Forecast
Discussion:
Good Monday
evening everybody. The highly anticipated rainfall event this past weekend, for
the most part, went relatively well across south central Texas, given the 4-10+
inches of rainfall that fell across the weekend. Since last Thursday, Camp
Mabry has picked up 6.03 inches of rainfall, with the majority of that rainfall
falling on Saturday as the remnant mid and high level moisture of Hurricane
Patricia interacted with a strong upper level storm system, a surface cold front,
and plentiful amounts of low-level Gulf of Mexico moisture. Saturday had the
potential to be a lot worse across the area. Austin Bergstrom International
Airport received 7.55 inches since Thursday, with the majority of that rainfall
falling on Saturday. Thankfully we received more benefits from the rainfall than problems. The Hidden Pines Fire was effectively squashed out, area creeks, rivers, and lakes feeling nice rises, and a nice drop in temperature and humidity across the area.
Below is a look at what Doppler radar imagery looked like at 5:30 a.m. Saturday morning, notice the very heavy tropical downpours extending from Kendall, Blanco, Travis, Williamson and Milam Counties...those heavy downpours exploded over a southward-moving cold front. Thankfully that line of heavy downpours moved through at a time when most people were safely at home and not out on area roadways.
Rainfall Totals across central Texas (past week) courtesy of the LCRA's Hydromet Network:
Generally speaking, 5-12 inches of rainfall fell across Travis County/Austin Metro area with 7-12 inches falling across fire-stricken Bastrop county.
The remnants of
Hurricane Patricia, now known as the “ghost of Patricia,” combined with a
dynamic upper level storm system allowed a strong area of surface low pressure
to develop just off of the Texas coast during the day on Saturday…as that
surface low moved off to the northeast along the Texas coast, the pressure
gradient tightened across south central Texas around the low’s
counter-clockwise rotation, hence the reason for the strong, gusty northerly
winds across the area since Saturday and the nice influx of cool Canadian air
behind the rains. That low is now moving into the southeastern United States
and is creating very gusty winds and widespread precipitation across the
central and eastern Gulf Coast.
With higher
pressure building in from the west, expect a stretch of nice and dry weather
Tuesday through the day on Thursday. Highs will manage to rebound into the 80s
Tuesday and Wednesday with overnight lows generally in the 50s before another
weak front is set to move through the area during the afternoon/evening hours
on Wednesday. Highs drop slightly behind that front on Thursday into the upper
70s to near 80°F thanks to a brief northerly wind shift. Southerly winds look
to return as soon as Thursday night to the area.
Halloween Weekend
Rain Maker (Some stronger storms may be possible):
Okay folks, this
is where things look to get interesting. I’m currently tracking a strong low
pressure system currently located south of Alaska…this system will be digging
southwest toward the west coast of the United States over the coming days and
will eventually approach central Texas as a potent upper level storm system
Thursday afternoon and through the area over the upcoming Halloween weekend.
Moisture will come surging back into the area late Thursday into Friday ahead
of the approaching trough, or atmospheric valley, of low pressure as upper
level divergence increases across Texas. This upper level divergence creates
favorable conditions for showers and storms across our area as early as
Thursday night through Halloween. As of now, we have the potential to see
several rounds of showers and storms across the area. While moisture levels
will not be nearly as high across the area as they were this past weekend, they
will still be plenty high to create the potential for heavy rainfall. The forecast
strength of this approaching storm system and the strong southwesterly wind
flow, and upper air divergence out ahead of it will work together to give us a
good chance for showers and storms. Given the potentially dynamic nature of
this system, the threat for a few stronger/marginally severe storms may be
possible with small to moderate hail, gusty winds, and deadly cloud to ground
lightning being the main threats. Still quite a bit of uncertainty on this
system, however, we will begin to have a better grip and understanding of what
lies ahead for us in the coming days. Please stay tuned to the latest forecast
and understand that this upcoming weekend has the potential to be quite
wet/stormy across the area.
500mb Height Map showing upper level vorticity, or spin in the atmosphere...the red/yellow blob over Louisiana and Mississippi is this past weekend's storm system, the mess south of Alaska is our next storm system! Pretty cool, huh?
Very early
rainfall accumulation forecasts are estimating an additional 1-3 inches of
rainfall may be possible across the area.
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