Area Forecast Discussion
Issued by NWS
FXUS64 KLUB 181733 AAB
Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
1233 PM CDT WED MAY 18 2016
KLBB and KPVW continue to bounce between MVFR to IFR and expect
this to continue through the next 24 hours. KCDS may manage to go
VFR for brief periods of time but expect prevailing conditions to
be MVFR to IFR...especially after midnight local time. Periods of
rain and drizzle will continue at all three terminals through
tonight. Expect a lull in precipitation later this evening before
another round of prevailing precipitation starts up in the early
morning hours Thursday through much of the morning. Confidence in
the timing and conditions is a bit better this afternoon but still
expect some amendments through the day as conditions unfold.
.PREV DISCUSSION... /issued 652 AM CDT WED MAY 18 2016/
Low ceilings should persist at all terminals for the next 24
hours. We expect flight categories to be mainly IFR to MVFR, but
KCDS may see a period of VFR this afternoon. Tonight, ceilings are
expected to lower again into IFR range and possibly LIFR. Also,
-SHRA is expected through the day, with a lower chance of -TSRA in
the vicinity of any of the terminals this afternoon and evening.
Surface winds will be mainly from the Northeast to East, and will
go light and variable tonight.
PREV DISCUSSION... /issued 403 AM CDT WED MAY 18 2016/
At 3 AM, a broad area of rain showers was exiting the Rolling Plains
while isolated showers continued across the western and southern
South Plains. Satellite imagery showed that the main upper low was
still quite a ways off to the west near the srn CA/srn AZ border,
with several weak impulses extending downstream across NM and into
northwest Texas. The latest indications are that upper-level lift
will be muted this morning, with isentropic upglide of the near-
saturated airmass the main mechanism for shower activity. At the
surface, a surface ridge will remain wedged against the higher
terrain of NM and southwest TX keeping us in cool upslope flow. In
this regime, overcast skies will continue with scattered, mainly
light rain showers through about mid-day. High temps will only reach
the 50s, and some low 60s east.
As this upper-low swings into New Mexico this afternoon, upper-level
divergence and lift is expected to increase across eastern New
Mexico and West Texas. This should resulting an expanding area of
precip. across southwest Texas into the Permian Basin, which should
then progress north and east across much of our forecast area. There
is still some lingering uncertainty regarding the specifics, as in
the precise timing and how far to the north and east the shower
activity will track. Then later this evening, there are some
indications that the best rain chances will shift into the southern
Rolling Plains, where the upper-lift intercepts the lifting front.
All in all it appears that rainfall totals should be highest across
our southern counties, and lowest in the north or northeast.
Instability will be very limited with nearly moist-adiabatic lapse
rates over the low-lvl inversion. But the increasing large-scale
ascent should be able to produce some embedded t-storms with heavier
rainfall rates. Some locally heavy rainfall will be possible, but we
do not anticipated any larger-scale flooding concerns at this
The long term may see a return to an active dryline pattern this
weekend with warmer temperatures.
The upper level system currently affecting the area will have its
trough axis finally pass over the area on Thursday. This will end
precipitation and cooler temperatures on Friday. Short wave
ridging will quickly build overhead on Friday with a dryline
already developing. There is a low chance of convection initiating
along the dryline boundary on Friday afternoon with a building
ridge overhead. Furthermore, mid levels will be drying out
following the trough passage.
Upper level winds will quickly back in advance of the next trough
entering the western CONUS. Models have been advertising an active
dryline under this regime and this pattern is a typical
representation of a May dryline for West Texas. This deep trough
will allow copious amounts of low level moisture to stream into
the region and with the trough staying as far west as it is will
allow a dryline to retreat well west of the area. Best chances for
convective activity look to be on Saturday and Sunday evenings.
Additionally, analog guidance does depict several severe events
across West Texas for this weekend. Models now show stronger
westerly flow for early next week shoving the dryline to a more
easterly location. Although exact location will be determined
later, the dryline will continue to remain active through this
period early next week but greatest precipitation chances will
exist off the caprock and points farther east.