000
FXUS62 KILM 171931
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
331 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/...
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.

&&

.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 TROUGINESS
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 /19Z FRIDAY THROUGH WEDNESDAY/...
AS OF 19Z...EXPECT VFR THROUGH THE VALID PERIOD...WITH THE EXCEPTION
OF POSSIBLE AREAS OF FOG SATURDAY MORNING.

FOR THE REST OF THE DAY EXPECT SCT/BKN MID TO HIGH LEVEL CLOUDS WITH
SOUTHWEST WINDS AOB 10 KTS...BECOMING MORE SOUTH ALONG THE COAST
WITH THE AFTERNOON SEABREEZE. WOULD NOT COMPLETELY RULE OUT AN
ISOLATED SHOWER THIS AFTERNOON...BUT CONFIDENCE IS LOW. INTO THE
OVERNIGHT HOURS...CLOUD COVERAGE WILL CONTINUE...AND LIKELY
INCREASE...WITH WINDS BECOMING LIGHT. TOWARDS THE EARLY MORNING
HOURS ON SATURDAY...CANNOT RULE OUT PATCHY FOG...ESPECIALLY INLAND.
TIME-HEIGHT ANALYSIS AND FCST SOUNDINGS SUGGEST POSSIBILITY OF
FEW/SCT LOW CLOUDS IN THE MORNING AS WELL. AFTER DAYBREAK...CLOUDS
WILL GRADUALLY BEGIN TO SCATTER OUT WITH SOUTHWEST WINDS AOB 8 KTS.

EXTENDED OUTLOOK...CHANCE OF AFTN SHOWERS/TSTMS SATURDAY THROUGH
MONDAY...OTHERWISE VFR.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 330 PM FRIDAY...PERSISTENCE WILL BE THE THEME FOR THE COASTAL
WATERS THROUGH TONIGHT AS A SOUTHWEST FLOW OF 10-15 KT PREVAILS.
WAVEWATCH SEAS WILL CONTINUE IN A 2-4 FOOT RANGE. THE BACKDOOR
FRONT SHOULD STAY WELL TO THE NORTH PRECLUDING ANY WIND SHIFT.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 330 PM FRIDAY...SUMMERLIKE 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.

&&

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

&&

$$


NEAR TERM...SHK
SHORT TERM...MJC
LONG TERM...MBB
AVIATION...SGL/SHK