Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 020132
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
932 PM EDT MON JUN 1 2015

.SYNOPSIS...
A COLD FRONT WILL APPROACH FROM THE WEST TUESDAY...STALLING OVER THE
AREA WEDNESDAY INTO THURSDAY BEFORE SLOWLY SHIFTING OFF THE COAST
LATE WEEK. ANOTHER COLD FRONT WILL THEN APPROACH FROM THE NORTHWEST
LATE IN THE WEEKEND INTO EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
CONVECTION REMAINS ACTIVE TO THE WEST OF I-95 AS DEEPER MOISTURE
CONVERGENCE WAS NOTED ON LATEST MESOANALYSIS...EASILY SEEN ON
LATEST SHORT TERM 925 MB AND 850 MB PROGS. ALONG TO THE EAST OF
I-95...THE WEATHER REMAINS DRY BUT DEEPER MOISTURE WILL BE
INCREASING AFTER MIDNIGHT AND WE COULD SEE ISOLATED CONVECTIVE
RAINS DEVELOP DURING THE LATE NIGHT HOURS. WE ARE TRENDING LIKELY
POPS DOWN TO CHANCE WELL INLAND BY AROUND MIDNIGHT WITH LOWER POPS
FOR THE REMAINDER OF THE OVERNIGHT.

THE BOUNDARY LAYER HAS DECOUPLED...RADIATIONAL PROCESSES WILL BE
SEVERELY CURTAILED GIVEN CONSIDERABLE DEBRIS CLOUDINESS EXPECTED
TO LINGER FOR MUCH OF THE NIGHT. THIS WILL RESULT IN A WARMER
NIGHT COMPARED TO PREVIOUS WITH LOWS RANGING FROM THE UPPER
60S/NEAR 70 INLAND TO THE MID 70S AT THE BEACHES. CANNOT RULE OUT
SOME PATCHY FOG INLAND GEORGIA IF DEBRIS CLOUDS THIN LATE.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
TUESDAY...A CLOSED UPPER LOW WILL MOVE INTO THE CENTRAL
APPALACHIANS ON TUESDAY WHILE A PRONOUNCED SHORTWAVE TROUGH PUSHES
THROUGH THE LOCAL AREA OUT AHEAD OF IT. FAIRLY STRONG UPPER LEVEL
DIVERGENCE WILL OVERSPREAD THE AREA DURING THE DAY AS A JET MAX
SHIFTS INTO CENTRAL NC AND THE REGION SITS UNDER THE RIGHT
ENTRANCE REGION. ADDITIONALLY THE LOW AND MID LEVEL FLOW WILL
INCREASE OUT OF THE S-SW...ALLOWING THE TROPOSPHERE TO MOISTEN AND
PRECIPITABLE WATER VALUES TO RISE TO AROUND 1.75". CLOUD COVER
WILL BE FAIRLY EXTENSIVE WHICH WILL LIMIT INSOLATION AND KEEP
TEMPERATURES IN THE MIDDLE 80S. NONETHELESS WITH SFC DEWPOINTS
HOVERING JUST BELOW 70F...CAPES WILL INCREASE TO 1500 TO 2000 J/KG
DURING THE DAYTIME PERIOD WITH LIFTED INDICES -6 TO -8C. THERE
WILL BE AMPLE SYNOPTIC SCALE ASCENT TO SUPPORT NUMEROUS SHOWERS
AND TSTMS DEVELOPING ON TUESDAY...BECOMING MOST EXTENSIVE EARLY TO
MID AFTERNOON. 10-15 KT OF 0-6 KM SHEAR DOES NOT SUPPORT MUCH
STORM ORGANIZATION AND DCAPE PARAMETERS ARE PROGGED AT LESS THAN
500 J/KG. HOWEVER GIVEN THE FORCING AND DECENT CAPE
VALUES...ISOLATED SEVERE TSTMS WITH WET MICROBURSTS CANNOT BE
RULED OUT. A SLIGHTLY GREATER CONCERN WILL BE LOCALIZED FLOODING
WHERE TORRENTIAL RAINFALL TRAINS REPEATEDLY ACROSS THE SAME AREA.

TUESDAY NIGHT...AS THE SHORTWAVE PUSHES EAST...THE BRUNT OF THE
CONVECTION SHOULD PUSH OFF THE COAST TUESDAY EVENING. HOWEVER AS
THE UPPER LOW CONTINUES TO SIT TO OUR WEST AND A RELATIVELY MOIST
AIRMASS PERSISTS...SCATTERED SHOWERS AND TSTMS COULD CONTINUE INTO
THE OVERNIGHT PERIOD.

WEDNESDAY AND THURSDAY...THE CLOSED UPPER LOW WILL MOVE SLOWLY TO
THE E-SE WEDNESDAY INTO THURSDAY WHILE THE COLD FRONT STALLS NEAR
OR OVER THE FORECAST AREA. BASED ON THE POSITION OF THE UPPER LOW
AND VORTICITY ENERGY THAT ROTATES AROUND IT...THE BEST FORCING FOR
CONVECTION WILL BE OVER SOUTHERN SC WEDNESDAY AND THURSDAY.
HOWEVER ALL AREAS WILL AT LEAST SEE SCATTERED SHOWERS AND
THUNDERSTORMS...ESPECIALLY DURING THE AFTERNOON AND EVENING. TEMPS
WILL SHOW A GRADUAL WARMING TREND WITH HIGHS REACHING THE UPPER
80S BY THURSDAY. INSTABILITY PARAMETERS LOOK QUITE SIMILAR TO
TUESDAY WITH CAPES OF 1500-2000 J/KG AND LIFTED INDICES AROUND
-6C. THIS...ALONG WITH PWATS AROUND 1.75" WILL LEAD TO HEAVY
RAINFALL WITH ANYTHING THAT DEVELOPS...ALONG WITH AN ISOLATED
SEVERE THREAT. THE LACK OF SIGNIFICANT SHEAR WILL PRECLUDE A
GREATER SEVERE WEATHER POTENTIAL...BUT WE WILL MONITOR FOR
POSSIBLE FLOODING ESPECIALLY IF HEAVY RAIN OCCURS IN COASTAL
CITIES NEAR HIGH TIDE.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
UNSETTLED CONDITIONS APPEAR TO CONTINUE THROUGH MUCH OF THE LONG
TERM PERIOD. A CLOSED UPPER LEVEL LOW WILL SHIFT OVER THE CAROLINAS
ON FRIDAY...THEN OPEN UP INTO A LONG WAVE TROUGH AS IT SHIFTS OFF
THE COAST ON SATURDAY. A SERIES OF SHORT WAVE DISTURBANCES WILL THEN
TRACK THROUGH WITHIN THE NORTHWEST FLOW ALOFT OVER THE WEEKEND...
BEFORE ANOTHER UPPER LEVEL TROUGH APPROACHES FROM THE NORTHWEST
EARLY NEXT WEEK. GIVEN THIS PATTERN...THE FORECAST WILL REFLECT
SHOWER/THUNDERSTORM PROBABILITIES IN THE 30-50 PERCENT
RANGE...GREATEST DURING THE DAYTIME PERIODS. TEMPERATURES APPEAR TO
REMAIN SLIGHTLY BELOW NORMAL FOR HIGHS...BUT SLIGHT MODIFICATION IS
EXPECTED SUNDAY AND MONDAY.

&&

.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
VFR EXPECTED OVERNIGHT. AN APPROACHING SHORT WAVE AND GRADUALLY
DEEPENING MOISTURE MAY RESULT IN SOME CONVECTIVE RAINS EITHER LATE
TONIGHT INTO TUESDAY MORNING. TUESDAY AFTERNOON LIKELY TO RESULT
IN SCATTERED SHOWERS AND TSTMS ACROSS THE AREA.

EXTENDED AVIATION OUTLOOK...NUMEROUS SHOWERS AND THUNDERSTORMS WILL
AFFECT THE AREA TUESDAY THROUGH FRIDAY...MAINLY DURING THE AFTERNOON
AND EVENING HOURS...PRODUCING OCCASIONAL CEILING AND VSBY
RESTRICTIONS.

&&

.MARINE...
OVERNIGHT...WINDS WILL BE SOUTH 10 KT OR LESS WITH SEAS 2-3 FT.

TUESDAY THROUGH SATURDAY NIGHT...THE LOW LEVEL PATTERN WILL
SUPPORT ONSHORE FLOW WITH SOME MODEST NOCTURNAL SURGING WITH
SPEEDS UP TO 15 KT AT TIMES THROUGH THURSDAY...BEFORE THE FLOW
TAKES ON A MORE NORTHEAST COMPONENT AT TIMES BEHIND THE FRONT
FRIDAY AND SATURDAY. SEAS WILL GENERALLY BE 2 TO 3 FT.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...



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