Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Houston/Galveston Texas
613 am CST Monday Feb 8 2016
VFR conditions to prevail for next 24 hours. A cold front moved
across the area early this morning. Skies behind the front should
be mostly sunny with some scattered high clouds. Winds will be
from the north at 15 to 25 knots for much of the day today...
decreasing to 5 to 10 knots overnight tonight.
According to the khgx VAD wind profile winds at 020 are from the
north at 35 to 40 knots. 44
Previous discussion... /issued 423 am CST Monday Feb 8 2016/
.High fire danger today...
at 10z...surface analysis shows high pressure over the Texas Panhandle
pushing into Texas with a cold front moving through southeast Texas. Winds
have shifted to the northwest across the area and should increase later
this morning as the pressure gradient increases. Surface dewpoints
were already in the teens to low 20s across North Texas and north central Texas.
This airmass should move into southeast Texas later today. Latest water
vapor imagery and 500mb analysis show upper level pattern
consistent with model guidances from the last couple of days.
Namely a deep trough has formed over the Great Lakes with a trough
axis rotating through Texas. Broad upper level ridge has formed
over the Pacific coast with strong north/northwest flow aloft through the
plains and Texas.
In what should be a rather quiet weather week...the main concern
will be impacts from critical fire weather conditions for today.
As mentioned before there is already a dry airmass advecting into
the area from North Texas. Dewpoints in the low 20s could end up being
closer to 10f with deep mixing in the boundary layer. Forecast
soundings show a mixed layer up from the surface to 850mb. Both
the NAM/GFS show more than 40 knots of wind at 850mb which could
mix down in the form of wind gusts. Wind at 925mb is a little less
but still supportive of sustained winds near 20 miles per hour during the
early afternoon with gusts near 30 miles per hour. A Wind Advisory for the
area looks reasonable given these conditions.
Maximum temperatures today are forecast to reach the upper 50s to low 60s.
The challenge with the temperature forecast will be how much cold
advection really occurs. Temperatures at 850mb drop from 3c-5c down to 0c
to -2c by late afternoon. The challenge will be if cold advection
is enough to offset day time heating and mixing. As such should
low dewpoints be achieved with slightly higher maximum temperatures than
forecast...relative humidity levels could drop below 15 percent
for the afternoon. Right now 14 to 20 percent relative humidity is
forecast. This combined with the gusty winds expected and
cured/dry vegetation support the potential for rapid fire growth
and a high fire danger. For this reason a red flag warning has
been issued for today. This is the first red flag warning issued
since January 21 2014.
Overall there is not a lot of change in the forecast pattern for
the week. Upper level trough remains over the eastern third of the
U.S. While ridging over the Pacific coast becomes a bit more
progressive and moves east into The Rockies by the weekend. Cold
airmass the next couple of days should modify Wednesday/Thu/Fri as
925-850mb flow becomes west/SW allowing boundary layer temperatures to
increase. Warming is not as dramatic as in previous forecasts but
still noticable jump in maximum temperatures into the 70s. Next cold front
looks to push through Friday night into Saturday which will knock
temperatures down a few degrees for the weekend. That said both GFS/European model (ecmwf)
ensemble MOS numbers show quite a bit of variance and 5 degree
Standard deviations so fairly low confidence in temperature
forecast for the extended.
Marine... a dry cold front moved off the coast this morning with
north winds expected to quickly strengthen to advisory levels
between 4 and 6 am. Advisory conditions will remain over the Bay and
Gulf waters through this afternoon. However...winds will gradually
weaken to caution levels over the bays. High pressure expanding over
the waters from south Texas will loosen the surface pressure
gradiant and back offshore winds around to the west and northwest
from late Wednesday into Thursday. A large ridge of high pressure
over the Great Lakes region will ensure that a light onshore flow
and 2 to 4 foot seas heights continue into the weekend. 44
a very dry air mass behind this mornings cold front will generate
elevated fire weather conditions. Average afternoon relative humidity values to
fall to the middle-teens over the entire (non-coastal) forecast area.
Northwest winds will be between 15 to 20 miles per hour with frequent gusts
to 25 miles per hour. Given the well cured fuels across the region this will
be the first time we have had these ingredients of available
fuel/strong winds/low relative humidity come together in nearly two years. A red
flag warning is in effect from this morning through 7 PM tonight.
Preliminary point temps/pops...
College Station (cll) 58 34 61 40 68 / 0 0 0 0 0
Houston (iah) 60 36 61 41 68 / 0 0 0 0 0
Galveston (gls) 60 42 58 48 63 / 0 0 0 0 0
Texas... Wind Advisory until 6 PM CST this evening for the following
GM...Small Craft Advisory until 6 PM CST this evening for the
following zones: Galveston Bay...Matagorda Bay.
Small craft should exercise caution from 6 PM CST this evening
through this evening for the following zones: Galveston
Small Craft Advisory until midnight CST tonight 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.