Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 170050 CCA
AFDSJT

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE SAN ANGELO TX
0749 PM CDT WED APR 16 2014

.AVIATION...
/00Z TAFS/

The main aviation concerns will be MVFR stratus and low-level
wind shear. Model guidance indicate MVFR conditions developing at all
terminals after 07z, lowering to IFR conditions after 10z.
Confidence in IFR conditions developing was low, so we opted to
maintain lower-end MVFR conditions, and await further guidance.
Low-level wind shear was inserted for KABI and KSJT.

Doll

&&

.PREV DISCUSSION... /ISSUED 352 PM CDT WED APR 16 2014/

SHORT TERM...
(Tonight and Thursday)

Breezy and warm conditions continue this afternoon across the
area. A cold front is moving south through the Texas panhandle and
western Caprock areas of west Texas. We can expect to see the
breezy conditions persist through the overnight hours as a LLJ of
30 to 40 knots develops across west central Texas. With increasing
moisture, breezy winds overnight, and low clouds developing late,
expect warm overnight temperatures only dropping into the low to
mid 50s.

On Thursday, the cold front will move into our forecast area,
turning winds to the east/northeast by the end of the day. The
front will turn winds to the northeast for the western half of the
area first, allowing moisture to continue to advect northward for
eastern areas. As was mentioned in the previous AFD, the
atmosphere is expected to be capped preventing deep convection on
Thursday. However, saturated lower levels with the help of the
front may result in a few showers for locations generally east of
a Sweetwater to Junction line. Highs tomorrow will be similar for
the most part, but may be a few degrees cooler for eastern areas
where clouds will limit heating.

20

LONG TERM...
(Thursday night through Wednesday)

Weak isentropic ascent will be in place across West Central TX on
Thursday night over the top of a very shallow "cool" airmass. The
environment will be strongly capped, but there should be enough
moisture/ascent to produce a few showers across the area. I did
include a slight chance of showers during the overnight period. The
timing appears to be coincident with shortwave ridging aloft,
however, so I don`t anticipate much in the way of appreciable
rainfall amounts. On Friday, the ridge axis will shift east as a
potent shortwave trough moves into the southwest CONUS. A fast
moving wave downstream of the trough axis will lift northeast across
the area Friday and Friday night. The models are hinting at some
very light precipitation across the area ahead of this wave on
Friday but I think the primary impact will be mostly cloudy skies.
We`ll continue to monitor the potential for light rain and/or
drizzle, especially early in the day.

A stronger shortwave is progged to move northeast across West TX on
Saturday. Southerly flow will continue to pump Gulf moisture into
the region. Increasing large scale ascent and mesoscale lift
attendant to the left exit region of the subtropical jet will yield
scattered showers and thunderstorms, with the best chance during the
afternoon and evening hours. While instability and shear parameters
certainly do not scream severe weather, it is mid April, so we`ll
have to keep that door open. If any storms do become severe, it will
likely be the exception, rather than the rule. Temperatures are
still expected to warm into the mid 70s despite the overcast skies
and precip chances.

The upper trough axis will take its time moving across the area, so
showers and thunderstorms will remain in the forecast areawide on
Sunday. I think convection will be more spotty later in the weekend
with the cap expected to be a bit stronger. That said, convective
parameters suggest a greater potential for severe weather for Sunday
afternoon and evening. Forecast temps in the low to mid 80s push
SBCAPE values north of 2000 J/kg with 0-6km bulk shear in the range
of 30-40 kts. Similar temperatures are expected on Monday but precip
chances will shift to the southeast portion of the CWA in the
vicinity of a weak surface boundary.

Generally dry weather is expected Tuesday and Wednesday as ridging
overspreads the area on the backside of the departing trough. We
will retain our low-level moisture through the period which will
help keep overnight low temperatures in the mid 50s to lower 60s
with afternoon temperatures warming to near 90 degrees.

Johnson

FIRE WEATHER...
Will leave the Red Flag warning going through the evening hours.
Area observations within the RFW area remain in or near critical
fire weather conditions, and conditions will likely continue to be
at or near critical through the next few hours.

Fire weather conditions will improve tomorrow through the weekend
with strong moisture advection into the area beginning Thursday, and
a chance for showers and thunderstorms over the weekend.

Temperatures warm back into the 80s and 90s next week which will
result in increasing fire weather concerns.

20

&&

.PRELIMINARY POINT TEMPS/POPS...
Abilene  73  52  70  53  75 /   0   0  20  20  10
San Angelo  76  53  76  55  77 /   0   0  10  10  10
Junction  73  54  72  55  77 /   0   5  10  20  10

$$

Doll







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