Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 07/09/22

Area Forecast Discussion

National Weather Service North Platte NE

 600 PM CDT Fri Jul 8 2022

.SHORT TERM...(This evening through Saturday night)
Issued at 415 PM CDT Fri Jul 8 2022

The primary forecast concerns heading into the weekend are
concerning thunderstorm chances and the return to triple digit heat.
Isolated storms may work into the panhandle counties this evening,
while widespread 100s for highs are possible by Sunday.

This evening and tonight... A surface boundary anchored along the
lee of the Rockies is helping spur some thunderstorm activity well
to the west this afternoon. Steady southeast winds in the low levels
is adding moisture to the mix, along with enhanced upslope flow.
Steering winds will direct some of the activity in Wyoming toward
the southern panhandle and far southwest Neb late this evening.
However, short term guidance varies, with some solutions suggesting
the activity to hold together to reach the CWA, while others have it
fizzling out. Included a schc PoP through 06z for ares west of Hwy
61 to account for the more aggressive solutions. Thinking the
continued moisture advection and somewhat unstable mid levels with
lapse rates 7-8 C/km will be enough to support a few storms from
KIML to KGRN. Can`t rule out some strong wind gusts or perhaps hail
due to strengthening deep layer shear (up to 40 kts of 0-6km) and
almost 1000 j/kg MUCAPE around sunset. The one caveat for our
counties compared to the western panhandle (CYS cwa) would be the
farther distance from organized forcing and moisture convergence.
One other concern for the overnight period is fog. The setup does
not appear as conducive as last night due to slightly stronger winds
at the surface, a transition to southerly flow, and the chance to
dry out from Thursday`s rain. However, will need to monitor
potential stratus or fog along the eastern CWA boundary, which is
where the better moisture component exists and winds are slower to
switch from the southeast. For min temps, used a general blend which
lines up with the NBM envelope and MOS guidance, to give mid 60s.

Saturday... The large upper ridge currently centered over the Four
Corners expands into the central Plains, while the surface boundary
spreads off the higher terrain and approaches as a warm front.
Southerly return flow around the Great Lakes surface high
intensifies ahead of the front. Moisture advection at the low levels
becomes negligible and dry air from the mid levels arrives, which
should result in fair conditions. One item of note is a subtle
shortwave riding up and over the main ridge. This feature combined
with steep low/mid level lapse rates may be enough to support a very
isolated shower or storm. For now, kept PoP out of the forecast.
Opted to use the warmer end of guidance for max temps, especially
with H85 temps warming 4-5 C over today`s values. Forecast max temps
range from near 90F in central Neb to the lower 100s in the
panhandle.

.LONG TERM...(Sunday through Friday)
Issued at 415 PM CDT Fri Jul 8 2022

The anomalous upper ridge spreads further onto the Plains on Sunday
as the surface warm front crosses the Sandhills. Southwest flow at
H85 pushes temps to around 30C in the west and 27C east. With
generally fair conditions to start the day, these values should
translate to widespread highs in the lower 100s. Again sided with
the warmer end of guidance for forecast max temps, which sits toward
the 75%ile of NBM envelope and above most MOS solutions. Heat index
values still meet the guidelines for the eastern half of the CWA, so
potential is high for a future headline. The ridge begins to break
down late in the day and is accompanied by a stout mid-level
shortwave. These factors, along with a surface cold front, present a
formidable chance of precipitation Sunday evening and night. The
environment is rich with instability and deep layer shear along and
ahead of the front. Potential exists for strong or severe storms,
particularly toward central Nebraska. A brief reprieve from the
extreme heat is in store to start the new workweek, and periodic
precipitation chances remain with northwest flow aloft. Mid to late
week, the ridge rebuilds over the Plains. Long range guidance
suggests a more stubborn ridge this time, owing to an extended heat
wave heading into next weekend. With precipitation chances looking
scant past Tuesday and possibly several days around the century mark
for highs, will need to check on fire weather conditions.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 600 PM CDT Fri Jul 8 2022

VFR conditions expected at TAF sites thorugh the valid period.
Isolated thunderstorms upstream over the Black Hills and entering
the Nebraska panhandle are expected to diminish rapidly this
evening with no impact expected at TAF sites. A bloom of
fog/stratus will start to push in from the east toward daybreak
but probabilistic guidance indicates little impact west of
highway 183 so will keep TAF sites VFR and see if trends in later
guidance indicate a need to mention in TAFs.

Winds will generally be light overnight with little impact to
aircraft operations. However the low level wind field will amplify
tomorrow and a low level jet will develop Saturday night. This
will create some gusty conditions after daybreak on Saturday with
gusts continuing beyond the end of the valid period.

&&

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

$$

SHORT TERM...Snively
LONG TERM...Snively
AVIATION...MBS



Area Forecast Discussion

National Weather Service Phoenix AZ

 511 PM MST Fri Jul 8 2022

.UPDATE...Updated Aviation Weather Discussion.

&&

.SYNOPSIS...
Dry conditions will persist across the lower deserts the
remainder of the week with isolated showers and storms returning
to eastern Arizona tomorrow. Temperatures will continue to warm
with many lower elevation communities reaching 110 degrees
starting today. These above normal readings should last through at
least the middle of next week. As moisture seeps back into the
region next week, mountain storms should become more expansive
with impacts gradually working back into lower elevations.

&&

.DISCUSSION...
A broad area of high pressure remains centered across the southern
Great Plains, extending westward over the Desert Southwest. In
the short term, dry southwesterly flow continues, leading to
nearly cloud free conditions across the area once again. PWAT has
climbed slightly since yesterday to around 0.75", but the lower
atmosphere still remains quite dry. In terms of the short term
heat, ACARS profiles show H5 heights of near 594dm at the moment,
with H5 heights near 597dm expected by this evening. H8
temperatures will reach 30C today, and with full insolation during
peak heating, the odds of reaching 110F grows to better than 50%
for most lower elevation communities.

Over the next 24 hours the upper level high will continue to
strengthen and shift westward over the area, which will allow for
even warmer conditions to develop, but will also turn the mean
wind for much of the lower atmosphere to the southeast, which
will increase moisture content. In fact, there is good evidence of
a notable theta-e surge through eastern AZ Friday night setting
the stage for enhanced deep convection Saturday afternoon into
Gila County. In addition to the improved wind profile and moisture
advection, a weak PV anomaly will increase lift on Saturday
afternoon or evening with thunderstorms quite possible over Gila
County. Precipitation is not expected to be significant, but NBM
does show a 40-50% chance of at least measurable precipitation in
Gila County with a less than 10% chance elsewhere. The HREF shows
a 90% probability of winds in excess of 30 kts there, with a
10-20% chance over the valleys. Considering the inverted-V
profile, gusty outflow winds conceptually make sense in this
pattern, with a low chance of these winds reaching the Phoenix
metro area. Scattered higher terrain thunderstorms will likely
occur each afternoon into early next week with little to no
activity in the valleys.

Aside from thunderstorm potential and impacts, heat will be the
other main weather story through next week. Consolidated H5
heights in excess of 595dm are still forecast to drift around the
four corner much of next week representing levels near the
climatological 99th percentile. Thermal profiles in the H8-H7
layer are still not exhibiting a direct trend peaking only around
the 90th percentile with EFI surface temperature values similarly
elevated at around 0.6 to 0.7, but not particularly unusual. At
this time, H8 temperatures are forecast to be warmest Monday (31C-
32C) yielding the best potential to reach Excessive Heat
thresholds. Accordingly, an Excessive Heat Warning remains in
effect for Monday for much of the lower deserts. Improving
moisture profiles and influence of outflows should temper daily
highs somewhat beyond Monday and preclude more than isolated
instances of high HeatRisk with NBM probabilities of reaching
criteria dropping well below 10%.

By the middle of next week ensemble guidance remains in good
agreement that the high pressure system will migrate northward
allowing more favorable moisture advection and instability profiles.
Model evidence also points towards at least one day with direct
influence from an easterly wave and heightened shear profiles.
NBM POPs across lower elevations begins to increase into a 15-25%
range during the middle of the week which seems reasonable given
the overall model uncertainty and lead time. With that said,
there are many hints that moisture profiles will become ample by
Wednesday yielding the next very active day with storms descending
into lower elevations with wind and dust impacts. The various
ensemble systems all generally agree on this idea.

&&

.AVIATION...Updated at 0000Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Somewhat gusty winds will continue with gusts near 17-23 kt
through the early evening. Drainage easterly winds will return
later than normal overnight around 11Z. Few to scattered cloud
decks mainly aoa 15 kft through the period. Distant storms may
cause outflow winds from the east/southeast Sat evening along with
weakening sprinkles short of vcsh. An earlier wind shift Sat
evening due to this east and additional cloud cover is more likely.
Blowing dust would be most likely at KIWA.

Southeast California/Southwest Arizona including KIPL and KBLH:
Some gusty evening W sundowner winds to develop at KIPL this
evening and slowly diminish overnight. Breezy S-SW winds this
evening at KBLH will also diminish. Otherwise, diurnal winds and
mostly clear skies will prevail at KIPL/KBLH.

&&

.FIRE WEATHER...
Thunderstorms will gradually return to the eastern districts by
Saturday, with coverage and wetting rainfall chances generally
increasing and expanding westward through next week. Minimum
afternoon humidity levels will mostly fall into the teens, however
higher terrain locations of eastern districts should see humidity
values closer to a 20-30% range next week as moisture returns.
Overnight recovery will be mostly poor to fair in a 20-50% range
though improvement becomes more likely beyond the middle of next
week as thunderstorm chances expand. Some enhanced upslope
afternoon breeziness will be common, but the greater wind concerns
will become larger and stronger outflow boundaries traveling
extended distance from storms starting this weekend.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning from 10 AM to 8 PM MST Monday for
     AZZ530>544-546-548>551-553>555-559.

CA...Excessive Heat Warning from 10 AM to 8 PM PDT Monday for
     CAZ563>570.

&&

$$

DISCUSSION...Hodges/18
AVIATION...Sawtelle/Feldkircher
FIRE WEATHER...Hodges/18