Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 271055 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 655 AM EDT Tue Jun 27 2017 .SYNOPSIS... A weak upper level system will bring a few showers to western NC today, but otherwise dry and cooler weather will continue through Wednesday. High pressure moves off the East Coast on Thursday with warm and moist air moving north from the Gulf through next weekend. This brings back the daily chance of afternoon and evening showers and thunderstorms through the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 640 AM Tuesday: sct mid to high clouds continue to stream across the region from the west this morning. Temps have bottomed out 1 to 2 categories below climatology for late June, with dewpts below climo as well. I kept some slight chance PoPs in the fcst over the next 6 to 8 hrs as the weak cold front pushes thru the CWFA, however it`s doubtful that most locations will see any measurable precip. Otherwise, the near-term fcst is mostly dry with notably cool temps for late June. Broad upper-lvl trofing will remain over the Eastern CONUS thru the period with ridging over the west. An embedded shortwave will round the backside of the trof and move over the fcst area later this morning and afternoon. It will lift to the NE by the end of the period early Wed as heights begin to recover over the southeast. At the sfc, Canadian high pressure will steadily slide SE today and tonight and should be centered just to our north by early Wed. As the upper shortwave approaches aloft, a weak cold front will move thru the CWFA later this morning bringing some slight chances for precip, mostly over the higher terrain. The latest model soundings are looking pretty dry and lack any notable instability as the front moves thru. The only things going for it will be the favorable upper-lvl support from the shortwave and some better/deeper moisture upstream that could allow showers to translate across the NC/TENN border and into the CWFA. With the sfc high building in behind the front, the afternoon should see skies clearing and high temps well below normal for late June, especially over the northern zones. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 230 AM EDT Tuesday: Weak northwest flow aloft will be in place at the start of the short term in the wake of the shortwave trough axis. Cool high pressure will be centered over the Appalachians on Wednesday, leading to another day of below-normal temperatures. The high will move offshore late in the day, with moist return flow ensuing. A shortwave and associated moisture will drift up from the Gulf, and weak isentropic upglide ahead of this will bring a return of diurnally-driven thunderstorms to the mountains and portions of the Upper Savannah Valley on Thursday. While temperatures will remain below seasonal normals, the increase in low level moisture will bring humidity levels up with a return to more muggy conditions. This Gulf moisture advection will continue to propagate east and toward the Carolinas as the surface high pushes farther out to sea. Meanwhile a stronger shortwave will push out of the Canadian Rockies underneath a longwave trough over central Canada. This will push a weak front through the center of the country which will be approaching the Ohio Valley toward the end of the period. By Thursday night, should see lows pretty much near seasonal normals with dewpoints continuing to rise. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 300 AM EDT Tuesday: Warm moist advection will continue as we start the period with southerly flow around the western periphery of an Atlantic high, with surface low pressure working its way across the Great Lakes and an attendant front pushing toward the Ohio Valley. Should see a fairly diurnal trend to convection on Friday with highs still a few degrees below seasonal normals, but as the front approaches on Saturday, pops trend up to likely in the mountains with continued increasing dewpoints resulting in a return to above-normal overnight lows (with highs still hovering a couple of degrees below). The front will become quasi-stationary, hanging around the area through the weekend, with another enhancement to diurnal pops on Sunday. Minimal shear associated with the upper trough will be in place so could see some slight organization to the convection, but generally expect pulse convection, with sbCAPES generally between 1500-2000 J/kg (certainly not unusual for this time of year). Do not see a significant reason for increased severe potential other than the fact that convection itself, severe or not, may be slightly more widespread. The front pushes south by Monday but as an upper ridge builds into the Lower Mississippi Valley, it will lift the SW portion of the front back north as it connects with yet another shortwave diving through the Upper Midwest, so expect near-normal temperatures and a continued enhancement in diurnal pops through the pend of the period. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... At KCLT and elsewhere: expect VFR conditions to prevail thru the 12Z taf period. Broad sfc high pressure will remain centered to our NW and slide just to our north over the next 24 hours. Winds remain calm or near calm so far this morning, but should shift to a NLY and then NELY direction and pick up in speed as a reinforcing cold front moves over the area. Isolated SHRA are possible across Western NC with this front over the next 6 to 8 hrs or so, however the only site that could be impacted is KAVL, and any restrictions are unlikely. Outlook: light winds and VFR conditions should continue through mid week. Moist, southerly return flow will develop around the offshore ridge on Thursday. As a result, typical summertime conditions will return by the end of the work week, with mainly late afternoon/ evening SHRA/TSRA causing possible restrictions. Confidence Table... 11-17Z 17-23Z 23-05Z 05-06Z KCLT High 100% High 100% High 100% High 100% KGSP High 100% High 100% High 100% High 100% KAVL High 100% High 100% High 100% High 100% KHKY High 100% High 100% High 100% High 100% KGMU High 100% High 100% High 100% High 100% KAND High 100% High 100% High 100% High 100% The percentage reflects the number of guidance members agreeing with the scheduled TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...TDP NEAR TERM...JPT SHORT TERM...TDP LONG TERM...TDP AVIATION...JPT is the U.S. government's official web portal to all federal, state and local government web resources and services.