000
WWUS20 KWNS 072017
SEL1
SPC WW 072017
MNZ000-NDZ000-SDZ000-080200-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 471
NWS Storm Prediction Center Norman OK
320 PM CDT Wed Sep 7 2016

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
  West Central Minnesota
  Southeast North Dakota
  Northeast South Dakota

* Effective this Wednesday afternoon and evening from 320 PM
  until 900 PM CDT.

* Primary threats include...
  Scattered large hail and isolated very large hail events to 2
  inches in diameter possible
  Scattered damaging wind gusts to 70 mph possible
  A tornado or two possible

SUMMARY...Thunderstorms developing over central ND/SD will track
eastward across the watch area this afternoon and early evening. A
few of the storms may be capable of large hail and damaging wind
gusts.  An isolated tornado is also possible.

The severe thunderstorm watch area is approximately along and 95
statute miles east and west of a line from 50 miles north of Fargo
ND to 40 miles west southwest of Watertown SD.  For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU1).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

AVIATION...A few severe thunderstorms with hail surface and aloft
to 2 inches.  Extreme turbulence and surface wind gusts to 60
knots. A few cumulonimbi with maximum tops to 500. Mean Storm
motion vector 26035.

...Hart

000
ACUS11 KWNS 091542
SWOMCD
SPC MCD 091542
IAZ000-MOZ000-NEZ000-091715-

Mesoscale Discussion 1665
NWS Storm Prediction Center Norman OK
1042 AM CDT Fri Sep 09 2016

Areas affected...Eastern NE, Western IA

Concerning...Severe potential...Watch possible

Valid 091542Z - 091715Z

Probability of Watch Issuance...60 percent

SUMMARY...Thunderstorms are expected to gradually increase in
areal coverage across eastern NE.  Large hail is possible with
this activity as it spreads/develops into western IA.  A Severe
Thunderstorm Watch is being considered.

DISCUSSION...Thunderstorms have recently developed along frontal
zone from south central into northeastern NE.  This activity is
evolving within a fairly moist environment characterized by steep
mid-level lapse rates and modest deep-layer shear.  While
inhibition was noted on 12z soundings across the central Plains,
frontal convergence appears responsible for what are likely near-
surface based thunderstorms.

Latest MRMS data suggest several cells are producing at least
marginally severe hail and hail will likely be the main threat as
convection continues to evolve over eastern NE.  This activity
should spread into western IA during the early afternoon as the
surface front surges southeastward.

..Darrow/Grams.. 09/09/2016

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...DMX...EAX...FSD...OAX...GID...LBF...

LAT...LON   41139962 41819852 42499564 41809436 40729495 40009850
            41139962

000
ACUS01 KWNS 090602
SWODY1
SPC AC 090600

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Fri Sep 09 2016

Valid 091200Z - 101200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
CENTRAL PLAINS AND MID-MO VALLEY INTO THE OZARK PLATEAU...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
SOUTHERN/CENTRAL PLAINS NORTHEASTWARD ACROSS THE LOWER OH VALLEY
AND MID-MS VALLEY...

...SUMMARY...
Areas of severe storms capable of damaging winds and some large
hail are possible this afternoon and evening from the central
Plains into the mid-MS Valley. More isolated activity is expected
from the TX Panhandle into Ohio and southern Lower Michigan.
 
...SYNOPSIS...
A midlevel shortwave trough initially over the northern Rockies
will amplify across the central/northern Plains. An associated
cold front will surge southeastward as a surface anticyclone
builds over the central Rockies, and will extend from the upper MS
Valley into the southern Plains by early Saturday morning. An
antecedent moist and unstable pre-frontal air mass will support
widespread thunderstorm development along the cold front during
the afternoon and evening. Surface low pressure will deepen across
WI into the Upper Peninsula of MI late in the period, while an
associated warm front retreats northward to near Lake Huron.
Elsewhere, a pair of midlevel anticyclones will meander across the
Southeast and near the Four Corners, while a weak cutoff low
drifts northward along the coast of southern CA.
 
...CENTRAL PLAINS ACROSS THE MID-MO VALLEY INTO WESTERN IA...
Primary focus for thunderstorm initiation across the mid-MO Valley
and central Plains will be along the aforementioned cold front, as
midlevel height falls overspread the  central Plains and mid-MS
Valley in association with an amplifying shortwave trough. This
area is also where confidence is highest in strong
heating/destabilization occurring amidst low-mid 70s dewpoints
within a plume of steepening midlevel lapse rates. A few
supercells could occur with initial development with a primary
threat of large hail and isolated damaging wind gusts from
southern KS into western IA, and possibly a tornado. Convection
should grow upscale into a south/southeastward moving MCS into
OK/MO overnight before weakening late from TX into the mid-MS
Valley.
 
...MO EASTWARD ACROSS SOUTHERN ILLINOIS AND INDIANA...
Early morning thunderstorms are expected to be ongoing across
parts of KS/MO within a weak warm air advection regime, but should
diminish in coverage by late morning. Considerable spatial
uncertainty exists regarding the position of an associated outflow
boundary that is expected to be in place across MO, which may
provide the focus for renewed thunderstorm development during the
afternoon. However, deep-layer wind profiles will be favorable for
a few clusters or supercells to develop near the outflow boundary,
which could pose a threat for isolated strong to damaging winds
and perhaps a tornado across southern/central MO into southern IL,
with hail potential more limited by weak lapse rates aloft. More
rapid return of low-level moisture should occur ahead of the
approaching cold front late in association with a modestly
strengthening low-level jet, and should support convection into
the late evening and overnight across Indiana into southern lower
MI.

..Rogers/Gleason.. 09/09/2016

$$

000
ACUS02 KWNS 090600
SWODY2
SPC AC 090600

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Fri Sep 09 2016

Valid 101200Z - 111200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL KY
TO NORTHEAST OH, FAR NORTHWEST PA, AND FAR SOUTHWEST NY...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING
THE SLIGHT RISK FROM NORTHERN MIDDLE TN THROUGH THE UPPER OH
VALLEY TO NY...

...SUMMARY...
Strong to severe storms will be possible Saturday afternoon from
central KY through OH into northwest PA to far western NY, while a
marginal risk for a few strong to severe storms is forecast across
NY.  Damaging winds will be the primary threat.

...SYNOPSIS...
An amplified, progressive shortwave trough will move through the
Great Lakes and OH Valley region during the first half of
Saturday, and likely reach southern Quebec to NY/PA by 12z Sunday.
An attendant surface low will deepen this forecast period as it
tracks northeast from northern Lake Michigan and into Quebec to
the east of James Bay by the end of the forecast period.  A
trailing cold front should extend through the mid MS Valley and
Ozarks to north TX early Saturday morning, and advance quickly
eastward through the OH/TN Valleys and into the northeast states,
while the western extent moves southward approaching the northwest
Gulf Coast. In the northeast, a warm front will shift north from
PA/NJ through southern/central NY and southern New England through
Saturday afternoon.  Deep-layer wind fields will be strengthening
through the forecast period from west to east attendant to the
progressive midlevel trough

...OH/KY/NORTHWEST PA/WESTERN NY...
Southwesterly low-level flow developing across the OH Valley later
tonight will allow moisture return to be underway across the upper
OH Valley, with a narrow corridor of richer moisture expected in
the pre-frontal warm sector Saturday afternoon.  Although there
exists some potential for early day cloudiness, the degree of
moisture return and some surface heating should allow for MUCAPE
to be 1000 j/kg.  Greatest height falls (40-60-m per 12-hr at 500
mb) will be from KY through OH to northwest PA/western NY by peak
heating.  Storms are expected to develop Saturday afternoon as the
cold front moves through the slight risk area.  Effective bulk
shear of 30-35 kts should allow for organized storms with line
segments producing damaging winds as the primary severe threat.
However, a tornado threat will be possible into northeast OH to
far western NY where low-level hodographs should have the
greatest curvature.

...SOUTHERN AND CENTRAL NY...
The return of a very moist air mass is expected by Saturday
afternoon as the warm front moves north, and the warm sector
spreads into much of southern and central NY with surface dew
points in the upper 60s to around 70F.  Despite weak midlevel
lapse rates, surface heating of the rich moisture should result in
marginal to pockets of moderate instability.  Storm development
will be possible as the warm front advances northward, with
sufficient bulk shear for organized storms.  However, uncertainty
in destabilization suggests this region will remain a marginal
severe-weather threat.  Deep-layer winds will strengthen with the
approach of the Great Lakes/OH Valley trough Saturday night across
NY into western New England.  However, a stabilized boundary layer
should limit the potential for strong winds to reach the surface
with any storms along the cold front.

..Peters.. 09/09/2016

$$ 

000
ACUS03 KWNS 090730
SWODY3
SPC AC 090730

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Fri Sep 09 2016

Valid 111200Z - 121200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
No severe weather is expected across the contiguous U.S. on Sunday
and Sunday Night.

...SYNOPSIS...
A shortwave trough will remain progressive Sunday as it moves
through New England and reaches the Canadian Maritimes region by
12z Monday.  As this occurs, the strongest flow aloft should be
confined to the northern tier states as a positively tilted trough
develops into the northwest states.  Meanwhile, a small midlevel
circulation center may move inland across Central CA.

...NEW ENGLAND...
A cold front attendant to the northeast states shortwave trough is
forecast to move east of much of New England by early Sunday
afternoon.  Although storms will be possible along and ahead of
this portion of the cold front, weak instability should limit the
severe-weather threat Sunday morning.

...SOUTHERN VA/CAROLINAS THROUGH THE GULF COAST STATES...
Thunderstorms will be possible Sunday afternoon and evening from
southern VA and the Carolinas, southwest through the Gulf Coast
states where moderate instability is forecast. However, weak bulk
shear should preclude a severe-weather threat.

...ELSEWHERE...
Thunderstorms will be possible into portions of the Four Corners
states and central Sierra Mountains, though weak instability and
shear will preclude a severe-weather threat.

..Peters.. 09/09/2016

$$  

638
ACUS48 KWNS 090900
SWOD48
SPC AC 090859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Fri Sep 09 2016

Valid 121200Z - 171200Z

...DISCUSSION...
A bifurcation of the day 3 northwest states trough is expected by
the early part of day 4 (Monday).  The westernmost portion of the
trough should evolve into a closed low Monday night, extending
from the northern intermountain west to northern/central CA.
Meanwhile, the other portion of the trough will shift east across
the central Canadian prairie provinces and ND/northern MN toward
Ontario during day 4.  This trough will remain progressive during
day 5 (Tuesday) and day 6(Wednesday), reaching the Great
Lakes/Quebec and the northeast/mid-Atlantic states, respectively.
Medium range models are in agreement through day 5, generally
cutting off the western states closed low from zonal flow located
over western and central Canada.  However, beyond day 5, the ECMWF
and GFS diverge with the evolution of the closed low, as the ECMWF
shifts this system east and the GFS keeps it cutoff in the west.  

MONDAY (DAY 4)...A cold front attendant to the shortwave trough
moving east across central Canada should advance east from MN into
WI and the upper Great Lakes region, while the trailing portion
moves southeast and south toward the mid MS Valley and through the
central Plains.  Although moderate instability may develop across
the warm sector, stronger forcing aloft and deep-layer shear
should remain north of the front.  This will preclude the
inclusion for 15-percent severe-weather probabilities.

TUESDAY (DAY 5)...The cold front will continue east and southeast
through the Great Lakes toward the Northeast states, OH Valley and
Midwest.  Although strong shear will be expected across these
areas, very weak instability should preclude the severe-weather
threat. 

..Peters.. 09/09/2016

$$

000
FNUS21 KWNS 090657
FWDDY1

Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0157 AM CDT Fri Sep 09 2016

Valid 091200Z - 101200Z

...NO CRITICAL AREAS...

...SYNOPSIS...
A shortwave trough over the northern and central Rockies will
shift east over the Plains today, resulting in weakening deep-
layer west-northwesterly flow. In the wake of the trough, a
shortwave ridge will build over the northern Rockies late in the
period. At the surface, high pressure will build over the interior
west, and a very dry airmass will persist across the Great Basin.
Weak surface winds will mitigate fire weather concerns despite
very low relative humidity values from northern CA and southern OR
across much of the Great Basin.

..Leitman.. 09/09/2016

...Please see www.spc.noaa.gov/fire for graphic product...

$$

000
FNUS22 KWNS 090659
FWDDY2

Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0158 AM CDT Fri Sep 09 2016

Valid 101200Z - 111200Z

...SYNOPSIS...
The shortwave ridge over the Rockies will shift eastward over the
Plains and upper Midwest by Sunday morning as another shortwave
trough begins to dig into the Pacific Northwest. At the surface, a
trough will develop from central MT south-southeast into central
CO as high pressure migrates east toward the Plains. This will
lead to a favorable surface pressure gradient for gusty west-
southwest winds across parts of northwest CO into southern WY.

...PORTIONS OF FAR NORTHWEST CO INTO SOUTH-CENTRAL WY...
West/southwest winds will increase by midday as boundary-layer
mixing to around 700 mb occurs. Expect speeds to around 15 mph
with occasionally higher gusts. A dry airmass will be in place
with PW values around 0.15 inches forecast. RH values are expected
to fall into the 10-15 percent range with perhaps some spotty
single-digit values. 

..Leitman.. 09/09/2016

...Please see www.spc.noaa.gov/fire for graphic product...

$$  

000
FNUS28 KWNS 082051
FWDD38

Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0351 PM CDT Thu Sep 08 2016

Valid 101200Z - 161200Z

A mid/upper-level trough will shift eastward to New England and
the Canadian Maritimes this weekend, as another drops southeast
from Western Canada into the Pacific Northwest. Early next week,
ensemble guidance continues to suggest that this trough will
become progressively sheared, with a closed low developing over
the northern Great Basin, and ridging building over northern
portions of the Pacific Northwest. Late next week, stronger zonal
flow aloft may become relegated to portions of Canada and the
northeast CONUS.
 
...D3(SAT)-D4(SUN) -- NORTHERN/CENTRAL ROCKIES...
Enhanced west-northwesterly flow aloft will remain over the region
this weekend, as the aforementioned Pacific Northwest trough
pushes southeast and maintains a relatively tight height gradient.
Gusty westerly surface winds should materialize each day in
response, with the strongest likely on day 4 (Sunday).
Furthermore, dry air will continue to be advected across the
region, favoring minimum RH values around 10-20 percent.
Confidence in breezy/dry conditions has increased enough to
introduce a 40-percent area across southern WY on day 3
(Saturday), and the ongoing one is maintained for day 4 (Sunday). 

...D4(SUN)-D5(MON) -- SOUTHERN CALIFORNIA TO THE GREAT BASIN...
Along the southern/southeastern periphery of the western
trough/closed low, increasing southwesterly flow aloft will
support breezy conditions from the higher terrain/slopes of
interior southern CA northeastward to northwestern CO. Dry air
will be maintained across this region, such that minimum RH values
around 5-15 percent appear probable. While some enhancement of
fire-weather concerns is anticipated, forecast winds do not appear
strong enough at this time to support any probabilistic areas. 

...D4(SUN)-D6(TUE) -- PORTIONS OF THE PACIFIC NORTHWEST...
With surface ridging building southward across interior portions
of the Pacific Northwest and northern Rockies, areas of gusty
north-northeasterly winds are expected late this weekend into
early next week, including offshore flow along coastal ranges in
western OR and northern CA. Fire-weather concerns should increase
accordingly, but uncertainty regarding fuel receptiveness and
forecast wind strength preclude probabilistic areas at this time.
 
..Picca.. 09/08/2016

...Please see www.spc.noaa.gov/fire for graphic product...

$$