Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 301636
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1236 PM EDT THU JUL 30 2015

.SYNOPSIS...
LOW PRESSURE REMAINS OFF THE SOUTHEAST COAST. A COLD FRONT WILL MOVE
INTO THE AREA FRIDAY AND STALL OVER THE WEEKEND BEFORE DISSIPATING
MONDAY. BERMUDA HIGH PRESSURE WILL EXPAND WEST TUESDAY AND WEDNESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 AM THURSDAY...NO SIGNIFICANT CHANGES HAVE BEEN MADE TO
FORECAST HIGH TEMPERATURES OR DEWPOINTS...THE COMBINATION OF WHICH
YIELD HEAT INDICES RIGHT AT THE DOORSTEP OF HEAT ADVISORY CRITERIA
ACROSS PARTS OF SOUTH CAROLINA. SEEING THE DEWPOINT FALL INTO THE
60S ALREADY IN FLORENCE BOLSTERS CONFIDENCE WE WILL REMAIN BELOW 105
DEGREE HEAT INDEX VALUES. DESPITE PLENTY OF DRY AIR ABOVE 850
MB...RICH MOISTURE BELOW THAT LEVEL HAS GENERATED A VERY HEALTHY
CUMULUS FIELD FROM SOUTHPORT ACROSS WILMINGTON TO JACKSONVILLE NC.
WHILE AN ISOLATED SHOWER/SPRINKLE IS POSSIBLE ACROSS THE SURF
CITY/HOLLY SHELTER SWAMP AREA OF PENDER COUNTY I THINK DRY AIR
SHOULD PREVENT ANYTHING MORE. I STILL LOOK FOR ISOLATED
SHOWERS/STORMS LATE IN THE DAY NEAR/WEST OF I-95 WHERE THE DRY MID-
LEVEL AIR SHOULD BE MOISTENING THROUGH THE DAY. DISCUSSION FROM 1030
AM FOLLOWS...

LOW PRESSURE CENTERED ROUGHLY 300 MILES EAST OF SAVANNAH HAS A NICE
SWIRL IN VISIBLE SATELLITE IMAGERY. BUOY 41002 RECENTLY GUSTED TO 37
KNOTS AS A CONVECTIVE OUTFLOW BOUNDARY PASSED ACROSS IT. ASIDE FROM
NORTHERLY FLOW AROUND THE PERIPHERY OF THIS LOW DRAGGING SOME DRIER
AIR SOUTHWARD...THIS LOW WILL HAVE ALMOST NO IMPACT ON OUR WEATHER
TODAY ACROSS THE EASTERN CAROLINAS.

FOR OUR AREA IT SHOULD BE A FAIRLY TYPICAL SUMMER DAY WITH THE
EXCEPTION OF 850 MB TEMPS NEAR +20C...A COUPLE DEGREES ABOVE NORMAL.
WITH PLENTY OF SUNSHINE THIS SHOULD PUSH HIGHS TO 92-98 DEGREES
INLAND FROM THE BEACHES TODAY...3 TO 8 DEGREES ABOVE NORMAL.
DEWPOINTS SHOULD MIX DOWN TO 70-72 THIS AFTERNOON AWAY FROM THE
COAST...AND THIS COULD PUSH HEAT INDICES VERY CLOSE TO 105 DEGREES.
I HAVE UPDATED THE HAZARDOUS WEATHER OUTLOOK FOR HIGHLIGHT NEAR-
ADVISORY CRITERIA FOR HEAT INDEX ACROSS INTERIOR SOUTH CAROLINA AND
ROBESON COUNTY NC.

CONVECTIVE POTENTIAL APPEARS QUITE LIMITED TODAY AS THERE IS A SLUG
OF VERY DRY AIR IN THE 850-700 MB LAYER ALONG THE COAST. USING MEAN
RH <70% THROUGH THIS LAYER AS A GUIDE I HAVE REMOVED ANY MENTION OF
PRECIPITATION TODAY EAST OF I-95...WITH ONLY A 20 POP REMAINING
ACROSS THE SANDHILLS/INTERIOR PEE DEE REGION. THE LATEST FEW HRRR
RUNS ALSO GENERATE NO PRECIPITATION EAST OF I-95 TODAY.

A COLD FRONT CURRENTLY ACROSS WEST VIRGINIA AND EASTERN TENNESSEE
WILL MOVE INTO THE CAROLINAS TONIGHT AND WILL REACH I-95 BEFORE
DAYBREAK. INCREASING CLOUDS AND MOISTURE POOLING NEAR THE FRONT
SHOULD HELP KEEP LOWS QUITE WARM...72-76 MOST AREAS.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...WEAK COLD FRONT MOVING INTO THE AREA AT
THE START OF PERIOD WILL STALL NEAR THE COAST...LINGERING IN THE
AREA THROUGH THE END OF THE PERIOD. FRONT ARRIVES WITH AN
ABUNDANCE OF DEEP MOISTURE AND LOW LEVEL CONVERGENCE BUT TIMING IS
RATHER EARLY AS FAR AS SURFACE BASED INSTABILITY IS CONCERNED.
FRONT AND DEEP MOISTURE BRIEFLY STALL IN THE AREA FRI AND IT
SHOULD ONLY BE A MATTER OF WAITING UNTIL EARLY AFTERNOON BEFORE
HEATING CAN GENERATE LOW LEVEL INSTABILITY...LEADING TO
CONVECTION. PREVIOUSLY IT APPEARED THE DEEPER MOISTURE WOULD
LINGER OVER THE AREA INTO SAT BUT WITH THE 00Z GUIDANCE THERE HAS
BEEN AN INCREASE IN THE RATE AT WHICH DRY AIR TO THE NORTHWEST
MOVES INTO THE AREA.

FORECAST SOUNDINGS NOW SHOW DRY AIR MOVING OVER WESTERN COUNTIES BY
EARLY TO MID AFTERNOON FRI AND TO THE COAST BY SAT MORNING. THE DROP
IN PRECIPITABLE WATER IS RATHER SIGNIFICANT WITH VALUES DROPPING
FROM OVER 2 INCHES FRI MORNING TO AROUND 1.5 INCH LATE FRI NIGHT OR
EARLY SAT. IF THE LATEST GUIDANCE IS CORRECT THERE MAY BE LITTLE IN
THE WAY OF PRECIP ALONG AND WEST OF I-95 WITH A RAPID INCREASE IN
PRECIP CHANCES EAST OF I-95. THE PRESENCE OF DRY AIR SAT ALONG WITH
A LACK OF ANY MID LEVEL DYNAMICS AND ONLY A WEAKENING SURFACE
BOUNDARY IN PLACE ALSO PUTS HEFTY PRECIP CHANCES SAT IN DOUBT. WILL
MAINTAIN INHERITED CHC POP BUT DID TREND VALUES DOWN A LITTLE BIT.
TEMPERATURES WILL BE NEAR TO SLIGHTLY ABOVE CLIMO THROUGH THE
PERIOD.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...DISSIPATING FRONT WILL LINGER IN THE AREA
INTO THE MIDDLE OF NEXT WEEK...SLOWLY BECOMING A WASHED OUT
SURFACE TROUGH BY TUE/WED. THE EVOLUTION OF THE MID LEVEL PATTERN
WILL DETERMINE HOW UNSETTLED NEXT WEEKS WEATHER IS. BY SUN MORNING
FAIRLY BROAD 5H TROUGH WILL BE OVER THE EAST COAST. THE BIG
QUESTION REMAINS HOW CLOSE WILL THE TROUGH AXIS BE TO THE COAST.
THIS WILL DETERMINE IF THE DEEP MOISTURE WILL LINGER OVER THE AREA
OR OFF THE COAST. ALTHOUGH THE MEDIUM RANGE GUIDANCE AND THE
ENSEMBLES DO NOT PROVIDE A CLEAR PICTURE IT SEEMS THE TRENDS ARE
TO SHIFT THE DEEP MOISTURE OFF THE COAST DURING THE SECOND HALF OF
THE WEEKEND. THIS WOULD LEAD TO SOME DRYING FOR NEXT WEEK AND A
REDUCTION IN PRECIP CHANCES. GIVEN THE AMOUNT OF UNCERTAINTY AND
THE POTENTIAL FOR MOISTURE TO LINGER CLOSER TO THE COAST WILL
MAINTAIN INHERITED CHC POP DURING THE FIRST HALF OF THE PERIOD.

TROUGH LIFTS OUT EARLY TUE...ALLOWING THE 5H RIDGE TO THE WEST AN
OPPORTUNITY TO EXPAND EAST. THIS WILL HAPPEN GRADUALLY AND THE
FLOW ALOFT WILL BE ON THE WEAK SIDE WITH LITTLE FORCING. WILL
CARRY SLIGHT CHC TO CHC POP FOR THE END OF THE PERIOD...MAINLY FOR
DIURNAL CONVECTION ON THE SEA BREEZE AND PIEDMONT TROUGH BUT
INCREASING SUBSIDENCE WILL LEAD TO DECREASING PRECIP CHANCES AS
THE PERIOD ENDS.

TEMPERATURES NEAR TO SLIGHTLY ABOVE CLIMO EARLY IN THE PERIOD
WILL CLIMB ABOVE CLIMO TUE/WED AS SURFACE AND MID LEVEL RIDGING
EXPAND AND SUBSIDENCE STARTS TO DEVELOP.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 18Z...LFC`S COMING DOWN NORTH OF THE REGION. MAY SEE
CONVECTION IN PENDER AND NEW HANOVER COUNTIES THIS AFTERNOON...BUT
WILL STICK  WITH VCSH DUE TO COVERAGE AND INTENSITY. MAINLY AN EAST
NORTHEAST WIND THIS AFTERNOON ALONG THE COAST...LIGHT INLAND.
TONIGHT...THE NAM WANTS TO KEEP CONVECTION GOING AS THE FRONT LAYS
OVER THE CWA. DUE TO LACK OF FORCING...SHOULD SEE CONVECTION ENDING
FOR DIURNAL REASONS AFTER 02Z WITH ONLY ISOLATED ACTIVITY OVERNIGHT.
FRIDAY...EXPECT CONVECTION  TO FIRE FAIRLY EARLY...MAINLY OVER THE
EASTERN HALF OF THE REGION. POST FRONTAL LIGHT NORTHERLY FLOW IS
FORECAST.

EXTENDED OUTLOOK...PREDOMINANTLY VFR THROUGH THE PERIOD WITH A
SLIGHT CHANCE AFTERNOON SHRA/TSRA. BEST CHANCE SHRA/TSRA FRIDAY AND
SATURDAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 AM THURSDAY...LOW PRESSURE CENTERED ROUGHLY 300 MILES
EAST OF SAVANNAH HAS A NICE SWIRL IN VISIBLE SATELLITE IMAGERY. BUOY
41002 RECENTLY GUSTED TO 37 KNOTS AS A CONVECTIVE OUTFLOW BOUNDARY
PASSED ACROSS IT. ASIDE FROM TWO ENHANCED SWELL SETS (7 SECONDS FROM
THE SOUTH AND 10 SECONDS FROM THE SOUTHEAST) THIS LOW WILL HAVE
ALMOST NO IMPACT ON OUR WEATHER TODAY OR TONIGHT ACROSS THE EASTERN
CAROLINAS. LIGHT NORTHEAST WIND THIS MORNING WILL SHIFT ONSHORE THIS
AFTERNOON WITH THE SEABREEZE...WITH NEARSHORE WINDS INCREASING TO 10-
12 KNOTS. SEAS CURRENTLY 2-3 FEET MAINLY IN SWELL WILL DEVELOP AN
INCREASING WIND CHOP COMPONENT ON TOP THIS AFTERNOON.

BY TONIGHT A COLD FRONT CURRENTLY ACROSS WEST VIRGINIA AND EASTERN
TENNESSEE WILL APPROACH THE AREA. SOUTH WINDS THIS EVENING WILL VEER
WESTERLY BY DAYBREAK FRIDAY AS THE FRONT APPROACHES THE BEACHES.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...WEAK COLD FRONT IN THE AREA AT THE START
OF THE PERIOD WILL LINGER ALONG THE COAST FRI THEN PUSH INLAND SAT
AS IT STARTS TO DISSIPATE. BRIEF PERIOD OF OFFSHORE FLOW FRI
MORNING WILL BE REPLACED BY LIGHT ONSHORE FLOW AS WEAK SEA BREEZE
DEVELOPS IN THE AFTERNOON. BY SAT BERMUDA HIGH WILL BE ON ITS WAY
TO REESTABLISHING ITSELF...RESULTING IN SOUTHWEST FLOW IN THE 10
TO 15 KT RANGE LATER SAT AND SAT NIGHT. SEAS 2 TO 3 FT FRI INTO
SAT BUILD TO 2 TO 4 FT LATER SAT AND SAT NIGHT.

LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 300 AM THURSDAY...BERMUDA HIGH WILL MAINTAIN 10 TO 15 KT
SOUTHWEST FLOW THROUGH THE PERIOD. NEARSHORE SEA BREEZE
DEVELOPMENT WILL ENHANCE ONSHORE FLOW EACH AFTERNOON. SEAS WILL
RUN 3 TO 4 FT.

&&

.TIDES/COASTAL FLOODING...
AS OF 300 AM THURSDAY...MINOR COASTAL FLOODING IS POSSIBLE DURING
THE NIGHTTIME HIGH TIDE OVER THE NEXT SEVERAL DAYS. THESE HIGHER
THAN NORMAL TIDES ARE THE RESULT OF THE PERIGEAN SPRING TIDE AND
FULL MOON WHICH OCCURS ON JULY 31. DEPARTURES OF PLUS 1/2 TO 1
FOOT MLLW WILL BE ENOUGH TO PRODUCE A BRIEF PERIOD OF MINOR
COASTAL FLOODING. THE RISK IS HIGHEST FOR PORTIONS OF THE LOWER
CAPE FEAR RIVER TO INCLUDE DOWNTOWN WILMINGTON. HOWEVER...THIS
CYCLE...EVEN THE BEACHES HAVE A SMALL RISK. HIGH TIDE TONIGHT IS
ABOUT 730 PM AT THE BEACHES AND ABOUT 10 PM IN DOWNTOWN
WILMINGTON. A COASTAL FLOOD ADVISORY WILL BE ISSUED BY THE
NATIONAL WEATHER SERVICE IF COASTAL FLOODING IS EXPECTED.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.

&&

$$

NEAR TERM...TRA
SHORT TERM...III
LONG TERM...III
AVIATION...DL
TIDES/COASTAL FLOODING...RJD



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