Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 010255 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
1055 PM EDT TUE MAR 31 2015

.UPDATE...
ISSUED AT 1055 PM EDT TUE MAR 31 2015

THE WINDS ARE STARTING TO SETTLE MORE EFFECTIVELY LATE THIS
EVENING ALONG WITH HIGHER RH LEVELS. ACCORDINGLY HAVE UPDATED THE
HWO TO REMOVE THE FIRE WEATHER CAUTIONS FOR THE EVENING PERIOD.
HAVE ALSO TOUCHED UP THE GRIDS VIA THE INFUSION ON THE LATEST
SHORTBLEND GUIDANCE...OBS...AND TRENDS. THESE UPDATES HAVE BEEN
SENT TO THE NDFD AND WEB SERVERS.

UPDATE ISSUED AT 810 PM EDT TUE MAR 31 2015

23Z SFC ANALYSIS SHOWS A DRY COLD FRONT DROPPING THROUGH EASTERN
KENTUCKY. THIS IS SUPPORTING BREEZY AND DRY CONDITIONS THROUGH THE
AREA THIS EVENING. THIS HAS LED TO SEVERAL WILD FIRES DEVELOPING
THROUGH THE AREA EARLIER IN THE DAY THAT CONTINUE...AS SEEN ON THE
DUAL POL RADAR LOOPS...CC IN PARTICULAR. THE WINDS WILL SLOWLY
SETTLE THROUGH THE REST OF THE EVENING AS THE PRESSURE GRADIENT
RELAXES AND THE MIXING HEIGHTS FALL. ACCORDINGLY...HAVE ALLOWED
THE RED FLAG WARNING AND SPS FOR FIRE WEATHER CONCERNS EXPIRE.
HOWEVER...DID CONTINUE THE CAUTIOUS WORDING IN THE HWO FOR THE
REST OF THE EVENING FOR NEAR CRITICAL CONDITIONS. ALSO FINE TUNED
THE T/TD GRIDS PER THE LATEST SHORTBLEND GUIDANCE...OBS...AND
TRENDS. FINALLY...TOOK SKY COVER DOWN ANOTHER NOTCH WITH THIS
UPDATE. THESE GRIDS HAVE BEEN SENT TO THE NDFD AND WEB SERVERS
WHILE AN UPDATED ZFP AND HWO WERE ISSUED.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 345 EDT TUE MAR 31 2015

CURRENT CONDITIONS ACROSS THE AREA FEATURE MAINLY CLEAR SKIES
WITH A AN UPSTREAM DRY COLD FRONT MOVING SOUTHEAST. AS OF
19Z...THE FRONT IS MOVING ACROSS THE OH RIVER AND INTO EASTERN
KENTUCKY. WITH THIS...A STRONG GRADIENT WILL BE PRESENT WITH SOME
20 TO 25 KNOT GUSTS AND THIS WILL CONTINUE WITH AND BEHIND THE
FRONT. EXPECTING WINDS TO DECREASE AND DECOUPLE BY 23Z THIS
EVENING. PROFILES THIS EVENING CONTINUE WITH A DEEP DRY LAYER AND
WILL KEEP SKIES MOSTLY CLEAR THROUGH TONIGHT AS WELL. WHILE THE
CENTER OF HIGH PRESSURE WILL NOT HAVE MOVED INTO THE AREA...SOME
RIDGE VALLEY SPLIT WILL STILL DEVELOP TONIGHT. THE DRY AIR THIS
EVENING AND GUSTY WINDS WITH THE COLD FRONT WILL ALLOW FOR SOME
HAZARDOUS FIRE WEATHER CONDITIONS AND WILL KEEP THIS IN THE HWO.

HEADING INTO THE DAY ON WEDNESDAY...MID LEVEL RIDGING WILL BE
MOVING INTO THE AREA WITH SURFACE HIGH PRESSURE CENTERED OVER THE
OH VALLEY. WINDS WILL BE LIGHT DURING THIS TIME AND WITH THE
HIGHER SUN ANGLE...TEMPERATURES WILL REBOUND INTO THE MID 60S
DESPITE THE COLD FRONT PASSING THROUGH ON TUESDAY EVENING. STILL A
DRY AIR MASS WILL BE IN PLACE WITH AFTERNOON RELATIVE HUMIDITIES
DROPPING INTO THE LOWER 30 PERCENT RANGE.

FOR WEDNESDAY NIGHT... A STRONG SHORT WAVE MOVES INTO THE MS RIVER
VALLEY AS SOUTHERLY FLOW INCREASES INTO THE TN AND OH VALLEY. A
WEAK DISTURBANCE MOVES NORTHEAST OUT OF THE GULF AND INTO KY
BRINGING A CHANCE FOR SHOWERS INTO EASTERN KENTUCKY BY DAWN ON
THURSDAY. BY DAWN ON THURSDAY...A STRONG COLD FRONT DEVELOPS AS
THIS WAVES MOVES INTO THE MIDWEST. FORCING AND INSTABILITY LOOKS
TO BE STRONG ENOUGH THAT A FEW THUNDERSTORMS MAY MOVE INTO THE
AREA BY DAWN ON THURSDAY. FOR NOW WILL STAY WITH CHANCE SHOWERS AS
THERE WILL BE SOME DRY AIR TO OVERCOME AS WELL.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 357 PM EDT TUE MAR 31 2015

THE OHIO RIVER VALLEY WILL FIND ITSELF IN TRANSITION DURING THE DAY
THURSDAY...AS UPPER LEVEL RIDGING BEGINS TO EXIT...AND A SUBTLE
LONGWAVE TROUGH OVER THE WESTERN HALF OF THE CONUS BEGINS TO SHIFT
EASTWARD. EXPECT THIS LONGWAVE TROUGH TO MAKE IT INTO THE
MISSISSIPPI RIVER VALLEY...AND THEN THEN OHIO RIVER VALLEY BY FRIDAY
EVENING. MEANWHILE...A STRONG SHORTWAVE WILL TRAVERSE SOUTHERN
CANADA JUST AHEAD OF THIS LONGWAVE TROUGH. MODELS ARE IN
SURPRISINGLY GOOD AGREEMENT WITH THESE FEATURES...OTHER THAN A FEW
SLIGHT TIMING DIFFERENCES...AND CONTINUE TO BE SO THROUGHOUT THE
WEEKEND AS THE TROUGH AXIS EXITS. ZONAL FLOW AND GENERAL RIDGING
WILL THEN TAKE HOLD SUNDAY NIGHT THROUGH THE REMAINDER OF THE
FORECAST PERIOD.

TWO SURFACE LOW PRESSURE SYSTEMS WILL SET UP ALONG THE LONGWAVE
TROUGH AND SHORTWAVE AS WE HEAD INTO THE EXTENDED. BY 12Z
THU...EXPECT THESE SURFACE LOW PRESSURE SYSTEMS TO BE
LOCATED...ONE...JUST NORTH OF LAKE SUPERIOR...AND 2...ALONG THE
SOUTHERN PLAINS. AN EXTENSIVE COLD FRONT WILL LINK THESE TWO
SYSTEMS...QUICKLY SWEEPING EASTWARD WITH THE LONGWAVE TROUGH
MOVEMENT.

WITH SOUTHERLY FLOW ALREADY IN PLACE...AND A GOOD PULL OF WARM MOIST
AIR COMING OFF THE GULF OF MEXICO...EXPECT CONVECTION TO BEGIN
DEVELOPING DURING THE DAY ACROSS KY...WELL AHEAD OF THE COLD FRONT.
COVERAGE AND INSTABILITY WILL INCREASE AS THE COLD FRONT NEARS
THURSDAY NIGHT. BY FRIDAY MORNING...THE SOUTHERN-MOST LOW PRESSURE
SYSTEM WILL BE IN MI/AR...AND THE NORTHERN ONE WILL HAVE RACED
FARTHER AHEAD AND NORTHWARD INTO FAR NE CANADA. THE COLD FRONT WILL
BE LOCATED ALONG THE OHIO RIVER AND BECOME NEARLY STATIONARY AS IT
BECOMES FURTHER ELONGATED FROM WEST TO EAST. THIS LARGE AREA OF
FRONTOGENESIS/INSTABILITY WILL INCREASE CONVECTIVE ACTIVITY THURSDAY
NIGHT AND INTO FRIDAY...WITH 6 HOUR PWAT VALUES WELL OVER 1 INCH
THURSDAY AFTERNOON THROUGH FRIDAY MORNING...INCREASING TO OVER 1.25
INCHES DURING THE DAY FRIDAY. AS SUCH...EXPECT FLASH FLOODING TO BE
A CONCERN AS WE HEAD INTO THE DAY FRIDAY...ESPECIALLY UNDER SOME OF
THE LARGER SHOWERS AND THUNDERSTORMS.

FRIDAY EVENING...THE FRONT WILL FINALLY MAKE A VERY QUICK SHIFT
ACROSS KY FRIDAY EVENING...PULLING IN MUCH DRIER AND SOMEWHAT COOLER
NW FLOW. THIS WILL ALSO KICK IN A SUBSIDENCE INVERSION...PREVENTING
ANY FURTHER THUNDERSTORM DEVELOPMENT...AND QUICKLY CUTTING OFF BEST
QPF. EXPECT SHOWERS AND ANY LINGERING THUNDER TO TAPER OFF
OVERNIGHT. ECMWF TRIES TO HOLD ONTO SOME UPSLOPE FLOW THROUGH THE
FIRST HALF OF THE DAY SATURDAY...WHILE THE GFS PULLS THE FRONT FAR
ENOUGH SE THAT THERE IS NO LINGERING MOISTURE INFLUENCE. EXPECT IT
WILL LIKELY BE A COMBINATION OF THESE TWO SOLUTIONS...SO WILL KEEP
WITH A MODEL BLEND OF PRECIP THROUGH THE DAY SATURDAY. ANY
ADDITIONAL ACCUMULATIONS WILL BE VERY LIGHT WITH VERY LITTLE
MOISTURE LEFT IN THE SOUNDINGS.

MORE ZONAL UPPER LEVEL FLOW WILL TAKE HOLD THROUGH THE REMAINDER OF
THE WEEKEND. AFTER A DROP IN TEMPS FROM THE COLD FRONTAL PASSAGE ON
SATURDAY...EXPECT THEM TO SLOWLY MODERATE TO NEAR OR ABOVE NORMAL.
HOWEVER...BOTH THE ECMWF AND GFS ARE TRYING TO DEVELOP A WEAK
FRONTAL BOUNDARY ALONG THIS ZONAL FLOW AS WE HEAD FROM MONDAY INTO
TUESDAY...WITH STRONG SOUTHERLY FLOW AND ABUNDANT MOISTURE FLOWING
INTO THE OHIO RIVER VALLEY OFF OF THE GULF OF MEXICO. IF THIS
CONTINUES TO ORGANIZE...COULD BE LOOKING AT ANOTHER CHANCE FOR RAIN
AND THUNDERSTORMS...THOUGH THERE IS STILL QUITE A BIT OF
DISAGREEMENT ON INTENSITY AND COVERAGE.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 825 PM EDT TUE MAR 31 2015

VFR CONDITIONS WILL CONTINUE THROUGH THE PERIOD. A COLD FRONT IS
MOVING THROUGH THE AREA THIS EVENING WITH WEST TO NORTHWEST WINDS
GUSTING TO BETWEEN 20-25 KTS. THESE WINDS WILL SUBSIDE OVER THE
NEXT COUPLE OF HOURS WITH NO AVN CONCERNS THROUGH THE REMAINDER
OF THE PERIOD AS SKIES REMAIN MAINLY CLEAR AND THE WINDS STAY
LIGHT INTO THE DAY WEDNESDAY.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...GREIF
SHORT TERM...SHALLENBERGER
LONG TERM...JMW
AVIATION...GREIF



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