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
970 FXUS62 KGSP 061723 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 123 PM EDT Thu Jun 6 2024 .SYNOPSIS... Scattered showers and thunderstorms will develop this afternoon and linger into the evening. Dry Canadian air will mix across the area Friday and persist into the weekend. A chance of thunderstorms returns to the region Sunday, before deeply dry air builds back in Monday though Tuesday. && .NEAR TERM /THROUGH TONIGHT/... As of 120 PM Thursday: Convection developing across the area at this time, ahead of a short wave and cold front. Latest guidance showing better chance across NC than NE GA or the Upstate. Still expect scattered convection across NE GA and the Upstate, so basically tweaking PoP to show this scenario. Meso analysis shows DCAPE has not increased as quickly as 12Z soundings would have suggested. Still, a couple of severe storms with damaging winds are possible. Otherwise, a deep negatively tilted trough over the Midwest is forecast to slide into the Great Lakes region today. The Southern Appalachians will remain on the southern periphery of forcing for ascent within the base of the trough. Subtle height falls are still expected to overspread the area, however, in advance of a surface cold front dropping out of the Ohio Valley. The main focus will be for another round of convection this afternoon, which could be more robust compared to what we`ve seen the last several days. Compressional warming ahead of the front along with warming low- level temperatures will support afternoon highs climbing into the mid to upper 80s. Resulting insolation couple with upper 60s to low 70s dewpoints will yield 2000-3000 J/kg of surface-based CAPE. Increasing flow within the base of the trough in concert with a low-level jet translating across the area will also contribute 20-30kts of deep-layer vertical wind shear. Limited downdraft CAPE and modest lapse rates within a moist environment will limit the magnitude of any severe threat, but given the enhanced flow and shear several severe storms capable of locally damaging winds will be possible. This will especially be true for any multicell clusters/linear segments that can become organized along a composite cold pool. Near storm forecast soundings also depict weak low-level hodograph curvature as the low-level jet helps to elongate the wind fields. While not overly impressive by any means, 0-1km SRH nearing 100 m2/s2 could support a brief/transient circulation or two, which has been picked up on by several of the CAMs with brief updraft helicity streaks mainly along and south of I-85. Thus, a brief tornado cannot be completely discounted. A few storms may linger into the early evening hours, but will remain progressive ahead of the impending front and should push out of the area by or shortly after sunset. Thereafter, the cold front is expected to move through the area overnight with much drier air advecting into the region in its wake. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 1255 AM Thursday...The short range period remains dry as deep nw/ly flow commences while a subTrop high shifts east across the srn Plains. This pattern will support a Canadian sfc high building south bringing lowering column moisture to the FA. Cooler temps are associated with this high as well, but downsloping h9-h8 flow will modify the airmass warmer and allow for max temps arnd normal levels Fri and Sat. Along with increasing subsidence, the llvls will dry out with the downsloping and make for dry afternoons with RH values dropping into the 30 percent range each day. Not much cloud cover outside of Ci Fri and lowering clouds aloft by Sat afternoon. Mins will fall to normal levels Thu night and abt 5 degrees cooler Sat night with no great fog threat each morning. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 115 AM Thursday...No sigfnt changes were made to the ext range fcst outside of lowering PoPs a bit Sun and Mon. The atmos becomes more dynamic Sat night with a stg embedded h5 s/w traversing the flow thru Sun morning. Low level moisture will be limited and only expect increasing mlvl cloud cover thru mid day. A cold front makes it to the NC mtns Sun afternoon, but with little upper support, expect the best precip chances across the NC mtn/fthills due to added mech lift. Decent agreement is had in the guidance with the progression of the front as it tracks across the FA during the evening and overnight. The atmos remains quite stable ahead of the front, but increasing sfc convg could spawn a few general tstms east of the mtns by late afternoon Sun. Another dry Canadian airmass mixes in Mon and likely lingers into Tue, which will make for low RH values during the afternoon periods. The next chance of precip will be Wed as moist return flow ensues. Temps will pretty much remain arnd normal levels each day. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... At KCLT and elsewhere: Convection beginning to develop across the area ahead of a cold front. CAM guidance shows better chance over the NC sites than the SC sites. Have kept a TEMPO in all areas given the radar presentation but toned down some of the impacts except for KCLT where CAMs show the highest chance. Gusty SW to WSW winds continue ahead of the front with a wind shift to NW but diminishing wind behind the front. Drier air moves in behind the front as well limiting the chance of restrictions overnight. Dry conditions with NW wind continues Friday. KAVL will see NNW wind overnight with gusts redeveloping on Friday. Outlook: High pressure will linger through Saturday before another frontal system moves in on Sunday possibly lingering into Monday. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...SBK NEAR TERM...RWH/TW SHORT TERM...SBK LONG TERM...SBK AVIATION...RWH