Sunrise 6:30 AM   Sunset 8:09 PM Moonrise 1:00 AM   Moonset 10:43 AM

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FXUS62 KGSP 301103 AFDGSP

Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 703 AM EDT Tue Apr 30 2024

SYNOPSIS
A cold front will push through the forecast area today bringing scattered showers and thunderstorms. Dry and warm high pressure builds across the region Wednesday through Thursday, before another active frontal system moves in Friday and lingers through the weekend.

NEAR TERM /THROUGH TONIGHT/
As of 6:35 AM EDT Tuesday: A thicker deck of mid-level clouds con- tinues to spread further east over our area. A broad area of sct to numerous showers, with some embedded thunderstorms, continues to gradually make its way eastward and is now moving into our western-most zones.

Otherwise, an embedded upper shortwave will approach the western Carolinas this morning and gradually move over our fcst area later today and into early Wednesday, helping to push upper ridging off the Atlantic Coast as the near-term period is ending. At the sfc, broad high pressure will remain centered off the Southeast Coast with light, SLY low-level flow over our area this morning. At the same time, a weak cold front will approach our CWA from the west and move thru our area this afternoon/evening. This timing will result in a decent amount of sfc-based instability, on the order of 500 to 1000 J/kg, across much of our area by mid-afternoon.
Thus, numerous showers and sct thunderstorms are expected this afternoon/evening. The instability coupled with the upper short- wave may produce a few stronger storms over our area, but with generally unimpressive lapse rates it's doubtful that any storms will become severe. Regardless, the boundary should be moving east of our CWA by early Wednesday with weak high pressure sliding in behind it as the period ends. As such, PoPs taper off to just a slight chance over the I-77 Corridor by the end of the period, early Wednesday. Temperatures today will moderate by a few deg outside the mtns, with highs near 80 this afternoon. They will be notably cooler over the higher terrain, with highs struggling to reach 70 in the mtn valleys.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
As of 105 AM Tuesday...A mid-level trof axis continues to shift east of the area to begin the short range period. This will give way to a building upper ridge across the east coast, which will control the weather across the FA thru Thu night. Profiles remain quite dry with PWATS remaining below 1.0 inches each day, so along with neg forcing, rain chances are nil with mainly fair-wx Cu each day. Winds will be weakly cold advective as sfc high pressure builds in from the north, yet high temps will reach the low to mid 80s each day in a modifying airmass. With the n/ly to ne/ly flow, sfc dewps and RH values wont increase much, so expect rather nice feeling weather for late April.

LONG TERM /FRIDAY THROUGH MONDAY/
As of 150 AM Tuesday...The ext range forecast remains unsettled as upper ridging finally breaks down in advance of mlvl srn stream energy. The latest op models generally agree on a modest h5 s/w approaching the FA Fri pushing an active sfc bndry in from the west, while sfc ridging breaks down across the nrn GOM supplying very good moisture flux to the system. This wont be a very dynamic system as deep layered shear remains less than 30 kts with only a 60 kt upper jet core arriving by Sun evening. Thermo profiles indicate a saturated column likely with skinny CAPE on the order of 700-1000 J/kg. So, expect some strong thunderstorms each day with high rainfall rates possible. An organized severe threat looks low-end as aforementioned dyno remains low and mlvl LRs area held less than optimal while a highly moist sfc bndry settles across the area thru Sun, possibly into Mon. Low level winds remain s/ly to se/ly each day and temps will remain abv normal, with a drop off to near normal levels Sat due to a better chance of widespread cloudiness and precip.

AVIATION /11Z TUESDAY THROUGH SATURDAY/
At KCLT and elsewhere: Expect VFR conditions to persist thru day- break as the western edge of a sfc high lingers over our area. A cold front will approach from the west this morning and move thru the western Carolinas this afternoon and evening. Rain chances increase across the western terminals (KAVL and the SC Upstate terminals) by late morning with VCSH beginning just before noon.
Being further east, KHKY and KCLT should remain dry a bit longer with any showers reaching them a few hrs later. Sct thunderstorms will be possible during the afternoon and evening across the fcst area. Thus, I have PROB30s for TSRA at all terminals beginning in the afternoon and going into the evening with lingering VCSH. Winds will remain light to calm overnight and into the morning. They will pick back up by late morning and continue to favor a S to SW direc- tion thru the period. Low-end gusts are possible this afternoon, especially at KCLT and KHKY, where I included them in the taf.
Otherwise, cigs should generally remain VFR outside of any TSRA.

Outlook: Scattered showers and thunderstorms will remain possible thru late tonight. More numerous showers and storms are expected on Saturday ahead of a cold front.

GSP WATCHES/WARNINGS/ADVISORIES
GA...None.
NC...None.
SC...None.

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