Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 210252
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1052 PM EDT MON APR 20 2015

.SYNOPSIS...
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS THIS
EVENING...WILL BECOME ISOLATED OVERNIGHT PRIOR TO THE COLD FRONTAL
PASSAGE EARLY TUESDAY. DRY AND SEASONABLE HIGH PRESSURE WILL
BUILD ACROSS THE AREA TUESDAY AND WEDNESDAY...FOLLOWED BY THE NEXT
COLD FRONTAL PASSAGE ON THURSDAY. THIS FRONT WILL STALL JUST SOUTH
OF THE AREA FRI AND INTO THE UPCOMING WEEKEND. LOW PRESSURE MAY
DEVELOP ALONG THE STALLED FRONT AND AFFECT THE FORECAST AREA LATE
FRI AND INTO THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
AS OF 1015 PM MONDAY...THICK CANOPY OF MID TO UPPER LEVEL MOISTURE
HAD LIMITED INSOLATION FROM REACHING THE SFC THIS AFTN AND EARLY
EVENING. THIS HAS RESULTED WITH LESS SFC BASED INSTABILITY AVBL
FOR POSSIBLE CONVECTION AHEAD OF THE APPROACHING SFC COLD FRONT.
LOOKING AT THE CURRENT 88D RADAR MOSAIC ACROSS THE LOCAL FA AND
UPSTREAM...SHOWER AND THUNDERSTORM ACTIVITY HAS DWINDLED TO NEARLY
NOTHING. WITH THE ILM CWA WITHIN THE RIGHT REAR QUADRANT OF AN
UPPER LEVEL JET INTO THE PRE-DAWN TUE HRS...AND THE SFC COLD
FRONT PUSHING ACROSS THE FA PRIOR TO DAWN...WILL BOTH PROVIDE THE
DYNAMICS FOR CONVECTIVE DEVELOPMENT. HOWEVER...SFC INSTABILITY
REMAINS LACKING ESPECIALLY WITH THE LOSS OF THE DAYS HEATING.
WITH ALL THIS SAID...HAVE ONCE AGAIN RE-ALIGNED THE REMAINDER OF
THE EVENING AND OVERNIGHT POPS AND SKY CONDITIONS. OVERALL...WILL
KEEP ISOLATED POPS ACROSS THE FA....MAINLY ALONG AND AHEAD OF THE
CFP. HAVE TWEAKED MIN TEMPS A DEGREE OR 2 LOWER...WHICH WILL
OCCUR AROUND OR JUST AFTER DAYBREAK TUE BASED ON HOW MUCH CAA
OCCURS AFTER THE CFP DURING THE EARLY AM TUE HRS.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 315 PM MONDAY...SPLIT FLOW PATTERN WILL PREVAIL AT THE MID
LEVELS THROUGH THE PERIOD WITH A GENERAL CYCLONIC PATTERN ACROSS
THE GREAT LAKES AND WESTERLY FLOW ACROSS THE SOUTHERN THIRD OF THE
U.S. THE GREAT LAKES TROUGH STRENGTHENS LATE IN THE PERIOD AND
DROPS SOUTH WITH A COLD FRONT MOVING ACROSS THE AREA BY EARLY
THURSDAY MORNING. I DID MAINTAIN THE SLIGHT CHANCE POPS WITH THIS
FEATURE AS MOST OF THE GUIDANCE IS INDICATING THIS. FOR TUESDAY
AND WEDNESDAY...NICE WEATHER PREVAILS UNDER WEAK HIGH PRESSURE.
THE ONLY ADJUSTMENT TO THE TEMPERATURE FORECAST WAS TO INCREASE
EXPECTED HIGHS FOR WEDNESDAY BASED ON THE LATEST GUIDANCE.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 315 PM MONDAY...SUFFICIENT MOISTURE MAY LINGER OVER MAINLY
SOUTHERN ZONES AS A COLD FRONT IS SLOW TO EXIT THE AREA. MOISTURE
WILL ALSO BE LIMITED BY MID LEVEL WESTERLY FLOW.  SOME LOWER
DEWPOINTS ADVECT IN BEHIND THIS BOUNDARY ON FRIDAY WITH A WEAK HIGH
TO OUR NORTH. CLOUDS INCREASE FRIDAY NIGHT AS THIS HIGH BEGINS TO
GET OVERRUN BY SOME WARM AND MOIST ADVECTION. RAIN SHOULD OVERSPREAD
THE REGION SOON THEREAFTER AS A FLAT WAVE OF LOW PRESSURE MOVES WEST
TO EAST ACROSS THE FRONT STALLED TO OUR SOUTH. WITH THE EXIT OF THIS
FEATURE SOME DRIER AIR ONCE AGAIN MANAGES TO PUSH IN FROM POINTS
NORTH BRINGING BACK A DRY FORECAST IN ADDITION TO TEMPERATURES A
SOLID CATEGORY BELOW CLIMO BY BOTH DAY AND NIGHT.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
AS OF 00Z...VFR CONDITIONS CURRENTLY PREVAIL AT THE TERMINALS AND
WILL THESE CONDITIONS WILL PERSIST THROUGH TONIGHT. A LARGE VEIL
OF CIRRUS IS SITUATED OVER THE COASTAL CAROLINAS WITH SOME MID
CLOUDS AND VIRGA MOVING NORTHEAST ACROSS THE AREA EARLY THIS
EVENING. CAN/T ENTIRELY RULE OUT A BRIEF -SHRA AT THE COASTAL
TERMINALS THRU 02-03Z TIME FRAME. MEANWHILE...AT KFLO AND KLBT THE
CHANCES FOR CONVECTION ARE DWINDLING WITH THE LOSS OF HEATING AND
EVER-SO-SLOW EASTWARD PROGRESSION OF SHRA/TSRA TO THE WEST OF THE
THESE TERMINALS. SURFACE WINDS WILL GRADUALLY VEER TO A WEST AND
NORTHWEST DIRECTION EARLY TOMORROW MORNING AS A WEAK FRONT MOVES
THROUGH.

EXTENDED OUTLOOK...EXPECT VFR WITH POSSIBLE SHOWERS THURSDAY AND
SATURDAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 PM MONDAY...SOLID SCEC FOR ALL WATERS. BORDERLINE SCA
MAINLY FOR SEAS ACROSS THE WATERS SOUTH OF CAPE FEAR TO LITTLE
RIVER INLET.

SFC PRESSURE PATTERN AND TIGHTENED GRADIENT AHEAD OF THE
APPROACHING SFC COLD FRONT LATE THIS EVENING AND OVERNIGHT...
WILL PRODUCE SW WINDS AT 15 TO 20 KT...BECOMING SW-W AT 15 TO 20
KT WITH GUSTS UP TO 25 KT DURING THE PRE-DAWN TUE HOURS. THE HIER
RANGE OF SPEEDS TO ESPECIALLY OCCUR ACROSS THE OUTER WATERS AWAY
FROM THE FRICTIONAL AFFECTS OF THE IMMEDIATE COAST. SIGNIFICANT
SEAS WILL BASICALLY RUN 3 TO 5 FT...EXCEPT 4 TO 5 FT WITH A FEW
POSSIBLE 6 FOOTERS ACROSS THE OUTER WATERS SOUTH OF CAPE FEAR TO
LITTLE RIVER INLET. WITH A MORE WESTERLY COMPONENT TO THE WINDS
LATER TONIGHT...THE BETTER FETCH TO PRODUCE THE HIER SEAS...IN
THIS CASE THE 6 FOOTERS...MAY BE REALIZED. WIND DRIVEN WAVES WILL
BE THE PRIMARY CONTRIBUTOR TO THE SIGNIFICANT SEAS...RESULTING IN
DOMINANT PERIODS OF 5 TO 6 SECONDS.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 315 PM MONDAY...RELATIVELY WEAK HIGH PRESSURE WILL REMAIN
ACROSS THE SOUTHEAST WITH A WESTERLY FLOW EMANATING FROM A DEEP
CYCLONE WELL TO THE NORTH ACROSS THE CAROLINAS. THIS WILL MAINTAIN A
LIGHT WESTERLY FLOW OF TEN KNOTS OR LESS ACROSS THE WATERS THROUGH
MIDDAY WEDNESDAY. THE FLOW THEN BACKS TO THE SOUTHWEST AS A FRONT
APPROACHES FROM THE NORTH. SPEEDS INCREASE AS WELL TO 10-15 KNOTS.
INITIAL SEAS OF 2-4 FEET WILL DIMINISH TO AROUND TWO FEET EARLY
WEDNESDAY BEFORE TRENDING UP AGAIN LATE.

LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 315 PM MONDAY...LIGHT WESTERLY FLOW ON THURSDAY AS A COLD FRONT
ONLY VERY SLOWLY SAGS TO OUR SOUTH. WITH MORE SOUTHWARD PROGRESS OF
THIS BOUNDARY THURSDAY NIGHT A NORTHERLY COMPONENT SHOULD BE ABLE TO
MATERIALIZE. NORTH WINDS WILL THEN LIKELY LAST INTO FRIDAY. THE
FRONT SHOULD RETURN CLOSER TO THE AREA ON SATURDAY AS A FLAT WAVE OF
LOW PRESSURE TRAVERSES ITS LENGTH WEST TO EAST. WINDS SHALL REMAIN
QUITE LIGHT BUT THERE MAY BE CONSIDERABLE VARIABILITY OF WIND
DIRECTION BOTH THROUGH THE DAY AS WELL AS FROM NORTH TO SOUTH. THAT
IS EASTERLY WINDS OVER NORTHERN WATERS WHILE SOUTHERN ZONES MAY VEER
MORE TO SOUTHEASTERLY OR EVEN SOUTHERLY.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...COASTAL FLOOD ADVISORY UNTIL 1 AM EDT TUESDAY FOR NCZ107.
MARINE...NONE.

&&

$$
SYNOPSIS...SHK
NEAR TERM...DCH
SHORT TERM...SHK
LONG TERM...MBB
AVIATION...SRP



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