FXUS64 KHUN 262333 AAA
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
532 PM CST SAT DEC 26 2009

.UPDATE...FOR 00Z AVIATION DISCUSSION
&&

.AVIATION...
WINDS WILL REMAIN GENERALLY IN THE 5-7KT RANGE THROUGH THE OVERNIGHT 
HOURS BEFORE BECOMING GUSTY /TO AROUND 20KT/ BY MIDMORNING SUNDAY. 
CLOUDS WILL ALSO INCREASE THROUGH THE PERIOD...ALTHOUGH VFR 
CONDITIONS ARE EXPECTED TO PREVAIL.
&&

.DISCUSSION.../ISSUED AT 250 PM CST SAT DEC 26 2009/
SLOW MOVING WINTER STORM CONTINUES TO SIT OVER THE UPPER MS
VALLEY. THE NEXT SHORT WAVE TO AFFECT THE AREA EXTENDS FROM THE
LOW CENTER IN WI THRU OK...AND IS SCHEDULED TO ARRIVE SUNDAY
MORNING...WHILE YET ANOTHER WAVE NOW CIRCULATING ON THE NORTH SIDE
OF THE UPPER LOW ALONG THE CANADIAN BORDER ARRIVES LATE SUNDAY
NIGHT AND MONDAY MORNING. A SFC TROF/COLD FRONT ASSOCIATED WITH
THE FIRST WAVE EXTENDS FROM A SFC LOW NEAR THE QUAD CITIES TO JUST
E OF KC TO OKC. AHEAD OF THE FRONT AND WITHIN AN EXTENDED SW-NE
DRY SLOT ON WATER VAPOR IMAGERY...GUSTY SW FLOW HAS DEVELOPED
ACROSS THE MID SOUTH AND TN VALLEYS. WIND GUSTS OVER 30 MPH HAVE
BEEN REPORTED FROM MEMPHIS TO JACKSON TN AND PADUCAH KY. DEW POINTS
HAVE DROPPED INTO THE UPPER TEENS TO LOWER 20S WITH DEEP MIXING.

TONIGHT THROUGH TUESDAY...
20-30KT FLOW JUST ABOVE THE DECOUPLED NEAR SFC LAYER WILL PERSIST
TNGT...SO HAVE ADJUSTED GFS MOS TO ACCOUNT FOR A WIDER RIDGE-
VALLEY SPLIT. SUNDAY SHOULD BE ABOUT THE SAME AS TODAY...WITH
HIGHS NEARING 50 IN SPOTS WITH CONTINUED BREEZY W-SW FLOW AHEAD OF
THE APPROACHING WAVE. ISENTROPIC/DIV Q CHARTS SUGGEST THAT BULK OF
THE LIFT/QG DYNAMICAL SUPPORT WILL STAY WELL TO OUR N.
HOWEVER...SOME LOW LEVEL MOISTENING OCCURS BY SUNDAY EVENING ALONG
AND JUST BEHIND THE COLD FRONT. FAVORABLE NW FLOW WILL PRODUCE
SOME UPSLOPING ALONG THE CUMBERLAND PLATEAU FOR SW-- DVLPMT WITH
MOIST LAYER TEMPS OF -8 TO -10C. THE NAM ALSO PRINTS OUT SOME
LIMITED QPF.

STRONG SUBSIDENCE BY THE SECONDARY WAVE SHOULD ASSURE DRY WX
MONDAY AND TUESDAY. TEMPS NEAR MOS ARE ACCEPTABLE.

TUESDAY NIGHT THROUGH SATURDAY...
TWO SYSTEMS COULD PROVIDE A POTENTIAL WINTRY MIX TO THE AREA...BUT
CONFIDENCE REMAINS QUITE LOW BOTH DUE TO THE THERMAL
PROFILE/P-TYPE PROBLEM AND LIMITED MOISTURE SUPPLY.

ISENTROPIC ASCENT WILL MOISTEN MID LEVELS BY TUE NIGHT...BUT THE
LOW LEVELS WILL REMAIN RATHER DRY...LEADING TO SUBLIMATION OF
FALLING HYDROMETEORS. WILL KEEP POPS IN SCHC RANGE FOR IP/SN BASED
ON FORECAST THERMAL PROFILES AND WET BULB COOLING. PROFILE SHOULD
WARM SUFFICIENTLY FOR ALL RAIN ON TUESDAY DUE TO WARM
ADVECTION...ALTHOUGH THE GULF LOW TRACK IS SOMEWHAT FAVORABLE FOR
A WINTRY EPISODE LOCALLY...SO SOMETHING TO WATCH IN COMING RUNS.

A STRONGER COLD PUSH SHOULD ARRIVE NEW YEARS DAY THAT TIGHTENS THE
THERMAL GRADIENT IN LOW AND MID LEVELS. ONE OF MANY SMALL SHORTWAVES 
IN THE SW FLOW STRIPES THROUGH THE REGION BRINGING SOME POTENTIAL OF 
-SN. IT IS TOO FAR TO JUSTIFY MORE THAN THE GOING SCHC POP. MUCH 
COLDER PUSH OF CP AIR ARRIVES BEHIND THE NEW YEAR'S DAY FRONT. THIS 
AIR MASS APPEARS WILL BE TRAVELING OVER THE LARGE SNOW PACK OVER 
THE NRN CONUS...THUS HAVE CUT MOS SEVERAL DEGREES FRI NIGHT AND SAT.
&&

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&

$$

DISCUSSION...AK
AVIATION...JLL