Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 200947 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 547 AM EDT Tue Mar 20 2018 .SYNOPSIS... Low pressure moving eastward, will affect the Carolinas today. It`s associated cold front will push across the local area tonight as the intensifying low tracks off the NC Coast and then slowly northeastward while continuing to further deepen. Possible strong to severe thunderstorms will occur ahead of the low early this morning and potentially again this afternoon thru early evening. Cold and dry high pressure will finally extend across the Carolinas Thursday and Friday with morning lows flirting with 32 degrees. The weekend into early next week may become unsettled while continuing on the cool side. && .NEAR TERM /THROUGH TONIGHT/... As of 3 AM Tuesday...Line of convection being pushed east this morning by shortwave/low pressure combo is lifting a warm front across the area. Widespread showers with embedded thunderstorms will move off the coast around 12Z. Boundary layer is somewhat stable this morning and low level jet is not very impressive. Instability is also lacking given the nocturnal timing. Cannot rule out an isolated strong wind gust in the predawn hours but severe weather seems unlikely. Warm front pushes north of the area this morning with low level jet of 45 to 55 kt helping spread warm, moist air over the region. Highs today will climb into the mid to upper 70s with potential for low 80s with any peaks of sun. Dewpoints will rise into the low to mid 60s today. Aloft the progressive mid-level pattern becomes more amplified as a shortwave moves into the TN Valley and acquires a negative tilt. Lapse rates steepen from late morning into early afternoon, when CAPE values are forecast to be around 2k J/kg. Low pressure moving into the area this afternoon, along the front, will be gaining strength as it slowly moves east. Low level convergence along the cold front and dynamics associated with the developing low should be enough to generate widespread deep convection. There remains potential for strong to severe storms this afternoon, possibly lingering into the first part of the evening, and SPC continues to carry an enhanced risk for the coastal areas and a marginal for areas just inland from the coast. Second round of convection pushes offshore this evening, ending any severe threat and commencing a period of cold advection. Temps drop below climo by the end of the period with lows in the upper 30s to lower 40s possible. Although precip chances rapidly decrease this evening and overnight, moisture from 2-4k ft will help low clouds linger through the end of the period. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 430 AM Tuesday...The cold core upper closed low, extending across the FA at it`s furthest southward extent on Wed, will produce variably cloudy skies across the area especially during the heating of the day on Wed. At this point, looking at cold and patchy to occasional liquid rain with the possibility of graupel or pea size hail from the embedded stronger showers. Temps Wed into Wed night will run a conservative 10 to 15 degrees below normal. And there will be the increased potential for min temps Thu morning dropping into the 30-35 degree range and the same holds true for Friday morning. Have been favoring the cooler NAM MOS Guidance of late which has been consistent between model run times. The HWO references the possibility of freezing and/or frost issues come Thu and Fri mornings. The upper low is progged to pull away Thursday, in it`s wake the FA will remain under control of a decent amplified longwave upper trof with NW flow thru the atm column. The upper trof axis will remain primarily east of the FA this period. Sfc winds will remain active thruout this period due to a decent sfc pg across the FA due to deepening low pressure moving into the Canadian Maritimes and a nearly 1030mb high situated along the Gulf Coast States. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 300 PM Sunday...Although I would not discount a few flurries as potent shortwave swings through the back end of the upper trough early in the period, the moisture will be very limited. Therefore will not include any pcp in forecast early Thurs morning as upper trough swings off the coast. CAA continues through Thurs into Friday in strong NW flow as high pressure builds in from the north. The 850 temps drop down around -4c and do not return above 0c until Sat. Temps will drop into the 30s most places with some frost or freeze potential in spots again early Fri morning. Temps both Thurs and Fri may not reach above 60. Low pressure system will brush the Carolinas Fri night into Sat as it moves toward the Mid Atlantic coast. This will produce increase in clouds and greater chc of rain across the area late Fri into early Sat. The latest model runs show a possible wedge type scenario setting up for the weekend with clouds and periods of rain possible. Overall, the weather may turn out to be cooler and more unsettled than originally forecast. && .AVIATION /10Z TUESDAY THROUGH SATURDAY/... As of 06Z...Active period on tap with a couple rounds of convection expected during the next 24 hours. First will arrive during the next few hours with a mid-level disturbance pushing a line of showers and thunderstorms west to east across the area. This line should move off the coast around 12Z, followed by a period of drying. Strong southerly flow today increases instability and an approaching cold front/low pressure combo this afternoon will set off another round of showers and thunderstorms. There is an enhanced potential for severe weather in the afternoon with wind and large hail being the biggest threats. Second batch of convection should exit the coast by 00Z but low clouds may linger through the end of the TAF period. Have high confidence that IFR conditions will be experienced at all terminals, but the convective nature means duration will be limited and timing will be difficult to pin down. Extended outlook...Periods of MVFR/IFR through Wednesday. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 3 AM Tuesday...Southerly flow will develop and then increase today as low pressure develops to the west. Gradient will supports southwest winds of 15 to 20 kt into this afternoon. Further strengthening of the low will push speeds close to 25 kt with gusts in excess of 30 kt. Increasing southerly flow will build seas across the waters today and tonight. 6 ft will be possible in some areas as early as mid to late afternoon and have decided to raise a Small Craft Advisory for all zones starting at 5 PM and lasting well beyond the end of the period. There is potential for 10 ft seas in isolated spots open to extended southerly fetch late tonight. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 430 AM Tuesday...Not one of your better 2 day fcst for spending time on the open Atlantic waters. A decent sfc pg will basically keep a hold of the local waters thruout this 2 day period. This a result of the upper low and associated sfc low pulls away to the NE while a nearly 1030mb high moves along the Gulf coast states. This will result in a west but mainly NW flow across the local waters with speeds of 15 to 25 kt with gusts to 30 kt. With mainly an offshore NW trajectory, the local waters will see a decent range of significant seas with 1 to 4 ft within 10 nm of the coast and 4 to 7 ft at 10 to 20 nm off the coast. Dominating periods will run 4 to 6 seconds. Will need to monitor for Gales and won`t take much for them to occur. LONG TERM /FRIDAY THROUGH SUNDAY/... As of 300 PM Monday...Cold and dry high pressure will extend down over the local waters Friday through Saturday. Strong off shore flow up to 15 to 20 kts early Thurs will weaken and become more northerly through the period down to 10 kt or less by Sat. This will allow seas to subside from close to 3 to 5 ft early Thursday down less than 3 ft by Fri aftn into Sat. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory from 5 PM this afternoon to 6 PM EDT Thursday for AMZ250-252-254-256. && $$ SYNOPSIS...DCH NEAR TERM...III SHORT TERM...DCH LONG TERM...RGZ AVIATION...III is the U.S. government's official web portal to all federal, state and local government web resources and services.