#1571 Postby weatherdude1108 » Fri Aug 25, 2017 12:38 pm
000
FXUS64 KEWX 251635 AAA
AFDEWX
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
1135 AM CDT Fri Aug 25 2017
.UPDATE...
Harvey is slowly moving northwestward in the Gulf of Mexico,
currently as a strong category 2 hurricane, and continuing to
strengthen as it approaches the Texas coastline. This northwestward
movement is expected to continue and Harvey should make landfall
late tonight/Saturday morning. Confidence remains high in a major
rainfall event taking place across much of South Central Texas, in
addition to some locations closer to the coast experiencing hurricane
force and tropical storm force winds.
At this stage, a life-threatening and catastrophic heavy rainfall
event appears imminent for much of South Central Texas east of
Interstate 35 and Interstate 37. This could lead to significant flash
flooding across these areas. Average storm total rainfall amounts of
10 to 20 inches are expected east of Interstate 35 and Interstate
37 today through Tuesday. Isolated higher amounts in excess of
25 inches are possible near and south of the Interstate 10 corridor.
For the Interstate 35 corridor and the eastern Hill Country, including
the cities of San Antonio and Austin 6 to 12 inches are forecast with
isolated higher amounts.
Harvey is expected to stall or move very slowly over the area. With
these forecasted rainfall amounts catastrophic river flooding is also
very likely east of Interstate 35 and south of Interstate 10 in the
Colorado, Guadalupe, and San Antonio river basins.
Additionally, hurricane force winds of 70 to 80 mph will be possible
for the counties within the Hurricane Warning. 40 to 50 mph winds with
some gusts to 60 mph, in the tropical rain bands, will be possible for
areas within the Tropical Storm Warning including San Antonio and San
Marcos. The Austin area could see winds of 20 to 30 mph with gusts to
40mph within rain bands. The timing of these winds look to arrive
as early as Friday afternoon through Saturday morning. There is a low
risk of brief tornadoes east of Interstate 35 and south of Interstate
10 Friday evening into the weekend associated with tropical rain bands.
...Happening now and future forecast through this evening...
Current radar images show rain bands already affecting the middle to
northern part of Texas coast. These rain bands are expected to
produce heavy rain across the coastal plains and southeast counties
this afternoon before tropical storm force winds arrive late this
afternoon or early evening to the middle Texas coast. These rain
bands could produce isolated and quick tornadoes as they move inland
across the southeast part of South Central Texas.
Weather conditions will deteriorate late tonight into Saturday as
Harvey makes landfall. A long period of Heavy rain is expected across
South Central Texas late tonight through early next week. This is a
a life-threatening and catastrophic heavy rainfall event, especially
for areas east of Interstate 35 and Interstate 37.
Please see our key messaging points for this event:
1) A life-threatening and catastrophic heavy rainfall event is
expected east of I-35 and I-37.
2) Average rainfall amounts of 10-20 inches are expected east of
I-35 and I-37 Today through Tuesday.
3) Isolated higher totals in excess of 25 inches are possible near
and south of the I-10 corridor.
4) Along the I-35 corridor and across the eastern Hill Country,
including the City of San Antonio and Austin, 6-12 inches with
isolated higher totals are possible.
Additional important notes:
a) Small shifts in the forecast track of Harvey and where it stalls
this weekend could result in very large differences in rainfall
totals.
b) Catastrophic mainstem river flooding lasting many days is
possible east of I-35 and I-37 in the Colorado, Guadalupe, and San
Antonio river basins.
c) Tropical Storm Force winds arriving as early
as of this afternoon in rain bands.
d) 70-80 mph winds are expected for counties in the Hurricane Warning.
f) Large trees could be snapped, power lines downed, and damage
to homes could occur. Power and communication outages are likely.
e) 40-50 mph winds are expected within the area now under
a Tropical Storm Warning with gusts to 60 mph in rain bands.
This includes San Antonio to San Marcos areas. Damage to
trees and power lines are possible, leading to scattered power
outages.
g) For Austin 20-30 mph with gusts in excess of 40 mph in rain
bands.
h) There is a marginal risk for tornadoes east of a I-35 and I-37
this afternoon through Saturday. These small tornadoes are typically
very fast moving and short-lived.
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The preceding post is NOT an official forecast, and should not be used as such. It is only the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org. For Official Information please refer to the NHC and NWS products.
