FXUS62 KCAE 120804
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
304 AM EST SAT DEC 12 2009
.SYNOPSIS...
MOISTURE WILL INCREASE TODAY AHEAD OF LOW PRESSURE IN THE GULF OF
MEXICO. LOW PRESSURE WILL DEVELOP NEAR THE SOUTH CAROLINA COAST
TONIGHT AND LIFT NORTH OF THE AREA SUNDAY. ANY PRECIPITATION
TODAY MAY INITIALLY BE MIXED WITH A LITTLE SLEET BECAUSE OF THE
COLD AIR IN PLACE AHEAD OF THE LOW PRESSURE SYSTEM.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A DRY AIR MASS WAS IN PLACE EARLY THIS MORNING. SURFACE DEW POINT
TEMPERATURES WERE IN THE LOWER TO MIDDLE 20S. MOISTURE WILL BE ON
THE INCREASE TODAY AHEAD OF THE LOW PRESSURE SYSTEM IN THE GULF OF
MEXICO. THE GFS AND NAM ARE CLOSE WITH THE TIMING OF DEEPER MOISTURE
SPREADING INTO THE AREA FROM THE SOUTH. EXPECT SIGNIFICANT
PRECIPITATION WILL HOLD OFF UNTIL THE AFTERNOON. THE EVAPORATIVE
COOLING POTENTIAL SUPPORTS POSSIBLE SLEET...BUT DO NOT EXPECT SLEET
WILL BE SIGNIFICANT BECAUSE OF THE DELAYED TIMING OF THE MOISTURE
AND DIURNAL WARMING. THE MODELS INDICATE JUST LIGHT PRECIPITATION
AMOUNTS UNTIL VERY LATE IN THE DAY AND THIS APPEARS REASONABLE
BECAUSE OF THE INITIAL DRYNESS AND WEAK ISENTROPIC LIFT.
TEMPERATURES WILL BE SLOW TO RISE BECAUSE OF THE WEDGE PATTERN.
THE MOS TEMPERATURES APPEAR A LITTLE TOO WARM.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
THE NAM AND GFS ARE IN GOOD AGREEMENT SHOWING DEEP MOISTURE AND
ISENTROPIC LIFT TONIGHT. WILL FORECAST CATEGORICAL POPS AND USE AN
AVERAGE OF THE GFS AND NAM FOR THE RAIN AMOUNTS. EXPECT GENERALLY
ONE-HALF TO THREE-QUARTERS OF AN INCH OF RAIN. LITTLE CHANGE IN
TEMPERATURE SHOULD OCCUR. THE MODELS ALSO AGREE SHOWING DEEPER
MOISTURE SHIFTING NORTHWARD SUNDAY AS THE COASTAL LOW MOVES UP
THE COAST. EXPECT RAIN WILL DIMINISH BUT IT SHOULD REMAIN CLOUDY
THROUGH THE DAY WITH CONTINUED HIGH LOW-LEVEL MOISTURE. FOG MAY
BECOME A PROBLEM SUNDAY NIGHT BECAUSE OF SHALLOW LOW-LEVEL
MOISTURE WITH LIGHT WIND. USED THE GUIDANCE CONSENSUS FOR THE LOW-
TEMPERATURE FORECAST. THE COLDER TEMPERATURE GUIDANCE APPEARS
BETTER SUNDAY BECAUSE OF EXPECTED CLOUDINESS.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
PLAN LITTLE CHANGE TO THE EXTENDED FORECAST. THE MODELS HAVE BEEN
CONSISTENT SHOWING BRIEF DRY RIDGING FOR MONDAY WITH HIGH MOISTURE
AHEAD OF A COLD FRONT MONDAY NIGHT AND TUESDAY. DRYING BEHIND THE
FRONT APPEARS TO DOMINATE WEDNESDAY THROUGH FRIDAY.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
DRY HIGH PRESSURE OVER THE REGION WILL ENSURE VFR CONDITIONS
THROUGH THIS MORNING. NO FOG EXPECTED DUE TO VERY DRY LOW LEVEL
AIR REMAINING IN PLACE...ALONG WITH MID TO HIGH LEVEL CLOUDINESS.
CONDITIONS WILL BEGIN TO DETERIORATE LATE THIS AFTERNOON AND
EVENING...AS PRECIPITATION SPREADS INTO THE REGION FROM THE SW.
EXTENDED AVIATION OUTLOOK...EXPECT WIDESPREAD SIGNIFICANT
PRECIPITATION LATE SATURDAY NIGHT INTO SUNDAY MORNING WITH IFR
CIGS/VSBYS...AND POSSIBLY LIFR. MOST OF THE PRECIPITATION WILL MOVE
OUT OF THE REGION BY SUNDAY AFTERNOON...BUT LOW CIGS ALONG WITH
PATCHY DRIZZLE AND AREAS OF FOG WILL POSSIBLY REMAIN IN PLACE
THROUGH MONDAY. A COLD FRONT IS EXPECTED TO COME THROUGH LATE
TUESDAY...WITH A CHANCE OF SHOWERS AND ASSOCIATED RESTRICTIONS TO
CIGS/VSBYS. FAIR WEATHER IS EXPECTED WEDNESDAY...WITH BREEZY
CONDITIONS POSSIBLE.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
SYNOPSIS...JL
NEAR TERM...JL
SHORT TERM...JL
LONG TERM...JL
AVIATION...LCV
