Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/09/12
AREA FORECAST DISCUSSION
NWS TUCSON AZ
255 PM MST FRI SEP 7 2012
.SYNOPSIS...ABUNDANT MOISTURE WILL RESULT IN MAINLY AFTERNOON AND
EVENING THUNDERSTORMS THROUGH WEDNESDAY. HEAVY RAINFALL WILL OCCUR
WITH THE STRONGER THUNDERSTORMS. THEREAFTER...A DRYING TREND IS
EXPECTED FOR THE LATTER PART OF NEXT WEEK.
&&
.DISCUSSION...SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS
ONGOING EAST AND SOUTH OF TUCSON. MEANWHILE...ISOLATED SHOWERS
OCCURRING ACROSS FAR WRN PIMA COUNTY. OPTED TO EXPAND THE TIME OF
THE FLASH FLOOD WATCH FOR ALL OF SE AZ UNTIL 10 PM MST THIS EVENING.
THE 07/18Z RUC HRRR PROGS PRECIP TO CONTINUE EAST OF TUCSON THRU
THIS EVENING. MEANWHILE...GENERALLY PRECIP-FREE CONDITIONS TO OCCUR
FROM TUCSON WWD. THUS...CONFIDENCE IS NOT HIGH REGARDING THE
FORECAST DETAIL INTO THIS EVENING. IF THE RUC HRRR SOLUTIONS IS
CLOSE TO REALITY...THE OFFICIAL FORECAST IS DEFINITELY OVERDONE
REGARDING PRECIP CHANCES THIS EVENING.
SAT-TUE...
07/12Z GFS/ECMWF WERE SIMILAR WITH MOVING UPPER LOW FROM OVER SE AZ
THIS AFTERNOON WESTWARD TO NRN BAJA CALIFORNIA BY MIDDAY SUN. UPPER
LOW IS PROGGED TO REMAIN QUASI-STATIONARY OVER NRN BAJA CALIFORNIA
MON...THEN SYSTEM IS PROGGED TO EJECT EWD ACROSS CENTRAL AZ TUE.
MOISTURE TO REMAIN SUFFICIENT FOR SCATTERED MAINLY AFTERNOON AND
EVENING SHOWERS/TSTMS THIS WEEKEND AND EARLY NEXT WEEK. SHOWERS/
TSTMS MAY BE ENHANCED PARTICULARLY TUE AS SYSTEM EJECTS EWD AND JUST
NORTH OF THE AREA. OPTED TO INCREASE POPS TUE TO REFLECT THIS NOTION.
WED-FRI...
MARKEDLY DRIER REGIME PROGGED VIA THE GFS/ECMWF WITH THE BULK OF
DEEPER MOISTURE TO MOVE EAST OF THE AREA. FOR WED...A SLIGHT CHANCE
OF AFTERNOON/EVENING SHOWERS/TSTMS MOST SECTIONS. THUR AND FRI...
A SLIGHT CHANCE OF AFTERNOON/EVENING SHOWERS/TSTMS GENERALLY EAST
AND SOUTH OF TUCSON WITH PRECIP-FREE CONDITIONS ELSEWHERE.
HIGH TEMPS SAT-WED TO AVERAGE A FEW DEGS BELOW NORMAL. NEAR NORMAL
DAYTIME TEMPS FORECAST TO OCCUR THUR-FRI.
&&
.AVIATION...SCT TO NUMEROUS TSRA/SHRA THRU THIS EVENING THEN PRECIP
DECREASING IN COVERAGE LATE TONIGHT. SCT -TSRA/-SHRA TO OCCUR
SATURDAY AFTERNOON. OTHERWISE...VFR CONDITIONS AND SURFACE WIND
MOSTLY LESS THAN 10 KTS THRU SATURDAY AFTERNOON OR 09/00Z. AVIATION
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...SCATTERED THUNDERSTORMS WILL OCCUR THROUGH TUESDAY
FOLLOWED BY A GRADUAL DECREASE IN THUNDERSTORMS DURING THE LATTER
PART OF THE UPCOMING WEEK.
&&
.CLIMATE...07/12Z KTWC TOTAL PRECIP WATER VALUE OF 1.99 INCHES IS
THE HIGHEST RECORDED VALUE FOR SEPTEMBER BASED ON UPPER AIR DATA
RECORDS SINCE 1951. THE YEARLY TIME SERIES PLOT MAY BE FOUND AT (ALL
LOWERCASE EXCEPT FOR TWC):
HTTP://WWW.CRH.NOAA.GOV/UNR/INCLUDE/PW.PHP?SID=TWC
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 10 PM MST THIS EVENING FOR AZZ501>515.
&&
$$
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AREA FORECAST DISCUSSION
NWS PHOENIX AZ
1010 AM MST FRI SEP 7 2012
.SYNOPSIS...
A VERY MOIST AND UNSTABLE MONSOON AIRMASS WILL CONTINUE TO COVER THE
REGION THROUGH EARLY NEXT WEEK...AND LEAD TO A CHANCE OF MAINLY
AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS EACH DAY.
THUNDERSTORM COVERAGE AND INTENSITY WILL VARY FROM DAY TO DAY...WITH
SOMEWHAT BETTER CHANCES EXPECTED OVER THE WEEKEND AND INTO NEXT
MONDAY. HIGH TEMPERATURES WILL REMAIN NEAR OR SLIGHTLY BELOW
SEASONAL NORMALS EACH DAY GIVEN THE HIGH MOISTURE CONTENT IN THE
ATMOSPHERE.
&&
...AREAS OF FLASH FLOODING EXPECTED IN THE PHOENIX METRO AREA...
.DISCUSSION...
WELL-DEFINED LOW PRESSURE SYSTEM ACROSS SOUTHERN AZ IS PRODUCING A
CONSIDERABLE AMOUNT OF UPWARD VERTICAL MOTION ACROSS EAST-CENTRAL
AZ. LEFTOVER CAPE FROM YESTERDAY HAS FINALLY BEEN REALIZED AND
WIDESPREAD SHOWERS AND THUNDERSTORMS ERUPTED ACROSS EASTERN GILA
COUNTY EARLY THIS MORNING. LATEST PSR SOUNDING CAME IN WITH 2.1
INCHES OF PRECIPITABLE WATER AND THE FOCUS REMAINS ON HEAVY
RAIN/FLOODING.
NORTHEASTERLY FLOW HAS STRENGTHENED BETWEEN THE VORT MAX TO THE
SOUTH AND HIGH PRESSURE NEAR SAN DIEGO...WHICH HAS HELPED TO STEER
THE ACTIVITY INTO THE PHOENIX METRO AREA. RAINFALL RATES HAVE BEEN
EXTREMELY HIGH SO FAR ACROSS EAST MESA...GILBERT AND CHANDLER...AND
ADDITIONAL FLOODING IS ANTICIPATED ACROSS PORTIONS OF THE VALLEY
THIS AFTERNOON. HIGHEST RAINFALL TOTALS SO FAR HAVE BEEN 2.40 INCHES
AT SAGUARO LAKE AND 2.36 INCHES IN MESA.
ADJUSTMENTS TO THE FORECAST WERE ALREADY MADE THIS MORNING TO
INCREASE POP/QPF/SKY. ADDITIONAL UPDATES TO LOWER TEMPERATURES ARE
FORTHCOMING.
&&
.PREVIOUS DISCUSSION...
THE WEEKEND LOOKS TO BE PARTICULARLY ACTIVE AND THE MODELS HAVE BEEN
HINTING AT THIS FOR THE PAST FEW DAYS. A FEW 700-300MB INVERTED
TROUGHS ARE EXPECTED TO MOVE THROUGH THE REGION THIS WEEKEND...AND
SHOULD INTERACT WITH A LARGER MORE WELL DEFINED 200-300MB PVD
/PRESENTLY OVER BAJA CALIFORNIA/. INTERESTINGLY ENOUGH...THE USUALLY
ACTIVE PORTIONS NORTH AND EAST OF PHOENIX MAY SEE A BIT OF A BREAK
AT TIMES THIS WEEKEND AS THE GREATEST MOISTURE AND INSTABILITY
ORIENT INTO A LAS VEGAS TO NOGALES AXIS. ALL GUIDANCE PRETTY MUCH
AGREES THAT SOUTHERN GILA COUNTY MAY SEE LITTLE TO NO INSTABILITY
SATURDAY AND SUNDAY. NOT SAYING THESE AREAS WILL BE DRY
ALTOGETHER...BUT I REFINED THE POPS TO BETTER REFLECT THE AXIS OF
MOISTURE/INSTABILITY. POPS WERE INCREASED ACROSS THE PHOENIX METRO
AS WELL BUT AS USUAL...THERE IS JUST ENOUGH UNCERTAINTY IN THE
GUIDANCE TO PRECLUDE ME FROM GOING MUCH ABOVE 40-50 PERCENT. WILL
STORMS FORM OVER SOUTHERN ARIZONA AND MOVE NORTHWARD OR WILL STORMS
FORM OVER NORTHERN MARICOPA COUNTY AND MISS PHOENIX
ALTOGETHER...THESE ARE MY MAIN QUESTIONS THIS MORNING. HOPE TO GAIN
SOME CLARITY FROM THE HI-RES WRF MODELS LATER TODAY. SIMILAR
CONVECTIVE DEVELOPMENT IS EXPECTED ON SUNDAY WITH THE BEST CHANCES
FROM PHOENIX WESTWARD TO THE COASTAL MOUNTAINS OF CALIFORNIA.
WESTERLY FLOW ALOFT BEGINS TO TAKE SHAPE ON MONDAY AS THE UPPER
LEVEL PVD MOVES THROUGH SOUTHERN ARIZONA INTO NEW MEXICO. MOISTURE
SHOULD WORK ITS WAY BACK INTO EASTERN ARIZONA AND ALL LOCATIONS
SHOULD SEE A DECENT CHANCE OF SHOWERS AND THUNDERSTORMS. MONDAY
COULD BE THE BEST CHANCE AREA-WIDE FOR PRECIP GIVEN FAVORABLE UPPER
LEVEL SUPPORT AND POPS WERE INCREASED INTO THE 40-50 PERCENT RANGE
TO REFLECT THIS. FOLLOWING THE TROUGH...A GRADUAL DECREASE IN
MOISTURE AND INSTABILITY WILL GREATLY REDUCE THE AMOUNT OF STORMS
FROM TUESDAY ONWARD. COULD SEE A FEW RENEGADE STORMS EAST OF PHOENIX
ON TUESDAY WHERE SOME MOISTURE AND INSTABILITY WILL RESIDE /PER THE
SLOWER ECMWF SOLUTION/ BUT WESTERLY FLOW WILL STEER THESE STORMS
AWAY FROM THE DESERTS. 1000-700MB MOISTURE DROPS ALL THE WAY DOWN TO
AROUND 6 G/KG ON WEDNESDAY WITH BARELY ANY INSTABILITY TO SPEAK OF
ANYWHERE IN THE STATE. MAY STRUGGLE TO EVEN GET AFTERNOON CU LATE
NEXT WEEK AND POPS WERE REDUCED WELL BELOW CLIMO FOR THE END OF THE
FORECAST PERIOD.
WITH ELEVATED MOISTURE...TEMPS SHOULD STAY AOB NORMAL THROUGH AT
LEAST THE MIDDLE OF NEXT WEEK. TEMPS WILL CLIMB SLIGHTLY FROM THE
MIDDLE OF NEXT WEEK ONWARD IN RESPONSE TO DECREASING MOISTURE BUT
STILL IN THE BALLPARK OF NORMAL FOR MID SEPTEMBER.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...
A WEAK WEATHER DISTURBANCE ALONG WITH ABUNDANT MOISTURE OVER THE
SOUTHERN HALF OF ARIZONA WILL LEAD TO SHOWER AND THUNDERSTORM
ACTIVITY IN SOMETHING OF A RANDOM PATTERN THIS MORNING. SHWRS/TSTMS
WILL BE POSSIBLE ANYWHERE DESPITE THE LACK OF SURFACE HEATING. THUS
THE VCSH/VCTS IN THE PHOENIX AREA TAFS. NAM MODEL SEEMS TO BE DOING
A BETTER JOB EARLY THIS MORNING THAN THE GFS AND IT INDICATES MORE
SHOWER ACTIVITY THIS MORNING THAN LATER THIS AFTERNOON. 09Z RUC
INDICATES THIS AS WELL. WITH ALL THE MOISTURE AND
CLOUDINESS...OPTIMAL INSTABILITY MAY NOT BE REALIZED. THIS...ALONG
WITH UNCERTAINTIES IN TIMING AND LOCATION OF PRECIP IS WHY TEMPO
SHRA/TSRA WAS WITHHELD FROM THE TAFS. ANY TSTMS THAT MOVE OVER AN
AIRFIELD WILL BE ABLE TO REDUCE VSBYS AT OR BELOW 6SM IN HEAVY RAIN.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
NAM AND RUC INDICATE THAT THE LOWER COLORADO RIVER VALLEY WILL HAVE
A BETTER CHANCE AT PRECIP THIS AFTERNOON THAN THE IMPERIAL VALLEY. A
LOT OF UNCERTAINTIES REMAIN REGARDING INSTABILITY AND THUS THE
OCCURRENCE OF CONVECTIVE SHOWERS. ANTICIPATE THAT LA PAZ COUNTY WILL
BE ACTIVE ENOUGH LATER TODAY TO PRODUCE STORMS IN THE VICINITY OF
KBLH. CANT RULE OUT STORM POSSIBILITIES FOR KIPL BUT TOO LOW AT THIS
TIME TO REFLECT IN THE TAFS. SIGNIFICANTLY REDUCED VISIBILITIES IN
HEAVY RAIN WILL BE POSSIBLE WITH THE STRONGER SHOWERS.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
SUNDAY THROUGH THURSDAY...
LINGERING MOISTURE WILL MAINTAIN AN ELEVATED CHANCE OF THUNDERSTORMS
FOR EARLY NEXT WEEK. DEEPER WESTERLY FLOW WILL LEAD TO A DOWNTREND
IN ATMOSPHERIC MOISTURE BEGINNING TUESDAY. THUS...HUMIDITIES AND
STORM CHANCES WILL DECLINE FROM WEST TO EAST. THERE WILL BE ONLY A
SLIGHT CHANCE OF THUNDERSTORMS LEFT OVER THE HIGHER TERRAIN OF
SOUTH-CENTRAL ARIZONA ON WEDNESDAY AND THURSDAY. MINIMUM HUMIDITIES
WILL DROP INTO THE UPPER TEENS OVER SOUTHEAST CALIFORNIA BY
THURSDAY. APART FROM THUNDERSTORM OUTFLOWS...NO STRONG WINDS ARE
ANTICIPATED. AFTERNOON WINDS ARE EXPECTED TO FAVOR SOUTHWEST AND
WESTERLY DIRECTIONS FOR MOST AREAS BEGINNING TUESDAY.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
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DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...LEINS
AVIATION...AJ
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS TUCSON AZ
950 AM MST FRI SEP 7 2012
.SYNOPSIS...ABUNDANT MOISTURE WILL RESULT IN MAINLY AFTERNOON AND
EVENING THUNDERSTORMS INTO EARLY NEXT WEEK. EXPECT HEAVY RAINFALL
WITH THE STRONGER THUNDERSTORMS.
&&
.DISCUSSION...SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ONGOING
ACROSS SOUTH CENTRAL PINAL COUNTY AND WRN/CENTRAL PIMA COUNTY WEST
OF TUCSON AT THIS TIME. ELSEWHERE...PRECIP-FREE CONDITIONS THUS FAR.
HOWEVER...07/12Z UNIV OF AZ WRF-NAM AND 07/12Z-13Z RUC HRRR WERE
VERY SIMILAR WITH PROGGED PRECIP INTO THIS EVENING.
IN ESSENCE...PRECIP TO DECREASE IN COVERAGE AND INTENSITY WEST OF
TUCSON DURING THE NEXT FEW HOURS FOLLOWED BY MOSTLY DRY CONDITIONS
THIS AFTERNOON AND THIS EVENING. EAST OF TUCSON...PRECIP TO DEVELOP
IN THE NEXT COUPLE OF HOURS...THEN SCT-NMRS SHOWERS/TSTMS ACROSS
GREENLEE/GRAHAM/COCHISE COUNTIES THIS AFTERNOON INTO THIS EVENING.
SEEMS REASONABLE...PARTICULARLY THE PRECIP FOR ERN SECTIONS...GIVEN
THE ABUNDANT AVAILABLE MOISTURE AND APPROACHING CYCLONIC CIRCULATION
SYSTEM AS PER WATER VAPOR IMAGERY MOVING WWD INTO NERN SONORA.
THUS...HAVE EXPANDED THE FLASH FLOOD WATCH TO INCLUDE ALL OF SE AZ
UNTIL 8 PM MST THIS EVENING. IF THE AFOREMENTIONED SOLUTIONS COME
CLOSE TO REALITY...WILL LIKELY CANCEL THE FLASH FLOOD WATCH EARLY
THIS AFTERNOON FOR LOCALES WEST OF TUCSON AND MAINTAIN THE FLASH
FLOOD WATCH FROM TUCSON EWD.
PLEASE REFER TO THE PREVIOUS DISCUSSION SECTION BELOW FOR ADDITIONAL
FORECAST DETAIL. ALSO...PLEASE REFER TO THE CLIMATE SECTION BELOW
FOR DETAIL REGARDING THE 07/12Z KTWC SOUNDING.
&&
.PREV DISCUSSION...DEBRIS CLOUD WITH EMBEDDED SHOWERS THIS
MORNING...EXPECT THAT TO CONTINUE TO SLOWLY THIN THROUGH THE MORNING
HOURS WITH PARTIAL CLEARING BY LATE MORNING. ABUNDANT MOISTURE WITH
PRECIPITABLE WATER VALUES IN THE 1.75 TO 2 INCH RANGE...SOMETHING ON
THE ORDER OF 200 PERCENT OF CLIMO. INITIAL IMPULSE THAT HELPED
ORGANIZE CONVECTION LIFTING NORTHWEST OF THE AREA THIS MORNING BUT
WATER VAPOR IMAGERY INDICATING ANOTHER EASTERLY IMPULSE SHIFTING
ACROSS NORTHWEST CHIHUAHUA INTO NORTHEAST SONORA. NAM12 AND ECMWF
GRAB THIS FEATURE AND KICK OFF ANOTHER BUSY DAY WITH A FOCUS THROUGH
PIMA...SANTA CRUZ AND SOUTHERN COCHISE COUNTIES. MAY NEED A FLASH
FLOOD WATCH TODAY AND THOSE AREAS WOULD BE A FIRST GUESS FOR A
STARTING POINT.
LARGER SCALE WEAKNESS IN THE FLOW SHIFTS TOWARD SOUTHWEST ARIZONA
WITH AN EMPHASIS TO WESTERN AREAS OVER THE WEEKEND. HIGHER LATITUDE
FLOW SHOULD MANAGE TO GRAB THIS FEATURE AND DRAG IT BACK EASTWARD
MONDAY OR TUESDAY FOR ANOTHER BIG KICK TO THE THUNDERSTORM FORECAST.
ULTIMATELY THE UPSTREAM FOR THAT WESTERLY FLOW WILL DRY OUT SOONER
OR LATER...WITH A DOWNTURN IN THUNDERSTORMS COVERAGE EXPECTED BY THE
SECOND HALF OF NEXT WEEK.
&&
.AVIATION...SCT TO NUMEROUS TSRA/SHRA WEST AND NW OF KTUS BECOMING
ISOLD-SCT TSRA/SHRA THIS AFTERNOON INTO THIS EVENING. EAST OF KTUS...
PRECIP DEVELOPING LATE THIS MORNING AND BECOMING SCT TO NUMEROUS
TSRA/SHRA THIS AFTERNOON INTO THIS EVENING. PRECIP DECREASING AREA
WIDE LATE TONIGHT ALTHOUGH SCT -TSRA/-SHRA CONTINUING. OTHERWISE...
VFR CONDITIONS AND GENERALLY LIGHT WINDS THRU SATURDAY MORNING OR
08/12Z. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...AN UPPER LEVEL DISTURBANCE ACROSS THE AREA WILL
BRING WETTING RAINFALL TO MOST OF SOUTHEAST ARIZONA INTO EARLY NEXT
WEEK. WINDS WILL INCREASE ACROSS MOST OF ZONE 148 AND SOUTHERN HALF
OF ZONE 146 SATURDAY AS THE SYSTEM BEGINS TO EXIT THE REGION TO THE
WEST. OTHERWISE...LIGHT DIURNAL WIND TRENDS ARE EXPECTED INTO EARLY
NEXT WEEK.
&&
.CLIMATE...07/12Z KTWC TOTAL PRECIP WATER VALUE OF 1.99 INCHES IS
THE HIGHEST RECORDED VALUE BASED ON UPPER AIR DATA RECORDS SINCE
1951. THE YEARLY TIME SERIES PLOT MAY BE FOUND AT (ALL LOWERCASE
EXCEPT FOR TWC):
HTTP://WWW.CRH.NOAA.GOV/UNR/INCLUDE/PW.PHP?SID=TWC
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 8 PM MST THIS EVENING FOR AZZ501>515.
&&
$$
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AREA FORECAST DISCUSSION...UPDATED
NWS PHOENIX AZ
540 AM MST FRI SEP 7 2012
.UPDATE...
UPDATED AVIATION AND FIRE WEATHER SECTIONS.
&&
.SYNOPSIS...
A VERY MOIST AND UNSTABLE MONSOON AIRMASS WILL CONTINUE TO COVER THE
REGION THROUGH EARLY NEXT WEEK...AND LEAD TO A CHANCE OF MAINLY
AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS EACH DAY.
THUNDERSTORM COVERAGE AND INTENSITY WILL VARY FROM DAY TO DAY...WITH
SOMEWHAT BETTER CHANCES EXPECTED OVER THE WEEKEND AND INTO NEXT
MONDAY. HIGH TEMPERATURES WILL REMAIN NEAR OR SLIGHTLY BELOW
SEASONAL NORMALS EACH DAY GIVEN THE HIGH MOISTURE CONTENT IN THE
ATMOSPHERE.
&&
.DISCUSSION...
COMPLICATED WEATHER PATTERN ESTABLISHING ITSELF ACROSS THE REGION
THIS MORNING FOLLOWING A SOMEWHAT ACTIVE DAY ON THURSDAY. PORTIONS
OF SOUTHERN ARIZONA DID VERY WELL PRECIP-WISE YESTERDAY WHILE THE
MAJORITY OF THE PHOENIX METRO ONLY SAW DUST...A FEW HUNDREDTHS HERE
AND THERE...A FEW TENTHS IN THE FAR NW VALLEY. WATER VAPOR AND RADAR
IMAGERY AT 09Z REVEAL REMNANT CONVECTION ACROSS EASTERN ARIZONA AND
A DEVELOPING MCV ACROSS SOUTHERN GILA COUNTY. WHILE STORMS DO NOT
APPEAR STRONG AT THIS TIME...ACARS SOUNDINGS CONTINUE TO REVEAL
300-400 J/KG OF UNCAPPED CAPE ABOVE 750MB...MOST LIKELY THE REASON
THESE STORMS REFUSE TO DIE OFF 9 HRS AFTER SUNSET. ALSO SOME HINT OF
SOME DEVELOPING CONVECTION ACROSS CENTRAL PIMA COUNTY ALTHOUGH THAT
PORTION OF THE STATE WAS WORKED OVER PRETTY HEAVILY ON THURSDAY.
A FEW SPOT CHECKS ACROSS THE REGION REVEAL THE 00Z NAM HAS
INITIALIZED THE TEMP/MOISTURE/WIND FIELDS BETTER THAN THE GFS AND
EURO.../GFS LOOKS ENTIRELY TOO DRY AT NEARLY ALL SITES/ THUS THE
FORECAST FOR THE FIRST 24 HOURS WILL BE HEAVILY WEIGHTED TOWARD THE
NAM SOLUTION. THE NAM SHOWS LINGERING CONVECTION ACROSS PORTIONS OF
SE AZ THIS MORNING...GRADUALLY TRANSITIONING TO A MORE TYPICAL
MONSOON ORIENTATION ALONG THE RIM LATER THIS AFTERNOON. ABUNDANT
MOISTURE WITH MIXING RATIOS AROUND 12 G/KG AND MLCAPES AOA 1000 J/KG
ARE ONLY PART OF THE EQUATION NATURALLY...BIG QUESTION IS WHETHER
THE REMNANT MCV WILL ALLOW FOR ANY STORMS TO MOVE OFF THE RIM AND
INTO THE VALLEY LATER TODAY. AT THIS POINT IT LOOKS TO BE A
SLIGHTLY-MORE-ACTIVE-THAN-USUAL DAY AND POPS WERE DRAWN APPROX 10
PERCENT ABOVE CLIMO GIVEN THE PRESENCE OF THE MCV IN THE AREA. ONE
CONCERN WORTH MENTIONING IS LINGERING CLOUD COVER AS IT WILL TAKE A
FEW HOURS TO SCOUR OUT ALL THE MID AND HIGH MOISTURE AND MAY NOT BE
MOSTLY SUNNY UNTIL LATE MORNING.
THE WEEKEND LOOKS TO BE PARTICULARLY ACTIVE AND THE MODELS HAVE BEEN
HINTING AT THIS FOR THE PAST FEW DAYS. A FEW 700-300MB INVERTED
TROUGHS ARE EXPECTED TO MOVE THROUGH THE REGION THIS WEEKEND...AND
SHOULD INTERACT WITH A LARGER MORE WELL DEFINED 200-300MB PVD
/PRESENTLY OVER BAJA CALIFORNIA/. INTERESTINGLY ENOUGH...THE USUALLY
ACTIVE PORTIONS NORTH AND EAST OF PHOENIX MAY SEE A BIT OF A BREAK
AT TIMES THIS WEEKEND AS THE GREATEST MOISTURE AND INSTABILITY
ORIENT INTO A LAS VEGAS TO NOGALES AXIS. ALL GUIDANCE PRETTY MUCH
AGREES THAT SOUTHERN GILA COUNTY MAY SEE LITTLE TO NO INSTABILITY
SATURDAY AND SUNDAY. NOT SAYING THESE AREAS WILL BE DRY
ALTOGETHER...BUT I REFINED THE POPS TO BETTER REFLECT THE AXIS OF
MOISTURE/INSTABILITY. POPS WERE INCREASED ACROSS THE PHOENIX METRO
AS WELL BUT AS USUAL...THERE IS JUST ENOUGH UNCERTAINTY IN THE
GUIDANCE TO PRECLUDE ME FROM GOING MUCH ABOVE 40-50 PERCENT. WILL
STORMS FORM OVER SOUTHERN ARIZONA AND MOVE NORTHWARD OR WILL STORMS
FORM OVER NORTHERN MARICOPA COUNTY AND MISS PHOENIX
ALTOGETHER...THESE ARE MY MAIN QUESTIONS THIS MORNING. HOPE TO GAIN
SOME CLARITY FROM THE HI-RES WRF MODELS LATER TODAY. SIMILAR
CONVECTIVE DEVELOPMENT IS EXPECTED ON SUNDAY WITH THE BEST CHANCES
FROM PHOENIX WESTWARD TO THE COASTAL MOUNTAINS OF CALIFORNIA.
WESTERLY FLOW ALOFT BEGINS TO TAKE SHAPE ON MONDAY AS THE UPPER
LEVEL PVD MOVES THROUGH SOUTHERN ARIZONA INTO NEW MEXICO. MOISTURE
SHOULD WORK ITS WAY BACK INTO EASTERN ARIZONA AND ALL LOCATIONS
SHOULD SEE A DECENT CHANCE OF SHOWERS AND THUNDERSTORMS. MONDAY
COULD BE THE BEST CHANCE AREA-WIDE FOR PRECIP GIVEN FAVORABLE UPPER
LEVEL SUPPORT AND POPS WERE INCREASED INTO THE 40-50 PERCENT RANGE
TO REFLECT THIS. FOLLOWING THE TROUGH...A GRADUAL DECREASE IN
MOISTURE AND INSTABILITY WILL GREATLY REDUCE THE AMOUNT OF STORMS
FROM TUESDAY ONWARD. COULD SEE A FEW RENEGADE STORMS EAST OF PHOENIX
ON TUESDAY WHERE SOME MOISTURE AND INSTABILITY WILL RESIDE /PER THE
SLOWER ECMWF SOLUTION/ BUT WESTERLY FLOW WILL STEER THESE STORMS
AWAY FROM THE DESERTS. 1000-700MB MOISTURE DROPS ALL THE WAY DOWN TO
AROUND 6 G/KG ON WEDNESDAY WITH BARELY ANY INSTABILITY TO SPEAK OF
ANYWHERE IN THE STATE. MAY STRUGGLE TO EVEN GET AFTERNOON CU LATE
NEXT WEEK AND POPS WERE REDUCED WELL BELOW CLIMO FOR THE END OF THE
FORECAST PERIOD.
WITH ELEVATED MOISTURE...TEMPS SHOULD STAY AOB NORMAL THROUGH AT
LEAST THE MIDDLE OF NEXT WEEK. TEMPS WILL CLIMB SLIGHTLY FROM THE
MIDDLE OF NEXT WEEK ONWARD IN RESPONSE TO DECREASING MOISTURE BUT
STILL IN THE BALLPARK OF NORMAL FOR MID SEPTEMBER.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...
A WEAK WEATHER DISTURBANCE ALONG WITH ABUNDANT MOISTURE OVER THE
SOUTHERN HALF OF ARIZONA WILL LEAD TO SHOWER AND THUNDERSTORM
ACTIVITY IN SOMETHING OF A RANDOM PATTERN THIS MORNING. SHWRS/TSTMS
WILL BE POSSIBLE ANYWHERE DESPITE THE LACK OF SURFACE HEATING. THUS
THE VCSH/VCTS IN THE PHOENIX AREA TAFS. NAM MODEL SEEMS TO BE DOING
A BETTER JOB EARLY THIS MORNING THAN THE GFS AND IT INDICATES MORE
SHOWER ACTIVITY THIS MORNING THAN LATER THIS AFTERNOON. 09Z RUC
INDICATES THIS AS WELL. WITH ALL THE MOISTURE AND
CLOUDINESS...OPTIMAL INSTABILITY MAY NOT BE REALIZED. THIS...ALONG
WITH UNCERTAINTIES IN TIMING AND LOCATION OF PRECIP IS WHY TEMPO
SHRA/TSRA WAS WITHHELD FROM THE TAFS. ANY TSTMS THAT MOVE OVER AN
AIRFIELD WILL BE ABLE TO REDUCE VSBYS AT OR BELOW 6SM IN HEAVY RAIN.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
NAM AND RUC INDICATE THAT THE LOWER COLORADO RIVER VALLEY WILL HAVE
A BETTER CHANCE AT PRECIP THIS AFTERNOON THAN THE IMPERIAL VALLEY. A
LOT OF UNCERTAINTIES REMAIN REGARDING INSTABILITY AND THUS THE
OCCURRENCE OF CONVECTIVE SHOWERS. ANTICIPATE THAT LA PAZ COUNTY WILL
BE ACTIVE ENOUGH LATER TODAY TO PRODUCE STORMS IN THE VICINITY OF
KBLH. CANT RULE OUT STORM POSSIBILITIES FOR KIPL BUT TOO LOW AT THIS
TIME TO REFLECT IN THE TAFS. SIGNIFICANTLY REDUCED VISIBILITIES IN
HEAVY RAIN WILL BE POSSIBLE WITH THE STRONGER SHOWERS.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
SUNDAY THROUGH THURSDAY...
LINGERING MOISTURE WILL MAINTAIN AN ELEVATED CHANCE OF THUNDERSTORMS
FOR EARLY NEXT WEEK. DEEPER WESTERLY FLOW WILL LEAD TO A DOWNTREND
IN ATMOSPHERIC MOISTURE BEGINNING TUESDAY. THUS...HUMIDITIES AND
STORM CHANCES WILL DECLINE FROM WEST TO EAST. THERE WILL BE ONLY A
SLIGHT CHANCE OF THUNDERSTORMS LEFT OVER THE HIGHER TERRAIN OF
SOUTH-CENTRAL ARIZONA ON WEDNESDAY AND THURSDAY. MINIMUM HUMIDITIES
WILL DROP INTO THE UPPER TEENS OVER SOUTHEAST CALIFORNIA BY
THURSDAY. APART FROM THUNDERSTORM OUTFLOWS...NO STRONG WINDS ARE
ANTICIPATED. AFTERNOON WINDS ARE EXPECTED TO FAVOR SOUTHWEST AND
WESTERLY DIRECTIONS FOR MOST AREAS BEGINNING TUESDAY.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...LEINS
AVIATION...AJ
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS TAUNTON MA
153 PM EDT FRI SEP 7 2012
.SYNOPSIS...
A DIFFUSE FRONTAL BOUNDARY ACROSS THE REGION WILL LIFT BACK
NORTHWARD DURING THE COURSE OF TODAY INTO TONIGHT AS A WARM
FRONT. A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS IS
POSSIBLE ALONG THE FRONT...OTHERWISE REMAINING DRY AND HUMID INTO
SATURDAY. SHOWERS AND THUNDERSTORMS ARE LIKELY SATURDAY NIGHT AS A
STRONG COLD FRONT MOVES ACROSS THE REGION. MUCH COOLER AND DRIER
WEATHER WILL FOLLOW EARLY NEXT WEEK...THEN A SLOW WARMING TREND
TOWARD THE LATTER HALF OF THE WEEK. HURRICANE LESLIE WILL TRACK
SEVERAL HUNDRED MILES EAST OF NEW ENGLAND BUT BRING DANGEROUS SURF
TO THE SOUTHERN NEW ENGLAND COAST THIS WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
200 PM UPDATE...
FORECAST CONTINUES TO STAY ON TRACK. HAVE PUSHED BACK POPS TIL
AFTER 18Z PER LATEST HRRR MODEL RUN. OTHERWISE CU FIELD IS SLOWLY
DEVELOPING ALONG THE SOUTH SHORE SEA BREEZE. WITH MODEST
INSTABILITY MAY SEE AN ISOLATED CONVECTION...AM NOT EXPECTING
ANYTHING WIDESPREAD. LIMITING FACTOR WOULD BE CELL UPDRAFT...WITH
A VERY DRY AIR ALOFT...EXPECT CELLS TO REMAIN LOW TOPPED. GOOD
AMOUNT OF LOW LEVEL MOISTURE PER LATEST DEWPOINT OBSERVATION SO THE
POTENTIAL IS THERE. WILL HAVE TO MONITOR RADAR AND LATEST
CONDITIONS. OTHERWISE MADE SOME MINOR UPDATES TO THE FORECAST TO
ACCOUNT FOR CURRENT TRENDS. TEMPS CONTINUE TO BE ON THE RISE...AND
WIT THE SEA BREEZES PUSHING INWARD...ALONG THE COAST MAY BE A TAD
COOLER. OVERALL A DECENT DAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
TONIGHT...
LOOKING AT A QUIET NIGHT WITH STRONG SLY FLOW KEEPING SFC TEMPS
NEAR-STABLE AND MILD IN AND AROUND THE MID-UPR 60S. THE ABUNDANCE OF
LOW-LVL MOISTURE BELOW THE NOCTURNAL INVERSION WILL LIKELY RESULT IN
A MIX OF PATCHY FOG AND LOW-LYING STRATUS. AS ALLUDED TO BY THE PREV
FCSTR...IT/S PLAUSIBLE TO SEE TROPICAL MOISTURE STREAMING NWD FROM
LESLIE TOWARDS THE S SHORELINE OF NEW ENGLAND. LATEST MDL GUIDANCE
SUGGESTS IT SHOULD REMAIN WELL OFFSHORE PRIOR TO SATURDAY MORNING.
SATURDAY...
THERE ARE SOME SUBTLE DIFFERENCES IN THE 07/0Z FCST GUIDANCE WORTH
NOTING...SUCH AS THE STRENGTH AND POSITION OF THE SFC LOW PRES
CENTER AND ATTENDANT STRENGTH OF THE LLJ ALONG AND AHEAD OF THE
TRAILING SFC COLD FRNT. NEVERTHELESS...THERE IS BETTER AGREEMENT
AMONGST THE GUIDANCE ON THE TIMING OF THE SYS FOR THE LATE PD INTO
SATURDAY NIGHT. THRU THE DAY...STRONG ONSHORE SLY FLOW /SUSTAINED
AROUND 10-15 MPH WITH GUSTS UP TO 25 MPH/ SHOULD ADVECT TROPICAL AIR
NWD WITH LOW 70 DWPTS. LOOKING TO BE A MILD AND SULTRY DAY. WAA
PREVAILING BETWEEN H925-85 MAY ACT TO CAP THE LOWER ATMOS...
RESULTING IN MOISTURE POOLING WITHIN THE BOUNDARY LYR AND
DEVELOPMENT OF LOW-LVL STRATUS. ANTICIPATING PARTLY SUNNY CONDITIONS
WITH THE POSSIBILITY THAT LOW-LVLS WILL MIX OUT ALLOWING FOR
ENTRAINMENT OF DRIER AIR ALOFT /ABOVE H85/. LOWERING HEIGHTS ACROSS
THE RGN COMBINED WITH OROGRAPHIC LIFT AND LOW-LVL MOISTURE
CONVERGENCE OF THE ONSHORE TROPICAL AIRMASS MAY RESULT IN SCTD LIGHT
SHOWER ACTIVITY PRIOR TO THE MAIN SHOW. WILL LEAN MORESO TOWARDS THE
06/21Z SREF POPS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
HIGHLIGHTS...
* SHOWERS AND THUNDERSTORMS SAT NIGHT...IMPROVING CONDITIONS SUNDAY
* DRY AND MUCH COOLER EARLY NEXT WEEK FOLLOWED BY A WARMING TREND
OVERVIEW...
MODELS HAVE COME INTO BETTER AGREEMENT ON TIMING OF COLD FRONT AND
ASSOCD SHOWERS/TSTMS SAT NIGHT WITH GRADUAL IMPROVING CONDITIONS
SUNDAY. AN EXTENDED PERIOD OF DRY WEATHER IS EXPECTED FOR MUCH OF
NEXT WEEK WITH BELOW NORMAL TEMPS TO START THE WEEK FOLLOWED BY A
GRADUAL MODERATING TREND. ECMWF IS SLOWER THAN GFS LIFTING THE MID
LEVEL TROF AWAY FROM NEW ENG...BUT THE MAIN EFFECT OF THIS
DIFFERENCE WILL BE HOW QUICKLY WARMER AIR RETURNS TO SNE.
SAT NIGHT INTO SUNDAY...
COLD FRONT WILL BE MOVING ACROSS SNE SAT NIGHT REACHING THE CAPE AND
ISLANDS AROUND 12Z SUN. FAVORABLE JET DYNAMICS WITH LOW LEVEL JET
COLLOCATED WITH RIGHT ENTRANCE REGION OF UPPER JET WHICH WILL RESULT
IN AN AREA OF ENHANCED OMEGA MOVING ACROSS THE REGION SAT NIGHT.
THIS COMBINED WITH HIGH PWAT AIRMASS AND ELEVATED INSTABILITY WILL
BRING A PERIOD OF SHOWERS AND SCT THUNDERSTORMS. FRONT IS
PROGRESSIVE SO WE DONT EXPECT EXCESSIVE RAINFALL BUT BRIEF HEAVY
DOWNPOURS ARE POSSIBLE. NAM IS MORE ROBUST WITH THE LOW LEVEL JET
AND OMEGA RESULTING IN GREATER QPF...BUT IS AN OUTLIER COMPARED TO
GFS/ECMWF. GIVEN THAT MAIN THRUST OF SHORTWAVE ENERGY IS LIFTING TO
THE N SAT NIGHT WE LEANED TOWARD THE GFS/ECMWF.
FRONT WILL BE MOVING TO THE E ON SUNDAY. SHOWERS ARE LIKELY EARLY
SUNDAY...MAINLY ACROSS E NEW ENG AND COULD LINGER INTO THE AFTERNOON
CAPE/ISLANDS IF SLOWER ECMWF IS CORRECT. WE LEANED TOWARD SLIGHTLY
FASTER GFS WHICH SUGGESTS PARTIAL CLEARING MOVING IN FROM WEST TO
EAST.
MONDAY THROUGH THURSDAY...
THIS PERIOD WILL BE DOMINATED BY HIGH PRESSURE RESULTING IN AN
EXTENDED PERIOD OF DRY WEATHER. IT WILL BE A COOL START TO THE WEEK
WITH BELOW NORMAL TEMPS EXPECTED...THEN A MODERATING TREND TOWARD
THE LATTER HALF OF THE WEEK AS MID LEVEL RIDGE BUILDS IN FROM THE
WEST WITH RISING HEIGHTS. GFS IS PROBABLY TOO QUICK LIFTING THE MID
LEVEL TROF OUT SO WARMER AIRMASS WILL LIKELY BE DELAYED TIL WED OR
THU.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
OVERVIEW...MODERATE CONFIDENCE.
DIURNAL CU WILL CONTINUE TO DEVELOP UNDER LGT AND VRB
FLOW. WINDS WILL TURN MORE SLY LATE INTO THE DAY AND OVRNGT. SEA
BREEZE SHLD DISSIPATE BY SUNSET. VSBYS AND LOW-STRATUS SHOULD
REAPPEAR DURING THE OVRNGT PD AND CONTINUE INTO SATURDAY.
UNCERTAIN ON TIMING OF DISSIPATION. WINDS WILL BE GUSTING AT AROUND
20 KTS ALONG AND AHEAD OF AN APPROACHING COLD FRNT FOR SAT NIGHT.
SHRA/TSRA WILL INCREASE LATE SAT INTO THE OVERNIGHT PERIOD.
KBOS TAF...MODERATE CONFIDENCE.
VFR TODAY WITH SEA-BREEZES INTO THE MIDDAY PD RESULTING IN MOSTLY
CLEAR TO SCT CONDITIONS. SLY FLOW OVRNGT WITH PSBL LOW-LVL STRATUS
REAPPEARING INTO SATURDAY MORNING. TSRA/SHRA LOOKS LIKELY SAT
NIGHT.
KBDL TAF...MODERATE CONFIDENCE.
VRB WINDS BECOMING SLY THIS AFTERNOON. LOW CONFIDENCE ON SHRA/TSRA
TODAY...BUT CAN/T RULE OUT THE POSSIBILITY. SOUTHERLY FLOW
OVERNIGHT WITH LOW-STRATUS TONIGHT INTO SATURDAY. TSRA/SHRA
CONDITIONS LATE SATURDAY...LOWERING TO MVFR/IFR.
OUTLOOK...SATURDAY NIGHT THROUGH TUESDAY...
SATURDAY NIGHT INTO SUNDAY...
MODERATE TO HIGH CONFIDENCE IN A PERIOD OF MVFR/IFR SAT NIGHT AS
SHOWERS MOVE ACROSS THE REGION WITH AREAS OF STRATUS AND PATCHY
FOG. SHOWERS AND LOWER CONDITIONS MAY PERSIST INTO EARLY
SUNDAY...MAINLY E NEW ENG BUT IMPROVING CONDITIONS TO VFR EXPECTED
FROM WEST TO EAST.
MONDAY INTO TUESDAY...VFR. HIGH CONFIDENCE.
&&
.MARINE...
OVERVIEW...MODERATE TO HIGH CONFIDENCE.
FCST GUIDANCE SUGGESTS A SLIGHT DECREASE IN SWELLS THROUGH THE
FORECAST PERIOD INTO THE EARLY PART OF NEXT WEEKEND WITH A
CONSISTENT WAVE PERIOD AROUND 12 SECONDS. WAVE HEIGHTS REMAIN
FAIRLY STABLE...ONLY TO RESURGE WITH INCREASING SLY FLOW AHEAD OF
AN AREA OF LOW PRES APPROACHING THE WATERS INTO THE WEEKEND...AND
THE CLOSE PROXIMITY PASSAGE OF LESLIE. WHILE THERE MAY BE THE SLGT
CHC OF SHOWERS AND THUNDERSTORMS DURING THE PD /ESPECIALLY LATER
CLOSER TO SATURDAY NIGHT/ A MORE SIGNIFICANT IMPACT MAY BE PATCHY
FOG DURING THE OVRNGT HRS.
OUTLOOK...SATURDAY NIGHT THROUGH TUESDAY...
MODERATE TO HIGH CONFIDENCE...
A PERIOD OF SCA PREFRONTAL S/SW GUSTS EXPECTED SAT NIGHT AS LOW
LEVEL JET MOVES ACROSS THE REGION. A TEMPORARY DECREASE IN WINDS
SUNDAY...THEN NW WIND GUSTS MAY APPROACH 25 KT AT TIMES LATE SUN
NIGHT INTO TUESDAY. INCREASING SE SWELL FROM LESLIE EXPECTED THIS
WEEKEND INTO EARLY NEXT WEEK RESULTING IN HAZARDOUS SEA CONDITIONS
THROUGH MUCH OF THE PERIOD.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 3 PM EDT
SATURDAY FOR ANZ235-237-254>256.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 8 PM THIS EVENING
TO 3 PM EDT SATURDAY FOR ANZ250.
&&
$$
SYNOPSIS...KJC/SIPPRELL
NEAR TERM...DUNTEN
SHORT TERM...SIPPRELL
LONG TERM...KJC
AVIATION...KJC/DUNTEN
MARINE...KJC/SIPPRELL
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1154 PM CDT THU SEP 6 2012
.DISCUSSION...
ISSUED 900 PM CDT THU SEP 6 2012
DRY AIR MIXING THIS AFTERNOON DROPPED SURFACE DEWPOINTS INTO THE
LOW TO MID 50S IN SOME WESTERN AREAS...WITH EAST AND SOUTHEAST
AREA DEWPOINTS STILL IN THE 60S. ANY FOG FORMATION UNDER THE CLEAR
SKIES AND LIGHT WINDS WILL BE IN THE ESE COUNTIES. WESTERN AREAS
SHOULD SEE LIMITED FOG IF AT ALL.
THE NEXT ISSUE WILL BE WHEN THE STORM COMPLEX WILL ARRIVE FROM
IOWA. THE LATEST HRRR MODEL OUTPUT KEEPS ALL STORMS IN IOWA
THROUGH 6 AM...SO CONFIDENCE IS DROPPING THAT ANY STORMS WILL
REACH OUR NW COUNTIES BEFORE SUNRISE. WE REMAIN IN THE DAY 1 SPC
SEVERE OUTLOOK FOR KNOX AND FAR NW FULTON COUNTIES VALID THROUGH
12Z. WILL KEEP LIKELY POPS IN THAT AREA FOR LATE TONIGHT...BUT
PULLED OUT POPS THROUGH 9Z...THEN KEPT LIMITED POPS FROM 9Z-12Z
LATER TONIGHT.
THE MAIN SHOW FOR STORMS WILL BE ON FRIDAY...ESPECIALLY FRIDAY
AFTERNOON EAST OF I-55 WHEN PEAK HEATING AND INSTABILITY/SHEAR
BECOME MORE FAVORABLE FOR SEVERE STORMS.
UPDATED GRIDS AND FORECAST INFO WILL BE AVAILABLE SHORTLY.
SHIMON
&&
.AVIATION...
ISSUED 1154 PM CDT THU SEP 6 2012...FOR THE 06Z TAFS
STORMS HAVE BEGUN TO FIRE IN CENTRAL IOWA UNDER A SHORTWAVE AHEAD
OF THE COLD FRONT. UNLESS THAT LINE HAS DEVELOPMENT TO THE
SOUTHWEST...THE CURRENT BAND OF CONVECTION WOULD MISS OUR NORTHERN
COUNTIES TO THE NORTH. ASSUMING THE LINE DOES EXPAND TO THE
SW...THE TIMING OF ARRIVAL IN KNOX COUNTY WOULD BE AROUND
1030Z/0520 CDT. BASED ON THAT...THE PIA TERMINAL COULD SEE
CONVECTION AROUND 12Z...SO I BUMPED THE VCTS TO 12Z AND THE STEADY
-SHRA TO 15Z. LIKEWISE...I TRENDED STORMS/PRECIP LATER WITH THE
DOWNSTREAM TAFS.
THE STRONGEST CONVECTION STILL APPEARS TARGETED FOR THE AFTERNOON
NEAR THE EASTERN TERMINALS OF DEC/CMI AND POSSIBLY BMI/SPI. AS A
SURFACE WAVE TRAVELS UP THE FRONT DURING THE AFTERNOON...IT WILL
COMBINE WITH FAVORABLE SHEAR AND INSTABILITY TO PRODUCE STRONG TO
SEVERE STORMS. DAMAGING WINDS WILL BE THE PRIMARY HAZARD FOR THE
EASTERN TERMINAL LOCATIONS...WITH LARGE HAIL ALSO POSSIBLE. STILL
A TOUGH CALL ON THE 2-3 HOUR WINDOW OF PEAK SEVERE STORM
CHANCES...SO WILL NOT INCLUDE AN AFTERNOON TEMPO JUST YET.
WINDS WILL INCREASE OUT OF THE SW IN THE MORNING...THEN VEER TO
THE W-NW AS THE FRONT MOVES THROUGH. NW WINDS WILL DEVELOP IN THE
POST-FRONTAL AIRMASS...WITH STRATIFORM RAIN FOR A FEW HOURS BEHIND
THE FRONT. IFR LOW CLOUDS AND MVFR FOG ARE POSSIBLE FOR THE
EVENING...AS COOLER AIR FILTERS INTO THE MOIST AIRMASS. SOME
LOCALLY DENSE FOG MAY DEVELOP ALREADY IN THE EVENING...BUT WILL
HOLD OFF ON VLIFR CONDITIONS THIS FAR OUT.
SHIMON
&&
.PREV DISCUSSION...
ISSUED 250 PM CDT THU SEP 6 2012
HIGH PRESSURE CENTERED OVER EASTERN IOWA EARLY THIS AFTERNOON.
MOST OF THE FOG ACROSS THE SOUTHEAST HALF OF THE CWA BURNED OFF BY
9 AM OR SO...BUT THE CLOUDS HAVE LINGERED THERE INTO THIS
AFTERNOON. THIS IS ALONG A BOUNDARY/SURFACE FRONT THAT DIVIDES
DEW POINTS IN THE 50S TO THE NORTHWEST...AND AROUND 70 TO THE
SOUTHEAST.
THE LARGER SURFACE PICTURE SHOWS LOW PRESSURE IN NORTH CENTRAL
NEBRASKA...WITH A WARM FRONT ARCHING NORTHEAST INTO CENTRAL
MINNESOTA AND A COLD FRONT EXTENDING WESTWARD. THIS PARTICULAR
STORM SYSTEM IS THE FEATURE OF INTEREST FOR OUR AREA OVER THE NEXT
36 HOURS. THE MAIN CONCERNS WILL BE WITH RAINFALL TIMING AND
AMOUNTS...AS WELL AS SEVERE WEATHER POTENTIAL.
SHORT TERM...TONIGHT THROUGH SATURDAY...
DIGGING UPPER TROUGH CURRENTLY MOVING INTO NORTH DAKOTA WILL PUSH
STORM SYSTEM IN THE PLAINS EASTWARD. STILL LOOKING LIKE THE
WESTERN HALF OF THE CWA WILL BE SEEING SOME SHOWERS AND STORMS
SPREADING IN AFTER MIDNIGHT...ESPECIALLY NORTHWEST OF THE ILLINOIS
RIVER. HAVE ADDED SOME SLIGHT CHANCE POPS AS FAR EAST AS I-57 FOR
LATE TONIGHT.
REASONABLE AGREEMENT EXISTS AMONG MODEL SOLUTIONS ON SWEEPING THE
COLD FRONT ACROSS THE FORECAST AREA FRIDAY AFTERNOON AND EARLY
EVENING...ALTHOUGH THE NAM IS A TAD FASTER IN THIS REGARD. ALL
MODEL SOLUTIONS SHOWING PRECIPITABLE WATER VALUES AROUND 2-2.1
INCHES AHEAD OF THE FRONT...WHICH IS AROUND THE 99TH PERCENTILE
FOR EARLY SEPTEMBER...SO SOME AREAS OF HEAVIER RAIN ARE LIKELY. IN
TERMS OF THE SEVERE POTENTIAL...CAPES PROGGED TO RISE TO AT LEAST
2000 J/KG EAST OF THE RAIN SHIELD...WHERE SOME SUN MAY OCCUR
DURING THE MORNING...AND BULK SHEAR VALUES AHEAD OF THE FRONT
PROGGED TO RISE TO AROUND 40-45 KNOTS. MAINLY LOOKING AT A WIND
DAMAGE AND HAIL THREAT IN THIS AREA. LATEST SPC DAY2 OUTLOOK HAS
AREAS FROM THE ILLINOIS RIVER SOUTHEAST IN A SLIGHT RISK...WITH
THE GREATEST PROBABILITIES SOUTH OF A TAYLORVILLE TO DANVILLE
LINE. RAIN CHANCES SHOULD QUICKLY TAPER OFF FROM WEST TO EAST
FOLLOWING THE PASSAGE OF THE FRONT...WITH MOST AREAS WEST OF I-57
DRY BY LATE FRIDAY EVENING.
UPPER TROUGH WILL CONTINUE TO DEEPEN AS IT SWEEPS ACROSS THE GREAT
LAKES SATURDAY. WILL CONTINUE WITH HIGHS IN THE LOWER 70S ACROSS
MOST OF THE CWA AS THE COLDER AND DRIER AIR IS DRAWN SOUTHWARD.
LONG TERM...SUNDAY THROUGH THURSDAY...
HIGH TEMPERATURES REMAIN IN THE 70S SUNDAY AND MONDAY...AS THE
UPPER TROUGH GRADUALLY LIFTS NORTHEAST INTO CANADA...WITH SOME
GRADUAL WARMING AFTER THAT. MAIN CONCERN IN THE LONGER TERM
REMAINS WITH A SHORTWAVE WHICH WILL TRACK ALONG THE CANADIAN
BORDER EARLY IN THE WEEK. ECMWF AND GFS MODELS HAVING SOME
DIFFICULTY WITH THE FAST UPPER FLOW...AND WHEN TO BRING THIS INTO
OUR GENERAL REGION. BOTH MODELS SHOW A SLOWING OF THE ASSOCIATED
SURFACE FRONT BY MIDWEEK AS IT STARTS TO PARALLEL THE UPPER
FLOW... DUE TO A 500 MB HIGH STRETCHED EAST-WEST ACROSS THE
SOUTHEASTERN STATES. MAIN PRECIPITATION FOCUS WOULD LIKELY HOLD
OFF UNTIL THURSDAY IN OUR AREA...BUT A FAIR AMOUNT OF DRY AIR WILL
STILL BE OVER THE CWA. THEREFORE...WILL ONLY GO WITH SOME SLIGHT
CHANCE POPS ACROSS THE NORTHWEST FOR NOW.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
231 PM MDT FRI SEP 7 2012
.SHORT TERM...(THIS AFTERNOON THROUGH TONIGHT)
ISSUED AT 210 PM MDT FRI SEP 7 2012
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW POSITIVELY TILTED TROUGH
OVER NORTHERN GREAT LAKES WITH AXIS EXTENDING SOUTHWEST ACROSS
CENTRAL NEBRASKA. LARGE SCALE SUBSIDE IS CURRENTLY BUILDING INTO
TRI-STATE AREA AS THIS TROUGH SHIFTS EAST. AT THE SURFACE HIGH
PRESSURE BUILDING INTO THE CWA FROM THE NORTHWEST.
ISOLATED LIGHT SHOWERS/SPRINKLES WILL REMAIN POSSIBLE ACROSS THE NW
THIS AFTERNOON ASSOCIATED WITH COLD POOL ALOFT AND STEEPENING LAPSE
RATES. WE ALSO HAVE SOME WEAK H85-H7 FRONTOGENESIS LINGERING JUST TO
THE NORTHWEST OF THE CWA...RESPONSIBLE FOR CURRENT SHOWER ACTIVITY
OUTSIDE OF CWA. DO NOT ANTICIPATE ANY PRECIP LINGERING PAST SUNSET
WHEN DIURNAL HEATING COMES TO AN END.
COOLER AIR MASS ALREADY IN PLACE AFTER FRONTAL PASSAGE LAST
NIGHT...WITH H85 TEMPS BASED ON THIS MORNINGS 12Z SOUNDING IN THE
12-14C RANGE. WITH CALM WINDS AND CLEARING SKIES I EXPECT OVERNIGHT
TEMPS TO DROP TO THE LOW TO MID 40S ACROSS THE AREA. IF WE WERE TO
SEE LOWER TD VALUES ADVECT INTO THE CWA...THEN WE COULD BREAK A FEW
LOW TEMPERATURE RECORDS TONIGHT...WITH VALUES IN THE UPPER 30S.
PREVIOUS GUIDANCE WAS BRINGING MUCH LOWER TD VALUES INTO THE AREA
TONIGHT. HOWEVER...BASED ON UPSTREAM TRENDS AND CURRENT GUIDANCE TD
VALUES SHOULD REMAIN 40F OR HIGHER...WHICH WILL LIMIT COOLING
POTENTIAL.
.LONG TERM...(SATURDAY THROUGH FRIDAY)
ISSUED AT 226 PM MDT FRI SEP 7 2012
SATURDAY THROUGH SUNDAY NIGHT WILL REMAIN DRY AS THE UPPER LEVEL
RIDGE CURRENTLY OVER THE SOUTHERN CONUS BUILDS NORTHWARD OVER THE
GREAT BASIN AND EXPANDS EAST INTO THE PLAINS. SUNDAY AFTERNOON AND
SUNDAY NIGHT THE RIDGE WILL FLATTEN OUT AS A SHORT WAVE TROUGH MOVES
ACROSS IT. THE SHORT WAVE TROUGH WILL MOVE INTO THE AREA SUNDAY
NIGHT. HOWEVER AM ONLY EXPECTING SOME CLOUDS TO DEVELOP WITH THE
TROUGH DUE TO THE SHALLOW MOIST LAYER TO WORK WITH BETWEEN 500-600MB.
TUESDAY THROUGH FRIDAY WILL HAVE CHANCES FOR PRECIPITATION ALMOST
EVERY DAY. TUESDAY AN UPPER LEVEL SHORT WAVE TROUGH AND ASSOCIATED
SURFACE TROUGH MOVE ACROSS THE AREA PROVIDING AN OPPORTUNITY FOR
SOME LOCATIONS TO RECEIVE RAINFALL. TUESDAY NIGHT INTO WEDNESDAY
ANOTHER UPPER LEVEL SHORT WAVE TROUGH FOLLOWS A COLD FRONT THROUGH
THE AREA...OFFERING A SHOT FOR MORE WIDE SPREAD RAINFALL. THE NEXT
BEST CHANCE FOR WIDE SPREAD RAINFALL COMES WEDNESDAY NIGHT THROUGH THURSDAY
NIGHT AS AN UPPER LEVEL LONG WAVE TROUGH MOVES ACROSS THE PLAINS. THERE
MAY BE SOME LINGERING STORM ACTIVITY ON FRIDAY AS THE TROUGH DEPARTS
THE AREA. HIGH TEMPERATURES WILL BE WARMEST ON MONDAY AND TUESDAY AHEAD OF THE
COLD FRONT...ROUGHLY 10 DEGREES ABOVE NORMAL. FROM WEDNESDAY
THROUGH FRIDAY HIGH TEMPERATURES WILL BE ALMOST 10 DEGREES BELOW
NORMAL. LOW TEMPERATURES FOR THE PERIOD WILL BE NEAR NORMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1117 AM MDT FRI SEP 7 2012
VFR CONDITIONS WILL PREVAIL AT BOTH KGLD AND KMCK TERMINALS
THROUGH THE PERIOD. GUSTY NORTH WINDS WILL CONTINUE THROUGH AROUND
SUNSET AT BOTH TERMINALS...WITH GUSTS 20-25KT EXPECTED. VARIABLE
WINDS LESS THAN 10KT ARE THEN EXPECTED TO PREVAIL THROUGH THE
REMAINING TAF PERIOD AS SURFACE HIGH PRESSURE MOVES INTO THE
REGION.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...JTL
AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
211 PM MDT FRI SEP 7 2012
.SHORT TERM...(THIS AFTERNOON THROUGH TONIGHT)
ISSUED AT 210 PM MDT FRI SEP 7 2012
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW POSITIVELY TILTED TROUGH
OVER NORTHERN GREAT LAKES WITH AXIS EXTENDING SOUTHWEST ACROSS
CENTRAL NEBRASKA. LARGE SCALE SUBSIDE IS CURRENTLY BUILDING INTO
TRI-STATE AREA AS THIS TROUGH SHIFTS EAST. AT THE SURFACE HIGH
PRESSURE BUILDING INTO THE CWA FROM THE NORTHWEST.
ISOLATED LIGHT SHOWERS/SPRINKLES WILL REMAIN POSSIBLE ACROSS THE NW
THIS AFTERNOON ASSOCIATED WITH COLD POOL ALOFT AND STEEPENING LAPSE
RATES. WE ALSO HAVE SOME WEAK H85-H7 FRONTOGENESIS LINGERING JUST TO
THE NORTHWEST OF THE CWA...RESPONSIBLE FOR CURRENT SHOWER ACTIVITY
OUTSIDE OF CWA. DO NOT ANTICIPATE ANY PRECIP LINGERING PAST SUNSET
WHEN DIURNAL HEATING COMES TO AN END.
COOLER AIRMASS ALREADY IN PLACE AFTER FRONTAL PASSAGE LAST
NIGHT...WITH H85 TEMPS BASED ON THIS MORNINGS 12Z SOUNDING IN THE
12-14C RANGE. WITH CALM WINDS AND CLEARING SKIES I EXPECT OVERNIGHT
TEMPS TO DROP TO THE LOW TO MID 40S ACROSS THE AREA. IF WE WERE TO
SEE LOWER TD VALUES ADVECT INTO THE CWA...THEN WE COULD BREAK A FEW
LOW TEMPERATURE RECORDS TONIGHT...WITH VALUES IN THE UPPER 30S.
PREVIOUS GUIDANCE WAS BRINGING MUCH LOWER TD VALUES INTO THE AREA
TONIGHT. HOWEVER...BASED ON UPSTREAM TRENDS AND CURRENT GUIDANCE TD
VALUES SHOULD REMAIN 40F OR HIGHER...WHICH WILL LIMIT COOLING
POTENTIAL.
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 230 AM MDT FRI SEP 7 2012
SATURDAY NIGHT-SUNDAY NIGHT...H5 RIDGE WILL AMPLIFY DURING THE
PERIOD BEFORE BEGINNING TO FLATTEN BY SUNDAY NIGHT. WITH DRY AIR MASS
IN PLACE ACROSS THE AREA AND LOW LEVEL FLOW NOT REALLY FAVORABLE FOR
ANY MEANINGFUL MOISTURE RETURN SEE NO REASON WHY DRY CONDITIONS WILL
NOT CONTINUE TO PREVAIL THROUGH THE PERIOD. TEMPERATURES WILL WARM
THROUGH THE PERIOD WITH LOWS WARMING SEVERAL DEGREES FROM THE
PREVIOUS DAY ON SATURDAY AND AGAIN ON SUNDAY. HIGH TEMPERATURES WILL
ALSO WARM THROUGH THE PERIOD WITH MID 80S TO LOW 90S POSSIBLE BY
SUNDAY.
WARMER TEMPERATURES WILL RETURN BY EARLY NEXT WEEK AS THE SURFACE HIGH
SLIDES EAST INTO THE MISSISSIPPI AND OHIO RIVER VALLEYS AND A BROAD
RIDGE BUILDS INTO THE CENTRAL PORTION OF THE COUNTRY. THE RIDGE WILL
CONTINUE TO SHIFT EASTWARD TOWARDS THE ATLANTIC COAST AS A VIGOROUS
TROUGH SWINGS ACROSS THE CANADIAN AND NORTH CENTRAL PLAINS. THE
ATTENDANT COLD FRONT WILL MOVE ACROSS THE REGION TUESDAY AFTERNOON
AND EVENING WITH THE CHANCE OF SCATTERED THUNDERSTORMS DEVELOPING AS
IT MOVES THROUGH. THERE IS A CHANCE THAT A FEW SHOWERS MAY
LINGER INTO WEDNESDAY MORNING. ANOTHER CHANCE FOR SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE LATE WEDNESDAY AFTERNOON AS
A SHORTWAVE TROUGH MOVING THROUGH THE FLOW IMPACTS THE AREA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1117 AM MDT FRI SEP 7 2012
VFR CONDITIONS WILL PREVAIL AT BOTH KGLD AND KMCK TERMINALS
THROUGH THE PERIOD. GUSTY NORTH WINDS WILL CONTINUE THROUGH AROUND
SUNSET AT BOTH TERMINALS...WITH GUSTS 20-25KT EXPECTED. VARIABLE
WINDS LESS THAN 10KT ARE THEN EXPECTED TO PREVAIL THROUGH THE
REMAINING TAF PERIOD AS SURFACE HIGH PRESSURE MOVES INTO THE
REGION.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...JRM/PMM
AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1059 PM MDT THU SEP 6 2012
.UPDATE...
ISSUED AT 1004 PM MDT THU SEP 6 2012
UPDATE DUE TO EXPIRATION OF WATCH. ALSO MADE MINOR ADJUSTMENTS ON
REMAINING HOURLY GRIDS.
UPDATE ISSUED AT 828 PM MDT THU SEP 6 2012
JUST COMPLETED ANOTHER UPDATE. TRIMMED OFF ALL BUT THE EASTERN
PORTION OF THE WATCH AND COULD HAVE TRIMMED IT ALL BUT JUST ENOUGH
THERE FOR ME TO KEEP IT IN UNTIL 04Z. LOOKING THE UPSTREAM 00Z
SOUNDING IT DOES NOT LOOK FAVORABLE FOR REDEVELOPMENT WITH A DRY
AIR MASS IN PLACE. MID LEVEL MOISTURE DOES INCREASE AFTER 06Z.
MODELS INSIST ON KEEPING A CONSIDERABLE AMOUNT OF ELEVATED CAPE
INTO TOMORROW MORNING WITH LOW CINH UNTIL AFTER 12Z.
LIGHTNING DETECTION NETWORK IS SHOWING SOME INCREASE IN LIGHTING
WELL TO THE NORTHWEST AND ESPECIALLY WEST AS A RATHER STRONGER
SHORTWAVE TROUGH MOVES IN. ALSO AREA COMES UNDER THE INFLUENCE OF
RIGHT REAR QUADRANT OF THE JET BY LATE TONIGHT INTO TOMORROW
MORNING. AM NOT VERY EXCITED ABOUT THE PROSPECT OF MEASURABLE BUT
CANNOT IGNORE WHAT IS GOING ON UPSTREAM COMBINED WITH WHAT THE
LIFT AND INSTABILITY IS SHOWING ME. SO AFTER AFTER THE WATCH IS
OVER KEPT A SLIGHT CHANCE TO LOW CHANCE OF PRECIPITATION INTO
TOMORROW MORNING.
AT THIS TIME IT LOOKS LIKE WILL STAY BELOW WIND ADVISORY CRITERIA
BUT WILL CONTINUE TO MONITOR TRENDS AND NEWER DATA.
UPDATE ISSUED AT 629 PM MDT THU SEP 6 2012
JUST COMPLETED AN UPDATE MAINLY TO REFINE THUNDERSTORM FORECAST.
MAIN LINE OF THUNDERSTORMS HAS PUSHED OFF TO THE EAST OF THE
FORECAST AREA AT THIS TIME. BOUNDARY IS STILL OVER THE AREA THAT
IS IN THE SEVERE THUNDERSTORM WATCH WITH IT PROGGED TO MOVE BACK
TO THE WEST THIS EVENING. PROBLEM AT THIS TIME...MAIN MID/UPR
LEVEL SUPPORT HAS PUSHED OFF TO THE EAST. AM VERY PESSIMISTIC
ABOUT ANY REDEVELOPMENT AT THIS TIME. HOWEVER...WILL CONTINUE TO
WATCH TRENDS AND ALLOW NEWER MODEL DATA TO COME IN.
SO AT THIS TIME...REDUCED POPS AND REDUCED AREA OF PRECIPITATION.
ALSO REDUCED TH SKY COVER AS WELL BECAUSE OF THIS. WIND FIELD IS
ALL OVER THE PLACE DUE TO THE ABOVE MENTIONED BOUNDARY AND AS A
RESULT MODELS HAVING A HARD TIME IN RESOLVING THE DEWPOINT FIELD
AS WELL. LOWER DEWPOINTS ARE MUCH FURTHER EAST BUT SHOULD COME
BACK TO WEST THROUGH THE EVENING. FRONT STILL LOOKS ON TRACK IN
THE NORTH AROUND 06Z. DEFINITELY NOT THE LAST UPDATE FOR THE
EVENING.
UPDATE ISSUED AT 259 PM MDT THU SEP 6 2012
UPDATED FORECAST TO INCLUDE THE SEVERE THUNDERSTORM WATCH THIS
AFTERNOON AND EVENING.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 149 PM MDT THU SEP 6 2012
LATEST WV IMAGERY AND RUC H5 ANALYSIS CONTINUE TO INDICATE WESTERLY
FLOW ACROSS THE INTER-MOUNTAIN WEST AND HIGH PLAINS JUST NORTH OF
SOUTHWESTERN CONUS RIDGE. AT THE SURFACE A TROUGH/DRY LINE HAS
SHIFTED EAST TO LIE FROM JUST WEST OF MCCOOK NEBRASKA...BETWEEN
GOODLAND AND COLBY KANSAS...AND THEN WEST OF TRIBUNE KANSAS. TD
VALUES IN THE UPPER 50S/LOW 60S AND MIXED LAYER CAPES IN EXCESS OF
1000 J/KG ARE CURRENTLY EAST OF THIS DRY LINE...WITH MUCH MORE
STABLE AIR MASS TO THE WEST OF THIS FEATURE.
SURFACE CONVERGENCE AHEAD OF THIS DRY LINE SHOULD HELP OVERCOME
WEAKENING CAP LATER THIS AFTERNOON AND EARLY THIS EVENING...WITH
THUNDERSTORM COVERAGE INCREASING FURTHER EAST WHERE BETTER LARGE
SCALE FORCING IS EXPECTED. BASED ON MODEL SOUNDINGS LCL VALUES
REMAIN HIGH...WITH DEEP MIXED LAYER TO ABOUT 650 MB INDICATIVE OF
MICROBURST POTENTIAL WITH THUNDERSTORMS. IN ADDITION...SUPERCELL
THUNDERSTORMS WILL BE A POSSIBILITY....WITH 0-6KM BULK SHEAR VALUES
PROGGED TO BE AROUND 40KT OR HIGHER...AND WITH MIXED LAYER CAPE IN
EXCESS OF 1500 J/KG. LCL VALUES WILL BE FAIRLY HIGH IN THE 8-10KFT
RANGE...SO IM NOT AS CONCERNED ABOUT A TORNADO THREAT WITH THIS
ACTIVITY.
A COLD FRONT IS EXPECTED TO MOVE ACROSS THE CWA FROM THE NW AFTER
MIDNIGHT...WITH LARGE PRESSURE RISES AND INCREASING H85 WINDS BEHIND
THE FRONT POSSIBLY RESULTING IN ADVISORY CRITERIA WINDS. OTHER THAN
THE 12Z NAM...MOST GUIDANCE IS VERY MARGINAL ON THIS...SO I DECIDED
AGAINST ISSUING AN ADVISORY THIS FORECAST CYCLE. AHEAD OF THIS FRONT
ELEVATED INSTABILITY AND MOISTURE WILL BEGIN TO BUILD BACK TO THE
WEST...WITH ISOLATED THREAT FOR CONVECTION RETURNING AFTER MIDNIGHT
THROUGH FRIDAY MORNING AS THE FRONT MOVES ACROSS THE REGION.
CONFIDENCE IS LOW AT THIS TIME...AND MOST GUIDANCE IS NOT CURRENTLY
INITIATING ANYTHING WITH THIS FROPA...SO I LIMITED POPS TO SLIGHT
CHANCE CATEGORY. LARGE SCALE SUBSIDENCE SHOULD BRING DRY CONDITIONS
BACK TO THE CWA FRIDAY.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 215 PM MDT THU SEP 6 2012
DRY AND MILD CONDITIONS ON FRIDAY NIGHT AND SATURDAY WILL
TRANSITION TO DRY AND WARM CONDITIONS DURING THE FIRST PART OF
NEXT WEEK AS THE UPPER RIDGE MOVES FROM THE ROCKIES TO THE HIGH
PLAINS AND THE COOLER AREA OF HIGH PRESSURE AT THE SURFACE SLIDES
INTO THE SOUTHERN PLAINS. SOUTHERLY SURFACE RETURN FLOW
ESTABLISHES OVER THE CENTRAL HIGH PLAINS ON SUNDAY AND CONTINUES
THROUGH MONDAY AS THE SURFACE LEE TROUGH DEEPENS AND THE UPPER
RIDGE TRANSITIONS OVER THE PLAINS STATES. TEMPERATURES ARE
EXPECTED TO WARM BACK UP INTO THE 90S BY MONDAY AS A RESULT AHEAD
OF THE NEXT FRONT DUE THROUGH THE REGION DURING THE DAY ON TUESDAY.
ISOLATED TO SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP ON
TUESDAY IN THE VICINITY OF THE FRONT. STORMS WILL BECOME MORE
WIDESPREAD AND CONTINUE THROUGH TUESDAY NIGHT AND INTO WEDNESDAY
AS THE FLOW OVER THE CENTRAL HIGH PLAINS BECOMES MORE ZONAL AND A
SERIES OF SHORT WAVE TROUGHS MOVES THROUGH THE FLOW.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1055 PM MDT THU SEP 6 2012
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. IT LOOKS LIKE THE
BEST CHANCE FOR PRECIPITATION WILL BE TO THE EAST OF BOTH TAF
SITES SO LEFT ALL MENTION OUT. COLD FRONT IS BEGINNING TO MOVE
THROUGH THE AREA AT THIS TIME. NORTH WINDS WILL BE GUSTY THROUGH
THE DAY WITH THE HIGHEST SPEEDS/GUSTS THROUGH EARLY IN THE AFTERNOON.
AFTER THAT WINDS WILL BECOME MUCH LIGHTER.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...BULLER
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1005 PM MDT THU SEP 6 2012
.UPDATE...
ISSUED AT 1004 PM MDT THU SEP 6 2012
UPDATE DUE TO EXPIRATION OF WATCH. ALSO MADE MINOR ADJUSTMENTS ON
REMAINING HOURLY GRIDS.
UPDATE ISSUED AT 828 PM MDT THU SEP 6 2012
JUST COMPLETED ANOTHER UPDATE. TRIMMED OFF ALL BUT THE EASTERN
PORTION OF THE WATCH AND COULD HAVE TRIMMED IT ALL BUT JUST ENOUGH
THERE FOR ME TO KEEP IT IN UNTIL 04Z. LOOKING THE UPSTREAM 00Z
SOUNDING IT DOES NOT LOOK FAVORABLE FOR REDEVELOPMENT WITH A DRY
AIR MASS IN PLACE. MID LEVEL MOISTURE DOES INCREASE AFTER 06Z.
MODELS INSIST ON KEEPING A CONSIDERABLE AMOUNT OF ELEVATED CAPE
INTO TOMORROW MORNING WITH LOW CINH UNTIL AFTER 12Z.
LIGHTNING DETECTION NETWORK IS SHOWING SOME INCREASE IN LIGHTING
WELL TO THE NORTHWEST AND ESPECIALLY WEST AS A RATHER STRONGER
SHORTWAVE TROUGH MOVES IN. ALSO AREA COMES UNDER THE INFLUENCE OF
RIGHT REAR QUADRANT OF THE JET BY LATE TONIGHT INTO TOMORROW
MORNING. AM NOT VERY EXCITED ABOUT THE PROSPECT OF MEASURABLE BUT
CANNOT IGNORE WHAT IS GOING ON UPSTREAM COMBINED WITH WHAT THE
LIFT AND INSTABILITY IS SHOWING ME. SO AFTER AFTER THE WATCH IS
OVER KEPT A SLIGHT CHANCE TO LOW CHANCE OF PRECIPITATION INTO
TOMORROW MORNING.
AT THIS TIME IT LOOKS LIKE WILL STAY BELOW WIND ADVISORY CRITERIA
BUT WILL CONTINUE TO MONITOR TRENDS AND NEWER DATA.
UPDATE ISSUED AT 629 PM MDT THU SEP 6 2012
JUST COMPLETED AN UPDATE MAINLY TO REFINE THUNDERSTORM FORECAST.
MAIN LINE OF THUNDERSTORMS HAS PUSHED OFF TO THE EAST OF THE
FORECAST AREA AT THIS TIME. BOUNDARY IS STILL OVER THE AREA THAT
IS IN THE SEVERE THUNDERSTORM WATCH WITH IT PROGGED TO MOVE BACK
TO THE WEST THIS EVENING. PROBLEM AT THIS TIME...MAIN MID/UPR
LEVEL SUPPORT HAS PUSHED OFF TO THE EAST. AM VERY PESSIMISTIC
ABOUT ANY REDEVELOPMENT AT THIS TIME. HOWEVER...WILL CONTINUE TO
WATCH TRENDS AND ALLOW NEWER MODEL DATA TO COME IN.
SO AT THIS TIME...REDUCED POPS AND REDUCED AREA OF PRECIPITATION.
ALSO REDUCED TH SKY COVER AS WELL BECAUSE OF THIS. WIND FIELD IS
ALL OVER THE PLACE DUE TO THE ABOVE MENTIONED BOUNDARY AND AS A
RESULT MODELS HAVING A HARD TIME IN RESOLVING THE DEWPOINT FIELD
AS WELL. LOWER DEWPOINTS ARE MUCH FURTHER EAST BUT SHOULD COME
BACK TO WEST THROUGH THE EVENING. FRONT STILL LOOKS ON TRACK IN
THE NORTH AROUND 06Z. DEFINITELY NOT THE LAST UPDATE FOR THE
EVENING.
UPDATE ISSUED AT 259 PM MDT THU SEP 6 2012
UPDATED FORECAST TO INCLUDE THE SEVERE THUNDERSTORM WATCH THIS
AFTERNOON AND EVENING.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 149 PM MDT THU SEP 6 2012
LATEST WV IMAGERY AND RUC H5 ANALYSIS CONTINUE TO INDICATE WESTERLY
FLOW ACROSS THE INTER-MOUNTAIN WEST AND HIGH PLAINS JUST NORTH OF
SOUTHWESTERN CONUS RIDGE. AT THE SURFACE A TROUGH/DRY LINE HAS
SHIFTED EAST TO LIE FROM JUST WEST OF MCCOOK NEBRASKA...BETWEEN
GOODLAND AND COLBY KANSAS...AND THEN WEST OF TRIBUNE KANSAS. TD
VALUES IN THE UPPER 50S/LOW 60S AND MIXED LAYER CAPES IN EXCESS OF
1000 J/KG ARE CURRENTLY EAST OF THIS DRY LINE...WITH MUCH MORE
STABLE AIR MASS TO THE WEST OF THIS FEATURE.
SURFACE CONVERGENCE AHEAD OF THIS DRY LINE SHOULD HELP OVERCOME
WEAKENING CAP LATER THIS AFTERNOON AND EARLY THIS EVENING...WITH
THUNDERSTORM COVERAGE INCREASING FURTHER EAST WHERE BETTER LARGE
SCALE FORCING IS EXPECTED. BASED ON MODEL SOUNDINGS LCL VALUES
REMAIN HIGH...WITH DEEP MIXED LAYER TO ABOUT 650 MB INDICATIVE OF
MICROBURST POTENTIAL WITH THUNDERSTORMS. IN ADDITION...SUPERCELL
THUNDERSTORMS WILL BE A POSSIBILITY....WITH 0-6KM BULK SHEAR VALUES
PROGGED TO BE AROUND 40KT OR HIGHER...AND WITH MIXED LAYER CAPE IN
EXCESS OF 1500 J/KG. LCL VALUES WILL BE FAIRLY HIGH IN THE 8-10KFT
RANGE...SO IM NOT AS CONCERNED ABOUT A TORNADO THREAT WITH THIS
ACTIVITY.
A COLD FRONT IS EXPECTED TO MOVE ACROSS THE CWA FROM THE NW AFTER
MIDNIGHT...WITH LARGE PRESSURE RISES AND INCREASING H85 WINDS BEHIND
THE FRONT POSSIBLY RESULTING IN ADVISORY CRITERIA WINDS. OTHER THAN
THE 12Z NAM...MOST GUIDANCE IS VERY MARGINAL ON THIS...SO I DECIDED
AGAINST ISSUING AN ADVISORY THIS FORECAST CYCLE. AHEAD OF THIS FRONT
ELEVATED INSTABILITY AND MOISTURE WILL BEGIN TO BUILD BACK TO THE
WEST...WITH ISOLATED THREAT FOR CONVECTION RETURNING AFTER MIDNIGHT
THROUGH FRIDAY MORNING AS THE FRONT MOVES ACROSS THE REGION.
CONFIDENCE IS LOW AT THIS TIME...AND MOST GUIDANCE IS NOT CURRENTLY
INITIATING ANYTHING WITH THIS FROPA...SO I LIMITED POPS TO SLIGHT
CHANCE CATEGORY. LARGE SCALE SUBSIDENCE SHOULD BRING DRY CONDITIONS
BACK TO THE CWA FRIDAY.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 215 PM MDT THU SEP 6 2012
DRY AND MILD CONDITIONS ON FRIDAY NIGHT AND SATURDAY WILL
TRANSITION TO DRY AND WARM CONDITIONS DURING THE FIRST PART OF
NEXT WEEK AS THE UPPER RIDGE MOVES FROM THE ROCKIES TO THE HIGH
PLAINS AND THE COOLER AREA OF HIGH PRESSURE AT THE SURFACE SLIDES
INTO THE SOUTHERN PLAINS. SOUTHERLY SURFACE RETURN FLOW
ESTABLISHES OVER THE CENTRAL HIGH PLAINS ON SUNDAY AND CONTINUES
THROUGH MONDAY AS THE SURFACE LEE TROUGH DEEPENS AND THE UPPER
RIDGE TRANSITIONS OVER THE PLAINS STATES. TEMPERATURES ARE
EXPECTED TO WARM BACK UP INTO THE 90S BY MONDAY AS A RESULT AHEAD
OF THE NEXT FRONT DUE THROUGH THE REGION DURING THE DAY ON TUESDAY.
ISOLATED TO SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP ON
TUESDAY IN THE VICINITY OF THE FRONT. STORMS WILL BECOME MORE
WIDESPREAD AND CONTINUE THROUGH TUESDAY NIGHT AND INTO WEDNESDAY
AS THE FLOW OVER THE CENTRAL HIGH PLAINS BECOMES MORE ZONAL AND A
SERIES OF SHORT WAVE TROUGHS MOVES THROUGH THE FLOW.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 540 PM MDT THU SEP 6 2012
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. AT THIS TIME
INITIAL ROUND OF THUNDERSTORMS WILL BE TO THE EAST OF BOTH TAF
SITES. THERE IS A LOW PROBABILITY OF THUNDERSTORMS AFTER 06Z BUT
AT THIS TIME TO KEEP THEM OUT. WILL CONTINUE TO MONITOR CLOSELY
WITH LATEST DATA FOR POSSIBLE UPDATES. STRONG COLD FRONT BEGINS TO
MOVE THROUGH THE AREA IN THE 06Z TO 08Z TIME FRAME WITH VERY GUSTY
WINDS EXPECTED THROUGH THE MORNING HOURS. AFTER THAT WINDS WILL
BEGIN TO GRADUALLY DECREASE.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...BULLER
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1248 PM CDT FRI SEP 7 2012
.NEAR TERM...(THIS AFTERNOON AND TONIGHT)
ISSUED AT 1248 PM CDT FRI SEP 7 2012
SOME OF THE DISCUSSION BELOW IS FROM AN UPDATE AT 1141 AM.
UPDATED SKY FORECAST...AS IT WAS TOO PESSIMISTIC. NAM TEMPS ALSO
QUITE A WAYS OFF. SIDED WITH WARMER GFS MOS NUMBERS AND BLENDED
THEM WITH OUR EXISTING NUMBERS. CONVECTION HAS BEEN WEAK OVER
SOUTHERN ILLINOIS THIS MORNING. THERE IS NEWLY DEVELOPED
CONVECTION ALONG A BOUNDARY JUST NORTH OF OUR CWFA...BUT IT
APPEARS TO BE HEADING OFF TO THE EAST. HERE IS THE LATEST THINKING
ON THE SEVERE WEATHER / THUNDERSTORM SCENARIO THIS AFTERNOON AND
EVENING.
FIRST...LOOKING AS VISIBLE IMAGERY...AND H5 ANALYSIS...HARD TO
SAY WHAT THE FOCUS WILL BE EARLY ON. THAT MEANS OUR CONFIDENCE IN
THE MESO SCALE MODELS IS LOW AT BEST. HINTS OF ELEVATED INSTABILITY
PER ACCAS AND ENHANCED CLOUDS ON VISIBLE...BUT VERY WEAK FORCING
ACROSS THE AREA. THE HRRR SUGGESTS THAT SUPPORT AND ASSOC CONVECTION
SOUTH OF JOPLIN COULD ORGANIZE WITH TIME AND HEAD EAST ACROSS
SOUTHERN MISSOURI...MAYBE EVEN REACHING WESTERN KENTUCKY BY EARLY
EVENING. THIS MAY NOT BE TOO UNREASONABLE...GIVEN THE MODELS
GENERATE DECENT INSTABILITY INTO SOUTHERN AND SOUTHEAST MISSOURI
THIS AFTERNOON. WILL MONITOR THIS. THEN OF COURSE YOU HAVE THE
FRONT COMING IN FROM THE NORTHWEST WHICH THE HRRR HAS FROM ECNTRL
IL TO NEAR KSTL INTO SW MISSOURI AROUND 00Z. CONVECTION IS LINED
OUT ALONG THE FRONT AS WELL...ALONG AND JUST BEHIND IT.
WE HAVE NEW POP GRIDS...TAILORED TOWARD THE POSSIBILITY OF
CONVECTION COMING IN FROM THE WEST INTO SOUTHEAST MISSOURI...AND
IN FROM THE NORTHWEST WITH THE FRONT. BEST WE CAN DO GIVEN THE
LOWER CONFIDENCE IN THE MESOSCALE MODELS.
AS FAR AS SEVERE TYPE. NOT MUCH DIFFERENCE IN AIRMASS. MAIN
DIFFERENCE SYNOPTICALLY IS A STRONG FRONT MOVING INTO THE
AREA...AND ANY ADDITIONAL MESOSCALE BOUNDARIES AHEAD OF IT
CONVECTION CAN ACT UPON. GIVEN THE DEGREE OF FORECAST POTENTIAL
INSTABILITY AND AMOUNT OF LOW LEVEL MOISTURE...SEVERE WINDS
SEEMS TO BE THE MAIN HAZARD...ESPECIALLY SHOULD ANY CLUSTERS
BECOME SELF SUSTAINING AND ORGANIZED. FREEZING LEVELS ARE SLIGHTLY
LOWER...SO A MARGINAL SEVERE HAIL THREAT IS IN PLAY. TORNADIC
POSSIBILITY SHOULD BE LOW GIVEN LACK OF SUBSTANTIAL WIND FIELDS.
CANNOT RULE OUT THE PESKY SPIN UPS WHERE NEAR STORM RELATIVE FLOW
ENVIRONMENT MAY SEE ENHANCED SHEAR.
TONIGHT...BEST CHANCE POPS FROM 03Z THROUGH 09Z AS THE FRONT MOVES
STEADILY FROM NW TO SE ACROSS THE AREA. WIDESPREAD COVERAGE EXPECTED
SO BUMPED UP POPS TO NEAR 100 PERCENT...WITH SOME AREAS LIKELY
RECEIVING 1-2 INCHES OF RAINFALL. ENDING PRECIPITATION WILL FOLLOW
ESPECIALLY FROM SOUTHERN ILLINOIS INTO SOUTHEAST MISSOURI.
STAY TUNED...PROBABILITY OF A WATCH OF SOME KIND IS LIKELY HIGH
GIVEN SPC/S SEVERE WEATHER PROBABILITIES.
.SHORT/LONG TERM...(SATURDAY THROUGH FRIDAY)
ISSUED AT 1248 PM CDT FRI SEP 7 2012
THIS PERIOD WILL START WITH THE MEAN TROUGH ALONG AND JUST EAST OF
THE WFO PAH FORECAST AREA. THIS WILL ALLOW COLD AIR ADVECTION TO
CONTINUE THROUGH THE DAYTIME HOURS SATURDAY...WITH THE GRADIENT
WEAKENING SATURDAY NIGHT. BELOW NORMAL TEMPERATURES /10-15 DEGREES
BELOW NORMAL/ CAN BE EXPECTED SATURDAY...SLOWLY MODERATING INTO
EARLY NEXT WEEK AS LOW AMPLITUDE RIDGING PUSHES ACROSS THE CENTRAL
UNITED STATES. THIS RIDGE WILL TAKE MOST OF THE WEEK TO PUSH EAST OF
THE WFO PAH FORECAST AREA...SO THERE WILL BE A SLOW BUT GRADUAL RISE
IN DAILY TEMPERATURES INTO THE MIDDLE 80S...PRIMARILY DOMINATED BY
DIURNAL TRENDS...MAINLY SUNSHINE...GIVEN MINIMAL CLOUD COVER
EXPECTED THROUGH NEXT WEEK.
THE GFS ATTEMPTS TO MOVE A FRONT CLOSE THE THE NORTHWEST SECTIONS OF
THE WFO PAH FORECAST AREA BY LATE NEXT FRIDAY. GIVEN THE UNCERTAINTY
DUE TO THE TIMING OF THIS SYSTEM...WILL KEEP THE FORECAST DRY
THROUGH ALL OF NEXT WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY)
ISSUED AT 1141 AM CDT FRI SEP 7 2012
CONFIDENCE IN CONVECTION IS LOW THROUGH LATE AFTERNOON. HOWEVER
CONFIDENCE INCREASES LATE AFTERNOON INTO FIRST PART OF TONIGHT AS
A STRONG COLD FRONT PUSHES SOUTH ACROSS THE REGION. WILL NOT
DEVIATE MUCH FROM CURRENT TAFS AND INDICATE DECENT PROBABILITIES
FOR CONVECTION AFTER 21-23Z...EVEN BEHIND THE FRONT...AS THE
MODELS INDICATE POST FRONTAL CONVECTION LIKELY AS WELL. BEST
CHANCE TIME FRAME FOR BROAD SCALE COVERAGE IS 03Z-09Z. BY
12Z...THE AREA SHOULD BE CLEAR OF CONVECTION. CHANCE OF STRONG TO
SEVERE STORMS IS STILL IN PLAY AS WELL THIS AFTERNOON AND EVENING.
DAMAGING WINDS APPEAR TO BE THE MAIN HAZARD. VISIBILITY
RESTRICTIONS DUE TO HEAVY RAIN LIKELY AT THE TAF SITES AT SOME
POINT ALONG WITH LOW END MVFR TO IFR CONDITIONS.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
NEAR TERM/AVIATION...NOLES
SHORT/LONG TERM....SMITH
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1141 AM CDT FRI SEP 7 2012
.UPDATE...
ISSUED AT 1141 AM CDT FRI SEP 7 2012
UPDATED TO INCLUDE NEAR TERM DISCUSSION SECTION. UPDATED THE
AVIATION SECTION.
&&
.NEAR TERM...(REST OF TODAY)
ISSUED AT 1141 AM CDT FRI SEP 7 2012
UPDATED SKY FORECAST...AS IT WAS TOO PESSIMISTIC. NAM TEMPS ALSO
QUITE A WAYS OFF. SIDED WITH WARMER GFS MOS NUMBERS AND BLENDED
THEM WITH OUR EXISTING NUMBERS. CONVECTION HAS BEEN WEAK OVER
SOUTHERN ILLINOIS THIS MORNING. THERE IS NEWLY DEVELOPED
CONVECTION ALONG A BOUNDARY JUST NORTH OF OUR CWFA...BUT IT
APPEARS TO BE HEADING OFF TO THE EAST. HERE IS THE LATEST THINKING
ON THE SEVERE WEATHER / THUNDERSTORM SCENARIO THIS AFTERNOON AND
EVENING.
FIRST...LOOKING AS VISIBLE IMAGERY...AND H5 ANALYSIS...HARD TO
SAY WHAT THE FOCUS WILL BE EARLY ON. THAT MEANS OUR CONFIDENCE IN
THE MESO SCALE MODELS IS LOW AT BEST. HINTS OF ELEVATED INSTABILITY
PER ACCAS AND ENHANCED CLOUDS ON VISIBLE...BUT VERY WEAK FORCING
ACROSS THE AREA. THE HRRR SUGGESTS THAT SUPPORT AND ASSOC CONVECTION
SOUTH OF JOPLIN COULD ORGANIZE WITH TIME AND HEAD EAST ACROSS
SOUTHERN MISSOURI...MAYBE EVEN REACHING WESTERN KENTUCKY BY EARLY
EVENING. THIS MAY NOT BE TOO UNREASONABLE...GIVEN THE MODELS
GENERATE DECENT INSTABILITY INTO SOUTHERN AND SOUTHEAST MISSOURI
THIS AFTERNOON. WILL MONITOR THIS. THEN OF COURSE YOU HAVE THE
FRONT COMING IN FROM THE NORTHWEST WHICH THE HRRR HAS FROM ECNTRL
IL TO NEAR KSTL INTO SW MISSOURI AROUND 00Z. CONVECTION IS LINED
OUT ALONG THE FRONT AS WELL...ALONG AND JUST BEHIND IT.
WE HAVE NEW POP GRIDS...TAILORED TOWARD THE POSSIBILITY OF
CONVECTION COMING IN FROM THE WEST INTO SOUTHEAST MISSOURI...AND
IN FROM THE NORTHWEST WITH THE FRONT. BEST WE CAN DO GIVEN THE
LOWER CONFIDENCE IN THE MESOSCALE MODELS.
AS FAR AS SEVERE TYPE. NOT MUCH DIFFERENCE IN AIRMASS. MAIN
DIFFERENCE SYNOPTICALLY IS A STRONG FRONT MOVING INTO THE
AREA...AND ANY ADDITIONAL MESOSCALE BOUNDARIES AHEAD OF IT
CONVECTION CAN ACT UPON. GIVEN THE DEGREE OF FORECAST POTENTIAL
INSTABILITY AND AMOUNT OF LOW LEVEL MOISTURE...SEVERE WINDS
SEEMS TO BE THE MAIN HAZARD...ESPECIALLY SHOULD ANY CLUSTERS
BECOME SELF SUSTAINING AND ORGANIZED. FREEZING LEVELS ARE SLIGHTLY
LOWER...SO A MARGINAL SEVERE HAIL THREAT IS IN PLAY. TORNADIC
POSSIBILITY SHOULD BE LOW GIVEN LACK OF SUBSTANTIAL WIND FIELDS.
CANNOT RULE OUT THE PESKY SPIN UPS WHERE NEAR STORM RELATIVE FLOW
ENVIRONMENT MAY SEE ENHANCED SHEAR.
STAY TUNED...PROBABILITY OF A WATCH OF SOME KIND IS LIKELY HIGH
GIVEN SPC/S SEVERE WEATHER PROBABILITIES.
&&
.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 149 AM CDT FRI SEP 7 2012
RISK WILL SUBSIDE BY 06Z AS LOSS OF DIURNAL FUEL SAPS SURFACE
BASED INSTABILITY AND PCPN BECOMES MORE POST FRONTAL. POPS PEAK AT
THIS STAGE WITH FROPA AND JUST BEHIND IT. HEALTHY PW`S MEAN
ANOTHER SUBSTANTIAL RAIN FOR THE AREA WITH CATEGORICAL POPS AND
MEAN AVERAGE QPF OF AROUND 2 INCHES. LOCALLY HIGHER AMOUNTS WILL
BE POSSIBLE.
THE 00Z MODELS TODAY SUPPORT WHAT THEY DID YESTERDAY...WHICH IS
USHER THE FRONT/PCPN THRU AND END IT BY 12Z. WE`VE LEANED THE
FORECAST AGAIN IN THIS DIRECTION WITH JUST A SLIGHT SPILLOVER
SMALL EARLY AM POP IN THE SE ONLY SATURDAY.
AFTER THAT IT`S DISTINCTLY DRIER/COOLER AIR WORKING IN BEHIND THE
FRONT TO MAKE FOR A PLEASANT WEEKEND WITH LIGHT NORTHERLIES.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 149 AM CDT FRI SEP 7 2012
GFS AND ECMWF CONTINUE TO SHOW HIGH PRESSURE OVER THE EASTERN U.S.
THROUGH MID WEEK...WITH THE CENTER OF THE HIGH SLIDING EAST OF THE
PAH FORECAST AREA MONDAY NIGHT INTO TUESDAY. VERY DRY AND
UNSEASONABLY COOL AIR WILL REMAIN OVER THE REGION MONDAY DUE TO
NORTH TO NORTHEAST WINDS...WITH TEMPERATURES 5 TO 10 DEGREES BELOW
SEASONAL NORMALS. A RETURN OF SOUTHERLY FLOW TUESDAY WILL LEAD TO A
WARM UP AND INCREASING DEW POINTS TUESDAY THROUGH THURSDAY...WITH
TEMPERATURES BACK TO SEASONAL READINGS FOR WEDNESDAY AND
THURSDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY)
ISSUED AT 1141 AM CDT FRI SEP 7 2012
CONFIDENCE IN CONVECTION IS LOW THROUGH LATE AFTERNOON. HOWEVER
CONFIDENCE INCREASES LATE AFTERNOON INTO FIRST PART OF TONIGHT AS
A STRONG COLD FRONT PUSHES SOUTH ACROSS THE REGION. WILL NOT
DEVIATE MUCH FROM CURRENT TAFS AND INDICATE DECENT PROBABILITIES
FOR CONVECTION AFTER 21-23Z...EVEN BEHIND THE FRONT...AS THE
MODELS INDICATE POST FRONTAL CONVECTION LIKELY AS WELL. BEST
CHANCE TIME FRAME FOR BROAD SCALE COVERAGE IS 03Z-09Z. BY
12Z...THE AREA SHOULD BE CLEAR OF CONVECTION. CHANCE OF STRONG TO
SEVERE STORMS IS STILL IN PLAY AS WELL THIS AFTERNOON AND EVENING.
DAMAGING WINDS APPEAR TO BE THE MAIN HAZARD. VISIBILITY
RESTRICTIONS DUE TO HEAVY RAIN LIKELY AT THE TAF SITES AT SOME
POINT ALONG WITH LOW END MVFR TO IFR CONDITIONS.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
UPDATE/NEAR TERM/AVIATION...NOLES
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
757 PM EDT SAT SEP 8 2012
.SYNOPSIS...
ISSUED AT 252 PM EDT SAT SEP 8 2012
EXPECT SHOWERS AND ISOLATED THUNDERSTORMS NEAR LAKE MICHIGAN
TONIGHT. THAT ACTIVITY WILL DIMINISH BY MID MORNING SUNDAY.
OTHERWISE EXPECT COOLER WEATHER TO PREVAIL INTO THE BEGINNING OF
THE WEEK. A WARMING TREND WILL BEGIN BY TUESDAY THAT WILL LAST
INTO THE END OF THE WEEK.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 252 PM EDT SAT SEP 8 2012
THE PRIMARY FORECAST CONCERN IS THE AREA OF SHOWERS MOVING
SOUTHEAST FROM WESTERN UPPER MICHIGAN AND HOW IT WILL IMPACT
SOUTHWEST LOWER MICHIGAN OVERNIGHT AS IT MOVES THROUGH.
OTHERWISE...I EXPECT TEMPERATURES TO FALL INTO THE 30S NEAR ROUTE
10 EAST OF THE LAKE SHORE SUNDAY NIGHT. AN EARLY TASTE OF FALL FOR
SURE.
A STRONG SHORTWAVE... WELL DEFINED ON THE WATER VAPOR LOOPS...
WILL CONTINUE TO DROP SOUTHEAST CROSSING SOUTHWEST LOWER MICHIGAN
DURING THE EARLY EVENING HOURS. THERE IS A 130 KNOT JET EXIT
REGION THAT CROSSES SOUTHERN LAKE MICHIGAN JUST BEFORE MIDNIGHT
ASSOCIATED WITH FEATURE. THIS JET CORE IS ROTATING AROUND THE BASE
OF THE CLOSED 300 MB LOW THAT IS ALSO ASSOCIATED WITH THIS
FEATURE. BOTH THE NAM12 AND HRRR RUC SUGGEST A MESO-LOW FEATURE
WILL DEVELOP ON THE EAST SIDE (MICHIGAN SIDE)OF THE LAKE AN TRACK
SOUTH THROUGH THE NIGHT ENHANCING THE CONVERGENCE OVER THE LAKE.
GIVEN THE 850 MB TO LAKE TEMP DIFFERENCE IS NEAR 15C. BUFKIT SHOWS
THE EQUILIBRIUM LEVEL OVERNIGHT WILL APPROACH 30000 FT AGL WITH
NEARLY 2000 J/KG OF LAKE INDUCED CAPE. I AM THINKING THIS IS
ENOUGH FOR SCT TO ISOLATED THUNDERSTORMS. LOCALLY HEAVY SHOWERS
SHOULD BE EXPECTED. THAT THINKING IS CONFIRMED BY THE SPC SREF.
NEARLY ALL OF THIS WILL MOSTLY BE OVER LAKE MICHIGAN AND WEST OF
US-131 WHERE THE LAKE INDUCED INSTABILITY WILL BE A FACTOR. INLAND
OF THAT EXPECT PARTLY CLOUDY SKIES WITH POSSIBLY A PASSING SHOWER
AS THE UPPER WAVE MOVE THROUGH.
ONCE THIS FEATURE EXITS THE AREA MID TO LATE MORNING SUNDAY THE
UPPER RIDGE BUILDS IN THROUGH TUESDAY. THERE WILL BE ENOUGH
INSTABILITY YET FOR ISOLATED SHOWERS SOUTH OF ROUTE 10 AND EAST OF
US-131 SUNDAY AFTERNOON SINCE THE UPPER JET WILL NOT BE EAST OF
THERE YET.
SUNDAY NIGHT WITH SURFACE HIGH PRESSURE OVER THE AREA WINDS WILL
BE LIGHT AND SKIES CLEAR. I EXPECT LOWS IN THE MID 30S OVER OUR NE
CWA AND LOWER TO MID 40S ELSEWHERE. A SLOW WARMING TREND FOLLOWS
THEN WITH MOSTLY CLEAR SKIES THROUGH TUESDAY NIGHT.
.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 305 PM EDT SAT SEP 8 2012
WE/LL START TO WARM UP AGAIN TUESDAY AS THE HIGH MOVES TOWARD NEW
ENGLAND. THE NEXT COLD FRONT WILL LIKELY MOVE ACROSS THE CWA
THURSDAY NIGHT OR FRIDAY. INSTABILITY DOESN/T LOOK VERY IMPRESSIVE
WITH THIS NOR DO THE MOISTURE TRANSPORT VECTORS. AS A RESULT I
CAN/T SEE MUCH MORE THAN SLIGHT CHC POPS AT THIS POINT. THERE IS A
COMPACT SHORT WAVE ASSOCIATED WITH THIS AND THAT MAY BOOST PCPN
CHANCES INTO SATURDAY...BUT GIVEN THE SFC RIDGING MOVING IN AT
THAT POINT...PCPN AMOUNTS AND CHANCES LOOK MEAGER.
TEMPS WILL CLIMB TO AROUND 80 PRIOR TO FROPA AND THAN BACK INTO THE
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 757 PM EDT SAT SEP 8 2012
EXTRAPOLATION TOOLS INDICATE THAT THE INITIAL BAND OF LIGHT
SHOWERS IN WI SHOULD ARRIVE IN MKG AROUND 02Z. HOWEVER THE MAIN
IMPACT SHOULD COME WITH THE SECOND LINE OF CONVECTION IN WI...
WHICH ARRIVES IN MKG AROUND 03Z. WOULD EXPECT THERE TO BE SOME
ISOLATED TSTMS AND GUSTY WINDS AS THE POTENT TROUGH AND ASSOCIATED
COLD AIR ALOFT INTERACTS WITH THE VERY WARM LAKE WATERS LATER
TONIGHT.
COVERAGE OF SHOWERS/TSTMS LATER THIS EVENING IS EXPECTED TO BE
MUCH LESS INLAND FROM LAKE MICHIGAN... SO DID NOT INCLUDE ANY
MENTION OF TSTMS/GUSTY WINDS IN THE OTHER TAFS... JUST MKG.
OUTSIDE OF SHOWER ACTIVTY... VFR CIGS/VSBYS WILL PREVAIL TONIGHT
AND SUNDAY.
&&
.MARINE...
ISSUED AT 633 PM EDT SAT SEP 8 2012
ISSUED ANOTHER SCA FOR THE NRN ZONE. GUSTY WINDS EXPECTED WITH THE
NEXT COLD FRONT CURRENTLY MOVING ACROSS WISCONSIN.
&&
.HYDROLOGY...
ISSUED AT 252 PM EDT SAT SEP 8 2012
RIVERS WILL CONTINUE TO FALL SLOWLY THROUGH THIS COMING WEEK AS
IT IS EXPECTED TO BE DRY MOST OF THIS COMING WEEK. ANY RAINFALL
WE GET TONIGHT WILL ONLY BE NEAR THE LAKE SHORE AND THAT WILL NOT
IMPACT MOST OF RIVERS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR LMZ847>849.
SMALL CRAFT ADVISORY UNTIL 6 PM EDT SUNDAY FOR LMZ844>846.
&&
$$
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...93
AVIATION...MEADE
HYDROLOGY...WDM
MARINE...93
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
733 PM EDT SAT SEP 8 2012
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 426 PM EDT SAT SEP 8 2012
MAIN FOCUS OF THE SHORT TERM IS THE STRONG SHORTWAVE SLIDING SSE
THROUGH NE MN AND WRN LK SUPERIOR AND THE ASSOCIATED SFC COLD FRONT.
AHEAD OF THIS SHORTWAVE...AREA OF SHOWERS HAS DROPPED OUT OF CANADA
THIS MORNING AND INTO FAR WRN UPPER MI. EXPECT THESE SHOWERS TO
CONTINUE TO SLIDE TO THE SE OVER THE COUNTIES NEAR THE WI BORDER
THROUGH THE REST OF THIS AFTN...ASSOCIATED WITH THE H850-500
Q-VECTOR CONV. BEHIND THIS INITIAL AREAS OF SHOWERS AND THE
FRONT...SCATTERED SHOWERS HAVE DEVELOPED UNDER THE CENTER OF THE
SHORTWAVE AND ASSOCIATED WITH AREA OF STEEP MID LVL LAPSE RATES.
THESE SHOWERS SHOULD CONTINUE TO THE SSE AND LARGELY MISS THE
CWA...BUT COULD SEE SOME SCATTERED SHOWERS OVER THE WEST UNTIL
DIURNAL HEATING IS LOST AND THE SHORTWAVE SLIDES S OF THE CWA.
ATTENTION THEN TURNS TO POTENTIAL LK ENHANCED SHOWERS AND CLOUDS FOR
TONIGHT. RUC ANALYSIS IS SHOWING THAT H850 TEMPS HAVE WARMED A
DEGREE OR TWO FROM THIS MORNING...TOWARDS 6-7C OVER THE WEST AHEAD
OF THE SHORTWAVE. ONCE THIS WAVE AND THE SFC FRONT SLIDE SE OF THE
AREA...EXPECT H850 TEMPS TO FALL TOWARDS 5C BY THIS EVENING AND THEN
4C BY 12Z SUN. WITH LK SUPERIOR TEMPS IN THE 17-21C RANGE...THIS
SHOULD PROVIDE DECENT DELTA-T VALUES FOR LK ENHANCED SHOWERS/CLOUDS.
THE MAIN QUESTION FOR TONIGHT INTO SUN MORNING IS THE AMNT OF
MOISTURE AND IT/S LOCATION. WITH THE TRACK OF THE SHORTWAVE AND
MOISTURE UPSTREAM INTO ONTARIO...EXPECT FAR WRN UPPER MI TO SEE THE
BEST OPPORTUNITY FOR LK ENHANCED SHOWERS UNDER THE NRLY BL FLOW.
THAT AREA WILL BE AIDED BY COASTAL CONVERGENCE AND UPSLOPE FLOW...SO
HAVE HIGH END CHANCE POPS THROUGH MUCH OF THE NIGHT. WITH A SLIGHT
DELAY TO THE COLDEST TEMPS...MAY SEE A SHORT BREAK IN THE SHOWERS
AFTER THE SUN GOES DOWN AND BEFORE THE COLD AIR ARRIVES. FARTHER NE
IS A LITTLE MORE UNCERTAIN. MODELS SHOWING H850-700 DRY AIR DROPPING
S FROM CNTRL ONTARIO AND OVER CNTRL/ERN LK SUPERIOR THIS EVENING AND
OVER CNTRL/ERN UPPER MI OVERNIGHT. WITH THE LACK OF CU THAT HAS
DEVELOPED NE OF THUNDER BAY...THAT SEEMS FAIRLY REASONABLE.
BUT...H925-850 MOISTURE AND STEEP LAPSE RATES OVER LK SUPERIOR WITH
THE NRLY FLOW SHOULD STILL PRODUCE ISOLATED TO POTENTIALLY SCATTERED
LK ENHANCED SHOWERS OVER THE NCNTRL CWA WITH THE LIMITED CLOUD DEPTH
KEEPING THEM LIGHT. ALL OF THESE SHOWERS MAY BE HELPED BY A
SECONDARY SHORTWAVE FROM NW ONTARIO MOVING THROUGH OVERNIGHT.
FOR TOMORROW...WITH LINGERING LLVL MOISTURE AND 3-4C H850
TEMPS...THE NNW WIND FAVORED LOCATIONS SHOULD SEE PARTLY/MOSTLY
CLOUDY SKIES THROUGH THE MORNING HOURS. STILL LINGERED LIGHT SHOWERS
THROUGH THE MORNING...BUT LIMITED MOISTURE DEPTH SUPPORTS ONLY
HAVING SLIGHT CHANCES. OVER THE CNTRL/EAST IN THE AFTN...MOISTURE
THAT IS CURRENTLY OVER NW ONTARIO SHOULD DROP OVER THE ERN LK AND
WITH THE COLD TEMPS REINFORCE THE CLOUD DECK. NCEP WRF NMM/ARW RUNS
HAVE SHOWN THE POTENTIAL FOR SHOWERS WITH THIS WAVE...BUT CONCERNED
DRIER AIR ALOFT WILL KEEP CLOUDS FROM DEVELOPING TOO MUCH. FARTHER
WEST...HIGH PRESSURE BUILDING IN UNDER THE UPPER RIDGING WILL HELP
BRING DRIER AIR INTO THE AREA AND DECREASE THE CLOUDS DURING THE
AFTN AND LEAD TO CLEARING AFTER 21Z.
FINALLY...WITH THE NORTHERLY WINDS CREATING 3-5FT WAVES
TOMORROW...EXPECT A MODERATE TO HIGH RISK OF RIP CURRENTS TO
CONTINUE TOMORROW.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 426 PM EDT SAT SEP 8 2012
MEDIUM RANGE GUIDANCE CONTINUES TO BE IN GENERAL AGREEMENT ON THE
BIG PICTURE OVER THE NEXT 7 DAYS AS IT PERTAINS TO UPPER MI. AFTER
THIS WEEKENDS TROF...PATTERN WILL BECOME MORE PROGRESSIVE NEXT WEEK.
THE TROF DOMINATING THE GREAT LAKES THIS WEEKEND WILL BE FOLLOWED BY
RIDGING EARLY IN THE WEEK...A TROF FOR THE MID/LATE PORTION OF THE
WEEK...AND ANOTHER TROF LATE NEXT WEEKEND. THE EVOLUTION/STRUCTURE
OF THE MID/LATE WEEK TROF REMAINS THE MAIN AREA OF MODEL
DISAGREEMENT. WITH A PROGRESSIVE PATTERN...TEMPS WILL SHOW A FAIR
AMOUNT OF VARIATION OVER THE NEXT 7 DAYS. TEMPS A LITTLE BLO NORMAL
THRU THE WEEKEND WITH TROFFING OVER THE GREAT LAKES WILL TRANSITION
TO STRONG WARMING/ABOVE NORMAL TEMPS EARLY IN THE WEEK AHEAD OF THE
NEXT APPROACHING TROF. GRADUAL COOLING WILL OCCUR MIDWEEK...LEADING
TO TEMPS AROUND NORMAL LATE IN THE WORK WEEK AS MID/UPPER LEVEL
TROF PASSES. TEMPS WILL THEN BEGIN TO REBOUND FOR THE START OF NEXT
WEEKEND. AS FOR PCPN...THIS WILL BE AN OVERALL DRY PERIOD DUE TO
LACK OF GULF MOISTURE TRANSPORT TO THE UPPER LAKES AND DUE TO MAIN
FORCING PASSING N OF THE AREA WHEN SHORTWAVES PASS.
BEGINNING SUN NIGHT...WITH SFC HIGH PRES RIDGE PASSING ACROSS THE
AREA...CLR SKIES AND PRECIPITABLE WATER 45-65PCT OF NORMAL...A GOOD
RADIATIONAL COOLING NIGHT IS EXPECTED. MINS ON THE LOW SIDE OF AVBL
GUIDANCE LOOK ON TRACK. TRADITIONAL INTERIOR COLD SPOTS SHOULD DROP
TO THE UPPER...POSSIBLY MID...30S. MIGHT SEE A LITTLE FROST.
AS MID LEVEL RIDGE SHIFTS TO THE UPPER LAKES MON...WAA WILL BE
UNDERWAY. LOW-LEVEL JET/STRONGEST PUSH OF WARMING IS WELL TO THE NNW
MON...SO PCPN IS NOT A CONCERN. TEMPS SHOULD REBOUND INTO THE 70S
UNDER WAA PATTERN.
AS THE MID LEVEL RIDGE SHIFTS E TUE AND NEXT TROF BEGINS TO MOVE OUT
OVER THE NRN PLAINS...850MB THERMAL RIDGE (TEMPS OF 16-19C) WILL
TRANSLATE OVER THE AREA. ALTHOUGH THERE REMAINS SOME CONCERN WITH
MID/HIGH CLOUD COVERAGE TUE...THERMAL RIDGE AND BREEZY S-SW WINDS
WILL LEAD TO A WARM DAY FOR EARLY/MID SEPT...ESPECIALLY OVER THE W
HALF. WILL STAY WITH HIGH TEMPS MAINLY LOW/MID 80S...ABOVE ALL
GUIDANCE IN MOST AREAS. NOT TOTALLY OUT OF THE QUESTION THAT SOME OF
THE DOWNSLOPE AREAS OVER THE W TOWARD LAKE SUPERIOR COULD FLIRT WITH
90F IF THE DAY ENDS UP SUNNY. COOLER READINGS WILL BE OVER THE E
WITH FLOW UP LAKE MICHIGAN. WITH LOW-LEVEL JET TRANSLATING ACROSS
THE AREA...THERE IS A VERY SMALL POTENTIAL FOR SOME CONVECTION...BUT
LACK OF BETTER MOISTURE MINIMIZES THE POTENTIAL.
MEDIUM RANGE GUIDANCE HAS CONTINUED TO SLOW DOWN SLIGHTLY THE COLD
FRONT ASSOCIATED WITH THE INCOMING MID LEVEL TROF MIDWEEK. IT NOW
APPEARS FRONT WILL BE CROSSING THE AREA DURING THE DAY WED. WITH
BEST DEEP LAYER FORCING PASSING WELL TO THE N AND WITH A LACK OF A
GOOD GULF MOISTURE CONNECTION...THERE SHOULDN`T BE MUCH PCPN
ASSOCIATED WITH THE FRONT. HOWEVER...WITH THE UPPER TROF TAKING ON A
POSITIVE TILT FROM HUDSON BAY TO THE NRN PLAINS THRU THU...THE
SUPPORTING SW-NE ORIENTED UPPER JET WILL SLOWLY TRANSLATE EASTWARD.
AS IT DOES...RIGHT ENTRANCE UPPER DIVERGENCE WILL BEGIN TO OVERLAY
THE LOW-LEVEL FRONT...LIKELY LEADING TO A RIBBON SHRA EVENTUALLY
DEVELOPING ALONG/BEHIND SFC FRONT AS SUGGESTED BY THE
GFS/ECMWF/GLOBAL GEM. THUS...PLAN TO MAINTAIN SCHC POPS OVER THE FAR
W LATE TUE NIGHT INTO WED WITH SCHC POPS EXPANDING INTO THE CNTRL
WED AND THEN CHC POPS OVER THE E HALF WED NIGHT. INSTABILITY IS VERY
LIMITED...SO POTENTIAL OF THUNDER IS MINIMAL. LINGERED SCHC POPS
OVER ALL BUT THE FAR W THU GIVEN MODEL TRENDS...BUT MAY NEED TO
INCREASE THU POPS TO CHC IF CONSISTENCY DEVELOPS FOR SLOW FRONTAL
MOVEMENT AND AN INCREASED POST FRONTAL PCPN BAND WITH TIME DUE TO
UPPER JET.
SINCE YESTERDAY`S RUNS...GFS/ECMWF HAVE TRENDED COOLER FOR FRI AS
THE MID/UPPER LEVEL TROF PASSES (850MB TEMPS 3-5C TO START THE DAY).
AS A RESULT...TEMPS WILL BE BACK AROUND NORMAL MID SEPT VALUES (60S
FOR HIGHS). MIGHT BE SOME LAKE EFFECT -SHRA FRI MORNING IN THE
CHILLY NW FLOW. OTHERWISE...DRY WEATHER IS EXPECTED FRI. HOWEVER...
IT IS NOTED THAT THE 00Z GFS AND NOW THE 12Z ECMWF SHOW ENERGY IN
THE SRN PORTION OF PASSING TROF SEPARATING OUT AND LEADING TO A MID
LEVEL LOW TRACKING INTO THE UPPER LAKES FRI INTO EARLY SAT. GIVEN
THE VERY INCONSISTENT SIGNAL...WILL IGNORE THIS IDEA FOR NOW. WILL
BE SOMETHING TO KEEP IN MIND WHICH MAY CHANGE THE CURRENT DRY FCST
TO A POSSIBLE GOOD SOAKING. IN THE ABSENCE OF THE POSSIBLE MID LEVEL
LOW...DRY WEATHER/WARMING IS EXPECTED SAT AS WEAK MID LEVEL RIDGE
ARRIVES. NEXT SHORTWAVE TROF SHOULD ARRIVE SUN.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 732 PM EDT SAT SEP 8 2012
A STRONG SHORTWAVE TROUGH DROPPING SSE THROUGH UPPER MIN MN ALONG
WITH A SFC COLD FRONT WILL BRING SCT SHOWERS INTO WRN UPPER MI EARLY
THIS EVENING. BEHIND THE FRONT AND SHORTWAVE...EXPECT A TRANSITION
TO LK ENHANCED CLOUDS/RAIN TO OCCUR LATE THIS EVENING AND CONTINUE
INTO SUN MORNING. WITH THE BEST MOISTURE/FETCH AFFECTING
KIWD/KSAW...HAVE CONTINUED FCST OF MVFR CONDITIONS TONIGHT THROUGH THE
MORNING HOURS. DRIER AIR ALOFT LEADS TO MORE UNCERTAINTY ON THE
COVERAGE OF CLOUDS AND RAIN POTENTIAL AT KCMX...SO WILL KEEP VFR
CONDITIONS FOR NOW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 426 PM EDT SAT SEP 8 2012
A SFC TROUGH DROPPING SE ACROSS LAKE SUPERIOR THIS EVENING WILL
BRING A REINFORCING SHOT OF COLD AIR AND STRENGTHEN THE NNW WINDS
ACROSS LAKE SUPERIOR. THE HIGHEST GUSTS...TO 30KTS...WILL BE SEEN
OVER FAR WRN LK SUPERIOR...WILL THE REST OF THE LAKE WILL SEE
15-25KTS TONIGHT INTO TOMORROW. HIGH PRESSURE WILL BUILD OVER THE
UPPER GREAT LAKES TOMORROW AND LEAD TO WEAKENING WINDS SUN AFTN AND
SUNDAY NIGHT. AS THE HIGH QUICKLY SHIFTS TO THE LOWER GREAT LAKES
ON MONDAY...SOUTHERLY WINDS WILL INCREASE AND PRODUCE A PERSISTENT
PERIOD OF 15-25KT WINDS THROUGH TUESDAY NIGHT WHEN A COLD FRONT
PUSHES ACROSS LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...JLB
MARINE...SRF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
252 AM CDT FRI SEP 7 2012
.DISCUSSION...
THE LEADING EDGE OF A COOL CANADIAN AIR MASS WAS JUST SOUTH OF A
KFRM TO KEAU LINE EARLY THIS MORNING. AS EXPECTED...THE LLJ AND
ASSOCIATED MOISTURE ADVECTION WAS JUST SOUTH OF THE FA GENERATED
TSRA JUST SOUTH OF THE IOWA BORDER. THE OTHER FORCING ACROSS
CENTRAL MN/NORTHERN WI WHICH WAS ASSOCIATED WITH A STRONG JET
STREAK OF 120-130 KTS MOVING ACROSS SD EARLY THIS MORNING.
THE ACTIVITY IN CENTRAL MN/N WI HAS BEEN RELATIVELY LIGHT IN
RESPECT TO QPF AMTS...BUT COVERAGE HAS BEEN FAIRLY CONSISTENT FROM
NEAR KBRD TO SOUTH OF KDLH. ALTHOUGH THE JET STREAK WILL CONTINUE
TO ENHANCE PRECIPITATION ACROSS N WI/WC MN THRU SUNRISE...HOW FAR
SOUTH THIS BAND EXPANDS REMAINS IN QUESTION.
ANOTHER VIGOROUS SHRTWV JUST SOUTH OF WINNIPEG IS PROGGED TO MOVE
S/SE ACROSS MN OVER THE NEXT 6 TO 12 HRS. THIS AREA OF ENHANCED
LIFT SHOULD CONTINUE AT LEAST A SMALL CHC OF SHRA ACROSS FAR S
MN/WC WI. IN ADDITION...ANOTHER JET STREAK ACROSS WESTERN NEBRASKA
MAY CONTRIBUTE TO ADDITIONAL LIFT ACROSS FAR S MN AFT 12Z. SIMILAR
SCENARIOS WITH -SHRA EXPANDING ACROSS FAR S MN AFT 12Z IS DEPICTED
IN THE LATEST WRF REFLECTIVITY MODEL ALONG WITH MPX LOCAL MODEL
DEPICTION OF THE REFLECTIVITY PATTERN. ONCE THE MEAN UPPER WAVE
MOVES ACROSS MN...EXPECT THE PRECIPITATION TO END...WITH SOME
ISOLD -SHRA ACROSS THE FAR EASTERN FA DUE TO RESIDUAL MOISTURE AND
AMPLE COLD AIR ALOFT TO GENERATE INSTABILITY SHRA IF SOME BREAKS IN
THE OVERCAST DEVELOP.
ONE MINOR CHG IN THE UPCOMING WEEKEND FORECAST IS BASED ON ANOTHER
SHRTWV MOVING SE ACROSS THE WESTERN GREAT LAKES SATURDAY
AFTN/EVENING. ALTHOUGH DEEP MOISTURE WILL BE LIMITED...STRONG
ISENTROPIC LIFT ASSOCIATED WITH THE DIVING SHRTWV SHOULD AT LEAST
GENERATE A FEW SHRA OVER PORTIONS OF WC WI. EVEN SOME LAKE EFFECT
SHRA MAY CLIP SOME OF OUR EASTERN FA DUE TO THE STRENGTH OF THIS
SHRTWV. TEMPS WILL BE TRICKY FOR SATURDAY MORNING...AND AGAIN
SUNDAY MORNING DUE TO WIND SPDS INCREASING AHEAD OF SATURDAY
SYSTEM. EXPECT THAT SATURDAY MAY NOT BE THE COLDEST MORNING WITH
SOME MIXING IN THE LOW LEVELS. SUNDAY MORNING LOOKS TO BE THE
COOLEST AS THE RIDGE BUILDS OVERHEAD. ALTHOUGH AM NOT EXPECTING
ANY WIDESPREAD FROST SUNDAY MORNING...THERE WILL BE THE TYPICAL
LOW LYING AREAS IN CENTRAL MN...AND WC WI WHERE THE MERCURY WILL
DIP INTO THE MID 30S. LATER FORECASTS CAN START TO INTRODUCE
PATCHY FROST IF THIS SCENARIO DEVELOPS. AFT SUNDAY...A STRONG
RETURN FLOW WILL COMMENCE WITH FIRE WX CONCERNS MONDAY AFTN DUE TO
THE STRENGTH OF THE SFC WINDS...AND RH FIELDS DROPPING INTO THE
CRITICAL RANGES. WILL HIGHLIGHT THE HWO WITH FIRE WX CONCERNS FOR
MON...AND POSSIBLY TUE IN THE SE FA. ..JLT..
&&
.AVIATION.../06Z TAF ISSUANCE/
SFC LOW TAKING SHAPE THIS EVENING NEAR OMAHA...WITH COLD FRONT AT
4Z STILL HUNG UP FROM NEAR RWF UP TOWARD CAMBRIDGE. THIS FRONT
WILL START MAKING PROGRESS SE AFTER 6Z AS THE LOW HEADS INTO
CENTRAL IA. HRRR HAS PICKED UP ON CURRENT CONDITIONS WELL...AND IN
GENERAL FOLLOWED IT FOR SHRA TIMING IN TAFS...WHICH RESULTED IN
PUSHING -SHRA MENTION BACK A COUPLE OF HOURS IN MOST CASES. STILL
EXPECT TWO PRIMARY AREAS OF PRECIP TONIGHT...A BAND OF RAIN MAINLY
NORTH OF I-94 WITH THUNDERSTORMS ACROSS IA. CONFIDENCE DECREASING
IN SEEING MVFR CIGS OVERNIGHT...AS MODELS SHOWING THERE SHOULD
ALREADY BE SUCH CIGS OVER CENTRAL MN...BUT ALL CIGS ARE STILL OVER
050. LEFT A BRIEF MENTION FOR MVFR CIGS ONLY AT WI TERMINALS...
WHERE HEAVIEST PRECIP LOOKS TO FALL. FOR TOMORROW...STRONG COLD
AIR ADVECTION WILL SUPPORT BKN-OVC CIGS BETWEEN 040 AND 060
THROUGH MUCH OF THE AFTERNOON.
FOR WINDS...E-NE WINDS WILL QUICKLY SWING AROUND TO THE NW THIS
TONIGHT AS THE SFC LOW WORKS ACROSS IA. NW SPEEDS WILL QUICKLY
PICK UP IN THE MORNING...WITH GUSTS INTO THE 20S STILL LOOKING
GOOD.
KMSP...WILL CONTINUE TO SEE BOUTS OF VFR SHOWERS THROUGH ABOUT
10Z. WITH LACK OF MVFR CIGS ACROSS CENTRAL MN...AND VERY DRY LOW
LEVELS IN 00Z KMPX SOUNDING...REMOVED MVFR CIG MENTION...THOUGH AN
020 TO 030 CIG CAN NOT BE RULED OUT MAINLY BETWEEN 10Z AND 13Z.
/OUTLOOK FOR KMSP/
SATURDAY THROUGH TUESDAY...VFR CONDITIONS EXPECTED.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
JLT/MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1105 PM CDT THU SEP 6 2012
.UPDATE...
06Z AVIATION DISCUSSION ADDED BELOW.
&&
.DISCUSSION...
/ISSUED 332 PM CDT THU SEP 6 2012/
AT 3 PM...A COLD FRONT WAS ANALYZED ROUGHLY FROM KHYR...TO
KAXN...AND KHON. TEMPERATURES NORTH HAVE FALLEN INTO THE 50S AND
60S WITH 70S AND 80S COMMON SOUTH. THIS FRONT WILL CONTINUE TO
TREK SOUTH THIS EVENING AND CLEAR THE FORECAST AREA BY MIDNIGHT.
TONIGHT...POSITIVELY TILTED UPPER LEVEL WAVE WILL TRAVERSE THE
REGION OVER THE NEXT 24 HOURS. AS IT DOES SO...UPPER LEVEL FORCING
ASSOCIATED WITH THE POSITIVE VORTICITY ADVECTION WILL RESULT IN
LOW/MID LEVEL CONVERGENCE AS ALREADY SEEN IN THE H850 SPC
MESOANALYSIS. THIS NORTH/SOUTH CONVERGENCE ALONG THE LATITUDINALLY
ORIENTED ISENTROPES WILL INDUCE AN AREA OF FRONTOGENESIS ACROSS
CENTRAL MN AND NORTHERN WI. PRECIPITATION IS EXPECTED TO INCREASE
IN COVERAGE THIS EVENING...WITH THE HEAVIEST BAND SETTING UP NORTH
OF I-94. HAVE LEFT ISOLATED THUNDER MENTION IN THE GRIDS GIVEN THE
STRONG SYNOPTIC FORCING AND THIN AREA OF CAPE AS SEEN IN THE
FORECAST SOUNDINGS. AS OF THIS AFTERNOON...ALREADY HAD A FEW
THUNDERSTORMS DEVELOPING ACROSS THE WESTERN CWA. FURTHER TO THE
SOUTH THE LOW LEVEL JET WILL INCREASE OVERNIGHT WITH ELEVATED
THUNDERSTORMS EXPECTED ACROSS IOWA LATE THIS EVENING. THE BEST
MOISTURE CONVERGENCE AS SEEN IN THE H925 FIELDS IS SOUTH OF THE
IA/MN BORDER...BUT HAVE A SECOND AREA OF CONCENTRATED POPS ACROSS
THE SOUTH TONIGHT.
PRECIPITATION WILL RAPIDLY END FRIDAY MORNING AS DRIER MID LEVEL
AIR PROPAGATES SOUTHWARD. STEEP LOW LEVEL LAPSE RATES IN STRONG
CAA ENVIRONMENT WILL MAINTAIN STRATOCU FIELD INTO LATE AFTERNOON.
REMOVED SCHC POPS OVER WCTRL WI DURING THE AFTERNOON WITH A VERY
SHALLOW CLOUD DEPTH. GUSTY WINDS EXPECTED WITH FORECAST SOUNDINGS
INDICATING A FEW GUSTS OF 25 TO 30 MPH POSSIBLE. MIXING 925 MB
TEMPS DOWN TO THE SURFACE INDICATE TEMPERATURES MAXING OUT ONLY IN
THE MID 60S.
CLEAR AND COLD NIGHT EXPECTED FRIDAY NIGHT. HIGH PRESSURE SLIDING
WELL SOUTH INTO THE CENTRAL PLAINS SHOULD KEEP WINDS SOMEWHAT
MIXED THROUGH THE NIGHT IN MOST LOCATIONS...PREVENTING
TEMPERATURES FROM BOTTOMING OUT TOO MUCH. STILL COULD SEE A FEW
STATIONS FALL INTO THE UPPER 30S...BUT THE THREAT OF ANY FROST IS
NEGLIGIBLE.
A HIGHLY AMPLIFIED PATTERN WILL PLAY OUT FOR THE WEEKEND WITH THE
CWA STUCK BETWEEN THE TROUGH AND THE RIDGE. A WEAK UPPER
DISTURBANCE EMBEDDED IN THE STRONG NORTH FLOW MAY BRING A THREAT
FOR A SHOWER OVER WCTRL WI SATURDAY AFTERNOON. OTHERWISE...DRY
CONDITIONS ARE EXPECTED.
THE WHOLE PATTERN WILL SHIFT EAST EARLY NEXT WEEK WITH MUCH WARMER
TEMPERATURES RETURNING. THICKNESSES WILL RISE FROM AROUND 560 DAM
SATURDAY AFTERNOON TO 576+ DAM BY TUESDAY. SHOULD SEE HIGHS
APPROACHING 90 IN SWRN MN MONDAY...AND UPPER 80S AT LEAST ACROSS
WCTRL WI/SERN MN TUESDAY AS THE THERMAL RIDGE SETTLES OVERHEAD.
THESE HIGHS ARE SEVERAL DEGREES ABOVE GUIDANCE VALUES WHICH SEEM
TOO COOL IN SUCH A PATTERN.
THE NEXT FRONT WILL ARRIVE TUESDAY AFTERNOON/NIGHT BUT SHOULD
SWING THROUGH MOSTLY DRY. MAINTAINED SCHC POPS WITH IT.
A MILD/WARM ZONAL FLOW RETURNS FOR THE MIDDLE OF NEXT WEEK WITH NO
REAL COLD AIR INTRUSIONS IN SIGHT.
&&
.AVIATION.../06Z TAF ISSUANCE/
SFC LOW TAKING SHAPE THIS EVENING NEAR OMAHA...WITH COLD FRONT AT
4Z STILL HUNG UP FROM NEAR RWF UP TOWARD CAMBRIDGE. THIS FRONT
WILL START MAKING PROGRESS SE AFTER 6Z AS THE LOW HEADS INTO
CENTRAL IA. HRRR HAS PICKED UP ON CURRENT CONDITIONS WELL...AND IN
GENERAL FOLLOWED IT FOR SHRA TIMING IN TAFS...WHICH RESULTED IN
PUSHING -SHRA MENTION BACK A COUPLE OF HOURS IN MOST CASES. STILL
EXPECT TWO PRIMARY AREAS OF PRECIP TONIGHT...A BAND OF RAIN MAINLY
NORTH OF I-94 WITH THUNDERSTORMS ACROSS IA. CONFIDENCE DECREASING
IN SEEING MVFR CIGS OVERNIGHT...AS MODELS SHOWING THERE SHOULD
ALREADY BE SUCH CIGS OVER CENTRAL MN...BUT ALL CIGS ARE STILL OVER
050. LEFT A BRIEF MENTION FOR MVFR CIGS ONLY AT WI TERMINALS...
WHERE HEAVIEST PRECIP LOOKS TO FALL. FOR TOMORROW...STRONG COLD
AIR ADVECTION WILL SUPPORT BKN-OVC CIGS BETWEEN 040 AND 060
THROUGH MUCH OF THE AFTERNOON.
FOR WINDS...E-NE WINDS WILL QUICKLY SWING AROUND TO THE NW THIS
TONIGHT AS THE SFC LOW WORKS ACROSS IA. NW SPEEDS WILL QUICKLY
PICK UP IN THE MORNING...WITH GUSTS INTO THE 20S STILL LOOKING
GOOD.
KMSP...WILL CONTINUE TO SEE BOUTS OF VFR SHOWERS THROUGH ABOUT
10Z. WITH LACK OF MVFR CIGS ACROSS CENTRAL MN...AND VERY DRY LOW
LEVELS IN 00Z KMPX SOUNDING...REMOVED MVFR CIG MENTION...THOUGH AN
020 TO 030 CIG CAN NOT BE RULED OUT MAINLY BETWEEN 10Z AND 13Z.
/OUTLOOK FOR KMSP/
SATURDAY THROUGH TUESDAY...VFR CONDITIONS EXPECTED.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1211 AM CDT FRI SEP 7 2012
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
Overnight rain chances diminishing with a much better bet starting
Friday morning. The convection which formed along the dryline from
north central KS through the TX Panhandle has steadily weakened
after pulling away from the boundary while the low level jet has
refocused west of ICT and is enhancing the activity headed for south
central KS. Latest HRRR finally caught on while 00Z NAM continues to
be basically dry overnight. Cold front is now over central NE and
dropping southeast. Will cut back on pops with chance wording held
back until after 09z. Eastern counties looking dry overnight. Much
stronger forcing aloft arrives Friday mid/late morning as a
shortwave deepens as it drops southeast through NE. High PoPs for
Friday morning/afternoon with rain threat quickly ending from nw-se.
MJ
&&
.PREV DISCUSSION...
/340 PM CDT Thu Sep 6 2012/
Short term concerns remain focused on precipitation potential
overnight and into Friday. Early this afternoon, shortwave energy
interacting with a well-defined corridor of 850:700 mb moisture and
prevailing westerly 700:500 mb flow produced a large complex of
thunderstorms in areas just south of the CWA boundary. Subsidence
behind this shortwave has allowed temperatures to jump back into the
lower 90s in the southern CWA and should stabilize the southeastern
zones into this evening.
Further northwest, eyes begin to turn towards an autumn-like cold
front stretching from north to south from central South Dakota
through central Nebraska and northwestern Kansas. A strong EML
continues to advect into area along and ahead of this surface
boundary, with 700 mb temperatures of 11-12C common into eastern
Nebraska. That said, a small CU field has developed over north
central Kansas this afternoon, which could be enhanced by a weak
shortwave exiting eastern Colorado. Should this activity develop, it
would track into south central Kansas this evening. While 19Z
aircraft sounding indicated 700mb temps of only 9-10C, latest
RAP/HRRR continue to advect warmer air aloft into the CWA which
should prevent an extensive eastward track of activity. The primary
focus for thunderstorms this evening appears to be turning towards
northeastern Nebraska, northwestern Iowa and southeast South Dakota,
where strong moisture transport has been pointed through the daytime
hours. Initial thoughts are that convection will begin to break out
early this evening along a weak surface low near Sioux Falls as
cooling aloft and lift on the nose of a 35 knot LLJ allows convection
to overcome a weaker cap.
With low level winds remaining focused well away from the CWA this
evening, have significantly trimmed back PoPs through 06z. Beyond
06z, some questions continue to linger as to whether weak lift will
be able to overcome a stronger cap over southern Nebraska. Latest
guidance continues to propagate an MCS into portions of central Iowa
and northern Illinois after midnight with much of the area remaining
dry through nearly 09z. Will still begin to increase PoPs after
midnight as lingering moisture axis will begin to interact more
directly with veering LLJ which could produce scattered
thunderstorms. Higher instability does begin to advect northeast
after midnight, creating some potential for an elevated hail threat.
While boundary layer will stabilize to some degree, surface winds
should remain fairly mixy, which could also promote a localized
damaging wind threat given LLJ running nearly parallel to the
surface boundary. A better chance for thunderstorm development
looks to begin after the 09Z timeframe when 850mb trough begins to
surge southeast and frontogenesis intensifies.
By 12Z the surface front should have already reached the St. Joseph
area, with precipitation rapidly beginning to increase. Strong
pressure rises behind the front will push the boundary through the
CWA by the noon hour, with period of showers and embedded thunder
through early afternoon. Will bump up PoPs further. While PWAT
values will be higher than normal, the rapid storm movement should
limit the heavy rainfall threat.
Precipitation will rapidly come to an end Friday afternoon, with the
surface high plunging southward. Beyond Friday night, the only
concerns will be with temperatures as high pressure dominates the
weekend. Readings on Saturday will be nearly perfect, with 70s
expected and a light northerly wind. Have lowered overnight lows
heading into Sunday as winds turn light and variable. Wouldn`t be
shocked to see 40 degree readings fairly widespread.
Dux
Sunday - Wednesday:
The region will still be under the influence of a modified Canadian
high pressure area Sunday resulting in quiet and seasonally cool
conditions. That high will gradually shift east of the region late
Sunday and into Monday with winds becoming southerly by Monday.
Temperatures should still be cooler than normal Monday but a rebound
is expected by Tuesday and Wednesday as thickness values increase
and temperatures aloft warm. The high will have swept moisture into
the central Gulf of Mexico, so despite warmer temperatures, moisture
will be limited and the chances for precipitation will be very small
through Tuesday night or Wednesday morning. By Wednesday afternoon,
another wave will track across the Northern Plains with its
associated cold front moving into Missouri Wednesday evening or
night. This will bring us our next chance for showers and storms,
though chances don`t look especially good at this point.
CDB
&&
.AVIATION...
For the 06Z TAFs: Rain chances have diminished considerably through
12z as upstream convection over KS fell apart as earlier thought.
Will need to await the arrival of the cold front which will track
southeast and move through the terminals between 12-16Z. While
isolated convection is possible in the pre-frontal zone will need to
await the arrival of much better upper support as a sharpening
shortwave swings through NE. Frontogenetical forcing aloft will also
play a role in generating widespread convection by late morning and
lasting through mid afternoon. How much thunder will accompany the
showers is debatable but still believe it best to keep it in a TEMPO
group vs prevailing. Some potential for MVFR ceilings with the
heavier showers as the rain band fills in by the noon hour.
Gusty north winds will gradually subside by late afternoon with
rapidly clearing skies by sunset.
MJ
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS GLASGOW MT
849 PM MDT SAT SEP 8 2012
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY...
EVENING UPDATE...
TWEAKS FOR THE EVENING INCLUDING SOME SLIGHT CHANGES TO CAPTURE
INVERSIONARY EFFECTS OF SURFACE TEMPERATURES DUE TO TERRAIN AND
COLD AIR DRAINAGE BEHIND THE STATIONARY FRONT. MESOSCALE MODELS
SUCH AS THE HRRR AND NAM5 AND ARW ALSO HELPED OUT IN DETAILING THE
OVERNIGHT WIND FIELD THROUGH NOON. GAH
PREVIOUS SHORT TERM DISCUSSION...
TONIGHT AND SUNDAY...THE UPPER LEVEL RIDGE AXIS MOVES EAST ACROSS
EASTERN MONTANA TONIGHT BUT HEIGHTS GET KNOCKED DOWN SLIGHTLY
FROM A WEAK EMBEDDED SHORTWAVE. BEHIND THIS SHORTWAVE A WARM FRONT
PUSHES NORTHEAST INTO NORTHEAST MONTANA WHICH WILL BRING IN A
SLIGHTLY WARMER NIGHT FROM LAST NIGHT. A LEE-SIDE SURFACE TROUGH
SWINGING EAST WILL SHIFT SOUTHEAST WINDS TO THE SOUTHWEST ON
SUNDAY. WARMER AIR BEHIND THE WARM FRONT WILL BUMP TEMPERATURES
HIGHER FOR SUNDAY. TEMPERATURES WILL RISE TO WELL ABOVE AVERAGE...
AROUND 10F TO 15F HIGHER THAN TODAY. THIS WILL LOWER RELATIVE
HUMIDITY TO LESS THAN 20 PERCENT. THE SURFACE TROUGH WILL TIGHTEN
THE PRESSURE GRADIENT ENOUGH TO MAKE WINDS BREEZY...MAINLY OVER
NORTH DAKOTA. HOWEVER WIND ALONG THE BORDER WILL BE OF CONCERN FOR
FIRE WEATHER. SEE FIRE WX DISCUSSION.
SUNDAY NIGHT/MONDAY...AN UPPER DISTURBANCE...OUT IN FRONT OF THE
UPPER TROUGH SWINGING INTO THE PAC-NW...WILL SEND A WEAK COLD
FRONT OVER THE AREA . THIS WILL CAUSE A WIND SHIFT TO THE WEST
MONDAY MORNING. WINDS BECOME STRONG OVER SOUTHERN SASKATCHEWAN AND
IN THE ZONES NEXT TO THE INTERNATIONAL BORDER. WITH WARMER THAN
NORMAL OVERNIGHT TEMPERATURES...RH RECOVERY COULD BE POOR. SO
EXPECT MINIMUM RH VALUES ON MONDAY TO GET DOWN BELOW 20 PERCENT
AGAIN. WITH STRONG WINDS...FIRE CONCERNS CONTINUE. SCT
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
NO SIGNIFICANT CHANGES TO THE EXTENDED PERIOD AS MODELS REMAIN IN
GOOD AGREEMENT AND ON TRACK. COLD FRONT EXPECTED THROUGH THE
REGION ON MONDAY NIGHT WITH COLD AIR LINGERING THROUGH THURSDAY.
SLIGHT RIDGING THEN OCCURS WITH ANOTHER COLD FRONT INDICATED FOR
FRIDAY NIGHT. EBERT
PREVIOUS LONG TERM DISCUSSION...THE EXTENDED FORECAST BEGINS WITH
A COLD FRONT MOVING THROUGH NORTHEAST MONTANA WITH STRONG COLD AIR
ADVECTION...AND LITTLE PRECIPITATION. THE GFS AND EC ARE IN GOOD
AGREEMENT WITH THE TIMING OF THE COLD AIR.
TUESDAY THROUGH THURSDAY NIGHT EXPECT COOL FALL LIKE CONDITIONS
ACROSS THE REGION UNDER NORTHWEST FLOW. TEMPERATURES WILL BE
AROUND THE SEASONAL NORMALS. STILL NO RAINFALL EXPECTED.
RIDGING BUILDS IN FOR NEXT WEEKEND FOR ABOVE NORMAL TEMPERATURES
AGAIN... STILL NO PRECIPITATION EXPECTED.
AFTER SEVERAL DAYS THE MODELS REMAIN IN FAIR AGREEMENT THROUGH THE
EXTENDED FOR GOOD CONFIDENCE IN THE FORECAST. PROTON
&&
.AVIATION...
VFR. CLEAR SKIES...WITH LIGHT WINDS BECOMING SOUTHEAST OVERNIGHT.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON
FOR MTZ120-122-134>137.
RED FLAG WARNING FROM NOON TO 9 PM MDT SUNDAY FOR MTZ120-122.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
637 AM CDT FRI SEP 7 2012
.UPDATE...
.AVIATION...
VFR IS EXPECTED MOST AREAS TODAY AND TONIGHT.
LIGHT RAIN AND LOCALLY MVFR CIGS OVC025 MAY BE DEVELOPING BENEATH
SOME OF THE STRONGER RADAR RETURNS. GIVEN THE COUPLED JET
STRUCTURE FOCUSED ALONG AND NORTH OF NEBRASKA HIGHWAY 2...THE RAPID
UPDATE MODELS...HRRR AND RAP MAINTAIN THIS FEATURE ACROSS NRN NEB
THIS MORNING AND PERHAPS UNTIL 21Z. THEREAFTER THE DISTURBANCE
SHOULD MOVE EAST WITH VFR BECOMING ABSOLUTE THROUGH 12Z SATURDAY
MORNING. OTHERWISE THE PREDOMINATE CIGS SHOULD OPERATE AS OVC070.
&&
.PREV DISCUSSION... /ISSUED 352 AM CDT FRI SEP 7 2012/
DISCUSSION...
PRIMARY FORECAST ISSUES TODAY INCLUDE TEMPERATURES TODAY AND
TONIGHT AS WELL AS THE LIGHT RAIN FOR TODAY. THEN GOING ON THROUGH
THE NEXT WEEK...WARMING CONDITIONS AND BREEZY WINDS RETURN WHICH
AGAIN BRINGS FIRE CONCERNS BACK TO THE FOREFRONT. THEN INTO THE
MIDDLE PART OF NEXT WEEK...FORECAST ISSUES INVOLVE A DECENT
COOLING TREND AND CHANCES FOR RAIN.
AT 07.07Z WATER VAPOR IMAGERY SHOWED A SHORTWAVE TROUGH EXTENDING
FROM THE UPPER LOW OVER SOUTHERN HUDSON BAY THROUGH NORTH DAKOTA
AND INTO MONTANA AND IDAHO. BROAD RIDGING REMAINED OVER THE DESERT
SOUTHWEST INTO TEXAS AND THE LOWER MISSISSIPPI RIVER
VALLEY...WHILE RIDGING WAS ALSO OBSERVED OVER THE PACIFIC
NORTHWEST. AT THE SURFACE..THE COLD FRONT HAD PUSHED SOUTHEAST
THROUGH THE FORECAST AREA THURSDAY EVENING AND BY 07Z WAS INTO
KANSAS AND EASTERN NEBRASKA. WINDS VARIED BEHIND THE FRONT WITH
SOME LOCATIONS REMAINING MIXED WITH BREEZY CONDITIONS
STILL...WHILE OTHERS HAD DECOUPLED WITH LIGHT WINDS BEING
OBSERVED.
RADAR DID SEE ONGOING ACTIVITY EARLY THIS MORNING WITH A DECENT
BAND OF RAIN JUST NORTH OF THE NEBRASKA/SOUTH DAKOTA BORDER. THIS
BANDING FEATURE WAS OCCURRING WITH FRONTOGENESIS ABOVE 600MB. RADAR
IS INDICATING RAINFALL UP TO A HALF INCH UNDER THIS BAND...BUT
WITH ALL CEILINGS ACROSS THE AREA AT OR ABOVE 8K FEET...THOSE
VALUES ARE WAY OVERDONE. CUSTER SD DID PICK UP 0.08 INCHES EARLIER
SO THINKING EVEN IN THE HIGHER REFLECTIVITY AREAS...A FEW TENTHS
IS PROBABLY THE HIGHEST AMOUNTS. WILL HAVE TO WAIT UNTIL THE
SHOWERS GET OVER A MEASURING STATION THOUGH TO GET GROUND TRUTH.
SHORT TERM...TODAY THROUGH SUNDAY NIGHT
FRONTOGENESIS SIGNAL SHIFTS SOUTH...WITH A SECONDARY BAND LOOKING
TO TAKE OVER TO THE SOUTH OVER THE SANDHILLS. THIS SIGNAL DOES
DECREASE IN STRENGTH AS THE MORNING PROGRESSES AND BY THIS
AFTERNOON...VERY LITTLE FORCING REMAINS OVER THE FORECAST AREA.
DID INCREASE PRECIPITATION OVER THE MORNING HOURS DUE TO HIGHER
COVERAGE...HOWEVER WITH THE DRY BOUNDARY LAYER THAT NEEDS TO BE
PENETRATED...DON/T THINK MUCH OF THE RAIN WILL MAKE IT TO THE
SURFACE. SO BASICALLY LOOKING FOR HIGHER COVERAGE OF LIGHT
QPF...UP TO A TENTH OF AN INCH AT MOST.
CLOUDS WILL SHIFT OUT OF THE MAJORITY OF THE FORECAST AREA BY MID
AFTERNOON. TEMPERATURES TODAY WILL BE MUCH COOLER THAN YESTERDAY
/15 TO 20 DEGREES MOST PLACES/ AS COLDER AIR MOVES SOUTH BEHIND
THE SYSTEM. FOR EXAMPLE...07.00Z UPPER AIR DATA SHOWS A DIFFERENCE
OF 27C ANT KLBF...WITH 18C AT KUNR AND 10C OVER THE UPPER AIR
SITES IN MONTANA. EVEN AFTER THE STRONG PUSH OF COLDER AIR...WITH
CLOUDS MOVING OUT ALLOWING GOOD SUNSHINE IN THE AFTERNOON...AND A
RAPIDLY DRYING BOUNDARY LAYER WILL ALLOW FOR TEMPERATURES TO WARM
INTO THE UPPER 70S AT SOME LOCATIONS.
LOWS TONIGHT STAY A HOT TOPIC...WITH THE COLDEST NIGHT OF THE
SEASON POSSIBLE. MODEL SOLUTIONS SHOWING THE SURFACE HIGH
CENTERED TO THE WEST OF THE FORECAST AREA...INDICATING WINDS WILL
STAY LIGHT RATHER THAN COMPLETELY DROPPING OFF. WOULD LIKE TO SEE
THE HIGH DIRECTLY OVERHEAD FOR WIDESPREAD LOWS IN THE 30S. MADE
MINIMAL CHANGES TO THE FORECAST LOWS...WITH MOST AREAS EXPECTED IN
THE LOW 40S...WITH UPPER 30S IN VALLEYS AND OTHER FAVORED DRAINAGE
LOCATIONS. IF THE PLACEMENT OF THE HIGH CHANGES...THESE VALUES
WILL NEED TO BE REVISITED IN THE NEXT FORECAST PACKAGE.
NORTHERLY FLOW WILL BE IN PLACE SATURDAY...HOWEVER GRADUAL WARMING
ALOFT THROUGH THE DAY WILL ALLOW FOR TEMPERATURES TO WARM DECENTLY
AS DEEP MIXING IS EXPECTED. WENT ON THE HIGH SIDE OF GUIDANCE AS
HAS BEEN THE WAY TO GO LATELY. THIS WOULD BRING HIGHS TO NEAR OR
SLIGHTLY ABOVE NORMAL FOR THE FORECAST AREA. ANOTHER QUITE COOL
NIGHT IS IN STORE FOR SATURDAY NIGHT AS THE SURFACE HIGH SHIFTS
INTO EASTERN NEBRASKA...WITH A COOLER AIRMASS CONTINUING TO SIT
OVER THE REGION. DON/T THINK IT WILL BE AS COLD AS FRIDAY NIGHT AS
THE AIRMASS SHOULD HAVE WARMED SLIGHTLY...BUT LOWS IN THE 40S
CERTAINLY LOOKS LIKELY IN PLACES...ESPECIALLY IN CENTRAL AND
EASTERN NEBRASKA WHICH WILL SIT UNDER THE RIDGE.
SOUTHERLY FLOW WILL RETURN IN FULL FORCE SUNDAY WITH WARMING
TEMPERATURES AND BREEZY WINDS. DEWPOINTS WILL STILL BE QUITE DRY
THOUGH AS LITTLE MOISTURE RETURN IS EXPECTED. 850MB WINDS LOOK TO
RETURN INTO THE 20S ACROSS THE ENTIRE AREA BY SUNDAY
AFTERNOON...SO HIGHS IN THE UPPER 80S AND LOW 90S LOOKS
APPROPRIATE.
LONG TERM...MONDAY THROUGH THURSDAY
HAVE BEEN WATCHING MONDAY FOR THE PAST SEVERAL DAYS AND IT
CONTINUES TO LOOK LIKE IT WILL BE AN ANOMALOUSLY WARM DAY WITH
HIGHS LIKELY IN THE 90S ACROSS THE ENTIRE FORECAST AREA. WITH
CONFIDENCE BUILDING IN THIS OUTCOME...DID RAISE HIGHS ANOTHER
COUPLE DEGREES WITH MID 90S IN PARTS OF THE FORECAST AREA. THERE
IS SUGGESTION FROM SOME MODEL OUTPUT OF UPPER 90S...BUT DIDN/T GO
THAT WARM YET. LOW PRESSURE WILL BE OFF TO THE WEST...BUT LONGER
RANGE MODELS ARE NOT SHOWING A STRONG EASTWARD PUSH OF THE DRYLINE
MONDAY. THIS BEING SAID...DEWPOINTS IN THE UPPER 30S AND 40S WILL
STILL COMBINE WITH TEMPERATURES IN THE 90S TO DROP RELATIVE
HUMIDITY DOWN TO NEAR 15 PERCENT. ALSO...WIND SIGNALS ARE NOT
LOOKING FOR STRONG WINDS...BUT BREEZY CONDITIONS WITH GUSTS AT 20
TO 30 AT TIMES ARE VERY POSSIBLE. FIRE WEATHER WILL BE OF HIGH
CONCERN ON MONDAY DUE TO THESE CONDITIONS.
MODEL SOLUTIONS BEGIN TO DIVERGE AFTER MONDAY SO CONFIDENCE IN THE
LATTER PART OF THE FORECAST DOES GO DOWN. THAT BEING SAID...THERE
IS AGREEMENT IN A SYSTEM MOVING ACROSS THE CENTRAL PLAINS TO BRING
RAIN TO A GOOD PORTION OF THE AREA. THE CONTINUED ISSUE WILL BE
HOW MUCH MOISTURE THERE WILL BE IN THE AREA...IF ENOUGH WILL
RETURN MONDAY AND TUESDAY TO ALLOW FOR SOME WIDESPREAD RAINS. DID
INCLUDE CHANCES FOR RAIN THE THE MIDDLE AND LATE PARTS OF NEXT
WEEK...BUT WITH LOW CONFIDENCE LIMITED THESE CHANCES TO SLIGHT
CHANCES AND ONLY TO THE SOUTHERN COUNTIES. ALSO...A GOOD COOLDOWN
IS BEING INDICATED FOR THE SECOND HALF OF NEXT WEEK. COULD SEE
SEVERAL CONSECUTIVE DAYS OF HIGHS IN THE 70S AND LOW 80S.
AVIATION...
VFR IS EXPECTED ALL AREAS THROUGH TODAY AND TONIGHT.
A MIDLEVEL DISTURBANCE WILL TRAVERSE THE AREA TODAY REDUCING CIGS
TO BKN-OVC070-100 IN PERIODS OF LIGHT RAIN. CLEAR SKIES ARE EXPECTED
TONIGHT.
FIRE WEATHER...
ANOTHER SIGNIFICANT LOW PRESSURE SYSTEM WILL MOVE THROUGH THE NRN
PLAINS THIS WEEKEND AND MONDAY BEFORE A COLD FRONT MOVES THROUGH
TUESDAY.
OPPORTUNITIES FOR HIGH OR EXTREME FIRE DANGER DEVELOP
SATURDAY...SUNDAY AND MONDAY AS THIS LOW DEEPENS ACROSS THE NRN
PLAINS. THE UNCERTAINTY IN THE FIRE WEATHER THREAT RESIDES IN THE
WIND GUST FORECASTS WHICH ARE LIMITED TO JUST TWO MODELS...THE
NAMDNG AND GFS MOSGUIDE DATA.
WIND PROFILES SUGGEST CRITICAL FIRE DANGER SHOULD BE CLOSELY
MONITORED ACROSS NCNTL NEB EAST OF HIGHWAY 83 SATURDAY...WRN AND NRN
NEB SUNDAY AND ALL ZONES MONDAY.
THE NAMDNG DATA SHOWS WIND GUSTS BELOW CRITERIA WHILE THE GFS
MOSGUIDE INDICATES GUSTS EXCEEDING CRITERIA. LATER FORECASTS WILL
MONITOR THIS SITUATION.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS ELKO NV
1056 PM PDT THU SEP 6 2012
.SYNOPSIS...A FEW SHOWERS WILL MOVE ACROSS MUCH OF EASTERN NEVADA
THROUGH EARLY FRIDAY MORNING. FRIDAY AND SATURDAY WILL BE MILD AND
MAINLY DRY WITH THUNDERSTORMS CONFINED TO SOUTH OF HIGHWAY 50.
THUNDERSTORMS WILL INCREASE AGAIN SUNDAY AND MONDAY AS A LOW
PRESSURE SYSTEM MOVES THROUGH.
&&
.UPDATE...ADDED SHOWERS IN THE 06Z-12Z PERIOD...NONE OF THE MODELS
PICKED UP ON THE ACTIVITY. CONVECTION HAS ENDED FOR THE NIGHT SO
REMOVED MENTION OF THUNDERSTORMS.
&&
.PREV DISCUSSION... /ISSUED AT 303 PM /
SYNOPSIS...LOW PRESSURE SYSTEM BRINGS PARTLY TO MOSTLY CLOUDY
SKIES TO NORTHERN AND CENTRAL NEVADA THIS AFTERNOON AND EVENING.
ISOLATED TO SCATTERED THUNDERSTORMS EXPECTED OVER WHITE PINE
COUNTY THIS AFTERNOON. FRIDAY AND SATURDAY WILL BE MILD AND DRY.
NEXT ROUND OF THUNDERSTORMS EXPECTED SUNDAY AFTERNOON.
SHORT TERM...TONIGHT THROUGH FRIDAY. THE REMNANTS OF A PACIFIC
LOW ARE PUSHING ACROSS THE GREAT BASIN BRINGING CLOUD
COVERAGE...SLIGHTLY COOLER TEMPS AND A BAND OF CONVECTION TO
PORTIONS OF CENTRAL NEVADA...NAMELY WHITE PINE COUNTY. NUMEROUS
LIGHTNING STRIKES AND PEA SIZED HAIL HAVE ALREADY BEEN OBSERVED
FROM SOUTHEASTERN ELKO COUNTY TO LUND ALONG A NORTHEAST TO
SOUTHWEST ORIENTED AXIS. THE NAM12 AND HRRR PINGED INTO UNSTABLE
CONDITIONS OVER CENTRAL NEVADA...DEPICTING +400 J/KG OVER WHITE
PINE AND THE EASTERN PORTION OF NORTHERN NYE COINCIDENT WITH
NEGATIVE LIFTED INDICES. MORE CONVECTION ON TAP FOR TONIGHT. THE
NAM12 AND THE GFS40 ARE BOTH DRIER AND SLIGHTLY MORE STABLE
TOMORROW...AS THE RIDGE AXIS BUILDS BACK INTO THE LKN CWA.
LONG TERM...FRIDAY NIGHT THROUGH NEXT THURSDAY. LOW PRESSURE SYSTEM
OFF PACIFIC NORTHWEST COAST. HIGH PRESSURE RIDGE OVER GREAT BASIN.
LONG RANGE MODELS HAVE THE LOW TRACKING NORTH UP THE COAST BEFORE
BEING KICKED NORTHEAST LATE SATURDAY. THIS WILL RESULT IN RELATIVELY
DRY AIR FRIDAY NIGHT AND SATURDAY OVER THE GREAT BASIN WITH RIDGE
AXIS OVERHEAD. WHEN THE LOW KICKS OUT...THE RIDGE FIRST
FLATTENS...THEN DRIFTS EAST ON SUNDAY. THIS WILL OPEN UP MOISTURE
FROM THE SUB-TROPICS TO MOVE NORTH INTO NEVADA...ESPECIALLY OVER THE
SOUTHEAST HALF OF THE FORECAST AREA ON SATURDAY NIGHT THROUGH
TUESDAY.
TEMPS WILL START NEAR 90 AT MOST VALLEY LOCATIONS...DROPPING TO NEAR
NORMAL...THE 80S...BY EARLY IN THE WEEK. LOW TEMPS WILL START IN THE
50S...AND END UP IN THE 40S IN THE POPULATED VALLEY LOCATIONS. A FEW
30S COULD CREEP IN AS SKIES CLEAR OUT MID WEEK.
AVIATION...SCT/BKN MID CLOUDS ACROSS NEVADA THROUGH 03Z FRI. AREA
OF CONVERGING WINDS WILL FIRE UP THUNDERSTORMS IN WHITE PINE COUNTY
AND AFFECT KELY THROUGH SUNSET. SOME SHOWERS MAY AFFECT KEKO. KWMC
AND KTPH SHOULD REMAIN STORM FREE. GUSTY WINDS AT ALL BUT KEKO WILL
REDUCE CLOUD COVER AFTER SUNSET AND ON FRIDAY.
FIRE WEATHER...THIS AFTERNOON THUNDERSTORM ACTIVITY WILL BE
CONCENTRATED OVER 455 AS A WELL DEFINED BAND MOVES THROUGH. THE
PWS HAVE BEEN OVER .80 OF AN INCH IN 455 ON THE
MODELS...SUFFICIENT TO PRODUCE WETTING RAINS. NUMEROUS LIGHTNING
STRIKES ALREADY OBSERVED OVER WHITE PINE COUNTY TODAY. MOSTLY DRY
AND MILD CONDITIONS EXPECTED FRIDAY AND SATURDAY. NEXT WAVE OF
THUNDERSTORM ACTIVITY EXPECTED SUNDAY AND MONDAY AFTERNOONS.
&&
.LKN WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
92/99
AREA FORECAST DISCUSSION
NWS BUFFALO NY
354 PM EDT FRI SEP 7 2012
.SYNOPSIS...
RAPIDLY DEVELOPING LOW PRESSURE WILL TRACK ACROSS THE GREAT LAKES
SATURDAY WHICH WILL BRING HEAVY RAINS AND GUSTY WINDS TO WESTERN NEW
YORK. A COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL SWEEP ACROSS THE
REGION LATE ON SATURDAY USHERING IN MUCH COOLER TEMPERATURES FOR THE
LATTER HALF OF THE WEEKEND AND BEGINNING OF NEXT WEEK.
&&
.NEAR TERM /THROUGH SATURDAY/...
THE GREATEST FORECAST CONCERN IS THE POTENTIAL FOR DAMAGING WINDS ON
SATURDAY. THE GREATEST THREAT IS EAST OF WAYNE/ONTARIO
COUNTIES...AS A STRONG FRONTAL BOUNDARY HAS THE POTENTIAL OF
SPARKING A LINE OF THUNDERSTORMS CAPABLE OF BRINGING STRONG WINDS
ALOFT DOWN TO THE SURFACE. HOWEVER...DEPENDING ON HOW QUICKLY THE
LOW DEEPENS...THIS THREAT MAY EXTEND WEST AND INCLUDE THE BUFFALO
AND ROCHESTER METRO AREAS. FOR THE DETAILS...
THROUGH THIS EVENING...EXPECT MOST AREAS WILL STAY DRY...DESPITE THE
HIGH CLOUDS. THERE WILL BE SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS THE SOUTHERN TIER...BUT FEEL MUCH OF THE 12Z GUIDANCE
(NAM/GFS) ARE OVERDONE IN QPF WITH COURSE MODEL GRIDS SPREADING
SHOWERS INTO WESTERN NEW YORK. THE HRRR HAS THE RIGHT IDEA...BUT
APPEARS OVERDONE LATE AFTERNOON...ESPECIALLY TO THE NORTH NEAR LAKE
ONTARIO. LEAN TOWARD THE DRIER RGEM...WITH SCATTERED SHOWERS AND
THUNDERSTORMS IN THE SOUTHERN TIER TO TAPER OFF...PROVIDING A PERIOD
OF DRY WEATHER FOR MOST OF THE EVENING.
THINGS WILL GET MUCH MORE ACTIVE AFTER THIS...AS LOW PRESSURE
DEVELOPS RAPIDLY ACROSS THE EASTERN LAKES LATE TONIGHT...LIFTING TO
THE QUEBEC/ONTARIO BORDER SATURDAY AFTERNOON. THE RAPIDLY DEEPENING
LOW WILL PUSH A STRONG COLD FRONT ACROSS THE REGION. CONSIDERING THE
TIMEFRAME...MODEL AGREEMENT IS VERY POOR...WITH THE 12Z NAM/RGEM
SIGNIFICANTLY SLOWER THAN THE 12Z GFS...WITH THE UKMET/EUROPEAN
SOMEWHERE IN THE MIDDLE. THE RUC/HRRR TREND ON THE FASTER SIDE OF
GUIDANCE...LEAVING TIMING SOMEWHAT UNCERTAIN. GIVEN THIS...FORECAST
IS A BLEND BETWEEN THE TWO...WITH A LATE MORNING FRONTAL PASSAGE
EXPECTED IN BUFFALO...EARLY AFTERNOON IN ROCHESTER...AND
MID-AFTERNOON IN WATERTOWN. BECAUSE OF MODEL UNCERTAINTY...CAN SEE
THIS TURNING OUT A COUPLE HOURS FASTER OR SLOWER DEPENDING ON HOW
THINGS VERIFY.
THIS PRESENTS A COUPLE OF WIND CONCERNS FOR THE REGION. THE MAJOR
ONE IS THE POTENTIAL FOR CONVECTION WITH THE FRONT...WHICH COULD
TRANSPORT WINDS DOWN TO THE SURFACE. FEEL THIS THREAT IS LESS
FURTHER TO THE WEST AS THE LOW IS DEVELOPING...AND THE FRONT LESS
DEFINED. AS THE LOW DEEPENS...A LINE OF THUNDERSTORMS WILL LIKELY
DEVELOP...AND BECOME MORE ORGANIZED SATURDAY AFTERNOON. DRIVING THIS
WILL BE A STRONG SHORTWAVE...WHICH WILL RACE AND CATCH UP TO THE
SURFACE FRONT. WITH MODEL CONSENSUS AGREEING ON A PRE-FRONTAL WIND
FIELD OF 50 TO 60 KTS AT 850 MB...FEEL THIS POSES A SIGNIFICANT
SEVERE WEATHER THREAT. INSTABILITY WILL BE MODEST AHEAD OF THE
FRONT...BUT GIVEN THE STRONG DYNAMIC LIFT...EXPECT EVEN MODEST
INSTABILITY WILL BE ENOUGH...WITH ANY DAYTIME HEATING A BONUS.
FOLLOWING THIS...SPC HAS PLACED MUCH OF CENTRAL NEW YORK IN A
MODERATE RISK FOR SEVERE WEATHER...WITH STRONG WINDS THE MAIN
CONCERN.
A SECONDARY CONCERN IS SIMPLY THE GRADIENT WINDS WITH THE FRONT. THE
TRACK OF THE LOW IS FAIRLY FAVORABLE FOR PRODUCING STRONG
WINDS...BUT THE LOW IS A BIT LATE TO DEVELOP. THIS SOMEWHAT
MITIGATES THE THREAT FOR DAMAGING WINDS WEST OF ROCHESTER...THOUGH
HIGHER TERRAIN AND THE LAKE ERIE SHORELINE ARE STILL VULNERABLE.
GUSTY WINDS ARE LIKELY EAST OF LAKE ONTARIO ON SATURDAY...WITH GUSTS
LIKELY TO EXCEED 40 MPH EVEN WITHOUT CONVECTION. STRONGEST WINDS
WILL BE IN THE BLACK RIVER VALLEY AND FORT DRUM. ANOTHER THING TO
WATCH IS BECAUSE TREES STILL HAVE LEAVES...THEY WILL BE MORE
SUSCEPTIBLE TO DAMAGE IN GUSTY WINDS.
OTHERWISE...EXPECT STEADY SHOWERS WITH EMBEDDED THUNDERSTORMS TO
ENTER WESTERN NEW YORK AROUND OR SHORTLY AFTER MIDNIGHT. THIS LINE
WILL WORK FROM WEST TO EAST THROUGH SATURDAY MORNING...EXITING TO
THE EAST OF THE CWA SATURDAY AFTERNOON OR EVENING. CONSENSUS QPFS
BRING BETWEEN .50 AND 1.00 INCHES OF RAIN. THE HIGHER AMOUNT ARE
WEST OF ROCHESTER...WHERE THE FRONT SHOULD BE MOVING A BIT SLOWER.
SLOWER MOVING CELLS ARE POSSIBLE LATE TONIGHT IN BUFFALO AND WESTERN
PORTIONS OF THE SOUTHERN TIER...WITH LOCALIZED FLOODING POSSIBLE. AS
THE FRONT ACCELERATES TO THE EAST ON SATURDAY AFTERNOON...RAINFALL
AMOUNTS SHOULD DIMINISH.
OTHERWISE...TEMPERATURES WILL START OFF IN THE 80S LATE
AFTERNOON...BUT DROP RAPIDLY BEHIND THE FRONT. EXPECT SATURDAY TO
START OFF WARM...BUT TO COOL THROUGH THE DAYLIGHT HOURS.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
BY EARLY SATURDAY EVENING...ALL GUIDANCE IS IN GOOD AGREEMENT THAT
THE SURFACE COLD FRONT AND ACCOMPANYING POTENTIAL SQUALL LINE WILL
EITHER HAVE EXITED OR WILL BE IN THE PROCESS OF EXITING OUR FAR
EASTERN ZONES. IN ITS WAKE...AN AREA OF LIMITED WRAPAROUND MOISTURE
WILL PIVOT ACROSS THE AREA SATURDAY EVENING...WHILE A BRISK WESTERLY
FLOW OF MUCH COOLER AIR OVERSPREADS OUR REGION...WITH 850 MB TEMPS
FALLING TO A MUCH MORE AUTUMNAL +6C DURING THE COURSE OF THE NIGHT.
WITH SUCH COOL AIR ALOFT AND SOME CONTRIBUTION FROM THE LAKES LIKELY
AS A RESULT...FEEL THAT MOST AREAS SHOULD SEE SOME SCATTERED SHOWERS
FOR A TIME SUNDAY EVENING...BEFORE FURTHER SYNOPTIC-SCALE DRYING
LEADS TO THE DEMISE OF THIS ACTIVITY OVERNIGHT. THE EXCEPTIONS TO
THIS WILL BE IN AREAS MORE IMMEDIATELY DOWNWIND OF THE LAKES...WHERE
CONTINUED LAKE-DRIVEN INSTABILITY WILL KEEP SHOWER CHANCES ONGOING
THROUGH THE NIGHT. THIS SAID...THE RELATIVELY SHALLOW MOISTURE FIELD
THAT WILL BE IN PLACE PRECLUDES GOING WITH ANYTHING MORE THAN
MID-HIGH CHANCE POPS EVEN IN THESE AREAS.
ON SUNDAY...THE CORE OF THE LARGE-SCALE UPPER TROUGH WILL SETTLE
ACROSS THE REGION. WITH DAYTIME HEATING...THE AREA OF BEST
INSTABILITY WILL TRANSITION FROM LAKE TO LAND...WITH ANY SCATTERED
LAKE EFFECT SHOWERS TRANSITIONING TO MORE GENERAL DIURNALLY-DRIVEN
SHOWERS THAT WILL ALSO CONCENTRATED MORE OVER LAND. THIS SAID...
THESE WILL AGAIN ONLY BE WORTH SOME LOW CHANCE POPS GIVEN THE VERY
LIMITED AMOUNTS OF MOISTURE THAT WILL AGAIN BE IN PLACE.
SUNDAY NIGHT...ANY DIURNALLY-DRIVEN SCATTERED SHOWERS SHOULD END
RATHER QUICKLY WITH THE LOSS OF HEATING SUNDAY EVENING. ANY WEAK
LAKE-DRIVEN SHOWERS ONGOING EAST-SOUTHEAST OF THE LAKES SUNDAY
EVENING WILL ALSO TEND TO SHIFT SOUTHWARD AND FALL APART WITH TIME
AS THE FLOW TURNS MORE NORTHWESTERLY AND SURFACE RIDGING/EVEN DRIER
AIR BUILDS EAST FROM THE CENTRAL GREAT LAKES. BY MONDAY MORNING...
EXPECT ONLY SOME LEFTOVER LAKE EFFECT CLOUDS AND PERHAPS AN ISOLATED
SHOWER OR TWO SOUTHEAST OF LAKE ONTARIO. ANY SUCH ACTIVITY WILL THEN
BE QUICKLY SQUELCHED BY THE ADVANCING RIDGE AND DIURNAL INFLUENCES
MONDAY MORNING...WITH DRY AND FAIR WEATHER THEN EXPECTED THROUGH THE
REMAINDER OF THE SHORT TERM PERIOD.
WITH REGARD TO TEMPS...THE MUCH COOLER AIRMASS ARRIVING SATURDAY
NIGHT WILL PERSIST THROUGH SUNDAY AND MONDAY...WHILE PROVIDING US
WITH THE COOLEST TEMPERATURES SO FAR OF THIS VERY YOUNG
METEOROLOGICAL FALL SEASON. LOOK FOR LOWS IN THE LOWER HALF OF THE
50S SATURDAY NIGHT...WITH 850 MB TEMPS OF +6C TO +8C ONLY
SUPPORTING HIGHS IN THE MID 60S TO LOWER 70S ON SUNDAY...WITH THE
COOLER READINGS FOUND ACROSS THE HIGHER TERRAIN. SIMILAR HIGH TEMPS
CAN BE EXPECTED ON MONDAY...WHILE LOWS SUNDAY NIGHT AND MONDAY NIGHT
WILL LIKELY DIP INTO THE 45 TO 50 RANGE...WITH SOME LOWER 40S FOUND
ACROSS INTERIOR PORTIONS OF THE SOUTHERN TIER AND NORTH COUNTRY.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
THE FIRST HALF OF THE EXTENDED PERIOD WILL FEATURE CONTINUED DRY
WEATHER AND RETURN TO WARMER TEMPERATURES AS SURFACE RIDGING SLIDES
EAST TO THE ATLANTIC COAST...WHILE UPPER LEVEL RIDGING OVER THE
PLAINS STATES FLATTENS AND PUSHES EAST INTO THE GREAT LAKES. A BLEND
OF THE GFS AND ECMWF SUGGESTS 850 MB TEMPS RECOVERING TO +7C TO +9C
ON TUESDAY AND TO THE +12C TO +14C RANGE ON WEDNESDAY...WHICH SHOULD
SUPPORT HIGHS RECOVERING BACK INTO THE LOWER 70S ON TUESDAY...AND THE
UPPER 70S/NEAR 80 ON WEDNESDAY.
AFTER THAT...THE AXIS OF THE UPPER RIDGE SHOULD CONTINUE TO FLATTEN
AND SLIDE EAST OFF THE ATLANTIC COAST AS THE NEXT BROAD UPPER LEVEL
TROUGH GRADUALLY DIGS SOUTHEAST INTO THE GREAT LAKES. THIS SAID...
THE MEDIUM RANGE GUIDANCE CONTINUES TO DIFFER ON THE RATE AT WHICH
THIS PROCESS OCCURS...WITH THE GFS SWINGING AN ASSOCIATED WEAK COLD
FRONT INTO THE AREA ON FRIDAY...AND THE ECMWF REMAINING ABOUT 18-24
HOURS FASTER...ALTHOUGH THIS LATTER MODEL ALSO SPITS OUT MUCH LESS
IN THE WAY OF PRECIP.
GIVEN THE ABOVE FACTORS AND WHAT SHOULD BE A TENDENCY FOR THIS FRONT
TO SLOW DOWN AS IT BECOMES ORIENTED INCREASING PARALLEL TO THE
LARGE-SCALE UPPER LEVEL FLOW...WILL KEEP THURSDAY DRY FOR NOW...THEN
INTRODUCE SOME VERY LOW-END CHANCE POPS FOR FRIDAY. IN ADVANCE OF
THE BOUNDARY...850 MB TEMPS OF +12C TO +14C SHOULD PERSIST...
SUPPORTING HIGHS IN THE UPPER 70S TO AROUND 80 ON BOTH THURSDAY AND
FRIDAY.
&&
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
THROUGH 06Z TONIGHT...EXPECT MAINLY VFR CONDITIONS. THE MAIN CONCERN
FOR AVIATION FROM 18Z FRI THROUGH 06Z SAT WILL BE SCATTERED
THUNDERSTORMS...WHICH WILL MAINLY BE ACROSS THE SOUTHERN TIER THIS
AFTERNOON. THUNDERSTORMS MAY IMPACT JHW...WITH THE CHANCE FOR
THUNDERSTORMS ELSEWHERE TOO SMALL TO WARRANT A MENTION IN THE TAFS.
AFTER THIS...DEEPENING LOW PRESSURE WILL PUSH A STRONG FRONTAL
BOUNDARY ACROSS THE REGION SATURDAY MORNING. WINDS ALOFT WILL
INCREASE AHEAD OF THE FRONT. THIS MAY RESULT IN LLWS AT SOME
LOCATIONS...WHERE THESE WINDS DON/T MIX DOWN. THERE WILL ALSO BE
SHOWERS AND THUNDERSTORMS WITH THE FRONT...WHICH MAY LOWER VSBY AND
CIGS IN BRIEF PERIODS OF HEAVY RAIN. ANOTHER CONCERN WILL BE STRONG
WINDS WITH THUNDERSTORMS ALONG THE FRONT. THIS COULD HAVE A BRIEF
BUT SIGNIFICANT IMPACT ON TAF SITES.
THE FRONT WILL PUSH EASTWARD SATURDAY AFTERNOON...EXITING EAST OF
ART BY 00Z SUN.
OUTLOOK...
SATURDAY NIGHT AND SUNDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
MONDAY THROUGH THURSDAY...MAINLY VFR. PATCHY VALLEY FOG POSSIBLE
EARLY EACH MORNING.
&&
.MARINE...
OPTED TO HOIST GALES ON BOTH OF THE LAKES. FEEL FAIRLY CONFIDENT
LAKE ONTARIO WILL REACH GALE CRITERIA ALONG AND BEHIND THE FRONT ON
SATURDAY. LAKE ERIE WILL BE A BIT MORE MARGINAL...BUT GIVEN THE GOOD
POTENTIAL FOR A BRIEF PERIOD OF GALE CRITERIA GUSTS WITH THE
FRONT...HAVE OPTED TO ISSUE THE GALES FOR LAKE ERIE AS WELL. FOR
NOW...WENT WITH SMALL CRAFT ADVISORIES ON THE RIVERS...WHERE MIXING
WILL NOT BE AS GOOD.
SIGNIFICANTLY COLDER AIR WILL FILTER INTO THE REGION BEHIND THE COLD
FRONT...BRINGING AN INCREASED POTENTIAL FOR WATERSPOUTS FOR THE
LATTER HALF OF THE WEEKEND INTO THE EARLY PART OF NEXT WEEK. IN
ADDITION A PROLONGED PERIOD OF BRISK WESTERLY WINDS WILL LIKELY MEAN
AN EXTENDED PERIOD OF SMALL CRAFT ADVISORY CONDITIONS ON THE LAKES.
&&
.CLIMATE...
AN EARLY WARM SPRING AND CONTINUED WARMTH THROUGH THE SUMMER HAS
LED TO MANY DAYS THAT HAVE REACHED 80F ACROSS WESTERN AND NORTH
CENTRAL NEW YORK. BELOW IS A LIST OF THE NUMBER OF DAYS IN THE
CALENDAR YEAR THAT HAVE REACHED 80 DEGREES OR GREATER. THE 2012
TOTAL WILL INCREASE AS WE REACH ADDITIONAL 80F DAYS THROUGH THE
EARLY FALL.
BUFFALO (SINCE 1871)
1 83 1949
2 82 1959
3 78 2012 (THROUGH FRI 9/7)
4 77 1991
5 76 1955
6 75 1947
75 1983
75 2005
9 73 2011
ROCHESTER (SINCE 1871)
1 91 1959
2 86 2007
3 83 2012 (THROUGH FRI 9/7)
83 2002
83 1973
83 1949
83 1947
8 81 1991
9 80 2005
80 1921
...
21 75 2011
WATERTOWN (SINCE 1949)
1 75 1949
2 73 1959
3 70 2012 (THROUGH FRI 9/7)
4 68 1955
5 67 1973
...
9 60 2011
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 8 AM TO 8 PM EDT SATURDAY FOR LEZ020.
GALE WARNING FROM 8 AM TO 8 PM EDT SATURDAY FOR LEZ040-041.
SMALL CRAFT ADVISORY FROM 8 AM TO 8 PM EDT SATURDAY
FOR LOZ030.
GALE WARNING FROM 11 AM TO 11 PM EDT SATURDAY FOR
LOZ042>045-062>065.
SMALL CRAFT ADVISORY FROM 11 AM TO 11 PM EDT SATURDAY
FOR SLZ022-024.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL/WOOD
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...APFFEL
MARINE...APFFEL/JJR
CLIMATE...THOMAS/JJR
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1046 AM EDT FRI SEP 7 2012
.SYNOPSIS...
EXPECT A FAIR AMOUNT OF SUNSHINE TODAY ALONG WITH ABOVE NORMAL
TEMPERATURES AND SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS
POSSIBLE. CLOUD COVER WILL INCREASE TONIGHT AND THE WEATHER WILL
TURN MORE UNSETTLED BY SATURDAY MORNING AS A RAPIDLY DEVELOPING LOW
TRACKS ACROSS THE GREAT LAKES BRINGING HEAVY RAIN AND GUSTY WINDS TO
THE REGION ON SATURDAY. A COLD FRONT ASSOCIATED WITH THIS SYSTEM
WILL SWEEP ACROSS THE REGION LATE ON SATURDAY USHERING IN MUCH
COOLER TEMPERATURES FOR THE LATTER HALF OF THE WEEKEND AND BEGINNING
OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
A STALLED FRONT TO THE WEST WILL LEAVE WESTERN NEW YORK ON THE
WARM AND MUGGY SIDE OF THE BOUNDARY. HIGHS SHOULD BE SIMILAR TO A
TAD WARMER THAN YESTERDAY. A BLEND OF THE BIAS CORRECTED
SREF...LAV GUIDANCE...AND THE 12Z BUFFALO SUGGEST HIGHS WILL BE IN
THE LOWER TO MID 80S TODAY.
THE MOIST AND UNSTABLE AIRMASS IN PLACE ACROSS THE REGION WILL
ONCE AGAIN CREATE THE POTENTIAL FOR THE DEVELOPMENT OF ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON WITH THE MOST
LIKELY FOCUS FOR SAID ACTIVITY BEING ACROSS THE GENESEE VALLY AND
FINGER LAKES...AWAY FROM THE STABILIZING INFLUENCE OF THE LAKES.
WITH NO DISTINCT LARGE-SCALE FOCUS FOR CONVECTION...EXPECT LAKE
BREEZE BOUNDARIES WILL BE THE MAIN FOCUS FOR ANY CONVECTION WHICH
DEVELOPS. FEEL THE HRRR HAS THE RIGHT IDEA IN THIS...THOUGH IT
MAY BE OFF SLIGHTLY ON THE POSITION OF THE BOUNDARIES. SEVERE
WEATHER POTENTIAL IS MINIMAL GIVEN FAIRLY WEAK WINDS BELOW
850MB...HOWEVER A STRONG PULSE THUNDERSTORM CANNOT BE RULED OUT.
ANY SHOWERS OR THUNDERSTORMS SHOULD HOLD OFF UNTIL MID- AFTERNOON.
THE FOCUS OF ANY LINGERING SHOWER AND THUNDERSTORM ACTIVITY SHOULD
SHIFT NORTH TOWARDS CANADA THIS EVENING AS THE STATIONARY FRONT LIFTS
NORTH AS A WARM FRONT AHEAD OF A RAPIDLY DEVELOPING LOW PRESSURE
SYSTEM MOVING OUT OF THE MIDWEST INTO THE LOWER GREAT LAKES.
STRENGTHENING SOUTHERLY FLOW AHEAD OF THIS LOW WILL ADVECT EVEN
WARMER AIR INTO THE REGION WITH 850MB TEMPS SURGING TO +16 TO
+18C...RESULTING IN A SULTRY LATE SUMMER NIGHT ACROSS THE REGION
WITH LOWS ONLY DIPPING INTO THE UPPER 60S ALONG THE LAKE PLAINS WITH
MID 60S ACROSS HIGHER ELEVATIONS INLAND. THE CHANCE FOR SHOWERS AND
THUNDERSTORMS WILL ONCE AGAIN INCREASE ACROSS THE NIAGARA FRONTIER
AFTER MIDNIGHT AHEAD OF THE APPROACHING COLD FRONT.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AT THE START OF THE PERIOD ON SATURDAY A VERY DYNAMIC AND MOISTURE
LADEN SYSTEM WILL BRING ANOTHER ROUND OF WIDESPREAD RAINFALL TO THE
REGION. VERY STRONG DYNAMICS WILL COME INTO PLAY WITH STRONG HEIGHT
FALLS AND DPVA AND STRONG UPPER LEVEL DIVERGENCE IN THE RIGHT
ENTRANCE REGION OF A 120+ KNOT UPPER LEVEL JET. THE FRONTAL WAVE
WILL ALSO INDUCE A STRONG DIFFERENTIAL THERMAL ADVECTION PATTERN AND
FORCE A STRONG RIBBON OF FRONTOGENESIS ALONG THE COLD FRONT. THE
SYSTEM WILL CAPTURE A PLUME OF DEEPER MOISTURE AS IT ROUNDS THE BASE
OF THE TROUGH...WITH PWAT RISING TO 1.5 TO 1.75 INCHES. THE QUALITY
OF FORCING AND MOISTURE COMING INTO PLAY WILL BRING ANOTHER PERIOD
OF MODERATE OR EVEN HEAVY RAINFALL TO THE REGION...WITH QPF
POTENTIAL OF AROUND AN INCH POSSIBLE...WITH LOCALLY HIGHER AMOUNTS
WHERE EMBEDDED CONVECTION TRAINS.
NAM/SREF/CMC MODELS ARE SHOWING A SLIGHTLY SLOWER SCENARIO WITH THE
PREFRONTAL CONVECTION TO ARRIVE DURING THE DAY ON SATURDAY RATHER
THAN EARLIER ARRIVAL DURING LATE FRIDAY NIGHT AS DEPICTED BY GFS.
WILL CONTINUE WITH THE 100 PERCENT POP GRIDS BUT HAVE A LITTLE MORE
RESOLUTION ALONG AND IN ADVANCE OF THE FRONTAL BOUNDARY.
WHILE SATURDAY WILL BE A WET DAY ACROSS THE REGION...LATE SATURDAY
AND AT LEAST THE FIRST HALF OF SATURDAY NIGHT COULD BE QUITE WINDY
AS WELL. THIS WILL ESPECIALLY BE THE CASE OVER THE FAR WESTERN
COUNTIES AND IN PARTICULAR...THE CORRIDOR FROM BUFFALO AND THE LAKE
ERIE SHORE TO ROCHESTER. EXPECT TO SEE A RISE IN WINDS AND GUSTS
IMMEDIATELY FOLLOWING FROPA...AND ESPECIALLY FROM THE NIAGARA
FRONTIER TO THE LOWER GENESEE VALLEY...AFFECTING THE BUF/IAG/ROC
METRO AREAS. HAVE BACKED OFF A BIT ON THE INTENSITY OF THE WINDS AS
MODELS ARE NOT EXPLICITLY DEPICTING ADVISORY CRITERIA SURFACE WINDS
BUT THERE WILL REMAIN THE RISK OF HIGHER TURBULENT GUSTS WITHIN THE
BRISK GRADIENT WINDS DURING LATE SATURDAY AFTERNOON AND EVENING.
LATER SATURDAY NIGHT AND SUNDAY ANOTHER STRONG SHORTWAVE WILL ROUND
THE BASE OF THE TROUGH WITH 850MB TEMPS BOTTOMING OUT AROUND +4C.
MOISTURE WILL BE LIMITED...BUT COLD AIR ALOFT AND SOME ADDITION OF
MOISTURE FROM THE LAKES WILL PRODUCE SCATTERED SHOWERS. SUNDAY
MORNING MOST OF THE SHOWERS MAY BE PURELY LAKE EFFECT SOUTHEAST OF
THE LAKES. BY AFTERNOON THE GREATER INSTABILITY SHOULD FOCUS ACROSS
THE LAND WITH LESS ACTIVITY OVER THE LAKES. SUNDAY NIGHT ALL OF THIS
WILL GRADUALLY END AS SURFACE HIGH PRESSURE AND DRIER AIR BUILD INTO
THE GREAT LAKES.
THE COOLEST TEMPERATURES OF THIS EARLY FALL SEASON WILL ARRIVE OVER
THE WEEKEND. TEMPS MAY BRIEFLY TOUCH THE LOWER 70S SATURDAY MORNING
ESPECIALLY ACROSS CENTRAL NY BEFORE THE RAIN ARRIVES. BY SUNDAY
HIGHS WILL ONLY BE IN THE UPPER 60S AT LOWER ELEVATIONS AND LOW TO
MID 60S ACROSS HIGHER TERRAIN.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BUILD INTO THE OHIO VALLEY AND GREAT LAKES MONDAY
WITH A RETURN TO SUNSHINE. TEMPERATURES WILL STILL BE COOL HOWEVER
WITH A CHILLY AIRMASS IN PLACE. EXPECT HIGHS IN THE UPPER 60S ACROSS
LOWER ELEVATIONS AND LOW TO MID 60S AT HIGHER TERRAIN. MONDAY NIGHT
SHOULD BE THE COOLEST NIGHT OF THE STRETCH AS HIGH PRESSURE SETTLES
DIRECTLY OVERHEAD WITH IDEAL RADIATIONAL COOLING CONDITIONS. EXPECT
LOWER 50S ON THE LAKE PLAINS AND PLENTY OF 40S INLAND...WITH A FEW
OF THE COOLER SOUTHERN TIER VALLEYS AND TUG HILL REGION DIPPING INTO
THE UPPER 30S.
TUESDAY THROUGH WEDNESDAY HIGH PRESSURE WILL SLIDE TO THE EAST COAST
AND THE PATTERN WILL REMAIN PROGRESSIVE...WITH THE WESTERN RIDGE
FLATTENING AND HEADING EAST. THIS WILL BRING A STEADY WARM-UP WITH
HIGHS BACK INTO THE 70S...AND POSSIBLY NEAR 80 BY WEDNESDAY. DRY
WEATHER WILL CONTINUE THROUGH THE PERIOD WITH PLENTY OF SUNSHINE.
BY THURSDAY THE NEW 12Z ECMWF LEANS A WEAK COLD FRONT INTO THE LOWER
LAKES...BUT THE 12Z GFS IS MUCH SLOWER WITH THIS FRONT KEEPING IT
WELL TO OUR WEST.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS WILL THEN PREVAIL THROUGH THE TAF PERIOD. THERE IS
A POSSIBILITY OF SHOWERS AND THUNDERSTORMS DEVELOPING THIS
AFTERNOON WITH THE FOCUS BEING ACROSS THE GENESEE VALLEY AND
FINGER LAKES. ANY CONVECTION THIS AFTERNOON SHOULD WEAKEN AND/OR
LIFT NORTH THIS EVENING AS THE STALLED OUT FRONTAL BOUNDARY AIDING
THE DEVELOPMENT OF THESE SHRA/TSRA LIFTS NORTH INTO CANADA AS A
WARM FRONT.
THE MAIN FOCUS WILL THEN SHIFT TO THE RAPIDLY DEVELOPING LOW
PRESSURE SYSTEM THAT IS FORECAST TO TRACK ACROSS THE LOWER GREAT
LAKES FRIDAY NIGHT AND SATURDAY BRINGING WIDESPREAD HEAVY RAIN WITH
WIDESPREAD MVFR/IFR CONDITIONS AND STRONG WINDS. THE LEADING EDGE OF
THIS FRONTAL BAND IS EXPECTED TO BEGIN TO EDGE INTO THE NIAGARA
FRONTIER AND WESTERN SOUTHERN TIER AFTER 09Z SATURDAY MORNING WITH
CONDITIONS CONTINUING TO DETERIORATE THROUGH THE MORNING ON
SATURDAY...NEAR AND AFTER THE END OF THE CURRENT TAF PERIOD. IN
ADDITION...THE ARRIVAL OF A 35-40KT LOW LEVEL JET MAY POSE LLWS
ISSUES AFTER 09Z HOWEVER THIS WILL BE DEPENDENT ON HOW STRONG THE
NOCTURNAL INVERSION SETS UP TONIGHT.
OUTLOOK...
SATURDAY...MVFR/IFR IN RAIN AND SCATTERED THUNDERSTORMS.
SUNDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
MONDAY THROUGH WEDNESDAY...VFR.
&&
.MARINE...
LIGHT WINDS AND WAVES WILL PREVAIL ON THE LAKES TODAY AND THIS
EVENING AS HIGH PRESSURE SLOWLY RETREATS TOWARDS THE EAST COAST.
CONDITIONS ON THE LAKES WILL DETERIORATE FROM WEST TO EAST LATER
TONIGHT AS A RAPIDLY DEVELOPING LOW PRESSURE SYSTEM TRACKS FROM THE
MIDWEST ACROSS THE LOWER GREAT LAKES. SOUTHERLY WINDS WILL FRESHEN
AHEAD OF THIS LOW LATE FRIDAY NIGHT/EARLY SATURDAY MORNING AND WILL
TRANSITION TO STRONGER WEST/SOUTHWESTERLY WINDS LATER ON SATURDAY AS
A COLD FRONT SWEEPS ACROSS THE LAKES. A BRIEF PERIOD OF GALES MAY BE
POSSIBLE IMMEDIATELY IN THE WAKE OF THE FRONT...HOWEVER THERE IS
STILL SOME UNCERTAINTY AS TO WHERE EXACTLY THE STRONGEST WINDS WILL
LINE UP WITH RELATION TO THE LAKES.
SIGNIFICANTLY COLDER AIR WILL FILTER INTO THE REGION BEHIND THE COLD
FRONT...BRINGING AN INCREASED POTENTIAL FOR WATERSPOUTS FOR THE
LATTER HALF OF THE WEEKEND INTO THE EARLY PART OF NEXT WEEK. IN
ADDITION A PROLONGED PERIOD OF BRISK WESTERLY WINDS WILL LIKELY MEAN
AN EXTENDED PERIOD OF SMALL CRAFT ADVISORY CONDITIONS ON THE LAKES.
&&
.CLIMATE...
AN EARLY WARM SPRING AND CONTINUED WARMTH THROUGH THE SUMMER HAS
LED TO MANY DAYS THAT HAVE REACHED 80F ACROSS WESTERN AND NORTH
CENTRAL NEW YORK. BELOW IS A LIST OF THE NUMBER OF DAYS IN THE
CALENDAR YEAR THAT HAVE REACHED 80 DEGREES OR GREATER. THE 2012
TOTAL WILL INCREASE AS WE REACH ADDITIONAL 80F DAYS THROUGH THE
EARLY FALL.
BUFFALO (SINCE 1871)
1 83 1949
2 82 1959
3 77 1991
77 2012 (THROUGH THU 9/6)
5 76 1955
6 75 1947
75 1983
75 2005
9 73 2011
ROCHESTER (SINCE 1871)
1 91 1959
2 86 2007
3 83 2002
83 1973
83 1949
83 1947
7 82 2012 (THROUGH THU 9/6)
8 81 1991
9 80 2005
80 1921
...
21 75 2011
WATERTOWN (SINCE 1949)
1 75 1949
2 73 1959
3 69 2012 (THROUGH THU 9/6)
4 68 1955
5 67 1973
...
9 60 2011
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...WOOD
NEAR TERM...APFFEL/WOOD
SHORT TERM...WCH
LONG TERM...HITCHCOCK
AVIATION...APFFEL/WOOD
MARINE...WOOD
CLIMATE...THOMAS/JJR
AREA FORECAST DISCUSSION
NWS BUFFALO NY
941 AM EDT FRI SEP 7 2012
.SYNOPSIS...
EXPECT A FAIR AMOUNT OF SUNSHINE TODAY ALONG WITH ABOVE NORMAL
TEMPERATURES AND SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS
POSSIBLE. CLOUD COVER WILL INCREASE TONIGHT AND THE WEATHER WILL
TURN MORE UNSETTLED BY SATURDAY MORNING AS A RAPIDLY DEVELOPING LOW
TRACKS ACROSS THE GREAT LAKES BRINGING HEAVY RAIN AND GUSTY WINDS TO
THE REGION ON SATURDAY. A COLD FRONT ASSOCIATED WITH THIS SYSTEM
WILL SWEEP ACROSS THE REGION LATE ON SATURDAY USHERING IN MUCH
COOLER TEMPERATURES FOR THE LATTER HALF OF THE WEEKEND AND BEGINNING
OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
ANY LINGERING FOG WILL BURN OFF QUICKLY...GIVING WAY TO MOSTLY
SUNNY SKIES BY LATE MORNING. A STALLED FRONT TO THE WEST WILL
LEAVE WESTERN NEW YORK ON THE WARM AND MUGGY SIDE OF THE BOUNDARY.
HIGHS SHOULD BE SIMILAR TO A TAD WARMER THAN YESTERDAY. A BLEND OF
THE BIAS CORRECTED SREF...LAV GUIDANCE...AND THE 12Z BUFFALO
SUGGEST HIGHS WILL BE IN THE LOWER TO MID 80S TODAY.
THE MOIST AND UNSTABLE AIRMASS IN PLACE ACROSS THE REGION WILL
ONCE AGAIN CREATE THE POTENTIAL FOR THE DEVELOPMENT OF ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON WITH THE MOST
LIKELY FOCUS FOR SAID ACTIVITY BEING ACROSS THE GENESEE VALLY AND
FINGER LAKES...AWAY FROM THE STABILIZING INFLUENCE OF THE LAKES.
WITH NO DISTINCT LARGE-SCALE FOCUS FOR CONVECTION...EXPECT LAKE
BREEZE BOUNDARIES WILL BE THE MAIN FOCUS FOR ANY CONVECTION WHICH
DEVELOPS. FEEL THE HRRR HAS THE RIGHT IDEA IN THIS...THOUGH IT
MAY BE OFF SLIGHTLY ON THE POSITION OF THE BOUNDARIES. SEVERE
WEATHER POTENTIAL IS MINIMAL GIVEN FAIRLY WEAK WINDS BELOW
850MB...HOWEVER A STRONG PULSE THUNDERSTORM CANNOT BE RULED OUT.
ANY SHOWERS OR THUNDERSTORMS SHOULD HOLD OFF UNTIL MID- AFTERNOON.
THE FOCUS OF ANY LINGERING SHOWER AND THUNDERSTORM ACTIVITY SHOULD
SHIFT NORTH TOWARDS CANADA THIS EVENING AS THE STATIONARY FRONT LIFTS
NORTH AS A WARM FRONT AHEAD OF A RAPIDLY DEVELOPING LOW PRESSURE
SYSTEM MOVING OUT OF THE MIDWEST INTO THE LOWER GREAT LAKES.
STRENGTHENING SOUTHERLY FLOW AHEAD OF THIS LOW WILL ADVECT EVEN
WARMER AIR INTO THE REGION WITH 850MB TEMPS SURGING TO +16 TO
+18C...RESULTING IN A SULTRY LATE SUMMER NIGHT ACROSS THE REGION
WITH LOWS ONLY DIPPING INTO THE UPPER 60S ALONG THE LAKE PLAINS WITH
MID 60S ACROSS HIGHER ELEVATIONS INLAND. THE CHANCE FOR SHOWERS AND
THUNDERSTORMS WILL ONCE AGAIN INCREASE ACROSS THE NIAGARA FRONTIER
AFTER MIDNIGHT AHEAD OF THE APPROACHING COLD FRONT.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AT THE START OF THE PERIOD ON SATURDAY A VERY DYNAMIC AND MOISTURE
LADEN SYSTEM WILL BRING ANOTHER ROUND OF WIDESPREAD RAINFALL TO THE
REGION. VERY STRONG DYNAMICS WILL COME INTO PLAY WITH STRONG HEIGHT
FALLS AND DPVA AND STRONG UPPER LEVEL DIVERGENCE IN THE RIGHT
ENTRANCE REGION OF A 120+ KNOT UPPER LEVEL JET. THE FRONTAL WAVE
WILL ALSO INDUCE A STRONG DIFFERENTIAL THERMAL ADVECTION PATTERN AND
FORCE A STRONG RIBBON OF FRONTOGENESIS ALONG THE COLD FRONT. THE
SYSTEM WILL CAPTURE A PLUME OF DEEPER MOISTURE AS IT ROUNDS THE BASE
OF THE TROUGH...WITH PWAT RISING TO 1.5 TO 1.75 INCHES. THE QUALITY
OF FORCING AND MOISTURE COMING INTO PLAY WILL BRING ANOTHER PERIOD
OF MODERATE OR EVEN HEAVY RAINFALL TO THE REGION...WITH QPF
POTENTIAL OF AROUND AN INCH POSSIBLE...WITH LOCALLY HIGHER AMOUNTS
WHERE EMBEDDED CONVECTION TRAINS.
NAM/SREF/CMC MODELS ARE SHOWING A SLIGHTLY SLOWER SCENARIO WITH THE
PREFRONTAL CONVECTION TO ARRIVE DURING THE DAY ON SATURDAY RATHER
THAN EARLIER ARRIVAL DURING LATE FRIDAY NIGHT AS DEPICTED BY GFS.
WILL CONTINUE WITH THE 100 PERCENT POP GRIDS BUT HAVE A LITTLE MORE
RESOLUTION ALONG AND IN ADVANCE OF THE FRONTAL BOUNDARY.
WHILE SATURDAY WILL BE A WET DAY ACROSS THE REGION...LATE SATURDAY
AND AT LEAST THE FIRST HALF OF SATURDAY NIGHT COULD BE QUITE WINDY
AS WELL. THIS WILL ESPECIALLY BE THE CASE OVER THE FAR WESTERN
COUNTIES AND IN PARTICULAR...THE CORRIDOR FROM BUFFALO AND THE LAKE
ERIE SHORE TO ROCHESTER. EXPECT TO SEE A RISE IN WINDS AND GUSTS
IMMEDIATELY FOLLOWING FROPA...AND ESPECIALLY FROM THE NIAGARA
FRONTIER TO THE LOWER GENESEE VALLEY...AFFECTING THE BUF/IAG/ROC
METRO AREAS. HAVE BACKED OFF A BIT ON THE INTENSITY OF THE WINDS AS
MODELS ARE NOT EXPLICITLY DEPICTING ADVISORY CRITERIA SURFACE WINDS
BUT THERE WILL REMAIN THE RISK OF HIGHER TURBULENT GUSTS WITHIN THE
BRISK GRADIENT WINDS DURING LATE SATURDAY AFTERNOON AND EVENING.
LATER SATURDAY NIGHT AND SUNDAY ANOTHER STRONG SHORTWAVE WILL ROUND
THE BASE OF THE TROUGH WITH 850MB TEMPS BOTTOMING OUT AROUND +4C.
MOISTURE WILL BE LIMITED...BUT COLD AIR ALOFT AND SOME ADDITION OF
MOISTURE FROM THE LAKES WILL PRODUCE SCATTERED SHOWERS. SUNDAY
MORNING MOST OF THE SHOWERS MAY BE PURELY LAKE EFFECT SOUTHEAST OF
THE LAKES. BY AFTERNOON THE GREATER INSTABILITY SHOULD FOCUS ACROSS
THE LAND WITH LESS ACTIVITY OVER THE LAKES. SUNDAY NIGHT ALL OF THIS
WILL GRADUALLY END AS SURFACE HIGH PRESSURE AND DRIER AIR BUILD INTO
THE GREAT LAKES.
THE COOLEST TEMPERATURES OF THIS EARLY FALL SEASON WILL ARRIVE OVER
THE WEEKEND. TEMPS MAY BRIEFLY TOUCH THE LOWER 70S SATURDAY MORNING
ESPECIALLY ACROSS CENTRAL NY BEFORE THE RAIN ARRIVES. BY SUNDAY
HIGHS WILL ONLY BE IN THE UPPER 60S AT LOWER ELEVATIONS AND LOW TO
MID 60S ACROSS HIGHER TERRAIN.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BUILD INTO THE OHIO VALLEY AND GREAT LAKES MONDAY
WITH A RETURN TO SUNSHINE. TEMPERATURES WILL STILL BE COOL HOWEVER
WITH A CHILLY AIRMASS IN PLACE. EXPECT HIGHS IN THE UPPER 60S ACROSS
LOWER ELEVATIONS AND LOW TO MID 60S AT HIGHER TERRAIN. MONDAY NIGHT
SHOULD BE THE COOLEST NIGHT OF THE STRETCH AS HIGH PRESSURE SETTLES
DIRECTLY OVERHEAD WITH IDEAL RADIATIONAL COOLING CONDITIONS. EXPECT
LOWER 50S ON THE LAKE PLAINS AND PLENTY OF 40S INLAND...WITH A FEW
OF THE COOLER SOUTHERN TIER VALLEYS AND TUG HILL REGION DIPPING INTO
THE UPPER 30S.
TUESDAY THROUGH WEDNESDAY HIGH PRESSURE WILL SLIDE TO THE EAST COAST
AND THE PATTERN WILL REMAIN PROGRESSIVE...WITH THE WESTERN RIDGE
FLATTENING AND HEADING EAST. THIS WILL BRING A STEADY WARM-UP WITH
HIGHS BACK INTO THE 70S...AND POSSIBLY NEAR 80 BY WEDNESDAY. DRY
WEATHER WILL CONTINUE THROUGH THE PERIOD WITH PLENTY OF SUNSHINE.
BY THURSDAY THE NEW 12Z ECMWF LEANS A WEAK COLD FRONT INTO THE LOWER
LAKES...BUT THE 12Z GFS IS MUCH SLOWER WITH THIS FRONT KEEPING IT
WELL TO OUR WEST.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
LOCALIZED FOG ACROSS THE SOUTHERN TIER AND NIAGARA FRONTIER WILL
DISSIPATE OVER THE NEXT COUPLE OF HOURS AS SUNSHINE AND VFR
CONDITIONS TAKE HOLD ACROSS THE REGION. VFR CONDITIONS WILL THEN
PREVAIL THROUGH THE REST OF THE TAF PERIOD. THERE IS A POSSIBILITY
OF SHOWERS AND THUNDERSTORMS DEVELOPING THIS AFTERNOON WITH THE
FOCUS BEING ACROSS THE GENESEE VALLEY AND FINGER LAKES. ANY
CONVECTION THIS AFTERNOON SHOULD WEAKEN AND/OR LIFT NORTH THIS
EVENING AS THE STALLED OUT FRONTAL BOUNDARY AIDING THE DEVELOPMENT
OF THESE SHRA/TSRA LIFTS NORTH INTO CANADA AS A WARM FRONT.
THE MAIN FOCUS WILL THEN SHIFT TO THE RAPIDLY DEVELOPING LOW
PRESSURE SYSTEM THAT IS FORECAST TO TRACK ACROSS THE LOWER GREAT
LAKES FRIDAY NIGHT AND SATURDAY BRINGING WIDESPREAD HEAVY RAIN WITH
WIDESPREAD MVFR/IFR CONDITIONS AND STRONG WINDS. THE LEADING EDGE OF
THIS FRONTAL BAND IS EXPECTED TO BEGIN TO EDGE INTO THE NIAGARA
FRONTIER AND WESTERN SOUTHERN TIER AFTER 09Z SATURDAY MORNING WITH
CONDITIONS CONTINUING TO DETERIORATE THROUGH THE MORNING ON
SATURDAY...NEAR AND AFTER THE END OF THE CURRENT TAF PERIOD. IN
ADDITION...THE ARRIVAL OF A 35-40KT LOW LEVEL JET MAY POSE LLWS
ISSUES AFTER 09Z HOWEVER THIS WILL BE DEPENDENT ON HOW STRONG THE
NOCTURNAL INVERSION SETS UP TONIGHT.
OUTLOOK...
SATURDAY...MVFR/IFR IN RAIN AND SCATTERED THUNDERSTORMS.
SUNDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
MONDAY THROUGH WEDNESDAY...VFR.
&&
.MARINE...
LIGHT WINDS AND WAVES WILL PREVAIL ON THE LAKES TODAY AND THIS
EVENING AS HIGH PRESSURE SLOWLY RETREATS TOWARDS THE EAST COAST.
CONDITIONS ON THE LAKES WILL DETERIORATE FROM WEST TO EAST LATER
TONIGHT AS A RAPIDLY DEVELOPING LOW PRESSURE SYSTEM TRACKS FROM THE
MIDWEST ACROSS THE LOWER GREAT LAKES. SOUTHERLY WINDS WILL FRESHEN
AHEAD OF THIS LOW LATE FRIDAY NIGHT/EARLY SATURDAY MORNING AND WILL
TRANSITION TO STRONGER WEST/SOUTHWESTERLY WINDS LATER ON SATURDAY AS
A COLD FRONT SWEEPS ACROSS THE LAKES. A BRIEF PERIOD OF GALES MAY BE
POSSIBLE IMMEDIATELY IN THE WAKE OF THE FRONT...HOWEVER THERE IS
STILL SOME UNCERTAINTY AS TO WHERE EXACTLY THE STRONGEST WINDS WILL
LINE UP WITH RELATION TO THE LAKES.
SIGNIFICANTLY COLDER AIR WILL FILTER INTO THE REGION BEHIND THE COLD
FRONT...BRINGING AN INCREASED POTENTIAL FOR WATERSPOUTS FOR THE
LATTER HALF OF THE WEEKEND INTO THE EARLY PART OF NEXT WEEK. IN
ADDITION A PROLONGED PERIOD OF BRISK WESTERLY WINDS WILL LIKELY MEAN
AN EXTENDED PERIOD OF SMALL CRAFT ADVISORY CONDITIONS ON THE LAKES.
&&
.CLIMATE...
AN EARLY WARM SPRING AND CONTINUED WARMTH THROUGH THE SUMMER HAS
LED TO MANY DAYS THAT HAVE REACHED 80F ACROSS WESTERN AND NORTH
CENTRAL NEW YORK. BELOW IS A LIST OF THE NUMBER OF DAYS IN THE
CALENDAR YEAR THAT HAVE REACHED 80 DEGREES OR GREATER. THE 2012
TOTAL WILL INCREASE AS WE REACH ADDITIONAL 80F DAYS THROUGH THE
EARLY FALL.
BUFFALO (SINCE 1871)
1 83 1949
2 82 1959
3 77 1991
77 2012 (THROUGH THU 9/6)
5 76 1955
6 75 1947
75 1983
75 2005
9 73 2011
ROCHESTER (SINCE 1871)
1 91 1959
2 86 2007
3 83 2002
83 1973
83 1949
83 1947
7 82 2012 (THROUGH THU 9/6)
8 81 1991
9 80 2005
80 1921
...
21 75 2011
WATERTOWN (SINCE 1949)
1 75 1949
2 73 1959
3 69 2012 (THROUGH THU 9/6)
4 68 1955
5 67 1973
...
9 60 2011
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...WOOD
NEAR TERM...APFFEL/WOOD
SHORT TERM...WCH
LONG TERM...HITCHCOCK
AVIATION...WOOD
MARINE...WOOD
CLIMATE...THOMAS/JJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
130 PM EDT FRI SEP 7 2012
.SYNOPSIS...
LONG PERIOD SWELLS FROM HURRICANE LESLIE WILL IMPACT THE BEACHES
THROUGH THE WEEKEND...INCREASING THE RISK FOR STRONG AND FREQUENT RIP
CURRENTS AND LARGER THAN NORMAL BREAKERS. A WEAK RIDGE OF HIGH
PRESSURE WILL REMAIN ALONG THE COAST AS A TROUGH OF LOW PRESSURE
SLOWLY APPROACHES THE CAROLINAS FROM THE WEST TODAY. A STRONGER
FRONTAL SYSTEM WILL USHER IN FALL-LIKE WEATHER SUNDAY...WITH DRIER
AND COOLER HIGH PRESSURE BUILDING IN THROUGH NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE EXITING SHORTWAVE CLEARLY VISIBLE IN WV IMAGERY SUGGESTS THAT
DOWNWARD VERTICAL MOTION SHOULD BE IN PLACE AT THE MID LEVELS
THROUGH MOST OF THE DAY. THIS WILL ACT TO SUPPRESS ALL BUT THE MOST
ISOLATED ACTIVITY ALONG THE SEABREEZE. INLAND LOCATIONS HAVE FAIRLY
EXTENSIVE CLOUD COVER AND MAY HAVE A TOUGH TIME SEEING ANY
CONVECTION UNLESS THE CLOUDS THIN. BOTH OF THESE ARE BACKED BY THE
LATEST RUN OF THE HRRR. NO CHANGES TO THE PREVIOUS FORECAST ARE
ANTICIPATED.
AS OF 630 AM FRIDAY...NO CHANGES HAVE BEEN MADE WITH RESPECT TO
ANTICIPATED COVERAGE OF AFTERNOON SHOWERS AND THUNDERSTORMS. CURRENT
RADAR LOOPS SHOW A CLUSTER OF SHOWERS IN GEORGETOWN COUNTY AND
PERHAPS HINTS OF ADDITIONAL DEVELOPMENT UPSTREAM THE SANTEE RIVER
ACROSS WILLIAMSBURG COUNTY. 06Z MODELS WERE SLIGHTLY COOLER WITH
AFTERNOON HIGHS SO A FEW SPOTS HAVE BEEN DROPPED BY A DEGREE.
CHANGES WERE ALL MINOR. PREVIOUS DISCUSSION FROM 330 AM FOLLOWS...
A WEAK 500 MB DISTURBANCE AND SURFACE TROUGH/OUTFLOW BOUNDARY HAVE
BEEN MAINTAINING SCATTERED CONVECTION THROUGH THE EARLY MORNING
HOURS. ACTIVITY HAS BEEN MOST PREVALENT IN THE SC PEE DEE REGION
WHERE RADAR ESTIMATES UP TO 4.50 INCHES OF RAIN EXIST ACROSS
PORTIONS OF FLORENCE...MARION AND WILLIAMSBURG COUNTIES.
THERMODYNAMICALLY THIS CONVECTION IS ELEVATED...ROOTED IN A LAYER
4000-7000 FT ABOVE THE GROUND. AS THE UPPER DISTURBANCES WEAKENS AND
PRESSES OFFSHORE IN THE NEXT COUPLE OF HOURS THE CONVECTION SHOULD
WEAKEN AS WELL. THE 04Z HRRR DID NOT INITIALIZE WELL...BUT EARLIER
RUNS (PARTICULARLY THE 01Z RUN) MODEL THE CURRENTLY OBSERVED
PATTERNS ON RADAR WELL.
LOW STRATUS CLOUDS ARE FILLING IN NORTH OF THE RAIN AREA AND MAY
SPREAD DOWN AS FAR SOUTH AS FLORENCE...MARION...WHITEVILLE AND
WILMINGTON BY DAYBREAK. AFTER PROVIDING A GLOOMY SUNRISE THESE
CLOUDS SHOULD BURN OFF BY 10:00 AM WITH AN EXPANSIVE CUMULUS FIELD
DEVELOPING IN ITS PLACE. TRIGGERS FOR AFTERNOON CONVECTION SHOULD
INCLUDE A WELL-DEFINED SEABREEZE...THE REMNANT OUTFLOW BOUNDARY FROM
THE EARLY MORNING CONVECTION ACROSS SOUTH CAROLINA...AND A
DIFFERENTIAL HEATING BOUNDARY AROUND THE EDGE OF THE MORNING LOW
STRATUS DECK. DESPITE NO SUPPORT FROM THE UPPER LEVELS AND A
FORECAST STORM CELL MOTION OF LESS THAN 5 MPH...I`M STILL INCLUDING
20 POPS INLAND AND 30 POPS NEAR THE COAST FOR THIS AFTERNOON GIVEN
ALL THE SURFACE BOUNDARIES AND WIDESPREAD 1500 J/KG SURFACE-BASED
CAPE EXPECTED.
ANY LINGERING CONVECTION SHOULD DIE AWAY QUICKLY THIS EVENING AS THE
BOUNDARY LAYER COOLS. THE ATMOSPHERE WILL BEGIN TO RESPOND TO AN
APPROACHING UPPER LEVEL TROUGH THAT WILL DRIVE A STRONG COLD FRONT
THROUGH THE CAROLINAS THIS WEEKEND. DEEP-LAYER FLOW THAT IS
ESSENTIALLY LIGHT AND VARIABLE THIS AFTERNOON WILL TURN SOUTHWEST
AND STEADILY INCREASE THROUGH THE NIGHT. SURFACE WINDS WILL NOT
INCREASE APPRECIABLY GIVEN THE STABLE LOW-LEVEL THERMAL PROFILES AT
NIGHT...BUT WINDS 1000 FT AGL AND HIGHER WILL PICK UP SPEED AFTER
MIDNIGHT.
HIGHS TODAY SHOULD REACH 90 OR SO INLAND...WITH UPPER 80S NEAR THE
COAST AND MID 80S ON THE BEACHES. LOWS TONIGHT WILL FALL INTO THE
LOWER TO MID 70S.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM FRIDAY...STRONG COLD FRONT WILL APPROACH THE AREA
SATURDAY MOVING THROUGH BY SUNDAY. LOCAL AREA WILL BE IN WARM
SECTOR ON SAT WITH DEEP LAYER MOISTURE MAKING ITS WAY IN A SW FLOW
LATER IN THE DAY AS MOISTURE POOLS AHEAD OF FRONT. GFS ACTUAL
SHOWS SOME DRIER AIR IN PLACE IN THE MID LEVELS INITIALLY THROUGH
THE AFTERNOON AND THEN PCP WATER VALUES SHOOT UP OVER 2 INCHES
THROUGH SAT EVENING. EXPECT BEST LIFT AND MOISTURE THROUGH THE
LATE EVENING AND OVERNIGHT AS MID TO UPPER TROUGH PUSHES COLD FRONT
THROUGH. POTENTIAL FOR STRONG TO SEVERE STORMS ESPECIALLY JUST
AHEAD OF FRONT. THE FRONT WILL MAKE IT THROUGH AFTER THE BEST
HEATING OF THE DAY AND THIS MAY WORK IN OUR FAVOR LIMITING MORE
WIDESPREAD STORMS.
THE SFC FRONT SHOULD MAKE IT OFF SHORE BY SUN MORNING BUT
WINDS IN THE LOW TO MID LEVELS WILL TAKE A LITTLE WHILE LONGER TO
VEER AROUND. PCP WATER VALUES WILL DROP OUT THROUGH SUNDAY DOWN
LESS THAN 1.5 INCHES BY SUN AFTN AND DROPPING EVEN FURTHER TO LESS
THAN AN INCH BY END OF THE PERIOD.
OVERALL EXPECT MORE LOCALIZED CONVECTION THROUGH SAT AFTN WITH
MORE WIDESPREAD ACTIVITY WITH APPROACH OF FRONT LATE SAT INTO
EARLY SUNDAY. THEN CLEARING THROUGH SUNDAY BEHIND FRONT AS PLENTY
OF DRY AIR MAKES IT WAY IN.
SAT WILL BE THE LAST DAY OF VERY WARM TEMPS AS 850 TEMPS REMAIN UP
NEAR 18 C BUT AS COOLER AIR ADVECTS IN ON SUNDAY...850 TEMPS WILL
FALL THROUGH THE DAY REACHING DOWN TO 10 C BY MON MORNING. MAX
TEMPS ON SAT WILL BE UP AROUND 90 OR SO WHILE SUNDAY THE TEMPS
WILL BE BETWEEN 80 AND 85 MOST PLACES WHILE DEWPOINT TEMPS DROP
ABOUT 10 DEGREES DOWN TO 60.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 300 AM FRIDAY...FALL LIKE WEATHER WILL EXIST THROUGH MUCH OF
NEXT WEEK AS COOL AND DRY HIGH PRESSURE BUILDS DOWN OVER THE
SOUTHEAST. BRIGHT SEPTEMBER SUN WILL PRODUCE MAX TEMPS BETWEEN 80
AND 85 MOST PLACES BUT THE VERY DRY AIR MASS WILL PRODUCE SOME
LARGE DIURNAL SWINGS. WITH DEWPOINT TEMPS DOWN INTO THE 50S
THROUGH AT LEAST WED AND WINDS DROPPING OFF EACH NIGHT...EXPECT
MORE IDEAL RADIATIONAL COOLING LEADING TO OVERNIGHT LOWS AROUND 60
WITH UPPER 50S INLAND. ACTUALLY TEMPS WILL BE CLOSE TO NORMAL AND
WILL CREEP UPWARD THROUGH MID WEEK AS H5 HEIGHTS RISE BACK UP WITH
RIDGE BUILDING IN THE SOUTHEAST. BY WED MOISTURE INCREASES ENOUGH
IN THE LOW LEVELS AS WINDS SHIFT AROUND TO THE NE TO PRODUCE SOME
CU AROUND. OVERALL EXPECT SUNNY AND DRY WEATHER THROUGH THE WEEK.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 18Z...STILL LOOKING FOR ISOLATED CONVECTION THIS
AFTERNOON...MAINLY ALONG THE COAST. BEST CHANCE WILL BE AROUND MAX
HEATING...WITH MOST OF THE ACTIVITY ENDING BY 22Z. WINDS WILL BE
VARIABLE THIS MORNING WITH THE LIGHT GRADIENT...BECOMING
PREDOMINATELY EAST SOUTHEAST WITH THE RESULTANT THIS AFTERNOON.
TONIGHT...THINK WE COULD SEE SOME STRATUS...PROBABLY THE INLAND
TERMINALS. SATURDAY...FRONTAL BOUNDARY WILL APPROACH FROM THE WEST.
NO EFFECTS FOR THE TAF PERIOD...SAVE AN INCREASING SOUTHWEST WIND.
EXTENDED OUTLOOK...SCATTERED SHRA/TSRA THROUGH SUNDAY...WITH A CHANCE
OF EARLY MORNING LIFR/IFR CONDITIONS IN BR INLAND...AND MVFR AT THE
COAST. VFR MONDAY THROUGH WEDNESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM FRIDAY...NO CHANGES NEEDED TO THE MARINE FORECAST.
PREVIOUS DISCUSSION FROM 330 AM FOLLOWS...
A WEAK UPPER LEVEL DISTURBANCE AND SURFACE TROUGH ALONG THE CAROLINA
COAST IS RESPONSIBLE FOR SEVERAL WAVES OF SHOWERS AND THUNDERSTORMS
AFFECTING THE NC OFFSHORE WATER THIS MORNING. SCATTERED SHOWERS AND
STORMS SHOULD DIMINISH IN COVERAGE THROUGH THE EARLY MORNING HOURS
AS THIS DISTURBANCE PUSHES OFFSHORE AND WEAKENS FURTHER.
GENERALLY OFFSHORE WINDS EARLY THIS MORNING WILL TURN LIGHT AND
VARIABLE LATER THIS MORNING...AND THEN SOUTHERLY DRIVEN PRIMARILY BY
THE SEABREEZE THIS AFTERNOON. A STRONG COLD FRONT APPROACHING FROM
THE WEST WILL CREATE SLOWLY INCREASING SOUTHWEST WINDS TONIGHT.
SWELL FROM HURRICANE LESLIE HAS SHORTENED TO AROUND 10 SECONDS IN
PERIOD AND SHOULD CONTINUE THROUGH THE WEEKEND. ADDITIONAL SHORT
PERIOD WIND WAVES WILL ADD VERY LITTLE EXTRA TO THE TOTAL SEA
STATE...AND WE`RE EXPECTING 2-4 FT ACROSS THE SOUTH CAROLINA COASTAL
WATERS...AND 3-4 FT FOR THE NC COASTAL WATERS.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM FRIDAY...SOUTHWEST FLOW WILL INCREASE THROUGH SATURDAY
AHEAD OF APPROACHING COLD FRONT. SOUTHWEST WINDS UP AROUND 15 KTS
WILL VEER AROUND BECOMING OFF SHORE THROUGH SUNDAY MORNING AS COLD
FRONT MOVES THROUGH. THESE SOUTHWEST WINDS WILL COMBINE WITH
CONTINUED LONG PERIOD E-SE SWELLS TO PRODUCE SEAS IN THE 3 TO 5 FT
RANGE MOST PLACES THROUGH SATURDAY. THERE WILL BE SOME 6 FTERS IN
OUTER WATERS.
AS COLD FRONT MOVES FURTHER OFF SHORE THROUGH SUNDAY...WINDS WILL
VEER AROUND TO THE NORTH AROUND 10 TO 15 KTS AS HIGH PRESSURE
BUILDS IN FROM THE N-NW.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 300 AM FRIDAY...NORTHERLY WINDS WILL CONTINUE TO MIX WITH
LONGER PERIOD SWELLS FROM LESLIE TO PRODUCE SEAS IN THE 2 TO 4 FT
RANGE MOST WATERS. THE COOL NIGHTS WILL KEEP A WELL MIXED
ATMOSPHERE AS COOL AIR RIDES OVER THE WARM WATERS. THIS COULD
PRODUCE NORTHERLY WINDS UP TO 20 KTS OVERNIGHT. EXPECT SEAS CLOSER
TO 5 FT IN OUTER WATERS AND MAY SEE SEAS UP NEAR OR SLIGHTLY ABOVE
SCA EARLY MON IN NORTHERLY SURGE BEHIND FRONT. THE WINDS WILL
GRADUALLY SHIFT AROUND BECOMING NE TO E AS HIGH PRESSURE BUILDS
SOUTH AND EAST THROUGH MID WEEK.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...MBB
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1030 AM EDT FRI SEP 7 2012
.SYNOPSIS...
LONG PERIOD SWELLS FROM HURRICANE LESLIE WILL IMPACT THE BEACHES
THROUGH THE WEEKEND...INCREASING THE RISK FOR STRONG AND FREQUENT RIP
CURRENTS AND LARGER THAN NORMAL BREAKERS. A WEAK RIDGE OF HIGH
PRESSURE WILL REMAIN ALONG THE COAST AS A TROUGH OF LOW PRESSURE
SLOWLY APPROACHES THE CAROLINAS FROM THE WEST TODAY. A STRONGER
FRONTAL SYSTEM WILL USHER IN FALL-LIKE WEATHER SUNDAY...WITH DRIER
AND COOLER HIGH PRESSURE BUILDING IN THROUGH NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE EXITING SHORTWAVE CLEARLY VISIBLE IN WV IMAGERY SUGGESTS THAT
DOWNWARD VERTICAL MOTION SHOULD BE IN PLACE AT THE MID LEVELS
THROUGH MOST OF THE DAY. THIS WILL ACT TO SUPPRESS ALL BUT THE MOST
ISOLATED ACTIVITY ALONG THE SEABREEZE. INLAND LOCATIONS HAVE FAIRLY
EXTENSIVE CLOUD COVER AND MAY HAVE A TOUGH TIME SEEING ANY
CONVECTION UNLESS THE CLOUDS THIN. BOTH OF THESE ARE BACKED BY THE
LATEST RUN OF THE HRRR. NO CHANGES TO THE PREVIOUS FORECAST ARE
ANTICIPATED.
AS OF 630 AM FRIDAY...NO CHANGES HAVE BEEN MADE WITH RESPECT TO
ANTICIPATED COVERAGE OF AFTERNOON SHOWERS AND THUNDERSTORMS. CURRENT
RADAR LOOPS SHOW A CLUSTER OF SHOWERS IN GEORGETOWN COUNTY AND
PERHAPS HINTS OF ADDITIONAL DEVELOPMENT UPSTREAM THE SANTEE RIVER
ACROSS WILLIAMSBURG COUNTY. 06Z MODELS WERE SLIGHTLY COOLER WITH
AFTERNOON HIGHS SO A FEW SPOTS HAVE BEEN DROPPED BY A DEGREE.
CHANGES WERE ALL MINOR. PREVIOUS DISCUSSION FROM 330 AM FOLLOWS...
A WEAK 500 MB DISTURBANCE AND SURFACE TROUGH/OUTFLOW BOUNDARY HAVE
BEEN MAINTAINING SCATTERED CONVECTION THROUGH THE EARLY MORNING
HOURS. ACTIVITY HAS BEEN MOST PREVALENT IN THE SC PEE DEE REGION
WHERE RADAR ESTIMATES UP TO 4.50 INCHES OF RAIN EXIST ACROSS
PORTIONS OF FLORENCE...MARION AND WILLIAMSBURG COUNTIES.
THERMODYNAMICALLY THIS CONVECTION IS ELEVATED...ROOTED IN A LAYER
4000-7000 FT ABOVE THE GROUND. AS THE UPPER DISTURBANCES WEAKENS AND
PRESSES OFFSHORE IN THE NEXT COUPLE OF HOURS THE CONVECTION SHOULD
WEAKEN AS WELL. THE 04Z HRRR DID NOT INITIALIZE WELL...BUT EARLIER
RUNS (PARTICULARLY THE 01Z RUN) MODEL THE CURRENTLY OBSERVED
PATTERNS ON RADAR WELL.
LOW STRATUS CLOUDS ARE FILLING IN NORTH OF THE RAIN AREA AND MAY
SPREAD DOWN AS FAR SOUTH AS FLORENCE...MARION...WHITEVILLE AND
WILMINGTON BY DAYBREAK. AFTER PROVIDING A GLOOMY SUNRISE THESE
CLOUDS SHOULD BURN OFF BY 10:00 AM WITH AN EXPANSIVE CUMULUS FIELD
DEVELOPING IN ITS PLACE. TRIGGERS FOR AFTERNOON CONVECTION SHOULD
INCLUDE A WELL-DEFINED SEABREEZE...THE REMNANT OUTFLOW BOUNDARY FROM
THE EARLY MORNING CONVECTION ACROSS SOUTH CAROLINA...AND A
DIFFERENTIAL HEATING BOUNDARY AROUND THE EDGE OF THE MORNING LOW
STRATUS DECK. DESPITE NO SUPPORT FROM THE UPPER LEVELS AND A
FORECAST STORM CELL MOTION OF LESS THAN 5 MPH...I`M STILL INCLUDING
20 POPS INLAND AND 30 POPS NEAR THE COAST FOR THIS AFTERNOON GIVEN
ALL THE SURFACE BOUNDARIES AND WIDESPREAD 1500 J/KG SURFACE-BASED
CAPE EXPECTED.
ANY LINGERING CONVECTION SHOULD DIE AWAY QUICKLY THIS EVENING AS THE
BOUNDARY LAYER COOLS. THE ATMOSPHERE WILL BEGIN TO RESPOND TO AN
APPROACHING UPPER LEVEL TROUGH THAT WILL DRIVE A STRONG COLD FRONT
THROUGH THE CAROLINAS THIS WEEKEND. DEEP-LAYER FLOW THAT IS
ESSENTIALLY LIGHT AND VARIABLE THIS AFTERNOON WILL TURN SOUTHWEST
AND STEADILY INCREASE THROUGH THE NIGHT. SURFACE WINDS WILL NOT
INCREASE APPRECIABLY GIVEN THE STABLE LOW-LEVEL THERMAL PROFILES AT
NIGHT...BUT WINDS 1000 FT AGL AND HIGHER WILL PICK UP SPEED AFTER
MIDNIGHT.
HIGHS TODAY SHOULD REACH 90 OR SO INLAND...WITH UPPER 80S NEAR THE
COAST AND MID 80S ON THE BEACHES. LOWS TONIGHT WILL FALL INTO THE
LOWER TO MID 70S.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM FRIDAY...STRONG COLD FRONT WILL APPROACH THE AREA
SATURDAY MOVING THROUGH BY SUNDAY. LOCAL AREA WILL BE IN WARM
SECTOR ON SAT WITH DEEP LAYER MOISTURE MAKING ITS WAY IN A SW FLOW
LATER IN THE DAY AS MOISTURE POOLS AHEAD OF FRONT. GFS ACTUAL
SHOWS SOME DRIER AIR IN PLACE IN THE MID LEVELS INITIALLY THROUGH
THE AFTERNOON AND THEN PCP WATER VALUES SHOOT UP OVER 2 INCHES
THROUGH SAT EVENING. EXPECT BEST LIFT AND MOISTURE THROUGH THE
LATE EVENING AND OVERNIGHT AS MID TO UPPER TROUGH PUSHES COLD FRONT
THROUGH. POTENTIAL FOR STRONG TO SEVERE STORMS ESPECIALLY JUST
AHEAD OF FRONT. THE FRONT WILL MAKE IT THROUGH AFTER THE BEST
HEATING OF THE DAY AND THIS MAY WORK IN OUR FAVOR LIMITING MORE
WIDESPREAD STORMS.
THE SFC FRONT SHOULD MAKE IT OFF SHORE BY SUN MORNING BUT
WINDS IN THE LOW TO MID LEVELS WILL TAKE A LITTLE WHILE LONGER TO
VEER AROUND. PCP WATER VALUES WILL DROP OUT THROUGH SUNDAY DOWN
LESS THAN 1.5 INCHES BY SUN AFTN AND DROPPING EVEN FURTHER TO LESS
THAN AN INCH BY END OF THE PERIOD.
OVERALL EXPECT MORE LOCALIZED CONVECTION THROUGH SAT AFTN WITH
MORE WIDESPREAD ACTIVITY WITH APPROACH OF FRONT LATE SAT INTO
EARLY SUNDAY. THEN CLEARING THROUGH SUNDAY BEHIND FRONT AS PLENTY
OF DRY AIR MAKES IT WAY IN.
SAT WILL BE THE LAST DAY OF VERY WARM TEMPS AS 850 TEMPS REMAIN UP
NEAR 18 C BUT AS COOLER AIR ADVECTS IN ON SUNDAY...850 TEMPS WILL
FALL THROUGH THE DAY REACHING DOWN TO 10 C BY MON MORNING. MAX
TEMPS ON SAT WILL BE UP AROUND 90 OR SO WHILE SUNDAY THE TEMPS
WILL BE BETWEEN 80 AND 85 MOST PLACES WHILE DEWPOINT TEMPS DROP
ABOUT 10 DEGREES DOWN TO 60.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 300 AM FRIDAY...FALL LIKE WEATHER WILL EXIST THROUGH MUCH OF
NEXT WEEK AS COOL AND DRY HIGH PRESSURE BUILDS DOWN OVER THE
SOUTHEAST. BRIGHT SEPTEMBER SUN WILL PRODUCE MAX TEMPS BETWEEN 80
AND 85 MOST PLACES BUT THE VERY DRY AIR MASS WILL PRODUCE SOME
LARGE DIURNAL SWINGS. WITH DEWPOINT TEMPS DOWN INTO THE 50S
THROUGH AT LEAST WED AND WINDS DROPPING OFF EACH NIGHT...EXPECT
MORE IDEAL RADIATIONAL COOLING LEADING TO OVERNIGHT LOWS AROUND 60
WITH UPPER 50S INLAND. ACTUALLY TEMPS WILL BE CLOSE TO NORMAL AND
WILL CREEP UPWARD THROUGH MID WEEK AS H5 HEIGHTS RISE BACK UP WITH
RIDGE BUILDING IN THE SOUTHEAST. BY WED MOISTURE INCREASES ENOUGH
IN THE LOW LEVELS AS WINDS SHIFT AROUND TO THE NE TO PRODUCE SOME
CU AROUND. OVERALL EXPECT SUNNY AND DRY WEATHER THROUGH THE WEEK.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AS OF 12Z...THE CONVECTION HAS NOW EXITED THE COAST...ALONG WITH THE
DEEP MOISTURE. ORIGINALLY THOUGHT WE WOULD SEE BOUTS OF STRATUS FOR
THE FIRST COUPLE OF HOURS THIS MORNING...HOWEVER IT SEEMS MOST OF IT
HAS NOW DISSIPATED. MODELS INDICATE THERE WILL BE ENOUGH MOISTURE
ALONG THE IMMEDIATE COAST TO KICK OFF SCATTERED CONVECTION. BEST
CHANCE WILL BE AROUND MAX HEATING...WITH MOST OF THE ACTIVITY ENDING
BY 22Z. WINDS WILL BE VARIABLE THIS MORNING WITH THE LIGHT
GRADIENT...BECOMING PREDOMINATELY EAST SOUTHEAST WITH THE RESULTANT
THIS AFTERNOON.
EXTENDED OUTLOOK...SCATTERED SHRA/TSRA THROUGH SUNDAY...WITH A CHANCE
OF EARLY MORNING LIFR/IFR CONDITIONS IN BR INLAND...AND MVFR AT THE
COAST. VFR MONDAY AND TUESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM FRIDAY...NO CHANGES NEEDED TO THE MARINE FORECAST.
PREVIOUS DISCUSSION FROM 330 AM FOLLOWS...
A WEAK UPPER LEVEL DISTURBANCE AND SURFACE TROUGH ALONG THE CAROLINA
COAST IS RESPONSIBLE FOR SEVERAL WAVES OF SHOWERS AND THUNDERSTORMS
AFFECTING THE NC OFFSHORE WATER THIS MORNING. SCATTERED SHOWERS AND
STORMS SHOULD DIMINISH IN COVERAGE THROUGH THE EARLY MORNING HOURS
AS THIS DISTURBANCE PUSHES OFFSHORE AND WEAKENS FURTHER.
GENERALLY OFFSHORE WINDS EARLY THIS MORNING WILL TURN LIGHT AND
VARIABLE LATER THIS MORNING...AND THEN SOUTHERLY DRIVEN PRIMARILY BY
THE SEABREEZE THIS AFTERNOON. A STRONG COLD FRONT APPROACHING FROM
THE WEST WILL CREATE SLOWLY INCREASING SOUTHWEST WINDS TONIGHT.
SWELL FROM HURRICANE LESLIE HAS SHORTENED TO AROUND 10 SECONDS IN
PERIOD AND SHOULD CONTINUE THROUGH THE WEEKEND. ADDITIONAL SHORT
PERIOD WIND WAVES WILL ADD VERY LITTLE EXTRA TO THE TOTAL SEA
STATE...AND WE`RE EXPECTING 2-4 FT ACROSS THE SOUTH CAROLINA COASTAL
WATERS...AND 3-4 FT FOR THE NC COASTAL WATERS.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM FRIDAY...SOUTHWEST FLOW WILL INCREASE THROUGH SATURDAY
AHEAD OF APPROACHING COLD FRONT. SOUTHWEST WINDS UP AROUND 15 KTS
WILL VEER AROUND BECOMING OFF SHORE THROUGH SUNDAY MORNING AS COLD
FRONT MOVES THROUGH. THESE SOUTHWEST WINDS WILL COMBINE WITH
CONTINUED LONG PERIOD E-SE SWELLS TO PRODUCE SEAS IN THE 3 TO 5 FT
RANGE MOST PLACES THROUGH SATURDAY. THERE WILL BE SOME 6 FTERS IN
OUTER WATERS.
AS COLD FRONT MOVES FURTHER OFF SHORE THROUGH SUNDAY...WINDS WILL
VEER AROUND TO THE NORTH AROUND 10 TO 15 KTS AS HIGH PRESSURE
BUILDS IN FROM THE N-NW.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 300 AM FRIDAY...NORTHERLY WINDS WILL CONTINUE TO MIX WITH
LONGER PERIOD SWELLS FROM LESLIE TO PRODUCE SEAS IN THE 2 TO 4 FT
RANGE MOST WATERS. THE COOL NIGHTS WILL KEEP A WELL MIXED
ATMOSPHERE AS COOL AIR RIDES OVER THE WARM WATERS. THIS COULD
PRODUCE NORTHERLY WINDS UP TO 20 KTS OVERNIGHT. EXPECT SEAS CLOSER
TO 5 FT IN OUTER WATERS AND MAY SEE SEAS UP NEAR OR SLIGHTLY ABOVE
SCA EARLY MON IN NORTHERLY SURGE BEHIND FRONT. THE WINDS WILL
GRADUALLY SHIFT AROUND BECOMING NE TO E AS HIGH PRESSURE BUILDS
SOUTH AND EAST THROUGH MID WEEK.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...MBB
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...43
AREA FORECAST DISCUSSION
NWS RALEIGH NC
731 AM EDT FRI SEP 7 2012
.SYNOPSIS...
A WEAK SURFACE TROUGH WILL STALL OVER THE EASTERN CAROLINAS TODAY. A
DEEPENING LOW PRESSURE SYSTEM OVER THE GREAT LAKES WILL PUSH A
STRONG COLD FRONT THROUGH THE CAROLINAS SATURDAY AFTERNOON AND
EVENING. COOLER AND DRIER CONDITIONS WILL PREVAIL IN THE WAKE OF THE
FRONT SUNDAY THROUGH EARLY NEXT WEEK AS HIGH PRESSURE BUILDS INTO
THE REGION.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 330 AM FRIDAY...
OVERVIEW:
AN H5 SHORTWAVE CENTERED NEAR THE HWY 1 CORRIDOR AT 06Z THIS MORNING
IS EXPECTED TO TRACK SLOWLY EAST TOWARD THE CAROLINA COAST THIS
AFTERNOON BEFORE FURTHER WEAKENING AND SHIFTING OFFSHORE THIS
EVENING/TONIGHT. A SFC-H85 TROUGH ATTENDANT THE SHORTWAVE IS PROGGED
TO STALL OUT OVER THE COASTAL PLAIN TODAY...THEN DISSIPATE TONIGHT
AS HEIGHT FALLS OVERSPREAD THE AREA FROM WEST-EAST IN ADVANCE OF AN
AMPLIFYING UPPER LEVEL TROUGH AND ASSOCIATED SURFACE COLD FRONT
PROGRESSING INTO THE OH VALLEY.
PRECIPITATION CHANCES:
MOISTURE THROUGHOUT THE COLUMN WILL VARY WIDELY ACROSS THE AREA
TODAY...BETWEEN A DRY AIRMASS (PWAT VALUES ~1.00") OVER THE
MOUNTAINS AND A VERY MOIST AIRMASS (PWAT VALUES ~2.00") OVER THE
COASTAL CAROLINAS WHERE THE AFOREMENTIONED SFC-H85 TROUGH IS PROGGED
TO STALL OUT. THE LATEST GFS/RAP MODEL GUIDANCE INDICATES THE DRIER
AIRMASS TO THE NORTH AND WEST ADVECTING INTO CENTRAL NC THROUGHOUT
THE MORNING...WITH PWAT VALUES FALLING TO 1.00-1.25" OVER THE BULK
OF THE AREA...EXCEPT THE SOUTHEAST COASTAL PLAIN WHERE PWAT VALUES
MAY LINGER NEAR ~1.75". THE LATEST 00Z NAM APPEARS TO BE AN
OUTLIER...INDICATING DEEPER MOISTURE LINGERING MUCH FURTHER WEST (TO
THE TRIANGLE/HWY 1 CORRIDOR) THAN EITHER THE 00Z GFS OR 06Z RAP.
GIVEN THAT THE GFS HAS SUPPORT FROM THE MOST RECENT RAP MODEL RUN...
THE NAM WILL BE DISREGARD AT THIS TIME. ANTICIPATE THAT INSTABILITY
WILL GENERALLY BE CONFINED TO AREAS SOUTH AND EAST OF THE TRIANGLE
DURING PEAK HEATING...WITH MLCAPE VALUES RANGING FROM 500-1500 J/KG
IN THE SOUTHEAST COASTAL PLAIN...PRIMARILY IN CUMBERLAND/SAMPSON/
WAYNE COUNTIES. SOME UNCERTAINTY IS PRESENT...AND THE INSTABILITY
AXIS COULD BE SLIGHTLY FURTHER TO THE EAST OR WEST...DEPENDING ON
THE LOCATION OF THE SFC-H85 TROUGH. FORCING FOR ASCENT TODAY WILL
PRIMARILY BE ASSOCIATED WITH LOW-LEVEL CONVERGENCE IN VICINITY OF
THE SEABREEZE AND THE SFC-H85 TROUGH OVER THE COASTAL CAROLINAS.
SHORTWAVE ENERGY PROGRESSING INTO ILLINOIS AT 06Z WILL PROGRESS EAST
THROUGH THE MID-ATLANTIC THIS AFTERNOON...RESULTING IN WEAK DPVA
OVER NORTHERN PORTIONS OF THE STATE. WITH THE ABOVE IN MIND...WILL
INDICATE A 20-30% CHANCE OF SHOWERS/STORMS IN THE SOUTHEAST COASTAL
PLAIN CLOSER TO THE BEST MOISTURE/INSTABILITY AND LOW-LEVEL FORCING
DURING PEAK HEATING. ANTICIPATE THAT THE DRIER /MORE STABLE/ AIRMASS
IN PLACE OVER NORTHERN PORTIONS OF THE AREA WILL PRECLUDE A CHANCE
FOR CONVECTION WITH THE AFOREMENTIONED SHORTWAVE ENERGY. WILL KEEP
THE FORECAST DRY OVERNIGHT.
TEMPERATURES:
GIVEN LESS CLOUD COVER AND 1000-850 MB THICKNESSES SIMILAR TO
PREVIOUS DAYS...EXPECT HIGHS IN THE UPPER 80S TO 90-91F. LOWS
TONIGHT IN THE UPPER 60S TO LOWER 70S...WARMEST WHERE A LIGHT
SOUTHERLY BREEZE IS PRESENT AS THE MSLP GRADIENT BEGINS TO TIGHTEN
FROM THE WEST PRIOR TO SUNRISE.
HAZARDOUS WEATHER:
CONVECTION ALLOWING MODELS DEVELOP ISOLD CONVECTION OVER THE FAR
SOUTHEAST COASTAL PLAIN THIS AFTERNOON...IN ASSOC/W THE LINGERING
SFC-H85 TROUGH AND/OR THE SEABREEZE. DEEP-LAYER SHEAR WILL BE
NEGLIGIBLE TODAY (< 15 KT IN SOUTHEAST NC)...AND DESTABILIZATION IS
EXPECTED TO YIELD RELATIVELY MARGINAL INSTABILITY WITH MLCAPE VALUES
IN THE 500-1500 J/KG RANGE...SO ANY CONVECTION THAT DEVELOPS WILL BE
UNORGANIZED AND SHORT-LIVED. HOWEVER...THE ADVECTION OF A DRIER
MID-LEVEL AIRMASS INTO THE AREA WILL RESULT IN A MARKED INCREASE IN
DCAPE THIS AFTERNOON...EVEN IN THE SOUTHEAST COASTAL PLAIN...WHERE
VIRTUALLY ALL MODEL GUIDANCE INDICATE VALUES IN THE 1000-1500 J/KG
RANGE. WITH THIS IN MIND...AN ISOLD UPDRAFT INTERACTING WITH OR
ENHANCED BY OUTFLOW IN THE PRESENCE OF RELATIVELY HIGH DCAPE COULD
YIELD A BRIEF/ISOLD INSTANCE OF DAMAGING WIND...PRIMARILY IN
CUMBERLAND/SAMPSON/WAYNE COUNTIES...THOUGH THE PROBABILITY IS TOO
LOW TO MENTION IN THE HAZARDOUS WEATHER OUTLOOK. -VINCENT
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 303 AM FRIDAY...
...SLIGHT CHANCE OF SEVERE THUNDERSTORMS SATURDAY AFTERNOON AND
EARLY EVENING...
THE BIG PATTERN CHANGE THAT HAS BEEN ADVERTISED FOR DAYS WILL START
WITH A BANG SATURDAY AFTERNOON. A POSITIVELY TILTED MID-UPPER TROUGH
IS FORECAST TO AMPLIFY AS IT DIVES SE ACROSS THE CENTRAL
APPALACHIANS AND MID-ATLANTIC STATES SATURDAY AFTERNOON. THE
ASSOCIATED COLD FRONT WILL PUSH INTO THE REGION DURING PEAK HEATING.
THE THE MOST FAVORABLE WINDS ALOFT FOR ORGANIZED SEVERE STORMS MAY
REMAIN JUST TO OUR NORTH. HOWEVER... STRONG SURFACE HEATING IS
EXPECTED TO DESTABILIZE THE BOUNDARY LAYER BY EARLY AFTERNOON OUT
AHEAD OF A PRE-FRONTAL TROUGH/REMNANT CONVECTIVE OUTFLOW BOUNDARY.
THIS BOUNDARY SHOULD BEGIN TO ARRIVE DURING PEAK HEATING FOR MUCH OF
CENTRAL NORTH CAROLINA. WITH STRONG HEATING... TEMPERATURES SHOULD
REACH AROUND 90 BY EARLY AFTERNOON THROUGHOUT MOST OF THE REGION.
THIS WILL COMBINE WITH DEW POINTS FORECAST TO BE IN THE LOWER 70S TO
PRODUCE FAVORABLE PARAMETERS FOR MULTICELL STORM CLUSTERS. A FEW
OF THESE STORMS MAY BECOME SEVERE WITH THE MAIN THREAT BEING
DAMAGING WET DOWNBURSTS. THE MULTICELL CLUSTERS MAY EVOLVE INTO A
LINE BY LATE AFTERNOON AGAIN FAVORING ISOLATED DAMAGING WIND GUSTS
ALONG LEWP/BOWING SEGMENTS. THERE MAY BE A FINAL LINE OF CONVECTION
WITH THE MAIN COLD FRONT LATER IN THE DAY OR EVENING. REGARDLESS...
SATURDAY AFTERNOON AND EVENING IS EXPECTED TO BE ACTIVE ONCE AGAIN.
IN ADDITION TO THE SLIGHT CHANCE OF SEVERE STORMS... FREQUENT CG
LIGHTNING AND LOCALLY HEAVY RAIN IS AGAIN EXPECTED WITH THE STORMS.
EARLY MORNING STRATUS WILL GIVE WAY TO PARTLY SUNNY SKIES. WE WILL
CARRY LIKELY POP FOR SHOWERS AND THUNDERSTORMS IN THE AFTERNOON AND
EVENING. HIGHS 90-93 EXCEPT UPPER 80S NW.
THE STORMS WILL GRADUALLY END SATURDAY EVENING NW... AND ELSEWHERE
OVERNIGHT WITH THE ACTUAL COLD FRONTAL PASSAGE. GOOD DRY/COOL AIR
ADVECTION WILL ARRIVE MAINLY BETWEEN 06Z-12Z. THIS LATE CAA ARRIVAL
COMBINED WITH LINGER CLOUDS SHOULD KEEP LOWS MILD AND LIKELY ABOVE
GUIDANCE. WE WILL CARRY 60-65 MOST AREAS.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 303 AM FRIDAY...
A LONG AWAITED BREATHER FROM ALL THE VERY WARM/HUMID/THUNDERY
WEATHER WILL BEGIN SUNDAY. A REFRESHING BREEZE WILL COMBINE WITH
AMPLE SUNSHINE TO BRING A SPRING-LIKE FEEL. HIGHS OF 78-83 EXPECTED
(WITH DEW POINTS IN THE 40S NW AND LOWER 50S SE). A NORTHERLY BREEZE
AT 10-15 MPH WILL MAKE IT FEEL APRIL-FRESH AT TIMES.
MONDAY THROUGH THURSDAY...
EXPECT DRY AND SEASONABLY COOL CONDITIONS MONDAY AND TUESDAY... WITH
MODERATING DAYTIME TEMPS WED AND THUR. MOSTLY CLEAR/MOSTLY SUNNY
WITH LOWS IN THE 50S EACH DAY. HIGHS 75 TO 80 MON-TUE... WARMING
INTO THE LOWER TO MID 80S BY THURSDAY.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AS OF 730 AM FRIDAY...
24-HR TAF PERIOD:
MVFR TO VLIFR CONDITIONS ARE PRESENT OVER CENTRAL NC AS OF 11Z. FOG
AND LOW CEILINGS ARE EXPECTED TO LIFT AND SCATTER TO VFR BETWEEN
12-15Z AT INT/GSO/RDU. CONDITIONS SHOULD BE SLOWER TO IMPROVE AT THE
FAY/RWI TERMINALS WHERE MOISTURE IS DEEPER AND MVFR CEILINGS MAY
PERSIST THROUGH ~18Z...ESPECIALLY AT FAY. ISOLATED SHOWERS AND
STORMS WILL BE POSSIBLE DURING THE AFTERNOON...THOUGH CHANCES WILL
MOST LIKELY BE LIMITED TO THE FAY TERMINAL. OTHERWISE...EXPECT VFR
CONDITIONS TO PREVAIL THIS AFTERNOON INTO TONIGHT. LOW-LEVEL
SOUTHERLY FLOW WILL STRENGTHEN PRIOR TO SUNRISE SATURDAY IN ADVANCE
OF AN APPROACHING COLD FRONT...AND IT IS POSSIBLE THAT IFR/LIFR
CEILINGS MAY DEVELOP BETWEEN 09-12Z SAT.
LOOKING AHEAD:
A STRONG COLD FRONT WILL TRACK EAST INTO CENTRAL NC SATURDAY
AFTERNOON. A LINE OF SHOWERS AND THUNDERSTORMS ARE EXPECTED ALONG
AND AHEAD OF THE FRONT. RAIN MAY LINGER INTO SATURDAY NIGHT AND
EARLY SUNDAY MORNING IN THE WAKE OF THE FRONTAL PASSAGE AT THE
FAY/RWI TERMINALS. VFR CONDITIONS WILL RULE IN THE WAKE OF THE COLD
FRONT SUNDAY THROUGH EARLY NEXT WEEK AS COOL AND DRY HIGH PRESSURE
BUILDS INTO THE CAROLINAS. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM....VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
705 AM EDT FRI SEP 7 2012
.SYNOPSIS...
LONG PERIOD SWELLS FROM HURRICANE LESLIE WILL IMPACT THE BEACHES
THROUGH THE WEEKEND...INCREASING THE RISK FOR STRONG AND FREQUENT RIP
CURRENTS AND LARGER THAN NORMAL BREAKERS. A WEAK RIDGE OF HIGH
PRESSURE WILL REMAIN ALONG THE COAST AS A TROUGH OF LOW PRESSURE
SLOWLY APPROACHES THE CAROLINAS FROM THE WEST TODAY. A STRONGER
FRONTAL SYSTEM WILL USHER IN FALL-LIKE WEATHER SUNDAY...WITH DRIER
AND COOLER HIGH PRESSURE BUILDING IN THROUGH NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...NO CHANGES HAVE BEEN MADE WITH RESPECT TO
ANTICIPATED COVERAGE OF AFTERNOON SHOWERS AND THUNDERSTORMS. CURRENT
RADAR LOOPS SHOW A CLUSTER OF SHOWERS IN GEORGETOWN COUNTY AND
PERHAPS HINTS OF ADDITIONAL DEVELOPMENT UPSTREAM THE SANTEE RIVER
ACROSS WILLIAMSBURG COUNTY. 06Z MODELS WERE SLIGHTLY COOLER WITH
AFTERNOON HIGHS SO A FEW SPOTS HAVE BEEN DROPPED BY A DEGREE.
CHANGES WERE ALL MINOR. PREVIOUS DISCUSSION FROM 330 AM FOLLOWS...
A WEAK 500 MB DISTURBANCE AND SURFACE TROUGH/OUTFLOW BOUNDARY HAVE
BEEN MAINTAINING SCATTERED CONVECTION THROUGH THE EARLY MORNING
HOURS. ACTIVITY HAS BEEN MOST PREVALENT IN THE SC PEE DEE REGION
WHERE RADAR ESTIMATES UP TO 4.50 INCHES OF RAIN EXIST ACROSS
PORTIONS OF FLORENCE...MARION AND WILLIAMSBURG COUNTIES.
THERMODYNAMICALLY THIS CONVECTION IS ELEVATED...ROOTED IN A LAYER
4000-7000 FT ABOVE THE GROUND. AS THE UPPER DISTURBANCES WEAKENS AND
PRESSES OFFSHORE IN THE NEXT COUPLE OF HOURS THE CONVECTION SHOULD
WEAKEN AS WELL. THE 04Z HRRR DID NOT INITIALIZE WELL...BUT EARLIER
RUNS (PARTICULARLY THE 01Z RUN) MODEL THE CURRENTLY OBSERVED
PATTERNS ON RADAR WELL.
LOW STRATUS CLOUDS ARE FILLING IN NORTH OF THE RAIN AREA AND MAY
SPREAD DOWN AS FAR SOUTH AS FLORENCE...MARION...WHITEVILLE AND
WILMINGTON BY DAYBREAK. AFTER PROVIDING A GLOOMY SUNRISE THESE
CLOUDS SHOULD BURN OFF BY 10:00 AM WITH AN EXPANSIVE CUMULUS FIELD
DEVELOPING IN ITS PLACE. TRIGGERS FOR AFTERNOON CONVECTION SHOULD
INCLUDE A WELL-DEFINED SEABREEZE...THE REMNANT OUTFLOW BOUNDARY FROM
THE EARLY MORNING CONVECTION ACROSS SOUTH CAROLINA...AND A
DIFFERENTIAL HEATING BOUNDARY AROUND THE EDGE OF THE MORNING LOW
STRATUS DECK. DESPITE NO SUPPORT FROM THE UPPER LEVELS AND A
FORECAST STORM CELL MOTION OF LESS THAN 5 MPH...I`M STILL INCLUDING
20 POPS INLAND AND 30 POPS NEAR THE COAST FOR THIS AFTERNOON GIVEN
ALL THE SURFACE BOUNDARIES AND WIDESPREAD 1500 J/KG SURFACE-BASED
CAPE EXPECTED.
ANY LINGERING CONVECTION SHOULD DIE AWAY QUICKLY THIS EVENING AS THE
BOUNDARY LAYER COOLS. THE ATMOSPHERE WILL BEGIN TO RESPOND TO AN
APPROACHING UPPER LEVEL TROUGH THAT WILL DRIVE A STRONG COLD FRONT
THROUGH THE CAROLINAS THIS WEEKEND. DEEP-LAYER FLOW THAT IS
ESSENTIALLY LIGHT AND VARIABLE THIS AFTERNOON WILL TURN SOUTHWEST
AND STEADILY INCREASE THROUGH THE NIGHT. SURFACE WINDS WILL NOT
INCREASE APPRECIABLY GIVEN THE STABLE LOW-LEVEL THERMAL PROFILES AT
NIGHT...BUT WINDS 1000 FT AGL AND HIGHER WILL PICK UP SPEED AFTER
MIDNIGHT.
HIGHS TODAY SHOULD REACH 90 OR SO INLAND...WITH UPPER 80S NEAR THE
COAST AND MID 80S ON THE BEACHES. LOWS TONIGHT WILL FALL INTO THE
LOWER TO MID 70S.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM FRIDAY...STRONG COLD FRONT WILL APPROACH THE AREA
SATURDAY MOVING THROUGH BY SUNDAY. LOCAL AREA WILL BE IN WARM
SECTOR ON SAT WITH DEEP LAYER MOISTURE MAKING ITS WAY IN A SW FLOW
LATER IN THE DAY AS MOISTURE POOLS AHEAD OF FRONT. GFS ACTUAL
SHOWS SOME DRIER AIR IN PLACE IN THE MID LEVELS INITIALLY THROUGH
THE AFTERNOON AND THEN PCP WATER VALUES SHOOT UP OVER 2 INCHES
THROUGH SAT EVENING. EXPECT BEST LIFT AND MOISTURE THROUGH THE
LATE EVENING AND OVERNIGHT AS MID TO UPPER TROUGH PUSHES COLD FRONT
THROUGH. POTENTIAL FOR STRONG TO SEVERE STORMS ESPECIALLY JUST
AHEAD OF FRONT. THE FRONT WILL MAKE IT THROUGH AFTER THE BEST
HEATING OF THE DAY AND THIS MAY WORK IN OUR FAVOR LIMITING MORE
WIDESPREAD STORMS.
THE SFC FRONT SHOULD MAKE IT OFF SHORE BY SUN MORNING BUT
WINDS IN THE LOW TO MID LEVELS WILL TAKE A LITTLE WHILE LONGER TO
VEER AROUND. PCP WATER VALUES WILL DROP OUT THROUGH SUNDAY DOWN
LESS THAN 1.5 INCHES BY SUN AFTN AND DROPPING EVEN FURTHER TO LESS
THAN AN INCH BY END OF THE PERIOD.
OVERALL EXPECT MORE LOCALIZED CONVECTION THROUGH SAT AFTN WITH
MORE WIDESPREAD ACTIVITY WITH APPROACH OF FRONT LATE SAT INTO
EARLY SUNDAY. THEN CLEARING THROUGH SUNDAY BEHIND FRONT AS PLENTY
OF DRY AIR MAKES IT WAY IN.
SAT WILL BE THE LAST DAY OF VERY WARM TEMPS AS 850 TEMPS REMAIN UP
NEAR 18 C BUT AS COOLER AIR ADVECTS IN ON SUNDAY...850 TEMPS WILL
FALL THROUGH THE DAY REACHING DOWN TO 10 C BY MON MORNING. MAX
TEMPS ON SAT WILL BE UP AROUND 90 OR SO WHILE SUNDAY THE TEMPS
WILL BE BETWEEN 80 AND 85 MOST PLACES WHILE DEWPOINT TEMPS DROP
ABOUT 10 DEGREES DOWN TO 60.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 300 AM FRIDAY...FALL LIKE WEATHER WILL EXIST THROUGH MUCH OF
NEXT WEEK AS COOL AND DRY HIGH PRESSURE BUILDS DOWN OVER THE
SOUTHEAST. BRIGHT SEPTEMBER SUN WILL PRODUCE MAX TEMPS BETWEEN 80
AND 85 MOST PLACES BUT THE VERY DRY AIR MASS WILL PRODUCE SOME
LARGE DIURNAL SWINGS. WITH DEWPOINT TEMPS DOWN INTO THE 50S
THROUGH AT LEAST WED AND WINDS DROPPING OFF EACH NIGHT...EXPECT
MORE IDEAL RADIATIONAL COOLING LEADING TO OVERNIGHT LOWS AROUND 60
WITH UPPER 50S INLAND. ACTUALLY TEMPS WILL BE CLOSE TO NORMAL AND
WILL CREEP UPWARD THROUGH MID WEEK AS H5 HEIGHTS RISE BACK UP WITH
RIDGE BUILDING IN THE SOUTHEAST. BY WED MOISTURE INCREASES ENOUGH
IN THE LOW LEVELS AS WINDS SHIFT AROUND TO THE NE TO PRODUCE SOME
CU AROUND. OVERALL EXPECT SUNNY AND DRY WEATHER THROUGH THE WEEK.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AS OF 12Z...THE CONVECTION HAS NOW EXITED THE COAST...ALONG WITH THE
DEEP MOISTURE. ORIGINALLY THOUGHT WE WOULD SEE BOUTS OF STRATUS FOR
THE FIRST COUPLE OF HOURS THIS MORNING...HOWEVER IT SEEMS MOST OF IT
HAS NOW DISSIPATED. MODELS INDICATE THERE WILL BE ENOUGH MOISTURE
ALONG THE IMMEDIATE COAST TO KICK OFF SCATTERED CONVECTION. BEST
CHANCE WILL BE AROUND MAX HEATING...WITH MOST OF THE ACTIVITY ENDING
BY 22Z. WINDS WILL BE A BIT SQUIRLY THIS MORNING WITH THE LIGHT
GRADIENT...BECOMING PREDOMINATELY EAST SOUTHEAST WITH THE RESULTANT
THIS AFTERNOON.
EXTENDED OUTLOOK...SCATTERED SHRA/TSRA THROUGH SUNDAY...WITH A CHANCE
OF EARLY MORNING LIFR/IFR CONDITIONS IN BR INLAND...AND MVFR AT THE
COAST. VFR MONDAY AND TUESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...NO CHANGES NEEDED TO THE MARINE FORECAST.
PREVIOUS DISCUSSION FROM 330 AM FOLLOWS...
A WEAK UPPER LEVEL DISTURBANCE AND SURFACE TROUGH ALONG THE CAROLINA
COAST IS RESPONSIBLE FOR SEVERAL WAVES OF SHOWERS AND THUNDERSTORMS
AFFECTING THE NC OFFSHORE WATER THIS MORNING. SCATTERED SHOWERS AND
STORMS SHOULD DIMINISH IN COVERAGE THROUGH THE EARLY MORNING HOURS
AS THIS DISTURBANCE PUSHES OFFSHORE AND WEAKENS FURTHER.
GENERALLY OFFSHORE WINDS EARLY THIS MORNING WILL TURN LIGHT AND
VARIABLE LATER THIS MORNING...AND THEN SOUTHERLY DRIVEN PRIMARILY BY
THE SEABREEZE THIS AFTERNOON. A STRONG COLD FRONT APPROACHING FROM
THE WEST WILL CREATE SLOWLY INCREASING SOUTHWEST WINDS TONIGHT.
SWELL FROM HURRICANE LESLIE HAS SHORTENED TO AROUND 10 SECONDS IN
PERIOD AND SHOULD CONTINUE THROUGH THE WEEKEND. ADDITIONAL SHORT
PERIOD WIND WAVES WILL ADD VERY LITTLE EXTRA TO THE TOTAL SEA
STATE...AND WE`RE EXPECTING 2-4 FT ACROSS THE SOUTH CAROLINA COASTAL
WATERS...AND 3-4 FT FOR THE NC COASTAL WATERS.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM FRIDAY...SOUTHWEST FLOW WILL INCREASE THROUGH SATURDAY
AHEAD OF APPROACHING COLD FRONT. SOUTHWEST WINDS UP AROUND 15 KTS
WILL VEER AROUND BECOMING OFF SHORE THROUGH SUNDAY MORNING AS COLD
FRONT MOVES THROUGH. THESE SOUTHWEST WINDS WILL COMBINE WITH
CONTINUED LONG PERIOD E-SE SWELLS TO PRODUCE SEAS IN THE 3 TO 5 FT
RANGE MOST PLACES THROUGH SATURDAY. THERE WILL BE SOME 6 FTERS IN
OUTER WATERS.
AS COLD FRONT MOVES FURTHER OFF SHORE THROUGH SUNDAY...WINDS WILL
VEER AROUND TO THE NORTH AROUND 10 TO 15 KTS AS HIGH PRESSURE
BUILDS IN FROM THE N-NW.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 300 AM FRIDAY...NORTHERLY WINDS WILL CONTINUE TO MIX WITH
LONGER PERIOD SWELLS FROM LESLIE TO PRODUCE SEAS IN THE 2 TO 4 FT
RANGE MOST WATERS. THE COOL NIGHTS WILL KEEP A WELL MIXED
ATMOSPHERE AS COOL AIR RIDES OVER THE WARM WATERS. THIS COULD
PRODUCE NORTHERLY WINDS UP TO 20 KTS OVERNIGHT. EXPECT SEAS CLOSER
TO 5 FT IN OUTER WATERS AND MAY SEE SEAS UP NEAR OR SLIGHTLY ABOVE
SCA EARLY MON IN NORTHERLY SURGE BEHIND FRONT. THE WINDS WILL
GRADUALLY SHIFT AROUND BECOMING NE TO E AS HIGH PRESSURE BUILDS
SOUTH AND EAST THROUGH MID WEEK.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
640 AM EDT FRI SEP 7 2012
.SYNOPSIS...
LONG PERIOD SWELLS FROM HURRICANE LESLIE WILL IMPACT THE BEACHES
THROUGH THE WEEKEND...INCREASING THE RISK FOR STRONG AND FREQUENT RIP
CURRENTS AND LARGER THAN NORMAL BREAKERS. A WEAK RIDGE OF HIGH
PRESSURE WILL REMAIN ALONG THE COAST AS A TROUGH OF LOW PRESSURE
SLOWLY APPROACHES THE CAROLINAS FROM THE WEST TODAY. A STRONGER
FRONTAL SYSTEM WILL USHER IN FALL-LIKE WEATHER SUNDAY...WITH DRIER
AND COOLER HIGH PRESSURE BUILDING IN THROUGH NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...NO CHANGES HAVE BEEN MADE WITH RESPECT TO
ANTICIPATED COVERAGE OF AFTERNOON SHOWERS AND THUNDERSTORMS. CURRENT
RADAR LOOPS SHOW A CLUSTER OF SHOWERS IN GEORGETOWN COUNTY AND
PERHAPS HINTS OF ADDITIONAL DEVELOPMENT UPSTREAM THE SANTEE RIVER
ACROSS WILLIAMSBURG COUNTY. 06Z MODELS WERE SLIGHTLY COOLER WITH
AFTERNOON HIGHS SO A FEW SPOTS HAVE BEEN DROPPED BY A DEGREE.
CHANGES WERE ALL MINOR. PREVIOUS DISCUSSION FROM 330 AM FOLLOWS...
A WEAK 500 MB DISTURBANCE AND SURFACE TROUGH/OUTFLOW BOUNDARY HAVE
BEEN MAINTAINING SCATTERED CONVECTION THROUGH THE EARLY MORNING
HOURS. ACTIVITY HAS BEEN MOST PREVALENT IN THE SC PEE DEE REGION
WHERE RADAR ESTIMATES UP TO 4.50 INCHES OF RAIN EXIST ACROSS
PORTIONS OF FLORENCE...MARION AND WILLIAMSBURG COUNTIES.
THERMODYNAMICALLY THIS CONVECTION IS ELEVATED...ROOTED IN A LAYER
4000-7000 FT ABOVE THE GROUND. AS THE UPPER DISTURBANCES WEAKENS AND
PRESSES OFFSHORE IN THE NEXT COUPLE OF HOURS THE CONVECTION SHOULD
WEAKEN AS WELL. THE 04Z HRRR DID NOT INITIALIZE WELL...BUT EARLIER
RUNS (PARTICULARLY THE 01Z RUN) MODEL THE CURRENTLY OBSERVED
PATTERNS ON RADAR WELL.
LOW STRATUS CLOUDS ARE FILLING IN NORTH OF THE RAIN AREA AND MAY
SPREAD DOWN AS FAR SOUTH AS FLORENCE...MARION...WHITEVILLE AND
WILMINGTON BY DAYBREAK. AFTER PROVIDING A GLOOMY SUNRISE THESE
CLOUDS SHOULD BURN OFF BY 10:00 AM WITH AN EXPANSIVE CUMULUS FIELD
DEVELOPING IN ITS PLACE. TRIGGERS FOR AFTERNOON CONVECTION SHOULD
INCLUDE A WELL-DEFINED SEABREEZE...THE REMNANT OUTFLOW BOUNDARY FROM
THE EARLY MORNING CONVECTION ACROSS SOUTH CAROLINA...AND A
DIFFERENTIAL HEATING BOUNDARY AROUND THE EDGE OF THE MORNING LOW
STRATUS DECK. DESPITE NO SUPPORT FROM THE UPPER LEVELS AND A
FORECAST STORM CELL MOTION OF LESS THAN 5 MPH...I`M STILL INCLUDING
20 POPS INLAND AND 30 POPS NEAR THE COAST FOR THIS AFTERNOON GIVEN
ALL THE SURFACE BOUNDARIES AND WIDESPREAD 1500 J/KG SURFACE-BASED
CAPE EXPECTED.
ANY LINGERING CONVECTION SHOULD DIE AWAY QUICKLY THIS EVENING AS THE
BOUNDARY LAYER COOLS. THE ATMOSPHERE WILL BEGIN TO RESPOND TO AN
APPROACHING UPPER LEVEL TROUGH THAT WILL DRIVE A STRONG COLD FRONT
THROUGH THE CAROLINAS THIS WEEKEND. DEEP-LAYER FLOW THAT IS
ESSENTIALLY LIGHT AND VARIABLE THIS AFTERNOON WILL TURN SOUTHWEST
AND STEADILY INCREASE THROUGH THE NIGHT. SURFACE WINDS WILL NOT
INCREASE APPRECIABLY GIVEN THE STABLE LOW-LEVEL THERMAL PROFILES AT
NIGHT...BUT WINDS 1000 FT AGL AND HIGHER WILL PICK UP SPEED AFTER
MIDNIGHT.
HIGHS TODAY SHOULD REACH 90 OR SO INLAND...WITH UPPER 80S NEAR THE
COAST AND MID 80S ON THE BEACHES. LOWS TONIGHT WILL FALL INTO THE
LOWER TO MID 70S.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM FRIDAY...STRONG COLD FRONT WILL APPROACH THE AREA
SATURDAY MOVING THROUGH BY SUNDAY. LOCAL AREA WILL BE IN WARM
SECTOR ON SAT WITH DEEP LAYER MOISTURE MAKING ITS WAY IN A SW FLOW
LATER IN THE DAY AS MOISTURE POOLS AHEAD OF FRONT. GFS ACTUAL
SHOWS SOME DRIER AIR IN PLACE IN THE MID LEVELS INITIALLY THROUGH
THE AFTERNOON AND THEN PCP WATER VALUES SHOOT UP OVER 2 INCHES
THROUGH SAT EVENING. EXPECT BEST LIFT AND MOISTURE THROUGH THE
LATE EVENING AND OVERNIGHT AS MID TO UPPER TROUGH PUSHES COLD FRONT
THROUGH. POTENTIAL FOR STRONG TO SEVERE STORMS ESPECIALLY JUST
AHEAD OF FRONT. THE FRONT WILL MAKE IT THROUGH AFTER THE BEST
HEATING OF THE DAY AND THIS MAY WORK IN OUR FAVOR LIMITING MORE
WIDESPREAD STORMS.
THE SFC FRONT SHOULD MAKE IT OFF SHORE BY SUN MORNING BUT
WINDS IN THE LOW TO MID LEVELS WILL TAKE A LITTLE WHILE LONGER TO
VEER AROUND. PCP WATER VALUES WILL DROP OUT THROUGH SUNDAY DOWN
LESS THAN 1.5 INCHES BY SUN AFTN AND DROPPING EVEN FURTHER TO LESS
THAN AN INCH BY END OF THE PERIOD.
OVERALL EXPECT MORE LOCALIZED CONVECTION THROUGH SAT AFTN WITH
MORE WIDESPREAD ACTIVITY WITH APPROACH OF FRONT LATE SAT INTO
EARLY SUNDAY. THEN CLEARING THROUGH SUNDAY BEHIND FRONT AS PLENTY
OF DRY AIR MAKES IT WAY IN.
SAT WILL BE THE LAST DAY OF VERY WARM TEMPS AS 850 TEMPS REMAIN UP
NEAR 18 C BUT AS COOLER AIR ADVECTS IN ON SUNDAY...850 TEMPS WILL
FALL THROUGH THE DAY REACHING DOWN TO 10 C BY MON MORNING. MAX
TEMPS ON SAT WILL BE UP AROUND 90 OR SO WHILE SUNDAY THE TEMPS
WILL BE BETWEEN 80 AND 85 MOST PLACES WHILE DEWPOINT TEMPS DROP
ABOUT 10 DEGREES DOWN TO 60.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 300 AM FRIDAY...FALL LIKE WEATHER WILL EXIST THROUGH MUCH OF
NEXT WEEK AS COOL AND DRY HIGH PRESSURE BUILDS DOWN OVER THE
SOUTHEAST. BRIGHT SEPTEMBER SUN WILL PRODUCE MAX TEMPS BETWEEN 80
AND 85 MOST PLACES BUT THE VERY DRY AIR MASS WILL PRODUCE SOME
LARGE DIURNAL SWINGS. WITH DEWPOINT TEMPS DOWN INTO THE 50S
THROUGH AT LEAST WED AND WINDS DROPPING OFF EACH NIGHT...EXPECT
MORE IDEAL RADIATIONAL COOLING LEADING TO OVERNIGHT LOWS AROUND 60
WITH UPPER 50S INLAND. ACTUALLY TEMPS WILL BE CLOSE TO NORMAL AND
WILL CREEP UPWARD THROUGH MID WEEK AS H5 HEIGHTS RISE BACK UP WITH
RIDGE BUILDING IN THE SOUTHEAST. BY WED MOISTURE INCREASES ENOUGH
IN THE LOW LEVELS AS WINDS SHIFT AROUND TO THE NE TO PRODUCE SOME
CU AROUND. OVERALL EXPECT SUNNY AND DRY WEATHER THROUGH THE WEEK.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 06Z...TSRA ACROSS THE PEE DEE REGION OF SC WILL SLIP
SOUTHEAST AND AWAY FROM FLORENCE OVER THE NEXT SEVERAL HOURS...BUT
MAY BRUSH BY MYR. BIGGER STORY WILL BE THE EXPANSION OF LOW
CEILINGS AT OR BELOW 600 FT AGL. THESE IFR CONDITIONS HAVE ALREADY
DEVELOPED AT LBT AND MAY EXPAND TO ILM AND FLO OVER THE NEXT
SEVERAL HOURS AS A WEAK CONVECTIVE OUTFLOW BOUNDARY SINKS SOUTH
ACROSS THE AREA.
AFTER DAYBREAK...ANY LINGERING FOG WILL QUICKLY DISSIPATE GIVING WAY
TO VFR ACROSS THE AREA. AS A SFC TROUGH CONTINUES TO PROGRESS ACROSS
THE AREA...EXPECT ISOLATED SHRA/TSRA DURING THE AFTERNOON HOURS
ALONG THE COAST...WHILE THE INLAND SITES ARE EXPECTED TO REMAIN
QUIET WITH VFR THROUGH THE REMAINDER OF THE PERIOD. BY THE
AFTERNOON...SOUTHWEST WINDS WILL BECOME SOUTH...INCREASING TO AOB 12
KTS. INTO THE EVENING HOURS...ACTIVITY WILL DIMINISH ALLOWING VFR TO
PREVAIL WITH DECREASING WINDS AND CLEARING SKIES.
EXTENDED OUTLOOK...SCATTERED SHRA/TSRA THROUGH SUNDAY...WITH A CHANCE
OF EARLY MORNING LIFR/IFR CONDITIONS IN BR INLAND...AND MVFR AT THE
COAST. VFR MONDAY AND TUESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...NO CHANGES NEEDED TO THE MARINE FORECAST.
PREVIOUS DISCUSSION FROM 330 AM FOLLOWS...
A WEAK UPPER LEVEL DISTURBANCE AND SURFACE TROUGH ALONG THE CAROLINA
COAST IS RESPONSIBLE FOR SEVERAL WAVES OF SHOWERS AND THUNDERSTORMS
AFFECTING THE NC OFFSHORE WATER THIS MORNING. SCATTERED SHOWERS AND
STORMS SHOULD DIMINISH IN COVERAGE THROUGH THE EARLY MORNING HOURS
AS THIS DISTURBANCE PUSHES OFFSHORE AND WEAKENS FURTHER.
GENERALLY OFFSHORE WINDS EARLY THIS MORNING WILL TURN LIGHT AND
VARIABLE LATER THIS MORNING...AND THEN SOUTHERLY DRIVEN PRIMARILY BY
THE SEABREEZE THIS AFTERNOON. A STRONG COLD FRONT APPROACHING FROM
THE WEST WILL CREATE SLOWLY INCREASING SOUTHWEST WINDS TONIGHT.
SWELL FROM HURRICANE LESLIE HAS SHORTENED TO AROUND 10 SECONDS IN
PERIOD AND SHOULD CONTINUE THROUGH THE WEEKEND. ADDITIONAL SHORT
PERIOD WIND WAVES WILL ADD VERY LITTLE EXTRA TO THE TOTAL SEA
STATE...AND WE`RE EXPECTING 2-4 FT ACROSS THE SOUTH CAROLINA COASTAL
WATERS...AND 3-4 FT FOR THE NC COASTAL WATERS.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM FRIDAY...SOUTHWEST FLOW WILL INCREASE THROUGH SATURDAY
AHEAD OF APPROACHING COLD FRONT. SOUTHWEST WINDS UP AROUND 15 KTS
WILL VEER AROUND BECOMING OFF SHORE THROUGH SUNDAY MORNING AS COLD
FRONT MOVES THROUGH. THESE SOUTHWEST WINDS WILL COMBINE WITH
CONTINUED LONG PERIOD E-SE SWELLS TO PRODUCE SEAS IN THE 3 TO 5 FT
RANGE MOST PLACES THROUGH SATURDAY. THERE WILL BE SOME 6 FTERS IN
OUTER WATERS.
AS COLD FRONT MOVES FURTHER OFF SHORE THROUGH SUNDAY...WINDS WILL
VEER AROUND TO THE NORTH AROUND 10 TO 15 KTS AS HIGH PRESSURE
BUILDS IN FROM THE N-NW.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 300 AM FRIDAY...NORTHERLY WINDS WILL CONTINUE TO MIX WITH
LONGER PERIOD SWELLS FROM LESLIE TO PRODUCE SEAS IN THE 2 TO 4 FT
RANGE MOST WATERS. THE COOL NIGHTS WILL KEEP A WELL MIXED
ATMOSPHERE AS COOL AIR RIDES OVER THE WARM WATERS. THIS COULD
PRODUCE NORTHERLY WINDS UP TO 20 KTS OVERNIGHT. EXPECT SEAS CLOSER
TO 5 FT IN OUTER WATERS AND MAY SEE SEAS UP NEAR OR SLIGHTLY ABOVE
SCA EARLY MON IN NORTHERLY SURGE BEHIND FRONT. THE WINDS WILL
GRADUALLY SHIFT AROUND BECOMING NE TO E AS HIGH PRESSURE BUILDS
SOUTH AND EAST THROUGH MID WEEK.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...TRA/SGL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
547 AM EDT FRI SEP 7 2012
.SYNOPSIS...
A WEAK SURFACE TROUGH WILL STALL OVER THE EASTERN CAROLINAS TODAY. A
DEEPENING LOW PRESSURE SYSTEM OVER THE GREAT LAKES WILL PUSH A
STRONG COLD FRONT THROUGH THE CAROLINAS SATURDAY AFTERNOON AND
EVENING. COOLER AND DRIER CONDITIONS WILL PREVAIL IN THE WAKE OF THE
FRONT SUNDAY THROUGH EARLY NEXT WEEK AS HIGH PRESSURE BUILDS INTO
THE REGION.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 330 AM FRIDAY...
OVERVIEW:
AN H5 SHORTWAVE CENTERED NEAR THE HWY 1 CORRIDOR AT 06Z THIS MORNING
IS EXPECTED TO TRACK SLOWLY EAST TOWARD THE CAROLINA COAST THIS
AFTERNOON BEFORE FURTHER WEAKENING AND SHIFTING OFFSHORE THIS
EVENING/TONIGHT. A SFC-H85 TROUGH ATTENDANT THE SHORTWAVE IS PROGGED
TO STALL OUT OVER THE COASTAL PLAIN TODAY...THEN DISSIPATE TONIGHT
AS HEIGHT FALLS OVERSPREAD THE AREA FROM WEST-EAST IN ADVANCE OF AN
AMPLIFYING UPPER LEVEL TROUGH AND ASSOCIATED SURFACE COLD FRONT
PROGRESSING INTO THE OH VALLEY.
PRECIPITATION CHANCES:
MOISTURE THROUGHOUT THE COLUMN WILL VARY WIDELY ACROSS THE AREA
TODAY...BETWEEN A DRY AIRMASS (PWAT VALUES ~1.00") OVER THE
MOUNTAINS AND A VERY MOIST AIRMASS (PWAT VALUES ~2.00") OVER THE
COASTAL CAROLINAS WHERE THE AFOREMENTIONED SFC-H85 TROUGH IS PROGGED
TO STALL OUT. THE LATEST GFS/RAP MODEL GUIDANCE INDICATES THE DRIER
AIRMASS TO THE NORTH AND WEST ADVECTING INTO CENTRAL NC THROUGHOUT
THE MORNING...WITH PWAT VALUES FALLING TO 1.00-1.25" OVER THE BULK
OF THE AREA...EXCEPT THE SOUTHEAST COASTAL PLAIN WHERE PWAT VALUES
MAY LINGER NEAR ~1.75". THE LATEST 00Z NAM APPEARS TO BE AN
OUTLIER...INDICATING DEEPER MOISTURE LINGERING MUCH FURTHER WEST (TO
THE TRIANGLE/HWY 1 CORRIDOR) THAN EITHER THE 00Z GFS OR 06Z RAP.
GIVEN THAT THE GFS HAS SUPPORT FROM THE MOST RECENT RAP MODEL RUN...
THE NAM WILL BE DISREGARD AT THIS TIME. ANTICIPATE THAT INSTABILITY
WILL GENERALLY BE CONFINED TO AREAS SOUTH AND EAST OF THE TRIANGLE
DURING PEAK HEATING...WITH MLCAPE VALUES RANGING FROM 500-1500 J/KG
IN THE SOUTHEAST COASTAL PLAIN...PRIMARILY IN CUMBERLAND/SAMPSON/
WAYNE COUNTIES. SOME UNCERTAINTY IS PRESENT...AND THE INSTABILITY
AXIS COULD BE SLIGHTLY FURTHER TO THE EAST OR WEST...DEPENDING ON
THE LOCATION OF THE SFC-H85 TROUGH. FORCING FOR ASCENT TODAY WILL
PRIMARILY BE ASSOCIATED WITH LOW-LEVEL CONVERGENCE IN VICINITY OF
THE SEABREEZE AND THE SFC-H85 TROUGH OVER THE COASTAL CAROLINAS.
SHORTWAVE ENERGY PROGRESSING INTO ILLINOIS AT 06Z WILL PROGRESS EAST
THROUGH THE MID-ATLANTIC THIS AFTERNOON...RESULTING IN WEAK DPVA
OVER NORTHERN PORTIONS OF THE STATE. WITH THE ABOVE IN MIND...WILL
INDICATE A 20-30% CHANCE OF SHOWERS/STORMS IN THE SOUTHEAST COASTAL
PLAIN CLOSER TO THE BEST MOISTURE/INSTABILITY AND LOW-LEVEL FORCING
DURING PEAK HEATING. ANTICIPATE THAT THE DRIER /MORE STABLE/ AIRMASS
IN PLACE OVER NORTHERN PORTIONS OF THE AREA WILL PRECLUDE A CHANCE
FOR CONVECTION WITH THE AFOREMENTIONED SHORTWAVE ENERGY. WILL KEEP
THE FORECAST DRY OVERNIGHT.
TEMPERATURES:
GIVEN LESS CLOUD COVER AND 1000-850 MB THICKNESSES SIMILAR TO
PREVIOUS DAYS...EXPECT HIGHS IN THE UPPER 80S TO 90-91F. LOWS
TONIGHT IN THE UPPER 60S TO LOWER 70S...WARMEST WHERE A LIGHT
SOUTHERLY BREEZE IS PRESENT AS THE MSLP GRADIENT BEGINS TO TIGHTEN
FROM THE WEST PRIOR TO SUNRISE.
HAZARDOUS WEATHER:
CONVECTION ALLOWING MODELS DEVELOP ISOLD CONVECTION OVER THE FAR
SOUTHEAST COASTAL PLAIN THIS AFTERNOON...IN ASSOC/W THE LINGERING
SFC-H85 TROUGH AND/OR THE SEABREEZE. DEEP-LAYER SHEAR WILL BE
NEGLIGIBLE TODAY (< 15 KT IN SOUTHEAST NC)...AND DESTABILIZATION IS
EXPECTED TO YIELD RELATIVELY MARGINAL INSTABILITY WITH MLCAPE VALUES
IN THE 500-1500 J/KG RANGE...SO ANY CONVECTION THAT DEVELOPS WILL BE
UNORGANIZED AND SHORT-LIVED. HOWEVER...THE ADVECTION OF A DRIER
MID-LEVEL AIRMASS INTO THE AREA WILL RESULT IN A MARKED INCREASE IN
DCAPE THIS AFTERNOON...EVEN IN THE SOUTHEAST COASTAL PLAIN...WHERE
VIRTUALLY ALL MODEL GUIDANCE INDICATE VALUES IN THE 1000-1500 J/KG
RANGE. WITH THIS IN MIND...AN ISOLD UPDRAFT INTERACTING WITH OR
ENHANCED BY OUTFLOW IN THE PRESENCE OF RELATIVELY HIGH DCAPE COULD
YIELD A BRIEF/ISOLD INSTANCE OF DAMAGING WIND...PRIMARILY IN
CUMBERLAND/SAMPSON/WAYNE COUNTIES...THOUGH THE PROBABILITY IS TOO
LOW TO MENTION IN THE HAZARDOUS WEATHER OUTLOOK. -VINCENT
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 303 AM FRIDAY...
...SLIGHT CHANCE OF SEVERE THUNDERSTORMS SATURDAY AFTERNOON AND
EARLY EVENING...
THE BIG PATTERN CHANGE THAT HAS BEEN ADVERTISED FOR DAYS WILL START
WITH A BANG SATURDAY AFTERNOON. A POSITIVELY TILTED MID-UPPER TROUGH
IS FORECAST TO AMPLIFY AS IT DIVES SE ACROSS THE CENTRAL
APPALACHIANS AND MID-ATLANTIC STATES SATURDAY AFTERNOON. THE
ASSOCIATED COLD FRONT WILL PUSH INTO THE REGION DURING PEAK HEATING.
THE THE MOST FAVORABLE WINDS ALOFT FOR ORGANIZED SEVERE STORMS MAY
REMAIN JUST TO OUR NORTH. HOWEVER... STRONG SURFACE HEATING IS
EXPECTED TO DESTABILIZE THE BOUNDARY LAYER BY EARLY AFTERNOON OUT
AHEAD OF A PRE-FRONTAL TROUGH/REMNANT CONVECTIVE OUTFLOW BOUNDARY.
THIS BOUNDARY SHOULD BEGIN TO ARRIVE DURING PEAK HEATING FOR MUCH OF
CENTRAL NORTH CAROLINA. WITH STRONG HEATING... TEMPERATURES SHOULD
REACH AROUND 90 BY EARLY AFTERNOON THROUGHOUT MOST OF THE REGION.
THIS WILL COMBINE WITH DEW POINTS FORECAST TO BE IN THE LOWER 70S TO
PRODUCE FAVORABLE PARAMETERS FOR MULTICELL STORM CLUSTERS. A FEW
OF THESE STORMS MAY BECOME SEVERE WITH THE MAIN THREAT BEING
DAMAGING WET DOWNBURSTS. THE MULTICELL CLUSTERS MAY EVOLVE INTO A
LINE BY LATE AFTERNOON AGAIN FAVORING ISOLATED DAMAGING WIND GUSTS
ALONG LEWP/BOWING SEGMENTS. THERE MAY BE A FINAL LINE OF CONVECTION
WITH THE MAIN COLD FRONT LATER IN THE DAY OR EVENING. REGARDLESS...
SATURDAY AFTERNOON AND EVENING IS EXPECTED TO BE ACTIVE ONCE AGAIN.
IN ADDITION TO THE SLIGHT CHANCE OF SEVERE STORMS... FREQUENT CG
LIGHTNING AND LOCALLY HEAVY RAIN IS AGAIN EXPECTED WITH THE STORMS.
EARLY MORNING STRATUS WILL GIVE WAY TO PARTLY SUNNY SKIES. WE WILL
CARRY LIKELY POP FOR SHOWERS AND THUNDERSTORMS IN THE AFTERNOON AND
EVENING. HIGHS 90-93 EXCEPT UPPER 80S NW.
THE STORMS WILL GRADUALLY END SATURDAY EVENING NW... AND ELSEWHERE
OVERNIGHT WITH THE ACTUAL COLD FRONTAL PASSAGE. GOOD DRY/COOL AIR
ADVECTION WILL ARRIVE MAINLY BETWEEN 06Z-12Z. THIS LATE CAA ARRIVAL
COMBINED WITH LINGER CLOUDS SHOULD KEEP LOWS MILD AND LIKELY ABOVE
GUIDANCE. WE WILL CARRY 60-65 MOST AREAS.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 303 AM FRIDAY...
A LONG AWAITED BREATHER FROM ALL THE VERY WARM/HUMID/THUNDERY
WEATHER WILL BEGIN SUNDAY. A REFRESHING BREEZE WILL COMBINE WITH
AMPLE SUNSHINE TO BRING A SPRING-LIKE FEEL. HIGHS OF 78-83 EXPECTED
(WITH DEW POINTS IN THE 40S NW AND LOWER 50S SE). A NORTHERLY BREEZE
AT 10-15 MPH WILL MAKE IT FEEL APRIL-FRESH AT TIMES.
MONDAY THROUGH THURSDAY...
EXPECT DRY AND SEASONABLY COOL CONDITIONS MONDAY AND TUESDAY... WITH
MODERATING DAYTIME TEMPS WED AND THUR. MOSTLY CLEAR/MOSTLY SUNNY
WITH LOWS IN THE 50S EACH DAY. HIGHS 75 TO 80 MON-TUE... WARMING
INTO THE LOWER TO MID 80S BY THURSDAY.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 155 AM FRIDAY...
24-HR TAF PERIOD:
IFR TO VLIFR CEILINGS AND VISBYS ARE PRESENT OVER PORTIONS OF THE
NORTHERN PIEDMONT (INCLUDING RDU/RWI) AS OF 06Z. GIVEN A VERY MOIST
LOW-LEVEL AIRMASS...LIGHT/CALM WINDS...AND A DRIER MID-LEVEL AIRMASS
PROGRESSING INTO THE AREA FROM THE NORTHWEST...EXPECT THAT ALL TAF
SITES WILL SEE CONDITIONS DETERIORATE INTO THE IFR TO VLIFR RANGE
BETWEEN 06-12Z THIS MORNING. FOG AND LOW CEILINGS ARE EXPECTED TO
LIFT AND SCATTER TO VFR BETWEEN 12-15Z AT INT/GSO/RDU. CONDITIONS
SHOULD BE SLOWER TO IMPROVE AT THE FAY/RWI TERMINALS WHERE MOISTURE
IS DEEPER AND MVFR CEILINGS MAY PERSIST THROUGH ~18Z. ISOLATED
SHOWERS AND STORMS WILL BE POSSIBLE DURING THE AFTERNOON...THOUGH
CHANCES WILL MOST LIKELY BE LIMITED TO THE FAY TERMINAL.
OTHERWISE...EXPECT VFR CONDITIONS TO PREVAIL THIS AFTERNOON THROUGH
06Z TONIGHT. LOW-LEVEL SOUTHERLY FLOW WILL STRENGTHEN PRIOR TO
SUNRISE SATURDAY IN ADVANCE OF AN APPROACHING COLD FRONT...AND IT IS
POSSIBLE THAT MVFR/IFR CEILINGS MAY DEVELOP BETWEEN 09-12Z SAT.
LOOKING AHEAD:
A STRONG COLD FRONT WILL TRACK EAST INTO CENTRAL NC SATURDAY
AFT/EVE. A LINE OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ALONG
AND AHEAD OF THE FRONT. RAIN MAY LINGER INTO SATURDAY NIGHT AND
EARLY SUNDAY MORNING IN THE WAKE OF THE FRONTAL PASSAGE...PRIMARILY
AT THE FAY/RWI TERMINALS. VFR CONDITIONS WILL RULE IN THE WAKE OF
THE COLD FRONT SUNDAY THROUGH EARLY NEXT WEEK AS COOL AND DRY HIGH
PRESSURE BUILDS INTO THE CAROLINAS. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM....VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
402 AM EDT FRI SEP 7 2012
.SYNOPSIS...
LONG PERIOD SWELLS FROM LESLIE WILL IMPACT THE BEACHES THROUGH
THE WEEKEND...INCREASING THE RISK FOR STRONG AND FREQUENT RIP
CURRENTS AND LARGER THAN NORMAL BREAKERS. SOME BEACH EROSION MAY
EVEN BE OBSERVED. A WEAK RIDGE OF HIGH PRESSURE WILL REMAIN ALONG
THE COAST AS A TROUGH OF LOW PRESSURE SLOWLY APPROACHES THE
CAROLINAS FROM THE WEST TODAY. A STRONGER FRONTAL SYSTEM
WILL USHER IN FALL-LIKE WEATHER SUNDAY...WITH DRIER AND COOLER
HIGH PRESSURE BUILDING IN THROUGH NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM FRIDAY...A WEAK 500 MB DISTURBANCE AND SURFACE TROUGH/
OUTFLOW BOUNDARY HAVE BEEN MAINTAINING SCATTERED CONVECTION THROUGH
THE EARLY MORNING HOURS. ACTIVITY HAS BEEN MOST PREVALENT IN THE SC
PEE DEE REGION WHERE RADAR ESTIMATES UP TO 4.50 INCHES OF RAIN EXIST
ACROSS PORTIONS OF FLORENCE...MARION AND WILLIAMSBURG COUNTIES.
THERMODYNAMICALLY THIS CONVECTION IS ELEVATED...ROOTED IN A LAYER
4000-7000 FT ABOVE THE GROUND. AS THE UPPER DISTURBANCES WEAKENS AND
PRESSES OFFSHORE IN THE NEXT COUPLE OF HOURS THE CONVECTION SHOULD
WEAKEN AS WELL. THE 04Z HRRR DID NOT INITIALIZE WELL...BUT EARLIER
RUNS (PARTICULARLY THE 01Z RUN) MODEL THE CURRENTLY OBSERVED
PATTERNS ON RADAR WELL.
LOW STRATUS CLOUDS ARE FILLING IN NORTH OF THE RAIN AREA AND MAY
SPREAD DOWN AS FAR SOUTH AS FLORENCE...MARION...WHITEVILLE AND
WILMINGTON BY DAYBREAK. AFTER PROVIDING A GLOOMY SUNRISE THESE
CLOUDS SHOULD BURN OFF BY 10:00 AM WITH AN EXPANSIVE CUMULUS FIELD
DEVELOPING IN ITS PLACE. TRIGGERS FOR AFTERNOON CONVECTION SHOULD
INCLUDE A WELL-DEFINED SEABREEZE...THE REMNANT OUTFLOW BOUNDARY FROM
THE EARLY MORNING CONVECTION ACROSS SOUTH CAROLINA...AND A
DIFFERENTIAL HEATING BOUNDARY AROUND THE EDGE OF THE MORNING LOW
STRATUS DECK. DESPITE NO SUPPORT FROM THE UPPER LEVELS AND A
FORECAST STORM CELL MOTION OF LESS THAN 5 MPH...I`M STILL INCLUDING
20 POPS INLAND AND 30 POPS NEAR THE COAST FOR THIS AFTERNOON GIVEN
ALL THE SURFACE BOUNDARIES AND WIDESPREAD 1500 J/KG SURFACE-BASED
CAPE EXPECTED.
ANY LINGERING CONVECTION SHOULD DIE AWAY QUICKLY THIS EVENING AS THE
BOUNDARY LAYER COOLS. THE ATMOSPHERE WILL BEGIN TO RESPOND TO AN
APPROACHING UPPER LEVEL TROUGH THAT WILL DRIVE A STRONG COLD FRONT
THROUGH THE CAROLINAS THIS WEEKEND. DEEP-LAYER FLOW THAT IS
ESSENTIALLY LIGHT AND VARIABLE THIS AFTERNOON WILL TURN SOUTHWEST
AND STEADILY INCREASE THROUGH THE NIGHT. SURFACE WINDS WILL NOT
INCREASE APPRECIABLY GIVEN THE STABLE LOW-LEVEL THERMAL PROFILES AT
NIGHT...BUT WINDS 1000 FT AGL AND HIGHER WILL PICK UP SPEED AFTER
MIDNIGHT.
HIGHS TODAY SHOULD REACH 90 OR SO INLAND...WITH UPPER 80S NEAR THE
COAST AND MID 80S ON THE BEACHES. LOWS TONIGHT WILL FALL INTO THE
LOWER TO MID 70S.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM FRIDAY...STRONG COLD FRONT WILL APPROACH THE AREA
SATURDAY MOVING THROUGH BY SUNDAY. LOCAL AREA WILL BE IN WARM
SECTOR ON SAT WITH DEEP LAYER MOISTURE MAKING ITS WAY IN A SW FLOW
LATER IN THE DAY AS MOISTURE POOLS AHEAD OF FRONT. GFS ACTUAL
SHOWS SOME DRIER AIR IN PLACE IN THE MID LEVELS INITIALLY THROUGH
THE AFTERNOON AND THEN PCP WATER VALUES SHOOT UP OVER 2 INCHES
THROUGH SAT EVENING. EXPECT BEST LIFT AND MOISTURE THROUGH THE
LATE EVENING AND OVERNIGHT AS MID TO UPPER TROUGH PUSHES COLD FRONT
THROUGH. POTENTIAL FOR STRONG TO SEVERE STORMS ESPECIALLLY JUST
AHEAD OF FRONT. THE FRONT WILL MAKE IT THROUGH AFTER THE BEST
HEATING OF THE DAY AND THIS MAY WORK IN OUR FAVOR LIMITING MORE
WIDESPREAD STORMS.
THE SFC FRONT SHOULD MAKE IT OFF SHORE BY SUN MORNING BUT
WINDS IN THE LOW TO MID LEVELS WILL TAKE A LITTLE WHILE LONGER TO
VEER AROUND. PCP WATER VALUES WILL DROP OUT THROUGH SUNDAY DOWN
LESS THAN 1.5 INCHES BY SUN AFTN AND DROPPING EVEN FURTHER TO LESS
THAN AN INCH BY END OF THE PERIOD.
OVERALL EXPECT MORE LOCALIZED CONVECTION THROUGH SAT AFTN WITH
MORE WIDESPREAD ACTIVITY WITH APPROACH OF FRONT LATE SAT INTO
EARLY SUNDAY. THEN CLEARING THROUGH SUNDAY BEHIND FRONT AS PLENTY
OF DRY AIR MAKES IT WAY IN.
SAT WILL BE THE LAST DAY OF VERY WARM TEMPS AS 850 TEMPS REMAIN UP
NEAR 18 C BUT AS COOLER AIR ADVECTS IN ON SUNDAY...850 TEMPS WILL
FALL THROUGH THE DAY REACHING DOWN TO 10 C BY MON MORNING. MAX
TEMPS ON SAT WILL BE UP AROUND 90 OR SO WHILE SUNDAY THE TEMPS
WILL BE BETWEEN 80 AND 85 MOST PLACES WHILE DEWPOINT TEMPS DROP
ABOUT 10 DEGREES DOWN TO 60.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 300 AM FRIDAY...FALL LIKE WEATHER WILL EXIST THROUGH MUCH OF
NEXT WEEK AS COOL AND DRY HIGH PRESSURE BUILDS DOWN OVER THE
SOUTHEAST. BRIGHT SEPTEMBER SUN WILL PRODUCE MAX TEMPS BETWEEN 80
AND 85 MOST PLACES BUT THE VERY DRY AIR MASS WILL PRODUCE SOME
LARGE DIURNAL SWINGS. WITH DEWPOINT TEMPS DOWN INTO THE 50S
THROUGH AT LEAST WED AND WINDS DROPPING OFF EACH NIGHT...EXPECT
MORE IDEAL RADIATIONAL COOLING LEADING TO OVERNIGHT LOWS AROUND 60
WITH UPPER 50S INLAND. ACTUALLY TEMPS WILL BE CLOSE TO NORMAL AND
WILL CREEP UPWARD THROUGH MID WEEK AS H5 HEIGHTS RISE BACK UP WITH
RIDGE BUILDING IN THE SOUTHEAST. BY WED MOISTURE INCREASES ENOUGH
IN THE LOW LEVELS AS WINDS SHIFT AROUND TO THE NE TO PRODUCE SOME
CU AROUND. OVERALL EXPECT SUNNY AND DRY WEATHER THROUGH THE WEEK.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 06Z...TSRA ACROSS THE PEE DEE REGION OF SC WILL SLIP
SOUTHEAST AND AWAY FROM FLORENCE OVER THE NEXT SEVERAL HOURS...BUT
MAY BRUSH BY MYR. BIGGER STORY WILL BE THE EXPANSION OF LOW
CEILINGS AT OR BELOW 600 FT AGL. THESE IFR CONDITIONS HAVE ALREADY
DEVELOPED AT LBT AND MAY EXPAND TO ILM AND FLO OVER THE NEXT
SEVERAL HOURS AS A WEAK CONVECTIVE OUTFLOW BOUNDARY SINKS SOUTH
ACROSS THE AREA.
AFTER DAYBREAK...ANY LINGERING FOG WILL QUICKLY DISSIPATE GIVING WAY
TO VFR ACROSS THE AREA. AS A SFC TROUGH CONTINUES TO PROGRESS ACROSS
THE AREA...EXPECT ISOLATED SHRA/TSRA DURING THE AFTERNOON HOURS
ALONG THE COAST...WHILE THE INLAND SITES ARE EXPECTED TO REMAIN
QUIET WITH VFR THROUGH THE REMAINDER OF THE PERIOD. BY THE
AFTERNOON...SOUTHWEST WINDS WILL BECOME SOUTH...INCREASING TO AOB 12
KTS. INTO THE EVENING HOURS...ACTIVITY WILL DIMINISH ALLOWING VFR TO
PREVAIL WITH DECREASING WINDS AND CLEARING SKIES.
EXTENDED OUTLOOK...SCATTERED SHRA/TSRA THROUGH SUNDAY...WITH A CHANCE
OF EARLY MORNING LIFR/IFR CONDITIONS IN BR INLAND...AND MVFR AT THE
COAST. VFR MONDAY AND TUESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM FRIDAY...A WEAK UPPER LEVEL DISTURBANCE AND SURFACE
TROUGH ALONG THE CAROLINA COAST IS RESPONSIBLE FOR SEVERAL WAVES OF
SHOWERS AND THUNDERSTORMS AFFECTING THE NC OFFSHORE WATER THIS
MORNING. SCATTERED SHOWERS AND STORMS SHOULD DIMINISH IN COVERAGE
THROUGH THE EARLY MORNING HOURS AS THIS DISTURBANCE PUSHES OFFSHORE
AND WEAKENS FURTHER.
GENERALLY OFFSHORE WINDS EARLY THIS MORNING WILL TURN LIGHT AND
VARIABLE LATER THIS MORNING...AND THEN SOUTHERLY DRIVEN PRIMARILY BY
THE SEABREEZE THIS AFTERNOON. A STRONG COLD FRONT APPROACHING FROM
THE WEST WILL CREATE SLOWLY INCREASING SOUTHWEST WINDS TONIGHT.
SWELL FROM HURRICANE LESLIE HAS SHORTENED TO AROUND 10 SECONDS IN
PERIOD AND SHOULD CONTINUE THROUGH THE WEEKEND. ADDITIONAL SHORT
PERIOD WIND WAVES WILL ADD VERY LITTLE EXTRA TO THE TOTAL SEA
STATE...AND WE`RE EXPECTING 2-4 FT ACROSS THE SOUTH CAROLINA COASTAL
WATERS...AND 3-4 FT FOR THE NC COASTAL WATERS.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM FRIDAY...SOUTHWEST FLOW WILL INCREASE THROUGH SATURDAY
AHEAD OF APPROACHING COLD FRONT. SOUTHWEST WINDS UP AROUND 15 KTS
WILL VEER AROUND BECOMING OFF SHORE THROUGH SUNDAY MORNING AS COLD
FRONT MOVES THROUGH. THESE SOUTHWEST WINDS WILL COMBINE WITH
CONTINUED LONG PERIOD E-SE SWELLS TO PRODUCE SEAS IN THE 3 TO 5 FT
RANGE MOST PLACES THROUGH SATURDAY. THERE WILL BE SOME 6 FTERS IN
OUTER WATERS.
AS COLD FRONT MOVES FURTHER OFF SHORE THROUGH SUNDAY...WINDS WILL
VEER AROUND TO THE NORTH AROUND 10 TO 15 KTS AS HIGH PRESSURE
BUILDS IN FROM THE N-NW.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 300 AM FRIDAY...NORTHERLY WINDS WILL CONTINUE TO MIX WITH
LONGER PERIOD SWELLS FROM LESLIE TO PRODUCE SEAS IN THE 2 TO 4 FT
RANGE MOST WATERS. THE COOL NIGHTS WILL KEEP A WELL MIXED
ATMOSPHERE AS COOL AIR RIDES OVER THE WARM WATERS. THIS COULD
PRODUCE NORTHERLY WINDS UP TO 20 KTS OVERNIGHT. EXPECT SEAS CLOSER
TO 5 FT IN OUTER WATERS AND MAY SEE SEAS UP NEAR OR SLIGHTLY ABOVE
SCA EARLY MON IN NORTHERLY SURGE BEHIND FRONT. THE WINDS WILL
GRADUALLY SHIFT AROUND BECOMING NE TO E AS HIGH PRESSURE BUILDS
SOUTH AND EAST THROUGH MID WEEK.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...TRA/SGL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
339 AM EDT FRI SEP 7 2012
.SYNOPSIS...
A WEAK SURFACE TROUGH WILL STALL OVER THE EASTERN CAROLINAS TODAY. A
DEEPENING LOW PRESSURE SYSTEM OVER THE GREAT LAKES WILL PUSH A
STRONG COLD FRONT THROUGH THE CAROLINAS SATURDAY AFTERNOON AND
EVENING. COOLER AND DRIER CONDITIONS WILL PREVAIL IN THE WAKE OF THE
FRONT SUNDAY THROUGH EARLY NEXT WEEK AS HIGH PRESSURE BUILDS INTO
THE REGION.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 330 AM FRIDAY...
OVERVIEW:
AN H5 SHORTWAVE CENTERED NEAR THE HWY 1 CORRIDOR AT 06Z THIS MORNING
IS EXPECTED TO TRACK SLOWLY EAST TOWARD THE CAROLINA COAST THIS
AFTERNOON BEFORE FURTHER WEAKENING AND SHIFTING OFFSHORE THIS
EVENING/TONIGHT. A SFC-H85 TROUGH ATTENDANT THE SHORTWAVE IS PROGGED
TO STALL OUT OVER THE COASTAL PLAIN TODAY...THEN DISSIPATE TONIGHT
AS HEIGHT FALLS OVERSPREAD THE AREA FROM WEST-EAST IN ADVANCE OF AN
AMPLIFYING UPPER LEVEL TROUGH AND ASSOCIATED SURFACE COLD FRONT
PROGRESSING INTO THE OH VALLEY.
PRECIPITATION CHANCES:
MOISTURE THROUGHOUT THE COLUMN WILL VARY WIDELY ACROSS THE AREA
TODAY...BETWEEN A DRY AIRMASS (PWAT VALUES ~1.00") OVER THE
MOUNTAINS AND A VERY MOIST AIRMASS (PWAT VALUES ~2.00") OVER THE
COASTAL CAROLINAS WHERE THE AFOREMENTIONED SFC-H85 TROUGH IS PROGGED
TO STALL OUT. THE LATEST GFS/RAP MODEL GUIDANCE INDICATES THE DRIER
AIRMASS TO THE NORTH AND WEST ADVECTING INTO CENTRAL NC THROUGHOUT
THE MORNING...WITH PWAT VALUES FALLING TO 1.00-1.25" OVER THE BULK
OF THE AREA...EXCEPT THE SOUTHEAST COASTAL PLAIN WHERE PWAT VALUES
MAY LINGER NEAR ~1.75". THE LATEST 00Z NAM APPEARS TO BE AN
OUTLIER...INDICATING DEEPER MOISTURE LINGERING MUCH FURTHER WEST (TO
THE TRIANGLE/HWY 1 CORRIDOR) THAN EITHER THE 00Z GFS OR 06Z RAP.
GIVEN THAT THE GFS HAS SUPPORT FROM THE MOST RECENT RAP MODEL RUN...
THE NAM WILL BE DISREGARD AT THIS TIME. ANTICIPATE THAT INSTABILITY
WILL GENERALLY BE CONFINED TO AREAS SOUTH AND EAST OF THE TRIANGLE
DURING PEAK HEATING...WITH MLCAPE VALUES RANGING FROM 1000-1500 J/KG
IN THE SOUTHEAST COASTAL PLAIN...PRIMARILY IN CUMBERLAND/SAMPSON/
WAYNE COUNTIES. SOME UNCERTAINTY IS PRESENT...AND THE INSTABILITY
AXIS COULD BE SLIGHTLY FURTHER TO THE EAST OR WEST...DEPENDING ON
THE LOCATION OF THE SFC-H85 TROUGH. FORCING FOR ASCENT TODAY WILL
PRIMARILY BE ASSOCIATED WITH LOW-LEVEL CONVERGENCE IN VICINITY OF
THE SEABREEZE AND THE SFC-H85 TROUGH OVER THE COASTAL CAROLINAS.
SHORTWAVE ENERGY PROGRESSING INTO ILLINOIS AT 06Z WILL PROGRESS EAST
THROUGH THE MID-ATLANTIC THIS AFTERNOON...RESULTING IN WEAK DPVA
OVER NORTHERN PORTIONS OF THE STATE. WITH THE ABOVE IN MIND...WILL
INDICATE A 20-30% CHANCE OF SHOWERS/STORMS IN THE SOUTHEAST COASTAL
PLAIN CLOSER TO THE BEST MOISTURE/INSTABILITY AND LOW-LEVEL FORCING
DURING PEAK HEATING. ANTICIPATE THAT THE DRIER /MORE STABLE/ AIRMASS
IN PLACE OVER NORTHERN PORTIONS OF THE AREA WILL PRECLUDE A CHANCE
FOR CONVECTION WITH THE AFOREMENTIONED SHORTWAVE ENERGY. WILL KEEP
THE FORECAST DRY OVERNIGHT.
TEMPERATURES:
GIVEN LESS CLOUD COVER AND 1000-850 MB THICKNESSES SIMILAR TO
PREVIOUS DAYS...EXPECT HIGHS IN THE UPPER 80S TO 90-91F. LOWS
TONIGHT IN THE UPPER 60S TO LOWER 70S...WARMEST WHERE A LIGHT
SOUTHERLY BREEZE IS PRESENT AS THE MSLP GRADIENT BEGINS TO TIGHTEN
FROM THE WEST PRIOR TO SUNRISE. -VINCENT
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 303 AM FRIDAY...
...SLIGHT CHANCE OF SEVERE THUNDERSTORMS SATURDAY AFTERNOON AND
EARLY EVENING...
THE BIG PATTERN CHANGE THAT HAS BEEN ADVERTISED FOR DAYS WILL START
WITH A BANG SATURDAY AFTERNOON. A POSITIVELY TILTED MID-UPPER TROUGH
IS FORECAST TO AMPLIFY AS IT DIVES SE ACROSS THE CENTRAL
APPALACHIANS AND MID-ATLANTIC STATES SATURDAY AFTERNOON. THE
ASSOCIATED COLD FRONT WILL PUSH INTO THE REGION DURING PEAK HEATING.
THE THE MOST FAVORABLE WINDS ALOFT FOR ORGANIZED SEVERE STORMS MAY
REMAIN JUST TO OUR NORTH. HOWEVER... STRONG SURFACE HEATING IS
EXPECTED TO DESTABILIZE THE BOUNDARY LAYER BY EARLY AFTERNOON OUT
AHEAD OF A PRE-FRONTAL TROUGH/REMNANT CONVECTIVE OUTFLOW BOUNDARY.
THIS BOUNDARY SHOULD BEGIN TO ARRIVE DURING PEAK HEATING FOR MUCH OF
CENTRAL NORTH CAROLINA. WITH STRONG HEATING... TEMPERATURES SHOULD
REACH AROUND 90 BY EARLY AFTERNOON THROUGHOUT MOST OF THE REGION.
THIS WILL COMBINE WITH DEW POINTS FORECAST TO BE IN THE LOWER 70S TO
PRODUCE FAVORABLE PARAMETERS FOR MULTICELL STORM CLUSTERS. A FEW
OF THESE STORMS MAY BECOME SEVERE WITH THE MAIN THREAT BEING
DAMAGING WET DOWNBURSTS. THE MULTICELL CLUSTERS MAY EVOLVE INTO A
LINE BY LATE AFTERNOON AGAIN FAVORING ISOLATED DAMAGING WIND GUSTS
ALONG LEWP/BOWING SEGMENTS. THERE MAY BE A FINAL LINE OF CONVECTION
WITH THE MAIN COLD FRONT LATER IN THE DAY OR EVENING. REGARDLESS...
SATURDAY AFTERNOON AND EVENING IS EXPECTED TO BE ACTIVE ONCE AGAIN.
IN ADDITION TO THE SLIGHT CHANCE OF SEVERE STORMS... FREQUENT CG
LIGHTNING AND LOCALLY HEAVY RAIN IS AGAIN EXPECTED WITH THE STORMS.
EARLY MORNING STRATUS WILL GIVE WAY TO PARTLY SUNNY SKIES. WE WILL
CARRY LIKELY POP FOR SHOWERS AND THUNDERSTORMS IN THE AFTERNOON AND
EVENING. HIGHS 90-93 EXCEPT UPPER 80S NW.
THE STORMS WILL GRADUALLY END SATURDAY EVENING NW... AND ELSEWHERE
OVERNIGHT WITH THE ACTUAL COLD FRONTAL PASSAGE. GOOD DRY/COOL AIR
ADVECTION WILL ARRIVE MAINLY BETWEEN 06Z-12Z. THIS LATE CAA ARRIVAL
COMBINED WITH LINGER CLOUDS SHOULD KEEP LOWS MILD AND LIKELY ABOVE
GUIDANCE. WE WILL CARRY 60-65 MOST AREAS.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 303 AM FRIDAY...
A LONG AWAITED BREATHER FROM ALL THE VERY WARM/HUMID/THUNDERY
WEATHER WILL BEGIN SUNDAY. A REFRESHING BREEZE WILL COMBINE WITH
AMPLE SUNSHINE TO BRING A SPRING-LIKE FEEL. HIGHS OF 78-83 EXPECTED
(WITH DEW POINTS IN THE 40S NW AND LOWER 50S SE). A NORTHERLY BREEZE
AT 10-15 MPH WILL MAKE IT FEEL APRIL-FRESH AT TIMES.
MONDAY THROUGH THURSDAY...
EXPECT DRY AND SEASONABLY COOL CONDITIONS MONDAY AND TUESDAY... WITH
MODERATING DAYTIME TEMPS WED AND THUR. MOSTLY CLEAR/MOSTLY SUNNY
WITH LOWS IN THE 50S EACH DAY. HIGHS 75 TO 80 MON-TUE... WARMING
INTO THE LOWER TO MID 80S BY THURSDAY.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 155 AM FRIDAY...
24-HR TAF PERIOD:
IFR TO VLIFR CEILINGS AND VISBYS ARE PRESENT OVER PORTIONS OF THE
NORTHERN PIEDMONT (INCLUDING RDU/RWI) AS OF 06Z. GIVEN A VERY MOIST
LOW-LEVEL AIRMASS...LIGHT/CALM WINDS...AND A DRIER MID-LEVEL AIRMASS
PROGRESSING INTO THE AREA FROM THE NORTHWEST...EXPECT THAT ALL TAF
SITES WILL SEE CONDITIONS DETERIORATE INTO THE IFR TO VLIFR RANGE
BETWEEN 06-12Z THIS MORNING. FOG AND LOW CEILINGS ARE EXPECTED TO
LIFT AND SCATTER TO VFR BETWEEN 12-15Z AT INT/GSO/RDU. CONDITIONS
SHOULD BE SLOWER TO IMPROVE AT THE FAY/RWI TERMINALS WHERE MOISTURE
IS DEEPER AND MVFR CEILINGS MAY PERSIST THROUGH ~18Z. ISOLATED
SHOWERS AND STORMS WILL BE POSSIBLE DURING THE AFTERNOON...THOUGH
CHANCES WILL MOST LIKELY BE LIMITED TO THE FAY TERMINAL.
OTHERWISE...EXPECT VFR CONDITIONS TO PREVAIL THIS AFTERNOON THROUGH
06Z TONIGHT. LOW-LEVEL SOUTHERLY FLOW WILL STRENGTHEN PRIOR TO
SUNRISE SATURDAY IN ADVANCE OF AN APPROACHING COLD FRONT...AND IT IS
POSSIBLE THAT MVFR/IFR CEILINGS MAY DEVELOP BETWEEN 09-12Z SAT.
LOOKING AHEAD:
A STRONG COLD FRONT WILL TRACK EAST INTO CENTRAL NC SATURDAY
AFT/EVE. A LINE OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ALONG
AND AHEAD OF THE FRONT. RAIN MAY LINGER INTO SATURDAY NIGHT AND
EARLY SUNDAY MORNING IN THE WAKE OF THE FRONTAL PASSAGE...PRIMARILY
AT THE FAY/RWI TERMINALS. VFR CONDITIONS WILL RULE IN THE WAKE OF
THE COLD FRONT SUNDAY THROUGH EARLY NEXT WEEK AS COOL AND DRY HIGH
PRESSURE BUILDS INTO THE CAROLINAS. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM....VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
647 AM EDT FRI SEP 7 2012
.SYNOPSIS...
HIGH PRESSURE TODAY PROVIDING HOT AND MOSTLY DRY WEATHER. STRONG
COLD FRONT SATURDAY. HIGH PRESSURE SUNDAY INTO EARLY NEXT WEEK
BRINGING MUCH COOLER WEATHER.
&&
.NEAR TERM /THROUGH TONIGHT/...
630 AM UPDATE...NO SIGNIFICANT CHANGES MADE TO FORECAST. HOWEVER THERE
IS AT LEAST SOME GROWING POTENTIAL FOR A FEW ISOLATED SHOWERS/STORMS
ACROSS THE FAR NW ZONES DURING THE LATE AFTERNOON/EARLY EVE IN SE
OHIO WHERE A BIT MORE LLVL MOISTURE WILL RESIDE AROUND THE 850MB
LEVEL UNCAPPED PER LATEST NAM AND RUC SOUNDINGS. WILL PASS THIS
ALONG TO DAYSHIFT FOR MONITORING.
PREVIOUS DISCUSSION...
PRIMARY CONCERN FOR THIS FORECAST PERIOD CONTINUES TO BE THE
APPROACHING COLD FRONT DURING THE OVERNIGHT HOURS. TODAY...SOME
EARLY MORNING CLOUDS MAINLY ACROSS THE NORTHERN AND EASTERN ZONES
SHOULD DISSIPATE. FORECAST AREA WILL TRANSITION FROM A ZONAL FLOW
TO SOUTHWESTERLY FLOW AS VIGOROUS UPPER LEVEL TROUGH DIVES
SOUTHEASTWARD ACROSS THE WESTERN GREAT LAKES REGION. BEST FLOW
REMAINS WELL TO THE WEST OF THE FORECAST AREA PRIOR TO 00Z SAT.
BOTH FINER RESOLUTION NAM/GFS DEPICT AN AREA OF INCREASED
850-700MB MOISTURE OVER THE HIGHER TERRAIN OF RANDOLPH/POCAHONTAS
COUNTIES ALONG WITH SFC CONVERGENCE IN THOSE AREAS. AM SOMEWHAT
SUSPICIOUS OF THIS DEPICTION BUT WILL GO AHEAD AND INTRODUCE
SLIGHT POPS FOR A FEW HOURS ACROSS THOSE FAR EASTERN COUNTIES
MAINLY BETWEEN 19Z-00Z DURING MAX HEATING. INHERITED MAX TEMPS
AROUND 90 DEGREES STILL LOOK GOOD AND HAVE ONLY MADE MINOR
ADJUSTMENTS.
DURING THE EVENING AND OVERNIGHT HOURS THE TROUGH AND COLD FRONT
CONTINUE MOVING TOWARDS THE FORECAST AREA. BOTH THE LATEST NAM AND
GFS SLOW THE SYSTEM/S PROGRESSION AS WELL AS DEEPEN THE LOW
ITSELF...WITH THE AXIS PROGGED TO BE ROUGHLY ACROSS NW INDIANA AND
THE SFC COLD FRONT JUST NEARING/ENTERING THE FAR NW ZONES BY 12Z.
WILL SLOW THE ONSET OF POPS DOWN BY A FEW HOURS BUT WITH GOOD DEPTH
OF LLVL MOISTURE INCREASING RAPIDLY ACROSS THE WESTERN ZONES BY 09Z
AND A VORT MAX PROGGED TO LOCATED ACROSS CENTRAL KY BY 06Z MOVING
NE-WARD...STILL THINK SHOWERS AND THUNDERSTORMS A GOOD BET BY 09Z
MAINLY ALONG AND WEST OF THE OHIO RIVER...WITH PERHAPS A SMALL GAP
BETWEEN THIS AREA OF PRECIP AND THE PRECIP ASSOC WITH THE FRONT
ITSELF.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
STRONG UPPER TROUGH AND ASSOCIATED COLD FRONT WILL SWEEP ACROSS THE
AREA SATURDAY. MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE TIMING
OF THIS FRONT. THE NAM SEEMS A LITTLE BIT FASTER CONTRARY TO THE
ECMWF/GFS/CMC MODELS. ADJUSTED PREVIOUS CATEGORICAL POPS AND WINDS
DELAYING THE WIND SHIFT AND ONSET OF PCPN ABOUT 3 HOURS. STRONG H5
VORTICITY ADVECTION PROVIDE STRONG OMEGA AT H5-H7 LAYER...AS WELL AS
DESCENT UPPER LEVEL JET DIVERGENCE WORKING OVER PWATS AROUND 2
INCHES AND A H7-H85 THETA-E RIDGE. THEREFORE...PREVIOUS FORECAST HAD
A GOOD HANDLE ON CATEGORICAL POPS AND MINOR ADJUSTMENTS WERE
REQUIRED. DRIER AIR BEHIND THE FRONT WILL BRING COOLER TEMPS
SATURDAY NIGHT...AND PUSH PCPN OVER THE EASTERN MOUNTAINS BY 00Z
SUNDAY. HOWEVER...KEPT LOW CHANCE POPS FOR LINGERING STRATIFORM PCPN
THRU AT LEAST 06 SUNDAY OVER THE MOUNTAINS.
ANOTHER BUT UPPER LEVEL TROUGH MOVES THRU ON SUNDAY...WITH LESS
MOISTURE AVAILABLE. THERE COULD BE ENOUGH MOISTURE TO PRODUCE FEW
SHOWERS OR STORMS MAINLY ACROSS THE NORTHERN PORTIONS OF WV.
THEREFORE...ADDED LOW CHANCE POPS FOR NOW. AT LEAST EXPECT CLOUDS
MOVING THROUGH WITH FEW SHOWERS.
WITH CLOUDS...AND THEN THE COOLER AIRMASS BEHIND THE COLD
FRONT...KEPT AFTERNOON HIGHS IN THE 60S AND 70S THIS WEEKEND.
FRIDAY NIGHT WILL BE WARM AS CLOUDS AND MOISTURE INCREASE...WITH A
MUCH COOLER NIGHT SATURDAY INTO SUNDAY.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
OVERALL A DRY PATTERN EXPECTED FOR THE LONG TERM...WITH UPPER LEVEL
RIDGE BUILDING OVER THE SOUTHERN PLAINS...AND SLIDING EAST INTO THE
SE UNITED STATES BY MID WEEK. BOTH GFS AND ECMWF SHOWING AN UPPER
LOW MOVING TOWARDS HUDSON BAY LATE NEXT WEEK. ECMWF A BIT
FASTER...BUT ALSO KEEPS THE ENERGY FARTHER NORTH...WHILE GFS DOES
NOT SHOW THE TROUGH IMPACTING FORECAST AREA UNTIL AFTER LONG TERM
PERIOD...SO WILL KEEP THINGS DRY ALL WEEK.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
EARLY MORNING FOG AND LOW STRATUS WILL BURN OFF/SCATTER SHORTLY
AFTER SUNRISE. VFR CONDITIONS WILL PREVAIL FOR MUCH OF THE REMAINDER
OF VALID PERIOD WITH SURFACE FLOW OUT OF THE SOUTHWEST. DURING
THE EVENING HOURS PREDOMINATELY HIGH AND MID LEVEL CLOUDS WILL
INCREASE IN ADVANCE OF AN APPROACHING COLD FRONT...WITH AN INCREASING
CHANCE OF SHOWERS AND THUNDERSTORMS NEAR THE END OF THE PERIOD
MAINLY BETWEEN 09Z-12Z ALONG AND WEST OF THE OHIO RIVER...WITH
POTENTIAL REDUCTION IN VIS IN STRONGER SHOWERS/STORMS. ABUNDANT CLOUD
COVER AND STRONGER WINDS AT AND ABOVE SURFACE SHOULD PRECLUDE WIDESPREAD
FOG DEVELOPMENT.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z SATURDAY...
FORECAST CONFIDENCE: HIGH.
ALTERNATE SCENARIOS: DISSIPATION OF FOG AND LOW STRATUS MAY VARY
BY AN HOUR OR TWO.
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 L L M H H H H H H H H H
HTS CONSISTENCY L L M H H H H H H H H H
BKW CONSISTENCY L H H H H H H H H H H H
EKN CONSISTENCY L L H H H H H H H H H H
PKB CONSISTENCY L L H H H H H H H H H H
CKB CONSISTENCY L L M H H H H H H H H H
AFTER 12Z SATURDAY...
IFR POSSIBLE IN SHOWERS AND THUNDERSTORMS SATURDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...ARJ/50
NEAR TERM...50
SHORT TERM...ARJ
LONG TERM...MZ
AVIATION...50
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
148 AM EDT FRI SEP 7 2012
.SYNOPSIS...
A WEAK DISTURBANCE WILL BRING A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS TO NORTHERN PORTIONS OF THE AREA TODAY. HIGH
PRESSURE WILL WORK INTO THE AREA TONIGHT AND REMAIN ACROSS THE
AREA THROUGH FRIDAY MORNING. A LOW PRESSURE SYSTEM...AND A STRONG
COLD FRONT...WILL BRING PRECIPITATION BACK TO THE AREA FROM FRIDAY
AFTERNOON THROUGH SATURDAY MORNING.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
ISOLATED SHOWERS AND THUNDERSTORMS CONTINUE NEAR A WEAK FRONTAL
BOUNDARY ACROSS THE NORTHERN PORTIONS OF THE FORECAST AREA. HAVE
EXTENDED SLIGHT CHANCE POPS UNTIL MIDNIGHT FOR PORTIONS OF THE
AREA. THE LATEST HRRR INDICATES THAT SOME OF THIS ACTIVITY MAY
TRY TO REDEVELOP FARTHER SOUTH...LIKELY OUTFLOW INITIATED...WHERE
THE BETTER ELEVATED INSTABILITY IS LOCATED. HOWEVER...KEPT THESE
ZONES DRY FOR NOW.
IN THE SOUTH...SURFACE DEWPOINTS IN THE UPPER 60S WILL ALLOW FOR
SOME FOG TO DEVELOP...BUT NOT LIKELY AS WIDESPREAD AS THE PAST
TWO NIGHTS. HAVE LIMITED THE MENTION OF FOG IN THE ZONES MAINLY TO
VALLEY LOCATIONS ACROSS THE SOUTHERN HALF OF THE FORECAST AREA.
ACROSS THE NORTH...SLIGHTLY DRIER CONDITIONS AND A MORE CLOUDY
START TO THE OVERNIGHT PERIOD SHOULD LIMIT FOG DEVELOPMENT.
MINIMUM TEMPERATURES WERE NOT ADJUSTED ON THIS UPDATE AS EVENTUAL
LATE NIGHT CLEARING ACROSS THE NORTH WILL ALLOW FOR TEMPERATURES
TO DROP INTO THE LOW 60S. SOUTH OF THE FRONT...TEMPERATURES WILL
REMAIN IN THE UPPER 60S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
SURFACE LOW PRESSURE IS EXPECTED TO DEVELOP OVER NORTHERN
ILLINOIS ON FRIDAY AFTERNOON. THIS LOW WILL MOVE QUICKLY TO THE
ENE AS IT DEEPENS...AND ROUNDS THE FRONT EDGE OF A VERY SHARP MID
LEVEL TROUGH OVER THE GREAT LAKES. A STRONG COLD FRONT WILL TRAIL
SOUTHWEST FROM THIS LOW PRESSURE CENTER...MOVING EAST THROUGH THE
OHIO VALLEY THROUGH SATURDAY MORNING.
FRONTAL TIMING IS IN DECENT AGREEMENT BETWEEN THE
MODELS...ALTHOUGH BY THE END OF ITS PASSAGE...THE SURFACE LOW
POSITION AND STRENGTH ARE HANDLED SLIGHTLY DIFFERENTLY. DESPITE
THE DIFFERING POSITIONS OF THE SURFACE LOW (WHICH WILL NOT
DIRECTLY IMPACT THE ILN CWA)...THE RIBBON OF DEEP MOISTURE
AND EXPECTED PRECIPITATION SEEM TO BE WITHIN 3 HOURS OF EACH OTHER
EVEN BY SATURDAY AFTERNOON. THIS HAS LED TO A VERY DETERMINISTIC
POP/WX FORECAST...WITH A 100 PERCENT CHANCE OF TS/RA THAT SPREAD
ACROSS THE ENTIRE FORECAST AREA. FORCING WILL NOT BE IN QUESTION
WITH THIS SYSTEM...WITH PLENTY OF SUPPORT FROM THE COLD FRONT AND
UPPER TROUGH.
THE POTENTIAL FOR HAZARDOUS WEATHER WITH THIS SYSTEM IS THE
PRIMARY CONCERN OF THE SHORT TERM FORECAST. THE FRONT WILL BE
MOVING INTO AN ENVIRONMENT WITH 30-40 KNOTS OF 0-6KM SHEAR...AND
15-25 KNOTS IN THE LOWEST KILOMETER OR TWO. MLCAPE DURING PEAK
HEATING WILL BE IN THE 1500-2000 J/KG RANGE. GIVEN THE STRONG
FORCING...THESE PARAMETERS CERTAINLY SUPPORT A SEVERE WEATHER
THREAT. THE BIGGEST NEGATIVE FOR SEVERE POTENTIAL IS THE
TIMING...SINCE MUCH OF THE ACTIVITY IS EXPECTED TO TAKE PLACE
AFTER 00Z. THERE IS NO BIG PUSH OF MOISTURE IN THE BOUNDARY
LAYER...WITH THE HIGHEST DEWPOINTS BEING RELEGATED TO A RIBBON
ALONG AND NEAR THE FRONT. WANING INSTABILITY AFTER SUNSET (A
FACTOR PARTIALLY CONNECTED TO THE ABOVE) WILL LIMIT THE STRENGTH
OF THE CONVECTION. IN ADDITION...THE FRONT IS EXPECTED TO BE
FORWARD PROPAGATING AT AROUND 30 MPH...NOT FAST ENOUGH TO KEEP UP
WITH THE MOVEMENT OF INDIVIDUAL STORM CELLS OR LINES (OR THEIR
OUTFLOW BOUNDARIES).
THE END RESULT IS THAT A LINE (OR BROKEN LINE) OF STRONG TO SEVERE
CONVECTION IS EXPECTED TO MOVE INTO THE ILN CWA LATE TOMORROW
AFTERNOON. THE GREATER THREAT IS IN THE WESTERN HALF OF THE
CWA...WITH A PROJECTED WEAKENING TREND IN THE CONVECTION DURING
THE EVENING AND OVERNIGHT HOURS. DAMAGING WINDS WILL BE THE
PRIMARY THREAT...WITH SOME LARGE HAIL ALSO POSSIBLE. THE LOW LEVEL
SHEAR WILL SUPPORT SOME POSSIBILITY OF TORNADOES BEFORE THE
BOUNDARY LAYER BEGINS TO DECOUPLE...THOUGH THIS THREAT WOULD
LIKELY BE TIED TO THE EVOLUTION OF THE INDIVIDUAL QLCS ELEMENTS
WITHIN THE CONVECTION. HEAVY RAIN IS ALSO A POSSIBILITY. ALTHOUGH
WIDESPREAD QPF TOTALS WILL PROBABLY BE IN THE 0.75-1.25 INCH
RANGE...PWATS NEAR TWO INCHES AND MOISTURE TRANSPORT THAT
PARALLELS THE FRONT WILL RESULT IN SOME POSSIBILITY OF TRAINING
AND POTENTIAL LOCALIZED FLOODING.
THE FRONT DOES SLOW DOWN SOMEWHAT AS IT MOVES INTO THE UPPER OHIO
VALLEY...AS ITS ORIENTATION BECOMES MORE SSW/NNE AND THE SURFACE
LOW ALSO GAINS MORE OF A NORTHERLY COMPONENT TO ITS MOTION.
EVEN STILL...THE SYSTEM IS LARGELY A PROGRESSIVE ONE. THIS
FORECAST PACKAGE WILL BE SLIGHTLY AGGRESSIVE IN CLEARING POPS OUT
BEHIND THE FRONT...WITH THE EXPECTATION THAT MOST OF THE WESTERN
HALF OF THE CWA WILL HAVE A DRY SATURDAY. HOWEVER...SOME LOW LEVEL
MOISTURE BEHIND THE FRONT WILL KEEP CLOUDS AROUND FOR A WHILE.
ESPECIALLY GIVEN THE COLD ADVECTION PROVIDED BY THE FRONT...A
SIGNIFICANT COOL DOWN IS EXPECTED...WITH HIGHS ONLY REACHING THE
LOWER 70S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
SHORT WAVE ENERGY WILL ROTATE DOWN ACROSS THE GREAT LAKES SATURDAY
NIGHT INTO SUNDAY. MOISTURE IS PRETTY LIMITED...BUT THE COMBINATION
OF THIS AND SOME DAYTIME HEATING...MAY BE ENOUGH TO SQUEEZE OUT A
FEW SHOWERS OR SPRINKLES ACROSS OUR NORTH SUNDAY AFTERNOON.
OTHERWISE...RIDGING AT THE SURFACE AND ALOFT WILL BUILD INTO THE
AREA THROUGH TUESDAY BEFORE SHIFTING OFF TO THE EAST THROUGH THE END
OF THE LONG TERM PERIOD. THIS WILL PROVIDE DRY CONDITIONS AND MAINLY
CLEAR SKIES THROUGH AT LEAST MID WEEK. AS THE SURFACE HIGH SLIDES
OVERHEAD...CLEAR SKIES AND LIGHT WINDS WILL LEAD TO SOME SEASONABLY
COOL NIGHTS. EXPECT OVERNIGHT LOWS TO DIP DOWN INTO THE 40S IN SOME
OF THE OUTLYING AREAS THROUGH THE FIRST PART OF THE WEEK WITH
DAYTIME HIGHS GENERALLY IN THE 70S. WE WILL THEN SEE A GRADUAL
MODERATION IN TEMPS WEDNESDAY INTO THURSDAY AS THE HIGH BEGINS TO
PUSH OFF TO THE EAST AND WE GET INTO RETURN FLOW.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
TIMING OF THE INITIAL LINE OF SHOWERS AND THUNDERSTORMS APPEARS
TO KEEP BEING PUSHED BACK WITH EACH MODEL AND SUCCESSIVE RUN. DO
NOT EXPECT ANY WX AT TAF SITES THROUGH 0Z...EVEN THOUGH SOME WARM
SECTOR SHOWERS AHEAD OF THE FRONT WILL LIKELY OCCUR. PREVAILING
RAINFALL WILL BE AT A MAXIMUM IN THE 4-8Z TIME FRAME AND TRAIL OFF
AFTER THIS. WIND SHIFT WITH FROPA MAY SEE SOME GUSTS APPROACHING
30KTS...BUT THIS IS BEYOND THE FIRST 24 HOURS COVERED IN TAFS.
.OUTLOOK...MVFR CIGS AND VSBYS ARE POSSIBLE IN SHOWERS SATURDAY
MORNING.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...LATTO
SHORT TERM...HATZOS
LONG TERM...JGL
AVIATION...FRANKS
AREA FORECAST DISCUSSION
NWS TULSA OK
320 PM CDT FRI SEP 7 2012
.DISCUSSION...
CHANGES ARE A COMING. THE SURFACE COLD FRONT...WHICH WAS HELD UP
FOR A TIME TODAY AS A WEAK LOW PRESSURE RIPPLED ON BY...IS NOW ON
THE MOVE. WIND GUSTS ARE TOPPING 50 MPH BEHIND THE FRONT...DUE TO
THE TIGHT PRESSURE GRADIENT AND ISALLOBARIC FORCING. AS THIS
FRONT MOVES SOUTH THE POTENTIAL FOR STRONG WIND GUSTS IN EXCESS OF
40 MPH WILL LIKELY CONTINUE...MAINLY ACROSS NORTHEAST OK. WILL LET
THE ONGOING WIND ADVISORY CONTINUE THRU 03Z AND LET THE EVENING
SHIFT ADJUST IF NEED BE. AHEAD OF THE FRONT...TEMPS HAVE SOARED
ONCE THE MID CLOUDS CLEARED OUT ENOUGH TO ALLOW FOR SOME
INSOLATION. BRISTOW MESONET HAS HIT 108 DEGREES. MUCH OF EASTERN
OK IN FACT IS ABOVE 100 DEGREES THIS HOUR. WILL LET THE HEAT
HEADLINES CONTINUE THROUGH 00Z...AND WE WILL FINALLY BE ABLE TO
SHELVE THIS FOR AWHILE BY TONIGHT.
PRECIP CHANCES WILL BE A CHALLENGE...ESPECIALLY FOR WESTERN
SECTIONS. THE HRRR SUGGESTS THAT CONVECTION WILL GRADUALLY
INCREASE IN COVERAGE IN THE VICINITY OF THE FRONT THIS
AFTERNOON...EVENTUALLY ORGANIZING INTO LINE SEGMENTS OR CLUSTERS
AS THEY MOVE INTO FAR EASTERN OK AND WESTERN AR THIS EVENING. THE
LATEST ECMWF ALSO SUGGESTS A BAND OF POST FRONTAL CONVECTION WILL
DEVELOP LATER ON TONIGHT...AS STRONG MID LVL COLD FRONTOGENESIS
AND QG FORCING FOR ASCENT INCREASES AS THE MAIN SHORTWAVE
APPROACHES. I HAVE ADJUSTED POPS UPWARD ACROSS NORTHEAST OK IN
ANTICIPATION OF THIS. GIVEN THE INSTABILITY AND GRADUALLY
INCREASING SHEAR WITH TIME...SEVERE WIND AND HAIL ARE A GOOD
POSSIBILITY...ESPECIALLY IF AN ORGANIZED LINE SEGMENT OR CLUSTER
CAN GET GOING IN THE HOT WARM SECTOR. PRECIP CHANCES WILL QUICKLY
SHIFT SOUTHEAST AFTER 06Z AND SHOULD BE DONE BY 12Z WITH SKIES
CLEARING OUT.
SHOULD BE A VERY NICE WEEKEND WITH HIGHS IN THE 80S AND LOWS IN
THE 50S...EVEN UPPER 40S BY SUNDAY MORNING OVER PARTS OF NW AR. A
BACK DOOR FRONT WILL ATTEMPT TO KEEP THE WARMING TREND IN CHECK
OVER NE OK AND NW AR SUNDAY AFTERNOON. TEMPS WILL WARM BACK INTO
THE 90S EARLY NEXT WEEK WITH SHORTWAVE RIDGING OVERHEAD. A FRONTAL
BOUNDARY WILL EVENTUALLY PUSH INTO THE REGION BY FRIDAY OF NEXT
WEEK...AND THERE IS REASONABLE ENOUGH AGREEMENT BETWEEN THE MEDIUM
RANGE MODELS TO INSERT A SLIGHT CHANCE FOR THE TAIL END OF THE
FORECAST.
LACY
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 55 80 53 88 / 60 0 0 0
FSM 61 81 54 88 / 60 0 0 0
MLC 60 81 54 89 / 40 0 0 0
BVO 54 81 51 88 / 50 0 0 0
FYV 55 76 48 84 / 80 0 0 0
BYV 54 75 49 81 / 80 0 0 0
MKO 57 80 53 86 / 60 0 0 0
MIO 55 78 53 82 / 70 0 0 0
F10 58 80 56 87 / 50 0 0 0
HHW 63 82 55 87 / 30 0 0 0
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...EXCESSIVE HEAT WARNING UNTIL 7 PM FRIDAY FOR OKZ053.
HEAT ADVISORY UNTIL 7 PM FRIDAY FOR OKZ049-OKZ060-OKZ064-OKZ065-
OKZ066-OKZ067-OKZ068-OKZ070-OKZ071-OKZ072-OKZ073-OKZ074-
OKZ075-OKZ076.
WIND ADVISORY UNTIL 10 PM FRIDAY FOR OKZ054-OKZ055-OKZ056-OKZ057-
OKZ058-OKZ059-OKZ060-OKZ061-OKZ062-OKZ063-OKZ064-OKZ065-
OKZ066-OKZ067.
AR...HEAT ADVISORY UNTIL 7 PM FRIDAY FOR ARZ019-ARZ020.
EXCESSIVE HEAT WARNING UNTIL 7 PM FRIDAY FOR ARZ029.
&&
$$
LONG TERM....30
AREA FORECAST DISCUSSION
NWS NORMAN OK
1234 PM CDT FRI SEP 7 2012
.AVIATION...
18Z TAFS... STRONG COLD FRONT WILL CONTINUE TO MOVE ACROSS THE
REGION WITH GUSTY WINDS BEHIND THE FRONT. ISOLATED/SCATTERED
SHOWERS/STORMS WILL BE POSSIBLE MAINLY ALONG AND BEHIND THE FRONT
THIS AFTERNOON AND TONIGHT. CHANCES ARE TOO LOW AT TIMES FOR
MENTION IN TAFS. CEILINGS WILL BE MOSTLY VFR... BUT LOW VFR.
&&
.PREV DISCUSSION... /ISSUED 633 AM CDT FRI SEP 7 2012/
AVIATION...
07/12Z TAFS...VFR CONDITIONS EXPECTED. SCATTERED TSRA COULD AFFECT
MAINLY KPNC DOWN TOWARD KOKC ALONG AND BEHIND STRONG FRONT THAT
WILL SURGE SOUTHWARD TODAY. VERY LITTLE IF ANY COLD FRONT TIMING
CHANGES MADE FROM PREVIOUS FORECAST CYCLE. OUTSIDE OF POSSIBILITY
FOR TSRA FOR A FEW HOURS LATE THIS AFTERNOON AND THIS EVENING...
MAIN IMPACTS TO TERMINALS WILL BE STRONG NORTHERLY WIND WITH GUSTS
AOA 40KT SEVERAL HOURS FOLLOWING FROPA.
PREV DISCUSSION... /ISSUED 437 AM CDT FRI SEP 7 2012/
DISCUSSION...
BIG CHANGES WILL BE SEEN THIS AFTERNOON AND EVENING...BUT BEFORE
THE FRONT ARRIVES IT WILL BE QUITE HOT WITH FAIRLY SUBSTANTIAL
PRE-FRONTAL THERMAL RIDGE IN PLACE. FIRST PERIOD OF FORECAST WILL
CLOSELY RESEMBLE WRF SOLUTIONS OF THE PAST COUPLE OF RUNS. HOTTER
AHEAD OF FRONT AND MORE SUBSTANTIAL CAA/WIND BEHIND IT. WE WILL
ISSUE A WIND ADVISORY FOR THIS AFTERNOON AND EVENING. FREQUENT
GUSTS AROUND 45 MPH NOT OUT OF THE QUESTION FOR AT LEAST 2 TO 4
HOURS AFTER FROPA COINCIDING WITH STRONG CAA. SOME OF THE WINDIER
SPOTS OF W/SW OKLAHOMA COULD SEE SOME GUSTS IN EXCESS OF 50 MPH.
AS FAR AS THE CHANGE IN TEMPERATURE GOES...WE EXPECT TEMPS TO FALL
20 TO 30 DEGREES IN JUST A FEW HOURS AFTER FRONTAL PASSAGE...
ESPECIALLY ACROSS CENTRAL AND SOUTHERN PORTIONS OF OKLAHOMA AND
NORTH TEXAS WHERE TEMPS EXPECTED TO APPROACH OR EXCEED 100 AHEAD
OF FRONT. AS FAR AS POPS GO...COULD SEE SOME ISOLATED SHOWERS OR
STORMS ACROSS NORTH-CENTRAL AND PERHAPS CENTRAL OKLAHOMA EARLY
THIS MORNING...WITH THE HRRR BEING THE MOST AGGRESSIVE WITH THIS
POTENTIAL. SCATTERED STORMS MAY FORM ALONG FRONT THIS AFTERNOON
BUT BEST CHANCES FOR RAIN APPEAR TO BE THIS EVENING BEHIND THE
FRONT AS MAIN MID-LEVEL TROUGH AXIS MOVES INTO THE REGION.
SEASONABLY COOL WEEKEND IN STORE BEFORE TEMPS BEGIN TO INCREASE
AHEAD OF NEXT FRONTAL BOUNDARY WHICH MEDIUM RANGE MODELS WANT TO
BRING TOWARD THE END OF NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 99 57 83 54 / 30 40 0 0
HOBART OK 99 55 85 54 / 20 30 0 0
WICHITA FALLS TX 104 59 86 56 / 20 30 0 0
GAGE OK 88 53 83 49 / 20 10 0 0
PONCA CITY OK 93 53 82 54 / 40 20 0 0
DURANT OK 102 60 84 53 / 10 30 0 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...WIND ADVISORY FROM 4 PM THIS AFTERNOON TO 10 PM CDT THIS EVENING
FOR OKZ007-008-012-013-016>026-033>036.
WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR OKZ004>006-009>011-
014-015.
WIND ADVISORY FROM 6 PM TO 10 PM CDT THIS EVENING FOR OKZ027>031-
037>040-044-045.
TX...WIND ADVISORY FROM 6 PM TO 10 PM CDT THIS EVENING FOR TXZ083>090.
&&
$$
26/25/25
AREA FORECAST DISCUSSION
NWS NORMAN OK
633 AM CDT FRI SEP 7 2012
.AVIATION...
07/12Z TAFS...VFR CONDITIONS EXPECTED. SCATTERED TSRA COULD AFFECT
MAINLY KPNC DOWN TOWARD KOKC ALONG AND BEHIND STRONG FRONT THAT
WILL SURGE SOUTHWARD TODAY. VERY LITTLE IF ANY COLD FRONT TIMING
CHANGES MADE FROM PREVIOUS FORECAST CYCLE. OUTSIDE OF POSSIBILITY
FOR TSRA FOR A FEW HOURS LATE THIS AFTERNOON AND THIS EVENING...
MAIN IMPACTS TO TERMINALS WILL BE STRONG NORTHERLY WIND WITH GUSTS
AOA 40KT SEVERAL HOURS FOLLOWING FROPA.
&&
.PREV DISCUSSION... /ISSUED 437 AM CDT FRI SEP 7 2012/
DISCUSSION...
BIG CHANGES WILL BE SEEN THIS AFTERNOON AND EVENING...BUT BEFORE
THE FRONT ARRIVES IT WILL BE QUITE HOT WITH FAIRLY SUBSTANTIAL
PRE-FRONTAL THERMAL RIDGE IN PLACE. FIRST PERIOD OF FORECAST WILL
CLOSELY RESEMBLE WRF SOLUTIONS OF THE PAST COUPLE OF RUNS. HOTTER
AHEAD OF FRONT AND MORE SUBSTANTIAL CAA/WIND BEHIND IT. WE WILL
ISSUE A WIND ADVISORY FOR THIS AFTERNOON AND EVENING. FREQUENT
GUSTS AROUND 45 MPH NOT OUT OF THE QUESTION FOR AT LEAST 2 TO 4
HOURS AFTER FROPA COINCIDING WITH STRONG CAA. SOME OF THE WINDIER
SPOTS OF W/SW OKLAHOMA COULD SEE SOME GUSTS IN EXCESS OF 50 MPH.
AS FAR AS THE CHANGE IN TEMPERATURE GOES...WE EXPECT TEMPS TO FALL
20 TO 30 DEGREES IN JUST A FEW HOURS AFTER FRONTAL PASSAGE...
ESPECIALLY ACROSS CENTRAL AND SOUTHERN PORTIONS OF OKLAHOMA AND
NORTH TEXAS WHERE TEMPS EXPECTED TO APPROACH OR EXCEED 100 AHEAD
OF FRONT. AS FAR AS POPS GO...COULD SEE SOME ISOLATED SHOWERS OR
STORMS ACROSS NORTH-CENTRAL AND PERHAPS CENTRAL OKLAHOMA EARLY
THIS MORNING...WITH THE HRRR BEING THE MOST AGGRESSIVE WITH THIS
POTENTIAL. SCATTERED STORMS MAY FORM ALONG FRONT THIS AFTERNOON
BUT BEST CHANCES FOR RAIN APPEAR TO BE THIS EVENING BEHIND THE
FRONT AS MAIN MID-LEVEL TROUGH AXIS MOVES INTO THE REGION.
SEASONABLY COOL WEEKEND IN STORE BEFORE TEMPS BEGIN TO INCREASE
AHEAD OF NEXT FRONTAL BOUNDARY WHICH MEDIUM RANGE MODELS WANT TO
BRING TOWARD THE END OF NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 99 57 83 54 / 30 40 0 0
HOBART OK 99 55 85 54 / 20 30 0 0
WICHITA FALLS TX 104 59 86 56 / 20 30 0 0
GAGE OK 88 53 83 49 / 20 10 0 0
PONCA CITY OK 93 53 82 54 / 40 20 0 0
DURANT OK 102 60 84 53 / 10 30 0 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...WIND ADVISORY FROM 4 PM THIS AFTERNOON TO 10 PM CDT THIS EVENING
FOR OKZ007-008-012-013-016>026-033>036.
WIND ADVISORY FROM NOON TODAY TO 6 PM CDT THIS EVENING FOR
OKZ004>006-009>011-014-015.
WIND ADVISORY FROM 6 PM TO 10 PM CDT THIS EVENING FOR OKZ027>031-
037>040-044-045.
TX...WIND ADVISORY FROM 6 PM TO 10 PM CDT THIS EVENING FOR TXZ083>090.
&&
$$
06/11/11
AREA FORECAST DISCUSSION
NWS NORMAN OK
437 AM CDT FRI SEP 7 2012
.DISCUSSION...
BIG CHANGES WILL BE SEEN THIS AFTERNOON AND EVENING...BUT BEFORE
THE FRONT ARRIVES IT WILL BE QUITE HOT WITH FAIRLY SUBSTANTIAL
PRE-FRONTAL THERMAL RIDGE IN PLACE. FIRST PERIOD OF FORECAST WILL
CLOSELY RESEMBLE WRF SOLUTIONS OF THE PAST COUPLE OF RUNS. HOTTER
AHEAD OF FRONT AND MORE SUBSTANTIAL CAA/WIND BEHIND IT. WE WILL
ISSUE A WIND ADVISORY FOR THIS AFTERNOON AND EVENING. FREQUENT
GUSTS AROUND 45 MPH NOT OUT OF THE QUESTION FOR AT LEAST 2 TO 4
HOURS AFTER FROPA COINCIDING WITH STRONG CAA. SOME OF THE WINDIER
SPOTS OF W/SW OKLAHOMA COULD SEE SOME GUSTS IN EXCESS OF 50 MPH.
AS FAR AS THE CHANGE IN TEMPERATURE GOES...WE EXPECT TEMPS TO FALL
20 TO 30 DEGREES IN JUST A FEW HOURS AFTER FRONTAL PASSAGE...
ESPECIALLY ACROSS CENTRAL AND SOUTHERN PORTIONS OF OKLAHOMA AND
NORTH TEXAS WHERE TEMPS EXPECTED TO APPROACH OR EXCEED 100 AHEAD
OF FRONT. AS FAR AS POPS GO...COULD SEE SOME ISOLATED SHOWERS OR
STORMS ACROSS NORTH-CENTRAL AND PERHAPS CENTRAL OKLAHOMA EARLY
THIS MORNING...WITH THE HRRR BEING THE MOST AGGRESSIVE WITH THIS
POTENTIAL. SCATTERED STORMS MAY FORM ALONG FRONT THIS AFTERNOON
BUT BEST CHANCES FOR RAIN APPEAR TO BE THIS EVENING BEHIND THE
FRONT AS MAIN MID-LEVEL TROUGH AXIS MOVES INTO THE REGION.
SEASONABLY COOL WEEKEND IN STORE BEFORE TEMPS BEGIN TO INCREASE
AHEAD OF NEXT FRONTAL BOUNDARY WHICH MEDIUM RANGE MODELS WANT TO
BRING TOWARD THE END OF NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 99 57 83 54 / 30 40 0 0
HOBART OK 99 55 85 54 / 20 30 0 0
WICHITA FALLS TX 104 59 86 56 / 20 30 0 0
GAGE OK 88 53 83 49 / 20 10 0 0
PONCA CITY OK 93 53 82 54 / 40 20 0 0
DURANT OK 102 60 84 53 / 10 30 0 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...WIND ADVISORY FROM 4 PM THIS AFTERNOON TO 10 PM CDT THIS EVENING
FOR OKZ007-008-012-013-016>026-033>036.
WIND ADVISORY FROM NOON TODAY TO 6 PM CDT THIS EVENING FOR
OKZ004>006-009>011-014-015.
WIND ADVISORY FROM 6 PM TO 10 PM CDT THIS EVENING FOR OKZ027>031-
037>040-044-045.
TX...WIND ADVISORY FROM 6 PM TO 10 PM CDT THIS EVENING FOR TXZ083>090.
&&
$$
06/11
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1219 PM CDT FRI SEP 7 2012
.AVIATION...
STRONG COLD FRONT STILL PLOWING THROUGH THE REGION EARLY THIS
AFTERNOON IS EXPECTED TO MOVE THROUGH THE TAF SITES WITH THE NEXT
HOUR OR TWO. WINDS WILL SHARPLY TURN TO THE NORTH AND BECOME
SUSTAINED AROUND 20-25KT WITH GUSTS UP TO 35KT. THESE WINDS ARE
EXPECTED TO PERSIST THROUGH MUCH OF THE AFTERNOON BEFORE SLOWLY
DECREASING THIS EVENING. THERE IS AN OUTSIDE CHANCE OF LIGHT RAIN
SHOWERS IMMEDIATELY BEHIND THE FRONT WITHIN AN AREA OF MID LEVEL
CLOUDS. HOWEVER...A BETTER CHANCE FOR THUNDER WILL EXIST THIS
EVENING AT KLBB.
&&
.PREV DISCUSSION... /ISSUED 954 AM CDT FRI SEP 7 2012/
UPDATE...
LATEST OBSERVED TRENDS WITH THE FRONT SHOW IT IS MOVING A BIT QUICKER
THAN PREVIOUSLY ANTICIPATED WITH THE FRONT MOVING SOUTHWARD AT
A SPEED OF ABOUT 33KT. RAP ANALYSIS INDICATES IMPRESSIVE 8 MB PER
THREE HOUR PRESSURE RISES IN SOUTHEASTERN COLORADO. SUSTAINED
WINDS BEHIND THE FRONT WERE OBSERVED TO BE AROUND 25KT OR SO WITH
GUSTS UP TO 40 KT. HAVE UPDATED THE FORECAST FOR A FASTER FRONTAL
MOVEMENT AND TO ADD BLOWING DUST FOR THE REST OF THE MORNING IN
THE SOUTHWESTERN PANHANDLE AND NORTHERN SOUTH PLAINS.
PREV DISCUSSION... /ISSUED 255 AM CDT FRI SEP 7 2012/
SHORT TERM...
A BROAD UA TROUGH ACROSS THE NORTHERN ROCKIES/NORTHERN PLAINS...IS
PROGGED TO TRANSLATE SSE ACROSS THE CENTRAL PLAINS THIS
AFTERNOON/EVENING...WHICH WILL AID TO SHIFT THE CENTER OF THE UA
RIDGE WEST OF THE SOUTHERN PLAINS. THE TROUGH/S ASSOCIATED FROPA
WHICH WAS LOCATED ACROSS CENTRAL COLORADO AND NORTHERN KANSAS PER
07Z METARS...IS EXPECTED TO ENTER THE NWRN ZONES AOA 18Z AND THROUGH
THE REMAINDER OF THE CWA BY 00Z. WHAT NEEDS TO BE CONSIDERED WITH
THIS LATE SUMMER FRONTAL INTRUSION ARE /1/ PRECIPITATION CHANCES AND
/2/ THE STRENGTH OF THE FRONT.
BEST LARGE SCALE ASCENT IS FAVORED TO BE NORTH OF THE
REGION...HOWEVER FORECAST SOLUTIONS EXHIBITED PRECIP COMMENCING
BETWEEN 21-00Z ACROSS PORTIONS OF THE NRN AND CNTRL ZONES...THANKS
TO ADEQUATE FRONTOGENETICAL FORCING. THE PRECIP WILL SHIFT TO THE
CNTRL AND SRN ZONES THIS EVENING AND TONIGHT...WITH LINGERING PRECIP
ACROSS SRN ZONES EARLY TOMORROW MORNING /NEAREST TO BEST MOISTURE
AXIS/. IT IS INTERESTING TO NOTE MODEL RUNS SHOWING THE PRECIP IN A
RATHER NARROW CORRIDOR VERSUS WIDESPREAD CONVECTION. THIS IS LIKELY
DUE TO THE TOP-DOWN MOISTENING THAT WILL HAVE TO OCCUR GIVEN INITIAL
DRY LOW LEVELS...QUICKLY FOLLOWED BY A SFC RIDGING FILTERING IN A
MUCH DRIER AND COOLER AIRMASS FROM NORTH TO SOUTH. AS SUCH...CLOUD
BASES WILL BE RELATIVELY HIGH BUT INVERTED-V SOUNDING PROFILES
SUGGESTS THUNDERSTORM WIND GUSTS OF 40-50 MPH NOT OUT OF THE
QUESTION.
THE OTHER CONCERN IS HOW STRONG THIS NORTH TO NORTHEASTERLY FROPA
WILL BE. THE 1020 MB SFC RIDGE DRIVING THIS FRONT WILL PROMOTE A
TIGHTENED PRESSURE GRADIENT AND THUS PROGGED PRESSURE RISES OF 6-9
MB PER THREE HOURS /HIGHEST PRESSURE RISES EXPECTED TO BE ACROSS ERN
LOCALES/. MIXING TO 850 MB...FORECAST SOLUTIONS SHOW WIND SPEEDS OF
40-50 MPH AT THAT SAID LEVEL...WHICH CORRESPONDS TO 20-30 MPH AT THE
SFC...WHICH IS NEARING WIND ADVISORY SPEED CRITERIA /31-39 MPH/. AS
SUCH...SOME LOCALES ON THE CAPROCK COULD SEE AREAS OF BLOWING DUST.
IT IS QUITE POSSIBLE THAT A FEW LOCALES MAY CERTAINLY EQUATE THE
SPEED CRITERIA OF THE WIND ADVISORY BUT CONFIDENCE IS NOT HIGH FOR
THIS TO OCCUR FOR AN HOUR OR LONGER /SECOND HALF OF THE WIND
ADVISORY CRITERIA/...GIVEN THE RELATIVELY QUICK DECLINATION IN
PRESSURE RISES. THE DAY SHIFT WILL HAVE TO KEEP AN EYE ON THE
STRENGTH OF THE FRONT AS IT NEARS DRAWS...ESPECIALLY IF IT
APPROACHES THE AIRPORT WEATHER WARNING CRITERIA /SFC WINDS OF 30 KTS
OR GREATER/. WILL THEREFORE MAINTAIN A MENTION IN THE HAZARDOUS
WEATHER OUTLOOK ATTM. FURTHERMORE...THE STRENGTH OF THE COLD FRONT
COMBINED WITH THE ASSOCIATED CLOUD COVER WILL CREATE A TEMP-GRADIENT
FROM NW /LOWER 80S/ TO SE /LOWER TRIPLE DIGITS/.
LONG TERM...
A COOL AND DRY AIR MASS WILL SPREAD ACROSS THE FCST AREA SATURDAY
WITH POTENTIAL FOR A FEW LINGERING SHOWERS ACROSS THE SWRN ZONES
EARLY IN THE DAY. RETURN FLOW AND A WARMING TREND THEN QUICKLY SET
UP SUNDAY AS UPPER LEVEL RIDGING BEGINS TO BUILD EWD ONCE AGAIN.
THEN THROUGH THE COURSE OF NEXT WEEK WILL SEE A VERY SLOWLY
PROGRESSIVE PATTERN WITH THE UPPER RIDGE CONTINUE TO MOVE EWD...
FLATTENING UPPER LEVEL FLOW ACROSS THE SRN PLAINS...AND THE
APPROACH OF A LOW AMPLITUDE SHORT WAVE TROUGH FROM THE WEST TOWARD
THE MIDDLE OF THE WEEK. CONTINUOUS SOUTHERLY FLOW EARLY IN THE
WEEK WILL EVENTUALLY DRAW SOME LOW LEVEL MOISTURE NWD...BUT
WHETHER IT AND FORCING ASSOCIATED WITH THE AFOREMENTIONED TROUGH
WILL BE ENOUGH TO GENERATE SOME PRECIP BY ABOUT WEDNESDAY OR
THURSDAY REMAINS UNCERTAIN. GFS DEPICTS BETTER RAIN CHANCES VERY
LATE IN THE FCST PERIOD TOWARD THE END OF THE WEEK WITH THE
PASSAGE OF THE NEXT COLD FRONT. ECMWF NOT YET IN AGREEMENT...SO
TIME WILL TELL IF THIS WILL PAN OUT. FOR NOW WILL MAINTAIN A DRY
FCST FOR THE UPCOMING WEEK. HIGH TEMPS TO RETURN TO THE UPPER 80S
AND 90S FOR MUCH OF THE WEEK...BUT ATTM IT APPEARS REACHING THE
CENTURY MARK AGAIN IN ANY PART OF THE FCST AREA IS UNLIKELY.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 54 76 48 83 53 / 20 0 0 0 0
TULIA 55 76 49 83 54 / 20 0 0 0 0
PLAINVIEW 56 76 49 85 54 / 30 0 0 0 0
LEVELLAND 56 76 48 82 55 / 30 10 0 0 0
LUBBOCK 57 77 51 85 55 / 30 10 0 0 0
DENVER CITY 58 75 50 82 56 / 40 20 0 0 0
BROWNFIELD 57 76 52 83 57 / 40 20 0 0 0
CHILDRESS 59 80 55 88 57 / 30 0 0 0 0
SPUR 60 79 52 85 56 / 30 10 0 0 0
ASPERMONT 62 80 57 87 57 / 30 10 0 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
954 AM CDT FRI SEP 7 2012
.UPDATE...
LATEST OBSERVED TRENDS WITH THE FRONT SHOW IT IS MOVING A BIT QUICKER
THAN PREVIOUSLY ANTICIPATED WITH THE FRONT MOVING SOUTHWARD AT
A SPEED OF ABOUT 33KT. RAP ANALYSIS INDICATES IMPRESSIVE 8 MB PER
THREE HOUR PRESSURE RISES IN SOUTHEASTERN COLORADO. SUSTAINED
WINDS BEHIND THE FRONT WERE OBSERVED TO BE AROUND 25KT OR SO WITH
GUSTS UP TO 40 KT. HAVE UPDATED THE FORECAST FOR A FASTER FRONTAL
MOVEMENT AND TO ADD BLOWING DUST FOR THE REST OF THE MORNING IN
THE SOUTHWESTERN PANHANDLE AND NORTHERN SOUTH PLAINS.
&&
PREV DISCUSSION... /ISSUED 255 AM CDT FRI SEP 7 2012/
SHORT TERM...
A BROAD UA TROUGH ACROSS THE NORTHERN ROCKIES/NORTHERN PLAINS...IS
PROGGED TO TRANSLATE SSE ACROSS THE CENTRAL PLAINS THIS
AFTERNOON/EVENING...WHICH WILL AID TO SHIFT THE CENTER OF THE UA
RIDGE WEST OF THE SOUTHERN PLAINS. THE TROUGH/S ASSOCIATED FROPA
WHICH WAS LOCATED ACROSS CENTRAL COLORADO AND NORTHERN KANSAS PER
07Z METARS...IS EXPECTED TO ENTER THE NWRN ZONES AOA 18Z AND THROUGH
THE REMAINDER OF THE CWA BY 00Z. WHAT NEEDS TO BE CONSIDERED WITH
THIS LATE SUMMER FRONTAL INTRUSION ARE /1/ PRECIPITATION CHANCES AND
/2/ THE STRENGTH OF THE FRONT.
BEST LARGE SCALE ASCENT IS FAVORED TO BE NORTH OF THE
REGION...HOWEVER FORECAST SOLUTIONS EXHIBITED PRECIP COMMENCING
BETWEEN 21-00Z ACROSS PORTIONS OF THE NRN AND CNTRL ZONES...THANKS
TO ADEQUATE FRONTOGENETICAL FORCING. THE PRECIP WILL SHIFT TO THE
CNTRL AND SRN ZONES THIS EVENING AND TONIGHT...WITH LINGERING PRECIP
ACROSS SRN ZONES EARLY TOMORROW MORNING /NEAREST TO BEST MOISTURE
AXIS/. IT IS INTERESTING TO NOTE MODEL RUNS SHOWING THE PRECIP IN A
RATHER NARROW CORRIDOR VERSUS WIDESPREAD CONVECTION. THIS IS LIKELY
DUE TO THE TOP-DOWN MOISTENING THAT WILL HAVE TO OCCUR GIVEN INITIAL
DRY LOW LEVELS...QUICKLY FOLLOWED BY A SFC RIDGING FILTERING IN A
MUCH DRIER AND COOLER AIRMASS FROM NORTH TO SOUTH. AS SUCH...CLOUD
BASES WILL BE RELATIVELY HIGH BUT INVERTED-V SOUNDING PROFILES
SUGGESTS THUNDERSTORM WIND GUSTS OF 40-50 MPH NOT OUT OF THE
QUESTION.
THE OTHER CONCERN IS HOW STRONG THIS NORTH TO NORTHEASTERLY FROPA
WILL BE. THE 1020 MB SFC RIDGE DRIVING THIS FRONT WILL PROMOTE A
TIGHTENED PRESSURE GRADIENT AND THUS PROGGED PRESSURE RISES OF 6-9
MB PER THREE HOURS /HIGHEST PRESSURE RISES EXPECTED TO BE ACROSS ERN
LOCALES/. MIXING TO 850 MB...FORECAST SOLUTIONS SHOW WIND SPEEDS OF
40-50 MPH AT THAT SAID LEVEL...WHICH CORRESPONDS TO 20-30 MPH AT THE
SFC...WHICH IS NEARING WIND ADVISORY SPEED CRITERIA /31-39 MPH/. AS
SUCH...SOME LOCALES ON THE CAPROCK COULD SEE AREAS OF BLOWING DUST.
IT IS QUITE POSSIBLE THAT A FEW LOCALES MAY CERTAINLY EQUATE THE
SPEED CRITERIA OF THE WIND ADVISORY BUT CONFIDENCE IS NOT HIGH FOR
THIS TO OCCUR FOR AN HOUR OR LONGER /SECOND HALF OF THE WIND
ADVISORY CRITERIA/...GIVEN THE RELATIVELY QUICK DECLINATION IN
PRESSURE RISES. THE DAY SHIFT WILL HAVE TO KEEP AN EYE ON THE
STRENGTH OF THE FRONT AS IT NEARS DRAWS...ESPECIALLY IF IT
APPROACHES THE AIRPORT WEATHER WARNING CRITERIA /SFC WINDS OF 30 KTS
OR GREATER/. WILL THEREFORE MAINTAIN A MENTION IN THE HAZARDOUS
WEATHER OUTLOOK ATTM. FURTHERMORE...THE STRENGTH OF THE COLD FRONT
COMBINED WITH THE ASSOCIATED CLOUD COVER WILL CREATE A TEMP-GRADIENT
FROM NW /LOWER 80S/ TO SE /LOWER TRIPLE DIGITS/.
LONG TERM...
A COOL AND DRY AIR MASS WILL SPREAD ACROSS THE FCST AREA SATURDAY
WITH POTENTIAL FOR A FEW LINGERING SHOWERS ACROSS THE SWRN ZONES
EARLY IN THE DAY. RETURN FLOW AND A WARMING TREND THEN QUICKLY SET
UP SUNDAY AS UPPER LEVEL RIDGING BEGINS TO BUILD EWD ONCE AGAIN.
THEN THROUGH THE COURSE OF NEXT WEEK WILL SEE A VERY SLOWLY
PROGRESSIVE PATTERN WITH THE UPPER RIDGE CONTINUE TO MOVE EWD...
FLATTENING UPPER LEVEL FLOW ACROSS THE SRN PLAINS...AND THE
APPROACH OF A LOW AMPLITUDE SHORT WAVE TROUGH FROM THE WEST TOWARD
THE MIDDLE OF THE WEEK. CONTINUOUS SOUTHERLY FLOW EARLY IN THE
WEEK WILL EVENTUALLY DRAW SOME LOW LEVEL MOISTURE NWD...BUT
WHETHER IT AND FORCING ASSOCIATED WITH THE AFOREMENTIONED TROUGH
WILL BE ENOUGH TO GENERATE SOME PRECIP BY ABOUT WEDNESDAY OR
THURSDAY REMAINS UNCERTAIN. GFS DEPICTS BETTER RAIN CHANCES VERY
LATE IN THE FCST PERIOD TOWARD THE END OF THE WEEK WITH THE
PASSAGE OF THE NEXT COLD FRONT. ECMWF NOT YET IN AGREEMENT...SO
TIME WILL TELL IF THIS WILL PAN OUT. FOR NOW WILL MAINTAIN A DRY
FCST FOR THE UPCOMING WEEK. HIGH TEMPS TO RETURN TO THE UPPER 80S
AND 90S FOR MUCH OF THE WEEK...BUT ATTM IT APPEARS REACHING THE
CENTURY MARK AGAIN IN ANY PART OF THE FCST AREA IS UNLIKELY.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 83 54 76 48 83 / 20 20 0 0 0
TULIA 84 55 76 49 83 / 20 20 0 0 0
PLAINVIEW 86 56 76 49 85 / 20 30 0 0 0
LEVELLAND 88 56 76 48 82 / 20 30 10 0 0
LUBBOCK 88 57 77 51 85 / 20 30 10 0 0
DENVER CITY 95 58 75 50 82 / 20 40 20 0 0
BROWNFIELD 95 57 76 52 83 / 20 40 20 0 0
CHILDRESS 93 59 80 55 88 / 20 30 0 0 0
SPUR 98 60 79 52 85 / 20 30 10 0 0
ASPERMONT 100 62 80 57 87 / 20 30 10 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1028 PM CDT SAT SEP 8 2012
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SHORT TERM...TONIGHT THROUGH SUNDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A VIGOROUS AND
COMPACT SHORTWAVE TROUGH MOVING SOUTHEAST INTO NORTHWEST WISCONSIN
EARLY THIS AFTERNOON. LEADING BAND OF SHOWERS IS DIVING ACROSS
NORTH-CENTRAL WISCONSIN...WHILE ADDITIONAL SHOWER ACTIVITY EXISTS
ACROSS THE ARROWHEAD OF MINNESOTA IN THE WRAP-AROUND REGION OF THE
SYSTEM. A REINFORCEMENT OF COOLER AIR IS FOLLOWING IN THE WAKE OF
THE SHORTWAVE WHERE 850MB TEMPS ARE FALLING BELOW 4C OVER NORTHERN
MINNESOTA AND WESTERN ONTARIO. PRECIP TRENDS ARE THE MAIN FORECAST
CONCERN OVER THE NEXT 24 HOURS.
TONIGHT...COMPACT YET POTENT SHORTWAVE TROUGH WILL CONTINUE TO DIVE
SE AND EXIT THE STATE BY MID-EVENING. LOW LEVEL TROUGH BENEATH
PLENTY OF MID-LEVEL MOISTURE WILL KEEP LIKELY TO DEFINITE SHOWERS
AROUND OVER CENTRAL AND NORTHEAST WISCONSIN FOR THE FIRST HALF OF
THE EVENING. SOME SHOWERS BEHIND THE SYSTEM AS WELL OVER THE
ARROWHEAD SO DECIDED TO KEEP A LOW END CHANCE OF SHOWERS OVER N-C
WISCONSIN. THEREAFTER...SHOULD SEE SHOWERS EXIT EAST-CENTRAL
WISCONSIN BY LATE EVENING WHILE DELTA T/S OVER WESTERN LAKE SUPERIOR
INCREASE TO 14-15C IN NORTHERLY FLOW. WITH RICH ENOUGH MOISTURE IN
THE 850-700MB LAYER...LAKE EFFECT SHOWERS LOOK TO BE A GOOD BET TO
DEVELOP LATER THIS EVENING AND OVERNIGHT. AS A RESULT...CLOUDS WILL
BE SLOWER TO DEPART OVER CENTRAL AND NORTH-CENTRAL WISCONSIN THAN
FARTHER EAST WHERE MODELS SHOW DRY AIR FROM EASTERN ONTARIO SURGING
SOUTH OVER NORTHEAST WISCONSIN. TEMPS FALLING INTO THE 40S
NORTHWEST OF THE FOX VALLEY...AND INTO THE LOWER 50S ELSEWHERE.
SUNDAY...CANADIAN HIGH PRESSURE WILL BE BUILDING INTO THE STATE
THROUGH THE DAY. NORTHERLY FLOW AHEAD OF THE SURFACE HIGH WILL
CONTINUE TO SEND LAKE EFFECT CLOUDS AND SPOTTY SHOWERS INTO
NORTH-CENTRAL WISCONSIN THROUGH THE MORNING. ELSEWHERE...DIURNAL CU
WILL BE BUILDING BY MIDDAY WHICH WILL LEAD TO A PARTLY CLOUDY DAY.
HIGHS RANGING FROM THE MID 60S NORTH TO LOW 70S SOUTH.
.LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY...TEMPERATURES
THROUGHOUT THE PERIOD...AND PCPN CHANCES FOR THE MID TO LATE PART
OF THE WORK WEEK...ARE THE MAIN FCST CONCERNS.
COOL CANADIAN HIGH PRESSURE WILL RESIDE OVER THE REGION AT THE
BEGINNING OF THE PERIOD. COULD SEE SOME PATCHY FROST OVER PARTS
OF NORTHERN WI...WITH MIN TEMPS EXPECTED TO DROP INTO THE MID TO
UPPER 30S IN THE TYPICAL COLD SPOTS.
RETURN FLOW ON THE BACK SIDE OF THE HIGH WILL RESULT IN A WARM-UP
ON MONDAY AND TUESDAY...WITH TEMPERATURES RISING TO WELL ABOVE
NORMAL LEVELS AGAIN BY TUESDAY. BREEZY CONDITIONS WILL ALSO DEVELOP
ON TUESDAY...AS THE PRESSURE GRADIENT STRENGTHENS BETWEEN THE
DEPARTING HIGH AND A COLD FRONT MOVG INTO MINNESOTA.
THE COLD FRONT WILL EDGE TOWARD NC WI LATE TUESDAY NIGHT...THEN
MOVE SLOWLY SE THROUGH THE FORECAST AREA ON WEDS/WEDS NGT/THU.
WITH AN UPPER TROF AND THE RRQ OF AN UPPER LEVEL JET LAGGING TO
THE WEST OF THE FRONT...PCPN IS EXPECTED TO BE POST-FRONTAL. WILL
HAVE CHC POPS OVER NC WI ON WEDS...ACROSS MOST OF THE CWA ON WEDS
NGT...AND CONTINUING OVER AT LEAST OUR SE COUNTIES ON THU/THU NGT.
THE 12Z ECMWF HAS CAST SOME DOUBT ON THIS SCENARIO...AS IT
REDEVELOPS PCPN ACROSS MOST OF WISCONSIN FROM THURSDAY NIGHT
THROUGH FRIDAY NIGHT...AS IT LIFTS A SFC WAVE NEWD ALONG THE
STALLED FRONTAL BOUNDARY. THIS CANNOT BE RULED OUT...GIVEN THE
FAIRLY POTENT UPPER TROF/JET STREAK PREDICTED BY THE MODELS. WILL
NEED TO WATCH THE TRENDS ON THIS OVER THE NEXT FEW DAYS.
ANOTHER COOLER CANADIAN AIR MASS WILL BUILD INTO THE REGION IN
THE WAKE OF THE COLD FRONT...ALLOWING TEMPERATURES TO DROP TO
AROUND SEASONAL NORMALS FOR MID-SEPTEMBER.
&&
.AVIATION...DRIER AIR WAS FILTERING INTO THE STATE IN THE WAKE OF
AN UPPER LOW AND COLD FRONT PASSAGE EARLIER THIS EVENING.
SCATTERED MVFR CIGS OVER NORTHERN WISCONSIN WILL GRADUALLY
DISSIPATE WHILE WORKING SOUTH. EVENTUALLY VFR CIGS WILL PREVAIL BY
MORNING AND WILL CONTINUE INTO SUNDAY.
TDH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
248 PM CDT FRI SEP 7 2012
.SHORT TERM...TONIGHT THROUGH MONDAY
248 PM CDT FRI SEP 7 2012
MAIN FORECAST CONCERNS ARE ON TEMPERATURES THROUGH THE WEEKEND AND
RAIN CHANCES SATURDAY AFTERNOON INTO SATURDAY EVENING.
LATEST WATER VAPOR IMAGERY SHOWED AN ELONGATED UPPER TROUGH EXTENDING
FROM JAMES BAY SOUTHWEST THROUGH MINNESOTA AND ACROSS SOUTH DAKOTA.
THE TROUGH WAS MOVING SOUTH ACROSS THE UPPER MISSISSIPPI RIVER
VALLEY.
MUCH COOLER AIR WILL MOVE INTO THE REGION TONIGHT IN THE WAKE OF A
SECONDARY COLD FRONT PUSHING THROUGH THE REGION. SKIES WILL RANGE
FROM PARTLY CLOUDY TO MOSTLY CLEAR BY LATE THIS EVENING AS
SUBSIDENCE SLIDES OVER THE AREA IN THE WAKE OF THE DEPARTING
TROUGH. PLAN ON LOW TEMPERATURES IN THE 40S WITH LOW LYING AREAS
SUCH AS DIAMOND LAKE...BLACK RIVER FALLS....AND SPARTA FALLING
INTO THE UPPER 30S. THE FORECAST AREA WILL BE IN A TIGHT PRESSURE
GRADIENT THROUGH THE OVERNIGHT HOURS WITH SURFACE HIGH PRESSURE
CENTERED OF THE DAKOTAS AND THE SURFACE TROUGH MOVING ACROSS THE
EASTERN GREAT LAKES. NORTHWEST WINDS ARE EXPECTED TO SUBSIDE LATE
THIS EVENING. WINDS ALOFT SHOULD HELP TO PROMOTE MIXING AND LIMIT
FOG DEVELOPMENT. HOWEVER...SHOULD SEE SOME FOG IN THE LOW LYING
AREAS THAT DECOUPLE GIVEN THE RECENT RAINFALL AND CLOUDS OVER THE
REGION THROUGH MUCH OF THE DAYTIME HOURS. WOULD EXPECT THE FOG TO
BE SHALLOW AND PATCHY WITH VISIBILITIES POSSIBLY REDUCED TO AROUND
1/2 MILE OR LESS IF IT DEVELOPS.
ANOTHER TROUGH IS EXPECTED TO DIVE INTO THE REGION ON SATURDAY FROM
MANITOBA/ONTARIO. THE TROUGH WILL MOVE INTO THE FORECAST AREA
SATURDAY AFTERNOON. SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED
TO DEVELOP ACROSS NORTH CENTRAL INTO CENTRAL WISCONSIN DURING THE
AFTERNOON HOURS. SCATTERED TO ISOLATED SHOWERS AND EXPECTED ACROSS
WEST CENTRAL INTO PORTIONS OF SOUTHWEST WISCONSIN. SOUNDINGS ARE
SHOWING VERY DRY AIR NEAR THE SURFACE...ESPECIALLY ALONG AND WEST OF
THE MISSISSIPPI RIVER. DECIDED KEEP LOCATIONS WEST OF THE
MISSISSIPPI RIVER DRY WHERE CLOUDS WILL BE ON THE INCREASE DURING
THE AFTERNOON HOURS BUT NOT EXPECTING ANY SHOWERS THAT FAR WEST.
PLAN ON HIGHS ON SATURDAY BEING REACHED IN THE LATE MORNING HOURS
BEFORE CLOUDS SPREAD INTO THE REGION. LOOK FOR HIGHS TO RANGE FROM
THE MID 60S ACROSS NORTHERN WISCONSIN TO THE MID 70S OVER NORTHEAST
IOWA.
THE TROUGH WILL SLIDE EAST OF THE REGION LATE SATURDAY NIGHT INTO
SUNDAY AS SURFACE HIGH PRESSURE BUILDS IN TO THE REGION. LOOK FOR
DECREASING CLOUDS LATE SUNDAY EVENING WITH SKIES BECOMING MOSTLY
CLEAR DURING THE OVERNIGHT HOURS. THE HIGH WILL DOMINATE THE WEATHER
ON SUNDAY WITH MOSTLY SUNNY SKIES ACROSS THE REGION. LOOK FOR HIGHS
TO RANGE FROM THE UPPER 60S ACROSS NORTHERN WISCONSIN TO THE LOWER
70S OVER NORTHEAST IOWA. THE SYNOPTIC SET UP LOOKS VERY FAVORABLE
FOR VALLEY FOG LATE SUNDAY NIGHT INTO EARLY SUNDAY MORNING. HIGH
PRESSURE OVERHEAD....CLEAR SKIES...CALM TO LIGHT WINDS FROM THE
SURFACE THROUGH 6 KFT. DECIDED TO ADD AREAS OF FOG TO THE RIVER
VALLEYS LATE SUNDAY NIGHT THROUGH EARLY MONDAY MORNING. THE SURFACE
HIGH WILL SLIDE EAST LATE ON MONDAY AS AN UPPER LEVEL RIDGE MOVE INTO
THE REGION. SOUTHERLY FLOW WILL INCREASE ACROSS THE AREA AS A
SURFACE TROUGH DEVELOPS OVER THE HIGH PLAINS. THE SOUTHERLY FLOW
WILL USHER IN WARMER TEMPERATES WITH HIGHS IN THE 70S TO AROUND
80.
.LONG TERM...TUESDAY THROUGH FRIDAY
248 PM CDT FRI SEP 7 2012
07.12 MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT THROUGH THE
EXTENDED PERIOD. HAVE WARMED HIGHS A FEW DEGREES ON TUESDAY OVER
THE PREVIOUS FORECAST GIVEN THE STRONG SOUTHWEST FLOW AT NEAR THE
SURFACE AND THE UPPER RIDGE OVERHEAD. IN ADDITION...ECMWF 850MB
TEMPERATURE STANDARDIZED ANOMALIES ARE AROUND PLUS 1.5. FLOW ALOFT
WILL TURN SOUTHWEST TUESDAY NIGHT INTO WEDNESDAY AS A TROUGH MOVES
INTO THE NORTHERN PLAINS AND EDGES EAST INTO THE UPPER MISSISSIPPI
RIVER VALLEY. THE TROUGH WILL INTERACT WITH A FRONTAL BOUNDARY
GRADUALLY MOVING FROM NORTHWEST TO SOUTHEAST ACROSS THE FORECAST
AREA. PLAN ON CHANCES FOR SHOWERS AND THUNDERSTORMS FROM TUESDAY
NIGHT THROUGH EARLY THURSDAY AS THE FRONT SLOWLY DRIFTS ACROSS THE
AREA. COOLER AIR WILL RETURN BEHIND THE FRONT WITH HIGHS ON
WEDNESDAY FALLING BACK INTO THE LOWER 70S BEHIND THE FRONT...ACROSS
SOUTHEAST MINNESOTA INTO NORTH CENTRAL WISCONSIN. HIGHS WILL BE IN THE
70S TO LOWER 80S ACROSS PORTIONS OF NORTHEAST IOWA INTO FAR
SOUTHWEST WISCONSIN BEFORE THE FRONT MOVES THROUGH. SHOWER AND
THUNDERSTORMS CHANCES WILL FINALLY SHIFT SOUTH OF THE AREA ON FRIDAY
AS HIGH PRESSURE BUILDS IN.
&&
.AVIATION...THROUGH 18Z SATURDAY
1221 PM CDT FRI SEP 7 2012
UPPER TROUGH WILL ROTATE ACROSS THE AREA THIS AFTERNOON.
FRONTOGENETICALLY FORCED SHOWERS NOW MOVING THROUGH SOUTHEAST
MINNESOTA INTO WESTERN WISCONSIN. MAIN BAND SHOULD BE SOUTH OF THE
THE TAF SITES BY 18Z. HOWEVER...COULD SEE SOME REDEVELOPMENT BEHIND
THIS BAND BETWEEN 18Z-20Z AND NOTED ON THE 07/12 ARXLAPS AND
07.13Z HRRR...WILL KEEP VCSH AT BOTH SITES THROUGH 20Z. CEILINGS
EXPECTED TO REMAIN IN THE VFR CATEGORY WITH BASES 4K-6K FEET...ANY
MVFR CEILINGS WITH SHOWERS WILL BE SHORT LIVED. SUBSIDENCE IN THE
WAKE OF THE TROUGH WILL OVERSPREAD THE AREA THIS EVENING WITH
CLEARING SKIES. BOTH THE 07.12Z NAM AND 07.15Z RAP BUFKIT
SOUNDINGS DO SHOW WINDS TO REMAIN RATHER STRONG JUST ABOVE THE
SURFACE THROUGH THE OVERNIGHT HOURS. THUS DESPITE CLEARING SKIES
AND THE RECENT RAIN NOT EXPECTING ANY FOG FORMATION AT EITHER TAF
SITE.
DECENT MIXING LATER SATURDAY MORNING AND PRESSURE GRADIENT TO
REMAIN STRONG DID ADD SOME GUST TO NEAR 20 KNOTS AT BOTH KLSE AND
KRST AFTER 16Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
248 PM CDT FRI SEP 7 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1221 PM CDT FRI SEP 7 2012
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
327 AM CDT FRI SEP 7 2012
MAIN FORECAST CONCERNS THIS PACKAGE...SHRA/TSRA CHANCES TODAY...
SHRA CHANCES WITH SECONDARY FRONTAL/SHORTWAVE PASSAGE SAT...
TEMPERATURES THRU THE PERIOD.
06Z DATA ANALYSIS HAD LOW PRESSURE OVER JAMES BAY WITH A TROUGH
SOUTHWEST TO A LOW NEAR KOMA. 850-700MB MOISTURE TRANSPORT/THETA-E
CONVERGENCE AND WARM ADVECTION AHEAD OF THE KOMA LOW PRODUCING
SHRA/TSRA OVER MUCH OF CENTRAL/NORTHERN IA. FURTHER NORTH...SOME
850-700MB WARM ADVECTION AND FN-CONVERGENCE ALONG WITH INCREASING
PV ADVECTION ALOFT PRODUCING SHRA OVER MUCH OF NORTHERN WI INTO
CENTRAL MN. WITH ALL THE CLOUD COVER AND BROAD LOW LEVEL WARM
ADVECTION...EARLY MORNING TEMPS GENERALLY ON THE MILD SIDE FOR
EARLY SEPT.
NO BIG ERRORS NOTED WITH 07.00Z MODEL INITIALIZATIONS. SOLUTIONS
RATHER SIMILAR FOR TODAY THRU SUN NIGHT BUT FOR SOME DIFFERENCES
WITH SHRA CHANCES ON SAT...RELATED TO TRACK OF A SECONDARY
SHORTWAVE DROPPING OUT OF CANADA. DPROG/DT OF 500MB HGTS AT 07.00Z
SHOWED THE MODEL RUNS OF 05.00Z AND 6.00Z VERIFIED VERY WELL ACROSS
NOAM/EASTERN PAC. TREND FAVORS A TIGHTER COMPROMISE OF THE EARLIER
RUNS ON MOST FEATURES...BUT STRONGER OF EARLIER RUNS ON THE
SHORTWAVE DROPPING SOUTH NEAR LK WINNIPEG EARLY THIS MORNING. BETTER
CONSENSUS THRU TODAY/TONIGHT AS THE LK WINNIPEG SHORTWAVE/TROUGH
DROPS SOUTH ACROSS THE REGION...TOWARD A COMPROMISE OF THE EARLIER
RUNS. TREND IS A BIT STRONGER WITH THE NEXT SHORTWAVE DROPPING
SOUTHEAST ACROSS MAN/WESTERN ONT. CONSENSUS CONTINUES TO IMPROVE AS
THIS SHORTWAVE PASSES SAT/SAT NIGHT AND STRONG TROUGHING DEVELOPS
OVER THE EASTERN CONUS. GOOD CONSENSUS FOR THE PATTERN TO BE
PROGRESSIVE AND RIDGING ALOFT TO BUILD INTO THE NORTH-CENTRAL CONUS
SUN/SUN NIGHT. CHECK OF OBS VS. MODEL DATA AT 06Z SHOWED ALL
REASONABLE WITH THE SFC MASS FIELDS ACROSS THE NORTH-CENTRAL CONUS.
PER WV IMAGERY NAM/GFS/ECMWF LOOKED BETTER WITH THE LK WINNIPEG
SHORTWAVE...GEM LOOKED TO FAR EAST. GEM DID LOOK GOOD WITH THE
SHORTWAVE OVER NORTHERN BC...MODELS ALL GENERALLY GOOD WITH THE 00-
06Z SHRA/RAIN OVER NORTH-CENTRAL MN/NORTHERN WI WHILE MOST WERE TOO
FAR SOUTH WITH THE SHRA/TSRA OVER IA. NO CLEAR FAVORITE AND WITH A
TREND TOWARD A TIGHTER COMPROMISE...PREFERRED A MODEL/ENSEMBLE BLEND
THIS CYCLE. SHORT TERM FCST CONFIDENCE GENERALLY GOOD THIS CYCLE.
IN THE SHORT TERM...MAIN FORCING/LIFT TODAY WILL COME FROM PV
ADVECTION AS THE LK WINNIPEG SHORTWAVE DROPS SOUTH-SOUTHEAST ACROSS
THE REGION AND 850-500MB FN CONVERGENCE WITH THE MID LEVEL TROUGH.
THIS FORCING/LIFT WILL EVENTUALLY INTERACT WITH THE DEEPER MOISTURE
SPREADING NORTHEAST ACROSS IA INTO SOUTHERN WI...WITH SHRA EXPECTED
TO BECOME MORE WIDESPREAD AS THE LIFT MOVES SOUTH/EAST ACROSS THE
AREA. INSTABILITY REMAINS LIMITED AND MAINLY CONFINED TO THE SOUTH
END OF THE FCST AREA THIS MORNING. LIMITED TSRA MENTION AS ISOLATED
OVER THE SOUTHEAST 1/4 OF THE FCST AREA THIS MORNING. CONTINUED
HIGHEST RAIN CHANCES OVER THE SOUTH/EAST 2/3 OF THE FCST AREA THIS
MORNING AND RAISED THESE A BIT OVER THE SOUTHEAST END WHERE THE
DEEPER MOISTURE WILL RESIDE. ONCE THE SHORTWAVE/TROUGH AXIS
PASSES...LIFT SHUTS OFF VERY QUICKLY WITH SUBSIDENCE/DRYING
SPREADING SOUTHEAST ACROSS THE FCST AREA DURING THE AFTERNOON.
LIMITED SHRA CHANCES AFTER 18Z TO 20-40 PERCENT AND MAINLY OVER THE
SOUTHEAST HALF OF THE FCST AREA.
SUBSIDENCE/DRYING/LOW LEVEL COLD ADVECTION CONTINUE TO SPREAD
SOUTHEAST ACROSS THE UPPER MIDWEST TONIGHT. A SEASONABLY COOL NIGHT
TONIGHT WITH MOSTLY CLEAR SKIES...LIGHT WINDS AND 850-700MB COOL
POOL OVER THE AREA.
925-700MB WARM ADVECTION QUICKLY RETURNS SAT...AHEAD OF THE NEXT
SHORTWAVE/TROUGH AND SFC COLD FRONT. MOISTURE LIMITED AHEAD OF
THIS TROUGH/FRONT WITH PW VALUES OF 0.5 TO 0.75 INCH. ON THE PLUS
SIDE IS RATHER STRONG 500-300 PV ADVECTION FOR LIFT AHEAD OF THE
SHORTWAVE. QUESTION IS WHERE WILL THE SHORTWAVE TRACK. GEM/ECMWF A
COUPLE OF THE FURTHER WEST SOLUTIONS WITH THE TRACK OF THE
SHORTWAVE...AND STRONGER LIFT/SATURATION OVER THE NORTHEAST END OF
THE FCST AREA SAT AFTERNOON/EVENING. WITH THE TREND TOWARD STRONGER
AS THIS FEATURE DROPS ACROSS THE REGION...CONTINUED A SLIGHT CHANCE
OF SHRA MAINLY ALONG/NORTHEAST OF I-94 SAT AFTERNOON/EVENING.
DRY..QUIET WEATHER RETURNS FOR LATER SAT NIGHT INTO MON NIGHT AS
HGTS ALOFT GRADUALLY RISE AND CANADIAN HIGH PRESSURE DRIFTS
SOUTHEAST ACROSS THE UPPER MIDWEST. CENTER OF THE HIGH MOVES OVER
THE AREA SUN NIGHT. DEPENDING ON HOW DRY THE AIRMASS IS OVER THE
AREA SUN/SUN NIGHT...THERE MAY BE VALLEY FOG POTENTIAL LATE SUN
NIGHT INTO MON MORNING. SYNOPTIC SET-UP WILL BE FAVORABLE WITH
STRONG DECOUPLING DURING THE EVENING...HOWEVER MODELS TRENDING
TOWARD A RATHER DRY AIRMASS OVER THE AREA SUN NIGHT AND LEFT ANY
FOG MENTION OUT OF THE GRIDS FOR NOW.
TRENDED TOWARD A BLEND OF THE NUMERICAL TEMP GUIDANCE FOR HIGHS/LOWS
TODAY THRU SUN NIGHT...WITH TEMPS A CATEGORY OR TWO BELOW NORMAL.
.LONG TERM...MONDAY THROUGH THURSDAY
327 AM CDT FRI SEP 7 2012
MEDIUM RANGE MODEL RUNS OF 07.00Z IN GOOD AGREEMENT MON/TUE AS THE
MID LEVEL RIDGE AXIS MOVES EAST ACROSS THE UPPER MIDWEST. LOWER
LEVEL WARM ADVECTION INCREASES MON/TUE AS THE SFC HIGH MOVES INTO
THE OH VALLEY...TROUGHING DEVELOPS IN THE CENTRAL/NORTHERN PLAINS
AND THE PRESSURE GRADIENT TIGHTENS OVER THE REGION. TEMPS MON/TUE
RETURN TO NEAR/ABOVE NORMAL AS THE 850-700MB THERMAL RIDGE AHEAD
OF THE TROUGHING BUILDS INTO THE AREA. MODEL CONSENSUS REMAINS
REASONABLE WED/THU AS THE NEXT TROUGH MOVES EAST ALONG THE US/CAN
BORDER. THIS TROUGH PUSHES A COLD FRONT INTO/ACROSS THE AREA
CENTERED ON WED. QUESTION WILL BE EXTENT OF MOISTURE DRAWN NORTHWARD
AHEAD OF THIS FEATURE WITH AUTUMN PROGRESSING...CROPS/VEGETATION
SOME 2-3 WEEKS AHEAD OF NORMAL...MATURING AND SHUTTING DOWN WITH
EVAPO-TRANSPIRATION WANING. SHRA/TSRA CHANCES IN THE 20-30 PERCENT
RANGE FOR WED INTO THU REASONABLE FOR NOW. WITH MORE CLOUDS AND
PASSAGE OF THE COLD FRONT...TEMPS CLOSER TO NORMAL FOR WED/THU LOOK
WELL TRENDED AT THIS TIME.
&&
.AVIATION...THROUGH 18Z SATURDAY
1221 PM CDT FRI SEP 7 2012
UPPER TROUGH WILL ROTATE ACROSS THE AREA THIS AFTERNOON.
FRONTOGENETICALLY FORCED SHOWERS NOW MOVING THROUGH SOUTHEAST
MINNESOTA INTO WESTERN WISCONSIN. MAIN BAND SHOULD BE SOUTH OF THE
THE TAF SITES BY 18Z. HOWEVER...COULD SEE SOME REDEVELOPMENT BEHIND
THIS BAND BETWEEN 18Z-20Z AND NOTED ON THE 07/12 ARXLAPS AND
07.13Z HRRR...WILL KEEP VCSH AT BOTH SITES THROUGH 20Z. CEILINGS
EXPECTED TO REMAIN IN THE VFR CATEGORY WITH BASES 4K-6K FEET...ANY
MVFR CEILINGS WITH SHOWERS WILL BE SHORT LIVED. SUBSIDENCE IN THE
WAKE OF THE TROUGH WILL OVERSPREAD THE AREA THIS EVENING WITH
CLEARING SKIES. BOTH THE 07.12Z NAM AND 07.15Z RAP BUFKIT
SOUNDINGS DO SHOW WINDS TO REMAIN RATHER STRONG JUST ABOVE THE
SURFACE THROUGH THE OVERNIGHT HOURS. THUS DESPITE CLEARING SKIES
AND THE RECENT RAIN NOT EXPECTING ANY FOG FORMATION AT EITHER TAF
SITE.
DECENT MIXING LATER SATURDAY MORNING AND PRESSURE GRADIENT TO
REMAIN STRONG DID ADD SOME GUST TO NEAR 20 KNOTS AT BOTH KLSE AND
KRST AFTER 16Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
327 AM CDT FRI SEP 7 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...RABERDING
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1133 PM CDT THU SEP 6 2012
.UPDATE...
LIGHT PRECIPITATION FALLING FROM 10K TO 12K-FOOT CLOUD DECK NORTH
OF CWA WITH BRIEF 10SM LIGHT RAIN ON OBS. CONVECTION IN NW IOWA ON
NOSE OF 850 MB JET WILL BE MOVING TOWARD SRN WISCONSIN AS WEAK
850MB RIDGE AXIS SHIFTS EAST.
HRRR AND ARW IN AGREEMENT WITH 12Z ECMWF AND TAKE THIS COMPLEX
SOUTH INTO NRN IL...WITH 07/00Z NAM BRINGING LIGHT QPF AMOUNTS
INTO WRN CWA BETWEEN 09Z AND 12Z FRI BUT BULK OF PCPN OVER NRN IL.
00Z RUC AT 12Z FRI...AND NMM BRING PRECIP INTO THE SOUTH HALF OF
CWA...WITH NMM DROPPING 0.25 TO 0.50 INCH OF RAIN BY 15Z FRI. ALL
MODELS SHOW A BRIEF BREAK IN THE LATE MORNING/EARLY AFTERNOON THEN
FIRE PCPN BACK UP WITH DYNAMICS WITH PASSAGE OF WAVE.
&&
.AVIATION/06Z TAFS/...
KENW HAS MVFR/PATCHY IFR FOG WITH SKIES STILL CLEAR AND LIGHT
WIND. WILL KEEP VFR CONDITIONS OVER REMINDER OF TAF SITES AS HIGH
TO MID-LEVEL CLOUDS FILL IN AND LOWER WITH GRADUAL SATURATION.
SHOULD SEE SOME IMPROVEMENT IN VSBYS AT KENW WITH CLOUD BLANKET.
GIVEN CURRENT RADAR OBSERVATIONS AND MODEL TRENDS WILL HOLD PCPN
OFF AT KMSN UNTIL 09Z...AND THEN SPREAD IT EAST TO REACH EASTERN
TAF SITES BETWEEN 12Z AND 15Z. SOME EASING OF PCPN...IF NOT A
PERIOD OF DRY WEATHER IN THE LATE MORNING/EARLY AFTERNOON...THEN
PRECIPITATION FIRES UP AHEAD OF STRONG WAVE FOR LATE AFTERNOON AND
EVENING HOURS WITH MVFR CIGS AND VSBYS. CONDITIONS WILL IMPROVE
WITH PASSAGE OF 500 MB TROUGH AXIS...WITH PCPN ENDING AROUND 00Z SATURDAY
AT KMSN...BETWEEN 00Z AND 03Z AT KUES...AND BY 06Z AT KMKE AND KENW.
&&
.PREV DISCUSSION... /ISSUED 438 PM CDT THU SEP 6 2012/
SHORT TERM...
TONIGHT AND FRIDAY...FORECAST CONFIDENCE MEDIUM
MAIN FORECAST ISSUE IS THE TIMING...PLACEMENT...AND COVERAGE OF
PRECIP MOVING IN TONIGHT. IT LOOKS LIKE TWO AREAS OF RAIN WILL
FORM...ONE CLOSER TO THE 500 MB VORT MAX AND ONE WITH AN AREA OF
FRONTOGENESIS THAT WILL MOVE MAINLY TO OUR SOUTHWEST.
PRECIPITABLE WATER VALUES ARE ALMOST AT PLUS 2 STANDARD DEVIATIONS
IN THE SOUTH...SO IT LOOKS LIKE QPF WILL BE THE HIGHEST THERE.
MEANWHILE...VALUES IN THE NORTH AREN/T BAD EITHER... BUT ARE CLOSER
TO THE 75TH PERCENTILE. ALSO WORTH NOTING...UPPER DIVERGENCE LOOKS
THE BEST OVER THE FAR SOUTHERN AREA.
HAVE UPPED POPS ACROSS THOUGH CWA TO CATEGORICAL BASED ON THE
STRENGTH OF THE VORT MAX AND THE 250 MB JET. ALTHOUGH...THE JET
ISN/T QUITE AS BEEFY ON THE NEW NAM AS BEFORE...THERE IS GOOD
AGREEMENT AMONG THE MESO MODELS THAT EVERYWHERE WILL SEE RAIN...JUST
SOME AREAS JUST WON/T GET AS MUCH.
HIGH TEMPERATURES COULD STRUGGLE TOMORROW WITH CLOUD COVER AND
PRECIP...ALTHOUGH THERE COULD BE SOME CLEARING IN THE NORTHWEST IN
THE AFTERNOON THAT WOULD HELP A BIT.
FRIDAY NIGHT THROUGH SUNDAY...FORECAST CONFIDENCE MEDIUM TO HIGH
LGT RAIN COULD LINGER INTO FRI EVENING OVER SE WI AS THE UPPER
TROUGH AXIS WILL PASS THROUGH DURING THE EVENING. OVERALL
THOUGH...COLD AND DRY ADVECTION WILL BE UNDERWAY SO KEPT POPS
RELATIVELY LOW. NWLY FLOW AND COLD ADVECTION TO WEAKEN ON SAT WHILE
A JET STREAK AND SHORTWAVE TROUGH WILL DIVE SWD FROM CANADA INTO
LAKE HURON AND THE ERN GREAT LAKES. BELIEVE THIS FEATURE WILL REMAIN
FAR ENOUGH EAST TO MAINTAIN PARTLY CLOUDY SKIES AND DRY CONDITIONS
BASED ON A CONSENSUS OF MODELS. THE ECMWF IS FARTHER WEST OVER WI
AND MI WITH THESE FEATURES BUT IS AN OUTLIER. 500 HTS CONTINUE TO
RISE SAT NT AND SUN WITH SFC HIGH PRESSURE SETTLING OVER THE CENTRAL
USA INCLUDING WI. WITH DRY AIR OVER THE REGION...GOOD MIXING IS
EXPECTED THIS WEEKEND AND 925-850 MB TEMPS SUGGEST HIGH TEMPS IN THE
LOWER 70S FOR SAT AND LOWER TO MID 70S FOR SUN.
LONG TERM...MONDAY THROUGH THURSDAY...FORECAST CONFIDENCE MEDIUM
A STRONG POLAR TROUGH AND ASSOCIATED CYCLOGENESIS WILL PROGRESS
EWD ACROSS SRN CANADA NEXT WEEK. THIS WILL BRING BREEZY SSWLY
WINDS AND WARM ADVECTION FOR MON AND TUE. TEMPS WILL RISE INTO
THE 80S FOR TUE. THE SRN PERIPHERY OF THE COLD FRONT WILL BE WEAK
AND POSSIBLY STALL OVER SRN WI OR THE VICINITY FOR WED AND THU.
WILL KEEP FROPA DRY FOR NOW BUT THIS COULD CHANGE IN LATER
FORECASTS IF LOW LEVEL MOISTURE CAN ARRIVE FROM THE SOUTH.
AVIATION/00Z TAFS/...THE APPROACH OF A SURFACE FRONT AND MID LEVEL
TROUGH...ALONG WITH THE DEVELOPMENT OF AN UPPER JET...WILL BRING LOW
CLOUDS AND PRECIP TO THE AREA FROM MIDNIGHT TONIGHT THROUGH THE
MAJORITY OF THE REST OF THE PERIOD. EXPECTING TO SEE LOW CLOUDS AND
PRECIP BUILD INTO AREAS WEST OF MADISON AFTER MIDNIGHT...THEN SPREAD
EASTWARD DURING THE MORNING HOURS...AND DIMINISH WEST TO EAST FRIDAY
EVENING. LOOKING LIKE WE WILL SEE MVFR/IFR CONDITIONS DEVELOP IN
MADISON DURING THE FIRST PART OF THE MORNING...THEN IN EASTERN
LOCATIONS BY MID MORNING.
MARINE...
BRISK NORTH WINDS AND INCREASING WAVES MAY BRING SMALL CRAFT
ADVISORY CONDITIONS FRIDAY NIGHT AS A TIGHT PRESSURE GRADIENT
DEVELOPS BETWEEN DEPARTING LOW PRESSURE TO THE EAST AND HIGH
PRESSURE OVER THE GREAT PLAINS.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...REM
TONIGHT/FRIDAY AND AVIATION/MARINE...MEB
FRIDAY NIGHT THROUGH THURSDAY...GEHRING
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1238 AM EDT SUN SEP 9 2012
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 426 PM EDT SAT SEP 8 2012
MAIN FOCUS OF THE SHORT TERM IS THE STRONG SHORTWAVE SLIDING SSE
THROUGH NE MN AND WRN LK SUPERIOR AND THE ASSOCIATED SFC COLD FRONT.
AHEAD OF THIS SHORTWAVE...AREA OF SHOWERS HAS DROPPED OUT OF CANADA
THIS MORNING AND INTO FAR WRN UPPER MI. EXPECT THESE SHOWERS TO
CONTINUE TO SLIDE TO THE SE OVER THE COUNTIES NEAR THE WI BORDER
THROUGH THE REST OF THIS AFTN...ASSOCIATED WITH THE H850-500
Q-VECTOR CONV. BEHIND THIS INITIAL AREAS OF SHOWERS AND THE
FRONT...SCATTERED SHOWERS HAVE DEVELOPED UNDER THE CENTER OF THE
SHORTWAVE AND ASSOCIATED WITH AREA OF STEEP MID LVL LAPSE RATES.
THESE SHOWERS SHOULD CONTINUE TO THE SSE AND LARGELY MISS THE
CWA...BUT COULD SEE SOME SCATTERED SHOWERS OVER THE WEST UNTIL
DIURNAL HEATING IS LOST AND THE SHORTWAVE SLIDES S OF THE CWA.
ATTENTION THEN TURNS TO POTENTIAL LK ENHANCED SHOWERS AND CLOUDS FOR
TONIGHT. RUC ANALYSIS IS SHOWING THAT H850 TEMPS HAVE WARMED A
DEGREE OR TWO FROM THIS MORNING...TOWARDS 6-7C OVER THE WEST AHEAD
OF THE SHORTWAVE. ONCE THIS WAVE AND THE SFC FRONT SLIDE SE OF THE
AREA...EXPECT H850 TEMPS TO FALL TOWARDS 5C BY THIS EVENING AND THEN
4C BY 12Z SUN. WITH LK SUPERIOR TEMPS IN THE 17-21C RANGE...THIS
SHOULD PROVIDE DECENT DELTA-T VALUES FOR LK ENHANCED SHOWERS/CLOUDS.
THE MAIN QUESTION FOR TONIGHT INTO SUN MORNING IS THE AMNT OF
MOISTURE AND IT/S LOCATION. WITH THE TRACK OF THE SHORTWAVE AND
MOISTURE UPSTREAM INTO ONTARIO...EXPECT FAR WRN UPPER MI TO SEE THE
BEST OPPORTUNITY FOR LK ENHANCED SHOWERS UNDER THE NRLY BL FLOW.
THAT AREA WILL BE AIDED BY COASTAL CONVERGENCE AND UPSLOPE FLOW...SO
HAVE HIGH END CHANCE POPS THROUGH MUCH OF THE NIGHT. WITH A SLIGHT
DELAY TO THE COLDEST TEMPS...MAY SEE A SHORT BREAK IN THE SHOWERS
AFTER THE SUN GOES DOWN AND BEFORE THE COLD AIR ARRIVES. FARTHER NE
IS A LITTLE MORE UNCERTAIN. MODELS SHOWING H850-700 DRY AIR DROPPING
S FROM CNTRL ONTARIO AND OVER CNTRL/ERN LK SUPERIOR THIS EVENING AND
OVER CNTRL/ERN UPPER MI OVERNIGHT. WITH THE LACK OF CU THAT HAS
DEVELOPED NE OF THUNDER BAY...THAT SEEMS FAIRLY REASONABLE.
BUT...H925-850 MOISTURE AND STEEP LAPSE RATES OVER LK SUPERIOR WITH
THE NRLY FLOW SHOULD STILL PRODUCE ISOLATED TO POTENTIALLY SCATTERED
LK ENHANCED SHOWERS OVER THE NCNTRL CWA WITH THE LIMITED CLOUD DEPTH
KEEPING THEM LIGHT. ALL OF THESE SHOWERS MAY BE HELPED BY A
SECONDARY SHORTWAVE FROM NW ONTARIO MOVING THROUGH OVERNIGHT.
FOR TOMORROW...WITH LINGERING LLVL MOISTURE AND 3-4C H850
TEMPS...THE NNW WIND FAVORED LOCATIONS SHOULD SEE PARTLY/MOSTLY
CLOUDY SKIES THROUGH THE MORNING HOURS. STILL LINGERED LIGHT SHOWERS
THROUGH THE MORNING...BUT LIMITED MOISTURE DEPTH SUPPORTS ONLY
HAVING SLIGHT CHANCES. OVER THE CNTRL/EAST IN THE AFTN...MOISTURE
THAT IS CURRENTLY OVER NW ONTARIO SHOULD DROP OVER THE ERN LK AND
WITH THE COLD TEMPS REINFORCE THE CLOUD DECK. NCEP WRF NMM/ARW RUNS
HAVE SHOWN THE POTENTIAL FOR SHOWERS WITH THIS WAVE...BUT CONCERNED
DRIER AIR ALOFT WILL KEEP CLOUDS FROM DEVELOPING TOO MUCH. FARTHER
WEST...HIGH PRESSURE BUILDING IN UNDER THE UPPER RIDGING WILL HELP
BRING DRIER AIR INTO THE AREA AND DECREASE THE CLOUDS DURING THE
AFTN AND LEAD TO CLEARING AFTER 21Z.
FINALLY...WITH THE NORTHERLY WINDS CREATING 3-5FT WAVES
TOMORROW...EXPECT A MODERATE TO HIGH RISK OF RIP CURRENTS TO
CONTINUE TOMORROW.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 426 PM EDT SAT SEP 8 2012
MEDIUM RANGE GUIDANCE CONTINUES TO BE IN GENERAL AGREEMENT ON THE
BIG PICTURE OVER THE NEXT 7 DAYS AS IT PERTAINS TO UPPER MI. AFTER
THIS WEEKENDS TROF...PATTERN WILL BECOME MORE PROGRESSIVE NEXT WEEK.
THE TROF DOMINATING THE GREAT LAKES THIS WEEKEND WILL BE FOLLOWED BY
RIDGING EARLY IN THE WEEK...A TROF FOR THE MID/LATE PORTION OF THE
WEEK...AND ANOTHER TROF LATE NEXT WEEKEND. THE EVOLUTION/STRUCTURE
OF THE MID/LATE WEEK TROF REMAINS THE MAIN AREA OF MODEL
DISAGREEMENT. WITH A PROGRESSIVE PATTERN...TEMPS WILL SHOW A FAIR
AMOUNT OF VARIATION OVER THE NEXT 7 DAYS. TEMPS A LITTLE BLO NORMAL
THRU THE WEEKEND WITH TROFFING OVER THE GREAT LAKES WILL TRANSITION
TO STRONG WARMING/ABOVE NORMAL TEMPS EARLY IN THE WEEK AHEAD OF THE
NEXT APPROACHING TROF. GRADUAL COOLING WILL OCCUR MIDWEEK...LEADING
TO TEMPS AROUND NORMAL LATE IN THE WORK WEEK AS MID/UPPER LEVEL
TROF PASSES. TEMPS WILL THEN BEGIN TO REBOUND FOR THE START OF NEXT
WEEKEND. AS FOR PCPN...THIS WILL BE AN OVERALL DRY PERIOD DUE TO
LACK OF GULF MOISTURE TRANSPORT TO THE UPPER LAKES AND DUE TO MAIN
FORCING PASSING N OF THE AREA WHEN SHORTWAVES PASS.
BEGINNING SUN NIGHT...WITH SFC HIGH PRES RIDGE PASSING ACROSS THE
AREA...CLR SKIES AND PRECIPITABLE WATER 45-65PCT OF NORMAL...A GOOD
RADIATIONAL COOLING NIGHT IS EXPECTED. MINS ON THE LOW SIDE OF AVBL
GUIDANCE LOOK ON TRACK. TRADITIONAL INTERIOR COLD SPOTS SHOULD DROP
TO THE UPPER...POSSIBLY MID...30S. MIGHT SEE A LITTLE FROST.
AS MID LEVEL RIDGE SHIFTS TO THE UPPER LAKES MON...WAA WILL BE
UNDERWAY. LOW-LEVEL JET/STRONGEST PUSH OF WARMING IS WELL TO THE NNW
MON...SO PCPN IS NOT A CONCERN. TEMPS SHOULD REBOUND INTO THE 70S
UNDER WAA PATTERN.
AS THE MID LEVEL RIDGE SHIFTS E TUE AND NEXT TROF BEGINS TO MOVE OUT
OVER THE NRN PLAINS...850MB THERMAL RIDGE (TEMPS OF 16-19C) WILL
TRANSLATE OVER THE AREA. ALTHOUGH THERE REMAINS SOME CONCERN WITH
MID/HIGH CLOUD COVERAGE TUE...THERMAL RIDGE AND BREEZY S-SW WINDS
WILL LEAD TO A WARM DAY FOR EARLY/MID SEPT...ESPECIALLY OVER THE W
HALF. WILL STAY WITH HIGH TEMPS MAINLY LOW/MID 80S...ABOVE ALL
GUIDANCE IN MOST AREAS. NOT TOTALLY OUT OF THE QUESTION THAT SOME OF
THE DOWNSLOPE AREAS OVER THE W TOWARD LAKE SUPERIOR COULD FLIRT WITH
90F IF THE DAY ENDS UP SUNNY. COOLER READINGS WILL BE OVER THE E
WITH FLOW UP LAKE MICHIGAN. WITH LOW-LEVEL JET TRANSLATING ACROSS
THE AREA...THERE IS A VERY SMALL POTENTIAL FOR SOME CONVECTION...BUT
LACK OF BETTER MOISTURE MINIMIZES THE POTENTIAL.
MEDIUM RANGE GUIDANCE HAS CONTINUED TO SLOW DOWN SLIGHTLY THE COLD
FRONT ASSOCIATED WITH THE INCOMING MID LEVEL TROF MIDWEEK. IT NOW
APPEARS FRONT WILL BE CROSSING THE AREA DURING THE DAY WED. WITH
BEST DEEP LAYER FORCING PASSING WELL TO THE N AND WITH A LACK OF A
GOOD GULF MOISTURE CONNECTION...THERE SHOULDN`T BE MUCH PCPN
ASSOCIATED WITH THE FRONT. HOWEVER...WITH THE UPPER TROF TAKING ON A
POSITIVE TILT FROM HUDSON BAY TO THE NRN PLAINS THRU THU...THE
SUPPORTING SW-NE ORIENTED UPPER JET WILL SLOWLY TRANSLATE EASTWARD.
AS IT DOES...RIGHT ENTRANCE UPPER DIVERGENCE WILL BEGIN TO OVERLAY
THE LOW-LEVEL FRONT...LIKELY LEADING TO A RIBBON SHRA EVENTUALLY
DEVELOPING ALONG/BEHIND SFC FRONT AS SUGGESTED BY THE
GFS/ECMWF/GLOBAL GEM. THUS...PLAN TO MAINTAIN SCHC POPS OVER THE FAR
W LATE TUE NIGHT INTO WED WITH SCHC POPS EXPANDING INTO THE CNTRL
WED AND THEN CHC POPS OVER THE E HALF WED NIGHT. INSTABILITY IS VERY
LIMITED...SO POTENTIAL OF THUNDER IS MINIMAL. LINGERED SCHC POPS
OVER ALL BUT THE FAR W THU GIVEN MODEL TRENDS...BUT MAY NEED TO
INCREASE THU POPS TO CHC IF CONSISTENCY DEVELOPS FOR SLOW FRONTAL
MOVEMENT AND AN INCREASED POST FRONTAL PCPN BAND WITH TIME DUE TO
UPPER JET.
SINCE YESTERDAY`S RUNS...GFS/ECMWF HAVE TRENDED COOLER FOR FRI AS
THE MID/UPPER LEVEL TROF PASSES (850MB TEMPS 3-5C TO START THE DAY).
AS A RESULT...TEMPS WILL BE BACK AROUND NORMAL MID SEPT VALUES (60S
FOR HIGHS). MIGHT BE SOME LAKE EFFECT -SHRA FRI MORNING IN THE
CHILLY NW FLOW. OTHERWISE...DRY WEATHER IS EXPECTED FRI. HOWEVER...
IT IS NOTED THAT THE 00Z GFS AND NOW THE 12Z ECMWF SHOW ENERGY IN
THE SRN PORTION OF PASSING TROF SEPARATING OUT AND LEADING TO A MID
LEVEL LOW TRACKING INTO THE UPPER LAKES FRI INTO EARLY SAT. GIVEN
THE VERY INCONSISTENT SIGNAL...WILL IGNORE THIS IDEA FOR NOW. WILL
BE SOMETHING TO KEEP IN MIND WHICH MAY CHANGE THE CURRENT DRY FCST
TO A POSSIBLE GOOD SOAKING. IN THE ABSENCE OF THE POSSIBLE MID LEVEL
LOW...DRY WEATHER/WARMING IS EXPECTED SAT AS WEAK MID LEVEL RIDGE
ARRIVES. NEXT SHORTWAVE TROF SHOULD ARRIVE SUN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1237 AM EDT SUN SEP 9 2012
COLDER AIR MOVING IN BEHIND A FRONT WILL BRING THE CHANCE FOR SOME
LAKE EFFECT CLOUDS AND RAIN SHOWERS. EXPECT THE BEST CHANCE FOR
LOWER CIGS AND SHRA AT KIWD...CLOSER TO THE MORE FAVORABLE LOW LEVEL
MOISTURE. KSAW MAY ALSO SEE A PERIOD OF LOWER CIGS BUT CONFIDENCE IS
LOWER...SO LEFT WITH CIGS JUST ABOVE MVFR. DRIER AIR AND A LESS
FAVORABLE FETCH SHOULD MAINTAIN VFR CONDITIONS AT CMX. AS DRIER AIR
MOVES IN EXPECT ANY REMAINING BKN CIGS TO DISSIPATE BY LATE SUNDAY
MORNING.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 426 PM EDT SAT SEP 8 2012
A SFC TROUGH DROPPING SE ACROSS LAKE SUPERIOR THIS EVENING WILL
BRING A REINFORCING SHOT OF COLD AIR AND STRENGTHEN THE NNW WINDS
ACROSS LAKE SUPERIOR. THE HIGHEST GUSTS...TO 30KTS...WILL BE SEEN
OVER FAR WRN LK SUPERIOR...WILL THE REST OF THE LAKE WILL SEE
15-25KTS TONIGHT INTO TOMORROW. HIGH PRESSURE WILL BUILD OVER THE
UPPER GREAT LAKES TOMORROW AND LEAD TO WEAKENING WINDS SUN AFTN AND
SUNDAY NIGHT. AS THE HIGH QUICKLY SHIFTS TO THE LOWER GREAT LAKES
ON MONDAY...SOUTHERLY WINDS WILL INCREASE AND PRODUCE A PERSISTENT
PERIOD OF 15-25KT WINDS THROUGH TUESDAY NIGHT WHEN A COLD FRONT
PUSHES ACROSS LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...JLB
MARINE...SRF
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1213 AM EDT SUN SEP 9 2012
.SYNOPSIS...
ISSUED AT 252 PM EDT SAT SEP 8 2012
EXPECT SHOWERS AND ISOLATED THUNDERSTORMS NEAR LAKE MICHIGAN
TONIGHT. THAT ACTIVITY WILL DIMINISH BY MID MORNING SUNDAY.
OTHERWISE EXPECT COOLER WEATHER TO PREVAIL INTO THE BEGINNING OF
THE WEEK. A WARMING TREND WILL BEGIN BY TUESDAY THAT WILL LAST
INTO THE END OF THE WEEK.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 252 PM EDT SAT SEP 8 2012
THE PRIMARY FORECAST CONCERN IS THE AREA OF SHOWERS MOVING
SOUTHEAST FROM WESTERN UPPER MICHIGAN AND HOW IT WILL IMPACT
SOUTHWEST LOWER MICHIGAN OVERNIGHT AS IT MOVES THROUGH.
OTHERWISE...I EXPECT TEMPERATURES TO FALL INTO THE 30S NEAR ROUTE
10 EAST OF THE LAKE SHORE SUNDAY NIGHT. AN EARLY TASTE OF FALL FOR
SURE.
A STRONG SHORTWAVE... WELL DEFINED ON THE WATER VAPOR LOOPS...
WILL CONTINUE TO DROP SOUTHEAST CROSSING SOUTHWEST LOWER MICHIGAN
DURING THE EARLY EVENING HOURS. THERE IS A 130 KNOT JET EXIT
REGION THAT CROSSES SOUTHERN LAKE MICHIGAN JUST BEFORE MIDNIGHT
ASSOCIATED WITH FEATURE. THIS JET CORE IS ROTATING AROUND THE BASE
OF THE CLOSED 300 MB LOW THAT IS ALSO ASSOCIATED WITH THIS
FEATURE. BOTH THE NAM12 AND HRRR RUC SUGGEST A MESO-LOW FEATURE
WILL DEVELOP ON THE EAST SIDE (MICHIGAN SIDE)OF THE LAKE AN TRACK
SOUTH THROUGH THE NIGHT ENHANCING THE CONVERGENCE OVER THE LAKE.
GIVEN THE 850 MB TO LAKE TEMP DIFFERENCE IS NEAR 15C. BUFKIT SHOWS
THE EQUILIBRIUM LEVEL OVERNIGHT WILL APPROACH 30000 FT AGL WITH
NEARLY 2000 J/KG OF LAKE INDUCED CAPE. I AM THINKING THIS IS
ENOUGH FOR SCT TO ISOLATED THUNDERSTORMS. LOCALLY HEAVY SHOWERS
SHOULD BE EXPECTED. THAT THINKING IS CONFIRMED BY THE SPC SREF.
NEARLY ALL OF THIS WILL MOSTLY BE OVER LAKE MICHIGAN AND WEST OF
US-131 WHERE THE LAKE INDUCED INSTABILITY WILL BE A FACTOR. INLAND
OF THAT EXPECT PARTLY CLOUDY SKIES WITH POSSIBLY A PASSING SHOWER
AS THE UPPER WAVE MOVE THROUGH.
ONCE THIS FEATURE EXITS THE AREA MID TO LATE MORNING SUNDAY THE
UPPER RIDGE BUILDS IN THROUGH TUESDAY. THERE WILL BE ENOUGH
INSTABILITY YET FOR ISOLATED SHOWERS SOUTH OF ROUTE 10 AND EAST OF
US-131 SUNDAY AFTERNOON SINCE THE UPPER JET WILL NOT BE EAST OF
THERE YET.
SUNDAY NIGHT WITH SURFACE HIGH PRESSURE OVER THE AREA WINDS WILL
BE LIGHT AND SKIES CLEAR. I EXPECT LOWS IN THE MID 30S OVER OUR NE
CWA AND LOWER TO MID 40S ELSEWHERE. A SLOW WARMING TREND FOLLOWS
THEN WITH MOSTLY CLEAR SKIES THROUGH TUESDAY NIGHT.
.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 305 PM EDT SAT SEP 8 2012
WE/LL START TO WARM UP AGAIN TUESDAY AS THE HIGH MOVES TOWARD NEW
ENGLAND. THE NEXT COLD FRONT WILL LIKELY MOVE ACROSS THE CWA
THURSDAY NIGHT OR FRIDAY. INSTABILITY DOESN/T LOOK VERY IMPRESSIVE
WITH THIS NOR DO THE MOISTURE TRANSPORT VECTORS. AS A RESULT I
CAN/T SEE MUCH MORE THAN SLIGHT CHC POPS AT THIS POINT. THERE IS A
COMPACT SHORT WAVE ASSOCIATED WITH THIS AND THAT MAY BOOST PCPN
CHANCES INTO SATURDAY...BUT GIVEN THE SFC RIDGING MOVING IN AT
THAT POINT...PCPN AMOUNTS AND CHANCES LOOK MEAGER.
TEMPS WILL CLIMB TO AROUND 80 PRIOR TO FROPA AND THAN BACK INTO THE
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1213 AM EDT SUN SEP 9 2012
DESPITE SCATTERED RAIN SHOWERS MOVING THROUGH... CONDITIONS ARE
EXPECTED TO REMAIN PREDOMINATELY VFR TONIGHT AND SUNDAY MORNING
WITH CLOUD BASES MOSTLY ABV 4K FT. TSTMS ARE EXPECTED TO REMAIN
MOSTLY OVER LK MI SOUTH OF MKG. SCATTERED CLOUDS ARE EXPECTED
SUNDAY AFTERNOON BEHIND THE FRONT.
&&
.MARINE...
ISSUED AT 633 PM EDT SAT SEP 8 2012
ISSUED ANOTHER SCA FOR THE NRN ZONE. GUSTY WINDS EXPECTED WITH THE
NEXT COLD FRONT CURRENTLY MOVING ACROSS WISCONSIN.
&&
.HYDROLOGY...
ISSUED AT 252 PM EDT SAT SEP 8 2012
RIVERS WILL CONTINUE TO FALL SLOWLY THROUGH THIS COMING WEEK AS
IT IS EXPECTED TO BE DRY MOST OF THIS COMING WEEK. ANY RAINFALL
WE GET TONIGHT WILL ONLY BE NEAR THE LAKE SHORE AND THAT WILL NOT
IMPACT MOST OF RIVERS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
LMZ847>849.
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR LMZ844>846.
&&
$$
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...93
AVIATION...MEADE
HYDROLOGY...WDM
MARINE...93
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
309 AM EDT SUN SEP 9 2012
.SYNOPSIS...
A STRONG COLD FRONT WILL MOVE OFFSHORE THIS MORNING. STRONG HIGH
PRESSURE WILL BUILD OVER MUCH OF THE EASTERN SEABOARD BY LATE
TODAY AND CONTINUE IN PLACE THROUGH LATE NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 3 AM SUNDAY...THE HEAVY CONVECTIVE ACTIVITY HAS MOVED WELL
OFFSHORE AND WILL REMOVE THUNDER FROM THE FORECAST FOR THE NEXT
UPDATE. PATCHY LIGHT RAIN WILL PERSIST INTO THE MORNING HOURS.
EACH SUCCESSIVE RUN OF THE RAP SHOWS PRECIPITATION ENDING
EARLIER...WITH THE LATEST RUN SHOWING ALL PRECIP OFFSHORE BY 15Z
THIS MORNING. WILL KEEP 40 TO 50 PCT POPS UNTIL ABOUT MIDDAY. EXPECT
IT TO TAKE A BIT LONGER FOR SKIES TO CLEAR AS AXIS OF MUCH LOWER
PRECIPITABLE WATER DOES NOT REACH THE COAST UNTIL ABOUT 21Z...SO
THINK THE MAJORITY OF THE WAY WILL BE ON THE CLOUDY SIDE. THE
CLOUDS...COUPLED WITH DECENT LOW- LEVEL CAA...WILL HOLD MAX
TEMPERATURES IN THE MIDDLE AND UPPER 70S FOR ALL AREAS TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
AS OF 305 AM SUNDAY...MUCH DRIER AND COOLER EARLY FALL-LIKE AIR
WILL FILTER INTO THE REGION IN EARNEST TONIGHT. SKIES SHOULD BE
CLEAR BY SUNSET IN ALL AREAS WITH MINIMUM TEMPERATURES TONIGHT IN
THE UPPER 50S INLAND RANGING TO THE LOWER 60S ALONG THE CRYSTAL
COAST AND MIDDLE 60S ALONG THE OUTER BANKS.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
AS OF 3 AM SUN...EXTENDED STRETCH OF NICE WEATHER IN STORE. HIGH
PRESSURE CENTERED IN THE OHIO VALLEY MONDAY WILL SHIFT TO THE MID-
ATLANTIC ON THURSDAY...THEN OFFSHORE NEXT WEEKEND. LIGHT NORTH
FLOW MONDAY WILL VEER TO NORTHEAST BY LATE IN THE WEEK. ECMWF
SHOWING A WEAK UPPER LOW FORMING OFFSHORE BY LATE IN THE
WEEK...BRINGING A SLIGHT CHANCE OF SHOWERS TO THE AREA BY
SATURDAY.
&&
.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
SHORT TERM /TODAY AND TONIGHT/...
AS OF 305 AM SUNDAY...EXPECT PERIODS OF MVFR/IFR CEILINGS THROUGH
MOST OF THE DAY TODAY WITH SOME PATCHY LIGHT SHOWERS UNTIL ABOUT
MIDDAY. DRIER AND COOLER AIR SHOULD BEGIN TO OVERSPREAD THE AREA
BY TONIGHT WITH VFR CONDITIONS BY SUNSET AND THRU THE OVERNIGHT
HOURS.
LONG TERM /MON THROUGH THU/
AS OF 3 AM SUN...EXTENDED PERIOD OF EXCELLENT FLYING WEATHER WITH
HIGH PRESSURE CENTERED OVER THE REGION. MOSTLY CLEAR SKIES. LIGHT
NORTH WINDS MONDAY AND TUESDAY...VEERING TO NORTHEAST FOR
WEDNESDAY AND THURSDAY.
&&
.MARINE...
SHORT TERM /TODAY AND TONIGHT/...
AS OF 310 AM SUNDAY...AS ANTICIPATED...GETTING A BIT OF A SURGE
BEHIND STRONG COLD FRONT WHICH WILL GRADUALLY WORKING ITS WAY
OFFSHORE EARLY THIS MORNING. THINK THE MAXIMUM WINDS IN THE SURGE
WILL HOLD AT 20 KNOTS IN GUSTS. SEAS CONTINUE AT 4 TO 6 FEET WITH
LONG PERIOD (13 SECOND) SWELLS UP AND DOWN THE NC COAST. THIS WILL
LEAD TO ANOTHER DAY OF ELEVATED RIP CURRENT THREAT FOR TODAY.
AS OF 3 AM SUN...LATEST RUN OF THE MAJOR MODELS CONTINUE IN VERY
CLOSE AGREEMENT AND USED AN OVERALL BLEND FOR THE WINDS. BASED ON
LATEST RUNS OF WAVEWATCH AND IN-HOUSE SWAN THE SMALL CRAFT
HEADLINES HAVE BEEN TRIMMED BACK TO END EARLIER...06Z TUESDAY
SOUTH OF OCRACOKE AND 00Z WEDNESDAY NORTH OF OCRACOKE. HIGH
PRESSURE CENTERED IN THE OHIO VALLEY MONDAY WILL SHIFT TO THE MID-
ATLANTIC STATES ON THURSDAY. LIGHT NORTHEAST FLOW MONDAY AND
TUESDAY WILL VEER TO NORTHEAST FOR WEDNESDAY AND THURSDAY. LONG
PERIOD EAST SWELL OF 12-13 SECONDS MONDAY WILL SUBSIDE TO 10
SECONDS BY THURSDAY.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT TUESDAY FOR AMZ150-152-154.
SMALL CRAFT ADVISORY UNTIL 2 AM EDT TUESDAY FOR AMZ156-158.
&&
$$
SYNOPSIS...CTC
NEAR TERM...CTC
SHORT TERM...CTC
LONG TERM...HSA
AVIATION...CTC/HSA
MARINE...CTC/HSA
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
334 AM CDT SUN SEP 9 2012
.TODAY AND TONIGHT...FORECAST CONFIDENCE MEDIUM TO HIGH.
SCATTERED SHOWERS DEVELOPING IN REGION OF LAND BREEZE CONVERGENCE
OVER MID-LAKE IN WAKE OF DEPARTING SHORT WAVE. FORECAST SOUNDINGS
SHOW FAVORABLE DELTA T AND NORTH-NORTHEAST FLOW DEVELOPING BELOW 5K
FT...WITH NAM...GFS AND RUC 1000-900MB LAYER WIND/CONVERGENCE
FORECASTS INDICATING POTENTIAL OF SHOWERS BRUSHING THE SHORE BETWEEN
12Z AND 18Z. WILL KEEP SOME POPS ALONG THE SHORE FROM MILWAUKEE
SOUTH.
OTHERWISE DRY TROUGH THE PERIOD WITH UPPER RIDGING AND SURFACE HIGH
PRESSURE BUILDING OVER THE REGION...WITH COOL TEMPERATURES. 925MB
TEMPERATURES SUPPORT DAYTIME HIGHS IN THE LOW TO MID 70S WEST TO
AROUND 70 EAST. GOOD RADIATIONAL CONDITIONS TONIGHT WILL ALLOW LOWS
TO FALL INTO THE MID 40S AWAY FROM THE LAKE.
MONDAY THROUGH WEDNESDAY - CONFIDENCE...MEDIUM
BROAD 500 MILLIBAR ANTICYCLONIC FLOW ACROSS THE CWA THIS PERIOD.
SURFACE/850 HIGHS TO THE EAST. A WARMER SOUTHERLY REGIME KICKS IN.
500 MILLIBAR FLOW BECOMES MORE SOUTHWEST ON WEDNESDAY THOUGH BEST
FORCING...BOTH ALOFT AND IN THE LOW LEVELS...REMAINS TO THE NORTH
AND NORTHWEST OF THE CWA. 925 TEMPS SLOW TO RESPOND MONDAY...BUT A
SLIGHT WARMING NOTED. A MORE PRONOUNCED WARMING ON TUESDAY WITH 925
TEMPS BACK TO THE LOW 20S CELSIUS...WITH POSSIBLE MID 20S WEDNESDAY
WITH SOUTHWEST WINDS MAINTAINING THE WARM AIRMASS AHEAD OF THE
FRONT. SO TEMPS WELL INTO THE
WEDNESDAY NIGHT AND THURSDAY - CONFIDENCE...LOW
SURFACE BOUNDARY AND 850 BAROCLINIC ZONE SAGS INTO SRN WI THIS
PERIOD WITH PRECIP CHANCES INCREASING. 500 MILLIBAR FLOW BECOMES
SOUTHWEST WITH INCREASED POTENTIAL FOR RIPPLES RIDING NORTHEAST IN
THE FLOW. MAIN TROUGH AXIS BACK IN MINNESOTA WITH ECMWF HAVING TWO
CONSECUTIVE RUNS OF SHOWING A MUCH MORE POTENT VORT CENTER.
THURSDAY NIGHT AND FRIDAY - CONFIDENCE...LOW
12Z AND 00Z ECMWF SHOWING A RATHER SIGNIFICANT SHORTWAVE/VORT MAX
CRASHING INTO THE AREA WITH ABUNDANT QPF. SURFACE LOW PRESSURE WOULD
TRACK SOUTH OF THE AREA WITH A SIGGY RAIN EVENT WITH DEF ZONE PRECIP
SHIELD ACROSS MUCH OF WI. THE GFS AND GEM ARE WEAKER WITH THE UPPER
WAVE CROSSING WI AND IMPLY DRYING WORKING IN WITH HIGH PRESSURE.
LOTS TO SORT OUT YET WITH THIS SYSTEM...BUT THE ECMWF HAS SHOWN SOME
CONSISTENCY YET THERE IS SOME CONSENSUS BETWEEN THE GEM AND GFS.
SATURDAY - CONFIDENCE...LOW TO MEDIUM
WHILE THE DETAILS BETWEEN THE MODELS VARY THE CONSENSUS IS FOR GOING
WITH A DRY FORECAST AS SYSTEM SHIFTS AWAY.
&&
.AVIATION/12Z TAFS/...PATCHY MVFR STRATUS AND FOG WILL CLEAR AROUND OR
SHORTLY AFTER ISSUANCE...WITH VFR CONDITIONS THROUGH THE PERIOD.
NORTH WINDS WILL BE GUSTY FOR A TIME AT EASTERN TAF SITES THIS
MORNING...THEN WEAKEN THIS AFTERNOON AS THEY SHIFT NORTHEAST.WILL
HAVE TO WATCH FOR PATCHY FOG AT KENW TONIGHT...WITH DEW POINTS
HOLDING UP A BIT MORE THAN INLAND AREAS...AND LAND BREEZE NOT AS
SIGNIFICANT A FACTOR AS AT KMKE.
&&
.MARINE...WILL NOT ISSUE A SMALL CRAFT ADVISORY AT THIS TIME...EVEN
THOUGH WINDS BECOME FAVORABLE FOR A TIME AS THEY SHIFT FROM OFFSHORE
EARLY TO THE NORTH...AND THEN NORTHEAST THROUGH THE MORNING INTO THE
EARLY AFTERNOON. GRADIENT WEAKENS WITH THE MORE FAVORABLE FETCH
REDUCING WIND SPEEDS WHICH WILL LIMIT WAVE HEIGHTS.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...REM
MONDAY THROUGH SATURDAY...COLLAR
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
737 AM EDT SUN SEP 9 2012
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL SWING THROUGH THE AREA TODAY. AT
THE SURFACE A TROUGH OF LOW PRESSURE WILL LINGER IN THE AREA.
MONDAY THROUGH WEDNESDAY...HIGH PRESSURE WILL DOMINATE ACROSS THE
REGION.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE...UPPER VORTEX MOVING ACROSS NORTHERN INDIANA HOWEVER MUCH
OF THE RAIN ASSOCIATED WITH THIS HAS DIMINISHED OVER THE PAST
COUPLE HOURS. HRRR ACTUALLY DOES NOT REDEVELOP THE PRECIP FAVORING
INSTEAD MORE SHOWERS ALONG THE NORTHEAST LAKESHORE ESPECIALLY
THROUGH THE MORNING...AND SPOTTY SHOWERS THIS AFTERNOON. WILL DROP
THE LIKELY POP WEST THIS MORNING AND LOWER TO 30-40%.
ELSEWHERE...ALONG THE EAST LAKESHORE...RAIN HAS DIMINISHED QUITE A
BIT. STILL THINK THERE IS MORE TO COME BUT WILL DROP CAT POPS BACK
TO LIKELY. WILL ALSO RESTRICT THE MENTION OF THUNDER TO THE EAST
LAKESHORE WITH THE INSTABILITY OFF THE LAKE. NO OTHER CHANGES.
ORIGINAL...WE ARE MOVING INTO THE SEASON FOR LAKE EFFECT RAINS
AS INCREASINGLY FREQUENT SHOTS OF COLD AIR MOVE ACROSS THE WARM
LAKE ERIE WATERS. MODELS SHOW A SHARP UPPER TROF SWINGING THROUGH
THE GREAT LAKES DURING THE DAY WHILE THE WATER VAPOR LOOP SHOWS A
VIGOROUS UPPER VORTEX DROPPING INTO THE BASE OF THE TROF ACROSS
SRN LWR MI. 850MB TEMPS ARE FORECAST TO BE 6 TO 7C CURRENTLY WHICH
YIELDS CAPES OF 1000-1300J/KG WITH RESPECT TO THE LAKE. RADAR
SHOWING SHOWERS AND THUNDERSTORMS DEVELOPING JUST OFF SHORE AND
MOVING ACROSS LAKE COUNTY AND THEN NORTHEAST ACROSS ASHTABULA AND
ERIE COUNTIES. DRIVING FLOW FOR LAKE EFFECT WILL BE CHANGEABLE
TODAY WITH THE SYSTEM MOVING THROUGH HOWEVER WILL CONTINUE WITH
CATEGORICAL POPS EAST OF CLEVELAND FOR THE MORNING AND THEN DROP
BACK TO CHANCE POPS BY EVENING. ELSEWHERE...UPPER LEVEL VORTEX TO
OUR WEST HAS SHOWERS AND THUNDERSTORMS ASSOCIATED WITH IT...NOW
MOVING INTO NERN INDIANA AND SOUTH CENTRAL MI. EXPECT THIS TO
MAINTAIN ITSELF AND MOVE ACROSS THE REGION FROM WEST TO EAST
THROUGH THE MORNING. CURRENTLY HAVE HIGH CHANCE IN THE GRIDS AND
MAY BUMP THAT TO LIKELY AT LEAST FOR THE MORNING.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
WILL NEED TO HANG ONTO LOW CHANCE/SLIGHT CHANCE POPS NORTHEAST
TONIGHT AND MONDAY GIVEN 850MB TEMPS REMAINING 6 TO 8C THROUGH THE
PERIOD. NEGATIVE INFLUENCES WOULD BE DRIER AIR MOVING IN AS WELL
AS BUILDING HIGH PRESSURE. AFTER THAT HOWEVER THE BALANCE OF THE
SHORT TERM WILL HAVE HIGH PRESSURE ACROSS THE REGION WITH SLOWLY
MODERATING TEMPS INTO MID WEEK AS THE HIGH DRIFTS TO OUR EAST.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
LITTLE CHANGE TO THE FORECAST FOR THE END OF THE WEEK. HIGH PRESSURE
THURSDAY AND TEMPS SEASONABLE. THERE ARE STILL HINTS THAT THE
WEEKEND FRONT WILL BE A LITTLE SLOW. HAVE CONTINUED THE PRECIP
CHANCES FROM FRIDAY NIGHT INTO SATURDAY. WITH THE BETTER CHANCES
THAT THE FRONT WILL HAVE PASSED OR BE OVERHEAD SATURDAY...HAVE
SLIGHTLY COOLER TEMPS...LOWER 70S WITH SOME LINGERING SHOWERS.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
UPPER TROUGH AXIS ON WATER VAPOR IMAGERY MAKING ITS WAY TO NW OHIO
EARLY THIS MORNING. THE SHOWER ACTIVITY WITH IT HAS DIMINISHED
SOMEWHAT...BUT EXPECT SOME ISOLATED TO SCATTERED SHOWER ACTIVITY
TO POP AGAIN FOR THIS AFTERNOON. BEST CHANCES WILL BE ACROSS THE
CENTRAL AND EAST...WITH THUNDER POSSIBLE ACROSS THE SNOWBELT. VFR
OUTSIDE OF SHOWERS. MVFR WITH PERIODS OF IFR WITHIN THE HEAVIER
SHOWERS. WITH RELATIVELY LOW CHANCES AT A SHOWER AND HENCE NON
VFR WEATHER IMPACTING A TAF SITE OTHER THAN ERIE...HAVE JUST
MENTIONED VCSH. AT ERI TRIED TO PUT IN A TEMPO FOR THE HIGHER
PRECIP CHANCES THERE. DURING THE MORNING WINDS WILL GENERALLY BE
LIGHT WSW. A MORE DEFINITIVE SHIFT CAN BE EXPECTED WITH THE
TROUGHS PASSAGE THIS AFTERNOON. BY LATE IN THE DAY WE WILL HAVE
NORTH WINDS.
.OUTLOOK...VFR.
&&
.MARINE...
HAVE CONTINUED THE SMALL CRAFT ADVISORY INTO THE MORNING HOURS FOR
MOST OF THE LAKE. UP THROUGH THE EARLY MORNING HOURS WINDS AT SBI01
AND 45005 ALONG WITH SOME OF THE LAKESHORE OBS WERE A SOLID 15 TO 20
KNOTS WITH THE BUOY REGISTERING 3 FOOTERS. AFTER A CHOPPY START
WINDS/WAVES ARE EXPECTED TO DIMINISH TODAY. THE DIRECTION MAY WAVER
SOME FROM NW TO MORE WESTERLY AND BACK AGAIN TO NNW BY THIS
AFTERNOON. THIS IS FROM A COUPLE OF TROUGHS TO CROSS THE LAKE TODAY.
CONTEMPLATED ADDING THE MENTION OF A CHANCE OF WATERSPOUTS FOR THIS
MORNING...BUT WITH RECENT WIND OBSERVATIONS IT APPEARS THAT THE
CONVERGENT ZONE WITH THIS TROUGH HAS PUSHED INLAND. HIGH PRESSURE
BUILDS ACROSS THE REGION FOR MONDAY THROUGH THURSDAY. IT BEGINS TO
SHIFT EAST OF THE LAKE WEDNESDAY...SO WILL GET SOUTHWEST FLOW BY
THURSDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR
LEZ144>148.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...TK
LONG TERM...OUDEMAN
AVIATION...OUDEMAN
MARINE...OUDEMAN
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
646 AM EDT SUN SEP 9 2012
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL SWING THROUGH THE AREA TODAY. AT
THE SURFACE A TROUGH OF LOW PRESSURE WILL LINGER IN THE AREA.
MONDAY THROUGH WEDNESDAY...HIGH PRESSURE WILL DOMINATE ACROSS THE
REGION.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE...UPPER VORTEX MOVING ACROSS NORTHERN INDIANA HOWEVER MUCH
OF THE RAIN ASSOCIATED WITH THIS HAS DIMINISHED OVER THE PAST
COUPLE HOURS. HRRR ACTUALLY DOES NOT REDEVELOP THE PRECIP FAVORING
INSTEAD MORE SHOWERS ALONG THE NORTHEAST LAKESHORE ESPECIALLY
THROUGH THE MORNING...AND SPOTTY SHOWERS THIS AFTERNOON. WILL DROP
THE LIKELY POP WEST THIS MORNING AND LOWER TO 30-40%.
ELSEWHERE...ALONG THE EAST LAKESHORE...RAIN HAS DIMINISHED QUITE A
BIT. STILL THINK THERE IS MORE TO COME BUT WILL DROP CAT POPS BACK
TO LIKELY. WILL ALSO RESTRICT THE MENTION OF THUNDER TO THE EAST
LAKESHORE WITH THE INSTABILITY OFF THE LAKE. NO OTHER CHANGES.
ORIGINAL...WE ARE MOVING INTO THE SEASON FOR LAKE EFFECT RAINS
AS INCREASINGLY FREQUENT SHOTS OF COLD AIR MOVE ACROSS THE WARM
LAKE ERIE WATERS. MODELS SHOW A SHARP UPPER TROF SWINGING THROUGH
THE GREAT LAKES DURING THE DAY WHILE THE WATER VAPOR LOOP SHOWS A
VIGOROUS UPPER VORTEX DROPPING INTO THE BASE OF THE TROF ACROSS
SRN LWR MI. 850MB TEMPS ARE FORECAST TO BE 6 TO 7C CURRENTLY WHICH
YIELDS CAPES OF 1000-1300J/KG WITH RESPECT TO THE LAKE. RADAR
SHOWING SHOWERS AND THUNDERSTORMS DEVELOPING JUST OFF SHORE AND
MOVING ACROSS LAKE COUNTY AND THEN NORTHEAST ACROSS ASHTABULA AND
ERIE COUNTIES. DRIVING FLOW FOR LAKE EFFECT WILL BE CHANGEABLE
TODAY WITH THE SYSTEM MOVING THROUGH HOWEVER WILL CONTINUE WITH
CATEGORICAL POPS EAST OF CLEVELAND FOR THE MORNING AND THEN DROP
BACK TO CHANCE POPS BY EVENING. ELSEWHERE...UPPER LEVEL VORTEX TO
OUR WEST HAS SHOWERS AND THUNDERSTORMS ASSOCIATED WITH IT...NOW
MOVING INTO NERN INDIANA AND SOUTH CENTRAL MI. EXPECT THIS TO
MAINTAIN ITSELF AND MOVE ACROSS THE REGION FROM WEST TO EAST
THROUGH THE MORNING. CURRENTLY HAVE HIGH CHANCE IN THE GRIDS AND
MAY BUMP THAT TO LIKELY AT LEAST FOR THE MORNING.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
WILL NEED TO HANG ONTO LOW CHANCE/SLIGHT CHANCE POPS NORTHEAST
TONIGHT AND MONDAY GIVEN 850MB TEMPS REMAINING 6 TO 8C THROUGH THE
PERIOD. NEGATIVE INFLUENCES WOULD BE DRIER AIR MOVING IN AS WELL
AS BUILDING HIGH PRESSURE. AFTER THAT HOWEVER THE BALANCE OF THE
SHORT TERM WILL HAVE HIGH PRESSURE ACROSS THE REGION WITH SLOWLY
MODERATING TEMPS INTO MID WEEK AS THE HIGH DRIFTS TO OUR EAST.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
LITTLE CHANGE TO THE FORECAST FOR THE END OF THE WEEK. HIGH PRESSURE
THURSDAY AND TEMPS SEASONABLE. THERE ARE STILL HINTS THAT THE
WEEKEND FRONT WILL BE A LITTLE SLOW. HAVE CONTINUED THE PRECIP
CHANCES FROM FRIDAY NIGHT INTO SATURDAY. WITH THE BETTER CHANCES
THAT THE FRONT WILL HAVE PASSED OR BE OVERHEAD SATURDAY...HAVE
SLIGHTLY COOLER TEMPS...LOWER 70S WITH SOME LINGERING SHOWERS.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
VERY LITTLE IN THE WAY OF ANY CHANGES TO THE TAFS THIS GO AROUND.
A SERIES OF TROUGHS WILL CROSS THE LOCAL AREA OVER THE NEXT 15
HOURS. CURRENT TROUGH IS PRODUCING MODERATE SHRA BETWEEN CLE AND
ERI. EXPECT A LULL AS WE GET A BRIEF PERIOD OF RIDGING AHEAD OF
THE NEXT TROUGH. THIS NEXT TROUGH WILL ARRIVE DURING THE DAYLIGHT
HOURS AND FOR LOCATIONS ALONG AND EAST A CLE/MFD LINE...WITH HAVE
THE EXTRA BOOST OF THE HEATING OF THE DAY. HAVE MAINTAINED THE
VCSH MENTIONS AND THE TEMPOS EAST FOR THE SOMEWHAT BETTER CHANCES
THERE. THUNDER IS A POSSIBILITY. OUTSIDE OF THE SHOWERS...VFR
WEATHER EXPECTED. MVFR WITH PERIODS OF IFR WITHIN THE HEAVIER
SHOWERS. DURING THE MORNING WINDS WILL GENERALLY BE LIGHT
WSW..WITH SOME BACKING AHEAD OF THE NEXT TROUGH. A MORE DEFINITIVE
SHIFT CAN BE EXPECTED WITH THIS AFTERNOONS TROUGH AND BY LATE IN
THE DAY WE WILL HAVE NORTH WINDS.
.OUTLOOK...VFR.
&&
.MARINE...
HAVE CONTINUED THE SMALL CRAFT ADVISORY INTO THE MORNING HOURS FOR
MOST OF THE LAKE. UP THROUGH THE EARLY MORNING HOURS WINDS AT SBI01
AND 45005 ALONG WITH SOME OF THE LAKESHORE OBS WERE A SOLID 15 TO 20
KNOTS WITH THE BUOY REGISTERING 3 FOOTERS. AFTER A CHOPPY START
WINDS/WAVES ARE EXPECTED TO DIMINISH TODAY. THE DIRECTION MAY WAVER
SOME FROM NW TO MORE WESTERLY AND BACK AGAIN TO NNW BY THIS
AFTERNOON. THIS IS FROM A COUPLE OF TROUGHS TO CROSS THE LAKE TODAY.
CONTEMPLATED ADDING THE MENTION OF A CHANCE OF WATERSPOUTS FOR THIS
MORNING...BUT WITH RECENT WIND OBSERVATIONS IT APPEARS THAT THE
CONVERGENT ZONE WITH THIS TROUGH HAS PUSHED INLAND. HIGH PRESSURE
BUILDS ACROSS THE REGION FOR MONDAY THROUGH THURSDAY. IT BEGINS TO
SHIFT EAST OF THE LAKE WEDNESDAY...SO WILL GET SOUTHWEST FLOW BY
THURSDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR
LEZ144>148.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...TK
LONG TERM...OUDEMAN
AVIATION...OUDEMAN
MARINE...OUDEMAN
AREA FORECAST DISCUSSION
NWS PORTLAND OR
200 PM PDT SUN SEP 9 2012
.SYNOPSIS...A COLD FRONT FROM THE GULF OF ALASKA WILL PUSH THROUGH
THE REGION LATE TONIGHT AND EARLY MON BRINGING A SHOT OF RAIN TO
MANY AREAS ALONG WITH COOLER AIR. HIGH PRESSURE WILL SLOWLY BUILD
INTO THE REGION TUESDAY AND WEDNESDAY...RESULTING IN RISING
TEMPERATURES AND PLENTY OF SUNSHINE.
&&
.SHORT TERM...CAMERAS AND A FEW OBSERVATIONS SHOW SOME LIGHT RAIN
STILL OCCURRING ALONG THE COAST EARLY THIS AFTERNOON...WITH MARINE
CLOUDS STILL HANGING IN OVER MUCH OF THE FORECAST AREA. WELL
ADVERTISED COLD FRONT IS SEEN ON SATELLITE PICTURES STRETCHING FROM
NEAR THE N END OF VANCOUVER ISLAND SW PAST ABOUT 45N 135W. SATELLITE
DERIVED PRECIPITABLE WATER VALUES ON THE ORDER OF 1.25 INCHES
PRECEDE THE FRONT. WITH RELATIVELY DEEP MOISTURE AND A SHARP
FRONT...EXPECT A PERIOD OF SEVERAL HOURS OF RAIN LIKELY FOR MUCH OF
THE NORTHERN HALF OF THE FORECAST AREA...WITH LOWER POPS TO THE S.
RECENT MODEL RUNS CONTINUE TO SHOW THE MOST LIKELY TIME FOR RAINFALL
TO OCCUR AFTER MIDNIGHT TONIGHT IN THE NW PART OF THE AREA...AND MON
MORNING FURTHER SE. SATLLITE PICTURES SHOW SOME SHOWERS IN THE
COLDER AIR BEHIND THE FRONT...BUT MOST OF THE INSTABILITY IS
EXPECTED TO PASS BY TO THE N. STILL...WILL LEAVE IN SOME LOW POPS
FOR SHOWERS BEHIND THE FRONT LATER IN THE DAY MON.
DRYING OF THE AIR MASS KICKS IN RELATIVELY QUICKLY MON NIGHT AND TUE
AS LOW LEVEL FLOW TURNS MORE NORTHERLY AND UPPER TROUGH PASSES BY TO
THE E. COOL AIR EXPECTED TO LINGER INTO TUE BEFORE WARMING BACK
ABOVE SEASONAL NORMALS WED IN RESPONSE TO THE BUILDING UPPER RIDGE.
.LONG TERM...A STRONG UPPER LEVEL RIDGE WILL BE IN PLACE OVER THE
FORECAST AREA BY EARLY WEDNESDAY...WITH THE AXIS MOVING THROUGH THE
AREA BY EARLY THURSDAY. WITH AN EQUALLY STRONG THERMAL TROUGH
PATTERN DEVELOPING AT THE SURFACE...TEMPERATURES SHOULD BE ALLOWED
TO WARM WELL ABOVE NORMAL EACH DAY OF THE LAST HALF OF THE WEEK
UNDER CLEAR SKIES AND OFFSHORE FLOW. DISCOUNTING THE MOST CURRENT
RUN OF THE ECMWF...WHICH IS QUITE DIFFERENT FROM PREVIOUS RUNS...THE
DRY PATTERN SHOULD CONTINUE INTO NEXT WEEKEND AS THE UPPER LEVEL
RIDGE BEGINS TO WEAKEN AND MOVE EASTWARD. BROWN
&&
.AVIATION...CIGS HAVE LINGERED IN THE LOW VFR CATEGORY TODAY...WITH
MOST LOCATIONS HOVERING IN THE 3500-5000 FT RANGE...THOUGH THERE ARE
POCKETS OF MVFR RETURNING THIS AFTERNOON. EXPECT THIS TO CONTINUE
THROUGH THE EVENING UNTIL THE MAIN FRONTAL FORCING COMES IN. FRONTAL
RAIN IS NOT EXPECTED AT THE S WA/N OR COAST UNTIL ABOUT 5Z OR SO.
THE COAST WILL CONTINUE TO REMAIN IN MVFR CONDITIONS WITH OFF AND ON
LIGHT RAIN/DRIZZLE IN A WEAK ISENTROPIC LIFT REGIME. EXPECT A PERIOD
OF MVFR INLAND LATE TONIGHT INTO EARLY MONDAY WITH THE BEST FRONTAL
FORCING OCCURRING BETWEEN 10-15Z. HIGHEST CONFIDENCE IN THE NORTH
VALLEY.
THE FRONTAL PASSAGE AT ASTORIA SHOULD BE AROUND 9Z OR SO...AROUND
15Z IN THE NORTH INTERIOR...AND SLIGHTLY LATER FURTHER SOUTH DOWN
THE VALLEY. WINDS SHIFT FOLLOWING THE FRONT TO WNW NEAR KPDX...MORE
NNW AS YOU GET FURTHER SOUTH. CONDITIONS RETURN TO VFR WITH
OCCASIONAL MVFR MAINLY FOR COASTAL AREAS BEHIND THE FRONT. KMD
KPDX AND APPROACHES...OVC SKIES WITH CIGS FROM 3500-5000 FT WILL
CONTINUE THROUGH THE EVENING. 70 PERCENT OF MVFR CIGS JUST AHEAD OF
THE COLD FRONT. BEST CHANCE FOR CIGS AND PRECIP WILL BE FROM 10-15Z.
KMD
&&
.MARINE...MODERATE SOUTHERLY WINDS CONTINUE ACROSS THE COASTAL
WATERS AHEAD OF A SHARP SURFACE TROUGH APPROACHING THE COAST. WE
HAVE EVEN SEEN A STEADY PERIOD OF WINDS/GUSTS 22-29 KT TO OUR INNER
NORTHERN WATERS TODAY FROM 15-21Z AS REPORTED BY THE CAPE D AND
CLATSOP SPIT MESONET SITES. FURTHER OFFSHORE BUOY 29 WINDS HAVE FOR
THE MOST PART BEEN 20 KT OR LESS THOUGH THERE HAVE BEEN A FEW GUSTS
INTO THE 20S. GRADIENT LOOKS TO SLACKEN ENOUGH LATER THIS AFTERNOON
OR EARLY EVENING TO BRING WINDS BACK TO AROUND 20 KT FOR THE INNER
WATERS.
BEHIND THE SURFACE TROUGH...A COLD FRONT CURRENTLY IN THE VICINITY
OF WILL BRING A SHARP WIND SHIFT TO NW WINDS MON MORNING. SOME LOW
END SCA GUSTS ARE POSSIBLE IN THE NORTHERN OUTER WATERS AROUND TO
SLIGHTLY AFTER MIDNIGHT INTO EARLY MONDAY AS THERE WILL BE SOME
FAIRLY STRONG COLD ADVECTION...WHICH OFTEN CAUSES WINDS TO
OVER-PERFORM WHAT MODELS SUGGEST. COULD GO EITHER WAY ON THIS
ONE...HI RES HRRR SUPPORTS THE GFS WITH GUSTS AGAIN IN THE MID
20S...SO WILL GO WITH A RELATIVELY SHORT LIVED ADVISORY FOR POINTS
WELL OFFSHORE. NORTHERLY FLOW THEN INCREASES THROUGHOUT THE WATERS
TUE-THU AS STRONG HIGH PRESSURE BUILDS OVER THE NE PACIFIC AND A
THERMAL TROUGH BUILDS UP THE COAST FROM NORTHERN CALIFORNIA. SEAS
WILL LIKELY BECOME QUITE STEEP DURING THIS PERIOD...AND MAY APPROACH
10 FT. KMD
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FOR WATERS FROM CAPE SHOALWATER
WA TO CASCADE HEAD OR OUT 10 NM UNTIL 5 PM PDT.
SMALL CRAFT ADVISORY FOR WINDS FOR WATERS FROM CAPE SHOALWATER
WA TO CASCADE HEAD OR FROM 10 TO 60 NM FROM 9 PM TO 5 AM PDT.
&&
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
600 PM CDT SUN SEP 9 2012
.SHORT TERM...TONIGHT THROUGH WEDNESDAY
340 PM CDT SUN SEP 9 2012
AT 3 PM...A 1021 MB SURFACE HIGH WAS CENTERED OVER SOUTH-CENTRAL
MINNESOTA AND NORTH-CENTRAL IOWA. MEANWHILE ALOFT...A SHORT WAVE
TROUGH MOVING SOUTHEAST ACROSS WISCONSIN. THE COMBINATION OF COLD
AIR ALOFT AND 850 TO 750 MB MOISTURE HAS RESULTED IN A SCATTERED
TO BROKEN DECK OF OPEN CELLULAR CLOUDS ACROSS SOUTHERN AND EASTERN
WISCONSIN.
WITH THE LOSS OF DIURNAL HEATING LATE THIS AFTERNOON AND EARLY
EVENING AND SUBSIDENCE IN THE WAKE OF THIS WAVE...THESE CLOUDS
WILL QUICKLY DISSIPATE. THE SURFACE HIGH WILL DRIFT SOUTHEAST
ACROSS EASTERN IOWA AND CENTRAL ILLINOIS TONIGHT. THE BUFKIT
SOUNDINGS CONTINUE TO SHOW THAT THERE WILL BE A DEEP LAYER /UP TO
800 MB/ OF LIGHT WINDS /5 KNOTS OR LESS/ THROUGH 09.06Z...AND THEN
THE WINDS JUST ABOVE THE SURFACE WILL QUICKLY CLIMB INTO THE 10 TO
15 KNOT RANGE AS THE HIGH PULLS AWAY FROM THE AREA. THIS WILL
GREATLY LIMIT THE DEPTH OF THE BOUNDARY LAYER. IN ADDITION...THE
DRY DEW POINTS /IN THE MID AND UPPER 40S/ WILL SLOW THE SATURATION
OF THE BOUNDARY LAYER. DUE TO THE WINDS LATE TONIGHT AND DRY DEW
POINTS...CHANGED THE FORECAST TO SAY PATCHY FOG INSTEAD OF AREAS
OF FOG IN MOST LOCATIONS. THE ONE EXCEPTION MAY BE IN THE
WISCONSIN RIVER VALLEY WHERE ITS DEPTH AND STEEPNESS MAY AID IN A
DEEPER BOUNDARY LAYER.
ON MONDAY AND TUESDAY...THERE WILL BE A STRENGTHENING SURFACE
PRESSURE GRADIENT AS THE HIGH MOVES EAST OF THE AREA AND A COLD
FRONT MOVES SLOWLY EAST ACROSS THE DAKOTAS...AND WESTERN AND
NORTHERN MINNESOTA. THE SOUTH WINDS WILL RANGE FROM 15 TO 25 MPH
ON BOTH AFTERNOONS. 850 MB TEMPERATURES WILL BE ABOUT 9C WARMER
/AROUND 16C/ ON MONDAY AFTERNOON AND ANOTHER 4C RISE /AROUND 20C/
ON TUESDAY AFTERNOON. THESE TEMPERATURES ARE AROUND 2 STANDARD
DEVIATIONS ABOVE NORMAL FOR TUESDAY. THIS WILL RESULT IN HIGH
TEMPERATURES AROUND 90 DEGREES MAINLY NORTHWEST OF A CHARLES CITY
IOWA TO BLACK RIVER FALLS LINE. RECORD HIGH TEMPERATURES FOR THIS
DATE ARE IN THE MID 90S.
ON WEDNESDAY...THE MODELS CONTINUE TO SLOW THE EASTWARD PROGRESS
OF THE SURFACE COLD FRONT. WITH VERY AIR LOCATED ALOFT AHEAD OF
THIS FRONT...THE PRECIPITATION IS MAINLY ANABATIC. DUE TO THIS...
THE PRECIPITATION WAS LOWERED ACROSS NORTHERN WISCONSIN AND
SOUTHEAST MINNESOTA...AND REMOVED FOR THE REMAINDER OF THE AREA.
IN ADDITION...HIGH TEMPERATURES WERE RAISED SOME IN THE
ANTICIPATION OF MORE SUNSHINE AND LESS CLOUD COVER.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
340 PM CDT SUN SEP 9 2012
FROM WEDNESDAY NIGHT THROUGH FRIDAY...MANY OF 09.12Z MODELS SHOW
THAT A COLD FRONT WILL MOVE SLOWLY SOUTHEAST THROUGH THE MID AND
UPPER MISSISSIPPI RIVER VALLEY AND GREAT LAKES. THE COMBINATION OF
MODERATE TO STRONG FRONTOGENESIS AND THE RIGHT ENTRANCE REGION OF
THE UPPER LEVEL JET WILL ENHANCE THE LIFT IN THE WAKE OF THE FRONT.
IN ADDITION BOTH THE GEM AND ECMWF DEVELOP A LOW PRESSURE SYSTEM
OVER THE REGION ON FRIDAY. IF THIS OCCURS...THE PRECIPITATION
COULD LINGER INTO FRIDAY NIGHT. CONSALL TEMPERATURE AND PRECIPITATION
GRIDS LOOKED MUCH BETTER THAN THE ALL BLEND FOR WEDNESDAY NIGHT
AND THURSDAY...SO WENT WITH THEM INSTEAD. WITH THIS SAID...MAY NOT
BE HIGH ENOUGH YET WITH THE PRECIPITATION CHANCES AND COLD ENOUGH
WITH THE DAYTIME TEMPERATURES. IF THE GEM AND ECMWF ARE CORRECT
MAY HAVE TO ALSO RAISE THE PRECIPITATION CHANCES FOR THURSDAY
NIGHT INTO FRIDAY NIGHT.
&&
.AVIATION...
600 PM CDT SUN SEP 9 2012
RIVER VALLEY FOG AT KLSE IS THE MAIN AVIATION CONCERN WITH HIGH
PRESSURE OVERHEAD RESULTING IN A FAVORABLE SCENARIO. WINDS WILL
DECOUPLE QUICKLY WITH SUNDOWN...WITH LIGHT SFC WINDS THROUGH THE
NIGHT. MODELS CONTINUE TO POINT TO AN INCREASE IN WINDS ABOVE THE
INVERSION BY 09Z...A CONSISTENT SIGNAL OVER THE PAST COUPLE DAYS.
NOT CONVINCED THIS IS SUPPORTED BY THE SYNOPTIC SETUP. EVEN IF THESE
STRONGER WINDS ARE REALIZED...THE INVERSION SHOULD BE WELL IN PLACE
WHERE THERE WOULD BE LITTLE IMPACT ON THE FG POTENTIAL. MEANWHILE
TDS DID NOT DROP OFF AS MUCH AS PREVIOUSLY THOUGHT. BUFKIT RAP IS
WOEFULLY TOO HIGH WHILE THE NAM12 IS TOO DRY. THE NAM12 STAYS DRY
ALL NIGHT...WITH NO EVENING REBOUND. BELIEVE THIS IS IN CORRECT.
WILL OPT TO STAY WITH BCFG AT KLSE FOR THE MOMENT...BUT WILL
CONTINUE TO MONITOR OBS CLOSELY. IF THE TD CLIMBS 5-7 DEGREES THIS
EVENING...THE 1/4SM FG RISK CLIMBS ALSO.
THE HIGH SHIFTS EAST ON MONDAY...WITH A TIGHT PRESSURE GRADIENT
RESULTING IN A BREEZY SOUTHERLY FLOW. SOME AFTERNOON MIXING SHOULD
RESULT IN GUSTS UP TO 30 MPH AT KRST.
&&
.CLIMATE...TUESDAY
340 PM CDT SUN SEP 9 2012
HIGH TEMPERATURES WILL CLIMB TO AROUND 90 DEGREES MAINLY NORTHWEST
OF A CHARLES CITY IOWA TO BLACK RIVER FALLS LINE ON TUESDAY. THE
RECORD HIGHS FOR THIS DATE ARE...
LA CROSSE WI - 97 IN 1897
MEDFORD WI - 95 IN 1900
ROCHESTER MN - 94 IN 1931
AUSTIN MN - 92 IN 1948
CHARLES CITY IA - 96 IN 2000
DECORAH IA - 97 IN 1895
&&
.FIRE WEATHER...MONDAY AND TUESDAY
340 PM CDT SUN SEP 9 2012
WITH THE STRONG WARMING AND INCREASING GRADIENT WINDS MON/TUE...
POTENTIAL EXISTS FOR SOME CRITICAL FIRE WEATHER CONDITIONS BOTH
MONDAY AND TUESDAY AFTERNOONS. HOW CRITICAL WILL DEPEND ON DIURNAL
MIXING AND IF DEW POINTS DROP. FOR NOW MINIMUM AFTERNOON
HUMIDITIES BOTH DAYS LOOK TO RANGE FROM THE MID 20S TO AROUND 30.
HOWEVER THESE HUMIDITIES WILL BE COMBINED WITH THE DRYING
LANDSCAPE/MATURING VEGETATION...AND SOUTH TO SOUTHWEST WINDS IN
THE 15-25 MPH GUSTS OF AROUND 30 MPH. ESPECIALLY CONCERNED ABOUT
THE LONG GRASSES AND POTENTIAL FOR FIELD FIRES AS SOME FARMERS MAY
TRY TO HARVEST SOME FIELDS. FIRE WEATHER USER GROUPS WERE NOT THAT
CONCERNED SO HELD OFF ISSUING A FIRE WEATHER WATCH.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
340 PM CDT SUN SEP 9 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM.....BOYNE
LONG TERM......BOYNE
AVIATION.......RIECK
CLIMATE........BOYNE
FIRE WEATHER...BOYNE
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
253 PM CDT SUN SEP 9 2012
.SHORT TERM...TONIGHT AND MONDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A LARGE HIGH
PRESSURE SYSTEM STRETCHING ACROSS THE GREAT PLAINS...AND MOVING EAST
INTO THE WESTERN GREAT LAKES. MORNING LOW STRATUS BURNED OFF INTO A
CU FIELD WITH HELP FROM MOISTURE FLUXES ADVECTING OFF LAKE
SUPERIOR. A FEW SHOWERS EVEN POPPED UP OVER THE U.P...BUT DIDNT
HAVE ENOUGH TO MAKE IT INTO IRON MOUNTAIN OR WASHINGTON ISLAND EARLY
THIS AFTERNOON. AS A STRONG CANADIAN SURFACE MOVES ACROSS THE
AREA...TEMPS AND CLOUD COVER ARE THE MAIN FORECAST CONCERNS.
TONIGHT...HIGH PRESSURE WILL BE OVER THE STATE DURING THE EVENING
THEN DRIFT TOWARDS THE CENTRAL GREAT LAKES OVERNIGHT. WITH RIDGING
THROUGH THE COLUMN...MAY SEE SCT COVERAGE OF LINGERING CU OVER DOOR
COUNTY DURING EARLY EVENING...BUT SUBSIDENCE SHOULD WIN OUT FAIRLY
QUICKLY WHICH WILL LEAVE CLEAR CONDITIONS THEREAFTER. PWATS WILL
FALL BELOW 0.5 INCHES OVERNIGHT AND WINDS WILL BE CALM...AND THAT
WILL LEAD TO GOOD RADIATIONAL COOLING CONDITIONS. BIAS CORRECTED
GUIDANCE DROPS LOWS INTO THE MID TO UPPER 30S OVER LINCOLN AND
NORTHERN VILAS COUNTY...AND WILL MENTION PATCHY FROST IN THE
FORECAST. LOWS IN THE 40S OUTSIDE OF THE COLD SPOTS.
MONDAY...HIGH PRESSURE WILL BE MOVING TO THE EASTERN GREAT LAKES ON
MONDAY AND WILL START OUT THE DAY WEST OF THE 850MB RIDGE AXIS. AS
A RESULT...WINDS WILL SHIFT TO THE SOUTHWEST AND WILL SEE A WARMING
TREND COMMENCE. THE AIRMASS ADVECTING INTO THE REGION FROM THE
GREAT PLAINS IS VERY DRY...SO EXPECT A SEASONABLE AND MOSTLY SUNNY
DAY WITH HIGHS IN THE LOW TO MID 70S.
.LONG TERM...MONDAY NIGHT THROUGH NEXT SUNDAY...PRECIPITATION TRENDS
FOR THE MID TO LATE PART OF THE UPCOMING WEEK...AND TEMPERATURES...
ARE THE MAIN FCST CONCERNS.
STRONG RETURN FLOW WILL BE ONGOING AT THE BEGINNING OF THE PERIOD...
AHEAD OF AN APPROACHING COLD FRONT. MIN TEMPS WILL BE MILDER ON
MONDAY NIGHT...MAINLY IN THE 50S. MIXING THROUGH 900-875 MB ON
TUESDAY SHOULD YIELD MAX TEMPS IN THE 80-85 RANGE...WARMEST IN THE
SANDY SOIL REGION OF CENTRAL WI. BREEZY CONDITIONS ARE EXPECTED...
WITH SW WINDS GUSTING OVER 25 MPH. THE COMBINATION OF WARM TEMPS...
GUSTY WINDS AND FAIRLY LOW RELATIVE HUMIDITY (30-35 PERCENT) WILL
RESULT IN ELEVATED FIRE DANGER...BUT CONDITIONS DO NOT WARRANT
ANY HEADLINE CONSIDERATIONS.
THE PREVIOUSLY-MENTIONED COLD FRONT IS EXPECTED TO MOVE INTO FAR
NC WI LATE TUESDAY NIGHT. WITH AN INITIAL LACK OF MOISTURE AND
THE UPPER LEVEL FORCING LAGGING TO THE WEST...WILL KEEP THE DRY
FCST INTACT. MUCH ABOVE NORMAL TEMPERATURES ARE ANTICIPATED...
WITH READINGS IN THE 60-65 RANGE.
THE COLD FRONT IS EXPECTED TO SHIFT TOWARD THE FOX VALLEY/LKSHR
AREAS ON WEDS...WITH POST-FRONTAL SHOWERS DEVELOPING NW OF AN
MFI-IMT LINE. SUNSHINE AND COMPRESSIONAL HEATING AHEAD OF THE
FRONT SHOULD STILL ALLOW TEMPS TO REACH THE LOWER TO MIDDLE 80S
OVER PARTS OF C/NE/EC WI...SO HAVE RAISED MAX TEMPS SEVERAL
DEGREES.
HAVE INCREASED POPS FOR THE WEDS NGT/THU PERIOD...AS POST-
FRONTAL PCPN INCREASES DUE TO AN APPROACHING UPPER TROF...UPPER
DIVG IN THE RRQ OF A STRONG JET STREAK...AND MID-LEVEL
FRONTOGENETIC FORCING. PCPN CHANCES BECOME LESS CLEAR DURING
THE THU NGT-FRI NGT PERIOD...AS THE GFS/GEFS SHOVE THE FRONTAL
SYSTEM AND ASSOC PCPN BAND TO OUR EAST...WHILE THE ECMWF STALLS
THE FRONT AND LIFTS A SFC WAVE NORTHWARD ALONG THE BOUNDARY...
RESULTING IN A RENEWED SWATH OF RAIN ACROSS THE AREA LATE
THURSDAY NIGHT INTO FRIDAY NIGHT. DUE TO THE UNCERTAINTY...
HAVE KEPT THE TYPICAL MODEL BLEND FOR NOW...WHICH SIDES TOWARD
THE DRIER SIDE OF THE SOLUTIONS.
ANOTHER WEAK COLD FRONT IS EXPECTED OVER THE WEEKEND...BUT IS
NOT EXPECTED TO BE A BIG WEATHER MAKER.
AFTER WEDNESDAY...THE INCOMING CANADIAN AIR MASS WILL BRING
TEMPERATURES BACK CLOSER TO NORMAL FOR THE MIDDLE OF SEPTEMBER.
&&
.AVIATION...SCATTERED AFTERNOON CLOUDS MAY BE BROKEN FOR A PERIOD OF
TIME EARLY TO MID AFTERNOON BEFORE CLOUDS GRADUALLY DISSIPATE BY
EARLY THIS EVENING. CLEAR SKIES THEREAFTER...THOUGH LIGHT WINDS
WILL ALLOW PATCHY GROUND FOG TO FORM LATE TONIGHT. VFR CONDITIONS
TOMORROW ONCE THE GROUND FOG BURNS OFF.
MPC
&&
.MARINE...PERSISTENT AND STRENGTHENING SOUTH TO SOUTHWEST FLOW
WILL LEAD TO HAZARDOUS CONDITIONS FOR SMALL CRAFT FROM MONDAY
NIGHT THROUGH WEDNESDAY. WILL BE ISSUING SMALL CRAFT ADVISORIES
WITH THIS FCST PACKAGE.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/TSK
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1145 AM CDT SUN SEP 9 2012
.UPDATE...NORTHWEST TO NORTH LOW-LEVEL FLOW WILL KEEP LAKE-EFFECT
RAIN SHOWERS OUT OVER LAKE MICHIGAN THIS AFTERNOON. OTHERWISE
DAYTIME HEATING AND EVAPORATION OF GROUND MOISTURE LEFT OVER FROM
SATURDAY/S RAIN WILL ALLOW FOR SCATTERED CLOUDS THIS AFTERNOON.
.AVIATION/18Z TAFS/...VFR CONDS SUNDAY AFTERNOON AND TONIGHT.
SCATTERED AFTERNOON CUMULUS CLOUDS WITH BASES OF 1000 TO 2500 FEET
RISING TO 4000 TO 5000 FT AS MIXING DEPTH INCREASES WITH HEATING.
NORTHWEST TO NORTH SURFACE WINDS AT 5 TO 10 KNOTS WILL BECOME LIGHT
AND VARIABLE TONIGHT AS SURFACE HIGH PRESSURE RIDGE MOVES ACROSS.
FOG A POSSIBILITY TONIGHT IN RIVER VALLEYS AND LOW SPOTS. WISCONSIN
RIVER VALLEY WILL PROBABLY DROP TO USUAL IFR CONDS WHICH IS NORMAL
FOR THIS TIME OF YEAR WITH HIGH PRESSURE OVERHEAD AND LEFTOVER
MOISTURE IN BOUNDARY LAYER. ON MONDAY...HIGH PRESSURE MOVES EAST AND
SOUTH TO SOUTHWEST LOW LEVEL FLOW DEVELOPS...ON ORDER OF 8 TO 13
KNOTS AT SURFACE WITH 20-25 KNOTS AT 5000 FT AGL IN AFTERNOON.
REMAINDER OF PREVIOUSLY ISSUED DISCUSSION FOLLOWS...
.TODAY AND TONIGHT...FORECAST CONFIDENCE MEDIUM TO HIGH.
SCATTERED SHOWERS DEVELOPING IN REGION OF LAND BREEZE CONVERGENCE
OVER MID-LAKE IN WAKE OF DEPARTING SHORT WAVE. FORECAST SOUNDINGS
SHOW FAVORABLE DELTA T AND NORTH-NORTHEAST FLOW DEVELOPING BELOW 5K
FT...WITH NAM...GFS AND RUC 1000-900MB LAYER WIND/CONVERGENCE
FORECASTS INDICATING POTENTIAL OF SHOWERS BRUSHING THE SHORE BETWEEN
12Z AND 18Z. WILL KEEP SOME POPS ALONG THE SHORE FROM MILWAUKEE
SOUTH.
OTHERWISE DRY TROUGH THE PERIOD WITH UPPER RIDGING AND SURFACE HIGH
PRESSURE BUILDING OVER THE REGION...WITH COOL TEMPERATURES. 925MB
TEMPERATURES SUPPORT DAYTIME HIGHS IN THE LOW TO MID 70S WEST TO
AROUND 70 EAST. GOOD RADIATIONAL CONDITIONS TONIGHT WILL ALLOW LOWS
TO FALL INTO THE MID 40S AWAY FROM THE LAKE.
MONDAY THROUGH WEDNESDAY - CONFIDENCE...MEDIUM
BROAD 500 MILLIBAR ANTICYCLONIC FLOW ACROSS THE CWA THIS PERIOD.
SURFACE/850 HIGHS TO THE EAST. A WARMER SOUTHERLY REGIME KICKS IN.
500 MILLIBAR FLOW BECOMES MORE SOUTHWEST ON WEDNESDAY THOUGH BEST
FORCING...BOTH ALOFT AND IN THE LOW LEVELS...REMAINS TO THE NORTH
AND NORTHWEST OF THE CWA. 925 TEMPS SLOW TO RESPOND MONDAY...BUT A
SLIGHT WARMING NOTED. A MORE PRONOUNCED WARMING ON TUESDAY WITH 925
TEMPS BACK TO THE LOW 20S CELSIUS...WITH POSSIBLE MID 20S WEDNESDAY
WITH SOUTHWEST WINDS MAINTAINING THE WARM AIRMASS AHEAD OF THE
FRONT. SO TEMPS WELL INTO THE
WEDNESDAY NIGHT AND THURSDAY - CONFIDENCE...LOW
SURFACE BOUNDARY AND 850 BAROCLINIC ZONE SAGS INTO SRN WI THIS
PERIOD WITH PRECIP CHANCES INCREASING. 500 MILLIBAR FLOW BECOMES
SOUTHWEST WITH INCREASED POTENTIAL FOR RIPPLES RIDING NORTHEAST IN
THE FLOW. MAIN TROUGH AXIS BACK IN MINNESOTA WITH ECMWF HAVING TWO
CONSECUTIVE RUNS OF SHOWING A MUCH MORE POTENT VORT CENTER.
THURSDAY NIGHT AND FRIDAY - CONFIDENCE...LOW
12Z AND 00Z ECMWF SHOWING A RATHER SIGNIFICANT SHORTWAVE/VORT MAX
CRASHING INTO THE AREA WITH ABUNDANT QPF. SURFACE LOW PRESSURE WOULD
TRACK SOUTH OF THE AREA WITH A SIGGY RAIN EVENT WITH DEF ZONE PRECIP
SHIELD ACROSS MUCH OF WI. THE GFS AND GEM ARE WEAKER WITH THE UPPER
WAVE CROSSING WI AND IMPLY DRYING WORKING IN WITH HIGH PRESSURE.
LOTS TO SORT OUT YET WITH THIS SYSTEM...BUT THE ECMWF HAS SHOWN SOME
CONSISTENCY YET THERE IS SOME CONSENSUS BETWEEN THE GEM AND GFS.
SATURDAY - CONFIDENCE...LOW TO MEDIUM
WHILE THE DETAILS BETWEEN THE MODELS VARY THE CONSENSUS IS FOR GOING
WITH A DRY FORECAST AS SYSTEM SHIFTS AWAY.
&&
.AVIATION/12Z TAFS/...PATCHY MVFR STRATUS AND FOG WILL CLEAR AROUND
OR SHORTLY AFTER ISSUANCE...WITH VFR CONDITIONS THROUGH THE PERIOD.
NORTH WINDS WILL BE GUSTY FOR A TIME AT EASTERN TAF SITES THIS
MORNING...THEN WEAKEN THIS AFTERNOON AS THEY SHIFT NORTHEAST.WILL
HAVE TO WATCH FOR PATCHY FOG AT KENW TONIGHT...WITH DEW POINTS
HOLDING UP A BIT MORE THAN INLAND AREAS...AND LAND BREEZE NOT AS
SIGNIFICANT A FACTOR AS AT KMKE.
&&
.MARINE...WILL NOT ISSUE A SMALL CRAFT ADVISORY AT THIS TIME...EVEN
THOUGH WINDS BECOME FAVORABLE FOR A TIME AS THEY SHIFT FROM OFFSHORE
EARLY TO THE NORTH...AND THEN NORTHEAST THROUGH THE MORNING INTO THE
EARLY AFTERNOON. GRADIENT WEAKENS WITH THE MORE FAVORABLE FETCH
REDUCING WIND SPEEDS WHICH WILL LIMIT WAVE HEIGHTS.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...REM/AFK
MONDAY THROUGH SATURDAY...COLLAR