RSS Mesoscale Discussions from Storm Prediction Center
WW 396 SEVERE TSTM CT MA NH NY PA RI VT CW 271845Z - 280200Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 396
NWS Storm Prediction Center Norman OK
245 PM EDT Tue Jul 27 2021
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Northern Connecticut
Massachusetts
Southern New Hampshire
Eastern New York
Northeast Pennsylvania
Northern Rhode Island
Southern Vermont
Coastal Waters
* Effective this Tuesday afternoon and evening from 245 PM until
1000 PM EDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph possible
SUMMARY...Fast-moving thunderstorms over central New York will track
eastward across the watch area this afternoon and evening. Damaging
winds will be possible with the strongest storms.
The severe thunderstorm watch area is approximately along and 55
statute miles north and south of a line from 45 miles north
northwest of Monticello NY to 10 miles southeast of Boston MA. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU6).
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 395...
AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few
cumulonimbi with maximum tops to 500. Mean storm motion vector
29035.
...Hart
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WW 395 SEVERE TSTM NY PA LE LO 271510Z - 272200Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 395
NWS Storm Prediction Center Norman OK
1110 AM EDT Tue Jul 27 2021
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Western and Central New York
Northeast Pennsylvania
Lake Erie
Lake Ontario
* Effective this Tuesday morning and evening from 1110 AM until
600 PM EDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph possible
Isolated large hail events to 1.5 inches in diameter possible
SUMMARY...A fast-moving line of thunderstorms over Ontario will
track eastward into western New York and intensify through the early
afternoon. Damaging winds will be possible along the leading edge
of these storms.
The severe thunderstorm watch area is approximately along and 65
statute miles north and south of a line from 25 miles west of
Buffalo NY to 40 miles south southeast of Utica NY. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU5).
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
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
28040.
...Hart
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WW 0396 Status Updates
STATUS FOR WATCH 0396 HAS NOT BEEN ISSUED YET
Read more
WW 0395 Status Updates
STATUS REPORT ON WW 395
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 W BUF TO
20 SSW SYR TO 35 N UCA.
FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1365
..MOSIER..07/27/21
ATTN...WFO...BUF...BGM...
STATUS REPORT FOR WS 395
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
NYC003-007-009-013-015-017-023-025-029-051-053-065-069-077-097-
099-101-107-109-121-123-271940-
NY
. NEW YORK COUNTIES INCLUDED ARE
ALLEGANY BROOME CATTARAUGUS
CHAUTAUQUA CHEMUNG CHENANGO
CORTLAND DELAWARE ERIE
LIVINGSTON MADISON ONEIDA
ONTARIO OTSEGO SCHUYLER
SENECA STEUBEN TIOGA
TOMPKINS WYOMING YATES
PAC015-115-271940-
PA
. PENNSYLVANIA COUNTIES INCLUDED ARE
BRADFORD SUSQUEHANNA
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MD 1365 CONCERNING SEVERE THUNDERSTORM WATCH 395... FOR WESTERN/CENTRAL/EASTERN NY...SOUTHERN VT...WESTERN/CENTRAL MA...NORTHERN CT
Mesoscale Discussion 1365
NWS Storm Prediction Center Norman OK
0101 PM CDT Tue Jul 27 2021
Areas affected...Western/Central/Eastern NY...Southern
VT...Western/Central MA...Northern CT
Concerning...Severe Thunderstorm Watch 395...
Valid 271801Z - 271930Z
The severe weather threat for Severe Thunderstorm Watch 395
continues.
SUMMARY...Threat for damaging wind gusts continues across western
and central NY. A downstream watch across eastern NY and adjacent
areas will likely be needed soon.
DISCUSSION...Radar and visible satellite imagery show two lines of
convection pushing across western and central NY. The lead line
extends from RME southwestward to ITH. The second line extends from
FZY southwestward to OLE. While initially stronger, the lead line
has been on a weakening trend for the past half hour. In contract,
the second has seen a gradual increase in intensity. This increase
in intensity appears to be associated with a modest increase in
instability and decrease in convective inhibition ahead of the line.
Additionally, new development has recently occurred over Cattaraugus
and Allegany Counties as the second line intersects the outflow of
the leading convective line. Deep westerly flow aloft will result in
fast storm motion as well as the potential for damaging wind gusts
as these storms continue eastward.
Current estimated storm motion is about 45 kt with the north end of
the line. As a result, it is expected to reach the edge of Severe
Thunderstorm Watch 395 around or before 19Z. Given the recent
trends, a downstream watch will likely be needed across more of
eastern NY and adjacent southern VT, western/central MA, and
northern CT.
..Mosier.. 07/27/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BOX...ALY...BGM...BUF...CTP...
LAT...LON 43247776 43567687 43567597 43427488 42897280 41707313
41767567 41857726 42167875 43247776
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SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1108 AM CDT Tue Jul 27 2021
Valid 271630Z - 281200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
OVER PARTS OF NEW YORK AND NEW ENGLAND...AND THIS EVENING OVER PARTS
OF MINNESOTA...WISCONSIN...AND IOWA....
...SUMMARY...
Severe thunderstorms are possible today from western New York across
parts of New England, and mainly tonight over portions of the upper
Mississippi Valley region.
...NY into New England...
A long-lived MCV that affected MN last evening is now over southeast
Ontario. A line of thunderstorms associated with the MCV is moving
into western NY at over 45 knots. The air mass ahead of the
activity is warming rapidly, with dewpoints in the low/mid 60s
leading to afternoon MLCAPE values of 1000-1500 J/kg. This will
result in intensification of the storms this afternoon over NY with
an increasing risk of damaging winds. Storms are likely persist
into central New England later this afternoon and evening before
weakening.
There is also some potential for re-development of storms over
western NY and northern PA later today, but confidence of this
scenario is lower.
...MN/WI/IA...
A surface baroclinic zone is forecast to strengthen this afternoon
over MN/WI, with hot/humid conditions over southern MN and northerly
winds developing over northern WI. Increasing convergence along the
boundary will lead to at least isolated thunderstorm development
late this afternoon or evening. Sufficient deep-layer shear will
promote supercell storm structures capable of large hail. Storms
may congeal during the evening with an increasing risk of damaging
wind gusts over southern WI.
..Hart/Wendt.. 07/27/2021
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1228 PM CDT Tue Jul 27 2021
Valid 281200Z - 291200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EAST-CENTRAL
MINNESOTA INTO CENTRAL AND SOUTHERN WISCONSIN...
...SUMMARY...
Thunderstorms associated with severe wind gusts, large hail to very
large hail, and a couple tornadoes will be possible Wednesday
afternoon into Wednesday night across parts of the Upper Midwest and
extending into the southern Great Lakes region.
...Upper Midwest into the southern Great Lakes...
A cluster or two of showers/thunderstorms may be ongoing Wednesday
morning from northern MN southward into perhaps the IA/WI border
vicinity within a warm advection regime. This activity will likely
dissipate by the late morning. A subtle mid-level disturbance,
cresting the mid-level ridge centered over the central Great Plains,
will move eastward into western MN by late afternoon. A warm
frontal zone will become draped from the southwest Great Lakes
northwestward through WI into northern MN. Strong heating and a
very moist boundary layer will lead to a very unstable airmass
developing by mid afternoon over the Upper Midwest (2500-4000 J/kg
MLCAPE, locally higher). Suite of convection-allowing models show
an initial cluster of supercells will probably develop during the
late afternoon into the early evening. Large to very large hail,
severe gusts, and a couple of tornadoes are possible. Enlarged
hodographs near the warm front will favor strong mesocyclones but it
is unclear how much of a tornado risk will ultimately develop due to
storm-scale interactions. Nonetheless, an initial cluster of storms
will likely grow upscale into a forward-propagating severe MCS over
the western Great Lakes during the evening with localized intense
gusts (75+ mph) possible with HP supercell to QLCS transitions or
with the more pronounced bowing segments. It seems plausible this
MCS will move across southern Lake Michigan into the southern Great
Lakes during the overnight. The coverage/intensity of gusts will
probably lessen with time as the squall line encounters weaker
buoyancy during the pre-dawn hours.
...Central Appalachians/Mid-Atlantic...
An upper-level trough is forecast to move southeastward across the
Northeast on Wednesday. A moist airmass will likely be in place
across parts of the central Appalachians, where moderate instability
is forecast to develop by afternoon. Although large-scale forcing
will be weak, isolated storms are possible. In addition to the
instability, deep-layer shear will be strong enough to contribute to
a marginal severe threat. A few marginally severe gusts will be
possible in the mid to late afternoon as low-level lapse rates
steepen.
..Smith.. 07/27/2021
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SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1142 AM CDT Tue Jul 27 2021
Valid 271700Z - 281200Z
Elevated highlights were added to portions of eastern Wyoming into
western South Dakota and far northwest Nebraska for this afternoon.
The latest METAR observations already show RH dipping below 25%
across parts of eastern Wyoming. With continued unimpeded diurnal
heating (clear skies depicted by recent visible satellite imagery),
boundary layer mixing should promote widespread 15 mph sustained
south-southeasterly winds through the afternoon. RH is expected to
further dip into the 15-20% range by early afternoon, coinciding
with the stronger winds, as suggested by the latest guidance
consensus. Locally Elevated conditions may also occur across far
northern Montana, along the U.S./Canadian border later today.
Otherwise, isolated dry thunderstorm highlights remain in place
across portions of the Pacific Northwest into the northern Great
Basin/Northern Rockies regions. Relatively high-based thunderstorms
are in progress across portions of central and eastern Oregon,
embedded within a broader region of showers and widespread clouds.
As such, lift from diurnal heating and overall buoyancy will likely
remain limited across portions of northern California, Oregon, and
far northwest Nevada through the day. However, clearer skies/greater
diurnal heating is expected to foster additional storm development
later this afternoon/evening across portions of the Northern
Rockies. Though storms are expected to be generally wetter,
critically dry fuels may compensate to support efficient
lightning-induced fire starts to warrant the maintenance of isolated
dry thunderstorm highlights.
..Squitieri.. 07/27/2021
.PREV DISCUSSION... /ISSUED 0157 AM CDT Tue Jul 27 2021/
...Synopsis...
An upper-level ridge will slowly drift eastward toward the central
Plains today. Thunderstorm activity has been prolific near the
monsoon moisture on the southwest fringe of this upper-level ridge.
Some of this monsoon moisture is advecting northward into the
Pacific Northwest with PWAT values of 1.31 inches on the 00Z MFR
sounding, which is near the daily maximum recorded value for this
RAOB site. Cloud cover limited instability across Oregon on Monday
and kept afternoon thunderstorm activity to a minimum. Expansive
cloud cover is forecast once again on Tuesday across northern
California and eastern Oregon, which could limit convective
coverage. However, with this cloud cover will also come increasing
low-level moisture and therefore, there may not be much heating
required for thunderstorm activity from northern California into
Oregon, especially with a weak shortwave forecast to cross the
region during the afternoon hours.
Farther northeast, less mid-level cloud cover is forecast and thus
surface heating is expected to be sufficient for some afternoon
thunderstorm activity.
Fuels are very dry across the entire Northwest with ERC percentiles
above the 95th percentile and some areas near record fuel dryness.
Therefore, even though some storms may be on the wetter side given
the PWAT values, lighting ignitions are still possible given the dry
fuels.
...Please see www.spc.noaa.gov/fire for graphic product...
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