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[Printable]
591
FXUS62 KILM 300736
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
336 AM EDT WED JUL 30 2014

.SYNOPSIS...
DRY AND COOL WEATHER WILL CONTINUE THROUGH INTO LATE WEEK AS
CANADIAN HIGH PRESSURE SETTLES ACROSS THE AREA. A COASTAL FRONT
WILL LIFT BACK NORTH ACROSS THE AREA FRIDAY AND INTO THE
WEEKEND...BRINGING GOOD RAIN CHANCES INTO EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 330 AM WEDNESDAY...THE UNUSUAL AMPLIFIED UPPER LONGWAVE TROF
TO REMAIN SITUATED...AFFECTING MUCH OF THE U.S. EAST OF THE
MISSISSIPPI RIVER VALLEY. THE N-S ORIENTED UPPER TROF AXIS IS
PROGGED TO REMAIN JUST WEST OF THE FA. OVERALL...THE ILM CWA WILL
CONTINUE TO EXPERIENCE BELOW NORMAL TEMPS AND COMFORTABLE RHS. FOR
THIS TIME OF THE YEAR TO HAVE COMFORTABLE RHS IS DIFFICULT TO COME
BY...BUT TO HAVE POTENTIALLY UP TO 3 TO 4 DAYS IN A ROW...IS A GIFT.
WILL BASICALLY USE PERSISTENCE FOR THE NEAR TERM FORECAST.
CHANNELED WEAK VORTICITY TRAVELING WITHIN THE UPPER TROF...AS SEEN
WITH 7H AND 5H PROGS...WILL OCCASIONALLY PUSH ACROSS THE FA. THIS
FORCING AND ENOUGH MOISTURE EXISTING BELOW THE SUBSIDENCE LAYER WILL
RESULT IN CU/AC/SC CLOUDS AT ALMOST ANY TIME ACROSS THE FA. MAJORITY
OF IT WILL BE SCATTERED IN NATURE. THE FORCING FROM THE RESULTANT
WIND BOUNDARY WILL BE ENOUGH FOR A BROKEN DECK OF CLOUDS TO OCCUR.
WILL REMAIN ON THE FENCE AS FAR AS PLACING ISOLATED SHOWERS IN THE
FORECAST EXTENDING FROM THE RESULTANT WIND BOUNDARY TO THE COAST
WHERE ENOUGH JUICE IE. CAPE...HAVING BECOME AVAILABLE. FOR NOW POPS
WILL BE ADVERTISED JUST UNDER 15 PERCENT. TEMPS HAVE BEEN A HEADACHE
THE PAST SEVERAL DAYS...MAINLY THE MAX TEMPS. OVERALL..WILL GO ALONG
WITH PERSISTENCE...STAYING CLOSER TO THE GFS MOS GUIDANCE...WHICH
HAS BEEN PERFORMING WELL OF LATE.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM WEDNESDAY...COOL WEATHER WILL CONTINUE FOR THE SHORT
TERM THANKS TO A CLOSED LOW PRESSURE NEAR THE HUDSON BAY MAINTAINING
AN ANOMALOUSLY STRONG MID-LEVEL TROUGH ACROSS THE EAST. THIS FEATURE
WILL VERY GRADUALLY WEAKEN AND LIFT TO THE NORTHEAST BY THE
WKND...AND THUS SUBTLE THICKNESS INCREASES WILL OCCUR...BUT AT THE
SAME TIME THIS WILL ALLOW WINDS TO BACK MORE TO THE S/SW OFF THE
SURFACE...INCREASING COLUMN MOISTURE. PWATS THURSDAY AROUND 1.75
INCHES ARE RIGHT AROUND SEASONABLE VALUES FOR THE BEGINNING OF
AUGUST...AND SCATTERED SHOWERS/TSTMS WILL BE POSSIBLE THURSDAY.
FRIDAY IS EXPECTED TO BE THE WETTER DAY HOWEVER...AS COASTAL
TROUGH/WARM FRONT BEGIN TO LIFT BACK TOWARDS THE COAST...LIKELY
MOVING ONSHORE LATE FRIDAY. PWATS RISE TO AROUND 2 INCHES...WHICH
WILL COMBINE WITH SURFACE CONVERGENCE ALONG THE BOUNDARY...AND
CONTINUED UPPER DIFFLUENCE WITHIN THE JET-STREAK EMBEDDED DOWNWIND
OF THE LARGE SCALE TROUGH...TO CREATE A GOOD CHANCE FOR SHOWERS AND
STORMS. THERE WILL BE SOME DIURNAL ENHANCEMENT/NOCTURNAL DECREASE OF
THE CONVECTION FRIDAY...BUT DO EXPECT SHOWERS TO CONTINUE THROUGHOUT
FRIDAY NIGHT.

TEMPS WILL REMAIN BELOW NORMAL FOR THE DATE...WITH MID 80S EXPECTED
THURSDAY...ALTHOUGH A FEW SPOTS IN THE PEE DEE REGION OF SC MAY
APPROACH 90. ALTHOUGH THICKNESSES RISE FRIDAY...CLOUDS AND PRECIP
WILL LIMIT WARMING...AND THUS HIGHS WILL BE A DEGREE OR TWO COOLER
THAN THURSDAY. MINS BOTH NIGHTS WILL FALL INTO THE UPPER 60S
INLAND...AROUND 70 AT THE COAST.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 300 AM WEDNESDAY...A WET PERIOD EXPECTED THE FIRST HALF OF THE
LONG TERM...MAKING THE FIRST WEEKEND OF AUGUST COOL AND UNSETTLED.
LARGE UPPER TROUGH WHICH HAS BEEN PLAGUING THE EASTERN CONUS FOR
SOME TIME WILL FINALLY...SLOWLY...BEGIN TO ERODE THANKS TO THE
WEAKENING OF THE PARENT VORTEX...AND THE AMPLIFICATION OF THE RIDGE
ACROSS THE ATLANTIC OCEAN. WHILE THIS RIDGE WILL EVENTUALLY OVERCOME
THE PERSISTENT TROUGH ACROSS THE EAST...IT WILL LIKELY TAKE UNTIL
TUESDAY FOR ANY NOTICEABLE WARMING/DRYING TO OCCUR LOCALLY...AND
TEMPS WILL REMAIN BELOW NORMAL THROUGH THE PERIOD.

THE REASON FOR THIS IS BECAUSE AS THE TROUGH BEGINS RECEDE TO THE
WEST...A COASTAL TROUGH/WARM FRONT WILL STALL NEAR THE AREA DURING
THE WEEKEND. THIS PROVIDES STRONG LOW-LEVEL MOIST ADVECTION...WHILE
MID-LEVEL MOIST ADVECTION OCCURS ON INCREASING S/SW FLOW DOWNWIND OF
THE TROUGH AXIS. THIS PRODUCES PWATS OVER TWO INCHES...WHICH COMBINE
WITH SURFACE CONVERGENCE AND UPPER DIFFLUENCE WITHIN THE JET STREAK
AROUND THE BASE OF THE TROUGH TO CREATE SCATTERED TO WIDESPREAD
SHOWERS AND THUNDERSTORMS SATURDAY...SUNDAY...AND EVEN INTO MONDAY.
FINALLY BY TUESDAY THE SURFACE TROUGH WASHES OUT...RIDGING TAKES
HOLD ALOFT...AND MORE SEASONABLE WEATHER DEVELOPS FOR THE MIDDLE OF
NEXT WEEK.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
AS OF 06Z...LEFTOVER DEBRIS CLOUDS FROM EARLIER ROGUE SHRA
EARLIER WILL AFFECT MAINLY THE ILM TERMINAL WITH MID-LEVEL
CEILINGS...ELSEWHERE...MAINLY SKC. VFR CONDITIONS THROUGH THE
FORECAST ISSUANCE PERIOD...WITH BRIEF MVFR CONDITIONS FROM REDUCED
VSBY FROM BR ACROSS THE COASTAL TERMS. SFC PRESSURE PATTERN AND
RELAXED GRADIENT TO YIELD CALM TO NORTHEAST WINDS 5 KT OR LESS
OVERNIGHT. FOR WEDNESDAY...PLENTY OF MOISTURE BELOW 700MB...WITH
THE DAYS INSOLATION THE FA WILL OBSERVE SCT/BKN 5K TO 10K FOOT
CEILINGS. WINDS DURING DAYTIME WED WILL START OUT NORTHEAST
AROUND 5 KT...VEERING TO THE E AND SE ESPECIALLY ACROSS THE
COASTAL TERMS DUE TO THE RESULTANT WIND BOUNDARY DEVELOPING AND
PUSHING INLAND. ISOLATED CONVECTION REMAINS POSSIBLE ALONG THE
RESULTANT WIND BOUNDARY...BUT NOT ENOUGH TO PLACE IN THE TAFS AT
THIS TIME. THE LOWERED CEILINGS WILL BE A REFLECTION OF THIS
POSSIBILITY FOR NOW.

EXTENDED OUTLOOK...MVFR VSBYS DUE TO MORNING FOG FRIDAY AND
SATURDAY...OTHERWISE VFR. CHANCE MAINLY AFTN/EVNG SHRA/ISOLATED
TSRA THROUGH THE PERIOD.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 330 AM WEDNESDAY...SYNOPTICALLY THE AREA WATERS WILL LIE IN
BETWEEN A BROAD SFC LOW WELL OFFSHORE ALONG THE STATIONARY
FRONT...AND CENTER OF WEAK HIGH PRESSURE ACROSS THE CAROLINAS.
THE RESULTING SFC PRESSURE PATTERN AND GRADIENT ACROSS THE ILM
WATERS WILL PRODUCE NE-E WINDS AROUND 10 KT. THE EXCEPTION WILL BE
THE NEAR SHORE WATERS FOR THIS AFTN AND EVENG...WITH THE DEVELOPMENT
AND INLAND PROGRESSION OF THE RESULTANT WIND BOUNDARY...WINDS WILL
BECOME SE AT 10-15 KT. SIGNIFICANT SEAS WILL CONTINUE TO BE THE
COMBINED EFFORTS OF THE LOCALLY PRODUCED 1-2 FOOT WIND DRIVEN WAVES
AT 4 SECOND PERIODS...AND THE ESE 1-2 FOOT GROUND SWELL AT 8-9
SECOND PERIODS. IN ESSENCE...SIGNIFICANT SEAS WILL BE AROUND 3 FEET
THRUOUT THE FORECAST PERIOD.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM WEDNESDAY...STALLED COLD FRONT/COASTAL TROUGH WELL
OFFSHORE WILL BE PUSHED BACK TOWARDS THE COAST THURSDAY BEFORE
MOVING ONSHORE DURING FRIDAY. THE GRADIENT WILL REMAIN WEAK NEAR
THIS FEATURE...WITH WINDS AROUND 10 KTS THROUGH THE PERIOD...BUT A
VEERING FROM THE EAST THURSDAY...TO SE ON FRIDAY...WILL OCCUR BEHIND
THIS BOUNDARY. SEVERAL WAVE GROUPS WILL EXIST WITHIN THE
SPECTRUM...BUT A LOW AMPLITUDE SE GROUND SWELL AND EAST AND
SOUTHEAST WIND WAVES WILL COMBINE TO PRODUCE 2-3 FT SEAS THROUGH THE
PERIOD.

LONG TERM /SATURDAY THROUGH SUNDAY/...
AS OF 300 AM WEDNESDAY...COASTAL TROUGH/WARM FRONT WILL LIFT NW OF
THE WATERS BY EARLY SATURDAY...AND REMAIN INLAND DURING THE WKND.
WINDS BEHIND THIS FEATURE WILL VEER SLOWLY FROM SE TO SW...AT SPEEDS
OF 10-15 KTS. WAVE HEIGHTS WILL BE PREDOMINANTLY 2-3 FT THROUGH THE
EXTENDED...BUT SOME 4 FT SEAS ARE POSSIBLE SUNDAY THANKS TO THE
LONGER SPATIAL FETCH FROM THE S/SE.

&&

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

&&

$$
SYNOPSIS...JDW
NEAR TERM...DCH
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...DCH
MARINE...DCH/JDW









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