#4799 Postby Tireman4 » Thu Jan 31, 2019 10:04 am
000
FXUS64 KHGX 311140
AFDHGX
Area Forecast Discussion
National Weather Service Houston/Galveston TX
540 AM CST Thu Jan 31 2019
.AVIATION...
Lowering ceilings/visibilities and increasing -RA/-SHRA coverage can
be expected today and tonight. MVFR levels are anticipated, and IFR
levels are possible. Think best TSRA potential will be off the coast.
42
&&
.PREV DISCUSSION... /ISSUED 410 AM CST Thu Jan 31 2019/
DISCUSSION...
After a pleasant, albeit cold, start to the week, we`ll begin a
transition where both descriptors are likely to flip. Temperatures
are expected to become warmer - with low temperature values near
seasonal highs - but also more dreary, with frequent chances of
rain, clouds, and sea fog. This may well continue deep into next
week, until a cold front comes to clear rain chances out and cool
things down on Wednesday or Thursday.
NEAR TERM [Through Today]...
A solid ceiling of 4-6k feet has covered Southeast Texas, and
an overcast sky should be expected to continue through the day.
Despite that, look for a warmer day tomorrow, due in large part to
the fact that temperatures across the area are already near their
daily max from yesterday, and are probably only on their way up as
moderate to strong onshore flow sets up over the Gulf and warm
advection taking place at 850 mb. If there were sun, we could
perhaps make more of a run at warmer temperatures, but we should
look to build to around 60 degrees across the area.
While the radar is relatively empty until you get down to
Brownsville, there is a weak surface low developing down there,
and it should slowly scrape up the lower Texas coast, and rain
showers should accordingly drift up our way as well. As the low
moves up, we should start to see better convergence along the
coast as rain becomes more likely deeper into the day. Further
inland, things are perhaps a little less clear. A shortwave trough
does look to pass across the region today, and the TTU WRF, HRRR
and NAM hint at development of some light showers over much of the
area, while the RAP stays drier. The HREF is also pretty dry,
keeping rain largely confined to the Gulf and much of the
immediate coastal area. Tend to suspect the TTU WRF and HRRR may
be overconvective a bit, so I`ll keep the highest PoPs right on
the coast, but will not go HREF/RAP dry, either.
SHORT TERM [Tonight Through Saturday]...
A bit of uncertain certainty tonight in the behavior of this
coastal low - some guidance brings the low itself out over the
Gulf, while other guidance brings the original low slowly inland
and fills it in, while an MCS sets up over the Gulf and spawns a
mesolow. In the end, it may not make much of a difference, as the
effective result is pretty similar. Rain showers will be most
likely over the water, a bit less so on the coast, and less of a
chance inland, and the low pressure (however it gets there) over
the Gulf moves off to the east, decreasing rain chances by
morning.
Look for another shortwave to roll through Friday, and only a
brief moment of upper ridging Friday night until a more
substantial upper trough rolls through Texas on Saturday. It is
probably little surprise, then, that rain chances never really
leave us through the first half of the weekend. The sustained,
slow warming trend also continues through this period. Again,
clouds and rain will hold things back some, but persistent onshore
flow and low level warm advection should keep on nudging temps up.
LONG TERM [Saturday Night Through Thursday]...
If we have a stretch most likely to dry out...and maybe see a bit
of a break in the cloud cover, it will be Sunday and Monday. An
upper trough will drop off the Rockies and eject northeastward to
the Great Lakes, bringing a deepening surface low along with it.
That low will drop a front down into Texas, but a lingering
midlevel ridge over the Gulf looks to be just strong enough to
hold that front off and wash it out short of our area. We appear
to be on a bit of a razor`s edge with this, but there`s pretty
strong consensus in the guidance that this weak ridging will hold,
so outside of a little bit of a veering in winds up around College
Station...have no impact in our area.
However, by midweek, that ridge`s axis should move off to the
eastern edge of the Gulf, which will provide just enough of a
window for the next front to at least push into the region on
Wednesday. And here is where the guidance begins to diverge
wildly. The GFS slams things on through with a quick frontal
passage on Wednesday and a strong progressive motion of the upper
trough. The Euro, on the other hand, holds the pattern a bit more
stagnant, and doesn`t bring through the upper trough/front combo
until Thursday. This...plays right into these models`
stereotypical bias at medium/long range. Thanks, models, very
helpful of you. FWIW, the Canadian appears to be even slower than
the Euro. For now, given little compelling evidence to sell out
for either a quicker or slower FROPA, will take the forecast of
least regret at this point with a compromise front moving through
Wednesday night. This may well end up working out...at the very
least, this buys us some time to gain clarity on the situation
before shifting the forecast to the end that appears most likely.
MARINE...
Moderate east winds (caution speeds most of the time) and
elevated seas (caution/advisory levels) will persist through
the end of the week. Areas of rain with maybe some embedded
showers or thunderstorms are expected today and tonight.
Lighter southeast to south winds will return to the area
over the weekend. Look for a slight increase in south winds
during the first half of next week. The area`s next cold front
is not expected to push off the coast until Wed/Thu of next week.
A warmer airmass will begin moving over the colder shelf waters
Friday and into next week setting the stage for some sea fog
development. This could end up being a somewhat prolonged fog
event considering the next cold front isn`t expected to push
off the coast until Wed/Thur of next week. There`s still a lot
of details to be worked out in the meantime (timing, sct showers
that could temporarily mix things out, etc). 42
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 59 53 67 56 68 / 40 30 20 30 40
Houston (IAH) 60 54 67 57 68 / 40 40 20 30 40
Galveston (GLS) 59 57 62 58 63 / 70 60 30 30 40
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...Small Craft Advisory from 6 PM this evening to 6 AM CST Friday
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 SHOULD EXERCISE CAUTION through this 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 6 AM CST Friday 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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