Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 290754
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
354 AM EDT WED JUL 29 2015

.SYNOPSIS...
A WEAK PRESSURE PATTERN WILL PERSIST OVER THE REGION INTO EARLY
THURSDAY. A COLD FRONT WILL ADVANCE INTO THE REGION FRIDAY AND
WILL STALL THROUGH EARLY NEXT WEEK. HIGH PRESSURE WILL GRADUALLY
INTO THE REGION BY THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
PRE-DAWN...A WEAK PRES PATTERN EARLY THIS MORNING TYPICAL FOR THE
SEASON. INLAND HIGH PRES ACROSS THE CAROLINAS WHILE A WEAK SURFACE
LOW WAS OVER THE ATLC TO THE EAST OF JACKSONVILLE FLORIDA.
SOUNDINGS INDICATE A LOW LEVEL INVERSION BETWEEN 1 KFT AND 2 KFT
ACROSS THE AREA AND SUSPECT WE WILL SEE STRATUS AND LOWER STRATOCU
EXPAND THROUGH SUNRISE BUT NOT CONVINCED WE WILL SEE WIDESPREAD
LOW CLOUDS. FOG DEVELOPMENT IS POSSIBLE ACROSS INLAND AREAS AND WE
MAINTAINED SOME AREAS OF FOG ACROSS INLAND SE GEORGIA.

DISORGANIZED LOW PRES WILL RESIDE OFF THE COAST THROUGH TONIGHT AND
IS FORECAST TO LIFT SLOWLY ENE OR NE. DEEPER MOISTURE PROFILES ARE
MOSTLY SW THROUGH SE OF THE FORECAST AREA TODAY BUT OUR WESTERN
AND SOUTHERN GEORGIA ZONES DO BRUSH THE REGION OF HIGHER PWATS AND
ENHANCED 850 MB TO 500 MB MOISTURE. SINCE THE REGION REMAINS UNDER
THE EASTERN FLANKS OF AN EXPANSIVE UPPER RIDGE...HOT AND HUMID
WEATHER IS ON TAP. HIGH TEMPS WILL WARM TO THE MID 90S MANY AREAS
WITH HEAT INDICES INLAND GEORGIA ZONES REACHING 105-108 DEGREES
THIS AFTERNOON. POPS CAPPED AT 20/30 PERCENT ALONG AND WEST OF
I-95 THIS AFTERNOON...ALIGNED WITH THE DEEP MOISTURE GRADIENT.
SEASONABLY STRONG THERMODYNAMICS WILL BE COUPLED WITH MARGINAL
INSTABILITY AND WARM MID LEVELS TO PRODUCE MOSTLY SPOTTY PULSE
CONVECTION UNTIL MID/LATE AFTERNOON WHEN SCATTERED CONVECTION
DEVELOPS JUST TO OUR W AND SW. ISOLATED STRONGER STORMS COULD CROP
UP FROM EAST CENTRAL GEORGIA TO THE OKEFENOKEE...A FEW OF THESE
STORMS COULD BRUSH LOCATIONS SUCH AS METTER AND REIDSVILLE BUT
OVERALL WE ARE NOT ANTICIPATING MUCH OF A RISK FOR SEVERE WEATHER
ACROSS INLAND GEORGIA.

A FEW SHOWERS AND TSTMS MAY LINGER INTO MID EVENING INLAND ZONES
WEST OF I-95 BUT CONDITIONS SHOULD BE QUIET OVERNIGHT WITH PARTLY
CLOUDY SKIES AND PERHAPS SOME LATE NIGHT FOG AND STRATUS...MAINLY
OVER INLAND ZONES.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
THURSDAY...AN EAST-WEST MOISTURE GRADIENT WILL PERSIST OVER THE
REGION. THUS...AFTERNOON POPS ARE GRADUATED FROM SLIGHT CHANCE NEAR
THE COAST TO CHANCE INLAND...HIGHEST ALONG/WEST OF I-95. MODELS
DEPICT LESS THAN IMPRESSIVE INLAND INSTABILITY. THUS...THE POTENTIAL
FOR SEVERE WEATHER SHOULD REMAIN QUITE LIMITED...UNLESS A STRONGER
MULTICELL THUNDERSTORM CLUSTER WHICH DEVELOPS INLAND CLIPS FAR
INLAND COUNTIES. OUTSIDE THUNDERSTORMS/BEFORE THUNDERSTORMS
DEVELOP...TEMPERATURES IN THE MID 90S SHOULD BECOME COMMON AWAY FROM
THE COAST...AND HEAT INDEX VALUES COULD PEAK IN THE 100-105F RANGE
AT MANY LOCATIONS.

THURSDAY NIGHT...INLAND THUNDERSTORM COVERAGE/INTENSITY SHOULD
GRADUALLY WANE. HOWEVER...TO VARYING DEGREES GUIDANCE DEPICTS
SUFFICIENT MOISTURE SPREADING INTO THE REGION FROM THE
NORTH/NORTHWEST TO SUPPORT ISOLATED SHOWERS/THUNDERSTORMS THROUGH
THE OVERNIGHT. THUS...MAINTAINED ONGOING SLIGHT CHANCE POPS AFTER
MIDNIGHT.

FRIDAY AND SATURDAY...A COLD FRONT WILL ADVANCE INTO THE REGION AND
WILL STALL. THE ASSOCIATED TROUGH AT THE SURFACE AND ALOFT WILL
SETTLE OVER THE REGION AND WILL FOCUS A POOL OF PWATS EXCEEDING 2
INCHES...1-3 STANDARD DEVIATIONS ABOVE NORMAL...OVER THE AREA. THIS
REGIME WILL SUPPORT PERIODS OF ACTIVE CONVECTION FEATURING LIKELY
POPS ACROSS MANY AREAS ESPECIALLY FRIDAY AFTERNOON/EVENING AND AGAIN
SATURDAY AFTERNOON/EVENING. LOCALLY GREATER POPS COULD EVENTUALLY BE
REQUIRED.

THE POTENTIAL FOR PULSE SEVERE WEATHER COULD ACTUALLY BE GREATEST AS
THUNDERSTORMS FIRE AND EXPAND IN COVERAGE FRIDAY AFTERNOON. OF
GREATER CONCERN...HIGH PWATS AND WEAK TROPOSPHERIC WINDS WILL
SUPPORT HIGH RAINFALL RATES AND ERRATIC STORM PROPAGATION...AND THE
PROBABILITY FOR LOCALIZED EXCESSIVE RAINFALL/FLOODING WILL INCREASE.
OTHERWISE...TEMPERATURES COULD TOP OUT IN THE LOWER/MID 90S BEFORE
THUNDERSTORMS DEVELOP FRIDAY. THEN...HELD TEMPERATURES CLOSE TO 90F
SATURDAY...ALTHOUGH TEMPERATURES COULD HOLD IN THE 80S AT MANY
LOCATIONS.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
THE STATIONARY FRONT...ASSOCIATED DEEP LAYERED TROUGH...WEAK
STEERING WINDS AND RESERVOIR OF ABOVE-NORMAL PWATS WILL PERSIST OVER
THE REGION THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK. THIS
ENVIRONMENT WILL SUPPORT ELEVATED POPS AND A CONTINUING THREAT FOR
LOCALLY HEAVY RAINFALL/SHORT FUSE FLOODING. LIKELY POPS APPEAR
REASONABLE FOR SATURDAY. THEN...MODEL DISAGREEMENT ARISES REGARDING
THE POSITION OF THE TROUGH AND ASSOCIATED AXIS OF DEEPEST MOISTURE
SUNDAY-MONDAY. IF THE ATLANTIC RIDGE ALLOWS THE TROUGH AXIS TO PUSH
OFF THE COAST...THE FOCUS FOR HEAVIEST RAIN WILL SHIFT OVER THE
ATLANTIC WATERS. HOWEVER...IF THE ATLANTIC RIDGE REMAINS STRONGER
AND HOLDS THE TROUGH AXIS AND RICH MOISTURE OVER THE REGION AS
DEPICTED BY THE 29/00Z EUROPEAN...ELEVATED POPS/THE ASSOCIATED
POTENTIAL FOR LOCALLY HEAVY RAIN WILL PERSIST. DUE TO
UNCERTAINTY...CAPPED MAXIMUM POPS AT AROUND 50 PERCENT SUNDAY AND
MONDAY. EVENTUALLY...THE TROUGH WILL EVENTUALLY WEAKEN OR WILL SHIFT
OFFSHORE...ALLOWING HIGH PRESSURE TO GRADUALLY BUILD INTO THE REGION
WITH MORE TYPICAL TEMPERATURES/POPS TUESDAY THROUGH WEDNESDAY.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
LATEST FORECAST SOUNDINGS AT KSAV AND KCHS SUGGEST LESS IMPRESSIVE
FOG STABILITY INDICES/PARAMETERS BUT STILL A DECENT POTENTIAL FOR
LOW CLOUDS IN THE 600 FT TO 1200 FT RANGE NEARING DAYBREAK. WE
MAINTAINED CLOUD TRENDS FROM MVFR TO IFR FROM THE PREVIOUS TAF
CYCLE BUT PLAYED VSBYS A BIT MORE TO THE OPTIMISTIC SIDE. AFTER
MID MORNING...VFR CONDITIONS WILL PREVAIL THROUGH THIS EVENING.

EXTENDED AVIATION OUTLOOK...FOG/STRATUS WILL BE POSSIBLE EACH
MORNING THROUGH THE END OF THE WEEK. LOW CHANCE FOR DIRECT IMPACTS
FROM THUNDERSTORMS WEDNESDAY AND THURSDAY...THEN INCREASING
THUNDERSTORM CHANCES FRIDAY THROUGH THE WEEKEND.

&&

.MARINE...
WITH THE WEAK LOW PRES WELL OFFSHORE...ONSHORE FLOW WILL GENERALLY
PERSIST WITH SPEEDS MAINLY IN THE 10 KT RANGE THROUGH TONIGHT WITH
DIURNAL ENHANCEMENTS OF 10-15 KT ALONG COASTAL CHARLESTON COUNTY
THIS AFTERNOON AND EVENING. SEAS 2 TO 3 FT THROUGH TONIGHT...
HIGHEST BEYOND 20 NM OFFSHORE.

AS A COLD FRONT APPROACHES THEN STALL OVER THE REGION...WINDS WILL
GRADUALLY VEER TOWARD THE SOUTH/SOUTHWEST LATE WEEK INTO EARLY NEXT
WEEKEND. WHILE WIND SPEEDS WILL GENERALLY BE LESS THAN 15 KNOTS...
THE SEA BREEZE CIRCULATION AND PERIODIC NOCTURNAL SURGES COULD PUSH
WINDS TO 15-20 KNOTS. SEAS OF 2 TO 3 FEET WILL REMAIN COMMON...
ALTHOUGH PERIODS OF 4 FT SEAS COULD OCCUR ESPECIALLY AT 20 NM AND
BEYOND. ALSO...THUNDERSTORMS ARE EXPECTED AT ANY TIME LATE WEEK INTO
EARLY NEXT WEEK. THUNDERSTORMS COULD GREATLY ALTER SYNOPTIC WINDS
AND WILL CREATE LOCALIZED HAZARDS...PERHAPS INCLUDING WATERSPOUTS.

&&

.TIDES/COASTAL FLOODING...
ELEVATED HIGH TIDE LEVELS ARE EXPECTED THROUGH THE REST OF THE
WEEK AND THE WEEKEND THANKS TO THE UPCOMING PERIGEAN SPRING TIDE
AND FULL MOON CYCLE. ONSHORE WINDS WILL ALSO PROVIDE ADDITIONAL
ENHANCEMENT AT TIMES...AND SHALLOW COASTAL FLOODING WILL BE
POSSIBLE THROUGH THE WEEKEND ESPECIALLY WITH THE EVENING HIGH TIDE
CYCLE. WILL MAINTAIN THE MENTION IN THE HAZARDOUS WEATHER
OUTLOOK. A COASTAL FLOOD ADVISORY COULD BE ISSUED AROUND HIGH
TIDE LATE THIS AFTERNOON INTO EARLY THIS EVENING FOR DOWNTOWN
CHARLESTON.

&&

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

&&

$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...SPR
LONG TERM...SPR
AVIATION...
MARINE...SPR
TIDES/COASTAL FLOODING...



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