Area Forecast Discussion
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FXUS64 KLUB 191132

Area Forecast Discussion
National Weather Service Lubbock TX
632 AM CDT Fri May 19 2017

Dense fog at CDS continues as the sun rises this morning, though
it is expected to erode in the hour or two. A chance of
thunderstorms exists this afternoon, mainly for CDS, though timing
and coverage will be better known once morning convection to the
south moves out.


.PREV DISCUSSION... /issued 306 AM CDT Fri May 19 2017/

It`s a complicated forecast today as the strong, but slowly-
moving, storm system that has crawled across the western CONUS the
last couple of days is spinning over the Colorado Rockies early
this morning. The upper low will move out over the High Plains of
eastern Colorado this afternoon and over western Kansas this
evening. At the surface a cold is moving southward through the
northern Texas Panhandle, well ahead of schedule. Meanwhile a
surface low is developing south of Lubbock with light winds across
the forecast area early this morning. Flow around this low will
keep rich low level moisture in place across the Rolling Plains
but dry air across the western counties.

Convection is already underway to our south along a retreating
dryline that is likely being helped with mid level cooling aloft
from the approaching upper low. The hi-res models, the HRRR doing
a particularly good job, have been showing this early morning
development across the Permian Basin for the last few hours. This
convection aligned WSW-ENE will move generally northeastward
through the morning, clipping the southeast corner of the forecast
area. Additional convective initiation is possible later this
morning as the cold front moves into the richer moisture of the
southeast Panhandle, although the hi-res models are less bullish
with this idea. It is possible that the morning convection to our
south and southeast will cut off the supply of moisture later
today, and this may be what is coming into play with the models.
The cold front is likely to stall some across the northern part of
the forecast area later this morning as it moves into a warm and
well-mixed air mass with the slow-moving surface low to the south
and southeast of Lubbock possibly holding it up as well. A better
surge to the front will occur mid to late afternoon giving another
window for thunder off the Caprock. In general, it appears the
better chances for precip through the day will be just to the east
and southeast of the forecast area, and we will run with chance
PoPs at this time for both the daytime and evening periods. It
should be mentioned that the moisture across the far eastern part
of the forecast area combined with a decent shear profile will
lead to a risk for severe weather, mainly hail, even as early as
this morning.

The other difficult issue with the forecast for today is
temperatures. There should be a pretty stark gradient across the
forecast area with high temperatures likely close to 20 degrees
different from the cool northwest to the warm southeast.

Much cooler air will filter in behind the front tonight with
temperatures expected to be below normal Saturday afternoon. South
winds will help warm temps a bit exiting the weekend, but no
significant increase in progged thicknesses suggest a modest
warmup toward seasonal average is in store.

The next precip maker will be a short wave trough moving
southeastward on the backside of a building West Coast upper
ridge. Models have been consistent in bringing a period of more
widespread precipitation to the area Monday into Monday night.




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