Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 060754
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
354 AM EDT FRI MAY 6 2016

.SYNOPSIS...
AN UPPER LEVEL LOW WILL LINGER TODAY THEN LIFT AWAY FROM THE AREA
TONIGHT. HIGH PRESSURE WILL PREVAIL SATURDAY THROUGH WEDNESDAY
THEN A FRONTAL SYSTEM IS EXPECTED TO AFFECT THE AREA LATE NEXT
WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
PRE-DAWN...A POWERFUL UPPER VORTICITY MAXIMA PUSHED OFF THE COAST
OVERNIGHT WHILE AN UNUSUALLY DEEP CUT-OFF LOW WAS PIVOTING THROUGH
EASTERN NORTH CAROLINA. A STRONG UPPER DEFORMATION ZONE HAS BEEN
ANCHORED OVER THE WESTERN CAROLINAS WHILE CLOUDS HAVE TENDED TO
DISSIPATE MOVING INTO PARTS OF THE LOW COUNTRY. SKIES SHOULD
REMAIN CLEAR ACROSS SE GEORGIA. CHILLY TEMPS THIS MORNING AS LOW
LEVEL COLD AIR ADVECTION HAS BEEN STEADY. A FEW SPOTS WELL INLAND
COULD SEE MID 40S BY DAWN.

ALTHOUGH THE CORE OF THE DEEP UPPER LEVEL LOW WILL LIFT AWAY FROM
THE AREA AND TOWARD THE DELMARVA...BACK-SIDE SHORT WAVES DROPPING IN
FROM THE EASTERN TENNESSEE VALLEY AND ASSOCIATED COLD POOL FEATURING
500 MB TEMPS AS COLD AS -23C WILL SWEEP THROUGH. DESPITE LIMITED
MOISTURE WITH PWATS NO MORE THAN AROUND 3/4 INCHES AND 20-30F
SURFACE DEW POINT DEPRESSIONS...THE ASSOCIATED STEEP LAPSE RATES AND
MODEST QG FORCING WILL SUPPORT THE RISK FOR ISOLATED TO SCATTERED
SHOWERS AND PERHAPS A COUPLE LOW TOPPED T-STORMS NORTH OF A LINE
FROM ALLENDALE TO EDISTO BEACH SOUTH CAROLINA.

FORECAST SOUNDINGS ACROSS SANTEE COOPER LAKES REGION INDICATES
UPWARDS OF 500 TO 800 J/KG SB CAPE THIS AFTERNOON. WITH TOTAL TOTALS
IN THE MID 50S AND LOW WET BULBS AND FREEZING LEVELS IT LOOKS LIKE
JUST ABOUT ANY OF THE CONVECTIVE ELEMENTS COULD PRODUCE SMALL HAIL
OR MELTING GRAUPEL. WE EXPANDED SLIGHT CHANCE POPS A BIT SOUTHWARD
ON THIS PACKAGE TO ACCOUNT FOR THE POTENTIAL FOR SOME LIGHT SHOWERS
DOWN TO NEAR THE SAVANNAH RIVER LATE TODAY AND CANNOT RULE OUT
SOME PATCHY LIGHT SHOWERS OR SPRINKLES ACROSS SE GEORGIA THIS
AFTERNOON BUT MEASURABLE RAINS ARE QUITE UNLIKELY.

MOST AREAS WILL SEE TEMPS STRUGGLE TO REACH THE MID 70S TODAY...
ESPECIALLY SINCE IT LOOKS LIKE A LARGE EXPANSION OF CUMULUS/STRATOCU
DURING THE WARMEST PART OF THE AFTERNOON. WINDS WILL BE MUCH LIGHTER
TODAY BUT STILL FROM THE W AND NW.

TONIGHT...THE BASE OF THE UPPER TROUGH WILL DEPART AND WE WILL SEE
RISING HEIGHTS ALOFT. RADIATIONAL COOLING UNDER CLEARING SKIES SHOULD
RESULT IN LOWS AROUND 50 IN MANY AREAS.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
AN UPPER LEVEL RIDGE WILL TAKE HOLD ACROSS THE SOUTHEAST U.S.
SATURDAY AND PERSIST THROUGH MONDAY AS DRY HIGH PRESSURE SETTLES
IN AT THE SURFACE. SATURDAY WILL FEATURE MOSTLY SUNNY SKIES AND
HIGHS IN THE LOWER 80S. BY SUNDAY...LOW-LEVEL THICKNESSES INCREASE
SUBSTANTIALLY AS THE 850 MB RIDGE BUILDS EAST. THIS WILL YIELD
HIGH TEMPS IN THE UPPER 80S TO AROUND 90 BOTH SUNDAY AND MONDAY
WITH NO RAIN EXPECTED. SUNDAY MORNING LOWS WILL BE AROUND 60 DUE
TO LIGHT WINDS AND MOSTLY CLEAR SKIES. A BIT MORE SKY COVER MONDAY
MORNING WILL HOLD LOW TEMPS IN THE MIDDLE 60S.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
DEEP LAYERED RIDGING WILL PERSIST MONDAY NIGHT THROUGH TUESDAY
NIGHT...MAINTAINING DRY WEATHER AND ABOVE-NORMAL TEMPS. ON
WEDNESDAY SOME UPPER LEVEL VORTICITY ENERGY APPROACHES WESTERN
AREAS...PUSHING A WEAK COLD FRONT TOWARD THE FORECAST AREA. THIS
FRONT IS EXPECTED TO MEANDER OVER THE AREA THURSDAY AND THURSDAY
NIGHT...THEN POSSIBLY MOVING OFFSHORE FRIDAY MORNING. MODEL
INSTABILITY PARAMETERS ARE SUPPORTIVE OF ISOLATED TO SCATTERED
THUNDERSTORMS MID TO LATE WEEK IN ASSOCIATION WITH THE UPPER
SHORTWAVE ENERGY AND THE LINGERING SURFACE FRONT.


&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS ARE EXPECTED TO PREVAIL AT BOTH KCHS AND KSAV
TERMINALS THROUGH 06Z SATURDAY. HOWEVER...CAN/T RULE OUT A
SHOWER/THUNDERSTORM CAUSING FLIGHT RESTRICTIONS AT KCHS THIS
AFTERNOON.

EXTENDED AVIATION OUTLOOK...VFR.

&&

.MARINE...
WE HAVE ALLOWED ALL SMALL CRAFT ADVISORIES TO EXPIRE AT 4 AM EDT
THIS MORNING. THE CYCLONIC FLOW OFFSHORE FLOW AROUND LOW PRESSURE
IN THE MID ATLANTIC REGION WILL EASE A LITTLE ALLOWING FOR W-NW
WINDS THAT ARE AS HIGH AS 15-20 KT EARLY TO DIMINISH TO 10 TO 15
KT THIS AFTERNOON. TRAJECTORIES FROM LAND TO THE OCEAN WILL LIMIT
SEAS TO NO MORE THAN 2-4 FT AND HIGHEST NEAR 50-60 NM OFF THE
GEORGIA COAST EARLY THIS MORNING.

WEAK OFFSHORE FLOW SATURDAY AND SATURDAY NIGHT GRADUALLY SHIFTS TO
SOUTHWEST LATE SUNDAY AS ATLANTIC HIGH PRESSURE BECOMES THE
DOMINANT FEATURE. SUNDAY THROUGH THE MIDDLE OF NEXT WEEK THE MAIN
MARINE HIGHLIGHT WILL BE AFTERNOON SEA BREEZE CIRCULATIONS ALONG
THE COAST THOUGH SPEEDS SHOULD MAINLY STAY BELOW 15 KT.

&&

.TIDES/COASTAL FLOODING...
DESPITE THE OFFSHORE WINDS TODAY AND SATURDAY...GIVEN THE PERIGEAN
SPRING TIDES THERE MIGHT BE A NEED FOR COASTAL FLOOD ADVISORIES
WITH THE EVENING HIGH TIDE CYCLES. THEN ON SUNDAY THE FLOW
ATTEMPTS TO SHIFT A LITTLE MORE ONSHORE...AGAIN CAUSING A RISK FOR
SHALLOW COAST FLOOD CONCERNS WITH THE EVENING HIGH TIDE.

&&

.CLIMATE...
RECORD LOWS FOR MAY 6...

CHARLESTON AIRPORT /CHS/...44/1973
SAVANNAH AIRPORT /SAV/...46/1957
DOWNTOWN CHARLESTON /CXM/...53/1921

&&

.EQUIPMENT...
THE CHARLESTON HARBOR NOS TIDE GAUGE AND GRAYS REEF BUOY 41008 REMAIN
OUT OF SERVICE.

&&

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

&&

$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...JRL
MARINE...JRL
TIDES/COASTAL FLOODING...
CLIMATE...
EQUIPMENT...


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