Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 231730 AAA
AFDPAH

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PADUCAH KY
1230 PM CDT MON MAR 23 2015

.UPDATE...
ISSUED AT 1221 PM CDT MON MAR 23 2015

THE AVIATION SECTION HAS BEEN UPDATED FOR THE 18Z TAF ISSUANCE.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 348 AM CDT MON MAR 23 2015

THE WEAK SURFACE LOW OVER NORTHWEST MISSOURI AS OF 08Z WILL INDUCE
A SOUTHWEST WIND THROUGHOUT THE AREA TODAY. THIS WILL RESULT IN
MOIST ADVECTION ACROSS THE AREA. TEMPERATURES WILL BE WARMER OVER
THE SOUTHWEST HALF OF THE AREA...BUT INCREASING CLOUDS THIS
AFTERNOON COULD HOLD TEMPERATURES DOWN FROM YESTERDAYS LEVELS IN
THE NORTH AND NORTHEAST. DEFINITELY LEANED TOWARD THE WARM SIDE OF
GUIDANCE. CANNOT RULE OUT A FEW WEAKENING SHOWERS REACHING THE
I-64 CORRIDOR THIS AFTERNOON...BUT MEASURABLE RAINFALL WILL BE
HARD TO COME BY.

MOST OF THE 00Z GUIDANCE...EXCEPT FOR THE ECMWF...CONTINUES TO
TREND DRY ACROSS MOST OF THE AREA TONIGHT AND EVEN TUESDAY. LOOKS
LIKE THE BEST CHANCES OF PRECIPITATION WILL BE TOWARD MIDDAY
TUESDAY ALONG THE I-64 CORRIDOR. HAVE A 50 PERCENT CHANCE IN THAT
AREA TO BLEND WITH OUR NEIGHBORS...BUT WOULD PREFER TO HAVE
LESSER CHANCES. WAS ABLE TO KEEP TONIGHT DRY WITH THE EXCEPTION
OF THE DU QUOIN TO MT VERNON ILLINOIS REGION WHERE SLIGHT CHANCES
ARE IN TO MATCH NEIGHBORING FORECASTS. LEANED TOWARD THE WARM SIDE
OF GUIDANCE FOR LOWS TONIGHT...AND WENT ABOVE GUIDANCE FOR HIGHS
TUESDAY...FIGURING ON LITTLE PRECIPITATION AND INCREASING SOUTHERLY
FLOW.

00Z GUIDANCE IS IN PRETTY GOOD AGREEMENT IN PUSHING A COMPACT
STORM SYSTEM FROM THE CENTRAL PLAINS TOWARD LAKE MICHIGAN TUESDAY
NIGHT. THIS PUSHES AN AREA/LINE OF SHOWERS WITH EMBEDDED THUNDERSTORMS
EASTWARD INTO SOUTHEAST MISSOURI AND SOUTHERN ILLINOIS TUESDAY
EVENING...AND THROUGH THE REMAINDER OF THE AREA OVERNIGHT. HAVE
50-60 PERCENT POPS THROUGHOUT THE AREA TUESDAY NIGHT.

THIS SYSTEM BASICALLY PICKS UP THE WARM FRONT AND PUSHES IT WELL
NORTHEAST OF THE AREA. GIVEN THE IMPRESSIVE FORCING AND VERY MEAGER
INSTABILITY...A MAJOR BOUT OF SEVERE WEATHER IS NOT LIKELY.
HOWEVER...GIVEN THE STRONG UNIDIRECTIONAL WIND FIELDS...WOULD NOT
RULE OUT ISOLATED POCKETS OF DAMAGING WINDS FROM SOUTHEAST
MISSOURI THROUGH SOUTHERN ILLINOIS AND EVEN SOUTHWEST INDIANA.
WIND DAMAGE WOULD BE MOST LIKELY WHERE LINE SEGMENTS CAN GET
ORGANIZED. IT SHOULD BE A MILD NIGHT AS WELL. THE 00Z GUIDANCE IS
IN LINE WITH THE PREVIOUS FORECAST...SO DID NOT MAKE ANY
NOTEWORTHY CHANGES.

THE ATMOSPHERE WILL BE RELAXING IN THE WAKE OF THIS LEAD STORM
SYSTEM WEDNESDAY MORNING...AND THEN RELOADING WEDNESDAY AFTERNOON.
LOW-LEVEL WINDS WILL VEER AND WEAKEN SUBSTANTIALLY BY 12Z
WEDNESDAY...BUT AS THE NEXT SYSTEM APPROACHES...SOUTH WINDS AND
LOW-LEVEL MOISTURE WILL BE ON THE INCREASE IN THE AFTERNOON.
TEMPERATURES SHOULD BE QUITE MILD...GUIDANCE HAS IT WELL IN HAND.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY NIGHT)
ISSUED AT 348 AM CDT MON MAR 23 2015

THE TRANSITION TO THE EXTENDED FORECAST PERIOD ACTUALLY SPLITS THE
MOVEMENT OF THE COLD FRONT AND THE ASSOCIATED CONVECTION THROUGH THE
WFO PAH FORECAST AREA, RELATIVELY SPEAKING.

COMPARED TO THE LAST 4 TO 5 00Z NUMERICAL MODEL RUNS, IT WAS
INTERESTING TO SEE THE TIMING OF THE FRONTAL PASSAGE SLOWED DOWN
WITH THE CURRENT MODEL RUN VERSUS THE PREVIOUS RUNS. THIS MAY BE DUE
TO BETTER SAMPLING AND BOUNDARY INITIALIZATION, BUT NOT SURE AT THE
MOMENT.  HOWEVER, STILL SEE THE LEADING EDGE OF ORGANIZED/SEVERE
CONVECTION MOVING INTO THE SOUTHEAST MISSOURI FOOTHILLS/SOUTHWEST
ILLINOIS IN THE 22Z WED-02Z THU TIME FRAME.  LOOKING AT THE  LATEST
INSTABILITY FIELDS IN THE 0-1KM, 0-3KM, 0-6KM IT SEEMS THAT THE MOST
CAPE EXPENDITURE WILL OCCUR OVER SOUTHEAST MISSOURI AND THE
SOUTHWEST PART OF ILLINOIS, AT LEAST FOR ORGANIZED AND SUSTAINED
UPDRAFTS CAPABLE OF PRODUCING HAIL.  THE LAPSE RATES ACROSS SEGMENTS
OF THE ATMOSPHERE FROM THE SURFACE THROUGH 500 MB, APPEAR TO LIMIT
DAMAGING WIND POTENTIAL (OR AT LEAST MAKE IT MORE ISOLATED) IN THE
00Z-03Z THURSDAY TIME FRAME THE CLOSER YOU GET TO THE OHIO RIVER.
THE BEST SHEAR IN THE 0-3/0-6KM RANGE REMAINS FOCUSED OVER SOUTHEAST
MISSOURI AND SOUTHERN ILLINOIS IN THE 00Z-06Z THURSDAY TIME FRAME.

AT THIS POINT, ANTICIPATE ANY MEANINGFUL SEVERE POTENTIAL WILL BE
LIMITED TO ROUGHLY AT 22Z WED-04Z THURSDAY TIME FRAME AND MAINLY
OVER SOUTHEAST MISSOURI, WITH SOME EXTENSION INTO SOUTHWEST
ILLINOIS. THE EVENT SHOULD TRANSITION INTO A MORE LOCALLY HEAVY RAIN
EVENT AFTER MIDNIGHT OVER WEST KENTUCKY/SOUTHWEST INDIANA. BY 06Z
THURSDAY...LESS OF A SEVERE THREAT WILL BE LIKELY EAST OF A NEW
MADRID MISSOURI TO OWENSBORO KENTUCKY LINE...WITH THE MAIN FOCUS ON
LOCALLY HEAVY RAIN.

FOR THE REST OF THE FORECAST, THE TRANSITION TO DRIER WEATHER WILL
BE ELUSIVE UNTIL THE MAIN TROUGH MOVES EAST OF THE AREA ON FRIDAY.
THE STRONGER AND DEEPER NATURE OF THE TROUGH IS CREATING A MORE
ROBUST INFLUX OF COLDER AIR THAN IN PREVIOUS MODEL RUNS, SO MAX/MIN
TEMPERATURES ARE TRENDING DOWNWARD. THIS WAS HINTED AT BY THE ECMWF
AND ENSEMBLES WITHIN THE LAST 24 HOURS.

OF LAST NOTE, THE GFS WAS HINTING AT AN INTENSE SURFACE LOW OVER
SOUTHEAST MISSOURI ON APRIL 1ST (NEARLY 10 DAYS OUT). HOPE THIS IS
AN APRIL FOOL`S JOKE...OR IT WILL BE BUSY THAT EVENING.

&&

.AVIATION...
ISSUED AT 1221 PM CDT MON MAR 23 2015

A QUASI-STATIONARY FRONTAL BOUNDARY IS FORECAST TO WAFFLE BACK AND
FORTH ACROSS THE TAF SITES THROUGH THE PERIOD. VFR CONDITIONS ARE
EXPECTED TO PREVAIL AT KCGI/KPAH THROUGH THE PERIOD BUT WITH
MOISTURE POOLING IN THE VICINITY OF THE BOUNDARY...LOW CLOUD COVER
WILL INCREASE. TOWARD THE END OF THE PERIOD COULD SEE MVFR CIGS
WITH VCSH AT KEVV/KOWB. DEPENDING ON THE EXACT LOCATION OF THE
FRONT AT ANY GIVEN TIME, WINDS WILL BE VARIABLE BUT SHOULD REMAIN
BELOW 10 KNOTS.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&

$$

SHORT TERM...DRS
LONG TERM...SMITH
AVIATION...JP


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