Area Forecast Discussion
Issued by NWS Charleston, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KCHS 301205
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
805 AM EDT SAT AUG 30 2014

.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL EXPAND WESTWARD THROUGH THE WEEKEND AND
PREVAIL THROUGH AT LEAST THE MIDDLE OF NEXT WEEK. A COLD FRONT COULD
APPROACH THE REGION LATE NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
WHILE THE EXPANSIVE DEEP LAYERED RIDGE HOLDS FIRM TODAY AND
TONIGHT...ATTENTION TURNS TO THERMODYNAMICS AND THE MESOSCALE TO
GENERATE MAINLY SHALLOW SEA BREEZE AND BOUNDARY DRIVEN SHOWERS AND
PERHAPS A FEW THUNDERSTORMS THIS AFTERNOON. DEEPER MOISTURE AND
BETTER INSTABILITY IS POSITIONED FROM SOUTHWEST GEORGIA TO
NORTHEAST FLORIDA AND MAINLY SOUTH OF THE ALTAMAHA RIVER
REGION...WITH CONVECTIVE COVERAGE ACROSS THE LOCAL FORECAST AREA
EXPECTED TO REMAIN MAINLY ISOLATED. THE WEAK ONSHORE TRAJECTORIES
AND ONSET OF THE SEA BREEZE LATE MORNING COULD INITIATE ISOLATED
SHOWERS ALONG THE COAST...BEFORE THE RISK FOR SPOTTY RAIN SHIFTS
INLAND DURING THE AFTERNOON. RAIN CHANCES WILL GENERALLY BE IN THE
20 PERCENT RANGE. WARMEST TEMPERATURES WILL BE OVER INLAND GEORGIA
ZONES...RISING SOLIDLY IN THE MID 90S.

TONIGHT...MAINLY DRY WEATHER...WITH PERHAPS AN ISOLATED SHOWER AT
THE BEACHES AND BARRIER ISLANDS AFTER MIDNIGHT. THERE WILL BE
ANOTHER CHANCE FOR PATCHY FOG ACROSS INLAND AREAS TOWARD DAYBREAK
SUNDAY.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
SUNDAY AND SUNDAY NIGHT...THE CENTER OF THE UPPER RIDGE ALOFT AND
ASSOCIATED ANTICYCLONE WILL MOVE VERY LITTLE AND REMAIN NEARLY RIGHT
ON TOP OF THE FORECAST AREA. SIMILARLY...THE SURFACE PATTERN WILL
FEATURE ATLANTIC HIGH PRESSURE NOSING IN FROM THE EAST AND
CONTROLLING THE LOW LEVELS. MUCH OF THE FORECAST AREA WILL CONTINUE
TO SEE VERY DRY MID/UPPER LEVELS...THOUGH BETTER MOISTURE WILL EXIST
ACROSS SOUTHEAST GEORGIA IN THE AFTERNOON/EVENING HOURS. SOUNDINGS
SHOW A NOTABLE CAP IN THE 700-800 MB LAYER ACROSS THE SOUTH CAROLINA
ZONES. I HAVE NOT MADE ANY CHANGES TO THE POP FORECAST...WHICH STILL
FEATURES CHANCES POPS ACROSS SOUTHEAST GEORGIA AND ALONG THE
SAVANNAH RIVER...WITH ONLY SLIGHT CHANCES ELSEWHERE DURING PEAK
HEATING. OVERNIGHT...ANY LINGERING ACTIVITY WILL DIMINISH IN THE
EVENING WITH JUST SLIGHT CHANCES OVER THE COASTAL WATERS LATE. LOOK
FOR HIGHS IN THE LOW/MID 90S AND LOWS IN THE MID/UPPER 70S.

MONDAY THROUGH TUESDAY...THE PATTERN WILL REMAIN QUITE TYPICAL OF
SUMMERTIME WITH RIDGING ALOFT AND ATLANTIC HIGH PRESSURE AT THE
SURFACE. THROUGH THE EARLY WEEK PERIOD...THE UPPER RIDGE WILL BECOME
INCREASINGLY WEST/EAST ORIENTED AS IT RETROGRADES A BIT BACK TO THE
WEST. THE BELT OF WESTERLIES WILL REMAIN NORTH OF THE AREA...AS WELL
AS ANY EMBEDDED SHORTWAVES. THE ATMOSPHERE WILL GRADUALLY BE LESS
HOSTILE TO CONVECTIVE DEVELOPMENT AS MOISTURE IMPROVES ACROSS THE
REGION. HOWEVER...DUE TO THE LACK OF LARGER SCALE
FORCING...PRECIPITATION CHANCES WILL LARGELY BE DRIVEN BY
CONVERGENCE ALONG THE AFTERNOON SEA BREEZE AND SURFACE HEATING
PROCESSES. THIS WILL KEEP THE COVERAGE IN THE ISOLATED TO SCATTERED
RANGE EACH AFTERNOON AND EVENING. THE OVERALL SEVERE THREAT IS QUITE
LOW DURING THIS TIME...BUT AN ISOLATED SEVERE STORM CANNOT BE RULED
OUT DUE TO MESOSCALE BOUNDARY INTERACTIONS. TEMPERATURES WILL
CONTINUE TO BE ABOVE NORMAL WITH HIGHS IN THE LOW/MID 90S AND LOWS
IN THE MID/UPPER 70S.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
LITTLE CHANGE WAS MADE TO THE GOING FORECAST IN THE LONG TERM
PERIOD. THE SOUTHEAST REGION WILL REMAIN UNDER THE INFLUENCE OF THE
RIDGE ALOFT...WHICH WILL ACTUALLY EXPAND BACK EASTWARD AND
STRENGTHEN IN THE MID/LATE TIME FRAME. ATLANTIC HIGH PRESSURE WILL
STILL BE THE PRIMARY SURFACE FEATURE AS IT EXTENDS WESTWARD ACROSS
THE FORECAST AREA. THERE ARE SOME INDICATIONS THAT A FRONT WILL
ATTEMPT TO APPROACH FROM THE NORTH LATE IN THE PERIOD...BUT GIVEN
THE OVERALL PATTERN THE EXPECTATION IS FOR IT TO REMAIN NORTH OF THE
AREA. ABOVE NORMAL TEMPERATURES ARE FORECAST THROUGH THE PERIOD.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
INCREASING LOW LEVEL MOISTURE...COMBINED WITH SEABREEZE AND
BOUNDARY INTERACTIONS...COULD SUPPORT ISOLATED SHRA/TSRA AT BOTH
TERMINALS THIS AFTERNOON. HOWEVER...PREFER TO MONITOR RADAR TRENDS
LATER TODAY TO DETERMINE TIMING AND COVERAGE POTENTIAL BEFORE
ADDING EXPLICIT MENTION OF ANY IMPACTS TO EITHER TAF. MODEL
GUIDANCE IS AGAIN HINTING AT THE POTENTIAL FOR PATCHY FOG
DEVELOPMENT AFTER MIDNIGHT...AND WILL CONSIDER TRENDING TOWARD
THIS SCENARIO WITH LATER TAF ISSUANCES.

EXTENDED AVIATION OUTLOOK...LOW CHANCES OF DIRECT IMPACTS FROM
ISOLATED SHOWERS/THUNDERSTORMS THROUGH EARLY NEXT WEEK. ALSO...LOW
CHANCES FOR EARLY MORNING FOG/STRATUS THROUGH EARLY NEXT WEEK.
OTHERWISE...MAINLY VFR.

&&

.MARINE...
A CONTINUATION OF FAIRLY TRANQUIL MARINE CONDITIONS TODAY AND TONIGHT.
EXPECT LIGHT MOSTLY ONSHORE SOUTHEAST FLOW LESS THAN 15 KT AND
SEAS 2 TO 3 FT.

SUNDAY THROUGH WEDNESDAY...ATLANTIC HIGH PRESSURE CENTERED TO THE
EAST OF THE LOCAL WATERS WILL BE THE PRIMARY FEATURE THROUGH THE
MIDDLE OF NEXT WEEK. THIS WILL DRIVE A PERSISTENT SOUTH TO SOUTHWEST
FLOW THROUGH MOST OF THE PERIOD. FOR MUCH OF THE PERIOD...WINDS WILL
BE LESS THAN 15 KT. THEY COULD INCREASE INTO THE 15-20 KT RANGE AT
TIMES...ESPECIALLY WITH THE AFTERNOON SEA BREEZE ALONG THE LAND/SEA
INTERFACE AND IN NOCTURNAL SURGES. SEAS WILL GENERALLY BE 2 FT
ACROSS THE NEARSHORE WATERS AND 2-3 FT FOR THE OUTER WATERS. OVERALL
CONDITIONS ARE EXPECTED TO STAY BELOW SMALL CRAFT ADVISORY
THRESHOLDS THROUGH THE PERIOD.

&&

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

&&

$$

NEAR TERM...WMS/
SHORT TERM...BSH
LONG TERM...BSH
AVIATION...WMS/
MARINE...BSH






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.