December 2018: Sunshine Returns New Years Eve

[Ounce]

A lot of High School Football playoff games Friday night...I wonder how many delays or cancelations will take place?

I just posted about this on another site. I’m sure there will be plenty of them. It’s rare to get this kind of rainfall here in December.

Timing and placement will be major factors.

[jasons2k]

It was chilly today, even out in the sun. At least it's not expected to freeze this week

[Texaspirate11]

I'm so ready for summer.

[Katdaddy]

Another chilly morning across SE TX. Changes begin tomorrow with a marginal risk area of severe storms across S TX. Heavy rain will be the concern across SE TX Friday night into Saturday morning with 2-5” however some isolated totals up to 10” will be possible.

[srainhoutx]

Wednesday morning weather briefing from Jeff:

A significant storm system will bring high impacts to SE TX Friday and Saturday

Widespread heavy rainfall and flooding increasingly likely

A strong storm system currently off the CA coast will move offshore today and into the SW US/NW MX tonight into Thursday and then arrive into TX on Friday into Saturday. Surface high pressure is starting to move eastward this morning and winds will return to the SE later today and begin to advect moisture into the area. Clouds will rapidly increase from west to east late today and tonight and expect mostly cloudy conditions on Thursday. A weak short wave will eject out of the trough and across TX on Thursday and this feature combined with deepening moisture levels will likely result in streamer showers from the coastal bend NNE across C TX and into our western counties by the afternoon hours.

Friday-Saturday midday:

Significant weather event increasingly likely.

Strong trough will begin to move into TX with both a surface cold front and surface low pressure system arriving across SE TX Friday evening. Moisture levels are still forecast to rise to near record or even exceed record levels by Friday evening with the advancement of two source streams over the area from the deep southern Gulf and the eastern Pacific. PWS are forecasted to rise to near 2.0 inches which for early December is near the maximum values. In fact a review of Lake Charles historic PW plots indicates that the highest early December value ever record was 1.98 inches and for Corpus Christi 2.07 inches. The maximum moving average for Lake Charles for this time of year is around 1.8 inches and the 90% average is 1.35 inches…to put is simply there is going to be excessive amounts of moisture in place that is fairly uncommon during this time of the year.

In additional to the deep tropical moisture profile, a slow moving SW to NE oriented frontal slope which will be nearly perpendicular to the upper level winds from the SW will be crossing the area and a surface low pressure system will likely form somewhere in/near SE TX. A low level jet of 45-55kts will develop from the TX coast bend into SE TX Friday afternoon and support both strong moisture and temperature advection across the region. Low level inflow will become maximized early Saturday morning over the region with the formation of the surface low. Upper level divergence will increase with the trough progressing into SW TX late Friday helping vent convective elements. All of these ingredients point toward a widespread heavy rainfall event.

Rainfall Amounts:

Widespread rainfall amounts of 3-5 inches are likely with significantly higher totals of 6-9 inches under sustained training bands. While it is still uncertain where the heaviest rains will fall, some of the latest global model guidance and the longer term short range guidance is starting to favor area along and N of US 59 for the heaviest axis of rainfall. Interestingly the CMC model has been fairly consistent in its axis of very heavy rainfall from about I-10 NNE toward the Lake Livingston area, while the GFS continues to favor areas just north of our area. For consistency, the GFS continues to produce a point rainfall for IAH of over 3.0 inches for this event.

Hydro:

Grounds are fairly wet over the region given both the time of year and recent rains in October with KBDI values of 0-200 across much of the eastern half of TX and 6-hr flash flood guidance values of 4.5 inches for Harris County. Since the area has already experienced an early season killing freeze, most vegetation is dead or dormant which is leading to little to no soil evaporation. Given the expected widespread nature of the rainfall totals, significant rises on area rivers, creeks, and bayous is becoming likely with this event and some locations may reach or exceed flood stage. Additionally, high rainfall rates with convective elements support local street flooding conditions in urban areas.

I want to be clear that rainfall of these amounts this time of year will have a significantly different response on area watersheds than during the warm season months…a more run-off will be generated.

Decision Support:

Timing: Friday afternoon-midday Saturday
Rainfall Totals: 3-5 widespread, 6-9 isolated
Location: heaviest rainfall likely will focus along and N of I-10, but this remains in flux
Confidence: event confidence is high, location is heaviest rainfall remains low to moderate

Forecasted Rainfall Totals (Friday-Saturday):

12052018 Jeff 1 untitled.png

Excessive Rainfall Outlook (Friday):

12052018 Day 3 Excessive Rainfall 99ewbg.gif

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[jasons2k]

That’s a lot of heavy rain over a large area. Rivers and creeks will fill-up quickly so keep an eye out.

[CRASHWX]

30 degrees in Central Hardin County this morning...not much frost...guessing thee dew point was mid 20’s?

[srainhoutx]

NWSWGRFC‏Verified account @NWSWGRFC · 8m8 minutes ago

Heavy rain is expected late this week into the weekend across a large portion of Texas. Widespread minor to moderate river flooding with isolated major flooding is possible! #txwx #txflood #ntxwx #ctxwx #houwx #txwater

[Andrew]

Where cyclogenisis occurs will likely be key for the heavy rainfall placement this rain event. While upper level moisture and lift will be available across all of the state, how far the warm front lifts north and low pressure forms will likely dictate where the heaviest totals occur. Currently the GFS has been shifting this further and further south across South Texas. The NAM takes it over central and SE Texas and the ECMWF takes it across Bryan. Having that low level jet ramp up will pool a lot of moisture into the region where it does form.

[sambucol]

Will we have high winds with this?

[sau27]

Will we have high winds with this?

Seems unlikely on a widespread basis. Locations closer to the coast seem to have a better shot at thunderstorms and possible spin up tornadoes, but even with that the threat looks to be fairly minimal.

[stormlover]

Looks like a pretty significant event

[sambucol]

Will we have high winds with this?

Seems unlikely on a widespread basis. Locations closer to the coast seem to have a better shot at thunderstorms and possible spin up tornadoes, but even with that the threat looks to be fairly minimal.

Would those winds be likely in the Baytown area? Thank you.

[srainhoutx]

The Weather Prediction Center issues a Moderate Risk for Excessive Rainfall across portions of S Central and SE Texas for Friday into early Saturday.

[stormlover]

Srain when is the event supposed to end? Saturday night? Saturday morning? By noon on Saturday ?

[srainhoutx]

Sambucol, Baytown and the upper reaches of Galveston Bay may need to pay attention during the early morning hours of Saturday as the Coastal low looks to be nearby. Stormlover, the trends have slowed just a tad suggesting we may not completely get the rain out of our hair until possibly midday on Saturday for some folks in SE Texas including our neighbors in the Golden Triangle.

[stormlover]

Yeah I am in the golden triangle!! Thanks

[srainhoutx]

Yeah I am in the golden triangle!! Thanks

This would be a perfect time to Update your profile and location in your user control panel. That helps our Pro Mets and other folks get a general idea where you are located... Cheers!

[harp]

Meanwhile, nothing fun on the horizon as far as winter precip is concerned....

[snowman65]

Meanwhile, nothing fun on the horizon as far as winter precip is concerned....

I think you can scratch anything for this winter. El Nino is a party-pooper....