SPC MD 105

MD 0105 CONCERNING HEAVY SNOW FOR EAST NE…SOUTHWEST INTO CENTRAL IA…NORTHERN MO

MD 0105 Image


Mesoscale Discussion 0105
NWS Storm Prediction Center Norman OK
0726 PM CST Sat Feb 16 2019

Areas affected...East NE...southwest into Central IA...northern MO

Concerning...Heavy snow 

Valid 170126Z - 170630Z

SUMMARY...Heavy snow expected over the next several hours. Up to 1
inch/hr snowfall rates will be possible in some spots.

DISCUSSION...A mid-level shortwave trough and associated 850 mb low
are currently established in the Central Plains, preceded by
deep-layer moisture advection and low-level WAA across the
Mid-Missouri Valley. At the moment, the thermodynamic profile of the
troposphere across the discussion area can be characterized by
near-saturated to saturated conditions in the sfc-700 mb layer (per
00Z TOP observed soundings and recent RAP point-forecast soundings),
with relatively strong WAA advection present in the 925-700 mb
layer, amidst below-freezing temperatures throughout the column. 

The -12 to -17C layer, favorable for dendritic growth, is nearly
saturated and quite deep across the discussion area (per latest
mesoscale analysis) and is expected to remain so for several more
hours, as the aforementioned WAA and large scale ascent continues to
impinge on the region. As such, conditions support at least
occasionally heavy snow throughout the evening hours, with a few
spots potentially seeing accumulation rates of up to 1 inch/hr, as
supported by the latest high resolution model guidance.

..Squitieri.. 02/17/2019

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

ATTN...WFO...LSX...DVN...DMX...EAX...FSD...OAX...TOP...GID...

LAT...LON   41379175 40209199 39589309 39359470 39789599 40169718
            40619810 41599783 42209666 42349506 42249410 41759268
            41379175 

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SPC MD 79

MD 0079 CONCERNING WINTER MIXED PRECIPITATION FOR PORTIONS OF NORTHERN OKLAHOMA…SOUTHERN/EASTERN KANSAS…AND WESTERN MISSOURI

MD 0079 Image


Mesoscale Discussion 0079
NWS Storm Prediction Center Norman OK
0751 PM CST Wed Feb 06 2019

Areas affected...Portions of northern Oklahoma...southern/eastern
Kansas...and western Missouri

Concerning...Winter mixed precipitation 

Valid 070151Z - 070745Z

SUMMARY...Winter mixed precipitation will develop across portions of
northern Oklahoma, southern/eastern Kansas, and western Missouri
tonight. Heavy freezing rain/sleet are possible.

DISCUSSION...A strong upper-level trough is moving onto the Plains
this evening and a strengthening low-level jet is increasing
warm-air advection above a cold air mass across Kansas/Oklahoma. A
couple of elevated multi-cellular convective clusters are moving
along the northern edge of the low-level jet/warm-air advection.
Mid-level lapse rates are steepening as cold air aloft spreads
eastward, which will increase coverage of storms/showers in the next
couple of hours across portions of northern Oklahoma,
southern/eastern Kansas, and western Missouri. The warm-nose should
remain in place tonight within the MCD area at 850-700 mb with below
freezing surface temperatures resulting in freezing rain and sleet.
MUCAPE of 250-1000 J/kg and mixed-phase clouds should result in CG
lightning and could produce locally heavy freezing rain/sleet.
Generally, precipitation rates will be 0.05-0.15" per hour with
widespread ice accumulation expected. In areas with stronger surface
winds, ice accretion will be more efficient and sleet accumulation
is also possible within convective bands/showers.

..Nauslar/Edwards.. 02/07/2019

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

ATTN...WFO...SGF...EAX...TSA...OAX...TOP...ICT...OUN...DDC...

LAT...LON   36889576 36729640 36559698 36309778 36239828 36179871
            36259904 36469929 36779937 37079938 37289936 37759901
            38729772 39409672 39959585 40029518 39979472 39739418
            39399362 39059332 38739318 38399326 38039369 37979382
            37619430 37329469 37129505 37029535 36889576 

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SPC MD 65

MD 0065 CONCERNING HEAVY SNOW FOR SIERRA MOUNTAINS

MD 0065 Image


Mesoscale Discussion 0065
NWS Storm Prediction Center Norman OK
0318 PM CST Sun Feb 03 2019

Areas affected...Sierra Mountains

Concerning...Heavy snow 

Valid 032118Z - 040315Z

SUMMARY...Heavy snow, with rates of 1 inch per hour and locally
exceeding 3 inches per hour at times -- especially at higher
elevations, will develop into the evening.

DISCUSSION...Strong, moist flow into a cooling troposphere is
supporting efficient snow production across much of the Sierra
Mountains. This large-scale pattern is expected to remain in place
through the evening as strong deep-layer ascent increases in
response to the next cyclone moving southward along the California
coast. Increasing ascent is already evident on water-vapor and
infrared satellite imagery, as well as in radar imagery, across the
Sacramento Valley as cloud tops have cooled and banded/cellular
echos have developed. As the lower troposphere cools, snow levels
fall, and these cellular features move into the Sierras, snowfall
rates briefly approaching 3 inches per hour may occur at elevations
as low as 6000-7000 feet. Strong winds will accompany this heavy
snow resulting in blizzard conditions at times.

Although snow will continue well into the overnight snowfall rates
may relax a bit overnight before picking up in intensity again
tomorrow ahead of the next short-wave trough embedded within the
larger-scale trough.

..Marsh.. 02/03/2019

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

ATTN...WFO...REV...HNX...STO...

LAT...LON   37431950 38332036 39532113 39712048 38901987 37781883
            37431950 

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SPC MD 61

MD 0061 CONCERNING HEAVY SNOW FOR EASTERN PENNSYLVANIA INTO SOUTHEASTERN NEW YORK…NEW JERSEY AND ADJACENT PORTIONS OF THE NORTHERN MID ATLANTIC AND SOUTHERN NEW ENGLAND

MD 0061 Image


Mesoscale Discussion 0061
NWS Storm Prediction Center Norman OK
1010 AM CST Wed Jan 30 2019

Areas affected...Eastern Pennsylvania into southeastern New
York...New Jersey and adjacent portions of the northern Mid Atlantic
and southern New England

Concerning...Heavy snow 

Valid 301610Z - 302015Z

SUMMARY...A brief burst of heavy snow, strong wind gusts and reduced
visibilities may accompany the passage of a cold front this
afternoon, perhaps affecting much of the Greater New York City
metropolitan area during the 2-4 PM EST time frame.

DISCUSSION...The leading edge of stronger lower tropospheric cooling
(centered around 850 mb...where temps falling from roughly -15 to
-30C), now surging east of the Allegheny Mountains, is forecast to
continue eastward into western New England and the northern Mid
Atlantic region through 20-22Z.  Model forecast soundings suggest
that is being accompanied by increasing boundary layer
destabilization supportive of deepening convective development, with
tops likely to approach 10,000+ feet, particularly across parts of
eastern Pennsylvania and central/northern New Jersey into
southeastern New York late this afternoon.

Frontogenetic forcing appears to be supporting a narrow, but
sustained, evolving band of convection.  This is likely being aided
by lift within the exit region of a 110-130 kt cyclonic 500 mb jet
streak forecast to nose across the northern Mid Atlantic, lower
Hudson Valley, and southern New England by late this afternoon.

Given the cold thermodynamic profiles, including a layer supportive
of large dendritic ice crystal growth, guidance is suggestive that
the convection may be accompanied by a burst of heavy snow rates
around or in excess of 1 inch per hour.  It appears this may last
only 15 to 30 minutes at any one location, but it may be accompanied
by fairly strong surface wind gusts in excess of 30 kts, and sharply
reduced visibilities.

..Kerr.. 01/30/2019

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

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

LAT...LON   40187685 41577615 42637568 43557345 42817280 42297262
            41427249 40227382 39647578 39647711 40187685 

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SPC MD 43

MD 0043 CONCERNING FREEZING RAIN FOR NORTHEAST KS…NORTHWESTERN MO…SOUTHERN IA

MD 0043 Image


Mesoscale Discussion 0043
NWS Storm Prediction Center Norman OK
0120 PM CST Tue Jan 22 2019

Areas affected...northeast KS...northwestern MO...southern IA

Concerning...Freezing rain 

Valid 221920Z - 222245Z

SUMMARY...Freezing rain rates approaching 0.05 inch per hour are
possible beginning early this afternoon and spreading from west to
east from northeast KS into southeast IA.

DISCUSSION...Surface analysis places a cold front from east-central
KS northeast through the Kansas City metro.  Temperatures are
falling into the upper 20s to near 30 degrees F behind the front.  A
mid-level trough located over the central High Plains this afternoon
will continue to pivot east towards the region and large-scale
forcing for ascent will gradually increase in the vicinity of the
frontal zone this afternoon.  Forecast soundings show a warm nose
with temperatures above freezing around 800 mb atop a 1 km deep
layer at or below freezing---indicative of freezing rain as the
favored precipitation type before transitioning to sleet over KS and
MO later this afternoon.  The latest ECMWF guidance suggests
freezing rain rates near 0.05 inch per 3 hours will become
increasingly common by late afternoon.

..Smith.. 01/22/2019

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

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

LAT...LON   38699674 39939603 40939393 41349229 41059149 40619149
            40459228 40339368 39959472 39139568 38609612 38699674 

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SPC MD 22

MD 0022 CONCERNING HEAVY SNOW FOR NORTHEAST KS…NORTHERN MO…SOUTHERN/EASTERN IA…WESTERN IL

MD 0022 Image


Mesoscale Discussion 0022
NWS Storm Prediction Center Norman OK
0554 PM CST Fri Jan 18 2019

Areas affected...Northeast KS...Northern MO...Southern/Eastern
IA...Western IL

Concerning...Heavy snow 

Valid 182354Z - 190600Z

SUMMARY...Moderate to locally heavy snow rates are possible this
evening.

DISCUSSION...Snow rates have recently intensified across portions of
central/southern IA, in response to increasing deep-layer ascent in
advance of shortwave trough (with multiple embedded vorticity
maxima) moving into the southern Plains. Heavy snow will continue to
be possible across northern MO, central/eastern IA and eventually
into western IL, as low/midlevel frontogenesis (which has been
maximized further north during the day) becomes refocused for a time
this evening across the region. Rates at or above 1 inch/hr will be
possible for at least a few hours at any one location. 

Further to the southwest, the rain/snow line is expected to shift
southeast with time across portions of northeast KS/northwest MO,
with areas currently seeing heavier precip rates from Topeka into
the Kansas City metro area eventually changing over to snow. While
liquid-to-snow ratios will likely be lower compared to areas further
north, locally heavy snowfall rates will be possible for at least a
brief period this evening before the precipitation ends from west to
east later tonight.

..Dean.. 01/18/2019

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

ATTN...WFO...ILX...LSX...DVN...ARX...DMX...EAX...TOP...

LAT...LON   40029522 41759389 42659215 42589114 42479060 42028969
            41169010 40139136 39449343 39059450 38489630 39129685
            40029522 

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SPC MD 17

MD 0017 CONCERNING HEAVY SNOW FOR EASTERN KS TO WEST-CENTRAL IL

MD 0017 Image


Mesoscale Discussion 0017
NWS Storm Prediction Center Norman OK
1134 PM CST Fri Jan 11 2019

Areas affected...Eastern KS to West-Central IL

Concerning...Heavy snow 

Valid 120534Z - 120930Z

SUMMARY...Heavy snow will focus along a corridor from eastern KS,
across central MO, into west-central IL. Snow rates will be on the
order of 1"+ per hour.

DISCUSSION...Well-defined mid-level circulation has evolved over the
central Plains along the KS/OK border near Medicine Lodge (KP28).
Large-scale forcing for ascent appears to be increasing ahead of
this feature and precipitation is responding accordingly. Over the
last few hours the corresponding baroclinic leaf is sharpening which
supports radar trends of an expanding/intensifying shield of heavy
snow across portions of eastern KS into central MO. It appears a
corridor of heavy snow (1"+/hr) will establish itself over the next
few hours from near EMP in KS, downstream just south of the KC
metro, into west-central IL just north of the St. Louis area. Heavy
snow will likely continue along this corridor into the post-dawn
hours.

..Darrow.. 01/12/2019

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

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

LAT...LON   38519602 39339349 39859055 38969025 38119244 37979556
            38519602 

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SPC MD 8

MD 0008 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR FAR SOUTHEAST AL…CENTRAL FL PANHANDLE

MD 0008 Image


Mesoscale Discussion 0008
NWS Storm Prediction Center Norman OK
0505 AM CST Fri Jan 04 2019

Areas affected...Far Southeast AL...Central FL Panhandle

Concerning...Severe potential...Watch unlikely 

Valid 041105Z - 041330Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated damaging wind gusts and perhaps a brief tornado
are possible as the convective line continues eastward into
southeast GA and the central FL Peninsula.

DISCUSSION...Shallow convective line continues to push eastward
across far southeast AL and the western/central FL Panhandle.
Despite a general increase in updraft strength and echo tops, the
line has remained devoid of any lightning onshore. Air mass ahead of
the line has modified slightly, with dewpoints now in the 70s across
the central FL Panhandle and mid 60s dewpoints as far north as ABY
in far southwest GA. This has lead to a modest increase in
instability with MLCAPE now estimated near 500 J/kg. Instability
quickly drops off near the FL Big Bend where warm temperatures aloft
remain in place and cooler low-level trajectories exist.

Surface winds have backed ahead of the line and recent TLH VAD data
suggests 0-1 km SRH over 250 m2/s2 and 0-1 km shear near 30 kt. This
favorable low-level shear coupled with sufficient instability
supports the potential for mesovortices embedded in the convective
line, particularly where deeper, more persistent updrafts exist. As
such, isolated damaging wind gusts and perhaps a brief tornado are
possible. Marginal nature of the threat and low probability of
occurrence will preclude the need for a watch.

..Mosier/Edwards.. 01/04/2019

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

ATTN...WFO...TAE...

LAT...LON   31718511 31808465 31588423 30938394 30128408 29818467
            29688539 29948557 31008502 31718511 

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SPC MD 1664

MD 1664 CONCERNING BLIZZARD FOR NORTHERN IL AND ADJACENT PORTIONS OF EASTERN IA/SOUTHERN WI

MD 1664 Image


Mesoscale Discussion 1664
NWS Storm Prediction Center Norman OK
0654 PM CST Sun Nov 25 2018

Areas affected...Northern IL and adjacent portions of Eastern
IA/Southern WI

Concerning...Blizzard 

Valid 260054Z - 260700Z

SUMMARY...Heavy snow will spread into a larger portion of northern
IL this evening. As stronger winds move in from the west, blizzard
conditions will expand later tonight across the region.

DISCUSSION...00Z surface analysis depicts a 993 mb surface cyclone
just northeast of St. Louis. To the north and northwest of the low,
heavy snow is ongoing from northeast MO into northwest IL, with
stronger winds in the northwestern quadrant of the cyclone producing
blizzard conditions. Dual pol products from KILX/KLOT and recent
surface obs and mPing reports indicate that the rain/snow line is
moving eastward across northern IL, and this trend is expected to
continue as backing surface winds result in increasing low-level
cold advection to the north and northwest of the east-northeastward
moving surface low. Snow should continue spreading into most of the
Chicagoland area between now and 02Z, though areas in the immediate
vicinity of Lake Michigan may see a longer period of mixed
precipitation as northeasterly winds off of the lake maintain a
slightly warmer near-surface layer. 

Substantial convection has been noted near the surface low moving
into southern IL, with a convective character to the precip (and
some thundersnow reports) also noted within cooling cloud tops
across northern IL. Strong low/midlevel frontogenesis will continue
to favor moderate-to-heavy snow to the north of the midlevel low,
with some convective enhancement possible just north of the midlevel
dry slot, where relatively steep lapse rates (in excess of 7 C/km as
noted on ILX/DVN 00Z soundings) will be maintained. Snow rates of
1-3 inches per hour are expected within the primary snow band, which
should shift gradually eastward into northeast IL by late tonight. 

Strong winds (gusts in excess of 40 kt) are resulting in ongoing
blizzard conditions from northeast MO into northwest IL. These
stronger winds will expand eastward with time tonight in conjunction
with the movement of the surface low, resulting in an expansion of
blizzard conditions into northeast IL and perhaps far southeast WI
after 03Z tonight.

..Dean.. 11/26/2018

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

ATTN...WFO...LOT...ILX...MKX...DVN...

LAT...LON   41349111 42049035 42668896 42768779 42008763 41628760
            40978822 40948870 41228944 41369046 41349111 

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SPC MD 1659

MD 1659 CONCERNING BLIZZARD FOR CENTRAL/EASTERN KANSAS…NORTHWEST MISSOURI…FAR SOUTHEAST NEBRASKA…SOUTHWEST IOWA

MD 1659 Image


Mesoscale Discussion 1659
NWS Storm Prediction Center Norman OK
1059 AM CST Sun Nov 25 2018

Areas affected...Central/eastern Kansas...northwest Missouri...far
southeast Nebraska...southwest Iowa

Concerning...Blizzard 

Valid 251659Z - 252200Z

SUMMARY...1-2 inch/hr snowfall rates expected to continue for
several more hours across the area, with occasional blizzard
conditions likely northwest of the surface low.

DISCUSSION...A 998 mb surface low, currently located across
southwest Missouri, is expected to continue moving northeast in
tandem with a pronounced upper-level shortwave trough. The
upper-level trough will continue to deepen throughout the afternoon,
with 500-300 mb relative wind maxima expected to traverse the base
of the trough this afternoon. As a result, large scale ascent is
expected to increase across the area, where strong 925-700 mb WAA
and moisture advection ahead and to the north of the surface low are
currently underway. 

Increasing divergence aloft associated with the approaching
aforementioned upper-level wind maxima will encourage further
deepening of the surface low, with increases in surface wind speeds
likely. Blizzard conditions have already been reported across
several portions of central/northeast Kansas into far southeast
Nebraska, and these conditions are expected to continue across much
of the outlined area as the low continues eastward. Areas roughly
from Washington to Kingman County Kansas westward may continue to
experience near white-out conditions for a few more hours, but the
threat is expected to clear as snow moves out of the area. 

Otherwise, 1-2 inch/hr snowfall rates should pivot eastward across
far northeast Kansas into northwest Missouri and southwest Iowa,
along the axis of a moisture conveyer belt, where low-level warm
air/moisture advection should continue to saturate the
dentritic-growth layer.

..Squitieri.. 11/25/2018

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

ATTN...WFO...LSX...DVN...DMX...EAX...OAX...TOP...ICT...GID...
DDC...

LAT...LON   37389637 37379819 37539933 39149858 40259698 40729631
            41119438 41399290 41009233 40309223 39119280 38099510
            37389637 

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