Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 191749

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1249 PM CDT Fri Oct 19 2018

.AVIATION...[18Z TAF Issuance]

Surface analysis now showing the warm front starting to edge
inland along the coast with winds starting to turn to the SE.
Shower activity has increased towards Matagorda Bay and as this
activity moves inland it should increase in coverage and
intensity. HRRR/WRF/RAP13 seem to be developing this activity
inland and latest SPC Mesoanalysis does show some surface based
CAPE indicating some destabilization. For the TAFs, biggest issue
will be seeing what convection develops but have enough confidence
for at least VCTS at KSGR and KLBX this afternoon. This may need
to be expanded into KIAH/KHOU but will wait to see. Ceilngs will
be an issue and it looks like a return to MVFR ceilings will have
sooner than later. MVFR ceilings should hold on overnight as a
frontal boundary pushes into the area. Models indicate the
possibility of IFR ceilngs by Saturday morning. This very well
could be real given the frontal boundary but models also tend to
be more aggressive with IFR forecasting. For now will mention a
scattered 800ft deck for all TAFs. Ceilings will be slow to
improve tomorrow morning into the afternoon.



.PREV DISCUSSION... /ISSUED 1052 AM CDT Fri Oct 19 2018/


Near term model trends have an area of thunderstorm activity that
develops this afternoon mainly along the I-69/US 59 cooridor from
Sugar Land to Wharton. Essentially just pick a model (HRRR/WRF
ARW/WRF NMM/RAP/Tx Tech WRF) and you will see by 21Z this
afternoon a cluster of storms. But why. Surface analysis shows the
old frontal boundary which is more of a warm front now is now
right along the coast. Surface dewpoints have increased along the
coast especially KBYY and GOES 16 PW imagery shows a plume of 2
inch precipitable water moving up from the south. SPC Mesoanalysis
at 925mb and 850mb shows strong low level flow in this area with
moisture transport vectors oriented inland off the Gulf. This
should help push the warm front further inland and open up the
warm sector over the coastal areas of SE Texas. High temperatures
may now reach the low 80s or close to convective temperatures
today (low/mid 80s based on CRP sounding) for surface based
convection. With these trends in mind, forecast has been udpated
for higher rain chances and we will need to look for locally heavy
rainfall this aftenroon in these areas. With fairly saturated
grounds, there will be a localized flood threat to monitor through
the evening hours.



College Station (CLL)      71  61  69  57  69 /  40  70  50  10  10
Houston (IAH)              79  67  74  60  71 /  50  40  50  10  10
Galveston (GLS)            79  74  78  66  72 /  50  40  50  30  10


     afternoon for the following zones: Coastal waters from
     Freeport to Matagorda Ship Channel TX out 20 NM...Coastal
     waters from High Island to Freeport TX out 20 NM.

     Small Craft Advisory until 1 PM CDT this afternoon 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.

     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.



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