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Area Forecast Discussion

912
FXUS62 KCHS 262328
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
628 PM EST MON JAN 26 2015

.SYNOPSIS...
LOW PRESSURE WILL RAPIDLY INTENSITY AS IT LIFTS NORTHWARD OFF THE
MID-ATLANTIC COAST TONIGHT. A REINFORCING COLD FRONT WILL MOVE
THROUGH LATE TUESDAY INTO TUESDAY NIGHT...FOLLOWED BY HIGH PRESSURE
THROUGH MID WEEK. A COLD FRONT WILL PUSH ACROSS THE AREA
FRIDAY...WITH A RETURN OF HIGH PRESSURE ON SATURDAY. A STORM SYSTEM
WILL THEN AFFECT THE AREA LATE IN THE WEEKEND INTO EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
TONIGHT...A HIGHLY AMPLIFIED LARGE SCALE PATTERN WILL PREVAIL
ALOFT WITH A DEEP TROUGH OVER THE EAST. A ROBUST SHORT WAVE OFF
THE MID ATLANTIC WILL BE RESPONSIBLE FOR TRIGGERING INTENSE
CYCLOGENESIS OFF CAPE HATTERAS AND THE DELMARVA AT THE
SURFACE...THE ANTICIPATED BLIZZARD FOR PARTS OF THE NORTH STATES.

THERE IS A WEAKER...BUT STILL FAIRLY DECENT SHORT WAVE MOVING
THROUGH THIS EVENING WHICH WILL STILL PRODUCE A LITTLE LIGHT
SHOWER ACTIVITY OVER CHARLESTON AND BERKELEY COUNTIES UNTIL ABOUT
8 PM...WITH DRY CONDITIONS TO PREVAIL ELSEWHERE.

THE LARGE CYCLONIC FLOW AROUND THE ATLANTIC STORM WILL EXTEND
ACROSS THE LOCAL DISTRICT THROUGH THE NIGHT...WHICH PREVENTS HIGH
PRESSURE IN THE GREAT PLAINS FROM MAKING MUCH EASTWARD PROGRESS.
THIS IN TURN LIMITS HOW MUCH DECREASE IN CLOUDINESS IS ABLE TO
OCCUR. A FAIRLY LARGE CLEAR SWATH AS FORMED OVER SOUTHERN
CHARLESTON...MUCH OF COLLETON AND PARTS OF ALLENDALE AND HAMPTON
COUNTIES. NOT YET SURE IF THIS IS ONLY TEMPORARY OR IF OTHER
CLOUDS WILL FILL BE BACK. EVEN SO...THE TREND SHOULD BE FOR A MORE
PRONOUNCED CLEARING TO DEVELOP OVER THE REGION LATE THIS EVENING
AND/OR OVERNIGHT AS THE SYNOPTIC FLOW VEERS NW AND THE DOWNSLOPE
OFF THE MOUNTAINS ERODES THE STRATOCUMULUS CLOUD COVER.

A TIGHT GRADIENT WILL PERSIST BETWEEN THE DISTANT LOW AND THE MID-
COUNTY RIDGE...KEEPING THINGS PRETTY WELL MIXED. BUT THE CONSTANT
FEED OF COLDER AIR FROM THE WEST AND NW WILL SEND TEMPS DOWN TO
THE LOWER AND MIDDLE 30S MOST PLACES BY MORNING...WITH A FEW UPPER
30S AT THE COAST. COMBINED WITH THE WINDS IT WILL YIELD WIND
CHILLS AS COLD AS THE MID AND UPPER 20S CLOSER TO DAYBREAK TUESDAY.

LAKE WINDS...COLD ADVECTION ACROSS THE WARMER LAKE MOULTRIE WATERS
WILL MIX EFFICIENTLY TONIGHT...AS WEST AND NORTHWEST WINDS REACH
20 TO 25 KT AND WAVES ARE 1 TO 2 FT. THUS OUR LAKE WIND ADVISORY
REMAINS IN FORCE.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
TUESDAY AND TUESDAY NIGHT...THE REGION WILL REMAIN ALONG THE
SOUTHWEST PERIPHERY OF A DEEP...VERTICALLY STACKED LOW PRESSURE
SYSTEM LOCATED OFF THE NEW ENGLAND COAST. MEANWHILE AT THE
SURFACE...A REINFORCING COLD FRONT WILL DROP ACROSS THE AREA LATE
TUESDAY INTO EARLY TUESDAY NIGHT. GIVEN A DRY WEST-NORTHWEST FLOW
AHEAD OF THE FRONT...ITS PASSAGE WILL BE RAIN-FREE. TEMPERATURES
WILL REACH HIGHS IN THE LOWER TO MID 50S ACROSS THE AREA. COLD AIR
ADVECTION AND CLEARING SKIES BEHIND THE FRONT WILL RESULT IN A COOL
NIGHT WITH LOWS AROUND 30 OR IN THE LOWER 30S AWAY FROM THE
IMMEDIATE COAST.

WEDNESDAY AND THURSDAY...THE DEEP UPPER TROUGH WILL SHIFT OFF THE
EAST COAST ON WEDNESDAY...WITH MORE OF A ZONAL FLOW DEVELOPING
THROUGH THURSDAY. SURFACE HIGH PRESSURE WILL BUILD FROM THE WEST ON
WEDNESDAY...SETTLE OVER THE REGION WEDNESDAY NIGHT...THEN SHIFT
OFFSHORE ON THURSDAY. SUBSIDENCE AND A LACK OF DEEP MOISTURE WILL
KEEP CONDITIONS RAIN-FREE. TEMPERATURES WEDNESDAY WILL REMAIN
UNSEASONABLY COOL WITH HIGHS IN THE LOWER TO MID 50S AND NIGHTTIME
LOWS IN THE UPPER 20S TO LOWER 30S AWAY FROM THE COAST. TEMPERATURES
WILL BEGIN TO MODERATE INTO THE UPPER 50S AND LOWER 60S FOR HIGHS
THURSDAY AS THE HIGH SHIFTS OFFSHORE AND A SOUTHERLY RETURN FLOW
DEVELOPS.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AN AREA OF LOW PRESSURE WILL ADVANCE OVER THE NORTHEASTERN UNITED
STATES WITH A TRAILING COLD FRONT THAT PUSHES THROUGH THE AREA
THURSDAY NIGHT INTO EARLY FRIDAY. DEEP MOISTURE WILL BE LACKING
DURING THE TIME OF FROPA...BUT ISOLATED SHOWERS APPEAR POSSIBLE
MAINLY THURSDAY NIGHT. FAIRLY DRY AND SLIGHTLY BELOW NORMAL TEMPS
ARE THEN ANTICIPATED ON SATURDAY AS SFC HIGH PRESSURE BUILDS FROM
THE NORTH. A STORM SYSTEM APPEARS TO SPREAD CONSIDERABLE MOISTURE
INTO THE REGION LATE IN THE WEEKEND INTO EARLY NEXT WEEK...BRINGING
THE NEXT CHANCE FOR SHOWERS TO THE AREA.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
VFR CEILINGS EXPECTED THROUGH TONIGHT...ALTHOUGH PERIODS OF
SCATTERED CLOUDS COULD DEVELOP PRIOR TO TUESDAY MORNING. MODEL
SOUNDINGS SUGGEST A LOW PROBABILITY MVFR CEILINGS LATER
TONIGHT/EARLY TUESDAY. WESTERLY WINDS WILL GUST 25-30
KNOTS...STRONGEST AT KSAV...INTO EARLY EVENING.

EXTENDED AVIATION OUTLOOK...VFR CONDITIONS ARE EXPECTED TO PREVAIL.

&&

.MARINE...
TONIGHT...NASTY MARINE CONDITIONS WILL OCCUR AS LOW PRESSURE OFF
THE DELMARVA RAPIDLY INTENSIFIES AS IT LIFTS NE. A TIGHT
GRADIENT...STEADY ISALLOBARIC PRESSURE RISES AND AMPLE MIXING OF
THE 30-40 KT GEOSTROPHIC WINDS AT 1000 MB WILL SUPPORT SOLID SMALL
CRAFT ADVISORIES FOR ALL BUT AMZ374...WHERE WE HAVE A GALE WARNING
IN EFFECT. WEST AND NW WINDS WILL AVERAGE 20 TO 25 KT...WITH GUSTS
OF 30 KT WITHIN 20 NM OF SHORE...25 TO 30 KT WITH GUSTS OF 35 OR
40 KT OVER THE OUTER GA WATERS...AND 15 TO 25 KT IN CHARLESTON
HARBOR. SEAS WILL RANGE FROM 3 FT NEAR THE IMMEDIATE COAST TO 6 OR
7 FT NEAR 20 NM OUT AND 8 TO 9 FT 50-60 NM OFF THE COAST. WAVES
WILL BE UP TO 2 FT IN CHARLESTON HARBOR.

TUESDAY...LOW PRESSURE WILL CONTINUE TO DEEPEN WHILE LIFTING
NORTHEAST ALONG THE NEW ENGLAND COAST. ALONG THE SOUTHERN PERIPHERY
OF THE LOW...A TIGHT SURFACE PRESSURE GRADIENT WILL MAINTAIN
ELEVATED OFFSHORE WINDS ACROSS THE WATERS IN THE MORNING...WITH
SPEEDS GRADUALLY DIMINISHING IN THE AFTERNOON AS THE GRADIENT
WEAKENS. SMALL CRAFT ADVISORIES FOR CHARLESTON HARBOR AND THE NEAR
SHORE WATERS WILL THEREFORE BE ALLOWED TO EXPIRE BY LATE
MORNING...WITH CONDITIONS FALLING BELOW SMALL CRAFT ADVISORY
CRITERIA IN THE OUTER GEORGIA WATERS DURING THE AFTERNOON. A
REINFORCING COLD FRONT WILL THEN DROP THROUGH LATE TUESDAY INTO
TUESDAY NIGHT...WITH A NORTHERLY SURGE DEVELOPING IN ITS WAKE. THERE
IS A SMALL POTENTIAL FOR WINDS TO BRIEFLY REACH BACK TO SMALL CRAFT
ADVISORY LEVELS INTO WEDNESDAY MORNING.

WEDNESDAY AFTERNOON THROUGH SUNDAY...HIGH PRESSURE WILL BUILD INTO
THE REGION THROUGH THURSDAY. A COLD FRONT WILL THEN SHIFT
OVER THE AREA THURSDAY NIGHT INTO EARLY FRIDAY...SLIGHTLY ENHANCING
AND CHANGING A SOUTHERLY WIND TO NORTHERLY AS HIGH PRESSURE BUILDS
IN BEHIND IT. A WEAK COASTAL TROUGH COULD DEVELOP OFFSHORE ON
SATURDAY...WITH A STORM SYSTEM EXPECTED TO AFFECT THE AREA LATE IN
THE WEEKEND. WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT
ADVISORY CRITERIA THROUGH THE PERIOD.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...LAKE WIND ADVISORY UNTIL 6 AM EST TUESDAY FOR SCZ045.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EST TUESDAY FOR AMZ330-350-
     352-354.
     GALE WARNING UNTIL 7 AM EST TUESDAY FOR AMZ374.

&&

$$

NEAR TERM...
SHORT TERM...JAQ
LONG TERM...DPB
AVIATION...
MARINE...






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