Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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878 FXUS62 KGSP 011904 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 304 PM EDT Sat Jun 1 2024 .SYNOPSIS... Dry high pressure moves off the Carolina coast on Sunday with warming temperatures and increasing moisture. A typical summer pattern will develop during the first half of the week with daily afternoon thunderstorm chances. Showers and thunderstorms will likely increase in coverage for Wednesday and Thursday as a cold front approaches our area, with drier weather expected to return by the end of the week. && .NEAR TERM /THROUGH SUNDAY/... As of 2:25 PM Saturday...high clouds continue to expand eastward across the western Carolinas with lower clouds still to our west. Over the past few hours, shower coverage just to our west has di- minished with more daytime heating. Overall trends wrt the shower coverage haven`t changed significantly, with coverage over our area not expected to increase substantially until overnight. Low temps early Sunday should remain near-normal due to increased cloud cover tonight/overnight and higher dewpts. Otherwise, upper level ridging will deamplify and shift east and off the Atlantic Coast this evening and early Sunday as an upper shortwave moves over our area from the west. At the sfc, broad high pressure will continue to gradually move off the Atlantic Coast thru the near-term period as a moist frontal boundary moves into the Western Carolinas from the west. Forcing ahead of the above-mentioned upper shortwave has already reached our western zones, however more substantial moisture advection from the Atlan- tic will be slow to saturate the lower levels. The latest near-term guidance still generates the bulk of the low-level moist transport after midnight. Nonetheless, some iso to sct showers will likely materialize across the NC mtns before that. More widespread precip will spread over our fcst area overnight, but with very limited instability and meager mid-level lapse rates thru the morning hrs, thunder is unlikely until Sunday aftn, with the severe potential still looking minimal at best for Sunday. Highs should remain 1 to 2 categories below climatology. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 200 pm Saturday: The upper air pattern will become increasingly anticyclonic across our region early in the short term, as a weak ridge builds from the Deep South through the Great Lakes. As a result, a deep moisture plume will gradually shunt east of the forecast area early in the period. In the interim, scattered coverage of showers along with a few storms will continue into Sunday evening before steadily tapering off. Decreasing deep layer moisture will yield less in the way of cloud cover, but also improved potential for destabilization Monday afternoon. Diurnal convection is forecast to initiate...esp across the high terrain. While coverage is expected to be more limited than on Monday, sbCAPE of around 1500 J/kg should allow for a few stronger storms, with perhaps a stray pulse severe storm not completely out of the question. With little change in the pattern and thermodynamic profiles expected, Tuesday should be very similar to Monday, with scattered diurnal convection expected, and perhaps a slight uptick in the threat for a pulse severe storm with hotter conditions expected. The first half of the period is expected to see temps average around...or slightly above normal...while the short term is expected to end around 5 degrees above climo. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 215 pm Saturday: An expansive/deep upper low will wobble from the Canadian Prairie at the start of the period to the Great Lakes by Thursday evening. Height falls associated with a vorticity lobe lifting ahead of the low is expected to send a frontal boundary into the region by late Wed, enhancing convective chances across the southern Appalachians and vicinity Wed into Wed night. Indications in global model guidance are that the afternoon will see at least moderate instability, albeit in a modestly sheared environment. A few strong-to-severe pulse storms and/or multicell clusters will be possible. An additional round of storms is possible Thursday, although this is a bit more uncertain, as some global model guidance suggests drier air will be filtering into the area in the wake of the frontal boundary Thu afternoon. PoPs are generally advertised in the solid chance range during that time. The latter half of the period should become more inactive as lower theta-E air advects into the region. PoPs for Fri/Sat are limited to token slight chances, mainly over the mtns. Temperatures are forecast at around 2-4 degrees above normal through the period. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... At KCLT and elsewhere: Expect VFR conditions to continue thru the 18z period at all taf sites except at KAVL and KAND, where cigs are expected to drop below VFR towards the end of the period late tomorrow morning. The other terminals could see some lower cigs by that time, but more than likely they will remain low-end VFR thru the period. Otherwise, VFR clouds will gradually lower tonight and early Sunday with sct showers approaching the area by that time. I have PROB30s for shra at all sites beginning Sunday morning and PROB30s for tsra by the early afternoon once some in- stability is present. Winds should continue to favor a SLY to SELY direction thru the period, becoming weaker later tonight and then picking back up moderately by the early afternoon tomorrow. Outlook: Diurnal shower and thunderstorm chances will linger thru the middle of next week. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...DEO NEAR TERM...JPT SHORT TERM...JDL LONG TERM...JDL AVIATION...JPT