FXUS64 KMRX 261933
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
235 PM EST SAT DEC 26 2009
.SHORT TERM (TONIGHT THROUGH MONDAY)...
THE CLOSED LOW OVER THE UPPER MS VALLEY WILL SLOWLY DRIFT TO THE
EAST THROUGH TOMORROW...AND A TRAILING TROUGH/COLD FRONT SWINGS
THROUGH OUR AREA TOMORROW EVENING. MOISTURE WILL BE VERY LIMITED
AHEAD OF THE FRONT...SO SUNDAY LOOKS TO BE DRY WITH INCREASING
CLOUDS THROUGH THE DAY. MOISTURE INCREASES BEHIND THE FRONT...AND
850 MB WINDS INCREASE TO 30 KTS AND SHIFT TO A MORE FAVORABLE
UPSLOPE DIRECTION.
WHILE THE MOISTURE IS NOT VERY DEEP...IT DOES REACH INTO THE
DENDRITE GROWTH ZONE ABOVE -10 C. WITH COLD TEMPS ALOFT CREATING
SOME STEEP LOW LEVEL LAPSE RATES...THE CHANCE OF SNOW SHOWERS LOOKS
PRETTY GOOD FOR SUNDAY NIGHT AND MONDAY MORNING IN SW VA AND THE TN
MOUNTAINS. LARGE-SCALE DYNAMIC LIFT DOES NOT LOOK VERY STRONG TO
FURTHER EHNANCE THE OROGRAPHIC LIFT AND INSTABILITY...SO WILL KEEP
TOTAL SNOW ACCUMULATIONS UNDER 2 INCHES. THE PASSAGE OF THE 500 MB
VORTICITY AXIS AND DECREASING INSTABILITY AND MOISTURE SHOULD END
ANY SHOWERS MONDAY AFTERNOON. LEANED TOWARD THE COLDER NAM MOS
GUIDANCE FOR HIGHS ON MONDAY AS THE GFS MOS LOOKS TOO WARM GIVEN THE
DEEP 850 MB THERMAL TROUGH THAT WILL BE OVER THE AREA. ALSO THE GFS
MOS SEEMS TO BE VERIFYING TOO WARM LATELY.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)...
BROAD UPPER TROUGH ACROSS UPPER GREAT LAKES REGION WILL BE FINALLY
MOVING FAR ENOUGH AWAY FROM THE FORECAST AREA TO LESSEN ITS
INFLUENCE BY 00Z TUESDAY. INITIAL NORTHWEST FLOW AT 500 MILLIBARS
WILL BECOME MORE ZONAL BY 12Z TUESDAY...WITH UPPER LEVEL RIDGING
AND SOUTHWEST FLOW SETTING UP AT 500 MILLIBARS. UPPER LEVEL TROUGH
WILL DIG SOUTHEAST THROUGH THE CENTRAL PLAINS STATES BY 00Z
THURSDAY...WITH RIDGING RELATIVELY SHORT LIVED.
SOUTHERN STREAM SHORT WAVE WILL MOVE NORTHEAST ACROSS THE GULF
COAST REGION BY 00Z THURSDAY TO SOUTH GEORGIA BY 12Z THURSDAY...WITH
GFS FASTER THAN ECMWF SOLUTION AND MUCH FURTHER SOUTH INVOLVING
TRACK OF SYSTEM COMPARED TO ECMWF. THIS SYSTEM IS STILL PROGGED TO
GENERATE SOME RAIN AND MIXED PRECIP ACROSS THE FORECAST AREA.
STILL A LITTLE TOO EARLY TO TELL INVOLVING SPECIFICS AT THIS
TIME INVOLVING WINTRY PRECIP POTENTIAL...BUT WILL BE UPPING POPS A
LITTLE FOR ESPECIALLY THURSDAY AND INTO THURSDAY NIGHT.
BY 12Z NEXT FRIDAY...ECMWF/GFS DEPICT SURFACE LOW OFF SOUTH/NORTH CAROLINA
COAST...WITH FORECAST AREA BEING POTENTIALLY AFFECTED BY A
NORTHWEST FLOW SHORT WAVE DIGGING SOUTHEAST INTO THE TENNESSEE
VALLEY REGION AROUND BASE OF UPPER TROUGH IN OHIO VALLEY REGION.
COLDER AIR SHOULD FILTER INTO THE FORECAST AREA ON FRIDAY...WITH
LIGHT PRECIP A POSSIBILITY ON FRIDAY AND INTO EARLY SATURDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 28 50 28 45 26 / 0 0 10 0 10
KNOXVILLE MCGHEE TYSON AIRPORT, TN 30 47 26 40 25 / 0 10 10 10 10
OAK RIDGE, TN 29 48 28 41 25 / 0 10 10 10 10
TRI CITIES AIRPORT, TN 24 43 24 38 20 / 0 10 20 10 10
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
DGS/TT
