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000
FXUS63 KPAH 210726
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
226 AM CDT TUE MAY 21 2013

.SHORT TERM...(TODAY THROUGH THURSDAY NIGHT)
ISSUED AT 215 AM CDT TUE MAY 21 2013

NEAREST TERM IS DEALING WITH REMAINING CONVECTION/TOR WATCH BOX.
IN GENERAL...THE TREND IS DIMINISHING IN STRENGTH/INTENSITY AS THE
LINE SINKS SOUTHWARD AND EASTWARD. A FEW HEALTHY CELLS MAY
CONTINUE TO PULSE...HOWEVER...AND WITH A COUPLE OF OUTFLOW
BOUNDARIES WORKING OUT OF THE NORTHERN AND SOUTHERN PORTIONS OF
THE CONVECTIVE LINE...WE`LL ONLY DROP WATCH BOX COUNTIES BEHIND
THE LINE.

THE MODELS SHOW THE CONVECTION MOVING EAST...WEAKENING...AND THEN
REFIRING THIS PM/EVENING AS THE UPPER LEVEL JET ENTERS THE
PICTURE. BEST LIFT/INSTABILITY WILL BE TO OUR SOUTH...BUT A SLGT
RISK OF SVR WILL CONTINUE. WOULD NOT BE SURPRISED TO SEE A PTN OF
THE CWA/ESP SEMO/SWKY/SWIL...INCLUDED IN A LATE DAY-EARLY EVENING
WATCH BOX.

ASSOCIATED SURFACE WAVE OPENS UP AND LIFTS ACROSS MO/IL/IN
TONIGHT. THIS WILL DRIVE THE FRONT AND ASSOCIATED CONVECTION THRU
THE AREA. INSTABILITY LESSENS WITH TIME/OVERNIGHT BUT ACTIVE
CONVECTION EARLY IN THE PERIOD MAY EXTEND THRU THE
NIGHT...SOMETHING TO WATCH AND A HIGH POP/CATEGORICAL MENTION IS
WARRANTED EITHER WAY.

THE UPPER TROF/BEST HEIGHT FALLS OCCUR WEDNESDAY AND DRIVE THE
SYSTEM THRU/TO THE EAST OF US THRU WEDNESDAY NIGHT. POPS MAY EVEN
LINGER THRU THURSAY AS 2NDARY UPPER TROF PASSAGE ALLOWS SOME
DIURNAL INSTABILITY SHOWERS/STORMS TO DEVELOP...PARTICULARLY NRN/ERN
PTNS FA. THE SYSTEM DEPARTS TO THE EAST BY THU NIGHT...WHEN
PLEASANTLY COOLER/DRIER AIR STARTS TO OVERTAKE THE COLUMN. 80S AND
60S COOL TO 70S AND 50S THEREAFTER.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 126 PM CDT MON MAY 20 2013

AT THE START OF THE EXTENDED PERIOD...THE GFS ENSEMBLE MEAN AND
DETERMINISTIC GFS/ECMWF/GEM GUIDANCE ARE QUITE SIMILAR IN TAKING THE
REMNANTS OF THE CURRENT CLOSED LOW IN THE PLAINS AND OPENING IT UP
AS A PROGRESSIVE/POSITIVE TILT SHORTWAVE ALONG THE WESTERN GREAT
LAKES...THEN MOVING THIS WAVE INTO THE NEW ENGLAND STATES BY THE
WEEKEND. A BROAD RIDGE THEN DEVELOPS BEHIND THE SHORTWAVE THURSDAY
NIGHT AND STRONGLY PERSISTS THROUGH SATURDAY NIGHT. FROM SUNDAY
INTO MONDAY...SMALL DIURNAL CHANCES FOR MAINLY AFTERNOON
CONVECTIVE ACTIVITY WILL BE POSSIBLE...ASSOCIATED WITH
MINOR/MESOSCALE IMPULSES MOVING THROUGH THE RIDGE IMPACTING THE
LAPSE RATES ON A SMALLER SCALE. THE LATE WEEKEND/EARLY NEXT WEEK
POPS/WEATHER ARE ACTUALLY LOWERED SLIGHTLY FROM THE PREVIOUS
FORECAST PACKAGE.

GIVEN THE NUMERICAL MODEL GUIDANCE UTILIZED TOWARD THIS
FORECAST...MADE SOME UPWARD ADJUSTMENTS ON MAX/MIN TEMPERATURES AND
LOWERED DEWPOINT GUIDANCE TO ACCOUNT FOR MODEL BIASES. IN
ADDITION...HAD TO VEER SURFACE WINDS SLIGHTLY TO COUNT FOR
INITIALIZATION ISSUES.

&&

.AVIATION...
ISSUED AT 215 AM CDT TUE MAY 21 2013

ACTIVE ONGOING CONVECTION AT THIS WRITING. GUST FRONTS PRODUCING
WINDS/GUSTS TO 35 KTS PRECEDE MAIN LINE OF CONVECTION ROUGHLY 30-60
MINUTES WHERE STORM GUSTS MAY LIKEWISE REACH 35 KTS OR BETTER.
EXPECT MOST INTENSE ACTIVITY NEXT 2-3 HOURS TO THEN DETERIORATE TO
MORE MODERATE SHOWER ACTIVITY WITH MVFR CONDITIONS IMPROVING TO
VFR BY MID MORNING. PM REDEVELOPMENT WILL HAVE HIGHEST POPS WEST
TO LOWEST EAST...WITH RETURN TO MVFR CONDTIONS BY EVENING
EXPECTED AS ANOTHER ROUND HITS TERMINALS/FLIGHT PATHS. IN BOTH
INSTANCES A STRONG STORM MAY PRODUCE IFR CIGS/VSBYS ALBEIT SHORT-
LIVED.

&&

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

$$