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000
FXUS62 KCHS 260151
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
951 PM EDT FRI JUL 25 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 WILL APPROACH AND CROSS THE REGION LATE MONDAY
AND BECOME STATIONARY SOUTH AND SOUTHEAST OF THE AREA THROUGH THE
MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
THE BULK OF THE CONVECTION LATE MID-EVENING IS FOCUSED ALONG OR
JUST NORTH OF THE SAVANNAH RIVER. SHOWERS AND THUNDERSTORMS WILL
CONTINUE THROUGH THE EVENING...VERY POSSIBLY TRAINING OVER THE
VERY SAME AREAS AND ALSO EXPANDING A BIT FARTHER INTO SOUTHEAST
GEORGIA. THE FORECAST HAS BEEN UPDATED TO REFLECT THE LATEST
TRENDS. GIVEN THE SLOW STORM MOTIONS AND TRAINING ALONG VARIOUS
BOUNDARIES...HEAVY RAINFALL AND THE POTENTIAL FOR LOCALIZED
FLOODING WILL CONTINUE. STILL COULD NOT RULE OUT AN ISOLATED
STRONG/SEVERE THUNDERSTORM...BUT THE GREATEST CONCERN REMAINS THE
HEAVY RAINFALL AND EXCESSIVE LIGHTNING THAT THESE STORMS ARE
PRODUCING. MOISTURE CONVERGENCE AND WEAK UPPER DIFLUENCE SHOULD
DIMINISH AFTER MIDNIGHT AND WE EXPECT CONVECTIVE CONVERAGE TO
DECREASE IN BOTH COVERAGE AND INTENSITY ALTHOUGH SHOWERS AND TSTMS
COULD LINGER DEEPER INTO THE NIGHT AT SOME LOCATIONS IN SE SOUTH
CAROLINA.

TEMPERATURES HAVE BEEN GREATLY IMPACTED BY THUNDERSTORM ACTIVITY...
WITH RAIN-COOLED AREAS SEEING TEMPERATURES FALL INTO THE LOWER TO
MID 70S...WHICH COULD VERY WELL BE THE LOW TEMPERATURE FOR THE
NIGHT IN SOME SPOTS. TEMPERATURES COULD REBOUND A FEW
DEGREES...BUT OVERALL LOWS IN THE LOWER TO MID 70S ARE EXPECTED
ACROSS THE AREA.

ALTHOUGH THE LOW LEVELS WILL BE QUITE WET WHERE RAINFALL HAS
OCCURRED...THERE IS A LOT OF UNCERTAINTY REGARDING CLOUD COVER
AND SUBSEQUENT FOG POTENTIAL. WILL THUS HOLD OFF ON MENTIONING FOG
IN THE FORECAST AND ALLOW SUBSEQUENT ISSUANCES TO ADDRESS THE
POTENTIAL.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
SATURDAY AND SATURDAY NIGHT...A MID AND UPPER LEVEL TROUGH WILL
DAMPEN AS ITS AXIS GRADUALLY SHIFTS EAST OF THE AREA AND RIDGING
CENTERED OVER THE SOUTHWEST AND SOUTHERN PLAINS BUILDS EASTWARD. AT
THE SURFACE...ATLANTIC HIGH PRESSURE WILL PREVAIL AS A TROUGH OF LOW
PRESSURE LINGERS INLAND. A WESTERLY FLOW ALOFT WILL REDUCE MOISTURE
AND GRADUAL WARMING/RISING HEIGHTS ALOFT SHOULD AID IN SUPPRESSING
CONVECTION. HOWEVER...WILL CARRY A SLIGHT CHANCE OF SHOWERS/
THUNDERSTORMS DURING THE AFTERNOON/EARLY EVENING AS A FEW ISOLATED
THUNDERSTORMS COULD DEVELOP ALONG ANY LINGERING BOUNDARIES INCLUDING
THE SEA BREEZE. DOWNSLOPE FLOW SHOULD ALLOW TEMPERATURES TO WARM TO
THE MID 90S AWAY FROM THE IMMEDIATE COAST DURING THE AFTERNOON...
WITH LOWS IN THE MID 70S AT NIGHT.

SUNDAY AND SUNDAY NIGHT...MID AND UPPER LEVEL RIDGING WILL CONTINUE
TO EXPAND EASTWARD ACROSS THE REGION FROM THE SOUTHWEST/SOUTHERN
PLAINS. STRONG CAPPING AND A DRIER WESTERLY FLOW ALOFT COULD VERY
WELL RESULT IN RAIN-FREE CONDITIONS...HOWEVER WILL MAINTAIN A SLIGHT
CHANCE OF SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON UNTIL THE
DRIER TREND BECOMES MORE CERTAIN. TEMPERATURES WILL CONTINUE ON THE
WARMING TREND GIVEN DOWNSLOPE FLOW AND RISING HEIGHTS ALOFT...WITH
HIGHS FORECAST TO BE IN THE MID TO UPPER 90S INLAND FROM THE COAST.
LOWS AT NIGHT WILL BE MILD...GENERALLY IN THE MID TO UPPER 70S.

MONDAY...A MORE AMPLIFIED MID AND UPPER LEVEL PATTERN WILL DEVELOP
AS A TROUGH EXPANDS OVER THE EASTERN UNITED STATES. THIS WILL DRIVE
A COLD FRONT AT THE SURFACE TOWARD THE AREA FROM THE NORTHWEST. AN
AXIS OF DEEPER MOISTURE WILL SPREAD OVER THE AREA AHEAD OF THE
FRONT...AND THERE IS A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS
DURING THE AFTERNOON AND EVENING...ESPECIALLY ACROSS
INLAND/NORTHWEST PORTIONS OF THE AREA GIVEN THE ORIENTATION/TIMING
OF THE FRONT. STRENGTHENING SOUTHWEST WINDS IN THE LOW LEVELS OF THE
ATMOSPHERE WILL RESULT IN RATHER MOIST CONDITIONS...WITH DEWPOINTS
SURGING INTO THE LOWER AND MID 70S. THIS MOIST AIR MASS AND STRONG
DIURNAL HEATING WILL RESULT IN A RATHER UNSTABLE AIR MASS WITH SB
CAPE VALUES RISING TO 2000-3000 J/KG...LI/S DOWN TO -7 OR -8C AND
STEEP MID LEVEL LAPSE RATES. IN ADDITION...FALLING HEIGHTS/COOLING
ALOFT AND AN INCREASE OF DEEP LAYER SHEAR COULD SUPPORT STRONG TO
SEVERE THUNDERSTORMS ACROSS THE AREA. DOWNSLOPE FLOW AND STRONG
COMPRESSIONAL HEATING WILL LIKELY RESULT IN HIGHS IN THE UPPER 90S
INLAND FROM THE IMMEDIATE COAST...UNLESS CONVECTION DEVELOPS EARLIER
THAN ANTICIPATED. GIVEN THE HIGH DEWPOINTS...HEAT INDEX VALUES COULD
REACH UPWARDS OF AROUND 110 DEGREES IN SOME AREAS. SINCE THIS IS OUR
CRITERIA FOR A HEAT ADVISORY...HAVE ADDED MENTION TO THE HAZARDOUS
WEATHER OUTLOOK.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
THE COLD FRONT IS PROGGED TO MOVE THROUGH THE AREA MONDAY NIGHT AND
BECOME NEARLY STATIONARY TO THE EAST AND SOUTH. BEHIND THE
FRONT...EXPECT A NOTICEABLE AIR MASS DIFFERENCE AS HEIGHTS FALL
OVERHEAD WITHIN THE AMPLIFYING EASTERN CONUS TROUGH. THIS SETUP WILL
KEEP TEMPERATURES 2-4 DEGREES CLIMO THROUGH THE END OF THE WEEK. THE
BEST CHANCE FOR RAIN...AND RESULTING HIGHEST POPS...WILL BE IN THE
MONDAY NIGHT TIME PERIOD ASSOCIATED WITH THE FRONT.
THEREAFTER...POPS WILL BECOME MORE DIURNAL IN NATURE AS THE LOW
LEVEL FLOW TURNS MORE EAST TO NORTHEAST WITH TIME.

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
KCHS...SOME SHOWERS COULD IMPACT THE TERMINAL THROUGH ABOUT
03Z...BUT IMPACTS SHOULD BE MINIMAL. GIVEN THE EARLIER
RAINFALL...THERE IS THE POTENTIAL FOR SOME FOG TO DEVELOP TOWARD
DAYBREAK AND HAVE INCLUDED A TEMPO GROUP FOR MVFR CONDITIONS
DURING THE 09-12Z TIME PERIOD. ISOLATED CONVECTION IS EXPECTED
SATURDAY AFTERNOON...BUT COVERAGE SHOULD BE TOO LIMITED TO INCLUDE
MENTION IN THE FORECAST AT THIS TIME.

KSAV...VICINITY THUNDERSTORMS ARE IN THE FORECAST THROUGH
04Z...BUT A DIRECT IMPACT IS CERTAINLY POSSIBLE AT THE TERMINAL
AND COULD RESULT IN FLIGHT RESTRICTIONS. HAVE NOT INCLUDED ANY
MENTION OF FOG...BUT IF SUFFICIENT RAIN OCCURS AT THE TERMINAL
THAN THE POTENTIAL FOR FOG WILL INCREASE TOWARD DAYBREAK. ISOLATED
CONVECTION IS EXPECTED SATURDAY AFTERNOON...BUT COVERAGE SHOULD
BE TOO LIMITED TO INCLUDE MENTION IN THE FORECAST AT THIS TIME.

EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. A COLD FRONT IS EXPECTED
TO MOVE THROUGH THE AREA LATE MONDAY. BRIEF CEILING AND VISIBILITY
REDUCTIONS MAY BE POSSIBLE WITH THUNDERSTORMS THAT DEVELOP IN THE
EVENING HOURS.

&&

.MARINE...
TONIGHT...WINDS HAVE SURGED UPWARDS OF 15-20 KT WITH HIGHER GUSTS OVER
THE GEORGIA COASTAL WATERS THIS EVENING...BUT WILL NOT ISSUE A SMALL
CRAFT ADVISORY AS THESE CONDITIONS SHOULD BE RATHER SHORT LIVED. 8PM
PILOT BOAT OBSERVATIONS SUGGEST FORECAST IS IN GOOD SHAPE THIS EVENING.
OVERALL...EXPECT SOUTH/SOUTHWEST WINDS 15 KT OR LESS...VEERING TO
THE SOUTHWEST/WEST LATE AS LAND BREEZE CIRCULATIONS ARRIVE.

SATURDAY THROUGH TUESDAY...THE FIRST PORTION OF THE FORECAST PERIOD
WILL FEATURE HIGH PRESSURE TO THE EAST AND AN INLAND TROUGH OF LOW
PRESSURE. THIS WILL PROMOTE A MODEST SOUTHWEST FLOW THROUGH SUNDAY.
THEN SUNDAY NIGHT ONWARD THE PRESSURE GRADIENT WILL TIGHTEN IN
RESPONSE TO AN APPROACHING COLD FRONT. THIS WILL RESULT IN WINDS
INCREASING INTO THE 15-20 KT RANGE...AND PERHAPS EVEN MARGINALLY
SUPPORTIVE OF SMALL CRAFT ADVISORIES FOR PORTIONS OF THE WATERS
MONDAY AND MONDAY NIGHT. THE GRADIENT AND RESULTING WINDS WILL THEN
DECREASE ON TUESDAY.

&&

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

&&

$$

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