Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 181916
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
316 PM EDT SAT APR 18 2015

.SYNOPSIS...
AN APPROACHING FRONTAL SYSTEM WILL BRING SHOWERS AND A CHANCE OF
THUNDERSTORMS SUNDAY AFTERNOON THROUGH MONDAY. A FEW STORMS COULD
BE STRONG TO SEVERE MONDAY. DRY AND SEASONABLE HIGH PRESSURE WILL
BUILD INTO THE AREA TUESDAY AND WEDNESDAY. A WEAK COLD FRONT MAY
BRING SHOWERS AND ISOLATED THUNDERSTORMS INTO LATE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 3 PM SATURDAY...A SUBTLE RIDGE WILL DEVELOP ACROSS THE AREA
TONIGHT AHEAD OF A POTENT SHORTWAVE THAT IS FINALLY MAKING ITS
MOVE TO THE WEST. THIS WILL ALLOW A FRONT NOW LOCATED ACROSS THE
OHIO VALLEY TO MAKE A RUN FOR THE AREA LATE TONIGHT. THIS WILL
SERVE...ALONG WITH A WEAK SHORTWAVE ALOFT...TO KEEP POPS IN THE
FORECAST BASICALLY THE ENTIRE TIME. ON TOP OF THIS THE NAM AND GFS
SHOW INDICATIONS OF ATLANTIC STREAMERS THAT TYPICALLY PRECEDE A
STRONGLY FORCED EVENT...LIKE ONE WE WILL BE SEEING LATER SUNDAY
AND MONDAY...MOVING ONSHORE LATE. I DO HAVE A POP MINIMUM AROUND
ZERO UTC...WITH A SLOW INCREASING TREND THEREAFTER. WENT ABOVE
GUIDANCE FOR OVERNIGHT LOWS AS DIURNAL RANGES CONTINUE TO BE
LIMITED BY THE ABUNDANT MOISTURE.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...PRIMARY HEADLINES INCLUDE POTENTIAL FOR A
GOOD SOAKING OF RAIN...AND A FEW STRONG THUNDERSTORMS. MONDAY
APPEARS THE MORE OPTIMUM SET-UP FOR STRONG/SEVERE STORMS WITH MORE
ROBUST KINEMATIC FIELDS AND STRONGER LOW-LEVEL HEATING JUST AHEAD
OF A COLD FRONT. EXTENSIVE CLOUD CANOPY SUNDAY MAY IMPEDE
CONVECTION INITIATION/GROWTH. SUNDAY MEANWHILE OFFERS THE HIGHER
RAIN AMOUNTS AS COLUMN MOISTURE SURGES AS A WARM FRONT LIFTS N OF
THE AREA AND PRECIPITABLE WATERS SURGE TO 1.8". SEVERAL MCV
PERTURBATIONS ALOFT SWEPT NE IN WAKE OF THE WARM FRONT MAY SUSTAIN
SHOWER AND STORM CHANCES INTO SUNDAY NIGHT. CURRENT IR ANIMATIONS
SHOW COLD TOPS INDEED FLARING ALONG THE NORTHERN GULF OF MEXICO.
WPC QPF DEPICTIONS SHOW .75-1 INCH BASIN AVERAGES SUNDAY...AND
WITH CONVECTIVE ELEMENTS...SOME AREAS LIKELY TO RECEIVE GREATER
AMOUNTS. MONDAY LESS BASIN QPF BUT MORE POWERFUL STORMS IN THE
CARDS WITH MAXIMUMS RISING WELL INTO THE 80S AND PARTIAL SUNSHINE
AIDING INSOLATION AND CELL POPS. SPC PAINTS SLIGHT RISK FOR BOTH
LATE SUNDAY AND MONDAY. BALMY PERIOD OVERALL AND BEST GUESS ON
FRONTAL PASSAGE NOW SLATED AROUND OR AFTER DAYBREAK TUESDAY.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 3 PM SATURDAY...AN ALMOST WINTERLIKE LOOKING UPPER PATTERN
FOR MOST OF THE PERIOD WITH A LARGE VORTEX IN THE VICINITY OF THE
GREAT LAKES. WESTERLY FLOW AROUND THIS FEATURE WILL KEEP MUCH OF THE
COLUMN DRY AND LEAD TO RAIN-FREE CONDITIONS LOCALLY. LOW LEVELS WILL
BE DRY AS WELL THROUGH SOME TIME WEDNESDAY AS HIGH PRESSURE BUILDS
IN FROM THE NORTHWEST. SOON THEREAFTER THIS HIGH MOVES OFFSHORE AND
SOME MOISTENING RETURN FLOW ENSUES. SOME GUIDANCE SHOWING THIS
CALLING FOR RAIN AS SOON AS THURSDAY BUT GIVEN THE AFOREMENTIONED
DOWNSLOPE FLOW STILL FEEL THAT THURSDAY NIGHT INTO FRIDAY IS THE
BETTER DAY TO INTRODUCE SOME RAIN CHANCES ESPECIALLY GIVEN THE
APPROACH OF A COLD FRONT. THOUGH THIS SURFACE BOUNDARY MAY LIE TO
OUR SOUTH ON SATURDAY SOME LOW LEVEL BAROCLINICITY PAIRED WITH MID
LEVEL VORT APPROACHING TO KEEP RAIN IN THE FORECAST.


&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
AS OF 18Z...TRICKY 24 HOUR FORECAST AS ONE SYSTEM IS EXITING AND
ANOTHER WILL ENTER THE PICTURE ON SUNDAY. LOOK FOR DIMINISHING
RAIN ACTIVITY THIS AFTERNOON WITH STILL SOME ISOLATED STUFF
THROUGH 21Z. CEILINGS WILL BE PREDOMINATELY MVFR...BUT WILL BOUNCE
AROUND QUITE A BIT. TONIGHT...NO RAIN IS EXPECTED UNTIL MORNING AS
THE NEXT SYSTEM APPROACHES. THIS ONE IS RATHER LARGE WITH HIGH
PRECIPITABLE WATER FOR THIS TIME OF YEAR. BY DAYBREAK SHOWERS WILL
BECOME NUMEROUS...SPREADING NORTHWARD WITH SOUTHEAST FLOW AT THE
SURFACE. VISIBILITIES COULD BRIEFLY COME DOWN TO A MILE IN THE
HEAVIER ACTIVITY.

EXTENDED OUTLOOK...SHOWERS ACCOMPANIED WITH ISOLATED THUNDER TO
AFFECT THE FORECAST AREA LATE SUNDAY THROUGH MONDAY
MORNING...RESULTING IN OCCASIONAL MVFR AND IFR CONDITIONS. SCATTERED
PCPN ASSOCIATED WITH A CFP MONDAY NIGHT FOLLOWED BY MAINLY VFR
CONDITIONS TUE. POSSIBLE SHOWERS RETURNING LATE WED INTO THU.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 PM SATURDAY...BENIGN CONDITIONS WILL CONTINUE ACROSS THE
COASTAL WATERS THIS AFTERNOON AND THROUGH THE OVERNIGHT HOURS. A
VERY WEAK PRESSURE PATTERN WILL SHAPE UP SLOWLY THIS EVENING AS A
BROAD SOUTHERLY FLOW AHEAD OF A POWERFUL SYSTEM TO THE WEST
DEVELOPS AND NORTHEAST WINDS MOVE IN BRIEFLY VERY LATE AS A BACK
DOOR FRONT MAKES A QUICK RUN TO THE SOUTH. OVERALL WILL MAINTAIN
AN EASTERLY WIND DIRECTION FOR THE SOUTHERN WATERS AND THE SAME
FOR THE NORTH CAROLINA WATERS TURNING NORTHEAST LATE TONIGHT. WIND
SPEEDS WILL BE MOSTLY AROUND TEN KNOTS WITH A SLIGHTLY HIGHER
RANGE...10 TO 15 KNOTS DEVELOPING NORTHERN LATE. ZONES SEAS WILL
REMAIN IN A 2-4 FOOT RANGE.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...EXERCISE CAUTION OR ADVISORY MARINE REGIME
ON TAP THIS PERIOD AS A FRONTAL SYSTEM APPROACHES AND WORSENS
LOCAL MARINE CONDITIONS. WAVE GROWTH HOWEVER MAY BE LIMITED SINCE
SE-S WIND FLOW HAS LIMITED STAYING TIME BEFORE WINDS GO SW EARLY
ON MONDAY. HAVE CAPPED SEAS AT 5 FEET SUNDAY FOR NOW WITH GUSTS TO
20 KT AHEAD OF THE COLD FRONT...SET TO CROSS THE WATERS TUESDAY
MORNING. SEVERAL STRONG TSTMS ARE POSSIBLE SUNDAY THROUGH THROUGH
EARLY TUESDAY AND SPECIAL MARINE WARNINGS MAY BE NEEDED AT TIMES.

LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 3 PM SATURDAY...OFFSHORE/NORTHWESTERLY POST COLD FRONTAL
FLOW REGIME ON TUESDAY WILL GROW LIGHTER LATE IN THE DAY AND AT
NIGHT AS CENTER OF HIGH PRESSURE APPROACHES. THE CENTER OF HIGH
PRESSURE MOVES OFFSHORE BY WEDNESDAY EVENING. THIS WILL BRING A
PERIOD OF VERY LIGHT GRADIENT WHEREIN WINDS REMAIN UNDER 10 KNOTS
AND VEER IN DIRECTION FOR AN EXTENDED TIME UNTIL FINALLY SETTLING
ON SOUTHERLY BY WED EVE. SUCH LIGHT WINDS IN THE ABSENCE OF SWELL
ENERGY OUGHT TO BE GOOD FOR MINIMAL SEAS OF 2 FT OR LESS. THE HIGH
MOVES FURTHER OFFSHORE ON THURSDAY ALLOWING FOR A ONE CATEGORY
RISE IN WINDS AND A WAVES FORECAST RISING TO JUST THE 2 TO 3 FT
RANGE.

&&

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

&&

$$

SYNOPSIS...MJC
NEAR TERM...SHK
SHORT TERM...MJC
LONG TERM...MBB
AVIATION...SHK


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