Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 172042

Area Forecast Discussion
National Weather Service Houston/Galveston TX
342 PM CDT Wed May 17 2017

Relatively nice weather is expected for the rest of the work week,
though onshore flow and increasing moisture will leave potential for
some isolated showers and maybe a thunderstorm. The weekend and next
week look to be less pleasant as a cold front slowly sags into the
area and may or may not make it out alive - the result is a bit of a
muddled forecast as uncertainty fuzzes out rain chances for much of
the first half of next week. Severe weather does not look very
likely at this time, but some locally heavy rain could be a
potential issue to watch for if certain ingredients do indeed come
together just right.

.Through Friday...
Upper and surface low that fueled yesterday`s severe weather in
Oklahoma is ejecting towards the Western Great Lakes region, while a
strong upper jet pushing across the Pacific Coast will help build
the next upper low right down into its place in the coming days. In
the meantime, a streak in the subtropical jet will sag down over
Southeast Texas before washing out. That diffluence aloft along with
increasing column moisture and moderate instability means there`s
some potential for convection. However, forecast soundings show it
may be difficult to beat the cap, so I keep PoPs light for now. If
the cap ends up being a bit weaker or we get a bit warmer, they may
have to go up - but given the relatively weak deep layer shear,
even then expect any convection would be quick and pulsy.

Winds today have been a bit breezy, and that is expected to continue
at similar levels tomorrow and Friday as the new upper low should
support a new surface low to keep the pressure gradient tight. But
since we`ve been able to allow the wind advisory from last night to
expire, we should (key word - should) be able to escape without
further advisories. For the waters, see the marine section below.

.The weekend and early next week...
As we now have an upper low ejecting northeastward into the Upper
Midwest, the next low should do similarly this weekend. As the
surface low shoots up into Wisconsin, look for the trailing cold
front to drag into our area this weekend. Early on, it should have a
little more vigorous, allowing for higher PoPs Saturday night into
Sunday. From there, however, the front loses steam as its surface
low and upper support get farther and farther away. From here, model
divergence really comes into the picture. The Euro is a bit faster
with a secondary front, which is able to push a boundary through the
entire area by Tuesday morning. As a result, it splatters potential
for rain through the weekend and through the first half of the week.
The GFS is a bit slower with things, and allows for a bit of a dry
period early next week between boundaries. As you might expect, the
GFS ensemble has a wide range of solutions for the first half of
next week, and so a blend seemed the natural way to go to start next
week. As things become more clear in the coming days, expectation is
that we`ll be able to demarcate periods for rain and drier weather a
bit more specifically, but for now there`s too much uncertainty in a
muddled forecast.

What does look a bit more certain is that any front will lack much
of a push of cold, dry air behind it (hence the uncertainty on its
behavior). As a result, only look for humidity to take a mild cut,
and even that may take until the middle of next week to really
become apparent. Temperatures will also fall only a little bit, but
shouldn`t fall much below normal (if at all).



Winds dropped below 15 knots and have remained so but expect after
sunset that winds will edge up a few knots. Seas though have been
slower to come down and have an SCA still in effect for the 20-60nm
waters til 3 am or so. Gradient will support winds bouncing around
between 10-15 and 15-20 knots through Friday night...stronger winds
probably overnight hours. Seas should remain locked into the 3-5
nearshore and 4-7 offshore. A front should finally come off the
coast (assuming the models don`t flip/flop more) ushering in
stronger winds Monday night/Tuesday morning.


College Station (CLL)      82  74  90  74  90 /  20  20  20  10  20
Houston (IAH)              86  75  87  75  88 /  10  20  10  10  20
Galveston (GLS)            82  78  83  79  84 /   0  10  10  10  20


GM...Small Craft Advisory for hazardous seas until 5 AM CDT Thursday
     for the following zones: Waters from Freeport to the
     Matagorda Ship Channel from 20 to 60 NM...Waters from High
     Island to Freeport from 20 to 60 NM.



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