572
FXUS62 KILM 232246
AFDILM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
545 PM EST SAT FEB 23 2019
SYNOPSIS
HIGH PRESSURE TO THE NORTH WILL SHIFT OFF THE COAST OVERNIGHT,
LIFTING A WARM FRONT ACROSS THE WATERS. SOUTHERLY WINDS INCREASE
LATE TONIGHT AND SUNDAY AHEAD OF A COLD FRONT THAT CROSSES THE
AREA SUNDAY EVENING. HIGH PRESSURE WILL THEN BUILD OVER THE
REGION FROM THE NORTHWEST THROUGH WEDNESDAY WITH CHANCES OF RAIN
INCREASING LATE WEDNESDAY INTO FRIDAY.
NEAR TERM /THROUGH SUNDAY NIGHT/
AS OF 3 PM SATURDAY...FRONT STALLED SOUTH OF THE AREA WILL LIFT
NORTH THROUGH THE EVENING AND OVERNIGHT AS SURFACE HIGH TO THE NORTH
SHIFTS OFF THE COAST. FRONT IS NOT EXPECTED TO HAVE MUCH, IF ANY,
RAINFALL WITH IT AS IT LIFTS NORTH. INCREASING SOUTHERLY FLOW IN THE
WAKE OF THE EXITING FRONT WILL LEAD TO SLOWLY RISING TEMPS
OVERNIGHT. LOWS WILL END UP WELL ABOVE CLIMO WITH MANY AREAS LIKELY
TO EXPERIENCE SAT HIGHS AND SAT NIGHT LOWS AT THE SAME TIME. PRECIP
CHANCES OVERNIGHT ARE LESS CERTAIN. THERE IS AN ABUNDANCE OF LOW-
LEVEL MOISTURE, ALTHOUGH THIS IS RELATIVELY SHALLOW. ALMOST NO LIFT
OR FORCING WILL BE PRESENT AND FORECAST SOUNDINGS CONTINUE TO SHOW
AT LEAST SOME MID-LEVEL SUBSIDENCE HOLDING ON. HIGH RESOLUTION SHORT
TERM GUIDANCE HAD BEEN SHOWING SOME WEAK CONVERGENCE MOVING INTO THE
AREA OVERNIGHT, BUT HAS BACKED OFF ON THE STRENGTH OF THIS. THE
SIGNAL LOOKED A LOT LIKE FEEDBACK ISSUES FROM CONVECTION IN THIS
MORNING RUNS AND WEAKENING OF THE ACTIVITY IN FURTHER RUNS IS NOT
UNEXPECTED. PLAN TO MAINTAIN SLIGHT CHANCE POP OVERNIGHT. BETTER
RAIN CHANCES WILL BE ON SUN AS THE COLD FRONT CROSSES THE AREA.
STRONG WARM ADVECTION OVERNIGHT WILL LIKELY RESULT IN FOG DEVELOPING
ACROSS MUCH OF THE AREA.
COLD FRONT MOVING ACROSS THE AREA SUN WILL BE MOVING INTO A
WARM/MOIST AIRMASS. FORECAST SOUNDINGS SUGGEST CAPE COULD BE IN 500-
600 J/KG RANGE FOR A PERIOD, RIGHT AHEAD OF THE FRONT. THIS IS ALSO
WHERE PRECIPITABLE WATER JUMPS TO AROUND 1.6 INCHES. ALTHOUGH THE
PARENT LOW MOVES THROUGH THE GREAT LAKES, KEEPING THE DYNAMICS WELL
NORTH OF THE AREA, STRONG CONVERGENCE ALONG THE FRONT AND THE
AFOREMENTIONED INSTABILITY SHOULD LEAD TO A LINE OF BROKEN
CONVECTION. LESS CONFIDENT IN PROSPECTS FOR THUNDER WITH THE LINE.
THERE IS MID-LEVEL DRY AIR (EVEN DURING THE TIMES OF HIGHEST DEEPER
MOISTURE) AND LAPSE RATES IN THE CHARGE SEPARATION ZONE ARE VERY
WEAK. THERE MAY NOT BE ENOUGH UPWARD MOTION TO GENERATE SUFFICIENT
CHARGE SEPARATION. AT THIS POINT DO NOT HAVE THUNDER IN THE
FORECAST, BUT CANNOT RULE OUT AN ISOLATED RUMBLE. STRONG WARM
ADVECTION AHEAD OF THE FRONT WILL LEAD TO TEMPERATURES WELL ABOVE
CLIMO, WITH HIGHS LIKELY OCCURRING AROUND MIDDAY FOR WESTERN
PORTIONS OF THE FORECAST AREA.
HIGH PRESSURE BUILDS IN BEHIND THE RAPIDLY EXITING FRONT LATE SUN
INTO SUN EVENING. STRONG/DEEP WEST-NORTHWEST FLOW HELPS DRY OUT THE
REGION SUN NIGHT INTO MON BUT DOES NOT REALLY PRODUCE ANY STRONG
COLD ADVECTION. TEMPS DROP SUN NIGHT, BUT ONLY A SMALL PORTION OF
THE DROP IS DUE TO COLD ADVECTION WITH THE BULK OF THE COLD AIR
TRAPPED WELL NORTH OF THE AREA.
SHORT TERM /MONDAY THROUGH MONDAY NIGHT/
AS OF 330 PM SATURDAY...DRY WEATHER FOR THE SHORT TERM PERIOD
AS SURFACE HIGH PRESSURE BUILDS IN FROM THE NORTHWEST. WITH VERY
LITTLE MOISTURE IN THE ZONAL FLOW ALOFT, EXPECT A MAINLY
SUNNY/CLEAR SKY. TEMPS WILL BE CLOSE TO NORMAL FOR LATE
FEBRUARY...HIGHS MONDAY IN THE LOW 60S, WITH LOWS MONDAY NIGHT
35-40.
LONG TERM /TUESDAY THROUGH SATURDAY/
AS OF 330 PM SATURDAY...CONTINUED DRY TO START OFF THE LONG
TERM PERIOD WITH SURFACE HIGH PRESSURE SLIDING OFFSHORE. THERE
WILL BE A GENERAL TREND TOWARDS INCREASING CHANCES OF RAIN LATE
IN THE WEEK AS MOISTURE INCREASES, HOWEVER A STRONG HIGH TO THE
N/NE (E.G. 12Z ECMWF) COULD DELAY PRECIP CHANCES. CAPPED POPS AT
30% FOR NOW WITH A LOT OF UNCERTAINTY OVER THE TIMING OF
PRECIP. TEMPS WILL CONTINUE NEAR NORMAL...HIGHS IN THE UPR 50S
TO MID 60S EACH DAY.
AVIATION /00Z SUNDAY THROUGH THURSDAY/
AS OF 00Z....A SCENARIO IS SETTING UP WHERE DENSE FOG IS IN PLAY.
WARM AIR ADVECTION JUST OFF THE DECK WILL KEEP TEMPS NEAR STEADY,
PERHAPS WARMING AFTER MIDNIGHT. DEWPOINTS WILL RISE AS WELL, WITH
SOME POSSIBLE VLIFR FOG POSSIBLE AFTER 04Z.
TOWARD MORNING, SOUTHERLY FLOW WILL INCREASE AS A WARM FRONT RIDES
NORTH OF THE CWA. AT SOME POINT THE WINDS WILL BE STRONG ENOUGH TO
MIX OUT THE FOG, PROBABLY AFTER DAYBREAK. LOOK FOR GUSTY SOUTHWEST
WINDS WITH SOME LIGHT SCATTERED CONVECTION POSSIBLE BY MID MORNING.
EXTENDED OUTLOOK...VFR LATE SUNDAY THROUGH EARLY WEDNESDAY. POSSIBLE
SUB-VFR LATE WEDNESDAY AND THURSDAY.
MARINE
AS OF 3 PM SATURDAY...EASTERLY WINDS THIS EVENING WILL BECOME
SOUTHERLY OVERNIGHT AS FRONT LIFTS NORTH OF THE WATERS. SOUTH TO
SOUTHWEST FLOW IN THE WAKE OF THE FRONT WILL START TO INCREASE LATE
TONIGHT AND SUN AS THE GRADIENT TIGHTENS AHEAD OF AN APPROACHING
COLD FRONT. AHEAD OF THE FRONT WINDS WILL BE 20 TO 25 KT, BUILDING
SEAS TO 5 TO 7 FT AS EARLY AS MIDDAY SUN. BOTH WINDS AND SEAS ARE
LIKELY TO WARRANT SMALL CRAFT ADVISORY CONTINUING THROUGH AT LEAST
SUN NIGHT WITH FLOW IN THE WAKE OF THE FRONT BECOMING OFFSHORE.
SPEEDS WILL REMAIN 20 TO 25 KT SUN NIGHT WHILE THE OFFSHORE
TRAJECTORY HELPS DROP SEAS FROM 4 TO 6 FT IN THE EVENING TO 2 TO 4
FT BY MON MORNING.
SUB-SMALL CRAFT ADVISORY CONDITIONS EARLY TO MID NEXT WEEK WITH
HIGH PRESSURE OVER THE WATERS. WINDS MAINLY UNDER 10 KT WITH 1-2
FT SEAS, BEFORE SOME INCREASE INTO WEDNESDAY...10-15 KT NE WINDS
WITH 2-3 FT SEAS.
ILM WATCHES/WARNINGS/ADVISORIES
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON SUNDAY TO 7 AM EST MONDAY FOR
AMZ250-252-254-256.
SYNOPSIS...MAS
NEAR TERM...III
SHORT TERM...MAS
LONG TERM...MAS
AVIATION...43
MARINE...III/MAS
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