Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/21/20

Area Forecast Discussion

National Weather Service La Crosse WI

 1049 PM CDT Sat Jun 20 2020

.SHORT TERM...(This evening through Sunday)
Issued at 246 PM CDT Sat Jun 20 2020

Afternoon water vapor imagery reveals a vigorous shortwave advancing
through southern Minnesota. A weak surface low reflection was
present over southwest Wisconsin, with the quasi-stationary front
still hanging out over our far southern counties, stretching from
southwest Iowa to the eastern UP. Widespread morning cloud cover has
given way to some breaks in the clouds over much of the area, with
some clearing on our western doorstep. Today`s cloud cover and
earlier rain has kept temperatures on the cool side once again,
ranging from the mid 60s to mid 70s across most of the area as of
2PM. Dewpoints remain in the 60s to low 70s, highest near and south
of the front. With the breaks in the clouds, instability has been
increasing over the last few hours, especially south of I-90 where
MLCAPE has climbed to 500 to 1000 J/kg per RAP analysis. There is 40
to 50 knots of 0-6km shear associated with that incoming shortwave,
but this only favorably overlaps the instability this afternoon
across a small portion of the area, generally northeast Iowa into
far southwest WI. This area near the boundary will be the area to
watch through early evening for the greatest potential for storms,
perhaps a few on the strong side.

Main threats with stronger storms through early evening will be
locally gusty winds and perhaps some small hail. Can`t rule out a
funnel cloud or two along the boundary given weak low level wind
fields in place. And as we`ve seen lately, they will also be
efficient rainers with PWATs >1.5" and warm cloud depths >3500
meters. CAMs show the activity progressive enough to suggest a lower
threat for any flood potential, but will have to watch where this
activity becomes focused, given a long, broad swath of 1 to 2+"
antecedent rainfall since last night from Chickasaw County all
the way to northeast WI. If storms repeat over this area, could
see localized exceedance of flash flood guidance.

Guidance in good agreement with the focus for rainfall largely
diminishing and exiting the area by early evening, though isolated
convection may linger through around midnight. Skies will partially
clear from the west tonight with continued light winds. Given the
abundant low level moisture and recent rainfall, looks like a decent
setup for fog development, especially near and east of the
Mississippi River. Not a slam dunk fog forecast given some breezy
winds developing just off the surface late tonight, but the general
setup certainly looks plausible. Lows in the 50s to low 60s.

Sunday starts out with some sunshine and a southwesterly breeze,
which will promote much warmer temps than we`ve seen the past couple
days. Clouds will spread in during the afternoon as another
shortwave approaches, bringing the next round of showers and storms
to the area. The warmer temps will foster greater instability with
MLCAPE of 1000-2000 J/kg possible west of the Mississippi. Looks
like meager deep layer shear of barely 30 knots, but conditions will
be a little more favorable just upstream so will need to keep an eye
on how things evolve as the convection approaches. CAMS seem to each
have their own idea of exactly how this will evolve, but as of now
timing for our area generally appears focused on Sunday evening and
SPC has expanded their day 2 convective outlook eastward into our
western half (more below).

.LONG TERM...(Sunday night through Saturday)
Issued at 246 PM CDT Sat Jun 20 2020

The active weather pattern will continue as an approaching shortwave
trough drives a cold front across the area Sunday night into Monday
with associated thunderstorm chances. On Sunday evening/night,
boundary parallel deep layer shear around 30-35 kts may lead to
upscaling of storms into the area from the north and west along the
front, with some potential for a few strong or severe storms. Deep
warm cloud depths, high pwats, and moisture transport/plenty of
MUCAPE ahead of the boundary would support a heavy rain threat with
the storms. The timing of the front and degree of destabilization
will help determine the severe weather threat on Monday as a
stronger upper trough approaches. Guidance remains somewhat at odds
with the speed of the front, which may be impacted by the evolution
of earlier convection, but a slower passage could increase potential
for stronger storms at least for southern areas on Monday afternoon.

Northwest flow develops behind the front into mid-week with a drier
airmass and comfortable high temps in the 70s. There will still be
some shower/storm chances around as weak shortwaves rotate through
the longwave trough/cool pool aloft.

Late in the week the flow pattern loses amplitude with a few
shortwave troughs possibly impacting the area. Gradually warming
temps are expected, but predictability is low with timing of precip
chances in this pattern.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1051 PM CDT Sat Jun 20 2020

Patchy to areas of fog are possible tonight across western and
central Wisconsin, which could impact KLSE late tonight. If
clouds clear completely at KLSE, MVFR conditions in BR can be
expected and cannot rule out brief IFR conditions in FG. Showers
and thunderstorms look to impact both TAF sites tomorrow evening
with periods of MVFR to IFR conditions possible. A few
thunderstorms may also produce gusty winds tomorrow evening.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&

$$

SHORT TERM...Kurz
LONG TERM...JM
AVIATION...Wetenkamp



Area Forecast Discussion

National Weather Service State College PA

 1131 PM EDT Sat Jun 20 2020

.SYNOPSIS...
Little change to our current weather pattern is expected
through the first half of the upcoming week. Warm and
relatively humid conditions will combine with a pool of cool
air aloft to fuel scattered to numerous afternoon and early
evening showers and thunderstorms. Any thunderstorms are
expected to remain below severe limits, but they may produce
locally heavy downpours and their slow-moving nature could
lead localized flooding of poor drainage areas.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
7 pm update... Showers and thunderstorms have begun to diminish
in coverage early this evening, with that trend expected to
continue through the evening as we lose daytime heating and
stabilize the environment. Locally heavy rainfall (isolated
point totals of 2.5-3.5" in about a 90-minute period) was again
the main culprit through the afternoon and early evening hours.

Later tonight, as showers become quite isolated, areas of
stratus and fog should develop once again, within a very moist
boundary layer with light flow.

Lows by daybreak will range from the upper 50s over parts of the
Alleghenies to the mid 60s in the Middle and Lower Susquehanna
Valleys.

Previous discussion... Numerous showers and scattered TSRA were
rapidly developing across the southern third of the state and
drifting slowly to the north and NW across the CWA, beneath the
mid and upper level thermal trough.

Similar convective evolution with respect to timing of
initiation and the areal coverage of convection is expect this
afternoon. Sfc based cape is lagging friday though, by a few to
several hundred j/kg as low cloud cover and fog was more
extensive and thicker this morning.

17Z run of the HRRR and the 12Z HREF favors the greatest amount
of SHRA/TSRA across the Lower Susq Valley (and Laurel
Highlands) through 21Z, then outflow boundaries and newly
ramped up sfc cape values help to shift the main threat for rain
to a corridor from Scent PA to the Middle and West Branch Susq
Valley late this afternoon and early this evening.

The pulse and transient multi-cell nature of the convection will
afford little organized training for heavy rain, though
some locations that experience a few TSRA could end up with over
one inch of rain - which is still comfortably below 1 and 3
hour flash flood guidance of 1-1.5 inches and 2.5-3.5 inches
respectively.

mid afternoon temps are quite similar to Fri, and perhaps a bit
across the NW. Highs will range from the low to mid 70s over
much of the Laurels, to the low 80s across the Middle Susq
Valley.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
1030 pm Sunday update... No substantial forecast changes were
noted during this period from the previous update.

On Sunday, the pesky cutoff low and shear axis extending
northward is expected to edge eastward towards the coastal
plain. As a result, although afternoon/early evening convection
is again expected, coverage should be a bit less than the last
couple of days (more hit and miss) and also centered a little
farther east (more across our Susquehanna Valley zones).

Given slightly building heights aloft as well, afternoon highs
should be a few degrees above those of Saturday (highs generally
in the 80-85 range).

By Monday, although the aforementioned cutoff low should be even
less of an influence, we should see some height falls edge into
the Commonwealth from west-east, with a weak surface front
pushing towards the eastern Great Lakes region. Proximity of
these two features should lead to a resurgence again of
diurnally enhanced showers and thunderstorms.

Previous discussion... Loss of sunlight on this, the longest
day, will allow for fizzle quickly this evening. Fog and low
stratus is expected once again tonight/Sun AM in the areas where
it rains this aftn and evening.

The center/axis of the upper low should be to the east of the
area on Sunday, but a weakness/trof will lag back to the west.
This makes it possible for a repeat of our daily shot of diurnal
convection.

Less forcing means perhaps even more-scattered/isolated
convection than Sat. However, the overall pattern does shift in
an additional way for Sunday. A long-wave trough approaches from
the west. Shortwave troughiness may meet up in good timing to
enhance things, or miss timing and have a quieter day since
there might be a tiny bit of ridging overhead.

High temps Sunday appear to be a few degrees warmer in many
locations, though the Laurels could see a jump in max temps by 5
to 8 deg F.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Medium range guidance pushes a cold front through the region
either Tuesday night or early Wednesday in association with
approaching upper level trough. This timing supports likely
convection across the western half of the state Tuesday PM, with
the focus of showers/storms shifting to southeast Pa Wednesday.

After a long stretch of warm/humid conditions, the latest NAEFS
and ECENS both support a return to near seasonal temperatures
and much lower chances of rain late next week (finally providing
a break in the daily tstm activity), as surface ridging builds
in behind cold front. However, passage of upper trough justifies
maintaining low POPs of a PM shower/storm Thursday and Friday.

&&

.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
Isolated convection is quickly dissipating this evening with the
loss of daytime heating. With light winds, we will likely see
low clouds and fog develop again overnight, especially in areas
that received rain today.

Fog will dissipate and low clouds will lift and scatter out by
mid to late morning Sun. The rest of the day should be partly
sunny. A few stray showers may develop by late afternoon or
early evening, but showers should be much less numerous than
they were Fri or Sat.

Outlook...

Mon...AM low cigs/showers possible NW Mtns. Isolated PM tsra
impacts possible.

Tue...AM low cigs possible N Mtns. Scattered PM tsra impacts
possible.

Wed...AM low cigs/fog possible W Mtns. Isolated PM tsra impacts
possible southeast Pa.

Thu...AM low cigs/fog possible. Mainly VFR PM.

&&

.CLIMATE...
Astronomical summer began at 5:43 p.m. on Saturday, June 20.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...Lambert
NEAR TERM...Jurewicz/Lambert
SHORT TERM...Jurewicz/Lambert/RXR
LONG TERM...RXR/Colbert
AVIATION...Colbert
CLIMATE...Lambert



Area Forecast Discussion

National Weather Service Goodland KS

 450 PM MDT Sat Jun 20 2020

.SHORT TERM...(This evening through Sunday)
Issued at 240 PM MDT Sat Jun 20 2020

Overview: Cyclonic flow aloft (assoc/w a broad upper trough over
the Central/Northern CONUS) will prevail today -- transitioning to
NW flow aloft on Sunday.

Through Tonight: Simulated reflectivity forecasts via the HRRR and
NAM NEST suggest that broad cyclonic flow aloft, DPVA attendant a
small amplitude wave therein (progressing eastward from CO into
Western KS), weak low-level convergence invof a modest dryline,
and a moderately unstable airmass characterized by 1500-2000 J/kg
mlcape -- will foster the development of isolated convection
along/south of I-70 by 21-23Z, though development may be more
likely invof a line extending from Tribune-Gove City-Hill City --
where a relatively robust Cu field is already evident via visible
satellite imagery. While modest (20-30 kt) effective deep layer
shear suggests multicellular organization (initially, at least) --
the presence of (1) moderate instability and (2) strengthening
deep layer shear later this afternoon (30-40 kt by ~00Z) --
appears supportive of supercells. With this in mind, an isolated
potential for severe hail and damaging winds will exist late this
afternoon, mainly between 22-02Z along/south of a line from
Tribune-Gove City-Hill City where deeper low-level moisture
(10-12C H85 dewpoints) is more likely to foster deep/established
updrafts.

Sun-Sun Night: Small amplitude shortwave energy progressing
ashore the PAC NW this aft/eve is progged to track ESE-SE through
the Northern Rockies (tonight) into the Central Plains (Sunday).
Simulated reflectivity forecasts via the HRRR/NAM NEST suggest
that DPVA attendant the aforementioned shortwave energy and low-
level convergence invof a SSW-NNE oriented dryline will aid in
convective development by early-mid afternoon (~20Z) -- somewhere
along/east of a line from Leoti-Oakley-Oberline -- with activity
growing upscale into a squall line /MCS/ that progresses southeast
into South-Central KS (late afternoon) and Northern OK (evening).
Steep mid-level lapse rates (8-8.5 C/km) and rich low-level
moisture on the eastern periphery of the dryline will foster
strong diurnal destabilization (2500-3500 J/kg mlcape).. amidst
strong (1300-1600 J/kg) dcape and modest (25-35 kt) deep layer
shear. Though discrete updrafts may briefly be present at onset,
rapid upscale growth along a consolidating cold pool suggests that
damaging winds will be the primary hazard, with destructive
straight-line winds possible as the MCS matures and propagates
downstream into South-Central KS and Northern OK during the late
aft/eve.

.LONG TERM...(Monday through Saturday)
Issued at 203 PM MDT Sat Jun 20 2020

At the start of the forecast period, an upper trough will be
centered over Nebraska and the Dakotas as it continues on its
eastward progression across the northern half of the nation. The
Tri-State area will be under northwest flow aloft with an upper
ridge over the Western CONUS. Temperatures on Monday will be in
the mid-80s in the northern part of the Tri-State area and the
upper 80s to low 90s in the southern part. A trough on the lee
side of the Rockies will provide some lift in the region which
could help in shower and thunderstorm development in the afternoon
and evening hours. At the moment, CAPE values appear to be low
and lapse rates are not looking all that great. Severe weather is
not anticipated with any storms that develop at this time.

A cold front will swing south, into the Central High Plains
through the day on Tuesday. Cooler air filtering in behind the
front will cool our temperatures down a few degrees. High
temperatures will range from the upper 70s to mid-80s. A few
showers and thunderstorms may be possible.

A gradual warming trend will begin Wednesday, continuing into the
weekend. A flattening ridge will move over the Rockies and into
the Central High Plains through the week. As the ridge moves over
the area, flow will become zonal across the Tri-State area. A
closed upper low will be in place over the Great Lakes for much of
the week, eventually beginning to move off to the northeast on
Thursday as another upper trough pushes eastward over the Western
CONUS. The GFS and ECMWF continue to disagree on the timing of the
progression of the closed low with the ECMWF having the more
aggressive ejection northeastward.

The lee trough over Eastern Colorado will remain in place through
Friday before lifting to the northeast, across Nebraska on
Friday. Models are suggesting a closed low developing at the 850mb
level as the system moves out of the area. Shower and
thunderstorm chances are possible each day, though confidence
remains low on area coverage, so have opted to keep PoPs low for
the time being. Temperatures heading into the weekend will return
to the low to mid- 90s for highs and the low to mid-60s for lows.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 450 PM MDT Sat Jun 20 2020

For KGLD and KMCK, vfr conditions expected through the period.
Southerly winds 10kts or less at taf issuance will continue
overnight then steadily veer to the southwest at similar speeds
Sunday morning then west in the 15z-18z timeframe. For the
afternoon winds continue to veer to the northwest and approach
12kts in the latter half of the afternoon. At this time any
convection will be east of the terminals Sunday afternoon.

&&

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

$$

SHORT TERM...VINCENT
LONG TERM...AW
AVIATION...99



Area Forecast Discussion

National Weather Service Northern Indiana

 746 PM EDT Sat Jun 20 2020

.SYNOPSIS...
Issued at 746 PM EDT Sat Jun 20 2020

A few showers are expected through early tonight, primarily along
and west of US 31. Look for an increase in the chances for showers
and thunderstorms Sunday afternoon, with even more numerous
showers and storms Monday into Tuesday. Highs will remain in the
80s with lows generally in the 65 to 70 degree range through
Tuesday, then a bit cooler and less humid for the remainder of the
workweek ahead.

&&

.SHORT TERM...(This Evening through Sunday)
Issued at 216 PM EDT Sat Jun 20 2020

Latest RAP analysis has 500mb ridge axis over the area this
afternoon as water vapor imagery showing eastward shift of upper
low to the mid-Atlantic region. Focus in the short term will be on
short wave energy ejecting out of the central plains from the
base of closed low centered over Manitoba along with associated
surface frontal wave moving out of Iowa. Best chances for
organized convection will be to our west in more favorable
unstable environment and aided by forcing from aforementioned
synoptic features. As pointed out in previous
discussion...antecedent dry/drought conditions hampering weak SW
flow from increasing boundary layer moisture. Latest HRRR forecast
soundings once again showing afternoon mixing increasing dew
point depressions over the next few hours dropping dewpoints into
the mid 50s. This will limit diurnal instability going into the
evening hours and confine chance PoPs to western CWA tonight.
Similar setup for Sunday but with a little better moisture return
ahead of slow moving cold front. This should prevent dewpoints
from mixing out and thereby provide better afternoon instability
and better chances for showers and thunderstorms.

&&

.LONG TERM...(Sunday Night through Saturday)
Issued at 216 PM EDT Sat Jun 20 2020

Forecast period to begin with longwave trough axis shifting
eastward toward the great lakes region. Short wave energy ejecting
out ahead of this will bring some modest forcing into the region
and will combine with a little better moisture return on SW flow
in the low levels. The added low level moisture will result in
better instability with CAPES reaching 2000J/kg across much of the
area. Still an overall weak flow/low shear environment so expect
scattered discreet to multi-cluster storms popping up Monday
afternoon that could transition into a more organized linear mode
Monday night into Tuesday morning as cold front approaches from
the west. Strong signal among the ensemble members centered around
Monday night so likely/cat PoPs are in order. Upper low then
settles into southern Ontario mid week as cold front continues to
push south into the TN valley bringing cooler but still seasonable
temps to the region and generally dry weather through the end of
the work week. A transition to a more zonal flow with
modest/gradual height rises should bring a warming trend heading
into next weekend. Low chances for precip also come back into play
as return flow on backside of surface ridge will begin northward
push of frontal boundary.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 745 PM EDT Sat Jun 20 2020

Primarily VFR through the period. Minor shortwaves approaching
late this evening from east central Illinois northeast into
northwest Indiana supporting some shower/isolated thunderstorms
west of KSBN. Given anticipated diurnal nature of activity will
only mention vicinity showers and KSBN. Steep low level lapse
rates will quickly stabilize with loss of heating. A more
substantive shortwave over northwest Arkansas/Missouri Ozarks will
shift east-northeast through the Ohio Valley by Sunday afternoon.
While primary focus with this feature will remain south of
terminals, still ample afternoon MLCAPE to 1500 j/kg and erasure
of surface based convective inhibition will likely lead to
isolated to scattered thunderstorms across northern Indiana,
sufficient chances for a TEMPO inclusion at this time.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SYNOPSIS...Murphy
SHORT TERM...JAL
LONG TERM...JAL
AVIATION...Murphy


Visit us at www.weather.gov/iwx

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




Area Forecast Discussion...Updated Aviation

National Weather Service Saint Louis MO

 1044 PM CDT Sat Jun 20 2020

.UPDATE...
Issued at 919 PM CDT Sat Jun 20 2020

Showers and thunderstorms activity has mostly diminished from
earlier today. There remains some showers over southeast Missouri
that will continue into the overnight hours ahead of a vort max
seen on the water vapor imagery currently over northern Arkansas.
The RAP shows this vort moving slowly northeast into the western
Ohio Valley overnight so will continue with scattered showers and
thunderstorms to the south and east of the St. Louis metro area.
Rest of going forecast still looks good and made little changes to
it.

Britt

&&

.SHORT TERM...  (Through Late Sunday Afternoon)
Issued at 252 PM CDT Sat Jun 20 2020

An upper level trough over the eastern Plains will move east into
the Mississippi Valley by 12Z Sunday morning.  This wave is helping
to ignite convection across central and eastern Missouri this
afternoon.  The weak and diffuse front stalled over western Missouri
is helping to provide a focus for thunderstorm development as well.
SPC mesoanalysis shows 1500-2000 J/Kg MLCAPE and up to around 25 kts
of effective bulk shear.  This is good enough for organized clusters
of storms.  600-700 Joules of DCAPE are also available for downdraft
production, but mid level lapse rates are not that impressive, so
wind continues to be the primary threat with this
afternoon/evening`s storms. Can`t rule out a few hail reports with
the strongest storms though. Most of the convection should weaken
and dissipate this evening with the loss of daytime heating, but
some storms may linger overnight across parts of the eastern
Ozarks and southwest Missouri.

Original thinking for the past couple of days was that the
combination of this afternoon`s/evening`s convection and the upper
level trof would be push the front to the southeast down across
southern Missouri or northern Arkansas.  The latest short range
guidance basically just washes the front out overnight tonight as
southerly flow increases ahead of the next upstream short wave. This
will mean it should be warmer and more humid than originally
forecast.  have bumped up temperatures a bit to around 90 for most
locations, and afternoon dew point forecast into the mid and upper
60s.  The warm and humid air could produce a few afternoon
thunderstorms, however short range guidance is showing some weak low
level short wave ridging moving through the Mid Mississippi Valley
which looks like it will suppress convection.

Carney

.LONG TERM...  (Sunday Night through Next Saturday)
Issued at 252 PM CDT Sat Jun 20 2020

The upper level low currently over south central Canada is forecast
to deepen and drift southeast into the northern Great Lakes Region
by midweek.  This gradually amplifies the upper level flow and and
will turn the flow to the northwest.  Monday should continue to be
warm and humid ahead of the cold front which will be driven south by
the aforementioned amplified flow, and a short wave rippling through
the base of the upper trough will likely set off another round of
convection.  Timing and coverage is uncertain at this point, but it
does look like there will be some fairly widespread rain.  The cold
front should move through on Monday night and cooler/drier air will
move into the Mid Mississippi Valley.  Temperatures will dip to near
or just a few degrees below normal in the low to mid 80s.  Northwest
flow aloft reigns through Thursday when the next upper level ridge
begins building into the Mississippi Valley from the west, and
temperatures rise again into the mid and upper 80s.

Carney

&&

.AVIATION...  (For the 06z TAFs through 06z Sunday Night)
Issued at 1035 PM CDT Sat Jun 20 2020

Light showers will continue around the St. Louis area terminals
and points south and east through 10Z with mainly VFR conditions.
Otherwise dry and VFR conditions are expected through the
remainder of the TAF period. Winds are expected to remain light.

SPECIFICS FOR KSTL:

Light showers will continue around the terminal through 10Z with
mainly VFR conditions. Then dry and VFR conditions are expected
through 06Z on Sunday night before there will be additional
chances for showers and thunderstorms. Winds are expected to
remain light.

Britt

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX



Area Forecast Discussion

National Weather Service Twin Cities/Chanhassen MN

 1104 PM CDT Sat Jun 20 2020

.UPDATE...
Issued at 846 PM CDT Sat Jun 20 2020

Main change to the forecast for the rest of tonight was to start
increasing mention of the dense fog threat in west central WI.
For example, EAU received 0.25" of rain through the afternoon,
with the temperature as we near sunset just 64 degrees. Clearing
skies are working across our WI counties now and with sunset
occurring shortly, we expect areas out toward Eau Claire,
Ladysmith, and Rice Lake to quickly cool past their cross-over
temperatures, with fog becoming locally dense in spots overnight.

As for thunderstorms coming out of the Dakotas, they are running
out of the reservoir of MUCAPE and will continue their weakening
trend as they move into our western CWA. The RAP shows the MUCAPE
tongue that has fed these storms weakening considerably as it
moves east, so like the going forecast, with it looking unlikely
any activity makes it as far east as St. Cloud and Redwood Falls
this evening.

&&

.SHORT TERM...(This evening through Sunday night)
Issued at 254 PM CDT Sat Jun 20 2020

Widespread showers across western Wisconsin will continue eastward
late this afternoon. Meanwhile, a band of thunderstorms across
eastern North Dakota will also head eastward through the
evening. They may become more numerous south into South Dakota
late this afternoon, and then may pose a threat to western MN
this evening. They should be on a weakening trend after sunset
with the loss of instability and it`s likely they will completely
dissipate before reaching St. Cloud and Redwood Falls. Aside from
the possibility for a few rogue showers or storms overnight, it
should be dry for the vast majority until at least late Sunday
morning.

Increasing theta-e throughout the day with a cold front slowly
sagging southeast across the CWA will spark thunderstorm
development during the afternoon. Lapse rates continue to look
poor, so CAPE shouldn`t be too impressive. Up to 2000 J/kg are
possible across far southern MN where rich low level moisture
coincide with slightly better mid level lapse rates. SPC has
upgraded this area to a slight risk. 0-6 km bulk shear of 30-40
kts could allow a few supercells to develop where the best pockets
of instability develop. Otherwise, CAMs favor short line segments
along the cold front, capable mostly of wind damage. The severe
threat will diminish Sunday evening, but shower and thunderstorm
chances will continue into Monday as the front continues to limp
through.

.LONG TERM...(Monday through Saturday)
Issued at 254 PM CDT Sat Jun 20 2020

The best chances for storms Monday will be across southern MN into
western WI. The front will clear the area Monday evening. A large
trough will spin multiple weak disturbances across the region
Tuesday and Wednesday. Coupled with modest daytime heating,
isolated to scattered showers and thunderstorms are likely to
develop each afternoon. This trough will clear to the east late
week, but several waves continuing eastward across the northern
CONUS will keep chances for storms in our future into next
weekend. Temperatures will warm back into the 80s as heights rise
following the departure of the deeper trough from midweek.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1104 PM CDT Sat Jun 20 2020

Four concerns remain this period. 1) how far convection that came
in from the Dakotas makes it into MN this evening, 2) potential
for dense fog at EAU, 3) threat for light showers as early as
Sunday morning, and 4) threat for another round of thunderstorms
late Sunday afternoon. So we`ll tackle all of those briefly.

1) Not much change in thought with these storms outrunning their
instability and weakening to not much more than showers over
western MN. One cell just snuck north of AXN and still do not
expect activity to reach even STC/RWF


2) Confidence has increased that EAU will see dense fog tonight.
Just a question of how long it takes to form, but current TAF may
be to slow to get it going.

3) Shortwave energy will be moving across central/southern MN
Sunday morning. This looks to result in mainly mid level clouds
and trend with models has been to produce less activity with this
energy, so continued to keep things dry through the morning.

4) For the late afternoon TS threat, kept similar timing to what
00z TAFs had. Still a good deal of spread in the models with
where/when storms develop, so stuck with prob30s for now. Front
will be diffuse, but greatest threat for TS by 00z should be from
south central MN up toward the Twin Cities given expected frontal
placement.

KMSP...Greatest TS threat still looks to be in the 22z to 04z
window. Some threat for MVFR cigs exists for after 6z Monday, but
will wait a bit longer before including those in the TAF for
Monday morning.

/OUTLOOK FOR KMSP/
Mon...VFR. Chc aftn SHRA/TSRA. Wind NW 10 kts.
Tue...VFR. Chc aftn SHRA/TSRA. Wind NW 10 kts.
Wed...VFR. Chc aftn SHRA/TSRA. Wind WNW 10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&

$$

UPDATE...MPG
SHORT TERM...Borghoff
LONG TERM...Borghoff
AVIATION...MPG




Updated for aviation forecast discussion.



 &&

.SHORT TERM...(Tonight through Monday night)
Issued at 336 PM CDT Sat Jun 20 2020

Isolated afternoon showers and thunderstorms continue to develop
along decent southwest to northwest CAPE gradient within a 0-2 km
moisture convergence zone along the western limb of the narrow and
departing ridge axis. Given the sharp low level lapse rates,
parcel mixing of dry air aloft and downward momentum, a few of
the thunderstorms may produce wind gusts in excess of 40 knots
this afternoon before coming outflow dominated. The Storm
Prediction Center, in their 3 pm CDT update, added a small part of
southeast MO/southwest IL in a Marginal Risk for severe
thunderstorms to account for isolated strong wind gusts and hail
potential.

With the loss of daytime heating, coverage should diminish
slightly over southeast MO, southwest IL, and west KY. However,
with the continued eastward progression of the western Arkansas
low/MCV toward the WFO PAH forecast area this evening and
overnight, may see an uptick in convective activity in the
aforementioned area around midnight. The high resolution CAM
guidance has been having trouble resolving the recent convection.
Utilized a blend of the Canadian, GFS, and RAP guidance for short
term convective trend tonight through Sunday night.

An ageostrophic response and development of a weak LLJ and
increased instability aloft with the low/trough axis/MCV moving
over the WFO PAH forecast area overnight should increase the
coverage of shower and thunderstorm activity over the eastern part
of the area after 3 am CDT. Stabilization and loss of larger scale
lift should inhibit the redevelopment of widespread convection
behind the trough during the afternoon and evening hours on
Sunday. This trend is a little faster than what has been
advertised the last few days with most of the emphasis on
thunderstorms in the afternoon and evening hours.

The next shortwave rotates around the primary synoptic scale low
in south central Canada late Sunday night. Increased rain chances
again during the morning hours on Monday, gradually decreasing
coverage during the evening over the southern half of the WFO PAH
forecast area. Kept near categorical PoPs near the stalled out
frontal boundary over the northwest 1/3 of the area (southern IL
and southeast MO) where lift is maximized.

Given the higher precipitable water and more efficient rainfall
rates, may need to monitor for isolated overland flooding issues
on Monday. The WFC QPF branch has the WFO PAH forecast area in a
marginal coverage for excessive rainfall.

.LONG TERM...(Tuesday through Saturday)
Issued at 336 PM CDT Sat Jun 20 2020

The long term forecast begins with ongoing showers and storms
throughout the Quad State region. A cold frontal passage just NW of
the CWA will slowly advance through the Quad State Tuesday through
the evening. Precipitation chances will be highest during the day,
then trend downwards overnight. Lingering precip on Wednesday is
most likely in the Kentucky Pennyrile region. Behind the front cloud
cover will diminish and dew points will drop on the order of 10
degrees. Mostly sunny and less humid conditions continue into
Thursday. The GFS produces a weak shortwave that could bring a
showers/storms to the area Thursday afternoon, though with little
agreement from other models, precip chances are kept as a slight
chance.

Low pressure between the Great Lakes and Hudson Bay will start
shifting eastward Thursday night allowing for a more zonal upper-
level flow. High pressure settles into the southeast behind the
stalled out cold front that had crossed the Quad State Tuesday. This
will bring a more southerly surface flow from the Gulf to the Quad
State for the end of the week. Models disagree on development
towards the end of the forecast period. The GFS is more focused on
developing shortwave energy in the Plains moving towards the Great
Lakes while the ECMWF produces more Gulf Coast precipitation that
could be drawn northward. In some manner, a boundary is likely to
form during the weekend connecting these features, but with limited
certainty on relative strength, NBM slight chance to chance PoPs are
held onto for the end of the forecast period.

With widespread rain coverage ahead of the front on Tuesday, highs
are likely to be limited to the lower 80s. Post-frontal, Tuesday and
Wednesday nights will be in the low to mid 60s. For the end of the
week temperatures and humidity will start to climb again, to the
upper 80s for highs and upper 60s for lows.

&&

.AVIATION...
Issued at 625 PM CDT Sat Jun 20 2020

Monitoring scattered thunderstorm activity that could impact
SEMO/SIL/W. KY terminals early this evening. After that, there
could be a bit of a lull before more widespread activity is
expected overnight tonight and into the day on Sunday. MVFR
ceiling and visibility are forecast during that time, as another
round of showers and isolated storms moves through the area from
west to east. While the activity will likely exit southeast MO by
12Z, it will take until later in the day for the activity to exit
KOWB.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&

$$