Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/25/12
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
145 PM PDT SUN SEP 23 2012
.SYNOPSIS...
HIGH PRESSURE AND HOT CONDITIONS WILL GIVE WAY TO A TROUGH OF LOW
PRESSURE ON MONDAY. THIS WILL BRING A CHANGE TO THE WEATHER...WITH
DEEPER AND MORE PERSISTENT LOW CLOUDS...AS WELL AS GUSTY WEST WINDS
IN THE MOUNTAINS AND DESERTS AT TIMES. A WARMING TREND SHOULD BEGIN
BY MIDWEEK AND CONTINUE THROUGH FRIDAY.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.SHORT TERM (TODAY THROUGH TUESDAY)...
THE HRRR MODEL WAS SLOW TO CLEAR THE LOW CLOUDS OUT OF THE COASTAL
WATERS TODAY...AND HAD THE RIGHT IDEA UP TO NOW. THERE IS STILL SOME
LOW CLOUDS SOUTH COAST THAT SHOULD DISSIPATE LATE AFTERNOON. IT
BRINGS A SLIVER OF LOW CLOUDS INTO THE EXTREME SOUTH COAST..QUITE
LOW IN FACT...AND SUPPORTS AT LEAST PATCHY DENSE FOG. HAVE PLACED
PATCHY DENSE FOG IN THE FORECAST FOR THE HIGHER COASTAL AREAS AND
LOWER VALLEY AREAS FOR TONIGHT.
FOR MONDAY AND TUESDAY...INLAND TROUGHING IS EXPECTED...AND
SHOULD INTRODUCE MORE LOW CLOUDS...AND COOLING... ESPECIALLY INLAND
COASTAL AREAS AND WESTERN VALLEYS. GUSTY WESTERLY WINDS WILL DESCEND
ON THE MOUNTAIN AND DESERT AREAS...WITH A PEAK ON MONDAY AFTERNOON
OR EARLY EVENING. SPEEDS SHOULD BE BELOW ADVISORY STRENGTH.
&&
.LONG TERM (WEDNESDAY THROUGH SATURDAY)...
THE MIDWEEK TROUGH IS EXPECTED TO PUSH EAST AND THE FLOW SHOULD
TREND OFFSHORE ON THURSDAY AND FRIDAY FOR LESS MARINE LAYER LOW
CLOUDS AND A WARMING TREND. THE GFS ENSEMBLE MEAN AND ECMWF PLACE
THE LOW SOMEWHERE FROM 100 TO 500 MILES TO OUR SOUTHWEST WHICH POINT
TOWARD EITHER HOT...OR EVEN HOTTER. I HAVE ADJUSTED THE TEMPERATURE
GRIDS UP TO REFLECT THE POTENTIAL FOR A GOOD WARMUP INTO NEXT
WEEKEND. A TROPICAL FEATURE COULD GET CLOSE ENOUGH TO GIVE US SOME
HIGH CLOUDS AND REINFORCE THE OFFSHORE FLOW...BUT WILL USE A TONED
DOWN APPROACH COMPARED TO THE GFS FOR NOW.
&&
.AVIATION...
232030Z...COASTAL AREAS...PATCHY LOW CLOUDS AND FOG LINGERING AT THE
BEACHES THIS AFTERNOON. CLOUD BASES ARE AROUND 300 FT MSL AND TOPS
AROUND 800 FT MSL. PATCHY VIS 3-5SM. THE LOW CLOUDS AND FOG WILL
LIKELY RETURN TO THE COASTAL AREA TAF SITES AFT 08Z MON. EXPECT
BKN-OVC CIGS WITH BASES AROUND 300 FT MSL AND TOPS NEAR 1000 FT
MSL...ALONG WITH PATCHY VIS 3-5SM...LOCALLY BLO 1SM. KSAN AND KCRQ
ARE THE MOST LIKELY TO BE AFFECTED WHILE KSNA IS NOT LIKELY TO BE
AFFECTED. EXPECT CLEARING TO THE BEACHES BY 17Z MON. ABV THE MARINE
LAYER...SCT CLOUDS LAYERED FROM 7000 FT TO 15000 FT THROUGH MON.
ELSEWHERE...SCT LAYERS 7000 FT TO 15000 FT.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...SMALL
AVIATION/MARINE...PG
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
915 AM PDT SUN SEP 23 2012
.SYNOPSIS...
HIGH PRESSURE ALOFT OVER THE WEST WILL BRING ABOVE AVERAGE
TEMPERATURES TO THE REGION TODAY. BY MONDAY A TROUGH OF LOW PRESSURE
WILL BEGIN TO DEEPEN OVER THE WESTERN STATES...AND AFFECT THE AREA
THROUGH WEDNESDAY. IT WILL BRING MORE PERSISTENT LOW CLOUDS...AS
WELL AS GUSTY WEST WINDS TO THE MOUNTAINS AND DESERTS AT TIMES. A
WARMING TREND SHOULD BEGIN BY MIDWEEK AND CONTINUE THROUGH FRIDAY.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.SHORT TERM (TODAY THROUGH TUESDAY)...
THE HRRR MODEL IS SLOW TO CLEAR THE LOW CLOUDS OUT OF THE COASTAL
WATERS...AND IT LOOKS LIKE IF IT BRINGS IT BACK...IT WOULD BE AFTER
04Z THIS EVENING. WITH SUCH A LOW...STRONG INVERSION...WARM TO HOT
TODAY LOOKS GOOD.
FOR MONDAY AND TUESDAY...TROUGHING WILL INTRODUCE COOLING...MORE LOW
CLOUDS...AND COOLING...ESPECIALLY INLAND COASTAL AREAS AND WESTERN
VALLEYS. THE FIRST DECENT WESTERLY WINDS IN A WHILE SHOULD SHOW UP
IN THE MOUNTAINS AND DESERTS...PEAKING MONDAY SOMETIME LATE
AFTERNOON OR EARLY EVENING.
&&
.LONG TERM (WEDNESDAY THROUGH SATURDAY)...
ONSHORE FLOW WILL WEAKEN AND WEAK HIGH PRESSURE MAY RETURN FOR NEXT
WEEKEND FOR A WARMING TREND AND SHALLOWER MARINE LAYER.
PRECIPITATION FROM THE REMNANTS OF TROPICAL CYCLONE MIRIAM WILL MOST
LIKELY REMAIN TO THE SOUTH AND EAST OF SOUTHERN CALIFORNIA THOUGH
SOME HIGH CLOUDS ARE POSSIBLE AT TIMES NEXT WEEKEND.
&&
.AVIATION...
231530Z...COASTAL AREAS...LOW CLOUDS AND FOG HAVE BEGUN TO LIFT THIS
MORNING...BUT PATCHES REMAIN ALONG THE SOUTHERN SAN DIEGO COUNTY
COAST WHERE CIGS ARE LOCALLY BKN-OVC WITH BASES AROUND 200 FT MSL
AND TOPS TO 800 FT MSL. FOG WITH LOCAL VIS BLO 3SM ACCOMPANIES THE
LOW CLOUDS. EXPECT ONLY SCT LOW CLOUDS WITH UNRESTRICTED VIS BY 17Z.
THE LOW CLOUDS AND FOG WILL LIKELY TO RETURN TO THE COASTAL AREAS
AFT 08Z MON WITH CIGS AND VIS SIMILAR TO THIS MORNING. ABV THE
MARINE LAYER...SCT-BKN CLOUDS ABV 15000 FT THROUGH MON.
ELSEWHERE...SCT-BKN LAYERS ABV 15000 FT.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...SMALL
AVIATION/MARINE...PG
AREA FORECAST DISCUSSION
NWS MIAMI FL
153 AM EDT SUN SEP 23 2012
.AVIATION...
WET PATTERN TO CONTINUE ACROSS SOUTH FLORIDA THROUGH THE NEXT 24
HOURS. COLD FRONT WILL PUSH FURTHER SOUTH ACROSS THE FLORIDA
PENINSULA THROUGH THE DAY. THIS COMBINED WITH PASSING UPPER LEVEL
DISTURBANCES WILL ENHANCE SHRA/TSRA DEVELOPMENT AGAIN TODAY. KEPT
VCSH THROUGH THE MORNING HOURS TRANSITIONING TO VCTS THROUGH THE
AFTERNOON. BRIEF PERIODS OF MVFR/IFR CAN BE EXPECTED WITHIN ANY
TSRAS AND HEAVY SHRAS.
&&
.PREV DISCUSSION... /ISSUED 928 PM EDT SAT SEP 22 2012/
UPDATE...
ALL THE URBAN FLOOD ADVISORIES ISSUED EARLIER IN THE EVENING HAVE
BEEN DROPPED.. LATEST RADAR RETURNS INDICATE JUST LIGHT TO
MODERATE SHOWERS ACROSS THE CWA.
THE SHORT TERM FORECAST WAS UPDATED TO REFLECT THE LACK OF
CONVECTION CURRENTLY ACROSS THE REGION. HOWEVER...LATEST GUIDANCE
AND WATER VAPOR IMAGERY INDICATED AN UPPER LEVEL SHORT WAVE TROUGH
ENTERING THE EASTERN GULF THAT COULD TRIGGER ANOTHER ROUND OF
CONVECTION DURING THE EARLY MORNING HOURS ON SUNDAY. THE OOZ SOUNDING
INDICATED CONSIDERABLE MOISTURE LINGERING ACROSS THE AREA WITH THE
PWAT NEAR 2.4 INCHES WITH WESTERLY FLOW THROUGH MOST OF THE
ATMOSPHERE. THE RECENT GUIDANCE ALSO INDICATED THE POTENTIAL FOR
ADDITIONAL CONVECTION OVER NIGHT. SO FOR THE REMAINING EVENING
HOURS JUST ISOLATED TO SCATTERED SHOWERS AND AN OCCASIONAL
THUNDERSTORM IS FORECAST WITH GREATER COVERAGE AND AN INCREASE IN
POTENTIAL FOR SHOWERS AND THUNDERSTORMS EXPECTED DURING THE EARLY
MORNING HOURS ON SUNDAY.
60
PREV DISCUSSION... /ISSUED 234 PM EDT SAT SEP 22 2012/
SHORT TERM (TONIGHT-MONDAY NIGHT)... AFTER A BUSY START TO THE
DAY THIS MORNING DUE TO FLOODING ALONG THE EAST COAST FROM MIAMI-
DADE TO PALM BEACH...THE LATEST HRRR MODEL REFLECTIVITIES HAVE
INITIALIZED WELL WITH THE CURRENT PATTERN AND CONTINUE TO INDICATE
ANOTHER ROUND OF ACTIVITY REDEVELOPING THROUGH THE MID TO LATE
AFTERNOON AND EVENING PERIODS. FOR COVERAGE...IT IS INDICATING THE
BULK OF THE HEAVIEST ACTIVITY SETTING UP OVER THE SOUTHERN HALF OF
THE LOCAL AREA WITH ANOTHER 1-2 INCHES OF RAINFALL POSSIBLE IN THE
HEAVIEST ACTIVITY. THIS SEEMS REASONABLE AS THE LATEST VISIBLE
SATELLITE IMAGERY SHOWS THE LARGEST BREAKS IN CLOUD COVERAGE OVER
THESE SOUTHERN AREAS WHERE TEMPERATURES HAVE QUICKLY INCREASED
OVER THE PAST 1-2 HRS. AS A RESULT...FLOODING REMAINS THE MAIN
CONCERN INTO THE EVENING HOURS. IF THIS ACTIVITY SETS UP OVER THE
SAME AREAS AS THIS MORNING WHERE 2-4 INCHES WERE RECORDED...MAINLY
FROM AROUND JUST SE OF CUTLER BAY TO NORTH MIAMI BEACH...FLASH
FLOODING CANNOT BE RULED OUT.
TONIGHT THROUGH SUNDAY NIGHT...THE COLD FRONT ENTERING THE REGION
FROM THE NORTH IS PROGGED TO CONTINUE SOUTH INTO NORTHERN AND
CENTRAL FLORIDA THROUGH THE FIRST HALF OF THE DAY SUNDAY FOLLOWED BY
A SURGE OF MUCH DRIER AIR BEFORE STALLING. UNFORTUNATELY...THE DEEP
LAY MOISTURE AXIS WITH AROUND 2" PWAT VALUES EXTENDING FROM NE TO SW
ACROSS THE AREA WILL REMAIN IN PLACE THROUGH SUNDAY WITH ONLY SOME
DRYING POSSIBLE ACROSS THE NORTHERN HALF OR THE LAKE REGION BY
TOMORROW NIGHT. THIS COMBINED WITH WEAK UPPER PULSES OF ENERGY
TRANSLATING NORTHEAST AHEAD OF THE BROAD UPPER TROUGH JUST WEST OF
THE AREA WILL KEEP THE RAIN AND FLOOD CHANCES AS THE PRIMARY
CONCERNS THROUGH SUNDAY. ADDITIONAL RAINFALL ACCUMULATIONS COULD
REACH THE 1 TO 3 INCH RANGE WITH LOCALIZED HIGHER AMOUNTS
POSSIBLE.
MONDAY AND MONDAY NIGHT...THE LATEST NUMERICAL GUIDANCE REMAINS IN
DECENT AGREEMENT AND INDICATES THE BROAD UPPER TROUGH OVER THE
EASTERN STATES SHIFTING EAST AND THE MUCH DRIER AIR THAT WAS
PREVIOUSLY DISCUSSED SHIFTING FARTHER SOUTH INTO OUR AREA IN THE
WAKE OF THE FRONTAL BOUNDARY. AS A RESULT...DRY AIR WITH LOWER
RAINFALL CHANCES CAN BE ANTICIPATED.
LONG TERM...(TUESDAY-FRIDAY)
THE UPPER RIDGE OVER THE ROCKIES BEGINS TO BREAK DOWN AS AN UPPER
LOW MOVES FROM THE PACIFIC NORTHWEST TOWARD THE CENTRAL ROCKIES.
THIS SHOVES THE E U.S. TROUGH NE WITH THE COLD FRONT STALLED N OF
LAKE OKEECHOBEE. THIS DRIES THE ATMOSPHERE SOMEWHAT FROM THE N TO
S ACROSS FLA BUT LONG RANGE MODELS STILL APPEAR TO DEVELOP AN
UPPER LOW OVER THE GULF AND WITH THE SW FLOW MAY KEEP AMPLE
ATMOSPHERIC MOISTURE OVER THE AREA. PLUS...ANOTHER TROPICAL WAVE
MAY NEAR THE AREA MIDWEEK NEXT WEEK. AT HIS TIME...WILL STAY WITH
GUIDANCE.
MARINE...
RAIN CHANCES WILL REMAIN UP ACROSS THE MARINE AREAS THROUGH SUNDAY
BEFORE DRIER AIR ASSOCIATED WITH A COLD FRONT SPREADS SOUTH ACROSS
THE AREA MONDAY. MODERATE NORTHEAST WINDS WILL FOLLOW THIS BOUNDARY
AND LEAD TO INCREASING SEAS MONDAY THROUGH TUESDAY OVER THE ATLANTIC
WATERS.
FIRE WEATHER...
ALTHOUGH SOME DRIER AIR IS FORECAST TO SPREAD SOUTH INTO THE AREA
THROUGH THE FIRST HALF OF THE UPCOMING WEEK...RELATIVE HUMIDITIES
ARE FORECAST TO REMAIN ABOVE CRITICAL LEVELS EACH DAY. AS A
RESULT...THERE ARE NO RED FLAG CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 81 77 86 77 / 60 50 20 20
FORT LAUDERDALE 86 75 86 77 / 70 50 30 30
MIAMI 88 75 88 77 / 70 60 30 30
NAPLES 87 74 89 74 / 40 40 20 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...15/JR
AVIATION/RADAR...10/CD
AREA FORECAST DISCUSSION
NWS LINCOLN IL
300 PM CDT SUN SEP 23 2012
.DISCUSSION...
ISSUED 300 PM CDT SUN SEP 23 2012
12Z MODELS ARE FAIRLY SIMILAR EARLY THIS WEEK AND THEN DIVERGE
DURING 2ND HALF OF THE WEEK. USED A MODEL BLEND AND THINK GFS MAY
BE TOO FAR NORTH AND TOO WET WITH QPF THU NIGHT WHILE ECMWF MODEL
APPEARS TOO FAR SOUTH.
SHORT TERM...TODAY THROUGH TUESDAY NIGHT
WILL ISSUE FROST ADVISORY OVERNIGHT AND EARLY MONDAY MORNING FOR
ENTIRE CWA OF CENTRAL AND SOUTHEAST IL WITH LOWS GENERALLY IN THE
MID 30S. THESE LOWS ARE GENERALLY NEAR OR BELOW COOLER MET
GUIDANCE LOWS WHICH WORKED BETTER FOR LOWS EARLY THIS MORNING.
FROST WILL NOT BE QUITE AS WIDESPREAD IN AREAS SW OF SPRINGFIELD
WHERE LIGHT RETURN SSE FLOW STARTS AND SOME THIN CIRRUS CLOUDS BY
DAYBREAK. 1027 MB HIGH PRESSURE OVER WESTERN IA INTO NORTHERN MO TO
BY NEAR TAYLORVILLE BY 06Z/1 AM TONIGHT AND INTO THE LOWER OHIO
VALLEY BY DAWN MONDAY. THIS TO LIKELY BRING FROST TO REGION LATER
TONIGHT AND EARLY MON MORNING WITH LIGHT TO CALM WINDS AND CLEAR
SKIES AND LOW DEWPOINTS IN THE LOWER 30S. RECORD LOWS ARE MOSTLY
IN THE LOWER 30S AND CHAMPAIGN COULD GET CLOSE TO THEIR RECORD LOW
OF 33F SET ON SEP 24 1928. NOTE RECORD LOWS FOR SEP 24 BELOW.
HIGH PRESSURE DRIFTS EAST INTO THE MID ATLANTIC STATES BY SUNSET
MON WITH INCREASING MID/HIGH CLOUDS FROM SW TO NE DURING THE DAY
MONDAY. DEVELOPING BREEZY SOUTHERLY FLOW TO WARM UP HIGHS MOSTLY
IN THE LOWER 70S. SERIES OF SHORT WAVES TO EJECT FROM THE CENTRAL
PLAINS INTO CENTRAL/SE IL FROM MON NIGHT INTO THE REST OF THE WORK
WEEK BRINGING CHANCES OF SHOWERS AND THUNDERSTORMS. BEST CHANCES
APPEAR TO BE TUE NIGHT AND ESPECIALLY SOUTHERN AREAS. SPC HAS 5%
RISK OF MARGINAL LARGE HAIL AND GUSTY WINDS ALONG AND SOUTH OF A
RUSHVILLE TO DANVILLE LINE TUE AFTERNOON/EVENING WITH SOME WIND
SHHEAR THOUGH INSTABILITY IS SOMEWHAT LIMITED. TEMPS WARM UP
INTO THE UPPER 70S TO NEAR 80F TUE AND STAY NEAR OR A BIT ABOVE
NORMAL DURING MID WEEK.
LONG TERM...WEDNESDAY THROUGH SUNDAY
BEST CHANCES OF SHOWERS AND THUNDERSTORMS TO SHIFT INTO SOUTHERN
AREAS WED-FRI THOUGH GET A BIT FURTHER NORTH DURING THU NIGHT. NOT
TOO MANY CHANGES MADE TO EXTENDED FORECAST AND HAVE 20-40% CHANCE
OF CONVECTION SAT WITH HIGHEST CHANCES IN SE IL WITH ANOTHER
DISTURBANCE MOVING UP FROM THE SW.
KH
&&
.CLIMATE...
ISSUED 300 PM CDT SUN SEP 23 2012
RECORD LOWS FOR MONDAY MORNING SEP 24...
PEORIA........ 33F IN 1989
SPRINGFIELD... 33F IN 1989
LINCOLN....... 28F IN 1928
BLOOMINGTON... 33F IN 1942
CHAMPAIGN..... 33F IN 1928
DECATUR....... 31F IN 1928
EFFINGHAM..... 28F IN 1928
GALESBURG..... 33F IN 1942
MATTOON....... 30F IN 1928
PALESTINE..... 28F IN 1928
&&
.AVIATION...
ISSUED 1229 PM CDT SUN SEP 23 2012
VFR CONDITIONS WILL PREVAIL THROUGHOUT THE NEXT 24 HOURS.
THE LATEST SURFACE ANALYSIS INDICATED SURFACE HIGH PRESSURE
CENTERED IN WESTERN IA...WITH A RIDGE AXIS EXTENDING SOUTHEAST TO
THE OZARKS. MIXING IN THE LOWER LEVELS OF THE ATMOSPHERE AHEAD OF
THIS RIDGE WAS RESULTING IN OCCASIONAL GUSTS FROM THE NW. THE NAM
BUFKIT FORECAST SOUNDINGS INDICATE THE POTENTIAL FOR GUSTS UP TO
15KTS UNTIL 23-00Z WHEN WE LOSE THE MIXING AND START TO DECOUPLE
THE LOWER ATMOSPHERE. A LITTLE BIT OF MOISTURE EAST OF THE RIDGE
AXIS WILL ALSO RESULT IN FEW TO SCT CUMULUS AROUND 5KFT THIS
AFTERNOON...PARTICULARLY IN EASTERN IL.
THE LATEST NAM AND HRRR BOTH INDICATE THAT THE SURFACE RIDGE AXIS
WILL BE OVER CENTRAL IL LATE THIS EVENING...AND SHIFT EAST OF THE
AREA BY DAYBREAK. LOW LEVEL MIXING WILL ONCE AGAIN DEVELOP BY LATE
MORNING...PRODUCING A S-SSW WIND AROUND 10 KTS BY 15Z. DRY AIR
WILL ONCE AGAIN RESULT IN A CLEAR SKY THROUGH LATE MORNING IN ALL
OF CENTRAL AND EASTERN IL.
MILLER
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY FROM 1 AM TO 8 AM CDT MONDAY FOR ILZ027>031-
036>038-040>057-061>063-066>068-071>073.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1229 PM CDT SUN SEP 23 2012
.DISCUSSION...
ISSUED 1109 AM CDT SUN SEP 23 2012
UPDATED THE FORECAST TO BUMP UP HIGH TEMPERTURES A FEW DEGREES
PARTICULARLY IN WEST CENTRAL IL. PLENTY OF MIXING IS ANTICIPATED...
MOST LIKELY ABOVE 850 MB...BASED ON THE 12Z ILX RAOB. THIS WOULD
RESULT IN HIGHS IN THE MID 60S ACROSS MUCH OF THE FORECAST AREA.
LOW LEVELS WINDS ARE NOT AS STRONG AS YESTERDAY...SO WEST TO
NORTHWEST WINDS OF 10 TO 15 MPH WITH OCCASIONAL GUSTS UP TO 20 MPH
WILL BE RULE. OTHERWISE...EVERYTHING ELSE IN THE CURRENT FORECAST
LOOKS GOOD. WILL BE ANALYZING THE POTENTIAL FOR FROST AGAIN
TONIGHT...ESPECIALLY EAST OF I-55...AND MAY NEED AN ADVISORY FOR
EARLY MONDAY MORNING IF IT APPEARS THAT THE FROST WILL BE
WIDESPREAD ENOUGH.
&&
.AVIATION...
ISSUED 1229 PM CDT SUN SEP 23 2012
VFR CONDITIONS WILL PREVAIL THROUGHOUT THE NEXT 24 HOURS.
THE LATEST SURFACE ANALYSIS INDICATED SURFACE HIGH PRESSURE
CENTERED IN WESTERN IA...WITH A RIDGE AXIS EXTENDING SOUTHEAST TO
THE OZARKS. MIXING IN THE LOWER LEVELS OF THE ATMOSPHERE AHEAD OF
THIS RIDGE WAS RESULTING IN OCCASIONAL GUSTS FROM THE NW. THE NAM
BUFKIT FORECAST SOUNDINGS INDICATE THE POTENTIAL FOR GUSTS UP TO
15KTS UNTIL 23-00Z WHEN WE LOSE THE MIXING AND START TO DECOUPLE
THE LOWER ATMOSPHERE. A LITTLE BIT OF MOISTURE EAST OF THE RIDGE
AXIS WILL ALSO RESULT IN FEW TO SCT CUMULUS AROUND 5KFT THIS
AFTERNOON...PARTICULARLY IN EASTERN IL.
THE LATEST NAM AND HRRR BOTH INDICATE THAT THE SURFACE RIDGE AXIS
WILL BE OVER CENTRAL IL LATE THIS EVENING...AND SHIFT EAST OF THE
AREA BY DAYBREAK. LOW LEVEL MIXING WILL ONCE AGAIN DEVELOP BY LATE
MORNING...PRODUCING A S-SSW WIND AROUND 10 KTS BY 15Z. DRY AIR
WILL ONCE AGAIN RESULT IN A CLEAR SKY THROUGH LATE MORNING IN ALL
OF CENTRAL AND EASTERN IL.
MILLER
&&
.CLIMATE...
ISSUED 200 AM CDT SUN SEP 23 2012
RECORD LOWS FOR MONDAY MORNING...
PEORIA........ 33F IN 1989
SPRINGFIELD... 33F IN 1989
LINCOLN....... 28F IN 1928
BLOOMINGTON... 33F IN 1942
CHAMPAIGN..... 33F IN 1928
DECATUR....... 31F IN 1928
EFFINGHAM..... 28F IN 1928
GALESBURG..... 33F IN 1942
MATTOON....... 30F IN 1928
PALESTINE..... 28F IN 1928
GEELHART
&&
.PREV DISCUSSION...
ISSUED 300 AM CDT SUN SEP 23 2012
EARLY MORNING SURFACE MAP SHOWED HIGH PRESSURE CENTERED OVER
NORTHEAST SOUTH DAKOTA...EXTENDING SOUTHWARD INTO THE MID
MISSISSIPPI VALLEY. SKIES MAINLY CLEAR THE LAST FEW HOURS OVER THE
FORECAST AREA...EXCEPT FOR SOME PATCHY STRATOCUMULUS FROM DECATUR
TO RANTOUL. WINDS IN MANY AREAS HAVE GONE CALM AND ALLOWED
TEMPERATURES TO DIP INTO THE UPPER 30S...WHILE SOME 40S HUNG ON
ESPECIALLY FROM PEORIA SOUTHEAST TO LAWRENCEVILLE...WHERE WINDS
HAVE REMAINED AROUND 5 MPH.
TEMPERATURES MONDAY MORNING REMAIN A CONCERN...ALONG WITH MORE
FROST POTENTIAL. HOWEVER...THE MAIN FORECAST ISSUE WILL BE WITH
PERIODIC SHOWERS AND THUNDERSTORMS...WITH A FRONTAL BOUNDARY THAT
WILL BE DRAPED OVER THE AREA MUCH OF THIS WEEK.
SHORT TERM...TODAY THROUGH TUESDAY...
THE CENTER OF THE HIGH SHOULD BE OVER SOUTHWEST INDIANA BY LATE
EVENING. TEMPERATURES TODAY WILL BE SIMILAR TO THOSE ON
SATURDAY...BUT WILL FEEL MORE PLEASANT WITH MUCH LOWER WIND
SPEEDS. MAIN FOCUS FOR FROST WILL BE ACROSS THE EASTERN CWA
TONIGHT. WILL NEED TO MONITOR THIS AREA FOR ANY ADVISORIES...BUT
WILL LET THE DAY SHIFT HANDLE THAT AFTER EVALUATING WHAT ENDS UP
HAPPENING THIS MORNING FROST-WISE. THERMAL GRADIENT AT 850 MB WILL
BE FOCUSING ALONG THE MISSISSIPPI RIVER LATE TONIGHT AND WILL MOVE
THROUGH THE CWA ON MONDAY. THE WARMER SURFACE TEMPS WILL BE ACROSS
THE WESTERN CWA...AS 850 MB TEMPS RISE TO +14C.
ANOTHER SURGE OF WARM AIR ALOFT WILL PUSH THROUGH THE CWA MONDAY
NIGHT...AS SOME ELEVATED CONVECTION DEVELOPS OUT IN MISSOURI
ALONG ANOTHER DEVELOPING FRONT...BEFORE SHIFTING EASTWARD INTO
ILLINOIS. CENTRAL AND SOUTHERN CWA APPEAR MORE LIKELY TO SEE SOME
OF THIS ARRIVE BY TUESDAY MORNING. MEANWHILE...THE MAIN COLD FRONT
WILL BE DROPPING SOUTHWARD ON TUESDAY...AS ANOTHER WAVE SWINGS
THROUGH THE UPPER GREAT LAKES IN ASSOCIATION WITH THE BROAD TROUGH
THAT HAS BEEN IN PLACE FOR SEVERAL DAYS NOW. MUCH OF THE CWA WILL
BE IN THE WARM SECTOR TUESDAY...ALLOWING CAPES TO RISE TO AROUND
1500 J/KG...SUPPORTING CONTINUED THUNDERSTORM CHANCES. MAY SEE
SOME STORMS WITH HAIL AND GUSTY WINDS...BUT SEVERE THREAT APPEARS
RELATIVELY LOW...WITH 5 PERCENT CHANCES MENTIONED IN THE LATEST
SPC DAY3 OUTLOOK. WILL CARRY THE HIGHEST RAIN CHANCES TUESDAY
NIGHT.
LONG TERM...WEDNESDAY THROUGH SATURDAY...
MAIN QUESTION IS HOW FAR THIS FRONT WILL MAKE IT...AS IT WILL
BECOME SANDWICHED BETWEEN THE NORTHERN AND SOUTHERN BRANCHES OF
THE JET STREAM. MOST OF THE EVENING MODELS HAVE IT GENERALLY ALONG
AN WEST-EAST AXIS CENTERED NEAR THE I-72 CORRIDOR BY WEDNESDAY
MORNING...THEN REACHING THE OHIO RIVER AREA TOWARD LATE EVENING AS
HIGH PRESSURE BUILDS INTO THE GREAT LAKES. THE NOTABLE EXCEPTION
IS THE GFS MODEL...WHICH KEEPS IT OVER CENTRAL ILLINOIS UNTIL A
DEVELOPING SURFACE LOW ARRIVES FRIDAY MORNING. THAT SOLUTION KEEPS
PERIODIC RAIN CHANCES GOING THROUGH FRIDAY...WHEREAS THE
ECMWF/CANADIAN SOLUTIONS WOULD LIKELY BRING DRY WEATHER TO THE
NORTHERN CWA FOR A GOOD PORTION OF THIS PERIOD. FOR THIS
FORECAST...WILL SLOWLY SPREAD THE SLIGHT CHANCE POPS SOUTHWARD
THROUGH THURSDAY...BEFORE BRINGING THEM BACK UP THURSDAY NIGHT
INTO THE 30-40 PERCENT RANGE AS A SHORTWAVE APPROACHES FROM THE
WEST IN THE SOUTHERN JET STREAM. ONCE THIS PARTICULAR WAVE CLEARS
THE AREA ON FRIDAY...DRY WEATHER IS EXPECTED AS THE WEEKEND
BEGINS.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1015 PM EDT MON SEP 24 2012
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 331 PM EDT MON SEP 24 2012
WARM ADVECTION WILL RAMP UP TONIGHT AND BRING WARMER TEMPERATURES TO
THE AREA. CHANCES FOR RAIN AND THUNDERSTORMS WILL ALSO ARRIVE LATE
TONIGHT WITH AN UPPER WAVE APPROACHING THE AREA. OVER THE COMING
DAYS A FRONT WILL STALL ACROSS CENTRAL INDIANA AND WAVES WILL MOVE
ALONG THIS FRONT KEEPING PRECIPITATION IN THE FORECAST FOR PARTS OF
THE AREA THROUGHOUT THE PERIOD. WITH COLDER AIR BOTTLED BACK UP TO
THE NORTH EXPECT TEMPERATURES TO BE CLOSE TO NORMAL FOR THIS TIME OF
YEAR.
&&
.NEAR TERM /REST OF TONIGHT/...
ISSUED AT 958 PM EDT MON SEP 24 2012
CUT OUT ALL POPS PRIOR TO 09Z...AND CUT POPS AFTER 09Z TO NO MORE
THAN 45 AND CONFINED ONLY TO SW HALF OF FORECAST AREA.
VERY DRY IN THE LOW LEVELS RIGHT NOW...AND THIS IS THE CASE ALL
THE WAY BACK INTO THE MID MISSISSIPPI VALLEY PER 00Z RAOBS. HAVING
A VERY HARD TIME SEEING CURRENT MID 30S TO LOW 40S DEWPOINTS
MOISTENING UP ENOUGH FOR MORE THAN A CHANCE OF PRECIP LATE.
A LOW LEVEL JET AXIS DOES RAMP UP TO OUR SW LATER TONIGHT...BUT
NEVER QUITE MAKES IT TO THE AREA PRIOR TO 12Z...AND WILL BE
ADVECTING A FAIRLY DRY AIRMASS ACCORDING TO AFOREMENTIONED RAOBS.
THIS ALSO REQUIRED A CUT TO OVERNIGHT LOWS AS WELL...AS LOWER THAN
EXPECTED DEWPOINTS AND LATER CLOUD COVER/POSSIBLE PRECIP WILL
ALLOW TEMPS TO DROP INTO THE UPPER 40S TO AROUND 50. MAV GUIDANCE
APPEARS TO HANDLE THIS WELL AND WAS USED.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
ISSUED AT 331 PM EDT MON SEP 24 2012
FORECAST FOCUS IS ON POPS. TUESDAY STARTS OUT WITH A LOW LEVEL JET
POINTING AT AND THEN TRAVERSING CENTRAL INDIANA. THIS WILL BRING
ISENTROPIC LIFT ACROSS THE AREA AND ALONG WITH A SHORTWAVE MOVING
ACROSS THE STATE SHOULD BE PLENTY OF FORCING FOR PRECIP. WENT HIGHER
WITH POPS IN SOME PLACES TO KEEP LIKELY GOING ACROSS THE AREA AND
INCLUDED CHANCES FOR THUNDERSTORMS BASED ON INCREASING ELEVATED
INSTABILITY. WITH ELEVATED INSTABILITY AND LOW END SHEAR IN PLACE
COULD SEE SOME MARGINAL HAIL. PRECIPITATION CHANCES LOOK EVEN BETTER
FOR TUESDAY NIGHT WITH A LOW LEVEL JET INCREASING IN STRENGTH AND
SETTING UP JUST TO THE SOUTHWEST. LOOKS LIKE ANOTHER SHORTWAVE WILL
BE MOVING THROUGH AND A FRONT WILL BE SAGGING SOUTH INTO THE AREA.
WITH THESE FEATURES COMBINING INCREASED GUIDANCE POPS TO CATEGORICAL
ACROSS ALL BUT THE NORTH. ON WEDNESDAY KEPT LIKELY POPS GOING SOUTH
OF THE FRONT AND KEPT HIGH CHANCE POPS IN THE SOUTHERN COUNTIES FOR
WEDNESDAY NIGHT WITH THE FRONT STALLING OUT NEAR OR JUST SOUTH OF
THERE. WITH GOOD INSTABILITY SHOWING UP FROM TUESDAY THROUGH
WEDNESDAY KEPT CHANCE FOR THUNDER GOING...DECREASING TO A SLIGHT
CHANCE FOR THUNDER WEDNESDAY NIGHT AND THURSDAY AS FRONT MAY BE
SOUTH OF THE AREA.
FOR TEMPERATURES...GENERALLY FAVORED WARMER GUIDANCE AT NIGHT WITH
WARM ADVECTION...RAIN...AND CLOUD COVER. FOR DAYTIME HIGHS USED A
GUIDANCE AVERAGE.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
ISSUED AT 216 PM EDT MON SEP 23 2012
MAIN FOCUS WITH THE EXTENDED WITH BE POPS AND TEMPERATURES. MODELS
ARE NOW IN A BIT CLOSER AGREEMENT ON SLIDING AN UPPER TROUGH
SOUTHEAST ACROSS THE OHIO VALLEY LATE IN THE WEEKEND AND EARLY NEXT
WEEK AS IT PHASES WITH THE PERSISTENT EASTERN CANADIAN VORTEX. THIS
SHOULD KEEP THE MIDWEEK FRONT WELL SOUTH OF CENTRAL INDIANA ACROSS
THE SOUTHERN STATES THROUGH THE EXTENDED. HOWEVER...HPC IS
SUGGESTING A SECONDARY FRONT MAY MOVE THROUGH THE AREA FRIDAY
NIGHT..AND SEVERAL UPPER WAVES WILL DROP SOUTHEAST ACROSS THE OHIO
VALLEY IN NORTHWEST FLOW ON THE BACK SIDE OF THE TROUGH.
SO...DESPITE THE MODELS ALL GOING WITH LITTLE TO ANY QPF AFTER
FRIDAY...WILL GENERALLY ACCEPT THE LOW POPS FOR MOST PERIODS FROM
THE CENTRAL REGION INITIALIZATION. MODEL TO MODEL AND MODEL VERSUS
MODEL CONSISTENCY HAS JUST NOT BEEN GOOD ENOUGH TO DEVIATE MUCH AWAY
FROM THEM IN EITHER POPS OR TEMPERATURES. WITH THAT IN MIND...WILL
STICK WITH THE SLIGHTLY BELOW TEMPERATURES AS WELL FROM THE CR INIT.
&&
.AVIATION /DISCUSSION FOR 250300Z TAF UPDATE/...
ISSUED AT 1015 PM EDT MON SEP 24 2012
WARM ADVECTION AND LOW LEVEL JET NOSING INTO THE LOWER OHIO VALLEY
ASSISTING IN STRATOCU DEVELOPMENT AROUND 5KFT OVER SOUTHEAST
ILLINOIS CURRENTLY. RAP HAS A NICE HANDLE ON THIS EXPANDING INTO THE
TERMINALS BETWEEN 04-06Z. HAVE PULLED VCSH MENTION FOR THE OVERNIGHT
AS ANOTHER LOOK AT MODEL SOUNDINGS AND 00Z RAOBS TO THE SOUTHWEST
INDICATE AN ABUNDANCE OF DRY AIR THROUGH THE LOWER LEVELS. OUTSIDE
OF A FEW SPRINKLES...THINK ANY APPRECIABLE RAINFALL WILL HOLD OFF
UNTIL BETTER FORCING ARRIVES NEAR DAYBREAK.
00Z DISCUSSION FOLLOWS.
VFR CONDITIONS EXPECTED TONIGHT...POSSIBLE PERIODS OF MVFR
CONDITIONS TUESDAY MORNING.
CENTRAL INDIANA REMAINS UNDER THE INFLUENCE OF HIGH PRESSURE
DEPARTING OFF TO THE EAST. CLOUDS WILL BE ON A SLOW INCREASE THIS
EVENING AS WARM ADVECTION RAMPS UP OVER THE MID MISSISSIPPI
VALLEY. CEILINGS WILL REMAIN ABOVE 10KFT THROUGH 06Z WITH
MOISTENING OF THE BOUNDARY LAYER BETWEEN 06 AND 12Z AS FORCING
ALOFT...ISENTROPIC LIFT AND A LOW LEVEL JET TRANSPORT LOW LEVEL
MOISTURE INTO THE REGION. WILL CONTINUE WITH VCSH MENTION AFTER
06Z AT ALL TERMINALS AS RAIN INCREASES IN COVERAGE TOWARDS
DAYBREAK. MODEL SOUNDINGS SHOWING SOME ELEVATED INSTABILITY SO
COULD SEE A FEW LIGHTNING STRIKES...HOWEVER NOT ANTICIPATING
WIDESPREAD THUNDERSTORMS PRIOR TO 12Z.
WIDESPREAD CONVECTION TO IMPACT THE TERMINALS TUESDAY MORNING AS
MID LEVEL SHORTWAVE MOVES THROUGH THE REGION. POTENTIAL FOR
CEILINGS TO DIP INTO MVFR CATEGORY WITHIN HEAVIER PRECIP DURING
THE MORNING. ANY CONVECTION LIKELY TO BE MORE SCATTERED IN
COVERAGE DURING THE AFTERNOON AS ADDITIONAL DISTURBANCES ALOFT
TRACK THROUGH THE REGION. HAVE HELD ONTO VCTS MENTION ALL DAY WITH
UNSTABLE AIRMASS PRESENT. S/SW WINDS AROUND 10KTS ANTICIPATED ON
TUESDAY.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...CP
NEAR TERM...NIELD
SHORT TERM...CP
LONG TERM....MK
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
136 AM CDT SUN SEP 23 2012
...UPDATED SYNOPSIS...
.SYNOPSIS...
ISSUED AT 135 AM CDT SUN SEP 23 2012
A DEEP UPPER LEVEL CYCLONE WAS CENTERED SOUTH OF JAMES BAY, AND AN
UPPER LEVEL RIDGE EXTENDED FROM AN ANTICYCLONE IN SOUTHEAST NEW
MEXICO TO THE NORTHWEST TERRITORIES. A COMPACT UPPER LEVEL LOW
PRESSURE SYSTEM WAS DIGGING INTO WESTERN WASHINGTON BENEATH THE
CANADIAN RIDGE. A WEAK SUBTROPICAL JET WAS EVIDENT ON SATELLITE
IMAGERY FROM THE DEEP TROPICS TO SOUTHERN CALIFORNIA, AND
ABUNDANT HIGH LEVEL TROPICAL MOISTURE WAS FLOWING FROM THE SOUTH
PACIFIC AROUND A WEAK UPPER LEVEL TROUGH NEAR 32N/122W INTO THE
SOUTHWESTERN UNITED STATES. AT THE SURFACE, A LARGE CANADIAN HIGH
PRESSURE SYSTEM CENTERED IN THE EASTERN DAKOTAS COVERED MUCH OF THE
EASTERN UNITED STATES. TEMPERATURES AT 06Z IN THE COLD AIR WERE NEAR
OR BELOW FREEZING IN THE EASTERN DAKOTAS, NORTHERN IOWA AND
MINNESOTA. A STATIONARY FRONT EXTENDED FROM EASTERN COLORADO ACROSS
THE TEXAS PANHANDLE TO NORTH TEXAS. VERY WARM AIR WAS EVIDENT SOUTH
OF THE STATIONARY FRONT WITH H8 TEMPERATURES IN THE MID 20SC IN WEST
TEXAS AND THE TEXAS PANHANDLE. EAST TO SOUTHEAST LOW LEVEL FLOW
PREVAILED NORTH OF THE FRONT ACROSS WESTERN KANSAS.
A MID LEVEL DEFORMATION ZONE BETWEEN THE FLOW AROUND THE DEEP
CYCLONE IN ONTARIO AND INCREASING WESTERLY FLOW ACROSS THE ROCKIES
WAS RESULTING IN FRONTOGENESIS IN A BAND FROM EASTERN COLORADO
ACROSS SOUTHWEST KANSAS INTO NORTHWEST OKLAHOMA. WEAK MID LEVEL
INSTABILITY (CAPE VALUES AS MUCH AS 300 JOULES/KG) WAS BEING TAPPED
BY THE UPWARD VERTICAL MOTION IN THE FRONTOGENETIC REGION TO SUPPORT
DEVELOPMENT OF SHOWERS AND A FEW THUNDERSTORMS.
&&
.UPDATE...
ISSUED AT 930 PM CDT SAT SEP 22 2012
THE FORECAST WAS UPDATED TO INCLUDE A SLIGHT CHANCE OF SHOWERS
WITH AN ISOLATED THUNDERSTORM MAINLY 06Z-15Z...TIED TO A NORTHWEST
TO SOUTHEAST AXIS OF LOWER-MID LEVEL FRONTOGENESIS (PARTICULARLY
800-700MB LAYER). LATEST NAM12 MODEL SOLUTION SUGGESTS 150-300
J/KG OF MUCAPE WITHIN THE ZONE OF STRONGEST WARM FRONTOGENESIS A
750MB...FROM TRIBUNE TO GARDEN CITY TO ASHLAND...SO A FEW
LIGHTNING STRIKES WILL ALSO BE POSSIBLE. THE 3KM HRRR HAS SHOWN A
RUN-TO-RUN CONSISTENCY IN GENERATING SHOWERS ALONG THIS
FRONTOGENETIC ZONE. SHOWERS WILL SHIFT TO THE EAST BY DAYBREAK
INTO SOUTH CENTRAL KS/NORTH CENTRAL OK WITH POPS DIMINISHING IN
THE GRIDS BY MID-MORNING SUNDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 248 PM CDT SAT SEP 22 2012
THE MAIN FORECAST CHALLENGES ARE INCREASING CLOUDS TONIGHT AND A FEW
SPRINKLES, THEN HIGH TEMPERATURES ON SUNDAY AHEAD OF A WARM FRONT.
MODELS IN AGREEMENT WITH MOVING A COLD UPPER LEVEL TROUGH SLOWLY
EASTWARD ACROSS THE UPPER MIDWEST INTO SUNDAY WITH NORTHWEST FLOW
ALOFT CONTINUING OVER THE CENTRAL PLAINS. AS THE UPPER TROUGH
MOVES EAST, A RIDGE OF COOLER SURFACE HIGH PRESSURE WILL SLOWLY
PROGRESS EASTWARD FROM THE MISSOURI VALLEY INTO THE MID
MISSISSIPPI VALLEY ALLOWING A WARM FRONT TO PUSH NORTH INTO
EASTERN COLORADO TO JUST SOUTH OF ELKHART AND INTO CENTRAL
OKLAHOMA ON SUNDAY AFTERNOON. MID AND UPPER LEVEL MOISTURE AND
CLOUDINESS IS ALSO FORECAST TO INCREASE AROUND AND AFTER MIDNIGHT
ACROSS WESTERN KANSAS AS WEAK 800-700MB FRONTOGENESIS AND
ISENTROPIC LIFT EVOLVE ALOFT AHEAD OF THE SURFACE WARM FRONT. DEEP
MOISTURE AND CAPE ARE LACKING FOR ELEVATED THUNDERSTORMS, HOWEVER
COULD BE ENOUGH LIFT FOR SOME LIGHT SHOWERS OR SPRINKLES MAINLY IN
THE FORM OF VIRGA. WILL KEEP A SILENT POP GOING AFTER MIDNIGHT
TONIGHT WITH INCREASING CLOUDINESS.
FOR TONIGHT LOOK FOR INCREASING CLOUDINESS WITH SOUTHEAST WINDS
DECREASING TO 10 TO 15 MPH. OVERNIGHT LOWS WILL RANGE FROM THE LOWER
40S FROM DIGHTON TO SAINT JOHN AND NORTH TO THE MID AND UPPER 40S
ELSEWHERE. THESE TEMPS ARE A FEW DEGREES WARMER THAN CURRENT
GUIDANCE DUE TO CLOUDINESS EXPECTED. THEN FOR SUNDAY, MODELS
CONTINUE TO SHOW INCREASING UPPER LEVEL MOISTURE IN THE FORM OF
CIRRUS CLOUDS. HIGH TEMPERATURES WERE LOWERED A FEW DEGREES FROM
PREVIOUS FORECAST WITH EXPECTED HIGH LEVEL CLOUDINESS AND
SOUTHEASTERLY UPSLOPE FLOW AHEAD OF THE WARM FRONT. WINDS LOOK TO
INCREASE TO 15 TO 25 MPH BY LATE MORNING INTO THE AFTERNOON WITH
HIGHS FROM THE MID 70S NORTH OF A GARDEN CITY TO DODGE CITY TO
MEDICINE LODGE LINE AND WARMER LOW TO MID 80S SOUTH.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 329 PM CDT SAT SEP 22 2012
FORECAST CHALLENGES LIE AHEAD THROUGH THE MIDDLE OF THE WEEK WITH
REGARD TO PRECIPITATION AND CONVECTIVE CHANCES AND TO A LESSER
EXTENT TEMPERATURES.
WARMER OVERNIGHT LOWS WILL BE EXPECTED ON SUNDAY NIGHT AS A BETTER
AS WARMER BOUNDARY LAYER AIR ADVECTS INTO SW KANSAS AHEAD OF THE
EASTERN COLORADO TROUGH AND PANHANDLES SURFACE LOW. MONDAY SHOULD
REMAIN DRY AND WARMING ACROSS THE SOUTHERN HALF OF WESTERN KANSAS.
SOUTH CENTRAL KANSAS COULD BE THE WARMEST INTO TUESDAY, AS A SURFACE
LOW REMAINS QUASI-STATIONARY OR SLOWLY EAST DURING THE TIMEFRAME.
ALTHOUGH THE ATMOSPHERE WOULD BE CONDITIONALLY UNSTABLE, THE LOW`
CONVERGENCE REGIONS IN AND OF ITSELF MIGHT NOT BE ENOUGH TO SET OFF
SHOWERS AND THUNDERSTORMS. A BETTER CATALYST APPEARS IN THE MODELS
IN THE FORM OF SHORTWAVES BEGINNING AS EARLY AS TUESDAY OR TUESDAY
EVENING. WEAK LOW AMPLITUDE TROUGHING WILL REMAIN IN PLACE OVER THE
WESTERN STATES AND INTO THE CENTRAL ROCKIES DURING THIS PERIOD WHICH
WILL ALLOW OPPORTUNITIES FOR MULTIPLE SHORTWAVE IMPULSES TO INFLUENCE
WESTERN AND CENTRAL KANSAS. BY THE MIDDLE OF THE WEEKEND, NEGATIVE
VORTICITY ADVECTION AND INCREASED SUBSIDENCE SHOULD BEGIN TO
MAKE AN IMPACT AND ELIMINATE CHANCES FOR SHOWERS OR STORMS.
TEMPERATURES WILL REMAIN SEASONAL THROUGH THE PERIOD, GENERALLY IN
THE LOW 80S TO UPPER 70S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1258 AM CDT SUN SEP 23 2012
A LARGE CANADIAN HIGH PRESSURE SYSTEM WILL CONTINUE TO BUILD
SOUTHWARD FROM THE EASTERN DAKOTAS TO KENTUCKY BY MONDAY MORNING. A
TROUGH OF LOW PRESSURE WILL DEEPEN IN THE LEE OF THE ROCKIES TODAY.
A STATIONARY FRONT EXTENDING FROM SOUTHEAST COLORADO ACROSS THE
TEXAS PANHANDLE TO EXTREME NORTHERN TEXAS WILL BEGIN TO MOVE NORTH
AS A WARM FRONT TONIGHT AND WILL EXTEND FROM FROM NEAR ELKHART TO
EAST CENTRAL OKLAHOMA BY MONDAY MORNING.
MID LEVEL FRONTOGENESIS WILL SUPPORT CONTINUED DEVELOPMENT OF
SCATTERED SHOWERS IN SOUTHWEST KANSAS EARLY THIS MORNING. SHOWERS
WILL BE IN THE VICINITY OF GCK AND DDC FROM 07Z THROUGH 12Z BUT WILL
WEAKEN AND MOVE OFF TO THE SOUTHEAST AFTER 12Z. THE SHOWERS WILL BE
LIGHT AND WILL NOT RESULT IN SIGNIFICANT VISIBILITY RESTRICTIONS.
BROKEN CLOUDS WITH BASES AOA 100 WILL PREVAIL EARLY THIS MORNING
IMPROVING TO ONLY A FEW CLOUDS AOA 150 BY LATE MORNING. SOUTHEAST
WINDS 10 TO 15 KNOTS WILL PREVAIL THROUGH THE DAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 76 53 83 62 / 10 0 0 0
GCK 76 52 83 58 / 10 0 0 10
EHA 85 59 89 60 / 10 0 0 10
LBL 84 56 89 62 / 10 0 0 10
HYS 74 52 76 55 / 10 0 0 10
P28 76 56 92 66 / 20 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...UMSCHEID
SYNOPSIS...RUTHI
SHORT TERM...KRUSE
LONG TERM...RUSSELL
AVIATION...RUTHI
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
100 AM CDT SUN SEP 23 2012
...UPDATED AVIATION SECTION...
.UPDATE...
ISSUED AT 930 PM CDT SAT SEP 22 2012
THE FORECAST WAS UPDATED TO INCLUDE A SLIGHT CHANCE OF SHOWERS
WITH AN ISOLATED THUNDERSTORM MAINLY 06Z-15Z...TIED TO A NORTHWEST
TO SOUTHEAST AXIS OF LOWER-MID LEVEL FRONTOGENESIS (PARTICULARLY
800-700MB LAYER). LATEST NAM12 MODEL SOLUTION SUGGESTS 150-300
J/KG OF MUCAPE WITHIN THE ZONE OF STRONGEST WARM FRONTOGENESIS A
750MB...FROM TRIBUNE TO GARDEN CITY TO ASHLAND...SO A FEW
LIGHTNING STRIKES WILL ALSO BE POSSIBLE. THE 3KM HRRR HAS SHOWN A
RUN-TO-RUN CONSISTENCY IN GENERATING SHOWERS ALONG THIS
FRONTOGENETIC ZONE. SHOWERS WILL SHIFT TO THE EAST BY DAYBREAK
INTO SOUTH CENTRAL KS/NORTH CENTRAL OK WITH POPS DIMINISHING IN
THE GRIDS BY MID-MORNING SUNDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 248 PM CDT SAT SEP 22 2012
THE MAIN FORECAST CHALLENGES ARE INCREASING CLOUDS TONIGHT AND A FEW
SPRINKLES, THEN HIGH TEMPERATURES ON SUNDAY AHEAD OF A WARM FRONT.
MODELS IN AGREEMENT WITH MOVING A COLD UPPER LEVEL TROUGH SLOWLY
EASTWARD ACROSS THE UPPER MIDWEST INTO SUNDAY WITH NORTHWEST FLOW
ALOFT CONTINUING OVER THE CENTRAL PLAINS. AS THE UPPER TROUGH
MOVES EAST, A RIDGE OF COOLER SURFACE HIGH PRESSURE WILL SLOWLY
PROGRESS EASTWARD FROM THE MISSOURI VALLEY INTO THE MID
MISSISSIPPI VALLEY ALLOWING A WARM FRONT TO PUSH NORTH INTO
EASTERN COLORADO TO JUST SOUTH OF ELKHART AND INTO CENTRAL
OKLAHOMA ON SUNDAY AFTERNOON. MID AND UPPER LEVEL MOISTURE AND
CLOUDINESS IS ALSO FORECAST TO INCREASE AROUND AND AFTER MIDNIGHT
ACROSS WESTERN KANSAS AS WEAK 800-700MB FRONTOGENESIS AND
ISENTROPIC LIFT EVOLVE ALOFT AHEAD OF THE SURFACE WARM FRONT. DEEP
MOISTURE AND CAPE ARE LACKING FOR ELEVATED THUNDERSTORMS, HOWEVER
COULD BE ENOUGH LIFT FOR SOME LIGHT SHOWERS OR SPRINKLES MAINLY IN
THE FORM OF VIRGA. WILL KEEP A SILENT POP GOING AFTER MIDNIGHT
TONIGHT WITH INCREASING CLOUDINESS.
FOR TONIGHT LOOK FOR INCREASING CLOUDINESS WITH SOUTHEAST WINDS
DECREASING TO 10 TO 15 MPH. OVERNIGHT LOWS WILL RANGE FROM THE LOWER
40S FROM DIGHTON TO SAINT JOHN AND NORTH TO THE MID AND UPPER 40S
ELSEWHERE. THESE TEMPS ARE A FEW DEGREES WARMER THAN CURRENT
GUIDANCE DUE TO CLOUDINESS EXPECTED. THEN FOR SUNDAY, MODELS
CONTINUE TO SHOW INCREASING UPPER LEVEL MOISTURE IN THE FORM OF
CIRRUS CLOUDS. HIGH TEMPERATURES WERE LOWERED A FEW DEGREES FROM
PREVIOUS FORECAST WITH EXPECTED HIGH LEVEL CLOUDINESS AND
SOUTHEASTERLY UPSLOPE FLOW AHEAD OF THE WARM FRONT. WINDS LOOK TO
INCREASE TO 15 TO 25 MPH BY LATE MORNING INTO THE AFTERNOON WITH
HIGHS FROM THE MID 70S NORTH OF A GARDEN CITY TO DODGE CITY TO
MEDICINE LODGE LINE AND WARMER LOW TO MID 80S SOUTH.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 329 PM CDT SAT SEP 22 2012
FORECAST CHALLENGES LIE AHEAD THROUGH THE MIDDLE OF THE WEEK WITH
REGARD TO PRECIPITATION AND CONVECTIVE CHANCES AND TO A LESSER
EXTENT TEMPERATURES.
WARMER OVERNIGHT LOWS WILL BE EXPECTED ON SUNDAY NIGHT AS A BETTER
AS WARMER BOUNDARY LAYER AIR ADVECTS INTO SW KANSAS AHEAD OF THE
EASTERN COLORADO TROUGH AND PANHANDLES SURFACE LOW. MONDAY SHOULD
REMAIN DRY AND WARMING ACROSS THE SOUTHERN HALF OF WESTERN KANSAS.
SOUTH CENTRAL KANSAS COULD BE THE WARMEST INTO TUESDAY, AS A SURFACE
LOW REMAINS QUASI-STATIONARY OR SLOWLY EAST DURING THE TIMEFRAME.
ALTHOUGH THE ATMOSPHERE WOULD BE CONDITIONALLY UNSTABLE, THE LOW`
CONVERGENCE REGIONS IN AND OF ITSELF MIGHT NOT BE ENOUGH TO SET OFF
SHOWERS AND THUNDERSTORMS. A BETTER CATALYST APPEARS IN THE MODELS
IN THE FORM OF SHORTWAVES BEGINNING AS EARLY AS TUESDAY OR TUESDAY
EVENING. WEAK LOW AMPLITUDE TROUGHING WILL REMAIN IN PLACE OVER THE
WESTERN STATES AND INTO THE CENTRAL ROCKIES DURING THIS PERIOD WHICH
WILL ALLOW OPPORTUNITIES FOR MULTIPLE SHORTWAVE IMPULSES TO INFLUENCE
WESTERN AND CENTRAL KANSAS. BY THE MIDDLE OF THE WEEKEND, NEGATIVE
VORTICITY ADVECTION AND INCREASED SUBSIDENCE SHOULD BEGIN TO
MAKE AN IMPACT AND ELIMINATE CHANCES FOR SHOWERS OR STORMS.
TEMPERATURES WILL REMAIN SEASONAL THROUGH THE PERIOD, GENERALLY IN
THE LOW 80S TO UPPER 70S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1258 AM CDT SUN SEP 23 2012
A LARGE CANADIAN HIGH PRESSURE SYSTEM WILL CONTINUE TO BUILD
SOUTHWARD FROM THE EASTERN DAKOTAS TO KENTUCKY BY MONDAY MORNING. A
TROUGH OF LOW PRESSURE WILL DEEPEN IN THE LEE OF THE ROCKIES TODAY.
A STATIONARY FRONT EXTENDING FROM SOUTHEAST COLORADO ACROSS THE
TEXAS PANHANDLE TO EXTREME NORTHERN TEXAS WILL BEGIN TO MOVE NORTH
AS A WARM FRONT TONIGHT AND WILL EXTEND FROM FROM NEAR ELKHART TO
EAST CENTRAL OKLAHOMA BY MONDAY MORNING.
MID LEVEL FRONTOGENESIS WILL SUPPORT CONTINUED DEVELOPMENT OF
SCATTERED SHOWERS IN SOUTHWEST KANSAS EARLY THIS MORNING. SHOWERS
WILL BE IN THE VICINITY OF GCK AND DDC FROM 07Z THROUGH 12Z BUT WILL
WEAKEN AND MOVE OFF TO THE SOUTHEAST AFTER 12Z. THE SHOWERS WILL BE
LIGHT AND WILL NOT RESULT IN SIGNIFICANT VISIBILITY RESTRICTIONS.
BROKEN CLOUDS WITH BASES AOA 100 WILL PREVAIL EARLY THIS MORNING
IMPROVING TO ONLY A FEW CLOUDS AOA 150 BY LATE MORNING. SOUTHEAST
WINDS 10 TO 15 KNOTS WILL PREVAIL THROUGH THE DAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 53 83 62 86 / 0 0 0 10
GCK 52 83 58 84 / 0 0 10 10
EHA 59 89 60 87 / 0 0 10 10
LBL 56 89 62 87 / 0 0 10 10
HYS 52 76 55 82 / 0 0 10 10
P28 56 92 66 90 / 0 0 0 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...UMSCHEID
SHORT TERM...KRUSE
LONG TERM...RUSSELL
AVIATION...RUTHI
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
134 PM EDT SUN SEP 23 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 534 AM EDT SUN SEP 23 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A DEEP TROF OVER THE GREAT
LAKES REGION. LAST SIGNIFICANT SHORTWAVE ROTATING THRU TROF PASSED
ACROSS UPPER MI LATE YESTERDAY AFTN/EARLY EVENING...PROVIDING A GOOD
BOOST TO LAKE EFFECT PCPN. UNDER DEEP CYCLONIC FLOW/DEEP MOISTURE
(UPSTREAM 00Z CWPL SOUNDING SHOWED SATURATION TO 700MB) AND 850MB
TEMPS OF -2 TO -4C PER LATEST RUC ANALYSIS...LAKE EFFECT SHRA
CONTINUE WITHIN GENERAL NNW WIND FLOW. DESPITE DEEP
MOISTURE/FAVORABLE OVERWATER INSTABILITY...SHRA COVERAGE IS A LITTLE
LESS THAN EXPECTED. HOWEVER...DEEP CONVECTION/MOISTURE IS NO DOUBT
LEADING TO SOME BRIEF HVY RAINFALL/GRAUPEL WITH SOME OF THE SHRA.
MID/UPPER TROF OVER THE GREAT LAKES WILL BEGIN TO SHIFT E TODAY...
RESULTING IN RISING HEIGHTS. AT THE LOWER LEVELS...THE UPPER LAKES
WILL REMAIN FIRMLY WITHIN THE THERMAL TROF. WITH MORNING 850MB TEMPS
OF -2 TO -4C ONLY RISING TO 0 TO -2C BY LATE AFTN...LAKE EFFECT -SHRA
WILL CONTINUE THRU THE DAY. HOWEVER...RISING HEIGHTS ALONG WITH
ADVECTION OF DRIER AIR AT THE LOW LEVELS AS WINDS BACK MORE WESTERLY
WILL SPELL DIMINISHING SHRA FROM W TO E THRU THE DAY. BEING VERY
EARLY IN THE LAKE EFFECT SEASON...DIURNAL HEATING WILL ALSO DISRUPT
LAKE EFFECT PROCESSES THIS AFTN...AIDING THE DIMINISHING TREND.
SO...EXPECT LINGERING NW FLOW LAKE EFFECT SHRA OVER THE W TO END BY
EARLY AFTN. OVER THE E...LAKE EFFECT SHRA WILL DECREASE IN
COVERAGE...BUT PROBABLY NOT END UNTIL LATER THIS EVENING WHEN WINDS
BACK TO AN OFFSHORE DIRECTION. GIVEN VIGOROUS CONVECTION/DEEP CLOUD
DEPTH THIS MORNING...HEAVIER SHRA WILL CONTINUE TO MIX WITH GRAUPEL
AT TIMES.
WAA REGIME RAMPS UP ON WESTERLY WINDS TONIGHT AHEAD OF THE NEXT
SHORTWAVE TROF WHICH WILL BE DROPPING S TOWARD THE UPPER LAKES.
BEFORE HIGH CLOUDS ARRIVE AHEAD OF APPROACHING SHORTWAVE AND BEFORE
LOW-LEVEL WINDS BEGIN TO INCREASE SUBSTANTIALLY...TEMPS WILL HAVE AN
OPPORTUNITY TO FALL QUICKLY THIS EVENING UNDER DRY AIR MASS
(PRECIPITABLE WATER 50-60PCT OF NORMAL). FAVORED THE LOWER SIDE OF
GUIDANCE GIVEN THE COOL AFTN TODAY. TEMPS WILL PROBABLY SLIP BLO
FREEZING ACROSS A GOOD PORTION OF THE FCST AREA WELL INLAND FROM
LAKE SUPERIOR. TEMPS SHOULD BEGIN TO RISE SLOWLY OVERNIGHT AS
CLOUDS/WINDS INCREASE.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 534 AM EDT SUN SEP 23 2012
UPPER TROUGH THAT HAS BEEN PROVIDING THE COOL AND WET CONDITIONS
OVER THE LAST WEEK WILL HAVE SHIFTED EAST BY THE START OF THE
PERIOD. BUT...A SECONDARY WAVE WILL DROP S TOWARDS THAT AREA MON
AFTN AND THROUGH THE UPPER GREAT LAKES MON NIGHT. A SFC HIGH TO THE
S AND APPROACHING TROUGH/SHORTWAVE WILL LEAD TO STRONG SW LLVL
JET OVER THE CWA AT THE START OF THE LONG TERM PERIOD. WIND GUSTS
FOR MON WILL DEPEND ON HOW QUICKLY AREA CAN MIX INTO THE STRONGER
WINDS ALOFT...SINCE LLVL JET WILL QUICKLY SHIFT SE THROUGH THE DAY.
STRONGEST WINDS WILL BE OVER WRN LK SUPERIOR AND FAR WRN UPPER
MI...CLOSEST TO THE TIGHTENING PRESSURE GRADIENT. WITH H925-850
WINDS DURING THE MORNING IN THE 40-50KT RANGE WOULD THINK
EXPOSED...HIGHER TERRAIN LOCATIONS WOULD SEE GUSTS TO 40KTS NEAR
THE KEWEENAW AND EVEN HIGHER IF MIXING CAN OCCUR FASTER.
ELSEWHERE...WITH THE LLVL JET QUICKLY SHIFTING THROUGH...ONLY EXPECT
A FEW HOURS OF GUSTS TO 20-30KTS. FRONT WILL SLIDE FROM NW TO SE
ACROSS THE CWA MON AFTN INTO EARLY EVENING AND WINDS WILL QUICKLY
DIMINISH AS IT PUSHES THROUGH. AS FOR CLOUDS/PCPN...EXPECT MAINLY
MID CLOUDS TO AFFECT MUCH OF THE CWA THROUGH THE DAY. LLVLS DON/T
BECOME MOIST UNTIL WELL AFTER THE FRONT HAS SHIFTED TO THE S OF
THE AREA AND NRLY FLOW DROPS THE LOWER CLOUDS IN FROM WRN ONTARIO.
THEREFORE...EXPECT PCPN STAYING OVER NE LK SUPERIOR UNDER THE DEEPER
MOISTURE AND BETTER H850-700 Q-VECTOR CONV. THIS AREA WILL
ALSO HAVE ADDITIONAL MOISTURE FROM LEFT OVER LK ENHANCED PCPN
THAT WILL MOVE NE WITH THE SW WINDS. IT/S THOSE SHOWERS THAT COULD
SLIDE S AS THE WINDS SHIFT AND AFFECT FAR ERN UPPER MI LATE IN THE
AFTN AND EARLY EVENING. FINALLY...MONDAY WILL BE THE FIRST 60
DEGREE DAY IN A WEEK FOR MUCH OF UPPER MI...WITH WARM H850 TEMPS
EASILY PUSHING TEMPS INTO THE 60S.
LK ENHANCED CLOUDS INCREASING MON NIGHT AND COULD SEE SOME LIGHT
SHOWERS OVER THE NCNTRL HIGHER TERRAIN AS H850 TEMPS FALL ENOUGH TO
PUT DELTA-T VALUES TO 14. SHALLOW MOISTURE SHOULD LIMIT IT TO VERY
ISOLATED SHOWERS OVER THE NCNTRL CWA AND EXPECT THIS TO CONTINUE
INTO TUES. HIGH PRESSURE RIDGE WILL ALSO BEGIN TO SLIDE OVER THE
UPPER GREAT LAKES FROM THE CANADIAN PRAIRIES ON TUES AND LEAD TO A
DIMINISHING TREND TO POPS. HIGHS ON TUES SHOULD BE IN THE 50S AND
LOWER 60S...WITH THE WARMEST TEMPS AWAY FROM LK SUPERIOR WHERE THERE
WILL BE MORE SUN.
SECONDARY SHORTWAVE PROGGED TO DROP THROUGH THE UPPER GREAT LKS
ON TUES NIGHT. LLVL MOISTURE ASSOCIATED WITH THE FEATURE AND
H850 TEMPS FALLING TO AROUND -1C SHOULD LEAD TO LK ENHANCED
CLOUDS/SHOWERS REDEVELOPING UNDER NNW FLOW. WITH DECENT LLVL
MOISTURE FROM THE WAVE...EXPECT LK ENHANCED CLOUDS/SHOWERS TO
DEVELOP UNDER THE NNW FLOW THROUGH THE NIGHT. MAY BE A LITTLE
DEEPER MOISTURE OVER ERN LK SUPERIOR AND WITH THE SLIGHTLY COOLER
TEMPS...HAVE POPS INTO THE CHANCE CAT OVER SCNTRL/ERN PORTIONS OF
LK SUPERIOR AND SLIGHT CHANCES ONSHORE. EXPECT THESE SHOWERS TO
CONTINUE INTO THE FIRST HALF OF WED.
SFC HIGH AND UPPER RIDGING WILL THEN BUILD OVER THE CWA WED AFTN
INTO THURS AND PRODUCE DRY CONDITIONS. LLVL MOISTURE SHOULD EXIT AND
LEAD TO CLEARING SKIES WED NIGHT. THUS...EXPECT A COLD NIGHT WITH
THE AREA UNDER THE SFC HIGH AND PWATS AROUND 50 PERCENT OF NORMAL.
WILL FOLLOW PREVIOUS SHIFTS ON GOING BELOW GUIDANCE AND INTERIOR
TEMPS AROUND 30 DEGREES. THIS SHOULD PRODUCE ANOTHER FROST/FREEZE
OVER MUCH OF THE CWA.
UNCERTAINTY STARTS TO ARRIVE IN THE MODELS FOR FRI...AS
GFS/GEM/ECMWF ARE ALL SHOWING A SHORTWAVE APPROACHING THE UPPER
GREAT LAKES BUT DIFFER GREATLY IN TIMING AND LOCATION. THIS IS TO
BE EXPECTED AS THERE ARE INDICATIONS THAT IT BECOMES CUTOFF FROM
THE NRN STREAM FLOW DUE TO A STRONGER WAVE EXITING THE PAC NW. WITH
THIS UNCERTAINTY...AND DRY HIGH PRESSURE RIDGE LIKELY REMAINING
OVER THE CWA...WILL GO WITH A DRY FORECAST FOR FRI/SAT. STANDARDIZED
ANOMALIES OF H500 HEIGHTS ARE AROUND 0.5 TOWARDS FOR THE END OF THE
WEEK...WHICH SHOULD LEAD TO NORMAL TO ABOVE NORMAL TEMPERATURES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 134 PM EDT SUN SEP 23 2012
NW FLOW LAKE EFFECT CLOUDS AND SCATTERED SHOWERS WILL CONTINUE
TODAY...AND WILL BE CONTINUING TO WIND DOWN FROM W TO E AS
INCREASINGLY DRIER AIR ADVECTS INTO THE AREA. -SHRA HAVE ALREADY
ENDED AT KIWD...AND VFR CONDITIONS WILL BE THE RULE THRU THE FCST
PERIOD. AT KCMX THERE IS POTENTIAL FOR BRIEF PERIODS OF MVFR CIGS
THIS AFTERNOON AND EVENING...BUT VFR CONDITIONS WILL LIKELY PREVAIL.
AT KSAW...A FEW LAKE EFFECT RAIN SHOWERS ARE EXPECTED FOR THE FIRST
2 HOURS OR SO OF THE TAF PERIOD UNTIL WINDS TURN MORE NW...WHICH IS
NOT FAVORABLE FOR LAKE EFFECT...SO VFR CONDITIONS SHOULD BE THE
RULE. TIGHTENING PRES GRADIENT TONIGHT WILL LEAD TO POSSIBLE LLWS
TONIGHT...THEN GUSTY WINDS MONDAY...ESPECIALLY AT CMX.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 534 AM EDT SUN SEP 23 2012
SINCE HIGH PRES CURRENTLY OVER THE CNTRL STATES MOVES TO THE OHIO
VALLEY RATHER THAN ACROSS THE GREAT LAKES...WINDS WON`T DIMINISH
MUCH TODAY. SPEEDS WILL LIKELY REMAIN MOSTLY IN THE 15-25KT RANGE AS
NW WINDS BACK MORE WESTERLY. TONIGHT AND MON...TIGHTENING PRES
GRADIENT BTWN THE HIGH TO THE S AND AN APPROACHING COLD FRONT FROM
THE N WILL RESULT IN WINDS RAMPING UP TONIGHT THRU MON MORNING. WSW
GALES OF 35-40KT APPEAR LIKELY OVER MUCH OF THE LAKE. STRONGEST
WINDS WILL OCCUR BTWN ISLE ROYALE AND THE KEWEENAW AND IN PARTICULAR
AROUND THE W SIDE OF THE KEWEENAW DUE TO COASTAL CONVERGENCE. SOME
GUSTS MAY REACH 45KT. AS FRONT PASSES...WINDS WILL QUICKLY DIMINISH
LATE MON AFTN/EVENING. WINDS TUE THRU THU SHOULD BE UNDER 20KT AS
SFC HIGH PRES BUILDS OVER THE GREAT LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 8 AM TO 5 PM EDT MONDAY FOR LSZ245-265-267.
GALE WARNING FROM 2 AM TO 5 PM EDT MONDAY FOR LSZ263-264-266.
GALE WARNING FROM 5 AM TO 5 PM EDT MONDAY FOR LSZ243-244.
LAKE MICHIGAN...
GALE WATCH FROM MONDAY MORNING THROUGH MONDAY AFTERNOON FOR
LMZ221-248-250.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...TITUS
MARINE...ROLFSON
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
825 PM CDT MON SEP 24 2012
.UPDATE...
ISSUED AT 822 PM CDT MON SEP 24 2012
LATEST RUC AND HRRR CONTINUE TO SUPPORT CATEGORICAL POPS ALONG AND
NORTH OF INTERSTATE 70 BETWEEN 06Z AND 12Z. CONVECTIVE INITIATION
SHOULD OCCUR ACROSS NORTHWEST MISSOURI BETWEEN 04Z AND 06Z AND
QUICKLY GROW UPSCALE INTO A CONVECTIVE COMPLEX THAT WILL MOVE EAST
ACROSS THE NORTHERN HALF OF MISSOURI INTO CENTRAL/SOUTHWEST
ILLINOIS. NO MAJOR CHANGES MADE TO THE FORECAST.
CVKING
&&
.SHORT TERM...
ISSUED AT 251 PM CDT MON SEP 24 2012
(TONIGHT)
WHAT LOOKS TO BE A RATHER ACTIVE/WET WORK WEEK SHOULD BEGIN TONIGHT.
STRONG WARM/MOIST ADVECTION WILL COMMENCE OVER THE AREA AFTER DUSK
AS A 45-50 KT SOUTHWESTERLY LLJ DEVELOPS. UPPER LEVEL FORCING
MECHANISMS IN THE FORM OF DCPVA DOWNSTREAM OF A 500-HPA TROUGH AND
RIGHT ENTRANCE REGION OF A 60-KT UPPER LEVEL JET WILL HELP PROVIDE
UVM ON THE SYNOPTIC SCALE. THE COLLOCATION OF THESE AFOREMENTIONED
FORCING MECHANISMS LOOKS TO TAKE PLACE ALONG AND JUST NORTH OF THE
INTERSTATE 70 CORRIDOR IN MISSOURI AND I-64 CORRIDOR IN ILLINOIS.
HAVE PLACED CATEGORICAL POPS LATE TONIGHT IN THIS REGION TO ACCOUNT
FOR THIS. AFTER INVESTIGATING NWP SOUNDINGS...CONVECTION SHOULD BE
ROOTED ABOVE A STABLE NOCTURNAL INVERSION WITH SOME OF THE STRONGER
STORMS CAPABLE OF PRODUCING LARGE HAIL GIVEN STEEP MIDLEVEL LAPSE
RATES AND AMPLE ELEVATED CAPE WITHIN HAIL GROWTH ZONE.
FOLLOWED 0900 UTC SREF/1200 UTC NAM FAIRLY CLOSELY FOR POPS/QPF. FOR
LOW TEMPERATURES...DID NOT DEVIATE SUBSTANTIALLY FROM MOS OUTPUT.
DID GO A BIT ABOVE GUIDANCE IN FAR NORTHERN/SOUTHERN CWA WHERE
LOWEST POPS/QPF ARE LOCATED. ALSO TRIED MY BEST TO CAPTURE A W/E
ORIENTED AXIS OF COOLER LOW TEMPERATURES COLLOCATED WITH AXIS OF
HEAVIEST RAINFALL AND HIGHEST POPS TO ACCOUNT FOR POTENTIAL
EVAPORATIVE COOLING.
GOSSELIN
&&
.LONG TERM...
ISSUED AT 251 PM CDT MON SEP 24 2012
(TOMORROW THROUGH SUNDAY)
THE PRIMARY FCST ISSUE OVER THE NEXT FEW DAYS IS PCPN CHCS. THIS IS
A COMPLICATED FCST BECAUSE PCPN CHCS FOR EACH DAY WILL DEPEND TO
SOME EXTENT ON WHAT WILL HAVE HAPPENED THE PREVIOUS NIGHT...AND
THOSE KINDS OF MESOSCALE DETAILS ARE DIFFICULT TO PIN DOWN
ACCURATELY MORE THAN A FEW HOURS IN ADVANCE. THE BEST WAY TO
INTERPRET THE WIDESPREAD CHC POPS IN THIS FCST PCKG IS THAT PCPN IS
POSSIBLE ALMOST ANYWHERE EVEN THOUGH IT PROBABLY WILL NOT RAIN
EVERYWHERE.
ELEVATED CONVECTION IS EXPECTED TO BE ONGOING ACROSS PARTS OF THE
CWA AT 12Z TUE DUE TO A STRONG LLJ IMPINGING ON A N-S ORIENTED WMFNT
LOCATED WEST OF THE CWA AND AIDED BY LARGE SCALE ASCENT AHEAD OF
A WEAK SHORTWAVE. TSRA COVERAGE SHOULD DIMINISH THROUGH THE
MORNING ONCE THE LLJ BEGINS TO WEAKEN. A SFC LOW PRESSURE CENTER
RIDING ALONG THE QUASISTATIONARY FNT IN KS WILL MOVE INTO CENTRAL
MO AND PUSH THE WMFNT THROUGH THE CWA BY LATE TUE AFTN...KEEPING
THE QUASISTATIONARY BDRY IN PLACE ACROSS SRN IA OR NRN MO.
ALTHOUGH THIS WILL PLACE THE CWA IN THE WARM SECTOR FOR THE
AFTN...RESIDUAL CLOUDINESS FM OVERNIGHT CONVECTION SHOULD LIMIT
WIDESPREAD DESTABILIZATION ALTHOUGH ISO-SCT TSRA COULD STILL
DEVELOP ON TUE AFTN IF THERE ARE POCKETS OF CLRG...ESPECIALLY
GIVEN MODEL FCSTS OF FAVORABLE H7-H5 LAPSE RATES SPREADING ACROSS
THE AREA.
THE KEY ISSUE MODULATING PCPN CHCS BEYOND TUE AFTN WILL BE THE
LOCATION OF THE QUASISTATIONARY BDRY MENTIONED ABOVE. THERE WILL NOT
BE MUCH IN THE WAY OF UPPER LEVEL SUPPORT TO INFLUENCE ITS POSITION
THIS WEEK. A HIGH PRESSURE CENTER WILL BE SLIDING SEWD FM CANADA
INTO THE GRTLKS FM TUE THROUGH THU AND THE CIRCULATION AROUND THAT
SFC HIGH COMBINED WITH THE CIRCULATIONS AROUND PERIODIC SFC LOWS
WILL ACT TO SHARPEN THE TEMPERATURE CONTRAST ACROSS THE
QUASISTATIONARY BDRY AND LIMIT ITS NWD PROGRESS. AT THE SAME
TIME...CONVECTIVE INFLUENCES MAY END UP PUSHING THE EFFECTIVE FRONT
EVEN FARTHER SOUTH THAN INDICATED BY THE MODELS. FINALLY...THE
STRENGTH OF THE HIGH PRESSURE CENTER WILL ALSO INFLUENCE THE INITIAL
LOCATION OF THE BDRY.
ATTM MODELS ARE IN GOOD AGREEMENT THAT THE BDRY WILL BE LOCATED
RIGHT ALONG THE MO/IA BORDER FOR MOST OF TUE NIGHT. A BROAD SWLY LLJ
THEN DVLPS OVERNIGHT ALONG WITH PW VALUES OF 1.3 TO 1.5 INCHES WHICH
IS AROUND THE 75TH PERCENTILE FOR SEPT IN THIS PART OF THE COUNTRY.
CONCEPTUAL MODELS SUPPORT THE IDEA THAT A QUASISTATIONARY E-W BDRY
WITH A NOCTURNAL LLJ NEARLY PARALLEL TO IT AND ON ITS WARM SIDE
WOULD LEAD TO AN ELONGATED AREA OF PCPN VERY CLOSE TO THE BDRY.
GFS/NAM ALSO SUPPORT THIS IDEA WITH CORFIDI VECTORS POINTED
UPSTREAM...SUGGESTING THAT NEW CONVECTION WILL CONTINUOUSLY DVLP AND
MOVE ENEWD WITHIN THE OVERALL BAND OF PCPN. PCPN SHOULD CONTINUE
THROUGH AT LEAST PART OF WED MORNING UNTIL THE LLJ WEAKENS.
MODELS BEGIN TO DIFFER ON THE LOCATION OF THE BDRY BY WED/THU AND IT
IS ENTIRELY POSSIBLE THAT THE EFFECTIVE BDRY MAY HAVE BEEN PUSHED
FARTHER SOUTH THAN THE MODELS SUGGEST DUE TO OUTFLOW BDRYS FROM
OVERNIGHT CONVECTION ON THE PREVIOUS COUPLE OF NIGHTS. THERE IS
LITTLE EVIDENCE OF A LLJ ON WED NIGHT OR THU NIGHT HOWEVER THE BDRY
WILL STILL BE PRESENT AND FAVORABLY POSITIONED BENEATH THE LEFT EXIT
REGION OF A H25 JET ON THU NIGHT AND FRI NIGHT. ULTIMATELY...SCT
PCPN IS USUALLY A FAIR BET WITH A QUASISTATIONARY BDRY ACROSS THE
AREA AND EVEN A HINT OF FORCING...THEREFORE WILL CONTINUE WITH
SCHC-CHC POPS THROUGH AT LEAST FRI. BEYOND FRI...MODELS SHOW THAT
THE QUASISTATIONARY FNT WILL BE PUSHED SWD AS A CDFNT BEFORE
STALLING SOMEWHERE IN THE REGION BY THE WEEKEND...BRINGING COOLER
TEMPERATURES TO PARTS OF MO/IL LATE IN THE FCST PD.
KANOFSKY
&&
.AVIATION...
ISSUED AT 609 PM CDT MON SEP 24 2012
WINDS SHUD DIMINISH SLIGHTLY THIS EVE AND BACK AHEAD OF AN
APPROACHING WRMFNT AND SFC LOW. AS THE LLJ INCREASES
TONIGHT...EXPECT TSRA TO DEVELOP AHEAD OF THE SFC LOW ACROSS WRN
AND CENTRAL MO AND SPREAD EWD. TSRA SHUD TRAVEL ALONG AND JUST N
OF I70. BELIEVE PREV TAFS HAVE A GOOD HANDLE ON THIS TREND AND FEW
CHANGES WERE MADE. TSRA SHUD MOVE OUT OF REGION/DIMINISH TUES
MORNING. IS STILL SOME QUESTION ABOUT TSRA DURING THE REMAINDER OF
THE DAY...BUT BELIEVE TERMINALS WILL BE DRY INTO THE EVENING
HOURS. EXPECT TSRA TO INITIATE AGAIN TUES EVENING...LIKELY CLOSE
TO MIDNIGHT WITH A SIMILAR TRACK TO TONIGHT AS THE SFC FNT WILL
REMAIN STATIONARY.
OTHERWISE...WINDS WILL BECOME SWLY S OF THE SFC FNT WITH GUSTS TO
20 KTS AT ALL TERMINALS EXCEPT FOR UIN. GUSTS MAY BE HIGHER
ESPECIALLY IN THE MORNING AS MIXING BEGINS. THESE GUSTS WILL
DIMINISH TUES EVENING WITH SUNSET.
SPECIFICS FOR KSTL...FEW CHANGES TO THE PREV TAF. STILL EXPECT
TSRA TO IMPACT TERMINAL LATE TONIGHT THRU DAWN TUES. EXPECT TSRA
TO DIMINISH/MOVE E OF TERMINAL SHORTLY AFTER SUNRISE. REGION SHUD
REMAIN DRY THRU MUCH OF THE DAY WITH THE NEXT ROUND OF TSRA
INITIATING TUES NIGHT ACROSS WRN/CENTRAL MO AND MOVING EWD.
BELIEVE BEST CHANCES FOR TSRA TUES NIGHT WILL BE NEAR THE END OF
THE TAF PERIOD AND WILL ALLOW FUTURE UPDATES TO PROVIDE BETTING
TIMING. OTHERWISE...WINDS WILL BECOME SWLY S OF THE SFC FNT TUES
MORNING WITH GUSTS TO AROUND 20 KTS. WINDS WILL DIMINISH WITH
SUNSET.
TILLY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
900 PM EDT MON SEP 24 2012
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL BEGIN TO APPROACH THE AREA TONIGHT.
A FRONTAL BOUNDARY WILL SETTLE INTO THE AREA KEEPING PRECIPITATION
CHANCES IN THE FORECAST FOR MUCH OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
SKIES ARE CLEAR ACROSS THE AREA THIS EVENING...BUT EXPECT TO SEE
AN INCREASE IN CLOUDS LATER TONIGHT AS A MID LEVEL SHORT WAVE
APPROACHES FROM THE WEST. AHEAD OF THIS...THE LOW LEVEL FLOW WILL
BACK SLIGHTLY AND WE WILL SEE SOME DEVELOPING ISENTROPIC LIFT
TOWARD DAYBREAK. THIS COULD LEAD TO A FEW SHOWERS LATE. THE 18Z NAM
AND LATEST RAP ARE BOTH SHOWING SOME WEAK ELEVATED INSTABILITIES
WORKING IN LATE TONIGHT TOO SO WILL HANG ON TO THUNDER WORDING
ALTHOUGH THINK THE CHANCE WILL BE PRETTY LOW.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
A FRONTAL BOUNDARY WILL APPROACH AND THEN MEANDER AROUND THE FA
THROUGH THE SHORT TERM TIME FRAME. THIS WILL ALLOW FOR OFF AND ON
PRECIPITATION THROUGH THIS TIME. THERE IS STILL SOME UNCERTAINTY
IN WHERE THE EXACT LOCATION OF THE BOUNDARY WILL BE HOWEVER CURRENT
INDICATIONS ARE THAT SOME LOCATIONS ACROSS CENTRAL PORTIONS OF THE
FA WILL HAVE THE POTENTIAL FOR AN INCH OR TWO OF RAIN THROUGH THE
SHORT TERM TIME FRAME. THE FRONTAL BOUNDARY WILL BEGIN TO MOVE
SOUTH BY THE END OF THE SHORT TERM ENDING PRECIPITATION CHANCES
ACROSS NORTHERN PORTIONS OF THE FA. WITH DECENT INSTABILITY ACROSS
THE AREA ON WEDNESDAY A FEW OF THE STORMS MAY BE STRONG TO SEVERE
WITH DAMAGING WINDS AND HAIL THE PRIMARY THREATS. HIGH TEMPERATURES
WILL GENERALLY BE IN THE 70S WITH LOWS IN THE 50S AND 60S.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
THERE IS UNCERTAINTY WHERE A NEARLY STATIONARY FRONT WILL SET UP.
BUT AT THIS POINT IT APPEARS THAT IT WILL BE CLOSE ENOUGH TO THE
SOUTHERN ZONES TO KEEP A CHANCE OF SHOWERS AND POSSIBLY SOME THUNDER
THURSDAY INTO FRIDAY. EXPECT THE BOUNDARY TO FINALLY GET PUSHED
FURTHER SOUTH AS HIGH PRESSURE BUILDS IN ON THE BACK SIDE OF A
DEVELOPING UPPER LOW. THIS SHOULD SPREAD DRIER AIR ACROSS THE REGION
FOR THE WEEKEND INTO MONDAY. TEMPERATURES WILL BE NEAR NORMAL
THROUGH THE PERIOD.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
A MID LEVEL SHORT WAVE WILL MOVE OUT OF THE MID MISSISSIPPI VALLEY
TONIGHT AND ACROSS OUR AREA THROUGH THE DAY ON TUESDAY. AHEAD OF
THIS...MOSTLY CLEAR SKIES THIS EVENING WILL GIVE WAY TO INCREASING
HIGH AND THEN MID LEVEL CLOUDS LATER TONIGHT. THIS COULD LEAD TO A
FEW SPRINKLES OR LIGHT RAIN SHOWERS LATE TONIGHT INTO TUESDAY
MORNING...BUT THINK THEY WILL REMAIN OPERATIONALLY INSIGNIFICANT.
AS BETTER FORCING MOVES IN THROUGH THE DAY AND WE BEGIN TO
DESTABILIZE A BIT MORE...SCATTERED SHOWERS AND THUNDERSTORMS WILL
BECOME MORE WIDESPREAD THROUGH THE AFTERNOON HOURS. THERE IS SOME
UNCERTAINTY AMONG THE MODELS AS TO WHERE EXACTLY THE BEST CHANCE
FOR PCPN WILL LINE UP. RIGHT NOW...IT APPEARS THAT NORTHERN
PORTIONS OF OUR FA MAY HAVE THE BETTER CHANCE SO WILL HIT THE PCPN
A LITTLE HARDER THERE.
.OUTLOOK...THUNDERSTORMS AND MVFR CONDITIONS POSSIBLE THROUGH
WEDNESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...NOVAK
NEAR TERM...JGL
SHORT TERM...NOVAK
LONG TERM...
AVIATION...JGL
AREA FORECAST DISCUSSION
NWS TULSA OK
942 PM CDT MON SEP 24 2012
...UPDATE...
.DISCUSSION...
LATEST RUC ANALYSIS SUGGEST THE ELEVATED FRONTAL ZONE WILL REMAIN
WELL TO OUR NORTH AND JUST EAST OF THE FORECAST AREA OVERNIGHT.
THUS WILL REMOVE OVERNIGHT THUNDERSTORM MENTION. WILL ALSO
INCREASE OVERNIGHT CLOUD COVER GIVEN DENSE CIRRUS CANOPY AND MAKE
MINOR ADJUSTMENT TO WIND SPEEDS. THE FIRE WEATHER WATCH WILL
REMAIN IN EFFECT FOR TUESDAY...WITH PORTIONS OF THE WATCH POSSIBLY
UPGRADED TO A RED FLAG WARNING PENDING NEW DATA TRENDS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 72 91 68 88 / 10 20 30 20
FSM 64 94 66 90 / 10 10 10 10
MLC 70 92 70 90 / 10 0 10 10
BVO 65 91 63 87 / 10 20 40 30
FYV 63 88 63 86 / 10 10 10 20
BYV 65 87 66 84 / 10 20 20 30
MKO 66 92 68 85 / 10 10 20 10
MIO 67 89 65 79 / 10 20 40 40
F10 69 92 70 86 / 10 10 20 10
HHW 68 91 67 90 / 10 0 10 0
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...FIRE WEATHER WATCH FROM NOON TUESDAY TO 9 PM TUESDAY FOR OKZ049-
OKZ053-OKZ054-OKZ055-OKZ059-OKZ060-OKZ061-OKZ064-OKZ065-
OKZ066-OKZ067-OKZ070-OKZ071-OKZ073-OKZ074-OKZ075-OKZ076.
AR...NONE.
&&
$$
SHORT TERM...07
AREA FORECAST DISCUSSION...UPDATED
NWS MELBOURNE FL
345 AM EDT TUE SEP 25 2012
.DISCUSSION...
TODAY-TONIGHT...
A LARGE HI PRES RIDGE SPANNING THE ERN SEABOARD AND THE DEEP SOUTH
WILL PUSH INTO THE W ATLC TODAY...GENERATING A DEEP AND STEADY E/NE
FLOW ACRS CENTRAL FL. LATEST RAP ANALYSIS SHOWS A TONGUE OF DRY AIR
LINGERING OVER THE CENTRAL PENINSULA S OF THE I-4 CORRIDOR...BUT
WITH DEEPER MOISTURE PUSHING DOWN THE ERN PANHANDLE PENINSULA. RADAR
OBS CONFIRM THIS WITH THIN BUT PERSISTENT SHRA BANDS OFF THE VOLUSIA
CO COAST. DEEPER MOISTURE ALSO NOTED OVER MUCH OF THE BAHAMA BANK.
H85-H50 LAPSE RATES BTWN 5.5-6.0C/KM INDICATE SOME DEGREE OF
INSTABILITY...BUT WITH H85-H70 RATES BLO 5.0C/KM..IT WILL BE
DIFFICULT TO INITIALIZE DEEP VERTICAL MOTION.
AS THE RIDGE EXPANDS EWD...LOW/MID LVL WINDS WILL SHIFT MORE TO THE
E...SHUNTING MOISTURE INTO WHAT REMAINS OF THE DRY AIR SLOT.
ALOFT...A MID/UPR LVL RIDGE AXIS OVER THE FL STRAITS WILL PUSH A
BAND OF MID LVL VORTICITY BAND OUT OF S FL AND ACRS LAKE OKEECHOBEE.
A DEPARTING H30-H20 JET STREAK OFF THE CAROLINA COAST WILL CONTINUE
TO DRAG CONSIDERABLE HIGH CLOUDS ACRS THE PENINSULA AS WELL.
DESPITE THE INCREASING MID LVL VORTICITY...OVERALL INSTABILITY WILL
BE LIMITED. THE COMBINED EFFECTS OF THE LINGERING DRY AIR...DENSE
UPR CLOUD DECK LIMITING INSOLATION...AND VERY WEAK H85-H70 LAPSE
RATES WILL BE TOO MUCH TO GENERATE TSRAS. THROW IN THE DEEPENING
ONSHORE FLOW THAT WILL CREATE A DIFFUSE EAST COAST SEA BREEZE WITH
WEAK SFC/LOW LVL FORCING...AND THUNDER CHANCES BECOME TOO LOW TO
MENTION. WILL GO WITH ISOLD COASTAL SHRAS THRU EARLY AFTN...
AREAWIDE THRU EARLY EVNG...THEN BACK TO COASTAL THRU TONIGHT.
ONSHORE FLOW AND CONSIDERABLE UPR LVL CLOUDS WILL KEEP MAX TEMPS
NEAR AVG (M80S)...MIN TEMPS ABV AVG (L70S).
WED-THU...
SURFACE HIGH PRESSURE RIDGE NORTH OF THE AREA WILL PROVIDE AN
EASTERLY WIND FLOW. THE LATEST GFS RUN SHOWS OLD FRONTAL BAND
MOISTURE LIFTING BACK INTO THE AREA WED SO HAVE MAINTAINED CHANCE
POPS (30 PERCENT COAST AND 40 PERCENT INLAND). THE GFS SHOWS AN
UPPER LEVEL SHORTWAVE TROUGH APPROACHING THU SO HAVE GONE WITH 40
POPS AREAWIDE.
FRI-TUE...
UPPER LEVEL SHORTWAVE TROUGH SHOULD SHIFT EAST OF THE AREA ON FRI
AND DECREASE POPS. THE GFS INDICATES LOWER POPS SO HAVE GONE WITH
30 PERCENT AREAWIDE.
WEEKEND-EARLY NEXT WEEK..THE MODELS GENERALLY AGREE ON A MORE
SUBSTANTIAL TROUGH ORGANIZING OVER THE EASTERN PART OF THE
COUNTRY. THERE ARE SOME TIMING AND STRENGTH DIFFERENCES BETWEEN
THE GFS AND ECMWF. THE GFS IS STRONGER...THOUGH THE 00Z ECMWF HAS
TRENDED DEEPER FROM ITS 12Z RUN.
WILL STAY WITH 30-40 POPS THROUGH THE PERIOD...HOWEVER THE SUN-TUE
PERIOD MAY HAVE GREATER CHANCES. WILL WAIT A LITTLE LONGER TO GO
HIGHER THOUGH AS WE DO NOT WANT TO DIFFER TOO MUCH FROM CLIMO THAT
FAR OUT IN THE FORECAST.
&&
.AVIATION...
ALL SITES VFR WITH PREVAILING CIGS AOA FL120 UNLESS OTHERWISE NOTED:
THRU 25/12Z...BRIEF MVFR VSBYS/CIGS IN ISOLD SHRAS N OF KTIX. BTWN
25/12Z-25/24Z...SLGT CHC MVFR SHRAS COASTAL SITES...AFT 25/18Z SLGT
CHC IFR TSRAS INTERIOR SITES...OCNL SFC WND G20KTS COASTAL SITES.
AFT 26/00Z...SLGT CHC MVFR SHRAS COASTAL SITES.
&&
.MARINE...
TODAY-TONIGHT...
HI PRES RIDGE AXIS EXTENDING FROM THE CANADIAN MARITIMES...ACRS THE
NC OUTER BANKS...O THE RIO GRANDE VALLEY WILL GENERATE A GENTLE TO
MODERATE E/NE BREEZE ACRS THE LCL ATLC. EARLY AM OBS FROM THE DATA
BUOYS SHOW THE SWELL THAT HAS BEEN ANTICIPATED FOR THE PAST FEW DAYS
HAS BEGUN IMPACTING THE WATERS WELL OFFSHORE. BOUY010/012 BOTH HAVE
MEASURED +6FT SEAS SINCE MIDNIGHT WITH A 4-5FT SWELL COMPONENT.
BUOY009 STILL HOLDING BTWN 3-4FT...BUT THIS WILL CHANGE NOTICEABLY
BY DAYBREAK AS SWELL TRAIN ADVANCES WESTWARD.
INITIALLY SEAS MAY BUILD UP TO 7FT IN THE GULF STREAM BUT WILL FALL
BACK TO ARND 6FT BY AFTN AS THE LEADING EDGE OF THE SWELL DAMPENS
OUT ON THE E FL COAST. THIS WINDOW IS TOO NARROW TO WARRANT AN SCA
WITH THE MORNING PACKAGE. HOWEVER... A CAUTIONARY STATEMENT FOR THE
OFFSHORE LEG N OF SEBASTIAN INLET IS PRUDENT AS A SLIGHTLY TIGHTER
PGRAD WILL SUPPORT SFC/BNDRY LYR WNDS ARND 15KTS WITH OCNL GUSTS
OVER 20KTS.
WED-THU...
HIGH PRESSURE RIDGE NORTH OF THE WATERS WILL MAINTAIN AN EASTERLY
WIND FLOW. THE LATEST MARINE MOS INDICATES SPEEDS ABOUT 10-13 KNOTS.
HIGHER MOISTURE IS FORECAST TO RETURN SO THE CHANCE FOR
SHOWERS/STORMS WILL BE INCREASING.
FRI-SAT...
THE HIGH PRESSURE RIDGE IS FORECAST TO WEAKEN. THE LATEST GFS
INDICATES WINDS 5-10 KNOTS MOSTLY FROM THE EAST. RAIN CHANCES MIGHT
SLIGHTLY DECREASE FROM THE WED-THU VALUES.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 85 71 87 75 / 20 20 30 20
MCO 86 72 90 73 / 20 10 40 20
MLB 87 73 87 77 / 20 20 30 20
VRB 86 73 88 75 / 20 20 30 20
LEE 87 70 90 73 / 20 10 40 20
SFB 86 72 89 74 / 20 10 40 20
ORL 86 72 90 75 / 20 10 40 20
FPR 86 73 87 75 / 20 20 30 20
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...BRAGAW
LONG TERM/IMPACT WX...LASCODY
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
320 AM EDT TUE SEP 25 2012
.SYNOPSIS...
07Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A SOMEWHAT FLATTER UPPER
LEVEL PATTERN COMPARED TO 24 HOURS AGO AS THE LONGWAVE TROUGH OVER
THE EASTERN CONUS DE-AMPLIFIES. THE MID-LEVEL FLOW LEFT BEHIND
ACROSS THE SOUTHEASTERN STATES HAS TAKEN ON A MORE ZONAL PATTERN.
ONE OTHER FEATURE OF NOTE IS A UPPER LOW SPINNING NEAR THE 4-CORNERS
REGION THIS MORNING. THIS ENERGY IS FORECAST TO SLOWLY SHEAR OUT AS
IT PUSHES EASTWARD THE NEXT FEW DAYS WITH LITTLE TO NO IMPACT ON OUR
LOCAL WEATHER. IN THE UPPER LEVELS...SOUTHERN STREAM FLOW CONTINUES
TO BRING AMPLE MOISTURE NORTHWARD OVER THE EASTERN GULF AND FL
PENINSULA. THIS JET ENERGY WILL KEEP THE HIGH LEVEL CIRRUS A PART OF
THE FORECAST THROUGH THE DAY...ESPECIALLY OVER CENTRAL AND SOUTHERN
PORTIONS OF THE PENINSULA. 00Z KTBW SOUNDING SHOWS THIS MOISTURE
ABOVE 400MB...OVERTOP A STILL VERY DRY COLUMN THROUGH THE MIDDLE AND
LOWER PORTIONS OF THE TROPOSPHERE. THIS MAJORITY DRY COLUMN IS
RESULTING IN A PW VALUE ON THAT SOUNDING OF ONLY AROUND 0.8"...WHICH
IS AROUND 1/2 OF CLIMO FOR LATE SEPTEMBER.
AT THE SURFACE...OLD FRONTAL BOUNDARY CONTINUES TO DECAY/WASH OUT
OVER THE SOUTHERN FL PENINSULA THIS MORNING WITH OUR LOCAL GRADIENT
BECOME MORE AND MORE DOMINATED BY THE 1024MB HIGH PRESSURE RIDGE TO
OUR NORTH. A GENERAL NE/E FLOW AT THE SURFACE AROUND THIS RIDGE WILL
BRING A RETURN OF ATLANTIC MOISTURE AND HUMID CONDITIONS TO THE
REGION THROUGH THE MIDDLE OF THE WEEK.
&&
.SHORT TERM (TODAY THROUGH THURSDAY)...
TODAY/TONIGHT...THE STRENGTH OF THE MID-LEVEL DRY AIR SHOULD HOLD
TODAY OVER CENTRAL AND NORTHERN ZONES KEEPING THE FORECAST GENERALLY
DRY. AN ISOLATED LOW TOPPED SPEED CONVERGENCE SHOWER OR 2 DURING THE
AFTERNOON IS POSSIBLE UP TOWARD SUMTER COUNTY IF ANY CAN SURVIVE THE
TREK INLAND FROM THE EAST COAST. THESE WILL BE VERY FEW AND FAR
BETWEEN THOUGH. THE FURTHER SOUTH ONE TRAVELS FROM THE I-4
CORRIDOR...AND THE FASTER THE DRY AIR WILL ERODE AND HENCE BETTER
CHANCES FOR A FEW AFTERNOON SHOWERS. NWP GUIDANCE OFTEN HAS A BIT OF
A FAST BIAS TOWARD THE EROSION OF THESE DRY LAYERS AND WILL ONLY ADD
A SLIGHT CHANCE POP FOR NOW. AS MENTIONED IN THE SYNOPSIS...THE
FORECAST WILL FEATURE OF MIX OF SUN AND CLOUDS...ALTHOUGH THE HIGH
LEVEL CIRRUS MAY WIN OUT AT TIMES OVER THE CENTRAL AND SOUTHERN
ZONES. REGARDLESS...SHOULD STILL SEE ENOUGH INSOLATION TO ALLOW
AFTERNOON TEMPS TO CREEP UP TO WITHIN A DEGREE OR 2 OF 90.
ANY ISOLATED SHOWERS SHOULD DISSIPATE QUICKLY WITH SUNSET SETTING UP
A GENERALLY DRY OVERNIGHT PERIOD FOR LAND ZONES. THE INCREASING LOW
LEVEL MOISTURE WILL SLOW THE TEMPERATURE DROP AND WILL CERTAINLY SEE
LESS LOCATIONS REACHING THE MIDDLE AND UPPER 60S COMPARED TO THIS
MORNING. BEST CHANCES TO DROP BELOW 70 WILL BE UP OVER THE NATURE
COAST ZONES...AND ALSO THE NORMALLY COOLER SPOTS OF DE SOTO...HARDEE
AND HIGHLANDS COUNTIES.
WEDNESDAY/THURSDAY...EASTERLY LOW LEVEL FLOW WILL CONTINUE AROUND
HIGH PRESSURE PARKED OVER THE CAROLINAS. GFS/NAM/ECMWF ALL SHOW THAT
MUCH OF THE MID-LEVEL DRY AIR WILL HAVE BEEN ERODED BY THIS PERIOD
ALLOWING FOR A MUCH LESS HOSTILE COLUMN FOR CONVECTION. WILL BRING
MORE NORMAL SCT SHOWER/STORMS CHANCES BACK TO THE FORECAST (30-40%)
FOR BOTH WEDNESDAY AND THURSDAY AFTERNOONS. OVERNIGHT LOWS WILL
CONTINUE TO MODERATE A FEW DEGREES EACH DAY WITH DAYTIME HIGHS
REMAINING IN THE UPPER 80S TO LOWER 90S.
&&
.LONG TERM (FRIDAY THROUGH NEXT MONDAY)...
A RATHER COMPLEX SYNOPTIC PATTERN WILL BE SETTING UP OVER NORTH
AMERICA DURING THE EXTENDED PORTION OF THE FORECAST...BUT THE
IMPACTS TO OUR AREA WILL LIKELY BE BEYOND DAY SEVEN.
THE 00Z GFS...12Z ECMWF AND 00Z CANADIAN ALL START THE EXTENDED
PERIOD WITH AN UPPER-LEVEL AREA OF HIGH PRESSURE OVER THE WESTERN
GULF WITH A RIDGE EXTENDING EASTWARD ACROSS THE NORTHERN GULF. THE
GFS SHOWS A POTENT SHORT WAVE TROUGH DIGGING SOUTHEASTWARD TOWARD
THE GREAT LAKES ON FRIDAY THEN TURNING EASTWARD AND MOVING ACROSS
SOUTHERN CANADA AND TOWARD THE CANADIAN MARITIMES OVER THE WEEKEND.
THE ECMWF AND CANADIAN BOTH START WITH THE SHORT WAVE ENERGY
DROPPING TOWARD THE GREAT LAKES ON FRIDAY BUT THEN SHOW NO REAL
EASTWARD MOVEMENT THROUGH AT LEAST SUNDAY. THE ECMWF THEN LIFTS THE
TROUGH NORTHEASTWARD NEAR OR NORTH OF NEW ENGLAND SUNDAY NIGHT AND
MONDAY. THE GFS SOLUTION IS MORE PROGRESSIVE BUT ALLOWS A PIECE OF
THE ENERGY TO STAY BEHIND RESULTING IN A CUT-OFF LOW OVER THE MIDDLE
MISSISSIPPI VALLEY SUNDAY AND MONDAY. THE SLOWER ECMWF KEEPS A
BROADER TROUGH IN PLACE OVER THE EASTERN HALF OF THE COUNTRY WHICH
RESULTS IN A MUCH WEAKER CUT-OFF LOW THAT IS ALSO MORE PROGRESSIVE.
AS MENTIONED EARLIER... REGARDLESS OF WHICH SCENARIO UNFOLDS...ANY
SIGNIFICANT IMPACTS OF THIS SYSTEM WILL BE BEYOND THIS FORECAST
PERIOD...WITH A POTENTIAL FRONTAL PASSAGE AROUND THE MIDDLE OF NEXT
WEEK.
IN THE MEAN TIME...WILL BASE THE FORECAST ON THE ECMWF WHICH IS
SUPPORTED BY THE CANADIAN MODEL. WE WILL BE DEALING WITH A
SUMMER-LIKE PATTERN FRIDAY THROUGH MONDAY. WEAK SURFACE RIDGING
NORTH OF THE REGION ON FRIDAY WILL SETTLE SOUTHWARD TOWARD FLORIDA
FOR SATURDAY THROUGH MONDAY. WITH AMPLE MOISTURE IN PLACE...EXPECT
AFTERNOON SHOWERS AND THUNDERSTORMS TO DEVELOP ALONG GULF AND BAY
BREEZE BOUNDARIES EACH DAY.
&&
.AVIATION...
VFR NEXT 24 HOURS. SOME PATCHY FOG IS POSSIBLE MAINLY AROUND PGD AND
LAL TOWARD SUNRISE. A FEW SHOWERS COULD DEVELOP LATE IN THE
AFTERNOON FROM PGD SOUTH TO RSW AND FMY...BUT OVERALL COVERAGE WILL
BE TOO LOW FOR MENTION IN TAFS AT THIS TIME.
&&
.MARINE...
NORTHEAST TO EAST FLOW AROUND HIGH PRESSURE CENTERED NEAR THE
CAROLINAS WILL CONTINUE THROUGH THE NEXT SEVERAL DAYS. THE HIGH
POSITION TO OUR NORTH AND NORTHEAST IS FAVORABLE TO SUPPORT
OVERNIGHT SURGES WITHIN THE EASTERLY FLOW. WINDS APPROACHING
CAUTIONARY LEVELS ARE POSSIBLE BOTH TONIGHT AND WEDNESDAY
NIGHT...ESPECIALLY ALONG AND OFFSHORE OF THE NATURE COAST. THE
RIDGE OVER THE CAROLINAS WILL WEAKEN DURING THE LATER PORTION OF
THE WEEK ALLOWING WINDS TO BECOME MORE LIGHT AND VARIABLE BY THE
WEEKEND.
&&
.FIRE WEATHER...
INCREASING LOW LEVEL ATLANTIC MOISTURE ARRIVING ON NORTHEAST TO
EAST FLOW WILL HELP KEEP RELATIVE HUMIDITY VALUES ABOVE CRITICAL
LEVELS THROUGH THE MIDDLE OF THE WEEK. THIS INCREASE IN MOISTURE
ALONG WITH BETTER CHANCES FOR SHOWERS AND STORMS WEDNESDAY AND
THURSDAY WILL FURTHER PREVENT CRITICAL FIRE WEATHER CONDITIONS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 89 73 89 74 / 10 10 40 20
FMY 89 73 90 73 / 20 20 40 20
GIF 90 71 90 72 / 10 10 40 20
SRQ 88 72 88 73 / 10 10 40 20
BKV 90 68 90 69 / 10 10 40 20
SPG 88 76 88 77 / 10 10 40 20
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
414 AM EDT TUE SEP 25 2012
.UPDATE...
AVIATION SECTION UPDATED
&&
.SYNOPSIS...
ISSUED AT 303 AM EDT TUE SEP 25 2012
A COUPLE OF FRONTS WILL MOVE INTO THE AREA AND LINGER THROUGH THE
END OF THE WORK WEEK...KEEPING CHANCES FOR RAIN ACROSS MUCH OF THE
AREA THROUGH THEN. HIGH PRESSURE WILL THEN BUILD IN AND KEEP MUCH OF
THE WEEKEND INTO EARLY NEXT WEEK DRY. TEMPERATURES WILL RETURN TO
BELOW AVERAGE BY THE WEEKEND.
&&
.NEAR TERM /TODAY/...
ISSUED AT 303 AM EDT TUE SEP 25 2012
ISENTROPIC LIFT WILL INCREASE ACROSS THE FORECAST AREA TODAY AS A
COUPLE OF FRONTAL SYSTEMS APPROACH THE AREA...ALONG WITH AN UPPER
WAVE. THE UPPER WAVE WILL HAVE A WEAK JET STREAK WITH IT AND WILL
ALSO PROVIDE BROADER SCALE FORCING.
SHOWERS AND THUNDERSTORMS ARE DEVELOPING ACROSS MISSOURI AT THE
MOMENT. THESE WILL MOVE EAST INTO THE AREA THIS MORNING. THEY WILL
FIRST HAVE TO OVERCOME THE DRY AIR AT THE SURFACE...BUT THIS IS
BEING DONE QUICKLY AT THE MOMENT ACROSS NORTHERN MISSOURI.
WITH THE RAINFALL ALREADY DEVELOPING TO THE WEST...AND MULTIPLE
SOURCES OF LIFT MOVING ACROSS THE FORECAST AREA...WENT AHEAD AND
WENT LIKELY POPS ALL AREAS TODAY. SOME MODELS ARE HINTING AT SOME
DRY HOURS AGAIN DURING PART OF THE AFTERNOON...BUT CONFIDENCE IN
TIMING IS TOO LOW TO TRY AND PUT THIS DETAIL IN THE FORECAST AT THE
MOMENT.
GRIDDED MOS GUIDANCE LOOKS REASONABLE FOR HIGH TEMPERATURES
TODAY...SO STUCK CLOSE.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
ISSUED AT 303 AM EDT TUE SEP 25 2012
FOCUS IS ON CHANCES FOR RAIN THROUGH THE PERIOD. MODELS ARE IN
DECENT AGREEMENT WITH OVERALL PATTERN...ALTHOUGH SOME HAVE
DIFFERENCES IN LOCATION OF FRONT. A BLEND OF MODELS LOOKS BEST GIVEN
UNCERTAINTIES IN FRONTAL PLACEMENT LATER IN THE PERIOD.
WITH THE FRONT IN THE AREA TONIGHT AND FORCING CONTINUING...WENT
LIKELY POPS ALL AREAS AGAIN THIS EVENING. DID LOWER THE POPS SOME IN
THE NORTHWEST AFTER 06Z THOUGH AS THE FRONT SINKS SOUTH. TRENDED
TOWARD MAV MOS FOR LOW TEMPERATURES GIVEN THE CLOUDS AND RAINFALL.
AS THE FRONT SLOWLY SINKS ITS WAY SOUTH THROUGH THE REMAINDER OF THE
SHORT TERM...AND UPPER SUPPORT WEAKENS...GRADUALLY LOWERED POPS FROM
NORTH TO SOUTH AND GRADUALLY THROUGH TIME FOR THE REMAINDER OF THE
SHORT TERM.
FOR TEMPERATURES...STUCK FAIRLY CLOSE TO MAV MOS OR A BLEND OF
MET/MAV THROUGH THE PERIOD.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
ISSUED AT 234 AM EDT TUE SEP 25 2012
THE ONLY PERIOD THAT WILL INCLUDE RAIN CHANCES DURING THIS PERIOD
FOR NOW WILL BE SATURDAY AS A FRONTAL BOUNDARY IS EXPECTED TO BE
SAGGING SOUTHWARD OUT OF THE AREA DURING THE DAY. AS FOR THE REST OF
THE PERIOD...CONFIDENCE REMAINS LOW AS THE ECMWF KEEPS A FRONTAL
BOUNDARY FARTHER SOUTH OVER THE TENNESSEE VALLEY WITH BUILDING HIGH
PRESSURE FROM THE NORTH...WHILE THE GFS IS FARTHER NORTH WITH THE
FRONTAL BOUNDARY AND ALSO DROPS AN UPPER LOW OUT OF THE GREAT LAKES
OVER THE AREA. WITH MOISTURE APPEARING RATHER LIMITED IN EITHER CASE
AND A DRY LOWER LEVEL NORTHEAST FLOW PREVALENT IN BOTH CASES HAVE
TRENDED TOWARD A DRIER FORECAST DURING THIS TIME PERIOD FOR NOW.
&&
.AVIATION /DISCUSSION FOR THE 250900Z IND TAF UPDATE/...
ONGOING TAF IN GOOD SHAPE AS TSRA CONTINUE TO DEVELOP IN THE
MISSISSIPPI RIVER VALLEY AND MOVE EAST WITH AN ASSOCIATED SHORT
WAVE. RADAR TIME OF ARRIVAL TOOL INDICATE TSRA SHOULD REACH THE
IND AREA BY 13Z-15Z AND HAVE TRENDED THE ONGOING TAF IN THAT
MANNER. IN THE MEANTIME THE ONGOING VFR CIGS ARE GOOD TO GO.
PREVIOUS DISCUSSION BELOW
/DISCUSSION FOR 250600Z TAF ISSUANCE/... ISSUED AT 1200 AM EDT TUE
SEP 25 2012
VFR CONDITIONS EXPECTED THROUGH DAYBREAK...POSSIBLE PERIODS OF MVFR
CONDITIONS TUESDAY MORNING.
WARM ADVECTION HAS COMMENCED WITH A SLOWLY EXPANDING AREA OF
STRATOCU INTO THE FORECAST AREA. RAP SOUNDINGS AND RH PROGS INDICATE
THIS SHOULD CONTINUE TO EXPAND ACROSS THE TERMINALS OVER THE NEXT
FEW HOURS BEFORE POSSIBLY DIMINISHING TO A HIGHER MID LEVEL DECK FOR
A SHORT PERIOD OF TIME. AS STRONGER FORCING ALOFT AND ISENTROPIC
LIFT EXPAND INTO THE REGION TOWARDS DAYBREAK HOWEVER...LOWER
CEILINGS SHOULD REESTABLISH OVER CENTRAL INDIANA. OUTSIDE OF A FEW
SPRINKLES...EXPECT IT WILL TAKE UNTIL BETTER LIFT ARRIVES NEAR 12Z
FOR ANY SUBSTANTIAL PRECIP TO IMPACT THE TERMINALS.
WIDESPREAD RAINFALL IS ANTICIPATED BETWEEN 12 AND 18Z AS A MID LEVEL
SHORTWAVE MOVES THROUGH THE REGION. POTENTIAL FOR CEILINGS TO DIP
INTO MVFR CATEGORY WITHIN HEAVIER PRECIP DURING THE MORNING. ANY
CONVECTION LIKELY TO BE MORE SCATTERED IN COVERAGE DURING THE
AFTERNOON AS ADDITIONAL DISTURBANCES ALOFT TRACK THROUGH THE REGION.
HAVE HELD ONTO VCTS MENTION ALL AFTERNOON WITH UNSTABLE AIRMASS
PRESENT. AN EXPANSION IN CONVECTIVE COVERAGE WILL LIKELY OCCUR AGAIN
THIS EVENING AS A LOW LEVEL JET NOSES INTO THE REGION...AND WILL
CARRY PREVAILING SHOWERS WITH VCTS ONCE AGAIN AT ALL TERMINALS. S/SW
WINDS EXPECTED THROUGHOUT THE FORECAST PERIOD.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...50
SHORT TERM...50
LONG TERM....PUMA
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
303 AM EDT TUE SEP 25 2012
.UPDATE...
THE SYNOPSIS...NEAR TERM...AND SHORT TERM SECTIONS HAVE BEEN UPDATED
BELOW.
&&
.SYNOPSIS...
ISSUED AT 303 AM EDT TUE SEP 25 2012
A COUPLE OF FRONTS WILL MOVE INTO THE AREA AND LINGER THROUGH THE
END OF THE WORK WEEK...KEEPING CHANCES FOR RAIN ACROSS MUCH OF THE
AREA THROUGH THEN. HIGH PRESSURE WILL THEN BUILD IN AND KEEP MUCH OF
THE WEEKEND INTO EARLY NEXT WEEK DRY. TEMPERATURES WILL RETURN TO
BELOW AVERAGE BY THE WEEKEND.
&&
.NEAR TERM /TODAY/...
ISSUED AT 303 AM EDT TUE SEP 25 2012
ISENTROPIC LIFT WILL INCREASE ACROSS THE FORECAST AREA TODAY AS A
COUPLE OF FRONTAL SYSTEMS APPROACH THE AREA...ALONG WITH AN UPPER
WAVE. THE UPPER WAVE WILL HAVE A WEAK JET STREAK WITH IT AND WILL
ALSO PROVIDE BROADER SCALE FORCING.
SHOWERS AND THUNDERSTORMS ARE DEVELOPING ACROSS MISSOURI AT THE
MOMENT. THESE WILL MOVE EAST INTO THE AREA THIS MORNING. THEY WILL
FIRST HAVE TO OVERCOME THE DRY AIR AT THE SURFACE...BUT THIS IS
BEING DONE QUICKLY AT THE MOMENT ACROSS NORTHERN MISSOURI.
WITH THE RAINFALL ALREADY DEVELOPING TO THE WEST...AND MULTIPLE
SOURCES OF LIFT MOVING ACROSS THE FORECAST AREA...WENT AHEAD AND
WENT LIKELY POPS ALL AREAS TODAY. SOME MODELS ARE HINTING AT SOME
DRY HOURS AGAIN DURING PART OF THE AFTERNOON...BUT CONFIDENCE IN
TIMING IS TOO LOW TO TRY AND PUT THIS DETAIL IN THE FORECAST AT THE
MOMENT.
GRIDDED MOS GUIDANCE LOOKS REASONABLE FOR HIGH TEMPERATURES
TODAY...SO STUCK CLOSE.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
ISSUED AT 303 AM EDT TUE SEP 25 2012
FOCUS IS ON CHANCES FOR RAIN THROUGH THE PERIOD. MODELS ARE IN
DECENT AGREEMENT WITH OVERALL PATTERN...ALTHOUGH SOME HAVE
DIFFERENCES IN LOCATION OF FRONT. A BLEND OF MODELS LOOKS BEST GIVEN
UNCERTAINTIES IN FRONTAL PLACEMENT LATER IN THE PERIOD.
WITH THE FRONT IN THE AREA TONIGHT AND FORCING CONTINUING...WENT
LIKELY POPS ALL AREAS AGAIN THIS EVENING. DID LOWER THE POPS SOME IN
THE NORTHWEST AFTER 06Z THOUGH AS THE FRONT SINKS SOUTH. TRENDED
TOWARD MAV MOS FOR LOW TEMPERATURES GIVEN THE CLOUDS AND RAINFALL.
AS THE FRONT SLOWLY SINKS ITS WAY SOUTH THROUGH THE REMAINDER OF THE
SHORT TERM...AND UPPER SUPPORT WEAKENS...GRADUALLY LOWERED POPS FROM
NORTH TO SOUTH AND GRADUALLY THROUGH TIME FOR THE REMAINDER OF THE
SHORT TERM.
FOR TEMPERATURES...STUCK FAIRLY CLOSE TO MAV MOS OR A BLEND OF
MET/MAV THROUGH THE PERIOD.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
ISSUED AT 234 AM EDT TUE SEP 25 2012
THE ONLY PERIOD THAT WILL INCLUDE RAIN CHANCES DURING THIS PERIOD
FOR NOW WILL BE SATURDAY AS A FRONTAL BOUNDARY IS EXPECTED TO BE
SAGGING SOUTHWARD OUT OF THE AREA DURING THE DAY. AS FOR THE REST OF
THE PERIOD...CONFIDENCE REMAINS LOW AS THE ECMWF KEEPS A FRONTAL
BOUNDARY FARTHER SOUTH OVER THE TENNESSEE VALLEY WITH BUILDING HIGH
PRESSURE FROM THE NORTH...WHILE THE GFS IS FARTHER NORTH WITH THE
FRONTAL BOUNDARY AND ALSO DROPS AN UPPER LOW OUT OF THE GREAT LAKES
OVER THE AREA. WITH MOISTURE APPEARING RATHER LIMITED IN EITHER CASE
AND A DRY LOWER LEVEL NORTHEAST FLOW PREVALENT IN BOTH CASES HAVE
TRENDED TOWARD A DRIER FORECAST DURING THIS TIME PERIOD FOR NOW.
&&
.AVIATION /DISCUSSION FOR 250600Z TAF ISSUANCE/...
ISSUED AT 1200 AM EDT TUE SEP 25 2012
VFR CONDITIONS EXPECTED THROUGH DAYBREAK...POSSIBLE PERIODS OF MVFR
CONDITIONS TUESDAY MORNING.
WARM ADVECTION HAS COMMENCED WITH A SLOWLY EXPANDING AREA OF
STRATOCU INTO THE FORECAST AREA. RAP SOUNDINGS AND RH PROGS INDICATE
THIS SHOULD CONTINUE TO EXPAND ACROSS THE TERMINALS OVER THE NEXT
FEW HOURS BEFORE POSSIBLY DIMINISHING TO A HIGHER MID LEVEL DECK FOR
A SHORT PERIOD OF TIME. AS STRONGER FORCING ALOFT AND ISENTROPIC
LIFT EXPAND INTO THE REGION TOWARDS DAYBREAK HOWEVER...LOWER
CEILINGS SHOULD REESTABLISH OVER CENTRAL INDIANA. OUTSIDE OF A FEW
SPRINKLES...EXPECT IT WILL TAKE UNTIL BETTER LIFT ARRIVES NEAR 12Z
FOR ANY SUBSTANTIAL PRECIP TO IMPACT THE TERMINALS.
WIDESPREAD RAINFALL IS ANTICIPATED BETWEEN 12 AND 18Z AS A MID LEVEL
SHORTWAVE MOVES THROUGH THE REGION. POTENTIAL FOR CEILINGS TO DIP
INTO MVFR CATEGORY WITHIN HEAVIER PRECIP DURING THE MORNING. ANY
CONVECTION LIKELY TO BE MORE SCATTERED IN COVERAGE DURING THE
AFTERNOON AS ADDITIONAL DISTURBANCES ALOFT TRACK THROUGH THE REGION.
HAVE HELD ONTO VCTS MENTION ALL AFTERNOON WITH UNSTABLE AIRMASS
PRESENT. AN EXPANSION IN CONVECTIVE COVERAGE WILL LIKELY OCCUR AGAIN
THIS EVENING AS A LOW LEVEL JET NOSES INTO THE REGION...AND WILL
CARRY PREVAILING SHOWERS WITH VCTS ONCE AGAIN AT ALL TERMINALS. S/SW
WINDS EXPECTED THROUGHOUT THE FORECAST PERIOD.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...50
SHORT TERM...50
LONG TERM....PUMA
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
243 AM EDT TUE SEP 25 2012
.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 331 PM EDT MON SEP 24 2012
WARM ADVECTION WILL RAMP UP TONIGHT AND BRING WARMER TEMPERATURES TO
THE AREA. CHANCES FOR RAIN AND THUNDERSTORMS WILL ALSO ARRIVE LATE
TONIGHT WITH AN UPPER WAVE APPROACHING THE AREA. OVER THE COMING
DAYS A FRONT WILL STALL ACROSS CENTRAL INDIANA AND WAVES WILL MOVE
ALONG THIS FRONT KEEPING PRECIPITATION IN THE FORECAST FOR PARTS OF
THE AREA THROUGHOUT THE PERIOD. WITH COLDER AIR BOTTLED BACK UP TO
THE NORTH EXPECT TEMPERATURES TO BE CLOSE TO NORMAL FOR THIS TIME OF
YEAR.
&&
.NEAR TERM /REST OF TONIGHT/...
ISSUED AT 958 PM EDT MON SEP 24 2012
CUT OUT ALL POPS PRIOR TO 09Z...AND CUT POPS AFTER 09Z TO NO MORE
THAN 45 AND CONFINED ONLY TO SW HALF OF FORECAST AREA.
VERY DRY IN THE LOW LEVELS RIGHT NOW...AND THIS IS THE CASE ALL
THE WAY BACK INTO THE MID MISSISSIPPI VALLEY PER 00Z RAOBS. HAVING
A VERY HARD TIME SEEING CURRENT MID 30S TO LOW 40S DEWPOINTS
MOISTENING UP ENOUGH FOR MORE THAN A CHANCE OF PRECIP LATE.
A LOW LEVEL JET AXIS DOES RAMP UP TO OUR SW LATER TONIGHT...BUT
NEVER QUITE MAKES IT TO THE AREA PRIOR TO 12Z...AND WILL BE
ADVECTING A FAIRLY DRY AIRMASS ACCORDING TO AFOREMENTIONED RAOBS.
THIS ALSO REQUIRED A CUT TO OVERNIGHT LOWS AS WELL...AS LOWER THAN
EXPECTED DEWPOINTS AND LATER CLOUD COVER/POSSIBLE PRECIP WILL
ALLOW TEMPS TO DROP INTO THE UPPER 40S TO AROUND 50. MAV GUIDANCE
APPEARS TO HANDLE THIS WELL AND WAS USED.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
ISSUED AT 331 PM EDT MON SEP 24 2012
FORECAST FOCUS IS ON POPS. TUESDAY STARTS OUT WITH A LOW LEVEL JET
POINTING AT AND THEN TRAVERSING CENTRAL INDIANA. THIS WILL BRING
ISENTROPIC LIFT ACROSS THE AREA AND ALONG WITH A SHORTWAVE MOVING
ACROSS THE STATE SHOULD BE PLENTY OF FORCING FOR PRECIP. WENT HIGHER
WITH POPS IN SOME PLACES TO KEEP LIKELY GOING ACROSS THE AREA AND
INCLUDED CHANCES FOR THUNDERSTORMS BASED ON INCREASING ELEVATED
INSTABILITY. WITH ELEVATED INSTABILITY AND LOW END SHEAR IN PLACE
COULD SEE SOME MARGINAL HAIL. PRECIPITATION CHANCES LOOK EVEN BETTER
FOR TUESDAY NIGHT WITH A LOW LEVEL JET INCREASING IN STRENGTH AND
SETTING UP JUST TO THE SOUTHWEST. LOOKS LIKE ANOTHER SHORTWAVE WILL
BE MOVING THROUGH AND A FRONT WILL BE SAGGING SOUTH INTO THE AREA.
WITH THESE FEATURES COMBINING INCREASED GUIDANCE POPS TO CATEGORICAL
ACROSS ALL BUT THE NORTH. ON WEDNESDAY KEPT LIKELY POPS GOING SOUTH
OF THE FRONT AND KEPT HIGH CHANCE POPS IN THE SOUTHERN COUNTIES FOR
WEDNESDAY NIGHT WITH THE FRONT STALLING OUT NEAR OR JUST SOUTH OF
THERE. WITH GOOD INSTABILITY SHOWING UP FROM TUESDAY THROUGH
WEDNESDAY KEPT CHANCE FOR THUNDER GOING...DECREASING TO A SLIGHT
CHANCE FOR THUNDER WEDNESDAY NIGHT AND THURSDAY AS FRONT MAY BE
SOUTH OF THE AREA.
FOR TEMPERATURES...GENERALLY FAVORED WARMER GUIDANCE AT NIGHT WITH
WARM ADVECTION...RAIN...AND CLOUD COVER. FOR DAYTIME HIGHS USED A
GUIDANCE AVERAGE.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
ISSUED AT 234 AM EDT TUE SEP 25 2012
THE ONLY PERIOD THAT WILL INCLUDE RAIN CHANCES DURING THIS PERIOD
FOR NOW WILL BE SATURDAY AS A FRONTAL BOUNDARY IS EXPECTED TO BE
SAGGING SOUTHWARD OUT OF THE AREA DURING THE DAY. AS FOR THE REST
OF THE PERIOD...CONFIDENCE REMAINS LOW AS THE ECMWF KEEPS A
FRONTAL BOUNDARY FARTHER SOUTH OVER THE TENNESSEE VALLEY WITH
BUILDING HIGH PRESSURE FROM THE NORTH...WHILE THE GFS IS FARTHER
NORTH WITH THE FRONTAL BOUNDARY AND ALSO DROPS AN UPPER LOW OUT OF
THE GREAT LAKES OVER THE AREA. WITH MOISTURE APPEARING RATHER
LIMITED IN EITHER CASE AND A DRY LOWER LEVEL NORTHEAST FLOW
PREVALENT IN BOTH CASES HAVE TRENDED TOWARD A DRIER FORECAST
DURING THIS TIME PERIOD FOR NOW.
&&
.AVIATION /DISCUSSION FOR 250600Z TAF ISSUANCE/...
ISSUED AT 1200 AM EDT TUE SEP 25 2012
VFR CONDITIONS EXPECTED THROUGH DAYBREAK...POSSIBLE PERIODS OF MVFR
CONDITIONS TUESDAY MORNING.
WARM ADVECTION HAS COMMENCED WITH A SLOWLY EXPANDING AREA OF
STRATOCU INTO THE FORECAST AREA. RAP SOUNDINGS AND RH PROGS INDICATE
THIS SHOULD CONTINUE TO EXPAND ACROSS THE TERMINALS OVER THE NEXT
FEW HOURS BEFORE POSSIBLY DIMINISHING TO A HIGHER MID LEVEL DECK FOR
A SHORT PERIOD OF TIME. AS STRONGER FORCING ALOFT AND ISENTROPIC
LIFT EXPAND INTO THE REGION TOWARDS DAYBREAK HOWEVER...LOWER
CEILINGS SHOULD REESTABLISH OVER CENTRAL INDIANA. OUTSIDE OF A FEW
SPRINKLES...EXPECT IT WILL TAKE UNTIL BETTER LIFT ARRIVES NEAR 12Z
FOR ANY SUBSTANTIAL PRECIP TO IMPACT THE TERMINALS.
WIDESPREAD RAINFALL IS ANTICIPATED BETWEEN 12 AND 18Z AS A MID LEVEL
SHORTWAVE MOVES THROUGH THE REGION. POTENTIAL FOR CEILINGS TO DIP
INTO MVFR CATEGORY WITHIN HEAVIER PRECIP DURING THE MORNING. ANY
CONVECTION LIKELY TO BE MORE SCATTERED IN COVERAGE DURING THE
AFTERNOON AS ADDITIONAL DISTURBANCES ALOFT TRACK THROUGH THE REGION.
HAVE HELD ONTO VCTS MENTION ALL AFTERNOON WITH UNSTABLE AIRMASS PRESENT.
AN EXPANSION IN CONVECTIVE COVERAGE WILL LIKELY OCCUR AGAIN THIS
EVENING AS A LOW LEVEL JET NOSES INTO THE REGION...AND WILL CARRY
PREVAILING SHOWERS WITH VCTS ONCE AGAIN AT ALL TERMINALS. S/SW WINDS
EXPECTED THROUGHOUT THE FORECAST PERIOD.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CP
NEAR TERM...NIELD
SHORT TERM...CP
LONG TERM....PUMA
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1200 AM EDT TUE SEP 25 2012
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 331 PM EDT MON SEP 24 2012
WARM ADVECTION WILL RAMP UP TONIGHT AND BRING WARMER TEMPERATURES TO
THE AREA. CHANCES FOR RAIN AND THUNDERSTORMS WILL ALSO ARRIVE LATE
TONIGHT WITH AN UPPER WAVE APPROACHING THE AREA. OVER THE COMING
DAYS A FRONT WILL STALL ACROSS CENTRAL INDIANA AND WAVES WILL MOVE
ALONG THIS FRONT KEEPING PRECIPITATION IN THE FORECAST FOR PARTS OF
THE AREA THROUGHOUT THE PERIOD. WITH COLDER AIR BOTTLED BACK UP TO
THE NORTH EXPECT TEMPERATURES TO BE CLOSE TO NORMAL FOR THIS TIME OF
YEAR.
&&
.NEAR TERM /REST OF TONIGHT/...
ISSUED AT 958 PM EDT MON SEP 24 2012
CUT OUT ALL POPS PRIOR TO 09Z...AND CUT POPS AFTER 09Z TO NO MORE
THAN 45 AND CONFINED ONLY TO SW HALF OF FORECAST AREA.
VERY DRY IN THE LOW LEVELS RIGHT NOW...AND THIS IS THE CASE ALL
THE WAY BACK INTO THE MID MISSISSIPPI VALLEY PER 00Z RAOBS. HAVING
A VERY HARD TIME SEEING CURRENT MID 30S TO LOW 40S DEWPOINTS
MOISTENING UP ENOUGH FOR MORE THAN A CHANCE OF PRECIP LATE.
A LOW LEVEL JET AXIS DOES RAMP UP TO OUR SW LATER TONIGHT...BUT
NEVER QUITE MAKES IT TO THE AREA PRIOR TO 12Z...AND WILL BE
ADVECTING A FAIRLY DRY AIRMASS ACCORDING TO AFOREMENTIONED RAOBS.
THIS ALSO REQUIRED A CUT TO OVERNIGHT LOWS AS WELL...AS LOWER THAN
EXPECTED DEWPOINTS AND LATER CLOUD COVER/POSSIBLE PRECIP WILL
ALLOW TEMPS TO DROP INTO THE UPPER 40S TO AROUND 50. MAV GUIDANCE
APPEARS TO HANDLE THIS WELL AND WAS USED.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
ISSUED AT 331 PM EDT MON SEP 24 2012
FORECAST FOCUS IS ON POPS. TUESDAY STARTS OUT WITH A LOW LEVEL JET
POINTING AT AND THEN TRAVERSING CENTRAL INDIANA. THIS WILL BRING
ISENTROPIC LIFT ACROSS THE AREA AND ALONG WITH A SHORTWAVE MOVING
ACROSS THE STATE SHOULD BE PLENTY OF FORCING FOR PRECIP. WENT HIGHER
WITH POPS IN SOME PLACES TO KEEP LIKELY GOING ACROSS THE AREA AND
INCLUDED CHANCES FOR THUNDERSTORMS BASED ON INCREASING ELEVATED
INSTABILITY. WITH ELEVATED INSTABILITY AND LOW END SHEAR IN PLACE
COULD SEE SOME MARGINAL HAIL. PRECIPITATION CHANCES LOOK EVEN BETTER
FOR TUESDAY NIGHT WITH A LOW LEVEL JET INCREASING IN STRENGTH AND
SETTING UP JUST TO THE SOUTHWEST. LOOKS LIKE ANOTHER SHORTWAVE WILL
BE MOVING THROUGH AND A FRONT WILL BE SAGGING SOUTH INTO THE AREA.
WITH THESE FEATURES COMBINING INCREASED GUIDANCE POPS TO CATEGORICAL
ACROSS ALL BUT THE NORTH. ON WEDNESDAY KEPT LIKELY POPS GOING SOUTH
OF THE FRONT AND KEPT HIGH CHANCE POPS IN THE SOUTHERN COUNTIES FOR
WEDNESDAY NIGHT WITH THE FRONT STALLING OUT NEAR OR JUST SOUTH OF
THERE. WITH GOOD INSTABILITY SHOWING UP FROM TUESDAY THROUGH
WEDNESDAY KEPT CHANCE FOR THUNDER GOING...DECREASING TO A SLIGHT
CHANCE FOR THUNDER WEDNESDAY NIGHT AND THURSDAY AS FRONT MAY BE
SOUTH OF THE AREA.
FOR TEMPERATURES...GENERALLY FAVORED WARMER GUIDANCE AT NIGHT WITH
WARM ADVECTION...RAIN...AND CLOUD COVER. FOR DAYTIME HIGHS USED A
GUIDANCE AVERAGE.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
ISSUED AT 216 PM EDT MON SEP 23 2012
MAIN FOCUS WITH THE EXTENDED WITH BE POPS AND TEMPERATURES. MODELS
ARE NOW IN A BIT CLOSER AGREEMENT ON SLIDING AN UPPER TROUGH
SOUTHEAST ACROSS THE OHIO VALLEY LATE IN THE WEEKEND AND EARLY NEXT
WEEK AS IT PHASES WITH THE PERSISTENT EASTERN CANADIAN VORTEX. THIS
SHOULD KEEP THE MIDWEEK FRONT WELL SOUTH OF CENTRAL INDIANA ACROSS
THE SOUTHERN STATES THROUGH THE EXTENDED. HOWEVER...HPC IS
SUGGESTING A SECONDARY FRONT MAY MOVE THROUGH THE AREA FRIDAY
NIGHT..AND SEVERAL UPPER WAVES WILL DROP SOUTHEAST ACROSS THE OHIO
VALLEY IN NORTHWEST FLOW ON THE BACK SIDE OF THE TROUGH.
SO...DESPITE THE MODELS ALL GOING WITH LITTLE TO ANY QPF AFTER
FRIDAY...WILL GENERALLY ACCEPT THE LOW POPS FOR MOST PERIODS FROM
THE CENTRAL REGION INITIALIZATION. MODEL TO MODEL AND MODEL VERSUS
MODEL CONSISTENCY HAS JUST NOT BEEN GOOD ENOUGH TO DEVIATE MUCH AWAY
FROM THEM IN EITHER POPS OR TEMPERATURES. WITH THAT IN MIND...WILL
STICK WITH THE SLIGHTLY BELOW TEMPERATURES AS WELL FROM THE CR INIT.
&&
.AVIATION /DISCUSSION FOR 250300Z TAF UPDATE/...
ISSUED AT 1200 AM EDT TUE SEP 25 2012
VFR CONDITIONS EXPECTED THROUGH DAYBREAK...POSSIBLE PERIODS OF MVFR
CONDITIONS TUESDAY MORNING.
WARM ADVECTION HAS COMMENCED WITH A SLOWLY EXPANDING AREA OF
STRATOCU INTO THE FORECAST AREA. RAP SOUNDINGS AND RH PROGS INDICATE
THIS SHOULD CONTINUE TO EXPAND ACROSS THE TERMINALS OVER THE NEXT
FEW HOURS BEFORE POSSIBLY DIMINISHING TO A HIGHER MID LEVEL DECK FOR
A SHORT PERIOD OF TIME. AS STRONGER FORCING ALOFT AND ISENTROPIC
LIFT EXPAND INTO THE REGION TOWARDS DAYBREAK HOWEVER...LOWER
CEILINGS SHOULD REESTABLISH OVER CENTRAL INDIANA. OUTSIDE OF A FEW
SPRINKLES...EXPECT IT WILL TAKE UNTIL BETTER LIFT ARRIVES NEAR 12Z
FOR ANY SUBSTANTIAL PRECIP TO IMPACT THE TERMINALS.
WIDESPREAD RAINFALL IS ANTICIPATED BETWEEN 12 AND 18Z AS A MID LEVEL
SHORTWAVE MOVES THROUGH THE REGION. POTENTIAL FOR CEILINGS TO DIP
INTO MVFR CATEGORY WITHIN HEAVIER PRECIP DURING THE MORNING. ANY
CONVECTION LIKELY TO BE MORE SCATTERED IN COVERAGE DURING THE
AFTERNOON AS ADDITIONAL DISTURBANCES ALOFT TRACK THROUGH THE REGION.
HAVE HELD ONTO VCTS MENTION ALL AFTERNOON WITH UNSTABLE AIRMASS PRESENT.
AN EXPANSION IN CONVECTIVE COVERAGE WILL LIKELY OCCUR AGAIN THIS
EVENING AS A LOW LEVEL JET NOSES INTO THE REGION...AND WILL CARRY
PREVAILING SHOWERS WITH VCTS ONCE AGAIN AT ALL TERMINALS. S/SW WINDS
EXPECTED THROUGHOUT THE FORECAST PERIOD.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...CP
NEAR TERM...NIELD
SHORT TERM...CP
LONG TERM....MK
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
512 AM EDT TUE SEP 25 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 511 AM EDT TUE SEP 25 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS CONTINUE TO SHOW A TROF OVER SE
CANADA INTO THE NE CONUS. REINFORCING SHORTWAVE TROF DROPPED THRU
THE UPPER LAKES LAST EVENING...BRINGING ANOTHER PUSH OF COOLER AIR
INTO THE AREA. AFTER THE SURGE OF WARMER AIR YESTERDAY ON GUSTY W/SW
WINDS AHEAD OF SHORTWAVE...850MB TEMPS ARE BACK DOWN TO 0C ACROSS
LAKE SUPERIOR...BUT ARE STILL AROUND 5C OVER THE FAR SCNTRL FCST
AREA PER LATEST RUC ANALYSIS. RELATIVELY DRY AIR HAS ALSO FOLLOWED
SHORTWAVE INTO UPPER MI...BUT UPSTREAM CWPL SOUNDING AT 00Z SHOWED
NEAR SATURATION FROM ABOUT 900MB TO 700MB. ALTHOUGH RECENT SATELLITE
IMAGERY SHOWS A SLIGHT INCREASE IN LAKE EFFECT CLOUDS...COVERAGE IS
STILL VERY LIMITED. NO SHRA ARE EVIDENT. TO THE N...CANADIAN RADARS
SHOW SOME -SHRA OFF LAKE NIPIGON.
MAIN CONCERN IN THE SHORT TERM WILL MAINLY BE LAKE EFFECT SHRA
POTENTIAL. SHORTWAVE UPSTREAM IN ERN MANITOBA AND FOLLOWING PIECE OF
ENERGY A LITTLE FARTHER N WILL BE ENHANCING FACTORS FOR SHRA
DEVELOPMENT. WITH DEEP LAYER FORCING PER QVECTORS SPREADING OVER THE
AREA TODAY ALONG WITH AN INCREASE IN LOW-LEVEL MOISTURE...EXPECT SOME
-SHRA DEVELOPMENT...BUT THE DISRUPTION OF LAKE EFFECT PROCESSES BY
DAYTIME HEATING WILL BE A SIGNIFICANT NEGATIVE FACTOR. PERIODIC
HEAVY WAVE ACTION ON LAKE SUPERIOR OVER THE LAST WEEK OR SO HAS
RESULTED IN MID LAKE WATER TEMPS FALLING TO 10-13C WHILE READINGS
AROUND 15-16C ARE PROBABLY STILL MORE COMMON OVER THE SRN PORTION OF
THE LAKE. SO OVERWATER INSTABILITY IS A LITTLE MORE MARGINAL...
ESPECIALLY FOR THE MORE DISRUPTIVE DAYTIME HRS. AT THIS POINT...
NOTHING MORE THAN SCHC POPS APPEAR WARRANTED...MAINLY OVER THE
NCNTRL FCST AREA AS DRIER AIR TO THE W SHOULD PREVENT ANY SHRA
DEVELOPMENT OFF WRN LAKE SUPERIOR.
SHRA COVERAGE SHOULD TEND TO INCREASE LATE TONIGHT AS 850MB TEMPS
FALL TOWARD -2C AND A WEAK SFC TROF DROPS S ACROSS THE LAKE IN
ASSOCIATION WITH SHORTWAVE. TIMING OF TROF WILL ALSO COINCIDE WITH
THE MORE FAVORABLE MIN OF THE DIURNAL CYCLE. THUS...HAVE POPS
INCREASING TO CHC OVER THE NCNTRL/NE FCST AREA LATE TONIGHT. LEFT
THE W DRY DUE TO LARGER AREA OF COOLER WATER OVER THE WRN LAKE AND
DUE TO DEEP LAYER QVECTOR DIVERGENCE DOMINATING. SOME OF THE HIGH
RES MODEL GUIDANCE INDICATES -SHRA WILL OCCUR OVER THE W...SO WILL
NEED TO REEXAMINE POTENTIAL AGAIN IN LATER FCSTS. IN THE INTERIOR W
TONIGHT...THERE SHOULD BE A SUFFICIENT LACK OF CLOUDS TO ALLOW TEMPS
TO FALL TO AROUND 30F...RESULTING IN FROST DEVELOPMENT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 511 AM EDT TUE SEP 25 2012
SHORTWAVE WILL BE EXITING THE CWA TO THE SE AT THE START OF THE
PERIOD...SETTING UP A PERIOD OF SPLIT FLOW THROUGH THE END OF THE
WEEK. THE NRN STREAM WILL BE SET IN CANADA...WHILE THE SRN STREAM
WILL BE OVER THE SRN HALF OF THE CONUS. THIS WILL ALLOW FOR HIGH
PRESSURE TO SETTLE IN AND PRODUCE A FAIRLY DRY LONG TERM PERIOD.
FORCING FROM THE SHORTWAVE...COMBINING WITH A POCKET OF LLVL
MOISTURE...SHOULD ALLOW SHOWERS TO BE ONGOING OVER SCNTRL/ERN LAKE
SUPERIOR AND ERN UPPER MI. THESE SHOWERS WILL BE AIDED BY ENHANCED
LLVL CONVERGENCE AND INCREASED LK INSTABILITY WITH H850 TEMPS AROUND
1C. THE SHOWERS SHOULD CONTINUE THROUGH MUCH OF THE MORNING...BUT
HIGH PRESSURE BUILDING IN AND THE QUICKLY EXITING SHORTWAVE/MOISTURE
SHOULD BRING A DIMINISHING TREND IN THE EARLY AFTERNOON.
ANTICYCLONIC FLOW INCREASING THROUGH THE DAY AND DRYING ALOFT
LOWERING THE CAPPING INVERSION WILL ALSO DIMINISH THE SHOWERS. WITH
THE CLOUDS IN PLACE FOR MUCH OF THE DAY...EXPECT HIGHS TO ONLY RISE
INTO THE 50S...WITH THE COOLEST VALUES OVER THE N WHERE THE CLOUD
COVER WILL BE THE THICKEST.
THIS HIGH WILL REMAIN IN PLACE THROUGH AT LEAST THURS NIGHT AND LEAD
TO DRY WX OVER UPPER MI. EXPECT A COLD NIGHT WED NIGHT WITH THE HIGH
BEING NEARLY OVERHEAD. PWATS AROUND 50 PERCENT OF NORMAL AND CLEAR
SKIES WILL PROMOTE RADIATIONAL COOLING AND EXPECT LOWS IN THE UPPER
20S AND LOWER 30S OVER MOST INTERIOR LOCATIONS. THIS WILL PRODUCE
ANOTHER DECENT FROST/FREEZE ACROSS THE AREA. SINCE MOST INTERIOR
LOCATIONS HAVE SEEN A FROST OR FREEZE ALREADY THIS MONTH...OUR
ADVISORY/WARNING HEADLINES HAVE ENDED...BUT WILL CONTINUE TO MENTION
FROST DURING THE TRANSITION PERIOD.
OTHER THAN SOME DIURNAL CU OVER THE SE HALF OF UPPER MI THURS
AFTN...EXPECT MOSTLY CLEAR SKIES TO CONTINUE ON THURS AND INTO FRI.
GRADUALLY WARMING H850 TEMPS WILL LEAD TO HIGHS RISING INTO THE 60S
FOR THURS/FRI...WHICH IS BACK TO NORMAL.
THE GREATEST UNCERTAINTY FOR THE LONG TERM FORECAST COMES WITH THE
SHORTWAVE THAT MOVES THROUGH THE NRN STREAM IN ONTARIO ON FRI. THIS
WILL DRAG A WEAK COLD FRONT ACROSS UPPER MI LATE THURS NIGHT AND
INTO FRI...BUT WILL ONLY CAUSE A SLIGHT WINDSHIFT.
THEN...DETERMINISTIC AND ENSEMBLE MODELS ARE STARTING TO TREND
TOWARDS THE SHORTWAVE BECOMING CLOSED/CUT OFF OVER FAR SE ONTARIO ON
SAT AND SLOWLY DRIFTING SSW INTO THE GREAT LKS. CONFIDENCE IS
INCREASING ON THIS OCCURRENCE...BUT THE LOCATION VARIES DEPENDING
ON THE MODEL. AT THIS POINT...WITH MOISTURE NOT EXPECTED TO BE TOO
FAR FROM THE SHORTWAVE WHILE MOVING THROUGH ONTARIO...DON/T THINK
THERE WILL BE MUCH MOISTURE TO WORK WITH WHEN THE TROUGH CUTS OFF.
THEREFORE...WILL CONTINUE TO FOLLOW A DRY FORECAST FOR THE WEEKEND
AS THE GENERAL CONSENSUS OF THE MODELS HAS THE UPPER LOW CENTERED
OVER LK HURON AND WEAK HIGH PRESSURE OVER THE CWA. RIGHT NOW
TEMPERATURES APPEAR TO BE SEASONABLE FOR THE END OF THE WORK WEEK
AND INTO THE WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 138 AM EDT TUE SEP 25 2012
VFR CONDITIONS ARE EXPECTED TO GIVE WAY TO SOME MVFR CIGS AS
LOW-LEVEL MOISTURE/MVFR CIGS CURRENTLY ACROSS NRN MANITOBA/NRN
ONTARIO SETTLES INTO THE UPPER LAKES. WITH MOISTURE AND INCREASING
OVER WATER INSTABILITY...MVFR CIGS WERE INCLUDED AT KSAW LATE. MORE
DIVERGENT LOW-LEVEL FLOW SHOULD KEEP KIWD AND KCMX VFR THRU THE END
OF THE FCST PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 511 AM EDT TUE SEP 25 2012
HIGH PRES/WEAK PRES GRADIENT WILL GENERALLY DOMINATE FOR THE REST OF
THIS WEEK...RESULTING IN WINDS UNDER 20KT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...JLB
MARINE...ROLFSON
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1156 PM CDT MON SEP 24 2012
.UPDATE...
ISSUED AT 822 PM CDT MON SEP 24 2012
LATEST RUC AND HRRR CONTINUE TO SUPPORT CATEGORICAL POPS ALONG AND
NORTH OF INTERSTATE 70 BETWEEN 06Z AND 12Z. CONVECTIVE INITIATION
SHOULD OCCUR ACROSS NORTHWEST MISSOURI BETWEEN 04Z AND 06Z AND
QUICKLY GROW UPSCALE INTO A CONVECTIVE COMPLEX THAT WILL MOVE EAST
ACROSS THE NORTHERN HALF OF MISSOURI INTO CENTRAL/SOUTHWEST
ILLINOIS. NO MAJOR CHANGES MADE TO THE FORECAST.
CVKING
&&
.SHORT TERM...
ISSUED AT 251 PM CDT MON SEP 24 2012
(TONIGHT)
WHAT LOOKS TO BE A RATHER ACTIVE/WET WORK WEEK SHOULD BEGIN TONIGHT.
STRONG WARM/MOIST ADVECTION WILL COMMENCE OVER THE AREA AFTER DUSK
AS A 45-50 KT SOUTHWESTERLY LLJ DEVELOPS. UPPER LEVEL FORCING
MECHANISMS IN THE FORM OF DCPVA DOWNSTREAM OF A 500-HPA TROUGH AND
RIGHT ENTRANCE REGION OF A 60-KT UPPER LEVEL JET WILL HELP PROVIDE
UVM ON THE SYNOPTIC SCALE. THE COLLOCATION OF THESE AFOREMENTIONED
FORCING MECHANISMS LOOKS TO TAKE PLACE ALONG AND JUST NORTH OF THE
INTERSTATE 70 CORRIDOR IN MISSOURI AND I-64 CORRIDOR IN ILLINOIS.
HAVE PLACED CATEGORICAL POPS LATE TONIGHT IN THIS REGION TO ACCOUNT
FOR THIS. AFTER INVESTIGATING NWP SOUNDINGS...CONVECTION SHOULD BE
ROOTED ABOVE A STABLE NOCTURNAL INVERSION WITH SOME OF THE STRONGER
STORMS CAPABLE OF PRODUCING LARGE HAIL GIVEN STEEP MIDLEVEL LAPSE
RATES AND AMPLE ELEVATED CAPE WITHIN HAIL GROWTH ZONE.
FOLLOWED 0900 UTC SREF/1200 UTC NAM FAIRLY CLOSELY FOR POPS/QPF. FOR
LOW TEMPERATURES...DID NOT DEVIATE SUBSTANTIALLY FROM MOS OUTPUT.
DID GO A BIT ABOVE GUIDANCE IN FAR NORTHERN/SOUTHERN CWA WHERE
LOWEST POPS/QPF ARE LOCATED. ALSO TRIED MY BEST TO CAPTURE A W/E
ORIENTED AXIS OF COOLER LOW TEMPERATURES COLLOCATED WITH AXIS OF
HEAVIEST RAINFALL AND HIGHEST POPS TO ACCOUNT FOR POTENTIAL
EVAPORATIVE COOLING.
GOSSELIN
&&
.LONG TERM...
ISSUED AT 251 PM CDT MON SEP 24 2012
(TOMORROW THROUGH SUNDAY)
THE PRIMARY FCST ISSUE OVER THE NEXT FEW DAYS IS PCPN CHCS. THIS IS
A COMPLICATED FCST BECAUSE PCPN CHCS FOR EACH DAY WILL DEPEND TO
SOME EXTENT ON WHAT WILL HAVE HAPPENED THE PREVIOUS NIGHT...AND
THOSE KINDS OF MESOSCALE DETAILS ARE DIFFICULT TO PIN DOWN
ACCURATELY MORE THAN A FEW HOURS IN ADVANCE. THE BEST WAY TO
INTERPRET THE WIDESPREAD CHC POPS IN THIS FCST PCKG IS THAT PCPN IS
POSSIBLE ALMOST ANYWHERE EVEN THOUGH IT PROBABLY WILL NOT RAIN
EVERYWHERE.
ELEVATED CONVECTION IS EXPECTED TO BE ONGOING ACROSS PARTS OF THE
CWA AT 12Z TUE DUE TO A STRONG LLJ IMPINGING ON A N-S ORIENTED WMFNT
LOCATED WEST OF THE CWA AND AIDED BY LARGE SCALE ASCENT AHEAD OF
A WEAK SHORTWAVE. TSRA COVERAGE SHOULD DIMINISH THROUGH THE
MORNING ONCE THE LLJ BEGINS TO WEAKEN. A SFC LOW PRESSURE CENTER
RIDING ALONG THE QUASISTATIONARY FNT IN KS WILL MOVE INTO CENTRAL
MO AND PUSH THE WMFNT THROUGH THE CWA BY LATE TUE AFTN...KEEPING
THE QUASISTATIONARY BDRY IN PLACE ACROSS SRN IA OR NRN MO.
ALTHOUGH THIS WILL PLACE THE CWA IN THE WARM SECTOR FOR THE
AFTN...RESIDUAL CLOUDINESS FM OVERNIGHT CONVECTION SHOULD LIMIT
WIDESPREAD DESTABILIZATION ALTHOUGH ISO-SCT TSRA COULD STILL
DEVELOP ON TUE AFTN IF THERE ARE POCKETS OF CLRG...ESPECIALLY
GIVEN MODEL FCSTS OF FAVORABLE H7-H5 LAPSE RATES SPREADING ACROSS
THE AREA.
THE KEY ISSUE MODULATING PCPN CHCS BEYOND TUE AFTN WILL BE THE
LOCATION OF THE QUASISTATIONARY BDRY MENTIONED ABOVE. THERE WILL NOT
BE MUCH IN THE WAY OF UPPER LEVEL SUPPORT TO INFLUENCE ITS POSITION
THIS WEEK. A HIGH PRESSURE CENTER WILL BE SLIDING SEWD FM CANADA
INTO THE GRTLKS FM TUE THROUGH THU AND THE CIRCULATION AROUND THAT
SFC HIGH COMBINED WITH THE CIRCULATIONS AROUND PERIODIC SFC LOWS
WILL ACT TO SHARPEN THE TEMPERATURE CONTRAST ACROSS THE
QUASISTATIONARY BDRY AND LIMIT ITS NWD PROGRESS. AT THE SAME
TIME...CONVECTIVE INFLUENCES MAY END UP PUSHING THE EFFECTIVE FRONT
EVEN FARTHER SOUTH THAN INDICATED BY THE MODELS. FINALLY...THE
STRENGTH OF THE HIGH PRESSURE CENTER WILL ALSO INFLUENCE THE INITIAL
LOCATION OF THE BDRY.
ATTM MODELS ARE IN GOOD AGREEMENT THAT THE BDRY WILL BE LOCATED
RIGHT ALONG THE MO/IA BORDER FOR MOST OF TUE NIGHT. A BROAD SWLY LLJ
THEN DVLPS OVERNIGHT ALONG WITH PW VALUES OF 1.3 TO 1.5 INCHES WHICH
IS AROUND THE 75TH PERCENTILE FOR SEPT IN THIS PART OF THE COUNTRY.
CONCEPTUAL MODELS SUPPORT THE IDEA THAT A QUASISTATIONARY E-W BDRY
WITH A NOCTURNAL LLJ NEARLY PARALLEL TO IT AND ON ITS WARM SIDE
WOULD LEAD TO AN ELONGATED AREA OF PCPN VERY CLOSE TO THE BDRY.
GFS/NAM ALSO SUPPORT THIS IDEA WITH CORFIDI VECTORS POINTED
UPSTREAM...SUGGESTING THAT NEW CONVECTION WILL CONTINUOUSLY DVLP AND
MOVE ENEWD WITHIN THE OVERALL BAND OF PCPN. PCPN SHOULD CONTINUE
THROUGH AT LEAST PART OF WED MORNING UNTIL THE LLJ WEAKENS.
MODELS BEGIN TO DIFFER ON THE LOCATION OF THE BDRY BY WED/THU AND IT
IS ENTIRELY POSSIBLE THAT THE EFFECTIVE BDRY MAY HAVE BEEN PUSHED
FARTHER SOUTH THAN THE MODELS SUGGEST DUE TO OUTFLOW BDRYS FROM
OVERNIGHT CONVECTION ON THE PREVIOUS COUPLE OF NIGHTS. THERE IS
LITTLE EVIDENCE OF A LLJ ON WED NIGHT OR THU NIGHT HOWEVER THE BDRY
WILL STILL BE PRESENT AND FAVORABLY POSITIONED BENEATH THE LEFT EXIT
REGION OF A H25 JET ON THU NIGHT AND FRI NIGHT. ULTIMATELY...SCT
PCPN IS USUALLY A FAIR BET WITH A QUASISTATIONARY BDRY ACROSS THE
AREA AND EVEN A HINT OF FORCING...THEREFORE WILL CONTINUE WITH
SCHC-CHC POPS THROUGH AT LEAST FRI. BEYOND FRI...MODELS SHOW THAT
THE QUASISTATIONARY FNT WILL BE PUSHED SWD AS A CDFNT BEFORE
STALLING SOMEWHERE IN THE REGION BY THE WEEKEND...BRINGING COOLER
TEMPERATURES TO PARTS OF MO/IL LATE IN THE FCST PD.
KANOFSKY
&&
.AVIATION...
ISSUED AT 1148 PM CDT MON SEP 24 2012
AS THE LLJ INCREASES THRU TONIGHT...EXPECT TSRA TO DEVELOP AHEAD OF
THE SFC LOW ACROSS WRN AND CENTRAL MO AND SPREAD EWD OVER THE NEXT
FEW HOURS. TSRA SHUD TRAVEL ALONG AND JUST N OF I70. BELIEVE PREV TAFS
HAVE A GOOD HANDLE ON THIS TREND AND FEW CHANGES WERE MADE. TSRA
SHUD MOVE OUT OF REGION/DIMINISH TUES MORNING. BELIEVE TERMINALS
WILL BE DRY TUES INTO THE LATE AFTERNOON/EVENING HOURS. TSRA SHUD
DEVELOP ALONG THE STATIONARY SFC FNT...BUT EXACT LOCATION IS
QUESTIONABLE AND WILL LIKELY DEPEND SOMEWHAT ON CONVECTION THIS
MORNING.
OTHERWISE...WINDS WILL BECOME SWLY S OF THE SFC FNT WITH GUSTS TO
20 KTS AT ALL TERMINALS EXCEPT FOR UIN. GUSTS MAY BE HIGHER
ESPECIALLY IN THE MORNING AS MIXING BEGINS. THESE GUSTS WILL
DIMINISH TUES EVENING WITH SUNSET. THE SFC FNT MAY MOVE S OF
COU/CPS/SUS TUES EVE...BUT WINDS MAY BE ERRATIC DUE TO TSRA.
SPECIFICS FOR KSTL...FEW CHANGES TO THE PREV TAF. STILL EXPECT
TSRA TO IMPACT TERMINAL LATE TONIGHT THRU DAWN TUES. EXPECT TSRA
TO DIMINISH/MOVE E OF TERMINAL SHORTLY AFTER SUNRISE. REGION SHUD
REMAIN DRY THRU MUCH OF THE DAY WITH THE NEXT ROUND OF TSRA
INITIATING TUES LATE AFTERNOON/EVENING ALONG STATIONARY SFC FNT.
BELIEVE BEST CHANCES FOR TSRA TUES EVE. WILL LET FUTURE UPDATES
HANDLE THIS ROUND OF PRECIP AS LOCATION OF THE SFC FNT WILL
DETERMINE TIMING AND IMPACT ON TERMINAL. OTHERWISE...WINDS WILL BECOME
SWLY S OF THE SFC FNT TUES MORNING WITH GUSTS TO AROUND 20 KTS.
WINDS WILL DIMINISH WITH SUNSET.
TILLY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
151 AM EDT TUE SEP 25 2012
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL BEGIN TO APPROACH THE AREA TONIGHT.
A FRONTAL BOUNDARY WILL SETTLE INTO THE AREA KEEPING PRECIPITATION
CHANCES IN THE FORECAST FOR MUCH OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
SKIES ARE CLEAR ACROSS THE AREA THIS EVENING...BUT EXPECT TO SEE
AN INCREASE IN CLOUDS LATER TONIGHT AS A MID LEVEL SHORT WAVE
APPROACHES FROM THE WEST. AHEAD OF THIS...THE LOW LEVEL FLOW WILL
BACK SLIGHTLY AND WE WILL SEE SOME DEVELOPING ISENTROPIC LIFT
TOWARD DAYBREAK. THIS COULD LEAD TO A FEW SHOWERS LATE. THE 18Z NAM
AND LATEST RAP ARE BOTH SHOWING SOME WEAK ELEVATED INSTABILITIES
WORKING IN LATE TONIGHT TOO SO WILL HANG ON TO THUNDER WORDING
ALTHOUGH THINK THE CHANCE WILL BE PRETTY LOW.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/...
A FRONTAL BOUNDARY WILL APPROACH AND THEN MEANDER AROUND THE FA
THROUGH THE SHORT TERM TIME FRAME. THIS WILL ALLOW FOR OFF AND ON
PRECIPITATION THROUGH THIS TIME. THERE IS STILL SOME UNCERTAINTY
IN WHERE THE EXACT LOCATION OF THE BOUNDARY WILL BE HOWEVER CURRENT
INDICATIONS ARE THAT SOME LOCATIONS ACROSS CENTRAL PORTIONS OF THE
FA WILL HAVE THE POTENTIAL FOR AN INCH OR TWO OF RAIN THROUGH THE
SHORT TERM TIME FRAME. THE FRONTAL BOUNDARY WILL BEGIN TO MOVE
SOUTH BY THE END OF THE SHORT TERM ENDING PRECIPITATION CHANCES
ACROSS NORTHERN PORTIONS OF THE FA. WITH DECENT INSTABILITY ACROSS
THE AREA ON WEDNESDAY A FEW OF THE STORMS MAY BE STRONG TO SEVERE
WITH DAMAGING WINDS AND HAIL THE PRIMARY THREATS. HIGH TEMPERATURES
WILL GENERALLY BE IN THE 70S WITH LOWS IN THE 50S AND 60S.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
THERE IS UNCERTAINTY WHERE A NEARLY STATIONARY FRONT WILL SET UP.
BUT AT THIS POINT IT APPEARS THAT IT WILL BE CLOSE ENOUGH TO THE
SOUTHERN ZONES TO KEEP A CHANCE OF SHOWERS AND POSSIBLY SOME THUNDER
THURSDAY INTO FRIDAY. EXPECT THE BOUNDARY TO FINALLY GET PUSHED
FURTHER SOUTH AS HIGH PRESSURE BUILDS IN ON THE BACK SIDE OF A
DEVELOPING UPPER LOW. THIS SHOULD SPREAD DRIER AIR ACROSS THE REGION
FOR THE WEEKEND INTO MONDAY. TEMPERATURES WILL BE NEAR NORMAL
THROUGH THE PERIOD.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
WESTERLY FLOW ALOFT WITH A MID LEVEL SHORT WAVE TRACKING FROM THE
MID MISSISSIPPI VALLEY EARLY THIS MORNING ACROSS ILN/S FA DURING
THE DAY. AHEAD OF THIS FEATURE EXPECT TO SEE AN INCREASE IN HIGH
AND THEN MID LEVEL CLOUDS TOWARD SUNRISE. WITH ISENTROPIC LIFT
DEVELOPING A FEW SPRINKLES OR LIGHT RAIN SHOWERS WILL BE POSSIBLE
TOWARD SUNRISE...BUT THESE SHUD BE OPERATIONALLY INSIGNIFICANT WITH
VFR CONDITIONS CONTINUING. BETTER FORCING MOVES IN DURG THE DAY
WITH MARGINAL INSTBY DEVELOPING. SCATTERED SHOWERS AND A FEW
THUNDERSTORMS WILL BECOME MORE WIDESPREAD THROUGH THE LATE AFTERNOON
AND ESPECIALLY INTO TONIGHT. THERE CONTINUES TO BE SOME MODEL SOLN
DIFFERENCES AS TO EXACTLY WHERE THE BEST CHANCE FOR PCPN WILL
LINE UP. RIGHT NOW...IT APPEARS THAT NORTHERN PORTIONS OF OUR FA
MAY HAVE THE BETTER CHANCE DURG THE AFTN AND THEN CHANCES
IMPROVING ACRS ALL TAF SITES THIS EVENING. HAVE CONTINUED VFR CIGS
WITH PREVAILING SHOWERS DEVELOPING AND VCTS FOR THUNDER LATE IN
THE FCST PERIOD.
.OUTLOOK...THUNDERSTORMS AND MVFR CONDITIONS POSSIBLE THROUGH
WEDNESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...NOVAK
NEAR TERM...JGL
SHORT TERM...NOVAK
LONG TERM...
AVIATION...AR
AREA FORECAST DISCUSSION
NWS TULSA OK
1135 PM CDT MON SEP 24 2012
.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE VALID
PERIOD AT ALL AREA TAF SITES. WILL ADD PROB30 TSRA FOR
NORTHEAST OKLAHOMA TAF SITES AFTER 00Z.
&&
.PREV DISCUSSION... /ISSUED 942 PM CDT MON SEP 24 2012/
..UPDATE...
DISCUSSION...
LATEST RUC ANALYSIS SUGGEST THE ELEVATED FRONTAL ZONE WILL REMAIN
WELL TO OUR NORTH AND JUST EAST OF THE FORECAST AREA OVERNIGHT.
THUS WILL REMOVE OVERNIGHT THUNDERSTORM MENTION. WILL ALSO
INCREASE OVERNIGHT CLOUD COVER GIVEN DENSE CIRRUS CANOPY AND MAKE
MINOR ADJUSTMENT TO WIND SPEEDS. THE FIRE WEATHER WATCH WILL
REMAIN IN EFFECT FOR TUESDAY...WITH PORTIONS OF THE WATCH POSSIBLY
UPGRADED TO A RED FLAG WARNING PENDING NEW DATA TRENDS.
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...FIRE WEATHER WATCH FROM NOON TUESDAY TO 9 PM TUESDAY FOR OKZ049-
OKZ053-OKZ054-OKZ055-OKZ059-OKZ060-OKZ061-OKZ064-OKZ065-
OKZ066-OKZ067-OKZ070-OKZ071-OKZ073-OKZ074-OKZ075-OKZ076.
AR...NONE.
&&
$$
AVIATION...10
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
436 AM CDT TUE SEP 25 2012
.SHORT TERM...
THE WARM FRONT THAT WILL INFLUENCE WEATHER FOR MOST OF THE WEEK CONTINUES
TO MOVE NORTHEAST THIS MORNING AND IS CURRENTLY STRETCHING ACROSS THE
MID MISSISSIPPI VALLEY AND OHIO VALLEY. A FEW ASSOCIATED SHOWERS HAVE
BEEN MOVING SLOWLY OVER WESTERN KENTUCKY AND WESTERN TN THIS
MORNING. HRRR SHOWS THIS ACTIVITY PERSISTING AND MOVING INTO MIDDLE
TN LATER THIS MORNING. HOWEVER ANY PRECIP SHOULD REMAIN LIGHT AND
MAINLY IMPACT NORTHWESTERN MIDDLE TN. CLOUD COVER WILL INCREASE
TODAY WITH MAINLY HIGH AND MID CLOUDS MOVING IN AS THE FRONT
REMAINS STATIONARY TUESDAY NIGHT AND WEDNESDAY. DIDN`T VENTURE TOO FAR
FROM GUIDANCE AS FAR AS TEMPS GO. HIGHS WILL BE QUITE A BIT WARMER
TODAY THROUGH THURSDAY...AROUND THE MID 80S AS WE SIT IN THE WARM
SECTOR OF THE FRONT. NIGHT TIME LOWS EXPECTED TO BE IN THE LOW 60S
WITH AREAS ALONG THE PLATEAU IN THE UPPER 50S. BEST PRECIP CHANCES
WILL REMAIN NORTH OF THE MIDSTATE BUT KEPT SLIGHT CHANCE POPS IN
THE PICTURE FOR THE NORTHERN COUNTIES FROM WEDNESDAY MORNING
THROUGH THURSDAY NIGHT.
.LONG TERM...
MODELS CAN`T SEEM TO AGREE ON THE MOVEMENT OF THE FRONT TO THE
NORTH. THE NAM BRINGS THE FRONT DOWN TOWARD THE NORTHWESTERN
COUNTIES ON THURSDAY WHILE THE GFS KEEPS THE FRONT TO THE NORTH
OF THE MID- STATE UNTIL FRIDAY NIGHT. LEANED TOWARD THE GFS
SOLUTION, WITH CHANCE POPS MAKING AN APPEARANCE FRIDAY MORNING
ALONG THE NORTHERN PORTION OF OUR AREA AND INCREASING IN COVERAGE
AS SATURDAY APPROACHES. MODELS DO AGREE THAT THIS WEEKEND WILL BE
WET AS AN UPPER TROUGH DEEPENS OVER THE SOUTHEAST WITH THE UPPER
LOW MOVING TO THE WEST OF TN. KEPT CHANCE POPS THROUGHOUT THE
WEEKEND. THEN RAIN CHANCES DECREASES FROM WEST TO EAST AS THE MAIN
MOISTURE AXIS MOVES SLIGHTLY EAST MONDAY. WENT SLIGHTLY COOLER
THAN GUIDANCE ON THE TEMPS IN THE LONG TERM.
&&
.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE 84 60 86 62 / 10 10 10 10
CLARKSVILLE 85 61 86 61 / 30 10 20 20
CROSSVILLE 76 57 80 57 / 10 10 10 10
COLUMBIA 85 60 87 60 / 10 10 10 10
LAWRENCEBURG 84 59 87 60 / 10 05 10 10
WAVERLY 86 61 86 61 / 30 10 10 20
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
11
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
919 AM MDT TUE SEP 25 2012
.UPDATE...NO BIG CHANGES AT THIS TIME. PCPN MAY BE A BIT SLOER TO
DEVELOP THIS AFTERNOON...BUT NOT ENOUGH TO REFLECT ANY MAJOR
ADJUSTMENTS TO THE FORECAST AT THIS TIME. HRRR BRINGS AN INITIAL
BAND OF PCPN ACROSS SW TO NE ACROSS THE CWFA AFTER 18Z BUT THIS
MAY BE OVERDONE. NEXT BAND PROGGED TO MOVE ACROSS LATE THIS AFTN
AND EVENING.
&&
.AVIATION...DO NOT ANTICIPATE ANY MAJOR CHANGES IN THE UPCOMING
TAFS. MAY NEED TO ADJUST THE TIMING OF THE PCPN THIS AFTN AND
EVENING. ONLY ISSUE MAY INVOLVE THE INCLUSION OF VCTS THIS AFTN.
CAPES THIS AFTN ONLY IN THE 400-500 J/KG RANGE...SO MAY OPT TO GO
WITH JUST RAIN SHOWERS...AND DROP THE MENTION OF VCTS. WEAK SFC
WINDS SHOULD TRANSITION TO ENELY THIS AFTN...SO NO CHANGES THERE.
&&
.PREV DISCUSSION... /ISSUED 312 AM TUE SEP 25 2012/
SHORT TERM...AN UPER LEVEL LOW OVER UTAH WILL MOVE SLOWLY EASTWARD
INTO WRN CO BY THIS EVENING AND THEN REMAIN NEARLY STATIONARY
OVERNIGHT. ALTHOUGH THERE WILL BE ABUNDANT MOISTURE QG FIELDS ARE
WK THRU TONIGHT WITH SOME MINOR UPPER LEVEL DIVERGENCE. AT THIS
TIME WILL KEEP HIGHEST POPS IN THE MTNS AND HIGHER FOOTHILLS WITH
CHC POPS ESLEWHERE. TEMPS WILL BE COLD ENOUGH FOR SOME SNOW OVER
THE HIGHEST PEAKS. ACROSS NERN CO AFTN CAPES ARE FCST TO BE 500
J/KG OR LESS THIS AFTN SO AIRMASS IS ONLY MARGINALLY UNSTABLE WHICH
WILL LIMIT INTENSITY OF TSTMS. AS FOR HIGHS WILL KEEP READINGS IN
THE 70S ACROSS NERN CO WITH THE WARMEST READINGS OVER THE FAR NERN
PLAINS.
FOR TONIGHT AS MENTIONED ABV THE WEAK UPPER LEVEL LOW WILL REMAIN
OVER WRN CO. WILL CONTINUE TO SEE SHOWER ACTIVITY IN THE MTNS
THROUGH MIDNIGHT WITH DECREASIGN ACTIVITY THEREAFTER. OVER THE
PLAINS WILL SEE SCT SHOWERS AND A FEW TSTMS IN THE EARLY EVENING
HOURS WHICH SHOULD GRADUALLY END BY MIDNIGHT.
LONG TERM...MODELS SHOW A WEAKENING UPPER CLOSED LOW/UPPER TROUGH
OVER WESTERN AND NORTHERN COLORADO WEDNESDAY THROUGH THURSDAY. IT
MOVES LITTLE...WITH PRETTY WEAK FLOW ALOFT FOR THE CWA THROUGH
THURSDAY NIGHT. THE SYNOPTIC SCALE ENERGY ACCORDING TO THE QG
VERTICAL VELOCITY FIELDS IS VERY WEAK THROUGH THE PERIODS...UPWARD
INTO THURSDAY MORNING...THEN DOWNWARD. THE BOUNDARY LAYER FLOW HAS
A GENERAL WEAK EASTERLY COMPONENT TO IT ALL FOUR PERIODS. IT IS
MAINLY EAST TO SOUTHEAST OVER THE PLAINS. FOR MOISTURE...BOTH THE
GFS AND NAM SHOW QUITE A BIT WEDNESDAY AND WEDNESDAY NIGHT. THE NAM
CONTINUES THIS TREND INTO THURSDAY...WITH A BIT OF DRYING THURSDAY
NIGHT. THE GFS IS DRIER THAN THE NAM ON THURSDAY AND THURSDAY
NIGHT...BUT THERE IS STILL MOISTURE AROUND. QUITE A BIT MORE THAN
WE HAVE SEEN THE LAST MANY DAYS. PRECIPITABLE WATER VALUES ARE IN
THE 0.60 TO 0.85 INCH RANGE ALL FOUR PERIODS...NOT BAD FOR LATE
SEPTEMBER. THE MODELS HAVE CAPE AROUND BOTH WEDNESDAY AND THURSDAY
..MORE SO ON THE NAM...AND BETTER ON BOTH MODELS FOR THE PLAINS.
THE QPF FIELDS HAVE MEASURABLE PRECIPITATION OVER THE CWA WEDNESDAY
THROUGH THURSDAY NIGHT...THE GFS HAS THE MOST...OF COURSE. THERE IS
GENERALLY MORE PROGGED WEDNESDAY AFTERNOON AND NIGHT. CURRENT GFE
GRIDS HAVE PRETTY DECENT POPS GOING ON WEDNESDAY AND WEDNESDAY NIGHT
..WILL CHANGE LITTLE THERE. MAY UP THURSDAY`S POPS A BIT...
ESPECIALLY ON THE PLAINS DURING THE AFTERNOON AND EVENING. FOR
TEMPERATURES...WEDNESDAY`S HIGHS ARE 2-3 C COOLER THAN TODAY`S.
THURSDAY HIGH`S ARE 0-1 C WARMER THAN WEDNESDAY`S. FOR THE LATER
DAYS...FRIDAY THROUGH MONDAY...MODELS HAVE WEAK FLOW ALOFT FRIDAY
AND SATURDAY. BY SUNDAY AND MONDAY...UPPER RIDGE TO THE WEST AND
NORTH BRINGS NORTHERLY AND NORTHEASTERLY FLOW ALOFT TO THE CWA.
THERE WILL BE SOME MOISTURE AVAILABLE FRIDAY AND SATURDAY...BUT
SUNDAY AND MONDAY DRY OUT. TEMPERATURES LOOK TO BE AROUND SEASONAL
NORMALS.
AVIATION...WILL HAVE QUITE A BIT OF MID LVL CLOUD COVER THROUGH
TONIGHT WITH CEILINGS AROUND 10000 FT. OVERALL INSTABILITY THIS
AFTN INTO THE EARLY EVENING IS NOT THAT GREAT SO WILL JUST MENTION
VCTS AND HAVE A PROB GROUP FOR SHOWERS. CEILINGS AND VISBILITIES
SHOULD STAY ABV MVFR WITH ANY PCPN. WINDS EARLY THIS MORNING ARE
WLY AND ARE FCST TO BECOME LIGHT ENE BY 18Z. FOR TONIGHT WINDS WILL
BECOME MORE WSW BY EARLY EVENING. AT THIS TIME DO NOT EXPECT ANY
STRATUS FOR WED MORNING.
HYDROLOGY...THERE WILL BE A GOOD CHANCE OF SHOWERS AND A FEW
AFTERNOON THUNDERSTORMS HOWEVER RAINFALL RATES SHOULD BE UNDER ONE
QUARTER INCH PER HOUR SO THE THREAT OF FLASH FLOODING SHOULD BE LOW
IN THE BURN AREAS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...COOPER
LONG TERM....RJK
AVIATION...COOPER
AREA FORECAST DISCUSSION...UPDATED
NWS MELBOURNE FL
645 AM EDT TUE SEP 25 2012
.DISCUSSION...
UPDATE...DYNAMIC LIFT OVER THE COASTAL WATERS N OF THE CAPE IS BEING
ENHANCED BY A THIN MID LVL VORT BAND LYING N OF THE I-4 CORRIDOR.
H30-H20 DIVERGENCE FIELDS HAVE SHOWN A NOTABLE INCREASE OVER THE
PAST FEW HRS...AS HAS THE RADAR TRENDS. NLDN AND LDAR ARE EVEN
PICKING UP AN OCNL LTG STRIKE. AS SUCH...WILL UPDATE ZONES TO
REFLECT HIGHER SHRA/TSRA CHANCES OVER THE NRN HALF OF THE CWA.
TODAY-TONIGHT...
A LARGE HI PRES RIDGE SPANNING THE ERN SEABOARD AND THE DEEP SOUTH
WILL PUSH INTO THE W ATLC TODAY...GENERATING A DEEP AND STEADY E/NE
FLOW ACRS CENTRAL FL. LATEST RAP ANALYSIS SHOWS A TONGUE OF DRY AIR
LINGERING OVER THE CENTRAL PENINSULA S OF THE I-4 CORRIDOR...BUT
WITH DEEPER MOISTURE PUSHING DOWN THE ERN PANHANDLE PENINSULA. RADAR
OBS CONFIRM THIS WITH THIN BUT PERSISTENT SHRA BANDS OFF THE VOLUSIA
CO COAST. DEEPER MOISTURE ALSO NOTED OVER MUCH OF THE BAHAMA BANK.
H85-H50 LAPSE RATES BTWN 5.5-6.0C/KM INDICATE SOME DEGREE OF
INSTABILITY...BUT WITH H85-H70 RATES BLO 5.0C/KM..IT WILL BE
DIFFICULT TO INITIALIZE DEEP VERTICAL MOTION.
AS THE RIDGE EXPANDS EWD...LOW/MID LVL WINDS WILL SHIFT MORE TO THE
E...SHUNTING MOISTURE INTO WHAT REMAINS OF THE DRY AIR SLOT.
ALOFT...A MID/UPR LVL RIDGE AXIS OVER THE FL STRAITS WILL PUSH A
BAND OF MID LVL VORTICITY BAND OUT OF S FL AND ACRS LAKE OKEECHOBEE.
A DEPARTING H30-H20 JET STREAK OFF THE CAROLINA COAST WILL CONTINUE
TO DRAG CONSIDERABLE HIGH CLOUDS ACRS THE PENINSULA AS WELL.
DESPITE THE INCREASING MID LVL VORTICITY...OVERALL INSTABILITY WILL
BE LIMITED. THE COMBINED EFFECTS OF THE LINGERING DRY AIR...DENSE
UPR CLOUD DECK LIMITING INSOLATION...AND VERY WEAK H85-H70 LAPSE
RATES WILL BE TOO MUCH TO GENERATE TSRAS. THROW IN THE DEEPENING
ONSHORE FLOW THAT WILL CREATE A DIFFUSE EAST COAST SEA BREEZE WITH
WEAK SFC/LOW LVL FORCING...AND THUNDER CHANCES BECOME TOO LOW TO
MENTION. WILL GO WITH ISOLD COASTAL SHRAS THRU EARLY AFTN...
AREAWIDE THRU EARLY EVNG...THEN BACK TO COASTAL THRU TONIGHT.
ONSHORE FLOW AND CONSIDERABLE UPR LVL CLOUDS WILL KEEP MAX TEMPS
NEAR AVG (M80S)...MIN TEMPS ABV AVG (L70S).
WED-THU...
SURFACE HIGH PRESSURE RIDGE NORTH OF THE AREA WILL PROVIDE AN
EASTERLY WIND FLOW. THE LATEST GFS RUN SHOWS OLD FRONTAL BAND
MOISTURE LIFTING BACK INTO THE AREA WED SO HAVE MAINTAINED CHANCE
POPS (30 PERCENT COAST AND 40 PERCENT INLAND). THE GFS SHOWS AN
UPPER LEVEL SHORTWAVE TROUGH APPROACHING THU SO HAVE GONE WITH 40
POPS AREAWIDE.
FRI-TUE...
UPPER LEVEL SHORTWAVE TROUGH SHOULD SHIFT EAST OF THE AREA ON FRI
AND DECREASE POPS. THE GFS INDICATES LOWER POPS SO HAVE GONE WITH
30 PERCENT AREAWIDE.
WEEKEND-EARLY NEXT WEEK..THE MODELS GENERALLY AGREE ON A MORE
SUBSTANTIAL TROUGH ORGANIZING OVER THE EASTERN PART OF THE
COUNTRY. THERE ARE SOME TIMING AND STRENGTH DIFFERENCES BETWEEN
THE GFS AND ECMWF. THE GFS IS STRONGER...THOUGH THE 00Z ECMWF HAS
TRENDED DEEPER FROM ITS 12Z RUN.
WILL STAY WITH 30-40 POPS THROUGH THE PERIOD...HOWEVER THE SUN-TUE
PERIOD MAY HAVE GREATER CHANCES. WILL WAIT A LITTLE LONGER TO GO
HIGHER THOUGH AS WE DO NOT WANT TO DIFFER TOO MUCH FROM CLIMO THAT
FAR OUT IN THE FORECAST.
&&
.AVIATION...
ALL SITES VFR WITH PREVAILING CIGS AOA FL120 UNLESS OTHERWISE NOTED:
THRU 25/12Z...BRIEF MVFR VSBYS/CIGS IN ISOLD SHRAS N OF KTIX. BTWN
25/12Z-25/24Z...SLGT CHC MVFR SHRAS COASTAL SITES...AFT 25/18Z SLGT
CHC IFR TSRAS INTERIOR SITES...OCNL SFC WND G20KTS COASTAL SITES.
AFT 26/00Z...SLGT CHC MVFR SHRAS COASTAL SITES.
&&
.MARINE...
TODAY-TONIGHT...
HI PRES RIDGE AXIS EXTENDING FROM THE CANADIAN MARITIMES...ACRS THE
NC OUTER BANKS...O THE RIO GRANDE VALLEY WILL GENERATE A GENTLE TO
MODERATE E/NE BREEZE ACRS THE LCL ATLC. EARLY AM OBS FROM THE DATA
BUOYS SHOW THE SWELL THAT HAS BEEN ANTICIPATED FOR THE PAST FEW DAYS
HAS BEGUN IMPACTING THE WATERS WELL OFFSHORE. BOUY010/012 BOTH HAVE
MEASURED +6FT SEAS SINCE MIDNIGHT WITH A 4-5FT SWELL COMPONENT.
BUOY009 STILL HOLDING BTWN 3-4FT...BUT THIS WILL CHANGE NOTICEABLY
BY DAYBREAK AS SWELL TRAIN ADVANCES WESTWARD.
INITIALLY SEAS MAY BUILD UP TO 7FT IN THE GULF STREAM BUT WILL FALL
BACK TO ARND 6FT BY AFTN AS THE LEADING EDGE OF THE SWELL DAMPENS
OUT ON THE E FL COAST. THIS WINDOW IS TOO NARROW TO WARRANT AN SCA
WITH THE MORNING PACKAGE. HOWEVER... A CAUTIONARY STATEMENT FOR THE
OFFSHORE LEG N OF SEBASTIAN INLET IS PRUDENT AS A SLIGHTLY TIGHTER
PGRAD WILL SUPPORT SFC/BNDRY LYR WNDS ARND 15KTS WITH OCNL GUSTS
OVER 20KTS.
WED-THU...
HIGH PRESSURE RIDGE NORTH OF THE WATERS WILL MAINTAIN AN EASTERLY
WIND FLOW. THE LATEST MARINE MOS INDICATES SPEEDS ABOUT 10-13 KNOTS.
HIGHER MOISTURE IS FORECAST TO RETURN SO THE CHANCE FOR
SHOWERS/STORMS WILL BE INCREASING.
FRI-SAT...
THE HIGH PRESSURE RIDGE IS FORECAST TO WEAKEN. THE LATEST GFS
INDICATES WINDS 5-10 KNOTS MOSTLY FROM THE EAST. RAIN CHANCES MIGHT
SLIGHTLY DECREASE FROM THE WED-THU VALUES.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 85 71 87 75 / 20 20 30 20
MCO 86 72 90 73 / 20 10 40 20
MLB 87 73 87 77 / 20 20 30 20
VRB 86 73 88 75 / 20 20 30 20
LEE 87 70 90 73 / 20 10 40 20
SFB 86 72 89 74 / 20 10 40 20
ORL 86 72 90 75 / 20 10 40 20
FPR 86 73 87 75 / 20 20 30 20
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...BRAGAW
LONG TERM/IMPACT WX...LASCODY
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1159 AM EDT TUE SEP 25 2012
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 303 AM EDT TUE SEP 25 2012
A COUPLE OF FRONTS WILL MOVE INTO THE AREA AND LINGER THROUGH THE
END OF THE WORK WEEK...KEEPING CHANCES FOR RAIN ACROSS MUCH OF THE
AREA THROUGH THEN. HIGH PRESSURE WILL THEN BUILD IN AND KEEP MUCH OF
THE WEEKEND INTO EARLY NEXT WEEK DRY. TEMPERATURES WILL RETURN TO
BELOW AVERAGE BY THE WEEKEND.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1159 AM EDT TUE SEP 25 2012
SATELLITE AND RADAR MOSAIC TRENDS SHOW MUCH OF THE AREA CURRENTLY
DRY AND COULD SEE THAT CONTINUE FOR THE NEXT FEW HOURS. HRRR AND
RAP MODELS CONCUR AND SHOW REDEVELOPMENT LATER THIS
AFTERNOON...MAINLY ACROSS THE CENTRAL AND NORTHERN COUNTIES AFTER 21Z.
HOWEVER SATELLITE TRENDS INDICATE POTENTIAL FOR SOME CLEARING IN
THE SOUTH OVER THE NEXT SEVERAL HOURS AND THIS COULD INCREASE
INSTABILITY THERE ENOUGH TO ALLOW FURTHER DEVELOPMENT THERE AS
WELL. WITH THESE THINGS IN MIND HAVE TRENDED POPS DOWN TO CHANCE
CATEGORY THROUGH 21Z...WITH HIGHER CHANCES IN THE NORTH FROM 18 TO
21Z PER THE MODEL TRENDS MENTIONED...AND THEN LIKELY EVERYWHERE
FROM 21 TO 0Z. BASED ON PROGGED INSTABILITY LEFT THUNDER OUT OF
THE NORTH UNTIL AFTER 18Z AND THEN RAMPED UP TO SCATTERED STORMS
EVERYWHERE AFTER 21Z.
ALSO DROPPED HIGH TEMPERATURES A BIT IN THE NORTH WHERE IT IS LESS
LIKELY TO SEE MUCH IN THE WAY OF SUNSHINE.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
ISSUED AT 303 AM EDT TUE SEP 25 2012
FOCUS IS ON CHANCES FOR RAIN THROUGH THE PERIOD. MODELS ARE IN
DECENT AGREEMENT WITH OVERALL PATTERN...ALTHOUGH SOME HAVE
DIFFERENCES IN LOCATION OF FRONT. A BLEND OF MODELS LOOKS BEST GIVEN
UNCERTAINTIES IN FRONTAL PLACEMENT LATER IN THE PERIOD.
WITH THE FRONT IN THE AREA TONIGHT AND FORCING CONTINUING...WENT
LIKELY POPS ALL AREAS AGAIN THIS EVENING. DID LOWER THE POPS SOME IN
THE NORTHWEST AFTER 06Z THOUGH AS THE FRONT SINKS SOUTH. TRENDED
TOWARD MAV MOS FOR LOW TEMPERATURES GIVEN THE CLOUDS AND RAINFALL.
AS THE FRONT SLOWLY SINKS ITS WAY SOUTH THROUGH THE REMAINDER OF THE
SHORT TERM...AND UPPER SUPPORT WEAKENS...GRADUALLY LOWERED POPS FROM
NORTH TO SOUTH AND GRADUALLY THROUGH TIME FOR THE REMAINDER OF THE
SHORT TERM.
FOR TEMPERATURES...STUCK FAIRLY CLOSE TO MAV MOS OR A BLEND OF
MET/MAV THROUGH THE PERIOD.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
ISSUED AT 234 AM EDT TUE SEP 25 2012
THE ONLY PERIOD THAT WILL INCLUDE RAIN CHANCES DURING THIS PERIOD
FOR NOW WILL BE SATURDAY AS A FRONTAL BOUNDARY IS EXPECTED TO BE
SAGGING SOUTHWARD OUT OF THE AREA DURING THE DAY. AS FOR THE REST OF
THE PERIOD...CONFIDENCE REMAINS LOW AS THE ECMWF KEEPS A FRONTAL
BOUNDARY FARTHER SOUTH OVER THE TENNESSEE VALLEY WITH BUILDING HIGH
PRESSURE FROM THE NORTH...WHILE THE GFS IS FARTHER NORTH WITH THE
FRONTAL BOUNDARY AND ALSO DROPS AN UPPER LOW OUT OF THE GREAT LAKES
OVER THE AREA. WITH MOISTURE APPEARING RATHER LIMITED IN EITHER CASE
AND A DRY LOWER LEVEL NORTHEAST FLOW PREVALENT IN BOTH CASES HAVE
TRENDED TOWARD A DRIER FORECAST DURING THIS TIME PERIOD FOR NOW.
&&
.AVIATION /DISCUSSION FOR THE 251500Z TAF UPDATES/...
ISSUED AT 1031 AM EDT TUE SEP 25 2012
TRENDS HAVE BEEN FOR MVFR OR WORSE CEILINGS THROUGH 16Z OR
LATER...SO AT LEAST HAD TO TEMPO LOW CEILINGS FOR ALL THE SITES WITH
HUF THE WORST AT 5K FEET. OTHERWISE...LIGHTNING AND RADAR TRENDS
SUGGEST TEMPO TS GROUPS AT HUF AND BMG WITH ONLY TEMPO -SHRA AT IND
AND LAF THROUGH 16Z-18Z.
PREVIOUS DISCUSSION FOLLOWS...
VFR CIGS ARE EXPECTED TO DETERIORATE TO MVFR DURING MUCH OF THE
PERIOD.
RADAR TRENDS SHOW AN AREA OF SHRA AND TSRA JUST WEST OF INDIANA
PROGRESSING EAST. PROPAGATION SUGGESTS THIS AREA SHOULD REACH OUR
AREA SHORTLY AFTER ISSUANCE TIME...HOWEVER TSRA COVER APPEARS TO
BECOME LESS WIDESPREAD AS THE SYSTEM APPROACHES. ACTIVE WEATHER
PATTERN WILL CONTINUE TODAY. AFTER THIS MORNINGS WAVE
PASSES...ANOTHER S/W LOOKS TO PUSH THROUGH THE AREA DURING THE
EVENING HOURS AS TIME HEIGHTS AGAIN SHOW DEEP SATURATION AND
STRONG LIFT.
AS THAT SYSTEM DEPARTS...LIGHT WINDS AND RECENT RAIN WILL LEAD TO
GOOD CONDITIONS FOR FOG FORMATION WITH MVFR TO IFR CONDITIONS
EXPECTED TOWARD 12Z WED.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...CP
SHORT TERM...50
LONG TERM....PUMA
AVIATION...JP/MK
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
749 AM EDT TUE SEP 25 2012
...Updated Aviation Discussion...
.Forecast Update...
Updated at 635 AM EDT Tue Sep 25 2012
Complex of storms moving into southwest Indiana this morning.
Should cross our southern Indiana and extreme northern Kentucky
counties between 7am to Noon so have updated POPs to 60% for
numerous t-storms. 0.75 inch hail has been reported in eastern
Illinois so will need to watch these storms for small hail as they
move into our counties. Lowered POPs to only 20% over a larger
portion of south central KY for this morning. Only a few radar
echoes (likely virga or a few sprinkles) showing up south of the
main complex. The HRRR has handled convection the best.
&&
.Short Term (Tuesday - Wednesday)...
Issued at 315 AM EDT Tue Sep 25 2012
A complex forecast is in store for the next 24-36 hrs as multiple
upper level disturbances and a nocturnal LLJ spark convective
complexes along a sfc front laid out to our northwest. Have used a
combo of high res model guidance to put some sort of timing to the
waves although this may need to be adjusted given the difficulty in
timing these features.
Early this morning, an upper level wave was diving southeast across
the upper Plains States, and isentropic lift and a LLJ were
increasing from MO/IL and southwest into the lower Plains states/mid
Mississippi River Valley. A warm front was slowly lifting north
over MO/IL as well. A combination of these features was sparking
elevated convection over MO/IL as of 645Z. This convective complex
is expected to continue to develop farther south this morning and
move east mainly impacting our southern Indiana and northern KY
counties between 12-18Z. Lots of virga is noted ahead of the
complex on radar due to dry lower levels. Max QPF amounts look to
be less than a quarter inch north of the Ohio River this morning.
Then most mesoscale models indicate we should see a lull or less
coverage in convection for the early and mid afternoon hours today.
By mid to late afternoon, another storm complex should initiate
along the stalled frontal boundary to our northwest. This complex
of storms will likely move east into southern Indiana and central KY
after 0Z tonight if the 4k NAM is correct. Some of the storms with
this complex could be strong to marginally severe with damaging
winds/large hail the main threats in a narrow window of opportunity
from about 0-3Z tonight. Severity of storms will be dependent on
breaks in the clouds and resultant instability this afternoon
however. South central KY should have the least amount of clouds
and best sfc heating, however, the best mid level flow will be
focused over southern Indiana and northern KY. Thus, this is not an
ideal scenario for severe convection. Will need to monitor cloud
cover/instability this afternoon to get a better handle on storm
strength for this evening. Right now it appears the best location
for strong to severe storms would be over western to west central
KY.
A third round of convection looks likely for Wed although timing and
placement are much less certain than for today. At this point will
broad brush 30-50% POPs over most of the area for Wed afternoon
which looks to be the best time for renewed convection. The LLJ
should be pretty strong Wed morning though so isld-sct waves may
occur Wed morning as well. If convection does not occur Wed
morning/early afternoon and some sfc instability can be achieved, we
may stand a chance at more strong to marginally severe storms Wed
afternoon. Confidence is not great in severe chances...however
forecast soundings look pretty good for winds/hail again if we can
get some instability. The overall wind profile looks better for
Tues night than for Wed afternoon but not by much. Stay tuned for
forecast updates on timing/intensity of storms. Total QPF amounts
from Tues-Wed look to range from 1.5 inches over southern Indiana to
less than a tenth of an inch over south central KY.
As for temperatures, they will be highly dependent on convection and
cloud cover. Will generally assume more clouds over southern
Indiana and northern KY closer to the stalled sfc front. With this
in mind, highs should reach the low 70s over the Bluegrass/southeast
Indiana to low 80s over south central KY near BWG. Lows tonight
should be mild in the lower 60s. Highs Wed should warm into the
upper 70s to mid 80s as we get a little farther into the warm sector.
.Long Term (Wednesday Night - Monday)...
Issued at 321 AM EDT Tue Sep 25 2012
Wednesday Night - Thursday Night...
A frontal boundary will remain draped over the Ohio Valley, slowly
sagging south into central Kentucky through Thursday night. Very
weak zonal flow aloft parallel to the frontal orientation will be
responsible for keeping the boundary in the area, and will continue
mention of scattered showers and thunderstorms through this time
period. At this point, best coverage looks to be Wednesday night and
Thursday across southern Indiana and central Kentucky. Instability
and shear profile looks marginal for severe weather, so overall
threat is low at this time.
Temperatures on Wednesday night should remain mild for this time of
year, generally in the low to mid 60s. The frontal boundary should
be bisecting the CWA from west to east by Thursday afternoon,
resulting in a larger temperature spread from north to south. Look
for highs in the upper 70s north, to lower 80s south. Thursday night
will bring cooler temperatures in the north down to the lower 50s.
South central Kentucky has the best shot at holding on to lower 60s.
Friday - Saturday Night...
By Friday, closed low will begin to slide into the northern Great
Lakes region, with increased northwest flow over the Ohio Valley.
General model consensus takes the frontal boundary to the KY/TN
border in response to the increased westerlies and will buy into
this solution. Have confined the best (scattered) pops across south
central Kentucky. Highs Friday should range from lower 70s north to
upper 70s south. Friday night through Saturday night will bring the
closed low solidly over the Great Lakes region with a fairly strong
consensus (minus Op GFS) in the front and best precipitation chances
in the Tennessee Valley. As the previous forecast alluded to, we may
be void of any noticeable triggering features for precipitation and
therefore pretty dry during this time. Will still mention some
chances especially across the south due to complex upper air pattern
and model uncertainty. Lows Friday and Saturday nights should range
in the low 50s north to upper 50s south. Saturday should again be in
the low to mid 70s across the region.
Sunday - Monday...
Very low confidence in the Sunday/Monday time frame as models
diverge significantly due to the complex upper air pattern. Prefer
to stick with a ECWMF/GEM/GFS ensemble compromise which keeps the
northern cut off low generally over the Great Lakes and southern
stream energy south of us. Cannot rule out one of these features
impacting the area more directly so will mention only small chances
through the end of the forecast period.
&&
.Aviation (Special 13Z TAF Issuance)...
Issued at 748 AM EDT Tue Sep 25 2012
=======================================
13Z Special Update
=======================================
Latest radar imagery shows a convective complex heading generally
eastward at 40kts. Based on this speed, this complex will start to
have induce negative impacts on KSDF within the next hour. These
negative impacts will be short lived as the line moving quickly so a
30-45 minute window of IFR/MVFR conditions due to thunderstorms is
highly likely. Surface winds will continue out of the southeast
ahead of the line and then quickly shift to the west and northwest
after the line passes. Surface winds of VRB15G30KT will be possible.
Previous forecast for KLEX still looks good. Should this line hold
together, it would start inflict negative impacts around KLEX by
25/1430-1500Z.
=======================================
Previous Discussion
=======================================
An upper level disturbance will dive towards the region from the
northwest this morning. At the same time, isentropic lift will
increase along and south of a warm front lifting north to the west
of our region. These features have spurred a convective complex
which looks to impact SDF around 13Z and LEX around 1430Z this
morning with t-storms. MVFR conditions could be realized in these
t-storms and have went ahead with a tempo MVFR group at SDF. LEX
would need to be updated with an MVFR tempo if the complex holds
together and maintains strength. BWG should just see a few showers
if anything this morning. Have used a combo of high res models and
obs to arrive at this soln.
We should see a lull or decrease in showery activity for this
afternoon with models indicating another complex of storms forming
to our west along a stalled frontal boundary by mid to late
afternoon and pushing eastward into the terminals after 0Z tonight.
SDF/LEX will see the best chances of convection for the evening
round of convection. Although no flight restrictions were included
in the TAF period, MVFR conditions will be possible in a moderate to
heavy shower or t-storm.
Winds will stay out of the SSE this morning and then SSW for the
rest of the day turning gusty this afternoon especially during the
anticipated lull in convection with possible breaks in the lower
cloud deck. Late tonight, LLWS will be possible courtesy of a
strong LLJ.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........AMS
Short Term.......AMS
Long Term........BJS
Aviation.........MJ/AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
637 AM EDT TUE SEP 25 2012
.Forecast Update...
Updated at 635 AM EDT Tue Sep 25 2012
Complex of storms moving into southwest Indiana this morning.
Should cross our southern Indiana and extreme northern Kentucky
counties between 7am to Noon so have updated POPs to 60% for
numerous t-storms. 0.75 inch hail has been reported in eastern
Illinois so will need to watch these storms for small hail as they
move into our counties. Lowered POPs to only 20% over a larger
portion of south central KY for this morning. Only a few radar
echoes (likely virga or a few sprinkles) showing up south of the
main complex. The HRRR has handled convection the best.
&&
.Short Term (Tuesday - Wednesday)...
Issued at 315 AM EDT Tue Sep 25 2012
A complex forecast is in store for the next 24-36 hrs as multiple
upper level disturbances and a nocturnal LLJ spark convective
complexes along a sfc front laid out to our northwest. Have used a
combo of high res model guidance to put some sort of timing to the
waves although this may need to be adjusted given the difficulty in
timing these features.
Early this morning, an upper level wave was diving southeast across
the upper Plains States, and isentropic lift and a LLJ were
increasing from MO/IL and southwest into the lower Plains states/mid
Mississippi River Valley. A warm front was slowly lifting north
over MO/IL as well. A combination of these features was sparking
elevated convection over MO/IL as of 645Z. This convective complex
is expected to continue to develop farther south this morning and
move east mainly impacting our southern Indiana and northern KY
counties between 12-18Z. Lots of virga is noted ahead of the
complex on radar due to dry lower levels. Max QPF amounts look to
be less than a quarter inch north of the Ohio River this morning.
Then most mesoscale models indicate we should see a lull or less
coverage in convection for the early and mid afternoon hours today.
By mid to late afternoon, another storm complex should initiate
along the stalled frontal boundary to our northwest. This complex
of storms will likely move east into southern Indiana and central KY
after 0Z tonight if the 4k NAM is correct. Some of the storms with
this complex could be strong to marginally severe with damaging
winds/large hail the main threats in a narrow window of opportunity
from about 0-3Z tonight. Severity of storms will be dependent on
breaks in the clouds and resultant instability this afternoon
however. South central KY should have the least amount of clouds
and best sfc heating, however, the best mid level flow will be
focused over southern Indiana and northern KY. Thus, this is not an
ideal scenario for severe convection. Will need to monitor cloud
cover/instability this afternoon to get a better handle on storm
strength for this evening. Right now it appears the best location
for strong to severe storms would be over western to west central
KY.
A third round of convection looks likely for Wed although timing and
placement are much less certain than for today. At this point will
broad brush 30-50% POPs over most of the area for Wed afternoon
which looks to be the best time for renewed convection. The LLJ
should be pretty strong Wed morning though so isld-sct waves may
occur Wed morning as well. If convection does not occur Wed
morning/early afternoon and some sfc instability can be achieved, we
may stand a chance at more strong to marginally severe storms Wed
afternoon. Confidence is not great in severe chances...however
forecast soundings look pretty good for winds/hail again if we can
get some instability. The overall wind profile looks better for
Tues night than for Wed afternoon but not by much. Stay tuned for
forecast updates on timing/intensity of storms. Total QPF amounts
from Tues-Wed look to range from 1.5 inches over southern Indiana to
less than a tenth of an inch over south central KY.
As for temperatures, they will be highly dependent on convection and
cloud cover. Will generally assume more clouds over southern
Indiana and northern KY closer to the stalled sfc front. With this
in mind, highs should reach the low 70s over the Bluegrass/southeast
Indiana to low 80s over south central KY near BWG. Lows tonight
should be mild in the lower 60s. Highs Wed should warm into the
upper 70s to mid 80s as we get a little farther into the warm sector.
.Long Term (Wednesday Night - Monday)...
Issued at 321 AM EDT Tue Sep 25 2012
Wednesday Night - Thursday Night...
A frontal boundary will remain draped over the Ohio Valley, slowly
sagging south into central Kentucky through Thursday night. Very
weak zonal flow aloft parallel to the frontal orientation will be
responsible for keeping the boundary in the area, and will continue
mention of scattered showers and thunderstorms through this time
period. At this point, best coverage looks to be Wednesday night and
Thursday across southern Indiana and central Kentucky. Instability
and shear profile looks marginal for severe weather, so overall
threat is low at this time.
Temperatures on Wednesday night should remain mild for this time of
year, generally in the low to mid 60s. The frontal boundary should
be bisecting the CWA from west to east by Thursday afternoon,
resulting in a larger temperature spread from north to south. Look
for highs in the upper 70s north, to lower 80s south. Thursday night
will bring cooler temperatures in the north down to the lower 50s.
South central Kentucky has the best shot at holding on to lower 60s.
Friday - Saturday Night...
By Friday, closed low will begin to slide into the northern Great
Lakes region, with increased northwest flow over the Ohio Valley.
General model consensus takes the frontal boundary to the KY/TN
border in response to the increased westerlies and will buy into
this solution. Have confined the best (scattered) pops across south
central Kentucky. Highs Friday should range from lower 70s north to
upper 70s south. Friday night through Saturday night will bring the
closed low solidly over the Great Lakes region with a fairly strong
consensus (minus Op GFS) in the front and best precipitation chances
in the Tennessee Valley. As the previous forecast alluded to, we may
be void of any noticeable triggering features for precipitation and
therefore pretty dry during this time. Will still mention some
chances especially across the south due to complex upper air pattern
and model uncertainty. Lows Friday and Saturday nights should range
in the low 50s north to upper 50s south. Saturday should again be in
the low to mid 70s across the region.
Sunday - Monday...
Very low confidence in the Sunday/Monday time frame as models
diverge significantly due to the complex upper air pattern. Prefer
to stick with a ECWMF/GEM/GFS ensemble compromise which keeps the
northern cut off low generally over the Great Lakes and southern
stream energy south of us. Cannot rule out one of these features
impacting the area more directly so will mention only small chances
through the end of the forecast period.
&&
.Aviation (06Z TAF Issuance)...
Issued at 130 AM EDT Tue Sep 25 2012
An upper level disturbance will dive towards the region from the
northwest this morning. At the same time, isentropic lift will
increase along and south of a warm front lifting north to the west
of our region. These features have already begun to produce virga
over portions of MO/IL and are expected to spur a convective complex
this morning before sunrise over MO/IL/IN. This complex of mostly
showers will push east near the Ohio River just after sunrise. Have
used a combo of high res models to arrive at this soln. The exact
track of the complex is still a little uncertain. For now though,
it appears that light shower activity will move into the terminals
between 13-15Z this morning with SDF/LEX having the better chances
at rain showers. Although a rumble of thunder cannot be ruled out,
it is unlikely so will not include with the morning complex of
convection. We should see a lull or decrease in showery activity
for this afternoon with models indicating another complex of storms
forming to our west along a stalled frontal boundary by mid to late
afternoon and pushing eastward into the terminals after 0Z tonight.
Again, SDF/LEX will see the best chances of convection with better
thunder chances for the evening round of convection. Although no
flight restrictions were included in the TAF period, MVFR conditions
will be possible in a moderate to heavy shower or t-storm.
Winds will stay out of the SSE this morning and then SSW for the
rest of the day turning gusty this afternoon especially during the
anticipated lull in convection with possible breaks in the lower
cloud deck. Late tonight, LLWS will be possible courtesy of a
strong LLJ...will go ahead and include in the SDF TAF.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........AMS
Short Term.......AMS
Long Term........BJS
Aviation.........AMS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
723 AM EDT TUE SEP 25 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 511 AM EDT TUE SEP 25 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS CONTINUE TO SHOW A TROF OVER SE
CANADA INTO THE NE CONUS. REINFORCING SHORTWAVE TROF DROPPED THRU
THE UPPER LAKES LAST EVENING...BRINGING ANOTHER PUSH OF COOLER AIR
INTO THE AREA. AFTER THE SURGE OF WARMER AIR YESTERDAY ON GUSTY W/SW
WINDS AHEAD OF SHORTWAVE...850MB TEMPS ARE BACK DOWN TO 0C ACROSS
LAKE SUPERIOR...BUT ARE STILL AROUND 5C OVER THE FAR SCNTRL FCST
AREA PER LATEST RUC ANALYSIS. RELATIVELY DRY AIR HAS ALSO FOLLOWED
SHORTWAVE INTO UPPER MI...BUT UPSTREAM CWPL SOUNDING AT 00Z SHOWED
NEAR SATURATION FROM ABOUT 900MB TO 700MB. ALTHOUGH RECENT SATELLITE
IMAGERY SHOWS A SLIGHT INCREASE IN LAKE EFFECT CLOUDS...COVERAGE IS
STILL VERY LIMITED. NO SHRA ARE EVIDENT. TO THE N...CANADIAN RADARS
SHOW SOME -SHRA OFF LAKE NIPIGON.
MAIN CONCERN IN THE SHORT TERM WILL MAINLY BE LAKE EFFECT SHRA
POTENTIAL. SHORTWAVE UPSTREAM IN ERN MANITOBA AND FOLLOWING PIECE OF
ENERGY A LITTLE FARTHER N WILL BE ENHANCING FACTORS FOR SHRA
DEVELOPMENT. WITH DEEP LAYER FORCING PER QVECTORS SPREADING OVER THE
AREA TODAY ALONG WITH AN INCREASE IN LOW-LEVEL MOISTURE...EXPECT SOME
-SHRA DEVELOPMENT...BUT THE DISRUPTION OF LAKE EFFECT PROCESSES BY
DAYTIME HEATING WILL BE A SIGNIFICANT NEGATIVE FACTOR. PERIODIC
HEAVY WAVE ACTION ON LAKE SUPERIOR OVER THE LAST WEEK OR SO HAS
RESULTED IN MID LAKE WATER TEMPS FALLING TO 10-13C WHILE READINGS
AROUND 15-16C ARE PROBABLY STILL MORE COMMON OVER THE SRN PORTION OF
THE LAKE. SO OVERWATER INSTABILITY IS A LITTLE MORE MARGINAL...
ESPECIALLY FOR THE MORE DISRUPTIVE DAYTIME HRS. AT THIS POINT...
NOTHING MORE THAN SCHC POPS APPEAR WARRANTED...MAINLY OVER THE
NCNTRL FCST AREA AS DRIER AIR TO THE W SHOULD PREVENT ANY SHRA
DEVELOPMENT OFF WRN LAKE SUPERIOR.
SHRA COVERAGE SHOULD TEND TO INCREASE LATE TONIGHT AS 850MB TEMPS
FALL TOWARD -2C AND A WEAK SFC TROF DROPS S ACROSS THE LAKE IN
ASSOCIATION WITH SHORTWAVE. TIMING OF TROF WILL ALSO COINCIDE WITH
THE MORE FAVORABLE MIN OF THE DIURNAL CYCLE. THUS...HAVE POPS
INCREASING TO CHC OVER THE NCNTRL/NE FCST AREA LATE TONIGHT. LEFT
THE W DRY DUE TO LARGER AREA OF COOLER WATER OVER THE WRN LAKE AND
DUE TO DEEP LAYER QVECTOR DIVERGENCE DOMINATING. SOME OF THE HIGH
RES MODEL GUIDANCE INDICATES -SHRA WILL OCCUR OVER THE W...SO WILL
NEED TO REEXAMINE POTENTIAL AGAIN IN LATER FCSTS. IN THE INTERIOR W
TONIGHT...THERE SHOULD BE A SUFFICIENT LACK OF CLOUDS TO ALLOW TEMPS
TO FALL TO AROUND 30F...RESULTING IN FROST DEVELOPMENT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 511 AM EDT TUE SEP 25 2012
SHORTWAVE WILL BE EXITING THE CWA TO THE SE AT THE START OF THE
PERIOD...SETTING UP A PERIOD OF SPLIT FLOW THROUGH THE END OF THE
WEEK. THE NRN STREAM WILL BE SET IN CANADA...WHILE THE SRN STREAM
WILL BE OVER THE SRN HALF OF THE CONUS. THIS WILL ALLOW FOR HIGH
PRESSURE TO SETTLE IN AND PRODUCE A FAIRLY DRY LONG TERM PERIOD.
FORCING FROM THE SHORTWAVE...COMBINING WITH A POCKET OF LLVL
MOISTURE...SHOULD ALLOW SHOWERS TO BE ONGOING OVER SCNTRL/ERN LAKE
SUPERIOR AND ERN UPPER MI. THESE SHOWERS WILL BE AIDED BY ENHANCED
LLVL CONVERGENCE AND INCREASED LK INSTABILITY WITH H850 TEMPS AROUND
1C. THE SHOWERS SHOULD CONTINUE THROUGH MUCH OF THE MORNING...BUT
HIGH PRESSURE BUILDING IN AND THE QUICKLY EXITING SHORTWAVE/MOISTURE
SHOULD BRING A DIMINISHING TREND IN THE EARLY AFTERNOON.
ANTICYCLONIC FLOW INCREASING THROUGH THE DAY AND DRYING ALOFT
LOWERING THE CAPPING INVERSION WILL ALSO DIMINISH THE SHOWERS. WITH
THE CLOUDS IN PLACE FOR MUCH OF THE DAY...EXPECT HIGHS TO ONLY RISE
INTO THE 50S...WITH THE COOLEST VALUES OVER THE N WHERE THE CLOUD
COVER WILL BE THE THICKEST.
THIS HIGH WILL REMAIN IN PLACE THROUGH AT LEAST THURS NIGHT AND LEAD
TO DRY WX OVER UPPER MI. EXPECT A COLD NIGHT WED NIGHT WITH THE HIGH
BEING NEARLY OVERHEAD. PWATS AROUND 50 PERCENT OF NORMAL AND CLEAR
SKIES WILL PROMOTE RADIATIONAL COOLING AND EXPECT LOWS IN THE UPPER
20S AND LOWER 30S OVER MOST INTERIOR LOCATIONS. THIS WILL PRODUCE
ANOTHER DECENT FROST/FREEZE ACROSS THE AREA. SINCE MOST INTERIOR
LOCATIONS HAVE SEEN A FROST OR FREEZE ALREADY THIS MONTH...OUR
ADVISORY/WARNING HEADLINES HAVE ENDED...BUT WILL CONTINUE TO MENTION
FROST DURING THE TRANSITION PERIOD.
OTHER THAN SOME DIURNAL CU OVER THE SE HALF OF UPPER MI THURS
AFTN...EXPECT MOSTLY CLEAR SKIES TO CONTINUE ON THURS AND INTO FRI.
GRADUALLY WARMING H850 TEMPS WILL LEAD TO HIGHS RISING INTO THE 60S
FOR THURS/FRI...WHICH IS BACK TO NORMAL.
THE GREATEST UNCERTAINTY FOR THE LONG TERM FORECAST COMES WITH THE
SHORTWAVE THAT MOVES THROUGH THE NRN STREAM IN ONTARIO ON FRI. THIS
WILL DRAG A WEAK COLD FRONT ACROSS UPPER MI LATE THURS NIGHT AND
INTO FRI...BUT WILL ONLY CAUSE A SLIGHT WINDSHIFT.
THEN...DETERMINISTIC AND ENSEMBLE MODELS ARE STARTING TO TREND
TOWARDS THE SHORTWAVE BECOMING CLOSED/CUT OFF OVER FAR SE ONTARIO ON
SAT AND SLOWLY DRIFTING SSW INTO THE GREAT LKS. CONFIDENCE IS
INCREASING ON THIS OCCURRENCE...BUT THE LOCATION VARIES DEPENDING
ON THE MODEL. AT THIS POINT...WITH MOISTURE NOT EXPECTED TO BE TOO
FAR FROM THE SHORTWAVE WHILE MOVING THROUGH ONTARIO...DON/T THINK
THERE WILL BE MUCH MOISTURE TO WORK WITH WHEN THE TROUGH CUTS OFF.
THEREFORE...WILL CONTINUE TO FOLLOW A DRY FORECAST FOR THE WEEKEND
AS THE GENERAL CONSENSUS OF THE MODELS HAS THE UPPER LOW CENTERED
OVER LK HURON AND WEAK HIGH PRESSURE OVER THE CWA. RIGHT NOW
TEMPERATURES APPEAR TO BE SEASONABLE FOR THE END OF THE WORK WEEK
AND INTO THE WEEKEND.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 722 AM EDT TUE SEP 25 2012
AN INCREASE IN OVERWATER INSTABILITY AND AN INCREASE IN LOW-LEVEL
MOISTURE FROM THE N SHOULD RESULT IN SCT/BKN STRATOCU DEVELOPING
THIS MORNING. CIGS SHOULD BE VFR AT KIWD/KCMX. AT KSAW...INCLUDED
HIGH MVFR CIGS DUE TO LONGER OVERWATER FETCH AND PRESENCE OF SOME
MVFR CIGS UPSTREAM IN NRN ONTARIO.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 511 AM EDT TUE SEP 25 2012
HIGH PRES/WEAK PRES GRADIENT WILL GENERALLY DOMINATE FOR THE REST OF
THIS WEEK...RESULTING IN WINDS UNDER 20KT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1003 AM CDT TUE SEP 25 2012
.UPDATE...
.DISCUSSION...
UPDATE TO THE FORECAST FOR THE ISOLATED SHOWERS DEVELOPING IN
CONJUNCTION WITH A WEAK UPPER LEVEL DISTURBANCE ACROSS WRN
NEBRASKA. LAPSE RATES ARE STEEP AT KDNR AND KLBF SO WE MIGHT SEE
SOME ISOLATED THUNDER. THE RUC SHOWS NO QPF WHILE THE HRRR IS
PUMPING OUT LOTS OF RADAR RETURNS BUT LITTLE ACCUMULATION.
THINKING IS THAT THE RADAR RETURNS WILL WEAKEN AS THEY ENCOUNTER DRY
AIR FARTHER EAST AND DISSIPATE BEFORE REACHING HIGHWAY 83. WE
WILL SEE LATER THIS MORNING.
&&
.PREV DISCUSSION... /ISSUED 650 AM CDT TUE SEP 25 2012/
AVIATION...
FOR THE KLBF AND KVTN TERMINALS 12Z TAFS.
UPPER LEVEL LOW PRESSURE WILL MOVE INTO THE CENTRAL ROCKIES TODAY.
THIS FEATURE WILL SPREAD ABUNDANT HIGH CLOUDINESS TO WESTERN NEBRASKA
WITH CIGS RANGING FROM 10000 TO 15000 FT AGL. ONLY THIN HIGH
CLOUDINESS AOA 20000 FT IS FORECAST ACROSS NORTHERN NEBRASKA.
WINDS OVER THE NEXT 24 HOURS WILL BE LIGHT AND VARIABLE THROUGH
17Z. THEREAFTER...EXPECT LIGHT EASTERLY WINDS AT UNDER 10 KTS
THROUGH 06Z WEDNESDAY.
PREV DISCUSSION... /ISSUED 415 AM CDT TUE SEP 25 2012/
DISCUSSION...
PRIMARY FORECAST CONCERNS FOR THIS FORECAST CYCLE INCLUDE
PRECIPITATION CHANCES THROUGH SATURDAY AND TEMPERATURES THROUGH
THE SAME TIME PERIOD
WATER VAPOR IMAGERY THIS MORNING SHOWED LONGWAVE TROUGH OVER THE
NORTHEAST QUARTER OF THE COUNTRY...WITH THE UPPER LOW CENTERED
OVER HUDSON BAY. A SECOND LONGWAVE TROUGH WAS SEEN OVER THE
NORTHERN PACIFIC OCEAN...WITH A FAIRLY STRONG SHORTWAVE TROUGH
JUST DOWNSTREAM OF THE PACIFIC TROUGH INTO WESTERN CANADA AND THE
PACIFIC NORTHWEST. RIDGING WAS IN PLACE BETWEEN THESE
SYSTEMS...WHICH EXTENDED INTO NORTH CENTRAL CANADA. THE GENERAL
FLOW IMPACTING THE LOCAL AREAS WAS NORTHWEST FLOW...WHILE PICKING
OUT SEVERAL SHORTWAVE TROUGHS. THE FIRST WAS OVER EASTERN SOUTH
DAKOTA....WHILE A SECOND WAS OVER SOUTHERN SASKATCHEWAN AND
ANOTHER OVER EASTERN MANITOBA. THERE WAS ALSO SOME SOUTHERN STREAM
INFLUENCE AS AN UPPER LEVEL LOW CENTERED OVER THE NEVADA/UTAH
BORDER ATTEMPTED TO HELP SOME WEAK UPPER LEVEL RIDGING TO BUILD
INTO EASTERN COLORADO THIS MORNING. AHEAD OF THE RIDGING WAS A
WEAK MID LEVEL IMPULSE OVER NORTHERN KANSAS WHICH DID HELP THE
DEVELOPMENT OF SOME SHOWERS FROM SOUTHWEST NEBRASKA INTO NORTHERN
KANSAS THIS MORNING. THE NEXT IMPULSE OF ENERGY SEEN WITH THE
UPPER LOW WAS MOVING ACROSS SOUTHERN COLORADO THIS MORNING.
AT THE SURFACE HIGH PRESSURE HAD SETTLED IN OVER NORTHWEST
NEBRASKA...WHICH HAS ALLOWED TEMPERATURES TO DROP SIGNIFICANTLY
WITH READINGS CURRENTLY IN THE LOW 40S. OTHERWISE...A STATIONARY
FRONT WAS SEEN FROM EASTERN WYOMING INTO EASTERN COLORADO...WHILE
ANOTHER COLD FRONT WAS OBSERVED ACROSS SOUTHERN MINNESOTA AND INTO
CENTRAL SOUTH DAKOTA....BEING DRIVEN BY THE SHORTWAVE OVER SOUTH
DAKOTA.
GETTING SOME ECHOES ON RADAR OVER SOUTHERN NEBRASKA THIS MORNING
WITH THE WAVE MOVING SOUTH OF THE AREA THIS MORNING. OBSERVATION
SITES WERE NOT REGISTERING ANY CLOUDS BELOW 10K FEET ONLY A TRACE
OF RAINFALL HAD BEEN REPORTED AT A FEW SITES WITH THESE PASSING
SHOWERS. THIS WOULD CORRELATE WELL WITH THE OBSERVED 25.00Z
SOUNDING FROM LBF WHICH SHOWED VERY DRY AIR BELOW 600MB TO
EVAPORATE AY RAINFALL BEFORE HITTING THE SURFACE.
SHORT TERM...TODAY THROUGH THURSDAY NIGHT
THE ACTIVITY ON RADAR SHOULD DECREASE THIS MORNING AS THE
SHORTWAVE OVER NORTHERN KANSAS PUSHES EAST. DID INCLUDE SPRINKLES
IN THE FORECAST FOR THE SOUTHWEST COUNTIES WITH THESE SHOWERS BUT
THEY SHOULD END BY NOON.
TODAY...THE SHORTWAVE OVER SOUTHERN COLORADO WILL MOVE INTO EASTERN
COLORADO...BUT THEN GETS CAUGHT IN THE SOUTHWEST FLOW WHICH KEEPS
THE MAJORITY OF THE ENERGY ACROSS KANSAS. COULD SEE FURTHER
DEVELOPMENT OF HIGH BASED SHOWERS AND ISOLATED THUNDERSTORMS
ASSOCIATED WITH THIS ENERGY...BUT EXPECT IT TO STAY ACROSS THE FAR
WESTERN PARTS OF THE FORECAST AREA. WITH A GOOD AMOUNT OF MOISTURE
IN THE MID AND HIGH LEVELS ASSOCIATED WITH THE UPPER LOW WILL
CONTINUE TO SEE PARTLY TO MOSTLY CLOUDY SKIES ACROSS THE SOUTHWEST
HALF OF NEBRASKA TODAY. THIS WILL BE THE TREND FOR THE NEXT
SEVERAL DAYS AS WELL...WHILE THE UPPER LOW STAYS OFF TO THE WEST
OF THE FORECAST AREA. TEMPERATURES ALOFT WARM SLIGHTLY FROM
YESTERDAY SO EXPECT HIGHS A FEW DEGREES WARMER TODAY DESPITE THE
CLOUD COVER. THE WARMEST READINGS SHOULD BE OVER NORTH CENTRAL
NEBRASKA WHERE SUNSHINE SHOULD BE PLENTIFUL.
FOR WEDNESDAY...THE MAIN UPPER LOW PROGRESSES EAST INTO COLORADO.
AS SAID ABOVE...MOISTURE WILL CONTINUE TO BE PULLED INTO THE
REGION AHEAD OF THE SYSTEM...BUT MAINLY IN THE MID LEVELS /ABOVE
700MB/. MEANWHILE...DRY HIGH PRESSURE WILL REMAIN IN PLACE OVER
THE UPPER MISSISSIPPI RIVER VALLEY REGION. EASTERLY FLOW WILL
CONTINUE TO PULL DRY AIR INTO NEBRASKA IN THE LOWER LEVELS TO KEEP
THE AIR VERY DRY IN THE BOUNDARY LAYER. ALTHOUGH...SHOWERS MAY
DEVELOP ON WEDNESDAY AS INCREASED LIFT ASSOCIATED WITH THE UPPER
LEVEL LOW MOVES INTO WESTERN NEBRASKA...THE VERY DRY AIR IN THE
BOUNDARY LAYER WILL PROHIBIT THE AREA FROM SEEING A GOOD CHANCE
FOR MEASURABLE RAINFALL. WILL NOT CHANGE MUCH FROM PREVIOUS
FORECAST...KEEPING ONLY A SLIGHT CHANCE FOR MEASURABLE RAIN
WEDNESDAY.
THE CLOSED LOW WILL MIGRATE EAST AND BECOME AN OPEN WAVE THURSDAY
AND THURSDAY NIGHT. THE MAIN CIRCULATION LOOKS TO TRACK ALONG THE
NEBRASKA KANSAS BORDER...WHICH WILL BRING THE HIGHEST CHANCE FOR
RAIN THROUGH THESE PERIODS. IN ADDITION...THE SHORTWAVE TROUGH
CURRENTLY OVER THE PACIFIC NORTHWEST WILL TRACK INTO THE NORTHERN
PLAINS WHICH WILL DRIVE A PACIFIC COLD FRONT TOWARDS THE AREA. IN
ADDITION TO THE RAIN CHANCES WITH THE UPPER LOW...THERE COULD BE
SOME DEVELOPMENT OF THUNDERSTORMS AHEAD OF THIS COLD FRONT WHICH
WOULD MAINLY IMPACT PARTS OF THE PANHANDLE AND WESTERN SANDHILLS.
AGAIN...DRY AIR WILL BE IN PLACE IN THE LOWER LEVELS SO DON/T HAVE
A LOT OF CONFIDENCE ON THE COVERAGE OF ANY RAIN. SO HAVE CONTINUED
THE LOWER CHANCES THROUGH THIS TIME PERIOD.
LONG TERM...FRIDAY THROUGH MONDAY
MODEL SOLUTIONS DIVERGE FURTHER WITH TIME GOING INTO THE WEEKEND.
THE UPPER LEVEL TROUGH OVER THE NORTHERN PLAINS MENTIONED ABOVE
WILL CONTINUE TO HAVE SOME IMPACT ON THE FORECAST AREA THROUGH THE
FIRST PART OF THE WEEKEND. THE MAIN ISSUES WITH HOW THIS
PROGRESSES IS FROM HOW THE UPPER LOW OVER THE GREAT LAKES BEHAVES. THERE
ARE INDICATIONS THAT IT WILL NOT SEE MUCH MOVEMENT /IF THE ECMWF
VERIFIES KEEPING THE UPPER LOW OVER THE GREAT LAKES/FROM THURSDAY
NIGHT THROUGH SATURDAY...KEEPING THE COLD FRONT ACROSS THE HIGH
PLAINS. THIS WOULD LEAD TO POTENTIAL FOR STORMS AND SHOWERS BOTH
FRIDAY AND SATURDAY. ON THE OTHER HAND...IF THE NORTHEAST SYSTEM
IS MORE PROGRESSIVE WHICH WOULD MEAN A DRY FORECAST. WITH LOW
CONFIDENCE...KEPT THE FORECAST DRY THIS CYCLE.
FIRE WEATHER...
SEVERAL DAYS WILL SEE LOW RELATIVE HUMIDITY IN THE
AFTERNOON...HOWEVER WINDS THESE DAYS ARE NOT FORECAST TO BE
PARTICULARLY STRONG. CURRENTLY WEDNESDAY AND THURSDAY LOOK TO SEE
THE STRONGEST WINDS /WITH GUSTS TO 20 MPH/...HOWEVER RELATIVE
HUMIDITY BOTH DAYS SHOULD BOTTOM OUT AROUND 25 PERCENT. AT THIS
POINT DO NOT EXPECT THE NEED FOR ANY FIRE WEATHER HEADLINES IN THE
NEXT WEEK.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...POWER
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1106 AM EDT TUE SEP 25 2012
.SYNOPSIS...
A WARM FRONT WILL APPROACH FROM THE SOUTHWEST TODAY...BECOMING
STATIONARY THROUGH WEDNESDAY. THIS FRONT WILL BE OVERTAKEN BY A
COLD FRONT DROPPING SOUTH FROM THE GREAT LAKES LATE WEDNESDAY AND
THURSDAY. UNSETTLED WEATHER WILL RESULT UNTIL DRIER AIR WORKS IN
FROM THE NORTH LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AREA OF CONVECTION CONTINUES TO WORK E ACROSS THE REGION. IT IS HOLDING
TOGETHER BETTER ACROSS THE KY COUNTIES. THE LATEST HRRR
RUN...WHICH INITIALIZED PRETTY WELL...TAKES THE SRN PORTION OF THE
SYSTEM THRU THE FA. THE NRN HALF APPEARS TO BE WEAKENING AS IT
COMES IN. THE MATCHES WHAT THE HRRR IS FORECASTING.
LATER THIS AFTN...A WRM FNT LIFTING OUT OF MO...WILL COMBINE WITH
A CDFNT DROPPING SOUTHEAST TO CREATE AN AREA OF LIFT ACROSS THE
MIAMI VALLEY. AS THE LIFT DEVELOPS...CONVECTION WILL DEVELOP MAINLY
ALONG AND NORTH OF I-70.
KEPT HIGHS IN THE UPPER 60S ACROSS THE N...WARMING TO THE MID 70S
ACROSS NRN KY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
LOW LEVEL JET WILL INCREASE IN INTENSITY TONIGHT ALONG THE SLOW
MOVING FRONT WHICH WILL ENHANCE THUNDERSTORM DEVELOPMENT AND
STRENGTH. KEPT POPS AS HIGH AS CATEGORICAL. THERE WILL BE A LOW
CHANCE FOR SEVERE THUNDERSTORMS WITH MARGINAL INSTABILITY THE
LIMITING FACTOR IN A REGIME OF VIGOROUS WIND FIELDS.
SHOWERS AND THUNDERSTORMS WILL CONTINUE TO BE LIKELY ON WEDNESDAY
AS THE FRONT MAKES ITS WAY ACROSS THE AREA. THERE MAY BE A BETTER
CHANCE FOR SEVERE THUNDERSTORMS SINCE INSTABILITY WILL BE
INCREASING IN THE PRESENCE OF PERSISTENTLY STRONG WIND FLOW.
RAINFALL TOTALS FOR THIS EVENT WILL PROBABLY EXCEED AN INCH IN
SOME LOCATIONS.
THE FRONT IS EXPECTED TO BE SITUATED NEAR THE OHIO RIVER WEDNESDAY
NIGHT AND THURSDAY. THIS SCENARIO WILL KEEP A GOOD CHANCE FOR
SHOWERS AND THUNDERSTORMS OVER SOUTHERN COUNTIES DURING THAT
TIME FRAME.
HIGH TEMPERATURES WILL BE NEAR NORMAL...MAINLY IN THE 70S.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
THERE IS UNCERTAINTY WHERE A NEARLY STATIONARY FRONT WILL SET UP.
BUT AT THIS POINT IT APPEARS THAT IT WILL BE CLOSE ENOUGH TO THE
SOUTHERN ZONES TO KEEP A CHANCE OF SHOWERS AND POSSIBLY SOME THUNDER
INTO FRIDAY. EXPECT THE BOUNDARY TO FINALLY GET PUSHED FURTHER
SOUTH AS HIGH PRESSURE BUILDS IN ON THE BACK SIDE OF A DEVELOPING
UPPER LOW. THIS SHOULD SPREAD DRIER AIR ACROSS THE REGION FOR THE
WEEKEND INTO MONDAY. TEMPERATURES WILL BE NEAR NORMAL THROUGH THE
PERIOD.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
WESTERLY FLOW ALOFT WITH A MID LEVEL SHORT WAVE TRACKING FROM THE
MID MISSISSIPPI VALLEY EARLY THIS MORNING ACROSS ILN/S FA DURING
THE DAY. AHEAD OF THIS FEATURE MID AND HIGH LEVEL CLOUDS HAVE
INCREASED OVERNIGHT. DUE TO ISENTROPIC LIFT AND ELEVATED INSTBY
ISOLD SHOWERS/THUNDERSTORMS HAVE DEVELOPED ACRS THE NRN MIAMI VLY.
THIS ACTIVITY SHUD WEAKENING BUT CUD PROVIDE A SHOWER TO CENTRAL
OHIO TAF SITES EARLY. BETTER FORCING MOVES IN DURG THE DAY WITH
MARGINAL INSTBY DEVELOPING. SCATTERED SHOWERS AND A FEW
THUNDERSTORMS WILL BECOME MORE WIDESPREAD THROUGH THE LATE
AFTERNOON AND ESPECIALLY INTO TONIGHT. THERE CONTINUES TO BE SOME
MODEL SOLN DIFFERENCES AS TO EXACTLY WHERE THE BEST CHANCE FOR
PCPN WILL LINE UP. IT APPEARS THAT NORTHERN PORTIONS OF OUR FA MAY
HAVE THE BETTER CHANCE DURG THE AFTN AND THEN CHANCES IMPROVE ACRS
ALL TAF SITES THRU THE EVENING. HAVE CONTINUED VFR CIGS WITH
PREVAILING SHOWERS DEVELOPING AND VCTS FOR THUNDER INTO THE
EVENING WITH CIGS AND VSBYS LOWERING INTO MVFR CATEGORY LATE IN
THE TAF PERIOD.
.OUTLOOK...THUNDERSTORMS AND MVFR CONDITIONS POSSIBLE THROUGH
WEDNESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...CONIGLIO
NEAR TERM...SITES
SHORT TERM...CONIGLIO
LONG TERM...
AVIATION...AR
AREA FORECAST DISCUSSION...UPDATED
NWS NASHVILLE TN
1026 AM CDT TUE SEP 25 2012
.UPDATE...
WITH MOST CONVECTIVE ACTIVITY MOVING W TO OUR N ACROSS CNTRL AND NOW
INTO ERN KY...AND PER REGIONAL SATELLITE...RADAR MOSAICS...AND SFC OBS...
BELIEVE THAT WITH QUASI ZONAL FLOW PATTERN ALOFT...THE MID STATE SHOULD
GENERALLY ONLY EXPERIENCE AN INCREASING CLOUDINESS TREND THRU THE REMAINDER
OF THE MORNING HRS W THRU THE EARLY AFTERNOON HRS E...WITH CLRING POSSIBLE
ACROSS THE ENTIRE MID STATE BY THE LATE AFTERNOON HRS. BEST INSTABILITY
SHOULD REMAIN TO OUR N...AND BELIEVE IF ANY RAINFALL DOES OCCUR...AS 12Z
KOHX SOUNDING SHOWS A CONTINUATION OF THE DRY AIRMASS AT THE SFC...ALONG
WITH CURRENT REGIONAL DEWPOINT DEPRESSION TRENDS WELL OVER 5 DEGREES...THAT
RAINFALL WILL BE ISO AT BEST AND MAY NOT EVEN REACH THE GROUND...AND COULD
EVEN BE MOSTLY SPRINKLE IN NATURE. THRU THE REMAINDER OF THE MORNING HRS HAVE
INTRODUCED A SLIGHT CHANCE FOR LOCATIONS GENERALLY W OF I-65 AND FOR THE
AFTERNOON HRS FOR LOCATIONS E OF I-65. IF CLOUDS DO NOT CLEAR THIS LATE
AFTERNOON AS EXPECTED...MIGHT ALSO HAVE TO LOWER HIGH TEMPS...BUT AT THIS
TIME WILL MONITOR FOR POSSIBLE FUTURE UPDATE.
&&
.PREV DISCUSSION.../ISSUED 535 AM CDT TUE SEP 25 2012/
AVIATION 12Z DISCUSSION...
COLD FRONT WILL REMAIN STALLED TO OUR NORTH THROUGH THE TAF PD.
ACTIVE SOUTHERN JET WILL TRANSPORT MOISTURE IN THE FORM OF
MID/HIGH LEVEL CLOUDINESS ACROSS THE TAF AREAS. OTW...VSBYS NOT
EXPECTED TO BE A PROBLEM AS TD DEPRESSIONS TO REMAIN ELEVATED
THROUGH 12Z WED.
PREV DISCUSSION... /ISSUED 436 AM CDT TUE SEP 25 2012/
SHORT TERM...
THE WARM FRONT THAT WILL INFLUENCE WEATHER FOR MOST OF THE WEEK CONTINUES
TO MOVE NORTHEAST THIS MORNING AND IS CURRENTLY STRETCHING ACROSS THE
MID MISSISSIPPI VALLEY AND OHIO VALLEY. A FEW ASSOCIATED SHOWERS HAVE
BEEN MOVING SLOWLY OVER WESTERN KENTUCKY AND WESTERN TN THIS
MORNING. HRRR SHOWS THIS ACTIVITY PERSISTING AND MOVING INTO MIDDLE
TN LATER THIS MORNING. HOWEVER ANY PRECIP SHOULD REMAIN LIGHT AND
MAINLY IMPACT NORTHWESTERN MIDDLE TN. CLOUD COVER WILL INCREASE
TODAY WITH MAINLY HIGH AND MID CLOUDS MOVING IN AS THE FRONT
REMAINS STATIONARY TUESDAY NIGHT AND WEDNESDAY. DIDN`T VENTURE TOO FAR
FROM GUIDANCE AS FAR AS TEMPS GO. HIGHS WILL BE QUITE A BIT WARMER
TODAY THROUGH THURSDAY...AROUND THE MID 80S AS WE SIT IN THE WARM
SECTOR OF THE FRONT. NIGHT TIME LOWS EXPECTED TO BE IN THE LOW 60S
WITH AREAS ALONG THE PLATEAU IN THE UPPER 50S. BEST PRECIP CHANCES
WILL REMAIN NORTH OF THE MIDSTATE BUT KEPT SLIGHT CHANCE POPS IN
THE PICTURE FOR THE NORTHERN COUNTIES FROM WEDNESDAY MORNING
THROUGH THURSDAY NIGHT.
LONG TERM...
MODELS CAN`T SEEM TO AGREE ON THE MOVEMENT OF THE FRONT TO THE
NORTH. THE NAM BRINGS THE FRONT DOWN TOWARD THE NORTHWESTERN
COUNTIES ON THURSDAY WHILE THE GFS KEEPS THE FRONT TO THE NORTH
OF THE MID- STATE UNTIL FRIDAY NIGHT. LEANED TOWARD THE GFS
SOLUTION, WITH CHANCE POPS MAKING AN APPEARANCE FRIDAY MORNING
ALONG THE NORTHERN PORTION OF OUR AREA AND INCREASING IN COVERAGE
AS SATURDAY APPROACHES. MODELS DO AGREE THAT THIS WEEKEND WILL BE
WET AS AN UPPER TROUGH DEEPENS OVER THE SOUTHEAST WITH THE UPPER
LOW MOVING TO THE WEST OF TN. KEPT CHANCE POPS THROUGHOUT THE
WEEKEND. THEN RAIN CHANCES DECREASES FROM WEST TO EAST AS THE MAIN
MOISTURE AXIS MOVES SLIGHTLY EAST MONDAY. WENT SLIGHTLY COOLER
THAN GUIDANCE ON THE TEMPS IN THE LONG TERM.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
31
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
535 AM CDT TUE SEP 25 2012
.AVIATION 12Z DISCUSSION...
COLD FRONT WILL REMAIN STALLED TO OUR NORTH THROUGH THE TAF PD.
ACTIVE SOUTHERN JET WILL TRANSPORT MOISTURE IN THE FORM OF
MID/HIGH LEVEL CLOUDINESS ACROSS THE TAF AREAS. OTW...VSBYS NOT
EXPECTED TO BE A PROBLEM AS TD DEPRESSIONS TO REMAIN ELEVATED
THROUGH 12Z WED.
&&
.PREV DISCUSSION... /ISSUED 436 AM CDT TUE SEP 25 2012/
SHORT TERM...
THE WARM FRONT THAT WILL INFLUENCE WEATHER FOR MOST OF THE WEEK CONTINUES
TO MOVE NORTHEAST THIS MORNING AND IS CURRENTLY STRETCHING ACROSS THE
MID MISSISSIPPI VALLEY AND OHIO VALLEY. A FEW ASSOCIATED SHOWERS HAVE
BEEN MOVING SLOWLY OVER WESTERN KENTUCKY AND WESTERN TN THIS
MORNING. HRRR SHOWS THIS ACTIVITY PERSISTING AND MOVING INTO MIDDLE
TN LATER THIS MORNING. HOWEVER ANY PRECIP SHOULD REMAIN LIGHT AND
MAINLY IMPACT NORTHWESTERN MIDDLE TN. CLOUD COVER WILL INCREASE
TODAY WITH MAINLY HIGH AND MID CLOUDS MOVING IN AS THE FRONT
REMAINS STATIONARY TUESDAY NIGHT AND WEDNESDAY. DIDN`T VENTURE TOO FAR
FROM GUIDANCE AS FAR AS TEMPS GO. HIGHS WILL BE QUITE A BIT WARMER
TODAY THROUGH THURSDAY...AROUND THE MID 80S AS WE SIT IN THE WARM
SECTOR OF THE FRONT. NIGHT TIME LOWS EXPECTED TO BE IN THE LOW 60S
WITH AREAS ALONG THE PLATEAU IN THE UPPER 50S. BEST PRECIP CHANCES
WILL REMAIN NORTH OF THE MIDSTATE BUT KEPT SLIGHT CHANCE POPS IN
THE PICTURE FOR THE NORTHERN COUNTIES FROM WEDNESDAY MORNING
THROUGH THURSDAY NIGHT.
LONG TERM...
MODELS CAN`T SEEM TO AGREE ON THE MOVEMENT OF THE FRONT TO THE
NORTH. THE NAM BRINGS THE FRONT DOWN TOWARD THE NORTHWESTERN
COUNTIES ON THURSDAY WHILE THE GFS KEEPS THE FRONT TO THE NORTH
OF THE MID- STATE UNTIL FRIDAY NIGHT. LEANED TOWARD THE GFS
SOLUTION, WITH CHANCE POPS MAKING AN APPEARANCE FRIDAY MORNING
ALONG THE NORTHERN PORTION OF OUR AREA AND INCREASING IN COVERAGE
AS SATURDAY APPROACHES. MODELS DO AGREE THAT THIS WEEKEND WILL BE
WET AS AN UPPER TROUGH DEEPENS OVER THE SOUTHEAST WITH THE UPPER
LOW MOVING TO THE WEST OF TN. KEPT CHANCE POPS THROUGHOUT THE
WEEKEND. THEN RAIN CHANCES DECREASES FROM WEST TO EAST AS THE MAIN
MOISTURE AXIS MOVES SLIGHTLY EAST MONDAY. WENT SLIGHTLY COOLER
THAN GUIDANCE ON THE TEMPS IN THE LONG TERM.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
21
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1232 PM MDT TUE SEP 25 2012
.UPDATE...BACKED OFF THE SHOWER POTENTIAL ALONG THE FRONT RANGE
TO A SLIGHT CHANCE THROUGH 21Z...THEN A CHANCE THE REST OF THE
AFTERNOON. WEAK ECHOES HAVE BEEN SLOWLY DEVELOPING ALONG THE FRONT
RANGE EARLY THIS AFTERNOON...AND THIS GRADUAL INCREASING TREND
SHOULD CONTINUE THROUGH THE REST OF THE DAY.
&&
.PREV DISCUSSION... /ISSUED 919 AM MDT TUE SEP 25 2012/
UPDATE...NO BIG CHANGES AT THIS TIME. PCPN MAY BE A BIT SLOER TO
DEVELOP THIS AFTERNOON...BUT NOT ENOUGH TO REFLECT ANY MAJOR
ADJUSTMENTS TO THE FORECAST AT THIS TIME. HRRR BRINGS AN INITIAL
BAND OF PCPN ACROSS SW TO NE ACROSS THE CWFA AFTER 18Z BUT THIS
MAY BE OVERDONE. NEXT BAND PROGGED TO MOVE ACROSS LATE THIS AFTN
AND EVENING.
&&
.AVIATION...DO NOT ANTICIPATE ANY MAJOR CHANGES IN THE UPCOMING
TAFS. MAY NEED TO ADJUST THE TIMING OF THE PCPN THIS AFTN AND
EVENING. ONLY ISSUE MAY INVOLVE THE INCLUSION OF VCTS THIS AFTN.
CAPES THIS AFTN ONLY IN THE 400-500 J/KG RANGE...SO MAY OPT TO GO
WITH JUST RAIN SHOWERS...AND DROP THE MENTION OF VCTS. WEAK SFC
WINDS SHOULD TRANSITION TO ENELY THIS AFTN...SO NO CHANGES THERE.
.PREV DISCUSSION... /ISSUED 312 AM TUE SEP 25 2012/
SHORT TERM...AN UPER LEVEL LOW OVER UTAH WILL MOVE SLOWLY EASTWARD
INTO WRN CO BY THIS EVENING AND THEN REMAIN NEARLY STATIONARY
OVERNIGHT. ALTHOUGH THERE WILL BE ABUNDANT MOISTURE QG FIELDS ARE
WK THRU TONIGHT WITH SOME MINOR UPPER LEVEL DIVERGENCE. AT THIS
TIME WILL KEEP HIGHEST POPS IN THE MTNS AND HIGHER FOOTHILLS WITH
CHC POPS ESLEWHERE. TEMPS WILL BE COLD ENOUGH FOR SOME SNOW OVER
THE HIGHEST PEAKS. ACROSS NERN CO AFTN CAPES ARE FCST TO BE 500
J/KG OR LESS THIS AFTN SO AIRMASS IS ONLY MARGINALLY UNSTABLE WHICH
WILL LIMIT INTENSITY OF TSTMS. AS FOR HIGHS WILL KEEP READINGS IN
THE 70S ACROSS NERN CO WITH THE WARMEST READINGS OVER THE FAR NERN
PLAINS.
FOR TONIGHT AS MENTIONED ABV THE WEAK UPPER LEVEL LOW WILL REMAIN
OVER WRN CO. WILL CONTINUE TO SEE SHOWER ACTIVITY IN THE MTNS
THROUGH MIDNIGHT WITH DECREASIGN ACTIVITY THEREAFTER. OVER THE
PLAINS WILL SEE SCT SHOWERS AND A FEW TSTMS IN THE EARLY EVENING
HOURS WHICH SHOULD GRADUALLY END BY MIDNIGHT.
LONG TERM...MODELS SHOW A WEAKENING UPPER CLOSED LOW/UPPER TROUGH
OVER WESTERN AND NORTHERN COLORADO WEDNESDAY THROUGH THURSDAY. IT
MOVES LITTLE...WITH PRETTY WEAK FLOW ALOFT FOR THE CWA THROUGH
THURSDAY NIGHT. THE SYNOPTIC SCALE ENERGY ACCORDING TO THE QG
VERTICAL VELOCITY FIELDS IS VERY WEAK THROUGH THE PERIODS...UPWARD
INTO THURSDAY MORNING...THEN DOWNWARD. THE BOUNDARY LAYER FLOW HAS
A GENERAL WEAK EASTERLY COMPONENT TO IT ALL FOUR PERIODS. IT IS
MAINLY EAST TO SOUTHEAST OVER THE PLAINS. FOR MOISTURE...BOTH THE
GFS AND NAM SHOW QUITE A BIT WEDNESDAY AND WEDNESDAY NIGHT. THE NAM
CONTINUES THIS TREND INTO THURSDAY...WITH A BIT OF DRYING THURSDAY
NIGHT. THE GFS IS DRIER THAN THE NAM ON THURSDAY AND THURSDAY
NIGHT...BUT THERE IS STILL MOISTURE AROUND. QUITE A BIT MORE THAN
WE HAVE SEEN THE LAST MANY DAYS. PRECIPITABLE WATER VALUES ARE IN
THE 0.60 TO 0.85 INCH RANGE ALL FOUR PERIODS...NOT BAD FOR LATE
SEPTEMBER. THE MODELS HAVE CAPE AROUND BOTH WEDNESDAY AND THURSDAY
..MORE SO ON THE NAM...AND BETTER ON BOTH MODELS FOR THE PLAINS.
THE QPF FIELDS HAVE MEASURABLE PRECIPITATION OVER THE CWA WEDNESDAY
THROUGH THURSDAY NIGHT...THE GFS HAS THE MOST...OF COURSE. THERE IS
GENERALLY MORE PROGGED WEDNESDAY AFTERNOON AND NIGHT. CURRENT GFE
GRIDS HAVE PRETTY DECENT POPS GOING ON WEDNESDAY AND WEDNESDAY NIGHT
..WILL CHANGE LITTLE THERE. MAY UP THURSDAY`S POPS A BIT...
ESPECIALLY ON THE PLAINS DURING THE AFTERNOON AND EVENING. FOR
TEMPERATURES...WEDNESDAY`S HIGHS ARE 2-3 C COOLER THAN TODAY`S.
THURSDAY HIGH`S ARE 0-1 C WARMER THAN WEDNESDAY`S. FOR THE LATER
DAYS...FRIDAY THROUGH MONDAY...MODELS HAVE WEAK FLOW ALOFT FRIDAY
AND SATURDAY. BY SUNDAY AND MONDAY...UPPER RIDGE TO THE WEST AND
NORTH BRINGS NORTHERLY AND NORTHEASTERLY FLOW ALOFT TO THE CWA.
THERE WILL BE SOME MOISTURE AVAILABLE FRIDAY AND SATURDAY...BUT
SUNDAY AND MONDAY DRY OUT. TEMPERATURES LOOK TO BE AROUND SEASONAL
NORMALS.
AVIATION...WILL HAVE QUITE A BIT OF MID LVL CLOUD COVER THROUGH
TONIGHT WITH CEILINGS AROUND 10000 FT. OVERALL INSTABILITY THIS
AFTN INTO THE EARLY EVENING IS NOT THAT GREAT SO WILL JUST MENTION
VCTS AND HAVE A PROB GROUP FOR SHOWERS. CEILINGS AND VISBILITIES
SHOULD STAY ABV MVFR WITH ANY PCPN. WINDS EARLY THIS MORNING ARE
WLY AND ARE FCST TO BECOME LIGHT ENE BY 18Z. FOR TONIGHT WINDS WILL
BECOME MORE WSW BY EARLY EVENING. AT THIS TIME DO NOT EXPECT ANY
STRATUS FOR WED MORNING.
HYDROLOGY...THERE WILL BE A GOOD CHANCE OF SHOWERS AND A FEW
AFTERNOON THUNDERSTORMS HOWEVER RAINFALL RATES SHOULD BE UNDER ONE
QUARTER INCH PER HOUR SO THE THREAT OF FLASH FLOODING SHOULD BE LOW
IN THE BURN AREAS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...COOPER
LONG TERM....RJK
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
141 PM EDT TUE SEP 25 2012
.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 303 AM EDT TUE SEP 25 2012
A COUPLE OF FRONTS WILL MOVE INTO THE AREA AND LINGER THROUGH THE
END OF THE WORK WEEK...KEEPING CHANCES FOR RAIN ACROSS MUCH OF THE
AREA THROUGH THEN. HIGH PRESSURE WILL THEN BUILD IN AND KEEP MUCH OF
THE WEEKEND INTO EARLY NEXT WEEK DRY. TEMPERATURES WILL RETURN TO
BELOW AVERAGE BY THE WEEKEND.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1159 AM EDT TUE SEP 25 2012
SATELLITE AND RADAR MOSAIC TRENDS SHOW MUCH OF THE AREA CURRENTLY
DRY AND COULD SEE THAT CONTINUE FOR THE NEXT FEW HOURS. HRRR AND
RAP MODELS CONCUR AND SHOW REDEVELOPMENT LATER THIS
AFTERNOON...MAINLY ACROSS THE CENTRAL AND NORTHERN COUNTIES AFTER
21Z. HOWEVER SATELLITE TRENDS INDICATE POTENTIAL FOR SOME CLEARING IN
THE SOUTH OVER THE NEXT SEVERAL HOURS AND THIS COULD INCREASE
INSTABILITY THERE ENOUGH TO ALLOW FURTHER DEVELOPMENT THERE AS WELL.
WITH THESE THINGS IN MIND HAVE TRENDED POPS DOWN TO CHANCE CATEGORY
THROUGH 21Z...WITH HIGHER CHANCES IN THE NORTH FROM 18 TO 21Z PER
THE MODEL TRENDS MENTIONED...AND THEN LIKELY EVERYWHERE FROM 21 TO
0Z. BASED ON PROGGED INSTABILITY LEFT THUNDER OUT OF THE NORTH UNTIL
AFTER 18Z AND THEN RAMPED UP TO SCATTERED STORMS EVERYWHERE AFTER
21Z.
ALSO DROPPED HIGH TEMPERATURES A BIT IN THE NORTH WHERE IT IS LESS
LIKELY TO SEE MUCH IN THE WAY OF SUNSHINE.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
ISSUED AT 303 AM EDT TUE SEP 25 2012
FOCUS IS ON CHANCES FOR RAIN THROUGH THE PERIOD. MODELS ARE IN
DECENT AGREEMENT WITH OVERALL PATTERN...ALTHOUGH SOME HAVE
DIFFERENCES IN LOCATION OF FRONT. A BLEND OF MODELS LOOKS BEST GIVEN
UNCERTAINTIES IN FRONTAL PLACEMENT LATER IN THE PERIOD.
WITH THE FRONT IN THE AREA TONIGHT AND FORCING CONTINUING...WENT
LIKELY POPS ALL AREAS AGAIN THIS EVENING. DID LOWER THE POPS SOME IN
THE NORTHWEST AFTER 06Z THOUGH AS THE FRONT SINKS SOUTH. TRENDED
TOWARD MAV MOS FOR LOW TEMPERATURES GIVEN THE CLOUDS AND RAINFALL.
AS THE FRONT SLOWLY SINKS ITS WAY SOUTH THROUGH THE REMAINDER OF THE
SHORT TERM...AND UPPER SUPPORT WEAKENS...GRADUALLY LOWERED POPS FROM
NORTH TO SOUTH AND GRADUALLY THROUGH TIME FOR THE REMAINDER OF THE
SHORT TERM.
FOR TEMPERATURES...STUCK FAIRLY CLOSE TO MAV MOS OR A BLEND OF
MET/MAV THROUGH THE PERIOD.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
ISSUED AT 141 PM EDT TUE SEP 25 2012
THE MAIN FOCUS TO THE EXTENDED WILL BE WHETHER OR NOT TO KEEP LOW
POPS ACROSS THE SOUTH FRIDAY NIGHT AND SATURDAY PER THE CENTRAL
REGION INITIALIZATION. LONG RANGE MODELS ARE IN GOOD AGREEMENT ON A
DRY FORECAST FOR THE REMAINDER OF THE EXTENDED AS A BROAD AREA OF
SURFACE HIGH PRESSURE SETS UP ACROSS THE OHIO VALLEY WITH A LOW
PRESSURE SYSTEM WELL TO THE SOUTH ACROSS THE SOUTHERN STATES AND AN
UPPER LOW NEAR THE SAINT LAWRENCE VALLEY.
WITH THE LONG RANGE MODELS STILL SHOWING A GOOD DEGREE OF MODEL TO
MODEL AND MODEL VERSUS MODEL UNCERTAINTY...WILL ACCEPT THE SMALL
POPS FROM CR INIT FRIDAY NIGHT ACROSS THE WHOLE FORECAST AREA AND
SATURDAY ACROSS JUST OUR FAR SOUTH. WILL ALSO ACCEPT THE SLIGHTLY
BELOW NORMAL TEMPERATURES.
&&
.AVIATION /DISCUSSION FOR THE 251800Z TAF ISSUANCE/...
ISSUED AT 1250 PM EDT TUE SEP 25 2012
IFR AND WORSE CEILINGS HAVE BEEN HOLDING SWAY ACROSS THE TERMINALS
EARLY THIS AFTERNOON...HOWEVER EXPECT CEILINGS TO AT LEAST COME UP
TO MVFR AS SATELLITE WAS SUGGESTING A FEW BREAKS ARE POSSIBLE IN THE
OVERCAST. RADAR SUGGESTS ONLY VCSH THROUGH 20Z. AFTER
20Z...ATMOSPHERE SHOULD BECOME UNSTABLE WITH THE BREAKS IN THE
OVERCAST. WARM AIR ADVECTION WILL CONTINUE TO THE NORTH OF A WARM
FRONT ACROSS WESTERN KENTUCKY AND SOUTH OF A COLD FRONT FROM
SOUTHWESTERN WISCONSIN TO NORTHERN IOWA AND NEBRASKA. IN
ADDITION...MORE UPPER WAVES WILL MOVE THROUGH THE ZONAL FLOW ALOFT.
THUS...EXPECT THE SHOWER AND POSSIBLY THUNDERSTORM ACTIVITY TO PICK
UP AGAIN AND CONTINUE TO BE A THREAT THROUGH THE TAF PERIOD. SOUTH
WINDS AROUND 10 KNOTS THIS AFTERNOON WILL BECOME SOUTHWEST
OVERNIGHT.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...CP
SHORT TERM...50
LONG TERM....MK
AVIATION...MK
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1250 PM EDT TUE SEP 25 2012
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 303 AM EDT TUE SEP 25 2012
A COUPLE OF FRONTS WILL MOVE INTO THE AREA AND LINGER THROUGH THE
END OF THE WORK WEEK...KEEPING CHANCES FOR RAIN ACROSS MUCH OF THE
AREA THROUGH THEN. HIGH PRESSURE WILL THEN BUILD IN AND KEEP MUCH OF
THE WEEKEND INTO EARLY NEXT WEEK DRY. TEMPERATURES WILL RETURN TO
BELOW AVERAGE BY THE WEEKEND.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1159 AM EDT TUE SEP 25 2012
SATELLITE AND RADAR MOSAIC TRENDS SHOW MUCH OF THE AREA CURRENTLY
DRY AND COULD SEE THAT CONTINUE FOR THE NEXT FEW HOURS. HRRR AND
RAP MODELS CONCUR AND SHOW REDEVELOPMENT LATER THIS
AFTERNOON...MAINLY ACROSS THE CENTRAL AND NORTHERN COUNTIES AFTER
21Z. HOWEVER SATELLITE TRENDS INDICATE POTENTIAL FOR SOME CLEARING IN
THE SOUTH OVER THE NEXT SEVERAL HOURS AND THIS COULD INCREASE
INSTABILITY THERE ENOUGH TO ALLOW FURTHER DEVELOPMENT THERE AS WELL.
WITH THESE THINGS IN MIND HAVE TRENDED POPS DOWN TO CHANCE CATEGORY
THROUGH 21Z...WITH HIGHER CHANCES IN THE NORTH FROM 18 TO 21Z PER
THE MODEL TRENDS MENTIONED...AND THEN LIKELY EVERYWHERE FROM 21 TO
0Z. BASED ON PROGGED INSTABILITY LEFT THUNDER OUT OF THE NORTH UNTIL
AFTER 18Z AND THEN RAMPED UP TO SCATTERED STORMS EVERYWHERE AFTER
21Z.
ALSO DROPPED HIGH TEMPERATURES A BIT IN THE NORTH WHERE IT IS LESS
LIKELY TO SEE MUCH IN THE WAY OF SUNSHINE.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
ISSUED AT 303 AM EDT TUE SEP 25 2012
FOCUS IS ON CHANCES FOR RAIN THROUGH THE PERIOD. MODELS ARE IN
DECENT AGREEMENT WITH OVERALL PATTERN...ALTHOUGH SOME HAVE
DIFFERENCES IN LOCATION OF FRONT. A BLEND OF MODELS LOOKS BEST GIVEN
UNCERTAINTIES IN FRONTAL PLACEMENT LATER IN THE PERIOD.
WITH THE FRONT IN THE AREA TONIGHT AND FORCING CONTINUING...WENT
LIKELY POPS ALL AREAS AGAIN THIS EVENING. DID LOWER THE POPS SOME IN
THE NORTHWEST AFTER 06Z THOUGH AS THE FRONT SINKS SOUTH. TRENDED
TOWARD MAV MOS FOR LOW TEMPERATURES GIVEN THE CLOUDS AND RAINFALL.
AS THE FRONT SLOWLY SINKS ITS WAY SOUTH THROUGH THE REMAINDER OF THE
SHORT TERM...AND UPPER SUPPORT WEAKENS...GRADUALLY LOWERED POPS FROM
NORTH TO SOUTH AND GRADUALLY THROUGH TIME FOR THE REMAINDER OF THE
SHORT TERM.
FOR TEMPERATURES...STUCK FAIRLY CLOSE TO MAV MOS OR A BLEND OF
MET/MAV THROUGH THE PERIOD.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
ISSUED AT 234 AM EDT TUE SEP 25 2012
THE ONLY PERIOD THAT WILL INCLUDE RAIN CHANCES DURING THIS PERIOD
FOR NOW WILL BE SATURDAY AS A FRONTAL BOUNDARY IS EXPECTED TO BE
SAGGING SOUTHWARD OUT OF THE AREA DURING THE DAY. AS FOR THE REST OF
THE PERIOD...CONFIDENCE REMAINS LOW AS THE ECMWF KEEPS A FRONTAL
BOUNDARY FARTHER SOUTH OVER THE TENNESSEE VALLEY WITH BUILDING HIGH
PRESSURE FROM THE NORTH...WHILE THE GFS IS FARTHER NORTH WITH THE
FRONTAL BOUNDARY AND ALSO DROPS AN UPPER LOW OUT OF THE GREAT LAKES
OVER THE AREA. WITH MOISTURE APPEARING RATHER LIMITED IN EITHER CASE
AND A DRY LOWER LEVEL NORTHEAST FLOW PREVALENT IN BOTH CASES HAVE
TRENDED TOWARD A DRIER FORECAST DURING THIS TIME PERIOD FOR NOW.
&&
.AVIATION /DISCUSSION FOR THE 251800Z TAF ISSUANCE/...
ISSUED AT 1250 PM EDT TUE SEP 25 2012
IFR AND WORSE CEILINGS HAVE BEEN HOLDING SWAY ACROSS THE TERMINALS
EARLY THIS AFTERNOON...HOWEVER EXPECT CEILINGS TO AT LEAST COME UP
TO MVFR AS SATELLITE WAS SUGGESTING A FEW BREAKS ARE POSSIBLE IN THE
OVERCAST. RADAR SUGGESTS ONLY VCSH THROUGH 20Z. AFTER
20Z...ATMOSPHERE SHOULD BECOME UNSTABLE WITH THE BREAKS IN THE
OVERCAST. WARM AIR ADVECTION WILL CONTINUE TO THE NORTH OF A WARM
FRONT ACROSS WESTERN KENTUCKY AND SOUTH OF A COLD FRONT FROM
SOUTHWESTERN WISCONSIN TO NORTHERN IOWA AND NEBRASKA. IN
ADDITION...MORE UPPER WAVES WILL MOVE THROUGH THE ZONAL FLOW ALOFT.
THUS...EXPECT THE SHOWER AND POSSIBLY THUNDERSTORM ACTIVITY TO PICK
UP AGAIN AND CONTINUE TO BE A THREAT THROUGH THE TAF PERIOD. SOUTH
WINDS AROUND 10 KNOTS THIS AFTERNOON WILL BECOME SOUTHWEST
OVERNIGHT.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...CP
SHORT TERM...50
LONG TERM....PUMA
AVIATION...MK
AREA FORECAST DISCUSSION
NWS TOPEKA KS
305 PM CDT TUE SEP 25 2012
.DISCUSSION...
SHORT TERM - THROUGH WEDNESDAY...
SURFACE ANALYSIS AT 18Z INDICATED THAT A RATHER WELL DEFINED SURFACE
LOW OVER FAR SOUTH CENTRAL KANSAS AND NORTH CENTRAL OKLAHOMA...NEAR
THE BORDER OF THE TWO STATES. A SURFACE BOUNDARY...WHICH IS A
REMNANT OF THE BOUNDARY WHICH CAUSED OVERNIGHT SHOWERS IN EASTERN
KANSAS AND WESTERN MISSOURI...IS CURRENTLY LOCATED GENERALLY ACROSS
SOUTHEASTERN KANSAS AND MORE SPECIFICALLY ALONG A LINE ROUGHLY FROM
GARNETT KS TO WELLINGTON KS. THIS BOUNDARY WILL LIKELY BE THE FOCUS
FOR SHOWERS AND THUNDERSTORMS LATER THIS AFTERNOON INTO THIS
EVENING. CURRENT SURFACE WINDS NORTH AND WEST OF THE BOUNDARY ARE
OUT OF THE E-NE...WHILE WINDS TO THE SOUTH AND EAST OF THE BOUNDARY
ARE MORE FROM THE SW. THESE PARALLEL AND OPPOSING WINDS ARE NOT
CREATING ENOUGH CONVERGENCE AT THE MOMENT TO GET LOW LEVEL UPWARD
MOTION. HOWEVER AS THE LOW SLIDES EASTWARD SURFACE WINDS MAY BACK A
LITTLE IN RESPONSE TO THE LOWS MOVEMENT. MODEL FORECAST SOUNDINGS
FOR SOUTHEAST KANSAS INDICATE THAT A STOUT LOW/MID LEVEL WARM NOSE
WILL REMAIN ESTABLISHED THROUGH ABOUT 22Z. AT THAT TIME CONVECTION
MAY OCCUR ALONG AND NEAR THAT BOUNDARY. FURTHER ENHANCING CONVECTION
POTENTIAL IS DECENT 850 MB CONVERGENCE AS SW 850 MB WINDS AT 20 TO
30 KTS NOSE INTO SLIGHTLY SLOWER 850 MB WINDS ACROSS EAST CENTRAL
KANSAS. MID/UPPER SUPPORT FOR ASCENT SHOULD COME LATER ON TONIGHT AS
A QUICKLY MOVING SHORTWAVE TROUGH CRUISES THROUGH THE AREA. THE
COMBINATION OF THE AFOREMENTIONED FACTORS SHOULD LEAD TO SCATTERED
CONVECTION ACROSS PARTS OF EAST CENTRAL AND SOUTHEAST KANSAS. AS
SURFACE WINDS BECOME MORE BACKED THE BOUNDARY MAY ALSO SHIFT
NORTHWARD...CAUSING AREAS ALONG AND SOUTH OF THE KANSAS TURNPIKE TO
HAVE A CHANCE FOR SOME SHOWERS AND THUNDERSTORMS. RAP MESOANALYSIS
AT 18Z SHOWS THAT AROUND 2500 J/KG OF MLCAPE EXISTS ALONG AND SOUTH
OF THAT BOUNDARY INDICATING THAT ANY UPDRAFT THAT IS ABLE TO GET
GOING WILL HAVE QUITE A BIT OF INSTABILITY TO WORK WITH. UPDRAFTS
WILL ALSO HAVE AROUND 20 KTS OF DEEP SHEAR TO WORK WITH...SO SOME
UPDRAFT PERSISTENCE WILL BE POSSIBLE. THE STRONGER CONVECTIVE CELLS
WILL HAVE THE CAPABILITY TO POTENTIALLY PRODUCE SOME LARGE
HAIL...PERHAPS UP TO QUARTER SIZED. CLOUD BASES MAY BE IN THE 5 KFT
TO 6 KFT RANGE WITH GOOD LOW LEVEL LAPSE RATES AND DRY AIR BELOW THE
CLOUD LAYER...SO STRONG GUSTY WINDS WILL ALSO BE POSSIBLE WITH THE
STRONGEST UPDRAFTS. ALTHOUGH A FEW STORMS ARE EXPECTED TO BE STRONG
THIS AFTERNOON WIDESPREAD SEVERE WEATHER IS NOT EXPECTED...WITH THE
MAIN THREAT AREA EXPECTED TO BE ALONG AND SOUTH OF THE KANSAS
TURNPIKE.
WITH THE BOUNDARY REMAINING NEAR THE FORECAST AREA THROUGH THE NIGHT
PERIODS OF MODERATE TO HEAVY RAIN WILL BE POSSIBLE ACROSS AREAS OF
EAST CENTRAL AND SOUTHEASTERN KANSAS. A FEW SHOWERS WILL ALSO BE
POSSIBLE ON WEDNESDAY AS A CONTINUATION OF TUESDAY NIGHTS SHOWERS
AND THUNDERSTORMS. EXPECT THERE TO BE A RATHER TIGHT GRADIENT
BETWEEN THE HIGHER END POPS SOUTH OF INTERSTATE 70 AND AREAS TO THE
NORTH NEAR THE KS/NE BORDER...WITH THE HIGHEST POPS REMAINING IN
EAST CENTRAL AND SOUTHEAST KANSAS.
JL
MID TERM - WEDNESDAY NIGHT THROUGH FRIDAY NIGHT...
THE UNSETTLED WEATHER PATTERN WILL CONTINUE THROUGH THIS PERIOD AS
THE STATIONARY FRONTAL BOUNDARY IS FORECAST TO REMAIN IN THE
AREA...ALTHOUGH PRECIP CHANCES WILL VARY A BIT BASED ON TIMING OF
MID LEVEL SHORT WAVE TROUGHS AND MINOR NORTH TO SOUTH FLUCTUATIONS
IN THE LOCATION OF THE FRONT. THE EXACT TIMING OF THE WEAK TROUGHS
AND ASSOCIATED ENHANCEMENTS IN PRECIPITATION COVERAGE REMAINS
RATHER DIFFICULT TO PIN POINT AT THIS TIME...BUT IT CURRENTLY
LOOKS LIKE WEDNESDAY EVENING AND THURSDAY NIGHT-FRIDAY MORNING
WILL HAVE THE BEST CHANCES FOR MORE WIDESPREAD PRECIP ACROSS THE
AREA. EVEN THEN...THE RAIN CHANCES WILL INCREASE FROM NORTH TO
SOUTH ACROSS THE AREA AS THERE IS MORE CONFIDENCE IN THE FRONT
SETTING UP SOUTH OF THE AREA THAN IN A NORTHWARD SHIFT. THE SHORT
WAVE SCHEDULED FOR THURSDAY NIGHT INTO FRIDAY MORNING SHOULD BE
STRONG ENOUGH TO PUSH THE FRONT FARTHER TO THE SOUTH AND BRING IN
DRIER AIR FROM THE NORTH. THIS SHOULD EFFECTIVELY CUT OFF THE
PRECIP CHANCES FROM NORTH TO SOUTH LATE FRIDAY INTO FRIDAY NIGHT.
THE POTENTIAL FOR ISOLATED STRONG STORMS AND ISOLATED HEAVY
RAINFALL AMOUNTS WILL CONTINUE THROUGH THE MAJORITY OF THIS
PERIOD. SEVERE POTENTIAL WILL DECREASE WITH TIME AS INSTABILITY
GRADUALLY WANES WITH WEAKER LAPSE RATES ALOFT. HOWEVER...DEEP
LAYER SHEAR WILL INCREASE A BIT WITH SOME LOCAL MAXIMA IN
INSTABILITY WHICH MAY PRESENT SOME LOCALIZED STRONG TO SEVERE
STORM POTENTIAL. THE HEAVY RAIN POTENTIAL IS A RESULT OF PWAT
VALUES INCREASING TO 1.5 INCHES OR HIGHER...CLIMATOLOGICALLY
HIGH... THE PRESENCE OF WIDESPREAD WEAK TO MODERATE INSTABILITY...
AND STORM MOTIONS THAT MAY OCCASIONALLY SUPPORT TRAINING ALONG OR
NEAR THE FRONTAL BOUNDARY. EVEN WITH HEAVY RAIN POTENTIAL...
FLOODING POTENTIAL APPEARS QUITE LOW GIVEN THE SOIL CONDITIONS...
STREAM BASE FLOW LEVELS...AND AVAILABLE WATER STORAGE IN AREA
LAKES AND PONDS.
HIGHS IN THE 70S ARE EXPECTED ONCE AGAIN THURSDAY AND FRIDAY WITH
AMPLE CLOUD COVER IN PLACE. THE CLOUDS WILL ALSO LIMIT THE DIURNAL
TEMPERATURE SWING SO LOWS SHOULD ONLY DROP INTO THE MIDDLE 50S TO
LOWER 60S.
BARJENBRUCH
LONG TERM - SATURDAY THROUGH TUESDAY...
A RATHER DEEP UPPER TROUGH SETTLES SOUTH INTO THE OHIO VALLEY ON
SATURDAY WITH NORTHERLY FLOW ALOFT AND DRY HIGH PRESSURE AT THE
SURFACE. WHILE THE LONG TERM MODEL GUIDANCE DIFFERS SOMEWHAT IN
OVERALL FLOW SOLUTIONS...THE EXPECTED RESULT IS THE SAME AND A
PERIOD OF DRY STABLE CONDITIONS IS EXPECTED FROM SATURDAY THROUGH
THE END OF THE FORECAST PERIOD ON TUESDAY. THERE ARE SOME
INDICATIONS OF A RATHER PERSISTENT BAND OF FRONTOGENESIS AND
ISENTROPIC ASCENT IN CENTRAL TO WESTERN KANSAS ON THE WESTERN
FLANK OF THE SURFACE HIGH BY LATE IN THE WEEKEND...BUT THIS LOOKS
LIKE A SET UP FOR SPRINKLES AT BEST AND HAVE NOT BROUGHT PRECIP
CHANCES INTO THE FORECAST AT THIS TIME. EXPECT TEMPERATURES
TOPPING OUT IN THE 70S WITH LOWS AROUND 50 ESSENTIALLY EVERY DAY
DURING THIS PERIOD OWING TO NEARLY NEUTRAL TEMPERATURE ADVECTION.
THE OCCASIONAL PRESENCE OF CLOUDS VERSUS CLEAR AND CALM CONDITIONS
OVERNIGHT COULD IMPACT LOWS...BUT THERE IS NO CLEAR SIGNAL AT THIS
TIME POINTING TO ANY NIGHTS BEING PARTICULARLY CLEAR AND COLD.
BARJENBRUCH
&&
.AVIATION...
SHOWERS AND THUNDERSTORMS WILL KICK OFF ALONG AND SOUTH OF
INTERSTATE 35 LATER THIS AFTERNOON...BUT SHOULD STAY AWAY FROM
TERMINALS THROUGH THE END OF THE EVENING HOURS. AROUND 06Z STORMS
WILL APPROACH THE TAF SITES...AND MAY REMAIN NEAR AVIATION
TERMINALS THROUGH THE OVERNIGHT HOURS. EXPECT THAT ROUND OF
T-STORMS TO COME TO AN END BY EARLY MORNING. ANOTHER ROUND OF
T-STORMS MAY FORM DURING THE AFTERNOON ON WED NEAR AVN SITES...BUT
WILL LIKELY TAKE PLACE BEYOND THE TIME FRAME OF THIS FCST
ISSUANCE.
JL
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
651 PM EDT TUE SEP 25 2012
...Updated Aviation Discussion...
.Short Term (This afternoon through Wednesday Night)...
Issued at 331 PM EDT Tue Sep 25 2012
Morning convective complex continues to head eastward through the
coal fields of eastern Kentucky this afternoon. Satellite and
surface observations reveal clearing skies to the west of our area.
Areas west of I-65 have already cleared out and temperatures are on
the way up. Further east, mid-high level cloud debris remain, but
some clearing is expected to occur by late afternoon and early
evening in those areas. Dry conditions are expected for the
remainder of the afternoon as the atmosphere recovers from this
morning`s storminess. Temperatures will increase this afternoon as
the sun comes back out, but we will not have much time to work with
to get readings all that high. Still think that we`ll see maximum
temperature readings in the mid-upper 70s in the far west with upper
60s-lower 70s in the central and mid-upper 60s in the east.
Later this afternoon and evening, the deterministic NCEP models all
agree on redeveloping convection along a frontal boundary draped to
our north/northwest. While the atmosphere over south-central
Indiana and much of north-central Kentucky has been convectively
overturned, the atmosphere across western/southwestern Kentucky has
largely been undisturbed. High resolution model runs from the
LMK-WRF, SPC WRF, the RAP, and the HRRR all show increasing
instability across southern IL, eastern MO, and western Kentucky
this afternoon. Model proximity soundings generally show an
elevated mixed layer atop a fairly moist near-surface layer. Wind
fields are sheared in both speed and direction and strong lapse
rates aloft should promote vigorous convective development along
and ahead of this front. Severe convection is likely to our west
this evening and tonight, but is highly questionable across the LMK
forecast area due to this morning`s convection.
Current thinking is that we`ll see a line of convection develop to
our northwest this evening and then slide toward the Ohio River
later tonight. As this line encounters our worked over airmass,
we`ll likely see the convection continue, since the wind shear is
fairly decent and we`ll have instability aloft. The near surface
environment looks to remain largely stable, so any storms that we
see would likely result in torrential rains, some hail and quite a
bit of cloud to ground lightning. The remnants of this line may
transverse southward into southern Kentucky late tonight, but
instability and wind shear support may decay before the line gets
that far south. Therefore, the highest chances of precipitation
look to be across southern Indiana and portions of northern Kentucky
with lesser chances as one heads southward toward the Tennessee
border. Lows tonight will be milder with readings only cooling into
the upper 50s to the lower 60s.
Slow moving frontal boundary will only drift southward during the
day on Wednesday and likely become quasi-stationary by Wednesday
afternoon. Multiple mid-level impulses will transverse the region
resulting in multiple clusters of convection moving across the
region. In general, the highest probabilities of precipitation for
Wednesday favor southern Indiana and northern Kentucky with lesser
probabilities as one gets down toward the KY/TN border. Overall
convective evolution is very uncertain given the complex mesoscale
processes involved and where boundaries may lay. It is likely that
one or more MCS`s may develop and propagate eastward during the day
and into the evening hours. Severe threat is there with damaging
winds and large hail being the most likely threats. Temperatures
will be tricky, but we have stuck close to the weighted-model
average which results in upper 70s to the lower 80s in the north
with lower 80s across the south. The latest datasets do show some
forecast convergence on a wave approaching the area tomorrow evening
which results in increasing PoP chances for Wednesday night with
this forecast issuance. Lows Wednesday night will be in the 60s.
.Long Term (Thursday through Tuesday)...
Issued at 300 PM EDT Tue Sep 25 2012
Thursday through Friday...
Quasi-stationary front will remain draped east to west across the
Ohio Valley, with a series of upper disturbances riding along it in
zonal flow. Expect intervals of showers and thunderstorms, but these
will be as hard to time as the individual disturbances, so forecast
confidence is quite low.
Path of least regret at this time is to carry chance POPs for most
of the period. As timing becomes more clear on any of the upper
impulses, the POP forecast may be better refined. Temps will run
near normal by day, and above normal by night with abundant cloud
cover. Still plenty of bust potential as any longer episodes of
precip could really limit the diurnal ranges.
Friday night through Tuesday...
Sharp upper trough will dig into eastern Canada and the Great Lakes,
and help to push the front farther south over the weekend. Precip
chances will be suppressed farther into south-central Kentucky
through Saturday night, and then south of the area Sunday into early
next week. Model consensus is coming together with each successive
run, so this is a higher-confidence forecast than Thu-Fri. More of a
polar air mass will knock temperatures slightly below normal, with
highs in the lower/mid 70s and lows in the lower/mid 50s.
&&
.Aviation (00Z TAF Issuance)...
Issued at 650 PM EDT Tue Sep 25 2012
Showers and thunderstorms along a front in southern Indiana will
slowly sink south overnight. This activity has been very slow to
shift southward and have therefore pushed back the timing of VCTS at
SDF and LEX. This activity still looks like it will stay to the
north of BWG both tonight and through much of tomorrow. Will
therefore keep any mention of precipitation out of that TAF. There
will likely be a lull in the rain tomorrow morning until another
upper level disturbance crosses the area tomorrow afternoon,
bringing another round of showers and storms to SDF and LEX.
Winds will decrease to around 6-8 knots overnight out of the south
to southwest. A LLJ will strengthen towards midnight and pivot
across the area. Winds will increase to around 40 knots at 1800-2000
ft. Surface winds will once again increase and become gusty tomorrow.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......MJ
Long Term........RAS
Aviation.........EER
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
332 PM EDT TUE SEP 25 2012
.Short Term (This afternoon through Wednesday Night)...
Issued at 331 PM EDT Tue Sep 25 2012
Morning convective complex continues to head eastward through the
coal fields of eastern Kentucky this afternoon. Satellite and
surface observations reveal clearing skies to the west of our area.
Areas west of I-65 have already cleared out and temperatures are on
the way up. Further east, mid-high level cloud debris remain, but
some clearing is expected to occur by late afternoon and early
evening in those areas. Dry conditions are expected for the
remainder of the afternoon as the atmosphere recovers from this
morning`s storminess. Temperatures will increase this afternoon as
the sun comes back out, but we will not have much time to work with
to get readings all that high. Still think that we`ll see maximum
temperature readings in the mid-upper 70s in the far west with upper
60s-lower 70s in the central and mid-upper 60s in the east.
Later this afternoon and evening, the deterministic NCEP models all
agree on redeveloping convection along a frontal boundary draped to
our north/northwest. While the atmosphere over south-central
Indiana and much of north-central Kentucky has been convectively
overturned, the atmosphere across western/southwestern Kentucky has
largely been undisturbed. High resolution model runs from the
LMK-WRF, SPC WRF, the RAP, and the HRRR all show increasing
instability across southern IL, eastern MO, and western Kentucky
this afternoon. Model proximity soundings generally show an
elevated mixed layer atop a fairly moist near-surface layer. Wind
fields are sheared in both speed and direction and strong lapse
rates aloft should promote vigorous convective development along
and ahead of this front. Severe convection is likely to our west
this evening and tonight, but is highly questionable across the LMK
forecast area due to this morning`s convection.
Current thinking is that we`ll see a line of convection develop to
our northwest this evening and then slide toward the Ohio River
later tonight. As this line encounters our worked over airmass,
we`ll likely see the convection continue, since the wind shear is
fairly decent and we`ll have instability aloft. The near surface
environment looks to remain largely stable, so any storms that we
see would likely result in torrential rains, some hail and quite a
bit of cloud to ground lightning. The remnants of this line may
transverse southward into southern Kentucky late tonight, but
instability and wind shear support may decay before the line gets
that far south. Therefore, the highest chances of precipitation
look to be across southern Indiana and portions of northern Kentucky
with lesser chances as one heads southward toward the Tennessee
border. Lows tonight will be milder with readings only cooling into
the upper 50s to the lower 60s.
Slow moving frontal boundary will only drift southward during the
day on Wednesday and likely become quasi-stationary by Wednesday
afternoon. Multiple mid-level impulses will transverse the region
resulting in multiple clusters of convection moving across the
region. In general, the highest probabilities of precipitation for
Wednesday favor southern Indiana and northern Kentucky with lesser
probabilities as one gets down toward the KY/TN border. Overall
convective evolution is very uncertain given the complex mesoscale
processes involved and where boundaries may lay. It is likely that
one or more MCS`s may develop and propagate eastward during the day
and into the evening hours. Severe threat is there with damaging
winds and large hail being the most likely threats. Temperatures
will be tricky, but we have stuck close to the weighted-model
average which results in upper 70s to the lower 80s in the north
with lower 80s across the south. The latest datasets do show some
forecast convergence on a wave approaching the area tomorrow evening
which results in increasing PoP chances for Wednesday night with
this forecast issuance. Lows Wednesday night will be in the 60s.
.Long Term (Thursday through Tuesday)...
Issued at 300 PM EDT Tue Sep 25 2012
Thursday through Friday...
Quasi-stationary front will remain draped east to west across the
Ohio Valley, with a series of upper disturbances riding along it in
zonal flow. Expect intervals of showers and thunderstorms, but these
will be as hard to time as the individual disturbances, so forecast
confidence is quite low.
Path of least regret at this time is to carry chance POPs for most
of the period. As timing becomes more clear on any of the upper
impulses, the POP forecast may be better refined. Temps will run
near normal by day, and above normal by night with abundant cloud
cover. Still plenty of bust potential as any longer episodes of
precip could really limit the diurnal ranges.
Friday night through Tuesday...
Sharp upper trough will dig into eastern Canada and the Great Lakes,
and help to push the front farther south over the weekend. Precip
chances will be suppressed farther into south-central Kentucky
through Saturday night, and then south of the area Sunday into early
next week. Model consensus is coming together with each successive
run, so this is a higher-confidence forecast than Thu-Fri. More of a
polar air mass will knock temperatures slightly below normal, with
highs in the lower/mid 70s and lows in the lower/mid 50s.
&&
.Aviation (18Z TAF Issuance)...
Issued at 113 PM EDT Tue Sep 25 2012
Convective complex that affected much of the region this morning
continues to head off to the east. Convection has already cleared
KSDF and KBWG, but light-moderate rain showers will continue to
affect KLEX for the first hour of the upcoming TAF period (through
25/19Z).
We expect a lull in the precipitation this afternoon as we`ll be in
the wake of the departing convective complex. Skies and ceilings
are expected to be in the VFR department through much of the
afternoon and into the early evening hours.
Additional convection is expected to develop along a frontal
boundary to our northwest. This frontal boundary is generally along
the I-70 corridor from near KSTL east to KIND. Latest mesoscale
models suggest that convection will develop along this boundary this
afternoon and then eventually sag to the south and southeast this
evening. There are questions regarding the instability across
southern Indiana and northern Kentucky in the wake of this morning`s
convection. Preliminary thinking is that convection may remain
along and north of the Ohio River this evening as per the latest
NCEP models. The higher resolutions models such as the 4km LMK WRF
and 4km SPC WRF suggest that convection may sag into the KLEX and
KSDF terminals after 26/00Z.
Given the low confidence forecast at this time, we plan to just
mention VCTS in at KSDF and KLEX after 26/00Z. For KBWG, conditions
should remain generally VFR this evening and overnight as convection
looks to remain to their north through the TAF period.
Winds this afternoon should generally be out of the south/southwest
and may be gusty at times this afternoon. Feel that gusts will be
less than 20kts. LLWS looks to be a possibility tonight as the
low-level jet should become active once again.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......MJ
Long Term........RAS
Aviation.........MJ
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
322 PM EDT TUE SEP 25 2012
.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO PUSH OFFSHORE THIS EVENING. A COLD
FRONT WILL APPROACH THE CENTRAL MID ATLANTIC WEDNESDAY AND STALL
ACROSS THE REGION THURSDAY INTO THE WEEKEND.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
HIGH PRESSURE HAS MOVED OFFSHORE. RETURN FLOW HAS SET UP ON THE BACK
SIDE OF THE HIGH CENTER. TEMPERATURES ARE BETWEEN 5 AND 7 DEGREES
WARMER THAN THIS TIME YESTERDAY...AND DEWPOINTS ARE AROUND 10
DEGREES HIGHER. VISIBLE SATELLITE IMAGERY SHOWS MID AND HIGH LEVEL
CLOUDINESS SPREADING EASTWARD ACROSS THE REGION FROM A CONVECTIVE
SYSTEM ACROSS THE OHIO VALLEY NORTH OF A WARM FRONT.
REGIONAL RADAR SHOWS SCATTERED SHOWERS ACROSS SOUTHERN WV MOVING
EAST. MOST RECENT RUNS OF THE HRRR BREAK THIS PRECIP UP AS IT
CROSSES THE POTOMAC HIGHLANDS. DO THINK THIS IS REASONABLE AS THE
AIRMASS IS RATHER DRY...AND WILL TAKE A WHILE TO MOISTEN THE COLUMN.
THE BEST CHANCES FOR ANY PRECIP SHOULD BE IN THE WEST LATER THIS
EVENING INTO THE OVERNIGHT HOURS AS THE FRONT APPROACHES. PRECIP
AXIS WILL BECOME W TO E ORIENTED DURING THE DAY TOMORROW AS THE
FRONT BEGINS TO STALL OUT OVER THE CWFA. THE BEST CHANCES FOR PRECIP
TOMORROW SHOULD BE ALONG THE MASON DIXON LINE.
SURFACE INSTABILITY WILL BE LIMITED OVERNIGHT...BUT WITH SOME MID
LEVEL FORCING...ISOLATED THUNDERSTORMS WILL BE POSSIBLE OUT WEST.
THUNDERSTORM CHANCES WILL INCREASE TOMORROW...BUT STILL ONLY REMAIN
SCT IN NATURE.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
A COLD FRONTAL BOUNDARY WILL SETTLE OVER THE REGION THURSDAY INTO
THE WEEKEND...THOUGH PRECIPITATION LOOKS TO GENERALLY BE FROM
SHORTWAVE ENERGY RIDING ALONG THIS BOUNDARY...MAKING PRECISE
PRECIPITATION PREDICTION NOT POSSIBLE AS OF THIS TIME.
WEDNESDAY NIGHT...COLD FRONT PUSHES SOUTH ACROSS THE MASON-DIXON
LINE WITH CHANCE POPS ACROSS THE CWA. MIN TEMPS GENERALLY LOW 60S
UNDER THICK CLOUD COVER.
THURSDAY INTO SATURDAY...COLD FRONT LINGERS ACROSS THE REGION AS LOW
PRESSURE PERSISTS TO THE NORTH OF THE FRONTAL BOUNDARY AND HIGH
PRESSURE TO THE SOUTH. SHORTWAVES FROM THE TROUGH TO THE NORTH LOOK
TO BE MAIN FORCING FOR PRECIP. THEREFORE NO AREA IS EXPECTED TO HAVE
CONTINUAL PRECIP. TOTAL QPF MAY BE HALF INCH...MAYBE MUCH LESS FOR
MOST OF THE AREA WITH PASSING SHOWERS AS THE MAIN CONVECTIVE MODE.
LIFTED INDEX ON THE SOUTH SIDE OF THE FRONT OF -2 TO -4 FROM THE GFS
ALLOWED A SLIGHT CHANCE FOR THUNDER TO BE ADDED /SW OF DC/. EXPECT
NEAR NORMAL TEMPERATURES THROUGH THIS TIME.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
THIS WEEKEND INTO NEXT WEEK...STILL A GREAT DIVERGENCE IN MODELS
WITH A MORE SIGNIFICANT LOW DEVELOPING ALONG THE FRONTAL BOUNDARY AND
PUSHING NORTHEAST. WILL HAVE TO KEEP AN EYE OUT FOR MORE SIGNIFICANT
RAINFALL...THOUGH AS OF NOW THE GFS/ECMWF KEEP DEVELOPMENT OFFSHORE.
&&
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
THICKENING MID AND UPPER LEVEL CLOUDINESS WILL HELP INHIBIT
WIDESPREAD FOG FORMATION OVERNIGHT. SCT SHOWERS ARE
POSSIBLE...MAINLY IN THE WEST TOWARDS SUNRISE.
A COLD FRONT WILL SAG SOUTHWARD ACROSS THE MID ATLANTIC TOMORROW.
SHOWERS AND A FEW THUNDERSTORMS ARE POSSIBLE...MAINLY ALONG THE
BOUNDARY. KMTN AND KBWI HAVE THE BEST CHANCES TO BE IMPACTED BY ANY
SHOWERS/ISO TSRA DURING THE AFTERNOON.
CIGS SHOULD REMAIN WELL ABOVE 3 KFT THROUGH THE TAF PERIOD.
INTERMITTENT OF PRECIPITATION ACROSS THE TERMINALS WEDNESDAY NIGHT
INTO THE WEEKEND AS A SLOW MOVING COLD FRONT SAGS INTO AND STALLS
OVER THE REGION. RAINFALL GENERALLY LIGHT TO MODERATE.
&&
.MARINE...
SOUTHERLY FLOW CONTINUES TO INCREASE ACROSS THE WATERS THIS
AFTERNOON. DO EXPECT WIND GUSTS TO AROUND 20 KT ACROSS THE LOWER
TIDAL POTOMAC AND MD CHES BAY OVERNIGHT. NO CHANGES TO THE HEADLINES
NEEDED.
GUSTY SLY FLOW IN ADVANCE OF A COLD FRONT WEDNESDAY NIGHT...SMALL
CRAFT ADVISORY UP UNTIL 6AM THURSDAY. THIS SCA WILL LIKELY NOT NEED
TO BE EXTENDED AS THE COLD FRONT STALLS OVER THE CHESAPEAKE BAY
REGION THEN INTO THE WEEKEND BRINGING INTERMITTENT LIGHT TO MODERATE
SHOWERS.
&&
.TIDES/COASTAL FLOODING...
WATER LEVELS ARE CURRENTLY RUNNING BETWEEN ONE HALF AND THREE
QUARTERS OF A FOOT ABOVE NORMAL. DO EXPECT GRADUAL RISES IN WATER
LEVELS OVERNIGHT AS PROLONGED SOUTHERLY FLOW CONTINUES. MODEL
FORECASTS DO KEEP VALUES BELOW CRITICAL THRESHOLDS OVERNIGHT.
HOWEVER...MINOR COASTAL FLOODING MAY BE POSSIBLE DURING THE DAY ON
WEDNESDAY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ530-531-
537>543.
SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ532>534.
&&
$$
SYNOPSIS...BAJ/NWL
NEAR TERM...NWL
SHORT TERM...BAJ
LONG TERM...BAJ
AVIATION...BAJ/NWL
MARINE...BAJ/NWL
TIDES/COASTAL FLOODING...NWL
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
421 PM EDT TUE SEP 25 2012
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 420 PM EDT TUE SEP 25 2012
WV IMAGERY AND RUC ANALYSIS INDICATED MID/UPPER LEVEL LOW JUST EAST
OF HUDSON BAY WITH TROUGHING TO THE SOUTH DOMINATING THE GREAT LAKES
AND NE CONUS. AN UPSTREAM SHORTWAVE TROUGH WAS LOCATED NW OF LAKE
SUPERIOR AND HELPED SUPPORT AN INCREASE IN SCT DIURNAL SHOWERS FROM
WINNIPEG TO THUNDER BAY ONTARIO. SOME SPRINKLES HAVE ALSO DEVELOPED
EAST OF THE KEWEENAW AND INTO THE HURON MOUNTAINS WITH THE HELP OF
AFTERNOON HEATING AND WEAK LAKE BREEZES. A WEAK PRES GRADIENT AND
WIND FIELD PREVAILED AS HIGH PRESURE FROM SASK/MANITOBA BUILDS INTO
THE NRN GREAT LAKES.
EXPECT SHRA WILL INCREASE LATE TONIGHT AS 850 MB TEMPS FALL TOWARD
-1C AND A WEAK SFC TROF DROPS S ACROSS THE LAKE IN ASSOCIATION WITH
THE SHORTWAVE. WITH LAKE TEMPS ONLY AROUND 10C TO 13C...DELTA/T
VALUES WILL BE MARGINAL FOR LAKE EFFECT PCPN BUT WILL BE AIDED BY
THE SHRTWV/COLD POOL WITH 700 MB TEMPS ALSO DROPPING TO AROUND
-10C.
THE TIMING OF THE TROF WILL ALSO COINCIDE WITH THE MORE FAVORABLE
MIN OF THE DIURNAL CYCLE. WITH LARGE SCALE SUBSIDENCE WITH DIVERGENT
LOW LEVEL ACYC FLOW AND A SHORTER FETCH...LEFT OUT MENTION OF SHRA
WEST OF THE KEWEENAW. AWAY FROM ANY THICKER CLOUDS AND LAKE
INFLUENCE... TEMPS WILL AGAIN DROP AOB FREEZING IN MANY LOCATIONS
OVER THE INTERIOR WEST. ANY LINGERING SHRA IN THE MORNING INTO THE
ERN CWA FAVORED BY NW FLOW WILL DIMINISH AND END BY AFTERNOON AS THE
SFC RIDGE CONTINUES TO BUILD INTO THE AREA.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 420 PM EDT TUE SEP 25 2012
SPLIT FLOW REGIME TO DOMINATE IN THE UPPER LEVELS THROUGH NEXT
WEEKEND WITH HEIGHTS OVER UPPER LAKES STAYING GENERALLY HIGH. ONE
NOTABLE EXCEPTION IS ECMWF AND TO SOME DEGREE GEM-NHEM STILL SHOW
SHORTWAVE TROUGH SLIDING EAST ACROSS NORTHERN CANADA THIS WEEK THEN
DROPPING INTO NORTHERN ONTARIO ON SATURDAY AND THROUGH THE UPPER
GREAT LAKES BY SUNDAY. ECMWF IS FARTHEST WEST WITH UPPER LOW CENTER
AND SUPPOSE WITH ITS SOLUTION THERE COULD END UP BEING SOME SHOWERS
OVER EASTERN CWA SECOND HALF OF THE WEEKEND. ECMWF HAS SHOWN THIS
FOR FOUR MODEL RUNS NOW...SINCE THE 00Z RUN ON 24 SEPT. GFS REALLY
SHOWS NOTHING OF THE SORT WHILE THE GEM-NHEM IS MORE MIDDLE OF THE
ROAD. CONSENSUS POPS KEEPS THINGS DRY FOR NOW...BUT WENT AHEAD AND
NUDGED CLOUD COVER UP OVER THE EAST LATER SATURDAY THROUGH SUNDAY.
WEAK SHORTWAVE TROUGH SLIDES THROUGH AREA NEXT MONDAY BUT LIMITED
MOISTURE RESULTS IN ONLY SLIGHT CHANCES IN THE FORECAST FOR NOW WITH
THE APPROACH OF A SFC TROUGH. PRIMARY IMPACT COULD BE GUSTY SW WINDS
AHEAD OF THE TROUGH SUNDAY INTO MONDAY.
MAIN WEATHER ISSUE THROUGH THE LONG TERM SEEMS TO BE TEMPERATURES
AND FROST/FREEZE POTENTIAL. NOTE THAT EVEN THOUGH WE HAVE
TECHNICALLY ENDED THE FROST/FREEZE PROGRAM FOR THIS FALL AS MANY
AREAS OVER THE REGION HAVE EXPERIENCED BLO FREEZING TEMPS
RECENTLY...MENTION OF FROST IN THE GRIDS REMAINS IN PLACE THROUGH 30
SEPT.
HIGH PRESSURE RIDGE SETTLES OVER THE UPPER LAKES LATER WEDNESDAY
INTO WEDNESDAY EVENING. HIGHS REMAINS OVERHEAD THROUGH SATURDAY.
GIVEN MOSTLY CLEAR SKIES AND RELATIVELY DRY AIR...EXPECT LARGER
DIURNAL TEMPERATURE SWINGS WITH HIGHS WELL INTO THE 60S AND MINS
DIPPING INTO THE 30S. COLDER EXCEPTION WILL BE WEDNESDAY NIGHT AS
RIDGE AXIS DIRECTLY OVERHEAD AND PWATS AS LOW AS 40 PCT OF NORMAL
SHOULD LEAD TO SIGNIFICANT RADIATIONAL COOLING. TWEAKED MINS WELL
BLO FREEZING OVER INTERIOR CWA /LOW-MID 20S FOR FAVORED INLAND COLD
SPOTS/. LACK OF WIND/LAND BREEZE SHOULD EVEN RESULT IN SOME FROST
FORMING PRETTY CLOSE TO THE GREAT LAKES SHORES. WARMER EXCEPTION MAY
BE ON FRIDAY AS BUBBLE OF WARMER AIR ALOFT MOVES ACROSS OUT AHEAD OF
THE UPPER LOW DROPPING ACROSS ONTARIO. POSSIBLE THAT SOME READINGS
COULD PUSH INTO THE 70S IF ALL BREAKS RIGHT. LOWERED DWPNTS SOME FOR
THURSDAY AFTN AND FRIDAY AFTN AS H85 DWPNT DEPRESSIONS ARE HIGHER
THROUGH THAT TIME. EVEN SO...NO FIRE WEATHER CONCERNS ARE EXPECTED
SINCE WINDS STAY LIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 140 PM EDT TUE SEP 25 2012
AN INCREASE IN OVERWATER INSTABILITY AND AN INCREASE IN LOW-LEVEL
MOISTURE FROM THE N...AND DAYTIME HEATING WILL SUSTAIN BKN STRATOCU
THIS AFTERNOON WITH VFR CIGS. COLDER AIR MOVING IN BEHIND A SHRTWV
LATER TONIGHT ALONG WITH A FURTHER INCREASE IN LOW LEVEL MOISTURE
SHOULD LOWER CIGS INTO THE MVFR RANGE. HOWEVER...CONFIDENCE REMAINS
LIMITED WITH RESPECT TO TIMING/CHANCES OF ANY LOWER CIGS.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 420 PM EDT TUE SEP 25 2012
HIGH PRES/WEAK PRES GRADIENT WILL GENERALLY DOMINATE FOR THE REST OF
THIS WEEK...RESULTING IN WINDS UNDER 20KT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
142 PM EDT TUE SEP 25 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 511 AM EDT TUE SEP 25 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS CONTINUE TO SHOW A TROF OVER SE
CANADA INTO THE NE CONUS. REINFORCING SHORTWAVE TROF DROPPED THRU
THE UPPER LAKES LAST EVENING...BRINGING ANOTHER PUSH OF COOLER AIR
INTO THE AREA. AFTER THE SURGE OF WARMER AIR YESTERDAY ON GUSTY W/SW
WINDS AHEAD OF SHORTWAVE...850MB TEMPS ARE BACK DOWN TO 0C ACROSS
LAKE SUPERIOR...BUT ARE STILL AROUND 5C OVER THE FAR SCNTRL FCST
AREA PER LATEST RUC ANALYSIS. RELATIVELY DRY AIR HAS ALSO FOLLOWED
SHORTWAVE INTO UPPER MI...BUT UPSTREAM CWPL SOUNDING AT 00Z SHOWED
NEAR SATURATION FROM ABOUT 900MB TO 700MB. ALTHOUGH RECENT SATELLITE
IMAGERY SHOWS A SLIGHT INCREASE IN LAKE EFFECT CLOUDS...COVERAGE IS
STILL VERY LIMITED. NO SHRA ARE EVIDENT. TO THE N...CANADIAN RADARS
SHOW SOME -SHRA OFF LAKE NIPIGON.
MAIN CONCERN IN THE SHORT TERM WILL MAINLY BE LAKE EFFECT SHRA
POTENTIAL. SHORTWAVE UPSTREAM IN ERN MANITOBA AND FOLLOWING PIECE OF
ENERGY A LITTLE FARTHER N WILL BE ENHANCING FACTORS FOR SHRA
DEVELOPMENT. WITH DEEP LAYER FORCING PER QVECTORS SPREADING OVER THE
AREA TODAY ALONG WITH AN INCREASE IN LOW-LEVEL MOISTURE...EXPECT SOME
-SHRA DEVELOPMENT...BUT THE DISRUPTION OF LAKE EFFECT PROCESSES BY
DAYTIME HEATING WILL BE A SIGNIFICANT NEGATIVE FACTOR. PERIODIC
HEAVY WAVE ACTION ON LAKE SUPERIOR OVER THE LAST WEEK OR SO HAS
RESULTED IN MID LAKE WATER TEMPS FALLING TO 10-13C WHILE READINGS
AROUND 15-16C ARE PROBABLY STILL MORE COMMON OVER THE SRN PORTION OF
THE LAKE. SO OVERWATER INSTABILITY IS A LITTLE MORE MARGINAL...
ESPECIALLY FOR THE MORE DISRUPTIVE DAYTIME HRS. AT THIS POINT...
NOTHING MORE THAN SCHC POPS APPEAR WARRANTED...MAINLY OVER THE
NCNTRL FCST AREA AS DRIER AIR TO THE W SHOULD PREVENT ANY SHRA
DEVELOPMENT OFF WRN LAKE SUPERIOR.
SHRA COVERAGE SHOULD TEND TO INCREASE LATE TONIGHT AS 850MB TEMPS
FALL TOWARD -2C AND A WEAK SFC TROF DROPS S ACROSS THE LAKE IN
ASSOCIATION WITH SHORTWAVE. TIMING OF TROF WILL ALSO COINCIDE WITH
THE MORE FAVORABLE MIN OF THE DIURNAL CYCLE. THUS...HAVE POPS
INCREASING TO CHC OVER THE NCNTRL/NE FCST AREA LATE TONIGHT. LEFT
THE W DRY DUE TO LARGER AREA OF COOLER WATER OVER THE WRN LAKE AND
DUE TO DEEP LAYER QVECTOR DIVERGENCE DOMINATING. SOME OF THE HIGH
RES MODEL GUIDANCE INDICATES -SHRA WILL OCCUR OVER THE W...SO WILL
NEED TO REEXAMINE POTENTIAL AGAIN IN LATER FCSTS. IN THE INTERIOR W
TONIGHT...THERE SHOULD BE A SUFFICIENT LACK OF CLOUDS TO ALLOW TEMPS
TO FALL TO AROUND 30F...RESULTING IN FROST DEVELOPMENT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 511 AM EDT TUE SEP 25 2012
SHORTWAVE WILL BE EXITING THE CWA TO THE SE AT THE START OF THE
PERIOD...SETTING UP A PERIOD OF SPLIT FLOW THROUGH THE END OF THE
WEEK. THE NRN STREAM WILL BE SET IN CANADA...WHILE THE SRN STREAM
WILL BE OVER THE SRN HALF OF THE CONUS. THIS WILL ALLOW FOR HIGH
PRESSURE TO SETTLE IN AND PRODUCE A FAIRLY DRY LONG TERM PERIOD.
FORCING FROM THE SHORTWAVE...COMBINING WITH A POCKET OF LLVL
MOISTURE...SHOULD ALLOW SHOWERS TO BE ONGOING OVER SCNTRL/ERN LAKE
SUPERIOR AND ERN UPPER MI. THESE SHOWERS WILL BE AIDED BY ENHANCED
LLVL CONVERGENCE AND INCREASED LK INSTABILITY WITH H850 TEMPS AROUND
1C. THE SHOWERS SHOULD CONTINUE THROUGH MUCH OF THE MORNING...BUT
HIGH PRESSURE BUILDING IN AND THE QUICKLY EXITING SHORTWAVE/MOISTURE
SHOULD BRING A DIMINISHING TREND IN THE EARLY AFTERNOON.
ANTICYCLONIC FLOW INCREASING THROUGH THE DAY AND DRYING ALOFT
LOWERING THE CAPPING INVERSION WILL ALSO DIMINISH THE SHOWERS. WITH
THE CLOUDS IN PLACE FOR MUCH OF THE DAY...EXPECT HIGHS TO ONLY RISE
INTO THE 50S...WITH THE COOLEST VALUES OVER THE N WHERE THE CLOUD
COVER WILL BE THE THICKEST.
THIS HIGH WILL REMAIN IN PLACE THROUGH AT LEAST THURS NIGHT AND LEAD
TO DRY WX OVER UPPER MI. EXPECT A COLD NIGHT WED NIGHT WITH THE HIGH
BEING NEARLY OVERHEAD. PWATS AROUND 50 PERCENT OF NORMAL AND CLEAR
SKIES WILL PROMOTE RADIATIONAL COOLING AND EXPECT LOWS IN THE UPPER
20S AND LOWER 30S OVER MOST INTERIOR LOCATIONS. THIS WILL PRODUCE
ANOTHER DECENT FROST/FREEZE ACROSS THE AREA. SINCE MOST INTERIOR
LOCATIONS HAVE SEEN A FROST OR FREEZE ALREADY THIS MONTH...OUR
ADVISORY/WARNING HEADLINES HAVE ENDED...BUT WILL CONTINUE TO MENTION
FROST DURING THE TRANSITION PERIOD.
OTHER THAN SOME DIURNAL CU OVER THE SE HALF OF UPPER MI THURS
AFTN...EXPECT MOSTLY CLEAR SKIES TO CONTINUE ON THURS AND INTO FRI.
GRADUALLY WARMING H850 TEMPS WILL LEAD TO HIGHS RISING INTO THE 60S
FOR THURS/FRI...WHICH IS BACK TO NORMAL.
THE GREATEST UNCERTAINTY FOR THE LONG TERM FORECAST COMES WITH THE
SHORTWAVE THAT MOVES THROUGH THE NRN STREAM IN ONTARIO ON FRI. THIS
WILL DRAG A WEAK COLD FRONT ACROSS UPPER MI LATE THURS NIGHT AND
INTO FRI...BUT WILL ONLY CAUSE A SLIGHT WINDSHIFT.
THEN...DETERMINISTIC AND ENSEMBLE MODELS ARE STARTING TO TREND
TOWARDS THE SHORTWAVE BECOMING CLOSED/CUT OFF OVER FAR SE ONTARIO ON
SAT AND SLOWLY DRIFTING SSW INTO THE GREAT LKS. CONFIDENCE IS
INCREASING ON THIS OCCURRENCE...BUT THE LOCATION VARIES DEPENDING
ON THE MODEL. AT THIS POINT...WITH MOISTURE NOT EXPECTED TO BE TOO
FAR FROM THE SHORTWAVE WHILE MOVING THROUGH ONTARIO...DON/T THINK
THERE WILL BE MUCH MOISTURE TO WORK WITH WHEN THE TROUGH CUTS OFF.
THEREFORE...WILL CONTINUE TO FOLLOW A DRY FORECAST FOR THE WEEKEND
AS THE GENERAL CONSENSUS OF THE MODELS HAS THE UPPER LOW CENTERED
OVER LK HURON AND WEAK HIGH PRESSURE OVER THE CWA. RIGHT NOW
TEMPERATURES APPEAR TO BE SEASONABLE FOR THE END OF THE WORK WEEK
AND INTO THE WEEKEND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 140 PM EDT TUE SEP 25 2012
AN INCREASE IN OVERWATER INSTABILITY AND AN INCREASE IN LOW-LEVEL
MOISTURE FROM THE N...AND DAYTIME HEATING WILL SUSTAIN BKN STRATOCU
THIS AFTERNOON WITH VFR CIGS. COLDER AIR MOVING IN BEHIND A SHRTWV
LATER TONIGHT ALONG WITH A FURTHER INCREASE IN LOW LEVEL MOISTURE
SHOULD LOWER CIGS INTO THE MVFR RANGE. HOWEVER...CONFIDENCE REMAINS
LIMITED WITH RESPECT TO TIMING/CHANCES OF ANY LOWER CIGS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 511 AM EDT TUE SEP 25 2012
HIGH PRES/WEAK PRES GRADIENT WILL GENERALLY DOMINATE FOR THE REST OF
THIS WEEK...RESULTING IN WINDS UNDER 20KT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...JLB
MARINE...ROLFSON
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1243 PM CDT TUE SEP 25 2012
.UPDATE...
.DISCUSSION...
ISOLATED SHOWERS CONTINUE TO MOVE EAST ALONG AND SOUTH OF NEBRASKA
HIGHWAY 2. THE FCST HAS BEEN UPDATED AND ALLOWS THESE SHOWERS TO
DRIFT EAST THIS AFTERNOON. GIVEN THE ELEVATED MIXED LAYER
CAPE AND WEAK WIND FIELDS AT ALL LEVELS...THUNDER WILL CONTINUE IN THE
FCST BUT JUST A RUMBLE OR TWO SHOULD BE EXPECTED.
&&
.AVIATION...
VFR IS EXPECTED ALL AREAS THIS AFTERNOON THROUGH WEDNESDAY
MORNING.
A WEAK UPPER LEVEL DISTURBANCE WILL DRIFT EAST THIS AFTERNOON AND
THIS EVENING PRODUCING ISOLATED SHRA AND PERHAPS A THUNDERSTORM OR
TWO. NO LIGHTNING HAS BEEN DETECTED THUS FAR. CIGS SHOULD OPERATE
AT BKN070 OVC150 IN THE SHRA/TSTM ACTIVITY.
&&
.PREV DISCUSSION... /ISSUED 1003 AM CDT TUE SEP 25 2012/
UPDATE...
DISCUSSION...
UPDATE TO THE FORECAST FOR THE ISOLATED SHOWERS DEVELOPING IN
CONJUNCTION WITH A WEAK UPPER LEVEL DISTURBANCE ACROSS WRN
NEBRASKA. LAPSE RATES ARE STEEP AT KDNR AND KLBF SO WE MIGHT SEE
SOME ISOLATED THUNDER. THE RUC SHOWS NO QPF WHILE THE HRRR IS
PUMPING OUT LOTS OF RADAR RETURNS BUT LITTLE ACCUMULATION.
THINKING IS THAT THE RADAR RETURNS WILL WEAKEN AS THEY ENCOUNTER DRY
AIR FARTHER EAST AND DISSIPATE BEFORE REACHING HIGHWAY 83. WE
WILL SEE LATER THIS MORNING.
PREV DISCUSSION... /ISSUED 650 AM CDT TUE SEP 25 2012/
AVIATION...
FOR THE KLBF AND KVTN TERMINALS 12Z TAFS.
UPPER LEVEL LOW PRESSURE WILL MOVE INTO THE CENTRAL ROCKIES TODAY.
THIS FEATURE WILL SPREAD ABUNDANT HIGH CLOUDINESS TO WESTERN NEBRASKA
WITH CIGS RANGING FROM 10000 TO 15000 FT AGL. ONLY THIN HIGH
CLOUDINESS AOA 20000 FT IS FORECAST ACROSS NORTHERN NEBRASKA.
WINDS OVER THE NEXT 24 HOURS WILL BE LIGHT AND VARIABLE THROUGH
17Z. THEREAFTER...EXPECT LIGHT EASTERLY WINDS AT UNDER 10 KTS
THROUGH 06Z WEDNESDAY.
PREV DISCUSSION... /ISSUED 415 AM CDT TUE SEP 25 2012/
DISCUSSION...
PRIMARY FORECAST CONCERNS FOR THIS FORECAST CYCLE INCLUDE
PRECIPITATION CHANCES THROUGH SATURDAY AND TEMPERATURES THROUGH
THE SAME TIME PERIOD
WATER VAPOR IMAGERY THIS MORNING SHOWED LONGWAVE TROUGH OVER THE
NORTHEAST QUARTER OF THE COUNTRY...WITH THE UPPER LOW CENTERED
OVER HUDSON BAY. A SECOND LONGWAVE TROUGH WAS SEEN OVER THE
NORTHERN PACIFIC OCEAN...WITH A FAIRLY STRONG SHORTWAVE TROUGH
JUST DOWNSTREAM OF THE PACIFIC TROUGH INTO WESTERN CANADA AND THE
PACIFIC NORTHWEST. RIDGING WAS IN PLACE BETWEEN THESE
SYSTEMS...WHICH EXTENDED INTO NORTH CENTRAL CANADA. THE GENERAL
FLOW IMPACTING THE LOCAL AREAS WAS NORTHWEST FLOW...WHILE PICKING
OUT SEVERAL SHORTWAVE TROUGHS. THE FIRST WAS OVER EASTERN SOUTH
DAKOTA....WHILE A SECOND WAS OVER SOUTHERN SASKATCHEWAN AND
ANOTHER OVER EASTERN MANITOBA. THERE WAS ALSO SOME SOUTHERN STREAM
INFLUENCE AS AN UPPER LEVEL LOW CENTERED OVER THE NEVADA/UTAH
BORDER ATTEMPTED TO HELP SOME WEAK UPPER LEVEL RIDGING TO BUILD
INTO EASTERN COLORADO THIS MORNING. AHEAD OF THE RIDGING WAS A
WEAK MID LEVEL IMPULSE OVER NORTHERN KANSAS WHICH DID HELP THE
DEVELOPMENT OF SOME SHOWERS FROM SOUTHWEST NEBRASKA INTO NORTHERN
KANSAS THIS MORNING. THE NEXT IMPULSE OF ENERGY SEEN WITH THE
UPPER LOW WAS MOVING ACROSS SOUTHERN COLORADO THIS MORNING.
AT THE SURFACE HIGH PRESSURE HAD SETTLED IN OVER NORTHWEST
NEBRASKA...WHICH HAS ALLOWED TEMPERATURES TO DROP SIGNIFICANTLY
WITH READINGS CURRENTLY IN THE LOW 40S. OTHERWISE...A STATIONARY
FRONT WAS SEEN FROM EASTERN WYOMING INTO EASTERN COLORADO...WHILE
ANOTHER COLD FRONT WAS OBSERVED ACROSS SOUTHERN MINNESOTA AND INTO
CENTRAL SOUTH DAKOTA....BEING DRIVEN BY THE SHORTWAVE OVER SOUTH
DAKOTA.
GETTING SOME ECHOES ON RADAR OVER SOUTHERN NEBRASKA THIS MORNING
WITH THE WAVE MOVING SOUTH OF THE AREA THIS MORNING. OBSERVATION
SITES WERE NOT REGISTERING ANY CLOUDS BELOW 10K FEET ONLY A TRACE
OF RAINFALL HAD BEEN REPORTED AT A FEW SITES WITH THESE PASSING
SHOWERS. THIS WOULD CORRELATE WELL WITH THE OBSERVED 25.00Z
SOUNDING FROM LBF WHICH SHOWED VERY DRY AIR BELOW 600MB TO
EVAPORATE AY RAINFALL BEFORE HITTING THE SURFACE.
SHORT TERM...TODAY THROUGH THURSDAY NIGHT
THE ACTIVITY ON RADAR SHOULD DECREASE THIS MORNING AS THE
SHORTWAVE OVER NORTHERN KANSAS PUSHES EAST. DID INCLUDE SPRINKLES
IN THE FORECAST FOR THE SOUTHWEST COUNTIES WITH THESE SHOWERS BUT
THEY SHOULD END BY NOON.
TODAY...THE SHORTWAVE OVER SOUTHERN COLORADO WILL MOVE INTO EASTERN
COLORADO...BUT THEN GETS CAUGHT IN THE SOUTHWEST FLOW WHICH KEEPS
THE MAJORITY OF THE ENERGY ACROSS KANSAS. COULD SEE FURTHER
DEVELOPMENT OF HIGH BASED SHOWERS AND ISOLATED THUNDERSTORMS
ASSOCIATED WITH THIS ENERGY...BUT EXPECT IT TO STAY ACROSS THE FAR
WESTERN PARTS OF THE FORECAST AREA. WITH A GOOD AMOUNT OF MOISTURE
IN THE MID AND HIGH LEVELS ASSOCIATED WITH THE UPPER LOW WILL
CONTINUE TO SEE PARTLY TO MOSTLY CLOUDY SKIES ACROSS THE SOUTHWEST
HALF OF NEBRASKA TODAY. THIS WILL BE THE TREND FOR THE NEXT
SEVERAL DAYS AS WELL...WHILE THE UPPER LOW STAYS OFF TO THE WEST
OF THE FORECAST AREA. TEMPERATURES ALOFT WARM SLIGHTLY FROM
YESTERDAY SO EXPECT HIGHS A FEW DEGREES WARMER TODAY DESPITE THE
CLOUD COVER. THE WARMEST READINGS SHOULD BE OVER NORTH CENTRAL
NEBRASKA WHERE SUNSHINE SHOULD BE PLENTIFUL.
FOR WEDNESDAY...THE MAIN UPPER LOW PROGRESSES EAST INTO COLORADO.
AS SAID ABOVE...MOISTURE WILL CONTINUE TO BE PULLED INTO THE
REGION AHEAD OF THE SYSTEM...BUT MAINLY IN THE MID LEVELS /ABOVE
700MB/. MEANWHILE...DRY HIGH PRESSURE WILL REMAIN IN PLACE OVER
THE UPPER MISSISSIPPI RIVER VALLEY REGION. EASTERLY FLOW WILL
CONTINUE TO PULL DRY AIR INTO NEBRASKA IN THE LOWER LEVELS TO KEEP
THE AIR VERY DRY IN THE BOUNDARY LAYER. ALTHOUGH...SHOWERS MAY
DEVELOP ON WEDNESDAY AS INCREASED LIFT ASSOCIATED WITH THE UPPER
LEVEL LOW MOVES INTO WESTERN NEBRASKA...THE VERY DRY AIR IN THE
BOUNDARY LAYER WILL PROHIBIT THE AREA FROM SEEING A GOOD CHANCE
FOR MEASURABLE RAINFALL. WILL NOT CHANGE MUCH FROM PREVIOUS
FORECAST...KEEPING ONLY A SLIGHT CHANCE FOR MEASURABLE RAIN
WEDNESDAY.
THE CLOSED LOW WILL MIGRATE EAST AND BECOME AN OPEN WAVE THURSDAY
AND THURSDAY NIGHT. THE MAIN CIRCULATION LOOKS TO TRACK ALONG THE
NEBRASKA KANSAS BORDER...WHICH WILL BRING THE HIGHEST CHANCE FOR
RAIN THROUGH THESE PERIODS. IN ADDITION...THE SHORTWAVE TROUGH
CURRENTLY OVER THE PACIFIC NORTHWEST WILL TRACK INTO THE NORTHERN
PLAINS WHICH WILL DRIVE A PACIFIC COLD FRONT TOWARDS THE AREA. IN
ADDITION TO THE RAIN CHANCES WITH THE UPPER LOW...THERE COULD BE
SOME DEVELOPMENT OF THUNDERSTORMS AHEAD OF THIS COLD FRONT WHICH
WOULD MAINLY IMPACT PARTS OF THE PANHANDLE AND WESTERN SANDHILLS.
AGAIN...DRY AIR WILL BE IN PLACE IN THE LOWER LEVELS SO DON/T HAVE
A LOT OF CONFIDENCE ON THE COVERAGE OF ANY RAIN. SO HAVE CONTINUED
THE LOWER CHANCES THROUGH THIS TIME PERIOD.
LONG TERM...FRIDAY THROUGH MONDAY
MODEL SOLUTIONS DIVERGE FURTHER WITH TIME GOING INTO THE WEEKEND.
THE UPPER LEVEL TROUGH OVER THE NORTHERN PLAINS MENTIONED ABOVE
WILL CONTINUE TO HAVE SOME IMPACT ON THE FORECAST AREA THROUGH THE
FIRST PART OF THE WEEKEND. THE MAIN ISSUES WITH HOW THIS
PROGRESSES IS FROM HOW THE UPPER LOW OVER THE GREAT LAKES BEHAVES. THERE
ARE INDICATIONS THAT IT WILL NOT SEE MUCH MOVEMENT /IF THE ECMWF
VERIFIES KEEPING THE UPPER LOW OVER THE GREAT LAKES/FROM THURSDAY
NIGHT THROUGH SATURDAY...KEEPING THE COLD FRONT ACROSS THE HIGH
PLAINS. THIS WOULD LEAD TO POTENTIAL FOR STORMS AND SHOWERS BOTH
FRIDAY AND SATURDAY. ON THE OTHER HAND...IF THE NORTHEAST SYSTEM
IS MORE PROGRESSIVE WHICH WOULD MEAN A DRY FORECAST. WITH LOW
CONFIDENCE...KEPT THE FORECAST DRY THIS CYCLE.
FIRE WEATHER...
SEVERAL DAYS WILL SEE LOW RELATIVE HUMIDITY IN THE
AFTERNOON...HOWEVER WINDS THESE DAYS ARE NOT FORECAST TO BE
PARTICULARLY STRONG. CURRENTLY WEDNESDAY AND THURSDAY LOOK TO SEE
THE STRONGEST WINDS /WITH GUSTS TO 20 MPH/...HOWEVER RELATIVE
HUMIDITY BOTH DAYS SHOULD BOTTOM OUT AROUND 25 PERCENT. AT THIS
POINT DO NOT EXPECT THE NEED FOR ANY FIRE WEATHER HEADLINES IN THE
NEXT WEEK.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...POWER
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
240 PM EDT TUE SEP 25 2012
.SYNOPSIS...
AN AREA OF HIGH PRESSURE OFF THE VIRGINIA COAST WILL CONTINUE TO
EXTEND ACROSS THE CAROLINAS TONIGHT AND WEDNESDAY....THEN WEAKEN AND
DRIFT EAST BY THURSDAY. THIS WILL INITIATE A WARMING TREND RESULTING
IN ABOVE NORMAL AFTERNOON TEMPERATURES THROUGH THE REMAINDER OF THE
WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 240 PM TUESDAY...
1026MB SURFACE HIGH PRESSURE CENTERED JUST EAST OF NORFOLK THIS
EXTENDS SOUTH ALONG THE NC/SC COASTAL PLAIN THIS AFTERNOON.
SOUTHERLY RETURN FLOW AROUND THE HIGH HAS DEVELOPED ACROSS MOST OF
THE CWA...ALLOWING DEWPOINTS TO SLOWLY CREEP BACK INTO THE LOWER
50S. UPSTREAM CONVECTION OVER EASTERN KY IS MOSTLY ELEVATED...BUT
IS A LITTLE MORE IMPRESSIVE THAN HI-RES GUIDANCE SUGGESTED EARLIER
THIS MORNING. RAP FORECAST SOUNDINGS SUGGEST THE STRONG CAPPING
INVERSION ON THE 12Z KGSO RAOB HAS ERODED A BIT TODAY VIA WEAK
COOLING AROUND 700MB...WITH MODEST MID LEVEL LAPSE RATES ABOVE.
HOWEVER... PW EAST OF THE MOUNTAINS IS STILL AROUND 0.5" AND MUCAPE
IS VERY WEAK. ONLY THE MOST RECENT HRRR RUNS SHOW ANY SIMULATED
ECHOS EAST OF THE MOUNTAINS...AND EVEN THEN ARE ONLY A COUPLE
ISOLATED SHOWERS NEAR FORSYTH AND PERSON COUNTIES. WHILE THE RADAR
AND MODEL TRENDS ARE NOT DISCOUNTED...EXPECT THE ONLY IMPACT TO BE
FROM MID AND HIGH CLOUDS OVER THE NORTHWEST PIEDMONT THIS EVENING.
TONIGHT...
LOWS TONIGHT SHOULD NOT BE NEARLY AS COOL DUE TO THE DEWPOINT
RECOVERY TODAY...HELD HIGHER BY MORE CLOUD COVER OVER THE WESTERN
PIEDMONT...WITH MID 50S WEST TO SOME LOWER 50S EAST. PATCHY FOG IS
ALSO POSSIBLE TONIGHT AND SEEMS MOST LIKELY OVER THE SANDHILLS AND
COASTAL PLAIN.
WEDNESDAY AND WEDNESDAY NIGHT...
A STRENGTHENING FRONTAL ZONE STRETCHING FROM THE MID MS RIVER VALLEY
TO THE OHIO VALLEY REGION WILL SINK SLOWLY SOUTHEASTWARD WEDNESDAY
AND BE ORIENTED WEST TO EAST FROM MO TO NORTHERN VA BY WEDNESDAY
NIGHT. THE SURFACE HIGH...WHILE WEAKENING AND SHIFTING FURTHER
OFFSHORE...WILL STILL EXTEND ACROSS NC FOR MOST OF THE DAY. PW WILL
CONTINUE TO CREEP UP TOWARD ON INCH...BUT DESPITE FORECAST SOUNDINGS
SHOWING THE STEEPER MID LEVEL LAPSE RATES LINGERING...MODELS SHOW
ALL CONVECTION WELL NORTH OF THE NC/VA BORDER WHERE A BETTER
PREFRONTAL INSTABILITY AXIS WILL LIE. 850MB TEMPS ARE FORECAST TO
RISE TO AROUND 18C WEDNESDAY AFTERNOON...THOUGH MIXING MAY NOT REACH
QUITE TO 850MB. MIXING TO 925MB INSTEAD YIELDS MOSTLY MID 80S AREA
WIDE. LOWS WEDNESDAY NIGHT AGAIN IN THE LOW TO MID 50S.
&&
.SHORT TERM /THURSDAY AND FRIDAY NIGHT/...
AS OF 240 PM TUESDAY...
MODELS IN ROUGH AGREEMENT IN DEPICTING A WEAK SHORT WAVE MOVING
THROUGH VIRGINIA AND THE CAROLINAS LATE THURSDAY INTO FRIDAY
MORNING. A WEAK FRONT ALONG THE OHIO VALLEY BECOME MORE EAST WEST
ORIENTED AND SLIPS SOUTHWARD IN RESPONSE TO THIS WAVE. WINDS AND
DYNAMICS WITH THIS FRONT CONTINUE QUITE WEAK AND THIS PERIOD MAY
TURN OUT DRY. CURRENTLY BELIEVE THE FRONT WILL REMAIN NORTH IN
VIRGINIA DURING THIS PERIOD. THE BEST RAIN CHANCE IN CENTRAL NORTH
CAROLINA WILL BE LIMITED TO SLIGHT IN THE EXTREME NORTH AND
NORTHWEST... FRIDAY AFTERNOON INTO FRIDAY NIGHT.
THURSDAY STILL LOOKS LIKE THE WARMEST DAY OF THE WORK WEEK WITH LOW
LEVEL THICKNESSES FALLING SLIGHTLY FRIDAY IN RESPONSE TO THE SHORT
WAVE. AFTERNOON HIGH TEMPERATURES 83 TO 88 THURSDAY...82 TO 85
FRIDAY. LOW TEMPERATURES 59 TO 64.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 240 PM TUESDAY...
MODELS CONTINUE TO BE DIVERGENT IN THEIR SOLUTIONS WITH THE LOW
PRESSURE SYSTEM FORECAST TO BE IN SOUTHEAST CANADA SATURDAY MORNING.
THE CANADIAN DEVELOPS A COLD AIR DAMMING (CAD) EVENT DURING THE DAY
SATURDAY... PERSISTING THE CAD TO THE END OF ITS MODEL RUN SUNDAY
EVENING. THE CANADIAN SEEMS TO BE AN OUTLIER IN DEVELOPING A
SIGNIFICANT TROUGH AND CUTTING OFF AN UPPER LOW OVER KENTUCKY
SUNDAY. REJECTING THE CANADIAN MODEL AT THIS TIME. IT DOES APPEAR
THE UPPER SYSTEM WILL RETROGRADE SOUTHWEST TOWARD MICHIGAN DURING
THE WEEKEND. THE GFS AND UKMET HAVE TIMING DIFFERENCES BUT ARE
SIMILAR IN DEPICTING A TROUGH OR CUT OFF LOW EXTENDING TOWARD
MISSISSIPPI OR GEORGIA SATURDAY NIGHT INTO SUNDAY.
SHOULD THE APPROACHING UPPER TROUGH OF THE GFS MODEL COME CLOSE TO
VERIFYING... IT WOULD BE REASONABLE TO HAVE AN INCREASED RAIN CHANCE
SUNDAY AFTERNOON... AND HAVE NUDGED POPS TO ONE IN FOUR. CONTINUING
SLIGHT RAIN CHANCES MOST EVERYWHERE OTHERWISE. CONFIDENCE IN THIS
SCENARIO IS QUITE LOW... AND AWAIT FUTURE MODEL RUNS.
TEMPERATURES WILL CONTINUE TO BE FORECAST WITH AN IDEA TOWARD SOUTH
FLOW AND ENOUGH SUNSHINE DURING THE DAY TO KEEP TEMPERATURES NEAR TO
ABOVE NORMAL IN GENERAL. HIGH TEMPERATURES IN THE LOWER 80S
SATURDAY... OTHERWISE 75 TO NEAR 80. LOW TEMPERATURES 59 TO 65.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AS OF 135 PM TUESDAY...
PREDOMINATELY VFR CONDITIONS WILL CONTINUE THROUGH THE TAF
PERIOD...AS HIGH PRESSURE JUST OFF THE VA COAST CONTINUES TO EXTEND
SOUTHWEST ACROSS EASTERN NC. A CLUSTER OF STORMS OVER KY IS
APPROACHING THE VA/NC MOUNTAINS...BUT SHOULD WEAKEN AS IT ENCOUNTERS
THE MOUNTAINS AND A MORE STABLE ENVIRONMENT EAST OF THE
MOUNTAINS..AND ONLY HIGH CLOUDS ARE EXPECTED TO OVERSPREAD KINT/KGSO
THIS EVENING. MEANWHILE...A LIGHT SOUTHERLY TO SOUTHWESTERLY
RETURN FLOW HAS DEVELOPED OVER WESTERN NC...ALLOWING LOW LEVEL
MOISTURE TO SLOWLY RETURN ACROSS THE AREA. A LIGHT WIND OVERNIGHT
SHOULD FEND OFF ANY MORE THAN ISOLATED MVFR VSBYS OVER THE WESTERN
PIEDMONT. FURTHER EAST HOWEVER...KFAY AND KRWI COULD SEE MVFR VSBYS
DEVELOP LATE TONIGHT...MAINLY AFTER 09Z.
AVIATION CONDITIONS ARE EXPECTED TO BE VFR AGAIN ON WEDNESDAY...WITH
A LIGHT SOUTHWESTERLY WIND EXPECTED TO DEVELOP ACROSS ALL OF CENTRAL
NC.
OUTLOOK...
A COLD FRONT IS EXPECTED TO MOVE INTO AND STALL ACROSS MID-ATLANTIC
STATES LATE THIS WEEK. THERE IS SOME UNCERTAINTY AS TO HOW FAR
SOUTH THE FRONT WILL MOVE...WHICH LEADS TO UNCERTAIN IN AVIATION
IMPACTS OVER CENTRAL. AT THIS TIME...MOSTLY VFR CONDITIONS ARE
EXPECTED THROUGH SATURDAY...WITH THE POTENTIAL FOR EARLY MORNING
SUB-VFR CONDITIONS OVER THE WEEKEND.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLS
NEAR TERM...BLS
AVIATION...BLS
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
223 PM EDT TUE SEP 25 2012
.SYNOPSIS...
A WARM FRONT WILL APPROACH FROM THE SOUTHWEST TODAY...BECOMING
STATIONARY THROUGH WEDNESDAY. THIS FRONT WILL BE OVERTAKEN BY A
COLD FRONT DROPPING SOUTH FROM THE GREAT LAKES LATE WEDNESDAY AND
THURSDAY. UNSETTLED WEATHER WILL RESULT UNTIL DRIER AIR WORKS IN
FROM THE NORTH LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AREA OF CONVECTION CONTINUES TO WORK E ACROSS THE REGION. IT IS HOLDING
TOGETHER BETTER ACROSS THE KY COUNTIES. THE LATEST HRRR
RUN...WHICH INITIALIZED PRETTY WELL...TAKES THE SRN PORTION OF THE
SYSTEM THRU THE FA. THE NRN HALF APPEARS TO BE WEAKENING AS IT
COMES IN. THE MATCHES WHAT THE HRRR IS FORECASTING.
LATER THIS AFTN...A WRM FNT LIFTING OUT OF MO...WILL COMBINE WITH
A CDFNT DROPPING SOUTHEAST TO CREATE AN AREA OF LIFT ACROSS THE
MIAMI VALLEY. AS THE LIFT DEVELOPS...CONVECTION WILL DEVELOP MAINLY
ALONG AND NORTH OF I-70.
KEPT HIGHS IN THE UPPER 60S ACROSS THE N...WARMING TO THE MID 70S
ACROSS NRN KY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
LOW LEVEL JET WILL INCREASE IN INTENSITY TONIGHT ALONG THE SLOW
MOVING FRONT WHICH WILL ENHANCE THUNDERSTORM DEVELOPMENT AND
STRENGTH. KEPT POPS AS HIGH AS CATEGORICAL. THERE WILL BE A LOW
CHANCE FOR SEVERE THUNDERSTORMS WITH MARGINAL INSTABILITY THE
LIMITING FACTOR IN A REGIME OF VIGOROUS WIND FIELDS.
SHOWERS AND THUNDERSTORMS WILL CONTINUE TO BE LIKELY ON WEDNESDAY
AS THE FRONT MAKES ITS WAY ACROSS THE AREA. THERE MAY BE A BETTER
CHANCE FOR SEVERE THUNDERSTORMS SINCE INSTABILITY WILL BE
INCREASING IN THE PRESENCE OF PERSISTENTLY STRONG WIND FLOW.
RAINFALL TOTALS FOR THIS EVENT WILL PROBABLY EXCEED AN INCH IN
SOME LOCATIONS.
THE FRONT IS EXPECTED TO BE SITUATED NEAR THE OHIO RIVER WEDNESDAY
NIGHT AND THURSDAY. THIS SCENARIO WILL KEEP A GOOD CHANCE FOR
SHOWERS AND THUNDERSTORMS OVER SOUTHERN COUNTIES DURING THAT
TIME FRAME.
HIGH TEMPERATURES WILL BE NEAR NORMAL...MAINLY IN THE 70S.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
THERE IS UNCERTAINTY WHERE A NEARLY STATIONARY FRONT WILL SET UP.
BUT AT THIS POINT IT APPEARS THAT IT WILL BE CLOSE ENOUGH TO THE
SOUTHERN ZONES TO KEEP A CHANCE OF SHOWERS AND POSSIBLY SOME THUNDER
INTO FRIDAY. EXPECT THE BOUNDARY TO FINALLY GET PUSHED FURTHER
SOUTH AS HIGH PRESSURE BUILDS IN ON THE BACK SIDE OF A DEVELOPING
UPPER LOW. THIS SHOULD SPREAD DRIER AIR ACROSS THE REGION FOR THE
WEEKEND INTO MONDAY. TEMPERATURES WILL BE NEAR NORMAL THROUGH THE
PERIOD.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
MORNING CONVECTION SLID MAINLY S OF THE TAFS...AS THE NORTHERN
PART OF THE SYSTEM FELL APART. BEHIND THE CONVECTION IFR/MVFR CIGS
HAVE WORKED INTO THE TAFS.
THE CIGS ACROSS INDIANA HAVE GRADUALLY RISING AND THE VFR
CONDITIONS SHOULD WORK EWD INTO THE TAFS BY 00Z.
FOCUS NOW SHIFTS TO ANOTHER H5 S/W THAT IS MOVG E THROUGH THE
CONFLUENT FLOW OVER THE OHIO RIVER VALLEY. LOW LEVEL FORCING
INCREASES AFT 21Z OUT AHEAD OF A DIGGING CDFNT. MODELS DEVELOP A
LARGE AREA OF CONVECTION ALONG THE I-70 CORRIDOR. THERE IS SOME
TIMING DIFFERENCES WITH THE ONSET...BUT MOST SUGGEST DEVELOPMENT
AROUND 00Z IN THE W. WENT WITH A PREVAILING MVFR VSBY IN SHRA.
THERE IS INSTABILITY TO WORK WITH...BUT ONLY PUT TS IN A VC GROUP
AT THIS TIME.
AS THE NIGHT PROGRESSES THE FRONT SETTLES TO THE S PUSHING THE
BETTER CONVECTION TOWARDS THE SRN TAFS. A WAVE ON THE FRONT
PUSHES THROUGH AROUND 12Z...PUSHING THE BETTER CHC OF PCPN EWD.
TAPERED THE SHRA TO VC AFTER 12Z...BUT BROUGHT MVFR CIGS IN BEHIND
THE WAVE.
.OUTLOOK...THUNDERSTORMS AND MVFR CONDITIONS POSSIBLE THROUGH
THURSDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...CONIGLIO
NEAR TERM...SITES
SHORT TERM...CONIGLIO
LONG TERM...
AVIATION...SITES
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1231 PM CDT TUE SEP 25 2012
.UPDATE...FOR AVIATION.
&&
.AVIATION...
A FRONT WILL REMAIN STALLED TO OUR NORTH THROUGH THE TAF PD.
ACTIVE SOUTHERN JET WILL TRANSPORT MOISTURE IN THE FORM OF
MID/HIGH LEVEL CLOUDINESS ACROSS THE TAF AREAS. VFR CONDITIONS ARE
EXPECTED WITH SOMETIMES GUSTY SSW WINDS.
13
&&
.PREV DISCUSSION... /ISSUED 1200 PM CDT TUE SEP 25 2012/
DISCUSSION...
HAVE UPDATED THE SUITE OF FORECAST PRODUCTS TO LOWER HIGH TEMPS BY
A COUPLE OF DEGREES ACROSS LOCATIONS W OF THE PLATEAU FOR THIS AFTERNOON
AND TO ADDRESS MOCLDY SKY CONDTIONS ACROSS MOST LOCATIONS FOR THIS
AFTERNOON TOO.
PREV DISCUSSION.../ISSUED 1026 AM CDT TUE SEP 25 2012/
UPDATE...
WITH MOST CONVECTIVE ACTIVITY MOVING W TO OUR N ACROSS CNTRL AND NOW
INTO ERN KY...AND PER REGIONAL SATELLITE...RADAR MOSAICS...AND SFC OBS...
BELIEVE THAT WITH QUASI ZONAL FLOW PATTERN ALOFT...THE MID STATE SHOULD
GENERALLY ONLY EXPERIENCE AN INCREASING CLOUDINESS TREND THRU THE REMAINDER
OF THE MORNING HRS W THRU THE EARLY AFTERNOON HRS E...WITH CLRING POSSIBLE
ACROSS THE ENTIRE MID STATE BY THE LATE AFTERNOON HRS. BEST INSTABILITY
SHOULD REMAIN TO OUR N...AND BELIEVE IF ANY RAINFALL DOES OCCUR...AS 12Z
KOHX SOUNDING SHOWS A CONTINUATION OF THE DRY AIRMASS AT THE SFC...ALONG
WITH CURRENT REGIONAL DEWPOINT DEPRESSION TRENDS WELL OVER 5 DEGREES...THAT
RAINFALL WILL BE ISO AT BEST AND MAY NOT EVEN REACH THE GROUND...AND COULD
EVEN BE MOSTLY SPRINKLE IN NATURE. THRU THE REMAINDER OF THE MORNING HRS HAVE
INTRODUCED A SLIGHT CHANCE FOR LOCATIONS GENERALLY W OF I-65 AND FOR THE
AFTERNOON HRS FOR LOCATIONS E OF I-65. IF CLOUDS DO NOT CLEAR THIS LATE
AFTERNOON AS EXPECTED...MIGHT ALSO HAVE TO LOWER HIGH TEMPS...BUT AT THIS
TIME WILL MONITOR FOR POSSIBLE FUTURE UPDATE.
31
PREV DISCUSSION... /ISSUED 436 AM CDT TUE SEP 25 2012/
SHORT TERM...
THE WARM FRONT THAT WILL INFLUENCE WEATHER FOR MOST OF THE WEEK CONTINUES
TO MOVE NORTHEAST THIS MORNING AND IS CURRENTLY STRETCHING ACROSS THE
MID MISSISSIPPI VALLEY AND OHIO VALLEY. A FEW ASSOCIATED SHOWERS HAVE
BEEN MOVING SLOWLY OVER WESTERN KENTUCKY AND WESTERN TN THIS
MORNING. HRRR SHOWS THIS ACTIVITY PERSISTING AND MOVING INTO MIDDLE
TN LATER THIS MORNING. HOWEVER ANY PRECIP SHOULD REMAIN LIGHT AND
MAINLY IMPACT NORTHWESTERN MIDDLE TN. CLOUD COVER WILL INCREASE
TODAY WITH MAINLY HIGH AND MID CLOUDS MOVING IN AS THE FRONT
REMAINS STATIONARY TUESDAY NIGHT AND WEDNESDAY. DIDN`T VENTURE TOO FAR
FROM GUIDANCE AS FAR AS TEMPS GO. HIGHS WILL BE QUITE A BIT WARMER
TODAY THROUGH THURSDAY...AROUND THE MID 80S AS WE SIT IN THE WARM
SECTOR OF THE FRONT. NIGHT TIME LOWS EXPECTED TO BE IN THE LOW 60S
WITH AREAS ALONG THE PLATEAU IN THE UPPER 50S. BEST PRECIP CHANCES
WILL REMAIN NORTH OF THE MIDSTATE BUT KEPT SLIGHT CHANCE POPS IN
THE PICTURE FOR THE NORTHERN COUNTIES FROM WEDNESDAY MORNING
THROUGH THURSDAY NIGHT.
LONG TERM...
MODELS CAN`T SEEM TO AGREE ON THE MOVEMENT OF THE FRONT TO THE
NORTH. THE NAM BRINGS THE FRONT DOWN TOWARD THE NORTHWESTERN
COUNTIES ON THURSDAY WHILE THE GFS KEEPS THE FRONT TO THE NORTH
OF THE MID- STATE UNTIL FRIDAY NIGHT. LEANED TOWARD THE GFS
SOLUTION, WITH CHANCE POPS MAKING AN APPEARANCE FRIDAY MORNING
ALONG THE NORTHERN PORTION OF OUR AREA AND INCREASING IN COVERAGE
AS SATURDAY APPROACHES. MODELS DO AGREE THAT THIS WEEKEND WILL BE
WET AS AN UPPER TROUGH DEEPENS OVER THE SOUTHEAST WITH THE UPPER
LOW MOVING TO THE WEST OF TN. KEPT CHANCE POPS THROUGHOUT THE
WEEKEND. THEN RAIN CHANCES DECREASES FROM WEST TO EAST AS THE MAIN
MOISTURE AXIS MOVES SLIGHTLY EAST MONDAY. WENT SLIGHTLY COOLER
THAN GUIDANCE ON THE TEMPS IN THE LONG TERM.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS NASHVILLE TN
1200 PM CDT TUE SEP 25 2012
.DISCUSSION...
HAVE UPDATED THE SUITE OF FORECAST PRODUCTS TO LOWER HIGH TEMPS BY
A COUPLE OF DEGREES ACROSS LOCATIONS W OF THE PLATEAU FOR THIS AFTERNOON
AND TO ADDRESS MOCLDY SKY CONDTIONS ACROSS MOST LOCATIONS FOR THIS
AFTERNOON TOO.
&&
.PREV DISCUSSION.../ISSUED 1026 AM CDT TUE SEP 25 2012/
UPDATE...
WITH MOST CONVECTIVE ACTIVITY MOVING W TO OUR N ACROSS CNTRL AND NOW
INTO ERN KY...AND PER REGIONAL SATELLITE...RADAR MOSAICS...AND SFC OBS...
BELIEVE THAT WITH QUASI ZONAL FLOW PATTERN ALOFT...THE MID STATE SHOULD
GENERALLY ONLY EXPERIENCE AN INCREASING CLOUDINESS TREND THRU THE REMAINDER
OF THE MORNING HRS W THRU THE EARLY AFTERNOON HRS E...WITH CLRING POSSIBLE
ACROSS THE ENTIRE MID STATE BY THE LATE AFTERNOON HRS. BEST INSTABILITY
SHOULD REMAIN TO OUR N...AND BELIEVE IF ANY RAINFALL DOES OCCUR...AS 12Z
KOHX SOUNDING SHOWS A CONTINUATION OF THE DRY AIRMASS AT THE SFC...ALONG
WITH CURRENT REGIONAL DEWPOINT DEPRESSION TRENDS WELL OVER 5 DEGREES...THAT
RAINFALL WILL BE ISO AT BEST AND MAY NOT EVEN REACH THE GROUND...AND COULD
EVEN BE MOSTLY SPRINKLE IN NATURE. THRU THE REMAINDER OF THE MORNING HRS HAVE
INTRODUCED A SLIGHT CHANCE FOR LOCATIONS GENERALLY W OF I-65 AND FOR THE
AFTERNOON HRS FOR LOCATIONS E OF I-65. IF CLOUDS DO NOT CLEAR THIS LATE
AFTERNOON AS EXPECTED...MIGHT ALSO HAVE TO LOWER HIGH TEMPS...BUT AT THIS
TIME WILL MONITOR FOR POSSIBLE FUTURE UPDATE.
PREV DISCUSSION.../ISSUED 535 AM CDT TUE SEP 25 2012/
AVIATION 12Z DISCUSSION...
COLD FRONT WILL REMAIN STALLED TO OUR NORTH THROUGH THE TAF PD.
ACTIVE SOUTHERN JET WILL TRANSPORT MOISTURE IN THE FORM OF
MID/HIGH LEVEL CLOUDINESS ACROSS THE TAF AREAS. OTW...VSBYS NOT
EXPECTED TO BE A PROBLEM AS TD DEPRESSIONS TO REMAIN ELEVATED
THROUGH 12Z WED.
PREV DISCUSSION... /ISSUED 436 AM CDT TUE SEP 25 2012/
SHORT TERM...
THE WARM FRONT THAT WILL INFLUENCE WEATHER FOR MOST OF THE WEEK CONTINUES
TO MOVE NORTHEAST THIS MORNING AND IS CURRENTLY STRETCHING ACROSS THE
MID MISSISSIPPI VALLEY AND OHIO VALLEY. A FEW ASSOCIATED SHOWERS HAVE
BEEN MOVING SLOWLY OVER WESTERN KENTUCKY AND WESTERN TN THIS
MORNING. HRRR SHOWS THIS ACTIVITY PERSISTING AND MOVING INTO MIDDLE
TN LATER THIS MORNING. HOWEVER ANY PRECIP SHOULD REMAIN LIGHT AND
MAINLY IMPACT NORTHWESTERN MIDDLE TN. CLOUD COVER WILL INCREASE
TODAY WITH MAINLY HIGH AND MID CLOUDS MOVING IN AS THE FRONT
REMAINS STATIONARY TUESDAY NIGHT AND WEDNESDAY. DIDN`T VENTURE TOO FAR
FROM GUIDANCE AS FAR AS TEMPS GO. HIGHS WILL BE QUITE A BIT WARMER
TODAY THROUGH THURSDAY...AROUND THE MID 80S AS WE SIT IN THE WARM
SECTOR OF THE FRONT. NIGHT TIME LOWS EXPECTED TO BE IN THE LOW 60S
WITH AREAS ALONG THE PLATEAU IN THE UPPER 50S. BEST PRECIP CHANCES
WILL REMAIN NORTH OF THE MIDSTATE BUT KEPT SLIGHT CHANCE POPS IN
THE PICTURE FOR THE NORTHERN COUNTIES FROM WEDNESDAY MORNING
THROUGH THURSDAY NIGHT.
LONG TERM...
MODELS CAN`T SEEM TO AGREE ON THE MOVEMENT OF THE FRONT TO THE
NORTH. THE NAM BRINGS THE FRONT DOWN TOWARD THE NORTHWESTERN
COUNTIES ON THURSDAY WHILE THE GFS KEEPS THE FRONT TO THE NORTH
OF THE MID- STATE UNTIL FRIDAY NIGHT. LEANED TOWARD THE GFS
SOLUTION, WITH CHANCE POPS MAKING AN APPEARANCE FRIDAY MORNING
ALONG THE NORTHERN PORTION OF OUR AREA AND INCREASING IN COVERAGE
AS SATURDAY APPROACHES. MODELS DO AGREE THAT THIS WEEKEND WILL BE
WET AS AN UPPER TROUGH DEEPENS OVER THE SOUTHEAST WITH THE UPPER
LOW MOVING TO THE WEST OF TN. KEPT CHANCE POPS THROUGHOUT THE
WEEKEND. THEN RAIN CHANCES DECREASES FROM WEST TO EAST AS THE MAIN
MOISTURE AXIS MOVES SLIGHTLY EAST MONDAY. WENT SLIGHTLY COOLER
THAN GUIDANCE ON THE TEMPS IN THE LONG TERM.
&&
.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE 82 60 89 61 / 20 10 10 10
CLARKSVILLE 83 59 87 59 / 20 10 20 20
CROSSVILLE 76 56 81 57 / 20 10 10 10
COLUMBIA 83 60 88 60 / 20 10 10 10
LAWRENCEBURG 82 58 87 58 / 20 05 10 10
WAVERLY 84 60 88 59 / 20 10 10 20
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
31
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
223 PM CDT TUE SEP 25 2012
.SHORT TERM...TONIGHT AND WEDNESDAY
HIGH PRESSURE WAS BUILDING INTO WISCONSIN THIS AFTERNOON OUT OF
CANADA...RESULTING IN QUIET WEATHER. JUST A FEW FAIR WEATHER CU
DEVELOPED OVER NORTHERN WISCONSIN AND ALONG WITH LAKESHORE. THIS
AREA OF HIGH PRESSURE WILL CONTINUE TO PUSH INTO NORTHEAST WI
DURING THE SHORT TERM...WITH THE MAIN FORECAST CHALLENGES BEING
CLOUDS AND TEMPERATURES.
A 500MB SHORTWAVE WILL PASS OVER LAKE SUPERIOR OVERNIGHT INTO
WEDNESDAY...BRUSHING NORTHERN WISCONSIN AS IT DOES SO. WITH SFC
HIGH PRESSURE MOVING OVER WISCONSIN...DRY AIR AND A LACK OF
FORCING WILL PREVENT ANY PRECIP SO KEPT DRY FORECAST GOING.
MODELS HAVE BEEN STRUGGLING WITH CLOUDS WITH THIS FEATURE AS IT
MOVES THROUGH. CURRENT SAT ELITE AND RAP MODEL ANALYSIS SHOWS THAT
MOST OF THE MOISTURE ASSOCIATED WITH THE CLOUDS CURRENTLY IN
NORTHEAST MINNESOTA NEAR THE DIGGING SHORTWAVE IS CONFINED TO 925
AND 850MB...SO USED THIS INFORMATION FOR CLOUD FORECAST FOR
TONIGHT AND WEDNESDAY. CU FROM THIS AFTERNOON WILL DISSIPATE WITH
THE SUNSET OVER NORTHERN WI...BUT WILL LINGER NEAR THE LAKESHORE
WITH THE CONTINUED NE FLOW. THE NEXT AREA OF CLOUDS WILL MOVE INTO
NORTHERN WISCONSIN AFTER 06Z TONIGHT. CLOUDS WILL BE LIMITED AT
FIRST...BUT THEN SHOULD INCREASE IN COVERAGE TOMORROW...ESPECIALLY
DURING THE AFTERNOON...AS SUN AIDS IN CU DEVELOPMENT AND
SUFFICIENT 850MB MOISTURE OVERSPREADS THE AREA. NORTHERN WISCONSIN
SHOULD SEE THE MOST CLOUDS AS IT IS NEAREST TO THE PASSING
SHORTWAVE...WITH A MIX OF SUN AND CLOUDS ELSEWHERE.
DIDNT CHANGE MUCH TEMPERATURE-WISE FROM PREVIOUS FORECAST AS
NORTHWEST FLOW WILL KEEP THINGS COOLER THAN NORMAL ON WEDNESDAY.
WIDESPREAD FROST IS AGAIN EXPECTED IN NORTHERN WI WHERE GROWING
SEASON HAS ENDED. PATCHY FROST IS POSSIBLE IN CENTRAL WISCONSIN
TONIGHT...HOWEVER THINK TEMPS WILL BE SLIGHTLY TOO WARM FOR
WIDESPREAD FROST DEVELOPMENT.
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY.
QUIET WEATHER PATTERN EXPECTED THROUGH THE PERIOD. MODELS CONTINUE
TO STRUGGLE WITH CLOSED UPPER LOW ACROSS THE EASTERN UNITED STATES
OVER THE WEEKEND. LATEST GFS IS FURTHER WEST THAN THE CANADIAN AND
THE 12Z LOW RES ECMWF IS FURTHER WEST THAN BOTH THE CANADIAN/GFS.
DID NOT RECEIVE THE 12Z HIGH ECMWF...THEREFORE WILL CONTINUE WITH A
DRY AND CLEAR TO PARTLY CLOUDY FORECAST FOR THE WEEKEND. IF ECMWF
TREND IS CORRECT...LATER SHIFT MAY NEED TO ADD MORE CLOUDS AND
MAYBE A SMALL CHANCE OF SHOWER OVER THE WEEKEND WITH ENERGY
PIVOTING AROUND THE UPPER LOW.
OTHERWISE...IT WILL BE SEASONABLE WITH LOWS IN THE 30S TO LOWER
TO MIDDLE 40S AND HIGHS IN THE 60S TO AROUND 70. DID LOWER MIN
TEMPERATURES A FEW DEGREES EACH NIGHT THROUGH THE WEEKEND...
ESPECIALLY IN THE TYPICAL COLD SPOTS NORTH AND WEST OF GREEN BAY
AND THE FOX CITES. ALSO RAISED MAX TEMPERATURES A FEW DEGREES ON
FRIDAY BASED ON 925MB TEMPERATURES AND EXPECTED DRY AIR MASS IN
PLACE.
&&
.AVIATION...VFR CONDITIONS WILL DOMINATED MOST OF THE REGION
TODAY INTO WEDNESDAY. PATCHY MVFR CIGS MAY PASS OVER PARTS OF
NORTHERN WISCONSIN TONIGHT INTO WEDNESDAY AS A WEAK SHORTWAVE
MOVES OVER LAKE SUPERIOR.
WOLF
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WOLF/ECKBERG