Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 220929 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 429 AM EST SAT NOV 22 2014 .SYNOPSIS... CLOUDS WILL SLOWLY INCREASE TODAY WITH TEMPERATURES REMAINING COOL. A DEVELOPING STORM SYSTEM BREWING IN THE GULF OF MEXICO WILL LIFT NORTHEAST BRINGING MUCH MILDER TEMPERATURES SUNDAY AND MONDAY...ALONG WITH UNSETTLED AND WET WEATHER. ANOTHER SYSTEM WILL BRING ANOTHER ROUND OF RAIN BY MIDWEEK WITH CONDITIONS DRYING OUT BY THE END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 330 AM SATURDAY...LONGWAVE UPPER PATTERN THIS PERIOD IS CURRENTLY EITHER IN A TRANSITION TO A NEW PATTERN OR JUST TEMPORARILY RE-CONFIGURING ITSELF BACK TO THE LONGWAVE UPPER TROF PATTERN THAT AFFECTS THE EASTERN 1/3RD TO 2/3RDS OF THE U.S. FOR THE NEAR TERM PERIOD...ZONAL FLOW ALOFT TO BUCKLE. THIS A RESULT OF A SOUTHERN STREAM S/W UPPER TROF THAT PUSHES FROM THE DESERT SW U.S. TO THE WESTERN GULF OF MEXICO BY SUNDAY DAYBREAK. A S/W LOW AMPLITUDE UPPER RIDGE WILL AFFECT THE FA THIS PERIOD. NAM BUFR SOUNDINGS AND VARIOUS MODEL TIME HEIGHT DISPLAYS ACROSS THE FA...ILLUSTRATE A RATHER DRY ATM COLUMN TODAY THRU THE 1ST HALF OF TONIGHT. THIS EVIDENCED BY PWS LESS THAN ONE-QUARTER OF AN INCH. THIS WILL RESULT IN MAINLY CLEAR SKY CONDITIONS TODAY INTO THIS EVENING. LOW LEVEL FLOW THIS AFTERNOON AND TONIGHT COULD DRIVE A PORTION OF THE OFFSHORE STRATO-CU DECK ONSHORE...MAINLY ACROSS THE ILM SC CWA. DURING THE PRE-DAWN SUNDAY HRS...WITH THE S/W UPPER TROF REACHING THE GULF OF MEXICO...FLOW AHEAD OF THIS FEATURE WILL TAP BOTH GULF OF MEXICO AND ATLANTIC OCEAN MOISTURE SOURCES. AND AS A RESULT...LOOK FOR AN INCREASE IN CLOUDINESS AND POPS TOWARD DAYBREAK SUN...FROM SW TO NE. STRATIFORM ISENTROPIC TYPE LIGHT PCPN WILL PRIMARILY BEGIN TO AFFECT THE FA EARLY SUN MORNING. MODELS HINT OF A COASTAL TROF DEVELOPING ALONG THE PERIPHERY BETWEEN THE COASTAL AND OFFSHORE WATERS. THIS BASICALLY TO BECOME AN EXTENSION TO THE WARM FRONT ASSOCIATED WITH THE MAIN LOW DEVELOPING OVER THE SOUTH CENTRAL U.S. VARIOUS MODEL MOS GUIDANCE SIMILAR TO TODAYS MAXES BUT DIVERGE- SOME CONCERNING TONIGHTS LOWS. COULD SEE TONIGHTS MINS OCCURRING AROUND MIDNIGHT BEFORE EITHER HOLDING STEADY OR SLOWLY RISING FOR THE REMAINDER OF TONIGHT. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... AS OF 330 AM SATURDAY...POTENT STORM SYSTEM...NOW SEEN ON IR SATELLITE IMAGERY MOVING ACROSS TEXAS WILL BRING A SIGNIFICANT RAIN EVENT TO THE AREA SUNDAY. THIS SYSTEM WILL MOVE UP INTO THE MISSISSIPPI VALLEY AND SHEAR OUT BUT COPIOUS MOISTURE NOW SEEN POOLING IN THE GULF OF MEXICO WILL BE DRAWN NORTHWARD IN A ORGANIZED FASHION. A LITANY OF FORCING MECHANISMS WILL BE WORKING IN TANDEM INCLUDING A DIFFUSE WARM FRONT AND SPEED CONVERGENCE FOR THE LOWER LEVELS AND MID AND UPPER LEVEL DIFLUENCE. LONG STORY SHORT...I HAVE ELEVATED POPS TO 100 ACROSS THE BOARD FOR LATE SUNDAY MORNING THROUGH THE EVENING HOURS. THE NAM IS A LITTLE FASTER MOVING THE SYSTEM THROUGH BUT OPTED FOR THE GFS SOLUTION CITING THE CONSISTENCY. SEVERE THREAT PARAMETERS REMAIN UNCHANGED...A LOT OF SHEAR AND LOW LEVEL HELICITY BUT THE INSTABILITY REMAINS IN QUESTION. SPC HAS NOW MOVED ALL AREAS OF THE CWA INTO A SLIGHT RISK WITH THE DAY TWO OUTLOOK. TEMPERATURE FORECAST REMAINS IN PLACE MOST NOTABLY THE EXPECTATION OF UPPER 70S MONDAY COURTESY OF THE STRONG SOUTHWEST FLOW THAT REMAINS IN PLAY...THIS DESPITE OVERCAST SKIES WITH LOWER CEILINGS. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 330 AM SATURDAY...MEDIUM RANGE GUIDANCE IS NOW COMING INTO BETTER AGREEMENT AT LEAST FOR THE FIRST COUPLE DAYS OF THE EXTENDED. A SECONDARY DEEP AND PROGRESSIVE SHORTWAVE DIVING INTO THE LOWER MISSISSIPPI VALLEY ONCE ACTS ON ABUNDANT MOISTURE FROM THE GULF OF MEXICO PAINTING ANOTHER WET SCENARIO FOR LATE TUESDAY AND WEDNESDAY. THE GUIDANCE HAS BEEN OFF AND ON THE PAST FEW DAYS WITH THIS SCENARIO BUT WITH BOTH THE GFS AND 0000 UTC ECMWF DEVELOPING RAIN WELL INLAND...CONFIDENCE IS HIGHER. THE PRIMARY FORCING WILL BE THE RIGHT ENTRANCE REGION OF THE 200-300 JET MOVING SLOWLY SOUTH TO NORTH ALONG THE COAST. I HAVE INCREASED POPS TO LIKELY FOR WEDNESDAY BUT SUBSEQUENT SHIFTS MAY WANT TO INCREASE TO CATEGORICAL IN SHORT ORDER. BEYOND THIS...A LITTLE BETTER AGREEMENT AS WELL WITH A BROAD TROUGH ENVELOPING THE EASTERN THIRD OF THE U.S WITH HIGH PRESSURE AT THE SURFACE. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/... AS OF 06Z...HIGH CONFIDENCE FOR VFR THRUOUT THE VALID ISSUANCE PERIOD. THE ELONGATED CENTER OF 1030+ MB HIGH PRESSURE WILL LIE NEARLY OVERHEAD TODAY...WITH CONTINUED SUBSIDENCE AFFECTING THE LOCAL TERMINALS. VARIOUS MODEL SOUNDINGS FOR LOCAL TERMINALS INDICATE A VERY DRY AIRMASS TO AFFECT THE FA...WITH PWS LESS THAN ONE-QUARTER OF AN INCH. BY LATE TODAY THRU TONIGHT...LOW LEVEL WINDS VEER WITH HEIGHT. THE SC FIELD JUST OFFSHORE...MAY GET DRAWN ACROSS THE COASTAL TERMINALS LATER TONIGHT JUST BEYOND THE 06Z ISSUANCE PERIOD. OTHERWISE...LOOKING AT SKC CONDITIONS. WINDS GENERALLY BELOW 10 KT THRUOUT THE 06Z PERIOD...AND MAY BECOME VARIABLE IN DIRECTION AT LESS THAN 3 KT DUE TO THE CENTER OF HIGH PRESSURE OVERHEAD. EXTENDED OUTLOOK...MVFR/IFR CIGS AND VSBY BY SUNDAY AFTERNOON AND CONTINUING THRU SUNDAY NIGHT. THIS DUE TO STRATIFORM RAINS AHEAD OF A WARM FRONT BECOMING CONVECTIVE IN NATURE AFTER THE WFP SUNDAY NIGHT INTO MON. FOR TUESDAY VFR INLAND TERMINALS WITH MVFR/-RA COASTAL TERMINALS. FOR WEDNESDAY MVFR/-RA EARLY WITH VFR THRUOUT LATER IN THE DAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 345 AM SATURDAY...ELONGATED CENTER OF 1030+ MB HIGH PRESSURE...PROGGED TO PUSH EAST ACROSS THE LOCAL WATERS TODAY...AND OFFSHORE TONIGHT. WITH SUCH A COMPACT HIGH... THE SFC PG QUICKLY TIGHTENS ACROSS THE LOCAL WATERS AS THE CENTER PULLS AWAY. LOOKING AT NE-ENE WINDS AT 10 TO 15 KT TODAY ...WITH A MORE SOLID 15 KT ACROSS THE ILM SC WATERS. FOR TONIGHT...ON THE BACKSIDE OF THE OFFSHORE MOVING HIGH...WINDS WILL SLIGHTLY VEER TO THE ENE TO ESE WITH A SLIGHT INCREASE IN SPEEDS DURING THE PRE-DAWN SUN HOURS. STRATIFORM TYPE PCPN WILL BEGIN OVERSPREADING THE LOCAL ILM SC WATERS TOWARD DAYBREAK SUN. SIGNIFICANT SEAS WILL RANGE BETWEEN 2 AND 4 FT THRU TONIGHT...AND BEGIN TO FURTHER BUILD BY DAYBREAK SUN IN RESPONSE TO INCREASING ONSHORE TYPE WINDS. AVERAGE PERIODS WILL RANGE BETWEEN 4.5 TO 5.0 SECONDS. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 330 AM SATURDAY...BASED ON MODEL CONSISTENCY...WILL RAISE A SMALL CRAFT ADVISORY FOR ALL WATERS BEGINNING SUNDAY MORNING AND CONTINUING THROUGH TUESDAY AM. THIS AS A POTENT STORM SYSTEM AFFECTS THE SOUTHEAST. WINDS WILL QUICKLY RAMP UP FROM THE SOUTHEAST TO 20-25 KNOTS AND EVEN A LITTLE HIGHER SUNDAY AFTERNOON FOR A BRIEF PERIOD. WARM AIR ADVECTION AND LIMITED CONVECTIVE MIXING PROBABLY KEEPS A GALE WARNING OUT OF PLAY AS THE WINDS OFF THE DECK ARE QUITE STRONG. THIS WILL QUICKLY BUILD SEAS TO 5-8 FEET. THE WINDS WILL DIMINISH SLIGHTLY FOR MONDAY AND VEER TO THE SOUTHWEST BUT REMAIN SUFFICIENTLY STRONG...AROUND 20 KNOTS TO KEEP SEAS WORKED UP. A WEAKER WESTERLY FLOW SHOULD FINALLY GIVE MARINERS A BRIEF BREAK BEGINNING TUESDAY. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 330 AM SATURDAY...RELATIVELY LIGHT WIND FIELDS TUESDAY AS WEAK HIGH PRESSURE BUILDS IN BRIEFLY. BY WEDNESDAY AN ELONGATED LOW DEVELOPS AND MOVES WELL OFFSHORE BUT IS ENOUGH TO GIVE MORE CONSISTENCY TO THE WIND DIRECTION...NORTH...NORTHEAST. SPEEDS WILL INCREASE TO 20-25 KNOTS AS WELL. SEAS WILL DIP TO A RANGE OF 2-4 FEET TUESDAY AND BUILD ONCE AGAIN WITH THE INCREASE IN WINDS WEDNESDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 10 AM SUNDAY TO 7 AM EST TUESDAY FOR AMZ250-252-254-256. && $$ SYNOPSIS...SHK NEAR TERM...DCH SHORT TERM...SHK LONG TERM...SHK AVIATION...DCH/MAC

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