Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 08/17/22

Area Forecast Discussion

National Weather Service Phoenix AZ

 445 PM MST Tue Aug 16 2022

.UPDATE...Updated 00Z Aviation Discussion.

&&

.SYNOPSIS...
Temperatures will climb to near to slightly above
normal through Wednesday, with daily isolated showers and
thunderstorms. Beginning late Wednesday, deep monsoonal moisture
will return to southern Arizona leading to much better chances for
showers and thunderstorms. Heavy rainfall and localized flooding
are likely to impact portions of south-central and eastern Arizona
later this week, with chances peaking on Friday through Sunday.
Temperatures are also forecast to cool to well below normal with
highs across a good portion of the lower deserts falling into the
nineties or even upper eighties by Friday.

&&

.DISCUSSION...
A broad area of ridging remains in place across the northern
portions of the United States and Canada with near or below normal
heights across the Desert Southwest. There are several mesolows in
the area, including one southeast of Phoenix that will drift up
towards our forecast area this afternoon. Further east near the
Big Bend area of Texas, a much stronger upper level low is slowly
drifting west, but for now is not impacting the forecast area.
Visible satellite shows partly sunny skies, with a few
thunderstorms popping up over the higher terrain. ACARS soundings
show a cap at the top of the boundary layer, which should keep
storms from proliferating in the valleys too much for now,
especially near Phoenix.

For this afternoon we are looking at scattered storms developing
over the higher terrain, especially southeast California where
moisture and instability profiles are a bit better. HREF guidance
shows high confidence (50-70%) chance of gusty outflow winds of at
least 35 kts over southeast California today with a lower
(20-40%) chance of such winds for the rest of the forecast area.
Because PWAT remains elevated at 1.7-2.1", locally heavy rain will
also be a threat. Further, with weak winds aloft, storms will not
move very quickly. For the Phoenix area, sufficient
destabilization for storms is in question, but it does appear that
a few storms will pop up this afternoon or evening with a 10-20%
chance of rain in any given location. As for temperatures, warm to
hot conditions will continue through Wednesday with highs in the
103-107 range for the lower deserts, but with elevated moisture
levels it will not feel like our more typical dry heat.

For the Wednesday through early Friday period we will see an
increasing storm threat in response to the previously mentioned
upper level low centered near the Texas/Mexico border. Several
factors will work together to enhance the storm threat as it
approaches. First, mid level winds in the 600-400 mb layer will
shift to northeast and strengthen. This will act to strengthen
wind shear and the steering flow from off the higher terrain.
Second, an influx of deep moisture on Wednesday will send PWAT
values close to 2" for much of the area. Third, there will be some
forced ascent as the storm system approaches. These factors
should allow for numerous high terrain storms to develop along the
Rim with a decent (30-50%) chance of these storms moving into the
valleys of Arizona from the northeast during the afternoon hours.
Should this scenario unfold all of our typical monsoon hazards
would be possible, but wind and dust typically dominate in
northeast flow events. Heading into Thursday and especially Friday
it may be that excessive cloudiness limits storm chances
somewhat, but this outcome will depend on what happens in the
previous days in large measure. There is also still some
uncertainty with respect to the track of the low pressure area,
and if it tracks further south than modeled our risk of storms
would diminish.

Friday will be a transitional day for what looks to be the main
event and potentially a significant precipitation event for
south-central Arizona. Setting the stage will be a strengthening
trough to the northwest of the forecast area, which will put
southern Arizona under excellent diffluent flow aloft with
strongly forced ascent, especially on Saturday. Low level moisture
transport will strengthen, with PWAT climbing above 2", which is
near the max NAEFS climatology for this time of year and above the
99% percentile. Further, due to the proximity of the trough and
the other upper level low (which will still be south of the area),
wind shear will increase. Taken together, these factors strongly
support widespread and potentially heavy precipitation. ECMWF EFI
precipitation depicts values of 0.7-0.9 across the area on
Saturday. The shift of tails is relatively minimal, and a perusal
of the ensemble reveals good consistency in precipitation totals
compared to usual. What this likely means is higher confidence in
most locations getting a good soaking, rather than a few locations
getting a lot of rain while most others get little to none.
Accordingly, WPC QPF continues to show potentially large storm
totals of 1-3" between Friday and Sunday evening for south-central
Arizona. Lower totals of less than 1" are forecast for SE
California during this period. It is anticipated that a flood
watch will eventually be needed for south-central Arizona if the
forecast remains consistent.

Temperatures will also cool off considerably by Friday with highs
falling well into the 90s over a good portion of the lower deserts.
If models end up being correct with the amount of clouds and
rainfall over the area later this week, some lower desert areas
likely won`t get out of the 80s on Saturday. The NBM even has a 20%
chance that the Phoenix area fails to reach 85F for the high on
Saturday. Widespread rain chances may also linger into Sunday, but
models mostly show waining upper level support by early Sunday while
the disturbance to our south weakens considerably. By early next
week, there is fairly good ensemble agreement our region will see a
gradual drying trend with northerly upper level flow becoming more
dominant.

&&

.AVIATION...Updated 2345Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Current light westerly winds are expected to continue thru shortly
after midnight, then becoming typical easterly drainage winds
thereafter. Thunderstorm chances to remain low thru tonight as most
activity will remain focused across the high terrain. It`s not out
of the question to see a few isolated vicinity showers pop up across
the metro this evening, but confidence (10-20%) chance remains too
low to include anything more then VCSH in the TAFs at this point.
Chances are a little more likely (20-30% chance) that current
westerly winds could be enhanced a bit from outflows from t-storms
over SW Maricopa County, but confidence remains low on if/when any
outflows impact the terminals, Expect SCT-BKN clouds to remain
mostly aoa 8 kft through this evening. After winds shift to easterly
late tonight, expecting these easterly winds to continue thru early
afternoon Wednesday, then switch to typical westerly winds during
the mid-afternoon hours.

A better chance (40-60%) exists for t-storms impacting the terminals
Wednesday afternoon/evening as moisture/instability increases across
the region. Have added VCTS in the TAFs at this point (given
uncertainties in timing), with winds likely shifting to a
northeasterly direction. There are also indications that lighter
SHRA/isolated T-storm activity could persist well into Wednesday
night as well.

Southeast California/Southwest Arizona including KIPL and KBLH:
Winds through the period will mostly favor a southerly to
southeasterly component outside of any potential thunderstorm
outflows. It appears that the t-storm activity that developed across
the region is diminishing at this hour, thus have only included VCSH
in the 00Z TAF suite for the next few hours, with only a remote (10-
20%) chance that t-storms will directly impact either SE CA
terminal. Chances for SHRA/t-storm activity increase again Wednesday
afternoon/evening, but remain too low (10-20%) to include anything
more than VCSH in the TAFs at this point.

&&

.FIRE WEATHER...
Daily chances for mostly isolated thunderstorms are expected
through Wednesday afternoon areawide with chances increasing
across southeast and south-central Arizona by Wednesday evening.
A weather disturbance along with deep tropical moisture are then
expected to impact much of Arizona as early as Thursday, likely
peaking at some point Friday into Saturday. This will provide
widespread wetting rains and cooler temperatures across the area,
especially across southeast and south-central Arizona. Humidities
will remain fairly elevated through mid week with afternoon
minimum RH values into a 25-30% range, before climbing back upward
later this week as even higher moisture levels return and
temperatures cool off. Impacts from thunderstorm activity will
increase starting Thursday with strong winds, heavy rainfall, and
flooding all possible through the upcoming weekend. Winds through
the majority of the period will remain light, with the exception
of nearby thunderstorms or thunderstorm outflow generating
stronger gusts.

&&

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

$$

DISCUSSION...Hodges/Kuhlman
AVIATION...Percha
FIRE WEATHER...Kuhlman



AREA FORECAST DISCUSSION

National Weather Service Raleigh NC

 900 PM EDT Tue Aug 16 2022

.SYNOPSIS...
A cool and moist northeasterly flow under a wedge of high pressure
over the Appalachians will remain in place tonight and much of
Wednesday. This high pressure will weaken on Wednesday as it slowly
moves toward the coast by Thursday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 900 PM Tuesday...

The skies remain variably cloudy this evening with only an isolated
shower or two remaining in the NE. Temperatures were already in the
mid 60s to mid 70s with a light northerly flow in the cool air mass
across the region. No need to make changes other than to update the
hourly temperatures and remove POP in the south and west through
midnight.

Previous discussion issued at 330 PM Tuesday...

At the base of a broad mid/upper-level cyclone developing across the
lwr Great lakes/nrn Mid-Atlantic/and Northeast, low amplitude/
weakly-perturbed --and moist-- wnwly to wly flow will be directed
from the cntl Plains/mid MS Valley to the Carolinas.

At the surface, a wavy front draped from about 50-100 miles off the
NC coast swwd across the SC Lowcountry may drift slightly east
overnight, while high pressure otherwise will continue to extend
south across NC.

Visible satellite and ACARS soundings depict multiple cloud layers
in a still-moist profile in the lowest 10-15 thousand ft over NC.
While the lowest of these cloud layers, stratocumulus between 2000-
5000 ft, will likely scatter as drier air in that layer filters ssw
from the Mid-Atlantic, forecast soundings suggest the mid and also
periods of high cloudiness will likely persist. And while an
isolated to widely scattered shower cannot be entirely ruled out
anywhere in cntl NC through this evening, the relative best chance
will be in the Coastal Plain this afternoon from the ongoing cells
from sern VA swwd through ern NC, with overnight lows in the 60s.

&&

.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
As of 250 PM Tuesday...

Ridge amplification over wrn NOAM will result in downstream trough
amplification and falling heights from the srn Canadian Prairies to
the Southeast. That amplification will also re-orient mid/upper-
level flow from wnwly to wswly from the mid MS Valley to the Mid-
Atlantic, through which an associated upper level jet streak will
strengthen while migrating across and offshore the srn mid-Atlantic
late Wed-Wed night. The models indicate an elongated area of upper
divergence accompanying that jet streak will overspread the
Carolinas late Wed-early Wed night.

At the surface, low pressure will move slowly away from the coast of
the Carolinas, while the trailing front retreats slightly nwd across
the Savannah Basin. To the north of the frontal zone, an inverted,
lee trough will develop from the Upstate of SC nwd across the NC
Foothills/wrn Piedmont, while high pressure over the Mid-Atlantic
and associated nely flow across cntl NC otherwise weaken.

While this pattern will result in periods of forcing for ascent,
that lift will be working upon anticyclonic flow and a generally
stable environment over cntl NC, related to the lingering surface
ridge. A dry forecast, but with continued periods of mid/high-level
cloudiness, will result. The lingering influence of the ridge and
nely flow will also favor continued below average temperatures:
highs generally low-mid 80s and lows in the upr 50s to mid 60s.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
As of 315 PM Tuesday...

An upper low over New England early Thu will lift to the north
Thu/Thu night. Another northern stream low will dive south from
central Canada into the northern Plains/Western Great Lakes, where
it will sit through Friday before gradually migrating eastward into
the OH Valley over the weekend. The upper trough axis will shift
west from over the eastern US to west of the mtns, becoming anchored
with the low over northern Plains/Western Great Lakes. By Monday,
the low should be over the central/eastern Great Lakes, while the
trough axis extends south-southwest, roughly along the Appalachians.
The medium-range models diverge with respect to this low and trough
beyond Monday.

At the surface, while a deep low lifts slowly north through New
England Thu/Thu night, an area of low pressure will linger off the
NC coast over the Atlantic. Relatively high pressure will be in
place over central NC. Beyond Thu the surface pattern becomes a bit
more variable and uncertain, but an inverted trough or relative area
of low pressure is expected either along the Southeast/Carolina
coast or inland over the Southeast and Carolinas.

The driest day should be Thu while the low lingers over the
Northeast and high pressure keeps most disturbances away from the
area. Expect increasing chances for showers/storms as the trough
shifts west. Friday appears to be the wettest day for now, but the
medium-range model solutions diverge quite a bit with respect to
precipitation over the weekend into early next week. Looking ahead,
middle of next week (Tue, Wed, Thu) could be wet.

As for temperatures, highs could remain below normal through the
weekend, while lows may creep up from below normal Thu night to just
above normal through early next week.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 720 PM Tuesday...

Low overcast at terminals has lifted/scattered to VFR this
afternoon/evening. A southward moving boundary over the northern
Coastal Plain continues to produce some scattered light showers
along with a brief MVFR ceiling. As for tonight, a push of drier air
around around 2-3kft will usher in from VA into Wednesday morning,
but depending on the timing, may lead to a period of MVFR ceilings
before it moves in from the north. FAY may have the best chance to
see the MVFR ceiling, but even there, confidence is too low to
introduce any restrictions with the 00z TAF package. VFR conditions
are expected through Wednesday evening with northeasterly winds
between 5-10kts. -Swiggett

Outlook: A chance of sub-VFR conditions and especially afternoon-
evening showers/storms will return for Friday through the weekend.
-MWS

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...PWB/Kren
NEAR TERM...PWB
SHORT TERM...MWS
LONG TERM...KC
AVIATION...Swiggett/MWS



Area Forecast Discussion...UPDATED

National Weather Service Springfield MO

 948 PM CDT Tue Aug 16 2022

Key Messages:

1. Showers and thunderstorms develop tonight across southern
Missouri through Wednesday morning. Training thunderstorms may
result in localized flooding.

2. Isolated strong to severe thunderstorms possible this evening
across far southwestern MO and southeastern KS.

3. Cooler temperatures overspread the area from Wednesday through
the weekend.

4. Additional rain chances this weekend into early next week.

.MESOSCALE DISCUSSION...
Issued at 914 PM CDT Tue Aug 16 2022

A band of showers and thunderstorms has set up from southeast
Kansas into southwest Missouri, which is where the high res
guidance indicated it, however it has arrived slightly ahead of
schedule. Therefore we have increased the pops and qpf earlier to
account for this.

Shortwave energy was currently located across eastern Kansas and
was interacting with a very strong instability gradient. 00z SGF
sounding measured 1000j/kg of MU cape, generally above 750mb,
along with 1.85in of PW. However areas to the southwest were
substantially more unstable. A 01Z Amdar sounding out of Tulsa
measured 2500j/kg of MU CAPE along with a PW of 1.98in. A surface
low across northeast Oklahoma has a trough extending into
southwest Missouri with northeast to east winds common.

General expectations are that showers and storms will continue in
a corridor from extreme southeast Kansas, to Joplin, Springfield
and Branson. This area should then continue to slide towards the
West Plains area later tonight. Models do show a decent amount of
backbuilding with this activity overnight however there is a lack
of a low level jet as the Tulsa sounding only showed about 15kts
at 850mb. Therefore its unclear how much backbuilding will occur as
the instability gradient shifts south with time. Areas north-
northeast of Springfield may miss out on the bulk of this
precipitation.

While there is decent effective bulk shear (measured 34kts), the
waning instability will likely keep any severe threat very low.
However the lightning has been impressive and will be very
widespread and frequent this evening. Given the high PW values,
heavy rainfall rates will occur at times and a widespread 1-3
inches of rainfall looks likely in the Joplin-Springfield-Branson
corridor. High flash flood guidance/drought will likely preclude
any widespread flooding however a few instances are certainly
possible, especially in urban/poor drainage areas and the
typically sensitive low water crossings that are common across
the Ozarks.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 245 PM CDT Tue Aug 16 2022

Much of our northeastern CWA observed rainfall totals of 1-3
inches this morning, with pockets of around 4 inches in the Lake
of the Ozarks region. This activity has persisted but weakened as
the low level jet fueling it has lessened.

Current surface observations and satellite imagery reveal the
surface low pressure located over southern Kansas/northern
Oklahoma with its attendant surface front just barely nosing into
far southwestern Missouri. Diurnal heating/destabilization this
afternoon in combination with 0-6 km shear of 30-35 kt will allow
for the potential of strong to marginally severe storms capable of
producing wind gusts up to 60 mph and quarter size hail. However,
coverage should be limited to far southwestern Missouri and
southeastern Kansas late this afternoon and evening, although
remnant outflow boundaries from this morning`s activity adds a
layer of uncertainty.

The HREF reflectivity paintball product indicates strong
agreement among ensemble members on the redevelopment of
additional widespread showers and storms across southern Missouri
tonight and continuing into Wednesday morning. Fortunately, this
activity looks to largely stay south of locations that saw the
greatest rainfall totals this morning, which should help limit the
flooding threat across the northern CWA. Generally expecting 1-2
inches of rainfall across southern Missouri through Wednesday
morning. However, there is the potential for localized pockets of
3-4 inches of rainfall. Moisture- rich air with PWATs in the
1.8-2.0" range will allow for efficient rainfall rates, and recent
short term guidance develops the axis of heaviest precipitation
parallel to the mean northwest flow aloft. This would allow for
training storms to repeatedly drop heavy rainfall over the same
locations.

Temperatures this afternoon have been quite variable across the
CWA thanks to the aforementioned surface front and cloud cover.
Highs across far southwestern Missouri and southeastern Kansas
will top out in the mid 80s, while parts of the eastern Ozarks may
not even get out of the 60s. For Wednesday, the cooler air looks
to overspread the entire region, with highs in the 70s to low 80s
CWA- wide.

.LONG TERM...(Wednesday night through Monday)
Issued at 245 PM CDT Tue Aug 16 2022

Any lingering showers look to push southeast into Arkansas
Wednesday afternoon with drier air moving in behind it. Mild and
mostly dry conditions look to persist through Thursday and Friday.
Ensemble guidance does indicate a low chance of a few showers
across central Missouri Friday afternoon as shortwave energy moves
through the region, but confidence remains low at this point.

Better rain chances do return this weekend into the early part of
next week as a low pressure system is progged to move through the
Midwest into the Great Lakes region. Also expecting below average
temperatures through this period as we remain on the eastern
periphery of the upper level ridge out west. The WPC Cluster
Analysis indicates fairly good agreement of the current pattern
persisting through at least Tuesday, with northwest flow aloft and
below average temperatures. Looking beyond, the CPC 8-14 day
outlook indicates that this pattern will continue, favoring below
normal temperatures and above normal precipitation.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 631 PM CDT Tue Aug 16 2022

Confidence is high that showers and thunderstorms will develop
close to the terminals tonight. Ceilings are expected to drop into
the MVFR and eventually the IFR categories as well, which may
persist into Wednesday morning. JLN and BBG currently have the
highest chances of storms. Winds will remain easterly to
northeasterly however they could briefly turn southeasterly
for a short time tonight. Vis and ceilings return to MVFR and
eventually VFR by Wednesday afternoon.


&&

.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&

$$

MESOSCALE...Burchfield
SHORT TERM...Didio
LONG TERM...Didio
AVIATION...Burchfield