FXUS63 KPAH 240853
AFDPAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
252 AM CST THU DEC 24 2009
.DISCUSSION...
INTENSE UPPER LEVEL SHORTWAVE WILL ACQUIRE A STRONG NEGATIVE TILT AS
IT MOVES NORTHEAST ACROSS OUR REGION THIS EVENING. ASSOCIATED
SURFACE LOW WILL DEEPEN TO AROUND 990 MB AS IT TRACKS NORTH ACROSS
EASTERN MISSOURI TONIGHT. THIS SYSTEM WILL BE ACCOMPANIED BY STRONG
DEEP FORCING FOR ASCENT...RESULTING IN HEAVY RAINFALL. MOST GUIDANCE
REMAINS IN GOOD AGREEMENT THAT AXIS OF HEAVIEST QPF WILL BE ACROSS
SOUTHEAST MISSOURI...CLOSEST TO THE SURFACE LOW TRACK AND POSSIBLY
AIDED BY OROGRAPHIC EFFECTS WITH EAST/SOUTHEAST FLOW ENCOUNTERING
THE OZARK FOOTHILLS. LOCATION AND TIMING OF FLOOD WATCH LOOKS VERY
GOOD. TOTAL RAINFALL STILL LOOKS ON THE ORDER OF A COUPLE OR THREE
INCHES IN THE WATCH AREA...LOCALLY HIGHER IN THE HILLY TERRAIN OF SE
MISSOURI.
AS FOR THE WIND THREAT...THERE WILL BE A STRONG LOW LEVEL FRONTAL
INVERSION. DESPITE TREMENDOUS LOW LEVEL WIND FIELDS /80 KNOTS AT 850
MB/...MIXING THIS WIND DOWN WILL BE DIFFICULT. GFS HAS BEEN
INDICATING 40 KNOTS BARELY OFF THE SURFACE...SO EVEN THE WEAKEST
MIXING CONDITIONS COULD STILL YIELD ADVISORY LEVEL WIND GUSTS.
FOLLOWING THE PASSAGE OF THE OCCLUDED FRONT LATER TONIGHT...MIXING
HEIGHTS WILL RISE RAPIDLY. HOWEVER...WIND FIELDS WILL BE DECREASING
STEADILY. AS A RESULT...WIND GUSTS SHOULD BE MARGINAL FOR AN
ADVISORY. COULD SEE A MESOSCALE TYPE WIND EVENT IMMEDIATELY BEHIND
THE FRONT TONIGHT...BUT THIS IS TOUGH FOR MOST CONVENTIONAL MODELS
TO PICK UP.
ONCE THE OCCLUDED FRONT PASSES...COLDER AIR WILL RUSH IN LATER
TONIGHT AND REMAIN THROUGH THE NEXT SEVERAL DAYS. THE UPPER LOW WILL
BECOME QUASI STATIONARY OVER THE UPPER MISSISSIPPI VALLEY INTO THE
WEEKEND. MODELS ARE INCREASINGLY SHOWING STRONGER IMPULSES ROTATING
AROUND THE LOW...WHICH RESULT IN SOME SPOTTY QPF AND HIGHER MODEL
POPS. DUE TO LIMITED MOISTURE AND MODEL DIFFERENCES IN THE STRENGTH
AND TIMING OF THESE IMPULSES...FLURRIES OR A SLIGHT CHANCE OF LIGHT
SNOW WILL BE FORECAST FRIDAY NIGHT THROUGH SUNDAY.
TEMPS WILL BE A BLEND OF GFS MOS AND SREF 2 METER TEMPS THROUGH
CHRISTMAS NIGHT...THEN AT OR SLIGHTLY BELOW GFS MOS THIS WEEKEND.
AT LONGER RANGES...HIGH PRESSURE WILL MOVE EAST ACROSS THE REGION
EARLY IN THE WEEK. A 500 MB SHORTWAVE OF PACIFIC ORIGIN WILL
APPROACH FROM THE SOUTHWEST ABOUT MID WEEK. THIS SHORTWAVE WILL
INCREASE CLOUDS...BUT FORECAST WILL BE KEPT DRY DUE TO CONCERNS
ABOUT MOISTURE AVAILABILITY AND LACK OF LOW LEVEL FORCING.
&&
.AVIATION...
MVFR CONDITIONS WILL PREVAIL FOR MOST OF THE TAF PERIOD AS A GENERAL
RULE WEST OF THE MISSISSIPPI WHILE AREAS FURTHER EAST WILL SEE RAIN
HOLD OFF UNTIL THURSDAY AFTERNOON WHILE CIGS GRADUALLY LOWER FROM
AROUND 6KFT TO 3KFT. MOST SIGNIFICANT CHANGE THIS UPDATE WAS TO
LIMIT LOWER MVFR/IFR CIGS/VIS TO PERIOD WHEN HEAVIER RAIN IS MOVING
THROUGH JUST AHEAD OF THE COLD FRONT LATE THURSDAY. INCREASING
SOUTHEAST WINDS WILL BECOME AN ISSUE THURSDAY ESPECIALLY KPAH/KCGI.
APPEARS HIGHEST GUSTS OF 30-35KTS OCNL HIGHER WILL HOLD OFF UNTIL
THE LATE AFTERNOON AND EVENING. WINDS SHIFT TO SW OVERNIGHT THU.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
KY...WIND ADVISORY FROM 6 AM THIS MORNING TO 6 AM CST FRIDAY 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...FLOOD WATCH THROUGH THIS EVENING FOR BOLLINGER-BUTLER-CAPE
GIRARDEAU-CARTER-MISSISSIPPI-NEW MADRID-PERRY MO-RIPLEY-
SCOTT-STODDARD-WAYNE MO.
WIND ADVISORY FROM 6 AM THIS MORNING TO 6 AM CST FRIDAY FOR
BOLLINGER-BUTLER-CAPE GIRARDEAU-CARTER-MISSISSIPPI-NEW
MADRID-PERRY MO-RIPLEY-SCOTT-STODDARD-WAYNE MO.
IL...FLOOD WATCH THROUGH THIS EVENING FOR ALEXANDER-EDWARDS-FRANKLIN-
HAMILTON-JACKSON-JEFFERSON-JOHNSON-PERRY IL-PULASKI-SALINE-
UNION IL-WABASH-WAYNE IL-WHITE-WILLIAMSON.
WIND ADVISORY FROM 6 AM THIS MORNING TO 6 AM CST FRIDAY 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 FROM 6 AM THIS MORNING TO 6 AM CST FRIDAY FOR
GIBSON-PIKE-POSEY-SPENCER-VANDERBURGH-WARRICK.
&&
$$
PUBLIC...MY
AVIATION...CW/DRS
