Flooding potential in Houston area

[archergirl66]

From Jeff:



An area of showers and thunderstorms containing heavy rainfall is moving into the area from the southwest. Hourly rainfall rates have been in the range of .50 to 1.5 inches.



Grounds across Harris County are saturated from rainfall the past 48 hours and much of what falls will run directly into drainage systems.



Rainfall may increase this afternoon as surface heating is realized. In addition, a disturbance located over C TX will move SE into the area this afternoon. The threat for excessive rainfall will continue through Saturday. Moisture levels remain extremely tropical so hourly rainfall rates will be high.

[jeffl]

Mid/upper level trough remains parked over TX with AM soundings showing a moist profile from the surface through 300mb. PWS remains at or above 2.2 inches over most of TX east of I-35 with mean RH values above 70%.

Moist convection cotninues to fire in a weak divergent upper air pattern from SC TX into E TX. Excessive rainfall this morning over SC TX dropped upwards of 6-8 inches of rain resulting in flash flooding. Grounds continue to saturate from rainfall during the last 5 days and flash flood guidance values are running in the 1-2 inch range for a 6 hour period.

Storm motions will be a little faster today, however the saturated air column and high PWS will result in short duration extreme rainfall amounts. Hourly rainfall rates of 2-3 inches will be possible resulting is quick urban flash flooding. Cell mergers and training could result in storm totals of 3-5 inches in a short period of time over isolated locations.

Flash Flood Watch is in effect through this afternoon for all of SE TX. Additional watches are in effect for central and SC TX also.