APRIL 2019: Warm & Muggy WX to End The Month

[tireman4]

Hazardous Weather Outlook..

[tireman4]

006
FXUS64 KHGX 221700
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1200 PM CDT Mon Apr 22 2019

.AVIATION...
Any residual MVFR ceilings will likely mix out this afternoon. SE
winds will increase a bit and an occasional gust will be possible.
MVFR ceilings are expected to redevelop tonight but some conflicting
data between the models. Leaned toward a blend between the previous
TAF and the NAM/GFS forecast soundings. Conditions should again
mix out on Tuesday afternoon. Moisture still looks a bit too
scarce to mention VCSH with a very dry layer noted between 850 and
700 mb. 43

&&

.PREV DISCUSSION... /ISSUED 941 AM CDT Mon Apr 22 2019/

DISCUSSION...
Still on track for a partly/mostly cloudy day across much of Southeast
Texas with surface high pressure off to our east and a continuation
of the onshore flow. Moisture levels will continue to be on the rise,
but planning on no changes to the current package that keeps us rain
free until tomorrow when very low chances come back into the forecast.
Wednesday afternoon through Thursday morning is still looking like
our next best chance of stormy weather (see discussion below). 42

PREV DISCUSSION... /ISSUED 421 AM CDT Mon Apr 22 2019/

DISCUSSION...
Partly to mostly cloudy skies across the region early this morning
with some cirrus passing through. Closer to the surface, onshore
flow is starting to moisten under the cap. Not expecting much in
the way of precip today...just mcldy skies with highs around 80.

Models are showing some weak disturbances embedded in a developing sw
flow aloft moving across the area tomorrow. Fcst soundings are showing
increasing saturation above 600mb, though with a fairly dry
subcloud layer in place it`s questionable whether any precip
generated will be able to make it to the ground or not. Some of
the guidance seems to hint at that possibility so went ahead and
threw in some 20-30% POPs for Tues.

Shra/tstm chances increase from wnw to ese Wednesday afternoon
through Thursday morning as large scale lift increases from the
approaching upper trof. Frontal boundary sagging into cntl & north
Texas will eventually become a focus for convection during the day
and overnight Wed as it sags into and across se Tx. Surface low/wave
looks to develop along this boundary and track northeastward. At
this time, the majority of guidance takes it`s trajectory (and
overall heavy rain threat) generally northwest of our CWA...but
still needs to be watched closely for any progged southward
deviations in the next few days. Assuming clouds don`t hamper
heating too much, the atmosphere becomes increasingly unstable
thru the day especially w/sw areas. LFQ of 110-130 jet noses into
the area aiding in upper diffluence. Appears the main wx threat
for the HGX CWA will be the possibility of some severe wx
Wednesday night with hail/winds being primary threat.

Prefrontal trof should push off the coast around or shortly after
sunrise Thursday followed by the front itself. There will probably
be some lingering wrap around cloudiness and showers, but that
will eventually move out of the area Thursday evening. As we head
into the weekend, a building ridge will bring msunny skies and
warmer temps to the area. 47

MARINE...
A generally moderate (to occasionally strong) onshore flow is expect-
ed to persist these next several days. We`ll continue to see periods
of elevated winds/seas through mid week (especially for the offshore
waters) and either SCEC or SCA flags will likely remain posted these
next few days. This pattern should prevail until late Weds night to
early Thur morning when the next upper level storm system and its as-
sociated cold front moves through the area. Widely scattered showers
and thunderstorms are possible the next few days as well, but a line
of more organized activity will be accompanying the front when as it
moves ito the Gulf waters. A brief period of elevated offshore winds
is expected behind the front early Thurs, but high pressure building
quickly into the area will allow for a more light/moderate northerly
flow through rest of the week. As the high moves off to the east, we
will be seeing the gradual return of onshore winds over the weekend.
41

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 81 66 79 65 77 / 0 0 30 20 60
Houston (IAH) 80 67 78 66 80 / 0 0 30 10 30
Galveston (GLS) 76 70 76 69 77 / 0 0 10 10 20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION through late tonight 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...42
Aviation/Marine...43

[Cpv17]

Models are really backing off on rain now. Might not even get an inch out of this anymore

Map above shows widespread 2 inches...?

Both the GFS and Euro show less than an inch across SETX.

[srainhoutx]

The Weather Prediction Center in their afternoon 3 Day QPF chart suggests a general 1 to 2 inches are possible across portions of the SE Texas Region. Lesser amounts possible down near Matagorda Bay into Wharton.

[Cromagnum]

A little rain is okay this week, don't need a flood. Just started enclosing a patio and don't need a swimming pool before the windows go in

[Katdaddy]

A mostly cloudy day ahead with some showers possible. Radar shows some light rain and few isolated heavier showers moving into SW portions of SE TX this morning. The potential for heavy rain some strong to severe thunderstorms will be possible across SE TX Wednesday afternoon through early Thursday morning.

[Houstonkid]

Looks like they shifted the slight risk to the west a considerable bit.

[tireman4]

12
FXUS64 KHGX 231033
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
533 AM CDT Tue Apr 23 2019

.DISCUSSION...
Not too many changes planned with the upcoming forecast as we are
still looking for increasing rain chances the next couple of days
out ahead of and with the passage of a strong upper trof from the
west. The highest chances for precipitation...and possibly severe
weather for SE TX will be from Weds evening on through early Thur
morning.

Isolated showers/thunderstorms developing out to the W/SW are ex-
pected to impact western portions of the CWFA later this morning.
These storms appear to be courtesy of an embedded disturbance (in
the SW flow aloft) moving up from under the main upper trof still
out west. The activity should move out to the E/NE by this after-
noon with warm/humid conditions continuing. Did keep with slight-
ly lower POPS for tonight as models as not indicating much by way
of short-wave energy, but would not be too surprised if there was
some very isolated WAA-type showers overnight/early Weds morning.

The main forecast focus looks to be the aforementioned time frame
from Weds evening through early Thur morning. A line of strong to
possibly severe storms developing over SouthCentral TX during the
afternoon on Weds is expected to move into SE TX by that evening.
While the track of this vigorous positively tilted upper low will
be just to our north, a favorable location of the southern stream
jet along with the increased PWs and steep lapse rates are point-
ing to the continued development of strong/possibly severe storms
as this line moves across the CWA. Hail and strong damaging winds
look to be the primary threat. We`ll also likely see fairly wide-
spread rainfall with this system. Rain totals should average from
1/2 to 1 inch with isolated totals of 2 to 4 inches possible with
training storms.

Drier/slightly cooler weather will be on tap for Fri (in the wake
of the associated front), but we could see some rather warm temp-
eratures for the weekend. Progs of a deep SW flow at the lower to
mid levels are hinting at highs of mid and possibly upper 80s for
this time period. 41

&&

.MARINE...
The southeasterly flow will continue today and will be fluctuating
between 12-14 knots early this morning increasing to 13-17z late
this morning and afternoon. SCEC was already in effect and have
extended it through early evening. Winds should be increasing this
afternoon and with seas already 4-6 feet early may see a brief
decrease before responding to the increased winds this afternoon. As
the upper trough approaches and winds back slightly will like see an
increase in tide levels Wednesday. Rain chances for the coastal
waters increasing throughout the day Wednesday with slightly
stronger winds in the western waters. Gusty southerly winds ahead of
the cold front Wednesday night/Thursday morning with the cold front
pushing off the coast Thursday morning. Could see some strong
thunderstorms with the frontal passage. Winds in the wake of the
front look to be primarily moderate westerly until early Friday
morning and may reach SCA early Friday as cooler air arrives and
pressures fall over the Coastal Waters of Louisiana. Light and
variable winds Friday night/Saturday morning.

45
&&

.AVIATION...
Mix of MVFR/IFR/VFR ceilings across the area with these spreading
further north early this morning. The lowering trend should come to
an end around 13-14z and with the warming start to rise. A
disturbance coming in from the southwest has helped to develop a
couple of thunderstorms near VCT with the steering flow bringing
them northeast. A few of the HRRR runs indicated these could show
some life becoming a little more organized around 14-16z with
possible impacts for SGR/HOU/LBX area - will be keeping a close eye
on these and may be adding VCTS to these for a few hours this
morning. VFR ceilings this afternoon but these should be short lived
as ceilings lower to MVFR by early evening and some IFR will be
possible after midnight. Thursday 03-12z thunderstorms across the
Metro terminals.
45
&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 79 64 77 62 75 / 20 20 70 90 30
Houston (IAH) 79 65 79 65 78 / 20 10 40 90 40
Galveston (GLS) 77 69 77 68 76 / 10 10 20 90 40

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION through 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.

&&

$$

[tireman4]

Hazardous Weather Outlook

[tireman4]

Forecast Tuesday April 23, 2019

[srainhoutx]

Tuesday morning weather briefing from Jeff:

Another round of severe weather and heavy rainfall will move across SE TX Wednesday evening into Thursday morning.

A weak disturbance in the SW flow aloft will likely produce a few showers over the area this morning before moving east of the region by early afternoon.

An upper level trough over the SW US will move east across TX tomorrow while a slow moving cool front sags southward over NC TX and into SE TX Wednesday evening. Low level moisture is already returning with dewpoints well into the 60s over much of the region this morning. Moisture will continue to increase over the next 24-36 hours with PWS peaking near 1.9 inches Wednesday evening. Air mass on Wednesday will become increasingly unstable with modest surface heating, but capping in the mid levels should preclude much in the way of thunderstorms. Will likely see a few scattered warm air advection type showers move from the Gulf northward across the area.

Main event comes Wednesday night as a strong upper level disturbance combined with good dynamics aloft, high moisture levels, and a surface front move across the region. Expect a cluster or line of strong to severe thunderstorms to develop Wednesday afternoon over SC TX and move into SE TX Wednesday evening. Main threats will be damaging straight line winds and large hail. SPC has the western and southwestern portions of our area in the Day 2 slight risk.

Other threat will be heavy rainfall with a slow moving line of thunderstorms into Wednesday morning. Widespread rainfall amounts of 1-2 inches appear likely with isolated totals of 3-4 inches where any cell training occurs. Grounds are starting to become wet across the region…especially north of I-10 from the recent rainfall and the middle Trinity and Navasota Rivers are in minor flood, so additional widespread rainfall will likely cause additional rises on area rivers.

SPC Day 2 (Wednesday) Severe Weather Outlook:

[/i]

[tireman4]

From the National Weather Service West Gulf River Forecast Center

[stormlover]

What does this mean

[Belmer]

After looking at the morning model runs, not surprised the SPC has decided to expand the 'Slight Risk' further to the east to include SETX. Discussion is below...

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1224 PM CDT Tue Apr 23 2019

Valid 241200Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
SOUTHERN AND CENTRAL TEXAS INTO FAR SOUTHWEST LOUISIANA...

...SUMMARY...
Thunderstorms associated with large hail, wind damage and a tornado
threat are expected to develop across parts of southern and
southeast Texas into far southwest Louisiana on Wednesday and
Wednesday night.

...TX and LA Vicinity...

Convection will likely be ongoing Wednesday morning from western
into north-central TX on the cool side of surface cold front. This
activity is not likely to be severe during the morning hours. By
afternoon, additional thunderstorm development is expected in the
warm sector across parts of the central TX when stronger ascent
associated with the eastward advancing upper low overspreads the
region. Southeasterly low level flow will maintain Gulf moisture
ahead of the surface boundary, and dewpoints in the mid 60s to low
70s F are already in place. While cloud cover may inhibit
development through the morning hours, by afternoon, temperatures
warming into the upper 70s and low 80s beneath steepening midlevel
lapse rates should result in 1000-2000 J/kg MLCAPE from the Rio
Grande Valley toward the Upper Texas Coast. Semi-discrete supercells
may develop initially, posing a threat for large hail and damaging
wind gusts. A tornado threat is also possible, given backed low
level flow and maximized SRH in the vicinity of the frontal boundary
and weak surface low.

Convection is expected to grow upscale during the late
afternoon/evening across central TX and track eastward toward
southern portions of the Sabine River Valley/southeast LA overnight.
Latest model guidance suggests a 35-45kt southerly low level jet
will develop ahead of the bowing segment, with deep layer shear,
adequate instability and abundant boundary layer moisture more than
capable of maintaining eastward progression of the line. Thus, an
attendant threat for damaging wind gusts and possibly a QLCS tornado
will extend into southeast TX and far southwest LA overnight.

...MAXIMUM RISK BY HAZARD...
Tornado: 5% - Slight
Wind: 15% - Slight
Hail: 15% - Slight

..Leitman.. 04/23/2019

[Cpv17]

Blahhh

[jasons2k]

Looks like a dry slot in there. Something to watch.

[Rip76]

Looks like a dry slot in there. Something to watch.

[Katdaddy]

Time to be weather aware again. An active weather day and night ahead across a large portion of TX. Strong to severe thunderstorms with heavy rain and flash flooding have been moving across the Hill Country, NW TX, N Central and N TX overnight. The strong to severe thunderstorms with heavy rain will move across Central and S Central TX this morning through the afternoon which will then progress across SE and E TX tonight through early Thursday morning.

[srainhoutx]

The Weather Prediction Center has issued a Slight Risk for Excessive Rainfall for today. Areas along and North of the I-10 Corridor appear to appear to have the best chances of seeing some heavy rainfall this afternoon into the overnight hours.

[tireman4]

Definitions of Severe Weather