357
FXUS62 KCAE 241843
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
243 PM EDT MON SEP 24 2018
SYNOPSIS
A WEAK FRONTAL BOUNDARY STALLED OVER THE MIDLANDS WILL BECOME
DIFFUSE THIS AFTERNOON. A WEDGE OF MOIST HIGH PRESSURE WILL
CONTINUE OVER THE REGION INTO THROUGH TUESDAY. ANOTHER FRONT
WILL MOVE INTO THE REGION LATE WEDNESDAY. THESE FACTORS WILL
LEAD TO INCREASING PRECIPITATION CHANCES BY MID WEEK BUT
TEMPERATURES REMAIN ABOVE NORMAL UNTIL NEXT WEEKEND.
NEAR TERM /THROUGH TONIGHT/
A WEAK FRONTAL BOUNDARY OVER THE MIDLANDS WILL BECOME DIFFUSE
THIS AFTERNOON. SURFACE HIGH PRESSURE CENTERED OVER NEW ENGLAND
WILL CONTINUE TO RIDGE INTO THE CAROLINAS AND GEORGIA...BRINGING
WEDGE-LIKE CONDITIONS. SKIES SHOULD REMAIN CLOUDY ACROSS THE
NORTH MIDLANDS. AREAS FARTHER SOUTH MAY SEE SOME PEAKS OF SUN.
ISENTROPIC LIFT APPEARS WEAK AND MAINLY IN THE SAVANNAH RIVER
BASIN WHERE PRECIPITABLE WATER IS HIGHER. THE EASTERLY FLOW IS
ALSO UPSLOPE IN THIS REGION. WE EXPECT SCATTERED SHOWERS TO
LINGER ACROSS THE CSRA. CONVERGENCE NEAR THE DISSIPATING FRONT
COMBINED WITH DIURNALLY DRIVEN WEAK INSTABILITY COULD LEAD TO
MORE SHOWERS AND PERHAPS A THUNDERSTORM DEVELOPING ACROSS THE
SOUTHERN MIDLANDS THIS AFTERNOON.
TEMPERATURES SHOULD BE COOLER THAN PREVIOUS DAYS, WITH HIGHS
RANGING FROM THE UPPER 70S NEAR THE NC/SC BORDER TO THE UPPER
80S ACROSS THE SOUTHERN MIDLANDS AND CSRA.
THE CHANCE FOR SHOWERS WILL DIMINISH TONIGHT AS INSTABILITY
DECREASES. LOW LEVEL MOISTURE WILL PRODUCE WIDESPREAD CLOUDS.
OVERNIGHT LOWS WILL BE IN THE UPPER 60S AND LOWER 70S.
SHORT TERM /TUESDAY THROUGH WEDNESDAY/
UPPER RIDGE WILL REMAIN OVER THE WESTERN ATLANTIC ON TUESDAY AND
WILL WEAKEN ON WEDNESDAY AS UPPER TROUGH OVER THE UPPER MIDWEST
SHIFTS EAST. A BROAD AREA OF LOW PRESSURE OFF THE SOUTH
CAROLINA COAST TUESDAY MORNING IS EXPECTED TO MOVE NORTHWARD
TOWARD THE OUTER BANKS OF NORTH CAROLINA DURING THE DAY,
ALTHOUGH INCREASING UPPER LEVEL WINDS SHOULD LIMIT ADDITIONAL
DEVELOPMENT. WEAK HIGH PRESSURE WILL REMAIN OVER THE FORECAST
AREA ON TUESDAY WITH A DRIER AIRMASS IN PLACE. PWAT VALUES WILL
BE AROUND 1.5 TO 1.7 INCHES, SO SLIGHT CHANCE POPS APPEAR
REASONABLE. MOISTURE WILL DEEPEN ON WEDNESDAY AHEAD OF A FRONT
APPROACHING FROM THE OH/TN VALLEY REGIONS. PWAT VALUES
INCREASE TO AROUND 1.8 INCHES EAST TO 2.0 INCHES WEST. THE BEST
CHANCE FOR SHOWERS AND THUNDERSTORMS SHOULD BE WEST CLOSER TO
THE APPROACHING FRONT AND DEEPER MOISTURE. INSTABILITY APPEARS
MODERATE WITH LI VALUES AROUND -4 TO -5 DURING THE AFTERNOON.
HIGH TEMPERATURES ON TUESDAY ARE FORECAST IN THE MID 80S NORTH
TO AROUND 90 SOUTH AND AROUND 90 ON WEDNESDAY.
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/
UPPER LEVEL FLOW WILL BECOME MORE WESTERLY HEADING INTO THE
WEEKEND WITH BROAD UPPER TROUGHING FLATTENING OVER THE EASTERN
CONUS. THE FRONTAL BOUNDARY WILL CONTINUE TO APPROACH THE
FORECAST AREA LATE IN THE WEEK AND MAY STALL OVER THE WEEKEND.
THE BEST CHANCES FOR RAIN APPEAR TO BE THURSDAY THROUGH
SATURDAY. ONCE THE FRONT PUSHES THROUGH BY SUNDAY, HIGH
PRESSURE WILL RETURN FOR EARLY NEXT WEEK. EXPECT A GRADUAL
COOLING TREND INTO THE WEEKEND AND EARLY NEXT WEEK BEHIND THE
FRONT.
AVIATION /18Z MONDAY THROUGH SATURDAY/
SURFACE HIGH PRESSURE WILL CONTINUE TO RIDGE INTO THE AREA FROM
THE NORTH PRODUCING WEDGE-LIKE CONDITIONS AND NORTHEAST TO EAST
WINDS. MVFR CIGS ARE EXPECTED TO LIFT TO VFR THIS AFTERNOON AS
THE ATMOSPHERIC MIXING INCREASES. SCATTERED SHOWERS AND PERHAPS
ISOLATED THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AS THE
ATMOSPHERE BECOMES WEAKLY UNSTABLE. SHOWERS HAVE A BETTER CHANCE
OF AFFECTING AGS/DNL/OGB...SO HAVE INCLUDED A TEMPO GROUP
THROUGH EARLY EVENING. SHOWERS WILL BEGIN TO DIMINISH WITH
SUNSET. GIVEN ABUNDANT LOW LEVEL MOISTURE AND NOCTURNAL
COOLING...EXPECT MVFR/IFR CONDITIONS TO REDEVELOP AROUND AFTER
25/06Z. MODELS INDICATE IMPROVING CONDITIONS DURING THE
AFTERNOON TUESDAY AS DRIER AIR FILTERS INTO THE REGION.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE EACH DAY IN
LATE NIGHT/EARLY MORNING FOG/STRATUS AND MAINLY AFTERNOON AND
EVENING SHOWERS AND THUNDERSTORMS AS A FRONTAL BOUNDARY STALLS
ACROSS THE AREA THURSDAY THROUGH SATURDAY.
CAE WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
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