Active weather will quickly unfold over the next several hours with multiple hazards

• Severe weather…including all modes (damaging winds, large hail, and tornadoes) will be possible
• Heavy rainfall and street flooding will be possible.
• Timing: 900am-500pm
• Highest tornado and severe threat will be along and south of I-10…an isolated strong tornado is possible.
• Powerful onshore winds of 35-45mph areawide will result in minor coastal flooding this afternoon
• Wind advisory in effect for the entire area
• Gale warning for all waters

Actions:  

• Have multiple ways to receive warnings today (enable cell phone emergency alerts)
• Have a plan to react should a warning be issued for your area

For severe weather/tornado warnings:

• Seek shelter in a sturdy well built structure on the lowest floor away from windows (interior closet or bathroom)
• In office buildings/schools: shelter in an interior hallway away from windows or interior stairway. Do NOT shelter in areas with high vaulted ceilings (gyms), warehouses, ect.
• Storms will be moving extremely fast, warning lead times will be short…act immediately if a warning is issued for your area.

Overview:
Highly impressive upper level storm system now over west Texas will bring numerous weather threats to Texas today. Strong lift is inducing pressure falls this morning over SC TX where a potent surface low will form and move ENE/NE across SE TX this afternoon. High resolution guidance shows “incredible” surface pressure falls on the order of 20mb in 6 hrs over our region today which will result in a very significant low level mass influx of deep moisture into the region. Current dewpoints are 58 at Palacios and 68 at Brownsville versus 39 at Livingston. As surface pressures tank, low level jet will quickly develop and transport mid and possibly upper 60 degree dewpoints from S TX to near the I-10 corridor this morning. Warm front looks to move through the coastal counties and at least into southern Wharton, Fort Bend and Harris with all areas along and south of this boundary likely primed for a robust severe weather potential.

Severe:
High resolution models continue to be aggressive with surface based instability developing over the southern portions of the area today and when combined with the “off the charts” shear in place, all severe weather modes are a concern. We shall see if the instability will be as great as the Hires data suggest, if so a fairly significant outbreak of severe weather including damaging tornadoes will be possible. Main focus of the severe threat will be along and south of I-10 including the metro Houston area. Supercell structures may evolve over the building warm sector late morning with an increasing tornado threat as low level winds remain backed out of the E/ESE and quickly veer to SW in the mid levels producing significant low level shear. Squall line quickly approaches from the west and sweeps across the region this afternoon…damaging winds will be likely with this line as 700mb jet punches in from the west.

SPC has nudged the 3 out of 5 risk area slightly northward overnight and this seems reasonable given the hires guidance showing upper 60 degree dewpoints reach into southern Harris by early afternoon.

Heavy Rain:
Radar is already showing an increase in showers and thunderstorms and this trend will continue into the day. Potential for cell training ahead of the main line yields a heavy rainfall risk near/along the warm front today. No adjustments have been made to the rainfall totals with widespread 1-3 inches likely and isolated amounts of 4-5 inches. Given nearly saturated air column by midday, hourly rainfall rates of 1-2 inches per hour will be possible. Street flooding continues to be the main threat.

Wind:
Impressive wind profiles will come to bear over the region for much of the day with surface winds quickly responding to the steep pressure falls. Sustained winds of 25-35mph with gusts of 40-45mph will be common over much of the area for much of the day. Power outages will be possible. Very strong winds just above the surface will be transported to the ground in showers and thunderstorms and gusts of 50-60mph will be possible.

Coastal/Marine:
Dangerous marine conditions are developing. Southerly winds will increase rapidly this morning into the 30-40kt range with gusts of 50kts. Seas rapidly build 10-15ft offshore Gulf waters and 6-9 ft inland bays. Strong surface force on the water surface will result in minor coastal flooding of low lying areas this afternoon along the Gulf beaches and in the bays. Winds and seas will be slow to subside tonight behind the cold front. Small craft should be in port and remain in port today.

 

Severe Weather Outlook (Today):

Jeff Lindner
Director Hydrologic Operations Division/Meteorologist
Harris County Flood Control District
9900 Northwest Freeway  |  Houston, Texas  77092
346-286-4000 (main)  |  346-286-4165 (direct)  |  281-924-2091 (cell)
jeff.lindner@hcfcd.org   | Twitter: @jefflindner1

 

Sent by Victoria Clifton, EHCMA, on behalf of:

David W. Wade
Industrial Liaison
Harris County Office of Homeland Security & Emergency Management
713-881-3100 Office
713-545-9299 Mobile
David.wade@oem.hctx.net
www.readyharris.org