Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 200539 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 145 AM EDT Fri Apr 20 2018 .SYNOPSIS... Chilly high pressure will build south over the region tonight through the weekend. Low pressure is forecast to track east across the Gulf Coast states this weekend, then turn up the eastern seaboard early next week. This will bring unseasonably cool and wet conditions early to mid next week. && .NEAR TERM /TONIGHT/... As of 1010 PM Thursday... ...Frost advisory remains in effect tonight-early Fri for the NC Piedmont and northern Coastal Plain... A mid-upr low centered over srn Ontario this evening will move east across the Northeast tonight. While it does so, one final perturbation now over Lake Erie will amplify sewd and offshore the nrn middle Atlantic coast by 09-12Z. Strong height rises aloft centered over the OH Valley per 00Z upr air data will follow and overspread the middle Atlantic states through early Fri, with resultant subsidence and mainly clear skies over cntl NC. At the surface, the segment of the cold front that crossed cntl NC earlier Thu, evident as a fine line in regional radar imagery, was analyzed at 02Z from near Charleston to Aiken, SC. Behind the front, a weak "break off" high has begun to form over n-cntl NC and s-cntl VA. This high was separated from the parent 1033 mb high centered over the upr Midwest by a lee trough in the immediate lee of the srn- cntl Appalachians. After the warmth of the past couple of days, it feels sharply cooler out this evening, when accounting for both temperatures in the 40s- 50s and a continued breezy nnwly surface wind - up to 20-25 mph still over the Sandhills and srn Coastal Plain. These winds will gradually subside during the next several hours, and particularly so by daybreak Fri, as the center of the aforementioned break off high builds directly overhead. While some periods of calm and good radiational cooling will result, the brevity and late occurrence of such conditions should keep temperatures from realizing full cooling potential. As such, previously forecast lows in the 33 to 40 degree range, coldest in the Advisory area, away from urban areas that are likely to remain in the upr 30s to near 40 degrees, need little/no modification. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... As of 235 PM Thursday... The expansive cP airmass centered over central US will continue to build east into the region through Saturday. This will support dry and cool temperatures. Under sunny skies, daytime highs will average a good 7 to 10 degrees below normal, ranging from lower 60s NE to mid/upper 60s south. With the sfc ridge axis drawing closer to the area, conditions should be favorable for radiational cooling. As such, will undercut statistical guidance with overnight lows in the lower to mid 30s, which will pose another threat for frost. && .LONG TERM /SATURDAY THROUGH THURSDAY/... As of 300 PM Thursday... The weekend is expected to be dry as surface high pressure moves into the mid-Atlantic and New England states. With easterly flow expect temperatures slightly below normal with highs in the mid 60s to near 70 degrees and lows in the 40s. By Sunday afternoon cloud cover will begin to increase from the west as the high slides into a pattern more favorable for cold air damming. On Monday, attention will turn to a low pressure system crossing the deep south which will encroach on central NC from the southwest. With isentropic lift increasing, better chances of some stratiform rain will come into play by Monday afternoon give or take a few hours, which is a much better agreement in model timing than prior simulations. The ECMWF is still the slower of it and the GFS but the differences are much smaller. Once rain chances begin, expect them to continue through Tuesday night when the actual low is progged to cross the eastern half of the state. Lower chances will then continue through Wednesday and into Thursday morning with wrap around precip associated with the back side of the surface low as well as the upper level low which will pass behind the surface low. Therefore expect wet and unsettled conditions through the bulk of the week next week with temps highs in the 60s, moderating into the lower 70s by Thursday. Lows generally in the upper 40s to low 50s. && .AVIATION /06Z FRIDAY THROUGH WEDNESDAY/... As of 145 AM Friday... 24-Hour TAF Period: High confidence VFR conditions will prevail through Saturday. Looking ahead: Expect VFR conditions to persist through the weekend. A storm system is forecast to bring IFR CIGS and VSBYS with rain and fog late Monday or Monday night into Wednesday morning. && .RAH WATCHES/WARNINGS/ADVISORIES... Frost Advisory from 4 AM to 9 AM EDT Friday for NCZ007>011- 021>028-038>043-073>076-083-084. && $$ SYNOPSIS...Badgett NEAR TERM...MWS SHORT TERM...CBL LONG TERM...Ellis AVIATION...Badgett is the U.S. government's official web portal to all federal, state and local government web resources and services.