Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 250211
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1011 PM EDT THU JUL 24 2014

.SYNOPSIS...
AN ATLANTIC RIDGE OF HIGH PRESSURE WILL REMAIN SOUTH OF THE AREA
INTO EARLY NEXT WEEK...WITH A WEAK TROUGH OF LOW PRESSURE
PREVAILING INLAND. A COLD FRONT COULD APPROACH LATE MONDAY AND
BECOME STATIONARY SOUTH AND SOUTHEAST OF THE AREA DURING THE
MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
CONVECTION HAS BEEN FIRING IN A REGION OF STRONGER LOW LEVEL MOISTURE
CONVERGENCE NEAR A SURFACE LOW ACROSS THE PEE DEE REGION INTO SE
NORTH CAROLINA WHILE STORMS ARCING BACK TO ABOUT SUMTER SOUTH
CAROLINA. LATEST MODEL DATA CONTINUES TO SHOW SOME HINT OF UPPER
FORCING AND A WEAK TAIL OF A SHORT WAVE PASSING THROUGH NE SOUTH
CAROLINA THROUGH 06Z. BOUNDARIES FROM MULTI-CELL CONVECTION WILL
LIKELY CONTINUE TO PRESS SOUTH AND PERHAPS MOVE INTO AT LEAST
UPPER PARTS OF THE CHARLESTON TRI-COUNTY AREA...SPARKING A FEW
TSTMS OVERNIGHT. NOCTURNAL INSTABILITY IS QUITE DECENT PER 00Z
CHARLESTON SOUNDING ON THE OCEAN-SIDE OF THE LATE DAY RESULTANT
SEA BREEZE. WE MAINTAINED 20/30 POPS FOR A FEW MORE HOURS AS THE
MAIN BRANCH OF CONVECTION RAINS BRUSH BY TO THE NORTH.

TO THE SOUTH...A FEW SHOWERS SEEMED TO BE DISSIPATING TO THE SOUTH
OF I-16 IN GEORGIA AND THIS TREND SHOULD CONTINUE.

A VERY WARM AND MUGGY SUMMER EVENING ONGOING WITH READINGS IN THE
LOW TO MID 80S AT 10 PM...LOW TEMP FORECASTS ON TRACK AND OTHER
THAN VARIOUS SMALL POP AND SKY COVER GRIDS...NOT TOO MANY CHANGES
FOR THE EVENING UPDATE.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
A WEAK FRONT/SURFACE TROUGH WILL BE STALLED NEAR TO JUST NORTHWEST
OF THE AREA THROUGH SATURDAY...THEN LIFT NORTHWARD AND DISSIPATE
BY SUNDAY. A BROAD UPPER TROUGH WILL BE OVER THE REGION FRIDAY AND
INTO SATURDAY. BY SUNDAY...THE UPPER TROUGH IS EXPECTED TO FLATTEN
AND MOVE EAST WAS A DEEP LAYER RIDGE TRIES TO BUILD FROM THE WEST.

DEEP LAYER MOISTURE WILL BE PLENTY SUFFICIENT THROUGH AT LEAST
SATURDAY...WITH PWS 1.8 TO 2.0 INCHES. HOWEVER ONLY REALLY FORCING
FOR CONVECTION WILL BE LOWER LEVEL BOUNDARIES/SEA BREEZE. THINK THE
BEST COVERAGE WILL BE FRIDAY...FROM I-95 EASTWARD TOWARD THE
COAST...AS MAIN STEERING FLOW WILL BE WEST-SOUTHWEST. HAVE KEPT MID
RANGE CHANCE POPS FOR FRIDAY AFTERNOON AND EARLY EVENING. FOR
SATURDAY...SLIGHTLY LOWER MOISTURE VALUES AND EVEN LESS OF AN UPPER
TROUGH...SHOULD TRANSLATE TO SLIGHTLY LOWER POPS...WITH A FOCUS
AGAIN JUST INLAND TO BACK TOWARD THE COAST. BY SUNDAY...DEEP LAYER
MOISTURE WILL GO DOWN A BIT AS MEAN RH VALUES FALL BELOW 50%...AND
ALONG WITH A BUILDING DEEP LAYER RIDGE...EXPECT ONLY ISOLATED MAINLY
AFTERNOON CONVECTION.

TEMPERATURES NEAR NORMAL FRIDAY...THEN MODERATING TO ABOVE NORMAL
SATURDAY AND ESPECIALLY SUNDAY. GUIDANCE CONTINUES TO SHOW MID 90S
FOR HIGHS BOTH SATURDAY AND SUNDAY.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
A DEEP LAYERED GYRE OVER OR NEAR SOUTHERN HUDSON BAY IN CANADA WILL
CIRCULATE OCCASIONAL SHORT WAVES THROUGH THE GREAT LAKES AND OHIO
VALLEY...WHICH IN TURN WILL CARVE OUT A BROAD AND FAIRLY WELL
AMPLIFIED TROUGH ACROSS THE EASTERN HALF OF THE COUNTRY DURING THE
EARLY AND MIDDLE PARTS OF NEXT WEEK. THIS IS DEFINITELY NOT A
SUMMER-LIKE PATTERN...AND IT WILL SEND AN UNUSUAL LATE JULY COLD
FRONT INTO THE AREA FROM THE NW LATER MONDAY AND EARLY TUESDAY.
SURPRISINGLY IT LOOKS LIKE THERE IS ENOUGH NW PUSH BEHIND THE
FRONT TO SEND IT THROUGH THE AREA...BEFORE IT STALLS OUT NOT FAR
TO THE SE AND SOUTH FOR THE MIDDLE OF THE WEEK. RAIN CHANCES WILL
CLIMB MONDAY AND TUESDAY IN CONJUNCTION WITH THE FRONT...MAINLY IN
THE 20-40 PERCENT RANGE. PROVIDED THE FRONT CLEARS THE AREA RAIN
CHANCES ARE NO MORE THAN 20 PERCENT WEDNESDAY...THEN 20-30 PERCENT
NEXT THURSDAY AS THE FRONT STARTS TO TREK BACK NORTH.
COMPRESSIONAL HEATING OUT AHEAD OF THE FRONT ALLOWS FOR ABOVE
NORMAL TEMPS MONDAY...WITH ONLY VERY MINIMAL COOL ADVECTION TO
DROP READINGS SLIGHTLY BELOW NORMAL TUESDAY THROUGH THURSDAY.

&&

.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
THE PATTERN IS QUITE TRICKY ON DETAILS OF WHEN AND WHERE CONVECTION
BREAKS OUT. THIS EVENING...THERE IS STILL POTENTIAL FOR NOCTURNAL
TSTMS AT KCHS PRIOR TO 06Z BUT GIVEN RADAR TRENDS AND RECENT RAP
MESOANALYSIS...WE WILL WAIT FOR ANY TAF INCLUSIONS UNTIL RADAR
TRENDS DICTATE. VFR CONDITIONS TO PREVAIL THROUGH 00Z SAT. CHANCES
FOR TSRA MAY INCREASE FRI AFTERNOON WITH SOMEWHAT BETTER CONVERGENCE
WITH THE SURFACE TROUGH CLOSER TO THE COASTAL AREAS. THUNDER COULD
CERTAINLY BE INTRODUCED ON THE NEXT 1-2 TAF RELEASES FOR FRI
AFTERNOON.

EXTENDED AVIATION OUTLOOK...MAINLY VFR. BRIEF FLIGHT RESTRICTIONS
POSSIBLE IN SCATTERED AFTERNOON AND EARLY EVENING
SHOWERS...ESPECIALLY FRIDAY AND SATURDAY. A COLD FRONT COULD MOVE
INTO THE AREA BY TUESDAY...BUT CONFIDENCE ON THE TIMING AND
STRENGTH OF THIS FRONT IS LOW...GIVEN THAT FRONTS TEND TO STRUGGLE
TO MOVE INTO OUR REGION THIS TIME OF YEAR.

&&

.MARINE...
OVERNIGHT...A TROUGH OF LOW PRESSURE INLAND WILL PROGRESS TOWARD
THE COAST. GOOD MIXING ALONG THE COAST AND NEAR SHORE WATERS THIS
EVENING AS 15 KT WITH GUSTS TO 20 KT AT MID EVENING UP AND DOWN
THE COAST. THE NOCTURNAL JET WILL SLIP OFF THE COAST LATER TONIGHT
WITH SPEEDS DIMINISHING LATE NEAR SHORE. SEAS BETWEEN 3 AND 4 FT
OVER THE WATERS TONIGHT.

NO HIGHLIGHTS EXPECTED THROUGH MUCH OF THE WEEKEND AS THE AREA
REMAINS BETWEEN ATLANTIC HIGH PRESSURE TO THE EAST AND A WEAK TROUGH
OF LOW PRESSURE WELL INLAND. THIS WILL PRODUCE SOUTHWEST WINDS OF
GENERALLY 15 KT OR LESS AND SEAS 2-4 FEET. BY SUNDAY NIGHT AND
MONDAY...THE PRESSURE GRADIENT BEGINS TO TIGHTEN/INCREASE AS SURFACE
PRESSURES LOWER OVER THE MID ATLANTIC AND SOUTHEAST STATES...AND
HIGHER PRESSURE HOLDS ON OVER THE ATLANTIC. CURRENT FORECAST
INCREASES WINDS INTO THE 15-20 KT RANGE WITH SEAS APPROACHING 5 FT
OFFSHORE THROUGH MONDAY NIGHT. A COLD FRONT COULD MOVE INTO THE
WATERS TUESDAY...VEERING WINDS TO LIGHT NORTHERLY.

&&

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

&&

$$

NEAR TERM...
SHORT TERM...RFM
LONG TERM...
AVIATION...
MARINE...





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