Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 200941

Area Forecast Discussion
National Weather Service Houston/Galveston TX
441 AM CDT Thu Oct 20 2016

04Z surface analysis has the main cold front located roughly
along a Presidio to San Angelo to Wichita Falls line. A ragged
line of convection forming just ahead of this boundary, the type
of broken line convection that can be expected to reach our
northern reaches by the late morning hours. Although there will
be some error with the overall evolution (or timing) concerning
today`s frontal passage (e.g., mid to upper flow becoming more
parallel with surface front, location of the leading pre-frontal
trough), the main cold front will likely come through between the
mid to late morning hours up north and be off the coast by the
late afternoon. Precipitation coverage will consist of scattered
showers with isolated storm cells forming just downstream of the
approaching front north of the city, more coastal counties and
local water discrete cells moving north as they are caught up
within the onshore (in)flow pattern. In summary, due to the
progressive nature of this fropa, most have a high probability of
receiving under a half of an inch of precipitation, those closer
to the coast will pick up between a half of an inch and an inch of
rain. Today`s two main threats will be locally dense morning fog
impacting the rush hour with, if a poorly formed QLCS does push
south across the area, damaging thunderstorm wind gusts within the
strongest, better organized cell clusters.

Cold and dry air advection reaching the local waters in the wake
of today`s front will likely hoist evening through Friday morning
Wind Advisory flags to account for greater than 20 knot sustained
northerly winds. Convection along and ahead of the front will
quickly transition to the far offshore Gulf waters during the
early evening hours. The backing cool and dry air mass will
finally introduce Autumn to area, albeit a month late! Pristine
weather both Friday and Saturday; clear skies and weakening
veering easterlies as cool mornings in the 40/50s warm into the
70s/low 80s. As early week upper ridging moves east of the state,
lowering western Plains surface pressure will swing winds back
onshore by Sunday, ushering in slightly higher moisture through
the final week of the month. Primarily early week mid-high level
clouds and a subsequent day slightly above normal diurnal temperature
curve; low to mid 60 minimum temperatures that will warm into the
early afternoon mid to upper 80s through Tuesday. A flattened
South Plains ridge/near zonal flow pattern will suppress much in
the way of rain and keep mid to late week conditions partially
cloudy and still unseasonably warm (upper 60/lower 70 mins - near
90 F maxs) under a persistent onshore fetch. Slight rain probabilities
will exist over the maritime with weak lobes of southwestern-based
positive vorticity advection (PVA) passing through and possibly
increasing late period widely scattered -TSRA, a pattern similar
to yesterday`s areal coverage. 31


Prefrontal trof will push off the coast today with light offshore
flow then prevailing thru most of the afternoon. Speeds start
increasing toward evening...and much more substantially shortly after
sunset as the front itself and cooler airmass arrives. Small craft
advisory will be required overnight into parts of Friday w/20-25G30kt
winds and seas building to 7-9 ft offshore. Winds/seas begin settling
down Fri night and gradually veer to the SE late Saturday as high
pressure moves eastward. Onshore flow will then persist well into
next week. 47


Variety of wx across the region this morning ranging from some
shra/tstms near the coast, dense fog west of the metro area to VFR
conditions elsewhere. Think most areas will trend back toward VFR
territory toward mid morning. Exception might be in/around any
convection that develops ahead of prefrontal trof & cold front that`ll
be moving thru SE Tx during the day. With the exception of the coast,
winds will shift to the north in the morning but an increase in speeds
will lag until the actual front crosses the area later in the day.
Clear skies are expected tonight with strong NNE winds near KGLS.  47


College Station (CLL)      80  52  79  51  79 /  50   0   0   0   0
Houston (IAH)              85  55  78  52  80 /  40  10   0   0   0
Galveston (GLS)            84  66  77  64  77 /  50  10   0   0   0




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