Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 08/27/19

Area Forecast Discussion

National Weather Service Denver/Boulder CO

 918 PM MDT Mon Aug 26 2019

.UPDATE...
Issued at 912 PM MDT Mon Aug 26 2019

No significant changes to the current forecast for the tonight
and Tuesday period. Watching another surface cool front in the MT
vicinity late this evening, which is expected to move onto the
eastern CO plains during the late Tuesday morning hours between
16z-18z. The cool front is mainly dry, however the short term
models still introduce isolated light rain showers over the far
eastern plains with the entry of the cool front. Cool temps are
still on track for Tuesday with dry conditions expected for the
mountains, foothills and Urban Corridor.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 220 PM MDT Mon Aug 26 2019

The northeastern Colorado plains and urban corridor continue to
enjoy a cool day under a strong post-frontal inversion, evident
on ACARS soundings around 710-730 mb. Above this inversion and
into the northcentral mountains, a dry northwesterly flow and
lower dew points continue to bring a dry day to the high country.
Also noted in water vapor imagery, is an increase in moisture
upstream over western Colorado, moving over Summit County into
Park County and over the Palmer Divide. This little ripple
combined with the higher terrain of the Palmer may still be
enough to bring a shower or thunderstorm over this area this
evening. Otherwise, mostly clear skies are expected most of the
night with winds returning to semi drainage.

A shortwave upper trough dropping down into the northern Great
Plains will push another cool front into the northeastern Colorado
plains late tonight into early tomorrow morning. Stratus is once
again expected to push into the area, but perhaps not as far west
into the urban corridor this time. With a jet nearby, and some
elevated CAPE, may see a few showers out over the northeastern
plains early tomorrow morning. Viewing forecast soundings, seems
like it will take a while for the stratus to burn off, and have
lowered forecasted high temperatures for this reason. Mountains
will continue to be warmer and drier, with a slight chance of
thunderstorms again over the far southern foothills and east onto
the Palmer Divide late afternoon.

.LONG TERM...(Tuesday night through Monday)
Issued at 220 PM MDT Mon Aug 26 2019

There will be strong subsidence on Wednesday behind a departing
trough to the east and a developing ridge over the Desert
Southwest. Temperatures will warm to around 5 degrees above normal
and may hit 90 in Denver. There will be very dry air in place
especially over the higher terrain with model soundings
indicating precipitable water values between 0.15-0.2 inches. At
the surface, relative humidities will drop to around 10 percent in
the mountain valleys and teens across the foothills. With west to
northwest winds around 15 mph gusting to 20-25 mph, there will be
elevated fire weather conditions with the potential to reach red
flag criteria. At this time, it appears winds will be slightly
below criteria so a Fire Weather Watch was not issued.
Nevertheless, it would be a bad day to burn over the higher
terrain. Across the plains, there will be low humidities but light
winds so there will be lower fire weather conditions.

Highs will warm around 5 degrees on Thursday as the ridge aloft
strengthens. There will be a slight increase in moisture but
without a substantial feature to generate lift, showers and storms
will be very limited in coverage. Lighter winds at the surface
than Wednesday will lead to lower fire weather conditions.

A cold front will move through eastern Colorado on Thursday night
bringing in better moisture with precipitable water values
increasing to 0.75 to 1 inch on Friday. A weak shortwave passing
through northern Colorado Friday afternoon will create showers and
storms with the highest coverage of storms being over the eastern
plains during the evening. There is low confidence in storms on
Saturday as ridging builds overhead despite the moisture that
remains in place. Global models develop a very strong ridge over
the Four Corners region on Sunday with 500 mb heights possibly
reaching 597 dm. This should keep conditions mainly dry with hot
temperatures.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 912 PM MDT Mon Aug 26 2019

Easterly surface flow is expected to prevail across the eastern
plains and in the vicinity of the terminals for much the overnight
period before a brief period of southerly drainage flow between
08z and 13z. VFR conditions are expected overnight. A surface
cold front will move onto the CO plains and Front Range terminals
in the 15z to 18z timeframe and provide northeasterly winds for
much of Tuesday. The cool front is mainly dry, however a few light
rain showers can be expected over the far eastern plains of
Colorado after 15z Tuesday.

&&

.FIRE WEATHER...
Issued at 220 PM MDT Mon Aug 26 2019

Fire weather concerns remain over the high mountain valleys on
Tuesday as a warm and dry airmass remain. This is especially true
of Middle and western South Parks where humidity will be in the
low to mid teens, with winds gusting around 20 mph at times in the
afternoon. Winds look to stay just below criteria however.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

UPDATE...Fredin
SHORT TERM...Kriederman
LONG TERM...Danielson
AVIATION...Fredin
FIRE WEATHER...Kriederman



Area Forecast Discussion

National Weather Service Honolulu HI

 353 PM HST Mon Aug 26 2019

.SYNOPSIS...
Trade winds will gradually decrease over the next couple of days
as high pressure north of the state weakens. A typical rainfall
pattern will continue through Tuesday, with showers favoring
windward slopes of all islands and the leeward slopes of the Big
Island during the afternoon. On Wednesday and Thursday, trades
could be weak enough for sea breezes to produce isolated
afternoon showers over some leeward terrain. Strengthening trade
winds are expected during the weekend.

&&

.DISCUSSION...
The stable trade wind flow is slowly declining. Trades are being
driven by a surface high centered far northeast of the state.
This feature is being eroded by a North Pacific trough far north
of the islands, leading to the decreasing trend in the locally
breezy trade winds. A mid level ridge is maintaining the stable
conditions, as evidenced by a well-defined inversion between 6,500
to 8,000 ft on the afternoon soundings and recent aircraft data.
The stable trade wind flow has resulted in a typical rainfall
pattern today. A small pocket of moisture that moved through
earlier kept showers more active on windward Big Island compared
to the rest of the state, and spotty showers have been flaring
along the heated South Kona slopes of the Big Island this
afternoon.

Trades will continue their slow decline tonight as two,
unimpressive pockets of low level moisture affect windward
portions of some islands. One area will produce modest rainfall on
windward Kauai, while a second will likely be focused across
windward east Maui and northern Big Island.

Trades will gradually decline through Wednesday as surface high
pressure north of the state is further weakened. The North Pacific
trough eroding the high will also weaken the mid level ridge over
the islands. Conditions will remain generally stable, but
additional small areas of moisture moving along the trade wind
flow could produce heavier rain rates, mainly during the overnight
hours. In addition, trades may weaken enough to allow more
widespread sea breezes and increased afternoon shower chances
across leeward terrain by Wednesday.

The suppressed trade wind flow will continue on Thursday. We
could see an increase in shower activity on the Big Island during
this time as a slug of deeper tropical moisture passes over or
just south of the area.

Trades will rebuild late Friday and next weekend as high pressure
strengthens north of the state. The GFS and ECMWF are suggesting a
another area of moisture providing a boost to windward showers
during the weekend, but confidence remains low at this time.

&&

.AVIATION...
A high pressure ridge north of the state will keep moderate to
breezy trade winds in the forecast through tonight. Wind speeds
will remain strong enough for low-level turbulence south through
west of all mountains, so AIRMET Tango will likely continue for
those areas into this evening. Clouds and showers will continue to
favor windward slopes of all islands and leeward slopes of the Big
Island as the trades slowly diminish, with brief periods of MVFR
ceilings possible.

&&

.MARINE...
Afternoon ASCAT pass did reveal a small area of locally strong
trade winds over the Alenuihaha Channel and south of the Big
Island. Thus, the Small Craft Advisory (SCA) has been extended
through tonight for the typical windy areas around Maui and the
Big Island. Trade winds should drop below SCA levels later
tonight in response to a front passing far north of the state. By
mid week, winds are expected to be in the gentle to moderate
speeds with land/sea breezes possible near select leeward coasts. A
new high will form north of the state by the end of the week and
should result in a slight uptick in trades over the weekend.

Rough choppy surf along east facing shores will steadily decrease
over the next few days with very minimal energy expected by the
middle of the week as the trade winds weaken. Surf along south
facing shores will gradually increase Tuesday, as the forerunners
of a new southwest swell arrive. This swell is expected to peak
below advisory levels along south facing shores Wednesday into
Thursday and gradually decrease through the end of the week. This
swell will be inconsistent due to the many southwest Pacific
Islands the swell needs to travel through to arrive in Hawaii.

Models continue to show a long fetch of strong to near gales
associated with a low developing north of the state Tuesday into
Wednesday of this week. This should bring an increase in surf
along north facing shores and exposed east facing shores by this
weekend.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 AM HST Tuesday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.

&&

$$

DISCUSSION...Wroe
AVIATION...TS
MARINE...Kino



Area Forecast Discussion

National Weather Service Blacksburg VA

 1105 PM EDT Mon Aug 26 2019

.SYNOPSIS...
High pressure over the northeast United States will remain
wedged down the Appalachians, keeping temperatures below normal
through the first part of the week, along with a chance of
showers and some patchy fog. A cold front will then move through
the region on Wednesday with showers and thunderstorms, followed
by a return to fair and warmer weather for the end of the week.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 1045 PM EDT Monday...

Low clouds remain banked against the east side of the
Appalachians as an area of mid/upper level moisture slowly
advances east from the west side of the Appalachians. This
mid/upper level moisture is associated with approaching front
aloft. Radar imagery indicates a solid area of light rain from
WV into eastern TN. Rainfall amounts within this band of rain
have generally averaged from a few hundredths to as much as a
tenth of an inch over the last 6 hours. For the evening update,
raised pops considerably across the western CWA to account for
this persistent light rain. Look for this area of rain to
gradually overspread areas west of the Blue Ridge before 3AM,
then the question is whether this activity spreads east of the
Blue Ridge for Tuesday morning.

Anticipate the lingering wedge to maintain the cool
temperatures. Squeeze play between the front approaching from
the west and the easterly flow will continue to favor abundant
cloud cover. This should also ensure potential for light rain or
sprinkles as we transition into the day Tuesday with best chance
for measurable rainfall along and west of the Blue Ridge.
Showers will linger through mid-day Tuesday with some gradual
improvement during the afternoon. However, the wedge will not be
dislodged and will continue to linger over the region and keep
a good amount of clouds through the afternoon.

Lows tonight will generally be in the 60s. Highs tomorrow will
be around 80 east of the Blue Ridge, with mid/upper 70s to the
west.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 236 PM EDT Monday...

Expect increasing humidity and shower chances Tuesday night into
Wednesday with upper difluent flow well in progress. This is going
to aid lift over the region resulting in at least a scattering of
showers. The main front arrives Wednesday and shifts east of the
area by Wednesday evening. Several models are focusing on two areas
of showers/few storms, one along the western slopes and then lee of
the Blue Ridge with potential jump set up, where the New River
Valley into the I-81 corridor from Roanoke to Lexington see less
coverage. Best support aloft shifts north and east of the area by
late afternoon. Parameters favor a scattered to broken line of
convection east of the mountains. Decent shear but lower CAPEs limit
severe potential but a few storms could bring some strong wind
gusts, especially across the Virginia piedmont.

Things dry out Wednesday night with lower humidity and plenty of
sunshine for Thursday.

Highs Wednesday will be close to normal, ranging from the upper 70s
to lower 80s in the mountains, to mid to upper 80s east. Lows
Thursday morning will be in the mid to upper 50s mountains, to lower
to mid 60s east.

Plenty of sun and drier air will allow temps to warm to near normal
again Thursday, but dewpoints will be about 5 to 10 degrees lower.

Clear skies Thursday night and light wind will allow temps to sink
into the lower 50s in the mountains, some 40s likely in the deeper
valleys, or high elevation valleys like Burkes Garden, to around 60
east.

Confidence in this forecast is average for shower/storm chances
especially Wednesday, and higher on temps.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 1255 PM EDT Monday...

Previous forecast and latest models are in general agreement in
keeping area on southern fringe of westerlies Friday into Saturday
before amplification increases into Sunday and Monday. Expect
temperatures at or just above normal for Friday-Saturday, the near
normal Sunday-Monday.

Should be mainly dry across the area Friday-Saturday despite a weak
frontal boundary  moving across. Surface front stall south of us
into Sunday with upper trough digging into the mid-Atlantic. At the
moment appears TS Dorian to stay south of us and weaken and or be
picked up by the digging trough early next week.

Still enough moisture arriving atop the frontal boundary will keep
threat of showers/few thunderstorms around Sunday-Monday.

Confidence is pretty good for Friday-Saturday, then average for
Sunday-Monday.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
As of 1030 PM EDT Monday...

Easterly low level wind flow will maintain low clouds through
the night and into the day Tuesday. A front aloft will provide
mid/upper level cloud layers with potential for light rain.
Overall, expecting at least MVFR CIGS through the forecast
period with some improvement Tuesday afternoon.  The best
chance for precipitation will be along and west of the Blue
Ridge which will favor some restriction of visibility...
favoring the MVFR category late tonight and early Tuesday.

Winds will generally be light with no significant impact to
aircraft operations expected. Overall confidence in the forecast
is moderate to high.

.Extended Aviation Discussion...

More typical late summer conditions will return by midweek.
Scattered showers and thunderstorms with MVFR conditions are
expected Tuesday. On Wednesday, scattered showers and
thunderstorms are expected along and ahead of a cold front
crossing through the region. Finally, VFR conditions should
prevail behind the front on Thursday.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.

&&

$$
SYNOPSIS...MBS
NEAR TERM...MBS/PM
SHORT TERM...WP
LONG TERM...WP
AVIATION...PM