Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Fort Worth Texas
1000 PM CDT Monday Jul 6 2015
robust complex of thunderstorms is ongoing across parts of
Oklahoma and West Texas tonight with high cloudiness from these
storms now spreading into North Texas. Main concern for the
overnight hours will be how far south this cluster of
thunderstorms pushes. The storms are closely tied to a surface
frontal boundary which is positioned from northwest of Wichita
Falls to northeast through the central part of Oklahoma. There was
a fairly substantial temperature gradient across this boundary
earlier this afternoon and weak forcing for ascent from a passing
shortwave which helped sustain convection well into the evening.
The upper air pattern is not real favorable for this frontal
boundary to continue to push southward so the complex would have
to be driven southward by a well established cold pool. While this
may occur over the next couple of hours...surface based
instability becomes nearly non existent as you get into North
Texas. This suggests that the line of storms will weaken
considerably as it continues to push south and east in the absence
of any other sustained forcing mechanism. Latest indications by
the high resolution guidance also show this weakening trend.
Despite the tendency for the line to weaken...will go ahead and
raise probability of precipitation a bit across the far northwest counties as it is likely
that they will see at least some rain late tonight into early
Tuesday morning. Likewise...have added some low probability of precipitation a little
farther east toward the early morning hours Tuesday. No other
significant changes made at this time except to makes skies mostly
cloudy with the extensive high clouds that will likely move over
in the next few hours.
/issued 652 PM CDT Monday Jul 6 2015/
concerns...MVFR stratus at Waco and the metroplex taf sites once
again overnight tonight through late morning Tuesday.
Deep southerly flow will allow stratus that will form over south
Texas tonight...to move northward into the Waco area around 08z
and into the metroplex around 10z. Expect MVFR ceilings to then
hold in through 16z when deeper vertical mixing should result in a
return to VFR conditions.
Although the gusts should be on the decrease toward sunset...
sustained winds of 15-18 knots will prevail this evening through
the overnight hours. The pressure gradient Tuesday is not expected
to be quite as strong as today...so south winds around 15 knots
are forecast with gusts around 22 knots /versus todays gusts
around 30 knots/.
A cold front that extended just north of a line from kama
/Amarillo Texas/ to kwdg /Enid Oklahoma/ may sink southeast
of a kokc /Oklahoma City/ to ksps /Wichita Falls/ to kmaf
/Midland/ line Tuesday before stalling. The scattered to numerous
showers and thunderstorms that were near this front and also
across much of West Texas will remain northwest of a kmkn
/Comanche Texas/ to kdto /Denton/ to kprx /Paris/ line
through 00z Wednesday.
Previous discussion... /issued 303 PM CDT Monday Jul 6 2015/
couple of days is a trough currently running through the central
part of Canada into the northern United States. Another feature that
will impact the weather in North Texas is a cold front which is
currently located across Nebraska and into Oklahoma and the Texas
pan handle. The breezy conditions that will continue into this
evening are the result of a tightened pressure gradient ahead of the
front. There is a lot of low level moisture ahead of the
front...this creates a concern for flash flooding. This moisture
reaches all the way from the northern plains to North Texas and
can be seen on the upper air sounding from this morning.
Today there is middle level ridging over north and central Texas...this
ridge will begin to break down tonight. It will continue to
deteriorate over the next two days as the trough builds
south...and moves east. This will allow the front to drop south.
How far south and where it stalls will determine the impact it
has on North Texas. Based on the current speed of the front being
fairly close to the latest NAM and European model (ecmwf) model runs...the front
will most likely stall near the Red River. It will likely be near
the northwestern border of the County Warning Area overnight
tonight. The northwestern counties will start to see showers and
thunderstorms develop overnight...but the best chance will be
Tuesday afternoon through Wednesday morning. The main concern with
this convection as previously mentioned will be heavy rain. This
is due to the front becoming nearly stationary and having abundant
low level moisture in place with more on its way. Have held off on
issuing a flash flooding watch at this time...but will continue to
monitor the potential for flash flooding to occur in the
northwestern counties. Severe weather is unlikely...but a few
strong storms with gusty winds are possible. Temperatures will be
a degree or two cooler than what they have been lately on Tuesday
and Wednesday. Lowered temperatures a few degrees in the northwest
counties for those days due to effects of precipitation.
By Thursday a more typical Summer time patter will return with an
upper level ridge starting to build back in...and continue to
build through early next week. The forecast is dry during that
time...with a warming temperature trend. Winds will generally be
southerly and 10 to 15 miles per hour.
Preliminary point temps/pops...
Dallas-ft. Worth, Texas 78 92 78 92 76 / 20 20 20 20 5
Waco, Texas 76 91 76 92 74 / 5 10 10 5 5
Paris, Texas 75 90 75 89 74 / 5 30 30 20 5
Denton, Texas 77 91 75 89 74 / 20 30 30 30 5
McKinney, Texas 77 91 76 90 74 / 20 30 20 20 5
Dallas, Texas 78 94 78 92 76 / 10 20 20 20 5
Terrell, Texas 77 91 75 92 74 / 5 20 10 10 5
Corsicana, Texas 77 92 75 92 73 / 5 10 10 5 5
Temple, Texas 76 91 76 92 74 / 5 10 10 5 5
Mineral Wells, Texas 76 90 73 89 73 / 20 40 40 20 5