420
FXUS62 KILM 180153
AFDILM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
953 PM EDT SAT APR 17 2021
SYNOPSIS
WEAK HIGH PRESSURE WILL KEEP THE AREA DRY THROUGH THE REMAINDER
OF THE WEEKEND. WEAK LOW PRESSURE MOVING SOUTH OF CAPE FEAR WILL
BRING SMALL RAIN CHANCES EARLY MONDAY. A DRY COLD FRONT WILL
CROSS THE COAST LATE WEDNESDAY, WITH COOLER HIGH PRESSURE MOVING
IN THURSDAY AND FRIDAY. A STORM SYSTEM WILL APPROACH FROM THE
GULF COAST STATES ON SATURDAY, AND RAIN CHANCES WILL INCREASE.
UPDATE
NO CHANGES THIS UPDATE.
NEAR TERM /THROUGH SUNDAY NIGHT/
A WEAK POCKET OF SHORTWAVE ENERGY ALONG THE FLORIDA PANHANDLE WILL
CONTINUE TO PROGRESS ENE OVERNIGHT. THIS ENERGY HAS SPAWNED THE
DEVELOPMENT OF A SERIES OF WEAK LOW PRESSURE SYSTEMS (PROBABLY
BETTER DESCRIBED AS WEAK WAVES OF LOW PRESSURE), MOVING OF THE GA
COAST AND PROGRESSING OFFSHORE OVERNIGHT. THE FINALE OF THESE
SYSTEMS MAY BRING ISOLATED SHOWERS ALONG THE SC OR EXTREME SOUTHERN
NC COASTLINE TONIGHT. SOUNDINGS AND ASSOCIATED SATELLITE IMAGERY
SHOW DRY AIR IN THE LOW-LEVELS WHICH WILL INHIBIT SHOWER DEVELOPMENT
ON A SCATTERED OR WIDESPREAD SCALE. IF ANY SHOWERS DEVELOP, EXPECT
ONLY A SMALL AMOUNT OF QPF IF ANY AT ALL (LESS THAN A TENTH OF AN
INCH). CLOUDS OVERNIGHT WILL IMPACT TEMPERATURES WITH LOWS SCHEDULED
IN THE MID 50S INLAND TO UPPER 50S ALONG THE COAST.
ON SUNDAY, WEAK SURFACE LOW PRESSURE AND ANY UPPER-LEVEL ENERGY WILL
CONTINUE TO PUSH OFFSHORE AS SHOWER CHANCES COME TO AN END. MOST OF
THE DAY WILL REMAIN DRY WITH A GOOD AMOUNT OF CLOUD COVERAGE.
SOUNDINGS CONTINUE TO SHOW DRY AIR THROUGHOUT THE LOW-LEVELS, BUT
LINGERING MOISTURE IN THE MID-LEVELS NEAR A SUBSIDENCE INVERSION IS
LIKELY TO HANG AROUND THROUGH MUCH OF THE DAY. COULD SEE A FEW PEEKS
OF SUNSHINE DURING THE AFTERNOON AS DRY AIR STARTS TO DESCEND AND
ERODES SOME OF THE THINNING CLOUD COVER. HIGHS SHOULD REMAIN RIGHT
AROUND NORMAL: IN THE MID-70S. STRONGER SHORTWAVE WILL APPROACH THE
AREA FROM THE WEST SUNDAY NIGHT INTO EARLY MONDAY. THE BEST FORCING
AND ASSOCIATED RAIN CHANCES WILL STAY TO OUR NORTH NEAR THE
VORTICITY MAXIMUM OVER NORTHERN NC AND SOUTHERN VA. MOISTURE AGAIN
APPEARS TO BE LIMITED WITH THIS SYSTEM, BUT THE BETTER FORCING MAY
REQUIRE SLIGHTLY HIGHER POPS THROUGH MONDAY MORNING. OVERNIGHT LOWS
IN THE LOW 50S WITH MID 50S ALONG THE COAST.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
PROGRESSIVE MID-LEVEL FLOW OVER THE AREA WILL PUSH A WEAK SURFACE
TROUGH/LOW OFF THE COAST EARLY MONDAY, FOLLOWED BY A LIGHT NORTHERLY
BREEZE. MAY SEE A FEW LIGHT SHOWERS MONDAY MORNING, HOWEVER MOISTURE
IS A LIMITING FACTOR, AND IT'S CONFINED BELOW ABOUT 800 MB. A LOW-
AMPLITUDE 500 MB RIDGE WILL TRAVERSE THE AREA MONDAY NIGHT, AND
SURFACE WINDS WILL VEER TO THE EAST AS SURFACE HIGH PUSHES OFF
THE NC/VA COAST. MID-LEVEL MOISTURE WILL INCREASE TUESDAY AS
SYNOPTIC FLOW TURNS SW AHEAD OF A BROAD TROUGH SWINGING ACROSS
THE CENTRAL PLAINS. DEEPENING SURFACE LOW WILL LIFT ACROSS THE
OHIO RIVER VALLEY TUESDAY NIGHT, AND ASSOCIATED SURFACE COLD
FRONT WILL CROSS THE APPALACHIANS INTO THE WESTERN CAROLINAS
LATE TUESDAY NIGHT. FORCING WILL BE WEAK BUT COULD SEE A FEW
SHOWERS POP UP TUESDAY AFTERNOON INTO THE EVENING. MAX TEMPS
THIS PERIOD SHOULD BE WITHIN A COUPLE OF DEGREES OF NORMAL FOR
MID APRIL (MID 70S). LOW TEMPS MONDAY NIGHT WILL ALSO BE CLOSE
TO NORMAL (LOW-MID 50S), THEN A COUPLE OF DEGREES WARMER TUESDAY
NIGHT WITH ONSHORE FLOW.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
A BROAD MID/UPPER TROUGH WILL SHIFT EAST OF THE MISSISSIPPI RIVER
VALLEY WEDNESDAY, WITH A WEAK EMBEDDED 500 MB SHORTWAVE MAKING ITS
WAY OFF THE COAST LATE THURSDAY AFTERNOON OR EARLY THURSDAY EVENING.
THE ASSOCIATED SURFACE LOW WILL LIFT ACROSS THE NORTHEAST CONUS
WEDNESDAY NIGHT, AND A RESPECTABLE COLD FRONT WILL PUSH ACROSS THE
AREA EASTERN CAROLINAS WEDNESDAY AFTERNOON. MOISTURE WILL BE
LACKING, SO POPS, IF ANY, ON WEDNESDAY WILL BE MINIMAL. COOL HIGH
PRESSURE WILL BUILD IN WEDNESDAY NIGHT AND THURSDAY, WITH A
SECONDARY DRY COLD FRONT EXPECTED TO PUSH ACROSS THE AREA THURSDAY
EVENING. THE NEXT SYSTEM WILL BE PUSHING ACROSS THE GULF COAST
STATES FRIDAY NIGHT INTO SATURDAY, RESULTING IN INCREASING POPS FROM
SW TO NE DURING THE DAY.
AVIATION /02Z SUNDAY THROUGH THURSDAY/
VFR, BUT WITH CLOUDS ABUNDANT TONIGHT AND EARLY SUNDAY ABOVE
8000 FEET, AS A STREAM OF RAIN PASSES OFFSHORE OF GEORGIA AND
SOUTHERN SOUTH CAROLINA. CLOUDS TO DECREASE FOR THE LAST 12
HOURS OF TAF CYCLE DURING SUNDAY, WITH FEW/SCT150 BY MID-
AFTERNOON. A WEAK SHIFT IS EXPECTED TONIGHT BETWEEN 6-9Z, BUT
WINDS ARE SO LIGHT THAT THE CHANGE IN WIND DIRECTION WILL HAVE
LITTLE IMPACT ON AVIATION.
EXTENDED OUTLOOK...VFR, WITH OCCASIONAL MIDDLE AND HIGH CLOUDS
AS SEVERAL WEAK WAVES TRAVERSE THE REGION. A MODERATELY STRONG
COLD FRONT WEDNESDAY NIGHT MAY BRING RESTRICTIONS.
MARINE
THROUGH SUNDAY NIGHT: WINDS REMAIN LIGHT AND VARIABLE
THROUGHOUT THE NEAR-TERM PERIOD. SOUTHERLY WINDS THIS EVENING
AROUND 10 KNOTS WILL BECOME NW BEHIND AN EXITING SURFACE LOW BY
SUNDAY MORNING. AFTER A BRIEF PERIOD OF OFFSHORE WINDS ON
SUNDAY, WINDS BECOME SW AHEAD OF THE NEXT WEAK WAVE OF LOW
PRESSURE TRAVERSING THE APPALACHIANS ON SUNDAY NIGHT. WAVES
THROUGHOUT THE PERIOD MAINTAIN AROUND 2 FEET DUE TO THE VARIABLE
WINDS WITH NO SIGNIFICANTLY BUILDING WAVE ENERGY.
MONDAY THROUGH THURSDAY: A WEAK SURFACE TROUGH OVER THE AREA WATERS
MONDAY WILL LEAD TO VARIABLE WINDS GENERALLY 10 KTS OR LESS. ENE
WINDS WILL DEVELOP LATE MONDAY AFTERNOON INTO THE EVENING AS THE LOW
SLIDES EAST AND WEAK HIGH PRESSURE MOVES OFF THE NC/VA COAST. WIND
SPEEDS WILL REMAIN RELATIVELY LIGHT, WITH AN ONSHORE COMPONENT,
THROUGH TUESDAY, BECOMING S-SW TUESDAY NIGHT AHEAD OF A COLD FRONT.
SPEEDS WILL INCREASE TUESDAY NIGHT AND WEDNESDAY AS THE FRONT
CROSSES THE CAROLINAS, AND IT WILL MOVE ACROSS THE WATERS IN THE
WEDNESDAY EVENING TIME FRAME. A STRONG POST-FRONTAL GRADIENT LOOKS
TO PUSH NW WINDS TO 20-25 KTS WEDNESDAY NIGHT. THE GRADIENT WILL
RELAX BY THURSDAY MORNING, AND ALTHOUGH WINDS WILL REMAIN WNW,
SPEEDS SHOULD FALL TO 10-15 KTS.
ILM WATCHES/WARNINGS/ADVISORIES
SC...NONE.
NC...NONE.
MARINE...NONE.
UPDATE...8
NEAR TERM...21
SHORT TERM...CRM
LONG TERM...CRM
AVIATION...MJC
MARINE...21/CRM
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