FXUS64 KHGX 102347 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 647 PM CDT Fri May 10 2024 ...New AVIATION... .SHORT TERM... (This evening through Saturday Night) Issued at 337 PM CDT Fri May 10 2024 Hope everyone has been able to enjoy the low dew points today as the high humidity gets turned back up starting tomorrow night as onshore flow begins again. Very weak ridging aloft will continue through tomorrow, but some shortwave passing through will keep partly to mostly cloudy skies in the forecast (and even when we do get breaks in the clouds, the hazy skies will continue thanks to the fires down in Mexico). Winds will turn from NE to E to ESE through the day on Saturday as the surface high pressure moves into the Central Gulf Coast. The onshore winds will lead to high moisture levels making their way back into SE Texas, and with that the chance for precipitation. While we likely won't see any showers during the daylight hours on Saturday, some isolated showers and storms may begin to move into the area from the west overnight Saturday night into Sunday morning. But more on this in the Long Term section below. Low temperatures tonight will be in the mid 60s north of Harris County, upper 60s to low 70s along the I-10 corridor, and then mid 70s along the immediate coast. High temperatures Saturday afternoon will be fairly close to normal with afternoon getting up into the mid to upper 80s. Low temperatures Saturday night will be a few degrees warmer compared to tonight thanks to the return of the onshore flow. Fowler && .LONG TERM... (Sunday through next Thursday) Issued at 337 PM CDT Fri May 10 2024 Chance of rain will increase Sunday as upper level disturbances embedded in the quasi zonal flow aloft move across Southeast TX while a warm front pushes north northeastward, instability increases, and a surge of moisture moves in from northwestern Gulf of Mexico. On Sunday morning, we could begin to have isolated to scattered shower and thunderstorm activity over most of the region, but we will have to see if the cap is going to limit development for us. As the day progresses however, storm coverage is expected to increase as the cap weakens, with areas north of I-10 possibly having widespread chances of rain for much of the afternoon into evening hours. Model guidance shows the surge of moisture carrying PWs between 1.8 to 2.1 inches moving across the region in the afternoon to evening as some vort maxes also push through. Moisture levels along the mid levels will also be high. Thus, periods of heavy rainfall, in particular over portions north of I-10, can be expected. WPC has placed a Slight Risk (threat level 2 out of 4) for excessive rainfall for much of Southeast TX, except the areas in and around Matagorda Bay, which is under a Marginal Risk (threat level 1 out of 4). Some storms could become strong at times and may produce strong gusty winds and hail. SPC currently has a Marginal Risk (threat level 1 out of 5) for severe thunderstorms. Shower and thunderstorm activity is expected to decrease Sunday night as we loose some moisture and instability and the cap tries to re-develop. However, periods of isolated to scattered activity will still be possible. Breezy conditions are possible Sunday evening into Monday morning as a low level jet develop over us. On Monday, a stormy weather pattern will emerge once again. Upper level disturbances will continue to move through as an upper level trough digs into the Southern Plains and a cold front makes its way across Central TX. Another surge of moisture from the Gulf will move into Southeast TX sometime mid morning to afternoon hours while the cap weakens/instability increases and several vort maxes move overhead. Model guidance/forecast soundings show CAPE values of 3000- 4500 J/kg over much of the region Monday afternoon and evening, with the highest values situated over areas north of the I-10 corridor. They also indicate SFC-6km shear values between 40-50 knots, PWs near 2.0 inches, steep mid level lapse rates, dewpoints in the mid 70s. Not to forget that this is all setting up just ahead of an approaching cold front, which is progged to move across the region sometime Monday night. Overall, the set up could support another day of heavy rainfall on occasion as well as strong thunderstorms capable of producing hail and strong winds. Although it is too soon to tell exactly where and when the stronger storms and heaviest rainfall will be on Sunday and Monday, the latest guidance favors areas north of I-10. It is also too soon to say how this rainfall will affect our ongoing river flooding, but please be aware that additional rises along creek, small streams and rivers will be possible. That being said, our estimated rainfall totals at this time from Sunday into Monday are generally 2-4 inches with isolated higher amounts over areas north of I-10 and 1-2 inches with isolated amounts elsewhere. Please continue to monitor the latest forecast and make sure to have multiple ways of receiving warnings. A respite can be expected on Tuesday and Tuesday night as drier air moves in behind the cold front. Some isolated showers could occur on Wednesday as moisture begins to move back into the region and a mid to upper level disturbance moves close to our western counties. On Thursday, scattered showers and thunderstorms will be back on the table as another series of disturbances move aloft along with a surge of low level moisture, good instability in place and a warm front moves over the region. Rain chances decrease sometime Thursday night into Friday morning as another cold front pushes across Southeast Texas. With respect to temperatures, the cloudy skies and rainfall will allow for high temperatures in the upper 60s to low 70s over areas north of I-10 and the low 70s elsewhere. The lows Sunday night into early Monday morning will be in the upper 60s to low 70s over areas north of I-10 and in the low to mid 70s elsewhere. Tuesday and Wednesday, the highs will increase into the mid to upper 80s and the lows will be generally in the mid to upper 60s inland and the low 70s along the immediate coasts. Highs could remain in the 80s on Thursday but exact values will depend on where and when the rain develops. 24 && .AVIATION... (00Z TAF Issuance) Issued at 641 PM CDT Fri May 10 2024 VFR conditions ongoing with VFR expected to prevail through the majority of the period. Very light patchy fog may develop during the overnight hours. The caveat would be if winds were able to become calm enough to allow for development. Have continued to withold this from the TAFs given the low probability of occurrence. Light easterly winds of less than 10 knots expected overnight, becoming easterly to southeasterly through Saturday. Clouds will begin to increase Saturday night as southerly winds draw moisture into SE Texas...CIGs may approach or reach MVFR levels around 20Z Saturday. && .MARINE... Issued at 337 PM CDT Fri May 10 2024 Moderate to occasionally strong northeast to east winds and seas of 3 to 6 feet will continue through Saturday. Caution flags are in place for the Gulf waters through Saturday evening, but may be upgraded to a Small Craft Advisory for Saturday morning. Moderate onshore flow is expected Sunday and Monday. A cold front will move into the coastal waters Monday night or early Tuesday morning and will result in variable winds on Tuesday. Onshore flow could return by Tuesday evening and continue through Thursday. Another cold front is expected to push across the region sometime Thursday night, resulting in moderate to strong offshore winds on Friday. Periods of showers and thunderstorms can be expected Sunday through Monday night, some could be strong at times. Another round of showers and storms can be expected on Thursday and Thursday night. 24 && .HYDROLOGY... Issued at 337 PM CDT Fri May 10 2024 Although there have been decreases in the water levels along the rivers, some will remain swollen for days (possibly weeks). Do NOT go around barricades and stay out of the floodwaters. Do NOT return to homes until officials deem that it is safe. River flooding continues for parts of Southeast Texas, particularly along portions of the Trinity river. The following river points are at Moderate or Major flood stage as of Thursday afternoon: - Trinity River (Liberty): Major Flood Stage - Trinity River (Moss Bluff): Moderate Flood Stage - Trinity River (Riverside): Moderate Flood Stage - Trinity River (Goodrich): Moderate Flood Stage Remember to heed any instructions from your local officials and to never travel through 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.  Also of note is that the downstream runoff from the previous rainfall will cause continued rises along the Brazos River through the end of the week. 24 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 65 83 67 79 / 0 10 20 80 Houston (IAH) 69 85 70 82 / 0 10 20 70 Galveston (GLS) 74 81 74 81 / 0 10 10 50 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...None. GM...Small Craft Should Exercise Caution until 7 PM CDT this evening for GMZ330. Small Craft Should Exercise Caution through Saturday evening for GMZ350-355-370-375. && $$ SHORT TERM...Adams LONG TERM....24 AVIATION...Fowler MARINE...24