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FXUS64 KLUB 231754
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
1254 PM CDT Thu Mar 23 2017

.AVIATION...
Strong winds will be the main aviation concern for the next 24
hours and through the remainder of the day Friday. In addition,
there is a slight chance of TSRA at any of the terminals this
evening. We have included a PROB30 group at KCDS where the chances
are slightly better. Wind gusts of 50 kts or more are possible in
the vicinity of any TSRA. Winds will decrease slightly this
evening but then increase again during the day Friday. Finally,
blowing dust may bring sporadic VSBY reductions at KLBB and KPVW
through about 00 UTC.

&&

.PREV DISCUSSION... /issued 1133 AM CDT Thu Mar 23 2017/

UPDATE...
The latest guidance this morning does not support much change to the
overall forecast picture for this afternoon and evening. We`ve
made only some minor adjustments at this point, slightly
increasing PoPs across the southern Panhandle, centered roughly
around Swisher County, which seems to be the focus in the high-res
models and the ensemble means. And we`ve reduced PoPs along the
TX-NM state line, as the latest guidance suggest the dryline makes
slightly more eastward progress than previously indicated.
Satellite imagery shows lift spreading into western NM this
morning. The strongest upper-level divergence and lift is still
expected to overspread northeast NM and the western TX Panhandle,
decreasing farther south, which leads us (and much of the
guidance) to trend toward more isolated activity across the srn
half of the forecast area. As for the timing, it still looks like
development around 5-6 pm CDT along the dryline, with the window
for storm impacting Lubbock around 7-9 pm. Finally, the primary
hazards with these storms are still expected to be damaging wind
gusts to around 70 mph and large hail up to around 1.5 inch
diameter. The tornado threat should be very low, with relatively
high LCLs along the dryline, although as previously mentioned,
there could be a window for a tornado centered around 7pm and
little farther east where any established storm may tap into
slightly better moisture and increasing/backing winds before the
boundary layer cools.

PREV DISCUSSION... /issued 452 AM CDT Thu Mar 23 2017/

SHORT TERM...

An active weather day is shaping up across the region with strong
winds this afternoon, and then potential severe thunderstorms late
this afternoon and evening.

A vigorous upper level storm system near Las Vegas, Nevada early
this morning will cross the Four-Corners later today, en route to
southeast Colorado early Friday morning. System appears it will
deepen slightly between 06z and 12z Friday. Surface pressure falls
already underway across the southern plains will increase later
today, with stiff southerly flow developing, enough to justify wind
advisory conditions across the area this afternoon and at least
early evening.

A surface dry-line will tighten near the Texas-New Mexico border;
solutions generally agree within a county-width or so where the dry-
line will shape up late this afternoon, though we have continued to
favor the more western versions with the surface low still to our
west as well. Thunderstorm chances will improve from late afternoon
into the evening as height falls lead to steepening mid level lapse
rates and weakening of the low level cap. Coverage of thunderstorms
still not clear due to relatively poor overall moisture depth and
quality from source regions further south and east in the lone star
state. But still should be adequate for isolated to scattered
coverage initially late this afternoon, and perhaps still with
enough low level hodograph turning to support discrete supercells
and at least a small tornado risk for the western South Plains and
southwest Panhandle.

Thereafter, nearly straight line hodographs favor a potential squall
line as a Pacific cold front catches up and sweeps the line eastward
this evening through the central and eastern South Plains; high
winds and large hail will become the primary threats. Thunderstorm
chances will dwindle on the Caprock later tonight but will continue
over the Rolling Plains at least a little after midnight before
veering leads to drying there as well. Most other guidance followed
fairly close. RMcQueen

LONG TERM...

By the start of this forecast period, models are in overall
excellent agreement of the position of the upper level low, placing
the center just north of the TX and OK Panhandles. From there, the
turn to the southeast is still slated with the GFS pulling the
system away ever so slightly faster. In the grand scheme, not much
has changed with this forecast package as far as winds go. H7 winds
of 50 to 60 KT with a narrow band of 75 and 850mb at 45-50 KT will
mix down to produce healthy wind speeds/gusts at the surface
during the day and evening Friday. Therefore, have issued a High
Wind Watch for the top two rows of counties of the forecast area
beginning 11 AM Friday morning and extending through 7 PM. These
counties should receive enough wrap around moisture and cooling
from the exiting system to keep fire weather concerns lower,
however, our bottom two rows of counties will be of greater
concern. Winds of 25-35 with gusts to 50 and RH values falling
into the teens are cause for some concern with the cured fuels.
Therefore, a Fire Weather Watch has been issued for those counties
beginning at 11 AM Friday and extending until 7 PM. Should
conditions still look unfavorable or worsen, this could be
upgraded to a Red Flag Warning. Blowing dust will also be a
problem, especially on the Caprock, Friday, causing possible
reductions in visibilities. So, to recap the Friday hazards:
secure items that could blow away, be aware that some tree limbs
are likely to break in winds like these, avoid all outdoor
burning, understand that driving (especially in high profile
vehicles) may become difficult at times, and visibilities could
drop quickly due to blowing dust.

Saturday will be a downright beautiful day compared to the previous
two with light winds, highs in the 70s and mostly sunny skies.
Sunday ushers the passage of a weak trough north of the region that
does little more than bring us a breezy afternoon. From there we are
watching the next bowling ball low develop for mid week. At this
point, there is still too much model disagreement on the timing and
track of this system to put much confidence in high POPs attm. The
Euro is very progressive with this system, while the GFS takes its
time developing a deeper low further into the Desert Southwest.
Other solutions lie in between. Therefore, have kept to slight
chance / low end chance POPs until greater model consensus begins to
develop.

FIRE WEATHER DISCUSSION...

(Today) Strong south winds will develop this afternoon and will lead to
critical fire weather conditions west of the dry-line. There is
potential the dryline will be just far enough east for elevated to
critical fire weather to develop along the state line. We will
continue assessing the need for either Red Flag Warning or Elevated
Fire Danger products through the morning. RMcqueen

(Friday) In response to a passing and exiting potent low pressure
system to our northeast, winds are expected to pick up across the
southern half of the South and Rolling Plains to between 25 - 35
mph with gusts to 50. Though temperatures will be cooler with the
passage of a Pacific front, RH values are still forecast to drop
at or below 20 percent for this area. Much of the area will be
closer to 15 percent. Therefore, a Fire Weather Watch has been
issued for all of the southern half of the South and Rolling
Plains on Friday from 11 AM to 7 PM. Further to the north, though
winds will be higher, some moisture is expected to return to the
area on the backside of the low, keeping RH values above 20
percent. A Rangeland Fire Danger Statement may be needed for those
areas, though, due to sustained elevated 20 foot winds of greater
than 25 mph.

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Friday morning through Friday evening
for TXZ033>044.

Wind Advisory until 9 PM CDT this evening for TXZ021>044.

Red Flag Warning until 9 PM CDT this evening for TXZ021-022-027-
028-033-039.

High Wind Watch from Friday morning through Friday evening for
TXZ021>032.

&&

$$

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