000 FXUS62 KILM 100522 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1222 AM EST FRI FEB 10 2012 .SYNOPSIS... HIGH PRESSURE OVER THE MID-MISSISSIPPI RIVER VALLEY WILL BUILD EAST INTO THE CAROLINAS THROUGH FRIDAY. A STRONG COLD FRONT WILL PUSH ACROSS THE REGION ON SATURDAY...FOLLOWED BY VERY COLD AND DRY AIR-MASS ON SUNDAY. THE CENTER OF THE HIGH PRESSURE WILL MOVE ACROSS THE REGION MONDAY. ANOTHER STORM SYSTEM MAY IMPACT THE AREA TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1230 AM FRIDAY...WE'RE IN A MAINLY CLEAR HOLE IN THE CIRRUS CANOPY THAT BLANKETS MUCH OF THE SOUTHEASTERN U.S. AND THE OFFSHORE WATERS. THIS HAS ALLOWED GOOD RADIATIONAL COOLING TO DROP TEMPERATURES INTO THE LOWER-MID 30S IN MOST SPOTS...WITH SOME UPPER 20S ALREADY OBSERVED IN NORMAL COLD SPOTS ACROSS SOUTHEAST NC'S POCOSIN SWAMPLANDS. GOOD RADIATIONAL COOLING SHOULD CONTINUE FOR ANOTHER ~3 HOURS WITH MAINLY CLEAR SKIES...AT WHICH POINT INCREASING CIRRUS CLOUD COVER SHOULD FORCE A STEADY TO SLIGHTLY RISING TEMPERATURE CURVE OVERNIGHT WITH WEAK WARM ADVECTION ALREADY ONGOING ABOVE THE SURFACE. PREVIOUS DISCUSSION FROM 9 PM FOLLOWS... THIN TO OCCASIONALLY OPAQUE CIRRUS CONTINUES TO MOVE ACROSS THE FORECAST AREA THIS EVE. THESE CLOUDS ARE ASSOCIATED WITH AN UPPER LEVEL JET STREAK STREAMING ALONG THE GULF COAST OUT OF A TROUGH EXTENDING SW OUT OF TX INTO MEXICO ATOP A MID LEVEL CUTOFF LOW THAT WILL FURTHER DISCONNECT FROM THE FLOW AND SINK SOUTHWARD. AS THIS OCCURS THERE WILL BE A SLIGHT STRENGTHENING AND VERTICAL DEEPENING OF THE UPPER LEVEL JET STREAK WHICH SHOULD MORE READILY IMPORT THIS MOISTURE ACROSS THE CAROLINAS. THIS APPEARS TO HAPPEN WITH THE MOST VIGOR AFTER ABOUT 06Z. TEMPS HAVE BEEN ADJUSTED DOWNWARD IN THE NEAR TERM TO ACCOUNT FOR NEAR TERM TRENDS. THE HIGH CLOUDS SHOULD HELP TO KEEP TEMPS A DEG OR TWO HIGHER THAN IF SKIES WERE CLEAR ALL NIGHT LONG. HOWEVER...MINIMUMS WERE ADJUSTED DOWNWARD ACROSS THE BOARD WITH LOWS COMMONLY IN THE UPPER 20S AND LOWER 30S...WITH PERHAPS A FEW MID 20S WHERE RADIATIONAL COOLING IS ABLE TO MAXIMIZE. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 PM THURSDAY...HIGH PRESSURE AT THE SURFACE WILL GIVE WAY TO THE BEST COLD AIR SINCE THE BEGINNING OF THE YEAR. THE NUMERICAL GUIDANCE CONTINUES TO SHOW THE UPPER LEVEL PATTERN WITH TWO SHORTWAVE TROUGHS ROTATING AROUND THE LOW OVER NORTH QUEBEC. THE FIRST SHORTWAVE INCREASES THE SOUTHERLY FLOW AND ISENTROPIC LIFT ON THE 295 KELVIN SURFACE. THIS WILL PROVIDE THE LIFT BY FRIDAY AFTERNOON TO INCREASE CLOUDS AND THEN BY FRIDAY NIGHT THE MAXIMUM VERTICAL MOTION AHEAD OF THE FIRST SHORT WAVE TROUGH WILL PROVIDE FOR THE BEST CHANCES OF PRECIPITATION. AT THIS TIME WHILE THE PROBABILITIES OF PRECIPITATION HAVE INCREASE TO LIKELY IN THE NORTHEAST PORTION OF THE COUNTY WARNING AREA BUT THE QPF VALUES ARE NOT EXPECTED TO RUN MORE THAN QUARTER OF AN INCH ALONG THE SOUTHEAST NORTH CAROLINA COAST AND LESS AMOUNTS TO THE SOUTHWEST. TEMPERATURE FORECAST ARE RUNNING A COUPLE OF DEGREES BELOW YESTERDAY FORECAST WITH HIGHS EXPECTED TO REACH NEAR 60 BOTH FRIDAY AND SATURDAY. LOWS WILL RUN IN THE LOWER TO MID 40S FRIDAY NIGHT BUT WITH THE STRONG COLD AIR ADVECTION EXPECTED BEHIND THE COLD FRONT AND ASSOCIATED WITH THE SECOND SHORT WAVE SATURDAY NIGHT...LOWS ARE EXPECTED TO REACH INTO THE UPPER 20. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 3 PM THURSDAY...VERY COLD TO BEGIN THE PERIOD WITH DEEP 500MB LONGWAVE TROUGHING ACROSS THE EAST. 500MB HEIGHTS DROP BELOW 550DM WHILE 850MB TEMPS FALL TO -8C...BOTH REPRESENTING A NEGATIVE DEPARTURE OF NEARLY 2 STANDARD DEVIATIONS FROM NORMAL. SO EVEN WITH FULL SUNSHINE...MAX TEMPS SUNDAY WILL STRUGGLE INTO THE MID 40S...NEARLY 15 DEGREES BELOW CLIMO...WHICH WHEN COMBINED WITH NW WIND WILL MAKE IT FEEL LIKE LESS THAN 40 ALL DAY. AS HIGH PRESSURE MOVES OVERHEAD SUNDAY NIGHT...NEARLY IDEAL RADIATIONAL COOLING WILL OCCUR ALLOWING TEMPS TO PLUMMET TO THE LOWER 20S...AROUND 20 IN THE TRADITIONAL COLDEST SPOTS. DEEPENING SOUTHERN STREAM SHORTWAVE TROUGH BEGINS TO TAKE SHAPE ACROSS THE SOUTHERN PLAINS MONDAY...WITH DOWNSTREAM RESPONSE SHORTWAVE RIDGING DEVELOPING ACROSS THE SOUTHEAST. AT THE SAME TIME...SURFACE HIGH PRESSURE BEGINS TO DRIFT OFFSHORE BUT ANY STRONG WAA WILL HOLD OFF ONE MORE DAY LEADING TO A WARMER...BUT STILL BELOW NORMAL...DAY ON MONDAY...BEFORE TEMPS RISE ONCE AGAIN TO SEASONABLE LEVELS FOR MID WEEK. GUIDANCE IN DECENT AGREEMENT NOW WITH THE PLAINS SHORTWAVE MOVING RAPIDLY ACROSS THE COUNTRY...WITH ITS ASSOCIATED SURFACE REFLECTION TRACKING ALONG THE SOUTHERN STATES. SPLIT FLOW PATTERN DOES NOT FAVOR ANY SIGNIFICANT STRENGTHENING OF THIS FEATURE...BUT WILL INCREASE POP TO CHANCE ACROSS THE AREA TUE AND TUE NIGHT. WARM AIR FLOODS INTO THE AREA AHEAD OF THIS SYSTEM...CAUSING 850MB TEMPS TO RISE ABOVE 0C AND 1000-850MB THICKNESSES TO SWELL BEYOND 1320M...SO EVEN AT ONSET ALL PRECIP SHOULD BE IN LIQUID AND ATTM AM NOT CONCERNED ABOUT ANY FALLING OF THE FROZEN VARIETY. COLD FRONT PUSHES THROUGH WEDNESDAY...BUT LIMITED COLD AIR BEHIND IT MEANS TEMPS WILL NOT CHANGE MUCH...AND WILL PERSIST AROUND CLIMO THROUGH THURSDAY. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AS OF 06Z...THROUGH SUNRISE WINDS WILL BE NEARLY CALM. THICKEST CIRRUS IS OFFSHORE...BUT MORE IS POISED TO MOVE BACK INTO THE TERMINALS BY SUNRISE. SOME SC CLOUDS ARE NOTED NEAR A SUBSIDENCE INVERSION AT 4K WELL SOUTH OF THE TERMINALS. SOME OF THESE CLOUDS COULD SCOOT NORTHEAST TOWARDS THE MYR/CRE TERMINALS BY SUNRISE. THE CHANCE OF DENSE FOG DEVELOPMENT REMAINS LOW BUT CANNOT RULE OUT A TEMPO MVFR VISIBILITY IN THE PRE-DAWN HOURS UNTIL SUNRISE...ESPECIALLY AT LBT/FLO/CRE. AFTER 12Z SOUTHEAST WINDS WILL DEVELOP AFTER THE INVERSION BREAKS 14-15Z. INCREASING MOISTURE WILL RESULT IN LOW VFR LEVEL CEILINGS SPREADING SOUTH TO NORTH ACROSS THE TERMINALS DURING MORNING AND AFTERNOON. LIGHT RAIN WILL BEGIN AT THE SOUTHERN TERMINALS DURING THE AFTERNOON SPREADING TO THE NORTHERN TERMINALS BY LATE AFTERNOON. THERE IS MODERATE TO HIGH CONFIDENCE THAT MVFR CONDITIONS WILL DEVELOP AT ALL TERMINALS EXCEPT ILM MID-LATE AFTERNOON. THERE IS MODERATE CONFIDENCE OF IFR/MODERATE RAIN AT THE FLO TERMINAL TOWARDS THE END OF THIS TAF VALID PERIOD. THE REMAINING TERMINALS WILL LIKELY DETERIORATE TO IFR 00-03Z. A FRONT WILL MOVE THROUGH DURING THE EVENING BUT IFR CONDITIONS WILL LIKELY CONTINUE. EXTENDED OUTLOOK...VFR DEVELOPING SATURDAY. LOW CONFIDENCE FOG MONDAY MORNING. MODERATE CONFIDENCE IFR/RAIN TUESDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1230 AM FRIDAY...NO SIGNIFICANT CHANGES TO WINDS OR SEAS WITH THIS EARLY MORNING NEAR-TERM UPDATE. I DID MAKE SUBSTANTIAL CHANGES TO HOURLY AIR TEMPERATURE FORECASTS FOR THE NEXT 6-9 HOURS WITH CURRENT READINGS RANGING FROM THE LOWER 50S AT THE FRYING PAN SHOALS BUOY TO THE UPPER 40S AT THE SURF ZONE/PIERS. THIS IS AS MUCH AS A 10 DEGREE UPWARD REVISION TO THE FORECAST IN SPOTS. PREVIOUS DISCUSSION FROM 9 PM FOLLOWS... NE WINDS AT 10 KT OR LESS WILL CONTINUE INTO FRI MORNING WITH HIGH PRESSURE SITUATED ACROSS THE WATERS. LOW WIND SPEEDS WILL YIELD LOW WAVE HEIGHTS...2 FT OR LESS. SOUTH OF THE WATERS...WINDS AND SEAS WILL BE INCREASING AS A DEVELOPING COASTAL TROUGH HELPS TO TIGHTEN THE PRESSURE GRADIENT. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 PM THURSDAY...HIGH PRESSURE WILL CONTINUE OVER THE WATERS ON FRIDAY BEFORE GIVING WAY TO A VERY STRONG COLD FRONT SATURDAY. THE SOUTHERLY WINDS WILL VEER TO THE NORTHWEST BEHIND THE FRONT. WINDS WILL INCREASE TO 15 TO 20 KNOTS WITH SEAS INCREASING TO 4 TO 5 FEET AT 20 MILES OFF THE COAST BEHIND THE FIRST FRONT. A SECOND COLD FRONT WILL PASS THROUGH LATER SATURDAY AND WITH THE COLD AIR ADVECTION PASSING OVER THE WARMER WATERS WINDS SPEED WILL INCREASE TO 25 TO 30 KNOTS AND THE NORTHWEST WINDS WILL CAUSE THE SEAS TO RANGE FROM 2 FEET NEAR SHORE TO 6 FEET AT 20 MILES OFF THE COAST. A STRONG SMALL CRAFT ADVISORY MAINLY FOR STRONG WINDS WILL LIKELY BE NEEDED FOR SATURDAY NIGHT INTO SUNDAY. LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 3 PM THURSDAY...STRONG NW WINDS OF 20-25 KTS BEHIND DEPARTING COLD FRONT WILL EASE THROUGH THE FIRST HALF OF SUNDAY. WHAT WILL LIKELY BE AN ONGOING SCA WILL CONTINUE DURING THIS TIME...BEFORE BEING DROPPED SUNDAY AFTN AS WINDS AND SEAS EASE. WINDS FALL TO 10-15 KTS BY SUNDAY NIGHT...AND SEAS DROP RAPIDLY TO ONLY 2-3 FT AS NW WINDS PUSH THE HIGHEST SEAS WELL OFFSHORE. HIGH PRESSURE THEN BUILDS OVERHEAD PRODUCING A VERY WEAK PRESSURE GRADIENT AND LIGHT/VARIABLE WINDS OF LESS THAN 10 KTS THROUGH TUESDAY MORNING. AT THAT POINT...HIGH DRIFTS FURTHER OFFSHORE ALLOWING FOR INCREASING SW RETURN FLOW OF AROUND 15 KTS THROUGH THE END OF THE PERIOD. SEAS MONDAY HOVER ONLY AROUND 1 FT...BEFORE BUILDING BACK UP TO 3-5 FT TUESDAY AFTN IN RESPONSE TO THE INCREASING SW WINDS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...TRA SHORT TERM...DRH LONG TERM...JDW AVIATION...MRR