Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 251044 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 644 AM EDT Sun Jun 25 2017 .SYNOPSIS... A cold front will settle southeast of the region this morning with drier and cooler air beginning to spread in from the northwest. These conditions are expected to persist over the forecast area through much of the week as high pressure remains to our north. As the high moves offshore, moist southerly flow will return towards the end of the week. && .NEAR TERM /THROUGH TONIGHT/...
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As of 630 AM EDT Sunday: Have updated wx grids to add in some isolated sprinkles generally south of I-40 and west of I-77 this morning. A very weak shortwave embedded in the flow aloft, as well as a bit of a finger of an upper jet streak, has allowed some light rain to form from AL into N GA, with some sprinkles (or at least light radar returns) spreading up toward the Blue Ridge. These should be short-lived. Cloud cover remains a little higher than expected across portions of the Upstate, specifically the Upper Savannah Valley, and made some adjustments there. Other changes are mainly for aviation-related parameters. Otherwise, big change starts today in the wake of a cold front, which had worked its way south of the forecast area by AFD time. Longwave upper trough axis just to our west will continue to push east, with thicknesses decreasing as surface high pressure begins ridging in from the west. The trough will make little progress through the period, but the airmass change will be felt in the form of much lower dewpoints, especially tonight. High temps today will likely be similar to those yesterday (due to less cloud cover) except maybe in the mountains, though this is still a handful of degrees below seasonal normals. Overnight lows tonight will be a good 5 or so degrees below what we`ll see this morning, and ranging anywhere from 3-8 degrees below seasonal normal. Overall, a really pleasant day for late June.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 250 AM EDT Sunday: the short-term fcst picks up at 12z on Monday with longwave upper trofing centered over the Great Lakes and steep upper ridging in place over the Western CONUS. By early Tuesday, an upper shortwave will dig southward on the backside of the upper trof, providing increased upper-lvl divergence just ahead of it. The shortwave axis is expected to move overhead Tues afternoon and then offshore by early Wed with heights beginning to recover in its wake. At the sfc, a lingering frontal bndy will be located over the SC Coast early Monday and slowly drift offshore later in the day/evening. The rest of the period is marked by the Canadian High sliding SE and towards our area on Tuesday before ending up just to our north by the end of the period, 12z Wed. As for the sensible fcst, most of the period should be dry. I do have some slight chance PoPs on Tues as the upper shortwave approaches the area and produces favorable ascent especially over the higher terrain. Temps will be 1 to 2 categories below normal for late June. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 235 AM EDT Sunday: the extended fcst picks up at 12z on Wednesday with an upper shortwave moving off the Atlantic Coast. As it does, heights begin to rebound over the fcst area as upper ridging starts to build to our south. Another longwave upper trof approaches the Great Lakes on Friday and then gradually slides to our north over the weekend acting to flatten the ridge to our south. At the sfc, broad high pressure will be centered just to our north by early Wednesday with below normal temps in place over the region. The high will slide off the Atlantic Coast on Thursday putting the CWFA back under warmer and more moist SLY low-level flow for the end of the work week. A cold front will approach the fcst area from the west on Saturday, but is not expected to move thru the CWFA until the end of the period on Sunday. As for the sensible wx, Wednesday should be dry with the high over us. Thurs and Fri will see a return to a more typical summertime pattern with slight to solid chances for TSRA each day. Chances for widespread TSRA increase on Sat as the front moves into the fcst area. Temps and dewpts will start out about a category below normal and steadily warm thru the period with values reaching normal by the end of the work week. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/...
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At KCLT and elsewhere: VFR for all but KAND this morning, where an area of LIFR cigs has persisted. These cigs aren`t far from KGSP/KGMU, and even some a county south of KCLT, but with the front continuing to push southeast, should not impact these other sites, and should see improvement at KAND in the next couple of hours. But generally only some passing high to occasionally mid-level clouds through the period. N winds shoudl prevail through the period, fairly light this morning but picking up around or just above 5kt this afternoon, though KAVL should see some low-end gusts. Outlook: Expect light winds and mostly clear skies through Thursday as high pressure dominates the weather. Confidence Table... 10-16Z 16-22Z 22-04Z 04-06Z 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 Low 44% 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:
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&& .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...JPT NEAR TERM...TDP SHORT TERM...JPT LONG TERM...JPT AVIATION...TDP is the U.S. government's official web portal to all federal, state and local government web resources and services.