Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 281048 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 648 AM EDT Sun May 28 2017 .SYNOPSIS... Warm and humid air will remain over our region through at least Monday, as high pressure settles east of the Florida coast. A cold front will slowly approach from the northwest, but will struggle to push through the area during the middle of next week. && .NEAR TERM /THROUGH TONIGHT/...
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As of 645 AM EDT: A broad area of showers will move east across the area this morning, but TSRA should remain to our south. The forecast area will remain solidly in the MCS tracks today from convection developing from the west in the unstable elevated mixed layer. Convection allowing models show another round of convection crossing the area late this morning and early afternoon. Another round may cross NC late this afternoon and early evening. Precip will become more isolated with each round moving over. PoP has been adjusted to reflect this. However, there is quite a bit of uncertainty after the initial round of showers given the potential that instability could be limited due to less heating from lingering convective debris. Shear should be more than adequate for organized/severe convection, if the atmosphere can become moderately unstable once again. The best chance for organized convection will be along and south of the I-85 corridor later this morning and early afternoon with the forcing from the MCS to our west. The best chance later this afternoon and early evening will be along and near the I-40 corridor. Of course, all this is predicated on becoming moderately unstable. Convection should taper off later this evening with mainly isolated convection across the mountains overnight. Highs today will be up to 5 degrees above normal with lows tonight up to 10 degrees above normal.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 230 AM Sunday: A large upper low will slowly wobble/drift eastward across the Great Lakes and then north toward Hudson Bay, keeping a longwave trof axis across the MS to OH Valleys thru Tuesday. There will also be a nice jet streak extending from the OH Valey to the northern Mid-Atlantic, placing our area within the right entrance region. Models do show periods of better upper divergence, both on Monday and Tuesday. At the surface, a cold front will stall just west of the Appalachians Monday, and struggle to push across the area Tuesday. This set up should keep the forecast area unsettled. Models agree on decent sbcape on Monday, especially across the Piedmont, with bulk shear continuing around 40-50 kts. So organized convection will be possible again, with the new Day 2 outlook placing a slight risk across the I-85 corridor and south, and marginal risk to the north. On Tuesday, both the cape and the shear look weaker. But with continued upper support and plenty of moisture, we will probably see another round of convection, just with a lower severe threat. Temps will continue to be above normal. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 300 AM Sunday: a broad longwave trough axis will finally shift east across the CWFA on Wednesday, bringing a second cold front in from the west. So scattered aftn-eve showers and storms are expected again. Temps look to be slightly cooler, as thicknesses fall with the trough. Shear looks to increase somewhat from Tuesday, but CAPE remains muted in the guidance. So the severe threat looks low at the moment, but may be a bit higher, if we manage to see better CAPE. Thursday looks to be the quietest and coolest day of the medium range, as a cold front actually pushes east of the mountains and ushers in some drier air. This will be short-lived, however, an upper low near Hudson Bay will rotate back south into the Great lakes and starts to set up another shallow trough over the MS Valley to the OH Valley. Surface high pressure will quickly exit off the Mid-Atlantic coast, and deep-layer SWLY flow brings Gulf moisture back in across the region. Temps warm back above normal and a return to slightly above climo diurnal convective coverage is expected for Friday and Saturday. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/...
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At KCLT and Elsewhere: A broad area of showers will spread across the area this morning. Cannot rule out some MVFR, but low VFR is more likely. After this area of showers moves through, convection may redevelop and move east across the area late this morning and early afternoon. Then another round may move across NC late this afternoon and early evening. Timing is very tricky and have picked the most likely timing, but this is subject to change through the day. Convection ends this evening. Any fog overnight is most likely to occur at KAVL. W to NW wind becomes SW and gusty this afternoon. Winds turn back to W to NW and light this evening and overnight. KAVL will see N to NW winds through the period. Outlook: Thunderstorms and associated restrictions, mainly of the afternoon/evening variety, as well as the potential for areas of morning fog and/or low stratus will continue through at least the middle of next week. 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 83% High 100% High 100% High 100% KHKY High 100% High 100% High 100% High 100% KGMU High 100% High 97% 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:
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&& .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...ARK NEAR TERM...RWH SHORT TERM...ARK LONG TERM...ARK AVIATION...RWH is the U.S. government's official web portal to all federal, state and local government web resources and services.