Morning update from Jeff: Significant storm system to impact the area today-Halloween. Flooding rainfall and isolated tornadoes are the main threats. Powerful upper level storm system over the SW US this morning is starting to track eastward with strong lift beginning to spread into TX. Deep moisture advection overnight has led to the development of strong thunderstorms from College Station to Katy to Wharton this morning. Luckily these storms are moving quickly northward keeping rainfall manageable. These storms are in response to weak disturbances aloft overtop over increasing Gulf moisture levels. Heavy Rainfall: Moisture will continue to increase today and peak near maximum levels for this time of year on Thursday. In fact if PWS were to reach 2.3 inches this would be close to the maximum level for summertime…so there is no shortage of moisture to work with. Main focus will be on the excessive rainfall threat. Factors are in place to produce excessive rainfall including 1. Slow moving frontal boundary 2. Good upper level divergence 3. Strong moisture advection 4. Cell training 5. Maximum PW values Expect current activity to continue for much of the day and then the main event will enter into the region tonight. Expect a solid line of heavy rainfall to develop along the frontal boundary with high potential for cell training. Where these cells line up will determine where the maximum rainfall will occur. Widespread 2-3 inches is likely with isolated amounts of 5-7 inches. With grounds already wet from previous rainfall, rainfall of this magnitude will produce some significant run-off and rises on area watersheds. Heaviest rainfall axis looks to be shifted closer to the US 59 corridor, but the entire region is at risk. Given run-off is still ongoing from upstream points from Sunday on some of the major rivers this additional heavy rainfall could push some points to action stage or even flood stage. Urban flooding will also be a concern given the potential for 2-3 inch per hour rainfall rates. Severe Weather: No overly concerned with the severe threat. A good amount of low level shear will be in place, but instability is lacking so not expecting widespread severe. This types of setups with a very moist air mass can produced low topped supercells that produce very heavy rainfall and isolated weak tornadoes in their rain cores. Suspect we could see 1 or 2 weak tornadoes wrapped in rain and the warnings will be very short fused. Again I stress that the main impact will be rainfall and potential flooding. Halloween Evening: Good news is that nearly all model guidance clears the rainfall off the coast by 700pm Thursday evening. Could still be dealing with run-off issues and high water, but it is looking likely that the rain will be over by sunset Thursday. North winds of 10-15mph and temperatures in the low to mid 60’s for any evening activities. Weekend: Stronger front clears the area Friday evening with a much drier and cooler air mass ushering in. Lows down into the 40’s by Sunday AM with highs in the 70’s. Starting to look like the break in the rainfall could be brief with moisture wanting to return as early as Sunday afternoon over the frontal boundary. Will likely see rainfall by early next week again as SW flow aloft and increasing Gulf moisture impacts the region.
Posted on: Wed, 30 Oct 2013 13:09:08 +0000
Trending Topics
Recently Viewed Topics
© 2015