FXUS64 KMRX 030846
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
346 AM EST THU DEC 3 2009
.SHORT TERM...(TODAY AND TONIGHT)...POST FRONTAL SFC PRESSURE
GRADIENT LOOSENING UP AS LOW MOVES OUT. WILL CANCEL HIGH WIND
WARNING WITH ISSUANCE OF FORECAST PACKAGE. TRICK TODAY IS TO
DETERMINE HOW MUCH CLOUD COVER WILL PERSIST AND HOW IT WILL AFFECT
TEMPS. BELIEVE THAT CLOUDS WILL STICK AROUND MOSTLY, BUT BEGIN TO
THIN FROM THE WEST DURING THE MORNING. THE MODELS ARE IN PRETTY
GOOD AGREEMENT, BUT HAVE ELECTED TO GO WITH NAM12 FOR THE BRIEF
SHORT TERM PERIOD. ADJUSTED MAX TEMPS DOWN A DEGREE OR SO TODAY,
INLINE WITH OR A TAF BELOW GUIDANCE. THE MINS ALSO DOWN A DEGREE OR
SO TONIGHT AS SKIES CLEAR AND GRADIENT WIDENS. SOME SKINNY AREAS OF
SLIGHT CHANCE POPS IN THE MOUNTAINS AND FAR NORTHEAST THIS MORNING
WITH LINGERING SHOWERS, BUT THESE RAPIDLY MOVE OUT OR DISSIPATE.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)...ONLY MINOR CHANGES MADE TO
MOST FORECAST GRIDS FOR THE EXTENDED PERIODS...EXCEPT FOR SATURDAY.
MODELS SHOWING GOOD CONSENSUS AND CONTINUITY FROM 12Z RUN...WITH A
SWATH OF PRECIPITATION DEVELOPING FROM OUR FORECAST AREA EASTWARD
LATE FRIDAY NIGHT INTO SATURDAY. DEEPENING UPPER LEVEL TROUGH
APPROACHES WITH A STRONG VORT MAX SWEEPING ACROSS SRN PARTS OF THE
FORECAST AREA DURING THE DAY SATURDAY. NO SURFACE TROUGH OR FRONT
...BUT STRONG SYNOPTIC SCALE FORCING WITH ISENTROPIC LIFT AND SOME
MODERATE DIVERGENCE ALOFT. FORECAST SOUNDINGS REVEAL A COLD
ATMOSPHERE WITH DEEP SATURATION...LEADING TO PRECIPITABLE WATER
VALUES FROM 0.40 TO 0.50 INCHES FOR THIS EVENT. 850 MB TEMPS AND LOW
LEVEL THICKNESSES INDICATE MOSTLY SNOW...AND WE SHOULD SEE GOOD SNOW
CRYSTAL GROWTH AS TEMPS AT THE TOP OF THE SATURATED LAYER FALL TO
-20 TO -25 DEGREES CELSISUS.
THUS...FOLLOWED WEATHER WEATHER DESK (WWD) GRAPHICS FAIRLY CLOSE...
WITH SNOW AMOUNTS OF 2 TO NEAR 5 INCHES POSSIBLE BY LATE SATURDAY
AFTERNOON IN THE HIGHER TERRAIN ALONG THE TN-NC LINE...AS WELL AS
HIGHER SPOTS OF SWRN VA. FOR NOW...KEPT OUR PLATEAU COUNTIES AROUND
AN INCH OR SO...AND GENERALLY AN INCH OR LESS OVER THE CENTRAL AND
SRN VALLEY. PUSHED POPS UP TO LIKELY AT THIS POINT. WILL HIGHLIGHT
THIS TREND TOWARD HIGHER POPS AND SOME SNOW ACCUMULATION IN THE
HAZARDOUS WEATHER OUTLOOK (HWO) PRODUCT. THANKS TO GSP AND RNK FOR
COORDINATION ON THESE CHANGES.
OTHERWISE...STAYED CLOSE TO GFSX MOS FOR TEMPS...WITH A SLIGHT
UNDERCUT OVER THE WEEKEND DUE TO SOME SNOW ACCUMULATION POSSIBLE.
WARMER TEMPS EARLY NEXT WEEK WITH NEXT SYSTEM PRODUCING MOSTLY
LIQUID PRECIPITATION. LITTLE TO NO CHANGES MADE FOR MONDAY THROUGH
WEDNESDAY GRIDS.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 49 35 48 33 38 / 10 10 10 30 60
KNOXVILLE MCGHEE TYSON AIRPORT, TN 48 33 46 33 38 / 10 10 10 20 60
OAK RIDGE, TN 48 34 46 32 37 / 10 10 10 20 60
TRI CITIES AIRPORT, TN 47 32 44 31 39 / 10 10 10 20 60
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
BB/TG
