FXUS64 KHUN 021935
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
134 PM CST WED DEC 2 2009
.MESOSCALE UPDATE...
SHALLOW CONVECTION HAS DEVELOPED DURING THE PAST COUPLE OF HOURS
ALONG THE CDFNT JUST E OF THE I-65 CORRIDOR. THE WARM SECTOR HAS
REACHED NWD TO THE TN RIVER E OF I-65 WITH TEMPS IN THE L60S WITH
DEW POINTS AROUND 60F. THE WEDGE FRONT WAS STILL HOLDING ON AND
ENHANCING THIS BOUNDARY FURTHER IN NRN GA INTO FAR NERN AL. AS A
RESULT...0-1KM SRH IS RUNNING AOA 400 M2/S2 IN NERN AL. WITH SOME
BREAKS IN THE CLOUDS JUST AHEAD OF THE CONVECTION...WEAK SHALLOW
INSTABILITY IS AIDING THE CONVECTION. THUS...ALTHOUGH LIMITED...WE
WILL MONITOR RADAR CLOSELY FOR SHALLOW MESO-CYCLONE DEVELOPMENT
ALONG THIS LINE OF SHRA.
.DISCUSSION...
THE SFC LOW HAS NOW ADVANCED INTO SRN TN JUST W OF LAWRENCEBURG
WITH THE POWERFUL UPPER LOW OVER SRN AR. A DRY SLOT IS WRAPPING
WELL INTO THE SYSTEM THRU AL INTO MIDDLE TN AND WRN KY. LOW
CIGS AND DRIZZLE SHOULD PERSIST INTO THE EVENING HOURS AT LEAST AS
THE MOIST COOLER AIR NOW OVER THE LWR MS VALLEY ADVECTS AROUND THE
LOW INTO THE TN VALLEY. TEMPS AND DEW POINTS WERE RAISED A FEW
DEGREES TNGT BASED ON THIS UPSTREAM AIRMASS. EVENTUALLY...THE
COOLER AIR OVER THE MO VALLEY SHOULD ADVECT AROUND THE CIRCULATION
ON THURSDAY. MODEL GUIDANCE SUGGESTS A REDUCTION IN THE LOWER
CLOUDS BY LATE THU...BUT HAVE REMAINED PESSIMISTIC ON TEMPS
KEEPING THEM IN THE M40S. IF WE CLEAR OUT THU NIGHT...TEMPS SHOULD
FALL BLO FREEZING...ALTHOUGH UPPER JET CI/CS STREAMS IN QUICKLY
AHEAD OF THE NEXT TROF...SO FURTHER ADJUSTMENTS ARE PSBL IN FUTURE
FCSTS.
CONFIDENCE IN -SN IS INCREASING A BIT TDA OVER THIS TIME YDA FOR
FRI NGT/SAT MORN...BUT NOT ENOUGH TO INCREASE POPS/ACCUMS.
THE 00Z GFS ENSEMBLE MEAN KEEPS THE SFC LOW TRACK...IF
ANY...ACROSS THE NRN CENTRAL GULF THRU THE CENTRAL FL PENINSULA.
THIS IS TRADITIONALLY NOT A FAVORABLE TRACK FOR MEASURABLE SN FOR
THE HSV AREA BASED ON A LCL STUDY. THE ATMO WILL ALSO NEED TO
OVERCOME A SIGNIFICANT LYR OF DRY AIR BLO THE MOIST DENDRITIC LYR.
-DIV Q FIELDS SUGGEST WEAK TO MDT Q-G FORCING...MAINLY TO OUR
S...WHILE 7H FN VECTORS ARE SHOWING SOME SIGNAL OF BANDED FORCING
AS WELL. 09Z SREF GUIDANCE IS PROGGING SNOWFALL PROBS IN THE
30-50 PCT RANGE LATE FRI NGT INTO SAT MORN AS WELL...WITH
CUMBERLAND PLATEAU LOCATIONS (I.E. SEWANEE TN AND NERN AL) MOST
FAVORED BY SAT MORNING. WE WILL MAINTAIN SCHC OF -SN AT THIS TIME
GIVEN THAT PREVIOUS GFS ENS MEAN SOLUTIONS HAVE MAINTAINED A
STRONGER HIGH AND LIMITED PRECIP TO OUR S.
FEW CHGS MADE TO THE EXTENDED FCST...WITH GFS ENSEMBLE MEAN MOS
FAVORED ATTM. THE NEXT SUBSTANTIAL THREAT OF PRECIP LOOKS TO BE ON
DAY 8.
&&
.PRELIMINARY POINT TEMPS/POPS...
HUNTSVILLE 40 46 30 46 29 / 40 10 0 10 20
SHOALS 41 47 30 46 29 / 40 10 0 10 20
VINEMONT 40 46 30 45 29 / 30 10 0 10 20
FAYETTEVILLE 40 45 29 43 27 / 40 10 0 10 20
ALBERTVILLE 38 46 30 46 31 / 30 10 0 10 20
FORT PAYNE 40 46 30 44 27 / 40 10 0 10 20
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&
$$
AK
