SPC MD 1806

MD 1806 CONCERNING SEVERE THUNDERSTORM WATCH 512… FOR PORTIONS OF LONG ISLAND NEW YORK…CONNECTICUT…MASSACHUSETTS…RHODE ISLAND

MD 1806 Image


Mesoscale Discussion 1806
NWS Storm Prediction Center Norman OK
0837 PM CST Sun Nov 15 2020

Areas affected...Portions of Long Island New
York...Connecticut...Massachusetts...Rhode Island

Concerning...Severe Thunderstorm Watch 512...

Valid 160237Z - 160430Z

The severe weather threat for Severe Thunderstorm Watch 512
continues.

SUMMARY...The severe threat continues across Severe Thunderstorm
Watch 0512. Damaging gusts are expected to accompany a fast-moving
squall line to the Atlantic coastline.

DISCUSSION...A progressive squall line, with 18 dBZ echo tops
occasionally exceeding 25 kft, continues to pose a damaging wind
threat across portions of southern New England. Numerous
damaging/measured severe gusts have been noted farther west across
southeast New York into New Jersey over the past couple of hours.
Strong low-level Warm air advection continues ahead of the squall,
fostering up to 250 J/kg MUCAPE (mainly within the 850-500 mb
layer), as shown by the latest Mesoanalysis and RAP forecast
soundings. Though buoyancy is mediocre, 50+ kt 925-850 mb wind
fields are in place, and any downward momentum transport that occurs
with the more pronounced downdrafts will support damaging gusts. The
squall is expected to maintain intensity while on land, and is
expected to move out into the Atlantic over the next 2-3 hours.

..Squitieri/Thompson.. 11/16/2020

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

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

LAT...LON   40457391 41437333 42277328 42777309 42847214 42867121
            42807071 42487036 41986994 41677008 41337048 40747197
            40457391 

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SPC MD 1804

MD 1804 CONCERNING SEVERE THUNDERSTORM WATCH 511… FOR FAR EASTERN PENNSYLVANIA…EASTERN MARYLAND…DELAWARE…NEW JERSEY

MD 1804 Image


Mesoscale Discussion 1804
NWS Storm Prediction Center Norman OK
0552 PM CST Sun Nov 15 2020

Areas affected...far eastern Pennsylvania...eastern
Maryland...Delaware...New Jersey

Concerning...Severe Thunderstorm Watch 511...

Valid 152352Z - 160145Z

The severe weather threat for Severe Thunderstorm Watch 511
continues.

SUMMARY...The threat for damaging gusts continues across Severe
Thunderstorm Watch 0511. Damaging gusts will be primarily associated
with a line of storms.

DISCUSSION...A low-topped squall line is currently moving across
eastern PA and northeast MD, with a history of at least scattered
wind damage from Cumberland to Lebanon and Lancaster Counties in PA,
down to Frederick County MD. Storm tops barely reach 25 kft, and the
anticipated line is expected to continue in an ambient thermodynamic
environment characterized by surface temperatures exceeding 60F and
very marginal buoyancy (with the latest RAP forecast soundings
showing 100-150 J/kg MUCAPE, mainly within the 850-600 mb layer).
Despite the weak, elevated instability, very strong forcing for
ascent and intense low-level wind fields suggest that any downward
momentum transport would support damaging gusts with the more mature
segments of the squall. The damaging wind threat is expected to
continue until the squall moves offshore, which will likely be
within the next 2.5-3.5 hours.

..Squitieri/Thompson.. 11/15/2020

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

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

LAT...LON   38617500 38537632 38687733 38917813 39707706 40667612
            41397569 41487488 41367427 40987403 40507387 39787390
            39397419 38937458 38617500 

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SPC MD 1761

MD 1761 CONCERNING FREEZING RAIN FOR EASTERN KANSAS AND FAR WESTERN MISSOURI

MD 1761 Image


Mesoscale Discussion 1761
NWS Storm Prediction Center Norman OK
1101 AM CDT Tue Oct 27 2020

Areas affected...Eastern Kansas and far western Missouri

Concerning...Freezing rain 

Valid 271601Z - 271830Z

SUMMARY...Light to moderate freezing rain will be possible through
the late morning hours for east/southeast Kansas and into far
western Missouri.

DISCUSSION...Regional radar trends show a broad region of
precipitation moving from northern OK into southeast KS and western
MO. Surface temperatures across this area are largely in the upper
20s and low 30s. Aloft, morning regional soundings as well as recent
RAP forecast soundings show a 3-5 C warm nose between 800-700 mb
that is fostering a mixture of freezing rain along with some sleet -
as supported by recent surface observations and mPING reports across
the area. Although most forecast guidance shows temperatures
climbing above freezing by early afternoon, the onset of
precipitation prior to this warm up will allow for at least a couple
hours of light to perhaps moderate freezing rain and sleet.
Temperature trends will be monitored through the day for the
expected warm up, which, if delayed, could result in a prolonged
period of freezing rain.

..Moore.. 10/27/2020

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

ATTN...WFO...SGF...EAX...TOP...ICT...

LAT...LON   39139593 39559556 39739487 39449444 38969425 38609428
            38019436 37369467 37039517 37059559 37089607 37349629
            37939615 38489603 39139593 

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SPC MD 1760

MD 1760 CONCERNING FREEZING RAIN FOR NORTHWEST TEXAS…CENTRAL AND WESTERN OKLAHOMA…AND FAR SOUTHERN KANSAS

MD 1760 Image


Mesoscale Discussion 1760
NWS Storm Prediction Center Norman OK
0840 AM CDT Tue Oct 27 2020

Areas affected...Northwest Texas...central and western
Oklahoma...and far southern Kansas

Concerning...Freezing rain 

Valid 271340Z - 271745Z

SUMMARY...Freezing rain and sleet will continue from central
Oklahoma into the eastern Texas Panhandle through the remainder of
the morning.

DISCUSSION...Recent mPING reports from central OK and northwest
Texas indicate that freezing rain with embedded pockets of sleet
continue to overspread the region. The recent 12 UTC Norman, OK
sounding reveals a 7-8 C warm nose between 800-700 mb on top of a ~1
km deep sub-freezing level (with a minimum temperature near -6 C).
This thermodynamic profile supports the observed precipitation
trends, and with little change expected in the next few hours,
should continue to favor freezing rain with embedded sleet. The
strong 850-700 mb isentropic ascent that is the primary forcing of
this morning's precipitation is expected to persist into the early
afternoon hours, especially across central OK per recent guidance.
This will also act to reinforce the warm nose aloft and continue to
support freezing rain. Although models do show a signal for surface
temperatures to warm just above freezing by around 18 UTC for
central OK, there is some uncertainty in the temperature forecast
given widespread cloud cover, persistent northerly winds/weak cold
advection at the surface, and only modest warm advection at around
925 mb. As such, confidence in ice accumulations will remain highest
along and west of the I-44 corridor where precipitation along the
mid-level warm front is most likely to overlap with sub-freezing
surface temperatures through the early afternoon. Due to the early
timing of this winter storm, fall foliage remains on most trees,
which when combined with ice accumulation and 10-15 mph surface
winds will increase the potential for widespread power outages
through the day.

..Moore.. 10/27/2020

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

ATTN...WFO...TSA...ICT...FWD...OUN...DDC...SJT...LUB...AMA...

LAT...LON   35860061 36839954 37339883 37819762 37999674 37679610
            37019568 36269616 35329695 34959710 34199742 33699837
            33339891 33309939 33510018 33840067 34530084 35370079
            35860061 

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SPC MD 1755

MD 1755 CONCERNING WINTER MIXED PRECIPITATION FOR FAR EAST-CENTRAL NM…MUCH OF THE TX PANHANDLE…WESTERN OK/EASTERN OK PANHANDLE

MD 1755 Image


Mesoscale Discussion 1755
NWS Storm Prediction Center Norman OK
0117 AM CDT Mon Oct 26 2020

Areas affected...Far East-Central NM...Much of the TX
Panhandle...Western OK/Eastern OK Panhandle

Concerning...Winter mixed precipitation 

Valid 260617Z - 261015Z

SUMMARY...Mixed winter precipitation, predominantly sleet, is
expected this morning from far east-central NM across the TX
Panhandle into western OK.

DISCUSSION...Regional radar imagery has shown an increase in
precipitation coverage during the past few hours as isentropic
ascent persists across the southern Plains/southern High Plains. 00Z
AMA sounding sampled a shallow cold layer well, revealing a cold
layer extending to 850 mb (about 1 km deep). Above this cold layer,
warm temperatures associated with the persistent southwesterly flow
aloft resulted in a strong inversion, with 700 mb temperatures near
7 to 8 deg C. This results in a thermodynamic profile supporting
mixed precipitation, predominantly sleet, once the mid-level layer
moistens enough to erode the dry layer in place. The increase in
precipitation coverage noted in regional radars is likely evidence
of that ongoing moistening process, which is expected to continue
and will soon support precipitation reaching the surface over much
of this region. 

Given the anticipated persistence of the southwesterly flow aloft
and resulting maintenance of the warm layer aloft, the expectation
is for an area of mixed winter precipitation to develop from far
east-central NM across the TX Panhandle in western OK/eastern OK
Panhandle. Sleet is expected to be the dominant precipitation type.
Additionally, elevated instability, based the at the top of the warm
layer around 700 mb, could contribute to higher precipitation rates
as well as occasional lightning. Current observations show lightning
within the precipitation band from Potter County TX into Harper
County OK.

..Mosier.. 10/26/2020

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

ATTN...WFO...OUN...DDC...LUB...AMA...ABQ...

LAT...LON   35500332 36190236 37200002 36959882 36039911 35399962
            34630075 34150235 34130337 34390375 34850375 35500332 

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SPC MD 1744

MD 1744 CONCERNING SEVERE THUNDERSTORM WATCH 500… FOR SOUTHWEST IOWA…FAR NEBRASKA…FAR NORTHWEST MISSOURI

MD 1744 Image


Mesoscale Discussion 1744
NWS Storm Prediction Center Norman OK
1128 PM CDT Sun Oct 11 2020

Areas affected...Southwest Iowa...Far Nebraska...Far Northwest
Missouri

Concerning...Severe Thunderstorm Watch 500...

Valid 120428Z - 120600Z

The severe weather threat for Severe Thunderstorm Watch 500
continues.

SUMMARY...An isolated wind damage threat is expected to persist
across southwest Iowa and far northwest Missouri for another one to
two hours. Weather watch issuance is unlikely beyond the expiration
of Ww 500.

DISCUSSION...A line of strong to severe thunderstorms is ongoing
across western Iowa extending south-southwestward into far southeast
Nebraska. The RAP has weak instability ahead of the line with MLCAPE
of 500 to 1000 J/kg. This combined with strengthening low-level flow
will support continued thunderstorm development over the next few
hours. The Des Moines WSR-88D VWP currently has 60 kt of 0-6 km
shear which will be enough to continue an isolated severe threat a
little while longer with the stronger cells embedded in the line. A
few damaging wind gusts will be possible along the leading edge of
the line as it moves eastward across southwest Iowa and far
northwest Missouri. However, as instability continues to weaken
during the early overnight period, the severe threat will become
increasingly marginal.

..Broyles.. 10/12/2020

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

ATTN...WFO...DMX...EAX...OAX...TOP...

LAT...LON   42469435 42369485 42059510 41079543 40319581 39979575
            39869556 39819505 40029457 41049423 42059394 42469435 

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SPC MD 1743

MD 1743 CONCERNING SEVERE THUNDERSTORM WATCH 500… FOR EASTERN NEBRASKA AND FAR WESTERN IOWA

MD 1743 Image


Mesoscale Discussion 1743
NWS Storm Prediction Center Norman OK
0902 PM CDT Sun Oct 11 2020

Areas affected...eastern Nebraska and far western Iowa

Concerning...Severe Thunderstorm Watch 500...

Valid 120202Z - 120400Z

The severe weather threat for Severe Thunderstorm Watch 500
continues.

SUMMARY...The potential for severe wind will continue for portions
of central Minnesota as well as eastern Nebraska and far western
Iowa through at least 03 UTC.

DISCUSSION...Recent radar trends from MN show an organized squall
line, which suggests that 40-45 knot effective bulk shear is
compensating for relatively weak (around 500 J/kg MLCAPE)
instability. Convection will likely begin to diminish as it moves
eastward into the cool side of a diffuse surface warm front, but
will continue to pose a severe wind potential in the near term
(through at least 03 UTC) for central MN. With temperatures in the
mid 60s (and dewpoints in the 40s) across eastern MN, a downstream
watch is not anticipated at this time. 

Further south, the cold front has overtaken the main line of storms
per recent surface and radar observations from KOAX. This will
further favor a linear storm mode for the rest of the evening.
Despite increasing inhibition from nocturnal cooling, stronger
ascent associated with the cold front should maintain convection for
the next few hours. Downward trends in MRMS vertically integrated
ice and warming IR cloud top temperatures, combined with a
transition to a linear storm mode, suggest a downward trend in the
hail potential overall, though a few instances of severe hail can
not be ruled out with any stronger updraft pulses. Although severe
wind is possible along the entirety of the line, portions of
southeast NE may see a locally higher wind threat associated with
accelerating convection along the cold frontal surge.

..Moore/Dial.. 10/12/2020

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

ATTN...WFO...MPX...DMX...FSD...OAX...GID...

LAT...LON   40979791 42009666 42409634 42849593 43769563 44629550
            45269523 45759511 45929479 45859429 45329389 44969383
            44489390 43889416 43149459 42549494 41999520 41659539
            41169556 40739560 40459611 40429688 40569759 40979791 

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SPC MD 1719

MD 1719 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR PORTIONS OF EASTERN KANSAS INTO WESTERN MISSOURI

MD 1719 Image


Mesoscale Discussion 1719
NWS Storm Prediction Center Norman OK
1053 AM CDT Sun Sep 27 2020

Areas affected...Portions of Eastern Kansas into Western Missouri

Concerning...Severe potential...Watch unlikely 

Valid 271553Z - 271730Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated strong thunderstorms with the potential for large
hail are possible late this morning and into the afternoon. The
relatively isolated nature of the stronger storm coverage may
preclude a Severe Thunderstorm Watch.

DISCUSSION...A strong thunderstorm has recently developed along/near
a southward-moving cold front across portions of Lyon County,
Kansas, with a 1.25-1.5" hail report recently near Admire. RAP
mesoanalysis suggests 500-1000 J/kg of MLCAPE in this area with
effective bulk shear of 40-50 knots. While there may be a tendency
for the cold front to undercut some updrafts, at least a few
updrafts should persist long enough to produce severe hail,
especially given the strong shear through the hail growth zone.
Thunderstorms should continue to move across eastern Kansas and into
Western Missouri, as depicted by several 12Z HREF members. 

While convective coverage may remain too limited for a watch
issuance, trends will continue to be monitored and a Slight Risk
will be added in this area with the 1630Z Convective Outlook to
cover this threat.

..Elliott/Grams.. 09/27/2020

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

ATTN...WFO...LSX...SGF...EAX...TOP...ICT...

LAT...LON   39189581 39519474 39339345 38819277 38359296 38059373
            37879465 38019558 38539631 39189581 

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SPC MD 1654

MD 1654 CONCERNING SEVERE THUNDERSTORM WATCH 478…479… FOR SOUTHERN MO…FAR SOUTHERN IL AND FAR WESTERN KY

MD 1654 Image


Mesoscale Discussion 1654
NWS Storm Prediction Center Norman OK
1243 PM CDT Mon Aug 31 2020

Areas affected...southern MO...far southern IL and far western KY

Concerning...Severe Thunderstorm Watch 478...479...

Valid 311743Z - 311915Z

The severe weather threat for Severe Thunderstorm Watch 478, 479
continues.

SUMMARY...Strong, locally damaging gusts will continue to be
possible across parts of central into southeast MO through
mid-afternoon.

DISCUSSION...A line of convection is currently tracking southeast at
around 40-45 kt across central MO into southern MO. If this storm
motion continues, convection could approach the edges of WW 478 and
479 in southeast MO around 19z. Recent CAPPI trends have shown some
weakening of cores over the last hour, and IR satellite indicates
modest warming of cloud tops. It is likely that convection has
reached peaked intensity. 0-6km shear is rather weak downstream,
though the airmass remains moderately unstable with MLCAPE values as
high as 2000 J/kg noted in 17z mesoanalysis. Furthermore,
approximately 50 kt of rear inflow has been measured by regional
radar. As a result, some severe potential could develop with
southeastward extent and move outside of the current severe
thunderstorm watches. The need for a downstream watch will be
evaluated.

Further west, convection has struggled to intensify as it develops
south/southeast into southwest MO. This is likely due to some
remaining inhibition from earlier morning convection/outflow.
Portions of WW 478 could be cancelled early if convective trends
continue to weaken across the region.

..Leitman.. 08/31/2020

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

ATTN...WFO...PAH...MEG...LSX...LZK...SGF...

LAT...LON   36479283 36529393 36729430 37079448 37409447 37639427
            37929224 38069129 37999019 37758891 37658869 37368841
            36968834 36598856 36478911 36358977 36529123 36479283 

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SPC MD 1650

MD 1650 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR PARTS OF NORTHEASTERN EAST CENTRAL KANSAS INTO NORTHWEST AND WEST CENTRAL MISSOURI

MD 1650 Image


Mesoscale Discussion 1650
NWS Storm Prediction Center Norman OK
0456 AM CDT Mon Aug 31 2020

Areas affected...Parts of northeastern east  central Kansas into
northwest and west central Missouri

Concerning...Severe potential...Watch possible 

Valid 310956Z - 311200Z

Probability of Watch Issuance...40 percent

SUMMARY...It is not yet certain that a severe weather watch will be
needed, but thunderstorms developing across the region could pose
increasing potential for marginally severe hail and strong surface
gusts through daybreak.

DISCUSSION...Forcing for ascent associated with a modest, veering
(to an increasingly westerly component) pre-frontal low-level jet
appears to be contributing to ongoing increasing convective
development in a corridor across northeastern and east central
Kansas.  Although the Rapid Refresh suggests that this jet may begin
to weaken shortly, lift appears to be increasingly focused within a
weakness in inhibition associated with the warm elevated mixed-layer
air, where the eastward advection of seasonably high moisture
content is contributing to most unstable CAPE of 2000-3000 J/kg.  

Given this destabilization, thunderstorm activity seems likely to
continue to develop and intensify through daybreak.  Although the
region will remain between the belts of stronger westerlies aloft,
veering profiles with height along this corridor may be contributing
to deep-layer shear at least marginally sufficient for organized
strong/severe convection.

Furthermore, as a southeastward advancing cold front begins to
overspread the region by 11-13Z, enhancement of lift, where it
intersects this band of elevated convection, may contribute to an
intensifying, upscale growing cluster of storms.  This could be
accompanied by increasing risk for strong surface gusts, in addition
to occasional marginally severe hail.

..Kerr/Edwards.. 08/31/2020

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

ATTN...WFO...EAX...OAX...TOP...

LAT...LON   40339513 39539380 38649374 38089457 38389541 39519609
            40039625 40339513 

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