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Area Forecast Discussion (AFD)

Issued by Houston/Galveston, TX (HGX)

                            
000
FXUS64 KHGX 171741
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1241 PM CDT Tue Sep 17 2019

.AVIATION...
A mixture of ceilings across the terminals this afternoon ranging
from LIFR to VFR ceilings, with those lower ceilings stretched
across IAH and southward. Visibilities have also lowered to 
MVFR/IFR criteria at TAF sites experiencing showers this 
afternoon. These showers and very isolated thunderstorms are 
associated with now Tropical Depression 11, which should continue 
to push onshore later this afternoon. The main impact associated 
with this system remains the threat for heavy rainfall. Terminals
along the coast and as far north as IAH can expect heavy downpours
reducing visibilities periodically through out the TAF period. 
Short term guidance is hinting at a lull in development during the
early evening hours before ramping back up later this evening 
along the coast and spreading further inland during the early 
morning hours. Winds will become gusty, especially along the 
coast, associated with these bands of showers. Ceilings and 
visibilities will again be reduced similar to last night, lowering
to LIFR to MVFR criteria.

Hathaway

&&

.PREV DISCUSSION... /ISSUED 952 AM CDT Tue Sep 17 2019/ 

UPDATE...

..FLASH FLOOD WATCH IN EFFECT FROM 1 PM CDT THIS AFTERNOON
THROUGH WEDNESDAY AFTERNOON...

Showers and isolated thunderstorms are continuing to fill in
across the coastal counties and Gulf waters this morning,
associated with an upper level disturbance moving very slowly to
the northwest across the northwestern corner of the Gulf of
Mexico. The southern portion of Harris County and northern extent
of Galveston County have already seen 1.5 to nearly 3 inches of
rain over the past 12 hours. We have also seen observed rain 
rates close to 1.5 inches per hour associated with stronger 
storms. Heavy rainfall remains possible through the remainder of 
the day, with the best chance south of a line from Columbus to 
Conroe to Liberty. Precipitable water values are expected to 
increase late this afternoon and through the overnight period as 
the upper level low continues to advect in deep tropical moisture.
The track of this disturbance is going to be critical in both the
placement and amount of rainfall. Keep up with the forecast as 
minor details are continuing to evolve with the latest model 
guidance.

We are continuing to message the following flood safety tips:
- "Turn Around, Don't Drown." Isolated underpasses or low-water
 crossings may be life threatening
- Monitor the NWS, your local media, HCFCD and other official
  weather information sources.

Hathaway

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      73  89  73  86  73 /  60  70  60  80  70 
Houston (IAH)              76  85  75  84  76 /  80  90  80  90  50 
Galveston (GLS)            78  84  80  87  81 /  90  90  80  80  50 

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Tropical Storm Warning for the following zones: Brazoria 
     Islands...Coastal Brazoria...Coastal Galveston...Coastal 
     Harris...Galveston Island and Bolivar Peninsula. 

     Flash Flood Watch through Wednesday afternoon for the following 
     zones: Brazoria Islands...Chambers...Coastal Brazoria...
     Coastal Galveston...Coastal Harris...Coastal Matagorda...
     Fort Bend...Galveston Island and Bolivar Peninsula...Inland 
     Brazoria...Inland Galveston...Inland Harris...Inland 
     Matagorda...Matagorda Islands...Northern Liberty...Southern 
     Liberty...Wharton.

GM...Tropical Storm Warning 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...
     Galveston Bay...Waters from High Island to Freeport TX from 
     20 to 60 NM. 

     SMALL CRAFT SHOULD EXERCISE CAUTION until 7 PM CDT this evening 
     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...Galveston Bay...
     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.

&&

$$

Aviation/Marine...08