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 122337 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 537 PM CST Tue Jan 12 2021 .AVIATION [00Z TAF Issuance]... Latest radar imagery showing a few isolated showers pushing northward in the vicinity of UTS and CLL, and thus have started the current TAF package with VCSH wording at these sites. Otherwise, not expecting any precipitation impacts overnight with cigs/vis remaining within VFR thresholds as the current ~10kft deck gradually clears by Wednesday morning. Forecast soundings at LBX indicate the potential for some fog overnight, though anything that does develop should be fairly shallow given the much drier air aloft. Tomorrow, a southwestward shift of surface winds is expected as an area of surface high pressure drifts to the east. Winds should generally remain around 5-10 knots. Cady && .PREV DISCUSSION... /ISSUED 233 PM CST Tue Jan 12 2021/ SHORT TERM [Tonight through Wednesday Night]... Some rain/showers (even a little bit of frozen precip too!) along with isolated thunderstorms have developed today in association with some weak embedded impulses ahead of the next shortwave/storm system. This system is responsible for today`s increase in cloud cover, and these extra clouds will help to keep our temperatures steady for most of the area during the remaining afternoon hours. As the shortwave moves further eastward and eventually across and through our area later today and on through tonight, cannot totally rule out the chance of some more precip development as indicated by some models. Will carry low rain chances with this system as most of the activity that will be seen on radar should evaporate before reaching the ground. Clouds should be clearing out from west to east very late tonight through tomorrow morning, and have overnight low temperatures mainly in the low to mid 30s inland and in the low to mid 40s at the coast. Abundant sunshine tomorrow and mainly light southwest winds should allow afternoon high temperatures to get close to 60 degrees, something much of the area has not seen since last Thursday. Another cool night can be expected on Wednesday night with lows ranging from the mid to upper 30s well inland to the lower 50s at the coast. 42 LONG TERM [Thursday Through Tuesday]... On Thursday, a sharp digging trough located over northern CONUS will deepen and a surface cold front will push its way across our CWA. No precipitation is expected still since forecast soundings indicate a strong capping inversion, low PWATS, and no upper-level support. All the above will suppress any precip over land, however some showers could form over our coastal waters. The main impact expected from this frontal passage is slightly stronger winds and CAA which will help keep temperatures cool with no significant warming expected over the next few days. Sunday looks like it will be the next best day for rain chances with another surface cold front moving through. Once again, the GFS and Canadian are being more aggressive with this next front. They both hint towards a low developing over Central Mexico and emerging as a coastal low near Brownsville and then strengthening rapidly over the Gulf. The GFS places our CWA underneath the outer fringes of the left entrance region of a jet streak which is not entirely favorable for upper-level support. However, theta-e advection, higher PWATS (0.7-1.0 inches), no low-level capping inversion, and strong PVA will still provide enough lift and support for a decent front and precip across our CWA. The ECMWF also shows this coastal low near Brownsville, however the right entrance jet streak is well over the Central Gulf and keeping most of the precip offshore. Finally, by Tuesday, the ECMWF is hinting that residual moisture from Sunday`s frontal passage as well as another PVA lobe/shortwave moving across our region will kick up enough instability by Tuesday morning and bring another surface cold front and heavy precip to SE TX. The GFS is also hinting at a front, but places it further west and less intense, not impacting our CWA. Something to monitor for sure as it looks like mid-week next week could bring another chance for rain. KBL MARINE... Currently, NE winds will become N overnight and then gradually become NW by Wednesday ahead of the next frontal passage. By Wednesday night, winds gradually switch to the SW and strengthen to near Exercise Caution criteria. The best rain chances with this system remain well offshore in our Gulf Waters 20-60 miles out. After the front passes on Thursday, winds switch quickly to offshore winds and strengthen further and Small Craft Advisory conditions are likely. Winds will remain strong and offshore through Friday night and early Saturday before winds and seas subside. With strong offshore winds on Friday, a low water advisory for our bays could be possible. Finally, our next front is expected to push through sometime on Sunday and bring with it rain and thunderstorm chances. KBL && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 49 32 58 38 66 / 10 10 0 0 0 Houston (IAH) 51 35 60 40 69 / 10 10 0 0 0 Galveston (GLS) 50 44 57 51 66 / 10 10 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$
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