Wildfire in Texas, July 11 to 17, 2020

Area Forecast Discussion
National Weather Service Amarillo TX
1239 PM CDT Sat Jul 11 2020

.AVIATION...
VFR conditions expected for the majority of the 18Z TAF period.
VCTS conditions may start as early as 01-02Z Sunday and continue
through 06-07Z before storms dissipate. Only about a 20 percent
chance at this time. Winds have already shifted to northerly
behind front at KDHT/KGUY with SW winds currently at KAMA. Winds
will shift to northerly behind front sometime after 02Z Sunday for
KAMA. Some sct low clouds possible for KGUY towards sunrise
Sunday morning, but should quickly dissipate by the end of the TAF
period with mostly clear skies.

Meccariello

&&

PREV DISCUSSION... /Issued 329 AM CDT Sat Jul 11 2020/

SHORT TERM...Today and Tonight...

Current WV satellite reveals a large scale upper
ridge over NM with several mesoscale convective systems rolling
across the central Plains states on the northeastern edge of this
feature. At the surface, after remnant outflow boundaries from
Friday morning's MCSs to our north and east led to a complex wind
field across the Panhandles Friday afternoon, generally southerly
winds are present.

For today, upper ridge continues to dominate the weather pattern
with hot temperatures expected. Forecasting exact highs is a
challenge, as northern stream disturbance that kicked off the
ongoing MCSs to our northeast will push another northerly surface
wind shift through at least the northern half of the CWA this
afternoon, likely holding back these areas just a bit. Along and
south of this boundary, downslope west-southwesterly winds, combined
with very warm temperatures aloft will lead to another dangerously
warm afternoon. Regime is reminiscent of Thursday, when
NBMEXP was the best consensus performer but still undercut
temperatures south of the boundary that pushed south that
afternoon and overdid them a bit to the north. With the boundary
hanging up in a similar location, started with NBMEXP and trended
temperatures using average GFS/NAM/ECE MOS errors from Thursday
afternoon. Dangerously hot temperatures will result across the
southern Texas Panhandle, where a Heat Advisory has been issued,
including areas off the caprock, where southerly winds should
advect enough moisture to push heat indices up above 110 even if
temperatures do not quite get there. Have also gone with an Excessive
Heat Warning for Palo Duro Canyon, where temperatures could top out
at 116.

Finally, there will be a conditional chance for thunderstorms both
along the convergent zone along the boundary and in the upslope flow
region across NE NM if the cap can be overcome. Guidance does
generally depict a weak upper disturbance rotating around the edge of
the upper ridge, so do think the cap eroding will be a possibility.
Given progged MLCAPE of 1000-2000 J/kg and DCAPE of around 2000 J/kg,
any storm that develops will be capable of generating damaging wind
gusts. However, with 0-6km bulk shear values of only 20-30 knots, do
not expect organized convection. Sagging boundary will also provide a
reservoir of surface vorticity across the Texas Panhandle but, with
0-3km MLCAPE less than 50 J/kg due to very high cloud bases, the risk
of a stray landspout occurring under any updrafts that develop will
be low.

Tonight, with light easterly winds in place across the CWA, should
actually see a bit of relief as temperatures fall into the lower 70s
in most locations. If thunderstorms develop during the evening,
could get some low clouds developing in some locations - expect
cool outflow to allow temperatures to drop anyway even if low
clouds hinder radiational cooling conditions.

Ferguson

LONG TERM...Sunday through Friday night...

Mid to upper level high pressure will continue to dominate the
area bringing hot temperatures in the extended forecast. The H5
ridge may bring some precipitation to the area with northwest
flow on Sunday then some shortwaves riding the ridge Monday night
through Friday night. Only 20 to 30 PoPs exist as of now with the
western FA favored on some of those nights.

Tomorrow, the H5 ridge will be positioned over AZ and NM such
that the combined Panhandles will be under northwest flow. By
Sunday morning a surface boundary that has been laid up over the
area dividing the northwest and southeastern FA will have pushed
through the rest of the Texas Panhandle. This will cause winds to
gradually shift from the north-northeast to the southeast by the
end of the day. These surface winds will be upsloping creating
cooler temperatures along with dewpoints in the upper 50's to
60's. Models have been coming in cooler than previous runs with
highs in the upper 90's to 105. Mos guidance guidance suggest
Amarillo will only reach 92 to 94 degrees. Therefore, with the
upslope winds and MOS guidance have lowered temperatures a few
degrees from NBM and have Amarillo forecasted at 95 degrees Sunday
afternoon.

A perturbation in the northwest flow aloft will help bring in
thunderstorms from the mountains Sunday evening and into the
overnight hours. Have stayed with NMB PoPs which have a
widespread 20's to 30's across much of the FA but may still be
too low. PWAT values range from 1.4 inches in the west to 1.6
inches in the eastern FA which are well above the 90th percentile.
Therefore, some localized flooding could be of concern with any
storms that do form. Also, severe thunderstorms will be a
possibility for the western FA Sunday evening. Models suggest
MUCAPE values ranging from 2500 to 3500 J/Kg with Effective
Bulkshear ranging from 25 to 35 knots. DCAPE values look to be
anywhere from 1000 to 1500 J/Kg. H5 temperatures are a bit on the
warm side with NAM coming in with -5 to -6 degrees and GFS coming
in with -6 to -7 degrees.

Monday, the H5 high pressure moves east a little and the ridge
flattens out a little. Some perturbations in the flow aloft may
allow for some isolated to scattered thunderstorms again on Monday
evening with the western FA favored. Surface winds will become
southwest once again with downsloping winds aiding in heating.
Daytime temperatures are forecasted to be in the 102 to 110 range
because of this. Some highlights may be needed especially for Palo
Duro Canyon and Canadian River Valley.

Tuesday another frontal boundary will lay up across portions of
the northwest FA which will hold temperatures back with northerly
winds and create a temperature gradient from the northwest to
southeast across the combined Panhandles. Evening thunderstorms
will be possible again with 20 to 30 PoPs in the forecast across
most of the FA. By Wednesday the NBM suggest the surface boundary
will move through the entire area so that most of the area sees
daytime highs in the upper 90's and not the triple digits. The
rest of the extended looks very similar with daytime highs in the
upper 90's with triple digits in lower lying areas such as Palo
Duro Canyon and the Canadian River Valley.

Hoffeditz

&&

.AMA Watches/Warnings/Advisories...
TX...Heat Advisory until 9 PM CDT this evening for the following
     zones: Armstrong...Carson...Collingsworth...Deaf Smith...
     Donley...Gray...Hutchinson...Oldham...Potter...Randall...
     Roberts...Wheeler.

     Excessive Heat Warning until 9 PM CDT this evening for the
     following zones: Palo Duro Canyon.

OK...None.

&&

29/2

Hazardous Weather Outlook...CORRECTED
National Weather Service Amarillo TX
339 AM CDT Sat Jul 11 2020

OKZ001>003-TXZ001>020-317-112100-
Cimarron-Texas-Beaver-Dallam-Sherman-Hansford-Ochiltree-Lipscomb-
Hartley-Moore-Hutchinson-Roberts-Hemphill-Oldham-Potter-Carson-
Gray-Wheeler-Deaf Smith-Randall-Armstrong-Donley-Collingsworth-
Palo Duro Canyon-
339 AM CDT Sat Jul 11 2020

This Hazardous Weather Outlook is for the Texas and Oklahoma
Panhandles.

.DAY ONE...Today and Tonight.

Dangerous heat is expected across the southern half of the Texas
Panhandle, where a Heat Advisory is in effect for this afternoon.
Additionally, high temperatures above 110 degrees are expected in
Palo Duro Canyon State Park, where an Excessive Heat Warning is in
effect for this afternoon.

Thunderstorms will be possible late this afternoon and this
evening across the Texas Panhandle. If storms, develop, they
may become severe with damaging wind gusts.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Thunderstorms will be possible Sunday night through Friday night
during the evening to overnight hours. Some thunderstorms on
Sunday may become severe with large hail and damaging winds
possible mainly across the western combined Panhandles. The
chances for widespread severe storms is low at this time Monday
onward.

High temperatures will return on Monday with Heat Advisories and
Excessive Heat Warnings possible for much of the southern Texas
Panhandle.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated at this time.