Area Forecast Discussion
Issued by NWS
FXUS64 KLUB 301754
Area Forecast Discussion
National Weather Service Lubbock TX
1254 PM CDT MON MAY 30 2016
IFR to MVFR cigs have scattered at KLBB and KCDS and will soon at
KPVW. May see a repeat performance at all TAF locations Tuesday
morning but confidence not high enough to include this cycle.
Atmosphere still recovering from last night`s MCS but disturbance
approaching the region from New Mexico will result in scattered
thunderstorm advection/development very late this afternoon and
evening. Some of these storms could affect KLBB and KPVW in the
01Z to 04Z time frame or so. Lower probabilities of thunder will
exist for KCDS, but greater than zero nonetheless. Outside of any
possible thunder issues this evening and low cigs Tuesday morning,
VFR conditions will prevail at all TAF locations.
.PREV DISCUSSION... /issued 629 AM CDT MON MAY 30 2016/
Two areas of low ceilings are encroaching on all terminals at 630
AM - the first is an IFR layer off the Caprock which should envelop
CDS shortly while the second is MVFR about 30W of LBB and PVW and
expanding quickly eastward.
LBB and PVW could fall to IFR for a short while this morning, but
satellite trends suggest MVFR should prevail here. Low ceilings
should erode and restore VFR by midday ahead of TS development
in eastern NM. Will keep TS out of TAFs for now as TS coverage
and duration are just too uncertain this many hours out.
PREV DISCUSSION... /issued 404 AM CDT MON MAY 30 2016/
Large MCS with cloud tops as cold as -76C continued to roll south
into the Hill Country and Edwards Plateau at 3 AM. A large
mesohigh axis extended all the way from the wake of this MCS
northwest to the southwest TX Panhandle with rather low dewpoints
in the lower 50s over much of our CWA. Combined with some stratus
at times, these features are significant enough to warrant a
significant reduction in POPs today as sufficient moisture
recovery and destabilization will face many headwinds. 06Z NAM has
improved markedly over the 00Z iteration with the handling of the
MCS, so if this is correct then there would be a protracted lull
in precip today - much to the joy of outdoor parade attendees. The
one exception to this should occur in our W-SW zones later this
afternoon and evening as upslope storms from NM make strides
northeastward. This activity should be aided by stronger
southwesterlies aloft preceding an upper low in southern CA.
Although marginally severe storms could still emerge within a
narrow corridor of instability along the TX-NM border, feel SPC`s
assessment is solid so we have nixed the earlier severe mention
from the grids.
Ability for surface based storms in our western zones to transition
to elevated modes tonight is not clear at this time. Although low
level moisture improvements will be underway overnight courtesy of a
modest LLJ, isentropic ascent is not much to bite off on. Kept a
broad 30-40 percent storm mention overnight largely for neighboring
office coordination purposes, but later forecasts may need to make
serious revisions to this pending the events of today.
As mentioned above, precipitation chances any given day through
mid-week will depend on what happens on the previous day with
coverage of convection. Models continue to generate precipitation
in the late late afternoon into the overnight hours as we keep
fairly unstable conditions in place aloft ahead of the slow
moving upper-level low that is currently over southern California.
Then there is the issue of the cold front that is still forecast
to arrive late Tuesday into Wednesday morning that will also help
to focus convection. The slow eastward progression of the low will
limit the amount of bulk shear across the forecast area, generally
ranging between 20-30 knots through Thursday which could also be a
factor in how storms develop and organize across the area. Will
keep chance PoPs in the forecast with a window for likely PoPs
Tuesday night into Wednesday morning for the arrival of the front.
Chances for rain should finally start to taper off by Friday as
the upper level low is east of the area and moisture levels
decrease a bit. North to northeasterly flow aloft in both the
ECMWF and GFS should keep any convection in New Mexico while also
helping to keep temperatures from warming up too much and remain
3-5 degrees below normal.