WW 393 SEVERE TSTM MN ND SD 262245Z - 270500Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 393...CORRECTED
NWS Storm Prediction Center Norman OK
545 PM CDT Mon Jul 26 2021
CORRECTED FOR HAIL SIZE
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Northern to central Minnesota
Southeast North Dakota
Northeast South Dakota
* Effective this Monday afternoon from 545 PM until Midnight CDT.
* Primary threats include...
Scattered large hail and isolated very large hail events to 4
inches in diameter likely
Scattered damaging winds and isolated significant gusts to 80
mph possible
A tornado or two possible
SUMMARY...Intense supercell over northwest Minnesota may become a
long-track, cyclic giant hail producing storm across north-central
Minnesota. Additional storms are expected along a front in
south-central to southeast North Dakota, with further development
farther east towards central Minnesota through the evening.
The severe thunderstorm watch area is approximately along and 65
statute miles north and south of a line from 60 miles north of
Mobridge SD to 30 miles north northeast of Duluth MN. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU3).
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.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 392...
AVIATION...A few severe thunderstorms with hail surface and aloft to
4 inches. Extreme turbulence and surface wind gusts to 70 knots. A
few cumulonimbi with maximum tops to 600. Mean storm motion vector
32025.
...Grams
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WW 0393 Status Updates
STATUS FOR WATCH 0393 HAS NOT BEEN ISSUED YET
Read more
WW 0392 Status Updates
STATUS REPORT ON WW 392
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 SW SHD TO
35 SSE NHK.
..DEAN..07/26/21
ATTN...WFO...RAH...RNK...LWX...AKQ...
STATUS REPORT FOR WS 392
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
NCC001-033-057-067-081-135-145-151-157-169-262240-
NC
. NORTH CAROLINA COUNTIES INCLUDED ARE
ALAMANCE CASWELL DAVIDSON
FORSYTH GUILFORD ORANGE
PERSON RANDOLPH ROCKINGHAM
STOKES
VAC007-009-011-019-025-029-031-036-037-041-049-053-067-075-081-
083-085-087-089-093-095-097-101-111-117-127-135-141-143-145-147-
149-175-181-183-199-550-570-590-595-620-650-670-680-690-700-710-
730-735-740-760-800-810-830-262240-
VA
. VIRGINIA COUNTIES INCLUDED ARE
AMELIA AMHERST APPOMATTOX
BEDFORD BRUNSWICK BUCKINGHAM
CAMPBELL CHARLES CITY CHARLOTTE
CHESTERFIELD CUMBERLAND DINWIDDIE
FRANKLIN GOOCHLAND GREENSVILLE
HALIFAX HANOVER HENRICO
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No Mesoscale Discussions are in effect as of Tue Jul 27 00:01:09 UTC 2021.
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0255 PM CDT Mon Jul 26 2021
Valid 262000Z - 271200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PORTIONS
OF EAST-CENTRAL MINNESOTA AND NORTHERN WISCONSIN...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
VIRGINIA/NORTH CAROLINA...
...SUMMARY...
Supercells and bowing structures with large hail and damaging winds
are expected this afternoon/evening from eastern North Dakota into
northern Minnesota. Other locally severe storms capable of damaging
winds will affect portions of Virginia and North Carolina.
...Discussion...
Only change this outlook update is to include 5-percent wind
probabilities in central OK into far south-central KS. The 18z
Lamont, OK raob showed a very unstable airmass with an 18 g/kg
lowest 100 mb mean mixing ratio and 3300 J/kg MLCAPE. Despite very
weak flow through the troposphere and indicative of a pulse
thunderstorm mode, the steepened 0-2 km lapse rates and high PW will
favor water-loaded wet microbursts (localized gusts up to 65 mph)
with the most intense cores. This activity will diminish by
early/mid evening.
..Smith.. 07/26/2021
.PREV DISCUSSION... /ISSUED 1148 AM CDT Mon Jul 26 2021/
..Eastern ND/MN/northern WI/Upper MI this afternoon into tonight...
A broad upper ridge is prominent across much of the CONUS today,
with stronger westerly flow stretching from MT to the Great Lakes
region. At the surface, a moist air mass with dewpoints in the mid
60s extends as far north as ND/MN, where strong daytime heating will
yield MLCAPE values of 1500-2500 J/kg. Deep-layer shear profiles
will also be quite strong across this region, with effective shear
values around 40 knots. These parameters will result in a
conditionally favorable environment for supercells and bowing storm
complexes capable of very large hail and damaging winds. The
primary forecast uncertainty involves the timing and placement of
storms later today. 12z CAM guidance shows considerable diversity,
and given the subtle/weak forcing mechanisms, confidence in the 30%
hail area is not particularly high. Nevertheless, a few HREF
members continue to indicate an active convective day over the
SLGT/ENH risk area, so will leave risk areas mostly unchanged.
...VA/NC...
A hot and very humid low-level air mass is present today over
southern VA and northern NC, with dewpoints in the mid 70s. Strong
heating will result in an axis of MLCAPE over 2500 J/kg from western
NC into south-central VA, where scattered afternoon thunderstorms
are expected. Vertical shear is not particularly strong, but may be
sufficient for a few convective clusters to become organized and
pose a risk of damaging winds and hail. Activity will persist into
the early evening and the onset of diurnal cooling.
...Northern New England...
Moderately strong west-northwesterly mid-level flow stretches across
the northeast states today, where mostly clear skies are present.
This will allow for the development of relatively steep low-level
lapse rates. Isolated thunderstorms are expected to form over the
region, and across eastern ON/QB and move across the MRGL risk area.
The strongest cells could produce locally gusty winds.
...NV/UT...
The corridor of enhanced mid-level winds has shifted northward into
NV/UT today. Yesterday's convection over this region may limit high
temperatures somewhat and lessen the damaging wind potential. But
given the mostly clear skies and consistent forecast of an axis of
thunderstorm development later today, will add a MRGL risk for
locally damaging winds.
Read more
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0237 PM CDT Mon Jul 26 2021
Valid 271200Z - 281200Z
The previous forecast remains on track. The latest guidance
continues to show 1+ inch precipitable water values pivoting around
a mid-level anticyclone across the northwest U.S., providing ample
moisture for isolated to scattered thunderstorm development tomorrow
afternoon and evening, from northern California to the northern
Rockies. Isolated dry thunderstorm highlights remain in place for
areas that have the greatest chance of experiencing dry strikes
(particularly on the periphery of storm cores), and where fuels are
critically receptive to fire spread.
Southerly surface flow will become prevalent across the
central/northern High Plains as surface lee troughing takes shape
tomorrow afternoon and evening. The latest guidance consensus
suggests that minimum RH will range from 15-25% across the western
Dakotas into northwest Nebraska by afternoon peak heating. However,
guidance agreement is not as strong in depicting widespread 15+ mph
sustained surface winds coinciding with the aforementioned surface
RH. Fire weather highlights have been withheld for now, though an
Elevated delineation may be needed in future outlooks should
guidance consensus trend windier.
..Squitieri.. 07/26/2021
.PREV DISCUSSION... /ISSUED 0221 AM CDT Mon Jul 26 2021/
...Synopsis...
Moisture will increase across the Northwest and northern Rockies on
Tuesday. A few weak mid-level shortwave troughs are forecast to move
northward from California and across eastern Oregon and Idaho. These
may provide ample lift for isolated to widely scattered
thunderstorms throughout the day. PWAT values are forecast to be as
high as 1.25 inches in some areas which may limit the ignition
threat somewhat. However, fuels are near record dry across most of
this area and thus will be very susceptible to any lightning. In
addition, forecast soundings show LCLs around 4km with a mostly dry
sub-cloud layer which should evaporate some of the falling rainfall
and may lead to gusty and erratic surface winds.
...Please see www.spc.noaa.gov/fire for graphic product...
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