Area Forecast Discussion
Issued by NWS San Angelo, TX
Issued by NWS San Angelo, TX
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
432 FXUS64 KSJT 021918 AFDSJT Area Forecast Discussion National Weather Service San Angelo TX 218 PM CDT Thu May 2 2024 ...New SHORT TERM... .SHORT TERM... (This evening through Friday) Issued at 217 PM CDT Thu May 2 2024 ...Severe weather possible today and tomorrow... A surface low is currently located just to our northwest, with a dry line across out western most counties and a cold front moving in from the north. Storms are expected to form later this afternoon and evening near the low, where the dry line and front interact. Most models have storms developing in the Big Country starting around 4 this afternoon and continuing overnight. We are seeing some cumulus development in Nolan County, which could be a precursor for thunderstorms in the next couple of hours. The majority of models show most of the activity staying in the Big Country, Heartland, and northern Concho Valley, with a few storms finding their way into the our southern counties. Instability will be very high this afternoon (4000+ J/Kg possible) and wind shear values will be sufficient for severe development. With the instability as high as it is, storms could very quickly become severe once they develop and outflow boundary`s could trigger new storms. The main threat today will be large hail (2+ inches), but damaging winds and an isolated tornado are also possible. Localized flooding will also be possible with these storms, as rain amounts could exceed 2 inches under isolated storms. Tomorrow will be slightly cooler for the Big Country, as the cold front keeps winds from the north and east for the start of Friday. Winds will return back to the southeast for much of the area and the dry line will retreat westward again, leaving us with dewpoints in the 60s and 70s. CAPE values could be in excess of 3000 J/Kg by the late afternoon. Weak convergence on any residual boundaries and an upper level disturbance aloft could be enough to produce storms in the late afternoon. CAMs are differing on coverage for tomorrow. The HRRR is bringing much more widespread activity, with storms developing to the west and moving into the area. With the large instability and sufficient shear, any storm that develops could produce very large hail, strong winds, and possibly a tornado.&& .LONG TERM... (Friday through Wednesday) Issued at 343 AM CDT Thu May 2 2024 Friday could see another round of dryline development. With our area in continued southwest flow aloft and on the fringe of the southern stream jet, guidance is indicating the potential for a shortwave to pass overhead during the afternoon hours. This would likely provide enough upper level support to see development off of a quasi-dryline likely somewhere near our western CWA border. Southeasterly surface winds through the day will help to moisten the boundary layer across the area leading to MLCAPE values between 2500-3500 J/kg. Shear will be similar to previous days in the 25-35 kt range with mid level lapse rates right around 8 deg C/km. SPC has the Day 2 Marginal ending just north of our area in the Caprock, if guidance continues to trend the way it has with the shortwave passage, would not be surprised if this is extended further south in future updates. The main threats would likely be large hail and damaging winds. Current indications are that these storms would move off to the east fairly quickly with the threat tapering off after midnight. By Saturday, a frontal boundary is expected to stall just north of our area. Storms will be possible along the front earlier in the day, keeping rain/storm chances in play for northern areas of the Big Country Saturday morning. However, as the boundary layer heats up and destabilizes through the day, more diurnal activity is expected to develop across the area with yet another potential shortwave passing overhead. Later in the day, an easterly low level jet is expected to develop, helping shower and storm activity to become more widespread, potentially developing into an MCS type feature. With ample instability in place and steep lapse rates, some storms could become severe, especially across the Big Country and western Concho Valley where the Day 3 Marginal Risk for severe storms is located. As activity becomes more widespread Saturday afternoon through Sunday morning, this looks to be the best timeframe to see heavy rainfall leading to flash flooding. As such, WPC has put the Big Country, Concho Valley, and Heartland in their Slight Risk (Level 2 of 4) for excessive rainfall with the rest of the area in Marginal (Level 1 of 4). The highest rainfall totals will likely be in the Big Country, closer to the frontal boundary. With the weak frontal boundary still in the region for Sunday and southwest flow continuing aloft, we will see continued chances for showers and storms through the day before coming to an end overnight into Monday morning. High temperatures through the weekend will generally stay in the upper 70s to 80s. A large upper trough is expected to move north of our area during the day on Monday. As a dryline pushes east into our area during the day, upper level support may be strong enough to warrant a chance of showers and storms across our northeastern counties between 18-00Z. Better chances will stay well to our north though, closer to the negatively tilted trough axis. Behind the dryline, skies will begin to clear and winds will pick up out of the west. This dry, downsloping air will help to warm temperatures into the lower 90s for the Concho Valley and Northern Edwards Plateau. Elsewhere should see highs in the mid to upper 80s. The dryline is overall expected to make little retreat to the west overnight and will push even further east on Tuesday and Wednesday. This should keep our area dry and allow for temperatures to reach well above average into the 90s, even the mid and upper 90s for areas south of the I-20 corridor. CPC has our area highlighted in their 8-14 day Slight Risk for Excessive Heat for May 9-11 so unfortunately it looks like the heat will be sticking around through the end of next week. && .AVIATION... (18Z TAFS) Issued at 1232 PM CDT Thu May 2 2024 Skies are clearing from west to east, lifting MVFR CIGs to VFR over the next hour or so. Storms are possible later this afternoon and overnight. Exact location of the storms is uncertain, KABI has the best chance of seeing storms this evening, but the other sites could have a nearby thunderstorm as well. Gusty winds, lighting, and hail will likely accompany these storms. Low clouds will move in overnight, dropping CIGs to MVFR and IFR. && .PRELIMINARY POINT TEMPS/POPS... Abilene 63 82 64 81 / 40 40 40 70 San Angelo 64 90 64 87 / 10 40 30 60 Junction 67 90 66 89 / 20 30 20 40 Brownwood 63 83 66 81 / 50 30 40 60 Sweetwater 62 84 63 80 / 20 40 40 80 Ozona 66 89 64 84 / 10 40 30 40 Brady 64 84 66 83 / 30 30 30 50 && .SJT WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...AP LONG TERM....50 AVIATION...AP