Area Forecast Discussion
Issued by NWS Houston/Galveston, TXVersions: 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
000 FXUS64 KHGX 290018 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 718 PM CDT Wed Apr 28 2021 .AVIATION [00Z TAF Issuance]... MVFR ceilings expected tonight. Winds are gusty, but should subside overnight. A few scattered showers ahead of a frontal passage beginning at ~06Z for our northernmost sites as the front slowly drifts further south through tomorrow. Afternoon thunderstorms possible due to daytime heating along the frontal boundary, so put in VCTS for some sites. KBL && .PREV DISCUSSION /Issued 412 PM CDT Wed Apr 28 2021/... .SHORT TERM [Through Thursday Night]... A moderate to strong onshore flow will persist tonight. Cloud cover and mixing from winds will keep MinT values on the warm side and temperatures will struggle to fall below 70 degrees with most locations in the mid to lower 70`s. As moisture deepens below weak capping in the 850-700 mb layer, a few showers will be possible, especially over the western and northwest parts of the CWA. Low pressure will move into eastern OK overnight with a cold front extending from the low into Central TX. The front will trigger a line of showers and thunderstorms across Central TX and this line will inch its way toward SE TX late tonight and Thursday. have leaned toward the global models and TT WRF for the wind shift on Thursday with the front reaching a Trinity to Columbus line by late Thursday afternoon. Fcst soundings look rather impressive tomorrow aftn with PW values near 2.00 inches and K index values in the upper 30`s. CAPE values are modest with values between 700-1400 J/Kg and LI`s only around -3, but capping looks weak and there should be enough instability to generate thunderstorms by afternoon. Some of the storms could be strong with the stronger storms producing hail and gusty winds. SPC has placed the NE half of the region in a Marginal Risk on Thursday. The front will inch it`s way toward the coast Thursday Night with a narrow band of showers and storms along and ahead of the wind shift. Behind the front, there looks like there could be enough isentropic upglide to produce some elevated storms. MinT values will trend a bit cooler especially over the NW zones but likely remain warm and humid ahead of the front over the coastal counties. Will allow the Wind Advisory to expire at 00z and winds will probably remain a bit gusty through 03z but sustained winds will fall below 25 mph. Will let the Coastal Flood Advisory expire as well. The area is going into low tide and with tide departures only about a foot above normal, water levels should remain below 3 feet and little to no impact is expected. Have extended the Rip Current Statement through tomorrow as moderate to strong onshore winds remain favorable to produce strong rip currents. 43 .LONG TERM [Friday through Wednesday]... A rather wet weather pattern is expected for much of the first half of the long term period. To start, isolated to scattered showers and thunderstorms will continue to develop across portions of Southeast TX on Friday as the weakening frontal boundary along with ample low level moisture (PWs of 1.8 to 2.2 inches) shifts slightly north (more inland). There is some transition on Friday afternoon into early Saturday, where a coastal trough emerges and eventually a surface low builds across the Southern TX coasts Friday night into Saturday. Meanwhile, an cut-off upper low located in the general area of northern Mexico will shift further south southeastward into the north central regions of Mexico Friday into Saturday. This could put us under the influence of weak ridging, however, models show a few disturbances moving along the base of the low and into Southeast TX and could thus weaken the overall effect of the ridging for us...and would then support our chances for ongoing shower and thunderstorm activity. WPC Day Three ERO has continued the Marginal Risk for most of Southeast Texas for Friday. On Saturday, Southeast TX should be on the eastern peripheral of the upper low and in an area of stronger winds aloft while the surface coastal low moves northeastward into the Central TX coasts and further entrain ample Gulf moisture across the CWA. This along with the unstable airmass, would likely mean that rainfall activity will continue across the CWA for much of the day. Saturday night into Sunday, the low will weaken but continues eastward and across Southeast TX in response to an upper level trough moving into and amplifying along Western CONUS and the Rockies, again maintaining the potential for rainfall. Depending on how much rain we actually get Thursday and Friday, locally heavy rainfall could cause a few minor flooding issues in area where the soil is a bit more saturated this weekend. Activity will ebb Sunday night into Monday as all weather features finally shift to our east. Another chance for showers and thunderstorms may occur Tuesday evening into Wednesday with the next cold front, but because it is near the end of our forecast period...have stayed on the lower side (10-20%) of PoPs. 24 .MARINE... Small Craft Advisory will continue for the bays and Gulf waters through late tonight as winds and elevated seas continue. A Coastal Flood Advisory remains in effect for the Upper TX coast until 6 PM this evening and the Rip Current Risk remains in effect through Thursday evening. Winds will relax overnight into Friday morning. A cold front is scheduled to move into SE TX thursday afternoon. This boundary is forecast to move just off the coast by early Thurs night and bring with it scattered showers/isolated thunderstorms. Light N to NE winds can be expected Friday afternoon into Saturday morning and then turn SE Saturday afternoon/evening as a strong low pressure system tracks in from the west. As this system moves across and out of the region, expect periods of showers and thunderstorms throughout the weekend. Conditions improve Monday as this features shifts east and away from our region. 24 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 71 81 66 77 62 / 40 70 40 40 30 Houston (IAH) 72 85 70 78 64 / 10 50 40 50 30 Galveston (GLS) 73 80 71 78 69 / 10 20 40 40 20 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...High Rip Current Risk through Thursday evening for the following zones: Bolivar Peninsula...Brazoria Islands...Galveston Island...Matagorda Islands. GM...Small Craft Advisory until 4 AM CDT Thursday for the following zones: Coastal waters from Freeport to Matagorda Ship Channel TX out 20 NM...Coastal waters from High Island to Freeport TX out 20 NM...Galveston Bay...Matagorda Bay...Waters from Freeport to Matagorda Ship Channel TX from 20 to 60 NM...Waters from High Island to Freeport TX from 20 to 60 NM. && $$
