FXUS63 KPAH 090549
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
1150 PM CST WED FEB 8 2012

.UPDATE...
UPDATED AVIATION SECTION. NO UPDATE TO PUBLIC SECTION.

&&

.SHORT TERM.../TONIGHT THROUGH FRIDAY NIGHT/...

LOW CLOUDS WILL SLOWLY DECREASE TONIGHT INTO THURSDAY AS SURFACE
HIGH PRESSURE BUILDS INTO THE MIDDLE MISSISSIPPI VALLEY.
TEMPERATURES WILL MODERATE TO NEAR SEASONAL READINGS.  MID AND HIGH
CLOUDS WILL INCREASE LATE THURSDAY INTO THURSDAY NIGHT AS AN UPPER
LEVEL TROF MOVES ACROSS THE REGION.

GFS...NAM AND ECMWF ALL SHOW A LOW PRESSURE SYSTEM OVER
NORTHERN/CENTRAL TEXAS AT 12Z FRIDAY.  AS THIS LOW MOVES EAST AND A
WEAK COLD FRONT MOVES ACROSS THE REGION...ALL MODELS GENERATE SOME
LIGHT QPF ACROSS THE PAH FORECAST AREA ON FRIDAY.  CONTINUED WITH
SLIGHT TO LOW CHANCE POPS FOR SHOWERS ACROSS OUR REGION...WITH THE
SLIGHTLY BETTER CHANCES ACROSS OUR SOUTHEAST COUNTIES.  NAM AND GFS
ARE FASTER WITH THIS WEATHER SYSTEM...LINGERING SOME LIGHT
PRECIPITATION ACROSS JUST OUR FAR EASTERN COUNTIES INTO EARLY FRIDAY
EVENING.  ECMWF KEEPS SOME LIGHT QPF ACROSS ALL BUT OUR FAR WESTERN
COUNTIES FRIDAY EVENING.  TIMING WILL BE VERY IMPORTANT...WITH
TEMPERATURES DROPPING INTO THE LOWER TO MIDDLE 20S FRIDAY NIGHT.
WITH AN EARLY ENOUGH DEPARTURE OF PRECIPITATION...TEMPERATURES
SHOULD BE WARM ENOUGH TO PREVENT ANY CONCERNS FOR FREEZING OR FROZEN
PRECIP.  WENT WITH THE FASTER GFS/NAM SOLUTION...AND JUST KEPT SOME
SLIGHT TO LOW CHANCE POPS FOR RAIN SHOWERS ACROSS THE SOUTHEAST HALF
OF THE PAH FA FRIDAY EVENING.

.LONG TERM /SATURDAY THROUGH NEXT WEDNESDAY NIGHT/...

THERE ARE SUBTLE MODEL DIFFERENCES IN THE DEGREE OF NAO INFLUENCE
FOR TEMPERATURES THIS WEEKEND AND INTO EARLY NEXT WEEK WITH THE
ECMWF...GFS AND OTHER GUIDANCE. THE ESRL/PSD ENSEMBLE FORECAST STILL
SHOWS A SLIGHTLY STRONGER NAO SIGNAL ON MONDAY /FEB. 13/ THAN THE
ECWMF...BUT CLOSER TO THE GFS. THERE COULD STILL BE THE POTENTIAL
FOR THERMAL PROFILES COLD ENOUGH FOR MIXED PRECIPITATION EARLIER IN
THE DAY. HOWEVER...THE DETERMINISTIC 00Z/12Z RUNS OF THE ECMWF THE
LAST TWO DAYS HAS BEEN INITIALIZING COLDER AND FURTHER WEST THAN THE
12Z DAILY MODEL RUNS OF THE DETERMINISTIC GFS WITH RESPECT TO ACTUAL
UPPER AIR DATA...INCLUDING TODAY. THE INCLINATION IS TO GO WITH THE
GFS/GFS ENSEMBLE SCENARIO FOR THE VERTICAL THERMAL STRUCTURE
/SOUNDINGS/ ON MONDAY. DEPENDING THE ON THE FINAL FORECAST
SURFACE-BASED TEMPERATURES AND DEWPOINTS...THE ZONE OF MIXED
PRECIPITATION POTENTIAL MAY HAVE TO BE ADJUSTED EVEN MORE.

THE OVERALL NCEP PREDICTABILITY FOR THE PERIOD FROM FEBRUARY 11TH
THROUGH 16TH REMAINS MARGINAL /LESS THAN 50 PERCENT/. THE BEST NCEP
ENSEMBLE PROBABILITIES OF 0.1-0.25 INCHES OF PRECIPITATION STILL
RESIDE IN THE 6 AM CST MONDAY TO 6 AM CST TUESDAY TIME FRAME.
DESPITE THE MARGINAL PREDICTABILITY...THE DETERMINISTIC GUIDANCE
SIGNALS REMAIN STRONG FOR AT LEAST SOME PRECIPITATION ON MONDAY INTO
MONDAY NIGHT.

MINOR UPPER LEVEL RIDGING TAKES PLACE TUESDAY...SO REDUCED POPS
SLIGHTLY...ESPECIALLY DURING THE AFTERNOON.

THERE IS SOME DIFFERENCE IN THE TIMING AND INTENSITY OF THE TROUGH
/OR CLOSED LOW BASED ON THE DETERMINISTIC GFS AND ECMWF/ MOVING
OUT OF THE CENTRAL PLAINS NEXT WEDNESDAY. IN COLLABORATION WITH
SURROUNDING NWS OFFICES...DECIDED TO KEEP MOST RAIN IN THE CHANCE
CATEGORY FOR WEDNESDAY.

&&

.AVIATION...
WITH NEAR-ZONAL MID LEVEL FLOW AND THE CENTER OF HIGH SFC PRESSURE
OVER THE REGION FOR NEARLY ALL OF THE NEXT 24 HOURS...EXPECT LIGHT
NRLY/NWRLY SFC WINDS TO SWITCH TO WRLY/SWRLY IN THE MORNING. WINDS A
FEW THOUSAND FEET UP APPEAR LIGHT ALSO...WHICH IS NOT CONDUCIVE TO
MOVING DRIER AIR IN TO REPLACE THE CLOUD DECK OVER THE REGION. THE
MAIN CHALLENGE FOR THIS AVIATION FORECAST HAS BEEN THE PREDICTION OF
CLOUD COVER. BEST GUESS WAS MADE WITH SHORT TERM LAMP/RUC DATA. CIGS
ARE CURRENTLY LOW VFR AND SHOULD STAY THAT WAY...BEFORE GIVING WAY
TO HIGHER CLOUDS SOMETIME THU MORNING.

&&

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

$$

AVIATION...DB
SHORT TERM...RST
LONG TERM....SMITH