FXUS63 KPAH 251158
AFDPAH
AREA FORECAST DISCUSSION ...CORRECTED TIME...
NATIONAL WEATHER SERVICE PADUCAH KY
544 AM CST FRI DEC 25 2009
.UPDATE...
UPDATED AVIATION SECTION FOR 12Z TAF ISSUANCE. THE DISCUSSION
SECTION IS UNCHANGED FROM THE 300 AM ISSUANCE.
&&
.DISCUSSION...
988 MB SURFACE LOW WAS CENTERED JUST WEST OF KSTL AT 06Z. POWERFUL
500 MB SHORTWAVE WAS LIFTING ALMOST DUE NORTH ACROSS EASTERN
ARKANSAS. SATELLITE IMAGERY SUGGESTS A CIRCULATION DEVELOPING WITH
THIS SHORTWAVE. RUC INDICATES THE SYSTEM WILL OCCLUDE OVER IOWA
AROUND 18Z TODAY. THE SYSTEM WILL THEN BEGIN TO FILL AS IT BECOMES
QUASI STATIONARY THROUGH SATURDAY NIGHT. RATHER STRONG MID LEVEL
IMPULSES WILL ROTATE AROUND THE MAIN 500 MB LOW. THESE IMPULSES
COULD BRING SOME FLURRIES OR SNOW SHOWERS AT VARIOUS TIMES...BUT
MOISTURE WILL BE QUITE LIMITED.
IN MORE DETAIL...PRECIP WILL CONTINUE TO DIMINISH FROM THE SOUTHWEST
THIS MORNING AS STRONG MID/UPPER LEVEL DRYING ACCOMPANIES THE
PASSAGE OF THE SHORTWAVE. ONGOING LIGHT SNOW IN SOUTH CENTRAL
MISSOURI AT 08Z WAS EVADING RADAR DETECTION...PROBABLY DUE TO THE
SHALLOW DEPTH OF THE PRECIP LAYER. GIVEN THE SHALLOW NATURE OF THE
PRECIP...THE DENDRITIC GROWTH ZONE /MINUS 8 TO MINUS 15 LAYER/ IS
QUITE DRY AND NOT FAVORABLE FOR CRYSTAL GROWTH. WILL MAINTAIN A FEW
TENTHS OF AN INCH OF SNOW ACCUM IN THE GRIDS FOR PARTS OF SE
MISSOURI AND SW ILLINOIS THIS MORNING. BASED ON BUFKIT DATA...THE
CHANGEOVER SHOULD ROUGHLY CORRELATE WITH THE 35 DEGREE SURFACE
ISOTHERM. THIS WOULD BE AROUND 14Z AT KPAH...SOONER TO THE WEST AND
AS LATE AS 18Z IN THE EAST.
THE WIND ADVISORY WILL BE KEPT UP FOR THE TIME BEING. CRITERIA IS 45
MPH GUSTS...AND THIS IS GOING TO BE TOUGH TO MEET ON A WIDESPREAD
BASIS. MOMENTUM TRANSFER ALGORITHM IN BUFKIT SUGGESTS PEAK GUSTS
GENERALLY STAYING A LITTLE SHY OF THIS VALUE /BOTH GFS AND NAM/.
HOWEVER...IT WILL BE WINDY...AND TODAY IS AN IMPORTANT TRAVEL DAY
FOR MANY. TEMPS WILL BE FALLING TODAY...AND THE RELATIVE WARMTH OF
YESTERDAY WILL MAKE THE WIND MORE NOTICEABLE.
WINDS WILL REMAIN STRONG AND GUSTY TONIGHT AND SATURDAY AS THE
SURFACE LOW REMAINS NEARLY STATIONARY OVER IOWA. THE SOUTHWEST LOW
LEVEL FLOW WILL PREVENT THE FULL FORCE OF THE COLD AIR FROM
ARRIVING. HOWEVER...THE GUSTY WINDS WILL MAKE IT FEEL MUCH COLDER.
ACTUAL AIR TEMPS WILL ONLY BE ABOUT 5 TO 10 DEGREES BELOW NORMAL FOR
THIS TIME OF YEAR.
WITH ALL THE IMPULSES PINWHEELING AROUND THE UPPER LOW...THERE WILL
BE SOME UNSETTLED WEATHER SATURDAY THROUGH SUNDAY. IT WILL BE TOUGH
TO SQUEEZE OUT MEASURABLE SNOW GIVEN LIMITED MOISTURE AND MINIMAL
SURFACE TROUGHING. FORECAST WILL CONTINUE TO HIGHLIGHT FLURRIES AND
SLIGHT CHANCE POPS THIS WEEKEND.
TEMPS WILL LIKELY BE COLDER THAN GFS MOS THROUGH THE WEEKEND. USED
VARYING COMBINATIONS OF NAM MOS/NAM 2 METER TEMPS/SREF 2 METER TEMPS
THROUGH MOST OF THE WEEKEND.
LOOKING AHEAD TO NEXT WEEK...THE UPPER LOW WILL DEPART TO THE EAST
MONDAY...GIVING WAY TO A MORE ZONAL FLOW PATTERN FOR MID WEEK.
MODELS HAVE BEEN SHOWING SOME TYPE OF WEAK 500 MB SHORTWAVE PASSING
THROUGH THE MISSISSIPPI VALLEY ABOUT WEDNESDAY. A SLIGHT CHANCE OF
LIGHT SNOW OR POSSIBLY RAIN IN THE SOUTH EXISTS WITH THIS SYSTEM.
&&
.AVIATION...
STRONG UPPER LOW WILL BE LIFTING NORTH OF THE QUAD STATE QUICKLY
THIS MORNING. WILL SEE SCATTERED MAINLY RAIN SHOWERS ACROSS THE AREA
THROUGH 15Z OR SO. SOME LIGHT SNOW IS LIKELY OVER SOUTHEAST
MISSOURI...WELL WEST OF KCGI...THIS MORNING. SOME MVFR VISIBILITIES
WILL DEFINITELY BE POSSIBLE.
MAIN CONCERN BEYOND 15Z IS WHETHER CEILINGS WILL BE MVFR OR LOW VFR.
WITH MVFR CEILINGS LURKING UPSTREAM OVER SOUTHERN MISSOURI AND
NORTHERN ARKANSAS...DECIDED TO TEMPO MVFR CEILINGS FOR 4 HOURS
STRADDLING MIDDAY AT ALL TAF SITES.
WINDS HAVE BECOME SOUTHWEST AT ALL TERMINALS NOW...AND THEY SHOULD
BE STRONG AND GUSTING 25-30KTS IN MOST LOCATIONS THROUGH THE DAY.
VFR CEILINGS WILL LINGER OVER THE AREA THROUGH THE NIGHT...BUT THEY
WILL BE HIGHER THAN DURING THE DAY. LIKEWISE...SOUTHWEST WINDS WILL
DIMINISH SOME WITH SUNSET...BUT WILL CONTINUE THROUGH THE NIGHT AT
OVER 10KTS SUSTAINED.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
KY...WIND ADVISORY UNTIL 6 PM CST THIS EVENING FOR BALLARD-CALDWELL-
CALLOWAY-CARLISLE-CHRISTIAN-CRITTENDEN-DAVIESS-FULTON-
GRAVES-HENDERSON-HICKMAN-HOPKINS-LIVINGSTON-LYON-MARSHALL-
MCCRACKEN-MCLEAN-MUHLENBERG-TODD-TRIGG-UNION KY-WEBSTER.
MO...WIND ADVISORY UNTIL 6 PM CST THIS EVENING FOR BOLLINGER-BUTLER-
CAPE GIRARDEAU-CARTER-MISSISSIPPI-NEW MADRID-PERRY MO-
RIPLEY-SCOTT-STODDARD-WAYNE MO.
IL...WIND ADVISORY UNTIL 6 PM CST THIS EVENING FOR ALEXANDER-EDWARDS-
FRANKLIN-GALLATIN-HAMILTON-HARDIN-JACKSON-JEFFERSON-JOHNSON-
MASSAC-PERRY IL-POPE-PULASKI-SALINE-UNION IL-WABASH-WAYNE
IL-WHITE-WILLIAMSON.
IN...WIND ADVISORY UNTIL 6 PM CST THIS EVENING FOR GIBSON-PIKE-POSEY-
SPENCER-VANDERBURGH-WARRICK.
&&
$$
PUBLIC...MY
AVIATION...DRS
