Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/03/12
AREA FORECAST DISCUSSION
NWS DENVER CO
837 PM MDT SUN SEP 2 2012
.UPDATE...MOST CONVECTION HAS SHIFTED EASTWARD ACROSS THE PLAINS
THIS EVENING...ALTHOUGH STILL ISOLATED SHOWERS/STORMS ON THE WEST
SLOPE. GOING FORECAST LOOKS GOOD...KEEPING LOW POPS AFTER MIDNIGHT
IN THE MOUNTAINS AND ACROSS PARTS OF THE PLAINS THAT LIE ON THE
SOUTHERN FRINGE OF THE UPPER LEVEL JET.
&&
.AVIATION...ONLY A VERY SLIGHT CHANCE OF SEEING ANOTHER
SHOWER/STORM AFFECT THE FRONT RANGE AIRPORTS THIS EVENING.
OTHERWISE LOOK FOR VFR CONDITIONS AND WINDS GRADUALLY
TRANSITIONING TO SOUTH/SOUTHWEST OVERNIGHT.
&&
.HYDROLOGY...NO THREATS FOR THE REST OF TONIGHT OR MONDAY WITH
FAST MOVING STORMS ONLY CAPABLE OF PRODUCING A QUARTER INCH IN
15 MINUTES.
&&
.PREV DISCUSSION... /ISSUED 259 PM MDT SUN SEP 2 2012/
SHORT TERM...DURING THE NEXT FEW HOURS SHOULD SEE A STEADY
INCREASE IN SHOWER/T-STORM FORMATION OVER THE MTNS AND HIGH
VALLEYS. THIS INCREASE IN CONVECTION IS IN RESPONSE TO A REGION
OF MID/UPPER LEVEL LIFT/INSTABILITY GENERATED ON THE NOSE OF
40-50KT 300-500MB JET MAXIMA DARTING NORTHEASTWARD ACROSS
SOUTHEAST UTAH AT THE MOMENT. AT ITS PRESENT SPEED SHOULD SEE THIS
WEATHER MAKER REACHING THE FRONT RANGE URBAN CORRIDOR/DENVER
METRO AREA AROUND 00Z THIS EVENING. MODELS INDICATE GENERALLY LIGHT
QPF ON THE NORTHEAST PLAINS DURING THE EVENING HOURS AS THIS JET
MAX AND WEAK QG ASCENT PASS OVERHEAD. WRF SYNTHETIC IR CLOUD MODEL
SHOWS A FAIRLY THICK SOUTHWEST-NORTHEAST SWATH OF CLOUD COVER ACROSS
THE FORECAST AREA PRETTY MUCH ALL EVENING....AND OVER THE FAR
NORTHEAST COUNTIES THROUGH THE EARLY MORNING HOURS. THIS MATCHES UP
WELL WITH 700-500MB RH FIELDS OF THE NAM...GFS...EC AND HI RES
MODELS. CURRENT FORECAST GRIDS INDICATE SCATTERED POPS IN THE HIGH
COUNTRY...WITH THE HIGHER PRECIP CHANCES ROUGHLY SOUTH OF I-70.
ON THE PLAINS 10-20 PERCENT POPS PREVAIL...ALTHOUGH THE HRRR AND
HI RES MODEL REFLECTIVITY FIELDS INDICATE A LINE OF STORMS FORMING
IN MORGAN...EASTERN ADAMS...EASTERN ARAPAHOE AND EASTERN ELBERT
COUNTIES BETWEEN 00-03Z...THEN MOVING EAST INTO WASHINGTON AND
LINCOLN COUNTIES AS THE EVENING GOES ON. STORMS APPEAR TO FORM
ALONG A WIND SHEER AXIS IN THE AREA. SHOULD THIS HAPPEN...NO DOUBT
PRECIP CHANCES WOULD NEED TO BE REVISED UPWARD IN THIS AREA.
BY LATE TONIGHT....THE WAVE MOVES EAST OF THE STATE AS THE
SOUTHWESTERLY FLOW ALOFT TRANSITIONS MORE TO A WESTERLY COMPONENT.
THE SHIFT IN WINDS ALOFT APPEAR TO MIX DOWN MONDAY MORNING CAUSING
DRYING ALONG THE EAST FACE OF THE FRONT RANGE...PARTICULARLY UP
NEAR THE WYOMING BORDER. DURING THE DAY...COULD SEE ISOLATED
STORMS FORMING ALONG THE PALMER RIDGE AND HIGHER AREAS ACROSS
SOUTHERN PORTIONS OF THE CWFA DURING THE AFTERNOON HOURS WITH
WEAK UPSLOPE FLOW WITH NORTHERLY BOUNDARY LAYER FLOW. OTHERWISE A
DRIER DAY WITH TEMPERATURE SIMILAR OR SLIGHTLY COOLER THAN TODAY.
LONG TERM...ON MONDAY NIGHT NIGHT...UPPER LEVEL HIGH PRESSURE IS
CENTERED OVER WEST TEXAS...WITH AN UPPER LEVEL TROUGH OF LOW
PRESSURE OVER THE NORTHERN ROCKIES. COLORADO LIES BETWEEN TWO
SYSTEMS UNDER THE INFLUENCE OF A WESTERLY FLOW ALOFT. BOTH THE NAM
AND THE GFS SHOW A 60 KT JET OVER NORTHEASTERN COLORADO...HOWEVER
ACCORDING TO THE MODELS...VERY LITTLE QG IS ASSOCIATED WITH THE
JET. AS FOR MOISTURE...MODELS SHOW THAT THE MOUNTAINS ARE VERY DRY
WITH PW`S LESS THAN ONE HALF INCH...WITH PW`S FROM THREE QUARTERS
OF AN INCH TO AN INCH EAST OF THE MOUNTAINS. NAM AND GFS SOUNDINGS
SHOW CAPE VALUES UNDER 300 J/KG...WITH DEWPOINTS IN THE 40S....AND
SOME MID LEVEL MOISTURE BETWEEN 500 AND 600 MILLIBARS. BOTH THE
NAM AND GFS ARE ALSO SHOWING LIGHT PRECIPITATION MOVING ACROSS
NORTHEASTERN COLORADO MAINLY SOUTH OF INTERSTATE 76 DURING THE
LATE EVENING AND OVERNIGHT. LOOKS LIKE THE BEST CHANCE FOR ANY
PRECIPITATION WOULD BE OVER THE PALMER DIVIDE...THEREFORE I HAVE
INCREASED POPS SLIGHTLY THERE. DUE TO THE INVERTED V SOUNDINGS...I
WOULD SUSPECT ANY STORMS WOULD BE PRODUCE MAINLY LIGHT RAIN AND
GUSTY WINDS.
ON TUESDAY INTO WEDNESDAY...DRIER AIR SPREADS ACROSS ALL OF
NORTHEASTERN COLORADO...ENDING ANY CHANCES OF PRECIPITATION ACROSS
THE CWA...WITH THE EXCEPTION OF PORTIONS OF THE CENTRAL MOUNTAINS
MAINLY SOUTH OF INTERSTATE 70.
WEDNESDAY NIGHT AND INTO THURSDAY...AN UPPER LEVEL TROUGH DROPPING
INTO THE NORTHERN ROCKIES WILL INDUCE A WEAK RIDGE OVER COLORADO.
THIS WILL PUSH TEMPERATURES ABOVE NORMAL AGAIN WITH A JUST A SLIGHT
CHANCE FOR SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON AND
EVENING HOURS.
AS THE UPPER LEVEL TROUGH MOVES EAST OVER THE NORTHERN PLAINS IT
WILL PUSH A COLD FRONT THROUGH COLORADO THURSDAY NIGHT. THIS WILL
USHER IN COOLER AIR FOR FRIDAY AND SATURDAY. NOT MUCH MOISTURE
BEHIND THE FRONT...SO WILL KEEP POPS LOW FOR NOW. IF ANY
PRECIPITATION DEVELOPS...IT IS EXPECTED TO BE LIGHT AND OCCUR
FRIDAY. SURFACE HIGH BEHIND THE FRONT WILL DRIFT SOUTH OVER COLORADO
FRIDAY. THE CLEAR SKIES COMBINED WITH THE COOL AND DRY AIRMASS WILL
LEAD TO COOL OVERNIGHT LOWS FRIDAY NIGHT.
ON SUNDAY...UPPER LEVEL RIDGE WILL BE OVER THE FOUR CORNERS. THIS
WILL SEND WARMER AIR BACK INTO COLORADO WITH HIGHS CLIMBING BACK
INTO THE 80S.
AVIATION...VFR CONDITIONS IN THE DENVER AREA THROUGH 00Z
TODAY. AFTER 00Z THIS EVENING...ISOLATED SHOWERS AND THUNDERSTORMS
MOVING OFF THE FRONT RANGE AND FORMING IN THE DENVER AREA COULD
LOWER CEILINGS TO AROUND 6000 FT AGL FOR SHORT PERIODS OF TIME.
THERE IS ALSO A SLIGHT CHANCE THAT MODERATE RAINFALL FROM PASSING
STORMS COULD BRIEFLY REDUCE VISIBILITIES TO 5 MILES. IMPROVEMENT
SHOULD OCCUR AFTER 04Z THIS EVENING WITH DRIER AIR MOVING DOWN
OFF THE FOOTHILLS. ON MONDAY...VFR CONDITIONS ARE ANTICIPATED
ALL DAY...HOWEVER THERE IS A SLIGHT CHANCE OF A LIGHT SHOWERS OR
WEAK T-STORM IN THE DENVER AREA AFTER 2 PM MDT.
HYDROLOGY...THERE IS A CHANCE THAT THE FRONT RANGE BURN SCARS
COULD SEE A FEW SHOWERS AND THUNDERSTORMS THIS EVENING WITH
PASSAGE OF A WEAK UPPER LEVEL WEATHER DISTURBANCE. THE STRONGER
STORMS MAY PRODUCE UP TO 0.30 INCH OF RAIN IN UNDER 35 MINUTES.
WHILE FLASH FLOODING IS NOT ANTICIPATED...THE BRIEF HEAVY RAINFALL
COULD CAUSE MINOR RISES IN CREEKS AND SMALL STREAMS AS WELL AS
SOME MUDDY RUNOFF. THIS SHOWERY PRECIPITATION SHOULD COME TO AN END
BY MIDNIGHT. ON MONDAY THERE ISA A SLIGHT CHANCE OF THUNDERSTORMS
AFTER 3 PM. ANY RAINFALL SHOULD BE LIGHT...GENERALLY UNDER A TENTH
OF AN INCH.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....MEIER
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1100 AM MDT SAT SEP 1 2012
.UPDATED...FIRST AND SECOND PERIODS
&&
.SHORT TERM...NECESSARY ADJUSTMENTS TO CURRRENT FCST...ALBEIT
MINOR...WILL INVOLVE FIRST AND SECOND PERIOD SKY COVER...PRECIP
PROBABILITIES...MAXIMUM TEMPERATURES AND WINDS MAINLY FOR THE
PLAINS. MAIN FOCUS TODAY WILL BE THE DEVELOPING CRITICAL WILDLAND
FIRE DANGER CONDITIONS ON THE PLAINS. A RED FLAG WARNING IS SLATED
TO START AT 1700Z/1100 MDT TODAY. HOWEVER LATEST 15 AND 30 MINUTE
SFC OBSERVATIONS WERE ALREADY INDICATING SOUTHERLY WIND GUSTS IN
THE 20-28KT RANGE AT A FEW LOCATIONS IN NORTHERN LINCOLN AND
WASHINGTON COUNTIES. WHILE RELATIVE HUMIDITY VALUES WERE STILL
GENERALLY ABOVE 20 PCT..BUT FALLING. THE 1700Z START TIME FOR THE
RED FLAG WARNING STILL LOOKS GOOD.
OTHER ATTENTION IS THE BAND OF CONVECTION DEVELOPING OVER WESTERN
COLORADO AT THE MOMENT. NOT SEEING ANY LIGHTNING STRIKES WITH IT
YET...BUT ONLY A MATTER OF TIME. DEVELOPMENT ATTRIBUTED IN PART TO
WEAK MID-LEVEL QUASI-GEOSTROPHIC ASCENT/LIFT AHEAD OF A WEAK
SHORTWAVE TROUGH MOVED ALONG BY PREVAILING SOUTHWEST FLOW ALOFT.
RUC INDICATES TO THE TROUGH AXIS JUST THE EAST OF THE
UTAH/COLORADO BORDER AT THIS HOUR. AT ITS CURRENT SPEED SHOULD
SEE THIS DISTURBANCE AND THE CONVECTION IT GENERATES MOVING OVER
OUR NORTH CENTRAL MTNS/NRN FRONT RANGE FOOTHILLS IN THE NEXT HOUR
OR SO. MOST IF NOT ALL OF THIS CONVECTION IS EXPECTED TO REMAIN
OVER THE HIGHER TERRAIN...HOWEVER HIGH BASED MOSTLY DRY STORMS
MOVING JUST OFF THE FOOTHILLS COULD GENERATE SOME PRETTY GUSTY
OUTFLOW WINDS BASED ON MODEL INVERTED-V SOUNDINGS ON THE PLAINS.
MAY SEE GUSTY OUTFLOW WINDS SPREADING OUT ACROSS PORTIONS OF THE
I-25 URBAN CORRIDOR AFTER 21Z TODAY WITH GUSTS POTENTIALLY TO
AROUND 30KT. COULD SEE THESE GUST BOUNDARIES CONTINUING TO MOVE
EAST CRISS-CROSSING THE PLAINS THROUGH THE EVENING...WHICH WOULD
PRETTY MUCH CUT DOWN THE GUSTY SOUTHERLY SFC WINDS OUT THERE THIS
AFTERNOON. AS FOR TEMPERATURES...I-25 URBAN CORRIDOR TEMPS MAY
STRUGGLE TO REACH THE MID 90S TODAY...BUT IN AREAS FARTHER EAST
COVERED BY THE RED FLAG WARNING READINGS ARE ALREADY IN THE
MID/UPPER 80S. SO NUDGED HIGH TEMPERATURES UP 1-3F OUT THERE.
.AVIATION...VFR CONDITIONS ARE ANTICIPATED AT DENVER AREA
AIRPORTS NOW THROUGH 12Z/SUNDAY. HOWEVER GUSTY OUTFLOW WINDS FROM
MOSTLY DRY HIGH BASED FORMING STORMS OVER THE FOOTHILLS AFTER 21Z
THIS AFTERNOON COULD PRODUCE GUSTS ON THE ORDER OF 25-35KT IN THE
DENVER AREA. THE CHANCE FOR THESE WIND SPEEDS OCCURRING AT APA
AND DIA IS NOT AS GREAT AS THAT FOR BJC CLOSER TO THE FOOTHILLS.
&&
.FIRE WEATHER...RED FLAG WARNING WILL GO INTO EFFECT AT 17Z/11 AM
MDT THIS MORNING AND WILL REMAIN IN EFFECT UNTIL 19Z/7 PM MDT
THIS EVENING FOR A LARGE PORTION OF NORTHEAST COLORADO. GUSTY
SOUTHERLY WINDS HAVE ALREADY DEVELOPED AT A NUMBER OF LOCATIONS
IN WASHINGTON AND NORTHERN LINCOLN COUNTIES AND BASED ON THE
LATEST MODEL DATA SHOULD BECOME MORE WIDESPREAD WITHIN THE NEXT
1-2 HOURS. AT THIS HOUR RELATIVE HUMIDITY VALUES STILL GENERALLY
ABOVE 20 PERCENT...BUT THEY SHOULD FALL WITHIN WARNING CRITERIA
IN THE NEXT HOUR OR TWO AT MOST LOCATIONS WITHIN THE WARNING
ACCORDING TO THE HRRR...RUC AND NAM.
&&
.HYDROLOGY...PROBABLY THE ONLY REAL CONCERN TODAY WILL BE BRIEF
LIGHT TO MODERATE RAINFALL PRODUCED BY WIDELY SCATTERED STORMS
MOVING OFF THE CONTINENTAL DIVIDE AFTER 1 PM MDT TODAY. ONE OR
TWO OF THESE STORMS MAY DRIFT OVER A FRONT RANGE BURN SCAR
POSSIBLY DEPOSITING UP TO A QUARTER INCH OF RAIN IN UNDER 25
MINUTES. HOWEVER ODDS OF THIS OCCURRING TODAY APPEAR LOW AS WE
MAY SEE MORE IN THE WAY OF GUSTY OUTFLOW WINDS AND CG LIGHTNING
WITH THESE HIGH BASED STORMS.
&&
.PREV DISCUSSION... /ISSUED 311 AM MDT SAT SEP 1 2012/
SHORT TERM...SAME OLD STORY AS THE UPPER LEVEL RIDGE CONTINUES
OVER THE AREA WITH SSW FLOW ALOFT. SUBTROPICAL MOISTURE WILL
CONTINUE TO AFFECT THE MTNS WITH SCT AFTN TSTMS WHILE THE HIGHER
VALLEYS AND FOOTHILLS SEE WDLY SCT STORMS. OVER NERN CO IT WILL
REMAIN HOT AND DRY ALTHOUGH OUTFLOW BOUNDARIES FROM HIGHER TERRAIN
CONVECTION MAY TRIGGER A FEW STORMS MAINLY WEST OF I-25. AFTN
HIGHS WILL BE IN THE 90S ACROSS NERN CO WITH HIGH FIRE DANGER.
GUSTY SOUTH WINDS WILL BE HIGH ENOUGH FOR RED FLAG CONDITIONS OVER
THE PLAINS. FOR TONIGHT SOME LINGERING SHOWERS/TSTMS WILL CONTINUE
OVER THE HIGHER TERRAIN THRU THE EARLY EVENING HOURS WITH MOST
ACTIVITY ENDING BY MIDNIGHT.
LONG TERM...FAIRLY STRONG WEST-SOUTHWESTERLY FLOW ALOFT IS PROGGED
OVER THE CWA SUNDAY THROUGH MONDAY NIGHT. THE SYNOPTIC SCALE ENERGY
IS WEAK SUNDAY THROUGH MONDAY NIGHT. THE LOW LEVEL PRESSURE AND
WIND FIELDS SHOW A WEAK COLD FRONT TO MOVE INTO THE PLAINS ON
SUNDAY. WEAK UPSLOPE IS PROGGED FOR THE PLAINS INTO SUNDAY
EVENING. ON MONDAY...THE GRADIENT IS WEAK SO NORMAL DIURNAL WIND
PATTERNS SHOULD PREVAIL. FOR MOISTURE...THEN IS SOME PROGGED
..MAINLY IN THE UPPER AND MID LEVELS ON SUNDAY INTO MONDAY
EVENING. DEW POINT PROGGS ARE MAINLY IN THE 40S F OVER THE PLAINS
..WITH 30S F IN THE MOUNTAINS ON SUNDAY...AND A TAD LOWER ON
MONDAY. THE GFS IS A BIT HIGHER THAN THE NAM. PRECIPITABLE WATER
VALUES ARE IN HE 0.90-1.00 INCH RANGE ON SUNDAY...THEN THE 0.75-0.85
INCH RANGE ON MONDAY. THERE IS A TAD OF CAPE PROGGED OVER THE
MOUNTAINS LATE DAY SUNDAY...NOTHING FOR THE PLAINS. BY LATE DAY
MONDAY...THE NAM ONLY HAS LIMITED CAPE OVER THE MOUNTAINS...WHILE
THE GFS HAS A TAD OVER THE FAR EAST. THE QPF FIELDS HAVE A TAD OF
MEASURABLE RAINFALL PROGGED OVER THE MOUNTAINS LATE DAY SUNDAY.
THERE IS EVEN LESS INDICATED FOR MONDAY. FOR POPS...WILL GO WITH
"CHANCE"S IN THE MOUNTAINS SUNDAY AFTERNOON AND EVENING...NOTHING
FOR THE PLAINS. FOR LATE DAY MONDAY...WILL GO WITH 20% IN THE
MOUNTAINS...10%S ELSEWHERE. CONCERNING FIRE WEATHER...WILL GO WITH
NO HIGHLIGHTS SUNDAY FOR THE PLAINS BECAUSE THE WINDS DON`T SEEM TO
BE AN ISSUE...AND RELATIVE HUMIDITIES WILL BE MARGINAL. IT WILL BE A
BIT COOLER SUNDAY EVEN THOUGH MOISTURE IS NOT GREAT. FOR
TEMPERATURES...SUNDAY`S HIGHS SHOULD BE 1.0-2.5 C COOLER THAN
SATURDAY`S HIGHS. MONDAY`S HIGHS MAY BE A TAD WARMER THAN
SUNDAY`S. FOR THE LATER DAYS...TUESDAY THROUGH FRIDAY...MODELS HAVE
A PRETTY FLAT UPPER RIDGE CENTERED TO THE SOUTH OF COLORADO WITH
MAINLY ZONAL FLOW ALOFT TUESDAY INTO THURSDAY NIGHT. ON FRIDAY...
BOTH THE GFS AND ECMWF SHOW A VIGOROUS UPPER TROUGH MOVING
SOUTHEASTWARD TO OUR NORTH AND NORTHEAST. THE FLOW ALOFT BECOMES
NORTHWESTERLY ON FRIDAY...AND BOTH MODELS SHOW A SIGNIFICANT COLD
FRONT TO MOVE IN THE CWA. THE GFS AND ECMWF ALSO SHOW A WEAKER COLD
FRONT TO MOVE IN ON WEDNESDAY. MOISTURE IS SPARSE FOR ALL THE
DAYS.
AVIATION...WINDS HAVE REMAINED SOUTH EARLY THIS MORNING AND
SHOULD BE SSW THRU LATE MORNING. BY 18Z LATEST HRRR SHOWS A WK
DENVER CYCLONE NR THE AIRPORT WITH LIGHT NLY WINDS DEVELOPING THRU
21Z. AFTER 21Z THE HRRR SHOWS AN OUTFLOW BNDRY MOVING ACROSS THE
AIRPORT FM CONVECTION OVER THE FOOTHILLS WITH WINDS BECOMING WNW.
COULD BRIEFLY SEE SOME WIND GUSTS TO 25 MPH OR SO WITH THIS BNDRY.
FOR NOW WILL NOT MENTION ANY TSTM ACTIVITY AT DIA. BY EARLY EVENING
WILL SHIFT WINDS BACK TO THE SW AND KEEP THEM THAT WAY OVERNIGHT.
A WK CDFNT WILL MOVE INTO THE AREA AFTER 12Z SUN WITH WINDS
BECOMING NLY BY 15Z.
HYDROLOGY...WIDELY SCATTERED THUNDERSTORMS WILL BE POSSIBLE IN
THE BURN AREAS THIS AFTERNOON WITH RAINFALL AMOUNTS AROUND A
QUARTER INCH OR LESS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BAKER/RPK
LONG TERM....RJK
AVIATION...BAKER/RPK
AREA FORECAST DISCUSSION
NWS DENVER CO
311 AM MDT SAT SEP 1 2012
.SHORT TERM...SAME OLD STORY AS THE UPPER LEVEL RIDGE CONTINUES
OVER THE AREA WITH SSW FLOW ALOFT. SUBTROPICAL MOISTURE WILL
CONTINUE TO AFFECT THE MTNS WITH SCT AFTN TSTMS WHILE THE HIGHER
VALLEYS AND FOOTHILLS SEE WDLY SCT STORMS. OVER NERN CO IT WILL
REMAIN HOT AND DRY ALTHOUGH OUTFLOW BOUNDARIES FROM HIGHER TERRAIN
CONVECTION MAY TRIGGER A FEW STORMS MAINLY WEST OF I-25. AFTN
HIGHS WILL BE IN THE 90S ACROSS NERN CO WITH HIGH FIRE DANGER.
GUSTY SOUTH WINDS WILL BE HIGH ENOUGH FOR RED FLAG CONDITIONS OVER
THE PLAINS. FOR TONIGHT SOME LINGERING SHOWERS/TSTMS WILL CONTINUE
OVER THE HIGHER TERRAIN THRU THE EARLY EVENING HOURS WITH MOST
ACTIVITY ENDING BY MIDNIGHT.
.LONG TERM...FAIRLY STRONG WEST-SOUTHWESTERLY FLOW ALOFT IS PROGGED
OVER THE CWA SUNDAY THROUGH MONDAY NIGHT. THE SYNOPTIC SCALE ENERGY
IS WEAK SUNDAY THROUGH MONDAY NIGHT. THE LOW LEVEL PRESSURE AND
WIND FIELDS SHOW A WEAK COLD FRONT TO MOVE INTO THE PLAINS ON
SUNDAY. WEAK UPSLOPE IS PROGGED FOR THE PLAINS INTO SUNDAY
EVENING. ON MONDAY...THE GRADIENT IS WEAK SO NORMAL DIURNAL WIND
PATTERNS SHOULD PREVAIL. FOR MOISTURE...THEN IS SOME PROGGED
...MAINLY IN THE UPPER AND MID LEVELS ON SUNDAY INTO MONDAY
EVENING. DEW POINT PROGGS ARE MAINLY IN THE 40S F OVER THE PLAINS
...WITH 30S F IN THE MOUNTAINS ON SUNDAY...AND A TAD LOWER ON
MONDAY. THE GFS IS A BIT HIGHER THAN THE NAM. PRECIPITABLE WATER
VALUES ARE IN HE 0.90-1.00 INCH RANGE ON SUNDAY...THEN THE 0.75-0.85
INCH RANGE ON MONDAY. THERE IS A TAD OF CAPE PROGGED OVER THE
MOUNTAINS LATE DAY SUNDAY...NOTHING FOR THE PLAINS. BY LATE DAY
MONDAY...THE NAM ONLY HAS LIMITED CAPE OVER THE MOUNTAINS...WHILE
THE GFS HAS A TAD OVER THE FAR EAST. THE QPF FIELDS HAVE A TAD OF
MEASURABLE RAINFALL PROGGED OVER THE MOUNTAINS LATE DAY SUNDAY.
THERE IS EVEN LESS INDICATED FOR MONDAY. FOR POPS...WILL GO WITH
"CHANCE"S IN THE MOUNTAINS SUNDAY AFTERNOON AND EVENING...NOTHING
FOR THE PLAINS. FOR LATE DAY MONDAY...WILL GO WITH 20% IN THE
MOUNTAINS...10%S ELSEWHERE. CONCERNING FIRE WEATHER...WILL GO WITH
NO HIGHLIGHTS SUNDAY FOR THE PLAINS BECAUSE THE WINDS DON`T SEEM TO
BE AN ISSUE...AND RELATIVE HUMIDITIES WILL BE MARGINAL. IT WILL BE A
BIT COOLER SUNDAY EVEN THOUGH MOISTURE IS NOT GREAT. FOR
TEMPERATURES...SUNDAY`S HIGHS SHOULD BE 1.0-2.5 C COOLER THAN
SATURDAY`S HIGHS. MONDAY`S HIGHS MAY BE A TAD WARMER THAN
SUNDAY`S. FOR THE LATER DAYS...TUESDAY THROUGH FRIDAY...MODELS HAVE
A PRETTY FLAT UPPER RIDGE CENTERED TO THE SOUTH OF COLORADO WITH
MAINLY ZONAL FLOW ALOFT TUESDAY INTO THURSDAY NIGHT. ON FRIDAY...
BOTH THE GFS AND ECMWF SHOW A VIGOROUS UPPER TROUGH MOVING
SOUTHEASTWARD TO OUR NORTH AND NORTHEAST. THE FLOW ALOFT BECOMES
NORTHWESTERLY ON FRIDAY...AND BOTH MODELS SHOW A SIGNIFICANT COLD
FRONT TO MOVE IN THE CWA. THE GFS AND ECMWF ALSO SHOW A WEAKER COLD
FRONT TO MOVE IN ON WEDNESDAY. MOISTURE IS SPARSE FOR ALL THE
DAYS.
&&
.AVIATION...WINDS HAVE REMAINED SOUTH EARLY THIS MORNING AND
SHOULD BE SSW THRU LATE MORNING. BY 18Z LATEST HRRR SHOWS A WK
DENVER CYCLONE NR THE AIRPORT WITH LIGHT NLY WINDS DEVELOPING THRU
21Z. AFTER 21Z THE HRRR SHOWS AN OUTFLOW BNDRY MOVING ACROSS THE
AIRPORT FM CONVECTION OVER THE FOOTHILLS WITH WINDS BECOMING WNW.
COULD BRIEFLY SEE SOME WIND GUSTS TO 25 MPH OR SO WITH THIS BNDRY.
FOR NOW WILL NOT MENTION ANY TSTM ACTIVITY AT DIA. BY EARLY EVENING
WILL SHIFT WINDS BACK TO THE SW AND KEEP THEM THAT WAY OVERNIGHT.
A WK CDFNT WILL MOVE INTO THE AREA AFTER 12Z SUN WITH WINDS
BECOMING NLY BY 15Z.
&&
.HYDROLOGY...WIDELY SCATTERED THUNDERSTORMS WILL BE POSSIBLE IN
THE BURN AREAS THIS AFTERNOON WITH RAINFALL AMOUNTS AROUND A
QUARTER INCH OR LESS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM 11 AM THIS MORNING TO 7 PM MDT THIS
EVENING FOR COZ242-244>246-248>251.
&&
$$
SHORT TERM...RPK
LONG TERM....RJK
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS ALBANY NY
1045 PM EDT SUN SEP 2 2012
.SYNOPSIS...
HIGH PRESSURE WILL KEEP OUR REGION MAINLY DRY THROUGH TONIGHT.
THE REMNANTS OF ISAAC WILL APPROACH THE AREA ON LABOR DAY...BRINGING
AN INCREASE IN CLOUDINESS AND A THREAT OF SHOWERS STARTING MONDAY
NIGHT AND CONTINUING THROUGH THE MID WEEK PERIOD.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 1045 PM EDT...SKIES REMAIN MOSTLY CLEAR ACROSS THE
REGION...WITH THE EXCEPTION OF PATCHY LOW CLOUDS DEVELOPING ACROSS
PORTIONS OF THE LITCHFIELD HILLS. EVENTUALLY...WINDS SHOULD
GRADUALLY VEER MORE INTO THE E/SE...WHICH SHOULD BRING INCREASING
LOW LEVEL MOISTURE BACK INTO THE REGION...ESP AFTER MIDNIGHT. THE
LATEST NAM 12 AND RUC BOTH DEPICT LOW CLOUDS DEVELOPING ACROSS
WESTERN MA AND NW CT AROUND OR SHORTLY AFTER MIDNIGHT...THEN
EXPANDING WEST INTO THE SE CATSKILLS...AND POSSIBLY NORTHWARD
WITHIN THE HUDSON RIVER VALLEY FROM ALBANY SOUTH BY DAYBREAK. WE
HAVE THEREFORE INCREASED THE CLOUD COVERAGE A BIT IN THESE AREAS
LATER TONIGHT...WITH THE PROSPECTS FOR MOSTLY CLOUDY SKIES TOWARD
DAYBREAK. IN ADDITION...PATCHY FOG MAY FORM WITHIN RIVER
VALLEYS...AND ALSO ACROSS HIGHER ELEVATIONS ACROSS THE
GREENS/BERKSHIRES/LITCHFIELD HILLS AFTER MIDNIGHT.
EXPECT OVERNIGHT MINS TO FALL INTO THE 40S AND 50S ACROSS MOST
AREAS FROM THE MOHAWK RIVER VALLEY NORTH INTO THE SOUTHERN
ADIRONDACKS...WITH 50S TO LOWER 60S FURTHER S AND E...WHERE SOME
CLOUDS AND HIGHER LOW LEVEL MOISTURE AMOUNTS SHOULD DEVELOP.
ON LABOR DAY...EXPECT MID AND HIGH CLOUDS TO INCREASE FROM
SOUTHWEST TO NORTHEAST WITH SOME WIDELY SCATTERED SHOWERS
DEVELOPING DURING THE AFTERNOON ACROSS SW PTNS OF THE FA. HIGHS
ARE EXPECTED TO BE IN THE MID 70S TO AROUND 80.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
WHILE QPF AMOUNTS VARY SOME AMONGST THE MODELS...ALL THE GUIDANCE
SUGGESTS THAT THE REMNANTS OF ISAAC WILL IMPACT OUR REGION THROUGH
THE MID WEEK PERIOD WITH INCREASING POPS MONDAY NIGHT ESPECIALLY
DURING THE SECOND HALF OF THE NIGHT AND THEN LIKELY TO CATEGORICAL
POPS TUESDAY INTO WEDNESDAY ALTHOUGH ACTIVITY MAY START TO
DIMINISH BY WEDNESDAY AFTERNOON WITH STEADIER PCPN BECOMING MORE
SCATTERED ESPECIALLY ACRS NW PTNS OF THE FA. THE HEAVIEST PCPN AT
THIS TIME APPEARS TO BE DURING THE TUESDAY AFTERNOON THROUGH
WEDNESDAY MORNING TIME FRAME ACRS THE BULK OF THE REGION. THIS IS
THE PERIOD WHEN THE H10-H8 THETA E RIDGE IS THE STRONGEST ACRS THE
FA SLIDING FORM NW TO SE WITH TIME AS WELL AS PWATS 1.5 TO
SLIGHTLY OVER 2 INCHES.
SPECIFICALLY FOR THE PERIOD FROM MONDAY NIGHT THROUGH
WEDNESDAY...EXPECT CHANCES OF RAIN AND ISOLATED THUNDERSTORMS
TO INCREASE FROM SOUTHWEST TO NORTHEAST ACROSS THE REGION MONDAY
NIGHT. RAIN AND ISOLATED THUNDERSTORMS WITH RAINFALL HEAVY AT
TIMES CONTINUE TUESDAY AND TUESDAY NIGHT. ON WEDNESDAY EXPECT THE
HEAVIEST RAIN IN THE MORNING WITH MORE SCATTERED CONVECTION DURING
THE AFTERNOON. ON WEDNESDAY THERE MAY ALSO BE SOME BREAKS IN THE
OVERCAST WHICH COUPLED WITH SURFACE HEATING AND AN UNSTABLE
AIRMASS STILL IN PLACE WILL INCREASE THE CHANCE FOR
THUNDERSTORMS...SO HAVE CHANCE OF THUNDERSTORMS MENTIONED ON
WEDNESDAY. WHILE THE THUNDERSTORMS ARE NOT EXPECTED TO BE SEVERE
MORE HEAVY DOWNPOURS ARE POSSIBLE. EXPECT LOWS MONDAY NIGHT IN THE
MID 70S TO MID 80S.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A SECONDARY COLD FRONT WILL IMPACT THE FORECAST AREA IN THE WAKE OF
THE MOISTURE ASSOCIATED ISAAC WED NIGHT INTO THU. THE GFS SHOWS
MODEST AMOUNTS OF INSTABILITY WITH SFC DEWPTS IN THE M50S TO L60S.
PWATS REMAIN AROUND AN INCH. THE BEST CHANCE OF SHOWERS AND
THUNDERSTORMS WILL BE WITH THE COLD FRONT THU. MAX TEMPS WILL
GENERALLY BE IN THE M70S TO L80S.
THU NIGHT THRU FRI NIGHT...THE HPC GUIDANCE/GFS/ECMWF SHOW A BREAK
IN THE MID WEEK UNSETTLED WEATHER...WITH HIGH PRESSURE BUILDING IN
FROM THE OHIO VALLEY OVER PA AND THE NORTHEAST. LOWER HUMIDITY
LEVELS AND DRY CONDITIONS WILL PREVAIL BEFORE THE NEXT UPSTREAM
SYSTEM OVER THE CNTRL MS RIVER VALLEY IMPACTS NY AND NEW ENGLAND ON
THE WEEKEND. LOWS WILL BE IN 50S TO L60S THU NIGHT...AND U40S TO
U50S FRI NIGHT. NEAR NORMAL HIGHS ARE EXPECTED ON FRI IN THE M70S
TO NEAR 80F IN THE VALLEYS...AND U60S TO M70S OVER THE HILLS AND
MTNS.
SATURDAY INTO SUNDAY...SOME TIMING DIFFERENCES FOR NEXT WEEKEND WITH
THE EVOLUTION OF THE POSITIVELY TILTED LONGWAVE TROUGH OVER THE ERN
HALF OF THE CONUS AND THE DEVELOPING SW FLOW ALOFT OVER THE ERN
SEABOARD. THE FRONTAL BOUNDARY ON THE LEADING EDGE OF THE UPPER
TROUGH WILL LIKELY HANG TO THE WEST OF THE COASTAL PLAIN WITH
PERHAPS AREAS OF LOW PRESSURE BRINGING SHOWERS/RAINFALL TO THE FCST
AREA BOTH DAYS ON THE WEEKEND. SOME OF THE GUIDANCE WOULD KEEP SAT
DRY...AND SUNDAY MORE UNSETTLED. THIS UPPER TROUGH SHOULD HELP
STEER LESLIE FAR ENOUGH EAST OF NEW ENGLAND FOR NO SIGNIFICANT
IMPACTS. WE TRENDED CLOSER TO THE LATEST HPC GUIDANCE WITH A LOW
CHANCE OF SHOWERS EACH DAY. HIGHS WILL BE SEASONABLE FOR THE 2ND
WEEKEND OF SEPT.
OVERALL...TEMPS WILL TREND SLIGHTLY ABOVE NORMAL...AND PCPN MAY BE
NEAR NORMAL OR SLIGHTLY ABOVE FOR THE EXTENDED.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE WILL MOVE EAST OF MAINE TONIGHT. A WARM FRONT WILL
SLOWLY APPROACH FROM THE OHIO VALLEY AND PENNSYLVANIA TOMORROW.
LOW LEVEL MOISTURE WILL GRADUALLY INCREASE FROM THE SOUTHEAST
LATER THIS EVENING AND OVERNIGHT. THIS SHOULD ALLOW STRATUS/MIST
AND MVFR/IFR CONDITIONS TO DEVELOP THROUGHOUT THE AREA BETWEEN
MIDNIGHT AND DAYBREAK. SOME AREAS OF FOG...ESPECIALLY NEAR
KGFL/PSF MAY FORM LATE TONIGHT AS WELL.
THE LOW STRATUS AND/OR ANY FOG WILL DISSIPATE BTWN 12Z-
15Z/MON...HOWEVER A HIGHER STRATUS DECK WILL INCREASE THROUGHOUT
THE DAY...AS A LOW PRESSURE SYSTEM AND ITS WARM FRONT MOVES INTO
THE AREA.
WINDS THIS AFTERNOON AND TONIGHT WILL BE LIGHT TO CALM AND SHIFT TO
MORE OF A SOUTHEAST DIRECTION AFTER 08Z/MON AT 5-10 KTS. WINDS
MAY BE A BIT STRONGER AT KALB DUE TO FUNNELING EFFECTS UP THE
HUDSON RIVER VALLEY.
OUTLOOK...
MON NIGHT...VFR BECOMING MVFR/IFR. CHC -SHRA AND ISOL -TSRA LATE.
TUE...MVFR/IFR. SHRA LIKELY.
WED-THU...VFR/MVFR. CHC -SHRA/-TSRA.
FRI...VFR...NO SIG WX.
&&
.FIRE WEATHER...
HIGH PRESSURE WILL KEEP OUR REGION MAINLY DRY THROUGH TONIGHT.
THE REMNANTS OF ISAAC WILL APPROACH THE AREA ON LABOR
DAY...BRINGING AN INCREASE IN CLOUDINESS AND A THREAT OF SHOWERS
STARTING MONDAY NIGHT AND CONTINUING THROUGH THE MID WEEK PERIOD.
RELATIVE HUMIDITIES WILL INCREASE TO 80 TO 100 PERCENT
TONIGHT...DROP TO 50 TO 70 PERCENT ON MONDAY...RECOVER TO 100
PERCENT MONDAY NIGHT...AND ONLY DROP TO 70 TO 90 PERCENT ON TUESDAY.
WINDS WILL BE LIGHT AND VARIABLE TONIGHT...AND SOUTH TO SOUTHEAST
MONDAY THROUGH TUESDAY.
&&
.HYDROLOGY...
MAINLY DRY WEATHER IS EXPECTED THROUGH LABOR DAY. THE REMNANTS OF
ISAAC WILL INTERACT WITH A FRONT AND BRING RAIN TO OUR AREA
BEGINNING MONDAY NIGHT AND CONTINUING THROUGH THE MID WEEK PERIOD.
AT THIS TIME THE LATEST MODEL GUIDANCE SUGGESTS A WIDESPREAD 1 TO
3 INCHES OF RAIN WITH LOCALLY HIGHER AMOUNTS OF AROUND 4 INCHES
ACROSS SOUTHEAST PORTIONS OF THE AREA. NO RIVER FLOODING IS FORECAST
AT THIS TIME.
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...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...11/NAS/WASULA
NEAR TERM...KL/11
SHORT TERM...11
LONG TERM...WASULA
AVIATION...KL/WASULA
FIRE WEATHER...11
HYDROLOGY...11
AREA FORECAST DISCUSSION
NWS TAUNTON MA
130 PM EDT SAT SEP 1 2012
.SYNOPSIS...
SEASONABLE TEMPERATURES ARE ON TAP FOR THE HOLIDAY WEEKEND WITH HIGH
PRESSURE GENERALLY IN CONTROL. DRY WEATHER SHOULD DOMINATE THROUGH
LABOR DAY...OTHER THAN A SPOT SHOWER OR TWO. RAIN IS LIKELY TUESDAY
INTO WEDNESDAY AS A COLD FRONT WITH MOISTURE FROM ISAAC/S REMNANTS
MOVES INTO THE REGION. A SECOND COLD FRONT MOVES THROUGH ON
THURSDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1 PM UPDATE...
A FEW SHOWERS HAVE POPPED UP OVER SRN NH AND NW MA IN A WEAK
CONVERGENCE REGION BETWEEN THE NW FLOW IN VT AND NY AND THE E TO
NE FLOW MOVING OVER SRN NEW ENGLAND. RUC DATA DOES SUGGEST THAT
THERE IS SOME VERY WEAK AND VERY LOW LVL INSTABILITY AROUND THE BL
THAT THESE SHOWERS MAY FEED ON THANKS TO THE LIFT PROVIDED BY THE
CONVERGENCE. HAVE KEPT MOSTLY SLIGHT CHANCE POPS W OF WORCESTER
INTO SRN NH AS THE COVERAGE SHOULD GENERALLY REMAIN ISOLATED
THROUGH THE DAY AS DRIER AIR BEGINS TO BUILD OVER FROM THE NW WITH
HIGH PRES. BUT THE UPPER LVL TROF WILL BE MOVING OVER INTO THE
EVENING...WHICH MAY PROLONG THIS CHANCE FOR PRECIP...SO HAVE KEPT
THE SLIGHT CHANCE POPS INTO THE EARLY HOURS OF THE OVERNIGHT.
PREVIOUS DISCUSSION...
THE MAIN STORY WILL BE THE COOLER WEATHER TO START THE WEEKEND
BEHIND THE FRONT...UNDER PARTLY TO MOSTLY SUNNY SKIES. ONSHORE
FLOW SHOULD HOLD HIGH TEMPERATURES IN THE MIDDLE TO UPPER 70S
ALONG THE IMMEDIATE COAST/HIGH TERRAIN...WITH MAINLY LOWER 80S
ELSEWHERE.
A MOISTURE STARVED SHORTWAVE WILL BE DROPPING DOWN IN NORTHWEST FLOW
ALOFT. THERE MAY BE ENOUGH MARGINAL INSTABILITY FOR A BRIEF SPOT
SHOWER OR TWO ACROSS THE INTERIOR THIS AFTERNOON. CONFIDENCE ON
WHETHER ANYTHING CAN DEVELOP IS LOW AND IF IT DOES AREAL
COVERAGE/DURATION WOULD BE QUITE LIMITED. THEREFORE...JUST INCLUDED
A SLIGHT CHANCE POP IN THIS REGION.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
TONIGHT...
LIGHT SOUTHEAST FLOW AT THE SURFACE AND A SHORTWAVE ALOFT MAY BE
ENOUGH TO SPAWN A FEW ISOLATED SHOWERS ACROSS THE INTERIOR.
AGAIN...AREAL COVERAGE/DURATION SHOULD BE LIMITED GIVEN DRY MID
LEVEL AIR...SO WILL JUST INCLUDE A SLIGHT CHANCE POP IN THIS
REGION. LOW TEMPERATURES WILL MAINLY BE IN THE 50S TO NEAR 60. MAY
SEE A BIT OF PATCHY GROUND FOG IN THE TYPICALLY PRONE
LOCATIONS...BUT NOTHING WIDESPREAD IS EXPECTED.
SUNDAY...
ANOTHER MOISTURE STARVED SHORTWAVE WILL BE DROPPING DOWN IN
NORTHWEST FLOW ALOFT. WHILE MUCH OF THE DAY WILL BE DRY AT A GIVE
LOCATION...THERE PROBABLY WILL BE AT LEAST A FEW HIT AND MISS
SHOWERS AROUND THE REGION. WILL RUN WITH SOME 20 TO 30 POPS TO
COVER THIS POTENTIAL...BUT ANY RAINFALL AMOUNTS WILL BE QUITE
LIGHT. HIGH TEMPERATURES WILL BE IN THE 70S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
* RAIN CHANCES INCREASE TUESDAY INTO WEDNESDAY
* ANOTHER COLD FRONT MOVES THROUGH THURSDAY
OVERVIEW...
THE MODELS ARE IN DECENT AGREEMENT THROUGH MUCH OF THE LONG TERM.
THERE ARE SOME SUBTLE DIFFERENCES THROUGHOUT BUT NOTHING THAT
CREATES A LARGE SHIFT IN SENSIBLE WEATHER. FAIRLY QUIET WEATHER
EXPECTED SUNDAY NIGHT AND MONDAY. THE NEXT CHANCE FOR PRECIP WILL
BE TUESDAY AND WEDNESDAY WITH A FRONTAL SYSTEM...AND MOISTURE FROM
ISAACS REMNANTS. THEN ANOTHER COLD FRONT MOVES THROUGH THURSDAY.
HIGH PRESSURE RETURNS FRIDAY.
SUNDAY NIGHT THROUGH MONDAY...HIGH PRESSURE BUILDS INTO SOUTHERN NEW
ENGLAND. TEMPS WILL BE NEAR NORMAL.
MONDAY NIGHT THROUGH WEDNESDAY...CONFIDENCE IS INCREASING IN THIS
PORTION OF THE EXTENDED FORECAST. ALL MODELS HAVE BEEN CONSISTENTLY
INDICATING THE ARRIVAL OF A LOW PRESSURE SYSTEM FROM THE MIDWEST
ALONG WITH MOISTURE FROM THE REMNANTS OF ISAAC. SOUTHERLY FLOW
AHEAD OF THIS COLD FRONT MONDAY NIGHT WILL INCREASE WARM AIR
ADVECTION AND MOISTURE ACROSS THE AREA...BRINGING SHOWERS INTO
WESTERN NEW ENGLAND MONDAY NIGHT. INSTABILITY IS LIMITED SO DO NOT
EXPECT ANY THUNDER MONDAY NIGHT. FOR TUESDAY THROUGH WEDNESDAY...
COPIOUS AMOUNTS OF MOISTURE FROM ISAACS REMNANTS WILL BE MOVING INTO
THE REGION. MODELS HAVE BETWEEN 1 INCH AND 2 AND A HALF INCHES OF
QPF ACROSS MUCH OF SOUTHERN NEW ENGLAND. WHILE IT IS TOO EARLY TO
KNOW EXACTLY HOW THIS WILL EVOLVE...WITH TROPICAL REMNANTS
INVOLVED...IT IS VERY LIKELY THAT THERE WILL BE LOCALLY HEAVY
RAINFALL ACROSS SOUTHERN NEW ENGLAND. HAVE KEPT LOW END LIKELY POPS
IN FOR THE TIME BEING...THESE WILL LIKELY BE RAISED OVER THE NEXT
FEW DAYS.
THURSDAY...ANOTHER COLD FRONT WILL MOVE THROUGH SOUTHERN NEW
ENGLAND. MODELS DIFFER ON WHETHER THIS WILL BE A DRY COLD FRONT OR
IF THERE WILL BE SHOWERS POSSIBLE. WITH THAT UNCERTAINTY IN MIND
WILL KEEP SLIGHT CHANCE TO LOW END CHANCE POPS IN FOR THE TIME
BEING.
FRIDAY...HIGH PRESSURE BUILDS IN BEHIND THE FRONT WITH DRY...
PLEASANT WEATHER EXPECTED.
&&
.AVIATION /17Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
OVERVIEW...HIGH CONFIDENCE.
MAINLY VFR THROUGH SUN NIGHT. MAY HAVE SOME VERY BRIEF MVFR
CONDITIONS IN ISOLATED SHOWERS IN THE W AND SRN NH INTO THE
OVERNIGHT HOURS TONIGHT. MAY BE SOME MVFR/IFR GROUND FOG AT
TYPICALLY PRONE TERMINALS TONIGHT. NE WINDS GRADUALLY DIMINISH
TODAY...BECOME LIGHT AND VRB TONIGHT INTO THE DAY SUN.
KBOS TERMINAL...HIGH CONFIDENCE IN VFR TODAY INTO SUN.
KBDL TERMINAL...HIGH CONFIDENCE IN VFR TODAY INTO SUN.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
SUNDAY NIGHT THROUGH MONDAY...MODERATE TO HIGH CONFIDENCE IN
MOSTLY VFR CONDITIONS. PATCHY MVFR/IFR FOG POSSIBLE SOME NIGHTS AT
THE TYPICALLY PRONE AIRPORTS.
MONDAY NIGHT THROUGH WEDNESDAY...MODERATE TO HIGH CONFIDENCE.
MVFR/IFR CONDITIONS EXPECTED IN SHOWERS/RAIN.
&&
.MARINE...
FORECAST CONFIDENCE MODERATE TO HIGH THROUGH SUNDAY AFTERNOON.
COOL ADVECTION BEHIND THE COLD FRONT WILL YIELD NORTHEAST WIND GUSTS
OF 20 TO 25 KNOTS TODAY. THIS SHOULD RESULT IN SEAS BUILDING TO
AROUND 5 FEET ACROSS THE OUTER-WATERS. THEREFORE...WILL HAVE SCA
HEADLINES FOR SOME OF OUR WATERS TODAY FOR THESE MARGINAL CONDITIONS.
WINDS WILL DIMINISH THIS EVENING...BUT 5 FOOT SEAS WILL LINGER
ACROSS THE SOUTHERN OUTER-WATERS INTO TONIGHT AND POSSIBLY EVEN INTO
EARLY SUNDAY. OTHERWISE...WEAKER PRESSURE GRADIENT SHOULD GENERALLY
KEEP WINDS AND SEAS BELOW SCA THRESHOLDS MOST OF SUNDAY.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
MODERATE TO HIGH CONFIDENCE. HIGH PRESSURE BUILDS OVER THE WATERS
SUNDAY NIGHT AND MONDAY...KEEPING WINDS AND SEAS BELOW SCA
CRITERIA. WINDS AND SEAS INCREASE AGAIN MONDAY NIGHT THROUGH
WEDNESDAY AS A COLD FRONT APPROACHES THE WATERS. RAIN AND FOG ARE
ALSO POSSIBLE DURING THIS TIME FRAME.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR
ANZ231>234-250.
SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...FRANK/RLG
NEAR TERM...FRANK/DOODY
SHORT TERM...FRANK
LONG TERM...RLG
AVIATION...DOODY/RLG
MARINE...FRANK/RLG
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
330 AM EDT SAT SEP 01 2012
.SYNOPSIS...
07Z WATER VAPOR AND H4 RAP ANALYSIS SHOW MUCH OF THE SOUTHEASTERN
CONUS UNDERNEATH A STRONG 592-595DM UPPER RIDGE. AN NWP ADVERTISED
INTRUSION OF VERY DRY MID/UPPER LEVEL AIR IS NOW SEEN QUITE WELL ON
WV IMAGERY ROTATING DOWN THE EASTERN CIRCULATION OF THE UPPER RIDGE
AND BEGINNING TO ARRIVE OVER THE FL PENINSULA. THIS INTRUSION OF
UNSEASONABLY DRY AIR ABOVE THE SURFACE WILL BE THE MAIN PLAYER IN
OUR FORECAST THROUGH THE WEEKEND. THE 00Z KTBW SOUNDING PROFILE
STILL SHOWED A PW OF AROUND 1.8" (WHICH IS RIGHT ABOUT WHERE WE
SHOULD BE FOR THIS TIME OF YEAR)...HOWEVER THE INFLUENCE OF THE
UPPER RIDGE CAN BE SEEN IN WARM 500MB TEMPS OF -4C TO -5C. THESE
TEMPS HELPED TO PARTIALLY CAP THE COLUMN AND KEPT CONVECTIVE
COVERAGE ON FRIDAY TO A MINIMUM.
AT THE SURFACE...THE SUBTROPICAL RIDGE AXIS IS ALIGNED JUST TO OUR
NORTH NEAR THE I-10 CORRIDOR RESULTING IN A LIGHT NORTHEAST TO
EASTERLY LOW LEVEL FLOW.
CONDITIONS ARE DRY OUT THERE WITH LITTLE TO NO ACTIVITY SEEN ON
REGIONAL RADARS...AND SKIES ARE TRENDING TOWARDS CLEAR FROM NE TO SW
AS THE DRIER AIR ARRIVES ALOFT.
&&
.SHORT TERM (TODAY THROUGH MONDAY)...
TODAY...THE MID/UPPER RIDGE WILL CONTINUE OVERHEAD BUT SLOWLY WEAKEN
THROUGH THE DAY ALLOWING HEIGHTS TO COME DOWN A FEW DM. OVERALL WILL
SEE A DROP IN THE SYNOPTIC SUPPRESSION ON THE COLUMN...HOWEVER THE
ARRIVAL OF INCREASINGLY DRY AIR ABOVE 700MB WILL ACT TO
SIGNIFICANTLY LIMIT CONVECTION. CROSS-SECTIONS ALONG THE FL WEST
COAST SHOW THIS TONGUE OF DRIER AIR DESCENDING DOWN THROUGH THE
COLUMN AS WE HEAD INTO THE AFTERNOON MAKING ANY CONVECTION THAT DOES
FIRE ALONG THE SEA-BREEZE RATHER SHALLOW. DID GO WITH A 20% SLIGHT
CHANCE POP FOR THESE ISOLATED CELLS...HOWEVER THE COVERAGE OF
RAINFALL TODAY WILL LIKELY BE EVEN LOWER THAN THIS. WITH EASTERLY
LOW LEVEL FLOW...THE SEA-BREEZE WILL ONCE AGAIN BE PINNED TO THE
COAST. THE LACK OF DEVELOPING ONSHORE FLOW AND THE STACKED RIDGING
SHOULD ALLOW TEMPERATURES TO EASILY CLIMB INTO THE LOWER/MIDDLE 90S.
TONIGHT...ANY ISOLATED CONVECTIVE CELLS WILL PUSH OFFSHORE DURING
THE EVENING HOURS LEAVING A DRY FORECAST FOR OUR LAND ZONES.
TEMPERATURES WILL ACTUALLY BECOME RATHER COMFORTABLE FOR THIS TIME
OF YEAR...WITH SOME OF THE NORMALLY COOLER MOS STATIONS SHOWING
POTENTIAL FOR LOWS AROUND 70.
SUNDAY...UPPER RIDGE OVERHEAD WILL CONTINUE TO WEAKEN IN RESPONSE TO
A STRONG SHORTWAVE TROUGH DROPPING SOUTHEASTWARD OUT OF THE TN
VALLEY...AND A CLOSED UPPER LOW APPROACHING THE PENINSULA FROM THE
EAST. MUCH OF SUNDAY LOOKS LIKE YET ANOTHER DAY WITH AN UNSEASONABLY
DRY COLUMN OVER OUR HEADS. IN FACT...THE DEPTH OF THE DRY AIR IS
SHOWN BY MANY OF THE GUIDANCE MEMBERS TO BE MAXIMIZED DURING THE
DAYLIGHT HOURS OF SUNDAY. THIS EXCESSIVELY DRY COLUMN ABOVE 850MB
WILL BE OF GREATEST INFLUENCE OVER THE CENTRAL AND NORTHERN PORTIONS
OF THE FORECAST AREA. DOWN TOWARD FORT MYERS...SOME RECOVERY IN THE
MOISTURE FIELDS IS LIKELY BY LATE AFTERNOON IN CLOSER PROXIMITY TO
THE APPROACHING UPPER LOW. IF AN ISOLATED SHOWER OR 2 IS TO FORM
SUNDAY AFTERNOON...IT WOULD BE DOWN TOWARD THIS MOISTURE RETURN. THE
REMAINDER OF THE FORECAST AREA WILL BE UNDER A VERY HOSTILE
ENVIRONMENT FOR DEEP CONVECTION...AND WILL LEAVE POPS AT 10% OR
LESS.
MONDAY...UPPER LOW FEATURE IS PROGGED BY THE GLOBAL GUIDANCE TO
BECOME CENTERED OVER THE SOUTHERN FL PENINSULA BY MONDAY EVENING.
HIGHEST RAIN CHANCES (30-40%) WILL EXIST SOUTH OF THE TAMPA BAY AREA
WHERE THE SYNOPTIC SUPPORT FOR LIFT AHEAD OF THE LOW CENTER AND
COOLEST ARRIVING MID-LEVEL TEMPERATURES WILL EXIST. FROM TAMPA BAY
NORTHWARD...THESE INFLUENCES WILL BE LESS...AND AT LEAST SOME
RESIDUAL DRY AIR ALOFT WILL STILL BE IN PLACE. WILL INTRODUCE SLIGHT
CHANCE POPS BACK TO THE FORECAST...BUT REALLY ANTICIPATE ANOTHER DRY
DAY. THE UPPER LOW AND ASSOCIATED BETTER RAIN CHANCES WILL MIGRATE
NORTHWARD BY TUESDAY. A MID-LEVEL COLD POOL UNDERNEATH THE UPPER LOW
(-8 TO -10C) WILL BE SPREADING OVER THE SOUTHERN THIRD OF THE
PENINSULA BY LATE MONDAY. THIS ENHANCED INSTABILITY WILL BRING THE
POTENTIAL FOR A FEW STRONGER STORMS OVER THE SOUTHERN THIRD OF THE
FORECAST AREA.
&&
.LONG TERM (MONDAY NIGHT - FRIDAY)...WE WILL TRANSITION BACK INTO A
WETTER WEATHER PATTERN DURING THE EXTENDED TIME FRAME AS THE RIDGE
OF HIGH PRESSURE WEAKENS AND A TROPICAL UPPER-TROPOSPHERIC TROUGH
/TUTT/ AND ITS ASSOCIATED LOW PRESSURE AREA MOVE WESTWARD TOWARD THE
PENINSULA. BOTH THE GFS AND ECMWF SHOW THIS LOW APPROACHING SOUTH
FLORIDA MONDAY NIGHT AND TUESDAY. THE GFS THEN HOLDS THIS FEATURE
TOGETHER BETTER THAN THE ECMWF...LIFTING IT SLOWLY NORTHWARD OVER
FLORIDA THROUGH WEDNESDAY OR WEDNESDAY NIGHT. THE TUTT LOW THEN GETS
PICKED UP BY A BROAD TROUGH DIGGING EASTWARD TOWARD THE ATLANTIC
COAST. DURING THIS TIME...A FRONTAL BOUNDARY IS FORECAST TO DROP
INTO THE SOUTHEASTERN STATES...PUSHING THE SUB-TROPICAL RIDGE TO OUR
SOUTH AND TURNING OUR WINDS MORE WESTERLY FOR THURSDAY AND
ESPECIALLY FRIDAY. IN SHORT...MOISTURE WILL BE INCREASING AS THE
TUTT LOW APPROACHES. COOLER MID-LEVEL TEMPS AND LOWER 500MB HEIGHTS
WILL BE MOVING IN FROM THE EAST. OUR EASTERLY WINDS RELAX ENOUGH TO
ALLOW SEA BREEZES TO PUSH INLAND A WAYS TUESDAY AND WEDNESDAY...
FOLLOWED BY STRONGER WESTERLY FLOW DEVELOPING THURSDAY AND FRIDAY.
ALL OF THESE FACTORS SUGGEST RAIN CHANCES WILL INCREASE TO AT LEAST
NORMAL LEVELS...WHICH WOULD BE AROUND 40 TO 50 PERCENT FOR THE FIRST
PART OF SEPTEMBER.
FOR THE FORECAST...LOOK FOR THE BEST RAIN CHANCES TO BE ALONG AND
EAST OF I-75 ON TUESDAY AS SEA BREEZES MOVE ONLY SLOWLY INLAND. BY
WEDNESDAY...THE RIDGE IS BREAKING DOWN SO BEST RAIN CHANCES BEGIN TO
SHIFT INLAND DURING THE AFTERNOON. FOR THURSDAY AND
FRIDAY...WESTERLY FLOW WILL PUSH OUR SEA BREEZE RAPIDLY INLAND AND
TOWARD THE EAST COAST DURING THE AFTERNOON. OTHER THAN SOME SHOWERS
NEAR THE COAST EACH MORNING...THE BEST RAIN CHANCES WILL BE WELL
INLAND DURING THE AFTERNOON. TEMPERATURES WILL RUN WITHIN A COUPLE
DEGREES OF NORMAL FOR THIS TIME OF YEAR.
&&
.AVIATION...
VFR NEXT 24 HOURS. VERY ISOLATED AFTERNOON SHOWERS OR STORMS ARE
POSSIBLE...BUT OVERALL COVERAGE TOO LOW TO MENTION IN TAFS AT THIS
TIME.
&&
.MARINE...
THE SUBTROPICAL RIDGE AXIS WILL HOLD IN POSITION OF THE NORTHEAST
GULF OF MEXICO THROUGH THE WEEKEND AND THEN SETTLE SLOWLY SOUTHWARD
INTO THE MIDDLE PORTION OF NEXT WEEK. THE CLOSE PROXIMITY OF THE
RIDGE AXIS WILL KEEP WINDS AND SEAS BELOW HEADLINE CRITERIA THROUGH
THE FORECAST PERIOD.
&&
.FIRE WEATHER...
HIGH PRESSURE TO OUR NORTH TODAY WILL SETTLE SOUTHWARD INTO THE
REGION DURING THE SECOND HALF OF THE WEEKEND...AND THEN REMAIN IN
PLACE THROUGH AT LEAST TUESDAY. RAIN CHANCES AND LOW LEVEL MOISTURE
WILL BE LOWER THAN NORMAL FOR EARLY SEPTEMBER DURING THE NEXT COUPLE
OF DAYS...HOWEVER NO SIGNIFICANT FIRE WEATHER CONCERNS ARE
ANTICIPATED.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 92 75 91 75 / 20 10 10 10
FMY 92 73 92 75 / 20 10 10 10
GIF 93 71 93 71 / 10 10 10 0
SRQ 91 73 89 73 / 20 10 10 10
BKV 92 70 91 68 / 20 10 10 10
SPG 93 79 91 78 / 20 10 10 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
326 AM EDT SAT SEP 1 2012
.DISCUSSION...
...RIP CURRENT RISK INCREASING THIS WEEKEND...
CURRENT...
N/NE PENINSULA FLOW REGIME DUE TO A DEEP ANTICYCLONE CENTERED OVER
THE DEEP SOUTH AND EXTENDING INTO THE CENTRAL GOMEX. EVENING
SOUNDINGS SHOWED A SIMILAR PROFILE STATEWIDE: MODERATE TO HIGH PWAT
VALUES BTWN 1.7"-2.0" BUT DISTRIBUTED THRU THE COLUMN MORE OR LESS
EVENLY...FAIRLY DRY MID LYRS WITH DEWPOINT DEPRESSIONS GENERALLY ABV
5C AND IN MANY LYRS WELL OVER 10C...VERY WEAK MID LVL LAPSE RATES
BTWN 5.0-5.5C/KM...H70 TEMPS ARND 10C...H50 TEMPS ARND -6C.
LATEST RAP ANALYSIS SHOWS LITTLE IN THE WAY OF MOISTURE OR DYNAMIC
LIFT: H100-H70 MEAN RH AOB 70PCT...H85-H50 MEAN RH BTWN 70-80PCT BUT
WITH VALUES BLO 50PCT ADVECTING ONSHORE...WEAK PVA DUE TO A THIN
BAND OF MID LVL VORTICITY OFFSHORE EMBEDDED WITHIN DEEP NE
FLOW...UPR LVL WIND PATTERN NEUTRAL OR WEAKLY CONVERGENT. RADAR
DETECTING ISOLD SHRAS NOTED OVER THE GULF STREAM ADVECTING ONSHORE S
OF FT. PIERCE INLET.
TODAY/TONIGHT...
DRY/STABLE NE FLOW PATTERN WILL CONTINUE THRU DAWN SUNDAY AS THE
ANTICYCLONE TO THE N RETROGRADES INTO THE GOMEX. FCST WILL BE
LARGELY DRY ONCE AGAIN AS THE AIRMASS IS TOO STABLE ALOFT TO SUPPORT
ANY MEANINGFUL VERTICAL MOTION. ONLY MESOSCALE BNDRY COLLISIONS OR
CONVECTIVE TEMPS COULD DO THIS. HOWEVER...THE NE FLOW WILL ENSURE
MOST BNDRY COLLISIONS WOULD OCCUR OVER W FL...WHILE MID/UPR LVL
DRY AIR ADVECTION WOULD EVAPORATE ANY CU TOWERS LONG BEFORE THEY
COULD BUILD ENOUGH TO SUPPORT PRECIP.
ONE PSBL EXCEPTION WOULD BE THE TREASURE COAST S OF KVRB WHERE A LOW
LVL POCKET OF MOISTURE N OF THE BAHAMAS COULD ALLOW A FEW BRIEF
SHRAS TO PUSH ONSHORE. HOWEVER...THESE SHOULD DISSIPATE ARND
SUNRISE AS LAND/SEA SFC/LOW LVL WND SPEEDS BECOME DIVERGENT WITH
THE FORMATION OF THE EAST COAST SEA BREEZE. FURTHERMORE...GIVEN
THE OVERALL WEAK DYNAMIC SUPPORT...ANY SHRAS THAT MIGHT MAKE IT
ONSHORE WOULD DISSIPATE RAPIDLY AND WOULD HAVE NEGLIGIBLE IMPACT.
DEEP ONSHORE FLOW WILL KEEP MAX TEMPS WITHIN A DEG OR TWO OF CLIMO
AVG (U80S/L90S)...MIN TEMPS A FEW DEG ABV AVG (M70S).
SUN-MON...
AXIS OF SURFACE HIGH PRESSURE RIDGE WILL EXTEND NORTH OF THE AREA
WHICH WILL RESULT IN A LIGHT ONSHORE FLOW BOTH DAYS. UPPER LEVEL
RIDGE AXIS WILL EXTEND NORTH OF THE AREA ON SUNDAY...WHILE UPPER
LEVEL LOW DRIFTS WEST ACROSS THE NORTHERN BAHAMAS. ZONE OF UPPER
LEVEL CONVERGENCE BETWEEN THESE FEATURES WILL PROVIDE
SUBSIDENCE/DRYING AND IT LOOKS TOO DRY FOR ANY RAIN OVER LAND.
THE GFS HAS TRENDED FARTHER WEST WITH THE UPPER LEVEL LOW ON MON
AND NOW MOVES IT TO NEAR THE SOUTHEAST FLORIDA COAST. WITH COLDER
TEMPS ALOFT AND SLIGHTLY INCREASED MOISTURE IN OUR FAR SOUTHERN
COUNTIES...HAVE ADDED A 20 PERCENT POP. THE NORTHERN HALF SHOULD
REMAIN DRY THOUGH WITH PRECIPITABLE WATER A LITTLE BIT EITHER
SIDE OF AN INCH.
MAX TEMPS WILL CONTINUE IN THE LOWER 90S INLAND AND UPPER 80S
ALONG THE COAST. THE DRIER AIR ACROSS THE NORTH WILL KEEP
AFTERNOON RH VALUES LOWER THAN RECENT DAYS.
A SMALL LONG PERIOD SWELL FROM DISTANT TROPICAL CYCLONE KIRK
SHOULD AFFECT THE COASTAL WATERS SUNDAY. THE LATEST WAVE WATCH
MODEL RUN SHOWS A SMALL SWELL FROM DISTANT TROPICAL CYCLONE LESLIE
REACHING THE WATERS LATE MON. THIS WILL LIKELY RESULT IN A
MODERATE TO HIGH RISK OF DANGEROUS RIP CURRENTS.
TUE-SAT...
AT THE SURFACE...A HIGH PRESSURE RIDGE AXIS WILL SETTLE SLOWLY
SOUTH AS FRONTAL TROUGH MOVES INTO THE SOUTHEAST STATES DURING MID
WEEK. THE RIDGE AXIS SHOULD PUSH INTO THE SOUTHERN PENINSULA BY
WED.
THE UPPER LEVEL LOW IS ONLY FORECAST TO DRIFT SLOWLY NORTH THROUGH
LATE WEEK. DEEP LAYER MOISTURE DOES NOT LOOK VERY HIGH...BUT WITH
COOLER TEMPS ALOFT...EXPECT SCATTERED AFTERNOON STORMS ACROSS ALL
AREAS BY WED. STEERING LEVEL FLOW WILL ATTAIN A WESTERLY COMPONENT
AND CONTINUE THE 30-40 PERCENT POPS THROUGH LATE WEEK.
SWELLS FROM SLOW MOVING TROPICAL CYCLONE LESLIE WILL LIKELY
CONTINUE THROUGH THE END OF THE WEEK AND PRODUCE A HIGH RISK OF
DANGEROUS RIP CURRENTS.
&&
.AVIATION...
ALL SITES VFR UNLESS OTHERWISE NOTED: THRU 01/12Z...KFPR-KSUA BRIEF
MVFR CIGS/VSBYS IN ISOLD PASSING SHRAS...N OF KISM-KDAB LCL MVFR
VSBYS IN BR.
&&
.MARINE...
TODAY-TONIGHT...RIDGE AXIS CENTERED OVER THE DEEP SOUTH WILL
GENERATE A GENTLE TO MODERATE NE BREEZE. SEAS GENERALLY AOB 2FT.
THE LEADING EDGE OF A LARGE SWELL TRAIN GENERATED BY DISTANT T.C.
KIRK MAY REACH THE OFFSHORE LEG IN THE PREDAWN HRS OF SUNDAY
MRNG...PUSHING SEAS UP TO 2-3FT. BRIEF ISOLD NOCTURNAL SHRAS OVER
THE GULF STREAM S OF SEBASTIAN INLET.
SUN-MON...HIGH PRESSURE RIDGE AXIS JUST NORTH OF THE WATERS WILL
PROVIDE A LIGHT ONSHORE WIND FLOW. THERE IS A SMALL CHANCE FOR
SHOWERS OR STORMS ACROSS THE SOUTHERN WATERS...MAINLY ON MON.
TRAVERSING INLETS DURING THE OUTGOING TIDE MAY BECOME HAZARDOUS FOR
SMALL CRAFT DUE TO A SMALL LONG PERIOD SWELL FROM DISTANT TROPICAL
CYCLONES KIRK AND LESLIE.
TUE-WED...HIGH PRESSURE RIDGE AXIS WILL SETTLE OVER THE WATERS
TUE AND THEN INTO SOUTH FLORIDA WED...LEADING TO A MORE SOUTHERLY
FLOW BECOMING SOUTHWEST ON WED. WIND SPEEDS SHOULD BE 10 KNOTS OR
LESS. SCATTERED AFTERNOON STORMS ARE EXPECTED TO START PUSHING
BACK ACROSS THE COAST ON WED.
TRAVERSING INLETS DURING THE OUTGOING TIDE WILL BE HAZARDOUS FOR
SMALL CRAFT DUE TO BUILDING LONG PERIOD SWELL FROM DISTANT
TROPICAL CYCLONE LESLIE.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 89 74 89 70 / 10 10 10 10
MCO 92 74 92 70 / 10 10 10 10
MLB 89 74 87 72 / 10 10 10 10
VRB 88 75 87 71 / 10 10 10 10
LEE 93 74 93 71 / 10 10 10 10
SFB 92 74 91 71 / 10 10 10 10
ORL 92 74 91 72 / 10 10 10 10
FPR 88 75 87 72 / 10 10 10 10
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...BRAGAW
LONG TERM....LASCODY
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
323 AM CDT SAT SEP 1 2012
.DISCUSSION...
349 PM CDT
MAIN FORECAST CONCERNS THIS FORECAST PERIOD REVOLVE AROUND PRECIP
CHANCES AND TRENDS...POSSIBLE HEAVY AT TIMES...THIS WEEKEND INTO
THE START OF NEXT WEEK AS REMNANTS OF TROPICAL STORM ISAAC WORK
ITS WAY NORTH ACROSS THE REGION.
IN THE NEAR TERM...LATEST SATELLITE IMAGERY DEPICTING EXPANSIVE
AREA OF MID AND HIGH LEVEL CLOUD COVER CONTINUING TO SPREAD
NORTHWARD ACROSS MUCH OF THE REGION AS THIS SYSTEM SLOWLY MOVES
NORTH. DESPITE AN INCREASE IN CLOUD COVER TODAY...MOSTLY SUNNY TO
PARTLY CLOUDY SKIES HAVE BEEN OBSERVED WITH TEMPERATURES RISING TO
THE LOWER 90S ACROSS NORTHERN ILLINOIS AND MID TO UPPER 80S ACROSS
AREAS SOUTH OF INTERSTATE 80. DESPITE LATEST RADAR IMAGERY SHOWING
SOME WEAK RETURNS FROM THE OUTER BANDS OF THIS SYSTEM ACROSS AREAS
FROM PONTIAC IN ILLINOIS EAST TO FOWLER IN INDIANA...MOST OF THIS
IS NOT REACHING THE GROUND. SOME DRIER AIR IS HELPING WITH THIS
BUT WITH A VERY MOIST AIRMASS ON ITS WAY...IT SHOULDNT TAKE MUCH
LONGER THIS EVENING BEFORE IT STARTS REACHING THE GROUND. OUTSIDE
OF THIS SYSTEM TO THE SOUTH...A COLD FRONT HAS BEEN DROPPING SOUTH
THROUGH PORTIONS OF WISCONSIN TODAY. ALTHOUGH...EXPECT THIS FRONT
TO LOSE ITS SOUTHWARD MOMENTUM THIS EVENING AND THEN BECOME MORE
DIFFUSE AS THE SYSTEM TO THE SOUTH MOVES INTO THE AREA. DESPITE
THIS FRONT ACROSS THE REGION...ANY VERTICAL DEVELOPMENT HAS BEEN
LIMITED AND IS EXPECTED TO REMAIN THIS WAY AS A MORE SUBSIDENT
LARGE SCALE ENVIRONMENT REMAINS OVER THIS BOUNDARY.
SHIFTING TOWARD MAIN FOCUS OF THIS FORECAST PERIOD...REMNANTS OF
TROPICAL STORM ISAAC CONTINUE TO SLOWLY SHIFT NORTH THROUGH
MISSOURI THIS AFTERNOON. THIS SYSTEM IS MARKED WITH A VERY MOIST
ENVIRONMENT...OR A TROPICAL ENVIRONMENT. COPIOUS AMOUNTS OF
MOISTURE WITH 12Z SOUNDINGS ACROSS MISSOURI INDICATING PWATS
AROUND 2.4 INCHES THIS MORNING...AND LATEST RUC ANALYSIS SHOWING
THIS AXIS OF HIGHER PWATS EXTENDING FROM THE ST. LOUIS AREA BACK
SOUTH THROUGH MISSOURI INTO ARKANSAS. WITH A SLOW MOVEMENT OF THIS
SYSTEM TONIGHT...THIS AXIS OF HIGHEST MOISTURE WILL ALSO SHIFT
SLOWLY. NONETHELESS...THESE OUTWARD BANDS OF THIS SYSTEM AND
HIGHER MOISTURE CONTENT AIR WILL LIFT NORTH OVERNIGHT. THIS SHOULD
HELP BRING SHOWERS ACROSS THE SOUTHERN CWA PRIMARILY FOR AREAS
ALONG AND SOUTH OF A LINE FROM PONTIAC IN ILLINOIS TO RENSSELAER
IN INDIANA. HEAVIER DOWNPOURS ARE NOT EXPECTED TONIGHT AS WELL AS
ANY THUNDER. DESPITE SOME INSTABILITY IN PLACE...THESE INITIAL
SHOWERS WILL BE WEAKLY FORCED. ITS NOT UNTIL SATURDAY THROUGH THE
REMAINDER OF THE WEEKEND THAT THE MAIN AXIS OF HIGHEST MOISTURE
AND RAINFALL WILL REACH THE CWA. WITH BETTER FORCING WITH THIS
SYSTEM SHIFTING NORTH AND SREF GUIDANCE INDICATING THAT THE AXIS
OF HIGHER PWATS/MUCH HIGHER DEWPOINT AIR WILL REACH THE SOUTHERN
CWA...THE POTENTIAL FOR HEAVIER RAIN WILL INCREASE. DESPITE SOME
MODEL VARIABILITY WITH THE OVERALL EVOLUTION OF THIS
SYSTEM...CONFIDENCE IS HIGH FOR AREAS ALONG AND SOUTH OF
INTERSTATE 80 TO RECEIVE THE HIGHEST AMOUNTS OF RAIN THIS WEEKEND.
WHERE CONFIDENCE IS LOWER AT THIS TIME IS IN REGARDS TO HOW FAR
NORTH THIS RAIN WILL WORK ITS WAY NORTH. AS A FAIRLY TIGHT
GRADIENT IS EXPECTED WITH THIS PRECIP SHIELD THIS WEEKEND...HAVE
TRIED TO CONVEY THIS AS BEST AS POSSIBLE IN THE GRIDS. IF THIS
SYSTEM WERE TO SHIFT NORTHWARD THAN PREVIOUSLY THOUGHT...THEN THIS
AXIS OF RAINFALL WOULD OF COURSE SHIFT NORTH ACROSS THE CWA. AT
THIS POINT IT APPEARS THAT A DRASTIC CUTOFF IN PRECIP SHOULD OCCUR
AROUND THE I88 CORRIDOR. IN ALL AREAS ACROSS OUR CWA ARE EXPECTED
TO RECEIVE A LARGE AMOUNT OF RAINFALL THROUGH SUNDAY NIGHT...WITH
THE POTENTIAL FOR AMOUNTS OF 4 TO 5 INCHES OR GREATER ALONG AND
SOUTH OF A LINE FROM THE PONTIAC AREA TO THE RENSSELAER AREA.
MOVING NORTH OF THIS LINE...RAINFALL AMOUNTS ARE EXPECTED TO TAPER
FROM AROUND 3 TO 4 INCHES TO AROUND 1 INCH JUST NORTH OF THE
INTERSTATE 80 CORRIDOR. EXPECTED AMOUNTS ALONG THE INTERSTATE 88
CORRIDOR WILL ROUGHLY RANGE FROM THREE QUARTERS OF AN INCH UP TO
ONE INCH...WITH THE POTENTIAL FOR LITTLE OR NO RAIN IN THE
COUNTIES BORDERING WISCONSIN...GENERALLY UNDER A QUARTER INCH. NO
HEADLINES AT THIS TIME BUT WILL CONTINUE THE ESF TODAY.
RODRIGUEZ
&&
.HYDROLOGY...
427 PM CDT
EXPECTED RAINFALL AND POTENTIAL FOR HEAVY RAINFALL...POTENTIALLY
FOR PERIODS OF TIME...ACROSS PORTIONS OF THE CWA STILL ON TRACK
LATE TONIGHT THROUGH THE END OF THE WEEKEND. LATEST OBSERVATIONAL
DATA STILL INDICATING A GOOD SWATH OF MOISTURE JUST SOUTH OF THE
CWA THIS AFTERNOON...WITH LATEST GUIDANCE INDICATING THIS HIGHER
MOISTURE CONTENT AIR TO CONTINUE SPREADING NORTHWARD TONIGHT INTO
SATURDAY. AS THIS SLUG OF MOISTURE MOVES ACROSS THE CWA EARLY
SATURDAY...IT WILL THEN LINGERING THROUGH THE REMAINDER OF THE
WEEKEND. ALTHOUGH...LATEST GUIDANCE CONTINUES TO INDICATE THAT THE
HIGHEST RAIN RATES/RAINFALL SHOULD STAY ACROSS THE SOUTHERN CWA
WHICH SEEMS TO BE ON TRACK. THE POTENTIAL FOR RAINFALL AMOUNTS OF
4 TO 5 INCHES OR GREATER ALONG AND SOUTH OF A LINE FROM THE
PONTIAC AREA TO THE RENSSELAER AREA SEEM TO BE ON TRACK FOR THIS
WEEKEND. MOVING NORTH OF THIS LINE...RAINFALL AMOUNTS ARE EXPECTED
TO TAPER FROM AROUND 3 TO 4 INCHES TO AROUND 1 INCH JUST NORTH OF
THE INTERSTATE 80 CORRIDOR. EXPECTED AMOUNTS ALONG THE INTERSTATE
88 CORRIDOR WILL ROUGHLY RANGE FROM THREE QUARTERS OF AN INCH UP
TO ONE INCH...WITH THE POTENTIAL FOR LITTLE OR NO RAIN IN THE
COUNTIES BORDERING WISCONSIN...GENERALLY UNDER A QUARTER INCH.
DESPITE THE EXPECTED HIGHER RAINFALL THIS WEEKEND...ONLY MINOR
RISES IN AREAS RIVERS ARE EXPECTED WITH NO MAJOR PROBLEMS EXPECTED
AT THIS TIME. A WORST CASE SCENARIO AT THIS TIME BASED ON CURRENT
FORECASTS WOULD BE FOR RIVERS THAT RECEIVE THESE HIGHER AMOUNTS TO
RISE TO MINOR OR JUST ABOVE MODERATE STAGES. ALTHOUGH WOULD LIKE
TO REITERATE SOME UNCERTAINTY WITH THIS SYSTEMS OVERALL
EVOLUTION...THAT EXTENDS INTO THE POTENTIAL RISES. WITH THIS IN
MIND...THIS SITUATION NEEDS TO CONTINUE TO BE CLOSELY MONITORED
THIS WEEKEND AS IT WOULD NOT BE OUT OF THE QUESTION FOR LOCALIZED
AREAS OF HIGHER AMOUNTS AND THUS POSSIBLE HIGHER RISES. SOMETHING
ELSE TO KEEP IN MIND THIS WEEKEND IS THE OVERALL SOIL CONDITIONS
ACROSS THE AREA. WITH A DRY/HARD SOIL IN PLACE...IT WOULD NOT TAKE
MUCH TIME FOR HIGH RAINFALL RATES TO QUICKLY TURN INTO RUNOFF.
ONCE AGAIN...HAVE NOT ISSUED ANY FLOOD HEADLINES AT THIS TIME.
ALTHOUGH...CONTINUE TO MONITOR LATEST UPDATES THIS WEEKEND AS THIS
COMPLEX SYSTEM UNFOLDS ACROSS THE REGION.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* NORTHEAST WINDS WITH GUSTS ABOVE 15 KTS TODAY BECOMING MORE
EASTERLY TONIGHT.
* TIMING OF RAIN AFFECTING TODAY/TONIGHT.
* POTENTIAL FOR MVFR CIG/VIS IF RAIN PERSISTS.
RATZER
//DISCUSSION...UPDATED 06Z...
TROPICAL DEPRESSION ISAAC WAS LOCATED OVER WEST CENTRAL MISSOURI
AT 05Z...WITH AN AREA OF MODERATE RAIN EXTENDING FROM FAR EASTERN
KANSAS ACROSS NORTHERN MISSOURI INTO MUCH OF CENTRAL/SOUTHERN IL.
ISAAC IS EXPECTED TO DRIFT VERY SLOWLY EAST INTO SOUTHERN IL
THROUGH SUNDAY MORNING. MAIN FORECAST QUESTION FOR THE TAFS IS
WHERE THE NORTHERN PERIPHERY OF THE RAIN ASSOCIATED WITH THIS
SYSTEM LAYS OUT IN RELATION TO THE TERMINAL LOCATIONS...AND THE
POTENTIAL FOR MVFR OR EVEN IFR CIG/VIS CONDITIONS IN THE AREAS
WHICH SEE PERSISTENT RAINFALL. 00Z HIGH RESOLUTION MODEL GUIDANCE
SUGGESTS THAT THE NORTHERN EDGE OF THE RAIN AREA WILL BE
APPROXIMATELY THROUGH THE INTERSTATE 88 CORRIDOR ACROSS NORTHERN
IL WITH AREAS TO THE NORTH LESS LIKELY TO SEE PERSISTENT RAIN AND
ASSOCIATED CIG/VIS REDUCTIONS. THIS MAKES FOR A TRICKY FORECAST
WITH TERMINALS IN/NEAR THE EXPECTED SHARP GRADIENT OF LITTLE/NO
RAIN TO THE NORTH AND CONSIDERABLE RAIN FARTHER TO THE SOUTH.
RFD WILL HAVE THE LOWEST LIKELIHOOD OF SEEING ANY PROLONGED PERIOD
OF RAIN AND LOWER CIG/VIS...WITH AN EXPECTATION THAT ORD/DPA WILL
PERHAPS SEE A FEW PERIODS OF LIGHTER RAIN AND GYY FARTHEST TO THE
SOUTH WOULD HAVE THE GREATEST THREAT OF LONGER DURATION RA/SHRA
AND ALSO LOWER CIG/VIS CONDITIONS. FOR NORTHERN TERMINALS...THE
GREATEST POTENTIAL FOR SOME RAIN TO AFFECT RFD/DPA/ORD/MDW WOULD
BE DURING THE AFTERNOON HOURS AS LOW/MID LEVEL MOISTURE CONVERGENCE
EXPANDS NORTHEASTWARD PER MODELS. HIGH-RES GUIDANCE INDICATES SOME
SHOWERS MAY AFFECT GYY AS EARLY AS THIS MORNING...WITH SOME WEAK
RADAR ECHOES ALREADY DEVELOPING SOUTH OF THE KANKAKEE RIVER VALLY
INTO INDIANA.
WINDS ARE EXPECTED TO REMAIN EAST-NORTHEAST THROUGH THE PERIOD AS
THE SURFACE LOW PRESSURE CIRCULATION MOVES SLOWLY ACROSS MISSOURI
AND DOWNSTATE IL. SOME GUSTS INTO THE 15-20 KT RANGE APPEAR
POSSIBLE MAINLY DURING THE DAY TODAY...THOUGH WEAK LOW LEVEL LAPSE
RATES SUGGEST GUSTS MAY BE SOMEWHAT SPORADIC.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN WIND TRENDS. MEDIUM CONFIDENCE GUST SPEEDS.
* MEDIUM CONFIDENCE IN RAIN POTENTIAL AND CIG/VIS TRENDS.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...OCCASIONAL RA. MVFR PSBL IFR CIGS.
MONDAY...CHC RA ISO TSRA. MVFR PSBL.
TUESDAY THROUGH WEDNESDAY...VFR. CHC SHRA/ISO TSRA W/MVFR CIGS.
THURSDAY...VFR.
BEACHLER
&&
.MARINE...
320 AM CDT
THE MAIN MARINE FORECAST CONCERNS CONTINUE TO FOCUS ON WINDS
ASSOCIATED WITH THE REMNANTS OF TROPICAL DEPRESSION ISAAC...AS THE
LOW PRESSURE CENTER DRIFTS VERY SLOWLY FROM CENTRAL MISSOURI INTO
SOUTHERN ILLINOIS THROUGH EARLY SUNDAY...THEN SLOWLY WEAKENS OVER
THE OHIO VALLEY INTO MONDAY. EAST-NORTHEAST WINDS ACROSS THE
SOUTHERN PORTIONS OF LAKE MICHIGAN IN THE 15-20 KT RANGE...AND A
FEW GUSTS TO 25 KTS ESPECIALLY EARLY SUNDAY...WILL MAKE FOR
MARGINAL SMALL CRAFT ADVISORY CONDITIONS ALONG THE WESTERN SHORE
OF THE LAKE SUNDAY MORNING PARTICULARLY BETWEEN DOWNTOWN CHICAGO
AND THE WISCONSIN BORDER. HAVE DECIDED TO GO AHEAD AND HOIST A
SMALL CRAFT ADVISORY HEADLINE FOR THAT PORTION OF THE NEARSHORE
WATERS THROUGH SUNDAY.
OTHERWISE...AS THE LOW DRIFTS ACROSS SOUTHERN ILLINOIS AND THE
LOWER OHIO VALLEY AND WEAKENS SUNDAY NIGHT AND MONDAY...WEAK HIGH
PRESSURE RIDGING WILL LINGER ACROSS THE WESTERN GREAT LAKES AREA.
AN AREA OF LOW PRESSURE MOVING ACROSS CENTRAL SASKATCHEWAN AND
NORTHERN ONTARIO WILL TRAIL A COLD FRONT ACROSS LAKE MICHIGAN
TOWARD MID-WEEK.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH RIP CURRENT RISK...ILZ006-ILZ014...10 AM SATURDAY TO 7 PM
SUNDAY.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO NORTHERLY IS UNTIL 7 PM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
111 AM CDT SAT SEP 1 2012
.DISCUSSION...
349 PM CDT
MAIN FORECAST CONCERNS THIS FORECAST PERIOD REVOLVE AROUND PRECIP
CHANCES AND TRENDS...POSSIBLE HEAVY AT TIMES...THIS WEEKEND INTO
THE START OF NEXT WEEK AS REMNANTS OF TROPICAL STORM ISAAC WORK
ITS WAY NORTH ACROSS THE REGION.
IN THE NEAR TERM...LATEST SATELLITE IMAGERY DEPICTING EXPANSIVE
AREA OF MID AND HIGH LEVEL CLOUD COVER CONTINUING TO SPREAD
NORTHWARD ACROSS MUCH OF THE REGION AS THIS SYSTEM SLOWLY MOVES
NORTH. DESPITE AN INCREASE IN CLOUD COVER TODAY...MOSTLY SUNNY TO
PARTLY CLOUDY SKIES HAVE BEEN OBSERVED WITH TEMPERATURES RISING TO
THE LOWER 90S ACROSS NORTHERN ILLINOIS AND MID TO UPPER 80S ACROSS
AREAS SOUTH OF INTERSTATE 80. DESPITE LATEST RADAR IMAGERY SHOWING
SOME WEAK RETURNS FROM THE OUTER BANDS OF THIS SYSTEM ACROSS AREAS
FROM PONTIAC IN ILLINOIS EAST TO FOWLER IN INDIANA...MOST OF THIS
IS NOT REACHING THE GROUND. SOME DRIER AIR IS HELPING WITH THIS
BUT WITH A VERY MOIST AIRMASS ON ITS WAY...IT SHOULDNT TAKE MUCH
LONGER THIS EVENING BEFORE IT STARTS REACHING THE GROUND. OUTSIDE
OF THIS SYSTEM TO THE SOUTH...A COLD FRONT HAS BEEN DROPPING SOUTH
THROUGH PORTIONS OF WISCONSIN TODAY. ALTHOUGH...EXPECT THIS FRONT
TO LOSE ITS SOUTHWARD MOMENTUM THIS EVENING AND THEN BECOME MORE
DIFFUSE AS THE SYSTEM TO THE SOUTH MOVES INTO THE AREA. DESPITE
THIS FRONT ACROSS THE REGION...ANY VERTICAL DEVELOPMENT HAS BEEN
LIMITED AND IS EXPECTED TO REMAIN THIS WAY AS A MORE SUBSIDENT
LARGE SCALE ENVIRONMENT REMAINS OVER THIS BOUNDARY.
SHIFTING TOWARD MAIN FOCUS OF THIS FORECAST PERIOD...REMNANTS OF
TROPICAL STORM ISAAC CONTINUE TO SLOWLY SHIFT NORTH THROUGH
MISSOURI THIS AFTERNOON. THIS SYSTEM IS MARKED WITH A VERY MOIST
ENVIRONMENT...OR A TROPICAL ENVIRONMENT. COPIOUS AMOUNTS OF
MOISTURE WITH 12Z SOUNDINGS ACROSS MISSOURI INDICATING PWATS
AROUND 2.4 INCHES THIS MORNING...AND LATEST RUC ANALYSIS SHOWING
THIS AXIS OF HIGHER PWATS EXTENDING FROM THE ST. LOUIS AREA BACK
SOUTH THROUGH MISSOURI INTO ARKANSAS. WITH A SLOW MOVEMENT OF THIS
SYSTEM TONIGHT...THIS AXIS OF HIGHEST MOISTURE WILL ALSO SHIFT
SLOWLY. NONETHELESS...THESE OUTWARD BANDS OF THIS SYSTEM AND
HIGHER MOISTURE CONTENT AIR WILL LIFT NORTH OVERNIGHT. THIS SHOULD
HELP BRING SHOWERS ACROSS THE SOUTHERN CWA PRIMARILY FOR AREAS
ALONG AND SOUTH OF A LINE FROM PONTIAC IN ILLINOIS TO RENSSELAER
IN INDIANA. HEAVIER DOWNPOURS ARE NOT EXPECTED TONIGHT AS WELL AS
ANY THUNDER. DESPITE SOME INSTABILITY IN PLACE...THESE INITIAL
SHOWERS WILL BE WEAKLY FORCED. ITS NOT UNTIL SATURDAY THROUGH THE
REMAINDER OF THE WEEKEND THAT THE MAIN AXIS OF HIGHEST MOISTURE
AND RAINFALL WILL REACH THE CWA. WITH BETTER FORCING WITH THIS
SYSTEM SHIFTING NORTH AND SREF GUIDANCE INDICATING THAT THE AXIS
OF HIGHER PWATS/MUCH HIGHER DEWPOINT AIR WILL REACH THE SOUTHERN
CWA...THE POTENTIAL FOR HEAVIER RAIN WILL INCREASE. DESPITE SOME
MODEL VARIABILITY WITH THE OVERALL EVOLUTION OF THIS
SYSTEM...CONFIDENCE IS HIGH FOR AREAS ALONG AND SOUTH OF
INTERSTATE 80 TO RECEIVE THE HIGHEST AMOUNTS OF RAIN THIS WEEKEND.
WHERE CONFIDENCE IS LOWER AT THIS TIME IS IN REGARDS TO HOW FAR
NORTH THIS RAIN WILL WORK ITS WAY NORTH. AS A FAIRLY TIGHT
GRADIENT IS EXPECTED WITH THIS PRECIP SHIELD THIS WEEKEND...HAVE
TRIED TO CONVEY THIS AS BEST AS POSSIBLE IN THE GRIDS. IF THIS
SYSTEM WERE TO SHIFT NORTHWARD THAN PREVIOUSLY THOUGHT...THEN THIS
AXIS OF RAINFALL WOULD OF COURSE SHIFT NORTH ACROSS THE CWA. AT
THIS POINT IT APPEARS THAT A DRASTIC CUTOFF IN PRECIP SHOULD OCCUR
AROUND THE I88 CORRIDOR. IN ALL AREAS ACROSS OUR CWA ARE EXPECTED
TO RECEIVE A LARGE AMOUNT OF RAINFALL THROUGH SUNDAY NIGHT...WITH
THE POTENTIAL FOR AMOUNTS OF 4 TO 5 INCHES OR GREATER ALONG AND
SOUTH OF A LINE FROM THE PONTIAC AREA TO THE RENSSELAER AREA.
MOVING NORTH OF THIS LINE...RAINFALL AMOUNTS ARE EXPECTED TO TAPER
FROM AROUND 3 TO 4 INCHES TO AROUND 1 INCH JUST NORTH OF THE
INTERSTATE 80 CORRIDOR. EXPECTED AMOUNTS ALONG THE INTERSTATE 88
CORRIDOR WILL ROUGHLY RANGE FROM THREE QUARTERS OF AN INCH UP TO
ONE INCH...WITH THE POTENTIAL FOR LITTLE OR NO RAIN IN THE
COUNTIES BORDERING WISCONSIN...GENERALLY UNDER A QUARTER INCH. NO
HEADLINES AT THIS TIME BUT WILL CONTINUE THE ESF TODAY.
RODRIGUEZ
&&
.HYDROLOGY...
427 PM CDT
EXPECTED RAINFALL AND POTENTIAL FOR HEAVY RAINFALL...POTENTIALLY
FOR PERIODS OF TIME...ACROSS PORTIONS OF THE CWA STILL ON TRACK
LATE TONIGHT THROUGH THE END OF THE WEEKEND. LATEST OBSERVATIONAL
DATA STILL INDICATING A GOOD SWATH OF MOISTURE JUST SOUTH OF THE
CWA THIS AFTERNOON...WITH LATEST GUIDANCE INDICATING THIS HIGHER
MOISTURE CONTENT AIR TO CONTINUE SPREADING NORTHWARD TONIGHT INTO
SATURDAY. AS THIS SLUG OF MOISTURE MOVES ACROSS THE CWA EARLY
SATURDAY...IT WILL THEN LINGERING THROUGH THE REMAINDER OF THE
WEEKEND. ALTHOUGH...LATEST GUIDANCE CONTINUES TO INDICATE THAT THE
HIGHEST RAIN RATES/RAINFALL SHOULD STAY ACROSS THE SOUTHERN CWA
WHICH SEEMS TO BE ON TRACK. THE POTENTIAL FOR RAINFALL AMOUNTS OF
4 TO 5 INCHES OR GREATER ALONG AND SOUTH OF A LINE FROM THE
PONTIAC AREA TO THE RENSSELAER AREA SEEM TO BE ON TRACK FOR THIS
WEEKEND. MOVING NORTH OF THIS LINE...RAINFALL AMOUNTS ARE EXPECTED
TO TAPER FROM AROUND 3 TO 4 INCHES TO AROUND 1 INCH JUST NORTH OF
THE INTERSTATE 80 CORRIDOR. EXPECTED AMOUNTS ALONG THE INTERSTATE
88 CORRIDOR WILL ROUGHLY RANGE FROM THREE QUARTERS OF AN INCH UP
TO ONE INCH...WITH THE POTENTIAL FOR LITTLE OR NO RAIN IN THE
COUNTIES BORDERING WISCONSIN...GENERALLY UNDER A QUARTER INCH.
DESPITE THE EXPECTED HIGHER RAINFALL THIS WEEKEND...ONLY MINOR
RISES IN AREAS RIVERS ARE EXPECTED WITH NO MAJOR PROBLEMS EXPECTED
AT THIS TIME. A WORST CASE SCENARIO AT THIS TIME BASED ON CURRENT
FORECASTS WOULD BE FOR RIVERS THAT RECEIVE THESE HIGHER AMOUNTS TO
RISE TO MINOR OR JUST ABOVE MODERATE STAGES. ALTHOUGH WOULD LIKE
TO REITERATE SOME UNCERTAINTY WITH THIS SYSTEMS OVERALL
EVOLUTION...THAT EXTENDS INTO THE POTENTIAL RISES. WITH THIS IN
MIND...THIS SITUATION NEEDS TO CONTINUE TO BE CLOSELY MONITORED
THIS WEEKEND AS IT WOULD NOT BE OUT OF THE QUESTION FOR LOCALIZED
AREAS OF HIGHER AMOUNTS AND THUS POSSIBLE HIGHER RISES. SOMETHING
ELSE TO KEEP IN MIND THIS WEEKEND IS THE OVERALL SOIL CONDITIONS
ACROSS THE AREA. WITH A DRY/HARD SOIL IN PLACE...IT WOULD NOT TAKE
MUCH TIME FOR HIGH RAINFALL RATES TO QUICKLY TURN INTO RUNOFF.
ONCE AGAIN...HAVE NOT ISSUED ANY FLOOD HEADLINES AT THIS TIME.
ALTHOUGH...CONTINUE TO MONITOR LATEST UPDATES THIS WEEKEND AS THIS
COMPLEX SYSTEM UNFOLDS ACROSS THE REGION.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* NORTHEAST WINDS WITH GUSTS ABOVE 15 KTS TODAY BECOMING MORE
EASTERLY TONIGHT.
* TIMING OF RAIN AFFECTING TODAY/TONIGHT.
* POTENTIAL FOR MVFR CIG/VIS IF RAIN PERSISTS.
RATZER
//DISCUSSION...UPDATED 06Z...
TROPICAL DEPRESSION ISAAC WAS LOCATED OVER WEST CENTRAL MISSOURI
AT 05Z...WITH AN AREA OF MODERATE RAIN EXTENDING FROM FAR EASTERN
KANSAS ACROSS NORTHERN MISSOURI INTO MUCH OF CENTRAL/SOUTHERN IL.
ISAAC IS EXPECTED TO DRIFT VERY SLOWLY EAST INTO SOUTHERN IL
THROUGH SUNDAY MORNING. MAIN FORECAST QUESTION FOR THE TAFS IS
WHERE THE NORTHERN PERIPHERY OF THE RAIN ASSOCIATED WITH THIS
SYSTEM LAYS OUT IN RELATION TO THE TERMINAL LOCATIONS...AND THE
POTENTIAL FOR MVFR OR EVEN IFR CIG/VIS CONDITIONS IN THE AREAS
WHICH SEE PERSISTENT RAINFALL. 00Z HIGH RESOLUTION MODEL GUIDANCE
SUGGESTS THAT THE NORTHERN EDGE OF THE RAIN AREA WILL BE
APPROXIMATELY THROUGH THE INTERSTATE 88 CORRIDOR ACROSS NORTHERN
IL WITH AREAS TO THE NORTH LESS LIKELY TO SEE PERSISTENT RAIN AND
ASSOCIATED CIG/VIS REDUCTIONS. THIS MAKES FOR A TRICKY FORECAST
WITH TERMINALS IN/NEAR THE EXPECTED SHARP GRADIENT OF LITTLE/NO
RAIN TO THE NORTH AND CONSIDERABLE RAIN FARTHER TO THE SOUTH.
RFD WILL HAVE THE LOWEST LIKELIHOOD OF SEEING ANY PROLONGED PERIOD
OF RAIN AND LOWER CIG/VIS...WITH AN EXPECTATION THAT ORD/DPA WILL
PERHAPS SEE A FEW PERIODS OF LIGHTER RAIN AND GYY FARTHEST TO THE
SOUTH WOULD HAVE THE GREATEST THREAT OF LONGER DURATION RA/SHRA
AND ALSO LOWER CIG/VIS CONDITIONS. FOR NORTHERN TERMINALS...THE
GREATEST POTENTIAL FOR SOME RAIN TO AFFECT RFD/DPA/ORD/MDW WOULD
BE DURING THE AFTERNOON HOURS AS LOW/MID LEVEL MOISTURE CONVERGENCE
EXPANDS NORTHEASTWARD PER MODELS. HIGH-RES GUIDANCE INDICATES SOME
SHOWERS MAY AFFECT GYY AS EARLY AS THIS MORNING...WITH SOME WEAK
RADAR ECHOES ALREADY DEVELOPING SOUTH OF THE KANKAKEE RIVER VALLY
INTO INDIANA.
WINDS ARE EXPECTED TO REMAIN EAST-NORTHEAST THROUGH THE PERIOD AS
THE SURFACE LOW PRESSURE CIRCULATION MOVES SLOWLY ACROSS MISSOURI
AND DOWNSTATE IL. SOME GUSTS INTO THE 15-20 KT RANGE APPEAR
POSSIBLE MAINLY DURING THE DAY TODAY...THOUGH WEAK LOW LEVEL LAPSE
RATES SUGGEST GUSTS MAY BE SOMEWHAT SPORADIC.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN WIND TRENDS. MEDIUM CONFIDENCE GUST SPEEDS.
* MEDIUM CONFIDENCE IN RAIN POTENTIAL AND CIG/VIS TRENDS.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...OCCASIONAL RA. MVFR PSBL IFR CIGS.
MONDAY...CHC RA ISO TSRA. MVFR PSBL.
TUESDAY THROUGH WEDNESDAY...VFR. CHC SHRA/ISO TSRA W/MVFR CIGS.
THURSDAY...VFR.
BEACHLER
&&
.MARINE...
351 PM CDT
A COLD FRONT IS SLOWLY SINKING SOUTH ALONG LAKE MICHIGAN AND IS
CURRENTLY LOCATED FROM THE WI/IL STATE LINE THROUGH MUSKEGON. THE
FRONT WILL REACH SOUTHERN LAKE MICHIGAN THIS EVENING WITH WINDS
TURNING NORTH TO NORTHEAST AND GUSTING TO AROUND 20 KT. WINDS WILL
DIMINISH TO 10 TO 15 KT BEHIND THE FRONT AND VEER TO THE EAST BY
SATURDAY MORNING OVER THE SOUTHERN HALF OF THE LAKE. WINDS WILL BE
EAST ALONG THE ENTIRE LAKE BY SATURDAY NIGHT. THE PERSISTENT
EASTERLY FLOW WILL RESULT IN LOCALLY HIGHER WAVES ALONG THE SOUTHERN
WI AND IL COAST LINE OF 5 TO 8 FT BY SUNDAY AFTERNOON. WAVES IN THE
IL NEARSHORE ZONES LOOK LIKE THEY WILL STAY JUST BELOW SMALL CRAFT
ADVISORY CRITERIA...THEREFORE WILL REFRAIN FROM ISSUING A SCY NOW.
HOWEVER...THE HIGHER WAVES AND ONSHORE FLOW ALONG THE IL NEARSHORE
ZONES DO POSE AN INCREASED RIP CURRENT RISK. THE RISK ALSO IS
INCREASED BY THE FACT THERE WILL PROBABLY BE AN ABOVE AVERAGE NUMBER
OF SWIMMERS AT THE BEACH THIS HOLIDAY WEEKEND. ISSUED A RIP CURRENT
STATEMENT FOR THE IL SIDE OF THE LAKE SATURDAY MORNING THROUGH
SUNDAY EVENING.
HIGH PRESSURE SPREADS ACROSS THE WESTERN GREAT LAKES TONIGHT.
MEANWHILE LOW PRESSURE THAT WAS FORMALLY HURRICANE ISAAC IS MOVING
NORTHWARD. THE PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS WILL
TIGHTEN OVER SOUTHERN LAKE MICHIGAN. THEREFORE EAST WINDS WILL BE
STRONGER OVER THE SOUTHERN HALF OF THE LAKE. THE LOW WILL ENTER
SOUTH CENTRAL IL LATE SATURDAY AFTERNOON AND THEN TURN EASTWARD
PASSING SOUTH OF LAKE MICHIGAN. HIGH PRESSURE MOVES OVER THE LAKE
MONDAY NIGHT WITH WINDS WEAKENING ACROSS THE LAKE. ANOTHER TROUGH OF
LOW PRESSURE APPROACHES FROM THE WEST MID NEXT WEEK BUT CONFIDENCE
IS LOW ON THE EXACT TIMING OF THIS SYSTEM DUE TO GUIDANCE
INCONSISTENCIES.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH RIP CURRENT RISK...ILZ006-ILZ014...10 AM SATURDAY TO 7 PM
SUNDAY.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
934 PM EDT SUN SEP 2 2012
.SYNOPSIS...
A STATIONARY FRONT WILL PERSIST OVER THE CENTRAL MID ATLANTIC
OVERNIGHT...THEN LIFT NORTH AS A WARM FRONT ON MONDAY.
MEANWHILE...REMNANTS OF ISAAC WILL CONTINUE DRIFTING EAST FROM THE
MIDWEST THROUGH TUESDAY NIGHT. AN UPPER TROUGH LOOKS TO CONTINUE
THE ACTIVE WEATHER PERIOD INTO THURSDAY BEFORE A COLD FRONT
CROSSES THE REGION LATE THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A STRONG H5 VORT FROM THE DECAYING PREDECESSOR RAINFALL EVENT
FROM THE REMNANTS OF ISAAC IS MOVING THROUGH THE REGION NOW
THROUGH OVERNIGHT. THIS WAS THE LIFTING MECHANSIM THAT PRODUCED THIS
EVENINGS SHOWERS AND ISLTD TSTMS. EXPECT THIS ACTIVITY TO LIFT A
BIT NORTH OVERNIGHT AND CONTINUE THROUGH 2 AM WHEN THE VORT MAX
WILL BE OVER THE CHESAPEAKE BAY. RAP MODEL SHOWS INCREASING
STABILITY OVERNIGHT SO DO NOT ANTICIPATE ANY SEVERE WEATHER.
PATCHY FOG AND LOW CIGS OVERNIGHT AS INVERSION DEVELOPS WITH LOW
LCLS.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
BEST CHANCE FOR WIDESPREAD FLASH FLOODING APPEARS TO BE DELAYED
UNTIL TUE NIGHT INTO WED. WE WILL SEE LOCALIZED FLASH FLOODING
AGAIN ON MONDAY LABOR DAY...PROBABLY A FEW MORE EVENTS THAN WE SAW
TODAY IN CHARLES COUNTY...ST MARYS COUNTY...AND DC.
WIDESPREAD PRECIP IS EXPECTED TO DEVELOP ONCE AGAIN ACROSS THE CWFA
DURING THE DAY ON MONDAY. KEPT THE LIKELY POPS IN PLACE. LOCALIZED
FLASH FLOODING IS POSSIBLE OVERNIGHT AND TOMORROW AS THE SOILS
CONTINUE TO SATURATE.
THE REMNANTS OF ISAAC ARE EXPECTED TO CONTINUE AFFECTING THE MID
ATLANTIC INTO WEDNESDAY...CONTINUING PERIODIC HEAVY SHOWERS AND
THUNDERSTORMS. FLASH FLOODING IS POSSIBLE THROUGH THE SHORT TERM.
MONDAY NIGHT THROUGH TUESDAY NIGHT...REMNANTS OF ISAAC TRACK UP THE
OHIO VALLEY...WITH THE WARM FRONT AHEAD OF THIS LOW PERSISTING
AROUND THE MASON-DIXON LINE. LIKELY POPS SPREAD EAST THROUGH THIS
TIMEFRAME. PWATS WILL REMAIN AROUND 2.2 INCHES THROUGH THIS
TIME...SO HEAVY RAINFALL IS LIKELY AND A FLASH FLOOD THREAT WILL
ALSO REMAIN. TEMPERATURES A FEW DEGREES ABOVE NORMAL WILL PERSIST
FROM SLY SFC FLOW UNDER THICK CLOUDS.
WEDNESDAY...WEAK COLD FRONT IN THE WAKE OF THE EXTRA-TROPICAL ISAAC
REMNANTS CONTINUES LIKELY POPS...WITH PRECIP TAPERING OFF BEHIND THE
FRONT. HOWEVER...THIS REALLY IS NOT MUCH OF A COLD FRONT AS 16C 850
TEMPS BUILD IN BEHIND THE SYSTEM. IN FACT A WARMING TREND IS
EXPECTED FOR LATER IN THE WEEK...OWING MOSTLY TO INCREASED SUNSHINE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
UPR TROUGH IN WAKE OF ISAAC REMNANTS CROSSES THE REGION THURSDAY.
WENT WITH CHANCE POPS FOR NOW...THOUGH CONSIDERING HOW
PRECONDITIONED THE SOIL WILL BE LIKELIES WILL PROBABLY BE ABLE TO BE
PUT IN SOON.
IN A LOOK AHEAD TO NEXT WEEKEND...HIGH PRESSURE IN THE WAKE OF THE
UPR TROUGH FRIDAY LOOKS TO BE SHORT LIVED AS A DEEPER TROUGH IS
PROGGED TO APPROACH THE MID ATLANTIC SATURDAY NIGHT/SUNDAY.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
A STATIONARY FRONT WILL REMAIN STATIONARY ACROSS NORTH CENTRAL
VIRGINIA OVERNIGHT...BUT BEGIN SHIFTING NORTHWARD ON MONDAY.
CIGS AOB 040 WILL PERSIST OVERNIGHT FOR MOST OF THE TERMINALS. PRECIP WILL
BECOME MORE WIDESPREAD DURING THE LATE MORNING AND EARLY AFTERNOON
HOURS ON MONDAY. SUB VFR VSBYS AT MOST TERMINAL SITES OVERNIGHT WITH
SHRA/TSRA AND AGAIN TOMORROW AFTERNOON.
ONGOING PRECIPITATION EVENT FROM THE REMNANTS OF ISAAC CONTINUES
MONDAY NIGHT THROUGH WEDNESDAY. SFC FLOW WILL MAINLY BE SLY WITH
MVFR/IFR CONDS EXPECTED IN THE SHRA/TSRA. MORE ACTIVE WEATHER
THURSDAY BEFORE BRIEF HIGH PRESSURE THEN INTO NEXT WEEKEND.
&&
.MARINE...
EAST/SOUTHEAST FLOW AOB 15 KT WILL CONTINUE ACROSS THE WATERS
THROUGH TOMORROW. NO HEADLINES ANTICIPATED...BUT A FEW SPECIAL
MARINE WARNINGS ARE POSSIBLE WITH GUSTY THUNDERSTORMS THROUGH THIS
EVENING.
A STATIONARY FRONT WILL REMAIN ACROSS THE BAY OVERNIGHT BUT
BEGIN SHIFTING NORTHWARD DURING THE DAY TOMORROW.
SELY FLOW CONTINUES THROUGH TUESDAY NIGHT AS REMNANTS OF ISAAC
APPROACH FROM THE WEST. FLOW BECOMES SLY TUESDAY NIGHT AND CONTINUES
THROUGH MIDWEEK AS THE REMNANTS TRACK TO THE NORTH OF THE CHESAPEAKE
BAY. HEAVY SHOWERS AND THUNDERSTORMS PERSIST ACROSS THE WATERS
THROUGH WEDNESDAY.
&&
.TIDES/COASTAL FLOODING...
CONTINUED EASTERLY FLOW INCREASES SHOULD CAUSE MINOR FLOODING FOR
THE MONDAY HIGH TIDES. THE COASTAL FLOOD THREAT CONTINUES THROUGH
WEDNESDAY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BAJ/LEE/NWL
NEAR TERM...LEE
SHORT TERM...BAJ/NWL
LONG TERM...BAJ
AVIATION...BAJ/LEE/NWL
MARINE...BAJ/LEE/NWL
TIDES/COASTAL FLOODING...LEE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
409 PM EDT SAT SEP 1 2012
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 407 PM EDT SAT SEP 1 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF OVER THE PACIFIC NW
WITH DOWNSTREAM RIDGE EXTENDING N INTO SCNTRL CANADA. REMNANT OF
ISAAC IS OVER THE MID MISSISSIPPI VALLEY. DOWNSTREAM OF THE RIDGE
AXIS AND WELL N OF ISAAC REMNANT...TRANQUIL WEATHER DOMINATES UPPER
MI THIS AFTN UNDER ABUNDANT SUNSHINE. THE TRANQUIL WEATHER WILL
PERSIST THRU THE SHORT TERM AS THE UPSTREAM RIDGE SHIFTS E...
REACHING THE GREAT LAKES SUN.
AS SFC HIGH OVER LAKE SUPERIOR DRIFTS E TONIGHT...LIGHT RETURN FLOW
WILL GET UNDERWAY...ESPECIALLY W. SHOULD STILL BE A GOOD RADIATIONAL
COOLING NIGHT UNDER MAINLY CLEAR SKIES...THOUGH NOT AS GOOD AS LAST
NIGHT DUE TO DEVELOPING LIGHT RETURN FLOW AND INCREASING COLUMN
MOISTURE. FAVORED THE LOW SIDE OF AVBL GUIDANCE WHICH HAS
TRADITIONAL COLD SPOTS DROPPING TO THE LWR 40S. THERE IS SOME
CONCERN THAT DEVELOPING LOW-LEVEL E TO SE FLOW ACROSS NRN LAKE MI
COULD LEAD TO STRATUS/FOG DEVELOPMENT OVER THE SCNTRL FCST AREA AS
MARINE MODIFIED HIGHER DWPTS ADVECT INLAND/UPSLOPE INTO THE
RADIATIONALLY COOLED BOUNDARY LAYER INLAND. AT THIS TIME...IT
APPEARS SFC WINDS WILL BE BACKED ENOUGH OVER SCNTRL UPPER MI TO
PREVENT MUCH INLAND ADVECTION OF MOISTURE. WILL BE SOMETHING TO
MONITOR OVERNIGHT.
DRY AIR MASS WILL LINGER THRU SUN AFTN...PROVIDING ONE MORE DRY/WARM
EARLY SEPT DAY. PER FCST SOUNDINGS...STRENGTHENING CAP SUN WILL
LIMIT MIXING DEPTH COMPARED TO RECENT DAYS. MIXING TO 850MB YIELDS
MAX TEMPS MOSTLY IN THE LWR 80S AWAY FROM LAKE MODERATION. ALTHOUGH
VERY DRY AIR LINGERS ALOFT (CENTERED AROUND 800MB)...SFC DWPTS
SHOULDN`T FALL AS MUCH AS IN RECENT AFTNS SINCE MIXING WON`T TAP AS
SIGNIFICANTLY INTO THE DRIER ALOFT. STILL...WITH DWPTS FALLING
TOWARD 50F IN THE AFTN...RH WILL BOTTOM OUT AS LOW AS 30-35PCT.
ALTHOUGH PRES GRADIENT WILL BEGIN TO TIGHTEN BTWN DEPARTING SFC HIGH
AND APPROACHING COLD FRONT OVER THE PLAINS...SFC RIDGING EXTENDING
BACK TO UPPER MI WILL HELP TO SLOW THE INCREASE IN WINDS...AND THIS
WILL HELP TO EASE FIRE WX CONCERNS SUN.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 407 PM EDT SAT SEP 1 2012
MUCH OF OUR WEATHER FOR THIS LONG TERM PERIOD WILL BE HEAVILY
INFLUENCED BY THE 500MB LOW CURRENTLY SPINNING ALONG THE BRITISH
COLUMBIA/ALBERTA BORDER...WHICH WILL SET UP HOUSE OVER
ONTARIO/HUDSON BAY/QUEBEC FROM WEDNESDAY THROUGH AT LEAST NEXT
SATURDAY.
SUNDAY NIGHT...
WILL BEGIN SUNDAY NIGHT WITH THE WRAPPED UP SFC LOW SET UP ACROSS N
SASKATCHEWAN...WITH THE COLD FRONT/OCCLUDED FRONT PUSHING SSE
THROUGH C MANITOBA AND DOWN THROUGH THE RED RIVER VALLEY OF THE N.
LIGHT S WINDS WILL BE COMMON...KEEPING TEMPS FROM FALLING INTO THE
LOW 50S...WITH THE WARMEST TEMPS IN THE 60S NEAR THE GREAT LAKES.
MONDAY...
TIMING OF THE COLD FRONT HAS SLOWED DOWN A BIT...NO LONGER OVER W
LAKE SUPERIOR BY 12Z MONDAY...BUT JUST W. THE LOW ITSELF WILL ONLY
BE ABLE TO PUSH TO W CENTRAL MANITOBA WHERE IT WILL BECOME NEARLY
STATIONARY...SLOWLY EDGING TO NE MANITOBA BY 00Z WEDNESDAY.
MEANWHILE ACROSS UPPER MICHIGAN...UNIDIRECTIONAL WINDS AND AFTERNOON
HEATING COMBINED WITH THE WEAKENING COLD FRONT WILL ALLOW FOR SHOWER
AND THUNDERSTORM DEVELOPMENT. THE MAIN THREAT WILL BE STRONG GUSTY
WINDS DURING THE AFTERNOON...AND EARLY EVENING HOURS FAR E. MUCH OF
THE AREA IS IN A SPC SLIGHT RISK AREA FOR DAY 3/MONDAY. ADDED THE
POTENTIAL TO THE HWO...BUT IT LOOKS MODERATE AT THIS TIME...GIVEN
0-6KM BULK SHEAR VALUES AOB 35KTS...WITH HIGHER VALUES REMAINING W
AND S OF THE CWA. WHILE THE OUTPUT FROM THE 12Z GFS IS NOT AS
EXCITED ABOUT THE POTENTIAL...THE NAM DOES HAVE 0-3KM SHR VALUES OF
150-200M2/S2 OVER FAR W UPPER MI BY 18Z...AND OVER MUCH OF W UPPER
MI BY 21Z. THE BRUNT OF THE STORMS/PRECIP SHOULD BE TRACKING E
15-20KTS.
TUESDAY THROUGH WEDNESDAY...
WARMED UP HIGH TEMPS FOR TUESDAY ROUGHLY 5 DEGREES...WITH THE
HIGHEST VALUES S CENTRAL AND E. THIS AREA SHOULD HAVE THE LEAST
CHANCE OF SEEING PRECIP AND LIGHT SSW WINDS. ANOTHER SURGE OF COOLER
AIR WILL BE TO OUR W...WITH THE SECONDARY COLD FRONT SET UP OVER MN
TUESDAY AFTERNOON. IT SHOULD MOVE ACROSS W UPPER MI TUESDAY EVENING.
SPED UP THE EXIT OF TS IN THE GRIDS FOR WEDNESDAY.
THURSDAY THROUGH SATURDAY...
COOL NW FLOW WITH 850MB TEMPS FALLING TO 6-9C...ASSISTED ADDITIONAL
WEAK SHORTWAVES ALOFT...WILL LIKELY RESULT IN SPRINKLES/DRIZZLE
ACROSS THE FAVORED UPSLOPE LOCATIONS NEAR LAKE SUPERIOR AND E. THESE
LOW POP/LOW QFP SHOWERS WILL CONTINUE OFF AND OFF THROUGH FRIDAY AS
850MB TEMPS COOL A COUPLE MORE DEGREES...AND THE MAIN 500MB TROUGH
SINKS ACROSS THE CWA. MODEL GUIDANCE IS IN FAIRLY GOOD SHAPE...WRT
THE 12Z ISSUANCES...THROUGH FRIDAY MORNING. AFTER THAT TIME THE 12Z
GFS EJECTS THE MAIN 500MB LOW THAT HAD BEEN SITTING NEAR JAMES BAY
AT 12Z FRIDAY QUICKLY NORTHEASTWARD. THE ECMWF ON THE OTHER HAND
JUST HAS THE LOW SLOWLY SINK SE TO QUEBEC. EVEN SO...HIGH PRESSURE
SHOULD STILL BE ABLE TO PUSH ACROSS THE UPPER GREAT LAKES
SATURDAY...THE GFS IS JUST A BIT QUICKER. LAKE BREEZES DOMINATING AT
LEAST LAKE MI BY THE EARLY AFTERNOON HOURS. W FLOW MAY BE MORE
STEADY N ACROSS LAKE SUPERIOR.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 134 PM EDT SAT SEP 1 2012
VFR CONDITIONS WILL CONTINUE AT KIWD/KCMX/KSAW THRU SUNDAY AS DRY
HIGH PRESSURE REMAINS OVER/NEAR THE UPPER GREAT LAKES.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 407 PM EDT SAT SEP 1 2012
UNDER SFC HIGH PRES...WINDS ACROSS LAKE SUPERIOR WILL REMAIN LIGHT
TONIGHT...MOSTLY UNDER 15KT. AS THE HIGH SHIFTS TO THE E SUN...E TO
SE WINDS WILL BEGIN TO INCREASE...REACHING UP TO 20KT OVER FAR WRN
LAKE SUPERIOR AND PORTIONS OF CNTRL LAKE SUPERIOR IN THE AFTN. AS A
COLD FRONT APPROACHES SUN NIGHT...SOUTHERLY WINDS MAY GUST AS HIGH
AS 25KT AT HIGHER OBS PLATFORMS...ESPECIALLY OVER THE E HALF OF THE
LAKE. PRES GRADIENT THEN SLACKENS WITH PASSING COLD FRONT MON...
RESULTING IN WINDS DIMINISHING BACK TO UNDER 15KT MON INTO TUE. NEXT
COLD FRONT PASSING WED WILL BRING AN INCREASE IN W TO NW WINDS TO
AROUND 20KT...MAYBE HIGHER...LATER WED INTO THU.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...KF
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
123 AM EDT SAT SEP 1 2012
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 401 PM EDT FRI AUG 31 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF OVER THE PACIFIC
NW...RIDGING DOWNSTREAM OVER THE NRN PLAINS/SCNTRL CANADA AND A TROF
OVER SE CANADA/NEW ENGLAND. THE UPSTREAM RIDGE IS CURRENTLY GAINING
AMPLITUDE. WITH THE RIDGE CONTINUING TO BUILD THRU SAT AS IT SHIFTS
E TOWARD THE UPPER LAKES...THE SHORT TERM PORTION OF THE FCST WILL
BE TRANQUIL. THERE IS AN AREA OF MID/HIGH CLOUDS OVER THE DAKOTAS...
AND THE CLOUDS HAVE SOME SUPPORT FROM THE RIGHT ENTRANCE OF UPPER
JET ALONG THE U.S./CANADA BORDER THRU THE UPPER LAKES. SINCE THE
UPPER JET SUPPORT BREAKS DOWN TONIGHT...CLOUDS SHOULD TEND TO
DISSIPATE AND PROBABLY WON`T BE MUCH OF A FACTOR HERE. UNDER MAINLY
CLR SKIES...WINDS WILL DROP OFF TO CALM/NEAR CALM AS SFC HIGH PRES
OVER NW MN SETTLES OVER THE UPPER GREAT LAKES TONIGHT. COMBINED
WITH A DRY COLUMN (PRECIPITABLE WATER 50-60PCT OF NORMAL)...TONIGHT
WILL BE A STRONG RADIATIONAL COOLING NIGHT. OPTED TO GO AT OR BLO
THE LOWEST GUIDANCE OVER THE INTERIOR...ESPECIALLY THE W SINCE
WINDS THERE WILL FALL TO CALM AROUND SUNSET. EXPECT MINS AS LOW AS
THE UPPER 30S IN THE TRADITIONAL COLD SPOTS. DIMINISHING SOIL
MOISTURE DUE TO RECENT DRY SPELL WILL ALSO AID COOLING POTENTIAL
TONIGHT. TYPICAL FOR THIS TIME OF YEAR...LENGTHENING NIGHTS AND WARM
WATER IN SWAMPS/STREAMS/RIVERS/LAKES MAY LEAD TO SOME GROUND FOG.
UNDER MOSTLY SUNNY SKIES...THE FIRST DAY OF METEOROLOGICAL AUTUMN
WILL BE A NICE ONE. ALTHOUGH TEMPS WILL BE ABOVE NORMAL...LOW DWPTS
WILL MAKE FOR A COMFORTABLE DAY. MIXING TOWARD 800MB ON FCST
SOUNDINGS YIELDS MAX TEMPS AROUND 80F INTO THE LWR 80S IN THE
INTERIOR. WITH SFC HIGH SETTING UP OVER LAKE SUPERIOR...LAKESIDE
LOCATIONS WILL HOLD TO THE LOW/MID 70S. WEAKER LAKE BREEZE OFF LAKE
MI WILL PROVIDE LIMITED COOLING. AFTN DWPTS WILL LIKELY FALL TOWARD
THE LWR 40S IN THE INTERIOR BASED ON MIXING DEPTH. ALTHOUGH RH WILL
BOTTOM OUT AS LOW AS THE 25-30PCT RANGE...LIGHT WINDS WILL HELP TO
EASE FIRE WX CONCERNS.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 401 PM EDT FRI AUG 31 2012
SATURDAY NIGHT...
THE APEX OF THE SFC TO 500MB RIDGE WILL BE NEAR THE CWA AT 00Z
SUNDAY...WITH THE REMNANTS OF ISAAC ACROSS MO. LOOK FOR THE SFC HIGH
TO SHIFT E TO THE ONTARIO/QUEBEC BORDER AND LOWER GREAT LAKES
OVERNIGHT...WITH A WEAK RETURN OF SSE FLOW WITH SOME MOISTENING OF
THE ATMOSPHERE THANKS TO WINDS PUSHING N AROUND WHAT IS LEFT OF
ISAAC. PW VALUES STARTING OFF AROUND 0.5IN EAST /55 PERCENT OF
NORMAL/ JUMPING TO VALUES RIGHT AROUND NORMAL FOR THIS TIME OF YEAR
BY 12Z SUNDAY...OR 0.75 TO 1IN.
SUNDAY THROUGH SUNDAY NIGHT...
SLIGHT SW FLOW BEGINS ALOFT BEGINS SUNDAY...AND BECOMES MORE ZONAL
MONDAY AS THE 500MB LOW TRANSITIONING ACROSS CENTRAL/S CANADA PUSHES
ACROSS SASKATCHEWAN AND MANITOBA. THERE ARE SIGNIFICANT
DISCREPANCIES WRT THE 31/06Z GFS AND 31/00Z ECMWF...WITH THE 31/00Z
CANADIAN LOOKING TO BE A CLOSE BLEND OF THE 2. THE 12Z RUNS OF THE
GFS AND ECMWF ARE MOVING CLOSER TO A SIMILAR SOLUTION WITH THE
CANADIAN TRACKING LOW. THE RESULT WILL BE AN INCREASE IN
MOISTURE...WITH THE SFC LOW OVER N SASKATCHEWAN AT 18Z SUNDAY...AND
THE COLD FRONT EXTENDING THROUGH THE DAKOTAS AND CENTRAL PLAINS.
EXPECT INCREASED S WINDS SUNDAY NIGHT IN ADVANCE OF THE COLD
FRONT...WITH A CHANCE OF TSRA WEST BY DAYBREAK MONDAY.
MONDAY THROUGH TUESDAY...
THE SFC COLD FRONT SET UP OVER FAR W LAKE SUPERIOR AT 12Z MONDAY /OR
EVEN ACROSS THE KEWEENAW PENINUSLA ACCORDING TO THE 31/00Z
ECMWF/...WILL PUSH JUST E OR RIGHT ACROSS THE FAR E END OF THE CWA
BY 00Z TUESDAY. SO FOR MEMORIAL DAY...A CHANCE OF TSRA WILL CONTINUE
TO TRACK E...WITH IMPROVING CONDITIONS W BY EARLY AFTERNOON. I
ATTEMPTED TO KEEP THE BEST CHANCE OF THUNDER RIGHT ALONG AND JUST
AHEAD OF THE FRONT. MONDAY NIGHT STILL LOOKS TO BE MAINLY DRY AS
HIGH PRESSURE PUSHES IN FROM THE SSW...AS TEMPS FALL INTO THE MID
50S INTERIOR W.
TUESDAY NIGHT THROUGH FRIDAY...
UNSETTLED WEATHER AND A RETURN TO NEAR NORMAL TEMPS WILL LIKELY BE
THE NORM FROM TUESDAY NIGHT THROUGH FRIDAY AS A SERIES OF
DISTURBANCES PUSH OVER OR JUST NORTH OF THE CWA. GIVEN THE FCST
DISCREPANCIES FROM THE VARIOUS MODELS...WILL NOT BE TERRIBLY
SPECIFIC WITH TIMING AS LOW PRESSURE SYSTEMS PUSH NEAR OR JUST N OF
LAKE SUPERIOR.
WINDS WEDNESDAY WILL LIKELY BE HIGHER THAN FORECAST. THE MAIN
DILEMMA HERE STEMS FROM AN AVERAGING OF MODEL GUIDANCE
DIRECTIONS...NW OFF THE GFS AND S OFF THE ECMWF. THE 12Z RUNS GIVE
GETTER CONFIDENCE IN A MORE NW FLOW SOLUTION...SIMILAR TO THE 06Z
RUN OF THE GFS. THIS WILL NEED TO BE LOOKED AT A BIT CLOSER OVER THE
NEXT COUPLE OF RUNS...TO MAKE SURE THIS TREND CONTINUES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 122 AM EDT SAT SEP 1 2012
VFR CONDITIONS ARE EXPECTED AS DRY HIGH PRESSURE REMAINS IN CONTROL
THROUGH MUCH OF THE WEEKEND.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 401 PM EDT FRI AUG 31 2012
AS SFC HIGH PRES SETTLES OVER LAKE SUPERIOR TONIGHT AND SAT...WINDS
WILL MOSTLY BE UNDER 15KT. AS THE HIGH SHIFTS TO THE E SAT NIGHT/SUN
AND A COLD FRONT APPROACHES FROM THE W...SOUTHEASTERLY WINDS WILL
GRADUALLY INCREASE...REACHING 10-20KT. SOUTHERLY WINDS MAY GUST UP
TO AROUND 25KT SUN NIGHT/EARLY MON JUST AHEAD OF THE FRONT. THE
STRONGER WINDS WILL BE OBSERVED ON THE HIGHER OBS PLATFORMS. PRES
GRADIENT THEN SLACKENS WITH PASSING COLD FRONT MON...RESULTING IN
WINDS DIMINISHING BACK TO UNDER 15KT MON INTO TUE. THE LIGHTER WINDS
WILL THEN PERSIST INTO WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...KF
AVIATION...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
351 PM CDT SAT SEP 1 2012
.SHORT TERM...
ISSUED AT 347 PM CDT SAT SEP 1 2012
(TONIGHT AND SUNDAY)
MAIN CONCERN CONTINUES TO BE SEVERE POTENTIAL AND LOCALLY HEAVY
RAINFALL. THIN LINE OF STORMS EXTENDING FROM CENTRAL ILLINOIS
SOUTHWESTWARD INTO SOUTHEAST MISSOURI WILL CONTINUE TO MOVE NORTH
NORTHEAST THE NEXT FEW HOURS. THE RAP IS SHOWING PERSISTENT LOW
LEVEL MOISTURE CONVERGENCE AS A VORT MAX MOVES AROUND THE SOUTH SIDE
OF THE UPPER LOW NOW MEANDERING OVER MISSOURI. OBJECTIVE ANALYSIS
OVER THIS SAME AREA DEPICTS SBCAPES 1000-1500 J/KG WHICH SHOULD
DIMINISH THROUGH THE EVENING. LIKE YESTERDAY...THERE IS LITTLE DEEP
LAYER SHEAR WITH THIS SYSTEM...SO ANY SEVERE WEATHER WILL BE SHORT
LIVED. MAIN CONCERN IS WHERE THE TORNADO WATCH IS IN EFFECT FOR
SHORT LIVED TORNADOES WHERE 0-1KM SRH VALUES ARE CURRENTLY IN THE
200-250 J/KG RANGE.
SEVERE THREAT WILL WANE THROUGH THE EVENING AS THE INSTABILITY
WEAKENS. WILL CONTINUE TO SEE AREAS OF RAIN THIS EVENING INTO THE
OVERNIGHT. WILL BEGIN TO SLOWLY LOWER POPS FROM WEST TO EAST
TONIGHT AS THE UPPER LOW MOVES EAST. THERE MAY BE SOME LOCALLY
HEAVY RAINFALL WITH THE THUNDERSTORMS INTO EARLY EVENING THAT
COULD CAUSE SOME LOCALIZED FLOODING ALONG AREA CREEKS AND LOW
LYING AREAS. ADDITIONAL RAINFALL TOTALS WILL RANGE FROM A COUPLE
OF TENTHS OVER CENTRAL MISSOURI TO OVER AN INCH OVER SOUTH CENTRAL
ILLINOIS.
BRITT
&&
.LONG TERM...
ISSUED AT 347 PM CDT SAT SEP 1 2012
(SUNDAY NIGHT THROUGH NEXT SATURDAY)
FOLLOWED THE GFS WHICH HAS THE UPPER LOW CONTINUING TO MOVE EAST ON
SUNDAY AND SUNDAY NIGHT. STILL HAVE CHANCE OR LIKELY POPS GOING
SUNDAY WITH CHANCE POPS OVER THE SOUTHEAST HALF THE CWA ON SUNDAY
EVENING. THEREAFTER...STILL LOOKS FAIRLY ACTIVE FOR EARLY
SEPTEMBER. GLOBAL MODELS ARE SHOWING ZONAL FLOW OVER THE NORTHERN
HALF OF THE NATION WHICH WILL BRING A SHORTWAVE ACROSS THE AREA
TUESDAY INTO WEDNESDAY. THERE IS SOME DIFFERENCES BETWEEN THE
GFS/ECMWF LATER IN THE WEEK WITH HOW QUICKLY A TROUGH WILL DIG INTO
THE CENTRAL U.S.. FOR NOW WILL HAVE A CHANCE OF SHOWERS/
THUNDERSTORMS GOING LATE WEEK INTO EARLY NEXT WEEKEND.
BRITT
&&
.AVIATION...
ISSUED AT 1238 PM CDT SAT SEP 1 2012
LOW PRESSURE SYSTEM IS LOCATED JUST SW OF KCOU AT 1700Z WITH MVFR
CONDITIONS NEARLY DOMINATING MOST OF THE REGION. A SMALLER AREA OF
IFR IS LOCATED MORE CONCENTRATED AROUND THE LOW PRESSURE CENTER.
EXPECTING THE LOW TO MOVE EASTWARD THROUGH THE PERIOD AND BE
LOCATED NEARLY OVER ST. LOUIS AT 06Z AND IN SE IL BY 18Z SUNDAY.
SCATTERED SHOWERY LIGHT PRECIPITATION IS EXPECTED THROUGH TONIGHT
WITH THE MAIN THREAT OF THUNDERSTORMS FROM ST LOUIS EASTWARD FROM
THE AFTERNOON INTO THE EVENING. LOWER CIGS WILL SPREAD FROM WEST
TO EAST IN ASSOCIATION WITH THE LOW...AND EXPECTING WIDESPREAD IFR
CONDITIONS TO EVENTUALLY BLANKET THE AREA TONIGHT. CIGS HEIGHTS
WILL GRADUALLY IMPROVE ON SUNDAY FROM WEST TO EAST FROM MID-
MORNING INTO THE AFTERNOON.
SPECIFICS FOR KSTL...
MVFR CONDITIONS EXPECTED THROUGH THE EARLY EVENING WITH BANDS OF
LIGHT SHOWERS. AFTER 20Z WE ARE EXPECTING ADDITIONAL THUNDERSTORMS
AND AM NOT SURE IF THEY WILL FORM OVER ST. LOUIS OR FURTHER EAST.
AT THIS TIME KEPT WITH A VCTS MENTION. IFR CIGS SHOULD SETTLE INTO
THE AREA TONIGHT AS THE LOW PRESSURE SYSTEM APPROACHES AND MOVES
OVER KSTL. CIGS HEIGHTS WILL IMPROVE ON SUNDAY AFTERNOON INTO THE
MVFR FLIGHT CAT AS THE LOW MOVES EAST AND TOWARDS THE OHIO VALLEY.
GLASS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1246 PM CDT SAT SEP 1 2012
...UPDATED AVIATION DISCUSSION...
.UPDATE...
Recent satellite observations indicate that Isaac is now
post-tropical, with the center of circulation now over Osceola, MO
and drifting southeast. Cloud tops within a broad deformation zone
have warmed considerably since 12Z as the system is merging with an
increasingly diffuse frontal zone, while the connection to the Gulf
is also being lost due to dry air entrainment over the Mid
Mississippi Valley.
All in all, the rain that has been anchored from southwest of Kansas
City northeastward toward Kirksville will gradually weaken in
intensity and shift slowly eastward this afternoon. Still an
effective washout for areas east of an Atchison KS to Grant City, MO
line, but additional amounts should average less than a third of an
inch, with the exception of areas along the Highway 69 and 71
corridors south of Kansas City where slightly stronger forcing will
persist for several more hours (perhaps another 0.50 to 0.75" here).
This rain could not have been more timely or beneficial, with most
portions of the forecast area seeing anywhere from 2 to 6" over the
past 24 hours. Of more importance is that hourly rainfall amounts
generally averaged 0.10 to 0.30" per hour through that duration. The
poor river/creek response thus far would indicate that a much much
higher than typical percentage of the rainfall has infiltrated the
soil as opposed to runoff, which should yield extensive benefits in
the short term.
While substantial moisture deficits still persist, the remnants of
Isaac have acted not only to deliver much needed rainfall, but
wholly alter the upper flow pattern across the US. In short, the
relocation of the upper ridge along the eastern seaboard and
suppression of its western counter part will allow an extensive
period of fast zonal flow to develop across the local region for the
next week. Within this cooler regime, baroclinity will strengthen
beneath the upper jet, supporting several potential rain chances
over the coming week as Pacific troughs now have a legitimate shot
of reaching the area.
Bookbinder
&&
.PREV DISCUSSION...
/ISSUED 404 AM CDT Sat Sep 1 2012/
Main Concern continues to be the remnants of TD Isaac and potential
for flooding. The GFS has been the best performer for the short term
as NAM and RAP were late in picking up the higher rainfall amounts in
the northwest quadrant of the circulation. This area...a deformation
zone of sorts...has seen upwards of 3.5 inches of rain over the last
12 hours or so. The Johnson County Kansas StormWatch observations
show this along with both the legacy and dual pol storm total
precipitation algorithms. The legacy precip algorithm has actually
underestimated by around a half an inch or so even though the Z-R
relationship was changed to tropical yesterday.
As the circulation continues to mainly wobble around Clinton MO we
should see continued rainfall over the above mentioned area...while
the extreme southern zones will have lesser amounts and probably not
much until the low begins to finally move east this afternoon.
Instability remains too weak to support convection so keeping that
out of the forecast for the short term.
The rain should taper off later this afternoon over the western zones
and by evening over the east. Another concern will be fog chances
overnight but thinking that enough stratus will linger such that will
keep fog out for now but day shift should review.
Sunday will see warming temperatures and drying conditions as 850MB
temperatures rebound and moisture from Isaac makes its way into the
Ohio Valley. Expect upper ridging over the area for Labor Day and
Tuesday so we will see continued highs in the 90s.
A front approaches from the north as the upper ridge is
flattened...courtesy of deepening upper trough over south central
Canada. Therefore we will see some chance of thunderstorms return
about mid week and cooler temperatures later in the week.
Adolphson
&&
.AVIATION...
For the 18Z TAFs, last vestiges of post-tropical Isaac lingering
across the Kansas City terminals early this afternoon.
Showers/sprinkles should end at MCI/MKC by 20Z, with associated MVFR
stratus gradually giving way to a broken mid level cloud deck around
11-12Kft. The latter conditions already exist at STJ and will
continue this afternoon. Winds will remain gusty at times from the
NNW (MKC/MCI) to N (STJ) at 15 to 20 knots, subsiding quickly with
sunset.
Skies should firmly clear overnight with winds diminishing to light
and variable. With no significant boundary layer drying expected, am
thinking that fog (potentially dense) is a good bet early Sunday
morning, and have introduced this into the outlook portion of the
TAFs.
Bookbinder
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1059 AM CDT SAT SEP 1 2012
.UPDATE...
Recent satellite observations indicate that Isaac is now
post-tropical, with the center of circulation now over Osceola, MO
and drifting southeast. Cloud tops within a broad deformation zone
have warmed considerably since 12Z as the system is merging with an
increasingly diffuse frontal zone, while the connection to the Gulf
is also being lost due to dry air entrainment over the Mid
Mississippi Valley.
All in all, the rain that has been anchored from southwest of Kansas
City northeastward toward Kirksville will gradually weaken in
intensity and shift slowly eastward this afternoon. Still an
effective washout for areas east of an Atchison KS to Grant City, MO
line, but additional amounts should average less than a third of an
inch, with the exception of areas along the Highway 69 and 71
corridors south of Kansas City where slightly stronger forcing will
persist for several more hours (perhaps another 0.50 to 0.75" here).
This rain could not have been more timely or beneficial, with most
portions of the forecast area seeing anywhere from 2 to 6" over the
past 24 hours. Of more importance is that hourly rainfall amounts
generally averaged 0.10 to 0.30" per hour through that duration. The
poor river/creek response thus far would indicate that a much much
higher than typical percentage of the rainfall has infiltrated the
soil as opposed to runoff, which should yield extensive benefits in
the short term.
While substantial moisture deficits still persist, the remnants of
Isaac have acted not only to deliver much needed rainfall, but
wholly alter the upper flow pattern across the US. In short, the
relocation of the upper ridge along the eastern seaboard and
suppression of its western counter part will allow an extensive
period of fast zonal flow to develop across the local region for the
next week. Within this cooler regime, baroclinity will strengthen
beneath the upper jet, supporting several potential rain chances
over the coming week as Pacific troughs now have a legitimate shot
of reaching the area.
Bookbinder
&&
.PREV DISCUSSION...
/ISSUED 404 AM CDT Sat Sep 1 2012/
Main Concern continues to be the remnants of TD Isaac and potential
for flooding. The GFS has been the best performer for the short term
as NAM and RAP were late in picking up the higher rainfall amounts in
the northwest quadrant of the circulation. This area...a deformation
zone of sorts...has seen upwards of 3.5 inches of rain over the last
12 hours or so. The Johnson County Kansas StormWatch observations
show this along with both the legacy and dual pol storm total
precipitation algorithms. The legacy precip algorithm has actually
underestimated by around a half an inch or so even though the Z-R
relationship was changed to tropical yesterday.
As the circulation continues to mainly wobble around Clinton MO we
should see continued rainfall over the above mentioned area...while
the extreme southern zones will have lesser amounts and probably not
much until the low begins to finally move east this afternoon.
Instability remains too weak to support convection so keeping that
out of the forecast for the short term.
The rain should taper off later this afternoon over the western zones
and by evening over the east. Another concern will be fog chances
overnight but thinking that enough stratus will linger such that will
keep fog out for now but day shift should review.
Sunday will see warming temperatures and drying conditions as 850MB
temperatures rebound and moisture from Isaac makes its way into the
Ohio Valley. Expect upper ridging over the area for Labor Day and
Tuesday so we will see continued highs in the 90s.
A front approaches from the north as the upper ridge is
flattened...courtesy of deepening upper trough over south central
Canada. Therefore we will see some chance of thunderstorms return
about mid week and cooler temperatures later in the week.
Adolphson
&&
.AVIATION...
For the 12Z TAFs...the remnants of Isaac are rotating across west
central Missouri this morning continuing to bring rain, occasionally
moderate, into the terminals. NAM bufr soundings and MOS guidance as
well as GFS LAMP and MOS guidance support IFR cigs this morning
lifting to MVFR this afternoon as rain comes to an end. MKC will
experience MVFR cigs/vis this morning as well. Rain will come to an
end at MKC this afternoon however MVFR cigs will prevail. STJ will
experience light rain through mid morning with occasional MVFR cigs
however rain will come to an end by mid morning with cigs becoming
VFR by early afternoon. Winds will be gusty around 20-25 knots out
of the north this morning diminishing to around 12kts this afternoon
as Isaac begins to pull off to the east.
73
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
404 AM CDT Sat Sep 1 2012
.DISCUSSION...
Main Concern continues to be the remnants of TD Isaac and potential
for flooding. The GFS has been the best performer for the short term
as NAM and RAP were late in picking up the higher rainfall amounts in
the northwest quadrant of the circulation. This area...a deformation
zone of sorts...has seen upwards of 3.5 inches of rain over the last
12 hours or so. The Johnson County Kansas StormWatch observations
show this along with both the legacy and dual pol storm total
precipitation algorithms. The legacy precip algorithm has actually
underestimated by around a half an inch or so even though the Z-R
relationship was changed to tropical yesterday.
As the circulation continues to mainly wobble around Clinton MO we
should see continued rainfall over the above mentioned area...while
the extreme southern zones will have lesser amounts and probably not
much until the low begins to finally move east this afternoon.
Instability remains too weak to support convection so keeping that
out of the forecast for the short term.
The rain should taper off later this afternoon over the western zones
and by evening over the east. Another concern will be fog chances
overnight but thinking that enough stratus will linger such that will
keep fog out for now but day shift should review.
Sunday will see warming temperatures and drying conditions as 850MB
temperatures rebound and moisture from Isaac makes its way into the
Ohio Valley. Expect upper ridging over the area for Labor Day and
Tuesday so we will see continued highs in the 90s.
A front approaches from the north as the upper ridge is
flattened...courtesy of deepening upper trough over south central
Canada. Therefore we will see some chance of thunderstorms return
about mid week and cooler temperatures later in the week.
Adolphson
&&
.AVIATION...
For the 12Z TAFs...the remnants of Isaac are rotating across west
central Missouri this morning continuing to bring rain, occasionally
moderate, into the terminals. NAM bufr soundings and MOS guidance as
well as GFS LAMP and MOS guidance support IFR cigs this morning
lifting to MVFR this afternoon as rain comes to an end. MKC will
experience MVFR cigs/vis this morning as well. Rain will come to an
end at MKC this afternoon however MVFR cigs will prevail. STJ will
experience light rain through mid morning with occasional MVFR cigs
however rain will come to an end by mid morning with cigs becoming
VFR by early afternoon. Winds will be gusty around 20-25 knots out
of the north this morning diminishing to around 12kts this afternoon
as Isaac begins to pull off to the east.
73
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION...UPDATED
NWS GLASGOW MT
859 AM MDT SAT SEP 1 2012
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH MONDAY...
UPDATE...ADJUSTED WEATHER ELEMENT AND POPS THIS MORNING BASED ON
CURRENT TRENDS. HRRR DOES BRING A FEW ISOLATED SHOWERS AND THUNDER
INTO THE REGION AGAIN THIS AFTERNOON. PROTON
SOUTHWEST FLOW ALOFT WILL PREVAIL OVER MONTANA TODAY AS UPPER LOW
OVER BRITISH COLUMBIA MOVES TO THE EAST. SURFACE LOW NEAR HAVRE AT
09Z WILL MOVE EAST ALONG THE MT/SASK BORDER TODAY. LEE SIDE TROUGH
EXTENDING SOUTHEAST FROM THE LOW WILL SLIDE THROUGH EASTERN
MONTANA THIS MORNING TURNING WINDS FROM EASTERLY TO SOUTH OR
SOUTHWEST. COLD FRONT CURRENTLY IN ALBERTA WILL FOLLOW THIS
EVENING TURNING WINDS TO THE WEST OR NORTHWEST. AIRMASS WILL
BECOME UNSTABLE ENOUGH FOR THUNDERSTORMS TODAY BUT LIMITED
MOISTURE WILL GENERALLY BE LIMITED TO MID AND HIGH LEVEL MONSOONAL
MOISTURE. EXPECT THUNDERSTORM COVERAGE TO BE ISOLATED. VERY DRY
LOW LEVEL AIR MAY ALLOW FOR SOME DOWNBURST WINDS IN ANY STORMS
THAT DEVELOP. LIGHTNING WITH LIMITED RAINFALL WILL MAKE WILDFIRES
A THREAT WITH ANY STORMS THAT OCCUR. WILL MAINTAIN RED FLAG
WARNING TODAY. THERMAL RIDGE WILL KEEP TEMPERATURES WARM BUT
CLOUD COVER MAY LIMIT TEMPERATURES SOMEWHAT TODAY.
THE COLD FRONT MOVES THROUGH EASTERN MONTANA THIS EVENING AND THE
SURFACE LOW BECOMES STACKED WITH THE UPPER LOW OVER ALBERTA AND
SASKATCHEWAN TONIGHT. AFTER THE FRONT MOVES THROUGH...A DRY SLOT
MOVES INTO MONTANA SHUTTING OFF ANY CHANCE FOR RAIN.
GUSTY WEST TO NORTHWEST WINDS WILL DEVELOP BEHIND THE FRONT SUNDAY
MORNING AS THE LOW REMAINS OVER SASKATCHEWAN. WHILE TEMPERATURES
WILL BE ABOUT 10 DEGREES COOLER THAN TODAY...RH WILL BE JUST AS
LOW POSSIBLY LOWER THAN TODAY WITH VERY DRY AIR EXPECTED OVER THE
AREA. EXPECT WINDS 15 TO 30 MPH WITH OCCASIONAL GUSTS UP TO 40
MPH BEHIND THIS FRONT. THE WINDS WILL DIMINISH SUNDAY EVENING WITH
THE LOSS OF DAYTIME HEATING. WILL CONTINUE RED FLAG WARNING
THROUGH SUNDAY. A LAKE WIND ADVISORY WILL LIKELY BE NEEDED FOR
FORT PECK LAKE ON SUNDAY. WILL WAIT UNTIL THE TIMING OF THE WINDS
COME INTO BETTER FOCUS BEFORE ISSUING THE ADVISORY.
THE LOW REMAINS OVER SASKATCHEWAN AND MANITOBA SUNDAY NIGHT AND
MONDAY BUT THE SURFACE GRADIENT RELAXES ALLOWING THE WINDS TO
DIMINISH. LABOR DAY WILL BE A MOSTLY SUNNY DAY WITH LIGHT WINDS
AND SLIGHTLY ABOVE NORMAL TEMPERATURES AFTER A COOL START. FORRESTER
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
TEMPERATURES BEGIN TO TREND COOLER DURING THE EXTENDED PERIOD
WHICH BEGINS MONDAY NIGHT. THE SLOW-MOVING CLOSED UPPER LOW THAT
HAS BEEN SPINNING OVER SOUTHERN BRITISH COLUMBIA WILL HAVE WORKED
ITS WAY INTO CENTRAL SASKATCHEWAN/MANITOBA BY 00Z TUESDAY. ITS
MAIN EFFECT MONDAY NIGHT WILL BE TO NUDGE THE STATIONARY BOUNDARY
SOUTH INTO NORTHEAST MONTANA.
THEN THE LOW SENDS A BACKDOOR COLD FRONT SOUTH TUESDAY. THE END
RESULT WILL BE MOST HIGH TEMPERATURES IN THE 70S OR 5F TO 10F
LOWER THAN NORMAL. TEMPERATURES WILL BE WARMER AROUND THE
YELLOWSTONE RIVER VALLEY WITH HIGHS IN THE LOWER 80S. MODELS
CONTINUE DRY BUT THE BACKDOOR FRONT COULD KNOCK OUT SOME LIGHT
RAIN SHOWERS. ANOTHER AFFECT OF THE FRONT WILL BE 20KT NW WINDS.
MIXING DOWN OF 700MB WINDS OF 30KTS WILL ADD WIND GUSTS. TUESDAY
NIGHT 700MB TEMPERATURES WITH CAA WILL RUN AROUND 0C ALONG THE
INTERNATIONAL BORDER FOR A COOLER NIGHT.
WEDNESDAY NIGHT AND BEYOND...THE GFS AND THE EC PICK UP ANOTHER
COOL SHORTWAVE DROPPING SOUTH FROM CANADA. MODELS SUGGEST A GOOD
SLUG OF MOISTURE WITH THIS WAVE...SOMETIME AROUND THURSDAY NIGHT
AFFECTING THE AREA. TEMPERATURES WILL REMAIN SLIGHTLY COOLER THAN
NORMAL INTO THE WEEKEND. A BUILDING RIDGE IN THE WEST WILL LIKELY
WARM TEMPERATURES AGAIN FOR THE FOLLOWING WEEK. SCT
&&
.AVIATION...
EXPECT MOSTLY VFR CONDITIONS FOR THIS TAF PERIOD...WITH SOME
INTERMITTENT MVFR VISIBILITIES POSSIBLE DUE TO HAZE/SMOKE FROM
WILDFIRES AROUND THE AREA. THIS SMOKE/HAZE IS NOT EXPECTED TO EXIT
THE AREA UNTIL A COLD FRONT PASSAGE LATER TODAY SHIFTS WIND AROUND
TO THE NORTHWEST. HIGH BASED THUNDERSTORMS ARE POSSIBLE ACROSS THE
REGION TODAY WHICH COULD PRODUCE STRONG ERRATIC WIND GUSTS.
BMICKELSON
&&
.FIRE WEATHER...
CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED TODAY AND SUNDAY.
FOLLOWING POOR RH RECOVERY OVERNIGHT IN MANY AREAS (25 TO 50
PERCENT AS OF 3 AM MDT)...HUMIDITIES WILL FALL INTO THE TEENS
AGAIN THIS AFTERNOON ACROSS NORTHEAST MONTANA. WINDS WILL BE
MAINLY EAST TO SOUTHEAST AROUND 10 MPH THIS MORNING BECOMING
VARIABLE THIS AFTERNOON. A COLD FRONT IS EXPECTED THIS EVENING
WITH NORTHWEST WINDS 10 TO 20 MPH. CONDITIONS WILL BECOME UNSTABLE
BY AFTERNOON AND ISOLATED THUNDERSTORMS SHOULD DEVELOP. THESE
THUNDERSTORMS WILL BECOME GOOD LIGHTNING PRODUCERS ACROSS EASTERN
MONTANA. ANY FIRES STARTED BY LIGHTNING WILL BE IMPACTED BY THIS
SUDDEN SHIFT AND CHANGE IN WIND SPEED AND STRENGTH. WEST TO
NORTHWEST WINDS WILL INCREASE TO 15 TO 30 MPH SUNDAY MORNING WITH
HUMIDITIES ONCE AGAIN FALLING INTO THE TEENS SUNDAY AFTERNOON.
FORRESTER
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 9 PM MDT SUNDAY FOR MTZ120-122-134>137.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1041 PM EDT SUN SEP 2 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE SLOWLY EASTWARD THROUGH THE OHIO VALLEY ON
SUNDAY...MONDAY...AND TUESDAY. A WEAK COLD FRONT WILL CROSS THE
AREA ON WEDNESDAY...WITH HIGH PRESSURE BUILDING IN FOR THE END OF
THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
BROKEN BAND OF SHOWERS ARC FROM NEAR RICHMOND INDIANA...DOWN TO
EAST OF CINCINNATI TO NR JACKSON KY IS FORECAST TO CONTINUE TO
PIVOT N TO NE OVERNIGHT. LATEST RUNS OF THE RAP AND NAM MODELS ARE
SUGGESTING THAT IT WILL WEAKEN/BREAK UP AS THE NIGHT
PROGRESSES...SO TRENDED THE FORECAST THAT WAY. KEPT SOME HIGHER
CHC POPS IN THE S BY 12Z...WITH MAINLY SLIGHT CHC POPS IN THE N.
DIDNT ADJUST LOWS FOR TONIGHT AS THEY LOOK ON TRACK. KEPT THEM IN
THE UPPER 60S TO LOWER 70S.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/...
THE EXPECTED EASTWARD MOVEMENT OF THE WEAKENING SURFACE LOW
APPEARS SLOWER ON THE MODEL RUNS TODAY...NECESSITATING LIKELY POPS
AT ALL LOCATIONS ON MONDAY AFTERNOON. THE ATMOSPHERIC MOISTURE
SITUATION WILL NOT CHANGE MUCH...SO HEAVY RAIN WILL AGAIN BE A
POSSIBILITY.
AS POST-ISAAC DISSOLVES AND BECOMES ABSORBED IN THE MEAN
FLOW...THERE ARE SOME SLIGHT TIMING DISAGREEMENTS IN HOW QUICKLY
THE MOISTURE AND FORCING WILL DEPART THE AREA ON TUESDAY. TAKING A
BLENDED APPROACH TO THE TIMING...IT DOES APPEAR THAT LIKELY POPS
WILL BE WARRANTED IN THE EASTERN CWA AS THE DIURNAL CYCLE TAKES
EFFECT.
TEMP FORECAST CHANGES WERE MINIMAL FOR MONDAY AND MONDAY NIGHT. WITH
GREATER EXPECTED CLEARING IN THE WEST ON TUESDAY...MAX TEMPS HAVE
BEEN INCREASED...ESPECIALLY WEST OF I-75.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
A BLEND OF HPC AND THE 00Z ECMWF WAS USED FOR THE LONG TERM
FORECAST.
THE REMNANTS OF ISAAC SHOULD EVENTUALLY MOVE EAST OF THE REGION
TUESDAY NIGHT WITH DECREASING CHANCES OF PCPN.
FOR WEDNESDAY...REGION WILL BE IN A RELATIVE A LULL. MODELS INDICATE
THAT A S/WV MAY PUSH ACRS THE REGION WEDNESDAY AFTN AND EVENING
AHEAD OF A COLD FRONT. THIS WILL WARRANT LOW CHANCE POPS ATTM.
TEMPERATURES WILL WARM INTO THE MID 80S TO NEAR 90.
A STRONGER S/WV IS FORECAST TO MOVE ACRS THE NRN GREAT LAKES
WEDNESDAY NIGHT AND THURSDAY. THIS WILL PUSH A WEAK COLD FRONT
ACROSS THE AREA. THERE WILL REMAIN A LOW CHANCE OF SHOWERS AND
THUNDERSTORMS UNTIL THIS PASSES.
HIGH PRESSURE WILL BRIEFLY BUILD IN THURSDAY NIGHT INTO THE FIRST
PART OF FRIDAY. WHILE THERE IS SOME DISCREPANCY IN MODEL SOLUTIONS
BY THE END OF THE WEEK...THERE ARE INDICATIONS THAT ANOTHER MORE
VIGOROUS SHORT WAVE WILL AFFECT THE REGION FRIDAY NIGHT AND
SATURDAY. THIS SYSTEM AND ITS ASSOCIATED LOW PRESSURE AND COLD FRONT
WILL HAVE TEMPERATURE IMPLICATIONS DEPENDING ON HOW IT DEVELOPS AND
MOVES ACRS THE OHIO VALLEY.
MODELS INDICATE THAT AFOREMENTIONED UPR LVL ENERGY MAY EVOLVE INTO A
CLOSED LOW OVER THE REGION FOR THE FIRST PART OF NEXT WEEK. THIS MAY
ALLOW A FEW SHOWERS TO LINGER.
TEMPERATURES WILL SHOW A GRADUAL COOLING TREND THROUGH THE PERIOD.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
BAND OF CONVECTION THAT HAS BEEN AFFECTING ERN KY HAS LIFTED INTO THE
CVG/LUK TAFS AND EXTENDS UP THE OHIO RIVER TOWARDS HTS. EXPECT
THIS AREA TO CONTINUE TO LIFT N OVER THE NEXT SEVERAL
HOURS...REACHING THE ILN TAF. HAVE CIGS AND VSBYS DROPPING TO MVFR
WITH SOME GUSTS TO 30 KTS. TREND OF THE MODELS IS FOR THE
CONVECTION TO WEAKEN THRU 03Z...SO NOT SURE IT WILL REACH DAY OR
CMH/LCK. ONLY HAVE VCSH FOR THEM THIS EVENING.
MODELS TIME SERIES ARE SHOWING THAT CIGS WILL LOWER OVERNIGHT
ACROSS THE WRN TAFS...FIRST TO MVFR...THEN TO IFR BY 08Z. KEPT THE
CIGS VFR IN THE E WHERE THE PCPN HAS BEEN MORE SPARSE.
CIGS SHOULD LIFT BACK TO VFR ON MONDAY. WITH SFC AND UPPER LEVEL
CIRCULATION OF ISAAC STILL IN THE OH VALLEY...SHOULD SEE POP UP
SHRA AGAIN. ONLY WENT VCSH ON MONDAY AS EXPECT THEM TO BE SIMILAR
TO TODAY.
.OUTLOOK...MVFR CEILINGS AND VISIBILITIES POSSIBLE MONDAY NIGHT
AND TUESDAY. THUNDERSTORMS ARE POSSIBLE WEDNESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...SITES
SHORT TERM...HATZOS
LONG TERM...HICKMAN
AVIATION...SITES
AREA FORECAST DISCUSSION...UPDATED
NWS CLEVELAND OH
941 PM EDT SUN SEP 2 2012
.SYNOPSIS...
THE REMNANTS OF ISAAC WILL MOVE EAST ACROSS THE OHIO VALLEY THROUGH
TUESDAY WITH A HUMID AIRMASS AND PERIODS OF HEAVY RAIN. A WEAK FRONT
WILL HELP TO DRY US OUT ON TUESDAY NIGHT WITH A STRONGER COLD
FRONT WITH AN AIRMASS CHANGE PUSHING SOUTH ACROSS THE AREA ON
THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
CUT POPS BACK TO CHANCE POPS SW OF A FDY-MFD LINE AND REMOVED
MENTION OR PRECIP NE OF THE SAME LINE. SHOWERS APPROACH AREA AND
DIE AS THEY ARE BEING SQUASHED BY SOME UPPER LEVEL SUBSIDENCE
FROM 300 MB JET. ALSO REMOVED MENTION OF THUNDER. TWEAKED TEMPS
SLIGHTLY.
ORIGINAL DISCUSSION...
STILL MAY GET SOME SHOWERS/THUNDERSTORMS TO DEVELOP THIS EVENING.
WHILE INSTABILITY IS NOT AS GOOD AS YESTERDAY IT SEEMS THAT CAPE
OF 2K IS ENOUGH TO GET SOME STORMS TO POP IN NORTHERN INDIANA.
WILL KEEP THE LIKELY POPS FROM FDY TO MNN TO MT VERNON FOR THIS
EVENING...WITH LESS OF A CHANCE ACROSS THE REST OF OH AND STILL
DRY ACROSS NW PA. FLASH FLOOD GUIDANCE IS LOW /AROUND ONE INCH IN
THREE HOURS/ FROM THE RAIN LAST NIGHT ACROSS THE FAR SOUTHWEST.
ANY THUNDERSTORMS THAT DO DEVELOP THIS EVENING WILL HAVE THE
POTENTIAL FOR HEAVY RAIN BUT WE HAVE HAD ALL DAY RAIN FREE THERE
TO ALLOW THE WATER TO RECEDE. WIDESPREAD FLOODING TO PROMPT A
FLASH FLOOD/FLOOD WARNING IS NOT EXPECTED. ISOLATED MINOR
FLOODING COULD OCCUR. THE REMAINDER OF THE NIGHT LOOKS DRIER THAN
NOT AND JUST LINGER LOW PRECIP CHANCES THROUGH THE NIGHT. DID NOT
MENTION THUNDER OVERNIGHT EITHER BASED MORE ON SREF PROB. MORE
HUMID AIR IS STARTING TO CREEP INTO NW PA WITH MID 60S DEWPOINTS
AT GKJ/MEADVILLE. SO WHILE ERI MAY STILL HAVE A RELATIVELY
COMFORTABLE NIGHT...THE REST OF NRN OH WILL BE WARM AND HUMID
TONIGHT. LOWS WILL BE SIMILAR TO LAST NIGHT. WE WILL KEEP THE
OVERCAST SKIES.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY NIGHT/...
LOW SPINNING ACROSS ILLINOIS WILL CONTINUE TO FILL AND DRIFT EAST-
SOUTHEAST OVER THE NEXT TWO DAYS. COVERAGE OF SHOWERS/TS COULD BE
ON THE UPTICK FOR MONDAY. HAVE MAINTAINED SOME OF THE LIKELY POPS
ESPECIALLY ACROSS THE SOUTH AND SOUTHEAST. STUCK WITH SIMILAR
HIGHS FOR TOMORROW. UPPER TROUGH BEGINS TO OPEN UP AND WITH SOME
DIURNAL HEATING TS SHOULD POP UP. WILL HAVE TO CONTINUE THE PRECIP
CHANCES INTO MONDAY NIGHT. AT THIS POINT WE WILL BE GETTING SOME
EXTRA UPPER SUPPORT IN THE FORM OF A SHORTWAVE/JET COMING ACROSS
THE GREAT LAKES. THE COLD FRONT WILL MOVE ACROSS TUESDAY. WE WILL
STILL HAVE TO BE ON THE LOOKOUT FOR HEAVIER RAINFALL ESPECIALLY
LATER MONDAY NIGHT AND TUESDAY WITH BETTER FOCUSING MECHANISMS
LOCALLY. LOCALIZED FLOODING WILL STILL BE A CONCERN THROUGH
TUESDAY.
WEDNESDAY LOOKS LIKE THE FIRST GOOD DRY/IN BETWEEN SYSTEMS DAY.
WEAK HIGH PRESSURE OVER THE AREA AND SOME SUN SHOULD BE ABLE TO
BRING TEMPS UP INTO THE MID 80S...OR MAYBE EVEN SOME UPPER 80S. WE
WILL NOT GET A GOOD AIRMASS CHANGE UNTIL AFTER WEDNESDAY NIGHT
WITH THE NEXT SYSTEM IN THE EXTENDED.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A COLD FRONT WILL MOVE ACROSS THE REGION THURSDAY WITH SOME
SCATTERED SHOWERS AND THUNDERSTORMS ANTICIPATED. THE FRONT SHOULD
CLEAR THE ENTIRE REGION BY THURSDAY EVENING. THIS WILL ALLOW HIGH
PRESSURE TO RETURN FOR FRIDAY. THIS LOOKS TO BE SHORT LIVED AS THE
NEXT TROUGH MOVES INTO THE WESTERN GREAT LAKES ON FRIDAY.
TEMPERATURES WILL BE NEAR TO SLIGHTLY ABOVE SEASONAL AVERAGES ON
THURSDAY. COOLER IN THE WAKE OF THE FRONT FOR FRIDAY INTO SATURDAY
WITH HIGHS GENERALLY IN THE MIDDLE TO UPPER 70S.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
SATELLITE LOOP SHOWS THE CENTER OF THE REMNANTS OF ISAAC OVER SERN
IL AT 23Z WITH RADAR SHOWING CONVECTION FROM CENTRAL INDIANA
THROUGH THE KDAY VICINITY INTO SERN OHIO. MORE CONVECTION IS
MOVING NORTH OUT OF KY. ACROSS NWRN OHIO AND NWRN PA CONDITIONS
RANGE FROM MOSTLY VFR FAR EAST TO VFR/MVFR WEST AND SOUTH.
DEWPOINTS 65 TO 70 ACROSS MUCH OF THE AREA WITH LOWER 70S IN KFDY
AND UPPER 50S KERI. FOLLOWING THE HRRR HIGH RESOLUTION MODEL HAVE
KEPT PRECIP OUT OF THE AREA OVERNIGHT. BEST CHANCES HOWEVER WOULD
BE FROM KFDY TO KMFD IF THE BAND DID MANAGE TO REACH THE AREA.
MAIN CONCERN OF THE OVERNIGHT WOULD BE LOWERING CIGS AND
VISIBILITIES IN FOG AND STRATUS WITH DEEP MOISTURE ACROSS THE
AREA. DID BRING TAFS DOWN THROUGH MVFR AFTER MIDNIGHT TO MVFR/IFR
AROUND SUNRISE. AT KERI...WINDS EXPECTED TO TURN SE OVERNIGHT
WHICH WOULD BRING MORE MOISTURE INTO THE AREA SO DID BRING MVFR
CONDITIONS THERE OVERNIGHT AS WELL. ON MONDAY MODELS SHOW
CIRCULATION MOVING SE IN KY. BEST CHANCE FOR CONVECTION GETTING
INTO THE AREA WOULD BE THE SOUTH CENTRAL COUNTIES OF THE CWA. FOR
NOW BROUGHT VCTS TO THE AREA AT KMFD AND KCAK FOR THE AFTERNOON.
.OUTLOOK...NON VFR POSSIBLE MONDAY NIGHT AND TUESDAY WITH
OVERNIGHT AND EARLY MORNING FOG AS WELL AS SCATTERED TO NUMEROUS
SHOWERS/THUNDERSTORMS.
&&
.MARINE...
WINDS HAVE INCREASED TO AROUND 15 KNOTS FOR THE OPEN WATERS AND A
PORTION OF THE NEARSHORE WATERS FROM CONNEAUT TO RIPLEY. THIS HAS
CAUSED SOME LOCALLY HIGHER WAVES FOR THE ERIE AREA WITH 2 TO 4 FOOT
WAVES A DECENT BET INTO THE EVENING. WINDS SHOULD DECREASE THIS
EVENING WITH WAVES DECREASING.
OTHERWISE WE CONTINUE TO WATCH LOW PRESSURE THAT WILL TRACK ALONG
THE OHIO RIVER VALLEY INTO MONDAY NIGHT. THIS WILL KEEP AN EASTERLY
FLOW ON THE LAKE UNTIL A WEAKENING COLD FRONT PASSES ON TUESDAY.
WINDS WILL SHIFT AROUND TO THE NW AND NORTH WITH THE FRONTAL
PASSAGE. WINDS AT THIS POINT DO NOT LOOK STRONG ENOUGH TO NEED A
SMALL CRAFT ADVISORY.
HIGH PRESSURE WILL TAKE CONTROL OF LAKE ERIE TUESDAY NIGHT INTO
WEDNESDAY. A STRONGER COLD FRONT LOOKS TO ARRIVE ON THURSDAY WITH
SOME GUSTY NW WINDS POSSIBLE. THE STRONGER WINDS MAY NOT ARRIVE
UNTIL THURSDAY NIGHT AS HIGH PRESSURE BUILDS ONTO THE WESTERN END OF
THE LAKE.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DJB/OUDEMAN
NEAR TERM...OUDEMAN
SHORT TERM...OUDEMAN
LONG TERM...MULLEN
AVIATION...TK
MARINE...MULLEN
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1006 AM EDT SAT SEP 1 2012
.SYNOPSIS...
A WEAK COLD FRONT ALONG THE SOUTH SHORE OF LAKE ERIE IS EXPECTED
TO MOVE SOUTH TO CENTRAL OHIO LATER TODAY AND THEN STALL. THE
REMNANTS OF ISAAC OVER MISSOURI THIS MORNING WILL MOVE SLOWLY EAST
ALONG THE FRONT AND ACROSS THE UPPER OHIO VALLEY ON MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MINOR ADJUSTMENTS MADE TO THE FORECAST. AREAS SOUTH OF US 30 HAVE
THE BEST SHOT AT SCATTERED/ ON AND OFF SHOWERS/TS TODAY. FRONT HAS
SLIPPED SOUTH OF THE LAKESHORE AND HAVE USED ITS CURRENT POSITION
TO DELINEATE THE BETTER PRECIP CHANCES TO THE SOUTH. HRRR SHOWING
WIDESPREAD PRECIP SOUTH OF A LINE FROM KTOL TO KYNG BY LATE THIS
AFTERNOON. FRONT IS AS FAR SOUTH AS IT IS GOING TO GET. WILL KEEP
AN EYE ON INSTABILITY FOR THIS AFTERNOON WITH THIS WIDESPREAD BKN
TO OVC SKY WANTING TO LIMIT IT. TEMPS WILL ALSO BE IN THE 80 TO
85 RANGE...BUT IT WILL BE HUMID ESPECIALLY ACROSS THE CENTRAL AND
SOUTHWEST COUNTIES. ACROSS NW PA...MAY GET SOME DRIER AIR PUSH
DOWN WITH THE HIGH NORTH OF THE LAKES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
MODELS SIMILAR IN TRACKING WHAT`S LEFT OF ISAAC ACROSS THE REGION
ON MONDAY. EXPECT MOISTURE TO SURGE NORTH INTO THE AREA AHEAD OF
THE LOW. PWAT VALUES WILL BE AT OR ABOVE 2 INCHES THE NEXT SEVERAL
DAYS SO THE POTENTIAL EXISTS FOR LOCALLY HEAVY RAINFALL. ABOUT THE
SW 1/2 OF THE AREA CAN EXPECT BETWEEN 1 AND 2 INCHES OF RAINFALL
WITH LOCALLY HEAVIER AMOUNTS POSSIBLE WHERE THE STRONGER BANDS
PERSIST. PRECIP TOTALS WILL DROP OFF QUICKLY TO THE NE. GIVEN
RECENT DRY SPELL AND LOW WATER LEVELS SEE NO NEED FOR ANY FLOOD
HEADLINES. THE PRECIP MAY DROP OFF SOME SUNDAY NIGHT BUT BY
DAYBREAK MONDAY WILL AGAIN NEED LIKELY WORDING ALL AREAS. WILL
CONTINUE TO MENTION THUNDER AS WELL GIVEN UNSTABLE AIRMASS. THE
SURFACE LOW WILL BE NE OF THE AREA BY DAYBREAK TUESDAY AND EXPECT
PRECIP TO QUICKLY DIMINISH FROM WEST TO THE EAST DURING THE DAY.
WEAK COLD AIR ADVECTION BEHIND THE LOW MAY BE ENOUGH TO KICK OFF A
FEW LIGHT SHOWERS INTO TUESDAY NIGHT. HAVE STAYED CLOSE TO
GUIDANCE TEMPS AGAIN TODAY.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AN UPPER LEVEL TROUGH OVER CENTRAL CANADA WILL PUSH EAST ACROSS THE
GREAT LAKES REGION FROM WEDNESDAY INTO THURSDAY. SOUTHERLY FLOW
AHEAD OF THIS FEATURE ON WEDNESDAY WILL HELP TEMPERATURES WARM INTO
THE MID AND UPPER 80S. WILL HOLD ONTO A LOW CHANCE OF
SHOWERS/THUNDERSTORMS AHEAD OF THE TROUGH ACROSS NW OHIO ON
WEDNESDAY...EXPANDING EAST ACROSS THE FORECAST AREA ON THURSDAY. A
COLD FRONT PUSHES SOUTH ACROSS THE AREA ON THURSDAY NIGHT WITH DRY
NORTHWESTERLY FLOW AND BUILDING HIGH PRESSURE FOR THE END OF THE
WEEK. TEMPERATURES WILL DROP BACK TO NEAR OR BELOW NORMAL VALUES.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
MOISTURE ASSOCIATED WITH THE REMNANTS OF ISAAC WILL CONTINUE TO
INCREASE FROM THE SOUTHWEST TODAY. A LEADING BAND OF SHOWERS WILL
CONTINUE TO IMPACT FDY OVER THE NEXT HOUR OR SO BEFORE WEAKENING
AS IT APPROACHES MFD. ADDITIONAL BANDS OF SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO APPROACH FDY/TOL/MFD THIS AFTERNOON
WITH A MOIST AND UNSTABLE AIRMASS IN PLACE WITH THE MOST LIKELY
TIMING BETWEEN 18-22. ANY THUNDERSTORMS THAT IMPACT THE AIRPORTS
THIS AFTERNOON WILL BE CAPABLE OF PRODUCING HEAVY RAINFALL. THERE
IS A LESSER CHANCE OF CONVECTION DEVELOPING FURTHER EAST AS DRIER
AIR TRIES TO PUSH SOUTH BEHIND A WEAK FRONT. SOME DECREASE IN THE
COVERAGE OF SHOWERS AND THUNDERSTORMS IS EXPECTED OVERNIGHT BEFORE
THE DEEPER MOISTURE APPROACHES ON SUNDAY. HIGH LOW LEVEL MOISTURE
MAY RESULT IN MVFR VISIBILITIES AFTER 06Z TONIGHT.
.OUTLOOK...NON VFR POSSIBLE SUNDAY THROUGH TUESDAY FROM THE MOISTURE
ASSOCIATED WITH THE REMNANTS OF ISAAC AND AN APPROACHING COLD
FRONT.
&&
.MARINE...
EASTERLY WINDS WILL CONTINUE ON LAKE ERIE THROUGH THE LABOR DAY
WEEKEND AS LOW PRESSURE ASSOCIATED WITH THE REMNANTS OF ISAAC SLOWLY
MOVES EAST ACROSS THE OHIO VALLY. WINDS AND WAVES WILL BE RELATIVELY
LIGHT THROUGH THE PERIOD WITH CHANCES OF RAIN INCREASING THROUGH
MONDAY. SCATTERED SHOWERS OR THUNDERSTORMS WILL BE CONFINED TO AREAS
FROM CLEVELAND WESTWARD TODAY...EXPANDING EAST ACROSS THE LAKE ON
SUNDAY AND BECOMING MORE WIDESPREAD ON MONDAY. ANY SHOWERS OR
THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE VERY HEAVY
RAINFALL.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...KUBINA/OUDEMAN
SHORT TERM...KUBINA
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION...CORRECTED
NWS WILMINGTON OH
935 AM EDT SAT SEP 1 2012
.SYNOPSIS...
THE REMNANTS OF ISAAC WILL SLOWLY MEANDER EAST TOWARDS THE AREA
THROUGH THE HOLIDAY WEEKEND RESULTING IN UNSETTLED CONDITIONS. THE
LOW WILL FINALLY MOVE EAST OF THE REGION ON TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
REMNANT TROPICAL DEPRESSION ISAAC /BECOMING EXTRATROPICAL AS WE
SPEAK/ CONTINUES TO SPIN NWRD ACRS WRN MO. PRIMARY BAND OF RAIN
EAST OF CYCLONE IS EJECTING EWRD ACRS WRN IND. NW TO SE ORIENTED
BAND OF SHRA/TSRA OVER CNTL OH IS PUTTING DOWN LOCALLY HEAVY
RAINFALL AMOUNTS EAST OF CMH AND IS BEING WATCHED CLOSELY FOR
SHORT TERM RUNOFF ISSUES /FLASH FLOOD WARNINGS/.
01.12Z KILN RAOB SAMPLED A VERY JUICY TROPOSPHERE WITH PW AT 2.02
INCHES WHICH IS A LITTLE OVER 2 STD ABOVE CLIMO. MOIST ADIABATIC
LAPSE RATES IN THE MID LEVELS...TALL SKINNY CAPES /1500 J/KG/ FOR
PARCELS LIFTED JUST ABOVE THE SFC. WARM CLOUD DEPTHS AROUND 3.6KM
AREN/T AS HIGH AS ANTICIPATED...BUT STILL A VERY EFFICIENT RAINFALL
ENVIRONMENT.
MORNING/RECENT RAP RUNS HAVE A DEFINED 850MB CONVERGENCE ZONE
SUPPORTING THE CNTL OH CONVECTION AND PERSISTS THIS CONVERGENCE
INTO THE NOON HOUR. THIS IS NEAR THE TOP OF THE MID/UPPER LEVEL
S/W RIDGE DOWNSTREAM OF ISAAC...THE IDEAL BREEDING GROUND FOR
REGENERATIVE CONVECTION. THUS...GIVEN AMBIENT AIRMASS AND HIGH
REFLECTIVITIES REMAINING BELOW THE FREEZING LEVEL /WARM RAIN
PROCESSES/ WILL NEED TO WATCH CLOSELY FOR FLASH FLOOD POTENTIAL
EAST/SOUTHEAST OF CMH IN NEXT COUPLE OF HOURS. RAP/NAM INDICATE AS TD
ISAAC PLODS SLOWLY EAST TODAY...THAT DEEPER SLY FLOW SHOULD PUSH THIS
CONVERGENCE MAX NWRD AS IT BREAKS DOWN...SO HOPING THAT IS THE
CASE.
OTHERWISE...WITH DEEP MOISTURE AND LOW CONVECTIVE TEMPS EXPECT DIM
SUN THROUGH THICK CIRRUS SHOULD ALLOW WEAKLY FORCED/DIURNALLY
DRIVEN DOWNPOURS OVER MUCH OF THE AREA THROUGH THE DAY. ALREADY
SEEING THIS OVER NRN KY/SRN IND...SO MAINTAINED THE HIGH AFTN RAIN
CHANCES. NOT TO MENTION THE BAND OF RAIN ENCROACHING INTO WRN/CNTL
IND...WHICH TIME LAGGED RAP/NAM ENSEMBLE SHOWING HAS A HIGH
PROBABILITY OF ENTERING WRN OH AFTER 1 OR 2 PM. A VERY MUGGY DAY
THAT WILL NOT BE A COMPLETE WASHOUT...BUT WILL HAVE A FAIR SHARE
OF RADAR ACTIVITY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
REMNANTS OF ISAAC CENTERED TO THE WEST WILL EVER SO SLOWLY MAKES
ITS WAY TOWARDS THE FORECAST AREA THROUGH THE PERIOD. THERE IS
ABUNDANT MOISTURE IN PLACE AHEAD OF THIS SYSTEM. SO ONLY WEAK
FORCING WILL BE NEEDED TO GENERATE PRECIPITATION.
IT APPEARS THAT AN OLD EAST-WEST BOUNDARY NEAR THE NORTHERN ZONES
MAY SERVE AS A PRIMARY FOCUS TONIGHT. THEN THE FOCUS WILL SHIFT TO
IMPULSES ROTATING AROUND THE MAIN SYSTEM. AS THE STACKED LOW GETS
CLOSER THE SHOWERS SHOULD PROGRESS FROM OFF AND ON TO MORE
PERSISTENT LATE SUNDAY INTO SUNDAY NIGHT. THE UPPER SYSTEM WILL
TRANSITION TO AN OPEN WAVE ON MONDAY AND THAT ADDS UNCERTAINTY TO
THE SYSTEM EVOLUTION. SO BACKED OFF ON POPS SLIGHTLY AT THAT TIME.
BUT IT IS CERTAINLY QUITE POSSIBLE THAT SHOWERS WILL STILL BE
RATHER WIDESPREAD MONDAY WITH GUIDANCE SUGGESTING THAT SOUTHERN
COUNTIES WOULD GET MORE ON THE HOLIDAY.
STILL THINKING THAT RAINFALL AMOUNTS FOR THE ENTIRE EVENT WILL
MAINLY RANGE FROM 1 TO 3 INCHES. THIS SHOULD BE A BENEFICIAL RAIN
FOR THE MOST PART. BUT CANNOT RULE OUT LOCALIZED FLASH FLOODING
FROM ANY STRONGER CONVECTION THAT MAY DEVELOP AS THESE WOULD BE
VERY EFFICIENT RAIN PRODUCING STORMS.
SHOULD NOT BE A LOT OF VARIATION IN TEMPERATURES WITH A DIURNAL
RANGE OF 10 DEGREES OR LESS. WENT ABOVE MOS FOR LOWS AND AT OR
SLIGHTLY BELOW COOLER NAM MOS FOR HIGHS.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
COULD STILL SEE SOME SHOWERS AND THUNDERSTORMS MONDAY NIGHT INTO
TUESDAY AS THE LOW CONTINUES TO TRANSITION AND MOVE OFF TO THE
EAST OF THE REGION. FLOW WILL BE FAIRLY ZONAL THROUGH THE REST OF
THE WEEK. A SHORT WAVE WILL PUSH A COLD FRONT ACROSS THE AREA
WEDNESDAY OR WEDNESDAY NIGHT. THEN HIGH PRESSURE WILL BUILD IN
WITH DRIER AND COOLER CONDITIONS FOR THE LATTER PART OF THE WEEK.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
BANDS OF SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP TODAY IN
OUTER BANDS AHEAD OF ISAAC AND DIURNALLY ESPECIALLY IN THE
SOUTHWEST FCST AREA AS THE OUTGOING RIDGE CONTINUES TO PUSH OUT
AND BREAK DOWN. THE DAY CERTAINLY WONT BE A WASH OUT...BUT MORE
LIKE AREAS OF SHOWERS. NOT EXPECTING HEAVY PRECIP RESULTING IN
MVFR CIGS NOR VSBYS...THOUGH POSSIBLE IN THE ISOLATED BRIEF
THUNDERSTORMS TODAY. AFTER SOME DIMINISHING NEAR 00Z...THE HEAVIER
PRECIPITATION FROM ISAAC APPROACHES AFTER 00Z...SO BETTER CHANCE
FOR MVFR CIGS/VSBYS IN MODERATE RAINFALL.
.OUTLOOK...MVFR CEILINGS AND VISIBILITIES...WITH LOCAL IFR
VISIBILITIES...WILL BE POSSIBLE WITHIN SHOWERS AND EMBEDDED
THUNDERSTORMS THROUGH TUESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...BINAU
SHORT TERM...
LONG TERM...
AVIATION...JDR
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
751 AM EDT SAT SEP 1 2012
.SYNOPSIS...
A WEAK COLD FRONT ALONG THE SOUTH SHORE OF LAKE ERIE IS EXPECTED
TO MOVE SOUTH TO CENTRAL OHIO LATER TODAY AND THEN STALL. THE
REMNANTS OF ISAAC OVER MISSOURI THIS MORNING WILL MOVE SLOWLY EAST
ALONG THE FRONT AND ACROSS THE UPPER OHIO VALLEY ON MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS EXPECTED SOME SHOWERS AND STORMS HAVE BEGUN TO DEVELOP WEST OF
KFDY. THIS ACTIVITY SHOULD MOVE INTO THE WEST END OF THE AREA
SHORTLY. OTHER STORMS ARE EXPECTED TO DEVELOP AND MOVE ACROSS THE
SW 1/3 OF THE AREA THIS MORNING. HAVE DECIDED TO USE SCATTERED
WORDING FOR THAT AREA. LATEST HRRR SHOWING WIDESPREAD PRECIP SOUTH
OF A LINE FROM KTOL TO KYNG BY LATE THIS AFTERNOON.
PREVIOUS...THE COLD FRONT APPEARS TO BE HAVING A TOUGH TIME MAKING IT SOUTH
OF LAKE ERIE. DEWPOINTS HAVE SURGED INTO THE UPPER 60S AND LOWER
70S EVEN AS FAR EAST AS KERI. REGIONAL RADAR IS STARTING TO SHOW
SOME WEAK RETURNS JUST SOUTH OF THE AREA. THE LATEST GUIDANCE
INCLUDING THE HRRR SHOWS PRECIP DEVELOPING OVER THE SW 1/3 OF THE
AREA THIS MORNING AND CONTINUING INTO THE AFTERNOON. AM A LITTLE
CONCERNED THAT THE FRONT WILL NOT MAKE IT AS FAR SOUTH AS FORECAST
AND PRECIP WILL SPREAD FURTHER NORTH THAN EXPECTED. HAVE BUMPED
PRECIP CHANCES UP TO LIKELY IN THE FAR SOUTH AND ALL BUT THE FAR
NE CORNER OF OH AND NW PA WILL GET A PRECIP MENTION TODAY. PWAT
VALUES ARE EXPECTED TO CLIMB ABOVE TWO INCHES BY 00Z. CURRENTLY
NOT MUCH THUNDER BUT CANNOT RULE A FEW RUMBLES LATER TODAY. CLOUDS
SHOULD BE PRETTY THICK TODAY WHICH WILL HOLD TEMPS DOWN ABOUT 10
DEGREES FROM FRIDAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
ONLY MINOR CHANCES TO THE SHORT TERM PERIOD PERIOD THIS MORNING.
MODELS SIMILAR IN TRACKING WHAT`S LEFT OF ISAAC ACROSS THE REGION
ON MONDAY. EXPECT MOISTURE TO SURGE NORTH INTO THE AREA AHEAD OF
THE LOW. PWAT VALUES WILL BE AT OR ABOVE 2 INCHES THE NEXT SEVERAL
DAYS SO THE POTENTIAL EXISTS FOR LOCALLY HEAVY RAINFALL. ABOUT THE
SW 1/2 OF THE AREA CAN EXPECT BETWEEN 1 AND 2 INCHES OF RAINFALL
WITH LOCALLY HEAVIER AMOUNTS POSSIBLE WHERE THE STRONGER BANDS
PERSIST. PRECIP TOTALS WILL DROP OFF QUICKLY TO THE NE. GIVEN
RECENT DRY SPELL AND LOW WATER LEVELS SEE NO NEED FOR ANY FLOOD
HEADLINES. THE PRECIP MAY DROP OFF SOME SUNDAY NIGHT BUT BY
DAYBREAK MONDAY WILL AGAIN NEED LIKELY WORDING ALL AREAS. WILL
CONTINUE TO MENTION THUNDER AS WELL GIVEN UNSTABLE AIRMASS. THE
SURFACE LOW WILL BE NE OF THE AREA BY DAYBREAK TUESDAY AND EXPECT
PRECIP TO QUICKLY DIMINISH FROM WEST TO THE EAST DURING THE DAY.
WEAK COLD AIR ADVECTION BEHIND THE LOW MAY BE ENOUGH TO KICK OFF A
FEW LIGHT SHOWERS INTO TUESDAY NIGHT. HAVE STAYED CLOSE TO GUIDANCE
TEMPS AGAIN TODAY.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AN UPPER LEVEL TROUGH OVER CENTRAL CANADA WILL PUSH EAST ACROSS THE
GREAT LAKES REGION FROM WEDNESDAY INTO THURSDAY. SOUTHERLY FLOW
AHEAD OF THIS FEATURE ON WEDNESDAY WILL HELP TEMPERATURES WARM INTO
THE MID AND UPPER 80S. WILL HOLD ONTO A LOW CHANCE OF
SHOWERS/THUNDERSTORMS AHEAD OF THE TROUGH ACROSS NW OHIO ON
WEDNESDAY...EXPANDING EAST ACROSS THE FORECAST AREA ON THURSDAY. A
COLD FRONT PUSHES SOUTH ACROSS THE AREA ON THURSDAY NIGHT WITH DRY
NORTHWESTERLY FLOW AND BUILDING HIGH PRESSURE FOR THE END OF THE
WEEK. TEMPERATURES WILL DROP BACK TO NEAR OR BELOW NORMAL VALUES.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
MOISTURE ASSOCIATED WITH THE REMNANTS OF ISAAC WILL CONTINUE TO
INCREASE FROM THE SOUTHWEST TODAY. A LEADING BAND OF SHOWERS WILL
CONTINUE TO IMPACT FDY OVER THE NEXT HOUR OR SO BEFORE WEAKENING
AS IT APPROACHES MFD. ADDITIONAL BANDS OF SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO APPROACH FDY/TOL/MFD THIS AFTERNOON
WITH A MOIST AND UNSTABLE AIRMASS IN PLACE WITH THE MOST LIKELY
TIMING BETWEEN 18-22. ANY THUNDERSTORMS THAT IMPACT THE AIRPORTS
THIS AFTERNOON WILL BE CAPABLE OF PRODUCING HEAVY RAINFALL. THERE
IS A LESSER CHANCE OF CONVECTION DEVELOPING FURTHER EAST AS DRIER
AIR TRIES TO PUSH SOUTH BEHIND A WEAK FRONT. SOME DECREASE IN THE
COVERAGE OF SHOWERS AND THUNDERSTORMS IS EXPECTED OVERNIGHT BEFORE
THE DEEPER MOISTURE APPROACHES ON SUNDAY. HIGH LOW LEVEL MOISTURE
MAY RESULT IN MVFR VISIBILITIES AFTER 06Z TONIGHT.
.OUTLOOK...NON VFR POSSIBLE SUNDAY THROUGH TUESDAY FROM THE MOISTURE
ASSOCIATED WITH THE REMNANTS OF ISAAC AND AN APPROACHING COLD
FRONT.
&&
.MARINE...
EASTERLY WINDS WILL CONTINUE ON LAKE ERIE THROUGH THE LABOR DAY
WEEKEND AS LOW PRESSURE ASSOCIATED WITH THE REMNANTS OF ISAAC SLOWLY
MOVES EAST ACROSS THE OHIO VALLY. WINDS AND WAVES WILL BE RELATIVELY
LIGHT THROUGH THE PERIOD WITH CHANCES OF RAIN INCREASING THROUGH
MONDAY. SCATTERED SHOWERS OR THUNDERSTORMS WILL BE CONFINED TO AREAS
FROM CLEVELAND WESTWARD TODAY...EXPANDING EAST ACROSS THE LAKE ON
SUNDAY AND BECOMING MORE WIDESPREAD ON MONDAY. ANY SHOWERS OR
THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE VERY HEAVY
RAINFALL.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...KUBINA
SHORT TERM...KUBINA
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
628 AM EDT SAT SEP 1 2012
.SYNOPSIS...
A WEAK COLD FRONT ALONG THE SOUTH SHORE OF LAKE ERIE IS EXPECTED
TO MOVE SOUTH TO CENTRAL OHIO LATER TODAY AND THEN STALL. THE
REMNANTS OF ISAAC OVER MISSOURI THIS MORNING WILL MOVE SLOWLY EAST
ALONG THE FRONT AND ACROSS THE UPPER OHIO VALLEY ON MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS EXPECTED SOME SHOWERS AND STORMS HAVE BEGUN TO DEVELOP WEST OF
KFDY. THIS ACTIVITY SHOULD MOVE INTO THE WEST END OF THE AREA
SHORTLY. OTHER STORMS ARE EXPECTED TO DEVELOP AND MOVE ACROSS THE
SW 1/3 OF THE AREA THIS MORNING. HAVE DECIDED TO USE SCATTERED
WORDING FOR THAT AREA. LATEST HRRR SHOWING WIDESPREAD PRECIP SOUTH
OF A LINE FROM KTOL TO KYNG BY LATE THIS AFTERNOON.
PREVIOUS...THE COLD FRONT APPEARS TO BE HAVING A TOUGH TIME MAKING IT SOUTH
OF LAKE ERIE. DEWPOINTS HAVE SURGED INTO THE UPPER 60S AND LOWER
70S EVEN AS FAR EAST AS KERI. REGIONAL RADAR IS STARTING TO SHOW
SOME WEAK RETURNS JUST SOUTH OF THE AREA. THE LATEST GUIDANCE
INCLUDING THE HRRR SHOWS PRECIP DEVELOPING OVER THE SW 1/3 OF THE
AREA THIS MORNING AND CONTINUING INTO THE AFTERNOON. AM A LITTLE
CONCERNED THAT THE FRONT WILL NOT MAKE IT AS FAR SOUTH AS FORECAST
AND PRECIP WILL SPREAD FURTHER NORTH THAN EXPECTED. HAVE BUMPED
PRECIP CHANCES UP TO LIKELY IN THE FAR SOUTH AND ALL BUT THE FAR
NE CORNER OF OH AND NW PA WILL GET A PRECIP MENTION TODAY. PWAT
VALUES ARE EXPECTED TO CLIMB ABOVE TWO INCHES BY 00Z. CURRENTLY
NOT MUCH THUNDER BUT CANNOT RULE A FEW RUMBLES LATER TODAY. CLOUDS
SHOULD BE PRETTY THICK TODAY WHICH WILL HOLD TEMPS DOWN ABOUT 10
DEGREES FROM FRIDAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
ONLY MINOR CHANCES TO THE SHORT TERM PERIOD PERIOD THIS MORNING.
MODELS SIMILAR IN TRACKING WHAT`S LEFT OF ISAAC ACROSS THE REGION
ON MONDAY. EXPECT MOISTURE TO SURGE NORTH INTO THE AREA AHEAD OF
THE LOW. PWAT VALUES WILL BE AT OR ABOVE 2 INCHES THE NEXT SEVERAL
DAYS SO THE POTENTIAL EXISTS FOR LOCALLY HEAVY RAINFALL. ABOUT THE
SW 1/2 OF THE AREA CAN EXPECT BETWEEN 1 AND 2 INCHES OF RAINFALL
WITH LOCALLY HEAVIER AMOUNTS POSSIBLE WHERE THE STRONGER BANDS
PERSIST. PRECIP TOTALS WILL DROP OFF QUICKLY TO THE NE. GIVEN
RECENT DRY SPELL AND LOW WATER LEVELS SEE NO NEED FOR ANY FLOOD
HEADLINES. THE PRECIP MAY DROP OFF SOME SUNDAY NIGHT BUT BY
DAYBREAK MONDAY WILL AGAIN NEED LIKELY WORDING ALL AREAS. WILL
CONTINUE TO MENTION THUNDER AS WELL GIVEN UNSTABLE AIRMASS. THE
SURFACE LOW WILL BE NE OF THE AREA BY DAYBREAK TUESDAY AND EXPECT
PRECIP TO QUICKLY DIMINISH FROM WEST TO THE EAST DURING THE DAY.
WEAK COLD AIR ADVECTION BEHIND THE LOW MAY BE ENOUGH TO KICK OFF A
FEW LIGHT SHOWERS INTO TUESDAY NIGHT. HAVE STAYED CLOSE TO GUIDANCE
TEMPS AGAIN TODAY.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AN UPPER LEVEL TROUGH OVER CENTRAL CANADA WILL PUSH EAST ACROSS THE
GREAT LAKES REGION FROM WEDNESDAY INTO THURSDAY. SOUTHERLY FLOW
AHEAD OF THIS FEATURE ON WEDNESDAY WILL HELP TEMPERATURES WARM INTO
THE MID AND UPPER 80S. WILL HOLD ONTO A LOW CHANCE OF
SHOWERS/THUNDERSTORMS AHEAD OF THE TROUGH ACROSS NW OHIO ON
WEDNESDAY...EXPANDING EAST ACROSS THE FORECAST AREA ON THURSDAY. A
COLD FRONT PUSHES SOUTH ACROSS THE AREA ON THURSDAY NIGHT WITH DRY
NORTHWESTERLY FLOW AND BUILDING HIGH PRESSURE FOR THE END OF THE
WEEK. TEMPERATURES WILL DROP BACK TO NEAR OR BELOW NORMAL VALUES.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
A COLD FRONT WILL PUSH SOUTH ACROSS LAKE ERIE THROUGH 09Z WITH WINDS
SHIFTING TO THE NORTH FOR AIRPORTS NEAR THE LAKE. MEANWHILE MOISTURE
ASSOCIATED WITH THE REMNANTS OF ISAAC CONTINUE TO SPREAD NORTH INTO
OHIO. SOME BR IS POSSIBLE ALONG THE FRONT AS IT STALLS OVER NORTHERN
OHIO BETWEEN 09-13Z WITH VISIBILITIES ONLY DROPPING TO AROUND 4
MILES. OTHERWISE CHANCES OF SHOWERS AND THUNDERSTORMS WILL INCREASE
ACROSS WESTERN OHIO THROUGH THE AFTERNOON AND WILL CONTINUE TO CARRY
VCTS AS ENERGY SPIRALS AWAY FROM THE REMNANTS OF THE TROPICAL
SYSTEM. UNCERTAINTY REMAINS WITH RESPECT TO TIMING THUNDERSTORMS BUT
THINK CHANCES OF BRIEF HEAVY RAINFALL ARE PRETTY GOOD LATE THIS
AFTERNOON INTO THIS EVENING. DRIER AIR BEHIND THE FRONT SHOULD LIMIT
CHANCES OF PRECIPITATION ACROSS NE OHIO/NW PA WITH THE OVERALL
COVERAGE OF SHOWERS DECREASING WITH THE LOSS OF DIURNAL HEATING
AFTER 00Z. MVFR VISIBILITIES WILL BE POSSIBLE AGAIN AFTER 06Z WITH
HIGH LOW LEVEL MOISTURE ACROSS THE AREA.
.OUTLOOK...NON VFR POSSIBLE SUNDAY THROUGH TUESDAY FROM THE MOISTURE
ASSOCIATED WITH THE REMNANTS OF ISAAC AND AN APPROACHING COLD
FRONT.
&&
.MARINE...
EASTERLY WINDS WILL CONTINUE ON LAKE ERIE THROUGH THE LABOR DAY
WEEKEND AS LOW PRESSURE ASSOCIATED WITH THE REMNANTS OF ISAAC SLOWLY
MOVES EAST ACROSS THE OHIO VALLY. WINDS AND WAVES WILL BE RELATIVELY
LIGHT THROUGH THE PERIOD WITH CHANCES OF RAIN INCREASING THROUGH
MONDAY. SCATTERED SHOWERS OR THUNDERSTORMS WILL BE CONFINED TO AREAS
FROM CLEVELAND WESTWARD TODAY...EXPANDING EAST ACROSS THE LAKE ON
SUNDAY AND BECOMING MORE WIDESPREAD ON MONDAY. ANY SHOWERS OR
THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE VERY HEAVY
RAINFALL.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...KUBINA
SHORT TERM...KUBINA
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
350 AM EDT SAT SEP 1 2012
.SYNOPSIS...
A WEAK COLD FRONT ALONG THE SOUTH SHORE OF LAKE ERIE IS EXPECTED
TO MOVE SOUTH TO CENTRAL OHIO LATER TODAY AND THEN STALL. THE
REMNANTS OF ISAAC OVER MISSOURI THIS MORNING WILL MOVE SLOWLY EAST
ALONG THE FRONT AND ACROSS THE UPPER OHIO VALLEY ON MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE COLD FRONT APPEARS TO BE HAVING A TOUGH TIME MAKING IT SOUTH
OF LAKE ERIE. DEWPOINTS HAVE SURGED INTO THE UPPER 60S AND LOWER
70S EVEN AS FAR EAST AS KERI. REGIONAL RADAR IS STARTING TO SHOW
SOME WEAK RETURNS JUST SOUTH OF THE AREA. THE LATEST GUIDANCE
INCLUDING THE HRRR SHOWS PRECIP DEVELOPING OVER THE SW 1/3 OF THE
AREA THIS MORNING AND CONTINUING INTO THE AFTERNOON. AM A LITTLE
CONCERNED THAT THE FRONT WILL NOT MAKE IT AS FAR SOUTH AS FORECAST
AND PRECIP WILL SPREAD FURTHER NORTH THAN EXPECTED. HAVE BUMPED
PRECIP CHANCES UP TO LIKELY IN THE FAR SOUTH AND ALL BUT THE FAR
NE CORNER OF OH AND NW PA WILL GET A PRECIP MENTION TODAY. PWAT
VALUES ARE EXPECTED TO CLIMB ABOVE TWO INCHES BY 00Z. CURRENTLY
NOT MUCH THUNDER BUT CANNOT RULE A FEW RUMBLES LATER TODAY. CLOUDS
SHOULD BE PRETTY THICK TODAY WHICH WILL HOLD TEMPS DOWN ABOUT 10
DEGREES FROM FRIDAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
ONLY MINOR CHANCES TO THE SHORT TERM PERIOD PERIOD THIS MORNING.
MODELS SIMILAR IN TRACKING WHAT`S LEFT OF ISAAC ACROSS THE REGION
ON MONDAY. EXPECT MOISTURE TO SURGE NORTH INTO THE AREA AHEAD OF
THE LOW. PWAT VALUES WILL BE AT OR ABOVE 2 INCHES THE NEXT SEVERAL
DAYS SO THE POTENTIAL EXISTS FOR LOCALLY HEAVY RAINFALL. ABOUT THE
SW 1/2 OF THE AREA CAN EXPECT BETWEEN 1 AND 2 INCHES OF RAINFALL
WITH LOCALLY HEAVIER AMOUNTS POSSIBLE WHERE THE STRONGER BANDS
PERSIST. PRECIP TOTALS WILL DROP OFF QUICKLY TO THE NE. GIVEN
RECENT DRY SPELL AND LOW WATER LEVELS SEE NO NEED FOR ANY FLOOD
HEADLINES. THE PRECIP MAY DROP OFF SOME SUNDAY NIGHT BUT BY
DAYBREAK MONDAY WILL AGAIN NEED LIKELY WORDING ALL AREAS. WILL
CONTINUE TO MENTION THUNDER AS WELL GIVEN UNSTABLE AIRMASS. THE
SURFACE LOW WILL BE NE OF THE AREA BY DAYBREAK TUESDAY AND EXPECT
PRECIP TO QUICKLY DIMINISH FROM WEST TO THE EAST DURING THE DAY.
WEAK COLD AIR ADVECTION BEHIND THE LOW MAY BE ENOUGH TO KICK OFF A
FEW LIGHT SHOWERS INTO TUESDAY NIGHT. HAVE STAYED CLOSE TO GUIDANCE
TEMPS AGAIN TODAY.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AN UPPER LEVEL TROUGH OVER CENTRAL CANADA WILL PUSH EAST ACROSS THE
GREAT LAKES REGION FROM WEDNESDAY INTO THURSDAY. SOUTHERLY FLOW
AHEAD OF THIS FEATURE ON WEDNESDAY WILL HELP TEMPERATURES WARM INTO
THE MID AND UPPER 80S. WILL HOLD ONTO A LOW CHANCE OF
SHOWERS/THUNDERSTORMS AHEAD OF THE TROUGH ACROSS NW OHIO ON
WEDNESDAY...EXPANDING EAST ACROSS THE FORECAST AREA ON THURSDAY. A
COLD FRONT PUSHES SOUTH ACROSS THE AREA ON THURSDAY NIGHT WITH DRY
NORTHWESTERLY FLOW AND BUILDING HIGH PRESSURE FOR THE END OF THE
WEEK. TEMPERATURES WILL DROP BACK TO NEAR OR BELOW NORMAL VALUES.
&&
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
A COLD FRONT WILL PUSH SOUTH ACROSS LAKE ERIE THROUGH 09Z WITH WINDS
SHIFTING TO THE NORTH FOR AIRPORTS NEAR THE LAKE. MEANWHILE MOISTURE
ASSOCIATED WITH THE REMNANTS OF ISAAC CONTINUE TO SPREAD NORTH INTO
OHIO. SOME BR IS POSSIBLE ALONG THE FRONT AS IT STALLS OVER NORTHERN
OHIO BETWEEN 09-13Z WITH VISIBILITIES ONLY DROPPING TO AROUND 4
MILES. OTHERWISE CHANCES OF SHOWERS AND THUNDERSTORMS WILL INCREASE
ACROSS WESTERN OHIO THROUGH THE AFTERNOON AND WILL CONTINUE TO CARRY
VCTS AS ENERGY SPIRALS AWAY FROM THE REMNANTS OF THE TROPICAL
SYSTEM. UNCERTAINTY REMAINS WITH RESPECT TO TIMING THUNDERSTORMS BUT
THINK CHANCES OF BRIEF HEAVY RAINFALL ARE PRETTY GOOD LATE THIS
AFTERNOON INTO THIS EVENING. DRIER AIR BEHIND THE FRONT SHOULD LIMIT
CHANCES OF PRECIPITATION ACROSS NE OHIO/NW PA WITH THE OVERALL
COVERAGE OF SHOWERS DECREASING WITH THE LOSS OF DIURNAL HEATING
AFTER 00Z. MVFR VISIBILITIES WILL BE POSSIBLE AGAIN AFTER 06Z WITH
HIGH LOW LEVEL MOISTURE ACROSS THE AREA.
.OUTLOOK...NON VFR POSSIBLE SUNDAY THROUGH TUESDAY FROM THE MOISTURE
ASSOCIATED WITH THE REMNANTS OF ISAAC AND AN APPROACHING COLD
FRONT.
&&
.MARINE...
EASTERLY WINDS WILL CONTINUE ON LAKE ERIE THROUGH THE LABOR DAY
WEEKEND AS LOW PRESSURE ASSOCIATED WITH THE REMNANTS OF ISAAC SLOWLY
MOVES EAST ACROSS THE OHIO VALLY. WINDS AND WAVES WILL BE RELATIVELY
LIGHT THROUGH THE PERIOD WITH CHANCES OF RAIN INCREASING THROUGH
MONDAY. SCATTERED SHOWERS OR THUNDERSTORMS WILL BE CONFINED TO AREAS
FROM CLEVELAND WESTWARD TODAY...EXPANDING EAST ACROSS THE LAKE ON
SUNDAY AND BECOMING MORE WIDESPREAD ON MONDAY. ANY SHOWERS OR
THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE VERY HEAVY
RAINFALL.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...KUBINA
SHORT TERM...KUBINA
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
824 PM EDT SUN SEP 2 2012
.SYNOPSIS...
A STATIONARY FRONT WILL REMAIN DRAPED ACROSS SOUTHERN PENNSYLVANIA
TONIGHT. THE MOISTURE ASSOCIATED WITH THE REMNANTS OF HURRICANE
ISAAC WILL SLIDE EASTWARD ALONG THIS FRONTAL BOUNDARY...AND MOVE
ACROSS THE REGION EARLY THIS WEEK. THE DEEP MOISTURE SHOULD BE
EAST OF THE AREA BY LATE WEDNESDAY. WEAK HIGH PRESSURE WILL
BUILD INTO THE AREA FOR THE LATTER PART OF THE WEEK. A DIGGING
UPPER TROUGH WILL FORM ACROSS THE REGION BY LATE NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
SHOWERS ARE EXTREMELY SPARSE...BUT TWO HOT SPOTS EXIST - BOTH ARE
GENERALLY RIGHT ALONG A LINE RUNNING FROM EBENSBURG...THROUGH THE
SC MTS AND INTO SRN YORK COUNTY. THE CLUSTER OF SHOWERS - NOT
THUNDER YET - IS MAKING MO AND PERHAPS HEAVY RAIN AND COULD BE
BACK BUILDING PER LATEST RADAR TRENDS. WILL MENTION HEAVY RAIN
WITH TS POSSIBLE THIS EVENING ACROSS THE SOUTH...AS PINPOINTING
WHERE THE SHOWERS WILL POP UP AND/OR BE PERSISTENT IS VERY
DIFFICULT. HRRR AND RUC BOTH SUPPORT A SLIGHT DIMINISHING TREND
THIS EVENING ON THE WHOLE...BUT PERSISTENT CONVERGENCE OVER THE
LOWER SUSQ REGION AND PLACE QPF THERE. LATER TONIGHT...MOST MDLS
BRING IN ADDITIONAL MOISTURE FROM THE SE AS THE HIGH OVER THE NERN
STATES STARTS TO MOVE SOUTH AND STRENGTHEN A BIT. SO WILL KEEP
POPS IN THE MID-HIGH CHC RANGE FOR THE SERN HALF OF THE AREA
TONIGHT.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
SOME CONCERN ABOUT HEAVIER RAIN LATER MONDAY...BUT DID NOT ISSUE
ANY FLOOD PRODUCTS AT THIS POINT.
A NEAR PERSISTENCE FORECAST EXPECTED ON MONDAY WITH A SIMILAR
SCENARIO PLAYING OUT. EXPECT SHRA AND A FEW TSRA BECOMING NUMEROUS
BY AFTN...ESPECIALLY ACROSS THE SOUTHERN THIRD OF CENTRAL
PA...RESULTING FROM DIURNAL HEATING AND APPROACH OF UPPER TROF.
MDLS INDICATE QUASI-STATIONARY FRONT WILL PUSH A BIT FURTHER NORTH
ON MONDAY...SPREADING THE LIKELIHOOD OF RAINFALL TO THE N TIER.
BEST OPPORTUNITY FOR A FEW THIN SPOTS IN THE OVERCAST WILL BE
ALONG AND WEST OF THE ALLEGHENY FRONT. MDL DATA INDICATES THIS
AREA ALSO LIKELY TO REALIZE THE HIGHEST CAPES AND EXPERIENCE THE
BEST CHC OF PM THUNDER.
OVERCAST SKIES WILL LIMIT TEMPS TO THE 70S IN MOST SPOTS MONDAY.
HOWEVER...WITH DWPTS CLOSE TO 70F...IT WILL CERTAINLY FEEL WARMER.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
REMAINS OF ISAAC WERE MOVING ALONG. GFS SLIGHTLY FASTER THAN
OTHER MODELS.
NOW THE REMAINS OF ISAAC JUST SW OF LAKE MI ARE NEARLY
STATIONARY.
ANYWAY...EITHER WAY...GIVEN STALLED FRONTAL BOUNDARY...HIGH PW
VAULES...THINK THERE IS SUPPORT FOR HEAVY RAIN ANYTIME PRIOR TO
WED AFT. THUS DID UP POPS SOME. AT THIS POINT...DID NOT SEE A NEED
FOR A FLOOD WATCH ETC.
DID UP TEMPS SOME AT NIGHT...GIVEN CLD COVER AND TYPE OF
AIRMASS IN PLACE.
FOR THU...WENT WITH MAINLY A DRY FCST...EXCEPT FOR FAR
NW...WITH COLD FRONT PUSHING SE.
WENT WITH A DRY FCST FOR FRIDAY.
GOOD CHANCE FOR SHOWERS AND THUNDERSTORMS BY LATE NEXT
SATURDAY...A LOT OF SPREAD IN MODEL SOLUTIONS...BUT HINTS
THAT SYSTEM HAS A NEGATIVE TILT.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
A STATIONARY FRONT REMAINS TO OUR SOUTH INTO MONDAY. MAINLY VFR
CONDITIONS WILL CONTINUE THROUGH THE FIRST HALF OF THE
EVENING. SCATTERED SHOWERS HAVE DEVELOPED DUE TO STRONG MOISTURE
FLUX AT THE LOWER LEVELS. ANY SHOWERS ARE SHALLOW...THOUGH ARE
EFFICIENT RAINERS. LOW STRATOCU AND RAIN ARE CURRENTLY ALLOWING
FOR MVFR CIGS AND VSBYS AT AOO...IPT AND LNS. EXPECT MORE WIDESPREAD
MVFR/IFR CONDITIONS TO DEVELOP LATE THIS EVENING...INTO TOMORROW
MORNING. MOISTURE WILL CONTINUE TO INCREASE AHEAD OF THE APPROACHING
REMNANTS OF ISAAC. THIS WILL BRING LOWER CIGS /ESP AT NIGHT/ AND
VERY HIGH PROB OF SHOWERS AND THUNDERSTORMS LATE MONDAY INTO TUE
NIGHT. WITH STRONG BOUNDARY LAYER MOISTURE...AND MOIST LOW
LEVELS...EXPECT MVFR STRATOCU THROUGH 00Z TUESDAY.
OUTLOOK...
MON...SHOWERS BECOMING MORE NUMEROUS WITH ISO AFT TSRA...ESP
SOUTH. LOW CIGS LIKELY...ESPECIALLY LATE AND MON NIGHT.
TUE...SHOWERS WITH SCT TSTMS. PERIODS OF LOW CIGS LIKELY.
WED...SCT SHOWERS AND ISO AFT TSRA. PERIODS OF LOW CIGS POSS.
THU...IMPROVING CONDITIONS...WITH SCT SHOWERS POSSIBLE ACROSS
THE NW.
FRI...MAINLY VFR CONDITIONS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MARTIN
NEAR TERM...DANGELO
SHORT TERM...DEVOIR/MARTIN
LONG TERM...MARTIN
AVIATION...DEVOIR/CERU
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1034 PM CDT SUN SEP 2 2012
.DISCUSSION...
FRONTAL BOUNDARY PRESENTLY LOCATED IN A LINE ROUGHLY FROM BROOKINGS
TO YANKTON LATE THIS EVENING. MODELS HAVE HANDLED CONVECTION VERY
POORLY THIS EVENING...WITH CONVECTION FAILING TO MATERIALIZE WITH
STRONG CAPPING IN PLACE. ONLY THE HRRR CAUGHT ON TO THIS...AND WILL
GENERALLY FOLLOW THIS MODEL SOLUTION WITH LITTLE ADDITIONAL
CONVECTION TONIGHT. WHILE CANNOT COMPLETELY RULE OUT AN ISOLATED
STORM THROUGH THE REMAINDER OF THE NIGHT WITH WEAK THETA E ADVECTION
IN OUR FAR SOUTHEAST OUT AHEAD OF AFOREMENTIONED BOUNDARY...LOWERED
POPS FOR THE REMAINDER OF THE NIGHT. UPDATES OUT.
&&
.PREV DISCUSSION.../ISSUED AT 353 PM CDT/
IT IS NO SURPRISE THAT WE ARE WAITING UNTIL LATE IN THE DAY FOR
THUNDERSTORM DEVELOPMENT. STRENGTH OF HEATING AND DECENT INFLOW
SUGGESTS WE WILL STILL GET IT WITH THE FRONTAL BOUNDARY ACTING AS A
FOCUS. HOWEVER DEVELOPMENT SHOULD BE LIMITED ESPECIALLY SINCE THE
FRONT IS DOING A PRETTY GOOD JOB OF MOVING ACROSS THE AREA BEFORE IT
WEAKENS AND SLOWS. MINIMAL SEVERE POTENTIAL STILL SEEMS AVAILABLE
WITH THE LIMITED DEVELOPMENT AS ANY STORMS THAT DEVELOP WILL HAVE
THAT DECENT INFLOW AND SHEAR. BROAD SCALE LIFT IS NOT TOO GOOD
THOUGH. WILL MENTION THE EVENING CHANCE MAINLY EASTERN HALF OF THE
FORECAST AREA MINUS THE SOUTHEAST CORNER...THEN TAIL OFF A SLIGHT
CHANCE IN THE SOUTH LATE AS BOUNDARY WEAKENS AND SLOWS...THOUGH SOME
INSTABILITY WILL BE AVAILABLE. LOW TEMPERATURES SHOULD NOT BE FAR
FROM GUIDANCE WITH WARM LOWS SOUTHEAST IN THE ABSENCE OF ANY REAL
COOLER AND DRIER PENETRATION EVEN LATE...IN FACT THERE THE AIR WILL
MOISTEN UP AT LOW LEVELS. WINDS SHOULD STEADILY DROP OFF.
LABOR DAY SHOULD SEE JUST A LITTLE LEFTOVER DRYING EAST WHILE
MOISTURE AND INSTABILITY BEGIN A FAIRLY HEALTHY RETURN WEST...WHICH
IS OVER MOST OF SOUTHEAST SD. CHANCE OF STORMS WILL INCREASE WEST
DURING THE DAY AND SHOULD BE MOSTLY ABSENT EAST...EXCEPT FOR A
SLIGHT CHANCE CONTINUING FROM SIOUX CITY AREA EAST AS DRYING AND
STABILIZING ARE ALMOST NIL. HIGH TEMPERATURES SHOULD BE MOSTLY UPPER
80S EAST TO LOWER 90S WEST...THIS IS A LITTLE WARMER THAN GUIDANCE
EAST AS HEATING SHOULD BE A FACTOR THERE. A RELATIVELY LIGHT
SOUTHEAST BREEZE SHOULD DEVELOP DURING THE DAY.
SLOPPY PATTERN IN QUASI-ZONAL FLOW MONDAY NIGHT THROUGH TUESDAY AS
NORTHERN STREAM WAVE DIGS INTO BASE OF UPPER LOW ALREADY IN PLACE
OVER CENTRAL CANADA. MODELS SHOW SUBTLE WAVES SLIDE EAST THROUGH
THIS WESTERLY FLOW ALOFT...BUT WEAK SURFACE PATTERN PROVIDES LITTLE
IN THE WAY OF A FOCUS FOR ANY ORGANIZED CONVECTION...THOUGH APPEARS
WEAK LOW NEAR THE MIDDLE JAMES VALLEY COULD PROVIDE A LITTLE BETTER
CHANCE ACROSS THE NORTHWEST HALF OF OUR CWA MONDAY EVENING. MODELS
ALSO SHOWING A LITTLE STRONGER WAVE MOVING THROUGH CENTRAL PLAINS
WITH LOW LEVEL JET FOCUSING THROUGH SOUTHEAST NEBRASKA/SOUTHWEST
IOWA. ANY DEVELOPMENT WITH THIS FEATURE COULD DRIFT INTO OUR FAR
SOUTHEAST CORNER OVERNIGHT...BUT BETTER CHANCE LOOKS TO REMAIN SOUTH
OF THIS FORECAST AREA. ANY OVERNIGHT ACTIVITY SHOULD EXIT THE CWA BY
DAYBREAK.
WILL BRING POPS BACK INTO THE SOUTHWEST CWA/MISSOURI VALLEY TUESDAY
AFTERNOON AS 850MB WARM FRONT LIFTS NORTH AHEAD OF THE STRONGER
UPPER WAVE SWINGING DOWN INTO THE DAKOTAS/MINNESOTA TUESDAY NIGHT.
TUESDAY EVENING LOOKS TO BE BEST CHANCE FOR PRECIPITATION...AS MORE
POTENT COLD FRONT AND UPPER TROUGH PUSH THROUGH THE REGION. PRECIP
AMOUNTS LIKELY TO BE LIMITED BY SPEED OF MOVEMENT...AS FRONT IS
FORECAST TO MOVE EAST RATHER QUICKLY. HOWEVER SEEMS MOST AREAS EAST
OF THE JAMES SHOULD HAVE DECENT SHOT AT SEEING AT LEAST MEASURABLE
PRECIP AND HAVE BUMPED POPS TO HIGH CHANCE/LIKELY FOR LATE EVENING
AND INTO THE EARLY MORNING. THIS FRONT SHOULD BRING AN END THE ABOVE
NORMAL TEMPERATURES FOR A WHILE...WITH NORMAL-BELOW NORMAL READINGS
SETTLING IN WEDNESDAY THROUGH THE UPCOMING WEEKEND.
ANY TUESDAY NIGHT STORMS SHOULD BE EAST OF THE CWA BY WEDNESDAY...
LEAVING COMFORTABLE LATE SUMMER TEMPERATURES ACCOMPANIED BY MIXY
NORTHWEST WINDS THROUGH THE AFTERNOON. WINDS SHOULD SETTLE DOWN
QUICKLY WEDNESDAY EVENING AS SURFACE HIGH MOVES IN. LONG RANGE
MODELS IN DECENT AGREEMENT BRINGING A MID LEVEL WAVE ACROSS THE
REGION THURSDAY/THURSDAY NIGHT...WITH BROAD TROUGH KEEPING A CHANCE
OF SHOWERS AND A FEW STORMS LINGERING INTO FRIDAY. REINFORCING COLD
SHOT ASSOCIATED WITH THIS WAVE WILL PUSH HIGHS INTO THE LOWER 70S
MOST AREAS ON FRIDAY...WITH GRADUAL TEMPERATURE RECOVERY BUILDING
BACK IN FOR WHAT SHOULD BE A DRY AND PLEASANT WEEKEND.
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
VFR CONDITIONS WILL PREVAIL THROUGH MONDAY. AT THIS TIME IT APPEARS
THAT ANY SHOWER OR THUNDERSTORM CHANCES WILL BE ISOLATED ENOUGH AS
TO NOT WARRANT A MENTION IN ANY TAF SITE THROUGH 06Z TUESDAY.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
$$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
920 PM CDT SUN SEP 2 2012
.DISCUSSION...
FRONTAL BOUNDARY PRESENTLY LOCATED IN A LINE ROUGHLY FROM BROOKINGS
TO YANKTON LATE THIS EVENING. MODELS HAVE HANDLED CONVECTION VERY
POORLY THIS EVENING...WITH CONVECTION FAILING TO MATERIALIZE WITH
STRONG CAPPING IN PLACE. ONLY THE HRRR CAUGHT ON TO THIS...AND WILL
GENERALLY FOLLOW THIS MODEL SOLUTION WITH LITTLE ADDITIONAL
CONVECTION TONIGHT. WHILE CANNOT COMPLETELY RULE OUT AN ISOLATED
STORM THROUGH THE REMAINDER OF THE NIGHT WITH WEAK THETA E ADVECTION
IN OUR FAR SOUTHEAST OUT AHEAD OF AFOREMENTIONED BOUNDARY...LOWERED
POPS FOR THE REMAINDER OF THE NIGHT. UPDATES OUT.
&&
.PREV DISCUSSION.../ISSUED AT 353 PM CDT/
IT IS NO SURPRISE THAT WE ARE WAITING UNTIL LATE IN THE DAY FOR
THUNDERSTORM DEVELOPMENT. STRENGTH OF HEATING AND DECENT INFLOW
SUGGESTS WE WILL STILL GET IT WITH THE FRONTAL BOUNDARY ACTING AS A
FOCUS. HOWEVER DEVELOPMENT SHOULD BE LIMITED ESPECIALLY SINCE THE
FRONT IS DOING A PRETTY GOOD JOB OF MOVING ACROSS THE AREA BEFORE IT
WEAKENS AND SLOWS. MINIMAL SEVERE POTENTIAL STILL SEEMS AVAILABLE
WITH THE LIMITED DEVELOPMENT AS ANY STORMS THAT DEVELOP WILL HAVE
THAT DECENT INFLOW AND SHEAR. BROAD SCALE LIFT IS NOT TOO GOOD
THOUGH. WILL MENTION THE EVENING CHANCE MAINLY EASTERN HALF OF THE
FORECAST AREA MINUS THE SOUTHEAST CORNER...THEN TAIL OFF A SLIGHT
CHANCE IN THE SOUTH LATE AS BOUNDARY WEAKENS AND SLOWS...THOUGH SOME
INSTABILITY WILL BE AVAILABLE. LOW TEMPERATURES SHOULD NOT BE FAR
FROM GUIDANCE WITH WARM LOWS SOUTHEAST IN THE ABSENCE OF ANY REAL
COOLER AND DRIER PENETRATION EVEN LATE...IN FACT THERE THE AIR WILL
MOISTEN UP AT LOW LEVELS. WINDS SHOULD STEADILY DROP OFF.
LABOR DAY SHOULD SEE JUST A LITTLE LEFTOVER DRYING EAST WHILE
MOISTURE AND INSTABILITY BEGIN A FAIRLY HEALTHY RETURN WEST...WHICH
IS OVER MOST OF SOUTHEAST SD. CHANCE OF STORMS WILL INCREASE WEST
DURING THE DAY AND SHOULD BE MOSTLY ABSENT EAST...EXCEPT FOR A
SLIGHT CHANCE CONTINUING FROM SIOUX CITY AREA EAST AS DRYING AND
STABILIZING ARE ALMOST NIL. HIGH TEMPERATURES SHOULD BE MOSTLY UPPER
80S EAST TO LOWER 90S WEST...THIS IS A LITTLE WARMER THAN GUIDANCE
EAST AS HEATING SHOULD BE A FACTOR THERE. A RELATIVELY LIGHT
SOUTHEAST BREEZE SHOULD DEVELOP DURING THE DAY.
SLOPPY PATTERN IN QUASI-ZONAL FLOW MONDAY NIGHT THROUGH TUESDAY AS
NORTHERN STREAM WAVE DIGS INTO BASE OF UPPER LOW ALREADY IN PLACE
OVER CENTRAL CANADA. MODELS SHOW SUBTLE WAVES SLIDE EAST THROUGH
THIS WESTERLY FLOW ALOFT...BUT WEAK SURFACE PATTERN PROVIDES LITTLE
IN THE WAY OF A FOCUS FOR ANY ORGANIZED CONVECTION...THOUGH APPEARS
WEAK LOW NEAR THE MIDDLE JAMES VALLEY COULD PROVIDE A LITTLE BETTER
CHANCE ACROSS THE NORTHWEST HALF OF OUR CWA MONDAY EVENING. MODELS
ALSO SHOWING A LITTLE STRONGER WAVE MOVING THROUGH CENTRAL PLAINS
WITH LOW LEVEL JET FOCUSING THROUGH SOUTHEAST NEBRASKA/SOUTHWEST
IOWA. ANY DEVELOPMENT WITH THIS FEATURE COULD DRIFT INTO OUR FAR
SOUTHEAST CORNER OVERNIGHT...BUT BETTER CHANCE LOOKS TO REMAIN SOUTH
OF THIS FORECAST AREA. ANY OVERNIGHT ACTIVITY SHOULD EXIT THE CWA BY
DAYBREAK.
WILL BRING POPS BACK INTO THE SOUTHWEST CWA/MISSOURI VALLEY TUESDAY
AFTERNOON AS 850MB WARM FRONT LIFTS NORTH AHEAD OF THE STRONGER
UPPER WAVE SWINGING DOWN INTO THE DAKOTAS/MINNESOTA TUESDAY NIGHT.
TUESDAY EVENING LOOKS TO BE BEST CHANCE FOR PRECIPITATION...AS MORE
POTENT COLD FRONT AND UPPER TROUGH PUSH THROUGH THE REGION. PRECIP
AMOUNTS LIKELY TO BE LIMITED BY SPEED OF MOVEMENT...AS FRONT IS
FORECAST TO MOVE EAST RATHER QUICKLY. HOWEVER SEEMS MOST AREAS EAST
OF THE JAMES SHOULD HAVE DECENT SHOT AT SEEING AT LEAST MEASURABLE
PRECIP AND HAVE BUMPED POPS TO HIGH CHANCE/LIKELY FOR LATE EVENING
AND INTO THE EARLY MORNING. THIS FRONT SHOULD BRING AN END THE ABOVE
NORMAL TEMPERATURES FOR A WHILE...WITH NORMAL-BELOW NORMAL READINGS
SETTLING IN WEDNESDAY THROUGH THE UPCOMING WEEKEND.
ANY TUESDAY NIGHT STORMS SHOULD BE EAST OF THE CWA BY WEDNESDAY...
LEAVING COMFORTABLE LATE SUMMER TEMPERATURES ACCOMPANIED BY MIXY
NORTHWEST WINDS THROUGH THE AFTERNOON. WINDS SHOULD SETTLE DOWN
QUICKLY WEDNESDAY EVENING AS SURFACE HIGH MOVES IN. LONG RANGE
MODELS IN DECENT AGREEMENT BRINGING A MID LEVEL WAVE ACROSS THE
REGION THURSDAY/THURSDAY NIGHT...WITH BROAD TROUGH KEEPING A CHANCE
OF SHOWERS AND A FEW STORMS LINGERING INTO FRIDAY. REINFORCING COLD
SHOT ASSOCIATED WITH THIS WAVE WILL PUSH HIGHS INTO THE LOWER 70S
MOST AREAS ON FRIDAY...WITH GRADUAL TEMPERATURE RECOVERY BUILDING
BACK IN FOR WHAT SHOULD BE A DRY AND PLEASANT WEEKEND.
&&
.AVIATION.../FOR THE 00Z TAF ISSUANCE/
VFR CONDITIONS WILL PREVAIL THROUGH MONDAY. AT THIS TIME IT APPEARS
THAT ISOLATED TO SCATTERED THUNDERSTORM DEVELOPMENT IN OUR FORECAST
AREA THIS EVENING WILL BE DIFFICULT TO COME BY. CONVECTIVE
TEMPERATURES ARE VERY HIGH WITH STRONG CAPPING CONTINUING TO BE IN
PLACE. THEREFORE AT LEAST FOR NOW...AM GOING TO GO AHEAD AND LEAVE
THE TAF SITES DRY. THE SAME HOLDS FOR LABOR DAY. THUNDERSTORM
CHANCES ARE JUST TOO ISOLATED TO WARRANT A MENTION IN ANY PARTICULAR
TAF SITE.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
$$
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
331 PM CDT SAT SEP 1 2012
.DISCUSSION...19Z SURFACE ANALYSIS CENTERS THE REMNANTS OF ISAAC
JUST NORTH OF COLUMBIA MISSOURI. THERE HAS BEEN A BREAK IN THE
SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE MID SOUTH FROM LATE
THIS MORNING THROUGH MID AFTERNOON AS A DRY SLOT /INDICATED BY
WATER VAPOR SATELLITE TRENDS/ HAS BUILT IN TO ARKANSAS AND MUCH OF
THE MID SOUTH. THUNDERSTORMS ARE ONLY BEGINNING TO DEVELOP ONCE
AGAIN UP ACROSS EXTREME NORTHWEST ARKANSAS IN ASSOCIATION WITH AN
APPROACHING SHORTWAVE ASSOCIATED WITH THE REMNANTS OF ISAAC.
TEMPERATURES AS OF 3 PM CDT ARE IN THE MIDDLE 80S TO LOWER 90S
ACROSS THE FORECAST AREA. STRONG TO SEVERE THUNDERSTORM POTENTIAL
TONIGHT AND CONVECTIVE CHANCES INTO NEXT WEEK ARE THE MAIN
FORECAST CHALLENGES FOR THIS AFTERNOON/S FORECAST ISSUANCE.
.SHORT TERM...(TONIGHT THROUGH TUESDAY)...LATEST SHORT TERM
MODELS...ESPECIALLY THE HRRR AND THE 12Z WRF SUGGEST THE
RELATIVELY RAIN FREE CONDITIONS CURRENTLY OCCURRING ACROSS THE MID
SOUTH WILL COME TO AN END THIS EVENING AS ANOTHER SHORTWAVE
ROTATING AROUND THE REMNANTS OF ISAAC MOVES ACROSS THE LOWER
MISSISSIPPI VALLEY TONIGHT. DAYTIME INSTABILITY /SURFACE BASED
CAPE VALUES AVERAGING BETWEEN 2000-3500 J/KG...LI/S BETWEEN -5 TO
-6/ AND STEEP LOW LEVEL LAPSE RATES HAVE RESULTED IN THE
DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS ACROSS
ARKANSAS...FROM NEAR WALNUT RIDGE BACK THROUGH CENTRAL AND WEST
CENTRAL ARKANSAS. AT THIS TIME BELIEVE THIS ACTIVITY WILL
GRADUALLY INCREASE IN COVERAGE AS IT MOVES ACROSS THE MID SOUTH
TONIGHT...ESPECIALLY ALONG AND NORTH OF I-40. THUS...INCREASED
POPS ACROSS THE ABOVE MENTIONED AREAS. A FEW STRONG TO PERHAPS
ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE TONIGHT AS THIS
SHORTWAVE MOVES THROUGH THE MID SOUTH. DAMAGING WINDS WILL BE THE
MAIN THREAT FOR ANY THUNDERSTORM THAT REACHES SEVERE LIMITS. A
TROPICAL AIR MASS COMBINED WITH PRECIPITABLE WATER VALUES ABOVE 2
INCHES SUGGESTS THE POTENTIAL FOR LOCALIZED FLASH FLOODING FROM
HEAVY RAINFALL WITHIN THUNDERSTORMS.
SHORT TERM MODELS INDICATE THE REMNANTS OF ISAAC WILL GRADUALLY
MOVE EAST SOUTHEAST TO THE OHIO AND TENNESSEE VALLEYS FOR SUNDAY
THROUGH TUESDAY. AS A RESULT...A CONTINUED CHANCE FOR SHOWERS AND
THUNDERSTORMS WILL PERSIST BUT GRADUALLY DECREASE THROUGH THE
REMAINDER OF THE PERIOD. A STRONG THUNDERSTORM OR TWO CONTAINING
HEAVY RAINFALL AND GUSTY WINDS WILL ALSO BE POSSIBLE ON SUNDAY
AFTERNOON.
.LONG TERM...(WEDNESDAY THROUGH SATURDAY)...12Z GFS/ECMWF LONG
RANGE MODELS INDICATE CHANCES FOR SHOWERS AND THUNDERSTORMS WILL
PERSIST ACROSS THE AREA THROUGHOUT THE PERIOD AS ANOTHER COLD
FRONT DROPS INTO THE AREA WEDNESDAY NIGHT INTO THURSDAY NIGHT AND
THEN STALLS OUT ACROSS THE AREA INTO NEXT WEEKEND. KEPT
PRECIPITATION CHANCES ON THE LOW END FOR THE TIME BEING AS THERE
ARE SOME TIMING/COVERAGE DIFFERENCES BETWEEN THE LONG TERM MODEL
SOLUTIONS.
CJC
&&
.AVIATION...
18Z TAFS
STARTING TO SEE ANOTHER ROUND OF SHOWERS/STORMS BEGIN TO DEVELOP
ACROSS THE MIDSOUTH AS TEMPERATURES CLIMB INTO THE UPPER 80S.
SHOWERS WILL BE HIT AND MISS THROUGH MOST OF THE AFTERNOON...MUCH
LIKE YESTERDAY. AROUND 00-04Z A BAND OF POSSIBLY STRONGER SHOWERS
AND THUNDERSTORMS IS EXPECTED TO DEVELOP NEAR JBR TO LITTLE ROCK
AND MOVE TO THE EAST. TRIED TO TIME THIS UN-DEVELOPED LINE BY
ADDING VCTS TO JBR...THEN MEM AND MKL. HOWEVER TIMING OF THIS
FEATURE WILL BECOME MUCH MORE CERTAIN AFTER...OR EVEN IF IT
DEVELOPS. WILL AMEND WHEN THERE IS SOMETHING MORE CONCRETE TO
TRACK. STRONG WIND AND BRIEF IFR VISIBILITY DUE TO HEAVY RAIN CAN
BE EXPECTED. OTHERWISE...EXPECT PRECIPITATION INTENSITY AND
COVERAGE TO DIMINISH BY 06Z...WITH MVFR TO IFR LOW CLOUDS DURING
TH EARLY MORNING HOURS.
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 76 93 76 94 / 60 40 40 20
MKL 75 89 72 89 / 70 60 50 30
JBR 75 90 72 93 / 70 50 30 20
TUP 74 90 73 92 / 40 40 50 30
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
831 AM CDT SAT SEP 1 2012
.UPDATE...
MOIST CONDITIONS IN PLACE. LATEST OHX SOUNDING SHOWED CONVECTIVE
TEMPS OF 80 DEGREES F WITH A SFC DEW POINT OF 72F. CURRENT TEMPS
ARE IN THE MID TO UPPER 70S. CAP TO AGAIN BE DISMISSED BY 18Z
TODAY AS TEMPS WARM INTO THE 80S. OMEGA FIELDS SEEM TO BE SOMEWHAT
NEUTRAL SO THAT CONVECTION DEVELOPMENT SHOULD STAY ON THE SCT
SIDE BUT SUNSHINE SHOULD REMAIN RATHER LIMITED.
FOR THE FCST...ONLY PARAMETER THAT WILL NEED A TWEAK APPEARS TO BE
THE MAX TEMPS FOR TODAY. HRRR IS IN LINE WITH THE CONVECTIVE
DEVELOPMENT BY AFTERNOON AND THE 18Z PROG TEMPS ARE IN THE LOWER
TO MID 80S. WILL THEREFORE MAKE A SLIGHT DOWNWARD TWEAK TO THE
HIGH TEMPS. THIS MAY OR MAY NOT CHANGE THE ZONE WORDING BUT I WILL
STILL REISSUE. UPDATE OUT SHORTLY.
&&
.PREV DISCUSSION... /ISSUED 651 AM CDT SAT SEP 1 2012/
UPDATE...FOR 12Z AVIATION FORECASTS.
AVIATION...REMNANTS OF FORMER HURRICANE ISAAC CONTINUE TO MOVE
EVER-SO-SLOWLY EASTWARD ACROSS THE MIDDLE MISSISSIPPI VALLEY TODAY
AND TONIGHT, WITH SOUTHERLY FLOW ON THE EAST SIDE KEEPING
OUR ATMOSPHERE CHOCKED FULL OF MOISTURE.
EXPECT A PERIOD OF MVFR CIGS THROUGH 16Z, THEN VFR FOR THE
REMAINDER OF THE DAYLIGHT HOURS. EXPECT SCATTERED THUNDERSTORMS TO
DEVELOP DURING THE AFTERNOON, WITH A CHANCE FOR THUNDERSTORMS TO
IMPACT AREA TERMINALS, ALONG WITH BRIEF PERIODS OF MVFR AND
POSSIBLY IFR CONDITIONS, ESPECIALLY AT CKV AND BNA.
EXPECT SHOWERS AND THUNDERSTORMS TO DIMINISH AT BNA AND CSV AFTER
SUNSET. HOWEVER, SCATTERED TO NUMEROUS SHOWERS ARE FORECAST TO
RE-DEVELOP IN THE CKV AREA AFTER 06Z, AS DEEPEST MOISTURE FROM
ISAAC STARTS TO NOSE INTO NORTHWESTERN MIDDLE TENNESSEE.
SURFACE WINDS WILL BE SOUTHERLY, WITH AFTERNOON GUSTS AT BNA AND
CKV TO 20 KTS.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
21
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
630 PM CDT SUN SEP 2 2012
.SHORT TERM...TONIGHT THROUGH WEDNESDAY
239 PM CDT SUN SEP 2 2012
MAIN FORECAST CONCERNS ARE ON PRECIPITATION CHANCES THROUGHOUT AND
ANY SEVERE WEATHER POTENTIAL FOR MONDAY/LABOR DAY.
CURRENTLY AS OF 20Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A DEEP UPPER LOW OVER SASKATCHEWAN....RIDGING OVER THE
WESTERN GREAT LAKES REGION...AND THE REMNANTS OF ISAAC IN SOUTHWEST
INDIANA. WITHIN THE SOUTHWEST FLOW BETWEEN THE UPPER LOW AND THE
RIDGING...A SHORTWAVE WAS PRESENT FROM LAKE WINNIPEG TO CENTRAL
SOUTH DAKOTA. THE COMBINATION OF DPVA AHEAD OF THIS SHORTWAVE AND
LOW TO MID LEVEL MOISTURE TRANSPORT SURGING NORTH HAS KEPT SOME
SHOWERS AND THUNDERSTORMS GOING OVER NORTHWEST MINNESOTA. THIS
MOISTURE TRANSPORT CAN BE SEEN IN SOME OF THE GOES DERIVED
PRECIPITABLE WATER IMAGERY...WHERE VALUES ARE IN THE 1-1.3 INCH
RANGE FROM EASTERN NEBRASKA INTO WESTERN MINNESOTA. ASSOCIATED WITH
THIS SHORTWAVE AT THE SURFACE IS A COLD FRONT THAT STRETCHES FROM
NORTH CENTRAL MINNESOTA BACK INTO SOUTHEAST SOUTH DAKOTA. OVER OUR
AREA...PLENTY OF SUNSHINE CONTINUES...THANKS TO DRY AIR PRESENT AS
SEEN ON THE 12Z MPX SOUNDING. MIXING FROM THE SUN COMBINED WITH
850MB TEMPS AROUND 18C PER 12Z SOUNDINGS ALLOWING TEMPERATURES TO
CLIMB INTO THE LOW TO MID 80S. SOME CUMULUS HAS FORMED OVER THE
SOUTHEAST HALF OF THE AREA...THOUGH...REFLECTIVE OF ISAAC MOISTURE
BEGINNING TO GET PULLED NORTHWEST AHEAD OF THE SHORTWAVE/FRONT. THAT
MOISTURE CAN BE SEEN TOO ON GOES PRECIPITABLE WATER IMAGERY.
TONIGHT AND MONDAY...THE SHORTWAVE SEEN OVER THE DAKOTAS IS PROGGED
TO PUSH EAST-NORTHEAST IN RESPONSE TO THE DEEP UPPER LOW IN CANADA
HEADING EAST. AS THE SHORTWAVE HEADS INTO THE RIDGE OVER THE
FORECAST AREA...IT LOOKS LIKE IT WILL WEAKEN...BUT COME THROUGH
NORTHERN SECTIONS OF THE FORECAST AREA AT A GOOD TIME FOR CONVECTIVE
INITIATION...I.E. MONDAY AFTERNOON. WITH THE SHORTWAVE WEAKENING...
SO DOES THE FRONT ASSOCIATED WITH IT. HOWEVER...ALSO OF INTEREST IS
MOST MODELS SHOWING A SHORTWAVE COMING OUT OF UTAH/COLORADO RIGHT
NOW. THIS SHORTWAVE GETS PICKED UP BY THE SOUTHWEST FLOW AND ENTERS
THE SOUTHERN PORTION OF THE FORECAST AREA DURING THE AFTERNOON. SO
ALTHOUGH THE SURFACE FRONTAL FEATURE IS WEAKENING...THERE ARE A
COUPLE OF AIDES ALOFT FOR CONVECTION. BEFORE DISCUSSING MONDAY
FURTHER...BACK TO TONIGHT. ANTICIPATING CONVECTIVE DEVELOPMENT ALONG
THE FRONT LATE THIS AFTERNOON OR DURING THE EVENING IN WESTERN
MINNESOTA. THIS ACTIVITY SHOULD WEAKEN OVERNIGHT WITH LOSS OF
HEATING...BUT SOME COULD LINGER AND SCRAPE THE NORTHWEST SECTION OF
THE FORECAST AREA VERY LATE IN THE NIGHT. CERTAINLY THE MOISTURE
TRANSPORT THROUGHOUT THE 925-700MB LAYER STAYING FOCUSED UP WELL TO
THE NORTH DOESNT HELP TO MAINTAIN CONVECTION. IT IS ENTIRELY
POSSIBLE MONDAY MORNING THAT NO PRECIPITATION IS AROUND...A BREAK
BETWEEN THE TONIGHT ACTIVITY DIMINISHING AND AFTERNOON ACTIVITY
STARTING UP. FOR THE AFTERNOON...BUILDING INSTABILITY WITH MLCAPES
OF 1000-2000 J/KG COMBINED WITH THE TWO SHORTWAVES SHOULD INITIATE
CONVECTION. IN FACT...THE ONE SHORTWAVE COMING FROM THE SOUTHWEST
MAY END UP HAVING MOST OF THE CONVECTION...AS NOTED BY THE 02.12Z
SPCWRF-NMM...HIRESW-ARW AND NAM. AS SUCH...HAVE INCREASED
PRECIPITATION CHANCES TO 50 PERCENT SOUTH OF I-90. REGARDING SEVERE
RISK...ONLY AREA OF CONCERN IS AHEAD OF THAT SHORTWAVE...WHERE
LOCALIZED 0-6KM SHEAR VALUES JUMP UP TO 25-30KT. OUTSIDE OF
THAT...0-3KM AND 0-6KM SHEAR VALUES ARE GENERALLY BELOW 20 KTS.
THEREFORE...THINKING MOST CONVECTION NORTH OF I-90 SHOULD STAY
SUB-SEVERE WHILE THERE COULD BE A RISK SOUTH OF I-90. FOR
TEMPERATURES...INCREASING SOUTHERLY FLOW AND CLOUDS WILL RESULT IN A
WARMER NIGHT TONIGHT. SOME CLOUDS AROUND ON MONDAY MAKE HIGHS A
LITTLE DIFFICULT...BUT WITH 850MB TEMPS STILL NEAR 18C AND SOME
SUN...HIGHS SHOULD AT LEAST GET BACK UP INTO THE LOW TO EVEN MID 80S.
MONDAY NIGHT AND TUESDAY...A WEST-SOUTHWEST 500MB FLOW CONTINUES...
AHEAD OF WHAT IS FORECAST TO BE A POTENT SHORTWAVE DROPPING DOWN
INTO SOUTH CENTRAL CANADA AND THE NORTHWEST DAKOTAS BY 00Z
WEDNESDAY. THERE ARE NO REAL DISCERNIBLE SHORTWAVES COMING
THROUGH THE FLOW AND IMPACTING THE FORECAST AREA ACCORDING TO THE
MODELS. LOOKING AT MOISTURE TRANSPORT AND ISENTROPIC LIFT
FIELDS...THERE IS NOTHING REALLY TO NOTE EITHER THAT SUGGEST
PRECIPITATION...AT LEAST FROM THE 02.12Z NAM/GFS. THEREFORE...ONCE
WHATEVER CONVECTION OCCURS MONDAY AFTERNOON PUSHES OFF TO THE
EAST...LIKELY EARLY IN THE EVENING...DRY CONDITIONS COULD OCCUR
RIGHT THROUGH TUESDAY. THIS IS A DEFINITE CHANGE FROM PREVIOUS
MODEL RUNS...EVEN THE 02.00Z ECMWF...WHICH HAD SOME BETTER
MOISTURE TRANSPORT AHEAD OF THAT POTENT SHORTWAVE COMING DOWN TO
INITIATE CONVECTION. FOR NOW WILL LOWER PRECIPITATION CHANCES INTO
THE 15-25 PERCENT RANGE...BUT FUTURE FORECASTS MAY BE ABLE TO PULL
THESE CHANCES ENTIRELY IF TRENDS CONTINUE. ANOTHER ITEM TO WATCH
IS FOG TUESDAY MORNING. IF SKIES CAN CLEAR OUT...DECOUPLING OF
WINDS AND ANY RAIN FROM MONDAY WOULD LEAD TO FOG DEVELOPMENT. DUE
TO UNCERTAINTY ON CLOUDS...HAVE LEFT OUT FOG. DESPITE THE
SHORTWAVE PASSAGE MONDAY EVENING...850MB TEMPS STAY WARM IN THE
18-20C RANGE THROUGH TUESDAY. IN ADDITION... DEWPOINTS DO NOT LOOK
TO DROP MUCH IF AT ALL. THEREFORE... ANTICIPATING SIMILAR LOW AND
HIGH TEMPERATURES TO TONIGHT AND MONDAY.
TUESDAY NIGHT AND WEDNESDAY...THAT POTENT SHORTWAVE TROUGH COMING
INTO THE NORTHWEST DAKOTAS LATE TUESDAY IS WELL AGREED UPON BY
MODELS TO MOVE OVER MINNESOTA BY 12Z WEDNESDAY...THEN CONTINUE ITS
FAST MOTION EAST AND REACH WESTERN LOWER MICHIGAN BY 00Z THURSDAY.
PRETTY STRONG FORCING THIS TROUGH...NOTED IN 500-300MB PV
FIELDS...THOUGH MOST OF IT STAYS NORTH OF THE FORECAST AREA. THERE
IS SOME MOISTURE TRANSPORT AND ISENTROPIC LIFT ACCOMPANYING THE
TROUGH...SO WITH THE WEAK HEIGHT FALLS IN OUR AREA WE SHOULD SEE
SOME PRECIPITATION MOVE THROUGH. MOST LIKELY TIME PERIOD APPEARS TO
OCCUR BETWEEN 06Z-18Z WEDNESDAY. PREVIOUS FORECAST PRECIPITATION
CHANCES REFLECT THIS WELL. STRONG ISENTROPIC DESCENT AND SUBSIDENCE
BEHIND THE TROUGH WILL ALLOW FOR DRYING AND CLEARING CONDITIONS
AFTER 18Z WEDNESDAY. THEREFORE...HAVE DRIED OUT THE FORECAST AREA
FOR THE AFTERNOON. NOTE...IT COULD ALSO BE PRETTY BREEZY IN THE
AFTERNOON AS PRESSURE GRADIENT BRIEFLY TIGHTENS...DEEP MIXING AND
COLD ADVECTION OCCUR. REGARDING TEMPERATURES...850MB TEMPS HOLD
BETWEEN 18-20C TUESDAY NIGHT...BUT ONCE THE FRONT MOVES THROUGH WITH
THE SHORTWAVE WEDNESDAY MORNING...THESE TEMPS FALL TO 10-12C BY 00Z
THURSDAY. STILL...HIGHS ON WEDNESDAY SHOULD BE ABLE TO TOP OUT IN
THE MID 70S TO LOW 80S WITH THE SUN IN THE AFTERNOON. WARM NIGHT
LIKELY TUESDAY NIGHT AHEAD OF THE FRONT AND RELATIVELY HIGH
DEWPOINTS.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
239 PM CDT SUN SEP 2 2012
SURPRISINGLY...THE 02.12Z ECMWF/GFS/CANADIAN AND GFS ENSEMBLES ARE
ALL IN REALLY GOOD AGREEMENT WITH THE UPPER AIR AND SURFACE PATTERNS
THROUGH SATURDAY. SOME DIFFERENCES START TO SHOW UP ON SUNDAY...BUT
GIVEN THE AMPLIFICATION FORECAST TO OCCUR...IT IS SURPRISING TO SEE
THE GOOD AGREEMENT. THE LONG TERM PERIOD STARTS OFF WITH UPPER
TROUGHING OVER MUCH OF CENTRAL CANADA WITH A POTENT SHORTWAVE
DROPPING DOWN THROUGH ALBERTA. THIS SHORTWAVE ENDS UP CARVING OUT A
FAIRLY DEEP TROUGH AS IT DIGS SOUTHEAST...REACHING THE OHIO VALLEY
SATURDAY MORNING. AS THIS SHORTWAVE DIGS...A FRONTOGENESIS ZONE
LOOKS TO FORM ACROSS THE FORECAST AREA. THIS APPEARS TO OCCUR
THURSDAY NIGHT AND LASTS THROUGH FRIDAY NIGHT. OVERALL...THE BEST
MOISTURE AND FRONTOGENESIS FORCING STAYS SOUTH...THEREFORE
PRECIPITATION CHANCES ARE ONLY IN THE 20-30 RANGE. ON SATURDAY...
BOTH THE 02.00Z AND 02.12Z ECMWF END UP DEVELOPING A RELATIVELY
STRONG SURFACE LOW IN INDIANA...PARTIALLY CAUSED BY THE UPPER TROUGH
BEGINNING TO CLOSE OFF. THE 02.00Z ECMWF HAD DEFORMATION SHOWERS
INTO THE SOUTHEASTERN HALF OF THE FORECAST AREA FOR SATURDAY.
HOWEVER...THE NEW 02.12Z ECMWF HAS SHOVED THEM OFF TO THE EAST. FOR
NOW...JUST PLACED A 20 PERCENT CHANCE IN THE AREA AROUND GRANT
COUNTY. THE GFS AND CANADIAN ARE MOSTLY DRY. THE REST OF THE WEEKEND
AND GOING INTO EARLY NEXT WEEK WILL ALL HINGE ON WHAT HAPPENS WITH
THE UPPER TROUGH/LOW. THE NEW 02.12Z ECMWF KEEPS IT OVER
INDIANA...LIKE SOME OF THE 02.12Z GFS ENSEMBLES. THE 02.12Z GFS HAS
IT MORE PROGRESSIVE. EITHER SOLUTION LOOKS DRY FOR THE FORECAST
AREA...BUT CLOUDS AND TEMPERATURES WOULD BE GREATLY AFFECTED...WITH
THE FARTHER WEST SOLUTION HOLDING MORE CLOUDS AND COOLER AIR IN THE
FORECAST AREA. SOME OF THE MOVEMENT OF THE UPPER TROUGH/LOW WILL
DEPEND ON TROPICAL STORM LESLIE WHICH IS FORECAST TO MOVE THROUGH
THE WESTERN ATLANTIC AND STRENGTHEN...LIKELY BLOCKING UP THE FLOW.
REGARDING TEMPERATURES...THEY WILL BE ON THE COOL DOWN AS THE UPPER
TROUGH FORMS. 850MB TEMPS FALL FROM THE 10-12C ON THURSDAY TO 6-8C
ON SATURDAY. AS SUCH...HIGHS ARE ONLY FORECAST TO PERHAPS REACH 70
ON SATURDAY. SATURDAY NIGHT COULD BE QUITE COOL...DEPENDING ON
CLOUDS...WITH HIGH PRESSURE POSSIBLY MOVING IN AT THE SURFACE FROM
THE NORTHWEST. SOME SLIGHT REBOUND IN TEMPERATURES ARE ANTICIPATED
ON SUNDAY.
&&
.AVIATION...TONIGHT AND MONDAY
630 PM CDT SUN SEP 2 2012
A COLD FRONT NOW ENTERING WESTERN MINNESOTA WILL CONTINUE TO
PROGRESS EASTWARD THROUGH THE TAF PERIOD...PUSHING THOUGH THE TAF
SITES AFTER 18Z MONDAY. THIS FRONT IS EXPECTED TO TRIGGER
CONVECTION THIS EVENING...BUT ALL THE SHORT TERM MODELS INDICATING
IT TO WEAKEN AS ITS TRACKS EASTWARD. CONFIDENCE OF ANY CONVECTION
REACHING AS FAR WEST AT KRST IS LOW AND DID NOT MENTION IN THE
TAFS. WILL SEE AN INCREASE IN HIGH CLOUDS OVERNIGHT...BUT CEILINGS
EXPECTED TO REMAIN IN THE VFR CATEGORY. WITH THE INCREASING HIGH
CLOUDS...SOUTHEAST SURFACE WINDS OF 5-10 KNOTS AND STRONGER WINDS
ALOFT SHOULD PRECLUDE ANY DENSE FOG FORMATION WITH ONLY PERHAPS SOME
4SM-5SM BR POSSIBLE LATE. NEXT QUESTION IS CONVECTIVE POTENTIAL
MONDAY AFTERNOON AS FRONT PUSHES THROUGH THE AREA. MODELS
INDICATING BEST CHANCES AT KLSE FOR A FEW HOURS IN THE AFTERNOON
AND DID INCLUDE VCSH. HOWEVER...KRST LOOKS TO REMAIN DRY AS
CONVECTIVE DEVELOPMENT EXPECTED TO BE FURTHER EAST. VFR CEILINGS
LIKELY...BUT CANNOT RULE OUT SOME IFR/MVFR CEILINGS WITH ANY
STORMS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
239 PM CDT SUN SEP 2 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
257 AM CDT SAT SEP 1 2012
.SHORT TERM...TODAY THROUGH TUESDAY
257 AM CDT SAT SEP 1 2012
THE MAIN FOCUS IN THE SHORT TERM IS WITH THE TEMPERATURES THIS
WEEKEND FOLLOWED BY THE PRECIPITATION CHANCES MONDAY INTO TUESDAY.
CURRENTLY...A BROAD RIDGE OF SURFACE HIGH PRESSURE SITS ACROSS
ONTARIO AND THE UPPER MISSISSIPPI RIVER VALLEY TO GREAT LAKES
REGION WHILE THE REMNANTS OF ISAAC TRACK NORTHEAST ACROSS
MISSOURI. CIRRUS HAS SPILLED NORTHWARD FROM ISAAC AND HAS HELPED
TO KEEP TEMPERATURES UP A BIT DESPITE THE CIRRUS BEING FAIRLY
THIN. WITH THE RIDGE FIRMLY IN PLACE ACROSS THE REGION...THE
REMNANTS OF ISAAC WILL HAVE A HARD TIME MAKING IT NORTH AND SHOULD
TAKE MORE OF AN EASTERLY TRACK OVER THE NEXT FEW DAYS. WITH THIS
INFLUENCE FROM THE RIDGE...ANY OF THE OUTER BANDS OF PRECIPITATION
SHOULD REMAIN TO THE SOUTHEAST OF THE FORECAST AREA INTO EASTERN
IOWA AND NORTHERN ILLINOIS. THE MAIN INFLUENCE FROM ISAAC MAY BE
ON THE TEMPERATURES ACROSS SOUTHERN WISCONSIN AND NORTHEAST IOWA
IF SOME DENSER MID TO UPPER LEVEL CLOUDS MOVE IN AND HELP TO
SUPPRESS TEMPERATURES A FEW DEGREES TODAY.
AS THE LOW LEVEL FLOW BECOMES MORE SOUTHERLY ON SUNDAY AHEAD OF
THE NEXT TROUGH/COLD FRONT...TEMPERATURES WILL CLIMB A TAD INTO
THE MID TO UPPER 80S. THIS FRONT WILL MOVE ACROSS MINNESOTA LATE
SUNDAY NIGHT INTO MONDAY MORNING AND SHOULD CROSS THE FORECAST
AREA DURING THE DAY MONDAY WITH THE 01.00Z NAM/GFS/ECMWF/GEM ALL
IN REASONABLE AGREEMENT WITH THIS TIMING. THIS FROPA TIMING WOULD
BE IDEAL FOR CONVECTIVE INITIATION DURING THE PEAK DIURNAL HEATING
HOURS OF THE DAY. HOWEVER...GUIDANCE ALSO SHOWS THE BETTER
500-300MB PV ADVECTION BEING UP TO THE NORTH ACROSS CENTRAL
MINNESOTA INTO NORTHERN WISCONSIN WITH NOT MUCH IN THE WAY OF LOW
LEVEL FRONTOGENESIS. 0-3KM MUCAPE DOES INCREASE TO BETWEEN
1000-2000 J/KG AHEAD OF THE FRONT AND IS UNCAPPED...SO ANY KIND OF
TRIGGER SHOULD AT LEAST PRODUCE SOME SCATTERED CONVECTION ALONG
THE FRONT. 0-3KM BULK WIND SHEAR DOES INCREASE TO AROUND 15-25KTS
JUST AHEAD OF THE FRONT IN WESTERN TO CENTRAL WISCONSIN AND BUFKIT
SOUNDINGS SHOW A DRY LAYER AROUND 650MB...SO SOME STRONGER WIND
GUSTS MAY OCCUR IF CONVECTION CAN DEVELOP. THUS...HAVE BUMPED UP
THE CHANCES FOR SHOWERS/STORMS MONDAY AFTERNOON.
AS THIS FRONT MOVES EAST AND CONTINUES TO WEAKEN...A BRIEF BREAK
IN THE FORM OF A SURFACE RIDGE WILL MOVE THROUGH MONDAY EVENING
BEFORE LOW LEVEL MOISTURE TRANSPORT INCREASES AHEAD OF THE NEXT
TROUGH. CONVECTION WILL LIKELY INITIATE IN EASTERN SOUTH DAKOTA
DURING THE AFTERNOON MONDAY AND REDEVELOP EAST ALONG THE NOSE OF
MOISTURE TRANSPORT INTO THE REGION OVERNIGHT INTO TUESDAY. THIS
FRONTAL PASSAGE...WHICH MAY NOT OCCUR UNTIL MID WEEK...WILL
PROVIDE THE BEST CHANCES FOR PRECIPITATION
.LONG TERM...TUESDAY NIGHT THROUGH FRIDAY
257 AM CDT SAT SEP 1 2012
THE BEST CHANCES FOR PRECIPITATION ACROSS THE REGION WILL COME
THROUGH MID WEEK AS A COLD FRONT PASSES. THIS TRAILING COLD FRONT
WILL BE THE MAIN FOCUS FOR RAIN CHANCES THOUGH THE INCREASING LOW
LEVEL MOISTURE TRANSPORT WILL BE NOSING UP INTO THE REGION AHEAD
OF TIME TUESDAY NIGHT INTO WEDNESDAY. 01.00Z GFS/ECMWF/GEM ARE ALL
IN FAIRLY GOOD AGREEMENT WITH BRINGING THIS COLD FRONT THROUGH
THE REGION THROUGH THE DAY WEDNESDAY WITH IT TO LAKE MICHIGAN BY
00Z THURSDAY. THIS FRONT WILL MARK THE START OF A PATTERN SHIFT
TO HAVING A MORE NORTHWESTERLY FLOW ALOFT THAT WILL USHER IN
COOLER AIR FROM CANADA. WHILE HIGH PRESSURE WILL MAINLY BE IN
PLACE ACROSS THE REGION...THERE HAVE BEEN SOME INDICATIONS OF
A SYSTEM DROPPING DOWN FROM SOUTH CENTRAL CANADA THURSDAY NIGHT
INTO FRIDAY...THOUGH THE TREND APPEARS TO BE TAKING THIS SYSTEM
MORE TO THE WEST AND MISSING THE REGION. CONFIDENCE IS NOT VERY
HIGH AT THIS POINT IN REGARD TO THESE PRECIPITATION CHANCES LATER
IN THE WEEK DUE TO THE AMOUNT OF CHANGES THAT SEEM TO COME WITH
EACH NEW RUN AND THIS SYSTEM.
&&
.AVIATION...THROUGH 06Z SUNDAY
1058 PM CDT FRI AUG 31 2012
WINDS HAVE GONE CALM AT KLSE WITH 01.01Z RAP BUFKIT SOUNDINGS
STILL SHOWING 30 KNOTS AT 015K FEET OVERNIGHT. THUS CONTINUED THE
MENTION OF LLWS AT KLSE. CIRRUS FROM THE REMNANTS OF ISAAC WILL
CONTINUE OVER THE TAF SITES THROUGH THE TAF PERIOD WITH VFR
CEILINGS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
257 AM CDT SAT SEP 1 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS ALBANY NY
129 AM EDT MON SEP 3 2012
.SYNOPSIS...
HIGH PRESSURE WILL KEEP OUR REGION MAINLY DRY THROUGH MONDAY. THE
REMNANTS OF ISAAC WILL APPROACH THE AREA ON LABOR DAY...BRINGING
AN INCREASE IN CLOUDINESS AND A THREAT OF RAIN STARTING MONDAY
NIGHT AND CONTINUING THROUGH THE MID WEEK PERIOD. RAIN WILL BE
HEAVY AT TIMES.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 100 AM EDT...SKIES REMAIN MOSTLY CLEAR ACROSS THE
REGION...WITH THE EXCEPTION OF PATCHY LOW CLOUDS DEVELOPING ACROSS
PORTIONS OF THE LITCHFIELD HILLS AND MID HUDSON VALLEY.
EVENTUALLY...WINDS SHOULD GRADUALLY VEER MORE INTO THE
E/SE...WHICH SHOULD BRING INCREASING LOW LEVEL MOISTURE BACK INTO
THE REGION...ESPECIALLY LATE. THE LATEST NAM 12 AND RUC BOTH
DEPICT LOW CLOUDS DEVELOPING ACROSS WESTERN MA AND NW CT AROUND OR
SHORTLY AFTER MIDNIGHT...THEN EXPANDING WEST INTO THE SE
CATSKILLS...AND POSSIBLY NORTHWARD WITHIN THE HUDSON RIVER VALLEY
FROM ALBANY SOUTH BY DAYBREAK. WILL ONLY MENTION PARTLY CLOUDY
SKIES FOR MOST AREAS AS CLOUDS SHOULD BE RATHER PATCHY. IN
ADDITION...PATCHY FOG MAY FORM WITHIN RIVER VALLEYS...AND ALSO
ACROSS HIGHER ELEVATIONS ACROSS THE GREENS/BERKSHIRES/LITCHFIELD
HILLS EARLY THIS MORNING.
EXPECT OVERNIGHT MINS TO FALL INTO THE 40S AND 50S ACROSS MOST
AREAS FROM THE MOHAWK RIVER VALLEY NORTH INTO THE SOUTHERN
ADIRONDACKS...WITH 50S TO LOWER 60S FURTHER S AND E...WHERE SOME
CLOUDS AND HIGHER LOW LEVEL MOISTURE AMOUNTS SHOULD DEVELOP.
ON LABOR DAY...EXPECT MID AND HIGH CLOUDS TO INCREASE FROM
SOUTHWEST TO NORTHEAST WITH SOME WIDELY SCATTERED SHOWERS
DEVELOPING DURING THE AFTERNOON ACROSS SW PTNS OF THE FA. HIGHS
ARE EXPECTED TO BE IN THE MID 70S TO AROUND 80.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
WHILE QPF AMOUNTS VARY SOME AMONGST THE MODELS...ALL THE GUIDANCE
SUGGESTS THAT THE REMNANTS OF ISAAC WILL IMPACT OUR REGION THROUGH
THE MID WEEK PERIOD WITH INCREASING POPS MONDAY NIGHT ESPECIALLY
DURING THE SECOND HALF OF THE NIGHT AND THEN LIKELY TO CATEGORICAL
POPS TUESDAY INTO WEDNESDAY ALTHOUGH ACTIVITY MAY START TO
DIMINISH BY WEDNESDAY AFTERNOON WITH STEADIER PCPN BECOMING MORE
SCATTERED ESPECIALLY ACRS NW PTNS OF THE FA. THE HEAVIEST PCPN AT
THIS TIME APPEARS TO BE DURING THE TUESDAY AFTERNOON THROUGH
WEDNESDAY MORNING TIME FRAME ACRS THE BULK OF THE REGION. THIS IS
THE PERIOD WHEN THE H10-H8 THETA E RIDGE IS THE STRONGEST ACRS THE
FA SLIDING FORM NW TO SE WITH TIME AS WELL AS PWATS 1.5 TO
SLIGHTLY OVER 2 INCHES.
SPECIFICALLY FOR THE PERIOD FROM MONDAY NIGHT THROUGH
WEDNESDAY...EXPECT CHANCES OF RAIN AND ISOLATED THUNDERSTORMS
TO INCREASE FROM SOUTHWEST TO NORTHEAST ACROSS THE REGION MONDAY
NIGHT. RAIN AND ISOLATED THUNDERSTORMS WITH RAINFALL HEAVY AT
TIMES CONTINUE TUESDAY AND TUESDAY NIGHT. ON WEDNESDAY EXPECT THE
HEAVIEST RAIN IN THE MORNING WITH MORE SCATTERED CONVECTION DURING
THE AFTERNOON. ON WEDNESDAY THERE MAY ALSO BE SOME BREAKS IN THE
OVERCAST WHICH COUPLED WITH SURFACE HEATING AND AN UNSTABLE
AIRMASS STILL IN PLACE WILL INCREASE THE CHANCE FOR
THUNDERSTORMS...SO HAVE CHANCE OF THUNDERSTORMS MENTIONED ON
WEDNESDAY. WHILE THE THUNDERSTORMS ARE NOT EXPECTED TO BE SEVERE
MORE HEAVY DOWNPOURS ARE POSSIBLE. EXPECT LOWS MONDAY NIGHT IN THE
MID 70S TO MID 80S.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A SECONDARY COLD FRONT WILL IMPACT THE FORECAST AREA IN THE WAKE OF
THE MOISTURE ASSOCIATED ISAAC WED NIGHT INTO THU. THE GFS SHOWS
MODEST AMOUNTS OF INSTABILITY WITH SFC DEWPTS IN THE M50S TO L60S.
PWATS REMAIN AROUND AN INCH. THE BEST CHANCE OF SHOWERS AND
THUNDERSTORMS WILL BE WITH THE COLD FRONT THU. MAX TEMPS WILL
GENERALLY BE IN THE M70S TO L80S.
THU NIGHT THRU FRI NIGHT...THE HPC GUIDANCE/GFS/ECMWF SHOW A BREAK
IN THE MID WEEK UNSETTLED WEATHER...WITH HIGH PRESSURE BUILDING IN
FROM THE OHIO VALLEY OVER PA AND THE NORTHEAST. LOWER HUMIDITY
LEVELS AND DRY CONDITIONS WILL PREVAIL BEFORE THE NEXT UPSTREAM
SYSTEM OVER THE CNTRL MS RIVER VALLEY IMPACTS NY AND NEW ENGLAND ON
THE WEEKEND. LOWS WILL BE IN 50S TO L60S THU NIGHT...AND U40S TO
U50S FRI NIGHT. NEAR NORMAL HIGHS ARE EXPECTED ON FRI IN THE M70S
TO NEAR 80F IN THE VALLEYS...AND U60S TO M70S OVER THE HILLS AND
MTNS.
SATURDAY INTO SUNDAY...SOME TIMING DIFFERENCES FOR NEXT WEEKEND WITH
THE EVOLUTION OF THE POSITIVELY TILTED LONGWAVE TROUGH OVER THE ERN
HALF OF THE CONUS AND THE DEVELOPING SW FLOW ALOFT OVER THE ERN
SEABOARD. THE FRONTAL BOUNDARY ON THE LEADING EDGE OF THE UPPER
TROUGH WILL LIKELY HANG TO THE WEST OF THE COASTAL PLAIN WITH
PERHAPS AREAS OF LOW PRESSURE BRINGING SHOWERS/RAINFALL TO THE FCST
AREA BOTH DAYS ON THE WEEKEND. SOME OF THE GUIDANCE WOULD KEEP SAT
DRY...AND SUNDAY MORE UNSETTLED. THIS UPPER TROUGH SHOULD HELP
STEER LESLIE FAR ENOUGH EAST OF NEW ENGLAND FOR NO SIGNIFICANT
IMPACTS. WE TRENDED CLOSER TO THE LATEST HPC GUIDANCE WITH A LOW
CHANCE OF SHOWERS EACH DAY. HIGHS WILL BE SEASONABLE FOR THE 2ND
WEEKEND OF SEPT.
OVERALL...TEMPS WILL TREND SLIGHTLY ABOVE NORMAL...AND PCPN MAY BE
NEAR NORMAL OR SLIGHTLY ABOVE FOR THE EXTENDED.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE WILL MOVE EAST OF MAINE THROUGH THE EARLY MORNING
HOURS. A WARM FRONT WILL SLOWLY APPROACH FROM THE OHIO VALLEY AND
PENNSYLVANIA LATER TODAY.
LOW LEVEL MOISTURE WILL GRADUALLY INCREASE FROM THE SOUTHEAST
LATER THROUGH THE EARLY MORNING HOURS. THIS SHOULD ALLOW
STRATUS/MIST AND MVFR/IFR CONDITIONS TO DEVELOP...ESPECIALLY AT
KPOU AND KPSF...BUT AT LEAST SCATTERED CLOUDS BETWEEN 1000-3000
FEET ARE EXPECTED AT ALL SITES THROUGH THE EARLY MORNING HOURS.
SOME AREAS OF FOG...ESPECIALLY NEAR KGFL/PSF MAY FORM LATE TONIGHT
AS WELL.
THE LOW STRATUS AND/OR ANY FOG WILL DISSIPATE BTWN 12Z-
15Z/MON...HOWEVER A HIGHER STRATUS DECK WILL INCREASE THROUGHOUT
THE DAY...AS A LOW PRESSURE SYSTEM AND ITS WARM FRONT MOVES INTO
THE AREA.
WINDS THROUGH THE EARLY MORNING HOURS WILL BE LIGHT TO CALM AND
SHIFT TO MORE OF A SOUTHEAST DIRECTION AFTER 12Z AT 5-10 KTS.
WINDS MAY BE A BIT STRONGER AT KALB DUE TO FUNNELING EFFECTS UP
THE HUDSON RIVER VALLEY.
OUTLOOK...
MON NIGHT...VFR BECOMING MVFR/IFR. CHC -SHRA AND ISOL -TSRA LATE.
TUE...MVFR/IFR. SHRA LIKELY.
WED-THU...VFR/MVFR. CHC -SHRA/-TSRA.
FRI...VFR...NO SIG WX.
&&
.FIRE WEATHER...
HIGH PRESSURE WILL KEEP OUR REGION MAINLY DRY THROUGH TONIGHT.
THE REMNANTS OF ISAAC WILL APPROACH THE AREA ON LABOR
DAY...BRINGING AN INCREASE IN CLOUDINESS AND A THREAT OF SHOWERS
STARTING MONDAY NIGHT AND CONTINUING THROUGH THE MID WEEK PERIOD.
RELATIVE HUMIDITIES WILL INCREASE TO 80 TO 100 PERCENT
TONIGHT...DROP TO 50 TO 70 PERCENT ON MONDAY...RECOVER TO 100
PERCENT MONDAY NIGHT...AND ONLY DROP TO 70 TO 90 PERCENT ON TUESDAY.
WINDS WILL BE LIGHT AND VARIABLE TONIGHT...AND SOUTH TO SOUTHEAST
MONDAY THROUGH TUESDAY.
&&
.HYDROLOGY...
MAINLY DRY WEATHER IS EXPECTED THROUGH LABOR DAY. THE REMNANTS OF
ISAAC WILL INTERACT WITH A FRONT AND BRING RAIN TO OUR AREA
BEGINNING MONDAY NIGHT AND CONTINUING THROUGH THE MID WEEK PERIOD.
AT THIS TIME THE LATEST MODEL GUIDANCE SUGGESTS A WIDESPREAD 1 TO
3 INCHES OF RAIN WITH LOCALLY HIGHER AMOUNTS OF AROUND 4 INCHES
ACROSS SOUTHEAST PORTIONS OF THE AREA. NO RIVER FLOODING IS FORECAST
AT THIS TIME.
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...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...11/JPV
NEAR TERM...KL/11/JPV
SHORT TERM...11
LONG TERM...WASULA
AVIATION...NAS
FIRE WEATHER...11
HYDROLOGY...11
AREA FORECAST DISCUSSION
NWS ALBANY NY
102 AM EDT MON SEP 3 2012
.SYNOPSIS...
HIGH PRESSURE WILL KEEP OUR REGION MAINLY DRY THROUGH MONDAY. THE
REMNANTS OF ISAAC WILL APPROACH THE AREA ON LABOR DAY...BRINGING
AN INCREASE IN CLOUDINESS AND A THREAT OF RAIN STARTING MONDAY
NIGHT AND CONTINUING THROUGH THE MID WEEK PERIOD. RAIN WILL BE
HEAVY AT TIMES.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 100 AM EDT...SKIES REMAIN MOSTLY CLEAR ACROSS THE
REGION...WITH THE EXCEPTION OF PATCHY LOW CLOUDS DEVELOPING ACROSS
PORTIONS OF THE LITCHFIELD HILLS AND MID HUDSON VALLEY.
EVENTUALLY...WINDS SHOULD GRADUALLY VEER MORE INTO THE
E/SE...WHICH SHOULD BRING INCREASING LOW LEVEL MOISTURE BACK INTO
THE REGION...ESPECIALLY LATE. THE LATEST NAM 12 AND RUC BOTH
DEPICT LOW CLOUDS DEVELOPING ACROSS WESTERN MA AND NW CT AROUND OR
SHORTLY AFTER MIDNIGHT...THEN EXPANDING WEST INTO THE SE
CATSKILLS...AND POSSIBLY NORTHWARD WITHIN THE HUDSON RIVER VALLEY
FROM ALBANY SOUTH BY DAYBREAK. WILL ONLY MENTION PARTLY CLOUDY
SKIES FOR MOST AREAS AS CLOUDS SHOULD BE RATHER PATCHY. IN
ADDITION...PATCHY FOG MAY FORM WITHIN RIVER VALLEYS...AND ALSO
ACROSS HIGHER ELEVATIONS ACROSS THE GREENS/BERKSHIRES/LITCHFIELD
HILLS EARLY THIS MORNING.
EXPECT OVERNIGHT MINS TO FALL INTO THE 40S AND 50S ACROSS MOST
AREAS FROM THE MOHAWK RIVER VALLEY NORTH INTO THE SOUTHERN
ADIRONDACKS...WITH 50S TO LOWER 60S FURTHER S AND E...WHERE SOME
CLOUDS AND HIGHER LOW LEVEL MOISTURE AMOUNTS SHOULD DEVELOP.
ON LABOR DAY...EXPECT MID AND HIGH CLOUDS TO INCREASE FROM
SOUTHWEST TO NORTHEAST WITH SOME WIDELY SCATTERED SHOWERS
DEVELOPING DURING THE AFTERNOON ACROSS SW PTNS OF THE FA. HIGHS
ARE EXPECTED TO BE IN THE MID 70S TO AROUND 80.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
WHILE QPF AMOUNTS VARY SOME AMONGST THE MODELS...ALL THE GUIDANCE
SUGGESTS THAT THE REMNANTS OF ISAAC WILL IMPACT OUR REGION THROUGH
THE MID WEEK PERIOD WITH INCREASING POPS MONDAY NIGHT ESPECIALLY
DURING THE SECOND HALF OF THE NIGHT AND THEN LIKELY TO CATEGORICAL
POPS TUESDAY INTO WEDNESDAY ALTHOUGH ACTIVITY MAY START TO
DIMINISH BY WEDNESDAY AFTERNOON WITH STEADIER PCPN BECOMING MORE
SCATTERED ESPECIALLY ACRS NW PTNS OF THE FA. THE HEAVIEST PCPN AT
THIS TIME APPEARS TO BE DURING THE TUESDAY AFTERNOON THROUGH
WEDNESDAY MORNING TIME FRAME ACRS THE BULK OF THE REGION. THIS IS
THE PERIOD WHEN THE H10-H8 THETA E RIDGE IS THE STRONGEST ACRS THE
FA SLIDING FORM NW TO SE WITH TIME AS WELL AS PWATS 1.5 TO
SLIGHTLY OVER 2 INCHES.
SPECIFICALLY FOR THE PERIOD FROM MONDAY NIGHT THROUGH
WEDNESDAY...EXPECT CHANCES OF RAIN AND ISOLATED THUNDERSTORMS
TO INCREASE FROM SOUTHWEST TO NORTHEAST ACROSS THE REGION MONDAY
NIGHT. RAIN AND ISOLATED THUNDERSTORMS WITH RAINFALL HEAVY AT
TIMES CONTINUE TUESDAY AND TUESDAY NIGHT. ON WEDNESDAY EXPECT THE
HEAVIEST RAIN IN THE MORNING WITH MORE SCATTERED CONVECTION DURING
THE AFTERNOON. ON WEDNESDAY THERE MAY ALSO BE SOME BREAKS IN THE
OVERCAST WHICH COUPLED WITH SURFACE HEATING AND AN UNSTABLE
AIRMASS STILL IN PLACE WILL INCREASE THE CHANCE FOR
THUNDERSTORMS...SO HAVE CHANCE OF THUNDERSTORMS MENTIONED ON
WEDNESDAY. WHILE THE THUNDERSTORMS ARE NOT EXPECTED TO BE SEVERE
MORE HEAVY DOWNPOURS ARE POSSIBLE. EXPECT LOWS MONDAY NIGHT IN THE
MID 70S TO MID 80S.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A SECONDARY COLD FRONT WILL IMPACT THE FORECAST AREA IN THE WAKE OF
THE MOISTURE ASSOCIATED ISAAC WED NIGHT INTO THU. THE GFS SHOWS
MODEST AMOUNTS OF INSTABILITY WITH SFC DEWPTS IN THE M50S TO L60S.
PWATS REMAIN AROUND AN INCH. THE BEST CHANCE OF SHOWERS AND
THUNDERSTORMS WILL BE WITH THE COLD FRONT THU. MAX TEMPS WILL
GENERALLY BE IN THE M70S TO L80S.
THU NIGHT THRU FRI NIGHT...THE HPC GUIDANCE/GFS/ECMWF SHOW A BREAK
IN THE MID WEEK UNSETTLED WEATHER...WITH HIGH PRESSURE BUILDING IN
FROM THE OHIO VALLEY OVER PA AND THE NORTHEAST. LOWER HUMIDITY
LEVELS AND DRY CONDITIONS WILL PREVAIL BEFORE THE NEXT UPSTREAM
SYSTEM OVER THE CNTRL MS RIVER VALLEY IMPACTS NY AND NEW ENGLAND ON
THE WEEKEND. LOWS WILL BE IN 50S TO L60S THU NIGHT...AND U40S TO
U50S FRI NIGHT. NEAR NORMAL HIGHS ARE EXPECTED ON FRI IN THE M70S
TO NEAR 80F IN THE VALLEYS...AND U60S TO M70S OVER THE HILLS AND
MTNS.
SATURDAY INTO SUNDAY...SOME TIMING DIFFERENCES FOR NEXT WEEKEND WITH
THE EVOLUTION OF THE POSITIVELY TILTED LONGWAVE TROUGH OVER THE ERN
HALF OF THE CONUS AND THE DEVELOPING SW FLOW ALOFT OVER THE ERN
SEABOARD. THE FRONTAL BOUNDARY ON THE LEADING EDGE OF THE UPPER
TROUGH WILL LIKELY HANG TO THE WEST OF THE COASTAL PLAIN WITH
PERHAPS AREAS OF LOW PRESSURE BRINGING SHOWERS/RAINFALL TO THE FCST
AREA BOTH DAYS ON THE WEEKEND. SOME OF THE GUIDANCE WOULD KEEP SAT
DRY...AND SUNDAY MORE UNSETTLED. THIS UPPER TROUGH SHOULD HELP
STEER LESLIE FAR ENOUGH EAST OF NEW ENGLAND FOR NO SIGNIFICANT
IMPACTS. WE TRENDED CLOSER TO THE LATEST HPC GUIDANCE WITH A LOW
CHANCE OF SHOWERS EACH DAY. HIGHS WILL BE SEASONABLE FOR THE 2ND
WEEKEND OF SEPT.
OVERALL...TEMPS WILL TREND SLIGHTLY ABOVE NORMAL...AND PCPN MAY BE
NEAR NORMAL OR SLIGHTLY ABOVE FOR THE EXTENDED.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE WILL MOVE EAST OF MAINE TONIGHT. A WARM FRONT WILL
SLOWLY APPROACH FROM THE OHIO VALLEY AND PENNSYLVANIA TOMORROW.
LOW LEVEL MOISTURE WILL GRADUALLY INCREASE FROM THE SOUTHEAST
LATER THIS EVENING AND OVERNIGHT. THIS SHOULD ALLOW STRATUS/MIST
AND MVFR/IFR CONDITIONS TO DEVELOP THROUGHOUT THE AREA BETWEEN
MIDNIGHT AND DAYBREAK. SOME AREAS OF FOG...ESPECIALLY NEAR
KGFL/PSF MAY FORM LATE TONIGHT AS WELL.
THE LOW STRATUS AND/OR ANY FOG WILL DISSIPATE BTWN 12Z-
15Z/MON...HOWEVER A HIGHER STRATUS DECK WILL INCREASE THROUGHOUT
THE DAY...AS A LOW PRESSURE SYSTEM AND ITS WARM FRONT MOVES INTO
THE AREA.
WINDS THIS AFTERNOON AND TONIGHT WILL BE LIGHT TO CALM AND SHIFT TO
MORE OF A SOUTHEAST DIRECTION AFTER 08Z/MON AT 5-10 KTS. WINDS
MAY BE A BIT STRONGER AT KALB DUE TO FUNNELING EFFECTS UP THE
HUDSON RIVER VALLEY.
OUTLOOK...
MON NIGHT...VFR BECOMING MVFR/IFR. CHC -SHRA AND ISOL -TSRA LATE.
TUE...MVFR/IFR. SHRA LIKELY.
WED-THU...VFR/MVFR. CHC -SHRA/-TSRA.
FRI...VFR...NO SIG WX.
&&
.FIRE WEATHER...
HIGH PRESSURE WILL KEEP OUR REGION MAINLY DRY THROUGH TONIGHT.
THE REMNANTS OF ISAAC WILL APPROACH THE AREA ON LABOR
DAY...BRINGING AN INCREASE IN CLOUDINESS AND A THREAT OF SHOWERS
STARTING MONDAY NIGHT AND CONTINUING THROUGH THE MID WEEK PERIOD.
RELATIVE HUMIDITIES WILL INCREASE TO 80 TO 100 PERCENT
TONIGHT...DROP TO 50 TO 70 PERCENT ON MONDAY...RECOVER TO 100
PERCENT MONDAY NIGHT...AND ONLY DROP TO 70 TO 90 PERCENT ON TUESDAY.
WINDS WILL BE LIGHT AND VARIABLE TONIGHT...AND SOUTH TO SOUTHEAST
MONDAY THROUGH TUESDAY.
&&
.HYDROLOGY...
MAINLY DRY WEATHER IS EXPECTED THROUGH LABOR DAY. THE REMNANTS OF
ISAAC WILL INTERACT WITH A FRONT AND BRING RAIN TO OUR AREA
BEGINNING MONDAY NIGHT AND CONTINUING THROUGH THE MID WEEK PERIOD.
AT THIS TIME THE LATEST MODEL GUIDANCE SUGGESTS A WIDESPREAD 1 TO
3 INCHES OF RAIN WITH LOCALLY HIGHER AMOUNTS OF AROUND 4 INCHES
ACROSS SOUTHEAST PORTIONS OF THE AREA. NO RIVER FLOODING IS FORECAST
AT THIS TIME.
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...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...11/JPV
NEAR TERM...KL/11/JPV
SHORT TERM...11
LONG TERM...WASULA
AVIATION...KL/WASULA
FIRE WEATHER...11
HYDROLOGY...11
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
430 AM EDT MON SEP 3 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 429 AM EDT MON SEP 3 2012
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WSW FLOW ALF OVER
THE UPR GRT LKS BTWN UPR RDG EXTENDING FM THE PLAINS INTO LWR MI AND
DEEP...OCCLUDED LO OVER NRN SASKATCHEWAN THAT IS DRIFTING ONLY
SLOWLY EWD. THE REMNANTS OF HURRICANE ISAAC CONTINUE TO DRIFT EWD
THRU THE OH VALLEY S OF THE UPR RDG AXIS. WARM CONVEYOR BELT MSTR
RIBBON...IN ADVANCE OF COLD FNT MOVING THRU MN THAT IS ATTENDANT TO
SASKATCHEWAN OCCLUSION...HAS PUSHED INTO ERN MN/WRN UPR MI.
HOWEVER...CIRCULATION ARND ISAAC HAS LIMITED MSTR INFLOW INTO THIS
SYSTEM AS EVIDENCED BY VERY DRY AIRMASS SHOWN ON THE 00Z MPX RAOB
AND H85 DEWPT DEPRESSIONS NEAR 20C STRETCHING FM THAT SITE SWWD INTO
THE CENTRAL PLAINS. SINCE THIS DRY AIR IS FEEDING NEWD TOWARD NE
MN/UPR MI IN THE SSW SFC-H85 FLOW AHEAD OF COLD FNT...AT 06Z THERE
WAS NO PCPN FALLING S OF THE CNDN BORDER FM THIS CLD DESPITE STEEP
MID LVL LAPSE RATES AND MUCAPE 500-1000 J/KG AS SHOWN BY SPC
MESOANALYSIS. ISOLD -SHRA/A FEW LTG STRIKES WERE EVIDENT IN ONTARIO
WHERE MSTR IS DEEPER PER 00Z YPL RAOB CLOSER TO SHARPER DEEP LYR
QVECTOR CNVGC ASSOCIATED WITH OCCLUSION TO THE W. HOWEVER...APRCH OF
70KT H3 JET MAX IN THE NRN PLAINS/SOME UPR DVGC HAS CAUSED MORE
SHRA/TS TO DVLP OVER WRN LK SUP CLOSER TO FCST ISSUANCE. BEHIND THE
COLD FNT IN THE NRN PLAINS...00Z ABERDEEN SDAKOTA AND BISMARCK RAOBS
SHOW A VERY DRY AIRMASS. LATEST WV IMAGERY SHOWS THIS DRIER AIR ALF
SPREADING EWD.
MAIN FCST CONCERNS IN THE SHORT TERM ARE SHRA/TS CHCS TODAY AS COLD
FNT/MSTR RIBBON PRESS TO THE E.
TODAY...COLD FNT IN MN IS PROGGED TO DRIFT INTO UPR MI AND DISSIPATE
AS THIS BNDRY OUTRUNS THE CLOSED LO IN SASKATCHEWAN THAT IS PROGGED
TO DRIFT ONLY SLOWLY INTO MANITOBA. PCPN CHCS WL BE HINDERED BY DRY
ADVECTION NOTED ABOVE AND EXIT OF DEEP LYR QVECTOR CNVGC TO THE N.
HOWEVER...BULK OF MODELS SHOWED THE INCRSG H4-2 UPR DVGC EARLY THIS
MRNG IN ADVANCE OF JET MAX MOVING ENEWD THRU THE NRN PLAINS...SO
WENT WITH SCT -SHRA/TSRA TO START OFF FCST PERIOD OVER THE W WITH
THE SOMEWHAT HIER POPS FARTHER TO THE N CLOSER TO DEEPER MSTR/
LINGERING DEEP LYR QVECTOR CNVGC. THIS UPR DVGC IS PROGGED TO EXIT
TO THE NE BY MID MRNG...SO EXPECT POPS TO DIMINISH FOR A TIME.
QUESTION THEN BECOMES WHETHER DAYTIME HEATING CAN INVIGORATE DIURNAL
CONVECTION IN ABSENCE OF APPRECIABLE DYNAMIC SUPPORT AND AGAINST
ONSLAUGHT OF INCOMING DRY AIR THAT IS PROGGED TO DROP KINX BLO 10
OVER THE W HALF BY 18Z FOLLOWING THE DISSIPATING COLD FROPA PER
FAVORED GFS THAT BEST MATCHES WV IMAGERY TRENDS OF VIGOROUS DRYING
ALF MOVING E FM THE NRN PLAINS. BEST SHOT FOR THIS CONVECTION
APPEARS TO BE OVER THE E AND SCNTRL...WHERE KINX IS PROGGED TO
REMAIN NEAR 30 THRU 18Z AND WHERE DVLPG LK BREEZES MIGHT ENHANCE
LLVL CNVGC. BUT EVEN IN THIS AREA...KINX IS FCST TO FALL BLO 20 BY
00Z EXCEPT FOR AREAS NEAR LK MI. AS FOR SVR THREAT...MODELS DEPICT
DEEP LYR SHEAR AS HI AS 30-35 KTS OVER THE SCNTRL AT 18Z. MODIFIED
GFS FCST SDNG FOR ESC AT 18Z FOR SFC T/TD 83/66 YIELDS SBCAPE NEAR
1400 J/KG DESPITE LESS IMPRESSIVE MID LVL LAPSE RATES FCST IN THAT
AREA. WITH VIGOROUS DRYING ALF...SFC-10K DELTA THETA-E IS PROGGED TO
INCRS TO A SGNFT 25-30C BY LATE IN THE DAY...INCRSG THE DCAPE IN THE
PRESENCE OF UNIDIRECTIONAL WLY FLOW ALF/THREAT FOR DAMAGING WINDS.
DESPITE MID LVL DRYING...FCST HI WBZ NEAR 13K FT WOULD PROBABLY
MINIMIZE THE POTENTIAL FOR LARGE HAIL. BUT MAIN CONCERN IS HOW
VIGOROUS MID LVL DRYING WL IMPACT SHRA/TS CHCS. IN FACT...THE
GREATER SHEAR MIGHT ACT TO ENTRAIN SO MUCH DRIER AIR INTO THE STORM
TOWERS AND LIMIT THE INTENSITY OF THE CONVECTION. WL CONTINUE TO
MENTION THE THREAT OF SOME STRONGER STORMS IN THE HWO. AS FOR HI
TEMPS...MIXING TO H85 ON GFS FCST SDNGS YIELDS HI TEMPS REACHING THE
MID/UPR 80S AWAY FM LK MODERATION...IN GOOD AGREEMENT WITH MAX TEMPS
OBSVD UPSTREAM ON SUN.
TNGT...WITH VIGOROUS UPR DRYING PER THE GFS THAT CAUSES H85-5 MEAN
RH TO FALL AS LO AS 20 PCT BY 06Z...ANY LINGERING SHRA/TS OVER THE
SE CWA IN THE EARLY EVNG WL END WITH LOSS OF DAYTIME HEATING IN THE
ABSENCE OF ANY DYNAMIC SUPPORT. CONSIDERING DRYNESS OF INCOMING
AIRMASS AND LGT WINDS UNDER BUBBLE HI PRES BLDG INTO THE AREA...
TENDED TOWARD THE LOWER GFS GUIDANCE FOR MIN TEMPS. VIGOROUS DRYING
ALF/LGT WINDS FAVOR FOG DEVELOPMENT...SO WENT WITH AREAS OF FOG OVER
MUCH OF THE INTERIOR.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 429 AM EDT MON SEP 3 2012
THE PERIOD STARTS 12Z TUE WITH A CLOSED UPPER LOW OVER NRN
MANITOBA...AND A SFC TROUGH/WEAK COLD FRONT W OF THE CWA. SHORTWAVE
ENERGY IS THEN COMBINED INTO THE SRN SIDE OF THE UPPER LOW THROUGH
WED...CAUSING THE SYSTEM TO MOVE FARTHER W TO FAR NW ONTARIO BY 00Z
THU. EXACTLY WHEN AND WHERE THE SHORTWAVE ENERGY MOVES WILL GREATLY
IMPACT THE FORECAST FOR TUE AND TUE NIGHT...SO CONFIDENCE IS LOWER
FOR THIS TIME PERIOD. WE COULD STAY DRY ACROSS MOST OF THE CWA ON
TUE...AS THE 12Z/02 ECMWF SHOWS DUE TO THE SHORTWAVE STAYING FATHER
TO THE N THAN IN OTHER MODELS. ALSO...MODEL FORECAST SOUNDING SHOW
DIFFERENCES BETWEEN LOW LEVEL MOISTURE WHICH WILL RESULT IN
INCREASED TO DECREASED CIN. WILL NOT CHANGE THE PREVIOUS POP
FORECAST WITH SLIGHT CHANCE TO LOW CHANCE POPS MAINLY IN THE
AFTERNOON. IF SHOWERS AND THUNDERSTORMS DO DEVELOP...THERE MAY BE
SOME STRONG TUE AFTERNOON AS CAPE INCREASES TO AOA 1500 J/KG BUT
0-6 KM SHEAR REMAINS BELOW 25 KTS.
A STRONGER COLD FRONT/SFC TROUGH SHOULD MOVE THROUGH ON WED...BUT
TIMING AND INTENSITY REMAINS IN QUESTION AS MODELS DO NOT HANDLE THE
SITUATION WELL. THIS IS AGAIN RELATED TO THE PATH THE SHORTWAVE
TAKES. THE DIFFERENCES BETWEEN TIMING PLAY OUT THE MOST WITH
THUNDERSTORM INTENSITY ON WED...WITH THE SLOWER GUIDANCE BRING THE
FRONT THROUGH AROUND PEAK HEATING WHICH WOULD RESULT IN MORE
INSTABILITY. THE FASTER MODELS MOVE THINGS THROUGH EARLIER AND
THEREFORE...INSTABILITY RESULTING FROM DAYTIME HEATING IS MAXIMIZED
AOA 1500 J/KG. 0-6KM SHEAR SHOULD BE ON THE ORDER OF 40-50
KTS...WITH 0-1KM SHEAR OF AROUND 15 KTS. FLOW WILL BE MOSTLY
UNIDIRECTIONAL...SO THE SHEAR IS MOSTLY SPEED SHEAR. MORE ALONG THE
LINES OF WORST CASE SCENARIO REGARDING TIMING/INSTABILITY...SOME
STORMS COULD BE SEVERE IN THE AFTERNOON WITH WIND GUSTS BEING THE
PRIMARY HAZARD /DUE PARTY TO DRY MID LEVELS/. THERE WOULD BE A LARGE
HAIL THREAT...BUT THAT IS MORE CONDITIONAL. REGARDLESS OF TIMING OF
THE FRONT...PRECIP DOES LOOK MORE CERTAIN THAN ANY OTHER DAY IN THE
EXTENDED...BUT THAT SHORTWAVE WILL MAKE THINGS TRICKY. INCREASED
POPS TO LIKELY...ESPECIALLY CENTRAL AND E...AND HIGH CHANCE POPS
OVER THE FAR W.
THE UPPER LOW WILL CONTINUE TO MOVE EVERY SO SLOWLY ESE...AND WILL
BE CLOSEST TO THE CWA THU NIGHT. EXPECT 850MB TEMPS AROUND 4-6C THU
INTO FRI..WHICH MAY LEAD TO SOME LAKE EFFECT RAIN DOWNWIND OF N/NW
WINDS. MODEL AGREEMENT AND CONTINUITY DEGRADE SIGNIFICANTLY FRIDAY
THROUGH SUNDAY...SO CONFIDENCE IS SIGNIFICANTLY LOWER FOR NEXT
WEEKEND. IT DOES APPEAR...HOWEVER...THAT A RETURN TO OR EVEN BELOW
NEAR NORMAL TEMPERATURES IS IN STORE FOR THU THROUGH SUN. USED
CONSENSUS OF MODEL GUIDANCE GIVEN UNCERTAINTY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 121 AM EDT MON SEP 3 2012
ALTHOUGH A FEW -SHRA MAY ARRIVE AT KIWD/KCMX LATE TONIGHT AND AT
KSAW LATE MON MORNING AHEAD OF AN APPROACHING COLD FRONT...EXPECT
VFR CONDITIONS AS THE FRONTAL BOUNDARY MOVES THRU THE AREA TODAY AS
LOW-LEVEL DRY AIR HOLDS. THERE IS POTENTIAL FOR STRATUS/FOG TO
DEVELOP AT KSAW LATE MONDAY NIGHT AS MOIST SFC DEWPOINTS REMAIN AND
HIGH PRESSURE SETTLES OVER THE AREA. MODEST LOW-LEVEL JET AHEAD OF
COLD FRONT MAY RESULT IN LLWS AT KIWD/KCMX TONIGHT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 429 AM EDT MON SEP 3 2012
EXPECT S WINDS UP TO 20 KTS IN ADVANCE OF AN APPROACHING COLD FRONT
TO DIMINISH TODAY AS THE FRONT TENDS TO WEAKEN. LIGHT WINDS WILL
THEN PREVAIL THRU TONIGHT AS A WEAK HI PRES SYSTEM MOVES INTO THE
UPPER GREAT LAKES. A SERIES OF LOW PRESSURE SYSTEMS AND COLD FRONTS
WILL MOVE NEAR LAKE SUPERIOR TUESDAY THROUGH SUNDAY...LEADING TO
PERIODS OF INCREASED WINDS. HOWEVER...AT THIS TIME WINDS ARE EXPECTED
TO REMAIN BELOW 25KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...VOSS
MARINE...KC/TITUS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
122 AM EDT MON SEP 3 2012
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 347 PM EDT SUN SEP 2 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A STRONG SHORTWAVE/MID
LEVEL LOW MOVING NE THRU CNTRL SASKATCHEWAN. DOWNSTREAM RIDGE
EXTENDS FROM THE SW PLAINS THRU THE UPPER LAKES WHILE REMNANT OF
ISAAC DRIFTS THRU THE LWR OHIO VALLEY. DUE TO ISAAC...MOISTURE
RETURN THRU THE PLAINS HAS BEEN VERY LIMITED AS 12Z RAOBS SHOW 850MB
DWPT DEPRESSIONS BTWN 15-25C. NONETHELESS...SCT HIGH BASED
-SHRA/TSRA HAVE BEEN OCCURRING ACROSS THE DAKOTAS INTO NW MN TODAY
IN THE VCNTY OF COLD FRONT ASSOCIATED WITH THE PARENT SHORTWAVE OVER
SASKATCHEWAN. A COUPLE OF MINOR SHORTWAVES APPEAR TO BE AIDING THE
CONVECTION. IN THE SHORT TERM...MAIN FOCUS WILL BE ON PCPN CHANCES
LATE TONIGHT THRU MON AS WEAKENING COLD FRONT ARRIVES.
WITH ONLY A NARROW RIBBON OF MOISTURE SUPPORTING PCPN TO THE W...THE
EVENING HRS TONIGHT WILL REMAIN DRY WHILE AWAITING COLD
FRONT/MOISTURE RIBBON TO MOVE CLOSER. IN CONJUNCTION WITH THE COLD
FRONT...A SHORTWAVE NOW OVER THE DAKOTAS WILL LIFT NE TONIGHT. ALONG TAIL
OF WAVE AND LEFT EXIT OF SUPPORTING JET STREAK...SHOULD SEE A BAND
OF SCT CONVECTION TONIGHT. THAT CONVECTION MAY SHIFT OUT OVER LAKE
SUPERIOR AND NW UPPER MI LATE TONIGHT. AS FOR TEMPS...THE HIGHEST
MIN TEMPS TONIGHT WILL BE IN THE DOWNSLOPE AREAS NEAR LAKE
SUPERIOR...PARTICULARLY THE W WHERE MOISTENING WILL BE MORE
PRONOUNCED. TEMPS SHOULDN`T FALL LWR THAN THE MID/UPPER 60S IN THOSE
AREAS. 50S WILL BE THE RULE OVER THE SCNTRL/E.
SHORTWAVE/MID LEVEL LOW CURRENTLY OVER SASKATCHEWAN DRIFTS INTO NRN
MANITOBA MON. WITH MAIN SYSTEM WELL TO THE NW OF HERE...SFC COLD
FRONT WILL BE WEAKENING AS IT REACHES UPPER MI. LACK OF DYNAMICS AND
DIMINISHING LOW-LEVEL CONVERGENCE ALONG FRONT WILL WORK TO LIMIT
COVERAGE OF CONVECTION MON...ESPECIALLY SINCE THERE WILL BE SOME DRY
AIR TO OVERCOME. HOWEVER...NARROW RIBBON OF BOUNDARY LAYER MOISTURE
SHOULD BE SUFFICIENT FOR ISOLD/SCT CONVECTION. AS AFORMENTIONED JET
STREAK AIDING PCPN LATE TONIGHT SHIFTS NE...THE RIGHT ENTRANCE OF
THE JET WILL PROBABLY PROVIDE BEST SUPPORT FOR NEW CONVECTION IN THE
AFTN HRS OVER SCNTRL UPPER MI INTO NE WI. PROVIDED MLCAPE INCREASES
TO UPWARDS OF 1500-2000J/KG PER GFS AND ESPECIALLY NAM...DEEP LAYER
SHEAR OF 30-40KT WILL SUPPORT ORGANIZED STORMS AND SVR POTENTIAL IF
ANY STORMS DO DEVELOP. COVERAGE OF SVR STORMS WOULD LIKELY BE ISOLD.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 347 PM EDT SUN SEP 2 2012
LONG TERM PERIOD STARTS OUT WITH UPPER LOW OVER MANITOBA WHILE
ADDITIONAL SHORTWAVE TROUGH CURRENTLY DIGGING INTO FAR NORTHERN
BRITISH COLUMBIA MERGES WITH THE LOW ON WEDNESDAY. INITIAL FRONT
THAT MOVES THROUGH UPR MICHIGAN ON LABOR DAY LIKELY STALLS OUT
MONDAY NIGHT INTO TUESDAY AS IT PARALLELS UPPER FLOW.
MAJORITY OF SHRA/TSRA...ALBEIT ONLY ISOLD/SCT COVERAGE...SHOULD BE
DIMINISHING BY LATER MONDAY NIGHT. KEPT SMALL POPS IN ONLY FOR THE
SOUTH AND EAST CWA AS THOSE AREAS STAY IN AT LEAST A WEAK AREA OF
RIGHT ENTRANCE JET FORCING. LINGERED SLIGHT CHANCES FOR THE SAME
AREAS THROUGH MOST OF THE NIGHT AS THE SURFACE FRONT REMAINS IN THE
VICINITY AND LOW-LEVEL MOISTURE POOLS ALONG THE BOUNDARY. VERY SMALL
CHANCES BUT CAN NOT COMPLETELY PULL THE POPS JUST YET.
FRONT COULD SERVE AS FOCUS FOR MORE SHRA/TSRA ON TUESDAY AS NAM/00Z
ECMWF INDICATE H85 TROUGH AND THETA-E ADVECTION ARRIVES DURING PEAK
HEATING OF THE AFTERNOON. H85 DWPNTS ON THE LOW SIDE TO START THE
DAY...SO SHOULD SEE BETTER CHANCES OF SHRA/TSRA AFTERNOON AND
EVENING...SPREADING FROM WEST TO EAST AS H85 TROUGH CROSSES AREA.
THOUGH 0-6KM SHEAR 20-25 KTS NOT TOO IMPRESSIVE FOR ORGANIZED SEVERE
STORMS...MLCAPES AOA 1000 J/KG AND HIGH DEWPOINT DEPRESSIONS AT
H7-H5 WITH MOIST LOW-LEVELS POINT TO POSSIBLE GUSTY WINDS WITH ANY
TSRA. ANY SHRA/TSRA WOULD WANE BY LATER EVENING WITH LOSS OF
HEATING/WEAKENING SFC-H85 CONVERGENCE. GFS AND LATEST GEM-NHEM AND
12Z ECMWF FOCUS H85 TROUGH MORE LATER TUESDAY NIGHT AND MORE SO ON
WEDNESDAY WITH ARRIVAL OF PRIMARY COLD FRONT. BASED ON TREND FROM
LATEST ECMWF...DECIDED TO NOT GO TOO HIGH FOR POPS ON TUESDAY.
AS LARGER FORMED UPPER LOW COMPLEX OVER MANITOBA RUMBLES EAST INTO
ONTARIO...EXPECT SHARP COLD FRONT TO SWEEP ACROSS GREAT LAKES REGION
WEDNESDAY AND THURSDAY. WOULD THINK THERE WOULD BE DECENT CHANCE FOR
RAIN WITH THE FROPA. BY TIME FRONT ARRIVES GFS AND GEM-NHEM SHOWS
SHARP H85 WIND SHIFT AND MOISTURE ADVECTION INTO THE AREA. OTHER
MODELS ALREADY SHOVE THE H85 TROUGH THROUGH SHUNTING MORE ABUNDANT
MOISTURE SOUTHEAST OF CWA...BUT AS MENTIONED BEFORE LATEST ECMWF HAS
TRENDED THIS WAY AS WELL. CONSISTENCY ON THESE SOLUTIONS NOT THE
GREATEST. THERE ARE ALSO HINTS THAT YET ANOTHER WEAKER WAVE/H7
MOISTURE MAY BE SLIDING THROUGH AREA WHILE FRONT SLIDES THROUGH.
DETAILS CERTAINLY STILL NEED TO BE SORTED OUT AS TO LOCATION AND
COVERAGE OF BEST RAIN CHANCES ON WEDNESDAY. CHANCE POPS FOR SCT
SHRA/TSRA COVER IT FINE FOR NOW. PRESSURE GRADIENT TIGHTENS
WEDNESDAY NIGHT AND THURSDAY IN WAKE OF THE COLD FRONT BUT OTHER
THAN FOR A BRIEF PERIOD WEDNESDAY EVENING WHERE GFS SHOWS 950-925MB
WINDS 30-35 KTS...H925-H85 WINDS INTO THURSDAY ARE ONLY AROUND 20
KTS. SO EVEN THOUGH STEADY COOLING ALOFT OCCURS INTO THURSDAY...THIS
SYSTEM DOES NOT LOOK TO PRODUCE VERY STRONG WINDS AS EARLY FALL
SYSTEMS SOMETIMES CAN DO. TWO ISSUES THAT WILL NEED TO BE MONITORED
THOUGH IN WAKE OF THE COLD FROPA WILL BE AN INCREASED RISK OF RIP
CURRENTS AND POSSIBLE UPPER LOW TYPE WATERSPOUTS LATER THURSDAY INTO
FRIDAY.
ALTHOUGH HIGH PRESSURE TRIES TO BUILD IN LATE THIS WEEK IT REMAINS
PRETTY WEAK AND DIFFUSE AS UPPER FLOW IS NOT CONFLUENT. BY FAR THE
STRONGER SURFACE FEATURE WILL BE WRAPPED UP SURFACE LOW VICINITY OF
HUDSON BAY AND JAMES BAY. BY LATER THURSDAY INTO FRIDAY CANNOT RULE
OUT AT LEAST LIGHT LK EFFECT SHRA SINCE H85 TEMPS DROP TO 4-6C
/WATER TEMPS STILL RUNNING 18-20C/ AND SINCE THERE COULD BE ANOTHER
WEAKER SHORTWAVE/ADDITIONAL MOISTURE PUSHING INTO WESTERN GREAT
LAKES PER GFS/ECMWF. NOT A BIG CHANCE AS LOW-LEVEL FLOW IS NOT
THAT FAVORABLE GIVEN NEUTRAL TO ANTICYCLONIC LOOK...BUT SOME LIGHT
PRECIP SEEMS POSSIBLE.
MODEL DIFFERENCES EMERGE BY NEXT WEEKEND WITH THE MAIN ISSUE ON HOW
QUICK THE 00Z GFS BRINGS ANOTHER LARGER SCALE TROUGH EAST ACROSS THE
NORTHERN PLAINS. 00Z ECMWF INDICATES RIDGING BUILDS IN ALOFT WITH A
SHARPER SURFACE RIDGE FROM THE PLAINS INTO FAR NORTHERN PORTION OF
UPPER GREAT LAKES. 06Z-12Z RUNS OF GFS HAVE TRENDED ECMWF WAY.
LATEST COUPLE RUNS OF ECMWF POINT TO UPPER LAKES BEING ON THE DRY
FRINGE OF SET OF DISTURBANCES WHICH WOULD BRING RAIN TO PORTIONS OF
GREAT LAKES TO START NEXT WEEKEND. HPC PREFERS TO SIDE WITH ECMWF
IDEA AND THIS FORECAST WILL TILT THAT WAY AS WELL WITH A GENERAL DRY
FCST NEXT WEEKEND. AFTER SLIGHTLY THAN NORMAL HIGH TEMPERATURES
FRIDAY AND SATURDAY...EXPECT SOME MODERATION IN TEMPERATURES BY NEXT
SUNDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 121 AM EDT MON SEP 3 2012
ALTHOUGH A FEW -SHRA MAY ARRIVE AT KIWD/KCMX LATE TONIGHT AND AT
KSAW LATE MON MORNING AHEAD OF AN APPROACHING COLD FRONT...EXPECT
VFR CONDITIONS AS THE FRONTAL BOUNDARY MOVES THRU THE AREA TODAY AS
LOW-LEVEL DRY AIR HOLDS. THERE IS POTENTIAL FOR STRATUS/FOG TO
DEVELOP AT KSAW LATE MONDAY NIGHT AS MOIST SFC DEWPOINTS REMAIN AND
HIGH PRESSURE SETTLES OVER THE AREA. MODEST LOW-LEVEL JET AHEAD OF
COLD FRONT MAY RESULT IN LLWS AT KIWD/KCMX TONIGHT.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 347 PM EDT SUN SEP 2 2012
TIGHTENING PRES GRADIENT BTWN HIGH PRES TO THE E AND AN APPROACHING
COLD FRONT TO THE W WILL RESULT IN SE TO S WINDS INCREASING TO
AROUND 20KT TONIGHT. SOUTHERLY WINDS MAY GUST TO AROUND 25KT AT
HIGHER OBS PLATFORMS...ESPECIALLY OVER CNTRL AND ERN PORTIONS OF THE
LAKE. PRES GRADIENT THEN SLACKENS WITH PASSING/WEAKENING COLD FRONT
MON...RESULTING IN WINDS DIMINISHING BACK TO UNDER 15KT MON INTO
TUE. NEXT COLD FRONT PASSING TUE NIGHT/WED WILL BRING AN INCREASE IN
W TO NW WINDS TO AROUND 20KT...MAYBE HIGHER...LATER WED INTO THU.
WINDS WILL DIMINISH SLIGHTLY FRI AS NEXT TROF PASSES EARLY IN THE
DAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS HASTINGS NE
345 AM CDT MON SEP 3 2012
.SHORT TERM...THROUGH 12Z THURSDAY. OVERNIGHT UPPER AIR ANALYSIS
INDICATES A LONG WAVE RIDGE OVER THE EASTERN CONUS AND A TROUGH
OVER THE WEST. SOUTHWESTERLY TO ZONAL MID AND UPPER LEVEL FLOW
EXISTS OVER THE MUCH OF THE CENTRAL CONUS AS A RESULT. MID AND
UPPER LEVEL JET ENERGY EXTENDS FROM SOUTHERN
CALIFORNIA...NORTHEAST INTO THE NORTHERN PLAINS AND PORTIONS OF
THE CENTRAL PLAINS...AS WELL AS SOUTHERN CANADA...AND THEN
SOUTHEAST INTO THE NORTHEASTERN CONUS. A ~90KT UPPER LEVEL JET
STREAK IS ALSO EVIDENT OVER THE CENTRAL AND NORTHERN ROCKY
MOUNTAIN RANGE. WATER VAPOR IMAGERY INDICATES INCREASED LEVELS OF
MID LEVEL MOISTURE EXTENDING NORTHWARD FROM MEXICO INTO THE
SOUTHWESTERN CONUS...AND THEN NORTHEAST INTO THE CENTRAL PLAINS.
AT THE SURFACE A WEAK COLD FRONT EXTENDS FROM NORTHEAST NEBRASKA
TO SOUTHWEST KANSAS. THE LOW LEVEL WIND FIELD REMAINS FROM THE
SOUTHEAST ACROSS SOUTHEASTERN PORTIONS OF THE OUR CWA...WITH MORE
OF A NORTHERLY LOW LEVEL WIND FIELD NOTED FARTHER NORTHWEST ACROSS
THE AREA BEHIND THE FRONT.
GUIDANCE FROM THE NAM AND OPERATIONAL GFS CONTINUE TO SUGGEST THE
UPPER LEVEL JET STREAK...CURRENTLY OVER THE CENTRAL AND NORTHERN
ROCKY MOUNTAIN RANGE...WILL CONTINUE MOVING EAST/NORTHEAST
TODAY...WITH THE RIGHT-REAR QUADRANT OF THIS JET STREAK SETTING UP
SHOP OVER NORTHERN PORTIONS OF OUR CWA. QPF FIELDS FROM THE
NAM...OPERATIONAL GFS AND SREF-MEAN...AS WELL AS SIMULATED
REFLECTIVITY FROM THE 4KM WRF-NMM AND HRRR ALL SUGGEST ENOUGH OF A
DIRECT THERMAL CIRCULATION AND RESULTANT FRONTOGENESIS WILL BE
PRESENT FOR ISOLATED TO SCATTERED PRECIPITATION PRODUCTION OVER
NORTHERN PORTIONS OF OUR AREA THROUGH 18Z. THESE MODEL SOLUTIONS
HAVE BEEN FAIRLY CONSISTENCE SETS OF GUIDANCE THROUGH THE PAST
THREE DAYS AND AS A RESULT WILL GO AHEAD AND MAINTAIN 20%-30% POPS
MAINLY ACROSS NORTHERN PORTIONS OF OUR CWA THROUGH 18Z. GUIDANCE
SUGGESTS THE UPPER LEVEL JET STREAK WILL WEAKEN AND PUSH
EAST/NORTHEAST OF OUR AREA BY THIS AFTERNOON...WHICH WOULD
OTHERWISE BRING AND END TO THE PRECIPITATION CHANCES ACROSS OUR
AREA. THAT BEING SAID...THERE REMAIN INDICATIONS FROM THE NAM AND
OPERATIONAL GFS OF MULTIPLE SMALL SCALE MID LEVEL PERTURBATIONS
PUSHING NEAR OR OVER THE AREA THROUGH THIS AFTERNOON AND EVENING.
GIVEN THE WEAK FORCING AND DIFFICULTY IN ASSIGNING PRECIPITATION
CHANCES TO AN AREA GIVEN THE SUBTLE NATURE OF THESE SMALL SCALE
PERTURBATIONS...QPF FIELDS FROM THE NAM...OPERATIONAL
GFS...EC...AND SREF-MEAN ARE ALL OVER THE PLACE AND OFFER LITTLE
IN THE WAY OF HELP IN TRYING TO DETERMINE WHERE AFTERNOON
CONVECTION WILL MOST LIKELY BE REALIZED. YESTERDAY AT THIS TIME IT
WAS BELIEVED THE WEAK LOW LEVEL BAROCLINIC ZONE...CURRENTLY OVER
OUR AREA...WOULD SLOWLY DRIFT TO THE SOUTHEAST AND WOULD PROVIDE
ADDITIONAL LOW LEVEL CONVERGENCE FOR SURFACE-BASED CONVECTION
DURING THE AFTERNOON AND EARLY EVENING HOURS. HOWEVER NOW IT
APPEARS THIS BAROCLINIC ZONE WILL QUICKLY EXIT OUR AREA TO THE
SOUTHEAST BY EARLY AFTERNOON AND WILL OFFER LITTLE IN THE WAY OF
ADDITIONAL FORCING FOR CONVECTIVE INITIATION. LONG STORY
SHORT...CONFIDENCE IS VERY LOW REGARDING MEASURABLE PRECIPITATION
BEING REALIZED AT ANY ONE LOCATION ACROSS THE CWA THIS AFTERNOON
AND EVENING. BUT BECAUSE MOST ALL MODELS SUGGEST AT LEAST SOME
ISOLATED CONVECTIVE ACTIVITY WILL BE OBSERVED...AGAIN NO TELLING
WHERE FOR SURE...WILL GO AHEAD AND CARRY 20% POPS ACROSS THE
ENTIRE CWA 18Z MONDAY THROUGH 06Z TUESDAY. AS FOR SEVERE WEATHER
CHANCES THIS AFTERNOON AND EVENING...WILL CONTINUE TO DISREGARD
THE OPERATIONAL GFS WHICH SUGGESTS SURFACE DEW POINTS IN THE MID
70S WILL BE REALIZED ACROSS PORTIONS OF THE CWA THIS AFTERNOON.
BOIVERIFY SUGGESTS BCCONSALL CONTINUES TO BE A GOOD PERFORMER WITH
RESPECT TO SURFACE DEW POINTS ACROSS OUR AREA AND THIS SET OF
GUIDANCE SUGGESTS AFTERNOON DEW POINTS WILL REMAIN GENERALLY IN
THE LOW TO MID 60S ACROSS OUR AREA...WITH PERHAPS A FEW UPPER 60
READINGS ACROSS OUR EAST...WHICH IS ALSO WHAT THE NAM CONTINUES TO
SUGGEST. FOLLOWING CLOSER TO THE NAM WOULD ALSO SUGGEST 0-1KM
MLCAPE VALUES OF ~1000J/KG WILL BE IN PLACE ACROSS THE AREA THIS
AFTERNOON AND EVENING. NOT THAT THESE POTENTIAL INSTABILITY VALUES
ARE SOMETHING TO GET OVERLY EXCITED ABOUT BUT WITH THE UPPER LEVEL
JET AXIS OVER THE AREA...DEEP LAYER BULK SHEAR VALUES ON THE ORDER
OF 40KTS WILL ALSO LIKELY BE PRESENT. ALTHOUGH INITIAL UPDRAFT
STRENGTH WILL LIKELY BE MARGINAL AT BEST FOR LARGE HAIL
PRODUCTION...THE ROTATIONAL POTENTIAL OF SAID UPDRAFT MAY ENHANCE
IT ENOUGH FOR A BETTER HAIL THREAT. GIVEN ALL THIS...IT STILL
SEEMS POSSIBLE THAT UPDRAFT STRENGTH COULD BE STRONG ENOUGH TO
SUPPORT LARGE HAIL AND AS A RESULT...WILL GO AHEAD AND CONTINUE TO
OUTLOOK THE AREA FOR POSSIBLE SEVERE WEATHER THIS AFTERNOON AND
EVENING. LOSS OF DIABATIC HEATING POST-SUNSET SHOULD KILL ANY
CONVECTION BEYOND 03Z THIS EVENING...WITH AN OVERALL LACK IN
KINEMATIC FORCING LIKELY PROVIDING DRY CONDITIONS TO THE AREA 03Z-
18Z TUESDAY.
GUIDANCE FROM THE NAM...OPERATIONAL GFS...AND EC ALL SUGGEST A
MORE SIGNIFICANT MID LEVEL SHORT WAVE WILL PUSH INTO SOUTH CENTRAL
CANADA AND PORTIONS OF THE NORTH CENTRAL CONUS TUESDAY INTO
TUESDAY NIGHT. A RESULTANT AREA OF SURFACE LOW PRESSURE IS
EXPECTED TO PUSH ACROSS THE NORTHERN PLAINS AND UPPER MISSISSIPPI
VALLEY DURING THE SAME TIME PERIOD...WITH AN ASSOCIATED SURFACE
COLD FRONT EXPECTED TO SWEEP ACROSS NEBRASKA. AT THIS TIME THE LOW
LEVEL BAROCLINIC ZONE IS EXPECTED TO NEAR NORTH/NORTHWESTERN
PORTIONS OF OUR CWA BY 00Z WEDNESDAY...LIKELY CLEARING THE ENTIRE
CWA BY 12Z WEDNESDAY. SURFACE-BASED CONVECTION WILL BE POSSIBLE IN
THE VICINITY OF THIS LOW LEVEL BAROCLINIC ZONE ACROSS OUR
NORTH/NORTHWEST BY LATE AFTERNOON TUESDAY...WITH ADDITIONAL
CONVECTIVE ACTIVITY PERHAPS SPREADING SOUTHEAST ACROSS THE CWA
HEADING INTO THE EVENING AND OVERNIGHT HOURS TUESDAY. GIVEN ALL
THIS...WILL GO AHEAD WITH 20%-30% POPS ACROSS THE CWA 21Z TUESDAY
THROUGH 12Z WEDNESDAY. POOLING OF LOW LEVEL MOISTURE AHEAD OF THE
LOW LEVEL BAROCLINIC ZONE...AS SUGGESTED BY THE NAM...MAY ACTUALLY
HELP TO INCREASE POTENTIAL INSTABILITY ACROSS OUR AREA WHEN
COMPARED TO MONDAY...WITH THE NAM SUGGESTING 0-1KM MLCAPE VALUES
ON THE ORDER OF 1500J/KG POSSIBLE TUESDAY AFTERNOON INTO THE
EVENING HOURS. IN ADDITION...DEEP LAYER BULK SHEAR VALUES OF
AROUND 35KTS WILL ALSO BE IN EXISTENCE. GIVEN ALL THIS...WILL
CONTINUE THE SEVERE WEATHER MENTION IN THE HWO FOR TUESDAY.
A COOLER AND DRIER AIRMASS WILL SETTLE IN ACROSS THE AREA BEHIND
THE LOW LEVEL BAROCLINIC ZONE WEDNESDAY AND WEDNESDAY NIGHT...AND
AN OVERALL LACK IN KINEMATIC FORCING SHOULD PRESENT DRY CONDITIONS
TO OUR AREA 12Z WEDNESDAY THROUGH 12Z THURSDAY.
AN EASTERLY COMPONENT TO THE LOW LEVEL WIND FIELD AND A SLIGHTLY
COOLER AIRMASS WILL PRESENT COOLER CONDITIONS TO THE AREA TODAY
WHEN COMPARED TO SUNDAY...WITH AFTERNOON HIGHS IN THE LOW TO MID
90S EXPECTED THROUGH MOST LOCATIONS. WARMER WEATHER AHEAD OF THE
APPROACHING LOW LEVEL BAROCLINIC ZONE WILL LIKELY PRESENT
AFTERNOON HIGHS IN THE MID TO UPPER 90S ON TUESDAY. THE COOLER
AIRMASS ON WEDNESDAY WILL LIKELY KEEP AFTERNOON HIGHS IN THE 80S
TO FINISH OUT THE SHORT TERM FORECAST PERIOD. OVERNIGHT LOWS IN
THE 60S WILL REMAIN THE NORM MONDAY NIGHT AND TUESDAY NIGHT...WITH
THE COOLER AIRMASS LIKELY PROMOTING TEMPERATURES IN THE 50S
WEDNESDAY NIGHT INTO THURSDAY MORNING.
.LONG TERM...THURSDAY THROUGH SUNDAY. PRIMARY FORECAST CONCERNS
LIE WITH END OF THE WEEK PRECIPITATION CHANCES...AND TEMPERATURES.
THE START OF THE LONG TERM PERIOD SHOWS MODELS NOT IN TOO BAD OF
AGREEMENT WITH THE PATTERN ACROSS THE CONUS...WHICH REMAINS
ZONAL...SET UP BETWEEN BROAD HIGH PRESSURE EXTENDING ACROSS THE
DESERT SW AND SRN PLAINS...WHILE A LARGE LOW PRESSURE SYSTEM SPINS
OVER CENTRAL CANADA. THROUGH THE END OF THE WORK
WEEK...PRECIPITATION CHANCES CONTINUE ACROSS THE CWA...DRIVEN BY A
COUPLE OF DISTURBANCES ASSOCIATED WITH THAT CANADIAN LOW PRESSURE
SYSTEM. THE FIRST ONE LOOKS TO AFFECT THE AREA MAINLY ON
THURSDAY/THURSDAY NIGHT...ALSO PUSHING A SURFACE BOUNDARY INTO
ROUGHLY THE NORTHERN HALF OF THE CWA DURING THE AFTERNOON HOURS.
THE SECOND DISTURBANCE...DIVING BASICALLY STRAIGHT SOUTH OUT OF
CANADA...AFFECTS THE AREA MAINLY FRIDAY/FRIDAY EVENING. KEPT POPS
CWA-WIDE THURS/THURS NIGHT/FRI...WITH ONLY A FEW LINGERING POPS
INTO FRIDAY NIGHT ACROSS NC KS...AND IF CURRENT MODEL TRENDS
CONTINUES...THOSE FRIDAY EVENING/NIGHT POPS COULD BE REMOVED. AS
MENTIONED...THURSDAY SEE THE INITIAL FRONT MOVE INTO THE CWA...BUT
THAT SECOND DISTURBANCE WILL USHER IN A REINFORCING COLD
FRONT...ACCOMPANIED BY THE COOLER/DRIER AIR FOR FRIDAY. FORECAST
HIGHS FOR THURSDAY SIT IN THE 80S...WHILE FRIDAY IS IN THE MID
70S/LOWER 80S. WILL KEEP THE MENTION OF SOME STRONG/SEVERE
THUNDERSTORMS GOING FOR THIS PERIOD WITH MODELS CONTINUING TO SHOW
THE POTENTIAL FOR DECENT INSTABILITY/SHEAR IN THE AREA.
PLEASANT CONDITIONS ON TAP FOR THE UPCOMING WEEKEND...WITH MODELS
DEPICT DRIER NORTHWESTERLY FLOW SETTING UP IN THE UPPER LEVELS
ACROSS THE CENTRAL PLAINS...SITTING BETWEEN THE TROUGH/LOW OVER
THE GREAT LAKES AND MIDWEST...WHILE RIDGING BUILDS INTO THE
ROCKIES. HIGH PRESSURE LOOKS TO BE THE PRIMARY PLAYER AT THE
SURFACE...BUILDING IN FROM THE NORTHWEST BEHIND THE END OF THE
WORK WEEK FRONTAL PASSAGE. EXPECTING TO SEE PLENTY OF
SUNSHINE...WITH FAIRLY LIGHT WINDS /ESP ON SAT/. THE AREA OF SFC
HIGH PRESSURE LOOKS TO BE CENTERED RIGHT OVER THE CWA ON
SATURDAY...BEFORE SLIDING OFF SLIGHTLY TO THE EAST ON SUNDAY...AND
EXPECTING SATURDAY TO BE A TOUCH COOLER THAN SUNDAY. CURRENT
FORECAST HIGHS ON SATURDAY SIT IN THE MID 70S...WITH SUNDAY
CREEPING UP INTO THE UPPER 70S TO LOWER 80S...BOTH DAYS FEELING
PRETTY NICE WITH DEWPOINTS LOOKING TO BE IN THE 40S FOR MOST
LOCATIONS.
&&
.PREV DISCUSSION... /ISSUED 1222 AM CDT MON SEP 3 2012/
AVIATION...06Z KGRI TAF. VFR CONDITIONS TO CONTINUE THROUGH THE
NEXT 24 HOURS. INCREASING MID TO HIGH LEVEL CLOUDS WILL BE
OBSERVED AT THE TERMINAL DURING THE DAY MONDAY...BUT NOTHING BELOW
10000FT AGL CURRENTLY FORECAST. SURFACE WINDS WILL REMAIN LIGHT
AND VARIABLE THROUGH 14Z...THEN BECOMING MORE ESTABLISHED FROM THE
EAST AT AROUND 12KTS BEFORE ONCE AGAIN BECOMING LIGHT AND VARIABLE
AROUND 02Z. ISOLATED SHOWERS OR THUNDERSTORMS WILL BE POSSIBLE AT
THE TERMINAL THROUGH THE NEXT 24 HOURS...BUT CHANCES OF MEASURABLE
PRECIPITATION ACTUALLY BEING REALIZED AT KGRI ARE TOO LOW FOR
INSERTION INTO THE TAF AT THIS TIME. VISIBILITY RESTRICTIONS ARE
NOT EXPECTED THROUGH THE NEXT 24 HOURS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM/AVIATION...BRYANT
LONG TERM...ADO
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
222 AM EDT MON SEP 3 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE SLOWLY EASTWARD THROUGH THE OHIO VALLEY ON
MONDAY AND TUESDAY. A WEAK COLD FRONT WILL CROSS THE AREA ON
WEDNESDAY...WITH HIGH PRESSURE BUILDING IN FOR THE END OF THE
WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
BROKEN BAND OF SHOWERS ARC FROM NEAR RICHMOND INDIANA...DOWN TO
EAST OF CINCINNATI TO NR JACKSON KY IS FORECAST TO CONTINUE TO
PIVOT N TO NE OVERNIGHT. LATEST RUNS OF THE RAP AND NAM MODELS ARE
SUGGESTING THAT IT WILL WEAKEN/BREAK UP AS THE NIGHT
PROGRESSES...SO TRENDED THE FORECAST THAT WAY. KEPT SOME HIGHER
CHC POPS IN THE S BY 12Z...WITH MAINLY SLIGHT CHC POPS IN THE N.
DIDNT ADJUST LOWS FOR TONIGHT AS THEY LOOK ON TRACK. KEPT THEM IN
THE UPPER 60S TO LOWER 70S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
THE EXPECTED EASTWARD MOVEMENT OF THE WEAKENING SURFACE LOW
APPEARS SLOWER ON THE MODEL RUNS TODAY...NECESSITATING LIKELY POPS
AT ALL LOCATIONS ON MONDAY AFTERNOON. THE ATMOSPHERIC MOISTURE
SITUATION WILL NOT CHANGE MUCH...SO HEAVY RAIN WILL AGAIN BE A
POSSIBILITY.
AS POST-ISAAC DISSOLVES AND BECOMES ABSORBED IN THE MEAN
FLOW...THERE ARE SOME SLIGHT TIMING DISAGREEMENTS IN HOW QUICKLY
THE MOISTURE AND FORCING WILL DEPART THE AREA ON TUESDAY. TAKING A
BLENDED APPROACH TO THE TIMING...IT DOES APPEAR THAT LIKELY POPS
WILL BE WARRANTED IN THE EASTERN CWA AS THE DIURNAL CYCLE TAKES
EFFECT.
TEMP FORECAST CHANGES WERE MINIMAL FOR MONDAY AND MONDAY NIGHT. WITH
GREATER EXPECTED CLEARING IN THE WEST ON TUESDAY...MAX TEMPS HAVE
BEEN INCREASED...ESPECIALLY WEST OF I-75.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
A BLEND OF HPC AND THE 00Z ECMWF WAS USED FOR THE LONG TERM
FORECAST.
THE REMNANTS OF ISAAC SHOULD EVENTUALLY MOVE EAST OF THE REGION
TUESDAY NIGHT WITH DECREASING CHANCES OF PCPN.
FOR WEDNESDAY...REGION WILL BE IN A RELATIVE A LULL. MODELS INDICATE
THAT A S/WV MAY PUSH ACRS THE REGION WEDNESDAY AFTN AND EVENING
AHEAD OF A COLD FRONT. THIS WILL WARRANT LOW CHANCE POPS ATTM.
TEMPERATURES WILL WARM INTO THE MID 80S TO NEAR 90.
A STRONGER S/WV IS FORECAST TO MOVE ACRS THE NRN GREAT LAKES
WEDNESDAY NIGHT AND THURSDAY. THIS WILL PUSH A WEAK COLD FRONT
ACROSS THE AREA. THERE WILL REMAIN A LOW CHANCE OF SHOWERS AND
THUNDERSTORMS UNTIL THIS PASSES.
HIGH PRESSURE WILL BRIEFLY BUILD IN THURSDAY NIGHT INTO THE FIRST
PART OF FRIDAY. WHILE THERE IS SOME DISCREPANCY IN MODEL SOLUTIONS
BY THE END OF THE WEEK...THERE ARE INDICATIONS THAT ANOTHER MORE
VIGOROUS SHORT WAVE WILL AFFECT THE REGION FRIDAY NIGHT AND
SATURDAY. THIS SYSTEM AND ITS ASSOCIATED LOW PRESSURE AND COLD FRONT
WILL HAVE TEMPERATURE IMPLICATIONS DEPENDING ON HOW IT DEVELOPS AND
MOVES ACRS THE OHIO VALLEY.
MODELS INDICATE THAT AFOREMENTIONED UPR LVL ENERGY MAY EVOLVE INTO A
CLOSED LOW OVER THE REGION FOR THE FIRST PART OF NEXT WEEK. THIS MAY
ALLOW A FEW SHOWERS TO LINGER.
TEMPERATURES WILL SHOW A GRADUAL COOLING TREND THROUGH THE PERIOD.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
LOW CIGS WERE DEVELOPING AND MOVING INTO THE KCVG AND KLUK TAF
SITES FOR THE BEGINNING OF THE TAF PERIOD. EXPECT CIGS TO LOWER
THROUGH THE OVERNIGHT TIME FRAME. SOME LIGHT SHOWERS WILL MOVE
ACROSS THE TAF SITES DURING THE OVERNIGHT HOURS. SOME HEAVIER RAIN
WILL MOVE ACROSS THE KCMH AND KLCK TAF SITES. ALTHOUGH THUNDER
CANNOT BE RULED OUT AT KCMH AND KLCK...THE THUNDER CHANCES ARE
MINIMAL AND THEREFORE HAVE LEFT OUT OF THE TAFS AT THIS TIME.
CIGS WILL BEGIN TO IMPROVE THROUGH THE MORNING HOURS WITH SOME OF
THE AREA TAF SITES EXPERIENCING VFR CONDITIONS FOR A TIME DURING
THE AFTERNOON AND EVENING HOURS ON MONDAY. ADDITIONAL SHOWER
ACTIVITY WILL DEVELOP DURING THE DAY. SOME LOCATIONS MAY SEE MVFR
VSBYS WITH SOME OF THE HEAVIER SHOWER ACTIVITY. SOME ISOLATED
THUNDER WILL BE POSSIBLE DURING THE AFTERNOON HOURS ON MONDAY
HOWEVER DUE TO THE ISOLATED NATURE OF THIS THUNDERSTORM ACTIVITY
HAVE AGAIN LEFT THE THUNDER MENTION OUT OF THE TAFS AT THIS TIME.
PRECIPITATION WILL TAPER OFF DURING THE LATE AFTERNOON AND INTO
THE EVENING HOURS ACROSS THE TAF SITES. EXPECT LOW CIGS AND
REDUCED VSBYS TO DEVELOP ONCE AGAIN MONDAY NIGHT ACROSS THE AREA
TAF SITES.
.OUTLOOK...MVFR TO IFR CEILINGS AND VISIBILITIES POSSIBLE MONDAY
NIGHT AND TUESDAY. THUNDERSTORMS ARE POSSIBLE WEDNESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...SITES
SHORT TERM...HATZOS
LONG TERM...HICKMAN
AVIATION...NOVAK
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1238 AM EDT MON SEP 3 2012
.SYNOPSIS...
THE REMNANTS OF ISAAC WILL MOVE EAST ACROSS THE OHIO VALLEY THROUGH
TUESDAY WITH A HUMID AIRMASS AND PERIODS OF HEAVY RAIN. A WEAK FRONT
WILL HELP TO DRY US OUT ON TUESDAY NIGHT WITH A STRONGER COLD
FRONT WITH AN AIRMASS CHANGE PUSHING SOUTH ACROSS THE AREA ON
THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
UPDATED TO SLOW DOWN THE TIMING OF SHOWERS OVER THE EXTREME
SOUTHERN COUNTIES AND ADJUSTED THE LOWS A LITTLE. WATCHING SOME
SHOWERS TO THE SOUTH OF COLUMBUS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/...
LOW SPINNING ACROSS ILLINOIS WILL CONTINUE TO FILL AND DRIFT EAST-
SOUTHEAST OVER THE NEXT TWO DAYS. COVERAGE OF SHOWERS/TS COULD BE
ON THE UPTICK FOR MONDAY. HAVE MAINTAINED SOME OF THE LIKELY POPS
ESPECIALLY ACROSS THE SOUTH AND SOUTHEAST. STUCK WITH SIMILAR
HIGHS FOR TOMORROW. UPPER TROUGH BEGINS TO OPEN UP AND WITH SOME
DIURNAL HEATING TS SHOULD POP UP. WILL HAVE TO CONTINUE THE PRECIP
CHANCES INTO MONDAY NIGHT. AT THIS POINT WE WILL BE GETTING SOME
EXTRA UPPER SUPPORT IN THE FORM OF A SHORTWAVE/JET COMING ACROSS
THE GREAT LAKES. THE COLD FRONT WILL MOVE ACROSS TUESDAY. WE WILL
STILL HAVE TO BE ON THE LOOKOUT FOR HEAVIER RAINFALL ESPECIALLY
LATER MONDAY NIGHT AND TUESDAY WITH BETTER FOCUSING MECHANISMS
LOCALLY. LOCALIZED FLOODING WILL STILL BE A CONCERN THROUGH
TUESDAY.
WEDNESDAY LOOKS LIKE THE FIRST GOOD DRY/IN BETWEEN SYSTEMS DAY.
WEAK HIGH PRESSURE OVER THE AREA AND SOME SUN SHOULD BE ABLE TO
BRING TEMPS UP INTO THE MID 80S...OR MAYBE EVEN SOME UPPER 80S. WE
WILL NOT GET A GOOD AIRMASS CHANGE UNTIL AFTER WEDNESDAY NIGHT
WITH THE NEXT SYSTEM IN THE EXTENDED.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A COLD FRONT WILL MOVE ACROSS THE REGION THURSDAY WITH SOME
SCATTERED SHOWERS AND THUNDERSTORMS ANTICIPATED. THE FRONT SHOULD
CLEAR THE ENTIRE REGION BY THURSDAY EVENING. THIS WILL ALLOW HIGH
PRESSURE TO RETURN FOR FRIDAY. THIS LOOKS TO BE SHORT LIVED AS THE
NEXT TROUGH MOVES INTO THE WESTERN GREAT LAKES ON FRIDAY.
TEMPERATURES WILL BE NEAR TO SLIGHTLY ABOVE SEASONAL AVERAGES ON
THURSDAY. COOLER IN THE WAKE OF THE FRONT FOR FRIDAY INTO SATURDAY
WITH HIGHS GENERALLY IN THE MIDDLE TO UPPER 70S.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
SATELLITE LOOP SHOWS THE CENTER OF THE REMNANTS OF ISAAC OVER SERN
IL AT 23Z WITH RADAR SHOWING CONVECTION FROM CENTRAL INDIANA
THROUGH THE KDAY VICINITY INTO SERN OHIO. MORE CONVECTION IS
MOVING NORTH OUT OF KY. ACROSS NWRN OHIO AND NWRN PA CONDITIONS
RANGE FROM MOSTLY VFR FAR EAST TO VFR/MVFR WEST AND SOUTH.
DEWPOINTS 65 TO 70 ACROSS MUCH OF THE AREA WITH LOWER 70S IN KFDY
AND UPPER 50S KERI. FOLLOWING THE HRRR HIGH RESOLUTION MODEL HAVE
KEPT PRECIP OUT OF THE AREA OVERNIGHT. BEST CHANCES HOWEVER WOULD
BE FROM KFDY TO KMFD IF THE BAND DID MANAGE TO REACH THE AREA.
MAIN CONCERN OF THE OVERNIGHT WOULD BE LOWERING CIGS AND
VISIBILITIES IN FOG AND STRATUS WITH DEEP MOISTURE ACROSS THE
AREA. DID BRING TAFS DOWN THROUGH MVFR AFTER MIDNIGHT TO MVFR/IFR
AROUND SUNRISE. AT KERI...WINDS EXPECTED TO TURN SE OVERNIGHT
WHICH WOULD BRING MORE MOISTURE INTO THE AREA SO DID BRING MVFR
CONDITIONS THERE OVERNIGHT AS WELL. ON MONDAY MODELS SHOW
CIRCULATION MOVING SE IN KY. BEST CHANCE FOR CONVECTION GETTING
INTO THE AREA WOULD BE THE SOUTH CENTRAL COUNTIES OF THE CWA. FOR
NOW BROUGHT VCTS TO THE AREA AT KMFD AND KCAK FOR THE AFTERNOON.
.OUTLOOK...NON VFR POSSIBLE MONDAY NIGHT AND TUESDAY WITH
OVERNIGHT AND EARLY MORNING FOG AS WELL AS SCATTERED TO NUMEROUS
SHOWERS/THUNDERSTORMS.
&&
.MARINE...
WINDS HAVE INCREASED TO AROUND 15 KNOTS FOR THE OPEN WATERS AND A
PORTION OF THE NEARSHORE WATERS FROM CONNEAUT TO RIPLEY. THIS HAS
CAUSED SOME LOCALLY HIGHER WAVES FOR THE ERIE AREA WITH 2 TO 4 FOOT
WAVES A DECENT BET INTO THE EVENING. WINDS SHOULD DECREASE THIS
EVENING WITH WAVES DECREASING.
OTHERWISE WE CONTINUE TO WATCH LOW PRESSURE THAT WILL TRACK ALONG
THE OHIO RIVER VALLEY INTO MONDAY NIGHT. THIS WILL KEEP AN EASTERLY
FLOW ON THE LAKE UNTIL A WEAKENING COLD FRONT PASSES ON TUESDAY.
WINDS WILL SHIFT AROUND TO THE NW AND NORTH WITH THE FRONTAL
PASSAGE. WINDS AT THIS POINT DO NOT LOOK STRONG ENOUGH TO NEED A
SMALL CRAFT ADVISORY.
HIGH PRESSURE WILL TAKE CONTROL OF LAKE ERIE TUESDAY NIGHT INTO
WEDNESDAY. A STRONGER COLD FRONT LOOKS TO ARRIVE ON THURSDAY WITH
SOME GUSTY NW WINDS POSSIBLE. THE STRONGER WINDS MAY NOT ARRIVE
UNTIL THURSDAY NIGHT AS HIGH PRESSURE BUILDS ONTO THE WESTERN END OF
THE LAKE.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...OUDEMAN
NEAR TERM...KIELTYKA
SHORT TERM...OUDEMAN
LONG TERM...MULLEN
AVIATION...TK
MARINE...MULLEN
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
325 AM EDT MON SEP 3 2012
.SYNOPSIS...
THE CENTER OF THE REMNANTS OF ISAAC WILL CONTINUE TO MOVE SLOWLY
EASTWARD ACROSS THE OHIO VALLEY TODAY. MOISTURE OUT AHEAD OF THIS
SYSTEM WILL CONTINUE TO INCREASE ATOP THE WESTERN CAROLINAS AND
NORTHEAST GEORGIA INTO WEDNESDAY BEFORE A WEAK COLD FRONT ARRIVES
FROM THE NORTHWEST FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM EDT...THE REMNANT CIRCULATION FROM ISAAC WAS MOVING
SLOWLY E OVER THE OH VALLEY. AS THE ASSOCIATED UPPER LOW CENTER
CONTINUES TO GRADUALLY FILL AND DRIFT EWD INTO THE APPALACHIANS...
LOBES OF VORTICITY WILL CROSS THE REGION TODAY THROUGH TONIGHT. THE
UPPER LEVEL FORCING WILL NOT BE ESPECIALLY STRONG...BUT IT SHOULD BE
PERSISTENT. MEANWHILE...LOW LEVEL FLOW WILL STRENGTHEN AND BACK
THROUGH THE MORNING HOURS. THE LATEST RUC HAS BACKED OFF ON LOW
LEVEL BULK SHEAR VALUES APPROACHING 30 KT IN THE SW MTNS THIS
MORNING...BUT THE BEST COMBINATION OF FORCING AND SHEAR SHOULD STILL
IMPACT SW SECTIONS TODAY. FORTUNATELY...SFC BASED INSTABILITY SHOULD
BE MORE LIMITED IN THIS AREA. FARTHER EAST...AN INSTABILITY GRADIENT
WILL ONCE AGAIN SET UP THROUGH THE AFTN WITH HIGHER VALUES MAINLY
EAST OF INTERSTATE 77. OVERALL INSTABILITY SHOULD BE A BIT LESS
TODAY THAN YESTERDAY GIVEN THE GREATER CLOUD COVER...BUT IT SHOULD
STILL BE SUFFICIENT FOR NUMEROUS THUNDERSTORM DEVELOPMENT WITH AN
ISOLD SEVERE WIND THREAT. A WEAK TORNADO CANNOT BE COMPLETELY RULED
OUT IN SW SECTIONS TODAY.
THE PERSISTENT SRLY UPSLOPE FLOW INTO THE SRN APPALACHIANS MAY POSE
THE GREATEST HYDRO THREAT TODAY THROUGH TONIGHT. HOWEVER...ISOLD
FLOODING WILL BE POSSIBLE JUST ABOUT ANYWHERE TRAINING CONVECTION
DEVELOPS IN THE MOIST SRLY FLOW. WILL CONTINUE TO MONITOR FOR A
POSSIBLE FLASH FLOOD WATCH AS PRECIPITABLE WATER VALUES SURGE
TO...OR REMAIN ABOVE...2 INCHES IN THE DEEPENING SRLY FLOW AND
EXPANDING WARM CLOUD DEPTH. HOWEVER...1 AND 3 HR FFG VALUES ARE
FAIRLY HIGH MOST AREAS (2 TO 3 INCHES FOR 1 HR...3 TO 4 INCHES FOR 3
HOURS). WILL HOLD OFF ON AN FFA FOR NOW UNTIL WE SEE WHICH AREAS GET
THE MOST WORKED OVER TODAY.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 215 AM EDT MONDAY...THE EXTRATROPICAL CYCLONE ASSOCIATED WITH
THE REMNANTS OF T.C. ISAAC WILL CONTINUE TO FILL DURING THE SHORT
TERM...EVENTUALLY EVOLVING INTO AN ELONGATED SHEAR AXIS. THE SHEAR
AXIS WILL CONTINUE TO WEAKEN AS IT PROGRESS SLOWLY ACROSS THE
EASTERN CONUS...BEFORE FINALLY BEING KICKED OUT BY A STRONG NORTHERN
CONUS/SOUTHERN CANADIAN SHORT WAVE TROUGH LATE IN THE WEEK. THE
UPSHOT OF THIS WILL BE THE CONTINUED PRESENCE OF A PLUME OF
EXTREMELY MOIST TROPICAL AIR OVER THE REGION. PRECIPITABLE WATERS OF
AT LEAST 2 INCHES ARE EXPECTED...WHICH IS AROUND 2 STANDARD
DEVIATIONS ABOVE THE NORM ACCORDING TO A PWAT CLIMATOLOGY FROM NWS/
WFO RAPID CITY. IN ADDITION...FORECAST SOUNDINGS DEPICT EXTREMELY
DEEP WARM CLOUD DEPTHS...UP TO IF NOT EXCEEDING 4 KM (DIFF BETWEEN
THE LCL AND THE FZL). DIURNAL HEATING OF THIS TROPICAL AIR MASS WILL
RESULT IN DEVELOPMENT OF NUMEROUS SHOWERS AND SOME THUNDERSTORMS ON
TUE AND WED. ANY CONVECTIVE CELLS THAT DEVELOP WILL BE EXTREMELY
EFFICIENT RAINFALL PRODUCERS.
OUR SAVING GRACE IS THAT MEAN WINDS IN THE CLOUD-BEARING LAYER ARE
EXPECTED TO BE IN THE 10-15 KT RANGE...SO CELLS SHOULD MOVE ALONG
RELATIVELY QUICKLY. HOWEVER...TRAINING CELLS...AND LOCALIZED FLASH
FLOODING WILL CERTAINLY BE POSSIBLE JUST ABOUT ANYWHERE. ON
TUESDAY...IT APPEARS THAT THE BEST CHANCE FOR EXCESSIVE RAINFALL AND
FLASH FLOODING WILL BE NEAR THE SOUTHERN ESCARPMENT OF THE BLUE
RIDGE...AS MODEL SOLUTIONS DEPICT A MODERATELY STRONG (FOR LATE
SUMMER) SOUTHERLY LOW LEVEL FLOW. ON WEDNESDAY...THE SHEAR AXIS WILL
PUSH INTO THE AREA...AND THE LOW LEVEL REFLECTION OF THIS FEATURE
MAY PROVIDE A FOCUS FOR TRAINING CELLS...OWING TO THE BOUNDARY-
PARALLEL NATURE OF THE MEAN WIND PROFILE. IN ADDITION...ANTECEDENT
CONDITIONS AFTER A COUPLE OF DAYS OF HEAVY RAIN WILL PROBABLY BECOME
CRITICAL IN SOME AREAS BY WEDNESDAY. IT/S JUST IMPOSSIBLE TO SAY
WHERE THESE AREAS WILL BE AT THIS POINT. REGARDLESS...IT IS LIKELY
THAT A FLASH FLOOD WATCH WILL BE ISSUED FOR A PORTION OF THE AREA BY
WEDNESDAY.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 100 AM EDT MONDAY...VERY WEAK SFC RIDGING LOOKS TO BUILD INTO
THE MTNS ON THURSDAY WHILE WEAK SFC BNDRY LINGERS ACRS THE CENTRAL
CAROLINAS. MODEL CONSENSUS IS STILL DISPLACING THE DEEPEST RH EAST
OF THE CWFA AS THE DAY WEARS ON...BUT DEVELOPING INSTABILITY WITHIN
THE UPPER DIFFLUENT FLOW SHOULD BE ENUF TO SUPPORT GOING CHANCE POP
CWFAWIDE. THE CONTINUED INFLUX OF LOWER PWAT VALUES SHOULD BE ABLE
TO LOWER PRECIP CHANCES TO LESS THAN SLIGHT AT SOME POINT THURSDAY
NIGHT.
IT STILL LOOKS LIKE A MOSTLY DRY DAY IS ON TAP FOR FRIDAY WITHIN
THE DEVELOPING WEAK S/WV RIDGING ALOFT BUT THE VERY LOW END DEEP
CONVECTIVE CHANCE WILL BE MAINTAINED ACROSS THE NC MTNS IN THE
AFTERNOON.
WITHIN THE EXPECTED AMPLIFYING PATTERN THIS WEEKEND...ANOTHER
FRONTAL SYSTEM SHOULD AFFECT THE CWFA BUT FOR NOW WILL KEEP THE
INHERITED CLIMO/HPC POPS SATURDAY WITH A LITTLE HIGHER CHANCES
FOR SUNDAY.
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
AT KCLT...THE TERMINAL AREA REMAINS IN A LULL EARLY THIS MORNING AS
OVERNIGHT PIEDMONT CONVECTION IS WELL EAST OF KCLT...AND THE DEEPER
MOISTURE STILL REMAINS WEST OF THE AREA. EXPECT FLOW TO BACK SRLY
THROUGH A DEEP LAYER TODAY AND STRENGTHEN TO BRING MOISTURE BACK
RAPIDLY. THE THICKENING MID AND HIGH CLOUDS SHOULD PERMIT NO WORSE
THAN MVFR FOG AROUND DAYBREAK. PIEDMONT TSTMS ARE EXPECTED AGAIN
THIS AFTERNOON AS WARM ADVECTION FLOW INCREASES. WILL TARGET 20Z TO
00Z AS THE MOST FAVORED PERIOD FOR TSTMS...WITH SHOWERS LIKELY
OUTSIDE OF THAT PERIOD. CIG RESTRICTIONS WILL BE POSSIBLE UNDER ANY
CONVECTION...BUT EXPECT MAINLY VFR CIGS OTHERWISE. THERE WERE SOME
LOW END GUSTS YESTERDAY AND BOUNDARY LAYER WINDS WILL BE A BIT
STRONGER TODAY...SO WILL ADVERTISE G16 KT AFTER 19Z. RESTRICTIONS
WILL LIKELY BECOME MORE PERSISTENT JUST PAST THE CURRENT TAF PERIOD.
ELSEWHERE...IMPROVING SRLY UPSLOPE FLOW AND MOISTURE WILL ALLOW
SHOWERS TO BREAK OUT FIRST AROUND KAVL EARLY THIS MORNING AND SPREAD
EASTWARD THROUGH THE DAY AS THE MOISTURE DEEPENS. ANY IFR CIGS
AROUND DAYBREAK SHOULD BE CONFINED TO KAVL AND POSSIBLY KHKY. VCTS
SHOULD IMPACT KAVL SOONEST THIS MORNING...BUT WILL RESERVE TEMPO
THUNDER FOR MAINLY AFTER 18Z AT THE FOOTHILL TAF SITES. OUTSIDE OF
ANY CONVECTION...EXPECT VFR CIGS TO STEADILY LOWER...WITH MVFR CIGS
LIKELY TOWARD EVENING THROUGHOUT. EXPECT S WINDS AT 10 KT OR LESS.
THERE COULD BE A FEW LOW END GUSTS AT THE SC TAF SITES THIS AFTN.
OUTLOOK...DEEP MOISTURE WILL PERSIST ACROSS THE REGION THROUGH AT
LEAST WEDNESDAY. LOW CLOUD/FOG RESTRICTIONS WILL BECOME INCREASINGLY
WIDESPREAD AND PERSISTENT AS SHOWER COVERAGE REMAINS HIGH TUE INTO
WED. GRADUAL DRYING FROM THE WEST IS POSSIBLE THU...BUT MORE LIKELY
ON FRI.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...CSH
NEAR TERM...HG
SHORT TERM...JDL
LONG TERM...CSH
AVIATION...HG
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
327 AM CDT MON SEP 3 2012
.SHORT TERM...TODAY THROUGH WEDNESDAY
327 AM CDT MON SEP 3 2012
CONCERNS CENTER AROUND RAIN CHANCES THROUGH THE PERIOD/SEVERE
CHANCES TODAY.
BUSY WATER VAPOR LOOP THIS MORNING WITH A MID LEVEL TROUGH MOVING
THROUGH MN AND THEN A MORE VIGOROUS CLOSED LOW/TROUGH MOVING THROUGH
ALBERTA CANADA/MONTANA. AT THE SURFACE...A COLD FRONT EXTENDED FROM
NEAR INTERNATIONAL FALLS TO SAINT CLOUD MN...AND THEN SOUTHWESTWARD
TO SIOUX FALLS SD. RADAR MOSAIC SHOWING BAND OF SCATTERED
SHOWERS/THUNDERSTORMS AHEAD OF THE FRONT FROM NEAR THE ARROWHEAD OF MN
INTO NORTHWEST WI AND EAST CENTRAL MN. RAP SHOWS THIS ACTIVITY WAS
ON THE EASTERN PERIPHERY OF FAIRLY DECENT AXIS OF 850MB MOISTURE
TRANSPORT. OTHERWISE...TEMPERATURES ACROSS THE FORECAST AREA AT 3 AM
WERE HOLDING IN THE UPPER 60S/LOWER 70S WITH DEWPOINTS IN THE MIDDLE
60S.
SUNDAY EVENING MODEL RUNS SHOWING FAIRLY DECENT AGREEMENT THROUGH
THE SHORT TERM PERIOD.
LOOK FOR THE MID-LEVEL SHORTWAVE AND ASSOCIATED SURFACE COLD FRONT
OVER MN TO SINK SLOWLY SOUTHEAST INTO THE AREA TODAY...WHILE
UNDERGOING SOME WEAKENING. RAP/NAM MODELS SHOWING BEST 850MB
MOISTURE TRANSPORT AHEAD OF THE TROUGH/FRONT PUSHING EAST OF THE
AREA BY LATER THIS MORNING. HOWEVER...MODELS FAIRLY PERSISTENT IN
PRODUCING SCATTERED SHOWERS AND THUNDERSTORM TODAY ACROSS THE
AREA...WITH BETTER CHANCES HEADED INTO THE AFTERNOON GIVEN PEAK
HEATING/HIGHER DEW POINT POOLING AND 0-3KM MUCAPE PEAKING IN THE
3000-5000J/KG RANGE WITH DOWNDRAFT CAPE IN THE 1500-2000J/KG RANGE.
UPPER LEVEL DYNAMICS HELP ALSO GIVEN RIGHT ENTRANCE REGION OF 300MB
JET PER THE NAM BY THIS AFTERNOON. MODEL SOUNDINGS SHOW INVERTED-V
AND ALTHOUGH 0-3KM BULK SHEAR FAIRLY LIMITED...DOWNDRAFT CAPE HAS ME
A BIT CONCERNED FOR DAMAGING WIND POTENTIAL. WILL HAVE TO KEEP A
VERY CLOSE EYE ON THINGS TODAY. OTHERWISE...ANOTHER UNSEASONABLY
WARM DAY ON TAP WITH HIGHS PUSHING INTO THE 80S ONCE AGAIN.
LOOKING FOR THE BULK OF THE SHOWERS/THUNDERSTORMS TO MOVE SOUTHEAST
OF THE AREA THIS EVENING...BUT THEN MODELS SHOWING ANOTHER MID-LEVEL
TROUGH PUSHING ACROSS THE PLAINS TOWARD THE AREA AFTER MIDNIGHT WITH
WEAK ISENTROPIC LIFT AND MOISTURE TRANSPORT. KEPT SMALLER 20-30 POP
SHRA/T CHANCE TO COVER THIS WEAKER SIGNAL.
GFS AND NAM HINTING AT SOME SORT OF WEAK TROUGH RIPPLING THROUGH
FAIRLY HIGH-ZONAL FLOW ALOFT ON TUESDAY WITH SOME MINOR TIMING
DIFFERENCES NOTED. GIVEN THIS RATHER NONDESCRIPT SIGNAL...WILL STICK
WITH SLIGHT CHANCE OF SHRA/TS.
A MORE VIGOROUS MID-LEVEL CLOSED LOW SWINGS EAST ACROSS SOUTHERN
CANADA TUESDAY NIGHT/WEDNESDAY WITH TROUGH AXIS AND ASSOCIATED
STRONG SURFACE COLD FRONT SWINGING EAST ACROSS THE AREA. THIS HAS BEEN A
RATHER CONSISTENT SIGNAL THE LAST FEW DAYS NOW...SO FEEL COMFORTABLE
WITH HIGHER-END CHANCE TO LIKELY SHRA/TS. GIVEN TIMING OF THE
FRONTAL PASSAGE THROUGH THE AREA WEDNESDAY MORNING...SEVERE THREAT
LOOKS TO BE SOUTHEAST OF THE AREA DURING THE AFTERNOON.
OTHERWISE...MODEL SOUNDINGS SHOWING GOOD MIXING/DRYING BEHIND THE
FRONT WEDNESDAY AFTERNOON ON BREEZY NORTHWEST WINDS IN THE 15 TO 30
MPH RANGE. TEMPERATURES WILL ALSO RETURN TO NEAR SEASONAL NORMALS IN
THE MID 70S TO LOWER 80S.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
327 AM CDT MON SEP 3 2012
FAIRLY GOOD AGREEMENT BETWEEN THE GFS AND ECMWF IN THE WEDNESDAY
NIGHT THROUGH SATURDAY TIME FRAME. WEDNESDAY NIGHT/THURSDAY LOOK
COOLER AND DRY AS MID/UPPER LEVEL TROUGH SETTLES INTO THE AREA. LOWS
WEDNESDAY NIGHT EXPECTED TO FALL INTO THE UPPER 40S TO LOWER 50S WITH
HIGHS ON THURSDAY IN THE 70S. SHRA/TS CHANCES RETURN TO THE AREA
THURSDAY NIGHT THROUGH FRIDAY NIGHT AS AS ANOTHER MID-LEVEL TROUGH
DROPS THROUGH THE REGION WITH A REINFORCING SHOT OF COOLER AND MORE
AUTUMN-LIKE AIR. EXPECTING HIGHS ON FRIDAY IN THE UPPER 60S TO
MIDDLE 70S WITH LOWS IN THE UPPER 40S TO MIDDLE 50S. SATURDAY
CONTINUES TO BE COOL BUT DRY WITH HIGHS IN THE UPPER 60S AND LOWER
70S AFTER OVERNIGHT LOWS IN THE UPPER 40S TO LOWER 50S. APPEARS
SUNDAY WILL SEE SOME WARMING AS MID-LEVEL HEIGHTS BUILD IN RESPONSE
TO RIDGE BUILDING IN FROM THE PLAINS. LOOK FOR HIGHS IN THE LOWER TO
MIDDLE 70S.
&&
.AVIATION...THROUGH 06Z TUESDAY
1154 PM CDT SUN SEP 2 2012
00Z MPX SOUNDING SHOWS CAPPING INVERSION AROUND 800MB AND THUS
CONVECTION HASNT DEVELOPED AHEAD OF THE COLD FRONT. 03.00Z
ARXLAPS AND 03.01Z HRRR DOES SHOW SOME DEVELOPMENT LATE TONIGHT
AFTER 09Z...BUT KEEPS IT WEST OF THE TAF SITES AND THUS ONLY
EXPECTING SOME MID AND HIGH LEVEL CLOUDS AOA 12K FEET. SOUNDINGS
ALSO SHOWING GRADIENT REMAINING UP...ESPECIALLY JUST ABOVE THE
BOUNDARY LAYER. WINDS HAVE DECOUPLED AT KLSE...BUT BLUFF TOP WINDS
BLOWING AT AROUND 5 TO 10 KNOTS. DID KEEP SOME MVFR VISIBILITIES
IN LATE TONIGHT AS DEW POINT SPREADS ARE AROUND 7 DEGREES CELSIUS
AT 03Z. COLD FRONT PUSHES ACROSS THE AREA MONDAY AFTERNOON. 03.00Z
NAM DOES SHOW CONVECTION DEVELOPING OVER THE AREA...BUT BASED ON
FRONTAL POSITION MAY ONLY AFFECT KLSE. DID CONTINUE THE MENTION OF
THE VCSH AND LATER SHIFTS CAN REFINE. CEILINGS LOOK TO REMAIN IN
THE VFR CATEGORY...BUT CANNOT RULE OUT SOME IFR OR MVFR CEILINGS
IF STORMS IMPACT EITHER OF THE TAF SITES.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
327 AM CDT MON SEP 3 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1154 PM CDT SUN SEP 2 2012
.SHORT TERM...TONIGHT THROUGH WEDNESDAY
239 PM CDT SUN SEP 2 2012
MAIN FORECAST CONCERNS ARE ON PRECIPITATION CHANCES THROUGHOUT AND
ANY SEVERE WEATHER POTENTIAL FOR MONDAY/LABOR DAY.
CURRENTLY AS OF 20Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A DEEP UPPER LOW OVER SASKATCHEWAN....RIDGING OVER THE
WESTERN GREAT LAKES REGION...AND THE REMNANTS OF ISAAC IN SOUTHWEST
INDIANA. WITHIN THE SOUTHWEST FLOW BETWEEN THE UPPER LOW AND THE
RIDGING...A SHORTWAVE WAS PRESENT FROM LAKE WINNIPEG TO CENTRAL
SOUTH DAKOTA. THE COMBINATION OF DPVA AHEAD OF THIS SHORTWAVE AND
LOW TO MID LEVEL MOISTURE TRANSPORT SURGING NORTH HAS KEPT SOME
SHOWERS AND THUNDERSTORMS GOING OVER NORTHWEST MINNESOTA. THIS
MOISTURE TRANSPORT CAN BE SEEN IN SOME OF THE GOES DERIVED
PRECIPITABLE WATER IMAGERY...WHERE VALUES ARE IN THE 1-1.3 INCH
RANGE FROM EASTERN NEBRASKA INTO WESTERN MINNESOTA. ASSOCIATED WITH
THIS SHORTWAVE AT THE SURFACE IS A COLD FRONT THAT STRETCHES FROM
NORTH CENTRAL MINNESOTA BACK INTO SOUTHEAST SOUTH DAKOTA. OVER OUR
AREA...PLENTY OF SUNSHINE CONTINUES...THANKS TO DRY AIR PRESENT AS
SEEN ON THE 12Z MPX SOUNDING. MIXING FROM THE SUN COMBINED WITH
850MB TEMPS AROUND 18C PER 12Z SOUNDINGS ALLOWING TEMPERATURES TO
CLIMB INTO THE LOW TO MID 80S. SOME CUMULUS HAS FORMED OVER THE
SOUTHEAST HALF OF THE AREA...THOUGH...REFLECTIVE OF ISAAC MOISTURE
BEGINNING TO GET PULLED NORTHWEST AHEAD OF THE SHORTWAVE/FRONT. THAT
MOISTURE CAN BE SEEN TOO ON GOES PRECIPITABLE WATER IMAGERY.
TONIGHT AND MONDAY...THE SHORTWAVE SEEN OVER THE DAKOTAS IS PROGGED
TO PUSH EAST-NORTHEAST IN RESPONSE TO THE DEEP UPPER LOW IN CANADA
HEADING EAST. AS THE SHORTWAVE HEADS INTO THE RIDGE OVER THE
FORECAST AREA...IT LOOKS LIKE IT WILL WEAKEN...BUT COME THROUGH
NORTHERN SECTIONS OF THE FORECAST AREA AT A GOOD TIME FOR CONVECTIVE
INITIATION...I.E. MONDAY AFTERNOON. WITH THE SHORTWAVE WEAKENING...
SO DOES THE FRONT ASSOCIATED WITH IT. HOWEVER...ALSO OF INTEREST IS
MOST MODELS SHOWING A SHORTWAVE COMING OUT OF UTAH/COLORADO RIGHT
NOW. THIS SHORTWAVE GETS PICKED UP BY THE SOUTHWEST FLOW AND ENTERS
THE SOUTHERN PORTION OF THE FORECAST AREA DURING THE AFTERNOON. SO
ALTHOUGH THE SURFACE FRONTAL FEATURE IS WEAKENING...THERE ARE A
COUPLE OF AIDES ALOFT FOR CONVECTION. BEFORE DISCUSSING MONDAY
FURTHER...BACK TO TONIGHT. ANTICIPATING CONVECTIVE DEVELOPMENT ALONG
THE FRONT LATE THIS AFTERNOON OR DURING THE EVENING IN WESTERN
MINNESOTA. THIS ACTIVITY SHOULD WEAKEN OVERNIGHT WITH LOSS OF
HEATING...BUT SOME COULD LINGER AND SCRAPE THE NORTHWEST SECTION OF
THE FORECAST AREA VERY LATE IN THE NIGHT. CERTAINLY THE MOISTURE
TRANSPORT THROUGHOUT THE 925-700MB LAYER STAYING FOCUSED UP WELL TO
THE NORTH DOESNT HELP TO MAINTAIN CONVECTION. IT IS ENTIRELY
POSSIBLE MONDAY MORNING THAT NO PRECIPITATION IS AROUND...A BREAK
BETWEEN THE TONIGHT ACTIVITY DIMINISHING AND AFTERNOON ACTIVITY
STARTING UP. FOR THE AFTERNOON...BUILDING INSTABILITY WITH MLCAPES
OF 1000-2000 J/KG COMBINED WITH THE TWO SHORTWAVES SHOULD INITIATE
CONVECTION. IN FACT...THE ONE SHORTWAVE COMING FROM THE SOUTHWEST
MAY END UP HAVING MOST OF THE CONVECTION...AS NOTED BY THE 02.12Z
SPCWRF-NMM...HIRESW-ARW AND NAM. AS SUCH...HAVE INCREASED
PRECIPITATION CHANCES TO 50 PERCENT SOUTH OF I-90. REGARDING SEVERE
RISK...ONLY AREA OF CONCERN IS AHEAD OF THAT SHORTWAVE...WHERE
LOCALIZED 0-6KM SHEAR VALUES JUMP UP TO 25-30KT. OUTSIDE OF
THAT...0-3KM AND 0-6KM SHEAR VALUES ARE GENERALLY BELOW 20 KTS.
THEREFORE...THINKING MOST CONVECTION NORTH OF I-90 SHOULD STAY
SUB-SEVERE WHILE THERE COULD BE A RISK SOUTH OF I-90. FOR
TEMPERATURES...INCREASING SOUTHERLY FLOW AND CLOUDS WILL RESULT IN A
WARMER NIGHT TONIGHT. SOME CLOUDS AROUND ON MONDAY MAKE HIGHS A
LITTLE DIFFICULT...BUT WITH 850MB TEMPS STILL NEAR 18C AND SOME
SUN...HIGHS SHOULD AT LEAST GET BACK UP INTO THE LOW TO EVEN MID 80S.
MONDAY NIGHT AND TUESDAY...A WEST-SOUTHWEST 500MB FLOW CONTINUES...
AHEAD OF WHAT IS FORECAST TO BE A POTENT SHORTWAVE DROPPING DOWN
INTO SOUTH CENTRAL CANADA AND THE NORTHWEST DAKOTAS BY 00Z
WEDNESDAY. THERE ARE NO REAL DISCERNIBLE SHORTWAVES COMING
THROUGH THE FLOW AND IMPACTING THE FORECAST AREA ACCORDING TO THE
MODELS. LOOKING AT MOISTURE TRANSPORT AND ISENTROPIC LIFT
FIELDS...THERE IS NOTHING REALLY TO NOTE EITHER THAT SUGGEST
PRECIPITATION...AT LEAST FROM THE 02.12Z NAM/GFS. THEREFORE...ONCE
WHATEVER CONVECTION OCCURS MONDAY AFTERNOON PUSHES OFF TO THE
EAST...LIKELY EARLY IN THE EVENING...DRY CONDITIONS COULD OCCUR
RIGHT THROUGH TUESDAY. THIS IS A DEFINITE CHANGE FROM PREVIOUS
MODEL RUNS...EVEN THE 02.00Z ECMWF...WHICH HAD SOME BETTER
MOISTURE TRANSPORT AHEAD OF THAT POTENT SHORTWAVE COMING DOWN TO
INITIATE CONVECTION. FOR NOW WILL LOWER PRECIPITATION CHANCES INTO
THE 15-25 PERCENT RANGE...BUT FUTURE FORECASTS MAY BE ABLE TO PULL
THESE CHANCES ENTIRELY IF TRENDS CONTINUE. ANOTHER ITEM TO WATCH
IS FOG TUESDAY MORNING. IF SKIES CAN CLEAR OUT...DECOUPLING OF
WINDS AND ANY RAIN FROM MONDAY WOULD LEAD TO FOG DEVELOPMENT. DUE
TO UNCERTAINTY ON CLOUDS...HAVE LEFT OUT FOG. DESPITE THE
SHORTWAVE PASSAGE MONDAY EVENING...850MB TEMPS STAY WARM IN THE
18-20C RANGE THROUGH TUESDAY. IN ADDITION... DEWPOINTS DO NOT LOOK
TO DROP MUCH IF AT ALL. THEREFORE... ANTICIPATING SIMILAR LOW AND
HIGH TEMPERATURES TO TONIGHT AND MONDAY.
TUESDAY NIGHT AND WEDNESDAY...THAT POTENT SHORTWAVE TROUGH COMING
INTO THE NORTHWEST DAKOTAS LATE TUESDAY IS WELL AGREED UPON BY
MODELS TO MOVE OVER MINNESOTA BY 12Z WEDNESDAY...THEN CONTINUE ITS
FAST MOTION EAST AND REACH WESTERN LOWER MICHIGAN BY 00Z THURSDAY.
PRETTY STRONG FORCING THIS TROUGH...NOTED IN 500-300MB PV
FIELDS...THOUGH MOST OF IT STAYS NORTH OF THE FORECAST AREA. THERE
IS SOME MOISTURE TRANSPORT AND ISENTROPIC LIFT ACCOMPANYING THE
TROUGH...SO WITH THE WEAK HEIGHT FALLS IN OUR AREA WE SHOULD SEE
SOME PRECIPITATION MOVE THROUGH. MOST LIKELY TIME PERIOD APPEARS TO
OCCUR BETWEEN 06Z-18Z WEDNESDAY. PREVIOUS FORECAST PRECIPITATION
CHANCES REFLECT THIS WELL. STRONG ISENTROPIC DESCENT AND SUBSIDENCE
BEHIND THE TROUGH WILL ALLOW FOR DRYING AND CLEARING CONDITIONS
AFTER 18Z WEDNESDAY. THEREFORE...HAVE DRIED OUT THE FORECAST AREA
FOR THE AFTERNOON. NOTE...IT COULD ALSO BE PRETTY BREEZY IN THE
AFTERNOON AS PRESSURE GRADIENT BRIEFLY TIGHTENS...DEEP MIXING AND
COLD ADVECTION OCCUR. REGARDING TEMPERATURES...850MB TEMPS HOLD
BETWEEN 18-20C TUESDAY NIGHT...BUT ONCE THE FRONT MOVES THROUGH WITH
THE SHORTWAVE WEDNESDAY MORNING...THESE TEMPS FALL TO 10-12C BY 00Z
THURSDAY. STILL...HIGHS ON WEDNESDAY SHOULD BE ABLE TO TOP OUT IN
THE MID 70S TO LOW 80S WITH THE SUN IN THE AFTERNOON. WARM NIGHT
LIKELY TUESDAY NIGHT AHEAD OF THE FRONT AND RELATIVELY HIGH
DEWPOINTS.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
239 PM CDT SUN SEP 2 2012
SURPRISINGLY...THE 02.12Z ECMWF/GFS/CANADIAN AND GFS ENSEMBLES ARE
ALL IN REALLY GOOD AGREEMENT WITH THE UPPER AIR AND SURFACE PATTERNS
THROUGH SATURDAY. SOME DIFFERENCES START TO SHOW UP ON SUNDAY...BUT
GIVEN THE AMPLIFICATION FORECAST TO OCCUR...IT IS SURPRISING TO SEE
THE GOOD AGREEMENT. THE LONG TERM PERIOD STARTS OFF WITH UPPER
TROUGHING OVER MUCH OF CENTRAL CANADA WITH A POTENT SHORTWAVE
DROPPING DOWN THROUGH ALBERTA. THIS SHORTWAVE ENDS UP CARVING OUT A
FAIRLY DEEP TROUGH AS IT DIGS SOUTHEAST...REACHING THE OHIO VALLEY
SATURDAY MORNING. AS THIS SHORTWAVE DIGS...A FRONTOGENESIS ZONE
LOOKS TO FORM ACROSS THE FORECAST AREA. THIS APPEARS TO OCCUR
THURSDAY NIGHT AND LASTS THROUGH FRIDAY NIGHT. OVERALL...THE BEST
MOISTURE AND FRONTOGENESIS FORCING STAYS SOUTH...THEREFORE
PRECIPITATION CHANCES ARE ONLY IN THE 20-30 RANGE. ON SATURDAY...
BOTH THE 02.00Z AND 02.12Z ECMWF END UP DEVELOPING A RELATIVELY
STRONG SURFACE LOW IN INDIANA...PARTIALLY CAUSED BY THE UPPER TROUGH
BEGINNING TO CLOSE OFF. THE 02.00Z ECMWF HAD DEFORMATION SHOWERS
INTO THE SOUTHEASTERN HALF OF THE FORECAST AREA FOR SATURDAY.
HOWEVER...THE NEW 02.12Z ECMWF HAS SHOVED THEM OFF TO THE EAST. FOR
NOW...JUST PLACED A 20 PERCENT CHANCE IN THE AREA AROUND GRANT
COUNTY. THE GFS AND CANADIAN ARE MOSTLY DRY. THE REST OF THE WEEKEND
AND GOING INTO EARLY NEXT WEEK WILL ALL HINGE ON WHAT HAPPENS WITH
THE UPPER TROUGH/LOW. THE NEW 02.12Z ECMWF KEEPS IT OVER
INDIANA...LIKE SOME OF THE 02.12Z GFS ENSEMBLES. THE 02.12Z GFS HAS
IT MORE PROGRESSIVE. EITHER SOLUTION LOOKS DRY FOR THE FORECAST
AREA...BUT CLOUDS AND TEMPERATURES WOULD BE GREATLY AFFECTED...WITH
THE FARTHER WEST SOLUTION HOLDING MORE CLOUDS AND COOLER AIR IN THE
FORECAST AREA. SOME OF THE MOVEMENT OF THE UPPER TROUGH/LOW WILL
DEPEND ON TROPICAL STORM LESLIE WHICH IS FORECAST TO MOVE THROUGH
THE WESTERN ATLANTIC AND STRENGTHEN...LIKELY BLOCKING UP THE FLOW.
REGARDING TEMPERATURES...THEY WILL BE ON THE COOL DOWN AS THE UPPER
TROUGH FORMS. 850MB TEMPS FALL FROM THE 10-12C ON THURSDAY TO 6-8C
ON SATURDAY. AS SUCH...HIGHS ARE ONLY FORECAST TO PERHAPS REACH 70
ON SATURDAY. SATURDAY NIGHT COULD BE QUITE COOL...DEPENDING ON
CLOUDS...WITH HIGH PRESSURE POSSIBLY MOVING IN AT THE SURFACE FROM
THE NORTHWEST. SOME SLIGHT REBOUND IN TEMPERATURES ARE ANTICIPATED
ON SUNDAY.
&&
.AVIATION...THROUGH 06Z TUESDAY
1154 PM CDT SUN SEP 2 2012
00Z MPX SOUNDING SHOWS CAPPING INVERSION AROUND 800MB AND THUS
CONVECTION HASNT DEVELOPED AHEAD OF THE COLD FRONT. 03.00Z
ARXLAPS AND 03.01Z HRRR DOES SHOW SOME DEVELOPMENT LATE TONIGHT
AFTER 09Z...BUT KEEPS IT WEST OF THE TAF SITES AND THUS ONLY
EXPECTING SOME MID AND HIGH LEVEL CLOUDS AOA 12K FEET. SOUNDINGS
ALSO SHOWING GRADIENT REMAINING UP...ESPECIALLY JUST ABOVE THE
BOUNDARY LAYER. WINDS HAVE DECOUPLED AT KLSE...BUT BLUFF TOP WINDS
BLOWING AT AROUND 5 TO 10 KNOTS. DID KEEP SOME MVFR VISIBILITIES
IN LATE TONIGHT AS DEW POINT SPREADS ARE AROUND 7 DEGREES CELSIUS
AT 03Z. COLD FRONT PUSHES ACROSS THE AREA MONDAY AFTERNOON. 03.00Z
NAM DOES SHOW CONVECTION DEVELOPING OVER THE AREA...BUT BASED ON
FRONTAL POSITION MAY ONLY AFFECT KLSE. DID CONTINUE THE MENTION OF
THE VCSH AND LATER SHIFTS CAN REFINE. CEILINGS LOOK TO REMAIN IN
THE VFR CATEGORY...BUT CANNOT RULE OUT SOME IFR OR MVFR CEILINGS
IF STORMS IMPACT EITHER OF THE TAF SITES.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
239 PM CDT SUN SEP 2 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS PUEBLO CO
431 AM MDT MON SEP 3 2012
.SHORT TERM...
(TODAY AND TONIGHT)
RADAR IS STILL PICKING UP SOME ECHOES OVR THE FORECAST AREA...BUT
COVERAGE IS SPOTTY. WV SATELLITE IMAGERY SHOWING A PLUME OF
MSTR ACRS THE STATE THIS MORNING. MODELS SHOW DRIER AIR WORKING
INTO THE AREA FROM THE WEST...BUT REMAINING OVR ERN AREAS. AS A
RESULT...THE FORECAST MODELS HAVE LITTLE IN THE WAY OF PCPN OVR THE
CONTDVD TODAY. HOWEVER...THERE MAY STILL BE ENOUGH RESIDUAL MSTR TO
KEEP SOME ISOLD POPS IN THE FORECAST FOR THAT AREA. OVR THE ERN MTS
AND PLAINS...THE 4KM WRF HAS SOME VERY SPOTTY PCPN OCCURRING THIS
AFTERNOON AND EVENING WITH THE BEST CHANCES BEING ALONG THE SRN
BORDER. THE HRRR IS VERY SIMILAR TO THE 4KM WRF. THE NAM ON THE
OTHER HAND HAS SOME LIGHT PCPN BEING POSSIBLE MOST LOCATIONS OF THE
ERN MTS AND PLAINS. WITH THE MST PLUME STILL EXPECTED TO BE IN
PLACE...WL GO WITH GENERALLY ISOLD POPS ACRS MUCH OF THE SERN
PLAINS. MOST AREAS WILL AGAIN SEE HIGH TEMPS THAT ARE 5-10 DEGREES
ABOVE AVERAGE.
TONIGHT THE MSTR PLUME CONTINUE TO MOVE EAST...BUT CONTINUES TO
LINGER OVR THE FAR SERN AREAS. BY MIDNIGHT MOST AREAS SHOULD SEE AN
END TO THE PCPN...BUT THE MODELS DO CONTINUE TO HANG ON TO SOME PCPN
INTO THE LATE NIGHT HOURS OVR THE FAR SERN PLAINS.
.LONG TERM...
(TUESDAY THROUGH SUNDAY)
.TUESDAY...TROUGH MOVES ACROSS THE NORTHERN ROCKIES WITH COLORADO
BEING ON THE SOUTHERN EDGE OF THE TROUGH. MAIN FORECAST CHALLENGE WILL
BE THE AMOUNT OF LOW LEVEL MOISTURE ON THE PLAINS. LATEST NAM AND
GFS HAVE DEW POINTS IN THE 50S TO LOWER 60S ON THE PLAINS TUESDAY
AFTERNOON. MODELS HAVE BEEN PLAGUED BY OVER-FORECASTING DEW POINTS
DURING THE ENTIRE SUMMER...AND HAVE DEW POINTS IN THE 40S TO LOWER
50S IN THE GRIDS. BELIEVE HIGHEST DEW POINTS WILL CLOSE TO THE NEW
MEXICO BORDER WHERE GRIDS HAVE ISOLATED TO SCATTERED POPS.
OTHERWISE...ONLY HAVE SILENT POPS FOR THE REMAINDER OF THE PLAINS.
IN THE MOUNTAINS...DRIER AIR WILL MOVE INTO THE REGION AND HAVE
POPS OVER THE SOUTHERN MOUNTAINS. A COLD FRONT WILL MOVE SOUTHWARD
ACROSS THE PLAINS TUESDAY NIGHT. WITH SOME LOW LEVEL MOISTURE
REMAINING OVER THE SOUTHEAST PORTION OF THE PLAINS...A STORM OR TWO
COULD DEVELOP ALONG THE FRONT...AND MAINTAINED ISOLATED POPS
OVERNIGHT OVER PORTIONS OF THE PLAINS.
.WEDNESDAY...COLD FRONT WILL MOVE SOUTH OF THE STATE BY THE
AFTERNOON...WITH EASTERLY FLOW POOLING LOW LEVEL MOISTURE MOSTLY
OVER NORTHERN NEW MEXICO. SOME OF THE GUIDANCE HAS ENOUGH MOISTURE
REMAINING OVER SOUTHERN COLORADO FOR A FEW AFTERNOON AND EARLY
EVENING STORMS. DECIDED TO MAINTAIN SOME ISOLATED POPS IN THIS
REGION...BUT HEAVIER PRECIPITATION WILL STAY TO THE SOUTH OF THE
STATE. TEMPERATURES ON THE PLAINS WILL COOL TO NEAR NORMAL BEHIND
THE FRONT.
.THURSDAY...A WEAK DISTURBANCE WILL MOVE ACROSS THE REGION WITH
LOW LEVEL DRYING OVER THE INTERSTATE 25 CORRIDOR. GFS CONTINUES TO
BE MUCH TOO HIGH WITH SURFACE DEW POINTS NEAR THE KANSAS
BORDER...WITH DEW POINTS IN THE LOWER 60S AND CAPES AROUND 1500
J/KG. GRIDS HAVE DEW POINTS NEAR THE KANSAS BORDER IN THE MID TO
UPPER 40S...AND ONLY HAVE ISOLATED POPS NEAR THE KANSAS BORDER.
THE PASSING DISTURBANCE SHOULD HELP FIRE CONVECTION OVER THE
MOUNTAINS...FOR SOME AFTERNOON AND EARLY EVENING STORMS.
..FRIDAY THROUGH SUNDAY...A TROUGH MOVES SOUTHEAST OUT OF CANADA AND
INTO THE HIGH PLAINS FRIDAY AND FRIDAY NIGHT. A SHARP COLD FRONT
WILL MOVE SOUTHWARD ACROSS THE PLAINS ON FRIDAY. GFS HAS
WIDESPREAD PRECIPITATION OVER THE EASTERN PLAINS AND INTERSTATE 25
CORRIDOR BEHIND THE FRONT AS SYNOPTIC SCALE LIFT AHEAD OF THE
TROUGH PASSES OVER THE MOIST LOW LEVEL AIR MASS. GFS DEW POINTS ON
FRIDAY ARE IN THE UPPER 50S TO LOWER 60S ON THE PLAINS. ONCE
AGAIN...BELIEVE DEW POINTS ARE MUCH TOO HIGH. EC DEW POINTS ARE IN
THE 40S...WHICH IS MORE REASONABLE. HAVE GENERALLY ISOLATED POPS
ON THE PLAINS AND INTERSTATE 25 CORRIDOR ON FRIDAY TO ACCOUNT FOR
SOME SHOWERS. LOW LEVEL AIR MASS BEHIND THE FRONT WILL BE COOL AND
LACK OF LOW LEVEL MOISTURE WILL RESULT IN A GENERALLY STABLE AIR MASS.
COOL LOW LEVEL AIR MASS REMAINS ON THE PLAINS SATURDAY WITH THE
ATMOSPHERE REMAINING CAPPED. BY SUNDAY...THE COOL AIR MASS MOVE TO
THE EAST WITH WARMER TEMPERATURES. MOISTURE LOOKS TO BE LIMITED
WITH ONLY SILENT POPS. --PGW--
&&
.AVIATION...
VFR CONDITIONS ARE EXPECTED AT THE TAF SITES FOR THE NEXT 24 HOURS.
SOME SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP TODAY...BUT
MAY BE FAIRLY SPOTTY NR THE TAF SITES. KCOS WL PROBABLY HAVE THE
BEST CHANCE OF SEEING SOME SHOWERS OR THUNDERSTORMS IN THE VCNTY.
HOWEVER...CONFIDENCE IS TOO LOW AT THIS TIME TO INCLUDE ANY MENTION
OF TSRA IN THE TAFS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
28/06
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1032 AM EDT MON SEP 3 2012
.SYNOPSIS...
HIGH PRESSURE OVER THE REGION WILL GIVE WAY TO THE REMNANTS OF
ISAAC AS THE CIRCULATION PUSHES EAST INTO THE TENNESSEE VALLEY.
ATMOSPHERIC MOISTURE WILL BE INCREASING AND SO WILL THE CHANCES OF
RAIN ACROSS THE AREA THROUGH MID WEEK. A FRONT WILL PUSH THROUGH
BY THURSDAY...BEFORE YET ANOTHER UPPER DISTURBANCE APPROACHES FOR
THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
THIS MORNING...UPPER LOW CONTAINING REMNANTS OF ISAAC STILL TO
THE WEST. BOTH NAM20 AND RUC13 SHOW UPPER RIDGING WITH NVA OVER
REGION AHEAD OF UPPER SYSTEM. A FEW SHOWERS HAVE DEVELOPED IN
SOUTHEAST GEORGIA AS UPPER RIDGE CONTINUES TO WEAKEN BUT PRECIP
SHOULD BE SLOW TO MOVE INTO AREA DURING THE LATE MORNING AND EARLY
AFTERNOON HOURS. HAVE A 20 POP CENTRAL AND WEST PORTION OF CAE CWA
LATE THIS MORNING INTO EARLY AFTERNOON. JUST 10 PERCENT EAST PART
BUT INCREASE TO 30 PERCENT CHANCE BY EARLY AFTERNOON.
THIS AFTERNOON...THE REMNANTS OF ISAAC WILL DRIFT SOUTHEASTWARD
TOWARDS THE AREA TODAY BUT BECOME LESS DEFINED AS THE UPPER LOW
SHEARS OUT AND BECOMES A WEAK OPEN WAVE BY TONIGHT. ATMOSPHERIC
MOISTURE IS ALREADY QUITE HIGH WITH PWATS CLOSE TO 2 INCHES AS
NOTED ON THE 06Z LAPS SOUNDING AND THESE VALUES WILL INCREASE
FURTHER BY THIS AFTERNOON. MODEL GUIDANCE SUGGESTS SOME UPPER
ENERGY ROTATING AROUND THE CIRCULATION WILL MOVE THROUGH THE
UPSTATE DURING PEAK HEATING AND IS LIKELY TO ORGANIZE SOME
CONVECTION WHICH WILL IMPACT THE WESTERN PORTIONS OF THE FORECAST
AREA.
HI-RES WRF IS IN LINE WITH OPERATIONAL MODELS IN SHOWING A LINE OF
CONVECTION DEVELOPING JUST WEST OF THE FORECAST AREA AND PUSHING
SLOWLY EASTWARD INTO THE WESTERN MIDLANDS AND CSRA LATE AFTERNOON
AND EVENING. DESPITE THE MOS GUIDANCE SHOWING LOW CHANCE POPS TODAY
AND TONIGHT HAVE OPTED TO MAINTAIN PERSISTENCE WITH THE POP FORECAST
AND HOLD LIKELY POPS WESTERN MIDLANDS WITH A GRADIENT TO CHANCE
EASTWARD ACROSS THE FORECAST AREA.
SPC HAS CAE FORECAST AREA IN A SEE TEXT. MODERATE TO STRONG
AFTERNOON INSTABILITY. LIS -4. CAPES AROUND 2000 J/KG BUT WILL
HAVE TO OVERCOME A MID LEVEL CAP. HOWEVER...PULSE STORMS MAY
BECOME STRONG AND APPROACH SEVERE LIMITS IF THERE IS A HIGH
REFLECTIVITY ELEVATED CORE PRESENT IN ANY OF THE STORMS. THE
VIL OF THE DAY IS 69.
TONIGHT...PRECIPITATION IS LIKELY TO LINGER INTO THE OVERNIGHT
HOURS. SEVERE THREAT LOOKS MINIMAL GIVEN A NEARLY MOIST ADIABATIC
SOUNDING PROFILE WITH A WARM CLOUD LAYER DEPTH OVER 10000 FT...AND
THINK HEAVY RAIN FROM TRAINING STORMS COULD BE MORE OF AN ISSUE
THROUGH TONIGHT. TEMPERATURES TODAY WILL AGAIN BE WARM IN THE
LOWER 90S TO AROUND 90 AND BE DEPENDENT ON CLOUD COVER. LOWS
TONIGHT WILL BE LIMITED BY CONVECTIVE DEBRIS CLOUDS AND SHOULD BE
IN THE 70S.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
THE REMNANTS OF ISAAC FURTHER SHEAR AND THE PLUME OF TROPICAL
MOISTURE BECOMES ELONGATED FROM THE GULF COAST NORTHEASTWARD ALONG
THE APPALACHIANS INTO NEW ENGLAND BY TUESDAY NIGHT. THETA-E
MOISTURE TRANSPORT WILL INCREASE OVER THE UPSTATE AND WESTERN
MIDLANDS AND THE INTERACTION WITH DAYTIME HEATING SHOULD YIELD
ANOTHER ROUND OF DIURNAL DEEP MOIST CONVECTION WITHIN A MOIST
ADIABATIC ENVIRONMENT WITH PWATS EXCEEDING 2 INCHES...CLOSE TO 150
PERCENT OF NORMAL. WILL CONTINUE WITH A GRADIENT IN POPS FROM WEST
TO EAST RANGING FROM HIGH CHANCE WESTERN MIDLANDS AND CSRA TO LOW
CHANCE EASTERN MIDLANDS. CHANCES DECREASE DURING THE OVERNIGHT
PERIOD TUESDAY NIGHT...ESPECIALLY IN THE EASTERN PART OF THE
FORECAST AREA WITH THE LOSS OF DAYTIME HEATING. TEMPERATURES SHOULD
BE COOLER ON TUESDAY IN THE MID TO UPPER 80S DUE TO EXTENSIVE CLOUD
COVER IN THE TROPICAL AIRMASS.
ON WEDNESDAY...A WEAK FRONTAL BOUNDARY WILL PUSH TOWARDS THE
FORECAST AREA AND THE AXIS OF DEEP LAYER MOISTURE...LEFTOVER FROM
THE REMNANTS OF ISAAC ALSO SHIFTS TO THE EAST. OPERATIONAL MODELS
DIFFER IN THE TIMING OF THE FRONT PUSHING THROUGH THE AREA...WRF
BEING FASTER AND GFS SLOWER. NEVERTHELESS...WILL AGAIN NEED TO
CARRY MID CHANCE POPS WITH ABUNDANT DEEP LAYER MOISTURE
PRESENT...PWATS CONTINUING OVER 2 INCHES AND MODERATE INSTABILITY.
THE HEAVY RAIN THREAT WILL ALSO CONTINUE THROUGH MID WEEK RESULTING
FROM THE TRAINING OF STORMS WITH HIGH LIQUID WATER CONTENT.
TEMPERATURES WILL REMAIN WARM IN THE MID TO UPPER 80S FOR HIGHS AND
LOWS IN THE 70S.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
LITTLE CHANGE IN THINKING DURING THIS PERIOD. MEDIUM RANGE GUIDANCE
IN REASONABLE AGREEMENT WITH PUSHING A WEAK BOUNDARY THROUGH THE
AREA OR HAVING THE FRONT BECOME DIFFUSE OVER THE AREA THURSDAY WITH
A BREAK IN THE ACTIVE WEATHER FRIDAY. TEMPERATURES WILL REBOUND
BACK TO HIGHS AROUND 90 FOR FRIDAY WITH LOWS FALLING INTO THE UPPER
60S ACROSS MOST OF THE FORECAST AREA AS SOME DRIER AIR WORKS IN FROM
THE NORTHWEST.
BOTH OPERATIONAL RUNS OF THE GFS/ECMWF SHOWING A DYNAMIC UPPER
TROUGH DIGGING ACROSS THE GREAT LAKES AND MIDWESTERN STATES ON
SATURDAY AND CLOSING OFF AN UPPER LOW OVER THE WESTERN OHIO VALLEY
BY SUNDAY. STRONG JET ENERGY ROTATING THROUGH THE BASE OF THE UPPER
TROUGH SHOULD BRING INCREASED DYNAMICS TOWARDS THE FORECAST AREA BY
SUNDAY AND RESULT IN INCREASED CHANCES FOR PRECIPITATION.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
SCATTERED MID LEVEL CLOUDS STILL LINGERING INTO THE LATE MORNING
HOURS AS LEFTOVER CONVECTIVE DEBRIS CLOUDS WERE OVER AREA THIS
MORNING. OTHERWISE...MOISTURE WILL ADVECT INTO THE FORECAST AREA
AHEAD OF THE TROUGH SLOWLY MOVING INTO THE AREA FROM THE WEST.
EXPECT HEATING AND MIXING WILL HELP CAUSE MAINLY VFR CEILINGS
TODAY INTO THE EVENING. THIS IS SUPPORTED BY MOST OF THE GFS AND
NAM MOS. HOWEVER...RESTRICTIONS WILL OCCUR IN SCATTERED SHOWERS
AND THUNDERSTORMS BUT THIS WAS NOT INCLUDED IN THE TERMINAL
FORECASTS BECAUSE OF TIMING UNCERTAINTY AT THIS TIME. INCREASING
LOW-LEVEL MOISTURE AND DIURNAL COOLING WILL LIKELY RESULT IN MVFR
OR IFR CEILINGS AND VISIBILITIES DEVELOPING LATE TONIGHT.
EXTENDED AVIATION OUTLOOK...EXPECT MAINLY LATE NIGHT AND EARLY
MORNING FOG AND STRATUS...AND SCATTERED AFTERNOON THUNDERSTORMS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
07
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1039 AM CDT MON SEP 3 2012
.DISCUSSION...
ISSUED 1039 AM CDT MON SEP 3 2012
15Z/10 AM SURFACE CHART SHOWS 1009MB LOW CENTERED NEAR KEVV...WITH
CLOUD SHIELD EXTENDING ACROSS MUCH OF CENTRAL AND SOUTHEAST ILLINOIS.
FURTHER WEST...ENOUGH SUBSIDENCE IS OCCURRING ON THE BACK SIDE OF
THE SYSTEM TO ALLOW SKIES TO BECOME PARTLY TO MOSTLY SUNNY ALONG
AND WEST OF I-55. WITH ONLY VERY SLOW EASTWARD MOVEMENT...THINK
CLOUDS WILL PERSIST ACROSS THE E/SE KILX CWA THROUGH THE AFTERNOON.
12Z HRRR SUGGESTS A FEW SHOWERS MAY DEVELOP ACROSS THIS AREA AS
WELL...HOWEVER AREAL COVERAGE WILL BE MINIMAL. HAVE UPDATED
FORECAST TO REMOVE MENTION OF THUNDER...OPTING INSTEAD TO GO WITH
ISOLATED TO SCATTERED LIGHT SHOWERS ALONG AND EAST OF I-57. HIGH
TEMP FORECAST APPEARS TO BE ON TRACK...WITH COOLEST READINGS IN
THE LOWER TO MIDDLE 80S ACROSS THE CLOUD-COVERED EAST/SOUTHEAST
AND UPPER 80S FURTHER WEST. ZONE UPDATE HAS ALREADY BEEN ISSUED.
BARNES
&&
.AVIATION...
ISSUED 630 AM CDT MON SEP 3 2012
COVERAGE OF IFR/MVFR CIGS AND FOG THIS MORNING THE MAIN FORECAST
CHALLENGE. WEAK LOW PRESSURE TO OUR SOUTHEAST WILL CONTINUE TO
SLOWLY MOVE AWAY FROM THE MIDWEST TODAY. OUR AREA WILL STILL BE
UNDER THE INFLUENCE OF SOME WEAK CYCLONIC FLOW AND ABUNDANT LOW
LEVEL MOISTURE LEFT OVER FROM THE SYSTEM RESULTING IN THE LOWER
CLOUDS AND FOG THIS MORNING...AND THEN AT LEAST SOME BKN MVFR CIGS
THIS AFTN. ISOLATED SHOWERS WILL BE POSSIBLE AT DEC AND CMI MAINLY
THIS AFTN SO WILL COVER THAT WITH A VCSH IN BOTH LOCATIONS.
SETUP APPEARS TO BE MORE FAVORABLE FOR FOG LATE TONIGHT AS WEAK
HIGH PRESSURE SETTLES INTO THE AREA BRINGING LIGHT WINDS AND CLEAR
SKIES...AT LEAST TO START THE EVENING OUT. HOWEVER...WITH THE
ABUNDANT LOW LEVEL MOISTURE AND LIGHT WIND FLOW...IT SEEMS THAT
FOG IS A DISTINCT POSSIBILITY OVERNIGHT. WILL BRING IN THE LOWER
VSBYS/CIGS AFTR 05Z MOST AREAS. SFC WINDS WILL BE OUT OF THE NE
TODAY AT AROUND 10 KTS WITH A FEW GUSTS UP TO 20 KTS POSSIBLE BY
LATE MORNING INTO THE AFTN HOURS. LIGHT NNE WINDS ARE EXPECTED
TONIGHT.
SMITH
&&
.PREV DISCUSSION...
ISSUED 330 AM CDT MON SEP 3 2012
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
1008 MB LOW PRESSURE (REMNANTS OF ISAAC) WAS OVER FAR SE IL
BETWEEN LAWRENCEVILLE AND EVANSVILLE AND CONTINUED TO BRING
LOW CLOUDS TO AREAS FROM I-55 SE EARLY THIS MORNING WHILE NEARLY
CLEAR SKIES OVER THE IL RIVER VALLEY WITH A LIGHT FOG SO FAR.
GALESBURG VSBY WAS DOWN TO 2 MILES. HUMID AIRMASS LINGERS OVER
CENTRAL/SE IL WITH DEWPOINTS STILL IN THE LOWER 70S...EXCEPT 65F
AT GALESBURG. RADAR MOSAIC SHOWS MOST LIGHT SHOWERS HAVE
TEMPORARILY ENDED OVER CENTRAL/SE IL EARLY THIS MORNING...THOUGH
COULD BE A FEW SPRINKLES/DRIZZLE AROUND IN THE LOW CLOUDS FROM I-55
SE.
MODELS CONTINUE SLOW DRIFT OF LOW PRESSURE FROM FAR SE IL INTO
WESTERN KY TODAY AND STILL CLOSE ENOUGH TO BRING A CHANCE OF
SHOWERS OVER EASTERN IL LATER THIS MORNING AND AFTERNOON AND
PERHAPS AN ISOLATED THUNDERSTORMS IN SE IL THIS AFTERNOON. MORE
LOW CLOUDS LINGER OVER EASTERN IL AS WELL AND KEEP TEMPS A BIT
COOLER THERE. HIGHS IN THE MID 80S TO UPPER 80S WITH WARMER
READINGS WEST WHERE MORE SUNSHINE EXPECTED. WILL MENTION PATCHY
FOG FROM I-55 WEST UNTIL MID MORNING.
SOME FOG WILL LIKELY DEVELOP AGAIN OVERNIGHT AS LOW CLOUDS
DECREASE AND LINGER LONGER ALONG THE INDIANA BORDER. A WEAK
DISTURBANCE AND WEAKENING FRONT MOVE INTO NORTHERN/CENTRAL IL TUE
AND TO BRING ISOLATED SHOWERS AND THUNDERSTORMS BACK INTO AREA.
SPC HAS MUCH OF CENTRAL/SE IL IN A SLIGHT RISK OF SEVERE STORMS
WED AFTERNOON/EARLY WED EVENING UNTIL SUNSET. THIS DUE TO A STRONG
UPPER LEVEL SHORT WAVE AND COLD FRONT MOVING SE THROUGH IL. VERY
WARM AND HUMID AHEAD OF THIS FRONT THROUGH WED AND THEN TURNING
COOLER AND LESS HUMID THEREAFTER.
LONG TERM...THURSDAY THROUGH SUNDAY
EXTENDED MODELS CONTINUE TO BE PROGRESSIVE WITH YET ANOTHER FAIRLY
STRONG UPPER LEVEL DISTURBANCE TRACKING ESE INTO THE REGION LATE
THIS WEEK AND RETURNING A GOOD CHANCE OF SHOWERS AND ISOLATED
THUNDERSTORMS OVERNIGHT THU NIGHT INTO SAT. MODELS ALSO CONTINUE
TO SHOW A STRONG UPPER LEVEL TROF AND POSSIBLE CUTOFF LOW TAKING
SHAPE OVER THE GREAT LAKES/OHIO VALLEY REGION THIS WEEKEND...BRINGING
BELOW NORMAL TEMPERATURES ALONG WITH DIURNALLY ENHANCED CHANCES OF
SHOWERS AND CLOUDS DURING THE AFTERNOON HOURS.
KH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1030 AM EDT MON SEP 3 2012
.SYNOPSIS...
THE REMNANT LOW OF ISAAC WILL SLOWLY MOVE ACROSS THE UPPER OHIO
VALLEY THROUGH TUESDAY NIGHT, BRINGING THUNDERSTORMS AND HEAVY RAIN
TO THE AREA. A FRONT WILL MOVE THROUGH TUESDAY NIGHT INTO EARLY
WEDNESDAY, BRINGING DRIER WEATHER AS HIGH PRESSURE BUILDS IN FOR
WEDNESDAY. A COLD FRONT WILL CROSS THE AREA ON THURSDAY, RETURNING
THE CHANCE FOR SHOWERS AND THUNDERSTORMS.
&&
.NEAR TERM /THROUGH TONIGHT/...
15Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED IN ORDER TO
ACCOUNT FOR RECENT RADAR TRENDS WITH MORE PERSISTENT RAIN WEST OF
I-77 IN OHIO AND CONVECTION DEVELOPING AND MOVING NORTH OF THE
MASON-DIXON LINE.
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES THE REMNANT 500MB CLOSED
LOW OF TC ISAAC CENTERED IN SOUTHWESTERN OHIO. ABUNDANT MOISTURE IS
PRESENT IN THE 800-300MB LAYER FOR AREAS WEST OF THE I-77 CORRIDOR
IN EASTERN OHIO. THE 12Z KILN SOUNDING AND STRATIFORM PRECIP
INDICATED BY RADAR RETURNS ARE MORE REPRESENTATIVE OF THE TROPICAL
ENVIRONMENT THERE. MEANWHILE, EASTWARD, THE 12Z KPIT SOUNDING IS
REPRESENTATIVE OF A CONVECTIVE ENVIRONMENT WITH 2000 J/KG SBCAPE AND
DRIER MID-LEVELS. IN THIS AIR MASS, ISOLATED SHOWERS AND
THUNDERSTORMS HAVE BEGUN DEVELOP AND MOVE NORTH OF THE MASON-
DIXON LINE.
THIS AFTERNOON...THE REMNANT LOW OF ISAAC WILL SLOWLY CROSS OHIO,
WITH A SOUTHERLY FLOW AHEAD OF THIS FEATURE ADVECTING DEEP LAYER
TROPICAL MOISTURE INTO EASTERN OHIO. THIS WILL ALLOW FOR ANOTHER DAY
OF SHOWERS AND THUNDERSTORMS, WITH PRECIP INCREASING IN COVERAGE
THIS AFTERNOON AND MOSTLY LIKELY FOR LOCATIONS SOUTH AND WEST OF
PITTSBURGH. DESPITE 850MB TEMPS WARMING TO THE 17-18C RANGE WITH
WARM AND MOIST AIR MASS, CLOUD COVERAGE WILL BE A LIMITING FACTOR
WITH HIGHS TODAY. TEMPS ARE CLOSE TO THE GFS LAMP, WITH HIGHS
RANGING IN THE LOW TO MID 80S ACROSS MUCH OF THE AREA.
THE RAP INDICATES SBCAPE INCREASING TO AROUND 2500 IN CONVECTIVE
ENVIRONMENT IN NORTHERN WV AND WESTERN PA. MEANWHILE, EASTERN OHIO
WILL REMAIN INSTABILITY STARVED WITH ONGOING PRECIP. RAINFALL,
REGARDLESS OF ITS CONVECTIVE/TROPICAL NATURE, WILL BE QUITE
EFFICIENT TODAY, WITH THE RAP INDICATING PRECIPITABLE WATER
INCREASING TO 2 INCHES IN MOST AREAS SOUTH OF THE I-80 AND EVEN TO
2.2 INCHES IN PORTIONS OF EASTERN OHIO. WITH VERY WEAK LOW-LEVEL
WINDS TODAY, SHOWERS AND STORMS WILL BE SLOW MOVING. IN ADDITION,
WITH PREVIOUS RAINFALL SATURATING THE GROUND IN NORTH-CENTRAL WV
AND SOUTH OF I-70 IN EASTERN OHIO, 1-HR FFG IS 1 TO 1.5 INCHES.
WITH THIS IN MIND, FLASH FLOODING IS NOT OUT OF THE QUESTION AND
REMAINS IN THE HWO. WILL HAVE TO CONTINUE TO WATCH RADAR AND
MESOSCALE MODEL TRENDS, AS A FLASH FLOOD WATCH MAY BE NEEDED.
GENERALLY ANTICIPATE AROUND A HALF INCH OF PRECIP TODAY, ALTHOUGH
LOCALIZED AREAS COULD SEE TO 2 TO 3 INCHES.
TONIGHT...CONVECTION WILL BE ONGOING EARLY WITH THE MAJORITY OF THE
FORECAST AREA TRANSITIONING TO MORE TROPICAL BY DAWN TUESDAY. THE
CHANCE OF RAIN CANNOT BE RULED OUT OVERNIGHT AS THE REMNANTS OF
ISAAC CONTINUE TO MOVE ACROSS THE AREA. QPF AMOUNTS ARE AROUND A
QUARTER OF AN INCH, ALTHOUGH LOCALIZED HIGHER AMOUNTS WILL BE
POSSIBLE. A WARM AND MUGGY NIGHT CAN BE EXPECTED WITH LOWS A FEW
DEGREES ABOVE MAV/MET GUIDANCE, NEAR 70 ACROSS MOST OF THE AREA.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
SHOWER/STORM CHANCES WILL QUICKLY INCREASE TUESDAY MORNING, AS
THE ENTIRE SYSTEM BEGINS TO PICK UP SPEED AND MOVE TO THE EAST.
THE PUSH WILL COME FROM A SHORTWAVE TROUGH, WHICH WILL CROSS THE
GREAT LAKES TUESDAY MORNING AND MOVE INTO W PA DURING THE
AFTERNOON. THE ENERGY FROM THE NORTHERN TROUGH WILL WORK IN
CONJUNCTION WITH THE ENERGY AND MOISTURE FROM ISAAC`S REMNANTS TO
PROVIDE A WET TUESDAY FOR MUCH OF THE AREA. THE ATMOSPHERE WILL
REMAIN JUICY, SO HEAVY DOWNPOURS ARE A THREAT ON TUESDAY,
ESPECIALLY WITH STORMS THAT MAY DEVELOP.
THE SFC WAVE WILL MOVE THROUGH TUESDAY NIGHT DRAGGING BEHIND THE
SFC COLD FRONT. FRONT WILL STALL ACROSS THE SOUTH AND EAST LATE
TUESDAY NIGHT, WAITING FOR A PUSH FROM THE NEXT UL WAVE. WILL SHOW
A DECREASE IN POPS TUESDAY NIGHT, WHILE LEAVING RAIN CHANCES INTO
WED MORNING ACROSS THE SOUTH AND RIDGES.
WEDNESDAY`S SW TROUGH WILL FINALLY KICK THE ENTIRE SYSTEM OUT OF
THE UPPER OHIO VALLEY, WHICH WILL END THE RISK FOR PRECIPITATION AND
ALSO BRING A SLOW DECREASE IN CLOUD COVER.
SUNSHINE SHOULD MAKE A RETURN BE WED AFTERNOON.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A SECONDARY...AND DECISIVE COLD FRONT IS PROJECTED ACROSS THE AREA BY
THURSDAY. BUILDING HIGH PRESSURE IN THE WAKE OF THE FRONT IS FORECAST
TO BRING DRY WEATHER TO CLOSE THE WEEK. ANOTHER FRONT...CURRENTLY
TIMED FOR AN EARLY SUNDAY APPROACH MAY BRING THE NEXT CHANCE FOR
SHOWERS.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
MVFR STRATUS CAN LINGER NEAR THE MOUNTAINS UNTIL MIDDAY AND AFFECT
KDUJ OR KFKL.
RECENT RADAR DATA SHOWS BAND OF MVFR SHOWERS WILL MOVE SLOWLY
NORTHWARD ACROSS THE UPPER OHIO VALLEY THROUGH AFTERNOON, BUT MAY
NOT REACH KFKL AND KDUJ. AS SURFACE TEMPERATURES HEAT PAST 77,
ISOLATED THUNDERSTORMS WITH HEAVY RAIN CAN DEVELOP.
SURFACE WINDS WILL BECOME MAINLY SOUTHEAST NEAR 10 KTS AFTER 14Z,
THEN DECREASE TO 5 KTS THIS EVENING.
EXPECT MVFR RESTRICTIONS AFTER 08Z DUE TO FOG DEVELOPMENT. FOG COULD
DEVELOP EARLIER IF RAINFALL COVERAGE IS GREATER THAN CURRENTLY
PROJECTED.
.OUTLOOK /TUESDAY THROUGH FRIDAY/...
RESTRICTIONS ARE LIKELY TUESDAY DUE TO MORE NUMEROUS SHOWERS
ASSOCIATED WITH A COLD FRONTAL PASSAGE. RESTRICTIONS WILL STILL
BE POSSIBLE TUESDAY NIGHT INTO THURSDAY DUE TO SCATTERED SHOWERS AND
LATE NIGHT FOG UNTIL A SECOND COLD FRONTAL PASSAGE THURSDAY.
ENSUING DRY CONDITIONS WILL PROMOTE PREVALENT VFR FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
700 AM EDT MON SEP 3 2012
.SYNOPSIS...
THE SYSTEM THAT WAS ONCE TROPICAL CYCLONE ISAAC, WILL TAKE UNTIL
MIDWEEK TO FINALLY CLEAR THE AREA. A COLD FRONT WILL PICK UP THE
REMNANTS AS THE FRONT MOVES THROUGH LATE TUESDAY. THE RISK FOR
SHOWERS OR STORMS WILL CONTINUE INTO EARLY WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
BLEND OF RECENT RADAR DATA AND HRRR MODEL OUTPUT SHOW BANDS OF
SCATTERED SHOWERS WILL BEGIN TO MOVE NORTHWARD THROUGH THE UPPER
OHIO VALLEY TODAY. THESE SHOWER BANDS ARE PART OF THE OUTER
FRINGE OF THE POST-TROPICAL SYSTEM THAT WAS ONCE NAMED ISAAC.
AS DAYTIME HEATING RAISES SURFACE TEMPERATURES INTO THE UPPER 70S,
SCATTERED THUNDERSTORMS WILL DEVELOP, SOME OF WHICH CAN PRODUCE
HEAVY RAINS.
THE I-80 CORRIDOR HAS THE LEAST POTENTIAL OF GETTING ANY BOUTS OF
HEAVY RAIN.
FORECASTED TEMPERATURES TO BE NEAR NORMAL BASED ON RECENT GFS AND
NAM MOS. CONDITIONS WILL REMAIN HUMID WITH SURFACE DEW POINTS 65
TO 70.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
EXPECT A BREAK IN WIDESPREAD ACTIVITY TONIGHT WITH THE LOSS OF
SUNSHINE AND A WEAKENING OF THE UL WAVE. AS RAIN EVAPORATES INTO
THE HUMID NOCTURNALLY-COOLING SURFACE LAYER, AREAS OF FOG CAN
DEVELOP LATE TONIGHT, PARTICULARLY IN THE RIVER VALLEYS.
SHOWER/STORM CHANCES WILL QUICKLY INCREASE TUESDAY MORNING, AS
THE ENTIRE SYSTEM BEGINS TO PICK UP SPEED AND MOVE TO THE EAST.
THE PUSH WILL COME FROM A SHORTWAVE TROUGH, WHICH WILL CROSS THE
GREAT LAKES TUESDAY MORNING AND MOVE INTO W PA DURING THE
AFTERNOON. THE ENERGY FROM THE NORTHERN TROUGH WILL WORK IN
CONJUNCTION WITH THE ENERGY AND MOISTURE FROM ISAAC`S REMNANTS TO
PROVIDE A WET TUESDAY FOR MUCH OF THE AREA. THE ATMOSPHERE WILL
REMAIN JUICY, SO HEAVY DOWNPOURS ARE A THREAT ON TUESDAY,
ESPECIALLY WITH STORMS THAT MAY DEVELOP.
THE SFC WAVE WILL MOVE THROUGH TUESDAY NIGHT DRAGGING BEHIND THE
SFC COLD FRONT. FRONT WILL STALL ACROSS THE SOUTH AND EAST LATE
TUESDAY NIGHT, WAITING FOR A PUSH FROM THE NEXT UL WAVE. WILL SHOW
A DECREASE IN POPS TUESDAY NIGHT, WHILE LEAVING RAIN CHANCES INTO
WED MORNING ACROSS THE SOUTH AND RIDGES.
WEDNESDAY`S SW TROUGH WILL FINALLY KICK THE ENTIRE SYSTEM OUT OF
THE UPPER OHIO VALLEY, WHICH WILL END THE RISK FOR PRECIPITATION AND
ALSO BRING A SLOW DECREASE IN CLOUD COVER.
SUNSHINE SHOULD MAKE A RETURN BE WED AFTERNOON.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A SECONDARY...AND DECISIVE COLD FRONT IS PROJECTED ACROSS THE AREA BY
THURSDAY. BUILDING HIGH PRESSURE IN THE WAKE OF THE FRONT IS FORECAST
TO BRING DRY WEATHER TO CLOSE THE WEEK. ANOTHER FRONT...CURRENTLY
TIMED FOR AN EARLY SUNDAY APPROACH MAY BRING THE NEXT CHANCE FOR
SHOWERS.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
EXPECT ANY REMAINING MVFR CONDITIONS FROM FOG TO END BY 14Z. MVFR
STRATUS CAN LINGER NEAR THE MOUNTAINS UNTIL MIDDAY AND AFFECT
KDUJ, KLBE, AND KMGW.
RECENT RADAR DATA SHOWS BAND OF MVFR SHOWERS WILL MOVE SLOWLY
NORTHWARD ACROSS THE UPPER OHIO VALLEY THROUGH AFTERNOON, BUT MAY
NOT REACH KFKL AND KDUJ. AS SURFACE TEMPERATURES HEAT PAST 77,
ISOLATED THUNDERSTORMS WITH HEAVY RAIN CAN DEVELOP.
SURFACE WINDS WILL BECOME MAINLY SOUTHEAST NEAR 10 KTS AFTER 14Z,
THEN DECREASE TO 5 KTS THIS EVENING.
EXPECT MVFR RESTRICTIONS AFTER 08Z DUE TO FOG DEVELOPMENT. FOG COULD
DEVELOP EARLIER IF RAINFALL COVERAGE IS GREATER THAN CURRENTLY
PROJECTED.
.OUTLOOK /TUESDAY THROUGH FRIDAY/...
RESTRICTIONS ARE LIKELY TUESDAY DUE TO MORE NUMEROUS SHOWERS
ASSOCIATED WITH A COLD FRONTAL PASSAGE. RESTRICTIONS WILL STILL
BE POSSIBLE TUESDAY NIGHT INTO THURSDAY DUE TO SCATTERED SHOWERS AND
LATE NIGHT FOG UNTIL A SECOND COLD FRONTAL PASSAGE THURSDAY.
ENSUING DRY CONDITIONS WILL PROMOTE PREVALENT VFR FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
731 AM EDT MON SEP 3 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 429 AM EDT MON SEP 3 2012
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WSW FLOW ALF OVER
THE UPR GRT LKS BTWN UPR RDG EXTENDING FM THE PLAINS INTO LWR MI AND
DEEP...OCCLUDED LO OVER NRN SASKATCHEWAN THAT IS DRIFTING ONLY
SLOWLY EWD. THE REMNANTS OF HURRICANE ISAAC CONTINUE TO DRIFT EWD
THRU THE OH VALLEY S OF THE UPR RDG AXIS. WARM CONVEYOR BELT MSTR
RIBBON...IN ADVANCE OF COLD FNT MOVING THRU MN THAT IS ATTENDANT TO
SASKATCHEWAN OCCLUSION...HAS PUSHED INTO ERN MN/WRN UPR MI.
HOWEVER...CIRCULATION ARND ISAAC HAS LIMITED MSTR INFLOW INTO THIS
SYSTEM AS EVIDENCED BY VERY DRY AIRMASS SHOWN ON THE 00Z MPX RAOB
AND H85 DEWPT DEPRESSIONS NEAR 20C STRETCHING FM THAT SITE SWWD INTO
THE CENTRAL PLAINS. SINCE THIS DRY AIR IS FEEDING NEWD TOWARD NE
MN/UPR MI IN THE SSW SFC-H85 FLOW AHEAD OF COLD FNT...AT 06Z THERE
WAS NO PCPN FALLING S OF THE CNDN BORDER FM THIS CLD DESPITE STEEP
MID LVL LAPSE RATES AND MUCAPE 500-1000 J/KG AS SHOWN BY SPC
MESOANALYSIS. ISOLD -SHRA/A FEW LTG STRIKES WERE EVIDENT IN ONTARIO
WHERE MSTR IS DEEPER PER 00Z YPL RAOB CLOSER TO SHARPER DEEP LYR
QVECTOR CNVGC ASSOCIATED WITH OCCLUSION TO THE W. HOWEVER...APRCH OF
70KT H3 JET MAX IN THE NRN PLAINS/SOME UPR DVGC HAS CAUSED MORE
SHRA/TS TO DVLP OVER WRN LK SUP CLOSER TO FCST ISSUANCE. BEHIND THE
COLD FNT IN THE NRN PLAINS...00Z ABERDEEN SDAKOTA AND BISMARCK RAOBS
SHOW A VERY DRY AIRMASS. LATEST WV IMAGERY SHOWS THIS DRIER AIR ALF
SPREADING EWD.
MAIN FCST CONCERNS IN THE SHORT TERM ARE SHRA/TS CHCS TODAY AS COLD
FNT/MSTR RIBBON PRESS TO THE E.
TODAY...COLD FNT IN MN IS PROGGED TO DRIFT INTO UPR MI AND DISSIPATE
AS THIS BNDRY OUTRUNS THE CLOSED LO IN SASKATCHEWAN THAT IS PROGGED
TO DRIFT ONLY SLOWLY INTO MANITOBA. PCPN CHCS WL BE HINDERED BY DRY
ADVECTION NOTED ABOVE AND EXIT OF DEEP LYR QVECTOR CNVGC TO THE N.
HOWEVER...BULK OF MODELS SHOWED THE INCRSG H4-2 UPR DVGC EARLY THIS
MRNG IN ADVANCE OF JET MAX MOVING ENEWD THRU THE NRN PLAINS...SO
WENT WITH SCT -SHRA/TSRA TO START OFF FCST PERIOD OVER THE W WITH
THE SOMEWHAT HIER POPS FARTHER TO THE N CLOSER TO DEEPER MSTR/
LINGERING DEEP LYR QVECTOR CNVGC. THIS UPR DVGC IS PROGGED TO EXIT
TO THE NE BY MID MRNG...SO EXPECT POPS TO DIMINISH FOR A TIME.
QUESTION THEN BECOMES WHETHER DAYTIME HEATING CAN INVIGORATE DIURNAL
CONVECTION IN ABSENCE OF APPRECIABLE DYNAMIC SUPPORT AND AGAINST
ONSLAUGHT OF INCOMING DRY AIR THAT IS PROGGED TO DROP KINX BLO 10
OVER THE W HALF BY 18Z FOLLOWING THE DISSIPATING COLD FROPA PER
FAVORED GFS THAT BEST MATCHES WV IMAGERY TRENDS OF VIGOROUS DRYING
ALF MOVING E FM THE NRN PLAINS. BEST SHOT FOR THIS CONVECTION
APPEARS TO BE OVER THE E AND SCNTRL...WHERE KINX IS PROGGED TO
REMAIN NEAR 30 THRU 18Z AND WHERE DVLPG LK BREEZES MIGHT ENHANCE
LLVL CNVGC. BUT EVEN IN THIS AREA...KINX IS FCST TO FALL BLO 20 BY
00Z EXCEPT FOR AREAS NEAR LK MI. AS FOR SVR THREAT...MODELS DEPICT
DEEP LYR SHEAR AS HI AS 30-35 KTS OVER THE SCNTRL AT 18Z. MODIFIED
GFS FCST SDNG FOR ESC AT 18Z FOR SFC T/TD 83/66 YIELDS SBCAPE NEAR
1400 J/KG DESPITE LESS IMPRESSIVE MID LVL LAPSE RATES FCST IN THAT
AREA. WITH VIGOROUS DRYING ALF...SFC-10K DELTA THETA-E IS PROGGED TO
INCRS TO A SGNFT 25-30C BY LATE IN THE DAY...INCRSG THE DCAPE IN THE
PRESENCE OF UNIDIRECTIONAL WLY FLOW ALF/THREAT FOR DAMAGING WINDS.
DESPITE MID LVL DRYING...FCST HI WBZ NEAR 13K FT WOULD PROBABLY
MINIMIZE THE POTENTIAL FOR LARGE HAIL. BUT MAIN CONCERN IS HOW
VIGOROUS MID LVL DRYING WL IMPACT SHRA/TS CHCS. IN FACT...THE
GREATER SHEAR MIGHT ACT TO ENTRAIN SO MUCH DRIER AIR INTO THE STORM
TOWERS AND LIMIT THE INTENSITY OF THE CONVECTION. WL CONTINUE TO
MENTION THE THREAT OF SOME STRONGER STORMS IN THE HWO. AS FOR HI
TEMPS...MIXING TO H85 ON GFS FCST SDNGS YIELDS HI TEMPS REACHING THE
MID/UPR 80S AWAY FM LK MODERATION...IN GOOD AGREEMENT WITH MAX TEMPS
OBSVD UPSTREAM ON SUN.
TNGT...WITH VIGOROUS UPR DRYING PER THE GFS THAT CAUSES H85-5 MEAN
RH TO FALL AS LO AS 20 PCT BY 06Z...ANY LINGERING SHRA/TS OVER THE
SE CWA IN THE EARLY EVNG WL END WITH LOSS OF DAYTIME HEATING IN THE
ABSENCE OF ANY DYNAMIC SUPPORT. CONSIDERING DRYNESS OF INCOMING
AIRMASS AND LGT WINDS UNDER BUBBLE HI PRES BLDG INTO THE AREA...
TENDED TOWARD THE LOWER GFS GUIDANCE FOR MIN TEMPS. VIGOROUS DRYING
ALF/LGT WINDS FAVOR FOG DEVELOPMENT...SO WENT WITH AREAS OF FOG OVER
MUCH OF THE INTERIOR.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 429 AM EDT MON SEP 3 2012
THE PERIOD STARTS 12Z TUE WITH A CLOSED UPPER LOW OVER NRN
MANITOBA...AND A SFC TROUGH/WEAK COLD FRONT W OF THE CWA. SHORTWAVE
ENERGY IS THEN COMBINED INTO THE SRN SIDE OF THE UPPER LOW THROUGH
WED...CAUSING THE SYSTEM TO MOVE FARTHER W TO FAR NW ONTARIO BY 00Z
THU. EXACTLY WHEN AND WHERE THE SHORTWAVE ENERGY MOVES WILL GREATLY
IMPACT THE FORECAST FOR TUE AND TUE NIGHT...SO CONFIDENCE IS LOWER
FOR THIS TIME PERIOD. WE COULD STAY DRY ACROSS MOST OF THE CWA ON
TUE...AS THE 12Z/02 ECMWF SHOWS DUE TO THE SHORTWAVE STAYING FATHER
TO THE N THAN IN OTHER MODELS. ALSO...MODEL FORECAST SOUNDING SHOW
DIFFERENCES BETWEEN LOW LEVEL MOISTURE WHICH WILL RESULT IN
INCREASED TO DECREASED CIN. WILL NOT CHANGE THE PREVIOUS POP
FORECAST WITH SLIGHT CHANCE TO LOW CHANCE POPS MAINLY IN THE
AFTERNOON. IF SHOWERS AND THUNDERSTORMS DO DEVELOP...THERE MAY BE
SOME STRONG TUE AFTERNOON AS CAPE INCREASES TO AOA 1500 J/KG BUT
0-6 KM SHEAR REMAINS BELOW 25 KTS.
A STRONGER COLD FRONT/SFC TROUGH SHOULD MOVE THROUGH ON WED...BUT
TIMING AND INTENSITY REMAINS IN QUESTION AS MODELS DO NOT HANDLE THE
SITUATION WELL. THIS IS AGAIN RELATED TO THE PATH THE SHORTWAVE
TAKES. THE DIFFERENCES BETWEEN TIMING PLAY OUT THE MOST WITH
THUNDERSTORM INTENSITY ON WED...WITH THE SLOWER GUIDANCE BRING THE
FRONT THROUGH AROUND PEAK HEATING WHICH WOULD RESULT IN MORE
INSTABILITY. THE FASTER MODELS MOVE THINGS THROUGH EARLIER AND
THEREFORE...INSTABILITY RESULTING FROM DAYTIME HEATING IS MAXIMIZED
AOA 1500 J/KG. 0-6KM SHEAR SHOULD BE ON THE ORDER OF 40-50
KTS...WITH 0-1KM SHEAR OF AROUND 15 KTS. FLOW WILL BE MOSTLY
UNIDIRECTIONAL...SO THE SHEAR IS MOSTLY SPEED SHEAR. MORE ALONG THE
LINES OF WORST CASE SCENARIO REGARDING TIMING/INSTABILITY...SOME
STORMS COULD BE SEVERE IN THE AFTERNOON WITH WIND GUSTS BEING THE
PRIMARY HAZARD /DUE PARTY TO DRY MID LEVELS/. THERE WOULD BE A LARGE
HAIL THREAT...BUT THAT IS MORE CONDITIONAL. REGARDLESS OF TIMING OF
THE FRONT...PRECIP DOES LOOK MORE CERTAIN THAN ANY OTHER DAY IN THE
EXTENDED...BUT THAT SHORTWAVE WILL MAKE THINGS TRICKY. INCREASED
POPS TO LIKELY...ESPECIALLY CENTRAL AND E...AND HIGH CHANCE POPS
OVER THE FAR W.
THE UPPER LOW WILL CONTINUE TO MOVE EVERY SO SLOWLY ESE...AND WILL
BE CLOSEST TO THE CWA THU NIGHT. EXPECT 850MB TEMPS AROUND 4-6C THU
INTO FRI..WHICH MAY LEAD TO SOME LAKE EFFECT RAIN DOWNWIND OF N/NW
WINDS. MODEL AGREEMENT AND CONTINUITY DEGRADE SIGNIFICANTLY FRIDAY
THROUGH SUNDAY...SO CONFIDENCE IS SIGNIFICANTLY LOWER FOR NEXT
WEEKEND. IT DOES APPEAR...HOWEVER...THAT A RETURN TO OR EVEN BELOW
NEAR NORMAL TEMPERATURES IS IN STORE FOR THU THROUGH SUN. USED
CONSENSUS OF MODEL GUIDANCE GIVEN UNCERTAINTY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 730 AM EDT MON SEP 3 2012
EXPECT TS THAT IMPACTED CMX TO BE OVER BY 12Z..WITH DRY AIR
FOLLOWING IN THE WAKE OF A WEAK COLD FRONTAL PASSAGE ENDING THE PCPN
THREAT THERE AND AT IWD BY MID MRNG AS THE BETTER DYNAMIC SUPPORT
LIFTS TO THE N. SOME SHRA/TS MAY IMPACT SAW LATE THIS MRNG INTO
EARLY AFTN AS WELL WITH DAYTIME HEATING COINCIDING WITH THE ARRIVAL
OF THE FNT. BUT THE ARRIVAL OF DRIER AIR ALF SHOULD END THE SHRA
THREAT THERE AS WELL. ALTHOUGH CIGS/VSBY MAY BE LOWER UNDER ANY
HEAVIER SHRA...VFR CONDITIONS SHOULD BE THE RULE AT ALL SITES INTO
THIS EVNG. WITH LGT NEAR SFC WINDS UNDER THE UPR LVL DRYING...FOG IS
LIKELY TO FORM AT SAW/IWD OVERNGT...WITH IFR CONDITIONS POSSIBLE.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 429 AM EDT MON SEP 3 2012
EXPECT S WINDS UP TO 20 KTS IN ADVANCE OF AN APPROACHING COLD FRONT
TO DIMINISH TODAY AS THE FRONT TENDS TO WEAKEN. LIGHT WINDS WILL
THEN PREVAIL THRU TONIGHT AS A WEAK HI PRES SYSTEM MOVES INTO THE
UPPER GREAT LAKES. A SERIES OF LOW PRESSURE SYSTEMS AND COLD FRONTS
WILL MOVE NEAR LAKE SUPERIOR TUESDAY THROUGH SUNDAY...LEADING TO
PERIODS OF INCREASED WINDS. HOWEVER...AT THIS TIME WINDS ARE EXPECTED
TO REMAIN BELOW 25KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...KC
MARINE...KC/TITUS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
622 AM CDT MON SEP 3 2012
.AVIATION...12Z TAF. VFR CONDITIONS FORECAST FOR THIS TAF
PERIOD...THOUGH THE TERMINAL COULD SEE A FEW SHOWERS PASS THROUGH
THIS MORNING. OUTSIDE OF THIS MORNING...THERE ARE OTHER CHANCES
FOR PRECIPITATION IN THE AREA...BUT NOT CONFIDENT ENOUGH IN
ANYTHING AFFECTING THE TERMINAL TO PUT IN ANY MENTION. VARIABLE
WINDS LOOK TO CONTINUE THIS MORNING...BEFORE TURNING MORE TO THE
SOUTHEAST THIS AFTERNOON. SPEEDS EXPECTED TO BE ON THE LIGHT SIDE.
&&
.PREV DISCUSSION... /ISSUED 345 AM CDT MON SEP 3 2012/
SHORT TERM...THROUGH 12Z THURSDAY. OVERNIGHT UPPER AIR ANALYSIS
INDICATES A LONG WAVE RIDGE OVER THE EASTERN CONUS AND A TROUGH
OVER THE WEST. SOUTHWESTERLY TO ZONAL MID AND UPPER LEVEL FLOW
EXISTS OVER THE MUCH OF THE CENTRAL CONUS AS A RESULT. MID AND
UPPER LEVEL JET ENERGY EXTENDS FROM SOUTHERN
CALIFORNIA...NORTHEAST INTO THE NORTHERN PLAINS AND PORTIONS OF
THE CENTRAL PLAINS...AS WELL AS SOUTHERN CANADA...AND THEN
SOUTHEAST INTO THE NORTHEASTERN CONUS. A ~90KT UPPER LEVEL JET
STREAK IS ALSO EVIDENT OVER THE CENTRAL AND NORTHERN ROCKY
MOUNTAIN RANGE. WATER VAPOR IMAGERY INDICATES INCREASED LEVELS OF
MID LEVEL MOISTURE EXTENDING NORTHWARD FROM MEXICO INTO THE
SOUTHWESTERN CONUS...AND THEN NORTHEAST INTO THE CENTRAL PLAINS.
AT THE SURFACE A WEAK COLD FRONT EXTENDS FROM NORTHEAST NEBRASKA
TO SOUTHWEST KANSAS. THE LOW LEVEL WIND FIELD REMAINS FROM THE
SOUTHEAST ACROSS SOUTHEASTERN PORTIONS OF THE OUR CWA...WITH MORE
OF A NORTHERLY LOW LEVEL WIND FIELD NOTED FARTHER NORTHWEST ACROSS
THE AREA BEHIND THE FRONT.
GUIDANCE FROM THE NAM AND OPERATIONAL GFS CONTINUE TO SUGGEST THE
UPPER LEVEL JET STREAK...CURRENTLY OVER THE CENTRAL AND NORTHERN
ROCKY MOUNTAIN RANGE...WILL CONTINUE MOVING EAST/NORTHEAST
TODAY...WITH THE RIGHT-REAR QUADRANT OF THIS JET STREAK SETTING UP
SHOP OVER NORTHERN PORTIONS OF OUR CWA. QPF FIELDS FROM THE
NAM...OPERATIONAL GFS AND SREF-MEAN...AS WELL AS SIMULATED
REFLECTIVITY FROM THE 4KM WRF-NMM AND HRRR ALL SUGGEST ENOUGH OF A
DIRECT THERMAL CIRCULATION AND RESULTANT FRONTOGENESIS WILL BE
PRESENT FOR ISOLATED TO SCATTERED PRECIPITATION PRODUCTION OVER
NORTHERN PORTIONS OF OUR AREA THROUGH 18Z. THESE MODEL SOLUTIONS
HAVE BEEN FAIRLY CONSISTENCE SETS OF GUIDANCE THROUGH THE PAST
THREE DAYS AND AS A RESULT WILL GO AHEAD AND MAINTAIN 20%-30% POPS
MAINLY ACROSS NORTHERN PORTIONS OF OUR CWA THROUGH 18Z. GUIDANCE
SUGGESTS THE UPPER LEVEL JET STREAK WILL WEAKEN AND PUSH
EAST/NORTHEAST OF OUR AREA BY THIS AFTERNOON...WHICH WOULD
OTHERWISE BRING AND END TO THE PRECIPITATION CHANCES ACROSS OUR
AREA. THAT BEING SAID...THERE REMAIN INDICATIONS FROM THE NAM AND
OPERATIONAL GFS OF MULTIPLE SMALL SCALE MID LEVEL PERTURBATIONS
PUSHING NEAR OR OVER THE AREA THROUGH THIS AFTERNOON AND EVENING.
GIVEN THE WEAK FORCING AND DIFFICULTY IN ASSIGNING PRECIPITATION
CHANCES TO AN AREA GIVEN THE SUBTLE NATURE OF THESE SMALL SCALE
PERTURBATIONS...QPF FIELDS FROM THE NAM...OPERATIONAL
GFS...EC...AND SREF-MEAN ARE ALL OVER THE PLACE AND OFFER LITTLE
IN THE WAY OF HELP IN TRYING TO DETERMINE WHERE AFTERNOON
CONVECTION WILL MOST LIKELY BE REALIZED. YESTERDAY AT THIS TIME IT
WAS BELIEVED THE WEAK LOW LEVEL BAROCLINIC ZONE...CURRENTLY OVER
OUR AREA...WOULD SLOWLY DRIFT TO THE SOUTHEAST AND WOULD PROVIDE
ADDITIONAL LOW LEVEL CONVERGENCE FOR SURFACE-BASED CONVECTION
DURING THE AFTERNOON AND EARLY EVENING HOURS. HOWEVER NOW IT
APPEARS THIS BAROCLINIC ZONE WILL QUICKLY EXIT OUR AREA TO THE
SOUTHEAST BY EARLY AFTERNOON AND WILL OFFER LITTLE IN THE WAY OF
ADDITIONAL FORCING FOR CONVECTIVE INITIATION. LONG STORY
SHORT...CONFIDENCE IS VERY LOW REGARDING MEASURABLE PRECIPITATION
BEING REALIZED AT ANY ONE LOCATION ACROSS THE CWA THIS AFTERNOON
AND EVENING. BUT BECAUSE MOST ALL MODELS SUGGEST AT LEAST SOME
ISOLATED CONVECTIVE ACTIVITY WILL BE OBSERVED...AGAIN NO TELLING
WHERE FOR SURE...WILL GO AHEAD AND CARRY 20% POPS ACROSS THE
ENTIRE CWA 18Z MONDAY THROUGH 06Z TUESDAY. AS FOR SEVERE WEATHER
CHANCES THIS AFTERNOON AND EVENING...WILL CONTINUE TO DISREGARD
THE OPERATIONAL GFS WHICH SUGGESTS SURFACE DEW POINTS IN THE MID
70S WILL BE REALIZED ACROSS PORTIONS OF THE CWA THIS AFTERNOON.
BOIVERIFY SUGGESTS BCCONSALL CONTINUES TO BE A GOOD PERFORMER WITH
RESPECT TO SURFACE DEW POINTS ACROSS OUR AREA AND THIS SET OF
GUIDANCE SUGGESTS AFTERNOON DEW POINTS WILL REMAIN GENERALLY IN
THE LOW TO MID 60S ACROSS OUR AREA...WITH PERHAPS A FEW UPPER 60
READINGS ACROSS OUR EAST...WHICH IS ALSO WHAT THE NAM CONTINUES TO
SUGGEST. FOLLOWING CLOSER TO THE NAM WOULD ALSO SUGGEST 0-1KM
MLCAPE VALUES OF ~1000J/KG WILL BE IN PLACE ACROSS THE AREA THIS
AFTERNOON AND EVENING. NOT THAT THESE POTENTIAL INSTABILITY VALUES
ARE SOMETHING TO GET OVERLY EXCITED ABOUT BUT WITH THE UPPER LEVEL
JET AXIS OVER THE AREA...DEEP LAYER BULK SHEAR VALUES ON THE ORDER
OF 40KTS WILL ALSO LIKELY BE PRESENT. ALTHOUGH INITIAL UPDRAFT
STRENGTH WILL LIKELY BE MARGINAL AT BEST FOR LARGE HAIL
PRODUCTION...THE ROTATIONAL POTENTIAL OF SAID UPDRAFT MAY ENHANCE
IT ENOUGH FOR A BETTER HAIL THREAT. GIVEN ALL THIS...IT STILL
SEEMS POSSIBLE THAT UPDRAFT STRENGTH COULD BE STRONG ENOUGH TO
SUPPORT LARGE HAIL AND AS A RESULT...WILL GO AHEAD AND CONTINUE TO
OUTLOOK THE AREA FOR POSSIBLE SEVERE WEATHER THIS AFTERNOON AND
EVENING. LOSS OF DIABATIC HEATING POST-SUNSET SHOULD KILL ANY
CONVECTION BEYOND 03Z THIS EVENING...WITH AN OVERALL LACK IN
KINEMATIC FORCING LIKELY PROVIDING DRY CONDITIONS TO THE AREA 03Z-
18Z TUESDAY.
GUIDANCE FROM THE NAM...OPERATIONAL GFS...AND EC ALL SUGGEST A
MORE SIGNIFICANT MID LEVEL SHORT WAVE WILL PUSH INTO SOUTH CENTRAL
CANADA AND PORTIONS OF THE NORTH CENTRAL CONUS TUESDAY INTO
TUESDAY NIGHT. A RESULTANT AREA OF SURFACE LOW PRESSURE IS
EXPECTED TO PUSH ACROSS THE NORTHERN PLAINS AND UPPER MISSISSIPPI
VALLEY DURING THE SAME TIME PERIOD...WITH AN ASSOCIATED SURFACE
COLD FRONT EXPECTED TO SWEEP ACROSS NEBRASKA. AT THIS TIME THE LOW
LEVEL BAROCLINIC ZONE IS EXPECTED TO NEAR NORTH/NORTHWESTERN
PORTIONS OF OUR CWA BY 00Z WEDNESDAY...LIKELY CLEARING THE ENTIRE
CWA BY 12Z WEDNESDAY. SURFACE-BASED CONVECTION WILL BE POSSIBLE IN
THE VICINITY OF THIS LOW LEVEL BAROCLINIC ZONE ACROSS OUR
NORTH/NORTHWEST BY LATE AFTERNOON TUESDAY...WITH ADDITIONAL
CONVECTIVE ACTIVITY PERHAPS SPREADING SOUTHEAST ACROSS THE CWA
HEADING INTO THE EVENING AND OVERNIGHT HOURS TUESDAY. GIVEN ALL
THIS...WILL GO AHEAD WITH 20%-30% POPS ACROSS THE CWA 21Z TUESDAY
THROUGH 12Z WEDNESDAY. POOLING OF LOW LEVEL MOISTURE AHEAD OF THE
LOW LEVEL BAROCLINIC ZONE...AS SUGGESTED BY THE NAM...MAY ACTUALLY
HELP TO INCREASE POTENTIAL INSTABILITY ACROSS OUR AREA WHEN
COMPARED TO MONDAY...WITH THE NAM SUGGESTING 0-1KM MLCAPE VALUES
ON THE ORDER OF 1500J/KG POSSIBLE TUESDAY AFTERNOON INTO THE
EVENING HOURS. IN ADDITION...DEEP LAYER BULK SHEAR VALUES OF
AROUND 35KTS WILL ALSO BE IN EXISTENCE. GIVEN ALL THIS...WILL
CONTINUE THE SEVERE WEATHER MENTION IN THE HWO FOR TUESDAY.
A COOLER AND DRIER AIRMASS WILL SETTLE IN ACROSS THE AREA BEHIND
THE LOW LEVEL BAROCLINIC ZONE WEDNESDAY AND WEDNESDAY NIGHT...AND
AN OVERALL LACK IN KINEMATIC FORCING SHOULD PRESENT DRY CONDITIONS
TO OUR AREA 12Z WEDNESDAY THROUGH 12Z THURSDAY.
AN EASTERLY COMPONENT TO THE LOW LEVEL WIND FIELD AND A SLIGHTLY
COOLER AIRMASS WILL PRESENT COOLER CONDITIONS TO THE AREA TODAY
WHEN COMPARED TO SUNDAY...WITH AFTERNOON HIGHS IN THE LOW TO MID
90S EXPECTED THROUGH MOST LOCATIONS. WARMER WEATHER AHEAD OF THE
APPROACHING LOW LEVEL BAROCLINIC ZONE WILL LIKELY PRESENT
AFTERNOON HIGHS IN THE MID TO UPPER 90S ON TUESDAY. THE COOLER
AIRMASS ON WEDNESDAY WILL LIKELY KEEP AFTERNOON HIGHS IN THE 80S
TO FINISH OUT THE SHORT TERM FORECAST PERIOD. OVERNIGHT LOWS IN
THE 60S WILL REMAIN THE NORM MONDAY NIGHT AND TUESDAY NIGHT...WITH
THE COOLER AIRMASS LIKELY PROMOTING TEMPERATURES IN THE 50S
WEDNESDAY NIGHT INTO THURSDAY MORNING.
LONG TERM...THURSDAY THROUGH SUNDAY. PRIMARY FORECAST CONCERNS
LIE WITH END OF THE WEEK PRECIPITATION CHANCES...AND TEMPERATURES.
THE START OF THE LONG TERM PERIOD SHOWS MODELS NOT IN TOO BAD OF
AGREEMENT WITH THE PATTERN ACROSS THE CONUS...WHICH REMAINS
ZONAL...SET UP BETWEEN BROAD HIGH PRESSURE EXTENDING ACROSS THE
DESERT SW AND SRN PLAINS...WHILE A LARGE LOW PRESSURE SYSTEM SPINS
OVER CENTRAL CANADA. THROUGH THE END OF THE WORK
WEEK...PRECIPITATION CHANCES CONTINUE ACROSS THE CWA...DRIVEN BY A
COUPLE OF DISTURBANCES ASSOCIATED WITH THAT CANADIAN LOW PRESSURE
SYSTEM. THE FIRST ONE LOOKS TO AFFECT THE AREA MAINLY ON
THURSDAY/THURSDAY NIGHT...ALSO PUSHING A SURFACE BOUNDARY INTO
ROUGHLY THE NORTHERN HALF OF THE CWA DURING THE AFTERNOON HOURS.
THE SECOND DISTURBANCE...DIVING BASICALLY STRAIGHT SOUTH OUT OF
CANADA...AFFECTS THE AREA MAINLY FRIDAY/FRIDAY EVENING. KEPT POPS
CWA-WIDE THURS/THURS NIGHT/FRI...WITH ONLY A FEW LINGERING POPS
INTO FRIDAY NIGHT ACROSS NC KS...AND IF CURRENT MODEL TRENDS
CONTINUES...THOSE FRIDAY EVENING/NIGHT POPS COULD BE REMOVED. AS
MENTIONED...THURSDAY SEE THE INITIAL FRONT MOVE INTO THE CWA...BUT
THAT SECOND DISTURBANCE WILL USHER IN A REINFORCING COLD
FRONT...ACCOMPANIED BY THE COOLER/DRIER AIR FOR FRIDAY. FORECAST
HIGHS FOR THURSDAY SIT IN THE 80S...WHILE FRIDAY IS IN THE MID
70S/LOWER 80S. WILL KEEP THE MENTION OF SOME STRONG/SEVERE
THUNDERSTORMS GOING FOR THIS PERIOD WITH MODELS CONTINUING TO SHOW
THE POTENTIAL FOR DECENT INSTABILITY/SHEAR IN THE AREA.
PLEASANT CONDITIONS ON TAP FOR THE UPCOMING WEEKEND...WITH MODELS
DEPICT DRIER NORTHWESTERLY FLOW SETTING UP IN THE UPPER LEVELS
ACROSS THE CENTRAL PLAINS...SITTING BETWEEN THE TROUGH/LOW OVER
THE GREAT LAKES AND MIDWEST...WHILE RIDGING BUILDS INTO THE
ROCKIES. HIGH PRESSURE LOOKS TO BE THE PRIMARY PLAYER AT THE
SURFACE...BUILDING IN FROM THE NORTHWEST BEHIND THE END OF THE
WORK WEEK FRONTAL PASSAGE. EXPECTING TO SEE PLENTY OF
SUNSHINE...WITH FAIRLY LIGHT WINDS /ESP ON SAT/. THE AREA OF SFC
HIGH PRESSURE LOOKS TO BE CENTERED RIGHT OVER THE CWA ON
SATURDAY...BEFORE SLIDING OFF SLIGHTLY TO THE EAST ON SUNDAY...AND
EXPECTING SATURDAY TO BE A TOUCH COOLER THAN SUNDAY. CURRENT
FORECAST HIGHS ON SATURDAY SIT IN THE MID 70S...WITH SUNDAY
CREEPING UP INTO THE UPPER 70S TO LOWER 80S...BOTH DAYS FEELING
PRETTY NICE WITH DEWPOINTS LOOKING TO BE IN THE 40S FOR MOST
LOCATIONS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
629 AM EDT MON SEP 3 2012
.SYNOPSIS...
THE REMNANTS OF ISAAC WILL EFFECT THE REGION THROUGH TUESDAY
NIGHT. BRIEF DRY AIR CAN BE EXPECTED FOR WEDNESDAY. A WEAK COLD
FRONT ARRIVES THURSDAY...FOLLOWED BY LOW PRESSURE FOR NEXT WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
630AM UPDATE...
TWEAKED POPS TO ACCOUNT FOR ONGOING PCPN BAND ACROSS SE OH. STILL
LOOKING FOR AFTN DEVELOPMENT AFTER SOME OF THE CLDS BURN OFF SOME.
LATEST HRRR SHOWS THIS DEVELOPMENT ARND 18Z ACROSS W AND S...AND
ROTATING THRU LATER IN AFTN.
PREVIOUS DISCUSSION BELOW...
CIRCULATION WITH ISAAC TO SLOWLY CONT TO MOVE SE THRU C KY AND TN
IN THE NEAR TERM. AS IT DOES SO IT WILL ALSO CONT TO
WEAKEN...OPENING UP INTO A BROAD TROF TONIGHT. STILL ROLLING WITH
CONSENSUS PLACEMENT OF H5 VORT/MID LVL DEFORMATION AXIS FOR
PLACEMENT AND TIMING OF POPS FROM BANDS SPIRALING INTO AREA. ONE
SUCH BAND CONT TO WEAKEN ACROSS EASTERN KY...STRUGGLING TO MAKE
MUCH E PROGRESS. THINK SOME ADDITIONAL DEVELOPMENT MAY FORM JUST
AHEAD OF WHAT IS LEFT OF THIS BAND WITH LINGERING INSTABILITY
NOTED ACROSS THE CWA. WILL FINESSE DETERMINISTIC POPS FOR THIS
EARLY MORNING WITH THIS THINKING IN MIND...HOLDING CAT AND LKLY
POPS ACROSS W AND S ZONES. TRACK THIS N THRU CWA AFTER SUNRISE
WITH YET ANOTHER BAND POISED TO ROTATE THRU LATER IN THE DAY. AS
SUCH DONT EXPECT WASHOUT OF A DAY...WITH SOME LULLS IN BETWEEN.
QPF TDY DEPENDENT ON HOW CONVECTIVE THE ACTION IS. WITH PWATS
STILL RUNNING ABV 2 INCHES...POTENTIAL EXISTS FOR SOME LCL 1 TO 2
INCHES OF RAIN...WITH A GENERAL HALF INCH TO INCH EXPECTED MOST
PLACES. FFG CONT TO RUN ON HIGH SIDE ACROSS NE KY DOWN THRU SW WV
AND SW VA WITH LWR VALUES ACROSS SE OH INTO C AND N WV. IT IS THIS
AREA THAT IS OF CONCERN...AS 1.5 TO 2.5 INCHES OF RAIN FELL THERE
YESTERDAY. GIVEN THAT...AND ENOUGH CONFIDENCE ON PLACEMENT OF VORT
THIS AFTN AND EVE ACROSS ESPECIALLY SE OH...WILL HOIST A FLASH
FLOOD WATCH THRU THIS EVENING FOR NORTHERN TIER OF CO FROM PERRY
TO HARRISON.
EXPECT ACTION TO WANE AFTER SUNSET WITH LOSS OF HEATING. HOWEVER
WITH A COUPLE MORE SPOKES PROGGED ON MDLS TO MOVE THRU OVERNIGHT
TONIGHT...KEPT SOME CHC POPS IN. THINK SOME LOW STRATUS WILL BE IN
THE CARDS TONIGHT AS WELL...LESS SO PERHAPS OVER C WV DUE TO WEAK DOWNSLOPING.
GUIDANCE TIGHTLY CLUSTERED FOR TEMPS...SO ROLLED WITH A BLEND.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
MOISTURE FROM ISAAC REMAINS OVER THE AREA ON TUESDAY. MODEL
SOUNDINGS CONTINUE TO LOOK VERY UNSTABLE. THEREFORE WILL GO WITH
LIKELY POPS DURING THE AFTERNOON HOURS. THE MOISTURE FINALLY PUSHES
EAST OF THE AREA TUESDAY NIGHT AND EARLY WEDNESDAY. THEREFORE...WILL
REMOVE POPS ON WEDNESDAY AFTERNOON. A WEAK MOISTURE STARVED COLD
FRONT PUSHES INTO THE AREA ON THURSDAY. PRECIPITATION LOOKS VERY
IFFY...SO WILL KEEP ONLY VERY SMALL POPS WITH THE FRONT.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
SOME RESIDUAL MOISTURE REMAINS IN PLACES AS WEAK SURFACE HIGH
PRESSURE BUILDS OVER THE FORECAST AREA. BY DAY 7 MODELS SHOW SHOW
SOME MODEST SPREAD WITH TROUGH DIGGING INTO THE UPPER MIDWEST WITH
BAROCLINIC APPROACHING FROM THE WEST. BOTH GFS AND EURO MODEL
GENERALLY CLOSE WITH TIMING THE NEXT FEATURE ACROSS. FOLLOWED HPC
POP AND TEMP TRENDS WITH MINOR ADJUSTMENTS.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
GENERALLY PREDOMINATE VFR CONDITIONS EXPECTED THROUGH THIS AFTN.
FG AT KEKN SHOULD BURN OFF BY 13Z. WIDESPREAD SHRA ASSOCIATED WITH
CIRCULATION WILL STRUGGLE TO MAKE INROADS E INTO THE AREA THIS
MORNING. EVEN SO...STILL THINK SCT SHRA A GOOD BET THIS
MORNING...ESPECIALLY ALONG AND W OF OH RVR. HAVE SOME VCSH IN
MOST TAF SITES. AS DAY PROGRESSES...EXPECT COVERAGE TO INCREASE
ONCE AGAIN AIDED ON SFC HEATING. KEPT VFR SHRA VCTS AT THIS
DISTANCE THOUGH AS CONFIDENCE ON TIMING OF ANY TERMINAL GETTING
HIT IS LOW.
ACTIVITY WANES WITH SUNSET BUT STILL ISO TO SCT SHRA EXPECTED
TONIGHT. GRADUALLY BRING CIGS DOWN INTO MVFR RANGE AS LLVL
MOISTURE SHIELD ENCROACHES UPON THE AREA. ENOUGH DOWNSLOPING MAY
EXIST THOUGH TO KEEP KCRW/KCKB IN LOW VFR. COULD ALSO SEE SOME IFR
CIGS ON THE EASTERN SLOPES ON SE UPSLOPE FLOW.
THE FLOW ALOFT WILL BECOME MODERATE TDY...WHEN SOME GUSTS ARE
POSSIBLE AT BKW.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z TUESDAY...
FORECAST CONFIDENCE: MEDIUM TO HIGH.
ALTERNATE SCENARIOS: TIMING OF SHOWERS AND THUNDERSTORMS COULD
VARY. STRATUS TONIGHT COULD VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22
EDT 1HRLY 07 08 09 10 11 12 13 14 15 16 17 18
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H M H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY M M L H H H H H H H H H
PKB CONSISTENCY L L H H H H H M H H H H
CKB CONSISTENCY H H H H H H H M H H H H
AFTER 12Z TUESDAY...
IFR IN HEAVY SHOWERS AND THUNDERSTORMS POSSIBLE WITH THE REMNANTS OF
TROPICAL STORM ISAAC AT TIMES THROUGH TUESDAY NIGHT.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR WVZ010-011-020-031.
OH...FLASH FLOOD WATCH THROUGH THIS EVENING FOR OHZ066-067-076.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30
NEAR TERM...30
SHORT TERM...RPY
LONG TERM...KMC
AVIATION...30
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1007 AM EDT MON SEP 3 2012
.SYNOPSIS...
THE REMNANTS OF ISAAC WILL CONTINUE TO IMPACT THE REGION TODAY
THROUGH WEDNESDAY WITH DEEP TROPICAL MOISTURE AND DAILY WIDESPREAD
SHOWERS AND THUNDERSTORMS WITH LOCALLY HEAVY RAIN. DRIER AIR WILL
FINALLY PUSH INTO THE AREA BY FRIDAY AS A SERIES OF COLD FRONTS
DROP SOUTHEAST INTO THE REGION.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1002 AM EDT MONDAY...
EARLY MORNING PATCHY FOG HAS DISSIPATED IN MOST AREA. JUST A FEW
SMALL POCKETS REMAIN...HOWEVER THESE TOO WILL ERODE BY NOON.
PRECIPITATION ACROSS THE AREA IS MINIMAL. KFCX 88D SHOWING SOME
ISOLATED SHOWERS NEAR AND EAST OF LYNCHBURG VA...AND ALSO A FEW
MAKING THEIR WAY INTO THE NORTHERN MOUNTAINS OF NORTH CAROLINA
FROM NORTHEAST TENNESSEE. THE EXPECTATION IS FOR THIS TO BE THE
NORM THROUGH AROUND NOON. STARTING IN THE EARLY
AFTERNOON...DAYTIME HEATING WILL YIELD ANOTHER RAPID DEVELOPMENT
AND GENEROUS COVERAGE OF SHOWERS AND STORMS ACROSS THE REGION.
HAVE TWEAKED POP AND WEATHER GRIDS TO REFLECT THIS LATEST
EXPECTATION. ALSO HAVE TWEAKED HOURLY TEMPERATURE...DEW
POINT...SKY COVER AND WINDS TO REFLECT THE LATEST OBSERVATIONS AND
EXPECTED TRENDS INTO THE EARLY AFTERNOON.
AS OF 450 AM EDT MONDAY...
WATER VAPOR LOOP SHOWED UPPER LOW OVER EXTREME SOUTHWEST OHIO. AT
THE SURFACE...THE 08Z MSAS ANALYSIS HAD THE LOW OVER THE
KENTUCKY/ILLINOIS/INDIANA BORDER. ALL MODELS OPEN UP THE UPPER LOW
DURING THE NEXT 24 HOURS. SUSPECT EVEN THE SHORT RANGE GUIDANCE
MAY BE A LITTLE ON THE SLOW SIDE WITH THE EVOLUTION OF THE UPPER
SYSTEM...SINCE AN MCS OVER MISSISSIPPI AND ALABAMA MAY HAVE
ALREADY BROKEN OFF A PIECE OF VORTICITY FROM THE MAIN UPPER LOW.
THE MAIN NORTHERN PART OF THE UPPER SYSTEM IS FORECAST TO TRACK
TOWARD PENNSYLVANIA AND THE NORTHERN JET STREAM.
REGIONAL RADARS INDICATED WIDESPREAD SHOWERS AROUND THE UPPER LOW.
MODELS HAVE THIS PRECIPITATION EDGING SLOWLY EAST THIS MORNING. SO
THROUGH NOON HAVE THE HIGHER PROBABILITY OF PRECIPITATION IN THE
FAR WESTERN COUNTY WARNING AREA. EXPECT COVERAGE TO JUST BE
ISOLATED THROUGH MID MORNING FOR THE REST OF THE FORECAST AREA.
WIDESPREAD PRECIPITATION IS EXPECTED THIS AFTERNOON AND EVENING.
SREF AND LOCAL WRF ALONG WITH OTHER GUIDANCE WAS FOCUSING BEST
THREAT OF HEAVY RAIN ALONG THE SOUTHERN BLUE RIDGE...ESPECIALLY IN
THE NORTHWEST NORTH CAROLINA MOUNTAINS. GIVEN THE AIR MAS IS STILL
VERY TROPICAL WITH PRECIPITABLE WATER VALUES IN THE 1.5 TO 2.2
INCH RANGE HAVE LOCALLY HEAVY RAIN MENTIONED FOR ALL PARTS OF THE
FORECAST AREA THIS AFTERNOON AND EVENING.
FFG IS LOWEST IN THE NEW RIVER VALLEY AND ALONG THE FOOTHILLS OF
THE BLUE RIDGE FROM PATRICK AND HENRY COUNTIES DOWN TO WILKES AND
YADKIN COUNTIES. WILL CONTINUE TO ASSESS ANY FLASH FLOOD THREAT
DURING THE MORNING.
ANTICIPATE MINIMAL CHANGE IN TEMPERATURES FROM PAST FEW DAYS.
STAYED CLOSE TO PERSISTENCE FOR MAXIMUM TEMPERATURES TODAY AND
LOWS TONIGHT...WHICH ENDS UP BEING ON THE WARM SIDE OF GUIDANCE.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 254 AM EDT MONDAY...
REMNANTS OF ISAAC UPPER LEVEL TROUGH OPENS ON TUESDAY AND SLOWLY
MOVES OVER THE REGION TUESDAY AND WEDNESDAY. THE TROUGH WILL KEEP
BULK OF THE RAIN OVER THE MOUNTAINS TUESDAY AFTERNOON THEN ALONG THE
BLUE RIDGE AND FOOTHILL COUNTIES TUESDAY EVENING. TUESDAY LOOKS TO
BE THE BETTER DAY FOR SEVERE WEATHER WITH A LOW LEVEL JET CROSSING
THE REGION. CAN NOT RULE OUT STRONG TO SEVERE STORMS WITH A FEW
SUPERCELLS TRACKING ACROSS THE AREA. MOVEMENT OF THESE STORMS WILL
BE RELATIVELY SLOW AND AROUND 20-30 MPH. STRONG TO SEVERE STORMS
WILL BE HIGHLY DEPENDENT ON HEATING THROUGH THE DAY.
THE UPPER LEVEL TROUGH WILL MOVE TO THE BLUE RIDGE WEDNESDAY WITH A
LINE OF SHOWERS STARTING NEAR THE BLUE RIDGE IN THE
AFTERNOON...MOVING EAST INTO THE PIEDMONT IN THE EVENING. STRONG TO
SEVERE STORMS ARE POSSIBLE BUT THE BIGGER THREAT WILL BE EAST OF THE
AREA AND ACROSS THE COASTAL PIEDMONT OF THE MID ATLANTIC REGION.
WEAK HIGH PRESSURE BUILDS IN WEDNESDAY...PUSHING THE TROPICAL AIR MASS
OFF TO THE EAST.
AFTERNOON TEMPERATURES WILL BE NEAR NORMAL TUESDAY AND WEDNESDAY
WHILE OVERNIGHTS CONTINUE TO BE MUGGY AND ABOVE NORMAL.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 1230 PM EDT SUNDAY...
DEEP TROPICAL MOISTURE ASSOCIATED WITH THE REMNANT OF ISAAC WILL
FINALLY GET BOOTED SE DURING THURSDAY AHEAD OF AN INITIAL WEAK COLD
FRONT THAT WILL DROPPING SE IN ADVANCE OF A DEVELOPING ERN 5H TROF.
HOWEVER STILL ENOUGH LIFT WITH THE RESIDUAL SHEAR AXIS AND WEAK
SURFACE TROF TO PROMPT ADDITIONAL SHRA WED NIGHT WITH PERHAPS YET
ANOTHER ORGANIZED BAND ESPCLY EAST ON THURSDAY. THUS KEPT IN HIGH
CHANCE POPS INTO THURSDAY WHICH MAY NEED TO GO HIGHER IN LATER
UPDATES. BOUNDARY MAY TEND TO EDGE SOUTH OF THE AREA DURING FRIDAY
BEFORE THE FLOW STARTS TO BACK AGAIN AHEAD OF A MORE POTENT WAVE
ROUNDING THRU THE GREAT LAKES COLD POOL SAT.
THIS FEATURE SHOULD PUSH A STRONGER SECONDARY COLD FRONT TOWARD
THE APPALACHIANS SAT NIGHT INTO SUNDAY WITH A ANOTHER ROUND OF
SHRA/TSRA AS DEEPER MOISTURE MAKES A QUICK RETURN. JUST HOW FAST
THE FRONT MOVES EAST IFFY GIVEN HINT OF A 5H CUTOFF DEVELOPING
OVER THE OHIO VALLEY BY SUNDAY SO FOLLOWING A BIT OF A BLEND GIVEN
UNCERTAINTY NEXT WEEKEND.
OTRW APPEARS ENOUGH DRYING TO BASICALLY CUT POPS LATER THU NIGHT
THRU FRIDAY NIGHT...THEN RETURNING TO CHANCE COVERAGE FROM WEST TO
EAST LATER SATURDAY THRU SUNDAY. TEMPS TO REMAIN WARM/MUGGY THU
WITH HIGHS MOSTLY IN THE 80S INTO FRIDAY ALTHOUGH A BIT LESS
HUMID. MAY SEE THINGS COOL OFF SOME WITH SHRA SAT BUT MORE SO
SUNDAY PENDING THE FRONTAL TIMING WITH HIGHS LOW/MID 70S WEST AND
LOW 80S EAST.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
AS OF 740 AM EDT MONDAY...
MID LEVEL CLOUDS WILL LIMIT THE EXTENT OF FOG THIS MORNING...BUT
STRATUS WITH IFR CEILINGS DEVELOPED OVERNIGHT ACROSS THE REGION.
EXPECT CEILINGS TO LIFT TO MVFR BY 15Z/11AM THEN VFR BY 17Z/1PM.
HAVE USED THE LOCAL WRF AND HRRR FOR TIMING OF WHEN THUNDERSTORMS
WILL DEVELOP THIS AFTERNOON. THESE MODELS HAVE STORMS INITIALLY DEVELOPING
BETWEEN 19Z/3PM AND 21Z/5PM. NUMEROUS THUNDERSTORMS WILL CONTINUE
INTO THE EVENING...THEN COVERAGE WILL DIMINISH AFTER 00Z/8PM. VERY
HEAVY RAIN IS LIKELY WITH ANY OF THE STRONGER STORMS WHICH WILL
RESULT IN MVFR TO IFR VISIBILITIES.
TROPICAL PATTERN WILL CONTINUE THROUGH THURSDAY WITH THE REMNANTS
OF ISAAC SLOWLY APPROACHING THE AREA. ANTICIPATE PRIMARILY VFR
CONDITIONS WITH BRIEF IFR/MVFR CONDITIONS UNDER ANY STRONGER
SHOWERS OR STORMS. LATE NIGHT AND EARLY MORNING IFR/MVFR MOUNTAIN
AND RIVER VALLEY FOG IS ALSO EXPECTED.
BY THURSDAY NIGHT INTO EARLY FRIDAY...A COLD FRONT WILL SWEEP
THROUGH THE AREA WITH A SURGE OF DRIER AIR BEHIND IT BY FRIDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/DS
SHORT TERM...RCS
LONG TERM...JH
AVIATION...AMS/KM
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
748 AM EDT MON SEP 3 2012
.SYNOPSIS...
THE REMNANTS OF ISAAC WILL CONTINUE TO IMPACT THE REGION TODAY
THROUGH WEDNESDAY WITH DEEP TROPICAL MOISTURE AND DAILY WIDESPREAD
SHOWERS AND THUNDERSTORMS WITH LOCALLY HEAVY RAIN. DRIER AIR WILL
FINALLY PUSH INTO THE AREA BY FRIDAY AS A SERIES OF COLD FRONTS
DROP SOUTHEAST INTO THE REGION.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 450 AM EDT MONDAY...
WATER VAPOR LOOP SHOWED UPPER LOW OVER EXTREME SOUTHWEST OHIO. AT
THE SURFACE...THE 08Z MSAS ANALYSIS HAD THE LOW OVER THE
KENTUCKY/ILLINOIS/INDIANA BORDER. ALL MODELS OPEN UP THE UPPER LOW
DURING THE NEXT 24 HOURS. SUSPECT EVEN THE SHORT RANGE GUIDANCE
MAY BE A LITTLE ON THE SLOW SIDE WITH THE EVOLUTION OF THE UPPER
SYSTEM...SINCE AN MCS OVER MISSISSIPPI AND ALABAMA MAY HAVE
ALREADY BROKEN OFF A PIECE OF VORTICITY FROM THE MAIN UPPER LOW.
THE MAIN NORTHERN PART OF THE UPPER SYSTEM IS FORECAST TO TRACK
TOWARD PENNSYLVANIA AND THE NORTHERN JET STREAM.
REGIONAL RADARS INDICATED WIDESPREAD SHOWERS AROUND THE UPPER LOW.
MODELS HAVE THIS PRECIPITATION EDGING SLOWLY EAST THIS MORNING. SO
THROUGH NOON HAVE THE HIGHER PROBABILITY OF PRECIPITATION IN THE
FAR WESTERN COUNTY WARNING AREA. EXPECT COVERAGE TO JUST BE
ISOLATED THROUGH MID MORNING FOR THE REST OF THE FORECAST AREA.
WIDESPREAD PRECIPITATION IS EXPECTED THIS AFTERNOON AND EVENING.
SREF AND LOCAL WRF ALONG WITH OTHER GUIDANCE WAS FOCUSING BEST
THREAT OF HEAVY RAIN ALONG THE SOUTHERN BLUE RIDGE...ESPECIALLY IN
THE NORTHWEST NORTH CAROLINA MOUNTAINS. GIVEN THE AIR MAS IS STILL
VERY TROPICAL WITH PRECIPITABLE WATER VALUES IN THE 1.5 TO 2.2
INCH RANGE HAVE LOCALLY HEAVY RAIN MENTIONED FOR ALL PARTS OF THE
FORECAST AREA THIS AFTERNOON AND EVENING.
FFG IS LOWEST IN THE NEW RIVER VALLEY AND ALONG THE FOOTHILLS OF
THE BLUE RIDGE FROM PATRICK AND HENRY COUNTIES DOWN TO WILKES AND
YADKIN COUNTIES. WILL CONTINUE TO ASSESS ANY FLASH FLOOD THREAT
DURING THE MORNING.
ANTICIPATE MINIMAL CHANGE IN TEMPERATURES FROM PAST FEW DAYS.
STAYED CLOSE TO PERSISTENCE FOR MAXIMUM TEMPERATURES TODAY AND
LOWS TONIGHT...WHICH ENDS UP BEING ON THE WARM SIDE OF GUIDANCE.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 254 AM EDT MONDAY...
REMNANTS OF ISAAC UPPER LEVEL TROUGH OPENS ON TUESDAY AND SLOWLY
MOVES OVER THE REGION TUESDAY AND WEDNESDAY. THE TROUGH WILL KEEP
BULK OF THE RAIN OVER THE MOUNTAINS TUESDAY AFTERNOON THEN ALONG THE
BLUE RIDGE AND FOOTHILL COUNTIES TUESDAY EVENING. TUESDAY LOOKS TO
BE THE BETTER DAY FOR SEVERE WEATHER WITH A LOW LEVEL JET CROSSING
THE REGION. CAN NOT RULE OUT STRONG TO SEVERE STORMS WITH A FEW
SUPERCELLS TRACKING ACROSS THE AREA. MOVEMENT OF THESE STORMS WILL
BE RELATIVELY SLOW AND AROUND 20-30 MPH. STRONG TO SEVERE STORMS
WILL BE HIGHLY DEPENDENT ON HEATING THROUGH THE DAY.
THE UPPER LEVEL TROUGH WILL MOVE TO THE BLUE RIDGE WEDNESDAY WITH A
LINE OF SHOWERS STARTING NEAR THE BLUE RIDGE IN THE
AFTERNOON...MOVING EAST INTO THE PIEDMONT IN THE EVENING. STRONG TO
SEVERE STORMS ARE POSSIBLE BUT THE BIGGER THREAT WILL BE EAST OF THE
AREA AND ACROSS THE COASTAL PIEDMONT OF THE MID ATLANTIC REGION.
WEAK HIGH PRESSURE BUILDS IN WEDNESDAY...PUSHING THE TROPICAL AIR MASS
OFF TO THE EAST.
AFTERNOON TEMPERATURES WILL BE NEAR NORMAL TUESDAY AND WEDNESDAY
WHILE OVERNIGHTS CONTINUE TO BE MUGGY AND ABOVE NORMAL.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 1230 PM EDT SUNDAY...
DEEP TROPICAL MOISTURE ASSOCIATED WITH THE REMNANT OF ISAAC WILL
FINALLY GET BOOTED SE DURING THURSDAY AHEAD OF AN INITIAL WEAK COLD
FRONT THAT WILL DROPPING SE IN ADVANCE OF A DEVELOPING ERN 5H TROF.
HOWEVER STILL ENOUGH LIFT WITH THE RESIDUAL SHEAR AXIS AND WEAK
SURFACE TROF TO PROMPT ADDITIONAL SHRA WED NIGHT WITH PERHAPS YET
ANOTHER ORGANIZED BAND ESPCLY EAST ON THURSDAY. THUS KEPT IN HIGH
CHANCE POPS INTO THURSDAY WHICH MAY NEED TO GO HIGHER IN LATER
UPDATES. BOUNDARY MAY TEND TO EDGE SOUTH OF THE AREA DURING FRIDAY
BEFORE THE FLOW STARTS TO BACK AGAIN AHEAD OF A MORE POTENT WAVE
ROUNDING THRU THE GREAT LAKES COLD POOL SAT.
THIS FEATURE SHOULD PUSH A STRONGER SECONDARY COLD FRONT TOWARD
THE APPALACHIANS SAT NIGHT INTO SUNDAY WITH A ANOTHER ROUND OF
SHRA/TSRA AS DEEPER MOISTURE MAKES A QUICK RETURN. JUST HOW FAST
THE FRONT MOVES EAST IFFY GIVEN HINT OF A 5H CUTOFF DEVELOPING
OVER THE OHIO VALLEY BY SUNDAY SO FOLLOWING A BIT OF A BLEND GIVEN
UNCERTAINTY NEXT WEEKEND.
OTRW APPEARS ENOUGH DRYING TO BASICALLY CUT POPS LATER THU NIGHT
THRU FRIDAY NIGHT...THEN RETURNING TO CHANCE COVERAGE FROM WEST TO
EAST LATER SATURDAY THRU SUNDAY. TEMPS TO REMAIN WARM/MUGGY THU
WITH HIGHS MOSTLY IN THE 80S INTO FRIDAY ALTHOUGH A BIT LESS
HUMID. MAY SEE THINGS COOL OFF SOME WITH SHRA SAT BUT MORE SO
SUNDAY PENDING THE FRONTAL TIMING WITH HIGHS LOW/MID 70S WEST AND
LOW 80S EAST.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AS OF 740 AM EDT MONDAY...
MID LEVEL CLOUDS WILL LIMIT THE EXTENT OF FOG THIS MORNING...BUT
STRATUS WITH IFR CEILINGS DEVELOPED OVERNIGHT ACROSS THE REGION.
EXPECT CEILINGS TO LIFT TO MVFR BY 15Z/11AM THEN VFR BY 17Z/1PM.
HAVE USED THE LOCAL WRF AND HRRR FOR TIMING OF WHEN THUNDERSTORMS
WILL DEVELOP THIS AFTERNOON. THESE MODELS HAVE STORMS INITIALLY DEVELOPING
BETWEEN 19Z/3PM AND 21Z/5PM. NUMEROUS THUNDERSTORMS WILL CONTINUE
INTO THE EVENING...THEN COVERAGE WILL DIMINISH AFTER 00Z/8PM. VERY
HEAVY RAIN IS LIKELY WITH ANY OF THE STRONGER STORMS WHICH WILL
RESULT IN MVFR TO IFR VISIBILITIES.
TROPICAL PATTERN WILL CONTINUE THROUGH THURSDAY WITH THE REMNANTS
OF ISAAC SLOWLY APPROACHING THE AREA. ANTICIPATE PRIMARILY VFR
CONDITIONS WITH BRIEF IFR/MVFR CONDITIONS UNDER ANY STRONGER
SHOWERS OR STORMS. LATE NIGHT AND EARLY MORNING IFR/MVFR MOUNTAIN
AND RIVER VALLEY FOG IS ALSO EXPECTED.
BY THURSDAY NIGHT INTO EARLY FRIDAY...A COLD FRONT WILL SWEEP
THROUGH THE AREA WITH A SURGE OF DRIER AIR BEHIND IT BY FRIDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...RCS
LONG TERM...JH
AVIATION...AMS/KM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
649 AM CDT MON SEP 3 2012
.SHORT TERM...TODAY THROUGH WEDNESDAY
327 AM CDT MON SEP 3 2012
CONCERNS CENTER AROUND RAIN CHANCES THROUGH THE PERIOD/SEVERE
CHANCES TODAY.
BUSY WATER VAPOR LOOP THIS MORNING WITH A MID LEVEL TROUGH MOVING
THROUGH MN AND THEN A MORE VIGOROUS CLOSED LOW/TROUGH MOVING THROUGH
ALBERTA CANADA/MONTANA. AT THE SURFACE...A COLD FRONT EXTENDED FROM
NEAR INTERNATIONAL FALLS TO SAINT CLOUD MN...AND THEN SOUTHWESTWARD
TO SIOUX FALLS SD. RADAR MOSAIC SHOWING BAND OF SCATTERED
SHOWERS/THUNDERSTORMS AHEAD OF THE FRONT FROM NEAR THE ARROWHEAD OF MN
INTO NORTHWEST WI AND EAST CENTRAL MN. RAP SHOWS THIS ACTIVITY WAS
ON THE EASTERN PERIPHERY OF FAIRLY DECENT AXIS OF 850MB MOISTURE
TRANSPORT. OTHERWISE...TEMPERATURES ACROSS THE FORECAST AREA AT 3 AM
WERE HOLDING IN THE UPPER 60S/LOWER 70S WITH DEWPOINTS IN THE MIDDLE
60S.
SUNDAY EVENING MODEL RUNS SHOWING FAIRLY DECENT AGREEMENT THROUGH
THE SHORT TERM PERIOD.
LOOK FOR THE MID-LEVEL SHORTWAVE AND ASSOCIATED SURFACE COLD FRONT
OVER MN TO SINK SLOWLY SOUTHEAST INTO THE AREA TODAY...WHILE
UNDERGOING SOME WEAKENING. RAP/NAM MODELS SHOWING BEST 850MB
MOISTURE TRANSPORT AHEAD OF THE TROUGH/FRONT PUSHING EAST OF THE
AREA BY LATER THIS MORNING. HOWEVER...MODELS FAIRLY PERSISTENT IN
PRODUCING SCATTERED SHOWERS AND THUNDERSTORM TODAY ACROSS THE
AREA...WITH BETTER CHANCES HEADED INTO THE AFTERNOON GIVEN PEAK
HEATING/HIGHER DEW POINT POOLING AND 0-3KM MUCAPE PEAKING IN THE
3000-5000J/KG RANGE WITH DOWNDRAFT CAPE IN THE 1500-2000J/KG RANGE.
UPPER LEVEL DYNAMICS HELP ALSO GIVEN RIGHT ENTRANCE REGION OF 300MB
JET PER THE NAM BY THIS AFTERNOON. MODEL SOUNDINGS SHOW INVERTED-V
AND ALTHOUGH 0-3KM BULK SHEAR FAIRLY LIMITED...DOWNDRAFT CAPE HAS ME
A BIT CONCERNED FOR DAMAGING WIND POTENTIAL. WILL HAVE TO KEEP A
VERY CLOSE EYE ON THINGS TODAY. OTHERWISE...ANOTHER UNSEASONABLY
WARM DAY ON TAP WITH HIGHS PUSHING INTO THE 80S ONCE AGAIN.
LOOKING FOR THE BULK OF THE SHOWERS/THUNDERSTORMS TO MOVE SOUTHEAST
OF THE AREA THIS EVENING...BUT THEN MODELS SHOWING ANOTHER MID-LEVEL
TROUGH PUSHING ACROSS THE PLAINS TOWARD THE AREA AFTER MIDNIGHT WITH
WEAK ISENTROPIC LIFT AND MOISTURE TRANSPORT. KEPT SMALLER 20-30 POP
SHRA/T CHANCE TO COVER THIS WEAKER SIGNAL.
GFS AND NAM HINTING AT SOME SORT OF WEAK TROUGH RIPPLING THROUGH
FAIRLY HIGH-ZONAL FLOW ALOFT ON TUESDAY WITH SOME MINOR TIMING
DIFFERENCES NOTED. GIVEN THIS RATHER NONDESCRIPT SIGNAL...WILL STICK
WITH SLIGHT CHANCE OF SHRA/TS.
A MORE VIGOROUS MID-LEVEL CLOSED LOW SWINGS EAST ACROSS SOUTHERN
CANADA TUESDAY NIGHT/WEDNESDAY WITH TROUGH AXIS AND ASSOCIATED
STRONG SURFACE COLD FRONT SWINGING EAST ACROSS THE AREA. THIS HAS BEEN A
RATHER CONSISTENT SIGNAL THE LAST FEW DAYS NOW...SO FEEL COMFORTABLE
WITH HIGHER-END CHANCE TO LIKELY SHRA/TS. GIVEN TIMING OF THE
FRONTAL PASSAGE THROUGH THE AREA WEDNESDAY MORNING...SEVERE THREAT
LOOKS TO BE SOUTHEAST OF THE AREA DURING THE AFTERNOON.
OTHERWISE...MODEL SOUNDINGS SHOWING GOOD MIXING/DRYING BEHIND THE
FRONT WEDNESDAY AFTERNOON ON BREEZY NORTHWEST WINDS IN THE 15 TO 30
MPH RANGE. TEMPERATURES WILL ALSO RETURN TO NEAR SEASONAL NORMALS IN
THE MID 70S TO LOWER 80S.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
327 AM CDT MON SEP 3 2012
FAIRLY GOOD AGREEMENT BETWEEN THE GFS AND ECMWF IN THE WEDNESDAY
NIGHT THROUGH SATURDAY TIME FRAME. WEDNESDAY NIGHT/THURSDAY LOOK
COOLER AND DRY AS MID/UPPER LEVEL TROUGH SETTLES INTO THE AREA. LOWS
WEDNESDAY NIGHT EXPECTED TO FALL INTO THE UPPER 40S TO LOWER 50S WITH
HIGHS ON THURSDAY IN THE 70S. SHRA/TS CHANCES RETURN TO THE AREA
THURSDAY NIGHT THROUGH FRIDAY NIGHT AS AS ANOTHER MID-LEVEL TROUGH
DROPS THROUGH THE REGION WITH A REINFORCING SHOT OF COOLER AND MORE
AUTUMN-LIKE AIR. EXPECTING HIGHS ON FRIDAY IN THE UPPER 60S TO
MIDDLE 70S WITH LOWS IN THE UPPER 40S TO MIDDLE 50S. SATURDAY
CONTINUES TO BE COOL BUT DRY WITH HIGHS IN THE UPPER 60S AND LOWER
70S AFTER OVERNIGHT LOWS IN THE UPPER 40S TO LOWER 50S. APPEARS
SUNDAY WILL SEE SOME WARMING AS MID-LEVEL HEIGHTS BUILD IN RESPONSE
TO RIDGE BUILDING IN FROM THE PLAINS. LOOK FOR HIGHS IN THE LOWER TO
MIDDLE 70S.
&&
.AVIATION...TODAY AND TONIGHT
649 AM CDT MON SEP 3 2012
THE MAIN FORECAST CONCERNS AT THE TAF SITES ARE WITH THE
THUNDERSTORM CHANCES TODAY INTO TONIGHT AS A COLD FRONT MOVES
THROUGH THE REGION. ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS HAVE DEVELOPED THIS MORNING FROM NORTHWEST WISCONSIN
DOWN INTO SOUTH CENTRAL MINNESOTA AND WILL MOVE EAST TOWARD
RST/LSE THIS MORNING. CONDITIONS ARE MAINLY VFR AT THE MOMENT WITH
CEILINGS UP AROUND 8-12KFT...BUT IF ANY OF THESE SHOWERS/STORMS
HAPPEN TO HIT RST OR LSE THERE COULD BE SOME VERY BRIEF VISIBILITY
DROPS TO MVFR OR IFR. VISIBILITY AT RST HAS ALREADY DROPPED DOWN
TO 5SM DUE TO SOME HAZE THAT FORMED THIS MORNING DUE TO THE HIGH
MOISTURE CONTENT AT THE SURFACE. THE SHOWERS/STORMS THIS MORNING
WILL COME TO AN END THIS AFTERNOON AS THE COLD FRONT MOVES THROUGH
AND WINDS COME AROUND TO THE WEST-NORTHWEST. THERE ARE SOME HINTS
THAT MORE STORMS COULD DEVELOP OVERNIGHT...BUT CONFIDENCE IS NOT
HIGH ENOUGH AT THIS POINT TO PUT ANY MENTION IN THE TAFS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
327 AM CDT MON SEP 3 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
300 PM MST MON SEP 3 2012
.SYNOPSIS...
HIGH PRESSURE ALOFT WILL REMAIN CENTERED OVER OR NEAR NEW MEXICO
THROUGH MUCH OF THE UPCOMING WEEK. VERY MOIST AND MODERATELY
UNSTABLE AIR WILL OVERSPREAD THE AREA...WHILE WEAK WEATHER
DISTURBANCES PERIODICALLY MOVE WEST ACROSS NORTHERN MEXICO. AS A
RESULT...EXPECT A RATHER ACTIVE PERIOD OF WEATHER THIS WEEK...WITH
AN ABOVE NORMAL CHANCE FOR MAINLY LATE AFTERNOON AND EVENING
THUNDERSTORMS. LOCALLY HEAVY RAINFALL AND STRONG WINDS ARE LIKELY
WITH THE MORE INTENSE STORMS.
&&
.DISCUSSION...
LATEST RAP ANALYZED A DIFFUSE TROUGH EXTENDING FROM SOUTHERN NM TO
HERMOSILLO MEXICO...THOUGH THIS IS DIFFICULT TO IDENTIFY ON WV
IMAGERY. STRONG STORMS HAVE DEVELOPED IN THE DIFLUENT REGION BETWEEN
THIS TROUGH AND AN ANTICYCLONE CENTERED NEAR THE WHITE MOUNTAINS.
FURTHER NORTH ACROSS THE MOGOLLON RIM...OROGRAPHICALLY-INDUCED
SHOWERS AND THUNDERSTORMS HAVE ALSO FORMED BUT CONTINUE TO DRIFT
NORTHEASTWARD TOWARDS THE CO PLATEAU WITHIN A 10 KT MEAN LAYER FLOW.
EARLIER MOISTURE SURGE ALONG THE GOC AND ACROSS YUMA AND THE
IMPERIAL VALLEY YIELDED HEAT INDICES BETWEEN 110 AND 115
DEGREES...BUT HAVE SINCE LOWERED AS THE ATMOSPHERE MIXES OUT.
LATEST MESOANALYSIS SHOWS MODERATELY STRONG CONVECTIVE INHIBITION
ACROSS MUCH OF THE FORECAST AREA...LARGELY DUE TO A RIDGE AND THE
ASSOCIATED WARM/DRY AIR IN THE 800-700 MB LAYER. MODEL SOUNDINGS
INDICATE THAT THIS LAYER WILL MOISTEN ACROSS WESTERN AZ THIS
AFTERNOON...WHICH WILL HELP TO ERODE THE CIN AND INITIATE ISOLATED
CONVECTION. NMM-B BASED WRF FROM UNIV OF AZ APPEARS TO HAVE THE BEST
HANDLE ON THE SHORT-TERM EVOLUTION AND SUGGESTS STORMS WILL FIRE
ACROSS YUMA AND LA PAZ COUNTIES THIS AFTERNOON. ISOLATED ACTIVITY IN
THE IMPERIAL VALLEY ALSO CANNOT BE RULED OUT...GIVEN THE
SOUTHWESTERLY STEERING FLOW AND PRESENCE OF CB/TCU ON VISIBLE
SATELLITE ALONG THE BAJA SPINE. ACROSS THE PHOENIX METRO AREA...THE
MAIN IMPACT APPEARS TO BE THE POTENTIAL BLOWING DUST FROM
THUNDERSTORMS TO THE SOUTH...THOUGH POPS REMAIN 5 TO 10 PERCENT
ABOVE THE CLIMATOLOGICAL AVERAGE.
&&
.PREVIOUS DISCUSSION...
IN THE SHORT TERM (MONDAY-WEDNESDAY)...EXPECT A DAY TO DAY INCREASE
IN STORM ACTIVITY...ESPECIALLY OVER AZ PORTION OF THE CWA. VERY
MOIST AIR MASS CURRENTLY EXISTS OVER NORTHWEST MEXICO. SYNOPTIC
PATTERN...WITH RATHER STRONG TROUGH OF LOW PRESSURE MOVING EAST
ACROSS SOUTH-CENTRAL CANADA WHILE A TROPICAL DISTURBANCE (NOW TS
JOHN) MOVES WEST JUST OFF THE SOUTHERN END OF BAJA
CALIFORNIA...CERTAINLY SUPPORTS A MOISTURE INCREASE OVER OUR
AREA...AND THE GFS/ECMWF/NAM CERTAINLY AGREE THE ATMOSPHERE WILL
MOISTEN SIGNIFICANTLY DURING THE NEXT 36 HRS.
WITH ATMOSPHERIC MOISTENING CONTINUING ON TUESDAY (ANOMALOUSLY HIGH
PRECIPITABLE WATER NEAR 2" BY THEN) AND MORE DIFLUENT UPPER LEVEL
FLOW OVER SOUTHEAST AZ BY TUESDAY AFTN...PRECIP CHANCE WILL BE A BIT
GREATER TUESDAY EVENING... ESPECIALLY OVER SOUTH-CENTRAL AZ. VERY
MOIST AND MODERATELY UNSTABLE ATMOSPHERE REMAINS IN PLACE ON
WEDNESDAY...AND PRECIP CHANCES WILL BE ENHANCED AS A WEAK WEATHER
DISTURBANCE MOVES WEST ACROSS SONORA. WITH SUCH HIGH ATMOSPHERIC
MOISTURE CONTENT...DECENT CAPE...AND WEAK STEERING FLOW...LOCALLY
HEAVY RAINFALL CAN BE EXPECTED...THOUGH STRONG/DAMAGING WINDS WILL
ALSO BE POSSIBLE.
IN THE EXTENDED PERIOD(THURSDAY-SUNDAY)...NUMERICAL MODELS INDICATE
ATMOSPHERE WILL REMAIN ANOMALOUSLY MOIST AND MODERATELY UNSTABLE
WHILE WEAK WEATHER DISTURBANCE CONTINUE TO AFFECT THE DESERT
SOUTHWEST. WENT WITH SLIGHT CHANCE POPS DURING THE LATE AFTN/EVENING
HOURS FOR SOUTH-CENTRAL AZ EACH DAY...BUT WOULD NOT BE SURPRISED IF
PRECIP CHANCES WILL ACTUALLY BE SOMEWHAT HIGHER THAN CURRENTLY
PORTRAYED.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...
THROUGH 06Z TUE...INCREASING CLOUDS BECOMING SCT-BKN AOA 14 THSD MSL
LATE IN THE AFTERNOON AND EVENING...WITH POSSIBLE ISOLATED
SHWRS/TSTMS. WEST WIND 5 TO 15 KNOTS...BUT VARIABLE AND GUSTY WITH
CONVECTIVE OUTFLOW BOUNDARIES IF NEARBY CONVECTION DEVELOPS. FROM
06Z TUE TO 19Z TUE...SCT-BKN CLDS AOA 14 THSD MSL. LIGHT WIND UNDER
10 KNOTS.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
THROUGH 06Z TUE...INCREASING CLOUDS BECOMING SCT-BKN AOA 14 THSD MSL
LATE IN THE AFTERNOON AND EVENING...WITH ISOLATED SHWRS/TSTMS. SOUTH
WIND 5 TO 15 KNOTS...BUT VARIABLE AND GUSTY WITH CONVECTIVE OUTFLOW
BOUNDARIES IF NEARBY CONVECTION DEVELOPS. FROM 06Z TUE TO 19Z
TUE...SCT-BKN CLDS AOA 16 THSD MSL. SOUTH WIND 5 TO 15 KNOTS.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
SIGNIFICANT MONSOON MOISTURE WILL COVER THE REGION. A SLIGHT CHANCE
OF AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE MAINLY OVER
SOUTH CENTRAL ARIZONA...PARTICULARLY MOUNTAINS. MINIMUM RELATIVE
HUMIDITIES WILL RANGE FROM 20 TO 25 PERCENT...EXCEPT 15 TO 20
PERCENT IN IN SOUTHEAST CALIFORNIA. RELATIVELY LIGHT WINDS ARE
EXPECTED.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...DG
AVIATION...VASQUEZ
FIRE WEATHER...VASQUEZ
AREA FORECAST DISCUSSION
NWS TUCSON AZ
930 AM MST MON SEP 3 2012
.SYNOPSIS...THERE WILL BE PLENTY OF MOISTURE AROUND FOR SCATTERED
AFTERNOON AND EVENING THUNDERSTORMS AGAIN TODAY...MAINLY SOUTH AND
WEST OF TUCSON. DEEPER MOISTURE WILL MOVE ACROSS THE AREA TUESDAY
AND WEDNESDAY FOR AN UPSWING IN THUNDERSTORM ACTIVITY.
&&
.DISCUSSION...UPPER AIR PLOTS THIS MORNING PLACED MID LEVEL HIGH
OVER W-CNTRL NEW MEXICO WHILE FURTHER UP AROUND 300 MB THE HIGH WAS
OVER NE SONORA MEXICO. THUS WE HAVE WEAK E-SE MID LEVEL FLOW AND A
BIT STRONGER SW FLOW AT 300 MB. PRECIPITABLE WATER VALUES ARE UP A
BIT FROM 24 HOURS AGO...ESPECIALLY OVER THE EASTERN AREAS AND THEY
HAVE INCREASED A LOT OVER SONORA MEXICO AS DEEPER TROPICAL MOISTURE
CONTINUES TO PUSH NORTH ACROSS THE GULF OF CALIFORNIA AND SONORA
MEXICO WHERE OVER 2 INCHES OF PW RESIDES FROM HERMOSILLO S. VALUES
ACROSS SOUTHERN ARIZONA THIS MORNING RANGED FROM 1.30" ALONG AZ/NM
BORDER TO 1.60" IN WESTERN PIMA COUNTY. NO DISCERNIBLE FEATURE ALOFT
CAN BE SEEN ON WATER VAPOR IMAGERY BUT BOTH 12Z NAM/GFS DO SHOW A
WEAK INVERTED TROF OVER CENTRAL SONORA...WHICH THEY BOTH MOVE NORTH
TO THE INTERNATIONAL BORDER THIS AFTERNOON. THE WRF VERSION OF THESE
MODELS ALONG WITH THE LATEST HRRR MODEL RUN ARE INDICATING THAT
SANTA CRUZ AND SOUTHERN COCHISE COUNTY ALONG WITH SOUTHERN PORTIONS
OF THE TOHONO OODHAM NATION WILL BE THE FOCUS FOR STORMS THIS
AFTERNOON INTO THIS EVENING. STILL LOOKING AT WET MICROBURSTS
PRODUCING LOCALLY HEAVY RAIN WHERE RAINFALL AMOUNTS COULD BE IN THE
1-2" RANGE. WITH THIS IN MIND MADE SOME SLIGHT ADJUSTMENTS TO
POP/QPF GRIDS FOR THESE AREAS WITH UPDATE DUE OUT SHORTLY. WILL ALSO
HIGHLIGHT ENHANCED CHANCES FOR FLASH FLOODING FOR THE ABOVE
MENTIONED AREAS IN THE HAZARDOUS WEATHER OUTLOOK. AT THIS TIME DO
NOT BELIEVE AREAL COVERAGE WILL BE WIDESPREAD ENOUGH TO WARRANT FF
WATCH. HIGHS TODAY WILL BE A BIT COOLER VERSUS SUNDAY.
TROPICAL MOISTURE WILL CONTINUE TO PUSH NORTH INTO ARIZONA TUESDAY
AND WEDNESDAY AS TROPICAL STORM JOHN MOVES TO THE WNW INTO COOLER
WATERS WELL OFF BAJA COAST. AS WE HAVE BEEN ADVERTISING FOR A COUPLE
OF DAYS NOW...BOTH TUESDAY AND WEDNESDAY LOOK PRETTY ACTIVE. DUE TO
THE ADDED MOISTURE AND CLOUD COVER...HIGHS TUESDAY AND WEDNESDAY
WILL BE BELOW NORMAL.
&&
.AVIATION...MAIN AREA OF CONCERN FOR SHOWERS AND THUNDERSTORMS THIS
AFTERNOON AND EVENING WILL BE SOUTH AND WEST OF KTUS WHERE THEY WILL
BE MORE NUMEROUS.
SURFACE WIND GENERALLY LESS THAN 10 KTS...EXCEPT FOR GUSTS TO 45 KTS
NEAR SCTD TSRA/SHRA BTWN 03/19Z AND 04/04Z...ESPECIALLY FROM S AND W
OF KTUS. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...EXPECT SCATTERED MAINLY AFTERNOON AND EVENING
SHOWERS AND THUNDERSTORMS THROUGH THE WEEK. ERRATIC AND GUSTY WINDS
CAN BE EXPECTED NEAR ANY THUNDERSTORMS THAT DEVELOP.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/TUCSON
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
253 PM MDT MON SEP 3 2012
.SHORT TERM...(TODAY THROUGH TUESDAY NIGHT)
ISSUED AT 252 PM MDT MON SEP 3 2012
JET STREAM REMAINS OVERHEAD WITH STRONGEST JET STREAK HAVING MOVED
WELL EAST OVER SRN MN/NRN IA. CONVECTION CONTINUES TO FAVOR THE
ROAN/TAVAPUTS THIS AFTN IN RESPONSE TO DISTURBANCES MOVING
THROUGH MEAN FLOW AND ALSO FAVORABLE OROGRAPHICS. POT VORT FIELDS
ALSO FAVOR THIS AREA SO EVENTS PLAYING OUT AS EXPECTED. AS HAS
BEEN THE CASE LAST FEW DAYS...BIGGEST CONCERN WILL BE GUSTY
OUTFLOW WINDS REACHING 40 TO 45 MPH AND ALSO SOME SMALL HAIL. DID
EXPECT MORE CONVECTION DOWN SOUTH SINCE AVAILABLE PRECIP TABLE
WATER IS MUCH HIGHER. BELIEVE CONVECTION IS LIMITED FOR TWO
REASONS. FIRST...STEERING FLOW IS ALMOST FROM DUE WEST WHICH IS
NOT THE BEST DIRECTION FOR OROGRAPHICALLY INDUCED CONVECTION.
SECOND...AND MORE IMPORTANTLY...THERE IS NO REAL TRIGGER TO KICK
OFF SOME LIFT LIKE THERE IS UP NORTH.
SO FOR THE REMAINDER OF THE AFTERNOON...SOME MINOR DISCREPANCIES
HAVE CROPPED UP BETWEEN MODELS BUT HRRR IS DOING A REMARKABLE JOB
NAILING DOWN WHERE CONVECTION HAS AND IS OCCURRING. LATEST HRRR
GUIDANCE SUGGESTS SHOWERS AND STORMS WILL DIE DOWN BY 6PM WITH
VERY LITTLE IN THE WAY OF PRECIPITATION AFTER THAT. THIS DOES MAKE
SENSE AS MODELS ALSO CONTINUE TO DRY OUT ATMOSPHERE. FORECAST
FOLLOWS SUIT THOUGH NOT SO DRAMATICALLY WITH CONVECTION ENDING
AROUND SUNSET. CLEAR SKIES WILL BE DOMINANT OVERNIGHT ALLOWING LOW
TEMPS TO BE A BIT COOLER THAN SEEN THE LAST FEW DAYS THOUGH STILL
A DEGREE OR TWO ABOVE NORMAL.
ON TUESDAY ZONAL FLOW SETS UP FROM THE H3 LEVEL TO H7 WHICH
EFFECTIVELY CUTS OFF THE FLOW OF MOISTURE FROM THE SOUTH. THE MUCH
TOUTED DRIER AIR WILL FINALLY ARRIVE IF THE NAM12/GFS40 ARE TO BE
BELIEVED WHICH WILL GREATLY INHIBIT CONVECTION. KEPT POPS AS THEY
WERE WITH SOME VERY ISOLD SHOWERS AND STORMS POSSIBLE OVER SAN
JUANS AND TO SOME EXTENT CENTRAL MOUNTAINS THOUGH TREND IS TO KEEP
LOWERING POP AND QPF AMTS AND COVERAGE. THE REMAINDER OF THE
FORECAST AREA WILL SEE PLENTY OF SUNSHINE WITH SEASONAL
TEMPERATURES EXPECTED. OVERNIGHT...CLEAR SKIES EXPECTED WITH NEAR
NORMAL LOW TEMPERATURES.
.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 252 PM MDT MON SEP 3 2012
SOMEWHAT ACTIVE NORTHERN STREAM THE LAST HALF OF THE WEEK AS
SHORTWAVES ROTATING AROUND A CENTRAL CANADA LOW DROP INTO THE NRN
TIER STATES. FIRST SHORTWAVE MOVES INTO THE UPPER MIDWEST ON
WEDNESDAY... A SECOND DROPS DOWN ACROSS MT WED NIGHT...AND A THIRD
AND STRONGER ONE CLIPS NE CO LATE FRI. A RATHER WEAK WESTERLY UPPER
JET OVERHEAD ON WED STRENGTHENS THU-FRI AS THAT THIRD WAVE
APPROACHES...AND MAY RESULT IN STRONGER SURFACE WINDS ACROSS NE
UT/NW CO. BROAD HIGH PRESSURE DOMINATES THE SOUTHWEST STATES AND
FOUR CORNERS AND WILL BE MAIN INFLUENCE ON SE UT/SW CO. MODELS KEEP
ENOUGH MOISTURE PRESENT FOR ISOLATED TO PERHAPS SCATTERED
THUNDERSTORMS MAINLY OVER THE CENTRAL AND SOUTHERN MTNS THURSDAY.
THE SOUTHWEST UPPER HIGH BUILDS NORTHWEST INTO THE GREAT BASIN FRI
AND SAT AND SHOULD RESULT IN DRIER NW FLOW FOR OUR FORECAST AREA
THIS WEEKEND. MODELS SHOW A PACIFIC TROUGH REACHING THE NORTHWEST
COAST BY MONDAY...SHIFTING THE HIGH EAST AND ALLOWING MONSOONAL
MOISTURE TO RETURN NEXT MONDAY. CONFIDENCE BELOW AVERAGE ON THIS...
HOWEVER...GIVEN MODEL AND RUN-TO-RUN INCONSISTENCIES...SO WILL STAY
CONSERVATIVE WITH POPS FOR MONDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 252 PM MDT MON SEP 3 2012
CONVECTION CONTINUES WITH SOME GUSTY WINDS BEING REPORTED ACROSS
THE AREA. KRIL JUST EXPERIENCED A GUST OF 44 MPH FROM A STORM THAT
IS WELL NORTH OF THE AERODROME. THESE GUSTY WINDS CAN BE EXPECTED
OVER THE NEXT FEW HOURS WITH KEGE AND KASE HAVING THE BEST CHANCE
TO SEE THESE WINDS AND A PASSING SHOWER OR THUNDERSTORM. BRIEF
MVFR IS POSSIBLE FOR THOSE TWO SITES THROUGH 9 PM. REMAINING
AERODROMES SHOULD REMAIN VFR FOR THE NEXT 24 HOURS. THE REST OF
THE STORMS AND SHOWERS SHOULD END AROUND SUNSET GIVING WAY TO
CLEAR SKIES THAT WILL PERSIST THROUGH TOMORROW.
&&
.FIRE WEATHER...
ISSUED AT 252 PM MDT MON SEP 3 2012
WIND IN GENERAL LOOKS TO REMAIN JUST BELOW CRITICAL LEVELS ACROSS
DAGGETT COUNTY AND NORTHERN DUCHESNE COUNTY /FWX ZONES 481 AND 485/
IN NE UT AND MOFFAT COUNTY /FWX ZONE 200/ IN NW CO TUESDAY
AFTERNOON. WIND GUSTS 20-25 MPH ARE PROBABLE DURING PEAK HEATING
TUESDAY AFTERNOON. WHILE LOCAL AREAS MAY SEE CRITICAL CONDITIONS
BELOW 8000-9000 FT DUE TO WIND GUSTS AND LOW RH...DO NOT THINK AREAL
COVERAGE OR DURATION IS ENOUGH TO WARRANT A FIRE WEATHER HIGHLIGHT
FOR NE UT/NW CO AT THIS TIME.
SOME CONCERN THAT WIND GUSTS COULD APPROACH/EXCEED CRITICAL LEVELS
ACROSS NE UT/NW CO ON THU AS A DISTURBANCE APPROACHING FROM THE NW
BEGINS TO STRENGTHEN WINDS ALOFT...WHICH COULD THEN MIX DOWN DURING
PEAK HEATING. HOWEVER...IT APPEARS THAT HUMIDITY WILL REMAIN ABOVE
CRITERIA THU AS MODELS CURRENTLY SHOWING SOME INCREASE IN MOISTURE.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...TGR
LONG TERM...JAD
AVIATION...TGR
FIRE WX...JAD
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1129 AM MDT MON SEP 3 2012
.AVIATION...
VFR CONDITIONS EXPECTED NEXT 24H AT ALL 3 TAF SITES...KCOS...KPUB
AND KALS. WINDS WILL BE DIURNALLY DRIVEN AND LIGHT. THERE IS A
VERY SLIGHT CHANCE OF A WEAK -TSRA AT THE 3 TAF SITES THIS
AFTERNOON BUT PROBABILITY OF OCCURRENCE IS TOO LOW TO MENTION IN
TAF PRODUCTS.
&&
.PREV DISCUSSION... /ISSUED 431 AM MDT MON SEP 3 2012/
SHORT TERM...
(TODAY AND TONIGHT)
RADAR IS STILL PICKING UP SOME ECHOES OVR THE FORECAST AREA...BUT
COVERAGE IS SPOTTY. WV SATELLITE IMAGERY SHOWING A PLUME OF
MSTR ACRS THE STATE THIS MORNING. MODELS SHOW DRIER AIR WORKING
INTO THE AREA FROM THE WEST...BUT REMAINING OVR ERN AREAS. AS A
RESULT...THE FORECAST MODELS HAVE LITTLE IN THE WAY OF PCPN OVR THE
CONTDVD TODAY. HOWEVER...THERE MAY STILL BE ENOUGH RESIDUAL MSTR TO
KEEP SOME ISOLD POPS IN THE FORECAST FOR THAT AREA. OVR THE ERN MTS
AND PLAINS...THE 4KM WRF HAS SOME VERY SPOTTY PCPN OCCURRING THIS
AFTERNOON AND EVENING WITH THE BEST CHANCES BEING ALONG THE SRN
BORDER. THE HRRR IS VERY SIMILAR TO THE 4KM WRF. THE NAM ON THE
OTHER HAND HAS SOME LIGHT PCPN BEING POSSIBLE MOST LOCATIONS OF THE
ERN MTS AND PLAINS. WITH THE MST PLUME STILL EXPECTED TO BE IN
PLACE...WL GO WITH GENERALLY ISOLD POPS ACRS MUCH OF THE SERN
PLAINS. MOST AREAS WILL AGAIN SEE HIGH TEMPS THAT ARE 5-10 DEGREES
ABOVE AVERAGE.
TONIGHT THE MSTR PLUME CONTINUE TO MOVE EAST...BUT CONTINUES TO
LINGER OVR THE FAR SERN AREAS. BY MIDNIGHT MOST AREAS SHOULD SEE AN
END TO THE PCPN...BUT THE MODELS DO CONTINUE TO HANG ON TO SOME PCPN
INTO THE LATE NIGHT HOURS OVR THE FAR SERN PLAINS.
LONG TERM...
(TUESDAY THROUGH SUNDAY)
TUESDAY...TROUGH MOVES ACROSS THE NORTHERN ROCKIES WITH COLORADO
BEING ON THE SOUTHERN EDGE OF THE TROUGH. MAIN FORECAST CHALLENGE WILL
BE THE AMOUNT OF LOW LEVEL MOISTURE ON THE PLAINS. LATEST NAM AND
GFS HAVE DEW POINTS IN THE 50S TO LOWER 60S ON THE PLAINS TUESDAY
AFTERNOON. MODELS HAVE BEEN PLAGUED BY OVER-FORECASTING DEW POINTS
DURING THE ENTIRE SUMMER...AND HAVE DEW POINTS IN THE 40S TO LOWER
50S IN THE GRIDS. BELIEVE HIGHEST DEW POINTS WILL CLOSE TO THE NEW
MEXICO BORDER WHERE GRIDS HAVE ISOLATED TO SCATTERED POPS.
OTHERWISE...ONLY HAVE SILENT POPS FOR THE REMAINDER OF THE PLAINS.
IN THE MOUNTAINS...DRIER AIR WILL MOVE INTO THE REGION AND HAVE
POPS OVER THE SOUTHERN MOUNTAINS. A COLD FRONT WILL MOVE SOUTHWARD
ACROSS THE PLAINS TUESDAY NIGHT. WITH SOME LOW LEVEL MOISTURE
REMAINING OVER THE SOUTHEAST PORTION OF THE PLAINS...A STORM OR TWO
COULD DEVELOP ALONG THE FRONT...AND MAINTAINED ISOLATED POPS
OVERNIGHT OVER PORTIONS OF THE PLAINS.
WEDNESDAY...COLD FRONT WILL MOVE SOUTH OF THE STATE BY THE
AFTERNOON...WITH EASTERLY FLOW POOLING LOW LEVEL MOISTURE MOSTLY
OVER NORTHERN NEW MEXICO. SOME OF THE GUIDANCE HAS ENOUGH MOISTURE
REMAINING OVER SOUTHERN COLORADO FOR A FEW AFTERNOON AND EARLY
EVENING STORMS. DECIDED TO MAINTAIN SOME ISOLATED POPS IN THIS
REGION...BUT HEAVIER PRECIPITATION WILL STAY TO THE SOUTH OF THE
STATE. TEMPERATURES ON THE PLAINS WILL COOL TO NEAR NORMAL BEHIND
THE FRONT.
THURSDAY...A WEAK DISTURBANCE WILL MOVE ACROSS THE REGION WITH
LOW LEVEL DRYING OVER THE INTERSTATE 25 CORRIDOR. GFS CONTINUES TO
BE MUCH TOO HIGH WITH SURFACE DEW POINTS NEAR THE KANSAS
BORDER...WITH DEW POINTS IN THE LOWER 60S AND CAPES AROUND 1500
J/KG. GRIDS HAVE DEW POINTS NEAR THE KANSAS BORDER IN THE MID TO
UPPER 40S...AND ONLY HAVE ISOLATED POPS NEAR THE KANSAS BORDER.
THE PASSING DISTURBANCE SHOULD HELP FIRE CONVECTION OVER THE
MOUNTAINS...FOR SOME AFTERNOON AND EARLY EVENING STORMS.
.FRIDAY THROUGH SUNDAY...A TROUGH MOVES SOUTHEAST OUT OF CANADA AND
INTO THE HIGH PLAINS FRIDAY AND FRIDAY NIGHT. A SHARP COLD FRONT
WILL MOVE SOUTHWARD ACROSS THE PLAINS ON FRIDAY. GFS HAS
WIDESPREAD PRECIPITATION OVER THE EASTERN PLAINS AND INTERSTATE 25
CORRIDOR BEHIND THE FRONT AS SYNOPTIC SCALE LIFT AHEAD OF THE
TROUGH PASSES OVER THE MOIST LOW LEVEL AIR MASS. GFS DEW POINTS ON
FRIDAY ARE IN THE UPPER 50S TO LOWER 60S ON THE PLAINS. ONCE
AGAIN...BELIEVE DEW POINTS ARE MUCH TOO HIGH. EC DEW POINTS ARE IN
THE 40S...WHICH IS MORE REASONABLE. HAVE GENERALLY ISOLATED POPS
ON THE PLAINS AND INTERSTATE 25 CORRIDOR ON FRIDAY TO ACCOUNT FOR
SOME SHOWERS. LOW LEVEL AIR MASS BEHIND THE FRONT WILL BE COOL AND
LACK OF LOW LEVEL MOISTURE WILL RESULT IN A GENERALLY STABLE AIR MASS.
COOL LOW LEVEL AIR MASS REMAINS ON THE PLAINS SATURDAY WITH THE
ATMOSPHERE REMAINING CAPPED. BY SUNDAY...THE COOL AIR MASS MOVE TO
THE EAST WITH WARMER TEMPERATURES. MOISTURE LOOKS TO BE LIMITED
WITH ONLY SILENT POPS. --PGW--
AVIATION...
VFR CONDITIONS ARE EXPECTED AT THE TAF SITES FOR THE NEXT 24 HOURS.
SOME SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP TODAY...BUT
MAY BE FAIRLY SPOTTY NR THE TAF SITES. KCOS WL PROBABLY HAVE THE
BEST CHANCE OF SEEING SOME SHOWERS OR THUNDERSTORMS IN THE VCNTY.
HOWEVER...CONFIDENCE IS TOO LOW AT THIS TIME TO INCLUDE ANY MENTION
OF TSRA IN THE TAFS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
34/34
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
316 PM EDT Mon Sep 3 2012
.NEAR TERM [Through Tonight]...
With the presence of the upper level trough digging into the
region, areas of convection may linger into the overnight hours
longer than is typical for this time of year. The highest rain
chance during the overnight hours is expected to be in southeast
Alabama and portions of southwest Georgia closest to the influence
of the upper level trough. In fact, the model consensus suggests
likely PoPs in that region for the overnight hours and the
official forecast follows suit. Our local 12z hi-res ARW run (12z
RAP initialized with 12z NAM boundary conditions) is somewhat
concerning and indicates that an area of training convection could
develop during the overnight hours across portions of southeast
Alabama and adjacent sections of southwest Georgia. The large
scale environment could support such an occurrence with
precipitable water values forecast around 2.25 inches and
relatively weak steering flow. This is something that we will need
to keep a close eye on through the evening hours. A mention of
heavy rain was added into the forecast for late tonight across
southeast Alabama and adjacent areas of southwest Georgia.
Hopefully our local 18z hi-res ARW run (18z RAP initialized with
12z GFS boundary conditions) will shed some additional light on
this potential scenario. Min temperatures in the low to mid 70s
are expected areawide.
&&
.SHORT TERM [Tuesday Through Wednesday Night]...
The unsettled weather pattern which begins tonight, will continue
right through Wednesday night. A weak trough (loosely associated
with the remnamts of Isaac) is forecast to slide south across the
region over the next several days, with a weak surface low
possibly developing over the northeastern Gulf by Wednesday. With
copious amounts of moisture available (PWAT 2-2.5 inches) along
with modest upper forcing, expect solid coverage of convection
each day. The guidance is in good agreement in showing the
development of multiple convective complexes over the the next 60
hours. However, the exact timing, intensity, and location of these
episodes remains highly uncertain. Given the generally weak flow
aloft, severe weather is not the primary threat. However, there
may be a risk for localized flooding given the tropical nature of
the airmass. Some of the CAMS guidance is showing isolated rainfall
totals of 5-10 inches over the next 48 to 60 hours. Will continue
to monitor the evolution of this system, and a Flash Flood Watch
may need to be considered later if the convective trends
indicated by the hi-res guidance bear out.
Have bumped up PoPs through Wednesday night from previous
forecast, with likely PoPs for much of the area Tuesday and
Wednesday afternoons. Kept southeastern Big Bend a bit drier since
it will be closer to the subsident region on the west side of a
TUTT low over central/south Florida.
&&
.LONG TERM [Thursday through next Monday]...
Rain chances will continue each day with possibly the best chance
late next weekend as models show a very deep trough over the
eastern CONUS with an upper low closing off over the Ohio Valley.
This will send a strong cold front into the southeastern U.S. over
the weekend with a frontal passage possibly by the end of the
forecast period. Would like to see more run to run consistency
before increasing PoPs higher than chance and dropping temps and
dew points too low for the start of next week.
&&
.AVIATION [Beginning 18Z Monday]...
As an upper level trough affects the region, areas of convection
may linger into the overnight hours with the highest chance around
KDHN and KABY. Some MVFR to IFR cigs may also affect the terminals
towards dawn on Tuesday.
&&
.MARINE...
Relatively light southwesterly flow will continue through Tuesday
morning. However, by Tuesday afternoon and evening, the gradient
is forecast to tighten as weak low pressure drops south towards
the Gulf Coast. Exercise caution conditions are possible by
Wednesday morning over the western waters, speading eastward by
Wednesday afternoon. A period of advisory conditions is not out of
the question at some point on Wednesday or Thursday. Winds and
seas should diminish by late in the week as the trough of low
pressure moves east into the Atlantic.
&&
.FIRE WEATHER...
Relative humidity values will remain safely away from critical
levels for the next several days. Thus, no fire weather hazards
are currently anticipated.
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Van Dyke
SHORT TERM...Camp
LONG TERM...Barry
AVIATION...Van Dyke
MARINE...Camp
FIRE WEATHER...Van Dyke
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1249 PM CDT MON SEP 3 2012
.DISCUSSION...
ISSUED 1039 AM CDT MON SEP 3 2012
15Z/10 AM SURFACE CHART SHOWS 1009MB LOW CENTERED NEAR KEVV...WITH
CLOUD SHIELD EXTENDING ACROSS MUCH OF CENTRAL AND SOUTHEAST ILLINOIS.
FURTHER WEST...ENOUGH SUBSIDENCE IS OCCURRING ON THE BACK SIDE OF
THE SYSTEM TO ALLOW SKIES TO BECOME PARTLY TO MOSTLY SUNNY ALONG
AND WEST OF I-55. WITH ONLY VERY SLOW EASTWARD MOVEMENT...THINK
CLOUDS WILL PERSIST ACROSS THE E/SE KILX CWA THROUGH THE AFTERNOON.
12Z HRRR SUGGESTS A FEW SHOWERS MAY DEVELOP ACROSS THIS AREA AS
WELL...HOWEVER AREAL COVERAGE WILL BE MINIMAL. HAVE UPDATED
FORECAST TO REMOVE MENTION OF THUNDER...OPTING INSTEAD TO GO WITH
ISOLATED TO SCATTERED LIGHT SHOWERS ALONG AND EAST OF I-57. HIGH
TEMP FORECAST APPEARS TO BE ON TRACK...WITH COOLEST READINGS IN
THE LOWER TO MIDDLE 80S ACROSS THE CLOUD-COVERED EAST/SOUTHEAST
AND UPPER 80S FURTHER WEST. ZONE UPDATE HAS ALREADY BEEN ISSUED.
BARNES
&&
.AVIATION...
ISSUED 1249 PM CDT MON SEP 3 2012
CLOUD SHIELD ASSOCIATED WITH DEPARTING LOW PRESSURE HAS NOW SHIFTED
SOUTHEAST OF THE TERMINALS...HOWEVER ENOUGH LOW-LEVEL MOISTURE
REMAINS TO SUPPORT SCT-BKN MVFR CEILINGS THROUGH 20/21Z. AFTER
THAT...MOSTLY CLEAR SKIES WILL BE NOTED THIS EVENING BEFORE A WEAK
UPPER-LEVEL DISTURBANCE BEGINS TO SPREAD MID/HIGH CLOUDS BACK INTO
THE AREA OVERNIGHT INTO TUESDAY MORNING. 12Z NAM/GFS BOTH SUGGEST
SCT SHOWERS WITH THIS SYSTEM...HOWEVER CONFIDENCE CONCERNING EXACT
AREAL COVERAGE AND TIMING IS LOW...SO WILL ONLY FEATURE A PERIOD
OF VCSH AT ALL SITES AFTER 08/09Z. FORECAST SOUNDINGS ALSO INDICATE
THE POTENTIAL FOR AREAS OF FOG TONIGHT...HOWEVER INCREASING HIGH
CLOUDS MAY MITIGATE THIS THREAT. AT THIS POINT...HAVE INCLUDED
3-4SM VISBYS ACROSS THE BOARD...BUT THESE MAY NEED TO BE LOWERED
FURTHER IF CLOUD COVER DOES NOT MATERIALIZE AS CURRENTLY FORECAST.
BARNES
&&
.PREV DISCUSSION...
ISSUED 330 AM CDT MON SEP 3 2012
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
1008 MB LOW PRESSURE (REMNANTS OF ISAAC) WAS OVER FAR SE IL
BETWEEN LAWRENCEVILLE AND EVANSVILLE AND CONTINUED TO BRING
LOW CLOUDS TO AREAS FROM I-55 SE EARLY THIS MORNING WHILE NEARLY
CLEAR SKIES OVER THE IL RIVER VALLEY WITH A LIGHT FOG SO FAR.
GALESBURG VSBY WAS DOWN TO 2 MILES. HUMID AIRMASS LINGERS OVER
CENTRAL/SE IL WITH DEWPOINTS STILL IN THE LOWER 70S...EXCEPT 65F
AT GALESBURG. RADAR MOSAIC SHOWS MOST LIGHT SHOWERS HAVE
TEMPORARILY ENDED OVER CENTRAL/SE IL EARLY THIS MORNING...THOUGH
COULD BE A FEW SPRINKLES/DRIZZLE AROUND IN THE LOW CLOUDS FROM I-55
SE.
MODELS CONTINUE SLOW DRIFT OF LOW PRESSURE FROM FAR SE IL INTO
WESTERN KY TODAY AND STILL CLOSE ENOUGH TO BRING A CHANCE OF
SHOWERS OVER EASTERN IL LATER THIS MORNING AND AFTERNOON AND
PERHAPS AN ISOLATED THUNDERSTORMS IN SE IL THIS AFTERNOON. MORE
LOW CLOUDS LINGER OVER EASTERN IL AS WELL AND KEEP TEMPS A BIT
COOLER THERE. HIGHS IN THE MID 80S TO UPPER 80S WITH WARMER
READINGS WEST WHERE MORE SUNSHINE EXPECTED. WILL MENTION PATCHY
FOG FROM I-55 WEST UNTIL MID MORNING.
SOME FOG WILL LIKELY DEVELOP AGAIN OVERNIGHT AS LOW CLOUDS
DECREASE AND LINGER LONGER ALONG THE INDIANA BORDER. A WEAK
DISTURBANCE AND WEAKENING FRONT MOVE INTO NORTHERN/CENTRAL IL TUE
AND TO BRING ISOLATED SHOWERS AND THUNDERSTORMS BACK INTO AREA.
SPC HAS MUCH OF CENTRAL/SE IL IN A SLIGHT RISK OF SEVERE STORMS
WED AFTERNOON/EARLY WED EVENING UNTIL SUNSET. THIS DUE TO A STRONG
UPPER LEVEL SHORT WAVE AND COLD FRONT MOVING SE THROUGH IL. VERY
WARM AND HUMID AHEAD OF THIS FRONT THROUGH WED AND THEN TURNING
COOLER AND LESS HUMID THEREAFTER.
LONG TERM...THURSDAY THROUGH SUNDAY
EXTENDED MODELS CONTINUE TO BE PROGRESSIVE WITH YET ANOTHER FAIRLY
STRONG UPPER LEVEL DISTURBANCE TRACKING ESE INTO THE REGION LATE
THIS WEEK AND RETURNING A GOOD CHANCE OF SHOWERS AND ISOLATED
THUNDERSTORMS OVERNIGHT THU NIGHT INTO SAT. MODELS ALSO CONTINUE
TO SHOW A STRONG UPPER LEVEL TROF AND POSSIBLE CUTOFF LOW TAKING
SHAPE OVER THE GREAT LAKES/OHIO VALLEY REGION THIS WEEKEND...BRINGING
BELOW NORMAL TEMPERATURES ALONG WITH DIURNALLY ENHANCED CHANCES OF
SHOWERS AND CLOUDS DURING THE AFTERNOON HOURS.
KH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
205 PM MDT MON SEP 3 2012
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 200 PM MDT MON SEP 3 2012
LATEST WV IMAGERY SHOWS A NARROW BAND OF SUBSIDENCE OVER EASTERN
COLORADO MOVING INTO THE TRI-STATE AREA BEHIND THE UPPER LEVEL
TROUGH THAT BROUGHT LIGHT RAINFALL TODAY. RUC ANALYSIS HAS A SECOND
SHORT WAVE TROUGH FOLLOWING THE SUBSIDENCE BEHIND THE INITIAL SHORT
WAVE. AT THE SURFACE THE COLD FRONT FROM YESTERDAY EXTENDS FROM
SOUTHWEST KANSAS NORTHEAST TO IOWA. ANY STORM ACTIVITY THAT DEVELOPS
ALONG THE FRONT SHOULD BE WELL SOUTH OF THE AREA. OTHERWISE A
SUBTLE SURFACE TROUGH WAS LOCATED BETWEEN WRAY AND SAINT
FRANCIS...WHICH MAY SERVE TO HELP FOCUS CONVECTION OVER THE
NORTHWEST LATE THIS AFTERNOON AND THIS EVENING.
EARLY THIS EVENING SURFACE CONVERGENCE WILL DEVELOP OVER THE
NORTHWEST PART OF THE AREA BELOW A 700-500MB SHORT WAVE TROUGH.
THE DEEP LIFTING WILL GIVE THE BEST SHOT FOR RAINFALL TO REACH THE
GROUND. MEANWHILE THERE MAY BE SOME LINGERING STORMS IN THE HILL
CITY TO MCCOOK AREA...AS THE 700-500MB SHORT WAVE TROUGH THAT
BROUGHT RAIN EARLIER TODAY DEPARTS THE AREA. AS THE NIGHT
PROGRESSES PRECIP. CHANCES SHIFT FROM THE NORTHWEST TO THE SOUTH
AS A ANOTHER SHORT WAVE TROUGH MOVES ACROSS THE AREA. WITH A DEEP
DRY LAYER IN PLACE...AM NOT TOO CONFIDENT ANYTHING WILL REACH THE
GROUND.
TUESDAY ANOTHER SHORT WAVE TROUGH WILL MOVE THROUGH THE AREA.
DURING THE LATE MORNING THROUGH THE AFTERNOON A PRE-FRONTAL TROUGH
WILL DEVELOP AT THE SURFACE BELOW THE SHORT WAVE TROUGH. LIFT ALONG
THE SURFACE AND MID LEVEL TROUGH INCREASE THROUGH THE DAY. WITH
STRONGER LIFT OCCURRING DURING THE AFTERNOON HAVE INCREASED PRECIP.
CHANCES ALONG AND EAST OF THE SURFACE TROUGH. THESE AREAS WILL BE MORE
LIKELY TO HAVE STRONG TO SEVERE THUNDERSTORMS DUE TO THE BETTER
INSTABILITY.
THE 0-6KM SHEAR WILL BE AROUND 30 TO 35 KTS FOR THE PERIOD...WHICH
WILL SUPPORT ORGANIZED STORM STRUCTURE WITH PROLONGED UPDRAFTS. AM
THINKING THE MAIN THREAT WITH THESE STORMS WILL BE STRONG TO SEVERE
WIND GUSTS DUE TO THE HIGH CLOUD BASES.
TEMPERATURES WILL BE SIMILAR TO LAST NIGHT AND TODAY...WITH LOWS IN
UPPER 50S TO LOW 60S AND HIGHS IN THE 90S.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 131 PM MDT MON SEP 3 2012
TUESDAY NIGHT-THURSDAY...WILL KEEP A SMALL CHANCE OF PRECIPITATION
IN THE FORECAST EARLY TUESDAY NIGHT BEFORE DRIER AIR WORKS INTO
THE AREA UNDER NORTHWEST FLOW ALOFT THROUGH EARLY THURSDAY
MORNING. NOT TERRIBLY EXCITED ABOUT PRECIPITATION CHANCES THURSDAY
AFTERNOON DESPITE MOISTURE AVAILABILITY AS DYNAMICS RATHER WEAK.
TRIMMED POPS DOWN JUST A BIT. HIGH TEMPERATURES WEDNESDAY IN THE
LOW TO MID 80S...WARMING INTO THE UPPER 80S TO LOW 90S THURSDAY.
LOWS IN THE 50S TO LOW 60S.
THURSDAY NIGHT-FRIDAY NIGHT...PRECIPITATION CHANCES WILL SLOWLY
INCREASE THROUGH FRIDAY AS AN UPPER TROUGH AND COLD FRONT
APPROACH THEN MOVE THROUGH THE AREA. PRECIP CHANCES DECREASE FROM
NORTH TO SOUTH FRIDAY NIGHT AS THE SYSTEM MOVES OUT OF THE AREA
AND STABLE HIGH PRESSURE MOVES IN. HIGH TEMPERATURES FRIDAY 75-80.
LOWS THURSDAY NIGHT IN THE LOW 60S COOLING INTO THE LOW TO MID
50S FRIDAY NIGHT BEHIND THE FRONT.
SATURDAY-MONDAY...DRY. HIGH TEMPERATURES SATURDAY IN THE MID TO
UPPER 70S...WARMING INTO THE MID 80S TO AROUND 90 BY MONDAY.
OVERNIGHT LOWS NEAR TO SLIGHTLY ABOVE NORMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1108 AM MDT MON SEP 3 2012
VFR CONDITIONS FORECAST FOR THE 18Z TAFS. AREAS OF SHOWERS AND
THUNDERSTORMS SOUTHWEST OF KGLD ARE EXPECTED TO DIMINISH BY MID
AFTERNOON. WILL MONITOR AND AMEND KGLD IF NEEDED. KMCK SHOULD BE
ON THE WEST SIDE OF ANY PRECIPITATION. OTHERWISE WINDS WILL BE
LIGHT THROUGH THE AFTERNOON...WITH MAYBE A FEW GUSTS UP TO 15KTS.
TONIGHT STORMS SHOULD REMAIN WEST OF THE TAF SITES OR DIMINISH
BEFORE MOVING OVER THEM. LATE TUESDAY MORNING STORM COVERAGE IS
TOO ISOLATED FOR THE SITES TO MENTION IN THE TAF AT THIS TIME.
&&
.FIRE WEATHER...
ISSUED AT 200 PM MDT MON SEP 3 2012
TUESDAY AFTERNOON AREAS NORTH OF A KIT CARSON TO MCCOOK LINE WILL
HAVE RELATIVE HUMIDITIES DROP TO AROUND 15 PERCENT DURING THE
AFTERNOON. IN ADDITION WIND GUSTS AROUND 20 MPH CAN BE EXPECTED.
WHILE THIS IS BELOW ISSUANCE CRITERIA...CARE SHOULD BE TAKEN FOR
ANY OUTDOOR BURNING.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JTL
LONG TERM...99
AVIATION...JTL
FIRE WEATHER...JTL
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
346 PM EDT MON SEP 3 2012
.SYNOPSIS...
THE REMNANT LOW OF ISAAC WILL SLOWLY MOVE ACROSS THE UPPER OHIO
VALLEY THROUGH TUESDAY NIGHT, BRINGING THUNDERSTORMS AND HEAVY RAIN
TO THE AREA. THE SYSTEM WILL MOVE EAST OF THE AREA TUESDAY NIGHT
INTO EARLY WEDNESDAY, WITH A BREAK FROM SHOWERS AS HIGH PRESSURE
BUILDS IN FOR WEDNESDAY. A COLD FRONT WILL CROSS THE AREA ON
THURSDAY, RETURNING THE CHANCE FOR SHOWERS AND THUNDERSTORMS.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES THE REMNANT 500MB
CLOSED LOW OF TC ISAAC CENTERED IN SOUTHWESTERN OHIO. THE UPPER
OHIO VALLEY IS IN A MOIST LOW-LEVEL ENVIRONMENT, WITH DEW POINTS
IN THE LOW 70S ACROSS MOST OF THE AREA. WITH THE FORCING PROVIDED
FROM ISAAC AND MODERATE INSTABILITY, CONVECTION IS BEGINNING TO
INITIATE ACROSS CENTRAL WV AND SLIDE NORTHEASTWARD TOWARD THE
AREA.
THIS EVENING...THE REMNANT LOW OF ISAAC WILL SLOWLY CROSS OHIO,
WITH A SOUTHERLY FLOW AHEAD OF THIS FEATURE CONTINUING TO ADVECT DEEP
LAYER TROPICAL MOISTURE INTO EASTERN OHIO. THIS WILL ALLOW FOR
ANOTHER DAY OF SHOWERS AND THUNDERSTORMS, WITH PRECIP INCREASING
IN COVERAGE BY LATE AFTERNOON AND MOST LIKELY FOR LOCATIONS SOUTH
AND WEST OF PITTSBURGH. THIS IS SUPPORTED BY THE HRRR, WHICH
INDICATES CONVECTION IN CENTRAL WV STRENGTHENING AND BRINGING
HEAVY RAIN WITH THUNDERSTORMS TO NORTH-CENTRAL WV, EASTERN OHIO,
AND EXTREME SOUTHWEST PA.
RAINFALL, REGARDLESS OF ITS CONVECTIVE/TROPICAL NATURE, WILL BE
QUITE EFFICIENT TODAY, WITH THE RAP INDICATING PRECIPITABLE WATER
INCREASING TO 2 INCHES IN MOST AREAS SOUTH OF THE I-80 AND EVEN TO
2.2 INCHES IN PORTIONS OF EASTERN OHIO. WITH VERY WEAK LOW-LEVEL
WINDS TODAY, SHOWERS AND STORMS WILL BE SLOW MOVING. IN ADDITION,
WITH PREVIOUS RAINFALL SATURATING THE GROUND IN NORTH-CENTRAL WV
AND SOUTH OF I-70 IN EASTERN OHIO, 1-HR FFG IS 1 TO 1.5 INCHES IN
SOME BASINS. WITH THIS IN MIND, FLASH FLOODING IS NOT OUT OF THE
QUESTION AND REMAINS IN THE HWO. GENERALLY ANTICIPATE AROUND A
HALF INCH OF PRECIP TODAY, ALTHOUGH LOCALIZED AREAS COULD SEE TO 2
TO 3 INCHES.
TONIGHT...CONVECTION WILL BE ONGOING EARLY WITH THE MAJORITY OF THE
FORECAST AREA TRANSITIONING TO MORE TROPICAL BY DAWN TUESDAY. THE
CHANCE OF RAIN CANNOT BE RULED OUT OVERNIGHT AS THE REMNANTS OF
ISAAC CONTINUE TO MOVE ACROSS THE AREA. QPF AMOUNTS ARE AROUND A
QUARTER OF AN INCH, ALTHOUGH LOCALIZED HIGHER AMOUNTS WILL BE
POSSIBLE. A WARM AND MUGGY NIGHT CAN BE EXPECTED WITH LOWS A FEW
DEGREES ABOVE MAV/MET GUIDANCE, NEAR 70 ACROSS MOST OF THE AREA.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
THERE IS REASONABLE ECWMF/GFS/NAM AGREEMENT THAT THE BROAD REMNANT
SURFACE LOW OF ISAAC WILL FINALLY MAKE ITS WAY INTO THE FORECAST
AREA ON TUESDAY. THE LOW IS PROGGED TO BE INTO WESTERN PA BY 00Z
ON WEDNESDAY. SYNOPTIC FORCING AND ABUNDANT TROPICAL MOISTURE WITH
THIS FEATURE WILL ALLOW FOR ANOTHER DAY OF SHOWERS WITH HEAVY
RAIN. THERE IS SOME UNCERTAINTY WITH THUNDERSTORM COVERAGE IN A
TROPICAL AIR MASS, AS CLOUDS WILL BE A LIMITING FACTOR FOR
INSTABILITY. THUS, JUST WENT LIKELY POPS AND CHC THUNDER. QPF IS
ONLY AROUND A HALF OF AN INCH ACROSS THE AREA. HOWEVER, WITH PWAT
VALUES ABOVE 2 INCHES AND WEAK WINDS ALOFT, SLOW- MOVING
THUNDERSTORMS WILL AGAIN ALLOW FOR A LOCALIZED FLASH FLOODING
THREAT WHICH IS MENTIONED IN THE HWO.
ISAAC WILL FINALLY PULL EAST OF THE AREA TUESDAY NIGHT, WITH A DRY
FORECAST ON WEDNESDAY EVERYWHERE EXCEPT THE EASTERN RIDGES. THERE,
MOISTURE MAY LINGER ON THE BACK EDGE OF THIS SYSTEM LONG ENOUGH TO
WARRANT CHC POPS. THE DRY FORECAST CONTINUES UNTIL EARLY LATE
WEDNESDAY NIGHT WHEN A COLD FRONT BEGINS TO APPROACH FROM THE
NORTHWEST. THE FRONT WILL CROSS THE AREA ON THURSDAY, RETURNING
THE CHANCE OF SHOWERS AND THUNDERSTORMS. AT THIS TIME, A SEVERE
THREAT ON THURSDAY APPEARS TO BE LIMITED DUE WITH WEAK SHEAR WITH
THE SYSTEM.
FOR TEMPERATURES, THE LOWEST CONFIDENCE IS ON TUESDAY WITH CLOUD
COVERAGE AND SHOWERS. FORECAST TAKES THE NAM INTO
CONSIDERATION, WITH COOLER TEMPS CLOSER TO THE LOW CENTERED ACROSS
THE SOUTH. TEMP ADVECTION WILL BE LACKING BEHIND ISAAC, WITH HIGH TEMPS
CONTINUING TO BE AROUND 5 DEGREES ABOVE NORMAL ON WEDNESDAY AND
THURSDAY (AHEAD OF THE FRONT). WITH TDS REMAINING IN THE MID TO
UPPER 60S THROUGH THE MID-WEEK, TEMPS EACH NIGHT WILL BE AROUND 10
DEGREES ABOVE NORMAL FOR LOWS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
HIGH PRESSURE THURSDAY NIGHT IN THE WAKE OF A COLD FRONT IS
FORECAST TO BRING DRY WEATHER INTO FRIDAY. A COLD FRONT PUSHING INTO
THE OHIO VALLEY SATURDAY WILL BRING AN INCREASING RISK OF SHOWERS
FOR SATURDAY INTO SUNDAY. THE FRONT WILL MOVE EAST OF THE DISTRICT
MONDAY BRINGING AN END TO THE SHOWERS.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
RECENT RADAR DATA SHOWS BAND OF MVFR SHOWERS WILL MOVE SLOWLY
NORTHWARD ACROSS THE UPPER OHIO VALLEY THROUGH THIS EVENING.
SOME ISOLATED THUNDERSTORMS ARE POSSIBLE...ESPECIALLY IN THE
SOUTH BUT THE RISK OF SHOWERS IS TOO SLIGHT TO INCLUDE AS TEMPOS
IN THE TAFS. SURFACE WINDS WILL BE MAINLY SOUTHEAST AT 5 TO 10 KNOTS.
EXPECT MVFR RESTRICTIONS AFTER 08Z DUE TO FOG DEVELOPMENT. FOG COULD
DEVELOP EARLIER IF RAINFALL COVERAGE IS GREATER THAN CURRENTLY
PROJECTED.
.OUTLOOK /TUESDAY THROUGH FRIDAY/...
RESTRICTIONS ARE LIKELY TUESDAY DUE TO MORE NUMEROUS SHOWERS
ASSOCIATED WITH A COLD FRONTAL PASSAGE. RESTRICTIONS WILL STILL
BE POSSIBLE TUESDAY NIGHT INTO THURSDAY DUE TO SCATTERED SHOWERS AND
LATE NIGHT FOG UNTIL A SECOND COLD FRONTAL PASSAGE THURSDAY.
ENSUING DRY CONDITIONS WILL PROMOTE PREVALENT VFR FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
210 PM EDT MON SEP 3 2012
.SYNOPSIS...
THE REMNANT LOW OF ISAAC WILL SLOWLY MOVE ACROSS THE UPPER OHIO
VALLEY THROUGH TUESDAY NIGHT, BRINGING THUNDERSTORMS AND HEAVY RAIN
TO THE AREA. THE SYSTEM WILL MOVE EAST OF THE AREA TUESDAY NIGHT
INTO EARLY WEDNESDAY, WITH A BREAK FROM SHOWERS AS HIGH PRESSURE
BUILDS IN FOR WEDNESDAY. A COLD FRONT WILL CROSS THE AREA ON
THURSDAY, RETURNING THE CHANCE FOR SHOWERS AND THUNDERSTORMS.
&&
.NEAR TERM /THROUGH TONIGHT/...
18Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO REDUCE
POPS EARLY THIS AFTERNOON. TEMPS HAVE ALSO BEEN INCREASED IN
LOCATIONS WHERE THERE HAVE BEEN BREAKS IN THE CLOUDS.
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES THE REMNANT 500MB CLOSED
LOW OF TC ISAAC CENTERED IN SOUTHWESTERN OHIO. THE UPPER OHIO
VALLEY IS IN A MOIST LOW-LEVEL ENVIRONMENT, WITH DEW POINTS IN THE
LOW 70S ACROSS MOST OF THE AREA. WITH THE FORCING PROVIDED FROM
ISAAC AND MODERATE INSTABILITY, CONVECTION IS BEGINNING TO
INITIATE ACROSS CENTRAL WV AND SLIDE NORTHEASTWARD TOWARD THE
AREA.
THIS AFTERNOON...THE REMNANT LOW OF ISAAC WILL SLOWLY CROSS OHIO,
WITH A SOUTHERLY FLOW AHEAD OF THIS FEATURE CONTINUING TO ADVECT DEEP
LAYER TROPICAL MOISTURE INTO EASTERN OHIO. THIS WILL ALLOW FOR
ANOTHER DAY OF SHOWERS AND THUNDERSTORMS, WITH PRECIP INCREASING
IN COVERAGE BY LATE AFTERNOON AND MOST LIKELY FOR LOCATIONS SOUTH
AND WEST OF PITTSBURGH. THIS IS SUPPORTED BY THE HRRR, WHICH
INDICATES CONVECTION IN CENTRAL WV STRENGTHENING AND BRINGING
HEAVY RAIN WITH THUNDERSTORMS TO NORTH-CENTRAL WV, EASTERN OHIO,
AND EXTREME SOUTHWEST PA. FOR TEMPS, DESPITE 850MB TEMPS WARMING
TO THE 17-18C RANGE WITH WARM AND MOIST AIR MASS, CLOUD COVERAGE
WILL BE A LIMITING FACTOR WITH HIGHS TODAY. TEMPS ARE CLOSE TO THE
GFS LAMP, WITH HIGHS RANGING IN THE LOW TO MID 80S ACROSS MUCH OF
THE AREA.
RAINFALL, REGARDLESS OF ITS CONVECTIVE/TROPICAL NATURE, WILL BE
QUITE EFFICIENT TODAY, WITH THE RAP INDICATING PRECIPITABLE WATER
INCREASING TO 2 INCHES IN MOST AREAS SOUTH OF THE I-80 AND EVEN TO
2.2 INCHES IN PORTIONS OF EASTERN OHIO. WITH VERY WEAK LOW-LEVEL
WINDS TODAY, SHOWERS AND STORMS WILL BE SLOW MOVING. IN ADDITION,
WITH PREVIOUS RAINFALL SATURATING THE GROUND IN NORTH-CENTRAL WV
AND SOUTH OF I-70 IN EASTERN OHIO, 1-HR FFG IS 1 TO 1.5 INCHES IN
SOME BASINS. WITH THIS IN MIND, FLASH FLOODING IS NOT OUT OF THE
QUESTION AND REMAINS IN THE HWO. WILL HAVE TO CONTINUE TO WATCH
RADAR AND MESOSCALE MODEL TRENDS, AS A FLASH FLOOD WATCH MAY BE
NEEDED. GENERALLY ANTICIPATE AROUND A HALF INCH OF PRECIP TODAY,
ALTHOUGH LOCALIZED AREAS COULD SEE TO 2 TO 3 INCHES.
TONIGHT...CONVECTION WILL BE ONGOING EARLY WITH THE MAJORITY OF THE
FORECAST AREA TRANSITIONING TO MORE TROPICAL BY DAWN TUESDAY. THE
CHANCE OF RAIN CANNOT BE RULED OUT OVERNIGHT AS THE REMNANTS OF
ISAAC CONTINUE TO MOVE ACROSS THE AREA. QPF AMOUNTS ARE AROUND A
QUARTER OF AN INCH, ALTHOUGH LOCALIZED HIGHER AMOUNTS WILL BE
POSSIBLE. A WARM AND MUGGY NIGHT CAN BE EXPECTED WITH LOWS A FEW
DEGREES ABOVE MAV/MET GUIDANCE, NEAR 70 ACROSS MOST OF THE AREA.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
SHOWER/STORM CHANCES WILL QUICKLY INCREASE TUESDAY MORNING, AS
THE ENTIRE SYSTEM BEGINS TO PICK UP SPEED AND MOVE TO THE EAST.
THE PUSH WILL COME FROM A SHORTWAVE TROUGH, WHICH WILL CROSS THE
GREAT LAKES TUESDAY MORNING AND MOVE INTO W PA DURING THE
AFTERNOON. THE ENERGY FROM THE NORTHERN TROUGH WILL WORK IN
CONJUNCTION WITH THE ENERGY AND MOISTURE FROM ISAAC`S REMNANTS TO
PROVIDE A WET TUESDAY FOR MUCH OF THE AREA. THE ATMOSPHERE WILL
REMAIN JUICY, SO HEAVY DOWNPOURS ARE A THREAT ON TUESDAY,
ESPECIALLY WITH STORMS THAT MAY DEVELOP.
THE SFC WAVE WILL MOVE THROUGH TUESDAY NIGHT DRAGGING BEHIND THE
SFC COLD FRONT. FRONT WILL STALL ACROSS THE SOUTH AND EAST LATE
TUESDAY NIGHT, WAITING FOR A PUSH FROM THE NEXT UL WAVE. WILL SHOW
A DECREASE IN POPS TUESDAY NIGHT, WHILE LEAVING RAIN CHANCES INTO
WED MORNING ACROSS THE SOUTH AND RIDGES.
WEDNESDAY`S SW TROUGH WILL FINALLY KICK THE ENTIRE SYSTEM OUT OF
THE UPPER OHIO VALLEY, WHICH WILL END THE RISK FOR PRECIPITATION AND
ALSO BRING A SLOW DECREASE IN CLOUD COVER.
SUNSHINE SHOULD MAKE A RETURN BE WED AFTERNOON.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
A SECONDARY...AND DECISIVE COLD FRONT IS PROJECTED ACROSS THE AREA BY
THURSDAY. BUILDING HIGH PRESSURE IN THE WAKE OF THE FRONT IS FORECAST
TO BRING DRY WEATHER TO CLOSE THE WEEK. ANOTHER FRONT...CURRENTLY
TIMED FOR AN EARLY SUNDAY APPROACH MAY BRING THE NEXT CHANCE FOR
SHOWERS.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
RECENT RADAR DATA SHOWS BAND OF MVFR SHOWERS WILL MOVE SLOWLY
NORTHWARD ACROSS THE UPPER OHIO VALLEY THROUGH THIS EVENING.
SOME ISOLATED THUNDERSTORMS ARE POSSIBLE...ESPECIALLY IN THE
SOUTH BUT THE RISK OF SHOWERS IS TOO SLIGHT TO INCLUDE AS TEMPOS
IN THE TAFS. SURFACE WINDS WILL BE MAINLY SOUTHEAST AT 5 TO 10 KNOTS.
EXPECT MVFR RESTRICTIONS AFTER 08Z DUE TO FOG DEVELOPMENT. FOG COULD
DEVELOP EARLIER IF RAINFALL COVERAGE IS GREATER THAN CURRENTLY
PROJECTED.
.OUTLOOK /TUESDAY THROUGH FRIDAY/...
RESTRICTIONS ARE LIKELY TUESDAY DUE TO MORE NUMEROUS SHOWERS
ASSOCIATED WITH A COLD FRONTAL PASSAGE. RESTRICTIONS WILL STILL
BE POSSIBLE TUESDAY NIGHT INTO THURSDAY DUE TO SCATTERED SHOWERS AND
LATE NIGHT FOG UNTIL A SECOND COLD FRONTAL PASSAGE THURSDAY.
ENSUING DRY CONDITIONS WILL PROMOTE PREVALENT VFR FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
530 PM EDT MON SEP 3 2012
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 517 PM EDT MON SEP 3 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW WSW FLOW OVER THE UPPER
GREAT LAKES BTWN UPPER RIDGE EXTENDING FROM THE PLAINS TO THE LWR
LAKES AND A DEEP...OCCLUDED LOW OVER NRN MANITOBA. NARROW MOISTURE
RIBBON HAS SHIFTED INTO THE UPPER LAKES IN ASSOCIATION WITH
DISSIPATING SFC TROF ORIGINALLY ASSOCIATED WITH DEEP SYSTEM IN NRN
MANITOBA. LEFT EXIT OF UPPER JET STREAK AIDED EARLY MORNING
CONVECTION OVER NW UPPER MI/LAKE SUPERIOR. BASED ON LATEST RUC
ANALYSIS...IT APPEARS CONVECTION THAT HAS BEEN DEVELOPING MAY BE
GETTING SOME SUPPORT FROM THE RIGHT ENTRANCE OF JET STREAK NOW.
ONGOING CONVECTION OVER ROUGHLY THE SE HALF OF THE FCST AREA WILL
CONTINUE SETTLE SE INTO THE EVENING HRS. WITH MUCAPE ON THE ORDER
OF 1000-2000J/KG AND DEEP LAYER SHEAR AROUND 40KT...ORGANIZED STORMS
WILL CONTINUE ALONG WITH THE POTENTIAL OF SVR FOR THE NEXT SEVERAL
HRS. SHRA/TSRA SHOULD BE OUT OF THE SE/SCNTRL FCST AREA MID TO LATE
EVENING. HEALTHY DRYING ALOFT (NOTE UPSTREAM 12Z KINL SOUNDING) WILL
THEN OCCUR THRU THE NIGHT...ENDING ANY THREAT OF ADDITIONAL PCPN.
CONSIDERING DRYNESS OF INCOMING AIR MASS AND LIGHT/CALM WIND
UNDER BUBBLE SFC HI PRES BUILDING INTO THE AREA...FAVORED
THE LOWER SIDE OF AVBL GUIDANCE FOR MIN TEMPS. VIGOROUS DRYING
ALOFT/LIGHT WINDS FAVOR FOG DEVELOPMENT...ESPECIALLY SINCE THERE HAS
BEEN RAINFALL TODAY. THUS...MAINTAINED MENTION OF AREAS OF FOG OVER
MUCH OF THE INTERIOR.
ON TUE...ATTENTION TURNS TO A COUPLE OF SHORTWAVES EXTENDING FROM
ND INTO MT. ONE OR BOTH OF THESE WAVES WILL REACH THE UPPER LAKES
TUE AND WILL LIKELY PROVIDE SUFFICIENT FORCING FOR ISOLD/SCT
CONVECTION. GIVEN THAT CONVECTION IS CURRENTLY BEING OBSERVED OVER
THE ERN DAKOTAS AHEAD OF THE FIRST WAVE...BUMPED POPS UP INTO THE
CHC CATEGORY OVER ROUGHLY THE W HALF OF THE FCST AREA TUE. ALTHOUGH
NAM/GFS MLCAPES ARE IN THE 1500-2500J/KG RANGE...DEEP LAYER SHEAR IS
UNDER 30KT WHICH WILL WORK TO LIMIT MORE WIDESPREAD SVR POTENTIAL.
NONETHELESS...IF STORMS DO DEVELOP...MAY SEE SOME ISOLD/PULSE TYPE
SVR STORMS TUE AFTN.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 517 PM EDT MON SEP 3 2012
BASIC OUTLOOK OF THE LONG TERM NOT TOO DIFFERENT FROM YESTERDAY. WV
LOOP AND 12Z RAOBS INDICATE PAIR OF UPPER LOWS IN CANADA FROM
NORTHERN MANITOBA INTO NORTHERN BRITISH COLUMBIA. MANITOBA LOW STAYS
FAIRLY STATIONARY THROUGH WEDNESDAY WHILE THE BRITISH COLUMBIA LOW
DIGS TO ITS SOUTH AND EVENTUALLY SOUTHEAST INTO NORTHERN ONTARIO. AS
THIS OCCURS...STRONG SFC-H85 COLD FRONT MARCHES ACROSS UPPER GREAT
LAKES WEDNESDAY AFTERNOON AND EVENING. DYNAMICS PROVIDED BY 12-HR
H5 HEIGHT FALLS TO 60M AND A COUPLED JET STRUCTURE COMBINE WITH
SFC-H85 FRONT AND SURGE OF H85 MOISTURE TRANSPORT TO GENERATE SHRA
ALONG AND AHEAD OF THE FRONT. DEPENDING ON TIMING OF FRONT AND
HEATING AHEAD OF FRONT...TSRA COULD BE STRONG GIVEN 0-6KM CAPES UP
TO 1500 J/KG AND AS H85 JET INCREASES OVER CWA AND BECOMES PARALLEL
TO THE H5 FLOW. SETUP IS FAVORABLE FOR DYNAMICALLY DRIVEN BOW-ECHO
SOMEWHERE OVER THE AREA AS THERE IS A DRY H7-H5 LAYER PUNCHING INTO
THE AREA FROM THE WEST WITH DWPNT DEPRESSIONS OVR 20C BY LATER AFTN.
BEST CHANCE FOR SEVERE PROBABLY ENDS UP SOUTH AND EAST OF CWA WHERE
GREATEST MLCAPES ARE FORECAST IN THE AFTN. AT THE LEAST...LIKELY
POPS ARE CERTAINLY WARRANTED AS THE SFC-H85 FRONT WORKS ACROSS THE
CWA.
ONCE FRONT PLOWS THROUGH MAY SEE HIGHER WIND GUSTS WEDNESDAY NIGHT
INTO THURSDAY AS SFC LOW WRAPS UP BTWN LAKE SUPERIOR AND HUDSON BAY.
GFS/ECMWF H85 WINDS NOT THAT STRONG...MAYBE UP TO 30 KTS...SO DOES
NOT APPEAR THAT WINDS WILL BECOME TOO STRONG. IF THE SFC LOW ENDS UP
DEEPENING CLOSER TO LK SUPERIOR...COULD SEE NORTHWESTERLY WIND GUSTS
ALONG LK SUPERIOR 40-45 MPH. AT THIS POINT...WX ON THURSDAY SHOULD
END UP QUIET AS UPR MICHIGAN IS BTWN THE STRONG SHORTWAVE TROUGH
THAT MOVES THROUGH MID WEEK AND RE-INFORCING TROUGH THAT IS FORECAST
TO ROTATE THROUGH ON FRIDAY. FORECAST SOUNDINGS FROM GFS AND OUTPUT
FROM GEM-NHEM INDICATE SOME POTENTIAL FOR LIGHT SHRA OVER THE
EASTERN CWA IN WEAK AREA OF LOW-LEVEL CONVERGENCE. SEEMS GREATER
CHANCE OF SHRA ARRIVES ON FRIDAY WITH THE INCOMING TROUGH AND
INDICATION OF SHORTWAVE RIDING THROUGH IN WEST/NORTHWEST FLOW
ALOFT. THIS FORCING ALONG WITH INCREASING OVER-WATER INSTABILITY
WITH LAKE EFFECT CAPES PUSHING AOA 500J/KG SUGGESTS HYBRID LATE
SUMMER AND EARLY FALL TYPE SHRA AND MAYBE EVEN MENTION OF TSRA
GIVEN LAKE INDUCED EQL OVER 20KFT WHICH PUSHES CONVECTIVE DEPTH
BLO 0C.
GIVEN LAKE-H85 DELTA T AOA 15C...DEEP LAKE INDUCED CLOUD DEPTH...AND
WINDS WITHIN THE MIXED LAYER STAYING BLO 25 KTS...PARAMETERS STILL
LINE UP FOR WATERSPOUT POTENTIAL ON FRIDAY...ESPECIALLY IF SUBTLE
LOW-LEVEL TROUGH THAT IS SHOWING UP IN MODELS OVER EASTERN LK
SUPERIOR/EASTERN CWA DOES INDEED VERIFY. TOUGH TO INCLUDE MENTION OF
WATERSPOUTS THIS FAR OUT IN THE FORECAST BUT WILL BE INTERESTING TO
SEE OUTPUT IN THE NEXT COUPLE DAYS FROM THE NEW EXPERIMENTAL GREAT
LAKES WATERSPOUT FORECAST BASED ON THE SZILAGYI WATERSPOUT INDEX
/SWI/ THAT COMES OUT OF THE INTERNATIONAL CENTRE FOR WATERSPOUT
RESEARCH /ICWR/. IN ADDITION TO WATERSPOUTS...WILL ALSO LIKELY HAVE
INCREASED RISK OF RIP CURRENTS ALONG LK SUPERIOR BEACHES...MAINLY IN
ALGER COUNTY WITH THE EXPECTED NORTHWEST WINDS.
UPPER TROUGH SLOWLY MOVES EAST THROUGH NEXT WEEKEND. THIS PLACES
UPPER LAKES WITHIN ZONE OF SHARP CONFLUENCE AND ASSOCIATED SFC
RIDGING. ECMWF HAS DEFINITELY TRENDED FARTHER EAST WITH TROUGH AND
KEEPS QPF OUT OF UPR MICHIGAN FOR THE WEEKEND. GFS IS SLIGHTLY
FARTHER WEST WITH THE TROUGH AND WOULD KEEP THREAT OF SHRA OVER
EASTERN CWA ON SATURDAY. BASED ON AMPLIFIED PATTERN CANNOT RULE THIS
IDEA OUT AND WILL AT THE LEAST KEEP CONSENSUS SLIGHT CHANCE POPS AND
BUMP UP SKY COVER. SUNDAY INTO MONDAY IS TOUGH TO FIGURE OUT AS
ECMWF CONTINUES TO INDICATE STRONGER SHORTWAVE WITHIN BASE OF TROUGH
LIFTING NORTH AND AFFECTING THE EASTERN PORTIONS OF CWA WITH SOME
SHRA WHILE THE GFS KEEPS ALL THIS TOO FAR TO THE EAST TO AFFECT THE
AREA. NO REAL CONSISTENT SIGNAL FOR EITHER SOLUTION SO HAVE TO KEEP
CONSENSUS POPS AT THIS TIME.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 139 PM EDT MON SEP 3 2012
WITH WEAK SFC TROF MOVING ACROSS UPPER MI...KSAW MAY BE IMPACTED BY
BRIEF SHRA/TSRA AND MVFR CONDITIONS OVER THE NEXT COUPLE OF HRS.
TROF IS ALREADY PAST KIWD/KCMX...SO THE AFTN WILL HAVE VFR CONDITIONS
AND NO PCPN AT THOSE 2 SITES. WITH SFC WINDS DIMINISHING TO
LIGHT/CALM UNDER UPPER LEVEL DRYING...FOG IS LIKELY TO FORM TONIGHT
WITH IFR...POSSIBLE LIFR...CONDITIONS. FOG WILL DISSIPATE WITHIN A
COUPLE OF HRS AFTER SUNRISE TUE. NEXT DISTURBANCE APPROACHING THE AREA
MAY TRIGGER ISOLD/SCT CONVECTION TUE...BUT MOST LIKELY NOT UNTIL BEYOND
THIS FCST PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 429 AM EDT MON SEP 3 2012
EXPECT S WINDS UP TO 20 KTS IN ADVANCE OF AN APPROACHING COLD FRONT
TO DIMINISH THIS EVENING AS THE FRONT TENDS TO WEAKEN. LIGHT WINDS WILL
THEN PREVAIL THRU TONIGHT AS A WEAK HI PRES SYSTEM MOVES INTO THE
UPPER GREAT LAKES. A SERIES OF LOW PRESSURE SYSTEMS AND COLD FRONTS
WILL MOVE NEAR LAKE SUPERIOR TUESDAY THROUGH SUNDAY...LEADING TO
PERIODS OF INCREASED WINDS. HOWEVER...AT THIS TIME WINDS ARE EXPECTED
TO REMAIN BELOW 25KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...ROLFSON
MARINE...KC/TITUS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
140 PM EDT MON SEP 3 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 429 AM EDT MON SEP 3 2012
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WSW FLOW ALF OVER
THE UPR GRT LKS BTWN UPR RDG EXTENDING FM THE PLAINS INTO LWR MI AND
DEEP...OCCLUDED LO OVER NRN SASKATCHEWAN THAT IS DRIFTING ONLY
SLOWLY EWD. THE REMNANTS OF HURRICANE ISAAC CONTINUE TO DRIFT EWD
THRU THE OH VALLEY S OF THE UPR RDG AXIS. WARM CONVEYOR BELT MSTR
RIBBON...IN ADVANCE OF COLD FNT MOVING THRU MN THAT IS ATTENDANT TO
SASKATCHEWAN OCCLUSION...HAS PUSHED INTO ERN MN/WRN UPR MI.
HOWEVER...CIRCULATION ARND ISAAC HAS LIMITED MSTR INFLOW INTO THIS
SYSTEM AS EVIDENCED BY VERY DRY AIRMASS SHOWN ON THE 00Z MPX RAOB
AND H85 DEWPT DEPRESSIONS NEAR 20C STRETCHING FM THAT SITE SWWD INTO
THE CENTRAL PLAINS. SINCE THIS DRY AIR IS FEEDING NEWD TOWARD NE
MN/UPR MI IN THE SSW SFC-H85 FLOW AHEAD OF COLD FNT...AT 06Z THERE
WAS NO PCPN FALLING S OF THE CNDN BORDER FM THIS CLD DESPITE STEEP
MID LVL LAPSE RATES AND MUCAPE 500-1000 J/KG AS SHOWN BY SPC
MESOANALYSIS. ISOLD -SHRA/A FEW LTG STRIKES WERE EVIDENT IN ONTARIO
WHERE MSTR IS DEEPER PER 00Z YPL RAOB CLOSER TO SHARPER DEEP LYR
QVECTOR CNVGC ASSOCIATED WITH OCCLUSION TO THE W. HOWEVER...APRCH OF
70KT H3 JET MAX IN THE NRN PLAINS/SOME UPR DVGC HAS CAUSED MORE
SHRA/TS TO DVLP OVER WRN LK SUP CLOSER TO FCST ISSUANCE. BEHIND THE
COLD FNT IN THE NRN PLAINS...00Z ABERDEEN SDAKOTA AND BISMARCK RAOBS
SHOW A VERY DRY AIRMASS. LATEST WV IMAGERY SHOWS THIS DRIER AIR ALF
SPREADING EWD.
MAIN FCST CONCERNS IN THE SHORT TERM ARE SHRA/TS CHCS TODAY AS COLD
FNT/MSTR RIBBON PRESS TO THE E.
TODAY...COLD FNT IN MN IS PROGGED TO DRIFT INTO UPR MI AND DISSIPATE
AS THIS BNDRY OUTRUNS THE CLOSED LO IN SASKATCHEWAN THAT IS PROGGED
TO DRIFT ONLY SLOWLY INTO MANITOBA. PCPN CHCS WL BE HINDERED BY DRY
ADVECTION NOTED ABOVE AND EXIT OF DEEP LYR QVECTOR CNVGC TO THE N.
HOWEVER...BULK OF MODELS SHOWED THE INCRSG H4-2 UPR DVGC EARLY THIS
MRNG IN ADVANCE OF JET MAX MOVING ENEWD THRU THE NRN PLAINS...SO
WENT WITH SCT -SHRA/TSRA TO START OFF FCST PERIOD OVER THE W WITH
THE SOMEWHAT HIER POPS FARTHER TO THE N CLOSER TO DEEPER MSTR/
LINGERING DEEP LYR QVECTOR CNVGC. THIS UPR DVGC IS PROGGED TO EXIT
TO THE NE BY MID MRNG...SO EXPECT POPS TO DIMINISH FOR A TIME.
QUESTION THEN BECOMES WHETHER DAYTIME HEATING CAN INVIGORATE DIURNAL
CONVECTION IN ABSENCE OF APPRECIABLE DYNAMIC SUPPORT AND AGAINST
ONSLAUGHT OF INCOMING DRY AIR THAT IS PROGGED TO DROP KINX BLO 10
OVER THE W HALF BY 18Z FOLLOWING THE DISSIPATING COLD FROPA PER
FAVORED GFS THAT BEST MATCHES WV IMAGERY TRENDS OF VIGOROUS DRYING
ALF MOVING E FM THE NRN PLAINS. BEST SHOT FOR THIS CONVECTION
APPEARS TO BE OVER THE E AND SCNTRL...WHERE KINX IS PROGGED TO
REMAIN NEAR 30 THRU 18Z AND WHERE DVLPG LK BREEZES MIGHT ENHANCE
LLVL CNVGC. BUT EVEN IN THIS AREA...KINX IS FCST TO FALL BLO 20 BY
00Z EXCEPT FOR AREAS NEAR LK MI. AS FOR SVR THREAT...MODELS DEPICT
DEEP LYR SHEAR AS HI AS 30-35 KTS OVER THE SCNTRL AT 18Z. MODIFIED
GFS FCST SDNG FOR ESC AT 18Z FOR SFC T/TD 83/66 YIELDS SBCAPE NEAR
1400 J/KG DESPITE LESS IMPRESSIVE MID LVL LAPSE RATES FCST IN THAT
AREA. WITH VIGOROUS DRYING ALF...SFC-10K DELTA THETA-E IS PROGGED TO
INCRS TO A SGNFT 25-30C BY LATE IN THE DAY...INCRSG THE DCAPE IN THE
PRESENCE OF UNIDIRECTIONAL WLY FLOW ALF/THREAT FOR DAMAGING WINDS.
DESPITE MID LVL DRYING...FCST HI WBZ NEAR 13K FT WOULD PROBABLY
MINIMIZE THE POTENTIAL FOR LARGE HAIL. BUT MAIN CONCERN IS HOW
VIGOROUS MID LVL DRYING WL IMPACT SHRA/TS CHCS. IN FACT...THE
GREATER SHEAR MIGHT ACT TO ENTRAIN SO MUCH DRIER AIR INTO THE STORM
TOWERS AND LIMIT THE INTENSITY OF THE CONVECTION. WL CONTINUE TO
MENTION THE THREAT OF SOME STRONGER STORMS IN THE HWO. AS FOR HI
TEMPS...MIXING TO H85 ON GFS FCST SDNGS YIELDS HI TEMPS REACHING THE
MID/UPR 80S AWAY FM LK MODERATION...IN GOOD AGREEMENT WITH MAX TEMPS
OBSVD UPSTREAM ON SUN.
TNGT...WITH VIGOROUS UPR DRYING PER THE GFS THAT CAUSES H85-5 MEAN
RH TO FALL AS LO AS 20 PCT BY 06Z...ANY LINGERING SHRA/TS OVER THE
SE CWA IN THE EARLY EVNG WL END WITH LOSS OF DAYTIME HEATING IN THE
ABSENCE OF ANY DYNAMIC SUPPORT. CONSIDERING DRYNESS OF INCOMING
AIRMASS AND LGT WINDS UNDER BUBBLE HI PRES BLDG INTO THE AREA...
TENDED TOWARD THE LOWER GFS GUIDANCE FOR MIN TEMPS. VIGOROUS DRYING
ALF/LGT WINDS FAVOR FOG DEVELOPMENT...SO WENT WITH AREAS OF FOG OVER
MUCH OF THE INTERIOR.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 429 AM EDT MON SEP 3 2012
THE PERIOD STARTS 12Z TUE WITH A CLOSED UPPER LOW OVER NRN
MANITOBA...AND A SFC TROUGH/WEAK COLD FRONT W OF THE CWA. SHORTWAVE
ENERGY IS THEN COMBINED INTO THE SRN SIDE OF THE UPPER LOW THROUGH
WED...CAUSING THE SYSTEM TO MOVE FARTHER W TO FAR NW ONTARIO BY 00Z
THU. EXACTLY WHEN AND WHERE THE SHORTWAVE ENERGY MOVES WILL GREATLY
IMPACT THE FORECAST FOR TUE AND TUE NIGHT...SO CONFIDENCE IS LOWER
FOR THIS TIME PERIOD. WE COULD STAY DRY ACROSS MOST OF THE CWA ON
TUE...AS THE 12Z/02 ECMWF SHOWS DUE TO THE SHORTWAVE STAYING FATHER
TO THE N THAN IN OTHER MODELS. ALSO...MODEL FORECAST SOUNDING SHOW
DIFFERENCES BETWEEN LOW LEVEL MOISTURE WHICH WILL RESULT IN
INCREASED TO DECREASED CIN. WILL NOT CHANGE THE PREVIOUS POP
FORECAST WITH SLIGHT CHANCE TO LOW CHANCE POPS MAINLY IN THE
AFTERNOON. IF SHOWERS AND THUNDERSTORMS DO DEVELOP...THERE MAY BE
SOME STRONG TUE AFTERNOON AS CAPE INCREASES TO AOA 1500 J/KG BUT
0-6 KM SHEAR REMAINS BELOW 25 KTS.
A STRONGER COLD FRONT/SFC TROUGH SHOULD MOVE THROUGH ON WED...BUT
TIMING AND INTENSITY REMAINS IN QUESTION AS MODELS DO NOT HANDLE THE
SITUATION WELL. THIS IS AGAIN RELATED TO THE PATH THE SHORTWAVE
TAKES. THE DIFFERENCES BETWEEN TIMING PLAY OUT THE MOST WITH
THUNDERSTORM INTENSITY ON WED...WITH THE SLOWER GUIDANCE BRING THE
FRONT THROUGH AROUND PEAK HEATING WHICH WOULD RESULT IN MORE
INSTABILITY. THE FASTER MODELS MOVE THINGS THROUGH EARLIER AND
THEREFORE...INSTABILITY RESULTING FROM DAYTIME HEATING IS MAXIMIZED
AOA 1500 J/KG. 0-6KM SHEAR SHOULD BE ON THE ORDER OF 40-50
KTS...WITH 0-1KM SHEAR OF AROUND 15 KTS. FLOW WILL BE MOSTLY
UNIDIRECTIONAL...SO THE SHEAR IS MOSTLY SPEED SHEAR. MORE ALONG THE
LINES OF WORST CASE SCENARIO REGARDING TIMING/INSTABILITY...SOME
STORMS COULD BE SEVERE IN THE AFTERNOON WITH WIND GUSTS BEING THE
PRIMARY HAZARD /DUE PARTY TO DRY MID LEVELS/. THERE WOULD BE A LARGE
HAIL THREAT...BUT THAT IS MORE CONDITIONAL. REGARDLESS OF TIMING OF
THE FRONT...PRECIP DOES LOOK MORE CERTAIN THAN ANY OTHER DAY IN THE
EXTENDED...BUT THAT SHORTWAVE WILL MAKE THINGS TRICKY. INCREASED
POPS TO LIKELY...ESPECIALLY CENTRAL AND E...AND HIGH CHANCE POPS
OVER THE FAR W.
THE UPPER LOW WILL CONTINUE TO MOVE EVERY SO SLOWLY ESE...AND WILL
BE CLOSEST TO THE CWA THU NIGHT. EXPECT 850MB TEMPS AROUND 4-6C THU
INTO FRI..WHICH MAY LEAD TO SOME LAKE EFFECT RAIN DOWNWIND OF N/NW
WINDS. MODEL AGREEMENT AND CONTINUITY DEGRADE SIGNIFICANTLY FRIDAY
THROUGH SUNDAY...SO CONFIDENCE IS SIGNIFICANTLY LOWER FOR NEXT
WEEKEND. IT DOES APPEAR...HOWEVER...THAT A RETURN TO OR EVEN BELOW
NEAR NORMAL TEMPERATURES IS IN STORE FOR THU THROUGH SUN. USED
CONSENSUS OF MODEL GUIDANCE GIVEN UNCERTAINTY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 139 PM EDT MON SEP 3 2012
WITH WEAK SFC TROF MOVING ACROSS UPPER MI...KSAW MAY BE IMPACTED BY
BRIEF SHRA/TSRA AND MVFR CONDITIONS OVER THE NEXT COUPLE OF HRS.
TROF IS ALREADY PAST KIWD/KCMX...SO THE AFTN WILL HAVE VFR CONDITIONS
AND NO PCPN AT THOSE 2 SITES. WITH SFC WINDS DIMINISHING TO
LIGHT/CALM UNDER UPPER LEVEL DRYING...FOG IS LIKELY TO FORM TONIGHT
WITH IFR...POSSIBLE LIFR...CONDITIONS. FOG WILL DISSIPATE WITHIN A
COUPLE OF HRS AFTER SUNRISE TUE. NEXT DISTURBANCE APPROACHING THE AREA
MAY TRIGGER ISOLD/SCT CONVECTION TUE...BUT MOST LIKELY NOT UNTIL BEYOND
THIS FCST PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 429 AM EDT MON SEP 3 2012
EXPECT S WINDS UP TO 20 KTS IN ADVANCE OF AN APPROACHING COLD FRONT
TO DIMINISH TODAY AS THE FRONT TENDS TO WEAKEN. LIGHT WINDS WILL
THEN PREVAIL THRU TONIGHT AS A WEAK HI PRES SYSTEM MOVES INTO THE
UPPER GREAT LAKES. A SERIES OF LOW PRESSURE SYSTEMS AND COLD FRONTS
WILL MOVE NEAR LAKE SUPERIOR TUESDAY THROUGH SUNDAY...LEADING TO
PERIODS OF INCREASED WINDS. HOWEVER...AT THIS TIME WINDS ARE EXPECTED
TO REMAIN BELOW 25KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...ROLFSON
MARINE...KC/TITUS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1231 PM CDT MON SEP 3 2012
.UPDATE...SENT AN UPDATE TO THE FORECAST TO INCREASE CLOUD COVER
THROUGH THE REMAINDER OF THE AFTERNOON HOURS AS LATEST SATELLITE
IMAGERY INDICATES A NICE BAND OF MID/UPPER LEVEL CLOUD
COVER...ASSOCIATED WITH WEAK FRONTAL BOUNDARY ACROSS THE AREA...
EXTENDS SOUTHWESTWARD ACROSS NORTHWESTERN KANSAS AND INTO
COLORADO. WITH THE INCREASED CLOUD COVER...A FEW LIGHT
SHOWERS/SPRINKLES AND AN ISOLATED EMBEDDED THUNDERSTORM...ALSO
TRENDED DOWN AFTERNOON FORECAST TEMPS A FEW DEGREES. NO OTHER
CHANGES NECESSARY TO INHERITED FORECAST AT THIS TIME.
.AVIATION...18Z KGRI TAF...PREVAILING VFR CONDITIONS WITH
GENERALLY LIGHT WINDS ARE EXPECTED TO PERSIST AT KGRI FOR THE
MAJORITY OF THE NEXT 24 HOURS...WITH AN ISOLATED SHOWER OR
THUNDERSTORM POSSIBLE...BUT NOT EXPECTED...THROUGH THE AFTERNOON
HOURS TODAY. AS A RESULT...KEPT BKN MID LEVEL CLOUD DECK WITH A
VCSH POSSIBLE NEAR THE TERMINAL THROUGH 04/00Z...WITH CLOUDS
SLOWLY SCATTERING THEREAFTER. SOME INDICATION THAT WITH LIGHT
WINDS...CLEARING SKIES AND ELEVATED DEW POINTS OVERNIGHT THAT WE
COULD SEE SOME PATCHY FOG DEVELOPMENT...BUT BELIEVE CLOUD COVER
OVERNIGHT WILL BE SUFFICIENT TO PREVENT MAXIMUM RADIATIVE COOLING
AND KEPT MENTION OF BR OUT 18Z TAF FOR THE TIME BEING.
&&
.PREV DISCUSSION... /ISSUED 345 AM CDT MON SEP 3 2012/
SHORT TERM...THROUGH 12Z THURSDAY. OVERNIGHT UPPER AIR ANALYSIS
INDICATES A LONG WAVE RIDGE OVER THE EASTERN CONUS AND A TROUGH
OVER THE WEST. SOUTHWESTERLY TO ZONAL MID AND UPPER LEVEL FLOW
EXISTS OVER THE MUCH OF THE CENTRAL CONUS AS A RESULT. MID AND
UPPER LEVEL JET ENERGY EXTENDS FROM SOUTHERN
CALIFORNIA...NORTHEAST INTO THE NORTHERN PLAINS AND PORTIONS OF
THE CENTRAL PLAINS...AS WELL AS SOUTHERN CANADA...AND THEN
SOUTHEAST INTO THE NORTHEASTERN CONUS. A ~90KT UPPER LEVEL JET
STREAK IS ALSO EVIDENT OVER THE CENTRAL AND NORTHERN ROCKY
MOUNTAIN RANGE. WATER VAPOR IMAGERY INDICATES INCREASED LEVELS OF
MID LEVEL MOISTURE EXTENDING NORTHWARD FROM MEXICO INTO THE
SOUTHWESTERN CONUS...AND THEN NORTHEAST INTO THE CENTRAL PLAINS.
AT THE SURFACE A WEAK COLD FRONT EXTENDS FROM NORTHEAST NEBRASKA
TO SOUTHWEST KANSAS. THE LOW LEVEL WIND FIELD REMAINS FROM THE
SOUTHEAST ACROSS SOUTHEASTERN PORTIONS OF THE OUR CWA...WITH MORE
OF A NORTHERLY LOW LEVEL WIND FIELD NOTED FARTHER NORTHWEST ACROSS
THE AREA BEHIND THE FRONT.
GUIDANCE FROM THE NAM AND OPERATIONAL GFS CONTINUE TO SUGGEST THE
UPPER LEVEL JET STREAK...CURRENTLY OVER THE CENTRAL AND NORTHERN
ROCKY MOUNTAIN RANGE...WILL CONTINUE MOVING EAST/NORTHEAST
TODAY...WITH THE RIGHT-REAR QUADRANT OF THIS JET STREAK SETTING UP
SHOP OVER NORTHERN PORTIONS OF OUR CWA. QPF FIELDS FROM THE
NAM...OPERATIONAL GFS AND SREF-MEAN...AS WELL AS SIMULATED
REFLECTIVITY FROM THE 4KM WRF-NMM AND HRRR ALL SUGGEST ENOUGH OF A
DIRECT THERMAL CIRCULATION AND RESULTANT FRONTOGENESIS WILL BE
PRESENT FOR ISOLATED TO SCATTERED PRECIPITATION PRODUCTION OVER
NORTHERN PORTIONS OF OUR AREA THROUGH 18Z. THESE MODEL SOLUTIONS
HAVE BEEN FAIRLY CONSISTENCE SETS OF GUIDANCE THROUGH THE PAST
THREE DAYS AND AS A RESULT WILL GO AHEAD AND MAINTAIN 20%-30% POPS
MAINLY ACROSS NORTHERN PORTIONS OF OUR CWA THROUGH 18Z. GUIDANCE
SUGGESTS THE UPPER LEVEL JET STREAK WILL WEAKEN AND PUSH
EAST/NORTHEAST OF OUR AREA BY THIS AFTERNOON...WHICH WOULD
OTHERWISE BRING AND END TO THE PRECIPITATION CHANCES ACROSS OUR
AREA. THAT BEING SAID...THERE REMAIN INDICATIONS FROM THE NAM AND
OPERATIONAL GFS OF MULTIPLE SMALL SCALE MID LEVEL PERTURBATIONS
PUSHING NEAR OR OVER THE AREA THROUGH THIS AFTERNOON AND EVENING.
GIVEN THE WEAK FORCING AND DIFFICULTY IN ASSIGNING PRECIPITATION
CHANCES TO AN AREA GIVEN THE SUBTLE NATURE OF THESE SMALL SCALE
PERTURBATIONS...QPF FIELDS FROM THE NAM...OPERATIONAL
GFS...EC...AND SREF-MEAN ARE ALL OVER THE PLACE AND OFFER LITTLE
IN THE WAY OF HELP IN TRYING TO DETERMINE WHERE AFTERNOON
CONVECTION WILL MOST LIKELY BE REALIZED. YESTERDAY AT THIS TIME IT
WAS BELIEVED THE WEAK LOW LEVEL BAROCLINIC ZONE...CURRENTLY OVER
OUR AREA...WOULD SLOWLY DRIFT TO THE SOUTHEAST AND WOULD PROVIDE
ADDITIONAL LOW LEVEL CONVERGENCE FOR SURFACE-BASED CONVECTION
DURING THE AFTERNOON AND EARLY EVENING HOURS. HOWEVER NOW IT
APPEARS THIS BAROCLINIC ZONE WILL QUICKLY EXIT OUR AREA TO THE
SOUTHEAST BY EARLY AFTERNOON AND WILL OFFER LITTLE IN THE WAY OF
ADDITIONAL FORCING FOR CONVECTIVE INITIATION. LONG STORY
SHORT...CONFIDENCE IS VERY LOW REGARDING MEASURABLE PRECIPITATION
BEING REALIZED AT ANY ONE LOCATION ACROSS THE CWA THIS AFTERNOON
AND EVENING. BUT BECAUSE MOST ALL MODELS SUGGEST AT LEAST SOME
ISOLATED CONVECTIVE ACTIVITY WILL BE OBSERVED...AGAIN NO TELLING
WHERE FOR SURE...WILL GO AHEAD AND CARRY 20% POPS ACROSS THE
ENTIRE CWA 18Z MONDAY THROUGH 06Z TUESDAY. AS FOR SEVERE WEATHER
CHANCES THIS AFTERNOON AND EVENING...WILL CONTINUE TO DISREGARD
THE OPERATIONAL GFS WHICH SUGGESTS SURFACE DEW POINTS IN THE MID
70S WILL BE REALIZED ACROSS PORTIONS OF THE CWA THIS AFTERNOON.
BOIVERIFY SUGGESTS BCCONSALL CONTINUES TO BE A GOOD PERFORMER WITH
RESPECT TO SURFACE DEW POINTS ACROSS OUR AREA AND THIS SET OF
GUIDANCE SUGGESTS AFTERNOON DEW POINTS WILL REMAIN GENERALLY IN
THE LOW TO MID 60S ACROSS OUR AREA...WITH PERHAPS A FEW UPPER 60
READINGS ACROSS OUR EAST...WHICH IS ALSO WHAT THE NAM CONTINUES TO
SUGGEST. FOLLOWING CLOSER TO THE NAM WOULD ALSO SUGGEST 0-1KM
MLCAPE VALUES OF ~1000J/KG WILL BE IN PLACE ACROSS THE AREA THIS
AFTERNOON AND EVENING. NOT THAT THESE POTENTIAL INSTABILITY VALUES
ARE SOMETHING TO GET OVERLY EXCITED ABOUT BUT WITH THE UPPER LEVEL
JET AXIS OVER THE AREA...DEEP LAYER BULK SHEAR VALUES ON THE ORDER
OF 40KTS WILL ALSO LIKELY BE PRESENT. ALTHOUGH INITIAL UPDRAFT
STRENGTH WILL LIKELY BE MARGINAL AT BEST FOR LARGE HAIL
PRODUCTION...THE ROTATIONAL POTENTIAL OF SAID UPDRAFT MAY ENHANCE
IT ENOUGH FOR A BETTER HAIL THREAT. GIVEN ALL THIS...IT STILL
SEEMS POSSIBLE THAT UPDRAFT STRENGTH COULD BE STRONG ENOUGH TO
SUPPORT LARGE HAIL AND AS A RESULT...WILL GO AHEAD AND CONTINUE TO
OUTLOOK THE AREA FOR POSSIBLE SEVERE WEATHER THIS AFTERNOON AND
EVENING. LOSS OF DIABATIC HEATING POST-SUNSET SHOULD KILL ANY
CONVECTION BEYOND 03Z THIS EVENING...WITH AN OVERALL LACK IN
KINEMATIC FORCING LIKELY PROVIDING DRY CONDITIONS TO THE AREA 03Z-
18Z TUESDAY.
GUIDANCE FROM THE NAM...OPERATIONAL GFS...AND EC ALL SUGGEST A
MORE SIGNIFICANT MID LEVEL SHORT WAVE WILL PUSH INTO SOUTH CENTRAL
CANADA AND PORTIONS OF THE NORTH CENTRAL CONUS TUESDAY INTO
TUESDAY NIGHT. A RESULTANT AREA OF SURFACE LOW PRESSURE IS
EXPECTED TO PUSH ACROSS THE NORTHERN PLAINS AND UPPER MISSISSIPPI
VALLEY DURING THE SAME TIME PERIOD...WITH AN ASSOCIATED SURFACE
COLD FRONT EXPECTED TO SWEEP ACROSS NEBRASKA. AT THIS TIME THE LOW
LEVEL BAROCLINIC ZONE IS EXPECTED TO NEAR NORTH/NORTHWESTERN
PORTIONS OF OUR CWA BY 00Z WEDNESDAY...LIKELY CLEARING THE ENTIRE
CWA BY 12Z WEDNESDAY. SURFACE-BASED CONVECTION WILL BE POSSIBLE IN
THE VICINITY OF THIS LOW LEVEL BAROCLINIC ZONE ACROSS OUR
NORTH/NORTHWEST BY LATE AFTERNOON TUESDAY...WITH ADDITIONAL
CONVECTIVE ACTIVITY PERHAPS SPREADING SOUTHEAST ACROSS THE CWA
HEADING INTO THE EVENING AND OVERNIGHT HOURS TUESDAY. GIVEN ALL
THIS...WILL GO AHEAD WITH 20%-30% POPS ACROSS THE CWA 21Z TUESDAY
THROUGH 12Z WEDNESDAY. POOLING OF LOW LEVEL MOISTURE AHEAD OF THE
LOW LEVEL BAROCLINIC ZONE...AS SUGGESTED BY THE NAM...MAY ACTUALLY
HELP TO INCREASE POTENTIAL INSTABILITY ACROSS OUR AREA WHEN
COMPARED TO MONDAY...WITH THE NAM SUGGESTING 0-1KM MLCAPE VALUES
ON THE ORDER OF 1500J/KG POSSIBLE TUESDAY AFTERNOON INTO THE
EVENING HOURS. IN ADDITION...DEEP LAYER BULK SHEAR VALUES OF
AROUND 35KTS WILL ALSO BE IN EXISTENCE. GIVEN ALL THIS...WILL
CONTINUE THE SEVERE WEATHER MENTION IN THE HWO FOR TUESDAY.
A COOLER AND DRIER AIRMASS WILL SETTLE IN ACROSS THE AREA BEHIND
THE LOW LEVEL BAROCLINIC ZONE WEDNESDAY AND WEDNESDAY NIGHT...AND
AN OVERALL LACK IN KINEMATIC FORCING SHOULD PRESENT DRY CONDITIONS
TO OUR AREA 12Z WEDNESDAY THROUGH 12Z THURSDAY.
AN EASTERLY COMPONENT TO THE LOW LEVEL WIND FIELD AND A SLIGHTLY
COOLER AIRMASS WILL PRESENT COOLER CONDITIONS TO THE AREA TODAY
WHEN COMPARED TO SUNDAY...WITH AFTERNOON HIGHS IN THE LOW TO MID
90S EXPECTED THROUGH MOST LOCATIONS. WARMER WEATHER AHEAD OF THE
APPROACHING LOW LEVEL BAROCLINIC ZONE WILL LIKELY PRESENT
AFTERNOON HIGHS IN THE MID TO UPPER 90S ON TUESDAY. THE COOLER
AIRMASS ON WEDNESDAY WILL LIKELY KEEP AFTERNOON HIGHS IN THE 80S
TO FINISH OUT THE SHORT TERM FORECAST PERIOD. OVERNIGHT LOWS IN
THE 60S WILL REMAIN THE NORM MONDAY NIGHT AND TUESDAY NIGHT...WITH
THE COOLER AIRMASS LIKELY PROMOTING TEMPERATURES IN THE 50S
WEDNESDAY NIGHT INTO THURSDAY MORNING.
LONG TERM...THURSDAY THROUGH SUNDAY. PRIMARY FORECAST CONCERNS
LIE WITH END OF THE WEEK PRECIPITATION CHANCES...AND TEMPERATURES.
THE START OF THE LONG TERM PERIOD SHOWS MODELS NOT IN TOO BAD OF
AGREEMENT WITH THE PATTERN ACROSS THE CONUS...WHICH REMAINS
ZONAL...SET UP BETWEEN BROAD HIGH PRESSURE EXTENDING ACROSS THE
DESERT SW AND SRN PLAINS...WHILE A LARGE LOW PRESSURE SYSTEM SPINS
OVER CENTRAL CANADA. THROUGH THE END OF THE WORK
WEEK...PRECIPITATION CHANCES CONTINUE ACROSS THE CWA...DRIVEN BY A
COUPLE OF DISTURBANCES ASSOCIATED WITH THAT CANADIAN LOW PRESSURE
SYSTEM. THE FIRST ONE LOOKS TO AFFECT THE AREA MAINLY ON
THURSDAY/THURSDAY NIGHT...ALSO PUSHING A SURFACE BOUNDARY INTO
ROUGHLY THE NORTHERN HALF OF THE CWA DURING THE AFTERNOON HOURS.
THE SECOND DISTURBANCE...DIVING BASICALLY STRAIGHT SOUTH OUT OF
CANADA...AFFECTS THE AREA MAINLY FRIDAY/FRIDAY EVENING. KEPT POPS
CWA-WIDE THURS/THURS NIGHT/FRI...WITH ONLY A FEW LINGERING POPS
INTO FRIDAY NIGHT ACROSS NC KS...AND IF CURRENT MODEL TRENDS
CONTINUES...THOSE FRIDAY EVENING/NIGHT POPS COULD BE REMOVED. AS
MENTIONED...THURSDAY SEE THE INITIAL FRONT MOVE INTO THE CWA...BUT
THAT SECOND DISTURBANCE WILL USHER IN A REINFORCING COLD
FRONT...ACCOMPANIED BY THE COOLER/DRIER AIR FOR FRIDAY. FORECAST
HIGHS FOR THURSDAY SIT IN THE 80S...WHILE FRIDAY IS IN THE MID
70S/LOWER 80S. WILL KEEP THE MENTION OF SOME STRONG/SEVERE
THUNDERSTORMS GOING FOR THIS PERIOD WITH MODELS CONTINUING TO SHOW
THE POTENTIAL FOR DECENT INSTABILITY/SHEAR IN THE AREA.
PLEASANT CONDITIONS ON TAP FOR THE UPCOMING WEEKEND...WITH MODELS
DEPICT DRIER NORTHWESTERLY FLOW SETTING UP IN THE UPPER LEVELS
ACROSS THE CENTRAL PLAINS...SITTING BETWEEN THE TROUGH/LOW OVER
THE GREAT LAKES AND MIDWEST...WHILE RIDGING BUILDS INTO THE
ROCKIES. HIGH PRESSURE LOOKS TO BE THE PRIMARY PLAYER AT THE
SURFACE...BUILDING IN FROM THE NORTHWEST BEHIND THE END OF THE
WORK WEEK FRONTAL PASSAGE. EXPECTING TO SEE PLENTY OF
SUNSHINE...WITH FAIRLY LIGHT WINDS /ESP ON SAT/. THE AREA OF SFC
HIGH PRESSURE LOOKS TO BE CENTERED RIGHT OVER THE CWA ON
SATURDAY...BEFORE SLIDING OFF SLIGHTLY TO THE EAST ON SUNDAY...AND
EXPECTING SATURDAY TO BE A TOUCH COOLER THAN SUNDAY. CURRENT
FORECAST HIGHS ON SATURDAY SIT IN THE MID 70S...WITH SUNDAY
CREEPING UP INTO THE UPPER 70S TO LOWER 80S...BOTH DAYS FEELING
PRETTY NICE WITH DEWPOINTS LOOKING TO BE IN THE 40S FOR MOST
LOCATIONS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AVIATION/UPDATE...ROSSI
SHORT TERM...BRYANT
LONG TERM...ADO
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
147 PM EDT MON SEP 3 2012
.SYNOPSIS...
THE REMNANTS OF ISAAC WILL EFFECT THE REGION THROUGH TUESDAY
NIGHT. BRIEF DRY AIR CAN BE EXPECTED FOR WEDNESDAY. A WEAK COLD
FRONT ARRIVES THURSDAY...FOLLOWED BY LOW PRESSURE FOR NEXT WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
1030 AM UPDATE. CONFIDENCE LOW TO MEDIUM. HAVE INCREASED POPS IN THE
EAST THIS AFTERNOON AND MAINTAINED FF WATCH IN THE NORTH. WILL TWEAK
TEMPS DOWN JUST A BIT IN THE WEST WITH THE CLOUDS.
VERY TROPICAL AND MOIST ADIABATIC ATMOSPHERE WITH PW`S ABOVE 2
INCHES SUGGESTS THAT IT WILL NOT TAKE MUCH TO INITIATE CONVECTION DUE
TO HEATING AND ANY VORT MAX ROTATING AROUND THE REMAINS OF ISAAC
CENTERED OVER CENTRAL KENTUCKY AT TIME. PROBLEM IS THE LARGE SHIELD
OF CLOUDS REMAINING OVER THE CWA FROM RAPIDLY DYING ELEVATED INDUCED
SHOWERS FROM THE WEST...AND IN TRYING TO DETERMINE THE MODEL
INDICATED VORT MAXES THAT WILL BE ENOUGH TO FORCE CONVECTION IN
SPITE OF THE CLOUDS. CURRENT INDICATIONS BY SATELLITE AND RADAR ARE
THAT SUNSHINE WILL BE LIMITED THIS AFTERNOON SINCE ANY DECREASE IN
MID LEVEL CLOUDS WILL QUICKLY BE REPLACED BY A CU SHIELD...WITH BEST
BREAKS IN THE EAST. BOTTOM LINE IS THAT POPS IN THE WEST WILL NOT BE
REDUCED GIVEN UNCERTAINTY AND RAISED IN THE EAST WITH MORE CLOUD
BREAKS. ANY STORM COULD PRODUCE LOCALLY HEAVY RAIN.
630AM UPDATE...
TWEAKED POPS TO ACCOUNT FOR ONGOING PCPN BAND ACROSS SE OH. STILL
LOOKING FOR AFTN DEVELOPMENT AFTER SOME OF THE CLDS BURN OFF SOME.
LATEST HRRR SHOWS THIS DEVELOPMENT ARND 18Z ACROSS W AND S...AND
ROTATING THRU LATER IN AFTN.
PREVIOUS DISCUSSION BELOW...
CIRCULATION WITH ISAAC TO SLOWLY CONT TO MOVE SE THRU C KY AND TN
IN THE NEAR TERM. AS IT DOES SO IT WILL ALSO CONT TO
WEAKEN...OPENING UP INTO A BROAD TROF TONIGHT. STILL ROLLING WITH
CONSENSUS PLACEMENT OF H5 VORT/MID LVL DEFORMATION AXIS FOR
PLACEMENT AND TIMING OF POPS FROM BANDS SPIRALING INTO AREA. ONE
SUCH BAND CONT TO WEAKEN ACROSS EASTERN KY...STRUGGLING TO MAKE
MUCH E PROGRESS. THINK SOME ADDITIONAL DEVELOPMENT MAY FORM JUST
AHEAD OF WHAT IS LEFT OF THIS BAND WITH LINGERING INSTABILITY
NOTED ACROSS THE CWA. WILL FINESSE DETERMINISTIC POPS FOR THIS
EARLY MORNING WITH THIS THINKING IN MIND...HOLDING CAT AND LKLY
POPS ACROSS W AND S ZONES. TRACK THIS N THRU CWA AFTER SUNRISE
WITH YET ANOTHER BAND POISED TO ROTATE THRU LATER IN THE DAY. AS
SUCH DONT EXPECT WASHOUT OF A DAY...WITH SOME LULLS IN BETWEEN.
QPF TDY DEPENDENT ON HOW CONVECTIVE THE ACTION IS. WITH PWATS
STILL RUNNING ABV 2 INCHES...POTENTIAL EXISTS FOR SOME LCL 1 TO 2
INCHES OF RAIN...WITH A GENERAL HALF INCH TO INCH EXPECTED MOST
PLACES. FFG CONT TO RUN ON HIGH SIDE ACROSS NE KY DOWN THRU SW WV
AND SW VA WITH LWR VALUES ACROSS SE OH INTO C AND N WV. IT IS THIS
AREA THAT IS OF CONCERN...AS 1.5 TO 2.5 INCHES OF RAIN FELL THERE
YESTERDAY. GIVEN THAT...AND ENOUGH CONFIDENCE ON PLACEMENT OF VORT
THIS AFTN AND EVE ACROSS ESPECIALLY SE OH...WILL HOIST A FLASH
FLOOD WATCH THRU THIS EVENING FOR NORTHERN TIER OF CO FROM PERRY
TO HARRISON.
EXPECT ACTION TO WANE AFTER SUNSET WITH LOSS OF HEATING. HOWEVER
WITH A COUPLE MORE SPOKES PROGGED ON MDLS TO MOVE THRU OVERNIGHT
TONIGHT...KEPT SOME CHC POPS IN. THINK SOME LOW STRATUS WILL BE IN
THE CARDS TONIGHT AS WELL...LESS SO PERHAPS OVER C WV DUE TO WEAK DOWNSLOPING.
GUIDANCE TIGHTLY CLUSTERED FOR TEMPS...SO ROLLED WITH A BLEND.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
MOISTURE FROM ISAAC REMAINS OVER THE AREA ON TUESDAY. MODEL
SOUNDINGS CONTINUE TO LOOK VERY UNSTABLE. THEREFORE WILL GO WITH
LIKELY POPS DURING THE AFTERNOON HOURS. THE MOISTURE FINALLY PUSHES
EAST OF THE AREA TUESDAY NIGHT AND EARLY WEDNESDAY. THEREFORE...WILL
REMOVE POPS ON WEDNESDAY AFTERNOON. A WEAK MOISTURE STARVED COLD
FRONT PUSHES INTO THE AREA ON THURSDAY. PRECIPITATION LOOKS VERY
IFFY...SO WILL KEEP ONLY VERY SMALL POPS WITH THE FRONT.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
SOME RESIDUAL MOISTURE REMAINS IN PLACES AS WEAK SURFACE HIGH
PRESSURE BUILDS OVER THE FORECAST AREA. BY DAY 7 MODELS SHOW SHOW
SOME MODEST SPREAD WITH TROUGH DIGGING INTO THE UPPER MIDWEST WITH
BAROCLINIC APPROACHING FROM THE WEST. BOTH GFS AND EURO MODEL
GENERALLY CLOSE WITH TIMING THE NEXT FEATURE ACROSS. FOLLOWED HPC
POP AND TEMP TRENDS WITH MINOR ADJUSTMENTS.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
18Z MONDAY THRU 18Z TUESDAY...
THROUGH THIS AFTERNOON...VFR CEILINGS OUTSIDE CONVECTION.
CONVECTION INCREASES WITH SFC HEATING...ESPECIALLY IN THE MOUNTAINS.
THUS INSERTED TEMPO GROUPS FOR THUNDER...ESPECIALLY MOUNTAINS.
TONIGHT...ACTIVITY WANES WITH SUNSET BUT STILL SCATTERED CONVECTION
OVERNIGHT...ESPECIALLY MOUNTAINS. GRADUALLY BRING CIGS DOWN INTO MVFR
RANGE AS LLVL MOISTURE SHIELD ENCROACHES UPON THE AREA. COULD ALSO
SEE SOME IFR CIGS ON THE EASTERN SLOPES ON SE UPSLOPE FLOW AND IN
PROTECTED VALLEYS THAT RECEIVE RAIN.
AFTER 12Z TUESDAY...BECOMING VFR CEILINGS BY 15Z. WIDELY SCATTERED
TO SCATTERED CONVECTION CONTINUES...INCREASING AFTER 18Z.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z TUESDAY...
FORECAST CONFIDENCE: LOW TO MEDIUM.
ALTERNATE SCENARIOS: TIMING OF SHOWERS AND THUNDERSTORMS COULD VARY.
STRATUS AND FOG TONIGHT COULD VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H M M
EKN CONSISTENCY H H H H H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H M
AFTER 18Z TUESDAY...
IFR IN HEAVY SHOWERS AND THUNDERSTORMS POSSIBLE WITH THE REMNANTS OF
TROPICAL STORM ISAAC AT TIMES THROUGH TUESDAY NIGHT.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...FLASH FLOOD WATCH UNTIL 11 PM EDT THIS EVENING FOR WVZ010-011-
020-031.
OH...FLASH FLOOD WATCH UNTIL 11 PM EDT THIS EVENING FOR OHZ066-067-
076.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30
NEAR TERM...JMV/30
SHORT TERM...RPY
LONG TERM...KMC
AVIATION...JMV
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
315 PM CDT MON SEP 3 2012
.DISCUSSION.../ISSUED AT 315 PM CDT/
LIGHT SHOWERS MAINLY CONFINED TO NORTHWEST IOWA SO FAR THIS
AFTERNOON. MID LEVEL CLOUDS ALSO DISSIPATING IN OUR WEST ALLOWING
FOR DECENT HEATING. DEWPOINTS HAVE FALLEN RAPIDLY ONCE MIXING
COMMENCED...WITH DRY AIR ALOFT. THIS WAS SHOWN WELL BY THE HRRR AND
NAM. BOTH OF THESE MODELS SHOW SOME DEWPOINT RECOVERY BY LATER THIS
AFTERNOON RIGHT AHEAD OF THE APPROACHING FRONTAL BOUNDARY. THE
QUESTION IS WHETHER THEY RECOVER ENOUGH TO HELP BREAK THE CAP. HRRR
HAS BACKED OFF SOME OF ITS EARLIER IDEA OF SCATTERED TO NUMEROUS
STORMS FORMING AS THE BOUNDARY ENTERED OUR CWA. STILL THINKING WE
POSSIBLY GET SOME ISOLATED DEVELOPMENT AFTER 4 OR 5 PM WEST OF THE
JAMES RIVER. FULL SUN COMBINED WITH CONVERGENCE ALONG THE FRONT AND
AN APPROACHING SHORTWAVE...MAY BE ENOUGH TO AT LEAST GET ISOLATED
DEVELOPMENT. CAPE COULD BE AROUND 1500 J/KG NEAR THE BOUNDARY...AND
A VEERING WIND PROFILE WITH DECENT WINDS ALOFT SHOULD RESULT IN
AROUND 40 KTS EFFECTIVE SHEAR. SO ANY STORM THAT IS ABLE TO FORM
COULD BE SEVERE...WITH STRONG WINDS AND LARGE HAIL. STORMS WOULD
MOVE EAST OR EAST SOUTHEAST...BUT THINKING MOST ACTIVITY WILL BE
DIURNALLY DRIVEN AND THUS DIE AS THE EVENING PROGRESSES. KEPT CHANCE
POPS MAINLY ALONG AND WEST OF THE JAMES RIVER....WITH SLIGHT CHANCE
THROUGH THE REST OF THE CWA...JUST IN CASE STORMS PERSIST ALONG
THERE OUTFLOW LONGER THAN EXPECTED. SKIES SHOULD CLEAR LATER
TONIGHT...WITH LOWS IN THE 50S AND 60S. COULD SEE SOME FOG
DEVELOPMENT IN THE SOUTH...ESPECIALLY WHERE RAIN HAS FALLEN TODAY IN
NORTHWEST IOWA.
TUESDAY SHOULD START MOSTLY SUNNY WITH HIGHS IN THE 80S AND 90S.
TRICKY PART OF TUESDAYS FORECAST WILL BE HOW FAR SOUTH THE BOUNDARY
MAKES IT LATE TONIGHT...AND HOW QUICKLY IT PUSHES BACK NORTH AS A
WARM FRONT TOMORROW BEFORE THE COLD FRONT PUSHES THROUGH. WITH
STABLE DRIER AIR NORTH OF THIS BOUNDARY...CONVECTION CHANCES WILL BE
CONFINED TO ALONG AND SOUTH OF IT DURING THE DAY...AS ANOTHER
SHORTWAVE PUSHES ACROSS. NAM IS THE FURTHEST SOUTH WITH THE
BOUNDARY...ONLY PUSHING AS FAR NORTH AS SPENCER TO YANKTON BY
AFTERNOON. THE GFS IS FURTHEST NORTH...WITH THE ECMWF IN BETWEEN.
NAM HAS BEEN A LITTLE TOO AGGRESSIVE WITH FRONTS...BUT GENERALLY HAS
BEEN THE BEST. THUS TEND TO THINK A SOLUTION SOMEWHERE BETWEEN THE
ECMWF AND NAM WILL BE CLOSEST. THIS WOULD GENERALLY KEEP THE
THUNDERSTORM THREAT SOUTH OF INTERSTATE 90 THROUGH 7 PM TUESDAY.
STORMS THAT DO FORM IN THE AFTERNOON WILL HAVE THE POTENTIAL OF
BEING SEVERE...WITH AROUND 2000 J/KG OF CAPE AND DEEP LAYER SHEAR OF
40 KTS. LARGE HAIL AND STRONG WINDS WILL BE POSSIBLE IN ANY STORM
THAT DOES FORM. CAP SHOULD HOLD STRONG FOR MUCH OF THE
AFTERNOON...HOWEVER CONTINUED HEATING AND THE APPROACHING WAVE
SHOULD BREAK IT AT SOME POINT EITHER LATE AFTERNOON OR EVENING.
/CHENARD
THAT APPROACHING WAVE AND FRONT SHOULD BRING MORE NUMEROUS SHOWERS
AND THUNDERSTORMS TUESDAY EVENING...MAINLY TO THE EASTERN PART OF
THE AREA WHERE MOISTURE POOLING AND INFLOW WILL BE GOOD. SYSTEM
MOVING FAST ENOUGH AND MID TO UPPER FLOW IS STRONG ENOUGH SO THAT
RAINFALL AMOUNTS SHOULD NOT BE TOO HIGH. FRONT WILL BE MOVING ACROSS
AREA WITH COOLER AIR SPREADING IN BEHIND IT...AND PRECIPITATION
DECREASING STEADILY AFTER MIDNIGHT. GUIDANCE SEEMS OK AT THIS POINT
ON COOLING FOR LOW TEMPERATURES. MOVEMENT LOOKS FAST ENOUGH TO KEEP
OUT ANY MENTION OF LINGERING SHOWERS FOR WEDNESDAY AND DRYING
CERTAINLY LOOKS STRONG...SO WE SHOULD BE HEADING TO A SUNNY/MOSTLY
SUNNY DAY WEDNESDAY AFTER MORNING CLOUDS SOUTHEAST DECREASE. LATE
THURSDAY INTO FRIDAY LOOKS LIKE ANOTHER THREAT OF SHOWERS AND STORMS
AS NEXT WAVE AND COLD FRONT IS PRECEDED BY FAVORABLY THERMAL
ADVECTION PATTERN. WILL GO WITH LOW POPS AS PER GUIDANCE FOR NOW BUT
OVERALL THREAT SEEMS A LITTLE HIGHER AND WHEN WE CAN NARROW DOWN THE
TIMING BETTER...THE POPS FOR AT LEAST PART OF THAT TIME...PERHAPS
THURSDAY NIGHT...MAY GO UP. THIS SYSTEM WILL BRING IN EVEN COOLER
AIR FOR FRIDAY AND SATURDAY. SOLIDLY DRY PATTERN WILL ALSO DEVELOP
BEHIND THIS SYSTEM...AND THE DRY PATTERN WILL REMAIN IN PLACE AS
SLOW BUT STEADY WARMING SETS IN SUNDAY AFTERNOON THROUGH MONDAY.
&&
.AVIATION.../FOR THE 18Z TAF ISSUANCE/
GENERALLY VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. THE
POTENTIAL EXISTS FOR THUNDERSTORM DEVELOPMENT THIS AFTERNOON WEST OF
THE JAMES RIVER AFTER 4 PM. ANY STORMS THAT FORM COULD PRODUCE
MVFR/IFR CONDITIONS AND ERRATIC WINDS. LOW CONFIDENCE ON WHETHER
STORMS FORM...THUS LEFT OUT OF THE TAFS FOR NOW. BEST CHANCE WOULD
BE BETWEEN 5 PM AND 7 PM AT KHON...WITH AN EVEN LOWER CHANCE IN THE
INTERSTATE 29 CORRIDOR CLOSER TO 10 PM. WITH LOW LEVEL MOISTURE
POOLING...COULD ALSO SEE SOME POCKETS OF MVFR FOG
TONIGHT...ESPECIALLY IN ANY AREAS THAT GET SOME RAIN TODAY...BUT
WILL LET FUTURE SHIFTS ADD IN IF CONFIDENCE INCREASES. /CHENARD
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
$$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1217 PM CDT MON SEP 3 2012
.DISCUSSION.../ISSUED AT 1120 AM CDT/
DECENT AREA OF MID LEVEL CLOUDS CURRENTLY OVER THE AREA. SEEING A
FEW LIGHT SHOWERS ACROSS THE FAR SOUTH AND WEST AT THIS TIME...AND
EVEN SOME LIGHTNING TOWARDS THE JAMES RIVER. THINKING THAT THESE MID
LEVEL CLOUDS CONTINUE TO PUSH EAST AND THIN SOME THROUGH THE
DAY...WITH MOST OF THE SHOWER ACTIVITY ENDING. THUS KEPT HIGH
TEMPERATURES AS ARE FOR NOW...BUT IF CLOUDS STICK AROUND SOME AREAS
MAY STRUGGLE TO REACH FORECASTED HIGHS. OTHER CONCERN TODAY IS
AFTERNOON CONVECTION POTENTIAL. MODEL SHOW ACTIVITY DEVELOPING ALONG
A BOUNDARY ACROSS EASTERN NEBRASKA INTO PORTIONS OF IOWA THIS
AFTERNOON. THINKING MOST OF THIS SHOULD STAY SOUTH AND EAST OF OUR
CWA...AND WITH CLOUD COVER LIMITING INSTABILITY...NOT SURE HOW
ROBUST THAT ACTIVITY WOULD BE EVEN IF IT CLIPPED OUR FAR SOUTHEAST.
OTHER AREA TO WATCH WILL BE ALONG AN APPROACHING COLD FRONT FROM THE
WEST THIS AFTERNOON. HRRR AND HIGH RES NAM HAVE CONTINUED TO SHOW
THE CAP BREAKING ALONG THIS BOUNDARY THIS AFTERNOON IN OUR
WEST...GENERALLY AFTER 4 PM. IT APPEARS LIKE DAYTIME
HEATING...COMBINED WITH LIFT ALONG THE FRONT AND SOME WEAK UPPER
LEVEL SUPPORT ARE ENOUGH FOR THE MODELS TO BREAK THE CAP. MAIN
UNCERTAINTY WILL BE HOW MUCH HEATING DOES OCCUR ALONG AND WEST OF
THE JAMES RIVER THIS AFTERNOON. HRRR BREAKS THE CAP WITH LOW TO MID
90S TEMPERATURES AND MID 50S TO AROUND 60 DEWPOINTS. LATEST VISIBLE
IMAGE DOES SHOW CLOUDS CLEARING IN THAT AREA...SO REACHING THE ABOVE
VALUES DOES SEEM POSSIBLE. STEEP LAPSE RATES SHOULD RESULT IN CAPE
AROUND 1500 J/KG JUST AHEAD OF THE AFTERNOON BOUNDARY...WITH A
DECENT VEERING WIND PROFILE RESULTING IN UP TO 40 KTS OF EFFECTIVE
SHEAR. THUS IT SEEMS REASONABLE THAT ANY STORMS THAT FORM COULD BE
SEVERE...WITH STRONG WINDS THE MAIN THREAT. ALTHOUGH GIVEN THE LAPSE
RATES AND SHEAR...SOME LARGE HAIL IS ALSO POSSIBLE. STORMS SHOULD
TEND TO WEAKEN BY THE TIME THEY REACH INTERSTATE 29...ALTHOUGH IF
STORMS ARE ABLE TO ORGANIZE ALONG THERE OUTFLOW...CAN NOT RULE OUT
THEM MAKING IT THAT FAR EAST. AGAIN...STORM INITIATION IS LOW
CONFIDENCE...BUT GIVEN HRRR AND OTHER HIGH RES MODEL
CONSISTENCY...WILL HAVE TO WATCH CLOSELY AS WE HEAD INTO THIS
AFTERNOON. /CHENARD
&&
.AVIATION.../FOR THE 18Z TAF ISSUANCE/
GENERALLY VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. THE
POTENTIAL EXISTS FOR THUNDERSTORM DEVELOPMENT THIS AFTERNOON WEST OF
THE JAMES RIVER AFTER 4 PM. ANY STORMS THAT FORM COULD PRODUCE
MVFR/IFR CONDITIONS AND ERRATIC WINDS. LOW CONFIDENCE ON WHETHER
STORMS FORM...THUS LEFT OUT OF THE TAFS FOR NOW. BEST CHANCE WOULD
BE BETWEEN 5 PM AND 7 PM AT KHON...WITH AN EVEN LOWER CHANCE IN THE
INTERSTATE 29 CORRIDOR CLOSER TO 10 PM. WITH LOW LEVEL MOISTURE
POOLING...COULD ALSO SEE SOME POCKETS OF MVFR FOG
TONIGHT...ESPECIALLY IN ANY AREAS THAT GET SOME RAIN TODAY...BUT
WILL LET FUTURE SHIFTS ADD IN IF CONFIDENCE INCREASES. /CHENARD
&&
.PREVIOUS DISCUSSION.../ISSUED AT 340 AM CDT/
WEAK SURFACE FRONT HAS STALLED ACROSS EASTERN CWA. UPPER LEVEL SHORT
WAVE ACROSS CENTRAL NEBRASKA AND MAY SPUR SOME ISOLATED SHOWER AND
THUNDERSTORM ACTIVITY AS WAVE ENCOUNTERS DEEPER MOISTURE AS IT WORKS
EAST. STILL FAR FROM A GREAT PRECIPITATION SET UP...AND BULK OF
FORCING ONLY SCRAPES THE SOUTHEASTERN CORNER OF THE FORECAST AREA.
AS SUCH...HAVE ONLY LEFT SLIGHT CHANCE POPS IN THE SOUTHEAST THROUGH
THE MORNING HOURS. MILD TEMPERATURES EXPECTED ACROSS THE AREA AGAIN
TODAY WITH 850 HPA TEMPS NEAR 20 C. FORECAST SOUNDINGS INDICATE THAT
ATMOSPHERE MAY HEAT OUT TO NEAR THE CONVECTIVE TEMP BY EARLY
AFTERNOON ACROSS CENTRAL SOUTH DAKOTA. THINK MODELS ARE OVERMIXING
SOME...BUT MAY BE CAPABLE OF A STORM OR TWO ACROSS THE WESTERN CWA
BY LATE AFTERNOON AS A WEAK BOUNDARY APPROACHES FROM THE WEST.
EXPECT CONVECTION TO DIE AWAY THROUGH THE EVENING HOURS AS
CONVECTION LOSES ITS HEATING SOURCE.
TUESDAY APPEARS TO BE THE LAST WARM DAY IN A WHILE WITH MUCH
STRONGER COLD FRONT EXPECTED TO WORK THROUGH THE AREA LATE TUESDAY
AFTERNOON INTO TUESDAY NIGHT. MUCH OF THE MIDLEVEL FORCING IS
FOCUSED ACROSS THE NORTHERN CWA...AND WITH THE LACK OF MOISTURE AM
CONCERNED PREVIOUS FORECAST WAS OVERDOING PRECIP POTENTIAL. LEFT
LIKELY MENTION IN THE NORTHEAST...BUT OTHERWISE SCALED EVERYTHING
BACK INTO THE CHANCE CATEGORY.
MUCH COOLER PATTERN SETTING UP FOR THE REMAINDER OF THE WEEK.
BREEZY NORTHWEST WINDS ARE EXPECTED ON WEDNESDAY WITH STRONG MIXING
AND DEEP NORTHWEST FLOW. A SERIES OF UPPER WAVES ARE EXPECTED TO
MOVE THROUGH THE AREA ON THURSDAY THROUGH SATURDAY...BUT WITH LACK
OF AVAILABLE MOISTURE SCALED BACK INHERITED POPS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
$$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1122 AM CDT MON SEP 3 2012
.DISCUSSION.../ISSUED AT 1120 AM CDT/
DECENT AREA OF MID LEVEL CLOUDS CURRENTLY OVER THE AREA. SEEING A
FEW LIGHT SHOWERS ACROSS THE FAR SOUTH AND WEST AT THIS TIME...AND
EVEN SOME LIGHTNING TOWARDS THE JAMES RIVER. THINKING THAT THESE MID
LEVEL CLOUDS CONTINUE TO PUSH EAST AND THIN SOME THROUGH THE
DAY...WITH MOST OF THE SHOWER ACTIVITY ENDING. THUS KEPT HIGH
TEMPERATURES AS ARE FOR NOW...BUT IF CLOUDS STICK AROUND SOME AREAS
MAY STRUGGLE TO REACH FORECASTED HIGHS. OTHER CONCERN TODAY IS
AFTERNOON CONVECTION POTENTIAL. MODEL SHOW ACTIVITY DEVELOPING ALONG
A BOUNDARY ACROSS EASTERN NEBRASKA INTO PORTIONS OF IOWA THIS
AFTERNOON. THINKING MOST OF THIS SHOULD STAY SOUTH AND EAST OF OUR
CWA...AND WITH CLOUD COVER LIMITING INSTABILITY...NOT SURE HOW
ROBUST THAT ACTIVITY WOULD BE EVEN IF IT CLIPPED OUR FAR SOUTHEAST.
OTHER AREA TO WATCH WILL BE ALONG AN APPROACHING COLD FRONT FROM THE
WEST THIS AFTERNOON. HRRR AND HIGH RES NAM HAVE CONTINUED TO SHOW
THE CAP BREAKING ALONG THIS BOUNDARY THIS AFTERNOON IN OUR
WEST...GENERALLY AFTER 4 PM. IT APPEARS LIKE DAYTIME
HEATING...COMBINED WITH LIFT ALONG THE FRONT AND SOME WEAK UPPER
LEVEL SUPPORT ARE ENOUGH FOR THE MODELS TO BREAK THE CAP. MAIN
UNCERTAINTY WILL BE HOW MUCH HEATING DOES OCCUR ALONG AND WEST OF
THE JAMES RIVER THIS AFTERNOON. HRRR BREAKS THE CAP WITH LOW TO MID
90S TEMPERATURES AND MID 50S TO AROUND 60 DEWPOINTS. LATEST VISIBLE
IMAGE DOES SHOW CLOUDS CLEARING IN THAT AREA...SO REACHING THE ABOVE
VALUES DOES SEEM POSSIBLE. STEEP LAPSE RATES SHOULD RESULT IN CAPE
AROUND 1500 J/KG JUST AHEAD OF THE AFTERNOON BOUNDARY...WITH A
DECENT VEERING WIND PROFILE RESULTING IN UP TO 40 KTS OF EFFECTIVE
SHEAR. THUS IT SEEMS REASONABLE THAT ANY STORMS THAT FORM COULD BE
SEVERE...WITH STRONG WINDS THE MAIN THREAT. ALTHOUGH GIVEN THE LAPSE
RATES AND SHEAR...SOME LARGE HAIL IS ALSO POSSIBLE. STORMS SHOULD
TEND TO WEAKEN BY THE TIME THEY REACH INTERSTATE 29...ALTHOUGH IF
STORMS ARE ABLE TO ORGANIZE ALONG THERE OUTFLOW...CAN NOT RULE OUT
THEM MAKING IT THAT FAR EAST. AGAIN...STORM INITIATION IS LOW
CONFIDENCE...BUT GIVEN HRRR AND OTHER HIGH RES MODEL
CONSISTENCY...WILL HAVE TO WATCH CLOSELY AS WE HEAD INTO THIS
AFTERNOON. /CHENARD
.PREVIOUS DISCUSSION.../ISSUED AT 340 AM CDT/
WEAK SURFACE FRONT HAS STALLED ACROSS EASTERN CWA. UPPER LEVEL SHORT
WAVE ACROSS CENTRAL NEBRASKA AND MAY SPUR SOME ISOLATED SHOWER AND
THUNDERSTORM ACTIVITY AS WAVE ENCOUNTERS DEEPER MOISTURE AS IT WORKS
EAST. STILL FAR FROM A GREAT PRECIPITATION SET UP...AND BULK OF
FORCING ONLY SCRAPES THE SOUTHEASTERN CORNER OF THE FORECAST AREA.
AS SUCH...HAVE ONLY LEFT SLIGHT CHANCE POPS IN THE SOUTHEAST THROUGH
THE MORNING HOURS. MILD TEMPERATURES EXPECTED ACROSS THE AREA AGAIN
TODAY WITH 850 HPA TEMPS NEAR 20 C. FORECAST SOUNDINGS INDICATE THAT
ATMOSPHERE MAY HEAT OUT TO NEAR THE CONVECTIVE TEMP BY EARLY
AFTERNOON ACROSS CENTRAL SOUTH DAKOTA. THINK MODELS ARE OVERMIXING
SOME...BUT MAY BE CAPABLE OF A STORM OR TWO ACROSS THE WESTERN CWA
BY LATE AFTERNOON AS A WEAK BOUNDARY APPROACHES FROM THE WEST.
EXPECT CONVECTION TO DIE AWAY THROUGH THE EVENING HOURS AS
CONVECTION LOSES ITS HEATING SOURCE.
TUESDAY APPEARS TO BE THE LAST WARM DAY IN A WHILE WITH MUCH
STRONGER COLD FRONT EXPECTED TO WORK THROUGH THE AREA LATE TUESDAY
AFTERNOON INTO TUESDAY NIGHT. MUCH OF THE MIDLEVEL FORCING IS
FOCUSED ACROSS THE NORTHERN CWA...AND WITH THE LACK OF MOISTURE AM
CONCERNED PREVIOUS FORECAST WAS OVERDOING PRECIP POTENTIAL. LEFT
LIKELY MENTION IN THE NORTHEAST...BUT OTHERWISE SCALED EVERYTHING
BACK INTO THE CHANCE CATEGORY.
MUCH COOLER PATTERN SETTING UP FOR THE REMAINDER OF THE WEEK.
BREEZY NORTHWEST WINDS ARE EXPECTED ON WEDNESDAY WITH STRONG MIXING
AND DEEP NORTHWEST FLOW. A SERIES OF UPPER WAVES ARE EXPECTED TO
MOVE THROUGH THE AREA ON THURSDAY THROUGH SATURDAY...BUT WITH LACK
OF AVAILABLE MOISTURE SCALED BACK INHERITED POPS.
&&
.AVIATION.../FOR THE 12Z TAF ISSUANCE/
VFR CONDITIONS WILL PREVAIL THROUGH 12Z TUESDAY. ISOLATED
THUNDERSTORMS MAY DEVELOP WEST OF I29 AND ALSO SOUTH OF INTERSTATE
90 THROUGH THE EVENING HOURS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
$$
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1207 PM EDT MON SEP 3 2012
.SYNOPSIS...
THE REMNANTS OF ISAAC WILL CONTINUE TO IMPACT THE REGION TODAY
THROUGH WEDNESDAY WITH DEEP TROPICAL MOISTURE AND DAILY WIDESPREAD
SHOWERS AND THUNDERSTORMS WITH LOCALLY HEAVY RAIN. DRIER AIR WILL
FINALLY PUSH INTO THE AREA BY FRIDAY AS A SERIES OF COLD FRONTS
DROP SOUTHEAST INTO THE REGION.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1200 PM EDT MONDAY...
HAVE ISSUED A FLASH FLOOD WATCH FOR THE AREA ROUGHLY ALONG THE
FOOTHILLS OF NC...NORTHEAST ALONG THE LEE OF THE BLUE RIDGE TO THE
ROANOKE...AND THEN EASTWARD INTO AREAS ALONG AND NEAR VA ROUTE
460. POCKETS OF THIS REGION HAVE BEEN HARDEST HIT OVER THE WEEKEND
WITH LOCALLY HEAVY RAIN FROM THUNDERSTROMS. AS SUCH...FLASH FLOOD
GUIDANCE VALUES ARE THE LOWER HERE. STORMS WITH VERY HEAVY
RAINFALL RATES ARE EXPECTED AGAIN THIS AFTERNOON AND EVENING.
LOCALIZED FLASH FLOODING MAY OCCUR WITH THESE STORMS.
AS OF 1002 AM EDT MONDAY...
EARLY MORNING PATCHY FOG HAS DISSIPATED IN MOST AREA. JUST A FEW
SMALL POCKETS REMAIN...HOWEVER THESE TOO WILL ERODE BY NOON.
PRECIPITATION ACROSS THE AREA IS MINIMAL. KFCX 88D SHOWING SOME
ISOLATED SHOWERS NEAR AND EAST OF LYNCHBURG VA...AND ALSO A FEW
MAKING THEIR WAY INTO THE NORTHERN MOUNTAINS OF NORTH CAROLINA
FROM NORTHEAST TENNESSEE. THE EXPECTATION IS FOR THIS TO BE THE
NORM THROUGH AROUND NOON. STARTING IN THE EARLY
AFTERNOON...DAYTIME HEATING WILL YIELD ANOTHER RAPID DEVELOPMENT
AND GENEROUS COVERAGE OF SHOWERS AND STORMS ACROSS THE REGION.
HAVE TWEAKED POP AND WEATHER GRIDS TO REFLECT THIS LATEST
EXPECTATION. ALSO HAVE TWEAKED HOURLY TEMPERATURE...DEW
POINT...SKY COVER AND WINDS TO REFLECT THE LATEST OBSERVATIONS AND
EXPECTED TRENDS INTO THE EARLY AFTERNOON.
AS OF 450 AM EDT MONDAY...
WATER VAPOR LOOP SHOWED UPPER LOW OVER EXTREME SOUTHWEST OHIO. AT
THE SURFACE...THE 08Z MSAS ANALYSIS HAD THE LOW OVER THE
KENTUCKY/ILLINOIS/INDIANA BORDER. ALL MODELS OPEN UP THE UPPER LOW
DURING THE NEXT 24 HOURS. SUSPECT EVEN THE SHORT RANGE GUIDANCE
MAY BE A LITTLE ON THE SLOW SIDE WITH THE EVOLUTION OF THE UPPER
SYSTEM...SINCE AN MCS OVER MISSISSIPPI AND ALABAMA MAY HAVE
ALREADY BROKEN OFF A PIECE OF VORTICITY FROM THE MAIN UPPER LOW.
THE MAIN NORTHERN PART OF THE UPPER SYSTEM IS FORECAST TO TRACK
TOWARD PENNSYLVANIA AND THE NORTHERN JET STREAM.
REGIONAL RADARS INDICATED WIDESPREAD SHOWERS AROUND THE UPPER LOW.
MODELS HAVE THIS PRECIPITATION EDGING SLOWLY EAST THIS MORNING. SO
THROUGH NOON HAVE THE HIGHER PROBABILITY OF PRECIPITATION IN THE
FAR WESTERN COUNTY WARNING AREA. EXPECT COVERAGE TO JUST BE
ISOLATED THROUGH MID MORNING FOR THE REST OF THE FORECAST AREA.
WIDESPREAD PRECIPITATION IS EXPECTED THIS AFTERNOON AND EVENING.
SREF AND LOCAL WRF ALONG WITH OTHER GUIDANCE WAS FOCUSING BEST
THREAT OF HEAVY RAIN ALONG THE SOUTHERN BLUE RIDGE...ESPECIALLY IN
THE NORTHWEST NORTH CAROLINA MOUNTAINS. GIVEN THE AIR MAS IS STILL
VERY TROPICAL WITH PRECIPITABLE WATER VALUES IN THE 1.5 TO 2.2
INCH RANGE HAVE LOCALLY HEAVY RAIN MENTIONED FOR ALL PARTS OF THE
FORECAST AREA THIS AFTERNOON AND EVENING.
FFG IS LOWEST IN THE NEW RIVER VALLEY AND ALONG THE FOOTHILLS OF
THE BLUE RIDGE FROM PATRICK AND HENRY COUNTIES DOWN TO WILKES AND
YADKIN COUNTIES. WILL CONTINUE TO ASSESS ANY FLASH FLOOD THREAT
DURING THE MORNING.
ANTICIPATE MINIMAL CHANGE IN TEMPERATURES FROM PAST FEW DAYS.
STAYED CLOSE TO PERSISTENCE FOR MAXIMUM TEMPERATURES TODAY AND
LOWS TONIGHT...WHICH ENDS UP BEING ON THE WARM SIDE OF GUIDANCE.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 254 AM EDT MONDAY...
REMNANTS OF ISAAC UPPER LEVEL TROUGH OPENS ON TUESDAY AND SLOWLY
MOVES OVER THE REGION TUESDAY AND WEDNESDAY. THE TROUGH WILL KEEP
BULK OF THE RAIN OVER THE MOUNTAINS TUESDAY AFTERNOON THEN ALONG THE
BLUE RIDGE AND FOOTHILL COUNTIES TUESDAY EVENING. TUESDAY LOOKS TO
BE THE BETTER DAY FOR SEVERE WEATHER WITH A LOW LEVEL JET CROSSING
THE REGION. CAN NOT RULE OUT STRONG TO SEVERE STORMS WITH A FEW
SUPERCELLS TRACKING ACROSS THE AREA. MOVEMENT OF THESE STORMS WILL
BE RELATIVELY SLOW AND AROUND 20-30 MPH. STRONG TO SEVERE STORMS
WILL BE HIGHLY DEPENDENT ON HEATING THROUGH THE DAY.
THE UPPER LEVEL TROUGH WILL MOVE TO THE BLUE RIDGE WEDNESDAY WITH A
LINE OF SHOWERS STARTING NEAR THE BLUE RIDGE IN THE
AFTERNOON...MOVING EAST INTO THE PIEDMONT IN THE EVENING. STRONG TO
SEVERE STORMS ARE POSSIBLE BUT THE BIGGER THREAT WILL BE EAST OF THE
AREA AND ACROSS THE COASTAL PIEDMONT OF THE MID ATLANTIC REGION.
WEAK HIGH PRESSURE BUILDS IN WEDNESDAY...PUSHING THE TROPICAL AIR MASS
OFF TO THE EAST.
AFTERNOON TEMPERATURES WILL BE NEAR NORMAL TUESDAY AND WEDNESDAY
WHILE OVERNIGHTS CONTINUE TO BE MUGGY AND ABOVE NORMAL.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 1230 PM EDT SUNDAY...
DEEP TROPICAL MOISTURE ASSOCIATED WITH THE REMNANT OF ISAAC WILL
FINALLY GET BOOTED SE DURING THURSDAY AHEAD OF AN INITIAL WEAK COLD
FRONT THAT WILL DROPPING SE IN ADVANCE OF A DEVELOPING ERN 5H TROF.
HOWEVER STILL ENOUGH LIFT WITH THE RESIDUAL SHEAR AXIS AND WEAK
SURFACE TROF TO PROMPT ADDITIONAL SHRA WED NIGHT WITH PERHAPS YET
ANOTHER ORGANIZED BAND ESPCLY EAST ON THURSDAY. THUS KEPT IN HIGH
CHANCE POPS INTO THURSDAY WHICH MAY NEED TO GO HIGHER IN LATER
UPDATES. BOUNDARY MAY TEND TO EDGE SOUTH OF THE AREA DURING FRIDAY
BEFORE THE FLOW STARTS TO BACK AGAIN AHEAD OF A MORE POTENT WAVE
ROUNDING THRU THE GREAT LAKES COLD POOL SAT.
THIS FEATURE SHOULD PUSH A STRONGER SECONDARY COLD FRONT TOWARD
THE APPALACHIANS SAT NIGHT INTO SUNDAY WITH A ANOTHER ROUND OF
SHRA/TSRA AS DEEPER MOISTURE MAKES A QUICK RETURN. JUST HOW FAST
THE FRONT MOVES EAST IFFY GIVEN HINT OF A 5H CUTOFF DEVELOPING
OVER THE OHIO VALLEY BY SUNDAY SO FOLLOWING A BIT OF A BLEND GIVEN
UNCERTAINTY NEXT WEEKEND.
OTRW APPEARS ENOUGH DRYING TO BASICALLY CUT POPS LATER THU NIGHT
THRU FRIDAY NIGHT...THEN RETURNING TO CHANCE COVERAGE FROM WEST TO
EAST LATER SATURDAY THRU SUNDAY. TEMPS TO REMAIN WARM/MUGGY THU
WITH HIGHS MOSTLY IN THE 80S INTO FRIDAY ALTHOUGH A BIT LESS
HUMID. MAY SEE THINGS COOL OFF SOME WITH SHRA SAT BUT MORE SO
SUNDAY PENDING THE FRONTAL TIMING WITH HIGHS LOW/MID 70S WEST AND
LOW 80S EAST.
&&
.AVIATION /16Z MONDAY THROUGH FRIDAY/...
AS OF 740 AM EDT MONDAY...
MID LEVEL CLOUDS WILL LIMIT THE EXTENT OF FOG THIS MORNING...BUT
STRATUS WITH IFR CEILINGS DEVELOPED OVERNIGHT ACROSS THE REGION.
EXPECT CEILINGS TO LIFT TO MVFR BY 15Z/11AM THEN VFR BY 17Z/1PM.
HAVE USED THE LOCAL WRF AND HRRR FOR TIMING OF WHEN THUNDERSTORMS
WILL DEVELOP THIS AFTERNOON. THESE MODELS HAVE STORMS INITIALLY DEVELOPING
BETWEEN 19Z/3PM AND 21Z/5PM. NUMEROUS THUNDERSTORMS WILL CONTINUE
INTO THE EVENING...THEN COVERAGE WILL DIMINISH AFTER 00Z/8PM. VERY
HEAVY RAIN IS LIKELY WITH ANY OF THE STRONGER STORMS WHICH WILL
RESULT IN MVFR TO IFR VISIBILITIES.
TROPICAL PATTERN WILL CONTINUE THROUGH THURSDAY WITH THE REMNANTS
OF ISAAC SLOWLY APPROACHING THE AREA. ANTICIPATE PRIMARILY VFR
CONDITIONS WITH BRIEF IFR/MVFR CONDITIONS UNDER ANY STRONGER
SHOWERS OR STORMS. LATE NIGHT AND EARLY MORNING IFR/MVFR MOUNTAIN
AND RIVER VALLEY FOG IS ALSO EXPECTED.
BY THURSDAY NIGHT INTO EARLY FRIDAY...A COLD FRONT WILL SWEEP
THROUGH THE AREA WITH A SURGE OF DRIER AIR BEHIND IT BY FRIDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...FLASH FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR VAZ013-014-
016-017-022-032>035-043-045>047.
NC...FLASH FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR NCZ003>005-
019-020.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/DS
SHORT TERM...RCS
LONG TERM...JH
AVIATION...AMS/KM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
256 PM CDT MON SEP 3 2012
.SHORT TERM...TONIGHT THROUGH THURSDAY
256 PM CDT MON SEP 3 2012
MAIN FORECAST CONCERNS ARE ON PRECIPITATION CHANCES THROUGH
WEDNESDAY.
CURRENTLY AS OF 20Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED BROAD TROUGHING OVER SOUTHWEST AND SOUTH CENTRAL CANADA...
WITH NEARLY ZONAL FLOW ON ITS SOUTH SIDE ACROSS MUCH OF THE NORTHERN
U.S.. WITHIN THE BROAD UPPER TROUGHING...A PORTENT SHORTWAVE IS
EVIDENT OVER CENTRAL ALBERTA. IN THE ZONAL FLOW...THERE ARE NUMEROUS
WEAK SHORTWAVES...WHICH DURING THIS MORNING PRETTY MUCH ALL HAD AT
LEAST ACCAS OR CONVECTION WITH THEM: ONE IN NORTH DAKOTA...ANOTHER
IN WESTERN MINNESOTA...ONE IN WESTERN NEBRASKA AND LASTLY ONE IN
CENTRAL IOWA. DPVA AHEAD OF THE SHORTWAVE IN CENTRAL IOWA COMBINED
WITH A WEAKENING SURFACE COLD FRONT EXTENDING FROM CENTRAL UPPER
MICHIGAN TO NEAR DES MOINES...AS WELL AS MLCAPE VALUES THAT HAVE
CLIMBED TO 1500-2000 J/KG WITH LITTLE CIN PER RAP ANALYSIS...HAS
ALLOWED FOR SHOWER AND THUNDERSTORM DEVELOPMENT. MOST OF THE
ACTIVITY HAS BEEN DISORGANIZED...DUE TO 0-6KM SHEAR BELOW 30 KT
WHERE STORMS ARE IN THE FORECAST AREA. ALSO...A SURGE OF MONSOONAL
MID-CLOUDS THROUGH THE UPPER FLOW IS HELPING TO PUT A LID ON THE
AMOUNT OF INSTABILITY. THERE ARE EVEN SOME SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS COMING OUT OF THESE MID CLOUDS. WITH THE
VARYING CLOUD COVER AND PRECIPITATION...TEMPERATURES TODAY ARE ALL
OVER THE PLACE IN THE FORECAST AREA. MOST LOCATIONS REACHED
80...WHILE BOSCOBEL GOT CLOSE TO 90. ABNORMALLY HIGH DEWPOINTS
PERSIST TOO...WITH MOST OF THE AREA SEEING READINGS AROUND 70F.
TONIGHT AND TUESDAY...VERY TRICKY FORECAST TO SAY THE LEAST. THE
NEAR ZONAL FLOW WILL PERSIST THROUGH THIS PERIOD AS THE POTENT
ALBERT SHORTWAVE DIGS DOWN INTO THE NORTHERN PLAINS. MODELS CONTINUE
TO INDICATE WEAK SHORTWAVES MOVING THROUGH THIS FLOW...LIKE THOSE
AROUND THE DAKOTAS TODAY. WITH MUCAPE VALUES PROGGED TO NOT DROP
MUCH BELOW 1000 J/KG...HIGHLY CONCERNED THERE COULD BE OFF AND ON
SHOWERS AND THUNDERSTORMS THROUGHOUT THIS PERIOD. THIS HAS BEEN
SUGGESTED THE PAST FEW DAYS...ESPECIALLY BY THE ECMWF...THOUGH THE
LATEST 03.12Z ECMWF IS NOT AS ACTIVE. NOW SOME HI RESOLUTION MODEL
RUNS HAVE SUGGESTED THAT THE CURRENT AFTERNOON CONVECTION DROPS
SOUTHEAST THIS EVENING...WHILE OTHER CONVECTION DEVELOPS IN IOWA AND
DROPS SOUTHEAST. THIS ALLOWS THE FORECAST AREA TO END UP DRY AFTER
MIDNIGHT. FOR NOW HOLDING ON TO SOME LOW CHANCES OF PRECIPITATION
BECAUSE OF TOO MUCH UNCERTAINTY TO GO DRY BASED ON THE ENVIRONMENT.
IF SKIES CLEAR OUT TONIGHT...THE HIGH AMOUNT OF SURFACE MOISTURE
AROUND AND WEAK WIND FIELD WOULD LIKELY RESULT IN WIDESPREAD
RADIATION FOG. NOT ENTIRELY CONFIDENT WE WILL HAVE A LONG PERIOD OF
CLEAR SKIES...THOUGH. SO IN SUMMARY...THERE APPEARS TO BE TWO
SCENARIOS FOR TONIGHT:
1. SKIES CLEAR AND WE END UP WITH DENSE FOG
2. PERIODS OF ACCAS AND ISOLATED SHOWERS/STORMS
RIGHT NOW...BANKING ON NUMBER 2 AND ACKNOWLEDGING THE FOG BY ADDING
AT LEAST A PATCHY MENTION AFTER MIDNIGHT INTO TUESDAY MORNING. WITH
THE HIGH AMOUNT OF SURFACE MOISTURE...ANTICIPATING TEMPERATURES
OUTSIDE OF THE TYPICAL COLD SPOTS TO NOT DROP BELOW THE MID 60S.
DEPENDING ON AMOUNT OF SUN ON TUESDAY...WITH 850MB TEMPS BETWEEN
18-20C...HIGHS COULD GET CLOSE TO 90.
TUESDAY NIGHT AND WEDNESDAY...THE POTENT SHORTWAVE TROUGH COMING
INTO THE NORTHERN PLAINS AT 00Z WEDNESDAY IS FORECAST TO DIG INTO
MINNESOTA BY 12Z...THEN RAPIDLY SHOOT EAST OVER MUCH OF MICHIGAN BY
00Z THURSDAY. THIS RAPID MOVEMENT MEANS AN OVERALL SHORT TIME WINDOW
FOR PRECIPITATION FORCED BY THE TROUGH. NOTE THAT THE BEST 500-300MB
PV ADVECTION IS STILL SUGGESTED TO STAY TO THE NORTH OF THE FORECAST
AREA. HOWEVER...THE COMBINATION OF WEAK 500MB HEIGHT FALLS...A SURGE
OF LOW TO MID LEVEL MOISTURE TRANSPORT...AS WELL AS AT LEAST
1000-1500 J/KG OF MUCAPE ACCOMPANYING THE MOISTURE TRANSPORT SHOULD
PRODUCE SHOWERS AND THUNDERSTORMS ACROSS MUCH OF THE AREA. SOME OF
THESE COULD GET GOING AS EARLY AS THE EVENING...BUT BETTER CHANCES
ARE EXPECTED AFTER MIDNIGHT THROUGH ABOUT 15Z WEDNESDAY...WHEN THE
TROUGH IS HAVING ITS BIGGEST FORCING INFLUENCE. 1-6KM SHEAR IS
GENERALLY 15-25KT...WHICH SHOULD KEEP CONVECTION SUB-SEVERE. AFTER
15Z...STRONG SUBSIDENCE WILL WORK IN WEST TO EAST...CLEARING SKIES
OUT. WINDS SHOULD PICK UP TOO AS THE PRESSURE GRADIENT TIGHTENS...
COLD ADVECTION AND DEEP MIXING OCCUR. NOTING ABOUT THE COLD
ADVECTION...850MB TEMPS WHICH LOOK TO HOVER BETWEEN 16-20C TUESDAY
NIGHT END UP FALLING TO 12-14C OR SLIGHTLY COOLER BY 00Z WEDNESDAY.
THUS...EXPECT COOLER HIGHS FOR WEDNESDAY ON THE ORDER OF MID 70S TO
LOWER 80S. TUESDAY NIGHT WILL STILL BE WARM WITH LOWS IN THE
60S...THANKS TO SOUTH FLOW AHEAD OF THE SHORTWAVE/ASSOCIATED COLD
FRONT AND HIGHER DEWPOINTS.
WEDNESDAY NIGHT AND THURSDAY...IN THE WAKE OF WEDNESDAYS POTENT
SHORTWAVE...UPPER FLOW TURNS ZONAL OVER THE AREA. BUT THIS IS
BRIEF...WITH ATTENTION TURNING BACK TO ALBERTA WHERE YET ANOTHER
POTENT SHORTWAVE IS PROGGED TO DROP SOUTH INTO MONTANA BY 00Z
FRIDAY. WEDNESDAY NIGHT STILL LOOKS DRY THANKS TO LINGERING DRY AIR
AND SUBSIDENCE IN THE WAKE OF WEDNESDAYS TROUGH. THURSDAY IS A
LITTLE MORE PROBLEMATIC. TO THE NORTH...MODELS ARE INDICATING A
COUPLE OF SHORTWAVES CROSSING NORTHERN MINNESOTA AND WISCONSIN...
WHICH BRING DOWN A COLD FRONT INTO NORTHWEST WI BY 00Z. BOTH THE
03.12Z NAM AND 03.06Z GFS DEPICT SOME LIGHT QPF ACROSS TAYLOR COUNTY
WITH THIS FEATURE IN THE AFTERNOON. SOUNDINGS SUGGEST VERY LITTLE
MUCAPE WITH THIS FRONT AND A FAIRLY DRY BOUNDARY LAYER BELOW 750MB.
NEW 03.12Z GFS HAS CAME IN DRY. THEREFORE...HAVE HELD OFF ON MENTION
ANY PRECIPITATION CHANCES UP AROUND TAYLOR COUNTY. FOR THE REST OF
THE AREA...300-305K ISENTROPIC LIFT GRADUALLY INCREASES DURING THE
AFTERNOON...ALL KIND OF DOWNSTREAM OF THAT SHORTWAVE DROPPING INTO
MONTANA. SHOULD SEE SOME MID/HIGH CLOUDS DEVELOP AS A RESULT OF THIS
LIFT...BUT THINKING THE MAJORITY OF THESE CLOUDS ANY PRECIPITATION
POTENTIAL WITH THEM WILL STAY WEST/SOUTHWEST OF THE AREA. THIS
AGREES WELL WITH THE 03.12Z GFS/ECMWF. COOLER PERIOD ANTICIPATED.
MAY HAVE TO WATCH FOR VALLEY FOG POTENTIAL IF THE SURFACE RIDGE OF
HIGH PRESSURE COMING IN WEDNESDAY NIGHT BUILDS IN FASTER.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
256 PM CDT MON SEP 3 2012
THROUGH SATURDAY...MODELS REMAIN IN GOOD AGREEMENT WITH THE HANDLING
OF THE POTENT SHORTWAVE OVER MONTANA...HOW IT ENDS UP FORMING A
FAIRLY DEEP TROUGH OVER THE UPPER AND MID MISSISSIPPI RIVER VALLEYS
BY 12Z SATURDAY. AS THIS TROUGH FORMS...FRONTOGENESIS DOWNSTREAM
WILL LIKELY SPREAD MID/HIGH CLOUDS ACROSS THE AREA THURSDAY NIGHT
AND FRIDAY...SOME OF WHICH COULD PRODUCE A FEW SHOWERS. OVERALL...
BULK OF PRECIPITATION IS ANTICIPATED TO STAY TO THE SOUTH...CLOSER
TO A DEVELOPING LOW PRESSURE SYSTEM LIFTING OUT OF THE CENTRAL
PLAINS. BY FRIDAY NIGHT...AS THE TROUGHING MOVES IN...THE CLOUDS AND
POTENTIAL FOR SHOWERS GET PUSHED EAST. HIGH PRESSURE THEN BUILDS IN
FOR SATURDAY. MUCH OF THIS PERIOD THROUGH SATURDAY WILL BE BELOW
NORMAL...DUE TO FIRST CLOUDS ON FRIDAY AND THEN 850MB TEMPS FALLING
TO 6-8C FOR SATURDAY. HIGHS MAY STRUGGLE TO CLIMB TO OR MUCH ABOVE
70.
BEYOND SATURDAY...MODELS HANDLE THE TROUGHING DIFFERENTLY...WITH THE
03.12Z ECMWF AND CANADIAN CLOSING IT OFF AND PERHAPS MOVING IT
SOUTHEAST...WHEREAS THE 03.12Z GFS AND ITS ENSEMBLES REMAIN MORE
PROGRESSIVE. FOR THE FORECAST AREA...EITHER SCENARIO DOESNT MATTER
MUCH...AS ALL MODELS END UP HAVING UPPER RIDGING BUILDING UP OVER
THE PLAINS AND INTO THE FORECAST AREA LATE MONDAY. THIS WILL KEEP
CONDITIONS DRY WITH A GRADUAL WARMING TREND. BY MONDAY...850MB TEMPS
ARE BACK UP TO 12-14C...YIELDING HIGHS AT LEAST AROUND NORMAL.
&&
.AVIATION...THIS AFTERNOON INTO TUESDAY
1215 PM CDT MON SEP 3 2012
BKN LINE OF CONVECTION WAS MOVING STEADILY EAST/NORTHEAST ACROSS THE
FCST AREA AT MID-DAY. LINE HAD ALREADY CLEARED KRST WHILE DISTANCE
SPEED-TOOL PUTS IT THRU THE KLSE AREA IN THE 1830-1930Z TIME FRAME.
ADDED A TEMPO MVFR TSRA PERIOD TO KLSE FOR THE EARLY AFTERNOON.
CONDITIONS GO BACK TO VFR AFTER THE LINE OF SHRA/TSRA PASSES FOR
THE LATE AFTERNOON/EVENING HOURS. HOWEVER...THE MOIST AIRMASS WITH
SOME MIXED LAYER OR ELEVATED CAPE REMAINS OVER THE AREA TONIGHT INTO
TUE. WITH WEAK SHORTWAVES RIPPLING ACROSS THE AREA TONIGHT INTO
TUE...ISOLATED TO SCT SHRA/TSRA REMAIN POSSIBLE. GIVEN POOR
CONFIDENCE IN THE TIMING/COVERAGE DETAILS OF ANY CONVECTION TONIGHT
INTO TUE...LEFT THIS MENTION OUT OF THE TAFS FOR NOW VS. HAVING A
RATHER LONG PERIOD OF VCSH AT BOTH SITES. LATER TAF ISSUANCES CAN
ADD ANY SHRA/TSRA TO TAFS FOR SHORTER PERIODS OF TIME IF NEEDED AS
DETAILS BECOME CLEARER.
THE OTHER CONCERN IS THE MOIST LOW LEVEL/BOUNDARY LAYER AIRMASS THAT
WILL REMAIN OVER THE AREA TONIGHT. TEMP-DEWPOINT SPREADS ARE LIKELY
TO BE LOW GOING INTO SUNSET...ALONG WITH LIGHT/VARIABLE SFC WINDS.
IF SKIES TREND TOWARD MORE CLEAR/MOSTLY CLEAR TONIGHT VS. BKN MID/
HIGH CLOUD DECKS...MVFR/IFR BR/FG WILL BE MORE OF A PROBLEM AFTER
MIDNIGHT INTO THE MID MORNING HOURS OF TUE. WITH THE POTENTIAL FOR
SCT -SHRA TONIGHT AND BKN MID/HIGH CLOUDS LOOKING MORE FAVORED...
ONLY ADDED 4SM BR IN THE 08-14Z TIME TO BOTH KRST/KLSE FOR NOW.
LATER SHIFTS WILL HAVE TO WATCH THIS FOR IFR FG POTENTIAL AS WELL.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
256 PM CDT MON SEP 3 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RRS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1215 PM CDT MON SEP 3 2012
.SHORT TERM...TODAY THROUGH WEDNESDAY
327 AM CDT MON SEP 3 2012
CONCERNS CENTER AROUND RAIN CHANCES THROUGH THE PERIOD/SEVERE
CHANCES TODAY.
BUSY WATER VAPOR LOOP THIS MORNING WITH A MID LEVEL TROUGH MOVING
THROUGH MN AND THEN A MORE VIGOROUS CLOSED LOW/TROUGH MOVING THROUGH
ALBERTA CANADA/MONTANA. AT THE SURFACE...A COLD FRONT EXTENDED FROM
NEAR INTERNATIONAL FALLS TO SAINT CLOUD MN...AND THEN SOUTHWESTWARD
TO SIOUX FALLS SD. RADAR MOSAIC SHOWING BAND OF SCATTERED
SHOWERS/THUNDERSTORMS AHEAD OF THE FRONT FROM NEAR THE ARROWHEAD OF MN
INTO NORTHWEST WI AND EAST CENTRAL MN. RAP SHOWS THIS ACTIVITY WAS
ON THE EASTERN PERIPHERY OF FAIRLY DECENT AXIS OF 850MB MOISTURE
TRANSPORT. OTHERWISE...TEMPERATURES ACROSS THE FORECAST AREA AT 3 AM
WERE HOLDING IN THE UPPER 60S/LOWER 70S WITH DEWPOINTS IN THE MIDDLE
60S.
SUNDAY EVENING MODEL RUNS SHOWING FAIRLY DECENT AGREEMENT THROUGH
THE SHORT TERM PERIOD.
LOOK FOR THE MID-LEVEL SHORTWAVE AND ASSOCIATED SURFACE COLD FRONT
OVER MN TO SINK SLOWLY SOUTHEAST INTO THE AREA TODAY...WHILE
UNDERGOING SOME WEAKENING. RAP/NAM MODELS SHOWING BEST 850MB
MOISTURE TRANSPORT AHEAD OF THE TROUGH/FRONT PUSHING EAST OF THE
AREA BY LATER THIS MORNING. HOWEVER...MODELS FAIRLY PERSISTENT IN
PRODUCING SCATTERED SHOWERS AND THUNDERSTORM TODAY ACROSS THE
AREA...WITH BETTER CHANCES HEADED INTO THE AFTERNOON GIVEN PEAK
HEATING/HIGHER DEW POINT POOLING AND 0-3KM MUCAPE PEAKING IN THE
3000-5000J/KG RANGE WITH DOWNDRAFT CAPE IN THE 1500-2000J/KG RANGE.
UPPER LEVEL DYNAMICS HELP ALSO GIVEN RIGHT ENTRANCE REGION OF 300MB
JET PER THE NAM BY THIS AFTERNOON. MODEL SOUNDINGS SHOW INVERTED-V
AND ALTHOUGH 0-3KM BULK SHEAR FAIRLY LIMITED...DOWNDRAFT CAPE HAS ME
A BIT CONCERNED FOR DAMAGING WIND POTENTIAL. WILL HAVE TO KEEP A
VERY CLOSE EYE ON THINGS TODAY. OTHERWISE...ANOTHER UNSEASONABLY
WARM DAY ON TAP WITH HIGHS PUSHING INTO THE 80S ONCE AGAIN.
LOOKING FOR THE BULK OF THE SHOWERS/THUNDERSTORMS TO MOVE SOUTHEAST
OF THE AREA THIS EVENING...BUT THEN MODELS SHOWING ANOTHER MID-LEVEL
TROUGH PUSHING ACROSS THE PLAINS TOWARD THE AREA AFTER MIDNIGHT WITH
WEAK ISENTROPIC LIFT AND MOISTURE TRANSPORT. KEPT SMALLER 20-30 POP
SHRA/T CHANCE TO COVER THIS WEAKER SIGNAL.
GFS AND NAM HINTING AT SOME SORT OF WEAK TROUGH RIPPLING THROUGH
FAIRLY HIGH-ZONAL FLOW ALOFT ON TUESDAY WITH SOME MINOR TIMING
DIFFERENCES NOTED. GIVEN THIS RATHER NONDESCRIPT SIGNAL...WILL STICK
WITH SLIGHT CHANCE OF SHRA/TS.
A MORE VIGOROUS MID-LEVEL CLOSED LOW SWINGS EAST ACROSS SOUTHERN
CANADA TUESDAY NIGHT/WEDNESDAY WITH TROUGH AXIS AND ASSOCIATED
STRONG SURFACE COLD FRONT SWINGING EAST ACROSS THE AREA. THIS HAS BEEN A
RATHER CONSISTENT SIGNAL THE LAST FEW DAYS NOW...SO FEEL COMFORTABLE
WITH HIGHER-END CHANCE TO LIKELY SHRA/TS. GIVEN TIMING OF THE
FRONTAL PASSAGE THROUGH THE AREA WEDNESDAY MORNING...SEVERE THREAT
LOOKS TO BE SOUTHEAST OF THE AREA DURING THE AFTERNOON.
OTHERWISE...MODEL SOUNDINGS SHOWING GOOD MIXING/DRYING BEHIND THE
FRONT WEDNESDAY AFTERNOON ON BREEZY NORTHWEST WINDS IN THE 15 TO 30
MPH RANGE. TEMPERATURES WILL ALSO RETURN TO NEAR SEASONAL NORMALS IN
THE MID 70S TO LOWER 80S.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
327 AM CDT MON SEP 3 2012
FAIRLY GOOD AGREEMENT BETWEEN THE GFS AND ECMWF IN THE WEDNESDAY
NIGHT THROUGH SATURDAY TIME FRAME. WEDNESDAY NIGHT/THURSDAY LOOK
COOLER AND DRY AS MID/UPPER LEVEL TROUGH SETTLES INTO THE AREA. LOWS
WEDNESDAY NIGHT EXPECTED TO FALL INTO THE UPPER 40S TO LOWER 50S WITH
HIGHS ON THURSDAY IN THE 70S. SHRA/TS CHANCES RETURN TO THE AREA
THURSDAY NIGHT THROUGH FRIDAY NIGHT AS AS ANOTHER MID-LEVEL TROUGH
DROPS THROUGH THE REGION WITH A REINFORCING SHOT OF COOLER AND MORE
AUTUMN-LIKE AIR. EXPECTING HIGHS ON FRIDAY IN THE UPPER 60S TO
MIDDLE 70S WITH LOWS IN THE UPPER 40S TO MIDDLE 50S. SATURDAY
CONTINUES TO BE COOL BUT DRY WITH HIGHS IN THE UPPER 60S AND LOWER
70S AFTER OVERNIGHT LOWS IN THE UPPER 40S TO LOWER 50S. APPEARS
SUNDAY WILL SEE SOME WARMING AS MID-LEVEL HEIGHTS BUILD IN RESPONSE
TO RIDGE BUILDING IN FROM THE PLAINS. LOOK FOR HIGHS IN THE LOWER TO
MIDDLE 70S.
&&
.AVIATION...THIS AFTERNOON INTO TUESDAY
1215 PM CDT MON SEP 3 2012
BKN LINE OF CONVECTION WAS MOVING STEADILY EAST/NORTHEAST ACROSS THE
FCST AREA AT MID-DAY. LINE HAD ALREADY CLEARED KRST WHILE DISTANCE
SPEED-TOOL PUTS IT THRU THE KLSE AREA IN THE 1830-1930Z TIME FRAME.
ADDED A TEMPO MVFR TSRA PERIOD TO KLSE FOR THE EARLY AFTERNOON.
CONDITIONS GO BACK TO VFR AFTER THE LINE OF SHRA/TSRA PASSES FOR
THE LATE AFTERNOON/EVENING HOURS. HOWEVER...THE MOIST AIRMASS WITH
SOME MIXED LAYER OR ELEVATED CAPE REMAINS OVER THE AREA TONIGHT INTO
TUE. WITH WEAK SHORTWAVES RIPPLING ACROSS THE AREA TONIGHT INTO
TUE...ISOLATED TO SCT SHRA/TSRA REMAIN POSSIBLE. GIVEN POOR
CONFIDENCE IN THE TIMING/COVERAGE DETAILS OF ANY CONVECTION TONIGHT
INTO TUE...LEFT THIS MENTION OUT OF THE TAFS FOR NOW VS. HAVING A
RATHER LONG PERIOD OF VCSH AT BOTH SITES. LATER TAF ISSUANCES CAN
ADD ANY SHRA/TSRA TO TAFS FOR SHORTER PERIODS OF TIME IF NEEDED AS
DETAILS BECOME CLEARER.
THE OTHER CONCERN IS THE MOIST LOW LEVEL/BOUNDARY LAYER AIRMASS THAT
WILL REMAIN OVER THE AREA TONIGHT. TEMP-DEWPOINT SPREADS ARE LIKELY
TO BE LOW GOING INTO SUNSET...ALONG WITH LIGHT/VARIABLE SFC WINDS.
IF SKIES TREND TOWARD MORE CLEAR/MOSTLY CLEAR TONIGHT VS. BKN MID/
HIGH CLOUD DECKS...MVFR/IFR BR/FG WILL BE MORE OF A PROBLEM AFTER
MIDNIGHT INTO THE MID MORNING HOURS OF TUE. WITH THE POTENTIAL FOR
SCT -SHRA TONIGHT AND BKN MID/HIGH CLOUDS LOOKING MORE FAVORED...
ONLY ADDED 4SM BR IN THE 08-14Z TIME TO BOTH KRST/KLSE FOR NOW.
LATER SHIFTS WILL HAVE TO WATCH THIS FOR IFR FG POTENTIAL AS WELL.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
327 AM CDT MON SEP 3 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....RRS