Area Forecast Discussion
Issued by NWS Houston/Galveston, TX
Issued by NWS Houston/Galveston, 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
004 FXUS64 KHGX 132009 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 309 PM CDT Mon May 13 2024 ...New SHORT TERM, LONG TERM, MARINE, HYDROLOGY... .SHORT TERM... (This evening through Tuesday Night) Issued at 304 PM CDT Mon May 13 2024 A very active afternoon with scattered to numerous strong to severe thunderstorms across portions of Southeast TX. The forecast for this afternoon and evening remains on track. Current mesoanalysis show a favorable environment with increasing PVA and strengthening upper jet over our region. The interaction of passing shortwaves aloft along with different surface boundaries (quasi-stationary warm front and sea-breeze/coastal boundary) will continue to be the main focus for convection over the next several hours. Surrounding soundings and sfc obs show steep mid-level lapse rates (~ 7 C/km), MUCAPE at/greater than 4,500 J/kg with 0-6km bulk shear around 40 to 50 knots, sfc dewpoints mainly in the 70s. These ingredients will be enough to support strong updrafts along the boundary (-ies). With decent instability in the hail growth zone, and wet bulb zero height around 11 kft and EBWD around 50 knots, large hail up to around 2 inches will continue to be the main severe threat this afternoon. As the main stalled boundary pushes southeastward into the coastal waters late this afternoon and evening, the threat will slowly transition to wind threat. Models show 0-3km helicity into the 100- 150 m2s-2 range and 0-1km helicity greater than 90-120 m2s-2 east of I-45, suggesting a secondary threat of damaging winds. Tornado threat is low given 0-1 km bulk shear near 5-10 knots. However, a few mesovortices/rotation cannot be ruled out, especially near boundaries this evening. A Severe Thunderstorm Watch is in effect for most of southeast TX until 8PM. Locally heavy rainfall is also expected; thus isolated flash flooding will be possible. Additional rainfall totals of 1 to 3 inches can be expected through late this evening with isolated higher amounts. Will continue with a Flood Watch for areas particularly north of I-10 through 7PM this evening. Storms should gradually taper off from west to east this evening as the boundary pushes offshore. Drier northerly winds will filter in, leaving us with dry conditions for the rest of the short-term period. Mostly sunny skies will lead to warmer conditions on Tuesday. Highs will generally be from the upper 80s to low 90s. JM && .LONG TERM... (Wednesday through next Sunday) Issued at 304 PM CDT Mon May 13 2024 A brief period of ridging aloft will keep things on the quiet-side on Wednesday behind the departing upper level trough that brought strong storms/heavy rain earlier in the week. With 850mb temperatures in the 90th percentile along with drier air in place (PW values less than 1"), we`ll see temperatures reach the upper 80s/low 90s. This quiet period will be the calm before the storm so to speak as we`ll have another upper level trough approaching from the southwestern CONUS. On Thursday, the upper level trough will be around the Four Corners region and will send out a few shortwaves out ahead of it. Surface low pressure is induced out in West TX on early Thursday, which places us in the warm sector. There will be an abundance of instability in place along with deep moisture (PW values greater than 2") in addition to some decent deep layer shear. As a result, widespread showers and thunderstorms are expected on Thursday as a shortwave pushes through. Another round of storms is in the cards for Friday as the trough pushes through along with a weak boundary. WPC already has most of Southeast TX in a slight risk of excessive rainfall (level 2 out of 4) on Thursday and areas around/east of I-45 in a marginal risk of excessive rainfall (level 1 out of 4) for Friday, so be on the lookout for locally heavy rainfall at the end of the work week. The highest of the rainfall totals between Thursday/Friday as of right now are anticipated to occur north of I-10 especially in the Piney Woods area...this is unfortunately the area that has seen the bulk of the rainfall recently. Soils remain fairly saturated up there, so quick responses along area rivers/creeks/bayous are possible as rainfall may quickly become runoff. Rain chances linger into Saturday before clearing out as drier air filters in along with surface high pressure. Ridging aloft builds in towards the latter half of the weekend and into early next week leading to a warming trend. Temperatures are expected to reach the low 90s on Sunday and these will continue into early next week. As far as temperatures for earlier in the week, with the rainfall expected on Thursday and Friday, expecting highs in the low to mid 80s. Low temperatures will generally be in the upper 60s to low 70s throughout the long term period, but there is an upward trend going into early next week towards the low to mid 70s. Batiste && .AVIATION... (18Z TAF Issuance) Issued at 1248 PM CDT Mon May 13 2024 An active afternoon and evening with strong to severe thunderstorms expected near/around the terminals. Thunderstorms will continue to develop and move eastward through early this evening. The best potential for severe thunderstorms will be for terminals south of CXO, though an isolated strong storm or two cannot be ruled out near/around CLL/UTS terminals. Large hail and damaging winds are the main threats. Gusty erratic winds and reduced visibility can be expected with any strong storms. Conditions should gradually improve late this evening. Benign aviation conditions are expected on Tuesday with northwest to north winds around 5 to 10 knots. JM && .MARINE... Issued at 304 PM CDT Mon May 13 2024 Light to occasionally moderate onshore flow will persist throughout most of the day along with seas in the 4 to 6 foot range. The main story for today though will be a line of strong to severe storms pushing off the coast in the early evening hours. These storms may bring strong wind gusts, heavy rain, and hail. A brief period of offshore flow is expected behind these storms. Offshore flow will prevail through most of Tuesday before transitioning back to onshore flow on Tuesday night. Wind speeds begin to increase late Wednesday and will likely prompt the issuance of caution flags. The elevated winds persist into Thursday as we get our next round of showers/storms and this will likely be followed by another round on Friday as well. Winds become a bit lighter heading into the weekend, but remain generally in an onshore direction. Batiste && .HYDROLOGY... Issued at 304 PM CDT Mon May 13 2024 A Flood Watch remains in effect through 7pm Monday evening for portions of the Piney Woods and the Brazos Valley. A line of strong to severe storms will push through Southeast TX this afternoon/evening. Soils in the watch area already fairly saturated from last week`s heavy rain events. This means that heavy rainfall will likely become runoff quickly leading to additional responses along area rivers/creeks/bayous. Flash flooding is also a possibility in these locations. Expecting 1-3" of rainfall with isolated higher amounts today. Minor to major river flooding continues for parts of Southeast Texas, particularly along portions of the Trinity and Brazos rivers. The following river points are either currently in flood stage or are forecast to reach flood stage (as of Monday afternoon): - Trinity River (Liberty): Major Flood Stage - Navasota River (Normangee): Major Flood Stage (forecast) - Trinity River (Crockett): Moderate Flood Stage - Trinity River (Riverside): Moderate Flood Stage - Trinity River (Moss Bluff): Moderate Flood Stage - Brazos River (West Columbia): Moderate Flood Stage - Trinity River (Goodrich): Moderate Flood Stage (forecast) - Brazos River (Rosharon): Minor Flood Stage - Brazos River (Sugar Land): Minor Flood Stage - Long King Creek (Livingston): Minor Flood Stage - Menard Creek (Rye): Minor Flood Stage (forecast) Remember to heed any instructions from your local officials and to never travel through ANY flooded areas or roadways. TURN AROUND, DON`T DROWN. Please monitor updated forecasts via the NWS AHPS website and/or the new NWS NWPS webpage (https://water.noaa.gov/) as the river flood threat continues. The next rounds of heavy rain are expected on Thursday/Friday, so be sure to stay up to date on the latest forecast information. Batiste && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 64 87 64 89 / 20 0 0 0 Houston (IAH) 68 90 66 90 / 60 0 0 0 Galveston (GLS) 72 85 74 83 / 60 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Flood Watch until 7 PM CDT this evening for TXZ163-164-176>179- 196-198>200. GM...Small Craft Should Exercise Caution until 7 PM CDT this evening for GMZ350-355-370-375. && $$ SHORT TERM...JM LONG TERM....Batiste AVIATION...JM MARINE...Batiste