FXUS64 KMRX 242312
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
610 PM EST THU DEC 24 2009
.DISCUSSION...MINOR UPDATE TO INCLUDE SOUTHERN TN VALLEY IN WIND
ADVISORY. HEAVY RAINS PROGGED ALONG SOUTHERN EDGE OF MRX CWA
OVERNIGHT. SON
SHORT TERM (TONIGHT THROUGH FRIDAY NIGHT)...
RAIN IS BEGINNING TO SPREAD NORTHWARD INTO THE SOUTHERN TN
VALLEY...AND THE GFS SEEMS TO HAVE A GOOD HANDLE ON THIS. RAIN WILL
GRADUALLY SPREAD ACROSS THE ENTIRE AREA THROUGH THE
EVENING...ALTHOUGH DOWNSLOPE WINDS IN THE NORTHERN VALLEY MAY LOWER
THE QPF AT ONSET. THE BEST LIFT WILL BE 03Z TO 09 Z TIMEFRAME WHEN
THE NOSE OF THE UPPER JET APPROACHES AND PRODUCES STRONG UPPER
DIVERGENCE. INCREASING 850 MB THETA-E VALUES ALONG WITH SLIGHT
MIDLEVEL COOLING ALSO CREATES SOME WEAK ELEVATED INSTABILITY.
CANNOT RULE OUT AN ISOLATED THUNDERSTORM OVERNIGHT. WHILE PRECIP
MAY BE HEAVY AT TIMES...IT SHOULD BE FAIRLY BRIEF AS THE LIFT AND
INSTABILITY ARE FOCUSED IN A NARROW BAND IN THE MODELS. WITH THE
POTENTIAL FOR A PERIOD OF HEAVY RAIN ALONG WITH MELTING SNOW COVER
IN THE MOUNTAINS...SOME LOCALIZED FLOODING MAY OCCUR...AND THE SPS
WILL BE CONTINUED TO MENTION THIS. MIDLEVEL DRYING WILL LEAD TO
PRECIP ENDING FRIDAY MORNING FROM WEST TO EAST...WITH THE SURFACE
FROPA COMING IN THE AFTERNOON. MORNING CLOUDS FOLLOWED BY COLD
ADVECTION WILL KEEP TEMPS FROM RISING MUCH TOMORROW.
A SIGNIFICANT WIND EVENT STILL APPEARS LIKELY TONIGHT. WIND
OBSERVATIONS FROM AROUND THE AREA INDICATE PEAK GUSTS OF 42 MPH AT
COKER CREEK AND 37 MPH AT COVE MOUNTAIN...WITH MOST SPOTS STILL
GUSTING BETWEEN 20 AND 30 MPH. REGIONAL VWP FROM KHTX IS SHOWING 50
KTS AT ABOUT 1500 FEET. THE SREF...RUC..NAM AND GFS ALL SHOW 75 TO
80 KTS AT 850 MB OVERNIGHT. THE CURRENT WARNING AND ADVISORY AREAS
LOOK GOOD AND WILL BE KEPT AS IS. SUSTAINED WINDS OF 35 TO 50 MPH
ARE EXPECTED IN THE WARNING AREA...AND GUSTS OVER 80 MPH WILL BE
POSSIBLE IN SOME AREAS THAT ARE PRONE TO HIGH WINDS.
LONG TERM (SATURDAY THROUGH THURSDAY)...
MODELS KEEP A DEEP CUT-OFF UPPER-LEVEL LOW OVER THE WESTERN GREAT
LAKES REGION THROUGH SUNDAY ...AND THEN SHIFT IT NORTH AND EAST
MONDAY. MOST OF THE MOISTURE WITH THIS FEATURE WILL BE OVER THE
GREAT LAKES AND OHIO VALLEY. HOWEVER LIGHT PRECIP POSSIBLE NORTHERN
HALF OF THE FORECAST AREA SUNDAY INTO MONDAY. TEMPERATURES WILL BE
COLD ENOUGH FOR SNOW AT NIGHT AND EARLY MORNINGS WITH RAIN DURING
THE WARMEST PART OF THE DAY. AS THIS UPPER LOW AND TROUGH MOVE OUT
MONDAY NIGHT AND TUESDAY HIGH PRESSURE WILL BUILD IN BRIEFLY
TUESDAY. THEN THE SOUTHERN JET STREAM BECOMES ACTIVE NEXT WEEK...AS
ANOTHER LOW PRESSURE SYSTEM EXPECTED TO DEVELOP OVER THE GULF COAST
TUESDAY AND WEDNESDAY. THE GFS AND ECMWF MODELS HAVE DISCREPANCIES
WITH THE EXACT TRACK OF THE SYSTEM...WITH THE GFS MODEL HAVING THE
SYSTEM SPLIT WITH PART OF THE ENERGY GOING INTO THE GREAT LAKES
WEDNESDAY AND THURSDAY AND ANOTHER AREA STAYING SOUTH ALONG THE
GULF COAST. THE ECMWF MODEL HOWEVER KEEPS THE SYSTEM TOGETHER AND
SPREADS A BROAD AREA OF PRECIPITATION INTO THE REGION WEDNESDAY
INTO THURSDAY. TEMPERATURES AGAIN WILL BE COLD ENOUGH FOR SNOW AT
NIGHT AND CHANGING TO RAIN DAYTIME.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 43 49 29 48 30 / 100 20 10 10 10
KNOXVILLE MCGHEE TYSON AIRPORT, TN 42 48 28 46 27 / 100 30 10 10 10
OAK RIDGE, TN 42 47 28 46 29 / 100 30 10 10 10
TRI CITIES AIRPORT, TN 37 50 25 45 22 / 100 80 10 10 20
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...WIND ADVISORY UNTIL NOON EST FRIDAY FOR THE FOLLOWING ZONES:
CHEROKEE...CLAY.
TN...HIGH WIND WARNING UNTIL NOON EST FRIDAY FOR THE FOLLOWING ZONES:
BLOUNT SMOKY MOUNTAINS...COCKE SMOKY MOUNTAINS...EAST
POLK...JOHNSON...MCMINN...NW BLOUNT...NORTH SEVIER...
NORTHWEST CARTER...NORTHWEST COCKE...NORTHWEST GREENE...
NORTHWEST MONROE...SEVIER SMOKY MOUNTAINS...SOUTHEAST
CARTER...SOUTHEAST GREENE...SOUTHEAST MONROE...UNICOI...
WASHINGTON TN...WEST POLK.
WIND ADVISORY UNTIL NOON EST /11 AM CST/ FRIDAY FOR THE
FOLLOWING ZONES: BLEDSOE...BRADLEY...CAMPBELL...CLAIBORNE...
HAMILTON...MARION...MEIGS...MORGAN...RHEA...SCOTT TN...
SEQUATCHIE.
VA...WIND ADVISORY UNTIL NOON EST FRIDAY FOR THE FOLLOWING ZONES:
LEE...RUSSELL...SCOTT...WASHINGTON...WISE.
&&
$$
DGS/TD
