Area Forecast Discussion
Issued by NWS Midland/Odessa, TX

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FXUS64 KMAF 171126
AFDMAF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX
626 AM CDT Fri Apr 17 2015

.DISCUSSION...

Please see the 12Z aviation discussion below.

&&

.AVIATION...

VFR conditions will prevail through the forecast period, with
southerly winds gradually shifting to the west/northwest as a weak
front moves through the area this morning. A few thunderstorms
are possible this afternoon and early this evening which could
impact KMAF or KFST, though given the best chance of storms is
east of the terminals, have not included mention in the TAFs at
this time.

&&

.PREV DISCUSSION... /ISSUED 445 AM CDT Fri Apr 17 2015/

DISCUSSION...

A pre-frontal trough ahead of an advancing Pacific front interacted
with the retreating dryline overnight to generate a line of storms
across southeastern New Mexico and northwestern Permian Basin.
These storms have moved northeast into the Texas Panhandle and have
largely remained sub-severe. Currently, a few showers continue to
percolate northeastward across the southeast New Mexico plains,
and a remnant outflow boundary from the aforementioned overnight
convection is moving southeast through the central Permian Basin,
though is not expected to generate additional convection through
the early morning hours.

The main focus today will be the continued threat of severe storms
as the Pacific front continues to move east, allowing for additional
convergence along the dryline that has been responsible for
generating strong to severe storms across the area the past couple
of days. As dry air is ushered into the area via westerlies behind
the front today, the dryline will be pushed east, and thus it looks
like the area with the best chance for severe storms today will be
across the eastern Permian Basin and Lower Trans Pecos. In this
area, southeasterly winds ahead of the dryline will continue to
advect moisture into the region, and with highs expected to climb
into the 70s and 80s once again this afternoon, diurnal
destabilization is expected to result in MLCAPE values from 1000 to
2000 J/kg along and ahead of the dryline. High resolution model
guidance indicates that convective initiation will occur by mid to
late afternoon across the eastern Permian Basin and Lower Trans
Pecos, with storms expected to intensify as they move east into a
more favorable environment in the warm sector coincident with a
vort max that is progged to eject out ahead of the low pressure
system currently over the Four Corners region. The Storm
Prediction Center has highlighted the aforementioned area along
and ahead of the dryline in the eastern Permian Basin and Lower
Trans Pecos in a Marginal Risk area for severe weather, with large
hail and damaging winds being the primary threats. Storms will
spread eastward tonight, and as dry air continues to advect into
the region from the west, the dryline will also shift east,
resulting in diminishing chances for storms tonight, with only a
slight chance of storms lingering on Saturday across the Lower
Trans Pecos.

The closed low currently over the Four Corners will open up as it
slowly lifts northeast into the plains and rejoins the northern
stream flow over the next 24 to 48 hours, with storm chances ending
from west to east by late Saturday as the trough axis swings through
the area. A return to quasizonal flow aloft will occur by Sunday,
with a weak surface front edging southward into the area Sunday
night marking slightly cooler temperatures for Monday.  The dry
period will be rather short lived, however, as by Monday night,
southeasterly surface flow will once again set in across the area,
allowing for increased moisture return from the Gulf.  By Wednesday,
models indicate the dryline forming across the area once again, but
given uncertainties as to the exact location, have maintained the
slight chance to low chance pops across the eastern half of the
forecast area for Wednesday and Thursday.  Yet another closed low
looks to take shape and dive south toward Baja by late in the
extended, with quasizonal flow aloft transitioning to southwest flow
by late Thursday into Friday. However, models diverge in the
handling of this feature heading into next weekend, and thus have
not deviated from the blended guidance at this time.

FIRE WEATHER...

An upper level low over the Rocky Mountains will spread very dry air
east into the central Permian Basin today. In fact, relative
humidities this morning are already below 15 percent in the
Guadalupe Mountains and parts of Eddy County. However the upper low
is still a good distance from the area so winds in southeastern New
Mexico and west Texas will generally remain below 20 mph. The
exception will be in the higher elevations of the Guadalupe
Mountains where stronger mid level winds will be able to mix down
with the help of afternoon heating and it is this area where a Red
Flag Warning has been issued. The upper low is moving very slowly
east so similar conditions are expected to develop tomorrow with
very dry air over much of the area but winds struggling to reach 20
mph. High pressure moving into the area Sunday will bring in enough
moisture to reduce the critical fire weather threat into early next
week.

&&

.MAF WATCHES/WARNINGS/ADVISORIES...
NM...RED FLAG WARNING from Noon today to 9 PM MDT this evening FOR
     THE FOLLOWING ZONES... Guadalupe Mountains NP/Lincoln
     NF/LNZ.

TX...RED FLAG WARNING from Noon today to 9 PM MDT this evening FOR
     THE FOLLOWING ZONES... Guadalupe Mountains.


&&

$$

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