Scientific Forecaster Discussion
fxus64 kcrp 202002
Area forecast discussion
National Weather Service Corpus Christi Texas
302 PM CDT Fri Sep 20 2019
Short term (tonight through Saturday night)...
A mid/upper level high pressure system centered across the southeast
US, has its axis draped across East Texas to south Texas. This is keeping
the current isolated shower/thunderstorm activity from becoming more
scattered due to some weak subsidence aloft. The ongoing activity is
expected to diminish this afternoon and evening across the brush
country and inland coastal plains with the loss of instability, then
redevelop over the waters overnight into early Saturday morning due
to coastal convergence. The Saturday morning convection is then
expected to shift inland through the day Saturday along the sea
breeze. The showers/thunderstorms may be a little more scattered
Saturday due to a weak mid level short wave that is progged to track
west across S Texas along the southern periphery of the high pressure.
The short wave combined with 2 inch pwats, convergence along the sea
breeze and instability may produce more lightning and possibly wind
gusts to 30-40 mph. The convection is then expected to diminish once
again Sat evening then redevelop over the waters late Sat night.
Slightly above normal temps are expected to continue through the
Saturday with brief heat indices of 105-109 as the sea breeze moves
inland in the afternoon.
Long term (sunday through thursday)...
An elongated upper ridge axis over much of the Gulf Coast states on
Sunday will steadily wear down and become displaced into the central
Gulf by midweek. Although none of the stronger troughs responsible
for this feat will impact south Texas, models agree nicely in a weak
easterly wave reaching the far western Gulf on Monday along the
periphery of the ridge. This wave should bring improved precip
chances for portions of south Texas on Monday before shearing apart
thereafter as pwats plummet to 1.2 to 1.5 inches. Pops were scaled
lower for Tue and Wed given this drier air mass, but by late week
some moisture recovery looks to unfold ahead of a trough ejecting
out of the Desert Southwest. The GFS is more bullish and farther
south with this trough than the ECMWF, but we'll side with a
compromise for now which keeps this trough and its modified Pacific
well away from south Texas. Temps at 850 mb show only minor
variations through next week, so in general temps look to hold
within a couple degrees of normal.
Onshore winds this afternoon have become marginally strong across
the bays and nearshore waters south of Port Aransas in response to a
tigher pressure gradient between low pressure across West Texas and
Mexico and high pressure across the northern Gulf. Therefore a
Small Craft Advisory was issued for those marine areas. The flow
is expected to decrease to moderate levels this evening as the
gradient slightly relaxes. A weak to moderate...at times
moderate...onshore flow along with isolated to scattered showers
and thunderstorms are expected through Saturday and Saturday
night. Onshore flow will be weak to moderate from Sunday through
next week. Isolated to scattered showers and thunderstorms are
expected each day within a very moist and unsettled regime. A weak
easterly wave arriving on Monday could generate a greater
coverage of showers and storms.
Preliminary point temps/pops...
Corpus Christi 78 94 76 91 76 / 20 30 20 20 10
Victoria 76 93 74 92 74 / 10 30 20 30 10
Laredo 77 100 76 97 76 / 10 10 10 0 0
Alice 77 97 75 94 74 / 10 30 10 20 10
Rockport 81 92 80 89 79 / 20 30 20 20 20
Cotulla 77 101 75 98 75 / 10 10 10 0 0
Kingsville 77 96 76 94 75 / 20 30 10 20 10
Navy corpus 81 92 80 88 80 / 30 30 20 20 20
GM...Small Craft Advisory until 10 PM CDT this evening for the
following zones: bays and waterways from Baffin Bay to Port
Aransas...coastal waters from Baffin Bay to Port Aransas
out 20 nm.