000
FXUS62 KILM 131127
AFDILM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
628 AM EST SAT MAR 13 2010
.SYNOPSIS...
LOW PRESSURE OVER THE MID-ATLANTIC STATES WILL DRIFT TOWARD THE EAST
THROUGH EARLY NEXT WEEK...MAINTAINING WESTERLY WINDS AND SEASONABLE
TEMPERATURES. COOLER AIR AND POSSIBLY A FEW SHOWERS MAY ARRIVE MID
TO LATE WEEK...AS LOW PRESSURE ALOFT TRACKS ACROSS THE REGION.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM SATURDAY...IMAGERY FROM SPACE THIS MORNING IS DOMINATED
BY A LARGE UPPER LOW SWIRLING OVER THE CENTRAL MISSISSIPPI VALLEY.
INGESTING ACROSS THE SOUTHERN AND EASTERN FLANK OF THIS MAMMOTH
CYCLONIC CIRCULATION ALOFT IS DRY MID LEVEL AIR WITH SHORT WAVE
ENERGY OFFSHORE EJECTING RAPIDLY NORTHWARD. A SURFACE LOW POSITIONED
OVER WAKEFIELD VA THIS MORNING WILL MEANDER AND WOBBLE BUT MOVE
LITTLE OVERALL TODAY AS HEIGHT FALL CHANGES ALOFT EVOLVE SLOWLY.
THIS WILL IMPART MODERATE WSW WIND FLOW ACROSS THE FORECAST AREA
TODAY WHILE A MID LEVEL CAP OVERSPREADS THE REGION.
A MILD MID-MARCH SATURDAY ON TAP WITH LITTLE COLD AIR ADVECTION AND
DOWNSLOPE FLOW ANTICIPATED. WE MAY SEE A FEW READINGS AROUND 70
DEGREES THIS AFTERNOON UNDER A SUNNY START. SHALLOW CONVECTIVE
SHOWERS COULD FIRE THIS AFTERNOON AS LOW-LEVEL INSTABILITY RAMPS UP
UNDER MARCH SUNSHINE AND COOLER AIR ALOFT BEGINS TO ENCROACH FROM
THE WEST. ISOLATED SHOWERS WERE CARRIED INTO EARLY EVENING THEN
DIMINISHED WITH LOSS OF HEATING. ANOTHER SHORT-WAVE ROUNDS THE BASE
OF THE LARGE CIRCULATION TONIGHT BRINGING ENHANCED LOWER AND MID
LEVEL MOISTURE...LIFT HOWEVER IN THE PREDOMINANT WESTERLY COLUMN
WIND FLOW APPEARS WEAK TO NON-EXISTENT AND WILL NOT CARRY SHOWERS
AFTER EARLY EVENING TONIGHT.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...UPPER LOW AND THE ASSOCIATED SURFACE
REFLECTION WILL SHIFT EAST THROUGH THE PERIOD BUT ONLY AT A SNAILS
PACE. WITH WEST TO NORTHWEST SURFACE FLOW EXPECTED THROUGH THE
PERIOD...SHOULD SEE TEMPERATURES FALL BACK TO NUMBERS AT OR BELOW
CLIMATOLOGICAL NORMALS. LOWER LEVELS SHOULD BE SUFFICIENTLY DRY
THAT SHOWERS ARE UNLIKELY TO OCCUR DURING THE PERIOD BUT MID AND
UPPER LEVEL MOISTURE ROTATING AROUND THE UPPER LOW WILL LIKELY
RESULT IN VARIABLE SKY CONDITIONS THROUGH THE PERIOD.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 3 AM SATURDAY...SLOW MOVING STORM SYSTEM OFF THE MID ATLANTIC
COAST WILL KEEP N TO NW SURFACE FLOW...PARTLY CLOUDY SKIES...AND
TEMPERATURES AT OR BELOW CLIMATOLOGICAL VALUES THROUGH THURSDAY.
INCREASING SOUTHERLY FLOW IN ADVANCE OF ANOTHER STORM SYSTEM
APPROACHING FROM THE MISSISSIPPI VALLEY FRIDAY WILL RESULT IN WARMER
TEMPERATURES AND MORE SUN FOR FRIDAY. NO POPS THROUGH THE PERIOD
WITH THE ACKNOWLEDGMENT THAT A STRAY SHOWER IS POSSIBLE ALONG THE
COAST THROUGH THE PERIOD.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 12Z...MODERATE CONFIDENCE FORECAST TODAY AS COMPLEX PATTERN
CONTINUES. CURRENT 11U-3.9U SATELLITE IMAGERY SHOWS BACK EDGE OF MID
LEVEL CLOUDS RAPIDLY EXITING TO THE NORTHEAST...AND THE ENTIRE AREA
SHOULD BE DEVOID OF THESE IN THE NEXT HOUR. THIS CLEARING HAS
PERMITTED ENOUGH RADIATIONAL COOLING TO CONDENSE SURFACE MOISTURE
INTO MVFR/IFR STRATUS AND FOG...BUT MOST OF THIS WILL ERODE QUICKLY
AFTER SUNRISE AS GRADIENT WINDS WILL INCREASE RAPIDLY THIS MORNING.
ONCE STRATUS AND FOG DISSIPATES...VFR WILL DOMINATE THROUGH THE REST
OF THE DAY.
NOT EXACTLY A PERFECT DAY ON TAP HOWEVER...EVEN WITH VFR THE RULE.
LARGE U/L LOW AND COLD POOL WILL DRIFT OVERHEAD STEEPENING LAPSE
RATES THROUGH THE EVE. BUFR SOUNDINGS SHOW A PRETTY UNSTABLE
SOUNDING THIS AFTN AT ALL TERMINALS SO SCATTERED CONVECTIVE SHOWERS
ARE LIKELY EVERYWHERE...AND HAVE VCSH IN ALL TAFS. NOT CONCERNED
WITH THUNDER THROUGH AS A WEAK MID LEVEL CAP SHOULD INHIBIT ANY TS.
SOME TEMPO VSBY RESTRICTIONS ARE POSSIBLE IN ANY SHOWERS...BUT HARD
TO PINPOINT AT THIS TIME SO WILL UPDATE AS NECESSARY THIS AFTN. ALL
CONVECTIVE ACTIVITY SHOULD SUBSIDE AFTER SUNSET AS THE ATMOSPHERE
STABILIZES. OTHER CONCERN TODAY WILL BE STRONG W/SW WINDS UNDER A
DEEP M/L. EXPECT GUSTS AT 20 TO 25 KT DEVELOPING EVERYWHERE A FEW
HOURS AFTER SUNRISE...AND CONTINUING THROUGH EARLY TONIGHT.
EXTENDED OUTLOOK...LOW CONFIDENCE IN MVFR WITH SHOWERS SUNDAY. LIGHT
FOG POSSIBLE BOTH MONDAY AND TUESDAY MORNING. VFR WEDNESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 300 PM WEDNESDAY...A BUMPY CHALLENGING OCEAN STATE CURRENTLY
WITH SMALL CRAFT ADVISORY FLAGS AND CAUTIONARY STATEMENTS IN PLACE.
OFFSHORE FORMIDABLE SWELL WAVES MOVING IN FROM THE SOUTHEAST ARE
CLASHING WITH MODERATE WEST-SOUTHWEST SURFACE CHOP THIS MORNING.
SIGNIFICANT WAVE HEIGHTS RANGED FROM 4 TO 6 FEET NORTH OF THE FRYING
PAN SHOALS...TO 3 TO 6 FEET SOUTH OF THE SHOALS AND HIGHEST OFFSHORE.
ITS NOT EXPECTED TO GET MUCH PRETTIER TODAY...AS WSW WINDS MOUNT.
SHORT CRESTED WAVES WILL BUILD OFFSHORE WHILE RESIDUAL SHOREWARD
DIRECTED SWELL WAVES KEEP WAVE HEIGHTS UP. FOR THIS REASON COUPLED
WITH WEST WIND GUSTS IN EXCESS OF 25 KNOTS...ADVISORY FLAGS REMAIN
HOISTED. THERE MAY BE BREAKS IN ADVISORY CONDITIONS FROM TIME TO
TIME...BUT THE HAZARD LEVEL WILL REMAIN ELEVATED DUE TO CONFLICTING
WAVE ENERGY TRAJECTORIES AND ERRATIC WIND GUSTS THROUGH EARLY
SUNDAY.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...SLOW MOVING SURFACE LOW OFF THE COAST WILL
KEEP SOMEWHAT FRISKY W TO NW FLOW GOING THROUGH THE PERIOD. SPEEDS
ARE EXPECTED TO RUN 15 TO 20 KT SUNDAY AND CLOSER TO BUT ABOVE 15 KT
MONDAY. THIS SHOULD ALLOW FOR SEAS TO SUBSIDE BELOW SCA LEVELS OF 6
FEET DURING SUNDAY WITH 3 TO 5 FOOTERS EXPECTED SUNDAY NIGHT THROUGH
MONDAY NIGHT.
LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3 AM SATURDAY...EXPECT CONTINUING WEAKENING OF THE GRADIENT
THROUGH THE PERIOD WITH N WINDS EXPECTED TO RUN 15 KT OR SO. SEAS
SHOULD CONTINUE TO SLOWLY DIMINISH AND SHOULD BE 4 FT OR LESS
THROUGH THE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR AMZ254-256.
SMALL CRAFT ADVISORY UNTIL NOON EDT SUNDAY FOR AMZ250-252.
&&
$$
NEAR TERM...COLBY
SHORT TERM...XXXI
LONG TERM...XXXI
AVIATION...WEISS
NWS ILMNWS Office Area Forecast Discussion