Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 010232
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
932 PM EST SAT JAN 31 2015

.SYNOPSIS...
SEASONABLE TEMPERATURES WILL ARRIVE SUNDAY ALONG WITH A GRADUAL
INCREASE IN MOISTURE. RAINFALL WILL SPREAD ACROSS THE REGION SUNDAY
NIGHT INTO MONDAY AHEAD OF A COLD FRONT. UNSETTLED WEATHER IS
EXPECTED AGAIN LATE IN THE WEEK WITH LOW PRESSURE POSSIBLY FORMING
OFF THE COAST ALONG A COLD FRONT THAT MOVES THROUGH ON THURSDAY.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
AS OF 930 PM SATURDAY...LIGHT BUT PERSISTENT SOUTH TO SOUTHWEST
WINDS ARE KEEPING TEMPERATURES IN THE MID 40S ALONG THE BEACHES.
ACCORDING TO MESONET DATA YOU DON`T HAVE TO GO MORE THAN ABOUT 0.5
TO 1 MILE INLAND FOR THE STRONG NOCTURNAL INVERSION TO DEVELOP WITH
TEMPERATURES DIVING INTO THE 30S. MID-LEVEL CLOUDINESS SHOULD
GRADUALLY INCREASE AFTER MIDNIGHT...TEMPERING THE IMPACT RADIATIONAL
COOLING WILL HAVE. ONLY SMALL TWEAKS HAVE BEEN MADE TO FORECAST
TEMPS AND DEWPOINTS WITH THIS 930 PM UPDATE. PREVIOUS DISCUSSION
FROM 630 PM FOLLOWS...

TYPICALLY ONE OF THE EASIEST TIMES TO BEAT THE MODELS IS THE FIRST
EVENING HIGH PRESSURE MOVES OFF THE COAST. THE MODELS TYPICALLY
UNDERESTIMATE THE INTENSITY OF RADIATIONAL COOLING AFTER SUNSET WITH
THE REMNANT COLD AIRMASS STILL CLINGING TO THE COASTAL PLAIN. IN
THIS CASE HOWEVER...CLOUDS ARE INCREASING RATHER QUICKLY FROM THE
WEST AND I AM HESITANT TO EVEN FORECAST LOWS QUITE AS COLD AS THE
GFS MOS WHICH HAS MID 20S ACROSS MOST OF THE AREA. I HAVE LOWERED
OUR FORECAST LOWS BY A COUPLE DEGREES... ESPECIALLY FOR THE COASTAL
COUNTIES JUST INLAND FROM THE BEACHES AS THE PREVIOUS FORECAST WAS
ONLY 5-8 DEGREES COLDER THAN 630 PM READINGS. THE REMNANT SEABREEZE
CIRCULATION FROM THIS AFTERNOON IS STILL BLOWING AT THE BEACHES BUT
SHOULD DIE AWAY IN THE NEXT HOUR WITH LIGHT/VARIABLE WINDS EXPECTED
OVERNIGHT. PREVIOUS DISCUSSION FROM 300 PM FOLLOWS...

FAIR AND COOL EVENING WEATHER IN STORE FOR NE SC AND SE NC AS THE
HEART OF A MODIFIED ARCTIC AIR MASS SETTLES OVER THE AREA THEN SLIPS
OFFSHORE INTO EARLY SUNDAY. INFILTRATION OF CIRRUS LATE TONIGHT AND
WEAK RETURN WIND FLOW WILL LIKELY SERVE TO LEVEL OFF OR
SIGNIFICANTLY DECELERATE TEMPERATURE FALLS INTO THE PRE-DAWN HOURS.
MAINLY CLEAR SKIES THIS EVENING AND LIGHT WIND ON THE OTHER HAND
WILL PROMPT RAPID DROPS IN TEMPERATURES...WITH SUB-FREEZING READINGS
LIKELY BEFORE MIDNIGHT IN MANY LOCATIONS AWAY FROM BEACHES AND THE
ICWW CORRIDOR. THUS LOOK FOR MINIMUMS IN MANY SPOTS POTENTIALLY TO
OCCUR AROUND OR JUST AFTER MIDNIGHT BEFORE LEVELING OFF INTO THE WEE
HOURS OF SUNDAY...AS H5-H6 CLOUDS THICKEN AND LIGHT S-SW WINDS
PREVAIL.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...RETURN FLOW GETS UNDERWAY ON SUNDAY ALBEIT
PERHAPS SLOWER THAN PREVIOUSLY THOUGHT AS IT MAY BE LATER IN THE
DAY. MOST OF THE RETURN FLOW WILL GO TO INCREASING CLOUDS RATHER
THAN ACTUAL RAIN CHANCES WHICH SHOULD HOLD OFF UNTIL NIGHTTIME.
WARMER AIR MOVING INTO THE REGION WILL ALSO BRING ABOUT SOME WELCOME
SEASONABLE HIGH TEMPERATURES. AS THE RAINFALL CHANCES RAMP UP IN THE
STRENGTHENING WE MAY SEE TEMPERATURES NEARLY FLAT OR EVEN RISING
OVER SUNDAY NIGHT WITH LOW TEMPERATURES FAIRLY CLOSE TO SEASONABLE
HIGHS AND THE NIGHT WILL GROW INCREASINGLY BREEZY AS THE LOW LEVEL
JET REALLY RAMPS UP IN STRENGTH. SIMILARLY MONDAY WILL BE QUITE
BREEZY WITH SHOWERS THAT WILL BE OF MODERATE INTENSITY. ALL TOLD
SOME AREAS COULD NET A HALF INCH OF PRECIP. MONDAY MAY FEATURE A
SECOND PERIOD OF NON-DIURNAL TEMPERATURE CURVE AS THE MIDDAY FROPA
LEADS TO AFTERNOON FALLING TEMPERATURES. BACK TO REALITY MONDAY
NIGHT WITH TEMPERATURES NEAR OR BELOW THEIR SEASONABLE NORMS.


&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 3 PM SATURDAY...UNCERTAINTY REMAINS PROMINENT DURING THE
PERIOD CONCERNING THE EVOLUTION OF SOUTHERN STREAM SYSTEM NEXT WEEK.
WHILE CONFIDENCE IN THE SOUTHERN STREAM FEATURE DEVELOPING IS QUITE
HIGH THE EXTENT OF ITS INTERACTION WITH A NORTHERN STREAM SHORTWAVE
MID TO LATE WEEK REMAINS UNCLEAR. LATEST GFS/CMC CONTINUE TO SHOW
INTERACTION OF THESE 2 FEATURES WITH UNSETTLED WEATHER ACROSS THE
SOUTHEAST THU AS THE LOW MOVES UP THE COAST AND THEN FRI AS THE 5H
TROUGH MOVES OVERHEAD. IN ADDITION THIS SOLUTION HAS SUPPORT FROM A
LITTLE MORE THAN HALF OF THE GFS ENSEMBLE MEMBERS. ON THE OTHER HAND
THE ECMWF PAINTS A MUCH DRIER PICTURE. IT HAS LIMITED INTERACTION
BETWEEN THE NORTHERN AND SOUTHERN STREAM SYSTEMS AND MOVES THE 5H
FEATURE AND THE SURFACE LOW ACROSS THE FL PENINSULA. IT IS WORTH
NOTING THAT WITH THE LAST SYSTEM...THE NORTHEAST BLIZZARD EARLIER
THIS WEEK...THERE WAS DISAGREEMENT BETWEEN THE GUIDANCE AND AT THE 5
DAY MARK THE CMC ENDED UP BEING PRETTY CLOSE.

NOT PLANNING MUCH IN THE WAY OF CHANGES FOR NOW GIVEN THE LARGE
AMOUNT OF UNCERTAINTY LATE IN THE PERIOD. UNTIL THE NORTHERN STREAM
SHORTWAVE IS ASSESSED BY THE UPPER AIR NETWORK GUIDANCE WILL LIKELY
CONTINUE TO STRUGGLE WITH THE TIMING...STRENGTH...AND TRACK OF THE
SYSTEM. EITHER WAY TEMPERATURES ARE GOING TO BE GENERALLY AT OR
BELOW CLIMO THROUGH THE PERIOD WITH HIGHS POTENTIALLY WELL BELOW
CLIMO MID TO LATE WEEK.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
AS OF 00Z...VFR EXPECTED THROUGH THIS TAF VALID PERIOD. EVEN THOUGH
WINDS ARE CURRENTLY S 6-8 KT AT KCRE/KMYR...A STRONG INVERSION WILL
CAUSE WINDS TO BE LIGHT AND VARIABLE THROUGH SUNRISE. TAFS REFLECT
LOWEST POSSIBLE CEILINGS OF 13K THROUGH 18Z. ACTUAL CEILINGS MAY NOT
DEVELOP UNTIL AFTER 09Z AND MAY BE HIGHER AND OF SHORTER DURATION.
FROM 16-18Z WINDS BECOME S AROUND 10 KT AS CEILINGS IMPROVE TO 20K
OR SO.

EXTENDED AVIATION OUTLOOK...SHOWERS/MVFR LIKELY LATE SUN THROUGH MON
MORNING...THEN BECOMING VFR AGAIN THROUGH WED. POSSIBLE RAIN THURS.

&&

.MARINE...
NEAR TERM/THROUGH TONIGHT/...
AS OF 930 PM SATURDAY...LATEST HIGH-RES MODELS SHOW A DELAY IN THE
ONSET OF W WINDS UNTIL AFTER MIDNIGHT. BESIDES THIS MINOR CHANGE THE
PREVIOUS FORECAST REMAINS INTACT. DISCUSSION FROM 630 PM FOLLOWS...

ONLY TWO CHANGES WERE MADE TO THE FORECAST AND BOTH DEAL WITH
NEARSHORE EFFECTS: THE REMNANT AFTERNOON SEABREEZE CIRCULATION MAY
TAKE ANOTHER HOUR OR TWO TO DIE AWAY GIVEN CURRENT OBSERVATIONS OF
SOUTH WINDS NEAR 10 KNOTS AT THE BEACHES. ALSO...NEARSHORE SEAS WERE
A LITTLE HIGH IN THE PREVIOUS FORECAST BASED ON 6:00 PM DATA FROM
THE SUNSET BEACH NEARSHORE BUOY OF 1 FOOT SEAS IN A 9 SECOND PERIOD.
OTHERWISE NO SIGNIFICANT CHANGES WERE MADE TO THE FORECAST.
DISCUSSION FROM 300 PM FOLLOWS...

A VASTLY IMPROVING MARINE ENVIRONMENT INDEED MATEYS...AS SURFACE
HIGH PRESSURE PARKS OVER THE WATERS AND WINDS DIE OUT TO 10 KT OR
LESS OVERNIGHT. THE BULK OF WAVE ENERGY HAS BEEN LINKED WITH WINDS
SO AS WINDS TAIL OFF...SEA HEIGHT WILL AND PRESENTLY ARE SUBSIDING.
2-4 FOOT SEAS LATE THIS AFTERNOON WILL FALL TO 2-3 FT THIS EVENING
TO 1.5-2 FT INTO FIRST LIGHT SUNDAY WITH LIGHT WIND. THIS WILL
LIKELY ALLOW E WAVES OF 1-1.5 FT EVERY 9-10 SECONDS TO BECOME THE
DOMINANT WAVE ACTION IN GENTLE ROLLING SWELL. NO TSTMS OR
RESTRICTIONS TO VISIBILITY ARE EXPECTED THROUGH TONIGHT.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...VERY UNSETTLED FOR ALL BUT THE VERY START OF
THE PERIOD. THIS RELATIVE CALM COMES THROUGH MIDDAY SUNDAY AS HIGH
PRESSURE INITIALLY JUST OFFSHORE MOVES A BIT FURTHER OUT TO SEA.
THIS ALLOWS FOR A BROAD SWATH OF SWRLY RETURN FLOW TO SET UP ALL
ALONG THE EAST COAST. SUNDAY NIGHT INTO MONDAY WARM AND MOIST AIR
WILL STREAM INTO THE SOUTHEAST IN THIS RETURN FLOW REGIME. MEANWHILE
AN UPPER DISTURBANCE AND SURFACE COLD FRONT APPROACH FROM THE
NORTHWEST. A SMALL CRAFT ADVISORY IS EXPECTED FOR BOTH WIND AND
SEAS...EASILY. THE MAIN QUESTION IS WHETHER OR NOT GALES WILL OCCUR
AND BE FREQUENT ENOUGH THAT A GALE WARNING WILL BE NEEDED. AT THIS
TIME A GALE WATCH COULD BE HOISTED BUT AFTER COLLAB WITH NEIGHBORING
WFOS HAVE ELECTED TO HOLD OFF FOR NOW. THE TWO MAIN ISSUES THAT MAY
PRECLUDE GALES ARE: 1.THE STRONGER LOW LEVEL WIND FIELDS ON THE WRF
MAY BE OVERDONE AND 2. THE COOL SSTS WILL REALLY INHIBIT VERTICAL
MIXING IN THIS OTHERWISE WARM AIRMASS. SOME PRETTY STRONG WINDS MAY
BE LURKING JUST OFF THE DECK BUT MAY HAVE TROUBLE REACHING THE
SURFACE...WITH ANY REGULARITY. REGARDLESS IT LOOKS LIKE HAZARDOUS
CONDITIONS PERSIST AND A MIDDAY OR EARLY PM FROPA WILL ADD A
STEEPENING ELEMENT OF CONFUSION TO WAVE FACES DUE TO ABRUPT WIND
SHIFT.

LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 3 PM SATURDAY...SURFACE HIGH BUILDING IN FROM THE WEST TUE
WILL MOVE OVERHEAD AND OFFSHORE TUE NIGHT AND WED. PINCHED GRADIENT
INITIALLY WILL HAVE NORTHEAST FLOW IN THE 15 TO 20 KT RANGE BUT
GRADIENT IS QUICK TO RELAX AND BY MIDDAY NORTHEAST FLOW WILL BE 10
KT OR LESS. LIGHT AND VARIABLE WINDS TUE NIGHT BECOME SOUTHERLY ON
WED. EARLY THU WINDS VEER TO NORTHERLY AS COLD FRONT MOVES ACROSS
THE WATERS. STILL SOME UNCERTAINTY LATE IN THE PERIOD BUT NEARLY ALL
OF THE SOLUTIONS DO SHOW MODERATE TO STRONG NORTHERLY FLOW
DEVELOPING THU INTO THU NIGHT. HEADLINES MAY BE REQUIRED LATE IN THE
PERIOD. LIGHT AND VARIABLE WINDS WILL KEEP SEAS 2 TO 3 FT TUE AND
WED WITH AN INCREASE EXPECTED LATE IN RESPONSE TO INCREASED WIND
SPEEDS.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 1 AM MONDAY TO 1 AM EST TUESDAY
FOR      AMZ250-252-254-256.

&&

$$

NEAR TERM...MJC/TRA
SHORT TERM...MBB
LONG TERM...III
AVIATION...MRR




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