Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Austin/San Antonio Texas
255 am CDT Friday may 29 2015

Short term (today through saturday)...
line of showers and storms is finally showing signs of slowly
weakening as it moves southeast with lightning trends steadily
decreasing. Severe winds were the predominant severe type with
several reports of 60 to 70 miles per hour wind gusts across the western and
northern County Warning Area including Bexar County. Rainfall amounts have been
well behaved because the main line of the heavier storms has been
moving at a decent speed around 40-45 miles per hour. Dual-pol precipitation
estimates show widespread 1-2 inches with isolated spots near 3
inches which is about what we were expecting. This line of
showers will continue to push southeast with lingering stratiform
rain expected to persist for several more hours and will let the
Flash Flood Watch continue until the expiration time at 12z. This
residual rain will allow for precipitation amounts to slowly increase for
the rest of the overnight period and this morning. For
today...left higher probability of precipitation in the forecast for the 12z to 18z time
period to account for the stratiform precipitation and will decrease them
in the afternoon hours. Will have 20-30 probability of precipitation in the
afternoon...with the higher probability of precipitation across the eastern counties where
the best moisture will be. Think the atmosphere will be pretty
well worked over and am not expecting too much activity. The ttu
WRF seems to be initialized well and shows very little activity
after 18z.

We will have to watch northwest Texas once again in the afternoon
for thunderstorm development. It should be a bit less than
yesterday due to the absence of significant upper forcing. A large
trough will be passing through the Central Plains and a cold front
is expected to push south into North Texas. This should be the
focus for thunderstorm development and some models are showing
signs these will try to once again congeal into a line...detach
from the front and move south. Most models keep the bulk of the
activity north of our forecast area until Saturday...when the
actual front makes it. Therefore...the chances of a repeat mesoscale convective system
tonight appears to be low. Probability of precipitation will increase Saturday as the slow
moving front moves into the area. With the boundary...there will
always be a chance of locally heavy rain and that will be our main
concern. However...it is tough to Pin-Point exactly where that
will occur and will only continue to mention it in the severe weather potential statement until
more confidence on timing or an area can be obtained.




&&

Long term (saturday night through thursday)...
higher rain chances will continue Saturday night across the
area with the frontal boundary near the area. The threat for
heavy rain should slowly diminish as as upper low is expected to
stall and be nearly stationary well to our east. This stalled
upper low will allow winds throughout the atmospheric column to be
northerly which generally is not the best for heavy rain. Think we
will see diurnally driven convection Monday through
Thursday...mainly in the eastern zones where moisture will be best
and in closer proximity to the upper low. Also...with the north
flow in the atmosphere...precipitable water values will decrease
to below 1.5 inches for most of the County Warning Area on Sunday and last through
the end of the period. This will also help ensure the waning
threat for heavy rainfall. However...we will have to get through
the weekend first.

&&

Preliminary point temps/pops...
Austin Camp Mabry 86 71 86 67 82 / 40 30 50 50 30
Austin Bergstrom international Airport 85 70 84 66 81 / 40 20 50 50 40
New Braunfels Muni Airport 86 71 85 67 83 / 40 20 50 50 40
Burnet Muni Airport 83 69 82 64 80 / 40 30 60 50 30
del Rio International Airport 88 73 86 68 86 / 20 20 40 50 30
Georgetown Muni Airport 84 70 83 65 81 / 40 30 60 50 30
Hondo Muni Airport 86 72 85 67 84 / 20 20 40 50 40
San Marcos Muni Airport 85 71 84 67 82 / 40 20 50 50 40
La Grange - Fayette regional 86 72 85 67 83 / 50 20 60 50 40
San Antonio International Airport 86 72 86 68 83 / 30 20 50 50 40
Stinson Muni Airport 86 73 86 69 82 / 30 20 50 50 40

&&

Ewx watches/warnings/advisories...
Flash Flood Watch until 7 am CDT this morning for the following
counties: Bandera...Bastrop...Bexar...blanco...Burnet...Caldwell...
Comal...Dimmit...Edwards...Fayette...frio...Gillespie...Guadalupe...
Hays...Kendall...Kerr...Kinney...Lee...Llano...Maverick...Medina...
real...Travis...Uvalde...Val Verde...Williamson...Zavala.

&&

$$

Mesoscale/aviation...04
synoptic/grids...Hampshire

National Weather Service Glossary of Abbreviations