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000
FXUS63 KPAH 110907
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
407 AM CDT SAT MAY 11 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CDT SAT MAY 11 2013

MAIN FORECAST ISSUES LIE WITH SHOWER/ISOLD THUNDER CHANCES
TODAY/EARLY TONIGHT ALONG A SECONDARY COLD FRONT MOVING SOUTHEAST
INTO THE REGION...THEN WITH FROST CHANCES AND NEAR RECORD COLD
FOLLOWING THE FRONT...ESP SUN NIGHT.

STILL LOOKS LIKE THERE WILL BE JUST ENOUGH LIFT AND MOISTURE IN A
NARROW BAND ALONG A SECONDARY COLD FRONT THAT WILL BE CROSSING THE
REGION THIS AFTERNOON/EARLY EVENING TO PRODUCE SCT SHOWERS AND
POSSIBLY EVEN A FEW ISOLATED STORMS. DECIDED TO LEAVE ONGOING
FORECAST AS IS FOR THE MOST PART AND BRING THIS CHC DOWN TO ABOUT
THE OHIO RIVER LATE IN THE DAY. WILL BE A SMALL AND QUICK MOVING
SYSTEM THOUGH...AND WILL EXIT THE REGION EARLY TONIGHT.

COLD...DRY ADVECTION WILL TAKE OVER TONIGHT AND SUNDAY...THEN
SURFACE HIGH PRESSURE WILL SETTLE IN SUNDAY NIGHT. THIS WILL
RESULT IN EXCELLENT RADIATIONAL COOLING CONDITIONS. MODEL
CONSENSUS CONTS TO TAKE DEWPOINTS INTO THE LOWER AND MIDDLE 30S.
SO...LOWS IN THE 30S AND AT LEAST SOME PATCHY FROST SEEMS TO BE
LIKELY FOR MUCH OF THE AREA. WILL ALSO CHALLENGE RECORD LOW TEMPS
MON MORNING. HIGH TEMPS WILL LIKELY STAY IN THE 60S ON MOTHERS DAY.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 AM CDT SAT MAY 11 2013

HE LONG TERM WILL BE MAINLY DRY AND SOMEWHAT WARMER THAN NORMAL AS
THE 500 MB MEAN RIDGE POSITION SETS UP OVER THE CENTRAL STATES. THE
MAIN EXCEPTION WILL BE THURSDAY...WHEN A WEAKENING TROUGH LIFTS
NORTHEAST OUT OF THE SOUTHERN PLAINS.

AS FAR AS THE DAILY DETAILS...STRONG LOW LEVEL WARM ADVECTION WILL
COMMENCE MONDAY NIGHT AND CONTINUE TUESDAY. THE 850 MB TEMP GRADIENT
WILL BE IMPRESSIVE...WITH A DIFFERENCE OF 12 DEGREES CELSIUS BETWEEN
CENTRAL KY AND CENTRAL MO /PER 00Z ECMWF/ TUESDAY MORNING. THE 00Z
ECMWF BRINGS THE PLUS 20 ISOTHERM ACROSS SOUTHERN ILLINOIS ON
TUESDAY...WHICH WOULD NORMALLY TRANSLATE TO HIGHS AROUND 90.
HOWEVER...GFS MODEL SOUNDINGS INDICATE THERE WILL BE A SUBSIDENCE
INVERSION BASED AROUND 900 MB...SO 850 TEMPS WILL NOT BE REFLECTIVE
OF SURFACE TEMPS. FORECAST HIGHS WILL BE KEPT WITHIN A FEW DEGREES
OF GFS MOS. OTHER THAN SOME HIGH BASED CU NEAR THE TOP OF THE MIXED
LAYER TUES AFTERNOON...MODEL SOUNDINGS INDICATE LITTLE POTENTIAL FOR
CLOUDS OR PRECIP.

WEDNESDAY HAS THE POTENTIAL TO BE THE WARMEST DAY SO FAR THIS
YEAR...BASED ON 850 MB TEMPS AROUND PLUS 15 ATOP STEEPENING LOW
LEVEL LAPSE RATES /AS THE SUBSIDENCE INVERSION DISSIPATES/. THE MAIN
LIMITING FACTOR WILL BE THE POTENTIAL FOR INCREASING HIGH CLOUDS
AHEAD OF THE SOUTHERN PLAINS SHORTWAVE. FORECAST HIGHS WILL BE KEPT
CONSERVATIVELY IN THE LOWER TO MID 80S...CLOSE TO 00Z GFS MOS.

THE SOUTHERN PLAINS SHORTWAVE WILL LIFT NORTHEAST ON
THURSDAY...WEAKENING AS IT MOVES THROUGH THE MEAN RIDGE POSITION.
DESPITE THE WEAKENING TREND...THIS SYSTEM SHOULD GENERATE AT LEAST
SCATTERED SHOWERS AND STORMS IN A SEASONABLY MOIST AND UNSTABLE
ENVIRONMENT. FORECAST GFS PW VALUES ARE AROUND 1.5 INCHES. EXTENSIVE
CLOUDS AND SCATTERED CONVECTION SHOULD KEEP HIGHS FAIRLY CLOSE TO
SEASONAL NORMS...WHICH ARE IN THE MID TO UPPER 70S.

SOME DRYING IS ANTICIPATED ON FRIDAY IN THE WAKE OF THE REMNANTS OF
THE SHORTWAVE. AN ASSOCIATED WEAK SURFACE TROUGH/COLD FRONT IS
FORECAST TO DISSIPATE NEAR OR JUST SOUTH OF THE OHIO VALLEY. A FEW
MORE SHOWERS OR STORMS MAY LINGER FRIDAY NEAR THE DISSIPATING
FRONT...MAINLY PRIOR TO THE ARRIVAL OF DRY AIR IN THE AFTERNOON.
WILL KEEP FORECAST HIGHS A DEGREE OR TWO BELOW GFS MOS...WHICH IS IN
THE LOWER 80S.

&&

.AVIATION...
ISSUED AT 1139 PM CDT FRI MAY 10 2013

25 TO 35 KFT CIGS WILL PREVAIL AT ALL SITES THROUGH 15-16Z...THEN
VFR CONDITIONS THROUGH THE END OF THE PERIOD. NORTHERLY WINDS AOB
10 KTS WILL INCREASE TO 12-14 KTS WITH GUSTS UP TO 2O KTS AFTER A
COLD FRONT PASSES AROUND 00Z. SHOWER/STORM CHCS WILL NOT BE NIL
WITH THIS FRONTAL PASSAGE...BUT APPEAR TOO SMALL TO INCLUDE
EXPLICITLY IN THE TAF PACKAGE RIGHT NOW.


&&

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

$$

SHORT TERM...GM
LONG TERM...MY
AVIATION...JP