOCATIONS. SO
DESPITE PERSISTENT CIRRUS CLOUDS TO CONTEND WITH...A 15 TO 20
DEGREE TEMPERATURE INCREASE SHOULD BE EASY TO ATTAIN BRINGING MOST
LOCATIONS UP INTO THE MID 90S FOR HIGHS WHICH IS WARM ENOUGH TO
SUPPORT ISOLATED STORMS IN THE FORECAST.
CONCERNING THE REMNANTS OF INGRID AND MANUEL...WITH THE
SUBTROPICAL RIDGE FLATTENED OUT...ITS CENTER OF CIRCULATION IS
EXPECTED TO SET UP ANYWHERE FROM SOUTHEAST TX TO THE MISSISSIPPI
COAST THROUGH THIS PERIOD. THE EXACT POSITION OF THIS RIDGE WILL
PLAY A LARGE ROLE IN TROPOSPHERIC STEERING FLOW/TRAJECTORIES FOR
TROPICAL MOISTURE INTO NORTH TX THROUGHOUT THE WEEK HEADED INTO
THIS WEEKEND. IF THE SUBTROPICAL RIDGE SETS UP FURTHER EAST...DEEP
TROPOSPHERIC FLOW WOULD FAVOR TRANSPORTING THE COMBINED MOISTURE
PLUMES FROM MANUEL AND INGRID FROM NORTHERN MEXICO INTO NORTH TX
BY LATE THIS WEEK. IF THE RIDGE SETS UP FURTHER WEST...THE MID AND
UPPER LEVEL TROPICAL MOISTURE WILL BE SHUNTED WEST AWAY FROM
TEXAS. UNFORTUNATELY MODELS REMAIN INCONSISTENT WITH REGARDS TO
THIS SOLUTION...SO DID NOT MAKE ANY HUGE ADJUSTMENTS TO THE
PREVIOUS FORECAST AT THIS TIME.
IN GENERAL...CONTINUE TO CARRY LOW POPS/RAIN CHANCES FROM TUESDAY
THROUGH THURSDAY...BECOMING MORE CONFIDENT AND WIDESPREAD WITH
RAIN CHANCES FOR FRIDAY AND SATURDAY BEFORE RETURNING TO A DRY
FORECAST ON SUNDAY. FOR MORE DETAILS READ ON...
TUESDAY THROUGH THURSDAY...REGARDLESS OF WHAT HAPPENS WITH THE
TROPICAL MOISTURE PLUME FROM THE MEXICAN TROPICAL CYCLONES...THE
MOST IMPORTANT THING TO WATCH DURING THIS TIME FRAME IS THE
DIRECTION OF LOW LEVEL WINDS. LOOKING AT THE 850 MB LEVEL...WINDS
THAT REMAIN EASTERLY NEAR THE GULF COAST WILL PREVENT RICH LOW-
LEVEL MOISTURE FROM MAKING ITS WAY NORTH INTO NORTH TX WHILE
SOUTHEASTERLY WINDS WILL SEND THIS MOISTURE RIGHT UP THE I-35
CORRIDOR. THE ECMWF HAS BEEN THE MOST CONSISTENT IN FORECAST 850
MB WINDS THE PAST FEW DAYS...SO THIS FORECAST CLOSELY FOLLOWS THE
GUIDANCE OF THIS MODEL.
THE ECMWF MAINTAINS EASTERLY WINDS AT 850 MB THROUGH WEDNESDAY
MORNING. AS A RESULT...DROPPED POPS ON TUESDAY TO 10 PERCENT FOR
THE ENTIRE CWA WITH LESS CONFIDENCE IN MOISTURE AVAILABLE AND
INSTABILITY TUESDAY AFTERNOON. THE 850 MB FLOW VEERS THROUGHOUT
THE DAY ON WEDNESDAY SLOWLY SENDING RICH GULF MOISTURE NORTH INTO
THE CWA FROM THE SOUTHEAST WEDNESDAY AFTERNOON. WENT AHEAD WITH 20
PERCENT CHANCE OF STORMS FOR THE SOUTHEASTERN HALF OF THE FORECAST
AREA AS A RESULT. BY THURSDAY AFTERNOON...H850 FLOW IS SOUTH-
SOUTHEASTERLY WHICH WOULD START SENDING SOME DEEPER TROPICAL
MOISTURE INTO THE CWA. WENT AHEAD WITH WIDESPREAD 20 POPS FOR THE
ENTIRE AREA THURSDAY AND THURSDAY NIGHT ASSUMING THE ECMWF PANS
OUT AS EXPECTED. WHILE THE GFS HAS TIMING DIFFERENCES...ONCE THE
850 MB FLOW VEERS AROUND TO THE SOUTHEAST...THE GFS INDICATES
PWATS INCREASE TO 2 INCHES. THIS WOULD BE GETTING CLOSE TO 2
STANDARD DEVIATIONS ABOVE NORMAL FOR THIS TIME OF YEAR WHICH
CERTAINLY SUPPORTS THE BROAD BRUSHED POPS.
FRIDAY AND SATURDAY...THE BIG QUESTION FOR THIS PERIOD IS...WILL
WE HAVE MID AND UPPER LEVEL TROPICAL MOISTURE IN PLACE COURTESY OF
MANUEL AND INGRID? IF WE DO...POPS WILL HAVE TO BE INCREASED MORE
THAN WHAT WE ARE CARRYING AT THIS TIME. EACH DAY A DIFFERENT MODEL
SHOWS THIS SOLUTION WHILE ANOTHER ONE BACKS OFF. THE CONSENSUS IS
ALWAYS AN ANSWER OF /NO/...BUT THE CONSENSUS NEVER CONSISTS OF THE
SAME MODELS. AS A RESULT CONFIDENCE IS LOW AS TO WHERE THE MEXICAN
TROPICAL MOISTURE PLUME WILL END UP AT THIS TIME.
EITHER WAY...THE CONSENSUS OF MODEL GUIDANCE CONTINUES TO SHOW A
SEASONABLY STRONG TROUGH MOVING EAST OVER THE PLAINS DURING THIS
TIME FRAME. THIS WOULD SEND A STRONGER COLD FRONT SOUTH INTO NORTH
TX WHICH SUPPORTS AT LEAST SCATTERED THUNDERSTORMS AS IT MOVES
SOUTH THROUGH THE REGION. WE ALREADY HAD 30 TO 40 POPS IN THE
FORECAST ALONG THIS FRONT...SO JUST MAINTAINED THIS FORECAST AT
THIS TIME. WILL CONTINUE TO CLOSELY MONITOR THE MEXICAN TROPICAL
MOISTURE PLUME IN THE COMING DAYS. IF THIS MOISTURE IS IN PLACE IT
DOES NOT REALLY CHANGE WHEN WE EXPECT SHOWERS AND STORMS...IT JUST
AFFECTS THE COVERAGE AND AMOUNTS OF RAINFALL. EITHER WAY...WE WILL
LIKELY BE DRY ON SUNDAY AS SUBSIDENCE SWEEPS THROUGH THE REGION.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 95 76 95 77 96 / 30 20 10 10 10
WACO, TX 96 74 96 75 96 / 10 10 10 10 20
PARIS, TX 96 70 95 72 95 / 20 20 10 10 10
DENTON, TX 94 73 94 74 95 / 30 20 10 10 10
MCKINNEY, TX 95 73 95 75 96 / 30 20 10 10 10
DALLAS, TX 97 78 96 79 97 / 30 20 10 10 10
TERRELL, TX 96 75 96 75 97 / 20 20 10 10 10
CORSICANA, TX 97 75 97 76 97 / 10 10 10 10 20
TEMPLE, TX 96 73 95 72 95 / 10 10 10 10 20
MINERAL WELLS, TX 93 71 93 72 94 / 30 20 10 10 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
58/85
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1047 AM CDT MON SEP 16 2013
.UPDATE...
LOCAL 15Z SURFACE ANALYSIS SHOWS A COLD FRONT IN NORTHERN OKLAHOMA
WITH CONVECTION ONGOING IN CLOSE PROXIMITY TO THE FRONT. AN OUTFLOW
BOUNDARY HAS SURGED SOUTH OVERNIGHT AND THE BOUNDARY IS JUST
ENTERING OUR NORTHWESTERN ZONES. THE MOVEMENT HAS SLOWED DOWN AS
HEATING HAS COMMENCED...BUT DO EXPECT A CONTINUED MOVEMENT THIS
MORNING. THIS BOUNDARY WILL LIKELY SERVE AS A MECHANISM FOR
SHOWERS AND THUNDERSTORM DEVELOPMENT THIS AFTERNOON ACROSS THE
NORTHERN HALF OF THE FORECAST AREA. CURRENT POP CONFIGURATION
LOOKS GOOD AND WILL MAKE NO CHANGES AT THIS TIME. NOT EXPECTING
SEVERE WEATHER AS CAPE VALUES REMAIN LESS THAN 1500 J/KG AND
SURFACE DEWPOINTS IN THE UPPER 60S SHOULD PREVENT DOWNBURST WINDS.
HOWEVER...A STRONG STORM IS POSSIBLE WITH GUSTY WINDS UP TO 50
MPH.
HAMPSHIRE
&&
.AVIATION...
VFR CONDITIONS ARE EXPECTED THROUGH THIS FORECAST AT ALL
TERMINALS.
ALTHOUGH A BOUNDARY MOVING SOUTHEAST OUT OF SOUTHWESTERN OKLAHOMA
WILL REMAIN NORTHWEST OF THE METROPLEX TERMINALS THIS AFTERNOON
AND EVENING...ISOLATED TO WIDELY SCATTERED SHRA/TSRA WILL BE
POSSIBLE AROUND THE METROPLEX AND WILL CARRY VCTS FOR THE
METROPLEX TERMINALS 22-01Z. FEEL CONVECTION WILL REMAIN FAR
OUTSIDE OF KACT AERODROME TODAY AND THIS EVENING. LIGHT SOUTHEAST
WINDS THIS MORNING WILL BECOME MORE EASTERLY BY MIDDAY AND SHOULD
REMAIN SO AND LIGHT IN SPEED THROUGH TUESDAY MID- MORNING. 75
&&
.PREV DISCUSSION... /ISSUED 408 AM CDT MON SEP 16 2013/
EARLY MORNING WATER VAPOR SATELLITE IMAGERY SHOWED AN EXTENSIVE
PLUME OF TROPICAL MOISTURE OVER CENTRAL MEXICO DUE TO TROPICAL
DEPRESSION MANUEL MOVING ONSHORE THE WEST CENTRAL MEXICAN COAST. A
SECONDARY TROPICAL PLUME OF MOISTURE ASSOCIATED WITH HURRICANE
INGRID REMAINED JUST OFF SHORE OF THE NORTHEAST MEXICAN COAST.
ACROSS THE CONUS...A STRONG UPPER LEVEL TROUGH CONTINUED TO MOVE
SOUTHEAST OVER THE GREAT LAKES REGION TOWARDS THE EAST COAST. THE
SUBTROPICAL RIDGING THAT HAD BEEN DOMINATING THE PLAINS HAD BEEN
FLATTENED AND TILTED OVER THE SOUTHEASTERN UNITED STATES IN
RESPONSE TO THE PASSAGE OF THE STRONG NORTHERN STREAM TROUGH. THIS
LEFT GENERALLY WEAK WESTERLY FLOW OVER THE CENTRAL AND SOUTH
PLAINS THIS MORNING. A WEAK SHORTWAVE TROUGH WAS OBSERVED OVER THE
TX AND OK PANHANDLES...MOVING SLOWLY EAST ALONG A NEARLY STALLED
OUT COLD FRONT.
REGIONAL RADARS SHOWED A LARGE CLUSTER OF SHOWERS AND THUNDERSTORMS
ASSOCIATED WITH THE FRONT AND SHORTWAVE TROUGH AT 0830Z OR 330 AM
EXTENDING FROM AMARILLO TO NORTH CENTRAL OK. KFDR RADAR WAS
TRACKING A CONSOLIDATED OUTFLOW BOUNDARY THAT WAS MOVING SOUTHEAST
AWAY FROM THESE SHOWERS AND STORMS TOWARDS NORTH TEXAS.
TODAY...THE RAP AND THE NAM BOTH BOTH INDICATE THAT THE
CONSOLIDATED OUTFLOW BOUNDARY MOVING TOWARDS NORTH TEXAS EARLY
THIS MORNING WILL CONTINUE SOUTHEAST INTO THE CWA JUST AFTER
SUNRISE. THIS BOUNDARY WILL LIKELY STALL OUT SOMEWHERE NORTHWEST
OF THE DFW METROPLEX...WITH THE LATEST GUIDANCE SUGGESTING THE
BOUNDARY WILL COME TO REST NEAR A GAINESVILLE TO WEATHERFORD TO
CISCO LINE BY LATE THIS MORNING. LOCATIONS NEAR AND NORTHWEST OF
THE BOUNDARY WILL LIKELY SEE SOME ISOLATED TO SCATTERED RAIN
SHOWERS AND THUNDERSTORMS DEVELOP BY THE EARLY AFTERNOON HOURS OF
THE DAY. THIS IS PRIMARILY DUE TO THE FACT THAT THERE IS AMPLE
LOW-LEVEL MOISTURE IN PLACE TO SUPPORT PRECIPITATION...WITH THE
FRONT ACTING AS A LIFTING MECHANISM IN AN ENVIRONMENT
CHARACTERIZED WITH LITTLE TO NO CAPPING INVERSION ALOFT. WENT
AHEAD WITH A 30 PERCENT CHANCE OF RAIN FOR THESE LOCATIONS AS A
RESULT...INCLUDING MUCH OF THE DFW AREA.
ELSEWHERE ACROSS NORTH AND CENTRAL TEXAS...THE THERMODYNAMIC
ENVIRONMENT WILL BE NEARLY EQUIVALENT TO LOCATIONS NEAR THE
OUTFLOW BOUNDARY...BUT THERE IS NO OBVIOUS LIFTING MECHANISM TO
SUPPORT THE INITIATION OF SHOWERS AND STORMS THIS AFTERNOON.
DURING THE PEAK HEATING HOURS OF THE DAY...THE BUOYANCY FORCE WILL
BE MAXIMIZED...AND ISOLATED SHOWERS AND STORMS MAY DEVELOP
ANYWHERE ACROSS THE CWA AS A RESULT. MOST PRECIPITATION SHOULD
REMAIN TIED TO DAYTIME HEATING TODAY...THEREFORE WENT AHEAD AND
KEPT A MENTION OF SHOWERS AND STORMS IN THE FORECAST ONLY THROUGH
03Z THIS EVENING.
HEATING IS A BIT OF A CONCERN TODAY BECAUSE WE HAVE EXTENSIVE
CLOUD COVER IN THE FORM OF CIRRUS CLOUDS OVER THE REGION. THESE
CLOUDS MAY BREAK UP A BIT THROUGHOUT THE DAY...BUT WE WILL NEVER
BE FULLY RID OF THEM. REGARDLESS...AT 3 AM REGIONAL TEMPERATURES
WERE HOLDING IN THE MID TO UPPER 70S FOR MOST LOCATIONS. SO
DESPITE PERSISTENT CIRRUS CLOUDS TO CONTEND WITH...A 15 TO 20
DEGREE TEMPERATURE INCREASE SHOULD BE EASY TO ATTAIN BRINGING MOST
LOCATIONS UP INTO THE MID 90S FOR HIGHS WHICH IS WARM ENOUGH TO
SUPPORT ISOLATED STORMS IN THE FORECAST.
CONCERNING THE REMNANTS OF INGRID AND MANUEL...WITH THE
SUBTROPICAL RIDGE FLATTENED OUT...ITS CENTER OF CIRCULATION IS
EXPECTED TO SET UP ANYWHERE FROM SOUTHEAST TX TO THE MISSISSIPPI
COAST THROUGH THIS PERIOD. THE EXACT POSITION OF THIS RIDGE WILL
PLAY A LARGE ROLE IN TROPOSPHERIC STEERING FLOW/TRAJECTORIES FOR
TROPICAL MOISTURE INTO NORTH TX THROUGHOUT THE WEEK HEADED INTO
THIS WEEKEND. IF THE SUBTROPICAL RIDGE SETS UP FURTHER EAST...DEEP
TROPOSPHERIC FLOW WOULD FAVOR TRANSPORTING THE COMBINED MOISTURE
PLUMES FROM MANUEL AND INGRID FROM NORTHERN MEXICO INTO NORTH TX
BY LATE THIS WEEK. IF THE RIDGE SETS UP FURTHER WEST...THE MID AND
UPPER LEVEL TROPICAL MOISTURE WILL BE SHUNTED WEST AWAY FROM
TEXAS. UNFORTUNATELY MODELS REMAIN INCONSISTENT WITH REGARDS TO
THIS SOLUTION...SO DID NOT MAKE ANY HUGE ADJUSTMENTS TO THE
PREVIOUS FORECAST AT THIS TIME.
IN GENERAL...CONTINUE TO CARRY LOW POPS/RAIN CHANCES FROM TUESDAY
THROUGH THURSDAY...BECOMING MORE CONFIDENT AND WIDESPREAD WITH
RAIN CHANCES FOR FRIDAY AND SATURDAY BEFORE RETURNING TO A DRY
FORECAST ON SUNDAY. FOR MORE DETAILS READ ON...
TUESDAY THROUGH THURSDAY...REGARDLESS OF WHAT HAPPENS WITH THE
TROPICAL MOISTURE PLUME FROM THE MEXICAN TROPICAL CYCLONES...THE
MOST IMPORTANT THING TO WATCH DURING THIS TIME FRAME IS THE
DIRECTION OF LOW LEVEL WINDS. LOOKING AT THE 850 MB LEVEL...WINDS
THAT REMAIN EASTERLY NEAR THE GULF COAST WILL PREVENT RICH LOW-
LEVEL MOISTURE FROM MAKING ITS WAY NORTH INTO NORTH TX WHILE
SOUTHEASTERLY WINDS WILL SEND THIS MOISTURE RIGHT UP THE I-35
CORRIDOR. THE ECMWF HAS BEEN THE MOST CONSISTENT IN FORECAST 850
MB WINDS THE PAST FEW DAYS...SO THIS FORECAST CLOSELY FOLLOWS THE
GUIDANCE OF THIS MODEL.
THE ECMWF MAINTAINS EASTERLY WINDS AT 850 MB THROUGH WEDNESDAY
MORNING. AS A RESULT...DROPPED POPS ON TUESDAY TO 10 PERCENT FOR
THE ENTIRE CWA WITH LESS CONFIDENCE IN MOISTURE AVAILABLE AND
INSTABILITY TUESDAY AFTERNOON. THE 850 MB FLOW VEERS THROUGHOUT
THE DAY ON WEDNESDAY SLOWLY SENDING RICH GULF MOISTURE NORTH INTO
THE CWA FROM THE SOUTHEAST WEDNESDAY AFTERNOON. WENT AHEAD WITH 20
PERCENT CHANCE OF STORMS FOR THE SOUTHEASTERN HALF OF THE FORECAST
AREA AS A RESULT. BY THURSDAY AFTERNOON...H850 FLOW IS SOUTH-
SOUTHEASTERLY WHICH WOULD START SENDING SOME DEEPER TROPICAL
MOISTURE INTO THE CWA. WENT AHEAD WITH WIDESPREAD 20 POPS FOR THE
ENTIRE AREA THURSDAY AND THURSDAY NIGHT ASSUMING THE ECMWF PANS
OUT AS EXPECTED. WHILE THE GFS HAS TIMING DIFFERENCES...ONCE THE
850 MB FLOW VEERS AROUND TO THE SOUTHEAST...THE GFS INDICATES
PWATS INCREASE TO 2 INCHES. THIS WOULD BE GETTING CLOSE TO 2
STANDARD DEVIATIONS ABOVE NORMAL FOR THIS TIME OF YEAR WHICH
CERTAINLY SUPPORTS THE BROAD BRUSHED POPS.
FRIDAY AND SATURDAY...THE BIG QUESTION FOR THIS PERIOD IS...WILL
WE HAVE MID AND UPPER LEVEL TROPICAL MOISTURE IN PLACE COURTESY OF
MANUEL AND INGRID? IF WE DO...POPS WILL HAVE TO BE INCREASED MORE
THAN WHAT WE ARE CARRYING AT THIS TIME. EACH DAY A DIFFERENT MODEL
SHOWS THIS SOLUTION WHILE ANOTHER ONE BACKS OFF. THE CONSENSUS IS
ALWAYS AN ANSWER OF /NO/...BUT THE CONSENSUS NEVER CONSISTS OF THE
SAME MODELS. AS A RESULT CONFIDENCE IS LOW AS TO WHERE THE MEXICAN
TROPICAL MOISTURE PLUME WILL END UP AT THIS TIME.
EITHER WAY...THE CONSENSUS OF MODEL GUIDANCE CONTINUES TO SHOW A
SEASONABLY STRONG TROUGH MOVING EAST OVER THE PLAINS DURING THIS
TIME FRAME. THIS WOULD SEND A STRONGER COLD FRONT SOUTH INTO NORTH
TX WHICH SUPPORTS AT LEAST SCATTERED THUNDERSTORMS AS IT MOVES
SOUTH THROUGH THE REGION. WE ALREADY HAD 30 TO 40 POPS IN THE
FORECAST ALONG THIS FRONT...SO JUST MAINTAINED THIS FORECAST AT
THIS TIME. WILL CONTINUE TO CLOSELY MONITOR THE MEXICAN TROPICAL
MOISTURE PLUME IN THE COMING DAYS. IF THIS MOISTURE IS IN PLACE IT
DOES NOT REALLY CHANGE WHEN WE EXPECT SHOWERS AND STORMS...IT JUST
AFFECTS THE COVERAGE AND AMOUNTS OF RAINFALL. EITHER WAY...WE WILL
LIKELY BE DRY ON SUNDAY AS SUBSIDENCE SWEEPS THROUGH THE REGION.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 95 76 95 77 96 / 30 20 10 10 10
WACO, TX 96 74 96 75 96 / 10 10 10 10 20
PARIS, TX 96 70 95 72 95 / 20 20 10 10 10
DENTON, TX 94 73 94 74 95 / 30 20 10 10 10
MCKINNEY, TX 95 73 95 75 96 / 30 20 10 10 10
DALLAS, TX 97 78 96 79 97 / 30 20 10 10 10
TERRELL, TX 96 75 96 75 97 / 20 20 10 10 10
CORSICANA, TX 97 75 97 76 97 / 10 10 10 10 20
TEMPLE, TX 96 73 95 72 95 / 10 10 10 10 20
MINERAL WELLS, TX 93 71 93 72 94 / 30 20 10 10 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
623 AM CDT MON SEP 16 2013
.DISCUSSION...
SEE AVIATION FOR 12Z TAF ISSUANCE
&&
.AVIATION...
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. DEEPER MOISTURE
ALONG THE COAST WILL AID IN SCATTERED SHOWER DEVELOPMENT LATER
THIS MORNING INTO EARLY AFTERNOON. GREATEST COVERAGE WILL REMAIN
TO THE SOUTH AND WEST OF THE TERMINALS BUT CONFIDENCE IS HIGH
ENOUGH TO INCLUDE A VCSH FOR SGR...LBX...AND GLS. SOME MODEL
GUIDANCE EXPANDS THE SHRA ACTIVITY UP TO HOU BUT FEEL THAT THEY
WILL REMAIN RIGHT ON THE EDGE OF THE BETTER MOISTURE AND HAVE
LEFT OUT VCSH MENTION FOR NOW. 38
&&
.PREV DISCUSSION... /ISSUED 428 AM CDT MON SEP 16 2013/
DISCUSSION...
THE RADAR THIS MORNING SHOWS A FEW SHOWERS ALONG THE COAST MAINLY
BETWEEN KLBX AND KBYY. SFC ANALYSIS SHOWS DISSIPATING FRONT OVER E
TX THROUGH C LA. ANOTHER COLD FRONT WAS PUSHING THROUGH THE S
PLAINS BUT LIKELY STALL BEFORE EVEN REACHING TX. THERE IS A WEAK
COASTAL TROUGH DUE TO HURRICANE INGRID JUST OFF THE COAST OF
MEXICO. THIS HAS HELPED FORCE SOME SHOWERS BUT MOST OF THE
ACTIVITY IS OVER S TX. ANALYSIS OF 500MB SHOWS THAT THE UPPER
LEVEL RIDGE OVER TX HAS STRENGTHENED AND BROADENED THROUGH THE
GULF COAST INTO THE CAROLINAS. THIS HAS PROVIDED ENOUGH STEERING
TO PUSH INGRID TOWARDS MEXICO. THE 00Z CRP SOUNDING SHOWS NEARLY
2.1 INCHES OF PRECIP WATER AND GOES SOUNDER IMAGERY SHOWS THAT
THIS MUCH MOISTURE ALSO EXTENDS INTO SE TX. CERTAINLY EXPECT
THERE TO BE MORE CONVECTION ONCE DAY TIME HEATING OCCURS. LATEST
06Z HRRR RUN SHOWS CONVECTION FORMING ALONG THE COAST AND THEN
DEVELOPING INLAND BETWEEN HOUSTON AND VICTORIA ALONG US 59. THIS
MAY BE WHERE THE BEST MOISTURE EXISTS AND WHERE SUBSIDENCE FROM
THE UPPER LEVEL RIDGE MAY BE WEAKEST. THAT WILL BE THE MAIN
CHALLENGE THROUGH MID WEEK...FORECASTING CONVECTIVE COVERAGE DUE
TO DEEP MOISTURE AND WHETHER THE RIDGE WILL BE STRONG ENOUGH TO
INHIBIT CONVECTION. DECIDED TO KEEP 20/30 POPS IN THE FORECAST
THROUGH WED. MAX TEMPS WILL ALSO BE TRICKY DUE TO CLOUD COVER BUT
DECIDED TO HEDGE MAX TEMPS A DEGREE OR TWO ABOVE GUIDANCE AS STILL
ENOUGH DAY LIGHT FOR HEATING.
AFTER WEDNESDAY FORECAST MODELS SHOW THE UPPER LEVEL RIDGE
WEAKENING WITH A POTENT TROUGH PUSHING ACROSS THE N PLAINS. THUR
INTO FRI LOOKS LIKE DEEP BOUNDARY LAYER FLOW OFF THE GULF AND EVEN
FROM THE CARIBBEAN DEVELOPS. PRECIP WATER VALUES INCREASE TO 2-2.2
INCHES ON THUR AND MAX OUT AT 2.5 INCHES ON FRI PER THE GFS. BOTH
THE ECMWF AND GFS ARE RATHER WET FOR FRI INTO SAT. AS SUCH WILL
HAVE 30/40 POPS FOR THUR AND THEN 40 POPS FRI INTO SAT. THERE IS
THE POTENTIAL FOR HIGHER POPS AS THIS IS STILL DAY 5/6 OF THE
FORECAST. STILL PLENTY OF TIME FOR THE FORECAST TO CHANGE BUT
THERE IS A LEAST A COUPLE OF DAYS OF MODEL CONSISTENCY FOR THE 00Z
MODELS SHOWING THE POTENTIAL FOR RAINFALL FOR THE END OF THE WEEK.
MAX TEMPS FOR THE WEEK WILL BE IN LINE WITH GUIDANCE...MAYBE A
DEGREE OR TWO WARMER DUE TO THE RIDGE FOR THE NEXT COUPLE OF DAYS.
AS FOR HURRICANE INGRID...AGAIN SHOULD HAVE VERY LITTLE IMPACT
FOR SE TX AS IT SHOULD BE MAKING LANDFALL NORTH OF TAMPICO. THE
HURRICANE IS UNDER THE INFLUENCE OF SOME UPPER LEVEL SHEAR SO IT
IS ONLY A MINIMAL HURRICANE. MAIN IMPACTS FOR SE TX WILL JUST BE
CAUSING AN INFLUX OF MOISTURE AND MARINE INFLUENCES. RIP CURRENTS
WILL BE AN ISSUE AS WILL HIGHER SURF. ELEVATED TIDES OF A FOOT
ABOVE NORMAL LOOKS TO BE THE PEAK SO COASTAL FLOODING WILL NOT BE
A PROBLEM.
39
MARINE...
MODERATE TO STRONG EASTERLY FLOW WILL CONTINUE TODAY AS WE LIE IN
A TIGHT PRESSURE GRADIENT BETWEEN HIGH PRESSURE ACROSS THE
SOUTHEASTERN UNITED STATES AND HURRICANE INGRID ALONG THE MEXICAN
COAST. WITH SEAS AND WINDS EXPECTED TO REMAIN ELEVATED HAVE
EXTENDED THE SCA FOR ALL OFFSHORE WATERS AND CAUTION FOR BAYS
THROUGH TUESDAY MORNING. TIDE LEVELS WILL REMAIN BETWEEN ONE HALF
AND ONE FOOT ABOVE NORMAL. 38
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 95 75 95 74 96 / 10 10 20 10 20
HOUSTON (IAH) 93 75 94 74 94 / 20 10 20 10 20
GALVESTON (GLS) 90 81 89 80 89 / 20 20 20 20 30
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH TUESDAY MORNING FOR
THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY.
SMALL CRAFT ADVISORY UNTIL 8 AM CDT TUESDAY FOR THE FOLLOWING
ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
20 NM TO 60 NM...WATERS FROM FREEPORT TO THE MATAGORDA SHIP
CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20
TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM.
&&
$$
DISCUSSION...39
AVIATION/MARINE...38
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
613 AM CDT MON SEP 16 2013
.AVIATION...
VFR CONDITIONS ARE EXPECTED THROUGH THIS FORECAST AT ALL
TERMINALS.
ALTHOUGH A BOUNDARY MOVING SOUTHEAST OUT OF SOUTHWESTERN OKLAHOMA
WILL REMAIN NORTHWEST OF THE METROPLEX TERMINALS THIS AFTERNOON
AND EVENING...ISOLATED TO WIDELY SCATTERED SHRA/TSRA WILL BE
POSSIBLE AROUND THE METROPLEX AND WILL CARRY VCTS FOR THE
METROPLEX TERMINALS 22-01Z. FEEL CONVECTION WILL REMAIN FAR
OUTSIDE OF KACT AERODROME TODAY AND THIS EVENING. LIGHT SOUTHEAST
WINDS THIS MORNING WILL BECOME MORE EASTERLY BY MIDDAY AND SHOULD
REMAIN SO AND LIGHT IN SPEED THROUGH TUESDAY MID- MORNING. 75
&&
.PREV DISCUSSION... /ISSUED 408 AM CDT MON SEP 16 2013/
EARLY MORNING WATER VAPOR SATELLITE IMAGERY SHOWED AN EXTENSIVE
PLUME OF TROPICAL MOISTURE OVER CENTRAL MEXICO DUE TO TROPICAL
DEPRESSION MANUEL MOVING ONSHORE THE WEST CENTRAL MEXICAN COAST. A
SECONDARY TROPICAL PLUME OF MOISTURE ASSOCIATED WITH HURRICANE
INGRID REMAINED JUST OFF SHORE OF THE NORTHEAST MEXICAN COAST.
ACROSS THE CONUS...A STRONG UPPER LEVEL TROUGH CONTINUED TO MOVE
SOUTHEAST OVER THE GREAT LAKES REGION TOWARDS THE EAST COAST. THE
SUBTROPICAL RIDGING THAT HAD BEEN DOMINATING THE PLAINS HAD BEEN
FLATTENED AND TILTED OVER THE SOUTHEASTERN UNITED STATES IN
RESPONSE TO THE PASSAGE OF THE STRONG NORTHERN STREAM TROUGH. THIS
LEFT GENERALLY WEAK WESTERLY FLOW OVER THE CENTRAL AND SOUTH
PLAINS THIS MORNING. A WEAK SHORTWAVE TROUGH WAS OBSERVED OVER THE
TX AND OK PANHANDLES...MOVING SLOWLY EAST ALONG A NEARLY STALLED
OUT COLD FRONT.
REGIONAL RADARS SHOWED A LARGE CLUSTER OF SHOWERS AND THUNDERSTORMS
ASSOCIATED WITH THE FRONT AND SHORTWAVE TROUGH AT 0830Z OR 330 AM
EXTENDING FROM AMARILLO TO NORTH CENTRAL OK. KFDR RADAR WAS
TRACKING A CONSOLIDATED OUTFLOW BOUNDARY THAT WAS MOVING SOUTHEAST
AWAY FROM THESE SHOWERS AND STORMS TOWARDS NORTH TEXAS.
TODAY...THE RAP AND THE NAM BOTH BOTH INDICATE THAT THE
CONSOLIDATED OUTFLOW BOUNDARY MOVING TOWARDS NORTH TEXAS EARLY
THIS MORNING WILL CONTINUE SOUTHEAST INTO THE CWA JUST AFTER
SUNRISE. THIS BOUNDARY WILL LIKELY STALL OUT SOMEWHERE NORTHWEST
OF THE DFW METROPLEX...WITH THE LATEST GUIDANCE SUGGESTING THE
BOUNDARY WILL COME TO REST NEAR A GAINESVILLE TO WEATHERFORD TO
CISCO LINE BY LATE THIS MORNING. LOCATIONS NEAR AND NORTHWEST OF
THE BOUNDARY WILL LIKELY SEE SOME ISOLATED TO SCATTERED RAIN
SHOWERS AND THUNDERSTORMS DEVELOP BY THE EARLY AFTERNOON HOURS OF
THE DAY. THIS IS PRIMARILY DUE TO THE FACT THAT THERE IS AMPLE
LOW-LEVEL MOISTURE IN PLACE TO SUPPORT PRECIPITATION...WITH THE
FRONT ACTING AS A LIFTING MECHANISM IN AN ENVIRONMENT
CHARACTERIZED WITH LITTLE TO NO CAPPING INVERSION ALOFT. WENT
AHEAD WITH A 30 PERCENT CHANCE OF RAIN FOR THESE LOCATIONS AS A
RESULT...INCLUDING MUCH OF THE DFW AREA.
ELSEWHERE ACROSS NORTH AND CENTRAL TEXAS...THE THERMODYNAMIC
ENVIRONMENT WILL BE NEARLY EQUIVALENT TO LOCATIONS NEAR THE
OUTFLOW BOUNDARY...BUT THERE IS NO OBVIOUS LIFTING MECHANISM TO
SUPPORT THE INITIATION OF SHOWERS AND STORMS THIS AFTERNOON.
DURING THE PEAK HEATING HOURS OF THE DAY...THE BUOYANCY FORCE WILL
BE MAXIMIZED...AND ISOLATED SHOWERS AND STORMS MAY DEVELOP
ANYWHERE ACROSS THE CWA AS A RESULT. MOST PRECIPITATION SHOULD
REMAIN TIED TO DAYTIME HEATING TODAY...THEREFORE WENT AHEAD AND
KEPT A MENTION OF SHOWERS AND STORMS IN THE FORECAST ONLY THROUGH
03Z THIS EVENING.
HEATING IS A BIT OF A CONCERN TODAY BECAUSE WE HAVE EXTENSIVE
CLOUD COVER IN THE FORM OF CIRRUS CLOUDS OVER THE REGION. THESE
CLOUDS MAY BREAK UP A BIT THROUGHOUT THE DAY...BUT WE WILL NEVER
BE FULLY RID OF THEM. REGARDLESS...AT 3 AM REGIONAL TEMPERATURES
WERE HOLDING IN THE MID TO UPPER 70S FOR MOST LOCATIONS. SO
DESPITE PERSISTENT CIRRUS CLOUDS TO CONTEND WITH...A 15 TO 20
DEGREE TEMPERATURE INCREASE SHOULD BE EASY TO ATTAIN BRINGING MOST
LOCATIONS UP INTO THE MID 90S FOR HIGHS WHICH IS WARM ENOUGH TO
SUPPORT ISOLATED STORMS IN THE FORECAST.
CONCERNING THE REMNANTS OF INGRID AND MANUEL...WITH THE
SUBTROPICAL RIDGE FLATTENED OUT...ITS CENTER OF CIRCULATION IS
EXPECTED TO SET UP ANYWHERE FROM SOUTHEAST TX TO THE MISSISSIPPI
COAST THROUGH THIS PERIOD. THE EXACT POSITION OF THIS RIDGE WILL
PLAY A LARGE ROLE IN TROPOSPHERIC STEERING FLOW/TRAJECTORIES FOR
TROPICAL MOISTURE INTO NORTH TX THROUGHOUT THE WEEK HEADED INTO
THIS WEEKEND. IF THE SUBTROPICAL RIDGE SETS UP FURTHER EAST...DEEP
TROPOSPHERIC FLOW WOULD FAVOR TRANSPORTING THE COMBINED MOISTURE
PLUMES FROM MANUEL AND INGRID FROM NORTHERN MEXICO INTO NORTH TX
BY LATE THIS WEEK. IF THE RIDGE SETS UP FURTHER WEST...THE MID AND
UPPER LEVEL TROPICAL MOISTURE WILL BE SHUNTED WEST AWAY FROM
TEXAS. UNFORTUNATELY MODELS REMAIN INCONSISTENT WITH REGARDS TO
THIS SOLUTION...SO DID NOT MAKE ANY HUGE ADJUSTMENTS TO THE
PREVIOUS FORECAST AT THIS TIME.
IN GENERAL...CONTINUE TO CARRY LOW POPS/RAIN CHANCES FROM TUESDAY
THROUGH THURSDAY...BECOMING MORE CONFIDENT AND WIDESPREAD WITH
RAIN CHANCES FOR FRIDAY AND SATURDAY BEFORE RETURNING TO A DRY
FORECAST ON SUNDAY. FOR MORE DETAILS READ ON...
TUESDAY THROUGH THURSDAY...REGARDLESS OF WHAT HAPPENS WITH THE
TROPICAL MOISTURE PLUME FROM THE MEXICAN TROPICAL CYCLONES...THE
MOST IMPORTANT THING TO WATCH DURING THIS TIME FRAME IS THE
DIRECTION OF LOW LEVEL WINDS. LOOKING AT THE 850 MB LEVEL...WINDS
THAT REMAIN EASTERLY NEAR THE GULF COAST WILL PREVENT RICH LOW-
LEVEL MOISTURE FROM MAKING ITS WAY NORTH INTO NORTH TX WHILE
SOUTHEASTERLY WINDS WILL SEND THIS MOISTURE RIGHT UP THE I-35
CORRIDOR. THE ECMWF HAS BEEN THE MOST CONSISTENT IN FORECAST 850
MB WINDS THE PAST FEW DAYS...SO THIS FORECAST CLOSELY FOLLOWS THE
GUIDANCE OF THIS MODEL.
THE ECMWF MAINTAINS EASTERLY WINDS AT 850 MB THROUGH WEDNESDAY
MORNING. AS A RESULT...DROPPED POPS ON TUESDAY TO 10 PERCENT FOR
THE ENTIRE CWA WITH LESS CONFIDENCE IN MOISTURE AVAILABLE AND
INSTABILITY TUESDAY AFTERNOON. THE 850 MB FLOW VEERS THROUGHOUT
THE DAY ON WEDNESDAY SLOWLY SENDING RICH GULF MOISTURE NORTH INTO
THE CWA FROM THE SOUTHEAST WEDNESDAY AFTERNOON. WENT AHEAD WITH 20
PERCENT CHANCE OF STORMS FOR THE SOUTHEASTERN HALF OF THE FORECAST
AREA AS A RESULT. BY THURSDAY AFTERNOON...H850 FLOW IS SOUTH-
SOUTHEASTERLY WHICH WOULD START SENDING SOME DEEPER TROPICAL
MOISTURE INTO THE CWA. WENT AHEAD WITH WIDESPREAD 20 POPS FOR THE
ENTIRE AREA THURSDAY AND THURSDAY NIGHT ASSUMING THE ECMWF PANS
OUT AS EXPECTED. WHILE THE GFS HAS TIMING DIFFERENCES...ONCE THE
850 MB FLOW VEERS AROUND TO THE SOUTHEAST...THE GFS INDICATES
PWATS INCREASE TO 2 INCHES. THIS WOULD BE GETTING CLOSE TO 2
STANDARD DEVIATIONS ABOVE NORMAL FOR THIS TIME OF YEAR WHICH
CERTAINLY SUPPORTS THE BROAD BRUSHED POPS.
FRIDAY AND SATURDAY...THE BIG QUESTION FOR THIS PERIOD IS...WILL
WE HAVE MID AND UPPER LEVEL TROPICAL MOISTURE IN PLACE COURTESY OF
MANUEL AND INGRID? IF WE DO...POPS WILL HAVE TO BE INCREASED MORE
THAN WHAT WE ARE CARRYING AT THIS TIME. EACH DAY A DIFFERENT MODEL
SHOWS THIS SOLUTION WHILE ANOTHER ONE BACKS OFF. THE CONSENSUS IS
ALWAYS AN ANSWER OF /NO/...BUT THE CONSENSUS NEVER CONSISTS OF THE
SAME MODELS. AS A RESULT CONFIDENCE IS LOW AS TO WHERE THE MEXICAN
TROPICAL MOISTURE PLUME WILL END UP AT THIS TIME.
EITHER WAY...THE CONSENSUS OF MODEL GUIDANCE CONTINUES TO SHOW A
SEASONABLY STRONG TROUGH MOVING EAST OVER THE PLAINS DURING THIS
TIME FRAME. THIS WOULD SEND A STRONGER COLD FRONT SOUTH INTO NORTH
TX WHICH SUPPORTS AT LEAST SCATTERED THUNDERSTORMS AS IT MOVES
SOUTH THROUGH THE REGION. WE ALREADY HAD 30 TO 40 POPS IN THE
FORECAST ALONG THIS FRONT...SO JUST MAINTAINED THIS FORECAST AT
THIS TIME. WILL CONTINUE TO CLOSELY MONITOR THE MEXICAN TROPICAL
MOISTURE PLUME IN THE COMING DAYS. IF THIS MOISTURE IS IN PLACE IT
DOES NOT REALLY CHANGE WHEN WE EXPECT SHOWERS AND STORMS...IT JUST
AFFECTS THE COVERAGE AND AMOUNTS OF RAINFALL. EITHER WAY...WE WILL
LIKELY BE DRY ON SUNDAY AS SUBSIDENCE SWEEPS THROUGH THE REGION.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 95 76 95 77 96 / 30 20 10 10 10
WACO, TX 96 74 96 75 96 / 10 10 10 10 20
PARIS, TX 96 70 95 72 95 / 20 20 10 10 10
DENTON, TX 94 73 94 74 95 / 30 20 10 10 10
MCKINNEY, TX 95 73 95 75 96 / 30 20 10 10 10
DALLAS, TX 97 78 96 79 97 / 30 20 10 10 10
TERRELL, TX 96 75 96 75 97 / 20 20 10 10 10
CORSICANA, TX 97 75 97 76 97 / 10 10 10 10 20
TEMPLE, TX 96 73 95 72 95 / 10 10 10 10 20
MINERAL WELLS, TX 92 71 93 72 94 / 30 20 10 10 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
75/
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
428 AM CDT MON SEP 16 2013
.DISCUSSION...
THE RADAR THIS MORNING SHOWS A FEW SHOWERS ALONG THE COAST MAINLY
BETWEEN KLBX AND KBYY. SFC ANALYSIS SHOWS DISSIPATING FRONT OVER E
TX THROUGH C LA. ANOTHER COLD FRONT WAS PUSHING THROUGH THE S
PLAINS BUT LIKELY STALL BEFORE EVEN REACHING TX. THERE IS A WEAK
COASTAL TROUGH DUE TO HURRICANE INGRID JUST OFF THE COAST OF
MEXICO. THIS HAS HELPED FORCE SOME SHOWERS BUT MOST OF THE
ACTIVITY IS OVER S TX. ANALYSIS OF 500MB SHOWS THAT THE UPPER
LEVEL RIDGE OVER TX HAS STRENGTHENED AND BROADENED THROUGH THE
GULF COAST INTO THE CAROLINAS. THIS HAS PROVIDED ENOUGH STEERING
TO PUSH INGRID TOWARDS MEXICO. THE 00Z CRP SOUNDING SHOWS NEARLY
2.1 INCHES OF PRECIP WATER AND GOES SOUNDER IMAGERY SHOWS THAT
THIS MUCH MOISTURE ALSO EXTENDS INTO SE TX. CERTAINLY EXPECT
THERE TO BE MORE CONVECTION ONCE DAY TIME HEATING OCCURS. LATEST
06Z HRRR RUN SHOWS CONVECTION FORMING ALONG THE COAST AND THEN
DEVELOPING INLAND BETWEEN HOUSTON AND VICTORIA ALONG US 59. THIS
MAY BE WHERE THE BEST MOISTURE EXISTS AND WHERE SUBSIDENCE FROM
THE UPPER LEVEL RIDGE MAY BE WEAKEST. THAT WILL BE THE MAIN
CHALLENGE THROUGH MID WEEK...FORECASTING CONVECTIVE COVERAGE DUE
TO DEEP MOISTURE AND WHETHER THE RIDGE WILL BE STRONG ENOUGH TO
INHIBIT CONVECTION. DECIDED TO KEEP 20/30 POPS IN THE FORECAST
THROUGH WED. MAX TEMPS WILL ALSO BE TRICKY DUE TO CLOUD COVER BUT
DECIDED TO HEDGE MAX TEMPS A DEGREE OR TWO ABOVE GUIDANCE AS STILL
ENOUGH DAY LIGHT FOR HEATING.
AFTER WEDNESDAY FORECAST MODELS SHOW THE UPPER LEVEL RIDGE
WEAKENING WITH A POTENT TROUGH PUSHING ACROSS THE N PLAINS. THUR
INTO FRI LOOKS LIKE DEEP BOUNDARY LAYER FLOW OFF THE GULF AND EVEN
FROM THE CARIBBEAN DEVELOPS. PRECIP WATER VALUES INCREASE TO 2-2.2
INCHES ON THUR AND MAX OUT AT 2.5 INCHES ON FRI PER THE GFS. BOTH
THE ECMWF AND GFS ARE RATHER WET FOR FRI INTO SAT. AS SUCH WILL
HAVE 30/40 POPS FOR THUR AND THEN 40 POPS FRI INTO SAT. THERE IS
THE POTENTIAL FOR HIGHER POPS AS THIS IS STILL DAY 5/6 OF THE
FORECAST. STILL PLENTY OF TIME FOR THE FORECAST TO CHANGE BUT
THERE IS A LEAST A COUPLE OF DAYS OF MODEL CONSISTENCY FOR THE 00Z
MODELS SHOWING THE POTENTIAL FOR RAINFALL FOR THE END OF THE WEEK.
MAX TEMPS FOR THE WEEK WILL BE IN LINE WITH GUIDANCE...MAYBE A
DEGREE OR TWO WARMER DUE TO THE RIDGE FOR THE NEXT COUPLE OF DAYS.
AS FOR HURRICANE INGRID...AGAIN SHOULD HAVE VERY LITTLE IMPACT
FOR SE TX AS IT SHOULD BE MAKING LANDFALL NORTH OF TAMPICO. THE
HURRICANE IS UNDER THE INFLUENCE OF SOME UPPER LEVEL SHEAR SO IT
IS ONLY A MINIMAL HURRICANE. MAIN IMPACTS FOR SE TX WILL JUST BE
CAUSING AN INFLUX OF MOISTURE AND MARINE INFLUENCES. RIP CURRENTS
WILL BE AN ISSUE AS WILL HIGHER SURF. ELEVATED TIDES OF A FOOT
ABOVE NORMAL LOOKS TO BE THE PEAK SO COASTAL FLOODING WILL NOT BE
A PROBLEM.
39
&&
.MARINE...
MODERATE TO STRONG EASTERLY FLOW WILL CONTINUE TODAY AS WE LIE IN
A TIGHT PRESSURE GRADIENT BETWEEN HIGH PRESSURE ACROSS THE
SOUTHEASTERN UNITED STATES AND HURRICANE INGRID ALONG THE MEXICAN
COAST. WITH SEAS AND WINDS EXPECTED TO REMAIN ELEVATED HAVE
EXTENDED THE SCA FOR ALL OFFSHORE WATERS AND CAUTION FOR BAYS
THROUGH TUESDAY MORNING. TIDE LEVELS WILL REMAIN BETWEEN ONE HALF
AND ONE FOOT ABOVE NORMAL. 38
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 95 75 95 74 96 / 10 10 20 10 20
HOUSTON (IAH) 93 75 94 74 94 / 20 10 20 10 20
GALVESTON (GLS) 90 81 89 80 89 / 20 20 20 20 30
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH TUESDAY MORNING FOR
THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY.
SMALL CRAFT ADVISORY UNTIL 8 AM CDT TUESDAY FOR THE FOLLOWING
ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
20 NM TO 60 NM...WATERS FROM FREEPORT TO THE MATAGORDA SHIP
CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20
TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM.
&&
$$
DISCUSSION...39
AVIATION/MARINE...38
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
408 AM CDT MON SEP 16 2013
.DISCUSSION...
EARLY MORNING WATER VAPOR SATELLITE IMAGERY SHOWED AN EXTENSIVE
PLUME OF TROPICAL MOISTURE OVER CENTRAL MEXICO DUE TO TROPICAL
DEPRESSION MANUEL MOVING ONSHORE THE WEST CENTRAL MEXICAN COAST. A
SECONDARY TROPICAL PLUME OF MOISTURE ASSOCIATED WITH HURRICANE
INGRID REMAINED JUST OFF SHORE OF THE NORTHEAST MEXICAN COAST.
ACROSS THE CONUS...A STRONG UPPER LEVEL TROUGH CONTINUED TO MOVE
SOUTHEAST OVER THE GREAT LAKES REGION TOWARDS THE EAST COAST. THE
SUBTROPICAL RIDGING THAT HAD BEEN DOMINATING THE PLAINS HAD BEEN
FLATTENED AND TILTED OVER THE SOUTHEASTERN UNITED STATES IN
RESPONSE TO THE PASSAGE OF THE STRONG NORTHERN STREAM TROUGH. THIS
LEFT GENERALLY WEAK WESTERLY FLOW OVER THE CENTRAL AND SOUTH
PLAINS THIS MORNING. A WEAK SHORTWAVE TROUGH WAS OBSERVED OVER THE
TX AND OK PANHANDLES...MOVING SLOWLY EAST ALONG A NEARLY STALLED
OUT COLD FRONT.
REGIONAL RADARS SHOWED A LARGE CLUSTER OF SHOWERS AND THUNDERSTORMS
ASSOCIATED WITH THE FRONT AND SHORTWAVE TROUGH AT 0830Z OR 330 AM
EXTENDING FROM AMARILLO TO NORTH CENTRAL OK. KFDR RADAR WAS
TRACKING A CONSOLIDATED OUTFLOW BOUNDARY THAT WAS MOVING SOUTHEAST
AWAY FROM THESE SHOWERS AND STORMS TOWARDS NORTH TEXAS.
TODAY...THE RAP AND THE NAM BOTH BOTH INDICATE THAT THE
CONSOLIDATED OUTFLOW BOUNDARY MOVING TOWARDS NORTH TEXAS EARLY
THIS MORNING WILL CONTINUE SOUTHEAST INTO THE CWA JUST AFTER
SUNRISE. THIS BOUNDARY WILL LIKELY STALL OUT SOMEWHERE NORTHWEST
OF THE DFW METROPLEX...WITH THE LATEST GUIDANCE SUGGESTING THE
BOUNDARY WILL COME TO REST NEAR A GAINESVILLE TO WEATHERFORD TO
CISCO LINE BY LATE THIS MORNING. LOCATIONS NEAR AND NORTHWEST OF
THE BOUNDARY WILL LIKELY SEE SOME ISOLATED TO SCATTERED RAIN
SHOWERS AND THUNDERSTORMS DEVELOP BY THE EARLY AFTERNOON HOURS OF
THE DAY. THIS IS PRIMARILY DUE TO THE FACT THAT THERE IS AMPLE
LOW-LEVEL MOISTURE IN PLACE TO SUPPORT PRECIPITATION...WITH THE
FRONT ACTING AS A LIFTING MECHANISM IN AN ENVIRONMENT
CHARACTERIZED WITH LITTLE TO NO CAPPING INVERSION ALOFT. WENT
AHEAD WITH A 30 PERCENT CHANCE OF RAIN FOR THESE LOCATIONS AS A
RESULT...INCLUDING MUCH OF THE DFW AREA.
ELSEWHERE ACROSS NORTH AND CENTRAL TEXAS...THE THERMODYNAMIC
ENVIRONMENT WILL BE NEARLY EQUIVALENT TO LOCATIONS NEAR THE
OUTFLOW BOUNDARY...BUT THERE IS NO OBVIOUS LIFTING MECHANISM TO
SUPPORT THE INITIATION OF SHOWERS AND STORMS THIS AFTERNOON.
DURING THE PEAK HEATING HOURS OF THE DAY...THE BUOYANCY FORCE WILL
BE MAXIMIZED...AND ISOLATED SHOWERS AND STORMS MAY DEVELOP
ANYWHERE ACROSS THE CWA AS A RESULT. MOST PRECIPITATION SHOULD
REMAIN TIED TO DAYTIME HEATING TODAY...THEREFORE WENT AHEAD AND
KEPT A MENTION OF SHOWERS AND STORMS IN THE FORECAST ONLY THROUGH
03Z THIS EVENING.
HEATING IS A BIT OF A CONCERN TODAY BECAUSE WE HAVE EXTENSIVE
CLOUD COVER IN THE FORM OF CIRRUS CLOUDS OVER THE REGION. THESE
CLOUDS MAY BREAK UP A BIT THROUGHOUT THE DAY...BUT WE WILL NEVER
BE FULLY RID OF THEM. REGARDLESS...AT 3 AM REGIONAL TEMPERATURES
WERE HOLDING IN THE MID TO UPPER 70S FOR MOST LOCATIONS. SO
DESPITE PERSISTENT CIRRUS CLOUDS TO CONTEND WITH...A 15 TO 20
DEGREE TEMPERATURE INCREASE SHOULD BE EASY TO ATTAIN BRINGING MOST
LOCATIONS UP INTO THE MID 90S FOR HIGHS WHICH IS WARM ENOUGH TO
SUPPORT ISOLATED STORMS IN THE FORECAST.
CONCERNING THE REMNANTS OF INGRID AND MANUEL...WITH THE
SUBTROPICAL RIDGE FLATTENED OUT...ITS CENTER OF CIRCULATION IS
EXPECTED TO SET UP ANYWHERE FROM SOUTHEAST TX TO THE MISSISSIPPI
COAST THROUGH THIS PERIOD. THE EXACT POSITION OF THIS RIDGE WILL
PLAY A LARGE ROLE IN TROPOSPHERIC STEERING FLOW/TRAJECTORIES FOR
TROPICAL MOISTURE INTO NORTH TX THROUGHOUT THE WEEK HEADED INTO
THIS WEEKEND. IF THE SUBTROPICAL RIDGE SETS UP FURTHER EAST...DEEP
TROPOSPHERIC FLOW WOULD FAVOR TRANSPORTING THE COMBINED MOISTURE
PLUMES FROM MANUEL AND INGRID FROM NORTHERN MEXICO INTO NORTH TX
BY LATE THIS WEEK. IF THE RIDGE SETS UP FURTHER WEST...THE MID AND
UPPER LEVEL TROPICAL MOISTURE WILL BE SHUNTED WEST AWAY FROM
TEXAS. UNFORTUNATELY MODELS REMAIN INCONSISTENT WITH REGARDS TO
THIS SOLUTION...SO DID NOT MAKE ANY HUGE ADJUSTMENTS TO THE
PREVIOUS FORECAST AT THIS TIME.
IN GENERAL...CONTINUE TO CARRY LOW POPS/RAIN CHANCES FROM TUESDAY
THROUGH THURSDAY...BECOMING MORE CONFIDENT AND WIDESPREAD WITH
RAIN CHANCES FOR FRIDAY AND SATURDAY BEFORE RETURNING TO A DRY
FORECAST ON SUNDAY. FOR MORE DETAILS READ ON...
TUESDAY THROUGH THURSDAY...REGARDLESS OF WHAT HAPPENS WITH THE
TROPICAL MOISTURE PLUME FROM THE MEXICAN TROPICAL CYCLONES...THE
MOST IMPORTANT THING TO WATCH DURING THIS TIME FRAME IS THE
DIRECTION OF LOW LEVEL WINDS. LOOKING AT THE 850 MB LEVEL...WINDS
THAT REMAIN EASTERLY NEAR THE GULF COAST WILL PREVENT RICH LOW-
LEVEL MOISTURE FROM MAKING ITS WAY NORTH INTO NORTH TX WHILE
SOUTHEASTERLY WINDS WILL SEND THIS MOISTURE RIGHT UP THE I-35
CORRIDOR. THE ECMWF HAS BEEN THE MOST CONSISTENT IN FORECAST 850
MB WINDS THE PAST FEW DAYS...SO THIS FORECAST CLOSELY FOLLOWS THE
GUIDANCE OF THIS MODEL.
THE ECMWF MAINTAINS EASTERLY WINDS AT 850 MB THROUGH WEDNESDAY
MORNING. AS A RESULT...DROPPED POPS ON TUESDAY TO 10 PERCENT FOR
THE ENTIRE CWA WITH LESS CONFIDENCE IN MOISTURE AVAILABLE AND
INSTABILITY TUESDAY AFTERNOON. THE 850 MB FLOW VEERS THROUGHOUT
THE DAY ON WEDNESDAY SLOWLY SENDING RICH GULF MOISTURE NORTH INTO
THE CWA FROM THE SOUTHEAST WEDNESDAY AFTERNOON. WENT AHEAD WITH 20
PERCENT CHANCE OF STORMS FOR THE SOUTHEASTERN HALF OF THE FORECAST
AREA AS A RESULT. BY THURSDAY AFTERNOON...H850 FLOW IS SOUTH-
SOUTHEASTERLY WHICH WOULD START SENDING SOME DEEPER TROPICAL
MOISTURE INTO THE CWA. WENT AHEAD WITH WIDESPREAD 20 POPS FOR THE
ENTIRE AREA THURSDAY AND THURSDAY NIGHT ASSUMING THE ECMWF PANS
OUT AS EXPECTED. WHILE THE GFS HAS TIMING DIFFERENCES...ONCE THE
850 MB FLOW VEERS AROUND TO THE SOUTHEAST...THE GFS INDICATES
PWATS INCREASE TO 2 INCHES. THIS WOULD BE GETTING CLOSE TO 2
STANDARD DEVIATIONS ABOVE NORMAL FOR THIS TIME OF YEAR WHICH
CERTAINLY SUPPORTS THE BROAD BRUSHED POPS.
FRIDAY AND SATURDAY...THE BIG QUESTION FOR THIS PERIOD IS...WILL
WE HAVE MID AND UPPER LEVEL TROPICAL MOISTURE IN PLACE COURTESY OF
MANUEL AND INGRID? IF WE DO...POPS WILL HAVE TO BE INCREASED MORE
THAN WHAT WE ARE CARRYING AT THIS TIME. EACH DAY A DIFFERENT MODEL
SHOWS THIS SOLUTION WHILE ANOTHER ONE BACKS OFF. THE CONSENSUS IS
ALWAYS AN ANSWER OF /NO/...BUT THE CONSENSUS NEVER CONSISTS OF THE
SAME MODELS. AS A RESULT CONFIDENCE IS LOW AS TO WHERE THE MEXICAN
TROPICAL MOISTURE PLUME WILL END UP AT THIS TIME.
EITHER WAY...THE CONSENSUS OF MODEL GUIDANCE CONTINUES TO SHOW A
SEASONABLY STRONG TROUGH MOVING EAST OVER THE PLAINS DURING THIS
TIME FRAME. THIS WOULD SEND A STRONGER COLD FRONT SOUTH INTO NORTH
TX WHICH SUPPORTS AT LEAST SCATTERED THUNDERSTORMS AS IT MOVES
SOUTH THROUGH THE REGION. WE ALREADY HAD 30 TO 40 POPS IN THE
FORECAST ALONG THIS FRONT...SO JUST MAINTAINED THIS FORECAST AT
THIS TIME. WILL CONTINUE TO CLOSELY MONITOR THE MEXICAN TROPICAL
MOISTURE PLUME IN THE COMING DAYS. IF THIS MOISTURE IS IN PLACE IT
DOES NOT REALLY CHANGE WHEN WE EXPECT SHOWERS AND STORMS...IT JUST
AFFECTS THE COVERAGE AND AMOUNTS OF RAINFALL. EITHER WAY...WE WILL
LIKELY BE DRY ON SUNDAY AS SUBSIDENCE SWEEPS THROUGH THE REGION.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 95 76 95 77 96 / 30 20 10 10 10
WACO, TX 96 74 96 75 96 / 10 10 10 10 20
PARIS, TX 96 70 95 72 95 / 20 20 10 10 10
DENTON, TX 94 73 94 74 95 / 30 20 10 10 10
MCKINNEY, TX 95 73 95 75 96 / 30 20 10 10 10
DALLAS, TX 97 78 96 79 97 / 30 20 10 10 10
TERRELL, TX 96 75 96 75 97 / 20 20 10 10 10
CORSICANA, TX 97 75 97 76 97 / 10 10 10 10 20
TEMPLE, TX 96 73 95 72 95 / 10 10 10 10 20
MINERAL WELLS, TX 92 71 93 72 94 / 30 20 10 10 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)
AREA FORECAST DISCUSSION...UPDATED
NWS SPOKANE WA
725 PM PDT Tue Sep 17 2013
.SYNOPSIS...
A vigorous upper level disturbance will bring showers and
thunderstorms to north Idaho and the eastern third of Washington
tonight. Rain amounts of a half inch to an inch will be possible
over the Palouse into the Sliver Valley. Rain showers will linger
over the Idaho Panhandle on Wednesday. A drying and warming trend
will occur on Thursday and Friday. A slow moving cold front will
bring increasing chances for rain and cooler weather for the
weekend.
&&
.DISCUSSION...
Two areas of concern this evening. First area stretched from the
southeast corner of WA northeast towards Sandpoint. This area of
rain is mainly stratiform with an occiasonal lightning strike here
or there. Rainfall amounts have ranged from 0.15 to 0.30 with a
localized 0.50 at Corral Creek near the ID/WA/OR border. This band
of rain will keep pushing northeast through the night. The second
area of concern is across northern WA...mainly the Okanogan Valley
and Okanogan Highlands and northeast corner of WA. This has been a
bit more convective in nature. The storms are very slow moving and
radar has indicated rainfall amounts of an inch or more at several
locations. Have issued an Areal Flood Adisory for an area of
heavier rain from Nespelem to Keller to Miles. The precipitation is
very slow moving and the heavy rain could lead to localized
flooding on small creeks and streams as well as along
roadways...like Highway 21. The HRRR models shows this area of
showers slowly shifting east through the night and into Wednesday
morning across northeast WA and north ID. /Nisbet
&&
.AVIATION...
00Z TAFS: Rain and thunderstorms are underway over eastern
Washington and north Idaho. As anticipated the most widespread
activity is emerging from northeast Oregon and spreading into the
Idaho Panhandle. The 18z runs of the GFS and NAM are a bit more
progressive with the mid-level low on Wednesday morning. The 00z
TAFs are a bit more optimistic with ceilings given the trend for not
as much rain, but this is not a particularly high confidence
forecast. It is possible that the 12z runs were more correct and low
stratus may be locked into Spokane and Coeur D`Alene through mid
day. /GKoch
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 50 62 46 75 50 79 / 100 50 10 0 0 0
Coeur d`Alene 49 60 44 73 48 78 / 100 80 10 0 0 0
Pullman 48 63 41 77 46 81 / 100 30 10 0 0 0
Lewiston 53 68 49 83 53 87 / 100 20 10 0 0 0
Colville 50 65 43 75 45 79 / 100 60 20 0 0 10
Sandpoint 50 57 37 71 42 76 / 100 100 20 0 0 0
Kellogg 49 55 44 72 49 78 / 100 90 30 10 0 0
Moses Lake 51 73 46 79 50 80 / 10 0 0 0 0 10
Wenatchee 52 72 51 77 57 78 / 20 10 0 0 10 10
Omak 51 73 47 76 50 77 / 80 10 10 0 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
621 PM CDT TUE SEP 17 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 315 PM CDT TUE SEP 17 2013
THE MAIN FOCUS IS ON PRECIPITATION CHANCES TONIGHT AND HOW LONG
THEY WILL HOLD ON INTO WEDNESDAY.
LIGHT RAIN SHOWERS CONTINUE TO TRACK TO THE NORTHEAST ACROSS THE
AREA ALONG A SHARP MID LEVEL TROUGH AND WEAKENING MCV. RAINFALL
AMOUNTS HAVE BEEN LIGHT WITH THIS FEATURE AT LESS THAN A TENTH OF
AN INCH AND GUIDANCE HAS NOT DONE A VERY GOOD JOB OF PICKING UP ON
IT. THE EXCEPTION IS THE HRRR WHICH HAS HELD IT TOGETHER THROUGH
MUCH OF TODAY AND CONTINUES TO TAKE IT NORTHEAST INTO NORTH
CENTRAL WISCONSIN THIS EVENING.
WITH BROAD MID LEVEL TROUGHING REMAINING IN PLACE ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY TONIGHT AND LOW LEVEL MOISTURE TRANSPORT
INCREASING OUT OF THE CENTRAL PLAINS...EXPECT THAT SHOWERS AND A
SOME THUNDERSTORMS WILL DEVELOP AND INCREASE IN COVERAGE THROUGH THE
NIGHT. GUIDANCE HAS BEEN FAIRLY CONSISTENT WITH THE NOSE OF THIS
TRANSPORT BEING FOCUSED ACROSS SOUTHEAST MINNESOTA AND NORTHEAST
IOWA...WHICH IS ALSO WHERE THE HIGHEST INSTABILITY DEVELOPS AS
WELL. WIND SHEAR REMAINS LOW OVERNIGHT WITH INSTABILITY ALSO
STAYING ON THE LOW SIDE AND PEAKING AT ABOUT 500-1000J/KG IN
MN/IA. THUS...AM NOT EXPECTING ANY ORGANIZED CONVECTION TO OCCUR.
AS THE TROUGH SHIFTS EAST WITH UPPER LEVEL RIDGING COMING IN TOMORROW
MORNING AND THE MOISTURE TRANSPORT WEAKENS...EXPECT THAT THE
CONVECTION WILL EITHER SHIFT EAST OR DIMINISH IN COVERAGE ALLOWING
FOR A PRECIPITATION FREE DAY. IT WILL BE MUCH MORE HUMID WITH
SURFACE DEW POINTS CLIMBING INTO THE MID TO UPPER 60S. HIGH
TEMPERATURES WILL DEPEND GREATLY UPON CLOUD COVER AS THE STRATUS
IS EXPECTED TO LINGER FOR MUCH OF THE DAY. IF IT CLEARS EARLIER
THAN FORECAST...THEN TEMPS COULD BE ABOUT 4-8F HIGHER.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 315 PM CDT TUE SEP 17 2013
WITH UPPER LEVEL RIDGING IN PLACE WEDNESDAY NIGHT...HAVE GONE DRY
FOR MUCH OF THE REGION DESPITE SOME LOW LEVEL MOISTURE TRANSPORT
DEVELOPING AGAIN. THE MAIN FOCUS FOR PRECIPITATION WILL BE ALONG
THE COLD FRONT AS IT TRACKS TO THE EAST ON THURSDAY OUT AHEAD OF A
CLOSED MID LEVEL LOW. THE 17.12Z NAM CONTINUES TO BE THE FASTEST
OF THE MODEL SOLUTIONS FOR THIS FRONTAL PASSAGE AND HAS IT INTO
CENTRAL WISCONSIN BY 00Z FRIDAY WHILE THE 17.12Z GFS/ECMWF HOLD IT
BACK WEST OF THE MISSISSIPPI RIVER AT THAT SAME POINT. THE TIMING
OF THIS COLD FRONT PASSAGE WILL BE THE MAIN FACTOR WITH WHERE ANY
POTENTIAL SEVERE WEATHER COULD OCCUR. WHILE DEEP SHEAR LOOKS
WEAK...MODIFIED 17.12Z NAM/GFS SOUNDINGS WITH SURFACE DEW POINTS
IN THE UPPER 60S...RATHER THAN LOW/MID 70S...SHOW ABOUT
2000-3000J/KG OF MIXED LAYER CAPE DEVELOPING AHEAD OF THE FRONT.
IF THERE IS ANY SHEAR...ITS IN THE LOWEST 2-3KM AT ABOUT 20-30KTS
WHICH COULD HELP WITH POTENTIALLY ORGANIZING SOME OF THE
CONVECTION INTO BOWING SEGMENTS BRIEFLY.
AS THE FRONT MOVES THROUGH...PRECIPITATION IS EXPECTED TO END
OVERNIGHT INTO FRIDAY MORNING...THOUGH THE 17.12Z ECMWF HAS
DEVIATED FROM THAT WITH DEVELOPING A STRONGER SECONDARY MID LEVEL
TROUGH. THIS WOULD RUN THE PRECIPITATION LONGER AND HEAVIER THAN
WHAT WE ARE CURRENTLY FORECASTING...BUT HAVE SLOWED DOWN THE
EASTWARD PROGRESSION OF THE PRECIPITATION CHANCES A TAD.
BEYOND THAT...UPPER LEVEL RIDGING SETS UP FOR THE WEEKEND ON INTO
EARLY NEXT WEEK WITH THE REGION STAYING UNDER A COOL AIR MASS
BEFORE THE FLOW BECOMES MORE SOUTHWESTERLY TOWARD MID WEEK. WITH
LITTLE TO NO INSTABILITY AROUND FOR THE NEXT SYSTEM THAT APPEARS
TO COME IN ON MONDAY NIGHT...HAVE REMOVED THE THUNDER MENTION FOR
THAT PERIOD.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 621 PM CDT TUE SEP 17 2013
AVIATION CONDITIONS WILL BE LESS THAN IDEAL AS AIRMASS CONTINUES TO
SATURATE IN BROAD SOUTHWEST FLOW AHEAD OF LARGE UPSTREAM TROUGH.
CEILINGS AND VISIBILITIES HAVE BEEN DROPPING ACROSS SOUTHERN
MINNESOTA AND NORTHERN IOWA WITH BOUTS OF DRIZZLE OR REAL LIGHT
RAIN. ONLY MVFR CONDITIONS SO FAR IN WESTERN WISCONSIN BUT NOT MUCH
IMPROVEMENT EXPECTED TONIGHT. ADDITIONAL SHOWERS COULD DEVELOP AS
LOW LEVEL MOISTURE TRANSPORT INCREASES WHICH COULD CREATE WIDESPREAD
LIFR CONDITIONS WEST OF THE MISSISSIPPI RIVER AND DOWN TO IFR EAST.
BULK OF THIS MOISTURE TRANSPORT PEAKS OVERNIGHT THOUGH AND WITH
HINTS OF DRY PUNCH COMING IN FROM THE WEST TOMORROW...COULD SEE
IMPROVEMENT IN FLIGHT RULES BY WEDNESDAY AFTERNOON FROM WEST TO EAST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...SHEA
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
309 PM CDT MON SEP 16 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 309 PM CDT MON SEP 16 2013
THE MAIN FOCUS INTO TOMORROW IS WITH THE POTENTIAL FOR FROST
TONIGHT IN NORTH CENTRAL WISCONSIN FOLLOWED BY THE CHANCES FOR
RAIN SHOWERS TOMORROW AFTERNOON.
CURRENTLY...MID TO UPPER LEVEL RIDGING IS DRIFTING EAST INTO THE
UPPER MISSISSIPPI RIVER VALLEY WHILE AN ELONGATED SHORT WAVE
TROUGH EXTENDS FROM SOUTHWEST CANADA DOWN THE FRONT RANGE OF THE
ROCKIES THROUGH THE CENTRAL PLAINS AND MID MISSISSIPPI RIVER
VALLEY. AT THE SURFACE...A BROAD RIDGE OF HIGH PRESSURE IS
CENTERED OVER THE UPPER GREAT LAKES WITH A TROUGH/COLD FRONT OUT
ALONG THE FRONT RANGE OF THE ROCKIES. DRY AIR ASSOCIATED WITH THIS
RIDGE HAS LED TO SKIES CLEARING OUT ACROSS THE REGION WITH SOME
STRATOCUMULUS HANGING ON ACROSS CENTRAL IOWA.
EXPECT THAT SKIES WILL BE CLEAR THROUGH THE NIGHT WITH HIGH LEVEL
CLOUD COVER COMING IN TOMORROW MORNING AS THE MID LEVEL SHORT WAVE
TROUGH LIFTS TO THE NORTHEAST. LOW LEVEL WARM AIR ADVECTION WILL
BE KICKING IN TONIGHT WITH 850MB TEMPERATURES RISING FROM AROUND
6C TO 10C BY DAYBREAK. WHILE THE CLEAR SKIES AND LIGHT WINDS WILL
LEAD TO IDEAL RADIATIONAL COOLING CONDITIONS IN NORTH CENTRAL
WISCONSIN...THINKING IS THAT THE WARMING LOW LEVEL TEMPERATURES
WILL KEEP ANY FROST DEVELOPMENT RATHER PATCHY AND MAINLY IN THE
LOW LYING AREAS. SINCE IT IS NOT LOOKING TO BE VERY
WIDESPREAD...WILL NOT BE ISSUING A FROST ADVISORY FOR TONIGHT.
AS THE MID LEVEL TROUGH LIFTS NORTH TOMORROW...THE QUESTION IS IF
ANY RAIN SHOWERS WILL BE ABLE TO REACH THE GROUND DUE TO A
SUBSTANTIAL DRY LAYER AT 800MB. AS THIS LAYER CONTINUES TO BE
PRECIPITATED INTO...IT WILL EVENTUALLY SATURATE OUT THOUGH
INSTABILITY LOOKS VERY LOW THROUGH THE AFTERNOON. HAVE GONE WITH
AN INCREASING CHANCE OF RAIN SHOWERS FROM SOUTHWEST TO NORTHEAST
THROUGH THE AFTERNOON TO FOLLOW ALONG WITH THE PATH OF THE TROUGH.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 309 PM CDT MON SEP 16 2013
THE BETTER SHOT FOR SEEING ANY RAIN WILL COME IN TUESDAY NIGHT AS
LOW LEVEL MOISTURE TRANSPORT INCREASES WITH THE NOSE OF THE
925-850MB JET POKING INTO THE REGION. 0-3KM MUCAPE INCREASES TO
AROUND 500-1000J/KG AS WELL WHICH SHOULD LEAD TO SOME ISOLATED TO
SCATTERED THUNDERSTORMS OVERNIGHT. CURRENT THINKING IS THAT THE
HIGHEST RAINFALL WILL LIKELY BE ACROSS NORTHEAST IOWA WHERE UP TO
A HALF INCH OF ACCUMULATION IS POSSIBLE.
AS THE LOW LEVEL JET WEAKENS AND THE MID LEVEL SHORTWAVE TRACKS TO
THE NORTHEAST DURING THE LATE MORNING/AFTERNOON ON
WEDNESDAY...THINK THAT THERE WILL BE A BREAK IN THE RAIN ON
WEDNESDAY. HAVE BACKED DOWN ON PRECIPITATION CHANCES IN THE
AFTERNOON BUT THEN BRING THEM BACK UP AGAIN WEDNESDAY NIGHT AS THE
LOW LEVEL JET DEVELOPS AGAIN WITH ITS NOSE FOCUSED ON THE REGION.
THE THREAT FOR SEVERE WEATHER LOOKS LOW FOR TUESDAY NIGHT INTO
THURSDAY MORNING AS THE SHEAR AND INSTABILITY PROFILES LOOK
UNIMPRESSIVE. GOING INTO THURSDAY AFTERNOON...THE TIMING OF A COLD
FRONT PASSAGE IS TRENDING FASTER AND LOOKS LIKE IT WILL COME
THROUGH THE REGION DURING MID TO LATE AFTERNOON AS A CLOSED MID
LEVEL LOW APPROACHES FROM THE WEST. WITH SURFACE DEW POINTS
INCREASING TO THE UPPER 60S AHEAD OF THE FRONT...MODIFIED 16.12Z
NAM/GFS SOUNDINGS SHOW ABOUT 2000-3000J/KG OF MUCAPE DEVELOPING
AHEAD OF THE FRONT. THIS WARM SECTOR LOOKS LIKE IT IS CAPPED OFF
BY A 850MB WARM LAYER...WHICH DOES WEAKEN THE CLOSER YOU GET TO
THE FRONT. WHILE THE HIGHEST 0-6KM SHEAR STAYS BEHIND THE SURFACE
FRONT...FORECAST SOUNDINGS FROM THE 16.12Z NAM/GFS BOTH SHOW SOME
DECENT 0-3KM UNIDIRECTIONAL SHEAR AT ABOUT 30KTS WHICH COULD BE
FAVORABLE FOR SOME BOWING SEGMENTS. WILL HAVE TO MONITOR THE
TIMING OF THE FROPA TIMING AS IT HAS BOUNCED AROUND THE PAST FEW
DAYS BUT DOES SEEM TO BE SETTLING DOWN ON MID AFTERNOON AS SOME OF
THE SHORTER RANGE MODELS PICK UP ON IT. EXPECT THAT ANY CONVECTION
WOULD DEVELOP RIGHT OUT AHEAD OF THE FRONT WHERE THE CAP WEAKENS
YET INSTABILITY STAYS HIGH ALONG WITH THE DEEP LIFT.
AFTER THE FRONT MOVES THROUGH BY THURSDAY NIGHT...IT WILL JUST BE
ANOTHER STRETCH OF BELOW NORMAL TEMPERATURES GOING THROUGH NEXT
WEEKEND WITH DRY CONDITIONS AS A RIDGE OF HIGH PRESSURE BUILDS
ACROSS THE REGION WITH THE NEXT SYSTEM NOT COMING IN UNTIL PERHAPS
LATE ON MONDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1236 PM CDT MON SEP 16 2013
HIGH PRESSURE OVER NORTHERN WISCONSIN HAS KEPT SKIES MAINLY CLEAR
ACROSS MUCH OF WESTERN WISCONSIN AND SOUTHEAST MINNESOTA. THERE
IS AN EXPANSIVE AREA OF MVFR CLOUDS ACROSS MUCH OF IOWA. THESE
CLOUDS ARE ASSOCIATED WITH SOME LOW LEVEL MOISTURE WRAPPING AROUND
THE PERIPHERY OF THIS HIGH. THE RAP IS HANDLING THESE CLOUDS
FAIRLY WELL AND IT SHOWS THAT THE NORTHERN EXTENT OF THESE CLOUDS
WILL GRADUALLY DISSIPATE THIS AFTERNOON AND THEY WILL NOT AFFECT
EITHER TAF SITE. A 20-30K DECK OF CLOUDS WILL MOVE INTO THE AREA
AFTER 17.09Z...AND THEN GRADUALLY LOWER TO AROUND 12K FEET WEST OF
THE MISSISSIPPI RIVER LATE TUESDAY MORNING.
THE EAST WINDS WILL REMAIN GENERALLY LESS THAN 5 KNOTS THROUGH
THIS EVENING...AND THEN SHIFT TO THE SOUTHEAST AND INCREASE INTO
THE 5 TO 10 KNOTS FOR LATE TONIGHT AND TUESDAY MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1237 PM CDT MON SEP 16 2013
.UPDATE...
ISSUED AT 747 AM CDT MON SEP 16 2013
WILL ALLOW THE FROST ADVISORY TO EXPIRE AS SCHEDULED AT 8 AM.
TEMPERATURES WILL QUICKLY WARM INTO THE 40S ALLOWING THE FROST TO
DISSIPATE BY MID MORNING.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 236 AM CDT MON SEP 16 2013
MAIN FORECAST CONCERNS ARE ON LOW TEMPERATURES TONIGHT WITH THE
POTENTIAL FOR AREAS OF FROST OVER CENTRAL INTO NORTHERN WISCONSIN.
FOCUS THEN TURNS TO SHOWER AND THUNDERSTORM CHANCES LATE TUESDAY
THROUGH THURSDAY NIGHT.
LATEST SURFACE OBSERVATIONS SHOWED HIGH PRESSURE BUILDING INTO THE
WESTERN GREAT LAKES AND UPPER MISSISSIPPI RIVER VALLEY. A STRATUS
DECK LINGERED OVER PORTIONS OF SOUTHERN WISCONSIN THROUGH NORTHEAST
IOWA. THE STRATUS SHOULD GRADUALLY DISSIPATE THIS MORNING AS THE
HIGH BUILDS IN.
THE HIGH WILL BE IN CONTROL ACROSS THE REGION TODAY PROVIDING MOSTLY
SUNNY SKIES AND COOL HIGH TEMPERATURES. PLAN ON HIGHS RANGING FROM
THE THE LOWER 60S OVER NORTH CENTRAL WISCONSIN TO THE MID TO UPPER
60S ACROSS NORTHEAST IOWA. WILL HAVE TO KEEP A VERY CLOSE EYE ON
DEW POINTS TODAY UNDER PEAK MIXING. DRIER AIR ALOFT COULD LEAD TO
AFTERNOON DEW POINTS FALLING INTO THE LOWER 30S TO POSSIBLY THE
UPPER 20S OVER PORTIONS OF CENTRAL INTO WEST CENTRAL WISCONSIN.
THIS WOULD PRODUCE RELATIVE HUMIDITY VALUES IN THE IN THE 25 TO 30
PERCENT RANGE. THE HIGH WILL START TO SLIDE EAST LATE TONIGHT.
MOSTLY CLEAR SKIES WILL LEAD TO ANOTHER NIGHT OF CHILLY OVERNIGHT
LOWS AND THE POTENTIAL FOR AREAS OF FROST ACROSS CENTRAL
WISCONSIN. PLAN ON OVERNIGHT LOWS RANGING FROM THE LOWER 30S OVER
NORTH CENTRAL WISCONSIN TO THE LOWER TO MID 40S ACROSS NORTHEAST
IOWA. A FROST ADVISORY MAY BE NEEDED FOR LOCATIONS ALONG AND
NORTHEAST OF THE INTERSTATE 94 CORRIDOR.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 236 AM CDT MON SEP 16 2013
THE HIGH WILL SLIDE EAST OF THE REGION TUESDAY INTO WEDNESDAY AS A
SURFACE TROUGH EDGES EAST OUT OF THE PLAINS. THIS WILL PRODUCE
SOUTHERLY FLOW OVER THE UPPER MISSISSIPPI RIVER VALLEY USHERING IN A
MOIST AIRMASS...WITH PRECIPITABLE WATER VALUES INCREASING TO 1.4 TO
1.6 INCHES. ALSO...FLOW ALOFT WILL START TO TURN SOUTHWEST BRINGING
A SERIES OF SHORTWAVE TROUGHS OVER THE REGION. 850 MB MOISTURE
TRANSPORT INCREASES ALONG AND WEST OF THE MISSISSIPPI RIVER LATE
TUESDAY AFTERNOON THEN CONTINUES TO INCREASE AND FOCUSES ACROSS MUCH
OF THE FORECAST AREA TUESDAY NIGHT. SHOWERS AND THUNDERSTORMS ARE
LIKELY ACROSS MUCH OF THE AREA FROM TUESDAY NIGHT INTO EARLY
WEDNESDAY MORNING. THE MOIST AIRMASS AND SOUTHWEST FLOW WILL PERSIST
OVER THE REGION WEDNESDAY INTO WEDNESDAY NIGHT WITH CONTINUED
CHANCES FOR SHOWERS AND THUNDERSTORMS. A VIGOROUS TROUGH MOVES ACROSS
THE NORTHERN PLAINS ON WEDNESDAY AND IS EXPECTED TO PUSH INTO THE
UPPER MISSISSIPPI RIVER VALLEY THURSDAY INTO THURSDAY NIGHT.
MEANWHILE SURFACE LOW PRESSURE WILL DEEPEN OVER SOUTHWEST
ONTARIO...LIFTING NORTHEAST TOWARD HUDSON BAY THURSDAY NIGHT INTO
EARLY FRIDAY MORNING. THIS WILL DRIVE A COLD FRONT ACROSS THE AREA
BRINGING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WITH IT. MUCH OF
THE STRONGER SHEAR LAGS BEHIND THE FRONT INITIALLY LATE THURSDAY
AFTERNOON BUT THEN APPEARS TO CATCH UP THURSDAY EVENING AS THE FRONT
MOVES INTO THE REGION. WILL HAVE TO KEEP A CLOSE WATCH ON THE
POTENTIAL FOR STRONG TO PERHAPS SEVERE THUNDERSTORMS. THE TIMING OF
THE COLD FRONT ACROSS THE AREA WOULD BE UNFAVORABLE FOR SEVERE
WEATHER BUT GIVEN THE DYNAMICS OF THE SYSTEM CANNOT RULE SEVERE
WEATHER OUT AT THIS TIME. THE UPPER LOW LOOKS TO TRACK ACROSS
SOUTHERN CANADA OR NORTHERN WISCONSIN FRIDAY INTO FRIDAY NIGHT
EFFECTIVELY DRY SLOTTING THE FORECAST AREA. THIS WILL LEAD TO
BREEZY WESTERLY WINDS ACROSS THE FORECAST AREA AND PARTLY TO MOSTLY
SUNNY SKIES. AFTER A BRIEF WARM UP WEDNESDAY INTO THURSDAY...WITH
HIGHS CLIMBING INTO THE UPPER 70S TO LOWER 80S...LOOK FOR HIGH
TEMPERATURES TO FALL BACK INTO THE 70S ON FRIDAY. HIGH PRESSURE
SHOULD GRADUALLY BUILD IN LATE FRIDAY INTO THE WEEKEND PROVING DRY
AND QUIET WEATHER. WILL HAVE TO KEEP A CLOSE EYE ON THE POTENTIAL
FOR SOME RAIN SHOWERS OVER FAR NORTHERN WISCONSIN FRIDAY NIGHT INTO
EARLY SATURDAY MORNING WITH THE PASSAGE OF THE UPPER TROUGH.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1236 PM CDT MON SEP 16 2013
HIGH PRESSURE OVER NORTHERN WISCONSIN HAS KEPT SKIES MAINLY CLEAR
ACROSS MUCH OF WESTERN WISCONSIN AND SOUTHEAST MINNESOTA. THERE
IS AN EXPANSIVE AREA OF MVFR CLOUDS ACROSS MUCH OF IOWA. THESE
CLOUDS ARE ASSOCIATED WITH SOME LOW LEVEL MOISTURE WRAPPING AROUND
THE PERIPHERY OF THIS HIGH. THE RAP IS HANDLING THESE CLOUDS
FAIRLY WELL AND IT SHOWS THAT THE NORTHERN EXTENT OF THESE CLOUDS
WILL GRADUALLY DISSIPATE THIS AFTERNOON AND THEY WILL NOT AFFECT
EITHER TAF SITE. A 20-30K DECK OF CLOUDS WILL MOVE INTO THE AREA
AFTER 17.09Z...AND THEN GRADUALLY LOWER TO AROUND 12K FEET WEST OF
THE MISSISSIPPI RIVER LATE TUESDAY MORNING.
THE EAST WINDS WILL REMAIN GENERALLY LESS THAN 5 KNOTS THROUGH
THIS EVENING...AND THEN SHIFT TO THE SOUTHEAST AND INCREASE INTO
THE 5 TO 10 KNOTS FOR LATE TONIGHT AND TUESDAY MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
UPDATE...04
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...BOYNE
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1205 PM CDT MON SEP 16 2013
.UPDATE...QUIET DAY WITH SFC HIGH PRESSURE JUST ABOUT CENTERED
OVER EASTERN LAKE SUPERIOR. VIS SAT SHOWS LAKE EFFECT DRIVEN
CLOUDS STREAMING INTO THE LAKE SHORE COUNTIES FROM LAKE MICHIGAN
AND GREEN BAY...AND DIURNALLY DRIVEN CU DEVELOPING IN EASTERN
WISCONSIN.
THE GOES-R PG ABI SYNTHETIC SAT IMAGERY BASED OFF THE NSSL WRF IS
CAPTURING MUCH OF THE LAKE EFFECT DRIVEN CLOUDS. THOUGH NOT SO
WELL WITH THE LOW LEVEL CLOUDS IN IA AND IL OR THE DIURNAL CU THAT
IS DEVELOPING. RAP BUFKIT THERMODYNAMIC DIAGRAMS FURTHER SUPPORT
THE DEVELOPMENT OF DIURNAL CU GIVEN LINGERING LOW-LEVEL MOISTURE
AND THE TEMPERATURE PROFILES.
CONSIDERING THE QUICK DEVELOPMENT ALREADY...EXPECT ADDITIONAL CU
TO DEVELOP ACROSS THE FORECAST AREA FROM EAST TO WEST. THIS WILL
COINCIDE WITH THE LAKE EFFECT DRIVEN CLOUDS PUSHING WEST WITH
TIME. AS SUCH...INCREASED SKY COVER IN THE FORECAST FOR TODAY AND
UPDATE THE SKY COVER FORECAST TRENDS.
ET
&&
.AVIATION/18Z TAFS/...MVFR/VFR CEILINGS ARE EXPECTED THIS
AFTERNOON...WITH VFR CONDITIONS TONIGHT AND TUESDAY. LOW CONFIDENCE
WITH MVFR CLOUDS MOVING INTO THE AREA LATER TONIGHT INTO TUESDAY.
HIGH PRESSURE WILL SHIFT SOUTHEAST ACROSS THE WESTERN GREAT LAKES
REGION THIS AFTERNOON INTO TUESDAY. GUSTY NORTHEAST WINDS WILL
LINGER AT THE EASTERN TAF SITES THIS AFTERNOON...WITH WEAKER WINDS
AT MADISON. MVFR/VFR CEILINGS WITH DIURNAL CUMULUS AND LAKE EFFECT
CLOUDS WILL LINGER THIS AFTERNOON...BEFORE DISSIPATING BY EARLY
EVENING.
WINDS WILL VEER TO THE EAST AND REMAIN LIGHT TONIGHT...AND
SOUTHEAST AND INCREASE A BIT ON THURSDAY. LOW CONFIDENCE WITH MVFR
CEILINGS MOVING INTO THE AREA LATER TONIGHT INTO TUESDAY MORNING
FROM THE SOUTHEAST. WILL NOT MENTION THE MVFR CEILINGS IN TAFS AT
THIS TIME.
WOOD
&&
.MARINE...SMALL CRAFT ADVISORY CONTINUES FOR THE NEARSHORE WATERS
OF LAKE MICHIGAN THIS AFTERNOON INTO THIS EVENING. NORTHEAST WINDS
WILL CONTINUE TO GUST TO AROUND 22 KNOTS INTO THE EARLY AFTERNOON
HOURS. WINDS WILL THEN GRADUALLY WEAKEN INTO THE EVENING...AS THE
PRESSURE GRADIENT WEAKENS AND LOW LEVEL MIXING SUBSIDES.
HIGH WAVES OF 4 TO 8 FEET WILL REMAIN HIGH THROUGH THE
AFTERNOON...BEFORE GRADUALLY SUBSIDING THIS EVENING. MAY HAVE TO
EXTEND SMALL CRAFT ADVISORY IN THE NORTHERN TWO MARINE ZONES INTO
THE EVENING TO ACCOUNT FOR POSSIBLE LINGERING HIGH WAVES.
A SMALL CRAFT ADVISORY MAY BE NEEDED FOR TUESDAY INTO WEDNESDAY
NIGHT...WITH ONSHORE WINDS GENERATING HIGH WAVES. TIGHTENING
PRESSURE GRADIENT WITH WARMER AIRMASS MOVING INTO THE REGION MAY
BRING STRONG ENOUGH ONSHORE WINDS TO GENERATE THE HIGH WAVES.
WOOD
&&
.PREV DISCUSSION... /ISSUED 333 AM CDT MON SEP 16 2013/
SHORT TERM...
TODAY AND TONIGHT...FORECAST CONFIDENCE IS HIGH.
COLD ADVECTION LOW CLOUDS GRADUALLY ERODING FROM NORTH TO SOUTH AS
DRY AIR WORKS INTO THE REGION AHEAD OF STRONG HIGH PRESSURE BUILDING
ACROSS WISCONSIN THIS MORNING. MODELS ARE IN GENERAL AGREEMENT THAT
MOST PLACES AWAY FROM THE LAKE MI COUNTIES WILL BE SEE SUNSHINE BY
OR SHORTLY AFTER SUNRISE. TRAJECTORIES AND ELEVATED DELTA-T/S WILL
KEEP PLENTY OF CLOUDS AND AN ISOLATED THREAT OF LAKE EFFECT SHOWERS
IN THE FAR SOUTHEAST THROUGH THE MORNING. THE CLOUDS SHOULD
GRADUALLY ERODE ACROSS THIS AREA BY EARLY AFTERNOON. DESPITE THE
SUNSHINE...TEMPS WILL BE ON THE CHILLY SIDE...ONLY THE LOWER TO MID
60S.
ALL QUIET TONIGHT...BUT COLD WITH LOWS IN THE UPPER 30S TO LOWER 40S
AWAY FROM THE LAKE. AN ONSHORE FLOW WILL KEEP TEMPS WARMER BY THE
LAKE MICHIGAN SHORE.
TUESDAY...FORECAST CONFIDENCE HIGH.
HIGH PRESSURE OVER THE GREAT LAKES WILL DRIFT EAST. LOOK FOR GRADUAL
WARMING WITH SOUTHEAST WINDS WITH RETURN FLOW AROUND THE HIGH. THE
SOUTHEAST WINDS WILL KEEP TEMPS LOWER IN THE MID 60S NEAR THE
LAKESHORE. 925MB TEMPS WILL ONLY BE AROUND 14C INLAND...SO MAX TEMPS
WILL BE LIMITED TO AROUND 70.
QUITE A STRONG MID LEVEL SHORTWAVE TROUGH WILL CROSS WI TUE
AFTERNOON...BUT THE ATMOSPHERE WILL BE TOO DRY FOR ANY PRECIP.
TUESDAY NIGHT AND WEDNESDAY...FORECAST CONFIDENCE MEDIUM TO HIGH.
THAT INITIAL SHORTWAVE MOVES OFF TO THE EAST BUT A WEAKER SHORTWAVE
WILL APPROACH WI TUE NIGHT INTO WED MORNING AND COINCIDE WITH THE
NOSE OF A LOW LEVEL JET AND 850MB WARM AIR ADVECTION TO PRODUCE
ELEVATED SHOWER AND ISOLATED THUNDERSTORM CHANCES. PRECIPITABLE
WATER VALUES SURGE UP TO AROUND 1.5 WHICH IS 2 STANDARD DEVIATIONS
ABOVE NORMAL. OVERALL FORCING IS PRETTY WEAK SO TRENDED POPS
DOWNWARD...ESPECIALLY WED AFTERNOON.
DESPITE A GOOD DEAL OF CLOUD COVER...TEMPS SHOULD CREEP UP INTO THE
MID/UPPER 70S.
LONG TERM...
WEDNESDAY NIGHT AND THURSDAY...FORECAST CONFIDENCE MEDIUM.
A DEEP MID LEVEL TROUGH WILL DIG ACROSS THE NORTHERN PLAINS MID WEEK
AND THE ASSOCIATED SURFACE LOW WILL CROSS NORTHERN NORTH DAKOTA WED
NIGHT. THE HIGH PRECIPITABLE WATER IN THE WARM SECTOR...NOSE OF THE
LLJ AND WEAK RIPPLES IN THE 500MB FLOW COULD LEAD TO ELEVATED
THUNDERSTORMS. THERE IS UNCERTAINTY IN THE TIMING OF THE
SHORTWAVE...SO NAM AND GFS TAPER OFF THUNDERSTORMS DURING THE DAY
THU WHILE THE ECMWF KEEPS THEM GOING. THE CANADIAN MODEL IS RIGHT IN
BETWEEN. WHILE WED NIGHT LOOKS LIKE A DECENT CHANCE FOR SOME
PRECIP...COVERAGE IS STILL QUESTIONABLE. LOWERED FORECAST POPS A
LITTLE.
THURSDAY NIGHT...FORECAST CONFIDENCE MEDIUM TO HIGH.
THE ASSOCIATED LEADING SURFACE TROUGH OF THE OCCLUDING SYSTEM WILL
REACH SOUTH CENTRAL WI AROUND 00Z FRI. THIS FEATURE IS OUT AHEAD OF
THE MAIN UPPER TROUGH/VORT MAX. WEAKER SHORTWAVE ENERGY AND THE
ENTRANCE REGION OF THE UPPER JET WILL SUPPORT THUNDERSTORMS.
ASSUMING DEWPOINTS GET INTO THE UPPER 60S ON THU...THERE COULD BE
1500 J/KG OF CAPE THU EVENING. CAPE DWINDLES QUICKLY THU NIGHT...AND
SHEAR REMAINS FAIRLY LOW...SO ANY STRONGER STORMS COULD PRODUCE
HIGHER WIND GUSTS...BUT NOT EXPECTING SEVERE. NONETHELESS...THIS
APPEARS TO BE OUR NEXT BEST CHANCE FOR MORE WIDESPREAD THUNDERSTORM
ACTIVITY.
FRIDAY THROUGH MONDAY...FORECAST CONFIDENCE MEDIUM TO HIGH.
AN UPPER LEVEL RIDGE WILL BUILD INTO THE NORTHERN PLAINS AS THE
STRONG UPPER LOW MOVES TOWARD THE NORTHEAST. THIS WILL BRING QUIET
WEATHER TO SOUTHERN WI FOR THE WEEKEND.
CLOUDS AND POSSIBLY A FEW LIGHT SHOWERS COULD LINGER FRIDAY MORNING
AND PAST MODEL RUNS HAVE HINTED AT CYCLONIC FLOW HANGING AROUND THE
UPPER GREAT LAKES THROUGH AS LATE AS SATURDAY...SO WILL NEED TO KEEP
AN EYE ON THIS. THE ECMWF WOULD SUGGEST WARMER TEMPS FOR SATURDAY
AND SUNDAY THAN THE GFS.
THE WEATHER WILL REMAIN QUIET UNTIL THE NEXT LOW PRESSURE SYSTEM
MOVES THROUGH THE NORTHERN PLAINS AND REACHES WI MONDAY
AFTERNOON/EVENING.
AVIATION/12Z TAFS/...
MORNING LOW CLOUDS WILL CLEAR OUT QUICKLY EARLY THIS MORNING AWAY
FROM LAKE MICHIGAN. AN ONSHORE NORTHEAST WIND FLOW AND ELEVATED
DELTA-T/S OVER THE LAKE WILL KEEP THE MVFR CIGS IN KMKE/KENW/KUES
THROUGH MUCH OF THE MORNING...THEN CLEARING DURING THE AFTERNOON.
VFR CONDITIONS WILL THEN CONTINUE THROUGH TONIGHT.
MARINE...
SMALL CRAFT ADVISORY CONTINUES FOR THE NEARSHORE WATERS INTO THIS
EVENING. BRISK NORTHEAST WINDS AND WAVES TO 4 TO 7 FEET WILL
CONTINUE INTO THE AFTERNOON. THE WINDS AND WAVES WILL GRADUALLY
DIMINISH DURING THE AFTERNOON...FALLING BELOW ADVISORY LEVELS THIS
EVENING.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LMZ645-646.
SMALL CRAFT ADVISORY UNTIL 6 PM CDT THIS EVENING FOR LMZ643-644.
&&
$$
UPDATE...ET/WOOD
TODAY/TONIGHT AND AVIATION/MARINE...DAVIS
TUESDAY THROUGH SUNDAY...MRC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1148 PM CDT SUN SEP 15 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 301 PM CDT SUN SEP 15 2013
THE MAIN FOCUS INTO TOMORROW IS WITH HOW LONG THE LOW LEVEL CLOUD
COVER WILL LINGER WHICH WILL AFFECT HOW MUCH TEMPERATURES CAN DROP
TONIGHT.
CURRENTLY...AN EXPANSIVE STRATOCUMULUS DECK TRAPPED UNDER AN
INVERSION AROUND 850MB IS IN PLACE ACROSS MUCH OF THE UPPER
MISSISSIPPI RIVER VALLEY ON UP TO CENTRAL MINNESOTA. THE MAIN
CLEARING COMES AS YOU APPROACH THE CORE OF A SURFACE HIGH THAT IS
CENTERED OVER SOUTHERN MANITOBA. SOME HOLES HAVE WORKED IN AS WELL
AND EXPECT THAT AS THIS HIGH DROPPING SOUTH TONIGHT...SKIES WILL
CLEAR OUT AS THIS DRIER AIR COMES IN. CONFIDENCE IS NOT THE
HIGHEST IN WHEN THE WIDESPREAD CLEARING WILL GET IN AS THE 15.12Z
NAM/GFS AND 15.18Z RAP ALL SUGGEST DIFFERENT TIMING WITH WHEN THE
LOW LEVEL RH DROPS. BOTH THE NAM AND GFS SHOW THE QUICK DROP IN LOW
LEVEL RH THIS EVENING WHERE AS THE PAST FEW RUNS OF THE RAP
SHOWING SOME HIGHER RH HOLDING ON OVERNIGHT...PARTICULARLY IN
NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN. THIS CLOUD COVER WILL
HELP TO KEEP TEMPERATURES DOWN GOING INTO THE EVENING AND AS IT
CLEARS IT WILL ALLOW FOR SOME IDEAL RADIATIONAL COOLING WITH WINDS
DROPPING DOWN AS WELL. CONSIDERED BRINGING THE FROST ADVISORY
FURTHER SOUTH INTO THE BOG/LOW LYING AREAS OF
JACKSON/MONROE/JUNEAU/ADAMS COUNTIES THAT TYPICALLY ARE ABOUT 10F
COOLER THAN ITS SURROUNDINGS...BUT CONFIDENCE IS NOT HIGH ON HOW
LONG TEMPERATURES WOULD BE DOWN THAT LOW TO DEVELOP A WIDESPREAD
FROST.
OTHERWISE...IT WILL BE A PLEASANT DAY WEATHER-WISE ON MONDAY AS
THE SURFACE HIGH CONTINUES TO DROP SOUTH AND PROVIDE CLEAR
SKIES...LIGHT WINDS AND HIGHS IN THE MID TO UPPER 60S.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 301 PM CDT SUN SEP 15 2013
THE MAIN FOCUS THROUGH THE REST OF THE WEEK IS WITH THE
RAIN/THUNDER CHANCES TUESDAY THROUGH FRIDAY MORNING.
AFTER THE RIDGE OF HIGH PRESSURE SHIFTS TO THE EAST ON TUESDAY...A
MID LEVEL TROUGH CURRENTLY STALLED OUT OVER THE CENTRAL ROCKIES
WILL TRACK TO THE EAST AND PROVIDE SOME WEAK MID TO UPPER LEVEL
LIFT TUESDAY INTO EARLY WEDNESDAY. INSTABILITY LOOKS LIKE IT
REMAINS RATHER WEAK ON TUESDAY BUT THEN INCREASES TUESDAY NIGHT
AND WEDNESDAY AS THE LOW LEVEL MOISTURE TRANSPORT INCREASES.
OVERALL LIFT LOOKS RATHER WEAK FOR THIS SYSTEM...BUT IT MAY BE
ENOUGH THAT WITH SOME DECENT MOISTURE THAT THERE WILL BE SOME
SCATTERED SHOWERS AND A FEW NON-SEVERE STORMS THAT DEVELOP.
THE MORE IMPRESSIVE LOOKING SYSTEM IS WITH WHAT COMES IN ON
THURSDAY NIGHT. A CLOSED MID LEVEL LOW FORMS ACROSS THE DAKOTAS
ON THURSDAY THAT APPEARS TO BECOME NEGATIVELY TILTED THURSDAY
NIGHT PER THE 15.12Z GFS/GEM. THE 15.12Z ECMWF IS A LITTLE SLOWER
WITH THIS TROUGH BUT DOES SHOW SOME NEGATIVE TILT WITH THE INITIAL
SHORT WAVE THAT COMES THROUGH EARLY ON FRIDAY. AT THE SURFACE...A
DEEPENING LOW PRESSURE SYSTEM WILL TRACK THROUGH SOUTHERN CANADA
AS A COLD FRONT COMES THROUGH ON THURSDAY NIGHT. WILL HAVE TO
WATCH THIS FEATURE FOR THE POTENTIAL OF SOME SEVERE WEATHER BUT AT
THE MOMENT THE NOCTURNAL TIMING DOES NOT LOOK TO BE THE GREATEST.
COOLER TEMPERATURES WILL ENSUE AS WINDS COME AROUND TO THE
NORTHWEST BEHIND THE FRONT WITH THE LOW TRACKING TOWARD HUDSON
BAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1148 PM CDT SUN SEP 15 2013
NORTHEAST FLOW COMING AROUND HIGH PRESSURE IN NORTHWEST WISCONSIN
IS BRINGING DRIER AIR IN AT THE SURFACE INTO THE TAF SITES. THIS
DRIER SURFACE AIR SHOULD PRECLUDE ANY FOG DEVELOPMENT THIS MORNING.
THE OTHER ISSUE AT LEAST FOR THE EARLY MORNING HOURS IS SOME
LINGERING MVFR TO VFR STRATUS OVER SOUTHERN WISCONSIN. CONTINUED
DEEPER DRY AIR SEEN OVER NORTHERN WISCONSIN SHOULD HELP BREAK UP
THE STRATUS AT LSE AROUND 09Z WITH COMPLETE CLEARING BY 14Z. THE
VALLEY LOCATION OF LSE SHOULD HELP TO KEEP CEILINGS VFR. AT
RST...SOME SCATTERED MVFR CLOUDS ARE POSSIBLE...BEING NEAR THE
WESTERN EDGE OF THE STRATUS SHIFTING SOUTHWESTWARD. THESE TOO
SHOULD CLEAR OUT BY 13-14Z. AFTER 14Z...PLENTIFUL DRY AIR WILL BE
IN PLACE THROUGH TONIGHT TO MAINTAIN VFR CONDITIONS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FROST ADVISORY UNTIL 8 AM CDT MONDAY FOR WIZ017-029.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
444 AM MDT MON SEP 16 2013
.SHORT TERM...(TODAY AND TUESDAY NIGHT)
ISSUED AT 332 AM MDT MON SEP 16 2013
THE LONG WAITED BREAK IN THE WET WEATHER IS ON ITS WAY. SHORTWAVE
OVER SOUTHEAST WYOMING THIS MORNING WILL LIFT NORTHEAST TODAY
WHILE BEING SHEARED. MOIST SOUTHERLY FLOW AND WEAK FORCING
ASSOCIATED WITH THE SHORTWAVE WILL PRODUCE SOME LIGHT DRIZZLE THIS
MORNING IN THE PLAINS. THE DRIZZLE WILL END BY LATE THIS MORNING
AS THE BOUNDARY LAYER MIXES AND DRIER AIR PUNCHES IN FROM THE
WEST. THERE IS A CHANCE OF A FEW SHOWERS AND THUNDERSTORMS THIS
AFTERNOON...MAINLY OVER AND NEAR THE MOUNTAINS. SUBSIDENCE BEHIND
THE SHORTWAVE WILL LIMIT OVERALL PRECIPITATION CHANCES THIS
AFTENOON BUT THERE MAY BE ENOUGH INSTABILITY AND RISIDUAL BOUNDARY
LAYER MOISTURE TO POP ISOLATED CONVECTION INTO THE PLAINS LATE
THIS AFTERNOON. EITHER WAY...CHANCES FOR SHOWERS AND THUNDERSTORMS
WILL QUICKLY SUBSIDE THIS EVENING AS SUBSIDENCE AND DRY WESTERLY
FLOW ALOFT SHUT DOWN ANY PRECIPITATION.
TUESDAY WILL START OFF WITH CLEAR SKIES AND TEMPERATURES MOSTLY IN
THE 50S. DRY WEST FLOW WILL ALLOW TEMPERATURES TO WARM NICELY WITH
HIGHS IN THE 70S WEST TO 80S INTO THE PLAINS. MAY EVEN SEE ONE OR
TWO 90 DEGREE READINGS IN THE NEBRASKA PANHANDLE. MODELS ARE
SHOWING A QUICK MOVING SHORTWAVE AFFECTING THE WESTERN CWA BY
LATE TUESDAY AFTERNOON AND EVENING. THIS WAVE COULD TRIGGER SOME
SHOWERS OR WEAK THUNDERSTORMS OVER THE HIGHER ELEVATIONS OF
SOUTHEAST WYOMING LATE IN THE DAY WITH SOME ACTIVITY SHIFTING INTO
THE PLAINS DURING THE EVENING. NOT EXPECTING MUCH IN THE WAY OF
PRECIPIATION AS MOISTURE WILL BE LIMITED AT BEST.
.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 332 AM MDT MON SEP 16 2013
RATHER PROGRESSIVE PATTERN IN THE LONG TERM WITH THE MODELS
CONTINUING TO ADVERTISE PERIODS OF WARM AND BREEZY SOUTHWEST WINDS
FOLLOWED BY COOLER AND CALMER DAYS. UPPER LEVEL TROUGH WILL SCOOT
ACROSS MONTANA ON WEDNESDAY WITH A SFC LOW DEVELOPING DURING THE
AFTN ACROSS WESTERN NORTH DAKOTA. THIS STRENGTHENS THE PRESSURE
GRADIENT WITH SOUTHWEST WINDS BECOMING QUITE BREEZY ALONG AND WEST
OF THE LARAMIE RANGE. CURRENTLY APPEARS THAT GUSTS TO 40 MPH WILL
BE POSSIBLE. DRY FRONTAL PASSAGE OCCURS BY LATE WEDNESDAY NIGHT
WITH 700MB TEMPS DROPPING ABOUT 8C ON THURSDAY. TEMPS WILL BE MORE
SEASONAL BEHIND THE FRONT AND WINDS WILL DROP OFF BY THURSDAY AFTN
AS THE SFC HIGH MOVES OVERHEAD. THURSDAY NIGHT WILL LIKELY BE THE
COOLEST NIGHT OF THE FALL SO FAR WITH WEAK WINDS AND CLEAR SKIES
RESULTING IN GREAT RADIATIONAL COOLING.
BRIEF UPPER LEVEL RIDGING IS OVER THE REGION ON FRIDAY AHEAD OF
THE NEXT SYSTEM THAT IS PROGGED TO AMPLIFY ACROSS THE WESTERN
STATES ON SATURDAY. THIS WAVE WEAKENS AND LIFTS NORTHEASTWARD OVER
NORTHERN WY BY LATER SATURDAY AND SUNDAY. PRESSURE FALLS AHEAD OF
THE SYSTEM WILL CAUSE SOUTHWEST WINDS TO INCREASE ONCE
AGAIN...WITH OCCASIONAL GUSTS TO 40 MPH TO THE WEST OF THE LARAMIE
RANGE. SIMILAR TO THE MIDWEEK TROUGH...THE BEST DYNAMICS AND MOISTURE
WILL BE TO THE NORTH OF AREA...SO PRECIP CHANCES AND CLOUD COVER
WILL BE MINIMAL WITH THE TROUGH PASSAGE
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY EVENING)
ISSUED AT 1103 PM MDT SUN SEP 15 2013
LATEST 11-3.9U SATELLITE IMAGERY SHOWING LOW CLOUDS ADVECTING
NORTH OUT OF NORTHEASTERN COLORADO INTO THE PANHANDLE. THIS
MATCHES UP WELL WITH THE LATEST HRRR FORECAST FOR LOWERING
CEILINGS IN THE PANHANDLE. MOST OF THE PANHANDLE SHOULD FALL INTO
THE IFR CATEGORY AFTER 08Z. THE EXCEPTION BEING KCDR...WHO MIGHT
BE MORE LIKE 10-11Z OR SO. STRATUS LOOKS TO LAST THROUGH THE
16-17Z TIME FRAME BEFORE LIFTING.
&&
.FIRE WEATHER...
ISSUED AT 332 AM MDT MON SEP 16 2013
WET WEATHER WILL FINALLY GIVE WAY TO DRIER CONDITIONS AS THE WEATHER
PATTERN SEES A SIGNIFICANT CHANGE. WILL START OF THIS MORNING WITH
SOME FOG AND DRIZZLE ALONG AND EAST OF THE SOUTHERN LARAMIE RANGE
AND INTO THE SOUTHERN NEBRASKA PANHANDLE BUT THE FOG WILL LIFT AS
DRIER AIR PUSHES IN FROM THE WEST. COULD SEE A FEW SHOWERS AND
THUNDERSTORMS THIS AFTERNOON WITH THE MAIN CHANCES ALONG AND NEAR
THE MOUNTAINS OF SOUTHEAST WYOMING. CLEAR SKIES TO SET IN ACROSS THE
FORECAST AREA TONIGHT. A QUICK MOVING SYSTEM WILL APPROACH LATE
TUESDAY WITH WITH AFTERNOON SHOWERS AND THUNDERSTORMS POSSIBLE IN
THE WESTERN FORECAST AREA WITH DRY CONDITIONS EAST.
GUSTY WINDS TUESDAY NIGHT WEST OF THE LARAMIE RANGE WITH GUSTY WINDS
SPREADING ACROSS THE AREA WEDNESDAY. ABOVE NORMAL TEMPERATURES FOR
WEDNESDAY BUT THEN A COLD FRONT TO MOVE THROUGH WEDNESDAY NIGHT. A FEW
SHOWERS POSSIBLE WITH THE FRONTAL PASSAGE BUT CHANCES FOR WETTING RAINS
LOOKS MINIMAL AT THIS TIME.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM...LIEBL
LONG TERM...FINCH
AVIATION...CLAYCOMB
FIRE WEATHER...LIEBL
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1107 PM MDT SUN SEP 15 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 344 PM MDT SUN SEP 15 2013
SHOWERS CONTINUE EARLY THIS AFTERNOON OVER THE SOUTHWEST QUARTER
OF THE CWA. ISOLATED STORMS HAVE ALSO DEVELOPED OVER SOUTH CENTRAL
WYOMING. THE HEAVIER RAINFALL WAS ALONG THE NORTHERN FRONT RANGE
OF COLORADO AS OF 20Z. ALL OF THE ACTIVITY WAS CURRENTLY MOVING
SLOWLY NORTH. ALTHOUGH RAINFALL RATES HAVE NOT BEEN LARGE SINCE MID
MORNING OVER AND NEAR THE SOUTHERN LARAMIE RANGE...THEY SHOULD
INCREASE LATE THIS AFTERNOON AND EARLY THIS EVENING. WILL EXTEND
THE FLASH FLOOD WATCH PREVIOUSLY ISSUED UNTIL 03Z. THE RAINFALL
IS BEING PRODUCED BY AN UPSTREAM SHORTWAVE TROUGH LIFTING SLOWLY
NORTHEAST AS WELL AS SURFACE UPSLOPE WIND FLOW. MOISTURE WILL ALSO
STILL BE ABUNDANT OVER THE AREA. THE RAINFALL SHOULD DECREASE AND
END LATER TONIGHT AS THE SURFACE FORCING WEAKENS. THE ABUNDANT LOW
LEVEL MOISTURE WILL HELP TO KEEP LOW CLOUDS OVER MUCH OF THE CWA
ALONG WITH FOG IN SOME AREAS. THE INCREASING SOUTHERLY SURFACE
PRESSURE GRADIENT SHOULD ALLOW FOR MORE STRATUS AND ONLY LIGHT FOG.
WILL ALSO CANCEL THE DENSE FOG ADVISORY WITH FORECAST ISSUANCE AS
FOG HAS DISSIPATED OVER ALL BUT THE HIGHER ELEVATIONS OF THE
SOUTHERN LARAMIE RANGE AS OF 20Z.
THE SHORTWAVE TROUGH AS WELL AS A DEVELOPING SURFACE TROUGH OVER
EASTERN WYOMING WILL HELP FORM SOME SHOWERS AND THUNDERSTORMS
OVER MUCH OF THE CWA MONDAY AFTERNOON AND EARLY EVENING. THE
PRECIPITABLE WATER VALUES WILL STILL BE AROUND AN INCH AHEAD OF THE
SHORTWAVE TROUGH...SO SOME OF THE STORMS OVER THE EAST PART OF THE
CWA COULD PRODUCE A PERIOD OF HEAVY RAINFALL.
OTHERWISE...HEIGHTS ALOFT RISE OVER THE CWA THROUGH 00Z WEDNESDAY.
THE RESULT WILL BE WARMER AND DRIER WEATHER. GUSTY DAYTIME
SOUTHWEST SURFACE WINDS CAN ALSO BE EXPECTED IN AREAS ALONG AND
WEST OF THE LARAMIE RANGE BOTH MONDAY AND TUESDAY.
CLOUDS WILL INCREASE ON TUESDAY AHEAD OF THE NEXT SHORTWAVE TROUGH
CURRENTLY JUST OFF THE PACIFIC NORTHWEST COAST. SOME AFTERNOON
SHOWERS AND THUNDERSTORMS WILL ALSO FORM MAINLY OVER AND WEST OF
THE LARAMIE RANGE.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 344 PM MDT SUN SEP 15 2013
PROGRESSIVE UPPER LEVEL TROUGH WILL MOVE ACROSS THE ROCKIES ON
WEDNESDAY WITH A COLD FRONT MOVING THROUGH THE FORECAST AREA
WEDNESDAY EVENING. AHEAD OF THE FRONT...LOOKING AT WARM AND WINDY
CONDITIONS...ESPECIALLY FOR THE WIND PRONE REGIONS OUT WEST.
MOISTURE CONTINUES TO LOOK MEAGER WITH THIS SYSTEM...BUT MAINTAINED
CHANCE POPS IN THE MOUNTAINS AND SLIGHT CHANCE POPS FOR THE PLAINS
WITH THE FRONT. SHOULD SEE A FEW THUNDERSTORMS DEVELOP AHEAD OF THE
FRONT AS WELL WITH CAPE VALUES PROGGED TO INCREASE TO AROUND 500
J/KG IN THE LATE AFTERNOON. TROUGH AXIS WILL MOVE OVERHEAD ON
THURSDAY...BRINGING COOLER TEMPS AND CONTINUED WINDY CONDITIONS
ALONG AND WEST OF THE LARAMIE RANGE AS HIGH PRESSURE BEGINS TO
BUILD IN FROM THE WEST. MAY SEE A FEW SHOWERS IN THE MOUNTAINS
WITH WESTERLY UPSLOPE FLOW AND COOLER TEMPS ALOFT...OTHERWISE WILL
REMAIN DRY. DRY ZONAL FLOW WILL BE OVERHEAD ON FRIDAY WITH TEMPS
WARMING 5 TO 10 DEGREES. EVEN WARMER TEMPS ARE EXPECTED FOR
SATURDAY AS THE NEXT UPPER LEVEL SYSTEM DIGS INTO THE WESTERN
CONUS AND AMPLIFIES THE DOWNSTREAM RIDGE. A FEW MOUNTAIN TSTORMS
ARE POSSIBLE IN THE LATE AFTERNOON IN THIS PATTERN...OTHERWISE
LOOKS TO REMAIN BREEZY AND DRY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY EVENING)
ISSUED AT 1103 PM MDT SUN SEP 15 2013
LATEST 11-3.9U SATELLITE IMAGERY SHOWING LOW CLOUDS ADVECTING
NORTH OUT OF NORTHEASTERN COLORADO INTO THE PANHANDLE. THIS
MATCHES UP WELL WITH THE LATEST HRRR FORECAST FOR LOWERING
CEILINGS IN THE PANHANDLE. MOST OF THE PANHANDLE SHOULD FALL INTO
THE IFR CATEGORY AFTER 08Z. THE EXCEPTION BEING KCDR...WHO MIGHT
BE MORE LIKE 10-11Z OR SO. STRATUS LOOKS TO LAST THROUGH THE
16-17Z TIME FRAME BEFORE LIFTING.
&&
.FIRE WEATHER...
ISSUED AT 344 PM MDT SUN SEP 15 2013
FIRE WEATHER CONCERNS WILL BE MINIMAL OVER THE CWA THROUGH NEXT
WEEKEND. THE WIDESPREAD AND SIGNIFICANT RAIN WILL BE COMING TO AN
END OVER THE CWA THIS EVENING...WITH SOME LATE DAY SHOWERS AND
THUNDERSTORMS OVER THE CWA MONDAY THROUGH WEDNESDAY. WARMER AND
DRIER CONDITIONS WILL EXIST OVER THE CWA THROUGH NEXT WEEKEND.
TEMPERATURES WILL RETURN TO NEAR OR ABOVE NORMAL AND MINIMUM
RELATIVE HUMIDITY VALUES WILL BE BETWEEN 25 AND 35 PERCENT OVER THE
LOWER ELEVATIONS. DAYTIME WINDS DO INCREASE OVER THE WEST PART OF
THE CWA MONDAY AND TUESDAY AS A SURFACE TROUGH FORMS ALONG THE
EASTERN WYOMING BORDER. THEN A COLD FRONT WILL MOVE ACROSS THE
CWA WEDNESDAY AFTERNOON AND EARLY EVENING. WINDS AHEAD OF AND
BEHIND THE FRONT WILL GUST AS HIGH AS 40 MPH THROUGH WEDNESDAY
NIGHT...ESPECIALLY IN AREAS ALONG AND WEST OF THE LARAMIE RANGE.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM...WEILAND
LONG TERM...RJM
AVIATION...CLAYCOMB
FIRE WEATHER...WEILAND
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
353 AM CDT WED SEP 18 2013
.DISCUSSION...
330 AM CDT
THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.
SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.
TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.
SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.
TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.
THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.
THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* SLIGHT CHANCE FOR A FEW ISOLATED SHOWERS THROUGH LATE MORNING.
* SOUTHERLY WINDS GUSTING TO ARND 20KT. STRONGEST GUSTS IN THE
LATE AFTERNOON.
KREIN
//DISCUSSION...UPDATED 06Z...
A WEAK SHORTWAVE MOVING ACROSS THE AREA TONIGHT COMBINED WITH
WARM AIR ADVECTION HAS GENERATED SOME ISOLATED SHOWERS TO DEVELOP.
HOWEVER...THE STRONGEST FOCUS WILL ALIGN FROM NERN IOWA INTO
CENTRAL WISCONSIN...SO THE GREATEST CHANCE FOR ANY SHRA TO IMPACT
ANY OF THE TERMINALS WILL BE AT RFD...THOUGH CANT RULE OUT A STRAY
SHOWER AS FAR EAST AS DPA. HOWEVER...IN GENERAL...CONFIDENCE IS
LOW THAT ANY PCPN WILL HAVE A SIGNIFICANT IMPACT ON ANY OF THE
TERMINALS. HAVE ADDED PROB30 GROUPS FOR NOW TO THE RFD/DPA TAFS.
THE MORE LIKELY SCENARIO WILL BE FOR LOWERING CLOUD BASES AS THE
WARM/MOIST ADVECTION SETS UP IN EARNEST OVER THE REGION...AND
BASED ON THE LATEST SATELLITE IMAGERY TRENDS AND MODEL RH
TIMESECTION FORECASTS...THERE IS A CHANCE THAT MVFR CIGS MAY SKIRT
THROUGH NCNTRL/NWRN IL...WITH RFD...AGAIN...THE MORE LIKELY
LOCATION TO SEE MVFR CIGS. EXPECT THAT THE TERMINALS TO THE EAST
WILL HAVE TOO MUCH DRIER AIR IN THE LOWEST LEVELS FOR BASES TO
LOWER TO MVFR.
AS A WEAK WARM FRONT LIFTS NORTH THROUGH NRN IL/IN DURG THE
MORNING HOURS...SELY WINDS WILL VEER SLY. THERE SHOULD BE ENOUGH
LOW LEVEL MIXING TO BRING SOME HIGHER GUSTS TO 15-18KT DOWN TO THE
SURFACE DURG THE LATE MORNING THROUGH EARLY EVENING.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* LOW CONFIDENCE IN SHRA DIRECTLY IMPACTING THE TERMINALS...AND
MEDIUM CONFIDENCE THAT THE TERMINALS WILL REMAIN DRY.
* MEDIUM CONFIDENCE IN CIG TRENDS.
* MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS.
KREIN
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
* THURSDAY...CHANCE OF TSRA IN THE AFTERNOON/EVENING. GUSTY
SOUTHWEST WINDS.
* FRIDAY...SHRA/TSRA LIKELY. MVFR POSSIBLE. WIND SHIFT TO THE
NORTHWEST IN THE AFTERNOON.
* SATURDAY THROUGH MONDAY...DRY/VFR. CMS
&&
.MARINE...
255 AM CDT
A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
333 AM CDT WED SEP 18 2013
.DISCUSSION...
330 AM CDT
THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.
SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.
TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.
SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.
TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.
THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.
THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* SLIGHT CHANCE FOR A FEW ISOLATED SHOWERS THROUGH LATE MORNING.
* GUSTY SOUTHERLY WINDS TO ARND 15-18KT.
KREIN
//DISCUSSION...UPDATED 06Z...
A WEAK SHORTWAVE MOVING ACROSS THE AREA TONIGHT COMBINED WITH
WARM AIR ADVECTION HAS GENERATED SOME ISOLATED SHOWERS TO DEVELOP.
HOWEVER...THE STRONGEST FOCUS WILL ALIGN FROM NERN IOWA INTO
CENTRAL WISCONSIN...SO THE GREATEST CHANCE FOR ANY SHRA TO IMPACT
ANY OF THE TERMINALS WILL BE AT RFD...THOUGH CANT RULE OUT A STRAY
SHOWER AS FAR EAST AS DPA. HOWEVER...IN GENERAL...CONFIDENCE IS
LOW THAT ANY PCPN WILL HAVE A SIGNIFICANT IMPACT ON ANY OF THE
TERMINALS. HAVE ADDED PROB30 GROUPS FOR NOW TO THE RFD/DPA TAFS.
THE MORE LIKELY SCENARIO WILL BE FOR LOWERING CLOUD BASES AS THE
WARM/MOIST ADVECTION SETS UP IN EARNEST OVER THE REGION...AND
BASED ON THE LATEST SATELLITE IMAGERY TRENDS AND MODEL RH
TIMESECTION FORECASTS...THERE IS A CHANCE THAT MVFR CIGS MAY SKIRT
THROUGH NCNTRL/NWRN IL...WITH RFD...AGAIN...THE MORE LIKELY
LOCATION TO SEE MVFR CIGS. EXPECT THAT THE TERMINALS TO THE EAST
WILL HAVE TOO MUCH DRIER AIR IN THE LOWEST LEVELS FOR BASES TO
LOWER TO MVFR.
AS A WEAK WARM FRONT LIFTS NORTH THROUGH NRN IL/IN DURG THE
MORNING HOURS...SELY WINDS WILL VEER SLY. THERE SHOULD BE ENOUGH
LOW LEVEL MIXING TO BRING SOME HIGHER GUSTS TO 15-18KT DOWN TO THE
SURFACE DURG THE LATE MORNING THROUGH EARLY EVENING.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* LOW CONFIDENCE IN SHRA DIRECTLY IMPACTING THE TERMINALS...AND
MEDIUM CONFIDENCE THAT THE TERMINALS WILL REMAIN DRY.
* MEDIUM CONFIDENCE IN CIG TRENDS.
* MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS.
KREIN
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
* THURSDAY...CHANCE OF TSRA IN THE AFTERNOON/EVENING. GUSTY
SOUTHWEST WINDS.
* FRIDAY...SHRA/TSRA LIKELY. MVFR POSSIBLE. WIND SHIFT TO THE
NORTHWEST IN THE AFTERNOON.
* SATURDAY THROUGH MONDAY...DRY/VFR. CMS
&&
.MARINE...
255 AM CDT
A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS JACKSON KY
127 AM EDT WED SEP 18 2013
.UPDATE...
ISSUED AT 126 AM EDT WED SEP 18 2013
THE FORECAST WAS PRETTY MUCH ON TRACK SO FAR TONIGHT. HOURLY
TEMPERATURES AND DEWPOINTS HAVE BEEN RUNNING PRETTY CLOSE TO THE
FORECAST VALUES. COVERAGE OF CLOUD COVER AND FOG HAS ALSO BEEN ON THE
MONEY COMPARED TO THE FORECAST. AS USUAL...OBSERVATIONAL DATA WAS
INGESTED INTO THE HOURLY GRIDS TO ESTABLISH SOME NEW TRENDS. ASIDE
FROM THAT...NO UPDATE TO THE FORECAST IS PLANNED AT THIS TIME.
UPDATE ISSUED AT 1055 PM EDT TUE SEP 17 2013
HAVE UPDATED THE FORECAST FOR THE NEAR TERM SKY/T/TD GRIDS BASED ON
CURRENT OBS AND TRENDS. THE 00Z NAM12 AND LATEST HRRR STILL KEEP MOST
OF THE SHOWERS WEST OF THE AREA THROUGH 12Z. UPDATES HAVE BEEN SENT
TO THE NDFD AND WEB SERVERS.
UPDATE ISSUED AT 745 PM EDT TUE SEP 17 2013
23Z SFC ANALYSIS SHOWS HIGH PRESSURE RETREATING OFF TO THE EAST IN
THE FACE OF APPROACHING LOW PRESSURE. THIS TRANSITION WILL BRING
LOWER CIGS TO EAST KENTUCKY TOWARD DAWN ALONG WITH A SMALL CHANCE OF
SHOWERS IN THE WESTERN PARTS OF THE AREA. THESE CLOUDS SHOULD LIMIT
THE FOG FORMATION TO THE DEEPER VALLEYS GENERALLY EAST OF JKL.
LIKEWISE...EXPECT A RIDGE TO VALLEY TEMPERATURE SPLIT OVER THE
EASTERN PARTS OF THE CWA WITH MILDER TEMPERATURES AND HIGHER
DEWPOINTS SEEN ELSEWHERE. HAVE UPDATED THE FORECAST GRIDS FOR THESE
THOUGHTS...ESSENTIALLY TWEAKING LOW TEMPS...ADJUSTING THE DIURNAL
CURVE...AND PULLING POPS WESTWARD THROUGH SUNRISE PER THE LATEST
NAM12 AND HRRR. THESE UPDATES HAVE BEEN SENT TO THE NDFD AND WEB
SERVERS...ALONG WITH A FRESHENED SET OF ZONES.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 250 PM EDT TUE SEP 17 2013
THE MODELS ARE IN PRETTY GOOD AGREEMENT. HIGH PRESSURE BUILD IN
BEHIND THE FRONT THAT MOVED THROUGH THE AREA YESTERDAY. THIS FRONT
WILL MOVE BACK TO THE NORTH AS A WARM FRONT THIS EVENING AND ALONG
WITH THE ISENTROPIC LIFT...WILL BE ABLE TO PRODUCE SOME ISOLATED TO
SCATTERED LIGHT RAIN SHOWERS LATE TONIGHT AND TOMORROW. THE FRONT AND
THE RAIN WILL CONTINUE TO MOVE TO THE NORTHEAST. THIS WILL ALLOW THE
TEMPS TO WARM UP AND FOR THE HUMIDITY TO INCREASE. FOR
TEMPERATURES...USED THE MODEL BLEND AND THE BUMPED THEM UP A COUPLE
OF DEGREES FOR THE HIGHS ON WEDNESDAY. THIS WAS A BIT OF A COMPROMISE
BETWEEN THE MOS AND THE RAW MODEL OUTPUT.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 250 PM EDT TUE SEP 17 2013
HIGH PRESSURE WILL BE FIRMLY IN CONTROL AT THE START OF THE PERIOD.
WHILE SOME MEAGER INSTABILITY WILL DEVELOP THURSDAY AND FRIDAY
AFTERNOONS...NOT MUCH OF A TRIGGER TO REALLY GET ANYTHING GOING. IN
FACT...INSTABILITY IS SO MEAGER...OPTING TO TREND POPS DOWNWARD BOTH
DAYS. NAM IS THE OUTLIER WITH A BIT MORE INSTABILITY...BUT ALSO
APPEARS TO BE BRINGING HIGHER DEWPOINTS IN MUCH TOO QUICK...SO HAVE
OPTED TO DISCOUNT THIS MODEL FOR THE TIME BEING.
MODELS CONTINUE THE TREND OF SLOWING DOWN THE COLD FRONT FOR THE
UPCOMING WEEKEND. IT NOW LOOKS LIKE THE FRONT SHOULD CROSS EASTERN
KENTUCKY FROM LATE FRIDAY NIGHT THROUGH SATURDAY. WILL CONTINUE THE
HIGH POPS DURING THIS PERIOD. HAVE TRENDED THE THUNDER POTENTIAL
DOWNWARD GIVEN THE LACK OF ANY SUBSTANTIAL INSTABILITY. SOME
ELEVATED THUNDER MAY BE POSSIBLE AT TIMES...BUT SURFACE INSTABILITY
NEVER GETS THAT STRONG...EVEN INTO SATURDAY AFTERNOON. FRONT MAY
LINGER ACROSS THE SOUTHEAST INTO SUNDAY MORNING BEFORE FINALLY
EXITING BY SUNDAY AFTERNOON...ALLOWING FOR DRY WEATHER TO END THE
WEEKEND. WITH HIGH PRESSURE BUILDING IN SUNDAY NIGHT...A QUIET START
TO THE NEW WEEK IS ANTICIPATED. HIGHS THURSDAY AND FRIDAY WILL
RETURN TO SLIGHTLY ABOVE NORMAL WITH PLENTY OF SUNSHINE...BUT WILL
TREND BACK BELOW NORMAL FOR THE WEEKEND INTO EARLY NEXT WEEK AS
COOLER WEATHER SETTLES IN BEHIND THE COLD FRONT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 126 AM EDT WED SEP 18 2013
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGHOUT THE TAF PERIOD.
VALLEY FOG SHOULD BE VERY MINIMAL TONIGHT...ASIDE FROM FAR EASTERN
PARTS OF THE AREA...DUE TO STEADILY INCREASING CLOUD COVER AND THE
FACT THAT WINDS WILL NOT LAY AS MUCH TONIGHT AS IN PREVIOUS NIGHTS.
LIGHT SHOWERS MAY MOVE INTO THE AREA TOWARD DAWN FROM THE WEST
GENERALLY CAUSING CIGS TO DROP DOWN TO AROUND 4K FT. HOWEVER...CIGS
AND VSBY ARE EXPECTED TO REMAIN VFR THROUGHOUT THE PERIOD. HAVE
INCLUDED VCSH FOR THE DAYTIME HOURS. WINDS WILL BE LIGHT AND VARIABLE
THROUGHOUT THE FORECAST.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AR
SHORT TERM...JJ
LONG TERM...KAS
AVIATION...AR
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
124 AM EDT WED SEP 18 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 421 PM EDT TUE SEP 17 2013
17Z WV IMAGERY AND RUC ANALYSIS INDICATED A WELL-DEFINED SHORTWAVE
LIFTING NE THROUGH ERN IA. DPVA...7H FGEN AND 305K ISENTROPIC ASCENT
ASSOC WITH THE SHORTWAVE HAS SUPPORTED AN AREA OF SHOWERS OVER
NORTHEAST IA. VIS SATELLITE HAS SHOWN AN EXPANSION OF DIURNAL CU
FROM MNM-DELTA-ALGER COUNTIES EASTWARD IN AN AREA OF HIGHER
DEWPOINTS (UPPER 40 TO LOWER 50S) AIDED BY SOUTHERLY FLOW OFF LAKE
MI AND BAY OF GREEN BAY. RDGG ALOFT AND AT THE SFC HAS KEPT THE REST
OF THE FCST AREA GENERALLY CLOUD FREE THIS AFTERNOON.
TONIGHT...MDLS SUGGEST THAT AS THE IA SHRTWV GRADUALLY LIFTS TO THE
NORTHEAST...MOISTURE WILL INCREASE AND BRING SOME LIGHT WAA PCPN
INTO THE AREA AS 300K-310K ISENTROPIC ASCENT SPREADS FROM SE MN AND
WRN WI TOWARD UPPER MI. THE NAM/GFS ARE STILL A BIT MORE AGGRESSIVE
IN BRINGING SOME LIGHT PCPN INTO THE CWA COMPARED TO THE GEM/ECMWF.
GIVEN THE VERY DRY ANTECEDENT AIRMASS...THE NAM/GFS MAY BE TOO QUICK
SO USED MORE OF A MODEL BLEND FOR POPS WITH ONLY A 30 PCT CHC OF
LIGHT SHOWERS TOWARD 12Z NEAR THE WI BORDER WITH SLIGHT CHC ACROSS
MUCH OF THE REST OF THE WEST HALF.
WEDNESDAY...GIVEN PREDICTED TRACK OF ERN IA SHORTWAVE EXPECT BEST
FORCING FOR SHRA TO BE MAINLY CENTRAL COUNTIES IN THE MORNING AND
THEN TO SPREAD INTO THE EASTERN COUNTIES IN THE AFTERNOON. HAVE ONLY
SLIGHT CHC POPS FOR SHRA WEST AWAY FROM BETTER FORCING ASSOC WITH
SHORTWAVE. MODEL MLCAPES OTHER THAN NAM SHOW ONLY MARGINAL
INSTABILITY OF A FEW HUNDRED J/KG AT BEST OVER THE AREA SO WILL ONLY
INCLUDED SLIGHT CHC MENTION OF TS IN THE GRIDS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 421 PM EDT TUE SEP 17 2013
LITTLE CHANGES TO THE LARGE SCALE PATTERN FOR THE LONG TERM PERIOD
OVER THE LAST 24 HOURS. AREA WILL BE UNDER WEAK UPPER RIDGING TO
START THE PERIOD...WHICH WILL LEAD TO BROAD WARM AIR ADVECTION AND
THE POTENTIAL FOR SOME SHOWERS/THUNDERSTORMS WEDNESDAY NIGHT INTO
THURSDAY AS A WARM FRONT LIFTS ACROSS THE AREA. BEST CHANCES ON
WEDNESDAY NIGHT WILL BE EARLY ON WHEN THE STRONGEST WARM AIR
ADVECTION MOVES THROUGH AND BEFORE THE DEEPER MOISTURE STARTS TO
CUTOUT. THIS BROAD WAA WILL ALSO LEAD TO TEMPERATURES RISING TO
ABOVE NORMAL VALUES FOR WEDNESDAY NIGHT AND THURSDAY...WITH LOWS IN
THE UPPER 50S AND LOWER 60S AND HIGHS IN THE 70S TO LOWER 80S.
FINALLY FOR WEDNESDAY NIGHT...SINCE THE MODELS CONTINUE TO SHOW THE
POTENTIAL FOR LOW CLOUDS AND FOG...DID UP THE FOG TO AREAS FOR SOME
LOCATIONS IN FAVORED UPSLOPE HIGHER TERRAIN.
PRECIPITATION CHANCES WILL INCREASE HEADING INTO LATE THURSDAY
AFTERNOON AND THURSDAY NIGHT...AS THE UPPER TROUGH PUSHES NORTHEAST
THROUGH THE UPPER GREAT LAKES AND ONTARIO. AN ASSOCIATED LOW
PRESSURE SYSTEM WILL MOVE THROUGH NORTHWEST ONTARIO...BUT IT WILL
PUSH A COLD FRONT EAST ACROSS THE CWA THURSDAY NIGHT INTO FRIDAY
MORNING. ECMWF IS STILL SHOWING THE SLOWEST FRONTAL PASSAGE...WITH
THE PRECIPITATION LINGERING INTO EARLY FRIDAY AFTERNOON AS ANOTHER
WAVE RIDES UP THE FRONT. THERE CONTINUES TO BE SOME MINOR TIMING
DIFFERENCES IN THE COLD FRONT PASSAGE AND SHOWERS...BUT THE GENERAL
IDEA IS SIMILAR WITH MOST LOCATIONS LIKELY TO SEE 0.25-0.5IN OF
RAIN. AS FOR THUNDER...THERE ARE DECENT VARIATIONS IN THE
INSTABILITY...WITH SOME MODELS EVEN SHOWING UP TO 3000 J/KG OF ML
CAPE IF THERE IS ENOUGH CLEARING/HEATING IN THE AFTERNOON. 0-6KM AND
EFFECTIVE SHEAR VALUES STILL LOOK TO BE ON THE MARGINAL SIDE
(25-30KTS) ON THURSDAY AFTERNOON AND THEN INCREASE RIGHT ALONG THE
FRONTAL BOUNDARY. WOULD THINK THE BEST OPPORTUNITY FOR STRONGER
THUNDERSTORMS WOULD BE RIGHT ALONG THE FRONT AS IT MOVES INTO THE
WESTERN CWA LATE THURSDAY AFTERNOON INTO THE EVENING. AT THIS
POINT...THINK BRIEF HEAVY RAIN AND MARGINALLY SEVERE HAIL WOULD BE
THE BIGGEST THREATS IF THE UPDRAFTS CAN BE SUSTAINED.
DRIER AND COOLER AIR WILL MOVE IN RIGHT BEHIND THE FRONT AND SHOULD
LEAD TO A PERIOD OF DRY WEATHER AND EVEN SOME CLEARING FOR A FEW
HOURS. BUT MUCH COLDER AIR...WILL START TO SURGE IN WITH MORE
LOW LEVEL MOISTURE LATER FRIDAY AFTERNOON AND CONTINUE INTO THE
FIRST PART OF SATURDAY. WITH THE FLOW BEING MORE
WEST-NORTHWEST...EXPECT THE MOST CLOUDS TO BE OVER THE NORTH HALF
OF THE CWA AND WITH THE COLDER AIR THERE...EVEN SOME LAKE ENHANCED
CLOUDS (DELTA-T VALUES BETWEEN 10-14) IN THOSE WIND FAVORED AREAS.
WITH THE LATEST TRENDS OF CLOUD DEPTHS BEING 3-4KFT...SHOULD BE
ENOUGH FOR ISOLATED/SCATTERED SHOWERS AND MAY NEED TO ADJUST POPS A
LITTLE HIGHER OVER THE COMING SHIFTS.
THE UPPER TROUGH WILL LIFT NORTHEAST ON SATURDAY NIGHT AND ALLOW
UPPER RIDGING AND HIGH PRESSURE TO BUILD INTO THE AREA FOR SUNDAY.
THUS...EXPECT A DRY SECOND HALF OF THE WEEKEND...ALTHOUGH
TEMPERATURES WON/T WARM UP TOO SIGNIFICANTLY (WITH HIGHS AROUND 60).
ALSO...SATURDAY NIGHT COULD SEE SOME FROST OVER THE INTERIOR WEST
WHERE SKIES BEGIN TO CLEAR AND WINDS LET UP DUE TO THE APPROACHING
HIGH.
THIS HIGH WILL QUICKLY SHIFT EAST-NORTHEAST INTO QUEBEC ON
MONDAY...AS THE AREA IS UNDER THE UPPER RIDGE AXIS. STILL EXPECT
MONDAY TO BE DRY AND MUCH WARMER (HIGHS IN THE MID-UPPER 60S)...BUT
THE NEXT UPPER TROUGH IS LURKING TO THE WEST. THIS UPPER TROUGH
LOOKS TO GIVE A GLANCING BLOW TO THE CWA ON MONDAY NIGHT INTO
TUESDAY AND WILL HIGHLIGHT THE BEST POPS OVER THE NORTHWESTERN HALF
OF THE CWA.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 124 AM EDT WED SEP 18 2013
EXPECT LLWS AT ALL 3 TAF SITES INTO THIS MRNG WITH NOCTURNAL COOLING
CAUSING A RADIATION INVERSION AND DECOUPLING OF A LIGHTER SFC FLOW
FM THE STRONGER SSW WINDS ABOVE THE INVERSION. THIS INCRSGLY MOIST
SSW WIND WL BRING MVFR/IFR CIGS INTO UPR MI BY SUNRISE. BEST CHC FOR
THE IFR CONDITIONS WL BE AT IWD THIS MRNG DOWNWIND OF THE LOWER CIGS
OBSVD UPSTREAM. ALTHOUGH THERE MAY BE SOME DIURNAL RECOVERY IN CIG
HGT THIS AFTN...PERSISTENCE OF LLVL MSTR UNDER LO INVRN THRU THIS
EVNG IN ADVANCE OF APRCHG WARM FNT WARRANTS A MENTION OF CONTINUED
MVFR CIGS.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 421 PM EDT TUE SEP 17 2013
BETWEEN HIGH TO THE EAST AND LOW PRES OVER THE PLAINS...SRLY WINDS
WILL REMAIN UP TO 20 KNOTS INTO WED. WINDS SHOULD THEN REMAIN BELOW
20 KNOTS UNTIL LATE THU NIGHT AND FRI WHEN A COLD FRONT MOVES
THROUGH THE REGION AND BRINGS W TO NW WINDS UP TO 30 KNOTS FRI INTO
SAT. WINDS WILL DECREASE BLO 20 KT BY SUNDAY AS HIGH PRESSURE BUILDS
IN FM THE WEST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...SRF
AVIATION...KC
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
328 AM CDT WED SEP 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT WED SEP 18 2013
AN AREA OF LOW PRESSURE WAS LOCATED OVER THE WESTERN DAKOTAS...WITH
HIGH PRESSURE ACROSS THE EASTERN SEABOARD. THIS SETUP RESULTED IN
SOUTHERLY FLOW ACROSS THE UPPER MIDWEST WAS BRINGING WARM MOIST AIR
TO THE REGION. THIS WAA WAS EASILY IDENTIFIED BY LOOKING AT THE H850
TEMPERATURE ADVECTION OFF THE SPC MESOANALYSIS PAGE. THE LOW LEVEL
MOISTURE WAS EVIDENT BY THE STRATUS DECK THAT COVERED THE ENTIRE
UPPER MISSISSIPPI RIVER VALLEY WITH POCKETS OF DRIZZLE AND FOG. A
FEW AREAS OF ELEVATED CONVECTION MANAGED TO DEVELOP ALONG THE
EAST/WEST MUCAPE GRADIENT. SINCE THESE STORMS WERE ELEVATED...THEY
WERE UNABLE TO TAKE ADVANTAGE OF THE 0-1KM SHEAR AND HELICITY OF
30KTS AND 300M2/S2 RESPECTIVELY...AND DRIFTED HARMLESSLY EAST
NORTHEAST WITH THE MEAN WIND.
MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING HOW THE STATUS FIELD
WILL EVOLVE TODAY. H850 TEMPS WILL INCREASE FROM AROUND 12-15C EARLY
THIS MORNING...TO 20-22C THIS AFTERNOON. THAT WARM LAYER ALOFT WILL
ONLY ENHANCE THE CAPPING INVERSION AND LIMIT MIXING THIS AFTERNOON.
AS A RESULT IT MAY BE DIFFICULT TO LOOSE THE CLOUDS...WHICH IN TURN
WILL HAMPER TODAYS HIGH TEMPERATURES. MOST LIKELY IT WILL EITHER BE
BOOM OR BUST WITH HIGHS TODAY. THE NAM AND HRRR CLEAR OUT THE
CLOUDS BY EARLY THIS AFTERNOON WHICH WOULD FAVOR A WARMER SOLUTION.
HOWEVER...JUST WITHIN THE INDIVIDUAL MEMBERS OF THE SREF THE HIGH
TEMPERATURE TODAY VARIES FROM 89 TO 77 AT KMSP. MEMBER 2 OF THE
HOPWRF KEEPS THE CLOUDS ACROSS THE CWA THROUGH 21Z THIS
AFTERNOON...SO HAVE TRENDED BACK TEMPERATURES SLIGHTLY TO REFLECT
THE MORE CLOUDY SCENARIO. AS THE WARM FRONT LIFT NORTHWARD THIS
AFTERNOON AND OVERNIGHT PRECIP CHANCES WILL DECREASE FROM SOUTH TO
NORTH...BUT RETURN AGAIN EARLY THURSDAY MORNING AS THE COLD FRONT
APPROACHES FROM THE WEST.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 328 AM CDT WED SEP 18 2013
SHOWERS AND SOME THUNDERSTORMS WILL LIKELY BE ONGOING ACROSS THE
FAR EASTERN DAKOTAS AND WESTERN MINNESOTA THURSDAY MORNING. MOIST
SOUTHERLY FLOW WITH PW VALUES OF 1.5 TO 1.8 INCHES...ROUGHLY 220
PERCENT OF NORMAL...AND 850 MB TEMPS OF +20C WILL OVERSPREAD THE
REGION. THE CAPPING INVERSION PRODUCED BY THIS ABUNDANCE OF WARM
AIR ALOFT WILL LIKELY CONTRIBUTE TO CONSIDERABLE CLOUDINESS
THROUGH MUCH OF THE DAY WITH LITTLE HOPE OF DEEP MIXING AND
ERODING THE CAP SUFFICIENTLY AHEAD OF THE FRONT. THIS WILL PROVE
DETRIMENTAL ON WIDESPREAD CONVECTIVE CHANCES TO SOME
DEGREE...UNLESS SURFACE TEMPS DO WARM INTO THE 80S. BEST POTENTIAL
FOR THIS WOULD BE ACROSS WESTERN WI AS FROPA WILL TAKE PLACE LATE
IN THE DAY. MID LEVEL LAPSE RATES WILL CONTRIBUTE TO AROUND 2000
J/KG MLCAPE...SO IF THE CAP DOES ERODE...WIDESPREAD THUNDERSTORMS
CAN BE EXPECTED. MODEST SPEED SHEAR WOULD ALSO HELP ORGANIZE A FEW
STORMS ENOUGH FOR A MARGINAL SEVERE THREAT.
COOLER AND DRIER AIR WILL FOLLOW THURSDAY NIGHT INTO SATURDAY. AS
THE HIGH PUSHES OVERHEAD FRIDAY NIGHT...TEMPERATURES COULD FALL
INTO THE 30S IN SOME LOCATIONS IF WINDS DECOUPLE.
RETURN FLOW WILL COMMENCE SATURDAY NIGHT AND STRENGTHEN INTO EARLY
NEXT WEEK AS TROUGHING DIGS INTO THE PACIFIC NORTHWEST. SOUTHWEST
FLOW WILL KEEP THE STORM TRACK WEST OF THE REGION...AND COLD
FRONTS/DISTURBANCES PUSHING THROUGH WILL NOT HAVE MUCH PUNCH. ONE
SUCH FRONT IS PROGGED FOR MONDAY AND MONDAY NIGHT...WITH THE ECMWF
THE STRONGEST OF ALL GUIDANCE. ONLY LOW POPS WERE JUSTIFIED.
TEMPERATURES WILL BE ABOVE AVERAGE EARLY NEXT WEEK...AND 80S MAY
RETURN FOR MIDWEEK WITH 925 MB TEMPS CLIMBING INTO THE 20S C.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1040 PM CDT TUE SEP 17 2013
LIFR CIGS AND IFR VSBYS CONTINUE TO SPREAD NORTH INTO CENTRAL MN
LATE THIS EVENING. THE MN TAF SITES WILL EXPERIENCE CIGS AT OR
BELOW 005 FOR THE OVERNIGHT THROUGH MID MORNING HOURS ON WED.
VSBYS WILL BE 1-3SM IN -DZ/-RA/BR. THESE CONDITIONS WILL SPREAD
INTO KRNH AND KEAU...IT WILL JUST TAKE A LITTLE LONGER. THERE
REMAINS THE THREAT OF THUNDER... PRIMARILY FROM KMSP ON EAST AND
SOUTH OVERNIGHT AS THE LOW LEVEL JET/MOISTURE TRANSPORT/
INSTABILITY GRADIENT MOVE THROUGH IN THE 08Z-13Z TIME FRAME. VCTS
REMAIN IN FOR KMSP... KRNH AND KEAU. TIMING ON LIFTING THE CEILINGS
AND VSBYS BACK TO VFR REMAINS ABOUT THE SAME FROM THE PREVIOUS TAF
PACKAGE WITH CLEARING MOVING FROM KRWF LATE IN THE MORNING TO KEAU
BY LATE IN THE AFTERNOON. SE WINDS NEAR 10 KNOTS THROUGH MUCH OF
THE PERIOD. THE WINDS WILL BE A LITTLE STRONGER (15G22KTS) FOR KRWF
AND KAXN WEDNESDAY AFTERNOON ALONG WITH MORE OF A SOUTHERLY
DIRECTION (170).
KMSP...CEILINGS CONTINUING A DOWNWARD TREND OVERNIGHT REACHING
004-005 BY WED MORNING. -RA/-DZ AT THE START OF THE TAF WILL GIVE
WAY TO SOME SHOWERS OVERNIGHT AND EARLY WED MORNING. A THUNDERSTORM
REMAINS POSSIBLE IN THE 08Z-11Z TIME FRAME. CEILINGS SHOULD BE
SLOW TO LIFT WEDNESDAY MORNING WITH A BREAKOUT TO VFR STILL
EXPECTED BY 21Z.
/OUTLOOK FOR KMSP/
THU...MVFR CIGS WITH SHRA/TSRA. WINDS S 10 KTS BCMG W IN THE AFTN.
FRI...VFR. WINDS NW 15G25 KTS.
SAT...VFR. WINDS NW 5-10 KT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...JRB
LONG TERM...BORGHOFF
AVIATION...RAH
AREA FORECAST DISCUSSION
NWS DULUTH MN
1255 AM CDT WED SEP 18 2013
.UPDATE...
ISSUED AT 1253 AM CDT WED SEP 18 2013
UPDATED FOR AVIATION DISCUSSION
UPDATE ISSUED AT 645 PM CDT TUE SEP 17 2013
HAVE UPDATED SKY CONDITIONS FOR A MORE OVERCAST OVERNIGHT
FORECAST...AND A DELAY IN CLEARING FOR WEDNESDAY MORNING.
OTHERWISE LITTLE/NO CHANGE TO CURRENT FORECAST.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 318 PM CDT TUE SEP 17 2013
MOISTURE CONTINUED TO INCREASE FROM WEST TO EAST ACROSS THE
NORTHLAND TODAY. THE HIGH TO THE EAST WAS LOSING IT`S GRIP ON THE
NORTHLAND. A SHORTWAVE WAS MOVING NORTHEAST OUT OF IOWA AND WILL
COMBINE WITH WAA/MOISTURE ADVECTION TO CAUSE CLOUDS TO THICKEN ALL
AREAS TONIGHT AND BRING A CHANCE FOR RAIN. THE RAP WAS DOING A
GOOD JOB DEPICTING THE CLOUDS OVER OUR WESTERN CWA AND THEY SHOW
INCREASING HUMIDITY ACROSS MUCH OF THE AREA BY 06Z. RAIN WILL BE
POSSIBLE TONIGHT...AND WE INCREASED POPS OVER OUR FAR SOUTHERN CWA
WHICH WILL HAVE THE BEST CHANCE AT SEEING UP TO A TENTH OF AN INCH
OVERNIGHT. PWAT VALUES ARE EXPECTED TO RISE TO 1 TO 1.4 INCHES
OVERNIGHT...AND WE EXPECT AREAS OF FOG TO FORM. MOST AREAS SHOULD
NOT EXPERIENCE DENSE FOG...WITH THE EXCEPTION OF AREAS AROUND LAKE
SUPERIOR LATE TONIGHT WHICH COULD SEE SOME PATCHY DENSE FOG. SURFACE
DEWPOINTS ARE EXPECTED TO RISE INTO THE FIFTIES...AND WERE ALREADY
50 TO 55 FROM KINL TO KGPZ TO KAIT AND POINTS WEST. WE KEPT THE
MENTION OF DRIZZLE TONIGHT FOR MOST AREAS...ALTHOUGH WE DON`T
THINK IT WILL BE WIDESPREAD GIVEN UPSTREAM CONDITIONS. AREAS
AROUND THE LAKE WILL HAVE A BETTER CHANCE AND IT COULD BE
WIDESPREAD LATE TONIGHT INTO WEDNESDAY MORNING.
STABILITY GRADUALLY LOWERS TONIGHT...AND WE ADDED A SLIGHT CHANCE
FOR A THUNDERSTORM ACROSS THE SOUTH LATE. WAA WILL CONTINUE
WEDNESDAY...WITH A SHORTWAVE RIDGE ALOFT MOVING THROUGH EARLY.
WE HAVE A CHANCE FOR MORE SHOWERS/STORMS OVER ALL BUT FAR
NORTHWEST AREAS ON WEDNESDAY...WITH THE BEST CHANCE OCCURRING
EARLY. CLOUDS WILL SLOWLY DIMINISH OVER WESTERN AREAS...BUT
SHOULD REMAIN THROUGH MOST OF THE DAY AROUND LAKE SUPERIOR AND
OVER NORTHWEST WISCONSIN. HIGHS WILL RANGE FROM THE MID SIXTIES TO
MID SEVENTIES ACROSS THE NORTHLAND...WARMEST SOUTHWEST...COOLEST
AROUND LAKE SUPERIOR.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 318 PM CDT TUE SEP 17 2013
THE FIRST FEW DAYS OF THIS PERIOD WILL BE STORMY AND WET THEN BECOME
CHILLY WITH A STRONG COLD FRONTAL PASSAGE.
STRONG WAA THAT WILL BE ONGOING AHEAD OF AN APPROACHING COLD FRONT
WILL CONTINUE CLOUDS WEDNESDAY NIGHT. KEPT IN CHANCE OF SHOWERS
AND THUNDERSTORMS WEDNESDAY NIGHT...BUT VERY WARM MID LEVEL TEMPS
MAY PROHIBIT STORM FORMATION. BOTH THE NAM AND GFS SHOW SURGE OF 7H
10+C TEMPS. MUCH BETTER CHANCE OF THUNDERSTORMS WILL BE THURSDAY AS
A STRONG COLD FRONT APPROACHES THE AREA FROM THE WEST. THE NAM MAY BE
A BIT FASTER...BUT THE MODELS ARE IN PRETTY GOOD AGREEMENT WITH
MOVEMENT OF THE FRONT AND RESULTING QPF. DURING THE DAY THE
ATMOSPHERE DESTABILIZES IN THE STRONG WAA REGIME AND WILL BE PRIMED
FOR STORMS WHEN THE FRONT ARRIVES IN THE AFTERNOON/EARLY EVENING
EVENING. LIL`S FORECAST DOWN TO -6 AND MUCAPES UP TO 2500 J/KG. AN
EXTRA BOOST OF LIFT WILL BE PROVIDED BY AN UPPER LEVEL JET AND
S/WV.
STRONG COLD AIR WILL STREAM INTO THE REGION BEHIND THE FRONT FOR THE
FRIDAY...BUT AS HIGH PRESSURE BUILDS INTO THE REGION THE WEEKEND
WILL HAVE SUNSHINE BUT COOLER TEMPS. THIS WILL BE FOLLOWED BY
ANOTHER LOW PRESSURE/COLD FRONT ON FROM EARLY THROUGH MID WEEK WITH
A STRONG UPPER LEVEL TROF/CLOSED LOW.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1253 AM CDT WED SEP 18 2013
CONDITIONS TO GRADUALLY DETERIORATE OVER THE NEXT FEW HOURS...WITH
CIGS AND VSBYS FALLING INTO IFR...POSSIBLY LIFR FOR SEVERAL HOURS
DURING THE EARLY MORNING HOURS GENERALLY BETWEEN 09Z AND 15Z.
CONDITIONS TO BE BETTER FARTHER NORTH...WITH ONLY MVFR CONDITIONS
EXPECTED. SOUTHERN SITES MOST LIKELY TO DROP TO LIFR WITH -RA OR
-DZ AND FOG WITH VISBYS TO LIFR AT TIMES AS WELL. CIGS LIKELY TO
LINGER THIS MORNING...WITH CLEARING NOT EXPECTED UNTIL THIS
AFTERNOON. THIS AFTERNOON IF SOME HOLES CAN DEVELOP IN THE OVERCAST
WE MAY BE ABLE TO DEVELOP SOME SHOWERS WITH ISOLATED THUNDER DURING
THE LATE MORNING AND AFTERNOON...BUT CONFIDENCE IS NOT HIGH AND FOR
NOW HAVE ONLY PUT IN VCSH. SOME CLEARING SHOULD OCCUR BY LATE
AFTERNOON...ONLY TO FILL IN AGAIN DURING THE EVENING AS THE COLD
FRONT MOVES INTO THE AREA FROM THE WEST.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 62 74 51 61 / 50 70 30 20
INL 60 71 49 56 / 50 60 30 30
BRD 65 74 49 63 / 50 60 10 10
HYR 62 76 49 64 / 40 70 30 10
ASX 59 78 51 63 / 40 70 40 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
UPDATE...DAP/LE
SHORT TERM...MELDE
LONG TERM...CLC
AVIATION...LE
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
355 AM CDT WED SEP 18 2013
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013
CHALLENGES INCLUDE CLOUD COVER AND TEMPERATURES THROUGH THE DAY
AND THEN CONVECTIVE CHANCES AND SEVERE POTENTIAL THIS EVENING
THROUGH THURSDAY. DESPITE DIFFERING QPF AMOUNTS AND LOCATIONS...
GFS/NAM/ECMWF ARE IN GOOD OVERALL AGREEMENT WITH SURFACE LOW TRACK.
THE GEM IS AN OUTLIER AND WILL NOT BE CONSIDERED WITH THIS FORECAST.
FOCUSED ON THE RAP FOR NEAR TERM CLOUD/TEMPERATURE TRENDS.
LOW CLOUDS HAVE ONCE AGAIN ENVELOPED THE ENTIRE FORECAST AREA AND
EXPECT A VERY SLOW EROSION FROM SOUTHWEST TO NORTHEAST THROUGH THE
DAY DUE TO MOIST SOUTH-SOUTHEAST FLOW AND A STRONG MID-LEVEL
INVERSION. RAP 925 HPA RH SUGGESTS THE SUN SHOULD BEGIN TO MAKE AN
APPEARANCE ACROSS SOUTHEAST ND INTO THE DEVILS LAKE BASIN BY EARLY
AFTERNOON...BUT MUCH OF NORTHEAST ND INTO NORTHWEST MN WILL REMAIN
CLOUDY THROUGH THE DAY. WITH INCREASED CLOUD COVER...DROPPED
HIGH TEMPERATURES 3 TO 5 DEGREES. THIS MAY STILL NOT BE ENOUGH
NOTING YESTERDAY/S SLOW RECOVERY. AS A RESULT...SOME AREAS ACROSS
THE NORTH MAY NOT TOP 70 DEGREES. OTHERWISE...HIGHS WILL RANGE
FROM THE LOW 70S ACROSS THE NORTH TO THE LOW 80S ACROSS THE SOUTH.
ADDED SOME SLIGHT CHANCE POPS TO THE DEVILS LAKE BASIN THIS MORNING
TO ACCOUNT FOR WEAKENING ECHOES CURRENTLY ACROSS THE WESTERN HALF
OF ND. OTHERWISE...MOST OF THE DAY SHOULD BE DRY GIVEN A STRONG
CAP AND DELAYED DYNAMIC SUPPORT. REMOVED POPS THROUGH 21 UTC...
INCREASING TO HIGH CHANCES FROM WEST TO EAST THEREAFTER.
SURFACE LOW WILL TRACK ALONG THE ND/SD BORDER WITH A WARM FRONT
EXTENDING TO THE EAST AND INTO WEST CENTRAL MN. CLEARING SKIES
LATE THIS AFTERNOON WILL HELP REALIZE 2000 TO 3000 J/KG OF
INSTABILITY AND WITH PWATS INCREASING TO 1.5 INCHES AND THE
APPROACHING WARM FRONT...EXPECT SCATTERED CONVECTIVE DEVELOPMENT
INITIALLY ACROSS THE SOUTHERN FORECAST AREA. SHOWERS AND
THUNDERSTORMS SHOULD EXPAND NORTHWARD THROUGH THE EVENING WITH THE
APPROACHING COLD FRONT AND STRONG FORCING ALOFT. SPC DAY ONE
CONVECTIVE OUTLOOK HAS EXPANDED ITS SLIGHT RISK TO INCLUDE ALMOST
ALL OF EASTERN ND AND PORTIONS OF NORTHWEST MN. SOME STORMS MAY
BECOME STRONG TO SEVERE WITH THE PRIMARY THREATS BEING LARGE HAIL
AND DAMAGING WIND...BUT CANNOT RULE OUT A TORNADO OR TWO...
ESPECIALLY NEAR FRONTAL BOUNDARIES.
THUNDERSTORMS THAT DEVELOP WILL MOVE EASTWARD AHEAD OF THE ADVANCING
COLD FRONT AND SHOULD EXIT THE FORECAST AREA BY NOON ON THURSDAY.
BREEZY NORTHWEST WIND WILL FOLLOW FRONTAL PASSAGE WITH COOLING
TEMPERATURES. HIGHS THURSDAY WILL RANGE FROM THE LOWER 60S ACROSS
THE NORTHWEST TO THE LOWER 70S ACROSS THE SOUTHEAST.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013
WITH THE EXCEPTION OF SOME LINGERING WRAP-AROUND SHOWERS ACROSS
THE LAKE OF THE WOODS REGION...FRIDAY WILL BE PARTLY SUNNY AND DRY
AS SURFACE HIGH PRESSURE BUILDS ACROSS THE NATION/S MID-SECTION.
BREEZY NORTHWEST WIND WILL PERSIST AND TEMPERATURES WILL TOP OUT
IN THE LOWER TO MID 60S REGION-WIDE.
SATURDAY-TUESDAY...00Z MODELS APPEAR STABLE RUN TO RUN AND CONFIDENCE
IS SLIGHTLY BETTER THAN AVERAGE. PERIOD BEGINS WITH RIDGING ALOFT...
WITH SOUTHWEST FLOW DEVELOPING BY THE END OF THE WEEKEND. THE
STRONGEST SIGNAL FOR PRECIP APPEARS TO BE MONDAY-MONDAY NIGHT.
SOUTHWEST FLOW ALOFT CONTINUES INTO TUESDAY...ALTHOUGH THERE IS NO
CLEAR SIGNAL FOR PRECIP. TEMPERATURES WILL BEGIN NEAR NORMAL...AND
TRANSITION TO SLIGHTLY ABOVE NORMAL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1115 PM CDT TUE SEP 17 2013
THE BAND OF MVFR/IFR CIGS AND SOME FOG/DRIZZLE CONTINUES TO
PERSIST ALONG AND EAST OF THE RED RIVER VALLEY. CONDITIONS SHOULD
FALL INTO THE IFR CATEGORY FOR ALL BUT THE FAR WEST TONIGHT INTO
WED MORNING. GFK COULD BE ON THE EDGE OF THE CLOUD BAND FOR A TIME
TONIGHT...BEFORE CLOUDS ADVECT TO THE WEST WED MORNING. MODELS
WANT TO CLEAR THINGS OUT QUICKLY WED MORNING...BUT THIS IS LIKELY
A BIT TOO QUICK AND SOMETHING WE WILL HAVE TO MONITOR FOR TIMING
PURPOSES. WINDS SHOULD GUST BETWEEN 25-30KT BY WED AFTERNOON IN
ALL AREAS WITH INCREASING CHANCES FOR SHOWERS/STORMS IN THE WEST
AND NORTH AROUND 00Z THU...AND HAVE MENTIONED SOME VCTS FOR
THREAT.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
SHORT TERM...ROGERS
LONG TERM...ROGERS/TG
AVIATION...DK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1241 AM CDT WED SEP 18 2013
.UPDATE...
ISSUED AT 1232 AM CDT WED SEP 18 2013
CONVECTION MOVING THROUGH WESTERN NORTH DAKOTA HAS POSED A PROBLEM
OVER THE PAST FEW HOURS. SEVERAL WIND MEASUREMENTS FROM 60 MPH TO AS
HIGH AS 83 MPH WERE TAKEN WITHIN 40 MILES OF THE MONTANA-NORTH
DAKOTA BORDER. IT APPEARED THAT SEVERE CRITERIA WIND GUSTS STAYED
JUST ACROSS THE BORDER...THOUGH...AS NO OBSERVATION SITES ON THE
BORDER OR IN NORTH DAKOTA EXCEEDED 40 KNOTS. PRECIPITATION CHANCES
WERE ALTERED OVER THE NEXT 8 HOURS TO ACCOUNT FOR THE LATEST RADAR
TRENDS.
UPDATE ISSUED AT 948 PM CDT TUE SEP 17 2013
A LINE OF NON-SEVERE THUNDERSTORMS HAVE DEVELOPED OVER
SOUTHEASTERN MONTANA COINCIDENT WITH A SHORTWAVE ALOFT AND A
SURFACE BOUNDARY. THE LATEST HRRR IS A LOT MORE BROAD WITH THIS
CONVECTION THAN THE RADAR TRENDS SUGGEST. BASED ON RADAR
OBS/TRENDS...ADDED MORE TEMPORAL AND SPATIAL RESOLUTION TO THE
FORECAST BY INCREASING POPS TO NUMEROUS ACROSS THE SOUTHWEST FOR
THE NEXT FEW HOURS.
THERE IS STILL SOME UNCERTAINTY IF THIS LINE WILL HOLD TOGETHER
AFTER MIDNIGHT OR BREAK UP AS IT MOVES INTO AN AREA OF HIGHER
CONVECTIVE INHIBITION OVER WESTERN NORTH DAKOTA. FOR NOW KEPT
CHANCE POPS WEST AFTER MIDNIGHT AS SHORT-RANGE MODEL GUIDANCE
PAINTS SOME LINGERING CONVECTION OVER THE WESTERN CWA AFTER
MIDNIGHT. THE UPDATED PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 658 PM CDT TUE SEP 17 2013
A STRONG THUNDERSTORM HAS DEVELOPED ALONG A SURFACE BOUNDARY NEAR
THE ND/MT BORDER SOUTH OF SATHER DAM. THIS AREA IS CHARACTERIZED BY
SURFACE-BASED CAPE AROUND 1600 J/KG AND 0-6KM SHEAR AROUND 30
KNOTS. GIVEN THE MARGINAL SEVERE ENVIRONMENT...THINK ANY STORMS
THAT DEVELOP WITHIN THE NEXT HOUR OR TWO SHOULD REMAIN BELOW
SEVERE LIMITS. HOWEVER...WOULD NOT BE SURPRISED TO GET SOME NICKEL
HAIL REPORTS WITH THE STRONGEST CELLS. WILL CONTINUE TO MONITOR
RADAR AND ADJUST THE FORECAST ACCORDINGLY. THE UPDATED PRODUCTS
HAVE BEEN SENT.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 325 PM CDT TUE SEP 17 2013
THE MAIN FORECAST ISSUE IN THE SHORT TERM PERIOD IS CONVECTIVE
TRENDS/COVERAGE/INTENSITY TONIGHT AND WEDNESDAY. IN THE NEAR
TERM...LOWS CLOUDS HAVE ERODED SLIGHTLY ACROSS THE JAMES RIVER
VALLEY BUT ARE HANGING IN THERE. THERE MAY BE SOME PARTIAL
CLEARING DURING THE EARLY EVENING...BUT STRATUS IS AGAIN EXPECTED
TO FILL BACK IN OVERNIGHT. IN GENERAL...HAVE FAVORED THE SLOWER
MODEL SOLUTIONS FOR POPS TONIGHT...ALTHOUGH I DID ADD A SLIGHT
CHANCE IN THE EXTREME NORTHWEST BEGINNING AT 00Z TONIGHT AS A FEW
SHOWERS HAVE DEVELOPED IN NORTHEAST MONTANA. AM EXPECTING HIGHEST
COVERAGE OF STORMS OVERNIGHT TO BE IN THE NORTHWEST...AND REMAIN
BELOW SEVERE LIMITS. ON WEDNESDAY...A SURFACE LOW AND ASSOCIATED
COLD FRONT WILL PUSH THROUGH THE STATE. STRONG WARM AIR ADVECTION
AHEAD OF THE FRONT WILL PROVIDE SIGNIFICANT WARM AIR ALOFT...WHICH
SHOULD HELP SUPPRESS STORMS OVER MUCH OF THE FORECAST AREA. PER
THE SPC SWODY2 DISCUSSION...THERE IS A CONDITIONAL THREAT OF
SEVERE WEATHER...MAINLY NORTH...IF THE CAP IS BROKEN. THAT THREAT
WOULD ALSO INCLUDE AN ISOLATED TORNADO DUE IN PART TO BACKED SURFACE
FLOW NEAR THE SURFACE LOW. DID NOT CHANGE PREVIOUS FORECAST MUCH
AT ALL IN TERMS OF POPS...WITH CHANCE TO LIKELY ACROSS THE NORTH.
THERE WILL LIKELY BE A RATHER LARGE TEMPERATURE SPREAD FROM
NORTHWEST TO SOUTHEAST ACROSS THE FORECAST AREA ON
WEDNESDAY...WITH HIGHS IN THE LOWER 70S NORTHWEST TO MID/UPPER 80S
SOUTHEAST.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 325 PM CDT TUE SEP 17 2013
FOCUS IN THE LONG TERM IS ON THE POTENTIAL FOR SEVERE WEATHER
WEDNESDAY NIGHT.
THE 12 UTC GUIDANCE SUITE IS IN GOOD AGREEMENT ON A SURFACE LOW
ACROSS SOUTHEAST MONTANA WEDNESDAY MORNING PROPAGATING INTO CENTRAL
NORTH DAKOTA BY LATE AFTERNOON. AN ASSOCIATED COLD FRONT IS FORECAST
TO BE NEAR THE HIGHWAY 83 CORRIDOR BY 00 UTC THURSDAY. WIDESPREAD
HIGHS IN THE 80S ARE FORECAST AHEAD OF THE COLD FRONT WITH SURFACE
DEWPOINTS IN THE 60S. DECENT DEEP LAYER BULK SHEAR AND SURFACE BASED
CAPE VALUES OF 1500-2000 J/KG AHEAD OF THE FRONT WITH THE AMPLE
MOISTURE AND DAYTIME HEATING WILL GIVE THE POTENTIAL FOR SUPERCELL
FORMATION. HOWEVER...THE 12 UTC NAM/GFS BUFR SOUNDINGS INDICATE
CAPPING IN THE 850 TO 800 MB LEVEL...WHICH WILL PLACE A LIMIT ON
SURFACE INITIATION IF FRONTAL FORCING CANNOT OVERCOME THIS
INHIBITION. THE BEST CHANCE FOR CONVECTION IS EXPECTED TO BE
WEDNESDAY EVENING AND INTO THE NIGHT NORTH OF HIGHWAY 2. SPC DOES
HAVE A SLIGHT RISK ACROSS THE NORTHWEST AND NORTH CENTRAL WEDNESDAY.
MAIN THREATS WILL BE LARGE HAIL AND DAMAGING WINDS...BUT WITH DECENT
LOW LEVEL SHEAR THE TORNADO THREAT CAN NOT BE RULED OUT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1232 AM CDT WED SEP 18 2013
THUNDERSTORMS ARE FORECAST AT ALL TAF SITES IN THE NEXT 24
HOURS...BUT KBIS/KMOT/KJMS TIMING IS NOT WELL KNOWN AT THIS POINT.
VCTS IS INDICATED AT THOSE SITES. KISN/KDIK HAVE THUNDERSTORMS
ONGOING...SO TIMING IS ESTIMATED IN CURRENT TAF. FRONTAL PASSAGE
TOMORROW WILL RESULT IN WIND SHIFT FROM SOUTHERLY TO
WESTERLY...AND COULD GUST UP TO 30 KNOTS FOR A FEW HOURS AFTER
THE WIND SHIFT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SCHECK
SHORT TERM...RK
LONG TERM...MM
AVIATION...SCHECK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
948 PM CDT TUE SEP 17 2013
.UPDATE...
ISSUED AT 948 PM CDT TUE SEP 17 2013
A LINE OF NON-SEVERE THUNDERSTORMS HAVE DEVELOPED OVER
SOUTHEASTERN MONTANA COINCIDENT WITH A SHORTWAVE ALOFT AND A
SURFACE BOUNDARY. THE LATEST HRRR IS A LOT MORE BROAD WITH THIS
CONVECTION THAN THE RADAR TRENDS SUGGEST. BASED ON RADAR
OBS/TRENDS...ADDED MORE TEMPORAL AND SPATIAL RESOLUTION TO THE
FORECAST BY INCREASING POPS TO NUMEROUS ACROSS THE SOUTHWEST FOR
THE NEXT FEW HOURS.
THERE IS STILL SOME UNCERTAINTY IF THIS LINE WILL HOLD TOGETHER
AFTER MIDNIGHT OR BREAK UP AS IT MOVES INTO AN AREA OF HIGHER
CONVECTIVE INHIBITION OVER WESTERN NORTH DAKOTA. FOR NOW KEPT
CHANCE POPS WEST AFTER MIDNIGHT AS SHORT-RANGE MODEL GUIDANCE
PAINTS SOME LINGERING CONVECTION OVER THE WESTERN CWA AFTER
MIDNIGHT. THE UPDATED PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 658 PM CDT TUE SEP 17 2013
A STRONG THUNDERSTORM HAS DEVELOPED ALONG A SURFACE BOUNDARY NEAR
THE ND/MT BORDER SOUTH OF SATHER DAM. THIS AREA IS CHARACTERIZED BY
SURFACE-BASED CAPE AROUND 1600 J/KG AND 0-6KM SHEAR AROUND 30
KNOTS. GIVEN THE MARGINAL SEVERE ENVIRONMENT...THINK ANY STORMS
THAT DEVELOP WITHIN THE NEXT HOUR OR TWO SHOULD REMAIN BELOW
SEVERE LIMITS. HOWEVER...WOULD NOT BE SURPRISED TO GET SOME NICKEL
HAIL REPORTS WITH THE STRONGEST CELLS. WILL CONTINUE TO MONITOR
RADAR AND ADJUST THE FORECAST ACCORDINGLY. THE UPDATED PRODUCTS
HAVE BEEN SENT.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 325 PM CDT TUE SEP 17 2013
THE MAIN FORECAST ISSUE IN THE SHORT TERM PERIOD IS CONVECTIVE
TRENDS/COVERAGE/INTENSITY TONIGHT AND WEDNESDAY. IN THE NEAR
TERM...LOWS CLOUDS HAVE ERODED SLIGHTLY ACROSS THE JAMES RIVER
VALLEY BUT ARE HANGING IN THERE. THERE MAY BE SOME PARTIAL
CLEARING DURING THE EARLY EVENING...BUT STRATUS IS AGAIN EXPECTED
TO FILL BACK IN OVERNIGHT. IN GENERAL...HAVE FAVORED THE SLOWER
MODEL SOLUTIONS FOR POPS TONIGHT...ALTHOUGH I DID ADD A SLIGHT
CHANCE IN THE EXTREME NORTHWEST BEGINNING AT 00Z TONIGHT AS A FEW
SHOWERS HAVE DEVELOPED IN NORTHEAST MONTANA. AM EXPECTING HIGHEST
COVERAGE OF STORMS OVERNIGHT TO BE IN THE NORTHWEST...AND REMAIN
BELOW SEVERE LIMITS. ON WEDNESDAY...A SURFACE LOW AND ASSOCIATED
COLD FRONT WILL PUSH THROUGH THE STATE. STRONG WARM AIR ADVECTION
AHEAD OF THE FRONT WILL PROVIDE SIGNIFICANT WARM AIR ALOFT...WHICH
SHOULD HELP SUPPRESS STORMS OVER MUCH OF THE FORECAST AREA. PER
THE SPC SWODY2 DISCUSSION...THERE IS A CONDITIONAL THREAT OF
SEVERE WEATHER...MAINLY NORTH...IF THE CAP IS BROKEN. THAT THREAT
WOULD ALSO INCLUDE AN ISOLATED TORNADO DUE IN PART TO BACKED SURFACE
FLOW NEAR THE SURFACE LOW. DID NOT CHANGE PREVIOUS FORECAST MUCH
AT ALL IN TERMS OF POPS...WITH CHANCE TO LIKELY ACROSS THE NORTH.
THERE WILL LIKELY BE A RATHER LARGE TEMPERATURE SPREAD FROM
NORTHWEST TO SOUTHEAST ACROSS THE FORECAST AREA ON
WEDNESDAY...WITH HIGHS IN THE LOWER 70S NORTHWEST TO MID/UPPER 80S
SOUTHEAST.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 325 PM CDT TUE SEP 17 2013
FOCUS IN THE LONG TERM IS ON THE POTENTIAL FOR SEVERE WEATHER
WEDNESDAY NIGHT.
THE 12 UTC GUIDANCE SUITE IS IN GOOD AGREEMENT ON A SURFACE LOW
ACROSS SOUTHEAST MONTANA WEDNESDAY MORNING PROPAGATING INTO CENTRAL
NORTH DAKOTA BY LATE AFTERNOON. AN ASSOCIATED COLD FRONT IS FORECAST
TO BE NEAR THE HIGHWAY 83 CORRIDOR BY 00 UTC THURSDAY. WIDESPREAD
HIGHS IN THE 80S ARE FORECAST AHEAD OF THE COLD FRONT WITH SURFACE
DEWPOINTS IN THE 60S. DECENT DEEP LAYER BULK SHEAR AND SURFACE BASED
CAPE VALUES OF 1500-2000 J/KG AHEAD OF THE FRONT WITH THE AMPLE
MOISTURE AND DAYTIME HEATING WILL GIVE THE POTENTIAL FOR SUPERCELL
FORMATION. HOWEVER...THE 12 UTC NAM/GFS BUFR SOUNDINGS INDICATE
CAPPING IN THE 850 TO 800 MB LEVEL...WHICH WILL PLACE A LIMIT ON
SURFACE INITIATION IF FRONTAL FORCING CANNOT OVERCOME THIS
INHIBITION. THE BEST CHANCE FOR CONVECTION IS EXPECTED TO BE
WEDNESDAY EVENING AND INTO THE NIGHT NORTH OF HIGHWAY 2. SPC DOES
HAVE A SLIGHT RISK ACROSS THE NORTHWEST AND NORTH CENTRAL WEDNESDAY.
MAIN THREATS WILL BE LARGE HAIL AND DAMAGING WINDS...BUT WITH DECENT
LOW LEVEL SHEAR THE TORNADO THREAT CAN NOT BE RULED OUT.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 658 PM CDT TUE SEP 17 2013
MVFR CIGS WILL CONTINUE OVER KJMS THROUGH THE OVERNIGHT HOURS.
OTHERWISE...VFR CONDITIONS ARE EXPECTED TO PREVAIL ALONG AND WEST
OF HIGHWAY 83 TONIGHT. FURTHERMORE...THUNDERSTORMS COULD DEVELOP
OVER KISN-KDIK TONIGHT. GIVEN THE UNCERTAINTY REGARDING ACTUAL
TIMING AND LOCATION OF THUNDERSTORMS...INDICATED VCTS IN THE KISN-
KDIK TAFS. AS A COLD FRONT PUSHES INTO CENTRAL NORTH DAKOTA
WEDNESDAY...THUNDERSTORMS COULD DEVELOP FROM KBIS-KMOT AFTER 21Z.
THE FRONT WILL ALSO SCOUR OUT THE MVFR CIGS OVER KJMS BY WEDNESDAY
AFTERNOON.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...RK
LONG TERM...MM
AVIATION...TM
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1250 AM CDT WED SEP 18 2013
.UPDATE...
ISSUED AT 924 PM CDT TUE SEP 17 2013
INCREASED THE COVERAGE OF DRIZZLE AND FOG AS STRONG THETA E
ADVECTION AROUND 925MB AND 850MB NOT PROVIDING THE AREA WITH MUCH
IN THE WAY OF SHOWER DEVELOPMENT. LATEST RAP AND NAM SOUNDINGS
SUGGEST A BIT MORE OF A CAP WHEN LIFTING A PARCEL FROM ABOUT 850MB
SO THE THREAT FOR THUNDERSTORMS IS FAIRLY LOW AS WELL...ALTHOUGH
THE GOING 20 TO 30 POPS ALREADY PRETTY LOW. DID PICK UP SOME
MEASURABLE DRIZZLE AT THE AIRPORT. THE BACK EDGE OF THE STRATUS
DOES APPEAR TO FINALLY BE SLOWING AS A DECK AROUND 1500 FEET
LOOKS TO BE DEVELOPING AND STREAMING NORTHWEST. THE VISIBILITIES
HAVE BEEN GRADUALLY IMPROVING SO AT THIS TIME NOT CONCERNED ABOUT
A DENSE FOG ADVISORY. AS ALWAYS ONE AREA TO WATCH WILL BE THE
WESTERN EDGE BETWEEN THE STRATUS AND CLEAR SKIES. THE STRONGEST
LLJ/THETA E ADVECTION WILL END AROUND 6Z SO THE POTENTIAL FOR THE
DRIZZLE TO DECREASE AFTER 6Z AND NOT BE NEARLY AS WIDESPREAD EARLY
WEDNESDAY MORNING.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 354 PM CDT TUE SEP 17 2013
THE MAIN FORECAST CHALLENGE TONIGHT IS NOT SO MUCH PRECIPITATION
CHANCES BUT MORE SO WITH CLOUD COVER. CURRENT SATELLITE DEPICTS THE
EDGE OF THE CLEARING JUST WEST OF CHAMBERLAIN AND GREGORY COUNTY.
THE NAM SOUNDINGS AND HUMIDITY TIME SECTIONS ARE TOO BULLISH AT THIS
TIME WITH THE CLEARING SO WERE NOT FOLLOWED FOR THE TONIGHT AND
EARLY WEDNESDAY TIME FRAME. WHAT LOOKED CLOSER WAS THE RAP13 AND
GFS40 SOUNDINGS AND SUBSEQUENT LOW LEVEL HUMIDITY FIELDS. THEY SHOW
A CLEARING TREND MOVING NORTHEASTWARD THROUGH OUR SOUTHWEST ZONES
TONIGHT...WITH CLOUD COVER PINWHEELING BACK TOWARD THE WEST IN OUR
EAST CENTRAL SD ZONES SUCH AS HURON. THIS IS HOW THE CLOUD FORECAST
WAS PLAYED...WITH CLEARING SKIES EDGING TOWARD YANKTON AS THE NIGHT
PROGRESSES...BUT LEAVING HURON CONSIDERABLY CLOUDY. THE MOISTURE
TONIGHT AND EARLY WEDNESDAY DOES BECOME MORE AND MORE SHALLOW. SO BY
WEDNESDAY...IT IS CONCEIVABLE THAT THE CLOUD COVER COULD EXIT OR MIX
OUT IN A BIG HURRY...WITH THE POSSIBLE EXCEPTION OF SOME LINGERING
STRATUS OR STRATOCU IN OUR FAR EASTERN ZONES UNTIL MIDDAY WEDNESDAY.
WITH OR WITHOUT CLOUDS...LOWS WILL BE IMPACTED MORE BY WARM MOIST
ADVECTION TONIGHT AND SOUTHERLY WINDS. THEREFORE MANY LOCATIONS WILL
NOT DROP OFF HARDLY AT ALL FROM THEIR CURRENT TEMPERATURES. AND MANY
LOCATIONS IN OUR EASTERN ZONES MAY EVEN WARM UP A TAD INTO MID
EVENING. TEMPERATURES ON WEDNESDAY STILL LOOK TO BE WELL ABOVE
NORMAL AHEAD OF THE ADVANCING COLD FRONT. CONCERNING RAIN
POTENTIAL...LOOKS TO BE SLIM OR NONE ON WEDNESDAY. BUT LINGERED A
FEW LIGHT SHOWERS ACROSS OUR EASTERN ZONES TONIGHT WHERE THE DEEPEST
LAYER MOISTURE RESIDES. THERE COULD BE SOME PATCHY FOG THROUGHOUT
PARTS OF OUR EASTERN ZONES LATE TONIGHT ALSO.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 354 PM CDT TUE SEP 17 2013
JET ENERGY HANGING BACK QUITE A BIT GOING INTO THE EVENING BACK
THROUGH THE ROCKIES...BUT APPEARS TO MAKE PROGRESS EASTWARD
THROUGH THE NIGHT AS TROUGH NUDGES UP AGAINST PLAINS RIDGE. PROSPECT
FOR CONVECTION FAIRLY MINIMAL WITH STRONGLY CAPPED ATMOSPHERE
AHEAD OF THE BOUNDARY...WHICH REALLY DOES NOT MAKE ITS APPROACH TO
THE CWA UNTIL TOWARD 06Z. MOST...IF NOT ALL...DEEP LAYER FORCING
FOR LIFT IS POST FRONTAL...WITH WITH ELEVATED CAPE ON THE ORDER OF
500-750 J/KG...SO SHOULD BE ABLE TO SCRAPE UP AN INCREASING POTENTIAL
FOR CONVECTION BY LATE NIGHT AND EARLY MORNING FOR POSTFRONTAL AREAS.
FOR ALL THE FAULTS...THE CANADIAN GLOBAL MAY ACTUALLY HAVE THE
CORRECTLY SLANTED VIEW OF THE PRECIP DISTRIBUTION...DEVELOPING
PRECIP A BIT SLOWER...AND A BIT MORE WESTWARD REMOVED FROM LOW
LEVEL FRONTAL POSITION BY VERY LATE WED NIGHT AND THURSDAY.
FOCUS FOR CONVECTION WILL GRADUALLY SHIFT SOUTHEAST WITH THE
PROGRESSION OF DIV Q/FRONTOGENETIC FORCING...WITH MAX FORCING
COMING TOGETHER PERHAPS EARLY MORNING IN THE NORTH/NORTHEAST...
AND AGAIN WITH MAIN JET ENTRANCE DRAGGING ACROSS IN THE AFTERNOON
FOR THE SOUTHEAST. AVERAGE OF A QUARTER TO THIRD INCH IS NOT HARD
TO SUPPORT...EVEN WITH THE DRIER LAYER BELOW CLOUD BASE. TEMPS
WILL BE SOMEWHAT DIFFICULT TO RECOVER MUCH WITH ABUNDANCE OF
CLOUDS... AND UNDERCUTTING COLD AIR ADVECTION DURING THE DAY.
WARMEST MAY SANDWICH THE AREA...BOTH NORTHWEST WHERE WILL GET SOME
SUNSHINE LATER IN THE DAY AND BETTER MIXING...AND THE FAR
SOUTHEAST WHERE SURFACE BOUNDARY WILL LINGER THROUGH THE EARLY
MORNING WITH A FAIRLY MILD START.
FRIDAY INTO SATURDAY WILL FEATURE A COOLER AIRMASS WORKING
SOUTHWARD INTO THE PLAINS...AND WILL BE BREEZY AS WELL WITH MIXING
SUGGESTING DEWPOINTS WELL DOWN INTO THE 30S. THIS WILL OPEN THE
DOOR ON WHAT LOOKS LIKE A CLASSIC RADIATIVE COOLING NIGHT ON
FRIDAY NIGHT...AND SHOULD AT LEAST GET CLOSE TO HAVING SOME UPPER
30S IN COLDER LOCATIONS ALONG/EAST OF INTERSTATE 29. SUPPORT IN
SOME OF THE ENSEMBLE MOS GUIDANCE
RIDGE REBUILDING ACROSS THE PLAINS THIS WEEKEND...AND AS COOL HIGH
SHIFTS EAST WILL GET MODERATING SOUTHERLY WIND FLOW DEVELOPING.
PROBABLY WILL NOT GET FULL IMPACT OF WARMING WINDS YET ON SATURDAY
FOR EASTERN AREAS WITH FAIRLY WEAK FLOW...BUT WEST WILL RESPOND
NICELY RETURNING BACK ABOVE NORMAL. INCREASING WINDS SATURDAY
NIGHT INTO SUNDAY...AS TROUGH IN THE ROCKIES MOVES EAST WITH
PRESSURE FALLS IN LEE ACROSS WESTERN PLAINS. MIXING WILL START TO
BE SOMEWHAT MORE CHALLENGED WITH STABILIZING PROFILES AND SOUTH TO
SOUTHEAST COMPONENT. ANOTHER FAIRLY SHORT WAVELENGTH TROUGH
EXPECTED TO PUSH ACROSS THE NORTHERN PLAINS IN THE SUNDAY NIGHT TO
MONDAY WINDOW...SOME UNCERTAINTY IN TIMING. HOWEVER...SHORT
WAVELENGTH DOES PRODUCE DECENT DYNAMIC FORCING FOR LIFT...AND
WHILE MOISTURE WILL BE SOMEWHAT CHALLENGED TO RETURN...HAVE KEPT
UP WITH GENERALLY MID TO HIGHER CHANCE POPS AS FRONTAL BOUNDARY
PUSHES ACROSS THE AREA. QUICKLY DRYING BEHIND...AND TEMPS
REMAINING MILD FOR TUESDAY WITH MEAN RIDGE BECOMING REESTABLISHED.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 1245 AM CDT WED SEP 18 2013
WIDE RANGE OF FLIGHT CATEGORIES OUT THERE TONIGHT...RANGING FROM
LIFR IN PORTIONS OF SOUTHWEST MINNESOTA AND NORTHWEST IOWA TO VFR IN
SOUTH CENTRAL SOUTH DAKOTA. CONTINUES TO BE A TOUGH CALL ON THE
EVOLUTION OF STRATUS AND FOG OVERNIGHT. CLEARING CONTINUES TO MAKE
SOME PROGRESS TO THE NORTHEAST...HOWEVER SIGNS OF NEW STRATUS
DEVELOPING RIGHT BEHIND THE CLEARING. SO THINKING IS MOST AREAS THAT
ARE IN THE STRATUS WILL GENERALLY REMAIN THAT WAY THROUGH THE NIGHT.
TOUGH TO FIGURE OUT WHAT CIGS WILL BE...THUS FEEL THE BEST FORECAST
AT THIS TIME WILL BE TAKING INTO ACCOUNT PERSISTENCE AND ADVECTION.
MODELS SUGGEST THAT THE FAVORED AREA TO SEE A CONTINUED LOWERING OF
THE CIGS AND VISIBILITIES WILL NORTH OF INTERSTATE 90. THUS
CONFIDENCE IS A LITTLE GREATER THAT KHON WILL DROP TO LIFR LATER
TONIGHT. AT KFSD...MOST SITES UPSTREAM ARE IFR...THUS WILL STAY WITH
PERSISTENCE AND NOT DROP TO LIFR IN THIS TAF ISSUANCE. ALTHOUGH IT
IS CERTAINLY POSSIBLE THAT CIGS DO TANK LATER TONIGHT...SO WILL HAVE
TO CONTINUE TO MONITOR. AT KSUX...CLEARING IS NOT TOO FAR AWAY...BUT
NEW STRATUS APPEARS TO BE FORMING. IT IS UNCLEAR AT WHICH HEIGHT
THIS NEW STRATUS WILL SETTLE IN AT. FOR NOW WILL KEEP LOW END
MVFR...BUT AGAIN WILL HAVE TO FOLLOW TRENDS. GIVEN THE SHALLOW
MOISTURE LAYER...WOULD EXPECT TO SEE THE STRATUS DISSIPATE FROM
SOUTHWEST TO NORTHEAST MID TO LATE MORNING. SOME SIGNS THAT IT MAY
EVOLVE INTO STRATOCU FOR THE AFTERNOON HOURS. FOR NOW WILL CARRY A
SCATTERED GROUP AT OUR EASTERN TAF SITES...BUT IT IS POSSIBLE THIS
STRATOCU EXTENDS THE MVFR TIME INTO THE AFTERNOON AT KFSD AND KSUX.
OTHERWISE...IT WILL BE A BREEZY DAY...WITH SOUTHERLY GUSTS UP TO 25
KTS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...08
SHORT TERM...MJ
LONG TERM...CHAPMAN
AVIATION...CHENARD
AREA FORECAST DISCUSSION...UPDATED
NWS SPOKANE WA
1042 PM PDT Tue Sep 17 2013
.SYNOPSIS...
A vigorous upper level disturbance will bring showers and
thunderstorms to north Idaho and the eastern third of Washington
tonight. Rain amounts of a half inch to an inch will be possible
over the Palouse into the Sliver Valley. Rain showers will linger
over the Idaho Panhandle on Wednesday. A drying and warming trend
will occur on Thursday and Friday. A slow moving cold front will
bring increasing chances for rain and cooler weather for the
weekend.
&&
.DISCUSSION...
Two areas of concern this evening. First area stretched from the
southeast corner of WA northeast towards Sandpoint. This area of
rain is mainly stratiform with an occiasonal lightning strike here
or there. Rainfall amounts have ranged from 0.15 to 0.30 with a
localized 0.50 at Corral Creek near the ID/WA/OR border. This band
of rain will keep pushing northeast through the night. The second
area of concern is across northern WA...mainly the Okanogan Valley
and Okanogan Highlands and northeast corner of WA. This has been a
bit more convective in nature. The storms are very slow moving and
radar has indicated rainfall amounts of an inch or more at several
locations. Have issued an Areal Flood Adisory for an area of
heavier rain from Nespelem to Keller to Miles. The precipitation is
very slow moving and the heavy rain could lead to localized
flooding on small creeks and streams as well as along
roadways...like Highway 21. The HRRR models shows this area of
showers slowly shifting east through the night and into Wednesday
morning across northeast WA and north ID. /Nisbet
&&
.AVIATION...
06Z TAFS: Widespread rain continues for most of eastern WA and north
ID. The 06z TAFs may be a bit optimistic with ending time of -shra
for KGEG and KSFF as radar is filling in from the west. If the cloud
cover can hang around through the night and early morning hrs as
well as elevated winds we may be able to aviod stratus/fog across
the eastern TAF locations.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 50 62 46 75 50 79 / 100 50 10 0 0 0
Coeur d`Alene 49 60 44 73 48 78 / 100 80 10 0 0 0
Pullman 48 63 41 77 46 81 / 100 30 10 0 0 0
Lewiston 53 68 49 83 53 87 / 100 20 10 0 0 0
Colville 50 65 43 75 45 79 / 100 60 20 0 0 10
Sandpoint 50 57 37 71 42 76 / 100 100 20 0 0 0
Kellogg 49 55 44 72 49 78 / 100 90 30 10 0 0
Moses Lake 51 73 46 79 50 80 / 10 0 0 0 0 10
Wenatchee 52 72 51 77 57 78 / 20 10 0 0 10 10
Omak 51 73 47 76 50 77 / 80 10 10 0 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1133 PM CDT TUE SEP 17 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 315 PM CDT TUE SEP 17 2013
THE MAIN FOCUS IS ON PRECIPITATION CHANCES TONIGHT AND HOW LONG
THEY WILL HOLD ON INTO WEDNESDAY.
LIGHT RAIN SHOWERS CONTINUE TO TRACK TO THE NORTHEAST ACROSS THE
AREA ALONG A SHARP MID LEVEL TROUGH AND WEAKENING MCV. RAINFALL
AMOUNTS HAVE BEEN LIGHT WITH THIS FEATURE AT LESS THAN A TENTH OF
AN INCH AND GUIDANCE HAS NOT DONE A VERY GOOD JOB OF PICKING UP ON
IT. THE EXCEPTION IS THE HRRR WHICH HAS HELD IT TOGETHER THROUGH
MUCH OF TODAY AND CONTINUES TO TAKE IT NORTHEAST INTO NORTH
CENTRAL WISCONSIN THIS EVENING.
WITH BROAD MID LEVEL TROUGHING REMAINING IN PLACE ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY TONIGHT AND LOW LEVEL MOISTURE TRANSPORT
INCREASING OUT OF THE CENTRAL PLAINS...EXPECT THAT SHOWERS AND A
SOME THUNDERSTORMS WILL DEVELOP AND INCREASE IN COVERAGE THROUGH THE
NIGHT. GUIDANCE HAS BEEN FAIRLY CONSISTENT WITH THE NOSE OF THIS
TRANSPORT BEING FOCUSED ACROSS SOUTHEAST MINNESOTA AND NORTHEAST
IOWA...WHICH IS ALSO WHERE THE HIGHEST INSTABILITY DEVELOPS AS
WELL. WIND SHEAR REMAINS LOW OVERNIGHT WITH INSTABILITY ALSO
STAYING ON THE LOW SIDE AND PEAKING AT ABOUT 500-1000J/KG IN
MN/IA. THUS...AM NOT EXPECTING ANY ORGANIZED CONVECTION TO OCCUR.
AS THE TROUGH SHIFTS EAST WITH UPPER LEVEL RIDGING COMING IN TOMORROW
MORNING AND THE MOISTURE TRANSPORT WEAKENS...EXPECT THAT THE
CONVECTION WILL EITHER SHIFT EAST OR DIMINISH IN COVERAGE ALLOWING
FOR A PRECIPITATION FREE DAY. IT WILL BE MUCH MORE HUMID WITH
SURFACE DEW POINTS CLIMBING INTO THE MID TO UPPER 60S. HIGH
TEMPERATURES WILL DEPEND GREATLY UPON CLOUD COVER AS THE STRATUS
IS EXPECTED TO LINGER FOR MUCH OF THE DAY. IF IT CLEARS EARLIER
THAN FORECAST...THEN TEMPS COULD BE ABOUT 4-8F HIGHER.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 315 PM CDT TUE SEP 17 2013
WITH UPPER LEVEL RIDGING IN PLACE WEDNESDAY NIGHT...HAVE GONE DRY
FOR MUCH OF THE REGION DESPITE SOME LOW LEVEL MOISTURE TRANSPORT
DEVELOPING AGAIN. THE MAIN FOCUS FOR PRECIPITATION WILL BE ALONG
THE COLD FRONT AS IT TRACKS TO THE EAST ON THURSDAY OUT AHEAD OF A
CLOSED MID LEVEL LOW. THE 17.12Z NAM CONTINUES TO BE THE FASTEST
OF THE MODEL SOLUTIONS FOR THIS FRONTAL PASSAGE AND HAS IT INTO
CENTRAL WISCONSIN BY 00Z FRIDAY WHILE THE 17.12Z GFS/ECMWF HOLD IT
BACK WEST OF THE MISSISSIPPI RIVER AT THAT SAME POINT. THE TIMING
OF THIS COLD FRONT PASSAGE WILL BE THE MAIN FACTOR WITH WHERE ANY
POTENTIAL SEVERE WEATHER COULD OCCUR. WHILE DEEP SHEAR LOOKS
WEAK...MODIFIED 17.12Z NAM/GFS SOUNDINGS WITH SURFACE DEW POINTS
IN THE UPPER 60S...RATHER THAN LOW/MID 70S...SHOW ABOUT
2000-3000J/KG OF MIXED LAYER CAPE DEVELOPING AHEAD OF THE FRONT.
IF THERE IS ANY SHEAR...ITS IN THE LOWEST 2-3KM AT ABOUT 20-30KTS
WHICH COULD HELP WITH POTENTIALLY ORGANIZING SOME OF THE
CONVECTION INTO BOWING SEGMENTS BRIEFLY.
AS THE FRONT MOVES THROUGH...PRECIPITATION IS EXPECTED TO END
OVERNIGHT INTO FRIDAY MORNING...THOUGH THE 17.12Z ECMWF HAS
DEVIATED FROM THAT WITH DEVELOPING A STRONGER SECONDARY MID LEVEL
TROUGH. THIS WOULD RUN THE PRECIPITATION LONGER AND HEAVIER THAN
WHAT WE ARE CURRENTLY FORECASTING...BUT HAVE SLOWED DOWN THE
EASTWARD PROGRESSION OF THE PRECIPITATION CHANCES A TAD.
BEYOND THAT...UPPER LEVEL RIDGING SETS UP FOR THE WEEKEND ON INTO
EARLY NEXT WEEK WITH THE REGION STAYING UNDER A COOL AIR MASS
BEFORE THE FLOW BECOMES MORE SOUTHWESTERLY TOWARD MID WEEK. WITH
LITTLE TO NO INSTABILITY AROUND FOR THE NEXT SYSTEM THAT APPEARS
TO COME IN ON MONDAY NIGHT...HAVE REMOVED THE THUNDER MENTION FOR
THAT PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1133 PM CDT TUE SEP 17 2013
AS MEAN UPPER TROUGH CONTINUES TO PUSH INTO INTERMOUNTAIN WEST
RESPONSE IS BROAD AREA OF LIFT AND WARM AIR ADVECTION ACROSS
NORTHERN MIDWEST AND WESTERN GREAT LAKES. SATURATION HAS LED TO
LOWER CEILINGS AND VISIBILITIES OVER PARTS OF MINNESOTA AND IOWA
WHERE LIFR AND IFR CONDITIONS BEING OBSERVED. AHEAD OF THIS
ZONE...NORTH AND EAST OF THE BEST UPGLIDE...CEILINGS STAYING UP AT
MOMENT.
NOT TOO MUCH CHANGE IS EXPECTED OVERNIGHT WITH WORST CONDITIONS WEST
OF THE MISSISSIPPI RIVER...WHICH COULD WORSEN A BIT OVERNIGHT. IN
ADDITION LOW LEVEL JET AND ASSOCIATED MOISTURE TRANSPORT WILL
CONTINUE TO DEVELOP SCATTERED SHOWERS WHICH COULD LAST WELL THROUGH
WEDNESDAY MORNING.
LIFT SUBSIDES FOR A BIT LATER WEDNESDAY WITH SHORT TERM RIDGING.
THIS COULD ACTUALLY BRING IN SLIGHTLY DRIER AIR FROM THE WEST AND
ALLOW STRATUS TO BREAK UP FROM WEST TO EAST. BUFKIT SOUNDS CERTAINLY
HINT AT THIS POTENTIAL SO WILL TRY AND REMAIN OPTIMISTIC WITH
CONDITIONS RETURNING TO VFR AREA WIDE BY 00Z THURSDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...SHEA
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1059 AM CDT WED SEP 18 2013
.DISCUSSION...UPDATE FOR THIS AFTERNOON..
1057 AM CDT
MAIN SHORT TERM CONCERN IS POTENTIAL FOR EAST CENTRAL IA
THUNDERSTORMS REACHING THE WESTERN AND FAR NORTHER EASTERN
PORTIONS OF THE FORECAST AREA LATE THIS MORNING THROUGH THE FIRST
PART OF THE AFTERNOON. OTHER CONCERNS SKY COVER AND TEMPERATURE
TRENDS/MAX TEMPS.
TRSA THAT DEVELOPED OVER WESTERN IA LATE LAST NIGHT HAD BEEN
MOVING STEADILY NORTHEASTWARD DURING THE PREDAWN AND EARLY
MORNING HOURS BUT HAVE TAKEN ON A MORE EASTERLY DIRECTION OVER
THE LAST FEW HOURS AS THEY HAVE APPROACHED THE TOP OF A FLAT
UPPER RIDGE OVER THE LOCAL AREA IN THE WAKE OF THE COMPACT UPPER
LOW THAT HAD MOVED FROM OVER SOUTHERN LAKE MI TO WESTERN LAKE
ERIE SINCE LATE LAST NIGHT.
THIS CURRENT CONVECTION APPEARS TO BE WHERE LOWER AND MID LEVEL
WAA ARE MAXIMIZING ISENTROPIC ASCENT IN AN AREA OF STEEP MID
LEVEL LAPSE RATES. FORCING IN AN COINCIDING WITH AN AREA OF STEEP
MID LEVEL LAPSE RATES. LOWER AND MID LEVEL THETA-E ADVECTION
APPEARS TO BE ALSO HELPING IN THE TURN TO A MORE EASTERLY
MOVEMENT.
PURE EXTRAPOLATION OF THIS RECENT MOVEMENT WOULD LEAD ONE TO
BELIEVE THAT THE TSRA WOULD CONTINUE ACROSS NW TO N CENTRAL IL
AND NE IL DURING THE LATE MORNING THROUGH MID AFTERNOON.
HOWEVER...HIGHER RESOLUTION SHORT TERM MODEL OUTPUT INCLUDING
CONVECTIVE PRECIP...850-700 EQ POT TEMP ADV...K INDEX MID LEVEL
LAPSE RATES ARE SUGGESTING THAT THIS ACTIVITY WILL MAINTAIN AN
OVERALL ENE TO NE MOVEMENT PUTTING JUST N CENTRAL AND FAR NE IL
AT ANY SIGNIFICANT RISK OF SEEING THUNDERSTORMS.
WITH THE QUICK CLEARING FOLLOWING THE DEPARTURE OF THE UPPER LOW
EARLY THIS MORNING TEMPERATURES RESPONDED BY QUICKLY RISING INTO
THE LOWER AND MID 70S. WHILE SOME OF THE ANVIL FROM THE TS
CLUSTER IN FAR E CENTRAL IA IS EXPECTED TO MOVE THE NORTH PORTION
OF THE FA DURING THE AFTERNOON AND CUT INTO THE SURFACE
HEATING...FORECAST SOUNDINGS PREDICT HIGHS IN THE LOWER AND MID
80S... EXCEPT ALONG THE NORTH LAKE SHORE WHERE A LAKE BREEZE
EXPECTED TO MAKE LITTLE INLAND ADVANCEMENT KEEPS THIS AREA IN THE
MID 70S.
TRS
&&
.PREV DISCUSSION...
330 AM CDT
THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.
SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.
TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.
SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.
TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.
THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.
THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* SPOTTY SHOWERS POSSIBLE THROUGH THE MORNING...ALSO WATCHING
ACTIVITY ACROSS EASTERN IA WHICH LOOKS TO REMAIN NW OF THE
TERMINALS EARLY AFTERNOON.
* SSE WINDS TURNING SSW...WITH GUSTS TO NEAR 20 KT POSSIBLE LATER
THIS AFTERNOON.
* LOW CHANCE FOR SHRA/TSRA EARLY THURSDAY MORNING.
MDB
//DISCUSSION...UPDATED 14Z...
LOWEST VFR CIGS CONTINUE TO SCATTER ACROSS THE CHICAGO AREA BUT
SPOTTY SHOWERS CONTINUE TO DEVELOP AND WILL LIKELY CONTINUE TO DO
SO FOR A FEW HOURS. AM WATCHING CLUSTER OF SHRA/TSRA OVER EASTERN
IA WHICH HAS HAD SOME SCATTERED EXPANSION SOUTHWARD TOWARD KMUT
AND KFSW BUT AM EXPECTING THIS TO AIM MORE NORTHEASTWARD WITH TIME
IN CONJUNCTION WITH BETTER LOW/MID LEVEL ASCENT. WILL NEED TO
MONITOR BUT IT DOES APPEAR THAT THE SOUTHERN END OF THIS WILL PASS
NEAR OR OVER RFD BY MIDDAY WITH IT THEN PASSING NW OF THE CHI AREA
TERMINALS EARLY AFTERNOON. IF THERE IS ADDITIONAL SOUTHWARD
DEVELOPMENT THEN THE CHANCE OF ORD/DPA BEING AFFECTED WOULD
INCREASE. WINDS MAY TAKE A LITTLE LONGER TO TURN SSW THAN TAF
INDICATES.
MDB
FROM 12Z...
A WEAK SHORTWAVE MOVING ACROSS THE AREA COMBINED WITH WARM
ADVECTION HAS GENERATED SOME ISOLATED SHOWERS ACROSS THE REGION.
HOWEVER...THE STRONGEST FOCUS WILL ALIGN FROM NERN IOWA INTO
CENTRAL WISCONSIN...AND GENERALLY NORTH OF THE WISCONSIN BORDER.
HOWEVER...LATEST RADAR AND SATELLITE IMAGERY HAS INDICATED SOME
DEVELOPMENT OVER THE RFD AREA...SO...WILL KEEP SOME MENTION OF
PCPN IN THE FORECAST FOR THE RFD TERMINAL. OTHERWISE...EXPECT THE
REMAINDER OF THE TERMINALS TO REMAIN DRY TODAY. THERE WILL BE
ANOTHER CHANCE FOR SOME PCPN EARLY TOMORROW MORNING AS ANOTHER
SHORTWAVE CROSSES THE AREA...HOWEVER...THE GUIDANCE HAS NOT BEEN
VERY CONSISTENT IN THE THIS PCPN SIGNAL...SO CONFIDENCE IS LOW
THAT THE TERMINALS WILL BE DIRECTLY IMPACTED.
THE OTHER MAIN CONCERN FOR TODAY WILL BE WINDS. AS A LARGE AREA OF
HIGH PRESSURE SLIDES OFF THE MID ATLANTIC COAST...AND A SFC LOW
DEVELOPS OVER THE NRN PLAINS...A SOUTHERLY GRADIENT WILL STRENGTHEN
THROUGH THE DAY. WINDS WILL START OUT SELY THIS MORNING...BUT AS A
WEAK WARM FRONT LIFTS NWD...WINDS WILL VEER TO SLY AND STRENGTHEN
TO 10-12KT SUSTAINED. THROUGH THE MORNING...BREAKS IN THE
CLOUDINESS WILL ALLOW FOR SOME SUNSHINE AND INCREASED LOW LEVEL
MIXING AND STRONGER WINDS SHOULD BE ABLE TO MIX DOWN TO THE
SURFACE. LATEST SOUNDINGS SUGGEST THAT GUSTS SHOULD INCREASE FROM
LATE MORNING INTO THE AFTERNOON...WITH PEAK GUSTS TO ARND 20KT
THIS AFTERNOON.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* HIGH CONFIDENCE THAT MORNING SHOWER ACTIVITY WILL REMAIN SPOTTY.
MEDIUM CONFIDENCE THAT IA ACTIVITY WILL PASS TO THE NW...BUT
WILL NEED TO KEEP AN EYE ON IT FOR EARLY AFTERNOON.
* MEDIUM-HIGH CONFIDENCE IN SSE WINDS TURNING SSW...LOW CONFIDENCE
IN TIMING.
* MEDIUM CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY MORNING IS
LOW.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.
FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.
SATURDAY THROUGH TUESDAY...VFR. WX NIL.
KREIN
&&
.MARINE...
255 AM CDT
A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
855 AM CDT WED SEP 18 2013
.DISCUSSION...
330 AM CDT
THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.
SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.
TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.
SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.
TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.
THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.
THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* SPOTTY SHOWERS POSSIBLE THROUGH THE MORNING...ALSO WATCHING
ACTIVITY ACROSS EASTERN IA WHICH LOOKS TO REMAIN NW OF THE
TERMINALS EARLY AFTERNOON.
* SSE WINDS TURNING SSW...WITH GUSTS TO NEAR 20 KT POSSIBLE LATER
THIS AFTERNOON.
* LOW CHANCE FOR SHRA/TSRA EARLY THURSDAY MORNING.
MDB
//DISCUSSION...UPDATED 14Z...
LOWEST VFR CIGS CONTINUE TO SCATTER ACROSS THE CHICAGO AREA BUT
SPOTTY SHOWERS CONTINUE TO DEVELOP AND WILL LIKELY CONTINUE TO DO
SO FOR A FEW HOURS. AM WATCHING CLUSTER OF SHRA/TSRA OVER EASTERN
IA WHICH HAS HAD SOME SCATTERED EXPANSION SOUTHWARD TOWARD KMUT
AND KFSW BUT AM EXPECTING THIS TO AIM MORE NORTHEASTWARD WITH TIME
IN CONJUNCTION WITH BETTER LOW/MID LEVEL ASCENT. WILL NEED TO
MONITOR BUT IT DOES APPEAR THAT THE SOUTHERN END OF THIS WILL PASS
NEAR OR OVER RFD BY MIDDAY WITH IT THEN PASSING NW OF THE CHI AREA
TERMINALS EARLY AFTERNOON. IF THERE IS ADDITIONAL SOUTHWARD
DEVELOPMENT THEN THE CHANCE OF ORD/DPA BEING AFFECTED WOULD
INCREASE. WINDS MAY TAKE A LITTLE LONGER TO TURN SSW THAN TAF
INDICATES.
MDB
FROM 12Z...
A WEAK SHORTWAVE MOVING ACROSS THE AREA COMBINED WITH WARM
ADVECTION HAS GENERATED SOME ISOLATED SHOWERS ACROSS THE REGION.
HOWEVER...THE STRONGEST FOCUS WILL ALIGN FROM NERN IOWA INTO
CENTRAL WISCONSIN...AND GENERALLY NORTH OF THE WISCONSIN BORDER.
HOWEVER...LATEST RADAR AND SATELLITE IMAGERY HAS INDICATED SOME
DEVELOPMENT OVER THE RFD AREA...SO...WILL KEEP SOME MENTION OF
PCPN IN THE FORECAST FOR THE RFD TERMINAL. OTHERWISE...EXPECT THE
REMAINDER OF THE TERMINALS TO REMAIN DRY TODAY. THERE WILL BE
ANOTHER CHANCE FOR SOME PCPN EARLY TOMORROW MORNING AS ANOTHER
SHORTWAVE CROSSES THE AREA...HOWEVER...THE GUIDANCE HAS NOT BEEN
VERY CONSISTENT IN THE THIS PCPN SIGNAL...SO CONFIDENCE IS LOW
THAT THE TERMINALS WILL BE DIRECTLY IMPACTED.
THE OTHER MAIN CONCERN FOR TODAY WILL BE WINDS. AS A LARGE AREA OF
HIGH PRESSURE SLIDES OFF THE MID ATLANTIC COAST...AND A SFC LOW
DEVELOPS OVER THE NRN PLAINS...A SOUTHERLY GRADIENT WILL STRENGTHEN
THROUGH THE DAY. WINDS WILL START OUT SELY THIS MORNING...BUT AS A
WEAK WARM FRONT LIFTS NWD...WINDS WILL VEER TO SLY AND STRENGTHEN
TO 10-12KT SUSTAINED. THROUGH THE MORNING...BREAKS IN THE
CLOUDINESS WILL ALLOW FOR SOME SUNSHINE AND INCREASED LOW LEVEL
MIXING AND STRONGER WINDS SHOULD BE ABLE TO MIX DOWN TO THE
SURFACE. LATEST SOUNDINGS SUGGEST THAT GUSTS SHOULD INCREASE FROM
LATE MORNING INTO THE AFTERNOON...WITH PEAK GUSTS TO ARND 20KT
THIS AFTERNOON.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* HIGH CONFIDENCE THAT MORNING SHOWER ACTIVITY WILL REMAIN SPOTTY.
MEDIUM CONFIDENCE THAT IA ACTIVITY WILL PASS TO THE NW...BUT
WILL NEED TO KEEP AN EYE ON IT FOR EARLY AFTERNOON.
* MEDIUM-HIGH CONFIDENCE IN SSE WINDS TURNING SSW...LOW CONFIDENCE
IN TIMING.
* MEDIUM CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY MORNING IS
LOW.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.
FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.
SATURDAY THROUGH TUESDAY...VFR. WX NIL.
KREIN
&&
.MARINE...
255 AM CDT
A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
618 AM CDT WED SEP 18 2013
.DISCUSSION...
330 AM CDT
THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.
SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.
TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.
SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.
TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.
THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.
THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* SLIGHT CHANCE FOR A FEW ISOLATED SHOWERS THROUGH LATE MORNING.
* ANOTHER SLIGHT CHANCE FOR SHOWERS OR THUNDERSTORMS EARLY
TOMORROW MORNING.
* SOUTHERLY WINDS GUSTING TO ARND 20KT. STRONGEST GUSTS IN THE
LATE AFTERNOON.
KREIN
//DISCUSSION...UPDATED 12Z...
A WEAK SHORTWAVE MOVING ACROSS THE AREA COMBINED WITH WARM
ADVECTION HAS GENERATED SOME ISOLATED SHOWERS ACROSS THE REGION.
HOWEVER...THE STRONGEST FOCUS WILL ALIGN FROM NERN IOWA INTO
CENTRAL WISCONSIN...AND GENERALLY NORTH OF THE WISCONSIN BORDER.
HOWEVER...LATEST RADAR AND SATELLITE IMAGERY HAS INDICATED SOME
DEVELOPMENT OVER THE RFD AREA...SO...WILL KEEP SOME MENTION OF
PCPN IN THE FORECAST FOR THE RFD TERMINAL. OTHERWISE...EXPECT THE
REMAINDER OF THE TERMINALS TO REMAIN DRY TODAY. THERE WILL BE
ANOTHER CHANCE FOR SOME PCPN EARLY TOMORROW MORNING AS ANOTHER
SHORTWAVE CROSSES THE AREA...HOWEVER...THE GUIDANCE HAS NOT BEEN
VERY CONSISTENT IN THE THIS PCPN SIGNAL...SO CONFIDENCE IS LOW
THAT THE TERMINALS WILL BE DIRECTLY IMPACTED.
THE OTHER MAIN CONCERN FOR TODAY WILL BE WINDS. AS A LARGE AREA OF
HIGH PRESSURE SLIDES OFF THE MID ATLANTIC COAST...AND A SFC LOW
DEVELOPS OVER THE NRN PLAINS...A SOUTHERLY GRADIENT WILL STRENGTHEN
THROUGH THE DAY. WINDS WILL START OUT SELY THIS MORNING...BUT AS A
WEAK WARM FRONT LIFTS NWD...WINDS WILL VEER TO SLY AND STRENGTHEN
TO 10-12KT SUSTAINED. THROUGH THE MORNING...BREAKS IN THE
CLOUDINESS WILL ALLOW FOR SOME SUNSHINE AND INCREASED LOW LEVEL
MIXING AND STRONGER WINDS SHOULD BE ABLE TO MIX DOWN TO THE
SURFACE. LATEST SOUNDINGS SUGGEST THAT GUSTS SHOULD INCREASE FROM
LATE MORNING INTO THE AFTERNOON...WITH PEAK GUSTS TO ARND 20KT
THIS AFTERNOON.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* LOW CONFIDENCE IN SHRA DIRECTLY IMPACTING THE TERMINALS...AND
MEDIUM CONFIDENCE THAT THE TERMINALS WILL REMAIN DRY.
* MEDIUM CONFIDENCE IN CIG TRENDS.
* MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS.
KREIN
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.
FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.
SATURDAY THROUGH TUESDAY...VFR. WX NIL.
KREIN
&&
.MARINE...
255 AM CDT
A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1032 AM EDT WED SEP 18 2013
.UPDATE...
AVIATION SECTION UPDATED
&&
.SYNOPSIS...
ISSUED AT 330 AM EDT WED SEP 18 2013
A COLD FRONT WILL DROP SOUTHEAST ACROSS CENTRAL INDIANA FRIDAY
NIGHT. THE FRONT WILL INTERACT WITH WARM...MOIST AND UNSTABLE AIR
WHICH WILL RESULT IN THUNDERSTORM CHANCES STARTING TODAY. THE BEST
CHANCES WILL BE FRIDAY AND FRIDAY NIGHT AS THE FRONT GETS CLOSER.
THE SOUTHERLY FLOW WILL ALSO RESULT IN ABOVE NORMAL
TEMPERATURES...MOSTLY IN THE 80S. THEN...DRY WEATHER WILL RETURN BY
SATURDAY AS HIGH PRESSURE SETTLES EAST ACROSS THE GREAT LAKES WITH
COOLER TEMPERATURES IN THE 70S FOR AFTERNOON HIGHS.
&&
.NEAR TERM /TODAY/...
ISSUED AT 942 AM EDT WED SEP 18 2013
INTRODUCED LIKELIES INTO THE SOUTHWESTERN FORECAST AREA THROUGH
MIDDAY FOR THE AREA OF SHOWERS PUSHING INTO THAT AREA. HRRR TAKES
THIS THROUGH THE SOUTHWEST/SOUTH CENTRAL AREA AS IT WEAKENS LATER
THIS MORNING. AT LEAST A STRIKE OR TWO DETECTED SO WILL CONTINUE
ISOLATED THUNDER MENTION. ALSO REDUCED MAX TEMPS IN THAT AREA
OWING TO INFLUENCE OF RAIN COOLED AIR DURING WHAT WOULD ORDINARILY
BE BEST TIME FOR HEATING. PREVIOUS DISCUSSION FOLLOWS.
ISSUED AT 330 AM EDT WED SEP 18 2013
MAIN FOCUS TODAY WILL BE ON POPS. RADAR WAS SHOWING A GROUP OF
SHOWERS MOVING EAST AND NORTHEAST ACROSS NORTHWESTERN INDIANA AND
ARE ASSOCIATED WITH A WEAK WAVE ALOFT IN OTHERWISE MODEST ZONAL
FLOW. IN ADDITION...THERE WAS SOME ACTIVITY ACROSS SOUTHERN ILLINOIS
AND ALSO NEAR ST. LOUIS ASSOCIATED WITH ANOTHER WEAK WAVE THAT WILL
MOVE EAST ACROSS SOUTH CENTRAL INDIANA THIS MORNING. WEAK ISENTROPIC
LIFT WILL CONTINUE ALL THE WHILE...AND MODEL SOUNDINGS WERE
INDICATING DEEPENING MOISTURE. THE 05Z RAPID REFRESH WAS GOING
BONKERS WITH WIDESPREAD RAIN THIS MORNING...BLOWING UP THE SOUTHERN
ILLINOIS SHOWERS. THAT BEING SAID...DID RAISE POPS TO 30 PERCENT OR
MORE EXCEPT ACROSS OUR FAR EAST DO MAINLY TO RADAR TRENDS.
INSTABILITY IS PROGGED TO BE WEAK OR ABSENT TODAY...SO ONLY
MENTIONED ISOLATED THUNDER.
SHOULD BE DECENT CLOUD COVER TODAY...SO PREFER AT OR BELOW CONSALL
AND ALLBLEND.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
ISSUED AT 330 AM EDT WED SEP 18 2013
FOCUS WILL CONTINUE TO BE ON POPS THROUGH THE ENTIRE SHORT TERM.
MODELS ARE SIMILAR IN BRINGING A COLD FRONT SOUTHEAST ACROSS CENTRAL
INDIANA FRIDAY NIGHT AS A VIGOROUS UPPER TROUGH PROGRESSES EAST
ACROSS SOUTHERN CANADA. UPPER RIDGE WILL SETTLE ACROSS CENTRAL
INDIANA THURSDAY...WITH RETURN FLOW ACROSS THE OHIO VALLEY AROUND
EAST COAST HIGH PRESSURE. THIS WILL RESULT A VERY UNSTABLE
ATMOSPHERE ON THURSDAY WITH CAPES ABOVE 2000 J/KG. STILL...PLENTY OF
INSTABILITY THROUGH THE ENTIRE EXTENDED FOR THUNDER. WITH ONLY WEAK
SYNOPTIC FORCING...WILL ONLY GO WITH SMALL POPS UNTIL FRIDAY AFTER
THE UPPER RIDGE PASSES AND THE COLD FRONT AND UPPER TROUGH GET
CLOSER. THEN...LIKELY POPS FROM CONSALL...ALLBLEND AND MOS BLEND
LOOK GOOD AS MODEL UPWARD VERTICAL MOTION AND QPF PROGS SUGGEST
LINEAR CONVECTION LATE FRIDAY AFTERNOON AND NIGHT. WOULD NOT RULE
OUT STRONG OR EVEN ISOLATED SEVERE STORMS AS FRIDAY AND FRIDAY NIGHT.
TEMPERATURES WITH THE CLOUD COVER WILL BE TRICKY...BUT OVERALL ALL
BLEND LOOKS DECENT AND MATCHES UP WELL WITH ADJACENT OFFICES.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
ISSUED AT 330 AM EDT WED SEP 18 2013
ENSEMBLES INDICATE A RATHER STRONG UPPER TROUGH WILL BE MOVING
THROUGH THE GREAT LAKES ON SATURDAY. ALTHOUGH IT APPEARS THAT THE
ASSOCIATED COLD FRONT WILL BE EAST OF THE AREA BY SATURDAY...SEVERAL
ENSEMBLES CUTOFF THE SOUTHERN PORTION OF THE TROUGH OVER THE OHIO
VALLEY ON SATURDAY...WITH THIS CUTOFF EVENTUALLY SINKING INTO THE
SOUTHEAST PORTIONS OF THE COUNTRY BY EARLY NEXT WEEK. THIS MAY
PROLONG THE PRECIPITATION THREAT INTO SATURDAY. WILL GO WITH CHANCE
POPS ON SATURDAY TO COVER THIS.
OTHERWISE...UPPER RIDGING EXPECTED TO BUILD ACROSS THE AREA THROUGH
THE MIDDLE OF NEXT WEEK AS LONG WAVE TROUGHING DEVELOPS OVER THE
WEST. WILL GO DRY AFTER SATURDAY.
&&
.AVIATION /DISCUSSION FOR THE 181500Z IN TAF UPDATE/...
ONGOING TAFS IN PRETTY GOOD SHAPE. RADAR TRENDS SHOW AN AREA OF
SHRA OVER SW INDIANA...POISED TO BRUSH HUF AND PUSH ACROSS THE BMG
TAF SITES. ONGOING TEMPS GROUPS HAND THAT WELL. AT THE MOMENT NO
THUNDER APPEARS PRESENT AND WILL KEEP THE TSRA MENTION OUT OF THE
FORECAST.
PREVIOUS DISCUSSION BELOW
/DISCUSSION FOR THE 181200Z TAFS/...
ISSUED AT 629 AM EDT WED SEP 18 2013
UPPER WAVE CURRENTLY MOVING THROUGH SOUTHERN ILLINOIS IS EXPECTED TO
MOVE ACROSS SOUTHERN INDIANA LATER TODAY AND GRADUALLY WEAKEN BASED
ON MODEL DATA. ALTHOUGH THIS FEATURE EXPECTED TO WEAKEN...THERE IS
CURRENTLY QUITE OF BIT OF RAIN ASSOCIATED WITH THIS FEATURE. AS A
RESULT...THINK THE CHANCES ARE PRETTY GOOD FOR A PERIOD OF LIGHT
RAIN...MAINLY IN THE KHUF/KBMG AREAS ROUGHLY 181300Z-181800Z. LOWER
CHANCES AT KIND/KLAF. RAIN SHOULD BE LIGHT ENOUGH THAT IT SHOULDN/T
RESTRICT VISIBILITIES THAT MUCH...ALTHOUGH SOME CEILINGS AROUND 040
POSSIBLE NEAR THE RAIN AREAS. CONVECTIVE PARAMETERS TODAY NOT
IMPRESSIVE IN THE IMMEDIATE AREA...BUT ARE MORE FAVORABLE THIS
AFTERNOON TO THE SOUTHWEST OF KHUF/KBMG.
OTHERWISE...CEILINGS GENERALLY ABOVE 050 TODAY WITH NO WIND ISSUES
EXPECTED AT THE TAF SITES THROUGH 190000Z.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MK
NEAR TERM...MK/NIELD
SHORT TERM...MK
LONG TERM....JAS
AVIATION...JAS/JP
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FOLLOW US ON TWITTER AND YOUTUBE AT:
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AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
942 AM EDT WED SEP 18 2013
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 330 AM EDT WED SEP 18 2013
A COLD FRONT WILL DROP SOUTHEAST ACROSS CENTRAL INDIANA FRIDAY
NIGHT. THE FRONT WILL INTERACT WITH WARM...MOIST AND UNSTABLE AIR
WHICH WILL RESULT IN THUNDERSTORM CHANCES STARTING TODAY. THE BEST
CHANCES WILL BE FRIDAY AND FRIDAY NIGHT AS THE FRONT GETS CLOSER.
THE SOUTHERLY FLOW WILL ALSO RESULT IN ABOVE NORMAL
TEMPERATURES...MOSTLY IN THE 80S. THEN...DRY WEATHER WILL RETURN BY
SATURDAY AS HIGH PRESSURE SETTLES EAST ACROSS THE GREAT LAKES WITH
COOLER TEMPERATURES IN THE 70S FOR AFTERNOON HIGHS.
&&
.NEAR TERM /TODAY/...
ISSUED AT 942 AM EDT WED SEP 18 2013
INTRODUCED LIKELIES INTO THE SOUTHWESTERN FORECAST AREA THROUGH
MIDDAY FOR THE AREA OF SHOWERS PUSHING INTO THAT AREA. HRRR TAKES
THIS THROUGH THE SOUTHWEST/SOUTH CENTRAL AREA AS IT WEAKENS LATER
THIS MORNING. AT LEAST A STRIKE OR TWO DETECTED SO WILL CONTINUE
ISOLATED THUNDER MENTION. ALSO REDUCED MAX TEMPS IN THAT AREA
OWING TO INFLUENCE OF RAIN COOLED AIR DURING WHAT WOULD ORDINARILY
BE BEST TIME FOR HEATING. PREVIOUS DISCUSSION FOLLOWS.
ISSUED AT 330 AM EDT WED SEP 18 2013
MAIN FOCUS TODAY WILL BE ON POPS. RADAR WAS SHOWING A GROUP OF
SHOWERS MOVING EAST AND NORTHEAST ACROSS NORTHWESTERN INDIANA AND
ARE ASSOCIATED WITH A WEAK WAVE ALOFT IN OTHERWISE MODEST ZONAL
FLOW. IN ADDITION...THERE WAS SOME ACTIVITY ACROSS SOUTHERN ILLINOIS
AND ALSO NEAR ST. LOUIS ASSOCIATED WITH ANOTHER WEAK WAVE THAT WILL
MOVE EAST ACROSS SOUTH CENTRAL INDIANA THIS MORNING. WEAK ISENTROPIC
LIFT WILL CONTINUE ALL THE WHILE...AND MODEL SOUNDINGS WERE
INDICATING DEEPENING MOISTURE. THE 05Z RAPID REFRESH WAS GOING
BONKERS WITH WIDESPREAD RAIN THIS MORNING...BLOWING UP THE SOUTHERN
ILLINOIS SHOWERS. THAT BEING SAID...DID RAISE POPS TO 30 PERCENT OR
MORE EXCEPT ACROSS OUR FAR EAST DO MAINLY TO RADAR TRENDS.
INSTABILITY IS PROGGED TO BE WEAK OR ABSENT TODAY...SO ONLY
MENTIONED ISOLATED THUNDER.
SHOULD BE DECENT CLOUD COVER TODAY...SO PREFER AT OR BELOW CONSALL
AND ALLBLEND.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
ISSUED AT 330 AM EDT WED SEP 18 2013
FOCUS WILL CONTINUE TO BE ON POPS THROUGH THE ENTIRE SHORT TERM.
MODELS ARE SIMILAR IN BRINGING A COLD FRONT SOUTHEAST ACROSS CENTRAL
INDIANA FRIDAY NIGHT AS A VIGOROUS UPPER TROUGH PROGRESSES EAST
ACROSS SOUTHERN CANADA. UPPER RIDGE WILL SETTLE ACROSS CENTRAL
INDIANA THURSDAY...WITH RETURN FLOW ACROSS THE OHIO VALLEY AROUND
EAST COAST HIGH PRESSURE. THIS WILL RESULT A VERY UNSTABLE
ATMOSPHERE ON THURSDAY WITH CAPES ABOVE 2000 J/KG. STILL...PLENTY OF
INSTABILITY THROUGH THE ENTIRE EXTENDED FOR THUNDER. WITH ONLY WEAK
SYNOPTIC FORCING...WILL ONLY GO WITH SMALL POPS UNTIL FRIDAY AFTER
THE UPPER RIDGE PASSES AND THE COLD FRONT AND UPPER TROUGH GET
CLOSER. THEN...LIKELY POPS FROM CONSALL...ALLBLEND AND MOS BLEND
LOOK GOOD AS MODEL UPWARD VERTICAL MOTION AND QPF PROGS SUGGEST
LINEAR CONVECTION LATE FRIDAY AFTERNOON AND NIGHT. WOULD NOT RULE
OUT STRONG OR EVEN ISOLATED SEVERE STORMS AS FRIDAY AND FRIDAY NIGHT.
TEMPERATURES WITH THE CLOUD COVER WILL BE TRICKY...BUT OVERALL ALL
BLEND LOOKS DECENT AND MATCHES UP WELL WITH ADJACENT OFFICES.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
ISSUED AT 330 AM EDT WED SEP 18 2013
ENSEMBLES INDICATE A RATHER STRONG UPPER TROUGH WILL BE MOVING
THROUGH THE GREAT LAKES ON SATURDAY. ALTHOUGH IT APPEARS THAT THE
ASSOCIATED COLD FRONT WILL BE EAST OF THE AREA BY SATURDAY...SEVERAL
ENSEMBLES CUTOFF THE SOUTHERN PORTION OF THE TROUGH OVER THE OHIO
VALLEY ON SATURDAY...WITH THIS CUTOFF EVENTUALLY SINKING INTO THE
SOUTHEAST PORTIONS OF THE COUNTRY BY EARLY NEXT WEEK. THIS MAY
PROLONG THE PRECIPITATION THREAT INTO SATURDAY. WILL GO WITH CHANCE
POPS ON SATURDAY TO COVER THIS.
OTHERWISE...UPPER RIDGING EXPECTED TO BUILD ACROSS THE AREA THROUGH
THE MIDDLE OF NEXT WEEK AS LONG WAVE TROUGHING DEVELOPS OVER THE
WEST. WILL GO DRY AFTER SATURDAY.
&&
.AVIATION /DISCUSSION FOR THE 181200Z TAFS/...
ISSUED AT 629 AM EDT WED SEP 18 2013
UPPER WAVE CURRENTLY MOVING THROUGH SOUTHERN ILLINOIS IS EXPECTED TO
MOVE ACROSS SOUTHERN INDIANA LATER TODAY AND GRADUALLY WEAKEN BASED
ON MODEL DATA. ALTHOUGH THIS FEATURE EXPECTED TO WEAKEN...THERE IS
CURRENTLY QUITE OF BIT OF RAIN ASSOCIATED WITH THIS FEATURE. AS A
RESULT...THINK THE CHANCES ARE PRETTY GOOD FOR A PERIOD OF LIGHT
RAIN...MAINLY IN THE KHUF/KBMG AREAS ROUGHLY 181300Z-181800Z. LOWER
CHANCES AT KIND/KLAF. RAIN SHOULD BE LIGHT ENOUGH THAT IT SHOULDN/T
RESTRICT VISIBILITIES THAT MUCH...ALTHOUGH SOME CEILINGS AROUND 040
POSSIBLE NEAR THE RAIN AREAS. CONVECTIVE PARAMETERS TODAY NOT
IMPRESSIVE IN THE IMMEDIATE AREA...BUT ARE MORE FAVORABLE THIS
AFTERNOON TO THE SOUTHWEST OF KHUF/KBMG.
OTHERWISE...CEILINGS GENERALLY ABOVE 050 TODAY WITH NO WIND ISSUES
EXPECTED AT THE TAF SITES THROUGH 190000Z.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...MK
NEAR TERM...MK/NIELD
SHORT TERM...MK
LONG TERM....JAS
AVIATION...JAS
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
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AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
601 AM CDT WED SEP 18 2013
.UPDATED FOR 12Z AVIATION DISCUSSION...
ISSUED AT 547 AM CDT WED SEP 18 2013
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT WED SEP 18 2013
AN AREA OF LOW PRESSURE WAS LOCATED OVER THE WESTERN DAKOTAS...WITH
HIGH PRESSURE ACROSS THE EASTERN SEABOARD. THIS SETUP RESULTED IN
SOUTHERLY FLOW ACROSS THE UPPER MIDWEST WAS BRINGING WARM MOIST AIR
TO THE REGION. THIS WAA WAS EASILY IDENTIFIED BY LOOKING AT THE H850
TEMPERATURE ADVECTION OFF THE SPC MESOANALYSIS PAGE. THE LOW LEVEL
MOISTURE WAS EVIDENT BY THE STRATUS DECK THAT COVERED THE ENTIRE
UPPER MISSISSIPPI RIVER VALLEY WITH POCKETS OF DRIZZLE AND FOG. A
FEW AREAS OF ELEVATED CONVECTION MANAGED TO DEVELOP ALONG THE
EAST/WEST MUCAPE GRADIENT. SINCE THESE STORMS WERE ELEVATED...THEY
WERE UNABLE TO TAKE ADVANTAGE OF THE 0-1KM SHEAR AND HELICITY OF
30KTS AND 300M2/S2 RESPECTIVELY...AND DRIFTED HARMLESSLY EAST
NORTHEAST WITH THE MEAN WIND.
MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING HOW THE STATUS FIELD
WILL EVOLVE TODAY. H850 TEMPS WILL INCREASE FROM AROUND 12-15C EARLY
THIS MORNING...TO 20-22C THIS AFTERNOON. THAT WARM LAYER ALOFT WILL
ONLY ENHANCE THE CAPPING INVERSION AND LIMIT MIXING THIS AFTERNOON.
AS A RESULT IT MAY BE DIFFICULT TO LOOSE THE CLOUDS...WHICH IN TURN
WILL HAMPER TODAYS HIGH TEMPERATURES. MOST LIKELY IT WILL EITHER BE
BOOM OR BUST WITH HIGHS TODAY. THE NAM AND HRRR CLEAR OUT THE
CLOUDS BY EARLY THIS AFTERNOON WHICH WOULD FAVOR A WARMER SOLUTION.
HOWEVER...JUST WITHIN THE INDIVIDUAL MEMBERS OF THE SREF THE HIGH
TEMPERATURE TODAY VARIES FROM 89 TO 77 AT KMSP. MEMBER 2 OF THE
HOPWRF KEEPS THE CLOUDS ACROSS THE CWA THROUGH 21Z THIS
AFTERNOON...SO HAVE TRENDED BACK TEMPERATURES SLIGHTLY TO REFLECT
THE MORE CLOUDY SCENARIO. AS THE WARM FRONT LIFT NORTHWARD THIS
AFTERNOON AND OVERNIGHT PRECIP CHANCES WILL DECREASE FROM SOUTH TO
NORTH...BUT RETURN AGAIN EARLY THURSDAY MORNING AS THE COLD FRONT
APPROACHES FROM THE WEST.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 328 AM CDT WED SEP 18 2013
SHOWERS AND SOME THUNDERSTORMS WILL LIKELY BE ONGOING ACROSS THE
FAR EASTERN DAKOTAS AND WESTERN MINNESOTA THURSDAY MORNING. MOIST
SOUTHERLY FLOW WITH PW VALUES OF 1.5 TO 1.8 INCHES...ROUGHLY 220
PERCENT OF NORMAL...AND 850 MB TEMPS OF +20C WILL OVERSPREAD THE
REGION. THE CAPPING INVERSION PRODUCED BY THIS ABUNDANCE OF WARM
AIR ALOFT WILL LIKELY CONTRIBUTE TO CONSIDERABLE CLOUDINESS
THROUGH MUCH OF THE DAY WITH LITTLE HOPE OF DEEP MIXING AND
ERODING THE CAP SUFFICIENTLY AHEAD OF THE FRONT. THIS WILL PROVE
DETRIMENTAL ON WIDESPREAD CONVECTIVE CHANCES TO SOME
DEGREE...UNLESS SURFACE TEMPS DO WARM INTO THE 80S. BEST POTENTIAL
FOR THIS WOULD BE ACROSS WESTERN WI AS FROPA WILL TAKE PLACE LATE
IN THE DAY. MID LEVEL LAPSE RATES WILL CONTRIBUTE TO AROUND 2000
J/KG MLCAPE...SO IF THE CAP DOES ERODE...WIDESPREAD THUNDERSTORMS
CAN BE EXPECTED. MODEST SPEED SHEAR WOULD ALSO HELP ORGANIZE A FEW
STORMS ENOUGH FOR A MARGINAL SEVERE THREAT.
COOLER AND DRIER AIR WILL FOLLOW THURSDAY NIGHT INTO SATURDAY. AS
THE HIGH PUSHES OVERHEAD FRIDAY NIGHT...TEMPERATURES COULD FALL
INTO THE 30S IN SOME LOCATIONS IF WINDS DECOUPLE.
RETURN FLOW WILL COMMENCE SATURDAY NIGHT AND STRENGTHEN INTO EARLY
NEXT WEEK AS TROUGHING DIGS INTO THE PACIFIC NORTHWEST. SOUTHWEST
FLOW WILL KEEP THE STORM TRACK WEST OF THE REGION...AND COLD
FRONTS/DISTURBANCES PUSHING THROUGH WILL NOT HAVE MUCH PUNCH. ONE
SUCH FRONT IS PROGGED FOR MONDAY AND MONDAY NIGHT...WITH THE ECMWF
THE STRONGEST OF ALL GUIDANCE. ONLY LOW POPS WERE JUSTIFIED.
TEMPERATURES WILL BE ABOVE AVERAGE EARLY NEXT WEEK...AND 80S MAY
RETURN FOR MIDWEEK WITH 925 MB TEMPS CLIMBING INTO THE 20S C.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 547 AM CDT WED SEP 18 2013
AN AREA OF LOW PRESSURE WAS LOCATED OVER THE DAKOTAS...WITH
SOUTHERLY FLOW AND LOW CLOUDS ACROSS MN/WI. THE LIFR STRATUS WILL
LINGER ACROSS THE REGION THIS MORNING...AND ERODE FROM THE SOUTH
THIS AFTERNOON. LATER TONIGHT WILL LIKELY SEE LIFR CONDITIONS
AGAIN ALONG THE APPROACHING FRONTAL BOUNDARY. THIS FRONT WILL BE
THE FOCUS FOR A FEW SHOWERS AND THUNDERSTORMS AS WELL EARLY
THURSDAY MORNING.
KMSP...
FORECAST GUIDANCE CONTINUE TO SHOW LIFR CONDITIONS PREVAILING THIS
MORNING...WITH A SLIGHT IMPROVEMENT TO IFR BY LATE MORNING. THE
HOPWRF HIRES MODEL ERODES THE STRATUS FROM THE SOUTHWEST...AND THE
CLEARING SHOULD REACH THE METRO AREA AROUND 20Z. WINDS WILL BE
SOUTH SOUTHEASTERLY TODAY. A COLD FRONT WILL APPROACH FROM THE
WEST THURSDAY MORNING...AND BRING A CHANCE FOR SHOWERS AND
THUNDERSTORMS.
/OUTLOOK FOR KMSP/
FRI...VFR. WINDS NW 15G25KT.
SAT...VFR. WINDS NW 5-10KT.
SUN...VFR. WINDS SE AT 15G20KT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...JRB
LONG TERM...BORGHOFF
AVIATION...JRB
AREA FORECAST DISCUSSION
NWS BILLINGS MT
936 AM MDT WED SEP 18 2013
.UPDATE...
UPPER LOW CONTINUES TO APPROACH OUR REGION FROM THE WEST. 95KT H3
JET CURRENTLY LIFTING FROM SE ID INTO NW WY IS PROVIDING UPPER
SUPPORT...AND LINE OF SHOWERS WITH EMBEDDED TSTMS HAS FORMED ALONG
SFC FRONT IN SOUTH CENTRAL MT AND IS NEAR A 3HT TO LVM LINE AS OF
1530Z...MOVING SLOWLY EAST. HIGHWAY 212 HAS BEEN CLOSED OVER
BEARTOOTH PASS PER SOME WET SNOW OVER 9KFT OR SO. FISHER CK SNOTEL
AT 9100 FEET IS CURRENTLY 36F.
FORECAST IS ON TRACK AND HAVE MADE NO SIGNIFICANT CHANGES THIS
MORNING. EASTERN PARTS HAVE CLEARED SO HAVE REDUCED SKY COVER AND
POPS TIL 18Z...AND HAVE ALSO RAISED TEMPS A LITTLE PER THE SUN AND
WEST WINDS. MORNING DESTABILIZING SHOULD BE FOLLOWED BY SOME
STRONGER STORMS IN OUR EAST THIS AFTERNOON AS ASCENT INCREASES...
AND THIS INDEED IS WHAT THE LATEST HRRR IS HINTING AT. TSTMS WILL
BE MORE ISOLD WITH GENERALLY SHOWERY/COOLER WEATHER OUT WEST. 12Z
BOISE RAOB SHOWS 500MB OF -20C AND 700MB TEMP OF -5C...CONTINUING
THE TREND OF COLDER MID AND UPPER LEVEL TEMPS FURTHER SOUTH AS THE
TROF PUSHES THROUGH THE NORTHERN ROCKIES...AND THIS IS CONSISTENT
WITH A MORE AMPLIFIED UPPER JET. ALL THAT BEING SAID...SHOWER
ACTIVITY WILL CONTINUE THROUGH THE DAY AND INTO TONIGHT...WITH
SNOW LEVELS LIKELY TO DROP TO AROUND 8KFT. STRONGER DESCENT AND
LOW LEVEL DOWNSLOPE WINDS WILL REDUCE OUR PCPN CHANCES
SIGNIFICANTLY AFTER 00Z. HAVE RAISED WESTERN POPS THROUGH THE
AFTERNOON THOUGH BASED ON ASCENT...POST FRONTAL MOISTURE AND
COOLING ALOFT.
JKL
&&
.SHORT TERM...VALID FOR TDY AND THU...
PASSAGE OF THE LONG-ADVERTISED UPPER-LEVEL TROUGH IS STILL SET FOR
TODAY...BUT SOME UNCERTAINTY REMAINS IN PRECIPITATION COVERAGE. WE
HAVE MUCH MORE CONFIDENCE IN THE ARRIVAL OF COOL TEMPERATURES.
TODAY...FORCING FOR ASCENT SIMULATED BY MODEL 500-300 HPA Q-VECTOR
FIELDS IS BEING MANIFEST AS RAINFALL IN SOUTHEASTERN ID ALREADY AS
OF 09 UTC. WE EXPECT THAT VERTICAL MOTION AND PRECIPITATION TO GET
UP INTO SOUTH CENTRAL MT THIS MORNING...SO LIKELY POPS REMAIN FROM
COOKE CITY AND LIVINGSTON AND ALL THE WAY UP TO HARLOWTON. THAT IS
SUPPORTED BY ENSEMBLE OUTPUT INCLUDING THE 21 UTC SREF. CONFIDENCE
IS LOWER THAT ANYTHING MORE THAN SCATTERED SHOWERS WILL OCCUR EAST
OF THERE IN PLACES LIKE BILLINGS TODAY BECAUSE MODELS ALL SIMULATE
SUBSIDENCE FROM NEAR THE SURFACE TO 500 HPA...WITH DOWNSLOPE WINDS
AIDING THAT PROCESS BY AFTERNOON TOO. THE DOWNSLOPE SIGNATURE WILL
WEAKEN FROM BIG HORN COUNTY AND INTO SOUTHEASTERN MT...SO POPS ARE
HIGHER /IN THE 50 PERCENT RANGE/ THIS AFTERNOON IN THOSE AREAS. IT
LOOKS LIKE STORMS MAY ACTUALLY FIRE FROM BIG HORN COUNTY EAST OVER
INTO SOUTHEASTERN MT AFTER 18 UTC AS HEIGHT FALLS OCCUR ALOFT WITH
A MODERATELY UNSTABLE BOUNDARY LAYER. FORECAST SOUNDINGS IN PLACES
LIKE EKALAKA SHOW MLCAPE UP TO 800 J/KG AND 50 KT MID-LEVEL WINDS.
THUS...WE COULD ACTUALLY HAVE SOME STRONG STORMS OVER SOUTHEASTERN
MT THIS AFTERNOON AND EARLY EVENING. THAT IDEA IS SUPPORTED BY THE
00 UTC 4 KM WRF-NMM OUTPUT. OF COURSE...THAT BANKS ON SOME HEATING
OF THE BOUNDARY LAYER THAT IS NOT A GIVEN IF CLOUDS ARE TOO THICK.
IF CLOUDS DO NOT HINDER WARMING TOO MUCH...70S F ARE ATTAINABLE IN
SOUTHEASTERN MT. COLD AIR ADVECTION WILL BEGIN SOONER ACROSS SOUTH
CENTRAL MT...MAKING 60S F MORE COMMON THERE. ISOLATED THUNDERSTORM
WORDING IS STILL NEEDED EVEN WHERE IT WILL BE COOLER THOUGH DUE TO
SEASONABLY STEEP MID-LEVEL LAPSE RATES.
TONIGHT...WE HAVE AT LEAST LOW SHOWER CHANCES THIS EVENING FOR THE
ENTIRE AREA...AND LINGERING THUNDERSTORM CHANCES OVER SOUTHEASTERN
MT AS WELL. HOWEVER...A DRYING TREND WILL BE IN PLACE OVERNIGHT IN
MOST AREAS WITH ONLY WEAK LARGE-SCALE FORCING.
THU...COOL AND CYCLONIC LOW-LEVEL FLOW SHOULD YIELD QUITE A BIT IN
THE WAY OF STRATOCUMULUS CLOUD COVER ACROSS MOST OF THE AREA. THAT
WILL DO LITTLE TO HELP TEMPERATURES...WHICH SHOULD ONLY TOP OUT IN
THE 60S F IN THE LOWER ELEVATIONS. THE 00 UTC GUIDANCE ALL SHOWS A
MODEST SHORT WAVE TROUGH DROPPING INTO THE BACK SIDE OF THE LARGER
500-HPA TROUGH AND ACROSS SOUTHEASTERN MT DURING THE MORNING. THAT
SUPPORTS OUR PREVIOUSLY-ADVERTISED LOW SHOWER CHANCES IN THE MILES
CITY AND BAKER AREAS...BUT LATER FORECASTS MAY EVEN NEED A LOW POP
BEYOND 18 UTC FOR PARTS OF SOUTHEASTERN MT IF THE SHORT WAVE SLOWS
UP AT ALL. SCHULTZ
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
MODELS CONTINUE TO POINT TO A WARM AND DRY PERIOD FRIDAY THROUGH
SATURDAY AS AN AMPLIFIED RIDGE PREVAILS OVER THE ROCKIES AND HIGH
PLAINS. HOWEVER...ANOTHER TROUGH IS IN POSITION OVER THE PACIFIC
NORTHWEST BY SATURDAY EVENING TO INVADE THE NORTHERN ROCKIES. THIS
LOOKS LIKE A SPLIT FLOW TROUGH. AS SUCH...THE HIGH COUNTRY WILL
SEE THE BEST POPS WHILE LOWER ELEVATIONS SEE PRIMARILY WIND AS THE
TROUGH MOVES THROUGH SATURDAY NIGHT AND SUNDAY. AT THIS
TIME...THE MODEL PROGGS ARE IN PRETTY DECENT AGREEMENT THROUGH THE
WEEKEND. SO...CONFIDENCE IS ABOVE NORMAL IN THIS SOLUTION. STRONG
ZONAL FLOW SUNDAY NIGHT THROUGH MONDAY WILL KEEP THE LOWER
ELEVATIONS DRY AND BREEZY WHILE WEST FACING SLOPES OF THE
SOUTHWEST MOUNTAINS MAY SEE SOME BRIEF PRECIPITATION FROM ANY WEAK
SHORT WAVE IN THE WESTERLY FLOW.
AS WE HEAD TOWARD THE MIDDLE PART OF NEXT WEEK THE MODELS
INDICATE ANOTHER BROAD TROUGH DEVELOPING OVER THE WEST. HOW THIS
EVENTUALLY UNFOLDS HAS A GREAT DEAL OF UNCERTAINTY. THE ECMWF CUTS
OFF THE UPPER LOW AND MOVES IT THROUGH THE GREAT BASIN AND
CLOBBERS OUR FORECAST AREA...MAINLY IN THE MOUNTAINS...WITH WHAT
COULD BE A WINTER STORM. THE GFS ON THE OTHER HAND DIVES THE UPPER
LOW FURTHER SOUTH AND SLOWS IT DOWN KEEPING OUR REGION GENERALLY
DRY. BLENDED THE TWO FOR NOW LEANING A BIT TOWARD A DRIER SCENARIO
AS PREVIOUS TROUGHS UP TO THAT POINT LOOK TO BE SPLIT FLOWS...AND
THAT CAN OFTEN TIMES BECOME A PERSISTENT OCCURRENCE. THAT
SAID...MIDDLE OF NEXT WEEK MAY BE INTERESTING. BT
&&
.AVIATION...
UNSETTLED WEATHER CONDITIONS WILL CONTINUE OVER THE FORECAST AREA
TODAY. AREAS OF LIGHT TO MODERATE SHOWERS WITH EMBEDDED
THUNDESTORMS ARE EXPECTED IN THE EAST...AS WELL AS OVER THE HIGHER
TERRAIN AND NEARBY AREAS IN THE WEST. WESTERLY WINDS ARE EXPECTED
TO INCREASE WITH SUSTAINED SPEEDS 15 TO 25 KTS AFFECTING WESTERN
ROUTES BY 18Z AND SPREADING EAST THROUGH THE AFTERNOON. BT
&&
.PRELIMINARY POINT TEMP/POPS...
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 068 045/065 046/076 047/082 053/068 048/071 051/071
5/T 20/B 00/U 00/U 12/T 10/B 01/B
LVM 060 038/066 038/077 041/081 046/065 042/068 046/068
7/T 20/B 00/U 00/U 22/T 11/B 12/W
HDN 073 046/067 041/078 047/085 051/072 046/073 050/074
5/T 21/B 00/U 00/U 12/T 10/B 01/B
MLS 075 048/065 044/075 048/084 054/073 050/075 053/074
5/T 32/W 00/U 00/U 12/T 10/U 01/B
4BQ 077 047/064 041/075 045/082 053/075 047/074 050/075
5/T 31/B 00/U 00/U 12/T 20/U 01/U
BHK 078 048/063 038/071 044/079 050/075 047/073 049/074
4/T 32/W 00/U 00/U 02/T 20/U 01/U
SHR 074 043/063 038/076 044/083 050/070 044/071 048/072
4/T 21/B 00/U 00/U 12/T 20/U 01/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
942 AM CDT WED SEP 18 2013
.UPDATE...
ISSUED AT 936 AM CDT WED SEP 18 2013
CHANGES THIS UPDATE PERIOD WERE TO EXTEND/EXPAND LOW POPS ACROSS
CENTRAL PORTIONS OF FA AS CONVECTION HOLDING TOGETHER AS IT
PROPAGATES ENE INTO CENTRAL/NORTHERN FA. ACTUALLY SEEING A FEW LTG
STRIKES SO MENTIONED THUNDER FOR THE REMAINDER OF THE AM. WITH LOW
CIGS FOG HOLDING ON A LITTLE LONGER BUT SHOULD CONTINUE TO
IMPROVE. WILL ADDRESS CLOUD TRENDS AND TEMPERATURES NEXT UPDATE.
UPDATE ISSUED AT 714 AM CDT WED SEP 18 2013
EXPANDED 20 POPS ACROSS THE FAR WESTERN FORECAST AREA FROM 12 TO
15 UTC THIS MORNING TO ACCOUNT FOR BAND OF LIGHT SHOWERS FROM
HARVEY TO EDGELEY...MOVING TO THE EAST-NORTHEAST AROUND 25 MPH.
HRRR SUGGESTS THIS ACTIVITY SHOULD DISSIPATE AS IT PROPAGATES
EAST. OTHERWISE...MADE SOME MINOR ADJUSTMENTS TO CLOUD COVER.
REST OF THE FORECAST IN GOOD SHAPE.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013
CHALLENGES INCLUDE CLOUD COVER AND TEMPERATURES THROUGH THE DAY
AND THEN CONVECTIVE CHANCES AND SEVERE POTENTIAL THIS EVENING
THROUGH THURSDAY. DESPITE DIFFERING QPF AMOUNTS AND LOCATIONS...
GFS/NAM/ECMWF ARE IN GOOD OVERALL AGREEMENT WITH SURFACE LOW TRACK.
THE GEM IS AN OUTLIER AND WILL NOT BE CONSIDERED WITH THIS FORECAST.
FOCUSED ON THE RAP FOR NEAR TERM CLOUD/TEMPERATURE TRENDS.
LOW CLOUDS HAVE ONCE AGAIN ENVELOPED THE ENTIRE FORECAST AREA AND
EXPECT A VERY SLOW EROSION FROM SOUTHWEST TO NORTHEAST THROUGH THE
DAY DUE TO MOIST SOUTH-SOUTHEAST FLOW AND A STRONG MID-LEVEL
INVERSION. RAP 925 HPA RH SUGGESTS THE SUN SHOULD BEGIN TO MAKE AN
APPEARANCE ACROSS SOUTHEAST ND INTO THE DEVILS LAKE BASIN BY EARLY
AFTERNOON...BUT MUCH OF NORTHEAST ND INTO NORTHWEST MN WILL REMAIN
CLOUDY THROUGH THE DAY. WITH INCREASED CLOUD COVER...DROPPED
HIGH TEMPERATURES 3 TO 5 DEGREES. THIS MAY STILL NOT BE ENOUGH
NOTING YESTERDAY/S SLOW RECOVERY. AS A RESULT...SOME AREAS ACROSS
THE NORTH MAY NOT TOP 70 DEGREES. OTHERWISE...HIGHS WILL RANGE
FROM THE LOW 70S ACROSS THE NORTH TO THE LOW 80S ACROSS THE SOUTH.
ADDED SOME SLIGHT CHANCE POPS TO THE DEVILS LAKE BASIN THIS MORNING
TO ACCOUNT FOR WEAKENING ECHOES CURRENTLY ACROSS THE WESTERN HALF
OF ND. OTHERWISE...MOST OF THE DAY SHOULD BE DRY GIVEN A STRONG
CAP AND DELAYED DYNAMIC SUPPORT. REMOVED POPS THROUGH 21 UTC...
INCREASING TO HIGH CHANCES FROM WEST TO EAST THEREAFTER.
SURFACE LOW WILL TRACK ALONG THE ND/SD BORDER WITH A WARM FRONT
EXTENDING TO THE EAST AND INTO WEST CENTRAL MN. CLEARING SKIES
LATE THIS AFTERNOON WILL HELP REALIZE 2000 TO 3000 J/KG OF
INSTABILITY AND WITH PWATS INCREASING TO 1.5 INCHES AND THE
APPROACHING WARM FRONT...EXPECT SCATTERED CONVECTIVE DEVELOPMENT
INITIALLY ACROSS THE SOUTHERN FORECAST AREA. SHOWERS AND
THUNDERSTORMS SHOULD EXPAND NORTHWARD THROUGH THE EVENING WITH THE
APPROACHING COLD FRONT AND STRONG FORCING ALOFT. SPC DAY ONE
CONVECTIVE OUTLOOK HAS EXPANDED ITS SLIGHT RISK TO INCLUDE ALMOST
ALL OF EASTERN ND AND PORTIONS OF NORTHWEST MN. SOME STORMS MAY
BECOME STRONG TO SEVERE WITH THE PRIMARY THREATS BEING LARGE HAIL
AND DAMAGING WIND...BUT CANNOT RULE OUT A TORNADO OR TWO...
ESPECIALLY NEAR FRONTAL BOUNDARIES.
THUNDERSTORMS THAT DEVELOP WILL MOVE EASTWARD AHEAD OF THE ADVANCING
COLD FRONT AND SHOULD EXIT THE FORECAST AREA BY NOON ON THURSDAY.
BREEZY NORTHWEST WIND WILL FOLLOW FRONTAL PASSAGE WITH COOLING
TEMPERATURES. HIGHS THURSDAY WILL RANGE FROM THE LOWER 60S ACROSS
THE NORTHWEST TO THE LOWER 70S ACROSS THE SOUTHEAST.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013
WITH THE EXCEPTION OF SOME LINGERING WRAP-AROUND SHOWERS ACROSS
THE LAKE OF THE WOODS REGION...FRIDAY WILL BE PARTLY SUNNY AND DRY
AS SURFACE HIGH PRESSURE BUILDS ACROSS THE NATION/S MID-SECTION.
BREEZY NORTHWEST WIND WILL PERSIST AND TEMPERATURES WILL TOP OUT
IN THE LOWER TO MID 60S REGION-WIDE.
SATURDAY-TUESDAY...00Z MODELS APPEAR STABLE RUN TO RUN AND CONFIDENCE
IS SLIGHTLY BETTER THAN AVERAGE. PERIOD BEGINS WITH RIDGING ALOFT...
WITH SOUTHWEST FLOW DEVELOPING BY THE END OF THE WEEKEND. THE
STRONGEST SIGNAL FOR PRECIP APPEARS TO BE MONDAY-MONDAY NIGHT.
SOUTHWEST FLOW ALOFT CONTINUES INTO TUESDAY...ALTHOUGH THERE IS NO
CLEAR SIGNAL FOR PRECIP. TEMPERATURES WILL BEGIN NEAR NORMAL...AND
TRANSITION TO SLIGHTLY ABOVE NORMAL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 714 AM CDT WED SEP 18 2013
IFR/MVFR CLOUD DECK WILL BE VERY SLOW TO DISSIPATE TODAY GIVEN
MOIST SOUTHERLY FLOW AND A STRONG MID-LEVEL INVERSION. EXPECT
CEILINGS TO DISSIPATE AND LIFT FROM SOUTHWEST TO NORTHEAST
BEGINNING EARLY-MID AFTERNOON. SHOWERS AND THUNDERSTORMS WILL
DEVELOP LATE THIS AFTERNOON AND EVENING AND MOVE EASTWARD
OVERNIGHT AS A STRONG COLD FRONT SWEEPS ACROSS THE DAKOTAS...
BUT GIVEN TIMING AND COVERAGE UNCERTAINTY...WILL COVER THE THREAT
WITH VCTS FOR 12 UTC TAFS. SOUTH-SOUTHEAST WIND AHEAD OF THE FRONT
WILL SHIFT TO THE WEST-NORTHWEST AFTER FRONTAL PASSAGE WITH GUSTS
UP TO 20 KTS POSSIBLE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...VOELKER
SHORT TERM...ROGERS
LONG TERM...ROGERS/TG
AVIATION...ROGERS
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
714 AM CDT WED SEP 18 2013
.UPDATE...
ISSUED AT 714 AM CDT WED SEP 18 2013
EXPANDED 20 POPS ACROSS THE FAR WESTERN FORECAST AREA FROM 12 TO
15 UTC THIS MORNING TO ACCOUNT FOR BAND OF LIGHT SHOWERS FROM
HARVEY TO EDGELEY...MOVING TO THE EAST-NORTHEAST AROUND 25 MPH.
HRRR SUGGESTS THIS ACTIVITY SHOULD DISSIPATE AS IT PROPAGATES
EAST. OTHERWISE...MADE SOME MINOR ADJUSTMENTS TO CLOUD COVER.
REST OF THE FORECAST IN GOOD SHAPE.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013
CHALLENGES INCLUDE CLOUD COVER AND TEMPERATURES THROUGH THE DAY
AND THEN CONVECTIVE CHANCES AND SEVERE POTENTIAL THIS EVENING
THROUGH THURSDAY. DESPITE DIFFERING QPF AMOUNTS AND LOCATIONS...
GFS/NAM/ECMWF ARE IN GOOD OVERALL AGREEMENT WITH SURFACE LOW TRACK.
THE GEM IS AN OUTLIER AND WILL NOT BE CONSIDERED WITH THIS FORECAST.
FOCUSED ON THE RAP FOR NEAR TERM CLOUD/TEMPERATURE TRENDS.
LOW CLOUDS HAVE ONCE AGAIN ENVELOPED THE ENTIRE FORECAST AREA AND
EXPECT A VERY SLOW EROSION FROM SOUTHWEST TO NORTHEAST THROUGH THE
DAY DUE TO MOIST SOUTH-SOUTHEAST FLOW AND A STRONG MID-LEVEL
INVERSION. RAP 925 HPA RH SUGGESTS THE SUN SHOULD BEGIN TO MAKE AN
APPEARANCE ACROSS SOUTHEAST ND INTO THE DEVILS LAKE BASIN BY EARLY
AFTERNOON...BUT MUCH OF NORTHEAST ND INTO NORTHWEST MN WILL REMAIN
CLOUDY THROUGH THE DAY. WITH INCREASED CLOUD COVER...DROPPED
HIGH TEMPERATURES 3 TO 5 DEGREES. THIS MAY STILL NOT BE ENOUGH
NOTING YESTERDAY/S SLOW RECOVERY. AS A RESULT...SOME AREAS ACROSS
THE NORTH MAY NOT TOP 70 DEGREES. OTHERWISE...HIGHS WILL RANGE
FROM THE LOW 70S ACROSS THE NORTH TO THE LOW 80S ACROSS THE SOUTH.
ADDED SOME SLIGHT CHANCE POPS TO THE DEVILS LAKE BASIN THIS MORNING
TO ACCOUNT FOR WEAKENING ECHOES CURRENTLY ACROSS THE WESTERN HALF
OF ND. OTHERWISE...MOST OF THE DAY SHOULD BE DRY GIVEN A STRONG
CAP AND DELAYED DYNAMIC SUPPORT. REMOVED POPS THROUGH 21 UTC...
INCREASING TO HIGH CHANCES FROM WEST TO EAST THEREAFTER.
SURFACE LOW WILL TRACK ALONG THE ND/SD BORDER WITH A WARM FRONT
EXTENDING TO THE EAST AND INTO WEST CENTRAL MN. CLEARING SKIES
LATE THIS AFTERNOON WILL HELP REALIZE 2000 TO 3000 J/KG OF
INSTABILITY AND WITH PWATS INCREASING TO 1.5 INCHES AND THE
APPROACHING WARM FRONT...EXPECT SCATTERED CONVECTIVE DEVELOPMENT
INITIALLY ACROSS THE SOUTHERN FORECAST AREA. SHOWERS AND
THUNDERSTORMS SHOULD EXPAND NORTHWARD THROUGH THE EVENING WITH THE
APPROACHING COLD FRONT AND STRONG FORCING ALOFT. SPC DAY ONE
CONVECTIVE OUTLOOK HAS EXPANDED ITS SLIGHT RISK TO INCLUDE ALMOST
ALL OF EASTERN ND AND PORTIONS OF NORTHWEST MN. SOME STORMS MAY
BECOME STRONG TO SEVERE WITH THE PRIMARY THREATS BEING LARGE HAIL
AND DAMAGING WIND...BUT CANNOT RULE OUT A TORNADO OR TWO...
ESPECIALLY NEAR FRONTAL BOUNDARIES.
THUNDERSTORMS THAT DEVELOP WILL MOVE EASTWARD AHEAD OF THE ADVANCING
COLD FRONT AND SHOULD EXIT THE FORECAST AREA BY NOON ON THURSDAY.
BREEZY NORTHWEST WIND WILL FOLLOW FRONTAL PASSAGE WITH COOLING
TEMPERATURES. HIGHS THURSDAY WILL RANGE FROM THE LOWER 60S ACROSS
THE NORTHWEST TO THE LOWER 70S ACROSS THE SOUTHEAST.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013
WITH THE EXCEPTION OF SOME LINGERING WRAP-AROUND SHOWERS ACROSS
THE LAKE OF THE WOODS REGION...FRIDAY WILL BE PARTLY SUNNY AND DRY
AS SURFACE HIGH PRESSURE BUILDS ACROSS THE NATION/S MID-SECTION.
BREEZY NORTHWEST WIND WILL PERSIST AND TEMPERATURES WILL TOP OUT
IN THE LOWER TO MID 60S REGION-WIDE.
SATURDAY-TUESDAY...00Z MODELS APPEAR STABLE RUN TO RUN AND CONFIDENCE
IS SLIGHTLY BETTER THAN AVERAGE. PERIOD BEGINS WITH RIDGING ALOFT...
WITH SOUTHWEST FLOW DEVELOPING BY THE END OF THE WEEKEND. THE
STRONGEST SIGNAL FOR PRECIP APPEARS TO BE MONDAY-MONDAY NIGHT.
SOUTHWEST FLOW ALOFT CONTINUES INTO TUESDAY...ALTHOUGH THERE IS NO
CLEAR SIGNAL FOR PRECIP. TEMPERATURES WILL BEGIN NEAR NORMAL...AND
TRANSITION TO SLIGHTLY ABOVE NORMAL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 714 AM CDT WED SEP 18 2013
IFR/MVFR CLOUD DECK WILL BE VERY SLOW TO DISSIPATE TODAY GIVEN
MOIST SOUTHERLY FLOW AND A STRONG MID-LEVEL INVERSION. EXPECT
CEILINGS TO DISSIPATE AND LIFT FROM SOUTHWEST TO NORTHEAST
BEGINNING EARLY-MID AFTERNOON. SHOWERS AND THUNDERSTORMS WILL
DEVELOP LATE THIS AFTERNOON AND EVENING AND MOVE EASTWARD
OVERNIGHT AS A STRONG COLD FRONT SWEEPS ACROSS THE DAKOTAS...
BUT GIVEN TIMING AND COVERAGE UNCERTAINTY...WILL COVER THE THREAT
WITH VCTS FOR 12 UTC TAFS. SOUTH-SOUTHEAST WIND AHEAD OF THE FRONT
WILL SHIFT TO THE WEST-NORTHWEST AFTER FRONTAL PASSAGE WITH GUSTS
UP TO 20 KTS POSSIBLE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...ROGERS
SHORT TERM...ROGERS
LONG TERM...ROGERS/TG
AVIATION...ROGERS
AREA FORECAST DISCUSSION
NWS TULSA OK
1030 AM CDT WED SEP 18 2013
.DISCUSSION...
FESTERING AREAS OF LIGHT RAIN/SPRINKLES ACROSS THE AREA THIS
MORNING. HOURLY HRRR OUTPUT MAINTAINS CONSISTENCY BY KEEPING THIS
ACTIVITY ONGOING WELL INTO THE AFTERNOON. WILL MAINTAIN THUNDER
CHANCES ACROSS THE EAST THIS AFTERNOON...AND ACROSS THE WEST WILL
CARRY SPRINKLES INTO MID AFTERNOON. PERSISTENT CLOUD COVER WILL
HAMPER AFTERNOON MAX TEMPS...SO HAVE LOWERED ADVERTISED HIGHS
EVERYWHERE. REST OF FORECAST BEYOND FIRST PERIOD LEFT AS IS.
UPDATED ZFP/PFM/AFM OUT SHORTLY.
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
SHORT TERM...23
LONG TERM....21
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
608 AM CDT WED SEP 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 248 AM CDT WED SEP 18 2013
MAIN FORECAST CONCERNS IN THE SHORT TERM ARE ON SHOWER CHANCES THIS
MORNING AND TEMPERATURES THIS AFTERNOON.
LATEST WATER VAPOR IMAGERY SHOWED A TWO SHORTWAVES MOVING ACROSS THE
WESTERN GREAT LAKES INTO THE UPPER MISSISSIPPI RIVER VALLEY. THE
FIRST WAVE WAS PUSHING ACROSS EASTERN WISCONSIN/ILLINOIS...WHILE THE
SECOND AS MOVING ACROSS SOUTHERN MINNESOTA/NORTHERN IOWA. A BROAD
TROUGH WAS NOTED OVER THE PACIFIC NORTHWEST INTO THE ROCKIES WITH
SEVERAL EMBEDDED SHORTWAVES NOTED. SURFACE OBSERVATIONS SHOWED SURFACE
LOW PRESSURE DEVELOPING OVER THE WESTERN DAKOTAS...WITH A WARM FRONT
EXTENDING SOUTHEAST ACROSS EASTERN SOUTH DAKOTA THROUGH WESTERN IOWA
INTO CENTRAL MISSOURI.
SHOWERS AND ISOLATED THUNDERSTORMS...WILL PERSIST ACROSS THE AREA
THIS MORNING. THIS ACTIVITY SHOULD THEN GRADUALLY LIFT NORTH LATE
THIS MORNING INTO THIS AFTERNOON AS THE WARM FRONT LIFTS NORTH
ACROSS THE UPPER MISSISSIPPI RIVER VALLEY. THE STRATUS WILL ALSO
LIFT NORTH WITH THE WARM FRONT GIVING WAY TO PARTLY SUNNY SKIES BY
LATE AFTERNOON. THE STRATUS SHOULD START TO BREAK UP BY EARLY
AFTERNOON OVER SOUTHEAST MINNESOTA AND NORTHEAST IOWA. CLOUDS LOOK
TO HANG ON UNTIL LATE AFTERNOON OVER WESTERN INTO CENTRAL
WISCONSIN. THE CLOUD COVER WILL HAVE A BIG IMPACT ON HIGH
TEMPERATURES TODAY. AREAS THAT SEE CLEARING EARLIER THIS AFTERNOON
WEST OF THE MISSISSIPPI RIVER CAN EXPECT HIGHS IN THE LOWER TO MID
80S. LOCATIONS OVER WESTERN INTO CENTRAL WISCONSIN WILL LIKELY
STRUGGLE TO GET OUT OF THE 70S...WITH EVEN COOLER TEMPERATURES
POSSIBLE OVER NORTH CENTRAL WISCONSIN WHERE THEY COULD BE IN THE
CLOUD COVER THE ENTIRE DAY. DEWPOINTS CLIMB INTO THE MID 60S THIS
AFTERNOON IN THE WAKE OF THE WARM FRONT WITH MLCAPE VALUES
CLIMBING INTO THE 1100 TO 1500 J/KG RANGE RIGHT ALONG AND WEST OF
THE MISSISSIPPI BY LATE AFTERNOON. NOT EXPECTING MUCH IF ANY
SHOWER OR THUNDERSTORM ACTIVITY IN THE WAKE OF THE WARM FRONT AS
WEAK UPPER RIDGING ATTEMPTS TO BUILD INTO THE REGION. 850 MB
MOISTURE TRANSPORT REALLY RAMPS UP LATE TONIGHT INTO EARLY
THURSDAY MORNING AHEAD OF A COLD FRONT AND VIGOROUS UPPER LEVEL
TROUGH APPROACHING FROM THE PLAINS. NOT SEEING MUCH SUPPORT FOR
SHOWERS OR STORMS WITH HEIGHT RISES NOTED OVER THE REGION AT 500
MB EARLY IN THE NIGHT. FLOW ALOFT TURNS SOUTHWEST LATE TONIGHT
INTO EARLY THURSDAY MORNING AS A TROUGH DIGS INTO THE WESTERN
DAKOTAS. WE START TO LOSE THE RIDGING ALOFT LATE TONIGHT SO WOULD
EXPECT SOME SHOWER AND THUNDERSTORM DEVELOPMENT LATE.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 248 AM CDT WED SEP 18 2013
MAIN FORECAST CONCERNS IN THE LONG TERM ARE ON SHOWER AND
THUNDERSTORM CHANCES ON THURSDAY INTO THURSDAY NIGHT...WITH THE
POTENTIAL FOR A FEW STRONG TO POSSIBLY SEVERE STORMS.
A COLD FRONT WILL PUSH INTO WESTERN MINNESOTA EARLY THURSDAY MORNING
AND WILL CONTINUE DRIVING EASTWARD ACROSS THE UPPER MISSISSIPPI
RIVER VALLEY THROUGH THE DAY ON THURSDAY INTO THURSDAY EVENING.
MEANWHILE...AN UPPER TROUGH WILL MOVE EAST OUT OF THE
CENTRAL/NORTHERN PLAINS. A MOIST AND UNSTABLE AIRMASS WILL BE IN
PLACE ACROSS THE FORECAST AREA AS THE FRONT MOVES IN. SHOWERS AND
STORMS ARE EXPECTED AHEAD OF AND ALONG THE FRONT ON THURSDAY. IF THE
STORMS HOLD OFF UNTIL THE AFTERNOON HOURS AND CAN DEVELOP RIGHT
ALONG THE FRONT...THERE WOULD BE THE POTENTIAL FOR A FEW STRONG TO
PERHAPS SEVERE THUNDERSTORMS. DEEP LAYER SHEAR IS LAGGING WELL
BEHIND THE FRONT...WITH THE UPPER JET POSITIONED WELL OFF TO THE
WEST. 0-6 KM BULK SHEAR VALUES ARE RATHER WEAK...IN THE 20 TO 25 KT
RANGE. HOWEVER...THE SHEAR DOES INCREASE BY LATE AFTERNOON AS THE
UPPER TROUGH ATTEMPTS TO CATCH UP TO THE FRONT. 0-6 KM BULK SHEAR
VALUES INCREASE SLIGHTLY TO AROUND 30 KTS BY LATE AFTERNOON...AND
MOST OF THIS SHEAR IS FOCUSED IN THE 0-3 KM LAYER. THINKING THE MAIN
HAZARDS FROM ANY STRONGER STORMS WOULD BE GUSTY WINDS AND POSSIBLY
SOME LARGE HAIL. THIS SHEAR INCREASE LOOKS TO OCCUR OVER WESTERN
INTO CENTRAL WISCONSIN SO THINKING THESE AREAS WOULD HAVE SLIGHTLY
HIGHER POTENTIAL AT SEEING SOME STRONGER STORMS. THE OVERALL SEVERE
THREAT LOOKS LOW AT THIS TIME...UNLESS STORMS HOLD OFF UNTIL LATER
IN THE AFTERNOON. THE FRONT SHIFTS EAST OF THE AREA FRIDAY MORNING
BUT THE UPPER TROUGH MOVES THROUGH DURING THE AFTERNOON HOURS.
LATEST GUIDANCE CONTINUES TO BE A LITTLE SLOWER WITH THE
PRECIPITATION EXITING THE AREA ON FRIDAY SO WE COULD SEE SOME
SHOWERS AND STORMS LINGER OVER CENTRAL AND SOUTHWEST WISCONSIN INTO
EXTREME NORTHEAST IOWA.
CLOUDS SHOULD GRADUALLY DECREASE FROM WEST TO EAST ACROSS THE AREA
FRIDAY AFTERNOON AS THE UPPER TROUGH SWINGS THROUGH AND HIGH
PRESSURE BUILDS IN FRIDAY AFTERNOON INTO FRIDAY NIGHT. HIGH PRESSURE
WILL THEN BE THE DOMINATE WEATHER FEATURE FROM FRIDAY NIGHT THROUGH
THE WEEKEND. A VERY PLEASANT WEEKEND ON TAP FOR THE REGION WITH
HIGHS IN THE 60S ON SATURDAY...THEN WARMING SLIGHTLY INTO THE UPPER
60S TO LOWER 70S ON SUNDAY. THERE IS THE POTENTIAL FOR SOME FROST
THIS WEEKEND OVER CENTRAL INTO NORTH CENTRAL WISCONSIN. LATE
SATURDAY NIGHT INTO EARLY SUNDAY MORNING LOOKS LIKE THE MOST
FAVORABLE TIMEFRAME FOR FROST WHEN TEMPERATURES DROP INTO THE MID
30S. RAIN CHANCES RETURN MONDAY INTO TUESDAY AS ANOTHER TROUGH MOVES
THROUGH THE REGION.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 608 AM CDT WED SEP 18 2013
LINE OF THUNDERSTORMS IS MOVING NORTHEAST OUT OF NORTH CENTRAL
IOWA AND IS FILLING IN/EXPANDING TO THE NORTH ACROSS SOUTHERN
MINNESOTA. AT THIS TIME...REGIONAL RADARS SHOWING THIS TO BE THE
LAST OF THE CONVECTIVE ACTIVITY TO MOVE THROUGH THIS MORNING AND
THIS IS ALSO THE TREND SHOWN IN THE 18.09Z HRRR. BASED THE PRESENT
MOVEMENT OF THIS LINE...WILL SHOW A 2 HOUR WINDOW OF TSRA AT KRST
RIGHT FROM THE START OF THE TAF AND THEN AROUND 14Z AT KLSE. AFTER
THAT THE PROBLEM BECOMES HOW LONG THE IFR CONDITIONS WILL STICK
AROUND. LOOKING AT THE 18.09Z RAP BUFKIT SOUNDINGS...NOT EXPECTING
THESE TO BEGIN LIFTING UNTIL LATE MORNING WITH KRST NOT BECOMING
MVFR UNTIL EARLY AFTERNOON. DRIER AIR SHOULD THEN START MIXING IN
TO ACTUALLY ALLOW BOTH SITES TO SCATTER OUT BY MID TO LATE
AFTERNOON. DESPITE THE RECENT RAINS...SHOULD BE ENOUGH WIND
OVERNIGHT TO PREVENT FOG FROM FORMING. A COLD FRONT WILL START TO
APPROACH FROM THE WEST OVERNIGHT. SOME ADDITIONAL SCATTERED
CONVECTION COULD DEVELOP LATE TONIGHT OUT AHEAD OF THE FRONT BUT
CONFIDENCE ON THIS IS TOO LOW TO INCLUDE IN THE FORECAST AT THIS
TIME.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...04
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
516 PM CDT WED SEP 18 2013
.DISCUSSION...
336 PM CDT
MAIN CHALLENGES/CONCERNS THIS FORECAST PERIOD ARE WITH SHOWERS AND
THUNDERSTORMS IN THE NEAR TERM...POSSIBLE PERSISTENT
SHOWERS/THUNDERSTORMS OVERNIGHT...AS WELL AS BETTER CHANCES FOR
SHOWERS/THUNDERSTORMS THURSDAY NIGHT INTO FRIDAY MORNING.
CONTINUE TO MONITOR AREA OF SHOWERS AND THUNDERSTORMS ACROSS NORTH
CENTRAL ILLINOIS THAT HAVE CONTINUED TO SLOWLY MOVE EAST TODAY.
LATEST RADAR IMAGERY DEPICTING A CONTINUED DEVELOPING TREND IN
BOTH COVERAGE AND INTENSITY WITH THIS AREA OF PRECIPITATION...AND
EXPECT THIS TO CONTINUE THROUGH THE AFTERNOON AND EARLY EVENING.
MCV IS THE MAIN DRIVING FORCE FOR THESE
SHOWERS/THUNDERSTORMS...WITH LATEST RAP ANALYSIS SHOWING LOWERING
CIN AND AN AXIS OF 1000 J/KG OF SB CAPE EXTENDING INTO NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH NOT THE GREATEST...THESE
CONDITIONS WILL BE ENOUGH TO HELP THIS PRECIP TO HOLD TOGETHER
WHILE IT SLOWLY MOVES THROUGH NORTHEAST ILLINOIS THIS AFTERNOON
AND THEN NORTHWEST INDIANA THROUGH EARLY EVENING. ALTHOUGH
WIDESPREAD SEVERE WEATHER IS NOT ANTICIPATED...A PORTION OF THESE
STORMS ALONG THE I-80 CORRIDOR HAVE EXHIBITED SOME STRENGTHENING
TRENDS WITH BRIEF HIGHER WIND SIGNATURES. SO FOR THIS
AFTERNOON/EARLY EVENING...EXPECT ANY OF THE STRONGER STORMS IN
THIS GENERAL AREA TO BE CAPABLE OF PRODUCING SPORADIC WIND GUSTS
TO 50 MPH...CONTINUOUS LIGHTNING...AND BRIEF HEAVY RAINFALL WITH
AN OUTSIDE POSSIBILITY OF AN ISOLATED SEVERE WIND THREAT.
WITH THE DEPARTURE OF THESE THUNDERSTORMS...MOST OF THE CWA SHOULD
OBSERVE A LULL IN PRECIP BEFORE SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE ONCE AGAIN OVER NIGHT. SEVERAL WEAK MID LEVEL FEATURES
WILL CONTINUE TO TRAVERSE CURRENT ZONAL FLOW OVERHEAD...WITH
LOW/MID LEVEL FLOW VEERING OVERNIGHT. AS THIS OCCURS...IT APPEARS
AS BETTER WAA WILL ORIENT ITSELF MORE TOWARDS NORTHERN ILLINOIS.
ALTHOUGH CONFIDENCE IS NOT THE GREATEST FOR COVERAGE TONIGHT...DID
MAINTAIN LOW CHANCE POPS FOR MOST AREAS MAINLY AFTER MIDNIGHT
OWING TO THIS POTENTIAL. WHATEVER DOES DEVELOP SHOULD BE MORE
SCATTERED IN NATURE...AND THEN BEGIN SHIFTING EAST OUT OF THE CWA
WHILE DIMINISHING EARLY THURSDAY MORNING. WITH BROAD SOUTHWESTERLY
FLOW PERSISTING ON THURSDAY AND A FAIRLY MOIST ENVIRONMENT
OVERHEAD...SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE.
ALTHOUGH...CHANCES FOR PRECIPITATION SHOULD REMAIN LOW WITH ONCE
AGAIN ANYTHING THAT DOES DEVELOP REMAINING SCATTERED. WITH THIS
PERSISTENT WAA...CONTINUED WARMUP WILL CONTINUE ON THURSDAY. MADE
LITTLE ADJUSTMENTS TO MAX TEMPS FOR THURSDAY KEEPING UPPER 80S FOR
MOST LOCATIONS...WITH SOME UNCERTAINTIES TO PRECIP AND EVEN CLOUD
COVER REMAINING. IF ENOUGH CLEARING OCCURS...THERMO PROFILES WILL
BE SUPPORTIVE OF SOME LOCATIONS REACHING OR SLIGHTLY EXCEEDING 90
DEGREES.
MAIN FOCUS FOR THUNDERSTORM DEVELOPMENT SHIFTS TOWARDS THE LATE
AFTERNOON AND EARLY EVENING WITH AN APPROACHING TROUGH OF LOW
PRESSURE AND COLD FRONT. AS LARGE VORT MAX DROPS SOUTHEAST ACROSS
THE NORTHERN PLAINS...SEVERAL WAVES OF ENERGY WILL LIFT NORTHEAST
ACROSS THE REGION. THIS WILL HELP TO SHIFT THIS TROUGH/FRONT AS WELL
AS INDUCING SOME FURTHER PRESSURE FALLS OUT AHEAD OF IT. WITH
POTENTIAL FOR PRE FRONTAL TROUGHINESS TO OCCUR TOMORROW
AFTERNOON...SOME GUIDANCE CONTINUES TO DEVELOP PRECIP OUT AHEAD OF
THIS FRONT. ALTHOUGH I FEEL THIS IS A BIT OVERDONE...AND HAVE HELD
BACK ON POPS FOR THURSDAY DURING THE DAY. HAVE EVEN TRENDED
TOWARDS A SLOWER SOLUTION/TREND WITH THIS FRONT/TROUGH WITH BEST
CHANCES FOR SHOWERS/THUNDERSTORMS REMAINING OVER WEST/NORTHWEST
ILLINOIS FOR MOST OF THURSDAY NIGHT. ITS NOT UNTIL EARLY FRIDAY
MORNING THAT THIS FRONT GETS A GOOD SOUTHEAST PUSH WITH BEST
FORCING MOVING OVERHEAD. GOOD SWATH OF PRECIP SHOULD SHIFT
SOUTHEAST ACROSS THE ENTIRE CWA THROUGH MID DAY FRIDAY...WITH THIS
PRECIP THEN EXPECTED TO SHIFT OUT OF THE AREA THROUGH THE
AFTERNOON. IT DOES APPEAR AS IF THE STRONGER STORMS SHOULD REMAIN
JUST WEST OF THE CWA...BUT WITH SOME POTENTIAL FOR THEM TO REACH
THE FAR WESTERN CWA THURSDAY EVENING/NIGHT. IF INSTABILITY CAN
INCREASE ON FRIDAY...THERE IS THE POTENTIAL FOR A LINGERING STRONG
TO SEVERE THREAT ACROSS THE CWA BEFORE THE STORMS SHIFT OUT OF THE
CWA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* SCT SHRA AND A FEW ISOLATED TSRA EXPECTED THROUGH 23 TO 00 UTC
THIS EVENING.
* LOW CHANCE FOR ADDITIONAL SHRA/TSRA THURSDAY MORNING.
MDB/KB
//DISCUSSION...UPDATED 22Z...
A FEW ADDITIONAL SHOWERS AND ISOLATED THUNDERSTORMS HAVE DEVELOPED
ACROSS SOUTHERN MCHENRY AND FAR NORTHERN KANE COUNTIES OVER THE
PAST HOUR. THESE APPEAR TO BE ASSOCIATED WITH THE MAIN MID LEVEL
CIRCULATION MOVING ACROSS FAR NORTHERN ILLINOIS. CONFIDENCE ON IF
THESE STORMS WILL DIRECTLY MOVE ACROSS KORD IS LOW AT THIS
TIME...BUT IF THEY MAINTAIN THEMSELVES THEY COULD MOVE OVER KORD
SHORTLY AFTER 23 UTC. I WILL WATCH THESE CLOSELY TO SEE IF TSRA
NEEDS TO BE ADDED TO KORD FOR A SHORT PERIOD.
//DISCUSSION...UPDATED 20Z...
TSRA SITUATION HAS EVOLVED OVER THE LAST 2 HOURS. LOW LEVEL
CIRCULATION HAS CONTINUED TO DEVELOP AND HAS FOCUSED DEVELOPMENT
TO ITS SOUTHEAST LEADING TO HIGHER TSRA COVERAGE FROM DKB
SOUTHWESTWARD...WITH THE EARLIER AREA OF CONVECTION TO THE NORTH
SLOWLY FADING. BASED ON THESE TRENDS HAVE SPED UP TIMING OF TSRA
IN THE CHI AREA TAFS AND ADDED TSRA TO GYY. NEW ACTIVITY IS MOVING
A BIT MORE QUICKLY SO IT APPEARS THAT IT MAY BE CLEAR OF ORD/MDW
BY 22 OR 23Z AND GYY TOWARD 00Z OR A BIT AFTER.
MDB
FROM 18Z...
BAND OF SHRA/TSRA CONTINUES TO MOVE EASTWARD INTO NORTH CENTRAL
ILLINOIS WITH SOME SPOTTY ACTIVITY NOW POPPING UP AHEAD OF IT.
WITH AN UPPER LEVEL WAVE LOOKING TO BE THE MAIN DRIVER OF THIS
PRECIP...POSSIBLY ALONG WITH A NEWLY DEVELOPED LOW LEVEL
CIRCULATION...A MORE EASTWARD TRACK LOOKS TO CONTINUE. THIS WILL
BRING THE ACTIVITY ACROSS RFD OVER THE NEXT FEW HOURS WITH THE CHI
METRO BEING AFFECTED MID/LATE AFTERNOON...WITH THE MOST ORGANIZED
COVERAGE EXPECTED 22/23Z OR SO. MOVEMENT HAS BEEN SLOW SO DURATION
IS A CONCERN BUT OVERALL COVERAGE HAS DECREASED. MAY NEED TO
UPDATE THE CHI AREA TAFS WITH A TEMPO GROUP. OTHERWISE THIS WILL
PASS BY EARLY EVENING LEAVING DRY CONDITIONS BUT A PUSH OF WARMER
AIR WILL ARRIVE LATER TONIGHT AND MAY KICK OFF SCATTERED SHRA/TSRA
DEVELOPMENT EARLY THURSDAY MORNING. CHANCE CONTINUES TO BE 20 TO
30 PERCENT SO OPTED TO KEEP VCSH AND PROB30 TS MENTION FOR NOW
WITH LOW CHANCES CONTINUING THROUGH THE REST OF THE DAY. SOUTH-
SOUTHWEST WINDS LOOK TO BECOME GUSTY BY LATE MORNING WITH GUSTS
AROUND 20 EXPECTED...THOUGH THERE IS SOME SUGGESTION OF 20-25 KT
GUSTS.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* MEDIUM-HIGH CONFIDENCE IN SHRA THROUGH 00 UTC.
* MEDIUM-HIGH CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY
MORNING IS LOW.
MDB/KB
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.
FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.
SATURDAY THROUGH TUESDAY...VFR. WX NIL.
KREIN
&&
.MARINE...
256 PM CDT
AN AREA OF LOW PRESSURE CENTERED OVER THE DAKOTAS IS TO WEAKEN
SLIGHTLY AS IT TRACKS NORTHEAST TO SOUTHERN CANADA BY MIDDAY
THURSDAY. THE LOW THEN DEEPENS FRIDAY AND MOVES ACROSS JAMES BAY.
AN ASSOCIATED COLD FRONT WILL MOVE SOUTHEASTWARD AND ACROSS LAKE
MI DURING FRIDAY SHIFTING SOUTH AND SOUTHWESTERLY WINDS TO OUT OF
THE WEST AND NORTHWEST AND INCREASING TO STRONG BREEZES. AS LARGE
HIGH PRESSURE BUILDS SOUTHEASTWARD ACROSS THE WESTERN GREAT LAKES
FRIDAY THROUGH SUNDAY WINDS WILL GRADUALLY RELAX AS THEY VEER
THROUGH NORTH AND EAST TO SOUTHEAST.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
341 PM CDT WED SEP 18 2013
.DISCUSSION...
336 PM CDT
MAIN CHALLENGES/CONCERNS THIS FORECAST PERIOD ARE WITH SHOWERS AND
THUNDERSTORMS IN THE NEAR TERM...POSSIBLE PERSISTENT
SHOWERS/THUNDERSTORMS OVERNIGHT...AS WELL AS BETTER CHANCES FOR
SHOWERS/THUNDERSTORMS THURSDAY NIGHT INTO FRIDAY MORNING.
CONTINUE TO MONITOR AREA OF SHOWERS AND THUNDERSTORMS ACROSS NORTH
CENTRAL ILLINOIS THAT HAVE CONTINUED TO SLOWLY MOVE EAST TODAY.
LATEST RADAR IMAGERY DEPICTING A CONTINUED DEVELOPING TREND IN
BOTH COVERAGE AND INTENSITY WITH THIS AREA OF PRECIPITATION...AND
EXPECT THIS TO CONTINUE THROUGH THE AFTERNOON AND EARLY EVENING.
MCV IS THE MAIN DRIVING FORCE FOR THESE
SHOWERS/THUNDERSTORMS...WITH LATEST RAP ANALYSIS SHOWING LOWERING
CIN AND AN AXIS OF 1000 J/KG OF SB CAPE EXTENDING INTO NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH NOT THE GREATEST...THESE
CONDITIONS WILL BE ENOUGH TO HELP THIS PRECIP TO HOLD TOGETHER
WHILE IT SLOWLY MOVES THROUGH NORTHEAST ILLINOIS THIS AFTERNOON
AND THEN NORTHWEST INDIANA THROUGH EARLY EVENING. ALTHOUGH
WIDESPREAD SEVERE WEATHER IS NOT ANTICIPATED...A PORTION OF THESE
STORMS ALONG THE I-80 CORRIDOR HAVE EXHIBITED SOME STRENGTHENING
TRENDS WITH BRIEF HIGHER WIND SIGNATURES. SO FOR THIS
AFTERNOON/EARLY EVENING...EXPECT ANY OF THE STRONGER STORMS IN
THIS GENERAL AREA TO BE CAPABLE OF PRODUCING SPORADIC WIND GUSTS
TO 50 MPH...CONTINUOUS LIGHTNING...AND BRIEF HEAVY RAINFALL WITH
AN OUTSIDE POSSIBILITY OF AN ISOLATED SEVERE WIND THREAT.
WITH THE DEPARTURE OF THESE THUNDERSTORMS...MOST OF THE CWA SHOULD
OBSERVE A LULL IN PRECIP BEFORE SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE ONCE AGAIN OVER NIGHT. SEVERAL WEAK MID LEVEL FEATURES
WILL CONTINUE TO TRAVERSE CURRENT ZONAL FLOW OVERHEAD...WITH
LOW/MID LEVEL FLOW VEERING OVERNIGHT. AS THIS OCCURS...IT APPEARS
AS BETTER WAA WILL ORIENT ITSELF MORE TOWARDS NORTHERN ILLINOIS.
ALTHOUGH CONFIDENCE IS NOT THE GREATEST FOR COVERAGE TONIGHT...DID
MAINTAIN LOW CHANCE POPS FOR MOST AREAS MAINLY AFTER MIDNIGHT
OWING TO THIS POTENTIAL. WHATEVER DOES DEVELOP SHOULD BE MORE
SCATTERED IN NATURE...AND THEN BEGIN SHIFTING EAST OUT OF THE CWA
WHILE DIMINISHING EARLY THURSDAY MORNING. WITH BROAD SOUTHWESTERLY
FLOW PERSISTING ON THURSDAY AND A FAIRLY MOIST ENVIRONMENT
OVERHEAD...SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE.
ALTHOUGH...CHANCES FOR PRECIPITATION SHOULD REMAIN LOW WITH ONCE
AGAIN ANYTHING THAT DOES DEVELOP REMAINING SCATTERED. WITH THIS
PERSISTENT WAA...CONTINUED WARMUP WILL CONTINUE ON THURSDAY. MADE
LITTLE ADJUSTMENTS TO MAX TEMPS FOR THURSDAY KEEPING UPPER 80S FOR
MOST LOCATIONS...WITH SOME UNCERTAINTIES TO PRECIP AND EVEN CLOUD
COVER REMAINING. IF ENOUGH CLEARING OCCURS...THERMO PROFILES WILL
BE SUPPORTIVE OF SOME LOCATIONS REACHING OR SLIGHTLY EXCEEDING 90
DEGREES.
MAIN FOCUS FOR THUNDERSTORM DEVELOPMENT SHIFTS TOWARDS THE LATE
AFTERNOON AND EARLY EVENING WITH AN APPROACHING TROUGH OF LOW
PRESSURE AND COLD FRONT. AS LARGE VORT MAX DROPS SOUTHEAST ACROSS
THE NORTHERN PLAINS...SEVERAL WAVES OF ENERGY WILL LIFT NORTHEAST
ACROSS THE REGION. THIS WILL HELP TO SHIFT THIS TROUGH/FRONT AS WELL
AS INDUCING SOME FURTHER PRESSURE FALLS OUT AHEAD OF IT. WITH
POTENTIAL FOR PRE FRONTAL TROUGHINESS TO OCCUR TOMORROW
AFTERNOON...SOME GUIDANCE CONTINUES TO DEVELOP PRECIP OUT AHEAD OF
THIS FRONT. ALTHOUGH I FEEL THIS IS A BIT OVERDONE...AND HAVE HELD
BACK ON POPS FOR THURSDAY DURING THE DAY. HAVE EVEN TRENDED
TOWARDS A SLOWER SOLUTION/TREND WITH THIS FRONT/TROUGH WITH BEST
CHANCES FOR SHOWERS/THUNDERSTORMS REMAINING OVER WEST/NORTHWEST
ILLINOIS FOR MOST OF THURSDAY NIGHT. ITS NOT UNTIL EARLY FRIDAY
MORNING THAT THIS FRONT GETS A GOOD SOUTHEAST PUSH WITH BEST
FORCING MOVING OVERHEAD. GOOD SWATH OF PRECIP SHOULD SHIFT
SOUTHEAST ACROSS THE ENTIRE CWA THROUGH MID DAY FRIDAY...WITH THIS
PRECIP THEN EXPECTED TO SHIFT OUT OF THE AREA THROUGH THE
AFTERNOON. IT DOES APPEAR AS IF THE STRONGER STORMS SHOULD REMAIN
JUST WEST OF THE CWA...BUT WITH SOME POTENTIAL FOR THEM TO REACH
THE FAR WESTERN CWA THURSDAY EVENING/NIGHT. IF INSTABILITY CAN
INCREASE ON FRIDAY...THERE IS THE POTENTIAL FOR A LINGERING STRONG
TO SEVERE THREAT ACROSS THE CWA BEFORE THE STORMS SHIFT OUT OF THE
CWA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* SHRA/TSRA EXPECTED IN THE AREA FROM 2030Z TIL 22 OR 23Z...MDW MAY
SEE MOST DIRECT EFFECTS. BRIEF IFR VSBY POSSIBLE UNDER HEAVIEST
CELLS.
* LOW CHANCE FOR ADDITIONAL SHRA/TSRA THURSDAY MORNING.
MDB
//DISCUSSION...UPDATED 20Z...
TSRA SITUATION HAS EVOLVED OVER THE LAST 2 HOURS. LOW LEVEL
CIRCULATION HAS CONTINUED TO DEVELOP AND HAS FOCUSED DEVELOPMENT
TO ITS SOUTHEAST LEADING TO HIGHER TSRA COVERAGE FROM DKB
SOUTHWESTWARD...WITH THE EARLIER AREA OF CONVECTION TO THE NORTH
SLOWLY FADING. BASED ON THESE TRENDS HAVE SPED UP TIMING OF TSRA
IN THE CHI AREA TAFS AND ADDED TSRA TO GYY. NEW ACTIVITY IS MOVING
A BIT MORE QUICKLY SO IT APPEARS THAT IT MAY BE CLEAR OF ORD/MDW
BY 22 OR 23Z AND GYY TOWARD 00Z OR A BIT AFTER.
MDB
FROM 18Z...
BAND OF SHRA/TSRA CONTINUES TO MOVE EASTWARD INTO NORTH CENTRAL
ILLINOIS WITH SOME SPOTTY ACTIVITY NOW POPPING UP AHEAD OF IT.
WITH AN UPPER LEVEL WAVE LOOKING TO BE THE MAIN DRIVER OF THIS
PRECIP...POSSIBLY ALONG WITH A NEWLY DEVELOPED LOW LEVEL
CIRCULATION...A MORE EASTWARD TRACK LOOKS TO CONTINUE. THIS WILL
BRING THE ACTIVITY ACROSS RFD OVER THE NEXT FEW HOURS WITH THE CHI
METRO BEING AFFECTED MID/LATE AFTERNOON...WITH THE MOST ORGANIZED
COVERAGE EXPECTED 22/23Z OR SO. MOVEMENT HAS BEEN SLOW SO DURATION
IS A CONCERN BUT OVERALL COVERAGE HAS DECREASED. MAY NEED TO
UPDATE THE CHI AREA TAFS WITH A TEMPO GROUP. OTHERWISE THIS WILL
PASS BY EARLY EVENING LEAVING DRY CONDITIONS BUT A PUSH OF WARMER
AIR WILL ARRIVE LATER TONIGHT AND MAY KICK OFF SCATTERED SHRA/TSRA
DEVELOPMENT EARLY THURSDAY MORNING. CHANCE CONTINUES TO BE 20 TO
30 PERCENT SO OPTED TO KEEP VCSH AND PROB30 TS MENTION FOR NOW
WITH LOW CHANCES CONTINUING THROUGH THE REST OF THE DAY. SOUTH-
SOUTHWEST WINDS LOOK TO BECOME GUSTY BY LATE MORNING WITH GUSTS
AROUND 20 EXPECTED...THOUGH THERE IS SOME SUGGESTION OF 20-25 KT
GUSTS.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM-HIGH CONFIDENCE IN TSRA OCCURRENCE AND TIMING.
* MEDIUM-HIGH CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY
MORNING IS LOW.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.
FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.
SATURDAY THROUGH TUESDAY...VFR. WX NIL.
KREIN
&&
.MARINE...
256 PM CDT
AN AREA OF LOW PRESSURE CENTERED OVER THE DAKOTAS IS TO WEAKEN
SLIGHTLY AS IT TRACKS NORTHEAST TO SOUTHERN CANADA BY MIDDAY
THURSDAY. THE LOW THEN DEEPENS FRIDAY AND MOVES ACROSS JAMES BAY.
AN ASSOCIATED COLD FRONT WILL MOVE SOUTHEASTWARD AND ACROSS LAKE
MI DURING FRIDAY SHIFTING SOUTH AND SOUTHWESTERLY WINDS TO OUT OF
THE WEST AND NORTHWEST AND INCREASING TO STRONG BREEZES. AS LARGE
HIGH PRESSURE BUILDS SOUTHEASTWARD ACROSS THE WESTERN GREAT LAKES
FRIDAY THROUGH SUNDAY WINDS WILL GRADUALLY RELAX AS THEY VEER
THROUGH NORTH AND EAST TO SOUTHEAST.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
300 PM CDT WED SEP 18 2013
.DISCUSSION...
1057 AM CDT
MAIN SHORT TERM CONCERN IS POTENTIAL FOR EAST CENTRAL IA
THUNDERSTORMS REACHING THE WESTERN AND FAR NORTHER EASTERN
PORTIONS OF THE FORECAST AREA LATE THIS MORNING THROUGH THE FIRST
PART OF THE AFTERNOON. OTHER CONCERNS SKY COVER AND TEMPERATURE
TRENDS/MAX TEMPS.
TSRA THAT DEVELOPED OVER WESTERN IA LATE LAST NIGHT HAD BEEN
MOVING STEADILY NORTHEASTWARD DURING THE PREDAWN AND EARLY
MORNING HOURS BUT HAVE TAKEN ON A MORE EASTERLY DIRECTION OVER
THE LAST FEW HOURS AS THEY HAVE APPROACHED THE TOP OF A FLAT
UPPER RIDGE OVER THE LOCAL AREA IN THE WAKE OF THE COMPACT UPPER
LOW THAT HAD MOVED FROM OVER SOUTHERN LAKE MI TO WESTERN LAKE
ERIE SINCE LATE LAST NIGHT.
THIS CURRENT CONVECTION APPEARS TO BE WHERE LOWER AND MID LEVEL
WAA ARE MAXIMIZING ISENTROPIC ASCENT IN AN AREA OF STEEP MID
LEVEL LAPSE RATES. FORCING IN AN COINCIDING WITH AN AREA OF STEEP
MID LEVEL LAPSE RATES. LOWER AND MID LEVEL THETA-E ADVECTION
APPEARS TO BE ALSO HELPING IN THE TURN TO A MORE EASTERLY
MOVEMENT.
PURE EXTRAPOLATION OF THIS RECENT MOVEMENT WOULD LEAD ONE TO
BELIEVE THAT THE TSRA WOULD CONTINUE ACROSS NW TO N CENTRAL IL
AND NE IL DURING THE LATE MORNING THROUGH MID AFTERNOON.
HOWEVER...HIGHER RESOLUTION SHORT TERM MODEL OUTPUT INCLUDING
CONVECTIVE PRECIP...850-700 EQ POT TEMP ADV...K INDEX MID LEVEL
LAPSE RATES ARE SUGGESTING THAT THIS ACTIVITY WILL MAINTAIN AN
OVERALL ENE TO NE MOVEMENT PUTTING JUST N CENTRAL AND FAR NE IL
AT ANY SIGNIFICANT RISK OF SEEING THUNDERSTORMS.
WITH THE QUICK CLEARING FOLLOWING THE DEPARTURE OF THE UPPER LOW
EARLY THIS MORNING TEMPERATURES RESPONDED BY QUICKLY RISING INTO
THE LOWER AND MID 70S. WHILE SOME OF THE ANVIL FROM THE TS
CLUSTER IN FAR E CENTRAL IA IS EXPECTED TO MOVE THE NORTH PORTION
OF THE FA DURING THE AFTERNOON AND CUT INTO THE SURFACE
HEATING...FORECAST SOUNDINGS PREDICT HIGHS IN THE LOWER AND MID
80S... EXCEPT ALONG THE NORTH LAKE SHORE WHERE A LAKE BREEZE
EXPECTED TO MAKE LITTLE INLAND ADVANCEMENT KEEPS THIS AREA IN THE
MID 70S.
TRS
//PREV DISCUSSION...
330 AM CDT
THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.
SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.
TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.
SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.
TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.
THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOBARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.
THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* SHRA/TSRA EXPECTED IN THE AREA FROM 2030Z TIL 22 OR 23Z...MDW MAY
SEE MOST DIRECT EFFECTS. BRIEF IFR VSBY POSSIBLE UNDER HEAVIEST
CELLS.
* LOW CHANCE FOR ADDITIONAL SHRA/TSRA THURSDAY MORNING.
MDB
//DISCUSSION...UPDATED 20Z...
TSRA SITUATION HAS EVOLVED OVER THE LAST 2 HOURS. LOW LEVEL
CIRCULATION HAS CONTINUED TO DEVELOP AND HAS FOCUSED DEVELOPMENT
TO ITS SOUTHEAST LEADING TO HIGHER TSRA COVERAGE FROM DKB
SOUTHWESTWARD...WITH THE EARLIER AREA OF CONVECTION TO THE NORTH
SLOWLY FADING. BASED ON THESE TRENDS HAVE SPED UP TIMING OF TSRA
IN THE CHI AREA TAFS AND ADDED TSRA TO GYY. NEW ACTIVITY IS MOVING
A BIT MORE QUICKLY SO IT APPEARS THAT IT MAY BE CLEAR OF ORD/MDW
BY 22 OR 23Z AND GYY TOWARD 00Z OR A BIT AFTER.
MDB
FROM 18Z...
BAND OF SHRA/TSRA CONTINUES TO MOVE EASTWARD INTO NORTH CENTRAL
ILLINOIS WITH SOME SPOTTY ACTIVITY NOW POPPING UP AHEAD OF IT.
WITH AN UPPER LEVEL WAVE LOOKING TO BE THE MAIN DRIVER OF THIS
PRECIP...POSSIBLY ALONG WITH A NEWLY DEVELOPED LOW LEVEL
CIRCULATION...A MORE EASTWARD TRACK LOOKS TO CONTINUE. THIS WILL
BRING THE ACTIVITY ACROSS RFD OVER THE NEXT FEW HOURS WITH THE CHI
METRO BEING AFFECTED MID/LATE AFTERNOON...WITH THE MOST ORGANIZED
COVERAGE EXPECTED 22/23Z OR SO. MOVEMENT HAS BEEN SLOW SO DURATION
IS A CONCERN BUT OVERALL COVERAGE HAS DECREASED. MAY NEED TO
UPDATE THE CHI AREA TAFS WITH A TEMPO GROUP. OTHERWISE THIS WILL
PASS BY EARLY EVENING LEAVING DRY CONDITIONS BUT A PUSH OF WARMER
AIR WILL ARRIVE LATER TONIGHT AND MAY KICK OFF SCATTERED SHRA/TSRA
DEVELOPMENT EARLY THURSDAY MORNING. CHANCE CONTINUES TO BE 20 TO
30 PERCENT SO OPTED TO KEEP VCSH AND PROB30 TS MENTION FOR NOW
WITH LOW CHANCES CONTINUING THROUGH THE REST OF THE DAY. SOUTH-
SOUTHWEST WINDS LOOK TO BECOME GUSTY BY LATE MORNING WITH GUSTS
AROUND 20 EXPECTED...THOUGH THERE IS SOME SUGGESTION OF 20-25 KT
GUSTS.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM-HIGH CONFIDENCE IN TSRA OCCURRENCE AND TIMING.
* MEDIUM-HIGH CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY
MORNING IS LOW.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.
FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.
SATURDAY THROUGH TUESDAY...VFR. WX NIL.
KREIN
&&
.MARINE...
256 PM CDT
AN AREA OF LOW PRESSURE CENTERED OVER THE DAKOTAS IS TO WEAKEN
SLIGHTLY AS IT TRACKS NORTHEAST TO SOUTHERN CANADA BY MIDDAY
THURSDAY. THE LOW THEN DEEPENS FRIDAY AND MOVES ACROSS JAMES BAY.
AN ASSOCIATED COLD FRONT WILL MOVE SOUTHEASTWARD AND ACROSS LAKE
MI DURING FRIDAY SHIFTING SOUTH AND SOUTHWESTERLY WINDS TO OUT OF
THE WEST AND NORTHWEST AND INCREASING TO STRONG BREEZES. AS LARGE
HIGH PRESSURE BUILDS SOUTHEASTWARD ACROSS THE WESTERN GREAT LAKES
FRIDAY THROUGH SUNDAY WINDS WILL GRADUALLY RELAX AS THEY VEER
THROUGH NORTH AND EAST TO SOUTHEAST.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
245 PM CDT WED SEP 18 2013
.DISCUSSION...
1057 AM CDT
MAIN SHORT TERM CONCERN IS POTENTIAL FOR EAST CENTRAL IA
THUNDERSTORMS REACHING THE WESTERN AND FAR NORTHER EASTERN
PORTIONS OF THE FORECAST AREA LATE THIS MORNING THROUGH THE FIRST
PART OF THE AFTERNOON. OTHER CONCERNS SKY COVER AND TEMPERATURE
TRENDS/MAX TEMPS.
TSRA THAT DEVELOPED OVER WESTERN IA LATE LAST NIGHT HAD BEEN
MOVING STEADILY NORTHEASTWARD DURING THE PREDAWN AND EARLY
MORNING HOURS BUT HAVE TAKEN ON A MORE EASTERLY DIRECTION OVER
THE LAST FEW HOURS AS THEY HAVE APPROACHED THE TOP OF A FLAT
UPPER RIDGE OVER THE LOCAL AREA IN THE WAKE OF THE COMPACT UPPER
LOW THAT HAD MOVED FROM OVER SOUTHERN LAKE MI TO WESTERN LAKE
ERIE SINCE LATE LAST NIGHT.
THIS CURRENT CONVECTION APPEARS TO BE WHERE LOWER AND MID LEVEL
WAA ARE MAXIMIZING ISENTROPIC ASCENT IN AN AREA OF STEEP MID
LEVEL LAPSE RATES. FORCING IN AN COINCIDING WITH AN AREA OF STEEP
MID LEVEL LAPSE RATES. LOWER AND MID LEVEL THETA-E ADVECTION
APPEARS TO BE ALSO HELPING IN THE TURN TO A MORE EASTERLY
MOVEMENT.
PURE EXTRAPOLATION OF THIS RECENT MOVEMENT WOULD LEAD ONE TO
BELIEVE THAT THE TSRA WOULD CONTINUE ACROSS NW TO N CENTRAL IL
AND NE IL DURING THE LATE MORNING THROUGH MID AFTERNOON.
HOWEVER...HIGHER RESOLUTION SHORT TERM MODEL OUTPUT INCLUDING
CONVECTIVE PRECIP...850-700 EQ POT TEMP ADV...K INDEX MID LEVEL
LAPSE RATES ARE SUGGESTING THAT THIS ACTIVITY WILL MAINTAIN AN
OVERALL ENE TO NE MOVEMENT PUTTING JUST N CENTRAL AND FAR NE IL
AT ANY SIGNIFICANT RISK OF SEEING THUNDERSTORMS.
WITH THE QUICK CLEARING FOLLOWING THE DEPARTURE OF THE UPPER LOW
EARLY THIS MORNING TEMPERATURES RESPONDED BY QUICKLY RISING INTO
THE LOWER AND MID 70S. WHILE SOME OF THE ANVIL FROM THE TS
CLUSTER IN FAR E CENTRAL IA IS EXPECTED TO MOVE THE NORTH PORTION
OF THE FA DURING THE AFTERNOON AND CUT INTO THE SURFACE
HEATING...FORECAST SOUNDINGS PREDICT HIGHS IN THE LOWER AND MID
80S... EXCEPT ALONG THE NORTH LAKE SHORE WHERE A LAKE BREEZE
EXPECTED TO MAKE LITTLE INLAND ADVANCEMENT KEEPS THIS AREA IN THE
MID 70S.
TRS
//PREV DISCUSSION...
330 AM CDT
THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.
SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.
TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.
SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.
TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.
THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.
THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* SHRA/TSRA EXPECTED IN THE AREA FROM 2030Z TIL 22 OR 23Z...MDW MAY
SEE MOST DIRECT EFFECTS. BRIEF IFR VSBY POSSIBLE UNDER HEAVIEST
CELLS.
* LOW CHANCE FOR ADDITIONAL SHRA/TSRA THURSDAY MORNING.
MDB
//DISCUSSION...UPDATED 20Z...
TSRA SITUATION HAS EVOLVED OVER THE LAST 2 HOURS. LOW LEVEL
CIRCULATION HAS CONTINUED TO DEVELOP AND HAS FOCUSED DEVELOPMENT
TO ITS SOUTHEAST LEADING TO HIGHER TSRA COVERAGE FROM DKB
SOUTHWESTWARD...WITH THE EARLIER AREA OF CONVECTION TO THE NORTH
SLOWLY FADING. BASED ON THESE TRENDS HAVE SPED UP TIMING OF TSRA
IN THE CHI AREA TAFS AND ADDED TSRA TO GYY. NEW ACTIVITY IS MOVING
A BIT MORE QUICKLY SO IT APPEARS THAT IT MAY BE CLEAR OF ORD/MDW
BY 22 OR 23Z AND GYY TOWARD 00Z OR A BIT AFTER.
MDB
FROM 18Z...
BAND OF SHRA/TSRA CONTINUES TO MOVE EASTWARD INTO NORTH CENTRAL
ILLINOIS WITH SOME SPOTTY ACTIVITY NOW POPPING UP AHEAD OF IT.
WITH AN UPPER LEVEL WAVE LOOKING TO BE THE MAIN DRIVER OF THIS
PRECIP...POSSIBLY ALONG WITH A NEWLY DEVELOPED LOW LEVEL
CIRCULATION...A MORE EASTWARD TRACK LOOKS TO CONTINUE. THIS WILL
BRING THE ACTIVITY ACROSS RFD OVER THE NEXT FEW HOURS WITH THE CHI
METRO BEING AFFECTED MID/LATE AFTERNOON...WITH THE MOST ORGANIZED
COVERAGE EXPECTED 22/23Z OR SO. MOVEMENT HAS BEEN SLOW SO DURATION
IS A CONCERN BUT OVERALL COVERAGE HAS DECREASED. MAY NEED TO
UPDATE THE CHI AREA TAFS WITH A TEMPO GROUP. OTHERWISE THIS WILL
PASS BY EARLY EVENING LEAVING DRY CONDITIONS BUT A PUSH OF WARMER
AIR WILL ARRIVE LATER TONIGHT AND MAY KICK OFF SCATTERED SHRA/TSRA
DEVELOPMENT EARLY THURSDAY MORNING. CHANCE CONTINUES TO BE 20 TO
30 PERCENT SO OPTED TO KEEP VCSH AND PROB30 TS MENTION FOR NOW
WITH LOW CHANCES CONTINUING THROUGH THE REST OF THE DAY. SOUTH-
SOUTHWEST WINDS LOOK TO BECOME GUSTY BY LATE MORNING WITH GUSTS
AROUND 20 EXPECTED...THOUGH THERE IS SOME SUGGESTION OF 20-25 KT
GUSTS.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM-HIGH CONFIDENCE IN TSRA OCCURRENCE AND TIMING.
* MEDIUM-HIGH CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY
MORNING IS LOW.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.
FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.
SATURDAY THROUGH TUESDAY...VFR. WX NIL.
KREIN
&&
.MARINE...
255 AM CDT
A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
116 PM CDT WED SEP 18 2013
.DISCUSSION...
1057 AM CDT
MAIN SHORT TERM CONCERN IS POTENTIAL FOR EAST CENTRAL IA
THUNDERSTORMS REACHING THE WESTERN AND FAR NORTHER EASTERN
PORTIONS OF THE FORECAST AREA LATE THIS MORNING THROUGH THE FIRST
PART OF THE AFTERNOON. OTHER CONCERNS SKY COVER AND TEMPERATURE
TRENDS/MAX TEMPS.
TRSA THAT DEVELOPED OVER WESTERN IA LATE LAST NIGHT HAD BEEN
MOVING STEADILY NORTHEASTWARD DURING THE PREDAWN AND EARLY
MORNING HOURS BUT HAVE TAKEN ON A MORE EASTERLY DIRECTION OVER
THE LAST FEW HOURS AS THEY HAVE APPROACHED THE TOP OF A FLAT
UPPER RIDGE OVER THE LOCAL AREA IN THE WAKE OF THE COMPACT UPPER
LOW THAT HAD MOVED FROM OVER SOUTHERN LAKE MI TO WESTERN LAKE
ERIE SINCE LATE LAST NIGHT.
THIS CURRENT CONVECTION APPEARS TO BE WHERE LOWER AND MID LEVEL
WAA ARE MAXIMIZING ISENTROPIC ASCENT IN AN AREA OF STEEP MID
LEVEL LAPSE RATES. FORCING IN AN COINCIDING WITH AN AREA OF STEEP
MID LEVEL LAPSE RATES. LOWER AND MID LEVEL THETA-E ADVECTION
APPEARS TO BE ALSO HELPING IN THE TURN TO A MORE EASTERLY
MOVEMENT.
PURE EXTRAPOLATION OF THIS RECENT MOVEMENT WOULD LEAD ONE TO
BELIEVE THAT THE TSRA WOULD CONTINUE ACROSS NW TO N CENTRAL IL
AND NE IL DURING THE LATE MORNING THROUGH MID AFTERNOON.
HOWEVER...HIGHER RESOLUTION SHORT TERM MODEL OUTPUT INCLUDING
CONVECTIVE PRECIP...850-700 EQ POT TEMP ADV...K INDEX MID LEVEL
LAPSE RATES ARE SUGGESTING THAT THIS ACTIVITY WILL MAINTAIN AN
OVERALL ENE TO NE MOVEMENT PUTTING JUST N CENTRAL AND FAR NE IL
AT ANY SIGNIFICANT RISK OF SEEING THUNDERSTORMS.
WITH THE QUICK CLEARING FOLLOWING THE DEPARTURE OF THE UPPER LOW
EARLY THIS MORNING TEMPERATURES RESPONDED BY QUICKLY RISING INTO
THE LOWER AND MID 70S. WHILE SOME OF THE ANVIL FROM THE TS
CLUSTER IN FAR E CENTRAL IA IS EXPECTED TO MOVE THE NORTH PORTION
OF THE FA DURING THE AFTERNOON AND CUT INTO THE SURFACE
HEATING...FORECAST SOUNDINGS PREDICT HIGHS IN THE LOWER AND MID
80S... EXCEPT ALONG THE NORTH LAKE SHORE WHERE A LAKE BREEZE
EXPECTED TO MAKE LITTLE INLAND ADVANCEMENT KEEPS THIS AREA IN THE
MID 70S.
TRS
//PREV DISCUSSION...
330 AM CDT
THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.
SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.
TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.
SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.
TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.
THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.
THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* POSSIBLE TSRA THIS AFTERNOON...ISOLATED CHANCE TOWARD 20Z WITH
MORE ORGANIZED CHANCE 22 OR 23Z.
* LOW CHANCE FOR SHRA/TSRA THURSDAY MORNING.
MDB
//DISCUSSION...UPDATED 18Z...
BAND OF SHRA/TSRA CONTINUES TO MOVE EASTWARD INTO NORTH CENTRAL
ILLINOIS WITH SOME SPOTTY ACTIVITY NOW POPPING UP AHEAD OF IT.
WITH AN UPPER LEVEL WAVE LOOKING TO BE THE MAIN DRIVER OF THIS
PRECIP...POSSIBLY ALONG WITH A NEWLY DEVELOPED LOW LEVEL
CIRCULATION...A MORE EASTWARD TRACK LOOKS TO CONTINUE. THIS WILL
BRING THE ACTIVITY ACROSS RFD OVER THE NEXT FEW HOURS WITH THE CHI
METRO BEING AFFECTED MID/LATE AFTERNOON...WITH THE MOST ORGANIZED
COVERAGE EXPECTED 22/23Z OR SO. MOVEMENT HAS BEEN SLOW SO DURATION
IS A CONCERN BUT OVERALL COVERAGE HAS DECREASED. MAY NEED TO
UPDATE THE CHI AREA TAFS WITH A TEMPO GROUP. OTHERWISE THIS WILL
PASS BY EARLY EVENING LEAVING DRY CONDITIONS BUT A PUSH OF WARMER
AIR WILL ARRIVE LATER TONIGHT AND MAY KICK OFF SCATTERED SHRA/TSRA
DEVELOPMENT EARLY THURSDAY MORNING. CHANCE CONTINUES TO BE 20 TO
30 PERCENT SO OPTED TO KEEP VCSH AND PROB30 TS MENTION FOR NOW
WITH LOW CHANCES CONTINUING THROUGH THE REST OF THE DAY. SOUTH-
SOUTHWEST WINDS LOOK TO BECOME GUSTY BY LATE MORNING WITH GUSTS
AROUND 20 EXPECTED...THOUGH THERE IS SOME SUGGESTION OF 20-25 KT
GUSTS.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM-HIGH CONFIDENCE THAT SHRA/TSRA WILL BE IN THE AREA
MID/LATE AFTERNOON.
* MEDIUM-HIGH CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY
MORNING IS LOW.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.
FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.
SATURDAY THROUGH TUESDAY...VFR. WX NIL.
KREIN
&&
.MARINE...
255 AM CDT
A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1116 AM CDT WED SEP 18 2013
.DISCUSSION...
1057 AM CDT
MAIN SHORT TERM CONCERN IS POTENTIAL FOR EAST CENTRAL IA
THUNDERSTORMS REACHING THE WESTERN AND FAR NORTHER EASTERN
PORTIONS OF THE FORECAST AREA LATE THIS MORNING THROUGH THE FIRST
PART OF THE AFTERNOON. OTHER CONCERNS SKY COVER AND TEMPERATURE
TRENDS/MAX TEMPS.
TRSA THAT DEVELOPED OVER WESTERN IA LATE LAST NIGHT HAD BEEN
MOVING STEADILY NORTHEASTWARD DURING THE PREDAWN AND EARLY
MORNING HOURS BUT HAVE TAKEN ON A MORE EASTERLY DIRECTION OVER
THE LAST FEW HOURS AS THEY HAVE APPROACHED THE TOP OF A FLAT
UPPER RIDGE OVER THE LOCAL AREA IN THE WAKE OF THE COMPACT UPPER
LOW THAT HAD MOVED FROM OVER SOUTHERN LAKE MI TO WESTERN LAKE
ERIE SINCE LATE LAST NIGHT.
THIS CURRENT CONVECTION APPEARS TO BE WHERE LOWER AND MID LEVEL
WAA ARE MAXIMIZING ISENTROPIC ASCENT IN AN AREA OF STEEP MID
LEVEL LAPSE RATES. FORCING IN AN COINCIDING WITH AN AREA OF STEEP
MID LEVEL LAPSE RATES. LOWER AND MID LEVEL THETA-E ADVECTION
APPEARS TO BE ALSO HELPING IN THE TURN TO A MORE EASTERLY
MOVEMENT.
PURE EXTRAPOLATION OF THIS RECENT MOVEMENT WOULD LEAD ONE TO
BELIEVE THAT THE TSRA WOULD CONTINUE ACROSS NW TO N CENTRAL IL
AND NE IL DURING THE LATE MORNING THROUGH MID AFTERNOON.
HOWEVER...HIGHER RESOLUTION SHORT TERM MODEL OUTPUT INCLUDING
CONVECTIVE PRECIP...850-700 EQ POT TEMP ADV...K INDEX MID LEVEL
LAPSE RATES ARE SUGGESTING THAT THIS ACTIVITY WILL MAINTAIN AN
OVERALL ENE TO NE MOVEMENT PUTTING JUST N CENTRAL AND FAR NE IL
AT ANY SIGNIFICANT RISK OF SEEING THUNDERSTORMS.
WITH THE QUICK CLEARING FOLLOWING THE DEPARTURE OF THE UPPER LOW
EARLY THIS MORNING TEMPERATURES RESPONDED BY QUICKLY RISING INTO
THE LOWER AND MID 70S. WHILE SOME OF THE ANVIL FROM THE TS
CLUSTER IN FAR E CENTRAL IA IS EXPECTED TO MOVE THE NORTH PORTION
OF THE FA DURING THE AFTERNOON AND CUT INTO THE SURFACE
HEATING...FORECAST SOUNDINGS PREDICT HIGHS IN THE LOWER AND MID
80S... EXCEPT ALONG THE NORTH LAKE SHORE WHERE A LAKE BREEZE
EXPECTED TO MAKE LITTLE INLAND ADVANCEMENT KEEPS THIS AREA IN THE
MID 70S.
TRS
//PREV DISCUSSION...
330 AM CDT
THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.
SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.
TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.
SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.
TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.
THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.
THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* SSW WINDS WITH OCCASIONAL GUSTS NEAR 20 KT.
* SOME CHANCE FOR SHRA/TSRA TO BE NEARBY OR JUST NORTHWEST AFTER
APPROX 21Z...BULK OF ACTIVITY EXPECTED TO REMAIN N OF TERMINALS.
* LOW CHANCE SHRA/TSRA EARLY THURSDAY MORNING.
MDB
//DISCUSSION...UPDATED 16Z...
STILL WATCHING CLUSTER OF SHRA/TSRA WORKING INTO FAR NW ILLINOIS
AT 16Z BUT TRENDS CONTINUE TO SHOW IT INCHING MORE TO THE NE.
EXPECT THIS NE TREND TO CONTINUE OVER THE NEXT FEW HOURS. RFD
LOOKS TO BE DIRECTLY AFFECTED AROUND 18Z...WITH THE ACTIVITY
PASSING NW OF ORD TOWARD OR AFTER 21Z IF THE SOUTHERN PORTION CAN
HOLD TOGETHER. SPOTTY ACTIVITY COULD OCCUR ACROSS THE CHICAGO AREA
AS THIS BAND PASSES TO THE NORTH BUT POTENTIAL IS TOO LOW TO
INCLUDE IN THE TAF. OTHERWISE WINDS HAVE COME AROUND TO S-SSW NOW
THAT SKIES HAVE SCATTERED TO SOME DEGREE AND SPORADIC GUSTS TO
NEAR 20 KT ARE EXPECTED.
MDB
FROM 12Z...
A WEAK SHORTWAVE MOVING ACROSS THE AREA COMBINED WITH WARM
ADVECTION HAS GENERATED SOME ISOLATED SHOWERS ACROSS THE REGION.
HOWEVER...THE STRONGEST FOCUS WILL ALIGN FROM NERN IOWA INTO
CENTRAL WISCONSIN...AND GENERALLY NORTH OF THE WISCONSIN BORDER.
HOWEVER...LATEST RADAR AND SATELLITE IMAGERY HAS INDICATED SOME
DEVELOPMENT OVER THE RFD AREA...SO...WILL KEEP SOME MENTION OF
PCPN IN THE FORECAST FOR THE RFD TERMINAL. OTHERWISE...EXPECT THE
REMAINDER OF THE TERMINALS TO REMAIN DRY TODAY. THERE WILL BE
ANOTHER CHANCE FOR SOME PCPN EARLY TOMORROW MORNING AS ANOTHER
SHORTWAVE CROSSES THE AREA...HOWEVER...THE GUIDANCE HAS NOT BEEN
VERY CONSISTENT IN THE THIS PCPN SIGNAL...SO CONFIDENCE IS LOW
THAT THE TERMINALS WILL BE DIRECTLY IMPACTED.
THE OTHER MAIN CONCERN FOR TODAY WILL BE WINDS. AS A LARGE AREA OF
HIGH PRESSURE SLIDES OFF THE MID ATLANTIC COAST...AND A SFC LOW
DEVELOPS OVER THE NRN PLAINS...A SOUTHERLY GRADIENT WILL STRENGTHEN
THROUGH THE DAY. WINDS WILL START OUT SELY THIS MORNING...BUT AS A
WEAK WARM FRONT LIFTS NWD...WINDS WILL VEER TO SLY AND STRENGTHEN
TO 10-12KT SUSTAINED. THROUGH THE MORNING...BREAKS IN THE
CLOUDINESS WILL ALLOW FOR SOME SUNSHINE AND INCREASED LOW LEVEL
MIXING AND STRONGER WINDS SHOULD BE ABLE TO MIX DOWN TO THE
SURFACE. LATEST SOUNDINGS SUGGEST THAT GUSTS SHOULD INCREASE FROM
LATE MORNING INTO THE AFTERNOON...WITH PEAK GUSTS TO ARND 20KT
THIS AFTERNOON.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* HIGH CONFIDENCE IN SSW WINDS WITH OCCASIONAL GUSTS.
* MEDIUM CONFIDENCE THAT BULK OF TSRA TO THE WEST NOW WILL PASS NW
OF THE TERMINALS...MEDIUM CONFIDENCE THAT SPOTTY ACTIVITY MAY
OCCUR IN THE CHI AREA...AND MEDIUM-HIGH CONFIDENCE IN TIMING OF
POTENTIAL.
* MEDIUM CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY MORNING IS
LOW.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.
FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.
SATURDAY THROUGH TUESDAY...VFR. WX NIL.
KREIN
&&
.MARINE...
255 AM CDT
A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
225 PM EDT WED SEP 18 2013
.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 330 AM EDT WED SEP 18 2013
A COLD FRONT WILL DROP SOUTHEAST ACROSS CENTRAL INDIANA FRIDAY
NIGHT. THE FRONT WILL INTERACT WITH WARM...MOIST AND UNSTABLE AIR
WHICH WILL RESULT IN THUNDERSTORM CHANCES STARTING TODAY. THE BEST
CHANCES WILL BE FRIDAY AND FRIDAY NIGHT AS THE FRONT GETS CLOSER.
THE SOUTHERLY FLOW WILL ALSO RESULT IN ABOVE NORMAL
TEMPERATURES...MOSTLY IN THE 80S. THEN...DRY WEATHER WILL RETURN BY
SATURDAY AS HIGH PRESSURE SETTLES EAST ACROSS THE GREAT LAKES WITH
COOLER TEMPERATURES IN THE 70S FOR AFTERNOON HIGHS.
&&
.NEAR TERM /TODAY/...
ISSUED AT 942 AM EDT WED SEP 18 2013
INTRODUCED LIKELIES INTO THE SOUTHWESTERN FORECAST AREA THROUGH
MIDDAY FOR THE AREA OF SHOWERS PUSHING INTO THAT AREA. HRRR TAKES
THIS THROUGH THE SOUTHWEST/SOUTH CENTRAL AREA AS IT WEAKENS LATER
THIS MORNING. AT LEAST A STRIKE OR TWO DETECTED SO WILL CONTINUE
ISOLATED THUNDER MENTION. ALSO REDUCED MAX TEMPS IN THAT AREA
OWING TO INFLUENCE OF RAIN COOLED AIR DURING WHAT WOULD ORDINARILY
BE BEST TIME FOR HEATING. PREVIOUS DISCUSSION FOLLOWS.
ISSUED AT 330 AM EDT WED SEP 18 2013
MAIN FOCUS TODAY WILL BE ON POPS. RADAR WAS SHOWING A GROUP OF
SHOWERS MOVING EAST AND NORTHEAST ACROSS NORTHWESTERN INDIANA AND
ARE ASSOCIATED WITH A WEAK WAVE ALOFT IN OTHERWISE MODEST ZONAL
FLOW. IN ADDITION...THERE WAS SOME ACTIVITY ACROSS SOUTHERN ILLINOIS
AND ALSO NEAR ST. LOUIS ASSOCIATED WITH ANOTHER WEAK WAVE THAT WILL
MOVE EAST ACROSS SOUTH CENTRAL INDIANA THIS MORNING. WEAK ISENTROPIC
LIFT WILL CONTINUE ALL THE WHILE...AND MODEL SOUNDINGS WERE
INDICATING DEEPENING MOISTURE. THE 05Z RAPID REFRESH WAS GOING
BONKERS WITH WIDESPREAD RAIN THIS MORNING...BLOWING UP THE SOUTHERN
ILLINOIS SHOWERS. THAT BEING SAID...DID RAISE POPS TO 30 PERCENT OR
MORE EXCEPT ACROSS OUR FAR EAST DO MAINLY TO RADAR TRENDS.
INSTABILITY IS PROGGED TO BE WEAK OR ABSENT TODAY...SO ONLY
MENTIONED ISOLATED THUNDER.
SHOULD BE DECENT CLOUD COVER TODAY...SO PREFER AT OR BELOW CONSALL
AND ALLBLEND.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
ISSUED AT 330 AM EDT WED SEP 18 2013
FOCUS WILL CONTINUE TO BE ON POPS THROUGH THE ENTIRE SHORT TERM.
MODELS ARE SIMILAR IN BRINGING A COLD FRONT SOUTHEAST ACROSS CENTRAL
INDIANA FRIDAY NIGHT AS A VIGOROUS UPPER TROUGH PROGRESSES EAST
ACROSS SOUTHERN CANADA. UPPER RIDGE WILL SETTLE ACROSS CENTRAL
INDIANA THURSDAY...WITH RETURN FLOW ACROSS THE OHIO VALLEY AROUND
EAST COAST HIGH PRESSURE. THIS WILL RESULT A VERY UNSTABLE
ATMOSPHERE ON THURSDAY WITH CAPES ABOVE 2000 J/KG. STILL...PLENTY OF
INSTABILITY THROUGH THE ENTIRE EXTENDED FOR THUNDER. WITH ONLY WEAK
SYNOPTIC FORCING...WILL ONLY GO WITH SMALL POPS UNTIL FRIDAY AFTER
THE UPPER RIDGE PASSES AND THE COLD FRONT AND UPPER TROUGH GET
CLOSER. THEN...LIKELY POPS FROM CONSALL...ALLBLEND AND MOS BLEND
LOOK GOOD AS MODEL UPWARD VERTICAL MOTION AND QPF PROGS SUGGEST
LINEAR CONVECTION LATE FRIDAY AFTERNOON AND NIGHT. WOULD NOT RULE
OUT STRONG OR EVEN ISOLATED SEVERE STORMS AS FRIDAY AND FRIDAY NIGHT.
TEMPERATURES WITH THE CLOUD COVER WILL BE TRICKY...BUT OVERALL ALL
BLEND LOOKS DECENT AND MATCHES UP WELL WITH ADJACENT OFFICES.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
ISSUED AT 220 PM EDT WED SEP 18 2013
DRY FORECAST THIS PERIOD WITH SEASONABLE TEMPERATURES.
GFS AND ECMWF DEPICT A CUT OFF UPPER LOW MOVING THROUGH THE
APPALACHIANS EARLY IN THE PERIOD WHILE RIDGING ALOFT AND STRONG
SUBSIDENCE OVER THE MISSISSIPPI RIVER VALLEY PROVIDES A NORTHERLY
FLOW OF AIR AS IT SLOWLY BUILDS EAST DURING THE PERIOD.
AS THE RIDGE MOVES EAST OVER INDIANA BY THE MIDDLE OF NEXT
WEEK...TEMPS WILL SLOWLY MODERATE TO SLIGHTLY ABOVE NORMAL AS
RETURN FLOW BEGINS.
&&
.AVIATION /DISCUSSION FOR THE 181800Z TAFS/...
ISSUED AT 1223 PM EDT WED SEP 18 2013
VFR CONDITIONS EXPECTED THIS AFTERNOON AND EVENING. MVFR TO IFR
CONDITIONS WILL BE POSSIBLE LATE TONIGHT. A RETURN TO VFR IS
EXPECTED LATE ON THURSDAY MORNING.
ACTIVE WEATHER PATTERN IS EXPECTED TO CONTINUE FOR THE NEXT 24
HOURS AS A WEAK RIDGE ALOFT ALLOWS SEVERAL WEAK...ILL-DEFINED SHORT
WAVES TO PASS ACROSS THE TAF SITES. FORECAST SOUNDINGS SHOW
LIMITED INSTABILITY...HOWEVER THE LOWER LEVELS SHOW AMPLE
MOISTURE. FURTHERMORE BROAD ISENTROPIC LIFT REMAINS IN PLACE
ACROSS THE REGION...PROVIDING HINTS OF LIFT. HOWEVER...NO ONE
FEATURE IS PREVALENT ENOUGH TO GRAB ONTO TO TIME ANY PRECIP MENTION.
THUS BASED UPON RADAR TRENDS...ISOLATED SHRA/TSRA OVER ILLINOIS
MAY REACH HUF AND BMG THIS AFTERNOON...HOWEVER AS HEATING IS LOST
THIS EVENING...OVERALL COVERAGE OF PRECIPITATION SHOULD DIMINISH.
MODELS HINT AT LOWERING CIGS AND VISIBILITIES DIURNALLY TONIGHT
AS HIGH DEW POINTS AND DIURNAL COOLING IS ONGOING. MODELS ONCE
AGAIN HINT AT ANOTHER BIT OF LIFT PUSHING THROUGH THE AREA ON LATE
THURSDAY MORNING...HOWEVER...CONFIDENCE IN THESE WEAK FEATURES
REMAIN LOW.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MK
NEAR TERM...MK/NIELD
SHORT TERM...MK
LONG TERM....PUMA
AVIATION...JP
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
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AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1234 PM EDT WED SEP 18 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 330 AM EDT WED SEP 18 2013
A COLD FRONT WILL DROP SOUTHEAST ACROSS CENTRAL INDIANA FRIDAY
NIGHT. THE FRONT WILL INTERACT WITH WARM...MOIST AND UNSTABLE AIR
WHICH WILL RESULT IN THUNDERSTORM CHANCES STARTING TODAY. THE BEST
CHANCES WILL BE FRIDAY AND FRIDAY NIGHT AS THE FRONT GETS CLOSER.
THE SOUTHERLY FLOW WILL ALSO RESULT IN ABOVE NORMAL
TEMPERATURES...MOSTLY IN THE 80S. THEN...DRY WEATHER WILL RETURN BY
SATURDAY AS HIGH PRESSURE SETTLES EAST ACROSS THE GREAT LAKES WITH
COOLER TEMPERATURES IN THE 70S FOR AFTERNOON HIGHS.
&&
.NEAR TERM /TODAY/...
ISSUED AT 942 AM EDT WED SEP 18 2013
INTRODUCED LIKELIES INTO THE SOUTHWESTERN FORECAST AREA THROUGH
MIDDAY FOR THE AREA OF SHOWERS PUSHING INTO THAT AREA. HRRR TAKES
THIS THROUGH THE SOUTHWEST/SOUTH CENTRAL AREA AS IT WEAKENS LATER
THIS MORNING. AT LEAST A STRIKE OR TWO DETECTED SO WILL CONTINUE
ISOLATED THUNDER MENTION. ALSO REDUCED MAX TEMPS IN THAT AREA
OWING TO INFLUENCE OF RAIN COOLED AIR DURING WHAT WOULD ORDINARILY
BE BEST TIME FOR HEATING. PREVIOUS DISCUSSION FOLLOWS.
ISSUED AT 330 AM EDT WED SEP 18 2013
MAIN FOCUS TODAY WILL BE ON POPS. RADAR WAS SHOWING A GROUP OF
SHOWERS MOVING EAST AND NORTHEAST ACROSS NORTHWESTERN INDIANA AND
ARE ASSOCIATED WITH A WEAK WAVE ALOFT IN OTHERWISE MODEST ZONAL
FLOW. IN ADDITION...THERE WAS SOME ACTIVITY ACROSS SOUTHERN ILLINOIS
AND ALSO NEAR ST. LOUIS ASSOCIATED WITH ANOTHER WEAK WAVE THAT WILL
MOVE EAST ACROSS SOUTH CENTRAL INDIANA THIS MORNING. WEAK ISENTROPIC
LIFT WILL CONTINUE ALL THE WHILE...AND MODEL SOUNDINGS WERE
INDICATING DEEPENING MOISTURE. THE 05Z RAPID REFRESH WAS GOING
BONKERS WITH WIDESPREAD RAIN THIS MORNING...BLOWING UP THE SOUTHERN
ILLINOIS SHOWERS. THAT BEING SAID...DID RAISE POPS TO 30 PERCENT OR
MORE EXCEPT ACROSS OUR FAR EAST DO MAINLY TO RADAR TRENDS.
INSTABILITY IS PROGGED TO BE WEAK OR ABSENT TODAY...SO ONLY
MENTIONED ISOLATED THUNDER.
SHOULD BE DECENT CLOUD COVER TODAY...SO PREFER AT OR BELOW CONSALL
AND ALLBLEND.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
ISSUED AT 330 AM EDT WED SEP 18 2013
FOCUS WILL CONTINUE TO BE ON POPS THROUGH THE ENTIRE SHORT TERM.
MODELS ARE SIMILAR IN BRINGING A COLD FRONT SOUTHEAST ACROSS CENTRAL
INDIANA FRIDAY NIGHT AS A VIGOROUS UPPER TROUGH PROGRESSES EAST
ACROSS SOUTHERN CANADA. UPPER RIDGE WILL SETTLE ACROSS CENTRAL
INDIANA THURSDAY...WITH RETURN FLOW ACROSS THE OHIO VALLEY AROUND
EAST COAST HIGH PRESSURE. THIS WILL RESULT A VERY UNSTABLE
ATMOSPHERE ON THURSDAY WITH CAPES ABOVE 2000 J/KG. STILL...PLENTY OF
INSTABILITY THROUGH THE ENTIRE EXTENDED FOR THUNDER. WITH ONLY WEAK
SYNOPTIC FORCING...WILL ONLY GO WITH SMALL POPS UNTIL FRIDAY AFTER
THE UPPER RIDGE PASSES AND THE COLD FRONT AND UPPER TROUGH GET
CLOSER. THEN...LIKELY POPS FROM CONSALL...ALLBLEND AND MOS BLEND
LOOK GOOD AS MODEL UPWARD VERTICAL MOTION AND QPF PROGS SUGGEST
LINEAR CONVECTION LATE FRIDAY AFTERNOON AND NIGHT. WOULD NOT RULE
OUT STRONG OR EVEN ISOLATED SEVERE STORMS AS FRIDAY AND FRIDAY NIGHT.
TEMPERATURES WITH THE CLOUD COVER WILL BE TRICKY...BUT OVERALL ALL
BLEND LOOKS DECENT AND MATCHES UP WELL WITH ADJACENT OFFICES.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
ISSUED AT 330 AM EDT WED SEP 18 2013
ENSEMBLES INDICATE A RATHER STRONG UPPER TROUGH WILL BE MOVING
THROUGH THE GREAT LAKES ON SATURDAY. ALTHOUGH IT APPEARS THAT THE
ASSOCIATED COLD FRONT WILL BE EAST OF THE AREA BY SATURDAY...SEVERAL
ENSEMBLES CUTOFF THE SOUTHERN PORTION OF THE TROUGH OVER THE OHIO
VALLEY ON SATURDAY...WITH THIS CUTOFF EVENTUALLY SINKING INTO THE
SOUTHEAST PORTIONS OF THE COUNTRY BY EARLY NEXT WEEK. THIS MAY
PROLONG THE PRECIPITATION THREAT INTO SATURDAY. WILL GO WITH CHANCE
POPS ON SATURDAY TO COVER THIS.
OTHERWISE...UPPER RIDGING EXPECTED TO BUILD ACROSS THE AREA THROUGH
THE MIDDLE OF NEXT WEEK AS LONG WAVE TROUGHING DEVELOPS OVER THE
WEST. WILL GO DRY AFTER SATURDAY.
&&
.AVIATION /DISCUSSION FOR THE 181800Z TAFS/...
ISSUED AT 1223 PM EDT WED SEP 18 2013
VFR CONDITIONS EXPECTED THIS AFTERNOON AND EVENING. MVFR TO IFR
CONDITIONS WILL BE POSSIBLE LATE TONIGHT. A RETURN TO VFR IS
EXPECTED LATE ON THURSDAY MORNING.
ACTIVE WEATHER PATTERN IS EXPECTED TO CONTINUE FOR THE NEXT 24
HOURS AS A WEAK RIDGE ALOFT ALLOWS SEVERAL WEAK...ILL-DEFINED SHORT
WAVES TO PASS ACROSS THE TAF SITES. FORECAST SOUNDINGS SHOW
LIMITED INSTABILITY...HOWEVER THE LOWER LEVELS SHOW AMPLE
MOISTURE. FURTHERMORE BROAD ISENTROPIC LIFT REMAINS IN PLACE
ACROSS THE REGION...PROVIDING HINTS OF LIFT. HOWEVER...NO ONE
FEATURE IS PREVALENT ENOUGH TO GRAB ONTO TO TIME ANY PRECIP MENTION.
THUS BASED UPON RADAR TRENDS...ISOLATED SHRA/TSRA OVER ILLINOIS
MAY REACH HUF AND BMG THIS AFTERNOON...HOWEVER AS HEATING IS LOST
THIS EVENING...OVERALL COVERAGE OF PRECIPITATION SHOULD DIMINISH.
MODELS HINT AT LOWERING CIGS AND VISIBILITIES DIURNALLY TONIGHT
AS HIGH DEW POINTS AND DIURNAL COOLING IS ONGOING. MODELS ONCE
AGAIN HINT AT ANOTHER BIT OF LIFT PUSHING THROUGH THE AREA ON LATE
THURSDAY MORNING...HOWEVER...CONFIDENCE IN THESE WEAK FEATURES
REMAIN LOW.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MK
NEAR TERM...MK/NIELD
SHORT TERM...MK
LONG TERM....JAS
AVIATION...JP
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AREA FORECAST DISCUSSION
NWS PADUCAH KY
230 PM CDT Wed Sep 18 2013
.SHORT TERM /Tonight through Friday night/...
ISSUED AT 230 PM CDT WED SEP 18 2013
The showers and isolated thunderstorms that occurred this morning
have all but dissipated by mid afternoon. Partial clearing will
continue to spread slowly east. The trend toward low and mid level
drying is indicated by RAP and nam model soundings. This drying
appears to be in response to a gradual rebuilding of the 500 mb
ridge that was flattened by a weak impulse this morning.
Through Thursday...the mid level ridge will continue to slowly build
over our region. This should continue to suppress most convection
over the Lower Ohio and Mid Mississippi Valleys. Will keep slight
chance pops during the peak heating hours from roughly 18z to 00z to
account for isolated diurnally driven storms.
A rather strong cold front will approach from the northwest on
Thursday night...reaching southern Illinois and southeast Missouri
on Friday. The front will continue moving southeast across western
Kentucky and southwest Indiana on Friday evening. The 09z sref
timing looks reasonable. A deepening upper trough will enhance lift
along the frontal zone...and deep layer moisture will be high for
this time of year /sref precip water values about 1.9 inches/. Looks
like the first widespread significant rainfall of the month will
occur. Storm total qpf should be at least one half inch...with some
1 inch amounts likely in heavier convection. Severe weather
potential will depend on how much sunshine and diurnal heating takes
place ahead of the front. Isolated severe convection is currently
forecast by SPC /see day 3 outlook/.
South to southwest low level flow will keep unseasonably warm and
humid conditions in place through Friday. The nam continues to have
problems with too much moisture in the model...as shown in its high
pops and abundant cloudiness. The warmer gfs mos highs look better
for Thursday.
.LONG TERM /Saturday through Wednesday/...
ISSUED AT 230 PM CDT WED SEP 18 2013
Main issue in the extended looks to be with how quickly an upper
level trof will move east out of the region over the weekend. Models
seem to be trending toward a less progressive solution in this
respect. Both the operational GFS and ECMWF not suggest showers will
linger into Saturday along and south of the Ohio River, east of the
H50 trof axis. Will bump up precip chances on Sat into the 40 to 50
percent range over much of the Pennyrile region of western KY.
Otherwise, the most noticeable change over the weekend will be
another transition to much cooler and less humid conditions. Highs
both Saturday and Sunday will likely stay down in the 70s, with lows
Sat night mostly in the 50 to 55 degree range.
As we head into next week, it now appears as though an Omega
Blocking pattern will become established along the MS River Valley.
This should keep things quite dry across our region, with sunny,
warm afternoons and cool nights. Temperatures will warm a touch each
day, and most locations will likely be back into the middle 80s by
Wednesday afternoon. Humidity levels should stay low though.
&&
.AVIATION...
ISSUED AT 1237 PM CDT WED SEP 18 2013
A weak disturbance in the mid levels of the atmosphere will progress
east of the region this afternoon. In the wake of the
disturbance...clearing has occurred over se Missouri. This clearing
will spread across the kpah area early this afternoon. Where rain
saturated the low levels this morning around kevv and kowb...mvfr
cigs are likely to persist most or all afternoon. All sites will
lose their low clouds around sunset. Mainly just mid level clouds
are forecast for the remainder of the taf period. Winds will remain
around 5 knots all night...which should preclude vsby problems due
to haze or fog.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
SHORT TERM...MY
LONG TERM...GM
AVIATION...MY
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
243 PM EDT WED SEP 18 2013
LATEST UPDATE...
LONG TERM
.SYNOPSIS...
ISSUED AT 148 PM EDT WED SEP 18 2013
A WARM FRONT WILL PUSH NORTHWARD THROUGH LOWER MICHIGAN TONIGHT
LEADING TO SOME SHOWERS AND THUNDERSTORMS. SOUTHWEST WINDS WILL
INCREASE THURSDAY ALLOWING FOR AND UNSEASONABLY WARM DAY. MOISTURE
FROM THE GULF OF MEXICO WILL STREAM INTO THE AREA THURSDAY NIGHT
AND EARLY FRIDAY AHEAD OF A COLD FRONT. AS THIS FRONT PUSHES
THROUGH THE REGION FRIDAY...A PERIOD OF SHOWERS AND THUNDERSTORMS
CAN BE EXPECTED.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 148 PM EDT WED SEP 18 2013
THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE TIMING AND
STRENGTH OF THE CONVECTION. STORMS IN NW ILLINOIS ARE SHOWN TO
WEAKEN AS THEY HEAD TOWARD CHICAGO THIS AFTERNOON. HRRR SHOWS
CONVECTION REDEVELOPING OVER LAKE MI LATER TONIGHT AND MOVING INTO
THE HOLLAND TO MUSKEGON REGION. THIS MAKES SENSE WITH A
STRENGTHENING LOW LEVEL JET ACCOMPANYING THE WARM FRONT THAT
FEATURES ELEVATED INSTABILITY. NOT ALL MODELS HAVE THIS...BUT THE
HRRR TENDS TO HANDLE THE CONVECTION BETTER THAN MOST. WILL
DECREASE POPS INLAND TONIGHT...BUT CLOSER TO LAKE MI WILL KEEP THE
LIKELY VALUES GOING. SEVERE WEATHER IS NOT FORECASTED...BUT
PERHAPS A HEAVY RAIN THREAT MAY EXIST.
A LULL IN THE CONVECTION IS EXPECTED THU AS NO FOCUSING MECHANISM
IS SHOWN. IT WILL BE A WARM AND INCREASINGLY HUMID. IT DOES BECOME
RATHER UNSTABLE...SO WILL HOLD ONTO A LOW POP FOR STORMS.
I RAISED POPS FOR FRIDAY. WITH PWAT VALUES APPROACHING 2 INCHES
AND A FRONT PRESSING IN ALONG WITH LIFT...IT SHOULD BE RATHER WET
AT TIMES. MODELS HAVE TRENDED SOMEWHAT FASTER WITH THE FRONT...SO
WE MAY BE ABLE TO START DRYING THINGS OUT FROM THE WEST BEFORE THE
END OF THE DAY. WILL WAIT TO SEE IF THIS TREND PERSIST BEFORE
CHANGING FRIDAYS FORECAST. I DID LOWER POPS FOR FRIDAY NIGHT
BECAUSE OF THIS. AS FOR SEVERE WEATHER...THE STRONGER DEEP LAYER
SHEAR IS SHOWN TO LAG BEHIND THE COLD FRONT...SO SOMEWHAT OF A
LIMITED RISK. STILL WITH BETTER INSTABILITY DEVELOPING AND
INCREASING WIND FIELDS ALONG WITH A LOW LEVEL JET MOVING IN AND
STRENGTHENING...A RISK STILL EXISTS. WILL NEED TO MONITOR TRENDS
CLOSELY IN THE COMING DAYS.
.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 243 PM EDT WED SEP 18 2013
AN UNEVENTFUL PERIOD IS EXCEPTED FOR THIS WEEKEND AND INTO THE
FIRST HALF OF NEXT WEEK. HIGH PRESSURE OVER THE UPPER MIDWEST ON
SATURDAY WILL SLOWLY MOVE OVER THE GREAT LAKES BY LATE IN THE
WEEKEND. THIS HIGH WILL BE STALLED OVER THE AREA AS A STORM SYSTEM
MOVES UP THE EAST COAST THROUGH THE FIRST HALF OF THE WORK WEEK.
SO FAIR WEATHER SHOULD PREVAIL.
LOWERED TEMPS A BIT FOR SATURDAY AND SUNDAY AS WE WILL BE UNDER A
THERMAL TROUGH . BOTH DAYS SHOULD SEE HIGHS STAYING IN THE 60S. WE
SHOULD SEE A WARM UP INTO THE WORK WEEK. HOWEVER LOW LEVEL FLOW
WILL BE FROM THE EAST OR SOUTHEAST...SO ANY MODERATION OF TEMPS
WILL BE GENTLE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 111 PM EDT WED SEP 18 2013
MAINLY VFR CONDITIONS ARE EXPECTED OVER THE NEXT 24 HOURS...
HOWEVER THERE COULD BE PATCHY AREAS OF FOG EARLY THU MORNING.
AS FOR THUNDERSTORM CHANCES...BELIEVE THEY WILL HOLD OFF UNTIL
AFTER 05Z THU...BUT COULD BE AROUND THROUGH 18Z THU. HOWEVER...
ALSO EXPECT THEY WILL REMAIN ISOLATED OR VERY WIDELY SCATTERED AND
SHOULD BE ABLE TO NAVIGATE AROUND THEM...AND ONLY BRIEFLY OVER
ANY ONE LOCATION. SEEMS AS THOU THE SOUTHERN TAF SITES...AZO...BTL
AND JXN...STAND A LONGER PERIOD OF POTENTIAL STORMS AS MOISTURE AND
LIFT ARE SLIGHTER MORE FAVORABLE THERE.
&&
.MARINE...
ISSUED AT 148 PM EDT WED SEP 18 2013
WINDS ARE FORECASTED TO BE STRONGER THU INTO THU NIGHT. MAY NEED
SMALL CRAFT AND BEACH HAZARDS TO COVER THIS. UNTIL THEN THE
SOUTHERLY FLOW WILL KEEP WAVES UP TO AROUND 2 TO 4
FEET...ESPECIALLY OFF OF LITTLE AND BIG SABLE POINTS.
&&
.HYDROLOGY...
ISSUED AT 148 PM EDT WED SEP 18 2013
LOCALIZED HEAVY RAIN WILL BE POSSIBLE WITH THE STORMS. TONIGHT AS
A LOW LEVEL JET MOVES IN PWAT VALUES CLIMB TO OVER 1.5 INCHES.
CORFIDI VECTORS SUGGESTS A LOCALIZED HEAVY RAIN THREAT MAY EXIST.
CURRENTLY IT APPEARS THAT AREAS ALONG THE LAKESHORE STAND THE
HIGHEST CHANCE FOR THE STORMS. A MORE WIDESPREAD ROUND OF STORMS
IS FORECASTED FOR THU NIGHT INTO FRI. PWAT VALUES LIKELY TO CLIMB
ABOVE 1.75 INCHES WITH ANOTHER LOW LEVEL JET PUSHING THROUGH.
CORFIDI VECTORS ALSO SUGGEST A HEAVY RAIN THREAT. HOW MUCH RAIN
FALLS WILL LIKELY DEPEND ON HOW EFFICIENT THE RAIN BECOMES AND HOW
THE CONVECTION EVOLVES. SUSPECT LOCALLY MORE THAN 2 INCHES WILL
FALL BY FRI NIGHT.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...JK
AVIATION...JK
HYDROLOGY...MJS
MARINE...MJS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
212 PM EDT WED SEP 18 2013
LATEST UPDATE...
SYNOPSIS/SHORT TERM/HYDRO/MARINE
.SYNOPSIS...
ISSUED AT 148 PM EDT WED SEP 18 2013
A WARM FRONT WILL PUSH NORTHWARD THROUGH LOWER MICHIGAN TONIGHT
LEADING TO SOME SHOWERS AND THUNDERSTORMS. SOUTHWEST WINDS WILL
INCREASE THURSDAY ALLOWING FOR AND UNSEASONABLY WARM DAY. MOISTURE
FROM THE GULF OF MEXICO WILL STREAM INTO THE AREA THURSDAY NIGHT
AND EARLY FRIDAY AHEAD OF A COLD FRONT. AS THIS FRONT PUSHES
THROUGH THE REGION FRIDAY...A PERIOD OF SHOWERS AND THUNDERSTORMS
CAN BE EXPECTED.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 148 PM EDT WED SEP 18 2013
THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE TIMING AND
STRENGTH OF THE CONVECTION. STORMS IN NW ILLINOIS ARE SHOWN TO
WEAKEN AS THEY HEAD TOWARD CHICAGO THIS AFTERNOON. HRRR SHOWS
CONVECTION REDEVELOPING OVER LAKE MI LATER TONIGHT AND MOVING INTO
THE HOLLAND TO MUSKEGON REGION. THIS MAKES SENSE WITH A
STRENGTHENING LOW LEVEL JET ACCOMPANYING THE WARM FRONT THAT
FEATURES ELEVATED INSTABILITY. NOT ALL MODELS HAVE THIS...BUT THE
HRRR TENDS TO HANDLE THE CONVECTION BETTER THAN MOST. WILL
DECREASE POPS INLAND TONIGHT...BUT CLOSER TO LAKE MI WILL KEEP THE
LIKELY VALUES GOING. SEVERE WEATHER IS NOT FORECASTED...BUT
PERHAPS A HEAVY RAIN THREAT MAY EXIST.
A LULL IN THE CONVECTION IS EXPECTED THU AS NO FOCUSING MECHANISM
IS SHOWN. IT WILL BE A WARM AND INCREASINGLY HUMID. IT DOES BECOME
RATHER UNSTABLE...SO WILL HOLD ONTO A LOW POP FOR STORMS.
I RAISED POPS FOR FRIDAY. WITH PWAT VALUES APPROACHING 2 INCHES
AND A FRONT PRESSING IN ALONG WITH LIFT...IT SHOULD BE RATHER WET
AT TIMES. MODELS HAVE TRENDED SOMEWHAT FASTER WITH THE FRONT...SO
WE MAY BE ABLE TO START DRYING THINGS OUT FROM THE WEST BEFORE THE
END OF THE DAY. WILL WAIT TO SEE IF THIS TREND PERSIST BEFORE
CHANGING FRIDAYS FORECAST. I DID LOWER POPS FOR FRIDAY NIGHT
BECAUSE OF THIS. AS FOR SEVERE WEATHER...THE STRONGER DEEP LAYER
SHEAR IS SHOWN TO LAG BEHIND THE COLD FRONT...SO SOMEWHAT OF A
LIMITED RISK. STILL WITH BETTER INSTABILITY DEVELOPING AND
INCREASING WIND FIELDS ALONG WITH A LOW LEVEL JET MOVING IN AND
STRENGTHENING...A RISK STILL EXISTS. WILL NEED TO MONITOR TRENDS
CLOSELY IN THE COMING DAYS.
.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 341 AM EDT WED SEP 18 2013
THE ONLY PRECIPITATION FORECAST IN THE LONG TERM COMES IN THE FIRST
FORECAST PERIOD...FRIDAY NIGHT. A COLD FRONT SHOULD TRAVERSE
SOUTHWEST LOWER MICHIGAN FRIDAY EVENING/NIGHT. SUBTLE TIMING
DIFFERENCES IN THE MODELS IN TERMS OF FRONTAL PASSAGE...BUT
EXPECT THE FRONT WILL BISECT THE FORECAST AREA FRIDAY EVENING.
MAINTAINED SHOWERS AND STORMS AHEAD OF THE FRONT...OR IN ALL AREAS
EXCEPT THE FAR NORTHWEST TOWARD PENTWATER AND LUDINGTON. HAVE LIKELY
CHANCES (60/70 PCT) FOR SHOWERS/STORMS IN THE SOUTHEAST TOWARDS
LANSING AND JACKSON AS THE FRONT SHOULD BE PUSHING INTO AN UNSTABLE
AIRMASS. OVERALL...FEEL THE GFS HAS BEEN VERY CONSISTENT IN TIMING
OF THE FRONT AND USED IT FOR GUIDANCE TONIGHT.
AFTER FRIDAY NIGHT...THE SATURDAY THROUGH TUESDAY PERIOD LOOKS VERY
UNEVENTFUL. SURFACE HIGH PRESSURE WILL BE SITUATED ACROSS THE REGION
THROUGH THIS TIME FRAME WITH DRY AIR AND MAINLY CLEAR SKIES
EXPECTED. HIGH TEMPERATURES OVER THE WEEKEND WILL BE SEASONABLE IN
THE 60S TO AROUND 70 DEGREES. HIGHS EARLY NEXT WEEK SHOULD WARM INTO
THE LOWER 70S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 111 PM EDT WED SEP 18 2013
MAINLY VFR CONDITIONS ARE EXPECTED OVER THE NEXT 24 HOURS...
HOWEVER THERE COULD BE PATCHY AREAS OF FOG EARLY THU MORNING.
AS FOR THUNDERSTORM CHANCES...BELIEVE THEY WILL HOLD OFF UNTIL
AFTER 05Z THU...BUT COULD BE AROUND THROUGH 18Z THU. HOWEVER...
ALSO EXPECT THEY WILL REMAIN ISOLATED OR VERY WIDELY SCATTERED AND
SHOULD BE ABLE TO NAVIGATE AROUND THEM...AND ONLY BRIEFLY OVER
ANY ONE LOCATION. SEEMS AS THOU THE SOUTHERN TAF SITES...AZO...BTL
AND JXN...STAND A LONGER PERIOD OF POTENTIAL STORMS AS MOISTURE AND
LIFT ARE SLIGHTER MORE FAVORABLE THERE.
&&
.MARINE...
ISSUED AT 148 PM EDT WED SEP 18 2013
WINDS ARE FORECASTED TO BE STRONGER THU INTO THU NIGHT. MAY NEED
SMALL CRAFT AND BEACH HAZARDS TO COVER THIS. UNTIL THEN THE
SOUTHERLY FLOW WILL KEEP WAVES UP TO AROUND 2 TO 4
FEET...ESPECIALLY OFF OF LITTLE AND BIG SABLE POINTS.
&&
.HYDROLOGY...
ISSUED AT 148 PM EDT WED SEP 18 2013
LOCALIZED HEAVY RAIN WILL BE POSSIBLE WITH THE STORMS. TONIGHT AS
A LOW LEVEL JET MOVES IN PWAT VALUES CLIMB TO OVER 1.5 INCHES.
CORFIDI VECTORS SUGGESTS A LOCALIZED HEAVY RAIN THREAT MAY EXIST.
CURRENTLY IT APPEARS THAT AREAS ALONG THE LAKESHORE STAND THE
HIGHEST CHANCE FOR THE STORMS. A MORE WIDESPREAD ROUND OF STORMS
IS FORECASTED FOR THU NIGHT INTO FRI. PWAT VALUES LIKELY TO CLIMB
ABOVE 1.75 INCHES WITH ANOTHER LOW LEVEL JET PUSHING THROUGH.
CORFIDI VECTORS ALSO SUGGEST A HEAVY RAIN THREAT. HOW MUCH RAIN
FALLS WILL LIKELY DEPEND ON HOW EFFICIENT THE RAIN BECOMES AND HOW
THE CONVECTION EVOLVES. SUSPECT LOCALLY MORE THAN 2 INCHES WILL
FALL BY FRI NIGHT.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...DUKE
AVIATION...JK
HYDROLOGY...MJS
MARINE...MJS
AREA FORECAST DISCUSSION
NWS DULUTH MN
307 PM CDT WED SEP 18 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 305 PM CDT WED SEP 18 2013
AT 300PM/2000Z...THERE WAS A POORLY DEFINED LOW PRESSURE SYSTEM IN
THE WESTERN DAKOTAS. A COLD FRONT STRETCHED FROM THE LOW INTO
WYOMING. A WARM FRONT STRETCHED FROM SE NORTH DAKOTA TO ILLINOIS.
MUCH OF THE NORTHLAND AND UPPER MIDWEST HAD CLOUDY TO MOSTLY
CLOUDY SKIES AHEAD OF THE LIFTING WARM FRONT...WHILE MUCH OF THE
NORTHERN AND CENTRAL PLAINS HAD SUNNY SKIES SOUTH AND WEST OF THE
WARM FRONT. TEMPERATURES ACROSS THE NORTHLAND RANGED FROM THE
UPPER 50S TO MID 60S...BUT AREAS JUST SOUTH AND WEST OF THE
APPROACHING HAD TEMPERATURES IN THE 80S. THERE WERE REPORTS OF FOG
AND DRIZZLE ALONG THE NORTH SHORE...WHILE OTHER PARTS OF THE
NORTHLAND HAD SOME REDUCED VISIBILITY FROM MIST.
TONIGHT...THE WARM FRONT WILL BEGIN TO LIFT INTO THE NORTHLAND
THIS EVENING...SO THERE MAY BE SOME INITIAL PARTIAL CLEARING IN
THE WESTERN AND SOUTHERN FORECAST AREA. HOWEVER...THE EASTERLY
FLOW OFF OF LAKE SUPERIOR WILL CONTINUE TO CAUSE PLENTY OF CLOUD
COVER FOR THE ARROWHEAD AND TWIN PORTS AREAS WITH DRIZZLE AND FOG.
THERE WILL BE AN INCREASING CHANCE OF SHOWERS AND THUNDERSTORMS
FROM THE WEST OVERNIGHT AS INSTABILITY AND MOISTURE TRANSPORT
INCREASES ACROSS THE NORTHLAND AND THE LOW PRESSURE SYSTEM AND
COLD FRONT MOVE INTO WESTERN MINNESOTA. THE MODELS ARE IN POOR
AGREEMENT...SO CONFIDENCE IS LOW. I DID NOT RAISE PCPN CHANCES
INTO THE LIKELY CATEGORY DUE TO THE UNCERTAINTY. IF STORMS DO
DEVELOP...THERE COULD BE A STRAY STRONG STORM ACROSS THE WESTERN
FORECAST AREA WITH SMALL HAIL AND GUSTY WINDS. THE EVENING SHIFT
WILL NEED TO LOOK INTO THE THREAT OF FOG FOR OTHER PARTS OF THE
FORECAST AREA. SOME MODELS ARE BEGINNING TO SUGGEST FOG...BUT FOR
NOW...I AM ASSUMING MORE WIDESPREAD REDUCED VISIBILITY FROM MIST.
THURSDAY...THE MODELS ARE IN A BIT BETTER AGREEMENT FOR
TOMORROW...BUT MY CONFIDENCE ON THE FORECAST IS STILL NOT AS MUCH
AS I WOULD LIKE TO HAVE AT LESS THAN 24 HOURS FROM THE FORECAST.
I GAVE INCREASING PCPN CHANCES TO THE CENTRAL AND EASTERN FORECAST
AREA DURING THE LATE MORNING AND AFTERNOON AS THE LOW PRESSURE
SYSTEM AND COLD FRONT MOVE THROUGH THE NORTHLAND. MOST OF THE
MODELS SHOW QUITE A BIT OF PCPN ACROSS THE EASTERN HALF OF THE
FORECAST AREA. THERE IS A MINOR THREAT OF STRONG TO SEVERE
STORMS...MAINLY ACROSS THE SOUTH CENTRAL AND SE FORECAST AREA
WHICH MAY NEAR THE WARM FRONT. IT LOOKS LIKE THERE COULD BE PLENTY
OF CAPE...MAYBE A COUPLE THOUSAND J/KG OR SO...BUT THAT THE BETTER
SHEAR WILL LAG WELL BEHIND THE CAPE. THEREFORE...THERE MAY BE A
LACK OF ORGANIZATION TO ANY STORMS THAT DO DEVELOP. I WOULD NOT BE
SURPRISED IF THERE ARE A FEW BRIEF STORMS WITH LARGE HAIL...GUSTY
WINDS...AND SHORT DOWNPOURS. HIGH TEMPERATURES ACROSS THE
NORTHLAND SHOULD BE IN THE MID TO UPPER 70S.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 305 PM CDT WED SEP 18 2013
SHOWERS AND STORMS SHOULD BE ONGOING THURSDAY EVENING AS THE FRONT
CONTINUES TO MOVE EAST THROUGH FAR EASTERN MINNESOTA AND
WISCONSIN/UPPER MICHIGAN. SOME OF THE STORMS COULD BE QUITE STRONG
OR SEVERE GIVEN STRENGTH OF THE FRONT AND INSTABILITY.
HOWEVER...SHEAR IS LACKING AND IS LARGELY BEHIND THE BOUNDARY AND
THAT COULD BE A LIMITING FACTOR. STRONG CAA WILL OCCUR BEHIND THE
FRONT AND THE UPPER TROUGH WILL MOVE OVER MINNESOTA BY 12Z FRIDAY.
COLD AIR ALOFT SHOULD LEAD TO A CHANCE FOR ADDITIONAL SHOWERS AND
CLOUDS LATE THURSDAY NIGHT INTO FRIDAY...MAINLY OVER NORTHERN
AREAS. 850MB TEMPS ARE FORECAST TO DROP TO 1-5C OVER THE CWA ON
FRIDAY. GUSTY WINDS WILL ALSO OCCUR BEHIND THE FRONT WITH THE CAA
AND PRESSURE RISES.
AN UPPER RIDGE WILL APPROACH THE CWA SATURDAY...MOVING OVER THE
CWA SUNDAY. A DRY PERIOD WILL OCCUR SATURDAY INTO SUNDAY. ANOTHER
SHORTWAVE WILL BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS EARLY
NEXT WEEK. AT THIS TIME...THIS FEATURE DOES NOT LOOK VERY STRONG.
HIGHS FRIDAY WILL ONLY RANGE FROM THE MIDDLE FIFTIES TO MIDDLE
SIXTIES BUT WILL WARM EACH DAY THROUGH WEDNESDAY WHICH SHOULD
FEATURE HIGHS IN THE UPPER SIXTIES TO MIDDLE SEVENTIES. A COUPLE
COLD NIGHTS ARE IN STORE FRIDAY NIGHT AND SATURDAY NIGHT...WITH
SATURDAY NIGHT LOOKING THE COLDEST. FROST OR A FREEZE WILL BE
POSSIBLE BOTH NIGHTS...ALTHOUGH THERE MAY BE TOO MUCH WIND FRIDAY
NIGHT. THE GRADIENT STARTS TO STRENGTHEN SATURDAY NIGHT...BUT WE
MAY BE ABLE TO DECOUPLE EARLY ENOUGH WITH CLEAR SKIES TO GET A
FREEZE/FROST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1243 PM CDT WED SEP 18 2013
IFR OR LOW MVFR CEILINGS/VSBYS COVERED THE NORTHLAND EARLY THIS
AFTERNOON WITH SOME DRIZZLE. CEILINGS/VSBYS WILL SLOWLY INCREASE
THROUGH THE AFTERNOON...BUT STILL REMAIN IFR/MVFR FOR MOST
AREAS. AREAS AROUND LAKE SUPERIOR WILL SEE THE LOWEST
CEILINGS/VSBYS AND THE BEST CHANCE FOR DRIZZLE. VISIBLE SATELLITE
IMAGERY SHOWED CLEARING OCCURRING ACROSS FAR SOUTHWEST MINNESOTA
AND THE RAP CONDENSATION PRESSURE DEFICITS WERE DOING A DECENT JOB
WITH THESE LOW CLOUDS. IT SUGGESTS THIS CLEARING WILL CONTINUE
NORTHEAST THIS AFTERNOON...AFFECTING KBRD LATE THIS
AFTERNOON/EARLY EVENING. CONFIDENCE IN THE CLEARING MAKING IT TOO
MUCH FURTHER NORTH AND EAST IS LOW...AND WE KEPT THE LOWER CLOUDS
IN THE REST OF THE TAFS...AND LOWERED VSBYS LATER THIS EVENING.
THE MOIST AIRMASS WILL REMAIN IN PLACE THROUGH THE PERIOD.
A COLD FRONT WILL INTO THE RED RIVER VALLEY LATE TONIGHT. SHOWERS
AND THUNDERSTORMS WILL BE POSSIBLE ALONG AND AHEAD OF THE FRONT
AND WE HIGHLIGHTED THE BEST CHANCE FOR THAT IN THE TAFS. SOME OF
THE STORMS COULD BE QUITE STRONG LATE TONIGHT INTO THURSDAY.
ADJUSTMENTS TO THE TIMING WILL LIKELY BE NEEDED LATER TONIGHT.
SOME OF THE CAMS SUGGEST THERE WILL BE A LINE THAT MOVES
THROUGH...WHICH WOULD BE A RELATIVELY SHORT DURATION EVENT...WHILE
THE DETERMINISTIC MODELS SUGGEST THE PRECIP WILL BE GREATER IN
COVERAGE AND LAST LONGER.
&&
.MARINE...
ISSUED AT 1243 PM CDT WED SEP 18 2013
WE UPDATED THE WINDS OVER LAKE SUPERIOR AND INCREASED THEM A BIT
MORE FROM ABOUT SILVER BAY TO THE TWIN PORTS TO PORT WING.
PRESSURE FALLS TO THE SOUTHWEST AND A TIGHTENING GRADIENT SHOULD
ALLOW WINDS TO PICK UP AND BE SUSTAINED AROUND 15 KNOTS LATER THIS
AFTERNOON INTO THE EVENING. WE KEPT WAVES FROM 2 TO 4 FEET...BUT
SMALL CRAFT ADVISORY THRESHOLDS MAY BE REACHED BRIEFLY LATE
TONIGHT INTO EARLY EVENING. WE`LL MONITOR WINDS/WAVES FROM THE
BUOYS/LAND OBS AND ADJUST AS NEEDED.
.PRELIMINARY POINT TEMPS/POPS...
DLH 60 73 52 60 / 50 70 50 20
INL 61 74 49 55 / 50 60 30 30
BRD 66 76 51 62 / 50 60 10 10
HYR 66 80 52 63 / 50 70 50 10
ASX 62 79 54 62 / 40 70 60 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...GROCHOCINSKI
LONG TERM...MELDE
AVIATION...MELDE
MARINE...MELDE
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
127 PM CDT WED SEP 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT WED SEP 18 2013
AN AREA OF LOW PRESSURE WAS LOCATED OVER THE WESTERN DAKOTAS...WITH
HIGH PRESSURE ACROSS THE EASTERN SEABOARD. THIS SETUP RESULTED IN
SOUTHERLY FLOW ACROSS THE UPPER MIDWEST WAS BRINGING WARM MOIST AIR
TO THE REGION. THIS WAA WAS EASILY IDENTIFIED BY LOOKING AT THE H850
TEMPERATURE ADVECTION OFF THE SPC MESOANALYSIS PAGE. THE LOW LEVEL
MOISTURE WAS EVIDENT BY THE STRATUS DECK THAT COVERED THE ENTIRE
UPPER MISSISSIPPI RIVER VALLEY WITH POCKETS OF DRIZZLE AND FOG. A
FEW AREAS OF ELEVATED CONVECTION MANAGED TO DEVELOP ALONG THE
EAST/WEST MUCAPE GRADIENT. SINCE THESE STORMS WERE ELEVATED...THEY
WERE UNABLE TO TAKE ADVANTAGE OF THE 0-1KM SHEAR AND HELICITY OF
30KTS AND 300M2/S2 RESPECTIVELY...AND DRIFTED HARMLESSLY EAST
NORTHEAST WITH THE MEAN WIND.
MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING HOW THE STATUS FIELD
WILL EVOLVE TODAY. H850 TEMPS WILL INCREASE FROM AROUND 12-15C EARLY
THIS MORNING...TO 20-22C THIS AFTERNOON. THAT WARM LAYER ALOFT WILL
ONLY ENHANCE THE CAPPING INVERSION AND LIMIT MIXING THIS AFTERNOON.
AS A RESULT IT MAY BE DIFFICULT TO LOOSE THE CLOUDS...WHICH IN TURN
WILL HAMPER TODAYS HIGH TEMPERATURES. MOST LIKELY IT WILL EITHER BE
BOOM OR BUST WITH HIGHS TODAY. THE NAM AND HRRR CLEAR OUT THE
CLOUDS BY EARLY THIS AFTERNOON WHICH WOULD FAVOR A WARMER SOLUTION.
HOWEVER...JUST WITHIN THE INDIVIDUAL MEMBERS OF THE SREF THE HIGH
TEMPERATURE TODAY VARIES FROM 89 TO 77 AT KMSP. MEMBER 2 OF THE
HOPWRF KEEPS THE CLOUDS ACROSS THE CWA THROUGH 21Z THIS
AFTERNOON...SO HAVE TRENDED BACK TEMPERATURES SLIGHTLY TO REFLECT
THE MORE CLOUDY SCENARIO. AS THE WARM FRONT LIFT NORTHWARD THIS
AFTERNOON AND OVERNIGHT PRECIP CHANCES WILL DECREASE FROM SOUTH TO
NORTH...BUT RETURN AGAIN EARLY THURSDAY MORNING AS THE COLD FRONT
APPROACHES FROM THE WEST.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 328 AM CDT WED SEP 18 2013
SHOWERS AND SOME THUNDERSTORMS WILL LIKELY BE ONGOING ACROSS THE
FAR EASTERN DAKOTAS AND WESTERN MINNESOTA THURSDAY MORNING. MOIST
SOUTHERLY FLOW WITH PW VALUES OF 1.5 TO 1.8 INCHES...ROUGHLY 220
PERCENT OF NORMAL...AND 850 MB TEMPS OF +20C WILL OVERSPREAD THE
REGION. THE CAPPING INVERSION PRODUCED BY THIS ABUNDANCE OF WARM
AIR ALOFT WILL LIKELY CONTRIBUTE TO CONSIDERABLE CLOUDINESS
THROUGH MUCH OF THE DAY WITH LITTLE HOPE OF DEEP MIXING AND
ERODING THE CAP SUFFICIENTLY AHEAD OF THE FRONT. THIS WILL PROVE
DETRIMENTAL ON WIDESPREAD CONVECTIVE CHANCES TO SOME
DEGREE...UNLESS SURFACE TEMPS DO WARM INTO THE 80S. BEST POTENTIAL
FOR THIS WOULD BE ACROSS WESTERN WI AS FROPA WILL TAKE PLACE LATE
IN THE DAY. MID LEVEL LAPSE RATES WILL CONTRIBUTE TO AROUND 2000
J/KG MLCAPE...SO IF THE CAP DOES ERODE...WIDESPREAD THUNDERSTORMS
CAN BE EXPECTED. MODEST SPEED SHEAR WOULD ALSO HELP ORGANIZE A FEW
STORMS ENOUGH FOR A MARGINAL SEVERE THREAT.
COOLER AND DRIER AIR WILL FOLLOW THURSDAY NIGHT INTO SATURDAY. AS
THE HIGH PUSHES OVERHEAD FRIDAY NIGHT...TEMPERATURES COULD FALL
INTO THE 30S IN SOME LOCATIONS IF WINDS DECOUPLE.
RETURN FLOW WILL COMMENCE SATURDAY NIGHT AND STRENGTHEN INTO EARLY
NEXT WEEK AS TROUGHING DIGS INTO THE PACIFIC NORTHWEST. SOUTHWEST
FLOW WILL KEEP THE STORM TRACK WEST OF THE REGION...AND COLD
FRONTS/DISTURBANCES PUSHING THROUGH WILL NOT HAVE MUCH PUNCH. ONE
SUCH FRONT IS PROGGED FOR MONDAY AND MONDAY NIGHT...WITH THE ECMWF
THE STRONGEST OF ALL GUIDANCE. ONLY LOW POPS WERE JUSTIFIED.
TEMPERATURES WILL BE ABOVE AVERAGE EARLY NEXT WEEK...AND 80S MAY
RETURN FOR MIDWEEK WITH 925 MB TEMPS CLIMBING INTO THE 20S C.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 125 PM CDT WED SEP 18 2013
AN ACTIVE PATTERN OVER THE NEXT 24 HOURS AS A WARM FRONT PASSES
ACROSS THE AREA THIS EVENING...FOLLOWED BY ITS ASSOCIATED COLD
FRONT DURG THE DAY TMRW. LOW LEVEL SE WINDS BECOME MORE SLY TNGT
BEHIND THE WMFNT...INVITING MORE LOW LEVEL MOISTURE AND WARM AIR
INTO THE AREA. THIS WILL AGAIN TRANSLATE TO CONDITIONS DROPPING TO
IFR...AND POSSIBLY LIFR OVERNIGHT THRU DAYBREAK TMRW. THE TIMING
OF THE DEGRADATION MAY EVEN OCCUR LATE THIS EVE AS HAPPENED YDA SO
CONDITIONS WILL CERTAINLY NEED TO BE MONITORED. AS THE CDFNT APCHS
TMRW MRNG...SHWRS WILL SPREAD S TO N AHEAD OF THE FNT INTO THE
REGION. THERE ARE SOME CONFLICTING SIGNALS AS TO THE POTENTIAL FOR
THUNDER...BUT TRYING TO PINPOINT IT TO A TERMINAL IS HIGHLY
PROBLEMATIC AND CONFIDENCE IS LOW SO HAVE OPTED TO OMIT ITS
MENTION ATTM BUT PARAMETERS ARE THERE FOR TSTM DEVELOPMENT. THE
COLD FROPA IS SHOWN WITH THE WIND SHIFT TO W-NW DURG THE DAY
TMRW...AND THIS WILL ALSO MAKE FOR IMPROVEMENT IN CONDITIONS. HOW
QUICK IS THE MAIN QUESTION. HAVE OPTED TO GO WITH A SLOWER
IMPROVEMENT AS IT WILL TAKE SOME TIME FOR DRIER AIR TO MOVE INTO
THE REGION EVEN WITH THE FROPA...SO CEILINGS UNDER 2000 FT ARE A
VIABLE POSSIBILITY FOR MOST IF NOT ALL TAF SITES THRU MIDDAY THU.
KMSP...STARTED OUT WITH 1200 FT CEILINGS BUT THERE IS A REASONABLE
CHC OF SEEING CIGS RISE TO VFR LEVELS LATE THIS AFTN. THIS IS
BEFORE CONDITIONS AGAIN BECOME SIGNIFICANTLY DEGRADED OVERNIGHT
THRU THE FIRST HALF OF THE DAY TMRW. WILL LOOK FOR CEILINGS TO
AGAIN DROP BELOW 1700 FT ARND MIDNIGHT...AND MAY WELL BE EARLIER
THAN THAT RATHER THAN LATER. CONDS THEN CONTINUE TO DETERIORATE
THRU THE OVERNIGHT HRS INTO DAYBREAK...ALONG WITH -RA MOVING INTO
THE AREA. NO INCLUSION OF TS ATTM BUT THAT MAY CHANGE WITH LATER
TAF ISSUANCES. -RA REMAINS OVER THE AREA THRU MIDDAY TMRW THEN
CONDS WILL SLOWLY IMPROVE TMRW AFTN.
/OUTLOOK FOR KMSP/
FRI...VFR. WINDS NW 15G25KT.
SAT...VFR. WINDS NW 5-10KT.
SUN...VFR. WINDS SE 15G20KT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...JRB
LONG TERM...BORGHOFF
AVIATION...JPC
AREA FORECAST DISCUSSION
NWS DULUTH MN
1244 PM CDT WED SEP 18 2013
.UPDATE...
ISSUED AT 1038 AM CDT WED SEP 18 2013
AT 1030AM/1530Z...THE NORTHLAND HAD CLOUDY SKIES AS A RESULT OF THE
SOUTHERLY SATURATED LOW LEVEL FLOW. THE NORTHLAND WAS COOL BUT
HUMID WITH CURRENT TEMPERATURES IN THE MID 50S TO LOW 60S WITH
GENERALLY LOW DEW POINT DEPRESSIONS. THERE WAS AN AREA OF
LINGERING SHOWERS AND STORMS NEAR AND SOUTH OF THE HAYWARD AND
PHILLIPS AREA...AND THIS WAS DUE TO LINGERING OVERNIGHT CONVECTION
IN THE AXIS OF HIGHER 850 HPA MOISTURE TRANSPORT. PARTS OF THE
NORTH SHORE HAD FOG...MAINLY DUE TO THE EASTERLY FLOW OFF THE
LAKE. THERE WERE REPORTS OF LIGHT RAIN AND DRIZZLE ACROSS THE
FORECAST AREA.
FORECASTING PCPN CHANCES AND WEATHER TYPE WILL BE DIFFICULT TODAY.
THE MODELS ARE IN SOMEWHAT POOR AGREEMENT UNTIL MORE SIGNIFICANT
PCPN LIKELY MOVES INTO THE WESTERN FORECAST AREA LATER TODAY WITH
THE APPROACHING COLD FRONT. I UPDATED THE FORECAST THROUGH THIS
AFTERNOON...FOCUSING ON THE LATEST TRENDS. I PROLONGED CLOUD COVER
TODAY...BUT HAVE SOME CLEARING HAPPENING FROM THE SW THIS
AFTERNOON AS A WARM FRONT BEGINS TO LIFT TOWARDS THE NORTHLAND. I
ADDED PATCHY DRIZZLE ACROSS THE NORTHLAND THROUGH 1 PM SINCE IT
SEEMS THIS REALLY LOW CLOUD COVER IS PRODUCING REPORTS OF LIGHT
RAIN OR DRIZZLE HERE AND THERE. I AM ASSUMING THERE WILL BE A
LITTLE LIFTING OF THE CEILINGS THIS AFTERNOON...BUT IF NOT
MUCH...I MIGHT NEED TO PROLONG THE PATCHY DRIZZLE. EXCEPT FOR THE
SE FORECAST...I KEPT THUNDER OUT OF THE FORECAST UNTIL VERY LATE
THIS AFTERNOON WHEN THE MODELS INDICATE HIGHER CAPE VALUES WILL
MOVE INTO THE FORECAST AREA WITH THE LIFTING WARM FRONT.
UPDATE ISSUED AT 717 AM CDT WED SEP 18 2013
UPDATED FOR AVIATION DISCUSSION.
&&
.SYNOPSIS...
ISSUED AT 320 AM CDT WED SEP 18 2013
WARM ADVECTION PATTERN CONTINUES ACROSS THE NRN PLAINS AND EAST
INTO THE WRN GT LAKES. ALOFT A WEAK WESTERLY FLOW STRETCHES FROM
THE DAKOTAS INTO THE GT LAKES. A VERY LARGE AREA OF STRATUS WITH
LIGHT RAIN/BR/FG HAS DEVELOPED ACROSS MOST OF THE UPPER MIDWEST.
LATEST SPC MESOANALYSIS SHOWS 85H MSTR TRANSPORT DIRECTED FROM
SWRN MN INTO THE ERN EDGE OF CWA.
&&
.SHORT TERM...(TODAY AND TONIGHT AND TOMORROW)
ISSUED AT 320 AM CDT WED SEP 18 2013
TODAY...TOUGH CALL ON ACTUAL PRECIP OCCURRENCE TODAY. GENERAL IDEA
IS THAT SOME LIGHT RAIN WILL OCCUR ACROSS THE SERN CWA THIS
MORNING. THIS IS ASSOCIATED WITH THE INITIAL 85H MSTR TRANSPORT
AXIS INDUCED BY PASSING SHORTWAVE TROF. AS THE DAY PROGRESSES THE
MID LVL RIDGE AMPLIFIES OVER THE CWA WITH 85H MSTR TRANSPORT
REFORMING SOUTH AND WEST OF CWA. WILL CARRY THE IDEA THAT LOW
CLOUDS WILL BE TOUGH TO SCOUR OUT COMPLETELY BASED ON FCST COND
PRESS DEFICITS FROM HI-RES MDLS. MDL SNDGS SUGGEST SOME ELEVATED
CAPE DEVELOPING LATER THIS MORNING AND LINGERING INTO THE AFTN.
WILL MENTION SLIGHT CHC OF TRW BUT CONFIDENCE NOT VERY HIGH AT THIS
POINT. MORNING BR/FG SHOULD GRADUALLY DECREASE EXCEPT NEAR LAKE
SUPERIOR WHERE HI-RES MDL SUGGEST ONSHORE FLOW WILL CREATE EXTENDED
PERIOD OF BR/FG ESPECIALLY NEAR TWIN PORTS WHERE LONGER NORTHEAST
FETCH INTO THE HEAD OF THE LAKE MAXIMIZES NEAR SFC SATURATION. MAX
TEMPS COULD BE TRICKY TODAY WITH EXTENSIVE CLOUD COVER AND
INCREASINGLY STRONGER NE WIND NEAR LAKE SUPERIOR.
TONIGHT...SFC WARM FRONT MOVES NORTH INTO SRN CWA BY MIDNIGHT AND
THEN TOWARDS IRON RANGE BY EARLY MORNING. BDRY MAY BE SLOWED DOWN
NEAR LAKE SUPERIOR WHERE MARINE LAYER REINFORCES COOL DOME NEAR
SFC. MDLS INDICATE AN ARE OF MID LVL WARMING MOVING INTO WRN/SRN
CWA WHICH MAY LIMIT CONVECTIVE DEVELOPMENT AHEAD OF APPROACHING
COLD FRONT.
TOMORROW...COLD FRONT WILL MOVE ACROSS THE CWA WITH INCREASING
POPS. SPC HAS SLIGHT RISK OF SVR OVER ERN WISC ZONES. HOWEVER SOME
INDICATIONS THAT ACTIVITY OF AN ELEVATED NATURE MAY BE QUITE
ROBUST FARTHER WEST TOWARDS TWIN PORTS/LOWER ST CROIX VALLEY
ALTHOUGH AT THIS TIME HIGHEST DEEP LAYER SHEAR IS LOCATED FARTHER
NORTH OF BEST INSTABILITY. GIVEN NATURE OF ANOMALOUS PWATS AND
FAIRLY SIGNIFICANT FORCING AHEAD/NEAR FRONTAL BDRY SHOULD SEE SOME
LOCALLY HEAVY RAINFALL TOTALS BY LATE THURSDAY.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 320 AM CDT WED SEP 18 2013
A STRONG COLD FRONT WILL MOVE THROUGH THURSDAY NIGHT...BRINGING
SHOWERS AND THUNDERSTORMS TO THE REGION. SPC HAS A SLIGHT RISK OF
SEVERE THUNDERSTORMS FOR EASTERN PORTIONS OF THE CWA...WHICH SOUNDS
REASONABLE GIVEN THE STRENGTH OF THE FRONT AND AVAILABLE MOISTURE.
STRONG CAA WILL PUSH ACROSS THE NORTHLAND BEHIND THE FRONT...WITH
SHOWERS AND THUNDERSTORMS GRADUALLY DIMINISHING FROM WEST TO EAST
THURSDAY NIGHT. WITH A THERMAL TROUGH ACROSS THE CWA ON FRIDAY...
WILL NEED TO HANG ON TO A SMALL CHANCE OF SHOWERS...ESPECIALLY IN
THE NORTH. THE BIG QUESTION IS THE NEXT CHANCE OF FROST. IT LOOKS
LIKE FRIDAY NIGHT WILL LIKELY SEE LINGERING CLOUD COVER AND SOME
WIND INTO THE NIGHT. A MUCH BETTER CHANCE WOULD BE ON SATURDAY
NIGHT...WITH HIGH PRESSURE ACROSS THE REGION. WAA ALREADY STARTS
DURING THE NIGHT...BUT AT LEAST THE ARROWHEAD AND NW WI SHOULD SEE A
CHANCE OF FROST AS SKIES CLEAR ON SATURDAY. WAA WILL BRING WARMER
AIR INTO THE REGION ON SUNDAY...BUT OVERALL IT LOOKS LIKE A
GENERALLY DRY WEEKEND. THE NEXT CHANCE OF PRECIPITATION WOULD ARRIVE
ON MONDAY WITH CHANCE POPS CONTINUING INTO MIDWEEK DUE TO WAA AND
MUCH WARMER AIR ACROSS THE REGION. HIGH TEMPERATURES FRIDAY AND
SATURDAY WILL RANGE FROM THE MID 50S NORTH TO THE MID 60S SOUTH.
HIGHS ON SUNDAY AND MONDAY WILL GENERALLY BE IN THE 60S...WITH HIGHS
ON TUESDAY AND WEDNESDAY BACK INTO THE 70S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1243 PM CDT WED SEP 18 2013
IFR OR LOW MVFR CEILINGS/VSBYS COVERED THE NORTHLAND EARLY THIS
AFTERNOON WITH SOME DRIZZLE. CEILINGS/VSBYS WILL SLOWLY INCREASE THROUGH
THE AFTERNOON...BUT STILL REMAIN IFR/MVFR FOR MOST AREAS. AREAS
AROUND LAKE SUPERIOR WILL SEE THE LOWEST CEILINGS/VSBYS AND THE
BEST CHANCE FOR DRIZZLE. VISIBLE SATELLITE IMAGERY SHOWED CLEARING
OCCURRING ACROSS FAR SOUTHWEST MINNESOTA AND THE RAP CONDENSATION
PRESSURE DEFICITS WERE DOING A DECENT JOB WITH THESE LOW CLOUDS.
IT SUGGESTS THIS CLEARING WILL CONTINUE NORTHEAST THIS
AFTERNOON...AFFECTING KBRD LATE THIS AFTERNOON/EARLY EVENING.
CONFIDENCE IN THE CLEARING MAKING IT TOO MUCH FURTHER NORTH AND
EAST IS LOW...AND WE KEPT THE LOWER CLOUDS IN THE REST OF THE
TAFS...AND LOWERED VSBYS LATER THIS EVENING. THE MOIST AIRMASS
WILL REMAIN IN PLACE THROUGH THE PERIOD.
A COLD FRONT WILL INTO THE RED RIVER VALLEY LATE TONIGHT. SHOWERS
AND THUNDERSTORMS WILL BE POSSIBLE ALONG AND AHEAD OF THE FRONT
AND WE HIGHLIGHTED THE BEST CHANCE FOR THAT IN THE TAFS. SOME OF
THE STORMS COULD BE QUITE STRONG LATE TONIGHT INTO THURSDAY. ADJUSTMENTS
TO THE TIMING WILL LIKELY BE NEEDED LATER TONIGHT. SOME OF THE
CAMS SUGGEST THERE WILL BE A LINE THAT MOVES THROUGH...WHICH WOULD
BE A RELATIVELY SHORT DURATION EVENT...WHILE THE DETERMINISTIC
MODELS SUGGEST THE PRECIP WILL BE GREATER IN COVERAGE AND LAST
LONGER.
&&
.MARINE...
ISSUED AT 1243 PM CDT WED SEP 18 2013
WE UPDATED THE WINDS OVER LAKE SUPERIOR AND INCREASED THEM A BIT
MORE FROM ABOUT SILVER BAY TO THE TWIN PORTS TO PORT WING.
PRESSURE FALLS TO THE SOUTHWEST AND A TIGHTENING GRADIENT SHOULD
ALLOW WINDS TO PICK UP AND BE SUSTAINED AROUND 15 KNOTS LATER THIS
AFTERNOON INTO THE EVENING. WE KEPT WAVES FROM 2 TO 4 FEET...BUT
SMALL CRAFT ADVISORY THRESHOLDS MAY BE REACHED BRIEFLY LATE
TONIGHT INTO EARLY EVENING. WE`LL MONITOR WINDS/WAVES FROM THE
BUOYS/LAND OBS AND ADJUST AS NEEDED.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 64 61 73 51 / 20 50 70 40
INL 71 61 72 48 / 20 50 70 40
BRD 74 64 74 50 / 20 40 60 10
HYR 71 63 77 51 / 30 40 70 50
ASX 68 60 78 53 / 20 40 70 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
UPDATE...GROCHOCINSKI
SYNOPSIS...CANNON
SHORT TERM...CANNON
LONG TERM...DAP
AVIATION...MELDE
MARINE...MELDE
AREA FORECAST DISCUSSION
NWS BILLINGS MT
1103 AM MDT WED SEP 18 2013
.UPDATE...
HAVE UPDATED AGAIN TO RAISE TEMPS PER PREFRONTAL WARMING AND
DOWNSLOPE WINDS. BAND OF SHOWERS FROM LVM TO 3HT HAS SLOWED IN
RESPONSE TO 95KT SWLY JET ALOFT. WATER VAPOR SHOWS DRY SLOTTING
INTO OUR BEARTOOTH FOOTHILLS...AND HAVE RAISED WIND GUSTS IN THIS
AREA AND OVER THE BIG HORNS FOR THE NEXT FEW HOURS. SOLAR HEATING
WILL HELP OUR CONVECTIVE CHANCES THIS AFTERNOON. TEMPS FALLING
SIGNIFICANTLY BEHIND COLD FRONT...LVM REACHED 62F BUT HAS SINCE
FALLEN TO 48F...SO HEADS UP EVERYONE. JKL
UPPER LOW CONTINUES TO APPROACH OUR REGION FROM THE WEST. 95KT H3
JET CURRENTLY LIFTING FROM SE ID INTO NW WY IS PROVIDING UPPER
SUPPORT...AND LINE OF SHOWERS WITH EMBEDDED TSTMS HAS FORMED ALONG
SFC FRONT IN SOUTH CENTRAL MT AND IS NEAR A 3HT TO LVM LINE AS OF
1530Z...MOVING SLOWLY EAST. HIGHWAY 212 HAS BEEN CLOSED OVER
BEARTOOTH PASS PER SOME WET SNOW OVER 9KFT OR SO. FISHER CK SNOTEL
AT 9100 FEET IS CURRENTLY 36F.
FORECAST IS ON TRACK AND HAVE MADE NO SIGNIFICANT CHANGES THIS
MORNING. EASTERN PARTS HAVE CLEARED SO HAVE REDUCED SKY COVER AND
POPS TIL 18Z...AND HAVE ALSO RAISED TEMPS A LITTLE PER THE SUN AND
WEST WINDS. MORNING DESTABILIZING SHOULD BE FOLLOWED BY SOME
STRONGER STORMS IN OUR EAST THIS AFTERNOON AS ASCENT INCREASES...
AND THIS INDEED IS WHAT THE LATEST HRRR IS HINTING AT. TSTMS WILL
BE MORE ISOLD WITH GENERALLY SHOWERY/COOLER WEATHER OUT WEST. 12Z
BOISE RAOB SHOWS 500MB OF -20C AND 700MB TEMP OF -5C...CONTINUING
THE TREND OF COLDER MID AND UPPER LEVEL TEMPS FURTHER SOUTH AS THE
TROF PUSHES THROUGH THE NORTHERN ROCKIES...AND THIS IS CONSISTENT
WITH A MORE AMPLIFIED UPPER JET. ALL THAT BEING SAID...SHOWER
ACTIVITY WILL CONTINUE THROUGH THE DAY AND INTO TONIGHT...WITH
SNOW LEVELS LIKELY TO DROP TO AROUND 8KFT. STRONGER DESCENT AND
LOW LEVEL DOWNSLOPE WINDS WILL REDUCE OUR PCPN CHANCES
SIGNIFICANTLY AFTER 00Z. HAVE RAISED WESTERN POPS THROUGH THE
AFTERNOON THOUGH BASED ON ASCENT...POST FRONTAL MOISTURE AND
COOLING ALOFT.
JKL
&&
.SHORT TERM...VALID FOR TDY AND THU...
PASSAGE OF THE LONG-ADVERTISED UPPER-LEVEL TROUGH IS STILL SET FOR
TODAY...BUT SOME UNCERTAINTY REMAINS IN PRECIPITATION COVERAGE. WE
HAVE MUCH MORE CONFIDENCE IN THE ARRIVAL OF COOL TEMPERATURES.
TODAY...FORCING FOR ASCENT SIMULATED BY MODEL 500-300 HPA Q-VECTOR
FIELDS IS BEING MANIFEST AS RAINFALL IN SOUTHEASTERN ID ALREADY AS
OF 09 UTC. WE EXPECT THAT VERTICAL MOTION AND PRECIPITATION TO GET
UP INTO SOUTH CENTRAL MT THIS MORNING...SO LIKELY POPS REMAIN FROM
COOKE CITY AND LIVINGSTON AND ALL THE WAY UP TO HARLOWTON. THAT IS
SUPPORTED BY ENSEMBLE OUTPUT INCLUDING THE 21 UTC SREF. CONFIDENCE
IS LOWER THAT ANYTHING MORE THAN SCATTERED SHOWERS WILL OCCUR EAST
OF THERE IN PLACES LIKE BILLINGS TODAY BECAUSE MODELS ALL SIMULATE
SUBSIDENCE FROM NEAR THE SURFACE TO 500 HPA...WITH DOWNSLOPE WINDS
AIDING THAT PROCESS BY AFTERNOON TOO. THE DOWNSLOPE SIGNATURE WILL
WEAKEN FROM BIG HORN COUNTY AND INTO SOUTHEASTERN MT...SO POPS ARE
HIGHER /IN THE 50 PERCENT RANGE/ THIS AFTERNOON IN THOSE AREAS. IT
LOOKS LIKE STORMS MAY ACTUALLY FIRE FROM BIG HORN COUNTY EAST OVER
INTO SOUTHEASTERN MT AFTER 18 UTC AS HEIGHT FALLS OCCUR ALOFT WITH
A MODERATELY UNSTABLE BOUNDARY LAYER. FORECAST SOUNDINGS IN PLACES
LIKE EKALAKA SHOW MLCAPE UP TO 800 J/KG AND 50 KT MID-LEVEL WINDS.
THUS...WE COULD ACTUALLY HAVE SOME STRONG STORMS OVER SOUTHEASTERN
MT THIS AFTERNOON AND EARLY EVENING. THAT IDEA IS SUPPORTED BY THE
00 UTC 4 KM WRF-NMM OUTPUT. OF COURSE...THAT BANKS ON SOME HEATING
OF THE BOUNDARY LAYER THAT IS NOT A GIVEN IF CLOUDS ARE TOO THICK.
IF CLOUDS DO NOT HINDER WARMING TOO MUCH...70S F ARE ATTAINABLE IN
SOUTHEASTERN MT. COLD AIR ADVECTION WILL BEGIN SOONER ACROSS SOUTH
CENTRAL MT...MAKING 60S F MORE COMMON THERE. ISOLATED THUNDERSTORM
WORDING IS STILL NEEDED EVEN WHERE IT WILL BE COOLER THOUGH DUE TO
SEASONABLY STEEP MID-LEVEL LAPSE RATES.
TONIGHT...WE HAVE AT LEAST LOW SHOWER CHANCES THIS EVENING FOR THE
ENTIRE AREA...AND LINGERING THUNDERSTORM CHANCES OVER SOUTHEASTERN
MT AS WELL. HOWEVER...A DRYING TREND WILL BE IN PLACE OVERNIGHT IN
MOST AREAS WITH ONLY WEAK LARGE-SCALE FORCING.
THU...COOL AND CYCLONIC LOW-LEVEL FLOW SHOULD YIELD QUITE A BIT IN
THE WAY OF STRATOCUMULUS CLOUD COVER ACROSS MOST OF THE AREA. THAT
WILL DO LITTLE TO HELP TEMPERATURES...WHICH SHOULD ONLY TOP OUT IN
THE 60S F IN THE LOWER ELEVATIONS. THE 00 UTC GUIDANCE ALL SHOWS A
MODEST SHORT WAVE TROUGH DROPPING INTO THE BACK SIDE OF THE LARGER
500-HPA TROUGH AND ACROSS SOUTHEASTERN MT DURING THE MORNING. THAT
SUPPORTS OUR PREVIOUSLY-ADVERTISED LOW SHOWER CHANCES IN THE MILES
CITY AND BAKER AREAS...BUT LATER FORECASTS MAY EVEN NEED A LOW POP
BEYOND 18 UTC FOR PARTS OF SOUTHEASTERN MT IF THE SHORT WAVE SLOWS
UP AT ALL. SCHULTZ
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
MODELS CONTINUE TO POINT TO A WARM AND DRY PERIOD FRIDAY THROUGH
SATURDAY AS AN AMPLIFIED RIDGE PREVAILS OVER THE ROCKIES AND HIGH
PLAINS. HOWEVER...ANOTHER TROUGH IS IN POSITION OVER THE PACIFIC
NORTHWEST BY SATURDAY EVENING TO INVADE THE NORTHERN ROCKIES. THIS
LOOKS LIKE A SPLIT FLOW TROUGH. AS SUCH...THE HIGH COUNTRY WILL
SEE THE BEST POPS WHILE LOWER ELEVATIONS SEE PRIMARILY WIND AS THE
TROUGH MOVES THROUGH SATURDAY NIGHT AND SUNDAY. AT THIS
TIME...THE MODEL PROGGS ARE IN PRETTY DECENT AGREEMENT THROUGH THE
WEEKEND. SO...CONFIDENCE IS ABOVE NORMAL IN THIS SOLUTION. STRONG
ZONAL FLOW SUNDAY NIGHT THROUGH MONDAY WILL KEEP THE LOWER
ELEVATIONS DRY AND BREEZY WHILE WEST FACING SLOPES OF THE
SOUTHWEST MOUNTAINS MAY SEE SOME BRIEF PRECIPITATION FROM ANY WEAK
SHORT WAVE IN THE WESTERLY FLOW.
AS WE HEAD TOWARD THE MIDDLE PART OF NEXT WEEK THE MODELS
INDICATE ANOTHER BROAD TROUGH DEVELOPING OVER THE WEST. HOW THIS
EVENTUALLY UNFOLDS HAS A GREAT DEAL OF UNCERTAINTY. THE ECMWF CUTS
OFF THE UPPER LOW AND MOVES IT THROUGH THE GREAT BASIN AND
CLOBBERS OUR FORECAST AREA...MAINLY IN THE MOUNTAINS...WITH WHAT
COULD BE A WINTER STORM. THE GFS ON THE OTHER HAND DIVES THE UPPER
LOW FURTHER SOUTH AND SLOWS IT DOWN KEEPING OUR REGION GENERALLY
DRY. BLENDED THE TWO FOR NOW LEANING A BIT TOWARD A DRIER SCENARIO
AS PREVIOUS TROUGHS UP TO THAT POINT LOOK TO BE SPLIT FLOWS...AND
THAT CAN OFTEN TIMES BECOME A PERSISTENT OCCURRENCE. THAT
SAID...MIDDLE OF NEXT WEEK MAY BE INTERESTING. BT
&&
.AVIATION...
UNSETTLED WEATHER CONDITIONS WILL CONTINUE OVER THE FORECAST AREA
TODAY. AREAS OF LIGHT TO MODERATE SHOWERS WITH EMBEDDED
THUNDESTORMS ARE EXPECTED IN THE EAST...AS WELL AS OVER THE HIGHER
TERRAIN AND NEARBY AREAS IN THE WEST. WESTERLY WINDS ARE EXPECTED
TO INCREASE WITH SUSTAINED SPEEDS 15 TO 25 KTS AFFECTING WESTERN
ROUTES BY 18Z AND SPREADING EAST THROUGH THE AFTERNOON. BT
&&
.PRELIMINARY POINT TEMP/POPS...
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 072 045/065 046/076 047/082 053/068 048/071 051/071
5/T 20/B 00/U 00/U 12/T 10/B 01/B
LVM 058 038/066 038/077 041/081 046/065 042/068 046/068
7/T 20/B 00/U 00/U 22/T 11/B 12/W
HDN 075 046/067 041/078 047/085 051/072 046/073 050/074
5/T 21/B 00/U 00/U 12/T 10/B 01/B
MLS 076 048/065 044/075 048/084 054/073 050/075 053/074
5/T 32/W 00/U 00/U 12/T 10/U 01/B
4BQ 077 047/064 041/075 045/082 053/075 047/074 050/075
5/T 31/B 00/U 00/U 12/T 20/U 01/U
BHK 080 048/063 038/071 044/079 050/075 047/073 049/074
4/T 32/W 00/U 00/U 02/T 20/U 01/U
SHR 074 043/063 038/076 044/083 050/070 044/071 048/072
4/T 21/B 00/U 00/U 12/T 20/U 01/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
256 PM MDT WED SEP 18 2013
.DISCUSSION...
ANOTHER ACTIVE WX SCENARIO SHAPING UP OVER THE REGION FOR REMAINDER
OF TODAY THRU THURSDAY. CIRA LAYERED TOTAL PW PRODUCT SHOWS ABUNDANT
LOW/MID LEVEL MOISTURE ACROSS THE REGION WITH VERY DRY CONDITIONS
ALOFT. VALUES ARE ON THE ORDER OF 130-160 PCT OF NORMAL. A THIN 30-
50 KT UPPER JET AXIS OVER NM AS SEEN ON THE LATEST AMDAR DATA IS
INTERACTING WITH THE LOW LEVEL MOISTURE AND INSTABILITY TO PRODUCE
A WELL DEFINED BAND OF THUNDERSTORMS OVER WESTERN AND NORTHERN NM.
STEERING FLOWS ARE STRONG TODAY HOWEVER THE SHEAR AXIS IS ORIENTED
IN THE DRXN OF STORM MOTION SO MORE LOCALLY HEAVY RAINFALL ON TAP.
LATEST HRRR SHOWS THIS AREA OF SHOWERS AND STORMS PROPAGATING EVER
SO SLOWLY EAST THIS EVENING INTO THE RIO GRANDE VALLEY AND NEARBY
HIGH TERRAIN. HAVE RAISED POPS TO HIGH CHANCE AND LIKELY FOR CENTRAL
NM.
EVEN MORE ACTIVE CONDITIONS WILL TAKE SHAPE INTO THURSDAY NIGHT BUT
MORE INTO THE EASTERN PLAINS. A LARGE UPPER TROUGH OVER THE PACIFIC
NW WILL SLIDE EAST INTO THE GREAT PLAINS AND HELP DRIVE A SURFACE
BACK DOOR FRONTAL BOUNDARY INTO NM. MEANWHILE...A VERY WELL DEFINED
UPPER WAVE EMBEDDED ON THE BACK SIDE OF THE LARGE SCALE WAVE WILL
SLIDE OVER NORTHERN NM AND HELP LIFT FOCUS OVER FRONT. CURRENT QPF
VALUES ARE POTENTIALLY TOO LOW FOR THIS EVENT ACROSS THE EAST WHERE
SUBSTANTIALLY MOISTURE REMAINS IN PLACE. FLOODING IS NOT EXPECTED
HOWEVER SOME LOCALIZED IMPACTS ARE LIKELY IF THE RAIN FALLS OVER
THE WRONG SPOT. ALSO RAISED POPS FOR THE EASTERN PLAINS THURSDAY
NIGHT TO LIKELY. TEMPS THROUGH THIS PERIOD WILL COOL BELOW NORMAL
FOR MUCH OF THE REGION...ESPECIALLY THE EAST.
MODELS DO INDICATE STRONGER WESTERLIES AND DRIER AIR SHIFTING EAST
INTO THE STATE FRIDAY THRU SUNDAY HOWEVER STRONG MOISTURE RECYCLING
PROCESSES WILL STILL BE AT PLAY. LOW CLOUDS AND FOG ARE POSSIBLE
ANY NIGHT ESPECIALLY IF SKIES CLEAR AND WINDS TAPER OFF. TEMPS WILL
BE COOL OUT WEST WHERE MUCH DRIER DEWPOINTS WILL MOVE IN. THE
EXTENDED PATTERN IS STILL HIGHLY UNCERTAIN SO MADE NO CHANGES. THE
ECMWF PROGS A DEEP LARGE SCALE STATIONARY UPPER LOW OVER THE GREAT
BASIN WITH A RELATIVELY ABUNDANT MONSOONAL MOISTURE TAP OVER NM. THE
GFS HAS AN EVEN DEEPER TIGHTLY WOUND COLD UPPER LOW DRIVING EAST
ACROSS THE CENTRAL ROCKIES THRU MID WEEK.
GUYER
&&
.FIRE WEATHER...
SCATTERED WETTING THUNDERSTORMS FOUND ACROSS WESTERN AND NORTHERN
AREAS WILL TRANSITION EASTWARD THIS EVENING BEFORE DIMINISHING SOME.
DRIER AIR WILL EVENTUALLY FILL IN FROM WEST TO EAST LATER TONIGHT
AND WILL SET THE STAGE FOR A DRIER WESTERN AND CENTRAL AREAS ON
THURSDAY.
A BACK DOOR COLD FRONT IS STILL EXPECTED FOR THURSDAY WITH EASTERN
AREAS OBSERVING THAT INFLUENCE. THIS INCLUDES WETTING SHOWERS AND
THUNDERSTORMS WHICH WOULD FAVOR MOST OF THE EASTERN PLAINS THURSDAY
AFTERNOON INTO THE OVERNIGHT. MIXING HEIGHTS WILL INCREASE ACROSS
THE MAJORITY OF THE AREA ALTHOUGH TRANSPORT WINDS WILL COME DOWN
MOST AREAS SO VENTILATION RATES WILL LOWER PRETTY MUCH AREAWIDE.
THE BACK DOOR COLD FRONT WILL PUSH THROUGH THE CENTRAL MOUNTAINS
THURSDAY NIGHT AND MOST LIKELY MAKE IT TO THE AZ STATE LINE BY
FRIDAY MORNING. MIXING DURING FRIDAY AFTERNOON SHOULD SET UP A
CONVERGENCE BOUNDARY NEAR THE CONTINENTAL DIVIDE AND MOST LIKELY
PROVIDE A FOCUS FOR THUNDERSTORMS THERE. THE ATMOSPHERE COULD BE TOO
STABLE FOR SIGNIFICANT SHOWER AND THUNDERSTORM DEVELOPMENT ACROSS
CENTRAL AND EASTERN AREAS DUE TO RESIDUAL IMPACTS FROM THE COLD
FRONT. HUMIDITY VALUES WILL BE UNSEASONABLY HIGH FRIDAY AFTERNOON.
TEMPERATURES WILL BE COOLER THAN NORMAL CENTRAL AND EASTERN AREAS
WHILE BEING NEAR NORMAL WEST OF THE CONTINENTAL DIVIDE. VENTILATION
RATES WILL BE LOWEST EXTENDING FROM ZONE 109 NORTHEASTWARD OVER THE
MIDDLE RIO GRANDE VALLEY AND AREAS TO THE LEE OF THE SANGRE DE
CRISTOS.
THE NEXT PACIFIC TROUGH WILL PLUNGE INTO THE FAR WESTERN US SATURDAY
AND CONTINUE TO TRAVERSE ACROSS THE INTERMOUNTAIN WEST ON SUNDAY.
MOISTURE WILL TRY TO SEEP UP FROM MEXICO AHEAD OF THIS TROUGH SO
LOOK FOR UNSETTLED WEATHER ACROSS THE WEST ON SATURDAY TRANSITIONING
SOME EASTWARD ON SUNDAY. WETTING RAIN WOULD CERTAINLY BE POSSIBLE
ALTHOUGH NOT AS WIDESPREAD AS THE PREVIOUS WEEK. HUMIDITY IS
EXPECTED TO TREND UP ACROSS THE WEST ON SATURDAY WHILE LOWER ACROSS
THE EAST. ON SUNDAY...HUMIDITY IS EXPECTED TO LOWER AREAWIDE
ALTHOUGH THIS COULD CHANGE. VENTILATION WILL INCREASE DURING THE
WEEKEND THANKS TO STRONGER WEST/SOUTHWEST TRANSPORT WIND. CONFIDENCE
IS PRETTY GOOD THAT A PACIFIC TROUGH WILL IMPACT THE AREA BUT STILL
NOT TOTALLY SURE ABOUT HOW MUCH MOISTURE WILL SEEP UP FROM THE SOUTH
AND FEED THE TROUGH. SURFACE WIND SHOULD ALSO INCREASE DURING THE
WEEKEND PERIOD.
ANOTHER PACIFIC TROUGH IS EXPECTED TO AFFECT THE WESTERN US BY THE
MIDDLE OF NEXT WEEK. THE LONG RANGE MODELS DIFFER SOMEWHAT IN THE
EXTENSION SOUTHWARD OF THE TROUGH BUT EITHER WAY IMPACT POTENTIAL
WOULD INCREASE BY MID NEXT WEEK. DEPENDING ON HOW THE TROUGH COMES
IN...ADDITIONAL WETTING RAIN WOULD BE POSSIBLE. CONDITIONS FOLLOWING
THE TROUGH PASSAGE COULD LEAD TO THE MOUNTAINS FIRST BIG FREEZE OF
THE FALL SEASON SO WILL BE WATCHING THAT AS THAT WOULD BEGIN THE
CURING PROCESS TO THE ABUNDANT FUELS THAT HAVE GREENED UP THIS SUMMER.
50
&&
.AVIATION...
18Z TAF CYCLE
SATELLITE...RADAR IMAGERY AND LIGHTNING TRENDS POINT TOWARDS A
POTENT UPPER LEVEL WAVE AND MID LEVEL FRONTAL BAND PASSAGE TODAY.
THE MOST ACTIVE AREA WILL BE FOUND ACROSS THE NORTHWEST HALF
THROUGH THIS AFTERNOON AND THEN TRANSITION EASTWARD DURING THE
EVENING. WENT BULLISH FOR VCSH AND VCTS AND ASSOCIATED CB/S AT
MANY TERMINAL SITES. WENT WITH A TEMPO AT SAF WITH SOME MODERATE
VIS RESTRICTIONS AND GUSTIER WINDS. BUT CANT RULE OUT THAT AT ABQ
AND EVENTUALLY LVS AS THE DAY PROCEEDS. WILL DEFINITELY UPDATE
ONCE A CLEARER PICTURE OF THE STORM EFFECTS COMES INTO VIEW. GUSTY
OUTFLOW WINDS AND PAST MOVING STORMS WITH BRIEF MVFR CONDITIONS
WILL BE THE THREAT OF THE DAY. CANT RULE OUT CONVECTIVE GUSTS TO 50
KT IN THIS ENVIRONMENT ALTHOUGH WENT LIGHTER IN THE TERMINAL
FORECASTS. FOLLOWING THE DISTURBANCE PASSAGE...A BRIEF BREAK COULD
CREATE ADDITIONAL LOW CIGS/VIS RESTRICTIONS ACROSS EASTERN AND
CENTRAL AREAS. THE HIGH MOUNTAIN BASINS ARE SUSCEPTIBLE BUT ALSO
THINKING PORTIONS OF THE EASTERN PLAINS LIKE WHAT WAS OBSERVED
EARLIER THIS MORNING. WILL BE WATCHING ROW CLOSELY TONIGHT.
50
&&
.PRELIMINARY POINT TEMPS/POPS...
FARMINGTON...................... 55 80 50 80 / 20 5 5 5
DULCE........................... 48 76 42 76 / 30 5 10 5
CUBA............................ 51 79 46 76 / 50 10 10 5
GALLUP.......................... 50 78 44 78 / 20 5 5 5
EL MORRO........................ 48 74 45 73 / 40 10 10 5
GRANTS.......................... 49 76 45 74 / 40 5 10 5
QUEMADO......................... 51 78 48 77 / 40 10 10 5
GLENWOOD........................ 54 81 54 82 / 30 10 5 10
CHAMA........................... 47 68 41 68 / 40 10 10 10
LOS ALAMOS...................... 55 75 51 70 / 60 10 10 5
PECOS........................... 53 71 49 64 / 50 20 30 10
CERRO/QUESTA.................... 51 73 45 70 / 50 20 20 5
RED RIVER....................... 44 64 40 61 / 60 30 30 10
ANGEL FIRE...................... 40 68 36 64 / 50 30 30 5
TAOS............................ 51 74 44 71 / 50 20 20 5
MORA............................ 50 72 45 64 / 40 30 30 10
ESPANOLA........................ 55 81 51 76 / 50 10 10 5
SANTA FE........................ 55 74 51 70 / 50 10 20 10
SANTA FE AIRPORT................ 55 78 53 72 / 50 10 10 5
ALBUQUERQUE FOOTHILLS........... 60 80 57 76 / 50 5 10 5
ALBUQUERQUE HEIGHTS............. 62 82 60 78 / 50 5 10 5
ALBUQUERQUE VALLEY.............. 61 83 59 79 / 50 5 10 5
ALBUQUERQUE WEST MESA........... 60 84 58 80 / 50 5 10 5
LOS LUNAS....................... 60 83 58 79 / 50 5 10 5
RIO RANCHO...................... 60 84 58 79 / 50 5 10 5
SOCORRO......................... 62 84 61 81 / 50 10 10 5
SANDIA PARK/CEDAR CREST......... 56 79 52 73 / 60 20 20 10
TIJERAS......................... 56 77 53 72 / 60 10 20 5
MORIARTY/ESTANCIA............... 51 75 50 69 / 50 20 30 10
CLINES CORNERS.................. 54 74 51 66 / 40 30 50 10
GRAN QUIVIRA.................... 55 75 52 70 / 40 20 30 10
CARRIZOZO....................... 57 77 56 73 / 20 10 20 10
RUIDOSO......................... 52 69 53 65 / 30 30 30 30
CAPULIN......................... 56 72 48 66 / 20 40 40 5
RATON........................... 54 76 49 69 / 20 30 40 5
SPRINGER........................ 55 78 50 70 / 20 30 40 5
LAS VEGAS....................... 53 74 48 65 / 30 30 40 5
CLAYTON......................... 62 76 54 71 / 20 40 50 5
ROY............................. 58 77 53 68 / 20 40 50 5
CONCHAS......................... 64 82 60 73 / 10 30 50 5
SANTA ROSA...................... 62 82 59 72 / 20 30 60 10
TUCUMCARI....................... 66 84 61 76 / 10 30 60 5
CLOVIS.......................... 63 80 61 74 / 5 30 60 10
PORTALES........................ 62 80 61 74 / 5 30 60 20
FORT SUMNER..................... 64 82 62 76 / 10 20 60 10
ROSWELL......................... 65 83 64 79 / 10 30 40 20
PICACHO......................... 58 78 57 72 / 20 20 30 20
ELK............................. 55 73 54 68 / 40 30 30 40
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1240 PM CDT WED SEP 18 2013
.UPDATE...
ISSUED AT 1224 PM CDT WED SEP 18 2013
FORECAST CHALLENGES THIS UPDATE PERIOD IS MAINLY MAXIMUM
TEMPERATURES AND PCPN CHANCES.
CLEARING JUST STARTING TO WORK INTO FAR SW FA ALONG ND/SD BORDER
AREA AND ALSO SEEING SOME BREAKS TAKING PLACE IN THE CENTRAL
VALLEY. WILL LIKELY CONTINUE TO SEE CLEARING SPREADING NORTHWARD
HOWEVER HOW MUCH WE CAN RECOVER IN MID SEPTEMBER IN QUESTION.
THERMAL RIDGE AXIS OVER FA SO ANY SOLAR SHOULD RESULT IN QUICK
RECOVERY. AM HESITANT TO DROP TEMPERATURES TOO MUCH IN CASE
CLEARING ACCELERATES/EXPANDS SO WILL ONLY MAKE SOME MINOR
ADJUSTMENTS. SMALL CLUSTER OF CONVECTION WHICH AFFECTED A SMALL
PART OF THE CENTRAL/NORTHERN FA CONTINUES TO WEAKEN SO WILL KEEP
FORECAST DRY MOST AREAS. WILL KEEP LOW POPS ACROSS W/NW FA LATE
AFTERNOON IN CASE AREA OF SHOWERS ACROSS N CENTRAL ND CLIP FAR NW
FA AND IF SOMETHING CAN GET GOING ALONG NW/SE ORIENTED BOUNDARY
FROM WEST CENTRAL ND TO SE ND/SD BORDER AREA.
UPDATE ISSUED AT 936 AM CDT WED SEP 18 2013
CHANGES THIS UPDATE PERIOD WERE TO EXTEND/EXPAND LOW POPS ACROSS
CENTRAL PORTIONS OF FA AS CONVECTION HOLDING TOGETHER AS IT
PROPAGATES ENE INTO CENTRAL/NORTHERN FA. ACTUALLY SEEING A FEW LTG
STRIKES SO MENTIONED THUNDER FOR THE REMAINDER OF THE AM. WITH LOW
CIGS FOG HOLDING ON A LITTLE LONGER BUT SHOULD CONTINUE TO
IMPROVE. WILL ADDRESS CLOUD TRENDS AND TEMPERATURES NEXT UPDATE.
UPDATE ISSUED AT 714 AM CDT WED SEP 18 2013
EXPANDED 20 POPS ACROSS THE FAR WESTERN FORECAST AREA FROM 12 TO
15 UTC THIS MORNING TO ACCOUNT FOR BAND OF LIGHT SHOWERS FROM
HARVEY TO EDGELEY...MOVING TO THE EAST-NORTHEAST AROUND 25 MPH.
HRRR SUGGESTS THIS ACTIVITY SHOULD DISSIPATE AS IT PROPAGATES
EAST. OTHERWISE...MADE SOME MINOR ADJUSTMENTS TO CLOUD COVER.
REST OF THE FORECAST IN GOOD SHAPE.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013
CHALLENGES INCLUDE CLOUD COVER AND TEMPERATURES THROUGH THE DAY
AND THEN CONVECTIVE CHANCES AND SEVERE POTENTIAL THIS EVENING
THROUGH THURSDAY. DESPITE DIFFERING QPF AMOUNTS AND LOCATIONS...
GFS/NAM/ECMWF ARE IN GOOD OVERALL AGREEMENT WITH SURFACE LOW TRACK.
THE GEM IS AN OUTLIER AND WILL NOT BE CONSIDERED WITH THIS FORECAST.
FOCUSED ON THE RAP FOR NEAR TERM CLOUD/TEMPERATURE TRENDS.
LOW CLOUDS HAVE ONCE AGAIN ENVELOPED THE ENTIRE FORECAST AREA AND
EXPECT A VERY SLOW EROSION FROM SOUTHWEST TO NORTHEAST THROUGH THE
DAY DUE TO MOIST SOUTH-SOUTHEAST FLOW AND A STRONG MID-LEVEL
INVERSION. RAP 925 HPA RH SUGGESTS THE SUN SHOULD BEGIN TO MAKE AN
APPEARANCE ACROSS SOUTHEAST ND INTO THE DEVILS LAKE BASIN BY EARLY
AFTERNOON...BUT MUCH OF NORTHEAST ND INTO NORTHWEST MN WILL REMAIN
CLOUDY THROUGH THE DAY. WITH INCREASED CLOUD COVER...DROPPED
HIGH TEMPERATURES 3 TO 5 DEGREES. THIS MAY STILL NOT BE ENOUGH
NOTING YESTERDAY/S SLOW RECOVERY. AS A RESULT...SOME AREAS ACROSS
THE NORTH MAY NOT TOP 70 DEGREES. OTHERWISE...HIGHS WILL RANGE
FROM THE LOW 70S ACROSS THE NORTH TO THE LOW 80S ACROSS THE SOUTH.
ADDED SOME SLIGHT CHANCE POPS TO THE DEVILS LAKE BASIN THIS MORNING
TO ACCOUNT FOR WEAKENING ECHOES CURRENTLY ACROSS THE WESTERN HALF
OF ND. OTHERWISE...MOST OF THE DAY SHOULD BE DRY GIVEN A STRONG
CAP AND DELAYED DYNAMIC SUPPORT. REMOVED POPS THROUGH 21 UTC...
INCREASING TO HIGH CHANCES FROM WEST TO EAST THEREAFTER.
SURFACE LOW WILL TRACK ALONG THE ND/SD BORDER WITH A WARM FRONT
EXTENDING TO THE EAST AND INTO WEST CENTRAL MN. CLEARING SKIES
LATE THIS AFTERNOON WILL HELP REALIZE 2000 TO 3000 J/KG OF
INSTABILITY AND WITH PWATS INCREASING TO 1.5 INCHES AND THE
APPROACHING WARM FRONT...EXPECT SCATTERED CONVECTIVE DEVELOPMENT
INITIALLY ACROSS THE SOUTHERN FORECAST AREA. SHOWERS AND
THUNDERSTORMS SHOULD EXPAND NORTHWARD THROUGH THE EVENING WITH THE
APPROACHING COLD FRONT AND STRONG FORCING ALOFT. SPC DAY ONE
CONVECTIVE OUTLOOK HAS EXPANDED ITS SLIGHT RISK TO INCLUDE ALMOST
ALL OF EASTERN ND AND PORTIONS OF NORTHWEST MN. SOME STORMS MAY
BECOME STRONG TO SEVERE WITH THE PRIMARY THREATS BEING LARGE HAIL
AND DAMAGING WIND...BUT CANNOT RULE OUT A TORNADO OR TWO...
ESPECIALLY NEAR FRONTAL BOUNDARIES.
THUNDERSTORMS THAT DEVELOP WILL MOVE EASTWARD AHEAD OF THE ADVANCING
COLD FRONT AND SHOULD EXIT THE FORECAST AREA BY NOON ON THURSDAY.
BREEZY NORTHWEST WIND WILL FOLLOW FRONTAL PASSAGE WITH COOLING
TEMPERATURES. HIGHS THURSDAY WILL RANGE FROM THE LOWER 60S ACROSS
THE NORTHWEST TO THE LOWER 70S ACROSS THE SOUTHEAST.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013
WITH THE EXCEPTION OF SOME LINGERING WRAP-AROUND SHOWERS ACROSS
THE LAKE OF THE WOODS REGION...FRIDAY WILL BE PARTLY SUNNY AND DRY
AS SURFACE HIGH PRESSURE BUILDS ACROSS THE NATION/S MID-SECTION.
BREEZY NORTHWEST WIND WILL PERSIST AND TEMPERATURES WILL TOP OUT
IN THE LOWER TO MID 60S REGION-WIDE.
SATURDAY-TUESDAY...00Z MODELS APPEAR STABLE RUN TO RUN AND CONFIDENCE
IS SLIGHTLY BETTER THAN AVERAGE. PERIOD BEGINS WITH RIDGING ALOFT...
WITH SOUTHWEST FLOW DEVELOPING BY THE END OF THE WEEKEND. THE
STRONGEST SIGNAL FOR PRECIP APPEARS TO BE MONDAY-MONDAY NIGHT.
SOUTHWEST FLOW ALOFT CONTINUES INTO TUESDAY...ALTHOUGH THERE IS NO
CLEAR SIGNAL FOR PRECIP. TEMPERATURES WILL BEGIN NEAR NORMAL...AND
TRANSITION TO SLIGHTLY ABOVE NORMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1234 PM CDT WED SEP 18 2013
IFR CLOUD DECK HANGING TOUGH OVER THE REGION THIS AFTERNOON...WILL
LIKELY TAKE A FEW MORE HOURS TO LIFT TO MVFR/VFR. NEXT UP WILL BE A
BATCH OF SHOWERS AND THUNDERSTORMS FOR THIS EVENING AND LATE NIGHT
THAT WILL MOVE EASTWARD OVERNIGHT AS A STRONG COLD FRONT SWEEPS
ACROSS THE DAKOTAS. TIMING AND COVERAGE UNCERTAINTY LINGERS...SO
THIS THREAT HAS BEEN COVERED WITH VCTS FOR THIS 18Z TAF ISSUANCE.
SOUTH-SOUTHEAST WIND AHEAD OF THE FRONT WILL DECREASE WITHIN THE
TROUGH AFTER 00Z...THEN SHIFT TO THE WEST-NORTHWEST AFTER FRONTAL
PASSAGE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...VOELKER
SHORT TERM...ROGERS
LONG TERM...ROGERS/TG
AVIATION...WJB
AREA FORECAST DISCUSSION
NWS TULSA OK
1211 PM CDT WED SEP 18 2013
.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
ONGOING LIGHT PRECIP MAY FOCUS INTO ISOLATED THUNDERSTORM
COVERAGE ACROSS SE OK/WC AND NW AR THIS AFTERNOON. ANTICIPATED
COVERAGE DOESNT APPEAR SIGNIFICANT ENOUGH TO IMPACT AVIATION
CONCERNS....SO WILL CONTINUE WITH VCTS ACROSS THOSE AREAS FOR THE
FIRST 6 HOURS OR SO. CONVECTIVE INFLUENCES ASIDE ...VFR CONDITIONS
WILL PREVAIL.
&&
.PREV DISCUSSION... /ISSUED 1030 AM CDT WED SEP 18 2013/
DISCUSSION...
FESTERING AREAS OF LIGHT RAIN/SPRINKLES ACROSS THE AREA THIS
MORNING. HOURLY HRRR OUTPUT MAINTAINS CONSISTENCY BY KEEPING THIS
ACTIVITY ONGOING WELL INTO THE AFTERNOON. WILL MAINTAIN THUNDER
CHANCES ACROSS THE EAST THIS AFTERNOON...AND ACROSS THE WEST WILL
CARRY SPRINKLES INTO MID AFTERNOON. PERSISTENT CLOUD COVER WILL
HAMPER AFTERNOON MAX TEMPS...SO HAVE LOWERED ADVERTISED HIGHS
EVERYWHERE. REST OF FORECAST BEYOND FIRST PERIOD LEFT AS IS.
UPDATED ZFP/PFM/AFM OUT SHORTLY.
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
SHORT TERM...99
LONG TERM....99
AVIATION...23
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
229 PM CDT WED SEP 18 2013
.SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)
ISSUED AT 229 PM CDT WED SEP 18 2013
MAIN CONCERN THROUGH THE SHORT TERM WILL BE SEVERE THUNDERSTORM
POTENTIAL THURSDAY AFTERNOON INTO THURSDAY EVENING.
WATER VAPOR IMAGERY COUPLED WITH RAP 500MB ANALYSIS SHOWS A WEAK
MID-LEVEL SHORTWAVE TROUGH ROTATING EASTWARD ACROSS CENTRAL WI WITH
INTERIM RIDGING EXTENDING FROM MO/IA INTO MN. VISIBLE
SATELLITE/SURFACE OBSERVATIONS SHOWING A FAIRLY LARGE AREA OF
LINGERING STRATUS ACROSS MN/WI BEHIND THIS DEPARTING WAVE AND IN
ADVANCE OF A SURFACE WARM FRONT EXTENDING FROM SD THROUGH NORTHERN
IA. OTHERWISE...WATER VAPOR DEPICTING A POTENT MID-LEVEL TROUGH WAS ROTATING
EASTWARD THROUGH MT AND THE INTERMOUNTAIN WEST. THIS WILL BE OUR MAIN
WEATHER-MAKER THROUGH THE NEXT 24-36 HOURS...INCLUDING THE POTENTIAL
FOR THURSDAY AFTERNOON/EVENING.
FOR TONIGHT...WILL BE WATCHING A WEAK MID-LEVEL SHORTWAVE TROUGH
MOVE TOWARD THE AREA FROM THE CENTRAL HIGH PLAINS. INCREASING
MOISTURE TRANSPORT INDICATED BY NAM IN THE 925-700MB LAYER NOSES
INTO THE AREA TOWARD MIDNIGHT IN ADVANCE OF THIS WAVE. BUFKIT
SOUNDINGS SHOWING ELEVATED INSTABILITY AT OR ABOVE 8KFT WITH NAM
ALSO INDICATING 1200-1500J/KG IN THE 2-5KM LAYER. NAM QPF FIELD
HOWEVER REMAINS DRY WHILE THE GFS/GEM INDICATE SOME LIGHTER
PRECIPITATION. BASED ON THE FORCING/INSTABILITY SIGNAL...FEEL THERE
IS LEAST A JUSTIFIABLE SLIGHT-LOW END SHOWER/THUNDERSTORM CHANCE.
FOR THURSDAY...POTENT MID-LEVEL TROUGH MOVING ACROSS THE NORTHERN
PLAINS WILL PUSH A SURFACE COLD FRONT INTO THE REGION THURSDAY
AFTERNOON DURING PEAK HEATING. TEMPERATURES TOPPING OFF IN THE UPPER
70S/LOWER 80S AND DEW POINTS IN THE UPPER 60S/AROUND 70 WILL COMBINE
WITH COOLING ALOFT ASSOCIATED WITH THE MID-LEVEL TROUGH TO PRODUCE
0-1KM MLCAPE IN THE 2000-3000J/KG RANGE. THEREFORE...THERE WILL BE
THE POTENTIAL FOR SEVERE THUNDERSTORMS IN THE AFTERNOON/EARLY EVENING HOURS.
ONE MITIGATING FACTOR WILL BE LACK OF GOOD CONVERGENCE RIGHT ALONG
THE FRONT...BUT FEEL MID-LEVEL FORCING WILL MAKE UP FOR THIS.
PRIMARY THREAT WILL BE LARGE HAIL ALONG WITH DAMAGING WINDS AS 0-3KM
BULK SHEAR INCREASES INTO THE 20-30KT RANGE FOR BETTER STORM
ORGANIZATION. LOOK FOR LINGERING SHOWERS AND THUNDERSTORMS THROUGH
THE EVENING WITH THE BULK OF THIS ACTIVITY SLIDING EAST OF THE AREA
WITH THE FRONT AFTER MIDNIGHT. PLAN ON OVERNIGHT LOWS TO DROP INTO
THE 50S BEHIND THE FRONT.
.LONG TERM...(FRIDAY TROUGH WEDNESDAY)
ISSUED AT 229 PM CDT WED SEP 18 2013
COOLER AIR FILTERS INTO THE REGION FRIDAY ON BREEZY NORTHWEST WINDS.
WITH 850-925MB LAYER TEMPERATURES IN THE 5-11C RANGE FROM NORTH TO
SOUTH...LOOK FOR HIGHS IN THE MIDDLE 60S ACROSS NORTH CENTRAL
WI...TO THE UPPER 60S ELSEWHERE.
LOOKS LIKE COOLER AND QUIET WEATHER THROUGH THE WEEKEND AS HIGH
PRESSURE BECOMES THE DOMINANT WEATHER FEATURE. HIGHS ARE EXPECTED TO
BE IN THE 60S/LOWER 70S SATURDAY AND SUNDAY WITH OVERNIGHT LOWS IN
THE UPPER 30S TO MIDDLE 40S.
FOR MONDAY THROUGH WEDNESDAY...THERE IS A SMALL CHANCE OF SHOWERS
CENTERED AROUND MONDAY NIGHT AS THE SOUTHERN PERIPHERY OF A
MID-LEVEL TROUGH ROTATING THROUGH CANADA BRUSHES THE AREA.
OTHERWISE... GFS AND ECMWF IN GOOD AGREEMENT ON RIDGE BUILDING
THROUGH MIDWEEK FOR A GRADUAL WARMING TREND. RIGHT NOW MODEL
CONSENSUS IS YIELDING HIGHS MAINLY IN THE MIDDLE 70S ON
WEDNESDAY...BUT WOULD NOT BE SURPRISED IF THESE TEMPERATURES
EVENTUALLY GET SHIFTED UPWARD INTO AT LEAST THE UPPER 70S TO LOWER
80S GIVEN THE STRENGTH OF THE UPPER LEVEL RIDGE AND INCREASING
SOUTHERLY SURFACE FLOW.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED
AT 1145 AM CDT WED SEP 18 2013
LOW STRATUS DECK MAKING STEADY BUT SLOW PROGRESS NORTHEAST...PER
LATEST SATELLITE TRENDS. NAM12/HRRR MORE AGGRESSIVE IN CLEARING THE
CLOUDS COMPARED TO THE RAP13...BUT THE RAP HAS A BETTER HANDLE ON
WHAT IS OCCURING. SATELLITE TRENDS SUGGEST A 21-22Z CLEARING AT
KRST/KLSE...WHICH LINES UP FAVORABLY WITH THE RAP. WILL STAY WITH
THIS TIMING.
TRICKY FORECAST TONIGHT WITH NUMERICAL GUIDANCE POINTING TO LOW
VSBYS AND POSSIBLY LOW CIGS. SEEMS TIED TO AN INCREASE IN THE LOW
LEVEL MOISTURE RETURN...WITH SOUTHWARD BUILDING STRATUS FROM THE
BACK EDGE OF THE CLOUD LAYER UNDER A LOW LEVEL INVERSION.
PLAUSIBLE...BUT NOT OVERLY CONFIDENT IN THIS RESULT. GOING TO STAY
WITH A MID LEVEL CLOUD DECK FOR NOW...AND SOME MVFR VSBY REDUCTIONS.
THIS WILL HAVE TO BE MONITORED CLOSELY AS THERE IS THE POTENTIAL FOR
LIFR/IFR CIGS/VSBYS.
COLD FRONT WILL SWEEP IN FROM THE WEST THU AFTERNOON. A LINE OF
SHOWERS/STORMS LOOK LIKELY...WITH THE ATMOSPHERE SUPPORTING A STRONG
TO SEVERE THREAT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1145 AM CDT WED SEP 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 248 AM CDT WED SEP 18 2013
MAIN FORECAST CONCERNS IN THE SHORT TERM ARE ON SHOWER CHANCES THIS
MORNING AND TEMPERATURES THIS AFTERNOON.
LATEST WATER VAPOR IMAGERY SHOWED A TWO SHORTWAVES MOVING ACROSS THE
WESTERN GREAT LAKES INTO THE UPPER MISSISSIPPI RIVER VALLEY. THE
FIRST WAVE WAS PUSHING ACROSS EASTERN WISCONSIN/ILLINOIS...WHILE THE
SECOND AS MOVING ACROSS SOUTHERN MINNESOTA/NORTHERN IOWA. A BROAD
TROUGH WAS NOTED OVER THE PACIFIC NORTHWEST INTO THE ROCKIES WITH
SEVERAL EMBEDDED SHORTWAVES NOTED. SURFACE OBSERVATIONS SHOWED
SURFACE LOW PRESSURE DEVELOPING OVER THE WESTERN DAKOTAS...WITH A
WARM FRONT EXTENDING SOUTHEAST ACROSS EASTERN SOUTH DAKOTA THROUGH
WESTERN IOWA INTO CENTRAL MISSOURI.
SHOWERS AND ISOLATED THUNDERSTORMS...WILL PERSIST ACROSS THE AREA
THIS MORNING. THIS ACTIVITY SHOULD THEN GRADUALLY LIFT NORTH LATE
THIS MORNING INTO THIS AFTERNOON AS THE WARM FRONT LIFTS NORTH
ACROSS THE UPPER MISSISSIPPI RIVER VALLEY. THE STRATUS WILL ALSO
LIFT NORTH WITH THE WARM FRONT GIVING WAY TO PARTLY SUNNY SKIES BY
LATE AFTERNOON. THE STRATUS SHOULD START TO BREAK UP BY EARLY
AFTERNOON OVER SOUTHEAST MINNESOTA AND NORTHEAST IOWA. CLOUDS LOOK
TO HANG ON UNTIL LATE AFTERNOON OVER WESTERN INTO CENTRAL
WISCONSIN. THE CLOUD COVER WILL HAVE A BIG IMPACT ON HIGH
TEMPERATURES TODAY. AREAS THAT SEE CLEARING EARLIER THIS AFTERNOON
WEST OF THE MISSISSIPPI RIVER CAN EXPECT HIGHS IN THE LOWER TO MID
80S. LOCATIONS OVER WESTERN INTO CENTRAL WISCONSIN WILL LIKELY
STRUGGLE TO GET OUT OF THE 70S...WITH EVEN COOLER TEMPERATURES
POSSIBLE OVER NORTH CENTRAL WISCONSIN WHERE THEY COULD BE IN THE
CLOUD COVER THE ENTIRE DAY. DEWPOINTS CLIMB INTO THE MID 60S THIS
AFTERNOON IN THE WAKE OF THE WARM FRONT WITH MLCAPE VALUES
CLIMBING INTO THE 1100 TO 1500 J/KG RANGE RIGHT ALONG AND WEST OF
THE MISSISSIPPI BY LATE AFTERNOON. NOT EXPECTING MUCH IF ANY
SHOWER OR THUNDERSTORM ACTIVITY IN THE WAKE OF THE WARM FRONT AS
WEAK UPPER RIDGING ATTEMPTS TO BUILD INTO THE REGION. 850 MB
MOISTURE TRANSPORT REALLY RAMPS UP LATE TONIGHT INTO EARLY
THURSDAY MORNING AHEAD OF A COLD FRONT AND VIGOROUS UPPER LEVEL
TROUGH APPROACHING FROM THE PLAINS. NOT SEEING MUCH SUPPORT FOR
SHOWERS OR STORMS WITH HEIGHT RISES NOTED OVER THE REGION AT 500
MB EARLY IN THE NIGHT. FLOW ALOFT TURNS SOUTHWEST LATE TONIGHT
INTO EARLY THURSDAY MORNING AS A TROUGH DIGS INTO THE WESTERN
DAKOTAS. WE START TO LOSE THE RIDGING ALOFT LATE TONIGHT SO WOULD
EXPECT SOME SHOWER AND THUNDERSTORM DEVELOPMENT LATE.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 248 AM CDT WED SEP 18 2013
MAIN FORECAST CONCERNS IN THE LONG TERM ARE ON SHOWER AND
THUNDERSTORM CHANCES ON THURSDAY INTO THURSDAY NIGHT...WITH THE
POTENTIAL FOR A FEW STRONG TO POSSIBLY SEVERE STORMS.
A COLD FRONT WILL PUSH INTO WESTERN MINNESOTA EARLY THURSDAY MORNING
AND WILL CONTINUE DRIVING EASTWARD ACROSS THE UPPER MISSISSIPPI
RIVER VALLEY THROUGH THE DAY ON THURSDAY INTO THURSDAY EVENING.
MEANWHILE...AN UPPER TROUGH WILL MOVE EAST OUT OF THE
CENTRAL/NORTHERN PLAINS. A MOIST AND UNSTABLE AIRMASS WILL BE IN
PLACE ACROSS THE FORECAST AREA AS THE FRONT MOVES IN. SHOWERS AND
STORMS ARE EXPECTED AHEAD OF AND ALONG THE FRONT ON THURSDAY. IF THE
STORMS HOLD OFF UNTIL THE AFTERNOON HOURS AND CAN DEVELOP RIGHT
ALONG THE FRONT...THERE WOULD BE THE POTENTIAL FOR A FEW STRONG TO
PERHAPS SEVERE THUNDERSTORMS. DEEP LAYER SHEAR IS LAGGING WELL
BEHIND THE FRONT...WITH THE UPPER JET POSITIONED WELL OFF TO THE
WEST. 0-6 KM BULK SHEAR VALUES ARE RATHER WEAK...IN THE 20 TO 25 KT
RANGE. HOWEVER...THE SHEAR DOES INCREASE BY LATE AFTERNOON AS THE
UPPER TROUGH ATTEMPTS TO CATCH UP TO THE FRONT. 0-6 KM BULK SHEAR
VALUES INCREASE SLIGHTLY TO AROUND 30 KTS BY LATE AFTERNOON...AND
MOST OF THIS SHEAR IS FOCUSED IN THE 0-3 KM LAYER. THINKING THE MAIN
HAZARDS FROM ANY STRONGER STORMS WOULD BE GUSTY WINDS AND POSSIBLY
SOME LARGE HAIL. THIS SHEAR INCREASE LOOKS TO OCCUR OVER WESTERN
INTO CENTRAL WISCONSIN SO THINKING THESE AREAS WOULD HAVE SLIGHTLY
HIGHER POTENTIAL AT SEEING SOME STRONGER STORMS. THE OVERALL SEVERE
THREAT LOOKS LOW AT THIS TIME...UNLESS STORMS HOLD OFF UNTIL LATER
IN THE AFTERNOON. THE FRONT SHIFTS EAST OF THE AREA FRIDAY MORNING
BUT THE UPPER TROUGH MOVES THROUGH DURING THE AFTERNOON HOURS.
LATEST GUIDANCE CONTINUES TO BE A LITTLE SLOWER WITH THE
PRECIPITATION EXITING THE AREA ON FRIDAY SO WE COULD SEE SOME
SHOWERS AND STORMS LINGER OVER CENTRAL AND SOUTHWEST WISCONSIN INTO
EXTREME NORTHEAST IOWA.
CLOUDS SHOULD GRADUALLY DECREASE FROM WEST TO EAST ACROSS THE AREA
FRIDAY AFTERNOON AS THE UPPER TROUGH SWINGS THROUGH AND HIGH
PRESSURE BUILDS IN FRIDAY AFTERNOON INTO FRIDAY NIGHT. HIGH PRESSURE
WILL THEN BE THE DOMINATE WEATHER FEATURE FROM FRIDAY NIGHT THROUGH
THE WEEKEND. A VERY PLEASANT WEEKEND ON TAP FOR THE REGION WITH
HIGHS IN THE 60S ON SATURDAY...THEN WARMING SLIGHTLY INTO THE UPPER
60S TO LOWER 70S ON SUNDAY. THERE IS THE POTENTIAL FOR SOME FROST
THIS WEEKEND OVER CENTRAL INTO NORTH CENTRAL WISCONSIN. LATE
SATURDAY NIGHT INTO EARLY SUNDAY MORNING LOOKS LIKE THE MOST
FAVORABLE TIMEFRAME FOR FROST WHEN TEMPERATURES DROP INTO THE MID
30S. RAIN CHANCES RETURN MONDAY INTO TUESDAY AS ANOTHER TROUGH MOVES
THROUGH THE REGION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1145 AM CDT WED SEP 18 2013
LOW STRATUS DECK MAKING STEADY BUT SLOW PROGRESS NORTHEAST...PER
LATEST SATELLITE TRENDS. NAM12/HRRR MORE AGGRESSIVE IN CLEARING THE
CLOUDS COMPARED TO THE RAP13...BUT THE RAP HAS A BETTER HANDLE ON
WHAT IS OCCURING. SATELLITE TRENDS SUGGEST A 21-22Z CLEARING AT
KRST/KLSE...WHICH LINES UP FAVORABLY WITH THE RAP. WILL STAY WITH
THIS TIMING.
TRICKY FORECAST TONIGHT WITH NUMERICAL GUIDANCE POINTING TO LOW
VSBYS AND POSSIBLY LOW CIGS. SEEMS TIED TO AN INCREASE IN THE LOW
LEVEL MOISTURE RETURN...WITH SOUTHWARD BUILDING STRATUS FROM THE
BACKEDGE OF THE CLOUD LAYER UNDER A LOW LEVEL INVERSION.
PLAUSIBLE...BUT NOT OVERLY CONFIDENT IN THIS RESULT. GOING TO STAY
WITH A MID LEVEL CLOUD DECK FOR NOW...AND SOME MVFR VSBY REDUCTIONS.
THIS WILL HAVE TO BE MONITORED CLOSELY AS THERE IS THE POTENTIAL FOR
LIFR/IFR CIGS/VSBYS.
COLD FRONT WILL SWEEP IN FROM THE WEST THU AFTERNOON. A LINE OF
SHOWERS/STORMS LOOK LIKELY...WITH THE ATMOSPHERE SUPPORTING A STRONG
TO SEVERE THREAT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...04
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1133 AM CDT WED SEP 18 2013
.UPDATE...
AREA OF THUNDERSTORMS IN EASTERN IOWA ASSOCIATED WITH 850MB WARM AIR
ADVECTION...LOW LEVEL JET FORCING AND A 500MB SHORTWAVE WILL TRACK
EAST ACROSS NORTHERN IL...WITH THE NORTHERN EDGE OF IT SLIDING
THROUGH SOUTHERN WI. THE HRRR AND OTHER MESOSCALE MODELS SHOW THIS
LITTLE COMPLEX WEAKENING THROUGH EARLY AFTERNOON. WITH HIGH
PRECIPITABLE WATER VALUES AND PERSISTENT WARM AIR ADVECTION OVER
SOUTHERN WI...ANY LITTLE SHORTWAVE COULD KICK UP SOME SCATTERED
SHOWERS ANYWHERE IN WI THIS AFTERNOON. THERE IS UPPER LEVEL
INSTABILITY WITH 800 J/KG OF CAPE TO SUPPORT ISOLATED THUNDER AS
WELL. THE NAM IS SHOWING WEAK SHORTWAVE ENERGY TRACKING THROUGH
CENTRAL/SOUTHERN WI DURING THE AFTERNOON TO WARRANT SLIGHT CHANCE
POPS.
CLOUDS WILL KEEP TEMPS DOWN TODAY...DESPITE 925MB TEMPS WARMING TO
22C WHICH WOULD SUGGEST HIGHS IN THE LOWER 80S. THE GOING FCST
ALREADY ACCOUNTS FOR THE CLOUDS WITH HIGHS IN THE MID/UPPER 70S OVER
MUCH OF THE AREA...SO NO CHANGES EXPECTED.
&&
.AVIATION/18Z TAFS/...
MVFR CIGS IN FAR WESTERN WI WITH DEEPER MOISTURE WILL GRADUALLY
SPREAD EAST INTO SOUTH CENTRAL WI EARLY THIS AFTERNOON. EXPECTING
DAYTIME LOW LEVEL MIXING TO PREVENT IT FROM GETTING AS FAR EAST INTO
MSN BUT THERE IS A SMALL CHANCE AND WILL CONTINUE TO MONITOR. NOT
EXPECTING IT TO MAKE IT TO THE EASTERN TAF SITES.
INCREASING THREAT FOR LIGHT FOG AS DEEPER RH SPREADS IN TNGT. WL
LEARN TOWARD CIGS REMAINING VFR FOR TNGT BUT ADD SOME LGT FOG.
PERIOD OF LOW LEVEL WIND SHEAR EXPCD TNGT AS LOW LEVEL JET
STRENGTHENS OVER THE REGION.
&&
.PREV DISCUSSION... /ISSUED 329 AM CDT WED SEP 18 2013/
TODAY AND TONIGHT...FORECAST CONFIDENCE...LOW TO MEDIUM
MULTIPLE FORCING MECHANISMS WILL CONTINUE TO TRIGGER SCATTERED
SHOWERS AND A FEW THUNDERSTORMS THIS MRNG. -SHRA FROM INITIAL SHORT
WAVE HAVE PUSHED EAST OF THE AREA. CURRENT -SHRA AND ISOLD T OVER
CWA BEING CAUSED BY FIRST SURGE OF THETA-E ADVECTION AS DEEPER
COLUMN MOISTURE AND WARM AIR SPREADS EASTWARD. FARTHER UPSTREAM...
STRONGER PUSH OF WARM AIR ADVECTION TRIGGERING SCT T OVER CENTRAL
IA. NOSE OF LOW LEVEL JET TRIGGERING THIS ACTIVITY SPREADS NORTHEAST
AND IS EXPECTED TO WEAKEN THIS MRNG. GREATER POTENTIAL FOR SCT SHRA
AND T TO AFFECT WESTERN CWA AFT 12Z. HOWEVER NEED TO KEEP CHANCE
CONTINUING IN EAST DUE TO WEAKER LIFT. DEEPER MOISTURE SPREADING
INTO SRN WI WL ALSO RESULT IN M/CLDY TO CLDY SKIES FOR A GOOD PART
OF THE DAY. CLDS MAY LINGER INTO TNGT BEFORE WARM FRONT PASSES BY
ALLOWING PARTIAL CLEARING AND PATCHY LIGHT FOG.
MAIN LIFT SPREADS EAST AND NORTH OF THE AREA LATER TODAY SO WL
CONTINUE WITH LOW/NO POPS LATER TODAY AND THIS EVENING. HOWEVER
WEAK LAYER Q-VECTOR CONVERGENCE LINGERS ACROSS SRN WI THRU TNGT.
WITH DEEP MOISTURE AND ELEVATED INSTABILITY IN PLACE AND INCREASING
LOW LEVEL JET AIMED AT SRN WI...NEED TO INCLUDE LOW POPS FOR T LATER
TNGT.
THURSDAY AND FRIDAY...FORECAST CONFIDENCE...MEDIUM
INSTABILITY IS EXPECTED TO INCREASE THURSDAY AS A WARM AND MOIST
AIRMASS IS PULLED INTO THE AREA AHEAD OF AN APPROACHING COLD FRONT.
NOT A REAL OBVIOUS TRIGGER FOR SHOWERS/STORMS DURING THE DAY...BUT
CONTINUED WEAK WARM ADVECTION ALONG WITH A VERY WEAK SHORTWAVE MAY
BE ENOUGH FOR AT LEAST SCATTERED CONVECTION. KEPT MAINLY CHANCE POPS
DURING THE DAY...INCREASING TO LIKELY FROM MADISON WESTWARD BY LATE
AFTERNOON AS THE FRONT DRAWS CLOSER. WENT LIKELY ACROSS THE FORECAST
AREA IN THE EVENING/OVERNIGHT AS THE FRONT MOVES INTO SOUTHERN
WISCONSIN. SOME STORMS COULD BE STRONG TO SEVERE LATE AFTERNOON INTO
THE EVENING GIVEN CAPE VALUES UP TO AROUND 2000 J/KG AND 0-6 KM BULK
SHEAR OF 20-30 KT. THE NEW SPC DAY 2 CONVECTIVE OUTLOOK HAS MOST OF
THE FORECAST AREA IN A SLIGHT RISK FOR SEVERE STORMS.
WITH SOME SUNSHINE EXPECTED THURSDAY...MAINTAINED HIGHS IN THE MID
80S. COULD BE A BIT LOWER IF MORE CLOUDS/PRECIP DURING THE DAY THAN
EXPECTED. ON THE FLIP SIDE...MODELS HAVE 925 MB TEMPS OF 23-25C...SO
UPPER 80S NOT OUT OF THE QUESTION IN SOME SPOTS GIVEN ENOUGH
SUNSHINE.
MODELS ARE STILL DIFFERING A BIT WITH THE TIMING OF THE COLD FRONT
AND MAIN SHORTWAVE FRIDAY. OVERALL THOUGH...SEEMS THAT MODELS ARE
TRENDING SLOWER...SIMILAR TO WHAT THE ECMWF HAS BEEN SUGGESTING FOR
THE LAST COUPLE RUNS. HAVE KEPT SOME HIGHER POPS THROUGH THE
MORNING...BUMPING UP AFTERNOON POPS A BIT. WILL LIKELY NEED TO
INCREASE POPS MORE IF THIS SLOWER TREND CONTINUES IN FUTURE MODEL
RUNS. COOLER TEMPS ARE LIKELY FRIDAY...THOUGH HIGHS ARE STILL
EXPECTED TO BE NEAR NORMAL VALUES.
SATURDAY THROUGH TUESDAY...FORECAST CONFIDENCE...MEDIUM
AFTER A FAIRLY ACTIVE PERIOD...HIGH PRESSURE IS EXPECTED TO SETTLE
IN FOR THE WEEKEND...HANGING ON INTO EARLY NEXT WEEK. SHOULD THUS
SEE A GOOD AMOUNT OF SUNSHINE SATURDAY THROUGH MONDAY WITH NEAR
NORMAL TEMPERATURES.
THE ECMWF IS MAINTAINING A STRONGER SHORTWAVE THAN THE GFS AND
CANADIAN MONDAY NIGHT INTO TUESDAY...THUS KEPT SOME LOW POPS
GOING.
AVIATION/12Z TAFS/...CIGS CONTINUE TO SLOWLY FALL AS DEEPER
MOISTURE SLOWLY SPREADS INTO SOUTHERN WI. EXPECT MVFR CIGS TO SPREAD
INTO KMSN EARLY THIS MRNG. CONFIDENCE LOWER ON MVFR CIGS REACHING
ERN TAF SITES BUT WL CARRY AT LEAST SOME TEMPO GROUPS LATER THIS
MRNG. DAYTIME MIXING MAY PREVENT A LONGER PERIOD OF LOWER CIGS IN
ERN SITES. INCREASING THREAT FOR LIGHT FOG AS DEEPER RH SPREADS IN
AS WELL TNGT. WL LEARN TOWARD CIGS REMAINING VFR FOR TNGT BUT ADD
SOME LGT FOG. PERIOD OF LOW LEVEL WIND SHEAR EXPCD TNGT AS LOW LEVEL
JET STRENGTHENS OVER THE REGION.
MARINE...TIGHTENING PRESSURE GRADIENT TODAY IN RESPONSE TO LOW
PRESSURE MOVING INTO THE NORTHERN PLAINS WILL CONTINUE TO BRING
GUSTY SOUTH TO SOUTHEAST WINDS...WITH A PROLONGED PERIOD OF 10 TO 20
KNOT WINDS. FEW WIND GUSTS LIKELY 22-25 KNOTS. BETTER CHANCE FOR
HIGHER WINDS AND RESULTANT WAVES NORTH OF PORT WASHINGTON DUE TO
SHORE ORIENTATION. EXPECTING WAVES TO BUILD TO OVER 4 FEET AT
TIMES. HENCE WL POST SMALL CRAFT ADVY FOR THIS AREA INTO THURSDAY
EVENING. AREAS FARTHER SOUTH WL NEED TO BE WATCHED CLOSELY BUT NOT
ENOUGH CONFIDENCE IN A PROLONGED PERIOD OF HIGHER WINDS AND WAVES AT
THIS TIME.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THURSDAY FOR LMZ643.
&&
$$
UPDATE...MRC
TODAY/TONIGHT AND AVIATION/MARINE...MBK
THURSDAY THROUGH TUESDAY...DDV