Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
790 FXUS62 KGSP 121947 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 247 PM EST Tue Nov 12 2024 .SYNOPSIS... Dry high pressure remains in place through Wednesday. Clouds and precipitation arriving late Wednesday night will make for a very damp and chilly Thursday. Dry weather a warming trend expected Friday through the weekend. Dry and warm conditions continue early next week. && .NEAR TERM /THROUGH WEDNESDAY/... As of 212 PM EST Tuesday...Lots of bright sunshine with only a few cirrus streaks moving overhead, as seen in the satellite imagery this afternoon. The forecast appears to be mostly on track, but some locations were running a bit warmer and drier than expected, so a few trend changes were made. High pressure will take up residence over Quebec tonight, supported by a slow-moving full-latitude mid/upper ridge, whose axis approaches from the west tonight and moves overhead Wednesday. The air mass building down from the high to the north tonight will be much cooler and drier than what we have had lately. Guidance finally shows low temps tonight dropping down close to seasonal norms. This could bring some freezing temps to the mountains and some frost potential to the nrn foothills and NW Piedmont, but readers should note that GSP has ended our Frost/Freeze program for the season. Thus, no advisories will be issued. The sfc high will remain in a good position to ridge down the east side of the mtns as a dry wedge on Wednesday. The resulting cool northeast sfc flow should keep temps about five degrees below normal for highs, even with what should be plenty of sun, at least early in the day. High clouds will thicken from the west in the afternoon as a conveyor belt of moisture approaches ahead of the next system. Present indications are that the leading edge of any precip will not reach the forecast area from the west before sunset. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... As of 235 PM Tue: A cold air damming high will be in place to start the period. A short wave crosses the area with increasingly moist southerly flow ahead of the associated approaching cold front. While initially dry, the atmosphere moistens quickly in the strong southerly flow. The increasing moisture, combined with the synoptic forcing from the short wave and isentropic lift, will lead to increasing precip chances, initially across the mountains Wednesday night, then across the entire area by Thursday morning. The front moves relatively quickly across the area with precip ending by late in the day or early in the evening Thursday. Dry high pressure with decreasing clouds expected for Friday. Thermal profiles show a cold and dry air mass in place along and near the Blue Ridge at precip onset. Wet bulb temps look to be near but above freezing, so precip should be rain even in these areas. However, the cold air just above the surface and under the strengthening warm nose, will likely lead to a brief period of sleet at precip onset. This sleet could fall across a large portion of the area before quickly transitioning to rain. This is a common occurrence in these types of situations with no more than a "gee whiz" amount of sleet. Breezy winds are also expected Thursday with the CAD in place, then again on Friday behind the cold front. Lows Wednesday night will be a few degrees above normal. Highs Thursday will have a typical CAD set up with temps 10 to 15 degrees below normal for all but the valleys near the TN border where near normal temps are expected. Lows Thursday night warm a few degrees across the mountains and cool slightly or remain nearly steady elsewhere. Highs Friday will be near to slightly below normal. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 210 AM Tue: Surface high pressure and warming temps expected for the weekend as an upper ridge builds over the eastern CONUS. A short wave dents the ridge Sunday night with a cold front moving across the Mid Atlantic Monday. The ridge rebuilds late Monday before a short wave moving up the ridge on Tuesday brings a weakening cold front toward the area from the west. The result is a dry forecast through the period with temps rising above normal through Monday then dropping a few degrees on Tuesday. && .AVIATION /20Z TUESDAY THROUGH SUNDAY/... At KCLT and elsewhere: VFR through the period at all terminals, with only some passing thin cirrus. Dry air should preclude fog formation in most places across the mtns tonight. Wind should be light N to NE this afternoon and into the overnight hours, but may pick up from the NE in the pre-dawn hours Wednesday as high pressure builds down from the north. Might see occasional gusts at some locations as we mix deeper after mid-morning as the pressure gradient improves. High clouds will begin to thicken Wednesday afternoon ahead of the next system. Outlook: A cold front will bring rain and restrictions to the terminals Wednesday night into Thursday. High pressure brings dry and VFR conditions back Friday into the weekend. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...RWH NEAR TERM...PM SHORT TERM...RWH LONG TERM...RWH AVIATION...PM