Areal Flood Warning 14, NWS Houston/Galveston, TX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
326 PM CDT Wed May 19 2021

.SHORT TERM [Through Thursday Night]...

Though there's a few embedded lightning strikes associated w/ the
MCV off the coast of Matagorda, the bulk of precipitation across the
region has remained stratiform in nature today. This is complements
of a more worked over/stabilized airmass left in the wake of last
nights storms along with the convection that pushed off the
mid/lower coast this morning. Rainfall rates have been cooperative
for the most part - mostly remaining <1/4/hr. That said there is
still some ongoing road flooding over parts of Jackson & Matagorda
Counties who have seen the most significant precipitation over the
past couple days and where the ground can no longer absorb anything.

Band of light to occasional precip should continue edging eastward
overnight with the "heaviest" precip along the coast and offshore.
MCV should move northward across western parts of the area and
become re-absorbed in the mid level trof.

In coordination with surrounding offices, felt it may be best to
keep the FF Watch as is for the time being...at least until its
clear that things remain non-convective and rain rates behave
themselves. There is some ongoing river/stream flooding and grounds
are fairly saturated. It wouldn't take all that much for runoff to
pose problems esp the southern tier of counties in the CWA. That
said, think the overall threat for significant issues is becoming
more localized versus widespread. We'll let the evening and night
crew keep an eye on trends. They may be able to reconfigure and/or
cancel parts of the Watch.

For Thurs, moisture axis should be further east than it was today
and PW's will be lower. Think we'll see some sct shra/tstms to begin
developing during the late morning and afternoon hours as convect
temps are approached. Locations along and east of I-45 should see
the better chances/coverage. As East Coast ridging slowly expands
westward, look for the moisture axis to do the same Thurs night and
into Friday. More on that below.  47

&&

.LONG TERM [Friday Through Wednesday]...

Due to the ever-persisting onshore flow, moisture will continue to
linger over the area into the weekend. An axis of 2+" PW values will
slowly move in from the east throughout the day on Saturday and into
Saturday night. There is model consensus on a shortwave wrapping
around the western flank of a mid-level high which will provide
enough PVA to lift the moisture in place. So, the end result is PoPs
prevailing for the CWA through Saturday night. As a result of the
2+" PW values, locally heavy rainfall will be possible on Saturday.
Fortunately, this will be more isolated and not widespread like
we've seen over the past few days. There will be a gradual shift to
both decreased PoPs after Friday (minus Saturday afternoon) and a
westward shift of PoPs going into Saturday night as the moisture
axis continues to move westward. Going into Sunday, some of our
northeastern and eastern counties will have less than a 20% of rain
which is a much welcome change for these locations. The rest of the
CWA follows suit going into Sunday night as rain chances drop to
less than 10% across the region. Let's briefly backtrack and discuss
what the lingering moisture will do for our temperatures going into
the weekend. Cloud cover will remain mostly intact through Sunday
morning, so afternoon highs on Friday and Saturday will be about 5
degrees or so below normal. Anticipating highs in the upper 70s/low
80s. Overnight temperatures will not cool off that much either due
to the lack of radiational cooling with the persistent cloud cover.
The result is above normal temperatures for Friday and Saturday
night with lows in the upper 60s/low 70s. On Sunday, cloud cover
begins to erode from east to west as slightly drier air moves in.
Not necessarily expecting an emergence of clear skies, but more than
likely partly cloudy skies since onshore flow will continue to
prevail.

Since peaks of sunshine will finally be able to make its way to the
surface on Sunday, this will mark the start of a warming trend. Over
the weekend, a mid/upper-level ridge will build in over the Southern
Plains and southeastern U.S. Temperatures going into next week look
rather warm with highs in the mid 80s by Monday and upper 80s by
Wednesday. There is a bit of caveat to this though. A few shortwaves
will be embedded in the flow of the mid-level ridge. With PW values
remaining above 1.6" and afternoon CAPE values ranging from 1500-
2500 J/kg, thunderstorm development in the afternoon hours are
possible. It is a bit far out to place significant weight in the
timing of these shortwaves, so PoPs in the afternoon hours on Monday-
Wednesday are in the realm of 20-30%. Looking a bit beyond the
forecast period, extended guidance does indicate a continuation of
the upward temperature trend. June does begin in less than two
weeks...just throwing that out there.

Batiste

&&

.MARINE...

Will maintain the ongoing marine advisories with the unsettled wx
(Small Craft Advisory, Coastal Flood Advisory, Rip Current
Statement. Seas are running 6-8 ft, water levels 1-2ft above normal,
elevated surf and rip current risk. Winds may be variable and gusty
at times tonight with the precip offshore. they'll eventually return
to an onshore direction with moderate speeds/seas for the next
several days. PETSS guidance is advertising water levels peaking
around 3.5ft MLLW the next several days around times of high tide.
Could see some minor coastal flooding around those times at the
lower lying, more vulnerable locations.  47

&&

.HYDROLOGY...

Several rivers are above, or are forecast to be, flood stage. Please
see water.weather.gov/ahps2/index.php?wfo=HGX for more info. For the
Houston bayou information, see harriscountyfws.org . 47

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL)  66  81  70  80  70 /  60  30  30  60  30
Houston (IAH)          69  81  70  80  71 /  70  50  60  70  40
Galveston (GLS)        71  80  73  80  74 /  90  60  60  60  50

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...Flash Flood Watch through Thursday afternoon for the following
     zones: Austin...Bolivar Peninsula...Brazoria
     Islands...Brazos...Burleson...Chambers...Coastal
     Brazoria...Coastal Galveston...Coastal Harris...Coastal
     Jackson...Coastal Matagorda...Colorado...Fort
     Bend...Galveston Island...Grimes...Houston...Inland
     Brazoria...Inland Galveston...Inland Harris...Inland
     Jackson...Inland Matagorda...Madison...Matagorda
     Islands...Montgomery...Northern Liberty...Polk...San
     Jacinto...Southern
     Liberty...Trinity...Walker...Waller...Washington...Wharton.

     Coastal Flood Advisory until 7 PM CDT this evening for the
     following zones: Bolivar Peninsula...Coastal
     Galveston...Coastal Harris...Galveston Island.

     High Rip Current Risk through late Thursday night for the
     following zones: Bolivar Peninsula...Brazoria
     Islands...Galveston Island...Matagorda Islands.

GM...Small Craft Advisory until 7 AM CDT Thursday 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...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.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
148 PM CDT WED MAY 19 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1228 AM     FLASH FLOOD      5 NE JERSEY VILLAGE     29.94N 95.52W
05/19/2021                   HARRIS             TX   LAW ENFORCEMENT

            HARRIS COUNTY SHERRIFF OFFICE REPORTS
            FLOODED ROADWAY AT WEST SAM HOUSTON PARKWAY
            ONRAMP BY TOMBALL PARKWAY AT APPROXIMATELY
            12:28 AM CDT.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
155 PM CDT WED MAY 19 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1228 AM     FLASH FLOOD      4 E ALDINE              29.90N 95.31W
05/19/2021                   HARRIS             TX   LAW ENFORCEMENT

            HARRIS COUNTY SHERRIFF OFFICE REPORTS
            FLOODED ROADWAY AT INTERSECTION OF EASTEX
            FREEWAY AND ALDINE MAIL ROUTE ROAD AT
            APPROXIMATELY 12:28 AM CDT IN NORTHEAST
            HOUSTON.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
356 PM CDT WED MAY 19 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1100 PM     TSTM WND DMG     1 ENE WEST UNIVERSITY P 29.72N 95.42W
05/18/2021                   HARRIS             TX   COUNTY OFFICIAL

            CITY OF HOUSTON EMERGENCY MANAGEMENT REPORTS
            SEVERAL TREES DOWN ACROSS THE RIVER OAKS AND
            MONTROSE AREAS OF HOUSTON.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
401 PM CDT WED MAY 19 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1100 PM     TSTM WND DMG     2 N WEST UNIVERSITY PLA 29.74N 95.43W
05/18/2021                   HARRIS             TX   COUNTY OFFICIAL

            CITY OF HOUSTON EMERGENCY MANAGEMENT REPORTS
            SEVERAL TREES DOWN ACROSS THE HEIGHTS REGION
            OF NORTHWEST HOUSTON.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
437 PM CDT WED MAY 19 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1115 PM     TSTM WND DMG     6 NW JACINTO CITY       29.83N 95.30W
05/18/2021                   HARRIS             TX   PUBLIC

            CITY OF HOUSTON EMERGENCY MANAGEMENT REPORTS
            SEVERAL TREES DOWN ACROSS NORTHEAST HOUSTON
            STRETCHING FROM TRINITY AND HOUSTON GARDENS
            TO MOUNT HOUSTON TO GREENWOOD PARK.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
439 PM CDT WED MAY 19 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1050 PM     TSTM WND DMG     1 NW TOWN WEST          29.67N 95.64W
05/18/2021                   FORT BEND          TX   COUNTY OFFICIAL

            CITY OF HOUSTON EMERGENCY MANAGEMENT REPORTS
            SEVERAL TREES DOWN ACROSS THE MISSION BEND
            REGION OF SOUTHWEST HOUSTON.

&&