Jeff Lindner says we could be in for COLD AND WET. and especially WET NEXT WEEK.
Strong cold front moving into SE TX and will result in the coldest weather since last spring this weekend.
Increasing confidence in significant and potentially prolonged heavy rainfall event next week.
Cold front is crossing SE TX currently and winds will pick up out of the north a few hours past sunrise this morning. Batch of thunderstorms ahead of the boundary is moving southward across south TX after brushing our western counties overnight. Cold air advection will onset by mid-morning, but will be offset some by the sunny skies. Think temperatures will warm into the low to mid 70’s and then begin to fall by late afternoon. Models continue to trend colder and colder with this air mass and this will require some modification to the temperatures for the weekend and this evening.
Other item of marginal concern this afternoon is fire weather. Gusty N winds of 15-25mph and incoming dry air mass with dewpoints falling into the 30’s and RH values into the 20’s suggest a modest fire weather concern. The past few weeks have been very dry and surface fine fuels have dried as noted in the increased KBDI values. Main threat would be quick moving grass fires mainly in the counties southwest of Houston (Fort Bend, Wharton, Jackson, Matagorda, Brazoria, and Colorado). Current data does not suggest Red Flag Warning conditions will be met this afternoon.
Will undercut temperatures by 5 degrees for this evening over yesterday as the temperature fall once the sun sets will likely be a little more rapid. Temperatures at 600pm will be near 70 falling to the upper 50’s by 800pm and the mid 50’s by 1000pm with north winds of 5-10mph.
Will lower morning lows on Saturday into the lower 40’s north of I-10 as guidance has trended colder showing a low of 40 at College Station and 44 at IAH. Weak cold air advection continues on Saturday so temperatures will only top out in the mid to upper 60’s for highs. Even colder on Sunday morning with lows into the upper 30’s around Lake Livingston to near 40 Houston metro and mid 50’s on the coast. Some of the usually cold locations could even dip into the mid 30’s. GFS is showing 33 at Conroe Sunday morning. Do not think any widespread freeze is likely even for our northern counties, but a few locations could have near freezing temperatures and frost especially in low lying areas and river bottoms where the dense cold air will settle during the night.
Major upper air pattern change will result in an extended period of wet weather. A strong upper level trough will drop into the SW US and dig into northern MX early next week which will result in strong return flow and moisture advection off the Gulf of Mexico starting late Sunday. Global models remain inconsistent on their handling of how this trough will evolve and when exactly it progresses across TX. The overnight guidance as trended away from the more progressive solutions being offered yesterday and support a slower and more cut off upper level system which would only serve to prolong what is an already very wet forecast. Will start to lean more toward the slower solution with a stalling cold front reaching into the state on Tuesday and our area Wednesday. As the trough digs into the Baja and northern MX region it will capture then Hurricane Vance off the southwest coast of Mexico and recurve it NNE and NE into the Mexican coast and then bring the remaining moisture across TX. Hurricane track guidance is in fair agreement on this pattern and the latest NHC forecast brings Vance to the Mexican coast late Tuesday evening.
Ahead of the upper trough excessive moisture pouring of the top of Vance and increasing Gulf moisture will saturate the air column. The flow aloft will turn increasingly out of the SW on the downstream side of the upper trough and begin to parallel the frontal boundary resulting in it stalling. Numerous disturbances ejecting out of the trough and Vance will move along the stalling front and produce periods of very heavy training rainfall.
Expect heavy convective rains to begins across N TX on Tuesday and begin to sag southward into central and SE TX Tuesday afternoon and Wednesday. Remains of Vance should arrive over top of the region Wednesday and Thursday helping to prolong the heavy rainfall threat. In fact some of the latest guidance hangs on to heavy rainfall into next weekend. PWS values are forecasted to near or exceed 2.0 inches starting late Tuesday and with slowing convection and high potential for cell training excessive rainfall and flooding is becoming a concern. Big question is exactly what happens to the upper trough to our SW and does it cut off and continue the Pacific “El Nino” enhanced tap of moisture through the end of the week as this will be the ultimate determining factor in the duration of the rainfall and the overall totals.
Widespread rainfall amounts of 1-3 inches appears likely for the event, but I strongly caution that these totals may be significantly under forecasted at the moment, but given the onset is still over 4 days away I would not go much higher than that at this time. For what it is worth this is a historical flood setup in the state of TX and in the past similar setups with a stalling frontal boundary, deep upper trough SW of TX, and the remains of an eastern Pacific hurricane have produced devastating flooding in October 1994, October 1998, October 2002, and October 2006.