Area Forecast Discussion
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FXUS64 KLUB 221723 AAA

Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
1223 PM CDT Mon May 22 2017

Biggest uncertainty today revolves around possibility of
thunderstorms at all three TAF sites. Confidence on timing and
location is very low and uncertainty high as there are multiple
differences between computer models. If there is an overall
consensus, it is for storms to be closest to KLBB and KPVW after
21 UTC this afternoon. Complicating factors is a cold front that
will move towards the area overnight tonight into Tuesday morning.
Additional storms may form along the front but coverage also is
highly uncertain. Will have to leave any mention of TSRA out of
the TAFs and expect amendments through the afternoon as the
forecast becomes more clear.

VFR conditions in place at KLBB and KCDS with MVFR ceilings at
KPVW. Expect ceilings to bounce between VFR and MVFR through the
day before going back to MVFR and possibly IFR tonight. Cold
frontal passage is expected before sunrise Tuesday and will have
to see if IFR ceilings will remain behind the front.



.PREV DISCUSSION... /issued 1207 PM CDT Mon May 22 2017/

Updated to push back the greatest precip chances to later this
afternoon and evening, favoring our W-SW zones initially and then
expanding SE. Also raised max temps a few degrees in areas where
stratus has temporarily disappeared.

Visible satellite at 1130 AM captured an axis of boundary layer
Cu development already underway in NM from Las Vegas south to
Cloudcroft coincident with a Theta-E ridge. Further insolation
will serve to erode MLCINH in these areas and lead to storm
initiation in a few hours, particularly as an upper trough axis
tracks SE. A secondary area of storm development may emerge near
Clovis along a well-defined W-E boundary/surface trough evident
on satellite and also regional METARs and mesonets. Provided low
clouds continue to erode across our western zones, MLCAPE of
nearly 1000 J/kg and low WBZ heights will favor hail initially,
then more wind with time as convective outflows consolidate and
breed linear forcing. Ample forcing with PWATs around 1" should
also lead to heavy downpours and minor flooding in locales.

PREV DISCUSSION... /issued 251 AM CDT Mon May 22 2017/


RAP and IR satellite analysis showed a large upper level low
pressure center spinning over the US/Canadian border along the
Minnesota state line this morning. This low is large enough
currently to be dominating much of the flow in the CONUS minus the
extreme western CONUS where a ridge of high pressure is beginning to
build. Smaller shortwave disturbances are rotating in the flow
around this low creating areas of thunderstorms and heavy rain, such
as that seen in Laredo, TX today.

One such shortwave is set to traverse eastern NM into West Texas
later today, firing off a round of convection. Steering flow should
be sufficient to move storms eastward keeping any training storms
(i.e. flooding threats) to a minimum. However, there is the chance
that some storms this afternoon and evening will become severe. The
environmental setup from RAP analysis for this afternoon looks like
this: CAPE 1500-2000 J/kg, bulk shear at least 40 kt, mid-level
lapse rates ~8 degrees, dewpoints in the mid to upper 50s...all
great ingredients for big storms. One caveat today will be the cloud
cover. Should we see too much cloud cover, diurnal heating will be
quashed. One other caveat, models are showing a jet max crossing
just slightly to our south across the Permian Basin late this
afternoon and evening. All said, though, believe with the amount of
moisture and available energy, the potential still exists for a few
severe storms with large hail and damaging downburst winds. The
event won`t be done with just one round, though. A cold front will
be driving southward overnight, and storms are expected to fire
ahead of this feature. Models are even agreeing on post-frontal
shower activity through at least noon on Tuesday. By Tuesday
evening, though, the front will have driven out the last of the
moisture, and we will enter a dry spell that looks to last into the
weekend. Ridging builds in for Thursday making for an extremely
rapid warm-up into the upper 90s for much of the forecast area. In
fact, a few models are hinting at the triple digit mark for that
day, which would make for nearly a 20 degree heat-up in 24 hours.
Slightly more zonal flow returns for Friday, but that does little to
relieve the heat. As a trough approaches on Saturday, somewhat more
seasonable temperatures return, but we certainly have been spoiled
by the cool weather...and summer is not far away.




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