Alert archive / Texas / Flash Flood Warnings in 2017

Flash Flood Warning 2, NWS Houston/Galveston, TX

January 20, 20174 counties in Texas

NWS Houston/Galveston, TX issued this flash flood warning at Jan 20, 2017, 6:25 PM CST for 4 counties in Texas. It was in force for 2 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jan 20, 2017, 6:25 PM CST (00:25 UTC)
Expired: Jan 20, 2017, 8:30 PM CST
In force: 2 hr
Issued by: NWS Houston/Galveston, TX
Area: Storm-based polygon
Flood severity: None

Counties Brazoria County, TX, Chambers County, TX, Galveston County, TX, Harris County, TX

The radar

The Houston radar (KHGX), 17 km from the middle of the area, began a volume at 00:24 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 0.4 hours before the alert went out and 191 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 627 J/kg
Mixed-layer CIN: -37 J/kg
Mixed-layer LCL: 842 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 68 m²/s²
0-3 km storm-relative helicity: 156 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 0.9

Open this sounding in Storm Lab

The text

As transmitted.

223 
WGUS54 KHGX 210025
FFWHGX
TXC039-071-167-201-210230-
/O.NEW.KHGX.FF.W.0002.170121T0025Z-170121T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Houston/Galveston TX
625 PM CST FRI JAN 20 2017

The National Weather Service in League City has issued a

* Flash Flood Warning for...
  Harris County in southeastern Texas...
  Northwestern Galveston County in southeastern Texas...
  West central Chambers County in southeastern Texas...
  North central Brazoria County in southeastern Texas...

* Until 830 PM CST.

* At 623 PM CST, Doppler radar and automated rain gauges indicated
  thunderstorms producing heavy rain across the warned area. Up to
  one inch of rain has already fallen in less than thirty minutes in
  parts of the warned area and additional rainfall is expected. Rain
  rates in excess of two inches an hour is possible with this
  activity. Flash flooding is expected to begin shortly.

* Some locations that will experience flooding include...
  Pasadena, Pearland, League City, Baytown, Friendswood, La Porte,
  Deer Park, South Houston, Seabrook, Galena Park, Jacinto City,
  Webster, Beach City, Kemah, Clear Lake, Greater Fifth Ward, Fourth
  Ward, Second Ward, Greater Eastwood and Greater Hobby Area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.

A Flash Flood Warning means that flooding is imminent or occurring.
If you are in the warned area move to higher ground immediately.
Residents living along streams and creeks should take immediate
precautions to protect life and property.

&&

LAT...LON 2951 9486 2948 9523 2957 9538 2982 9539
      2983 9487

$$

Huffman

1 follow-up statement

254 
WGUS74 KHGX 210137
FFSHGX

Flash Flood Statement
National Weather Service Houston/Galveston TX
737 PM CST FRI JAN 20 2017

TXC039-071-167-201-210230-
/O.CON.KHGX.FF.W.0002.000000T0000Z-170121T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Harris TX-Galveston TX-Chambers TX-Brazoria TX-
737 PM CST FRI JAN 20 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 830 PM CST FOR
HARRIS...NORTHWESTERN GALVESTON...WEST CENTRAL CHAMBERS AND NORTH
CENTRAL BRAZORIA COUNTIES...

At 733 PM CST, automated rain gauges indicated that heavy rain had
fallen over the area. Up to four inches of rain has already fallen.
Flash flooding is already occurring. Thunderstorms are continuing to
exit the warning area and additional flash flooding is not expected,
but high water is being reported in many locations via Houston
TranStar including Interstate 10 at Jensen and Interstate 45 at
North Main. Residents are urged to check road conditions before
departing as low-lying areas and underpasses will take longer for
water to drain.

Some locations that will experience flooding include...
Pasadena, Pearland, League City, Baytown, Friendswood, La Porte, Deer
Park, South Houston, Seabrook, Galena Park, Jacinto City, Webster,
Beach City, Kemah, Clear Lake, Greater Fifth Ward, Fourth Ward,
Second Ward, Greater Eastwood and Greater Hobby Area.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.

A Flash Flood Warning means that flooding is imminent or occurring.
If you are in the warned area move to higher ground immediately.
Residents living along streams and creeks should take immediate
precautions to protect life and property.

&&

LAT...LON 2951 9486 2948 9523 2957 9538 2982 9539
      2983 9487

$$

Huffman

The office that day

Everything else NWS Houston/Galveston, TX issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 20, 6:06 PM CST	Special Marine Warning	HGX		84 min
Jan 20, 6:08 PM CST	Special Weather Statement	HGX	Harris	37 min
Jan 20, 6:17 PM CST	Areal Flood Advisory	HGX	Brazoria, Chambers, Galveston, Harris, Liberty	3 hr
Jan 20, 6:24 PM CST	Special Weather Statement	HGX	Chambers	66 min
Jan 20, 7:24 PM CST	Special Weather Statement	HGX	Chambers	51 min
Jan 20, 9:24 PM CST	Areal Flood Advisory	HGX	Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty	111 min
Jan 20, 9:44 PM CST	Special Weather Statement	HGX	Liberty	46 min
Jan 20, 10:02 PM CST	Special Weather Statement	HGX	Montgomery, San Jacinto	58 min
Jan 20, 10:59 PM CST	Special Weather Statement	HGX	San Jacinto	76 min
Jan 20, 11:01 PM CST	Special Weather Statement	HGX	Harris, Liberty, San Jacinto	74 min
Jan 20, 11:03 PM CST	Special Weather Statement	HGX	Chambers	72 min
Jan 20, 11:12 PM CST	Areal Flood Advisory	HGX	Harris, Liberty, Montgomery	3 hr
Jan 20, 11:15 PM CST	Areal Flood Advisory	HGX	Liberty, Montgomery, Polk, San Jacinto, Walker	3 hr
Jan 20, 11:32 PM CST	Special Weather Statement	HGX	Polk	28 min
Jan 20, 11:41 PM CST	Areal Flood Advisory	HGX	Chambers, Fort Bend, Harris, Liberty	2 hr
Jan 21, 12:32 AM CST	Special Weather Statement	HGX	Liberty	13 min
Jan 21, 3:52 AM CST	Gale Warning	HGX		42 hr
Jan 21, 6:05 AM CST	Dense Fog Advisory	HGX	Austin, Brazoria, Brazos, Burleson, Colorado, Fort Bend and 12 more	4 hr
Jan 21, 6:23 AM CST	Marine Dense Fog Advisory	HGX		4 hr
Jan 21, 1:10 PM CST	River Flood Warning	HGX	Brazoria	66 hr
Jan 21, 3:29 PM CST	Wind Advisory	HGX	Austin, Brazoria, Brazos, Burleson, Chambers, Colorado and 17 more	26 hr
Jan 21, 3:41 PM CST	Low Water Advisory	HGX		29 hr

Nearby

Flash Flood Warnings in Texas, 2017 Every flash flood warning in 2017

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.