Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 05/06/22

Area Forecast Discussion

National Weather Service North Platte NE

 605 AM CDT Thu May 5 2022

.SHORT TERM...(Today through Friday)
Issued at 345 AM CDT Thu May 5 2022

The main concern in short term is with fog and precipitation
chances. Light winds overnight have led to areas of patchy fog,
however widespread fog is not expected, thus no headlines have been
issued, but expect patchy fog to linger through the morning hours.

As for precipitation, several models have been trending drier
across north central Nebraska today, thus decided to lower pops
across north central as with recent trends precipitation has
already decreased this morning. Although wrap around moisture may
still occur as the sfc low continues to track northeast. The best
PoP chances look to be across our southeastern and eastern
forecast area and into central and eastern Nebraska. Any
precipitation that does develop will be showery in nature and
scattered.

.LONG TERM...(Friday night through Wednesday)
Issued at 345 AM CDT Thu May 5 2022

An active weather pattern continues in the long term with several
systems bringing shower and thunderstorm chances. A shortwave trof
moves into the High Plains on Saturday and becomes the focus for
thunderstorm development. Gusty southerly winds will help to bring
sufficient moisture to the area, along with CAPE values around
1000 to 1500 J/kg should provide a favorable environment for some
severe storm potential across much of our forecast area. Another
system also tracks into the area mid-week bringing precipitation
chances on Wednesday afternoon and evening.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 605 AM CDT Thu May 5 2022

Expect a tight gradient in flight conditions across Nebraska this
TAF period with IFR/MVFR southeast to MVFR/VFR northwest. Will go
on the pessimistic side of things and opt for the lower
categories as predominate instead of chasing cats with tempo
groups and amend as/if needed. Expect KVTN will remain just
outside of precipitation so VCSH should be adequate with MVFR
cigs until this afternoon, then trend to VFR. KLBF looks to remain
in IFR cigs with showers into this afternoon, then a trend
through MVFR to VFR by this evening.

After some clearing this evening, fog/stratus will begin to form
in eastern Nebraska where boundary layer moisture is better and
start building back westward. Expect best chance for stratus and
fog will be just east of TAF sites but will mention some fog in a
tempo toward the end of the valid period in case cig/obvis
overperforms.

Winds will generally be light with little impact to aircraft
operations.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...Gomez
LONG TERM...Gomez
AVIATION...MBS



Area Forecast Discussion

National Weather Service Chicago/Romeoville, IL

 646 AM CDT Thu May 5 2022

.SHORT TERM...
Issued at 327 AM CDT Thu May 5 2022

Through Saturday...

The rest of the week forecast centers on the next bout of clouds,
rain, and cool conditions, which we have had our fair share of
this spring. Key messages with this upcoming event are:

* Showers to gradually increase in this afternoon with I-80 and
  south more favored

* Maximum rain footprint and overall regional intensity looks to
  be during the day Friday, including some thunderstorm potential
  mainly along/south of I-80, where rainfall amounts over an inch
  are most favored including a stripe or two of 1.5"+.

* This continues to not resemble a widespread high impact event,
  with hydrologic concerns mainly tied to a handful of river
  points that may climb to minor flood stage, though some field
  and poor drainage minor flooding is probable, mainly on Friday

Satellite water vapor ABIs early this morning show the closed low
entering western Kansas with its moist conveyor belt ahead and
multiple areas of convection embedded within this across Missouri
to Oklahoma. Models are in a little more sound agreement on this
headed due east throughout today and this evening, which would
keep well-established east-northeast lower tropospheric flow over
the CWA. This coupled with a few dry layers between 700 and 850 mb
as sampled by last evening`s RAOBs and a couple early morning
aircraft soundings support a slightly slower onset of rain today,
especially north of I-80. Meanwhile south of I-80, indications are
that a lead impulse, possibly convectively-enhanced, will track
east-northeast from the Ozarks region at present and across
central Illinois this afternoon. Ahead of this, a compact area of
enhanced isentropic lift and moisture transport should support
increased shower coverage during midday that will shift northeast
through early evening. The overall cloudy and easterly wind setup
today supports highs only in the upper 50s to possibly lower 60s,
with continued only around 50 near the lake.

As the upper low moves into eastern Kansas to Missouri tonight,
confidence in shower footprint morphology starts to diminish,
owing in part to model spread as well as just the evolution of
spokes of forcing around a closed circulation. Model solutions
have come into more agreement with the idea of less rain north
and more central/south into Friday, with a gradient (possibly
tight) of rainfall amounts in/close to the northern CWA. Prior to
that though, there certainly could be some breaks/lulls in shower
activity tonight, and the far north toward the Wisconsin state-
line including Rockford may struggle to see anything but lighter
shower activity. "Periods of showers" is the best descriptor of
forecast evolution for tonight, while all out "rain" may be best
for central/south on Friday.

To elaborate more on Friday, this is the period where the system
moist conveyor belt and trough of warm air aloft (TROWAL) noses
over the CWA being north of this closed low. This is in tandem
with an upper jet nose of 85+ kt curling around the low center
with its left exit over the area and developing system
deformation. An associated more solid area of rain should set up,
with some embedded thunder possible as slightly steeper elevated
lapse rates poke in on the northern periphery of the system dry
slot. This area of rain is within modest moisture convergence
near 850 mb and renewed moisture transport at/just below the
TROWAL level. While this looks good for a steadier rain and
respectable warm cloud processes with freezing levels 11-12 kft,
absolute moisture values are not overly high (PWATs of 1.25
inches, 700 mb Tds of 1-2C). Just to the north/northeast of a
slow-moving upper low can be a "got ya" area for an isolated flash
flood event (such as the Seneca event July 12, 2021), however
typically we need higher absolute moisture values, more embedded
thunder, and an even slower system translation.

So based on this reasoning, the main impacts continue to look
like field and poor drainage flooding, as opposed to flash
flooding. Looking at ensemble hydrograph data supports a couple
river points reaching flood stage with our forecast rainfall
(QPF), but knowing isolated higher values are probable, did look
at some of the higher ensemble (95th percentile) output too. This
would favor more points reaching flood stage and even a few into
moderate stage. However, think a footprint of such higher-than-
forecast QPF would be on a smaller/isolated scale.

Rain and any embedded thunder will start to gradually ease in
coverage Friday evening and quickly overnight it appears as the
system heads eastward setting up for a drying Saturday. After a
cool Friday with temperatures 10 or even a little more degrees
below normal, Saturday should see sun and in some places beginning
first thing in the morning. Have highs in the mid 60s inland
while mid 50s lakeside.

MTF

&&

.LONG TERM...
Issued at 333 AM CDT Thu May 5 2022

Saturday night through Wednesday...

Long range models continue to show a large-scale upper ridge
building from the Gulf Coast up through the Great Lakes, as a
closed upper low moves south along the Atlantic Coast before
shifting over the southeastern states next week, setting up a Rex
Block. At the same time a deep upper trough sets up on the West
Coast. Perturbations will be riding up along the western side of
the ridge. Most of these waves appear to stay west, but there is
a possibility that one or two may skim the area and thus a chance
for showers and isolated thunderstorms, primarily in western
counties. Chances for precipitation decrease greatly as your go
east under the ridge. At this point there is a signal for
increased chances of showers and possible isolated thunderstorms
on Wednesday, but still not a very strong signal, so confidence is
certainly low on any precipitation next week at this time.

Overall southerly flow throughout the atmosphere continues to
indicate much warmer weather, especially Monday onwards. The
National Blend of Models (NBM) continues to show high
temperatures in the low to mid 80s next week, while it`s possible
to reach into the upper 80s and even around 90. Several variables
can interfere with these higher temperatures occurring, such as
cloud cover and locations of ridge axis / path of short waves and
precipitation, but the general signal remains well above normal
temperatures remains. This same overall flow will also increase
our dewpoints into the 60s, and possibly approaching 70 Tuesday
into Wednesday. Models indicate that a weak lake breeze could set
up on the Illinois shore each day (less so Tuesday), allowing
some cooler temperatures along the shore, but confidence is not
all that high at this distance. This early season warmth after
the recent cold, especially if the humid air also accompanies it,
might lead to some health concerns and will be something we`ll
have to watch.

BKL

&&

.AVIATION...
For the 12Z TAFs...

Aviation weather concerns for the 12Z TAFs:
* Light showers moving in this afternoon with MVFR ceilings, then
  rain showers becoming more common tonight into Friday
* IFR ceilings expected to develop this evening.
* Slight risk of LIFR ceilings to develop Friday morning, and a
  slight chance for thunderstorms mainly to the south.

VFR conditions with light northeasterly winds will generally prevail
throughout this morning. A low pressure system will bring showers
this afternoon, although exact timing of precipitation start
remains uncertain by a few hours. Spotty sprinkles are possible
late this morning through mid afternoon, but are not mentioned in
the TAFs due to expected minimum impacts to operations. As the
atmosphere saturates down this afternoon, expect MVFR ceilings to
develop, while continued saturation in showers will bring IFR
conditions after sunset. This is looking more likely to occur by
mid evening than with previous TAFs. The exception will be sites
further north and west (RFD), in which it looks like heavier
precipitation will stay south, so the worst case conditions
expected are MVFR ceilings.

Showers are expected to become more steady Friday morning, so we
bring in an overcast IFR ceiling with slightly lower visibilities.
These IFR conditions are expected to remain through the end of
the TAF period. There is a chance for even LIFR ceilings, but
trying to forecast that onset is difficult. Additionally, there is
a chance for thunderstorms on Friday. The main area of focus will
be south of the terminals, and therefore are not in the TAFs, but
situational awareness of this possibility should be maintained.

BKL

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&

$$

Visit us at weather.gov/chicago

Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/NWSChicago
www.twitter.com/NWSChicago
www.youtube.com/NWSChicago



Area Forecast Discussion

National Weather Service Phoenix AZ

 453 PM MST Thu May 5 2022

.UPDATE...Updated 00Z Aviation Discussion.

&&

.SYNOPSIS...
High pressure will strengthen over the region through Saturday
allowing temperatures to gradually warm to around 10 degrees
above the seasonal average with lower elevation communities
likely reaching 100 degrees by Friday. Seasonably dry conditions
will also continue with no rain in sight. A large, but dry,
weather system will begin to impact the region over the weekend
resulting in increased winds and eventually cooler temperatures
going into early next week. Below normal temperatures will be
possible for a good portion of next week.

&&

.DISCUSSION...
A warm and very dry airmass remains in place across Arizona as an
upper level high continues to strengthen today. ACARS soundings
show a subsidence inversion aloft lowering in response to the
strengthening high pressure. ACARS soundings reveal that the current
PWAT is a paltry 0.25" for the Phoenix area. Unsurprisingly, the
entire state of Arizona is nearly cloud free at this time. As
this ridge continues to settle into the region today it will boost
daytime highs to near 100 degrees across the western deserts and
to the mid 90s across south- central Arizona.

Upper level heights will continue to rise, eventually peaking at
around 586-587dm on Friday. The higher thicknesses will give us
our hottest days so far this year on Friday and Saturday, with
NBM guidance showing lower desert highs between 98-102 degrees.
These readings will be around 10 degrees above normals, but fall
well short of records which are close to 110 degrees. With very
little spread in the NBM temperature percentiles, confidence is
very high in this forecast.

A pattern realignment will also begin to take place on Friday and
Saturday as a longwave trough rapidly deepens to our northwest,
resulting in increased height packing aloft across our region.
Even though the trough will still be well to our north this
weekend, keeping us under a warm air mass, the tighter height
gradient will promote breezy to windy conditions. Wind gusts
Saturday afternoon are likely to increase to 20-30 mph for most
areas, to as high as 30-40 mph across Imperial County. Guidance
shows winds are likely to peak on Sunday with advisory level winds
possible across Imperial County and gusts elsewhere more in a
25-35 mph range. EFI values reach 0.6 to 0.8 for this period so it
will be unusually windy, but not exceptionally so.

A large scale blocking pattern will fully take shape over North
America starting early next week with an expansive and deep trough
setting up across the Western U.S., and a cut-off low developing
along the East Coast. WPC clusters show high confidence in this
general outcome but consistent uncertainty through much of the
forecast with respect to how deep the trough will be and where
the trough axis will line up. The EPS and GEFS ensemble means are
a bit further to the south and east with the trough than the
CMCE. No matter which solution verifies, temperatures should
decrease with a corresponding increase in wind speed. If the
EPS/GEFS solution verifies these effects would be slightly
greater than with the CMCE solution. High temperatures will
definitely decline into the 90s early next week with the NBM
bottoming out near 90 F for Phoenix Monday-Thursday. As of right
now, Thursday has a 55 percent chance of failing to reach 90 F in
Phoenix. By late next week this trough will move inland, but will
probably be filling in by that time reducing any chance of rain
to essentially zero.

&&

.AVIATION...Updated at 2350Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation concerns expected through the period. Westerly winds
below 10 kts will prevail through the evening hours, becoming
easterly after 04-05z. A switch back to westerly expected after
20-21z Friday afternoon with speeds remaining at less than 10 kts.
Skies will remain mostly clear through the period.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation concerns expected through the period. Winds will
generally remain below 10 kts and follow a diurnal pattern tonight
into Friday morning. Winds will then pick up out of the south to southwest
Friday afternoon with gusts up to 20-25 kts. Some passing high-
level clouds above 20 kft will move through the area this evening
through the overnight hours.

&&

.FIRE WEATHER...
Dry weather with above normal temperatures will continue through
the weekend. Typical afternoon upslope breeziness will be common
with gusts generally less than 20 mph through Friday. By the
weekend into early next week, winds are expected to increase with
daytime gusts more commonly in a 20-35 mph range, locally higher.
Minimum afternoon humidity levels will be reduced into the single
digits each day through at least the weekend, while overnight
recovery mostly top out in a 15-30% range through this weekend and
just a tad bit higher early next week. The higher winds Saturday-
Monday are likely to bring brief periods of elevated fire weather
conditions as humidities remain quite low over the entire region,
especially for southeast California and southern Gila County.

&&

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

$$

Visit us on Facebook, Twitter, and at weather.gov/phoenix

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