Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/17/22

Area Forecast Discussion...UPDATED

National Weather Service Albuquerque NM

 856 PM MDT Mon May 16 2022

.UPDATE...
Convection has mostly moved east into TX this past hour, and the
severe threat has ended. Therefore the Severe Thunderstorm Watch
across eastern NM will be cancelled.

&&

.PREV DISCUSSION...517 PM MDT Mon May 16 2022...
.AVIATION...
00Z TAF CYCLE
VFR conditions prevail and are forecast to persist, except for
potential MVFR vsbys in blowing dust from convective outflow at KTCC
and KLVS later this afternoon. A round of iso/sct convection will
continue through this evening across eastern NM, with the potential
for strong outflow gusts to 50-60kts through 04Z. Low level flow
will pick up out of the W-SW Tuesday.

&&

.PREV DISCUSSION...317 PM MDT Mon May 16 2022...
.SYNOPSIS...
Scattered showers and thunderstorms in eastern New Mexico will shift
eastward into Texas an hour or two after sunset. Elsewhere, westerly
breezes will bring dry air back into western and central New Mexico
tonight. Dry and breezy weather is forecast for all areas Tuesday. By
Wednesday, another weak front will bring chances for showers and
thunderstorms to northeast New Mexico. Breezy and dry and very warm
to hot weather returns to all areas Thursday with strong winds
possible Friday and Saturday.

&&

.DISCUSSION...
.SHORT TERM (TONIGHT THROUGH TUESDAY NIGHT)...
A round of daytime heating triggered convection is underway along a
slowly sharpening dryline as a Pacific trough approaches from over
western AZ. Showers and storms will favor areas along/east of the
central mountain chain late this afternoon and early evening before
moving off into the TX/OK Panhandles per the latest HREF, HRRR
and NAM solutions. We`re still anticipating a mix of wet/dry storms
that will lean more on the dry side along the central mountain chain
and adjacent eastern highlands. Will likely see a mixed storm mode
scenario, with potential for supercell thunderstorms although 0-6km
bulk shear is lacking a bit at 30-35kts. The main threat with
this convection will be strong/damaging wind gusts given dCAPE
values ranging between 1500-2000 J/kg. The weak Pacific trough will
move over early Tuesday, bringing breezy to locally windy westerlies
that will scour out any remaining moisture across the east central
and northeast plains. Tuesday will feature breezy to locally windy
westerlies with well above normal temperatures that will approach
daily record high across much of the area. Another, weaker, backdoor
cold front will slide down the eastern highlands/plains Tuesday
night, resulting in a northerly wind shift.

LONG TERM...(WEDNESDAY THROUGH SUNDAY)...
Transitory ridge axis moves over NM Wednesday morning, followed by a
diffluent flow aloft ahead of a weak upper-level trough over AZ
during the afternoon. High based cumulus development is likely over
most mountain ranges with virga shafts and sprinkles and a dry storm
or two possible central and west with wetter showers and storms from
the Sangre de Cristo mountain crest eastward. The wetter showers and
storm chances are the result of another backdoor front/boundary with
Gulf moisture that moves into the northeast NM Wednesday morning.
Models are trending less windy for Thursday, digging the above
mentioned trough farther southeast into southeast AZ and slowing its
eastward progress. While winds will likely increase somewhat Thursday,
latest model forecast suggesting it could be late-day Thursday
before winds start to pick up. Another upper-level short-wave trough
within the long wave trough over Canada and northern tier states is
forecast to slide southeast through the Great Basin Thursday night.
Winds aloft ramp up significantly Thursday night with widespread
40-55kt speeds at 700mb. Friday continues to look windy to very
windy with models now developing a surface low over near Clines
Corners with the associated surface cold fronts (Pacific and
backdoor) moving through Friday evening. GFS sends a strong backdoor
surge southward through eastern NM Friday night. At this point
showers and thunderstorms will favor far north-central NM Friday
night into Saturday where the two surface front converge. Breezy to
windy condtions result for central and eastern NM Sunday, thanks to a
strong return flow set up.

11/33

&&

.FIRE WEATHER...
...FIRE WEATHER WATCH TUESDAY AFTERNOON AND EVENING FOR THE EASTERN
PLAINS DUE TO LOW HUMIDITY, GUSTY WINDS AND AN UNSTABLE ATMOSPHERE...

A mixed wet/dry round of showers and storms will impact areas from
the central mountain chain east to the TX/OK borders this afternoon
and evening, with some dry lightning and strong/erratic wind gusts.
Spotty critical fire weather conditions will prevail late this
afternoon and early this evening west of the central mountain chain.
Hot, dry and unstable conditions will continue Tuesday, with
moderate westerlies leading to a few hours of critical fire weather
condtions across the eastern plains, where a Fire Weather Watch is
in effect. Hot, dry and unstable conditions will persist Wednesday,
although with wind below critical threshold. A backdoor front will
bring a wind shift to eastern NM Tuesday night into early Wednesday,
with sufficient moisture behind it for a late day round of
convection across northeast NM. The westerlies will trend up
Thursday and couple with a deepening lee side trough to bring a
round of critical fire weather conditions. However, winds are back
on the downtrend for Thursday and may be a limiter in terms of how
much of the area will be impacted by critical fire weather
conditions. Stronger winds will impact the area Friday as a trough
moves east toward the southern Rockies and northern NM, with several
hours of critical fire weather conditions likely. A cold front will
race south across the area Friday night and bring a break from
critical conditions for Saturday. The forecast becomes more
uncertain beyond Saturday, with the potential for more critical fire
weather conditions going into early next week.

11

&&

.ABQ WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Tuesday afternoon through Tuesday evening
for the following zones... NMZ104-108.

&&

$$



Area Forecast Discussion...UPDATED

National Weather Service Aberdeen SD

 854 PM CDT Mon May 16 2022

.UPDATE...
Issued at 850 PM CDT Mon May 16 2022

Overall the forecast looks on track. The latest HRRR continues to
show late night convection forming on the nose of an eastward
migrating moderate LLJ. That activity will likely persist in the
east through part of Tuesday. Temperatures look fine for now.

&&

.SHORT TERM...(This Evening through Tuesday Night)
Issued at 343 PM CDT Mon May 16 2022

The forecast challenge is timing, coverage and strength of overnight
convection.

At 2 PM CDT, abundant sunshine is noted over the entire CWA while
surface high pressure hangs on across the eastern Dakotas.
Southeasterly return flow winds have begun to develop west of the
James River valley this afternoon, while light and variable or light
northerly surface winds persist across far northeast South Dakota
and west central Minnesota. Temperatures have warmed into the 60s
and 70s.

The stage will be set for some elevated showers and thunderstorms
later tonight and continuing into the day on Tuesday. There is a
shortwave noted moving out of Idaho and timing it out, it should be
working through the CWA later tonight. There is a low level jet to
help focus convection, as well as some fine low to mid-level WAA and
adequate mid-level moisture advection happening tonight/Tuesday. Mid-
level lapse rates are forecast to steepen to 8+C/km across the
southern half of the forecast area. Elevated/cloud-bearing shear
environment appears to be supportive of rotating updrafts, and
MUCAPE tonight at KPIR is progged to increase from ~50J/kg to over
1000J/kg. Probably will just see some generic thunderstorms
overnight. But, given this set-up, would not be surprised if a few
storms end up producing some hail tonight.

Convection should weaken/wane by early Tuesday afternoon, leaving
the rest of the short term dry. Temperatures on Tuesday could be a
little cooler than the past couple of days, if it stays cloudy/rainy
for most of the day across the eastern half of forecast zones.

.LONG TERM...(Wednesday through Monday)
Issued at 343 PM CDT Mon May 16 2022

The main forecast challenge will be thunderstorm and severe
potential Wednesday night into Thursday. A shortwave trough will be
moving through ND and MN Wednesday morning and afternoon, and a dry
cold front will shift winds to the northwest through this time.
Breezy conditions are anticipated across the northern CWA, with high
temperatures in the 70s under partly cloudy skies. Meanwhile, models
are all in agreement about bringing in a larger, positively tilted
and deep upper-level trough from the northwestern US. By Wednesday
evening, sfc low pressure develops on the lee of the Rockies near
the SD/NE/WY borders. If a sufficiently strong LLJ can develop
overnight, thunderstorms may develop in a good shear environment.

A strong sfc low pressure system (990s mb) will then move across
South Dakota on Thursday. Out ahead of the low and in the warm
sector, environmental parameters do favor severe weather potential
by the afternoon/evening hours: low-level moisture with dewpoints of
60+F, steep lapse rates, sufficient instability and deep layer
shear, etc. The speed/timing of this system will be an important
factor for how much of the CWA has a chance for strong to severe
storms. A majority of the GEFS ensemble members are clustered into a
slower solution, which may place the low and cold front closer to
the James Valley by 00z (increasing the coverage of potential storms
in the forecast area), whereas the majority of the Canadian and
ECMWF members depict a faster solution, which would place the system
further east by that time (decreasing coverage of potential storms
in the forecast area). Future model runs will paint a clearer
picture on timing, and the overall threat potential.

A strong cold front passes Thursday evening/night, leading to gusty
northwest winds on Friday and much cooler air, with highs in the low
to mid 50s. Low temperatures may even approach or reach 32 F Friday
night and Saturday night across the area, especially if skies can
clear and winds can become light as large sfc high pressure builds
in. Something else to keep an eye out for is potential instability
showers and storms due to steep lapse rates from cold air aloft and
warmer air near the sfc Friday through Sunday, leading perhaps to
some graupel.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 606 PM CDT Mon May 16 2022

Terminals KABR,KATY,KPIR,KMBG

VFR skies/vsbys are expected through tonight. Scattered late night
showers and thunderstorms are also expected just about anywhere
over the region.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

UPDATE...TDK
SHORT TERM...Dorn
LONG TERM...Lueck
AVIATION...TDK



Area Forecast Discussion

National Weather Service Bismarck ND

 908 PM CDT Mon May 16 2022

.UPDATE...
Issued at 852 PM CDT Mon May 16 2022

Light radar returns continue crossing over portions of the
forecast area, mainly in central ND. Still not expecting much more
than sprinkles at this point in time for now. However, ceilings
are starting to lower a bit and dewpoints depressions have come
down significantly. Most CAMs suggest better shower activity won`t
begin to occur until later tonight. However, the RAP suggests
scattered showers in central North Dakota around this time.
Depending on how things evolve over the next hour or so, may add
scattered showers through the remainder of the evening into early
tonight.

UPDATE Issued at 638 PM CDT Mon May 16 2022

Light radar returns continue from northern Stutsman through
eastern Mountrail counties and north. However, very dry air
persists with dewpoint depressions generally 20 degrees or more,
and ceilings of 10 kft or more. Therefore, most returns are virga
with a few sprinkles reaching the ground. In addition, with
transient clouds over most of the forecast area, increased sky
cover over areas that were limited in coverage.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 250 PM CDT Mon May 16 2022

Chances for rain and high temperatures in the 60s and 70s
highlight the short term.

Currently a band of light rain stretching from Glasgow to
Bismarck is moving east through the area. This band is associated
with a very small short wave trough embedded in the general ridge
aloft. Most of this rain is not reaching the ground based on low
reflectivity and surface observations. The only location that has
reported rain is Williams County. This rain band should continue
to work eastward through the rest of the afternoon, slowly
weakening as the shortwave moves east. Mid to upper level clouds
cover most of the western half of the state currently, and should
continue through most of the night and into Tuesday.

Tuesday morning a little disturbance in the flow from the Northern
Rockies moves through North Dakota bringing widespread chances of
rain for the area. A clipper also works south from Canada at this
time bringing another slight chance of rain to our far northeast
Tuesday night. Clouds will decrease from west to east as that
disturbance moves out.

Temperatures through this period will still be mild, thanks to the
ridging aloft. The lows tonight will be in the upper 40s, with a
few locations only getting down to the lower 50s. Highs Tuesday
range from the lower 60s in The James River Valley, to the mid 70s
in the west.

.LONG TERM...(Wednesday through Monday) Issued at 250 PM CDT Mon
May 16 2022

More chances of rain and some cooler temperatures are the main
highlights for the long term.

Wednesday morning the aforementioned clipper moves off to the
east, as a shortwave ridge starts to builds in from the west.
High temperatures will be similar to Tuesday, ranging from the
lower 60s in the north to the lower 70s in the south. Thursday
morning another Alberta clipper develops and starts to push the
ridge off to the east. The ridge axis moves to our east as
southwest flow starts to take over early in the morning.
Widespread rain is likely with this clipper, along with cooler
temperatures and breezy conditions. Highs will struggle to reach
the the 60s, with most locations staying in the 50s. This chance
of rain looks to continue through Friday, where we will see our
coldest temperatures of the week. Highs look to only reach into
the upper 40s, with maybe a few cities touching the 50s. A
positive tilted trough develops with this clipper. The chance for
rain will then end when this trough axis moves east of our area.
On the Cluster analysis, a great amount of uncertainty remains
with the timing of this trough. This signal has remained
consistent over past few days.

The chance to see a few snowflakes is also possible in the west
with this system. Models have temperatures at 850mb below
freezing Friday through Saturday. With snow mixing with rain and
surface temperatures well above freezing, no snow will accumulate
of course. Saturday evening another shortwave embedded in the
back side of the trough could move through, giving us another
slight chance of rain.

Sunday looks to be dry, with temperatures warming back
into the 60s through Monday. Another Alberta clipper could move
through Monday, bringing another chance of rain to the area.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 638 PM CDT Mon May 16 2022

For the most part, VFR ceilings and visibilities are expected
through the TAF period, although KBIS may drop to MVFR ceilings
late Tuesday morning and into the afternoon. In addition,
scattered showers, perhaps with a few rumbles of thunder, across
the area could result in brief reductions in ceilings and
visibilities for every TAF site. The exception is KXWA which
looks likely to remain west of any rain showers.


&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...Telken
SHORT TERM...Smith
LONG TERM...Smith
AVIATION...Telken



Area Forecast Discussion

National Weather Service Des Moines IA

 640 PM CDT Mon May 16 2022

...Updated for the 00z Aviation Discussion...

.SHORT TERM.../Tonight through Tuesday/
Issued at 303 PM CDT Mon May 16 2022

Key Messages:

-Thunderstorms return early Tuesday morning with severe chances
 later on in the evening.
-another round of strong to severe thunderstorms possible late
 Thursday into Thursday night.
-Much cooler this weekend.

Discussion:

An area of surface high pressure will continue to preserve fair
weather into this evening over much of Iowa. A deep mixed layer
allowed for wind gusts over 20 mph to mix down. Higher gusts over
35 mph persisted over northeast Iowa where a tighter pressure
gradient existed. Winds will begin to slow down near sunset.

A surface low pressure system will intensify over the central
Plains overnight and gradually make its way towards the Midwest.
Showers and some rumbles of thunder are possible in the morning
in the north due to the LLJ and boundary interaction. Instability
will develop especially in southern Iowa during the day, setting
up for the main convective event in the evening. The severe
threat will be highest in southwest portions of the state before
sunset. SBCAPE and shear are marginal and support hail and
damaging winds primarily. The LLJ will return after dark and
support elevated storms overnight in south-central Iowa. PWATS
remain near 1.5 inches in this area, signaling a chance for high
rainfall totals, especially if storms have an east-west
orientation as some CAMs suggest. Highest rainfall totals are
expected across southern Iowa into Missouri.

&&

.LONG TERM.../Tuesday night through Monday/
Issued at 303 PM CDT Mon May 16 2022

Tuesday Night into Wednesday...Forecast Confidence: Medium to
High

Modest forcing from upper shortwave combined with the
reintensifying low level jet will keep scattered to numerous
showers and thunderstorms ongoing into Tuesday night, especially
along and north of the sfc warm front. As the night wears on,
midlevel lapse rates become increasingly moist adiabatic. While
there is a resevoir of MUCAPE > 1000 J/g and modest effective
shear, feel the threat will quickly evolve from strong storms to
locally heavy rainfall. As noted, higher freezing levels, PWATs
around 1.5 in, and skinnier CAPE profiles could lead to pockets of
heavy rainfall. The greatest threat for heavier rain appears to
be across southern Iowa or northern Missouri but will be dependent
upon the location of the low level frontal zone. The 12Z HREF
local probability matched mean /LPMM/ and recent runs of the HRRR
are also showing areas with greater than 2", which agree well with
the Marginal Risk of excessive rain from WPC.

Frontal zone should push east of the area on Wednesday with weak
high pressure moving into the region. After a few lingering
showers on Wednesday morning, expect partial clearing by
afternoon. Highs on Wednesday should be close to seasonal averages
in the 70s.


Thursday thru Monday...Forecast Confidence: Medium

A much stronger upper trough will develop over the northern
Rockies on Thursday and then slide eastward and deepen over the
central CONUS by late week and into the weekend.

Expect a breezy and warmer day on Thursday as southerly flow
develops head of a strong sfc low over the High Plains. Expect
temperatures to rise into the low to mid 80s with dewpoints
creeping back into the 60s. There is better model agreement on the
cold front front sweeping southeastward across the state on
Thursday evening through Thursday night. Ahead of the front, the
deterministic models and ensembles are indicating about 1500-2500
J/kg of MLCAPE and moderate deep layer shear of 30-40kts. Plenty
of details yet to be ironed out but will need to watch this period
closely. The SPC Day 4 Slight Risk appears on track attm.

Windy and much cooler air is expected behind the cold front on
Friday, with the deep upper trough lingering over the upper
Midwest into the upcoming weekend. Expect much cooler than normal
average temperatures to return with highs on Saturday and Sunday
only reaching 50s and 60s, along with a few chances for showers.
If we clear out on Saturday night, we could even be talking about
areas of frost, with low temps forecast in the mid to upper 30s in
the north...brrr.

&&

.AVIATION.../For the 00Z TAFS through 00Z Tuesday evening/
Issued at 640 PM CDT Mon May 16 2022

VFR conditions will prevail through the TAF period, however,
SHRA/TSRA chances will return with a concurrent potential for
periods of MVFR or lower conditions. The first such chance will
come early Tuesday morning at the northern terminals, then a
second, more widespread round of TSRA may occur between Tuesday
afternoon and Tuesday night. With low confidence in precise
timing/location at this range, have covered with VC groups at all
terminals.

&&

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

&&

$$

SHORT TERM...Jimenez/Fowle
LONG TERM...Fowle
AVIATION...Lee



AREA FORECAST DISCUSSION

National Weather Service Sioux Falls SD

 1047 PM CDT Mon May 16 2022

.SHORT TERM...(This Evening through Tuesday)
Issued at 316 PM CDT Mon May 16 2022

Weak surface ridging centered over eastern KS and western MO this
afternoon will shift off to the southeast this evening, while a
surface high over southern Canada pushes into the Northern Plains.
This will drive a back door cold front through our area during the
evening, which will become stationary along the southern edges of
our CWA overnight. CAMs continue to indicate shower and isolated
thunderstorm development toward 06Z tonight, focused north of
Interstate 90 with increasing mid level theta e advection as a low
level jet strengthens overnight and a weak midlevel shortwave tracks
through the region. Not expecting any strong storms overnight -
with any significant instability well to our south - but with a
few hundredths J/KG of elevated CAPE in place, cannot rule out
some isolated thunder. It will be a milder night with lows in the
50s.

For Tuesday, CAMS indicate that a few showers and thunderstorms will
remain possible through the day, though stronger instability remains
south of our area for the first half of the day. By afternoon,
stronger instability begins to nudge northward into the the MO River
corridor in the vicinity of a warm front lying across the region as
a surface low rides through Nebraska during the afternoon and
evening. Because of that, there is a risk of strong to severe storms
over this area during the evening if convection can develop, though
RAP analysis suggests that the better 0-6 km bulk shear will be
displaced from the better instability, so a marginal convective risk
as issued by SPC still seems appropriate. With the front sitting
along our southern border, there will be a wide range of
temperatures for Tuesday with highs in the lower to mid 60s over
southwestern MN to mid and upper 70s south of Interstate 90.

.LONG TERM...(Tuesday Night through Monday)
Issued at 316 PM CDT Mon May 16 2022

Any showers and thunderstorms move off to the east by Wednesday,
leading to a dry and slightly warmer day with highs in the mid 70s
to near 80. A cold front slides through the area by afternoon, and
the GFS continues to produce thunderstorms over south central SD
during the evening, though it is the only model that does so, thus
the forecast remains dry.

By Thursday a warm front lifts northward across the area as low
pressure deepens over central SD, then pushes a cold front through
the area on Thursday night as the low moves to the east. With
increasing instability in the warm sector and strong bulk shear, this
will be our next chance of strong to severe storms as outlined in
the SPC day 4 convective outlook.

Big changes are in store for the end of the week as an upper level
trough settles into the region on Friday and Saturday. This will
bring much cooler temperatures as highs fall back into the 50s to
lower 60s with lows in the 30s to lower 40s. Although there could be
a couple shots of precipitation during that time frame, model
differences yield a dry forecast for the end of the week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1047 PM CDT Mon May 16 2022

Light scattered showers and isolated thunderstorms remain possible
after midnight throughout the overnight period, with majority of the
activity expected to be north of I-90. Another round of showers are
likely by the late morning hours into the afternoon, with MVFR cigs
likely developing for areas north of I-90 and moving southwards into
the evening. Stronger thunderstorms are possible during the late
afternoon into the evening hours, primarily for areas south of the I-
90 corridor.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...JM
LONG TERM...JM
AVIATION...APT



AREA FORECAST DISCUSSION

National Weather Service Hastings NE

 700 PM CDT Mon May 16 2022

.DISCUSSION...(This evening through Monday)
Issued at 405 PM CDT Mon May 16 2022

Main forecast concerns are strong to severe thunderstorm chances
with a pair of fronts Tuesday and Thursday, then cool down for
late week.

Summary:
Mild, dry and pleasant conditions will continue through
this evening. A low level jet will bring gradually increasing
moisture over the next 24 hrs, which may help to sustain
convection as it rolls off the high plains late tonight and into
Tuesday morning. Exactly how this pans out will play a role in
the afternoon/evening convective potential, and there remains
considerable amount of uncertainty. Wednesday appears dry before
another, but stronger, cold front arrives at some point Thursday
into Thursday evening. Storms may develop along this front as
well, but moisture quality may be lacking which could limit
coverage and severity. Much colder temperatures and chilly NW wind
will settle in for Fri into Sat, and there`s a non-zero chc that
at least portions of the forecast area may have to deal with
patchy frost early Saturday morning.

Forecast Details:
It`s been a quiet, mild, and breezy day thus far, and don`t see
any reason this conditions won`t continue through the evening hrs.
Convection can be seen developing over the higher terrain of
WY/CO, as a weak upper disturbance rounds the top of shortwave
ridging. Some of this activity will try to organize as moves off
the higher terrain to the E...but quality moisture is severely
lacking with sfc Tds only in the mid 40s to low 50s. So have my
doubts at how successful this activity will be at sustaining
itself after sunset further E. There will be an incr low level
jet, but the best convergence on the nose of the speed max looks
to be further N, closer to I-90...so perhaps convection sustains
and/or develops more efficiently in that area. Nonetheless,
various short-term and convective allowing models have non-zero
chcs for QPF after midnight and into Tue AM, so have maintained
some slgt chc PoPs. Am not expecting anything real widespread or
organized, and I think the lacking moisture and elevated nature of
convection would keep things below severe levels.

Assuming remnant cld cover isn`t overly thick/widespread, should
see another mild day on Tue with highs in the low 80s to near 90F.
Will state up front that details surrounding convection potential
Tue aftn/eve remain highly uncertain, including timing, placement,
coverage, and severity. In a general sense, looks like moisture
quality will improve, with time, which should combine with steep
mid level lapse rates and at least pockets of stronger insolation
to produce moderate instability ahead of a S/SE moving cold front.
Models are in good agreement that will be in zonal or slight NW
flow by peak heating, with several weak upper waves and neutral
or slight height falls towards eve. One potential source of
uncertainty will be any lingering vort maxima from Mon eve/night
convection. Some models have hinted at shortwave subsidence behind
one of these waves for our area, effectively limiting new dev for
peak heating. However, if convection remains weak, this may be
overdone. In terms of shear, deep layer flow remains weak by May
standards. Several forecast soundings indicate speeds less than
40kt thru the column, but do indicate strong directional shear
with low level SSE flow veering to WNW or even NW in the mid/upper
levels...resulting in 30-40kt of eff shear. So if convection can
dev, it falls within the CAPE/shear parameter space favorable for
at least iso strong to svr. As for coverage, timing, and
placement...hi-res models are all over the map...with some dev a
sold line, but mainly S of the KS/NE border...whereas others like
18Z HRRR and 12Z ARW and further N into central/sc Neb. May just
have to be one of those days where we don`t know a whole lot until
the details of tonight/tmrw AM shake out. Gut feeling is that 5pm
to midnight would be most likely time for strong/svr storms...and
that large hail and locally dmg winds would be main threats.

Nrly flow should clear us out for Wed, as well as bring us
slightly cooler temps in the upper 70s to low 80s and drier air.
Nothing to complain about for this time of year, for sure.

A stronger cold front is set to move through the region at some
point Thu into Thu night, but there`s still some spread on the
exact timing. It should be late enough that we see warm/hot
temps in the upper 80s to mid 90s ahead of the front. There is a
non-zero chc for storms to develop along the front by late aftn or
eve, but not sold that it will be widespread for our area owing to
lacking moisture. Decent SWrly low level flow will probably mix
out a lot of our BL moisture and shunt the greatest plume of
moisture off to our E. This could make it difficult to overcome
CIN until perhaps late in the day when mid-level height falls move
in. Mid to upper level flow is stronger, so if we can develop
better moisture/instability, there would likely be strong shear to
work with for large hail considering Srly sfc flow veering and
incr to 40-50kt NWrly flow at H5. Dmg wind would also be a concern
given LCLs near 3km and steep lapse rates/inverted V profiles.

Much cooler air is likely for late in the week and into the
weekend, with stiff/chilly NW wind likely on Fri. Pretty good chc
highs will remain in the 60s for one or both days near and N of
I-80, with perhaps southern areas making a run towards the low
70s. The good news is that it won`t feel at all humid,...the bad
news is that the cool/dry air will be at least a non-zero chc for
at least patchy frost Sat AM to our N/NW zones with lows in the
mid to upper 30s. Stay tuned if you have sensitive vegetation.



&&

.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 653 PM CDT Mon May 16 2022

Low-level wind shear (LLWS) will be the biggest concern heading
into the overnight. Strong and consistent signals make this high
confidence, with KEAR getting a slightly earlier start as the
low-level jet axis approaches there first, coming out of the south
southwest. Thunderstorms will also be of some concern, with some
potentially containing some gusty winds, but chances are not high
enough to mention more than VCTS for the overnight into early
Tuesday morning.

&&

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

$$

DISCUSSION...Thies
AVIATION...Heinlein



Area Forecast Discussion

National Weather Service Goodland KS

 900 PM MDT Mon May 16 2022

.SHORT TERM...(This evening through Tuesday Night)
Issued at 230 PM MDT Mon May 16 2022

As of 3 pm CDT...2 pm MDT...skies were partly cloud across most of
the region as high clouds move in from the west. Temperatures have
warmed well into the 80s for most locations. Winds varied from south
at 10 to 15 mph with gusts of 25 mph east of Highway 83 to sustained
20 to 30 mph and gusting up to 45 mph along the Colorado border. At
the surface, a lee trough has developed along the Colorado Front
Range. Aloft, a shortwave trough was moving northeast across
southwest Colorado. This is the disturbance that may lead to storms
moving across the forecast area this evening. Current radar and
satellite imagery show storms forming along the Front Range,
beginning to spread east onto the High Plains near the Denver and
Cheyenne, WY areas.

For this evening through tonight, attention is focused on what
may/may not come in from the west in terms of thunderstorm activity.
While convection has been developing along the Front Range, it does
not currently look visually impressive from radar or satellite
perspectives. Overall, the convection seems to be suffering from a
lack of substantial moisture to work with initially. As the storms
and disturbance move further east, there is more moisture and
instability to work with which may promote additional development
across eastern Colorado. Convective allowing models do indicate some
strengthening in current storms and further development, and storms
will also spread into Kansas and Nebraska...but not making it past
Highway 83 as daytime heating will be lost by the time storms make
it that far east. The main threats for these storms looks to be
damaging winds with large hail as a secondary threat. Inverted V
soundings as well as higher DCape would allow for a few
downbursts/strong convective outflows to occur. However, the severe
threat in general doesn`t appear to be too ominous and widespread
severe weather should not be anticipated at this time.

For tomorrow, moisture return is expected across the forecast area
with a few boundaries also taking shape...a dryline and cold front,
along with a surface low, should provide opportunities for storms to
develop east of Highway 25 during the afternoon hours. In addition,
storms should also develop over northern Colorado and spread across
the area generally along and north of Interstate 70. Overall, for
both areas of storm development, wind shear isn`t optimal...perhaps
30 kts or so of 0-6 km bulk shear. Moisture and instability is much
higher for the eastern area of development as this area will be east
of the dryline. Further west, instability may not be as high but
there is dry air to work with at the surface, which may allow for
cold pool formation and thus propagating MCSs. Therefore, there may
be two distinct rounds of convection...one forming along the
dryline/cold front east of Highway 83, and the second coming in from
the west/northwest and moving across the forecast area laying
along/north of Interstate 70. Damaging winds and large hail look to
be the primary threats. A tornado/landspout tornado can not be
totally ruled out, but this does not have the makings of a
significant tornado day. Afternoon high temperatures will be quite
warm, approaching or exceeding 90 degrees for many locations. Winds
should be lighter Tuesday compared to Monday, especially with the
center of the low moving through which should lead to a lull in the
light winds for most locations during the late morning to afternoon
hours. Unfortunately, these thunderstorms don`t seem to be heavy
rain makers expect for the few fortunate locations that may see two
rounds or slow moving thunderstorms initially in the event so
drought conditions won`t be significantly impacted from this event.

.LONG TERM...(Wednesday through Monday)
Issued at 230 PM MDT Mon May 16 2022

Similar to prior days this week, Wednesday will see another
shortwave trough come out of the central Rockies in the zonal flow
aloft, resulting in scattered afternoon and evening
thunderstorms. Models tending to favor the southwest and southern
parts of the forecast area for best chances. Instability is
forecast to be rather weak, but deep layer shear of 30-40 kts may
be sufficient for a marginal risk of a few severe storms on
Wednesday. High temperatures will be in the 80s and lows in the
50s.

Thursday will be the hot day of the period with southwesterly
downsloping winds both aloft and at the surface. Trended towards
warmer guidance and raised highs a bit to the lower to middle 90s,
maybe some upper 90s in typically hotter areas from McCook to
Hill City. Despite the warm temperatures, instability is very weak
and even then appears to be capped, so will keep it dry for
Thursday. However, critical fire weather conditions are currently
forecast for western half of the area and a watch may be needed.
As for winds, strongest winds will be in northeast Colorado where
mixed layer taps into about 40 kts, with lesser speeds in the
mixed layer further east. Rather potent cold front for late May
will move through Thursday night. May see some brief gusty winds
along/behind the front with pressure gradient. Low temperatures
Thursday night/Friday morning will range from the upper 30s in
northeast Colorado to around 50 in Hill City.

Friday will be much cooler with high temperatures in the 50s and
60s and breezy north winds. As upper trough moves through, will
see scattered showers develop first in northeast Colorado Friday
afternoon and rest of the area Friday night. Late Friday night,
may see rain mix with or change to snow along the Palmer Divide
area in northeast Colorado. However, not expecting accumulating
snow at this time. May need frost and freeze highlights for
Friday night/Saturday morning with lows currently forecast in the
lower 30s in northeast Colorado to around 40 in Hill City and all
areas well into the growing season.

For Saturday-Monday, currently expecting dry conditions and a
warming trend. However, GFS does show another trough moving
through Sunday night and Monday with precipitation chances, though
the ECMWF is dry. In fact, by Monday the GFS and ECMWF become
nearly out of phase with the upper pattern. Given the
discrepancies, low confidence in the latter periods, especially
with regards to precipitation chances. Temperatures will be below
normal on Saturday, near normal on Sunday, and slightly above
normal by Monday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 900 PM MDT Mon May 16 2022

KGLD...VFR conditions are expected through the period. A south
wind around 12kts at taf issuance will continue through 10z before
falling below 12kts from the south around 11z. Winds veer to the
west-southwest around 10kts by 16z then to the north at similar
speeds by 18z, continuing through 22z on the leading edge of the
dryline. After 23z winds veer to the northeast, occasionally
gusting over 20kts. Have introduced VCTS in the 02z-03z timeframe
as storms approach the terminal from the northwest. Severe weather
is possible with wind gusts over 50kts and large hail...at this
time latest HRRR shows the stronger wind gusts far enough away
from the terminal to prevent inclusion into the forecast but this
may change as we get closer to the event.

KMCK...VFR conditions are expected through 02z. A southeast wind
around 11kts at taf issuance will continue through 16z then veer
to the southwest at similar speeds through 18z then become light
and variable through 21z. From 22z-01 northeast winds around 10kts
are expected. From 02z-06z thunderstorms will be possible, moving
in from the west. Have added a PROB30 group for 02z-05z for wind
gusts to 45kts and 5SM -TSRA which becomes sub VFR conditions.
Current 00z HRRR has strong wind gusts than currently in the
forecast and severe weather is possible (hail and wind).

&&

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

$$

SHORT TERM...RRH
LONG TERM...024
AVIATION...99



Area Forecast Discussion

National Weather Service Green Bay WI

 1037 PM CDT Mon May 16 2022

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Tuesday
Issued at 250 PM CDT Mon May 16 2022

The latest RAP analysis and satellite/radar imagery show an upper
trough axis shifting east of the region from central Lake
Superior to eastern Lower Michigan. With the heat of the day, high
based fair weather clouds developed by mid and to late morning,
but area radars haven`t detected any shower activity so far today.
Deep mixing produced wind gusts up to 35 mph and the gusty winds
should continue into early this evening. As high pressure over the
northern Plains moves into the western Great Lakes, frost
potential and rain shower chances late tomorrow afternoon are the
primary forecast concerns.

Tonight...As the upper trough continues to slide further east and
away from the region, weak high pressure will be building over the
western Great Lakes. With cooling and a relaxing pressure
gradient, the gusty winds will subside through the evening.
Should also see clearing skies through the evening as well, which
will then lead to good radiational cooling conditions developing
across far northern WI. Statistical guidance shows lows falling
into the middle 30s across the northwoods, but stayed a degree or
two warmer in case winds didn`t subside as quickly in the evening.
Temps this cold will be cold enough for at least patchy if not
areas of frost. Lows to range from the middle 30s north to the
middle 40s south.

Tuesday...The morning will start out mostly sunny and quiet thanks
to high pressure across the region. Clouds will increase in the
afternoon ahead of shortwave impulses moving east across the
plains. Weak overrunning will shift east towards central WI by
late afternoon though most short range guidance keeps precip
chances further west by 7 pm. High temps will range from the lower
60s to near 70 degrees.

.LONG TERM...Tuesday Night Through Monday
Issued at 250 PM CDT Mon May 16 2022

Models still offer differing opinions on precipitation chances and
QPF as frontogenetic forcing and upper level jet energy moves
through the area Tuesday night into Wednesday morning. The GFS
still looks too aggressive, given that high pressure will still be
ridged over northeast WI. Suspect we will see only sprinkles or
light showers over the far north/northeast, with the best chances
occurring along and south of Hwy 29, where the strongest
frontogenetic forcing will set up. Could see a quarter to half
inch of rain in parts of central WI and the southern Fox Valley,
with amounts tapering off sharply farther north. Most of the rain
should end Friday morning, though a short-wave trough and
associated jet streak may bring a few showers or thunderstorms to
far northern WI late Wednesday afternoon and evening.

Scattered showers and thunderstorms may develop over northern WI
as a warm front approaches central WI Thursday afternoon and
evening. However, the best chance of rain should occur as a strong
cold front moves through late Thursday night into Friday morning.
Despite the less than ideal frontal timing, there is a risk of
severe storms given significant instability, moisture, strong deep
layer shear and forcing from the front and the RRQ of an upper
level jet. Locally heavy rainfall could also occur. The front
should shift out of the forecast area Friday afternoon.

Although no significant precipitation is expected over the
weekend, a short-wave trough may bring a chance of light showers
to the area Saturday into Saturday night. Generally dry conditions
are anticipated for Sunday, but there are differences of opinion
on whether precipitation chances will return on Monday.

Temperatures will start off a little below normal on Wednesday,
rebound into the upper 60s and 70s ahead of the cold front on
Thursday, then drop back below normal again by the weekend.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1036 PM CDT Mon May 16 2022

Mostly clear skies and good flying conditions can be expected
tonight into Tuesday morning as high pressure passes through the
area. Cloud cover will increase Tuesday afternoon into Tuesday
night as the next system approaches from the south. A few light
rain showers may also approach by mid to late Tuesday evening,
with the best chances at the souther TAF sites
(AUW,CWA,ATW,GRB/MTW) occurring toward the end of this TAF
issuance.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM.....MPC
LONG TERM......Kieckbusch
AVIATION.......Cooley



Area Forecast Discussion

National Weather Service Gray ME

 1104 PM EDT Mon May 16 2022

.SYNOPSIS...
Low pressure continues to track northeast tonight as a cold
front sweeps through the entire region overnight. Thunderstorms
will continue to develop this afternoon/evening and could
produce some strong to severe storms along the front, mainly in
New Hampshire. Temps turn cooler through mid week, before a
warming trend returns late in the week into the weekend with
increased ridging across Eastern Seaboard.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
1100 PM Update...
Have updated the near term portion of the forecast. Showers will
continue to exit the region over the next couple hours with
perhaps a rumble of thunder. Areas of fog will continue,
especially along and near the coastline.

Will continue to monitor rivers late this evening. The Pemy at
Woodstock continues to shower rapid rises.

904 PM Update...
Will be dropping the Severe Thunderstorm Watch with this
package. Although there may still be rumbles of thunder, the
precipitation continues to move through more stable areas. The
precipitation continues to overperform most models as rain is
reaching the coastline. Blended in the latest HRRR for pops over
the next several hours.

Areas of fog continue, especially near the coastline. This
continues to be picked up well by latest HREF probabilities.
Much of the fog will begin to dissipate after 07Z or 08Z.

Made some minor adjustments to temperatures, dew points,
visibilities and wind for the near term portion of the forecast.

Update...
Have updated the forecast to include Severe Thunderstorm Watch
number 231. Portions of New Hampshire will continue to have
strong to severe thunderstorms through about 02Z or 03Z. Have
included the threat of large hail and damaging winds in that
area.

Have expanded the fog forecast to the coast. Visibility down to
a quarter mile in Rockland with fog spreading to the southwest
coast of Maine and the New Hampshire Seacoast as well. The
latest HREF probabilities keeps this fog along the coast until
about 08Z.

Have made adjustments to the temperatures, dew point and winds
forecasts as well.

Prev Disc...
CAMS have been very good with the forecast this afternoon,
particularly the HRRR, Scattered convection continues to develop
in central and southern NH. These storm should lift N through
the state this afternoon before line of convection associated
with the cold front moves in. Also expect some scattered
convection to develop in the ME mtns late this afternoon. A few
storms are maintaining brief updrafts this afternoon, so a
couple warnings are not of out the question. Expecting ares S of
the Me mtns to stay dry until line comes through this evening.
As for the line, it current is looking fairly ragged and a bit
broken, so some concern how potent it will be when it crosses
into NH between 6 and 7 PM. But still some concern in the CT if
the line can get its act together. Once the line gets into ern
NH, should be weakening, but still will be able to produce some
lightning, so thunderstorms possible in ME through the evening.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Precip will end across the south after midnight, but
intensifying low N of ME, will keep showers going in the N,
especially in W ME. W flow should allow for some CAA to bring in
cooler and drier air, with lows in the 50s to around 60.

That low will shift slowly NE and will provide a couple round of
showers to the mtns, with partly sunny skies to the south. It
will be breezy with gusts to around 25 mph at times. Highs will
be in the 60s to low 70s.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Relief from the hot and humid conditions comes Wednesday as dry air
finally makes its way in for Wednesday morning as high pressure sets
in overhead under northwest flow.  Winds will stay breezy with gusts
up to 30 mph with highs in the upper 60`s in the south and upper 50s
in the north.  Relative humidity values look to fall into 20-25
percent in southern NH with relatively conservative dewpoints.  This
will be something to monitor as the breezy winds will help
contribute to near critical fire weather conditions.  Wednesday
night lows from the foot hills on west and north will dip down into
the mid 30s, it is expected to stay above freezing, but would not
rule out for the potential for some isolated areas of frost,
especially at elevations above 1000 feet.

Temperatures start building again for the second half of the week as
a warm front pushes north bringing the area into the warm sector of
a low making its way towards New England for the weekend. Several
models show some light rain passing over northern Maine and NH on
Thursday.  There is some disagreement on how long the dry air will
stay over the area which could limit precip chances so I have kept
PoPs at a chance for now.  Warm and humid air continues to build
into the weekend with temperatures peaking around 90 in southern NH
on Saturday.  Southerly flow will keep temperatures down along the
coasts keeping highs in the 70s for the immediate coast.  The warm
and humid conditions could lead to some diurnal storms developing
Saturday afternoon.  A cold front will be sweeping through the area
over the course of the day Sunday bringing widespread precipitation
as it passes.

Showers in the mtns continue into Tue evening, but
should wind down after midnight, although breezy conditions
continue overnight. Lows will be chilly,, from the upper 30s in
the mtns to the mid to upper 40s in the south.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Short Term...Areas of IFR and patchy LIFR conditions will
continue across the region in fog and precipitation. Conditions
improve overnight and into Tuesday to VFR. Winds become gusty
during the day Tuesday at all terminals. VFR conditions continue
Tuesday night.

Long Term....VFR conditions prevail with breezy NW winds Wednesday
and will continue through the end of the week as high pressure sets
in.  There could be another period of low ceilings on Thursday, but
any restrictions from Friday into the weekend would be expected
along the coast due to onshore winds returning.

&&

.MARINE...
Short Term...SCA extended into Tue night as a second surge of
cooler air and gusty winds moves over the waters. The persistent
fog should begin to dissipate late Tuesday night.

Long Term...Winds will quickly diminish from SCA levels on Wednesday,
however gusts will remain around 20-25 kts.  Winds will subside
Wednesday evening with calm seas remaining through the weekend.

&&

.FIRE WEATHER...
Breezy winds and low relative humidity values will set in early
Wednesday with gusts up to 30 mph and relative humidity dropping
to 20-25 percent in southern New Hampshire. This will approach
critical fire weather conditions. Status of green up, and how
much rain falls tonight, will help determine condition of fuels
for Wednesday.

&&

.TIDES/COASTAL FLOODING...
We continue to fast approach the highest astronomical tides of
the month. Tonight the astronomical tide will reach 11.4 feet
at midnight in Portland. A southerly winds increase this
evening, storm surge values may have a minor increase in value.
However, a southerly wind direction is not a preferred wind for
coastal flooding. Nevertheless, leaned towards a blend of ESTOFS
and ETSS storm surge values which bring up to a foot tonight as
ESTOFS itself appears to be high given the southerly set up.
This will bring up to a half foot of flooding to the wharfs and
backstreet in Portland, Granite Point Road in Biddeford and the
Backbay area of Hampton.

The late Monday into early Tuesday morning tide cycle (12:02
AM) to be the highest of the tide cycles. According to latest
surge guidance and latest anomaly data, tide gauges may approach
flood stage for Portland and points south.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Coastal Flood Advisory until 1 AM EDT Tuesday for MEZ023-024.
NH...Coastal Flood Advisory until 1 AM EDT Tuesday for NHZ014.
MARINE...Small Craft Advisory until 9 AM EDT Wednesday for ANZ150-152-
     154.

&&

$$
NEAR/SHORT TERM...Cannon
LONG TERM...Thunberg



...Updated Aviation Forecast Discussion...



 .DISCUSSION...
Issued at 309 PM CDT Mon May 16 2022

Quiet weather this afternoon with some fair weather cumulus and
highs in the upper 70s and lower 80s.

We`ll see a chance of showers and thunderstorms after midnight
tonight as the first of a shortwave moves into the area. Scattered
showers move down the Missouri River valley from northeast NE, and
possible into southeast NE as well.

Those spotty showers continue off/on Tuesday morning. But the
early afternoon, the thundershowers could become a little more
widespread across southeast NE and southwest IA. Much of the
forecast area remains in a slight risk of severe storms, which
should hold off until the late afternoon and evening. And it`s
then that various CAM solutions offering differing opinions. The
FV3, NAM Nest, and the NSSL WRF suggest southeast NE and southwest
IA have the greatest chances for severe storms, but the last
several runs of the long range HRRR suggest still want to force a
line of strong and possibly severe thunderstorms in northeast NE
that move through the forecast area through the night. The regular
HiRes ARW is somewhere in between. So there remains some
uncertainty about placement of severe storm chances tomorrow
afternoon and evening.

Whatever remains of the rain should be east of the area Wednesday
with dry conditions expected and above normal highs in the upper
70s and lower 80s still.

That dry weather continues into most of Thursday when
temperatures should rise into the mid to upper 80s ahead of the
next cold front poised to move into the region. That front reaches
northeast NE late Thursday afternoon, then moves through the
forecast area by daybreak Friday. Models remain in good agreement
with thunderstorm development along the front by Thursday evening,
with the best chances north of I80. The SPC Day 4 outlook from
earlier this morning placed portions of the Ohio River valley in a
probability of severe storms which is something we`ll continue
watch closely and further refine as we get closer.

This cold front sets the stage for Friday through Monday with
below normal temperatures. In fact, highs are only forecast to
reach the upper 50s/lower 60s Saturday, which is 13-17 degrees
below normal. And low temps could reach the upper 30s to lower 40s
Sunday morning. The will be a chance of showers mostly south of
I80 Friday night, but EC model trends continue to push this south,
but the GFS still maintains higher chances, so something we`ll
keep an eye on.

And forecast confidence by next Monday diminishes greatly as the
GFS has another decent short wave moving through the Plains, but
EC still has northwesterly flow, so no model consistency at all.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 604 PM CDT Mon May 16 2022

VFR conditions are expected through this TAF period with more
active weather expected just beyond. There could be a few hit and
miss showers and isolated thunderstorms across the region
throughout Tuesday morning however there is too much uncertainty
to include in the TAF at this time.

&&

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

$$

DISCUSSION...DeWald
AVIATION...Kern



Area Forecast Discussion UPDATED

National Weather Service Portland OR

 855 PM PDT Mon May 16 2022

...Evening update: for aviation weather.

.SYNOPSIS...Westerly flow aloft and surface high pressure will bring
seasonal conditions to the area Tuesday. The next weather system
reaches the coast late Tuesday night and moves inland Wednesday. The
result will be a return to a cooler and wetter pattern. Snow levels
lower to just below the Cascade passes Wednesday night. The yo-yo
pattern continues Friday and Saturday with warmer and drier
conditions.
&&

.SHORT TERM...(Tonight through Thursday)...At 20Z GOES-17 water vapor
revealed a broad upper level low pressure area in the Gulf of Alaska
extending southeast into the Pacific Northwest. A frontal boundary
was noted over eastern Washington and Oregon. Visible imagery showed
considerable lower level cloud cover over the forecast area. Finally,
KRTX doppler radar and ODOT webcams indicated
lingering isolated shower activity over the south Washington and
north Oregon Cascades and foothills. NAM Bufr soundings for KPDX
valid 22Z showed a subsidence inversion around 7000 ft.  Stable,
westerly flow aloft resides over the region Tuesday. The 12Z HREF
ensemble mean cloud cover guidance shows areas of low clouds over
the south Washington and far north Oregon coastal areas Tuesday
morning. These clouds are forecast to dissipate by late morning.
Otherwise, expect dry and slightly warmer conditions Tuesday. Model
850 mb temps warm around 3 deg C Tuesday. This result in max temps
close to seasonal norms. The dry period will be short-lived as the
next weather system moves into the region late Tuesday night and
Wednesday. Hi-Resolution convective allowing models (CAMS) shows
light rain reaching the south Washington and north Oregon Coast
between 06Z and 09Z Tuesday. The 12Z HRRR is a little slower, holding
it off until closer to 12Z.

This weather system will be fueled by a 120-140 kt jet. The bulk of
the dynamics Wednesday look to be directed at western Washington and
southwest British Columbia. The jet gradually sags south Wednesday
night. NAM 12-hr rainfall amounts through 18Z Wednesday are forecast
to be generally one-third to two-thirds of an inch for the coast and
associated higher terrain and the south Washington and north Oregon
Cascades. The National Blend of Models (NBM) 50th percentile 12-hr
amounts are a little less, around one-quarter to one-half inch in the
aforementioned areas and a tenth of an inch or less for the interior
valleys. Snow levels will be well above the Cascade passes Wednesday
morning, but lower to 3500 feet by late Wednesday night. The 12Z
deterministic NAM, GFS and ECMWF show a secondary 500 mb low pressure
area sliding southeast over the southern British Columbia coast late
Wednesday night and moving into southwest Washington by midday
Thursday. The NAM maintains a closed 500 mb low center as it rotates
inland while the ECMWF and GFS absorb it into the broad, upper level
trough. In any event, have opted to go with higher POPS Thursday.
Nearly all the EPS ensembles for KPDX and KKLS indicate some degree
of QPF Thursday. The 15Z SREF 12-hr calibrated thunderstorm product
yields a 10 percent contour from KPDX north Thursday afternoon. The
NBM Potential Thunder guidance is a little more robust, showing 15-20
percent probability north and east of a line from KSLE to KTMK. Have
not included thunder at this time, but next few shifts will want to
scrutinize this a little more. Weishaar

.LONG TERM...(Thursday night through Monday)...The broad and
expansive upper level trough migrates east Thursday night and Friday.
However, there are model differences regarding how fast this occurs.
The WPC cluster analyses valid 00Z Saturday are in general agreement
depicting the largest 500 mb negative height anomalies over the
Northern Plains (the Dakotas and far eastern Montana). Cluster 2,
comprised of about 25 percent EPS and GEFS members, holds
below-normal height anomalies more to the west with ridging further
offshore. Cluster 3, made up of nearly 50 percent CMC members, has
the upper ridge closer to the coast. There are a handful of EPS
ensemble members for KKLS that indicate light QPF Friday. This
forecast is geared closer to the NBM and NBM Experimental, suggesting
dry conditions.

The 12Z deterministic GFS appears to be an outlier, compared to the
corresponding ECMWF and the GEFS ensembles. The control run has a
weak 500 mb low sliding across the area Saturday morning, with the
upper ridge centered along 135W. There are only a few GEFS members
that depict this pattern. The ECMWF has ridging closer to the coast
with any short-wave energy dropping southeast through the northern
Intermountain Region as opposed to the Pac NW. The WPC clusters favor
ridging closer to the coast. Only Cluster 2, made up of nearly 60
percent GEFS, keeps the upper ridge axis west of 135W. Forecast
confidence lowers Sunday and Monday. The WPC clusters valid 00Z
Monday show more noticeable differences. Two of the four clusters
maintain ridging near or along the coast. Another cluster shows
flatter 500 mb flow with weak troughing along the Washington and
Canada border. The final cluster depicts ridging out near 140W with
some degree of troughing over the Pac NW. In a nutshell, kept close
to NBM output for Sunday and Monday. Weishaar

&&

.AVIATION...upcoming 06Z TAFS: Air mass stabilizing, with clouds
gradually flattening and dissipating. Still have onshore flow,
enough to maintain more moist shallow layer, roughly up to 2000 ft
above ground. This will contribute to forming of scattered pockets
of lower MVFR and possibly high end IFR (700 to 1500 ft0 CIGS from
10Z to 16Z Tue, but not enough to adversely impact most TAF sites.
Most like to see such CIGS would be KAST down to around KS12, and
then inland in the Cowlitz River Valley southward along the east
Willamette Valley and neighboring Cascade foothills valleys.
Otherwise, VFR. Will see the VFR deck of 5000 to 7000 ft gradually
thin apart overnight, but not completely go away until closer to
daybreak Tue.

VFR on Tuesday, with variable thin high clouds.

For detailed regional Pac NW aviation weather information, go online
to: https://weather.gov/zse

KPDX AND APPROACHES...VFR tonight, as the scattered to broken 7000
ft deck continues to gradually dissipate. While think should remain
VFR overnight into Tue am, suspect will see some patchy 0900 to 1500
ft clouds from 11Z to 16Z Tue, with broken of such between 13Z and
16Z. Otherwise, VFR on Tue, with variable thin clouds.   /Rockey

&&

.MARINE...Weak high pressure will slowly build over the waters
tonight into Tuesday. Seas should more or less hold steady during
this time. The next front will push into the waters Tuesday night
and will likely bring another round of high end Small Craft Advisory
to low end Gale Force wind gusts of 30 to 35 kt to the waters late
Tuesday night into early Wednesday morning. The strongest winds
appear likely to develop across the waters off the south Washington
and north Oregon coast with weaker wind across the waters off the
central coast of Oregon. Seas should respond accordingly and build
to at least 10 ft and become particularly steep and hazardous.

Models are coming into agreement high pressure should return to the
northeast Pacific late in the work week. This should bring a quieter
stretch of weather and allow seas to subside back below 5 ft towards
next weekend.

For those traveling in and out of the bars/harbors up and down the
Oregon and Washington coastline, we are in a strong to very strong
morning ebb cycle this week. /Neuman

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory from 4 AM to 8 AM PDT Tuesday for Columbia
     River Bar.

     Gale Watch from late Tuesday night through Wednesday morning
     for coastal waters from Cape Shoalwater WA to Cascade Head OR
     out 60 nm.

&&

$$

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