December 2018: Sunshine Returns New Years Eve

[srainhoutx]

The cold front has pulled up stationary basically along a line from Columbus to Brenham, Huntsville and Lufkin. That boundary likely will fluctuate and continue to be the focal point along and N of the boundary for heavy rainfall throughout the day. A large complex of heavy rainfall of both elevated and possibly surface based storms are indicated late tonight into early Saturday morning and the Coastal low wraps up near the Upper Texas Coast and the main energy with the strong shortwave inland near San Diego makes its way East into Texas.

[DoctorMu]

We're getting crushed up in the NW:

[srainhoutx]

Mesoscale Precipitation Discussion 1042
NWS Weather Prediction Center College Park MD
1029 AM EST Fri Dec 07 2018

Areas affected...Central and Eastern Texas...

Concerning...Heavy rainfall...Flash flooding possible

Valid 071530Z - 072100Z

SUMMARY...Prolonged moderate frontogenetic rain shield with
embedded convective elements increase threat for high rainfall
totals with possible initiation of flooding conditions toward
evening.

DISCUSSION...Very strong synoptic and mesoscale environment
beginning to set up across central to eastern Texas. 15z surface
analysis depicts a strong frontal zone extending northeast from a
weak surface wave near COT/PEZ to a secondary even weaker
inflection near LFK. A dying frontal zone and inverted trof
extend NE and NNE from this low but are weakly defined with
minimal convergence along it at this point. At this second
inflection, a subtle warm front extends south-southeast toward
TX/LA Gulf Coast differentiating higher theta-E air in the warm
sector depicted by upper 60s to mid-70s temps/Tds.

At the western edge of the Gulf mT air mass, increasing southerly
winds at 925-850mb turn southwesterly across the frontal boundary
to eventually parallel in far eastern TX into LA. The southerly
component flow supports isentropic ascent along the frontal
boundary but is enhanced with greater orthogonality to the
boundary further west near the primary surface wave. Radar mosaic
depicts banded cumuliform showers beginning to increase in
intensity and coverage with the approach of better moisture flux
aloft (700-850mb) and upper level ascent/jet forcing approaching
from Coahuila/Chihuahua.

CIRA Layered PW analysis depicts a strong confined moisture plume
streaming over the Sierra Occidental and Mexican plateau,
coincident with the area of concern. RAP analysis/forecasts
suggest little meandering of this plume, to maximized total
moisture in the column. GOES-16/17 Meso sectors depict shortwave
energy upstream in Mexico with downstream ridge axis across
Southeast TX, supporting DPVA and modest divergence aloft at this
time. Additional distant right entrance to 130 kt 3H jet over
OK/MO further evacuates the area over Eastern TX currently.
However, a subtle 100kt jet streak is emerging from the Big Bend
of TX per GOES AMVs. This jet max will strengthen and pass to the
north of the moisture confluence axis in the 17-19z time frame
rapidly enhancing UVVs from divergence aloft. Response in the LLJ
will increase to 20-25kts at 85H advecting 1.75-1.9" Total PWs as
well as slanting 1000 J/kg SBCAPEs to allow MUCAPEs to remain over
500 J/kg. As such the broad area of shield precipitation with
.25-.5"/hr rates will have enhanced convection elements capable of
near or above 1"/hr rates. As such an axis of 1-1.5" totals with
pockets of 2-2.5" totals through 21z will exist across the MPD
area. This is not likely to produce flooding/flash flooding given
dry antecedent conditions, but will set the stage for prolonged
slow rise/inundation through the evening into the overnight hours.

Stronger more efficient thunderstorm activity is likely to exist
in the warm sector at/along Central TX coast and a separate MPD
may be issued for that area later if conditions warrant.

Gallina

ATTN...WFO...EWX...FWD...HGX...LCH...SHV...

[tireman4]

NWS Outlook....

[tireman4]

NWSWGFRC

[Texaspirate11]

Looks like the heaviest rainfall will be north northwest of the bay area....

[Cpv17]

Looks like the heaviest rainfall will be north northwest of the bay area....

Y’all have had plenty of rain down there. I’d bet areas down there have seen twice as much rain this year compared to other areas of the viewing area.

[tireman4]

00
FXUS64 KHGX 071747
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1147 AM CST Fri Dec 7 2018

.DISCUSSION...

18Z Aviation...Widespread SHRA and IFR ceilings ongoing northwest
of the slow moving cold front. This will continue across CLL and
UTS into the overnight hours. Expect the front to edge into CXO
18-19Z. There have been a couple of lightning strikes in the SHRA
band, but they are few and far between. best handled with a VCTS.
Further south, expect to see showers increase during the
afternoon and MVFR ceilings to become more prevalent. Best window
for TSRA appears to be later tonight for IAH and HOU as a band of
heavier convection along the CF nears and moves through. Winds
should become NE later this aft/early eve at IAH/HOU due to a
broad sfc low forming across southeast Texas. Rain should end from
west to east in the 10Z to 15Z window as the sfc low/front
accelerate off to the east and drier air begins to move in. 33

&&

.PREV DISCUSSION... /ISSUED 1028 AM CST Fri Dec 7 2018/

DISCUSSION...
At 10 AM, a cold front extended from near Jasper to just northwest
of Conroe to near Columbus. There is quite a contrast in
temperatures across the CWA with 10 AM values of 50 degrees at
Caldwell to 76 degrees at Lake Jackson. Rainfall is increasing
behind the front and accumulations in parts of Grimes and Walker
counties are already near 1.50 inches.

Coverage is expected to increase later this morning as a speed max
near the Big Bend pushes to the NE. The low level jet is also
progged to increase to 25 knots and this will draw higher PW air
1.7-1.8 inches) into SE TX. The cold front will continue to sag
south this afternoon and precipitation will begin to push south as
well and would expect much of Harris County to start getting
rainfall by early afternoon. Will maintain the Flash Flood Watch,
high rain chances and continue to mention locally heavy rain as
rainfall rates are expected to increase vertical motions and PW
values both increase. Rainfall totals by 00z will average 2-4
inches over the north to around inch over the central zones and
less than inch near the coast. Overnight, another 1-2 inches over
the north and 2-3 inches south/coast. All told, looking at 3-6
inches across the CWA with the higher totals over the north.

The other concern is amount of heating near the coast and the
contribution to higher CAPE/instability values. As the front nears
the coast late this afternoon, will need to watch for the
potential of strong storms as shear values remain impressive and
muCAPE values approach 1000. 43

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 45 50 39 50 35 / 100 20 0 0 0
Houston (IAH) 50 54 42 52 38 / 100 40 0 0 0
Galveston (GLS) 55 59 45 52 44 / 100 70 0 0 0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Flash Flood Watch through Saturday morning for the following
zones: Austin...Brazoria Islands...Brazos...Burleson...
Chambers...Coastal Brazoria...Coastal Galveston...Coastal
Harris...Coastal Jackson...Coastal Matagorda...Colorado...
Fort Bend...Galveston Island and Bolivar Peninsula...
Grimes...Houston...Inland Brazoria...Inland Galveston...
Inland Harris...Inland Jackson...Inland Matagorda...
Madison...Matagorda Islands...Montgomery...Northern
Liberty...Polk...San Jacinto...Southern Liberty...Trinity...
Walker...Waller...Washington...Wharton.

GM...SMALL CRAFT SHOULD EXERCISE CAUTION from 7 PM CST this evening
through Sunday morning for the following zones: Galveston
Bay...Matagorda Bay.

Small Craft Advisory from 7 PM this evening to 7 PM CST Sunday
for the following zones: Coastal waters from Freeport to
Matagorda Ship Channel TX out 20 NM...Coastal waters from
High Island to Freeport TX out 20 NM.

SMALL CRAFT SHOULD EXERCISE CAUTION from 3 PM this afternoon to
7 PM CST this evening for the following zones: Coastal
waters from Freeport to Matagorda Ship Channel TX out 20
NM...Coastal waters from High Island to Freeport TX out 20
NM.

Small Craft Advisory from 7 PM this evening to 11 PM CST Sunday
for the following zones: Waters from Freeport to Matagorda
Ship Channel TX from 20 to 60 NM...Waters from High Island
to Freeport TX from 20 to 60 NM.

SMALL CRAFT SHOULD EXERCISE CAUTION until 7 PM CST this evening
for the following zones: Waters from Freeport to Matagorda
Ship Channel TX from 20 to 60 NM...Waters from High Island
to Freeport TX from 20 to 60 NM.

&&

$$

Discussion...33

[Texaspirate11]

Looks like the heaviest rainfall will be north northwest of the bay area....

Y’all have had plenty of rain down there. I’d bet areas down there have seen twice as much rain this year compared to other areas of the viewing area.

Very true! I'll share the rain!

[unome]

getting breezy in Cypress, still in low 70s right now though

https://www.wrh.noaa.gov/zoa/mwmap2.php?map=zhu
https://www.wrh.noaa.gov/zoa/mwmap2.php?map=houston
https://earth.nullschool.net/#current/w ... 30.04,2827
https://earth.nullschool.net/#current/w ... 30.04,2827

[jasons2k]

It feels wonderful outside!! Warmer than I expected it to be today but I’ll gladly take it. I wish I was at home so I could go for a run before the rain moves in.

[sau27]

I fear that because this storm has been so well advertised for almost a week now the general public's (ie non weather geeks) expectations are out of whack. I agree that we should all be prepared for a worst case scenario, but if disruptive flooding does not occur I worry this event will be labeled a bust by most people. Its a catch 22. Better modeling gives us a better picture earlier on but it also allows hype to build for many days can distort expectations.

[sau27]

I fear that because this storm has been so well advertised for almost a week now the general public's (ie non weather geeks) expectations are out of whack. I agree that we should all be prepared for a worst case scenario, but if disruptive flooding does not occur I worry this event will be labeled a bust by most people. Its a catch 22. Better modeling gives us a better picture earlier on but it also allows hype to build for many days can distort expectations.

And I am not putting that on the meteorologists. I think they have done a fabulous job. I am saying some local media is playing this up doing stories on high water vehicles and focusing everything on the isolated 10 inch possibility rather than the more likely 3-5 inch outcome most people will see.

[srainhoutx]

Cold front has passed DW Hooks

[srainhoutx]

Mesoscale Precipitation Discussion 1043 NWS Weather Prediction Center College Park MD 231 PM EST Fri Dec 07 2018 Areas affected...Central Coastal Plain of TX... Concerning...Heavy rainfall...Flash flooding possible Valid 071930Z - 080030Z SUMMARY...Warm sector enhanced convection with potential for repeat tracks, may lead to isolated flooding/flash flooding through early evening. DISCUSSION...GOES-16 WV suite depicts leading edge of greatest height-falls are approaching across South Texas. This leads to favorable eastward shift of the ridge axis and placement of the warm sector across the coastal plain of Texas to be within the right entrance to the 90kt 3H jet streak enhancing vertical ascent and strengthening of low level inflow fairly orthogonal to the frontal zone draped from N of ALI to N of VCT to deepening surface wave NW of Houston Metro area. Sfc inflow of 15-20kts near CRP is advecting high Theta-E air (70F Tds) off the Western Gulf, and CIRA LPW fields suggesting saturated profiles starting to align over the front leading to total PWat values in the vicinity of 1.75" per GPS network. While cloud cover has limited solar insolation, temps to 75F support 750-1250 J/kg of SBCAPEs with consistent replenishing flow, though slowly veering with time. 10.3 um channel has shown continual shield of cooling tops, but now embedded overshooting CBs in Bee/Goliad county have reached -65C increasing the vertical depth for rainfall generation, likely indicating rates up to 1.75"/hr are probable in the next few hours. Cell motions to the NE at 20kts are likely to limit the duration at any given point to produce flash flooding, but it is the veering wind profiles and persistent and slowly increasing LLJ as the main height-falls approach that should support additional upstream development. As such repeat tracks are possible especially near coastal zones where enhanced convergence from friction at bay/inlet/cove intersections are likely to aid in the redevelopment process. Limiting factor is clearly dry antecedent conditions across the region, though reduced soil infiltration due to transition to winter ground conditions may support more runoff than FFG values would suggest, still flash flooding should be limited in scale and coverage, even the most aggressive Hi-Res CAMs such as the GEM-Regional, HRRR and HRRR-Experimental are only 2-3" through 00z, from San Patricio to Wharton/Matagorda county. Observational trends are favoring these models' orientation and evolution to suggest flash flooding may be possible through evening hours. Gallina ATTN...WFO...CRP...EWX...HGX...

[tireman4]

Here...it...comes....

[BlueJay]

Oh the weather outside is frightful!

It's rainy and coldish.

[CrashTestDummy]

Cold front has passed DW Hooks

Interesting! You can just make out the line amongst the overriding precip. I do, though, hope most of it stays north of us. Our back yard _just_ got so that there was no standing water. I fear our 'Pearland pumps' (rubber rain boots) will be needed to set foot out the back door.

[sau27]

The past couple HRRR runs have ramped up the rainfall over the metro area. Interesting development.

[don]

Latest few runs of the HRRR model have moved the heaviest axis of rain along the 59 corridor,it really has things picking up around 6 this evening.