May 2017: Memorial Day/End Of May Outlook

General Weather Discussions and Analysis
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srainhoutx
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I just emptied 1.40 inches of overnight rainfall out of my gauge. The Texas Tech 3Km WRF is suggesting the complex of storms near Corpus will begin growing upscale and pushing inland with some embedded heavier showers and storms early this afternoon and organize into line of storms across portions of the Hill Country into College Station and on East. Another MCS looks to roll out of Mexico into S Central Texas overnight and push generally East into our Region before some drying occurs later on Tuesday into early Wednesday. In the June Topic I have mentioned the ECMWF solution overnight and the potential for additional heavier rainfall later this week into the weekend.
05292017 06Z TT WRF 10 dom_2km_sfc_dbz_f10.gif
05292017 06Z TT WRF 11 dom_2km_sfc_dbz_f11.gif
05292017 06Z TT WRF 12 dom_2km_sfc_dbz_f12.gif
05292017 06Z TT WRF 13 dom_2km_sfc_dbz_f13.gif
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srainhoutx
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Update from Jeff regarding the Coastal Flooding potential:

A large thunderstorm complex with intense meso low formation over the NW Gulf of Mexico is resulting in strong onshore winds across the coastal waters with several hours of winds gusting over 40mph. This is resulting in a very rapid rise in coastal tides to as much as 3.5-4.0 ft above normal levels.

A coastal flood advisory is in effect until early this afternoon for Chambers, Galveston, Brazoria, and Matagorda Counties and a coastal flood warning is in effect for Calhoun County where flooding on the west side of Matagorda Bay is currently in progress. As the meso low begins to weaken and shift NE along the coast today this should help to weaken onshore winds and gradually reduce the coastal flooding in progress by mid afternoon. Until that time water levels will likely reach dune bases along the Gulf beaches and may overwash portions of Bolivar and the west end of Galveston Island.
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srainhoutx
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A bit drier weather today into early tomorrow as a Coastal trough S of Louisiana (remnants of yesterday morning's MCV that exited into the NW Gulf near Corpus) moves on East. Upstream near the Baja Peninsula, the next upper air disturbance is heading our way and should see a return of scattered showers and storms tomorrow afternoon into Thursday. Further upstream about a 1000 miles West of Northern California, another upper air feature is heading East in the zonal flow. We will tough more on that potential rain maker in the June Topic as well as some increase in deep tropical moisture surging our way from the NW Caribbean and the Eastern Pacific where 91E is festering South of the Gulf of Tehuantepec and may have a chance to spread additional tropical moisture our way into the weekend.

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tireman4
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874
FXUS64 KHGX 301126
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
626 AM CDT Tue May 30 2017

.AVIATION...
A weak coastal trough over the Gulf is progged to weaken this
morning with NE winds becoming ESE by afternoon. Winds should
remain light as the gradient remains weak today. Showers have
arrived at the coast and some expansion inland is expected this
morning. Convective temps are in the lower 80s so a little
heating should get things started. Fcst soundings differ with
regard to cloud cover, cigs and rain chances with the NAM looking
more aggressive. A weak disturbance early Wednesday morning could
bring more shra/tsra to coastal areas prior to 12z. 43

&&

.PREV DISCUSSION... /ISSUED 400 AM CDT Tue May 30 2017/

DISCUSSION...
Marine observations shows a coastal trough axis extending from
near Buoy 42035 south-southwest towards Buoy 42019. Regional radar
mosaic has shown associated shower and thunderstorm activity
spreading into coastal Louisiana for much of the night, but
a few of these showers have been able to creep into the eastern
waters early this morning. As this trough continues to lift
towards the northeast through the day, expect to see showers (and
possibly a few thunderstorms) push inland into Southeast Texas in
response. Based on the anticipated trajectory of the coastal
trough and CIRA layer precipitable water imagery showing a plume
of PWATs in the 1.6-1.9 range nosing east of the Sabine Pass,
anticipate highest rain chances to materialize east of Interstate
45 today (30-40 PoPs). Will have to keep an eye on the
southeastern counties in case the trajectory of the coastal low
results in rainfall focusing across these areas possibly resulting
in an isolated minor flood threat.

Drier conditions to the west of Interstate 45 (CIRA PWATs 1-1.2
inches this morning) should limit overall coverage but cannot
rule out an isolated shower or storm as convective temperatures in
the low to mid 80s are reached this afternoon, especially along
an increasingly diffuse frontal boundary stretching from near
Austin to Hearne to Texarkana. Otherwise, patchy fog early this
morning outside of the Houston metro is expected to lift by mid-
morning with highs in the mid to upper 80s today and partly cloudy
skies.

Generally dry conditions are expected tonight as the coastal
trough lifts inland, but deeper Gulf moisture (now located near
Brownsville on aforementioned CIRA imagery) is expected to surge
northward in its wake. This will result in isolated showers and
thunderstorms returning to the coastal waters by early Wednesday
morning with this moisture pushing inland during the day. Better
moisture tomorrow (PWATs rising back into the 1.6-1.9 range
areawide) should allow for daytime heating to produce an least
scattered shower and thunderstorm coverage inland as highs rise
into the mid 80s, with stronger cells capable of heavier
downpours and possibly some gusty winds as forecast soundings show
a bit of an inverted-V signature/dry subcloud layer. Storms will
be moving, but with mean winds only around 10-15 MPH storm motions
may be slow enough to contribute to a localized minor flood
threat. Activity should diminish with loss of heating tomorrow
evening, but early morning water vapor imagery shows a shortwave
trough near Baja California that will continue to translate
eastward tonight and Wednesday and approach the region Wednesday
night.

The approaching shortwave trough will result in rain chances
increasing from west to east across the region Wednesday night
into Thursday as the right rear quadrant of an associated 70 knot
upper level jet moves across the region. Forecast soundings show
moisture continuing to increase during this time as a weak 20 knot
low level jet sets up, allowing precipitable water values to
exceed 1.8 inches. This should result in scattered to numerous
showers and thunderstorms developing across the region Wednesday
night into Thursday. As noted in the previous forecast, no
significant surface boundary or focusing feature appears to be
present as today`s remnant frontal boundary should have modified
considerably or washed out by this time. However, convection
during the day Wednesday may leave smaller outflow boundaries that
could provide a focus for development. Rain chances are expected
to taper off Thursday night behind the departing shortwave trough,
before daytime heating again on Friday results in scattered
showers and thunderstorms again. Highs through the end of the week
are forecast to remain in the low to mid 80s.

Another shortwave trough is forecast to drop down the California
coast and reach Texas by Saturday, with increasing lift ahead of
this feature again resulting is scattered showers and
thunderstorms through the weekend. Medium range guidance is
somewhat inconsistent on the timing of this shortwave, however,
and rain chances may linger into the beginning of next week before
it clears the region.

Huffman

MARINE...
A coastal trough over the western Gulf has tightened the gradient
and wind speeds have increased. A SCEC is in effect through the
early morning. The trough is expected to weaken and wind speeds
should decrease by late morning. Onshore winds will develop as high
pressure remains over the eastern Gulf and low pressure persists
over the Rockies. A light to occasionally moderate onshore flow will
prevail through the end of the week. The flow will increase toward
the weekend as a deepening area of low pressure over SE CO moves
across the southern plains. Showers/storms will be possible over the
Gulf waters through the week and mariners should prepare for some
variable/gusty winds with the stronger storms. 43

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 86 68 86 70 83 / 20 10 40 40 60
Houston (IAH) 85 70 86 72 84 / 30 10 40 40 60
Galveston (GLS) 83 77 84 76 83 / 40 20 20 40 70

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 8 AM CDT this morning
for the following zones: Coastal waters from Freeport to
the Matagorda Ship Channel out 20 NM...Coastal waters from
High Island to Freeport out 20 NM...Waters from Freeport to
the Matagorda Ship Channel from 20 to 60 NM...Waters from
High Island to Freeport from 20 to 60 NM.

&&

$$

Discussion...31
Aviation/Marine...43
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DoctorMu
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Glad areas south got a soaking. This weekend was largely a bust in the CLL area. Hoping for precip during the week...a bit wary though.

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GBinGrimes
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Wife and I were sitting out on porch Sunday evening watching a fantastic lightning show meandering in from the NNW and waiting for what was sure to be a good soaking. Kept watching the radar on phone and sure enough, the line kinda danced a jig in portions of Brazos, Robertson, Washington and Grimes counties and then reformed in earnest just south of 105. Weather is as amazing as it is frustrating.
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srainhoutx
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HGX Radar has been repaired and is up and running!
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jasons2k
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Good news on the radar! I've been watching the building convective complex west of San Antonio. It could push an outflow eastward across SE Texas later today/this evening. That may the boundary we need to set off some storms.
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jasons2k
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Area Forecast Discussion
National Weather Service Houston/Galveston TX
353 PM CDT Tue May 30 2017

.DISCUSSION...
Position of the coastal trof hasn`t really moved all that much
today. May see a few isolated cells prior to sunset, but should
see a quiet overnight period. The cluster of storms moving sse
across cntl Tx should remain west of the region, but`ll send some
debris overhead later this evening.

The coastal trof may edge a bit closer to the coast toward
morning, but will be in the process of washing out throughout the
day. Expect some iso/sct precip to develop across inland areas
with daytime heating.

Low levels of the atmos will moisten late Wed into Thurs ahead of
an approaching upper level disturbance forecast to move across
the area from the wsw. Increasing precip coverage can be expected
late Wed night and thru the day Thurs as this occurs. Most of se
Tx still appears looks to be positioned in a favorable jet position
for upper diffluence during the late night and early morning hours
so we`ll need to keep an eye out for some efficient rainfall. But,
unless a meso boundary emerges, we`ll be lacking a surface focus
many times needed to produce widespread heavy rain/ff issues.

Scattered, mainly diurnal precip can be anticipated thru the
weekend. We`ll be keeping an eye on deep moisture currently
situated on the southern Pacific coast of Mexico. Guidance
suggests this gets caught up in a southerly fetch into the the
western Gulf of Mexico ahead of a slow moving upper trof/weakness
this weekend into early next week. Whether the deepest moisture
reaches the Tx coast or remains further east is unclear at this
point.
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Katdaddy
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The threat of scattered thunderstorms will continue into the weekend:

Hazardous Weather Outlook
National Weather Service Houston/Galveston TX
414 AM CDT Wed May 31 2017

TXZ163-164-176>179-195>200-210>214-226-227-235>238-010915-
Austin-Brazoria-Brazos-Burleson-Chambers-Colorado-Fort Bend-
Galveston-Grimes-Harris-Houston-Jackson-Liberty-Madison-Matagorda-
Montgomery-Polk-San Jacinto-Trinity-Walker-Waller-Washington-
Wharton-
414 AM CDT Wed May 31 2017

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

.DAY ONE...Today and Tonight

Scattered showers and thunderstorms are expected today. Stronger
activity may be capable of brief heavy downpours.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Scattered to occasionally numerous showers and thunderstorms are
expected each day. Stronger activity may be capable of brief heavy
downpours.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.
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tireman4
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00
FXUS64 KHGX 311148
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
648 AM CDT Wed May 31 2017

.AVIATION...
Some brief IFR cigs possible near the Houston terminals early this
morning but conditions are expected to improve quickly. Convective
temps are in the lower 80`s today so daytime heating should
trigger scattered shra/tsra later today. Precip should end by
evening with generally VFR conds expected through 06z. MVFR cigs
possible between 06-09z in advance of another weak short wave.
Could get some showers prior to Thursday morning sunrise near the
coast as low level moisture increases over SE TX. 43

&&

.PREV DISCUSSION... /ISSUED 401 AM CDT Wed May 31 2017/

DISCUSSION...
A coastal trough remains located just off the Upper Texas coast
early this morning, with backed easterly flow in the vicinity of
this feature resulting in a few showers across the coastal waters
and along Bolivar Peninsula early this morning. Expect this trough
to continue to weaken through the day, with isolated showers
spreading across the coastal counties this morning and isolated to
scattered showers and thunderstorms developing farther inland
this afternoon as convective temperatures in the mid 80s are
reached. A few brief heavy downpours will be possible in stronger
activity this afternoon and evening.

Showers and storms may linger into the early evening hours before
dissipating with loss of heating. However, the passage of a 60-70
knot subtropical jet streak as a shortwave trough lifts out of
Chihuahua into the Texas/Oklahoma Panhandles looks to result in
another round of showers and thunderstorms developing across the
region overnight. Higher resolution and global model guidance
varies with the placement of this jet and, accordingly, where the
best dynamics will be located... which is offering some
inconsistencies on which areas will see rain (and how much).
Lowered rain chances slightly for the overnight period, but
continuing to advertise scattered coverage with the aforementioned
jet near the region. Should favorable jet dynamics set up over
the region overnight to encourage increased upper divergence/lift
over the region, this would help encourage the development of more
storms (and storms that are also more efficient rainfall
producers). Without any well-defined surface boundary and CIPS
analogs showing very little signal for high precipitation
amounts, think the most likely hazard tonight and over the next
few days will continue to be brief heavy downpours.

As a plume of deeper moisture (precipitable water values 1.7-2.0
inches on CIRA layer precipitable water imagery) located about 150
miles south of the Upper Texas coast pushes into the region
tomorrow as the coastal trough loses definition, expect rain
chances to persist inland during the day Thursday with scattered
to numerous diurnally driven showers and thunderstorms expected to
develop. Otherwise, another round of scattered diurnally driven
showers and thunderstorms are expected on Friday with highs in the
mid to upper 80s and lows in the 70s through the end of the work
week.

Another shortwave trough is forecast to drop down the California
coast from the northern Pacific this week, reaching northern
Mexico Friday. Energy ejecting ahead of this main disturbance
looks to reach the region on Saturday, possibly resulting in
more shower and thunderstorm coverage during the day than what the
region sees on Friday. Chances for showers and thunderstorms will
linger into Sunday as the main disturbance reaches Texas with
highs this weekend in the upper 80s and lows in the low to mid
70s.

Medium range guidance still offers differing solutions for when
this weekend`s main disturbance and an associated cold front will
arrive into the region, with the Canadian/GFS advertising the
cold front reaching the region next Tuesday and the European
maintaining the slowest solution with next Wednesday. Have kept
low rain chances (20 PoPs) in the forecast for the beginning of
next week as a result and temperatures near climatological
normals until better consistency is achieved.

Huffman

MARINE...
A weak coastal trough will persist today but the overall pressure
gradient has weakened. A light to occasionally moderate onshore
flow is expected today and tonight. Winds will gradually
strengthen tonight through Friday as low pressure in the lee of
the Rockies deepens. A weaker flow is expected late in the weekend
as the gradient relaxes ahead of a cold front. There are some
timing differences on when/if the cold front crosses the coastal
waters. The Canadian is the fastest and the ECMWF is the slowest
so leaned toward the GFS which was a bit of a compromise bringing
a weak front through on Monday and a second stronger front on
Tuesday. No tide issues expected for the next 5 days. 43

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 88 71 85 71 88 / 30 30 60 30 30
Houston (IAH) 87 73 85 73 87 / 30 40 60 20 50
Galveston (GLS) 86 77 82 78 83 / 20 40 50 20 40

&&

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

$$

Discussion...14
Aviation/Marine...43
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brooksgarner
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Hi Guys! Looks like more isolated to brief scattered activity this evening -- around commute time -- along sea breeze boundary. As for bigger rain chances, an storm complex could develop to our west and push through the area. HRRR advertises a passage to our north, but since this is all mesoscale driven, certainly is far from exact. In fact it could slam Houston causing flooding tonight, or it may not hold together.

Ingredients are once again in place, but subtle feature in the upper levels will seem to drive future nocturnal storm development. Pitfalls?

1) Mesoscale boundaries produced as outflow from evening storms set up in different spots. This could change storm evolution and initiation zone.

2) Upper disturbance swinging through may have more or fewer effects than believed.

3) Plume of moisture coming out of coastal south Texas produces offshore storms (off of Galveston), causing an area of subsidence, reducing our storm chances.

Fun!

-Brooks
Broadcast Met
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http://twitter.com/BrooksWeather
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jasons2k
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It doesn't look very promising for tonight, or even tomorrow going into to Friday. I just might end up without a single drop of rain during this much advertised "wet" week. I thought today was supposed to be the mother-lode. Guess not after all.
Cromagnum
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jasons wrote:It doesn't look very promising for tonight, or even tomorrow going into to Friday. I just might end up without a single drop of rain during this much advertised "wet" week. I thought today was supposed to be the mother-lode. Guess not after all.

Well in all fairness they did basically say "they don't know what it's going to do until it does it".
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100% chance of rain predicted, and yet.

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mcheer23
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Don't know where you got 100 from
Cromagnum
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mcheer23 wrote:Don't know where you got 100 from

Apps on my phone had it at 100% until it didn't happen and then it backed the chances down.
TexasBreeze
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It took all week to rain in the TomballSpring area. About 10 min worth. It has been a donut hole since Sunday night's storms.
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djmike
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Fyi... discussion has moved to the June thread...thanks
Mike
Beaumont, TX
(IH-10 & College Street)
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