More heavy rainfall and tornadoes are expected late tonight through at least Wednesday for Houston as well as the surrounding areas. This is bad news for these areas because 30″ of rain has fallen in some areas. Currently, Tropical Storm Harvey is situated over Texas but is inching closer to the coast–likely reemerging over the northern Gulf by Monday morning. Harvey has maximum sustained winds of 40 mph at this hour with a slow movement of 2 mph to the SE.
The position of Harvey and slow movement place Houston and much of southern Texas and central Texas in a favorable area for very heavy rainfall for the next few days. As aforementioned, once Harvey moves back over the Gulf of Mexico by Monday morning, it is possible that Harvey will re-intensify into a strong tropical storm (possible maximum sustained winds of 60 to 65 mph). Harvey will then move northeastward, slowly, making landfall just south of Houston by Wednesday morning. This scenario would aid in heavier rainfall rates and an increased tornado threat for much of the mid-Texas coast, upper-Texas coast, southern parts of north Texas, and western Louisiana.
European (Wednesday morning)
3km NAM Rainfall Totals (through Tuesday evening)
A big concern is tonight (Sunday night) for Houston and its suburbs. Short range guidance indicates a feeder band from Harvey may situate itself over this area. These feeder bands can produce rainfall rates of 4-8″ per hour and tornadoes. This will only exacerbate the flooding issues across Houston and do so during the most dangerous time for flooding (at night). The HRRR is indicating 10-24″ may fall over the next 18 hours in the Houston area.
HRRR Future Radar (tonight)
HRRR Rainfall Totals (through 18 hours)
Once Harvey moves inland, again, into Texas on Wednesday, the path becomes uncertain. The uncertain path, and the slow meandering of Harvey over the past few days, is because there is a lack of upper-level features to act as a magnet and steer Harvey out of Texas. The steering currents are too light, and Harvey is ‘stuck’ between a mid-level high to its west and the subtropical ridge across the southeast. This may change by late week into the weekend however, however. An upper-level trough appears to dig into the central plains, which may draw Harvey northeastward. This would place parts of northeastern Texas, southern Arkansas, northern Louisiana, and western Mississippi in a favorable area to see rainfall from the remnants of Harvey. The remnants would produce flooding for these areas. By Saturday, it is possible isolated areas in southeastern Texas may see 50-60″ of rainfall.
European (Friday morning)
WPC Precipitation Forecast (through 7 days)
Firsthand Weather will have updates as needed!