Area Forecast Discussion
Issued by NWS Corpus Christi, TX

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FXUS64 KCRP 160431

Area Forecast Discussion
National Weather Service Corpus Christi TX
1031 PM CST Fri Dec 15 2017


Just a few changes to the forecast late this evening. Adjusted
hourly temperatures and dewpoints a bit to match current trends.
PoPs across the west were adjusted slightly with a decrease in
rain expected for through the early morning hours. Still expecting
rain chances to increase by mid-morning but given how saturated
the boundary layer is now, some patchy drizzle/very light rain is
possible across the southern half of the CWA.

Update for 06Z aviation cycle is below.



Tonight...VFR. Light rain will continue to move in from the
southwest the next couple of hours before drying out later
tonight. Some patchy drizzle is possible but not expecting vsbys
to be impacted. Light and variable winds expected. High

Saturday...MVFR/IFR. Moisture begins to deepen as winds become
more onshore by the late morning. Rain starts up again by late
morning and lasts through much of the day as conditions gradually
worsen with MVFR/IFR cigs developing. Vsbys too may be reduced in
some of the rain. Weak coastal low pressure system is expected to
develop and move along the coast, possibly slightly inland by
late in the afternoon providing moderate to heavy rain at times.
Winds should shift more northerly as the low pressure moves up the
coast. Thunder chances are slightly increasing, though dependent
on the track of the surface low, but we have added a PROB30 group
in for the late afternoon/early evening timeframe at most of our
terminals. Medium to high confidence.


PREVIOUS DISCUSSION... /Issued 344 PM CST Fri Dec 15 2017/

SHORT TERM (Tonight through Saturday Night)...

Upper level low currently over the Gulf of California will eject out
and across Texas tonight and Saturday. Combine this with a coastal
trough expected to develop and a steady stream of Pacific moisture
flowing across the region and get high chances for rain and possibly
a few thunderstorms over the next 36 hours. Light rain that is
currently over the area will continue to dissipate over most of
South Texas...but some light drizzle will could continue into
tonight.  Late tonight, closer to Saturday morning is when we`ll see
the next round of rain begin. Proximity of upper level trough and
positioning of upper jet (right rear quad) will maintain the
potential for isolated thunder for the entire area...however the
best chance for thunder will be along the coast where a weak
boundary could drift inland. Several of the guidance solutions
indicate the surface low moving into the northern coastal bend
during the afternoon hours as a developing surface low track
northward. This also created some difficulties for temp/wind
forecast in coastal areas. More on that in a bit. Upper low and
surface features will move north of the area by Saturday night and
should bring a rapid cutoff to rain chances. Think we`ll be mainly
done by midnight, but lingering some 20/30 pops northeast just due
to questions in timing.

As far as temperatures, cool tonight despite thick cloud cover
continuing. Will see lows in the mid 40s areawide. Highs tomorrow
largely in the 5as, but depending on how that surface feature moves,
could warm into the low to mid 60s along the immediate coast. Have
gone as warm as 64 in the current forecast. If the surface low stays
farther to the east, these locations will be stuck in the 50s.
Expect lows tomorrow night in the 40s once again...lower 40s west
where skies will begin to clear, and mid to upper 40s east.

Marine winds may strengthen once again on Saturday depending on the
strength of the potential surface low/boundary offshore. Small craft
advisory conditions may be reached, but it looks like it would only
be for a few hours Saturday afternoon.

LONG TERM (Sunday through Friday)...

Short wave trough will be moving northeast of the area Sunday as the
weak boundary pushes past the coastal waters. Any rain chances will
be over the coastal waters Sunday with temperatures near normal for
the area. The next southern stream short wave trough will move out
of the southern Rockies into the southern plains of Texas Monday. A
coastal trough will form as the short wave trough approaches on
Monday. This will be a focus for convective development Monday into
Monday night with better chances for rain across eastern areas. The
short wave trough is expected to move east of the area by Tuesday
with drier air moving in by Tuesday night. Warm and dry conditions
are expected for Wednesday into Thurday. Models are consistent with
change in upper level flow pattern by end of the week with an upper
low digging south through the Great Basin by Friday while an
upstream ridge builds north into western Canada. This will lead to a
shallow Arctic air mass building over western Canada that will surge
through the plains Thursday and be moving through the forecast area
early Friday morning. Expect good rain chances with the front on


Corpus Christi    46  60  47  67  58  /  20  70  70  10  20
Victoria          42  58  46  67  57  /  10  80  90  10  20
Laredo            44  50  43  64  53  /  40  80  20  10  10
Alice             45  54  46  67  57  /  20  80  60  10  20
Rockport          46  63  50  65  59  /  10  70  80  10  30
Cotulla           43  51  41  65  53  /  10  80  30  10  10
Kingsville        45  57  47  67  59  /  30  70  60  10  20
Navy Corpus       50  64  51  65  61  /  20  60  70  10  30





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