Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 182047 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 447 PM EDT Mon Mar 18 2024 .SYNOPSIS... A vigorous upper-level disturbance and reinforcing surface cold front will move across NC early tonight. Canadian high pressure will follow and build across the Southeast through Tuesday. && .NEAR TERM /THROUGH TONIGHT/... As of 345 PM Monday... A deepening positively tilted upper level trough over the OH valley this afternoon will continue to tilt overnight tonight as it become more neutral by early Tuesday morning and positioned off the Mid- Atlantic coast. A the surface, the cold front is now well off shore this afternoon but mid and high clouds are still streaming across much of the region this afternoon. As the upper and surface trough moves over the OH valley, more clouds will move in over night, but clear out by Tuesday morning. Winds this afternoon are generally W/NW minus a few areas in the Sandhills and S. Coastal Plain still reporting a SW wind. By late evening and continuing into the overnight hours, the entire region is expected to be NW winds 10-15 mph and gusts of 20-25 mph mainly due to the mid/upper trough moving across the region overnight and supplemental mixing to the surface. Temperatures tonight will be the coldest of the forecast with lows ranging in the upper 20s along the VA border and low to mid 30s elsewhere. The growing season has begun in southern portions of Central NC, and with high confidence that temperatures will be between 29 and 31 degrees in some SW central NC counties, A Freeze Warning is valid tonight at midnight through Tuesday 9am. Everyone in the Freeze Warning area should take extra time to protect their tender plants/crops from the sub-freezing temperatures tonight. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
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As of 400 PM Monday... Strong flow aloft will develop Tuesday with a strong ridge along the West Coast and a deep low across SE Canada. At the surface, high pressure will build further east into the Deep South, switching surface flow from westerly to southwesterly across central NC. Winds will strengthen during the day due to the approaching surface high and a deep low moving SE, just north of the Great Lakes. Wind gusts of 20 to 25 mph are possible across much of the area. A dry airmass across the region will help dew point temperatures drop into the teens Tuesday afternoon, and with highs approaching the mid to upper 50s, relative humidity will lower to 20 to 30 percent across most areas. With dry fuels in place across much of the area, an Increased Fire Danger Statement has been issued for the northern Piedmont, Coastal Plain and eastern Sandhills for late in the morning through early evening. Winds will somewhat diminish in the evening, and with clear skies, good radiational cooling will make for a chilly night with lows near normal to 5 degrees below normal. Increasing thicknesses will keep most areas from dropping below freezing.
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&& .LONG TERM /WEDNESDAY THROUGH MONDAY/... As of 320 PM Monday... By Wednesday morning, low pressure will be centered over southeastern Ontario with a cold front extending to the southwest, with the influence of high pressure contained close to the Gulf Coast. The cold front will move across the area from northwest to southeast during the afternoon/evening hours, bringing an increase in wind during that period. The dry conditions that have been present through the week will continue both Wednesday and Thursday, although the wind speeds will be less behind the front on Thursday. The combination of higher wind and low relative humidity could bring an increased fire danger on Wednesday. The frontal passage itself will not bring any precipitation itself as there won`t even be much moisture for cloud cover. Behind the cold front, high pressure will extend southeast from central Canada into the Carolinas on Thursday. The high will shift east Thursday night, and by Friday morning, rain will be approaching the area from the southwest related to a developing low over the Gulf of Mexico. The GFS/GEFS has consistently remained a quicker solution compared to the ECMWF/EPS, especially in regards to the low center, but there is enough agreement between models to increase pops to likely for all locations except the northwestern quadrant of the forecast area Friday afternoon/night. The 12Z GFS shows the low over the Delmarva Peninsula Saturday morning, while the 12Z ECMWF still has the low center off the coast of Georgia. Will have pops decreasing through Saturday and Sunday, keeping some pops in case the slower European solution does verify. All models agree that precipitation will have moved offshore by Sunday night and Monday as high pressure builds over eastern Canada and a ridge extends south along the East Coast. There is high confidence that Wednesday will be the warmest of the next seven days in advance of the cold front, with highs ranging from the mid 60s to the mid 70s. Temperatures should be at or below normal through the rest of the forecast. The day with the most uncertainty to the high temperatures is Friday, as there could be a short-lived cold-air damming episode with high pressure briefly over New York as the Gulf of Mexico low advances northeast. Overnight lows will be above freezing throughout the extended period, and no need for frost/freeze headlines is anticipated. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... As of 200 PM Monday... VFR conditions expected to continue through the next 24 hours. Mid and high clouds are streaming across the region as an upper level trough moves across the region today and tonight. Gusty winds of 15 to 20 kts are expected to continue this afternoon and into the overnight hours. Surface winds of 5 to 10 mph this afternoon will shift from a northerly wind to west-northwest wind by the late evening. A few areas of virga could occur at the 3 eastern sites overnight but no flight restrictions are expected. Otherwise skies will clear early Tuesday morning through the afternoon. Outlook: LLWS will be possible Tues night into early Wed as winds at 2k ft increase to 30-40 kts. A dry cold frontal passage will bring a wind shift out of the NW late Wed into early Thurs. A storm system approaches the area Fri afternoon into Sat bringing a high chance for sub-VFR conditions. && .FIRE WEATHER...
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As of 400 PM Monday... Elevated fire weather conditions are possible at times through mid- week as relative humidity drops to 20 to 30 percent, and wind gusts increase to 20-25 mph. Relative humidity will drop to the aforementioned values in the afternoons through Thursday, however wind gusts of 20 to 25 mph are mostly expected Tue and Wed afternoons. With dry fuels across most areas, an Increased Fire Danger Statement has been issued for the northern Piedmont, Coastal Plain and eastern Sandhills for late Tue morning through the early evening. Refer to your local burn-permitting authority on whether you may burn. If you do burn, exercise extreme caution.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... Freeze Warning from midnight tonight to 9 AM EDT Tuesday for NCZ073>076-083-084. && $$ SYNOPSIS...MWS NEAR TERM...CA SHORT TERM...JJT LONG TERM...Green AVIATION...CA/Swiggett FIRE WEATHER...JJT

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