Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 262331
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
631 PM EST FRI DEC 26 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 328 PM EST FRI DEC 26 2014

MODELS ARE IN GOOD AGREEMENT THROUGH THE SHORT TERM WILL ONLY SOME
TIMING DIFFERENCES TO DEAL WITH FROM THE HIGHER RESOLUTION 12Z NAM.
BUT 18Z RUN OF THE NAM HAS SLOWED ONSET OF PRECIPITATION INTO THE
AREA LATE SATURDAY...NOW MORE IN LINE WITH THE GFS AND ECMWF.
MID/UPPER LEVEL RIDGE...CENTERED OVER CUBA HAS AMPLIFIED SLIGHTLY
OVER THE CENTRAL AND SOUTHERN APPALACHIANS DUE TO THE EASTWARD
MOVEMENT OF A TROUGH LIFTING OUT OF THE WESTERN GREAT BASIN...
SOUTHWEST CONUS. AT THE SFC...FAIRLY STATIONARY HIGH PRESSURE WAS
CENTERED OVER THE CENTRAL ATLANTIC COASTAL REGION KEEPING OUR AREA
UNDER THE INFLUENCES OF SOUTHERLY FLOW. STRONG SUBSIDENCE WAS
RESPONSIBLE FOR VERY DRY AIR MIXING INTO THE TOP OF THE BOUNDARY
LAYER EARLIER TODAY BUT DEW POINTS HAVE RECOVERED SOME THIS
AFTERNOON. POSITION OF THIS HIGH AND DRY AIR AT THE SFC WILL BE
FAVORABLE FOR A STRONG RIDGE VALLEY SPLIT ACROSS THE AREA TONIGHT.

CONTINUED MOVEMENT OF MID/UPPER LEVEL TROUGH OUT OF THE WESTERN CONUS
WILL INDUCE A SERIES OF SFC LOWS...THE FIRST DEVELOPING OVER THE
EASTERN PLAINS AND MOVING INTO THE GREAT LAKES BY SATURDAY. THIS
FIRST LOW WILL DRAG A SFC COLD FRONTAL BOUNDARY INTO THE OHIO VALLEY
SATURDAY NIGHT INTO SUNDAY MORNING. A SECOND LOW WILL DEVELOP MUCH
FURTHER SOUTH OVER THE SOUTHERN MISSISSIPPI VALLEY REGION AND TRACK
NORTHEAST ALONG THE FRONT AS IT PUSHES ACROSS THE APPALACHIANS EARLY
SUNDAY MORNING. THIS WILL TEND TO KEEP OUR WEATHER WET THROUGH TO THE
END OF THE SHORT TERM.

FOR SENSIBLE WEATHER...MID AND HIGH LEVEL CLOUDS WILL ENTER OUR AREA
LATE THIS AFTERNOON INTO THIS EVENING...THEN THICKEN AND LOWER WITH
TIME. TIMING THE ONSET OF SHOWER ACTIVITY INTO THE AREA LATE SATURDAY
IS MAIN FORECAST CHALLENGE. BUT A BLEND OF SOLUTIONS SUGGESTS
SCATTERED SHOWERS ENTERING OUR WESTERN MOST COUNTIES LATE SATURDAY
AFTERNOON AND OVERSPREADING THE REST OF OUR FORECAST AREA SATURDAY
NIGHT. INCREASED POPS TO CATEGORICAL LEVELS SATURDAY NIGHT. FOR
TEMPS...WENT COLD IN OUR VALLEYS AREA TONIGHT....ESPECIALLY IN OUR
EAST WHERE SOUTHERLY WINDS WILL NOT BE STRONG TO MIX THE NOCTURNAL
INVERSION OUT. HIGHS SATURDAY WILL RUN 3 TO 5 DEGREES WARMER THAN
TODAY...WITH A RELATIVELY BROKEN SKY COVER TENDING TO KEEP HIGHS DOWN
A BIT. CLOUD COVER AND RAINFALL WILL MODERATE LOWS SATURDAY NIGHT
INTO SUNDAY MORNING...WITH MOST LOCATIONS ONLY DROPPING INTO THE MID
40S.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 407 PM EST FRI DEC 26 2014

THE EXTENDED FORECAST PERIOD BEGINS WITH AN ELONGATED TROUGH MOVING
THROUGH THE MIDWEST AND INTO THE APPALACHIAN CHAIN. THE SOUTHERN
PORTION OF THE TROUGH DEVELOPS A STRONGER SHORTWAVE ALONG THE GULF
COAST AS IT BEGINS TO RIDE TO THE NORTHEAST OVER THE RIDGE LOCATED
IN THE BAHAMAS. AS THIS FEATURE AND ASSOCIATED LONG WAVE TROUGH EXITS
THE EASTERN CONUS...THE UPPER LEVEL PATTERN TRANSITIONS TO A BROAD
TROUGH EXTENDED ENTIRELY ACROSS THE LOWER CONUS WITH A CLOSED LOW
DIVING SOUTH ALONG THE WEST COAST AND INTO THE BAJA REGION. MODELS
STILL HAVE THIS FEATURE EJECTING EASTWARD INTO THE GULF COAST REGION.

AT THE SURFACE...CONCERNING THE SUNDAY THROUGH MONDAY TIME FRAME THE
FRONT WILL BE MOVING THROUGH EASTERN KENTUCKY ON SUNDAY WHILE
SLOWING ALONG THE APPALACHIAN CHAIN. THIS WILL RESULT IN A LONGER
DURATION OF RAINFALL ACROSS THE AREA BEFORE EXITING MONDAY NIGHT.
WHILE SOME COLDER AIR WILL BE FILTERING IN BEHIND THIS FRONT...THERE
MAY BE A FEW LOCATIONS THAT WILL SEE A MIX OR CHANGE OVER TO SOME
SNOW BUT NO ACCUMULATION IS EXPECTED SINCE THE DURATION WILL BE SO
SHORT IF AT ALL. QUITE A COLDER AIR MASS WILL FILTER INTO THE OH
VALLEY TOWARD MID NEXT WEEK. THIS COLDER AIR WILL BE IN PLACE FOR
THE ARRIVAL ON THE NEXT SYSTEM MOVING UP FROM THE SOUTH ON THURSDAY
AND WILL RESULT IN SOME SNOWFALL IN SOUTHEAST KENTUCKY. ANY
ACCUMULATION IS QUITE UNCERTAIN AT THIS POINT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 630 PM EST FRI DEC 26 2014

VFR FLIGHT CONDITIONS CAN BE EXPECTED THROUGH THE FORECAST WINDOW.
HOWEVER...HIGH AND MID LEVEL CLOUDS WILL INCREASE...THICKEN AND LOWER
THROUGH THE PERIOD AS WELL. DO NOT EXPECT ANY SHOWERS IN THE FORECAST
UNTIL LATE SATURDAY EVENING...MOVING INTO THE AREA FROM THE
W/SW. GIVEN THE TIMING SO LATE IN THE FORECAST WINDOW...CHOSE NOT TO
INCLUDE SHOWERS IN THE TAF AT THIS TIME...BUT WILL LIKELY IMPACT KSME
AND KLOZ TO SOME EXTENT DURING THE LAST FEW HOURS OF THE PERIOD.
WINDS WILL BE LESS THAN 10 KTS... AND GENERALLY FROM THE S/SW.

&&

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

$$

SHORT TERM...RAY
LONG TERM...SHALLENBERGER
AVIATION...JMW





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