Sunrise 6:36 AM   Sunset 8:18 PM Moonrise 3:00 AM   Moonset 2:26 PM

  Print   HELP   Reset   Save   Recall

FXUS62 KGSP 040216 AFDGSP

Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 1016 PM EDT Fri May 3 2024

SYNOPSIS
Dry and warm high pressure moves off the Carolina coast as a front approaches from the west then stalls over our region for the weekend. This front will result in periodic thunderstorms and showers starting today and lingering through the weekend. A general summertime pattern sets up early next week, which will likely support scattered thunderstorm development each afternoon.

NEAR TERM /THROUGH SATURDAY/
As of 1010 PM EDT: Ridge axis still present over the SE Coast. Some disorganized bands of convection continue west of the Appalachians in the more unstable area upstream of the ridge, generally ahead of approaching shortwave. Little change in the pattern or vertical profiles tonight, such that a few hundred joules of MUCAPE will linger in southerly flow regime. Thus scattered showers and perhaps a few t-storms are expected to continue in the Smokies and Balsams, south to the Savannah Valley. Isolated cells recently fired up again near upper reaches of Lake Hartwell. At this point, main impacts from any storms are expected to be locally heavy rainfall. Outflow from earlier storms left behind a nearly saturated PBL in some spots, and some locally dense fog can't be ruled out in such areas overnight. With temp trends having stabilized and hi-res guidance having caught up, updated overnight T/Td and revised extent of fog per latest vsby guidance. Southerly flow is weak but should promote moisture advection into the lower Piedmont, possibly bringing fog and low stratus to those areas around dawn even if clouds inhibit radiation fog.

Possibly more notably, the weak moisture advection may promote rapid development of convection around or after daybreak Saturday. Coverage should then increase for that reason and as forcing from the shortwave increases as the day continues. Instability and shear will remain on the weak side, while forecast profiles show an even more saturated atmosphere. This suggests and even less chance of strong to severe storms, with a slight uptick in heavy rain potential. That said, the overall flood risk remains low given the relatively dry antecedent conditions. Highs will be near normal due to clouds and precipitation.

SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/
As of 240 PM EDT Friday: The rest of the weekend looks active right into the first part of next week. A baggy upper trof overhead on Saturday night slowly lifts northeast with a short wave passage, and this bit of lingering forcing will be able to keep shower/thunderstorm activity on a slow wane into the early morning hours. Guidance suggests that it will never die off entirely, so the fcst retains some fairly high precip probs. That sets the stage for Sunday. Models show less forcing, but an uptick in the available buoyancy in the afternoon. That should make for a more thermodynamically-driven day, with better than climo coverage of showers and storms. Forecast soundings off the NAM show some pulse-severe wind damage potential with mid-level dry air and a shallow inverted-V, so it would not come as a surprise if it was a busier day than Saturday. A stronger short wave lifting northeast over the TN/OH Valley regions on Monday will continue to support diurnally-enhanced convection, so we continue with above climo precip probs. Temps look to be on the order of five degrees above normal.

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
As of 143 PM EDT Friday: The bulk of the medium range looks like a summer preview. After a baggy upper trof moves past Monday night, we should spend the remaining week underneath a low amplitude, relatively fast, WSW flow aloft. Within this flow, the model guidance shows a steady train of short waves moving through, mostly around peak heating each day, that will enhance our convective coverage each afternoon/evening. Overall, the air mass shows little change from one day to the next, as a wavy surface front will be strung out to our north in the WSW flow. Buoyancy will be modest and shear will be light, which suggests that chances for severe storms will be relatively low, but in such a pattern we eventually seem to manage to crank out a few pulse severe storms each day. Precip will be spotty and showery, which keeps the heavy rain threat at bay, but eventually there could be a few spots that start to see an increased risk of flash flooding, especially if a more coherent, stronger short wave comes along, such as what the GFS shows next Friday. Lots of uncertainty, though. Temps will remain in that 5-10 degree above normal range for most days, perhaps on the high side of that either Wednesday or Thursday, which one of those days might get a break in the wave train and thus reduced shower coverage and higher temps.

AVIATION /02Z SATURDAY THROUGH WEDNESDAY/
At KCLT and elsewhere: -SHRA will approach KAVL and KAND this evening but chance of impacts small enough no mention is made in their TAFs. Multiple cloud decks above 070 will be seen tonight largely as a result of either convective debris or clouds forced by upstream shortwave. Sfc conditions will be moist tonight where precip outflow occurred Fri aftn, but otherwise low levels remain rather dry and extent of fog will be limited overnight especially given cloud cover. Some instability will persist overnight and new SHRA or even TSRA can't be ruled out after midnight near KAVL and the SC sites; S to SE PBL flow will serve as weak forcing. Restrictions are likely to develop around/after 12z as that flow replenishes sfc moisture and instability is realized, even if only as stratocu initially. Deep convection is possible as soon as mid-morning but more likely in the afternoon nearer axis of synoptic shortwave. Hence precip impacts are handled with PROB30s in the morning and TEMPO TSRA in the aftn. Any TSRA will be capable of torrential rain and so did not shy away from IFR vsby/cigs therein. Winds generally will remain southerly.

Outlook: Enhanced moisture will combine with a weak/stalled front through early next week, resulting in a period of active/mainly diurnal convective weather each day. There will also be the potential for restrictions associated with widespread fog and/or low clouds each morning.

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

Full Color Weather Map

Link to Loop


Other links: GEOS-West     Contential US     Full GOES-East

Greer, SC,