Flash Flood Warning 10, NWS Houston/Galveston, TX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1145 PM CDT Wed Jun 24 2020

.AVIATION...

As the upper low continues to slowly push southward through the area,
current radar imagery shows a line of showers and thunderstorms from
the CXO/IAH area southwestward. Expect coverage to continue to fill
in overnight as ceilings lower back to MVFR and potentially higher-
end IFR levels. Reductions in visibility associated with any developing
showers and storms is once again expected. Light and variable winds
overnight, with gustier southerly winds developing by tomorrow afternoon.
Shower and thunderstorm areas during the day tomorrow are hard to pinpoint
and will probably depend some on what happens across the area overnight.

42/12/05

&&

PREV DISCUSSION... /ISSUED 354 PM CDT Wed Jun 24 2020/

SHORT TERM [Tonight through Thursday]...

The middle to upper level low that is slowly rotating across the
region will keep moderate to high rain chances in place through this
period. While there is enough instability to initiate isolated
thunderstorms, most of the precipitation will be light and in the
form of showers through the early Thursday morning hours. A distinct
deformation zone extending from a weak near stationary coastal
surface boundary up into the middle levels will be the focus needed
to allow for the redevelopment of (overnight) early Thursday morning
convection. Overnight conditions will be warm and humid with
scattered showers forming over the southern two thirds of the
forecast area. Minimum temperatures will be within a degree or two
of lower to middle 70 dew points.

The short range and global model solutions are generally showing a
consolidation of precipitation along or near the coast/points
offshore from after midnight tonight through the sunrise hour. As of
now, prepare for another band to form somewhere near the city
southward and impact more southern communities from before sunrise
through the late morning hours. QPF will range from a few tenths of
an inch to locally 1-2 inches over areas where the banding either
trains of simply slows to a crawl on its southeastern exit. Most of
the action should wane before lunch with scatted shower/isolated
storm activity as this weak coastal synoptic scale boundary lifts
northward as a warm front with the help of daytime heating. Late
morning into early afternoon clearing skies may also allow for the
development of a late afternoon sea breeze that could interact with
old convective outflow or the warm front. With less anticipated
afternoon rainfall and partially clear skies...tomorrow is forecast
to be a few degrees warmer than today; average middle 80s. 31

LONG TERM [Tomorrow Night through Wednesday]...

Elevated rain chances will continue for SE TX through the end of
the week and possibly through most of the upcoming weekend. With
the upper low lingering over the state and a steady influx of 2"
PWs from the Gulf, daytime heating will help with development on
the various boundaries across the CWA on Fri. As the low weakens
further, this general pattern of mainly diurnal activity will be
continuing into Sat/Sun but with slightly less coverage each day.
Upper level ridging will be trying to build over the area by the
start of next week...and this should translate to lower POPs and
higher daytime temperatures. 41

MARINE...

Winds/seas have decreased across the marine waters this afternoon
and should continue this trend tonight as the shower/thunderstorm
coverage decreases tonight. However, we could see more periods of
unsettled weather through the next few days as an upper level low
pressure system lingers over the state. This pattern will also be
helpful in producing periods of more elevated winds/seas and SCEC
flags will likely be needed on occasion. Otherwise, things should
be settling down by the end of the weekend (i.e. these storms) as
high pressure tries to build in over the region. Generally light/
moderate onshore winds to prevail. 41

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      71  85  73  88  73 /  20  30  50  50  10
Houston (IAH)              74  85  77  87  78 /  60  60  40  40  20
Galveston (GLS)            79  83  81  87  82 /  50  60  30  30  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Flash Flood Watch until 6 AM CDT Thursday for the following
     zones: Austin...Colorado...Fort Bend...Inland Harris...
     Waller...Wharton.

GM...NONE.
&&