-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 180020
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
820 PM EDT FRI MAY 17 2013

.SYNOPSIS...
WARM TEMPERATURES WILL CONTINUE INTO EARLY NEXT WEEK AS BERMUDA
HIGH PRESSURE REMAINS ANCHORED OFFSHORE. WEAK LOW PRESSURE ALOFT
WILL BRING A FEW AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS
OVER THE WEEKEND INTO EARLY NEXT WEEK. DRIER WEATHER IS EXPECTED
THROUGH THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
-- Changed Discussion --
AS OF 730 PM FRIDAY...MODIFIED TEMPS/DEWPOINTS/WINDS ACROSS THE
ILM CWA DUE TO THE SEA BREEZE CIRCULATION AND ITS EXTENT INLAND.
THIS WAS DONE PRIMARILY FOR THE REMAINDER OF THIS EVENING...THEN
MESHING THESE CHANGED METEOROLOGICAL PARAMETERS WITH THE GOING
FORECAST AFTER MIDNIGHT. IN ADDITION..THE LATEST KLTX 88D
INDICATES NO ECHOES ACROSS THE FA...AND THEREFORE WILL REMOVE ALL
POPS THIS EVENING AND THE OVERNIGHT PERIOD. MODELS INDICATE A LACK
OF FORCING... DECREASING INSTABILITY...AND CONTINUED SUBSIDENCE
ALOFT...ALL POINTING NEGATIVE FOR ANY SHRA/TSRA ACROSS THE FA
OVERNIGHT. THE FA WILL REMAIN SOUTH OF THE BACKDOOR COLD FRONT...
WHICH IS PROGGED TO STALL IN THE VICINITY OF CAPE LOOKOUT. SOME
OF THE NORMALLY PRONE LOCATIONS MAY OBSERVE PATCHY GROUND FOG
OVERNIGHT...ESPECIALLY THOSE LOCATIONS WHERE WINDS COMPLETELY
DECOUPLE.

PREVIOUS DISCUSSION................................................
AS OF 330 PM FRIDAY...CONVECTIVE DEVELOPMENT HAS BEEN MEASURED AS
EXPECTED THIS AFTERNOON AS CUMULUS CLOUDS ARE JUST NOW BEGINNING
TO DEVELOP. THE LATEST GUIDANCE INCLUDING THE HIGH RESOLUTION RAP
AND GLOBAL GFS SHOW SOME ACTIVITY TO THE NORTH LATER THIS
AFTERNOON. I HAVE TWEAKED THE POPS TO REPRESENT THIS TREND OF
WHICH THE FORCING INCLUDES THE SEA BREEZE FRONT...POSSIBLY A
RESIDUAL OUTFLOW FROM ACTIVITY YESTERDAY AND A BACKDOOR FRONT. FOR
THE OVERNIGHT HOURS...I HAVE REMOVED POPS AFTER 0300 UTC. ENOUGH
DEBRIS CLOUDINESS SHOULD REMAIN TO PREVENT ANY SIGNIFICANT FOG
DEVELOPMENT. FOR THE OVERNIGHT LOWS...NUMERICAL GUIDANCE IS IN
EXCELLENT AGREEMENT WITH MIDDLE 60S ACROSS THE BOARD.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS OF 330 PM FRIDAY...DIURNAL CONVECTION SHOULD BECOME A BIT MORE
ACTIVE OVER THE WEEKEND AS WEAK LOW PRESSURE ALOFT BRINGS SEVERAL
DEGREES OF H5 COOLING AND MID-LEVEL MOISTURE INCREASES. SATURDAY
A WEAK E-W SURFACE BOUNDARY WILL LURK ACROSS OR JUST NORTH OF OUR
VERY NORTHERN TIER OF FORECAST ZONES. THIS FEATURE HOWEVER WILL
LIFT NORTH AND WEAKEN BY LATE SATURDAY. THE SEA BREEZE FRONT WILL
PLAY A ROLE IN AFTERNOON CONVECTION INLAND FROM THE COAST...AND
SUBSEQUENT OUTFLOW BOUNDARIES COULD SUSTAIN ACTIVITY SATURDAY AND
SUNDAY INTO THE EVENING HOURS. HIGHEST POP VALUES WILL BE FAVORED
DURING AND AFTER MAXIMUM DIURNAL HEATING...AND MOSTLY INLAND SINCE
THE RIDGE OFFSHORE WILL KEEP HIGHEST PWATS OVER THE INTERIOR.
TEMPERATURES OVER THE WEEKEND WILL BE VERY NEAR TO SEVERAL DEGREES
ABOVE CLIMATE STANDARDS FOR MIDDLE MAY.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 330 PM FRIDAY...TEMPS FAIRLY CLOSE TO CLIMO ON MONDAY DESPITE
BERMUDA HIGH AND UPPER RIDGE OTHERWISE SUPPORTIVE OF WARMER TEMPS.
MID LEVEL SHORTWAVE MAY LEAD TO MORE WIDESPREAD CONVECTION THAN
NORMALLY EXPECTED IN SUCH A SETUP AND THERE MAY BE SOME LEFTOVER
CONVECTIVE DEBRIS CLOUDINESS TO HINDER INSOLATION. THE WEAK SHORT
WAVE MAY MOVE OFF THE COAST (ALTHOUGH NOT ACCORD TO GFS) LEADING TO
A DECREASE IN CONVECTIVE COVERAGE AND FAVORING THE TREND TOWARDS
WARMTH THROUGH WEDNESDAY AT LEAST. LATTER HALF OF THE PERIOD SEES
THE MID LVL RIDGE BEING SUPPRESSED FROM THE N BY TROUGHINESS
DEVELOPING OVER ERN CANADA. NOT SURE HOW MUCH SUCCESS IT`LL HAVE
THOUGH ESPECIALLY IN MAKING IT THIS FAR SOUTH AT LEAST WITH THE
RAPIDITY SHOWN BY THE GFS. EC AND CANADIAN ARE SLOWER SHOWING THAT
COLD FRONT ASSOC WITH THE TROUGH NOT CLOSE ENOUGH UNTIL FRIDAY TO
START RAMPING UP POPS AND TEMPERING THE WARMTH.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 00Z...CURRENTLY VFR AT ALL TERMS THIS EVENING WITH S-SW WINDS
AOB 10 KTS. MID TO HIGH CLOUDS WILL LINGER TONIGHT AS AN UPPER
DISTURBANCE APPROACHES FROM THE WEST. THESE CLOUDS ALONG WITH
ENHANCED NEAR SFC WINDS SUGGEST WIDESPREAD FOG IS UNLIKELY...BUT
PATCHY FOG IS CERTAINLY POSSIBLE BEFORE 12Z. HAVE INCLUDED MVFR
VSBYS INLAND...KLBT/KFLO...ALONG WITH FOG-PRONE KCRE. EXPECT
INCREASING LOW/MID-LEVEL CLOUDS ON SATURDAY WITH S-SW WINDS 8-12
KTS. ISOLATED SHOWERS/TSTMS ARE POSSIBLE IN THE AFTN HOURS...BUT
CHANCES ARE TOO LOW TO MENTION IN TAFS ATTM.

EXTENDED OUTLOOK...AFTN SHOWERS/TSTMS POSSIBLE THROUGH MONDAY.
OTHERWISE VFR.

&&

.MARINE...
-- Changed Discussion --
NEAR TERM /THROUGH TONIGHT/...
AS OF 745 PM FRIDAY...MODELS PROG THE BACK DOOR COLD FRONT TO
STALL IN THE VICINITY OF CAPE LOOKOUT OVERNIGHT BEFORE LIFTING
BACK TO THE NORTH SATURDAY INTO SUNDAY. THE SEA BREEZE CIRCULATION
OVER THE NEAR SHORE WATERS WILL DECAY QUICKLY AFTER SUNSET. THIS
LEAVES RIDGING FROM THE WESTERN ATLANTIC HIGH TO RESUME PRIMARY
CONTROL OF THE WINDS OVERNIGHT. THE SFC PRESSURE PATTERN AND
GRADIENT TO YIELD SSW 10-15 KT WINDS TO VEER TO SW AROUND 10 KT
DURING THE HOURS AFTER MIDNIGHT. SIGNIFICANT SEAS WILL RUN 2 TO
OCCASIONALLY 3 FT. SIG. SEAS WILL BE A COMBINATION OF A 1.0 TO
1.5 FOOT SE GROUNDSWELL AT 8 SECOND PERIODS...AND LOCALLY PRODUCED
4 TO 5 SECOND PERIOD WIND DRIVEN WAVES.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 330 PM FRIDAY...SUMMER-LIKE BERMUDA HIGH PRESSURE REGIME WILL
REMAIN IN PLACE OVER THE WATERS...BRINGING MODERATE SW WINDS OVER
THE WEEKEND. THE WINDS WILL BE A BIT STRONGER SUNDAY AS HIGH
PRESSURE OFFSHORE STRENGTHENS...AND INTERACTS WITH LOWER PRESSURE
INLAND. SEAS OF 2-4 FEET SATURDAY MAY INCREASE TO 3-5 FEET BY
SUNDAY AFTERNOON AS WINDS INCREASE TO 15-20 KT AND PERSIST INTO
EARLY MONDAY. SEAS WILL BE A MIX OF MODERATE SSW WIND-WAVES AND
SE WAVES 1-2 FEET EVERY 8-10 SECONDS.

LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 330 PM FRIDAY...LITTLE MEANINGFUL VARIABILITY FROM DAY TO DAY
FOR THE EXTENDED. SOUTHWESTERLY WINDS BORNE OF BERMUDA HIGH PRESSURE
EXPECTED FOR THE DURATION WITH SPEEDS TENDING TO REMAIN IN THE 10 TO
15KT RANGE. THERE IS A POSSIBILITY THAT LATER IN THE PERIOD THE HIGH
BECOMES SUPPRESSED AND DEFORMED BY THE APPROACH OF A COLD FRONT FROM
THE NORTH. THIS WOULD LEAD TO A DROP IN WIND SPEEDS. CURRENT
THINKING THOUGH IS THAT THIS BOUNDARY WILL BE QUITE A BIT SLOWER
THAN DEPICTED IN MODEL GUIDANCE AND SO THIS WILL NOT CURRENTLY BE
INCORPORATED INTO THE FORECAST.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...MJC
NEAR TERM...DCH/SHK
SHORT TERM...MJC
LONG TERM...MBB
AVIATION...BJR