Area Forecast Discussion
Issued by NWS Columbia, SC

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000
FXUS62 KCAE 200108
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
808 PM EST FRI DEC 19 2014

.SYNOPSIS...
MOISTURE WILL INCREASE TONIGHT AS AN UPPER DISTURBANCE CROSSES THE
AREA THROUGH SATURDAY...BRINGING SOME LIGHT RAIN TO THE AREA. AN
UNSETTLED WEATHER PATTERN WILL PERSIST WITH A SERIES OF WAVES
MOVING THROUGH THE REGION THROUGH WEDNESDAY...KEEPING CHANCES OF
RAIN IN THE FORECAST. TEMPERATURES WILL BE BELOW NORMAL.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
MOISTURE WILL INCREASE TONIGHT AHEAD OF THE WEAKENING SHORTWAVE.
ISENTROPIC LIFTING BEGINS IN EARNEST AFTER AROUND 08Z AND
CONTINUES INTO SATURDAY. HIGH RESOLUTION MODELS HAVE PRECIPITATION
REACHING THE AREA AROUND 07Z-09Z. THERE PROBABLY WILL BE AN HOUR
OR SO OF MOISTENING IN THE ATMOSPHERE THAT WILL TAKE PLACE BEFORE
RAIN REACHES THE SURFACE. DESPITE THE MOS GUIDANCE GIVING ONLY
CHANCE POPS THROUGH 12Z WILL CARRY LIKELY POPS AS TIMING OF WARM
ADVECTION PRECIPITATION USUALLY ARRIVES EARLIER THAN FORECAST BY
THE MODELS. TEMPERATURES WILL BE WARMER THAN LAST NIGHT WITH
EXTENSIVE CLOUDS EXPECTED. DESPITE SOME TEMPERATURES FALLING INTO
THE 30S IN THE NORTHERN MIDLANDS ALL LIQUID PRECIPITATION IS
EXPECTED.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
ISENTROPIC UPGLIDE AND LIFT AHEAD OF A MID-LEVEL SHORTWAVE TROUGH
SUPPORTS RAIN SATURDAY. THE MODELS SHOW THE DEEPEST MOISTURE EARLY
AND IN THE SOUTH PART OF THE FORECAST AREA SATURDAY. THE LIFT
APPEARS WEAK AND THE SYSTEM PROGRESSIVE. THE GUIDANCE POPS HAVE
TRENDED DOWNWARD. THE NAM/GFS/ENSEMBLES SHOW RAINFALL AMOUNTS
MAINLY AROUND ONE-TENTH OF AN INCH OR LESS. HIGHEST QPF AMOUNTS
WILL BE ACROSS THE SRN PORTION OF THE CWA...NEAR BEST ISENTROPIC
LIFT. EXPECT LIGHT RAIN. LITTLE TEMPERATURE RECOVERY SHOULD OCCUR
SATURDAY BECAUSE OF CLOUDINESS AND COOL NE SURFACE FLOW. THE
TEMPERATURE GUIDANCE IS LIKELY TOO WARM AND HAVE STAYED WITH
CURRENT TRENDS OF BELOW CONSENSUS.

THE MOISTURE REALLY THINS OUT AS THE S/W EXITS THE REGION TO THE
EAST. BELIEVE THE RAIN CHANCE IS LOW BECAUSE OF LITTLE OR NO
ISENTROPIC LIFT AND FLAT UPPER-LEVEL RIDGING. THE NAM AND GFS MOS
POPS WERE NEAR 10 PERCENT. THE RAIN CHANCE MAY INCREASE BY LATE
SUNDAY BECAUSE OF AN INCREASE IN ISENTROPIC LIFT AND ANOTHER
APPROACHING MID-LEVEL SHORTWAVE TROUGH. THE GUIDANCE CONSENSUS
SUPPORTS POPS OF 20 TO 30 PERCENT LATE IN THE DAY. USED THE
GUIDANCE CONSENSUS FOR THE LOW TEMPERATURE FORECAST SATURDAY
NIGHT...AND THE COOLER GUIDANCE FOR THE HIGH SUNDAY BECAUSE OF
EXPECTED CLOUDINESS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
THE GFS AND ECMWF DISPLAY ANOTHER SURGE OF MOISTURE MOVING INTO
THE FORECAST AREA FROM THE GULF SUNDAY NIGHT INTO MONDAY. THE
STRONGEST LIFT ASSOCIATED WITH THIS SYSTEM APPEARS TO BE LATE
SUNDAY NIGHT INTO EARLY MONDAY. HIGH MOISTURE SHOULD CONTINUE
TUESDAY AHEAD OF THE WARM FRONT AND DEEPENING UPPER-LEVEL TROUGH.
THE MODELS HAVE BEEN CONSISTENT INDICATING A STRONG COLD FRONT
LATE TUESDAY NIGHT OR EARLY WEDNESDAY SUPPORTING CATEGORICAL TO
LIKELY SHOWERS WITH THUNDERSTORMS NOT OUT OF THE QUESTION. WARM
FRONT LOOKS TO BE NORTH OF THE REGION TUESDAY AFTERNOON AS LI
FIELD SHOWS DEPARTING WEDGE ACROSS THE AREA. LIS BETWEEN -1 AND -3
AND STRONG SHEAR INDICATE THE POTENTIAL FOR A FEW STRONG
THUNDERSTORMS. EXPECT A DIMINISHED SHOWER CHANCE WEDNESDAY BEHIND
THE FRONT WITH WINDY CONDITIONS THROUGH THURSDAY. MAY NEED A LAKE
WIND ADVISORY FOR THE AREA ON WEDNESDAY THROUGH THURSDAY WITH GOOD
CAA AND TIGHT PRESSURE GRADIENT. THE GFS AND ECWMF DISPLAY A DRY
WEST FLOW BETWEEN DEEP LOW PRESSURE IN THE GREAT LAKES REGION AND
HIGH PRESSURE IN THE GULF FOR CHRISTMAS DAY.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS EXPECTED THROUGH THE EARLY MORNING HOURS THEN MVFR
CIGS EXPECTED TO DEVELOP AFTER 12Z.

HIGH PRESSURE OVER THE AREA WILL GIVE WAY TO A WEAK LOW PRESSURE
SYSTEM LIFTING NORTH ALONG THE SOUTHEAST COAST. INCREASING
MOISTURE WILL RESULT IN THICKENING CLOUDS WHICH WILL LOWER THROUGH
THE NIGHT AS ISENTROPIC LIFTING BECOMES STRONGER. LIGHT RAIN
EXPECTED TO IMPACT THE TERMINALS BEGINNING AROUND 07Z AGS/DNL AND
09Z CAE/CUB/OGB WITH LOWERING VSBYS IN RAIN AT AGS/DNL/OGB AFTER
12Z. MVFR CIGS EXPECTED AFTER 12Z AS WEDGE STRENGTHENS WITH
SOUTHWESTERLY FLOW ALOFT AND NORTHEASTERLY SURFACE WINDS. RAIN
WILL TAPER OFF TOWARD THE END OF THE TAF PERIOD WHILE MVFR CEILING
RESTRICTIONS HOLD STEADY.

EXTENDED AVIATION OUTLOOK...WIDESPREAD LOW CLOUDS AND
PRECIPITATION EXPECTED SUNDAY NIGHT INTO MONDAY WITH ANOTHER GULF
COAST SYSTEM CROSSING THE REGION. YET ANOTHER SYSTEM WILL AFFECT
THE AREA TUESDAY NIGHT BRINGING POSSIBLE RESTRICTIONS WITH WINDY
CONDITIONS EXPECTED WEDNESDAY.

&&

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

$$





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