Funnel Cloud in Texas, July 14, 2019

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1026 AM CDT Sun Jul 14 2019

.UPDATE...
Satellite showing clouds associated with Barry wrapping around
from the NE and cloud cover over coastal counties associated with
impressive thunderstorm complex...MCS...off the SE TX coast.
Lightning rates have been high...cloud tops cold...warranting
special marine marines for most of the morning. In between these
cloud areas...abundant sunshine. Its in these mostly sunny areas
expect thunderstorm to develop this afternoon from destabilization
and vertical motion associated with direct thermal circulation set
up by differential radiative heating.

Model differences continue with handling of this band of storms
once it does set up...with many of the convective allowing models
generating a broken line which diminishes overnight...then refires
on Monday with relatively modest rainfall amounts. TTU WRF and
12Z HRRR fall into this camp. A few of the runs...especially high
resolution NMM WRF...a little more bullish in intensifying that
band of thunderstorms tonight into tomorrow...with higher rainfall
totals. Certainly something to continue to evaluate...watch for
through Monday for the potential of this band of more significant
rain but by no means a sure thing. We are confident of at least
scattered thunderstorms in this band however.

Reilly

&&

.PREV DISCUSSION /Issued 643 AM CDT Sun Jul 14 2019/...

.SHORT TERM...[Today through Tonight]...
A band of showers and thunderstorms associated with Barry, is
continuing to move southeastward across the Gulf waters this
morning. Gusty winds over 35 knots and waterspouts are possible
within this band of convection. Otherwise, all appears quiet inland
with temperatures as of 3 AM siting in the upper 70s to low 80s and
dewpoints in the 70s. The best chance for showers and thunderstorms
this morning should remain along the coast and over the Gulf waters.
Coverage in convection will creep further inland through the
afternoon and into the evening hours though, and heavy downpours and
gusty winds associated with stronger storms will become more of a
concern.  The Weather Prediction Center has outlooked a portion of
SE TX under a slight risk for excessive rainfall, across eastern
Matagorda, through southern Fort Bend and Harris, and for much of
Liberty County and southward. Short term guidance such as the NMM
and TT WRF, show a band developing over the coastal counties during
the afternoon, which then builds and shifts northward into the
evening and overnight hours, impacting the second tier of counties
inland. Over the past few days, the NMM has not initialized well but
the TT WRF has, which does lead to some concern. At this time,
rainfall totals for today and into Monday morning look to range
between 1 to 3 inches over the area highlighted in a slight risk by
WPC, but isolated higher amounts could be possible. Upper level jet
dynamics and mid-level frontogenesis values also look favorable for
the potential for heavy downpours over the next 24 hours along this
axis of convergence. Additionally, precipitable water values should
increase to 1.8 to 2.0 inches over SE TX by this afternoon, with the
best moisture contained along the coast. We will need to keep a
close eye on trends in rainfall rates and accumulations if this band
does indeed develop and shift inland late this afternoon and into
the evening. Otherwise, with partly cloudy skies becoming mostly
cloudy later this afternoon, high temperatures will tap out in the
upper 80s to low 90s today, with low temperatures tonight falling
into the low 70s to 80s area wide.

Hathaway

.LONG TERM...
Ongoing precipitation from Sunday night will end by mid/late
morning before daytime heating triggers scattered afternoon
showers and storms in the afternoon. Am getting increasingly
concerned that a band feeding into "Barry" will become established
somewhere across the southern/coastal portions of the CWA. HiRes
guidance initialized well and the NMM and TT WRF both show a band
setting up from Ft Bend, across southern Harris into northern
Galveston counties between 03-06z Monday and continuing through
about 15z Monday. If this occurs, some of the rainfall totals
could be heavy by Monday morning with some of the HiRes models
hinting at 3 to 5 inches of rain early Monday morning with even
higher totals to the NE across Chambers county. Still not
completely confident on where/when any convective banding will
form but favorable jet dynamics, a weak surface boundary and high
PW values seem to support the HiRes guidance. Will stay with the
high end chance PoPs for now because still not certain where this
band will develop. During the afternoon, convection should spread
out across the CWA with favorable jet dynamics, convective temps
near 90 and no capping evident in forecast soundings.

Will keep a slight chance of PoPs for Tues/Weds as PW values
remain between 1.80 and 2.00 inches but capping begins to increase
as 850 temperatures begin to warm. Global models still show some
light QPF over the extreme SE part of the CWA Thu/Fri but an
expanding 500 mb over the southern plains will likely keep most of
the area dry and hot. Heights build to 595 dm over OK and 850
temps warm to around 22 C. Looks like next weekend will be very
warm and dry with temperatures in the mid/upper 90s and heat index
values between 105-110 degrees. An inverted upper trough will
push west early in the following week undercutting the ridge and
could bring some showers back to the area a week from Mon/Tue. 43

.AVIATION [12Z TAF Issuance]...
Tricky TAF package, with low confidence in the placement of a band
of showers and thunderstorms that should develop this afternoon
before potentially redeveloping and pushing further inland this
evening. Mostly VFR conditions this morning with SCT025 decks
occasionally going BKN at isolated sites. Winds are light and
variable, but should turn more out of the southwest through the
afternoon and into the evening hours at IAH and terminals
southward. Most of the convection should be contained to the coast
in the early afternoon before spreading inland by late afternoon
to early evening. Anticipate a break in the precipitation before
redevelopment occurs along an axis of convergence this evening and
into the overnight hours. Short term guidance shows most of the
action at terminals as far north as IAH. The timing and placement
of this band can vary in upcoming runs of short term guidance, so
anticipate changes in the forecast.

Hathaway

.MARINE...
A band of showers and thunderstorms is continuing to develop and
move to the southeast across the Gulf waters this morning. Gusty
winds, heavy downpours, and waterspouts will be possible in this
line of convection. A Small Craft Advisory remains in effect across
the Gulf waters this morning. Moderate offshore flow will turn more
out of the southwest through the morning hours. Convection will be
possible over both bays and the Gulf waters through at least Monday
morning. Winds and seas will be locally higher in and around these
bands of precipitation. Small craft will likely need to exercise
caution through Tuesday, when light to moderate south to
southeasterly flow returns.

Hathaway

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL)  92  75  95  77  96 /  20  20  30  10  10
Houston (IAH)          93  78  94  79  95 /  40  70  50  20  20
Galveston (GLS)        90  81  90  83  90 /  60  70  50  30  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...None.
GM...Small Craft Advisory for winds until 10 PM CDT this evening for
     the following zones: Coastal waters from High Island to
     Freeport TX out 20 NM...Waters from High Island to Freeport
     TX from 20 to 60 NM.

     SMALL CRAFT SHOULD EXERCISE CAUTION until 5 PM CDT this
     afternoon for the following zones: Waters from Freeport to
     Matagorda Ship Channel TX from 20 to 60 NM.

&&

UPDATE...18