Texas Fall-2015

[dhweather]

18Z GFS rolling in, wet

[gboudx]

From Steve McCauley:

Rain continues across the western half of north Texas with individual storms moving NNE but with the general rain area moving very slowly to the E.

The rain will gradually overspread all of the Metroplex tonight into the day Friday. Friday will be a washout with moderate to locally heavy rain throughout most of the day. 2 to 5 inches will be common across all of the Metroplex, but there should also be a band (50 miles wide) of "training storms" that will produce totals IN EXCESS OF 6 INCHES setting up somewhere over the Metroplex and immediately surrounding area. Forecasting where this band of potentially dangerous flooding will be is very difficult. It looks like it will set up across the SE half of the Metroplex - generally SE of a line from Greenville-Dallas-Cleburne - but it really could be just about anywhere here in the central portions of north Texas, so stay alert no matter where you are!

A Flash Flood Watch is in effect for all of north Texas until Saturday evening.

[gboudx]

From jeff:

High tides and coastal flooding increasingly likely Sunday-Monday

Heavy rainfall and possible flooding Saturday-Monday

Strong coastal storm possible Sunday-Monday

Discussion:
Ingredients coming together to produce adverse and moderate to high impact weather event across much of Texas Friday-Monday. Big change today has been the explosive development of Hurricane Patricia off the Mexican west coast growing from a TS to a category 4 hurricane in the last 24 hours. Data from USAF mission this afternoon indicates a very powerful hurricane has evolved today and will landfall on the Mexican coast late Friday and then track across MX and into TX Sunday. Given the extremely intense core of this hurricane, it is likely that a better defined upper level core structure will survive the mountains of MX and reach SW TX early Sunday. This feature will likely help to induce surface low pressure along the middle TX coast which then deepens Sunday into Monday. This is certainly concerning for coastal tidal impacts and now potential for gale force winds across the NW Gulf and coastal counties along with sustained heavy rainfall.

Will not go into much additional detail than that as there is still some uncertainty on exactly how intense the remains of Patricia will be when they arrive into TX and how this helps to develop and interact with the coastal low, but as seen below (there is not much spread in the model tracks).

Impacts:

Heavy Rainfall:
Heavy rainfall is already ongoing over NW TX and this band will slowly move SE on Friday into C TX and then SE TX on Saturday (afternoon). Moisture profiles are near record levels by Saturday over S TX as mid and high level moisture from Patricia pours NE into the region and low level Gulf inflow is maintained. PWS progged to rise to 2.3-2.6 inches over the region which is easily +2SD above late October normals. Models are certainly showing some excessive rainfall pockets, but are not consistent on where these pockets will be. General experience is that we will not know where the most significant rainfall will happen until it is underway and usually this is a function of training bands. See no reason at the moment to change the previous rainfall forecast.

4-6 inches W of I-45
2-4 inches E of I-45

Isolated locations will likely see 6-8 inches and even 10 inches or greater cannot be ruled out especially from Matagorda Bay northward to near College Station.

While grounds are dry this rainfall magnitude will certainly cause run-off and significant rises on area watersheds. Additionally, nearly saturated air column will support high hourly rainfall rates leading to potential urban flooding.

Tides:
Getting increasingly worried on the tides and threat of more significant coastal flooding Sunday-Monday. Utilization of ET-storm surge model run of the GFS forecast model shows storm surge values of 1.0-1.5 ft by Sunday along the upper TX coast as a function of increasing E to ESE winds over the NW Gulf on the eastern flank of the developing surface reflection. This storm surge is a function of sustained ENE winds over the last several days which is trapping high tides on the coast and additional increasing wave action due to stronger winds (near or over gale force) by Sunday. Total water level rises on the coast of 4.0-5.0 ft are now possible which is at or above our coastal flood warning criteria.

Water levels of this magnitude would likely result in overwash and flooding on Bolivar, the west end of Galveston Island, portions of Surfside and Freeport, portions of Seabrook/Kemah/Shoreacres/Baytown/Nassau Bay. Some locations could become cut-off during high tides and some coastal roads may be inundated for a long period of time. Toward Matagorda Bay tides of 4.0-4.5 ft will be possible along the west side of the Bay from Port Lavaca southward to Port O Connor and this would likely cause some minor coastal flooding. Critical levels where more widespread coastal flooding and impacts begin range from 4.0-5.0 ft at various locations along the upper TX coast and in the inland bays. Even with values around 3.5-3.7ft this morning there were impacts on Bolivar and at Nassau Bay.

Will need to monitor this aspect very closely over the next 24-48 hours as any additional increase would only result in greater impacts.

Winds:
ESE winds today have really increased into the 20-30mph range and expect slightly lower speeds on Friday. Developing surface low on Sunday will really ramp up wind speeds possibly into high end Small Craft Advisory levels or Gale Warning levels. Could see a large area of sustained 30-45mph winds Sunday into Monday over the Gulf waters and inland bays. Still too early to be certain, but will watch this aspect.

Highlights:

· Prolonged heavy rainfall event from Saturday afternoon in Monday
· Elevated coastal tides Friday-Saturday (minor impacts)
· Near or above warning criteria tides Sunday/Monday (impacts becoming more likely)
· Winds increasing Sunday to 30-45mph coast to 25-35mph inland
· Seas building 8-10ft over the weekend over the Gulf waters

Impacts:

· Urban flooding (street) possible Saturday-Monday
· Rises on area bayous/creeks likely
· River rises (possibly to bankfull) next week
· Coastal flooding impact to roads, low lying areas, docks, some homes Sunday/Monday especially at high tide
· High wave action will likely result in beach and dune erosion
· Hazardous marine conditions Sunday-Monday…small craft may need to remain in port
· Dangerous rip currents…Galveston Beach Patrol reports strong rip currents and these will continue due to building wave action.

[Brent]

We have thunder... or at least what I remember thunder to sound like.

[gpsnowman]

Power went out for a bit here in SGP. Traffic lights on Carrier parkway are all flashing red. No thunder or lightning but a decent shower happening now.

[Ntxw]

People seem to forget how to drive in rain. Seriously. A little rain in the evening commute and took me twice as long.

[Jarodm12]

Look to the far south west, a severe thunderstorm watch has gone up with increasing rotation on two supercells, this is interesting considering the right turn they have taken in the last few frames of radar. The evolution of this area is intriguing.

[gpsnowman]

Yep very slow earlier. I actually turned my car lights off instead of turning on my wipers, forgetting where they were located exactly. Been a while. This is almost as exciting as watching a snowstorm move in on S2K.......Almost

[Ntxw]

Patricia is on the verge of category 5. Winds 150mph. I bet recon finds stronger later this evening, this is one of the most intense hurricanes you will ever see on our side of the hemisphere...holy cow. Raw T#s is near 8, that's upper class like Wilma and Gilbert.

[Brent]

The HRRR is showing that band of heavy rain setting up over the DFW metro later this evening through the morning rush tomorrow

and yes Patricia is incredible.

[TheProfessor]

Patricia is on the verge of category 5. Winds 150mph. I bet recon finds stronger later this evening, this is one of the most intense hurricanes you will ever see on our side of the hemisphere...holy cow. Raw T#s is near 8, that's upper class like Wilma and Gilbert.

That's going to be terrible for the folks down in Mexico, but thank goodness that monster won't be making landfall in a major U.S City. I'm not sure how many people it will affect in Mexico, but a Hurricane that RI's close to land and is about to hit a city with 1 million+ people = a very bad day.

[Ntxw]

That's going to be terrible for the folks down in Mexico, but thank goodness that monster won't be making landfall in a major U.S City. I'm not sure how many people it will affect in Mexico, but a Hurricane that RI's close to land and is about to hit a city with 1 million+ people = a very bad day.

It may just intensify up until landfall, Cat 5 landfalls are rare globally. Going to be a very bad day for someone along that coast. I'm not sure the populations there but huge canes skirt off the coast often so I'm guessing it's not as heavily populated and more mountainous vs further south (acapulco) or baja. Regardless scary for them.

[Ntxw]

And it looks like Halloween is gradually appearing to be chilly, damp, and wet. Courtesy of this beast . Who says the El Nino doesn't do anything?

[TheProfessor]

Looks like a non tropical version of Patricia could drop close to 3 inches of rain here in Central and Southern Ohio next week, I saw a wind map showing some 40 mph gusts with the rain, walking to class in cold rain with 40 mph winds isn't very fun.

[Ntxw]

Raining cats and dogs by the big Airport






Edit: Patricia did it 140kt = Category 5

[weatherdude1108]

Patricia is on the verge of category 5. Winds 150mph. I bet recon finds stronger later this evening, this is one of the most intense hurricanes you will ever see on our side of the hemisphere...holy cow. Raw T#s is near 8, that's upper class like Wilma and Gilbert.

Usually those systems form right there and move out in the middle of the Pacific where they intensify anfd die. We are making history here!

[Ntxw]

Usually those systems form right there and move out in the middle of the Pacific where they intensify anfd die. We are making history here!

By the next advisory it may be 150-155kts. That's over 170mph or equivalent to an EF4 tornado. Imagine for the folks on that coast if it made landfall as such. Hours of that not 2-3 minutes. If you haven't seen iCyclone's chase video of cat 3 Odile on Cabo last season, it's hard to fathom what a cat 5 would do.

[dhweather]

People seem to forget how to drive in rain. Seriously. A little rain in the evening commute and took me twice as long.

They literally LOSE THEIR MINDS if it rains, deer in the headlights. And it it's below 40 and raining, 5 MPH.

[dhweather]

Usually those systems form right there and move out in the middle of the Pacific where they intensify anfd die. We are making history here!

By the next advisory it may be 150-155kts. That's over 170mph or equivalent to an EF4 tornado. Imagine for the folks on that coast if it made landfall as such. Hours of that not 2-3 minutes. If you haven't seen iCyclone's chase video of cat 3 Odile on Cabo last season, it's hard to fathom what a cat 5 would do.

CAT 5 JUST SOUTH OF THE GULF (of California)

[Ntxw]

People seem to forget how to drive in rain. Seriously. A little rain in the evening commute and took me twice as long.

They literally LOSE THEIR MINDS if it rains, deer in the headlights. And it it's below 40 and raining, 5 MPH.

There is so much truth to that.



So far this evening DFW has picked up officially 0.63" of rain. Real time near 1"/hr band is moving through the airport now