Area Forecast Discussion
Issued by NWS
FXUS64 KLUB 261149
Area Forecast Discussion
National Weather Service Lubbock TX
649 AM CDT Sun Mar 26 2017
Low level wind shear will persist for a few more hours as a strong
low level jet has set up overhead. Surface winds will quickly
increase this morning out of the west as a strong low pressure
system skirts to the north of the region. A cold front moving
through this evening will shift westerly winds to the north.
.PREV DISCUSSION... /issued 427 AM CDT Sun Mar 26 2017/
Windless days are short lived around here this time of year and
Saturday was no exception. Strong winds will return today. A dryline
will race east today along with a surface low moving across the
Texas Panhandle. Strong westerlies at the surface and aloft will
spread over the region today. This is in response to a compact but
strong short wave trough moving along the 37th parallel. Very deep
mixing will occur today under the strong westerly flow aloft.
Forecast mixing values are between 650-600mb. Winds at this level
show a broad area of 35-40kt with a slightly stronger max moving
across this afternoon. Given the deep mixing, MOS winds look to be
too low and a critical fire weather threat is likely for today. A
cold front will move into the area during the overnight hours
keeping winds breezy for areas off the caprock.
Quiet conditions will dominate Monday with a flat upper level
ridge passing east during the day, thin high clouds spilling over.
And not all that much warmer than normal along with light
southeast breezes, though ramping up a bit late in the day.
A large upper level low pressure system is still expected to cross
the southern plateau and Rockies Tuesday with height falls and
modest moisture surging north and northwest into the area.
Solutions for Tuesday disagree yet on how much moisture and how
far west it will spread with the WRF/NAM flow remaining backed a
bit longer than the GFS, which is quicker and more to the north on
its track. WRF/NAM and ECMWF are mostly in agreement and we have
trended still a bit towards these solutions. Instability will
increase and pool along a surface trough/dryline over the central
or western South Plains - and potentially still as far west as the
New Mexico border - giving opportunity yet for thunderstorm
development as lapse rates steepen late in the day. Although the
level of thunderstorm discreteness is unknown given uncertain
moisture levels, the combination of shear and instability give
rise for hail, high wind, and even a tornado threat. Precipitable
water levels also will improve to at least an inch over the
Rolling Plains late in the day, but differ widely yet between
under a half inch to over an inch over the high plains.
On Wednesday, solutions trends are a bit more consistent with the
upper low crossing the northern part of our area with notable
drying overtaking most of the region. Although our confidence in
this track aren`t super high, the previous trends downward in
precipitation chances and amounts appear appropriate. A cold
front passage late Wednesday would help cool and moisten lower
levels across our northern zones, and may help initiate light
precipitation mainly over this area within the backside of the
upper low. System eventually will scoot off to the east Thursday
- we favor a more progressive flow - as the next upper trough
already will be sharply digging through the western Great Basin.
So, drier and milder Thursday and probably Friday. A very large
spread currently has moved into the solutions for next weekend,
giving rise to lower overall confidence in precipitation outlook.
Our input therefore was to lessen chances a bit until confidence
Critical fire weather conditions can be expected today as an upper
level storm system moves north of the region. Strong winds will
spread over the area from the west with strongest winds across the
western South Plains lessening to the east. Temperatures will warm
to 10 to 15 degrees above seasonal averages today. Very dry air
moving into the area as well will cause afternoon relative humidity
values to be around 10 percent across the South Plains and Rolling
Plains. Slightly higher relative humidity values are expected over
the extreme southern Texas Panhandle. Therefore, red flag conditions
are anticipated over the entire South Plains and adjacent areas off
the caprock. Farther off the caprock to the east, the three hour
criteria for winds looks like it will fall short.
There also could be a threat for at least elevated fire weather
again Tuesday near the New Mexico border. Confidence in this
is low at this point with large conflicts in how veered or backed
the low level flow will remain late on Tuesday. RMcQueen
Red Flag Warning from 1 PM this afternoon to 8 PM CDT this
evening for TXZ027>031-033>037-039>043.