RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Thu Jul 2 07:34:01 UTC 2020.
No Mesoscale Discussions are in effect as of Thu Jul 2 07:34:01 UTC 2020.
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1222 AM CDT Thu Jul 02 2020
Valid 021200Z - 031200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR A PORTION OF
THE GREAT PLAINS INTO THE LOWER MISSISSIPPI VALLEY AND IN PARTS OF
NEW ENGLAND...
...SUMMARY...
Clusters of strong to locally severe thunderstorms may develop today
across parts of the Great Plains into lower Mississippi Valley, and
in northern New England. Severe gusts and hail are the hazards.
...Great Plains...
A belt of moderate cyclonic mid-level flow will largely remain
across the northwestern CONUS today with the southeastern fringe of
stronger flow over the western Dakotas. A mid-level ridge axis will
be located farther east over the mid-upper MS Valley. An effective
boundary extending south from the Canadian border will extend into
the central High Plains as a lee trough. In the vicinity of the
boundary, low-level convergence and strong heating will contribute
to a gradual erosion of convective inhibition by mid-late afternoon.
A moist boundary layer featuring mid 50s to 60s F dewpoints will
contribute to moderate instability from the Dakotas into the central
High Plains. Widely spaced strong to severe thunderstorms capable
of large hail/severe gusts are possible from the late afternoon into
the evening.
Farther south across the OK vicinity, a very moist airmass featuring
70s F dewpoints will become strongly unstable by midday. Despite
very little large-scale forcing for ascent, widely scattered
thunderstorms are possible initially near a southeast-northwest
oriented boundary and subsequently near convective outflow. This
activity will probably begin during the afternoon and continue into
the early evening. Severe gusts and large hail are the primary
risks.
...Lower MS Valley...
A very moist boundary layer will become strongly unstable by the
early afternoon from AR into southern MS. Model guidance indicates
a few possible clusters of thunderstorms perhaps developing from
near early-day activity over the Ozarks and in a separate area
farther south in MS. Damaging gusts and marginally severe hail are
possible with the stronger cores. This activity will likely
diminish during the early evening.
...Northern New England...
A belt of moderate northwesterly flow will overspread northern New
England as a mid-level low meanders east into the western Atlantic
away from the Northeast U.S. Strong heating coupled with orographic
ascent, and weak large-scale ascent associated with an impulse
embedded in the flow, will support widely scattered storms by
midday. Additional storms and increasing convective coverage are
expected during the afternoon as storms move south into VT/NH and
the Adirondacks. Gusty winds with localized wind damage and perhaps
marginally severe hail are the threats with these storms.
..Smith/Bentley.. 07/02/2020
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SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0102 AM CDT Thu Jul 02 2020
Valid 031200Z - 041200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN
MONTANA INTO NORTH DAKOTA/NORTHWESTERN SOUTH DAKOTA...
...SUMMARY...
A few severe storms will be possible Friday from the northern
Intermountain region to the northern Plains.
...Synopsis...
Little change overall is expected to the upper pattern over the U.S.
Friday, as the western and eastern U.S. troughs persist, along with
an intervening central U.S. ridge. A belt of moderate anticyclonic
westerly-southwesterly flow will evolve from the northern
Intermountain region and into the Prairie Provinces, and then
southeastward across Ontario and the Great Lakes region. Within
this arcing belt of flow, embedded perturbations will support areas
of enhanced thunderstorm coverage.
At the surface, a generally weak/nondescript pattern is expected
from synoptically, as the prevailing upper ridging persists. More
subtle, sub-synoptic-scale boundaries will prevail through the
period.
...Northern Intermountain region into the north-central states...
Lingering convection may be ongoing at the start of the period over
the eastern Dakotas/mid Missouri Valley region, though any severe
risk will likely have diminished prior to the start of the period.
Meanwhile, a series of small-scale perturbations embedded in the
upper flow are expected to cross the Idaho/Montana/Wyoming vicinity
through the day, and eventually reach the northern Plains. With
ample destabilization expected across the northern High Plains and
Dakotas during the afternoon, and 30 to 40 kt mid-level flow atop
low-level southeasterlies, CAPE/shear combination will be sufficient
to support isolated severe/supercell storms. Farther west across
central Montana/northwestern Wyoming and into southeastern Idaho,
instability should remain marginal, but still supportive of a few
isolated/fast-moving storms, and attendant risk for locally
gusty/damaging winds with a few of the strongest updrafts. Risk
should peak during the afternoon and early evening across Montana,
and my linger through the evening across the Dakotas area before
diminishing overnight.
...The Northeast...
A mid-level vort max is forecast to move southeastward across the
Northeast Friday, within background northwesterly cyclonic flow.
Modest destabilization is expected across the lower Great Lakes
region and toward the Mid Atlantic area, supporting development of
afternoon showers and thunderstorms. With moderate northwesterlies
aloft, storms will move relatively quickly southeastward with time,
along with local/attendant risk for gusty winds capable of tree
damage. Convection should peak during the late afternoon, and then
diminish with the loss of diurnal heating.
..Goss.. 07/02/2020
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SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Thu Jul 02 2020
Valid 041200Z - 051200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN INTERMOUNTAIN REGION/NORTHERN PLAINS...AND SOUTHWARD TO THE
CENTRAL HIGH PLAINS...
...SUMMARY...
Isolated strong/severe storms will be possible Saturday from the
northern Intermountain region east across the north-central U.S.,
and southward to the central High Plains.
...Synopsis...
Persistent northwestern U.S. troughing will remain in place Day
3/Saturday, with a belt of enhanced west-northwesterly flow from the
Pacific Northwest across the northern Intermountain region and into
the north-central U.S. -- cresting the central U.S. upper ridge.
In the east, a belt of stronger cyclonic flow will be confined to
the Northeast and adjacent Canadian Maritimes, while weaker/broadly
cyclonic flow covers a larger portion of the eastern half of the
country.
At the surface, a generally weak/nondescript pattern is expected
synoptically, with smaller-scale, sub-synoptic boundaries
prevailing.
...Montana eastward across the Northern Plains, and central High
Plains...
Showers and thunderstorms may be ongoing across parts of the Dakotas
at the start of the period, which would spread eastward with time
toward Minnesota. Near a possible remnant MCV, storms may
reinvigorate during the afternoon -- possibly accompanied by local
risk for gusty/damaging winds and hail across this region.
Meanwhile, as daytime heating results in airmass destabilization,
afternoon storm development is expected across the Montana vicinity
near the next in a series of upper disturbances moving through the
enhanced belt of anticylonic west-southwesterlies aloft. Storms
will also develop southward across the central High Plains vicinity,
in the presence of a series of weaker upper disturbances progged to
linger across the area, within weaker flow field aloft.
As storms in all areas spread eastward, a few of the stronger storms
will be capable of producing severe weather -- largely in the form
of locally damaging winds and hail. At this time, will introduce
only a 5%/MRGL risk area, due to some areal/temporal uncertainty
with respect to where the greatest storm coverage will exist, and
how the storms may organize at smaller scales. SLGT risk upgrade
for parts of the region may be needed in later outlooks.
..Goss.. 07/02/2020
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SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1137 PM CDT Wed Jul 01 2020
Valid 021200Z - 031200Z
...Synopsis...
Moderate mid-level southwesterly flow will persist across the Great
Basin today. Deep mixing is expected this afternoon with some
stronger winds transporting to the surface. Surface winds are
expected to be 15 to 20 mph. Relative humidity across the region
will be in the 10 to 18 percent range. Some localized critical
conditions are possible in southern Nevada and western Utah, but
these conditions are not expected to be widespread enough to warrant
a Critical area.
Monsoon moisture has started to advect into the Southwest and low
50s dewpoints are expected in southern Arizona by this afternoon.
Some isolated storms (likely dry) will be possible in Colorado
today, but greater storm coverage is expected in southern Arizona
and New Mexico. However, these storms are expected to be mostly wet
as PWATs surge above 1 inch across the region.
..Bentley.. 07/02/2020
...Please see www.spc.noaa.gov/fire for graphic product...
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SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1145 PM CDT Wed Jul 01 2020
Valid 031200Z - 041200Z
...Synopsis...
Moderate mid-level southwesterly flow will remain across the Great
Basin on Friday. Winds are expected to increase to 15 to 20 mph
across southern Nevada and western Utah Friday afternoon as deep
mixing transports some of the stronger mid-level flow to the
surface. In addition, a weak shortwave trough is expected to cross
the Sierra during the day and lead to some enhanced downslope flow
in western Nevada late in the afternoon and during the evening. Wind
speeds could exceed 20 mph with relative humidity of 10 to 15
percent. Duration may be the primary limiting factor for critical
conditions, but a Critical area may be needed in further outlooks.
Some dry thunderstorms are possible from northern Arizona and New
Mexico into Utah and Colorado. Any storms in this region will likely
be dry given PWAT values around 0.5 inches. However, there is some
uncertainty about storm coverage which precludes the inclusion of an
IsoDryT area at this time.
..Bentley.. 07/02/2020
...Please see www.spc.noaa.gov/fire for graphic product...
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