000 FXUS62 KILM 100528 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1228 AM EST WED MAR 10 2010 .SYNOPSIS... HIGH PRESSURE WILL REMAIN IN CONTROL OF THE WEATHER THROUGH EARLY WEDNESDAY. A SLOW MOVING STORM SYSTEM APPROACHING FROM THE CENTRAL UNITED STATES WILL AFFECT THE AREA FROM LATE WEDNESDAY INTO THE UPCOMING WEEKEND. ACCOMPANYING THE STORM SYSTEM WILL BE INCREASING CHANCES FOR RAIN WEDNESDAY NIGHT THROUGH FRIDAY. DRY WEATHER IS EXPECTED TO RETURN FOR THE LATTER HALF OF THE WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... AS OF 900 PM TUESDAY...SOMEWHAT FLATTENED UPPER RIDGE TO AFFECT THE AREA OVERNIGHT...WITH THE RIDGE AXIS PROGGED TO MOVE EAST TO JUST OFF THE SE U.S. COAST BY DAYBREAK WEDNESDAY. THE 1ST UPPER CLOSED LOW AND ITS ACCOMPANYING SFC LOW MOVE NNE WITHIN THE PLAINS STATES OVERNIGHT. THE ATM COLUMN IS PROGGED TO MOISTEN UP SOME...ESPECIALLY SW PORTIONS OF THE ILM CWA WITH GULF MOISTURE BECOMING MORE AVAILABLE...AS WELL AS LOW LEVEL SOUTHERLY RETURN FLOW AROUND THE SFC HIGH. DECENT SWATH OF UVVS TO DEVELOP AND/OR REACH THE SW PORTIONS BY DAYBREAK WED IN RESPONSE TO THE FORECAST AREA WITHIN THE LEFT FRONT QUADRANT OF A 300 MB JET LOCATED FROM SOUTHERN TEXAS TO FLORIDA. ENOUGH MOISTURE WILL RESIDE IN THE ATM TO BE CONDUCIVE FOR PCPN DEVELOPMENT BY DAYBREAK WEDNESDAY ESPECIALLY ACROSS THE SW PORTIONS...AND SPREADING NEWARD DURING THE DAY. AS FOR PCPN AMOUNTS...ONLY TALKING LESS THAN ONE TENTH OF AN INCH INTO WED EVENING. WILL LIKELY HAVE TO INCREASE OVERNIGHT POPS AND CLOUD COVER...AS WELL AS MIN TEMPS. INSULATING EFFECTS FROM THE CLOUDS AND POSSIBLE LATE NIGHT PCPN WILL KEEP MIN TEMPS UP...RATHER THEN ANY WAA. AFTN/EVENG SEA BREEZE HAS PUSHED DEWPOINTS UPWARDS AND DONT EXPECT THEM TO RECOVER WITH THE OVERALL SYNOPTIC PATTERN OF INCREASING DEWPOINTS TO OCCUR OVERNIGHT INTO WEDNESDAY. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... AS OF 3 PM TUESDAY...FORECAST AREA WILL REMAIN BETWEEN HIGH PRESSURE OFF THE EAST COAST AND LARGE STORM SYSTEM OVER THE MIDWEST. DEEP SOUTH TO SOUTHWEST FLOW WILL ADVECT GULF AND ATLANTIC MOISTURE INTO THE SOUTHEASTERN US. INCREASING MID LEVEL MOISTURE WED RESULTS IN ABUNDANT CLOUD COVER...BUT DRY LOW LEVELS AND LIMITED INSTABILITY WILL KEEP POPS LOW. WEAK WARM ADVECTION WILL PUSH HIGHS INTO THE UPPER 60S/LOWER 70S DESPITE CLOUD COVER. PRECIP CHANCES INCREASE WED NIGHT AS LOWER LEVELS BECOME SATURATED AND FLOW ALOFT BECOMES DIVERGENT. CLOUDS AND SOUTHERLY FLOW WILL KEEP LOWS 50S. HIGHEST POPS THU AS PASSING SHORTWAVE ENHANCES LIMITED SURFACE BASED INSTABILITY. THOUGH CAPE IS LOW CANNOT RULE OUT A FEW THUNDERSTORMS. WARM ADVECTION CONTINUES ON THU BUT PRECIP AND INCREASED CLOUD COVER WILL KEEP HIGHS A LITTLE CLOSER TO CLIMO. LINGERING CLOUDS THU NIGHT KEEP LOWS IN THE LOW TO MID 50S. MAY HAVE SOME LIGHT SHOWERS THU NIGHT BUT DRY AIR ALOFT AND MID LEVEL STABILITY WILL KEEP COVERAGE MINIMAL. && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 3 PM TUESDAY...BY FIRST LIGHT OF FRIDAY A SLUGGISHLY MOVING UPPER LOW WILL BE POSITIONED OVER THE MIDDLE MISSISSIPPI VALLEY WITH DEEP SOUTHERLY FLOW ALREADY ENTRENCHED ACROSS THE EASTERN CAROLINAS. SEVERAL IN A SERIES OF IMPULSES ALOFT WILL TRACK FROM SOUTHWEST TO NORTHEAST AHEAD OF THIS LARGE SCALE CYCLONE IN THE PERIOD FRIDAY THROUGH SUNDAY...PRODUCING PERIODS OF SHOWERS. QPF WISE THE BEST RAIN POTENTIAL ARRIVES FRIDAY NIGHT INTO EARLY SATURDAY MORNING AS ONE OF THE STRONGER IMPULSE TRACKS OVERHEAD. FOLLOWING THIS FEATURE COLUMN WIND FLOW WILL SHIFT TO THE WEST AS BOTH THE UPPER LOW AND ITS ATTENDANT SURFACE LOW PULL NORTH OF THE FORECAST AREA. THIS WILL SHARPLY DECREASE RAINFALL POTENTIAL...BUT LIGHTER SHOWERS WILL LIKELY LINGER THROUGH SATURDAY AS THE SOUTHERN EXTENT OF A COOL POOL ALOFT AND MARCH INSOLATION INTERACT. WILL KEEP MENTION OF PCPN THROUGH SATURDAY EVENING AS THE LAST STRONG LOBE OF VORTICITY PASSES OVER THE FORECAST AREA ROUNDING THE BASE OF THE EXITING UPPER LOW. EXPECT ABOVE NORMAL TEMPERATURES IN BLUSTERY SOUTHERLY FLOW FRIDAY INTO EARLY SATURDAY...FOLLOWED BY NEAR NORMAL TEMPERATURES FOR MID MARCH SUNDAY THROUGH TUESDAY AS COOLER AIR FILTERS INTO THE REGION. BEYOND TUESDAY A BAG OF MIXED SIGNALS IN THE MODELS...TYPICAL OF A SPRING TRANSITION...HINT THAT WINTER IS NOT COMPLETELY OVER WITH. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... INCREASING MID CLOUDS ARE EXPECTED OVER THE NEXT SIX HOURS AS MOISTURE INCREASES STEADILY FROM THE WEST WELL IN ADVANCE OF A LARGE LOW PRESSURE SYSTEM. LIGHT SOUTHWEST SURFACE WINDS ARE EXPECTED AND WINDS WITHIN THE BOUNDARY LAYER WILL BE HIGH ENOUGH THAT NO FOG IS EXPECTED. LOOK FOR SHOWERS POSSIBLE BY LATE AFTERNOON OR THIS EVENING AS SOME WEAK ISENTROPIC LIFT BEGINS. CONDITIONS SHOULD REMAIN VFR THROUGH 00Z...WITH A SLIGHT CHANCE OF MVFR CEILINGS IF THE SHOWERS HAPPEN TO BECOME MODERATE. EXTENDED OUTLOOK...MEDIUM CONFIDENCE FOR PERIODS OF IFR/RAIN AND POSSIBLE THUNDERSTORMS AS APPROACHING STORM SYSTEM MOVES INTO THE AREA FOR THURSDAY. CONDITIONS WILL BE UNSETTLED THROUGH SATURDAY MORNING WITH INTERMITTENT LOW CEILINGS AND PRECIP. LOW CONFIDENCE FOR POSSIBLE SHOWERS FOR SUNDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 900 PM TUESDAY...PROGGED SFC PRESSURE PATTERN AND GRADIENT CURRENTLY YIELDING S TO SW WINDS AROUND 10 KT. LATEST MODEL MOS GUIDANCE CONTINUES THESE WINDS OVERNIGHT AND SEE NO REASON TO SWAY FROM THIS OUTPUT. SEAS AROUND 2 FT WILL CONTINUE OVERNIGHT...MAINLY IN AN ESE 10 SECOND PLUS GROUND SWELL. THE STRATIFORM TYPE LIGHT PCPN WILL RESIDE OVER LAND AREAS. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 PM TUESDAY...SOUTHERLY FLOW OVER THE WATERS WED STARTS TO INCREASE DURING THE AFTERNOON AS GRADIENT BEGINS TIGHTENING. SPEEDS WED AND WED NIGHT REMAIN UNDER 15 KT WITH SEAS UNDER 4 FT. SPEEDS REALLY START TO PICK UP THU AS GRADIENT BECOMES PINCHED. FLOW BECOMES A LITTLE MORE ONSHORE WITH SPEEDS NEAR 20 KT THU AFTERNOON. INCREASED ONSHORE FLOW WILL BUILD SEAS THU...LIKELY REQUIRING A HEADLINE IN THE AFTERNOON. STRONG ONSHORE FLOW CONTINUES OVERNIGHT AHEAD OF WEAK WAVE CROSSING SOUTHERN SC. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 3 PM TUESDAY...THE OCEAN WILL BE ROUGHED UP FROM SE FETCH AND SMALL CRAFT ADVISORY FLAGS WILL LIKELY BE RAISED AT DAYBREAK FRIDAY...BUT SHOULD SUBSIDE BELOW 6 FEET BY FRIDAY AFTERNOON OR EARLY EVENING WITH EASING SSE WINDS OFFSHORE. MODERATE WESTERLY WIND FLOW MARKS THE REMAINDER OF THE FORECAST PERIOD WITH DEEP LOW PRESSURE SITUATED NORTH OF THE WATERS...AND HIGH PRESSURE ANCHORED OVER SOUTHERN FLORIDA AND THE BAHAMAS. A SMALL CRAFT ADVISORY FOR STRONG WEST WINDS MAY BE NEEDED SATURDAY NIGHT AS LOW PRESSURE DEEPENS NORTH OF THE AREA. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...TRL NEAR TERM...DCH SHORT TERM...III LONG TERM...MJC AVIATION...TRA
NWS ILMNWS Office Area Forecast Discussion