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Area forecast discussion 
National Weather Service Houston/Galveston Texas
453 am CST Tuesday Mar 3 2015

dense morning fog that will limit visibilities to under a 1/2 mile
will persist a few hours after sunrise...lingering pockets of fog
through as late as noon. Sea fog will pull just offshore with areas
of fog affecting the local bays and Gulf waters through Wednesday.
A weak warm front will work its way across the forecast area
through the day...southeasterlies will increase dew points into
the middle 60s in the warm front's wake. Low rain chances for
either light drizzle/mist or -shra with possible brief breaks in
the lifting fog/cloud deck by early afternoon. Within this warm
air advection pattern of strengthened moist onshore flow...welcome
hints of sun will aid in warming interior locales into the lower
to middle 70s. A large upper low rotating off the Southern
California coastline will begin advancing east as a open wave
trough into Baja California/northwest Mexico through early Wednesday. This will be
the main impetus to heightened Wednesday precipitation chances.

This upper low's associated surface trough/cold front will take
shape over north central Texas by this time tomorrow morning. An
Arctic air mass spilling out of the central Canadian provinces...
along with a substantial push from a near 1040 mb northern U.S
plains high...will push an aggressive cold frontal boundary
across the County Warning Area during the Wednesday evening into Thursday morning
hours. Timing has the main front reaching our northwestern counties
around sunset...through the city during the the coast
around midnight. Wind advisories will likely be needed for the
southern third of the forecast area Thursday morning...with maritime
small craft advisories likely and gale warnings across the Gulf a
possibility. Areawide likely probability of precipitation for mainly rain showers with
isolated thunder on either side of the boundary from Wednesday
morning through Thursday morning. Precipitable waters of great 1.4 inches...near
800-900 convective available potential energy and the region falling in the rrq region of the 25h
jet late Wednesday signal to thunder either just ahead of the
front or forming due to what appears to be strong lift within the
frontal zone itself. The chance for a rain/sleet mix across the
northern third of the forecast area from midnight Thursday through
late Thursday morning is modest of now...the recent
(warmer) forecast soundings are indicative of rain. Drier middle-levels
could wet-bulb enough to produce sleet mixed with rain. The ground
and surrounding structures will likely be too warm to support a
freezing rain threat. Confidence is low as to the timing of
precipitation in tandem with the coldest Thursday am air as there
could easily be a lag and only -shra/isolated thunder would be the end
result. Impacts appear low from any mixed winter precipitation
event. Temperatures will become frigid once again... Friday morning
freeze could reach the coastal communities (mid to upper 20s over
the north-central cwa). Cold air advection will be significant with
a near 30 degree difference between Wednesday afternoon's 70s and
thursday's daytime upper 30s to lower 40s.

The GFS and European model (ecmwf) diverge this weekend...with the more wet European model (ecmwf)
holding back a northern Mexico low and allowing a series of vorticity
maximums to travel across the region Sunday and Monday. The drier GFS
is delayed in this scenario and passes a deeper trough on through
at middle week...majority of quantitative precipitation forecast remains offshore in this solution.
Since both models have performed well of late...have no reason to
jump on any one solution. Thus...have split the difference on
late period precipitation and kept weekend and early week probability of precipitation in
the 30-35 percent category for primarily rain showers. Subsequent
warming from a cold Post-frontal late week...back into the 60s by
Sunday. Mornings will remain chilled through the weekend...but in
the relatively warmer 40s compared to Thursday and Friday morning's
20s and 30s. 31


periods of dense sea fog will persist through Wednesday as warm
moist air continues to override the cooler shelf waters. Fog
should lift with the passage of a strong cold front late Wednesday
evening. Strong north winds in the wake of the front will produce
elevated winds and seas and a gale watch has been issued. Will
also need to keep an eye on potential for low water levels in the
wake of the front as water get pushed out of the bays. Would typically
like to see more of a northwest component in the wind for significant lower
levels to occur (versus north which is fcst)...but strong speeds
are concerning. 47


not planning to make many changes to the 12z tafs from current
ones in effect. Poor flying conditions (lifr/ifr) will persist
this morning with just temporary improvements during the middle to
late afternoon hours. Ceilings and visbys crater again during the overnight
hours. 47


Preliminary point temps/pops...
College Station (cll) 72 62 69 30 40 / 30 30 80 60 30
Houston (iah) 75 64 73 34 42 / 20 20 60 70 30
Galveston (gls) 71 61 70 38 43 / 20 20 40 70 40


Hgx watches/warnings/advisories...
Texas...dense fog advisory until 10 am CST this morning for the
following zones: Austin...Brazoria...Brazos...Burleson...
Chambers...Colorado...Fort Bend...Galveston...Grimes...
Matagorda...Montgomery...Polk...San Jacinto...Trinity...

GM...dense fog advisory until 10 am CST this morning for the
following zones: Galveston Bay...Matagorda Bay...waters
from Freeport to the Matagorda Ship Channel 20 nm to 60
nm...waters from Freeport to the Matagorda Ship Channel out
20 nm...waters from High Island to Freeport 20 to 60 nm...
waters from High Island to Freeport out 20 nm.

Gale watch from Wednesday evening through Thursday morning for
the following zones: Galveston Bay...Matagorda Bay.

Gale watch from late Wednesday night through Thursday afternoon
for the following zones: waters from Freeport to the
Matagorda Ship Channel 20 nm to 60 nm...waters from
Freeport to the Matagorda Ship Channel out 20 nm...waters
from High Island to Freeport 20 to 60 nm...waters from High
Island to Freeport out 20 nm.




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