Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/07/21

AREA FORECAST DISCUSSION

National Weather Service Albany NY

 1045 PM EDT Mon Sep 6 2021

.SYNOPSIS...
High pressure will bring generally fair weather, and near
seasonable temperatures tonight through Tuesday night. A strong
frontal system will approach from the west later Wednesday,
bringing showers and thunderstorms Wednesday afternoon and
night, with some locally heavy downpours possible.

&&

.NEAR TERM /THROUGH TUESDAY NIGHT/...
As of 10:30 PM EDT, winds continue to weaken tonight which
should allow the boundary layer to decouple over the coming
hours. Temperatures have cooled down a bit quicker than the
forecast showed so we adjusted temperatures downward a few
degrees to account for the latest trends. A few isolated showers
associated with a pressure trough and the incoming upper level
disturbance/cold pool are moving off Lake Ontario and through
the Adirondacks. These showers/sprinkles are weakening and will
likely diminish before reaching our western Mohawk Valley or
southern Adirondack areas. The high res NAM seems too aggressive
in allowing showers to extend far inland into our area but the
HRRR seems more reasonable so we leaned closer to that drier
solution. Given some sprinkles tracking towards far southern
Herkimer County off Lake Ontario, we introduced some slight
chance POPs there which lined with BGM but otherwise, maintained
a dry forecast.

Patchy fog should then develop mainly after 06 UTC in prone
valley areas as the temperatures close in on the dew points
which will be in the low 50s. Since we did not rain in the
evening like we did yesterday and winds will be elevated for the
first half of the night, fog should not become as dense or
widespread as last night. Thus, we limited it to valley areas.
Still expecting overnight lows to turn chilly and based on
current trends, we decreased our lows a few degrees and we now
forecast lows to reach into the low 50s with upper 40s in the
southern Adirondacks and southerns Greens.

Previous discussion...

Tuesday...Heights continue to rise aloft, and we will end up
under the axis of an amplifying upper-level ridge tomorrow
afternoon. This will help keep tranquil weather for our region
during the day tomorrow. Meanwhile, the surface high will slide
to our southeast during the day, which will result in
northwesterly winds and cold air advection early in the day
switching to southwesterly winds and warm air advection tomorrow
afternoon. After a cool start to the day, high temperatures
will recover to the mid and upper 70s for valley locations,
although higher elevations will only have highs in the 60s.

Tuesday Night...Looking aloft, the upper-level ridge axis will
depart to our east as an impressive closed upper low digs south from
Ontario towards the Great Lakes Tuesday night. A surface low is
expected to develop in response to the upper low and track north of
the Great Lakes. As this low deepens to 992 mb by Wednesday
morning, it will drag a strong cold front towards our region.
Therefore, even though the best upper forcing (cyclonic vorticity
advection, height falls) will remain to our west through much of the
nigh, a few showers will be possible towards daybreak for our
far northwestern areas ahead of the approaching front. In the
lower levels...as the surface high slides further to the east, warm
air advection into the region continues, with a warm front expected
to lift through the region overnight. Behind this warm front,
advection of higher theta e air into the region will continue, with
PWAT values rising to around 1.2-1.3" by Wednesday morning. The
combination of warm air advection, higher dewpoints, and more cloud
cover than the previous night will result in warmer overnight lows,
with mid 50s expected in the high terrain and upper 50s to around 60
for valley locations.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
A cold front will slowly approach from the west later Wednesday
into Wednesday night. Strong south/southwest flow will develop,
especially within the mid and upper levels of the atmosphere. As
the front tracks east, it should tend to slow down a bit,
especially as ridging off the New England coast potentially
builds a bit stronger, while Hurricane Larry tracks into the
northwest Atlantic Ocean. PWAT`s are forecast to increase to
1.5-1.75 inches across eastern New York/western New England, and
with winds becoming nearly parallel through a deep portion of
the troposphere, the potential for training
showers/thunderstorms with locally heavy rainfall exists for
late Wednesday afternoon into at least the first half of
Wednesday night. The best chance for heavier downpours currently
appears to be the region from the northeast Catskills, Capital
Region into southern VT, however this could change.

There could be some embedded thunderstorms as well, although the
coverage of stronger thunderstorms will be modulated by timing
of frontal passage, which may not occur until after sunset in
some areas. However, mid level wind fields will be strong, with
H500 winds of 40-50 KT, so strong wind gusts could occur within
any bowing line segments.

Even outside convection, some strong south winds may occur ahead
of the front, perhaps gusting 25-35 mph within some north/south
oriented valleys, including portions of the Hudson River Valley
close to the Capital Region.

As for temperatures, some morning breaks of sun and warm temps
aloft should allow max temps to reach 75-80 in most valley
areas, with upper 60s to lower 70s across higher elevations.
Lows Wednesday night mainly in the mid 50s to lower 60s.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
A mostly quiescent weather pattern can be anticipated during the
long-term forecast period. The large-scale upper level pattern
during this period will still undergo a transition from a more
amplified (warm West U.S. vs. a cooler East U.S.) configuration to
start the period to a more zonal/semi-zonal setup later on in the
extended. This transition will contribute to some of the uncertainty
in the weather pattern later in the extended. The weather pattern
will remain progressive too through the extended. As far as
temperatures, we`re expecting to see a cooler than normal bias in
anomalies with things feeling more Autumn-like over the region
during this period.

We start off the long-term period Thursday with eastern New York and
western New England on the backside (cold-side) of a pretty potent
storm system that will be centered well off to our north near the
Hudson Bay and it`s associated cold front to our east just off the
coast of New England. Cooler and drier conditions will be in place
as cold air advection (CAA) ensues. Thermodynamics between Lake
Ontario and the air just above it plus several mid-upper level
impulses overhead associated with an upper level trough/broad-
cyclonic flow aloft will be supportive of some lake-enhanced rain
showers over parts of the area as backing winds out of the west
flows downwind of Lake Ontario. Additionally, there could also be
areas of orographic enhancement during the diurnal peak hours on
Thursday. Lake-enhanced and any diurnal-orographically driven rain
showers should wane during the evening/nighttime hours due to the
loss of energy from the sunlight and westerly winds subsiding.

On Friday, a broad 1016 hpa surface high pressure system is progged
to build into the region from the west-southwest. This will
effectively result in dry and tranquil conditions returning to the
ALY forecast area. Expect a mostly sunny to partly cloudy day with
areas south of Albany seeing the clearer conditions due to its
proximity to the aforementioned high pressure system building in.

On Saturday, expect a sunny to mostly sunny day as the high pressure
system gets a firmer grip over the region with the center of the
1020 hpa high over the Mid-Atlantic states into the Carolinas.

For Sunday, forecast models are advertising a powerhouse storm
system that`s currently forecast to track from the Northern
Plains/Upper Midwest Region northeastward into Ontario and
eventually Quebec. It`s uncertain this far out as to how much
influence weatherwise this storm system will have over our area.
Current thinking is that clouds will increase during the day on
Sunday especially over our northwestern zones (Herkimer and Hamilton
Counties). Most areas at this point will remain dry with the
exception of Herkimer and Hamilton Counties. Will have to continue
to monitor trends on how much extent and thus influence this storm
system will have on the area. For now, have just low-grade PoPs for
areas northwest of Albany with the 30% PoPs over Herkimer and
Hamilton Counties.

Dry and tranquil conditions return to the area to start the new
workweek, should we have any precipitation over the area on Sunday.
The passage of a cold front associated with the aforementioned storm
system will result in cooler, more Fall-like temperatures on Monday.

With the exception of Sunday, high temperatures will hover in the
lower 70s along the river valleys (60s and even some upper 50s in
the higher elevations). On Sunday, high temperatures will top out in
the mid 70s along the river valleys (60s higher elevations).
Overnight low temperatures during this period will be mostly in the
50s (40s higher elevations) with the exception of Sunday night where
lows are progged to be in the upper 50s to lower 60s along the river
valleys (mid 50s higher elevations).

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
VFR conditions in place this evening will continue through at
least 06 UTC. Then, radiational cooling and calming winds should
allow patchy fog to develop, mainly at GFL and PSF. This could
result in IFR visibilities and ceilings. Since winds will be a
bit elevated through the first half of the night and we did not
experience rain this evening, we kept ALB and POU VFR where
there is low confidence that fog will develop. Any fog should
lift by 13 - 14 UTC. Some guidance hints that the fog will lift
into a stratocumulus deck resulting in MVFR ceilings at GFL and
PSF but due to low confidence, we did not include this
potential. Otherwise, VFR conditions are expected through the
rest of the TAF cycle with daytime heating resulting in diurnal
fair weather cumulus clouds.

Westerly winds this evening ranging 5 to 9kts should gradually
decrease this evening, becoming light to calm after midnight.
Then, once we reach peak heating tomorrow morning by 14 - 15
UTC, westerly winds should increase towards 5 - 8 kts.

Outlook...

Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: High Operational Impact. Breezy. Definite SHRA...TSRA.
Wednesday Night: High Operational Impact. Definite SHRA...TSRA.
Thursday: Moderate Operational Impact. Chance of SHRA.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: No Operational Impact. NO SIG WX.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.

&&

.FIRE WEATHER...
High pressure will bring generally fair weather, and near
seasonable temperatures tonight through Tuesday night. A strong
frontal system will approach from the west later Wednesday,
bringing showers and thunderstorms Wednesday afternoon and
night, with some locally heavy downpours possible.

RH values will increase to 90-100 percent tonight with areas of
dew formation likely. RH should drop to 45-55 percent Tuesday
afternoon.

Gusty west to northwest winds of 15-25 mph should diminish to
less than 5 mph after midnight, then become west to southwest at
5-15 mph on Tuesday.

&&

.HYDROLOGY...
Mainly dry conditions are expected tonight through Tuesday
night.

More showers and thunderstorms are possible for Wednesday
afternoon and night. Thunderstorms could produce locally heavy
rain, resulting in ponding of water on roadways and standing
water in low lying areas. However, river flooding is not
expected at this time.

For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.

&&

$$
SYNOPSIS...KL
NEAR TERM...Main/Speciale
SHORT TERM...KL
LONG TERM...Evbuoma
AVIATION...Speciale
FIRE WEATHER...KL/NAS
HYDROLOGY...KL/NAS



Area Forecast Discussion

National Weather Service Denver/Boulder CO

 854 PM MDT Mon Sep 6 2021

.UPDATE...
Issued at 853 PM MDT Mon Sep 6 2021

Only some cirrus clouds were tracking south into the forecast area
this evening. Otherwise a very dry and mild airmass remained in
place. Surface analysis showed a couple surges moving south across
Wyoming and Montana, the first which is weakening. The main front
should arrive by/shortly after daybreak resulting in about 8-9
degrees of cooling (but still above normal temperatures) across
northeast Colorado Tuesday. Satellite imagery from earlier this
evening showed a plume of smoke shifting this way behind the
front, so we do expect an increase for tomorrow and will mention
areas of smoke in the forecast.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 220 PM MDT Mon Sep 6 2021

The strong upper level high will remain over the Great Basin and
only shift slightly eastward through Tuesday. Weak northwest flow
around the high will continue to bring warm and dry conditions to
the Central Rockies. It will be a cool night in the low lying
areas again due to the dry airmass and light winds. An upper level
trough will pass well north of Colorado and over the Northern
Plains. A weak cold front associated with this system will push
south through Colorado tonight and bring slightly cooler
temperatures for Tuesday. Highs across northeast Colorado will be
about 4-7F cooler than today. This will put highs in the mid to
upper 80s. Looking at satellite and the HRRR model, appears smoke
will increase over the region tonight and Tuesday. This may
limited afternoon heating by a couple of degrees.

.LONG TERM...(Tuesday night through Monday)
Issued at 220 PM MDT Mon Sep 6 2021

Hot and dry is the main headline for the period. There is good
consensus among ensemble and deterministic guidance that an upper
level ridge slowly progresses eastward over the region through
the week. This will promote unseasonably warm temperatures and dry
conditions. The mentioned conditions will increase fire weather
concerns; however, winds may likely keep us below criteria for
red flag headlines.

An upper level ridge will dominate the pattern for much of this
week. Weds., the main axis remains to the west and gradually moves
eastward. This will support below normal moisture and unseasonably
warm temperatures. Temperatures trend warmer into Thurs. marked
by a bump in 700mb temperatures. There is increasing potential for
the Denver area to break records Thurs/Fri (94/93) with highs
forecasted to be in the mid to upper 90s. Slightly cooler
temperatures expected for the weekend in the low 90s at the lower
elevations and 70s over the higher elevations. In regards to
moisture this week, relative humidities drop into the teens in
many areas through Fri. increasing fire weather concerns. Weaker
winds will help keep conditions below red flag criteria. Ensemble
guidance shows the jet max to stay north of the region which will
limit high wind potential. Fri/Sat afternoon may warrant
monitoring as ensemble guidance has members with gusts above 20
mph over parts of North Park, but confidence is not high at this
time.

Deterministic guidance continues to show potential for the passage
of a few embedded shortwave troughs in the NW flow aloft this
weekend. Details still remain uncertain with differing solutions,
but general consensus exhibits them to be fairly weak. A signal for
gradual moisture return combined with weak QG forcing for ascent
will bring back chances for afternoon showers and thunderstorms
Sat/Sun over the higher terrain. Limited instability and average
precipitable water amounts should keep coverage scattered. May see
increased winds over the higher terrain Monday with increased
WNW flow aloft.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 853 PM MDT Mon Sep 6 2021

Winds should transition to light southwesterlies around 5-10 knots
overnight, and then turn northerly around daybreak Tuesday with
passage of a weak front. Smoke will likely increase behind the
front, with limited slant range visibility for the Denver area TAF
sites limiting visual approaches. We`ll go with P6SM but some
smoke (FU) in the TAFs to account for that.

&&

.HYDROLOGY...
Issued at 220 PM MDT Mon Sep 6 2021

Hot and dry conditions will limit flash flood potential for much
of the week. Moisture gradually increases over the weekend
resulting in scattered showers and thunderstorms over the higher
terrain. Instability appears to be limited and precipitable water
values are closer to average which will keep flash flood potential
low.

&&

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

$$

UPDATE...Barjenbruch
SHORT TERM...Meier
LONG TERM...Mensch
AVIATION...Barjenbruch
HYDROLOGY...Mensch



Area Forecast Discussion

National Weather Service Des Moines IA

 629 PM CDT Mon Sep 6 2021

.DISCUSSION.../Tonight through Monday/
Issued at 200 PM CDT Mon Sep 6 2021

Main Points:
- Breezy tomorrow behind passing cold front
- Cool mornings mid-week
- Dry through majority of forecast period

Not much has changed with the forecast since the overnight shift.
A shortwave trough sweeps across the northern Plains into the
Great Lakes region over the next 24 hours, which will drag a cold
front through the area Tuesday. Convection tries to fire along the
boundary, however models squash any initiation attempts due to
lack of instability and displacement of the strongest kinematic
lift to our north and east. CAA and a relatively tight pressure
gradient leads to breezy northwest winds in the wake of the
frontal passage. Pressure rises relax a bit into the afternoon
hours, but winds of 25 kts or so near the top of a well-mixed
boundary layer should keep surface winds somewhat elevated through
the day. Cooler air settles into the region as lows Wednesday and
Thursday morning possibly dip into the 40s in some areas, 50s
elsewhere. Also of of note is the HRRR smoke output suggests a
plume of wildfire smoke aloft overspreading the state late today
into tonight. Not expecting any impacts near surface or to highs
tomorrow as changing winds aloft scour out the smoke before the
peak heating hours.

Deep north/northwesterly trajectories on the eastern periphery of
a western conus ridge pushes the cold front well south toward the
Gulf region. This essentially cuts off our area from any
appreciable moisture for a while. Pattern becomes a bit more
active toward the weekend into early next as a series of
shortwaves begin to break down the western ridge, particularly
Friday night into Saturday as models bring a shortwave through the
northern Plains. Considerable timing/amplitude differences exist
in the latest deterministic model runs. GFS/EC/ECENS still favor a
dry solution with all precip displaced to our north, while the
GEFS output is more split on precip chances for the state. Favored
the dry NBM forecast for now given the scant moisture
availability and fairly progressive flow.

&&

.AVIATION.../For the 00Z TAFS through 00Z Tuesday evening/
Issued at 629 PM CDT Mon Sep 6 2021

VFR conditions are forecast through the period, with few clouds
and no precipitation or obscurations expected. LLWS of 35-40 KT is
expected during the overnight/early morning hours, but will
diminish as surface winds increase after sunrise Tuesday. A front
will then sweep from northwest to southeast across the area from
late Tuesday morning into the early afternoon, with winds shifting
from SW to NW as the front passes and becoming brisk and gusty
during the afternoon hours.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

DISCUSSION...Martin
AVIATION...Lee



Area Forecast Discussion

National Weather Service Grand Forks ND

 928 PM CDT Mon Sep 6 2021

.UPDATE...
Issued at 928 PM CDT Mon Sep 6 2021

Storms have finally started to strengthen along and behind the
cold front pushing into eastern and southern regions of the CWA.
The strongest storms have been along the surface front in Beltrami
county, where storms have taken off in 1000 J/kg of MUCAPE and
very strong effective bulk shear. Storms further west behind the
front across central portions of the CWA have also strengthened
as the main shortwave rotates into the area. CAMs have the
strongest cells moving quickly east of our CWA during the next few
hours, and that seems reasonable given the quick movement of the
shortwave and cold front. Still could see an isolated elevated
storm producing some hail through midnight.

UPDATE Issued at 650 PM CDT Mon Sep 6 2021

Will continue to monitor for any thunderstorm development in
northwestern MN as the shortwave comes in and encounters elevated
instability. HRRR and some of the other CAMs have been showing
some stronger cells developing around 01 or 02Z, and there is
still some MUCAPE over 1000 J/kg and plenty of shear to work
with, so not ruling out a few isolated strong to severe storms
just yet. Kept POPs pretty close to what we had going. Some decent
showers along the 700mb frontogensis zone in our northern
counties, so some spots are finally seeing a bit of rain reaching
the ground instead of just virga.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 337 PM CDT Mon Sep 6 2021

Isolated severe thunderstorms remain possible this evening with
better chances possibly shifting southeast along/southeast of the
Highway 2 corridor.

Showers are beginning to spread into northeast ND as the shortwave
digs southeast into Manitoba. Tds are finally increasing more and mid
level lapse rates are supporting increasing elevated instability into
the 500-1000 J/KG range in our south. Winds are already shifting to
the northwest in the northern Devils Lake Basin and axis of better
instability will also likely flatten towards the eastward over the
next 3hrs and then slide southeast (based on current RAP). This lowers
confidence in strong/severe updrafts further north, but does still
allow for window for severe near the convergence zone along the
prefrontal trough axis. The last 4 runs of the HRRR and latest
SSCRAM probabilities favor stronger initiation near this region near
and southeast of Hwy 2 mainly in MN in the 8-10PM period. 12Z HREF
was already showing this shift east-southeast with UH track
probabilities of at least 35 m2/s2 in our far east during that
window. Good forcing, high shear (35-55kt effective progged by RAP),
and elevated CAPE near 1500 J/KG should be in place amd supportive
of isolated severe potential. Hail to 1" continues to be a threat
due to steep mid level lapse rates, and wind may not be as much of a
threat due to DCAPE values being progged to remain under 1000 J/KG.
High bases and strong shear do still rain some isolated severe wind
potential especially if storms cluster and track orthogonal to stronger
0-3km shear vectors (hard to anticipate at this time).

Any lingering showers/storms are timed to exit our east around
midnight tonight, and CAA then overspread our CWA through Tuesday.
Cyclonic flow and cold pool aloft could support a few showers or
weak thunderstorms near Lake of the Woods during peak heating
Tuesday otherwise dry conditions and only diurnal CU development would
be anticipated elsewhere. Unidirectional flow and increasing
pressure gradient will support windy conditions. Max winds within the
mixed layer at this time are in the 30-35kt range so while windy
current guidance isn`t as favorable for potential advisory gusts.
Highs should be lower by 10F compared to today due to CAA and mostly
locations should remain the low to mid 70s. Lows Tuesday night
should be near seasonal averages around 50.

.LONG TERM...(Wednesday through Monday)
Issued at 337 PM CDT Mon Sep 6 2021

The chance for hazardous weather is low within the long term period.
Synoptics starting the period feature a large, anomalous anticyclone
parked over the Four Corners region with upper troughing moving
through southeast CAN. This places the area firmly under northwest
flow aloft into Thu. Late in the work week, one or two shortwave
troughs travel over the crest of the anticyclone, flattening the
upper ridge in the West. Temperatures will be near to above average
with highs in the 60s to 80s, and lows in the 40s and 50s. Despite a
very dry air mass (dew pts into the mid-upper 30s) moves into ND
around Wed, chance for frost looks low at this time with influence
of the departing upper trough keeping winds elevated and driest air
shunted to the western Dakotas.

As the ridge starts to flatten towards Thu-Sat, warm temps bottled
underneath the anticyclone attempt to break east into the Great
Plains. Best chance for exceeding 80 F spreads into FA as noted by
NBM probabilities greater than 40% spreading into eastern ND, the
Red River Valley, and west-central MN during this timeframe.

The flattening ridge as a result of one or two shortwave trough
passage/s also increases chances for showers and thunderstorms
between Thu-Sat, although progressive and flat nature of the
shortwave and general lack of confidence in assoc surface features
lessens confidence in timing and coverage at this time. A general
lack of better moisture looks to prevent possibility for heavy
rainfall, with ENS, CME, and GEFS all showing less than a 10% chance
of advecting PWATs at least 1.5 inches anywhere near the FA. Strong
to severe storms are not favored at this time as well, again owing
to the lack of suggested better low level moisture despite
sufficient shear likely to be present with the shortwave and some
signal for weak instability to briefly approach the Dakotas and
Minnesota.

Getting beyond Sat, ensemble consensus continues to flatten the
Western ridge promoting more zonal flow over much of the northern
tier of the CONUS. Zonal flow typically favors progressive shortwave
trough/ridge passages which will continue low chance PoPs and near
normal temps. Confidence in details finer than this is lacking as
timing and amplitude of such features remain outside of the
predictability horizon.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 650 PM CDT Mon Sep 6 2021

Convection and winds will be the main aviation concerns with all
ceilings VFR and no restrictions to vis. There could be an
isolated thunderstorm developing over northwestern MN in the next
few hours that could get close to KBJI, but uncertainty still too
high for more than VCTS mention. Other sites will just see some
light showers. Winds have already shifted to the north for all but
KBJI and KFAR, and the front coming in will cause the remaining
airports to shift north before 06Z. Some gusts above 15 kts this
evening, but should be settling down later tonight. Winds will
pick back up out of the northwest tomorrow, with some locations
gusting close to 30 kts in the afternoon.


&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$

UPDATE...JR
SHORT TERM...DJR
LONG TERM...CJ
AVIATION...JR



AREA FORECAST DISCUSSION

National Weather Service Hastings NE

 712 PM CDT Mon Sep 6 2021

...AVIATION UPDATE...

.DISCUSSION...(This evening through Monday)
Issued at 315 PM CDT Mon Sep 6 2021

Quiet weather continues this afternoon with clear skies across the
region. Today may very well be the warmest day of the week with
temps on track to reach into the lower 90s most places, with a few
mid 90s across Kansas. Winds are fairly steady out of the south at
around 10 kts. Late overnight tonight a dry cold front will push
through the area, swinging winds around to the north. This front
will also make for rather breezy and cooler conditions tomorrow.
Highs tomorrow are expected to be around 10 degrees cooler than
today, with south central Nebraska highs around 80 and north central
Kansas highs around 85. Winds will also pick up quite a bit with
sustained speeds around 15-20 kts and gusts around 25-30 kts at
times.

The prominent and dominating feature of the forecast is the large
upper level high pressure over the western CONUS. This high will
keep us in northwest flow aloft till the weekend. This is not great
news for smoke haze in the upper levels, with the HRRR Smoke already
indicating an increase in upper level smoke for tomorrow (and likely
the rest of the week as well). The high will then slowly meander
southeast to be centered over the Four Corners region by Thursday.
This shift will bring warmer temperatures to the midlevels and
subsequently at the surface. Temperatures are expected to warm on
Thursday and Friday, with Friday`s highs possibly rivaling today`s.
Thursday could also be a sneaky breezy day (if you believe the NAM)
as the sfc pressure gradient tightens and we sit wedged between a
lee trof to the west and high pressure to the east and southeast.

Heading into this weekend a series of shortwaves aloft work to
flatten out the high as it continues to move east and transitions us
to more zonal flow aloft. Saturday morning another cold front moves
through attached to a low centered over the northern Great Lakes.
Currently there are some minor discrepancies between the GFS and
the EC during the extended periods. One of these is the strength
of the front on Saturday morning, where the GFS shows a stronger
front, but both models keep things dry. Currently in the official
forecast temps come down only a few degrees (still maintaining mid
to upper 80s in NE and lower 90s in KS). Another discrepancy is
with Sunday morning. The EC shows a minor embedded shortwave
moving through and bringing a quick round of morning showers to
northern portions of the CWA. The GFS on the other hand keeps
things dry Sunday morning. Right now the official forecast is dry
for the entire 7 days, but this will bear watching for changes in
the weekend forecast in particular.



&&

.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 704 PM CDT Mon Sep 6 2021

Significant weather: Brief LLWS with strong frontal passage

First 6 hours: VFR with S-SSW wind 5-10kt. Confidence: High.

Rest of the period: VFR. Main concern will be timing/effects of
cold front passage at the terminals. Winds will veer to SW by
about 09Z, and continue veering to NW w/ passage of cold front in
the 11Z-13Z time frame. Immediately along/behind the front, and
before mixing depth increases, could see a brief 1-2 hr period of
LLWS around 13-14Z. Models are in good agreement showing 40-45kt
around 1K ft AGL while boundary layer remains shallow and sfc
winds are largely less than 15kt. Expect to mix into this layer by
around 15Z, resulting in gusty sfc winds that will last through
early-mid aftn. Expect a gradual decr mid to late Tue aftn.
Confidence: frontal timing - high, LLWS - medium.


&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&

$$

DISCUSSION...Shawkey
AVIATION...Thies



Area Forecast Discussion

National Weather Service Goodland KS

 504 PM MDT Mon Sep 6 2021

.SHORT TERM...(This evening through Wednesday Morning)
Issued at 151 PM MDT Mon Sep 6 2021

The forecast period begins with northwesterly flow over the area
with an amplifying ridge over the western CONUS. A dryline is setup
across the CWA with elevated to near critical fire conditions
behind. RH values less than 15% are currently being located along
and west of Highway 83 in Kansas. Winds have remained light
throughout the day (less than 10 knots) mitigating the overall fire
weather risk somewhat. Weather wise not much is occurring due to
the subsidence caused by the high pressure, as not even diurnal
cumulus have been able to form thus far. Temperatures as of 1pm
have already warmed into the upper 80s to mid 90s with a few hours
remaining of peak heating, the current high temperature forecast
remains on track of widespread 90s. The HRRR Near Surface smoke
has been showing some elevated areas of smoke moving south down
the eastern periphery of the ridge causing the potential for haze
to occur through the afternoon and into tomorrow morning, some
visibility restrictions are possible especially towards sunrise.
Overnight lows for tonight are forecasted in the mid 50s across
east Colorado to the mid 60s across eastern portion of the
forecast area.

A cold front moves through the CWA Tuesday morning as a stronger
system occludes over the Great Lakes. As the front moves through
winds will switch out of the north with gusty winds along and behind
the front, some wind gusts may approach 30-35 mph. Fire weather is
again possible due to the wind however, with RH`s not as low as
today but in the low 20s. Breezy to gusty winds will persist through
the afternoon before waning during the evening. Afternoon highs wont
be as warm as temperatures will remain in the 80s. Mainly clear
skies are expected for Tuesday night with the entire area in the
50s; some locales across east Colorado may even fall into the 40s
for a brief period of time.

.LONG TERM...(Wednesday through Monday)
Issued at 157 PM MDT Mon Sep 6 2021

The primary concern in the long term period is the potential for
near critical fire weather conditions and blowing dust resulting
from a prolonged period of hot and dry conditions combined with
breezy winds.

A large high pressure area aloft moves across the 4-corners region
on Wednesday night and Thursday and into the southern Rockies and
southern high plains on Friday and Saturday as several short wave
troughs move through the westerly flow tracking along the
U.S./Canadian border. With the somewhat chaotic pattern moving
across the northern tier of states, model solutions are showing a
wide variety of timing and location differences with the
individual short waves embedded in the flow. Suffice to say the
bulk of the dynamics associated with the embedded waves remain
north of the central high plains region through the weekend and
into the beginning of next week.

The consistencies that have remained are the slightly warmer than
average temperatures on Wednesday that warm to well above average
with highs in the lower to middle 90s on Thursday and the middle
to upper 90s on Friday ahead of a cold front that moves across the
forecast area early Saturday morning along with one of the
stronger short wave troughs aloft moving east of the Rockies and
across the northern High Plains.

Hot and dry conditions on Thursday and Friday will produce near
critical fire weather conditions across mainly the western
sections of the forecast area along and west of KS Highway 27.
Afternoon minimum relative humidity values across this area will
be in the middle teens or lower. Wind speeds are not expected to
be over 25 mph at this time, which would keep the area from
reaching critical fire weather thresholds. This will, however,
bear watching over the next few days as it will be close.

The cold front moving across the area early Saturday following
several days of hot and dry conditions will bring the potential
for blowing dust as wind speeds increase immediately along and behind
the front that could continue through mid-day on Saturday. Models
are not currently advertising windy conditions, but expect this to
change over the next couple of days. Even with the increase in
winds with the front, critical fire weather conditions are not
expected to be met on Saturday as relative humidity values will
not exceed critical thresholds due to high temperatures being
slightly cooler with readings in the upper 80s to lower 90s.

Temperatures will rise into the lower to middle 90s with an
increase in the potential to meet near critical fire weather
conditions as afternoon minimum relative humidity values venture
back into the teens.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 504 PM MDT Mon Sep 6 2021

Mainly VFR conditions expected for both terminals. Smoke aloft
could create hazy conditions that could lower visibility to around
5sm at times from 08z-14z Tuesday for KGLD, and 11z-13z Tuesday
for KMCK.

Boundary pushing thru the region will see southerly flow
currently over the area, to become northerly.

Winds for KGLD, southeast to southwest 10-20kts from 00z-08z
Tuesday, then northwest around 10kts. By 14z, north-northeast
15-30kts becoming northeast 10-15kts by 21z.

Winds for KMCK, light/variable thru 11z Tuesday, then north
10-15kts. Gusts up to 30kts from 13z-23z. By 23z, northeast
around 10kts.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&

$$

SHORT TERM...TT
LONG TERM...LOCKHART
AVIATION...JN



Area Forecast Discussion

National Weather Service Gray ME

 1043 PM EDT Mon Sep 6 2021

.SYNOPSIS...
High pressure and fair weather build in Tuesday, lasting into
Wednesday with temperatures warming into the upper 70s and low
80s by Wednesday. A slow moving cold front will approach
Wednesday afternoon bringing increasing chances of showers with
a chance of thunder late Wednesday through Thursday. Hurricane
Larry will pass well offshore this week but building long-period
swells are expected, which may result in increased rip
currents.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
1040 PM Update...No forecast changes at this time. Other than
some mountain clouds the rest of the region is clear, cool, and
dry and will continue that way overnight.

720 PM Update...Have updated the forecast mainly to clear out
the mention of thunder most everywhere. One last batch of
weakening convective showers currently near MWN will gradually
dissipate as they move eastward over the next hour or two.
Thereafter, the forecast area will be rain-free.

Previously...


Update...
Have updated the forecast based on current conditions and latest
mesoscale models. Deep convection will exit east of our forecast
area over the next hour with just isolated convection remaining
to the west. Latest HRRR does have some precipitation crossing
into northern New Hampshire from Vermont over the next couple of
hours so have upped pops for that region. Otherwise, just minor
tweaks to the near term portion of the forecast.

Prev Disc...
A trough of low pressure will exit to our east this
evening with the latest HRRR showing the precipitation shifting
east of our forecast area after 23Z. Will continue to include
enhanced wording for the possibility of gusty winds and hail in
a few of the strong storms.

Drier air will filter into the Maine and New Hampshire as winds
switch to a westerly direction tonight. However, there may
sufficient low level moisture to allow for patchy late night fog
mainly in northern and western New Hampshire.

Temperatures will bottom out in the 50s in all areas tonight.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
High pressure will build towards the East Coast on Tuesday
bringing dry conditions to the region. A west to northwest flow
will allow for mostly sunny conditions downwind of the mountains
due to downsloping. A few more clouds will linger in the
mountains during the day. Temperatures will climb through the
70s for afternoon high temperatures.

Mostly clear and cool conditions are expected Tuesday night.
There may be some late night clouds arriving over western New
Hampshire towards morning as the next front system approaches
from the west.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
With low pressure becoming vertically stacked between James Bay
and the UP of Michigan, the associated cold front will move
through the region Wednesday through Thursday. Out ahead, warm
and moist air will advect into the region. Highs Wed should
reach the mid to upper 70s, with southern locations bumping into
the 80s. Overall, guidance continues to agree on general onset
of precip late Wed afternoon, with rain and thunder continuing
overnight.

As previously alluded to, the speed of departure of the front
remains more uncertain. Showers will likely be continuing for
far eastern areas come Thursday afternoon. Additional forcing
may arrive along the coastal plain with the formation of low
pres amid the boundary into Thurs evening and overnight. This
would keep rain showers in the forecast for another night,
finally exiting Fri morning. This area of lift comes as a
strengthening upper jet entrance region begins moving north with
the longwave trough trending negative from a neutral tilt.
Current forecast aligns with the ECMWF and GEM showing this
feature; a right entrance region w/ divergence aloft conducive
to increased precip intensity and coverage. The quicker GFS
suppresses this idea as the region falls below the less
favorable sinking motion of the left entrance.

The trough moving off the coast into Friday will also be
responsible for guiding Larry in the open Atlantic. As dry
conditions work into the area for much of the weekend, long
period swell and increased wave heights will impact the coast
with possible erosion and threat of rip currents. Temperatures
will trend to around normal through the period with daytime
highs in the 70s and overnight lows in the 50s, with some 40s in
the higher terrain. Another upper low will progress south of
James Bay by early next week which could bring more showers to
the region.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Short Term...VFR conditions will prevail with clearing skies.
There may be some late night patchy fog in the northern valleys
as well as the Connecticut River valley. VFR conditions expected
Tuesday and Tuesday night.

Long Term...VFR conditions will prevail Wed afternoon, with
brief MVFR possible around showers/thunder in NH terminals.
Ceilings will lower to IFR overnight with continuing rain and
breezy southerly winds. West wind shift occurs Thurs afternoon
with IFR improving to MVFR Thursday evening. VFR Friday.

&&

.MARINE...
Short Term...Low pressure centered to the north crosses the
waters today, pushing a cold front with potentially gusty
showers or storms into this evening. Conditions are not
expected to reach SCA thresholds, however gusts to 25+ kts are
possible with showers/storms this evening. Winds turn westerly
behind the system tomorrow as high pressure crosses the East
Coast.

Long Term...An SCA will likely be needed beginning Wed afternoon
for increasing southerly winds as well as wave heights
overnight. Wave heights will continue to run about 5 to 6 ft
Thurs and Thurs night, increasing 5 to 9 ft Friday with
increasing long period swell from Larry. Waves and swell will
begin to decrease into the weekend.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.

&&

$$



Area Forecast Discussion...UPDATED

National Weather Service Chicago/Romeoville, IL

 912 PM CDT Mon Sep 6 2021

.UPDATE...
912 PM CDT

The forecast message for the rest of tonight and into a windy
Tuesday looks on track. Have added some more detail on the
specific timing for storms into the forecast for Tuesday, which
looks like a 1-2 hour duration in places that experience storms.
The best chances look to be along and southeast of a line from
O-Hare through Pontiac.

The old frontal boundary remains draped near the far southern CWA
edge this evening, with a few clouds lingering along it but all
showers having faded or pushed southeast. This front is starting
to creep northward in Iowa and should do the same overnight in our
area with no fanfare. The inversion that has set-up though will
be a factor in how quickly the wind gusts come up Tuesday. Looking
at forecast soundings from the RAP and HRRR and assuming high
clouds are not thick in the morning, it seems by 10-11 A.M. that
enough warming will have occurred that tapping into 35 mph gusts
is likely and by 12-1 P.M. some 40 mph gusts are probable. Highs
in the mid-upper 80s look good, supported by early September
climatology of 22-23C 925mb temperatures and 19C 850mb
temperatures.

Synoptic scale forcing and frontal timing in guidance solutions
remain in good agreement to support the cold front moving through
the CWA during the afternoon and clearing the southeast area
sometime during the early evening. For the Chicago area, the 2-5
p.m. window seems the most likely for developing storms. Coverage
should be higher on the front the further east along it due to
greater convergence, so that`s why the eastern CWA is most favored
with higher PoPs and the potential for gustier storms. As for the
outlook on some strong to possibly scattered severe storms along
the convective broken line, that continues to look supported by
incoming guidance trends, including lapse rates, wind fields, and
convection-allowing model output convective gusts (spotty 45+ mph
in the Lower Great Lakes region).

MTF

&&

.SHORT TERM...
220 PM CDT

Through Tuesday night...

The primary weather concern continues to focus on the threat of
severe thunderstorms Tuesday afternoon through very early evening
as a cold front shifts into northern IL. Gusty southwest winds of
35 to 40 mph are also expected Tuesday prior to the arrival of
the front during the afternoon.

Surface low pressure will develop and deepen into southwestern
parts of Ontario tonight in response to an amplifying mid-level
impulse and a ~115 kt upper jet streak over the Northern Plains
and Upper Midwest. This low is likely to deepen to around 995 mb
on Tuesday as it approaches the north central shores of Lake
Superior. Its associated cold front will then be driven southward
across northern IL and northwestern Indiana Tuesday afternoon
through early evening. Southwesterly winds will become gusty
up to 35 to 40 mph during the morning into the afternoon in
advance of this approaching cold front as the surface gradient
strengthens across the region.

Warmer temperatures into the middle to upper 80s will accompany
these gusty southwest winds Tuesday afternoon just ahead of the
approaching cold front. While a lingering surface ridge of high
pressure over the Gulf Coast will cut off better Gulf Moisture
from reaching the area, it does appear that a corridor of surface
dew points in the middle 60s over the Plains will advect
northeastward ahead of the front. This should be sufficient to
result in MLCAPE values up around 1500 J/KG during peak heating in
the afternoon. Initially, warmer temperatures aloft should act as
a cap to surface based convective development, especially early
in the afternoon. However, capping should weaken and likely will
erode with time during the mid to late afternoon hours as falling
heights and cooling temperatures aloft overspread the area in
association with the digging upper trough over the western Great
Lakes. This will thus support thunderstorm development over at
least parts of northern IL and northwestern IN after 3 pm Tuesday.

The storms may develop right overhead across northeastern IL
Tuesday afternoon as the cap erodes. Storm coverage may initially
be more widely scattered, and for this reason, parts of far
northern IL in and around the Rockford area may see rather sparse
coverage, with more storm development likely to their southeast.
Storm coverage does then look to ramp up some later in the
afternoon as the cold front shifts towards the I-55 corridor and
the exit region of the aforementioned 115 kt upper jet begins to
nose into the area. Given the favorable kinematics, organized
linear storm clusters and supercells will be favored. Strong
damaging winds look to be the primary severe threat, though some
severe hail threat and even a brief tornado threat will exist with
any super cell storm structures. The highest threat for scattered
severe thunderstorm coverage is generally along and east of the
interstate 55 corridor from around 3 pm through 8 pm. This
includes much of the Chicago metro area.

The threat of storms will come to a quick end from northwest to
southeast early in the evening as the cold frontal passage occurs.

KJB

&&

.LONG TERM...

Wednesday through Monday...

209 PM...No significant forecast concerns currently, though and
active pattern is possible this weekend into early next week.

Northwest winds will likely remain gusty on Wednesday, possibly
into the 25-30 mph range. These strong winds and northwest
directions will lead to higher waves along the northwest IN Lake
Michigan shore though confidence is only medium for a high swim
risk. Still a few days away to monitor trends, but a high swim
risk is possible, mainly for Porter County.

As cooler air spreads across the Great Lakes region Wednesday
night into Thursday, there will be a chance for lake effect rain
showers. Wind directions appear to stay northwest enough that only
northeast Porter County would be effected by any possible showers
but did include slight chance pops for this potential.

High pressure will move across the area Thursday into Thursday
night with a lake breeze expected Thursday afternoon. Southerly
flow returns Friday with temperatures warming into the lower 80s.
All of the models show a cold front moving across the area
Saturday afternoon or into Saturday night but not much in the way
of precipitation with the best forcing well north and northeast of
the area. Blended pops are dry for this time period and maintained
a dry forecast. However, ahead of this front there may be an axis
of very warm air with highs in the mid to possibly upper 80s.
Beyond this time period, models diverge with the GFS much cooler
behind the front while the ECMWF slows, stalls, then lifts the
front back north leaving Sunday/Monday generally in the 80s,
except for any possible lake cooling. Confidence too low to
differ from the blended guidance which maintains highs in the 80s
for this time period along with no precipitation. cms

&&

.AVIATION...
For the 00Z TAFs...

Concerns:
-Gusty SW winds Tuesday morning through mid afternoon
-Scattered to broken line of thunderstorms mid to late afternoon

The lake breeze is still on the move this evening given the
overall light wind profile in place under a ridge of high
pressure. This should wash out fairly soon and then expect winds
to shift to a SE direction this evening before increasing out of
the SSW overnight.

A fairly strong low pressure system will pass over
northern/central Lake Michigan on Tuesday. SW winds will increase
in advance of an associated cold front. Winds will veer to more of
230-250 direction by midday to hopefully alleviate cross runway
concerns at ORD. Gusts into the mid to upper 20 kt range in the
morning are likely, and the lower 30 kt range seem a fairly
decent bet mid to late morning into the early afternoon, locally
slightly higher.

A scattered to broken line of thunderstorms should develop on
Tuesday afternoon. These may develop right over the Chicago
terminals. There is still some uncertainty as to the coverage,
with the highest confidence from Chicago eastward over Lake
Michigan, but confidence has increased enough to include 2 hr
TEMPO windows for TS in the Chicago metro. Thunderstorms should
not be too long lasting, but expect gusty NW winds in these also.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...LMZ743-LMZ744-LMZ745...9 AM Tuesday to 10
     PM Tuesday.

     Small Craft Advisory...LMZ740-LMZ741-LMZ742...9 AM Tuesday to 7
     PM Tuesday.

&&

$$

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



...Updated Aviation Forecast Discussion...



 .DISCUSSION...
Issued at 303 PM CDT Mon Sep 6 2021

.Tonight and Tuesday:

A vigorous short-wave trough over south-central Canada is
forecast to undergo considerable amplification while moving into
the Great Lakes on Tuesday. In the low levels, an associated cold
front will advance through the northern Plains tonight and through
the mid MO Valley on Tuesday.

Current visible satellite imagery reveals a considerable amount of
smoke over the northern High Plains, which will be advected into
the area tonight into Tuesday as mid-level winds strengthen from
the northwest. HRRR forecasts suggest that the majority of the
smoke will remain aloft, resulting in mainly a hazy appearance to
the sky. Smoke concentrations should begin to diminish by Tuesday
night.

In regard to the cold front, latest RAP/HRRR forecasts suggest
that the boundary will move into our northwest counties by 10z (5
AM Tuesday) before reaching the Omaha and Lincoln areas by 13z (8
AM). Winds will switch to north-northwest behind the front with
sustained speeds of 15-20 mph and gusts of 30-35 mph. Winds should
gradually diminish during the afternoon hours. Highs on Tuesday
will range from the upper 70s north to mid 80s south. No
precipitation is expected with the frontal passage.

.Wednesday through the weekend:

A prominent mid-level ridge over the interior west is forecast to
expand east into the Great Plains through the remainder of the
work week. In response, high temperatures in the upper 70s to
lower 80s on Wednesday will warm into the mid 80s to around 90 by
Friday.

By this weekend, a short-wave trough is forecast to move through
the northern Plains with an associated surface cold front
advancing through the mid MO Valley. That scenario would support
slightly cooler temperatures. Measurable precipitation chances
currently appear low.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 615 PM CDT Mon Sep 6 2021

Southerly winds will diminish shortly after 00Z this evening and
veer to the west, and eventually northwest by early Tuesday
morning as a cold front moves into the region. Northwest winds
will be gusty from around 13-15Z through Tuesday afternoon. LLWS
will be possible primarily at KLNK and KOMA between 07-14Z
tonight. LLWS could also creep into KOFK briefly from 11-13Z as
well. Otherwise, expect VFR conditions through the period.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

$$

DISCUSSION...Mead
AVIATION...KG



Area Forecast Discussion

National Weather Service Phoenix AZ

 512 PM MST Mon Sep 6 2021

.UPDATE...Updated 00Z Aviation Discussion.


&&

.SYNOPSIS...
Strong high pressure aloft will be the predominant weather feature
across the Southwestern U.S. this week providing above normal
temperatures for much of the region. Generally dry conditions
will also prevail despite somewhat higher humidity levels, though
slight chances for storms may become possible later this week
across southeast California and the Arizona higher terrain. Daily
high temperatures will mostly range from 105 to 108 degrees across
the Arizona lower deserts to a couple of degrees warmer across
southeast California and southwest Arizona.

&&

.DISCUSSION...
RAP streamlines depict a large anticyclone centered
across the Great Basin. Abundant dry air aloft is also evident on
water vapor imagery, though conditions remain somewhat moist at
the surface, particularly across portions of southeastern
California. In the Imperial Valley, dewpoints in the mid 70s are
resulting in heat indices as high as 115 deg. Meanwhile, afternoon
ACARS soundings out of KPHX reveal a warm and dry layer around
700 mb, which is yielding a considerable amount of convective
inhibition. HREF confirms conditions will remain quite unfavorable
for Monsoon thunderstorm activity for the remainder of today.

The aforementioned anticyclone will remain the predominant
weather feature through the week. GEFS/ECWMF/CMC ensemble suites
remain in good agreement the high will shift eastward and then
southward through the week. The models also indicate the strongest
height anomalies will remain to our north and east. Main impact
across the Desert Southwest will be a warming trend with
temperatures likely peaking mid-late week.

Latest NBM guidance puts the Phoenix Metro area a bit below
criteria for an Excessive Heat Watch Wednesday/Thursday, though if
trends continue, a Watch or Warning may ultimately be needed. For
Wednesday and Thursday, there is currently a 25-35 percent chance
the high temperature will reach or exceed 108-109 deg in Phoenix,
which roughly corresponds to a high heat risk this time of year.
Latest GEFS/ECMWF ensemble temperature distributions depict a
reasonable amount of uncertainty, and it is still conceivable the
record high temperature of 110 deg (both days) could even be
reached. Uncertainty increases more Friday through Monday, though
temperatures will likely remain above average.

With relatively dry and warm air circulating around the ridge,
conditions will remain unfavorable for Monsoon storms at least
into the weekend. The only exceptions will be across the higher
terrain of Gila County and extreme southern Maricopa County. Only
a handful of GEFS/ECMWF ensemble members suggest precipitation
will reach the lower deserts of south-central Arizona. Latest
ECMWF ensembles suggest the best chance of precipitation may
actually be along the Colorado River Valley Thursday-Saturday as
GOC moisture is pulled northward.

&&

.AVIATION...Updated at 0010Z

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

Diurnal wind tendencies are favored through the TAF period at
most terminals with speeds mainly 8 kts or less. At KPHX, winds
are expected to remain westerly or southwesterly through the next
24 hours with a slight uptick in speed up to 12 kts tonight
following a gulf surge. There are indications winds may still try
to shift east, or become variable, around 11-12Z, but the
probability is currently too low to include in the TAF. Skies will
remain clear outside distant afternoon cumulus.

Southeast California/Southwest Arizona including KIPL and KBLH:

Winds will favor the south at KBLH and east to south at KIPL
through the TAF period, with periods of variability in the
morning. Speeds will mostly be 8 kts or less, besides typical
afternoon gusts and a brief uptick to 10-15 kts tonight following
a southerly gulf surge. Skies will remain mostly clear.

&&

.FIRE WEATHER...
Wednesday through Sunday:
Strong high pressure will dominate over the Great Basin into the
Desert Southwest late this week into the weekend providing
generally dry conditions and above normal temperatures. Chances
for showers and thunderstorms will be very limited through the
period, especially over the Arizona lower deserts where chances
will be less than 5%. High temperatures are likely to run a few
degrees above normal throughout the period with some lower desert
areas potentially seeing a return of 110 degree readings. Min RH
levels will mostly range from 15-25% through the forecast period,
while max RHs generally range from 40-60% (locally higher). Apart
from thunderstorms, strong wind events are not anticipated.

&&

.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Excessive Heat Warning from 10 AM Tuesday to 8 PM PDT Wednesday
     for CAZ561-570.

&&

$$

DISCUSSION...Hirsch
AVIATION...Benedict
FIRE WEATHER...Kuhlman