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Area Forecast Discussion

247
FXUS62 KCHS 251529
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1029 AM EST TUE NOV 25 2014

.SYNOPSIS...
A SLOW MOVING COLD FRONT WILL STALL JUST OFF THE COAST TODAY. AN
AREA OF LOW PRESSURE WILL DEVELOP OFF THE GEORGIA COAST THIS
AFTERNOON AND LIFT NORTHEAST TONIGHT THROUGH EARLY WEDNESDAY. DRY
HIGH PRESSURE WILL BUILD INTO THE SOUTHEAST UNITED STATES WEDNESDAY
AND REMAIN THE MOST PROMINENT FEATURE THROUGH EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
OUR BLOCKING ATLANTIC RIDGE HAS FINALLY SHIFTED FURTHER EAST AND
SE IN ADVANCE OF A DEEP AND LARGE SCALE MID LATITUDE TROUGH MOVING
THROUGH THE GREAT PLAINS. BETWEEN THESE TWO FEATURES IS A DEEP
INFLUX OF TROPICAL MOISTURE WITH IT/S ORIGINS ALL THE WAY FROM THE
EASTERN PACIFIC...AS SHOWN CLEARLY ON SATELLITE IMAGERY. THIS IS
SUPPLYING THE REGION WITH AN ANOMALOUSLY HIGH FEED OF MOISTURE
WITH PWATS THAT ARE APPROACHING MAXIMUM VALUES FOR LATE NOVEMBER.

AT THE SURFACE WE FIND A DECAYING COLD FRONT WEST OF US-301 IN SE
GA INTO THE MIDLANDS OF SC. A MORE PROMINENT BOUNDARY THAT/S
DEVELOPING IS FOUND OUT OVER THE GULF STREAM WHERE A STATIONARY
FRONT IS FORMING OVER A PRE-EXISTING BAROCLINIC ZONE. THIS FRONT
WILL BECOME THE MAIN PLAYER IN OUR WEATHER LATER TODAY AND MORE SO
TONIGHT.

A POWERFUL SHORT WAVE ROUNDING THE BASE OF THE LARGE SCALE TROUGH
THROUGH SOUTHERN TEXAS IS STARTING TO SUPPORT CYCLOGENESIS IN THE
GULF OF MEXICO AS PER SATELLITE PICTURES WHICH ARE INDICATING A
BURST IN CONVECTION AND COLDER CLOUD TOPS. THIS DEVELOPING LOW
WILL HEAD TOWARD THE FLORIDA BIG BEND BY LATE IN THE DAY AS IT
RIDES ALONG THE PRE-EXISTING STATIONARY FRONT/BAROCLINIC ZONE.

WE/RE DEFINITELY IN FOR A WET DAY...ALTHOUGH WE/RE A LITTLE UNCERTAIN
IF THE RAINS WE/RE SEEING THIS MORNING WILL START TO DIMINISH IN
INTENSITY AND AREAL COVERAGE...AND THE ACTIVITY WILL TRANSITION
INTO THE COASTAL WATERS IN CLOSER PROXIMITY TO THE STATIONARY
FRONT. OR WILL THESE TWO RAIN AREAS JUST MERGE TOGETHER. THE POP
SCHEME IS SHOWING HIGHEST CATEGORICAL POPS THIS MORNING...THEN
MAYBE A SMALL DECLINE THIS AFTERNOON WHILE THE TRANSITION ATTEMPTS
TO TAKE PLACE...THEN POPS RAMPING BACK UP AGAIN LATE FROM THE
OCEAN. NO SIGNIFICANT FLOODING IS ANTICIPATED THROUGH THE
DAY...BUT MINOR FLOODING IS STILL A CONCERN WITH A FEW POCKETS OF
HEAVY RAINS AND THE FULLY SATURATED GROUNDS FROM THE PAST SEVERAL
DAYS OF RAIN.

WHILE THERE COULD BE A LITTLE ELEVATED THUNDER...THE BETTER
CHANCES OF SURFACE BASED INSTABILITY WILL BE OUT OVER THE GULF
STREAM WHICH HEADS INTO OUR COASTAL WATERS LATE. IN
ADDITION...GIVEN THE OCCASIONAL HEAVY RAINS AND SEVERAL SITES
SHOWING LIGHT TO MODERATE FOG...WE HAVE ADDED PATCHY FOG TO THE
FORECAST.

TEMPS ARE NOT GOING MUCH OF ANYWHERE TODAY...MAYBE RISING A
COUPLE MORE DEGREES AT BEST. IN FACT WITH THE ONSET OF SOME COOLER
AIR FROM THE WEST AND NW THIS AFTERNOON AS THE STATIONARY FRONT
FORMS OVER THE ATLANTIC AND WINDS BECOMING NW AND NORTH...WE
COULD ACTUALLY START TO SEE TEMPS FALLING. FOR NOW WE HAVE AROUND
60 FAR INTERIOR GA TO THE LOWER AND MID 60S ELSEWHERE...A FAR CRY
FROM YESTERDAYS MAX TEMPS THAT WERE NEAR OR OVER 80 IN MANY SPOTS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
TONIGHT...STRENGTHENING LOW PRESSURE WILL MOVE UP THE FRONT AND
OFFSHORE OF THE AREA TONIGHT AS THE POWERFUL UPPER TROUGH BEGINS
TO PIVOT INTO A NEGATIVELY TILTED ORIENTATION ACROSS THE SOUTHEAST
STATES. IMPRESSIVE UPPER DYNAMICS COUPLED WITH STRONG
BAROCLINICITY ALONG THE WESTERN WALL OF THE GULF STREAM WILL
PROMOTE RAPID DEEPENING AS THE LOW APPROACHES THE NORTH CAROLINA
OUTER BANKS EARLY WEDNESDAY. EXPECT A BOUT OF WIDESPREAD MODERATE
TO HEAVY RAINS TO MOVE BECOME ENHANCED OVER THE AREA AS THE MOST
INTENSE DYNAMICS PUSH THROUGH THIS EVENING. HIGH END CATEGORICAL
POPS WILL BE DEPICTED FOR ALL AREAS WITH A MENTION OF RAIN
BECOMING HEAVY AT TIMES. FLOODING PROBLEMS ARE NOT CURRENTLY
ANTICIPATED...ALTHOUGH STORM TOTAL RAINFALL AMOUNTS OF 2-3 INCHES
WILL BE POSSIBLE AS THE STORM EXITS THE AREA. THE RAIN WILL BEGIN
TO TAPER DOWN FROM SOUTHWEST-NORTHEAST LATE AS THE LOW PROPAGATES
AWAY FROM THE AREA AND STRONG COLD AIR/DRY ADVECTION INITIATES IN
ITS WAKE. HOW QUICKLY THE RAIN ENDS IS STILL IN QUESTION...SO
HIGH GRIDDED POPS WILL BE MAINTAINED...DROPPING TO 70 PERCENT
SOUTHWEST TO 90 PERCENT NORTHEAST BY 12Z. FURTHER REFINEMENT IN
THE ENDING OF THE RAIN WILL BE NEEDED AS ADDITIONAL MODEL DATA ARE
RECEIVED. LOWS WILL RANGE FROM THE MID 40S ACROSS FAR INTERIOR
SOUTHEAST GEORGIA TO THE LOWER 50S ALONG THE LOWER SOUTH CAROLINA
COAST.

WEDNESDAY...LOW PRESSURE OFF THE CAROLINA COASTLINE WILL BE
RAPIDLY PULLING NORTH DURING THE MORNING HOURS...JUST AHEAD OF
ROBUST SHORTWAVE ENERGY SWEEPING THROUGH THE EAST COAST STATES
LATER IN THE DAY. EXPECT A RATHER NOTABLE GRADIENT IN
PRECIPITATION CHANCES AT DAYBREAK...WITH WIDESPREAD RAIN ACROSS
THE CHARLESTON TRI COUNTY AREA CLOSER TO THE DEPARTING LOW
SYSTEM...AND SCATTERED COVERAGE AT BEST FARTHER SOUTH TOWARD THE
ALTAMAHA RIVER. RAIN WILL BE STEADILY DECREASING FROM SOUTH TO
NORTH THROUGH THE MORNING HOURS...WITH DRY HIGH PRESSURE BUILDING
FROM THE WEST/SOUTHWEST IN THE WAKE OF THE COASTAL LOW. RAIN
SHOULD BE OUT OF THE AREA BY LATE AFTERNOON...AND EXPECT DRY
CONDITIONS TO PREVAIL INTO THE EVENING AND NIGHTTIME PERIOD.
TEMPERATURES ON WEDNESDAY WILL BE CONSIDERABLY COLDER THAN SEEN
IN THE PAST SEVERAL DAYS...AS BREEZY NORTHWEST FLOW AND COLD
ADVECTION SUPPRESS HIGHS IN THE LOW/MID 50S NORTH TO AROUND 60
DEGREES SOUTH. LOW TEMPERATURES WILL FALL INTO THE MID TO UPPER
30S AWAY FROM THE WARMER COASTLINE.

THURSDAY...WEAKENING SHORTWAVE ENERGY EMBEDDED WITHIN THE UPPER
TROUGH WILL PASS JUST TO THE NORTH DURING THE MORNING
HOURS...WHILE ANY ASSOCIATED PRECIPITATION REMAINS OUTSIDE OF THE
FORECAST AREA. A STRONGER CENTER OF HIGH PRESSURE WILL BUILD
TOWARD THE REGION FROM THE NORTHWEST...AND WITH THE AXIS OF THE
BROAD UPPER TROUGH MOVING ACROSS THE EAST COAST...A SLIGHT
DOWNSLOPE COMPONENT TO THE WIND WILL MITIGATE ANOTHER ROUND OF
COLD ADVECTION. WILL CONTINUE TO ADVERTISE DRY WEATHER AND CLEAR
SKIES ON THURSDAY...WITH HIGH TEMPERATURES PEAKING IN THE UPPER
50S TO AROUND 60 DEGREES. OVERNIGHT LOWS WILL FALL INTO THE LOW TO
MID 30S WITHIN WEAKENING SURFACE FLOW AND CLEAR SKIES.

FRIDAY...THE CENTER OF THE SURFACE HIGH WILL DESCEND OVER THE
SOUTHEAST STATES BY MIDDAY. COOLER NORTH WINDS AND HEIGHT FALLS
OVER THE REGION SUGGEST HIGH TEMPERATURES WILL ONLY REACH THE MID
TO UPPER 50S DESPITE ABUNDANT SUNSHINE.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
HIGH PRESSURE WILL STEADILY SLIP TOWARD THE COASTLINE AND OVER THE
ATLANTIC WATERS THIS WEEKEND INTO EARLY NEXT WEEK...WHILE FLAT
RIDGING DEVELOPS IN THE UPPER LEVELS. EXPECT A STEADILY MODERATING
AIR MASS AND WARMING TREND THROUGH THE PERIOD AS A RESULT. HIGH
TEMPERATURES ON SATURDAY WILL RANGE FROM THE UPPER 50S TO MID
60S...WITH TEMPERATURES PEAKING IN THE UPPER 60S TO AROUND 70
DEGREES BY MONDAY AND TUESDAY AFTERNOONS. LOW TEMPERATURES WILL
ALSO REFLECT THIS WARMING TREND...RANGING FROM THE LOW TO MID 30S
FRIDAY NIGHT...TO THE UPPER 40S BY MONDAY NIGHT. CONDITIONS APPEAR
DRY THROUGH THE EXTENDED PERIOD...AND WILL KEEP RAIN OUT OF THE
FORECAST.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
RAIN WITH EMBEDDED HEAVIER ELEMENTS AFFECT THE TERMINALS THROUGH
THE DAY AS WE REMAIN STUCK BETWEEN A DECAYING COLD FRONT INLAND
AND A DEVELOPING STATIONARY FRONT OVER THE ATLANTIC. THERE COULD
BE SOMEWHAT OF A LULL THIS AFTERNOON ...BEFORE ADDITIONAL MODERATE
TO HEAVY RAINS DOMINATE FOR MUCH OF THE NIGHT AS LOW PRESSURE
MOVES OFFSHORE ALONG THE STATIONARY FRONT. PREVAILING IFR/MVFR
WILL BE THE RULE THROUGH 26/12Z...BUT VFR WILL LIKELY PREVAIL FOR
A GOOD PORTION OF THE DAY OUTSIDE OF THE HEAVIER RAIN POCKETS.

EXTENDED AVIATION OUTLOOK...MODERATE TO HIGH CHANCES FOR IFR
CEILINGS INTO WEDNESDAY MORNING...WITH OCCASIONAL VSBY REDUCTIONS
TO IFR/MVFR DUE TO RAIN. VFR CONDITIONS WILL PREVAIL THEREAFTER.
BREEZY NORTHWEST WINDS EXPECTED ON WEDNESDAY.

&&

.MARINE...
TODAY...THE ATLANTIC RIDGE HAS FINALLY PULLED EAST OF THE WATERS
AS DEEP MID LATITUDE TROUGH IS SUPPORTING THE FORMATION OF A
NEARLY STATIONARY FRONT NOT FAR TO THE EAST. THIS CAN BE SEEN ON
BOTH SURFACE OBSERVATIONS WHERE WINDS OVER THE ATLANTIC ARE
MOSTLY NORTHERLY...AND ALSO ON RADAR WHERE WE FIND DEEP CONVECTION
FORMING OUT OVER THE GULF STREAM. FOR THE BULK OF THE DAY THE
GRADIENT WILL BE LAX ENOUGH TO SUPPORT WINDS NO HIGHER THAN 10
KT...EXCEPT SOME 15 KT ACROSS THE OUTER GA WATERS. SEAS WILL
BEHELD TO 5 FT OR LESS. A GOOD COVERAGE OF RAIN AND A FEW T-STORMS
WILL IMPACT THE MARINE COMMUNITY THROUGH THE DAY...SOME WITH HEAVY
RAINS AND LIGHTNING STRIKES...ALONG WITH SOME FOG TO REDUCE VSBYS
TO 1 TO 3 NM.

TONIGHT...HAZARDOUS CONDITIONS ARE EXPECTED TO DEVELOP OVER THE
WATERS LATE TONIGHT AS LOW PRESSURE MOVES JUST OFFSHORE. WINDS AND
SEAS WILL INCREASE DRAMATICALLY AFTER MIDNIGHT AS THE LOW PULLS
AWAY FROM THE REGION AND STRONG COLD AIR ADVECTION ENSUES. BOTH
THE NAM AND GFS SHOW A NASTY LOW-LEVEL WIND SIGNATURE DEVELOPING
ACROSS SOUTHEAST GEORGIA WHICH IS FORECAST TO SHOOT OVER THE
GEORGIA AND FAR SOUTHERN SOUTH CAROLINA COASTAL WATERS LATE
COINCIDENT WITH AN AREA OF INTENSE COLD AIR ADVECTION AND A LARGE
ISALLOBARIC RISE/FALL COUPLET. BOTH MODEL BOUNDARY LAYER WIND
WINDS SUPPORT FREQUENT GUSTS TO 35 KT GALES OVER THE COOLER SHELF
WATERS WITH GUSTS POTENTIALLY APPROACHING 45 KT OVER THE EASTERN
PORTIONS OF THE GEORGIA OFFSHORE LEG CLOSER TO THE WARMER WATERS
OF THE GULF STREAM. THE DURATION OF ANY POTENTIAL GALES LOOKS TO
BE ABOUT 5-7 HOURS. PER COLLABORATION WITH WFO JAX AND THE OCEAN
PREDICTION CENTER...A GALE WATCH WILL BE ISSUED FOR BOTH GEORGIA
MARINE ZONES AND THE BEAUFORT COUNTY COASTAL WATERS. FARTHER
NORTH...THE LOW-LEVEL WIND SIGNATURE LOOKS CONSIDERABLY WEAKER SO
A SMALL CRAFT ADVISORY WILL BE ISSUED FOR THE CHARLESTON COUNTY
WATERS. ATTM IT APPEARS CONDITIONS WILL REMAIN JUST SHY OF
ADVISORY CRITERIA IN THE CHARLESTON HARBOR.

WEDNESDAY THROUGH SATURDAY...A COASTAL LOW PRESSURE SYSTEM RAPIDLY
PULLING TO THE NORTHEAST WILL MAINTAIN HAZARDOUS MARINE CONDITIONS
INTO WEDNESDAY MORNING...DUE TO THE ASSOCIATED TIGHT PRESSURE
GRADIENT AND COLD ADVECTION MIXING OVER THE WATERS. GALE
CONDITIONS COULD BE ONGOING IN THE OUTER GEORGIA WATERS WEDNESDAY
MORNING...WITH SOLID SMALL CRAFT ADVISORY WINDS IN THE NEARSHORE
MARINE ZONES. THERE COULD BE A BRIEF BREAK IN ADVISORY CONDITIONS
WEDNESDAY AFTERNOON/EVENING...BEFORE STRONG HIGH PRESSURE
BUILDING FROM THE NORTHWEST REINFORCES THE GRADIENT AND COLD
ADVECTION. SMALL CRAFT ADVISORIES COULD THEN BE NEEDED AGAIN FOR
PORTIONS OF THE MARINE ZONES THURSDAY. CONDITIONS WILL THEN
IMPROVE FOR FRIDAY AND SATURDAY...AS THE SURFACE HIGH SHIFTS
TOWARD THE WATERS AND THE GRADIENT RELAXES.

&&

.CLIMATE...
PRECIPITATION RECORDS FOR 25 NOVEMBER...
KCHS...1.87 INCHES SET IN 1972.
KCXM...3.52 INCHES SET IN 1899.
KSAV...2.01 INCHES SET IN 1899.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...GALE WATCH FROM LATE TONIGHT THROUGH WEDNESDAY MORNING FOR
     AMZ352-354-374.
     SMALL CRAFT ADVISORY FROM 4 AM TO 10 AM EST WEDNESDAY FOR
     AMZ350.

&&

$$

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






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