Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/20/20

Area Forecast Discussion

National Weather Service Marquette MI

 728 PM EDT Tue May 19 2020

.SHORT TERM...(This evening through Wednesday)
Issued at 337 PM EDT TUE MAY 19 2020

Water vapor imagery and RAP analysis indicate a rex-block pattern
taking shape over the central CONUS with models indicating a high
pressure ridge as the dominant feature over the next several days.
With dry conditions expected in the short term, this forecast will
focus on fire weather concerns and fine-tuning dew points, temps and
winds over the 24 hours of so.

Low 20s dewpoints over the eastern counties which prompted SPS for
elevated wildfire concerns have since recovered into the low 30s but
with temps rising into the mid to upper 60s, RHs are still in the 25
to 30 pct range. This along with e-se winds gusting aoa 20 knots
justifies the SPS.

Don`t think we will see the dramatic falling of dew points over the
eastern counties like we saw last night as winds should be a bit
more southeast than east. This should help limit advection of drier
air into region. Even so, might be just enough of a wind to result
in RH recovery to only around 70 pct east. Under clear skies, expect
lows across the area to dip into the 40s tonight, coolest over the
western interior.

Wednesday, upper-level ridging overhead will lead to dry and sunny
conditions. NAM model soundings depict mixing to somewhere around
3500 ft which along with 850 mb temps around 10C should support
highs well into the 70s. Suspect under clear skies mixing could
easily be 1 kft higher, so hedged warm on highs towards the 90th
percentile of model guidance. This gives highs in the mid 70s away
from the lakes to near 80 over the interior west. Temps will be
coolest right along Lake Michigan given the SE wind, whereas there
should be enough background synoptic flow to prevent the Lake
Superior lake breeze from making it inland much, if at all. This
deep mixing along with subsidence and low RH air aloft means low-
level moisture will likely mix out more than guidance shows. Brought
dew point down into the lower 30s which results in afternoon minimum
RH values to around 20% away from the lakeshores. Sustained winds of
10-15 mph and gusts to 20 mph will further increase the fire weather
risk but should still fall short of RFW criteria. Therefore, will
highlight the increased risk in the HWO with the idea that future
shifts should strongly consider an SPS.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 433 PM EDT TUE MAY 19 2020

Little change in the long-term period as North America remains in a
blocking pattern that is progged to continue until at least this
weekend. Upper Michigan looks to remain dry through at least Friday,
with two shortwaves progged to move through the UP Saturday into
Sunday. Deterministic models do show some agreement with respect to
one another; however, with any blocking pattern, solutions after the
blocking ends inherently have some spatial and temporal uncertainties
involved. As it stands now, the first chance for precip comes on
Saturday evening, with dry conditions expected Sunday, and a second
chance Sunday evening into Monday morning.

Wednesday night through Friday, high pressure off the New England
Coast will stretch a ridge of high pressure westward over Upper
Michigan through the end of the week. At the same time, an upper-
level cutoff low will linger across the Ohio River Valley. The end
result under this blocking pattern will be dry conditions with E to
SE winds prevailing. Expect high temperatures across the east and
downwind of Lake Michigan to be hindered with temperatures in the
downslope-favored Baraga Plains to have a few chances at hitting 80.
PWATs will be on the rise going into Thursday, but with the blocking
pattern and lingering high pressure I suspect the models were a
touch to fast increasing the moisture. I cut the Tds Wed night
through Thursday by roughly 10% or so by incorporating the GFS
mixing heights.

For Friday night heading into the weekend, models are still
relatively similar as they have been the last day or so. The
question remains how are they handling this blocking pattern that we
are in? As a shrtwv trof moves through Saturday evening, this will
bring the first legitimate chance at precipitation of the period.
Models show some indication of this wave slowing down, or perhaps
not quite bringing the precip here. The next chance, which looks a
little better and brings with it the chance for thunderstorms
arrives on Sunday evening into Monday. However, this is where the EC
and GFS start to show their discrepancies. Given these uncertainties
have capped all PoPs in the extended at 50% until some more
certainty is shown.
&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 727 PM EDT TUE MAY 19 2020

Low-level dry air will mostly linger thru this fcst period, allowing
VFR conditions to prevail at KIWD/KCMX/KSAW. However, area of lower
clouds, including MVFR cigs, over central and southern WI will lift
nw tonight. Some of these lower clouds should arrive at KIWD late
tonight thru Wed morning, but there is uncertainty on coverage and
also on cloud base height. For now, kept mention at KIWD to few at
3000ft.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 337 PM EDT TUE MAY 19 2020

Blocked upper level pattern will continue with little movement to
surface systems through much of the week. Surface high pressure will
generally dominate across the region, keeping the wind to less than
20 knots through the entire forecast period.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...Voss
LONG TERM...JAW
AVIATION...Rolfson
MARINE...Voss



Area Forecast Discussion

National Weather Service Pocatello ID

 839 PM MDT Tue May 19 2020

.UPDATE...Will issue an update this evening to decrease Min Temps
tonight a bit for much of the area. For areas where the precip has
allowed for evaporated cooling, several spots were already near
or at their min temp. Feel that the overcast cloud deck won`t
allow for too much more cooling though. There may even be a little
bit of warming temperature where the downslope wind kicks in
overnight for a few spots.

ND
&&

.PREV DISCUSSION... /issued 152 PM MDT Tue May 19 2020/

SHORT TERM...Tonight through Thursday. Showers and thunderstorms
will gradually increase in coverage as the low lifts northeast
across the state through tomorrow. There is a risk of
strong/isolated severe thunderstorms through this evening,
especially over the central mountains where SPC has expanded the
Marginal risk area today. In reality, any storm today could easily
produce strong winds over 40 mph and/or small hail. Outside of
showers and storms there could be some gusty winds at times
overall. There might be a better chance tomorrow across the Snake
Plain, where localized blowing dust might occur. Snow levels
still drop to near 7000-7500ft across the Sawtooths southern
highlands, while they will be closer to 8000-8500ft near Island
Park and the Wyoming border. We could see some brief accumulations
in the Stanley Basin and on our highest summits, but impacts will
not be widespread or last too long as melting will eventually
take over. If you are venturing to our highest peaks, then you
will need to worry about having winter gear as some lingering
accumulations are possible.

For tomorrow night and Thursday, we will be in between storms.
Lingering showers and possible thunderstorms are forecast across
the mountains, especially the Sawtooths and east of I-15. Snow
levels will be lower overall, 6500-7500ft, Thursday morning. Trace
amounts of snow are possible down to those levels, but again
nothing impactful is anticipated. Winds will be gusty in the
afternoon, but lower than Wednesday so any impacts would be very
isolated.  Keyes

LONG TERM...FRIDAY THROUGH NEXT TUESDAY...
Fri continues to look quite wet as a pronounced shortwave rotates
into the area with an attendant cold front progged for Fri eve.
Instability should be somewhat hampered by high temps only making it
into the upper 40s/mid 50s, but based on the favorable diurnal
timing of the front and upper-level dynamics, will continue to carry
mention of thunder with no severe wx currently expected. QPF amounts
in excess of 1/2 inch will be possible across the srn/ern highlands
into the Island Park region, with a couple inches of snow possible
above 6,000-7,000 feet CWA-wide with those colder temps. At this
time accumulations should remain high enough in elevation to avoid
any major impacts to travel, even at the passes. A few showers/t-
storms may linger Sat, esp in the mntns. We`ll also have to keep an
eye on how much skies clear Sat AM, as any clearing may allow temps
to fall into the low 30s with the risk for frost just about
everywhere. Long-range models continue to run very dry for Sun/Mon
with a broad ridge of high pres taking control. NBM guidance remains
a bit sluggish to catch up and continues to carry PoPs each day, so
we again trimmed these back to better mirror the GFS/ECMWF/Canadian
consensus. Confidence in this drier solution is growing with decent
run-to-run consistency. A better signal for clearing Sun AM means
another round of frost possible. A warming trend is also expected to
start Sun afternoon, with 70s returning to lower elevations by Mon.
Tues, the warming trend continues, and models advertise varying
degrees of longwave troughing returning across the nrn Rockies. It
remains to be seen whether or not this feature will produce much
precip, but it does appear to be much more progressive and short-
lived compared to the stagnant cool/unsettled patterns we have
frequently found ourselves in over the past few weeks. - KSmith

AVIATION...This afternoon will not be as breezy as yesterday, but based on
projected downslope flow advertised on HRRR guidance and how well
this performed yesterday, we continue to carry 20G30kts at KPIH out
of the S/SW (higher than MOS guidance). Elsewhere, while winds have
decreased since yesterday, potential for TS has increased with high-
res HREF ensemble members generating some pretty widespread activity
after 20-21z along and west of the I-15 corridor (KPIH/KIDA),
possibly lingering until midnight or later. Potential for a TS to
hit a terminal is definitely there for KPIH/KIDA/KBYI/KSUN, but with
a few differences noted between different high-res reflectivity
projections and the fact that most of the activity doesn`t exist
yet, we continued to blanket VCTS and will have to closely monitor
observational trends for the need to amend. Decent low-level
moisture may take the edge off downdraft efficiency today compared
to yesterday, but a few stronger storms could still squeak out small
hail or erratic wind gusts. Main focus tonight will be cigs, as
guidance trends all sites toward MVFR over the course of the night.
At this time, greatest concern for BKN or better MVFR cigs is at
KBYI/KSUN after 07-09z. We leaned into this potential in the TAFs,
but will need to monitor trends in case cigs try to nudge lower,
which is possible given nocturnal precip in the area. At this time
IFR conditions remain unlikely. In general expect a repeat
performance Wed with breezy conditions and showers/storms. -
KSmith

FIRE WEATHER...Showers and thunderstorms will spread eastward over
the next two days and expand in coverage. The unsettled weather
continues through at least Sat evening, then high pressure returns
for Sun through Mon, at a minimum. The low coming in will bring its
cold core over the central Idaho mountains by Wed; this air is cold
enough to bring snow back to the higher elevations, mostly above
7500ft. Farther south is a lower concern, as the air is warmer and
the terrain is lower. Temperatures will be on a cooling trend
through Fri, then as the low slowly departs Sat night, skies will
start clearing and temperatures will warm. With cool temperatures
and abundant precipitation, humidity will remain high. With the
approaching low, wind will be breezy to windy, but not as strong as
Mon wind. Wind will continue to be at least breezy (10-20 mph)
through Fri. Messick

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$




Area Forecast Discussion

National Weather Service Pueblo CO

 856 PM MDT Tue May 19 2020

.UPDATE...
Issued at 854 PM MDT Tue May 19 2020

Quick refresh for the gridded forecast database. Brought in
latest high res dewpoints and winds, as well as incorporating obs
data. Moore

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 300 PM MDT Tue May 19 2020

The current Red Flag Warning that is in effect until 8 PM still
looks good, as conditions this afternoon are meeting the criteria in
those locations.

So far this afternoon, there have been some echoes on radar over the
mtns but haven`t seen any lightning yet.  SPC mesoanalysis shows
1000-about 2500 J/kg of CAPE over the eastern plains, but there`s
still some CIN over the far southeast plains.  Still expecting some
thunderstorms to develop this afternoon/early evening over the mtns,
high valleys, and I-25 corridor, then spreading east in the evening.
There could be a couple strong or severe storms over the plains this
evening.  Some of the forecast models are showing the potential for
some lingering showers/tstms over and near some of the eastern mtns
into the late night hours, with the HRRR and NAM showing the best
chances being over Teller and El Paso Counties. The NAM and GFS also
show the potential for low stratus tonight over portions of the
eastern plains, especially the far eastern areas and El Paso County.

Wednesday continues to look like a day with widespread fire weather
concerns.  There is already a Red Flag Warning in effect and the
current area of concern and the time-frame of concern (11 AM through
9 PM) should be ok.  It looks fairly windy over most/all of southern
CO Wed.  Forecast models differ a bit with regards to dew points
across portions of the plains Wed afternoon, and there is a chance
that Crowley, Otero and eastern Las Animas Counties may not see low
enough RH values to meet red flag criteria, but at this time there
is too much uncertainty to make changes to the fire weather
highlight.

The other concern for Wed is the chances for thunderstorms and
severe weather.  The forecast models keep western areas dry Wed
afternoon, with the NAM keeping all of southern CO dry, and the GFS
developing storms over the far southeast plains after 3 PM, and the
ECMWF showing precip over the central mtns and mostly the far
southeast plains.  If anything does fire up, there is expected to be
a decent amount of CAPE over the far southeast plains, with a narrow
ribbon of 2500-3000 J/kg from about the Limon area south through
Bent County and along the Las Animas and Baca County border, with 0-
6 km shear of around 35 kts.  SPC has a Marginal risk of severe
storms over much of the southeast plains for Wed.  Large hail and
strong wind gusts will be the main severe concerns.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 300 PM MDT Tue May 19 2020

Wednesday night...The potential for convection continues across
portions of the plains into the overnight hours. CAPE and bulk shear
values are expected to be sufficient for a strong to severe storm as
noted in the short term discussion, but a healthy cap is also
expected be in place east of the dry line, which could hinder
additional thunderstorm development. As the sun sets and the dry
line retreats back to the west, this cap is expected to follow.
Therefore, the chances for thunderstorm development diminish after
sunset. If there is any ongoing convection, it is anticipated to
move eastward through the overnight hours.

Thursday...The upper-level trough axis is expected to move into
Colorado during the day, which is anticipated to send a cold front
through the plains during the morning hours. Easterly post-frontal
surface flow is anticipated to develop, bringing some return flow
moisture to the plains, increasing the instability. There is some
disagreement between models just how much instability will be
available, but general consensus is that there will be at least 1000-
1500 J/kg of CAPE, with the highest values situated over the far
southeastern corner of Colorado. Guidance is also indicating bulk
shear values should be in the 40-50 knot range, resulting in the
potential for severe thunderstorms. With less of a cap expected to
be in place, Thursday appears to have a better chance for severe
weather. As such, the Storm Prediction Center does have a Slight
Risk out for the far southeastern corner of the state. Currently,
the primary threats with storms on Thursday appear to be wind and
hail. Elsewhere, warm and dry conditions are expected to continue
over the San Luis Valley, bringing potential for near critical fire
weather conditions once again. As of right now, winds reaching the
critical threshold remain in question, so have decided not to issue
any highlights at this time.

Friday into Tuesday...Another upper-level trough is expected to dig
south from the Pacific Northwest, but is not anticipated to dig as
far south as the previous trough. Southwest flow ahead of this
trough will likely bring critical fire weather conditions to the
region on Friday and Saturday before a cold front moves across the
region on Saturday. A trailing upper-level trough is expected to
move through Colorado on Sunday into the southern Great Plains,
bringing an increased chance for precipitation to the area Sunday
into Monday. Precipitation chances diminish for Tuesday as the upper-
level trough drifts eastward.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 300 PM MDT Tue May 19 2020

Gusty southerly winds can be expected into the evening hours at
KCOS, KPUB and KALS, with winds then decreasing, but probably
increasing again through the morning hours on Wed, with windy
southern winds through Wed afternoon and into the evening. KCOS and
KPUB could see thunderstorms in the vicinity through about 02Z, but
there is a small chance the KCOS could see some thunderstorms in the
vicinity through around 06Z.  Later tonight, there could be some low
stratus clouds at KCOS and KPUB which could cause MVFR or IFR CIGS.
At this time it appears that chances are low, but KCOS and KPUB
could see some thunderstorms in the vicinity late Wed afternoon.


&&

.PUB WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 11 AM to 9 PM MDT Wednesday for COZ220>233.

&&

$$

UPDATE...MOORE
SHORT TERM...28
LONG TERM...CARLBERG
AVIATION...28



Area Forecast Discussion

National Weather Service Sacramento CA

 309 PM PDT Tue May 19 2020

.Synopsis...
Showers and isolated thunderstorms linger into the evening,
mainly for the mountains and foothills. Snow above 7000 feet may
cause travel delays. Dry weather and a warming trend are expected
from mid-week onward, with above normal temperatures by the
weekend.

&&

.DISCUSSION...
The upper level low that has brought active weather continues to
make its journey to the east this afternoon. It is still bringing
shower activity to the region though and we are seeing showers
on radar over the mountains and upper foothills. SPC Meso Analysis
has about 100-250 j/kg of CAPE over much of NorCal. Model
soundings are pretty unimpressive with long and very thin CAPE
profiles. Giving that information the thunderstorm threat will be
pretty low this afternoon/evening but can`t completely rule out
the chance. Still quite a bit of moisture in the area with Pwats
greater than 0.50", brief heavy rain can be expected with any of
the more intense showers. The HRRR has been pretty consistent on a
few showers pushing over the southern Sac Valley into the
northern San Joaquin late afternoon into the evening. Its run to
run consistency was enough for me to add just a slight chance for
showers KMYV south but overall should be a dry evening for the
valley. Snow levels into the evening will be around 7000 feet and
intense snow will be possible under any of the showers. The
majority of the showers will diminish by 3z/7 pm but will linger
over the mountains as a weak wave pushes south over the Sierra.

The trough will be pushing into the four corners region on
Wednesday with upper level riding building into NorCal. Still
could see a shower or two pop up for the first half of Wednesday
on the mountain crest but overall dry weather is expected. Short
wave ridging will remain in place for Thursday. A trough will be
digging to our east on Friday. No precip is expected with this
trough but we will see enhanced northerly flow.

Below normal highs will be replace with near normal highs the rest
of the week.

-CJM

&&

.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...
Upper level ridging is going to build in for the Holiday weekend
and will continue into early next week. This will bring quiet
weather but it will start to feel more like summer. Highs will
start out in the 80s Saturday in the valley and will climb back
into the 90s Sunday and will push into the mid to upper 90s early
next week. This will bring an elevated heat risk to the region.

-CJM

&&

.AVIATION...
VFR conditions over interior NorCal next 24 hours except for
local MVFR/IFR with isolated LIFR in showers, mainly over the
foothills/mountains. Isolated thunderstorms possible through 03z
Wednesday. Surface winds generally below 12 kts at TAF sites.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 5 PM PDT this afternoon for West
Slope Northern Sierra Nevada.

&&

$$