139 
fxus64 kcrp 200447 aac 
afdcrp 


Area forecast discussion...updated 
National Weather Service Corpus Christi Texas 
1147 PM CDT Friday Mar 19 2010 


Discussion...updated for 06z taf issuance below. 


&& 


Aviation...ample low level moisture combined with low level jet dynamics will 
contribute to MVFR ceiling development over south Texas tonight. The 
southerly low level jet will also continue to generate non-convective low level wind shear 
over the region tonight with 1000ft winds generally around 30 knots. 
However...as a strong cold front approaches...the height gradient 
will slacken thus weakening the low level jet out west around 08z...and across 
the coastal plains between 11z-12z. The cold front is expected to blast 
through klrd around 15z...and move east through the coastal taf 
sites between 17z-19z. Showers and thunderstorms associated with the 
front should briefly impact the terminal aerodromes across the 
coastal plains...especially kvct around midday. Strong northwesterly 
winds will develop areawide behind the front...with wind gusts 
between 35-40 knots expected across south Texas by Saturday 
afternoon. 


&& 


Previous discussion... /issued 955 PM CDT Friday Mar 19 2010/ 


Discussion...updated the forecast package to increase probability of precipitation 
associated with the front tomorrow across the northeast County Warning Area based 
on recent model data. Otherwise...the main issue for the short 
term forecast will be the wind. Winds over the coastal waters are 
expected to remain below Small Craft Advisory conditions overnight. However...seas 
60 nm offshore are expected to increase to around 7 feet. As a 
result...cancelled the Small Craft Advisory in effect for the bays and nearshore 
waters tonight and forecasted scec conditions. However...decided 
to maintain the Small Craft Advisory 20 to 60 nm offshore due to the expected 7 feet 
wave heights. 


The cold front is still expected to blast through the brush 
country Saturday morning...then through the coastal counties and 
offshore Saturday afternoon. The GFS/NAM forecast 925mb winds to be 
between 30-35 knots during the afternoon hours. Wind Advisory 
conditions will be likely...but will hold off on its issuance due 
to areal uncertainty. However...the Fire Weather Watch was 
upgraded to a red flag warning for the brush country tomorrow 
afternoon. In addition...upgraded the gale watch to a Gale Warning 
for the Gulf waters 20 to 60 nm offshore late Saturday afternoon 
through Saturday night. Updated gridded and text products have 
been sent. 


Previous discussion... /issued 647 PM CDT Friday Mar 19 2010/ 


Discussion...see aviation section for 00z tafs. 


Aviation...gusty southeast winds over the coastal Bend expected 
to diminish by 02z-03z timeframe. Southerly low level jet will be 
35-40 knots leading to stratus developing over the brush country 
around 06z and spreading eastward toward the coastal Bend by 
daybreak. A strong cold front will move into the brush country 
around 14z and advance toward the coast by 19z-20z. Scattered to 
numerous showers/isolated thunderstorms will be possible to the 
northeast of a Corpus Christi to Pleasanton line. MVFR visibilities in 
showers are anticipated but IFR ceilings/visibilities will be possible with 
the stronger showers and T-storms. Conditions will improve to VFR 
quickly behind the front but northwest winds will be strong with 
gusts to around 35 knots areawide by 20z-21z. 


Previous discussion... /issued 334 PM CDT Friday Mar 19 2010/ 


Short term (tonight through Saturday night)...strong low level 
flow out ahead of a late-season cold front will continue into the 
early evening. Wind Advisory in effect will be continued until 8 
PM across the southern coastal Bend...and inland as far as kali. 
Winds elsewhere will be elevated...just not to advisory criteria. 


Surface flow will diminish overnight as moisture return leads to skies 
clouding over late tonight. Focus then turns to cold frontal 
passage itself. Front expected to push through the Rio Grande 
plains and brush country Saturday morning...progressive 
southeastward through the day and clearing the County warning forecast area by middle- 
afternoon. Impressive dynamics will be offset by mediocre moisture 
return across the west...but better inflow over the east will lead 
to better coverage of mainly light precipitation. Those same 
dynamics and slight instability means thunder is also possible 
over the east...although not enough for any significant severe threat. 


Winds will again pick up behind the front as dry Arctic air pushes into 
the region. This should shut off precipitation relatively quickly 
after frontal passage...but may again reach Wind Advisory criteria 
across south Texas. Very dry air in the wake of the front will 
create an elevated fire danger out west where skies will clear 
relatively early in the day...and with gusty winds and low 
relative humidities a Fire Weather Watch for those areas remains 
warranted. 


Local low level winds set up favorably for cooling late Saturday 
night into Sunday morning...and lows Sunday morning will fall 
into the 30s in many locations across the coastal Bend as a 
result. 


Long term (sunday through friday)...main forecast issues are the 
temperatures early in the period...then the chances for rain 
around middle week. Pretty much status-quo from what has been 
forecast for the past couple of days...with only exception being a 
slowly moving surface high on Monday...meaning cooler than 
expected temperatures and less time for return flow to come back 
in time for the next upper system still forecast to move mainly 
north of the area. Thus...basic changes to previous thinking 
(generally minor ones) have been to lower temperatures a bit 
Sunday morning...a bit more Monday morning...and increase winds 
for Sunday. For the rain chances on Wednesday...went no more than 
low chance probability of precipitation for Wednesday with the lower moisture profiles. 
However... moisture does hang around for Thursday with pre-frontal 
trough and with enough instability...sea breeze and daytime 
heating...did keep probability of precipitation in (again no more than low end chance) for 
Thursday. European model (ecmwf) is faster with front than GFS...but went more 
toward the GFS this time with slow upper trough. With timing of 
front slightly different... adjusted temperatures accordingly and 
generally due to these timing issues die not stray too far from 
guidance after Tuesday. 


&& 


Preliminary point temps/pops... 
Corpus Christi 61 71 37 69 36 / 10 50 10 0 0 
Victoria 57 64 32 63 33 / 10 80 10 0 0 
Laredo 64 72 39 74 41 / 10 20 0 0 0 
Alice 59 72 37 71 36 / 10 50 0 0 0 
Rockport 61 70 41 66 42 / 10 60 10 0 0 
Cotulla 58 66 33 71 35 / 20 30 0 0 0 
Kingsville 60 74 37 73 35 / 10 40 0 0 0 
Navy corpus 63 70 41 67 42 / 10 50 10 0 0 


&& 


Crp watches/warnings/advisories... 
Texas...red flag warning from 1 PM to 9 PM CDT Saturday for the 
following zones: Duval...Jim Wells...La Salle...Live Oak... 
McMullen...Webb. 


GM...Small Craft Advisory until 7 am CDT Saturday for the following 
zones: waters from Baffin Bay to Port Aransas from 20 to 60 
nm...waters from Port Aransas to Matagorda Ship Channel 
from 20 to 60 nm. 


Small Craft Advisory from 5 am to 10 am CDT Sunday for the 
following zones: waters from Baffin Bay to Port Aransas 
from 20 to 60 nm...waters from Port Aransas to Matagorda 
Ship Channel from 20 to 60 nm. 


Gale Warning from 4 PM Saturday to 5 am CDT Sunday for the 
following zones: waters from Baffin Bay to Port Aransas 
from 20 to 60 nm...waters from Port Aransas to Matagorda 
Ship Channel from 20 to 60 nm. 


Small Craft Advisory from 4 PM Saturday to 5 am CDT Sunday for 
the following zones: bays and waterways from Baffin Bay to 
Port Aransas...bays and waterways from Port Aransas to Port 
O'Connor. 


Small Craft Advisory from 4 PM Saturday to 10 am CDT Sunday for 
the following zones: coastal waters from Baffin Bay to Port 
Aransas out 20 nm...coastal waters from Port Aransas to 
Matagorda Ship Channel out 20 nm. 


&& 


$$ 


Tm/95...aviation/update 

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