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Area forecast discussion 
National Weather Service Brownsville Texas 
303 am CDT sun Mar 21 2010 


Short term /today through 7 PM Monday/...wind forecast for today 
will drive sensible weather changes in the short term. Winds off 
the surface 40 to 50 kts this morning will mix downward quickly 
after sunrise keeping breezy conditions up through at least early 
afternoon and allowing drier air to mix down today lowering 
dewpoints further...perhaps into the teens western counties. Temperatures 
will respond nicely in the dry air tempered only by the winds. 
NAM/RUC have solid handle on the boundary layer winds and drier air 
and have tweaked forecast winds to reflect latest runs. 


Atmosphere will decouple after dark allowing winds to go calm with 
excellent radiational cooling on tap. Min temperature records could be in 
danger Monday morning with lows expected near 40 to lower 40s..only 
a few degrees above area records. Southeasterly flow returns late 
Monday heralding a slow moisture and temperature recovery for the 
early week. 


&& 


Long term /00z Tuesday through Sunday/...surface high pressure 
shifting into the Gulf at the beginning of the period will open 
up southeast flow across deep south Texas...putting an end to the 
Bone dry conditions. Next in a series of midlevel troughs will 
sweep across the southwestern US and into Texas Wednesday. 
A couple vorticity maxima caught out ahead of it in the southwest flow 
aloft will bring a slight chance for showers during the day 
Wednesday. Forecast thinking is that most of this energy will 
remain in the western valley...with only light rain/sprinkles for 
the coastal regions. Models beginning to agree on bringing the 
front associated with the midlevel trough through deep south Texas 
during the predawn hours on Thursday. Models also beginning to 
show consistency with pushing the front well out to sea...with 
ever higher breezes with and behind the front. Precipitation is 
still a question mark as dynamics aloft still look weak and well 
away from deep south Texas. Will keep isolated probability of precipitation for the region 
for immediately during frontal passage Thursday...with quick 
clearing in its wake. Temperatures during the extended period 
remain close to normals for this time of year...which is right 
around 80 for highs and 60 for lows. 




&& 


Aviation... 
VFR through 12z Monday. 50 knots flow at 3000 feet this morning will 
support gusty winds briefly after daybreak. Breezy northerly flow 
will diminish slowly through the day today with winds light and 
variable shortly after 00z and continuing overnight. Southeasterly 
flow will redevelop on Monday. 


&& 


Marine... 
buoys gusting well over 30 kts with seas above 11 feet at 
midnight. Winds should decrease slowly through the early morning 
hours allowing Gale Warning for the coastal waters to expire on 
time however conditions will likely remain above Small Craft 
Advisory criteria into the early afternoon. Conditions over the 
Laguna Madre still above Small Craft Advisory criteria and may need to extend a 
little longer through the morning given expected downward 
momentum. Marine conditions will improve through the afternoon. An 
onshore flow will redevelop Monday afternoon...and will continue 
into the latter half of the week. A cold front will move through 
the coastal waters likely around dawn Thursday...switching winds 
to the northwest. Strength of the northwest flow surge still a bit 
questionable but still has a good chance to reach advisory 
strength right as it passes. Seas will remain steady 2 to 4 feet 
until the frontal passage. 


&& 


Fire weather... 
very dry air in place over the Rio Grande Valley today. Surface 
winds while still breezy especially this morning will stay below 
red flag criteria. Relative humidities will begin to recover late 
Monday as a southeasterly flow redevelops. 


&& 


Preliminary point temps/pops... 
Bayview/Port Isabel 69 46 74 57 / 0 0 0 0 
Brownsville 71 45 77 54 / 0 0 0 0 
Harlingen 71 42 79 54 / 0 0 0 0 
McAllen 73 41 81 55 / 0 0 0 0 
Rio Grande City 74 45 83 56 / 0 0 0 0 
South Padre Island 68 52 75 58 / 0 0 0 0 


&& 


Bro watches/warnings/advisories... 
Texas...none. 
GM...Small Craft Advisory until 10 am CDT this morning for gmz130-132- 
135. 


Gale Warning until 10 am CDT this morning for gmz150-155-170-175. 


&& 


$$ 


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