Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Fort Worth Texas
855 PM CDT Wednesday may 6 2015
new Tornado Watch #137 issued for Young...Jack...and Montague
counties through 2 am CDT. This is mainly for the supercell
entering SW Throckmorton County...as the Archer County storm
should affect Clay County...but remain mainly west of Montague
County. We expect the main threat to last through midnight and
going by any unforeseen changes amongst the high-resolution
models...we would think the watch could be canceled early by a few
hours. We continue to monitor the Throckmorton storm which has
shown weakening trends the past 5-10 minutes.
/issued 704 PM CDT Wednesday may 6 2015/
Concerns...thunderstorms to the northwest...MVFR stratus.
The Bowie cornerpost has remained open...but severe thunderstorms
will continue to disrupt northwest arrivals this evening. The
activity is unlikely to get much closer to metroplex airspace.
A 30-35kt low level jet will feed Oklahoma storms and in the process will
saturate the layer beneath an 850mb cap. The result will be MVFR
stratus arriving by midnight. Think MOS is too pessimistic with
IFR ceilings in the metroplex...thus will maintain MVFR overnight
and throughout Thursday morning. (Tempo IFR may occur again at
VFR ceilings will likely prevail again on Thursday afternoon. Weak
ripples in southwest flow aloft will maintain low shower/storm
chances...but will not include any mention in the tafs.
best forcing will remain just off the northwest edge of our County Warning Area...but
still have to watch for supercell splits and possible right movers
for Stephens...Young...Jack...Montague counties. We plan to hold
these counties in Tornado Watch 135 until expiration at 9 PM.
The remainder of the counties...including Eastland...Palo
Pinto...Parker...and wise have been removed at the watch.
High res models are showing discrete storms across far West Texas and
the Permian Basin possibly becoming a linear mesoscale convective system and entering far
western North Texas after 3 am. A low threat for severe storms with
damaging winds...marginally severe hail...and heavy rainfall will
be possible with late night/early Thursday morning activity across
western North Texas. This activity should move toward the northern
I-35 corridor...including the dfw metroplex by daybreak...but are
expected to weaken with a veering and weakening low level jet.
Previous discussion... /issued 248 PM CDT Wednesday may 6 2015/
Tornado Watch 133 is in effect along and west of a Nocona to
Weatherford to Cisco line through 8 PM this evening. Storms are
developing along a Lawton to Sweetwater to Junction line where the
air mass is very unstable with very high cape and enough helicity
for supercell development and isolated tornadoes. Have increased
probability of precipitation across this area through this evening. Elsewhere...late
afternoon convection should favor areas generally east of I-35 like
yesterday with a decrease in activity by 10 PM.
We will continue to maintain 20-50 probability of precipitation over the region for
Thursday through Friday night before things gear up over the
weekend. Another deep upper low will move through the Desert
Southwest Friday and into the Central Plains Sunday night. This
system will spread strong forcing for ascent and upper diffluence
across the region over the weekend. Also...there will be deep low
level moisture in place over the region with precipitable waters around 1.90
inches. Thus...we expect considerable thunderstorm activity both
Saturday and Sunday with a potential for severe storms and heavy
rainfall that could result in flash flooding problems and river
rises...especially on Sunday.
As the upper low moves through the Central Plains Sunday night...a
cold front will sweep through North Texas early Monday and around
middle central Texas on Monday morning. There will be some convection
along the front that will move south with it. However...we will
maintain chance probability of precipitation generally south of I-20 on Tuesday.
There are some discrepancies between the European model (ecmwf) and GFS concerning
how far south the front GOES...how fast it returns and
precipitation next week. The GFS seems to be the outlier when
compared to the European model (ecmwf) and Canadian models...thus have weighted the
middle week forecast toward the more consistent models which keep
the cold front to the south Tuesday through Wednesday before
bringing it back north. 75
Preliminary point temps/pops...
Dallas-ft. Worth, Texas 68 82 69 81 70 / 30 40 30 40 40
Waco, Texas 69 82 69 83 70 / 20 30 30 40 30
Paris, Texas 66 79 68 81 69 / 20 40 30 30 50
Denton, Texas 67 81 69 80 69 / 40 50 40 40 40
McKinney, Texas 67 80 69 80 69 / 20 40 30 40 40
Dallas, Texas 68 83 69 82 70 / 30 30 30 40 30
Terrell, Texas 68 82 68 82 69 / 20 30 30 40 30
Corsicana, Texas 68 82 69 83 70 / 20 30 30 40 30
Temple, Texas 70 83 69 83 70 / 20 30 20 40 30
Mineral Wells, Texas 67 80 68 80 69 / 40 50 40 50 40