Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 011156
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
556 AM CST Wed Mar 1 2017

.AVIATION...
MVFR/IFR ceilings and/or visibilities will become VFR as the morning
progresses with the passage of a cold front. Southwest to west winds
will shift to the northwest behind the front and become gusty. Overnight,
just some high clouds along with lighter north winds inland but staying
elevated and gusty along the coast.  42
&&

.PREV DISCUSSION... /ISSUED 419 AM CST Wed Mar 1 2017/

DISCUSSION...
A warm start to the day yet again, and if we weren`t going to lose
them all as colder air flooded in behind the front, we might see a
new round of record warm mins. However, the front should work its
way through Southeast Texas this morning, moving through College
Station not long after daybreak, and reaching the coast by
midday or the early afternoon. While some showers and perhaps a
thunderstorm or two is possible along the front, not really
looking for more than a thin line of broken showers/storms.
Behind the front, winds will become gustier as they shift to
northerly. We`ll close out the week with relatively seasonable
and dry weather, but changes are in store. Rain potential will
pick up for the weekend as a coastal trough sets up, and we`ll
look for another frontal passage sometime in the first half of
next week.

Yesterday...
Before getting into the forecast, let`s take a brief look back at
yesterday morning. Thanks to copious amounts of onshore flow, all
four of a main climate sites tied or broke their records for
warmest minimum temperature - not just for the day, but for the
month of February. To give you an idea of how anomalous these warm
nights have been, IAH`s low of 73 yesterday would be a record warm
min for every day until April 11. 73 is the normal low for June
10. And compared to a normal high of 69, yesterday started from a
floor warmer than a "typical" high for February 28. The word
you`re looking for may be "absurd".

Today through Friday...
Radar and observations reveal both a pre-frontal trough and the
cold front approaching Southeast Texas, and the pre-frontal trough
has begun to push through our area. Though that trough did attempt
to spark some showers upstream of our area, things have pretty
much dried up. Left some slight chance PoPs in the far northeast
as there are a few stray echoes up in that direction. Expect most
will miss our area entirely, but some may survive.

Once the front moves through, we may see enough uplift along the
frontal surface to be a bit more successful in producing a few
showers, and perhaps a thunderstorm if it can tap into the cool
temperatures aloft above the cap created by a strong EML. Still,
don`t expect much as most of the CAM guidance can`t manage more
than a thin squeegee line of convection along the front. Expect
most to stay dry, but all have at least a chance to see some rain.
Perhaps more interesting might be the battle of temperatures as
diurnal heating faces off against cold air advection behind the
front. Have jacked up temperatures well inland, and kept stable or
nudged things up near the coast. This is largely due to
temperatures failing to fall up College Station`s way, and think
even a modest bump before cold air surges in gets us up towards
the middle 70s. Expect to push 80 from the Houston metro
coastward as it will be afternoon before cold air really starts to
move in.

Additionally, while winds look to become gustier behind
the front, and could flirt with the wind advisory threshold right
on the coast, will hold tight with only marine headlines for now.
But if we do come in much gustier, the coastal counties may need a
short fuse advisory.

As we go deeper into the afternoon, watch for temperatures to
tank - and by evening, look for us to bust through morning lows.
With the drier weather, expect lows for the next couple of nights
to fall several degrees below normal and feel a bit chilly, but on
the flip side should still be able to warm back to near normal.
On Friday however, winds should finally be veered all the way back
onshore, and we begin the warming trend anew as low level
moisture is restored.

Friday through Monday...
Still much uncertainty about the development of a coastal trough,
and the increase of rain chances in the weekend time frame. If
you believe the Euro (and this forecast tends to lean that way),
look for Saturday night into Sunday to be the prime target for
rain as a coastal trough sets up, and rain slides up the Gulf
Coast underneath a fairly potent shortwave trough moving across
the area. There may even be a hint of a right entrance region
linkup with an upper jet just to help things out a little more.
The GFS, on the other hand, begins this process, but then decides
to (artificially?) pump up a big midlevel ridge ahead of the
trough, rather than the Euro`s idea of a more modest ridge,
allowing the shortwave to scoot through. This keeps any rain
trapped down in South Texas, until things drift upward and help
fuel some showers with a frontal passage Monday evening. Much
prefer the way the Euro is handling the upper pattern, and several
members of the GFS ensemble seem to join in this idea, giving me
further confidence.

Ultimately, the Euro version seems much more realistic, and
leaning heavily to that idea also keeps better continuity with the
previous forecast and with surrounding offices. As far as QPF
goes, there may be some potential for heavy rain, but the Euro
keeps the heaviest rain safely offshore, while most of the area
looks for half an inch or so of rain total over the weekend. That
said, some of those GEFS members also bring up to an inch of rain
to Houston. Of course, the GEFS members are relatively low
resolution, so mostly take that as a signal for more significant
rainfall, as individual cells could drop notably more rain. So,
while it will be good to continue to monitor the forecast in the
coming days for your weekend plans, confidence in the forecast is
generally higher than it was last night.

Middle of next week...
A pretty beefy upper trough in the northern stream will pass
through the Great Lakes Tuesday, and a surface low near Hudson Bay
looks to trail a cold front all the way down to the area. The GFS
keeps upper flow over us relatively zonal, and brings another shot
for rain Tuesday afternoon/evening. The Euro has a fairly similar
idea, but comes in stronger with a midlevel ridge over Texas, and
is noticeably drier, and perhaps even entirely dry. Plenty of time
to work out the details here, so the forecast really only sketches
out the basic idea, and punts on specific details.

Luchs

MARINE...
A cold front will move through the coastal waters late this morning
through this afternoon (ahead of the front early this morning,
look for periods of patchy sea fog, some possibly dense). With
strong north winds and rough seas developing behind the front, will
carry caution flags for the Bays and advisories for the 00-60 nm
waters. At the end of the week and over the weekend, persistent
east to southeast winds could bring above normal tides and some
minor coastal flooding to parts of the area. Look for a lighter
onshore flow for the start of next week. 42

FIRE WEATHER...
Elevated fire weather conditions are expected to develop this
afternoon after the passage of the cold front with relative
humidities falling into the upper 20s to lower 30s, north winds
15 to 20 mph and gusty, and dry grasses across much of the inland
area. Red flag warnings might be needed. Humidities are expected
to fall under 30 both tomorrow and Friday afternoon, but lighter
winds should keep the area out of elevated fire weather conditions.
42

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      74  44  67  42  70 /  10   0   0   0   0
Houston (IAH)              81  48  69  45  70 /  20   0   0   0   0
Galveston (GLS)            76  56  66  54  67 /  30   0   0   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION from this evening through
     Thursday morning for the following zones: Galveston Bay...
     Matagorda Bay.

     Dense Fog Advisory until 10 AM CST this morning for the
     following zones: Coastal waters from High Island to
     Freeport out 20 NM...Galveston Bay.

     Small Craft Advisory from 6 PM this evening to noon CST Thursday
     for the following zones: Coastal waters from Freeport to
     the Matagorda Ship Channel out 20 NM...Coastal waters from
     High Island to Freeport out 20 NM...Waters from Freeport to
     the Matagorda Ship Channel from 20 to 60 NM...Waters from
     High Island to Freeport from 20 to 60 NM.

&&

$$

Discussion...25
Aviation/Marine...42



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