Sunrise 6:43 AM   Sunset 8:12 PM Moonrise 8:12 PM   Moonset 5:55 AM

  Print   HELP   Reset   Save   Recall

FXUS62 KGSP 241332 AFDGSP

Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 932 AM EDT Wed Apr 24 2024

SYNOPSIS
High pressure off the Southeast Coast will give way to a weak cold front moving down from the north today. The cold front should stall to our south tonight and Thursday as high pressure moves past to our north. The front will move back northward on Friday and wash out across our area, but giving us a cooler day because of clouds and showers. After that, expect a warming trend through the weekend as high pressure takes over.

NEAR TERM /THROUGH TONIGHT/
As of 929 AM EDT Wednesday: A weak cold front continues to approach the area from the west with a band of showers slowly pushing into the mountains along the Tennessee border. Large dewpoint depressions and considerable dry sub-cloud layer air will limit how much precipitation actually reaches the ground. Nonetheless, light rain is likely across the mountains with coverage waning to the east this afternoon owing to a lack of stronger forcing and deeper moisture. A few minor adjustments were made to the forecast, otherwise no major changes were needed.

Lowering cloud deck in association with the main frontal zone has pushed into the NC mountains and will begin to spew further south and east through the morning hours. Precip along the the boundary has reached the immediate TN border and will overspread portions of the mountains over the next few hours. Shortwave trough currently resides over the Great Lakes region with the attendant frontal boundary draped from the Great Lakes through the OH Valley and mid- MS Valley. With surface high pressure set up shop just offshore the Southeast Coast, weak southwesterly WAA will continue to filter into the CFWA, ahead of the front. Expect increased cloud cover east of the mountains by late morning into the early afternoon and overspreading a good chunk of the area. The frontal boundary is expected to sag south through the CFWA during peak heating, which will help to generate a few showers along the boundary east of the mountains. Coverage will be minimized due to the lack of forcing and moisture as the better DPVA will reside north of the area, in the vicinity of the parent low. CAMs still kick off some showers later in the afternoon and in the evening for the CLT Metro and eastern Upstate, which increases confidence enough to at least put a mentionable PoP in these zones. Afternoon highs will run near- normal, but could fluctuate by a few degrees depending on the extent of cloud cover along the boundary as it pushes through the CFWA. The boundary is expected to complete a full fropa by midnight tonight as a continental surface high settles over the Upper Great Lakes region and filters in a dry northerly wind behind the front. Cloud cover will gradually scour out from north to south overnight, with mostly clear skies for much of the area by daybreak Thursday. Overnight lows are forecasted to run at or a few ticks below normal for most locations.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
As of 303 AM Wednesday: A weak cold front should stall out to our south on Thursday as a surface high moving past to our north ridges down and gives as a pretty springtime day with temps a few degrees on the cool side of normal. On Thursday night, that high pressure center will move to the Hudson R Valley, in a decent position to function as a parent high to the formation of a cold air damming wedge across the fcst area. Meanwhile, the old front will start to lift back northward in response to the low pressure system wrapping up over the central Plains. The forecast becomes uncertain, though, because the all the players don't seem to be reading from the same script. The main problem might be the building mid/upper ridge axis overhead on Friday, which keeps the mid/upper forcing away to the west and minimizes the development and impact of isentropic lift at low/mid levels. The end result is a relatively low chance of precip, particularly east of the mtns where it would be needed to lock in a wedge air mass. Instead, we just end up with a slightly cooler day with some showers around, mainly over the mtns. If we get more precip than expected, then high temps will have to be cut down accordingly. Any precip that develops should diminish overnight on Friday night.

LONG TERM /SATURDAY THROUGH TUESDAY/
As of 227 AM Wednesday: Not much to get excited about out in the Medium Range. The upper pattern progression slows to a crawl over the weekend, keeping the axis of a mid/upper ridge over the area from the Appalachians to the East Coast, and all the energy lifting northeastward out of the upper troffing over the Plains off to our west through at least Monday. This pattern will support a surface high pressure center migrating from off the nrn Mid-Atlantic Coast on Saturday morning to a position off the Southeast Coast on Monday. While the high position is favorable for cold air damming on Saturday, once the sun comes up and warms the boundary layer, the static stability is no longer high enough and the low level flow veers around to the east and southeast. Expect a few ridgetop showers in the afternoon on Saturday, which will be included. There is some indication of a weak impulse coming in from the Atlantic to give us some shower activity on Sunday, but the chance of that is too remote to include just yet. Monday also looks basically dry. Instead, the main deal will be warming temps through the weekend and into the first half of next week, creeping upward a few degrees each day and ending up on the order of ten degrees above normal by Monday and Tuesday. Eventually, by Tuesday, the axis of the upper ridge goes positive and gets pushed off the East Coast as the deamplifying upper trof finally lifts out of the Plains and across the Great Lakes. This should push a dying cold front toward the region on Tuesday, possibly through the region Tuesday night, accounting for a chance of precip during that time period. We always look for severe storm possibilities with springtime frontal passages, but this one looks fairly unimpressive at this time. In fact, looking ahead a bit, the model blend barely makes a bump in the temps.

AVIATION /14Z WEDNESDAY THROUGH SUNDAY/
At KCLT and elsewhere: VFR conditions will prevail at all TAF sites through the forecast period. Cirrus continues to filter in across the area, while a lowering cloud deck begins to push across the NC mountains. Expect this cloud deck to thicken and overspread the region through the morning hours. Low VFR cigs are forecasted with this deck as a cold front approaches the terminals from the northwest during the day. With high pressure centered offshore the Southeast Coast, southwesterly winds will filter in ahead of the front with low-end gusts possible during peak heating.
Showers will accompany the boundary and the latest guidance are indicating slightly better coverage. Showers will come close to KAVL and decided to keep a PROB30 mention for showers during the mid- morning and early afternoon hours. Showers may develop along the boundary east of the mountains and could affect KCLT, KHKY, and the Upstate sites during peak heating, mainly after 18Z. Confidence is just high enough for a VCSH mention at KCLT as trends continue to support more shower development along the front as it slips through the area during the daytime period. Winds will shift to a northwesterly component at KAVL this morning and this wind shift will impact the rest of the terminals later in the afternoon and evening as winds toggle to a north-northwesterly direction and eventually northeasterly by the very end of the forecast period, behind the front with clouds slowly diminishing.

Outlook: Dry weather returns Thursday into this weekend, but this is subject to change as a warm front lifts north of the area by Saturday with possible restrictions.

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,