Marine Weather and Tide Forecast for Riverside, TX

FXUS64 KHGX 210553 AFDHGX

Area Forecast Discussion National Weather Service Houston/Galveston TX 1153 PM CST Mon Jan 20 2025

New AVIATION

SHORT TERM
(This evening through Tuesday Night)
Issued at 303 PM CST Mon Jan 20 2025

*** HISTORIC WINTER STORM TO IMPACT SE TEXAS ***

KEY MESSAGES:

1) Deteriorating conditions are expected overnight with moderate to heavy mixed precipitation tomorrow morning and early afternoon.

2) Snow totals of 4-6" along and south of the I-10 corridor, 1-3" north of the I-10 corridor and SW of the Houston Metro. Higher amounts are possible in the strongest bands. Ice accumulations of up to 0.1" possible.

3) Extremely cold temperatures are expected on Tuesday night, with lows near or below 20 degrees.

4) Travel will be extremely hazardous and not possible at times.
Driving should be avoided in impacted areas until conditions become safer.

Confidence has continued to increase in the prospect of a historic winter storm to impact the area overnight tonight into tomorrow afternoon. Based on the current forecast, this will be the most significant winter storm the Greater Houston area has experienced since at least 1960. This is a highly unusual event for our region that will produce very hazardous travel conditions throughout the course of the day tomorrow and into the early parts of Wednesday. As such, it must be stressed that travel should be avoided at all costs until conditions become safer.

Synoptic models continue to remain on track with their depiction of a weak coastal low/trough in the Western Gulf that will continue to push northeastward tonight and into tomorrow. As this occurs, an amplified midlevel trough will push into the Southern Plains by tomorrow morning. Global models also placing SE TX within the right entrance region of a strong jet streak, thereby providing favorable conditions for vertical ascent/upper level divergence as the system approaches the SE TX coast.

Latest guidance indicates the onset of precipitation as early as 6 PM this evening across parts of the northern zones. Initial light precipitation is expected to fall as cold rain or a mix of rain, sleet, and snow as temperatures cool below freezing over the course of the overnight period. This could amount to some measurable snow and/or sleet before midnight, particularly across locations to the north of the I-10 corridor.

More significant precipitation will begin after midnight and likely peak between approximately 6 AM and Noon tomorrow as the aforementioned low pressure system pushes closer to the coast.
Confidence remains high that most of this precipitation will fall as snow. However, we could see periods of a wintry mix depending on relatively small fluctuations in the temperature profile over the course of the event. Areas SW of the Houston Metro, where forecast soundings indicate a more robust layer of warm air aloft, may pick up some freezing rain during this time period with total ice accumulations between a hundredth and a tenth of an inch.

Between today's suite of global model guidance, high resolution models, and probabilistic ensemble guidance, our forecast snowfall totals have experienced a slight shift to the south but otherwise have remained generally on track from the past few forecast packages. The heaviest snowfall continues to remain concentrated along and south of the I-10 corridor, particularly the southern portion of Metro Houston, Galveston Bay area, and the Galveston Island area. Widespread totals of 4-6" of snowfall are expected to fall in these locations, with the rest of SE Texas likely to see 1-3" of snowfall. Mesoscale models continue to show the potential of a few heavier bands of snow, and as such we could see some localized amounts higher than 6 inches. Winter precipitation should generally clear from north to south, with precipitation ending during the early afternoon hours. The temperature forecast tomorrow is complicated, and will be tied to the timing and location of any snowfall. Most locations will have the potential to break above freezing, if only slightly, but there's a chance some areas may remain at or below freezing for the entire day. More clarity on this may not arrive until we are well into the event tomorrow.

Forecast snow totals certainly stand out in a historical context.
While we will not break the all-time snowfall record for Houston (14" in 1895), a total of higher than 3" would surpass the 1960 winter storm as the second highest snowfall total in recorded history for Houston. As the forecast stands, this should be considered a generational winter storm event and its impacts should be taken seriously. Travel overnight and tomorrow will be extremely hazardous if not impossible for much of the area, and travel is highly discouraged. Roads will become slick and difficult to drive on, with icing possible on elevated roadways and bridges.

We continue to also anticipate a very cold morning on Wednesday, with the combined impacts of cold advection and a lingering snowpack bringing overnight lows to near or below 20 inland and in the mid 20s along the immediate coast. Low temperatures will be subject to the location of where the heaviest snow falls, and possible upward/downward adjustments in the forecast will be required once a better picture of the snowpack emerges. As such, we have maintained the Extreme Cold Watch for now, as some areas still are poised to reach wind chills of 10-15 degrees during the early part of Wednesday. The likely locations of the coldest lows/wind chills should emerge tomorrow afternoon. Regardless, these cold temperatures will allow for accumulated precipitation to remain on surfaces/roadways and also may result in refreezing of any lingering liquid.

Preparations for this historic storm should be finalized as soon as possible. Be prepared to potentially need to stay where you are throughout the day on Tuesday and into early Wednesday as travel conditions may not be safe. Be sure to consider any final actions needed to protect the "4 Ps" - People, Plants, Pets, and Pipes.

Cady
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