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Area forecast discussion
National Weather Service Houston/Galveston Texas
657 am CDT Mon may 29 2017

Aviation...
still some stratiform rain and embedded showers and thunderstorms
going on west southwest of sgr/lbx this morning likely in response
to the mesoscale convective system moving east through the northwest Gulf. Ceilings of 200
ft briefly possible around cll/uts/cxo otherwise mainly VFR.
Showers should pop up late this morning around the area and
transition over to thunderstorms and rain around noon or a little later. Low
confidence on where specifically so will vcsh/thunderstorms in the vicinity it for now.

Second issue is gradient wind event near the coast with meso-high
over the far coastal waters that should subside in the next couple
of hours.
45
&&

Marine...
another update to hoist Gale Warning for the Gulf waters and Small Craft Advisory
for bays as gradient wind event roars away...by 15z expect winds
to have dropped off dramatically from the current gusts of 35-45
knots.
45



&&

Previous discussion... /issued 537 am CDT Mon may 29 2017/

Marine...
meso-high driving gradient winds across the coastal waters and
into the coast and bays. Winds of 20-30kts gusts to 40 for the
next few hours. Winds should weaken as storms well offshore
weaken. Will have to watch comma head rotating in from the west
and could clip or aggravate the already strong winds as it pushes
east. Have hoisted Small Craft Advisory for all waters through 10 am and special
marine warnings through 7 am.
45

Previous discussion... /issued 419 am CDT Mon may 29 2017/

Discussion...
light to moderate rainfall lingers across southeast Texas this
morning behind an outflow boundary that has since pushed off the
Upper Texas coast. Regional radar mosiac shows most of the
thunderstorm activity this morning relegated to the western Gulf
of Mexico, with an expansive thunderstorm complex stretching from
Corpus Christi to Harlingen slowly pushing to the east.
Extrapolation of current storm movement places this complex into
the western waters sometime between 5 and 7 am CDT. At least
through the morning hours, this complex will be the primary driver
for rain chances for the region as its parent shortwave trough
lifts towards the region, pushing the complex and associated
surface low/mesoscale convective vortex into it. What remains to
be seen at this time is how far north rain chances will extend
inland this morning as the outflow approaching the south Texas
thunderstorm complex may result in enough low level convergence
off the coast to block inflow and cut off rain chances farther
inland. With mid and upper level steering flow from the southwest
concerned that there may be some expansion or movement to the
northeast into the Matagorda Bay area and have maintained 60-70
pops for this morning as a result. However, if this complex
appears to remain offshore an update may be needed later this
morning to lower rain chances.

With most activity along the coast and across the waters early this
morning, expect to see at least a brief break in rain chances but
daytime heating will result in scattered shower and thunderstorm
development across the region mid to late morning and into the
afternoon. Expect greatest coverage to occur along several of the
remnant boundaries draped across the region. Surface analysis
reveals that yesterday's cold front remains stalled well north of
the Interstate 10 corridor, stretching from San Antonio to Hearne
to Athens. The kgrk radar this morning is also showing several
moisture "fine lines" across the Brazos Valley, indicative of
remnant outflow boundaries from last night's storms. Other
unidentified boundaries may also exist farther south of these
locations. Limited shear (less than 20 knots) present through
early afternoon and much less steep lapse rates than yesterday
(5.5-6.5 c/km) will result in a much lower severe weather threat
today, but with some dry air present between the surface and 600
mb on forecast soundings cannot rule out gusty winds in stronger
convection. 1.7-2 inch precipitable water values today (higher
than the 75th percentile for this time of year) will also mean the
locally heavy rain threat will continue, especially along any of
the aforementioned boundaries. Subsidence from the passing
shortwave trough should result in another break in the rain by
this evening and into tonight, with diurnal heating and
precipitable water values in the 1.6-1.8 inch range on Tuesday
resulting in scattered to numerous showers and thunderstorms
capable of locally heavy rain. Expect highs to range in the upper
70s to low 80s today, warming into the low to mid 80s on Tuesday.

Periods of showers and thunderstorms will continue across the
region Wednesday into the weekend as a series of disturbances now
near the Gulf of Alaska on early morning water vapor imagery drop
to near Baja California and translate east across Texas. Elevated
precipitable water values in the 1.6-1.9 inch range will mean the
threat for locally heavy rainfall will persist each day, with rain
chances likely being enhanced during the daytime hours from
heating. Expect high temperatures to remain in the low to mid 80s
through the end of the work week. Dry weather may not return to
the forecast until early to mid next week as shortwave ridging
attempts to build into the region.

Huffman

Marine...
stormy weather this morning over the coastal waters. Outflow
pushed southward through the region bringing gusty conditions
(20-45kt) and has collided with boundary offshore and being
intercepted by incoming mesoscale convective system from crp area. Hoisted a Small Craft Advisory through
10 for these strong winds and elevated seas but by 8-10 am expect
that conditions should be improving except for all but the far
coastal waters where storms will probably be the most active-or
just south of there...will need to keep an eye out for meso high
developing and ramping up winds.

Otherwise easterly winds becoming southeasterly this afternoon
and overnight gradually increasing to 10 to 15 knots and then
persisting through Saturday. As moist to very moist conditions
flowing into and through the region expecting showers and
thunderstorms to remain a threat.

European model (ecmwf) still painting the scenario of fairly intense low pressure
system developing in the western Gulf (saturday) and slowly moving
to near Galveston (monday morning) which would have big impacts
on the current forecast. Have trended the forecast toward the GFS
but will be watching closely to see of the GFS or the European model (ecmwf) blink.
45

&&

Preliminary point temps/pops...
College Station (cll) 80 69 84 69 85 / 40 30 40 20 50
Houston (iah) 81 70 84 71 85 / 50 30 60 30 50
Galveston (gls) 80 74 81 76 83 / 60 50 60 30 50

&&

Hgx watches/warnings/advisories...
Texas...none.
GM...Small Craft Advisory until 11 am CDT this morning for the
following zones: Galveston Bay...Matagorda Bay.

Gale Warning until 11 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.

&&

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