Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/06/12
AREA FORECAST DISCUSSION...CORRECTED
NWS PHOENIX AZ
300 AM MST TUE SEP 4 2012
.UPDATE...UPDATED AVIATION SECTION...
.SYNOPSIS...
HIGH PRESSURE ALOFT WILL REMAIN CENTERED OVER OR NEAR NEW MEXICO
THROUGH MUCH OF THE UPCOMING WEEK. VERY MOIST AND MODERATELY
UNSTABLE AIR OVER THE AREA WILL LEAD TO STORM CHANCES ACROSS THE
REGION FOR MUCH OF THIS WEEK. LOCALLY HEAVY RAINFALL AND STRONG
WINDS ARE LIKELY WITH THE STRONGER STORMS.
&&
.DISCUSSION...
STORM ACTIVITY FOR THE NIGHT CONTINUES OVER FAR SOUTHEAST ARIZONA
BUT IS NOT WIDESPREAD. MADE UPDATES TO THE FORECAST TO DROP THE POPS
FROM MOST AREAS. A STRAY ECHO OR TWO LIE CLOSE ENOUGH TO SOUTHWEST
MARICOPA/NORTHWEST PINAL/SOUTHERN GILA COUNTIES THAT A SLIGHT CHANCE
WAS LEFT FOR THIS EVENING...GOING TO ZERO FOR THE OVERNIGHT HOURS.
DEEPER MOISTURE IS PROGGED TO SHIFT OVER SOUTHEAST ARIZONA TUESDAY
FOR A BETTER CHANCE OF STORMS OVER THE CENTRAL DESERTS. AS USUAL
THOUGH...FORECAST SOUNDINGS SUGGEST THAT OUTFLOWS WILL BE NECESSARY
TO OVERCOME SOME CONVECTIVE INHIBITION. SIMILAR SITUATION WEDNESDAY.
SOUTHEASTERLY STEERING FLOW WEDNESDAY MAY BE BEST OPPORTUNITY FOR
PHOENIX AREA. MEANWHILE...LOWER LEVELS OVER SOUTHEAST CALIFORNIA
START TO LOSE MOISTURE.
&&
.PREVIOUS DISCUSSION ISSUED 300 PM...
LATEST RAP ANALYZED A DIFFUSE TROUGH EXTENDING FROM SOUTHERN NM TO
HERMOSILLO MEXICO...THOUGH THIS IS DIFFICULT TO IDENTIFY ON WV
IMAGERY. STRONG STORMS HAVE DEVELOPED IN THE DIFLUENT REGION BETWEEN
THIS TROUGH AND AN ANTICYCLONE CENTERED NEAR THE WHITE MOUNTAINS.
FURTHER NORTH ACROSS THE MOGOLLON RIM...OROGRAPHICALLY-INDUCED
SHOWERS AND THUNDERSTORMS HAVE ALSO FORMED BUT CONTINUE TO DRIFT
NORTHEASTWARD TOWARDS THE CO PLATEAU WITHIN A 10 KT MEAN LAYER FLOW.
EARLIER MOISTURE SURGE ALONG THE GOC AND ACROSS YUMA AND THE
IMPERIAL VALLEY YIELDED HEAT INDICES BETWEEN 110 AND 115
DEGREES...BUT HAVE SINCE LOWERED AS THE ATMOSPHERE MIXES OUT.
LATEST MESOANALYSIS SHOWS MODERATELY STRONG CONVECTIVE INHIBITION
ACROSS MUCH OF THE FORECAST AREA...LARGELY DUE TO A RIDGE AND THE
ASSOCIATED WARM/DRY AIR IN THE 800-700 MB LAYER. MODEL SOUNDINGS
INDICATE THAT THIS LAYER WILL MOISTEN ACROSS WESTERN AZ THIS
AFTERNOON...WHICH WILL HELP TO ERODE THE CIN AND INITIATE ISOLATED
CONVECTION. NMM-B BASED WRF FROM UNIV OF AZ APPEARS TO HAVE THE BEST
HANDLE ON THE SHORT-TERM EVOLUTION AND SUGGESTS STORMS WILL FIRE
ACROSS YUMA AND LA PAZ COUNTIES THIS AFTERNOON. ISOLATED ACTIVITY IN
THE IMPERIAL VALLEY ALSO CANNOT BE RULED OUT...GIVEN THE
SOUTHWESTERLY STEERING FLOW AND PRESENCE OF CB/TCU ON VISIBLE
SATELLITE ALONG THE BAJA SPINE. ACROSS THE PHOENIX METRO AREA...THE
MAIN IMPACT APPEARS TO BE THE POTENTIAL BLOWING DUST FROM
THUNDERSTORMS TO THE SOUTH...THOUGH POPS REMAIN 5 TO 10 PERCENT
ABOVE THE CLIMATOLOGICAL AVERAGE.
IN THE SHORT TERM (MONDAY-WEDNESDAY)...EXPECT A DAY TO DAY INCREASE
IN STORM ACTIVITY...ESPECIALLY OVER AZ PORTION OF THE CWA. VERY
MOIST AIR MASS CURRENTLY EXISTS OVER NORTHWEST MEXICO. SYNOPTIC
PATTERN...WITH RATHER STRONG TROUGH OF LOW PRESSURE MOVING EAST
ACROSS SOUTH-CENTRAL CANADA WHILE A TROPICAL DISTURBANCE (NOW TS
JOHN) MOVES WEST JUST OFF THE SOUTHERN END OF BAJA
CALIFORNIA...CERTAINLY SUPPORTS A MOISTURE INCREASE OVER OUR
AREA...AND THE GFS/ECMWF/NAM CERTAINLY AGREE THE ATMOSPHERE WILL
MOISTEN SIGNIFICANTLY DURING THE NEXT 36 HRS.
WITH ATMOSPHERIC MOISTENING CONTINUING ON TUESDAY (ANOMALOUSLY HIGH
PRECIPITABLE WATER NEAR 2" BY THEN) AND MORE DIFLUENT UPPER LEVEL
FLOW OVER SOUTHEAST AZ BY TUESDAY AFTN...PRECIP CHANCE WILL BE A BIT
GREATER TUESDAY EVENING...ESPECIALLY OVER SOUTH-CENTRAL AZ. VERY
MOIST AND MODERATELY UNSTABLE ATMOSPHERE REMAINS IN PLACE ON
WEDNESDAY...AND PRECIP CHANCES WILL BE ENHANCED AS A WEAK WEATHER
DISTURBANCE MOVES WEST ACROSS SONORA. WITH SUCH HIGH ATMOSPHERIC
MOISTURE CONTENT...DECENT CAPE...AND WEAK STEERING FLOW...LOCALLY
HEAVY RAINFALL CAN BE EXPECTED...THOUGH STRONG/DAMAGING WINDS WILL
ALSO BE POSSIBLE.
IN THE EXTENDED PERIOD(THURSDAY-SUNDAY)...NUMERICAL MODELS INDICATE
ATMOSPHERE WILL REMAIN ANOMALOUSLY MOIST AND MODERATELY UNSTABLE
WHILE WEAK WEATHER DISTURBANCE CONTINUE TO AFFECT THE DESERT
SOUTHWEST. WENT WITH SLIGHT CHANCE POPS DURING THE LATE AFTN/EVENING
HOURS FOR SOUTH-CENTRAL AZ EACH DAY...BUT WOULD NOT BE SURPRISED IF
PRECIP CHANCES WILL ACTUALLY BE SOMEWHAT HIGHER THAN CURRENTLY
PORTRAYED.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...
ISOLATED THUNDERSTORMS THAT ARE NOW AFFECTING THE PHOENIX AREA ARE
EXPECTED TO DISSIPATE BY 400 AM. THESE STORMS ARE CURRENTLY TURNING
THE WINDS TO AN EASTERLY TO SOUTHEASTERLY DIRECTION. LIGHTER WINDS
ARE EXPECTED TO PREVAIL AFTER 400 AM WITH WESTERLY WINDS LIKELY TO
RETURN BY THIS AFTERNOON.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
NO THUNDERSTORM ACTIVITY EXPECTED OVER FAR SOUTHEAST CALIFORNIA AND
SOUTHWEST ARIZONA THE REST OF THE NIGHT...THOUGH A STRAY LIGHT
SHOWER CANT BE RULED OUT. OTHERWISE JUST SOME MINOR DEBRIS CLOUDS
AND WINDS FAVORING SOUTH AND SOUTHEAST DIRECTIONS. STORM ACTIVITY
TUESDAY AFTERNOON MAY IMPACT TAF SITES BUT TOO LOW A PROBABILITY TO
MENTION IN TAFS AT THIS POINT.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
SIGNIFICANT MONSOON MOISTURE WILL COVER THE REGION. A SLIGHT CHANCE
OF AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE MAINLY OVER
SOUTH CENTRAL ARIZONA...PARTICULARLY MOUNTAINS. MINIMUM RELATIVE
HUMIDITIES WILL RANGE FROM 20 TO 25 PERCENT...EXCEPT 15 TO 20
PERCENT IN IN SOUTHEAST CALIFORNIA. RELATIVELY LIGHT WINDS ARE
EXPECTED.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...AJ
PREVIOUS DISCUSSION...HIRSCH/DG
AVIATION...PERCHA/AJ
FIRE WEATHER...VASQUEZ
AREA FORECAST DISCUSSION...CORRECTED
NWS PHOENIX AZ
1010 PM MST MON SEP 3 2012
.UPDATE...UPDATED AVIATION SECTION...
.SYNOPSIS...
HIGH PRESSURE ALOFT WILL REMAIN CENTERED OVER OR NEAR NEW MEXICO
THROUGH MUCH OF THE UPCOMING WEEK. VERY MOIST AND MODERATELY
UNSTABLE AIR OVER THE AREA WILL LEAD TO STORM CHANCES ACROSS THE
REGION FOR MUCH OF THIS WEEK. LOCALLY HEAVY RAINFALL AND STRONG
WINDS ARE LIKELY WITH THE STRONGER STORMS.
&&
.DISCUSSION...
STORM ACTIVITY FOR THE NIGHT CONTINUES OVER FAR SOUTHEAST ARIZONA
BUT IS NOT WIDESPREAD. MADE UPDATES TO THE FORECAST TO DROP THE POPS
FROM MOST AREAS. A STRAY ECHO OR TWO LIE CLOSE ENOUGH TO SOUTHWEST
MARICOPA/NORTHWEST PINAL/SOUTHERN GILA COUNTIES THAT A SLIGHT CHANCE
WAS LEFT FOR THIS EVENING...GOING TO ZERO FOR THE OVERNIGHT HOURS.
DEEPER MOISTURE IS PROGGED TO SHIFT OVER SOUTHEAST ARIZONA TUESDAY
FOR A BETTER CHANCE OF STORMS OVER THE CENTRAL DESERTS. AS USUAL
THOUGH...FORECAST SOUNDINGS SUGGEST THAT OUTFLOWS WILL BE NECESSARY
TO OVERCOME SOME CONVECTIVE INHIBITION. SIMILAR SITUATION WEDNESDAY.
SOUTHEASTERLY STEERING FLOW WEDNESDAY MAY BE BEST OPPORTUNITY FOR
PHOENIX AREA. MEANWHILE...LOWER LEVELS OVER SOUTHEAST CALIFORNIA
START TO LOSE MOISTURE.
&&
.PREVIOUS DISCUSSION ISSUED 300 PM...
LATEST RAP ANALYZED A DIFFUSE TROUGH EXTENDING FROM SOUTHERN NM TO
HERMOSILLO MEXICO...THOUGH THIS IS DIFFICULT TO IDENTIFY ON WV
IMAGERY. STRONG STORMS HAVE DEVELOPED IN THE DIFLUENT REGION BETWEEN
THIS TROUGH AND AN ANTICYCLONE CENTERED NEAR THE WHITE MOUNTAINS.
FURTHER NORTH ACROSS THE MOGOLLON RIM...OROGRAPHICALLY-INDUCED
SHOWERS AND THUNDERSTORMS HAVE ALSO FORMED BUT CONTINUE TO DRIFT
NORTHEASTWARD TOWARDS THE CO PLATEAU WITHIN A 10 KT MEAN LAYER FLOW.
EARLIER MOISTURE SURGE ALONG THE GOC AND ACROSS YUMA AND THE
IMPERIAL VALLEY YIELDED HEAT INDICES BETWEEN 110 AND 115
DEGREES...BUT HAVE SINCE LOWERED AS THE ATMOSPHERE MIXES OUT.
LATEST MESOANALYSIS SHOWS MODERATELY STRONG CONVECTIVE INHIBITION
ACROSS MUCH OF THE FORECAST AREA...LARGELY DUE TO A RIDGE AND THE
ASSOCIATED WARM/DRY AIR IN THE 800-700 MB LAYER. MODEL SOUNDINGS
INDICATE THAT THIS LAYER WILL MOISTEN ACROSS WESTERN AZ THIS
AFTERNOON...WHICH WILL HELP TO ERODE THE CIN AND INITIATE ISOLATED
CONVECTION. NMM-B BASED WRF FROM UNIV OF AZ APPEARS TO HAVE THE BEST
HANDLE ON THE SHORT-TERM EVOLUTION AND SUGGESTS STORMS WILL FIRE
ACROSS YUMA AND LA PAZ COUNTIES THIS AFTERNOON. ISOLATED ACTIVITY IN
THE IMPERIAL VALLEY ALSO CANNOT BE RULED OUT...GIVEN THE
SOUTHWESTERLY STEERING FLOW AND PRESENCE OF CB/TCU ON VISIBLE
SATELLITE ALONG THE BAJA SPINE. ACROSS THE PHOENIX METRO AREA...THE
MAIN IMPACT APPEARS TO BE THE POTENTIAL BLOWING DUST FROM
THUNDERSTORMS TO THE SOUTH...THOUGH POPS REMAIN 5 TO 10 PERCENT
ABOVE THE CLIMATOLOGICAL AVERAGE.
IN THE SHORT TERM (MONDAY-WEDNESDAY)...EXPECT A DAY TO DAY INCREASE
IN STORM ACTIVITY...ESPECIALLY OVER AZ PORTION OF THE CWA. VERY
MOIST AIR MASS CURRENTLY EXISTS OVER NORTHWEST MEXICO. SYNOPTIC
PATTERN...WITH RATHER STRONG TROUGH OF LOW PRESSURE MOVING EAST
ACROSS SOUTH-CENTRAL CANADA WHILE A TROPICAL DISTURBANCE (NOW TS
JOHN) MOVES WEST JUST OFF THE SOUTHERN END OF BAJA
CALIFORNIA...CERTAINLY SUPPORTS A MOISTURE INCREASE OVER OUR
AREA...AND THE GFS/ECMWF/NAM CERTAINLY AGREE THE ATMOSPHERE WILL
MOISTEN SIGNIFICANTLY DURING THE NEXT 36 HRS.
WITH ATMOSPHERIC MOISTENING CONTINUING ON TUESDAY (ANOMALOUSLY HIGH
PRECIPITABLE WATER NEAR 2" BY THEN) AND MORE DIFLUENT UPPER LEVEL
FLOW OVER SOUTHEAST AZ BY TUESDAY AFTN...PRECIP CHANCE WILL BE A BIT
GREATER TUESDAY EVENING...ESPECIALLY OVER SOUTH-CENTRAL AZ. VERY
MOIST AND MODERATELY UNSTABLE ATMOSPHERE REMAINS IN PLACE ON
WEDNESDAY...AND PRECIP CHANCES WILL BE ENHANCED AS A WEAK WEATHER
DISTURBANCE MOVES WEST ACROSS SONORA. WITH SUCH HIGH ATMOSPHERIC
MOISTURE CONTENT...DECENT CAPE...AND WEAK STEERING FLOW...LOCALLY
HEAVY RAINFALL CAN BE EXPECTED...THOUGH STRONG/DAMAGING WINDS WILL
ALSO BE POSSIBLE.
IN THE EXTENDED PERIOD(THURSDAY-SUNDAY)...NUMERICAL MODELS INDICATE
ATMOSPHERE WILL REMAIN ANOMALOUSLY MOIST AND MODERATELY UNSTABLE
WHILE WEAK WEATHER DISTURBANCE CONTINUE TO AFFECT THE DESERT
SOUTHWEST. WENT WITH SLIGHT CHANCE POPS DURING THE LATE AFTN/EVENING
HOURS FOR SOUTH-CENTRAL AZ EACH DAY...BUT WOULD NOT BE SURPRISED IF
PRECIP CHANCES WILL ACTUALLY BE SOMEWHAT HIGHER THAN CURRENTLY
PORTRAYED.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...
ISOLATED THUNDERSTORMS THAT ARE NOW AFFECTING THE PHOENIX AREA ARE
EXPECTED TO DISSIPATE BY 400 AM. THESE STORMS ARE CURRENTLY TURNING
THE WINDS TO AN EASTERLY TO SOUTHEASTERLY DIRECTION. LIGHTER WINDS
ARE EXPECTED TO PREVAIL AFTER 400 AM WITH WESTERLY WINDS LIKELY TO
RETURN BY THIS AFTERNOON.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
NO THUNDERSTORM ACTIVITY EXPECTED OVER FAR SOUTHEAST CALIFORNIA AND
SOUTHWEST ARIZONA THE REST OF THE NIGHT...THOUGH A STRAY LIGHT
SHOWER CANT BE RULED OUT. OTHERWISE JUST SOME MINOR DEBRIS CLOUDS
AND WINDS FAVORING SOUTH AND SOUTHEAST DIRECTIONS. STORM ACTIVITY
TUESDAY AFTERNOON MAY IMPACT TAF SITES BUT TOO LOW A PROBABILITY TO
MENTION IN TAFS AT THIS POINT.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
SIGNIFICANT MONSOON MOISTURE WILL COVER THE REGION. A SLIGHT CHANCE
OF AFTERNOON AND EVENING THUNDERSTORMS WILL CONTINUE MAINLY OVER
SOUTH CENTRAL ARIZONA...PARTICULARLY MOUNTAINS. MINIMUM RELATIVE
HUMIDITIES WILL RANGE FROM 20 TO 25 PERCENT...EXCEPT 15 TO 20
PERCENT IN IN SOUTHEAST CALIFORNIA. RELATIVELY LIGHT WINDS ARE
EXPECTED.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...AJ
PREVIOUS DISCUSSION...HIRSCH/DG
AVIATION...PERCHA/AJ
FIRE WEATHER...VASQUEZ
AREA FORECAST DISCUSSION
NWS SAN JOAQUIN VALLEY - HANFORD CA
324 PM PDT TUE SEP 4 2012
.SYNOPSIS...
MOISTURE FROM THE TROPICS WILL STREAM INTO THE REGION THROUGH
THURSDAY PRODUCING ISOLATED SHOWERS AND THUNDERSTORMS TO PARTS OF
THE AREA. BY FRIDAY, DRIER AIR WILL MOVE IN FROM THE WEST,
BRINGING AN END TO THE THUNDERSTORM THREAT.
&&
.DISCUSSION...
SCT TO BKN CLOUDS ACROSS THE CENTRAL SJV AND INTO THE TULARE
COUNTY MOUNTAINS TODAY. TEMPERATURES ACROSS THE SJV ARE APPROACHING
THE CENTURY MARK IN A FEW LOCATIONS. NO PRECIP HAS BEEN REPORTED
WITH THE CLOUD COVER THIS AFTERNOON IN THE VALLEY AND ONLY A FEW
HUNDREDTHS IN THE TULARE COUNTY FOOTHILLS AND MOUNTAINS.
THE FORECAST CALLS FOR PARTLY CLOUDY SKIES TONIGHT OVER THE
CENTRAL CA INTERIOR. VISIBLE SATELLITE IMAGERY INDICATES A LINE OF
SHOWERS OFF THE NRN BAJA COAST THAT IS MOVING NORTH. SOME SHOWERS
HAVE DEVELOPED IN THE SOUTH LAND THIS AFTERNOON. THE KERN DESERT
AND MOUNTAINS REMAIN RAIN FREE THIS AFTERNOON AS RUC SHOWS STABLE
ATMS. A FEW LIGHTNING STRIKES ARE OCCURRING IN THE FRESNO COUNTY
MOUNTAINS ATTM AS A CLUSTER OF STORMS QUICKLY MOVES EAST.
SW FLOW ALOFT IS FORECAST TO CONTINUE THIS WEEK WITH RISING
HEIGHTS AND TEMPERATURES CONTINUING ABOVE NORMAL THROUGH THE
WEEKEND. THE UPPER RIDGE WILL MOVE INTO SRN CA BY SAT AND REMAIN
THERE UNTIL MONDAY BEFORE IT DRIFTS BACK TO THE EAST AS ANOTHER
SURGE OF MOISTURE APPROACHES THE AREA BY NEXT TUESDAY. THE ECMWF
IS MORE AGGRESSIVE WITH THE MOISTURE ON NEXT TUESDAY THAN THE GFS.
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL ACROSS THE CENTRAL CALIFORNIA INTERIOR
THROUGH 18Z WEDNESDAY.
&&
.AIR QUALITY ISSUES...
NONE.
&&
.CERTAINTY...
THE LEVEL OF CERTAINTY FOR DAYS 1 AND 2 IS MEDIUM.
THE LEVEL OF CERTAINTY FOR DAYS 3 THROUGH 7 IS MEDIUM.
THIS INFORMATION IS PROVIDED AS PART OF A TRIAL PROJECT CONDUCTED
BY THE NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD.
CERTAINTY LEVELS INCLUDE LOW...MEDIUM...AND HIGH. PLEASE VISIT
WWW.WEATHER.GOV/HNX/CERTAINTY.PHP /ALL LOWER CASE/ FOR ADDITIONAL
INFORMATION AND/OR TO PROVIDE FEEDBACK.
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
PUBLIC...JDB
AVN/FW...MOLINA
SYNOPSIS...WP
WEATHER.GOV/HANFORD
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
238 PM MDT TUE SEP 4 2012
.SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT)
ISSUED AT 238 PM MDT TUE SEP 4 2012
WATER VAPOR IMAGERY CLEARLY SHOWING MUCH DRIER AIR THAT HAS
FILTERED DOWN FROM THE NORTH OVERNIGHT WITH RH VALUES ACROSS TOP
THIRD OF THE FORECAST AREA IN THE TEENS. PWATS REMAIN NEAR .7 INCH
FOR THE SAN JUANS AND AREAS SOUTH SO SOME LIGHT SHOWERS OR QUICK
POP AND DROP STORM IS NOT OUT OF THE QUESTION THROUGH THE EVENING
HOURS. WATER VAPOR IS ALSO SHOWING SOME SMALL DISTURBANCES MOVING
THROUGH THE MEAN FLOW CAUSING SOME CONVECTION ACROSS ARIZONA AND
CENTRAL UTAH...POSSIBLY REACHING SOUTHEASTERN UTAH IN THE NEXT
HOUR OR TWO. DID INCREASE POPS FOR THAT AREA THROUGH THE EVENING
HOURS AS WELL AS KEEPING CURRENT POPS IN PLACE FOR THE SAN JUANS.
PLENTY OF SUNSHINE TO CONTINUE FOR THE REST OF THE FORECAST AREA
WHICH WILL PERSIST THROUGH REMAINDER OF SHORT TERM.
ANY CONVECTION SHOULD END NEAR SUNSET WITH CLEAR SKIES EXPECTED
OVERNIGHT. TEMPS SHOULD DROP TO PLEASANT CLIMATOLOGICAL NORMS FOR
MOST LOCALES.
NOT MUCH CHANGE WEDNESDAY WITH CHANCES FOR PRECIP CONTINUING TO
DECREASE WITH ONLY VERY ISOLD POPS OVER THE HIGHEST TERRAIN OF THE
SAN JUANS. SUNNY SKIES WILL BE THE RULE WITH TEMPS RUNNING ABOUT 4
TO 6 DEGREES ABOVE NORMAL. OVERNIGHT LOWS WILL STAY NEAR NORMAL.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 238 PM MDT TUE SEP 4 2012
A SHORTWAVE DISTURBANCE IS EXPECTED TO DROP ACROSS ID/MT ON
THURSDAY AND CLIP NE CO BY MIDDAY FRIDAY. AN ASSOCIATED COLD FRONT
SHOULD REACH NE UT/NW CO THU EVENING AND PUSH ACROSS THE REMAINDER
OF THE FORECAST AREA THURSDAY NIGHT. AS THE SHORTWAVE
APPROACHES...MOISTURE IS PULLED IN AHEAD OF IT FROM THE WEST FOR
INCREASING CLOUDS THURSDAY...WITH ISOLATED TO SCATTERED SHOWERS
DEVELOPING BY LATE AFTERNOON INTO EVENING. SOME INITIAL STORMS MAY
BE DRY...BUT MODELS FORECAST PRECIPITABLE WATER VALUES BETWEEN 1/2
TO 3/4 INCH BY THU EVENING...SO EXPECT STORMS TO WET UP.
DRIER AIR WILL BE MOVING IN ON NORTHWEST FLOW BY FRI AFTERNOON AND
CONTINUE THROUGH SATURDAY AS A HIGH PRESSURE RIDGE BUILDS OVER THE
GREAT BASIN. A PACIFIC TROUGH MOVES INLAND LATE THIS WEEKEND PULLING
UP A SLUG OF MOISTURE AHEAD OF IT AND PUSHING THE RIDGE EAST. THIS
SHOULD INCREASE THE CHANCE OF SHOWERS MONDAY AND TUESDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 238 PM MDT TUE SEP 4 2012
VFR CONDITIONS FOR ALL TAF SITES TODAY WITH KASE AND KEGE HAVING A
REMOTE CHANCE FOR A WEAK CELL TO MOVE CLOSE TO THE TERMINALS. SOME
GUSTY WINDS UP TO 40 MPH ARE POSSIBLE FROM THE CELLS. ASIDE FROM
THAT...PLENTY OF SUN EXPECTED WITH VFR PERSISTING THROUGH TOMORROW.
&&
.FIRE WEATHER...
ISSUED AT 238 PM MDT TUE SEP 4 2012
WIND GUSTS IN THE 20-25 MPH RANGE ACROSS THE NORTH THIS AFTERNOON
WITH A FEW SITES SHOWING A BIT STRONGER GUSTS. LOCALIZED AREAS
LIKELY TO SEE A BRIEF PERIOD OF CRITICAL RH AND/OR WIND GUSTS BUT
WIDESPREAD CRITICAL CONDITIONS ARE NOT EXPECTED. HIGH-RESOLUTION
HRRR AND RUC13 MODELS SHOW WIND GUSTS DIMINISHING QUICKLY EARLY THIS
EVENING.
NE UT/NW CO SHOULD CONTINUE TO REMAIN ON THE SOUTHERN FRINGE OF THE
STRONGER WINDS THROUGH WEDNESDAY. THURSDAY AFTERNOON MAY SEE A BIT
STRONGER WINDS ACROSS THE NORTH...20-30 MPH GUSTS...AS A SHORTWAVE
AND ASSOCIATED SURFACE COLD FRONT APPROACH FROM THEN NORTH.
HOWEVER...MOISTURE WILL ALSO BE INCREASING WITH AFTERNOON HUMIDITY
EXPECTED TO BOTTOM OUT RIGHT AROUND 15 PERCENT. WITH INCREASING
CLOUDS...WILL CONTINUE TO HOLD OFF ON ANY FIRE WEATHER HIGHLIGHTS
FOR NE UT/NW CO ALTHOUGH ISOLATED AREAS COULD SEE CRITICAL WIND/RH
CONDITIONS DEVELOP FOR A FEW HOURS THURS AFTERNOON. WILL CONTINUE
KEEPING A WATCH ON THIS. ISOLATED TO SCATTERED THUNDERSTORMS MAY BE
DRY INITIALLY THURS AFTERNOON BUT SHOULD WET UP BY THURS EVENING.
THE COLD FRONT SHOULD PUSH THROUGH THURS NIGHT.
&&
GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...TGR
LONG TERM...JAD
AVIATION...TGR
FIRE WEATHER...JAD
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1055 PM MDT MON SEP 3 2012
.SHORT TERM...(TODAY THROUGH TUESDAY NIGHT)
ISSUED AT 252 PM MDT MON SEP 3 2012
JET STREAM REMAINS OVERHEAD WITH STRONGEST JET STREAK HAVING MOVED
WELL EAST OVER SRN MN/NRN IA. CONVECTION CONTINUES TO FAVOR THE
ROAN/TAVAPUTS THIS AFTN IN RESPONSE TO DISTURBANCES MOVING
THROUGH MEAN FLOW AND ALSO FAVORABLE OROGRAPHICS. POT VORT FIELDS
ALSO FAVOR THIS AREA SO EVENTS PLAYING OUT AS EXPECTED. AS HAS
BEEN THE CASE LAST FEW DAYS...BIGGEST CONCERN WILL BE GUSTY
OUTFLOW WINDS REACHING 40 TO 45 MPH AND ALSO SOME SMALL HAIL. DID
EXPECT MORE CONVECTION DOWN SOUTH SINCE AVAILABLE PRECIP TABLE
WATER IS MUCH HIGHER. BELIEVE CONVECTION IS LIMITED FOR TWO
REASONS. FIRST...STEERING FLOW IS ALMOST FROM DUE WEST WHICH IS
NOT THE BEST DIRECTION FOR OROGRAPHICALLY INDUCED CONVECTION.
SECOND...AND MORE IMPORTANTLY...THERE IS NO REAL TRIGGER TO KICK
OFF SOME LIFT LIKE THERE IS UP NORTH.
SO FOR THE REMAINDER OF THE AFTERNOON...SOME MINOR DISCREPANCIES
HAVE CROPPED UP BETWEEN MODELS BUT HRRR IS DOING A REMARKABLE JOB
NAILING DOWN WHERE CONVECTION HAS AND IS OCCURRING. LATEST HRRR
GUIDANCE SUGGESTS SHOWERS AND STORMS WILL DIE DOWN BY 6PM WITH
VERY LITTLE IN THE WAY OF PRECIPITATION AFTER THAT. THIS DOES MAKE
SENSE AS MODELS ALSO CONTINUE TO DRY OUT ATMOSPHERE. FORECAST
FOLLOWS SUIT THOUGH NOT SO DRAMATICALLY WITH CONVECTION ENDING
AROUND SUNSET. CLEAR SKIES WILL BE DOMINANT OVERNIGHT ALLOWING LOW
TEMPS TO BE A BIT COOLER THAN SEEN THE LAST FEW DAYS THOUGH STILL
A DEGREE OR TWO ABOVE NORMAL.
ON TUESDAY ZONAL FLOW SETS UP FROM THE H3 LEVEL TO H7 WHICH
EFFECTIVELY CUTS OFF THE FLOW OF MOISTURE FROM THE SOUTH. THE MUCH
TOUTED DRIER AIR WILL FINALLY ARRIVE IF THE NAM12/GFS40 ARE TO BE
BELIEVED WHICH WILL GREATLY INHIBIT CONVECTION. KEPT POPS AS THEY
WERE WITH SOME VERY ISOLD SHOWERS AND STORMS POSSIBLE OVER SAN
JUANS AND TO SOME EXTENT CENTRAL MOUNTAINS THOUGH TREND IS TO KEEP
LOWERING POP AND QPF AMTS AND COVERAGE. THE REMAINDER OF THE
FORECAST AREA WILL SEE PLENTY OF SUNSHINE WITH SEASONAL
TEMPERATURES EXPECTED. OVERNIGHT...CLEAR SKIES EXPECTED WITH NEAR
NORMAL LOW TEMPERATURES.
.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 252 PM MDT MON SEP 3 2012
SOMEWHAT ACTIVE NORTHERN STREAM THE LAST HALF OF THE WEEK AS
SHORTWAVES ROTATING AROUND A CENTRAL CANADA LOW DROP INTO THE NRN
TIER STATES. FIRST SHORTWAVE MOVES INTO THE UPPER MIDWEST ON
WEDNESDAY... A SECOND DROPS DOWN ACROSS MT WED NIGHT...AND A THIRD
AND STRONGER ONE CLIPS NE CO LATE FRI. A RATHER WEAK WESTERLY UPPER
JET OVERHEAD ON WED STRENGTHENS THU-FRI AS THAT THIRD WAVE
APPROACHES...AND MAY RESULT IN STRONGER SURFACE WINDS ACROSS NE
UT/NW CO. BROAD HIGH PRESSURE DOMINATES THE SOUTHWEST STATES AND
FOUR CORNERS AND WILL BE MAIN INFLUENCE ON SE UT/SW CO. MODELS KEEP
ENOUGH MOISTURE PRESENT FOR ISOLATED TO PERHAPS SCATTERED
THUNDERSTORMS MAINLY OVER THE CENTRAL AND SOUTHERN MTNS THURSDAY.
THE SOUTHWEST UPPER HIGH BUILDS NORTHWEST INTO THE GREAT BASIN FRI
AND SAT AND SHOULD RESULT IN DRIER NW FLOW FOR OUR FORECAST AREA
THIS WEEKEND. MODELS SHOW A PACIFIC TROUGH REACHING THE NORTHWEST
COAST BY MONDAY...SHIFTING THE HIGH EAST AND ALLOWING MONSOONAL
MOISTURE TO RETURN NEXT MONDAY. CONFIDENCE BELOW AVERAGE ON THIS...
HOWEVER...GIVEN MODEL AND RUN-TO-RUN INCONSISTENCIES...SO WILL STAY
CONSERVATIVE WITH POPS FOR MONDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1054 PM MDT MON SEP 3 2012
DRY WEST TO NORTHWEST FLOW WILL KEEP VFR CONDITIONS IN PLACE
ACROSS THE REGION THROUGH LATE TUESDAY NIGHT.
&&
.FIRE WEATHER...
ISSUED AT 252 PM MDT MON SEP 3 2012
WIND IN GENERAL LOOKS TO REMAIN JUST BELOW CRITICAL LEVELS ACROSS
DAGGETT COUNTY AND NORTHERN DUCHESNE COUNTY /FWX ZONES 481 AND 485/
IN NE UT AND MOFFAT COUNTY /FWX ZONE 200/ IN NW CO TUESDAY
AFTERNOON. WIND GUSTS 20-25 MPH ARE PROBABLE DURING PEAK HEATING
TUESDAY AFTERNOON. WHILE LOCAL AREAS MAY SEE CRITICAL CONDITIONS
BELOW 8000-9000 FT DUE TO WIND GUSTS AND LOW RH...DO NOT THINK AREAL
COVERAGE OR DURATION IS ENOUGH TO WARRANT A FIRE WEATHER HIGHLIGHT
FOR NE UT/NW CO AT THIS TIME.
SOME CONCERN THAT WIND GUSTS COULD APPROACH/EXCEED CRITICAL LEVELS
ACROSS NE UT/NW CO ON THU AS A DISTURBANCE APPROACHING FROM THE NW
BEGINS TO STRENGTHEN WINDS ALOFT...WHICH COULD THEN MIX DOWN DURING
PEAK HEATING. HOWEVER...IT APPEARS THAT HUMIDITY WILL REMAIN ABOVE
CRITERIA THU AS MODELS CURRENTLY SHOWING SOME INCREASE IN MOISTURE.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...TGR
LONG TERM...JAD
AVIATION...JDC
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
510 AM EDT TUE SEP 4 2012
.SYNOPSIS...
A WARM FRONT EXTENDED EASTWARD FROM LOW PRESSURE IN THE OHIO
RIVER VALLEY TO MARYLAND AND DELAWARE AND THE ADJACENT COASTAL
WATERS EARLY THIS MORNING. THE LOW IS FORECAST TO DRIFT TO THE
NORTHEAST AND IT SHOULD PULL THE FRONT SLOWLY TO THE NORTH DURING
TODAY AND TONIGHT. AS THE LOW REACHES THE VICINITY OF MAINE AND
CANADA`S MARITIME PROVINCES ON WEDNESDAY NIGHT, IT IS EXPECTED TO
PULL A TRAILING FRONTAL BOUNDARY THROUGH OUR REGION. A COLD FRONT
FROM THE NORTHWEST IS FORECAST TO ARRIVE EARLY ON FRIDAY FOLLOWED
BY WEAK HIGH PRESSURE. SLOW MOVING LOW PRESSURE AND A FRONTAL
BOUNDARY FROM THE WEST MAY INFLUENCE OUR REGION OVER THE WEEKEND
AND INTO MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CNVTV ACTVTY DEFINITELY INCREASED DURG LATE EVE INTO THE
OVERNIGHT HOURS. IT HAS BEEN ORIENTED IN A MAINLY W-E BAND ACROSS
SRN AND SE PA INTO SRN NJ. NOT EXACTLY CLEAR WHAT IS DRIVING THIS
LATEST ROUND EXCEPT THAT THE AMS CONTS TO BE VERY MOIST AND SMWHT
UNSTABLE... ESPCLY ACRS THE CNTRL AND SRN PARTS OF OUR FCST AREA.
LATEST RAP MODEL DOES SHOW GOOD UVV OVER THE AREA. STORMS ARE
PRODUCING LCLLY HVY RAIN AND SOME FLOODING...BUT FORTUNATELY THE
WORST OF IT SEEMS TO BE OVER SMWHT SPARSELY POPULATED AREAS IN SRN
NJ.
CNVTN IS EXPECTED TO CONT FOR A FEW MORE HRS WITH PERHAPS A SLOW
NWD SHIFT. OTRW HAVE GENLY MAINTAINED THE CURRENT FCST WITH LIKELY
POPS FOR MOST OF THE AREA THROUGH TUESDAY. ELY WINDS EARLY THIS
MORN SHOULD INCR AND BECOME SLY BY AFTN. MAX TEMPS ARE A BLEND OF
MAV/MET GUIDANCE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
LOW PRES OVER ERN OH IS FCST TO TRACK NEWD INTO UPSTATE NY DURG
THIS PD...WITH A CDFNT TRAILING SWWD. HWVR OUR FCST AREA WILL
REMAIN IN THE MOIST TROPICAL AMS AHD OF THE FNT AND THUS THE
POTENTIAL FOR HEAVY SHOWERS AND TSTMS WILL CONT. THERE SHOULD BE
ENOUGH OF A PRES GRADIENT TO MAINTAIN LIGHT SLY WINDS OVERNIGHT.
MIN TEMPS SHOULD BE SIMILAR TO EARLY THIS MORNING.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
ON WEDNESDAY MORNING, THE AXIS OF DEEP MOISTURE WILL EXTEND
THROUGH OUR FORECAST AREA. PRECIPITABLE WATER VALUES SHOULD BE IN
EXCESS OF 2 INCHES AT MOST LOCATIONS. A LOW LEVEL JET IS EXPECTED
TO EXTEND FROM THE CAROLINAS TO NEW ENGLAND AT THAT TIME. BOTH
FEATURES ARE ANTICIPATED TO DRIFT EASTWARD ON WEDNESDAY. HOWEVER,
THE THREAT OF HEAVY RAIN WILL REMAIN THROUGH MUCH OF THE DAY,
DECREASING SLOWLY FROM WEST TO EAST. AS A RESULT, THE FLASH FLOOD
WATCH WILL BE EXTENDED INTO WEDNESDAY EVENING.
A MID LEVEL SHORT WAVE OVER THE DAKOTAS EARLY THIS MORNING IS
FORECAST TO WORK ITS WAY TO THE EAST. THE FEATURE IS EXPECTED TO
PASS OVERHEAD FROM WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING. IT
WILL HELP TO KICK THE DEEP MOISTURE OFF THE COAST ON WEDNESDAY
NIGHT, FURTHER DECREASING THE POTENTIAL FOR HEAVY RAIN IN OUR
REGION.
FOR THURSDAY, THERE WILL REMAIN SOME INSTABILITY IN OUR REGION AS
ANOTHER MID LEVEL SHORT WAVE APPROACHES FROM THE NORTHWEST. AS A
RESULT, WE WILL KEEP THE MENTION OF A CHANCE OF SHOWERS AND
THUNDERSTORMS. THE SHORT WAVE IS EXPECTED TO PASS OVERHEAD ON
THURSDAY AFTERNOON. A SURFACE COLD FRONT ASSOCIATED WITH THE
FEATURE SHOULD ARRIVE FOR LATE THURSDAY NIGHT AND EARLY FRIDAY.
WEAK HIGH PRESSURE AND DRY AIR ARE EXPECTED TO FOLLOW FOR FRIDAY
INTO FRIDAY NIGHT.
A MID LEVEL TROUGH IS ANTICIPATED TO DIG OVER THE EASTERN HALF OF
THE COUNTRY FOR THE WEEKEND AND INTO THE EARLY PART OF THE NEW
WEEK. CONDITIONS ARE FORECAST TO BECOME UNSETTLED AGAIN DURING
THAT PERIOD WITH A CHANCE OF PRECIPITATION.
TEMPERATURES MAY BE SLIGHTLY ABOVE NORMAL FOR WEDNESDAY THROUGH
FRIDAY AND NEAR NORMAL FOR SATURDAY THROUGH MONDAY.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
IFR CIGS SHOULD PREVAIL OVERNIGHT BUT VSBYS WILL REMAIN HIGH...
EXCEPT IN HEAVY SHOWERS OR ISOLD TSTMS. THESE CONDS WILL PERSIST
INTO TUE MORNING BUT SHOULD IMPROVE SMWHAT BY MID MORNING. MAINLY
VFR CONDS ARE EXPECTED BY TUE AFTN. HWVR...SHWRS/TSTMS FROM TIME
TO TIME WILL RESULT IN PERIODS OF MVFR TO IFR CIGS/VSBYS BUT IN
GENERAL THESE SHOULD NOT LAST VERY LONG AT ANY GIVEN SITE. TAFS
WILL BE UPDATED BASED ON SHORT-TERM FCSTS WITH AS MUCH LEAD TIME
AS POSSIBLE.
WINDS OVERNIGHT WILL BE LIGHT ELY BUT ARE FCST TO BECOME SLY BY
MID DAY TUE AND BECOME A LITTLE STRONGER.
OUTLOOK...
WEDNESDAY...SHOWERS LIKELY WITH A CHANCE OF THUNDERSTORMS. THERE
IS THE POTENTIAL FOR PERIODS OF MODERATE TO HEAVY RAIN ACCOMPANIED
BY MVFR OR IFR CONDITIONS. MVFR OR IFR CONDITIONS ARE ALSO
POSSIBLE IN MORNING FOG, HAZE AND LOW CLOUDS.
WEDNESDAY NIGHT AND THURSDAY...MAINLY VFR WITH A CHANCE OF
SHOWERS AND THUNDERSTORMS. MVFR OR IFR CONDITIONS ARE ALSO
POSSIBLE IN LATE NIGHT AND EARLY MORNING FOG, HAZE AND LOW CLOUDS.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...MAINLY VFR.
SATURDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS.
&&
.MARINE...
AFTER FURTHER REVIEW...DECIDED TO GO AHEAD AND ISSUE A SCA FOR
COASTAL WATERS BEGINNING THIS EVE AND CONTG THROUGH WED. THIS WILL
BE PRIMARILY FOR SEAS DUE TO A COMBO OF WIND WAVES AND INCRG SELY
SWELL...ALTHO THERE COULD BE OCNL GUSTS TO 25 KT IN SW FLOW. THE WW3
SHOWS SEAS UP TO 7 FT AT THE OUTER EDGE OF OUR COASTAL WATERS ON
WED MORN...WHICH COULD BE A BIT OVERDONE BUT IT SEEMS PRUDENT AT
THIS POINT TO GO AHEAD WITH THE SCA.
SCATTERED SHOWER AND TSTM ACTVTY WILL CONT WITH LCLY POOR VSBYS
AND HIGHER WINDS NEAR TSTMS.
OUTLOOK...
A WARM FRONT IS FORECAST TO LIFT SLOWLY OVER THE COASTAL WATERS
OF DELAWARE AND NEW JERSEY DURING TODAY WITH ANOTHER FRONTAL
BOUNDARY ARRIVING FROM THE WEST ON WEDNESDAY NIGHT. A COLD FRONT
FROM THE NORTHWEST IS ANTICIPATED FOR EARLY FRIDAY. WIND SPEEDS
AND GUSTS SHOULD REMAIN LESS THAN 25 KNOTS THROUGH THE PERIOD.
FROM WEDNESDAY THROUGH SATURDAY, LONG PERIOD SWELLS FROM DISTANT
TROPICAL SYSTEM LESLIE ARE FORECAST TO AFFECT THE COASTAL WATERS
OF DELAWARE AND NEW JERSEY. WAVE HEIGHTS ON OUR OCEAN WATERS
SHOULD BE 5 FEET OR GREATER DURING THAT PERIOD WITH A SMALL CRAFT
ADVISORY LIKELY.
&&
.RIP CURRENTS...
LONG PERIOD SWELLS FROM DISTANT TROPICAL SYSTEM LESLIE ARE
FORECAST TO AFFECT THE COASTS OF DELAWARE AND NEW JERSEY INTO AT
LEAST THE EARLY PART OF NEXT WEEK. AS A RESULT, A PROLONGED PERIOD
WITH A MODERATE TO HIGH RISK OF RIP CURRENTS IS ANTICIPATED.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...FLASH FLOOD WATCH THROUGH WEDNESDAY EVENING FOR PAZ067>071.
NJ...FLASH FLOOD WATCH THROUGH WEDNESDAY EVENING FOR NJZ015>019.
DE...FLASH FLOOD WATCH THROUGH WEDNESDAY EVENING FOR DEZ001.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 PM EDT
WEDNESDAY FOR ANZ450>455.
&&
$$
SYNOPSIS...IOVINO
NEAR TERM...AMC
SHORT TERM...AMC
LONG TERM...IOVINO
AVIATION...AMC/IOVINO
MARINE...AMC/IOVINO
RIP CURRENTS...
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
430 AM EDT TUE SEP 4 2012
.SYNOPSIS...
A WARM FRONT EXTENDED EASTWARD FROM LOW PRESSURE IN THE OHIO
RIVER VALLEY TO MARYLAND AND DELAWARE AND THE ADJACENT COASTAL
WATERS EARLY THIS MORNING. THE LOW IS FORECAST TO DRIFT TO THE
NORTHEAST AND IT SHOULD PULL THE FRONT SLOWLY TO THE NORTH DURING
TODAY AND TONIGHT. AS THE LOW REACHES THE VICINITY OF MAINE AND
CANADA`S MARITIME PROVINCES ON WEDNESDAY NIGHT, IT IS EXPECTED TO
PULL A TRAILING FRONTAL BOUNDARY THROUGH OUR REGION. A COLD FRONT
FROM THE NORTHWEST IS FORECAST TO ARRIVE EARLY ON FRIDAY FOLLOWED
BY WEAK HIGH PRESSURE. SLOW MOVING LOW PRESSURE AND A FRONTAL
BOUNDARY FROM THE WEST MAY INFLUENCE OUR REGION OVER THE WEEKEND
AND INTO MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CNVTV ACTVTY DEFINITELY INCREASED DURG LATE EVE INTO THE
OVERNIGHT HOURS. IT HAS BEEN ORIENTED IN A MAINLY W-E BAND ACROSS
SRN AND SE PA INTO SRN NJ. NOT EXACTLY CLEAR WHAT IS DRIVING THIS
LATEST ROUND EXCEPT THAT THE AMS CONTS TO BE VERY MOIST AND SMWHT
UNSTABLE... ESPCLY ACRS THE CNTRL AND SRN PARTS OF OUR FCST AREA.
LATEST RAP MODEL DOES SHOW GOOD UVV OVER THE AREA. STORMS ARE
PRODUCING LCLLY HVY RAIN AND SOME FLOODING...BUT FORTUNATELY THE
WORST OF IT SEEMS TO BE OVER SMWHT SPARSELY POPULATED AREAS IN SRN
NJ.
CNVTN IS EXPECTED TO CONT FOR A FEW MORE HRS WITH PERHAPS A SLOW
NWD SHIFT. OTRW HAVE GENLY MAINTAINED THE CURRENT FCST WITH LIKELY
POPS FOR MOST OF THE AREA THROUGH TUESDAY. ELY WINDS EARLY THIS
MORN SHOULD INCR AND BECOME SLY BY AFTN. MAX TEMPS ARE A BLEND OF
MAV/MET GUIDANCE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
LOW PRES OVER ERN OH IS FCST TO TRACK NEWD INTO UPSTATE NY DURG
THIS PD...WITH A CDFNT TRAILING SWWD. HWVR OUR FCST AREA WILL
REMAIN IN THE MOIST TROPICAL AMS AHD OF THE FNT AND THUS THE
POTENTIAL FOR HEAVY SHOWERS AND TSTMS WILL CONT. THERE SHOULD BE
ENOUGH OF A PRES GRADIENT TO MAINTAIN LIGHT SLY WINDS OVERNIGHT.
MIN TEMPS SHOULD BE SIMILAR TO EARLY THIS MORNING.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
ON WEDNESDAY MORNING, THE AXIS OF DEEP MOISTURE WILL EXTEND
THROUGH OUR FORECAST AREA. PRECIPITABLE WATER VALUES SHOULD BE IN
EXCESS OF 2 INCHES AT MOST LOCATIONS. A LOW LEVEL JET IS EXPECTED
TO EXTEND FROM THE CAROLINAS TO NEW ENGLAND AT THAT TIME. BOTH
FEATURES ARE ANTICIPATED TO DRIFT EASTWARD ON WEDNESDAY. HOWEVER,
THE THREAT OF HEAVY RAIN WILL REMAIN THROUGH MUCH OF THE DAY,
DECREASING SLOWLY FROM WEST TO EAST. AS A RESULT, THE FLASH FLOOD
WATCH WILL BE EXTENDED INTO WEDNESDAY EVENING.
A MID LEVEL SHORT WAVE OVER THE DAKOTAS EARLY THIS MORNING IS
FORECAST TO WORK ITS WAY TO THE EAST. THE FEATURE IS EXPECTED TO
PASS OVERHEAD FROM WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING. IT
WILL HELP TO KICK THE DEEP MOISTURE OFF THE COAST ON WEDNESDAY
NIGHT, FURTHER DECREASING THE POTENTIAL FOR HEAVY RAIN IN OUR
REGION.
FOR THURSDAY, THERE WILL REMAIN SOME INSTABILITY IN OUR REGION AS
ANOTHER MID LEVEL SHORT WAVE APPROACHES FROM THE NORTHWEST. AS A
RESULT, WE WILL KEEP THE MENTION OF A CHANCE OF SHOWERS AND
THUNDERSTORMS. THE SHORT WAVE IS EXPECTED TO PASS OVERHEAD ON
THURSDAY AFTERNOON. A SURFACE COLD FRONT ASSOCIATED WITH THE
FEATURE SHOULD ARRIVE FOR LATE THURSDAY NIGHT AND EARLY FRIDAY.
WEAK HIGH PRESSURE AND DRY AIR ARE EXPECTED TO FOLLOW FOR FRIDAY
INTO FRIDAY NIGHT.
A MID LEVEL TROUGH IS ANTICIPATED TO DIG OVER THE EASTERN HALF OF
THE COUNTRY FOR THE WEEKEND AND INTO THE EARLY PART OF THE NEW
WEEK. CONDITIONS ARE FORECAST TO BECOME UNSETTLED AGAIN DURING
THAT PERIOD WITH A CHANCE OF PRECIPITATION.
TEMPERATURES MAY BE SLIGHTLY ABOVE NORMAL FOR WEDNESDAY THROUGH
FRIDAY AND NEAR NORMAL FOR SATURDAY THROUGH MONDAY.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
IFR CIGS SHOULD PREVAIL OVERNIGHT BUT VSBYS WILL REMAIN HIGH...
EXCEPT IN HEAVY SHOWERS OR ISOLD TSTMS. THESE CONDS WILL PERSIST
INTO TUE MORNING BUT SHOULD IMPROVE SMWHAT BY MID MORNING. MAINLY
VFR CONDS ARE EXPECTED BY TUE AFTN. HWVR...SHWRS/TSTMS FROM TIME
TO TIME WILL RESULT IN PERIODS OF MVFR TO IFR CIGS/VSBYS BUT IN
GENERAL THESE SHOULD NOT LAST VERY LONG AT ANY GIVEN SITE. TAFS
WILL BE UPDATED BASED ON SHORT-TERM FCSTS WITH AS MUCH LEAD TIME
AS POSSIBLE.
WINDS OVERNIGHT WILL BE LIGHT ELY BUT ARE FCST TO BECOME SLY BY
MID DAY TUE AND BECOME A LITTLE STRONGER.
OUTLOOK...
WEDNESDAY...SHOWERS LIKELY WITH A CHANCE OF THUNDERSTORMS. THERE
IS THE POTENTIAL FOR PERIODS OF MODERATE TO HEAVY RAIN ACCOMPANIED
BY MVFR OR IFR CONDITIONS. MVFR OR IFR CONDITIONS ARE ALSO
POSSIBLE IN MORNING FOG, HAZE AND LOW CLOUDS.
WEDNESDAY NIGHT AND THURSDAY...MAINLY VFR WITH A CHANCE OF
SHOWERS AND THUNDERSTORMS. MVFR OR IFR CONDITIONS ARE ALSO
POSSIBLE IN LATE NIGHT AND EARLY MORNING FOG, HAZE AND LOW CLOUDS.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...MAINLY VFR.
SATURDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS.
&&
.MARINE...
SELY WINDS OVER THE COASTAL WATERS WILL BECOME MORE SLY TODAY AS
THE FNTL BNDRY ACROSS DELMARVA GRDLY LIFTS NWD. WINDS AND SEAS ARE
EXPECTED TO INCREASE A BIT TONIGHT AND COULD APPROACH SCA CONDS AT
TIMES. SITN APPEARS MARGINAL HWVR SO WILL HOLD OFF ISSUING ANY
ADVISORIES FOR NOW. SCATTERED SHOWER AND TSTM ACTVTY WILL CONT WITH
LCLLY POOR VSBYS AND HIGHER WINDS NEAR TSTMS.
OUTLOOK...
A WARM FRONT IS FORECAST TO LIFT SLOWLY OVER THE COASTAL WATERS
OF DELAWARE AND NEW JERSEY DURING TODAY WITH ANOTHER FRONTAL
BOUNDARY ARRIVING FROM THE WEST ON WEDNESDAY NIGHT. A COLD FRONT
FROM THE NORTHWEST IS ANTICIPATED FOR EARLY FRIDAY. WIND SPEEDS
AND GUSTS SHOULD REMAIN LESS THAN 25 KNOTS THROUGH THE PERIOD.
FROM WEDNESDAY THROUGH SATURDAY, LONG PERIOD SWELLS FROM DISTANT
TROPICAL SYSTEM LESLIE ARE FORECAST TO AFFECT THE COASTAL WATERS
OF DELAWARE AND NEW JERSEY. WAVE HEIGHTS ON OUR OCEAN WATERS
SHOULD BE 5 FEET OR GREATER DURING THAT PERIOD WITH A SMALL CRAFT
ADVISORY LIKELY.
&&
.RIP CURRENTS...
LONG PERIOD SWELLS FROM DISTANT TROPICAL SYSTEM LESLIE ARE
FORECAST TO AFFECT THE COASTS OF DELAWARE AND NEW JERSEY INTO AT
LEAST THE EARLY PART OF NEXT WEEK. AS A RESULT, A PROLONGED PERIOD
WITH A MODERATE TO HIGH RISK OF RIP CURRENTS IS ANTICIPATED.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...FLASH FLOOD WATCH THROUGH WEDNESDAY EVENING FOR PAZ067>071.
NJ...FLASH FLOOD WATCH THROUGH WEDNESDAY EVENING FOR NJZ015>019.
DE...FLASH FLOOD WATCH THROUGH WEDNESDAY EVENING FOR DEZ001.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...IOVINO
NEAR TERM...AMC
SHORT TERM...AMC
LONG TERM...IOVINO
AVIATION...AMC/IOVINO
MARINE...AMC/IOVINO
RIP CURRENTS...IOVINO
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
405 AM EDT TUE SEP 4 2012
.SYNOPSIS...
07Z WATER VAPOR AND H4 RAP ANALYSIS SHOW A COMPLEX UPPER LEVEL
PATTERN OVER THE SOUTHEAST CONUS THIS MORNING. FORECAST AREA IS
SITUATED BETWEEN A DISTURBANCE/SHORTWAVE DROPPING SOUTHWARD OUT OF
AL/GA/MS...AND A POTENT CLOSED UPPER LOW SPINNING JUST OFF THE
FLORIDA EAST COAST. UPPER LEVEL MOISTURE FIELDS ARE ALSO QUITE
COMPLEX WITH WV IMAGERY SHOWING A BAND OF SIGNIFICANTLY LOWER UPPER
TROPOSPHERIC MOISTURE WRAPPING AROUND THE NORTHERN AND WESTERN SIDES
OF THE UPPER LOW CIRCULATION. THE POSITION AND STRENGTH OF THIS DRY
AIR WILL PLAY A PART IN WHERE THE BEST CHANCES FOR SHOWERS/STORMS
WILL OCCUR LATER TODAY.
AT THE SURFACE...SUBTROPICAL RIDGE IS A BIT UNDEFINED...HOWEVER BEST
GUESS ANALYSIS WOULD PLACE THE AXIS THROUGH THE CENTRAL FL
PENINSULA. VERY LITTLE IN THE WAY OF RADAR RETURNS ACROSS THE
FORECAST AREA THIS MORNING. MOST OF THE ACTIVITY IS LOCATED TO OUR
NORTH AND SOUTH ASSOCIATED WITH THE 2 DISTURBANCES MENTIONED ABOVE.
&&
.SHORT TERM (TODAY THROUGH THURSDAY)...
TODAY...UPPER LEVEL ENERGY TO OUR NORTHWEST WILL CONTINUE
TO SINK SOUTHWARD OVER THE FL PANHANDLE AND OVER THE NORTH-CENTRAL
GULF OF MEXICO BY THE END OF THE DAY. AT THE SAME TIME WILL BE
WATCHING THE UPPER LOW CENTERED JUST EAST OF MIAMI BEGIN TO VERY
SLOWLY MIGRATE NORTHWARD. OUR FORECAST AREA WILL REMAIN SOMEWHERE IN
THE MIDDLE MAKING THE FORECAST A BIT CHALLENGING...ESPECIALLY IN
REGARDS TO RAIN CHANCES. IN GENERAL EXPECTING THE BEST SYNOPTIC
SUPPORT FOR LIFT ASSOCIATED WITH THE NORTHERN ENERGY TO REMAIN TO
THE NORTH OF LEVY COUNTY TOWARD THE WESTERN BIG BEND/PANHANDLE
AREAS. AT THE SAME TIME...THE MOST SUPPORTIVE MOISTURE FIELDS AND
MID-LEVEL COLD POOL ASSOCIATED WITH THE UPPER LOW WILL BE ALONG THE
FLORIDA EAST COAST. WITH THIS IN MIND...WONT DEVIATE FAR FROM THE
MAV RAIN CHANCES FOR THE NATURE COAST/TAMPA BAY AREA ZONES. WILL
BUMP RAIN CHANCES UP 10-20% FURTHER INLAND AND SOUTHWARD DOWN TOWARD
FORT MYERS IN CLOSER PROXIMITY TO THE INSTABILITY UNDER THE COLD
POOL.
WEDNESDAY...THE OVERALL SYNOPTIC PATTERN IN THE UPPER LEVELS WILL
NOT CHANGE SIGNIFICANTLY WITH OUR REGION REMAINING IN THE SQUEEZE
BETWEEN 2 PIECES OF UPPER LEVEL ENERGY. THE SUBTROPICAL RIDGE AXIS
IS FORECAST TO DROP A BIT FURTHER SOUTHWARD WHICH WILL ACT TO TURN
OUR LOW LEVEL FLOW MORE TO AN ONSHORE SOUTHWEST DIRECTION. GLOBAL
GUIDANCE IS ALSO HINTING THAT SOME OF DRY AIR ALOFT WILL BE
DIMINISHING MAKING THE COLUMN LESS HOSTILE TO DEEP CONVECTION. THE
LOW LEVEL SW FLOW IS CLIMO FAVORED FOR THE DEVELOPMENT OF WIDELY SCT
NOCTURNAL SHOWERS OVER THE COASTAL WATERS AND WILL ADD THIS
POTENTIAL TO THE GRIDS DURING THE SECOND HALF OF WEDNESDAY NIGHT.
THURSDAY...FORECAST IS OF LOWER CONFIDENCE THAN USUAL FOR THE DAY
THREE PERIOD AS GLOBAL GUIDANCE IS NOT IN GOOD AGREEMENT REGARDING
THE EVENTUAL EVOLUTION OF THE DISTURBANCE DROPPING OFF THE FL
PANHANDLE IN THE NORTH-CENTRAL GULF. GFS HAS A MORE SHEARED SYSTEM
WITH ONLY AN OPEN TROUGH AT THE SURFACE. THE ECMWF ON THE OTHER HAND
HOLDS ONTO A STRONGER VORTICITY LOBE IN THE UPPER LEVELS WHICH
SUPPORTS A CLOSED SURFACE LOW REFLECTION. THESE 2 SOLUTIONS PRODUCE
VERY DIFFERENT WIND/MOISTURE FIELDS OVER THE EASTERN GULF AND FL
PENINSULA. VERY DIFFICULT TO SAY WHICH MODEL HAS A BETTER HANDLE ON
THE SITUATION. UNTIL THINGS BECOME MORE CERTAIN...WILL RUN A BLEND
OF THE MAV/SREF FOR THE THURSDAY FORECAST.
&&
.LONG TERM (FRIDAY THROUGH NEXT MONDAY)...
A TROUGH AXIS WITH ORIGINS BACK TO THE REMNANTS OF ISAAC PHASED W/
NRN STREAM STREAM ENERGY WILL DIG INTO THE NE GULF THROUGH THE END
OF THE WEEK. MODELS ARE NOT IN GOOD AGREEMENT ON WHAT HAPPENS BEYOND
THAT. THE ECMWF HAS CONSISTENTLY SPUN UP A SFC LOW PRESSURE SYSTEM
JUST NE OF THE REGION WHILE THE GFS SHEARS THE ENERGY APART AND
KEEPS MORE OF A DISORGANIZED TROUGH. THE NAM 12 SEEMS ON BOARD WITH
THE ECMWF AS IT ALSO SHOWS A CLOSED LOW BY FRI. EITHER
WAY...MOISTURE POOLED ALONG AND SOUTH OF THIS SYSTEM WILL MOVE IN
OFF THE NE GULF LEADING TO INCREASE IN TROPICAL SHRA AND TSTMS FOR
THE WEEKEND...BUT WHICH SOLN PANS OUT WILL OBVIOUSLY HAVE MAJOR
IMPLICATIONS ON EXACTLY HOW MUCH IMPACT THIS SYSTEM WILL HAVE. GIVEN
THE UNCERTAINTY...WILL HOLD CLOSER TO A GFS SOLN WITH POPS
INCREASING INTO THE SCT RANGE FOR THE WEEKEND. A MUCH STRONGER AND
MORE AMPLIFIED MID LEVEL TROUGH WILL DEVELOP OVER THE WEEKEND ACROSS
THE ERN HALF OF THE COUNTRY. THE 00Z GFS HAS TRENDED MORE TOWARDS A
LARGE CLOSED LOW SIMILAR TO THE ECMWF AND THIS WOULD ACTUALLY BRING
THE FIRST COLD FRONT OF THE SEASON THROUGH THE AREA BEFORE STALLING.
PREVIOUS RUNS STALLED THE BOUNDARY A BIT FURTHER NORTH BUT STILL
BROUGHT THE BOUNDARY INTO THE CEN FL...AND CLIMATOLOGICALLY THIS IS
PROBABLY A BETTER SOLN FOR DAY 7-8 OF THE FORECAST. SO WILL KEEP
SCT/CHC POPS GOING INTO MON FOR NOW...AT LEAST ACROSS SRN HALF OF
THE CWA. INCREASE IN PRECIP AND ONSHORE WINDS WILL HELP KEEP HIGHS
DOWN SOME OVER THE WEEKEND AND WILL ALSO PROVIDE AN INCREASED RISK
OF RIP CURRENTS TO THE AREA.
&&
.AVIATION...
WILL INCLUDE VCTS FOR LATE AFTN AND EARLY EVENING FOR LAL AND SRN
SITES TO COVER ISOLD TO SCT TSTMS IN THESE AREAS. THERE IS AN
OUTSIDE CHC OF MVFR VSBYS IN SRN SITES THIS MORNING AND WED
MORNING...BUT PROBS ARE TO LOW TO RESTRICT TAFS AND WILL THEREFORE
STICK WITH VFR FORECAST FOR THE NEXT 24 HOURS.
&&
.MARINE...
THE SUBTROPICAL RIDGE AXIS WILL SETTLE SOUTHWARD THE NEXT COUPLE OF
DAYS. WINDS AND SEAS WILL REMAIN LOW THROUGH WEDNESDAY...THEN BEING
TO INCREASE DURING THURSDAY AND FRIDAY AS A TROUGH OR WEAK AREA OF
LOW PRESSURE APPROACHES FROM THE WEST.
&&
.FIRE WEATHER...
THE FORECAST THROUGH MIDWEEK WILL FEATURE A MORE TYPICAL SUMMER
PATTERN WITH WIDELY SCATTERED AFTERNOON/EVENING STORMS. RELATIVE
HUMIDITY VALUES WILL REMAIN ABOVE CRITICAL VALUES AND NO SIGNIFICANT
FIRE WEATHER CONCERNS ARE ANTICIPATED.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 90 75 90 76 / 20 10 30 20
FMY 92 75 90 74 / 30 20 40 20
GIF 93 73 91 73 / 30 20 30 10
SRQ 89 75 89 76 / 20 10 30 20
BKV 92 70 91 70 / 20 10 30 20
SPG 91 78 89 77 / 20 10 30 20
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...GITTINGER
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
201 AM EDT TUE SEP 4 2012
.PREV DISCUSSION... /ISSUED 952 PM EDT MON SEP 3 2012/
UPDATE...
HAVE MADE SEVERAL UPDATES TO THE GRIDS THROUGH THE EVENING...
MAINLY TO ADJUST POPS TO ACCOUNT FOR CONVECTIVE TRENDS. REDUCED
POPS NORTHWEST AND INCREASED IN A LINE ROUGHLY FROM AHN TO CSG
WHERE CONVECTION LINGERED THROUGH THE EVENING...WITH A SLOW
INCREASING TREND NORTHWEST OVER NIGH. HRRR AND OTHER HIRES GUIDANCE
STILL INDICATING THAT CONVECTION FROM ALABAMA WILL WORK ITS WAY
INTO GEORGIA...ESPECIALLY WHAT HAS BEEN DEVELOPING IN NORTHEAST
ALABAMA. DID REDUCE THUNDER WORDING FOR THE OVERNIGHT PERIOD.
TEMPS THROUGH THE EVENING DUE TO THE RAIN...AND OVERNIGHT LOWS MAY
BE A LITTLE TOO HIGH. HAVE MADE SOME MINOR ADJUSTMENTS BUT WITH
DEWPOINTS SO HIGH DO NOT FEEL COMFORTABLE LOWERING MINS ANY MORE.
TDP
SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
/ISSUED 334 PM EDT MON SEP 3 2012/
REMNANTS OF ISAAC STILL SPINNING NEAR THE IN/KY BORDER THIS
AFTERNOON. TWO RAIN BANDS MOVING THROUGH GA AT THE MOMENT. THE FIRST
ONE IS DOWN ALONG THE GA COAST WITH THE SECOND NOW MOVING THROUGH
THE ATL/AHN AREAS. MAINLY SHOWERS WITH THIS BAND BUT THERE ARE SOME
ISOLATED THUNDERSTORMS . THESE STORMS ARE NOT SEVERE BUT THEY ARE
INCREASING IN INTENSITY AS THEY MOVE INTO MORE UNSTABLE AIR ACROSS
CENTRAL GA. INSTABILITIES HAVE INCREASED INTO THE 1500-2500 J/KG
RANGE ACROSS CENTRAL GA AND WILL SUPPORT SOME STRONG STORMS. MODELS
INDICATING POSSIBLE MCS DEVELOPMENT OVERNIGHT JUST WEST OF THE CWA.
HAVE KEPT POPS HIGH THROUGH TUESDAY...WITH GENERALLY LIKELY ACROSS
MUCH OF THE CWA. ALTHOUGH BEST DESTABILIZATION IS OCCURRING RIGHT
NOW...THERE SHOULD BE ENOUGH INSTABILITY TO SUPPORT ISOLATED TO
SCATTERED THUNDERSTORMS THROUGH THE OVERNIGHT HOURS.
MOST PLACES WILL SEE PRECIPITATION AMOUNTS OF 1-2 INCHES THROUGH THE
SHORT TERM. FLASH FLOOD GUIDANCE WELL ABOVE THIS SO DO NOT
ANTICIPATE ANY ISSUES. AS FOR TEMPERATURES...MAV GUIDANCE HA BEEN
RUNNING A BIT COLD ON MIN TEMPS AND A BIT WARM ON MAX TEMPS. HAVE
MADE SLIGHT ADJUSTMENTS TO COMPENSATE FOR THIS.
01
LONG TERM /WEDNESDAY THROUGH MONDAY/...
/ISSUED 334 PM EDT MON SEP 3 2012/
LATEST EXTENDED GUIDANCE SHOWS BEST MOISTURE HANGING AROUND A
LITTLE LONGER INTO WEDNESDAY AND THURSDAY AND ONLY CHANGE WAS TO
BUMP UP INTO LOW LIKELY/HIGH CHANCE RANGE. REMAINDER OF THE
EXTENDED REMAINS UNCHANGED.
DEESE
TROPICAL MOISTURE BECOMES STRETCHED OUT ACROSS THE CWA THROUGH
WEDNESDAY WITH SOME HINT AT DRYING THURSDAY INTO FRIDAY AS THE
UPPER RIDGE NOSES EASTWARD. HAVE NOT REMOVED POPS FOR THE BRIEF
DRIER PERIOD...JUST REDUCED THEM OVER MUCH OF THE CWA. BY THE
WEEKEND BOTH MODELS SHOW A SIGNIFICANT CLOSED LOW DEVELOPING
VICINITY OF THE OHIO VALLEY. THIS KEEPS THE UNSETTLED WEATHER OVER
THE CWA AND HAVE CONTINUED WITH CHANCE OR SLIGHT CHANCE POPS.
MODEL MAX TEMPERATURES LOOKED A BIT HIGH GIVEN THE UPPER PATTERN
SO HAVE TWEAKED THEM DOWN A BIT MOST AREAS.
41
&&
.AVIATION...
06Z UPDATE...
SCATTERED LIGHT TO MODERATE RAIN SHOWERS CONTINUE THIS MORNING
ACROSS MUCH OF THE AREA. IFR CIGS BEGINNING TO DEVELOP...AND
EXPECT WIDESPREAD IFR CIGS BY 09Z. CIGS IMPROVE TO MVFR BY
15Z...AND SHOULD REMAIN LOW END VFR THROUGH THE AFTERNOON. -SHRA
EXPECTED OFF AND ON THROUGH THE DAY...WITH BEST CHANCE FOR TS
AFTER 18Z. HAVE GONE PREVAILING TS AT THIS TIME...BUT WILL LIKELY
CHANGE THIS TO TEMPO FOR 12Z TAF...AS PER DIRECTIVE. SW WINDS
THROUGH THE PERIOD...EXCEPT AHN WITH SSE WINDS. SPEEDS SHOULD BE
7-9KTS THROUGH THE DAY...THEN 5KTS OR LESS OVERNIGHT.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM ON ALL ELEMENTS.
31
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 86 71 87 71 / 60 50 50 30
ATLANTA 84 72 86 73 / 60 40 40 30
BLAIRSVILLE 79 65 82 65 / 70 50 40 20
CARTERSVILLE 85 71 86 68 / 70 50 40 20
COLUMBUS 88 73 89 74 / 70 40 50 30
GAINESVILLE 82 71 85 71 / 70 50 50 30
MACON 89 72 89 72 / 60 40 50 30
ROME 86 71 87 69 / 70 40 30 20
PEACHTREE CITY 85 71 86 69 / 60 40 40 30
VIDALIA 91 73 90 74 / 60 40 40 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...31
LONG TERM....41
AVIATION...31
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1236 PM CDT TUE SEP 4 2012
.DISCUSSION...
ISSUED 937 AM CDT TUE SEP 4 2012
WEAKENING SHORT-WAVE TROUGH HAS SPREAD A BAND OF MID-LEVEL
CLOUDINESS INTO CENTRAL AND WESTERN ILLINOIS THIS MORNING. DESPITE
THE PRESENCE OF THIS FORCING MECHANISM...PREVAILING HIGH PRESSURE
HAS PREVENTED MUCH PRECIP FROM REACHING THE AREA. 14Z/9AM RADAR
MOSAIC SHOWS A LINE OF SHOWERS/STORMS EXTENDING FROM NORTH OF
SAINT LOUIS WESTWARD ACROSS CENTRAL MISSOURI...HOWEVER THIS PRECIP
IS DISSIPATING AS IT PUSHES FURTHER EAST INTO THE SURFACE RIDGE
AXIS. NEITHER THE 11Z HRRR NOR THE 12Z NAM ARE HANDLING THE
CURRENT SITUATION VERY WELL AT ALL...WITH BOTH MODELS INDICATING A
GOOD DEAL OF PRECIP ACROSS THE WESTERN KILX CWA THIS MORNING.
BASED ON CURRENT SATELLITE/RADAR AND THE PRESENCE OF SURFACE HIGH
PRESSURE...HAVE REJECTED THE HIGH-RES MODEL SOLUTION IN FAVOR OF
ONLY ISOLATED SHOWERS/THUNDER TODAY. HAVE ALREADY SENT A ZONE
UPDATE TO LOWER POPS AND REMOVE MENTION OF MORNING FOG ACROSS THE
E/SE.
BARNES
&&
.AVIATION...
ISSUED 1236 PM CDT TUE SEP 4 2012
VFR CONDITIONS WILL PREVAIL THROUGH THE ENTIRE 18Z TAF PERIOD. A
BAND OF MID/HIGH CLOUDS WILL CONTINUE TO DRIFT EASTWARD ACROSS THE
AREA THIS AFTERNOON...WHILE A CU-FIELD DEVELOPS AT LOW-LEVELS.
CU-RULE AND LATEST SATELLITE IMAGERY SUGGEST BKN CEILINGS AOA
4000FT POSSIBLE ACROSS THE EAST. HAVE INCLUDED A TEMPO GROUP FOR
BKN CU AT KCMI...BUT HAVE KEPT SKIES SCT FURTHER WEST AT THE
REMAINING TERMINALS. ONCE MID/HIGH CLOUDS SHIFT FURTHER EAST AND
DIURNAL CU DISSIPATES...CLEAR SKIES WILL BE THE RULE TONIGHT.
FORECAST SOUNDINGS SHOW INCREASING MID/HIGH CLOUDS ONCE AGAIN BY
WEDNESDAY MORNING...AS A COLD FRONT APPROACHES FROM THE WEST. ANY
LOWER CLOUDS AND SCATTERED CONVECTION WILL LIKELY HOLD OFF UNTIL
AFTER 18Z. WINDS WILL INITIALLY BE LIGHT/VARIABLE THIS AFTERNOON
AND TONIGHT...BUT WILL BECOME S/SE AT 5 TO 10KT AHEAD OF THE
APPROACHING FRONT WEDNESDAY MORNING.
BARNES
&&
.PREV DISCUSSION...
ISSUED 330 AM CDT TUE SEP 4 2012
SHORT TERM...TODAY THROUGH FRIDAY NIGHT
SOME FOG PRESENT OVER EASTERN IL EAST OF I-55 WHERE SKIES
CURRENTLY CLEAR AND WILL CONTINUE PATCHY FOG UNTIL 9 AM OVER
EASTERN IL. MID/HIGH CLOUDS SPREADING EAST FROM IA AND NORTHERN MO
INTO CENTRAL/NW IL EARLY THIS MORNING WITH A CLUSTER OF SHOWERS
AND THUNDERSTORMS OVER NORTHERN MO AND OVER SOUTHERN LAKE MI AND
NEAR CHICAGO. HRRR MODELS WAS HANDLING QPF THE BEST THIS MORNING
WHICH BRINGS THE CONVECTION FROM NORTHERN MO EASTWARD INTO CENTRAL
IL AND WEAKENS IT THIS MORNING. WILL CARRY POPS OF 20-40% TODAY
AND HIGHEST WEST OF SPRINGFIELD. ISOLATED SHOWERS AND
THUNDERSTORMS POSSIBLE THIS AFTERNOON IN UNSTABLE HUMID AIRMASS
WITH DEWPOINTS STILL IN THE LOWER 70S. SPC KEEPS SLIGHT RISK NW
OF IL TODAY. HIGHS IN THE UPPER 80S AND LOWER 90S AGAIN TODAY.
HAVE 20-30% CHANCE OF SHOWERS AND THUNDERSTORMS INTO WESTERN AREAS
OVERNIGHT WHILE PATCHY FOG POSSIBLE OVER EASTERN IL AGAIN AFTER
MIDNIGHT. MODELS HAVE TRENDED A BIT SLOWER WITH A STRONGER COLD
FRONT MOVING SE INTO CENTRAL IL WED AFTERNOON/EVENING. SPC
CONTINUES SLIGHT RISK ACROSS MUCH OF CENTRAL IL NW OF I-70 WED
AFTERNOON AND EARLY EVENING UNTIL SUNSET. AIRMASS GETS UNSTABLE
AGAIN BY WED AFTERNOON WITH CAPES 2000-3000 J/KG WHILE BEST WIND
SHEAR AND SHORT WAVE ENERGY IS NORTH OF CENTRAL IL. ADDED 20-30%
CHANCE OF CONVECTION OVER EASTERN IL WED EVENING ESPECIALLY EARLY
WED EVENING UNTIL SUNSET. ANOTHER VERY WARM AND HUMID DAY WED WITH
HIGHS IN THE UPPER 80S AND LOWER 90S.
DRY CONDITIONS EXPECTED THU WITH A FAIR AMOUNT OF SUNSHINE AS WEAK
HIGH PRESSURE SETTLES INTO IL BY SUNSET THU...WITH SOME INCREASING
CLOUDS FROM THE WEST LATER IN THE DAY. HIGHS IN THE LOW TO MID 80S
AND WARMEST BY LAWRENCEVILLE WITH 87F.
ANOTHER FAIRLY STRONG NORTHERN STREAM SHORT WAVE DIVES INTO THE
MIDWEST BY FRI RETURNING A GOOD CHANCE OF SHOWERS AND A FEW
THUNDERSTORMS. THIS TO ALSO BRING COOLER WEATHER LATER THIS WEEK.
LONG TERM...SATURDAY THROUGH MONDAY NIGHT
THE ENSEMBLE MODELS CONTINUE TO SHOW A STRONG UPPER LEVEL TROF
DIGGING SOUTHEAST THROUGH THE MIDWEST AND GREAT LAKES REGION LATE
THIS WEEK. THERE ARE STILL DIFFERENCES AMONG THE INDIVIDUAL
MEMBERS ON WHAT HAPPENS WITH THIS TROUGH THIS WEEKEND...WITH SOME
MEMBERS KEEPING THE TROUGH MORE PROGRESSIVE AND PUSHING IT EAST OF
THE AREA BY SUNDAY MORNING...WHILE OTHERS CUTOFF THE TROUGH OVER
THE OHIO VALLEY INTO NEXT MONDAY. FOR NOW WILL USE A BLEND OF
MODEL SOLUTIONS AND STICK CLOSE TO ALLBLEND POPS IN THE EXTENDED
FOR THIS WEEKEND...WITH HIGHER POPS SAT AND SHIFTING MORE INTO
EASTERN IL SUNDAY...AND DRY MONDAY. BELOW NORMAL TEMPERATURES
BY 5-10 DEGREES FOR THE HIGHS EXPECTED THIS WEEKEND AND GRADUALLY
MODIFY DURING NEXT WORK WEEK.
KH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
937 AM CDT TUE SEP 4 2012
.DISCUSSION...
ISSUED 937 AM CDT TUE SEP 4 2012
WEAKENING SHORT-WAVE TROUGH HAS SPREAD A BAND OF MID-LEVEL
CLOUDINESS INTO CENTRAL AND WESTERN ILLINOIS THIS MORNING. DESPITE
THE PRESENCE OF THIS FORCING MECHANISM...PREVAILING HIGH PRESSURE
HAS PREVENTED MUCH PRECIP FROM REACHING THE AREA. 14Z/9AM RADAR
MOSAIC SHOWS A LINE OF SHOWERS/STORMS EXTENDING FROM NORTH OF
SAINT LOUIS WESTWARD ACROSS CENTRAL MISSOURI...HOWEVER THIS PRECIP
IS DISSIPATING AS IT PUSHES FURTHER EAST INTO THE SURFACE RIDGE
AXIS. NEITHER THE 11Z HRRR NOR THE 12Z NAM ARE HANDLING THE
CURRENT SITUATION VERY WELL AT ALL...WITH BOTH MODELS INDICATING A
GOOD DEAL OF PRECIP ACROSS THE WESTERN KILX CWA THIS MORNING.
BASED ON CURRENT SATELLITE/RADAR AND THE PRESENCE OF SURFACE HIGH
PRESSURE...HAVE REJECTED THE HIGH-RES MODEL SOLUTION IN FAVOR OF
ONLY ISOLATED SHOWERS/THUNDER TODAY. HAVE ALREADY SENT A ZONE
UPDATE TO LOWER POPS AND REMOVE MENTION OF MORNING FOG ACROSS THE
E/SE.
BARNES
&&
.AVIATION...
ISSUED 605 AM CDT TUE SEP 4 2012
COVERAGE OF MVFR AND LOCAL IFR VSBYS IN FOG OVER THE NEXT COUPLE
OF HOURS...AND THEN THE TSRA THREAT TODAY THE MAIN FORECAST
CONCERNS.
A WEAK WEATHER DISTURBANCE TRACKING ACROSS THE LOWER GREAT LAKES
THIS MORNING HAS PRODUCED SOME SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS THE SOUTHERN GREAT LAKES WITH A SECONDARY AREA OF STORMS
OVER PARTS OF NORTHERN MISSOURI. SHORT RANGE MODELS SUGGEST AS THE
UPPER WAVE MOVES ACROSS OUR AREA THIS MORNING...IT WILL BRING A
FEW OF THE SHOWERS AND THUNDERSTORMS INTO OUR AREA BUT COVERAGE
LOOKS TO BE QUITE LIMITED...NOT MUCH MORE THAN A VCSH/VCTS MENTION
AT THIS POINT. WHAT FOG WE DO SEE OVER THE NEXT COUPLE OF HOURS
SHOULD BE GONE BY 14 OR 15Z...WITH SOME SCATTERED CUMULUS WITH
BASES AROUND 4000 FEET AND SCT-BKN AC INTO THE AFTERNOON HOURS.
WINDS WILL BE LIGHT FROM A SOUTHERLY DIRECTION TODAY WITH SPEEDS
OF 10KTS OR LESS...WITH LIGHT AND VARIABLE WINDS AGAIN FOR TONIGHT.
MAY SEE VSBYS DROP AGAIN TO MVFR LATER TONIGHT AS SOME PATCHY FOG
FORMS AFTR 05Z.
SMITH
&&
.PREV DISCUSSION...
ISSUED 330 AM CDT TUE SEP 4 2012
SHORT TERM...TODAY THROUGH FRIDAY NIGHT
SOME FOG PRESENT OVER EASTERN IL EAST OF I-55 WHERE SKIES
CURRENTLY CLEAR AND WILL CONTINUE PATCHY FOG UNTIL 9 AM OVER
EASTERN IL. MID/HIGH CLOUDS SPREADING EAST FROM IA AND NORTHERN MO
INTO CENTRAL/NW IL EARLY THIS MORNING WITH A CLUSTER OF SHOWERS
AND THUNDERSTORMS OVER NORTHERN MO AND OVER SOUTHERN LAKE MI AND
NEAR CHICAGO. HRRR MODELS WAS HANDLING QPF THE BEST THIS MORNING
WHICH BRINGS THE CONVECTION FROM NORTHERN MO EASTWARD INTO CENTRAL
IL AND WEAKENS IT THIS MORNING. WILL CARRY POPS OF 20-40% TODAY
AND HIGHEST WEST OF SPRINGFIELD. ISOLATED SHOWERS AND
THUNDERSTORMS POSSIBLE THIS AFTERNOON IN UNSTABLE HUMID AIRMASS
WITH DEWPOINTS STILL IN THE LOWER 70S. SPC KEEPS SLIGHT RISK NW
OF IL TODAY. HIGHS IN THE UPPER 80S AND LOWER 90S AGAIN TODAY.
HAVE 20-30% CHANCE OF SHOWERS AND THUNDERSTORMS INTO WESTERN AREAS
OVERNIGHT WHILE PATCHY FOG POSSIBLE OVER EASTERN IL AGAIN AFTER
MIDNIGHT. MODELS HAVE TRENDED A BIT SLOWER WITH A STRONGER COLD
FRONT MOVING SE INTO CENTRAL IL WED AFTERNOON/EVENING. SPC
CONTINUES SLIGHT RISK ACROSS MUCH OF CENTRAL IL NW OF I-70 WED
AFTERNOON AND EARLY EVENING UNTIL SUNSET. AIRMASS GETS UNSTABLE
AGAIN BY WED AFTERNOON WITH CAPES 2000-3000 J/KG WHILE BEST WIND
SHEAR AND SHORT WAVE ENERGY IS NORTH OF CENTRAL IL. ADDED 20-30%
CHANCE OF CONVECTION OVER EASTERN IL WED EVENING ESPECIALLY EARLY
WED EVENING UNTIL SUNSET. ANOTHER VERY WARM AND HUMID DAY WED WITH
HIGHS IN THE UPPER 80S AND LOWER 90S.
DRY CONDITIONS EXPECTED THU WITH A FAIR AMOUNT OF SUNSHINE AS WEAK
HIGH PRESSURE SETTLES INTO IL BY SUNSET THU...WITH SOME INCREASING
CLOUDS FROM THE WEST LATER IN THE DAY. HIGHS IN THE LOW TO MID 80S
AND WARMEST BY LAWRENCEVILLE WITH 87F.
ANOTHER FAIRLY STRONG NORTHERN STREAM SHORT WAVE DIVES INTO THE
MIDWEST BY FRI RETURNING A GOOD CHANCE OF SHOWERS AND A FEW
THUNDERSTORMS. THIS TO ALSO BRING COOLER WEATHER LATER THIS WEEK.
LONG TERM...SATURDAY THROUGH MONDAY NIGHT
THE ENSEMBLE MODELS CONTINUE TO SHOW A STRONG UPPER LEVEL TROF
DIGGING SOUTHEAST THROUGH THE MIDWEST AND GREAT LAKES REGION LATE
THIS WEEK. THERE ARE STILL DIFFERENCES AMONG THE INDIVIDUAL
MEMBERS ON WHAT HAPPENS WITH THIS TROUGH THIS WEEKEND...WITH SOME
MEMBERS KEEPING THE TROUGH MORE PROGRESSIVE AND PUSHING IT EAST OF
THE AREA BY SUNDAY MORNING...WHILE OTHERS CUTOFF THE TROUGH OVER
THE OHIO VALLEY INTO NEXT MONDAY. FOR NOW WILL USE A BLEND OF
MODEL SOLUTIONS AND STICK CLOSE TO ALLBLEND POPS IN THE EXTENDED
FOR THIS WEEKEND...WITH HIGHER POPS SAT AND SHIFTING MORE INTO
EASTERN IL SUNDAY...AND DRY MONDAY. BELOW NORMAL TEMPERATURES
BY 5-10 DEGREES FOR THE HIGHS EXPECTED THIS WEEKEND AND GRADUALLY
MODIFY DURING NEXT WORK WEEK.
KH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
611 AM CDT TUE SEP 4 2012
.DISCUSSION...
ISSUED 330 AM CDT TUE SEP 4 2012
SHORT TERM...TODAY THROUGH FRIDAY NIGHT
SOME FOG PRESENT OVER EASTERN IL EAST OF I-55 WHERE SKIES
CURRENTLY CLEAR AND WILL CONTINUE PATCHY FOG UNTIL 9 AM OVER
EASTERN IL. MID/HIGH CLOUDS SPREADING EAST FROM IA AND NORTHERN MO
INTO CENTRAL/NW IL EARLY THIS MORNING WITH A CLUSTER OF SHOWERS
AND THUNDERSTORMS OVER NORTHERN MO AND OVER SOUTHERN LAKE MI AND
NEAR CHICAGO. HRRR MODELS WAS HANDLING QPF THE BEST THIS MORNING
WHICH BRINGS THE CONVECTION FROM NORTHERN MO EASTWARD INTO CENTRAL
IL AND WEAKENS IT THIS MORNING. WILL CARRY POPS OF 20-40% TODAY
AND HIGHEST WEST OF SPRINGFIELD. ISOLATED SHOWERS AND
THUNDERSTORMS POSSIBLE THIS AFTERNOON IN UNSTABLE HUMID AIRMASS
WITH DEWPOINTS STILL IN THE LOWER 70S. SPC KEEPS SLIGHT RISK NW
OF IL TODAY. HIGHS IN THE UPPER 80S AND LOWER 90S AGAIN TODAY.
HAVE 20-30% CHANCE OF SHOWERS AND THUNDERSTORMS INTO WESTERN AREAS
OVERNIGHT WHILE PATCHY FOG POSSIBLE OVER EASTERN IL AGAIN AFTER
MIDNIGHT. MODELS HAVE TRENDED A BIT SLOWER WITH A STRONGER COLD
FRONT MOVING SE INTO CENTRAL IL WED AFTERNOON/EVENING. SPC
CONTINUES SLIGHT RISK ACROSS MUCH OF CENTRAL IL NW OF I-70 WED
AFTERNOON AND EARLY EVENING UNTIL SUNSET. AIRMASS GETS UNSTABLE
AGAIN BY WED AFTERNOON WITH CAPES 2000-3000 J/KG WHILE BEST WIND
SHEAR AND SHORT WAVE ENERGY IS NORTH OF CENTRAL IL. ADDED 20-30%
CHANCE OF CONVECTION OVER EASTERN IL WED EVENING ESPECIALLY EARLY
WED EVENING UNTIL SUNSET. ANOTHER VERY WARM AND HUMID DAY WED WITH
HIGHS IN THE UPPER 80S AND LOWER 90S.
DRY CONDITIONS EXPECTED THU WITH A FAIR AMOUNT OF SUNSHINE AS WEAK
HIGH PRESSURE SETTLES INTO IL BY SUNSET THU...WITH SOME INCREASING
CLOUDS FROM THE WEST LATER IN THE DAY. HIGHS IN THE LOW TO MID 80S
AND WARMEST BY LAWRENCEVILLE WITH 87F.
ANOTHER FAIRLY STRONG NORTHERN STREAM SHORT WAVE DIVES INTO THE
MIDWEST BY FRI RETURNING A GOOD CHANCE OF SHOWERS AND A FEW
THUNDERSTORMS. THIS TO ALSO BRING COOLER WEATHER LATER THIS WEEK.
LONG TERM...SATURDAY THROUGH MONDAY NIGHT
THE ENSEMBLE MODELS CONTINUE TO SHOW A STRONG UPPER LEVEL TROF
DIGGING SOUTHEAST THROUGH THE MIDWEST AND GREAT LAKES REGION LATE
THIS WEEK. THERE ARE STILL DIFFERENCES AMONG THE INDIVIDUAL
MEMBERS ON WHAT HAPPENS WITH THIS TROUGH THIS WEEKEND...WITH SOME
MEMBERS KEEPING THE TROUGH MORE PROGRESSIVE AND PUSHING IT EAST OF
THE AREA BY SUNDAY MORNING...WHILE OTHERS CUTOFF THE TROUGH OVER
THE OHIO VALLEY INTO NEXT MONDAY. FOR NOW WILL USE A BLEND OF
MODEL SOLUTIONS AND STICK CLOSE TO ALLBLEND POPS IN THE EXTENDED
FOR THIS WEEKEND...WITH HIGHER POPS SAT AND SHIFTING MORE INTO
EASTERN IL SUNDAY...AND DRY MONDAY. BELOW NORMAL TEMPERATURES
BY 5-10 DEGREES FOR THE HIGHS EXPECTED THIS WEEKEND AND GRADUALLY
MODIFY DURING NEXT WORK WEEK.
KH
&&
.AVIATION...
ISSUED 605 AM CDT TUE SEP 4 2012
COVERAGE OF MVFR AND LOCAL IFR VSBYS IN FOG OVER THE NEXT COUPLE
OF HOURS...AND THEN THE TSRA THREAT TODAY THE MAIN FORECAST
CONCERNS.
A WEAK WEATHER DISTURBANCE TRACKING ACROSS THE LOWER GREAT LAKES
THIS MORNING HAS PRODUCED SOME SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS THE SOUTHERN GREAT LAKES WITH A SECONDARY AREA OF STORMS
OVER PARTS OF NORTHERN MISSOURI. SHORT RANGE MODELS SUGGEST AS THE
UPPER WAVE MOVES ACROSS OUR AREA THIS MORNING...IT WILL BRING A
FEW OF THE SHOWERS AND THUNDERSTORMS INTO OUR AREA BUT COVERAGE
LOOKS TO BE QUITE LIMITED...NOT MUCH MORE THAN A VCSH/VCTS MENTION
AT THIS POINT. WHAT FOG WE DO SEE OVER THE NEXT COUPLE OF HOURS
SHOULD BE GONE BY 14 OR 15Z...WITH SOME SCATTERED CUMULUS WITH
BASES AROUND 4000 FEET AND SCT-BKN AC INTO THE AFTERNOON HOURS.
WINDS WILL BE LIGHT FROM A SOUTHERLY DIRECTION TODAY WITH SPEEDS
OF 10KTS OR LESS...WITH LIGHT AND VARIABLE WINDS AGAIN FOR TONIGHT.
MAY SEE VSBYS DROP AGAIN TO MVFR LATER TONIGHT AS SOME PATCHY FOG
FORMS AFTR 05Z.
SMITH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
330 AM CDT TUE SEP 4 2012
.DISCUSSION...
ISSUED 330 AM CDT TUE SEP 4 2012
SHORT TERM...TODAY THROUGH FRIDAY NIGHT
SOME FOG PRESENT OVER EASTERN IL EAST OF I-55 WHERE SKIES
CURRENTLY CLEAR AND WILL CONTINUE PATCHY FOG UNTIL 9 AM OVER
EASTERN IL. MID/HIGH CLOUDS SPREADING EAST FROM IA AND NORTHERN MO
INTO CENTRAL/NW IL EARLY THIS MORNING WITH A CLUSTER OF SHOWERS
AND THUNDERSTORMS OVER NORTHERN MO AND OVER SOUTHERN LAKE MI AND
NEAR CHICAGO. HRRR MODELS WAS HANDLING QPF THE BEST THIS MORNING
WHICH BRINGS THE CONVECTION FROM NORTHERN MO EASTWARD INTO CENTRAL
IL AND WEAKENS IT THIS MORNING. WILL CARRY POPS OF 20-40% TODAY
AND HIGHEST WEST OF SPRINGFIELD. ISOLATED SHOWERS AND
THUNDERSTORMS POSSIBLE THIS AFTERNOON IN UNSTABLE HUMID AIRMASS
WITH DEWPOINTS STILL IN THE LOWER 70S. SPC KEEPS SLIGHT RISK NW
OF IL TODAY. HIGHS IN THE UPPER 80S AND LOWER 90S AGAIN TODAY.
HAVE 20-30% CHANCE OF SHOWERS AND THUNDERSTORMS INTO WESTERN AREAS
OVERNIGHT WHILE PATCHY FOG POSSIBLE OVER EASTERN IL AGAIN AFTER
MIDNIGHT. MODELS HAVE TRENDED A BIT SLOWER WITH A STRONGER COLD
FRONT MOVING SE INTO CENTRAL IL WED AFTERNOON/EVENING. SPC
CONTINUES SLIGHT RISK ACROSS MUCH OF CENTRAL IL NW OF I-70 WED
AFTERNOON AND EARLY EVENING UNTIL SUNSET. AIRMASS GETS UNSTABLE
AGAIN BY WED AFTERNOON WITH CAPES 2000-3000 J/KG WHILE BEST WIND
SHEAR AND SHORT WAVE ENERGY IS NORTH OF CENTRAL IL. ADDED 20-30%
CHANCE OF CONVECTION OVER EASTERN IL WED EVENING ESPECIALLY EARLY
WED EVENING UNTIL SUNSET. ANOTHER VERY WARM AND HUMID DAY WED WITH
HIGHS IN THE UPPER 80S AND LOWER 90S.
DRY CONDITIONS EXPECTED THU WITH A FAIR AMOUNT OF SUNSHINE AS WEAK
HIGH PRESSURE SETTLES INTO IL BY SUNSET THU...WITH SOME INCREASING
CLOUDS FROM THE WEST LATER IN THE DAY. HIGHS IN THE LOW TO MID 80S
AND WARMEST BY LAWRENCEVILLE WITH 87F.
ANOTHER FAIRLY STRONG NORTHERN STREAM SHORT WAVE DIVES INTO THE
MIDWEST BY FRI RETURNING A GOOD CHANCE OF SHOWERS AND A FEW
THUNDERSTORMS. THIS TO ALSO BRING COOLER WEATHER LATER THIS WEEK.
LONG TERM...SATURDAY THROUGH MONDAY NIGHT
THE ENSEMBLE MODELS CONTINUE TO SHOW A STRONG UPPER LEVEL TROF
DIGGING SOUTHEAST THROUGH THE MIDWEST AND GREAT LAKES REGION LATE
THIS WEEK. THERE ARE STILL DIFFERENCES AMONG THE INDIVIDUAL
MEMBERS ON WHAT HAPPENS WITH THIS TROUGH THIS WEEKEND...WITH SOME
MEMBERS KEEPING THE TROUGH MORE PROGRESSIVE AND PUSHING IT EAST OF
THE AREA BY SUNDAY MORNING...WHILE OTHERS CUTOFF THE TROUGH OVER
THE OHIO VALLEY INTO NEXT MONDAY. FOR NOW WILL USE A BLEND OF
MODEL SOLUTIONS AND STICK CLOSE TO ALLBLEND POPS IN THE EXTENDED
FOR THIS WEEKEND...WITH HIGHER POPS SAT AND SHIFTING MORE INTO
EASTERN IL SUNDAY...AND DRY MONDAY. BELOW NORMAL TEMPERATURES
BY 5-10 DEGREES FOR THE HIGHS EXPECTED THIS WEEKEND AND GRADUALLY
MODIFY DURING NEXT WORK WEEK.
KH
&&
.AVIATION...
ISSUED 1154 PM CDT MON SEP 3 2012
NONE OF THE SHORT RANGE MODELS HAVE A VERY GOOD HANDLE ON THE
CLOUDS OR PRECIPITATION THAT WAS OCCURRING JUST BEFORE 05Z. THE
BIGGEST QUESTION OVERNIGHT WILL BE THE VISIBILITY AFTER 10Z. MOST
TAF SITES IN CENTRAL AND EASTERN IL WILL HAVE PLENTY OF LOW LEVEL
MOISTURE AND CALM/VERY LIGHT WIND. THE CLOUD COVER MAY NOT BE AS
EXTENSIVE AS PREVIOUSLY THOUGHT. THUS...MOST AREAS SHOULD SEE
THEIR VISIBILITY DROP TO MVFR LEVELS BY 10-11Z.
ACROSS EASTERN IL THE MID/UPPER LEVEL CLOUDS WILL ARRIVE LATER AND
THE CROSSOVER TEMPS INDICATE A BETTER CHANCE FOR FOG OVERNIGHT.
THUS...THE VSBY SHOULD DROP TO MVFR LEVELS FIRST...THEN INTO THE
IFR CATEGORY JUST BEFORE DAYBREAK.
THE BEST CHANCE FOR WIDELY SCATTERED SHOWERS WILL BE AFTER
DAYBREAK AS A WEAK SHORTWAVE MOVES TOWARD THE AREA...SO PUSHED BACK
THE VCSH A FEW HOURS TO REFLECT THIS.
MILLER
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
800 PM EDT WED SEP 5 2012
.UPDATE/AVIATION...
STABLE POST OUTFLW BUBBLE HAS CURTAILED ANY UPSTREAM CONV DVLPMNT
WITHIN RTN LL THETA-E WEDGE ACRS ERN IA/WRN-NRN IL THIS EVENING AHD
OF CDFNT AND DOUBT THAT WILL CHG GOING FORWARD THROUGH TONIGHT.
DROPPED PRIOR TRIMMED POPS FM AFTN ISSUANCE FORWARD AND MAY DROP
ENTIRELY ONCE DVN/ILX 00Z RAOBS ARRIVE. THUS ITS MORE LIKELY CDFNT
COMES THROUGH DRY LTR TONIGHT.
VFR CONDS XPCD THROUGH THE PD AS OUTFLW BUBBLE HOLDS. SOME LOW END
POTENTIAL FOR MVFR VSBYS TO DVLP AFT 06Z AHD OF SFC BNDRY BUT GIVEN
THE DEGREE OF SFC BASED STABILIZATION THAT OCCURRED TDA AND AT LEAST
A LIGHT SW/W GRADIENT FLW SCRAPPED THAT W/00Z ISSUANCE.
&&
.SHORT TERM...
TONIGHT THROUGH THURSDAY NIGHT.
SHORT/SMALL WINDOW OF OPPORTUNITY WRT DESTABILIZATION INADV SFC
FNTL BNDRY ACRS XTRM SERN WI/NRN IL/ERN IA/MO LATE THIS AFTN. OF
NOTE HAS BEEN SPC RAP FAILURE TO ADEQUATELY ASSESS DOWNSTREAM
STABILIZATION AMID WAKE OF MATURE BUBBLE MESOHIGH BEHIND LATE
AM/ERLY AFTN LINEAR CONVECTION THAT NOW ARCHES FM NRN OH TO OH RVR
VALLEY. WHILE EWD ADVANCE OF STEEP 7-5H LAPSE RATES OF 8-9 C/KM
OMINOUS...THE CERTAINLY FAR FROM PRISTINE 0-3KM THERMODYNAMIC
ENVIRON ACRS NERN IL/CWA AMID DENSE CONVECTIVE DEBRIS AND WELL
OVERTURNED ATMOS...WL LKLY QUELL ALL BUT JUST A FLEETING HOPE FOR
ANY FIRM CONVECTIVE MAINTENANCE WITH ERN EXTENT. GIVEN
CONDITIONALITY WRT LATE AFTN INITIATION WITH MODEST LLVL WIND
PROFILE/LWST 100 MB CONVERGENCE AHEAD OF FNT...AND ADDED
CONDITIONALITY FURTHER DOWNSTREAM...HAVE CHOSE LOWER END GUID WITH
NO HIER THAN MID RANGE CHC POPS AFT 02 UTC. SEVERE RISK ALSO
APPEARS TO BE WANING...BUT WL LET HWO CONTINUE TO COVER WITH HIEST
RISKS ACRS SRN CWA/ALONG PROGGED OVERLAP OF SFC CAPE RESERVOIR
AND MODERATE DEEP LYR SHEAR/INCRSG THIS EVE AS 50 KT 5H WNWLY FLOW
ACRS IL/WI SURGES EWD. NIL WX AFTER TONIGHT IN DRYING LLVL ATMOS.
HAVE LWRD TEMPS INVOF KBEH SUBSTANTIALLY TMWR NIGHT IN WEAKENING
SFC FLOW AS 1018 MB PLAINS HIGH SETTLES ACRS SRN GRTLKS...FAVORING
COOL DRAINAGE ALONG LAKESHORE NEAR DAYBREAK FRI.
&&
.LONG TERM...
FRIDAY THROUGH WEDNESDAY...A SIGNIFICANT TROF WILL MOVE ACROSS THE
WESTERN GREAT LAKES REGION EARLY IN THE PERIOD. BOTH THE GFS AND THE
ECMWF HAVE ABANDONED THE EARLY CUT OFF LOW SOLUTION FROM MANY
PREVIOUS RUNS IN LIEU OF A MORE PROGRESSIVE OPEN WAVE SOLUTION DUE
TO MORE PHASING WITH THE NORTHERN STREAM AND THE APPROACH OF ANOTHER
UPSTREAM UPPER TROF. HOWEVER...THE ONGOING TIMING OF THE ARRIVAL OF
THE MAIN TROF OVER THE WESTERN GREAT LAKES REGION STILL APPEARS ON
TRACK WITH THE BEST CHANCE FOR RAIN FRIDAY NIGHT. KEPT SHOWERS
LIKELY FRIDAY NIGHT. ADDED A CHANCE FOR THUNDER SOUTHEAST HALF PER
ECMWF WITH EMBEDDED STORMS POSSIBLE GIVEN MOISTURE AND LIFT
AVAILABLE. OTHERWISE...COOLER AND DRY CONDITIONS SUNDAY AND MONDAY
FOLLOWED BY A RETURN TO ABOVE NORMAL TEMPERATURES WEDNESDAY AND THE
UPPER LEVEL RIDGE BUILDS EAST AHEAD OF THE NEXT UPPER LEVEL TROF CAN
BE EXPECTED. THE 500 MB CANADIAN AND GFS ANALOGS ALSO SUPPORT
TEMPERATURES RISING ABOVE NORMAL.
&&
.AVIATION... /18 UTC TAF/
UPSTREAM DESTABILIZATION RATHER SLOW TO RECOMMENCE HAS PLACED ADDED
CONDITIONALITY UPON CONVECTION ASSOCD WITH PRIMARY FRONTAL BOUNDARY
XTNDG FM SCNTL WI SEWD THROUGH IA TO NWRN MO LATER THIS AFTN. TIMING
WOULD PLACE THIS INTO NWRN IN AFTER SUNSET. ADDED UNCERTAINTY WRT
UNFAVORABLE CONVECTION MAINTENANCE WITH DOWNSTREAM EXTENT WITH SFC
STABILIZATION INCRSG AND MEAGER LLVL WIND FIELD. FOR NOW HAVE
COVERED GRTST POTNL TIMEFRAME WITH 4 HOUR VCTS GROUPINGS AS GRTR
CONFIDENCE FOR TEMPO LACKING ATTM.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...MURPHY
LONG TERM...SKIPPER
UPDATE/AVIATION...T
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
339 PM EDT TUE SEP 4 2012
.SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT.
SEVERAL CONCERNS TO DEAL WITH OVER THE NEXT 36 HOURS FROM
CONVECTION/SVR WX TO FOG.
WEAK FRONTAL BOUNDARY WAS ROUGHLY LOCATED FROM MONTICELLO TO FORT
WAYNE TO DEFIANCE WITH ISOL TO SCT SHOWERS STRUGGLING TO TAKE SHAPE
ALONG WITH GIVEN WEAK CONVERGENCE AND LIMITED INSTABILITY. WILL KEEP
A PRE 1ST PERIOD TO ADDRESS THIS ACTIVITY WHICH SHOULD EXIT BY 00Z.
WITH MOIST BOUNDARY LAYER AND LITTLE CHANCE FOR MIXING ACROSS THE
AREA TODAY...FOG/STRATUS POTENTIAL WILL REMAIN HIGH ACROSS MOST IF
NOT ALL OF THE FORECAST AREA. COULD SEE WIDESPREAD DENSE FOG LATER
TONIGHT IN MANY SPOTS WITH TEMPS FALLING PASS CROSSOVER TEMPS IN THE
UPPER 60S TO AROUND 70 AND CALM WINDS/CLEAR SKIES. POTENTIAL ISSUES
ARISE FROM ANTICIPATED UPSTREAM CONVECTION ACROSS MINN/WI/IOWA.
SEVERAL RUNS OF THE HRRR HAVE SHOWN DEVELOPMENT ACROSS THIS AREA
DROPPING TOWARDS POSSIBLE WESTERN PARTS OF THE FORECAST AREA LATER
TONIGHT/WEDS MORNING...POSSIBLY CAUSING ISSUES WITH FOG DEVELOPMENT.
FOR NOW...HAVE BUMPED UP WORDING IN ZONES TO PATCHY DENSE FOG AND
WILL DEFER TO EVENING/OVERNIGHT SHIFTS TO ADJUST BASED ON UPSTREAM
TRENDS.
STRONGER UPPER LEVEL TROUGH AND SFC COLD FRONT STILL POISED TO MOVE
INTO THE REGION WEDS/WEDS NGT. STRONG DYNAMICS WILL ACCOMPANY THE
SYSTEM WITH A FAVORABLE TIMING OF LIFT AND MSTR CONVERGENCE IN THE
LATE AFTERNOON/EARLY EVENING. GIVEN 0-6 KM SHEAR IN THE 30 TO 40 KT
RANGE SVR THREAT IS STILL POSSIBLE...IF SUFFICIENT HEATING CAN OCCUR
AHEAD OF THE ACTUAL FRONT. THE FLY IN THE OINTMENT FOR THIS MAY BE
ANY LATE NIGHT/MORNING CONVECTION NOTED ABOVE THAT COULD STABILIZE
THE AREA THROUGH OPTIMAL PEAK HEATING...THEREBY REDUCING CHANCES FOR
SVR WX. DO STILL FEEL THAT CONVECTION WILL FIRE TO THE WEST ALONG
THE FRONT IN ILLINOIS DURING THE AFTERNOON AND MOVE EAST TOWARDS THE
AREA. HAVE THEREFORE CAUTIOUSLY HELD WITH LIKELY POPS IN NW AREAS
WEDS AFTERNOON BUT FOR NOW BACKED OFF ON POP TIMING EARLIER IN THE
DAY ASSUMING THAT MODEL INDICATIONS OF IA/WI/MN COMPLEX DYING AS IT
APPROACHES OCCUR. THIS SAME REASONING WARRANTS A SLIGHT INCREASE IN
POPS WEDS NGT WITH POTENTIAL FOR SOMEWHAT SLOWER DEPARTURE OF
PRECIP...BUT NOT A RAMP UP TO LIKELY IN EASTERN AREAS GIVEN LESS
FAVORABLE TIME FRAME FOR CONVECTION TO MAINTAIN ITSELF UNLESS
ALREADY WELL ESTABLISHED.
&&
.LONG TERM...
THURSDAY THROUGH TUESDAY...THE MAIN CHALLENGES THIS PERIOD CONCERN
THE CHANCES FOR THE DEVELOPMENT OF A CUT OFF LOW OVER THE OHIO
VALLEY REGION THIS WEEKEND. ADDITIONAL CHALLENGES INCLUDE THE TIMING
AND EXTENT OF PRECIPITATION AND THE EFFECT ON TEMPERATURES IF THE
LOW DEVELOPS AND LINGERS OVER OR NEAR THE REGION. FOR THIS
PACKAGE...FAVOR THE ECMWF...ALTHOUGH THE 12Z RUN WAS AN OUTLIER
COMPARED TO THE PAST SEVERAL RUNS. THE 12Z ECMWF RUN WAS NOT USED
FOR THIS PACKAGE. THE PAST SEVERAL ECMWF RUNS HAVE HAD REASONABLE
RUN TO RUN CONSISTENCY. AS A WHOLE THE NEW 12Z GFS SOLUTION HAS
TRENDED TOWARD THE SLOWER...FARTHER WEST 00Z ECMWF SOLUTION.
ALSO...THE 00Z ECMWF HAS HAD BETTER SUPPORT WITH THE SURFACE
LOW/SURFACE REFLECTION CLOSER TO THE UPPER LOW THAN THE GFS. HAVE
RAISED RAIN CHANCES FRIDAY NIGHT GIVEN REASONABLE CONFIDENCE IN THE
TIMING OF THE SHORT WAVE TROF AND ASSOCIATED COLD FRONT. FOR THE
REST OF THE PERIOD...WENT WITH PERSISTENCE AND ATTEMPTED TO HOLD TO
THE PREVIOUS FORECAST WITH DRY CONDITIONS STARTING SUNDAY NIGHT.
&&
.AVIATION...
MVFR CIGS WERE MOVING BACK INTO BOTH SITES...AT KSBN IN THE WAKE
OF THE FRONT WITH STRATUS DECK FORMING...AND AT KFWA ALONG AN
ADVANCING FRONTAL BOUNDARY. CONTINUED WITH VCTS AT KFWA FOR A FEW
HORUS BUT SHORTLY AFTER ISSUING CONVECTION BEGAN TO FIRE JUST TO
SE OF AIRPORT. MAY AMEND TO REMOVE SOONER THAN 20Z BUT WILL
MONITOR FOR NOW.
OTHERWISE...MAIN FOCUS WILL BE LOW CLOUDS/FOG POTENTIAL OVERNIGHT
AT BOTH SITES. STRATUS DECK CURRENTLY AFFECTING KSBN COULD CAUSE
ISSUES WITH FOG DEVELOPMENT TONIGHT IF IT WE TO REMAIN AROUND.
HOWEVER...THIS SHOULD SCOUR OUT DURING THE AFTERNOON HOURS.
CIGS/VSBY TANKED RATHER RAPIDLY AT KFWA LAST NIGHT WITH DROP TO
NEAR 0SM VSBY RIGHT AROUND 12Z. SIMILAR CONDITIONS ARE POSSIBLE
TONIGHT AT BOTH SITES WITH EMPHASIS ON KFWA. HAVE INTRODUCED FOG
AND EVENTUAL IFR/LIFR CONDITIONS AT BOTH SITES LATER TONIGHT. FOG
SHOULD BURN OFF BY MID MORNING ONCE AGAIN. REMNANTS OF CONVECTION
THAT IS EXPECTED TO DEVELOP TO THE NW OF THE AREA TONIGHT MAY SNEAK
INTO KSBN IN THE 15 TO 18Z WINDOW. FOR NOW NO MENTION OF PRECIP.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...FISHER
LONG TERM...SKIPPER
AVIATION...FISHER
AREA FORECAST DISCUSSION
NWS DES MOINES IA
345 PM CDT TUE SEP 4 2012
.SHORT TERM /TONIGHT/...
PRIMARY CONCERN TONIGHT WILL BE CONVECTIVE TRENDS BUT CONFIDENCE IN
THAT EVOLUTION IS DECREASING AS MOST MODELS...HIGH RES EXPLICIT AND
PARAMETERIZED...ARE CURRENTLY OVERZEALOUS IN THEIR DEPICTION OF
PRECIP. PRESENT SITUATION HAS 80KT JET FROM ROCKIES INTO IA
ENHANCING DEEP/EFFECTIVE SHEAR. LITTLE IN THE WAY OF LARGE SCALE
FORCING NOTED IMMEDIATELY UPSTREAM HOWEVER WITH RAP ANALYSIS AND
WATER VAPOR IMAGERY FAIRLY BENIGN. ONLY SIGN OF LARGER SCALE UPWARD
VERTICAL MOTION /UVM/ SEEMS TO BE ACROSS CENTRAL NE NEAR H85/H7
SHORT WAVE PER VISIBLE IMAGERY. OUR FORECAST AREA SEEMS PRIMED FOR
DEVELOPMENT THERMODYNAMICALLY WITH UNCAPPED 2000-4000 J/KG MLCAPES.
HOWEVER SPOTTY CONVERGENCE AND LITTLE TO NO UVM OVERHEAD HAVE
RESULTED IN NO DEVELOPMENT AS OF YET. SMALL CELL ALONG HIGHWAY 20
DISSIPATED WHICH IS A SIGNAL THAT WE ARE NOT READY TO GO SURFACE
BASED AND/OR HAVE INSUFFICIENT UPPER LEVEL SUPPORT.
AT THE MOMENT FEEL THAT CONVECTIVE INITIATION IS GOING TO WAIT FOR
AFOREMENTIONED NE UVM ALONG WITH INCREASED SYNOPTIC SCALE FORCING
AHEAD OF MT/DAKOTAS SHORT WAVE AS IT MOVES EAST THIS EVENING.
ECMWF/GFS QG FORCING INCREASES AS IT REACHES MN BY 06Z. 18Z RAP
SUGGESTS WEAKLY CAPPED ELEVATED CAPES 2000 J/KG OR MORE WILL BE IN
PLACE AND CERTAINLY CAPABLE OF SUPPORTING SEVERE WEATHER CONSIDERING
OUR PROXIMITY TO THE JET. DCAPES SHOULD REMAIN QUITE HIGH
OVERNIGHT WITH SOUNDINGS SHOWING PLENTY OF DRY AIR BELOW 3KM. THUS
EXPECT NE CONVECTION TO SLOWLY DEVELOP AND MATURE AS IT REACHES IA
MUCAPE AXIS WITH DAMAGING WINDS AND HAIL QUITE POSSIBLE.
.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
FORECAST CONCERNS FOR WEDNESDAY WILL DEAL WITH A STRONG COLD FRONT
PUSHING ACROSS THE FORECAST AREA DURING THE MORNING AIDED BY A
POTENT SHORT WAVE SWEEPING ACROSS THE NORTHERN PLAINS INTO IA. MOST
OF THE CAPE AND SHEAR ARE AHEAD OF THE BOUNDARY SO ONGOING
CONVECTION FROM THE OVERNIGHT WILL AFFECT THE EASTERN HALF OR SO OF
THE FORECAST AREA. BEHIND THE FRONT MUCH COOLER AND DRIER AIR WILL
PUSH INTO CENTRAL IOWA DURING THE AFTERNOON SO ANY THUNDERSTORM
THREAT IN THE AFTERNOON WILL BE CONFINED TO THE FAR SOUTHEAST
PORTION OF CENTRAL IOWA ON EAST. BEYOND WEDNESDAY WE BEGIN OUR
SLIDE IN TEMPS AS HIGH PRESSURE BUILDS IN WEDNESDAY NIGHT THROUGH
LATE THURSDAY. WARM ADVECTION OCCURS THURSDAY NIGHT AHEAD OF THE
NEXT SYSTEM TO AFFECT THE AREA. ON FRIDAY THETA ADVECTION INCREASES
AND A SECOND SHORT WAVE ROTATES THROUGH THE NORTHERN AND CENTRAL
PLAINS BRINGING AND ANOTHER FRONT WILL PUSH ACROSS IOWA BRINGING A
REINFORCING SHOT OF COLD AIR. SHOWERS AND ISOLATED THUNDERSTORMS
WILL OCCUR WITH THIS FOLLOWED BY SOME VERY COOL AIR. TEMPERATURES
OVER THE WEEKEND WILL ACTUALLY BE BELOW NORMAL BUT IT WILL BE DRY.
&&
.AVIATION...04/12Z
VFR CONDITIONS ARE NOTED THROUGH THE PERIOD...BUT THAT IS MORE DUE
TO A LACK OF CONFIDENCE IN TIMING THAN OCCURRENCE. MODELS SUGGEST
CONVECTION WILL DEVELOP LATER THIS AFTERNOON OR THIS EVENING...BUT
DECIDED TO JUST MENTION VFR VCSH WORDING FOR NOW RATHER THAN TRY TO
TAKE A STAB AT A DIFFICULT TO PREDICT CONVECTIVE WINDOW. CHANCES
FOR CONVECTION DIMINISH OVERNIGHT AND THERE MAY BE A PERIOD OF
REDUCED VSBYS IN FOG...BUT AGAIN PREDICTABILITY IN THIS REGARD IS
LOW DUE TO CONVECTIVE TRENDS SO IT IS OMITTED FOR NOW. FRONT WILL
PASS THROUGH SITES WED MORNING ENDING PRECIP AND FOG THREAT.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/AVIATION...SMALL
LONG TERM...FAB
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1119 PM MDT MON SEP 3 2012
.UPDATE...
ISSUED AT 841 PM MDT MON SEP 3 2012
JUST COMPLETED AN UPDATE. PRECIPITATION FORECAST APPEARS TO BE ON
TRACK. EARLIER PRECIPITATION HAS DECREASED OR ENDED. HOWEVER...ENTRANCE
REGION OF UPPER JET REMAINS IN THE AREA THROUGH THE NIGHT AS ANOTHER
SHORTWAVE TROUGH MOVES THROUGH. ALSO SOME SURFACE CONVERGENCE AROUND
MAINLY IN THE NORTHWEST. CURRENT ANALYSIS HAS INCREASING ELEVATED
CINH AND DECREASING ELEVATED CAPE. NAM SHOWS NO INSTABILITY DURING
THE NIGHT WITH GFS MAINTAINING A DECENT AMOUNT OF ELEVATED CAPE
WITH NOT A LOT OF CINH.
MODELS INSISTING ON KEEPING OR REDEVELOPING PRECIPITATION OVER THE
SOUTHERN PORTION OF THE AREA THROUGH THE NIGHT. AFTER SAYING ALL
THAT CURRENT GRIDS DO HAVE THIS DEPICTION AND FEEL COMFORTABLE IN
KEEPING THIS FORECAST AT THIS TIME. WEST WINDS AND LOWER DEWPOINTS
LOOK TO SPREAD FROM WEST TO EAST ACROSS THE AREA THROUGH THE NIGHT
WITH THE THICKEST CLOUD COVER OVER THE SOUTH. AS A RESULT LOWERED
DEWPOINTS OVER THE ENTIRE AREA AND LOWERED MINS OVER THE NORTHERN
HALF TO TWO THIRDS.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 200 PM MDT MON SEP 3 2012
LATEST WV IMAGERY SHOWS A NARROW BAND OF SUBSIDENCE OVER EASTERN
COLORADO MOVING INTO THE TRI-STATE AREA BEHIND THE UPPER LEVEL
TROUGH THAT BROUGHT LIGHT RAINFALL TODAY. RUC ANALYSIS HAS A SECOND
SHORT WAVE TROUGH FOLLOWING THE SUBSIDENCE BEHIND THE INITIAL SHORT
WAVE. AT THE SURFACE THE COLD FRONT FROM YESTERDAY EXTENDS FROM
SOUTHWEST KANSAS NORTHEAST TO IOWA. ANY STORM ACTIVITY THAT DEVELOPS
ALONG THE FRONT SHOULD BE WELL SOUTH OF THE AREA. OTHERWISE A
SUBTLE SURFACE TROUGH WAS LOCATED BETWEEN WRAY AND SAINT
FRANCIS...WHICH MAY SERVE TO HELP FOCUS CONVECTION OVER THE
NORTHWEST LATE THIS AFTERNOON AND THIS EVENING.
EARLY THIS EVENING SURFACE CONVERGENCE WILL DEVELOP OVER THE
NORTHWEST PART OF THE AREA BELOW A 700-500MB SHORT WAVE TROUGH.
THE DEEP LIFTING WILL GIVE THE BEST SHOT FOR RAINFALL TO REACH THE
GROUND. MEANWHILE THERE MAY BE SOME LINGERING STORMS IN THE HILL
CITY TO MCCOOK AREA...AS THE 700-500MB SHORT WAVE TROUGH THAT
BROUGHT RAIN EARLIER TODAY DEPARTS THE AREA. AS THE NIGHT
PROGRESSES PRECIP. CHANCES SHIFT FROM THE NORTHWEST TO THE SOUTH
AS A ANOTHER SHORT WAVE TROUGH MOVES ACROSS THE AREA. WITH A DEEP
DRY LAYER IN PLACE...AM NOT TOO CONFIDENT ANYTHING WILL REACH THE
GROUND.
TUESDAY ANOTHER SHORT WAVE TROUGH WILL MOVE THROUGH THE AREA.
DURING THE LATE MORNING THROUGH THE AFTERNOON A PRE-FRONTAL TROUGH
WILL DEVELOP AT THE SURFACE BELOW THE SHORT WAVE TROUGH. LIFT ALONG
THE SURFACE AND MID LEVEL TROUGH INCREASE THROUGH THE DAY. WITH
STRONGER LIFT OCCURRING DURING THE AFTERNOON HAVE INCREASED PRECIP.
CHANCES ALONG AND EAST OF THE SURFACE TROUGH. THESE AREAS WILL BE MORE
LIKELY TO HAVE STRONG TO SEVERE THUNDERSTORMS DUE TO THE BETTER
INSTABILITY.
THE 0-6KM SHEAR WILL BE AROUND 30 TO 35 KTS FOR THE PERIOD...WHICH
WILL SUPPORT ORGANIZED STORM STRUCTURE WITH PROLONGED UPDRAFTS. AM
THINKING THE MAIN THREAT WITH THESE STORMS WILL BE STRONG TO SEVERE
WIND GUSTS DUE TO THE HIGH CLOUD BASES.
TEMPERATURES WILL BE SIMILAR TO LAST NIGHT AND TODAY...WITH LOWS IN
UPPER 50S TO LOW 60S AND HIGHS IN THE 90S.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 131 PM MDT MON SEP 3 2012
TUESDAY NIGHT-THURSDAY...WILL KEEP A SMALL CHANCE OF PRECIPITATION
IN THE FORECAST EARLY TUESDAY NIGHT BEFORE DRIER AIR WORKS INTO
THE AREA UNDER NORTHWEST FLOW ALOFT THROUGH EARLY THURSDAY
MORNING. NOT TERRIBLY EXCITED ABOUT PRECIPITATION CHANCES THURSDAY
AFTERNOON DESPITE MOISTURE AVAILABILITY AS DYNAMICS RATHER WEAK.
TRIMMED POPS DOWN JUST A BIT. HIGH TEMPERATURES WEDNESDAY IN THE
LOW TO MID 80S...WARMING INTO THE UPPER 80S TO LOW 90S THURSDAY.
LOWS IN THE 50S TO LOW 60S.
THURSDAY NIGHT-FRIDAY NIGHT...PRECIPITATION CHANCES WILL SLOWLY
INCREASE THROUGH FRIDAY AS AN UPPER TROUGH AND COLD FRONT
APPROACH THEN MOVE THROUGH THE AREA. PRECIP CHANCES DECREASE FROM
NORTH TO SOUTH FRIDAY NIGHT AS THE SYSTEM MOVES OUT OF THE AREA
AND STABLE HIGH PRESSURE MOVES IN. HIGH TEMPERATURES FRIDAY 75-80.
LOWS THURSDAY NIGHT IN THE LOW 60S COOLING INTO THE LOW TO MID
50S FRIDAY NIGHT BEHIND THE FRONT.
SATURDAY-MONDAY...DRY. HIGH TEMPERATURES SATURDAY IN THE MID TO
UPPER 70S...WARMING INTO THE MID 80S TO AROUND 90 BY MONDAY.
OVERNIGHT LOWS NEAR TO SLIGHTLY ABOVE NORMAL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1115 PM MDT MON SEP 3 2012
MODELS HAVING DIFFICULTY DURING THIS TIME PERIOD. WITH NUMEROUS
SHORTWAVE TROUGHS MOVING THROUGH MODELS ARE ALL OVER THE PLACE
WITH THE WIND FIELD AND PLACEMENT OF PRECIPITATION. AT THIS TIME
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. CURRENT
THUNDERSTORM ACTIVITY SHOULD STAY SOUTH OF KGLD THROUGH THE NIGHT.
TOMORROW...DEPENDING ON POSITION OF PREFRONTAL TROUGH...HIGH BASED
THUNDERSTORMS COULD AFFECT EITHER SITE BEGINNING IN THE MID TO
LATE AFTERNOON HOURS. AS A RESULT OF THE UNCERTAINTY AND
PRECIPITATION CHANCES NOT OCCURRING UNTIL THE QUARTER TO HALF OF
THE PERIOD...CHOSE TO HANDLE THE CHANCES WITH VCTS. FURTHER
REFINEMENTS OF THE WIND FIELD AND THUNDERSTORM CHANCE WILL
CONTINUE TO BE NEEDED.
&&
.FIRE WEATHER...
ISSUED AT 200 PM MDT MON SEP 3 2012
TUESDAY AFTERNOON AREAS NORTH OF A KIT CARSON TO MCCOOK LINE WILL
HAVE RELATIVE HUMIDITIES DROP TO AROUND 15 PERCENT DURING THE
AFTERNOON. IN ADDITION WIND GUSTS AROUND 20 MPH CAN BE EXPECTED.
WHILE THIS IS BELOW ISSUANCE CRITERIA...CARE SHOULD BE TAKEN FOR
ANY OUTDOOR BURNING.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...BULLER
SHORT TERM...JTL
LONG TERM...99
AVIATION...BULLER
FIRE WEATHER...JTL
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
1111 AM CDT TUE SEP 4 2012
.DISCUSSION...
SO FAR JUST ABOUT A REPEAT PERFORMANCE OF YESTERDAY/S EFFORT WITH
SIMILAR READINGS AT THIS TIME. PARTLY CLOUDY CONDITIONS ARE NOTED
ON SATELLITE IMAGERY OVER DEEP EAST TEXAS WITH LITTLE IF ANY CLOUDS
ELSEWHERE OVER THE FOUR STATE AREA. WATER VAPOR SHOWS THE RIDGE
OVERHEAD. ALREADY MANY READINGS AT 90 DEGREES WITH A BIT LESS
WIND THAN YESTERDAY SO LIKEWISE MIXING MAY DELAY INTO THE MID
AFTERNOON TODAY. THE ONLY CHANGE OF NOTE IS IN THE RAP MODEL WHICH
SHOWS SOME TENTHS OF QPF ALONG AND SOUTH OF I-20 OVER NORTH
CENTRAL LOUISIANA. PERHAPS ATTENDANT TO THE MCV OVER AL THIS
MORNING. SFC WINDS ARE COMING AROUND OVER NORTHERN MS TO THE NE
AND ANY SORT OF BOUNDARY THAT MAY RESULT WOULD HAVE A CHANCE IN
THE MOIST DELTA REGION FOR FURTHER INITIATION OF CONVECTION. THE
CURRENT FORECAST HAS NO WORDING FOR SUCH...BUT OUT OF RESPECT FOR
THIS MODELS PERFORMANCE OVER THE LAST COUPLE MONTHS HAVE INCREASED
POP HERE WITH NO MENTION OF WEATHER AT THIS TIME. NEXT TEXT
PRODUCTS SENT WITH ONLY SLIGHT CHANCES TO A FEW ZONES FOR SKY.
ALSO WE HAVE BLENDED LAPS WITH SOME NEW NAM WIND DATA. /24/
&&
.AVIATION...
SIMILAR SCENARIO THIS MORNING...AS VFR FLIGHT CATEGORIES WILL REMAIN
COMMON ACROSS THE AREA TODAY. SKC WILL BE POPULAR IN MANY AREA
METARS. HOWEVER SOME MVFR CIGS STILL LINGER IN DEEP EAST TEXAS AS
SEEN BY KLFK...BUT THESE CLOUDS ARE SCATTERING OUT QUICKLY.
SOUTHWEST WINDS OF 10 TO 15 KTS WILL BE OBSERVED THIS
AFTERNOON...THEN DIMINISH TO 5 TO 10 KTS WITH SUNSET. NO VSBY
CONCERNS ARE EXPECTED IN THE 18Z TAF PERIOD. /11/
&&
.PREV DISCUSSION... /ISSUED 408 AM CDT TUE SEP 4 2012/
DISCUSSION...
WV IMAGERY THIS MORNING CONTINUES TO SHOW UPPER RIDGING OVER OUR
REGION...WITH A TROF OVER THE SERN U.S. AND ANOTHER TROF SWEEPING
OVER THE TOP OF THE RIDGE ACROSS THE NRN PLAINS. THE INFLUENCE OF
THE UPPER RIDGE WILL MAKE FOR ANOTHER HOT DAY ACROSS THE REGION.
HAVE GONE WITH ANOTHER HEAT ADVISORY ACROSS EXTREME NE TX...SE
OK...SW AR...NW AND N CENTRAL LA WHERE EITHER 100+ TEMPS OR 72+
DEWPOINTS WILL FORCE HEAT INDICES TO EXCEED 105 DEGREES. A FEW
OTHER LOCATIONS ACROSS E TX MAY BRIEFLY SEE 105 DEGREE HEAT
INDICES...BUT THESE OCCURRENCES SHOULD REMAIN TOO ISOLATED TO
WARRANT BEING INCLUDED IN THE HEAT ADVISORY. AT ANY RATE...THE
HEAT IS EXPECTED TO CONTINUE THROUGH THU...BEFORE THE RIDGE
BEGINS TO BREAK DOWN. UPPER TROF MOVING INTO THE NRN PLAINS WILL
FORCE THE RIDGE SWD AND BRING SOME RAIN CHANCES TO THE NRN
PORTIONS OF THE REGION THU...BEFORE ANOTHER TROF DIGS SEWD FRI AND
FORCES THE RIDGE TO RETREAT WELL TO THE W. RAIN CHANCES WILL BE ON
THE INCREASE FOR THE WEEKEND...AS THIS FALL-LIKE UPPER TROF/COLD
FRONT MOVE ACROSS THE WRN GULF STATES. SIGNIFICANTLY COOLER AND
DRIER AIR IS FCST TO FOLLOW AS SFC HIGH PRESSURE BUILDS IN BEHIND
THE FRONT...WITH TEMPS EXPECTED TO DIP SEVERAL DEGREES BELOW
NORMAL FOR THE EARLY PART OF NEXT WORK WEEK. /12/
AVIATION...
MOSTLY VFR FLIGHT WEATHER TODAY. PATCHY CIGS BETWEEN 7 HUNDRED
AND 15 HUNDRED FEET THIS MORNING ACROSS DEEP EAST TEXAS INTO
NORTHCENTRAL LOUISIANA...SOUTH OF INTERSTATE 20...WILL GIVE WAY TO
MOSTLY CLEAR SKIES BY 15Z. SURFACE WIND SOUTH TO SOUTHWEST 5 TO 10
KTS EARLY THIS MORNING BECOMING WEST TO SOUTHWEST 8 TO 12 KTS AFTER
16Z. /14/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 99 76 100 75 99 / 10 10 10 10 10
MLU 100 76 99 72 97 / 10 10 10 10 20
DEQ 103 71 103 72 99 / 10 10 10 20 20
TXK 100 76 100 75 98 / 10 10 10 10 10
ELD 98 73 99 72 98 / 10 10 10 10 20
TYR 98 77 99 75 98 / 10 10 10 10 10
GGG 98 76 100 73 99 / 10 10 10 10 10
LFK 98 74 99 73 98 / 10 10 10 10 10
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING
ZONES: ARZ050-051-059>061-070>073.
LA...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING
ZONES: LAZ001>006-010>014-017>022.
OK...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING
ZONES: OKZ077.
TX...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING
ZONES: TXZ096-097.
&&
$$
24/11
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
128 PM EDT TUE SEP 4 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 438 AM EDT TUE SEP 4 2012
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW FAST ZONAL FLOW
OVER THE NRN TIER CONUS TO THE S OF DEEP OCCLUDED LO CENTERED OVER
NRN MANITOBA. DISTURBANCE/AREA OF DEEPER MSTR RESPONSIBLE FOR
SHRA/TS YDAY HAS PUSHED TO THE E AND GIVEN WAY TO WEAK HI PRES AND
DRIER AIR. SOME AREAS OF DENSE FOG HAVE DVLPD OVER MAINLY THE ERN
AND CNTRL CWA WITH LGT WINDS WHERE THE DRYING ALF HAS OUTRUN THE
NEAR SFC DRYING. FOG APPEARS LESS PREVALENT OVER THE W WHERE DRIER
LLVL AIR APRNT ON THE 00Z INL/MPX RAOBS HAS MADE GREATER INROADS.
DESPITE THE PRESENCE OF THIS DRY AIR...SOME SHRA/A FEW TS ARE NOTED
OVER NW MN NEAR AN INCOMING SHRTWV/SFC LO PRES TROF IN AREA WHERE
NAM/GFS SHOW SOME H85 THETA E ADVECTION. SOME PATCHY MID/HI CLDS
AHEAD OF THIS DISTURBANCE ARE DRIFING INTO THE WRN CWA. FARTHER TO
THE NW...ANOTHER STRONGER SHRTWV IS OVER SASKATCHEWAN AND MOVING
SEWD ON THE SRN FLANK OF CLOSED LO IN MANITOBA.
EARLY THIS MORNING...OPTED TO ISSUE AN SPS FOR MUCH OF THE E AND
CNTRL CWA TO HIGHLIGHT LOCALLY DENSE FOG.
TODAY...EXPECT FOG TO BURN OFF THIS MRNG WITH ONSET OF DAYTIME
HEATING. CONCERN THEN TURNS TO IMPACT OF SHRTWV NOW MOVING E THRU
NRN MN. SEVERAL MODELS...ESPECIALLY THE 00Z NAM/CNDN...SHOW SOME
FAIRLY SHARP DEEP LYR QVECTOR CNVGC/H3-2 DVGC/AXIS OF HIER H85-5 RH
ASSOCIATED WITH DPVA/H85 THETA E ADVECTION IMPACTING THE WRN ZNS
THIS AFTN INTO THE EARLY EVNG. IN FACT...RECENT SPC CONVECTIVE
OUTLOOK HAS THE FAR W IN A SLIGHT RISK FOR SVR STORMS LATE THIS
AFTN/EARLY EVNG. MODIFIED GFS FCST SDNG FOR IWD LATE IN THE AFTN
YIELDS SBCAPE NEAR 1900 J/KG FOR SFC T/TD 84/60 UNDER STEEP MID LVL
LAPSE RATES. THE NAM INDICATES 2000-2500 J/KG MUCAPE IN THIS AREA. A
POSITIVE FOR SVR STORMS IS THE STEEP MID LVL LAPSE RATES/PRESENCE OF
DRY AIR IN THE MID LVLS WITH SFC-10K FT DELTA THETA E 15-20C AND
INVERTED V LOOK TO THE LLVL TEMP/DEWPT PROFILES THAT WOULD ENHANCE
THE THREAT OF GUSTY WINDS. ON THE OTHER HAND...GENERALY DRYNESS OF
THE ATMOSPHERE WL TEND TO LIMIT THE COVERAGE OF THE STORMS. ALSO
DEEP LYR SHEAR IS FCST TO BE UP TO 30 KTS...A BIT MARGINAL BUT
PROBABLY ENUF TO ALLOW FOR AT LEAST PULSE SVR STORMS. OTRW...EXPECT
ANOTHER WARM DAY WITH H85 TEMPS IN THE 16-18C RANGE SUPPORTING HI
TEMPS IN THE 80S AWAY FM LK BREEZES THAT WL TEND TO FORM OFF MAINLY
LK MI WITH SSE H925 FLOW.
TNGT...EXPECT BAND OF SCT SHRA/TS MOVING W-E INTO THE E HALF TO
SLOWLY DIMINISH WITH LOSS OF DAYTIME HEATING/SHIFT OF SUPPORTING
DEEP LYR QVECTOR CNVGC TO THE N INTO ONTARIO. WITH SOME DNVA/
NEGATIVE H85 THETA E ADVECTION/DEEP LYR QVECTOR DVGC FOLLOWING THIS
BAND... EXPECT A PERIOD OF DRY WX. HOWEVER...APRCH OF SHARPER SHRTWV
NOW MOVING SEWD THRU SASKATCHEWAN AND VIGOROUS DPVA/DEEP LYR QVECTOR
CNVGC/SOME UPR DVGC WILL BRING BACK A THREAT OF SHRA/TS OVER THE W
LATE. LIMITING FACTORS WILL BE LIMITED MSTR RETURN...SOME GUIDANCE
ACTUALLY SHOWS NEGATIVE H85 THETA E ADVECTION...AND ARRIVAL OF THE
DYNAMICS AT TIME OF MIN DIURNAL HEATING.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 438 AM EDT TUE SEP 4 2012
STARTING WITH WEDNESDAY...MOST OF THE GUIDANCE BRINGS A MODEST COLD
FRONT THROUGH UPPER MI LATE WEDNESDAY MORNING INTO THE AFTERNOON. AS
FOR MOISTURE AND INSTABILITY...850MB THETA E RIDGE SPRAWLS ITSELF
ACROSS THE CWA TUESDAY NIGHT. PLENTY OF MOIST AIR WILL BE IN PLACE
AS THE NOSE OF AN 850MB JET AIMS INTO SOUTHWESTERN UPPER MI...WITH
PWATS EXPECTED TO BE 130-150 PERCENT OF NORMAL. SFC BASED CAPE
DURING THE EARLY AFTERNOON IS AROUND 1000-1500 J/KG...AND MUCAPE IS
UPWARDS OF 1800 J/KG. HIGHEST VALUES ARE IN THE SOUTH-SOUTH CENTRAL
PORTIONS OF THE CWA. LOOKING AT FORECAST SOUNDINGS IT SEEMS WITH
SHORTWAVE MOVING THROUGH DURING PEAK HEATING WE SHOULD HAVE ENOUGH
GUSTO TO BREAK THE WEAK CAP THAT WILL BE IN PLACE. AS FAR AS ANY
SUPPORT GOES...300MB JET STREAK SLIDES ACROSS THE CWA IN THE
AFTERNOON...WITH RIGHT ENTRANCE REGION DYNAMICS IN PLAY ACROSS
MAINLY THE SOUTH CENTRAL PORTION OF THE CWA. ECMWF HAS 500MB VORT
MAXIMUM SLIDING INTO THE WEST HALF OF UPPER MI BY 18Z. WITH THE
300/850 MB JET STREAKS MOVING THROUGH 0-6 KM SHEAR IS AROUND 25-35
KNOTS. OVERALL THIS GIVES US A MODERATE CAPE/SHEAR ENVIRONMENT AND
POTENTIAL FOR A SEVERE LINE OF STORMS...LIKELY DEVELOPING ACROSS THE
SOUTHERN PORTIONS OF THE CWA WHERE LIFT AND INSTABILITY IS
MAXIMIZED.
THURSDAY WE DEAL WITH COOLER DRY AIR BEHIND THE FRONT/IN THE WAKE OF
THE LOW PRESSURE SYSTEM NEAR JAMES BAY. DRY AIR PUNCHES IN ALOFT
OVERNIGHT ON WEDNESDAY...SO IT LOOKS LIKE THURSDAY WILL BE
RELATIVELY QUIET IN TERMS OF PRECIPITATION. PWATS DROP DOWN TO NEAR
70 PERCENT OF NORMAL AT TIMES AS SURFACE HIGH PRESSURE MOVING ACROSS
THE MIDWEST TRIES TO RIDGE INTO UPPER MI. BY FRIDAY THE LOW BEGINS
TO OCCLUDE NEAR JAMES BAY...SWINGING AN UPPER LEVEL TROUGH ACROSS
UPPER MICHIGAN ONCE MORE. ECMWF GENERATES PRECIPITATION ACROSS
CENTRAL AND EASTERN PRECIPITATION FOR THE DAY ON FRIDAY...SUPPORTED
BY MODERATE 850-500MB QVECTOR CONVERGENCE AND LINGERING MOISTURE
/PWATS AROUND 110 PERCENT OF NORMAL/. WITH NORTHWEST FLOW AND
LAKE-850MB TEMP DIFFERENCES AROUND 15-18C...EXPECT A LAKE EFFECT
COMPONENT TO PRECIPITATION NEAR LAKE SUPERIOR. ADDITIONALLY...STRONG
ONSHORE FLOW WILL GENERATE WAVES AS HIGH AS 3 TO 5 FEET IN THE ALGER
AND EASTERN MARQUETTE COUNTY SURF ZONE FRIDAY INTO SATURDAY
MORNING...LEADING TO THE POSSIBILITY FOR RIP CURRENT DEVELOPMENT.
WITH THE COLD FRONT PASSING WEDNESDAY AFTERNOON/EVENING TEMPERATURES
WILL BE MORE FALL LIKE...WITH HIGHS IN THE 60S AND LOW 70S THROUGH
THE REMAINDER OF THE PERIOD. ALONG WITH FALL LIKE TEMPERATURES...WE
CAN EXPECT FALL-LIKE FEATURES. FRIDAY THERE IS AN ELEVATED POTENTIAL
FOR WATERSPOUT DEVELOPMENT AS COOLER TEMPERATURES ALOFT MOVE IN OVER
THE STILL WARM LAKE. FORECASTS PER THE INTERNATIONAL CENTRE FOR
WATERSPOUT RESEARCH ARE STILL INDICATING THAT CONDITIONS WILL BE
FAVORABLE FOR THEIR DEVELOPMENT.
AS THE SFC/500MB HIGH PRESSURE RIDGE OVER THE NORTHERN PLAINS BUILDS
INTO UPPER MICHIGAN FOR THE WEEKEND AND THROUGH THE FIRST PORTION OF
THE WORK WEEK...EXPECT CONDITIONS TO REMAIN FAIRLY DRY. THE ONLY
EXCEPTION IS THE LOW PRESSURE SYSTEM THAT DEVELOPS IN THE OHIO
VALLEY FRIDAY...LINGERING OVER LOWER MI THROUGH THE EXTENDED. THIS
COULD BRING SLIGHT CHANCE POPS OVER THE EASTERN U.P. FOR SATURDAY
INTO MONDAY. FOR NOW WITH MODEL DIFFERENCES IN LOCATION AND TIMING
OF THIS PRECIP WILL KEEP THE MODEL CONSENSUS IN FORECAST UNTIL THE
FINER DETAILS CAN BE NARROWED DOWN.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 128 PM EDT TUE SEP 4 2012
AN APRCHG LO PRES TROF WILL BRING THE THREAT OF SHRA/SOME TS TO
MAINLY IWD THIS AFTN/EVNG BEFORE THE TROF MOVES TO THE E THIS EVNG.
WITH LGT WINDS/DRYING ALF IN THE WAKE OF THE TROF...MORE FOG MAY
FORM OVERNGT. BUT THE APRCH OF ANOTHER LO PRES TROF SHOULD BRING
MORE CLDS/-SHRA TO IWD TOWARDS DAYBREAK AND TO CMX AND SAW DURING
THE MORNING WEDNESDAY. PRIOR TO THIS SAW WILL HAVE THE BEST CHANCE
OF EXPERIENCING IFR CONDITIONS IN FOG BEFORE SUNRISE.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 438 AM EDT TUE SEP 4 2012
EXPECT SSW WINDS TO INCREASE UP TO 20 KTS TODAY MAINLY OVER THE E
HALF IN ADVANCE OF AN APPROACHING LO PRES TROF. THESE STRONGER WINDS
WILL BRING DRIER AIR OVER THE E HALF OF THE LAKE AND DISSIPATE FOG
THAT DEVELOPED DURING THE NIGHT IN THE WAKE OF SHOWERS THAT FELL ON
MON. ALTHOUGH WINDS WILL DIMINISH FOR A TIME WITH THE PASSAGE OF THE
TROF...EXPECT W TO NW WINDS IN ITS WAKE LATE WED THRU THU TO
INCREASE UP TO 20 TO 25 KTS AS COOLER AIR ARRIVES OVER THE
RELATIVELY WARM LAKE WATERS AND ENHANCES MIXING. ALTHOUGH WINDS MAY
DIMINISH FOR A TIME ON THU NIGHT AS ANOTHER TROF SWINGS OVER LAKE
SUPERIOR...PLAN ON ANOTHER ROUND OF STRONGER NW WINDS UP TO 25 KTS
ON FRI IN ITS WAKE. THE APPROACH OF HIGH PRESSURE/A WEAKENING PRES
GRADIENT THIS WEEKEND WILL CAUSE WINDS TO SLOWLY DIMINISH.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...MCD
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
122 PM EDT TUE SEP 4 2012
.SYNOPSIS...
ISSUED AT 1125 AM EDT TUE SEP 4 2012
CLOUDS WILL DECREASE THIS AFTERNOON BEHIND SHOWERS AND
THUNDERSTORMS EXITING THE THE AREA. STRONG OR SEVERE THUNDERSTORMS
ASSOCIATED WITH A COLD FRONT ARE EXPECTED WEDNESDAY AFTERNOON AND
EVENING. BEHIND THE FRONT...SEASONABLY COOL TEMPERATURES AND SCATTERED
SHOWERS WILL FINISH THE WORK WEEK AND LAST INTO THE WEEKEND.
&&
.UPDATE...
ISSUED AT 1125 AM EDT TUE SEP 4 2012
UPDATED THE TIMING OF PRECIPITATION EXITING THE AREA. WE CONTINUE
TO ADVERTISE GRADUAL CLEARING THIS AFTERNOON WITH GREATLY REDUCED
PRECIPITATION CHANCES. WE HAVE MODERATE CONFIDENCE ABOUT THE
CLEARING AND SOMEWHAT BETTER CONFIDENCE ABOUT THE DECREASED
CHANCES FOR RAIN THIS AFTERNOON.
WE WILL HAVE TO WATCH FOR LINGERING CLOUDS THIS AFTERNOON...
PARTICULARLY OVER OUR NW ZONES. METARS AND VISIBLE SATELLITE
INDICATE A WEAK COLD FRONT SURGING SE FROM THE GREEN BAY AREA WITH
SIGNIFICANT CLOUDINESS BEHIND THIS FRONT. LATEST HRRR GUIDANCE
WASHES OUT THE FRONT THIS AFTERNOON WHEN A DIURNALLY FORCED LOW
PRESSURE AREA FORMS ACROSS LOWER MICHIGAN. THIS WOULD HELP TO
DECREASE CLOUD COVERAGE AREA-WIDE...BUT OF COURSE ALSO ASSUMES
LIMITED CLOUDINESS IN THE FIRST PLACE TO HELP THE DIURNAL FORCING.
CLOUD TRENDS OVER THE NEXT FEW HOURS WILL THEREFORE BE IMPORTANT.
UPDATE ISSUED AT 610 AM EDT TUE SEP 4 2012
I UPDATED THE GRIDS AND ZONE TO PUT CONDITIONAL POPS FOR THE NEXT
FEW HOURS AS THE BAND OR RAIN AND EMBEDDED THUNDERSTORMS ASSOCIATE
WITH THE MID LEVEL TROUGH CONTINUE TO MOVE EAST ACROSS THE CWA. I
ALSO SERIOUSLY INCREASED THE QPF SINCE I HAVE RECEIVED MESONET
REPORTS LIKE .67 INCHES IN JENISON. THE INDIANA TRAILS GOLF
COURSE JUST SOUTH OF THE CITY OF GRAND RAPIDS HAD 1.01 INCHES IN
15 MINUTES. IN ANY EVENT THIS AREA OF SHOWERS IS ASSOCIATED WITH
THE 700 MB TROUGH AND THERE IS STRONG SUBSIDENCE BEHIND IT. I
BELIEVE SKIES WILL CLEAR BEHIND THIS AND ADDITIONAL CONVECTION IS
UNLIKELY MID TO LATER AFTERNOON OVER OUR CWA SUE TO THE SUBSIDENCE
BEHIND THE SHORTWAVE.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 320 AM EDT TUE SEP 4 2012
FORECAST CONCERNS DEAL WITH CONVECTIVE TRENDS TODAY AND WEDNESDAY.
NOT MANY CHANGES WERE MADE TO THE GOING FORECAST.
MODEL TRENDS THE PAST 24 HRS HAVE SLOWED THE TIMING OF THE COLD
FRONT WEDNESDAY BY A FEW HOURS AND INSTEAD OF MOVING ACROSS THE
CWA DURING THE AFTERNOON...THE FRONT MAY MOVE THROUGH DURING THE
EVENING. DUE TO DIURNAL INSTABILITY FADE...THE SEVERE THREAT HAS
EFFECTIVELY SHIFTED A BIT WWD AND THE SERN CWA HAD BEEN REMOVED
FROM THE DAY2 OUTLOOK.
LATEST REGIONAL RADAR SHOWS A BROKEN LINE OF SHOWERS AND ISOLATED
STORMS STRETCHING FROM NE LWR TO NEAR CHICAGO. THIS PCPN IS
ASSOCIATED WITH A WEAKENING FRONTAL BOUNDARY AND WILL CROSS THE
CWA TODAY. MESO ANALYSIS SHOWS EFFECTIVE SHEAR NEAR 40KTS ALONG
THE I-96 CORRIDOR ATTM. INSTABILITY HOWEVER IS LOW AND SO SVR
STORMS ARE NOT EXPECTED. THERE IS A LOW LEVEL DEW POINT GRADIENT
THAT STRETCHES ALONG I-69/96 AND WE MAY SEE A FLAREUP OF
CONVECTION AS THE ONGOING PCPN INTERACTS WITH IT.
SKIES WILL BECOME PT/MO SUNNY BEHIND THE CONVECTION TODAY AND
TEMPS WILL ONCE AGAIN CLIMB INTO THE MID TO UPPER 80S.
A STRONGER COLD FRONT WILL APPROACH WEDNESDAY LATE IN THE DAY. AS
MENTIONED ABOVE TIMING APPEARS A BIT SLOWER THAN PREVIOUS MODEL
RUNS. THE STRONGEST DYNAMICS APPEAR OVER NRN LWR MI. HIRES ECMWF
SHOWS STRONGEST MOISTURE TRANSPORT AND GREATEST SHEAR ACROSS THE
NRN CWA AND NRN LWR. ADDITIONALLY...THE LLJ IS POINTED IN THAT
DIRECTION LATE IN THE DAY AND THE ACCOMPANYING SHORT WAVE IS PROGGED
TO MOVE OVER NRN LWR AS WELL. AS SUCH HIGHEST POPS WERE DIRECTED
NWD. PWATS INCREASE TO AROUND 1.75 INCHES LATE IN THE DAY AND SO
WE COULD SEE SOME HEAVY RAIN DUMPED OUT OF THEM.
WE/RE RUNNING WITH A DRY FCST THURSDAY. LATEST NAM DOES SHOW A
DECENT SHORT WAVE MOVING ACROSS THE CWA THEN. HOWEVER THE GFS DOES
NOT. CONFIDENCE WASN/T HIGH ENOUGH YET TO ADD POPS TO THE THURSDAY
GRIDS.
.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 320 AM EDT TUE SEP 4 2012
THERE ARE TWO PRIMARY CONCERNS FOR THIS PART OF THE FORECAST. THE
FIRST THE CHANCE FOR RAIN WITH DEVELOPING SYSTEM OVER THE OHIO
VALLEY FOR FRIDAY INTO SUNDAY. THE SECOND ISSUE IS JUST HOW CHILLY
DOES IT GET THIS WEEKEND?
CONSIDERABLE UNCERTAINTY REMAINS IN FORECAST FOR THE FRI THROUGH
SUNDAY PART OF THE FORECAST. THE PRIMARY ISSUE IS JUST WHAT HAPPENS
THE SYSTEM THAT DIGS INTO THE OHIO VALLEY FRIDAY INTO SATURDAY? FOR
THREE RUNS IN A ROW THE ECMWF WAS RATHER CONSISTENT WITH THE
DEVELOPING SYSTEM OVER THE SOUTHERN GREAT LAKES THEN THE 12Z RUN OF
THE ECMWF DEVELOPS THE SYSTEM FARTHER SOUTH RESULTING IN THE RAIN
MOSTLY MISSING US TO THE SOUTH. MEANWHILE THE GFS IS NOW TRACKING
THE SYSTEM FARTHER NORTH AND WOULD BRING SOME RAIN INTO THE AREA
LATER FRIDAY INTO SATURDAY BEFORE IT SINKS THE SYSTEM SOUTH OF THE
AREA SATURDAY NIGHT.
GIVEN THE UNCERTAINLY I LARGELY CONTINUED OUR GOING FORECAST AND
CALLED GOOD. THE ONE THINK THAT IS CLEAR... WE WILL NOT BE SEEING
HIGHS IN THE 80S AGAIN FRI THROUGH MONDAY AS SOUTHWEST MICHIGAN
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 122 PM EDT TUE SEP 4 2012
CONDITIONS WERE GRADUALLY IMPROVING EARLY THIS AFTERNOON...BEHIND
THE MORNING RAINS. THERE WAS A MIX OF VFR AND MVFR CONDITIONS AS
OF 17Z...AND A TREND MORE TOWARD VFR IS EXPECTED THROUGH THE
REMAINDER OF THE AFTERNOON. AREAS OF MVFR CEILINGS COULD LINGER
UNTIL 20-21Z.
MORE FOG DEVELOPMENT IS EXPECTED TONIGHT WITH HIGH DEWPOINTS
LINGERING OVER THE REGION UNDER PARTLY CLOUDY SKIES. WILL
INTRODUCE IFR VSBYS TO THE TAFS MAINLY AFTER 08Z. LOCALLY DENSE
FOG WILL AGAIN BE POSSIBLE. THE FOG SHOULD LIFT AROUND 14Z WED.
THUNDERSTORMS WILL BE POSSIBLE BY LATE WED MORNING INTO THE EARLY
AFTERNOON OVER WESTERN AND CENTRAL LOWER. HAVE ADDED VCTS TO MKG
AND GRR. THIS THREAT WILL MOVE TOWARD THE OTHER TAF SITES AFTER
18Z WED.
&&
.MARINE...
ISSUED AT 320 AM EDT TUE SEP 4 2012
WEAK PRESSURE GRADIENT WILL AGAIN RESULT IN LIGHT WINDS AND LOW
WAVES TODAY. THUNDERSTORMS AND RESULTANT HIGHER WINDS/WAVES WILL
REMAIN A THREAT THROUGH WEDNESDAY.
&&
.HYDROLOGY...
ISSUED AT 320 AM EDT TUE SEP 4 2012
LOCALLY HEAVY RAINFALL WILL BE POSSIBLE WITH SCT STORMS TODAY AND
MORE SO LATE WEDNESDAY. WIDESPREAD FLOODING IS NOT ANTICIPATED.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
UPDATE...TJT
SYNOPSIS...TJT
SHORT TERM...93
LONG TERM...WDM
AVIATION...JK
HYDROLOGY...93
MARINE...93
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1126 AM EDT TUE SEP 4 2012
.SYNOPSIS...
ISSUED AT 1125 AM EDT TUE SEP 4 2012
CLOUDS WILL DECREASE THIS AFTERNOON BEHIND SHOWERS AND
THUNDERSTORMS EXITING THE THE AREA. STRONG OR SEVERE THUNDERSTORMS
ASSOCIATED WITH A COLD FRONT ARE EXPECTED WEDNESDAY AFTERNOON AND
EVENING. BEHIND THE FRONT...SEASONABLY COOL TEMPERATURES AND SCATTERED
SHOWERS WILL FINISH THE WORK WEEK AND LAST INTO THE WEEKEND.
&&
.UPDATE...
ISSUED AT 1125 AM EDT TUE SEP 4 2012
UPDATED THE TIMING OF PRECIPITATION EXITING THE AREA. WE CONTINUE
TO ADVERTISE GRADUAL CLEARING THIS AFTERNOON WITH GREATLY REDUCED
PRECIPITATION CHANCES. WE HAVE MODERATE CONFIDENCE ABOUT THE
CLEARING AND SOMEWHAT BETTER CONFIDENCE ABOUT THE DECREASED
CHANCES FOR RAIN THIS AFTERNOON.
WE WILL HAVE TO WATCH FOR LINGERING CLOUDS THIS AFTERNOON...
PARTICULARLY OVER OUR NW ZONES. METARS AND VISIBLE SATELLITE
INDICATE A WEAK COLD FRONT SURGING SE FROM THE GREEN BAY AREA WITH
SIGNIFICANT CLOUDINESS BEHIND THIS FRONT. LATEST HRRR GUIDANCE
WASHES OUT THE FRONT THIS AFTERNOON WHEN A DIURNALLY FORCED LOW
PRESSURE AREA FORMS ACROSS LOWER MICHIGAN. THIS WOULD HELP TO
DECREASE CLOUD COVERAGE AREAWIDE...BUT OF COURSE ALSO ASSUMES
LIMITED CLOUDINESS IN THE FIRST PLACE TO HELP THE DIURNAL FORCING.
CLOUD TRENDS OVER THE NEXT FEW HOURS WILL THEREFORE BE IMPORTANT.
UPDATE ISSUED AT 610 AM EDT TUE SEP 4 2012
I UPDATED THE GRIDS AND ZONE TO PUT CONDITIONAL POPS FOR THE NEXT
FEW HOURS AS THE BAND OR RAIN AND EMBEDDED THUNDERSTORMS ASSOCIATE
WITH THE MID LEVEL TROUGH CONTINUE TO MOVE EAST ACROSS THE CWA. I
ALSO SERIOUSLY INCREASED THE QPF SINCE I HAVE RECEIVED MESONET
REPORTS LIKE .67 INCHES IN JENISON. THE INDIANA TRAILS GOLF
COURSE JUST SOUTH OF THE CITY OF GRAND RAPIDS HAD 1.01 INCHES IN
15 MINUTES. IN ANY EVENT THIS AREA OF SHOWERS IS ASSOCIATED WITH
THE 700 MB TROUGH AND THERE IS STRONG SUBSIDENCE BEHIND IT. I
BELIEVE SKIES WILL CLEAR BEHIND THIS AND ADDITIONAL CONVECTION IS
UNLIKELY MID TO LATER AFTERNOON OVER OUR CWA SUE TO THE SUBSIDENCE
BEHIND THE SHORTWAVE.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 320 AM EDT TUE SEP 4 2012
FORECAST CONCERNS DEAL WITH CONVECTIVE TRENDS TODAY AND WEDNESDAY.
NOT MANY CHANGES WERE MADE TO THE GOING FORECAST.
MODEL TRENDS THE PAST 24 HRS HAVE SLOWED THE TIMING OF THE COLD
FRONT WEDNESDAY BY A FEW HOURS AND INSTEAD OF MOVING ACROSS THE
CWA DURING THE AFTERNOON...THE FRONT MAY MOVE THROUGH DURING THE
EVENING. DUE TO DIURNAL INSTABILITY FADE...THE SEVERE THREAT HAS
EFFECTIVELY SHIFTED A BIT WWD AND THE SERN CWA HAD BEEN REMOVED
FROM THE DAY2 OUTLOOK.
LATEST REGIONAL RADAR SHOWS A BROKEN LINE OF SHOWERS AND ISOLATED
STORMS STRETCHING FROM NE LWR TO NEAR CHICAGO. THIS PCPN IS
ASSOCIATED WITH A WEAKENING FRONTAL BOUNDARY AND WILL CROSS THE
CWA TODAY. MESO ANALYSIS SHOWS EFFECTIVE SHEAR NEAR 40KTS ALONG
THE I-96 CORRIDOR ATTM. INSTABILITY HOWEVER IS LOW AND SO SVR
STORMS ARE NOT EXPECTED. THERE IS A LOW LEVEL DEW POINT GRADIENT
THAT STRETCHES ALONG I-69/96 AND WE MAY SEE A FLAREUP OF
CONVECTION AS THE ONGOING PCPN INTERACTS WITH IT.
SKIES WILL BECOME PT/MO SUNNY BEHIND THE CONVECTION TODAY AND
TEMPS WILL ONCE AGAIN CLIMB INTO THE MID TO UPPER 80S.
A STRONGER COLD FRONT WILL APPROACH WEDNESDAY LATE IN THE DAY. AS
MENTIONED ABOVE TIMING APPEARS A BIT SLOWER THAN PREVIOUS MODEL
RUNS. THE STRONGEST DYNAMICS APPEAR OVER NRN LWR MI. HIRES ECMWF
SHOWS STRONGEST MOISTURE TRANSPORT AND GREATEST SHEAR ACROSS THE
NRN CWA AND NRN LWR. ADDITIONALLY...THE LLJ IS POINTED IN THAT
DIRECTION LATE IN THE DAY AND THE ACCOMPANYING SHORT WAVE IS PROGD
TO MOVE OVER NRN LWR AS WELL. AS SUCH HIGHEST POPS WERE DIRECTED
NWD. PWATS INCREASE TO AROUND 1.75 INCHES LATE IN THE DAY AND SO
WE COULD SEE SOME HEAVY RAIN DUMPED OUT OF THEM.
WE/RE RUNNING WITH A DRY FCST THURSDAY. LATEST NAM DOES SHOW A
DECENT SHORT WAVE MOVING ACROSS THE CWA THEN. HOWEVER THE GFS DOES
NOT. CONFIDENCE WASN/T HIGH ENOUGH YET TO ADD POPS TO THE THURSDAY
GRIDS.
.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 320 AM EDT TUE SEP 4 2012
THERE ARE TWO PRIMARY CONCERNS FOR THIS PART OF THE FORECAST. THE
FIRST THE CHANCE FOR RAIN WITH DEVELOPING SYSTEM OVER THE OHIO
VALLEY FOR FRIDAY INTO SUNDAY. THE SECOND ISSUE IS JUST HOW CHILLY
DOES IT GET THIS WEEKEND?
CONSIDERABLE UNCERTAINTY REMAINS IN FORECAST FOR THE FRI THROUGH
SUNDAY PART OF THE FORECAST. THE PRIMARY ISSUE IS JUST WHAT HAPPENS
THE SYSTEM THAT DIGS INTO THE OHIO VALLEY FRIDAY INTO SATURDAY? FOR
THREE RUNS IN A ROW THE ECMWF WAS RATHER CONSISTENT WITH THE
DEVELOPING SYSTEM OVER THE SOUTHERN GREAT LAKES THEN THE 12Z RUN OF
THE ECMWF DEVELOPS THE SYSTEM FARTHER SOUTH RESULTING IN THE RAIN
MOSTLY MISSING US TO THE SOUTH. MEANWHILE THE GFS IS NOW TRACKING
THE SYSTEM FARTHER NORTH AND WOULD BRING SOME RAIN INTO THE AREA
LATER FRIDAY INTO SATURDAY BEFORE IT SINKS THE SYSTEM SOUTH OF THE
AREA SATURDAY NIGHT.
GIVEN THE UNCERTAINLY I LARGELY CONTINUED OUR GOING FORECAST AND
CALLED GOOD. THE ONE THINK THAT IS CLEAR... WE WILL NOT BE SEEING
HIGHS IN THE 80S AGAIN FRI THROUGH MONDAY AS SOUTHWEST MICHIGAN
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 610 AM EDT TUE SEP 4 2012
I WILL TIME THE CONVECTION ACROSS THE TAF SITES THIS MORNING AND
HAVE CLEARING FROM WEST TO EAST AT THE TAF SITES THIS AFTERNOON
DUE TO THE 700 MB TROUGH MOVING EAST OF THE AREA. I DO NOT EXPECT
ANY DEVELOPMENT OF THE STORMS THIS AFTERNOON.
INCREASING WINDS IN THE BOUNDARY LAYER AFTER 06Z SHOULD KEEP FOG
FROM DEVELOPING AT THE TAF SITES TONIGHT. THE NEXT AREA OF RAIN
WILL MOVE IN WEDNESDAY AFTERNOON WITH THE CONVECTION ON THE COLD
FRONT.
&&
.MARINE...
ISSUED AT 320 AM EDT TUE SEP 4 2012
WEAK PRESSURE GRADIENT WILL AGAIN RESULT IN LIGHT WINDS AND LOW
WAVES TODAY. THUNDERSTORMS AND RESULTANT HIGHER WINDS/WAVES WILL
REMAIN A THREAT THROUGH WEDNESDAY.
&&
.HYDROLOGY...
ISSUED AT 320 AM EDT TUE SEP 4 2012
LOCALLY HEAVY RAINFALL WILL BE POSSIBLE WITH SCT STORMS TODAY AND
MORE SO LATE WEDNESDAY. WIDESPREAD FLOODING IS NOT ANTICIPATED.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
UPDATE...TJT
SYNOPSIS...TJT
SHORT TERM...93
LONG TERM...WDM
AVIATION...WDM
HYDROLOGY...93
MARINE...93
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
728 AM EDT TUE SEP 4 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 438 AM EDT TUE SEP 4 2012
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW FAST ZONAL FLOW
OVER THE NRN TIER CONUS TO THE S OF DEEP OCCLUDED LO CENTERED OVER
NRN MANITOBA. DISTURBANCE/AREA OF DEEPER MSTR RESPONSIBLE FOR
SHRA/TS YDAY HAS PUSHED TO THE E AND GIVEN WAY TO WEAK HI PRES AND
DRIER AIR. SOME AREAS OF DENSE FOG HAVE DVLPD OVER MAINLY THE ERN
AND CNTRL CWA WITH LGT WINDS WHERE THE DRYING ALF HAS OUTRUN THE
NEAR SFC DRYING. FOG APPEARS LESS PREVALENT OVER THE W WHERE DRIER
LLVL AIR APRNT ON THE 00Z INL/MPX RAOBS HAS MADE GREATER INROADS.
DESPITE THE PRESENCE OF THIS DRY AIR...SOME SHRA/A FEW TS ARE NOTED
OVER NW MN NEAR AN INCOMING SHRTWV/SFC LO PRES TROF IN AREA WHERE
NAM/GFS SHOW SOME H85 THETA E ADVECTION. SOME PATCHY MID/HI CLDS
AHEAD OF THIS DISTURBANCE ARE DRIFING INTO THE WRN CWA. FARTHER TO
THE NW...ANOTHER STRONGER SHRTWV IS OVER SASKATCHEWAN AND MOVING
SEWD ON THE SRN FLANK OF CLOSED LO IN MANITOBA.
EARLY THIS MORNING...OPTED TO ISSUE AN SPS FOR MUCH OF THE E AND
CNTRL CWA TO HIGHLIGHT LOCALLY DENSE FOG.
TODAY...EXPECT FOG TO BURN OFF THIS MRNG WITH ONSET OF DAYTIME
HEATING. CONCERN THEN TURNS TO IMPACT OF SHRTWV NOW MOVING E THRU
NRN MN. SEVERAL MODELS...ESPECIALLY THE 00Z NAM/CNDN...SHOW SOME
FAIRLY SHARP DEEP LYR QVECTOR CNVGC/H3-2 DVGC/AXIS OF HIER H85-5 RH
ASSOCIATED WITH DPVA/H85 THETA E ADVECTION IMPACTING THE WRN ZNS
THIS AFTN INTO THE EARLY EVNG. IN FACT...RECENT SPC CONVECTIVE
OUTLOOK HAS THE FAR W IN A SLIGHT RISK FOR SVR STORMS LATE THIS
AFTN/EARLY EVNG. MODIFIED GFS FCST SDNG FOR IWD LATE IN THE AFTN
YIELDS SBCAPE NEAR 1900 J/KG FOR SFC T/TD 84/60 UNDER STEEP MID LVL
LAPSE RATES. THE NAM INDICATES 2000-2500 J/KG MUCAPE IN THIS AREA. A
POSITIVE FOR SVR STORMS IS THE STEEP MID LVL LAPSE RATES/PRESENCE OF
DRY AIR IN THE MID LVLS WITH SFC-10K FT DELTA THETA E 15-20C AND
INVERTED V LOOK TO THE LLVL TEMP/DEWPT PROFILES THAT WOULD ENHANCE
THE THREAT OF GUSTY WINDS. ON THE OTHER HAND...GENERALY DRYNESS OF
THE ATMOSPHERE WL TEND TO LIMIT THE COVERAGE OF THE STORMS. ALSO
DEEP LYR SHEAR IS FCST TO BE UP TO 30 KTS...A BIT MARGINAL BUT
PROBABLY ENUF TO ALLOW FOR AT LEAST PULSE SVR STORMS. OTRW...EXPECT
ANOTHER WARM DAY WITH H85 TEMPS IN THE 16-18C RANGE SUPPORTING HI
TEMPS IN THE 80S AWAY FM LK BREEZES THAT WL TEND TO FORM OFF MAINLY
LK MI WITH SSE H925 FLOW.
TNGT...EXPECT BAND OF SCT SHRA/TS MOVING W-E INTO THE E HALF TO
SLOWLY DIMINISH WITH LOSS OF DAYTIME HEATING/SHIFT OF SUPPORTING
DEEP LYR QVECTOR CNVGC TO THE N INTO ONTARIO. WITH SOME DNVA/
NEGATIVE H85 THETA E ADVECTION/DEEP LYR QVECTOR DVGC FOLLOWING THIS
BAND... EXPECT A PERIOD OF DRY WX. HOWEVER...APRCH OF SHARPER SHRTWV
NOW MOVING SEWD THRU SASKATCHEWAN AND VIGOROUS DPVA/DEEP LYR QVECTOR
CNVGC/SOME UPR DVGC WILL BRING BACK A THREAT OF SHRA/TS OVER THE W
LATE. LIMITING FACTORS WILL BE LIMITED MSTR RETURN...SOME GUIDANCE
ACTUALLY SHOWS NEGATIVE H85 THETA E ADVECTION...AND ARRIVAL OF THE
DYNAMICS AT TIME OF MIN DIURNAL HEATING.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 438 AM EDT TUE SEP 4 2012
STARTING WITH WEDNESDAY...MOST OF THE GUIDANCE BRINGS A MODEST COLD
FRONT THROUGH UPPER MI LATE WEDNESDAY MORNING INTO THE AFTERNOON. AS
FOR MOISTURE AND INSTABILITY...850MB THETA E RIDGE SPRAWLS ITSELF
ACROSS THE CWA TUESDAY NIGHT. PLENTY OF MOIST AIR WILL BE IN PLACE
AS THE NOSE OF AN 850MB JET AIMS INTO SOUTHWESTERN UPPER MI...WITH
PWATS EXPECTED TO BE 130-150 PERCENT OF NORMAL. SFC BASED CAPE
DURING THE EARLY AFTERNOON IS AROUND 1000-1500 J/KG...AND MUCAPE IS
UPWARDS OF 1800 J/KG. HIGHEST VALUES ARE IN THE SOUTH-SOUTH CENTRAL
PORTIONS OF THE CWA. LOOKING AT FORECAST SOUNDINGS IT SEEMS WITH
SHORTWAVE MOVING THROUGH DURING PEAK HEATING WE SHOULD HAVE ENOUGH
GUSTO TO BREAK THE WEAK CAP THAT WILL BE IN PLACE. AS FAR AS ANY
SUPPORT GOES...300MB JET STREAK SLIDES ACROSS THE CWA IN THE
AFTERNOON...WITH RIGHT ENTRANCE REGION DYNAMICS IN PLAY ACROSS
MAINLY THE SOUTH CENTRAL PORTION OF THE CWA. ECMWF HAS 500MB VORT
MAXIMUM SLIDING INTO THE WEST HALF OF UPPER MI BY 18Z. WITH THE
300/850 MB JET STREAKS MOVING THROUGH 0-6 KM SHEAR IS AROUND 25-35
KNOTS. OVERALL THIS GIVES US A MODERATE CAPE/SHEAR ENVIRONMENT AND
POTENTIAL FOR A SEVERE LINE OF STORMS...LIKELY DEVELOPING ACROSS THE
SOUTHERN PORTIONS OF THE CWA WHERE LIFT AND INSTABILITY IS
MAXIMIZED.
THURSDAY WE DEAL WITH COOLER DRY AIR BEHIND THE FRONT/IN THE WAKE OF
THE LOW PRESSURE SYSTEM NEAR JAMES BAY. DRY AIR PUNCHES IN ALOFT
OVERNIGHT ON WEDNESDAY...SO IT LOOKS LIKE THURSDAY WILL BE
RELATIVELY QUIET IN TERMS OF PRECIPITATION. PWATS DROP DOWN TO NEAR
70 PERCENT OF NORMAL AT TIMES AS SURFACE HIGH PRESSURE MOVING ACROSS
THE MIDWEST TRIES TO RIDGE INTO UPPER MI. BY FRIDAY THE LOW BEGINS
TO OCCLUDE NEAR JAMES BAY...SWINGING AN UPPER LEVEL TROUGH ACROSS
UPPER MICHIGAN ONCE MORE. ECMWF GENERATES PRECIPITATION ACROSS
CENTRAL AND EASTERN PRECIPITATION FOR THE DAY ON FRIDAY...SUPPORTED
BY MODERATE 850-500MB QVECTOR CONVERGENCE AND LINGERING MOISTURE
/PWATS AROUND 110 PERCENT OF NORMAL/. WITH NORTHWEST FLOW AND
LAKE-850MB TEMP DIFFERENCES AROUND 15-18C...EXPECT A LAKE EFFECT
COMPONENT TO PRECIPITATION NEAR LAKE SUPERIOR. ADDITIONALLY...STRONG
ONSHORE FLOW WILL GENERATE WAVES AS HIGH AS 3 TO 5 FEET IN THE ALGER
AND EASTERN MARQUETTE COUNTY SURF ZONE FRIDAY INTO SATURDAY
MORNING...LEADING TO THE POSSIBILITY FOR RIP CURRENT DEVELOPMENT.
WITH THE COLD FRONT PASSING WEDNESDAY AFTERNOON/EVENING TEMPERATURES
WILL BE MORE FALL LIKE...WITH HIGHS IN THE 60S AND LOW 70S THROUGH
THE REMAINDER OF THE PERIOD. ALONG WITH FALL LIKE TEMPERATURES...WE
CAN EXPECT FALL-LIKE FEATURES. FRIDAY THERE IS AN ELEVATED POTENTIAL
FOR WATERSPOUT DEVELOPMENT AS COOLER TEMPERATURES ALOFT MOVE IN OVER
THE STILL WARM LAKE. FORECASTS PER THE INTERNATIONAL CENTRE FOR
WATERSPOUT RESEARCH ARE STILL INDICATING THAT CONDITIONS WILL BE
FAVORABLE FOR THEIR DEVELOPMENT.
AS THE SFC/500MB HIGH PRESSURE RIDGE OVER THE NORTHERN PLAINS BUILDS
INTO UPPER MICHIGAN FOR THE WEEKEND AND THROUGH THE FIRST PORTION OF
THE WORK WEEK...EXPECT CONDITIONS TO REMAIN FAIRLY DRY. THE ONLY
EXCEPTION IS THE LOW PRESSURE SYSTEM THAT DEVELOPS IN THE OHIO
VALLEY FRIDAY...LINGERING OVER LOWER MI THROUGH THE EXTENDED. THIS
COULD BRING SLIGHT CHANCE POPS OVER THE EASTERN U.P. FOR SATURDAY
INTO MONDAY. FOR NOW WITH MODEL DIFFERENCES IN LOCATION AND TIMING
OF THIS PRECIP WILL KEEP THE MODEL CONSENSUS IN FORECAST UNTIL THE
FINER DETAILS CAN BE NARROWED DOWN.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 728 AM EDT TUE SEP 4 2012
EXPECT FOG IMPACTING SAW/CMX TO BURN OFF BY MID MRNG WITH THE ONSET
OF DAYTIME HEATING. AN APRCHG LO PRES TROF WILL BRING THE THREAT OF
SHRA/SOME TS TO ALL 3 SITES THIS AFTN/EVNG BEFORE THE TROF MOVES TO
THE E THIS EVNG AND ENDS THE THREAT W-E. SINCE IWD HAS THE BEST SHOT
TO SEE SOME TS...ADDED AN EXPLICIT FCST FOR TS TIMING THERE FOR
20Z-22Z. WITH LGT WINDS/DRYING ALF IN THE WAKE OF THE TROF...MORE
FOG MAY FORM OVERNGT. BUT THE APRCH OF ANOTHER LO PRES TROF MAY
BRING MORE CLDS/-SHRA TO IWD LATE IN THE FCST PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 438 AM EDT TUE SEP 4 2012
EXPECT SSW WINDS TO INCREASE UP TO 20 KTS TODAY MAINLY OVER THE E
HALF IN ADVANCE OF AN APPROACHING LO PRES TROF. THESE STRONGER WINDS
WILL BRING DRIER AIR OVER THE E HALF OF THE LAKE AND DISSIPATE FOG
THAT DEVELOPED DURING THE NIGHT IN THE WAKE OF SHOWERS THAT FELL ON
MON. ALTHOUGH WINDS WILL DIMINISH FOR A TIME WITH THE PASSAGE OF THE
TROF...EXPECT W TO NW WINDS IN ITS WAKE LATE WED THRU THU TO
INCREASE UP TO 20 TO 25 KTS AS COOLER AIR ARRIVES OVER THE
RELATIVELY WARM LAKE WATERS AND ENHANCES MIXING. ALTHOUGH WINDS MAY
DIMINISH FOR A TIME ON THU NIGHT AS ANOTHER TROF SWINGS OVER LAKE
SUPERIOR...PLAN ON ANOTHER ROUND OF STRONGER NW WINDS UP TO 25 KTS
ON FRI IN ITS WAKE. THE APPROACH OF HIGH PRESSURE/A WEAKENING PRES
GRADIENT THIS WEEKEND WILL CAUSE WINDS TO SLOWLY DIMINISH.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...MCD
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
440 AM EDT TUE SEP 4 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 438 AM EDT TUE SEP 4 2012
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW FAST ZONAL FLOW
OVER THE NRN TIER CONUS TO THE S OF DEEP OCCLUDED LO CENTERED OVER
NRN MANITOBA. DISTURBANCE/AREA OF DEEPER MSTR RESPONSIBLE FOR
SHRA/TS YDAY HAS PUSHED TO THE E AND GIVEN WAY TO WEAK HI PRES AND
DRIER AIR. SOME AREAS OF DENSE FOG HAVE DVLPD OVER MAINLY THE ERN
AND CNTRL CWA WITH LGT WINDS WHERE THE DRYING ALF HAS OUTRUN THE
NEAR SFC DRYING. FOG APPEARS LESS PREVALENT OVER THE W WHERE DRIER
LLVL AIR APRNT ON THE 00Z INL/MPX RAOBS HAS MADE GREATER INROADS.
DESPITE THE PRESENCE OF THIS DRY AIR...SOME SHRA/A FEW TS ARE NOTED
OVER NW MN NEAR AN INCOMING SHRTWV/SFC LO PRES TROF IN AREA WHERE
NAM/GFS SHOW SOME H85 THETA E ADVECTION. SOME PATCHY MID/HI CLDS
AHEAD OF THIS DISTURBANCE ARE DRIFING INTO THE WRN CWA. FARTHER TO
THE NW...ANOTHER STRONGER SHRTWV IS OVER SASKATCHEWAN AND MOVING
SEWD ON THE SRN FLANK OF CLOSED LO IN MANITOBA.
EARLY THIS MORNING...OPTED TO ISSUE AN SPS FOR MUCH OF THE E AND
CNTRL CWA TO HIGHLIGHT LOCALLY DENSE FOG.
TODAY...EXPECT FOG TO BURN OFF THIS MRNG WITH ONSET OF DAYTIME
HEATING. CONCERN THEN TURNS TO IMPACT OF SHRTWV NOW MOVING E THRU
NRN MN. SEVERAL MODELS...ESPECIALLY THE 00Z NAM/CNDN...SHOW SOME
FAIRLY SHARP DEEP LYR QVECTOR CNVGC/H3-2 DVGC/AXIS OF HIER H85-5 RH
ASSOCIATED WITH DPVA/H85 THETA E ADVECTION IMPACTING THE WRN ZNS
THIS AFTN INTO THE EARLY EVNG. IN FACT...RECENT SPC CONVECTIVE
OUTLOOK HAS THE FAR W IN A SLIGHT RISK FOR SVR STORMS LATE THIS
AFTN/EARLY EVNG. MODIFIED GFS FCST SDNG FOR IWD LATE IN THE AFTN
YIELDS SBCAPE NEAR 1900 J/KG FOR SFC T/TD 84/60 UNDER STEEP MID LVL
LAPSE RATES. THE NAM INDICATES 2000-2500 J/KG MUCAPE IN THIS AREA. A
POSITIVE FOR SVR STORMS IS THE STEEP MID LVL LAPSE RATES/PRESENCE OF
DRY AIR IN THE MID LVLS WITH SFC-10K FT DELTA THETA E 15-20C AND
INVERTED V LOOK TO THE LLVL TEMP/DEWPT PROFILES THAT WOULD ENHANCE
THE THREAT OF GUSTY WINDS. ON THE OTHER HAND...GENERALY DRYNESS OF
THE ATMOSPHERE WL TEND TO LIMIT THE COVERAGE OF THE STORMS. ALSO
DEEP LYR SHEAR IS FCST TO BE UP TO 30 KTS...A BIT MARGINAL BUT
PROBABLY ENUF TO ALLOW FOR AT LEAST PULSE SVR STORMS. OTRW...EXPECT
ANOTHER WARM DAY WITH H85 TEMPS IN THE 16-18C RANGE SUPPORTING HI
TEMPS IN THE 80S AWAY FM LK BREEZES THAT WL TEND TO FORM OFF MAINLY
LK MI WITH SSE H925 FLOW.
TNGT...EXPECT BAND OF SCT SHRA/TS MOVING W-E INTO THE E HALF TO
SLOWLY DIMINISH WITH LOSS OF DAYTIME HEATING/SHIFT OF SUPPORTING
DEEP LYR QVECTOR CNVGC TO THE N INTO ONTARIO. WITH SOME DNVA/
NEGATIVE H85 THETA E ADVECTION/DEEP LYR QVECTOR DVGC FOLLOWING THIS
BAND... EXPECT A PERIOD OF DRY WX. HOWEVER...APRCH OF SHARPER SHRTWV
NOW MOVING SEWD THRU SASKATCHEWAN AND VIGOROUS DPVA/DEEP LYR QVECTOR
CNVGC/SOME UPR DVGC WILL BRING BACK A THREAT OF SHRA/TS OVER THE W
LATE. LIMITING FACTORS WILL BE LIMITED MSTR RETURN...SOME GUIDANCE
ACTUALLY SHOWS NEGATIVE H85 THETA E ADVECTION...AND ARRIVAL OF THE
DYNAMICS AT TIME OF MIN DIURNAL HEATING.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 438 AM EDT TUE SEP 4 2012
STARTING WITH WEDNESDAY...MOST OF THE GUIDANCE BRINGS A MODEST COLD
FRONT THROUGH UPPER MI LATE WEDNESDAY MORNING INTO THE AFTERNOON. AS
FOR MOISTURE AND INSTABILITY...850MB THETA E RIDGE SPRAWLS ITSELF
ACROSS THE CWA TUESDAY NIGHT. PLENTY OF MOIST AIR WILL BE IN PLACE
AS THE NOSE OF AN 850MB JET AIMS INTO SOUTHWESTERN UPPER MI...WITH
PWATS EXPECTED TO BE 130-150 PERCENT OF NORMAL. SFC BASED CAPE
DURING THE EARLY AFTERNOON IS AROUND 1000-1500 J/KG...AND MUCAPE IS
UPWARDS OF 1800 J/KG. HIGHEST VALUES ARE IN THE SOUTH-SOUTH CENTRAL
PORTIONS OF THE CWA. LOOKING AT FORECAST SOUNDINGS IT SEEMS WITH
SHORTWAVE MOVING THROUGH DURING PEAK HEATING WE SHOULD HAVE ENOUGH
GUSTO TO BREAK THE WEAK CAP THAT WILL BE IN PLACE. AS FAR AS ANY
SUPPORT GOES...300MB JET STREAK SLIDES ACROSS THE CWA IN THE
AFTERNOON...WITH RIGHT ENTRANCE REGION DYNAMICS IN PLAY ACROSS
MAINLY THE SOUTH CENTRAL PORTION OF THE CWA. ECMWF HAS 500MB VORT
MAXIMUM SLIDING INTO THE WEST HALF OF UPPER MI BY 18Z. WITH THE
300/850 MB JET STREAKS MOVING THROUGH 0-6 KM SHEAR IS AROUND 25-35
KNOTS. OVERALL THIS GIVES US A MODERATE CAPE/SHEAR ENVIRONMENT AND
POTENTIAL FOR A SEVERE LINE OF STORMS...LIKELY DEVELOPING ACROSS THE
SOUTHERN PORTIONS OF THE CWA WHERE LIFT AND INSTABILITY IS
MAXIMIZED.
THURSDAY WE DEAL WITH COOLER DRY AIR BEHIND THE FRONT/IN THE WAKE OF
THE LOW PRESSURE SYSTEM NEAR JAMES BAY. DRY AIR PUNCHES IN ALOFT
OVERNIGHT ON WEDNESDAY...SO IT LOOKS LIKE THURSDAY WILL BE
RELATIVELY QUIET IN TERMS OF PRECIPITATION. PWATS DROP DOWN TO NEAR
70 PERCENT OF NORMAL AT TIMES AS SURFACE HIGH PRESSURE MOVING ACROSS
THE MIDWEST TRIES TO RIDGE INTO UPPER MI. BY FRIDAY THE LOW BEGINS
TO OCCLUDE NEAR JAMES BAY...SWINGING AN UPPER LEVEL TROUGH ACROSS
UPPER MICHIGAN ONCE MORE. ECMWF GENERATES PRECIPITATION ACROSS
CENTRAL AND EASTERN PRECIPITATION FOR THE DAY ON FRIDAY...SUPPORTED
BY MODERATE 850-500MB QVECTOR CONVERGENCE AND LINGERING MOISTURE
/PWATS AROUND 110 PERCENT OF NORMAL/. WITH NORTHWEST FLOW AND
LAKE-850MB TEMP DIFFERENCES AROUND 15-18C...EXPECT A LAKE EFFECT
COMPONENT TO PRECIPITATION NEAR LAKE SUPERIOR. ADDITIONALLY...STRONG
ONSHORE FLOW WILL GENERATE WAVES AS HIGH AS 3 TO 5 FEET IN THE ALGER
AND EASTERN MARQUETTE COUNTY SURF ZONE FRIDAY INTO SATURDAY
MORNING...LEADING TO THE POSSIBILITY FOR RIP CURRENT DEVELOPMENT.
WITH THE COLD FRONT PASSING WEDNESDAY AFTERNOON/EVENING TEMPERATURES
WILL BE MORE FALL LIKE...WITH HIGHS IN THE 60S AND LOW 70S THROUGH
THE REMAINDER OF THE PERIOD. ALONG WITH FALL LIKE TEMPERATURES...WE
CAN EXPECT FALL-LIKE FEATURES. FRIDAY THERE IS AN ELEVATED POTENTIAL
FOR WATERSPOUT DEVELOPMENT AS COOLER TEMPERATURES ALOFT MOVE IN OVER
THE STILL WARM LAKE. FORECASTS PER THE INTERNATIONAL CENTRE FOR
WATERSPOUT RESEARCH ARE STILL INDICATING THAT CONDITIONS WILL BE
FAVORABLE FOR THEIR DEVELOPMENT.
AS THE SFC/500MB HIGH PRESSURE RIDGE OVER THE NORTHERN PLAINS BUILDS
INTO UPPER MICHIGAN FOR THE WEEKEND AND THROUGH THE FIRST PORTION OF
THE WORK WEEK...EXPECT CONDITIONS TO REMAIN FAIRLY DRY. THE ONLY
EXCEPTION IS THE LOW PRESSURE SYSTEM THAT DEVELOPS IN THE OHIO
VALLEY FRIDAY...LINGERING OVER LOWER MI THROUGH THE EXTENDED. THIS
COULD BRING SLIGHT CHANCE POPS OVER THE EASTERN U.P. FOR SATURDAY
INTO MONDAY. FOR NOW WITH MODEL DIFFERENCES IN LOCATION AND TIMING
OF THIS PRECIP WILL KEEP THE MODEL CONSENSUS IN FORECAST UNTIL THE
FINER DETAILS CAN BE NARROWED DOWN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 137 AM EDT TUE SEP 4 2012
EXPECT VLIFR CONDITIONS/FOG THRU SUNRISE AT SAW BEFORE DAYTIME
HEATING BURNS THIS FOG OFF AND BRINGS A RETURN OF VFR CONDITIONS.
DRY LLVL AIR SHOWN ON THE 00Z MPX/INL RAOBS HAS MADE GREATER INROADS
INTO WRN UPR MI...SO LOOK FOR ONLY PTCHY FOG/POSSIBLE MVFR VSBYS AT
THESE LOCATIONS. THE APRCH OF A LO PRES TROF THIS AFTN IN TANDEM
WITH DAYTIME HEATING MAY RESULT IN SOME SHRA/EVEN A TS AT ALL 3
SITES THIS AFTN/EVNG...BUT RELATIVE DRYNESS OF THE LLVLS SHOULD
MAINTAIN VFR CONDITIONS. SOME FOG MAY DVLP AT IWD LATER THIS EVNG
WITH SOME DRYING ALF OVER LINGERNIG LLVL MSTR.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 438 AM EDT TUE SEP 4 2012
EXPECT SSW WINDS TO INCREASE UP TO 20 KTS TODAY MAINLY OVER THE E
HALF IN ADVANCE OF AN APPROACHING LO PRES TROF. THESE STRONGER WINDS
WILL BRING DRIER AIR OVER THE E HALF OF THE LAKE AND DISSIPATE FOG
THAT DEVELOPED DURING THE NIGHT IN THE WAKE OF SHOWERS THAT FELL ON
MON. ALTHOUGH WINDS WILL DIMINISH FOR A TIME WITH THE PASSAGE OF THE
TROF...EXPECT W TO NW WINDS IN ITS WAKE LATE WED THRU THU TO
INCREASE UP TO 20 TO 25 KTS AS COOLER AIR ARRIVES OVER THE
RELATIVELY WARM LAKE WATERS AND ENHANCES MIXING. ALTHOUGH WINDS MAY
DIMINISH FOR A TIME ON THU NIGHT AS ANOTHER TROF SWINGS OVER LAKE
SUPERIOR...PLAN ON ANOTHER ROUND OF STRONGER NW WINDS UP TO 25 KTS
ON FRI IN ITS WAKE. THE APPROACH OF HIGH PRESSURE/A WEAKENING PRES
GRADIENT THIS WEEKEND WILL CAUSE WINDS TO SLOWLY DIMINISH.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...MCD
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
138 AM EDT TUE SEP 4 2012
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 517 PM EDT MON SEP 3 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW WSW FLOW OVER THE UPPER
GREAT LAKES BTWN UPPER RIDGE EXTENDING FROM THE PLAINS TO THE LWR
LAKES AND A DEEP...OCCLUDED LOW OVER NRN MANITOBA. NARROW MOISTURE
RIBBON HAS SHIFTED INTO THE UPPER LAKES IN ASSOCIATION WITH
DISSIPATING SFC TROF ORIGINALLY ASSOCIATED WITH DEEP SYSTEM IN NRN
MANITOBA. LEFT EXIT OF UPPER JET STREAK AIDED EARLY MORNING
CONVECTION OVER NW UPPER MI/LAKE SUPERIOR. BASED ON LATEST RUC
ANALYSIS...IT APPEARS CONVECTION THAT HAS BEEN DEVELOPING MAY BE
GETTING SOME SUPPORT FROM THE RIGHT ENTRANCE OF JET STREAK NOW.
ONGOING CONVECTION OVER ROUGHLY THE SE HALF OF THE FCST AREA WILL
CONTINUE SETTLE SE INTO THE EVENING HRS. WITH MUCAPE ON THE ORDER
OF 1000-2000J/KG AND DEEP LAYER SHEAR AROUND 40KT...ORGANIZED STORMS
WILL CONTINUE ALONG WITH THE POTENTIAL OF SVR FOR THE NEXT SEVERAL
HRS. SHRA/TSRA SHOULD BE OUT OF THE SE/SCNTRL FCST AREA MID TO LATE
EVENING. HEALTHY DRYING ALOFT (NOTE UPSTREAM 12Z KINL SOUNDING) WILL
THEN OCCUR THRU THE NIGHT...ENDING ANY THREAT OF ADDITIONAL PCPN.
CONSIDERING DRYNESS OF INCOMING AIR MASS AND LIGHT/CALM WIND
UNDER BUBBLE SFC HI PRES BUILDING INTO THE AREA...FAVORED
THE LOWER SIDE OF AVBL GUIDANCE FOR MIN TEMPS. VIGOROUS DRYING
ALOFT/LIGHT WINDS FAVOR FOG DEVELOPMENT...ESPECIALLY SINCE THERE HAS
BEEN RAINFALL TODAY. THUS...MAINTAINED MENTION OF AREAS OF FOG OVER
MUCH OF THE INTERIOR.
ON TUE...ATTENTION TURNS TO A COUPLE OF SHORTWAVES EXTENDING FROM
ND INTO MT. ONE OR BOTH OF THESE WAVES WILL REACH THE UPPER LAKES
TUE AND WILL LIKELY PROVIDE SUFFICIENT FORCING FOR ISOLD/SCT
CONVECTION. GIVEN THAT CONVECTION IS CURRENTLY BEING OBSERVED OVER
THE ERN DAKOTAS AHEAD OF THE FIRST WAVE...BUMPED POPS UP INTO THE
CHC CATEGORY OVER ROUGHLY THE W HALF OF THE FCST AREA TUE. ALTHOUGH
NAM/GFS MLCAPES ARE IN THE 1500-2500J/KG RANGE...DEEP LAYER SHEAR IS
UNDER 30KT WHICH WILL WORK TO LIMIT MORE WIDESPREAD SVR POTENTIAL.
NONETHELESS...IF STORMS DO DEVELOP...MAY SEE SOME ISOLD/PULSE TYPE
SVR STORMS TUE AFTN.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 517 PM EDT MON SEP 3 2012
BASIC OUTLOOK OF THE LONG TERM NOT TOO DIFFERENT FROM YESTERDAY. WV
LOOP AND 12Z RAOBS INDICATE PAIR OF UPPER LOWS IN CANADA FROM
NORTHERN MANITOBA INTO NORTHERN BRITISH COLUMBIA. MANITOBA LOW STAYS
FAIRLY STATIONARY THROUGH WEDNESDAY WHILE THE BRITISH COLUMBIA LOW
DIGS TO ITS SOUTH AND EVENTUALLY SOUTHEAST INTO NORTHERN ONTARIO. AS
THIS OCCURS...STRONG SFC-H85 COLD FRONT MARCHES ACROSS UPPER GREAT
LAKES WEDNESDAY AFTERNOON AND EVENING. DYNAMICS PROVIDED BY 12-HR
H5 HEIGHT FALLS TO 60M AND A COUPLED JET STRUCTURE COMBINE WITH
SFC-H85 FRONT AND SURGE OF H85 MOISTURE TRANSPORT TO GENERATE SHRA
ALONG AND AHEAD OF THE FRONT. DEPENDING ON TIMING OF FRONT AND
HEATING AHEAD OF FRONT...TSRA COULD BE STRONG GIVEN 0-6KM CAPES UP
TO 1500 J/KG AND AS H85 JET INCREASES OVER CWA AND BECOMES PARALLEL
TO THE H5 FLOW. SETUP IS FAVORABLE FOR DYNAMICALLY DRIVEN BOW-ECHO
SOMEWHERE OVER THE AREA AS THERE IS A DRY H7-H5 LAYER PUNCHING INTO
THE AREA FROM THE WEST WITH DWPNT DEPRESSIONS OVR 20C BY LATER AFTN.
BEST CHANCE FOR SEVERE PROBABLY ENDS UP SOUTH AND EAST OF CWA WHERE
GREATEST MLCAPES ARE FORECAST IN THE AFTN. AT THE LEAST...LIKELY
POPS ARE CERTAINLY WARRANTED AS THE SFC-H85 FRONT WORKS ACROSS THE
CWA.
ONCE FRONT PLOWS THROUGH MAY SEE HIGHER WIND GUSTS WEDNESDAY NIGHT
INTO THURSDAY AS SFC LOW WRAPS UP BTWN LAKE SUPERIOR AND HUDSON BAY.
GFS/ECMWF H85 WINDS NOT THAT STRONG...MAYBE UP TO 30 KTS...SO DOES
NOT APPEAR THAT WINDS WILL BECOME TOO STRONG. IF THE SFC LOW ENDS UP
DEEPENING CLOSER TO LK SUPERIOR...COULD SEE NORTHWESTERLY WIND GUSTS
ALONG LK SUPERIOR 40-45 MPH. AT THIS POINT...WX ON THURSDAY SHOULD
END UP QUIET AS UPR MICHIGAN IS BTWN THE STRONG SHORTWAVE TROUGH
THAT MOVES THROUGH MID WEEK AND RE-INFORCING TROUGH THAT IS FORECAST
TO ROTATE THROUGH ON FRIDAY. FORECAST SOUNDINGS FROM GFS AND OUTPUT
FROM GEM-NHEM INDICATE SOME POTENTIAL FOR LIGHT SHRA OVER THE
EASTERN CWA IN WEAK AREA OF LOW-LEVEL CONVERGENCE. SEEMS GREATER
CHANCE OF SHRA ARRIVES ON FRIDAY WITH THE INCOMING TROUGH AND
INDICATION OF SHORTWAVE RIDING THROUGH IN WEST/NORTHWEST FLOW
ALOFT. THIS FORCING ALONG WITH INCREASING OVER-WATER INSTABILITY
WITH LAKE EFFECT CAPES PUSHING AOA 500J/KG SUGGESTS HYBRID LATE
SUMMER AND EARLY FALL TYPE SHRA AND MAYBE EVEN MENTION OF TSRA
GIVEN LAKE INDUCED EQL OVER 20KFT WHICH PUSHES CONVECTIVE DEPTH
BLO 0C.
GIVEN LAKE-H85 DELTA T AOA 15C...DEEP LAKE INDUCED CLOUD DEPTH...AND
WINDS WITHIN THE MIXED LAYER STAYING BLO 25 KTS...PARAMETERS STILL
LINE UP FOR WATERSPOUT POTENTIAL ON FRIDAY...ESPECIALLY IF SUBTLE
LOW-LEVEL TROUGH THAT IS SHOWING UP IN MODELS OVER EASTERN LK
SUPERIOR/EASTERN CWA DOES INDEED VERIFY. TOUGH TO INCLUDE MENTION OF
WATERSPOUTS THIS FAR OUT IN THE FORECAST BUT WILL BE INTERESTING TO
SEE OUTPUT IN THE NEXT COUPLE DAYS FROM THE NEW EXPERIMENTAL GREAT
LAKES WATERSPOUT FORECAST BASED ON THE SZILAGYI WATERSPOUT INDEX
/SWI/ THAT COMES OUT OF THE INTERNATIONAL CENTRE FOR WATERSPOUT
RESEARCH /ICWR/. IN ADDITION TO WATERSPOUTS...WILL ALSO LIKELY HAVE
INCREASED RISK OF RIP CURRENTS ALONG LK SUPERIOR BEACHES...MAINLY IN
ALGER COUNTY WITH THE EXPECTED NORTHWEST WINDS.
UPPER TROUGH SLOWLY MOVES EAST THROUGH NEXT WEEKEND. THIS PLACES
UPPER LAKES WITHIN ZONE OF SHARP CONFLUENCE AND ASSOCIATED SFC
RIDGING. ECMWF HAS DEFINITELY TRENDED FARTHER EAST WITH TROUGH AND
KEEPS QPF OUT OF UPR MICHIGAN FOR THE WEEKEND. GFS IS SLIGHTLY
FARTHER WEST WITH THE TROUGH AND WOULD KEEP THREAT OF SHRA OVER
EASTERN CWA ON SATURDAY. BASED ON AMPLIFIED PATTERN CANNOT RULE THIS
IDEA OUT AND WILL AT THE LEAST KEEP CONSENSUS SLIGHT CHANCE POPS AND
BUMP UP SKY COVER. SUNDAY INTO MONDAY IS TOUGH TO FIGURE OUT AS
ECMWF CONTINUES TO INDICATE STRONGER SHORTWAVE WITHIN BASE OF TROUGH
LIFTING NORTH AND AFFECTING THE EASTERN PORTIONS OF CWA WITH SOME
SHRA WHILE THE GFS KEEPS ALL THIS TOO FAR TO THE EAST TO AFFECT THE
AREA. NO REAL CONSISTENT SIGNAL FOR EITHER SOLUTION SO HAVE TO KEEP
CONSENSUS POPS AT THIS TIME.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 137 AM EDT TUE SEP 4 2012
EXPECT VLIFR CONDITIONS/FOG THRU SUNRISE AT SAW BEFORE DAYTIME
HEATING BURNS THIS FOG OFF AND BRINGS A RETURN OF VFR CONDITIONS.
DRY LLVL AIR SHOWN ON THE 00Z MPX/INL RAOBS HAS MADE GREATER INROADS
INTO WRN UPR MI...SO LOOK FOR ONLY PTCHY FOG/POSSIBLE MVFR VSBYS AT
THESE LOCATIONS. THE APRCH OF A LO PRES TROF THIS AFTN IN TANDEM
WITH DAYTIME HEATING MAY RESULT IN SOME SHRA/EVEN A TS AT ALL 3
SITES THIS AFTN/EVNG...BUT RELATIVE DRYNESS OF THE LLVLS SHOULD
MAINTAIN VFR CONDITIONS. SOME FOG MAY DVLP AT IWD LATER THIS EVNG
WITH SOME DRYING ALF OVER LINGERNIG LLVL MSTR.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 429 AM EDT MON SEP 3 2012
EXPECT S WINDS UP TO 20 KTS IN ADVANCE OF AN APPROACHING COLD FRONT
TO DIMINISH THIS EVENING AS THE FRONT TENDS TO WEAKEN. LIGHT WINDS WILL
THEN PREVAIL THRU TONIGHT AS A WEAK HI PRES SYSTEM MOVES INTO THE
UPPER GREAT LAKES. A SERIES OF LOW PRESSURE SYSTEMS AND COLD FRONTS
WILL MOVE NEAR LAKE SUPERIOR TUESDAY THROUGH SUNDAY...LEADING TO
PERIODS OF INCREASED WINDS. HOWEVER...AT THIS TIME WINDS ARE EXPECTED
TO REMAIN BELOW 25KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...KC
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS GLASGOW MT
844 PM MDT WED SEP 5 2012
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH FRIDAY...
UPDATED THE FORECAST TO ADJUST TEMPERATURES AND CLOUD COVER FOR THE
OVERNIGHT PERIOD. ALSO INTRODUCED SOME SLIGHT CHANCE POPS ACROSS
THE NORTHERN ZONES FOR THIS EVENING PER THE HRRR MODEL. COLD FRONT
IS MOVING DOWN OUT OF SOUTHERN ALBERTA AND SASKATCHEWAN AND ACROSS
THE NORTH ZONES. RADAR IS PICKING UP SOME LIGHT PRECIP ECHOS ALONG
THE FRONT AND JUST BEHIND IT. ALSO INCREASED THE WIND SPEEDS
BEHIND THE FRONT FOR TOMORROW MORNING. REST OF THE SHORT TERM FORECAST
LOOKS GOOD. RSMITH
PREVIOUS DISCUSSION...COOL FRONT MOVING DOWN THROUGH BC/SK WITH
THE ASSOCIATED WITH A DEEP SURFACE LOW OVER EXTREME NORTHEAST
MANITOBA. CLOUDS AND PRECIP SHIELD ARE CURRENTLY MOVING SOUTHWARD
TOWARDS US BORDER AHEAD OF THE FRONT.
UPPER LEVEL LOW IS ALSO OVER NE MANITOBA WITH A DECENT VORTICITY
MAXIMA COMING ACROSS FROM THE NORTH-CENTRAL PART OF THE STATE
SWINGING TO THE SOUTHEAST PART OF THE STATE.
PRECIPITATION STARTS TO MOVE INTO OUR CWA AFTER 3 AM. THE GFS IS
THE FASTER MODEL OF THE BUNCH AND THE NAM IS THE WETTER MODEL OF
THE BUNCH AND THE SREF IS IN THE MIDDLE OF THE PACK. NO LIGHTNING
SHOWING UP IN CANADA WITH THIS SYSTEM. WE DO HAVE A FEW HOURS OF
INSTABILITY TOMORROW BUT WITH CLOUD COVER IT WILL BE TOUGH TO GET
MUCH THUNDER WITH IT. FORECAST DOES INCLUDE SOME ISOLATED
THUNDERSTORMS BUT MOST RAIN SHOWERS.
AS THE SYSTEM COMES THROUGH...ALL THE MODELS DEPICT SOME BREEZY
CONDITIONS BEHIND THE FRONT TOMORROW SO THE WINDS HAVE BEEN
INCREASED IN OUR WESTERN COUNTIES. THERE COULD BE A BRIEF PERIOD
WHERE FORT PECK LAKE NEEDS A LAKE WIND ADVISORY JUST AFTER SUNRISE
BUT IT DOESN`T LOOK TO LAST LONG. AN ADVISORY NEEDS TO HAVE
SUSTAINED WINDS OF 20 MPH OR HIGHER FOR 3 HOURS OR MORE WILL LEAVE
THIS FOR THE MIDNIGHT SHIFT TO DECIDE IF THE WINDS WILL BE UP
LONGER THAN THAT.
SYSTEM LINGERS A BIT INTO THURSDAY EVENING WITH SOME WIDELY
SCATTERED SHOWERS REMAINING. THEN HIGH PRESSURE PUSHES INTO
NORTHERN MONTANA AND HELPS CLEAR OUT THE CLOUDS AND WINDS DROP
OFF.
AS FOR TEMPERATURES...THE COLD AIR ADVECTION IS PUSHING THROUGH BY
NOON ON THURSDAY. 700 MB TEMPS FALL TO -4C OVER THE AREA WITH 850
MB TEMPS TO AROUND 7C. WITH SKY COVER INSULATING THE AREA THE
FROST THREAT WILL BE HELD AT BAY FOR A BIT LONGER YET. TEMPS
REBOUND BY FRIDAY AFTERNOON THOUGH BRINGING MILD WEATHER INTO THE
WEEKEND AS WELL. FRIDAY SHOULD BE A MILD DAY WITH TEMPERATURES A
3-7 DEGREES WARMER THAN THURSDAY ACROSS THE REGION. FRANSEN
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
THE EXTENDED FORECAST PERIOD BEGINS WITH AN UPPER LEVEL RIDGE OF
HIGH PRESSURE IN CONTROL OVER THE NORTHERN ROCKIES AND ADJACENT
NORTHERN HIGH PLAINS REGIONS. THIS WILL LEAD TO A NICE WARM-UP
THROUGH MONDAY.
BEGINNING ON TUESDAY NEXT WEEK THE TROUGH OVER THE PACIFIC
NORTHWEST BECOMES BETTER ORGANIZED AND DIRECTS MORE MOISTURE AND
FORCING FOR ASCENT OVER NORTHEAST MONTANA. MODEL QPF SOLUTIONS
THAT FAR IN THE EXTENDED ARE NOT SHOWING ENOUGH AGREEMENT TO PAINT
MORE THAN A HINT WITH SILENT POPS FOR NOW. BMICKELSON
PREVIOUS LONG TERM DISCUSSION...THE EXTENDED BEGINS WITH RIDGING
IN PLACE SATURDAY MORNING FOR NORTHEAST MONTANA. THIS CONTINUES
THROUGH MONDAY MORNING WHEN THE GFS AND EC PUSH A TROUGH THROUGH
NORTHEAST MONTANA. LOOK FOR SLOW WARM UP DURING THIS PERIOD.
TUESDAY BOTH THE EC AND GFS PUSH A COLD FRONT THROUGH NORTHEAST
MONTANA. THE EC HAS THE FRONT THROUGH EARLY IN THE MORNING WHERE
THE GFS IS LATER IN THE DAY. STAYED WITH THE EC FASTER FRONTAL
PASSAGE. DID KEEP POPS IN THERE. THE MODELS HAVE BEEN FLIP
FLOPPING FROM RUN TO RUN TO TREND EITHER WAY. PROTON
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL FOR ALL TAF SITES THROUGH MOST OF THE
TAF PERIOD. INCREASING CLOUD COVER APPROACHING FROM THE CANADIAN
ROCKIES WILL CONTINUE TO SPREAD ACROSS NORTHEAST MONTANA THROUGH
THURSDAY. EXPECT NEAR MVFR CEILINGS THURSDAY AFTERNOON WITH THE
MORE LOCALIZED RAIN SHOWERS. GUSTIER WINDS FROM THE NORTH WILL
SETTLE IN TOWARD THE END OF THE TAF CYCLE AS SHOWERS BEGIN TO
DISSIPATE LATER THURSDAY NIGHT. BMICKELSON
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1231 PM CDT TUE SEP 4 2012
.AVIATION...
VFR IS EXPECTED MOST AREAS TODAY AND THROUGH THE OVERNIGHT. ONE
EXCEPTION BEING ACROSS FAR NORTH CENTRAL NEBRASKA...GENERALLY ALONG
AND EAST OF A KBBW TO KONL LINE...WHERE TSTMS ARE POSSIBLE. MODEL
SOUNDINGS INDICATE DRY LOWER LEVELS...THUS HIGH BASED STORMS CAPABLE
OF ERRATIC GUSTY WIND WOULD BE THE EXPECTED STORM THREAT.
OTHERWISE...A FRONT IS PROGGED TO CROSS THE REGION LATER THIS
EVENING...PASSING OVER THE KVTN TERMINAL AROUND 01Z...THEN OVER
KLBF AFTER 05Z. A DISTINCT NORTHERLY WIND SHIFT IS ANTICIPATED ALONG
THE FRONTAL PASSAGE...WITH WIND SPEEDS GUSTING AOA 20KTS POSSIBLE.
&&
PREV DISCUSSION... /ISSUED 345 AM CDT TUE SEP 4 2012/
DISCUSSION...
ONE MORE DAY OF 90S BEFORE A COOL DOWN CAN BE EXPECTED. RIDGE
ACROSS THE SOUTHERN PLAINS WITH SOUTHWEST FLOW IN TRANSITION TO A
MORE ZONAL FLOW AS A TROUGH PUSHES ACROSS THE NORTHERN ROCKIES
AND NORTHERN PLAINS. SURFACE TROUGH ACROSS THE CWA THIS MORNING
WITH VERY DRY AIR...DEW PTS IN THE 30S...WEST OF THE TROUGH...A
KVTN TO KTIF TO KOGA LINE. TO THE EAST OF THE TROUGH DEW PTS IN
THE 50S AND 60S AND A FEW SITES ACROSS CENTRAL NEB STARTING TO
REPORT SOME FOG. COLD FRONT HEADING SOUTH ACROSS THE NORTHERN
ROCKIES.
TROUGH WILL REMAIN NEARLY STATIONARY THIS AFTERNOON ACROSS THE
AREA WITH VERY DRY CONDITIONS AND RH PERCENTAGES NEAR OR BELOW 15
PERCENT TO THE WEST. WINDS ARE MARGINAL...AROUND 15 TO 20 MPH...FOR
RFW CRITERIA...HOWEVER DUE TO DROUGHT AND LOW RH VALUES...WILL
HAVE A RFW FOR MUCH OF NW NEB. AS FOR TEMPS...THE DRY AIR WILL
COMBINE WITH SOME PREFRONTAL COMPRESSIONAL HEATING TO PUSH HIGHS
ONCE AGAIN INTO THE 90S. LATE THIS AFTERNOON ALONG AND EAST OF THE
TROUGH...WHERE BETTER LOW LEVEL MOISTURE...SOME ISOLATED
THUNDERSTORMS ARE POSSIBLE WITH PEAK HEAT...SIMILAR TO YESTERDAY.
BETTER SHEAR/HIGHER CAPE/AND SPC SLIGHT RISK IS EAST OF THE
CWA...HOWEVER EXPECT DEVELOPMENT ALONG TO EAST OF THE
TROUGH...WHICH SHOULD STILL BE OVER THE CWA...AND CANNOT RULE OUT A
STRAY STORM BECOMING STRONG. ONCE THE COLD FRONT MOVES ACROSS THE
AREA THIS EVENING INTO THE OVERNIGHT HOURS...THE CONVECTION WILL
QUICKLY MOVE EAST. DRY AND COOL AIR WILL SPREAD ACROSS THE AREA.
WED HIGHS AROUND 80 ACROSS ALL BUT THE SW...WHICH SHOULD PUSH INTO
THE LOWER 80S. THESE HIGHS ARE FAIRLY CLOSE TO NORMAL FOR THIS
TIME OF YEAR. HOWEVER DEW PTS IN THE 30S TO LOWER 40S WILL
CONTINUE TO CREATE A HIGH DANGER HOWEVER WINDS NOT EXPECTED TO BE
MUCH OVER 10 MPH.
THURSDAY ANOTHER COLD FRONT WILL APPROACH FROM THE NW. AHEAD OF
THE FRONT WINDS BECOME SOUTHERLY AND BRING A RETURN OF WARMER
TEMPERATURES AND POSSIBLY SOME LL MOISTURE. WILL HAVE TO MONITOR
HIGHS AS THE MODELS HAVE TRENDED UP TODAY...WITH THE NAM SEEING AN
INCREASE BACK CLOSE TO 90. HAVE NOT JUMPED TO THIS WARM
YET...HOWEVER IF WE DO WARM TO THIS...NEAR CRITICAL FIRE WEATHER
CONDITIONS WILL BE POSSIBLE AS DEW PTS SLOW TO RISE.
AS THE FRONT PASSES THURSDAY NIGHT INTO FRIDAY MOISTURE WILL
CONTINUE TO BE A LIMITING FACTOR ON SHOWER AND THUNDERSTORM
DEVELOPMENT. HAVE TRENDED DRIER AS RETURN MOISTURE LOOKS TO BE
ONLY TO CURRENT LEVELS...AT BEST...ACCORDING TO LATEST
GUIDANCE...WITH A GOOD POSSIBILITY THIS TREND WILL CONTINUE OVER
THE NEXT FEW FORECAST UPDATES.
FRIDAY INTO SATURDAY WILL BE THE COOLEST OF THE FORECAST PERIOD AS
COOL HIGH PRESSURE SETTLES OVER THE HIGH PLAINS. GUIDANCE AND
FORECAST HAVE HIGHS ONLY IN THE 70S...WITH LOWS IN THE 40S.
BY SUNDAY THE HIGH WILL PUSH TO THE EAST WITH SOUTHERLY FLOW
RETURNING AND BRINGING A SLOW WARMUP INTO THE START OF NEXT WEEK.
STILL NO MOISTURE AND FORECAST REMAINS DRY.
FIRE WEATHER...
HOT DRY AIR WILL SURGE EAST THROUGH WESTERN AND NORTH CENTRAL
NEBRASKA AHEAD OF A STRONG COLD FRONT WHICH WILL MOVE THROUGH
TONIGHT.
CRITICAL FIRE DANGER IS EXPECTED ALONG AND NORTH OF INTERSTATE 80
AND GENERALLY ALONG AND WEST OF HIGHWAY 83. THE 20Z HRRR AND THE
00Z GEM REGIONAL MODELS SUGGEST SIMILAR CONDITIONS WILL DEVELOP
ACROSS SWRN NEB AND PERHAPS INTO AREAS EAST OF HIGHWAY 83. GIVEN
THE DIFFERENCES BETWEEN HRRR AND GEM REGIONAL VERSUS THE NAM AND
ECM WILL HOLD OFF ON AN EXPANSION OF THE RED FLAG WARNING FOR NOW.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING UNTIL 10 PM CDT
/9 PM MDT/ THIS EVENING FOR NEZ204-206-208.
&&
$$
SHORT TERM/EXTENDED...MASEK
AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1212 PM CDT TUE SEP 4 2012
.AVIATION...18Z TAFS FOR KOMA...KLNK AND KOFK. PRIMARY CONCERN
WILL BE CHANCES FOR THUNDERSTORMS AS A FRONT LIFTS THROUGH THE
REGION. BELIEVE BEST CHANCE WOULD AT 21-23Z AT KLNK...AND 23-02Z
AT KOFK AND KOMA. OTHERWISE...VFR CONDITIONS EXPECTED UNTIL THEN
WITH MID BASED CUMULUS CLOUDS EITHER MOVING IN OR DEVELOPING
AROUND 6000-8000 FEET. SECONDARY CONCERN IS THE PLACEMENT OF A
STRONG COLD FRONT SWEEPING FROM NORTHWEST TO SOUTHEAST OVERNIGHT
WITH AN ABRUPT WIND SHIFT TO THE NORTH NORTHWEST AND SUBSTANTIAL
INCREASE IN SPEEDS BEHIND THE FRONT WITH WINDS 15 TO 25 KNOTS.
INITIAL FORECAST PUTS THIS FRONT IN THE KOFK VICINITY BY ABOUT
11Z...AND KLNK/KOMA BY ABOUT 13Z.
DEWALD
&&
.PREV DISCUSSION... /ISSUED 1032 AM CDT TUE SEP 4 2012/
DISCUSSION...
MAIN CONCERN FOR LATE THIS AFTERNOON AND EVENING WILL BE
CONVECTIVE POTENTIAL ALONG/NORTH OF A SURFACE TROUGH THAT EXTENDS
FROM WESTERN NEBRASKA THROUGH SOUTHEAST NEBRASKA. NAM CONTINUES TO
BE THE MOST AGGRESSIVE MODEL IN DEVELOPING CONVECTION BY 21-00Z
ALONG AND NORTH OF I80...THEN CONTINUING THAT THROUGH THE EVENING
BEFORE PUSHING OFF TO THE NORTHEAST. THIS SEEMS REASONABLE GIVE
WEAK ZONAL FLOW ALOFT WITH SUBTLE ALBEIT WEAK HEIGHT FALLS NOTED
ON 12Z OBJECTIVE UPPER AIR ANALYSIS. THIS IS ALSO WITHIN AN AREA
WHERE THE CAP SHOULD BE THE WEAKEST GIVEN 10-11 DEGREES AT H70.
INTERESTING...THE HRRR DOES NOT DEVELOP ANY CONVECTION AT ALL...
AND THE RAP13 HOLDS OFF UNTIL ABOUT 23Z BETWEEN OMAHA AND SIOUX
CITY. MADE MINOR TWEAKS TO THE FORECAST...PULLING POPS JUST A
LITTLE BIT FURTHER SOUTH 21-23Z...OTHERWISE NO OTHER CHANGES MADE.
DEWALD
PREV DISCUSSION... /ISSUED 343 AM CDT TUE SEP 4 2012/
DISCUSSION...
MAIN FORECAST CONCERNS ARE THUNDERSTORM CHANCES THIS
AFTERNOON/EVENING AND AGAIN ON THURSDAY INTO FRIDAY.
WESTERLY UPPER LEVEL FLOW CONTINUES OVERHEAD WITH SEVERAL WEAK
EMBEDDED SHORTWAVES PASSING THROUGH THE FLOW. AT THE SFC...WEAK
AREA OF LOW PRESSURE IS CENTERED OVER CENTRAL SOUTH DAKOTA/CENTRAL
NEBRASKA WITH RICH DEWPOINTS IN THE UPPER 60S TO LOWER 70S
RESIDING OVER MUCH OF EASTERN NEBRASKA AND WESTERN IOWA. THIS MAY
LEAD TO PATCHY FOG FOR THE MORNING COMMUTE AND WILL CONTINUE TO
KEEP AN EYE ON ANY DETERIORATING CONDITIONS THIS MORNING.
AN UPPER LEVEL TROF WILL SWING THROUGH THE CANADIAN PRAIRIE
PROVINCES AND NORTHERN PLAINS TODAY. AHEAD OF THIS...A STRONG COLD
FRONT WILL PUSH SOUTHEAST THROUGH THE PLAINS. AHEAD OF THIS FRONT
THUNDERSTORMS COULD DEVELOP LATE THIS AFTERNOON ALONG THE MOIST
AXIS ACROSS NORTHEAST NEBRASKA AS AFTERNOON HEATING PEAKS. UPPER
LEVEL SUPPORT WILL BE WEAK THROUGHOUT THE LATE AFTERNOON BUT IS
FORECAST TO INCREASE INTO THE EVENING HOURS AHEAD OF A WEAK SHORTWAVE
AHEAD OF THE UPPER TROF. A MAJORITY OF MODEL GUIDANCE SOLUTIONS
DEVELOP AN AREA OF QPF OVER NORTHEAST NEBRASKA...CLOSER TO UPPER
LEVEL FORCING...AROUND 21Z AND SPREAD IT SOUTHEAST WELL AHEAD OF
THE SFC FRONT THRU 06Z. STEEPENING MID LEVEL LAPSE RATES ALONG
WITH MODERATE INSTABILITY AND 0-6KM BULK SHEAR AROUND 40KTS COULD
LEAD TO SOME SEVERE STORMS...MAINLY IN THE NORTHERN CWA. STRONG
SUBSIDENCE IS FORECAST BEHIND THE FRONT SO WILL QUICKLY END POPS
AFTER FROPA WHICH SHOULD BE THRU THE ENTIRE CWA BY 12-15Z WED.
COOLER TEMPERATURES FOLLOW BEHIND THE BOUNDARY WITH HIGHS IN THE
UPPER 70S TO LOWER 80S FOR WEDNESDAY AS HIGH PRESSURE BUILDS INTO
THE CENTRAL PLAINS.
RETURN FLOW SETS UP LATER IN THE DAY THURSDAY SO WL LEAVE MUCH OF
THE DAY DRY WITH POPS RETURNING TO THE FORECAST THURSDAY NIGHT IN
LLVL WARM AIR ADVECTION REGIME. IN ADDITION...ANOTHER UPPER LEVEL
SHORTWAVE WILL BE APPROACHING THE REGION AS A COLD FRONT SLIDES EAST
ACROSS THE FORECAST AREA. NOCTURNAL LOW LEVEL JET MAY SUSTAIN
ACTIVITY THRU THE OVERNIGHT HOURS AS WELL AS INTO FRIDAY MORNING.
A STRENGTHENING UPPER LEVEL TROF MOVING TOWARD THE GREAT LAKES
REGION WILL BRING COOLER TEMPERATURES FOR THE WEEKEND BEFORE THE
TROF CLOSES OFF OVER THE OHIO VALLEY REGION. A LARGE AREA OF SFC
HIGH PRESSURE WILL BE IN PLACE SUNDAY INTO MONDAY. A BIT OF A WARM
UP IS EXPECTED EARLY NEXT WEEK AS AN UPPER LEVEL RIDGE BUILDS
INTO THE CENTRAL PLAINS.
KERN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1032 AM CDT TUE SEP 4 2012
.DISCUSSION...
MAIN CONCERN FOR LATE THIS AFTERNOON AND EVENING WILL BE
CONVECTIVE POTENTIAL ALONG/NORTH OF A SURFACE TROUGH THAT EXTENDS
FROM WESTERN NEBRASKA THROUGH SOUTHEAST NEBRASKA. NAM CONTINUES TO
BE THE MOST AGGRESSIVE MODEL IN DEVELOPING CONVECTION BY 21-00Z
ALONG AND NORTH OF I80...THEN CONTINUING THAT THROUGH THE EVENING
BEFORE PUSHING OFF TO THE NORTHEAST. THIS SEEMS REASONABLE GIVE
WEAK ZONAL FLOW ALOFT WITH SUBTLE ALBEIT WEAK HEIGHT FALLS NOTED
ON 12Z OBJECTIVE UPPER AIR ANALYSIS. THIS IS ALSO WITHIN AN AREA
WHERE THE CAP SHOULD BE THE WEAKEST GIVEN 10-11 DEGREES AT H70.
INTERESTING...THE HRRR DOES NOT DEVELOP ANY CONVECTION AT ALL...
AND THE RAP13 HOLDS OFF UNTIL ABOUT 23Z BETWEEN OMAHA AND SIOUX
CITY. MADE MINOR TWEAKS TO THE FORECAST...PULLING POPS JUST A
LITTLE BIT FURTHER SOUTH 21-23Z...OTHERWISE NO OTHER CHANGES MADE.
DEWALD
&&
.PREV DISCUSSION... /ISSUED 643 AM CDT TUE SEP 4 2012/
AVIATION...
12Z TAFS FOR KOFK...KLNK AND KOMA.
AREAS OF MVFR FOG WILL LIFT BY 15Z THIS MORNING. VSBYS AT KOFK MAY
DROP TO BELOW A MILE FOR A BRIEF TIME AS WELL. THEN SOUTHERLY
WINDS NEAR 10 TO 15KTS WILL PREVAIL WITH SCATTERED CLOUDS NEAR
FL040. THERE IS A CHANCE FOR THUNDERSTORMS OVER ALL OF EASTERN
NEBRASKA AFTER 21Z AS A LOW PRESSURE SYSTEM MOVES INTO THE AREA.
THINKING BEST INSTABILITY WILL FOCUS STORMS NEAR THE MISSOURI
RIVER...TO KOMA WILL HAVE BEST CHANCE FOR STORMS. A COLD FRONT
SHOULD MOVE THROUGH EASTERN NEBRASKA AFTER 06Z...WITH WINDS
TURNING TO NORTHWEST AND THUNDERSTORM CHANCES ENDING BY 10Z ALL
SITES.
DERGAN
PREV DISCUSSION... /ISSUED 343 AM CDT TUE SEP 4 2012/
DISCUSSION...
MAIN FORECAST CONCERNS ARE THUNDERSTORM CHANCES THIS
AFTERNOON/EVENING AND AGAIN ON THURSDAY INTO FRIDAY.
WESTERLY UPPER LEVEL FLOW CONTINUES OVERHEAD WITH SEVERAL WEAK
EMBEDDED SHORTWAVES PASSING THROUGH THE FLOW. AT THE SFC...WEAK
AREA OF LOW PRESSURE IS CENTERED OVER CENTRAL SOUTH DAKOTA/CENTRAL
NEBRASKA WITH RICH DEWPOINTS IN THE UPPER 60S TO LOWER 70S
RESIDING OVER MUCH OF EASTERN NEBRASKA AND WESTERN IOWA. THIS MAY
LEAD TO PATCHY FOG FOR THE MORNING COMMUTE AND WILL CONTINUE TO
KEEP AN EYE ON ANY DETERIORATING CONDITIONS THIS MORNING.
AN UPPER LEVEL TROF WILL SWING THROUGH THE CANADIAN PRAIRIE
PROVINCES AND NORTHERN PLAINS TODAY. AHEAD OF THIS...A STRONG COLD
FRONT WILL PUSH SOUTHEAST THROUGH THE PLAINS. AHEAD OF THIS FRONT
THUNDERSTORMS COULD DEVELOP LATE THIS AFTERNOON ALONG THE MOIST
AXIS ACROSS NORTHEAST NEBRASKA AS AFTERNOON HEATING PEAKS. UPPER
LEVEL SUPPORT WILL BE WEAK THROUGHOUT THE LATE AFTERNOON BUT IS
FORECAST TO INCREASE INTO THE EVENING HOURS AHEAD OF A WEAK SHORTWAVE
AHEAD OF THE UPPER TROF. A MAJORITY OF MODEL GUIDANCE SOLUTIONS
DEVELOP AN AREA OF QPF OVER NORTHEAST NEBRASKA...CLOSER TO UPPER
LEVEL FORCING...AROUND 21Z AND SPREAD IT SOUTHEAST WELL AHEAD OF
THE SFC FRONT THRU 06Z. STEEPENING MID LEVEL LAPSE RATES ALONG
WITH MODERATE INSTABILITY AND 0-6KM BULK SHEAR AROUND 40KTS COULD
LEAD TO SOME SEVERE STORMS...MAINLY IN THE NORTHERN CWA. STRONG
SUBSIDENCE IS FORECAST BEHIND THE FRONT SO WILL QUICKLY END POPS
AFTER FROPA WHICH SHOULD BE THRU THE ENTIRE CWA BY 12-15Z WED.
COOLER TEMPERATURES FOLLOW BEHIND THE BOUNDARY WITH HIGHS IN THE
UPPER 70S TO LOWER 80S FOR WEDNESDAY AS HIGH PRESSURE BUILDS INTO
THE CENTRAL PLAINS.
RETURN FLOW SETS UP LATER IN THE DAY THURSDAY SO WL LEAVE MUCH OF
THE DAY DRY WITH POPS RETURNING TO THE FORECAST THURSDAY NIGHT IN
LLVL WARM AIR ADVECTION REGIME. IN ADDITION...ANOTHER UPPER LEVEL
SHORTWAVE WILL BE APPROACHING THE REGION AS A COLD FRONT SLIDES EAST
ACROSS THE FORECAST AREA. NOCTURNAL LOW LEVEL JET MAY SUSTAIN
ACTIVITY THRU THE OVERNIGHT HOURS AS WELL AS INTO FRIDAY MORNING.
A STRENGTHENING UPPER LEVEL TROF MOVING TOWARD THE GREAT LAKES
REGION WILL BRING COOLER TEMPERATURES FOR THE WEEKEND BEFORE THE
TROF CLOSES OFF OVER THE OHIO VALLEY REGION. A LARGE AREA OF SFC
HIGH PRESSURE WILL BE IN PLACE SUNDAY INTO MONDAY. A BIT OF A WARM
UP IS EXPECTED EARLY NEXT WEEK AS AN UPPER LEVEL RIDGE BUILDS
INTO THE CENTRAL PLAINS.
KERN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
636 AM CDT TUE SEP 4 2012
.UPDATE...
.AVIATION...
VFR IS EXPECTED MOST AREAS TODAY AND TONIGHT.
PATCHY MORNING FOG WILL DISSIPATE ALONG AND EAST OF HIGHWAY 183 BY 14-15Z.
ISOLATED THUNDERSTORMS ARE EXPECTED LATE THIS AFTERNOON THROUGH
EARLY EVENING ALONG AND EAST OF HIGHWAY 83. WINDY CONDITIONS ARE
EXPECTED TONIGHT BEHIND A STRONG COLD FRONT.
&&
.PREV DISCUSSION... /ISSUED 345 AM CDT TUE SEP 4 2012/
DISCUSSION...
ONE MORE DAY OF 90S BEFORE A COOL DOWN CAN BE EXPECTED. RIDGE
ACROSS THE SOUTHERN PLAINS WITH SOUTHWEST FLOW IN TRANSITION TO A
MORE ZONAL FLOW AS A TROUGH PUSHES ACROSS THE NORTHERN ROCKIES
AND NORTHERN PLAINS. SURFACE TROUGH ACROSS THE CWA THIS MORNING
WITH VERY DRY AIR...DEW PTS IN THE 30S...WEST OF THE TROUGH...A
KVTN TO KTIF TO KOGA LINE. TO THE EAST OF THE TROUGH DEW PTS IN
THE 50S AND 60S AND A FEW SITES ACROSS CENTRAL NEB STARTING TO
REPORT SOME FOG. COLD FRONT HEADING SOUTH ACROSS THE NORTHERN
ROCKIES.
TROUGH WILL REMAIN NEARLY STATIONARY THIS AFTERNOON ACROSS THE
AREA WITH VERY DRY CONDITIONS AND RH PERCENTAGES NEAR OR BELOW 15
PERCENT TO THE WEST. WINDS ARE MARGINAL...AROUND 15 TO 20 MPH...FOR
RFW CRITERIA...HOWEVER DUE TO DROUGHT AND LOW RH VALUES...WILL
HAVE A RFW FOR MUCH OF NW NEB. AS FOR TEMPS...THE DRY AIR WILL
COMBINE WITH SOME PREFRONTAL COMPRESSIONAL HEATING TO PUSH HIGHS
ONCE AGAIN INTO THE 90S. LATE THIS AFTERNOON ALONG AND EAST OF THE
TROUGH...WHERE BETTER LOW LEVEL MOISTURE...SOME ISOLATED
THUNDERSTORMS ARE POSSIBLE WITH PEAK HEAT...SIMILAR TO YESTERDAY.
BETTER SHEAR/HIGHER CAPE/AND SPC SLIGHT RISK IS EAST OF THE
CWA...HOWEVER EXPECT DEVELOPMENT ALONG TO EAST OF THE
TROUGH...WHICH SHOULD STILL BE OVER THE CWA...AND CANNOT RULE OUT A
STRAY STORM BECOMING STRONG. ONCE THE COLD FRONT MOVES ACROSS THE
AREA THIS EVENING INTO THE OVERNIGHT HOURS...THE CONVECTION WILL
QUICKLY MOVE EAST. DRY AND COOL AIR WILL SPREAD ACROSS THE AREA.
WED HIGHS AROUND 80 ACROSS ALL BUT THE SW...WHICH SHOULD PUSH INTO
THE LOWER 80S. THESE HIGHS ARE FAIRLY CLOSE TO NORMAL FOR THIS
TIME OF YEAR. HOWEVER DEW PTS IN THE 30S TO LOWER 40S WILL
CONTINUE TO CREATE A HIGH DANGER HOWEVER WINDS NOT EXPECTED TO BE
MUCH OVER 10 MPH.
THURSDAY ANOTHER COLD FRONT WILL APPROACH FROM THE NW. AHEAD OF
THE FRONT WINDS BECOME SOUTHERLY AND BRING A RETURN OF WARMER
TEMPERATURES AND POSSIBLY SOME LL MOISTURE. WILL HAVE TO MONITOR
HIGHS AS THE MODELS HAVE TRENDED UP TODAY...WITH THE NAM SEEING AN
INCREASE BACK CLOSE TO 90. HAVE NOT JUMPED TO THIS WARM
YET...HOWEVER IF WE DO WARM TO THIS...NEAR CRITICAL FIRE WEATHER
CONDITIONS WILL BE POSSIBLE AS DEW PTS SLOW TO RISE.
AS THE FRONT PASSES THURSDAY NIGHT INTO FRIDAY MOISTURE WILL
CONTINUE TO BE A LIMITING FACTOR ON SHOWER AND THUNDERSTORM
DEVELOPMENT. HAVE TRENDED DRIER AS RETURN MOISTURE LOOKS TO BE
ONLY TO CURRENT LEVELS...AT BEST...ACCORDING TO LATEST
GUIDANCE...WITH A GOOD POSSIBILITY THIS TREND WILL CONTINUE OVER
THE NEXT FEW FORECAST UPDATES.
FRIDAY INTO SATURDAY WILL BE THE COOLEST OF THE FORECAST PERIOD AS
COOL HIGH PRESSURE SETTLES OVER THE HIGH PLAINS. GUIDANCE AND
FORECAST HAVE HIGHS ONLY IN THE 70S...WITH LOWS IN THE 40S.
BY SUNDAY THE HIGH WILL PUSH TO THE EAST WITH SOUTHERLY FLOW
RETURNING AND BRINGING A SLOW WARMUP INTO THE START OF NEXT WEEK.
STILL NO MOISTURE AND FORECAST REMAINS DRY.
AVIATION...
VFR IS EXPECTED MOST AREAS TODAY AND TONIGHT.
PATCHY MORNING FOG WILL DEVELOP ALONG AND EAST OF HIGHWAY 183
THROUGH 14Z. ISOLATED THUNDERSTORMS ARE EXPECTED LATE THIS
AFTERNOON AND THIS EVENING ALONG AND EAST OF HIGHWAY 83. WINDY
CONDITIONS ARE EXPECTED TONIGHT BEHIND A STRONG COLD FRONT.
FIRE WEATHER...
HOT DRY AIR WILL SURGE EAST THROUGH WESTERN AND NORTH CENTRAL
NEBRASKA AHEAD OF A STRONG COLD FRONT WHICH WILL MOVE THROUGH
TONIGHT.
CRITICAL FIRE DANGER IS EXPECTED ALONG AND NORTH OF INTERSTATE 80
AND GENERALLY ALONG AND WEST OF HIGHWAY 83. THE 20Z HRRR AND THE
00Z GEM REGIONAL MODELS SUGGEST SIMILAR CONDITIONS WILL DEVELOP
ACROSS SWRN NEB AND PERHAPS INTO AREAS EAST OF HIGHWAY 83. GIVEN
THE DIFFERENCES BETWEEN HRRR AND GEM REGIONAL VERSUS THE NAM AND
ECM WILL HOLD OFF ON AN EXPANSION OF THE RED FLAG WARNING FOR NOW.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING FROM 11 AM CDT
/10 AM MDT/ THIS MORNING TO 10 PM CDT /9 PM MDT/ THIS EVENING FOR
NEZ204-206-208.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
345 AM CDT TUE SEP 4 2012
.DISCUSSION...
ONE MORE DAY OF 90S BEFORE A COOL DOWN CAN BE EXPECTED. RIDGE
ACROSS THE SOUTHERN PLAINS WITH SOUTHWEST FLOW IN TRANSITION TO A
MORE ZONAL FLOW AS A TROUGH PUSHES ACROSS THE NORTHERN ROCKIES
AND NORTHERN PLAINS. SURFACE TROUGH ACROSS THE CWA THIS MORNING
WITH VERY DRY AIR...DEW PTS IN THE 30S...WEST OF THE TROUGH...A
KVTN TO KTIF TO KOGA LINE. TO THE EAST OF THE TROUGH DEW PTS IN
THE 50S AND 60S AND A FEW SITES ACROSS CENTRAL NEB STARTING TO
REPORT SOME FOG. COLD FRONT HEADING SOUTH ACROSS THE NORTHERN
ROCKIES.
TROUGH WILL REMAIN NEARLY STATIONARY THIS AFTERNOON ACROSS THE
AREA WITH VERY DRY CONDITIONS AND RH PERCENTAGES NEAR OR BELOW 15
PERCENT TO THE WEST. WINDS ARE MARGINAL...AROUND 15 TO 20 MPH...FOR
RFW CRITERIA...HOWEVER DUE TO DROUGHT AND LOW RH VALUES...WILL
HAVE A RFW FOR MUCH OF NW NEB. AS FOR TEMPS...THE DRY AIR WILL
COMBINE WITH SOME PREFRONTAL COMPRESSIONAL HEATING TO PUSH HIGHS
ONCE AGAIN INTO THE 90S. LATE THIS AFTERNOON ALONG AND EAST OF THE
TROUGH...WHERE BETTER LOW LEVEL MOISTURE...SOME ISOLATED
THUNDERSTORMS ARE POSSIBLE WITH PEAK HEAT...SIMILAR TO YESTERDAY.
BETTER SHEAR/HIGHER CAPE/AND SPC SLIGHT RISK IS EAST OF THE
CWA...HOWEVER EXPECT DEVELOPMENT ALONG TO EAST OF THE
TROUGH...WHICH SHOULD STILL BE OVER THE CWA...AND CANNOT RULE OUT A
STRAY STORM BECOMING STRONG. ONCE THE COLD FRONT MOVES ACROSS THE
AREA THIS EVENING INTO THE OVERNIGHT HOURS...THE CONVECTION WILL
QUICKLY MOVE EAST. DRY AND COOL AIR WILL SPREAD ACROSS THE AREA.
WED HIGHS AROUND 80 ACROSS ALL BUT THE SW...WHICH SHOULD PUSH INTO
THE LOWER 80S. THESE HIGHS ARE FAIRLY CLOSE TO NORMAL FOR THIS
TIME OF YEAR. HOWEVER DEW PTS IN THE 30S TO LOWER 40S WILL
CONTINUE TO CREATE A HIGH DANGER HOWEVER WINDS NOT EXPECTED TO BE
MUCH OVER 10 MPH.
THURSDAY ANOTHER COLD FRONT WILL APPROACH FROM THE NW. AHEAD OF
THE FRONT WINDS BECOME SOUTHERLY AND BRING A RETURN OF WARMER
TEMPERATURES AND POSSIBLY SOME LL MOISTURE. WILL HAVE TO MONITOR
HIGHS AS THE MODELS HAVE TRENDED UP TODAY...WITH THE NAM SEEING AN
INCREASE BACK CLOSE TO 90. HAVE NOT JUMPED TO THIS WARM
YET...HOWEVER IF WE DO WARM TO THIS...NEAR CRITICAL FIRE WEATHER
CONDITIONS WILL BE POSSIBLE AS DEW PTS SLOW TO RISE.
AS THE FRONT PASSES THURSDAY NIGHT INTO FRIDAY MOISTURE WILL
CONTINUE TO BE A LIMITING FACTOR ON SHOWER AND THUNDERSTORM
DEVELOPMENT. HAVE TRENDED DRIER AS RETURN MOISTURE LOOKS TO BE
ONLY TO CURRENT LEVELS...AT BEST...ACCORDING TO LATEST
GUIDANCE...WITH A GOOD POSSIBILITY THIS TREND WILL CONTINUE OVER
THE NEXT FEW FORECAST UPDATES.
FRIDAY INTO SATURDAY WILL BE THE COOLEST OF THE FORECAST PERIOD AS
COOL HIGH PRESSURE SETTLES OVER THE HIGH PLAINS. GUIDANCE AND
FORECAST HAVE HIGHS ONLY IN THE 70S...WITH LOWS IN THE 40S.
BY SUNDAY THE HIGH WILL PUSH TO THE EAST WITH SOUTHERLY FLOW
RETURNING AND BRINGING A SLOW WARMUP INTO THE START OF NEXT WEEK.
STILL NO MOISTURE AND FORECAST REMAINS DRY.
&&
.AVIATION...
VFR IS EXPECTED MOST AREAS TODAY AND TONIGHT.
PATCHY MORNING FOG WILL DEVELOP ALONG AND EAST OF HIGHWAY 183
THROUGH 14Z. ISOLATED THUNDERSTORMS ARE EXPECTED LATE THIS
AFTERNOON AND THIS EVENING ALONG AND EAST OF HIGHWAY 83. WINDY
CONDITIONS ARE EXPECTED TONIGHT BEHIND A STRONG COLD FRONT.
&&
.FIRE WEATHER...
HOT DRY AIR WILL SURGE EAST THROUGH WESTERN AND NORTH CENTRAL
NEBRASKA AHEAD OF A STRONG COLD FRONT WHICH WILL MOVE THROUGH
TONIGHT.
CRITICAL FIRE DANGER IS EXPECTED ALONG AND NORTH OF INTERSTATE 80
AND GENERALLY ALONG AND WEST OF HIGHWAY 83. THE 20Z HRRR AND THE
00Z GEM REGIONAL MODELS SUGGEST SIMILAR CONDITIONS WILL DEVELOP
ACROSS SWRN NEB AND PERHAPS INTO AREAS EAST OF HIGHWAY 83. GIVEN
THE DIFFERENCES BETWEEN HRRR AND GEM REGIONAL VERSUS THE NAM AND
ECM WILL HOLD OFF ON AN EXPANSION OF THE RED FLAG WARNING FOR NOW.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING FROM 11 AM
CDT /10 AM MDT/ THIS MORNING TO 10 PM CDT /9 PM MDT/ THIS EVENING
FOR NEZ204-206-208.
&&
$$
DISCUSSION...MASEK
AVIATION/FIRE WEATHER...CDC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
253 AM EDT TUE SEP 4 2012
.SYNOPSIS...
UNSETTLED WEATHER WILL PERSIST THROUGH WEDNESDAY AS THE REMNANTS OF
TROPICAL CYCLONE ISAAC SLOWLY WEAKEN ALONG THE CENTRAL AND SOUTHERN
APPALACHIANS.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1005 PM MONDAY...
TONIGHT: FORECAST RATIONALE RELATIVELY UNCHANGED FROM EARLIER
THINKING. ONE WEAKENING BAND OF CONVECTION AND EMBEDDED MCV/S NEAR
KFVX AND KLHZ WILL CONTINUE TO CROSS THE FAR NORTHEAST PIEDMONT AND
NORTHERN COASTAL PLAIN THROUGH MIDNIGHT. HEAVY RAIN WILL BE THE
PRIMARY HAZARD WITH THIS CONVECTION. THE MAIN FOCUS FOR SCATTERED
CONVECTION OVERNIGHT WILL THEN OCCUR OVER THE WESTERN HALF OF THE
RAH CWFA....PARTICULARLY OVER THE WESTERN PIEDMONT...WHERE DEEP
LAYER MOISTURE TRANSPORT AND GLANCING FORCING FOR ASCENT ASSOCIATED
WITH WEAK PERTURBATIONS IN SOUTHWESTERLY FLOW ALOFT -- EVIDENT ON
02Z WV IMAGERY AND RAP ANALYZED VORTICITY FIELDS FROM EASTERN AL TO
THE SC UPSTATE -- ARE FORECAST TO BE MAXIMIZED. PERSISTENCE LOWS
GENERALLY IN THE LOWER 70S...WITH AREAS OF STRATUS AND/OR FOG LATE.
THESE SHOWERS AND ISOLATED STORMS TOO WILL POSE A RISK OF HEAVY
RAIN...BUT THE SCATTERED NATURE AND DIMINISHED INSTABILITY SUGGEST A
MINIMAL THREAT OF FLOODING.
AS OF 340 PM MONDAY...
OVERVIEW:
THE REMNANTS OF TROPICAL CYCLONE ISAAC WILL GET STRETCHED AND
SHEARED APART DURING THE DAY ON TUESDAY...LEAVING BEHIND A WEAK
MID/UPPER LEVEL TROUGHINESS ACROSS THE CAROLINAS.
TUESDAY AND TUESDAY NIGHT:
THE MOIST AIRMASS FEATURING PWATS AT OR ABOVE 2.0" WILL REMAIN IN
PLACE ACROSS THE CAROLINAS ON TUESDAY. THERE REMAINS SOME
QUESTIONS/UNCERTAINTY REGARDING PENDING DEVELOPMENT AND EVOLUTION OF
A SOUTHWARD PROPAGATING MCS TOWARDS THE GULF COAST STATES THAT COULD
AUGMENT/DISTURB MOISTURE CONVERGENCE OVER THE AREA...BUT OVERALL
THINKING IS THAT WE WILL SEE DIURNAL ENHANCEMENT IN CONVECTIVE
COVERAGE TUESDAY AFTERNOON...ESPECIALLY OVER THE WESTERN PIEDMONT
INVOF OF THE BROAD TROUGHINESS AND CONTINUED UPSLOPE REGIME ALONG
THE EASTERN SLOPES. ELSEWHERE...MUCH LIKE TODAY...FORCING WILL BE
MOSTLY CONFINED TO VIA MESOSCALE BOUNDARIES SUCH AS DIFFERENTIAL
HEATING...OUTFLOW OR SEABREEZE. POPS RANGING FROM LIKELY WEST TO
CHANCE POPS EAST.
HIGHS TUESDAY SHOULD BE VERY SIMILAR TO TODAY...DEPENDENT ON HOW
EARLY CONVECTION/RAIN MOVES INTO WESTERN PORTIONS OF THE FORECAST
AREA. HIGHS IN THE LOWER TO MID 80S WEST TO NEAR 90 CENTRAL AND
EASTERN AREAS. LOWS 69 TO 73.
SEVERE THREAT...ORGANIZED SEVERE WEATHER APPEARS UNLIKELY
THIS AFTERNOON AND AGAIN TOMORROW WITH INSTABILITY TEMPERED BY CLOUD
COVER AND WEAK MID-LEVEL LAPSE RATES. HOWEVER...AN ISOLATED SEVERE
THREAT CANNOT BE RULED OUT WHERE MESOSCALE PROCESSES LOCALLY ENHANCE
LOW/MID LEVEL SHEAR AND ASCENT. THE MAIN CONCERN WILL BE FROM
HEAVY RAINFALL AND FLASH FLOODING...PRIMARILY IN THE WESTERN
PIEDMONT WHERE A SLOW MOVING NORTH-SOUTH ORIENTED LINE OF CONVECTION
COULD PERSIST FOR SEVERAL HOURS.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 240 AM TUESDAY...
LOCALLY HEAVY RAIN WEDNESDAY AFTERNOON AND EVENING...
THE COMBINATION OF THE RESIDUAL MID-UPPER LEVEL TROUGH AND A WEAK
COLD FRONT WILL COMBINE WITH DEEP BOUNDARY LAYER MOISTURE AND
SURFACE HEATING TO BRING ANOTHER GOOD CHANCE OF MAINLY AFTERNOON AND
EVENING SHOWERS AND THUNDERSTORMS ON WEDNESDAY. QPF ON THE ORDER OF
0.25 TO 0.50 WILL BE FORECAST... WHICH IS AN AREAL AVERAGE FOR THE
REGION. HOWEVER... LOCALLY 1-2 INCHES OF RAIN ARE EXPECTED WHICH MAY
LEAD AGAIN TO MAINLY URBAN AND SMALL STREAM FLOODING. FORECAST
SOUNDINGS INDICATE MORE LOW STRATUS TO START THE DAY BEFORE BURNING
OFF TO PARTLY SUNNY SKIES BY MID MORNING. HIGHS SHOULD TOP OUT A FEW
DEGREES ABOVE THE EARLY SEP AVERAGE. EXPECT MID TO UPPER 80S OVER
THE PIEDMONT WITH AROUND 90 ACROSS THE SANDHILLS AND COASTAL PLAIN.
EXPECT THE CONVECTION TO BECOME MORE ISOLATED OVERNIGHT WITH
ADDITIONAL STRATUS LATE. LOWS AGAIN WEDNESDAY NIGHT WILL BE IN THE
LOWER 70S AS THE DEW POINTS WILL CONTINUE VERY OPPRESSIVE.
THE WEAK COLD FRONT IS FORECAST TO STALL OVER OUR AREA THURSDAY INTO
THURSDAY NIGHT. WE WILL MAINTAIN A GOOD CHANCE OF MAINLY AFTERNOON
AND EVENING SHOWERS AND THUNDERSTORMS THURSDAY. HIGHS ONCE AGAIN
SHOULD BE IN THE MID TO UPPER 80S NW AND AROUND 90 SE.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 250 AM TUESDAY...
MORE OPPRESSIVE HUMIDITY ALONG WITH SHOWERS AND THUNDERSTORMS
EXPECTED INTO EARLY NEXT WEEK.
ANOTHER STRONG MID-UPPER LEVEL TROUGH/CUT OFF LOW EXPECTED TO
DEVELOP OVER THE OHIO/TENNESSEE VALLEY REGION THIS WEEKEND AND EARLY
NEXT WEEK. JUST HOW FAR SOUTH THE UPPER LOW DEVELOPS WILL DETERMINE
THE COVERAGE AND AMOUNTS OF RAIN FOR OUR REGION SAT-MON. THE LATEST
TRENDS SUPPORT A DEEPER AND MORE CUT-OFF H5 LOW AS FAR SOUTH AS THE
SOUTHERN APPALACHIANS SUN-MON. THIS WOULD SUGGEST ANOTHER VERY WET
PERIOD FOR THE CENTRAL AND SOUTHERN APPALACHIANS EAST ACROSS NC/VA
WITH LOCALLY HEAVY RAIN. HOWEVER... THERE CONTINUED TO BE ENOUGH
SPREAD IN THE MODEL SOLUTIONS TO INFER ONLY LOW TO MEDIUM CONFIDENCE
IN THE DETAILS THIS FAR OUT. THEREFORE... WE WILL MAINTAIN
INCREASING CHANCES OF SHOWERS/STORMS SAT-SUN. THE WARM AND MOIST
PATTERN MAY PERSIST INTO EARLY NEXT WEEK BEFORE THE UPPER TROUGH/LOW
PULL OUT TO THE NE TUE-WED.
FRIDAY... WE WILL CARRY 20-30 POP AS THE LOW LEVEL BOUNDARY WILL BE
IN THE REGION (MORE LIKELY STALLING OVER THE EASTERN PIEDMONT OR
COASTAL PLAIN). PARTLY SUNNY OTHERWISE WITH HIGHS IN THE MID 80S NW
TO AROUND 90 SE.
SAT-MON... WE WILL CARRY 40-50 POP WITH MAINLY AFTERNOON AND EVENING
SHOWERS AND STORMS. DEPENDING ON THE EVOLUTION OF THE UPPER
TROUGH... LOCALLY HEAVY RAIN MAY BE A THREAT AGAIN. HIGHS WILL BE
MOSTLY IN THE 80S. LOWS IN THE 70-73 RANGE...EXCEPT UPPER 60S NW.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 115 AM TUESDAY...
24-HR TAF PERIOD:
INT/GSO:
THE BEST CHANCE FOR ADVERSE AVIATION CONDITIONS TODAY WILL BE IN
WESTERN PORTIONS OF THE STATE (INT/GSO TERMINALS) WHERE LOW-LEVEL
MOISTURE AND UPPER LEVEL FORCING ASSOCIATED WITH THE REMNANTS OF TC
ISAAC WILL BE MAXIMIZED. EXPECT IFR/LIFR STRATUS AND SCATTERED
CONVECTION AT THE INT/GSO TERMINALS BETWEEN 06-15Z...WITH CEILINGS
IMPROVING TO MVFR BY EARLY/MID AFTERNOON (~18Z) AND SCATTERED/
PERIODIC CONVECTION THROUGH THE REMAINDER OF THE TAF PERIOD.
RDU:
EXPECT A CHANCE FOR ISOLATED CONVECTION AND IFR/LIFR CEILINGS OR
VISBYS BETWEEN 06-12Z AT THE RDU TERMINAL...WITH ANY IFR/LIFR
CEILINGS IMPROVING TO MVFR AND EVENTUALLY VFR BY 15-18Z. PERIODIC
CONVECTION WILL REMAIN POSSIBLE THROUGHOUT THE TAF PERIOD...THOUGH
THE BEST OVERALL CHANCES ARE EXPECTED FURTHER WEST AT THE INT/GSO
TERMINALS AS MENTIONED ABOVE.
FAY/RWI:
DRIER LOW-LEVEL (2500-5000 FT AGL) CONDITIONS WILL BE PRESENT OVER
EASTERN PORTIONS OF THE AREA TODAY...AND IT WOULD APPEAR THAT
SUB-VFR VISBYS ASSOCIATED WITH FOG ARE MORE LIKELY THAN SUB-VFR
CEILINGS BETWEEN 06-12Z THIS MORNING. LOCALLY DENSE FOG AND IFR/LIFR
VISBYS CANNOT BE RULED OUT IN THE 10-12Z TIME FRAME WHERE CLOUD
COVER IS THINNER AND WINDS GO CALM PRIOR TO SUNRISE. ANY FOG WOULD
BE EXPECTED TO LIFT TO VFR BY 12-14Z. ISOLD CONVECTION WILL BE
POSSIBLE AT THE FAY/RWI TERMINALS THROUGHOUT THE TAF PERIOD...THOUGH
UNCERTAINTY IN THE TIMING AND COVERAGE OF CONVECTION IS GREATER AT
THESE SITES THAN POINTS FURTHER WEST.
WEDNESDAY-SUNDAY:
GIVEN LITTLE CHANGE IN THE OVERALL PATTERN WED/WED NIGHT...
ANTICIPATE SIMILAR CONDITIONS TO TODAY AND MONDAY...CHARACTERIZED BY
MORNING FOG/STRATUS AND PERIODIC SHOWERS/STORMS...WITH THE BEST
CHANCE AND GREATEST COVERAGE DURING THE AFTERNOON AND EVENING HOURS.
DRIER/VFR CONDITIONS WILL BE MORE LIKELY THU/FRI AS THE REMNANTS OF
TC ISAAC WASH OUT AND A DRIER AIRMASS BUILDS TOWARD THE AREA FROM
THE WEST. HOWEVER...ADVERSE AVIATION CONDITIONS ARE EXPECTED TO
RETURN OVER THE WEEKEND AS UN UNSEASONABLY DEEP UPPER LEVEL TROUGH
DIGS INTO THE TN VALLEY AND DEEP SOUTH. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM....MWS/CBL
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
118 AM EDT TUE SEP 4 2012
.SYNOPSIS...
UNSETTLED WEATHER WILL PERSIST THROUGH WEDNESDAY AS THE REMNANTS OF
TROPICAL CYCLONE ISAAC SLOWLY WEAKEN ALONG THE CENTRAL AND SOUTHERN
APPALACHIANS.
&&
.NEAR TERM /THROUGH TUESDAY NIGHT/...
AS OF 1005 PM MONDAY...
TONIGHT: FORECAST RATIONALE RELATIVELY UNCHANGED FROM EARLIER
THINKING. ONE WEAKENING BAND OF CONVECTION AND EMBEDDED MCV/S NEAR
KFVX AND KLHZ WILL CONTINUE TO CROSS THE FAR NORTHEAST PIEDMONT AND
NORTHERN COASTAL PLAIN THROUGH MIDNIGHT. HEAVY RAIN WILL BE THE
PRIMARY HAZARD WITH THIS CONVECTION. THE MAIN FOCUS FOR SCATTERED
CONVECTION OVERNIGHT WILL THEN OCCUR OVER THE WESTERN HALF OF THE
RAH CWFA....PARTICULARLY OVER THE WESTERN PIEDMONT...WHERE DEEP
LAYER MOISTURE TRANSPORT AND GLANCING FORCING FOR ASCENT ASSOCIATED
WITH WEAK PERTURBATIONS IN SOUTHWESTERLY FLOW ALOFT -- EVIDENT ON
02Z WV IMAGERY AND RAP ANALYZED VORTICITY FIELDS FROM EASTERN AL TO
THE SC UPSTATE -- ARE FORECAST TO BE MAXIMIZED. PERSISTENCE LOWS
GENERALLY IN THE LOWER 70S...WITH AREAS OF STRATUS AND/OR FOG LATE.
THESE SHOWERS AND ISOLATED STORMS TOO WILL POSE A RISK OF HEAVY
RAIN...BUT THE SCATTERED NATURE AND DIMINISHED INSTABILITY SUGGEST A
MINIMAL THREAT OF FLOODING.
AS OF 340 PM MONDAY...
OVERVIEW:
THE REMNANTS OF TROPICAL CYCLONE ISAAC WILL GET STRETCHED AND
SHEARED APART DURING THE DAY ON TUESDAY...LEAVING BEHIND A WEAK
MID/UPPER LEVEL TROUGHINESS ACROSS THE CAROLINAS.
TUESDAY AND TUESDAY NIGHT:
THE MOIST AIRMASS FEATURING PWATS AT OR ABOVE 2.0" WILL REMAIN IN
PLACE ACROSS THE CAROLINAS ON TUESDAY. THERE REMAINS SOME
QUESTIONS/UNCERTAINTY REGARDING PENDING DEVELOPMENT AND EVOLUTION OF
A SOUTHWARD PROPAGATING MCS TOWARDS THE GULF COAST STATES THAT COULD
AUGMENT/DISTURB MOISTURE CONVERGENCE OVER THE AREA...BUT OVERALL
THINKING IS THAT WE WILL SEE DIURNAL ENHANCEMENT IN CONVECTIVE
COVERAGE TUESDAY AFTERNOON...ESPECIALLY OVER THE WESTERN PIEDMONT
INVOF OF THE BROAD TROUGHINESS AND CONTINUED UPSLOPE REGIME ALONG
THE EASTERN SLOPES. ELSEWHERE...MUCH LIKE TODAY...FORCING WILL BE
MOSTLY CONFINED TO VIA MESOSCALE BOUNDARIES SUCH AS DIFFERENTIAL
HEATING...OUTFLOW OR SEABREEZE. POPS RANGING FROM LIKELY WEST TO
CHANCE POPS EAST.
HIGHS TUESDAY SHOULD BE VERY SIMILAR TO TODAY...DEPENDENT ON HOW
EARLY CONVECTION/RAIN MOVES INTO WESTERN PORTIONS OF THE FORECAST
AREA. HIGHS IN THE LOWER TO MID 80S WEST TO NEAR 90 CENTRAL AND
EASTERN AREAS. LOWS 69 TO 73.
SEVERE THREAT...ORGANIZED SEVERE WEATHER APPEARS UNLIKELY
THIS AFTERNOON AND AGAIN TOMORROW WITH INSTABILITY TEMPERED BY CLOUD
COVER AND WEAK MID-LEVEL LAPSE RATES. HOWEVER...AN ISOLATED SEVERE
THREAT CANNOT BE RULED OUT WHERE MESOSCALE PROCESSES LOCALLY ENHANCE
LOW/MID LEVEL SHEAR AND ASCENT. THE MAIN CONCERN WILL BE FROM
HEAVY RAINFALL AND FLASH FLOODING...PRIMARILY IN THE WESTERN
PIEDMONT WHERE A SLOW MOVING NORTH-SOUTH ORIENTED LINE OF CONVECTION
COULD PERSIST FOR SEVERAL HOURS.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 PM MONDAY...
UNSETTLED WEATHER WILL LIKELY PERSIST ACROSS CENTRAL NC THROUGH THE
SHORT TERM PERIOD AS WEAK TROUGHING ALOFT REMAINS OVER THE AREA. AT
THE SURFACE...A WEAK BOUNDARY WILL APPROACH THE AREA LATE WEDNESDAY
INTO THURSDAY. ALL OF THIS COMBINED WITH AMPLE MOISTURE (PWAT VALUES
EXCEEDING 2 INCHES) AND A MODERATELY UNSTABLE AIR MASS WILL RESULT
IN SCATTERED SHOWERS AND THUNDERSTORMS...MAINLY DURING THE AFTERNOON
AND EVENING HOURS. AT THIS TIME...AM EXPECTING THE BEST COVERAGE TO
BE ACROSS THE WEST ON WEDNESDAY AS THERE WILL BE SLIGHTLY DRIER AIR
ACROSS THE EAST AND THEN THE BEST FOCUS SHOULD SHIFT TO THE EAST FOR
THURSDAY AS SLIGHTLY DRIER AIR MOVES IN BEHIND THE AFOREMENTIONED
SURFACE BOUNDARY. THE MAIN THREAT IS EXPECTED TO BE HEAVY RAIN THAT
COULD LEAD TO SOME FLOODING...ESPECIALLY IN URBAN AREAS. HIGH TEMPS
WILL BE NEAR NORMAL...GENERALLY IN THE MID/UPPER 80S...WITH
OVERNIGHT LOWS RUNNING SLIGHTLY ABOVE NORMAL...GENERALLY IN THE
UPPER 60S TO LOWER 70S.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 300 PM MONDAY...
AN UNSETTLED WEATHER PATTERN IS EXPECTED TO CONTINUE THROUGH MUCH OF
THE LONG TERM PERIOD. FOR FRIDAY...THE BROAD TROUGH ALOFT WILL STILL
BE OVER THE AREA...WHILE AT THE SURFACE A WEAK SURFACE BOUNDARY (SEE
ABOVE SHORT TERM DISCUSSION) WILL LIKELY BE WASHING OUT OVER THE
AREA. NEVERTHELESS...WITH MOISTURE CONTENT STILL EXPECTED TO BE HIGH
ACROSS THE REGION...AM EXPECTING ANOTHER GOOD CHANCE OF SHOWERS AND
THUNDERSTORMS. BY THE WEEKEND...A SHORT WAVE COMING OUT OF CENTRAL
CANADA WILL RESULT IN A TROUGH AMPLIFYING AS IT MOVES ACROSS THE
MIDWEST ON SATURDAY AND TOWARDS THE EAST COAST BY SUNDAY. AS THIS
RATHER DEEP TROUGH AND ITS ASSOCIATED SURFACE FRONT APPROACHES THE
REGION...THIS SHOULD RESULT IN A PROLONGED PERIOD OF GOOD PRECIP
CHANCES THROUGH AT LEAST THE END OF THE WEEKEND. AS CAN BE EXPECTED
THIS FAR OUT...THERE ARE TIMING AND STRENGTH DIFFERENCES....BUT WILL
BEGIN TO TAPER POPS DOWNWARD LATE SUNDAY AND INTO EARLY NEXT WEEK.
THERE ARE STILL FAIRLY STRONG INDICATIONS THAT COOLER AND DRIER AIR
SHOULD ARRIVE SOMETIME EARLY NEXT WEEK AS A RATHER DEEP TROUGH/CUT
OFF LOW DEVELOPS. OVERALL...TEMPS WILL BE NEAR NORMAL EARLY ON IN
THE PERIOD BEFORE TRENDING BELOW NORMAL AS INCREASED PRECIP CHANCES
AND THE DEEP TROUGH/ASSOCIATED SURFACE FRONT APPROACH AND MOVE
THROUGH THE REGION.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 115 AM TUESDAY...
24-HR TAF PERIOD:
INT/GSO:
THE BEST CHANCE FOR ADVERSE AVIATION CONDITIONS TODAY WILL BE IN
WESTERN PORTIONS OF THE STATE (INT/GSO TERMINALS) WHERE LOW-LEVEL
MOISTURE AND UPPER LEVEL FORCING ASSOCIATED WITH THE REMNANTS OF TC
ISAAC WILL BE MAXIMIZED. EXPECT IFR/LIFR STRATUS AND SCATTERED
CONVECTION AT THE INT/GSO TERMINALS BETWEEN 06-15Z...WITH CEILINGS
IMPROVING TO MVFR BY EARLY/MID AFTERNOON (~18Z) AND SCATTERED/
PERIODIC CONVECTION THROUGH THE REMAINDER OF THE TAF PERIOD.
RDU:
EXPECT A CHANCE FOR ISOLATED CONVECTION AND IFR/LIFR CEILINGS OR
VISBYS BETWEEN 06-12Z AT THE RDU TERMINAL...WITH ANY IFR/LIFR
CEILINGS IMPROVING TO MVFR AND EVENTUALLY VFR BY 15-18Z. PERIODIC
CONVECTION WILL REMAIN POSSIBLE THROUGHOUT THE TAF PERIOD...THOUGH
THE BEST OVERALL CHANCES ARE EXPECTED FURTHER WEST AT THE INT/GSO
TERMINALS AS MENTIONED ABOVE.
FAY/RWI:
DRIER LOW-LEVEL (2500-5000 FT AGL) CONDITIONS WILL BE PRESENT OVER
EASTERN PORTIONS OF THE AREA TODAY...AND IT WOULD APPEAR THAT
SUB-VFR VISBYS ASSOCIATED WITH FOG ARE MORE LIKELY THAN SUB-VFR
CEILINGS BETWEEN 06-12Z THIS MORNING. LOCALLY DENSE FOG AND IFR/LIFR
VISBYS CANNOT BE RULED OUT IN THE 10-12Z TIME FRAME WHERE CLOUD
COVER IS THINNER AND WINDS GO CALM PRIOR TO SUNRISE. ANY FOG WOULD
BE EXPECTED TO LIFT TO VFR BY 12-14Z. ISOLD CONVECTION WILL BE
POSSIBLE AT THE FAY/RWI TERMINALS THROUGHOUT THE TAF PERIOD...THOUGH
UNCERTAINTY IN THE TIMING AND COVERAGE OF CONVECTION IS GREATER AT
THESE SITES THAN POINTS FURTHER WEST.
WEDNESDAY-SUNDAY:
GIVEN LITTLE CHANGE IN THE OVERALL PATTERN WED/WED NIGHT...
ANTICIPATE SIMILAR CONDITIONS TO TODAY AND MONDAY...CHARACTERIZED BY
MORNING FOG/STRATUS AND PERIODIC SHOWERS/STORMS...WITH THE BEST
CHANCE AND GREATEST COVERAGE DURING THE AFTERNOON AND EVENING HOURS.
DRIER/VFR CONDITIONS WILL BE MORE LIKELY THU/FRI AS THE REMNANTS OF
TC ISAAC WASH OUT AND A DRIER AIRMASS BUILDS TOWARD THE AREA FROM
THE WEST. HOWEVER...ADVERSE AVIATION CONDITIONS ARE EXPECTED TO
RETURN OVER THE WEEKEND AS UN UNSEASONABLY DEEP UPPER LEVEL TROUGH
DIGS INTO THE TN VALLEY AND DEEP SOUTH. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM....MWS/CBL
SHORT TERM...KRR
LONG TERM...KRR
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
801 PM EDT WED SEP 5 2012
.SYNOPSIS...
A WEAK DISTURBANCE AND COLD FRONT MAY BRING UNSETTLED WEATHER
ACROSS THE AREA LATE TONIGHT AND THURSDAY MORNING. HIGH PRESSURE
WILL BRING FAIR WEATHER THURSDAY AFTERNOON THROUGH FRIDAY. A
STRONGER STORM SYSTEM AND COLD FRONT WILL BRING PRECIPITATION TO
OUR AREA BY FRIDAY NIGHT WITH COOLER TEMPERATURES ARRIVING THIS
WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
ONGOING CONVECTION ACROSS THE SOUTHEASTERN ZONES ON THE NORTHERN
EDGE OF A SQUALL LINE WILL EXIT OUR AREA BY LATE THIS EVENING.
GRADUAL CLEARING WILL OCCUR BEHIND THIS PRECIPITATION.
THERE IS A LOT OF UNCERTAINTY LATE TONIGHT REGARDING THE
POTENTIAL DEVELOPMENT OF CONVECTION TO OUR NORTHWEST...ASSOCIATED
WITH A COLD FRONT. THE HI-RES MODELS DEVELOP CONVECTION ACROSS
NORTHERN ILLINOIS AND LAKE MICHIGAN AND PUSHES IT INTO OUR AREA
AFTER MIDNIGHT. THE NAM NO LONGER FORECASTS THIS CONVECTION.
HOWEVER THIS MODEL ALSO DID NOT CAPTURE THE CURRENT CONVECTION IN
ITS INITIALIZATION. THE GLOBAL MODELS ARE VERY MEAGER...IF ANY
WITH THE OVERNIGHT CONVECTION. WITH THE VARYING MODEL SOLUTIONS
AND THE CURRENT NON-EXISTENCE OF THE ACTUAL STORMS...HAVE PULLED
BACK POPS TO CHANCE FOR TONIGHT. HAVE ALSO SLOWED DOWN THE ARRIVAL
OF PRECIPITATION BY SEVERAL HOURS...WHICH IS MORE IN LINE WITH THE
LATEST RAP RUN.
IF ENOUGH CLEARING OCCURS LATER THIS EVENING THEN WE MAY SEE
ANOTHER ROUND OF FOG DEVELOP AFTER MIDNIGHT. THIS ALSO IS
UNCERTAIN DUE TO THE ABOVE MENTIONED SCENARIO. THEREFORE HAVE KEPT
THE MENTION OF FOG OUT OF THE ZONES FOR NOW.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
ANY REMNANT PRECIPITATION FROM OVERNIGHT CONVECTION SHOULD COME TO
AN END QUICKLY AFTER SUNRISE THURSDAY. A COLD FRONT WILL PUSH
ACROSS THE FORECAST AREA ON THURSDAY WITH WEAK SURFACE RIDGING
BUILDING IN BEHIND IT. THIS WILL RESULT IN TEMPERATURES IN THE LOW
80S NORTH OF THE FRONT ACROSS THE NORTH TO THE UPPER 80S ACROSS
THE SOUTH...CLOSER TO THE FRONT. THE FRONT WILL THEN STALL OUT
JUST SOUTH OF THE OHIO RIVER LATE THURSDAY. A CONTINUED STRONGER
TEMPERATURE GRADIENT ACROSS THE FORECAST AREA WILL GO INTO
THURSDAY NIGHT WITH THE COLD FRONT NEARBY. EXPECT TEMPERATURES
RANGING FROM THE UPPER 50S ACROSS THE NORTHWEST TO THE MIDDLE 60S
ACROSS THE SOUTH.
THE RIDGE WILL KEEP FAIR WEATHER IN PLACE THROUGH FRIDAY.
INCREASING CLOUD COVER AHEAD OF AN APPROACHING STORM SYSTEM WILL
KEEP TEMPERATURES IN THE LOW TO MID 80S ACROSS THE AREA FRIDAY
AFTERNOON.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
MODELS ARE IN GOOD AGREEMENT NOW WITH A MORE PROGRESSIVE SOLUTION IN
REGARD TO THE DEVELOPING MID/UPPER LEVEL TROUGH THAT WILL AFFECT THE
REGION THIS WEEKEND. AS A RESULT...HAVE SPED UP THE POPS SOMEWHAT
FOR FRIDAY NIGHT AS AN ASSOCIATED COLD FRONT APPROACHES FROM THE
WEST. EXPECT THE BEST CHANCE FOR PCPN TO BE LATE FRIDAY NIGHT INTO
SATURDAY MORNING...WITH PCPN CHANCES THEN TAPERING OFF FROM WEST TO
EAST THROUGH THE AFTERNOON HOURS ON SATURDAY. THERE ARE SOME MINOR
TIMING DIFFERENCES WITH THE FRONT AND THIS COULD HAVE AN AFFECT ON
TEMPERATURES FRIDAY NIGHT AND POSSIBLY INTO SATURDAY. THE 12Z NAM IS
SOMEWHAT SLOWER THAN THE 12Z GFS AND ECMWF. GIVEN THE MORE
PROGRESSIVE NATURE...HAVE TRENDED TOWARD THE FASTER SOLUTIONS...BUT
THEY MAY STILL BE SLOW ENOUGH TO KEEP TEMPS UP A BIT MORE ACROSS OUR
SOUTHEAST AT LEAST THROUGH FRIDAY NIGHT.
A WEAK SECONDARY SHORT WAVE WILL PIVOT DOWN ACROSS THE GREAT LAKES
SATURDAY NIGHT INTO SUNDAY. WITH A LITTLE BIT OF DIURNAL HELP...WE
COULD SEE SOME SPOTTY SHOWERS POP UP SUNDAY AFTERNOON...PRIMARILY
ACROSS THE NORTHERN PORTIONS OF OUR FA. HIGH PRESSURE WILL THEN
BUILD INTO THE REGION THROUGH THE MIDDLE PART OF NEXT WEEK. MONDAY
NIGHT MAY END UP BEING OUR COOLEST NIGHT WITH THE SURFACE HIGH CLOSE
TO BEING OVERHEAD. WE SHOULD THEN SEE A GRADUAL WARM UP TUESDAY INTO
WEDNESDAY AS WE GET INTO SOME RETURN FLOW ON THE BACK SIDE OF THE
SURFACE HIGH.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
WESTERLY MID LEVEL FLOW WITH SEVERAL SHORTWAVES TRACKING THRU THE
GREAT LAKES WILL BRING CHANCES FOR THUNDERSTORMS. MOST CONVECTION
HAD PUSHED SE OF TAF SITES BY WED EVENING. MAY SEE ISOLD LIGHT
RAIN AT KCMH AND KLCK TIL 02Z. ALTHOUGH NAM/WRF MODEL SOLUTIONS
INDICATING THAT ADDITIONAL THUNDERTORM DEVELOPMENT WILL OCCUR TO
OUR NW AND THEN DROP SE INTO ILNS FA OVERNIGHT...GFS INDICATES
BETTER CHANCE OF CONVECTION DURING DAY THU WITH PASSAGE OF COLD
FRONT. NO DEVELOPMENT OF CONVECTION EVIDENT EARLY THIS EVENING AS
MODELS FORECAST. DUE TO UNCERTAINTY HAVE LIMITED MENTION OF
CONVECTION TO VCSH ON THU MRNG INTO AFTN...MAINLY WITH THE COLD
FRONT. SHOULD SEE SOME CLEARING TONIGHT AND LIGHT SWRLY WIND FLOW.
WITH ABUNDANT LOW LEVEL MOISTURE...HAVE INCLUDED THE MENTION OF
FOG REDEVELOPMENT TONIGHT WITH MVFR VSBY RESTRICTION AT KCVG/KILN
AND KLCK AND IFR AT KLUK. AFTER FRONTAL PASSAGE THU...EXPECT VFR
CONDITIONS.
.OUTLOOK...MVFR CEILINGS AND VISIBILITIES POSSIBLE SATURDAY AND
SATURDAY NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...LATTO
NEAR TERM...LATTO
SHORT TERM...LATTO
LONG TERM...JGL
AVIATION...PARKER
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
752 PM EDT WED SEP 5 2012
.SYNOPSIS...
DYING MCS MOVING INTO NORTHEAST KY AND EXTREME SOUTHERN WV THIS
EVENING. COLD FRONT ARRIVES THURSDAY FOLLOWED BY AN UPPER LEVEL
LOW AND SURFACE COLD FRONT FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
UPDATED POPS/WX PER LATEST RADAR IMAGES SHOWING DIURNAL CONVECTION
DEVELOPING ACROSS THE SOUTHERN THIRD OF WV. SO...WENT MORE DETERMINISTIC
WITH HIGH LIKELIES. ONLY THE OLD RUN FROM THE HRRR DEPICTED THIS
ACTIVITY WITH THE REST OF MODELS OVERDOING THE REST OF THE AREA
WHICH REMAINS CLEAR SKIES AND DRY.
THE NAM SHOWS FORCING IN THE MID LEVEL OMEGA REACHING THE SOUTHERN
COAL FIELDS LATE THIS EVENING BY 00Z THU...BUT BELIEVE THAT IS
ASSOCIATED WITH THE APPROACHING MCS FEATURE INTO NORTHEAST
KY...WELL AHEAD OF A COLD FRONT.
PREVIOUS DISCUSSION BELOW...
ALMOST LIKE A MID SUMMER PATTERN WHERE WEAK FLOW IS DOMINATED BY
MESOSCALE INFLUENCES...BEFORE COLD FRONT APPROACHES FROM THE WEST
LATER THURSDAY. THE HI RES MODELS HAVE DONE A POOR JOB
INITIALIZING MCS OVER INDIANA THIS MORNING...AND APPARENTLY TOO
AGGRESSIVE IN PUSHING WEAK FRONT AND DEEPER MOISTURE OUT OF AREA
THIS AFTERNOON. THE NAM HAS DONE A BETTER JOB THAN THE GFS...AND
WILL USE NAM DETAILS. STILL...WILL HAVE TO BE MORE AGGRESSIVE THAN
MODELS EARLY IN TONIGHT PERIOD FOR EFFECTS OF THE INDIANA MCS AS
IT MOVES EAST AND WEAKENS. WILL INTRODUCE LOW POPS OVER SOUTHWEST
THIRD OF AREA EARLY TONIGHT TO ACCOUNT FOR POSSIBLE MCS BEFORE IN
SINKS SOUTH OUT OF THE AREA LATE TONIGHT. ALSO...WILL DOWN PLAY
NAM AGGRESSIVENESS ON ANOTHER MCS DROPPING SOUTHEAST OUT OF
NORTHERN INDIANA LATER TONIGHT...UNTIL WE SEE EFFECTS OF PRECEDING
MCS. IN SHORT...HAVE SOME SORT OF LOW POPS OVER THE WESTERN AND
SOUTHERN PORTIONS OVERNIGHT. TEMPS AGAIN OVERNIGHT WILL BE HIGHER
THAN GUIDANCE WITH THE HIGH MOISTURE...CLOSER TO MET NUMBERS.
FOR THURSDAY...COLD FRONT COMES ACROSS FROM THE NORTHWEST...MANLY
AFFECTING THE AREA IN THE AFTERNOON. AGAIN...UNCERTAINTY ON HOW
VIGOROUS THIS FRONT AND CONVECTION WILL BE PROMPTS A CHANCE POP WITH
THE FRONT. TEMPS WILL BE ON THE HIGH SIDE OF GUIDANCE...HITTING 90
MANY LOCATIONS.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/...
PRECIP WILL COME TO AN END FROM WEST TO EAST THURSDAY NIGHT AS WEAK
FRONT PULLS AWAY/DISSIPATES. NAM LINGERS MOISTURE INTO
FRIDAY...WHILE GFS IS A BIT FASTER MOVING IT OUT. HAVE SLIGHT CHANCE
POPS IN THE MOUNTAINS FRIDAY AFTERNOON TO ACCOUNT FOR ANY ISOLATED
DIURNAL CONVECTION THAT MAY DEVELOP.
ONLY A SHORT BREAK BEFORE THE NEXT SYSTEM MOVES IN FOR THE WEEKEND.
MODELS AND ENSEMBLES HAVE CONTINUED TRENDING TOWARDS THE IDEA OF AN
OPEN TROUGH...AND KEEP IT FAIRLY PROGRESSIVE. WITH THIS IN
MIND...SPED UP ENTIRE SYSTEM A BIT...WITH SLIGHT CHANCE POPS
ENTERING SE OHIO LATE FRIDAY EVENING AND INTO THE WV MOUNTAINS
OVERNIGHT. THEN HAVE LIKELY POPS INTO SE OHIO BY SATURDAY MORNING
AND THE WV MOUNTAINS EARLY SATURDAY AFTERNOON. KEPT THE HIGHEST POPS
ALONG AND IN FRONT OF THE SURFACE COLD FRONT...WHICH SHOULD CROSS
THE OHIO RIVER 18Z-20Z AND EXIT EAST OF FORECAST AREA SATURDAY
NIGHT.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
MADE WHOLESALE CHANGES TO THE LONG TERM FORECAST AS MODELS COMING
INTO BETTER AGREEMENT THAN YESTERDAY...NOW SHOWING OPEN WAVE
SWINGING THROUGH OVER THE WEEKEND...AND A THING OF THE PAST AS WE
HEAD INTO THE WORK WEEK. LINGER CHANCE AND SLIGHT CHANCE POPS
THROUGH SUNDAY...MOVING OUT SUNDAY NIGHT AS THE UPPER TROUGH MOVES
EAST AND OUT TO SEA. THIS WILL PROVIDE A MAINLY DRY FORECAST FOR THE
REST OF THE LONG TERM. DID NOT INCLUDE ANY POPS FOR THE WORK WEEK AT
THIS TIME DUE TO LACKING MOISTURE...BUT WITH NORTHWEST FLOW IT MAY
BE POSSIBLE TO GET A LITTLE SHORTWAVE RIPPLE THAT COULD POP A SHOWER
OR TWO AT SOME POINT. TEMPERATURES WILL START OFF BELOW NORMAL ON
MONDAY...WITH A GRADUAL WARMING TREND TO NEAR NORMAL BY MID TO LATE
WEEK AS UPPER RIDGE MOVES INTO SOUTHERN PLAINS.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
MVFR AND GUSTY WINDS IN TEMPO FOR CRW...HTS...AND BKW AS DIURNAL
CONVECTION...COMBINED WITH STORMS ASSOCIATED WITH A DYING MCS
APPROACHES FROM THE SOUTHWEST. THE NAM HAS MID LEVEL OMEGA ACROSS
THE SOUTHERN THIRD OF WV 00-03Z TIME FRAME. THE REST OF THE AREA
WILL BE COVERED BY HIGH LEVEL CLOUDS ASSOCIATED WITH THE MCS.
EXPECT AN AREA OF LIGHT RAIN ENTERING SOUTHEAST OH EARLY TONIGHT
BEFORE DISSIPATES BY MIDNIGHT.
TRICKY FORECAST IN TERMS OF FOG OR LOW STRATUS FORMATION OVER
SITES. KEPT MVFR 2SM VISIBILITIES AT CRW...BKW...AND CKB WHERE LOW
STRATUS WILL BE MORE FAVORABLE. IFR AT EKN WILL BE MORE LIKELY IN
DENSE FOG DUE TO PROTECTED RIVER VALLEY TOPOGRAPHY.
ANOTHER MCS MAY DEVELOP AND TRACK SOUTHEAST FROM NORTHERN INDIANA
TO AFFECT NORTHWEST PORTIONS OF AREA AFTER 08Z. ALL THIS OVERNIGHT
ACTIVITY FORECAST IS WITH LOW CONFIDENCE...AND WILL GO OPTIMISTIC
FOR MAINLY MID CLOUDS WITH THESE SYSTEMS. HOWEVER...FOG WILL FROM
LATER TONIGHT AFTER 06Z...ESPECIALLY EAST PORTIONS WITH LESSER
CLOUDS. WILL GO WITH MVFR TO LOCALLY IFR FOG UNTIL 12Z.
AFTER 12Z...VFR CEILINGS WITH INCREASING CHANCE FOR JUST AFTER THIS
PERIOD AS COLD FRONT APPROACHES.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z FRIDAY...
FORECAST CONFIDENCE: LOW.
ALTERNATE SCENARIOS: TIMING AND DENSITY OF FOG AND/OR LOW STRATUS
MAY VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE THU 09/06/12
UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11
EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07
CRW CONSISTENCY H H H H H H H H L L L M
HTS CONSISTENCY H H H H H H H H H H H M
BKW CONSISTENCY M H H H H H H H H H H L
EKN CONSISTENCY H H H H H H M L L L L L
PKB CONSISTENCY H H H H H H H H L L L M
CKB CONSISTENCY H H H H H H H H L L L H
AFTER 00Z FRIDAY...
IFR FOG EXPECTED AT SOME TERMINALS 09 TO 12Z THURSDAY. BRIEF IFR
POSSIBLE IN THUNDERSTORMS SATURDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...ARJ/JMV/MZ
NEAR TERM...JMV
SHORT TERM...MZ
LONG TERM...MZ
AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
720 PM EDT WED SEP 5 2012
.SYNOPSIS...
A WEAK DISTURBANCE AND COLD FRONT MAY BRING UNSETTLED WEATHER
ACROSS THE AREA LATE TONIGHT AND THURSDAY MORNING. HIGH PRESSURE
WILL BRING FAIR WEATHER THURSDAY AFTERNOON THROUGH FRIDAY. A
STRONGER STORM SYSTEM AND COLD FRONT WILL BRING PRECIPITATION TO
OUR AREA BY FRIDAY NIGHT WITH COOLER TEMPERATURES ARRIVING THIS
WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
ONGOING CONVECTION ACROSS THE SOUTHEASTERN ZONES ON THE NORTHERN
EDGE OF A SQUALL LINE WILL EXIT OUR AREA BY LATE THIS EVENING.
GRADUAL CLEARING WILL OCCUR BEHIND THIS PRECIPITATION.
THERE IS A LOT OF UNCERTAINTY LATE TONIGHT REGARDING THE
POTENTIAL DEVELOPMENT OF CONVECTION TO OUR NORTHWEST...ASSOCIATED
WITH A COLD FRONT. THE HI-RES MODELS DEVELOP CONVECTION ACROSS
NORTHERN ILLINOIS AND LAKE MICHIGAN AND PUSHES IT INTO OUR AREA
AFTER MIDNIGHT. THE NAM NO LONGER FORECASTS THIS CONVECTION.
HOWEVER THIS MODEL ALSO DID NOT CAPTURE THE CURRENT CONVECTION IN
ITS INITIALIZATION. THE GLOBAL MODELS ARE VERY MEAGER...IF ANY
WITH THE OVERNIGHT CONVECTION. WITH THE VARYING MODEL SOLUTIONS
AND THE CURRENT NON-EXISTENCE OF THE ACTUAL STORMS...HAVE PULLED
BACK POPS TO CHANCE FOR TONIGHT. HAVE ALSO SLOWED DOWN THE ARRIVAL
OF PRECIPITATION BY SEVERAL HOURS...WHICH IS MORE IN LINE WITH THE
LATEST RAP RUN.
IF ENOUGH CLEARING OCCURS LATER THIS EVENING THEN WE MAY SEE
ANOTHER ROUND OF FOG DEVELOP AFTER MIDNIGHT. THIS ALSO IS
UNCERTAIN DUE TO THE ABOVE MENTIONED SCENARIO. THEREFORE HAVE KEPT
THE MENTION OF FOG OUT OF THE ZONES FOR NOW.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
ANY REMNANT PRECIPITATION FROM OVERNIGHT CONVECTION SHOULD COME TO
AN END QUICKLY AFTER SUNRISE THURSDAY. A COLD FRONT WILL PUSH
ACROSS THE FORECAST AREA ON THURSDAY WITH WEAK SURFACE RIDGING
BUILDING IN BEHIND IT. THIS WILL RESULT IN TEMPERATURES IN THE LOW
80S NORTH OF THE FRONT ACROSS THE NORTH TO THE UPPER 80S ACROSS
THE SOUTH...CLOSER TO THE FRONT. THE FRONT WILL THEN STALL OUT
JUST SOUTH OF THE OHIO RIVER LATE THURSDAY. A CONTINUED STRONGER
TEMPERATURE GRADIENT ACROSS THE FORECAST AREA WILL GO INTO
THURSDAY NIGHT WITH THE COLD FRONT NEARBY. EXPECT TEMPERATURES
RANGING FROM THE UPPER 50S ACROSS THE NORTHWEST TO THE MIDDLE 60S
ACROSS THE SOUTH.
THE RIDGE WILL KEEP FAIR WEATHER IN PLACE THROUGH FRIDAY.
INCREASING CLOUD COVER AHEAD OF AN APPROACHING STORM SYSTEM WILL
KEEP TEMPERATURES IN THE LOW TO MID 80S ACROSS THE AREA FRIDAY
AFTERNOON.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
MODELS ARE IN GOOD AGREEMENT NOW WITH A MORE PROGRESSIVE SOLUTION IN
REGARD TO THE DEVELOPING MID/UPPER LEVEL TROUGH THAT WILL AFFECT THE
REGION THIS WEEKEND. AS A RESULT...HAVE SPED UP THE POPS SOMEWHAT
FOR FRIDAY NIGHT AS AN ASSOCIATED COLD FRONT APPROACHES FROM THE
WEST. EXPECT THE BEST CHANCE FOR PCPN TO BE LATE FRIDAY NIGHT INTO
SATURDAY MORNING...WITH PCPN CHANCES THEN TAPERING OFF FROM WEST TO
EAST THROUGH THE AFTERNOON HOURS ON SATURDAY. THERE ARE SOME MINOR
TIMING DIFFERENCES WITH THE FRONT AND THIS COULD HAVE AN AFFECT ON
TEMPERATURES FRIDAY NIGHT AND POSSIBLY INTO SATURDAY. THE 12Z NAM IS
SOMEWHAT SLOWER THAN THE 12Z GFS AND ECMWF. GIVEN THE MORE
PROGRESSIVE NATURE...HAVE TRENDED TOWARD THE FASTER SOLUTIONS...BUT
THEY MAY STILL BE SLOW ENOUGH TO KEEP TEMPS UP A BIT MORE ACROSS OUR
SOUTHEAST AT LEAST THROUGH FRIDAY NIGHT.
A WEAK SECONDARY SHORT WAVE WILL PIVOT DOWN ACROSS THE GREAT LAKES
SATURDAY NIGHT INTO SUNDAY. WITH A LITTLE BIT OF DIURNAL HELP...WE
COULD SEE SOME SPOTTY SHOWERS POP UP SUNDAY AFTERNOON...PRIMARILY
ACROSS THE NORTHERN PORTIONS OF OUR FA. HIGH PRESSURE WILL THEN
BUILD INTO THE REGION THROUGH THE MIDDLE PART OF NEXT WEEK. MONDAY
NIGHT MAY END UP BEING OUR COOLEST NIGHT WITH THE SURFACE HIGH CLOSE
TO BEING OVERHEAD. WE SHOULD THEN SEE A GRADUAL WARM UP TUESDAY INTO
WEDNESDAY AS WE GET INTO SOME RETURN FLOW ON THE BACK SIDE OF THE
SURFACE HIGH.
&&
.AVIATION /23Z WEDNESDAY THROUGH MONDAY/...
WESTERLY MID LEVEL FLOW WITH SEVERAL SHORTWAVES TRACKING THRU THE
GREAT LAKES WILL BRING CHANCES FOR THUNDERSTORMS. CONVECTION
PUSHING E ACRS INDIANA IN MODERATELY UNSTBL AIRMASS EXPECTED TO
PUSH INTO WESTERN OHIO DURG AFTN AND WEAKEN SOME. HAVE TEMPO GROUP
FOR THUNDER AT WESTERN TAF SITES BUT LIMITED MENTION TO VCSH AT
KCMH/KLCK. EXPECT VFR CONDITIONS IN THE WAKE OF THIS CONVECTION
EARLY THIS EVENING. 12A NAM/WRF MODEL SOLNS INDICATING THAT
ADDITIONAL THUNDERSTORM DEVELOPMENT WILL OCCUR TO OUR NW AND THEN
DROP SE INTO ILNS FA OVERNIGHT. DUE TO UNCERTAINTY HAVE LIMITED
MENTION OF CONVECTION TO VCSH ACRS THE WEST. WITH PARTIAL CLEARING...
LIGHT SWRLY WIND FLOW AND ABUNDANT LOW LEVEL MSTR...HAVE INCLUDED
THE MENTION OF FOG REDEVELOP TONIGHT. HAVE MVFR VSBY RESTRICTION
AT KCVG/KILN AND KLCK AND IFR AT KLUK. LIGHT SW FLOW OFF WARMER
CITIES MAY LIMIT FOG AT KDAY AND KCMH. SO HAVE NOT MENTIONED FOG
AT THESE SITES AT THIS TIME. ADDITIONAL THUNDERSTORM DEVELOPMENT
POSSIBLE THURSDAY AFTN WITH THE PASSAGE OF A COLD FRONT. HAVE
LIMITED MENTION TO VCSH LATE IN THE TAF PERIOD.
.OUTLOOK...MVFR CEILINGS AND VISIBILITIES POSSIBLE SATURDAY AND
SATURDAY NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...LATTO
NEAR TERM...LATTO
SHORT TERM...LATTO
LONG TERM...JGL
AVIATION...AR
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1032 PM EDT WED SEP 5 2012
.SYNOPSIS...
DEEP TROPICAL MOISTURE CURRENTLY OVER THE REGION WILL BEGIN TO
PROGRESSIVELY LESSENING THURSDAY INTO FRIDAY. A STRONG COLD FRONT
WILL MOVE OVER THE CAROLINAS THIS WEEKEND FOLLOWED BY HIGH PRESSURE
THAT WILL PROVIDE COOLER AND DRYER WEATHER INTO THE FIRST OF NEXT
WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
830 PM EDT UPDATE...NO MAJOR CHANGES NEEDED TO THE GOING FCST. POPS
STILL LOOK GOOD OVER THE NEXT COUPLE HRS...BUT PROBABLY WILL BUMP UP
THE WRN NC MTN ZONES WITH THE OVERNIGHT UPDATE AS THE ACTIVE S/W
APPROACHES THE CWFA FROM THE NW.
530 PM EDT UPDATE...MADE LOWERING CHANGES TO THE POPS/QPF BASED ON
RADAR TRENDS WV IMAGERY AND WRF/ARW OUTPUT. VERY WEAK FORCING ACROSS
THE NRN ZONES AND ACTUAL SUBSIDENCE SOUTH ACROSS THE UPSTATE AND NE
GA HAVE PRECLUDED A SIGFNT CONVECTIVE THREAT IN STRENGTH AND
SPATIALLY THIS EVENING FOR AREAS OUTSIDE THE CENT/NRN NC MTNS AS
WELL AS AREAS SOUTH OF I40. MADE COSMETIC CHANGES TO THE SKY GRIDS
AND MINOR TWEAKS TO TEMPS/TDS...MAINLY ACROSS THE NC MTNS.
THE LATEST WATER VAPOR IMAGERY SHOWS DRIER MID LEVEL AIR SPREADING
ACROSS THE FORECAST AREA SOUTH OF INTERSTATE 40. THE MID LEVEL FLOW
IS QUITE WEAK OVER THE UPSTATE...NE GA AND FAR SRN NC AS A SPUR OF
DEEP LAYER RIDGING HAS PUSHED INTO THE FA FROM THE WEST...FINALLY
DISPLACING THE WEAK...MOIST TROUGH THAT HAD BEEN OVER THE REGION FOR
THE PAST SEVERAL DAYS. THE RAP BRINGS A WEAK SHORT WAVE ACROSS
WESTERN NC THIS EVENING. LLVL CONVERGENCE IS INCREASING OVER THE NC
MTNS AND FOOTHILLS AHEAD OF THE WAVE. THE MODELS ARE SPLIT ON
HOW FAR SOUTHEAST THIS CONVECTION GETS. THE GFS KEEPS IT OVER THE
MTNS AND FOOTHILLS...WHILE THE RAP AND NAM PUSH IT INTO THE NRN
SUBURBS OF CHARLOTTE. WITH THE FINGER OF DRIER AIR PUSHING INTO THE
SRN PIEDMONT I/VE GONE WITH A FORECAST THAT KEEPS THE BEST
CONVECTIVE CHANCES OVER THE MTNS AND FOOTHILLS WITH LOWER POPS ALONG
AND SOUTH OF I-85 AND BACK ACROSS THE SW NC MTNS. THIS IS NOT TO SAY
THAT STORMS WON/T PUSH INTO CHARLOTTE LATER THIS EVENING AS THE
ATMOSPHERE IS NOT CAPPED AND IS MODERATELY UNSTABLE. HOWEVER...THIS
DOES NOT LOOK LIKE THE MOST PROBABLE SOLUTION ATTM.
PATCHY DENSE VALLEY FOG IS EXPECTED OVER THE MTNS TONIGHT. ACROSS
THE FOOTHILLS AND PIEDMONT CONSIDERABLY LESS LOW CLOUD COVER IS
ANTICIPATED OWNING TO A MORE WESTERLY COMPONENT TO THE LLVL WIND
FIELD.
A SHORT WAVE CURRENTLY OVER CENTRAL MISSOURI IS EXPECTED TO CROSS
THE FORECAST AREA DURING THE AFTERNOON HOURS ON THURSDAY. THE DEEP
LAYER RH IS CONSIDERABLY HIGHER ON THU THAN TODAY ALONG AND AHEAD OF
THIS WAVE. BY 21 UTC THE FEATURE IS EXPECTED TO BE OVER THE I-77
CORRIDOR AND IT WILL MOVE EAT OF CHARLOTTE BY THE EARLY EVENING. THE
NAM AND GFS BOTH DEVELOP PCPN BY LATE MORNING AHEAD OF THE SHORT
WAVE. THE NAM HAS PCPN ENDING WITH WEAKLY DIVERGENT LLVL FLOW OVER
MOST OF THE FA DEVELOPING BETWEEN 21-00 UTC. THE WAY IT APPEARS
NOW...A BAND OF SHRA AND A FEW TSTMS WILL DEVELOP DEVELOP OVER THE
FOOTHILLS BY LATE MORNING...OR THEY MAY MOVE INTO THE MTNS AS A
REMNANT OF A WEAKENING MCS. THE CONVECTION WILL MOVE ACROSS THE REST
OF THE FOOTHILLS FROM EARLY TO MID AFTN AND EXIT TO THE EAST BY 6 OR
7 PM. THE SHEAR IS WEAK AND CONVECTION ISN/T EXPECTED TO BE HIGHLY
ORGANIZED AND MOST OF THE STORMS SHOULD BE SUB-SEVERE. THIS IS
GENERALLY SUPPORTED BY THE 12 UTC 4KM SPC WRF AS WELL. FOR NOW I/LL
CAP POPS ARE 40 PERCENT...WITH POPS FALLING OFF QUICKLY TOWARD
SUNSET.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 2 PM EDT WEDNESDAY...THE CONSENSUS OF THE MODEL GUIDANCE
MAINTAINS THAT THE PLUME OF DEEPER MOISTURE WILL HAVE SHIFTED
EASTWARD TO THE COASTAL PLAIN. IN THE WAKE OF A WEAK UPPER WAVE...
THE ENVIRONMENT SHOULD BE LESS FAVORABLE FOR DEEP CONVECTION. THE
CHANCE FOR SHOWERS AND STORMS SHOULD DROP IN THE EARLY EVENING AS
THE FORCING AND MOISTURE MOVE OFF TO THE EAST...TO THE POINT WHERE
THE FCST IS DRY EAST OF THE MTNS FROM 03Z ONWARD. THERE COULD BE A
FEW LINGERING SHOWERS OVER THE MTNS UNTIL LATE EVENING.
FRIDAY LOOKS LIKE A RELATIVELY QUIET TRANSITION DAY WHILE WE WAIT
FOR THE FORCING AND MOISTURE TO RELOAD. A STRONG SHORT WAVE OVER THE
UPPER MS VALLEY WILL DIG AN UPPER TROF DOWN OVER THE UPPER MIDWEST
AND GREAT LAKES THROUGH THE DAY...WHICH WILL GRADUALLY TURN THE FLOW
ALOFT MORE SW. UPPER FORCING WILL BE MINIMAL. THERE SHOULD BE ENOUGH
LOW LEVEL MOISTURE AND BUOYANCY TO SUPPORT SCATTERED SHOWERS AND
STORMS DEVELOPING OVER THE HIGHER TERRAIN WITH DIFFERENTIAL
HEATING...WITH SOME OF THE STORMS MOVING OUT OVER THE FOOTHILLS AND
PIEDMONT IN THE AFTERNOON AND EARLY EVENING. THE STORMS EAST OF THE
BLUE RIDGE WILL DIE OFF WITH SUNSET...BUT WILL KEEP THE CHANCE OF
PRECIP GOING OVERNIGHT ON THE W SIDE OF THE MTNS IN CASE SOME
ACTIVITY MOVES IN FROM THE WEST AHEAD OF THE NEXT FRONT.
THE UPPER TROF CONTINUES TO DIG OVER THE MIDWEST/OH VALLEY ON
SATURDAY AS THE WAVE DROPS SOUTHEASTWARD. DEEP MOISTURE MOVES IN
AHEAD OF THE WAVE TO BE ACTED UPON BY IMPROVED UPPER FORCING AS WE
WORK THROUGH THE DAY. THE OPERATIONAL RUNS FROM ALL THREE MODELS ARE
IN FAIRLY GOOD AGREEMENT WITH THE TIMING OF THE MAIN VORT AXIS
REACHING THE GREAT VALLEY LATE IN THE DAY. THE NEW GFS SWEEPS THE
UPPER TROF AXIS ACROSS THE WESTERN CAROLINAS OVERNIGHT WHILE THE 00Z
RUN PUSHES IT THROUGH SUNDAY MORNING. EITHER WAY...BOTH MODELS
SUGGEST AN EARLIER TIMING OF THE MAIN FRONTAL PRECIP BAND. WILL
LIMIT THE PRECIP TO THE CHANCE RANGE FOR THE TIME BEING BUT WILL
PROBABLY NEED A LIKELY POP FOR AT LEAST THE MTNS...BUT IT IS A
MATTER OF WHICH PERIOD TO FOCUS ON...SATURDAY AFTERNOON OR SATURDAY
NIGHT. WILL NOT RULE OUT SOME SEVERE STORMS IF THE FRONT WILL MOVE
THROUGH EARLY ENOUGH. AT THIS POINT...THINK MOST OF THE PRECIP WILL
HAVE MOVED EAST OF THE FCST AREA BY SUNRISE ON SUNDAY...WHICH AGREES
WITH THE HPC POSITION OF THE MAIN FRONT ON THE COAST AT THAT TIME.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 1130 AM EDT WEDNESDAY...AFTER DEALING WITH A SEMI-TROPICAL AIR
MASS FOR THE LAST TWO WEEKS...IT APPEARS AS THOUGH WE ARE IN FOR A
PERIOD OF SPECTACULAR EARLY AUTUMN-LIKE WEATHER EARLY NEXT WEEK. BUT
FIRST...WE HAVE TO GET A FRONT THROUGH THE CAROLINAS EARLY ON
SUNDAY. THE GFS MOVES THE MAIN SHORT WAVE LOBE ACROSS THE WESTERN
CAROLINAS EARLY SUNDAY MORNING WHILE THE ECMWF HAS THIS FEATURE
CROSSING SUNDAY AFTERNOON. THE TIMING IS FASTER THAN PREVIOUSLY
INDICATED...WITH THE MAIN SFC FRONT POTENTIALLY MOVING ACROSS THE
AREA SATURDAY NIGHT. WILL BACK OFF TO A SLIGHT CHANCE ACROSS THE
REGION ON SUNDAY AS A FEW SHOWERS COULD BE TRIGGERED BY A SECONDARY
FRONT. EITHER WAY...THERE IS A STRONG INDICATION THAT THE PRECIP
WILL BE LONG GONE BY SUNSET SUNDAY...SO THE PRECIP CHANCES ARE
ELIMINATED ALTOGETHER AFTER 00Z MONDAY.
THE UPPER TROF AXIS WILL REACH THE EASTERN SEABOARD BY MONDAY
MORNING AND MOVE SLOWLY OFFSHORE THROUGH MIDWEEK...WHILE AN UPPER
ANTICYCLONE REMAINS PARKED OVER THE SRN PLAINS. THE RESULTING UPPER
RIDGE TO OUR NW WILL BRING DRY HIGH PRESSURE BUILDING IN SUNDAY
NIGHT AND MONDAY. ONCE ESTABLISHED...THIS SURFACE HIGH WILL DOMINATE
OUR WEATHER AS IT MOVES SLOWLY PAST TO THE NORTH THROUGH WEDNESDAY.
THIS SHOULD BRING MOSTLY CLEAR SKY...DRY AIR...HIGH TEMPS IN THE
MID/UPPER 70S AND LOW TEMPS IN THE MID/UPPER 50S. THUS...MONDAY AND
TUESDAY WILL FEEL MORE LIKE LATE SEPTEMBER OR EARLY OCTOBER. THE AIR
MASS SHOULD START TO MODIFY A BIT BY WEDNESDAY.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
AT KCLT...A VAST AREA OF DEEP SUBSIDENCE WILL PERSIST ACROSS THE
TERMINAL THIS EVENING AND INTO THE OVERNIGHT. THIS HAS PREVENTED
MUCH IF ANY PCPN OR CLOUDS...LET ALONE CONVECTION AROUND THE AREA.
BELIEVE THIS WILL BE MAINTAINED THROUGH THE OVERNIGHT TO A HIGH
DEGREE. THERE WILL BE SOME APPROACHING MLVL ENERGY AND MOISTURE
OVERNIGHT...BUT THIS WILL HAVE TO MAKE IT OVER THE MTNS AND THROUGH
THE AFOREMENTIONED SUBSIDENCE ZONE. SO...DONT ANTICIPATE A SIGFNT
STORM/PCPN THREAT OVERNIGHT. THERE WILL BE ENOUGH MOISTURE TRAPPED
BENEATH THE INVERSION TO ALLOW STCU TO DEVELOP BEFORE DAYBREAK AND
ALL GUIDANCE POINTS TOWARD A MVFR DECK MOST LIKELY PERSISTING TIL
15Z. THE AFTERNOON CONVECTIVE THREAT REMAINS A REAL POSSIBILITY. THE
GREAT VALLEY S/W WILL BE CROSSING THE PIEDMONT NEAR MAX HEATING SO A
PROB390 TS WITH LIMITING VSBY -SHRA IS EXPECTED AFT 18Z.
ELSEWHERE...ONGOING ISOL/SCT CONVECTION WILL PERSIST ACROSS THE
NW/RN ZONES TONIGHT AND INTO THE EARLY MORNING HRS. ENOUGH SO...THAT
VCTS WAS INCLUDED AT KAVL AND KHKY TIL 03Z. THE MTNS COULD
EXPERIENCE A PROLONGED PERIOD OF SCT PRECIP OVERNIGHT WITH AN
APPROACHING S/W AND AN AMENDMENT MAY BE NEEDED AROUND MIDNIGHT.
WITH THE PRECIP MAINLY ACROSS THE HIGHER TERRAIN TODAY...THE NC MTN
VALLEYS AND FOOTHILLS SHOULD HAVE THE BEST SHOT AT IFR MORNING
FG...PERISTING THROUGH 15Z OR SO. AT THE SC UPSTATE TERMINALS...MVFR
TO POSSIBLY IFR STCU WILL BE THE FLIGHT RESTRICTION CONCERN THROUGH
MID MORNING. SCT CONVECTION WILL BEGIN IN THE MTNS RATHER
EARLY...AROUND 16Z...AND SHIFT EAST OVER THE EASTERN TERMINALS
THROUGH THE AFTERNOON.
OUTLOOK...GRADUAL DRYING FROM THE WEST IS EXPECTED ON THURSDAY
AFTERNOON...WITH DEEPER DRYING ON FRIDAY. A COLD FRONT WILL APPROACH THE
REGION FROM THE NORTHWEST ON SATURDAY AND MOVE EAST OF THE AREA ON
SUNDAY.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PM
NEAR TERM...MCAVOY/SBK
SHORT TERM...PM
LONG TERM...PM
AVIATION...SBK
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
827 PM EDT WED SEP 5 2012
.SYNOPSIS...
DEEP TROPICAL MOISTURE CURRENTLY OVER THE REGION WILL BEGIN TO
PROGRESSIVELY LESSENING THURSDAY INTO FRIDAY. A STRONG COLD FRONT
WILL MOVE OVER THE CAROLINAS THIS WEEKEND FOLLOWED BY HIGH PRESSURE
THAT WILL PROVIDE COOLER AND DRYER WEATHER INTO THE FIRST OF NEXT
WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
830 PM EDT UPDATE...NO MAJOR CHANGES NEEDED TO THE GOING FCST. POPS
STILL LOOK GOOD OVER THE NEXT COUPLE HRS...BUT PROBABLY WILL BUMP UP
THE WRN NC MTN ZONES WITH THE OVERNIGHT UPDATE AS AN ACTIVE S/W
APPROACHES THE CWFA FROM THE NW.
530 PM EDT UPDATE...MADE LOWERING CHANGES TO THE POPS/QPF BASED ON
RADAR TRENDS WV IMAGERY AND WRF/ARW OUTPUT. VERY WEAK FORCING ACROSS
THE NRN ZONES AND ACTUAL SUBSIDENCE SOUTH ACROSS THE UPSTATE AND NE
GA HAVE PRECLUDED A SIGFNT CONVECTIVE THREAT IN STRENGTH AND
SPATIALLY THIS EVENING FOR AREAS OUTSIDE THE CENT/NRN NC MTNS AS
WELL AS AREAS SOUTH OF I40. MADE COSMETIC CHANGES TO THE SKY GRIDS
AND MINOR TWEAKS TO TEMPS/TDS...MAINLY ACROSS THE NC MTNS.
THE LATEST WATER VAPOR IMAGERY SHOWS DRIER MID LEVEL AIR SPREADING
ACROSS THE FORECAST AREA SOUTH OF INTERSTATE 40. THE MID LEVEL FLOW
IS QUITE WEAK OVER THE UPSTATE...NE GA AND FAR SRN NC AS A SPUR OF
DEEP LAYER RIDGING HAS PUSHED INTO THE FA FROM THE WEST...FINALLY
DISPLACING THE WEAK...MOIST TROUGH THAT HAD BEEN OVER THE REGION FOR
THE PAST SEVERAL DAYS. THE RAP BRINGS A WEAK SHORT WAVE ACROSS
WESTERN NC THIS EVENING. LLVL CONVERGENCE IS INCREASING OVER THE NC
MTNS AND FOOTHILLS AHEAD OF THE WAVE. THE MODELS ARE SPLIT ON
HOW FAR SOUTHEAST THIS CONVECTION GETS. THE GFS KEEPS IT OVER THE
MTNS AND FOOTHILLS...WHILE THE RAP AND NAM PUSH IT INTO THE NRN
SUBURBS OF CHARLOTTE. WITH THE FINGER OF DRIER AIR PUSHING INTO THE
SRN PIEDMONT I/VE GONE WITH A FORECAST THAT KEEPS THE BEST
CONVECTIVE CHANCES OVER THE MTNS AND FOOTHILLS WITH LOWER POPS ALONG
AND SOUTH OF I-85 AND BACK ACROSS THE SW NC MTNS. THIS IS NOT TO SAY
THAT STORMS WON/T PUSH INTO CHARLOTTE LATER THIS EVENING AS THE
ATMOSPHERE IS NOT CAPPED AND IS MODERATELY UNSTABLE. HOWEVER...THIS
DOES NOT LOOK LIKE THE MOST PROBABLE SOLUTION ATTM.
PATCHY DENSE VALLEY FOG IS EXPECTED OVER THE MTNS TONIGHT. ACROSS
THE FOOTHILLS AND PIEDMONT CONSIDERABLY LESS LOW CLOUD COVER IS
ANTICIPATED OWNING TO A MORE WESTERLY COMPONENT TO THE LLVL WIND
FIELD.
A SHORT WAVE CURRENTLY OVER CENTRAL MISSOURI IS EXPECTED TO CROSS
THE FORECAST AREA DURING THE AFTERNOON HOURS ON THURSDAY. THE DEEP
LAYER RH IS CONSIDERABLY HIGHER ON THU THAN TODAY ALONG AND AHEAD OF
THIS WAVE. BY 21 UTC THE FEATURE IS EXPECTED TO BE OVER THE I-77
CORRIDOR AND IT WILL MOVE EAT OF CHARLOTTE BY THE EARLY EVENING. THE
NAM AND GFS BOTH DEVELOP PCPN BY LATE MORNING AHEAD OF THE SHORT
WAVE. THE NAM HAS PCPN ENDING WITH WEAKLY DIVERGENT LLVL FLOW OVER
MOST OF THE FA DEVELOPING BETWEEN 21-00 UTC. THE WAY IT APPEARS
NOW...A BAND OF SHRA AND A FEW TSTMS WILL DEVELOP DEVELOP OVER THE
FOOTHILLS BY LATE MORNING...OR THEY MAY MOVE INTO THE MTNS AS A
REMNANT OF A WEAKENING MCS. THE CONVECTION WILL MOVE ACROSS THE REST
OF THE FOOTHILLS FROM EARLY TO MID AFTN AND EXIT TO THE EAST BY 6 OR
7 PM. THE SHEAR IS WEAK AND CONVECTION ISN/T EXPECTED TO BE HIGHLY
ORGANIZED AND MOST OF THE STORMS SHOULD BE SUB-SEVERE. THIS IS
GENERALLY SUPPORTED BY THE 12 UTC 4KM SPC WRF AS WELL. FOR NOW I/LL
CAP POPS ARE 40 PERCENT...WITH POPS FALLING OFF QUICKLY TOWARD
SUNSET.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 2 PM EDT WEDNESDAY...THE CONSENSUS OF THE MODEL GUIDANCE
MAINTAINS THAT THE PLUME OF DEEPER MOISTURE WILL HAVE SHIFTED
EASTWARD TO THE COASTAL PLAIN. IN THE WAKE OF A WEAK UPPER WAVE...
THE ENVIRONMENT SHOULD BE LESS FAVORABLE FOR DEEP CONVECTION. THE
CHANCE FOR SHOWERS AND STORMS SHOULD DROP IN THE EARLY EVENING AS
THE FORCING AND MOISTURE MOVE OFF TO THE EAST...TO THE POINT WHERE
THE FCST IS DRY EAST OF THE MTNS FROM 03Z ONWARD. THERE COULD BE A
FEW LINGERING SHOWERS OVER THE MTNS UNTIL LATE EVENING.
FRIDAY LOOKS LIKE A RELATIVELY QUIET TRANSITION DAY WHILE WE WAIT
FOR THE FORCING AND MOISTURE TO RELOAD. A STRONG SHORT WAVE OVER THE
UPPER MS VALLEY WILL DIG AN UPPER TROF DOWN OVER THE UPPER MIDWEST
AND GREAT LAKES THROUGH THE DAY...WHICH WILL GRADUALLY TURN THE FLOW
ALOFT MORE SW. UPPER FORCING WILL BE MINIMAL. THERE SHOULD BE ENOUGH
LOW LEVEL MOISTURE AND BUOYANCY TO SUPPORT SCATTERED SHOWERS AND
STORMS DEVELOPING OVER THE HIGHER TERRAIN WITH DIFFERENTIAL
HEATING...WITH SOME OF THE STORMS MOVING OUT OVER THE FOOTHILLS AND
PIEDMONT IN THE AFTERNOON AND EARLY EVENING. THE STORMS EAST OF THE
BLUE RIDGE WILL DIE OFF WITH SUNSET...BUT WILL KEEP THE CHANCE OF
PRECIP GOING OVERNIGHT ON THE W SIDE OF THE MTNS IN CASE SOME
ACTIVITY MOVES IN FROM THE WEST AHEAD OF THE NEXT FRONT.
THE UPPER TROF CONTINUES TO DIG OVER THE MIDWEST/OH VALLEY ON
SATURDAY AS THE WAVE DROPS SOUTHEASTWARD. DEEP MOISTURE MOVES IN
AHEAD OF THE WAVE TO BE ACTED UPON BY IMPROVED UPPER FORCING AS WE
WORK THROUGH THE DAY. THE OPERATIONAL RUNS FROM ALL THREE MODELS ARE
IN FAIRLY GOOD AGREEMENT WITH THE TIMING OF THE MAIN VORT AXIS
REACHING THE GREAT VALLEY LATE IN THE DAY. THE NEW GFS SWEEPS THE
UPPER TROF AXIS ACROSS THE WESTERN CAROLINAS OVERNIGHT WHILE THE 00Z
RUN PUSHES IT THROUGH SUNDAY MORNING. EITHER WAY...BOTH MODELS
SUGGEST AN EARLIER TIMING OF THE MAIN FRONTAL PRECIP BAND. WILL
LIMIT THE PRECIP TO THE CHANCE RANGE FOR THE TIME BEING BUT WILL
PROBABLY NEED A LIKELY POP FOR AT LEAST THE MTNS...BUT IT IS A
MATTER OF WHICH PERIOD TO FOCUS ON...SATURDAY AFTERNOON OR SATURDAY
NIGHT. WILL NOT RULE OUT SOME SEVERE STORMS IF THE FRONT WILL MOVE
THROUGH EARLY ENOUGH. AT THIS POINT...THINK MOST OF THE PRECIP WILL
HAVE MOVED EAST OF THE FCST AREA BY SUNRISE ON SUNDAY...WHICH AGREES
WITH THE HPC POSITION OF THE MAIN FRONT ON THE COAST AT THAT TIME.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 1130 AM EDT WEDNESDAY...AFTER DEALING WITH A SEMI-TROPICAL AIR
MASS FOR THE LAST TWO WEEKS...IT APPEARS AS THOUGH WE ARE IN FOR A
PERIOD OF SPECTACULAR EARLY AUTUMN-LIKE WEATHER EARLY NEXT WEEK. BUT
FIRST...WE HAVE TO GET A FRONT THROUGH THE CAROLINAS EARLY ON
SUNDAY. THE GFS MOVES THE MAIN SHORT WAVE LOBE ACROSS THE WESTERN
CAROLINAS EARLY SUNDAY MORNING WHILE THE ECMWF HAS THIS FEATURE
CROSSING SUNDAY AFTERNOON. THE TIMING IS FASTER THAN PREVIOUSLY
INDICATED...WITH THE MAIN SFC FRONT POTENTIALLY MOVING ACROSS THE
AREA SATURDAY NIGHT. WILL BACK OFF TO A SLIGHT CHANCE ACROSS THE
REGION ON SUNDAY AS A FEW SHOWERS COULD BE TRIGGERED BY A SECONDARY
FRONT. EITHER WAY...THERE IS A STRONG INDICATION THAT THE PRECIP
WILL BE LONG GONE BY SUNSET SUNDAY...SO THE PRECIP CHANCES ARE
ELIMINATED ALTOGETHER AFTER 00Z MONDAY.
THE UPPER TROF AXIS WILL REACH THE EASTERN SEABOARD BY MONDAY
MORNING AND MOVE SLOWLY OFFSHORE THROUGH MIDWEEK...WHILE AN UPPER
ANTICYCLONE REMAINS PARKED OVER THE SRN PLAINS. THE RESULTING UPPER
RIDGE TO OUR NW WILL BRING DRY HIGH PRESSURE BUILDING IN SUNDAY
NIGHT AND MONDAY. ONCE ESTABLISHED...THIS SURFACE HIGH WILL DOMINATE
OUR WEATHER AS IT MOVES SLOWLY PAST TO THE NORTH THROUGH WEDNESDAY.
THIS SHOULD BRING MOSTLY CLEAR SKY...DRY AIR...HIGH TEMPS IN THE
MID/UPPER 70S AND LOW TEMPS IN THE MID/UPPER 50S. THUS...MONDAY AND
TUESDAY WILL FEEL MORE LIKE LATE SEPTEMBER OR EARLY OCTOBER. THE AIR
MASS SHOULD START TO MODIFY A BIT BY WEDNESDAY.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
AT KCLT...A VAST AREA OF DEEP SUBSIDENCE WILL PERSIST ACROSS THE
TERMINAL THIS EVENING AND INTO THE OVERNIGHT. THIS HAS PREVENTED
MUCH IF ANY PCPN OR CLOUDS...LET ALONE CONVECTION AROUND THE AREA.
BELIEVE THIS WILL BE MAINTAINED THROUGH THE OVERNIGHT TO A HIGH
DEGREE. THERE WILL BE SOME APPROACHING MLVL ENERGY AND MOISTURE
OVERNIGHT...BUT THIS WILL HAVE TO MAKE IT OVER THE MTNS AND THROUGH
THE AFOREMENTIONED SUBSIDENCE ZONE. SO...DONT ANTICIPATE A SIGFNT
STORM/PCPN THREAT OVERNIGHT. THERE WILL BE ENOUGH MOISTURE TRAPPED
BENEATH THE INVERSION TO ALLOW STCU TO DEVELOP BEFORE DAYBREAK AND
ALL GUIDANCE POINTS TOWARD A MVFR DECK MOST LIKELY PERSISTING TIL
15Z. THE AFTERNOON CONVECTIVE THREAT REMAINS A REAL POSSIBILITY. THE
GREAT VALLEY S/W WILL BE CROSSING THE PIEDMONT NEAR MAX HEATING SO A
PROB390 TS WITH LIMITING VSBY -SHRA IS EXPECTED AFT 18Z.
ELSEWHERE...ONGOING ISOL/SCT CONVECTION WILL PERSIST ACROSS THE
NW/RN ZONES TONIGHT AND INTO THE EARLY MORNING HRS. ENOUGH SO...THAT
VCTS WAS INCLUDED AT KAVL AND KHKY TIL 03Z. THE MTNS COULD
EXPERIENCE A PROLONGED PERIOD OF SCT PRECIP OVERNIGHT WITH AN
APPROACHING S/W AND AN AMENDMENT MAY BE NEEDED AROUND MIDNIGHT.
WITH THE PRECIP MAINLY ACROSS THE HIGHER TERRAIN TODAY...THE NC MTN
VALLEYS AND FOOTHILLS SHOULD HAVE THE BEST SHOT AT IFR MORNING
FG...PERISTING THROUGH 15Z OR SO. AT THE SC UPSTATE TERMINALS...MVFR
TO POSSIBLY IFR STCU WILL BE THE FLIGHT RESTRICTION CONCERN THROUGH
MID MORNING. SCT CONVECTION WILL BEGIN IN THE MTNS RATHER
EARLY...AROUND 16Z...AND SHIFT EAST OVER THE EASTERN TERMINALS
THROUGH THE AFTERNOON.
OUTLOOK...GRADUAL DRYING FROM THE WEST IS EXPECTED ON THURSDAY
AFTERNOON...WITH DEEPER DRYING ON FRIDAY. A COLD FRONT WILL APPROACH THE
REGION FROM THE NORTHWEST ON SATURDAY AND MOVE EAST OF THE AREA ON
SUNDAY.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PM
NEAR TERM...MCAVOY/SBK
SHORT TERM...PM
LONG TERM...PM
AVIATION...SBK
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
808 PM EDT WED SEP 5 2012
.SYNOPSIS...
DEEP TROPICAL MOISTURE CURRENTLY OVER THE REGION WILL BEGIN TO
PROGRESSIVELY LESSENING THURSDAY INTO FRIDAY. A STRONG COLD FRONT
WILL MOVE OVER THE CAROLINAS THIS WEEKEND FOLLOWED BY HIGH PRESSURE
THAT WILL PROVIDE COOLER AND DRYER WEATHER INTO THE FIRST OF NEXT
WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
530 PM EDT UPDATE...MADE LOWERING CHANGES TO THE POPS/QPF BASED ON
RADAR TRENDS WV IMAGERY AND WRF/ARW OUTPUT. VERY WEAK FORCING ACROSS
THE NRN ZONES AND ACTUAL SUBSIDENCE SOUTH ACROSS THE UPSTATE AND NE
GA HAVE PRECLUDED A SIGFNT CONVECTIVE THREAT IN STRENGTH AND
SPATIALLY THIS EVENING FOR AREAS OUTSIDE THE CENT/NRN NC MTNS AS
WELL AS AREAS SOUTH OF I40. MADE COSMETIC CHANGES TO THE SKY GRIDS
AND MINOR TWEAKS TO TEMPS/TDS...MAINLY ACROSS THE NC MTNS.
THE LATEST WATER VAPOR IMAGERY SHOWS DRIER MID LEVEL AIR SPREADING
ACROSS THE FORECAST AREA SOUTH OF INTERSTATE 40. THE MID LEVEL FLOW
IS QUITE WEAK OVER THE UPSTATE...NE GA AND FAR SRN NC AS A SPUR OF
DEEP LAYER RIDGING HAS PUSHED INTO THE FA FROM THE WEST...FINALLY
DISPLACING THE WEAK...MOIST TROUGH THAT HAD BEEN OVER THE REGION FOR
THE PAST SEVERAL DAYS. THE RAP BRINGS A WEAK SHORT WAVE ACROSS
WESTERN NC THIS EVENING. LLVL CONVERGENCE IS INCREASING OVER THE NC
MTNS AND FOOTHILLS AHEAD OF THE WAVE. THE MODELS ARE SPLIT ON
HOW FAR SOUTHEAST THIS CONVECTION GETS. THE GFS KEEPS IT OVER THE
MTNS AND FOOTHILLS...WHILE THE RAP AND NAM PUSH IT INTO THE NRN
SUBURBS OF CHARLOTTE. WITH THE FINGER OF DRIER AIR PUSHING INTO THE
SRN PIEDMONT I/VE GONE WITH A FORECAST THAT KEEPS THE BEST
CONVECTIVE CHANCES OVER THE MTNS AND FOOTHILLS WITH LOWER POPS ALONG
AND SOUTH OF I-85 AND BACK ACROSS THE SW NC MTNS. THIS IS NOT TO SAY
THAT STORMS WON/T PUSH INTO CHARLOTTE LATER THIS EVENING AS THE
ATMOSPHERE IS NOT CAPPED AND IS MODERATELY UNSTABLE. HOWEVER...THIS
DOES NOT LOOK LIKE THE MOST PROBABLE SOLUTION ATTM.
PATCHY DENSE VALLEY FOG IS EXPECTED OVER THE MTNS TONIGHT. ACROSS
THE FOOTHILLS AND PIEDMONT CONSIDERABLY LESS LOW CLOUD COVER IS
ANTICIPATED OWNING TO A MORE WESTERLY COMPONENT TO THE LLVL WIND
FIELD.
A SHORT WAVE CURRENTLY OVER CENTRAL MISSOURI IS EXPECTED TO CROSS
THE FORECAST AREA DURING THE AFTERNOON HOURS ON THURSDAY. THE DEEP
LAYER RH IS CONSIDERABLY HIGHER ON THU THAN TODAY ALONG AND AHEAD OF
THIS WAVE. BY 21 UTC THE FEATURE IS EXPECTED TO BE OVER THE I-77
CORRIDOR AND IT WILL MOVE EAT OF CHARLOTTE BY THE EARLY EVENING. THE
NAM AND GFS BOTH DEVELOP PCPN BY LATE MORNING AHEAD OF THE SHORT
WAVE. THE NAM HAS PCPN ENDING WITH WEAKLY DIVERGENT LLVL FLOW OVER
MOST OF THE FA DEVELOPING BETWEEN 21-00 UTC. THE WAY IT APPEARS
NOW...A BAND OF SHRA AND A FEW TSTMS WILL DEVELOP DEVELOP OVER THE
FOOTHILLS BY LATE MORNING...OR THEY MAY MOVE INTO THE MTNS AS A
REMNANT OF A WEAKENING MCS. THE CONVECTION WILL MOVE ACROSS THE REST
OF THE FOOTHILLS FROM EARLY TO MID AFTN AND EXIT TO THE EAST BY 6 OR
7 PM. THE SHEAR IS WEAK AND CONVECTION ISN/T EXPECTED TO BE HIGHLY
ORGANIZED AND MOST OF THE STORMS SHOULD BE SUB-SEVERE. THIS IS
GENERALLY SUPPORTED BY THE 12 UTC 4KM SPC WRF AS WELL. FOR NOW I/LL
CAP POPS ARE 40 PERCENT...WITH POPS FALLING OFF QUICKLY TOWARD
SUNSET.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 2 PM EDT WEDNESDAY...THE CONSENSUS OF THE MODEL GUIDANCE
MAINTAINS THAT THE PLUME OF DEEPER MOISTURE WILL HAVE SHIFTED
EASTWARD TO THE COASTAL PLAIN. IN THE WAKE OF A WEAK UPPER WAVE...
THE ENVIRONMENT SHOULD BE LESS FAVORABLE FOR DEEP CONVECTION. THE
CHANCE FOR SHOWERS AND STORMS SHOULD DROP IN THE EARLY EVENING AS
THE FORCING AND MOISTURE MOVE OFF TO THE EAST...TO THE POINT WHERE
THE FCST IS DRY EAST OF THE MTNS FROM 03Z ONWARD. THERE COULD BE A
FEW LINGERING SHOWERS OVER THE MTNS UNTIL LATE EVENING.
FRIDAY LOOKS LIKE A RELATIVELY QUIET TRANSITION DAY WHILE WE WAIT
FOR THE FORCING AND MOISTURE TO RELOAD. A STRONG SHORT WAVE OVER THE
UPPER MS VALLEY WILL DIG AN UPPER TROF DOWN OVER THE UPPER MIDWEST
AND GREAT LAKES THROUGH THE DAY...WHICH WILL GRADUALLY TURN THE FLOW
ALOFT MORE SW. UPPER FORCING WILL BE MINIMAL. THERE SHOULD BE ENOUGH
LOW LEVEL MOISTURE AND BUOYANCY TO SUPPORT SCATTERED SHOWERS AND
STORMS DEVELOPING OVER THE HIGHER TERRAIN WITH DIFFERENTIAL
HEATING...WITH SOME OF THE STORMS MOVING OUT OVER THE FOOTHILLS AND
PIEDMONT IN THE AFTERNOON AND EARLY EVENING. THE STORMS EAST OF THE
BLUE RIDGE WILL DIE OFF WITH SUNSET...BUT WILL KEEP THE CHANCE OF
PRECIP GOING OVERNIGHT ON THE W SIDE OF THE MTNS IN CASE SOME
ACTIVITY MOVES IN FROM THE WEST AHEAD OF THE NEXT FRONT.
THE UPPER TROF CONTINUES TO DIG OVER THE MIDWEST/OH VALLEY ON
SATURDAY AS THE WAVE DROPS SOUTHEASTWARD. DEEP MOISTURE MOVES IN
AHEAD OF THE WAVE TO BE ACTED UPON BY IMPROVED UPPER FORCING AS WE
WORK THROUGH THE DAY. THE OPERATIONAL RUNS FROM ALL THREE MODELS ARE
IN FAIRLY GOOD AGREEMENT WITH THE TIMING OF THE MAIN VORT AXIS
REACHING THE GREAT VALLEY LATE IN THE DAY. THE NEW GFS SWEEPS THE
UPPER TROF AXIS ACROSS THE WESTERN CAROLINAS OVERNIGHT WHILE THE 00Z
RUN PUSHES IT THROUGH SUNDAY MORNING. EITHER WAY...BOTH MODELS
SUGGEST AN EARLIER TIMING OF THE MAIN FRONTAL PRECIP BAND. WILL
LIMIT THE PRECIP TO THE CHANCE RANGE FOR THE TIME BEING BUT WILL
PROBABLY NEED A LIKELY POP FOR AT LEAST THE MTNS...BUT IT IS A
MATTER OF WHICH PERIOD TO FOCUS ON...SATURDAY AFTERNOON OR SATURDAY
NIGHT. WILL NOT RULE OUT SOME SEVERE STORMS IF THE FRONT WILL MOVE
THROUGH EARLY ENOUGH. AT THIS POINT...THINK MOST OF THE PRECIP WILL
HAVE MOVED EAST OF THE FCST AREA BY SUNRISE ON SUNDAY...WHICH AGREES
WITH THE HPC POSITION OF THE MAIN FRONT ON THE COAST AT THAT TIME.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 1130 AM EDT WEDNESDAY...AFTER DEALING WITH A SEMI-TROPICAL AIR
MASS FOR THE LAST TWO WEEKS...IT APPEARS AS THOUGH WE ARE IN FOR A
PERIOD OF SPECTACULAR EARLY AUTUMN-LIKE WEATHER EARLY NEXT WEEK. BUT
FIRST...WE HAVE TO GET A FRONT THROUGH THE CAROLINAS EARLY ON
SUNDAY. THE GFS MOVES THE MAIN SHORT WAVE LOBE ACROSS THE WESTERN
CAROLINAS EARLY SUNDAY MORNING WHILE THE ECMWF HAS THIS FEATURE
CROSSING SUNDAY AFTERNOON. THE TIMING IS FASTER THAN PREVIOUSLY
INDICATED...WITH THE MAIN SFC FRONT POTENTIALLY MOVING ACROSS THE
AREA SATURDAY NIGHT. WILL BACK OFF TO A SLIGHT CHANCE ACROSS THE
REGION ON SUNDAY AS A FEW SHOWERS COULD BE TRIGGERED BY A SECONDARY
FRONT. EITHER WAY...THERE IS A STRONG INDICATION THAT THE PRECIP
WILL BE LONG GONE BY SUNSET SUNDAY...SO THE PRECIP CHANCES ARE
ELIMINATED ALTOGETHER AFTER 00Z MONDAY.
THE UPPER TROF AXIS WILL REACH THE EASTERN SEABOARD BY MONDAY
MORNING AND MOVE SLOWLY OFFSHORE THROUGH MIDWEEK...WHILE AN UPPER
ANTICYCLONE REMAINS PARKED OVER THE SRN PLAINS. THE RESULTING UPPER
RIDGE TO OUR NW WILL BRING DRY HIGH PRESSURE BUILDING IN SUNDAY
NIGHT AND MONDAY. ONCE ESTABLISHED...THIS SURFACE HIGH WILL DOMINATE
OUR WEATHER AS IT MOVES SLOWLY PAST TO THE NORTH THROUGH WEDNESDAY.
THIS SHOULD BRING MOSTLY CLEAR SKY...DRY AIR...HIGH TEMPS IN THE
MID/UPPER 70S AND LOW TEMPS IN THE MID/UPPER 50S. THUS...MONDAY AND
TUESDAY WILL FEEL MORE LIKE LATE SEPTEMBER OR EARLY OCTOBER. THE AIR
MASS SHOULD START TO MODIFY A BIT BY WEDNESDAY.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AT KCLT...A VAST AREA OF DEEP SUBSIDENCE WILL PERSIST ACROSS THE
TERMINAL THIS EVENING AND INTO THE OVERNIGHT. THIS HAS PREVENTED
MUCH IF ANY PCPN OR CLOUDS...LET ALONE CONVECTION AROUND THE AREA.
BELIEVE THIS WILL BE MAINTAINED THROUGH THE OVERNIGHT TO A HIGH
DEGREE. THERE WILL BE SOME APPROACHING MLVL ENERGY AND MOISTURE
OVERNIGHT...BUT THIS WILL HAVE TO MAKE IT OVER THE MTNS AND THROUGH
THE AFOREMENTIONED SUBSIDENCE ZONE. SO...DONT ANTICIPATE A SIGFNT
STORM/PCPN THREAT OVERNIGHT. THERE WILL BE ENOUGH MOISTURE TRAPPED
BENEATH THE INVERSION TO ALLOW STCU TO DEVELOP BEFORE DAYBREAK AND
ALL GUIDANCE POINTS TOWARD A MVFR DECK MOST LIKELY PERSISTING TIL
15Z. THE AFTERNOON CONVECTIVE THREAT REMAINS A REAL POSSIBILITY. THE
GREAT VALLEY S/W WILL BE CROSSING THE PIEDMONT NEAR MAX HEATING SO A
PROB390 TS WITH LIMITING VSBY -SHRA IS EXPECTED AFT 18Z.
ELSEWHERE...ONGOING ISOL/SCT CONVECTION WILL PERSIST ACROSS THE
NW/RN ZONES TONIGHT AND INTO THE EARLY MORNING HRS. ENOUGH SO...THAT
VCTS WAS INCLUDED AT KAVL AND KHKY TIL 03Z. THE MTNS COULD
EXPERIENCE A PROLONGED PERIOD OF SCT PRECIP OVERNIGHT WITH AN
APPROACHING S/W AND AN AMENDMENT MAY BE NEEDED AROUND MIDNIGHT.
WITH THE PRECIP MAINLY ACROSS THE HIGHER TERRAIN TODAY...THE NC MTN
VALLEYS AND FOOTHILLS SHOULD HAVE THE BEST SHOT AT IFR MORNING
FG...PERISTING THROUGH 15Z OR SO. AT THE SC UPSTATE TERMINALS...MVFR
TO POSSIBLY IFR STCU WILL BE THE FLIGHT RESTRICTION CONCERN THROUGH
MID MORNING. SCT CONVECTION WILL BEGIN IN THE MTNS RATHER
EARLY...AROUND 16Z...AND SHIFT EAST OVER THE EASTERN TERMINALS
THROUGH THE AFTERNOON.
OUTLOOK...GRADUAL DRYING FROM THE WEST IS EXPECTED ON THURSDAY
AFTERNOON...WITH DEEPER DRYING ON FRIDAY. A COLD FRONT WILL APPROACH THE
REGION FROM THE NORTHWEST ON SATURDAY AND MOVE EAST OF THE AREA ON
SUNDAY.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PM
NEAR TERM...MCAVOY/SBK
SHORT TERM...PM
LONG TERM...PM
AVIATION...SBK
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
325 PM CDT TUE SEP 4 2012
.DISCUSSION.../ISSUED AT 325 PM CDT/
DIFFUSE BOUNDARY IN NORTHWEST IOWA BEGINNING TO LIFT NORTHWARD AS A
WARM FRONT THIS AFTERNOON AS SURFACE LOW PRESSURE STRENGTHENS OVER
THE BLACK HILLS. MIXING HAS ALLOWED DEWPOINTS TO DRAMATICALLY FALL
THIS AFTERNOON ACROSS THE NORTHWESTERN TWO THIRDS OF THE CWA...WHILE
DEEPER MOISTURE HAS ALLOWED DEWPOINTS TO REMAIN IN THE 60S ACROSS
NORTHWEST IOWA. INSTABILITY CONTINUES TO INCREASE THIS
AFTERNOON...ESPECIALLY ACROSS OUR SOUTHEASTERN HALF OF THE FORECAST
AREA WHERE CAPE VALUES ARE GREATER THAN 1500 J/KG...WITH INCREASING
LAPSE RATES AND STRENGTHENING WESTERLIES BRINGING SHEAR UP AROUND 40
KT.
SO FAR...CAPPING IS PREVENTING CONVECTION FROM DEVELOPING...HOWEVER
WITH KSUX ALREADY 95/65 EXPECT THE CAPPING TO BE SURPASSED SOON.
THE HRRR AND NAM CONTINUE TO DEPICT CONVECTION MOVING NORTHEASTWARD
INTO THE MISSOURI VALLEY...EXTREME SOUTHEAST SOUTH DAKOTA AND
NORTHWEST IOWA LATE THIS AFTERNOON THROUGH THE EVENING. IF
CONVECTION DOES MANAGE TO FIRE IN THIS AREA...STORMS COULD
POTENTIALLY BECOME SEVERE WITH LARGE HAIL TO AROUND WALNUT SIZE AND
WIND GUSTS TO 70 MPH.
FURTHER WEST...HIGH BASED CUMULUS FIELD NOW MOVING INTO OUR WESTERN
BORDER. ISOLATED HIGH BASED CONVECTION WILL BE POSSIBLE IN OUR
WESTERN HALF THIS AFTERNOON AND EVENING...BUT EXPECT LITTLE TO NO
SEVERE WEATHER IN THIS AREA WITH SUCH DRY LOW AND MID LEVELS. AS THE
LOW BEGINS TRACKING EAST NORTHEAST ACROSS THE FORECAST AREA THIS
EVENING AND OVERNIGHT...THE TRAILING COLD FRONT WILL SHIFT THE
CONVECTION INTO CENTRAL AND EASTERN PORTIONS OF THE FORECAST AREA
WHERE CONDITIONS ARE MORE FAVORABLE FOR PRECIPITATION. WINDS WILL
LIKELY BECOME FAIRLY BREEZY FROM THE WEST NORTHWEST LATE TONIGHT.
LOWS TONIGHT WILL RANGE FROM THE MID 50S FAR NORTHWEST TO THE MID
60S FAR SOUTHEAST.
RELATIVELY QUIET WEATHER WITH MILDER TEMPERATURES EXPECTED FOR
WEDNESDAY AS SURFACE HIGH PRESSURE SETTLES IN BEHIND THE EXITING
SYSTEM. NORTH NORTHWEST WINDS WILL REMAIN A LITTLE BREEZY THROUGH
THE DAY...BUT SKIES WILL BE SUNNY AND HIGHS ARE EXPECTED IN THE 70S.
/
HIGH PRESSURE WILL BUILD IN OVER THE AREA FOR WEDNESDAY NIGHT. THUS
TRENDED LOWS TOWARDS THE COOLER SIDE OF GUIDANCE...GENERALLY UPPER
40S TO LOWER 50S. A MID LEVEL WAVE AND SOME CLOUD COVER MAY BEGIN
ENTERING OUR WEST BY LATE NIGHT...THUS DID NOT GO QUITE AS COOL AS I
WOULD HAVE IF COMPLETELY CLEAR SKIES WERE MORE LIKELY. MID LEVEL
FORCING OVERHEAD ON THURSDAY OUT AHEAD OF OUR NEXT WAVE...ALSO
SHOULD SEE DECENT ISENTROPIC LIFT. ATMOSPHERE WILL BE ON THE DRY
SIDE THOUGH...THUS FOLLOWED THE NAM AND GFS IDEA OF A DRY DAY.
HOWEVER SHOULD SEE AT LEAST SOME MID LEVEL CLOUD COVER...AND WITH
DECENT MID LEVEL LAPSE RATES...WOULD NOT BE SURPRISED TO SEE A FEW
ELEVATED SHOWERS AND THUNDERSTORMS. THINK THE ECMWF IS PROBABLY
OVERDOING CONVECTION THURSDAY...BUT LOW POPS MAY NEED TO BE ADDED ON
FUTURE SHIFTS IF MODELS TREND A LITTLE MOISTER IN THE MID LEVELS.
WITH UNCERTAINTY ON CLOUD COVER...FOLLOWED A BLEND OF THE COOLER MOS
AND THE WARMER BIAS CORRECTED NAM FOR HIGHS...GENERALLY MID 70S
SOUTHWEST MINNESOTA TO LOW TO MID 80S ELSEWHERE. SURFACE LOW TO OUR
WEST ON THURSDAY WILL PRODUCE BLUSTERY SOUTH SOUTHEAST WINDS WEST OF
THE JAMES RIVER...WITH GUSTS AROUND 25 TO 30 MPH POSSIBLE.
THE BETTER MOISTURE AND DEEP LAYER FORCING MOVES ACROSS THE CWA
THURSDAY NIGHT. THUS LOOKS LIKE A GOOD CHANCE OF SEEING SOME SHOWERS
IN MOST AREAS. INSTABILITY IS ON THE LOW SIDE...BUT SHOULD SEE AT
LEAST A COUPLE HUNDRED J/KG OF ELEVATED CAPE. SO THINKING WE SEE AT
LEAST SOME EMBEDDED THUNDER. WITH THE CLOUDS AND SHOWERS
AROUND...LOWS WILL STAY A BIT WARMER THAN WEDNESDAY
NIGHT...MAINLY IN THE 50S. COULD SEE SOME LINGERING SHOWERS
ACROSS NORTHWEST IOWA FRIDAY MORNING...BUT THESE SHOULD EXIT THE
AREA BY AFTERNOON AS THE TROUGH AXIS AND DEEPER MOISTURE PUSHES
EAST. EXPECT TO SEE GRADUAL CLEARING FROM NORTH TO SOUTH DURING THE
DAY. MUCH COOLER AIR WILL BE ADVECTED IN BEHIND THE FRONT FOR
FRIDAY...AND THIS COMBINED WITH THE LINGERING CLOUD COVER...SHOULD
HOLD HIGHS IN THE MID 60S TO LOWER 70S.
AS WE HEAD INTO THE WEEKEND...OUR UPPER LEVEL LOW WILL PUSH EAST AND
DIG A DEEP TROUGH INTO THE EASTERN PART OF THE COUNTRY. MEANWHILE A
STRONG RIDGE WILL BUILD INTO THE ROCKIES. OUR AREA WILL REMAIN IN
BETWEEN THE TWO MAKING TEMPERATURES A BIT TRICKY. WE WILL TEND TO
SEE A WARMING TREND INTO EARLY NEXT WEEK...BUT HOW WARM DEPENDS ON
THE STRENGTH AND POSITION OF THE ABOVE MENTIONED FEATURES. TRENDED
HIGHS A BIT ABOVE CONSENSUS SUNDAY THROUGH TUESDAY CLOSER TO THE 0Z
ECMWF AND HPC GUIDANCE. THIS GIVES 70S ON SATURDAY...AND UPPER 70S
TO MID 80S SUNDAY THROUGH TUESDAY. THE NEW 12Z ECMWF HAS TRENDED
STRONGER WITH THE RIDGE AND THUS WARMER WITH TEMPERATURES...SO WILL
HAVE TO MONITOR MODEL TRENDS THIS PERIOD. LOWS FRIDAY AND SATURDAY
NIGHT LOOK TO BE ON THE COOL SIDE...WITH LIGHT WINDS AND CLEAR SKIES
EXPECTED. LOWERED THEM A LITTLE BELOW CONSENSUS...WITH MAINLY MID
AND UPPER 40S EXPECTED. AS THE RIDGE BUILDS CLOSER...LOWS SHOULD
WARM INTO THE 50S BY SUNDAY NIGHT. LOOKS DRY SATURDAY THROUGH
TUESDAY. PROBABLY WILL SEE OUR NEXT COLD FRONT APPROACH SOMETIME
AROUND TUESDAY...HOWEVER AT THIS TIME DOES NOT UPPER TO BE MUCH
MOISTURE WITH IT. /CHENARD
&&
.AVIATION.../FOR THE 18Z TAF ISSUANCE/
VFR CONDITIONS EXPECTED THROUGH 18Z WEDNESDAY. SCATTERED
THUNDERSTORMS WILL DEVELOP AFTER 22Z IN THE 129 CORRIDOR AND
EASTWARD AHEAD OF A COLD FRONT. TEMPORARY MVFR CONDITIONS IN THE
THUNDERSTORMS ARE POSSIBLE AFTER 00Z. GUSTY NORTHWEST WINDS OF 10 TO
20 KNOTS WILL FOLLOW BEHIND THE FRONT OVERNIGHT AND INTO WEDNESDAY
MORNING.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
$$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1100 PM CDT MON SEP 3 2012
.DISCUSSION...
WILL VERY LIKELY BE ABLE TO LET THE REMAINDER OF THE SEVERE
THUNDERSTORM WATCH EXPIRE AT 03Z. TOWARD SUNSET...THE STORMS BECAME
INCREASINGLY LOW CENTROID...AND ELIMINATED THE WESTERN ZONES FROM
THE WATCH. OTHERWISE HAVE ADJUSTED THE GRIDS BASED ON CURRENT
TRENDS...INCREASING LATE EVENING POPS ALONG THE I 90 CORRIDOR...
EAST CENTRAL SD AND EVEN INTO PARTS OF SW MN. CONVERSELY...
BASICALLY ELIMINATED POPS IN OUR SOUTHERN ZONES AS AT LEAST AT THE
MOMENT...THEY ARE GENERALLY CAPPED OFF WITH THE SHORT WAVE DYNAMICS
ALONG AND NORTH OF I 90. THE INDIVIDUAL CELLS CONTINUE TO BUILD
SLIGHTLY TO THE SOUTH...SO IT IS POSSIBLE THAT SIOUX FALLS ITSELF
MAY BE GET HIT AROUND 04Z...AND THUS INCREASED POPS TO A STRONG
SCATTERED. IT IS A BIT SURPRISING THAT THE STORMS HAVE HELD THIS
INTENSITY FOR THIS LONG...KNOWING THAT THEY WERE LIKELY TIED TO THE
SURFACE BOUNDARY EARLIER THIS EVENING. BUT THE SHORT WAVE MAY BE
STRONGER THAN THE EARLIER MODELS WERE INDICATING. FOR OTHER
ELEMENTS...LOW TEMPERATURES STILL LOOK GOOD. GRID UPDATE IS OUT AND
WILL UPDATE THE ZFP VERY SHORTLY. /MJF
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
ISOLATED HIGH BASED THUNDERSTORMS FROM KFSD-KMML AS OF 04Z WILL MOVE
EAST THROUGH MN/IA NORTH OF HIGHWAY 18 THROUGH 08Z. ERRATIC GUSTY
WINDS POSSIBLE WITH THE STORMS...WHICH SHOULD BE EAST OF TAF SITES
BY START OF 06Z TAF PERIOD. WITH LOW LEVEL MOISTURE AND LIGHT WINDS
WITHIN WEAK SURFACE RIDGE AXIS OVER NORTHWEST IOWA...COULD SEE SOME
POCKETS OF MVFR FOG DEVELOP TOWARD DAYBREAK AND WILL KEEP SOME LIGHT
FOG FOR KSUX 10-14Z. CONVECTIVE CHANCES INCREASE INTO THE MISSOURI
RIVER VALLEY LATE TUESDAY AFTERNOON...AND EXPAND DURING THE EVENING
AS UPPER WAVE/ASSOCIATED COLD FRONT APPROACHES. WILL ADD MENTION OF
THUNDER INTO KFSD/KSUX TUESDAY EVENING...HOWEVER CONFIDENCE IN
TIMING/LOCATION SOMEWHAT UNCERTAIN AND SUBJECT TO CHANGE IN FUTURE
TAF ISSUANCES.
&&
.PREV DISCUSSION.../ISSUED AT 315 PM CDT/
LIGHT SHOWERS MAINLY CONFINED TO NORTHWEST IOWA SO FAR THIS
AFTERNOON. MID LEVEL CLOUDS ALSO DISSIPATING IN OUR WEST ALLOWING
FOR DECENT HEATING. DEWPOINTS HAVE FALLEN RAPIDLY ONCE MIXING
COMMENCED...WITH DRY AIR ALOFT. THIS WAS SHOWN WELL BY THE HRRR AND
NAM. BOTH OF THESE MODELS SHOW SOME DEWPOINT RECOVERY BY LATER THIS
AFTERNOON RIGHT AHEAD OF THE APPROACHING FRONTAL BOUNDARY. THE
QUESTION IS WHETHER THEY RECOVER ENOUGH TO HELP BREAK THE CAP. HRRR
HAS BACKED OFF SOME OF ITS EARLIER IDEA OF SCATTERED TO NUMEROUS
STORMS FORMING AS THE BOUNDARY ENTERED OUR CWA. STILL THINKING WE
POSSIBLY GET SOME ISOLATED DEVELOPMENT AFTER 4 OR 5 PM WEST OF THE
JAMES RIVER. FULL SUN COMBINED WITH CONVERGENCE ALONG THE FRONT AND
AN APPROACHING SHORTWAVE...MAY BE ENOUGH TO AT LEAST GET ISOLATED
DEVELOPMENT. CAPE COULD BE AROUND 1500 J/KG NEAR THE BOUNDARY...AND
A VEERING WIND PROFILE WITH DECENT WINDS ALOFT SHOULD RESULT IN
AROUND 40 KTS EFFECTIVE SHEAR. SO ANY STORM THAT IS ABLE TO FORM
COULD BE SEVERE...WITH STRONG WINDS AND LARGE HAIL. STORMS WOULD
MOVE EAST OR EAST SOUTHEAST...BUT THINKING MOST ACTIVITY WILL BE
DIURNALLY DRIVEN AND THUS DIE AS THE EVENING PROGRESSES. KEPT CHANCE
POPS MAINLY ALONG AND WEST OF THE JAMES RIVER....WITH SLIGHT CHANCE
THROUGH THE REST OF THE CWA...JUST IN CASE STORMS PERSIST ALONG
THERE OUTFLOW LONGER THAN EXPECTED. SKIES SHOULD CLEAR LATER
TONIGHT...WITH LOWS IN THE 50S AND 60S. COULD SEE SOME FOG
DEVELOPMENT IN THE SOUTH...ESPECIALLY WHERE RAIN HAS FALLEN TODAY IN
NORTHWEST IOWA.
TUESDAY SHOULD START MOSTLY SUNNY WITH HIGHS IN THE 80S AND 90S.
TRICKY PART OF TUESDAYS FORECAST WILL BE HOW FAR SOUTH THE BOUNDARY
MAKES IT LATE TONIGHT...AND HOW QUICKLY IT PUSHES BACK NORTH AS A
WARM FRONT TOMORROW BEFORE THE COLD FRONT PUSHES THROUGH. WITH
STABLE DRIER AIR NORTH OF THIS BOUNDARY...CONVECTION CHANCES WILL BE
CONFINED TO ALONG AND SOUTH OF IT DURING THE DAY...AS ANOTHER
SHORTWAVE PUSHES ACROSS. NAM IS THE FURTHEST SOUTH WITH THE
BOUNDARY...ONLY PUSHING AS FAR NORTH AS SPENCER TO YANKTON BY
AFTERNOON. THE GFS IS FURTHEST NORTH...WITH THE ECMWF IN BETWEEN.
NAM HAS BEEN A LITTLE TOO AGGRESSIVE WITH FRONTS...BUT GENERALLY HAS
BEEN THE BEST. THUS TEND TO THINK A SOLUTION SOMEWHERE BETWEEN THE
ECMWF AND NAM WILL BE CLOSEST. THIS WOULD GENERALLY KEEP THE
THUNDERSTORM THREAT SOUTH OF INTERSTATE 90 THROUGH 7 PM TUESDAY.
STORMS THAT DO FORM IN THE AFTERNOON WILL HAVE THE POTENTIAL OF
BEING SEVERE...WITH AROUND 2000 J/KG OF CAPE AND DEEP LAYER SHEAR OF
40 KTS. LARGE HAIL AND STRONG WINDS WILL BE POSSIBLE IN ANY STORM
THAT DOES FORM. CAP SHOULD HOLD STRONG FOR MUCH OF THE
AFTERNOON...HOWEVER CONTINUED HEATING AND THE APPROACHING WAVE
SHOULD BREAK IT AT SOME POINT EITHER LATE AFTERNOON OR EVENING.
/CHENARD
THAT APPROACHING WAVE AND FRONT SHOULD BRING MORE NUMEROUS SHOWERS
AND THUNDERSTORMS TUESDAY EVENING...MAINLY TO THE EASTERN PART OF
THE AREA WHERE MOISTURE POOLING AND INFLOW WILL BE GOOD. SYSTEM
MOVING FAST ENOUGH AND MID TO UPPER FLOW IS STRONG ENOUGH SO THAT
RAINFALL AMOUNTS SHOULD NOT BE TOO HIGH. FRONT WILL BE MOVING ACROSS
AREA WITH COOLER AIR SPREADING IN BEHIND IT...AND PRECIPITATION
DECREASING STEADILY AFTER MIDNIGHT. GUIDANCE SEEMS OK AT THIS POINT
ON COOLING FOR LOW TEMPERATURES. MOVEMENT LOOKS FAST ENOUGH TO KEEP
OUT ANY MENTION OF LINGERING SHOWERS FOR WEDNESDAY AND DRYING
CERTAINLY LOOKS STRONG...SO WE SHOULD BE HEADING TO A SUNNY/MOSTLY
SUNNY DAY WEDNESDAY AFTER MORNING CLOUDS SOUTHEAST DECREASE. LATE
THURSDAY INTO FRIDAY LOOKS LIKE ANOTHER THREAT OF SHOWERS AND STORMS
AS NEXT WAVE AND COLD FRONT IS PRECEDED BY FAVORABLY THERMAL
ADVECTION PATTERN. WILL GO WITH LOW POPS AS PER GUIDANCE FOR NOW BUT
OVERALL THREAT SEEMS A LITTLE HIGHER AND WHEN WE CAN NARROW DOWN THE
TIMING BETTER...THE POPS FOR AT LEAST PART OF THAT TIME...PERHAPS
THURSDAY NIGHT...MAY GO UP. THIS SYSTEM WILL BRING IN EVEN COOLER
AIR FOR FRIDAY AND SATURDAY. SOLIDLY DRY PATTERN WILL ALSO DEVELOP
BEHIND THIS SYSTEM...AND THE DRY PATTERN WILL REMAIN IN PLACE AS
SLOW BUT STEADY WARMING SETS IN SUNDAY AFTERNOON THROUGH MONDAY.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
610 PM CDT WED SEP 5 2012
.SHORT TERM...TONIGHT THROUGH SATURDAY
329 PM CDT WED SEP 5 2012
FOCUS THIS FORECAST PERIOD WAS ON THE NEXT WEATHER SYSTEM COMING
INTO THE AREA THURSDAY NIGHT AND FRIDAY. CHANCES ARE INCREASING
FOR A SHOWER PRODUCER.
CURRENT FRONTAL POSITION TOUGH TO DISCERN RIGHT NOW...BUT MAYBE
THE MORE IMPORTANT ELEMENT IS WHERE THE CONVERGENCE AND
INSTABILITY IS. SURFACE MOISTURE CONVERGENCE CURRENTLY LIES ACROSS
THE SOUTHERNMOST FORECAST AREA PER SPC 19Z ANALYSIS. MLCAPE IS UP
TO 1500 J/KG THERE WITH CIN ABOUT 50 J/KG. THERE IS SOME WEAKER
CONVERGENCE ACROSS NERN IA ALONG ANOTHER WEAK WIND SHIFT FROM WEST
TO N-NW.
THE NEXT FEW HOURS HOLD A CHANCE FOR ISOLATED TSRA ACROSS NERN IA
AND SWRN WI BUT THIS CHANCE SHOULD SHIFT SOUTHEAST BY EVENING.
CURRENTLY DO NOT HAVE A TSRA CHANCE IN THE FORECAST THIS AFTERNOON
OR EVENING.
12Z 250 MB RAOB INFORMATION SHOWING A NICE HEIGHT FALL/RISE/FALL
SIGNAL OVERHEAD AND UPSTREAM INTO WRN ALBERTA...WITH THE
WESTERNMOST FALL OF OVER 100M/12HR ASSOCIATED WITH THE FRIDAY
SHORTWAVE TROUGH SHIFTING SOUTHEAST. A NICE WARM POOL OF AIR SEEN
WITH THAT SHORTWAVE TROUGH OVER ALBERTA/BRITISH COLUMBIA THERE
TOO..AND 100KT JET CORE...WITH LATEST RUC ANALYSIS SHOWING THE
TROPOPAUSE FOLD DOWN TO 500MB OVER CENTRAL BC. SHORTWAVE RIDGE TO
BUILD IN FOR TONIGHT/THURSDAY IS CENTERED NEAR KGGW WITH 80M/12HR
HEIGHT RISES AT 250 MB.
RIDGE BUILDING WILL CONTINUE OVERNIGHT WITH ENOUGH 0-2KM AGL FLOW
/GREATER THAN 10KTS/ TO KEEP MISSISSIPPI RIVER VALLEY FOG OUT OF
THE PICTURE. HOWEVER...HAVE KEPT THE WI RIVER VALLEY FOG IN FOR
THU MORNING AS MORE ORTHOGONAL NW FLOW WILL ALLOW FOR DECOUPLING
IN THE BOUNDARY LAYER. PLUS...DEWPOINTS WILL BE HIGHEST IN THAT
AREA OVERNIGHT...HAVE SLOWED THE DRIER AIR ADVECTION.
ALBERTA/BC SHORTWAVE TROUGH TO BRING FALL-LIKE DYNAMICS TO THE AREA
THURSDAY NIGHT AND INTO FRIDAY. PRETTY GOOD CONSISTENCY IN THE
LARGER SCALE FORCING PRESENTED IN THE 05.12Z NAM/GFS THIS MORNING
AND BECAUSE OF THIS...HAVE RAISED RAIN CHANCES LATE THURSDAY NIGHT
INTO FRIDAY. THE SHORTWAVE ROUGH ENERGY SPLITS AS IT HEADS
SOUTHEAST WITH A PORTION MOVING IN FROM THE DAKOTAS AND THE SECOND
COMING IN FROM THE SOUTHWEST. THESE EACH HAVE A SMALL JET CORE
ASSOCIATED WITH THEM AND BY LATER THU NIGHT-FRIDAY...IT APPEARS THEY
INTERACT IN A COUPLED JET SCENARIO OVER THE AREA FOR GOOD DIVERGENCE
ALOFT. A STRONG BAROCLINIC ZONE IN THE 700-850MB LAYER WITH THE
INITIAL SHORTWAVE TROUGH WILL ALSO CREATE A W-E RAIN BAND WITH ITS
FORCING IN FRONTOGENESIS FROM CENTRAL MN-NRN WI...WHICH SLOWLY
SHIFTS INTO THE NWRN FORECAST AREA BY FRIDAY MORNING. THIS IS
SOMEWHAT IN CONCERT WITH 500-300MB QVECTOR CONVERGENCE.
MEANWHILE...BACK AT THE RANCH...THETA-E CONVERGENCE IN THE LOW-
LEVELS WILL ALSO START INCREASING IN THE WRN AND NRN FORECAST BY
12Z FRIDAY. THEN...QG FORCING INCREASES AS SECOND SHORTWAVE TROUGH
ENERGY PIECE SHIFTS ACROSS THE SOUTHERN FORECAST AREA. 05.12Z
ECMWF HAS THESE COMPONENTS...JUST FURTHER NORTH AND
SOUTH...SPLITTING AROUND THE FORECAST AREA.
05.09Z SREF DATA SUGGESTS ANY CAPE OVER 500 J/KG SHOULD REMAIN SOUTH
OF THE FORECAST AREA WITH DEWPOINTS STRUGGLING TO REACH MIDDLE 50S.
HOWEVER...WITH STEEPER LAPSE RATES IN THE MID-LEVELS AND STRONGER
FRONTOGENESIS...COULD SEE SOME THUNDER THU NIGHT UNTIL IT IS USED
UP.
OVERALL...THE SIGNALS ARE BEST IN THE NRN AND SRN FORECAST
AREA...BUT LARGE ENOUGH SIGNALS EXIST TO MOVE TOWARD A LIGHT RAIN
SHOWER SOLUTION FOR LATE THURSDAY NIGHT AND INTO FRIDAY. AMOUNTS MAY
NOT BE LARGE WITH LIMITED INSTABILITY IN THE FORECAST AREA...AROUND A
QUARTER OF AN INCH TOTAL. RAIN SHOULD CLEAR QUICKLY EAST LATER ON
FRIDAY. CURRENTLY THE FORECAST TEMPERATURES HAVE A 10F DIURNAL RANGE
FRIDAY...AND IF IT SHOWERS ALL DAY...IT WOULD LIKELY BE ABOUT 5F.
CONFIDENCE IS INCREASING ON THE RAIN EVENT...BUT NOT HIGH ENOUGH TO
CUT HIGHS FRIDAY MORE. THIS WILL BE NEEDED IF WE INCREASE THE RAIN
CHANCES MORE IN COMING FORECASTS.
NOTE...THE NCEP GFS MODEL WAS CHANGED TODAY AT 12Z TO TRY AND
SOLVE THE COLD/MOIST BIAS IN THE LOWEST 3KM AGL THAT HAS BEEN
EVIDENT SINCE LAST YEAR. IT APPEARED BETTER WITH ITS
INITIALIZATION IN THE LOW LEVELS.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
329 PM CDT WED SEP 5 2012
WITH NORTHWEST FLOW OVER THE AREA FOR THE WEEKEND...THERE IS SOME
SIGNAL FOR A SHORTWAVE TROUGH TO SHIFT THROUGH THE GREAT LAKES
SATURDAY NIGHT. AT THIS TIME THE 05.00Z ECMWF AND 05.12
GEM/GFS/ECMWF REMAIN CONSISTENT IN SHOWERS OVERNIGHT IN EASTERN
WISCONSIN. THERE IS A VERY DEEP TROPOSPHERIC QG FORCING SIGNAL
MOVING THROUGH EASTERN WI PER THE 05.12Z ECMWF. THUS...HAVE ADDED
SOME SMALL SHOWER CHANCES TO CENTRAL WI AREAS. IF THIS SIGNAL
CONTINUES...MORE CLOUD AND HIGHER RAIN CHANCES WILL BE NEEDED. IT
LOOKS LIKE A FAST MOVER TO LIMIT THE IMPACT ON THE WEEKEND
WEATHER.
RIDGE BUILDING THEN IN CONTROL OF WEATHER SUN-TUE WITH
TEMPERATURES WARMING. THERE ARE SOME SIGNALS THAT TUESDAY COULD BE
IN A PREFRONTAL SOUTHWESTERLY FLOW WITH 90F POSSIBLE. HAVE BUMPED
HIGHS ABOUT 3F AND THE ONLY THING HOLDING OFF THE FORECAST OF
WARMER HIGHS IS THE TIMING OF A STRONG FRONT AT DAY 6 CAN GET
TRICKY.
&&
.AVIATION...
610 PM CDT WED SEP 5 2012
VALLEY FOG AT KLSE A CONCERN TONIGHT WITH EARLIER RAINS ADDING A
NEAR SURFACE MOISTURE SOURCE...WHILE AN AREA OF HIGH PRESSURE BUILDS
IN FROM THE WEST LEADING TO SKC/SCT SKIES AND LIGHT SFC WINDS.
HOWEVER...BUFKIT RAP/NAM12 SOUNDINGS KEEP THE LIGHTER WINDS CONFINED
TO THE NEAR SFC...UNDER 300 FT. ALSO...THE MODELS TREND TOWARD
ADVECTING IN DRIER AIR OVERNIGHT. SO ANY DIURNAL EARLY EVENING
REBOUND IN THE TDS WOULD BE OFFSET. THINK THE CON FOG FACTORS ARE
FAVORED OVER THE PROS FOR NOW...AND WILL KEEP KLSE FG/BR FREE. WILL
CONTINUE TO MONITOR. VFR CONDITIONS SHOULD PREVAIL FOR THE BETTER
PART OF THU.
THE HIGH WILL EXIT EAST THU NIGHT...ALLOWING FOR A COUPLE UPPER
LEVEL SHORTWAVE TROUGHS TO TAKE AIM ON THE UPPER MISSISSIPPI RIVER
VALLEY. FORCING/LIFT AND INCREASING SATURATION WILL RESULT IN CLOUDS
AND A CHANCE FOR SHRA. THE BETTER RAIN CHANCES SHOULD LIE
NORTH-SOUTH OF KRST/KLSE...WHERE THE SHORTWAVES ARE EXPECTED TO
TRAVERSE. BUT ENOUGH LIFT/MOISTURE FOR SOME SCT SHRA LATE THU NIGHT.
LITTLE IF ANY INSTABILITY...SO DON/T EXPECT A TS THREAT AT THIS
TIME.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
329 PM CDT WED SEP 5 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM....BAUMGARDT
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
256 PM CDT TUE SEP 4 2012
.SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT
256 PM CDT TUE SEP 4 2012
MAIN FORECAST CONCERNS ARE ON CONVECTION THROUGH WEDNESDAY MORNING
AND ASSOCIATED SEVERE WEATHER POTENTIAL.
CURRENTLY AS OF 20Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A POTENT SHORTWAVE TROUGH OVER SOUTHERN SASKATCHEWAN INTO
EASTERN MONTANA...THEN NEAR ZONAL TO SLIGHT SOUTHWEST FLOW STREAMING
EAST INTO NEW ENGLAND. WITHIN THIS FLOW...A SHORTWAVE WAS PRESENT
OVER FAR WESTERN WISCONSIN...WITH SOME WEAK RIDGING RIGHT BEHIND IT
OVER MINNESOTA. MOSTLY SUNNY SKIES AFTER THE FOG BURNED OFF THIS
MORNING HAS ALLOWED FOR STRONG HEATING ACROSS THE AREA. WITH 12Z
RAOBS HAVING 850MB TEMPS AROUND 18C...TEMPERATURES HAVE CLIMBED INTO
THE MID TO UPPER 80S. DEWPOINTS REMAIN MUGGY FOR THIS TIME OF
YEAR...IN THE MID 60S TO AROUND 70. THE COMBINATION OF THE
TEMPERATURES AND DEWPOINTS HAS RESULTED IN MLCAPE VALUES OF
2000-3000 J/KG WITH LITTLE CIN. AT THE SURFACE...LOW PRESSURE WAS
NEAR AITKIN MN WITH A DRY-LINE ARCING THROUGH NORTHWEST WI INTO
SOUTHEAST MN. PLENTY OF CUMULUS GOING UP AHEAD OF THIS DRY LINE.
STORMS ARE EXPECTED TO DEVELOP IN THE NEXT HOUR OR TWO OUT OF THIS
CUMULUS FIELD. BIG CONCERN FOR SEVERE WEATHER IS WIND GIVEN
MID-LEVEL DRY AIR PRESENT...SEEN ON BOTH WATER VAPOR AND THE 12Z MPX
SOUNDING. TO THE WEST...FAIRLY QUIET ACROSS THE DAKOTAS AHEAD OF
THE POTENT TROUGH. HOWEVER...ANOTHER SURFACE LOW HAS DEVELOPED AHEAD
OF IT NEAR PIERRE. IN ADDITION... GOES PRECIPITABLE WATER IMAGERY
SHOWS MOISTURE BEGINNING TO SURGE TO THE NORTHWEST THROUGH EASTERN
NEBRASKA AHEAD OF THE SURFACE LOW/UPPER TROUGH.
REST OF THE AFTERNOON...ASSUMING CONVECTION FIRES IN THE CUMULUS
FIELD...WHICH IS INDICATED BY MANY MESO-MODELS...EXPECTING IT TO
PROPAGATE EAST-SOUTHEAST QUICKLY DURING THE NEXT FEW HOURS. THIS IS
DUE TO THE DRY MID LEVEL AIR ALLOWING FOR RAPID MOVING OUTFLOW AS
WELL AS THE MAIN SHORTWAVE ACCOMPANYING IT SHIFTING INTO EASTERN
WISCONSIN BY 00Z. THEREFORE...THINKING THE SEVERE THREAT AND
PROBABLY MUCH OF THE PRECIPITATION WILL END BY 00Z. ONLY CAVEAT
COULD BE IN FAR SOUTHWEST WI AND FAR NORTHEAST IA WHERE THERE ARE
HINTS THE TAIL END OF CONVECTION COULD STALL OUT. KEPT SOME HIGHER
CHANCES OF PRECIPITATION DOWN THERE JUST IN CASE.
TONIGHT AND WEDNESDAY...THE POTENT SHORTWAVE OVER EASTERN MONTANA IS
FORECAST TO MOVE INTO WESTERN MINNESOTA BY 12Z WEDNESDAY. AS THIS
OCCURS...THE MOISTURE SEEN LIFTING UP THROUGH EASTERN NEBRASKA RIGHT
NOW IS GOING TO GET ISENTROPICALLY LIFTED UP TOWARDS US. SO AFTER
SOME BRIEF SHORTWAVE RIDGING AND SUBSIDENCE THIS EVENING...ANOTHER
ROUND OF SHOWERS AND THUNDERSTORMS LOOKS LIKELY. DEVELOPMENT MAY
OCCUR SOUTH OF I-90 AS EARLY AS 03Z AS SUGGESTED BY THE 04.12Z
NAM/GFS. BETTER POTENTIAL FOR PRECIPITATION FOR THE ENTIRE AREA IS
AFTER MIDNIGHT AS THE SHORTWAVE APPROACHES AND 850MB MOISTURE
TRANSPORT REALLY INCREASES. MID-LEVEL FLOW IS NICELY DIFFLUENT TOO
AHEAD OF THE WAVE...AIDING IN FORCING. MCS DEVELOPMENT IS CERTAINLY
POSSIBLE...AS NOTED BY THE 04.12Z ECMWF/UKMET/CANADIAN/NAM.
REGARDING SEVERE CONCERN...1-6KM SHEAR VALUES VARY FROM MODEL TO
MODEL. NAM IS ON THE ORDER OF 30-40 KT WHILE THE GFS IS 20-30KT. THE
NAM WOULD DEFINITELY GIVE A SEVERE WEATHER CONCERN...WITH BOTH HAIL
AND DAMAGING WINDS POSSIBLE. THE GFS NOT AS MUCH SO. THEREFORE...
THINK THE SPCS DAY 1 OUTLOOK SLIGHT RISK IDEA IS APPROPRIATE. A BIG
NOTE...THERE IS A POSSIBILITY MCS DEVELOPMENT COULD OCCUR FARTHER
SOUTH SAY MORE OVER IOWA. IF IT DOES...CORFIDI VECTORS WOULD TAKE IT
SOUTHEAST...LIMITING SOME OF THE CONVECTIVE ACTIVITY OVER THE
FORECAST AREA. SHORTWAVE TROUGH IS PROGGED TO HEAD EAST TO CENTRAL
UPPER MICHIGAN AND LAKE MICHIGAN BY 18Z...ALLOWING STRONG ISENTROPIC
DESCENT TO FILTER INTO THE AREA AND CLEAR OUT THE
PRECIPITATION/CLOUDS. COLD FRONTAL BOUNDARY TOO LOOKS TO BE THROUGH
THE AREA AROUND 18Z. 850MB TEMPS FALL QUITE A BIT WITH THE PASSAGE
OF THE TROUGH. THROUGH 12Z WEDNESDAY...THEY HOVER BETWEEN 18-20C. BY
00Z THURSDAY...THOUGH... THEY FALL TO 12-14C. THUS...ANTICIPATE A
COOLER DAY TOMORROW...MORE AROUND SEASONABLE NORMALS.
WEDNESDAY NIGHT AND THURSDAY...TROUGHING OVER THE FORECAST AREA AS A
RESULT OF THAT POTENT SHORTWAVE MOVING THROUGH WEDNESDAY LOOKS TO BE
SHORT-LIVED. THAT IS BECAUSE ANOTHER POTENT TROUGH IS PROGGED TO
DROP SOUTH INTO MONTANA BY 12Z THURSDAY. THERE WILL BE ENOUGH
SUBSIDENCE AND DRY AIR PERSISTING IN THE WAKE OF WEDNESDAYS
SHORTWAVE SUCH THAT WEDNESDAY NIGHT STAYS DRY. AT THE SURFACE...A
HIGH PRESSURE RIDGE IS PROGGED TO BUILD INTO WESTERN PORTIONS OF THE
FORECAST AREA BY 12Z THURSDAY. GIVEN THE RIDGE POSITION...ENOUGH OF
A NORTHWESTERLY BREEZE SHOULD OCCUR TO PREVENT ANY FOG AT LEAST IN
THE MISSISSIPPI RIVER VALLEY. OTHER SMALLER VALLEYS LIKE THE
WISCONSIN MAY STILL BE SUSCEPTIBLE...THOUGH. COOLER NIGHT LIKELY
WITH WINDS LIGHTENING UP THROUGH THE NIGHT AS WELL AS CLEAR SKIES.
SOME OF THE TYPICAL COLD SPOTS COULD FALL INTO THE MID 40S. ON
THURSDAY...THAT POTENT TROUGH DIGS DOWN A LITTLE MORE THROUGH
MONTANA...SETTING UP WEST-SOUTHWEST MID LEVEL FLOW OVER THE AREA.
WITHIN THIS FLOW...THERE COULD BE A SHORTWAVE SKIMMING ACROSS
NORTHERN WISCONSIN IN THE AFTERNOON...BUT OTHERWISE MODELS DO NOT
SHOW ANY OTHER SHORTWAVES OF SIGNIFICANCE. HOWEVER..WITH THAT POTENT
TROUGH DIGGING A LITTLE MORE...IT SETS UP A 310-315K ISENTROPIC
LIFT/MID-LEVEL FRONTOGENESIS ZONE DOWNSTREAM ACROSS THE NORTHERN
PLAINS INTO OUR REGION. LOOKS LIKE ANY PRECIPITATION RESULTING FROM
THIS FORCING WILL STAY WEST OF OUR AREA...BUT AN INCREASE IN
MID/HIGH CLOUDS IS LIKELY...ESPECIALLY IN THE AFTERNOON. 850MB TEMPS
OF 12-14C COMBINED WITH A DECENT AMOUNT OF SUN AND THE DRY AIR
SHOULD ALLOW FOR TEMPERATURES TO CLIMB INTO THE MID TO UPPER 70S.
THURSDAY NIGHT AND FRIDAY...THE POTENT TROUGH OVER MONTANA IS
FORECAST TO DIG SOUTHEAST DURING THIS PERIOD...BEING PUSHED BY
RIDGING DROPPING DOWN INTO SOUTH CENTRAL CANADA. BY 00Z SATURDAY...A
LONG WAVE TROUGH SHOULD EXTEND FROM NORTHEAST ONTARIO...INTO THE
FORECAST AREA AND INTO NEBRASKA. THE MAIN ISSUE WITH THIS POTENT
TROUGH COMING TOWARDS THE AREA IS WHERE DOES THE FRONTOGENESIS ZONE
AHEAD OF IT LAY UP...AND THUS THE ASSOCIATED PRECIPITATION. THE
04.00Z ECMWF KEPT THE BULK OF IT ACROSS IOWA THURSDAY NIGHT AND INTO
ILLINOIS AND MISSOURI ON FRIDAY...THUS FOR THE MOST PART OUR
FORECAST AREA ENDS UP DRY. THE 04.12Z NAM IS FARTHER NORTH...HAVING
PRECIPITATION FALL SOUTH OF INTERSTATE 94 AFTER MIDNIGHT THURSDAY
NIGHT AND FRIDAY. 04.12Z GFS IS A LITTLE MORE INTERESTING. THE MODEL
SUGGESTS SOME HIGHER LEVEL FRONTOGENESIS PRODUCING A BAND OF MOSTLY
LIGHT RAIN...WHICH SLOWLY DROPS SOUTH THROUGH THE AREA AFTER
MIDNIGHT THURSDAY NIGHT THROUGH FRIDAY. THESE BANDS SOMETIMES VERIFY
AND OTHER TIMES NOT. OVERALL...THE BULK OF THE PRECIPITATION IN THE
GFS FALLS TO THE SOUTH. IN ANY EVENT...ALL MODELS SUGGEST A NEED TO
INCREASE PRECIPITATION CHANCES UP TO 40 FOR NOW...MAINLY SOUTH OF
I-90. FURTHER REFINEMENTS WILL BE NEEDED AS WE GET CLOSER TO THIS
PERIOD. WITH MORE CLOUDS AS WELL AS COOLER AIR COMING IN WITH THE
UPPER TROUGH...ANTICIPATE THIS PERIOD TO BE MUCH COOLER THAN AS OF
LATE. THIS WILL BE ESPECIALLY TRUE ON FRIDAY AS 850MB TEMPS FALL TO
6-9C. HIGHS ON FRIDAY MAY GET STUCK IN THE 60S...ESPECIALLY IF IT
RAINS ALL DAY LIKE THE NAM.
.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY
256 PM CDT TUE SEP 4 2012
04.12Z ECMWF/GFS/CANADIAN AND GFS ENSEMBLES ARE A LITTLE DIFFERENT
AMONGST EACH OTHER TODAY COMPARED TO YESTERDAY...MOSTLY WITH REGARDS
TO HANDLING WHETHER THE UPPER TROUGH COMING THROUGH THE FORECAST
AREA FRIDAY ENDS UP CLOSING OFF IN THE OHIO RIVER VALLEY.
INTERESTINGLY...THE 04.12Z ECMWF/CANADIAN AND GFS HAVE NOW
FLIP-FLOPPED WITH EACH OTHER...WITH THE ECMWF/CANADIAN NOW MORE
PROGRESSIVE AND THE GFS CLOSING OFF. FOR OUR AREA...THOUGH...WHICH
EVER SOLUTION PANS OUT REALLY DOESNT MATTER...AS BOTH SCENARIOS
BUILD HIGH PRESSURE INTO THE FORECAST AREA FOR THE WEEKEND. SO MAYBE
AFTER A FEW LINGERING SHOWERS IN NORTHEAST IA/SOUTHWEST WI FRIDAY
NIGHT...EXPECT DECREASING CLOUDS AND DRY WEATHER FOR THE WEEKEND.
CERTAINLY LOOKS COOL COMPARED TO WHAT HAS BEEN SEEN RECENTLY...
THANKS TO 850MB TEMPS OF 6-8C ON SATURDAY AND 10-12C ON SUNDAY.
WOULD NOT BE SURPRISED IF SOME OF THE TYPICAL COLD SPOTS END UP
SEEING SOME UPPER 30S.
FOR EARLY NEXT WEEK...UPPER RIDGING OVER THE WESTERN U.S. IS
FORECAST TO BUILD UP INTO THE FORECAST AREA...BUT FLATTEN PRETTY
QUICKLY BY TUESDAY AS A SHORTWAVE TROUGH CROSSING SOUTHERN CANADA.
WILL SEE A WARM UP WITH THE RIDGING COMING IN...AT LEAST BACK TO
NORMAL. DRY CONDITIONS SHOULD CONTINUE AS WELL WITH THE HIGH
PRESSURE OVER THE WEEKEND BLOCKING GULF OF MEXICO MOISTURE RETURN.
&&
.AVIATION...THROUGH 18Z WEDNESDAY
1217 PM CDT TUE SEP 4 2012
CHALLENGING FORECAST PERIOD WITH A COUPLE ROUNDS OF SHOWERS/STORMS
POSSIBLY AFFECTING KRST/KLSE OVER THE NEXT 24 HOURS. FIRST WAVE
ENTERING MINNESOTA AND COMBINED WITH STRONG SURFACE HEATING AND A
MOIST AIRMASS...SHOWERS/STORMS ARE EXPECTED TO FIRE UP ACROSS
EASTERN MINNESOTA BETWEEN 20 AND 22Z AND THEN QUICKLY TRACK
EAST/SOUTHEAST THROUGH AROUND OR SHORTLY AFTER 00Z. AT THIS
TIME...CONFIDENCE IS HIGHER THAT KLSE WILL BE IMPACTED AND HAVE
CONTINUED PRECIP MENTION STARTING 22Z THROUGH 00Z. AT
KRST...CONDITIONS SHOULD REMAIN VFR AS BULK OF STORMS ARE EXPECTED
TO BE EAST OF THE AIRPORT.
850 MB MOISTURE TRANSPORT REALLY RAMPS UP ACROSS SOUTHERN MINNESOTA
STARTING AFTER 06Z TONIGHT AHEAD OF A POTENT SHORTWAVE THAT WILL
MOVE ACROSS THE UPPER MIDWEST. CONFIDENCE HAS INCREASED THAT
STORMS WILL DEVELOP...MOST LIKELY IMPACTING KRST AFTER 06Z AND
THEN KLSE AFTER 09Z. A COLD FRONT WILL THEN SWEEP ACROSS THE AREA
BETWEEN 15 AND 18Z WEDNESDAY..BRINGING AN END TO PRECIP AND A
SHIFT TO NORTHERLY WINDS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
256 PM CDT TUE SEP 4 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...ZT
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1150 PM CDT MON SEP 3 2012
.SHORT TERM...TONIGHT THROUGH THURSDAY
256 PM CDT MON SEP 3 2012
MAIN FORECAST CONCERNS ARE ON PRECIPITATION CHANCES THROUGH
WEDNESDAY.
CURRENTLY AS OF 20Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED BROAD TROUGHING OVER SOUTHWEST AND SOUTH CENTRAL CANADA...
WITH NEARLY ZONAL FLOW ON ITS SOUTH SIDE ACROSS MUCH OF THE NORTHERN
U.S.. WITHIN THE BROAD UPPER TROUGHING...A PORTENT SHORTWAVE IS
EVIDENT OVER CENTRAL ALBERTA. IN THE ZONAL FLOW...THERE ARE NUMEROUS
WEAK SHORTWAVES...WHICH DURING THIS MORNING PRETTY MUCH ALL HAD AT
LEAST ACCAS OR CONVECTION WITH THEM: ONE IN NORTH DAKOTA...ANOTHER
IN WESTERN MINNESOTA...ONE IN WESTERN NEBRASKA AND LASTLY ONE IN
CENTRAL IOWA. DPVA AHEAD OF THE SHORTWAVE IN CENTRAL IOWA COMBINED
WITH A WEAKENING SURFACE COLD FRONT EXTENDING FROM CENTRAL UPPER
MICHIGAN TO NEAR DES MOINES...AS WELL AS MLCAPE VALUES THAT HAVE
CLIMBED TO 1500-2000 J/KG WITH LITTLE CIN PER RAP ANALYSIS...HAS
ALLOWED FOR SHOWER AND THUNDERSTORM DEVELOPMENT. MOST OF THE
ACTIVITY HAS BEEN DISORGANIZED...DUE TO 0-6KM SHEAR BELOW 30 KT
WHERE STORMS ARE IN THE FORECAST AREA. ALSO...A SURGE OF MONSOONAL
MID-CLOUDS THROUGH THE UPPER FLOW IS HELPING TO PUT A LID ON THE
AMOUNT OF INSTABILITY. THERE ARE EVEN SOME SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS COMING OUT OF THESE MID CLOUDS. WITH THE
VARYING CLOUD COVER AND PRECIPITATION...TEMPERATURES TODAY ARE ALL
OVER THE PLACE IN THE FORECAST AREA. MOST LOCATIONS REACHED
80...WHILE BOSCOBEL GOT CLOSE TO 90. ABNORMALLY HIGH DEWPOINTS
PERSIST TOO...WITH MOST OF THE AREA SEEING READINGS AROUND 70F.
TONIGHT AND TUESDAY...VERY TRICKY FORECAST TO SAY THE LEAST. THE
NEAR ZONAL FLOW WILL PERSIST THROUGH THIS PERIOD AS THE POTENT
ALBERT SHORTWAVE DIGS DOWN INTO THE NORTHERN PLAINS. MODELS CONTINUE
TO INDICATE WEAK SHORTWAVES MOVING THROUGH THIS FLOW...LIKE THOSE
AROUND THE DAKOTAS TODAY. WITH MUCAPE VALUES PROGGED TO NOT DROP
MUCH BELOW 1000 J/KG...HIGHLY CONCERNED THERE COULD BE OFF AND ON
SHOWERS AND THUNDERSTORMS THROUGHOUT THIS PERIOD. THIS HAS BEEN
SUGGESTED THE PAST FEW DAYS...ESPECIALLY BY THE ECMWF...THOUGH THE
LATEST 03.12Z ECMWF IS NOT AS ACTIVE. NOW SOME HI RESOLUTION MODEL
RUNS HAVE SUGGESTED THAT THE CURRENT AFTERNOON CONVECTION DROPS
SOUTHEAST THIS EVENING...WHILE OTHER CONVECTION DEVELOPS IN IOWA AND
DROPS SOUTHEAST. THIS ALLOWS THE FORECAST AREA TO END UP DRY AFTER
MIDNIGHT. FOR NOW HOLDING ON TO SOME LOW CHANCES OF PRECIPITATION
BECAUSE OF TOO MUCH UNCERTAINTY TO GO DRY BASED ON THE ENVIRONMENT.
IF SKIES CLEAR OUT TONIGHT...THE HIGH AMOUNT OF SURFACE MOISTURE
AROUND AND WEAK WIND FIELD WOULD LIKELY RESULT IN WIDESPREAD
RADIATION FOG. NOT ENTIRELY CONFIDENT WE WILL HAVE A LONG PERIOD OF
CLEAR SKIES...THOUGH. SO IN SUMMARY...THERE APPEARS TO BE TWO
SCENARIOS FOR TONIGHT:
1. SKIES CLEAR AND WE END UP WITH DENSE FOG
2. PERIODS OF ACCAS AND ISOLATED SHOWERS/STORMS
RIGHT NOW...BANKING ON NUMBER 2 AND ACKNOWLEDGING THE FOG BY ADDING
AT LEAST A PATCHY MENTION AFTER MIDNIGHT INTO TUESDAY MORNING. WITH
THE HIGH AMOUNT OF SURFACE MOISTURE...ANTICIPATING TEMPERATURES
OUTSIDE OF THE TYPICAL COLD SPOTS TO NOT DROP BELOW THE MID 60S.
DEPENDING ON AMOUNT OF SUN ON TUESDAY...WITH 850MB TEMPS BETWEEN
18-20C...HIGHS COULD GET CLOSE TO 90.
TUESDAY NIGHT AND WEDNESDAY...THE POTENT SHORTWAVE TROUGH COMING
INTO THE NORTHERN PLAINS AT 00Z WEDNESDAY IS FORECAST TO DIG INTO
MINNESOTA BY 12Z...THEN RAPIDLY SHOOT EAST OVER MUCH OF MICHIGAN BY
00Z THURSDAY. THIS RAPID MOVEMENT MEANS AN OVERALL SHORT TIME WINDOW
FOR PRECIPITATION FORCED BY THE TROUGH. NOTE THAT THE BEST 500-300MB
PV ADVECTION IS STILL SUGGESTED TO STAY TO THE NORTH OF THE FORECAST
AREA. HOWEVER...THE COMBINATION OF WEAK 500MB HEIGHT FALLS...A SURGE
OF LOW TO MID LEVEL MOISTURE TRANSPORT...AS WELL AS AT LEAST
1000-1500 J/KG OF MUCAPE ACCOMPANYING THE MOISTURE TRANSPORT SHOULD
PRODUCE SHOWERS AND THUNDERSTORMS ACROSS MUCH OF THE AREA. SOME OF
THESE COULD GET GOING AS EARLY AS THE EVENING...BUT BETTER CHANCES
ARE EXPECTED AFTER MIDNIGHT THROUGH ABOUT 15Z WEDNESDAY...WHEN THE
TROUGH IS HAVING ITS BIGGEST FORCING INFLUENCE. 1-6KM SHEAR IS
GENERALLY 15-25KT...WHICH SHOULD KEEP CONVECTION SUB-SEVERE. AFTER
15Z...STRONG SUBSIDENCE WILL WORK IN WEST TO EAST...CLEARING SKIES
OUT. WINDS SHOULD PICK UP TOO AS THE PRESSURE GRADIENT TIGHTENS...
COLD ADVECTION AND DEEP MIXING OCCUR. NOTING ABOUT THE COLD
ADVECTION...850MB TEMPS WHICH LOOK TO HOVER BETWEEN 16-20C TUESDAY
NIGHT END UP FALLING TO 12-14C OR SLIGHTLY COOLER BY 00Z WEDNESDAY.
THUS...EXPECT COOLER HIGHS FOR WEDNESDAY ON THE ORDER OF MID 70S TO
LOWER 80S. TUESDAY NIGHT WILL STILL BE WARM WITH LOWS IN THE
60S...THANKS TO SOUTH FLOW AHEAD OF THE SHORTWAVE/ASSOCIATED COLD
FRONT AND HIGHER DEWPOINTS.
WEDNESDAY NIGHT AND THURSDAY...IN THE WAKE OF WEDNESDAYS POTENT
SHORTWAVE...UPPER FLOW TURNS ZONAL OVER THE AREA. BUT THIS IS
BRIEF...WITH ATTENTION TURNING BACK TO ALBERTA WHERE YET ANOTHER
POTENT SHORTWAVE IS PROGGED TO DROP SOUTH INTO MONTANA BY 00Z
FRIDAY. WEDNESDAY NIGHT STILL LOOKS DRY THANKS TO LINGERING DRY AIR
AND SUBSIDENCE IN THE WAKE OF WEDNESDAYS TROUGH. THURSDAY IS A
LITTLE MORE PROBLEMATIC. TO THE NORTH...MODELS ARE INDICATING A
COUPLE OF SHORTWAVES CROSSING NORTHERN MINNESOTA AND WISCONSIN...
WHICH BRING DOWN A COLD FRONT INTO NORTHWEST WI BY 00Z. BOTH THE
03.12Z NAM AND 03.06Z GFS DEPICT SOME LIGHT QPF ACROSS TAYLOR COUNTY
WITH THIS FEATURE IN THE AFTERNOON. SOUNDINGS SUGGEST VERY LITTLE
MUCAPE WITH THIS FRONT AND A FAIRLY DRY BOUNDARY LAYER BELOW 750MB.
NEW 03.12Z GFS HAS CAME IN DRY. THEREFORE...HAVE HELD OFF ON MENTION
ANY PRECIPITATION CHANCES UP AROUND TAYLOR COUNTY. FOR THE REST OF
THE AREA...300-305K ISENTROPIC LIFT GRADUALLY INCREASES DURING THE
AFTERNOON...ALL KIND OF DOWNSTREAM OF THAT SHORTWAVE DROPPING INTO
MONTANA. SHOULD SEE SOME MID/HIGH CLOUDS DEVELOP AS A RESULT OF THIS
LIFT...BUT THINKING THE MAJORITY OF THESE CLOUDS ANY PRECIPITATION
POTENTIAL WITH THEM WILL STAY WEST/SOUTHWEST OF THE AREA. THIS
AGREES WELL WITH THE 03.12Z GFS/ECMWF. COOLER PERIOD ANTICIPATED.
MAY HAVE TO WATCH FOR VALLEY FOG POTENTIAL IF THE SURFACE RIDGE OF
HIGH PRESSURE COMING IN WEDNESDAY NIGHT BUILDS IN FASTER.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
256 PM CDT MON SEP 3 2012
THROUGH SATURDAY...MODELS REMAIN IN GOOD AGREEMENT WITH THE HANDLING
OF THE POTENT SHORTWAVE OVER MONTANA...HOW IT ENDS UP FORMING A
FAIRLY DEEP TROUGH OVER THE UPPER AND MID MISSISSIPPI RIVER VALLEYS
BY 12Z SATURDAY. AS THIS TROUGH FORMS...FRONTOGENESIS DOWNSTREAM
WILL LIKELY SPREAD MID/HIGH CLOUDS ACROSS THE AREA THURSDAY NIGHT
AND FRIDAY...SOME OF WHICH COULD PRODUCE A FEW SHOWERS. OVERALL...
BULK OF PRECIPITATION IS ANTICIPATED TO STAY TO THE SOUTH...CLOSER
TO A DEVELOPING LOW PRESSURE SYSTEM LIFTING OUT OF THE CENTRAL
PLAINS. BY FRIDAY NIGHT...AS THE TROUGHING MOVES IN...THE CLOUDS AND
POTENTIAL FOR SHOWERS GET PUSHED EAST. HIGH PRESSURE THEN BUILDS IN
FOR SATURDAY. MUCH OF THIS PERIOD THROUGH SATURDAY WILL BE BELOW
NORMAL...DUE TO FIRST CLOUDS ON FRIDAY AND THEN 850MB TEMPS FALLING
TO 6-8C FOR SATURDAY. HIGHS MAY STRUGGLE TO CLIMB TO OR MUCH ABOVE
70.
BEYOND SATURDAY...MODELS HANDLE THE TROUGHING DIFFERENTLY...WITH THE
03.12Z ECMWF AND CANADIAN CLOSING IT OFF AND PERHAPS MOVING IT
SOUTHEAST...WHEREAS THE 03.12Z GFS AND ITS ENSEMBLES REMAIN MORE
PROGRESSIVE. FOR THE FORECAST AREA...EITHER SCENARIO DOESNT MATTER
MUCH...AS ALL MODELS END UP HAVING UPPER RIDGING BUILDING UP OVER
THE PLAINS AND INTO THE FORECAST AREA LATE MONDAY. THIS WILL KEEP
CONDITIONS DRY WITH A GRADUAL WARMING TREND. BY MONDAY...850MB TEMPS
ARE BACK UP TO 12-14C...YIELDING HIGHS AT LEAST AROUND NORMAL.
&&
.AVIATION...THROUGH 06Z WEDNESDAY
1150 PM CDT MON SEP 3 2012
RATHER COMPLICATED FORECAST SCENARIO FOR THIS TAF CYCLE. INFRARED
SATELLITE IMAGERY SHOWING A BAND OF CLEARING WORKING ITS WAY INTO
SOUTHEAST MINNESOTA. VISIBILITIES HAVE ALREADY DROPPED TO 2 1/2 MILES
AT KRST AND EXPECT VISIBILITIES TO DROP INTO THE IFR CATEGORY AT
KRST AT TAF ISSUANCE TIME AND INTO THE MVFR CATEGORY AT KLSE A FEW
HOURS LATER. QUESTION WILL BE HOW FAR THEY DROP BEFORE MID AND HIGH
LEVEL CLOUDS FROM THE CONVECTION OVER THE DAKOTAS MAKES IT WAY
OVERHEAD. HAVE INCLUDED A TEMPO 1/4SM AT KRST AND 1SM AT KLSE AS
CONDITIONS LOOKS FAVORABLE TO SEE AT LEAST SOME IFR CONDITIONS FOR
A WHILE AND CANNOT RULE OUT A PERIOD OF DENSE FOG AS WELL AT KSLE.
AFTER ANY FOG LIFTS TUESDAY MORNING...THE NEXT SHORTWAVE WILL
APPROACH THE AREA. THE 03.21Z SREF INCREASES PROBABILITIES DURING
THE AFTERNOON HOURS...ESPECIALLY EAST OF THE MISSISSIPPI RIVER.
THIS CONSISTENT WITH INCREASING MOISTURE TRANSPORT AND AN UNSTABLE
AIR MASS. DID MENTION SHRA AT KLSE AND JUST VCSH AT KRST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
256 PM CDT MON SEP 3 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...JLR
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
137 AM EDT THU SEP 6 2012
.AVIATION...
COLD FRONT WILL CROSS THE AREA LATER THIS MORNING BUT ABUNDANT
DRY AND STABLE AIR IS PREVENTING ANY SHOWERS FROM DEVELOPING.
CLEAR SKIES AND LIGHT WINDS ARE CAUSING SOME PATCHY FOG TO DEVELOP
ACROSS THE AREA. NOT EXPECTING DENSE FOG BUT MVFR VISIBILITIES
WILL BE POSSIBLE AT KFWA DURING THE NEXT FEW HOURS.
OTHERWISE...VFR CONDITIONS WILL PERSIST TODAY WITH SOME AFTERNOON
CU BASED AROUND 4-5 KFT. NORTHWEST WINDS WILL ALSO INCREASE TODAY
BEHIND THE COLD FRONT.
&&
.PREV DISCUSSION... /ISSUED 800 PM EDT WED SEP 5 2012/
UPDATE...
STABLE POST OUTFLW BUBBLE HAS CURTAILED ANY UPSTREAM
CONV DVLPMNT WITHIN RTN LL THETA-E WEDGE ACRS ERN IA/WRN-NRN IL
THIS EVENING AHD OF CDFNT AND DOUBT THAT WILL CHG GOING FORWARD
THROUGH TONIGHT. DROPPED PRIOR TRIMMED POPS FM AFTN ISSUANCE
FORWARD AND MAY DROP ENTIRELY ONCE DVN/ILX 00Z RAOBS ARRIVE. THUS
ITS MORE LIKELY CDFNT COMES THROUGH DRY LTR TONIGHT.
&&
SHORT TERM...
TONIGHT THROUGH THURSDAY NIGHT.
SHORT/SMALL WINDOW OF OPPORTUNITY WRT DESTABILIZATION INADV SFC
FNTL BNDRY ACRS XTRM SERN WI/NRN IL/ERN IA/MO LATE THIS AFTN. OF
NOTE HAS BEEN SPC RAP FAILURE TO ADEQUATELY ASSESS DOWNSTREAM
STABILIZATION AMID WAKE OF MATURE BUBBLE MESOHIGH BEHIND LATE
AM/ERLY AFTN LINEAR CONVECTION THAT NOW ARCHES FM NRN OH TO OH RVR
VALLEY. WHILE EWD ADVANCE OF STEEP 7-5H LAPSE RATES OF 8-9 C/KM
OMINOUS...THE CERTAINLY FAR FROM PRISTINE 0-3KM THERMODYNAMIC
ENVIRON ACRS NERN IL/CWA AMID DENSE CONVECTIVE DEBRIS AND WELL
OVERTURNED ATMOS...WL LKLY QUELL ALL BUT JUST A FLEETING HOPE FOR
ANY FIRM CONVECTIVE MAINTENANCE WITH ERN EXTENT. GIVEN
CONDITIONALITY WRT LATE AFTN INITIATION WITH MODEST LLVL WIND
PROFILE/LWST 100 MB CONVERGENCE AHEAD OF FNT...AND ADDED
CONDITIONALITY FURTHER DOWNSTREAM...HAVE CHOSE LOWER END GUID WITH
NO HIER THAN MID RANGE CHC POPS AFT 02 UTC. SEVERE RISK ALSO
APPEARS TO BE WANING...BUT WL LET HWO CONTINUE TO COVER WITH HIEST
RISKS ACRS SRN CWA/ALONG PROGGED OVERLAP OF SFC CAPE RESERVOIR
AND MODERATE DEEP LYR SHEAR/INCRSG THIS EVE AS 50 KT 5H WNWLY FLOW
ACRS IL/WI SURGES EWD. NIL WX AFTER TONIGHT IN DRYING LLVL ATMOS.
HAVE LWRD TEMPS INVOF KBEH SUBSTANTIALLY TMWR NIGHT IN WEAKENING
SFC FLOW AS 1018 MB PLAINS HIGH SETTLES ACRS SRN GRTLKS...FAVORING
COOL DRAINAGE ALONG LAKESHORE NEAR DAYBREAK FRI.
&&
LONG TERM...
FRIDAY THROUGH WEDNESDAY...A SIGNIFICANT TROF WILL MOVE ACROSS THE
WESTERN GREAT LAKES REGION EARLY IN THE PERIOD. BOTH THE GFS AND THE
ECMWF HAVE ABANDONED THE EARLY CUT OFF LOW SOLUTION FROM MANY
PREVIOUS RUNS IN LIEU OF A MORE PROGRESSIVE OPEN WAVE SOLUTION DUE
TO MORE PHASING WITH THE NORTHERN STREAM AND THE APPROACH OF ANOTHER
UPSTREAM UPPER TROF. HOWEVER...THE ONGOING TIMING OF THE ARRIVAL OF
THE MAIN TROF OVER THE WESTERN GREAT LAKES REGION STILL APPEARS ON
TRACK WITH THE BEST CHANCE FOR RAIN FRIDAY NIGHT. KEPT SHOWERS
LIKELY FRIDAY NIGHT. ADDED A CHANCE FOR THUNDER SOUTHEAST HALF PER
ECMWF WITH EMBEDDED STORMS POSSIBLE GIVEN MOISTURE AND LIFT
AVAILABLE. OTHERWISE...COOLER AND DRY CONDITIONS SUNDAY AND MONDAY
FOLLOWED BY A RETURN TO ABOVE NORMAL TEMPERATURES WEDNESDAY AND THE
UPPER LEVEL RIDGE BUILDS EAST AHEAD OF THE NEXT UPPER LEVEL TROF CAN
BE EXPECTED. THE 500 MB CANADIAN AND GFS ANALOGS ALSO SUPPORT
TEMPERATURES RISING ABOVE NORMAL.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...RIP CURRENT RISK FROM 7 AM CDT THIS MORNING THROUGH THIS EVENING
FOR INZ003.
MI...RIP CURRENT RISK FROM 8 AM EDT THIS MORNING THROUGH THIS EVENING
FOR MIZ077.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...MURPHY
LONG TERM...SKIPPER
AVIATION...AGD
UPDATE...T
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
359 AM CDT THU SEP 6 2012
.SHORT TERM...
ISSUED AT 332 AM CDT THU SEP 6 2012
(TODAY THROUGH FRIDAY NIGHT)
STILL EATING CROW AFTER YESTERDAY`S BUSTED FORECAST...AND IT`S A
BITTER BIRD. THE COLD FRONT HAS MADE IT THROUGH KIRKSVILLE BUT IS
TAKING ITS TIME DRIFTING THROUGH THE NORTHWEST PORTION OF THE CWFA.
CURRENT THINKING IS THAT THE FRONT WILL CONTINUE DRIFTING SOUTHEAST
BUT WILL PROBABLY NOT CLEAR THE SOUTHERN PORTION OF THE CWFA BEFORE
AFTERNOON. RAP AND HRRR DEVELOP DECENT INSTABILITY IN EXCESS OF
2000 J/KG WITH LITTLE OR NO CAP. HAVE ADDED POPS SOUTH OF THE STL
METRO AREA ACROSS THE EASTERN OZARKS. ALSO...SINCE THE COLD AIR
ADVECTION IS SOMEWHAT LACKING FROM PREVIOUS FORECASTS...HAVE BUMPED
UP TEMPS A COUPLE OF DEGREES TODAY.
ATTENTION TURNS TO THE STRONG SHORTWAVE JUST NOW DROPPING INTO THE
CONUS FROM SOUTHEAST CANADA AND THE RESULTING STORM WHICH WILL MOVE
THROUGH FRIDAY AND FRIDAY NIGHT. THE WAVE`S PRESENTATION ON WATER
VAPOR IMAGERY IS PRETTY IMPRESSIVE FOR EARLY SEPTEMBER. THIS IS
ENCOURAGING FOR THE FORECAST. LATEST GUIDANCE KEEPS MUCH OF THE
AREA DRY TONIGHT...PRETTY MUCH ALL EXCEPT NORTHEAST MISSOURI AND
WEST CENTRAL ILLINOIS. CAN`T QUITE BRING MYSELF TO PULL POPS OUT OF
THE REST OF THE AREA THO...SO HAVE LEFT THEM BE. ALL GUIDANCE HAS
THE SHORTWAVE DIVING INTO THE PLAINS FRIDAY MORNING AND THE
ASSOCIATED COLD FRONT MOVING THROUGH KIRKSVILLE BY AROUND 18Z. SPC
HAS US OUTLOOKED IN A SLIGHT RISK AND THIS LOOKS GOOD GIVEN THAT THE
NAM DEVELOPS INSTABILITY IN EXCESS OF 3000 J/KG AND PLENTY OF DEEP
LAYER SHEAR. HAVE BUMPED UP POPS TO OCCASIONAL DURING THE AFTERNOON
AND EARLY EVENING FOR PARTS OF THE AREA. LATEST GUIDANCE HAS THE
FRONT MOVING THOUGH FASTER THAN EARLIER FORECAST...SO HAVE CUT BACK
ON POPS AFTER MIDNIGHT.
CARNEY
&&
.LONG TERM...
ISSUED AT 358 AM CDT THU SEP 6 2012
(SATURDAY THROUGH WEDNESDAY)
PRIMARY CHANGE TO THE FORECAST FOR THE LONG TERM IS TO INCREASE HIGH
TEMPERATURES A BIT THIS WEEKEND AND EARLY NEXT WEEK. ALL OF THE
MODELS DROP A STRONG RIDGE INTO THE AREA THIS WEEKEND BEHIND THE
FRONT. WHEN WE INITIALLY BEGAN SEEING THIS STORM SYSTEM IN THE
MODELS SEVERAL DAYS AGO...THEY DEVELOPED A CLOSED LOW OVER THE GREAT
LAKES/OHIO VALLEY REGION. THE PAST FEW RUNS THE MODELS HAVE BECOME
PROGRESSIVE WITH THE WAVE. THIS SHOULD MEAN THAT INSTEAD OF
CONSIDERABLE CLOUDS AND WIDELY SCATTERED SHOWERS ON SATURDAY...IT
SHOULD BE MOSTLY SUNNY AND DRY. WITH THE MORE PROGRESSIVE
SOLUTION...THE WARM UP BACK TO NEAR NORMAL TEMPERATURES SHOULD OCCUR
MORE QUICKLY ON SUNDAY INTO EARLY NEXT WEEK. UPPER LEVEL RIDGE
BUILDS BACK INTO THE AREA BY TUESDAY. ANOTHER COLD FRONT LOOKS TO
BE APPROACHING THE AREA ON WEDNESDAY...BUT HAVE NOT PUT ANY POPS IN
THE FORECAST AT THIS TIME AS THE STRONG SURFACE RIDGE WHICH WILL
BRING US THIS WEEKEND`S COOL WEATHER LOOKS LIKE IT WILL LAY OUT DOWN
ACROSS THE SOUTHERN U.S. AND BLOCK ANY MOIST RETURN FLOW FROM THE
GULF.
CARNEY
&&
.AVIATION...
ISSUED AT 1205 AM CDT WED SEP 5 2012
ILL-DEFINED COLD FRONT HAS BEEN MOVING AT AN AGONIZINGLY SLOW
PACE THIS EVENING AND APPEARS TO HAVE JUST MOVED INTO OUR NW
COUNTIES OVER THE PAST FEW HOURS. FROPA SHOULD OCCUR AT BOTH UIN
AND COU IN THE 06-08Z TIME FRAME...AND EVENTUALLY ADVECT DRIER AIR
INTO THES AREAS. MEANWHILE...RESIDUAL MOISTURE AND RAIN-COOLED
AIRMASS HAS BEGUN TO PRODUCE FOG IN THE STL METRO AREA...AND DUE
TO THE SLOW MOVEMENT OF THE FRONT THINK THAT THIS PATCHY FOG WILL
PERSIST UNTIL AT LEAST DAYBREAK. VSBY TRENDS FOR LOW LYING
AIRPORTS (SET/SUS/CPS) HAVE BEEN TO VFR-IFR AND BACK DURING THE PAST
90 MINUTES...AND BELIEVE THESE WILD SWINGS WILL CONTINUE AT THESE
LOCATIONS DUE TO THE WAY ASOS VSBYS ARE MEASURED UNTIL DRIER AIR
ARRIVES...WHICH SHOULD BE IN THE 12-14Z TIME FRAME. CLEAR SKIES
AND LIGHT N-NE WINDS SHOULD BE THE RULE THROUGHOUT THE DAY ON
THURSDAY.
SPECIFICS FOR KSTL...
WHILE FOG WITH OCCASIONAL IFR VSBYS SHOULD HAVE ITS BIGGEST
IMPACT ON AFOREMENTIONED LOW LYING AIRPORTS (SUS/CPS)...HAVE ADDED
SOME LIGHT FOG WITH MVFR VSBYS TO STL DURING THE PREDAWN HOURS. NW
WINDS SHOULD INCREASE AROUND 12-13Z...DRAGGING DRIER AIR INTO THE
REGION AND DISSIPATING ANY LINGERING FOG.
TRUETT
&&
.PRELIMINARY POINT TEMPS/POPS...
ST LOUIS 91 71 85 58 / 5 30 80 70
QUINCY 86 66 78 53 / 5 60 70 40
COLUMBIA 91 69 80 54 / 10 50 80 40
JEFFERSON CITY 91 69 83 56 / 10 40 80 50
SALEM 89 67 85 59 / 5 20 80 80
FARMINGTON 92 69 85 58 / 20 20 80 80
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
333 AM CDT THU SEP 6 2012
.SHORT TERM...
ISSUED AT 332 AM CDT THU SEP 6 2012
(TODAY THROUGH FRIDAY NIGHT)
STILL EATING CROW AFTER YESTERDAY`S BUSTED FORECAST...AND IT`S A
BITTER BIRD. THE COLD FRONT HAS MADE IT THROUGH KIRKSVILLE BUT IS
TAKING ITS TIME DRIFTING THROUGH THE NORTHWEST PORTION OF THE CWFA.
CURRENT THINKING IS THAT THE FRONT WILL CONTINUE DRIFTING SOUTHEAST
BUT WILL PROBABLY NOT CLEAR THE SOUTHERN PORTION OF THE CWFA BEFORE
AFTERNOON. RAP AND HRRR DEVELOP DECENT INSTABILITY IN EXCESS OF
2000 J/KG WITH LITTLE OR NO CAP. HAVE ADDED POPS SOUTH OF THE STL
METRO AREA ACROSS THE EASTERN OZARKS. ALSO...SINCE THE COLD AIR
ADVECTION IS SOMEWHAT LACKING FROM PREVIOUS FORECASTS...HAVE BUMPED
UP TEMPS A COUPLE OF DEGREES TODAY.
ATTENTION TURNS TO THE STRONG SHORTWAVE JUST NOW DROPPING INTO THE
CONUS FROM SOUTHEAST CANADA AND THE RESULTING STORM WHICH WILL MOVE
THROUGH FRIDAY AND FRIDAY NIGHT. THE WAVE`S PRESENTATION ON WATER
VAPOR IMAGERY IS PRETTY IMPRESSIVE FOR EARLY SEPTEMBER. THIS IS
ENCOURAGING FOR THE FORECAST. LATEST GUIDANCE KEEPS MUCH OF THE
AREA DRY TONIGHT...PRETTY MUCH ALL EXCEPT NORTHEAST MISSOURI AND
WEST CENTRAL ILLINOIS. CAN`T QUITE BRING MYSELF TO PULL POPS OUT OF
THE REST OF THE AREA THO...SO HAVE LEFT THEM BE. ALL GUIDANCE HAS
THE SHORTWAVE DIVING INTO THE PLAINS FRIDAY MORNING AND THE
ASSOCIATED COLD FRONT MOVING THROUGH KIRKSVILLE BY AROUND 18Z. SPC
HAS US OUTLOOKED IN A SLIGHT RISK AND THIS LOOKS GOOD GIVEN THAT THE
NAM DEVELOPS INSTABILITY IN EXCESS OF 3000 J/KG AND PLENTY OF DEEP
LAYER SHEAR. HAVE BUMPED UP POPS TO OCCASIONAL DURING THE AFTERNOON
AND EARLY EVENING FOR PARTS OF THE AREA. LATEST GUIDANCE HAS THE
FRONT MOVING THOUGH FASTER THAN EARLIER FORECAST...SO HAVE CUT BACK
ON POPS AFTER MIDNIGHT.
CARNEY
&&
.AVIATION...
ISSUED AT 1205 AM CDT WED SEP 5 2012
ILL-DEFINED COLD FRONT HAS BEEN MOVING AT AN AGONIZINGLY SLOW
PACE THIS EVENING AND APPEARS TO HAVE JUST MOVED INTO OUR NW
COUNTIES OVER THE PAST FEW HOURS. FROPA SHOULD OCCUR AT BOTH UIN
AND COU IN THE 06-08Z TIME FRAME...AND EVENTUALLY ADVECT DRIER AIR
INTO THES AREAS. MEANWHILE...RESIDUAL MOISTURE AND RAIN-COOLED
AIRMASS HAS BEGUN TO PRODUCE FOG IN THE STL METRO AREA...AND DUE
TO THE SLOW MOVEMENT OF THE FRONT THINK THAT THIS PATCHY FOG WILL
PERSIST UNTIL AT LEAST DAYBREAK. VSBY TRENDS FOR LOW LYING
AIRPORTS (SET/SUS/CPS) HAVE BEEN TO VFR-IFR AND BACK DURING THE PAST
90 MINUTES...AND BELIEVE THESE WILD SWINGS WILL CONTINUE AT THESE
LOCATIONS DUE TO THE WAY ASOS VSBYS ARE MEASURED UNTIL DRIER AIR
ARRIVES...WHICH SHOULD BE IN THE 12-14Z TIME FRAME. CLEAR SKIES
AND LIGHT N-NE WINDS SHOULD BE THE RULE THROUGHOUT THE DAY ON
THURSDAY.
SPECIFICS FOR KSTL...
WHILE FOG WITH OCCASIONAL IFR VSBYS SHOULD HAVE ITS BIGGEST
IMPACT ON AFOREMENTIONED LOW LYING AIRPORTS (SUS/CPS)...HAVE ADDED
SOME LIGHT FOG WITH MVFR VSBYS TO STL DURING THE PREDAWN HOURS. NW
WINDS SHOULD INCREASE AROUND 12-13Z...DRAGGING DRIER AIR INTO THE
REGION AND DISSIPATING ANY LINGERING FOG.
TRUETT
&&
.PRELIMINARY POINT TEMPS/POPS...
ST LOUIS 91 71 85 58 / 5 30 80 70
QUINCY 86 66 78 53 / 5 60 70 40
COLUMBIA 91 69 80 54 / 10 50 80 40
JEFFERSON CITY 91 69 83 56 / 10 40 80 50
SALEM 89 67 85 59 / 5 20 80 80
FARMINGTON 92 69 85 58 / 20 20 80 80
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
437 AM CDT THU SEP 6 2012
.UPDATE...
.FIRE WEATHER...
THE RFW PRODUCT HAS BEEN UPDATED FOR A WIND SHIFT DEVELOPING
AROUND 18Z PER RAP AND HRRR MODELS. THOSE MODELS ARE CONSOLIDATING
LOW PRESSURE ALONG THE ND/SD BORDER AND SENDING A "COLD" FRONT
INTO NRN NEB. THIS IS ABOUT 3 HOURS FASTER THAN THE OTHER OPERATIONAL
MODELS.
&&
.PREV DISCUSSION... /ISSUED 350 AM CDT THU SEP 6 2012/
DISCUSSION...
PRIMARY FORECAST CONCERNS FOR THIS FORECAST ARE FIRE WEATHER
CONCERNS TODAY...HIGHS TODAY...AS WELL AS TEMPERATURES AND RAIN
CHANCES SURROUNDING FRONTAL PASSAGE FRIDAY.
UPPER LEVEL ANALYSIS SHOWED LOW PRESSURE OVER NORTHERN
MANITOBA...WITH ONE SHORTWAVE TROUGH EXTENDING INTO THE GREAT
LAKES...AND A SECOND SHORTWAVE TROUGH EXTENDING INTO THE PACIFIC
NORTHWEST. THIS SECOND SYSTEM IS SHOWING THE STRONGEST ENERGY OVER
SOUTHERN BRITISH COLUMBIA MOVING INTO IDAHO AND MONTANA EARLY THIS
MORNING. ALSO...BROAD RIDGING SEEN ALOFT OVER THE SOUTHERN US.
THIS PATTERN LEADS TO FAIRLY ZONAL/NORTHWEST FLOW INTO THE LOCAL
FORECAST AREA CURRENTLY. THIS FLOW IS BRINGING A GOOD AMOUNT OF
SMOKE INTO THE CENTRAL PLAINS FROM FIRES OVER IDAHO AND WYOMING.
AT THE SURFACE...LOW PRESSURE OBSERVED OVER NORTHWEST SOUTH DAKOTA
WITH A COLD FRONT EXTENDING ACROSS NORTHERN WYOMING AND INTO
WESTERN MONTANA. ALSO...A SURFACE TROUGH WAS SEEN FROM WESTERN
SOUTH DAKOTA INTO THE NEBRASKA PANHANDLE...WITH THE AXIS OF HIGH
PRESSURE FROM NORTHWEST KANSAS INTO NORTHEAST NEBRASKA. UNDER THE
SURFACE HIGH...TEMPERATURES HAD DROPPED INTO THE 40S...WHILE
CLOSER TO THE TROUGH WHERE THE BOUNDARY LAYER HAD STAYED
MIXED...UPPER 60S WERE BEING OBSERVED.
SHORT TERM...TODAY THROUGH SATURDAY NIGHT
THE SHORTWAVE TROUGH OVER IDAHO/MONTANA WILL MOVE SOUTHEAST
ACROSS THE NORTHERN ROCKIES TODAY. THIS WILL KEEP THE FLOW QUITE
FLAT ACROSS THE CENTRAL AND NORTHERN PARTS OF THE COUNTRY...SO
WILL EXPECT TO CONTINUE TO SEE QUITE A BIT OF SMOKE IN THE SKY
THROUGH THE DAY TOMORROW. AS THE UPPER LEVEL SYSTEM MOVES
SOUTH...SO WILL THE COLD FRONT CURRENTLY OVER WYOMING. AHEAD OF
THE FRONT...THE SURFACE TROUGH/DRYLINE OVER THE NEBRASKA PANHANDLE
WILL SURGE EAST BRINGING VERY DRY AIR INTO THE FORECAST AREA. THE
NAM HAS BEEN PERFORMING BEST LATELY IN TERMS OF DEWPOINTS SO FELT
CONFIDENT IN GOING TOWARDS THAT MODEL FOR THE FORECAST TODAY. THIS
WOULD BRING 20 DEGREE DEWPOINTS INTO THE WESTERN PARTS OF THE
FORECAST AREA...WHICH LOOKS REASONABLE AS MUCH OF WYOMING AND
NORTHERN COLORADO ARE OBSERVING VALUES IN THE TEENS CURRENTLY.
THIS DRY AIR WILL HELP TO CREATE DEEP MIXING THIS AFTERNOON...AND
WHEN COMBINED WITH WARM AIR ADVECTION WITH THE HIGH MOVING OFF TO
THE EAST WENT ON THE HIGH END FOR TEMPERATURES TODAY. ALSO...HAVE
BEEN OBSERVING VERY LARGE DIURNAL SWINGS IN TEMPERATURES...SO
ALTHOUGH LOWS WILL BE IN THE 40S FOR SOME PLACES...DON/T SEE A
PROBLEM WITH REACHING THE MID 90S THIS AFTERNOON. PLACES OVER
NORTHWEST NEBRASKA WILL BE A BIT MORE TRICKY FOR HIGH TEMPERATURES
AS THE FRONT WILL PASS THROUGH THESE AREAS THIS AFTERNOON.
ALTHOUGH WILL LIKELY NOT SEE AS HOT OF TEMPERATURES IN THOSE
LOCATIONS...NOT GOING TO SEE THE COLD AIR PUSH INTO NEBRASKA
UNTIL EVENING AND OVERNIGHT SO STILL EXPECTING HIGHS IN THE UPPER
80S. BREEZY WINDS AND ALONG WITH A WINDSHIFT WITH THE
FRONT...COMBINED WITH THE HEAT AND VERY DRY CONDITIONS FIRE
WEATHER CONDITIONS WILL BE OF HIGH CONCERN. SEE DETAILED
DISCUSSION BELOW.
CONTINUED THE SLIGHT CHANCES FOR THUNDERSTORMS IN THE FAR EASTERN
COUNTIES LATER THIS AFTERNOON AND EVENING AS DEVELOPMENT IS
EXPECTED ALONG AND EAST OF THE DRYLINE. PROBABILITIES ARE BEST
EAST OF THE FORECAST AREA...BUT IF THE DRY AIR DOESN/T ADVANCE AS
FAR EAST...THE AREA OF CONCERN WILL SHIFT. ANY STORMS THAT DO
DEVELOP ON THIS LINE WILL HAVE THE POTENTIAL TO BE STRONG TO
SEVERE WITH FAVORABLE SHEAR AND INSTABILITY EXPECTED.
TONIGHT...BREEZY CONDITIONS ARE EXPECTED AS THE FRONT PUSHES
SOUTH. ALTHOUGH COLDER AIR WILL BE PUSHING IN BEHIND THE
FRONT...THE WINDS AND GOOD AMOUNT OF CLOUD COVER WILL PROHIBIT
TEMPERATURES FROM FALLING TOO MUCH. ALSO...THERE WILL BE CHANCES
FOR RAIN TONIGHT. AREAS WITH THE HIGHER CHANCE FOR RAIN WILL BE
OVER NORTHERN NEBRASKA AFTER MIDNIGHT AS STRONGER LIFT WILL BE
OVER THE AREA AT THAT TIME...WITH THE FRONT AND THE UPPER LEVEL
ENERGY PUSHING THROUGH. THESE CHANCES WILL SHIFT SOUTH FRIDAY
MORNING...HOWEVER DYNAMICS DOESN/T LOOK AS GOOD SO ONLY HAVE A
SLIGHT CHANCE THROUGH 18Z ACROSS THE FORECAST AREA. ALTHOUGH
DYNAMICALLY...IT LOOKS FAVORABLE FOR SHOWERS...LOW LEVEL MOISTURE
WILL BE A LIMITING FACTOR. THE NAM IS SHOWING MOISTURE IMPROVING
WITH PRECIPITABLE WATER INCREASING TO NEAR AN INCH ALONG THE
FRONT...BUT DON/T KNOW IF THERE WILL BE THAT MUCH MOISTURE
ADVECTION BETWEEN NOW AND THEN. LATEST KLBF SOUNDING HAD PW OF
0.38 INCHES. CROSS-SECTIONS ALSO SUGGESTING THE COLUMN WILL NEARLY
SATURATE. DON/T WANT TO DISCOUNT THIS...BUT LOOKING AT THIS SYSTEM
OVER MONTANA CURRENTLY...MOST CEILINGS ARE ABOVE 5K FEET. WILL
CONTINUE TO WATCH THE SYSTEM CLOSELY...BUT FEELING IS ANY RAINFALL
WILL BE LIGHT WITH LITTLE ACCUMULATIONS /LESS THAN A TENTH OF AN
INCH/ EXPECTED.
WITH THE CLOUDY SKIES AND COLD AIR MOVING INTO THE AREA BEHIND THE
FRONT...FRIDAY SHOULD BE A MUCH COOLER DAY. LOOKING AT HIGHS ONLY
IN THE UPPER 60S AND 70S. HOWEVER...BIG STORY WILL BE LOWS FRIDAY
NIGHT. WITH HIGH PRESSURE SETTLING IN...SKIES SHOULD CLEAR AND
WINDS ARE EXPECTED TO BECOME LIGHT OR CALM. THESE CONDITIONS WILL
PROMOTE RADIATIONAL COOLING...AND WITH THE DRY AIRMASS IN PLACE
/DEWPOINTS IN THE 30S/...EXPECT A COLD NIGHT ACROSS WESTERN
NEBRASKA. DROPPED LOWS TEMPERATURES...WITH LOCATIONS IN VALLEYS OR
OTHER FAVORED DRAINAGE AREAS FALLING INTO THE 30S. WILL BE CLOSELY
WATCHING THIS IN COMING FORECASTS AS LOWS IN THE 30S COULD MEAN
THE DEVELOPMENT OF FROST IN AREAS.
LOOKING TO SATURDAY...HIGH PRESSURE WILL CONTINUE TO INFLUENCE THE
AREA. HOWEVER...WARM AIR ADVECTION WILL BE ONGOING ALOFT. GOOD
MIXING AND SUNSHINE WILL ALLOW FOR TEMPERATURES TO WARM BACK TO
NEAR NORMAL VALUES AROUND 80 DEGREES.
LONG TERM...SUNDAY THROUGH WEDNESDAY
TEMPERATURES WILL BE ON THE RISE SUNDAY AND MONDAY...WITH
POTENTIAL SHOWING UP FOR ANOTHER HOT DAY ON MONDAY. HAVE LOW 90S
IN THE FORECAST CURRENTLY BUT MAY NEED TO ADJUST THOSE NUMBERS UP
IN COMING FORECASTS. ANOTHER COLD FRONT IS PROJECTED TO MOVE
THROUGH THE FORECAST AREA ON TUESDAY. TIMING IS A BIT PROBLEMATIC
AT THIS TIME...WHICH WILL HAVE IMPACT ON TEMPERATURES FOR TUESDAY.
ANOTHER PUSH OF COLD AIR WILL COME INTO THE AREA BEHIND THIS
FRONT...SO WEDNESDAY IS LOOKING TO BE A DAY WITH HIGHS IN THE 70S.
IN TERMS OF RAINFALL...THE FORECAST REMAINS DRY AS MODELS ARE
SHOWING DRY AIR CONTINUING TO BE DOMINANT SO DON/T HAVE A GOOD
HANDLE IF ANY SHOWERS/STORMS WILL DEVELOP ALONG THE FRONT.
CONSENSUS FROM THE CURRENT MODELS INDICATES THE FRONT WILL PASS BY
DRY FOR THE MOST PART WITH MAYBE A FEW ISOLATED STORMS.
WILL CONTINUE TO KEEP THE FORECAST DRY UNLESS MODELS START SHOWING
BETTER SIGNALS FOR PRECIPITATION DEVELOPMENT.
AVIATION...
VFR IS EXPECTED ALL AREAS THROUGH 06Z THIS EVENING.
06Z-12Z TONIGHT...THEREAFTER A STRONG COLD FRONT MAY BE SUFFICIENT
FOR MVFR CIGS AND LIGHT RAIN ALONG AND NORTH OF NEBRASKA HIGHWAY 2.
LATER FORECASTS CAN VERIFY THE RELIABILITY OF THIS FCST AS LOW LEVEL
MOISTURE MAY BE A LIMITING FACTOR.
FIRE WEATHER...
ARF...NMM AND NAM SOLNS SHOW RH FALLING TO BETWEEN 5 AND 7 PERCENT
ACROSS WRN NEB. THE OFFICIAL FORECAST IS FOR 8 TO 10 PERCENT RH AND
WIND GUSTS TO AROUND 30 MPH. THUS A BIG FIRE DAY IS EXPECTED. DPTS
ACROSS WY ARE IN THE TEENS WITH RH AS LOW AS 18 PERCENT AT LANDER
AND RIVERTON AT 07Z.
A RED FLAG WARNING IS IN EFFECT FOR ALL ZONES TODAY.
OTHER OPPORTUNITIES FOR CRITICAL FIRE DANGER COULD DEVELOP SUNDAY
ACROSS THE WRN HIGH PLAINS AS LOW PRESSURE DEEPENS ACROSS THE NRN
HIGH PLAINS. ALSO MONDAY COULD BE A BIG FIRE DAY FOR ALL AREAS AS A
LOW PRESSURE TROF MOVES EAST THROUGH THE CNTL AND NRN PLAINS.
CONCERNS CONTINUE TUESDAY AS DRY AIR WILL BE MOVING SWIFTLY SOUTH
BEHIND A COLD FRONT PROGGED TO MOVE THROUGH MONDAY NIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING FROM NOON CDT /11 AM MDT/ TODAY TO 10 PM CDT /9
PM MDT/ THIS EVENING FOR NEZ204-206-208>210-219.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
337 AM EDT THU SEP 6 2012
.SYNOPSIS...
WEAK COLD FRONT ARRIVES THIS EVENING. HIGH PRESSURE FRIDAY. STRONG
COLD FRONT SATURDAY. HIGH PRESSURE SUNDAY INTO THE NEXT WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE...
SHRA CONT TO INCREASE ACROSS N CARTER AND S GREENUP AS OF
0630Z...WITH NEARLY STATIONARY MOTIONS. BUMPED UP POPS INTO LKLY
NEXT COUPLE HRS ACROSS NE KY COUNTIES. WILL BE MONITORING RAINFALL
AS WELL.
PREVIOUS DISCUSSION BELOW...
SHRA LIGHTING UP ON RADAR AT 06Z ACROSS W ZONES...ASSOCIATED WITH
S/W TROF AND EMBEDDED VORT MAX. RUC TRACKS THIS SLOWLY NE THRU CWA
BY 13Z. HAVE SOME LOW POPS WITH THIS AS IT DOES SO. BACK EDGE OF
CLDS WILL SLOWLY PUSH THRU PORTIONS OF SE OH BY 08Z...TAKING TO
NEAR SUNRISE TO GET INTO CENTRAL WV LOWLANDS. FURTHER COMPLICATING
SKY COVER IS LOW STRATUS THAT IS POISED TO DEVELOP ACROSS ALONG
AND E OF I79 CORRIDOR...BASED ON MODEL PROJECTIONS. THINK THIS MAY
END UP MORE IN MTNS AND S COAL FIELDS. SOME RVR VALLEY FG THROWN
IN AS WELL...ESPECIALLY FOR AREAS THAT MANAGE TO CLR.
WILL TRY TO SCT OUT ANY LOW CLDS BY MID MORNING. WILL LOOK FOR MTN
SHRA AND A FEW TSRA TO DEVELOP WITH HEATING AND WEAK OROGRAPHIC
LIFT. WILL CARRY CHC POPS THERE...TAILING OFF TO SCHC BACK TO I79
CORRIDOR. OTHERWISE...WEAK FRONT DROPPING SE THRU UPR OH VALLEY
LOOKS TO BE DELAYED UNTIL LATE AFTN FOR SE OH ZONES BEFORE BECOMING
RATHER DIFFUSE TONIGHT. HAVE ONLY SCHC POPS WITH THIS AS OVERALL
SETUP LOOKS RATHER MEAGER.
WILL ROLL A TICK OR TWO ABV WARMEST GUIDANCE FOR HIGHS TDY BASED
ON RECENT PERFORMANCE AND NEAR HIGH SIDE OF GUIDANCE FOR LOWS
TONIGHT.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
MODELS HAVE COME INTO DECENT AGREEMENT THROUGHOUT THE PERIOD. MODELS
SHOW HIGH PRESSURE FOR FRIDAY. MESO NAM IS TRYING TO CREATE A FEW
SHOWERS IN THE MOUNTAINS...BUT BELIEVE THAT THE 700 MB AIR IS TOO
DRY. A FAST MOVING COLD FRONT THEN PUSHES THROUGH ON SATURDAY. WILL
FINE TUNE POPS FOR BETTER TIMING. HIGH PRESSURE THEN TAKES OVER
SATURDAY NIGHT INTO THE NEXT WORK WEEK. WILL REMOVE POPS SATURDAY
NIGHT THROUGH SUNDAY NIGHT.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
MADE WHOLESALE CHANGES TO THE LONG TERM FORECAST AS MODELS COMING
INTO BETTER AGREEMENT THAN YESTERDAY...NOW SHOWING OPEN WAVE
SWINGING THROUGH OVER THE WEEKEND...AND A THING OF THE PAST AS WE
HEAD INTO THE WORK WEEK. LINGER CHANCE AND SLIGHT CHANCE POPS
THROUGH SUNDAY...MOVING OUT SUNDAY NIGHT AS THE UPPER TROUGH MOVES
EAST AND OUT TO SEA. THIS WILL PROVIDE A MAINLY DRY FORECAST FOR THE
REST OF THE LONG TERM. DID NOT INCLUDE ANY POPS FOR THE WORK WEEK AT
THIS TIME DUE TO LACKING MOISTURE...BUT WITH NORTHWEST FLOW IT MAY
BE POSSIBLE TO GET A LITTLE SHORTWAVE RIPPLE THAT COULD POP A SHOWER
OR TWO AT SOME POINT. TEMPERATURES WILL START OFF BELOW NORMAL ON
MONDAY...WITH A GRADUAL WARMING TREND TO NEAR NORMAL BY MID TO LATE
WEEK AS UPPER RIDGE MOVES INTO SOUTHERN PLAINS.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
YET ANOTHER TRICKY AVIATION FCST THRU THIS MORNING. AN ABUNDANCE
OF MID/HI CLDS WILL BE SLOW TO PUSH E...TAKING UNTIL SUNRISE OR SO
TO EXIT N MTNS COURTESY OF S/W TROF AND EMBEDDED VORT MAX. IN FACT
SOME SHRA NOTED WITH THIS FEATURE AND HAVE SHRA MENTION IN TAFS
NEXT FEW HRS FOR KEKN WITH VCSH AT KHTS.
FURTHER COMPLICATING MATTERS IS ABUNDANCE OF LLVL MOISTURE
REMAINING WHICH MAY LEAD TO LOW STRATUS FORMATION AFTER 09Z. THIS
LOOKS TO BE MOST LKLY ACROSS S COAL FIELDS AND IN THE MTNS WHERE
KBKW WAS CODED UP WITH IFR CIGS THRU 13Z. THINK KEKN MAY FG DOWN
INSTEAD AND HAVE LIFR CONDITIONS AS A RESULT. ELSEWHERE...HARD TO
PIN DOWN FG DEVELOPMENT GIVING MID/HI CLDS CURRENTLY OVER AREA.
WILL ALLOW KPKB AND KCRW TO GO INTO IFR/LIFR 10 TO 12Z WITH MVFR
VSBY FOR KHTS AND KCKB.
ANY FG AND STRATUS WILL MIX OUT 13 TO 14Z FOR A RETURN TO VFR
CONDITIONS. AFTN HEATING WILL ALLOW FOR LOW END CU DEVELOPMENT
WITH SOME MTN CONVECTION POSSIBLE. LEFT OUT OF MTN TAFS AT THIS
DISTANCE THOUGH DUE TO LACK OF EXPECTED COVERAGE. A WEAK COLD FRONT
WILL DROP SE INTO UPR OH VALLEY THIS AFTN...TAKING UNTIL LATE TO
CROSS INTO SE OH. SOME SHRA OR TSRA POSSIBLE WITH THIS BUT CHCS
TOO LOW FOR INCLUDING IN NEAREST TAF SITE...KPKB...BEFORE BOUNDARY
BECOMES RATHER DIFFUSE IN NATURE TONIGHT E OF OH RVR.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY...
FORECAST CONFIDENCE: LOW.
ALTERNATE SCENARIOS: TIMING AND DENSITY OF FOG AND/OR LOW STRATUS
MAY VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE THU 09/06/12
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13
CRW CONSISTENCY M L L L L L L H H H H H
HTS CONSISTENCY M L L L L L L H H H H H
BKW CONSISTENCY H M M M H H H H H H H H
EKN CONSISTENCY M L L L L L L L H H H H
PKB CONSISTENCY M L L L L L L H H H H H
CKB CONSISTENCY M M L L L L L H H H H H
AFTER 06Z FRIDAY...
IFR FOG EXPECTED AT SOME TERMINALS 09 TO 12Z THURSDAY. BRIEF IFR
POSSIBLE IN THUNDERSTORMS SATURDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30
NEAR TERM...30
SHORT TERM...RPY
LONG TERM...MZ
AVIATION...30
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
229 AM EDT THU SEP 6 2012
.SYNOPSIS...
WEAK COLD FRONT ARRIVES THIS EVENING FOLLOWED BY AN UPPER LEVEL
LOW AND SURFACE COLD FRONT FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE...
SHRA CONT TO INCREASE ACROSS N CARTER AND S GREENUP AS OF
0630Z...WITH NEARLY STATIONARY MOTIONS. BUMPED UP POPS INTO LKLY
NEXT COUPLE HRS ACROSS NE KY COUNTIES. WILL BE MONITORING RAINFALL
AS WELL.
PREVIOUS DISCUSSION BELOW...
SHRA LIGHTING UP ON RADAR AT 06Z ACROSS W ZONES...ASSOCIATED WITH
S/W TROF AND EMBEDDED VORT MAX. RUC TRACKS THIS SLOWLY NE THRU CWA
BY 13Z. HAVE SOME LOW POPS WITH THIS AS IT DOES SO. BACK EDGE OF
CLDS WILL SLOWLY PUSH THRU PORTIONS OF SE OH BY 08Z...TAKING TO
NEAR SUNRISE TO GET INTO CENTRAL WV LOWLANDS. FURTHER COMPLICATING
SKY COVER IS LOW STRATUS THAT IS POISED TO DEVELOP ACROSS ALONG
AND E OF I79 CORRIDOR...BASED ON MDL PROJECTIONS. THINK THIS MAY
END UP MORE IN MTNS AND S COAL FIELDS. SOME RVR VALLEY FG THROWN
IN AS WELL...ESPECIALLY FOR AREAS THAT MANAGE TO CLR.
WILL TRY TO SCT OUT ANY LOW CLDS BY MID MORNING. WILL LOOK FOR MTN
SHRA AND A FEW TSRA TO DEVELOP WITH HEATING AND WEAK OROGRAPHIC
LIFT. WILL CARRY CHC POPS THERE...TAILING OFF TO SCHC BACK TO I79
CORRIDOR. OTHERWISE...WEAK FRONT DROPPING SE THRU UPR OH VALLEY
LOOKS TO BE DELAYED UNTIL LATE AFTN FOR SE OH ZONES BEFORE BECOMING
RATHER DIFFUSE TONIGHT. HAVE ONLY SCHC POPS WITH THIS AS OVERALL
SETUP LOOKS RATHER MEAGER.
WILL ROLL A TICK OR TWO ABV WARMEST GUIDANCE FOR HIGHS TDY BASED
ON RECENT PERFORMANCE AND NEAR HIGH SIDE OF GUIDANCE FOR LOWS
TONIGHT.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
PRECIP WILL COME TO AN END FROM WEST TO EAST THURSDAY NIGHT AS WEAK
FRONT PULLS AWAY/DISSIPATES. NAM LINGERS MOISTURE INTO
FRIDAY...WHILE GFS IS A BIT FASTER MOVING IT OUT. HAVE SLIGHT CHANCE
POPS IN THE MOUNTAINS FRIDAY AFTERNOON TO ACCOUNT FOR ANY ISOLATED
DIURNAL CONVECTION THAT MAY DEVELOP.
ONLY A SHORT BREAK BEFORE THE NEXT SYSTEM MOVES IN FOR THE WEEKEND.
MODELS AND ENSEMBLES HAVE CONTINUED TRENDING TOWARDS THE IDEA OF AN
OPEN TROUGH...AND KEEP IT FAIRLY PROGRESSIVE. WITH THIS IN
MIND...SPED UP ENTIRE SYSTEM A BIT...WITH SLIGHT CHANCE POPS
ENTERING SE OHIO LATE FRIDAY EVENING AND INTO THE WV MOUNTAINS
OVERNIGHT. THEN HAVE LIKELY POPS INTO SE OHIO BY SATURDAY MORNING
AND THE WV MOUNTAINS EARLY SATURDAY AFTERNOON. KEPT THE HIGHEST POPS
ALONG AND IN FRONT OF THE SURFACE COLD FRONT...WHICH SHOULD CROSS
THE OHIO RIVER 18Z-20Z AND EXIT EAST OF FORECAST AREA SATURDAY
NIGHT.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
MADE WHOLESALE CHANGES TO THE LONG TERM FORECAST AS MODELS COMING
INTO BETTER AGREEMENT THAN YESTERDAY...NOW SHOWING OPEN WAVE
SWINGING THROUGH OVER THE WEEKEND...AND A THING OF THE PAST AS WE
HEAD INTO THE WORK WEEK. LINGER CHANCE AND SLIGHT CHANCE POPS
THROUGH SUNDAY...MOVING OUT SUNDAY NIGHT AS THE UPPER TROUGH MOVES
EAST AND OUT TO SEA. THIS WILL PROVIDE A MAINLY DRY FORECAST FOR THE
REST OF THE LONG TERM. DID NOT INCLUDE ANY POPS FOR THE WORK WEEK AT
THIS TIME DUE TO LACKING MOISTURE...BUT WITH NORTHWEST FLOW IT MAY
BE POSSIBLE TO GET A LITTLE SHORTWAVE RIPPLE THAT COULD POP A SHOWER
OR TWO AT SOME POINT. TEMPERATURES WILL START OFF BELOW NORMAL ON
MONDAY...WITH A GRADUAL WARMING TREND TO NEAR NORMAL BY MID TO LATE
WEEK AS UPPER RIDGE MOVES INTO SOUTHERN PLAINS.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
YET ANOTHER TRICKY AVIATION FCST THRU THIS MORNING. AN ABUNDANCE
OF MID/HI CLDS WILL BE SLOW TO PUSH E...TAKING UNTIL SUNRISE OR SO
TO EXIT N MTNS COURTESY OF S/W TROF AND EMBEDDED VORT MAX. IN FACT
SOME SHRA NOTED WITH THIS FEATURE AND HAVE SHRA MENTION IN TAFS
NEXT FEW HRS FOR KEKN WITH VCSH AT KHTS.
FURTHER COMPLICATING MATTERS IS ABUNDANCE OF LLVL MOISTURE
REMAINING WHICH MAY LEAD TO LOW STRATUS FORMATION AFTER 09Z. THIS
LOOKS TO BE MOST LKLY ACROSS S COAL FIELDS AND IN THE MTNS WHERE
KBKW WAS CODED UP WITH IFR CIGS THRU 13Z. THINK KEKN MAY FG DOWN
INSTEAD AND HAVE LIFR CONDITIONS AS A RESULT. ELSEWHERE...HARD TO
PIN DOWN FG DEVELOPMENT GIVING MID/HI CLDS CURRENTLY OVER AREA.
WILL ALLOW KPKB AND KCRW TO GO INTO IFR/LIFR 10 TO 12Z WITH MVFR
VSBY FOR KHTS AND KCKB.
ANY FG AND STRATUS WILL MIX OUT 13 TO 14Z FOR A RETURN TO VFR
CONDITIONS. AFTN HEATING WILL ALLOW FOR LOW END CU DEVELOPMENT
WITH SOME MTN CONVECTION POSSIBLE. LEFT OUT OF MTN TAFS AT THIS
DISTANCE THOUGH DUE TO LACK OF EXPECTED COVERAGE. A WEAK COLD FRONT
WILL DROP SE INTO UPR OH VALLEY THIS AFTN...TAKING UNTIL LATE TO
CROSS INTO SE OH. SOME SHRA OR TSRA POSSIBLE WITH THIS BUT CHCS
TOO LOW FOR INCLUDING IN NEAREST TAF SITE...KPKB...BEFORE BOUNDARY
BECOMES RATHER DIFFUSE IN NATURE TONIGHT E OF OH RVR.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY...
FORECAST CONFIDENCE: LOW.
ALTERNATE SCENARIOS: TIMING AND DENSITY OF FOG AND/OR LOW STRATUS
MAY VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE THU 09/06/12
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13
CRW CONSISTENCY M L L L L L L H H H H H
HTS CONSISTENCY M L L L L L L H H H H H
BKW CONSISTENCY H M M M H H H H H H H H
EKN CONSISTENCY M L L L L L L L H H H H
PKB CONSISTENCY M L L L L L L H H H H H
CKB CONSISTENCY M M L L L L L H H H H H
AFTER 06Z FRIDAY...
IFR FOG EXPECTED AT SOME TERMINALS 09 TO 12Z THURSDAY. BRIEF IFR
POSSIBLE IN THUNDERSTORMS SATURDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30
NEAR TERM...30
SHORT TERM...MZ
LONG TERM...MZ
AVIATION...30
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
209 AM EDT THU SEP 6 2012
.SYNOPSIS...
WEAK COLD FRONT ARRIVES THIS EVENING FOLLOWED BY AN UPPER LEVEL
LOW AND SURFACE COLD FRONT FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
SHRA LIGHTING UP ON RADAR AT 06Z ACROSS W ZONES...ASSOCIATED WITH S/W
TROF AND EMBEDDED VORT MAX. RUC TRACKS THIS SLOWLY NE THRU CWA BY
13Z. HAVE SOME LOW POPS WITH THIS AS IT DOES SO. BACK EDGE OF CLDS
WILL SLOWLY PUSH THRU PORTIONS OF SE OH BY 08Z...TAKING TO NEAR
SUNRISE TO GET INTO CENTRAL WV LOWLANDS. FURTHER COMPLICATING SKY
COVER IS LOW STRATUS THAT IS POISED TO DEVELOP ACROSS ALONG AND E
OF I79 CORRIDOR...BASED ON MDL PROJECTIONS. THINK THIS MAY END UP
MORE IN MTNS AND S COAL FIELDS. SOME RVR VALLEY FG THROWN IN AS
WELL...ESPECIALLY FOR AREAS THAT MANAGE TO CLR.
WILL TRY TO SCT OUT ANY LOW CLDS BY MID MORNING. WILL LOOK FOR MTN
SHRA AND A FEW TSRA TO DEVELOP WITH HEATING AND WEAK OROGRAPHIC
LIFT. WILL CARRY CHC POPS THERE...TAILING OFF TO SCHC BACK TO I79
CORRIDOR. OTHERWISE...WEAK FRONT DROPPING SE THRU UPR OH VALLEY
LOOKS TO BE DELAYED UNTIL LATE AFTN FOR SE OH ZONES BEFORE BECOMING
RATHER DIFFUSE TONIGHT. HAVE ONLY SCHC POPS WITH THIS AS OVERALL
SETUP LOOKS RATHER MEAGER.
WILL ROLL A TICK OR TWO ABV WARMEST GUIDANCE FOR HIGHS TDY BASED
ON RECENT PERFORMANCE AND NEAR HIGH SIDE OF GUIDANCE FOR LOWS
TONIGHT.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
PRECIP WILL COME TO AN END FROM WEST TO EAST THURSDAY NIGHT AS WEAK
FRONT PULLS AWAY/DISSIPATES. NAM LINGERS MOISTURE INTO
FRIDAY...WHILE GFS IS A BIT FASTER MOVING IT OUT. HAVE SLIGHT CHANCE
POPS IN THE MOUNTAINS FRIDAY AFTERNOON TO ACCOUNT FOR ANY ISOLATED
DIURNAL CONVECTION THAT MAY DEVELOP.
ONLY A SHORT BREAK BEFORE THE NEXT SYSTEM MOVES IN FOR THE WEEKEND.
MODELS AND ENSEMBLES HAVE CONTINUED TRENDING TOWARDS THE IDEA OF AN
OPEN TROUGH...AND KEEP IT FAIRLY PROGRESSIVE. WITH THIS IN
MIND...SPED UP ENTIRE SYSTEM A BIT...WITH SLIGHT CHANCE POPS
ENTERING SE OHIO LATE FRIDAY EVENING AND INTO THE WV MOUNTAINS
OVERNIGHT. THEN HAVE LIKELY POPS INTO SE OHIO BY SATURDAY MORNING
AND THE WV MOUNTAINS EARLY SATURDAY AFTERNOON. KEPT THE HIGHEST POPS
ALONG AND IN FRONT OF THE SURFACE COLD FRONT...WHICH SHOULD CROSS
THE OHIO RIVER 18Z-20Z AND EXIT EAST OF FORECAST AREA SATURDAY
NIGHT.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
MADE WHOLESALE CHANGES TO THE LONG TERM FORECAST AS MODELS COMING
INTO BETTER AGREEMENT THAN YESTERDAY...NOW SHOWING OPEN WAVE
SWINGING THROUGH OVER THE WEEKEND...AND A THING OF THE PAST AS WE
HEAD INTO THE WORK WEEK. LINGER CHANCE AND SLIGHT CHANCE POPS
THROUGH SUNDAY...MOVING OUT SUNDAY NIGHT AS THE UPPER TROUGH MOVES
EAST AND OUT TO SEA. THIS WILL PROVIDE A MAINLY DRY FORECAST FOR THE
REST OF THE LONG TERM. DID NOT INCLUDE ANY POPS FOR THE WORK WEEK AT
THIS TIME DUE TO LACKING MOISTURE...BUT WITH NORTHWEST FLOW IT MAY
BE POSSIBLE TO GET A LITTLE SHORTWAVE RIPPLE THAT COULD POP A SHOWER
OR TWO AT SOME POINT. TEMPERATURES WILL START OFF BELOW NORMAL ON
MONDAY...WITH A GRADUAL WARMING TREND TO NEAR NORMAL BY MID TO LATE
WEEK AS UPPER RIDGE MOVES INTO SOUTHERN PLAINS.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
YET ANOTHER TRICKY AVIATION FCST THRU THIS MORNING. AN ABUNDANCE
OF MID/HI CLDS WILL BE SLOW TO PUSH E...TAKING UNTIL SUNRISE OR SO
TO EXIT N MTNS COURTESY OF S/W TROF AND EMBEDDED VORT MAX. IN FACT
SOME SHRA NOTED WITH THIS FEATURE AND HAVE SHRA MENTION IN TAFS
NEXT FEW HRS FOR KEKN WITH VCSH AT KHTS.
FURTHER COMPLICATING MATTERS IS ABUNDANCE OF LLVL MOISTURE
REMAINING WHICH MAY LEAD TO LOW STRATUS FORMATION AFTER 09Z. THIS
LOOKS TO BE MOST LKLY ACROSS S COAL FIELDS AND IN THE MTNS WHERE
KBKW WAS CODED UP WITH IFR CIGS THRU 13Z. THINK KEKN MAY FG DOWN
INSTEAD AND HAVE LIFR CONDITIONS AS A RESULT. ELSEWHERE...HARD TO
PIN DOWN FG DEVELOPMENT GIVING MID/HI CLDS CURRENTLY OVER AREA.
WILL ALLOW KPKB AND KCRW TO GO INTO IFR/LIFR 10 TO 12Z WITH MVFR
VSBY FOR KHTS AND KCKB.
ANY FG AND STRATUS WILL MIX OUT 13 TO 14Z FOR A RETURN TO VFR
CONDITIONS. AFTN HEATING WILL ALLOW FOR LOW END CU DEVELOPMENT
WITH SOME MTN CONVECTION POSSIBLE. LEFT OUT OF MTN TAFS AT THIS
DISTANCE THOUGH DUE TO LACK OF EXPECTED COVERAGE. A WEAK COLD FRONT
WILL DROP SE INTO UPR OH VALLEY THIS AFTN...TAKING UNTIL LATE TO
CROSS INTO SE OH. SOME SHRA OR TSRA POSSIBLE WITH THIS BUT CHCS
TOO LOW FOR INCLUDING IN NEAREST TAF SITE...KPKB...BEFORE BOUNDARY
BECOMES RATHER DIFFUSE IN NATURE TONIGHT E OF OH RVR.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY...
FORECAST CONFIDENCE: LOW.
ALTERNATE SCENARIOS: TIMING AND DENSITY OF FOG AND/OR LOW STRATUS
MAY VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE THU 09/06/12
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13
CRW CONSISTENCY M L L L L L L H H H H H
HTS CONSISTENCY M L L L L L L H H H H H
BKW CONSISTENCY H M M M H H H H H H H H
EKN CONSISTENCY M L L L L L L L H H H H
PKB CONSISTENCY M L L L L L L H H H H H
CKB CONSISTENCY M M L L L L L H H H H H
AFTER 06Z FRIDAY...
IFR FOG EXPECTED AT SOME TERMINALS 09 TO 12Z THURSDAY. BRIEF IFR
POSSIBLE IN THUNDERSTORMS SATURDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30
NEAR TERM...30
SHORT TERM...MZ
LONG TERM...MZ
AVIATION...30
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
515 AM EDT THU SEP 6 2012
.SYNOPSIS...
A WEAK AREA OF HIGH PRESSURE OVER THE REGION THIS MORNING WILL SLIDE
EAST TO THE SOUTHERN NEW ENGLAND COAST THIS AFTERNOON. A COLD FRONT
WILL MOVE INTO THE AREA TONIGHT AND FRIDAY. AN UPPER TROUGH WILL
FORM OVER THE GREAT LAKES AND MIDWEST DURING THE WEEKEND THEN
AMPLIFY AS IT APPROACHES PENNSYLVANIA...CREATING AN UNSETTLED AND
WET WEATHER PATTERN INTO THE WEEKEND. HIGH PRESSURE WILL BUILD INTO
THE AREA LATE MONDAY...BRINGING IN COOLER TEMPERATURES...BEFORE
MOVING OFF THE COAST LATER IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A WEAK RIDGE OF HIGH PRESSURE /1012MB/ RESIDES OVER THE REGION EARLY
THIS MORNING. MODERATELY STG...MID/UPPER WARM ADVECTION WAS
RESPONSIBLE CREATING AN EXTENSIVE /AND THICK/ SHIELD OF ALTO CU AND
CIRROSTRATUS OVER THE STATE.
THE WESTERN EDGE OF THIS MID AND HIGH CLOUD SHIELD /NEAR THE
OHIO/PENN BORDER AT 09Z/ WILL CONTINUE TO SLIDE TO THE EAST AT
APPROX 20KT...AND REACH A LINE FROM KELM...TO KUNV AND KAOO BY
15-16Z TDY...AND 17-19Z ACROSS THE WEST BRANCH AND MID SUSQ VALLEY.
MIN TEMPS AROUND SUNRISE WILL HAVE QUITE A TIGHT RANGE OF ONLY ABOUT
6-7 DEG F /U50S TO MID 60S/ FROM THE NORMALLY COLDER NW MTNS...TO
THE LOWER SUSQ VALLEY.
THE UPPER SHORTWAVE WITH IT/S PRECEDING WARM ADVECTION ALOFT AND
ITS BKN MID AND HIGH CLOUD DECK WILL BE PASSING EAST OF THE AREA
DURING THE LATE MORNING AND EARLY AFTERNOON HOURS. BEHIND THIS
FEATURE...06Z RUC SUPPORTS A MSUNNY MORNING ACROSS THE WESTERN
MTNS...WITH INCREASING/LESS FILTERED SUNSHINE FOR THE AFTERNOON
ACROSS THE SE HALF OF THE CWA.
THE SUNSHINE AND MDL 8H TEMPS ARND 17C WILL ALLOW TEMPS TO CLIMB
QUICKLY INTO THE 80S BY AFTN...WITH THE LOWER SUSQ VALLEY NEARING
90F.
AFTER AN APPROX 7-8 HOUR PERIOD OF TRANQUIL CONDITIONS FOR THE FIRST
HALF OF THE DAYLIGHT HOURS...CU WILL INCREASE AND GROW VERTICALLY
DURING THE AFTN...AS A POCKET OF STEEP MID LEVEL LAPSE RATES /AROUND
7C PER KM/ OVERSPREADS THE CWA AHEAD OF NEXT SHORTWAVE AND ASSOC
COLD FRONT.
00Z-03Z MDLS/SREF GENERATE A RESPECTABLE AMOUNT OF CAPE BY LATE IN
THE AFTERNOON TODAY. THE BEST CHC OF TSRA WILL BE ACROSS THE NCENT
AND NW MTNS...WHERE LARGE SCALE FORCING AND DECENT UPPER LEVEL
DIVERGENCE...WILL COMBINE WITH MDTLY STG LLVL THETA-E CONVERGENCE
AND MID-LEVEL WESTERLY WINDS.
SFC DEW POINTS MAINLY IN THE LOWER TO MID 60S...WILL HELP TO CREATE
MLCAPES AROUND 1500 J/KG THIS AFTERNOON INTO EARLY THIS EVENING.
THIS INSTABILITY COMBINED WITH THE MODERATE WIND SHEAR COULD BE
ENOUGH TO SUPPORT ISOLD SVR MULTI-CELL TSTORMS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
WEAK LLVL RIDGING MOVES IN FROM THE WEST AS THE BEST UPPER LEVEL
DIVERGENCE WANES/SHIFTS TWD THE MID ATLANTIC COAST. SCATTERED
SHRA/TSRA WILL OCCUR MAINLY BEFORE MIDNIGHT...BUT ISOLATED SHRA/TSRA
WILL STILL BE POSSIBLE LATE AS THE LLVL FRONTAL BOUNDARY STALLS OUT
TEMPORARILY FROM ABOUT KAVP TO KUNV AND KPIT...AND MU/ML CAPES
REMAIN QUITE HIGH GIVEN THE LINGERING POCKET OF STEEP LAPSE RATES
ALOFT AND MOIST BLYR WITH DEWPOINTS IN THE LOWER TO MID 60S ACROSS
THE CENTRAL ZONES...AND PERHAPS AROUND A MUGGY 70F IN THE
SOUTHEAST.
WEAK HIGH BUILDS INTO THE AREA BY LATE FRIDAY AS THE FRONTAL
BOUNDARY LIFTS NORTH AS A WARM FRONT INTO NEW YORK STATE. SW FLOW AT
THE SFC AND ALOFT WILL MAINTAIN VERY WARM AND SOMEWHAT HUMID
CONDITIONS...ESP IN THE SOUTH WHERE TEMPS WILL TOP OUT IN THE U80S
TO LOWER 90S WITH SFC DEWPOINTS IN THE U60S TO AROUND 70F.
HIGH TEMPS IN ALL AREAS FRIDAY WILL ONCE AGAIN BE 10-12F ABOVE
NORMAL.
GRIDDED SKY COVER /CU TOPPED BY PERIODS OF CIRRUS/ WILL AVERAGE
AROUND 50 PERCENT THROUGH THE DAY FRIDAY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
CLOUDS THICKEN UP WITH SHRA/TSRA BECOMING LIKELY WELL AFTER MIDNIGHT
ACROSS THE ALLEGHENY PLATEAU OF NRN AND WRN PENN.
LOW LEVEL WIND SHEAR COULD IMPACT AVIATION AND BE FELT ACRS THE
HIGHER TERRAIN FRIDAY NIGHT INTO SATURDAY...AS THE SSW FLOW IN THE
1-2 KFT AGL LAYER STRENGTHENS TO 35-40 KTS.
DEEP LOW FCST TO DRAG A WARM FRONT...THEN A COLD FRONT ACROSS THE
AREA ON SAT. MODELS DO NOT CLOSE LOW OFF NOW...BUT STILL LOOKS WET.
SOME CHC OF STRONG TO PERHAPS SEVERE STORMS ACROSS THE EAST LATE.
LESS CHC FOR WIDESPREAD HEAVY RAIN NOW...AS SYSTEM DOES NOT CLOSE
OFF AND GO NEGATIVE. STILL WILL BE WET FOR MUCH OF THE DAY.
RATHER STRONG UPPER LVL LOW MOVING ACROSS THE REGION ON SUNDAY...
THUS EXPECT CU TO DEVELOP FAST...LIMIT MAX TEMPS...AND RESULT IN
SHOWERS AND STORMS. DID LOWER TEMPS A TAD FOR SOME PERIODS AFTER
SATURDAY.
WITH THE UPPER LVL LOW MOVING OUT FASTER NOW...SHOULD BE DRY ON
MONDAY.
TUE AND WED LOOK DRY WITH HIGH PRESSURE OVER WV.
&&
.AVIATION /09Z THURSDAY THROUGH MONDAY/...
CURRENT SATELLITE HAS WIDESPREAD MIDDLE TO HIGH CLOUDS MOVING OVER
THE STATE. THIS WILL REDUCE THE PROBABILITIES FOR FOG OVERNIGHT AND
THIS MORNING. CURRENT DEW POINT DEPRESSIONS ARE IN THE SINGLE
DIGITS...WHICH IS A GOOD SIDE FOR FOG. WITH THE CALM WINDS ACROSS
THE BOARD AND AN INVERSION IN PLACE...PATCHY FOG IS CERTAINLY
PROBABLY THROUGH ANY MID TO HIGH CLOUDS WILL REDUCE ITS INTENSITY.
SO EXPECT TO SEE THE DEVELOPMENT OF SOME VALLEY FOG BY 2-4 AM AND
CONTINUE A FEW HOURS AFTER SUNRISE. VIZ WILL BE THE PRIMARY
RESTRICTIONS UNTIL CONDITIONS LIFT...IN THE 1-3 MILE
RANGE...THOUGH UNV COULD SEE IFR OR LOWER CIGS. CONDITIONS WILL
CONTINUE UNTIL MID TO LATE MORNING.
THURS AFTERNOON WILL SEE SCATTERED CONVECTION BECOMING THE THREAT
WITH LOCALIZED RESTRICTIONS IN THE SHOWERS/STORMS AS WELL AS THE
POTENTIAL FOR ISOLATED STRONG WIND GUSTS IN STRONGER
THUNDERSTORMS.
OUTLOOK...
THU...MAINLY VFR AFTER MORNING FOG. SCT SHOWERS/THUNDERSTORMS
DEVELOPING BY AFTERNOON AND LASTING INTO EVENING.
FRI...MAINLY VFR.
SAT...DETERIORATING CONDITIONS WITH THE APPROACH OF A WAVE OF LOW
PRESSURE.
SUN...MVFR EARLY...IMPROVING DURING THE DAY.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...LAMBERT
LONG TERM...LAMBERT/MARTIN
AVIATION...CERU/GARTNER
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1145 PM CDT WED SEP 5 2012
.SHORT TERM...TONIGHT THROUGH SATURDAY
329 PM CDT WED SEP 5 2012
FOCUS THIS FORECAST PERIOD WAS ON THE NEXT WEATHER SYSTEM COMING
INTO THE AREA THURSDAY NIGHT AND FRIDAY. CHANCES ARE INCREASING
FOR A SHOWER PRODUCER.
CURRENT FRONTAL POSITION TOUGH TO DISCERN RIGHT NOW...BUT MAYBE
THE MORE IMPORTANT ELEMENT IS WHERE THE CONVERGENCE AND
INSTABILITY IS. SURFACE MOISTURE CONVERGENCE CURRENTLY LIES ACROSS
THE SOUTHERNMOST FORECAST AREA PER SPC 19Z ANALYSIS. MLCAPE IS UP
TO 1500 J/KG THERE WITH CIN ABOUT 50 J/KG. THERE IS SOME WEAKER
CONVERGENCE ACROSS NERN IA ALONG ANOTHER WEAK WIND SHIFT FROM WEST
TO N-NW.
THE NEXT FEW HOURS HOLD A CHANCE FOR ISOLATED TSRA ACROSS NERN IA
AND SWRN WI BUT THIS CHANCE SHOULD SHIFT SOUTHEAST BY EVENING.
CURRENTLY DO NOT HAVE A TSRA CHANCE IN THE FORECAST THIS AFTERNOON
OR EVENING.
12Z 250 MB RAOB INFORMATION SHOWING A NICE HEIGHT FALL/RISE/FALL
SIGNAL OVERHEAD AND UPSTREAM INTO WRN ALBERTA...WITH THE
WESTERNMOST FALL OF OVER 100M/12HR ASSOCIATED WITH THE FRIDAY
SHORTWAVE TROUGH SHIFTING SOUTHEAST. A NICE WARM POOL OF AIR SEEN
WITH THAT SHORTWAVE TROUGH OVER ALBERTA/BRITISH COLUMBIA THERE
TOO..AND 100KT JET CORE...WITH LATEST RUC ANALYSIS SHOWING THE
TROPOPAUSE FOLD DOWN TO 500MB OVER CENTRAL BC. SHORTWAVE RIDGE TO
BUILD IN FOR TONIGHT/THURSDAY IS CENTERED NEAR KGGW WITH 80M/12HR
HEIGHT RISES AT 250 MB.
RIDGE BUILDING WILL CONTINUE OVERNIGHT WITH ENOUGH 0-2KM AGL FLOW
/GREATER THAN 10KTS/ TO KEEP MISSISSIPPI RIVER VALLEY FOG OUT OF
THE PICTURE. HOWEVER...HAVE KEPT THE WI RIVER VALLEY FOG IN FOR
THU MORNING AS MORE ORTHOGONAL NW FLOW WILL ALLOW FOR DECOUPLING
IN THE BOUNDARY LAYER. PLUS...DEWPOINTS WILL BE HIGHEST IN THAT
AREA OVERNIGHT...HAVE SLOWED THE DRIER AIR ADVECTION.
ALBERTA/BC SHORTWAVE TROUGH TO BRING FALL-LIKE DYNAMICS TO THE AREA
THURSDAY NIGHT AND INTO FRIDAY. PRETTY GOOD CONSISTENCY IN THE
LARGER SCALE FORCING PRESENTED IN THE 05.12Z NAM/GFS THIS MORNING
AND BECAUSE OF THIS...HAVE RAISED RAIN CHANCES LATE THURSDAY NIGHT
INTO FRIDAY. THE SHORTWAVE ROUGH ENERGY SPLITS AS IT HEADS
SOUTHEAST WITH A PORTION MOVING IN FROM THE DAKOTAS AND THE SECOND
COMING IN FROM THE SOUTHWEST. THESE EACH HAVE A SMALL JET CORE
ASSOCIATED WITH THEM AND BY LATER THU NIGHT-FRIDAY...IT APPEARS THEY
INTERACT IN A COUPLED JET SCENARIO OVER THE AREA FOR GOOD DIVERGENCE
ALOFT. A STRONG BAROCLINIC ZONE IN THE 700-850MB LAYER WITH THE
INITIAL SHORTWAVE TROUGH WILL ALSO CREATE A W-E RAIN BAND WITH ITS
FORCING IN FRONTOGENESIS FROM CENTRAL MN-NRN WI...WHICH SLOWLY
SHIFTS INTO THE NWRN FORECAST AREA BY FRIDAY MORNING. THIS IS
SOMEWHAT IN CONCERT WITH 500-300MB QVECTOR CONVERGENCE.
MEANWHILE...BACK AT THE RANCH...THETA-E CONVERGENCE IN THE LOW-
LEVELS WILL ALSO START INCREASING IN THE WRN AND NRN FORECAST BY
12Z FRIDAY. THEN...QG FORCING INCREASES AS SECOND SHORTWAVE TROUGH
ENERGY PIECE SHIFTS ACROSS THE SOUTHERN FORECAST AREA. 05.12Z
ECMWF HAS THESE COMPONENTS...JUST FURTHER NORTH AND
SOUTH...SPLITTING AROUND THE FORECAST AREA.
05.09Z SREF DATA SUGGESTS ANY CAPE OVER 500 J/KG SHOULD REMAIN SOUTH
OF THE FORECAST AREA WITH DEWPOINTS STRUGGLING TO REACH MIDDLE 50S.
HOWEVER...WITH STEEPER LAPSE RATES IN THE MID-LEVELS AND STRONGER
FRONTOGENESIS...COULD SEE SOME THUNDER THU NIGHT UNTIL IT IS USED
UP.
OVERALL...THE SIGNALS ARE BEST IN THE NRN AND SRN FORECAST
AREA...BUT LARGE ENOUGH SIGNALS EXIST TO MOVE TOWARD A LIGHT RAIN
SHOWER SOLUTION FOR LATE THURSDAY NIGHT AND INTO FRIDAY. AMOUNTS MAY
NOT BE LARGE WITH LIMITED INSTABILITY IN THE FORECAST AREA...AROUND A
QUARTER OF AN INCH TOTAL. RAIN SHOULD CLEAR QUICKLY EAST LATER ON
FRIDAY. CURRENTLY THE FORECAST TEMPERATURES HAVE A 10F DIURNAL RANGE
FRIDAY...AND IF IT SHOWERS ALL DAY...IT WOULD LIKELY BE ABOUT 5F.
CONFIDENCE IS INCREASING ON THE RAIN EVENT...BUT NOT HIGH ENOUGH TO
CUT HIGHS FRIDAY MORE. THIS WILL BE NEEDED IF WE INCREASE THE RAIN
CHANCES MORE IN COMING FORECASTS.
NOTE...THE NCEP GFS MODEL WAS CHANGED TODAY AT 12Z TO TRY AND
SOLVE THE COLD/MOIST BIAS IN THE LOWEST 3KM AGL THAT HAS BEEN
EVIDENT SINCE LAST YEAR. IT APPEARED BETTER WITH ITS
INITIALIZATION IN THE LOW LEVELS.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
329 PM CDT WED SEP 5 2012
WITH NORTHWEST FLOW OVER THE AREA FOR THE WEEKEND...THERE IS SOME
SIGNAL FOR A SHORTWAVE TROUGH TO SHIFT THROUGH THE GREAT LAKES
SATURDAY NIGHT. AT THIS TIME THE 05.00Z ECMWF AND 05.12
GEM/GFS/ECMWF REMAIN CONSISTENT IN SHOWERS OVERNIGHT IN EASTERN
WISCONSIN. THERE IS A VERY DEEP TROPOSPHERIC QG FORCING SIGNAL
MOVING THROUGH EASTERN WI PER THE 05.12Z ECMWF. THUS...HAVE ADDED
SOME SMALL SHOWER CHANCES TO CENTRAL WI AREAS. IF THIS SIGNAL
CONTINUES...MORE CLOUD AND HIGHER RAIN CHANCES WILL BE NEEDED. IT
LOOKS LIKE A FAST MOVER TO LIMIT THE IMPACT ON THE WEEKEND
WEATHER.
RIDGE BUILDING THEN IN CONTROL OF WEATHER SUN-TUE WITH
TEMPERATURES WARMING. THERE ARE SOME SIGNALS THAT TUESDAY COULD BE
IN A PREFRONTAL SOUTHWESTERLY FLOW WITH 90F POSSIBLE. HAVE BUMPED
HIGHS ABOUT 3F AND THE ONLY THING HOLDING OFF THE FORECAST OF
WARMER HIGHS IS THE TIMING OF A STRONG FRONT AT DAY 6 CAN GET
TRICKY.
&&
.AVIATION...
1145 PM CDT WED SEP 5 2012
KLSE VALLEY FOG BECOMING MORE OF A CONCERN AS TDS HAVE RISEN IN THE
EVENING...AS EXPECTED...BUT HAVEN/T FALLEN OFF AS MUCH TO THE WEST.
SOME SIGNS THAT IT IS STARTING...AND THIS COULD GRADUALLY WORK INTO
KLSE DURING THE OVERNIGHT HOURS. THE T/TD SPREAD OF 4 F AT 03Z IS
FAVORABLE FOR DENSE FOG AT KLSE. ADD IN SKC...VRB/CALM WINDS...AND
MOIST GROUNDS FROM RECENT RAINS AND IT IS NEARLY AN IDEAL SETUP.
HOWEVER...THE DEPTH OF THE LIGHT WINDS IS NOT OVERLY DEEP...PER
BUFKIT SOUNDINGS. MORE IMPORTANTLY...AND PROBABLY WHAT WILL BE MAIN
FACTOR OF WHETHER OR NOT 1/4SM FG WILL FORM AT KLSE...IS HOW SOON
THAT DRY AIR WORKS IN. IF IT HANGS JUST WEST...DENSE FOG IS
PROBABLE. IF IT STARTS TO MOVE IN BY 09Z...P6SM SHOULD BE PREVALENT.
WILL HOLD WITH THE BCFG FOR NOW AS OBS ARE INDICATING THAT DRYING IS
STARTING TO PRESS IN.
THE HIGH WILL EXIT EAST THU NIGHT...ALLOWING FOR A COUPLE UPPER
LEVEL SHORTWAVE TROUGHS TO TAKE AIM ON THE UPPER MISSISSIPPI RIVER
VALLEY. FORCING/LIFT AND INCREASING SATURATION WILL RESULT IN CLOUDS
AND A CHANCE FOR SHRA. THE BETTER RAIN CHANCES SHOULD LIE
NORTH-SOUTH OF KRST/KLSE...WHERE THE SHORTWAVES ARE EXPECTED TO
TRAVERSE. BUT ENOUGH LIFT/MOISTURE FOR SOME SCT SHRA LATE THU NIGHT.
LITTLE IF ANY INSTABILITY...SO DON/T EXPECT A TS THREAT AT THIS
TIME.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
329 PM CDT WED SEP 5 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM....BAUMGARDT
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS ALBANY NY
927 AM EDT THU SEP 6 2012
.SYNOPSIS...
DRY WEATHER IS EXPECTED TO CONTINUE THROUGH AT LEAST THE FIRST HALF
OF THE DAY...AS A WEAK RIDGE OF HIGH PRESSURE DRIFTS EASTWARD ACROSS
THE REGION. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL
DEVELOP THIS AFTERNOON AND MAY PERSIST INTO TONIGHT AS ANOTHER WEAK
FRONTAL BOUNDARY CROSSES THE AREA. THE FRONT WILL THEN STALL SOUTH
AND EAST OF THE REGION FRIDAY...BEFORE A STRONGER FRONT APPROACHES
FROM THE WEST LATE SATURDAY BRINGING THE POTENTIAL FOR RAIN.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 915 AM...AREAS OF DENSE FOG CONTINUE TO LIFT WITH RAPID
IMPROVEMENTS IN THE VISIBILITY UNDERWAY. THEREFORE...WE HAVE
REMOVED MENTION OF FOG FROM THE GRIDS/FORECAST. 1KM VISIBLE
IMAGERY THIS MORNING SUGGESTS AMPLE BREAKS IN THE CLOUDS ACROSS
THE DACKS...WESTERN MOHAWK VALLEY AND INTO CENTRAL NY. WITHIN THIS
REGION OF INSOLATION...TEMPERATURES ARE RESPONDING WITH LOWER 70S
QUITE COMMON AND THIS TREND OF PARTIAL SUNSHINE AND WARMING TEMPS
WILL SPREAD EAST THROUGH THIS MORNING. THEN OUR ATTENTION BECOMES
A FOCUS FOR CONVECTION THIS AFTERNOON. THIS MORNINGS 12Z SOUNDINGS
REVEALS RATHER STEEP MID LEVEL LAPSE RATES AHEAD OF WEAKENING COLD
FRONT CROSSING SOUTHWEST ONTARIO AND INTO WESTERN LAKE ERIE. H2O
VAPOR IMAGERY DOES SUGGEST THE MAIN MID LEVEL IMPULSE WAS JUST
EAST OF THE HUDSON RIVER VALLEY. SO THERE WILL BE A DISCONNECT
BETWEEN THE SURFACE FRONT AND UPPER LEVEL IMPULSE.
HOWEVER...LATEST FORECAST HRRR AND SPC WRF REFLECTIVITYS SUGGEST
A SCT-BKN LINE OF CONVECTION TO DEVELOP ALONG EITHER THE FRONTAL
BOUNDARY AND/OR LAKE BREEZE TRACKING EASTWARD THROUGH THE
AFTERNOON. FORECAST SBCAPES ARE AT OR GREAT THAN 1000 J/KG WITH
FORECAST MID LEVEL LAPSE RATES IN THE 6.5 C/KM RANGE. SO THERE IS
A POTENTIAL FOR A COUPLE OF THESE CELLS TO BECOME A LITTLE MORE
ROBUST BUT SEVERE WEATHER THRESHOLDS ARE EXPECTED TO REMAIN JUST
BELOW. PER SPC SWODY1...WE WILL REMAIN WITHIN THE 5% CONTOUR WHICH
MAINLY ENCOMPASSES UPSTATE NY.
LATEST LAV/LAMP AND THOSE 12Z SOUNDINGS SUGGEST A SLIGHT DOWNWARD
MODIFICATION TO FORECAST HIGH TEMPERATURES. DEWPOINTS ALSO REQUIRE
SLIGHT MODIFICATIONS THIS MORNING WITH SLIGHTLY LOWER
VALUES...THEN A RECOVERY EXPECTED WITH SOME MOISTURE POOLING ALONG
AND AHEAD OF THE APPROACHING FRONT.
OVERALL...TEMPS TODAY ARE EXPECTED TO TOP OUT CLOSE TO 10 DEGREES
ABOVE NORMAL FOR THIS TIME OF YEAR.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
CHANCES FOR CONVECTION SHOULD DECREASE AFTER DARK DUE TO LOSS OF
DAYTIME HEATING AND LACK OF SIGNIFICANT FORCING. THE AFOREMENTIONED
WEAK FRONT WILL STALL SOMEWHERE NEAR THE SOUTHERN PORTION OF THE
FORECAST AREA AND BECOME SOMEWHAT DIFFUSE OVERNIGHT. WE SHOULD GET A
QUIET PERIOD FROM OVERNIGHT INTO EARLY FRIDAY MORNING. ON
FRIDAY...THE FRONT WILL STILL BE IN THE VICINITY OF SOUTHERN AREAS
AND COULD PROVIDE A TRIGGER FOR A FEW SHOWERS AND
THUNDERSTORMS...ESPECIALLY DURING THE AFTERNOON. FORCING AGAIN VERY
WEAK...SO CANNOT JUSTIFY GOING WITH MORE THAN ISOLATED POPS.
INSTABILITY COULD BE SUFFICIENT FOR A FEW STRONGER STORMS...BUT FEEL
THE NAM IS OVERDONE WITH CAPE MAGNITUDE AS SURFACE DEWPOINTS SHOULD
BE LOWER ON FRIDAY THAN THURSDAY.
FRIDAY NIGHT SOUTHERLY FLOW WILL START TO INCREASE...AS A POTENT
UPPER LEVEL TROUGH DIGS FROM SOUTHERN CANADA INTO THE GREAT
LAKES...SPAWNING A POTENTIAL WAVE OR MULTIPLE WAVES OF LOW PRESSURE
ALONG THE ASSOCIATED COLD FRONT AT THE SURFACE IN THE LOWER GREAT
LAKES/OHIO REGION. THE JET ENERGY AND DYNAMICS WITH THIS TROUGH ARE
STRONGER THAN WE HAVE SEEN FROM A SYSTEM IN QUITE SOME TIME. AS THE
UPPER LEVEL PATTEN AMPLIFIES FRIDAY NIGHT...SOUTHERLY FLOW ALOFT
WILL INCREASE TO AROUND 35-50 KT AT 850MB. SOME UPSLOPE SHOWERS MAY
DEVELOP BY EARLY SATURDAY MORNING OVER FAVORED SOUTHERN/WESTERN
ADIRONDACKS. IT WILL BE A MILD NIGHT...WITH A PERSISTENT SOUTHERLY
BREEZE ACROSS THE HIGHER TERRAIN AND IN FAVORED NORTH-SOUTH ORIENTED
VALLEYS.
SHOWERS WILL INCREASE IN COVERAGE SATURDAY MORNING MAINLY ACROSS
WESTERN PORTIONS OF THE AREA...BUT WILL INITIALLY HAVE A DIFFICULT
TIME TRANSLATING EASTWARD AS THE UPPER FLOW PATTERN CONTINUES TO
AMPLIFY. THE SPEED OF PROGRESSION OF THE SURFACE COLD FRONT AND
ASSOCIATED RAIN INTO THE REGION IS STILL SOMEWHAT IN QUESTION DUE TO
POTENTIAL SURFACE WAVE DEVELOPMENT ALONG THE FRONT THAT MAY DELAY
TIMING. MOST SOURCES OF GUIDANCE INDICATING THE UPPER JET ENERGY
WILL LIFT NORTHWARD INTO ONTARIO/QUEBEC AND THUS WOULD ALLOW FOR A
FAIRLY QUICK PROPAGATION OF THE COLD FRONT THROUGH OUR AREA
SATURDAY AFTERNOON AND NIGHT.
SO IT SEEMS LIKE OUR ENTIRE AREA COULD ACTUALLY RECEIVE A GOOD
SOAKING RAINFALL SATURDAY AFTERNOON/EVENING. THERE IS A LOW
PROBABILITY OF SOME THUNDERSTORMS PRODUCING STRONG WINDS...AS MODELS
SHOWING SURFACE BASED CAPE DEVELOPING AHEAD OF THE FRONT ALTHOUGH
THIS IS A CONDITIONAL THREAT THAT DEPENDS ON DEGREE OF HEATING THAT
OCCURS AHEAD OF THE FRONT. WITH THE WIND FIELD ALOFT AND LOW AND
DEEP LAYER WIND SHEAR BEING SO STRONG...IF CONVECTION DEVELOPS SOME
LINEAR SEGMENTS OR BOWS MAY FORM AND PRODUCE DAMAGING WINDS. AGAIN
THIS SCENARIO IS MUDDLED RIGHT NOW BUT BEARS WATCHING.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
A STRONG UPPER LEVEL TROUGH AND ASSOCIATED LOW PRESSURE SYSTEM WILL
MOVE ACROSS THE REGION SATURDAY NIGHT. THE MODEL GUIDANCE DIFFERS
ON THE AMPLITUDE OF THE UPPER TROUGH AND THE TIMING OF THE COLD
FRONT THROUGH THE REGION. AS MENTIONED IN THE SHORT TERM DISCUSSION
THERE IS THE POTENTIAL FOR THE DEVELOPMENT OF A SURFACE WAVE ALONG
THE FRONT WHICH WOULD SLOW THE FRONTS PROGRESS. HAVE CONTINUED THE
LIKELY POPS FROM SATURDAY AFTERNOON THROUGH MUCH OF SATURDAY NIGHT.
ALSO HAVE KEEP CHANCE POPS IN FOR SUNDAY AS THE UPPER TROUGH SWINGS
THROUGH. THERE IS MODEL AGREEMENT THAT RIDGING WILL BUILD IN BEHIND
THIS SYSTEM AT THE SURFACE AND ALOFT BRINGING FAIR AND COOL...AUTUMN
WEATHER TO THE REGION THROUGH MID WEEK.
&&
.AVIATION /13Z THURSDAY THROUGH MONDAY/...
HAVE LIFR CONDITIONS AT TAF SITES DUE TO RADIATIONAL FOG. AN
IMPROVEMENT TO VFR IS EXPECTED BY MID MORNING WITH VFR CONDITIONS
CONTINUING INTO THE EVENING. THERE IS A SLIGHT CHANCE FOR CONVECTION
THIS AFTERNOON AS A WEAK FRONTAL BOUNDARY CROSSES THE
REGION...HOWEVER THE THREAT IS TOO LOW TO INCLUDE IN THE TAFS.
RADIATIONAL FOG IS EXPECTED TO DEVELOP AGAIN TONIGHT RESULTING IN
MVFR AND IFR CONDITIONS.
LIGHT SOUTH-SOUTHWEST WINDS WILL DEVELOP THIS MORNING WITH WINDS
DIMINISHING THURSDAY EVENING.
OUTLOOK...
FRI...MAINLY VFR. MVFR/IFR POSSIBLE DUE TO FOG/BR ESPECIALLY AT
KGFL AND KPSF AT NIGHT/EARLY IN THE MORNING.
SAT...RAIN BECOMING LIKELY WITH A SLIGHT CHC TSTMS.
SUN...VFR/MVFR. CHC -SHRA. MON...VFR. NO SIG WX.
&&
.FIRE WEATHER...
NO FIRE WEATHER RELATED ISSUED ARE EXPECTED THROUGH THE PERIOD. DRY
WEATHER IS EXPECTED TO CONTINUE THROUGH AT LEAST THE FIRST HALF
OF THE DAY...AS A WEAK RIDGE OF HIGH PRESSURE DRIFTS EASTWARD ACROSS
THE REGION. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL
DEVELOP THIS AFTERNOON AND MAY PERSIST INTO TONIGHT AS ANOTHER WEAK
FRONTAL BOUNDARY CROSSES THE AREA. THE FRONT WILL THEN STALL SOUTH
AND EAST OF THE REGION FRIDAY...BEFORE A STRONGER FRONT APPROACHES
FROM THE WEST LATE SATURDAY BRINGING THE POTENTIAL FOR A WIDESPREAD
SOAKING RAINFALL.
&&
.HYDROLOGY...
A WEAK FRONTAL BOUNDARY WILL BRING ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS THIS AFTERNOON INTO TONIGHT. MOST AREAS WILL REMAIN
DRY...ALTHOUGH SOME LOCATIONS COULD RECEIVE A QUICK QUARTER TO HALF
INCH OF RAIN. ANY BRIEF...DOWNPOURS COULD LEAD TO TEMPORARY PONDING
OF WATER IN LOW LYING...POOR DRAINAGE AND URBAN AREAS.
A FEW MORE SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ON
FRIDAY WITH THE FRONT LINGERING ACROSS THE SOUTHEAST PORTION OF THE
HSA. A MORE WIDESPREAD RAINFALL COULD OCCUR THIS WEEKEND...AS A
FRONTAL BOUNDARY AND LOW PRESSURE SYSTEM APPROACH FROM THE MIDWEST
AND OHIO VALLEY. AT THIS TIME THE SPEED OF MOVEMENT OF THIS SYSTEM
IS UNCERTAIN...WHICH WILL HAVE AN IMPACT ON RAINFALL AMOUNTS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.EQUIPMENT...
KENX DOPPLER RADAR WILL BE OFFLINE DUE TO A REQUIRED UPGRADE THIS
MORNING WITH A RETURN TO FULL SERVICE EXPECTED BY EARLY AFTERNOON.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...JPV
NEAR TERM...BGM/JPV
SHORT TERM...JPV
LONG TERM...IAA
AVIATION...IAA
FIRE WEATHER...JPV
HYDROLOGY...JPV
EQUIPMENT...BGM
FOR THE LATEST UPDATES...PLEASE VISIT OUR WEBPAGE AT
WWW.WEATHER.GOV/ALBANY
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1016 AM EDT THU SEP 6 2012
.SYNOPSIS...
ISSUED AT 327 AM EDT THU SEP 6 2012
A RELATIVELY ACTIVE PERIOD OF WEATHER IS EXPECTED THROUGH THE END OF
THE WEEK...AS ADDITIONAL DISTURBANCES ROTATE THROUGH THE REGION. A
BRIEF BREAK IN THE ACTIVE WEATHER IS EXPECTED INTO THIS EVENING...
WITH RAIN CHANCES INCREASING AGAIN LATER TONIGHT THROUGH FRIDAY. A
GENERALLY DRY AND MUCH COOLER WEEKEND IS EXPECTED...WITH JUST
PERHAPS A FEW LIGHT SHOWERS RETURNING FOR SATURDAY NIGHT. SLOWLY
MODERATING CONDITIONS ARE EXPECTED NEXT WORK WEEK.
&&
.UPDATE...
ISSUED AT 1016 AM EDT THU SEP 6 2012
FAIRLY QUIET WEATHER ACROSS THE REGION THROUGH THE DAY...BUT NOT
WITHOUT OUR FAIR SHARE OF "ISSUES" AS WE HEAD INTO THE AFTERNOON.
THE FIRST IS CLOUD COVER. HAVE SEEN QUITE THE PESKY PLUME OF BOTH
LOW AND MID CLOUDS ACROSS PARTS OF NORTHERN LOWER SINCE JUST
BEFORE SUNRISE...WITH THE MID CLOUDS BEING DRIVEN MAINLY BE
REMNANT WEAKISH INSTABILITY ABOVE A STEEPER 775-700MB LAPSE RATE
PLUME (SEE 12Z APX RAOB FOR HINTS OF THIS). EARLIER LAKE MICHIGAN
CONVECTION (AND SUBSEQUENT MID CLOUD FOR THAT MATTER) WAS LIKELY
DRIVEN BY LOW LEVEL PARCELS BEING LOFTED INTO THIS REMAINING
SKINNY INSTABILITY PLUME...WITH SOME HINTS THIS OCCURRED DUE TO A
NOTABLE MID LAKE (LAND BREEZE INDUCED?) CONVERGENCE AXIS. SUSPECT
THESE PESKY CLOUDS WILL HANG AROUND FOR A WHILE INTO
MIDDAY...WHILE LOWER STUFF GRADUALLY MIXES OUT. WILL PROBABLY SEE
AN OK AMOUNT OF DIURNAL CU DEVELOPMENT AS WELL...PARTICULARLY OVER
NORTHEAST LOWER AND INTERIOR EASTERN UPPER WHERE MEAN LOW LEVEL
WESTERLY FLOW WILL FAVOR BEST LAKE BREEZE CONVERGENCE.
WILL ALSO BE WATCHING WIND/DEW POINT TRENDS INTO THE AFTERNOON.
PER UPSTREAM POST-FRONTAL OBS IN MINNESOTA YESTERDAY...MIXING
ENDED UP DEEPER THAN PROGGED...AND SUSPECT THIS WILL BE THE CASE
HERE AS WELL (12Z APX RAOB LOOKS A LOT LIKE 12Z MPX ONE
YESTERDAY). AS SUCH...HAVE BOOSTED GUSTS THIS AFTN ALONG WITH
LOWERING DEW POINTS INTO THE 40S IN SPOTS. THIS STILL WON`T BE
ENOUGH TO GIVE US ANY BIG FIRE WX ISSUES...BUT MIN RH VALUES
SHOULD DIP WELL INTO THE 30S.
FINALLY...WILL HAVE TO WATCH THE POTENTIAL FOR SOME ISOLATED AFTN
SHOWERS OVER MAINLY EASTERN UPPER. THIS AREA WILL BE FAVORED BY
BEST LOW LEVEL CONVERGENCE BENEATH A SHARPER UPPER COOL POOL. PER
LATEST RUC FORECAST RAOBS...CAN ENVISION SQUEEZING OUT ENOUGH CAPE
(MAYBE 100-200J/KG) TO GIVE US A FEW SNEAKY SHOWERS. MEANWHILE...
DON`T FORESEE THIS HAPPENING ACROSS NORTHEAST LOWER WHERE RESIDUAL
CAP IN PLACE SHOULD KEEP THINGS IN CHECK. CERTAINLY WILL HAVE TO
KEEP AN EYE ON THIS THOUGH.
HAVE RAISED GOING HIGHS A COUPLE OF DEGREES PER LATEST TRENDS AND
LACK OF ANY REAL ONGOING ADVECTION TODAY. WILL SEE READINGS RANGE
FROM THE MID 70S FAR NORTH TO AROUND 80 ACROSS MANY SPOTS FOR
NORTHERN LOWER.
UPDATE ISSUED AT 621 AM EDT THU SEP 6 2012
FAIRLY QUIET CONDITIONS THIS MORNING WITH CLEAR TO PARTLY CLOUDY
SKIES AND PATCHY DENSE FOG OUT THERE. HOT SPOT OF CONVECTION OVER
CENTRAL LAKE MICHIGAN...JUST WEST OF MANISTEE OVER THE LAST FEW
HOURS...WITH A NUMBER OF SMALL SHOWERS (EVEN SOME THUNDER) COMING
ONSHORE IN THAT AREA BUT DYING SOON AFTER. IN ANY EVENT...HAVE
ISOLATED SHOWERS/THUNDER IN THAT AREA THROUGH 12Z...HOPEFULLY THAT
WILL BE LONG ENOUGH.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 327 AM EDT THU SEP 6 2012
MID-UPPER LOW LOCATED OVER NRN MANITOBA/NW ONTARIO WITH BROAD
TROUGHING SPANNING MUCH OF THE NRN CONUS. SHORT WAVE IMPULSE
DROPPING DOWN INTO THE NRN ROCKIES ACCOMPANIED BU A DEVELOPING
WEST-EAST UPPER JET CORE ACROSS THE NRN PLAINS. SHORT WAVE IMPULSE
AND UPPER JET FEATURE WILL BE THE NEXT WEATHER MAKER FOR THE WESTERN
GREAT LAKES...AS IT PUNCHES INTO THE REGION AND ULTIMATELY CARVES
OUT A FAIRLY SUBSTANTIAL TROUGH THROUGH THE WEEKEND. IN THE
MEANTIME...IN THE WAKE OF YESTERDAYS COLD FRONT...ILL DEFINED HIGH
PRESSURE AND A FAIRLY DRY AIRMASS IN THE PROCESS OF BUILDING INTO
THE REGION.
TODAY...OVERALL QUIET AS ILL-DEFINED HIGH PRESSURE SLIDES THROUGH
THE REGION. THAT SAID...THERE IS A LITTLE BIT OF ELEVATED
INSTABILITY WORKING INTO THE REGION FROM THE WEST...EVIDENCED BY THE
POCKETS OF MID CLOUD (ACCAS). WEAK SYNOPTIC FORCING ACROSS LOWER
MICHIGAN AND STRONGER MID LEVEL FLOW HAS SPARKED A LONE ELEVATED
SHOWER OVER CENTRAL LAKE MICHIGAN. WILL KEEP AN EYE ON THAT TO SEE
IF WE HAVE TO ADD ISOLATED POPS TO THE FORECAST ALONG THE M-55
CORRIDOR THIS MORNING. OTHERWISE...COOLER AIR ALOFT/DEEPER MIXED
LAYER AND DAYTIME HEATING WILL LEAD TO SCT-BKN CU DEVELOPMENT TODAY.
FORECAST SOUNDINGS DONT SHOW ENOUGH INSTABILITY TO WARRANT
POPS...BUT DAY CREW WILL NEED TO WATCH FOR ANY HEATING OF THE DAY
INDUCED SHOWERS POPPING UP.
TONIGHT...QUIET EVENING. THEN...AFOREMENTIONED UPSTREAM SHORT WAVE
IMPULSE AND DEVELOPING UPPER JET STREAK WILL ADVANCE ACROSS THE
UPPER MIDWEST AND BEGIN TO PUNCH ACROSS NRN MICHIGAN BY FRIDAY
MORNING. THIS LEADS TO A STRENGTHENING BAND OF MID LEVEL
F-GEN/RESULTING QG-UPWARD ASCENT PUNCHING ACROSS NRN MICHIGAN BY
MORNING (AND EVENTUALLY THROUGH LOWER MICHIGAN ON FRIDAY). CURRENT
TIMING SUGGESTS MOST OF TONIGHT WILL BE DRY...WITH RAINFALL
SPREADING THROUGH EASTERN UPPER MICHIGAN/TIP OF THE MITT TOWARD
MORNING. HAVE TWEAKED FORECAST POPS/WEATHER ACCORDINGLY.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 327 AM EDT THU SEP 6 2012
RATHER BUSY EXTENDED FORECAST...ESPECIALLY DURING THE EARLY
PERIODS...AS ELONGATED CENTRAL CANADA CENTERED TROUGHING MOVES
EAST...PARTIALLY A BY-PRODUCT OF STRONG SHORTWAVE TROUGH ROUNDING
ITS BASE INTO THE LAKES REGION FRIDAY INTO THE WEEKEND. LACK OF
DOWNSTREAM BLOCKING AND MAINTENANCE OF UPSTREAM KICKER SYSTEMS
EXPECTED TO KEEP THIS TROUGH AXIS FAIRLY TRANSIENT...A SOLUTION
GENERALLY NOW WELL GREED UPON BY NEARLY ALL AVAILABLE GUIDANCE.
PATTERN LOOKS TO BECOME A TOUCH MORE ZONAL DURING THE COURSE OF NEXT
WORK WEEK...ONCE AGAIN PROPELLING THE MOST "ACTIVE" WEATHER TO
REGIONS NORTH OF THE BORDER. FORECAST CONCERNS CENTER ON IMPACTS OF
LATE WEEK SYSTEM (BOTH SYNOPTIC AND LAKE ENHANCED/EFFECT RAIN
CHANCES)...AS WELL AS TEMPERATURE AND CLOUD TRENDS THROUGHOUT THE
PERIOD.
STILL APPEARS A DECENT BAND OF MUCH NEEDED RAINFALL WILL DRIFT
SOUTHEAST ACROSS THE NORTH WOODS FRIDAY...COURTESY OF AFOREMENTIONED
APPROACHING STRONG WAVE ENTICING LOW/MID LEVEL FGEN RESPONSE...ALL
OVER-TOPPED BY DECENT EXIT REGION UPPER JET DYNAMICS. DESPITE DECENT
AGREEMENT AMONGST GUIDANCE ON THE ABOVE...RECENT DRY STRETCH OF
WEATHER AND OVERALL THEME OF UNDER-PERFORMING RAIN SYSTEMS LATELY
PREVENTS A CATEGORICAL MENTION (INHERITED LIKELY WILL SUFFICE...WITH
JUST SOME COSMETIC CHANGES ON TIMING). POTENTIAL DOES EXIST FOR AT
LEAST SOME DECENT RAINFALL AS ABOVE DYNAMICS INTERACT WITH AN
APPRECIABLY MOIST AIRMASS (PWAT VALUES AOA 1 INCH). SIGNIFICANT
QUESTIONS START TO ARISE FRIDAY NIGHT INTO SATURDAY AS INITIAL
POSITIVELY TILTED TROUGH CONTINUES TO DIG AND TAKE ON A MORE NEUTRAL
APPEARANCE BY SATURDAY. MODELS CONTINUE TO STRUGGLE WITH JUST HOW
PROGRESSIVE THE ABOVE UNFOLDS...WITH NOW THE NEW 00Z UKMET AND ECMWF
THE MOST AGGRESSIVE IN DRIVING SIGNIFICANT EASTERN LAKES SURFACE LOW
DEVELOPMENT (AND HENCE A SLOWER SOLUTION)...RESULTING IN WIDESPREAD
RAINS HOLDING ON FRIDAY NIGHT INTO SATURDAY FOR NORTHEAST LOWER.
VAST MAJORITY OF OTHER PROGS...INCLUDING THE PREVIOUS MUCH SLOWER
AND WRAPPED-UP NAM-WRF...MORE PROGRESSIVE...DRIVING THE RAIN THREAT
EAST OF THE REGION BY LATER FRIDAY NIGHT. INHERITED FORECAST KINDA
LEFT OPEN THE POSSIBILITY OF THIS SLOWER SCENARIO...AT LEAST KEEPING
SOME RAIN MENTION ACROSS THE SOUTHEAST. GIVEN UNCERTAINTY...CAN
SIMPLY FIND ON COMPELLING ARGUMENT TO DEVIATE FROM THIS PHILOSOPHY.
WILL ALSO NEED TO WATCH FOR SOME LIGHT NORTHERN LAKE MICHIGAN
ENHANCED SHOWERS FRIDAY NIGHT AS NNW FLOW CAA DROPS H85 TEMPERATURES
INTO THE LOWER AND MIDDLE SINGLE DIGITS. ASSUMING THE FASTER IDEA
WORKS OUT...EXPECTING TO SEE A DRY SATURDAY WITH INITIAL LAKE DRIVEN
MORNING CLOUDS GIVING WAY TO WIDESPREAD INTERIOR SC FIELD AS THERMAL
TROUGH LINGERS OVERHEAD. COMBINATION OF CLOUDS/RAIN AND FLOW
BECOMING INCREASINGLY DIRECTED OUT OF CANADA WILL KEEP READINGS BOTH
FRIDAY AND SATURDAY SIGNIFICANTLY COOLER THAT WHAT HAS BEEN OBSERVED
LATELY...WITH HIGHS FRIDAY IN THE 60S AND LOWER 70S...COOLING
FURTHER INTO THE 60S AREA-WIDE SATURDAY.
EVIDENCE CONTINUES TO SUPPORT ADDITIONAL ENERGY DIVING SOUTH ON
BACKSIDE OF HOPEFULLY THEN DEPARTING TROUGH SATURDAY NIGHT...PERHAPS
KICKING OFF A FEW ADDITIONAL LIGHT SHOWERS (LAKE ENHANCED?). BARRING
ANY SIGNIFICANT SURPRISES TO DEPARTURE OF EASTERN LAKES
TROUGHING...REST OF THE FORECAST SHAPING UP TO BE A QUIET ONE AS
FLOW BECOMES MORE ZONAL AND ACTIVE WEATHER SHIFTS NORTH INTO CANADA.
TRENDS STILL SUPPORTING A MOISTURE STARVED COLD FRONTAL PASSAGE
WEDNESDAY...WITH A LOW END SHOWER THREAT ACCOMPANYING IT.
OTHERWISE...MULTI-PERIODS OF DRY WEATHER IS EXPECTED ALONG WITH A
SLOW MODERATING TREND. HIGHS STILL STUCK IN THE 60S ON SUNDAY WILL
GRADUALLY WARM WELL INTO THE 70S BY TUESDAY AND WEDNESDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 621 AM EDT THU SEP 6 2012
BRIEF PERIOD OF MVFR OR IFR CONDITIONS POSSIBLE AT APN/PLN EARLY
THIS MORNING...DUE TO SHALLOW FOG. VFR CONDITIONS OVERALL TODAY
ALTHOUGH SCT-BKN CU DECK WILL DEVELOP MY MIDDAY. DONT THINK WE GET
ENOUGH VERTICAL DEVELOPMENT OF SHOWERS TO POP...BUT NE LOWER
MICHIGAN WOULD STAND THE BEST CHANCE FOR THAT TO OCCUR.
QUIET...CLEAR TO PARTLY CLOUDY SKIES THIS EVENING. THICKENING MID
CLOUD ARRIVES OVERNIGHT AS MID LEVEL IMPULSE AND UPPER JET STREAK
BEGINS TO NOSE INTO THE REGION. RAIN WITH THIS NEXT FEATURE...BUT
NOT REACHING THE TERMINAL SITES UNTIL AFTER 12Z FRIDAY.
&&
.MARINE...
ISSUED AT 327 AM EDT THU SEP 6 2012
NO MARINE HEADLINES NEEDED AT THIS POINT WITH LIGHTER NW-WESTERLY
WINDS THROUGH TODAY...AND MORE VARIABLE WINDS TONIGHT. SHARP
TROUGH AXIS WILL PASS THROUGH NRN MICHIGAN LATER IN THE DAY
FRIDAY. BEHIND THIS FEATURE...GUSTY NW WINDS WILL DEVELOP LATE
FRIDAY AND FRIDAY NIGHT...WITH SMALL CRAFT HEADLINES POSSIBLE
DURING THAT TIME.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...LAWRENCE
SYNOPSIS...MB
SHORT TERM...BA
LONG TERM...MB
AVIATION...BA
MARINE...BA
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
628 AM CDT THU SEP 6 2012
.SHORT TERM...
ISSUED AT 332 AM CDT THU SEP 6 2012
(TODAY THROUGH FRIDAY NIGHT)
STILL EATING CROW AFTER YESTERDAY`S BUSTED FORECAST...AND IT`S A
BITTER BIRD. THE COLD FRONT HAS MADE IT THROUGH KIRKSVILLE BUT IS
TAKING ITS TIME DRIFTING THROUGH THE NORTHWEST PORTION OF THE CWFA.
CURRENT THINKING IS THAT THE FRONT WILL CONTINUE DRIFTING SOUTHEAST
BUT WILL PROBABLY NOT CLEAR THE SOUTHERN PORTION OF THE CWFA BEFORE
AFTERNOON. RAP AND HRRR DEVELOP DECENT INSTABILITY IN EXCESS OF
2000 J/KG WITH LITTLE OR NO CAP. HAVE ADDED POPS SOUTH OF THE STL
METRO AREA ACROSS THE EASTERN OZARKS. ALSO...SINCE THE COLD AIR
ADVECTION IS SOMEWHAT LACKING FROM PREVIOUS FORECASTS...HAVE BUMPED
UP TEMPS A COUPLE OF DEGREES TODAY.
ATTENTION TURNS TO THE STRONG SHORTWAVE JUST NOW DROPPING INTO THE
CONUS FROM SOUTHEAST CANADA AND THE RESULTING STORM WHICH WILL MOVE
THROUGH FRIDAY AND FRIDAY NIGHT. THE WAVE`S PRESENTATION ON WATER
VAPOR IMAGERY IS PRETTY IMPRESSIVE FOR EARLY SEPTEMBER. THIS IS
ENCOURAGING FOR THE FORECAST. LATEST GUIDANCE KEEPS MUCH OF THE
AREA DRY TONIGHT...PRETTY MUCH ALL EXCEPT NORTHEAST MISSOURI AND
WEST CENTRAL ILLINOIS. CAN`T QUITE BRING MYSELF TO PULL POPS OUT OF
THE REST OF THE AREA THO...SO HAVE LEFT THEM BE. ALL GUIDANCE HAS
THE SHORTWAVE DIVING INTO THE PLAINS FRIDAY MORNING AND THE
ASSOCIATED COLD FRONT MOVING THROUGH KIRKSVILLE BY AROUND 18Z. SPC
HAS US OUTLOOKED IN A SLIGHT RISK AND THIS LOOKS GOOD GIVEN THAT THE
NAM DEVELOPS INSTABILITY IN EXCESS OF 3000 J/KG AND PLENTY OF DEEP
LAYER SHEAR. HAVE BUMPED UP POPS TO OCCASIONAL DURING THE AFTERNOON
AND EARLY EVENING FOR PARTS OF THE AREA. LATEST GUIDANCE HAS THE
FRONT MOVING THOUGH FASTER THAN EARLIER FORECAST...SO HAVE CUT BACK
ON POPS AFTER MIDNIGHT.
CARNEY
&&
.LONG TERM...
ISSUED AT 358 AM CDT THU SEP 6 2012
(SATURDAY THROUGH WEDNESDAY)
PRIMARY CHANGE TO THE FORECAST FOR THE LONG TERM IS TO INCREASE HIGH
TEMPERATURES A BIT THIS WEEKEND AND EARLY NEXT WEEK. ALL OF THE
MODELS DROP A STRONG RIDGE INTO THE AREA THIS WEEKEND BEHIND THE
FRONT. WHEN WE INITIALLY BEGAN SEEING THIS STORM SYSTEM IN THE
MODELS SEVERAL DAYS AGO...THEY DEVELOPED A CLOSED LOW OVER THE GREAT
LAKES/OHIO VALLEY REGION. THE PAST FEW RUNS THE MODELS HAVE BECOME
PROGRESSIVE WITH THE WAVE. THIS SHOULD MEAN THAT INSTEAD OF
CONSIDERABLE CLOUDS AND WIDELY SCATTERED SHOWERS ON SATURDAY...IT
SHOULD BE MOSTLY SUNNY AND DRY. WITH THE MORE PROGRESSIVE
SOLUTION...THE WARM UP BACK TO NEAR NORMAL TEMPERATURES SHOULD OCCUR
MORE QUICKLY ON SUNDAY INTO EARLY NEXT WEEK. UPPER LEVEL RIDGE
BUILDS BACK INTO THE AREA BY TUESDAY. ANOTHER COLD FRONT LOOKS TO
BE APPROACHING THE AREA ON WEDNESDAY...BUT HAVE NOT PUT ANY POPS IN
THE FORECAST AT THIS TIME AS THE STRONG SURFACE RIDGE WHICH WILL
BRING US THIS WEEKEND`S COOL WEATHER LOOKS LIKE IT WILL LAY OUT DOWN
ACROSS THE SOUTHERN U.S. AND BLOCK ANY MOIST RETURN FLOW FROM THE
GULF.
CARNEY
&&
.AVIATION...
ISSUED AT 614 AM CDT THU SEP 6 2012
THE COLD FRONT CONTINUES TO MOVE SOUTH AND HAS PASSED THROUGH
KCOU AND KUIN. LOW LEVEL MOISTURE IS ABUNDANT AND SOME PATCHY FOG
HAS DEVELOPED...MAINLY IN LOW LYING AREAS. THIS SHOULD BURN OFF
PRETTY QUICK AFTER SUNRISE...WITH VISIBILITIES RAPIDLY IMPROVING.
CUMULUS WILL DEVELOP THIS MORNING AND INTO THE AFTERNOON AROUND
7KFT AS PLENTY OF 850MB MOISTURE REMAINS OVER THE AREA.
WIND WILL VEER FROM NORTH TO SOUTHEAST AS THE FRONT SETTLES TO OUR
SOUTH. MID LEVEL MOISTURE AND PRECIPITATION CHANCES RAPIDLY
INCREASE LATE TONIGHT AND TOMORROW MORNING AS UPPER LEVEL
DISTURBANCE MOVES TOWARD THE MIDWEST.
SPECIFICS FOR KSTL...
COLD FRONT FORECAST TO MOVE THROUGH THE TERMINAL SHORTLY AFTER 12Z
WITH WIND SWITCHING TO THE NORTH. DIURNAL SCT CU SHOULD DEVELOP
AROUND 7KFT TODAY. WIND TO VEER AROUND TO THE SOUTHEAST BY FRIDAY
MORNING...WITH PRECIPITATION CHANCES INCREASING AFTER 12Z.
CVKING
&&
.PRELIMINARY POINT TEMPS/POPS...
ST LOUIS 91 71 85 58 / 5 30 80 70
QUINCY 86 66 78 53 / 5 60 70 40
COLUMBIA 91 69 80 54 / 10 50 80 40
JEFFERSON CITY 91 69 83 56 / 10 40 80 50
SALEM 89 67 85 59 / 5 20 80 80
FARMINGTON 92 69 85 58 / 20 20 80 80
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1135 AM EDT THU SEP 6 2012
.SYNOPSIS...
WEAK COLD FRONT ARRIVES THIS EVENING. HIGH PRESSURE FRIDAY. STRONG
COLD FRONT SATURDAY. HIGH PRESSURE SUNDAY INTO THE NEXT WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
11 AM UPDATE...NO SIGNIFICANT CHANGES.
600AM UPDATE...
NO SIGNIFICANT CHANGES MADE WITH THIS UPDATE...JUST TWEAKED
INITIAL SKY GRIDS.
PREVIOUS DISCUSSION BELOW...
SHRA CONT TO INCREASE ACROSS N CARTER AND S GREENUP AS OF
0630Z...WITH NEARLY STATIONARY MOTIONS. BUMPED UP POPS INTO LKLY
NEXT COUPLE HRS ACROSS NE KY COUNTIES. WILL BE MONITORING RAINFALL
AS WELL.
PREVIOUS DISCUSSION BELOW...
SHRA LIGHTING UP ON RADAR AT 06Z ACROSS W ZONES...ASSOCIATED WITH
S/W TROF AND EMBEDDED VORT MAX. RUC TRACKS THIS SLOWLY NE THRU CWA
BY 13Z. HAVE SOME LOW POPS WITH THIS AS IT DOES SO. BACK EDGE OF
CLDS WILL SLOWLY PUSH THRU PORTIONS OF SE OH BY 08Z...TAKING TO
NEAR SUNRISE TO GET INTO CENTRAL WV LOWLANDS. FURTHER COMPLICATING
SKY COVER IS LOW STRATUS THAT IS POISED TO DEVELOP ACROSS ALONG
AND E OF I79 CORRIDOR...BASED ON MODEL PROJECTIONS. THINK THIS MAY
END UP MORE IN MTNS AND S COAL FIELDS. SOME RVR VALLEY FG THROWN
IN AS WELL...ESPECIALLY FOR AREAS THAT MANAGE TO CLR.
WILL TRY TO SCT OUT ANY LOW CLDS BY MID MORNING. WILL LOOK FOR MTN
SHRA AND A FEW TSRA TO DEVELOP WITH HEATING AND WEAK OROGRAPHIC
LIFT. WILL CARRY CHC POPS THERE...TAILING OFF TO SCHC BACK TO I79
CORRIDOR. OTHERWISE...WEAK FRONT DROPPING SE THRU UPR OH VALLEY
LOOKS TO BE DELAYED UNTIL LATE AFTN FOR SE OH ZONES BEFORE BECOMING
RATHER DIFFUSE TONIGHT. HAVE ONLY SCHC POPS WITH THIS AS OVERALL
SETUP LOOKS RATHER MEAGER.
WILL ROLL A TICK OR TWO ABV WARMEST GUIDANCE FOR HIGHS TDY BASED
ON RECENT PERFORMANCE AND NEAR HIGH SIDE OF GUIDANCE FOR LOWS
TONIGHT.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
MODELS HAVE COME INTO DECENT AGREEMENT THROUGHOUT THE PERIOD. MODELS
SHOW HIGH PRESSURE FOR FRIDAY. MESO NAM IS TRYING TO CREATE A FEW
SHOWERS IN THE MOUNTAINS...BUT BELIEVE THAT THE 700 MB AIR IS TOO
DRY. A FAST MOVING COLD FRONT THEN PUSHES THROUGH ON SATURDAY. WILL
FINE TUNE POPS FOR BETTER TIMING. HIGH PRESSURE THEN TAKES OVER
SATURDAY NIGHT INTO THE NEXT WORK WEEK. WILL REMOVE POPS SATURDAY
NIGHT THROUGH SUNDAY NIGHT.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
MADE WHOLESALE CHANGES TO THE LONG TERM FORECAST AS MODELS COMING
INTO BETTER AGREEMENT THAN YESTERDAY...NOW SHOWING OPEN WAVE
SWINGING THROUGH OVER THE WEEKEND...AND A THING OF THE PAST AS WE
HEAD INTO THE WORK WEEK. LINGER CHANCE AND SLIGHT CHANCE POPS
THROUGH SUNDAY...MOVING OUT SUNDAY NIGHT AS THE UPPER TROUGH MOVES
EAST AND OUT TO SEA. THIS WILL PROVIDE A MAINLY DRY FORECAST FOR THE
REST OF THE LONG TERM. DID NOT INCLUDE ANY POPS FOR THE WORK WEEK AT
THIS TIME DUE TO LACKING MOISTURE...BUT WITH NORTHWEST FLOW IT MAY
BE POSSIBLE TO GET A LITTLE SHORTWAVE RIPPLE THAT COULD POP A SHOWER
OR TWO AT SOME POINT. TEMPERATURES WILL START OFF BELOW NORMAL ON
MONDAY...WITH A GRADUAL WARMING TREND TO NEAR NORMAL BY MID TO LATE
WEEK AS UPPER RIDGE MOVES INTO SOUTHERN PLAINS.
&&
.AVIATION /16Z THURSDAY THROUGH MONDAY/...
A WEAK DRY COLD FRONT WILL DROP SE INTO THE OH VALLEY THIS
AFTN...AND DISSIPATE AS IT COMES INTO NORTHERN PORTIONS OF CWA LATER
THIS EVENING. LINGERING MVFR CLOUDS SOUTH A HTS-CRW LINE WILL
SCATTER OUT TO A VFR CU FIELD BY 18Z...OTHERWISE VFR SCT CU.
IDEAL RADIATION COOLING NIGHT UNDER WEAK HIGH PRESSURE AND CLEAR
SKIES...WILL LEAD TO RIVER AND VALLEY IFR/LIFR FOG 06Z TO 12Z.
AFTER 12Z FRIDAY...BECOMING VFR MOSTLY CLEAR AROUND 14Z.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY...
FORECAST CONFIDENCE: HIGH.
ALTERNATE SCENARIOS: TIMING AND DENSITY OF FOG AND/OR LOW STRATUS
MAY VARY TONIGHT.
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 14 15 16 17 18 19 20 21 22 23 00 01
EDT 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY M M M M H H H H H H H H
EKN CONSISTENCY H H H H H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 18Z FRIDAY...
IFR FOG EXPECTED AT SOME TERMINALS 09 TO 12Z THURSDAY. BRIEF IFR
POSSIBLE IN THUNDERSTORMS SATURDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30
NEAR TERM...JMV/30
SHORT TERM...RPY
LONG TERM...MZ
AVIATION...JMV
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
952 AM EDT THU SEP 6 2012
.SYNOPSIS...
A WEAK COLD FRONT WILL DRIFT SOUTHEAST ACROSS THE AREA LATER TODAY
INTO TONIGHT. A STRONGER COLD FRONT WILL CROSS THE REGION FRIDAY
NIGHT. HIGH PRESSURE OVER THE PLAINS SUNDAY WILL MOVE UP THE OHIO
VALLEY MONDAY AND TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A WEAK COLD FRONT WILL SAG SOUTHWARD INTO THE REGION TODAY.
CONVERGENCE ALONG THE FRONT AND AFTERNOON HEATING SHOULD LEAD TO
SOME ISOLATED TO SCATTERED THUNDERSTORMS. IF ANY STRONG STORMS CAN
DEVELOP THERE WOULD BE A THREAT OF STRONGER WIND GUSTS.
OTHERWISE EXPECT TO SEE SOME AFTERNOON CUMULUS WITH SOME MIDDLE
LEVEL CONVECTIVE DEBRIS. HIGHS THIS AFTERNOON WILL BE IN THE MIDDLE
80S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
LINGERING THREAT FOR EVENING CONVECTION PER PREVIOUS DISCUSSION THEN
AIRMASS SETTLES DOWN DUE TO LOSS OF DAYTIME HEATING AND SLIGHTLY
DRIER AIR DRIFTING SE INTO THE AREA. SOME PATCHY FOG COULD DEVELOP.
DRY PERIOD WILL BE SHORT-LIVED. UPPER TROUGH DIGS SE INTO THE AREA
FOR SAT. A SURFACE WAVE OF LOW PRESSURE IS INDUCED ALONG A COLD
FRONT THAT WILL MOVE THROUGH FRI NIGHT. GOOD DYNAMICS SHOULD LEAD TO
WIDESPREAD SHRA/TSRA SPREADING EAST ACROSS THE CWA STARTING LATER
FRI INTO FRI NIGHT. SOME OF THE RAIN COULD BE LOCALLY HEAVY FRI
NIGHT INTO EARLY SAT. THE THREAT FOR THUNDER SHOULD SHIFT INTO JUST
THE EAST BY SAT MORNING.
COLDER AIR ALOFT WILL LEAD TO LAKE ENHANCEMENT FOR SHRA IN THE
SNOWBELT LATER SAT AND SAT NIGHT. A LITTLE THUNDER COULD OCCUR WITH
THE LAKE EFFECT CONVECTION.
HIGH PRESSURE BEGINS TO BUILD IN FROM THE WEST ON SUN AND THE UPPER
TROUGH AXIS BEGINS TO SHIFT EAST OF THE AREA DURING THE AFTERNOON.
THIS SHOULD KEEP THE SHRA THREAT LIMITED TO MOSTLY JUST THE EAST.
A LINGERING SHRA OR TWO COULD HANG AROUND OVER THE SNOWBELT SUN
NIGHT...OTHERWISE THE REST OF THE AREA SHOULD BE DRY AS DRIER AIR
AND SUBSIDENCE TAKE CONTROL.
NOTICEABLY COOLER TEMPS WILL ARRIVE FOR SAT AND CONTINUE SUN WITH
HIGHS MOSTLY IN THE 60S. LOWS BY SUN NIGHT SHOULD MAINLY BE IN A 50
TO 55 RANGE AS CLOUDS BEGIN TO BREAK UP.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
A MODERATING TREND IN TEMPERATURES FOR THE PERIOD. HIGH PRESSURE
WILL BE OVER THE AREA ON MONDAY AND THEN IT WILL MOVE EAST AND THE
SOUTHERLY FLOW WILL ALLOW TEMPERATURES TO WARM BACK TO NEAR NORMAL
LEVELS. DRY FOR THE PERIOD. EVEN THOUGH ON MONDAY THE LAKE AND 850
MB TEMPERATURE DIFFERENCE WILL BE NEAR 15C THE FLOW WILL BE SO WEAK
THAT JUST SOME CLOUDS WILL BE AROUND AND NO SHOWERS. A COLD FRONT
WILL BE MOVING THROUGH WEDNESDAY NIGHT BUT AT THIS TIME THAT MAY BE
DRY.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AREAS OF FOG AND ISOLATED STRATUS WILL BURN OFF AFTER SUNRISE.
TODAYS WEATHER WILL BE CAUSED BY A COLD FRONT THAT WILL MOVE
THROUGH. AT 11Z THE COLD FRONT WAS LOCATED FROM WESTERN LOWER
MICHIGAN TO EAST OF CHICAGO TO NORTHERN MISSOURI. SOME CLOUDS WERE
ALONG IT. THE FRONT WILL MOVE THROUGH THE REGION MAINLY DURING THE
AFTERNOON. HOWEVER...SOME SHOWERS COULD DEVELOP OVER NORTHWEST
OHIO THIS MORNING. THE BEST CHANCE FOR THUNDER WILL BE FROM CLE
AND MFD SOUTHEAST. THE HRRR MODEL SEEMS TO HAVE A GOOD HANDLE ON
THINGS. THE BEST CHANCE TO HAVE THUNDER AT A TAF SITE WILL BE CAK
AND YNG. SINCE THE FRONT WILL BE THE CAUSE OF THE THUNDERSTORMS
THEY SHOULD BE IN A LINE WITH SOME ISOLATED CONVECTION AHEAD OF
IT.
CLOUDS WILL DECREASE TONIGHT. THE MODELS ARE VERY SLOW IN
DECREASING THE MOISTURE...THIS MAY BE TOO SLOW BASED ON WHAT IS
GOING ON NOW UPSTREAM. SOMETIMES AFTER A FRONTAL PASSAGE MVFR
CEILINGS DEVELOP. IN THIS CASE THE WIND SHIFT IS BRIEF. THE MODELS
DO HINT AT SOME MOISTURE NEAR ERIE...SO KEPT SOME SCATTERED
LOW CLOUDS IN THAT AREA. OTHERWISE THE AIRMASS IS TRYING TO DRY
OUT...SO NOT EXPECTING FOG AT THE TAF SITES...HOWEVER...PATCHY
MVFR FOG WILL OCCUR ELSEWHERE.
.OUTLOOK...NON VFR POSSIBLE FRIDAY NIGHT INTO SUNDAY.
&&
.MARINE...
A WEAK COLD FRONT WILL BE MOVING ACROSS THE LAKE TODAY. A SOUTHWEST
TO WEST FLOW AHEAD OF THE FRONT AND THEN A LIGHT NORTHWEST BEHIND
THE FRONT. NOT EXPECTING CONDITIONS TO MEET SMALL CRAFT ADVISORY
CONDITIONS. A FEW THUNDERSTORMS ON THE LAKE COULD BE STRONG LATER
TODAY. HIGH PRESSURE WILL MOVE ACROSS THE LAKE TONIGHT.
FRIDAY NIGHT THROUGH SUNDAY COULD BE INTERESTING ON THE LAKE. A COLD
FRONT WILL MOVE ACROSS THE LAKE FRIDAY NIGHT WITH A NORTHWEST TO
NORTH FLOW FOR THE WHOLE WEEKEND. THE WINDS COULD BE STRONG ENOUGH
ESPECIALLY LATE FRIDAY NIGHT INTO SATURDAY TO PROMPT A SMALL CRAFT
ADVISORY ESPECIALLY ON THE EAST END OF THE LAKE. DETAILS ARE NOT
CLEAR AT THIS TIME. THE LAKE AND 850 MB TEMPERATURE DIFFERENCE WILL
BE AROUND 15C FOR MOST OF SATURDAY AND SUNDAY AND WITH PLENTY OF
MOISTURE SOME COLD AIR WATERSPOUTS AND FUNNELS ARE QUITE POSSIBLE.
HIGH PRESSURE WILL MOVE ACROSS THE LAKE MONDAY AND THEN A SOUTHERLY
FLOW WILL DEVELOP FOR TUESDAY THROUGH WEDNESDAY. NOT EXPECTING SMALL
CRAFT ADVISORY CRITERIA DURING THIS PERIOD.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ADAMS
NEAR TERM...MULLEN
SHORT TERM...ADAMS
LONG TERM...KIELTYKA
AVIATION...KIELTYKA
MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
746 AM EDT THU SEP 6 2012
.SYNOPSIS...
A WEAK COLD FRONT WILL DRIFT SOUTHEAST ACROSS THE AREA LATER TODAY
INTO TONIGHT. A STRONGER COLD FRONT WILL CROSS THE REGION FRIDAY
NIGHT. HIGH PRESSURE OVER THE PLAINS SUNDAY WILL MOVE UP THE OHIO
VALLEY MONDAY AND TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CLOUDS ASSOCIATED WITH DIFFUSE COLD FRONT STARTING TO MOVE INTO NW
CORNER OF THE CWA. PATCHY FOG SHOULD QUICKLY DISSIPATE THIS MORNING.
WEAK COLD FRONT SHOULD CROSS THE AREA LATER TODAY INTO EARLY
TONIGHT. GOOD INSTABILITY TO BE PRESENT LATER TODAY BUT WIND SHEAR
LACKING. THUS ONLY EXPECTING ISOLATED PULSE SEVERE STORMS. SHOULD
SEE AT LEAST A FEW TSRA DEVELOP WITH THE FRONT...ESPECIALLY OVER THE
EAST HALF TO 2/3 OF THE CWA. NOT SURE WHY NAM HAS NO QPF AT ALL
ANYWHERE IN THE CWA TODAY GIVEN THE SITUATION.
ANOTHER DAY OF ABOVE NORMAL TEMPS WHICH WILL BE MADE TO FEEL EVEN
WARMER DUE TO DEWPOINTS IN THE MID TO UPPER 60S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
LINGERING THREAT FOR EVENING CONVECTION PER PREVIOUS DISCUSSION THEN
AIRMASS SETTLES DOWN DUE TO LOSS OF DAYTIME HEATING AND SLIGHTLY
DRIER AIR DRIFTING SE INTO THE AREA. SOME PATCHY FOG COULD DEVELOP.
DRY PERIOD WILL BE SHORT-LIVED. UPPER TROUGH DIGS SE INTO THE AREA
FOR SAT. A SURFACE WAVE OF LOW PRESSURE IS INDUCED ALONG A COLD
FRONT THAT WILL MOVE THROUGH FRI NIGHT. GOOD DYNAMICS SHOULD LEAD TO
WIDESPREAD SHRA/TSRA SPREADING EAST ACROSS THE CWA STARTING LATER
FRI INTO FRI NIGHT. SOME OF THE RAIN COULD BE LOCALLY HEAVY FRI
NIGHT INTO EARLY SAT. THE THREAT FOR THUNDER SHOULD SHIFT INTO JUST
THE EAST BY SAT MORNING.
COLDER AIR ALOFT WILL LEAD TO LAKE ENHANCEMENT FOR SHRA IN THE
SNOWBELT LATER SAT AND SAT NIGHT. A LITTLE THUNDER COULD OCCUR WITH
THE LAKE EFFECT CONVECTION.
HIGH PRESSURE BEGINS TO BUILD IN FROM THE WEST ON SUN AND THE UPPER
TROUGH AXIS BEGINS TO SHIFT EAST OF THE AREA DURING THE AFTERNOON.
THIS SHOULD KEEP THE SHRA THREAT LIMITED TO MOSTLY JUST THE EAST.
A LINGERING SHRA OR TWO COULD HANG AROUND OVER THE SNOWBELT SUN
NIGHT...OTHERWISE THE REST OF THE AREA SHOULD BE DRY AS DRIER AIR
AND SUBSIDENCE TAKE CONTROL.
NOTICEABLY COOLER TEMPS WILL ARRIVE FOR SAT AND CONTINUE SUN WITH
HIGHS MOSTLY IN THE 60S. LOWS BY SUN NIGHT SHOULD MAINLY BE IN A 50
TO 55 RANGE AS CLOUDS BEGIN TO BREAK UP.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
A MODERATING TREND IN TEMPERATURES FOR THE PERIOD. HIGH PRESSURE
WILL BE OVER THE AREA ON MONDAY AND THEN IT WILL MOVE EAST AND THE
SOUTHERLY FLOW WILL ALLOW TEMPERATURES TO WARM BACK TO NEAR NORMAL
LEVELS. DRY FOR THE PERIOD. EVEN THOUGH ON MONDAY THE LAKE AND 850
MB TEMPERATURE DIFFERENCE WILL BE NEAR 15C THE FLOW WILL BE SO WEAK
THAT JUST SOME CLOUDS WILL BE AROUND AND NO SHOWERS. A COLD FRONT
WILL BE MOVING THROUGH WEDNESDAY NIGHT BUT AT THIS TIME THAT MAY BE
DRY.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AREAS OF FOG AND ISOLATED STRATUS WILL BURN OFF AFTER SUNRISE.
TODAYS WEATHER WILL BE CAUSED BY A COLD FRONT THAT WILL MOVE
THROUGH. AT 11Z THE COLD FRONT WAS LOCATED FROM WESTERN LOWER
MICHIGAN TO EAST OF CHICAGO TO NORTHERN MISSOURI. SOME CLOUDS WERE
ALONG IT. THE FRONT WILL MOVE THROUGH THE REGION MAINLY DURING THE
AFTERNOON. HOWEVER...SOME SHOWERS COULD DEVELOP OVER NORTHWEST
OHIO THIS MORNING. THE BEST CHANCE FOR THUNDER WILL BE FROM CLE
AND MFD SOUTHEAST. THE HRRR MODEL SEEMS TO HAVE A GOOD HANDLE ON
THINGS. THE BEST CHANCE TO HAVE THUNDER AT A TAF SITE WILL BE CAK
AND YNG. SINCE THE FRONT WILL BE THE CAUSE OF THE THUNDERSTORMS
THEY SHOULD BE IN A LINE WITH SOME ISOLATED CONVECTION AHEAD OF
IT.
CLOUDS WILL DECREASE TONIGHT. THE MODELS ARE VERY SLOW IN
DECREASING THE MOISTURE...THIS MAY BE TOO SLOW BASED ON WHAT IS
GOING ON NOW UPSTREAM. SOMETIMES AFTER A FRONTAL PASSAGE MVFR
CEILINGS DEVELOP. IN THIS CASE THE WIND SHIFT IS BRIEF. THE MODELS
DO HINT AT SOME MOISTURE NEAR ERIE...SO KEPT SOME SCATTERED
LOW CLOUDS IN THAT AREA. OTHERWISE THE AIRMASS IS TRYING TO DRY
OUT...SO NOT EXPECTING FOG AT THE TAF SITES...HOWEVER...PATCHY
MVFR FOG WILL OCCUR ELSEWHERE.
.OUTLOOK...NON VFR POSSIBLE FRIDAY NIGHT INTO SUNDAY.
&&
.MARINE...
A WEAK COLD FRONT WILL BE MOVING ACROSS THE LAKE TODAY. A SOUTHWEST
TO WEST FLOW AHEAD OF THE FRONT AND THEN A LIGHT NORTHWEST BEHIND
THE FRONT. NOT EXPECTING CONDITIONS TO MEET SMALL CRAFT ADVISORY
CONDITIONS. A FEW THUNDERSTORMS ON THE LAKE COULD BE STRONG LATER
TODAY. HIGH PRESSURE WILL MOVE ACROSS THE LAKE TONIGHT.
FRIDAY NIGHT THROUGH SUNDAY COULD BE INTERESTING ON THE LAKE. A COLD
FRONT WILL MOVE ACROSS THE LAKE FRIDAY NIGHT WITH A NORTHWEST TO
NORTH FLOW FOR THE WHOLE WEEKEND. THE WINDS COULD BE STRONG ENOUGH
ESPECIALLY LATE FRIDAY NIGHT INTO SATURDAY TO PROMPT A SMALL CRAFT
ADVISORY ESPECIALLY ON THE EAST END OF THE LAKE. DETAILS ARE NOT
CLEAR AT THIS TIME. THE LAKE AND 850 MB TEMPERATURE DIFFERENCE WILL
BE AROUND 15C FOR MOST OF SATURDAY AND SUNDAY AND WITH PLENTY OF
MOISTURE SOME COLD AIR WATERSPOUTS AND FUNNELS ARE QUITE POSSIBLE.
HIGH PRESSURE WILL MOVE ACROSS THE LAKE MONDAY AND THEN A SOUTHERLY
FLOW WILL DEVELOP FOR TUESDAY THROUGH WEDNESDAY. NOT EXPECTING SMALL
CRAFT ADVISORY CRITERIA DURING THIS PERIOD.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ADAMS
NEAR TERM...ADAMS
SHORT TERM...ADAMS
LONG TERM...KIELTYKA
AVIATION...KIELTYKA
MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
609 AM EDT THU SEP 6 2012
.SYNOPSIS...
WEAK COLD FRONT ARRIVES THIS EVENING. HIGH PRESSURE FRIDAY. STRONG
COLD FRONT SATURDAY. HIGH PRESSURE SUNDAY INTO THE NEXT WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
600AM UPDATE...
NO SIGNIFICANT CHANGES MADE WITH THIS UPDATE...JUST TWEAKED
INITIAL SKY GRIDS.
PREVIOUS DISCUSSION BELOW...
SHRA CONT TO INCREASE ACROSS N CARTER AND S GREENUP AS OF
0630Z...WITH NEARLY STATIONARY MOTIONS. BUMPED UP POPS INTO LKLY
NEXT COUPLE HRS ACROSS NE KY COUNTIES. WILL BE MONITORING RAINFALL
AS WELL.
PREVIOUS DISCUSSION BELOW...
SHRA LIGHTING UP ON RADAR AT 06Z ACROSS W ZONES...ASSOCIATED WITH
S/W TROF AND EMBEDDED VORT MAX. RUC TRACKS THIS SLOWLY NE THRU CWA
BY 13Z. HAVE SOME LOW POPS WITH THIS AS IT DOES SO. BACK EDGE OF
CLDS WILL SLOWLY PUSH THRU PORTIONS OF SE OH BY 08Z...TAKING TO
NEAR SUNRISE TO GET INTO CENTRAL WV LOWLANDS. FURTHER COMPLICATING
SKY COVER IS LOW STRATUS THAT IS POISED TO DEVELOP ACROSS ALONG
AND E OF I79 CORRIDOR...BASED ON MODEL PROJECTIONS. THINK THIS MAY
END UP MORE IN MTNS AND S COAL FIELDS. SOME RVR VALLEY FG THROWN
IN AS WELL...ESPECIALLY FOR AREAS THAT MANAGE TO CLR.
WILL TRY TO SCT OUT ANY LOW CLDS BY MID MORNING. WILL LOOK FOR MTN
SHRA AND A FEW TSRA TO DEVELOP WITH HEATING AND WEAK OROGRAPHIC
LIFT. WILL CARRY CHC POPS THERE...TAILING OFF TO SCHC BACK TO I79
CORRIDOR. OTHERWISE...WEAK FRONT DROPPING SE THRU UPR OH VALLEY
LOOKS TO BE DELAYED UNTIL LATE AFTN FOR SE OH ZONES BEFORE BECOMING
RATHER DIFFUSE TONIGHT. HAVE ONLY SCHC POPS WITH THIS AS OVERALL
SETUP LOOKS RATHER MEAGER.
WILL ROLL A TICK OR TWO ABV WARMEST GUIDANCE FOR HIGHS TDY BASED
ON RECENT PERFORMANCE AND NEAR HIGH SIDE OF GUIDANCE FOR LOWS
TONIGHT.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
MODELS HAVE COME INTO DECENT AGREEMENT THROUGHOUT THE PERIOD. MODELS
SHOW HIGH PRESSURE FOR FRIDAY. MESO NAM IS TRYING TO CREATE A FEW
SHOWERS IN THE MOUNTAINS...BUT BELIEVE THAT THE 700 MB AIR IS TOO
DRY. A FAST MOVING COLD FRONT THEN PUSHES THROUGH ON SATURDAY. WILL
FINE TUNE POPS FOR BETTER TIMING. HIGH PRESSURE THEN TAKES OVER
SATURDAY NIGHT INTO THE NEXT WORK WEEK. WILL REMOVE POPS SATURDAY
NIGHT THROUGH SUNDAY NIGHT.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
MADE WHOLESALE CHANGES TO THE LONG TERM FORECAST AS MODELS COMING
INTO BETTER AGREEMENT THAN YESTERDAY...NOW SHOWING OPEN WAVE
SWINGING THROUGH OVER THE WEEKEND...AND A THING OF THE PAST AS WE
HEAD INTO THE WORK WEEK. LINGER CHANCE AND SLIGHT CHANCE POPS
THROUGH SUNDAY...MOVING OUT SUNDAY NIGHT AS THE UPPER TROUGH MOVES
EAST AND OUT TO SEA. THIS WILL PROVIDE A MAINLY DRY FORECAST FOR THE
REST OF THE LONG TERM. DID NOT INCLUDE ANY POPS FOR THE WORK WEEK AT
THIS TIME DUE TO LACKING MOISTURE...BUT WITH NORTHWEST FLOW IT MAY
BE POSSIBLE TO GET A LITTLE SHORTWAVE RIPPLE THAT COULD POP A SHOWER
OR TWO AT SOME POINT. TEMPERATURES WILL START OFF BELOW NORMAL ON
MONDAY...WITH A GRADUAL WARMING TREND TO NEAR NORMAL BY MID TO LATE
WEEK AS UPPER RIDGE MOVES INTO SOUTHERN PLAINS.
&&
.AVIATION /10Z THURSDAY THROUGH MONDAY/...
FG AND STRATUS WILL MIX OUT 13 TO 14Z FOR A RETURN TO VFR
CONDITIONS. AFTN HEATING WILL ALLOW FOR LOW END CU DEVELOPMENT
WITH SOME MTN CONVECTION POSSIBLE. LEFT OUT OF MTN TAFS AT THIS
DISTANCE THOUGH DUE TO LACK OF EXPECTED COVERAGE. A WEAK COLD
FRONT WILL DROP SE INTO UPR OH VALLEY THIS AFTN...TAKING UNTIL
LATE TO CROSS INTO SE OH. SOME SHRA OR TSRA POSSIBLE WITH THIS BUT
CHCS TOO LOW FOR INCLUDING IN NEAREST TAF SITE...KPKB...BEFORE
BOUNDARY BECOMES RATHER DIFFUSE IN NATURE TONIGHT E OF OH RVR.
HAVE IFR/LIFR FG FOR TONIGHT WITH A MAINLY CLR SKY EXPECTED.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY...
FORECAST CONFIDENCE: HIGH.
ALTERNATE SCENARIOS: TIMING AND DENSITY OF FOG AND/OR LOW STRATUS
MAY VARY TONIGHT.
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 L H H H H H H H H H
HTS CONSISTENCY M M M H H H H H H H H H
BKW CONSISTENCY L L L H M M M H H H H H
EKN CONSISTENCY L L H M H H H H H H H H
PKB CONSISTENCY L H H H H H H H H H H H
CKB CONSISTENCY M H H H H H H H H H H H
AFTER 12Z FRIDAY...
IFR FOG EXPECTED AT SOME TERMINALS 09 TO 12Z THURSDAY. BRIEF IFR
POSSIBLE IN THUNDERSTORMS SATURDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30
NEAR TERM...30
SHORT TERM...RPY
LONG TERM...MZ
AVIATION...30
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1050 AM EDT THU SEP 6 2012
.SYNOPSIS...
A WEAK COLD FRONT WILL MOVE SLOWLY ACROSS THE REGION TODAY AND
TONIGHT. AN UPPER TROUGH WILL FORM OVER THE GREAT LAKES AND
MIDWEST DURING THE WEEKEND THEN AMPLIFY AS IT APPROACHES
PENNSYLVANIA...BRINGING UNSETTLED WEATHER INTO THE WEEKEND. HIGH
PRESSURE WILL BUILD INTO THE AREA LATE MONDAY...BRINGING IN COOLER
TEMPERATURES...BEFORE MOVING OFF THE COAST LATER IN THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
A WEAK COLD FRONT ENTERING WESTERN PA WILL PROVIDE THE FOCUS FOR
SOME SCATTERED CONVECTION LATER TODAY. IN THE MEANTIME A WEAK
UPPER TROF IS BRINGING A FEW SPRINKLES TO MY FAR SERN ZONES AND
WILL CONTINUE OFF TO THE EAST BY EARLY AFTERNOON. BEHIND THIS
FEATURE...LATEST SATELLITE AND RUC DATA SUPPORTS A MSUNNY DAY
ACROSS THE NWRN 2/3 OR SO OF THE FCST AREA...WITH INCREASING
SUNSHINE FOR THE AFTERNOON ACROSS THE SE PART OF THE CWA.
THE SUNSHINE AND MDL 8H TEMPS ARND 17C WILL ALLOW TEMPS TO CLIMB
QUICKLY INTO THE 80S BY AFTN...WITH THE LOWER SUSQ VALLEY NEARING
90F.
RUC INDICATES STEEPENING MID LEVEL LAPSE RATES ALREADY DEVELOPING
OVER WESTERN PA IN RESPONSE TO STRONG HEATING AND SLOWLY FALLING
MID LEVEL TAMPS AND HEIGHTS. SPC RAP SHOWS CAPES EXCEEDING 200J
OVER WRN PA. MOISTURE CONVERGENCE IS WEAK HOWEVER AND VIZ SHOTS
ARE JUST STARTING TO SHOW THE DEVELOPMENT OF A CU FIELD. BACK OVER
THE LOWER LAKES. THIS SHOULD CONTINUE TO DEVELOP AS THE DAY HEATS
UP...WITH THE BEST CHANCES FOR RAIN BEING OVER MY NWRN COUNTIES.
THE INSTABILITY COMBINED WITH SOME MODEST WIND SHEAR COULD BE
ENOUGH TO SUPPORT ISOLATED STRONG WIND GUSTS IN SOME OF THE
THUNDERSTORMS.
&&
.SHORT TERM /FRIDAY/...
A WEAK HIGH WILL BUILD INTO THE AREA BY LATE FRIDAY AS THE
FRONTAL BOUNDARY LIFTS NORTH AS A WARM FRONT INTO NEW YORK STATE.
SW FLOW AT THE SFC AND ALOFT WILL MAINTAIN VERY WARM AND SOMEWHAT
HUMID CONDITIONS...ESP IN THE SOUTH WHERE TEMPS WILL TOP OUT IN
THE U80S TO LOWER 90S WITH SFC DEWPOINTS IN THE U60S TO AROUND
70F.
HIGH TEMPS IN ALL AREAS FRIDAY WILL ONCE AGAIN BE 10-12F ABOVE
NORMAL.
GFS AND THE NEW NAM KEEP US DRY THRU THE DAY FRIDAY. THIS LOOKS
MORE REASONABLE THAN THE SMALL CHC POPS OF THE 09Z SREF.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
CLOUDS THICKEN UP WITH SHRA/TSRA BECOMING LIKELY WELL AFTER MIDNIGHT
ACROSS THE ALLEGHENY PLATEAU OF NRN AND WRN PENN.
LOW LEVEL WIND SHEAR COULD IMPACT AVIATION AND BE FELT ACRS THE
HIGHER TERRAIN FRIDAY NIGHT INTO SATURDAY...AS THE SSW FLOW IN THE
1-2 KFT AGL LAYER STRENGTHENS TO 35-40 KTS.
DEEP LOW FCST TO DRAG A WARM FRONT...THEN A COLD FRONT ACROSS THE
AREA ON SAT. MODELS DO NOT CLOSE LOW OFF NOW...BUT STILL LOOKS WET.
SOME CHC OF STRONG TO PERHAPS SEVERE STORMS ACROSS THE EAST LATE.
LESS CHC FOR WIDESPREAD HEAVY RAIN NOW...AS SYSTEM DOES NOT CLOSE
OFF AND GO NEGATIVE. STILL WILL BE WET FOR MUCH OF THE DAY.
RATHER STRONG UPPER LVL LOW MOVING ACROSS THE REGION ON SUNDAY...
THUS EXPECT CU TO DEVELOP FAST...LIMIT MAX TEMPS...AND RESULT IN
SHOWERS AND STORMS. DID LOWER TEMPS A TAD FOR SOME PERIODS AFTER
SATURDAY.
WITH THE UPPER LVL LOW MOVING OUT FASTER NOW...SHOULD BE DRY ON
MONDAY.
TUE AND WED LOOK DRY WITH HIGH PRESSURE OVER WV.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
STILL SOME LINGERING CIGS JUST UNDER 3000` OVER SERN PA...BUT ALL
SITES WILL IMPROVE TO VFR BY 18Z.
THE AFTERNOON WILL SEE SCATTERED CONVECTION BECOMING THE THREAT
WITH LOCALIZED RESTRICTIONS IN THE SHOWERS/STORMS AS WELL AS THE
POTENTIAL FOR ISOLATED STRONG WIND GUSTS IN STRONGER
THUNDERSTORMS. MOST LIKLEY AREAS TO SEE THIS SHOULD BE ALONG
NY...PA BORDER.
EXPECT MORE LATE NIGHT FOG AND LOW CLOUDS TONIGHT.
OUTLOOK...
FRI...MAINLY VFR AFTER EARLY MORNING FOG/LOW CLOUD RESTRICTIONS.
SAT...DETERIORATING CONDITIONS WITH THE APPROACH OF A WAVE OF LOW
PRESSURE.
SUN...MVFR EARLY...IMPROVING DURING THE DAY.
MON...NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...LAMBERT/MARTIN
AVIATION...LA CORTE
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
801 AM EDT THU SEP 6 2012
.SYNOPSIS...
A WEAK AREA OF HIGH PRESSURE OVER THE REGION THIS MORNING WILL SLIDE
EAST TO THE SOUTHERN NEW ENGLAND COAST THIS AFTERNOON. A COLD FRONT
WILL MOVE INTO THE AREA TONIGHT AND FRIDAY. AN UPPER TROUGH WILL
FORM OVER THE GREAT LAKES AND MIDWEST DURING THE WEEKEND THEN
AMPLIFY AS IT APPROACHES PENNSYLVANIA...CREATING AN UNSETTLED AND
WET WEATHER PATTERN INTO THE WEEKEND. HIGH PRESSURE WILL BUILD INTO
THE AREA LATE MONDAY...BRINGING IN COOLER TEMPERATURES...BEFORE
MOVING OFF THE COAST LATER IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A WEAK RIDGE OF HIGH PRESSURE /1012MB/ RESIDES OVER THE REGION EARLY
THIS MORNING. MODERATELY STG...MID/UPPER WARM ADVECTION WAS
RESPONSIBLE CREATING AN EXTENSIVE /AND THICK/ SHIELD OF ALTO CU AND
CIRROSTRATUS OVER THE STATE.
THE WESTERN EDGE OF THIS MID AND HIGH CLOUD SHIELD /NEAR THE
OHIO/PENN BORDER AT 09Z/ WILL CONTINUE TO SLIDE TO THE EAST AT
APPROX 20KT...AND REACH A LINE FROM KELM...TO KUNV AND KAOO BY
15-16Z TDY...AND 17-19Z ACROSS THE WEST BRANCH AND MID SUSQ VALLEY.
MIN TEMPS AROUND SUNRISE WILL HAVE QUITE A TIGHT RANGE OF ONLY ABOUT
6-7 DEG F /U50S TO MID 60S/ FROM THE NORMALLY COLDER NW MTNS...TO
THE LOWER SUSQ VALLEY.
THE UPPER SHORTWAVE WITH IT/S PRECEDING WARM ADVECTION ALOFT AND
ITS BKN MID AND HIGH CLOUD DECK WILL BE PASSING EAST OF THE AREA
DURING THE LATE MORNING AND EARLY AFTERNOON HOURS. BEHIND THIS
FEATURE...06Z RUC SUPPORTS A MSUNNY MORNING ACROSS THE WESTERN
MTNS...WITH INCREASING/LESS FILTERED SUNSHINE FOR THE AFTERNOON
ACROSS THE SE HALF OF THE CWA.
THE SUNSHINE AND MDL 8H TEMPS ARND 17C WILL ALLOW TEMPS TO CLIMB
QUICKLY INTO THE 80S BY AFTN...WITH THE LOWER SUSQ VALLEY NEARING
90F.
AFTER AN APPROX 7-8 HOUR PERIOD OF TRANQUIL CONDITIONS FOR THE FIRST
HALF OF THE DAYLIGHT HOURS...CU WILL INCREASE AND GROW VERTICALLY
DURING THE AFTN...AS A POCKET OF STEEP MID LEVEL LAPSE RATES /AROUND
7C PER KM/ OVERSPREADS THE CWA AHEAD OF NEXT SHORTWAVE AND ASSOC
COLD FRONT.
00Z-03Z MDLS/SREF GENERATE A RESPECTABLE AMOUNT OF CAPE BY LATE IN
THE AFTERNOON TODAY. THE BEST CHC OF TSRA WILL BE ACROSS THE NCENT
AND NW MTNS...WHERE LARGE SCALE FORCING AND DECENT UPPER LEVEL
DIVERGENCE...WILL COMBINE WITH MDTLY STG LLVL THETA-E CONVERGENCE
AND MID-LEVEL WESTERLY WINDS.
SFC DEW POINTS MAINLY IN THE LOWER TO MID 60S...WILL HELP TO CREATE
MLCAPES AROUND 1500 J/KG THIS AFTERNOON INTO EARLY THIS EVENING.
THIS INSTABILITY COMBINED WITH THE MODERATE WIND SHEAR COULD BE
ENOUGH TO SUPPORT ISOLD SVR MULTI-CELL TSTORMS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
WEAK LLVL RIDGING MOVES IN FROM THE WEST AS THE BEST UPPER LEVEL
DIVERGENCE WANES/SHIFTS TWD THE MID ATLANTIC COAST. SCATTERED
SHRA/TSRA WILL OCCUR MAINLY BEFORE MIDNIGHT...BUT ISOLATED SHRA/TSRA
WILL STILL BE POSSIBLE LATE AS THE LLVL FRONTAL BOUNDARY STALLS OUT
TEMPORARILY FROM ABOUT KAVP TO KUNV AND KPIT...AND MU/ML CAPES
REMAIN QUITE HIGH GIVEN THE LINGERING POCKET OF STEEP LAPSE RATES
ALOFT AND MOIST BLYR WITH DEWPOINTS IN THE LOWER TO MID 60S ACROSS
THE CENTRAL ZONES...AND PERHAPS AROUND A MUGGY 70F IN THE
SOUTHEAST.
WEAK HIGH BUILDS INTO THE AREA BY LATE FRIDAY AS THE FRONTAL
BOUNDARY LIFTS NORTH AS A WARM FRONT INTO NEW YORK STATE. SW FLOW AT
THE SFC AND ALOFT WILL MAINTAIN VERY WARM AND SOMEWHAT HUMID
CONDITIONS...ESP IN THE SOUTH WHERE TEMPS WILL TOP OUT IN THE U80S
TO LOWER 90S WITH SFC DEWPOINTS IN THE U60S TO AROUND 70F.
HIGH TEMPS IN ALL AREAS FRIDAY WILL ONCE AGAIN BE 10-12F ABOVE
NORMAL.
GRIDDED SKY COVER /CU TOPPED BY PERIODS OF CIRRUS/ WILL AVERAGE
AROUND 50 PERCENT THROUGH THE DAY FRIDAY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
CLOUDS THICKEN UP WITH SHRA/TSRA BECOMING LIKELY WELL AFTER MIDNIGHT
ACROSS THE ALLEGHENY PLATEAU OF NRN AND WRN PENN.
LOW LEVEL WIND SHEAR COULD IMPACT AVIATION AND BE FELT ACRS THE
HIGHER TERRAIN FRIDAY NIGHT INTO SATURDAY...AS THE SSW FLOW IN THE
1-2 KFT AGL LAYER STRENGTHENS TO 35-40 KTS.
DEEP LOW FCST TO DRAG A WARM FRONT...THEN A COLD FRONT ACROSS THE
AREA ON SAT. MODELS DO NOT CLOSE LOW OFF NOW...BUT STILL LOOKS WET.
SOME CHC OF STRONG TO PERHAPS SEVERE STORMS ACROSS THE EAST LATE.
LESS CHC FOR WIDESPREAD HEAVY RAIN NOW...AS SYSTEM DOES NOT CLOSE
OFF AND GO NEGATIVE. STILL WILL BE WET FOR MUCH OF THE DAY.
RATHER STRONG UPPER LVL LOW MOVING ACROSS THE REGION ON SUNDAY...
THUS EXPECT CU TO DEVELOP FAST...LIMIT MAX TEMPS...AND RESULT IN
SHOWERS AND STORMS. DID LOWER TEMPS A TAD FOR SOME PERIODS AFTER
SATURDAY.
WITH THE UPPER LVL LOW MOVING OUT FASTER NOW...SHOULD BE DRY ON
MONDAY.
TUE AND WED LOOK DRY WITH HIGH PRESSURE OVER WV.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
LOW STRATOCU FORMED ONLY IPT AND WILL LIFT BY MID MORNING. THIS
AFTERNOON WILL SEE SCATTERED CONVECTION BECOMING THE THREAT WITH
LOCALIZED RESTRICTIONS IN THE SHOWERS/STORMS AS WELL AS THE
POTENTIAL FOR ISOLATED STRONG WIND GUSTS IN STRONGER
THUNDERSTORMS. AREAS TO RECEIVE THIS SHOULD BE ALONG NY...PA
BORDER. EXPECT ANOTHER ROUND OF FOG/STRATOCU POSSIBLE TONIGHT.
OUTLOOK...
THU...MAINLY VFR AFTER MORNING FOG. SCT SHOWERS/THUNDERSTORMS
DEVELOPING BY AFTERNOON AND LASTING INTO EVENING.
FRI...MAINLY VFR.
SAT...DETERIORATING CONDITIONS WITH THE APPROACH OF A WAVE OF LOW
PRESSURE.
SUN...MVFR EARLY...IMPROVING DURING THE DAY.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...LAMBERT
LONG TERM...LAMBERT/MARTIN
AVIATION...CERU/GARTNER
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
753 AM EDT THU SEP 6 2012
.SYNOPSIS...
A WEAK AREA OF HIGH PRESSURE OVER THE REGION THIS MORNING WILL SLIDE
EAST TO THE SOUTHERN NEW ENGLAND COAST THIS AFTERNOON. A COLD FRONT
WILL MOVE INTO THE AREA TONIGHT AND FRIDAY. AN UPPER TROUGH WILL
FORM OVER THE GREAT LAKES AND MIDWEST DURING THE WEEKEND THEN
AMPLIFY AS IT APPROACHES PENNSYLVANIA...CREATING AN UNSETTLED AND
WET WEATHER PATTERN FOR THE WEEKEND. HIGH PRESSURE WILL BUILD INTO
THE AREA LATE MONDAY...BRINGING IN COOLER TEMPERATURES...BEFORE
MOVING OFF THE COAST LATER IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A WEAK COLD FRONT ENTERING WESTERN PA EARLY TODAY WILL PROVIDE THE
FOCUS FOR SOME SCATTERED CONVECTION LATER TODAY. IN THE MEANTIME A
WEAK UPPER TROF IS BRINGING A FEW SPRINKLES TO MY SERN ZONES AND
WILL CONTINUE OFF TO THE EAST BY MID TO LATE MORNING. BEHIND THIS
FEATURE...THE RUC SUPPORTS A MSUNNY MORNING ACROSS THE WESTERN
MTNS...WITH INCREASING SUNSHINE FOR LATER IN THE MORNING AND
AFTERNOON ACROSS THE SE HALF OF THE CWA.
THE SUNSHINE AND MDL 8H TEMPS ARND 17C WILL ALLOW TEMPS TO CLIMB
QUICKLY INTO THE 80S BY AFTN...WITH THE LOWER SUSQ VALLEY NEARING
90F.
AFTER AN APPROX 7-8 HOUR PERIOD OF TRANQUIL CONDITIONS FOR THE FIRST
HALF OF THE DAY...CU WILL INCREASE AND GROW AS A POCKET OF
STEEPENING LAPSE RATES...AS MUCH AS 7C/KM...OVERSPREADS THE CWA
AHEAD OF NEXT SHORTWAVE.
SFC DEW POINTS MAINLY IN THE LOWER TO MID 60S...WILL HELP TO
CREATE MLCAPES AROUND 1500 J/KG THIS AFTERNOON INTO EARLY THIS
EVENING. THIS INSTABILITY COMBINED WITH THE MODERATE WIND SHEAR
COULD BE ENOUGH TO SUPPORT ISOLD SVR MULTI-CELL TSTORMS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
WEAK LLVL RIDGING MOVES IN FROM THE WEST AS THE BEST UPPER LEVEL
DIVERGENCE WANES/SHIFTS TWD THE MID ATLANTIC COAST. SCATTERED
SHRA/TSRA WILL OCCUR MAINLY BEFORE MIDNIGHT...BUT ISOLATED SHRA/TSRA
WILL STILL BE POSSIBLE LATE AS THE LLVL FRONTAL BOUNDARY STALLS OUT
TEMPORARILY FROM ABOUT KAVP TO KUNV AND KPIT...AND MU/ML CAPES
REMAIN QUITE HIGH GIVEN THE LINGERING POCKET OF STEEP LAPSE RATES
ALOFT AND MOIST BLYR WITH DEWPOINTS IN THE LOWER TO MID 60S ACROSS
THE CENTRAL ZONES...AND PERHAPS AROUND A MUGGY 70F IN THE
SOUTHEAST.
WEAK HIGH BUILDS INTO THE AREA BY LATE FRIDAY AS THE FRONTAL
BOUNDARY LIFTS NORTH AS A WARM FRONT INTO NEW YORK STATE. SW FLOW AT
THE SFC AND ALOFT WILL MAINTAIN VERY WARM AND SOMEWHAT HUMID
CONDITIONS...ESP IN THE SOUTH WHERE TEMPS WILL TOP OUT IN THE U80S
TO LOWER 90S WITH SFC DEWPOINTS IN THE U60S TO AROUND 70F.
HIGH TEMPS IN ALL AREAS FRIDAY WILL ONCE AGAIN BE 10-12F ABOVE
NORMAL.
GRIDDED SKY COVER /CU TOPPED BY PERIODS OF CIRRUS/ WILL AVERAGE
AROUND 50 PERCENT THROUGH THE DAY FRIDAY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
CLOUDS THICKEN UP WITH SHRA/TSRA BECOMING LIKELY WELL AFTER MIDNIGHT
ACROSS THE ALLEGHENY PLATEAU OF NRN AND WRN PENN.
LOW LEVEL WIND SHEAR COULD IMPACT AVIATION AND BE FELT ACRS THE
HIGHER TERRAIN FRIDAY NIGHT INTO SATURDAY...AS THE SSW FLOW IN THE
1-2 KFT AGL LAYER STRENGTHENS TO 35-40 KTS.
DEEP LOW FCST TO DRAG A WARM FRONT...THEN A COLD FRONT ACROSS THE
AREA ON SAT. MODELS DO NOT CLOSE LOW OFF NOW...BUT STILL LOOKS WET.
SOME CHC OF STRONG TO PERHAPS SEVERE STORMS ACROSS THE EAST LATE.
LESS CHC FOR WIDESPREAD HEAVY RAIN NOW...AS SYSTEM DOES NOT CLOSE
OFF AND GO NEGATIVE. STILL WILL BE WET FOR MUCH OF THE DAY.
RATHER STRONG UPPER LVL LOW MOVING ACROSS THE REGION ON SUNDAY...
THUS EXPECT CU TO DEVELOP FAST...LIMIT MAX TEMPS...AND RESULT IN
SHOWERS AND STORMS. DID LOWER TEMPS A TAD FOR SOME PERIODS AFTER
SATURDAY.
WITH THE UPPER LVL LOW MOVING OUT FASTER NOW...SHOULD BE DRY ON
MONDAY.
TUE AND WED LOOK DRY WITH HIGH PRESSURE OVER WV.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
CURRENT SATELLITE HAS WIDESPREAD MIDDLE TO HIGH CLOUDS MOVING OVER
THE STATE. THIS WILL REDUCE THE PROBABILITIES FOR FOG OVERNIGHT AND
THIS MORNING. CURRENT DEW POINT DEPRESSIONS ARE IN THE SINGLE
DIGITS...WHICH IS A GOOD SIDE FOR FOG. WITH THE CALM WINDS ACROSS
THE BOARD AND AN INVERSION IN PLACE...PATCHY FOG IS CERTAINLY
PROBABLY THROUGH ANY MID TO HIGH CLOUDS WILL REDUCE ITS INTENSITY.
SO EXPECT TO SEE THE DEVELOPMENT OF SOME VALLEY FOG BY 2-4 AM AND
CONTINUE A FEW HOURS AFTER SUNRISE. VIZ WILL BE THE PRIMARY
RESTRICTIONS UNTIL CONDITIONS LIFT...IN THE 1-3 MILE
RANGE...THOUGH UNV COULD SEE IFR OR LOWER CIGS. CONDITIONS WILL
CONTINUE UNTIL MID TO LATE MORNING.
THURS AFTERNOON WILL SEE SCATTERED CONVECTION BECOMING THE THREAT
WITH LOCALIZED RESTRICTIONS IN THE SHOWERS/STORMS AS WELL AS THE
POTENTIAL FOR ISOLATED STRONG WIND GUSTS IN STRONGER
THUNDERSTORMS.
OUTLOOK...
THU...MAINLY VFR AFTER MORNING FOG. SCT SHOWERS/THUNDERSTORMS
DEVELOPING BY AFTERNOON AND LASTING INTO EVENING.
FRI...MAINLY VFR.
SAT...DETERIORATING CONDITIONS WITH THE APPROACH OF A WAVE OF LOW
PRESSURE.
SUN...MVFR EARLY...IMPROVING DURING THE DAY.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE/LAMBERT
NEAR TERM...LA CORTE/LAMBERT
SHORT TERM...LAMBERT
LONG TERM...LAMBERT/MARTIN
AVIATION...CERU/GARTNER
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1033 AM EDT THU SEP 6 2012
.SYNOPSIS...
A WEAK FRONTAL BOUNDARY WILL DRIFT ACROSS THE REGION TODAY FOLLOWED
BY SLIGHTLY DRIER AIR FOR FRIDAY. A STRONG COLD FRONT WILL MOVE
ACROSS THE AREA SATURDAY AND SATURDAY NIGHT WITH DRY AIR
OVERSPREADING THE REGION ON SUNDAY. DRY HIGH PRESSURE WILL SETTLE
OVER THE REGION EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM EDT...THE LATEST RAP MATCHES WELL WITH THE WATER VAPOR
IMAGERY DEPICTION OF A SHORT WAVE ALONG THE NC/TN LINE. THIS FEATURE
WILL GRADUALLY MOVE EAST THROUGH THE DAY. THE NAM CURRENTLY HAS TOO
MUCH CONVECTION OVER THE WRN PART OF THE FA WITH THIS FEATURE AS
DOES THE RAP. THERE IS QUITE A BIT OF LOW CLOUD COVER ACROSS THE
FOOTHILLS AND PIEDMONT ATTM WHICH IS CUTTING OFF SFC HEATING. THIS
WILL RESULT IN CONTINUED SUPPRESSION OF CONVECTION INTO THE EARLY
AFTN. THEREAFTER...THE MODEL SOLUTIONS OF SCT CONVECTION DEVELOPING
OVER THE FOOTHILLS OR WESTERN PIEDMONT BY EARLY AFTN AND THEN
TRACKING EAST OF FA BY EARLY EVENING STILL LOOKS GOOD.
TO ACCOUNT FOR THESE TRENDS I/VE CUT BACK POPS THROUGH 17 UTC.
THEREAFTER I HAVE MUCH THE SAME WEATHER AND POP GRIDS THAT THE MID
SHIFT HAD.
AS OF 700 AM EDT...THE MID AND HIGH CLOUDS OVER THE REGION AHEAD OF
AN APPROACHING H5 SHORTWAVE HAVE THINNED A BIT...BUT THIS HAS
PERMITTED LOW STRATUS TO BECOME A BIT MORE WIDESPREAD...SO THERE IS
NO NET CHANGE IN THE SKY COVER. SHOWER COVERAGE IS SLOWLY RAMPING UP
OVER THE MTNS AS UPPER DPVA STARTS TO MOVE IN. THE MOST POTENT VORT
MAX IN THE UPSTREAM SHORTWAVE TROUGH SHOULD CROSS THE SRN
APPALACHIANS MAINLY THIS MORNING AND THEN MOVE OUT OVER THE PIEDMONT
THROUGH THE AFTN OR EARLY EVENING HOURS. WESTERLY DOWNSLOPING FLOW
AT LOW LEVELS MAY INITIALLY KEEP PRECIPITATION COVERAGE LOW EAST OF
THE MTNS THIS MORNING...BUT THE PASSING UPPER SUPPORT ALONG WITH
DEVELOPING LEE TROUGHING NEAR THE SURFACE SHOULD PROVIDE ENOUGH LIFT
FOR SCATTERED CONVECTION THIS AFTN. IN ADDITION TO THE
DOWNSLOPE...GRADUAL MID AND UPPER LEVEL DRYING IN THE SOUNDINGS
COULD LIMIT POPS SOMEWHAT. WILL THUS HEDGE TOWARD THE DRIER GFS
BASED MOS FOR POPS THIS AFTN. THE MID LEVEL DRYING...HOWEVER...COULD
INCREASE THE MICROBURST THREAT WITH ANY TSTMS THAT DO MANAGE TO
DEVELOP OVER THE PIEDMONT. IN ADDITION...MAX TEMPERATURES SHOULD BE
A COUPLE OF DEGREES WARMER THAN WED AFTN MOST AREAS. THIS WILL ADD
TO THE PIEDMONT INSTABILITY WHERE SFC DEWPOINTS SHOULD LINGER AROUND
70 DEGREES THROUGH LATE DAY.
STRONGER DRYING FROM THE TOP DOWN IS EXPECTED TONIGHT AS FLOW TURNS
NW TO N THROUGH A DEEP LAYER. THE BOUNDARY LAYER...HOWEVER...SHOULD
REMAIN FAIRLY MOIST TO CREATE THE POTENTIAL FOR FOG/VSBY PROBLEMS
OVERNIGHT. MIN TEMPS WILL LIKELY BE A CATEGORY COOLER THAN IN RECENT
DAYS.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
AS OF 245 AM THURSDAY...THE ATMOSPHERE IS PROGGED TO DRY OUT
CONSIDERABLY ON FRIDAY...WITH FORECAST SOUNDING PWATS DECREASING TO
AROUND ONE INCH BY AFTERNOON. MEANWHILE...A LOW AMPLITUDE UPPER
RIDGE AXIS WILL NOSE INTO THE REGION FROM THE SOUTHWEST. THESE
FACTORS WILL RESULT IN ONE OF THE LOWEST POP DAYS WE/VE SEEN IN SOME
TIME. NEVERTHELESS...STRONG INSOLATION (MAX TEMPS AROUND 90 EXPECTED
IN THE PIEDMONT) WILL ALLOW FOR MODERATE DESTABILIZATION...WHICH
SHOULD SUPPORT SOME HIGH TERRAIN CONVECTION BY LATE AFTERNOON.
FORECAST SOUNDINGS DEPICT A WEAK MID-LEVEL SUBSIDENCE INVERSION IN
THE PIEDMONT...SO IT IS UNCERTAIN AS TO HOW FAR INTO THE FOOTHILLS/
PIEDMONT THE ATMOSPHERE WILL BE ABLE TO SUSTAIN CONVECTION. SLIGHT
CHANCE POPS WERE INHERITED OUTSIDE THE MTNS...AND THIS STILL SEEMS
REASONABLE.
CONVECTION SHOULD DISSIPATE FATHER QUICKLY FRIDAY EVENING.
HOWEVER...STRONG HEIGHT FALLS WILL BE OCCURRING DURING THIS TIME
WEST THROUGH NORTHWEST OF THE AREA...DRIVING A STRONG COLD FRONT
TOWARD THE APPALACHIANS FRIDAY NIGHT. THERE ARE SLIGHT TIMING
DIFFERENCES IN THE OPERATIONAL MODELS...WITH THE NAM BEING ABOUT 3
HOURS FASTER THAN THE GFS. WE HAVE FAVORED THE SLIGHTLY FASTER
NAM...AS THERE WILL PROBABLY BE A MAJOR CONVECTIVE/COLD POOL
COMPONENT TO THE FRONTAL BAND...WHICH ALWAYS SEEMS TO RESULT IN
FASTER TIMING THAN DEPICTED BY THE MODELS. SPEAKING OF WHICH...
SATURDAY COULD BE AN INTERESTING CONVECTIVE DAY FOR OUR AREA...AS
THE COLD FRONT SEEMS DESTINED TO SWEEP ACROSS THE PIEDMONT DURING
PEAK HEATING TIME. THERE MAY BE EXTENSIVE MORNING HIGH CLOUDS AND
MID-LEVEL LAPSE RATES WILL BE WEAK...WHICH WOULD LIKELY LIMIT CAPE
VALUES TO WELL UNDER 2000 J/KG. NEVERTHELESS...IT APPEARS SHEAR WILL
BE FAIRLY STRONG...PARTICULARLY IN THE LOWER LEVELS...SO THERE IS A
LOW-END ORGANIZED SEVERE WEATHER THREAT.
CHANCE POPS WILL BEGIN OVER THE SOUTHWEST NC MTNS LATE FRIDAY
NIGHT...INCREASING TO LIKELY ACROSS THE MTNS BY EARLY AFTERNOON...
WITH HIGH CHANCES EXTENDING TO THE EAST DURING MID/LATE AFTERNOON.
THE MODEL CONSENSUS IS TO SWEEP ALL CONVECTION EAST OF THE AREA BY
00Z SUNDAY...SO POPS HAVE BEEN ADJUSTED DOWN SAT NIGHT THROUGH EARLY
SUNDAY. (SLIGHT/LOW CHANCES AT 00Z...DIMINISHING TO LESS THAN 20
PERCENT BY 12Z). COOL ADVECTION FLOW WILL RESULT IN MIN TEMPS ABOUT
A CAT BELOW NORMAL SUNDAY MORNING.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
AS OF 130 AM EDT THURSDAY...L/WV TROUGH AXIS WITH DRY AND COOLER
NORTHERLY LLVL FLOW IS PROGGED TO BE ATOP THE REGION ON MONDAY.
TEMPERATURES WILL START OFF THE PERIOD 2-3 CATEGORIES BELOW CLIMO.
SFC RIDGE AXIS WILL BUILD IN ON TUESDAY AS UPPER TROUGH AXIS
PROGRESSES OFFSHORE AND GIVES WAY TO NW FLOW ALOFT. CONTINUED DRY
CONDITIONS ARE EXPECTED WITH TEMPERATURES NEAR PERSISTENCE. DEEP
LAYERED RIDGING WILL THEN DEVELOP ACRS THE SE CONUS BY THE END OF THE
PERIOD AND MAX TEMPERATURES ON WEDNESDAY WILL MODERATE A FEW DEG F
BUT STILL AVERAGE BELOW NORMAL.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
AT KCLT...THE LOW CLOUD IR SATELLITE PRODUCT SHOWS IFR CIGS KNOCKING
ON THE DOOR AT CLT. WILL NEED TO CARRY TEMPO IFR FOR AT LEAST AN
HOUR. THERE IS NOT TOO MUCH MID OR HIGH CLOUD AT PRESENT ABOVE THE
PIEDMONT STRATUS LAYER...SO IT SHOULD BURN OFF FAIRLY QUICKLY.
ATTENTION WILL THEN TURN TO THE PASSING WEAK SHORTWAVE...WITH BETTER
FORCING FOR SHRA OR TSRA AFTER 18Z. WINDS WILL STAY SW TODAY WITH
LEE TROUGHING...BUT LIKELY TURN WNW THIS EVENING. SOME DRYING IS
INDICATED TONIGHT...BUT LINGERING BL MOISTURE COULD CREATE FOG/LOW
CLOUD PROBLEMS TOWARD DAYBREAK FRI.
ELSEWHERE...AN IFR STRATUS LAYER HAS DEVELOPED THIS MORNING AS MID
AND HIGH CLOUDS THINNED OUT OVERNIGHT. THIS SHOULD BURN OFF FAIRLY
QUICKLY...WITH MAINLY VFR CUMULUS FILLING IN WITH HEATING OF THE
MOIST BOUNDARY LAYER. WILL START OFF WITH VCSH AT KAVL AND KHKY
FIRST...AND THEN INTRODUCE VCTS FOR MAINLY THE AFTERNOON
HOURS...WITH THE MOVING WINDOW FROM WEST TO EAST. ANY FURTHER
RESTRICTIONS WOULD BE DUE TO CONVECTIVE SHOWERS AND THESE SHOULD BE
SCATTERED AT BEST. SW WINDS AHEAD OF THE LEE TROUGH TODAY WILL TURN
NW OVERNIGHT...EXCEPT FOR WINDS REMAINING NW AT KAVL THROUGH THE
PERIOD. PROFILES WILL DRY OUT FROM THE TOP DOWN TONIGHT...BUT
LINGERING BL MOISTURE COULD CREATE FOG/VSBY PROBLEMS OVERNIGHT. WILL
ONLY FEATURE IFR FOG AT KAVL...WITH MVFR FOG AT KHKY AND KAND...AS A
STARTING POINT.
OUTLOOK...BRIEF DRYING FROM THE WEST IS EXPECTED INTO FRIDAY. A COLD
FRONT WILL APPROACH THE REGION FROM THE NORTHWEST ON SATURDAY AND
MOVE EAST OF THE AREA ON SUNDAY. DRY HIGH PRES WILL DOMINATE THE
AREA EARLY NEXT WEEK.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...CSH
NEAR TERM...MCAVOY
SHORT TERM...JDL
LONG TERM...CSH
AVIATION...HG
AREA FORECAST DISCUSSION
NWS TUCSON AZ
910 AM MST THU SEP 6 2012
.SYNOPSIS...ABUNDANT MOISTURE WILL RESULT IN SCATTERED THUNDERSTORMS
INTO EARLY NEXT WEEK. EXPECT LOCALLY HEAVY RAINFALL WITH THE
STRONGER THUNDERSTORMS. DAYTIME TEMPERATURES WILL GENERALLY BE A FEW
DEGREES BELOW NORMAL.
&&
.DISCUSSION...MOSTLY CLEAR SKIES TO PARTLY CLOUDY SKIES ACROSS SE AZ
AT THIS TIME. DEWPOINTS VALID 16Z RANGED FROM THE 60S-LOWER 70S F...
AND THESE TEMPS WERE NEARLY IDENTICAL TO 24 HOURS AGO. 06/12Z KTWC
SOUNDING TOTAL PRECIP WATER WAS NEAR 1.75 INCHES. BLENDED TOTAL
PRECIP WATER IMAGERY DEPICTED VALUES RANGING FROM 1.50 INCHES NEAR
THE NEW MEXICO BORDER TO 1.85 INCHES ACROSS WRN PIMA COUNTY.
WATER VAPOR IMAGERY INDICATES CYCLONIC CIRCULATION FEATURE MOVING
NEWD ACROSS NERN SONORA. 06/06Z UNIV OF AZ WRF-GFS...06/12Z UNIV OF
AZ WRF-NAM AND 06/11Z RUC HRRR WERE VERY SIMILAR WITH DEPICTING AN
ACTIVE CONVECTIVE PERIOD ACROSS SE AZ FROM THIS AFTERNOON THRU FRI.
INHERITED POPS FOR THIS AFTERNOON AND THIS EVENING SEEM REASONABLE
AS THE AFOREMENTIONED SYNOPTIC-SCALE SYSTEM APPROACHES SE AZ. MAY
STILL ADJUST POPS UPWARD ABOUT 10-20 PERCENT LATER THIS MORNING
AFTER RECEIPT OF THE 06/12Z GFS. THE MAIN THREAT WILL BE LOCALLY
HEAVY RAINFALL AS WELL AS STRONG WIND GUSTS. THE BULK OF CONVECTIVE
ACTIVITY IS EXPECTED TO END LATE TONIGHT.
&&
.PREV DISCUSSION...SCATTERED TYPE POPS EXPECTED AGAIN DURING THE DAY
ON FRIDAY AND ON SATURDAY AS WELL...AS THE REMNANTS OF THE
DISTURBANCE RESIDE OVER SOUTHERN ARIZONA ON FRIDAY AND MOVES TOWARD
SOUTHWEST ARIZONA ON SATURDAY.
THE DISTURBANCE WILL RESIDE OVER SOUTHERN CALIFORNIA OR THE COLORADO
RIVER BASIN ON SUNDAY WITH A RIDGE OF HIGH PRESSURE TO OUR EAST OVER
NEW MEXICO. THIS WILL ALLOW SOUTHERLY FLOW TO CONTINUE TO PUMP
MOISTURE NORTHWARD. THIS PATTERN WILL LIKELY CONTINUE TO PERSISTS
THROUGH EARLY NEXT WEEK FOR ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS EACH AFTERNOON AND EVENING DURING THAT TIME. BY MID
WEEK OR SO...HIGH PRESSURE WILL BUILD FROM THE WEST FOR A
POSSIBILITY THAT SOME DRY AIR MAY INTRUDE FROM THE WEST FOR A
DECREASE IN RAIN CHANCES...BUT ISOLATED IN NATURE.
HIGH TEMPERATURES GENERALLY 2 TO 4 DEGS BELOW NORMAL TODAY THROUGH
SATURDAY...THEN AT OR SLIGHTLY BELOW NORMAL FOR THE REMAINDER OF THE
FORECAST PERIOD. LOWS AROUND 2 TO 4 DEGS ABOVE NORMAL EACH MORNING.
&&
.AVIATION...SCT TO NUMEROUS TSRA/SHRA AFTER 18Z AND CONTINUING INTO
THIS EVENING. WIND GUSTS AROUND 40-45 KTS AND MVFR CIGS/VSBYS WITH
THE STRONGEST TSRA. ISOLD-SCT -TSRA/-SHRA 06Z-12Z FRIDAY.
OTHERWISE...VFR CONDITIONS AND SURFACE WIND MOSTLY LESS THAN 10 KTS
THRU EARLY FRIDAY MORNING OR 07/12Z. AVIATION DISCUSSION NOT UPDATED
FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...THERE IS A CHANCE OF THUNDERSTORMS MAINLY DURING THE
AFTERNOON AND EVENING HOURS INTO EARLY NEXT WEEK. EXPECT A GRADUAL
DECREASE IN THUNDERSTORM ACTIVITY BY THE MIDDLE OF NEXT WEEK.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/TUCSON
BF
PREV DISCUSSION...MOLLERE
AREA FORECAST DISCUSSION
NWS ALBANY NY
511 PM EDT THU SEP 6 2012
.SYNOPSIS...
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL
PERSIST ACROSS PORTIONS OF THE REGION THIS EVENING...AS ANOTHER WEAK
FRONTAL BOUNDARY CROSSES THE AREA. THE FRONT WILL THEN STALL SOUTH
AND EAST OF THE REGION FRIDAY...BEFORE A STRONGER FRONT APPROACHES
FROM THE WEST LATE SATURDAY BRINGING THE POTENTIAL FOR MORE
WIDESPREAD SHOWERS AND THUNDERSTORMS. MUCH COOLER AIR WILL FILTER
INTO THE REGION IN THE WAKE OF THIS FRONT FOR SUNDAY INTO EARLY NEXT
WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 5 PM EDT...ISOLATED THUNDERSTORMS HAVE AFFECTED PORTIONS OF
THE SOUTHERN ADIRONDACKS...AND HAVE APPROACHED...BUT WEAKENED
BEFORE REACHING THE SCHOHARIE VALLEY. IT APPEARS THAT THE
COMBINATION OF LIMITED HEATING DUE TO PERSISTENT HIGH
CLOUDINESS...AS WELL AS THE FACT THAT MUCH OF OUR REGION WAS
LOCATED WITHIN THE UNFAVORABLE REGION OF A COUPLED JET STRUCTURE
FOR UPWARD MOTION /WITHIN THE RIGHT EXIT REGION OF THE JET MAX
TRANSLATING ACROSS THE EASTERN GREAT LAKES AND WITHIN RIGHT
ENTRANCE REGION OF JET MAX TRANSLATING ACROSS WESTERN NEW ENGLAND
ACCORDING TO THE RUC13 AND GFS-40 300-200 MB WIND ISOTACHS/ HAS
WORKED TO GREATLY SUPPRESS CONVECTION IN OUR REGION. THIS COUPLED
JET STRUCTURE OF THE UNFAVORABLE KIND FOR UPWARD MOTION AND
CONVECTION SHOULD ALSO TRANSLATE FURTHER N AND E OF THE REGION
THIS EVENING...SO CAN NOT COMPLETELY RULE OUT ADDITIONAL ISOLATED
TO PERHAPS SCATTERED CONVECTION DURING THE EVENING...MAINLY ACROSS
NORTHERN AREAS...AND PERHAPS THE EASTERN CATSKILLS AS DOWNWARD
MOTION DECREASES.
THE SURFACE BOUNDARY PARTIALLY RESPONSIBLE FOR TRIGGERING THIS
CONVECTION WILL PASS ACROSS THE REGION LATER THIS EVENING...BEFORE
SLOWING DOWN ACROSS SOUTHERN PORTIONS OF THE REGION LATER TONIGHT.
FOR NOW...WILL TAPER POPS AFTER MIDNIGHT...FROM NW TO SE.
HOWEVER...BOTH THE 12Z NAM AND CMC INDICATE SOME ADDITIONAL
CONVECTIVE POTENTIAL REDEVELOPING BEFORE DAYBREAK ACROSS SOUTHERN
PORTIONS OF THE REGION. FOR NOW...HAVE NOT INCLUDED POPS...BUT
WILL NEED TO WATCH RADAR TRENDS OVERNIGHT AS THIS POSSIBILITY CAN
NOT COMPLETELY BE RULED OUT.
ALTHOUGH THE BOUNDARY LAYER MIXED SIGNIFICANTLY BETTER THAN ON
WED...DECREASING WINDS...AND CLEARING SKIES MAY ALLOW FOR PATCHY
FOG TO DEVELOP AGAIN LATER TONIGHT...ESP IN RIVER VALLEYS...AND
HAVE INCLUDED MENTION IN FORECAST. ASSUMING LITTLE OR NO RAIN
OCCURS...THE EXTENT OF THE FOG AND/OR LOW CLOUDS SHOULD BE LESS
THAN THIS MORNING.
FOR MINS...HAVE SIDED A BIT CLOSER TO THE WARMER MET MOS...WITH
MID 50S TO LOWER 60S IN MOST AREAS...EXCEPT FOR 45-50 ACROSS THE
SOUTHERN ADIRONDACKS.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/...
FRIDAY...THE WEAK BOUNDARY ACROSS SOUTHERN AREAS SHOULD BEGIN
DRIFTING BACK NORTH DURING THE AFTERNOON AND EVENING HOURS. THIS
MAY BE JUST ENOUGH OF A LOW LEVEL TRIGGER TO ALLOW FOR ISOLATED
THUNDERSTORMS TO DEVELOP IN THE AFTERNOON...ESP ACROSS HIGHER
TERRAIN...WHERE SLIGHT CHC POPS ARE INDICATED. HAVE KEPT MOST
AREAS FROM THE CAPITAL REGION N AND W OF ALBANY GENERALLY
DRY. FOR MAX TEMPS...GENERALLY FOLLOWED WITH BLEND OF MAV/MET
MOS...WITH LOWER/MID 80S IN MOST VALLEYS...AND 75-80 ACROSS HIGHER
TERRAIN. DEWPOINTS SHOULD GRADUALLY RISE INTO AND THROUGH THE
LOWER/MID 60S FOR AREAS NEAR AND SOUTH OF THE MOHAWK RIVER BY LATE
IN THE DAY...MAKING FOR MORE HUMID CONDITIONS TO DEVELOP ONCE AGAIN.
FRI NT...INCREASING SOUTH/SOUTHEAST FLOW WILL DEVELOP ACROSS THE
REGION...AND MAY BECOME ENHANCED UP THE HUDSON RIVER VALLEY
BENEATH DEVELOPING INVERSION. SO...EXPECT A BREEZY AND WARM
NIGHT...WITH MINS ONLY FALLING INTO THE 60S IN MOST AREAS...EXCEPT
POSSIBLY SOME 50S ACROSS THE SOUTHERN ADIRONDACKS. MODELS SUGGEST
A LOW LEVEL JET SEGMENT TRANSLATING NNE ACROSS THE SOUTHERN
ADIRONDACKS LATE AT NIGHT...WITH ENHANCED LOW LEVEL CONVERGENCE
ALONG ITS LEADING EDGE. THIS MAY CONTRIBUTE TO INCREASED CHANCES
FOR SHOWERS/TSTMS LATE ACROSS THE WESTERN ADIRONDACKS AND POSSIBLY
MOHAWK VALLEY.
SAT-SAT NT...GUSTY SOUTH WINDS ARE EXPECTED TO DEVELOP AHEAD OF AN
APPROACHING COLD FRONT FROM THE WEST. THIS FRONT IS EXPECTED
SLOWLY APPROACH FROM THE WEST LATE IN THE DAY...ALTHOUGH
DETERMINISTIC MODELS HAVE SLIGHT TIMING DIFFERENCES...WITH
POSSIBLE WEAK WAVES DEVELOPING ALONG THE BOUNDARY. MODELS ALSO
SUGGEST THAT UPPER LEVEL SYSTEM TAKES ON MORE OF A NEGATIVE
TILT...AS ADDITIONAL SHORTWAVE ENERGY DIVES SOUTH FROM CANADA INTO
THE UPPER OHIO VALLEY REGION. THIS SUGGESTS THE POSSIBILITY OF A
NARROW COLD FRONTAL RAINBAND ACCOMPANYING/PRECEDING THE
FRONT...WHICH MAY BE ACCOMPANIED BY A BRIEF PERIOD OF VERY HEAVY
RAIN...AND GUSTY WINDS. ALSO...GIVEN A STRONG LOW LEVEL WIND FIELD
DEVELOPING AHEAD OF THE BOUNDARY...WILL NEED TO WATCH FOR ANY
DISCRETE THUNDERSTORMS THAT DEVELOP AHEAD OF THE FRONTAL
BOUNDARY...AS LOW LEVEL SHEAR WILL BE RATHER HIGH. THE QUESTION AS
TO WHETHER HOW MANY DISCRETE CELLS CAN DEVELOP WILL BE EXTENT OF
PREFRONTAL CLOUD COVER...AS LOW CLOUDS MAY DEVELOP AND MOVE NORTH
WITHIN STRONG SOUTH WIND FLOW. SHOULD LESS CLOUDS/MORE SUN
DEVELOP...AN ENHANCED THREAT FOR STRONG THUNDERSTORMS WILL EXIST.
EXPECT MAX TEMPS TO REACH 80-85 IN VALLEYS...AND 75-80 ACROSS
HIGHER ELEVATIONS. SHOWERS/TSTMS WILL EVENTUALLY DECREASE FROM W
TO E LATER SAT NT AS THE FRONT MOVES E OF THE REGION.
AGAIN...TIMING DIFFS EXIST ON HOW FAST THIS OCCURS...WITH THE BEST
CHANCE FOR RAIN MAINLY THROUGH MIDNIGHT.
SUNDAY-SUNDAY NIGHT...IN THE WAKE OF THE FRONT...MUCH COOLER AIR
WILL FILTER INTO THE REGION ON BRISK WEST WINDS. THE COMBINATION
OF CHILLY AIR PASSING OVER THE MUCH WARMER GREAT LAKES SHOULD LEAD
TO ENHANCED CLOUDS...AND SHOWER POTENTIAL FOR AREAS N AND W OF
ALBANY. IN ADDITION...FORCING FROM A STRONG SHORTWAVE APPROACHING
FROM THE SOUTHWEST MAY FURTHER CONTRIBUTE TO SHOWER DEVELOPMENT
DURING THE DAY...SO WILL KEEP SLIGHT CHC TO LOW CHC POPS THROUGH
SUNDAY EVENING...TAPERING SUN NT. SUNDAY MAXES WILL GENERALLY
REACH 70-75 IN VALLEYS...AND 50S TO LOWER 60S ACROSS HIGHER
TERRAIN ACROSS THE SOUTHERN ADIRONDACKS...AND 65-70 IN WESTERN NEW
ENGLAND. MINS FOR SUN NT SHOULD FALL INTO THE 40S AND LOWER 50S.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
A RATHER TRANQUIL PERIOD OF WEATHER IS EXPECTED ACROSS THE REGION AS
WE WATCH A DEPARTING UPPER TROUGH TO BE REPLACED BY RIDGING AND
RISING SURFACE PRESSURES THROUGH THE MID WEEK PERIOD. TO ACCOUNT
FOR THE RESIDUAL CYCLONIC FLOW ON MONDAY...WE WILL HOLD ONTO THE
SLIGHT CHANCE POPS ACROSS THE DACKS. OTHERWISE...UNSEASONABLY
COOLER WEATHER TO START THE WEEK AS SINGLE DIGIT 850MB TEMPS WILL
LIKELY HOLD HIGHS INTO THE 60S TO NEAR 70F FOR VALLEY LOCATIONS ON
MONDAY...THEN A GRADUAL WARMING OF THE COLUMN THROUGH THE MID WEEK
PERIOD UNDER A GOOD DEAL OF SUNSHINE WITH HIGHS WELL INTO THE 70S TO
NEAR 80F FOR VALLEY LOCATIONS WEDNESDAY. OVERNIGHT LOWS WILL BE
COOLEST MONDAY NIGHT INTO TUESDAY NIGHT WITH MOSTLY 40S TO NEAR 50F
WITH A GRADUAL WARMING EXPECTED INTO THE MID WEEK PERIOD.
&&
.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
VFR CONDITIONS ARE EXPECTED FOR THE MAJORITY OF THE AFTERNOON AND
EARLY EVENING HOURS. WE CONTINUE TO WATCH AN INCREASING AREA OF
ENHANCED CU ACROSS THE HIGHER TERRAIN OF THE DACKS THAT MIGHT BE THE
BEGINNING STAGES FOR SHOWERS/THUNDERSTORMS. LATEST EXPERIMENTAL
REFLECTIVITIES POINT TOWARD A SCT-BKN LINE OF CONVECTION TO MOVE
INTO THE HUDSON RIVER VALLEY AND WESTERN NEW ENGLAND TOWARD 20Z. WE
WILL PLACE A VCSH AT THIS TIME FOR TAF SITES AND MONITOR/AMEND ONCE
TRENDS HAVE BEEN IDENTIFIED.
ANY CONVECTION SHOULD QUICKLY DISSIPATE THIS EVENING WITH THE
COMBINATION OF THE LOSS OF DAYTIME HEATING AND FRONTAL PASSAGE.
HOWEVER...THIS FRONT BECOMES QUITE DIFFUSE AS IT TRACKS INTO THE
CATSKILLS AND MID HUDSON VALLEY INCLUDING NW CT. MODELS ARE IN
AGREEMENT WITH SOME ENHANCED CU DEVELOPING THAT MAY IMPACT SOUTHERN
LOCATIONS OVERNIGHT. THIS WILL PLAY HAVOC WITH FOG POTENTIAL AND
IMPACTS. FOR NOW...GIVEN CROSS OVER TEMPERATURES ARE AT LEAST
EXPECTED...WE WILL DROP INTO MVFR FOR VIS AND FAVORED LOCATIONS LIKE
KGFL-KPOU INTO IFR THRESHOLDS. THIS LOW STRATUS MAY ALSO IMPACT
KPSF AS WE WILL ALSO INCLUDE IFR CONDITIONS OVERNIGHT.
WINDS WILL BE RATHER LIGHT AND VARIABLE THROUGH THE PERIOD...WITH
MAIN WIND DIRECTION FROM THE SOUTH-SOUTHWEST THROUGH THE PERIOD.
OUTLOOK...
FRI...MAINLY VFR. MVFR/IFR POSSIBLE DUE TO FOG/BR ESPECIALLY AT
KGFL AND KPSF AT NIGHT/EARLY IN THE MORNING.
SAT...RAIN BECOMING LIKELY WITH A CHC OF TSTMS.
SUN...VFR/MVFR. CHC -SHRA.
MON-TUE...VFR. NO SIG WX.
&&
.FIRE WEATHER...
NO FIRE WEATHER RELATED ISSUED ARE EXPECTED THROUGH THE PERIOD. ISOLATED
TO SCATTERED SHOWERS AND THUNDERSTORMS WILL OCCUR INTO THIS
EVENING AS ANOTHER WEAK FRONTAL BOUNDARY CROSSES THE AREA. THE
FRONT WILL THEN STALL SOUTH AND EAST OF THE REGION FRIDAY...BEFORE
A STRONGER FRONT APPROACHES FROM THE WEST LATE SATURDAY BRINGING
THE POTENTIAL FOR A WIDESPREAD SOAKING RAINFALL.
&&
.HYDROLOGY...
A WEAK FRONTAL BOUNDARY WILL BRING ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS THIS EVENING. MOST AREAS WILL REMAIN DRY...ALTHOUGH
SOME LOCATIONS COULD RECEIVE A QUICK QUARTER TO HALF INCH OF RAIN.
ANY BRIEF...DOWNPOURS COULD LEAD TO TEMPORARY PONDING OF WATER IN
LOW LYING...POOR DRAINAGE AND URBAN AREAS.
A FEW MORE SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ON
FRIDAY WITH THE FRONT LINGERING ACROSS THE SOUTHEAST PORTION OF THE
HSA. A MORE WIDESPREAD RAINFALL COULD OCCUR THIS WEEKEND...AS A
FRONTAL BOUNDARY AND LOW PRESSURE SYSTEM APPROACH FROM THE MIDWEST
AND OHIO VALLEY. AT THIS TIME THE SPEED OF MOVEMENT OF THIS SYSTEM
IS UNCERTAIN...WHICH WILL HAVE AN IMPACT ON RAINFALL AMOUNTS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...KL/JPV
NEAR TERM...KL
SHORT TERM...KL
LONG TERM...BGM
AVIATION...BGM
FIRE WEATHER...KL
HYDROLOGY...KL/JPV
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
354 PM EDT Thu Sep 6 2012
.NEAR TERM [Through Tonight]...
Despite the normally favorable Sea Breeze Flow for convection
(with a 1000-700 mb Mean Layer Vector Wind (MLVW) out of the SSE
at 10 to as high as 10 to 15 kts (Type 6 or 7 Regime)), the
showers and storms have not been quite as numerous as earlier
expected. This could be due to some mid-upper level dry air
entrainment from the NNE, as PWATs have fallen from the 2.1"-2.2"
yesterday to around 1.8" this afternoon. Therefore, will plan on
trimming PoPs back a bit for the remainder of the day based on
current Radar and Satellite Trends, as well as the near term fcsts
from the HRRR and Hi-Res WRFs. The favored area thus far has been
the SE FL Big Bend and the Adjacent Coastal Waters, with the
convection over the Panhandle waters dissipating, possibly in
response to the remnants of Isaac pulling moisture off to the SW.
For tonight, PoPs may be a bit tricky over the interior for a few
hours this evening (but generally in the 20-30% range), but should
be able to bump up PoPs to at least 30% over the Coastal Waters
from 06-12 UTC.
&&
.SHORT TERM [Friday Through Sunday]...
The period starts with a north/south split pattern. To the north,
deep low pressure spins over western Quebec with a trough
extending west/southwest through the Northern Rockies. To the
south, deep layer high pressure is centered over the Southern
Plains sprawling the Southwest to the Lower Mississippi Valley. At
the surface, much of the local area is covered by a weak flow
regime under the influence of the subtropical ridge. Along the
western edge of the ridge, a weak area of low pressure spins
across the northern Gulf of Mexico, just south of New Orleans.
Through the weekend, the northern trough will dig through the
Plains and the Mississippi Valley, into the southeast, and
eventually depart the Mid-Atlantic coast. The Gulf low will
meander south of Louisiana until it begins to feel the effects of
the approaching trough/sfc front. This will likely occur some time
on Saturday, when the low will pull northeast across Florida.
Where the low actually traverses the state is still a bit
uncertain, but at this point it appears as though the low will
open up ahead of the sfc front off of the Panhandle coast and move
northeast across north Florida and extreme south Georgia. The bulk
of the rainfall associated with this low will likely remain across
the Gulf and the southeast Big Bend of Florida. In the wake of the
low, a small sliver of dry air will precede the front and result
in a brief period of drying on Saturday night. The front, in the
form of a broken line of widely scattered showers and isolated
thunderstorms will work its way through the local area through the
day on Sunday. There is a slight chance for a severe storm or two
as the front approaches the southeast Big Bend on Sunday
afternoon, where peak heating will result in increased instability
that will couple with 30 to 35 knots of deep layer shear. However,
the severe weather potential is highly dependent on the timing of
the front which is still rather uncertain.
&&
.LONG TERM [Monday through Wednesday]...
The extended period will be dominated by rather nice weather.
Behind the front, don`t expect a marked drop in afternoon
temperatures, however, it appears as though we will dry out rather
nicely for this time of year. This will make the afternoons feel
comfortable, and provide us with cool temperatures in the middle
60s overnight.
&&
.AVIATION [Beginning 20Z Thursday]...
VFR conditions should prevail across the region this afternoon and
evening, although isolated thunderstorms are possible. Showers and
thunderstorms, if they materialize, should end by 00Z. Overnight,
some fog is expected to develop everywhere except ECP. vsbys may dip
to MVFR at sites with fog. At VLD, cigs with fog may dip to IFR.
&&
.MARINE...
The forecast over the Coastal Waters during the next several days
will be highly dependent on the potential development, intensity,
and track of the presently weak low positioned in the northern
Gulf of Mexico. At present, winds and seas are expected to remain
below headline criteria (just below in some cases) for the much of
the remainder of the week and weekend before increasing over by
late Sunday night and early next week as the low moves back to the
northeast or east-northeast. Mariners are urged to keep a close
eye on the forecast over the next several days.
&&
.FIRE WEATHER...
Between the low in the northern Gulf and a cold front forecast to
affect the region Saturday night into Sunday, the area will probably
see rain most of the weekend. From Sunday afternoon and beyond, POPs
drop, however at this time relative humidity values are expected to
remain above criteria values so no fire weather hazards are
anticipated at this time.
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Gould
SHORT TERM...Harrigan
LONG TERM...Harrigan
AVIATION...Moore
MARINE...Gould
FIRE WEATHER...Moore
AREA FORECAST DISCUSSION
NWS GOODLAND KS
303 PM MDT THU SEP 6 2012
.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 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1130 AM MDT THU SEP 6 2012
VFR CONDITIONS ARE EXPECTED TO PREVAIL AT BOTH KGLD AND KMCK
THROUGH THE PERIOD. THUNDERSTORM ACTIVITY SHOULD REMAIN SOUTHEAST
OF BOTH TERMINALS...WITH LOW PROBABILITY OF A THUNDERSTORM AT
KGLD. DO NOT PLAN ON INCLUDING IN TAFS AT THIS TIME DUE TO
LIMITED COVERAGE. WINDS AT KMCK WILL REMAIN GUSTY THIS AFTERNOON
AHEAD OF SURFACE TROUGH...WITH WINDS DECREASING AND BECOMING
VARIABLE AT BOTH TERMINALS AS THIS SHIFTS EAST. COLD FRONT WILL
BRING GUSTY NORTH WINDS LATE TONIGHT THROUGH FRIDAY MORNING. A FEW
GUSTS IN EXCESS OF 40KT CANT BE RULED OUT...HOWEVER PREVAILING
GUSTS SHOULD BE IN THE 30-40KT RANGE AT BOTH TERMINALS. MAY NEED
TO INCREASE BASED ON TRENDS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...LOCKHART
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
236 PM MDT THU SEP 6 2012
.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 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1130 AM MDT THU SEP 6 2012
VFR CONDITIONS ARE EXPECTED TO PREVAIL AT BOTH KGLD AND KMCK
THROUGH THE PERIOD. THUNDERSTORM ACTIVITY SHOULD REMAIN SOUTHEAST
OF BOTH TERMINALS...WITH LOW PROBABILITY OF A THUNDERSTORM AT
KGLD. DO NOT PLAN ON INCLUDING IN TAFS AT THIS TIME DUE TO
LIMITED COVERAGE. WINDS AT KMCK WILL REMAIN GUSTY THIS AFTERNOON
AHEAD OF SURFACE TROUGH...WITH WINDS DECREASING AND BECOMING
VARIABLE AT BOTH TERMINALS AS THIS SHIFTS EAST. COLD FRONT WILL
BRING GUSTY NORTH WINDS LATE TONIGHT THROUGH FRIDAY MORNING. A FEW
GUSTS IN EXCESS OF 40KT CANT BE RULED OUT...HOWEVER PREVAILING
GUSTS SHOULD BE IN THE 30-40KT RANGE AT BOTH TERMINALS. MAY NEED
TO INCREASE BASED ON TRENDS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
149 PM MDT THU SEP 6 2012
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
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 WEDNESDAY)
ISSUED AT 249 AM MDT THU SEP 6 2012
TOMORROW NIGHT-SATURDAY NIGHT...MUCH QUIETER WEATHER EXPECTED FOR
THE PERIOD AS COOL HIGH PRESSURE SETTLES OVER THE AREA. WITH LIGHT
WINDS...CLEAR SKIES AND MUCH DRIER AIR THINK TEMPERATURES HAVE THE
POTENTIAL TO BE THE COOLEST OF THE SEASON WITH TEMPERATURES DIPPING
INTO THE 40S BOTH EVENINGS AND COULD POSSIBLE SEE AN UPPER 30S IN
SOME OF THE LOW SPOTS. OTHERWISE EXPECT AFTERNOON HIGHS TO WARM BACK
INTO THE LOW 80S DESPITE THE COOLER MORNING STARTS.
A BROAD RIDGE WILL GRADUALLY BUILD INTO THE CENTRAL PLAINS AS
SURFACE HIGH PRESSURE MOVES INTO THE MISSOURI AND OHIO RIVER VALLEYS
BY EARLY NEXT WEEK...RESULTING IN QUIET WEATHER THROUGH THE EARLY
EXTENDED PERIOD. BY MONDAY AFTERNOON...STRONG LEE TROUGHING WILL
DEVELOP AHEAD OF AN UPPER LEVEL TROUGH THAT WILL SWING OUT OF
SOUTHWESTERN CANADA AND THROUGH THE NORTHERN ROCKIES. THE
ATTENDANT COLD FRONT WILL MOVE ACROSS THE REGION TUESDAY AFTERNOON
AND EVENING BRINGING ANOTHER CHANCE FOR THUNDERSTORMS THROUGH
EARLY WEDNESDAY MORNING.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1130 AM MDT THU SEP 6 2012
VFR CONDITIONS ARE EXPECTED TO PREVAIL AT BOTH KGLD AND KMCK
THROUGH THE PERIOD. THUNDERSTORM ACTIVITY SHOULD REMAIN SOUTHEAST
OF BOTH TERMINALS...WITH LOW PROBABILITY OF A THUNDERSTORM AT
KGLD. DO NOT PLAN ON INCLUDING IN TAFS AT THIS TIME DUE TO
LIMITED COVERAGE. WINDS AT KMCK WILL REMAIN GUSTY THIS AFTERNOON
AHEAD OF SURFACE TROUGH...WITH WINDS DECREASING AND BECOMING
VARIABLE AT BOTH TERMINALS AS THIS SHIFTS EAST. COLD FRONT WILL
BRING GUSTY NORTH WINDS LATE TONIGHT THROUGH FRIDAY MORNING. A FEW
GUSTS IN EXCESS OF 40KT CANT BE RULED OUT...HOWEVER PREVAILING
GUSTS SHOULD BE IN THE 30-40KT RANGE AT BOTH TERMINALS. MAY NEED
TO INCREASE BASED ON TRENDS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...JRM/PMM
AVIATION...DR
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
201 PM CDT THU SEP 6 2012
.DISCUSSION...
CUMULUS FIELD IS FINALLY DEVELOPING...BUT WE MAY BE SEEING SOME
COMPRESSIONAL HEATING AHEAD OF THE APPROACHING CLOUDS EDGING
TOWARD THE NW CORNER OF THE CWA AT THIS TIME. UNDER THE CLOUDS LOW
90S RESIDE AND HAVE DEVELOPED A SUBSTANTIAL AREA OF DIFFERENTIAL
HEATING. WE HAVE RAISED TEMPS FOR THE NEXT COUPLE OF HOURS WHICH
ADMITTEDLY REALLY NEEDS THE CLOUDS TO HELP SOON. HEAT INDICES WILL
BE CLOSE...BUT MID 50S ARE A BIG HELP OVER NE TX...SE OK...AND
PERHAPS EVEN SW AR SOON. NEW ZONES ALREADY OUT. /24/
&&
.PREV DISCUSSION... /ISSUED 1129 AM CDT THU SEP 6 2012/
DISCUSSION...
SKIES BECOMING FAIR LATE THIS MORNING WITH A WEAK MID LEVEL
DISTURBACNE WHICH HAD SOME SHOWERS EARLIER ALONG AND SOUTH OF I-20
NOW MAY END UP YIELDING LITTLE IF ANY DURING THE AFTERNOON...BUT A
SLIGHT CHANCE WAS ADDED FOR THE SE ZONES. ALSO AND SLIGHTLY MORE
IMPRESSIVE QPF WISE THE SYSTEM RIDING ALONG THE RED RIVER OF
OK/TX. THIS IS LIKEWISE MORE OF A MID LEVEL SYSTEM...BUT THERE IS
SOME WEAK SFC CONVERGENCE IN PLAY AS WELL. NAM AND RAP MODELS
GENERATE SOME QPF FOR NE TX AND SE OK AS THIS SYSTEM WORKS EAST.
SHOULD ANYTHING BECOME SFC BASED THIS AFTERNOON...THEN CONVECTIVE
OUTFLOW WILL CONTINUE SHOWERS AND ISOLATED THUNDER TO JUST BEYOND
SUNSET IN THE I-30 CORRIDOR. FOR NOW HAVE ADDED NE TX/SE OK WITH A
SLIGHT CHANCE FOR THIS AFTERNOON.
OUR WARM SPOT IS IDABEL OK ALREADY AT 97...BUT THEIR DEW POINT IS
TOO LOW FOR THE HX TO BE ANY HIGHER THAN THE AIR TEMP AND WITH
INCREASING CLOUDS FOR THE LATE DAY...HAVE TOPPED SE OK EARLY THIS
AFTERNOON TEMP WISE AND REMOVED THE HEAT ADV FROM SE OK/ ADJACENT
NE TX. A FEW OTHER CHANGES TO HIGHS BASED ON TRENDS...BUT WILL
CONTINUE THE HEAT ADVISORY FROM NOON TO 7PM FOR AR/LA IN CWA. /24/
AVIATION...
MOSTLY VFR FLIGHT CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD.
STILL SEEING LOW MVFR CIGS WHICH HAVE DEVELOPED OVER PORTIONS OF
DEEP E TX AFFECTING THE LFK TERMINAL...BUT THESE SHOULD SCATTER OUT
SHORTLY ONCE MIXING INCREASES. ALSO SEEING AN ACCAS FIELD ALONG THE
I-20 CORRIDOR OF EXTREME E TX/N LA...WHICH HAS GENERATED VERY
ISOLATED BUT ELEVATED -SHRA OVER THESE AREAS. HOWEVER...THIS CLOUD
FIELD SHOULD DISSIPATE BY MIDDAY/EARLY AFTERNOON...WITH A SCT CU
FIELD /AT BEST/ DEVELOPING AFTER 19Z ACROSS THE REGION...MORESO OVER
NCNTRL LA/SE AR. A WEAK SHORTWAVE OVER CNTRL OK WILL SHIFT E INTO SE
OK/WRN AR BY MID TO LATE AFTERNOON...WHICH MAY YIELD WIDELY SCT
ELEVATED CONVECTION OVER THESE AREAS...BUT SHOULD REMAIN N OF THE
TXK/ELD TERMINALS BEFORE DIMINISHING THIS EVENING WITH THE LOSS OF
HEATING. ASIDE FROM CIRRUS FROM THIS CONVECTION/DISTURBANCE
AFFECTING MAINLY THE AR TERMINALS OVERNIGHT...SKC WILL PREVAIL
ELSEWHERE THROUGH THE REMAINDER OF THE TAF PERIOD. SSW WINDS 4-7KTS
OVER E TX THIS AFTERNOON WILL BECOME LIGHT S AFTER 00Z. LIGHT S
WINDS ARE EXPECTED ELSEWHERE ACROSS SW AR/N LA DURING THE NEXT 24
HOURS. /15/
PREV DISCUSSION... /ISSUED 349 AM CDT THU SEP 6 2012/
DISCUSSION...
SAME OLD STORY AGAIN FOR TODAY...WITH THE UPPER RIDGE STILL
ANCHORED OVER W TX. A STALLED FRONTAL BOUNDARY PRESENT ACROSS SRN
OK/AR WILL AID ISOLD TO SCT CONVECTION ACROSS SE OK/SW AR. SOME
ADDITIONAL CLOUD COVER OVER THESE AREAS MAY KEEP TEMPS DOWN A
DEGREE OR TWO FROM WEDNESDAY`S HIGHS...BUT STILL WARM ENOUGH TO
PUSH HEAT INDICES TOWARD HEAT ADVISORY CRITERIA. FURTHER S INTO
LA...WARMER TEMPS AND LESS MIXING WILL ALSO PUSH HEAT INDICES
UPWARD. HAVE DECIDED TO GO WITH THE HEAT ADVISORY AGAIN FOR
TODAY ACROSS NE TX...SE OK...SW AR...NW AND N CENTRAL LA...THE
SAME AREA WE HAVE SEEN IN THE LAST FEW DAYS. AS IN PREVIOUS
DAYS...HEAT INDICES AT A FEW SPOTS MAY BRIEFLY REACH 105 DEGREES...
BUT THESE OCCURRENCES SHOULD BE ISOLD. FRIDAY IS SHAPING UP TO BE
QUITE WARM AS WELL...SO MAY SEE THE HEAT ADVISORY EXTENDED FOR ONE
MORE DAY IN LATER PACKAGES.
UPPER TROF OVER EXTREME SWRN CANADA WILL CONTINUE DIGGING SE
ACROSS THE PLAINS THROUGH FRIDAY...BRINGING A COLD FRONT AND RAIN
CHANCES BEGINNING LATE FRIDAY NIGHT AND CONTINUING THROUGH MOST OF
THE DAY SATURDAY. SOME POTENTIAL FOR A FEW SEVERE STORMS DOES
EXIST...BUT APPEARS THAT THIS THREAT WILL MAINLY BE CONFINED TO
PARTS OF SW AR/N CENTRAL LA. AS HAS BEEN DISCUSSED OVER THE LAST
FEW MORNINGS...SIGNIFICANTLY COOLER TEMPS AND DRIER AIR ARE
EXPECTED BEHIND THE FRONT AS HIGH PRESSURE BUILDS IN THE WAKE OF
THE TROF BY SATURDAY EVENING.
THE UPPER RIDGE IS FCST TO BEGIN REINFORCING ITSELF BACK OVER THE
SRN PLAINS BY EARLY IN THE WORK WEEK...WHICH WILL HELP TEMPS WARM
BACK TO NEAR NORMAL FOR THE REMAINDER OF THE PD. MODELS HINTING AT
A DISTURBANCE IN THE NRN GULF BY MIDWEEK WHICH IS CURRENTLY FCST
TO TRAVERSE THE NRN GULF COAST THROUGH THE END OF THE PD. HOWEVER...
IT APPEARS ATTM THAT THIS FEATURE WILL HAVE VERY LITTLE IMPACT ON
OUR REGION...EXCEPT FOR BRINGING SOME PARTLY CLOUDY SKIES BACK. /12/
AVIATION...
MOSTLY VFR FLIGHT WEATHER TODAY AND TONIGHT. ONLY EXCEPTION MAY BE
PATCHY CIGS AROUND 15 HUNDRED FEET THIS MORNING ACROSS DEEP EAST
TEXAS BETWEEN 12Z AND 14Z. AFTER 18Z AND CONTINUING UNTIL AROUND
SUNSET...EXPECT ISOLATED TSTMS ALONG AND NORTH OF A IDABEL OK TO
MONROE LA LINE. SURFACE WIND SOUTH TO SOUTHWEST 5 TO 10 KTS EARLY
THIS MORNING BECOMING WEST TO SOUTHWEST AFTER 15Z. /14/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 102 76 101 75 86 / 10 10 10 30 40
MLU 100 75 99 74 88 / 10 10 10 30 40
DEQ 106 70 99 66 82 / 20 10 30 50 20
TXK 104 75 100 71 83 / 10 10 20 50 30
ELD 101 73 99 69 85 / 10 10 20 50 40
TYR 101 77 101 75 85 / 10 10 10 20 20
GGG 103 77 101 75 86 / 10 10 10 20 30
LFK 100 75 100 75 91 / 10 10 10 20 40
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING
ZONES: ARZ050-051-059>061-070>073.
LA...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING
ZONES: LAZ001>006-010>014-017>022.
OK...NONE.
TX...NONE.
&&
$$
24
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
1129 AM CDT THU SEP 6 2012
.DISCUSSION...
SKIES BECOMING FAIR LATE THIS MORNING WITH A WEAK MID LEVEL
DISTURBACNE WHICH HAD SOME SHOWERS EARLIER ALONG AND SOUTH OF I-20
NOW MAY END UP YIELDING LITTLE IF ANY DURING THE AFTERNOON...BUT A
SLIGHT CHANCE WAS ADDED FOR THE SE ZONES. ALSO AND SLIGHTLY MORE
IMPRESSIVE QPF WISE THE SYSTEM RIDING ALONG THE RED RIVER OF
OK/TX. THIS IS LIKEWISE MORE OF A MID LEVEL SYSTEM...BUT THERE IS
SOME WEAK SFC CONVERGENCE IN PLAY AS WELL. NAM AND RAP MODELS
GENERATE SOME QPF FOR NE TX AND SE OK AS THIS SYSTEM WORKS EAST.
SHOULD ANYTHING BECOME SFC BASED THIS AFTERNOON...THEN CONVECTIVE
OUTFLOW WILL CONTINUE SHOWERS AND ISOLATED THUNDER TO JUST BEYOND
SUNSET IN THE I-30 CORRIDOR. FOR NOW HAVE ADDED NE TX/SE OK WITH A
SLIGHT CHANCE FOR THIS AFTERNOON.
OUR WARM SPOT IS IDABEL OK ALREADY AT 97...BUT THEIR DEW POINT IS
TOO LOW FOR THE HX TO BE ANY HIGHER THAN THE AIR TEMP AND WITH
INCREASING CLOUDS FOR THE LATE DAY...HAVE TOPPED SE OK EARLY THIS
AFTERNOON TEMP WISE AND REMOVED THE HEAT ADV FROM SE OK/ ADJACENT
NE TX. A FEW OTHER CHANGES TO HIGHS BASED ON TRENDS...BUT WILL
CONTINUE THE HEAT ADVISORY FROM NOON TO 7PM FOR AR/LA IN CWA. /24/
&&
.AVIATION...
MOSTLY VFR FLIGHT CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD.
STILL SEEING LOW MVFR CIGS WHICH HAVE DEVELOPED OVER PORTIONS OF
DEEP E TX AFFECTING THE LFK TERMINAL...BUT THESE SHOULD SCATTER OUT
SHORTLY ONCE MIXING INCREASES. ALSO SEEING AN ACCAS FIELD ALONG THE
I-20 CORRIDOR OF EXTREME E TX/N LA...WHICH HAS GENERATED VERY
ISOLATED BUT ELEVATED -SHRA OVER THESE AREAS. HOWEVER...THIS CLOUD
FIELD SHOULD DISSIPATE BY MIDDAY/EARLY AFTERNOON...WITH A SCT CU
FIELD /AT BEST/ DEVELOPING AFTER 19Z ACROSS THE REGION...MORESO OVER
NCNTRL LA/SE AR. A WEAK SHORTWAVE OVER CNTRL OK WILL SHIFT E INTO SE
OK/WRN AR BY MID TO LATE AFTERNOON...WHICH MAY YIELD WIDELY SCT
ELEVATED CONVECTION OVER THESE AREAS...BUT SHOULD REMAIN N OF THE
TXK/ELD TERMINALS BEFORE DIMINISHING THIS EVENING WITH THE LOSS OF
HEATING. ASIDE FROM CIRRUS FROM THIS CONVECTION/DISTURBANCE
AFFECTING MAINLY THE AR TERMINALS OVERNIGHT...SKC WILL PREVAIL
ELSEWHERE THROUGH THE REMAINDER OF THE TAF PERIOD. SSW WINDS 4-7KTS
OVER E TX THIS AFTERNOON WILL BECOME LIGHT S AFTER 00Z. LIGHT S
WINDS ARE EXPECTED ELSEWHERE ACROSS SW AR/N LA DURING THE NEXT 24
HOURS. /15/
&&
.PREV DISCUSSION... /ISSUED 349 AM CDT THU SEP 6 2012/
DISCUSSION...
SAME OLD STORY AGAIN FOR TODAY...WITH THE UPPER RIDGE STILL
ANCHORED OVER W TX. A STALLED FRONTAL BOUNDARY PRESENT ACROSS SRN
OK/AR WILL AID ISOLD TO SCT CONVECTION ACROSS SE OK/SW AR. SOME
ADDITIONAL CLOUD COVER OVER THESE AREAS MAY KEEP TEMPS DOWN A
DEGREE OR TWO FROM WEDNESDAY`S HIGHS...BUT STILL WARM ENOUGH TO
PUSH HEAT INDICES TOWARD HEAT ADVISORY CRITERIA. FURTHER S INTO
LA...WARMER TEMPS AND LESS MIXING WILL ALSO PUSH HEAT INDICES
UPWARD. HAVE DECIDED TO GO WITH THE HEAT ADVISORY AGAIN FOR
TODAY ACROSS NE TX...SE OK...SW AR...NW AND N CENTRAL LA...THE
SAME AREA WE HAVE SEEN IN THE LAST FEW DAYS. AS IN PREVIOUS
DAYS...HEAT INDICES AT A FEW SPOTS MAY BRIEFLY REACH 105 DEGREES...
BUT THESE OCCURRENCES SHOULD BE ISOLD. FRIDAY IS SHAPING UP TO BE
QUITE WARM AS WELL...SO MAY SEE THE HEAT ADVISORY EXTENDED FOR ONE
MORE DAY IN LATER PACKAGES.
UPPER TROF OVER EXTREME SWRN CANADA WILL CONTINUE DIGGING SE
ACROSS THE PLAINS THROUGH FRIDAY...BRINGING A COLD FRONT AND RAIN
CHANCES BEGINNING LATE FRIDAY NIGHT AND CONTINUING THROUGH MOST OF
THE DAY SATURDAY. SOME POTENTIAL FOR A FEW SEVERE STORMS DOES
EXIST...BUT APPEARS THAT THIS THREAT WILL MAINLY BE CONFINED TO
PARTS OF SW AR/N CENTRAL LA. AS HAS BEEN DISCUSSED OVER THE LAST
FEW MORNINGS...SIGNIFICANTLY COOLER TEMPS AND DRIER AIR ARE
EXPECTED BEHIND THE FRONT AS HIGH PRESSURE BUILDS IN THE WAKE OF
THE TROF BY SATURDAY EVENING.
THE UPPER RIDGE IS FCST TO BEGIN REINFORCING ITSELF BACK OVER THE
SRN PLAINS BY EARLY IN THE WORK WEEK...WHICH WILL HELP TEMPS WARM
BACK TO NEAR NORMAL FOR THE REMAINDER OF THE PD. MODELS HINTING AT
A DISTURBANCE IN THE NRN GULF BY MIDWEEK WHICH IS CURRENTLY FCST
TO TRAVERSE THE NRN GULF COAST THROUGH THE END OF THE PD. HOWEVER...
IT APPEARS ATTM THAT THIS FEATURE WILL HAVE VERY LITTLE IMPACT ON
OUR REGION...EXCEPT FOR BRINGING SOME PARTLY CLOUDY SKIES BACK. /12/
AVIATION...
MOSTLY VFR FLIGHT WEATHER TODAY AND TONIGHT. ONLY EXCEPTION MAY BE
PATCHY CIGS AROUND 15 HUNDRED FEET THIS MORNING ACROSS DEEP EAST
TEXAS BETWEEN 12Z AND 14Z. AFTER 18Z AND CONTINUING UNTIL AROUND
SUNSET...EXPECT ISOLATED TSTMS ALONG AND NORTH OF A IDABEL OK TO
MONROE LA LINE. SURFACE WIND SOUTH TO SOUTHWEST 5 TO 10 KTS EARLY
THIS MORNING BECOMING WEST TO SOUTHWEST AFTER 15Z. /14/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 101 76 101 75 86 / 10 10 10 30 40
MLU 99 75 99 74 88 / 10 10 10 30 40
DEQ 100 70 99 66 82 / 20 10 30 50 20
TXK 101 75 100 71 83 / 10 10 20 50 30
ELD 99 73 99 69 85 / 10 10 20 50 40
TYR 98 77 101 75 85 / 10 10 10 20 20
GGG 100 77 101 75 86 / 10 10 10 20 30
LFK 100 75 100 75 91 / 10 10 10 20 40
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING
ZONES: ARZ050-051-059>061-070>073.
LA...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING
ZONES: LAZ001>006-010>014-017>022.
OK...NONE.
TX...NONE.
&&
$$
24/15
AREA FORECAST DISCUSSION
NWS GAYLORD MI
129 PM EDT THU SEP 6 2012
.SYNOPSIS...
ISSUED AT 327 AM EDT THU SEP 6 2012
A RELATIVELY ACTIVE PERIOD OF WEATHER IS EXPECTED THROUGH THE END OF
THE WEEK...AS ADDITIONAL DISTURBANCES ROTATE THROUGH THE REGION. A
BRIEF BREAK IN THE ACTIVE WEATHER IS EXPECTED INTO THIS EVENING...
WITH RAIN CHANCES INCREASING AGAIN LATER TONIGHT THROUGH FRIDAY. A
GENERALLY DRY AND MUCH COOLER WEEKEND IS EXPECTED...WITH JUST
PERHAPS A FEW LIGHT SHOWERS RETURNING FOR SATURDAY NIGHT. SLOWLY
MODERATING CONDITIONS ARE EXPECTED NEXT WORK WEEK.
&&
.UPDATE...
ISSUED AT 129 PM EDT THU SEP 6 2012
GOTTA LOVE PESKY FORECASTS LIKE THIS ONE! JUST LIKE THAT...A
COUPLE OF SHOWERS FIRED OFF NEAR GRAND TRAVERSE BAY...WITHIN THE
ENHANCED STRATOCU FIELD THAT HAS PLAGUED MUCH OF NORTHWEST LOWER
THROUGH THE MORNING. THESE WILL LIKELY CONTINUE TO WORK EAST THE
NEXT FEW HOURS...WITH POSSIBLY A FEW MORE DEVELOPING INTO
NORTHEAST LOWER AS WELL PER LATEST SHORT TERM GUIDANCE TRENDS.
ALSO LIKE THE EARLIER CALL FOR A FEW POSSIBLE SHOWERS OVER THE
EASTERN U.P. WHERE CU FIELD IS CURRENTLY DEVELOPING BENEATH MORE
PRONOUNCED UPPER COOL POOL. OUTSIDE OF THESE SHOWERS...GOING FCST
IS IN GOOD SHAPE AND HAVE MADE NO OTHER CHANGES.
UPDATE ISSUED AT 1016 AM EDT THU SEP 6 2012
FAIRLY QUIET WEATHER ACROSS THE REGION THROUGH THE DAY...BUT NOT
WITHOUT OUR FAIR SHARE OF "ISSUES" AS WE HEAD INTO THE AFTERNOON.
THE FIRST IS CLOUD COVER. HAVE SEEN QUITE THE PESKY PLUME OF BOTH
LOW AND MID CLOUDS ACROSS PARTS OF NORTHERN LOWER SINCE JUST
BEFORE SUNRISE...WITH THE MID CLOUDS BEING DRIVEN MAINLY BE
REMNANT WEAKISH INSTABILITY ABOVE A STEEPER 775-700MB LAPSE RATE
PLUME (SEE 12Z APX RAOB FOR HINTS OF THIS). EARLIER LAKE MICHIGAN
CONVECTION (AND SUBSEQUENT MID CLOUD FOR THAT MATTER) WAS LIKELY
DRIVEN BY LOW LEVEL PARCELS BEING LOFTED INTO THIS REMAINING
SKINNY INSTABILITY PLUME...WITH SOME HINTS THIS OCCURRED DUE TO A
NOTABLE MID LAKE (LAND BREEZE INDUCED?) CONVERGENCE AXIS. SUSPECT
THESE PESKY CLOUDS WILL HANG AROUND FOR A WHILE INTO
MIDDAY...WHILE LOWER STUFF GRADUALLY MIXES OUT. WILL PROBABLY SEE
AN OK AMOUNT OF DIURNAL CU DEVELOPMENT AS WELL...PARTICULARLY OVER
NORTHEAST LOWER AND INTERIOR EASTERN UPPER WHERE MEAN LOW LEVEL
WESTERLY FLOW WILL FAVOR BEST LAKE BREEZE CONVERGENCE.
WILL ALSO BE WATCHING WIND/DEW POINT TRENDS INTO THE AFTERNOON.
PER UPSTREAM POST-FRONTAL OBS IN MINNESOTA YESTERDAY...MIXING
ENDED UP DEEPER THAN PROGGED...AND SUSPECT THIS WILL BE THE CASE
HERE AS WELL (12Z APX RAOB LOOKS A LOT LIKE 12Z MPX ONE
YESTERDAY). AS SUCH...HAVE BOOSTED GUSTS THIS AFTN ALONG WITH
LOWERING DEW POINTS INTO THE 40S IN SPOTS. THIS STILL WON`T BE
ENOUGH TO GIVE US ANY BIG FIRE WX ISSUES...BUT MIN RH VALUES
SHOULD DIP WELL INTO THE 30S.
FINALLY...WILL HAVE TO WATCH THE POTENTIAL FOR SOME ISOLATED AFTN
SHOWERS OVER MAINLY EASTERN UPPER. THIS AREA WILL BE FAVORED BY
BEST LOW LEVEL CONVERGENCE BENEATH A SHARPER UPPER COOL POOL. PER
LATEST RUC FORECAST RAOBS...CAN ENVISION SQUEEZING OUT ENOUGH CAPE
(MAYBE 100-200J/KG) TO GIVE US A FEW SNEAKY SHOWERS. MEANWHILE...
DON`T FORESEE THIS HAPPENING ACROSS NORTHEAST LOWER WHERE RESIDUAL
CAP IN PLACE SHOULD KEEP THINGS IN CHECK. CERTAINLY WILL HAVE TO
KEEP AN EYE ON THIS THOUGH.
HAVE RAISED GOING HIGHS A COUPLE OF DEGREES PER LATEST TRENDS AND
LACK OF ANY REAL ONGOING ADVECTION TODAY. WILL SEE READINGS RANGE
FROM THE MID 70S FAR NORTH TO AROUND 80 ACROSS MANY SPOTS FOR
NORTHERN LOWER.
UPDATE ISSUED AT 621 AM EDT THU SEP 6 2012
FAIRLY QUIET CONDITIONS THIS MORNING WITH CLEAR TO PARTLY CLOUDY
SKIES AND PATCHY DENSE FOG OUT THERE. HOT SPOT OF CONVECTION OVER
CENTRAL LAKE MICHIGAN...JUST WEST OF MANISTEE OVER THE LAST FEW
HOURS...WITH A NUMBER OF SMALL SHOWERS (EVEN SOME THUNDER) COMING
ONSHORE IN THAT AREA BUT DYING SOON AFTER. IN ANY EVENT...HAVE
ISOLATED SHOWERS/THUNDER IN THAT AREA THROUGH 12Z...HOPEFULLY THAT
WILL BE LONG ENOUGH.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 327 AM EDT THU SEP 6 2012
MID-UPPER LOW LOCATED OVER NRN MANITOBA/NW ONTARIO WITH BROAD
TROUGHING SPANNING MUCH OF THE NRN CONUS. SHORT WAVE IMPULSE
DROPPING DOWN INTO THE NRN ROCKIES ACCOMPANIED BU A DEVELOPING
WEST-EAST UPPER JET CORE ACROSS THE NRN PLAINS. SHORT WAVE IMPULSE
AND UPPER JET FEATURE WILL BE THE NEXT WEATHER MAKER FOR THE WESTERN
GREAT LAKES...AS IT PUNCHES INTO THE REGION AND ULTIMATELY CARVES
OUT A FAIRLY SUBSTANTIAL TROUGH THROUGH THE WEEKEND. IN THE
MEANTIME...IN THE WAKE OF YESTERDAYS COLD FRONT...ILL DEFINED HIGH
PRESSURE AND A FAIRLY DRY AIRMASS IN THE PROCESS OF BUILDING INTO
THE REGION.
TODAY...OVERALL QUIET AS ILL-DEFINED HIGH PRESSURE SLIDES THROUGH
THE REGION. THAT SAID...THERE IS A LITTLE BIT OF ELEVATED
INSTABILITY WORKING INTO THE REGION FROM THE WEST...EVIDENCED BY THE
POCKETS OF MID CLOUD (ACCAS). WEAK SYNOPTIC FORCING ACROSS LOWER
MICHIGAN AND STRONGER MID LEVEL FLOW HAS SPARKED A LONE ELEVATED
SHOWER OVER CENTRAL LAKE MICHIGAN. WILL KEEP AN EYE ON THAT TO SEE
IF WE HAVE TO ADD ISOLATED POPS TO THE FORECAST ALONG THE M-55
CORRIDOR THIS MORNING. OTHERWISE...COOLER AIR ALOFT/DEEPER MIXED
LAYER AND DAYTIME HEATING WILL LEAD TO SCT-BKN CU DEVELOPMENT TODAY.
FORECAST SOUNDINGS DONT SHOW ENOUGH INSTABILITY TO WARRANT
POPS...BUT DAY CREW WILL NEED TO WATCH FOR ANY HEATING OF THE DAY
INDUCED SHOWERS POPPING UP.
TONIGHT...QUIET EVENING. THEN...AFOREMENTIONED UPSTREAM SHORT WAVE
IMPULSE AND DEVELOPING UPPER JET STREAK WILL ADVANCE ACROSS THE
UPPER MIDWEST AND BEGIN TO PUNCH ACROSS NRN MICHIGAN BY FRIDAY
MORNING. THIS LEADS TO A STRENGTHENING BAND OF MID LEVEL
F-GEN/RESULTING QG-UPWARD ASCENT PUNCHING ACROSS NRN MICHIGAN BY
MORNING (AND EVENTUALLY THROUGH LOWER MICHIGAN ON FRIDAY). CURRENT
TIMING SUGGESTS MOST OF TONIGHT WILL BE DRY...WITH RAINFALL
SPREADING THROUGH EASTERN UPPER MICHIGAN/TIP OF THE MITT TOWARD
MORNING. HAVE TWEAKED FORECAST POPS/WEATHER ACCORDINGLY.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 327 AM EDT THU SEP 6 2012
RATHER BUSY EXTENDED FORECAST...ESPECIALLY DURING THE EARLY
PERIODS...AS ELONGATED CENTRAL CANADA CENTERED TROUGHING MOVES
EAST...PARTIALLY A BY-PRODUCT OF STRONG SHORTWAVE TROUGH ROUNDING
ITS BASE INTO THE LAKES REGION FRIDAY INTO THE WEEKEND. LACK OF
DOWNSTREAM BLOCKING AND MAINTENANCE OF UPSTREAM KICKER SYSTEMS
EXPECTED TO KEEP THIS TROUGH AXIS FAIRLY TRANSIENT...A SOLUTION
GENERALLY NOW WELL GREED UPON BY NEARLY ALL AVAILABLE GUIDANCE.
PATTERN LOOKS TO BECOME A TOUCH MORE ZONAL DURING THE COURSE OF NEXT
WORK WEEK...ONCE AGAIN PROPELLING THE MOST "ACTIVE" WEATHER TO
REGIONS NORTH OF THE BORDER. FORECAST CONCERNS CENTER ON IMPACTS OF
LATE WEEK SYSTEM (BOTH SYNOPTIC AND LAKE ENHANCED/EFFECT RAIN
CHANCES)...AS WELL AS TEMPERATURE AND CLOUD TRENDS THROUGHOUT THE
PERIOD.
STILL APPEARS A DECENT BAND OF MUCH NEEDED RAINFALL WILL DRIFT
SOUTHEAST ACROSS THE NORTH WOODS FRIDAY...COURTESY OF AFOREMENTIONED
APPROACHING STRONG WAVE ENTICING LOW/MID LEVEL FGEN RESPONSE...ALL
OVER-TOPPED BY DECENT EXIT REGION UPPER JET DYNAMICS. DESPITE DECENT
AGREEMENT AMONGST GUIDANCE ON THE ABOVE...RECENT DRY STRETCH OF
WEATHER AND OVERALL THEME OF UNDER-PERFORMING RAIN SYSTEMS LATELY
PREVENTS A CATEGORICAL MENTION (INHERITED LIKELY WILL SUFFICE...WITH
JUST SOME COSMETIC CHANGES ON TIMING). POTENTIAL DOES EXIST FOR AT
LEAST SOME DECENT RAINFALL AS ABOVE DYNAMICS INTERACT WITH AN
APPRECIABLY MOIST AIRMASS (PWAT VALUES AOA 1 INCH). SIGNIFICANT
QUESTIONS START TO ARISE FRIDAY NIGHT INTO SATURDAY AS INITIAL
POSITIVELY TILTED TROUGH CONTINUES TO DIG AND TAKE ON A MORE NEUTRAL
APPEARANCE BY SATURDAY. MODELS CONTINUE TO STRUGGLE WITH JUST HOW
PROGRESSIVE THE ABOVE UNFOLDS...WITH NOW THE NEW 00Z UKMET AND ECMWF
THE MOST AGGRESSIVE IN DRIVING SIGNIFICANT EASTERN LAKES SURFACE LOW
DEVELOPMENT (AND HENCE A SLOWER SOLUTION)...RESULTING IN WIDESPREAD
RAINS HOLDING ON FRIDAY NIGHT INTO SATURDAY FOR NORTHEAST LOWER.
VAST MAJORITY OF OTHER PROGS...INCLUDING THE PREVIOUS MUCH SLOWER
AND WRAPPED-UP NAM-WRF...MORE PROGRESSIVE...DRIVING THE RAIN THREAT
EAST OF THE REGION BY LATER FRIDAY NIGHT. INHERITED FORECAST KINDA
LEFT OPEN THE POSSIBILITY OF THIS SLOWER SCENARIO...AT LEAST KEEPING
SOME RAIN MENTION ACROSS THE SOUTHEAST. GIVEN UNCERTAINTY...CAN
SIMPLY FIND ON COMPELLING ARGUMENT TO DEVIATE FROM THIS PHILOSOPHY.
WILL ALSO NEED TO WATCH FOR SOME LIGHT NORTHERN LAKE MICHIGAN
ENHANCED SHOWERS FRIDAY NIGHT AS NNW FLOW CAA DROPS H85 TEMPERATURES
INTO THE LOWER AND MIDDLE SINGLE DIGITS. ASSUMING THE FASTER IDEA
WORKS OUT...EXPECTING TO SEE A DRY SATURDAY WITH INITIAL LAKE DRIVEN
MORNING CLOUDS GIVING WAY TO WIDESPREAD INTERIOR SC FIELD AS THERMAL
TROUGH LINGERS OVERHEAD. COMBINATION OF CLOUDS/RAIN AND FLOW
BECOMING INCREASINGLY DIRECTED OUT OF CANADA WILL KEEP READINGS BOTH
FRIDAY AND SATURDAY SIGNIFICANTLY COOLER THAT WHAT HAS BEEN OBSERVED
LATELY...WITH HIGHS FRIDAY IN THE 60S AND LOWER 70S...COOLING
FURTHER INTO THE 60S AREA-WIDE SATURDAY.
EVIDENCE CONTINUES TO SUPPORT ADDITIONAL ENERGY DIVING SOUTH ON
BACKSIDE OF HOPEFULLY THEN DEPARTING TROUGH SATURDAY NIGHT...PERHAPS
KICKING OFF A FEW ADDITIONAL LIGHT SHOWERS (LAKE ENHANCED?). BARRING
ANY SIGNIFICANT SURPRISES TO DEPARTURE OF EASTERN LAKES
TROUGHING...REST OF THE FORECAST SHAPING UP TO BE A QUIET ONE AS
FLOW BECOMES MORE ZONAL AND ACTIVE WEATHER SHIFTS NORTH INTO CANADA.
TRENDS STILL SUPPORTING A MOISTURE STARVED COLD FRONTAL PASSAGE
WEDNESDAY...WITH A LOW END SHOWER THREAT ACCOMPANYING IT.
OTHERWISE...MULTI-PERIODS OF DRY WEATHER IS EXPECTED ALONG WITH A
SLOW MODERATING TREND. HIGHS STILL STUCK IN THE 60S ON SUNDAY WILL
GRADUALLY WARM WELL INTO THE 70S BY TUESDAY AND WEDNESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 129 PM EDT THU SEP 6 2012
PESKY CUMULUS AND STRATOCUMULUS WILL CONTINUE TO GRADUALLY WORK
EAST THROUGH THE AFTERNOON...WITH A COUPLE OF SHOWERS ALSO
LIKELY...THOUGH MAINLY IN BETWEEN TERMINAL SITES. SKIES ARE
EXPECTED TO CLEAR FOR A TIME INTO THE EVENING AND FIRST HALF OF
THE OVERNIGHT HOURS...BEFORE MID AND HIGH CLOUDS THICKEN AHEAD OF
OUR NEXT APPROACHING UPPER TROUGH. TIMING OF THESE CLOUDS SHOULD
PREVENT ANY SIGNIFICANT FOG DEVELOPMENT...BUT COULD PERHAPS SEE A
LITTLE SHALLOW GROUND FOG AROUND APN/PLN. APPROACHING UPPER WAVE
WILL BRING WITH IT INCREASING COVERAGE OF LIGHT RAIN THROUGH
FRIDAY MORNING...THOUGH WITH VFR CONDITIONS STILL EXPECTED.
&&
.MARINE...
ISSUED AT 327 AM EDT THU SEP 6 2012
NO MARINE HEADLINES NEEDED AT THIS POINT WITH LIGHTER NW-WESTERLY
WINDS THROUGH TODAY...AND MORE VARIABLE WINDS TONIGHT. SHARP
TROUGH AXIS WILL PASS THROUGH NRN MICHIGAN LATER IN THE DAY
FRIDAY. BEHIND THIS FEATURE...GUSTY NW WINDS WILL DEVELOP LATE
FRIDAY AND FRIDAY NIGHT...WITH SMALL CRAFT HEADLINES POSSIBLE
DURING THAT TIME.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...LAWRENCE
SYNOPSIS...MB
SHORT TERM...BA
LONG TERM...MB
AVIATION...LAWRENCE
MARINE...BA
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
100 PM CDT THU SEP 6 2012
.SHORT TERM...
ISSUED AT 332 AM CDT THU SEP 6 2012
(TODAY THROUGH FRIDAY NIGHT)
STILL EATING CROW AFTER YESTERDAY`S BUSTED FORECAST...AND IT`S A
BITTER BIRD. THE COLD FRONT HAS MADE IT THROUGH KIRKSVILLE BUT IS
TAKING ITS TIME DRIFTING THROUGH THE NORTHWEST PORTION OF THE CWFA.
CURRENT THINKING IS THAT THE FRONT WILL CONTINUE DRIFTING SOUTHEAST
BUT WILL PROBABLY NOT CLEAR THE SOUTHERN PORTION OF THE CWFA BEFORE
AFTERNOON. RAP AND HRRR DEVELOP DECENT INSTABILITY IN EXCESS OF
2000 J/KG WITH LITTLE OR NO CAP. HAVE ADDED POPS SOUTH OF THE STL
METRO AREA ACROSS THE EASTERN OZARKS. ALSO...SINCE THE COLD AIR
ADVECTION IS SOMEWHAT LACKING FROM PREVIOUS FORECASTS...HAVE BUMPED
UP TEMPS A COUPLE OF DEGREES TODAY.
ATTENTION TURNS TO THE STRONG SHORTWAVE JUST NOW DROPPING INTO THE
CONUS FROM SOUTHEAST CANADA AND THE RESULTING STORM WHICH WILL MOVE
THROUGH FRIDAY AND FRIDAY NIGHT. THE WAVE`S PRESENTATION ON WATER
VAPOR IMAGERY IS PRETTY IMPRESSIVE FOR EARLY SEPTEMBER. THIS IS
ENCOURAGING FOR THE FORECAST. LATEST GUIDANCE KEEPS MUCH OF THE
AREA DRY TONIGHT...PRETTY MUCH ALL EXCEPT NORTHEAST MISSOURI AND
WEST CENTRAL ILLINOIS. CAN`T QUITE BRING MYSELF TO PULL POPS OUT OF
THE REST OF THE AREA THO...SO HAVE LEFT THEM BE. ALL GUIDANCE HAS
THE SHORTWAVE DIVING INTO THE PLAINS FRIDAY MORNING AND THE
ASSOCIATED COLD FRONT MOVING THROUGH KIRKSVILLE BY AROUND 18Z. SPC
HAS US OUTLOOKED IN A SLIGHT RISK AND THIS LOOKS GOOD GIVEN THAT THE
NAM DEVELOPS INSTABILITY IN EXCESS OF 3000 J/KG AND PLENTY OF DEEP
LAYER SHEAR. HAVE BUMPED UP POPS TO OCCASIONAL DURING THE AFTERNOON
AND EARLY EVENING FOR PARTS OF THE AREA. LATEST GUIDANCE HAS THE
FRONT MOVING THOUGH FASTER THAN EARLIER FORECAST...SO HAVE CUT BACK
ON POPS AFTER MIDNIGHT.
CARNEY
&&
.LONG TERM...
ISSUED AT 358 AM CDT THU SEP 6 2012
(SATURDAY THROUGH WEDNESDAY)
PRIMARY CHANGE TO THE FORECAST FOR THE LONG TERM IS TO INCREASE HIGH
TEMPERATURES A BIT THIS WEEKEND AND EARLY NEXT WEEK. ALL OF THE
MODELS DROP A STRONG RIDGE INTO THE AREA THIS WEEKEND BEHIND THE
FRONT. WHEN WE INITIALLY BEGAN SEEING THIS STORM SYSTEM IN THE
MODELS SEVERAL DAYS AGO...THEY DEVELOPED A CLOSED LOW OVER THE GREAT
LAKES/OHIO VALLEY REGION. THE PAST FEW RUNS THE MODELS HAVE BECOME
PROGRESSIVE WITH THE WAVE. THIS SHOULD MEAN THAT INSTEAD OF
CONSIDERABLE CLOUDS AND WIDELY SCATTERED SHOWERS ON SATURDAY...IT
SHOULD BE MOSTLY SUNNY AND DRY. WITH THE MORE PROGRESSIVE
SOLUTION...THE WARM UP BACK TO NEAR NORMAL TEMPERATURES SHOULD OCCUR
MORE QUICKLY ON SUNDAY INTO EARLY NEXT WEEK. UPPER LEVEL RIDGE
BUILDS BACK INTO THE AREA BY TUESDAY. ANOTHER COLD FRONT LOOKS TO
BE APPROACHING THE AREA ON WEDNESDAY...BUT HAVE NOT PUT ANY POPS IN
THE FORECAST AT THIS TIME AS THE STRONG SURFACE RIDGE WHICH WILL
BRING US THIS WEEKEND`S COOL WEATHER LOOKS LIKE IT WILL LAY OUT DOWN
ACROSS THE SOUTHERN U.S. AND BLOCK ANY MOIST RETURN FLOW FROM THE
GULF.
CARNEY
&&
.AVIATION...
ISSUED AT 1250 PM CDT THU SEP 6 2012
CLUSTER OF SHOWERS AND THUNDERSTORMS OVER SOUTHWEST MISSOURI IS
TRACKING EASTWARD AND IS EXPECTED TO CONTINUE ON THAT COURSE
THROUGH THE AFTERNOON. THIS SHOULD KEEP IT SOUTH OF THE
TERMINALS...BUT WILL HAVE TO WATCH THE ST LOUIS AREA AS THE FRONT
HAS BECOME QUASI-STATIONARY THROUGH EAST CENTRAL MO AND SOUTHWEST
ILLINOIS. OTHERWISE VFR CONDITIONS EXPECTED THROUGH LATE TONIGHT.
A POTENT COLD FRONT WILL BEGIN TO MOVE INTO NORTHERN MISSOURI AND
WEST CENTRAL ILLINOIS ON FRIDAY MORNING. SHOWERS AND THUNDERSTORMS
SHOULD BE ONGOING ALONG/AHEAD OF THE FRONT LATE TONIGHT AND SHOULD
CONTINUE TO GROW THROUGH THE MORNING AND INTO THE AFTERNOON AS IT
MOVES INTO MO AND IL.
SPECIFICS FOR KSTL...
CLUSTER OF SHOWERS AND THUNDERSTORMS OVER SOUTHWEST MISSOURI IS
TRACKING EASTWARD AND IS EXPECTED TO STAY SOUTH OF THE
TERMINAL...BUT WILL HAVE TO WATCH CLOSELY AS THE FRONT HAS BECOME
QUASI-STATIONARY THROUGH THE ST LOUIS METRO. OTHERWISE VFR
CONDITIONS EXPECTED THROUGH AT LEAST MID MORNING ON FRIDAY.
SHOWERS AND THUNDERSTORMS ARE EXPECTED ALONG AND AHEAD OF A POTENT
COLD FRONT ON FRIDAY...WITH THE BEST CHANCE IN THE 17-21Z TIME
FRAME.
GLASS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1247 PM CDT THU SEP 6 2012
.AVIATION...
VFR IS EXPECTED ALL AREAS THROUGH 06Z THIS EVENING.
06Z-12Z TONIGHT...THEREAFTER A STRONG COLD FRONT MAY BE SUFFICIENT
FOR MVFR CIGS AND LIGHT RAIN ALONG AND NORTH OF NEBRASKA HIGHWAY
2...POSSIBLY OVER THE KVTN TERMINAL. THE AMOUNT OF MOISTURE
RETURN IS IN QUESTION...THUS DID NOT HAVE HIGH ENOUGH CONFIDENCE TO
MENTION A PREVAILING PRECIPITATION GROUP...BUT WILL INTRODUCE A
PROB30 AT KVTN FROM 09-12Z. OTHERWISE THE MAIN CONCERN TO THE
AVIATION COMMUNITY FOR THE NEXT 24 HOURS WILL BE THE EXPECTED
INCREASE IN WIND SPEEDS BEHIND THE FRONT. MODEL GUIDANCE INDICATES
GUSTS AT OR EXCEEDING 20KTS BEHIND AND SEVERAL HOURS BEHIND THE
FRONT
&&
PREV DISCUSSION... /ISSUED 437 AM CDT THU SEP 6 2012/
UPDATE...
FIRE WEATHER...
THE RFW PRODUCT HAS BEEN UPDATED FOR A WIND SHIFT DEVELOPING
AROUND 18Z PER RAP AND HRRR MODELS. THOSE MODELS ARE CONSOLIDATING
LOW PRESSURE ALONG THE ND/SD BORDER AND SENDING A "COLD" FRONT
INTO NRN NEB. THIS IS ABOUT 3 HOURS FASTER THAN THE OTHER OPERATIONAL
MODELS.
PREV DISCUSSION... /ISSUED 350 AM CDT THU SEP 6 2012/
DISCUSSION...
PRIMARY FORECAST CONCERNS FOR THIS FORECAST ARE FIRE WEATHER
CONCERNS TODAY...HIGHS TODAY...AS WELL AS TEMPERATURES AND RAIN
CHANCES SURROUNDING FRONTAL PASSAGE FRIDAY.
UPPER LEVEL ANALYSIS SHOWED LOW PRESSURE OVER NORTHERN
MANITOBA...WITH ONE SHORTWAVE TROUGH EXTENDING INTO THE GREAT
LAKES...AND A SECOND SHORTWAVE TROUGH EXTENDING INTO THE PACIFIC
NORTHWEST. THIS SECOND SYSTEM IS SHOWING THE STRONGEST ENERGY OVER
SOUTHERN BRITISH COLUMBIA MOVING INTO IDAHO AND MONTANA EARLY THIS
MORNING. ALSO...BROAD RIDGING SEEN ALOFT OVER THE SOUTHERN US.
THIS PATTERN LEADS TO FAIRLY ZONAL/NORTHWEST FLOW INTO THE LOCAL
FORECAST AREA CURRENTLY. THIS FLOW IS BRINGING A GOOD AMOUNT OF
SMOKE INTO THE CENTRAL PLAINS FROM FIRES OVER IDAHO AND WYOMING.
AT THE SURFACE...LOW PRESSURE OBSERVED OVER NORTHWEST SOUTH DAKOTA
WITH A COLD FRONT EXTENDING ACROSS NORTHERN WYOMING AND INTO
WESTERN MONTANA. ALSO...A SURFACE TROUGH WAS SEEN FROM WESTERN
SOUTH DAKOTA INTO THE NEBRASKA PANHANDLE...WITH THE AXIS OF HIGH
PRESSURE FROM NORTHWEST KANSAS INTO NORTHEAST NEBRASKA. UNDER THE
SURFACE HIGH...TEMPERATURES HAD DROPPED INTO THE 40S...WHILE
CLOSER TO THE TROUGH WHERE THE BOUNDARY LAYER HAD STAYED
MIXED...UPPER 60S WERE BEING OBSERVED.
SHORT TERM...TODAY THROUGH SATURDAY NIGHT
THE SHORTWAVE TROUGH OVER IDAHO/MONTANA WILL MOVE SOUTHEAST
ACROSS THE NORTHERN ROCKIES TODAY. THIS WILL KEEP THE FLOW QUITE
FLAT ACROSS THE CENTRAL AND NORTHERN PARTS OF THE COUNTRY...SO
WILL EXPECT TO CONTINUE TO SEE QUITE A BIT OF SMOKE IN THE SKY
THROUGH THE DAY TOMORROW. AS THE UPPER LEVEL SYSTEM MOVES
SOUTH...SO WILL THE COLD FRONT CURRENTLY OVER WYOMING. AHEAD OF
THE FRONT...THE SURFACE TROUGH/DRYLINE OVER THE NEBRASKA PANHANDLE
WILL SURGE EAST BRINGING VERY DRY AIR INTO THE FORECAST AREA. THE
NAM HAS BEEN PERFORMING BEST LATELY IN TERMS OF DEWPOINTS SO FELT
CONFIDENT IN GOING TOWARDS THAT MODEL FOR THE FORECAST TODAY. THIS
WOULD BRING 20 DEGREE DEWPOINTS INTO THE WESTERN PARTS OF THE
FORECAST AREA...WHICH LOOKS REASONABLE AS MUCH OF WYOMING AND
NORTHERN COLORADO ARE OBSERVING VALUES IN THE TEENS CURRENTLY.
THIS DRY AIR WILL HELP TO CREATE DEEP MIXING THIS AFTERNOON...AND
WHEN COMBINED WITH WARM AIR ADVECTION WITH THE HIGH MOVING OFF TO
THE EAST WENT ON THE HIGH END FOR TEMPERATURES TODAY. ALSO...HAVE
BEEN OBSERVING VERY LARGE DIURNAL SWINGS IN TEMPERATURES...SO
ALTHOUGH LOWS WILL BE IN THE 40S FOR SOME PLACES...DON/T SEE A
PROBLEM WITH REACHING THE MID 90S THIS AFTERNOON. PLACES OVER
NORTHWEST NEBRASKA WILL BE A BIT MORE TRICKY FOR HIGH TEMPERATURES
AS THE FRONT WILL PASS THROUGH THESE AREAS THIS AFTERNOON.
ALTHOUGH WILL LIKELY NOT SEE AS HOT OF TEMPERATURES IN THOSE
LOCATIONS...NOT GOING TO SEE THE COLD AIR PUSH INTO NEBRASKA
UNTIL EVENING AND OVERNIGHT SO STILL EXPECTING HIGHS IN THE UPPER
80S. BREEZY WINDS AND ALONG WITH A WINDSHIFT WITH THE
FRONT...COMBINED WITH THE HEAT AND VERY DRY CONDITIONS FIRE
WEATHER CONDITIONS WILL BE OF HIGH CONCERN. SEE DETAILED
DISCUSSION BELOW.
CONTINUED THE SLIGHT CHANCES FOR THUNDERSTORMS IN THE FAR EASTERN
COUNTIES LATER THIS AFTERNOON AND EVENING AS DEVELOPMENT IS
EXPECTED ALONG AND EAST OF THE DRYLINE. PROBABILITIES ARE BEST
EAST OF THE FORECAST AREA...BUT IF THE DRY AIR DOESN/T ADVANCE AS
FAR EAST...THE AREA OF CONCERN WILL SHIFT. ANY STORMS THAT DO
DEVELOP ON THIS LINE WILL HAVE THE POTENTIAL TO BE STRONG TO
SEVERE WITH FAVORABLE SHEAR AND INSTABILITY EXPECTED.
TONIGHT...BREEZY CONDITIONS ARE EXPECTED AS THE FRONT PUSHES
SOUTH. ALTHOUGH COLDER AIR WILL BE PUSHING IN BEHIND THE
FRONT...THE WINDS AND GOOD AMOUNT OF CLOUD COVER WILL PROHIBIT
TEMPERATURES FROM FALLING TOO MUCH. ALSO...THERE WILL BE CHANCES
FOR RAIN TONIGHT. AREAS WITH THE HIGHER CHANCE FOR RAIN WILL BE
OVER NORTHERN NEBRASKA AFTER MIDNIGHT AS STRONGER LIFT WILL BE
OVER THE AREA AT THAT TIME...WITH THE FRONT AND THE UPPER LEVEL
ENERGY PUSHING THROUGH. THESE CHANCES WILL SHIFT SOUTH FRIDAY
MORNING...HOWEVER DYNAMICS DOESN/T LOOK AS GOOD SO ONLY HAVE A
SLIGHT CHANCE THROUGH 18Z ACROSS THE FORECAST AREA. ALTHOUGH
DYNAMICALLY...IT LOOKS FAVORABLE FOR SHOWERS...LOW LEVEL MOISTURE
WILL BE A LIMITING FACTOR. THE NAM IS SHOWING MOISTURE IMPROVING
WITH PRECIPITABLE WATER INCREASING TO NEAR AN INCH ALONG THE
FRONT...BUT DON/T KNOW IF THERE WILL BE THAT MUCH MOISTURE
ADVECTION BETWEEN NOW AND THEN. LATEST KLBF SOUNDING HAD PW OF
0.38 INCHES. CROSS-SECTIONS ALSO SUGGESTING THE COLUMN WILL NEARLY
SATURATE. DON/T WANT TO DISCOUNT THIS...BUT LOOKING AT THIS SYSTEM
OVER MONTANA CURRENTLY...MOST CEILINGS ARE ABOVE 5K FEET. WILL
CONTINUE TO WATCH THE SYSTEM CLOSELY...BUT FEELING IS ANY RAINFALL
WILL BE LIGHT WITH LITTLE ACCUMULATIONS /LESS THAN A TENTH OF AN
INCH/ EXPECTED.
WITH THE CLOUDY SKIES AND COLD AIR MOVING INTO THE AREA BEHIND THE
FRONT...FRIDAY SHOULD BE A MUCH COOLER DAY. LOOKING AT HIGHS ONLY
IN THE UPPER 60S AND 70S. HOWEVER...BIG STORY WILL BE LOWS FRIDAY
NIGHT. WITH HIGH PRESSURE SETTLING IN...SKIES SHOULD CLEAR AND
WINDS ARE EXPECTED TO BECOME LIGHT OR CALM. THESE CONDITIONS WILL
PROMOTE RADIATIONAL COOLING...AND WITH THE DRY AIRMASS IN PLACE
/DEWPOINTS IN THE 30S/...EXPECT A COLD NIGHT ACROSS WESTERN
NEBRASKA. DROPPED LOWS TEMPERATURES...WITH LOCATIONS IN VALLEYS OR
OTHER FAVORED DRAINAGE AREAS FALLING INTO THE 30S. WILL BE CLOSELY
WATCHING THIS IN COMING FORECASTS AS LOWS IN THE 30S COULD MEAN
THE DEVELOPMENT OF FROST IN AREAS.
LOOKING TO SATURDAY...HIGH PRESSURE WILL CONTINUE TO INFLUENCE THE
AREA. HOWEVER...WARM AIR ADVECTION WILL BE ONGOING ALOFT. GOOD
MIXING AND SUNSHINE WILL ALLOW FOR TEMPERATURES TO WARM BACK TO
NEAR NORMAL VALUES AROUND 80 DEGREES.
LONG TERM...SUNDAY THROUGH WEDNESDAY
TEMPERATURES WILL BE ON THE RISE SUNDAY AND MONDAY...WITH
POTENTIAL SHOWING UP FOR ANOTHER HOT DAY ON MONDAY. HAVE LOW 90S
IN THE FORECAST CURRENTLY BUT MAY NEED TO ADJUST THOSE NUMBERS UP
IN COMING FORECASTS. ANOTHER COLD FRONT IS PROJECTED TO MOVE
THROUGH THE FORECAST AREA ON TUESDAY. TIMING IS A BIT PROBLEMATIC
AT THIS TIME...WHICH WILL HAVE IMPACT ON TEMPERATURES FOR TUESDAY.
ANOTHER PUSH OF COLD AIR WILL COME INTO THE AREA BEHIND THIS
FRONT...SO WEDNESDAY IS LOOKING TO BE A DAY WITH HIGHS IN THE 70S.
IN TERMS OF RAINFALL...THE FORECAST REMAINS DRY AS MODELS ARE
SHOWING DRY AIR CONTINUING TO BE DOMINANT SO DON/T HAVE A GOOD
HANDLE IF ANY SHOWERS/STORMS WILL DEVELOP ALONG THE FRONT.
CONSENSUS FROM THE CURRENT MODELS INDICATES THE FRONT WILL PASS BY
DRY FOR THE MOST PART WITH MAYBE A FEW ISOLATED STORMS.
WILL CONTINUE TO KEEP THE FORECAST DRY UNLESS MODELS START SHOWING
BETTER SIGNALS FOR PRECIPITATION DEVELOPMENT.
FIRE WEATHER...
ARF...NMM AND NAM SOLNS SHOW RH FALLING TO BETWEEN 5 AND 7 PERCENT
ACROSS WRN NEB. THE OFFICIAL FORECAST IS FOR 8 TO 10 PERCENT RH AND
WIND GUSTS TO AROUND 30 MPH. THUS A BIG FIRE DAY IS EXPECTED. DPTS
ACROSS WY ARE IN THE TEENS WITH RH AS LOW AS 18 PERCENT AT LANDER
AND RIVERTON AT 07Z.
A RED FLAG WARNING IS IN EFFECT FOR ALL ZONES TODAY.
OTHER OPPORTUNITIES FOR CRITICAL FIRE DANGER COULD DEVELOP SUNDAY
ACROSS THE WRN HIGH PLAINS AS LOW PRESSURE DEEPENS ACROSS THE NRN
HIGH PLAINS. ALSO MONDAY COULD BE A BIG FIRE DAY FOR ALL AREAS AS A
LOW PRESSURE TROF MOVES EAST THROUGH THE CNTL AND NRN PLAINS.
CONCERNS CONTINUE TUESDAY AS DRY AIR WILL BE MOVING SWIFTLY SOUTH
BEHIND A COLD FRONT PROGGED TO MOVE THROUGH MONDAY NIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING UNTIL 10 PM CDT
/9 PM MDT/ THIS EVENING FOR NEZ204-206-208>210-219.
&&
$$
SHORT TERM/EXTENDED...BROOKS
AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS ELKO NV
303 PM PDT THU SEP 6 2012
.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.
&&
$$
97/98/98/97
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
147 PM EDT THU SEP 6 2012
.SYNOPSIS...
WEAK COLD FRONT DISSIPATES THIS EVENING. HIGH PRESSURE FRIDAY. STRONG
COLD FRONT SATURDAY. HIGH PRESSURE SUNDAY INTO THE NEXT WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
11 AM UPDATE...NO SIGNIFICANT CHANGES.
600AM UPDATE...
NO SIGNIFICANT CHANGES MADE WITH THIS UPDATE...JUST TWEAKED
INITIAL SKY GRIDS.
PREVIOUS DISCUSSION BELOW...
SHRA CONT TO INCREASE ACROSS N CARTER AND S GREENUP AS OF
0630Z...WITH NEARLY STATIONARY MOTIONS. BUMPED UP POPS INTO LKLY
NEXT COUPLE HRS ACROSS NE KY COUNTIES. WILL BE MONITORING RAINFALL
AS WELL.
PREVIOUS DISCUSSION BELOW...
SHRA LIGHTING UP ON RADAR AT 06Z ACROSS W ZONES...ASSOCIATED WITH
S/W TROF AND EMBEDDED VORT MAX. RUC TRACKS THIS SLOWLY NE THRU CWA
BY 13Z. HAVE SOME LOW POPS WITH THIS AS IT DOES SO. BACK EDGE OF
CLDS WILL SLOWLY PUSH THRU PORTIONS OF SE OH BY 08Z...TAKING TO
NEAR SUNRISE TO GET INTO CENTRAL WV LOWLANDS. FURTHER COMPLICATING
SKY COVER IS LOW STRATUS THAT IS POISED TO DEVELOP ACROSS ALONG
AND E OF I79 CORRIDOR...BASED ON MODEL PROJECTIONS. THINK THIS MAY
END UP MORE IN MTNS AND S COAL FIELDS. SOME RVR VALLEY FG THROWN
IN AS WELL...ESPECIALLY FOR AREAS THAT MANAGE TO CLR.
WILL TRY TO SCT OUT ANY LOW CLDS BY MID MORNING. WILL LOOK FOR MTN
SHRA AND A FEW TSRA TO DEVELOP WITH HEATING AND WEAK OROGRAPHIC
LIFT. WILL CARRY CHC POPS THERE...TAILING OFF TO SCHC BACK TO I79
CORRIDOR. OTHERWISE...WEAK FRONT DROPPING SE THRU UPR OH VALLEY
LOOKS TO BE DELAYED UNTIL LATE AFTN FOR SE OH ZONES BEFORE BECOMING
RATHER DIFFUSE TONIGHT. HAVE ONLY SCHC POPS WITH THIS AS OVERALL
SETUP LOOKS RATHER MEAGER.
WILL ROLL A TICK OR TWO ABV WARMEST GUIDANCE FOR HIGHS TDY BASED
ON RECENT PERFORMANCE AND NEAR HIGH SIDE OF GUIDANCE FOR LOWS
TONIGHT.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
MODELS HAVE COME INTO DECENT AGREEMENT THROUGHOUT THE PERIOD. MODELS
SHOW HIGH PRESSURE FOR FRIDAY. MESO NAM IS TRYING TO CREATE A FEW
SHOWERS IN THE MOUNTAINS...BUT BELIEVE THAT THE 700 MB AIR IS TOO
DRY. A FAST MOVING COLD FRONT THEN PUSHES THROUGH ON SATURDAY. WILL
FINE TUNE POPS FOR BETTER TIMING. HIGH PRESSURE THEN TAKES OVER
SATURDAY NIGHT INTO THE NEXT WORK WEEK. WILL REMOVE POPS SATURDAY
NIGHT THROUGH SUNDAY NIGHT.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
MADE WHOLESALE CHANGES TO THE LONG TERM FORECAST AS MODELS COMING
INTO BETTER AGREEMENT THAN YESTERDAY...NOW SHOWING OPEN WAVE
SWINGING THROUGH OVER THE WEEKEND...AND A THING OF THE PAST AS WE
HEAD INTO THE WORK WEEK. LINGER CHANCE AND SLIGHT CHANCE POPS
THROUGH SUNDAY...MOVING OUT SUNDAY NIGHT AS THE UPPER TROUGH MOVES
EAST AND OUT TO SEA. THIS WILL PROVIDE A MAINLY DRY FORECAST FOR THE
REST OF THE LONG TERM. DID NOT INCLUDE ANY POPS FOR THE WORK WEEK AT
THIS TIME DUE TO LACKING MOISTURE...BUT WITH NORTHWEST FLOW IT MAY
BE POSSIBLE TO GET A LITTLE SHORTWAVE RIPPLE THAT COULD POP A SHOWER
OR TWO AT SOME POINT. TEMPERATURES WILL START OFF BELOW NORMAL ON
MONDAY...WITH A GRADUAL WARMING TREND TO NEAR NORMAL BY MID TO LATE
WEEK AS UPPER RIDGE MOVES INTO SOUTHERN PLAINS.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
18Z THURSDAY THRU 18Z FRIDAY...
A WEAK DRY COLD WILL DISSIPATE AS IT COMES INTO NORTHERN PORTIONS OF
CWA LATER THIS EVENING. GENERALLY VFR MOSTLY CLEAR THIS PERIOD UNDER
HIGH PRESSURE...EXCEPT FOR IFR/LIFR RIVER AND VALLEY FOG 06Z TO 12Z
FRIDAY...AFFECTING ALL THE MAJOR TERMINALS.
AFTER 12Z FRIDAY...BECOMING VFR MOSTLY CLEAR AROUND 14Z.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY...
FORECAST CONFIDENCE: HIGH.
ALTERNATE SCENARIOS: TIMING OF THE FOG MAY VARY BY AN HOUR OR TWO
LATER TONIGHT.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
CRW CONSISTENCY H H H H H H H H H H H M
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H H H H H H H M L L
PKB CONSISTENCY H H H H H H H H H H M L
CKB CONSISTENCY H H H H H H H H H H H M
AFTER 18Z FRIDAY...
BRIEF IFR POSSIBLE IN THUNDERSTORMS SATURDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30
NEAR TERM...JMV/30
SHORT TERM...RPY
LONG TERM...MZ
AVIATION...JMV
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1243 PM EDT THU SEP 6 2012
.SYNOPSIS...
A WEAK COLD FRONT WILL DRIFT SOUTHEAST ACROSS THE AREA LATER TODAY
INTO TONIGHT. A STRONGER COLD FRONT WILL CROSS THE REGION FRIDAY
NIGHT. HIGH PRESSURE OVER THE PLAINS SUNDAY WILL MOVE UP THE OHIO
VALLEY MONDAY AND TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
ONLY MADE MINOR CHANGES TO THE PREVIOUS FORECAST. LAKE BREEZE AND
WEAK DISSIPATING FRONTAL BOUNDARY WILL BE THE FOCUS FOR ISOLATED
TO SCATTERED THUNDERSTORMS. IF ANY STRONG UPDRAFTS CAN DEVELOP THE
POTENTIAL FOR A SEVERE WIND GUST EXISTS.
PREVIOUS DISCUSSION...
A WEAK COLD FRONT WILL SAG SOUTHWARD INTO THE REGION TODAY.
CONVERGENCE ALONG THE FRONT AND AFTERNOON HEATING SHOULD LEAD TO
SOME ISOLATED TO SCATTERED THUNDERSTORMS. IF ANY STRONG STORMS CAN
DEVELOP THERE WOULD BE A THREAT OF STRONGER WIND GUSTS.
OTHERWISE EXPECT TO SEE SOME AFTERNOON CUMULUS WITH SOME MIDDLE
LEVEL CONVECTIVE DEBRIS. HIGHS THIS AFTERNOON WILL BE IN THE MIDDLE
80S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
LINGERING THREAT FOR EVENING CONVECTION PER PREVIOUS DISCUSSION THEN
AIRMASS SETTLES DOWN DUE TO LOSS OF DAYTIME HEATING AND SLIGHTLY
DRIER AIR DRIFTING SE INTO THE AREA. SOME PATCHY FOG COULD DEVELOP.
DRY PERIOD WILL BE SHORT-LIVED. UPPER TROUGH DIGS SE INTO THE AREA
FOR SAT. A SURFACE WAVE OF LOW PRESSURE IS INDUCED ALONG A COLD
FRONT THAT WILL MOVE THROUGH FRI NIGHT. GOOD DYNAMICS SHOULD LEAD TO
WIDESPREAD SHRA/TSRA SPREADING EAST ACROSS THE CWA STARTING LATER
FRI INTO FRI NIGHT. SOME OF THE RAIN COULD BE LOCALLY HEAVY FRI
NIGHT INTO EARLY SAT. THE THREAT FOR THUNDER SHOULD SHIFT INTO JUST
THE EAST BY SAT MORNING.
COLDER AIR ALOFT WILL LEAD TO LAKE ENHANCEMENT FOR SHRA IN THE
SNOWBELT LATER SAT AND SAT NIGHT. A LITTLE THUNDER COULD OCCUR WITH
THE LAKE EFFECT CONVECTION.
HIGH PRESSURE BEGINS TO BUILD IN FROM THE WEST ON SUN AND THE UPPER
TROUGH AXIS BEGINS TO SHIFT EAST OF THE AREA DURING THE AFTERNOON.
THIS SHOULD KEEP THE SHRA THREAT LIMITED TO MOSTLY JUST THE EAST.
A LINGERING SHRA OR TWO COULD HANG AROUND OVER THE SNOWBELT SUN
NIGHT...OTHERWISE THE REST OF THE AREA SHOULD BE DRY AS DRIER AIR
AND SUBSIDENCE TAKE CONTROL.
NOTICEABLY COOLER TEMPS WILL ARRIVE FOR SAT AND CONTINUE SUN WITH
HIGHS MOSTLY IN THE 60S. LOWS BY SUN NIGHT SHOULD MAINLY BE IN A 50
TO 55 RANGE AS CLOUDS BEGIN TO BREAK UP.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
A MODERATING TREND IN TEMPERATURES FOR THE PERIOD. HIGH PRESSURE
WILL BE OVER THE AREA ON MONDAY AND THEN IT WILL MOVE EAST AND THE
SOUTHERLY FLOW WILL ALLOW TEMPERATURES TO WARM BACK TO NEAR NORMAL
LEVELS. DRY FOR THE PERIOD. EVEN THOUGH ON MONDAY THE LAKE AND 850
MB TEMPERATURE DIFFERENCE WILL BE NEAR 15C THE FLOW WILL BE SO WEAK
THAT JUST SOME CLOUDS WILL BE AROUND AND NO SHOWERS. A COLD FRONT
WILL BE MOVING THROUGH WEDNESDAY NIGHT BUT AT THIS TIME THAT MAY BE
DRY.
&&
.AVIATION /12Z THURSDAY THROUGH TUESDAY/...
AREAS OF FOG AND ISOLATED STRATUS WILL BURN OFF AFTER SUNRISE.
TODAYS WEATHER WILL BE CAUSED BY A COLD FRONT THAT WILL MOVE
THROUGH. AT 11Z THE COLD FRONT WAS LOCATED FROM WESTERN LOWER
MICHIGAN TO EAST OF CHICAGO TO NORTHERN MISSOURI. SOME CLOUDS WERE
ALONG IT. THE FRONT WILL MOVE THROUGH THE REGION MAINLY DURING THE
AFTERNOON. HOWEVER...SOME SHOWERS COULD DEVELOP OVER NORTHWEST
OHIO THIS MORNING. THE BEST CHANCE FOR THUNDER WILL BE FROM CLE
AND MFD SOUTHEAST. THE HRRR MODEL SEEMS TO HAVE A GOOD HANDLE ON
THINGS. THE BEST CHANCE TO HAVE THUNDER AT A TAF SITE WILL BE CAK
AND YNG. SINCE THE FRONT WILL BE THE CAUSE OF THE THUNDERSTORMS
THEY SHOULD BE IN A LINE WITH SOME ISOLATED CONVECTION AHEAD OF
IT.
CLOUDS WILL DECREASE TONIGHT. THE MODELS ARE VERY SLOW IN
DECREASING THE MOISTURE...THIS MAY BE TOO SLOW BASED ON WHAT IS
GOING ON NOW UPSTREAM. SOMETIMES AFTER A FRONTAL PASSAGE MVFR
CEILINGS DEVELOP. IN THIS CASE THE WIND SHIFT IS BRIEF. THE MODELS
DO HINT AT SOME MOISTURE NEAR ERIE...SO KEPT SOME SCATTERED
LOW CLOUDS IN THAT AREA. OTHERWISE THE AIRMASS IS TRYING TO DRY
OUT...SO NOT EXPECTING FOG AT THE TAF SITES...HOWEVER...PATCHY
MVFR FOG WILL OCCUR ELSEWHERE.
.OUTLOOK...NON VFR POSSIBLE FRIDAY NIGHT INTO SUNDAY.
&&
.MARINE...
A WEAK COLD FRONT WILL BE MOVING ACROSS THE LAKE TODAY. A SOUTHWEST
TO WEST FLOW AHEAD OF THE FRONT AND THEN A LIGHT NORTHWEST BEHIND
THE FRONT. NOT EXPECTING CONDITIONS TO MEET SMALL CRAFT ADVISORY
CONDITIONS. A FEW THUNDERSTORMS ON THE LAKE COULD BE STRONG LATER
TODAY. HIGH PRESSURE WILL MOVE ACROSS THE LAKE TONIGHT.
FRIDAY NIGHT THROUGH SUNDAY COULD BE INTERESTING ON THE LAKE. A COLD
FRONT WILL MOVE ACROSS THE LAKE FRIDAY NIGHT WITH A NORTHWEST TO
NORTH FLOW FOR THE WHOLE WEEKEND. THE WINDS COULD BE STRONG ENOUGH
ESPECIALLY LATE FRIDAY NIGHT INTO SATURDAY TO PROMPT A SMALL CRAFT
ADVISORY ESPECIALLY ON THE EAST END OF THE LAKE. DETAILS ARE NOT
CLEAR AT THIS TIME. THE LAKE AND 850 MB TEMPERATURE DIFFERENCE WILL
BE AROUND 15C FOR MOST OF SATURDAY AND SUNDAY AND WITH PLENTY OF
MOISTURE SOME COLD AIR WATERSPOUTS AND FUNNELS ARE QUITE POSSIBLE.
HIGH PRESSURE WILL MOVE ACROSS THE LAKE MONDAY AND THEN A SOUTHERLY
FLOW WILL DEVELOP FOR TUESDAY THROUGH WEDNESDAY. NOT EXPECTING SMALL
CRAFT ADVISORY CRITERIA DURING THIS PERIOD.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ADAMS
NEAR TERM...MULLEN
SHORT TERM...ADAMS
LONG TERM...KIELTYKA
AVIATION...KIELTYKA
MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
448 PM EDT THU SEP 6 2012
.SYNOPSIS...
A WEAK COLD FRONT WILL MOVE SLOWLY ACROSS THE STATE TODAY AND
TONIGHT. AN UPPER TROUGH WILL FORM OVER THE GREAT LAKES AND
MIDWEST AND AMPLIFY AS IT APPROACHES PENNSYLVANIA...BRINGING
UNSETTLED WEATHER INTO THE WEEKEND. HIGH PRESSURE WILL BUILD INTO
THE AREA LATE MONDAY...BRINGING IN COOLER TEMPERATURES...BEFORE
MOVING OFF THE COAST LATER IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
MINOR UPDATE TO EDGE POPS UP ACROSS THE NORTH. STORMS HAVE
FORMED AHEAD OF COLD FRONT AND ON ALLEGANY FRONT.
EARLIER DISCUSSION BELOW.
A WEAK COLD FRONT ENTERING WESTERN PA WILL BE THE FOCUS FOR
SOME SCATTERED CONVECTION THIS AFTERNOON. BEHIND THE DEPARTING
SHORTWAVE CURRENTLY BRINGING SOME CLOUDS TO SERN ZONES...SATELLITE
AND RUC DATA SUPPORT A MSUNNY DAY ACROSS THE NWRN 2/3 OR SO OF THE
FCST AREA...WITH INCREASING SUNSHINE FOR THE AFTERNOON ACROSS THE
SE PART OF THE CWA.
THE SUNSHINE AND MDL 8H TEMPS ARND 17C WILL ALLOW TEMPS TO CLIMB
QUICKLY INTO THE 80S BY AFTN...WITH THE LOWER SUSQ VALLEY NEARING
90F.
RUC INDICATES STEEPENING MID LEVEL LAPSE RATES ALREADY DEVELOPING
OVER WESTERN PA IN RESPONSE TO STRONG HEATING AND SLOWLY FALLING
MID LEVEL TAMPS AND HEIGHTS. SPC RAP SHOWS CAPES EXCEEDING 3000J
OVER WRN PA. MOISTURE CONVERGENCE IS WEAK HOWEVER AND VIZ SHOTS
ARE JUST STARTING TO SHOW THE DEVELOPMENT OF A CU FIELD BACK OVER
THE LOWER LAKES. THIS SHOULD CONTINUE TO DEVELOP AS THE DAY HEATS
UP...WITH THE BEST CHANCES FOR STORMS BEING OVER MY NWRN
COUNTIES.
THE INSTABILITY COMBINED WITH SOME MODEST WIND SHEAR COULD BE
ENOUGH TO SUPPORT ISOLATED STRONG WIND GUSTS IN SOME OF THE
THUNDERSTORMS.
ACTIVITY SHOULD WANE AFTER THE LOSS OF HEATING...LEADING TO A
MAINLY DRY OVERNIGHT WITH MORE OF THE KIND OF LATE NIGHT FOG AND
LOW CLOUDS WE HAVE SEEN OVER THE LAST FEW NIGHTS. IT WILL REMAIN
QUITE MILD...IN THE 60S.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
A WEAK HIGH WILL BUILD INTO THE AREA BY LATE FRIDAY AS THE
FRONTAL BOUNDARY LIFTS BACK NORTH AS A WARM FRONT INTO NEW YORK
STATE. SW FLOW AT THE SFC AND ALOFT WILL MAINTAIN VERY WARM AND
SOMEWHAT HUMID CONDITIONS...ESP IN THE SOUTH WHERE TEMPS WILL TOP
OUT IN THE U80S TO LOWER 90S WITH SFC DEWPOINTS IN THE U60S TO
AROUND 70F.
HIGH TEMPS IN ALL AREAS FRIDAY WILL ONCE AGAIN BE 10-12F ABOVE
NORMAL.
GFS AND THE NEW NAM KEEP US DRY THRU THE DAY FRIDAY. THIS LOOKS
MORE REASONABLE THAN THE SMALL CHC POPS OF THE 09Z SREF.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
CLOUDS THICKEN UP WITH SHRA/TSRA WELL AFTER MIDNIGHT ACROSS THE
ALLEGHENY PLATEAU OF NRN AND WRN PENN.
LOW LEVEL WIND SHEAR COULD IMPACT AVIATION AND BE FELT ACRS THE
HIGHER TERRAIN FRIDAY NIGHT INTO SATURDAY...AS THE SSW FLOW IN THE
1-2 KFT AGL LAYER STRENGTHENS TO 35-40 KTS.
DEEP LOW FCST TO DRAG A WARM FRONT...THEN A COLD FRONT ACROSS THE
AREA ON SAT. MODELS DO NOT CLOSE LOW OFF NOW...BUT STILL LOOKS WET.
SOME CHC OF STRONG TO PERHAPS SEVERE STORMS ACROSS THE EAST LATE.
LESS CHC FOR WIDESPREAD HEAVY RAIN NOW...AS SYSTEM DOES NOT CLOSE
OFF AND GO NEGATIVE. STILL WILL BE WET FOR MUCH OF THE DAY.
RATHER STRONG UPPER LVL LOW MOVING ACROSS THE REGION ON SUNDAY...
THUS EXPECT CU TO DEVELOP FAST...LIMIT MAX TEMPS...AND RESULT IN
SHOWERS AND STORMS. BASED ON THIS...LEFT CHC POPS IN...MORE IN
LINE WITH THE GFS...THAN THE NAM MODEL.
ON THE COOL SIDE FOR SAT ACROSS THE FAR WEST...AND THE AREA
SUNDAY INTO TUE AM...BUT NOTHING ABNORMAL FOR LATE AUG...
EARLY SEPT. TUE AM COULD BE AS COOL ACROSS THE SE...AS OTHER
AREAS.
MINOR ADJUSTMENTS TO TEMPS. TOOK OUT SHOWERS FOR SUNDAY
NIGHT.
TUE AND WED LOOK DRY WITH HIGH PRESSURE OVER WV.
A SW FLOW FOR THU...BUT STILL DRY...AS THE HIGH MOVES EAST.
&&
.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
STILL SHOWING MDT/LNS HANGING DOGGEDLY ONTO CIGS AROUND 3000```BUT
I EXPECT THESE TO LIFT QUICKLY SO HAVE STARTED THE NEW TAF PACKAGE
OFF AS VFR AT ALL SITES.
THE REST OF THE AFTERNOON WILL SEE SCATTERED CONVECTION BECOMING
THE THREAT WITH LOCALIZED RESTRICTIONS IN THE SHOWERS/STORMS AS
WELL AS THE POTENTIAL FOR ISOLATED STRONG WIND GUSTS IN STRONGER
THUNDERSTORMS. MOST LIKLEY AREAS TO SEE THIS SHOULD BE ALONG
NY...PA BORDER.
EXPECT MORE LATE NIGHT FOG AND LOW CLOUDS TONIGHT.
OUTLOOK...
FRI...MAINLY VFR AFTER EARLY MORNING FOG/LOW CLOUD RESTRICTIONS.
SAT...DETERIORATING CONDITIONS WITH THE APPROACH OF A WAVE OF LOW
PRESSURE AND COLD FRONT.
SUN...MVFR EARLY...IMPROVING DURING THE DAY.
MON-TUE...NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE/MARTIN
SHORT TERM...LA CORTE
LONG TERM...MARTIN
AVIATION...LA CORTE
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
344 PM EDT THU SEP 6 2012
.SYNOPSIS...
A WEAK COLD FRONT WILL MOVE SLOWLY ACROSS THE STATE TODAY AND
TONIGHT. AN UPPER TROUGH WILL FORM OVER THE GREAT LAKES AND
MIDWEST AND AMPLIFY AS IT APPROACHES PENNSYLVANIA...BRINGING
UNSETTLED WEATHER INTO THE WEEKEND. HIGH PRESSURE WILL BUILD INTO
THE AREA LATE MONDAY...BRINGING IN COOLER TEMPERATURES...BEFORE
MOVING OFF THE COAST LATER IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
A WEAK COLD FRONT ENTERING WESTERN PA WILL BE THE FOCUS FOR SOME
SCATTERED CONVECTION THIS AFTERNOON. BEHIND THE DEPARTING
SHORTWAVE CURRENTLY BRINGING SOME CLOUDS TO SERN ZONES...SATELLITE
AND RUC DATA SUPPORT A MSUNNY DAY ACROSS THE NWRN 2/3 OR SO OF
THE FCST AREA...WITH INCREASING SUNSHINE FOR THE AFTERNOON ACROSS
THE SE PART OF THE CWA.
THE SUNSHINE AND MDL 8H TEMPS ARND 17C WILL ALLOW TEMPS TO CLIMB
QUICKLY INTO THE 80S BY AFTN...WITH THE LOWER SUSQ VALLEY NEARING
90F.
RUC INDICATES STEEPENING MID LEVEL LAPSE RATES ALREADY DEVELOPING
OVER WESTERN PA IN RESPONSE TO STRONG HEATING AND SLOWLY FALLING
MID LEVEL TAMPS AND HEIGHTS. SPC RAP SHOWS CAPES EXCEEDING 3000J
OVER WRN PA. MOISTURE CONVERGENCE IS WEAK HOWEVER AND VIZ SHOTS
ARE JUST STARTING TO SHOW THE DEVELOPMENT OF A CU FIELD BACK OVER
THE LOWER LAKES. THIS SHOULD CONTINUE TO DEVELOP AS THE DAY HEATS
UP...WITH THE BEST CHANCES FOR STORMS BEING OVER MY NWRN
COUNTIES.
THE INSTABILITY COMBINED WITH SOME MODEST WIND SHEAR COULD BE
ENOUGH TO SUPPORT ISOLATED STRONG WIND GUSTS IN SOME OF THE
THUNDERSTORMS.
ACTIVITY SHOULD WANE AFTER THE LOSS OF HEATING...LEADING TO A
MAINLY DRY OVERNIGHT WITH MORE OF THE KIND OF LATE NIGHT FOG AND
LOW CLOUDS WE HAVE SEEN OVER THE LAST FEW NIGHTS. IT WILL REMAIN
QUITE MILD...IN THE 60S.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
A WEAK HIGH WILL BUILD INTO THE AREA BY LATE FRIDAY AS THE
FRONTAL BOUNDARY LIFTS BACK NORTH AS A WARM FRONT INTO NEW YORK
STATE. SW FLOW AT THE SFC AND ALOFT WILL MAINTAIN VERY WARM AND
SOMEWHAT HUMID CONDITIONS...ESP IN THE SOUTH WHERE TEMPS WILL TOP
OUT IN THE U80S TO LOWER 90S WITH SFC DEWPOINTS IN THE U60S TO
AROUND 70F.
HIGH TEMPS IN ALL AREAS FRIDAY WILL ONCE AGAIN BE 10-12F ABOVE
NORMAL.
GFS AND THE NEW NAM KEEP US DRY THRU THE DAY FRIDAY. THIS LOOKS
MORE REASONABLE THAN THE SMALL CHC POPS OF THE 09Z SREF.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
CLOUDS THICKEN UP WITH SHRA/TSRA WELL AFTER MIDNIGHT ACROSS THE
ALLEGHENY PLATEAU OF NRN AND WRN PENN.
LOW LEVEL WIND SHEAR COULD IMPACT AVIATION AND BE FELT ACRS THE
HIGHER TERRAIN FRIDAY NIGHT INTO SATURDAY...AS THE SSW FLOW IN THE
1-2 KFT AGL LAYER STRENGTHENS TO 35-40 KTS.
DEEP LOW FCST TO DRAG A WARM FRONT...THEN A COLD FRONT ACROSS THE
AREA ON SAT. MODELS DO NOT CLOSE LOW OFF NOW...BUT STILL LOOKS WET.
SOME CHC OF STRONG TO PERHAPS SEVERE STORMS ACROSS THE EAST LATE.
LESS CHC FOR WIDESPREAD HEAVY RAIN NOW...AS SYSTEM DOES NOT CLOSE
OFF AND GO NEGATIVE. STILL WILL BE WET FOR MUCH OF THE DAY.
RATHER STRONG UPPER LVL LOW MOVING ACROSS THE REGION ON SUNDAY...
THUS EXPECT CU TO DEVELOP FAST...LIMIT MAX TEMPS...AND RESULT IN
SHOWERS AND STORMS. BASED ON THIS...LEFT CHC POPS IN...MORE IN
LINE WITH THE GFS...THAN THE NAM MODEL.
ON THE COOL SIDE FOR SAT ACROSS THE FAR WEST...AND THE AREA
SUNDAY INTO TUE AM...BUT NOTHING ABNORMAL FOR LATE AUG...
EARLY SEPT. TUE AM COULD BE AS COOL ACROSS THE SE...AS OTHER
AREAS.
MINOR ADJUSTMENTS TO TEMPS. TOOK OUT SHOWERS FOR SUNDAY
NIGHT.
TUE AND WED LOOK DRY WITH HIGH PRESSURE OVER WV.
A SW FLOW FOR THU...BUT STILL DRY...AS THE HIGH MOVES EAST.
&&
.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
STILL SHOWING MDT/LNS HANGING DOGGEDLY ONTO CIGS AROUND 3000```BUT
I EXPECT THESE TO LIFT QUICKLY SO HAVE STARTED THE NEW TAF PACKAGE
OFF AS VFR AT ALL SITES.
THE REST OF THE AFTERNOON WILL SEE SCATTERED CONVECTION BECOMING
THE THREAT WITH LOCALIZED RESTRICTIONS IN THE SHOWERS/STORMS AS
WELL AS THE POTENTIAL FOR ISOLATED STRONG WIND GUSTS IN STRONGER
THUNDERSTORMS. MOST LIKLEY AREAS TO SEE THIS SHOULD BE ALONG
NY...PA BORDER.
EXPECT MORE LATE NIGHT FOG AND LOW CLOUDS TONIGHT.
OUTLOOK...
FRI...MAINLY VFR AFTER EARLY MORNING FOG/LOW CLOUD RESTRICTIONS.
SAT...DETERIORATING CONDITIONS WITH THE APPROACH OF A WAVE OF LOW
PRESSURE AND COLD FRONT.
SUN...MVFR EARLY...IMPROVING DURING THE DAY.
MON-TUE...NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...MARTIN
AVIATION...LA CORTE
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
145 PM EDT THU SEP 6 2012
.SYNOPSIS...
A WEAK COLD FRONT WILL MOVE SLOWLY ACROSS THE STATE TODAY AND
TONIGHT. AN UPPER TROUGH WILL FORM OVER THE GREAT LAKES AND
MIDWEST AND AMPLIFY AS IT APPROACHES PENNSYLVANIA...BRINGING
UNSETTLED WEATHER INTO THE WEEKEND. HIGH PRESSURE WILL BUILD INTO
THE AREA LATE MONDAY...BRINGING IN COOLER TEMPERATURES...BEFORE
MOVING OFF THE COAST LATER IN THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
A WEAK COLD FRONT ENTERING WESTERN PA WILL BE THE FOCUS FOR SOME
SCATTERED CONVECTION THIS AFTERNOON. BEHIND THE DEPARTING
SHORTWAVE CURRENTLY BRINGING SOME CLOUDS TO SERN ZONES...SATELLITE
AND RUC DATA SUPPORT A MSUNNY DAY ACROSS THE NWRN 2/3 OR SO OF
THE FCST AREA...WITH INCREASING SUNSHINE FOR THE AFTERNOON ACROSS
THE SE PART OF THE CWA.
THE SUNSHINE AND MDL 8H TEMPS ARND 17C WILL ALLOW TEMPS TO CLIMB
QUICKLY INTO THE 80S BY AFTN...WITH THE LOWER SUSQ VALLEY NEARING
90F.
RUC INDICATES STEEPENING MID LEVEL LAPSE RATES ALREADY DEVELOPING
OVER WESTERN PA IN RESPONSE TO STRONG HEATING AND SLOWLY FALLING
MID LEVEL TAMPS AND HEIGHTS. SPC RAP SHOWS CAPES EXCEEDING 3000J
OVER WRN PA. MOISTURE CONVERGENCE IS WEAK HOWEVER AND VIZ SHOTS
ARE JUST STARTING TO SHOW THE DEVELOPMENT OF A CU FIELD BACK OVER
THE LOWER LAKES. THIS SHOULD CONTINUE TO DEVELOP AS THE DAY HEATS
UP...WITH THE BEST CHANCES FOR STORMS BEING OVER MY NWRN
COUNTIES.
THE INSTABILITY COMBINED WITH SOME MODEST WIND SHEAR COULD BE
ENOUGH TO SUPPORT ISOLATED STRONG WIND GUSTS IN SOME OF THE
THUNDERSTORMS.
ACTIVITY SHOULD WANE AFTER THE LOSS OF HEATING...LEADING TO A
MAINLY DRY OVERNIGHT WITH MORE OF THE KIND OF LATE NIGHT FOG AND
LOW CLOUDS WE HAVE SEEN OVER THE LAST FEW NIGHTS. IT WILL REMAIN
QUITE MILD...IN THE 60S.
&&
.SHORT TERM /FRIDAY/...
A WEAK HIGH WILL BUILD INTO THE AREA BY LATE FRIDAY AS THE
FRONTAL BOUNDARY LIFTS BACK NORTH AS A WARM FRONT INTO NEW YORK
STATE. SW FLOW AT THE SFC AND ALOFT WILL MAINTAIN VERY WARM AND
SOMEWHAT HUMID CONDITIONS...ESP IN THE SOUTH WHERE TEMPS WILL TOP
OUT IN THE U80S TO LOWER 90S WITH SFC DEWPOINTS IN THE U60S TO
AROUND 70F.
HIGH TEMPS IN ALL AREAS FRIDAY WILL ONCE AGAIN BE 10-12F ABOVE
NORMAL.
GFS AND THE NEW NAM KEEP US DRY THRU THE DAY FRIDAY. THIS LOOKS
MORE REASONABLE THAN THE SMALL CHC POPS OF THE 09Z SREF.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
CLOUDS THICKEN UP WITH SHRA/TSRA BECOMING LIKELY WELL AFTER MIDNIGHT
ACROSS THE ALLEGHENY PLATEAU OF NRN AND WRN PENN.
LOW LEVEL WIND SHEAR COULD IMPACT AVIATION AND BE FELT ACRS THE
HIGHER TERRAIN FRIDAY NIGHT INTO SATURDAY...AS THE SSW FLOW IN THE
1-2 KFT AGL LAYER STRENGTHENS TO 35-40 KTS.
DEEP LOW FCST TO DRAG A WARM FRONT...THEN A COLD FRONT ACROSS THE
AREA ON SAT. MODELS DO NOT CLOSE LOW OFF NOW...BUT STILL LOOKS WET.
SOME CHC OF STRONG TO PERHAPS SEVERE STORMS ACROSS THE EAST LATE.
LESS CHC FOR WIDESPREAD HEAVY RAIN NOW...AS SYSTEM DOES NOT CLOSE
OFF AND GO NEGATIVE. STILL WILL BE WET FOR MUCH OF THE DAY.
RATHER STRONG UPPER LVL LOW MOVING ACROSS THE REGION ON SUNDAY...
THUS EXPECT CU TO DEVELOP FAST...LIMIT MAX TEMPS...AND RESULT IN
SHOWERS AND STORMS. DID LOWER TEMPS A TAD FOR SOME PERIODS AFTER
SATURDAY.
WITH THE UPPER LVL LOW MOVING OUT FASTER NOW...SHOULD BE DRY ON
MONDAY.
TUE AND WED LOOK DRY WITH HIGH PRESSURE OVER WV.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
STILL SHOWING MDT/LNS HANGING DOGGEDLY ONTO CIGS AROUND 3000```BUT
I EXPECT THESE TO LIFT QUICKLY SO HAVE STARTED THE NEW TAF PACKAGE
OFF AS VFR AT ALL SITES.
THE REST OF THE AFTERNOON WILL SEE SCATTERED CONVECTION BECOMING
THE THREAT WITH LOCALIZED RESTRICTIONS IN THE SHOWERS/STORMS AS
WELL AS THE POTENTIAL FOR ISOLATED STRONG WIND GUSTS IN STRONGER
THUNDERSTORMS. MOST LIKLEY AREAS TO SEE THIS SHOULD BE ALONG
NY...PA BORDER.
EXPECT MORE LATE NIGHT FOG AND LOW CLOUDS TONIGHT.
OUTLOOK...
FRI...MAINLY VFR AFTER EARLY MORNING FOG/LOW CLOUD RESTRICTIONS.
SAT...DETERIORATING CONDITIONS WITH THE APPROACH OF A WAVE OF LOW
PRESSURE AND COLD FRONT.
SUN...MVFR EARLY...IMPROVING DURING THE DAY.
MON-TUE...NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...LAMBERT/MARTIN
AVIATION...LA CORTE
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
351 PM EDT THU SEP 6 2012
.SYNOPSIS...
SLIGHTLY DRIER AIR WILL PREVAIL ACROSS OUR REGION ON FRIDAY UNDER
WEAK HIGH PRESSURE. A STRONG COLD FRONT WILL MOVE ACROSS THE
AREA SATURDAY AND SATURDAY NIGHT WITH DRY AIR OVERSPREADING THE
REGION ON SUNDAY. DRY HIGH PRESSURE WILL SETTLE OVER THE REGION FOR
MUCH OF NEXT WEEK.
&&
.NEAR TERM /THROUGH FRIDAY/...
430 PM EDT UPDATE...THE BIGGEST CHANGE FOR THE UPDATE INCLUDED
ADDING A NUMEROUS -SHRA/TS AREA ACROSS THE EASTERN UPSTATE AND INTO
THE NC PIEDMONT AROUND KCLT...PER THE LATEST 88D TRENDS AND SFC
CONVERGENCE FIELDS. THERE COULD BE SOME TRAINING HYDRO ISSUES LATER
ON...DEPENDIN ON TRANSLATION OF THE UPPER TROF EASTWARD. SKY COVER
WAS ADJUSTED USING THE LATEST VSBL LOOP AND INTERPOLATED HR/LY
THROUGH THE EVENING. MINOR CHANGES WERE MADE TO TEMPS/TDS...MAINLY
ACROSS THE EASTERN PIEDMONT WHERE CONVECTIVE CLOUD COVER HAS KEPT
HR/LY VALUES LOWER THAN FORECASTED.
THE 16 UTC RAP AND WATER VAPOR IMAGERY CONTINUE TO INDICATE A WELL
DEFINED SHORT WAVE TROF SLOWLY PROGRESSING ACROSS THE NC MTNS. AHEAD
OF THE TROUGH...A STOUT AREA OF PVA EXITS OVER THE FOOTHILLS AND
WESTERN PIEDMONT. THE WAVE WILL CONTINUE TO SLOWLY TRANSLATE TO THE
ESE OVER THE NEXT SEVERAL HOURS. DEWPOINTS ARE QUITE HIGH OVER THE
WESTERN CAROLINAS AND NE GA...AND NOW THAT TEMPS HAVE WARMED INTO
THE L-M80S...SBCAPE VALUES HAVE RISEN TO 2000 J/KG OR HIGH IN MANY
AREAS. THIS HAS RESULTED IN THE DEVELOPMENT OF SHRA/TSTMS OVER THE
ERN UPSTATE AND SRN NC PIEDMONT. THE ACTIVITY SHOULD INCREASE IN
COVERAGE OVER THE NEXT COUPLE HOURS...THEN MOVE EAST OF THE REGION
BY EARLY EVENING. THE LATEST SPC MESOANALYSIS SHOWS A DCAPE MINIMUM
ACROSS THE REGION. FREEZING LEVELS ARE ALSO OVER 15KFT.
THEREFORE...NEITHER DAMAGING WINDS OR NOR HAIL WILL BE MUCH OF A
THREAT WITH STORMS THIS AFTN. THE STORMS SHOULD NOT BECOME VERY
ORGANIZED AND 30 TO 40 PERCENT COVERAGE...MAINLY OVER THE ERN
ZONES...STILL LOOKS REASONABLE. THE EXCEPTION TO THIS COULD BE THE
SRN NC PIEDMONT WHERE THE WAVE IS ALSO RESULTING IS INCREASED LLVL
CONVERGENCE.
LATE TONIGHT WIDESPREAD DENSE VALLEY FOG IS EXPECTED OVER THE NC
MTNS. WITH THE MID-LEVELS DRY OUT...FOR SHOULD ALSO BE A LITTLE MORE
WIDESPREAD ACROSS THE FOOTHILLS AND PIEDMONT...PARTICULARLY ALONG
THE LARGER RIVER VALLEYS.
SLIGHTLY DRIER AIR WILL WORK INTO THE REGION TOMORROW. A SHORT WAVE
RIDGE WILL ALSO SLOWLY TRANSLATE ACROSS THE FA. WITH MUCH DRIER AIR
ALOFT AND WARM H7 TEMPS CONVECTION WILL HAVE DIFFICULTLY DEVELOPING
TOMORROW AND I HAVE A DRY FORECAST FOR THE FOOTHILLS AND PIEDMONT.
ISOLATED STORMS ARE POSSIBLE OVER THE MTNS...PARTICULARLY OVER THE
HIGHER ELEVATIONS. WITH DRIER AIR AND LIGHT DOWNSLOPE
FLOW...TEMPERATURES WILL RISE INTO THE L90S ACROSS MUCH OF FOOTHILLS
AND PIEDMONT.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
COLD FROPA AND ASSOCIATED PRECIPITATION ARE THE BIG CONCERN FOR
FRIDAY NIGHT AND SATURDAY. 850MB WINDS WERE STRONGER ON 00Z NAM THAN
ON 06Z GFS...WHICH LED THE NAM TO PRODUCE STRONGER THETA-E ADVECTION
AND MOISTURE TRANSPORT AHEAD OF THE FRONT. 12Z NAM HAS WEAKER WINDS
MORE IN LINE WITH THE GFS AND ITS MOISTURE FIELDS REFLECT THE WEAKER
ADVECTION. DECENT AGREEMENT BETWEEN MODELS IN TIMING OF
FROPA...WHICH APPEARS TO OCCUR BETWEEN 12Z AND 18Z. PRECIPITABLE
WATER VALUES INCREASE AS THE FRONT ENTERS THE PIEDMONT...BUT THE
VALUES OVER THE MOUNTAINS ARE MORE EXTREME WITH RESPECT TO
CLIMATOLOGY. IF THE DYNAMICS ALONG THE FRONT WERE MORE IMPRESSIVE I
WOULD BE INCLINED TO GO WITH HIGHER QPF...BUT KEPT IT IN CHECK FOR
NOW.
WITH THE FRONT MOVING THROUGH EARLY IN THE DAY...INSTABILITY WILL BE
LIMITED...BUT FORECAST SOUNDINGS INDICATE ENOUGH CAPE TO WARRANT A
THUNDER MENTION. HOWEVER THE BETTER CHANCES FOR THUNDER WILL BE OVER
THE SC PIEDMONT ZONES DURING THE AFTERNOON AS THAT AREA WILL HAVE
MORE TIME TO DESTABILIZE.
COLD ADVECTION AND SUBSIDENCE SET IN QUICKLY BEHIND THE FRONT AND
MODELS AGREE PRECIP SHOULD END BY LATE SATURDAY EVENING. COULD SEE
SOME STRONG GAP WINDS IN THE MOUNTAIN VALLEYS OVERNIGHT SATURDAY
NIGHT GIVEN STRONG WINDS IN 1000-3000 FT LAYER AND WEAK INVERSION
PROFILE EXPECTED WITH PARTLY CLOUDY SKIES STILL IN PLACE.
SUNDAY LOOKS TO BE REFRESHINGLY COOLER AND LESS HUMID
WITH HIGHS IN THE MID 70S OVER THE MOUNTAINS TO THE LOWER 80S OVER
THE PIEDMONT. ONE ITEM OF NOTE IS THAT THE 00Z EC DEVELOPS THE
TROUGH INTO A CUTOFF UPPER LOW OVER THE NORTHEAST CONUS...WITH A
WEAK LOBE OF VORTICITY REACHING THE MOUNTAINS LATE SUNDAY. HOWEVER
THE MODEL DOES NOT PRODUCE ANY PRECIP AND THE WHOLE TROUGH IS LONG
GONE ON THE GFS AT THIS TIME ANYWAY...SO STILL FEEL PRETTY CONFIDENT
WITH DRY FORECAST SUNDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 200 PM EDT THURSDAY...BY 00Z MONDAY ALL MODELS ARE INDICATING
THAT DRY AIR WILL BE WELL ESTABLISHED AS THE AXIS OF THE UPPER
TROUGH WILL BE OVER OUR AREA AND MOVING EAST. COOLER CANADIAN HIGH
PRESSURE WILL BE MOVING FROM THE MISSISSIPPI VALLEY SUNDAY EVENING
TO BE POSITIONED OVER WEST VIRGINIA BY AROUND 00Z TUESDAY. HIGH
PRESSURE WILL SLOWLY SLIDE OFF THE EAST COAST IN MID WEEK AS THE
NEXT COLD FRONT APPROACHES FROM THE NORTHWEST. HPC HAS THE FRONT
OVER THE OHIO RIVER THURSDAY MORNING AS THAT POSITION MORE CLOSELY
FOLLOWS THE ECMWF WHICH HAS A MUCH MORE SHALLOW TROUGH CROSSING THE
GREAT LAKES AND HAS VERY LITTLE MOISTURE. THE GFS IS MUCH SLOWER
WITH A SHARPER UPPER TROUGH AND DEEPER MOISTURE. THEREFORE...ONLY
INCREASING THE CLOUDS A BIT OVER THE MOUNTAINS AT THE END OF THE
CURRENT FORECAST WHICH AT THIS POINT IS THURSDAY NIGHT.
TEMPERATURES WILL BE A FEW DEGREES BELOW NORMAL DURING THE FIRST
HALF OF THE WEEK AND WARMING TO JUST BELOW NORMAL BY THURSDAY.
&&
.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
AT KCLT...SCT SHRA ARE BEGINNING TO DEVELOP OVER THE UPSTATE AND WRN
NC PIEDMONT ALONG A LINE FROM ABOUT 20 MILES NW OF THE AIRFIELD TO
40 MILES TO IT/S SOUTHWEST. WITH AN UNSTABLE ATMOSPHERE AND A WELL
DEFINED UPPER TROUGH APPROACHING...THE SHRA SHOULD GROW INTO TSTMS
AND MOVE INTO THE VCNTY OF THE AIRFIELD BY 19 UTC. THE CONVECTION
SHOULD LAST 3 TO 4 HOURS BEFORE MOVING EAST OF THE REGION BY 22-23
UTC. WINDS WILL BE OUT OF THE SW THIS AFTN AND WILL BE LIGHT
OVERNIGHT. AREAS OF MVFR FOG ARE LIKELY LATER TONIGHT. IN
FACT...DENSE FOG IS A GOOD BET IN PARTS OF THE WESTERN
PIEDMONT...BUT THIS WON/T BE INCLUDED AT KCLT AS THE AIRFIELD
TYPICALLY IS ONE OF THE LAST PLACES TO FOG UP.
ELSEWHERE...SCT SHRA WERE BEGINNING TO DEVELOP ACROSS THE REGION AT
ISSUANCE TIME. COVERAGE AND INTENSITY SHOULD INCREASE OVER THE NEXT
COUPLE HOURS AS AN UPPER LEVEL TROUGH CROSSES THE REGION.
HOWEVER...THE CONVECTION WILL BE SCT ENOUGH THAT ONLY VCTS WILL BE
CARRIED AT THE UPSTATE AND FOOTHILL TAF SITES. OF COURSE TEMPO OR
PREVAILING WILL BE ADDED TO ANY SITES THAT LOOK TO BE IMMEDIATELY
THREATENED. ONCE THE TROUGH PASSES...THERE SHOULD BE LESS MID AND
HIGH LEVEL CLOUDS OVERNIGHT. THIS WILL FAVOR THE DEVELOPMENT OF
DENSE VALLEY FOG IN THE NC MTNS...AS WELL AS SOME OF THE NON-MTN
RIVER VALLEYS. LIFR FOG HAS BEEN CARRIED AT KAND AND KHKY WITH
PREVAILING VLIFR AT KAVL.
OUTLOOK...BRIEF DRYING FROM THE WEST IS EXPECTED INTO FRIDAY. A COLD
FRONT WILL APPROACH THE REGION FROM THE NORTHWEST ON SATURDAY AND
MOVE EAST OF THE AREA ON SUNDAY. A LINE OF THUNDERSTORMS IS POSSIBLE
WITH THE FRONT ON SATURDAY. DRY AUTUMNAL HIGH PRES WILL DOMINATE THE
AREA EARLY NEXT WEEK.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...MCAVOY/SBK
SHORT TERM...JW
LONG TERM...DEO
AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
234 PM EDT THU SEP 6 2012
.SYNOPSIS...
SLIGHTLY DRIER AIR WILL PREVAIL ACROSS OUR REGION ON FRIDAY UNDER
WEAK HIGH PRESSURE. A STRONG COLD FRONT WILL MOVE ACROSS THE
AREA SATURDAY AND SATURDAY NIGHT WITH DRY AIR OVERSPREADING THE
REGION ON SUNDAY. DRY HIGH PRESSURE WILL SETTLE OVER THE REGION FOR
MUCH OF NEXT WEEK.
&&
.NEAR TERM /THROUGH FRIDAY/...
THE 16 UTC RAP AND WATER VAPOR IMAGERY CONTINUE TO INDICATE A WELL
DEFINED SHORT WAVE TROF SLOWLY PROGRESSING ACROSS THE NC MTNS. AHEAD
OF THE TROUGH...A STOUT AREA OF PVA EXITS OVER THE FOOTHILLS AND
WESTERN PIEDMONT. THE WAVE WILL CONTINUE TO SLOWLY TRANSLATE TO THE
ESE OVER THE NEXT SEVERAL HOURS. DEWPOINTS ARE QUITE HIGH OVER THE
WESTERN CAROLINAS AND NE GA...AND NOW THAT TEMPS HAVE WARMED INTO
THE L-M80S...SBCAPE VALUES HAVE RISEN TO 2000 J/KG OR HIGH IN MANY
AREAS. THIS HAS RESULTED IN THE DEVELOPMENT OF SHRA/TSTMS OVER THE
ERN UPSTATE AND SRN NC PIEDMONT. THE ACTIVITY SHOULD INCREASE IN
COVERAGE OVER THE NEXT COUPLE HOURS...THEN MOVE EAST OF THE REGION
BY EARLY EVENING. THE LATEST SPC MESOANALYSIS SHOWS A DCAPE MINIMUM
ACROSS THE REGION. FREEZING LEVELS ARE ALSO OVER 15KFT.
THEREFORE...NEITHER DAMAGING WINDS OR NOR HAIL WILL BE MUCH OF A
THREAT WITH STORMS THIS AFTN. THE STORMS SHOULD NOT BECOME VERY
ORGANIZED AND 30 TO 40 PERCENT COVERAGE...MAINLY OVER THE ERN
ZONES...STILL LOOKS REASONABLE. THE EXCEPTION TO THIS COULD BE THE
SRN NC PIEDMONT WHERE THE WAVE IS ALSO RESULTING IS INCREASED LLVL
CONVERGENCE.
LATE TONIGHT WIDESPREAD DENSE VALLEY FOG IS EXPECTED OVER THE NC
MTNS. WITH THE MID-LEVELS DRY OUT...FOR SHOULD ALSO BE A LITTLE MORE
WIDESPREAD ACROSS THE FOOTHILLS AND PIEDMONT...PARTICULARLY ALONG
THE LARGER RIVER VALLEYS.
SLIGHTLY DRIER AIR WILL WORK INTO THE REGION TOMORROW. A SHORT WAVE
RIDGE WILL ALSO SLOWLY TRANSLATE ACROSS THE FA. WITH MUCH DRIER AIR
ALOFT AND WARM H7 TEMPS CONVECTION WILL HAVE DIFFICULTLY DEVELOPING
TOMORROW AND I HAVE A DRY FORECAST FOR THE FOOTHILLS AND PIEDMONT.
ISOLATED STORMS ARE POSSIBLE OVER THE MTNS...PARTICULARLY OVER THE
HIGHER ELEVATIONS. WITH DRIER AIR AND LIGHT DOWNSLOPE
FLOW...TEMPERATURES WILL RISE INTO THE L90S ACROSS MUCH OF FOOTHILLS
AND PIEDMONT.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
COLD FROPA AND ASSOCIATED PRECIPITATION ARE THE BIG CONCERN FOR
FRIDAY NIGHT AND SATURDAY. 850MB WINDS WERE STRONGER ON 00Z NAM THAN
ON 06Z GFS...WHICH LED THE NAM TO PRODUCE STRONGER THETA-E ADVECTION
AND MOISTURE TRANSPORT AHEAD OF THE FRONT. 12Z NAM HAS WEAKER WINDS
MORE IN LINE WITH THE GFS AND ITS MOISTURE FIELDS REFLECT THE WEAKER
ADVECTION. DECENT AGREEMENT BETWEEN MODELS IN TIMING OF
FROPA...WHICH APPEARS TO OCCUR BETWEEN 12Z AND 18Z. PRECIPITABLE
WATER VALUES INCREASE AS THE FRONT ENTERS THE PIEDMONT...BUT THE
VALUES OVER THE MOUNTAINS ARE MORE EXTREME WITH RESPECT TO
CLIMATOLOGY. IF THE DYNAMICS ALONG THE FRONT WERE MORE IMPRESSIVE I
WOULD BE INCLINED TO GO WITH HIGHER QPF...BUT KEPT IT IN CHECK FOR
NOW.
WITH THE FRONT MOVING THROUGH EARLY IN THE DAY...INSTABILITY WILL BE
LIMITED...BUT FORECAST SOUNDINGS INDICATE ENOUGH CAPE TO WARRANT A
THUNDER MENTION. HOWEVER THE BETTER CHANCES FOR THUNDER WILL BE OVER
THE SC PIEDMONT ZONES DURING THE AFTERNOON AS THAT AREA WILL HAVE
MORE TIME TO DESTABILIZE.
COLD ADVECTION AND SUBSIDENCE SET IN QUICKLY BEHIND THE FRONT AND
MODELS AGREE PRECIP SHOULD END BY LATE SATURDAY EVENING. COULD SEE
SOME STRONG GAP WINDS IN THE MOUNTAIN VALLEYS OVERNIGHT SATURDAY
NIGHT GIVEN STRONG WINDS IN 1000-3000 FT LAYER AND WEAK INVERSION
PROFILE EXPECTED WITH PARTLY CLOUDY SKIES STILL IN PLACE.
SUNDAY LOOKS TO BE REFRESHINGLY COOLER AND LESS HUMID
WITH HIGHS IN THE MID 70S OVER THE MOUNTAINS TO THE LOWER 80S OVER
THE PIEDMONT. ONE ITEM OF NOTE IS THAT THE 00Z EC DEVELOPS THE
TROUGH INTO A CUTOFF UPPER LOW OVER THE NORTHEAST CONUS...WITH A
WEAK LOBE OF VORTICITY REACHING THE MOUNTAINS LATE SUNDAY. HOWEVER
THE MODEL DOES NOT PRODUCE ANY PRECIP AND THE WHOLE TROUGH IS LONG
GONE ON THE GFS AT THIS TIME ANYWAY...SO STILL FEEL PRETTY CONFIDENT
WITH DRY FORECAST SUNDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 200 PM EDT THURSDAY...BY 00Z MONDAY ALL MODELS ARE INDICATING
THAT DRY AIR WILL BE WELL ESTABLISHED AS THE AXIS OF THE UPPER
TROUGH WILL BE OVER OUR AREA AND MOVING EAST. COOLER CANADIAN HIGH
PRESSURE WILL BE MOVING FROM THE MISSISSIPPI VALLEY SUNDAY EVENING
TO BE POSITIONED OVER WEST VIRGINIA BY AROUND 00Z TUESDAY. HIGH
PRESSURE WILL SLOWLY SLIDE OFF THE EAST COAST IN MID WEEK AS THE
NEXT COLD FRONT APPROACHES FROM THE NORTHWEST. HPC HAS THE FRONT
OVER THE OHIO RIVER THURSDAY MORNING AS THAT POSITION MORE CLOSELY
FOLLOWS THE ECMWF WHICH HAS A MUCH MORE SHALLOW TROUGH CROSSING THE
GREAT LAKES AND HAS VERY LITTLE MOISTURE. THE GFS IS MUCH SLOWER
WITH A SHARPER UPPER TROUGH AND DEEPER MOISTURE. THEREFORE...ONLY
INCREASING THE CLOUDS A BIT OVER THE MOUNTAINS AT THE END OF THE
CURRENT FORECAST WHICH AT THIS POINT IS THURSDAY NIGHT.
TEMPERATURES WILL BE A FEW DEGREES BELOW NORMAL DURING THE FIRST
HALF OF THE WEEK AND WARMING TO JUST BELOW NORMAL BY THURSDAY.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
AT KCLT...SCT SHRA ARE BEGINNING TO DEVELOP OVER THE UPSTATE AND WRN
NC PIEDMONT ALONG A LINE FROM ABOUT 20 MILES NW OF THE AIRFIELD TO
40 MILES TO IT/S SOUTHWEST. WITH AN UNSTABLE ATMOSPHERE AND A WELL
DEFINED UPPER TROUGH APPROACHING...THE SHRA SHOULD GROW INTO TSTMS
AND MOVE INTO THE VCNTY OF THE AIRFIELD BY 19 UTC. THE CONVECTION
SHOULD LAST 3 TO 4 HOURS BEFORE MOVING EAST OF THE REGION BY 22-23
UTC. WINDS WILL BE OUT OF THE SW THIS AFTN AND WILL BE LIGHT
OVERNIGHT. AREAS OF MVFR FOG ARE LIKELY LATER TONIGHT. IN
FACT...DENSE FOG IS A GOOD BET IN PARTS OF THE WESTERN
PIEDMONT...BUT THIS WON/T BE INCLUDED AT KCLT AS THE AIRFIELD
TYPICALLY IS ONE OF THE LAST PLACES TO FOG UP.
ELSEWHERE...SCT SHRA WERE BEGINNING TO DEVELOP ACROSS THE REGION AT
ISSUANCE TIME. COVERAGE AND INTENSITY SHOULD INCREASE OVER THE NEXT
COUPLE HOURS AS AN UPPER LEVEL TROUGH CROSSES THE REGION.
HOWEVER...THE CONVECTION WILL BE SCT ENOUGH THAT ONLY VCTS WILL BE
CARRIED AT THE UPSTATE AND FOOTHILL TAF SITES. OF COURSE TEMPO OR
PREVAILING WILL BE ADDED TO ANY SITES THAT LOOK TO BE IMMEDIATELY
THREATENED. ONCE THE TROUGH PASSES...THERE SHOULD BE LESS MID AND
HIGH LEVEL CLOUDS OVERNIGHT. THIS WILL FAVOR THE DEVELOPMENT OF
DENSE VALLEY FOG IN THE NC MTNS...AS WELL AS SOME OF THE NON-MTN
RIVER VALLEYS. LIFR FOG HAS BEEN CARRIED AT KAND AND KHKY WITH
PREVAILING VLIFR AT KAVL.
OUTLOOK...BRIEF DRYING FROM THE WEST IS EXPECTED INTO FRIDAY. A COLD
FRONT WILL APPROACH THE REGION FROM THE NORTHWEST ON SATURDAY AND
MOVE EAST OF THE AREA ON SUNDAY. A LINE OF THUNDERSTORMS IS POSSIBLE
WITH THE FRONT ON SATURDAY. DRY AUTUMNAL HIGH PRES WILL DOMINATE THE
AREA EARLY NEXT WEEK.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...MCAVOY
SHORT TERM...JW
LONG TERM...DEO
AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
155 PM EDT THU SEP 6 2012
.SYNOPSIS...
SLIGHTLY DRIER AIR WILL PREVAIL ACROSS OUR REGION ON FRIDAY UNDER
WEAK HIGH PRESSURE. A STRONG COLD FRONT WILL MOVE ACROSS THE
AREA SATURDAY AND SATURDAY NIGHT WITH DRY AIR OVERSPREADING THE
REGION ON SUNDAY. DRY HIGH PRESSURE WILL SETTLE OVER THE REGION FOR
MUCH OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 105 PM EDT...POPS HAVE BEEN TRIMMED BACK A LITTLE OVER THE
NEXT COUPLE HOURS. HOWEVER...THE SHORT WAVE IS BECOMING MUCH BETTER
DEFINED ON THE WATER VAPOR IMAGERY AND ON THE LATEST RUNS OF THE
RAP. WITH LAPS CAPE VALUES NOW OVER 2000 J/KG ACROSS THE
FOOTHILLS...CONVECTION SHOULD BEGIN TO FIRE OVER THE FORECAST AREA
WITHIN THE HOUR.
AS OF 1030 AM EDT...THE LATEST RAP MATCHES WELL WITH THE WATER VAPOR
IMAGERY DEPICTION OF A SHORT WAVE ALONG THE NC/TN LINE. THIS FEATURE
WILL GRADUALLY MOVE EAST THROUGH THE DAY. THE NAM CURRENTLY HAS TOO
MUCH CONVECTION OVER THE WRN PART OF THE FA WITH THIS FEATURE AS
DOES THE RAP. THERE IS QUITE A BIT OF LOW CLOUD COVER ACROSS THE
FOOTHILLS AND PIEDMONT ATTM WHICH IS CUTTING OFF SFC HEATING. THIS
WILL RESULT IN CONTINUED SUPPRESSION OF CONVECTION INTO THE EARLY
AFTN. THEREAFTER...THE MODEL SOLUTIONS OF SCT CONVECTION DEVELOPING
OVER THE FOOTHILLS OR WESTERN PIEDMONT BY EARLY AFTN AND THEN
TRACKING EAST OF FA BY EARLY EVENING STILL LOOKS GOOD.
TO ACCOUNT FOR THESE TRENDS I/VE CUT BACK POPS THROUGH 17 UTC.
THEREAFTER I HAVE MUCH THE SAME WEATHER AND POP GRIDS THAT THE MID
SHIFT HAD.
AS OF 700 AM EDT...THE MID AND HIGH CLOUDS OVER THE REGION AHEAD OF
AN APPROACHING H5 SHORTWAVE HAVE THINNED A BIT...BUT THIS HAS
PERMITTED LOW STRATUS TO BECOME A BIT MORE WIDESPREAD...SO THERE IS
NO NET CHANGE IN THE SKY COVER. SHOWER COVERAGE IS SLOWLY RAMPING UP
OVER THE MTNS AS UPPER DPVA STARTS TO MOVE IN. THE MOST POTENT VORT
MAX IN THE UPSTREAM SHORTWAVE TROUGH SHOULD CROSS THE SRN
APPALACHIANS MAINLY THIS MORNING AND THEN MOVE OUT OVER THE PIEDMONT
THROUGH THE AFTN OR EARLY EVENING HOURS. WESTERLY DOWNSLOPING FLOW
AT LOW LEVELS MAY INITIALLY KEEP PRECIPITATION COVERAGE LOW EAST OF
THE MTNS THIS MORNING...BUT THE PASSING UPPER SUPPORT ALONG WITH
DEVELOPING LEE TROUGHING NEAR THE SURFACE SHOULD PROVIDE ENOUGH LIFT
FOR SCATTERED CONVECTION THIS AFTN. IN ADDITION TO THE
DOWNSLOPE...GRADUAL MID AND UPPER LEVEL DRYING IN THE SOUNDINGS
COULD LIMIT POPS SOMEWHAT. WILL THUS HEDGE TOWARD THE DRIER GFS
BASED MOS FOR POPS THIS AFTN. THE MID LEVEL DRYING...HOWEVER...COULD
INCREASE THE MICROBURST THREAT WITH ANY TSTMS THAT DO MANAGE TO
DEVELOP OVER THE PIEDMONT. IN ADDITION...MAX TEMPERATURES SHOULD BE
A COUPLE OF DEGREES WARMER THAN WED AFTN MOST AREAS. THIS WILL ADD
TO THE PIEDMONT INSTABILITY WHERE SFC DEWPOINTS SHOULD LINGER AROUND
70 DEGREES THROUGH LATE DAY.
STRONGER DRYING FROM THE TOP DOWN IS EXPECTED TONIGHT AS FLOW TURNS
NW TO N THROUGH A DEEP LAYER. THE BOUNDARY LAYER...HOWEVER...SHOULD
REMAIN FAIRLY MOIST TO CREATE THE POTENTIAL FOR FOG/VSBY PROBLEMS
OVERNIGHT. MIN TEMPS WILL LIKELY BE A CATEGORY COOLER THAN IN RECENT
DAYS.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
AS OF 245 AM THURSDAY...THE ATMOSPHERE IS PROGGED TO DRY OUT
CONSIDERABLY ON FRIDAY...WITH FORECAST SOUNDING PWATS DECREASING TO
AROUND ONE INCH BY AFTERNOON. MEANWHILE...A LOW AMPLITUDE UPPER
RIDGE AXIS WILL NOSE INTO THE REGION FROM THE SOUTHWEST. THESE
FACTORS WILL RESULT IN ONE OF THE LOWEST POP DAYS WE/VE SEEN IN SOME
TIME. NEVERTHELESS...STRONG INSOLATION (MAX TEMPS AROUND 90 EXPECTED
IN THE PIEDMONT) WILL ALLOW FOR MODERATE DESTABILIZATION...WHICH
SHOULD SUPPORT SOME HIGH TERRAIN CONVECTION BY LATE AFTERNOON.
FORECAST SOUNDINGS DEPICT A WEAK MID-LEVEL SUBSIDENCE INVERSION IN
THE PIEDMONT...SO IT IS UNCERTAIN AS TO HOW FAR INTO THE FOOTHILLS/
PIEDMONT THE ATMOSPHERE WILL BE ABLE TO SUSTAIN CONVECTION. SLIGHT
CHANCE POPS WERE INHERITED OUTSIDE THE MTNS...AND THIS STILL SEEMS
REASONABLE.
CONVECTION SHOULD DISSIPATE FATHER QUICKLY FRIDAY EVENING.
HOWEVER...STRONG HEIGHT FALLS WILL BE OCCURRING DURING THIS TIME
WEST THROUGH NORTHWEST OF THE AREA...DRIVING A STRONG COLD FRONT
TOWARD THE APPALACHIANS FRIDAY NIGHT. THERE ARE SLIGHT TIMING
DIFFERENCES IN THE OPERATIONAL MODELS...WITH THE NAM BEING ABOUT 3
HOURS FASTER THAN THE GFS. WE HAVE FAVORED THE SLIGHTLY FASTER
NAM...AS THERE WILL PROBABLY BE A MAJOR CONVECTIVE/COLD POOL
COMPONENT TO THE FRONTAL BAND...WHICH ALWAYS SEEMS TO RESULT IN
FASTER TIMING THAN DEPICTED BY THE MODELS. SPEAKING OF WHICH...
SATURDAY COULD BE AN INTERESTING CONVECTIVE DAY FOR OUR AREA...AS
THE COLD FRONT SEEMS DESTINED TO SWEEP ACROSS THE PIEDMONT DURING
PEAK HEATING TIME. THERE MAY BE EXTENSIVE MORNING HIGH CLOUDS AND
MID-LEVEL LAPSE RATES WILL BE WEAK...WHICH WOULD LIKELY LIMIT CAPE
VALUES TO WELL UNDER 2000 J/KG. NEVERTHELESS...IT APPEARS SHEAR WILL
BE FAIRLY STRONG...PARTICULARLY IN THE LOWER LEVELS...SO THERE IS A
LOW-END ORGANIZED SEVERE WEATHER THREAT.
CHANCE POPS WILL BEGIN OVER THE SOUTHWEST NC MTNS LATE FRIDAY
NIGHT...INCREASING TO LIKELY ACROSS THE MTNS BY EARLY AFTERNOON...
WITH HIGH CHANCES EXTENDING TO THE EAST DURING MID/LATE AFTERNOON.
THE MODEL CONSENSUS IS TO SWEEP ALL CONVECTION EAST OF THE AREA BY
00Z SUNDAY...SO POPS HAVE BEEN ADJUSTED DOWN SAT NIGHT THROUGH EARLY
SUNDAY. (SLIGHT/LOW CHANCES AT 00Z...DIMINISHING TO LESS THAN 20
PERCENT BY 12Z). COOL ADVECTION FLOW WILL RESULT IN MIN TEMPS ABOUT
A CAT BELOW NORMAL SUNDAY MORNING.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 130 AM EDT THURSDAY...L/WV TROUGH AXIS WITH DRY AND COOLER
NORTHERLY LLVL FLOW IS PROGGED TO BE ATOP THE REGION ON MONDAY.
TEMPERATURES WILL START OFF THE PERIOD 2-3 CATEGORIES BELOW CLIMO.
SFC RIDGE AXIS WILL BUILD IN ON TUESDAY AS UPPER TROUGH AXIS
PROGRESSES OFFSHORE AND GIVES WAY TO NW FLOW ALOFT. CONTINUED DRY
CONDITIONS ARE EXPECTED WITH TEMPERATURES NEAR PERSISTENCE. DEEP
LAYERED RIDGING WILL THEN DEVELOP ACRS THE SE CONUS BY THE END OF THE
PERIOD AND MAX TEMPERATURES ON WEDNESDAY WILL MODERATE A FEW DEG F
BUT STILL AVERAGE BELOW NORMAL.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AT KCLT...SCT SHRA ARE BEGINNING TO DEVELOP OVER THE UPSTATE AND WRN
NC PIEDMONT ALONG A LINE FROM ABOUT 20 MILES NW OF THE AIRFIELD TO
40 MILES TO IT/S SOUTHWEST. WITH AN UNSTABLE ATMOSPHERE AND A WELL
DEFINED UPPER TROUGH APPROACHING...THE SHRA SHOULD GROW INTO TSTMS
AND MOVE INTO THE VCNTY OF THE AIRFIELD BY 19 UTC. THE CONVECTION
SHOULD LAST 3 TO 4 HOURS BEFORE MOVING EAST OF THE REGION BY 22-23
UTC. WINDS WILL BE OUT OF THE SW THIS AFTN AND WILL BE LIGHT
OVERNIGHT. AREAS OF MVFR FOG ARE LIKELY LATER TONIGHT. IN
FACT...DENSE FOG IS A GOOD BET IN PARTS OF THE WESTERN
PIEDMONT...BUT THIS WON/T BE INCLUDED AT KCLT AS THE AIRFIELD
TYPICALLY IS ONE OF THE LAST PLACES TO FOG UP.
ELSEWHERE...SCT SHRA WERE BEGINNING TO DEVELOP ACROSS THE REGION AT
ISSUANCE TIME. COVERAGE AND INTENSITY SHOULD INCREASE OVER THE NEXT
COUPLE HOURS AS AN UPPER LEVEL TROUGH CROSSES THE REGION.
HOWEVER...THE CONVECTION WILL BE SCT ENOUGH THAT ONLY VCTS WILL BE
CARRIED AT THE UPSTATE AND FOOTHILL TAF SITES. OF COURSE TEMPO OR
PREVAILING WILL BE ADDED TO ANY SITES THAT LOOK TO BE IMMEDIATELY
THREATENED. ONCE THE TROUGH PASSES...THERE SHOULD BE LESS MID AND
HIGH LEVEL CLOUDS OVERNIGHT. THIS WILL FAVOR THE DEVELOPMENT OF
DENSE VALLEY FOG IN THE NC MTNS...AS WELL AS SOME OF THE NON-MTN
RIVER VALLEYS. LIFR FOG HAS BEEN CARRIED AT KAND AND KHKY WITH
PREVAILING VLIFR AT KAVL.
OUTLOOK...BRIEF DRYING FROM THE WEST IS EXPECTED INTO FRIDAY. A COLD
FRONT WILL APPROACH THE REGION FROM THE NORTHWEST ON SATURDAY AND
MOVE EAST OF THE AREA ON SUNDAY. A LINE OF THUNDERSTORMS IS POSSIBLE
WITH THE FRONT ON SATURDAY. DRY AUTUMNAL HIGH PRES WILL DOMINATE THE
AREA EARLY NEXT WEEK.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...MCAVOY
SHORT TERM...JDL
LONG TERM...CSH
AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
109 PM EDT THU SEP 6 2012
.SYNOPSIS...
A WEAK FRONTAL BOUNDARY WILL DRIFT ACROSS THE REGION TODAY FOLLOWED
BY SLIGHTLY DRIER AIR FOR FRIDAY. A STRONG COLD FRONT WILL MOVE
ACROSS THE AREA SATURDAY AND SATURDAY NIGHT WITH DRY AIR
OVERSPREADING THE REGION ON SUNDAY. DRY HIGH PRESSURE WILL SETTLE
OVER THE REGION EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 105 PM EDT...POPS HAVE BEEN TRIMMED BACK A LITTLE OVER THE
NEXT COUPLE HOURS. HOWEVER...THE SHORT WAVE IS BECOMING MUCH BETTER
DEFINED ON THE WATER VAPOR IMAGERY AND ON THE LATEST RUNS OF THE
RAP. WITH LAPS CAPE VALUES NOW OVER 2000 J/KG ACROSS THE
FOOTHILLS...CONVECTION SHOULD BEGIN TO FIRE OVER THE FORECAST AREA
WITHIN THE HOUR.
AS OF 1030 AM EDT...THE LATEST RAP MATCHES WELL WITH THE WATER VAPOR
IMAGERY DEPICTION OF A SHORT WAVE ALONG THE NC/TN LINE. THIS FEATURE
WILL GRADUALLY MOVE EAST THROUGH THE DAY. THE NAM CURRENTLY HAS TOO
MUCH CONVECTION OVER THE WRN PART OF THE FA WITH THIS FEATURE AS
DOES THE RAP. THERE IS QUITE A BIT OF LOW CLOUD COVER ACROSS THE
FOOTHILLS AND PIEDMONT ATTM WHICH IS CUTTING OFF SFC HEATING. THIS
WILL RESULT IN CONTINUED SUPPRESSION OF CONVECTION INTO THE EARLY
AFTN. THEREAFTER...THE MODEL SOLUTIONS OF SCT CONVECTION DEVELOPING
OVER THE FOOTHILLS OR WESTERN PIEDMONT BY EARLY AFTN AND THEN
TRACKING EAST OF FA BY EARLY EVENING STILL LOOKS GOOD.
TO ACCOUNT FOR THESE TRENDS I/VE CUT BACK POPS THROUGH 17 UTC.
THEREAFTER I HAVE MUCH THE SAME WEATHER AND POP GRIDS THAT THE MID
SHIFT HAD.
AS OF 700 AM EDT...THE MID AND HIGH CLOUDS OVER THE REGION AHEAD OF
AN APPROACHING H5 SHORTWAVE HAVE THINNED A BIT...BUT THIS HAS
PERMITTED LOW STRATUS TO BECOME A BIT MORE WIDESPREAD...SO THERE IS
NO NET CHANGE IN THE SKY COVER. SHOWER COVERAGE IS SLOWLY RAMPING UP
OVER THE MTNS AS UPPER DPVA STARTS TO MOVE IN. THE MOST POTENT VORT
MAX IN THE UPSTREAM SHORTWAVE TROUGH SHOULD CROSS THE SRN
APPALACHIANS MAINLY THIS MORNING AND THEN MOVE OUT OVER THE PIEDMONT
THROUGH THE AFTN OR EARLY EVENING HOURS. WESTERLY DOWNSLOPING FLOW
AT LOW LEVELS MAY INITIALLY KEEP PRECIPITATION COVERAGE LOW EAST OF
THE MTNS THIS MORNING...BUT THE PASSING UPPER SUPPORT ALONG WITH
DEVELOPING LEE TROUGHING NEAR THE SURFACE SHOULD PROVIDE ENOUGH LIFT
FOR SCATTERED CONVECTION THIS AFTN. IN ADDITION TO THE
DOWNSLOPE...GRADUAL MID AND UPPER LEVEL DRYING IN THE SOUNDINGS
COULD LIMIT POPS SOMEWHAT. WILL THUS HEDGE TOWARD THE DRIER GFS
BASED MOS FOR POPS THIS AFTN. THE MID LEVEL DRYING...HOWEVER...COULD
INCREASE THE MICROBURST THREAT WITH ANY TSTMS THAT DO MANAGE TO
DEVELOP OVER THE PIEDMONT. IN ADDITION...MAX TEMPERATURES SHOULD BE
A COUPLE OF DEGREES WARMER THAN WED AFTN MOST AREAS. THIS WILL ADD
TO THE PIEDMONT INSTABILITY WHERE SFC DEWPOINTS SHOULD LINGER AROUND
70 DEGREES THROUGH LATE DAY.
STRONGER DRYING FROM THE TOP DOWN IS EXPECTED TONIGHT AS FLOW TURNS
NW TO N THROUGH A DEEP LAYER. THE BOUNDARY LAYER...HOWEVER...SHOULD
REMAIN FAIRLY MOIST TO CREATE THE POTENTIAL FOR FOG/VSBY PROBLEMS
OVERNIGHT. MIN TEMPS WILL LIKELY BE A CATEGORY COOLER THAN IN RECENT
DAYS.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
AS OF 245 AM THURSDAY...THE ATMOSPHERE IS PROGGED TO DRY OUT
CONSIDERABLY ON FRIDAY...WITH FORECAST SOUNDING PWATS DECREASING TO
AROUND ONE INCH BY AFTERNOON. MEANWHILE...A LOW AMPLITUDE UPPER
RIDGE AXIS WILL NOSE INTO THE REGION FROM THE SOUTHWEST. THESE
FACTORS WILL RESULT IN ONE OF THE LOWEST POP DAYS WE/VE SEEN IN SOME
TIME. NEVERTHELESS...STRONG INSOLATION (MAX TEMPS AROUND 90 EXPECTED
IN THE PIEDMONT) WILL ALLOW FOR MODERATE DESTABILIZATION...WHICH
SHOULD SUPPORT SOME HIGH TERRAIN CONVECTION BY LATE AFTERNOON.
FORECAST SOUNDINGS DEPICT A WEAK MID-LEVEL SUBSIDENCE INVERSION IN
THE PIEDMONT...SO IT IS UNCERTAIN AS TO HOW FAR INTO THE FOOTHILLS/
PIEDMONT THE ATMOSPHERE WILL BE ABLE TO SUSTAIN CONVECTION. SLIGHT
CHANCE POPS WERE INHERITED OUTSIDE THE MTNS...AND THIS STILL SEEMS
REASONABLE.
CONVECTION SHOULD DISSIPATE FATHER QUICKLY FRIDAY EVENING.
HOWEVER...STRONG HEIGHT FALLS WILL BE OCCURRING DURING THIS TIME
WEST THROUGH NORTHWEST OF THE AREA...DRIVING A STRONG COLD FRONT
TOWARD THE APPALACHIANS FRIDAY NIGHT. THERE ARE SLIGHT TIMING
DIFFERENCES IN THE OPERATIONAL MODELS...WITH THE NAM BEING ABOUT 3
HOURS FASTER THAN THE GFS. WE HAVE FAVORED THE SLIGHTLY FASTER
NAM...AS THERE WILL PROBABLY BE A MAJOR CONVECTIVE/COLD POOL
COMPONENT TO THE FRONTAL BAND...WHICH ALWAYS SEEMS TO RESULT IN
FASTER TIMING THAN DEPICTED BY THE MODELS. SPEAKING OF WHICH...
SATURDAY COULD BE AN INTERESTING CONVECTIVE DAY FOR OUR AREA...AS
THE COLD FRONT SEEMS DESTINED TO SWEEP ACROSS THE PIEDMONT DURING
PEAK HEATING TIME. THERE MAY BE EXTENSIVE MORNING HIGH CLOUDS AND
MID-LEVEL LAPSE RATES WILL BE WEAK...WHICH WOULD LIKELY LIMIT CAPE
VALUES TO WELL UNDER 2000 J/KG. NEVERTHELESS...IT APPEARS SHEAR WILL
BE FAIRLY STRONG...PARTICULARLY IN THE LOWER LEVELS...SO THERE IS A
LOW-END ORGANIZED SEVERE WEATHER THREAT.
CHANCE POPS WILL BEGIN OVER THE SOUTHWEST NC MTNS LATE FRIDAY
NIGHT...INCREASING TO LIKELY ACROSS THE MTNS BY EARLY AFTERNOON...
WITH HIGH CHANCES EXTENDING TO THE EAST DURING MID/LATE AFTERNOON.
THE MODEL CONSENSUS IS TO SWEEP ALL CONVECTION EAST OF THE AREA BY
00Z SUNDAY...SO POPS HAVE BEEN ADJUSTED DOWN SAT NIGHT THROUGH EARLY
SUNDAY. (SLIGHT/LOW CHANCES AT 00Z...DIMINISHING TO LESS THAN 20
PERCENT BY 12Z). COOL ADVECTION FLOW WILL RESULT IN MIN TEMPS ABOUT
A CAT BELOW NORMAL SUNDAY MORNING.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
AS OF 130 AM EDT THURSDAY...L/WV TROUGH AXIS WITH DRY AND COOLER
NORTHERLY LLVL FLOW IS PROGGED TO BE ATOP THE REGION ON MONDAY.
TEMPERATURES WILL START OFF THE PERIOD 2-3 CATEGORIES BELOW CLIMO.
SFC RIDGE AXIS WILL BUILD IN ON TUESDAY AS UPPER TROUGH AXIS
PROGRESSES OFFSHORE AND GIVES WAY TO NW FLOW ALOFT. CONTINUED DRY
CONDITIONS ARE EXPECTED WITH TEMPERATURES NEAR PERSISTENCE. DEEP
LAYERED RIDGING WILL THEN DEVELOP ACRS THE SE CONUS BY THE END OF THE
PERIOD AND MAX TEMPERATURES ON WEDNESDAY WILL MODERATE A FEW DEG F
BUT STILL AVERAGE BELOW NORMAL.
&&
.AVIATION /17Z THURSDAY THROUGH MONDAY/...
AT KCLT...THE LOW CLOUD IR SATELLITE PRODUCT SHOWS IFR CIGS KNOCKING
ON THE DOOR AT CLT. WILL NEED TO CARRY TEMPO IFR FOR AT LEAST AN
HOUR. THERE IS NOT TOO MUCH MID OR HIGH CLOUD AT PRESENT ABOVE THE
PIEDMONT STRATUS LAYER...SO IT SHOULD BURN OFF FAIRLY QUICKLY.
ATTENTION WILL THEN TURN TO THE PASSING WEAK SHORTWAVE...WITH BETTER
FORCING FOR SHRA OR TSRA AFTER 18Z. WINDS WILL STAY SW TODAY WITH
LEE TROUGHING...BUT LIKELY TURN WNW THIS EVENING. SOME DRYING IS
INDICATED TONIGHT...BUT LINGERING BL MOISTURE COULD CREATE FOG/LOW
CLOUD PROBLEMS TOWARD DAYBREAK FRI.
ELSEWHERE...AN IFR STRATUS LAYER HAS DEVELOPED THIS MORNING AS MID
AND HIGH CLOUDS THINNED OUT OVERNIGHT. THIS SHOULD BURN OFF FAIRLY
QUICKLY...WITH MAINLY VFR CUMULUS FILLING IN WITH HEATING OF THE
MOIST BOUNDARY LAYER. WILL START OFF WITH VCSH AT KAVL AND KHKY
FIRST...AND THEN INTRODUCE VCTS FOR MAINLY THE AFTERNOON
HOURS...WITH THE MOVING WINDOW FROM WEST TO EAST. ANY FURTHER
RESTRICTIONS WOULD BE DUE TO CONVECTIVE SHOWERS AND THESE SHOULD BE
SCATTERED AT BEST. SW WINDS AHEAD OF THE LEE TROUGH TODAY WILL TURN
NW OVERNIGHT...EXCEPT FOR WINDS REMAINING NW AT KAVL THROUGH THE
PERIOD. PROFILES WILL DRY OUT FROM THE TOP DOWN TONIGHT...BUT
LINGERING BL MOISTURE COULD CREATE FOG/VSBY PROBLEMS OVERNIGHT. WILL
ONLY FEATURE IFR FOG AT KAVL...WITH MVFR FOG AT KHKY AND KAND...AS A
STARTING POINT.
OUTLOOK...BRIEF DRYING FROM THE WEST IS EXPECTED INTO FRIDAY. A COLD
FRONT WILL APPROACH THE REGION FROM THE NORTHWEST ON SATURDAY AND
MOVE EAST OF THE AREA ON SUNDAY. DRY HIGH PRES WILL DOMINATE THE
AREA EARLY NEXT WEEK.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...CSH
NEAR TERM...MCAVOY
SHORT TERM...JDL
LONG TERM...CSH
AVIATION...HG