Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 231159
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
759 AM EDT THU APR 23 2015

.UPDATE...
ISSUED AT 759 AM EDT THU APR 23 2015

WILL BE UPDATING TO BLEND EARLY MORNING OBS INTO THE FORECAST AND
TO REMOVE THE FROST ADVISORY FOR THIS MORNING.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 326 AM EDT THU APR 23 2015

SURFACE HIGH PRESSURE WILL BUILD INTO THE REGION TODAY WITH COOL
AND VERY DRY AIR UNDER NW FLOW ALOFT. A RESPECTABLE PRESSURE
GRADIENT AHEAD OF THE HIGH WILL ALLOW WINDS TO BE GUSTY ONCE
MIXING OCCURS TODAY. AS THE HIGH CENTER APPROACHES AND PASSES OVER
TONIGHT...WINDS WILL DIMINISH. WITH DRY AIR AND CLEAR SKIES...THIS
WILL ALLOW TEMPS TO FALL OFF QUICKLY. THINK THAT MOST AREAS WILL
SEE AT LEAST SOME FROST. IT SHOULD BE EXTENSIVE IN OUR NORMALLY
COLD VALLEYS...WHERE READINGS AT LEAST DOWN TO THE UPPER 20S ARE
EXPECTED. HAVE USED A FROST ADVISORY AREA-WIDE AT THIS
POINT...AND A FREEZE WARNING WAS DISCUSSED. IF THE NEXT SHIFT
FEELS THE NEED...THERE WILL STILL BE TIME TO UPGRADE TO A WARNING.
THE HIGH WILL MOVE TO OUR EAST ON FRIDAY AND WARM AIR ADVECTION
OFF THE GULF OF MEXICO WILL ENSUE. THIS WILL BRING INCREASING
CLOUDS...BUT PRECIP IS QUESTIONABLE...AND IS LIKELY TO HOLD OFF
UNTIL THE LONG TERM PERIOD. THE NAM SHOWS .01-.02 INCHES IN OUR
FAR SW BY 00Z SATURDAY...BUT THE GFS AND ECMWF ARE BOTH DRY. HAVE
USED ONLY A 20 PERCENT POP IN THE FAR SW.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 344 AM EDT THU APR 23 2015

THE MODELS ARE IN PRETTY GOOD AGREEMENT TO BEGIN THE EXTENDED
PERIOD...WITH BOTH THE GFS AND ECMWF DEPICTING A LARGE SCALE
UPPER TROUGH EJECTING OUT OF THE WEST CENTRAL PLAINS AND ACROSS
THE OHIO AND TENNESSEE VALLEY REGIONS SATURDAY AND SUNDAY. THIS
SYSTEM IS POISED TO BRING ANOTHER GOOD SOAKING RAIN EVENT TO
EASTERN KENTUCKY FOR THE UPCOMING WEEKEND. THE LATEST SOUNDINGS
INDICATE THAT THUNDERSTORMS WILL BE POSSIBLE FROM SATURDAY
AFTERNOON THROUGH EARLY SUNDAY MORNING...AS AN AREA OF LOW
PRESSURE MOVES ACROSS KENTUCKY. THE RAIN COULD BE LOCALLY HEAVY AT
TIMES SATURDAY AND SATURDAY NIGHT. AT THIS TIME...THERE IS EVEN AN
OUTSIDE CHANCE THAT A FEW STRONG TO SEVERE STORMS MAY OCCUR ON
SATURDAY ACROSS SOUTHWESTERN AND SOUTHERN PORTIONS OF THE FORECAST
AREA. THERE IS STILL SOME UNCERTAINTY AS TO HOW MUCH INSTABILITY
WILL BE AVAILABLE TO SUPPORT STRONGER STORMS...SO THIS SITUATION
WILL CONTINUE TO BE MONITORED CLOSELY IN THE COMING DAYS.

ONCE THIS INITIAL WEATHER SYSTEM DEPARTS THE REGION ON
SUNDAY...IT DOES APPEAR THAT THERE WILL BE A PERIOD OF QUIET
WEATHER SUNDAY NIGHT THROUGH LATE IN THE DAY ON TUESDAY AS A RIDGE
OF HIGH PRESSURE SETTLES OVER THE AREA. AFTER THAT...HOWEVER...IS
WHEN THE MODELS DIVERGE GREATLY IN THEIR RESPECTIVE SOLUTIONS.
THE ECMWF MODEL KEEPS THE OHIO AND TENNESSEE VALLEYS FREE OF
PRECIPITATION FOR THE REST OF THE WEEK...WHILE THE GFS BRINGS
ANOTHER LARGE AND MOISTURE LADEN WEATHER SYSTEM OUT OF THE
SOUTHERN PLAINS AND ACROSS OUR NECK OF THE WOODS. IN FACT...IF THE
GFS VERIFIES...WE WOULD SEE A PROLONGED PERIOD OF WET WEATHER FROM
LATE TUESDAY THROUGH THURSDAY. WITH ALL THAT BEING SAID...IT DID
NOT MAKE SINCE TO GO ALL IN ON EITHER MODEL SOLUTION...SO A
COMPROMISE WAS MADE. AFTER INGESTING THE MODEL BLEND
DATA...DECIDED TO DECREASE THE RESULTING POPS FOR TUESDAY ONWARD
TO WELL BELOW THE ORIGINAL NUMBERS...GOING WITH GENERAL SLIGHT
CHANCE TO CHANCE PROBABILITIES OF PRECIPITATION FOR THE PERIOD
TUESDAY ONWARD. THIS SECOND AREA OF LOW PRESSURE LOOKS TO LACK
GOOD INSTABILITY...AT LEAST THE GFS VERSION THAT HAS PRECIP...SO
THUNDER WAS LEFT OUT AT THIS TIME WITH THE SECOND WEATHER SYSTEM.

TEMPERATURES DURING THE EXTENDED PERIOD LOOK LIKE THEY WILL BE
SLIGHTLY BELOW NORMAL FOR THE TIME OF YEAR. THE PRIMARY REASONS
FOR THIS WILL BE CLOUD COVER AND PRECIPITATION ASSOCIATED WITH THE
AFOREMENTIONED WEATHER SYSTEMS. HIGHS EACH DAY ARE EXPECTED TO TOP
OUT IN THE 60S...WITH OVERNIGHT LOWS MOSTLY IN THE LOW TO MID 40S.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 726 AM EDT THU APR 23 2015

VFR CONDITIONS WILL PERSIST THROUGH THE PERIOD. THE ONLY CONCERN
WILL BE WINDS. THEY WILL INCREASE FROM THE WEST NORTHWEST DURING
THE DAY...WITH GUST FROM 15-20 KTS. WINDS WILL THEN DIMINISH THIS
EVENING.


&&

.JKL WATCHES/WARNINGS/ADVISORIES...

FROST ADVISORY FROM 1 AM TO 9 AM EDT FRIDAY FOR KYZ044-050>052-
058>060-068-069-079-080-083>088-104-106>120.

&&

$$

UPDATE...HAL
SHORT TERM...HAL
LONG TERM...AR
AVIATION...HAL


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