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SPC Severe Thunderstorm Watch 611

WW 611 SEVERE TSTM CO WY 212045Z - 220300Z
      
WW 0611 Image

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 611
NWS Storm Prediction Center Norman OK
245 PM MDT Wed Aug 21 2019

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Eastern Colorado
  Southeast Wyoming

* Effective this Wednesday afternoon and evening from 245 PM
  until 900 PM MDT.

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

SUMMARY...Isolated severe storms, in the form of sustained
multicells and a few transient supercells, are expected to develop
along the foothills/I-25 corridor of eastern Colorado into southeast
Wyoming. Isolated large hail will be the primary risk as storms
drift east-southeastward through late afternoon/evening, although
localized severe-caliber winds could also occur, particularly across
east-central Colorado.

The severe thunderstorm watch area is approximately along and 45
statute miles east and west of a line from 75 miles north northeast
of Laramie WY to 30 miles southeast of Pueblo CO. 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.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 609...WW 610...

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 450. Mean storm motion vector
32020.

...Guyer

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SPC Severe Thunderstorm Watch 610

WW 610 SEVERE TSTM DC DE MD NJ PA VA CW 211925Z - 220200Z
      
WW 0610 Image

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 610
NWS Storm Prediction Center Norman OK
325 PM EDT Wed Aug 21 2019

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  District Of Columbia
  Delaware
  Eastern Maryland
  New Jersey
  Eastern Pennsylvania
  Northern Virginia
  Coastal Waters

* Effective this Wednesday afternoon and evening from 325 PM
  until 1000 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...Thunderstorms will continue to develop and intensify,
initially along and west of the I-95 corridor this afternoon. The
strongest of these storms will be capable of damaging winds and
possibly severe hail as they spread east-northeastward through early
evening.

The severe thunderstorm watch area is approximately along and 75
statute miles east and west of a line from 35 miles northeast of
Allentown PA to 25 miles southeast of Washington DC. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU0).

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 609...

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
25020.

...Guyer

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SPC Severe Thunderstorm Watch 609

WW 609 SEVERE TSTM CT MA ME NH NJ NY RI VT CW 211750Z - 220100Z
      
WW 0609 Image
0-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 609
NWS Storm Prediction Center Norman OK
150 PM EDT Wed Aug 21 2019

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Connecticut
  Massachusetts
  Far southern Maine
  Southern New Hampshire
  Northern New Jersey
  Southeast New York
  Rhode Island
  Southern Vermont
  Coastal Waters

* Effective this Wednesday afternoon and evening from 150 PM
  until 900 PM EDT.

* Primary threats include...
  Scattered damaging wind gusts to 70 mph possible
  Isolated large hail events to 1.5 inches in diameter possible
  A tornado or two possible

SUMMARY...Storms will continue to develop and intensify particularly
across far eastern New York and southern New England, near and south
of a warm front that will continue to spread slowly northward. Some
supercells with a hail/tornado risk aside from damaging winds are
most probable across southern New England, with damaging winds
otherwise expected with the strongest storms.

The severe thunderstorm watch area is approximately along and 85
statute miles north and south of a line from 30 miles west northwest
of Poughkeepsie NY to 40 miles east of Boston MA. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU9).

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
24025.

...Guyer

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SPC Severe Thunderstorm Watch 611 Status Reports

WW 0611 Status Updates
      
WW 0611 Status Image

STATUS REPORT ON WW 611

THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.

FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1830

..EDWARDS..08/21/19

ATTN...WFO...BOU...PUB...CYS...


STATUS REPORT FOR WS 611 

SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS 

COC001-005-013-014-025-031-035-039-041-059-069-089-101-119-123-
212340-

CO 
.    COLORADO COUNTIES INCLUDED ARE

ADAMS                ARAPAHOE            BOULDER             
BROOMFIELD           CROWLEY             DENVER              
DOUGLAS              ELBERT              EL PASO             
JEFFERSON            LARIMER             OTERO               
PUEBLO               TELLER              WELD                


WYC001-015-021-031-212340-

WY 
.    WYOMING COUNTIES INCLUDED ARE

ALBANY               GOSHEN              LARAMIE             
PLATTE               


THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY.  PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
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SPC Severe Thunderstorm Watch 610 Status Reports

WW 0610 Status Updates
      
WW 0610 Status Image

STATUS REPORT ON WW 610

SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 SSW DCA
TO 15 WSW BWI TO 30 NE BWI TO 15 SSW TTN TO 5 E EWR.

..NAUSLAR..08/21/19

ATTN...WFO...LWX...PHI...CTP...


STATUS REPORT FOR WS 610 

SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS 

DEC001-003-005-212340-

DE 
.    DELAWARE COUNTIES INCLUDED ARE

KENT                 NEW CASTLE          SUSSEX              


MDC003-009-011-017-029-033-035-041-212340-

MD 
.    MARYLAND COUNTIES INCLUDED ARE

ANNE ARUNDEL         CALVERT             CAROLINE            
CHARLES              KENT                PRINCE GEORGES      
QUEEN ANNE'S         TALBOT              


NJC001-005-007-009-011-015-025-029-033-212340-

NJ 
.    NEW JERSEY COUNTIES INCLUDED ARE

ATLANTIC             BURLINGTON          CAMDEN              
CAPE MAY             CUMBERLAND          GLOUCESTER          
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SPC Severe Thunderstorm Watch 609 Status Reports

WW 0609 Status Updates
      
WW 0609 Status Image
340-

STATUS REPORT ON WW 609

SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 NNE NEL
TO 5 W EWR TO 25 NNW EWR TO 30 SSE MSV TO 20 NE MSV TO 35 N POU
TO 10 WNW PSF TO 30 W EEN TO 25 WSW LCI.

FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1829

..NAUSLAR..08/21/19

ATTN...WFO...OKX...BOX...ALY...GYX...


STATUS REPORT FOR WS 609 

SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS 

CTC001-003-005-007-009-011-013-015-212340-

CT 
.    CONNECTICUT COUNTIES INCLUDED ARE

FAIRFIELD            HARTFORD            LITCHFIELD          
MIDDLESEX            NEW HAVEN           NEW LONDON          
TOLLAND              WINDHAM             


MEC031-212340-

ME 
.    MAINE COUNTIES INCLUDED ARE

YORK                 


MAC001-003-005-007-009-011-013-015-017-019-021-023-025-027-
212340-

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SPC MD 1830

MD 1830 CONCERNING SEVERE THUNDERSTORM WATCH 611... FOR CENTRAL COLORADO THROUGH SOUTHEAST WYOMING
MD 1830 Image


Mesoscale Discussion 1830
NWS Storm Prediction Center Norman OK
0539 PM CDT Wed Aug 21 2019

Areas affected...central Colorado through southeast Wyoming

Concerning...Severe Thunderstorm Watch 611...

Valid 212239Z - 220015Z

The severe weather threat for Severe Thunderstorm Watch 611
continues.

SUMMARY...A few instances of hail and locally strong wind gusts
remain possible from central CO through southeast WY through 00Z,
but overall threat is expected to become increasingly marginal with
onset of nocturnal cooling.

DISCUSSION...Isolated storms continue over the higher terrain, but
coverage has remained sparse across most of CO into southeast WY.
With upper ridging aloft, the primary forcing mechanism has been
heating and upslope component over the higher terrain. While the
downstream atmosphere is moderately unstable with 2000 J/kg MLCAPE,
westerly winds aloft remain modest with generally 15-20 kt in the
700-400 mb layer. Limited storm coverage with low confidence that
storms will be able to consolidate, along with weak flow aloft and
increasing convective inhibition, all lower confidence that activity
will be able to move off the higher terrain. Nevertheless, what
storms that do develop will remain capable of producing a few
instances of hail and locally strong wind gusts next couple hours.

..Dial.. 08/21/2019

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

ATTN...WFO...PUB...BOU...CYS...

LAT...LON   42140512 40220442 38200424 38080505 40140558 42080591
            42140512 

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SPC MD 1829

MD 1829 CONCERNING SEVERE THUNDERSTORM WATCH 609... FOR PORTIONS OF NEW ENGLAND
        
MD 1829 Image

Mesoscale Discussion 1829
NWS Storm Prediction Center Norman OK
0520 PM CDT Wed Aug 21 2019

Areas affected...portions of New England

Concerning...Severe Thunderstorm Watch 609...

Valid 212220Z - 220015Z

The severe weather threat for Severe Thunderstorm Watch 609
continues.

SUMMARY...The severe threat continues across much of WW609 with
severe wind as the primary threat. Large hail and a brief, weak
tornado or two are possible as well.

DISCUSSION...Storms continue to move and develop eastward across New
England ahead of an upper-level shortwave trough. A mixed storm mode
is evident with a broken line of storms stretching from southwest
Maine to south of Albany along a surface pressure trough and
discrete cells developing within the warm sector ahead of the line.
MLCAPE 1000-1500 J/kg and 30-40 knots of effective bulk shear will
support some weaker supercells and a few of those have been observed
across New England in the last hour. 

While damaging wind is the main severe threat, marginally large hail
and a brief, weak tornado are possible with any of the stronger,
especially discrete, cells. Areas with more of a easterly component
in the surface wind will increase hodograph curvature/low-level SRH
and be the favored location for these stronger storms. The severe
threat will diminish from west to east as storms moves eastward into
the evening.

..Nauslar/Grams.. 08/21/2019

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

ATTN...WFO...GYX...BOX...OKX...ALY...PHI...BGM...

LAT...LON   40567452 41907438 42657348 43327210 43687143 43747075
            43517023 42937018 42177022 41647024 41367036 41167058
            41047099 40607338 40467409 40567452 

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SPC MD 1828

MD 1828 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR CENTRAL NORTH CAROLINA
        
MD 1828 Image

Mesoscale Discussion 1828
NWS Storm Prediction Center Norman OK
0516 PM CDT Wed Aug 21 2019

Areas affected...central North Carolina

Concerning...Severe potential...Watch unlikely 

Valid 212216Z - 220015Z

Probability of Watch Issuance...5 percent

SUMMARY...Storms may produce a few instances of strong but mostly
sub-severe wind gusts as they move through central North Carolina
next couple of hours.

DISCUSSION...Storms that developed over the mountains of western NC
earlier this afternoon have consolidated into a squall line as they
approach central NC. The downstream atmosphere is weakly capped and
moderately unstable with temperatures around 90F supporting 2000
J/kg MCLAPE. Multicell storms are expected to continue through
central NC next couple hours and might eventually interact with the
seabreeze which could support brief intensification, before
subsequently diminishing as they continue into eastern NC. Isolated
strong wind gusts should remain the primary threat next couple
hours.

..Dial/Grams.. 08/21/2019

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

ATTN...WFO...RAH...GSP...

LAT...LON   36227910 36327853 36047764 35507810 35017902 34887982
            35168043 35787962 36227910 

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SPC Aug 21, 2019 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
0257 PM CDT Wed Aug 21 2019

Valid 212000Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE NORTHEAST AND MID ATLANTIC REGION...AS WELL AS OVER PARTS OF THE
COLORADO FRONT RANGE...

...SUMMARY...
Severe thunderstorms will continue this afternoon and evening across
parts of the Northeast/Mid-Atlantic States, while a few severe
storms will be possible across the central high Plains.

...Discussion...
The overall outlook remains on track, with respect to prior forecast
reasoning.  The main changes in this update will be to extend the
eastern U.S. SLGT risk a bit farther south across parts of the mid
Atlantic region, while removing northern portions of the risk in
parts of New England, and to include a small SLGT risk over the
Colorado Front Range.

In the East, clouds remain dense, and the airmass stable, over
northern portions of Vermont and New Hampshire, with the primary
severe risk likely to remain south of these areas.  Meanwhile, with
recently issued WW #610 extending southward to the Chesapeake Bay
region, SLGT risk is correspondingly being expanded slightly
southward.

In Colorado, shear remains modest -- particularly with southward
extent.  However, with moderate destabilization occurring, and thus
risk for locally intense cells within a narrow corridor, potential
for hail/wind with a few of the strongest storms warrants upgrade to
a small SLGT risk in this area.

Otherwise, no major changes to the outlook are required at this
time.

..Goss.. 08/21/2019

.PREV DISCUSSION... /ISSUED 1132 AM CDT Wed Aug 21 2019/

...Northeast/Mid-Atlantic States...
A shortwave trough will continue to progress east-northeastward from
eastern New York toward northern New England, while a warm front
slowly spreads northward across southern New England. With broken
cloud cover lingering in most areas, modest overall destabilization
is expected along/south of the warm front where low-level/deep-layer
shear will be maximized. The environment will support the
possibility of supercells/bowing segments particularly across
southeast New York and southern New England, with severe hail/wind
possible along with some tornado risk. Multicells with damaging
winds are possible farther south within the warm sector. For
additional short-term details, see Mesoscale Discussion 1825.

...Kansas/Missouri/far southeast Nebraska to Missouri/Illinois...
The remnants of overnight convection continue to decay across the
region with cloud cover/outflow influencing an effective boundary
across southern portions of Kansas/Missouri. Surface-based
thunderstorms should develop/intensify later this afternoon
particularly across southern/eastern Kansas into western Missouri
within a moist/unstable environment. Relatively weak tropospheric
winds may limit overall storm organization, but the strongest storms
will pose a damaging wind/severe hail risk.

...Wyoming/Colorado Front Range to central High Plains...
Isolated to widely scattered thunderstorms should develop this
afternoon over the eastern mountains and foothills from northern
Wyoming across central/southern Colorado, offering the potential for
isolated severe hail and gusts. Activity is expected predominantly
in the post-frontal/upslope region where lift is maximized by a
combination of upslope flow and diabatic surface heating of the
higher terrain (minimizing MLCINH). Mid-level flow is forecast to be
modest; however, vertical shear will be stronger than over lower
elevations ahead of the front because of the backed boundary-layer
winds and relatively extended low-level hodographs.  As such, a
mixture of supercellular and multicellular structures are possible.

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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
0146 PM CDT Wed Aug 21 2019

Valid 221200Z - 231200Z

Minor adjustments were made to ongoing elevated lines based on 12Z
high resolution forecast guidance. However, no significant changes
were made. See previous discussion below.

..Bentley.. 08/21/2019

.PREV DISCUSSION... /ISSUED 0143 AM CDT Wed Aug 21 2019/

...Synopsis...
An upper-level shortwave trough will continue to move east-northeast
across the northern Intermountain West tomorrow. An associated
surface cold front will continue to move south and east into the
Great Basin and through much of the northern Rockies and northern
California. With a pre-frontal surface pressure trough running
parallel and ahead of the cold front, the surface pressure gradient
will strengthen across the Intermountain West along and ahead of the
cold front.

Elevated conditions are expected from northern Arizona/southern
Nevada stretching northeastward into central Wyoming along/ahead of
the surface cold front. Southwest-westerly sustained surface winds
of 15-20 mph and RH values of 8-20% are likely to develop during
tomorrow afternoon and evening across this area. High clouds may
drift into northern Arizona, which could limit the southern extent
of the current elevated area.

Elevated conditions are also likely to develop across
central/eastern portions of the Snake River Plain and vicinity
tomorrow afternoon. The cold front will have passed through the
area, but daytime heating should warm temperatures and mix the
boundary layer enough to result in west-southwest winds of 15-25 mph
and RH values of 15-20%.

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

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