Severe Thunderstorm Warning 27, NWS Houston/Galveston, TX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
337 PM CDT Sat Apr 6 2019

.DISCUSSION...
A warm front has pushed north of the region and showers and
thunderstorms along and north of this feature have also moved to
the north. Short term guidance suggests that this band of showers
and storms will sink back to the south this evening from 00-03z
and feel the building cold pool to the north should nudge the
convection south before it dissipates. Depending on how much rain
falls this this evening will determine whether a Flash Flood
Watch is required later tonight. Rainfall over the last month or
so has been below normal and the 1/2 inch of rain or so today
doesn't warrant an FFA but if heavy rain falls this evening over
the NW zones, then a Watch will probably be needed for Sunday. The
rest of the region will probably only have to deal with some
spotty showers through 09z. Fog has dissipated along the coast
but with warm and moist air flowing over "relatively" cooler shelf
waters, conditions still remain favorable for sea fog. SREF
ensemble guidance continues to target the coast with fog tonight
and again Sunday night. Convective mixing/stronger winds may
mitigate the fog threat but feel its best to keep a mention of fog
over the near shore waters and the adjacent coastal areas.

Water vapor shows a strong upper level disturbance over Mexico.
This feature should approach SE TX between 09-12z. A mid level
speed max coupled with a nice split in the jet and PW values
between 1.55 and 1.75 inches should set the stage for widespread
showers and thunderstorms. Am expecting the activity to redevelop
between 07-09z and increase in coverage and intensity as it tracks
across the region. A weak surface low looks like it'll develop
over the SW zones and this could focus some brief training of
precipitation along the US 59 corridor for a time early Sunday
morning. At this time, prefer a blend of the TT WRF and the HiRes
NMM. These models develop an MCS over SC TX and move the feature
NE across the area. Rainfall amounts will be strongly dependent on
rainfall rates and if training of storms can develop. Will
maintain mention locally heavy rain in the weather grids along
with the mention of severe storms possible. At this time, strong
damaging winds looks to be the primary severe hazard on Sunday. High
PoPs certainly seem to be in order for Sunday. FWIW, the HiRes
ARW hints at an outflow boundary moving into the Gulf and shutting
down the convection by 18z. The HiRes guidance keeps the upper
low over the region through Monday with wrap around moisture
lingering across SE TX. Kept rain chances going Sunday night into
Monday as the upper level feature gradually exits the region.

Upper level ridging amplifies over the state during the mid week
period. It should dry out as heights build. Another upper
level trough will approach next weekend and this feature should
bring additional shra/tsra next Saturday. 43

&&

.MARINE...
Southeasterly winds will prevail through the weekend over average 2
to 4 foot significant sea heights. A developing coastal low over
South Central Texas will move up into eastern Texas tomorrow
morning. As this low advances northeast up into southeastern Texas,
a line of downstream thunderstorms will form and push through the
local waters sometime during the late morning and/or early Sunday
afternoon hours. While early morning southeasterlies will
temporarily strengthen ahead of this advancing low, it will be a
potential squall line passage that significantly boosts winds and
agitates the sea state. Thus, while Caution flags may not be
required tomorrow morning, anticipate the approach and passage of a
strong line of thunderstorms that will likely initiate upper Texas
bay and Gulf water Special Marine Thunderstorm Warnings. Mariners
need to pay very close attention to the radar and short term
forecasts before considering leaving port Sunday morning.

Winds will veer west to northwest with the approach and passage of a
Monday cold front. Winds in the wake of this front will be
relatively light and high pressure moving in behind it will maintain
weak and variable breezes going through Tuesday. The strongest
onshore gradient winds of the week will be from Wednesday morning
through early Thursday in response to the next approaching upper
trough. The onshore pressure gradient will remain tight enough to
most likely hoist Caution (possible offshore Advisory) flags at mid
week. Another weak front may make it into the nearshore waters and
briefly pick northeasterlies up to Caution levels late Thursday into
early Friday. 31

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      67  74  60  79  58 /  60  80  60  20  10
Houston (IAH)              69  75  62  80  60 /  50  90  50  20  10
Galveston (GLS)            68  73  65  76  65 /  30  90  50  20  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

Hazardous Weather Outlook
National Weather Service Houston/Galveston TX
527 AM CDT Sat Apr 6 2019

TXZ163-164-176>179-195>200-210>214-226-227-235>238-300-313-
335>338-436>438-071030-
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-
527 AM CDT Sat Apr 6 2019

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

.DAY ONE...Today and Tonight

There is a slight risk of severe weather along and north of a
Columbus to Livingston line. There is an enhanced risk of severe
weather along and north of a Bryan to Lufkin line. The main
threats will damaging straight line winds and hail from a line of
storms. A brief tornado cannot be ruled out. There is also a
threat for heavy rainfall over the same area as the enhanced
severe weather risk.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

There is a slight risk of severe weather for all of the area on
Sunday. Again the main threats will be damaging winds and hail but
a brief tornado may still be possible. There is a higher risk for
heavy rainfall and flooding over the area on Sunday. Most areas
could get 2 inches of rainfall or more from storms moving across
the area.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed today and Sunday.

GMZ330-335-350-355-370-375-071030-
Coastal waters from Freeport to Matagorda Ship Channel TX out
20 NM-Coastal waters from High Island to Freeport TX out 20 NM-
Galveston Bay-Matagorda Bay-
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-
527 AM CDT Sat Apr 6 2019

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

.DAY ONE...Today and Tonight

Dense sea fog will be possible this morning through tonight.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

The threat for sea fog will continue into Sunday and Monday.
Thunderstorm activity will be more numerous Sunday with the
potential for severe weather along the coast and through the bays.
Damaging winds will be the main threat along with heavy rainfall.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed today and Sunday.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
609 PM CDT SAT APR 06 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0605 PM     FUNNEL CLOUD     7 E WIXON VALLEY        30.76N  96.20W
04/06/2019                   BRAZOS             TX   STORM CHASER

&&

EVENT NUMBER HGX1900012

41

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
615 PM CDT SAT APR 06 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0611 PM     HAIL             GRAPELAND               31.49N  95.48W
04/06/2019  E2.75 INCH       HOUSTON            TX   PUBLIC

0611 PM     FUNNEL CLOUD     GRAPELAND               31.49N  95.48W
04/06/2019                   HOUSTON            TX   PUBLIC

&&

EVENT NUMBER HGX1900013
EVENT NUMBER HGX1900014

41

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
617 PM CDT SAT APR 06 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0609 PM     HAIL             10 SSW NORMANGEE        30.90N  96.18W
04/06/2019  E1.75 INCH       MADISON            TX   TRAINED SPOTTER

&&

EVENT NUMBER HGX1900015

41

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