141 
FXUS62 KCHS 280909
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
509 AM EDT FRI MAR 28 2014

.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL PREVAIL AS WEAK UPPER DISTURBANCES
MOVE THROUGH THE AREA TODAY AND TONIGHT. A COLD FRONT WILL CROSS
THE REGION SATURDAY AFTERNOON AND EVENING...FOLLOWED BY DRY HIGH
PRESSURE THROUGH THURSDAY. A COLD FRONT MAY AFFECT THE AREA NEXT
FRIDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
TODAY...SOUTHERLY RETURN FLOW WILL BECOME WELL ESTABLISHED TODAY
AROUND HIGH PRESSURE SLOWLY DRIFTING ACROSS THE WESTERN ATLANTIC.
THIS WILL ALLOW DEEPER MOISTURE TO ADVECT INTO THE REGION...WITH
PRECIPITABLE WATER VALUES RISING FROM AROUND 1 INCH THIS MORNING
TO 1.25-1.50 INCHES THIS AFTERNOON. ISOLATED TO SCATTERED SHOWERS
AND PERHAPS A FEW THUNDERSTORMS WILL DEVELOP ALONG AN AXIS OF
ENHANCED LOW LEVEL CONVERGENCE JUST OFF THE COAST THIS
MORNING...WITH LOW LEVEL TRAJECTORIES SHIFTING THIS CONVECTION UP
ALONG THE SC COAST AND INTO EASTERN PORTIONS OF THE CHARLESTON
TRI-COUNTY AREA. THEN...THE POTENTIAL FOR SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ACROSS THE REST OF THE AREA WILL INCREASE THROUGH
LATE AFTERNOON AS SHORT WAVE ENERGY EMBEDDED WITHIN THE SOUTHWEST
FLOW ALOFT NEARS. SKIES WILL BECOME MOSTLY CLOUDY ACROSS THE AREA
TODAY AS CIRRUS ASSOCIATED WITH A 110 KT UPPER JET OVERSPREADS THE
AREA AND LOWER CLOUDS INCREASE IN COVERAGE AS MOISTURE DEEPENS.
DESPITE THE CLOUD COVER AND INCREASING POTENTIAL FOR SHOWERS...THE
RETURN SOUTHERLY FLOW SHOULD BE SUPPORTIVE OF HIGHS IN THE MID AND
UPPER 70S ACROSS THE AREA AWAY FROM THE IMMEDIATE COAST. 

TONIGHT...ATLANTIC HIGH PRESSURE WILL PREVAIL AS A COLD FRONT
APPROACHES FROM THE TENNESSEE VALLEY AND DEEP SOUTH. SOUTHERLY
FLOW WILL CONTINUE TO ADVECT DEEP MOISTURE INTO THE REGION. THE
COMBINATION OF THE DEEP LAYERED MOISTURE...FORCING FOR ASCENT
ASSOCIATED WITH THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL
JET...AND A POTENT SHORT WAVE PASSING ALOFT WILL SUPPORT SCATTERED
TO NUMEROUS SHOWERS ACROSS THE AREA...ESPECIALLY LATE THIS EVENING
AND OVERNIGHT. IN ADDITION...INSTABILITY PARAMETERS/MID LEVEL
LAPSE RATES ARE SUPPORTIVE OF AT LEAST ISOLATED THUNDERSTORMS AS
WELL. TEMPERATURES WILL NOT FALL SIGNIFICANTLY GIVEN THE SOUTHERLY
FLOW AND CLOUD COVER...WITH LOWS EXPECTED TO BE AROUND 60 IN MOST
AREAS. 

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
A POTENT UPPER SHORTWAVE WILL MOVE INTO THE CENTRAL APPALACHIANS ON 
SATURDAY. SOUTHWEST FLOW WILL STRENGTHEN CONSIDERABLY AS THE DAY 
WEARS ON...WITH 0-6 KM WINDS 40-45 KT BY 00Z SUN. THIS WILL ALSO 
INCREASE MOISTURE ACROSS THE AREA WITH PWATS ABOVE 1.50 INCHES BY 
18Z SAT. A COLD FRONT IS EXPECTED TO SWEEP THROUGH THE AREA SATURDAY 
EVENING. THERE REMAINS CONSIDERABLE UNCERTAINTY REGARDING THE DEGREE 
OF BOUNDARY LAYER DESTABILIZATION AHEAD OF THE FRONT. GIVEN THE 
EXTENSIVE LOW-LEVEL MOISTURE ADVECTING INTO THE REGION DURING THE 
DAY WE WOULD EXPECT TO HAVE QUITE A BIT OF LOW STRATOCUMULUS IN 
PLACE. HOWEVER SOME OF THE GUIDANCE IS DEPICTING A WEAK DRY SLOT 
DURING THE MIDDAY HOURS AFTER A BATCH OF MORNING PRECIP MOVES 
THROUGH. BOTH THE GFS AND NAM ARE SHOWING 1500 J/KG CAPES WITH 
LIFTED INDICES BELOW -4C DURING THE AFTERNOON ACROSS SOUTHEAST GA. 
THIS COINCIDES WITH 40-45 KT OF BULK SHEAR. IT IS ALSO WORTH NOTING 
THAT THE STORM PREDICTION CENTER STILL SHOWS OUR ENTIRE FORECAST 
AREA WITHIN THE DAY 2 SLIGHT RISK. WE PLAN TO ADD MENTION OF 
POSSIBLE SEVERE WEATHER TO THE HAZARDOUS WEATHER OUTLOOK.

STRONG LOW-LEVEL WARM ADVECTION AND PRE-FRONTAL COMPRESSION ON 
SATURDAY WILL PUSH HIGH TEMPS INTO THE UPPER 70S. THIS COULD 
POTENTIALLY BE TOO COOL IF SOME BREAKS DEVELOP IN THE CLOUDS. 
CONSIDERABLE COVERAGE OF SHOWERS AND THUNDERSTORMS IS EXPECTED 
THROUGH SATURDAY EVENING BEFORE PRECIP TAPERS OFF BEHIND THE FRONT.

A SLIGHT COOL DOWN IS EXPECTED FOR SUNDAY DUE TO COLD ADVECTION WITH 
THE HIGH BUILDING IN...HOWEVER DOWNSLOPE FLOW WILL ALLOW TEMPS TO 
REACH 70 OR THEREABOUTS. A 30-35 KT GEOSTROPHIC WIND FIELD AND DEEP 
MIXING WILL RESULT IN BREEZY CONDITIONS ESPECIALLY DURING THE HOURS 
OF PEAK HEATING.

DRY WEATHER WITH MODERATING TEMPERATURES EXPECTED ON MONDAY WITH 
HIGHS REBOUNDING INTO THE LOWER TO MIDDLE 70S.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
A BROAD UPPER LEVEL RIDGE WILL PREVAIL MONDAY NIGHT THROUGH THURSDAY 
WITH DRY HIGH PRESSURE AT THE SURFACE. THIS WILL RESULT IN ABOVE 
NORMAL TEMPERATURES WITH HIGHS CLIMBING INTO THE UPPER 70S OR LOWER 
80S AND LOWS MAINLY IN THE 50S. THE UPPER RIDGE BREAKS DOWN ON 
FRIDAY WITH A WEAK COLD FRONT POSSIBLY MOVING IN FROM THE WEST.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS SHOULD GENERALLY PREVAIL AT BOTH KCHS AND KSAV
THROUGH AT LEAST THIS AFTERNOON. BRIEF/ISOLATED SHOWERS ARE
POSSIBLE AROUND KCHS FROM JUST PRIOR TO DAYBREAK AND CONTINUING
THROUGH MUCH OF THE MORNING...BUT GIVEN LIMITED COVERAGE AND
OVERALL LOW CONFIDENCE...THERE WILL BE NO MENTION IN THE KCHS TAF.
BREEZY CONDITIONS WILL DEVELOP THIS AFTERNOON WITH GUSTS UPWARDS
OF 20 KT AT TIMES. INCREASING LOW LEVEL MOISTURE COULD RESULT IN
PERIODIC CEILING RESTRICTIONS TO MVFR LEVELS AFTER 00Z. IN ADDITION...
THE POTENTIAL FOR SCATTERED OR EVEN NUMEROUS SHOWERS WILL
INCREASE AFTER 00Z THUS HAVE ADDED VICINITY SHOWERS TO THE
FORECAST AT BOTH TERMINALS.

EXTENDED AVIATION OUTLOOK...OCCASIONAL FLIGHT RESTRICTIONS POSSIBLE 
SATURDAY AFTERNOON AND EVENING IN SCATTERED SHOWERS AND 
THUNDERSTORMS. VFR CONDITIONS EXPECTED THEREAFTER. BREEZY CONDITIONS 
EXPECTED ON SUNDAY.

&&

.MARINE...
TODAY...A SOUTHERLY RETURN FLOW WILL BECOME WELL ESTABLISHED
ACROSS THE COASTAL WATERS TODAY AS ATLANTIC HIGH PRESSURE
PREVAILS. DESPITE SOME STRONGER WINDS ALOFT...MIXING WILL REMAIN
LIMITED OVER THE COOLER NEAR SHORE WATERS THUS WINDS AT THE
SURFACE SHOULD NOT EXCEED 10 TO 15 KT. HOWEVER...WINDS OVER THE
OUTER GA WATERS AND IN CHARLESTON HARBOR ALONG THE LAND/SEA
INTERFACE COULD REACH UPWARDS OF 15 TO 20 KT AT TIMES THIS
AFTERNOON. A SOUTHEAST SWELL WILL KEEP SEAS ELEVATED IN THE 3-5 FT
RANGE TODAY...WITH A SMALL POTENTIAL FOR SOME 6 FT SEAS TO
ENCROACH UPON THE FAR REACHES OF THE OUTER GA WATERS. GIVEN
LIMITED CONFIDENCE...HAVE OPTED TO NOT ISSUE A SMALL CRAFT
ADVISORY...ALTHOUGH CONDITIONS COULD WARRANT OTHERWISE LATER
TODAY. DEW POINTS SURGING INTO THE LOWER 60S WITHIN THE SOUTHERLY
FLOW COULD SUPPORT THE DEVELOPMENT OF PATCHY SEA FOG LATER THIS
AFTERNOON ACROSS THE NEAR SHORE WATERS.

TONIGHT...THE SOUTHERLY FLOW WILL STRENGTHEN TO UPWARDS OF 15 TO
20 KT ACROSS THE COASTAL WATERS AS THE SURFACE PRESSURE GRADIENT
TIGHTENS BETWEEN ATLANTIC HIGH PRESSURE AND A COLD FRONT WELL TO
THE WEST. A SOUTHEAST SWELL WILL KEEP SEAS SOLIDLY IN THE 3-5 FT
RANGE...HIGHEST ACROSS THE OUTER GA WATERS. THERE IS A SMALL
POTENTIAL THAT MARGINAL SMALL CRAFT ADVISORY CONDITIONS FOR WINDS
AND/OR SEAS COULD OCCUR OVER THE OUTER GA WATERS...BUT NOT ENOUGH
CONFIDENCE TO RAISE AN ADVISORY AT THIS TIME. THE POTENTIAL FOR
PATCHY SEA FOG WILL PERSIST TONIGHT ACROSS THE NEAR SHORE WATERS
AND CHARLESTON HARBOR AS A WARM/MOIST SOUTHERLY FLOW PREVAILS.

SATURDAY THROUGH TUESDAY...WIND FIELDS WILL INCREASE SATURDAY INTO SATURDAY
NIGHT AS A STRONG COLD FRONT MOVES THROUGH. ON SATURDAY THE FLOW
WILL BE OUT OF THE SOUTH AND CONDITIONS SHOULD REMAIN BELOW
ADVISORY CRITERIA. BUT ONCE COLD ADVECTION CRANKS UP LATE SATURDAY
EVENING AND OVERNIGHT AND GEOSTROPHIC WINDS INCREASE TO 35-40
KT...WE EXPECT SMALL CRAFT ADVISORY CONDITIONS ON MOST IF NOT ALL
MARINE ZONES. CONDITIONS WILL QUICKLY IMPROVE ON SUNDAY AS THE
HIGH PRESSURE CENTER MOVES CLOSER TO THE WATERS. FAIRLY QUIET
WINDS/SEAS ANTICIPATED SUNDAY NIGHT THROUGH MID WEEK AS THE HIGH
PRESSURE DOMINATES.

&&

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

&&

$$

SYNOPSIS...
NEAR TERM...JAQ
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...JAQ/JRL
MARINE...JAQ/JRL