Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 261043
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
643 AM EDT SAT JUL 26 2014

.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER THE REGION BRINGING HOT AND HUMID
CONDITIONS OVER THE WEEKEND AND MONDAY. ANOTHER UNUSUALLY STRONG
COLD FRONT MAY BRING STRONG TO SEVERE THUNDERSTORMS LATE MONDAY.
COOLER AND DRIER WEATHER WILL RETURN ON TUESDAY AND LAST THROUGH
MUCH OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM SATURDAY...BEWARE THE NW FLOW!...A BATTLE CRY THATS
BEEN USED HERE WHEN FLOW ALOFT IS FROM THE NW AND VARIOUS MODEL
GUIDANCE IS SAYING VERY LITTLE CHANCE FOR CONVECTION. IN
FACT...VARIOUS MODEL MOS GUIDANCE KEEP POPS EVEN BELOW ISOLATED
CHANCE. WITH THAT SAID...ITS DIFFICULT TO BEGIN WITH TO INDICATE A
POP-LESS FORECAST FOR THIS TIME OF THE YEAR. THE SEA BREEZE...
PIEDMONT TROF...AND WHATS LEFT OF A STATIONARY FRONT...SHOULD ALL
PROVIDE ENOUGH FORCING TO ENABLE CONVECTION INITIATION THIS
AFTERNOON/EVENING. MODELS DO ILLUSTRATE MUCH NOISE IN THE
MID-LEVELS WITH REFERENCE TO THE MOVEMENT OF S/W TROFS OR VORTS
ACROSS THE FA THRU TONIGHT. THEY ALSO SHOW NVA AND SUBSIDENCE
PASSING OVERHEAD AT VARIOUS TIMES THROUGH TONIGHT. LOOKING AT
SOUNDING DATA...IE. HOURLY NAMBUFR SOUNDINGS...AN IDENTIFIABLE
WEAK TO MODEST TEMP INVERSION IS PROGGED TO OCCUR ALOFT...MAINLY
BETWEEN 700 AND 600 MB. THIS WOULD DEFINITELY PUT A DAMPER ON
CONVECTION INITIATION. WITH ALL OF THIS SAID...WILL STILL
INDICATE POPS...ALBEIT ISOLATED...ACROSS PORTIONS OF THE FA THIS
AFTERNOON AND EVENING.

AS FOR TEMPS...MODEL MOS GUIDANCE INDICATES AROUND 90 FOR
AFTN MAXES...INCLUDING THE BEACHES. GIVEN THE DOWNSLOPE
TRAJECTORY IN THE WIND FIELD ALOFT...WILL GO A DEGREE OR 3 HIGHER
THAN MODEL MOS GUIDANCE CONSENSUS. THIS MEANS WIDESPREAD 90 DEGREE
READINGS TODAY...EXCEPT THE IMMEDIATE BEACHES WHERE UPPER 80S TO
PREVAIL. WILL REMAIN BELOW HEAT ADVISORY CONCERNS TODAY...BUT FOR
THE NEXT 2 DAYS THIS WILL NOT BE THE CASE.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...START OF NEXT WEEK WILL BE QUITE WARM WITH
HIGHS ON BOTH SUN AND MON RUNNING WELL INTO THE 90S. MID LEVEL RIDGE
WILL EXTEND EAST FROM THE SOUTHWESTERN CONUS SUN. FORECAST SOUNDINGS
SHOW CAPPING AROUND 800 MB...A RESULT OF SUBSIDENCE ON THE PERIPHERY
OF THE 5H RIDGE. CAPPING ALONG WITH DEEP WESTERLY FLOW WILL MAKE
EVEN ISOLATED CONVECTION HARD TO COME BY. CANNOT RULE OUT AN
ISOLATED SHORT LIVED SHOWER ALONG OR JUST BEHIND THE SEA BREEZE BUT
NOTHING WORTH CARRYING A POP ABOVE 10%. 850 TEMPS IN THE 20C TO 22C
RANGE AND LACK OF MUCH CLOUD COVER/CONVECTION WILL PUSH HIGHS INTO
THE MID TO UPPER 90S AREA WIDE. DESPITE LIMITED CLOUD COVER SUN
NIGHT LOWS WILL BE KEPT IN THE UPPER 70S TO AROUND 80 BY
STRENGTHENING LOW LEVEL JET.

STRONG COLD FRONT WILL CROSS THE AREA ON MON WITH IMPRESSIVE 5H
TROUGH THE DRIVING FACTOR. BEST PRECIP CHANCES DURING THE PERIOD
WILL BE ON MON...AHEAD OF THE COLD FRONT WHEN PRECIPITABLE WATER
VALUES WILL BE AROUND 2 INCHES. MON IS ALSO SHAPING UP TO BE A HOT
DAY WITH 850 TEMPS ONCE AGAIN IN THE LOWER 20C RANGE. HIGHS IN THE
MID 90S COMBINED WITH DEWPOINTS IN THE LOW 70S WILL NOT ONLY PRODUCE
HEAT INDEX VALUES AT OR ABOVE 105F...LIKELY WARRANTING A HEAT
ADVISORY...BUT WILL SET THE STAGE FOR AFTERNOON CONVECTION. MID
LEVEL COOLING COMBINED WITH STRONG LOW LEVEL CONVERGENCE ALONG THE
FRONT AND VERY WARM LOW LEVELS IS LIKELY TO PRODUCE WIDESPREAD
SHOWERS AND THUNDERSTORMS. WHILE IT APPEARS THE CORE OF THE UPPER
LEVEL JET WILL REMAIN NORTH OF THE AREA STRONG TO SEVERE CONVECTION
REMAINS A POSSIBILITY BASED ON THERMODYNAMIC PROFILES MON
AFTERNOON/EVENING AND SPC HAS  PLACED MUCH OF THE FORECAST AREA
WITHIN A SLIGHT RISK AREA FOR DAY 3.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 3 AM SATURDAY...NOTICEABLE AIR MASS CHANGE FROM MON AFTERNOON
TO TUE AFTERNOON AS BOTH HEAT AND HUMIDITY WILL BE LACKING.
PRECIPITABLE WATER VALUES DROP DOWN TO AROUND AN INCH TUE WHILE
NORTHERLY FLOW USHERS COOLER AIR INTO THE REGION. TROUGH AXIS
REMAINS JUST WEST OF THE AREA FOR THE PERIOD WITH GENERALLY DEEP
WESTERLY FLOW KEEPING MID LEVELS DRY. GFS/ECMWF BOTH SHOW A
SHORTWAVE CROSSING THE AREA TUE NIGHT INTO WED BUT DIFFER ON ITS
STRENGTH AND IMPACT. WILL NOT BE ADDING ANY PRECIP CHANCES GIVEN THE
UNFAVORABLE ENVIRONMENT AND DIFFICULTY IN ACCURATELY DEPICTING SUCH
FEATURES IN THE EXTENDED PERIOD.

FORECAST SOUNDINGS DO NOT SHOW MUCH OF AN INCREASE IN DEEP MOISTURE
THROUGH THE PERIOD...PWATS BARELY EXCEED 1.25 INCHES DURING THE
PERIOD...SO DIURNAL CONVECTION WILL BE SCARCE. CANNOT RULE OUT SOME
ISOLATED STORMS ANY GIVEN AFTERNOON BUT DO NOT THINK A MENTIONABLE
POP IS WARRANTED. BEST CHANCES WOULD BE NEAR THE COAST...ALONG OR
JUST BEHIND THE SEA BREEZE BUT EVEN HERE COVERAGE ABOVE 20% IS
UNLIKELY. TEMPERATURES WILL REMAIN BELOW CLIMO THROUGH THE PERIOD
WITH POTENTIAL FOR SOME RADIATIONAL COOLING OVERNIGHT DURING THE
MIDDLE OF THE WEEK.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 06Z...FEW LEFTOVER CONVECTIVE DEBRIS CLOUDS OTHERWISE
RADIATIONAL COOLING WILL RULE THE AM HOURS. RESIDUAL LOW LEVEL
MOISTURE WILL RESULT IN LOW STRATUS CLOUD DECKS...MAINLY AFFECTING
THE INLAND TERMINALS. FOG WILL ALSO BECOME A HINDRANCE TO AVIATORS
WITH GUIDANCE POINTING TOWARDS DENSE FOG ESPECIALLY ACROSS THE
INLAND TERMS. BY 12Z AND AFTER A COUPLE HOURS OF INSOLATION...THE
FOG SHOULD QUICKLY DISSIPATE. FOR SATURDAY MIDDAY THROUGH EARLY
EVENING...2 SFC BASED FEATURES...SEA BREEZE AND THE PIEDMONT
TROF... WILL BE THE DRIVING FORCE FOR POSSIBLE ISOLATED
CONVECTION. HOWEVER...PROGGED SUBSIDENCE ALOFT WILL KEEP
THUNDERSTORM ACTIVITY LIMITED IN AREAL COVERAGE AND IN STRENGTH.

EXTENDED OUTLOOK...SHOWERS/TSTMS/TEMPO MVFR POSSIBLE SUNDAY AND
MONDAY. OTHERWISE EXPECT VFR.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM SATURDAY...THE OLD STALLED OUT FRONTAL BOUNDARY
ACROSS PORTIONS OF THE LOCAL WATERS TODAY WILL FINALLY DISSIPATE
AS IT BECOMES ABSORBED WITHIN THE SYNOPTIC FLOW. THE PIEDMONT TROF
ACROSS THE CENTRAL CAROLINAS IS PROGGED TO BECOME STRONGER THRU
TONIGHT. RIDGING FROM THE OFFSHORE ATLANTIC HIGH WILL EXTEND
WESTWARD JUST SOUTH OF THE AREA WATERS. THE SFC PRESSURE PATTERN
AND GRADIENT BETWEEN THESE 2 FEATURES WILL PRODUCE A TIGHTENING
GRADIENT THAT YIELDS ATLEAST 15 KT FOR SPEEDS LATER TODAY AND
TONIGHT. THE SFC PRESSURE PATTERN WILL TRANSITION INTO A SW FLOW
DIRECTION TODAY THRU TONIGHT.

SIGNIFICANT SEAS INITIALLY WILL BE DOMINATED BY A 2 FOOT ESE
GROUND SWELL. LATER THIS AFTERNOON AND TONIGHT...LOCALLY PRODUCED
WIND WAVES WILL INCREASE IN SIZE AND COVERAGE AND LIKELY BECOME
THE MORE DOMINATE OF THE 2. SEVEN SECOND DOMINATE PERIODS WILL
OCCUR.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...INCREASING SOUTHERLY FLOW AHEAD OF STRONG COLD
FRONT WILL LIKELY RESULT IN HEADLINES FOR ALL ZONES LATER SUN NIGHT
AND MON. NATURE OF THE HEADLINES IS AS OF YET UNDETERMINED. IT MAY
END UP THAT SCEC IS NEEDED SUN NIGHT AND THEN SCA MON AND PART OF
MON NIGHT. SOUTHWEST FLOW 15 TO 20 KT SUN WILL INCREASE TO A SOLID
20 KT SUN NIGHT AND MON. COMBINATION OF PROLONGED SOUTHWEST FLOW AND
INCREASE IN SPEEDS BUILDS SEAS FROM 3 TO 4 FT AT THE START OF THE
PERIOD TO 4 TO 6 FT ON MON. OFFSHORE FLOW DEVELOPS IN THE WAKE OF
THE FRONT LATER MON NIGHT WITH SPEEDS DROPPING TO 10 KT OR LESS BY
TUE MORNING. OFFSHORE COMPONENT AND DECREASE IN SPEEDS LATE MON
NIGHT WILL RESULT IN SEAS FALLING TO 3 TO 4 FT BY THE END OF THE
PERIOD.

LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3 AM SATURDAY...HIGH PRESSURE WILL BE SLOW TO BUILD IN BEHIND
THE DEPARTING COLD FRONT TUE INTO WED...LEAVING A WEAK AND ILL
DEFINED GRADIENT OVER THE WATERS DURING THE FIRST HALF OF THE
PERIOD. WINDS WILL BE VARIABLE WITH SPEEDS UNDER 10 KT TUE INTO WED.
INFLUENCE OF SURFACE HIGH OVER THE MIDWEST BECOMES MORE PRONOUNCED
ON WED WITH 10 TO 15 KT NORTHEAST FLOW DEVELOPING BY AFTERNOON. SEAS
WILL TREND DOWN TUE AND TUE NIGHT BEFORE INCREASING SLIGHTLY ON WED
INTO WED NIGHT AS WIND FIELD BECOMES MORE DEFINED.

&&

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

&&

$$
SYNOPSIS...III
NEAR TERM...DCH
SHORT TERM...III
LONG TERM...III
AVIATION...DCH



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