Excessive Heat in Texas, June 17, 2017

Area Forecast Discussion
National Weather Service Lubbock TX
1214 PM CDT Sat Jun 17 2017

.AVIATION...
VFR conditions will persist through at least 06 UTC or later,
However, very hot temperatures at the terminals today will
decrease air density, be sure to check density altitude. A strong
cold front will pass through the terminals Sunday morning. A
period of sustained wind speeds near 30 kts can be expected at
KLBB and PVW and possibly some BLDU. Also, there are some
indications that there could be a period of sub-VFR conditions at
the terminals due to low clouds behind the front. Confidence is
not high enough at his time to add any reductions to the TAFs.

&&

.PREV DISCUSSION... /issued 1120 AM CDT Sat Jun 17 2017/

UPDATE...
Temperatures have already reached the century mark on some West
Texas Mesonet sites across the western Rolling Plains and 24 hr
temperatures changes of plus 5-10 degrees are common across the
entire area. Yesterday saw several locations across the Rolling
Plains exceed 105F. As a result we have upgraded to an Excessive
Heat Warning for the western South Plains today. After
collaboration with OUN/AMA we will not be adding a heat advisory
to the Rolling Plains and remainder of the Panhandle though
temperatures and heat index could approach 110 there.
Afternoon highs had already been bumped up a degree or so in a
previous update and we will monitor trends for more adjustments
early this afternoon.

Very hot temperatures aloft associated with a sprawling ridge of
high pressure centered over southern California and Arizona will
dominate the region today before a much needed cold front sweeps
south on Sunday. Westerly downslope winds seem to also be aiding
the rapid warmup with winds more backed off the Caprock. A thin
veil of cirrus from an MCS over eastern Oklahoma has spread into
the Rolling Plains and combined with higher humidity may be
responsible for the reduced heating there.

PREV DISCUSSION... /issued 629 AM CDT Sat Jun 17 2017/

AVIATION...
VFR. Light S-SW winds today will shift abruptly to the N at 20 to
30 knots after midnight following a strong front moving south.
Shallow moisture behind this front could yield pockets of low
clouds, but nothing organized enough for sub-VFR conditions.

Potential for blowing dust/lower VIS during FROPA is greatest at
LBB given open fields north of the terminal. Strong winds could
flirt with Airport Weather Warning criteria at LBB, even beyond
7 AM Sun.

PREV DISCUSSION... /issued 425 AM CDT Sat Jun 17 2017/

DISCUSSION...
Hot. Even though the center of the ridge will remain just to the
west of the area, thickness values will be at their peak this
afternoon. Record high temperature still looks to be in jeopardy
for Lubbock but a few degrees shy in Childress. Will continue the
heat advisory for the Caprock due to the high temperatures, but
the Rolling Plains will fall a few degrees shy of the actual temp
of 110/heat index of 115 required to be included so will leave
this area out.

The next challenging issue will be the arrival of the cold front
Sunday morning. Models and MOS guidance are all pointing towards a
breezy to possibly windy morning across the South Plains with
35-40 MPH winds possible behind the front. Models are also having
difficulty settling on how much cold air will arrive with the
front. Temperatures range from 82 in the NAM MOS to upper 90s in
the GFS/ECMWF Ensembles. Last several runs have pretty much been
bouncing around the upper 80s for the northwestern half of the
forecast area but have recently dropped the southeastern half back
into the low 90s from the upper 90s. The strength of the front and
speed that it will move across the area would indicate that the
cooler temperatures are valid for the southern Rolling Plains but
how much we will climb for the Caprock remains uncertain. Will
keep upper 80s for Lubbock which will feel downright cold compared
to today.

One more day of slightly below normal temperatures will be in
store for Monday as we keep easterly upslope surface flow in
place across the region. This will likely offset the increasing
heights over the southern U.S. as the ridge starts to
restrengthen. Temperatures will begin to climb on Tuesday into the
upper 90s with 99-102 again by Wednesday. Thursday will be the
hottest day next week with the ridge pretty much at it's
strongest, but then uncertainty starts to creep in by the end of
the week/next weekend. The GFS tries to bring a front into the
Texas Panhandle Saturday while the ECMWF holds off until Sunday.
The ridge will weaken just a tad but remain anchored over the
desert Southwest so it remains to see which model is correct.
Precipitation chances remain uncertain for next week as well as
the extended range models do generate spotty precipitation across
the area but at different times. The GFS favors the overnight
hours while the ECMWF has most of the precip in the morning to
afternoon. Will keep a dry forecast going until we see how things
play out next week.

Jordan

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning until 8 PM CDT this evening for TXZ027-
028-033-034-039-040.

Heat Advisory until 8 PM CDT this evening for TXZ021>024-029-030-
035-036-041-042.

&&

33

Hazardous Weather Outlook...UPDATED
National Weather Service Lubbock TX
1043 AM CDT Sat Jun 17 2017

TXZ021>044-181545-
Parmer-Castro-Swisher-Briscoe-Hall-Childress-Bailey-Lamb-Hale-
Floyd-Motley-Cottle-Cochran-Hockley-Lubbock-Crosby-Dickens-King-
Yoakum-Terry-Lynn-Garza-Kent-Stonewall-
1043 AM CDT Sat Jun 17 2017

This Hazardous Weather Outlook is for the South Plains...Rolling
Plains and the far Southern Texas Panhandle.

.DAY ONE...Today and Tonight

An excessive heat warning is in effect for the western South
Plains from 1 pm to 8 pm this afternoon and evening due to
temperatures reaching 110 degrees or more. A heat advisory is in
effect for the same period across the remaining areas on the
Caprock and the adjacent canyons, for high temperatures of 105 to
109 degrees.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

No hazardous weather is expected at this time.