December 2018: Sunshine Returns New Years Eve

[Ptarmigan]

I prefer the rain to be not on the weekend. Better to be on the weekdays. Nice forum.

[srainhoutx]

The afternoon computer guidance continue a theme that started last week of a potentially wet and stormy late workweek into next weekend. The general idea via the GFS, FV3 GFS (new GFS), Canadian and European models suggest areas from the I-35 Corridor to SE and E Texas into Western Louisiana may see a general 2 to 4 inches of rain with isolated higher totals nearing 6+ inches where heavier storms may train. In the cold sector, the trend today has slipped the wintry mischief a tad S suggesting the Panhandle into portions of N Central Texas and extending on East across the Northern portions of the Gulf Coast States into possibly Atlanta and the Carolinas. The surface low track as of today suggest a Northern Mexico across SE Texas and near the Northern Gulf Coast into Western Florida and Southern Georgia. It is still too soon to know exact deals beyond 3 days, but the trends continue suggest a very Stormy late work week/early next weekend weather event.

[CRASHWX]

Next 10 days goes cold...how cold? Shallow Artic air is hard for models to handle. Then 15 to 20 days of above average temps...then we get a ridge migrate northwest over Alaska and cold comes back over 2/3 of the US. How long does that last...well into January.

[Cpv17]

The GFS is trending much drier for the late week system especially areas south of I-10.

[djmike]

Yayy. Loving the new site. On to wishing for some Dec fun this year!

[cperk]

This new site is great thank you Andrew and srain and others involved i may not be aware of.

[Katdaddy]

From this mornings Hou-Gal AFD:

Medium range models are still pointing to an active wx period Fri
through Sat morning...though timing/details aren`t in quite as
good of agreement as they were at this time yday. As the western
upper trough advances eastward, large scale lift will begin
increasing across the state. At the surface, we`re still looking
for a surface wave/low to eventually develop along the front and
track eastward along the boundary. This along with a strong llvl
jet flowing nearly perpendicular into the front, very high PW`s
(1.8-2") pooling in advance & favorable diffluence aloft is
pointing toward a possible heavy rain event setting up in or near
the region. Overall instability appears to be lacking, but it`s
something that`ll need to be monitored with time in regards to any
severe wx chances. The most active weather & threat areas should
generally align near where the front is situated when the sfc
wave moves across and convergence is maximized. The 00z GFS is
depicting this occurring further north, ECMWF further south than
yesterday...and I`m pretending not to see the CMC. At this point,
it`s probably best to evaluate trends versus individual model runs
as I`d anticipate seeing additional similar model wobbles in the
next few days. Hopefully they"ll become better aligned and we can
start narrowing down the threat area, should there be one, in the
mid/late week time period. It is a system that should be
monitored...

[srainhoutx]

Monday morning weather briefing from Jeff:

A significant storm system is likely to impact TX late this week and this weekend

An upper level storm system currently off the NW coast of the US will dig SSE and into the SW US and N MX over the next 48 hours and then turn eastward and move across TX late this week. Surface high pressure building into the area this morning will bring fair cool-cold weather today-Wednesday. By Wednesday this high pressure will begin to move eastward allowing SE winds to bring moisture back into the area from the Gulf.

Moisture increasing rapidly early Thursday and expect to see an increase in clouds and then showers by the afternoon and evening hours.

Friday/early Saturday:
A powerful dynamic storm system will move into TX and interact with near record moisture levels over the region. Early Friday morning a slow moving cold air mass will be pushing southward through NW TX. While the surface high helping to guide this cold air mass is situated more over the Great Lakes, the density of such air masses tend to move southward faster than global models indicate…so the actual front could be deeper into the state by early Friday morning than the current global models are suggesting. Where this front is during the day on Friday will be important as it will be the focus for sustained heavy rainfall production.

Strong lift comes to bear across the region Friday into Friday night with widespread showers and some thunderstorms. Currently instability is looking limited, but experience with cool season severe weather events indicate that not a lot of instability is needed along the Gulf coast this time of year to produce severe weather. Of much greater concern is the threat for heavy rainfall as moisture levels rise to near record levels by Friday afternoon as both Gulf and Pacific moisture taps evolve over the area. PWS will increase to near 1.7-1.9 inches which is near the top maximum values for early December and represent moisture more typical of summer than early winter. Those type of moisture values combined with such a dynamic upper air system and a slow moving frontal boundary are strongly pointing toward some sort of heavy rainfall event. Additionally, the formation of a surface low pressure system near/over SE TX Friday afternoon/evening into Saturday morning also raises the threat for heavy rainfall.

There is uncertainty on where the actual frontal boundary will be located Friday and Friday night as this and the track of any surface low will support the maximum rainfall totals in that area. Currently the GFS is focusing the heaviest rainfall just north of our area while the ECWMF and CMC and across much of the northern half of SE TX.

Rainfall Amounts:
While it is still early, widespread rainfall amounts of 2-4 inches look possible with isolated much higher amounts. These totals will likely need to be adjusted in the coming days as forecast confidence increases on where the heaviest rain will fall. Rainfall amounts of this magnitude over a large area will likely result in run-off into area creeks and rivers and result in rises.

[don]

Im starting to get concerned about the heavy rainfall potential with the 0z Euro showing some parts of Harris county getting 7+ inches of rain, and the 0z CMC shows up to 11+inches of rain in some parts of Harris and Montgomery counties.

[sau27]

While we have to get thru this weekend first, all of the models seem to be sniffing an even deeper digging trough for the following weekend. Still pretty far out, but things do appear to be getting more active.

[CRASHWX]

Seem like the long range Temps in the five days around Christmas are cooler than average. Seems they have been trending that way...to somebody who really knows...is that accurate?

[srainhoutx]

Very subtle changes with this afternoons guidance. The greatest threat for the late week storm system continues to be the potential for heavy rainfall across portions of Texas and Louisiana. Lighter amounts of rainfall extend from S Central Texas and along the Northern Gulf Coast into Northern Florida and Southern Georgia. In the cold sector, snow freezing rain and sleet are possible across the Texas Panhandle, Oklahoma into Arkansas, Tennessee, Northern Mississippi, Northern Georgia, the Carolinas and Virginia. The forecast appears fairly straight forward as the various computer models have been very insistent for heavy rainfall over the last 5 days or so. Subtle shifts N and S likely will continue until Wednesday and Thursday when the storm system moves inland along the West Coast and when get in range for the short fuse guidance to latch onto the likely progression of the Cold Frontal Boundary. Best guess for rain begins increasing Thursday afternoon/evening across Central Texas and ramps up Friday into Friday night/early Saturday.

[Andrew]

Hodographs are looking very impressive across this region Friday night. Cyclogenisis could really pump up the low level jet and create wide sweeping profiles. While available energy is limited, plenty of lift will be provided by the upper level trough. I definitely think straight line winds and even isolated tornadoes could be an issue Friday and Friday night across central and east Texas (including SE Texas).

[Samantha550]

Do we have a timeframe that the storms will be coming Friday? My daughter will be leaving Galveston and traveling back to Beaumont after her basketball tournament . They will be traveling back Saturday morning to Galveston.

[SLM87TX]

Same thing timing...I have a big move on Saturday. Will this system be early or late to arrive overall?

[Andrew]

Do we have a timeframe that the storms will be coming Friday? My daughter will be leaving Galveston and traveling back to Beaumont after her basketball tournament . They will be traveling back Saturday morning to Galveston.

Same thing timing...I have a big move on Saturday. Will this system be early or late to arrive overall?

Across central and southwest Texas scattered storms will start Friday morning. That will spread to the northeast over the day including SE Texas. A heavier line is likely to form over central Texas by mid evening and will push southeast through the day. As it currently stands, the strongest storms will move through SE Texas between 8pm and 3am. Still need a day or two to narrow down the timing, but current models indicate this will likely be an overnight Friday event. Conditions will improve pretty rapidly after the front moves through Saturday morning.

[srainhoutx]

Tuesday morning weather briefing from Jeff:

A significant storm system will impact the region late this week and early weekend.

An upper level storm system currently located off the west coast of the US will continue to move SE and into the SW US and NW MX over the next 48 hours. Dry air mass over TX will undergo rapid changes starting late Wednesday as winds turn back to the SE and moisture begins to increase. As surface pressures begin to fall early on Thursday moisture will stream into SE TX from the Gulf of Mexico with PWS rising toward 1.2-1.5 inches during the day. Broad large scale lift will begin to advance into central TX Thursday and expect bands of streamer showers to develop from the coastal bend through central TX with some of this activity likely clipping our western counties.

Friday/Early Saturday:

Highly active weather period is likely.

A strong upper level trough over N MX will move eastward into SW TX early Friday and then cross the state into early Saturday bringing strong lift across an unusually moist air mass. Moisture levels on Friday rise to near record levels for early December with PWS of 1.8-2.0 inches being forecasted over the area which is more common in August. Strong dynamic lift from the upper level trough will promote the formation of deepening surface low pressure system over the coastal bend/SE TX by mid to late afternoon into the evening hours. A strong modified arctic cold front will be slowly moving into SE TX during the late afternoon hours on Friday into Saturday. A slow moving boundary, coupled with ample low level inflow, near record moisture levels, and strong splitting jet stream structure are all pointing toward a heavy rainfall event Friday into Saturday morning. Where the heaviest rains fall is still uncertain, but recent WPC guidance is suggesting a large area of 3-5 inches over much of the area with higher amounts likely.

Given the time of year and the fact that an early freeze has already knocked down much of the vegetation over the area along with the already wet ground conditions, rainfall of this magnitude is going to result in significant run-off. Widespread nature of the event strongly supports significant rises on area rivers, creeks, and bayous.

At the moment severe weather looks minimal with a general lack of instability, however parts of SE TX will likely be within the warm sector air mass on Friday afternoon and evening and experience with such events in the cool season along the Gulf coast in the past has resulted in some severe weather will very little instability in play…so this will be something to monitor over the next few days.

Forecasted Rainfall Amounts (Friday-Saturday):

[Cpv17]

The 12z Euro has anywhere from 2.5 to 6.5” of rain for Friday’s event across southeast TX.

[CRASHWX]

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

[Cpv17]

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.