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000
FXUS62 KCAE 051218
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
718 AM EST THU DEC 5 2013

.SYNOPSIS...
A PREDOMINANTLY WARM AND MOIST SOUTHERLY FLOW IS EXPECTED THROUGH
FRIDAY...ALONG WITH WELL ABOVE NORMAL TEMPERATURES. A COLD FRONT
WILL PUSH INTO THE REGION ON SATURDAY AND WAVER OVER THE MIDLANDS
THROUGH MONDAY WITH A SERIES OF WAVES MOVING ALONG IT. UNSETTLED
WEATHER AND COOLER TEMPERATURES ARE EXPECTED THIS WEEKEND INTO
EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
717 AM EST UPDATE...QUICK UPDATE TO REMOVE DENSE FOG ADVISORY
FROM THE NORTHERN ZONES. VSBYS HAVE IMPROVED THERE ABOVE ONE HALF
MILE.

MORNING ANALYSIS REVEALS UPPER RIDGING ALOFT OVER THE FORECAST
AREA...RESULTING FROM A DEEP UPSTREAM POSITIVELY TILTED TROUGH
EXTENDING FROM THE DAKOTAS BACK TO SOUTHERN CALIFORNIA. AT THE
SURFACE...DEEPENING LOW PRESSURE WAS LIFTING THROUGH THE GREAT
LAKES WITH A COLD FRONT EXTENDING SOUTHWARD THROUGH THE WESTERN
OHIO VALLEY INTO THE DEEP SOUTHERN PLAINS. A WARM FRONT WAS ALSO
LOCATED ACROSS SOUTHERN SOUTH CAROLINA AND SOUTHERLY FLOW
OVERRUNNING THIS BOUNDARY HAS RESULTED IN WIDESPREAD DENSE FOG
ACROSS MUCH OF THE FORECAST AREA.

WEAK SHORTWAVE ENERGY WITHIN THE SOUTHWESTERLY MID LEVEL FLOW IS
LIFTING NORTHEASTWARD TOWARD THE FORECAST AREA AND REGIONAL RADAR
SHOWS AN AREA OF RAIN ASSOCIATED WITH THIS FEATURE OVER SOUTHWEST
GEORGIA. THE NAM AND OTHER HI-RES MODELS ARE IN REASONABLE
AGREEMENT WITH BRINGING THIS BATCH OF RAIN NORTHEASTWARD INTO THE
FORECAST AREA DURING THE 12Z-18Z TIME FRAME. TREND IN MOS GUIDANCE
POPS HAS BEEN INCREASING AS WELL SO HAVE INCREASED POPS INTO THE
LIKELY RANGE FOR THE WESTERN HALF OF THE FORECAST AREA WHILE
MAINTAINING A SHARP GRADIENT IN POPS TO NOTHING OR SLIGHT CHANCE
IN THE EASTERN MIDLANDS. AS THE SHORTWAVE MOVES BY MID MORNING THE
RAINFALL SHOULD DIMINISH AND SHIFT NORTH OF THE AREA WITH LOWER
POPS EXPECTED THIS AFTERNOON AND BEING CONFINED TO THE WESTERN
MIDLANDS AND CSRA. WARM AND MOIST SOUTHERLY FLOW AND LOW LEVEL
THICKNESS RISES WILL SUPPORT WARM AND WELL ABOVE NORMAL
TEMPERATURES WITH MAX TEMPS IN THE 70S EXPECTED.

TONIGHT...SOMEWHAT CONFLUENT MID LEVEL FLOW OVER THE SOUTHEAST AND
A DECREASE IN PRECIPITABLE WATER VALUES DOWN TO AROUND 1.3-1.4
INCHES SHOULD HELP PREVENT MUCH IN THE WAY OF PRECIPITATION
ACROSS THE FORECAST AREA. WILL MAINTAIN SOME LOW POPS ACROSS THE
WESTERN MIDLANDS DUE TO THE SOUTHWESTERLY FLOW ALOFT AND THE
DIFFICULTY IN PICKING UP ON ANY WEAK DISTURBANCES IN THE FLOW.
OVERNIGHT LOWS WILL BE QUITE MILD AS PLENTY OF CLOUDS ARE EXPECTED
ALONG WITH LIGHT SOUTHERLY WINDS WHICH WILL KEEP THE WARM BOUNDARY
LAYER MIXED OVERNIGHT. EXPECT MIN TEMPERATURES TO BE NEARLY 20
DEGREES ABOVE NORMAL IN THE LOWER 60S. A FEW HIGHEST MINIMUM
TEMPERATURE RECORDS MAY BE WITHIN REACH TONIGHT.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
THE COLD FRONT ON FRIDAY MORNING WILL BE SITUATED FROM THE MID
ATLANTIC SOUTHWESTWARD THROUGH THE SOUTHERN APPALACHIAN MOUNTAINS
INTO THE WESTERN GULF COAST AND WILL NOT MAKE MUCH EASTWARD
PROGRESS DUE TO NEARLY PARALLEL UPPER FLOW TO THE FRONTAL
ORIENTATION...LEAVING THE FORECAST AREA WELL WITHIN THE WARM
SECTOR. 850MB TEMPERATURES FRIDAY AFTERNOON APPROACH +14C TO +15C
WITH DEEP SOUTHWESTERLY FLOW IN THE LOWEST 20000FT OF THE
ATMOSPHERE WITH PRECIPITABLE WATER VALUES BELOW 1.5 INCHES. SHOULD
AGAIN SEE WELL ABOVE NORMAL MAX TEMPERATURES APPROACHING BUT
PROBABLY NOT REACHING RECORD HIGHS IN THE UPPER 70S TO AROUND 80
IN SOME LOCATIONS. THINK MOST OF THE AREA WILL REMAIN DRY FRIDAY
DUE TO A LACK OF ANY FORCING. THE COLD FRONT WILL BEGIN TO PUSH
INTO THE FORECAST AREA BY SATURDAY MORNING AS SHORTWAVE ENERGY
QUICKLY MOVES ACROSS THE OHIO VALLEY INTO THE NORTHEAST. CHANCES
OF RAIN INCREASE FROM THE NORTH LATE FRIDAY NIGHT AS THE FRONT
APPROACHES AND LOW LEVEL CONVERGENCE INCREASES. MOST OF THE
PRECIPITATION ASSOCIATED WITH THE FRONT FIGURES TO BE POST FRONTAL
WITH THE STRONGEST ISENTROPIC LIFT AND LOW LEVEL FORCING OCCURRING
WITH THE OVERRUNNING OF THE SOUTHWESTERLY FLOW ALOFT OVER THE COLD
DOME OF THE DENSE POLAR AIR MASS. LOWS FRIDAY NIGHT WILL AGAIN BE
EXTREMELY WARM IN THE WARM SECTOR AND HIGHEST MINIMUM TEMPERATURE
RECORDS MAY BE WITHIN REACH.

SATURDAY THROUGH SUNDAY WILL FEATURE A CHALLENGING FORECAST AS THE
COLD FRONT SLIPS SOUTHEASTWARD THROUGH THE FORECAST AREA BY
SATURDAY EVENING BUT THEN TRIES TO RETURN NORTHWARD AS A WARM
FRONT ON SUNDAY IN RESPONSE TO A SHARPENING UPPER TROUGH OVER THE
CENTRAL PART OF THE COUNTRY. TEMPERATURE ON SATURDAY WILL BE
HIGHLY DEPENDENT ON THE LOCATION OF THE FRONT AND HOW QUICKLY IT
CAN PUSH THROUGH THE FORECAST AREA. EXPECT A STRONG GRADIENT IN
MAX TEMPS FROM AROUND 60 NORTHERN MIDLANDS TO LOWER 70S IN THE
SOUTHEASTERN MIDLANDS AND HOURLY TEMPERATURES MAY FALL A BIT
THROUGH THE DAY IN THE NORTHERN PART OF THE FORECAST AREA.
PRECIPITATION IS EXPECTED TO DEVELOP ALONG AND BEHIND THE FRONT
WITH THE BEST CHANCES ACROSS THE NORTHERN MIDLANDS AND HAVE BUMPED
POPS INTO THE CATEGORICAL RANGE WITH LIKELY POPS DOWN THROUGH THE
COLUMBIA AND AUGUSTA METRO AREAS...WITH HIGH CHANCE POPS
SOUTHEAST. PERSISTENT SOUTHWESTERLY FLOW ALOFT OVERRUNNING THE
COLD NORTHEASTERLY LOW LEVEL FLOW BEHIND THE FRONT...STRENGTHENED
BY INCREASED SURFACE RIDGING DOWN THE EAST COAST...WILL RESULT IN
THE DEVELOPMENT OF A COLD AIR DAMMING WEDGE SATURDAY NIGHT AND
CONTINUING INTO SUNDAY. PERIODS OF LIGHT RAIN EXPECTED SATURDAY
NIGHT INTO SUNDAY ASSOCIATED WITH THE WEDGE. TEMPERATURES WILL
FALL SATURDAY NIGHT INTO THE 40S WITH LITTLE IMPROVEMENT OR RISE
IN TEMPERATURES EXPECTED ON SUNDAY EXCEPT FOR POSSIBLY THE FAR
SOUTHEASTERN MIDLANDS.

WARM ADVECTION WITH INCREASING LOW LEVEL SOUTHERLY FLOW IN THE
FORM OF A 40 KT LOW LEVEL JET SHOULD ERODE THE WEDGE FROM THE
SOUTH SUNDAY NIGHT AND EXPECT TEMPERATURES TO GRADUALLY RISE
THROUGH THE NIGHT AND RAIN CHANCES SHOULD DECREASE FROM SOUTH TO
NORTH AS THE FORECAST AREA FALLS BACK INTO THE WARM SECTOR AGAIN.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
ANOTHER COLD FRONT WILL PUSH THROUGH THE AREA SOMETIME MONDAY
AFTERNOON INTO TUESDAY MORNING AS AN UPPER TROUGH MOVES ACROSS THE
OHIO VALLEY MONDAY AND OFF THE MID ATLANTIC COAST BY TUESDAY.
CHANCES OF RAIN WILL REMAIN OVER THE FORECAST AREA UNTIL THE FRONT
CLEARS THE REGION AND DRY CONDITIONS ARE EXPECTED TO RETURN
TUESDAY NIGHT AND CONTINUE THROUGH WEDNESDAY AS HIGH PRESSURE
BUILDS INTO THE REGION. HIGHEST CHANCES FOR RAIN SHOULD BE MONDAY
AND MONDAY NIGHT AS PRECIPITABLE WATER VALUES INCREASE AGAIN TO
AROUND 1.7 INCHES...POOLING ALONG AND JUST AHEAD OF THE
FRONT...COMBINED WITH UPPER FORCING AND LOW LEVEL CONVERGENCE.
TEMPERATURES ON MONDAY WILL BE MILD AGAIN IN THE 60S TO LOWER 70S
BUT WILL COOL OFF INTO THE 50S ON TUESDAY WITH ABUNDANT CLOUDS AND
RETURNING NORTHERLY FLOW. MUCH COOLER AIR WILL RETURN BY WEDNESDAY
UNDER HIGH PRESSURE.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
DENSE FOG ADVISORY HAS BEEN DROPPED.  DENSE FOG HAS IMPROVED TO
MVFR PATCHY IFR VSBYS. VFR CIGS EXPECTED THRU THE DAY WITH BRIEF
MVFR CIGS/VSBYS IN SPOTTY RAIN SHOWERS AFT 15Z THRU THE AFTERNOON.

EXTENDED AVIATION OUTLOOK...STRATUS AND FOG ARE POSSIBLE AGAIN
LATE TONIGHT AND FRIDAY MORNING BECAUSE OF CONTINUED HIGH LOW-
LEVEL MOISTURE IN THE SOUTH FLOW WELL AHEAD OF AN APPROACHING COLD
FRONT. SHOWERS AND ASSOCIATED RESTRICTIONS WILL OCCUR SATURDAY AND
SUNDAY ASSOCIATED WITH THIS SLOW MOVING FRONT.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&

$$