Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 12/07/22

Area Forecast Discussion

National Weather Service Northern Indiana

 645 PM EST Tue Dec 6 2022

.SYNOPSIS...
Issued at 637 PM EST Tue Dec 6 2022

The clouds will stick around for the next several days. There is
a small chance for some fog and drizzle at times tonight, mainly
along and east of Interstate 69. The next chance for measurable
rain will be Thursday night.


&&

.SHORT TERM...(This Evening through Wednesday)
Issued at 252 PM EST Tue Dec 6 2022

Stratus will remain entrenched across the area through the period as
frontal boundary resides to the SE of the area and yet another wave
moves along it tonight into early Wed. Big question remains how
much, if any, light rain/drizzle may occur with this feature.
Inversion and drier, near sfc layer, kept any precip at bay with a
similar setup tonight. ACARS sounding at KFWA shows saturated
layer from just under 850 mb down to 950 mb with a shallow layer
of somewhat drier air still in place and base of the inversion
near/just below the top of the stratus deck. While CPDs do drop to
10 mb or less with this feature, flow is nearly parallel to the
pressure surfaces for all but far SE locations and even there it
is on the weaker side with much better potential SE of the area.
Narrow band of showers has developed across southern IL which is
edging NE with CAMs all suggesting this either weakens as it comes
in or stays intact and maybe clips the SE as noted. Even if
something occurs, it will be light and brief with no more than low
chc pops warranted. Most likely will be face with at least some
patchy fog across at least the SE third of the area. May not be
far enough NW with the coverage and some potential for pockets of
dense fog, but will defer to eve shift to monitor trends.

Any lift will move out quickly late tonight with dry conditions to
dominate. Challenge on Wednesday will be if any breaks can occur in
the cloud with inversion heights lifting some, but still holding
strong just below 900 mb. Will keep at least mostly cloudy skies in
through the afternoon.

&&

.LONG TERM...(Wednesday Night through Tuesday)
Issued at 252 PM EST Tue Dec 6 2022

The first, more substantial, wave will eject from Nevada at the
start of the period and move rapidly into the area Thursday night
into early Friday. Much better forcing, upper level dynamics and
moisture return to bring at least a period of rain to the area, with
best chances/highest QPF residing across the N and W. With
increasing confidence and persistence in trends pops have been
increased to categorical with most locations to see between a
quarter and half inch of precip. Although overnight lows will dip
into the mid 30s across the far N late Thur night,wet bulb temps
should remain just warm enough to keep the precip as all rain.

Will keep the weekend dry although there will be another fast moving
trough Saturday afternoon that some med range models hint could
bring some light rain. Main focus remains on much stronger longwave
trough set to eject towards the region near or just outside the
period. Models seem to keep with a slower and slower trend, maybe
waiting till mid week before heading this way. NBM placed likely
pops late Mon afternoon into Tuesday, which based on the trends I
am somewhat skeptical on, but will leave in place with a good
chance these will be pushed back.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 637 PM EST Tue Dec 6 2022

Fog and drizzle developed at KFWA along a stationary front this
evening, bringing IFR/LIFR ceilings and visibilities a bit
earlier than planned. Expect these to linger as the boundary
eventually begins to shift southeastward Wednesday morning-allowing
ceilings to return to higher-end IFR/MVFR. Otherwise, expect MVFR
conditions at KSBN through the night with ceilings hovering
around 2000 ft.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SYNOPSIS...MCD
SHORT TERM...Fisher
LONG TERM...Fisher
AVIATION...MCD


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Area Forecast Discussion

National Weather Service Phoenix AZ

 431 PM MST Tue Dec 6 2022

.UPDATE...Updated 00Z Aviation Discussion...

&&

.SYNOPSIS...
A weak weather system will pass through the region today and
Wednesday with chances for light showers focused over the high
terrain north and east of Phoenix. By Wednesday night into
Thursday, a gradual drying trend will begin and last through the
rest of the week, while temperatures stay slightly below normal
through the upcoming weekend.

&&

.DISCUSSION...
Dew points are still holding in the low to mid 50s this afternoon
across South-Central AZ, including the Phoenix area, while drier
westerly winds have lowered values into the 30s and 40s across
Southwest AZ and Southeast CA. Aircraft soundings out of Phoenix
show drier air has worked into the area, especially in the 700mb
layer, but enough moisture remains in the boundary layer for low
cloud development. A minimal amount of SBCAPE is also supporting
some convective cumulus development this afternoon, with some
light low-topped showers seen north of Maricopa County. Precip
chances through the rest of this afternoon and evening are
generally 15% or less in the Phoenix area to up to 20-30% in the
Foothills on the northern edges of Phoenix and in the high terrain
to the east. Any shower is likely to be brief and produce minimal
rainfall (<0.10"). The shower chances will continue through
Wednesday as the region is still downstream of an upper low moving
down the west coast, but still rainfall Wednesday should remain
light and focused north and east of Phoenix.

The aforementioned low moving down the coast is projected to
eventually eject east-northeastward, passing north of the local
CWA and into the Colorado Rockies by the end of the day Wednesday.
Following the passage of the trough axis, much drier air will move
in with NBM supporting a steady decline of dew points through
Thursday, back down into the 30s across nearly all lower desert
locations. The drier boundary layer conditions, along with drier
air aloft, will support better radiational cooling overnight and
cooler morning lows through the rest of the week and weekend. NBM
MinT forecasts have most population centers falling into the low
to mid 40s, with more rural and unsheltered areas dipping into the
30s, beginning Thursday morning. These cool mornings, with
seasonal afternoon temperatures in the 60s, and tranquil
conditions will then persist through at least Saturday.

The next potential weather system that could bring more widespread
precipitation may impact the region at some point early next week,
but model ensemble spread remains quite high. At the moment, there
seems to be a fairly even three way split between a deeper system
moving through our region bringing good precipitation chances, one
that skirts by across the northern portions of the region, and the
other largely bypassing the region well to the north. There is
also potential for this trough to bring the coldest temperatures
of the season so far, including lower desert freezing
temperatures, and even snow chances for some peaks and ridges in
Southern Gila County. We will need to wait another few days to
have a better idea on which solution to expect. Either way,
ensembles heavily favor temperatures staying below normal through
the first half of next week.

&&

.AVIATION...Updated 2330Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:

SCT-BKN cloud bases with CIGS between 5-7 kft will continue to
prevail through early tomorrow afternoon. Otherwise, mainly
tranquil conditions expected with light winds and directions
following a diurnal pattern. There is still a 10-20% probability
of a few showers through tomorrow morning, however, confidence is
low to include in TAF at this time.

Southeast California/Southwest Arizona including KIPL and KBLH:

Mainly light westerly winds along with FEW-SCT mid-level clouds
will continue to prevail across the TAF sites through the period.

&&

.FIRE WEATHER...
A weak weather system will bring chances for mainly high terrain
showers through midday Wednesday as moisture levels remain
elevated. The current high moisture levels will gradually
decrease later this week with MinRHs above 40% through Wednesday
falling briefly to 25-35% Friday into Saturday. Winds will
overall remain light over the next several days, while
temperatures run slightly below normal. This quiet weather
period should last through the weekend before more unsettled
weather conditions will be possible early next week.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

$$

DISCUSSION...Benedict/Kuhlman
AVIATION...Lojero
FIRE WEATHER...Kuhlman