463
FXUS62 KILM 201735
AFDILM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
135 PM EDT SAT APR 20 2019
SYNOPSIS
LOW PRESSURE ALOFT OVER THE TENNESSEE VALLEY WILL SLOWLY CROSS
THE MID-ATLANTIC STATES SUNDAY THEN MOVE OFFSHORE MONDAY. HIGH
PRESSURE WILL BUILD OVER THE SOUTHEAST FROM THE WEST LATER TODAY
THROUGH SUNDAY, SHIFTING OVERHEAD MONDAY. THE HIGH WILL LINGER
THROUGH THE MIDDLE OF THE WEEK BEFORE SHIFTING OFFSHORE LATE IN
THE WEEK AS THE NEXT SYSTEM APPROACHES FROM THE WEST.
NEAR TERM /THROUGH SUNDAY/
AS OF 10 AM SATURDAY...SHORTWAVE AND ASSOCIATED MOISTURE
ROTATING AROUND THE BASE OF THE 5H LOW, OVER THE TN VALLEY THIS
MORNING, WILL LEAD TO SCATTERED SHOWERS THIS AFTERNOON. THE
QUESTION IS WILL THESE SHOWERS MOVE INTO THE FORECAST AREA OR
SKIRT THE AREA TO THE NORTHWEST. DID INTRODUCE A SLIGHT CHANCE
POP FOR NORTHWEST CORNER OF THE FORECAST AREA WITH THE UPDATE
BASED ON CURRENT SATELLITE/RADAR TRENDS. FURTHER EXPANSION OF
SHOWER COVERAGE MAY BE REQUIRED WITH THE EARLY AFTERNOON UPDATE.
OTHER THAN FIGURING OUT HOW CLOSE THE COLD POOL AND MOISTURE
WILL BE TO THE AREA THE FORECAST IS PRETTY STRAIGHT FORWARD.
STEEP LOW LEVEL LAPSE RATES AND INCREASE AFTERNOON CLOUD,
ESPECIALLY INLAND, WILL LIMIT WARMING TODAY AND, COUPLED WITH
COLD ADVECTION, WILL KEEP TEMPERATURES BELOW TO WELL BELOW
CLIMO.
SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/
AS OF 300 AM SATURDAY...THERMAL ADVECTION TURNS NEUTRAL
SUNDAY NIGHT BUT AFTER THE COOL PRECEDING DAY LOW TEMPERATURES
WILL END UP A FEW DEGREES BELOW CLIMATOLOGY. THIS HOLDS TRUE
HEADING INTO MONDAY BUT SOLAR MODIFICATION OF THE AIRMASS WILL
BRING AN AFTERNOON THAT IS A FEW DEGREES ABOVE CLIMO. THERE
WILL BE SOME WEAK WARM ADVECTION MONDAY NIGHT BUT WITH THE HIGH
CENTER SO CLOSE IT WILL NOT MIX TO THE SURFACE. SO ONCE AGAIN
MONDAY NIGHT TEMPS RIGHT NEAR NORMAL.
LONG TERM /TUESDAY THROUGH FRIDAY/
AS OF 300 AM SATURDAY...SURFACE HIGH PRESSURE THAT MOVES EAST
ACROSS THE AREA TUESDAY INTO WEDNESDAY WILL BE WEAK AND POORLY
DEFINED KEEPING WINDS VERY LOW AND WARM ADVECTION SOMEWHAT
MINIMIZED. THE WARMING TREND ONGOING WILL BE MORE TIED TO SOLAR
MODIFICATION OF THE AIRMASS. THURSDAY NO LONGER APPEAR TO OFFER
THE CHANCE FOR BACKDOOR COLD FRONT RELATED SHOWERS AS THE
BOUNDARY NOW STAYS MUCH FURTHER TO OUR NORTH. MOISTURE WILL BE
INCREASING HOWEVER AS A SOUTHERN BRANCH FEATURE APPROACHES FROM
THE WEST. THIS FEATURE WILL INTRODUCE RAIN CHANCES ON FRIDAY.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
AS OF 18Z...UPPER LOW WILL MOVE SLOWLY NORTHEAST THROUGH THE
FORECAST PERIOD. STEEP LAPSE RATES HAVE SPAWNED A LOT OF CU. ANY
PRECIP WILL LIKELY BE NORTH OF OUR CWA, HOWEVER LBT COULD SEE A
BRIEF SHOWER AROUND MAX HEATING. WINDS WILL BE PREDOMINATELY
OFFSHORE. LIGHT WINDS TONIGHT AND SUNDAY.
EXTENDED OUTLOOK...VFR CONDITIONS THRUOUT THE EXTENDED AS THE CENTER
OF HIGH PRESSURE PARKS ACROSS THE EASTERN CAROLINAS.
POTENTIAL FOR MVFR FROM MORNING FOG TUE AND WED MORNINGS.
MARINE
AS OF 10 AM SATURDAY...STRONG SMALL CRAFT ADVISORY CONTINUES FOR
ALL ZONES WITH POTENTIAL FOR GUSTS APPROACHING 30 KT THIS
AFTERNOON. WINDS WILL GRADUALLY WEAKEN LATE TODAY INTO TONIGHT
AS COLD ADVECTION ABATES AND GRADIENT RELAXES. ONLY MINIMAL
CHANGES WITH MORNING UPDATE.
WIND SPEEDS WILL DROP BELOW SCA THRESHOLDS TONIGHT AND
CONTINUING THE DIMINISHING TREND ON SUN. SIGNIFICANT SEAS WILL
BE SLOW TO SUBSIDE GIVEN THE SWELL GENERATED JUST OFFSHORE
BLEEDING INTO THE LOCAL WATERS. SW TO WSW WIND DRIVEN WAVES WILL
MESH ON TOP OF THIS SWELL. SCA THRESHOLD SEAS WILL PERSIST THRU
TONIGHT AND POSSIBLY A GOOD PORTION OF SUN.
ADVISORY FLAGS SHOULD BE ABLE TO BE DROPPED SUNDAY NIGHT AS HIGH
PRESSURE BUILDING IN BRINGS LIGHT NW WINDS AND DECREASING SEAS.
WITH THE HIGH BOTH POORLY DEFINED AND MOVING OVERHEAD MONDAY AND
MONDAY NIGHT WINDS WILL BE CAPPED AT 10KT AND EXHIBIT SOME
INCONSISTENCY IN DIRECTION.
HIGH PRESSURE WILL BE FOUND OFF THE COAST THROUGH THE PERIOD.
THIS WILL PROMOTE A GENERALLY SOUTHWESTERLY FLOW. THE HIGH WILL
REMAIN WEAK AND KEEP WINDS AROUND JUST 10KT. SEAS WILL AVERAGE
2-3 FEET.
ILM WATCHES/WARNINGS/ADVISORIES
SC...NONE.
NC...HIGH RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR NCZ106-
108.
HIGH RIP CURRENT RISK UNTIL 9 PM EDT THIS EVENING FOR NCZ110.
BEACH HAZARDS STATEMENT UNTIL 8 PM EDT THIS EVENING FOR NCZ110.
MARINE...SMALL CRAFT ADVISORY UNTIL NOON EDT SUNDAY FOR AMZ250-252-254-
256.
SYNOPSIS...DCH
NEAR TERM...III
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...DL
MARINE...
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