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Area Forecast Discussion

190
FXUS62 KCHS 041833
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
133 PM EST WED MAR 4 2015

.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL EXTEND ACROSS THE REGION TODAY. A
STRONG COLD FRONT WILL APPROACH FROM THE NORTHWEST ON THURSDAY AND
PASS OFF THE COAST EARLY THURSDAY EVENING. COLDER HIGH PRESSURE
WILL BUILD OVER THE AREA INTO SATURDAY...WITH A COASTAL TROUGH TO
DEVELOP OFFSHORE LATE IN THE WEEKEND. ANOTHER STORM SYSTEM COULD
IMPACT THE AREA EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
DESPITE A DECENT CUMULUS FIELD TEMPERATURES HAVE SOARED TO AROUND
80/LOWER 80S INLAND WHILE THE IMMEDIATE COASTAL LOCALES LIKE FOLLY
BEACH REMAIN IN THE 50S/60S. AM NOW FORECASTING SAVANNAH TO REACH
THEIR RECORD HIGH OF 84 DEGREES BUT CHARLESTON SHOULD FALL JUST
SHY. LOOKS LIKE THE SEA FOG LINGERS NEAR THE COAST AND IT COULD
TRY TO PUSH INLAND AS THE SEA BREEZE STRENGTHENS AND WINDS BECOME
MORE ONSHORE/SOUTHERLY. BREEZY SOUTH TO SOUTHWEST WINDS WILL
CONTINUE AS WELL WITH GUSTS 25-30 MPH.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
TONIGHT...IT WILL BE A WARM AND HUMID NIGHT ACROSS THE REGION. THE
ATMOSPHERE LOOKS TO REMAIN WELL MIXED WITH ANOTHER PRE-FRONTAL
LOW-LEVEL JET TRAVERSING THE REGION. DO NOT ANTICIPATE FOG TO BE A
SIGNIFICANT PROBLEM EARLY THURSDAY WITH BOUNDARY LAYER-975 HPA
WINDS HOLDING IN THE 15-30 KT RANGE. SOUTHWEST SURFACE TRAJECTORIES
SHOULD KEEP ANY SEA FOG OVER THE ATLANTIC...ALTHOUGH SOME MAY
BRUSH THE CHARLESTON COUNTY COAST GIVEN THE ORIENTATION OF THE
COAST THERE. LOWS WILL RANGE FROM THE LOWER 60S INLAND TO THE
UPPER 50S/NEAR 60 AT THE COAST.

THURSDAY...WILL LIKELY START OFF VERY MILD WITH WIDESPREAD LOW
CLOUDS THAT SHOULD ERODE PRIOR TO LATE MORNING MOST AREAS SETTING
THE STAGE FOR A WARM...OCCASIONALLY BREEZY AFTERNOON AHEAD OF
RAINS APPROACHING IN ADVANCE A COLD FRONT. WE BUMPED UP TEMPS JUST
A BIT MORE ON THIS MORNINGS PACKAGE TO SHOW MORE HIGHS TOUCHING 80
DEGREES AND EVEN A FEW LOWER 80S IN SE GEORGIA. DEW POINTS WILL BE
AT OR SLIGHTLY ABOVE 60 DEGREES THROUGH EARLY AFTERNOON. WE BACKED
OFF A BIT ON TIMING SHALLOW CONVECTIVE RAINS THROUGH THE FORECAST
AREA FROM MID AFTERNOON WEST TO CLOSER TO LATE IN THE AFTERNOON
ALONG THE COAST. INSTABILITY IS VERY WEAK WITH POOR LAPSE RATES
AND MUCAPES BELOW 500 J/KG DESPITE THE WARM TEMPS AND ELEVATED
SURFACE DEW POINTS. WE HAVE A SHORT WINDOW FOR AN ISOLATED TSTMS
BUT NOT LOOKING FOR ANY SIGNIFICANT CONVECTION RISK.

THURSDAY NIGHT...THE STRONG COLD FRONT ACCOMPANIED BY IMPRESSIVE
COLD AIR ADVECTION WILL MOVE WELL OFFSHORE FRIDAY NIGHT AND
SHOWERS WILL DECREASE FROM WEST TO EAST OVERNIGHT. TEMPS WILL
BEGIN A FREE-FALL INTO THE 30S ACROSS NORTHERN ZONES TOWARD
DAYBREAK WITH READINGS FALLING INTO THE 40S ACROSS SE GEORGIA.

FRIDAY...FRIDAY LOOKS LIKE AN INTERESTING DAY AS MODELS IN
GENERAL AGREEMENT ON DEVELOPING A SECONDARY AREA OF RAINS ACROSS
THE FORECAST AREA AS A MID LEVEL SHORT WAVE MOVES INTO THE SE
STATES. THERE LOOKS TO BE GOOD UPPER FORCING FOR ASCENT AND THE
BIG QUESTION WILL BE SURFACE TEMPS AS THE SHALLOW AND COLD CP AIR
MASS BECOMES ENTRENCHED. NAM/GFS SOUNDINGS LOOK VERY COLD AND WE
WILL HAVE TO WATCH FOR SOME FREEZING RAIN POTENTIAL ACROSS OUR
NORTHERN SOUTH CAROLINA ZONES. SURFACE WET BULB TEMPS ARE PROGGED
TO BE NEAR OR JUST BELOW FREEZING OVER INTERIOR PORTIONS OF
SOUTHEAST SC SO WILL HAVE TO WATCH THIS CAREFULLY OVER THE NEXT 24
HOURS. OTHERWISE...IT APPEARS TO BE A VERY COLD RAIN WITH TEMPS IN
THE UPPER 30S TO LOWER 40S COMING ON THE HEELS OF AN 80 DEGREE
DAY.

SATURDAY...HIGH PRES THEN THEN BUILD OVER THE REGION THROUGH
SATURDAY. CLEARING AND COLD FRIDAY NIGHT WITH A POTENTIAL FREEZE
OR FROST ISSUE ALONG AND NORTH OF I-16. A GOOD BIT OF SUNSHINE AND
DRY WEATHER IS LIKELY ON SATURDAY WITH HIGHS WELL BELOW CLIMO...IN
THE 50S MOST AREAS.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
THERE REMAINS A GOOD BIT OF UNCERTAINTY IN THE LONG TERM PERIOD
AS AN ACTIVE BAROCLINIC ZONE IS EXPECTED TO WAVER FROM THE
NORTHERN GULF COAST REGION AND FLORIDA LATE IN THE WEEKEND TO
GEORGIA AND THE CAROLINAS DURING EARLY TO MID WEEK. GLOBAL MODELS
DIFFER ON TIMING AND STRENGTH OF THESE IMPULSES MOVING THROUGH THE
SE STATES DURING THIS TIME. WITH PERIODS OF CLOUDS AND SHOWERS
POSSIBLE FROM TIME TO TIME...TEMPS WILL PROBABLY BE NEAR OR
SLIGHTLY BELOW CLIMO.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
EXPECT VFR TO PERSIST THROUGH ABOUT 08Z WHEN LOW CLOUDS DEVELOP
AND/OR ADVECT IN FROM THE SOUTHWEST. SOME SEA FOG COULD ALSO
IMPACT THE TERMS...ESPECIALLY KCHS. WE KEPT CONDS NO WORSE THAN
MVFR FOR NOW BUT THEY COULD GO LIFR TOWARD DAYBREAK...ESPECIALLY
CIGS. THE OTHER ISSUE WILL BE GUSTY WINDS...MAINLY IN THE
AFTERNOON...DUE TO THE STRONG LOW- LEVEL JET OVER THE AREA AHEAD
OF AN APPROACHING COLD FRONT...AS WELL AS MARGINAL LOW LEVEL WIND
SHEAR TONIGHT AS SFC WINDS SUBSIDE TO LESS THAN 10 KT.

EXTENDED AVIATION OUTLOOK...ADDITIONAL FLIGHT RESTRICTIONS
POSSIBLE THURSDAY NIGHT INTO FRIDAY ALONG WITH GUSTY N TO NE
SURFACE WINDS. CONDITIONS EXPECTED TO IMPROVE OVER THE WEEKEND
WITH HIGH PRES AND VFR.

&&

.MARINE...
TODAY...AREAS OF DENSE SEA FOG WILL PERSIST ACROSS THE COASTAL
WATERS THROUGH THIS AFTERNOON...MAINLY NEAR SHORE...AS AN
UNSEASONABLY WARM AND HUMID AIR MASS REMAINS IN PLACE AHEAD OF AN
APPROACHING COLD FRONT. WILL WATCH FOR THE POTENTIAL OF DENSE FOG
ROLLING BACK INTO CHARLESTON HARBOR LATER THIS AFTERNOON AS WINDS
BECOME MORE SOUTHERLY. OTHERWISE... EXPECT MOSTLY SOUTH WINDS
AROUND 15 KT TO PREVAIL. IT COULD GET RATHER GUSTY IN THE
CHARLESTON HARBOR FOR A FEW HOURS THIS AFTERNOON AS THE RESULTANT
SEA BREEZE MOVES INLAND.

TONIGHT...SEA FOG WILL PERSIST THROUGH THE NIGHT...ESPECIALLY OVER
THE SOUTH CAROLINA WATERS WHERE SOUTHWEST TRAJECTORIES WILL FAVOR
LONGER PARCEL RESIDENCE TIMES OVER THE COLD SHELF WATERS. ANOTHER
MARINE DENSE FOG ADVISORY MAY BE NEEDED. WINDS WILL GENERALLY
REMAIN AROUND 15 KT WITH SEA BUILDING 2-4 FT NEARSHORE...EXCEPT
3-5 FT OVER THE GEORGIA OFFSHORE AND CHARLESTON COUNTY WATERS.

THURSDAY...SW SYNOPTIC FLOW IN THE WARM SECTOR WILL STRUGGLE TO
MIX ACROSS ALL BUT OUR WARMEST OUTER GEORGIA WATERS AHEAD OF
ADVANCING COLD FRONT ON THURSDAY. SPEEDS WILL MAINLY BE AT OR EVEN
LESS THAN 15 KT BUT IT COULD BECOME SOMEWHAT GUSTY ALONG THE
LAND/SEA INTERFACE IN THE AFTERNOON. PATCHY TO AREAS OF SEA FOG
COULD CERTAINLY BE LINGERING OVER THE COLDER SHELF WATERS INTO THE
DAY.

THURSDAY NIGHT THROUGH SUNDAY NIGHT...A STRONG COLD FRONT WILL
BLAST THROUGH THE WATERS THURSDAY NIGHT ACCOMPANIED BY SOLID SMALL
CRAFT ADVISORY CONDITIONS AND AT LEAST A SMALL CHANCE FOR GALES
OFF THE CHARLESTON COUNTY COAST AND THE GEORGIA WATERS FROM 20 TO
60 NM. WHILE WINDS SHIFT NNE AND GUST THURSDAY NIGHT INTO
FRIDAY...SEAS WILL BUILD TO 4 TO 6 FT NEAR SHORE AND 8-10 FT WELL
OFF THE GEORGIA COAST. HIGH PRES WILL BUILD OVER THE WATERS DURING
THE WEEKEND WILL NE FLOW DECREASING ON SATURDAY...THEN LIGHTER
MORE VARIABLE WINDS ON SUNDAY INTO EARLY NEXT WEEK.

&&

.CLIMATE...
RECORD HIGHS FOR 4 MARCH...
KCHS... 83/2004
KCXM... 80/1899
KSAV... 84/1955

RECORD HIGHS FOR 5 MARCH...
KCHS... 85/1997
KCXM... 84/1923
KSAV... 86/1955

RECORD LOW MAXIMUMS FOR 6 MARCH...
KCHS... 43/1960
KCXM... 43/1960
KSAV... 42/1901

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...DENSE FOG ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR AMZ350-
     352-354.

&&

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



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