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2:00 am

just a reminder, the NHC still gives the Gulf blob a 20% chance of developing over the next 2 days

https://www.nhc.noaa.gov/text/refresh/M ... WOAT.shtml

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Sun Jun 17 2018

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A surface trough is producing a large but disorganized area of
showers and thunderstorms over the west-central and northwestern
Gulf of Mexico. Strong gusty winds to near 40 mph are accompanying
some of the stronger thunderstorms. Environmental conditions do
not support significant development. However, heavy rains and gusty
winds are likely to continue across the northwestern Gulf of Mexico
through tonight. This activity will reach portions of the Texas and
southwestern Louisiana coasts later tonight and on Monday. For more
details on this disturbance, please see products issued by your
local weather office and High Seas Forecasts issued by the National
Weather Service.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...low...20 percent.

&&

High Seas Forecasts issued by the National Weather Service can be
found under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and
on the Web at https://ocean.weather.gov/shtml/NFDHSFAT1.shtml.

$$
Forecaster Stewart

stormlover wrote:Brooks, will this be a bust??? Wasn’t it supposed to be heavy rains all day today

No, today was not a bust. We could never commit to specifics due to the inherent uncertainty of tropical forecasting. It downpoured periodically almost exactly as forecast. The the heaviest banding rain may happen Monday night and Tuesday or maybe not — as it’s dependent on if a low forms and LLJ. Either way by Tues we’ll see a widespread storm total of 3”-6” with isolated 8”+. (We got 2” at my house today.)

current days 1-3 QPF http://www.wpc.ncep.noaa.gov/qpf/d13_fi ... 9282959083

Cromagnum wrote:

MontgomeryCoWx wrote:

stormlover wrote:Brooks, will this be a bust??? Wasn’t it supposed to be heavy rains all day today

To me, it looks like we will have more rain than expected. At this point, a bust seems very unlikely unless your benchmark was 6 inches of rain.

When models are calling for a foot of rain, anything less than a few inches is a miss for sure.

Models are just one tool. They don’t represent, “the forecast.” (At least not mine There are a dozen common models we use with a dozen different rainfall forecasts. The forecast we had was “80% ch. rain” with some street flooding possible, mostly Sunday night and a Monday.

Sunday evening briefing from Jeff:

Rainfall heavy threat increasing tonight into Monday

Waves of brief heavy rainfall have passed over the region today, but storm motions have been fast enough and with enough break between bands to prevent any significant flooding concerns. Some areas have picked up 1-2 inches of rainfall today and across those area the grounds are starting to saturate.

Models are continuing to have a difficult time with the position of sustained heavy rainfall tonight into Monday. A look at satellite images shows a large mass of deep tropical convection across the NW Gulf of Mexico which will be approaching the coast later tonight into Monday. Where a surface trough/or coastal front anchors due to low level speed convergence will likely be the location where the heaviest rains will fall. There is little agreement even with the short term high resolution models on where this may occur…so confidence remains low.

Rainfall Amounts:
Additional rainfall amounts of 2-4 inches are likely across much of the area with totals of 4-6 inches S of a line from Chambers County to Wharton and 1-3 inches N of a line from Hempstead to Livingston. Isolated amounts of 8-10 inches will be possible where any training bands develop. Storm totals look heaviest around Matagorda Bay, but once again I stress that current model performance is not good and the position of the heaviest rainfall continues to change with nearly each run.

WPC has outlooked the southern portion of the area in a slight risk for flash flooding and is considering raising that risk for portions of the area into a moderate risk once it become clear where the more sustained training will form tonight into Monday.

Hydro:
Will need to continue to monitor rainfall rates and especially the short duration rates. Grounds will gradually saturate allowing greater run-off potential over the next 24-48 hours and rises on area watersheds.

Note: Addicks/Barker gates were closed at 0800 this morning (Sunday).

Forecasted Rainfall Next 5-days:

I’ve had .89” so far, on day one with more showers developing to my southeast. I’d say not a bust so far, at least up here.

Cromagnum wrote:

MontgomeryCoWx wrote:

stormlover wrote:Brooks, will this be a bust??? Wasn’t it supposed to be heavy rains all day today

To me, it looks like we will have more rain than expected. At this point, a bust seems very unlikely unless your benchmark was 6 inches of rain.

When models are calling for a foot of rain, anything less than a few inches is a miss for sure.

Just to be clear, the models have been calling for those amounts only in isolated locations, and in many cases offshore. Follow the guidance posted by Jeff and others:

Rainfall Amounts:
Additional rainfall amounts of 2-4 inches are likely across much of the area with totals of 4-6 inches S of a line from Chambers County to Wharton and 1-3 inches N of a line from Hempstead to Livingston. Isolated amounts of 8-10 inches will be possible where any training bands develop. Storm totals look heaviest around Matagorda Bay, but once again I stress that current model performance is not good and the position of the heaviest rainfall continues to change with nearly each run.

WPC has outlooked the southern portion of the area in a slight risk for flash flooding and is considering raising that risk for portions of the area into a moderate risk once it become clear where the more sustained training will form tonight into Monday.

I keep watching that mid-level vortex, SE of Galveston, for convergence on the N/NE/E/SE quadrants as it comes ashore. It still has a ways to go overnight.

Still a huge gradient in the models. GFS, NAM are below - we're back to nowcasting.

The prevailing theme seems to be more of the same, just more of it. Rainfalls will be focal and variable. Banding should be thicker and more sustainable tomorrow and Tuesday.

Not much change in my eyes from today's model runs. Maybe a little further north with the heavier rain but overall events are proceeding as expected. Still thinking widespread 3-5 with isolated 8-10 inches (especially South and West of Houston). Now, if a band starts to train, things could change rather quickly. Going to have to radar watch for that over the next couple nights.

Seeing some changes overnight from the WPC regarding rainfall potential as well as the Excessive Rainfall Outlooks into Wednesday. Everything has shifted up the Texas Coast where the Highest heavy rainfall chances over the next 5 Days appears to be from the Middle Texas Coast to the Upper Texas Coast. Those yellows represent 10+ inches near Matagorda Bay/Victoria with 7+ inches across a good portion of SE Texas.
The Excessive Rainfall Outlooks have us in a Slight Risk for today with Moderate Risks for Tuesday and Wednesday.

NHC's interactive graphical marine forecast map is the best tool they've come up with imo

https://www.nhc.noaa.gov/marine/forecas ... ed_gom.php
https://www.nhc.noaa.gov/marine/forecast/info.php?large

Synopsis for the Gulf of Mexico
454 AM EDT Mon Jun 18 2018

.SYNOPSIS... The combination of a mid to upper trough over the SW Gulf and surface broad low pressure over the western gulf will continue to result in numerous showers and thunderstorms over much of the central and northwestern gulf waters through Tue. A tight pressure gradient between the low pressure and high pressure over the eastern gulf will maintain strong southeast to south winds over the waters W of 90W through Wed. Fresh to locally strong southeast winds will continue over the W central gulf and SW Gulf waters through Thu. High pressure ridging extending from Atlantic to across the northern gulf will dominate the gulf Thu through Fri night as it shifts southward.

Hazardous Weather Outlook
National Weather Service Houston/Galveston TX
441 AM CDT Mon Jun 18 2018

TXZ163-164-176>179-195>200-210>214-226-227-235>238-300-313-
335>338-190945-
Austin-Brazos-Burleson-Chambers-Coastal Brazoria-
Coastal Galveston-Coastal Harris-Coastal Jackson-
Coastal Matagorda-Colorado-Fort Bend-Grimes-Houston-
Inland Brazoria-Inland Galveston-Inland Harris-Inland Jackson-
Inland Matagorda-Madison-Montgomery-Northern Liberty-Polk-
San Jacinto-Southern Liberty-Trinity-Walker-Waller-Washington-
Wharton-
441 AM CDT Mon Jun 18 2018

This hazardous weather outlook is for portions of Southeast Texas..

.DAY ONE...Today and Tonight

Scattered to numerous showers and thunderstorms will be possible
today. Locally heavy rain will be possible and may result in minor
flooding. Tropical funnel clouds may also be possible.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

Scattered to numerous showers and thunderstorms will be possible
Tuesday through Thursday. Locally heavy rain will be possible and
may result in minor flooding. Tropical funnel clouds may also be
possible.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report rain totals or any flooding
observed to the National Weather Service.

HRRR, while it has been struggling some over the last couple runs, suggests a lot of convection will break out along the coast and over a lot of SE Texas over the next 4-5 hours. Going to have to keep an eye on any training that could setup.

Yes the HRRR is really aggressive today, lets hope this doesn't verify today.The Tech WRF also looks similar.

don wrote:Yes the HRRR is really aggressive today, lets hope this doesn't verify today.The Tech WRF also looks similar.

Yea that is why I didn't post the QPF because its way too aggressive, but it can be useful to see the trend and that is additional coverage for much of SE Texas.

Monday morning briefing from Jeff:

Heavy rainfall possible today-Wednesday

Mid level low pressure system over the NW Gulf of Mexico combined with a surface trough near the TX coast and an extremely moist air mass with PWS of 2.1-2.3 inches will continue to promote waves/bands of rainfall over the next 24-48 hours….some of this rainfall will be heavy at times. Satellite images show a broad mid level circulation over the NW Gulf of Mexico with recent cooling cloud tops (thunderstorms) having formed well to the SE and also near the center of this feature. Satellite derived products show extensive moisture is in place across the NW Gulf of Mexico with PWS of 2.3-2.5 inches continuing to advance toward the TX coast. Thus far bands/waves of showers have been moving fast enough and have not trained over one particular area long enough to cause any problems. Unidirectional and increasing ESE/SE wind flow today and tonight will support increasing banding of fast moving showers and thunderstorms…storm motions should remain in the 15-20mph range…but banding and training could result in quick intense rainfall accumulations even with the fast storm motions.

Rainfall Amounts:
Widespread rainfall amounts of 3-6 inches will be likely S of I-10 with 2-4 inches north of I-10. Isolated higher totals of 8 inches or greater will be possible with the most likely area for those higher totals along an SW of a line from Galveston to Wharton. Moisture levels are extremely high and will support rainfall rates of 1-3 inches per hour in the stronger cells. WPC amounts (see below) have been adjusted higher across portions of SE TX, but there continues to be enough uncertainty as to where and when this heavy rainfall banding may occur.

Overall the current forecasted amounts of rainfall are likely to be handled by the creeks and bayous over the area as long as the rainfall continues to exhibit enough breaks allowing systems to drain. Grounds will slowly saturate as the rainfall totals add up leading to greater amounts of run-off as the event continues. While rises on area creeks and bayou will be possible, the main threat will be street flooding especially in any areas of intense rainfall.

WPC has upgraded portions of the area into a moderate risk for flash flooding Tuesday into Wednesday.

Marine:
Long period swells are currently arriving along the TX coast with tides running about .5-1.0 foot above normal. Total water levels along the Gulf facing beaches are running 2.5-3.2 feet at times of high tides and may result in some minor coastal flooding. Tidal conditions should gradually improve into Tuesday.

A bit worrisome to see that mid level circulation moving almost due North toward the SE Texas Coast this morning. We've had a couple of peaks of sun already this early morning and whatever dry air at 700mb seems to have saturated as inbound/outbound aircraft for IAH (Bush) are leaving contrails. HGX is closely monitoring and if need be, Flood Watches will be hoisted sometime today depending on how the QPF plays out.

Tropical Rains Today