Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 182056 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 350 PM EST Wed Jan 18 2017 .SYNOPSIS... High pressure will build over the region tonight and Thursday. A wave of low pressure is expected to move in from the southwest Thursday night and Friday. This will be followed by a strong storm system for late in the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 300 PM Wednesday... Sunny and warm conditions will prevail this afternoon with delayed CAA behind the front. The cold air advection will gradually win out this evening allowing from cooling from the readings in the 60s/70s this afternoon. Lows tonight will be driven by a combination of cold advection and radiational cooling, in the 40-45 range, with clear skies. && .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... As of 300 PM Wednesday... An upper level ridge and associated surface high building into the region from the west tonight will be situated directly over the Carolinas/Mid-Atlantic on Thursday. As such, expect a pleasant/ sunny day with above normal highs in the upper 50s to lower 60s. Widespread precipitation is expected to develop upstream over the Deep South/TN Valley during the day Thursday as a potent upper level low lifts NE through the Central Plains toward the Upper Great Lakes. As a result, clear skies will quickly give way to increasing cloud cover by sunset as mid/upper level ceilings advect downstream of the mountains. Southerly return flow will quickly strengthen over western portions of the Carolinas as shortwave energy rounding the base of the upper low in the Central Plains Thu afternoon ejects E/NE through the Deep South into the Carolinas Thursday night. Expect a further increase in cloud cover overnight as mid/upper level ceilings are complimented by low ceilings assoc/w strengthening warm advection. In fact, light rain will be possible by sunrise (09-12Z) Friday morning in the Western Piedmont as moisture deepens via warm advection in the presence of DPVA (assoc/w the aforementioned shortwave energy). Low temps Thu night may be met by Thu evening, particularly in the west, as a result of warm advection and thickening cloud cover. Expect temps ranging from the low/mid 40s E/NE to upper 40s W/SW. -Vincent && .LONG TERM /Friday through Wednesday/... As of 350 PM Wednesday... The first wave of low pressure in the strengthening jet aloft is forecast to dampen out Thursday night and Friday as it tracks NE across the TN Valley to the mid-Atlantic coast. Likely POP for rain expected, especially in the west and north for a period late Thursday night and early Friday, with lesser chance POP in the SE. QPF with the weakening system should be 0.25 or less in the NW, with 0.10 or less SE. Skies should return to variably cloudy Friday afternoon and evening between systems. Mild temperatures will continue with lows in the 40s. Highs Friday in the 60s, except upper 50s NW. Friday night through Saturday... The next system is forecast to approach from the SW late Friday night and Saturday. The Gulf of Mexico is forecast to be wide open as the flow between the high pressure off the SE coast and the deepening upper storm out west increases from the south. A leading warm front is expected to lift from the Gulf Coast states northward into our region Saturday. Strong WAA and overrunning will result in a large shield of rain that is expected to over- spread much of our region late Friday night and Saturday. The highest POP and QPF for now will be across the west and south portions of the Piedmont Friday night, gradually spreading north Saturday. Mild temperatures will become warmer in the SE later Saturday as the warm front tries to lift into the region. It appears it will have some In-Situ Damming resistance over the Piedmont; however, there should be rather minimal damming this time due to the lack of a strong enough high pressure and/or dry air for evaporative cooling to support anything more than some weak In-Situ Damming in the Piedmont Saturday. There should still be some highs holding in the 50s NW, ranging to 60s SE Saturday with rain likely. Saturday night through Monday... Heavy rain and the chance of thunderstorms the main hazards for this period. Severe storms possible in the warm sector by late Sunday. The very potent mid/upper level system is expected to have the potential to produce fairly wild weather conditions (warm and stormy) for our region (for January standards). The main storm is expected to strengthen as it lifts out of the FL Panhandle Sunday toward our region Sunday night. A stronger warm front is forecast to lift into our southeastern counties Sunday afternoon/night as the surface low deepens. Widespread rain, some heavy is expected Saturday night and Sunday. Temperatures should hold in the 50s Saturday night, then reach into the 60s Sunday. The readings may hold or come up even more Sunday night depending on the warm front timing. The main low pressure track is still uncertain and this will play a role in our severe storms threat late Sunday and Sunday night/Monday morning. Widespread rain should hold down the instability. However, dew points are forecast to surge into the 60s in the warm sector Sunday night. If this warm sector does surge into the region (or a portion of the region), the likelihood of severe weather will increase dramatically. There is still much uncertainty with these details and they will be hashed out in later model runs. For now, we will continue to carry periods of rain Sunday and Sunday night. There will be a chance of thunderstorms, and severe weather is possible. The timing would be late Sunday afternoon into Monday morning (with the triple point low and cold frontal passage expected Monday morning) ending the storminess. We will broad brush the heavy rain and thunderstorm potential hazards in the entire region - until the details become more certain in later forecasts. Behind the front Monday, we will keep slight chance POP Monday, with partly sunny skies returning. Very mild to warm air will lead to some 70s for highs as CAA will be blocked by the Appalachians (negatively tilted storm system lifts north of the region). True CAA will likely lag the front until Monday night and Tuesday. Even so, lows will be in the 40s. Highs are expected in the 60s Tuesday (Pacific origin air mass). A turn to colder weather is anticipated by recent model trends by late next week. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... As of 100 PM Wednesday... 24-Hour TAF period: VFR conditions /clear skies/ will prevail through the TAF period, with winds becoming light/variable overnight as high pressure builds over the region from the W/NW. Long term: Sub-VFR conditions will be possible late Thu night or Friday morning as southerly return flow strengthens over the Carolinas. Adverse aviation conditions may prevail Fri through much of the upcoming weekend as a series of upper level disturbances track across the region. -Vincent && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Badgett/Vincent NEAR TERM...Badgett/Vincent SHORT TERM...Vincent LONG TERM...Badgett AVIATION...Vincent is the U.S. government's official web portal to all federal, state and local government web resources and services.