SPC Severe Thunderstorm Watch 235

WW 235 SEVERE TSTM NY VT 291855Z - 300100Z
      
WW 0235 Image
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 235
NWS Storm Prediction Center Norman OK
255 PM EDT Fri May 29 2020

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Far northeast New York
  Vermont

* Effective this Friday afternoon and evening from 255 PM until
  900 PM EDT.

* Primary threats include...
  Scattered damaging wind gusts to 65 mph possible
  Isolated large hail events to 1.5 inches in diameter possible
  A tornado or two possible

SUMMARY...A supercell or two embedded within multiple clusters may
progress across the Champlain Valley and parts of Vermont through
mid-evening. Locally damaging winds should be the main hazard.

The severe thunderstorm watch area is approximately along and 55
statute miles east and west of a line from 40 miles northeast of
Burlington VT to 60 miles southwest of Montpelier VT. 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.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 234...

AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 55 knots. A
few cumulonimbi with maximum tops to 450. Mean storm motion vector
22030.

...Grams

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SPC Severe Thunderstorm Watch 234

WW 234 SEVERE TSTM MD NJ NY PA VA WV 291825Z - 300100Z
      
WW 0234 Image
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 234
NWS Storm Prediction Center Norman OK
225 PM EDT Fri May 29 2020

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Central Maryland
  Northwest New Jersey
  Central and eastern New York
  Eastern Pennsylvania
  Far northern Virginia
  Eastern West Virginia Panhandle

* Effective this Friday afternoon and evening from 225 PM until
  900 PM EDT.

* Primary threats include...
  Scattered damaging wind gusts to 65 mph possible
  Isolated large hail events to 1.5 inches in diameter possible
  A tornado or two possible

SUMMARY...Clusters of strong to locally severe storms are expected
to persist through mid-evening. Damaging winds appear to be the
primary threat.

The severe thunderstorm watch area is approximately along and 60
statute miles east and west of a line from 85 miles northeast of
Binghamton NY to 35 miles east southeast of Hagerstown MD. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU4).

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 55 knots. A
few cumulonimbi with maximum tops to 450. Mean storm motion vector
22030.

...Grams

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SPC Severe Thunderstorm Watch 235 Status Reports

WW 0235 Status Updates
      
WW 0235 Status Image
STATUS REPORT ON WW 235

THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.

..JEWELL..05/29/20

ATTN...WFO...BTV...


STATUS REPORT FOR WS 235 

SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS 

NYC019-031-292240-

NY 
.    NEW YORK COUNTIES INCLUDED ARE

CLINTON              ESSEX               


VTC001-005-007-009-011-013-015-017-019-021-023-027-292240-

VT 
.    VERMONT COUNTIES INCLUDED ARE

ADDISON              CALEDONIA           CHITTENDEN          
ESSEX                FRANKLIN            GRAND ISLE          
LAMOILLE             ORANGE              ORLEANS             
RUTLAND              WASHINGTON          WINDSOR             


THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY.  PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.

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SPC Severe Thunderstorm Watch 234 Status Reports

WW 0234 Status Updates
      
WW 0234 Status Image
STATUS REPORT ON WW 234

SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 NNW BWI
TO 35 E CXY TO 45 W ABE TO 40 SE IPT TO 30 N IPT.

..JEWELL..05/29/20

ATTN...WFO...LWX...PHI...ALY...BGM...OKX...CTP...


STATUS REPORT FOR WS 234 

SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS 

MDC015-025-292240-

MD 
.    MARYLAND COUNTIES INCLUDED ARE

CECIL                HARFORD             


NJC019-037-041-292240-

NJ 
.    NEW JERSEY COUNTIES INCLUDED ARE

HUNTERDON            SUSSEX              WARREN              


NYC001-007-017-021-025-027-035-039-041-043-053-057-065-071-077-
083-091-093-095-105-107-111-113-115-292240-

NY 
.    NEW YORK COUNTIES INCLUDED ARE

ALBANY               BROOME              CHENANGO            
COLUMBIA             DELAWARE            DUTCHESS            
FULTON               GREENE              HAMILTON            
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SPC MD 762

MD 0762 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF NORTH CENTRAL PENNSYLVANIA INTO SOUTHERN NEW YORK
MD 0762 Image

Mesoscale Discussion 0762
NWS Storm Prediction Center Norman OK
0354 PM CDT Fri May 29 2020

Areas affected...Parts of north central Pennsylvania into southern
New York

Concerning...Severe potential...Watch unlikely 

Valid 292054Z - 292300Z

Probability of Watch Issuance...20 percent

SUMMARY...A few locally strong wind gusts may continue with
convection overspreading the region through 6-8 PM EDT.  The need
for a severe weather watch is now not anticipated, but trends will
continue to be monitored.

DISCUSSION...Fairly vigorous thunderstorm development is being
maintained along the leading edge of an east-northeastward advancing
convectively generated surface cold pool.  Forward propagation is
around 35 kt, largely parallel to the sheared 40-50 kt southerly
deep-layer ambient mean flow.  With easterly low-level system
relatively inflow emanating from boundary-layer air characterized by
rather weak CAPE on the order of 500 J/kg, substantive further
intensification seems unlikely.  However, strong peak gusts
approaching severe limits could persist with the convective system
another couple of hours.

..Kerr/Grams.. 05/29/2020

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

ATTN...WFO...BGM...BUF...CTP...PBZ...

LAT...LON   40967913 41457893 42097867 42527828 42717765 42377671
            41597704 40977804 40967913 

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SPC May 29, 2020 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook
      
Day 1 Outlook Image
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0258 PM CDT Fri May 29 2020

Valid 292000Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
OHIO VALLEY AND CENTRAL APPALACHIANS INTO THE CHAMPLAIN VALLEY...

...SUMMARY...
Scattered severe thunderstorms primarily capable of producing
damaging winds will continue across parts of the Northeast states
through about 9 PM EDT.

...Discussion...
Few adjustments appear necessary to the ongoing outlook at this
time.  Primary changes at this time are to reduce the hail
probability across the Northeast, where primary severe risk will
remain locally damaging wind gusts into the evening, and to reduce
the MRGL risk area in the west (i.e. removing probabilities from
Oregon and vicinity).

..Goss.. 05/29/2020

.PREV DISCUSSION... /ISSUED 1041 AM CDT Fri May 29 2020/

...Northeast...
Scattered thunderstorms are expected across a broad swath of the
region. These should be primarily focused along a cold front in OH,
pre-frontal convergence zone off the Lower Great Lakes in western
NY, and along a lee trough from eastern NY to northern VA. While
mid-level lapse rates will remain weak, robust boundary-layer
heating is underway, especially ahead of the lee trough. With
strengthening mid-level southwesterlies, 30-50 kt effective shear
will be supportive of a mixed mode of transient supercells embedded
within clusters that should largely congeal into multiple linear
segments. Scattered damaging winds should be the primary threat.
Convection along the lee trough will have the best chance to produce
severe hail given larger buoyancy with MLCAPE likely reaching
1000-2000 J/kg, as well as the possibility of a tornado or two
during the late afternoon and early evening. 

...Northwest...
Isolated thunderstorms should develop at peak heating within an arc
of ambient anticyclonic mid-level flow across the northern Rockies,
most likely off the Sawtooths and Big Horns. Sufficient deep-layer
shear and steep lapse rates will exist for a risk of localized
severe gusts and marginally severe hail into this evening.

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SPC May 29, 2020 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook
      
Day 2 Outlook Image
Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1230 PM CDT Fri May 29 2020

Valid 301200Z - 311200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE PACIFIC NORTHWEST...

...SUMMARY...
Widely scattered severe thunderstorms are expected Saturday
afternoon/evening particularly across the Pacific Northwest, with
isolated severe risk arcing from there southeastward across the
northern and central High Plains.

...Synopsis...
While broad upper troughing shifts slowly eastward across the
eastern half of the U.S., an upper low is forecast to move
north-northeastward across northern California and the Pacific
Northwest on Saturday.  In between, ridging will prevail over the
Intermountain region.

At the surface, a cold front will advance slowly eastward across New
England and the Atlantic Coast states.  In the West, a compact
surface low will shift northward across the Pacific Northwest ahead
of the upper system, while an arcing lee trough persists across the
northern and central High Plains.

...Pacific Northwest...
As ascent increases across Oregon and Washington through the day,
ahead of the upper low, thunderstorms are expected to develop within
a destabilizing environment as diurnal heating of a relatively moist
low-level airmass yields moderate (generally 1000 to 2000 J/kg)
mixed-layer CAPE across parts of central Oregon and into Washington.
 Enhanced southerly flow through a deep layer will yield not only
ample shear for organized/rotating storms, but also fast storm
motions, with upscale growth into northward-moving clusters
expected.  Along with risk for hail, locally damaging winds are
expected, as storms shift northward through the afternoon and
evening hours.

...Western Montana and across the northern/central High Plains...
Showers and scattered thunderstorms are expected to develop in an
arc-shaped zone around the periphery of the upper ridge during the
afternoon as modest diurnal destabilization occurs, with development
aided by easterly/southeasterly low-level upslope flow. 
Moderate/anticyclonic westerly/northwesterly winds aloft will
contribute to ample shear, such that a few storms may reach severe
levels, capable of gusty/damaging winds and hail locally.  Storms
should continue into the evening hours, before diminishing
overnight.

...Coastal Carolinas/southeast Virginia...
Scattered thunderstorms -- and perhaps a storm or two nearing severe
levels -- are expected during the afternoon near/ahead of the
advancing cold front, and near sea-breeze boundaries.  While shear
is expected to be weak, and thus storms largely disorganized, an
isolated gust or two capable of tree damage may occur, before storms
diminish by early evening.

..Goss.. 05/29/2020

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SPC Day 2 Fire Weather Outlook

SPC Day 2 Fire Weather Outlook
          
Day 2 Fire Weather Outlook Image
Day 2 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0255 PM CDT Fri May 29 2020

Valid 301200Z - 311200Z

...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF CENTRAL AND EASTERN
NEVADA INTO FAR WESTERN UTAH AND FAR NORTHWEST ARIZONA...

Much of the previous forecast remains on track, with adjustments
made to the ongoing critical, elevated, and isolated dry
thunderstorm highlights to reflect the latest model guidance. In
addition, locally elevated conditions may occur across portions of
the southern High Plains, with the lack of upper-level support for a
stronger wind field precluding any delineations at this time.
Breezy, occasionally locally dry conditions may also be observed by
afternoon peak heating in northern New England with the passage of a
cold front. Nonetheless, the lack of a more robust favorable wind/RH
overlap, and the possibility of accumulating precipitation across
the region limits confidence in delineating fire weather highlights.
Lastly, scattered thunderstorms with wetting rains are expected
across the Pacific Northwest, and occasional, erratic gusty winds
are possible across the Columbia Basin given a dry sub-cloud layer
extending past 700 mb. Still, fuels do not appear to be dry enough
to support a robust wildfire spread threat, precluding an isolated
dry thunderstorm delineation at this time.

..Squitieri.. 05/29/2020

.PREV DISCUSSION... /ISSUED 0153 AM CDT Fri May 29 2020/

...Synopsis...
An upper-level closed low situated over the California coast will
continue moving onshore while merging with the upper-level ridge
anchored over the West. As this process occurs, the closed low will
transition into an open wave while lifting northeastward into
portions of the Pacific Northwest.

...Portions of the Great Basin...
The core of the mid-level jet streak is forecast to be situated atop
the region by mid afternoon on Saturday, resulting in stronger
sustained surface wind speeds of 20-30 mph, gusting to 40-50 mph.
Meanwhile, RH values should fall into the teens and approach the
single digits in a few spots. Fuels in the region will remain
receptive to large-fire spread, given further drying that will take
place on D1/Friday. Thus, critical fire-weather conditions can be
expected over much of east-central Nevada into far western Utah.
This region is surrounded by potential for elevated fire-weather
conditions, where sustained surface winds are expected to remain in
the 15-20 mph range.

...Four Corners Region...
A continuation of diurnally driven isolated convection is expected
in areas under the influence of the upper-level ridge and where
residual moisture is present. PWAT values are expected to remain
near or below 0.75 inches over the region, supporting the notion of
dry thunderstorm potential and lightning-induced fire ignitions
where fuels are receptive.

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

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