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Area forecast discussion 
National Weather Service Lubbock Texas
346 PM CDT Wednesday may 6 2015

Short term...
convection struggling to initiate locally this afternoon as somewhat
expected given the lack of forcing for ascent. As of 315 PM...a
diffuse dryline was positioned roughly from Turkey to Crosbyton to
Post with a flat cumulus field along and to its east. Temperatures
in the middle 80s and dewpoints in the upper 50s to lower 60s have led
to cape values in the 2-2.5 kj/kg range...but will have to monitor
the development of any surface convergence for any deep updrafts to
develop. If anything can develop it will likely be across the
rolling plains and have on the order of 30-40 knots of deep layer
shear to work with...suitable for a few rotating updrafts and
supercell structures. The primary threat will be large hail to
baseball size...isolated tornadoes...and heavy rainfall. Damaging
wind gusts could also develop as downdrafts become dominant later
this evening.

An upper low digging south across the Great Basin will bring a
period of height falls later tonight into Thursday
morning...potentially leading to isolated to scattered storms across
much of the South Plains through the rolling plains as the dryline
retreats and dewpoints surge into the upper 50s/60s areawide. A 30-
40 knot low level jet will also be in place at this time...enhancing
storm relative inflow. Plenty of instability should also be on tap
with very moist low-middle levels.

Overnight and Thursday morning activity which develops will have a
profound impact on initiation Thursday afternoon as diffluent
southwest flow aloft moves overhead. Tough to pinpoint any shortwave
impulses at this time...but a ripe atmosphere ahead of an eastward
mixing dryline will not take much to be perturbed. Prognosticated convective available potential energy of
2-3 kj/kg and 0-6 km bulk shear of 40-45 knots will exist east of
the dryline...promoting supercells capable of producing large
hail...damaging downburst winds...and isolated tornadoes. The latter
threat may be enhanced along residual outflow boundaries from early
day activity.

Long term...
focus continues to be on good thunderstorm chances Friday
and Saturday as the next upper low moves from southern calif early
Friday to Colorado late Saturday. Timing short waves ejecting
from the low remains problematic...but overall pattern will
remain one of backed low level flow drawing moisture back into the
region while the dryline shifts eastward across the South Plains. This
pattern should generate at least scattered storms while any
additional middle to upper support could help increase coverage
beyond that. Central to eastern areas continue to look preferred.

A cold front moving through the forecast area Sunday in the wake of
the upper low followed by short wave ridging will promote fair
weather Sunday and Monday /with possible exception of an isolated
storm far southeastern zones with the frontal passage Sunday/ with cooler temperatures.
Once the ridge axis shifts eastward toward Tuesday or Wednesday and low
level moisture returns on southeast low level flow...will see rain
chances return to the forecast area.


Preliminary point temps/pops...
Friona 51 79 50 79 / 10 10 20 10
Tulia 57 78 54 79 / 20 30 20 30
Plainview 57 78 55 79 / 20 30 30 30
Levelland 58 82 56 81 / 20 20 30 20
Lubbock 61 81 58 82 / 30 30 30 30
Denver City 59 82 54 82 / 20 20 30 20
Brownfield 59 84 57 84 / 30 20 30 30
Childress 63 80 61 82 / 40 40 40 60
spur 62 80 59 81 / 30 40 40 50
Aspermont 64 82 63 84 / 50 40 40 60


Lub watches/warnings/advisories...



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