Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/26/18
Area Forecast Discussion
National Weather Service Lake Charles LA
1000 PM CST Tue Dec 25 2018
Wx map shows sfc high pressure over the East Coast, and low
pressure beginning to intensify over AR/W TX this evening. Over
our region, light southeast winds 5 mph or less to calm noted,
with patchy fog reported at a few locations across C LA. For the
forecast update, minor changes to show patchy to areas of fog
after midnight through 6 am, mainly due to lowering ceilings. May
at times become dense, but the confidence in the widespread dense
fog to occur is less for this forecast than it was this morning.
Reason being, various guidance is conflicting in the signal, HRRR
showing no fog, with NAM12 showing pockets of dense fog at various
times overnight. By daybreak, the winds will likely pick up in
response to a tightening pressure gradient, mixing out any fog
that would have developed by 9 AM. Other than adding marine
hazards for Wednesday & Thursday winds/seas, remainder of the
forecast remains unchanged.
Patchy to areas of fog will be possible this evening and
overnight, but not expected to become widespread like this
morning due to the expected increase in the pressure gradient and
winds. Expecting the winds to increase near 20 knots or greater
in 12 hours, and 25-30 knots by Wednesday evening/early Thursday
morning. Due to this, raised Small Craft Advisories for the
0-60nm Coastal Waters from Intracoastal City to High Island
beginning at 16z (10 AM CST) Wednesday, and all the 0-60nm zones
and inland lakes/bays beginning at 00z (6 PM) Wednesday.
.PREV DISCUSSION... /issued 520 PM CST Tue Dec 25 2018/
AVIATION...Lower ceilings and visibilities will redevelop
tonight and linger into Wednesday morning. Winds will increase
earlier in the day tomorrow likely ending the reduction is vis
earlier than this past morning. Winds will be southeast through
PREV DISCUSSION... /issued 501 PM CST Tue Dec 25 2018/
An unseasonably warm Christmas Day across the region despite
ample cloud cover, with readings rising to around 70 in spots
where the sun was able to peek through this afternoon. A cloudy
but otherwise quiet night is expected, with the potential once
again for fog development to occur. Probs not quite as high as
they were last night, but still indicate possible advection fog
beginning over the nearshore coastal waters this evening and
subsequently spreading inland after midnight. For now will simply
insert patchy fog wording and let subsequent shifts evaluate the
need for any possible advisory.
Robust upper trof currently over the Desert SW progged to
continue EWD tonight and WED, with the pressure gradient
tightening over the area between its attendant SFC low and high
pressure over the Mid-Atlantic. Winds will near advisory criteria
over the coastal counties and parishes by the afternoon.
Increasing lift associated with a lead shortwave ejecting ahead of
the main upper trof will result in an initial round of showers and
thunderstorms spreading into the area tomorrow afternoon and
evening, with a more robust and organized band of convection
developing farther west into TX along/ahead of the SFC front.
This more organized band of convection will begin to push into E
TX after midnight, bringing an attendant risk of locally heavy
rainfall and SVR TSTMS. Progged kinematic fields are quite
impressive, with 0-1KM shear/helicity of 40-50 KT/400-500 m2/s2.
Questions continue to surround degree of instability and the
possible presence of a near SFC marine/stable layer limiting more
discrete development ahead of the primary band. Nonetheless, a
risk of hail/damaging winds along with embedded QLCS tornadoes
will exist with the linear convection as it pushes through the
area from late tomorrow night through the day on Thursday.
Areawide rainfall totals of 1 to 3 inches are expected, with
locally higher amounts possible. Have continued with the locally
heavy rainfall wording for this period.
Brief reprieve in rain is expected on FRI, but the SFC front is
progged to stall over the NW Gulf, with one or more impulses
ejecting through SW flow aloft brining about periodic rain chances
for the weekend into early next week.
Patchy fog is possible tonight as southeast flow continues to
result in Gulf moisture streaming atop relatively cooler shelf
waters. Southeast winds will increase and become gusty by
tomorrow afternoon as an upper level storm system and associated
surface low enters the western Plains. A small craft advisory will
likely be needed. Winds gusts in excess of Gale force are
possible by tomorrow night. The strengthening onshore flow will
result in above normal tidal readings, with latest guidance
indicating a coastal flood advisory may be needed for minor
coastal flooding tomorrow night. Widespread showers and
thunderstorms are expected Wednesday afternoon through Thursday
night as this storm system lifts northeast into the upper Midwest
and drags a surface front into the coastal waters. A modest
northeast flow is expected in the wake of the front. Elevated rain
chances will continue into the weekend as the front stalls out
over the northwest Gulf.
.PRELIMINARY POINT TEMPS/POPS...
AEX 54 69 62 71 / 20 40 60 90
LCH 58 70 64 72 / 10 60 60 90
LFT 57 70 64 73 / 10 50 50 90
BPT 60 70 64 72 / 10 60 80 90
GM...Small Craft Advisory from 6 PM Wednesday to noon CST Thursday
Small Craft Exercise Caution from Wednesday morning through
Wednesday afternoon for GMZ430-432-435-455-475.
Small Craft Advisory from 10 AM Wednesday to noon CST Thursday
Small Craft Advisory from 6 PM Wednesday to 6 AM CST Thursday
Small Craft Exercise Caution Thursday morning for GMZ430-432-435.
Area Forecast Discussion
National Weather Service Tucson AZ
313 PM MST Tue Dec 25 2018
.SYNOPSIS...Expect unsettled weather the rest of this week, with
much cooler temperatures and periods of valley rain and mountain
snow showers. The first system will bring widespread valley rain and
mountain snow with gusty winds at times this evening into Wednesday.
A colder system should arrive Thursday night into Friday with snow
levels potentially near valley floors. The coldest nights of the
season so far are expected this weekend with widespread sub-freezing
temperatures even across the lower deserts.
.DISCUSSION...Isolated showers and thunderstorms were starting to
develop across western Pima county around Ajo and Why this
afternoon. Latest HRRR solution continued to suggest that this
development will expand this evening, with the bulk of the
precipitation occuring tonight into early Wednesday. That said, will
keep the Winter Weather Advisory for snow accumulations posted this
evening into Wednesday for elevations above 6000 feet. Otherwise,
expect some improving weather conditions during the afternoon
Wednesday through much of Thursday. This will be a brief break in
the weather as another system brings more valley rain and mountain
snow by Thursday evening into Friday. This next system will usher in
much colder air setting the stage for the coldest nights of the
season so far, and the potential for some snowflakes in the lower
desert valleys on Friday. Unsettled weather may continue over the
weekend as models continued to depict another system hanging around
the region. Will keep the slight chance of precipitation in the
forecast this weekend with below normal temperatures continuing.
Thereafter, yet another system might impact the region for the start
of the New Year.
.AVIATION...Valid through 27/00Z.
Expect -SHRA to develop west of Tucson late this afternoon becoming
widespread valley -SHRA and mountain -SHSN late this evening into
Wednesday morning. Some occasional thunder will be possible in the
storms west of Tucson this late this afternoon. MVFR conditions will
be likely this evening into Wednesday afternoon especially in the
presence of -SHRA and near the higher terrain. Winds this afternoon
into the late evening will be out of the southwest at 15-22 kts with
gusts up to 30 kts becoming southerly/southwesterly at 8-12 kts
overnight into Wednesday morning. Wednesday afternoon winds will
pick up again out of the southwest 12-18 kts with gusts to 25 kts.
Aviation discussion not updated for TAF amendments.
.FIRE WEATHER...Expect widespread valley rain and mountain snow by
this evening and continuing into Wednesday. Wednesday night into
Thursday afternoon precipitation chances move to the White Mountains
and along the Arizona/New Mexico border. Valley rain and mountain
snow returns from Tucson eastward Thursday night into Friday. Over
the weekend there is a slight chance of snow showers in the White
Mountains, then potentially more valley rain and mountain snow by
the middle of next week. Gusty southwest to northwest winds will
prevail this afternoon and tomorrow afternoon. Otherwise, 20-foot
winds will be terrain driven under 15 mph with the exception of
Sunday which will see easterly winds.
Winter Weather Advisory from 5 PM this afternoon to 5 PM MST
Wednesday above 6000 feet for AZZ510>514.
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