At 1700 the stalled sfc front was located just south of a Hamilton to
Sulpher Springs line with 1km satellite showing well defined convective
circulations along the front.Temps South of the front were in the upper
80s to near 90 with cool...cloudy and moist 70s north of the front.
In the upper levels there are a number of features that will impact our
weather going forward...one is a tropical wave in the Bay of Campeche...
another is a tropical disturbance at the tip of Baja California...and third
is a mid-latitude shortwave diving down out of MT. On satellite...a convective
cluster of storms is moving out of the South Plains while it appears another
cluster is trying to form across parts of the Concho valley into the Big
Country. This is likely due to a weak wave embedded within the upper flow
emenating out of Chihuahua from the moisture feed of Odile.
Through the remainder of the diurnal heating cycle expect the front to move
very little without the aid of upper support. The combination of a somewhat
cool and moist boundary layer north of the front and a warm mC airmass south
of the front will create quite a temp discrepncy during the peak heating hours
...with temps south of the boundary heating into the mid to upper 90s and temps
in the upper 70s to near 80 north of the boundary. Precip chances today with
the front will mainly hinge on mesoscale convergence and solar heating as upper
support will be nill till after sundown. A secondary area of precip is possible
across the western zones with the wave discussed above. Models haven't picked up
on this feature but a moist column is in place so any wave/source of lift will result
in showers and storms with threat of heavy rainfall. Will go 30 pops about 30 miles
either side of the front as SPC mesoanalysis is still showing noteable moisture
convergence along the boundary and short term hi-res guidance does show a broken line
of showers and storms along a Goldthwaite to Waco to Palestine line much like we saw
yday in the NW zones. Main threat with these showers will be locally damaging winds
from microburts. Expect these cells to die off with the lost of daytime heating.
Will go 30 pops as well across the western and northwestern zones for any showers
and storms that develop there in the afternoon. Expect anything out west will be
scattered at best. Will keep an eye on this throughout the day and amend the forecast
Overnight the threat for heavy rainfall and potential flooding...mainly across
the southern zones...will increase due to a combination of several factors...
mainly being column moisture being 2 to 3 standard deviations above normal.
This moisture will come from the 2 tropical disturbances mentioned above. Lift
will come in the form of the aforementioned shortwave that will lead to isentropic
ascent along and north of the boundary. 850-700 flow will be nearly parallel to
the boundary so flash/flooding is/will be a concern during the overnight hours
into Friday morning. Large scale lift will begin to spread west to east from the
High Plains into North Texas with the aid of the shortwave approaching the region.
Hi res guidance such as the TT WRF show this well with large swath of precip
developing across the high terrain of West Texas late tonight. Have decided against
a Flash Flood Watch as (1) the upper wave will slide more through Central Plains and
(2) a lack of more robust instablity/lapse rates. For those weather
geeks this setup is not all unlike that of a winter storm just without the Arctic
By midday Friday the upper wave will begin ejecting out which will result in the 850
front being shunted through the region thus ending precip northwest to southeast. While
this will end precip it will not make for a beautiful crips Fall weekend unfortunately. Upper
pattern will continue to be progressive which means the sfc high will move more east than
south into the Southern Plains. This will result in continued weak moist flow as boundary
layer winds slowly veer from northeasterly Saturday morning to southeasterly Sunday moring.
This will keep moisture trapped in the boundary layer for Saturday resulting in considerable
overcast skies and thus cool temps in the 70s for much of the day. Will likely see more sun
on Sunday as return flow off the Gulf commences along with a warm up. Highs will climb back
into the 80s on Sunday. Temps into the first part of next will return to seasonal norms
with highs in around 90 and an upper pattern that is more summer like with a series of low
amplitude waves propogating through the northern tier of states.