Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 211119

Area Forecast Discussion
National Weather Service Houston/Galveston TX
619 AM CDT Wed Mar 21 2018

VFR with just some cirrus moving across the area.
Light north to northeast winds early this morning
will become east to southeast at around 5 to 10
knots as the day progresses. Light southeast winds
tonight. Increasing moisture and daytime heating
should bring the area a little more cloud coverage
tomorrow, but VFR conditions should still prevail.

.PREV DISCUSSION... /ISSUED 349 AM CDT Wed Mar 21 2018/


High pressure will become dominant over the area for the mid-week,
before eventually making its way off to the east. A new low will
develop over the Plains and bring in a front that will come to
influence our weather next week, and the focus of the forecast in
the coming days will likely be how significant an impact we will
see, and at what times.

NEAR TERM [Through Today]...

Well, with incipient storms on both the east and west coasts, it`s
probably no surprise that we in Texas are in the process of
becoming ridge city. The radar has only clutter on it, and while
there is some cirrus rounding the ridge axis currently off to our
west, the satellite imagery over the area is not terribly
exciting, either.

But, with clear skies and dry air in place, we`re also in a pretty
ideal setup for radiational cooling tonight. Temperatures across
the area are near or already below typical lows at 3 am, and with
dewpoints in the upper 30s and lower 40s, there`s a little more
room for temperatures to fall some more. Despite the chilly start
to the day, we`ll do just as well warming today with full sun.
High temperatures today are forecast to be right around seasonal

More on this in the fire weather section below, but with continued
low dewpoints, and temperatures a bit warmer, relative humidity
will dip a bit today from yesterday. But, underneath high
pressure, winds will be light.

SHORT TERM [Tonight Through Friday]...

High pressure begins to slowly drift off to the east, and as it
does so, we`ll see onshore winds begin to re-establish tonight.
Winds will still be very light, so don`t expect a surge of
moisture tonight, but it probably should be enough to boost
overnight lows modestly, and accelerate our warmup for the rest of
the week. Both lows and highs will be higher day over day thanks
to the increasing moisture and as the mid-level ridge continues to
move eastward, and by Friday evening looks to be centered over
northeast Mexico. But, at the same time, we`re looking for an
upper trough to push off the Rockies towards the Central Plains -
and with that, lee cyclogenesis will begin at the surface and
develop as it moves into Kansas. This will tighten up the pressure
gradient and strengthen winds, particularly on Friday where we may
see some gusts up to 20 mph well to the west of the Houston metro.

LONG TERM [Friday Night Through Wednesday]...

After a largely quiet week, the weekend will bring us signs of
transition. Moisture continues to increase, with precipitable
water that is progged to increase over an inch Friday afternoon,
and boost up towards 1.5 inches at a max over the weekend. This
max likely won`t be area-wide, but instead in a more narrow
ribbon, but will continue to be above an inch. With well
established southwesterly flow in the 700-850 mb layer, suspect
we`ll be pretty well capped, so while I do start to introduce some
rain chances here, I`d guess the character is more likely to be in
lighter showers that develops underneath the cap. There`s pretty
solid consensus in having instability in place for Sunday as
heights aloft fall, so I do go have some potential for thunder in
the forecast - but think any storms would be rather isolated. What
there is a good deal of confidence in will be increased cloud
cover for the weekend. Still despite that, temperatures should
rise into the 80s.

Now...looking to next week. Last night, I discussed a scenario the
GFS had been stubbornly clinging to, as a cold front comes into
the area and stalls out at the coast underneath a col in a setup
reminiscent of other heavy spring rain setups. Am very happy to
report that the GFS has finally given up the ghost on that idea,
and fallen in line with its ensemble mean and the Euro. This idea
holds the front well to our north in North Texas and the Red River
Valley. Now, as the ridge aloft continues to be squeezed to the
east by an approaching upper trough, we`ll also see vort maxes
come a bit closer. So, we should see our scattered showers and
storms become more numerous into early next week. Eventually, the
upper trough will push through and force the front down our way,
but this is beyond the forecast period at this point.

Of course, just because the model envelope doesn`t really show
our earlier scenario anymore doesn`t mean it`s not going to
happen. Indeed, that it is reminiscent of a spring pattern that`s
occurred before means it`s not entirely off the table. But, that
the major model suites seem to be increasingly having a similar
handle at least helps us keep this scenario in perspective as a
low probability outcome at this time.


North winds early this morning will gradually become east today
and southeast tonight as high pressure moves off to the east.
A persistent onshore flow and building seas will set up for the
remainder of the week and on into the weekend. Caution flags are
likely and advisories might be needed. 42


Elevated fire weather conditions will continue today with
relative humidities bottoming out between 25% and 35%, but
winds will not be as much of a concern. 42


College Station (CLL)      75  50  78  59  80 /   0   0   0   0  10
Houston (IAH)              76  52  78  60  80 /   0   0   0   0  10
Galveston (GLS)            71  63  73  66  75 /   0   0   0   0  10



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