Scientific Forecaster Discussion
fxus64 khgx 111125
Area forecast discussion
National Weather Service Houston/Galveston Texas
525 am CST Wed Dec 11 2019
gradually clearing skies today (mvfr becoming skc) with slowly
weakening north-northeast to NE winds. Lighter NE to east winds tonight. Look
for increasing clouds tomorrow with light NE winds. 42
Previous discussion... /issued 345 am CST Wed Dec 11 2019/
Considerably colder air will reign in the wake of a cold front,
which will give way to gradual warming with fair weather into the
weekend. Rain and thunderstorm chances will increase through
Sunday night into Monday for our next cold frontal passage, to be
followed by cooler weather deeper into next week.
Short term [through thursday]...
Skies remain cloudy across all of southeast Texas early
this morning with temperatures at 3 am ranging from the
low/mid 40s inland to the upper 40s/around 50 at the
coast. Skies will gradually become mostly sunny to sunny
today (the clearing line is currently getting close to
Houston county), and this will likely have an influence
on how high temperatures get this afternoon. If every-
thing GOES as planned (and we clear out), highs should
be able to reach the mid to upper 50s. Mostly clear
skies and light winds support a cold night tonight with
low to mid 30s across our far northern counties, low to
mid 40s central and around 50 at the coast. Clouds
thicken up on Thursday, and if it does not get to
extensive we should see our high temperatures get back
into the 60s. 42
Long term [thursday night through wednesday]...
By Thursday evening, look for a long upper trough axis to be
overhead, though it should eject through the day Friday as
another vort Max/shortwave trough passes through. The Euro is
actually quite explicit with a potent pocket of vorticity, which
spins up a surface low to traverse Texas and bring a cold front
through Friday night, while other guidance is much more muddled.
Ultimately, it's probably not a big deal as far as sensible
weather GOES, other than how much it may tap the brakes on our
warming trend, and may or may not create a more distinct wind
shift. Though even here, winds should be relatively light and
somewhat variable to begin with.
Look for onshore flow to return pretty quickly on Saturday, which
should put things back on track for warming through the weekend.
By Sunday, we'll be looking for highs generally in the 70s. Like
with this most recent front though, as soon as we start to really
push above seasonal averages, it will be time for the next front.
An upper trough will swing through early next week, and as it
crosses Texas, we'll look for development again of a surface low
that will shoot up to the Ohio Valley, trailing our next cold
front behind it.
In addition to that, we'll see moisture pump up from the Gulf at
low levels, and from the Pacific well aloft. This will provide US
with the moisture for our next round of showers and storms.
Neither naefs nor the Euro ensemble show a very anomalous
situation at this range, so I suspect how this plays out will
depend very strongly on frontal timing. 6-7 days out, I have no
real confidence in my ability to suss out such fine details, so
i'll pretty much leave things at that for now.
The northeast winds and elevated seas will slowly diminish
today and tonight. We will still be carrying caution flags
for the bays this morning and advisories off the coast
throughout the day. By tomorrow, all flags/advisories
will probably be lifted. Waters in northern parts of the
bays could get close to low water advisory levels, and we
will continue to monitor. Broad high pressure over the
eastern Seaboard and troffiness across the Yucatan and west
central Gulf will maintain a general northeast to east flow
through Thursday night or Friday. A more prevalent onshore
flow resumes over the weekend and persists until the next
strong cold front pushes off the coast on Monday.
Preliminary point temps/pops...
College Station (cll) 57 36 62 42 70 / 0 0 0 10 0
Houston (iah) 57 41 62 47 69 / 0 0 10 10 0
Galveston (gls) 56 52 62 55 67 / 0 0 10 10 10
GM...small craft should exercise caution until 10 am CST this morning
for the following zones: Galveston Bay...Matagorda Bay.
Small Craft Advisory until noon CST today for the following
zones: coastal waters from Freeport to Matagorda Ship
Channel Texas out 20 nm...coastal waters from High Island to
Freeport Texas out 20 nm.
Small craft should exercise caution from noon CST today through
this evening for the following zones: coastal waters from
Freeport to Matagorda Ship Channel Texas out 20 nm...coastal
waters from High Island to Freeport Texas out 20 nm.
Small Craft Advisory until 9 PM CST this evening for the
following zones: waters from Freeport to Matagorda Ship
Channel Texas from 20 to 60 nm...waters from High Island to