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LU9DCE > ALERT    19.01.19 08:15l 189 Lines 10021 Bytes #7 (0) @ WW
BID : 16859_LU9DCE
Subj: Storm Prediction Center 19 01
Sent: 190119/0700Z 16859@LU9DCE.TOR.BA.ARG.SOAM LinBPQ6.0.17

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Mesoscale Discussion 0023 NWS Storm Prediction Center Norman OK
0658 PM CST Fri Jan 18 2019
Areas affected...Southeast MN...Northeast IA...Southern WI...Far
Northern IL
Concerning...Heavy snow
Valid 190058Z - 190700Z
SUMMARY...Moderate to locally heavy snow rates will be possible
this evening, with a decreasing trend expected from west to east
with time.
DISCUSSION...The persistent heavy snow band across portions of
southern MN and far northeast IA has begun exhibiting a weakening
trend in the last 1-2 hours. The midlevel frontogenesis that
sustained this band across southern MN should continue to weaken
this evening, as a northern stream shortwave trough moving across
the Dakotas continues moving southeastward as it deamplifies.
Meanwhile, low-to-midlevel frontogenesis may become refocused to
some extent further southeast from far northeast IA into southern
WI and northern IL later this evening, in response to the deepening
cyclone moving across the southern Plains. Moderate ascent through
the dendritic growth layer will support relatively efficient snow
production, with moderate to locally heavy snow rates remaining
possible through the evening.
Snowfall should begin spreading into northeast IL (including the
Chicagoland area) after 03Z, while snow rates further west across
northeast IA and southern MN should substantially diminish by
this time.
..Dean.. 01/19/2019
...Please see for graphic product...
LAT...LON   42619090 42859214 43209305 43629368 43899333 44029231
43559020 43018849 42738806 42688788 41848770 41548836 42258995
 SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1158
PM CST Fri Jan 18 2019
Valid 191200Z - 201200Z
...SUMMARY...  Scattered to numerous thunderstorms, some of which
could be severe, are expected across parts of the Gulf Coast states
today and tonight. Damaging wind gusts and isolated tornadoes should
be the main threats.
...Synopsis...  A strong upper trough with attendant 50-80+ kt
mid-level jet rounding its base will overspread the Southeast
today. 45-55 kt south-southwesterly low-level jet will likewise
translate eastward over the surface warm sector across MS/AL/GA
and the western FL Panhandle through this evening. At the surface,
an area of low pressure initially over the Mid-South will develop
eastward across the TN Valley today, eventually reaching the
Mid-Atlantic by the end of the period. A cold front extending
southward from this low will sweep quickly eastward across the
Southeast, with the strong to severe thunderstorm threat mainly
confined along/near the front.
...Southeast...  Numerous thunderstorms will likely be ongoing at the
start of the period along the cold front extending from near Memphis,
TN southward generally along the MS River to southern LA. Although
low-level moisture return will remain limited ahead of the front,
low 60s surface dewpoints combined with modest daytime heating
and gradually cooling mid-level temperatures should support weak
instability across the warm sector for much of central/eastern MS,
AL, western GA, and the western FL Panhandle through the day. A
gradual increase in convective intensity seems probable as the line
of thunderstorms moves eastward into AL by early afternoon, and 40-60
kt of effective bulk shear will easily support updraft organization
within the line. A few embedded supercells cannot be ruled out,
although the linear nature of the cold front suggests a QLCS will
be the dominant storm mode. Isolated strong to damaging winds will
likely be the main threat, but enlarged low-level hodographs owing
to a strongly strengthening/veering wind profile in the 0-3 km layer
will also support a threat for isolated tornadoes.  A slow decrease
in intensity should occur from late evening into the overnight as
this convection eventually outpaces the modest low-level moisture
return while moving across central/eastern GA and the FL Peninsula.
...Eastern NC...  As the upper trough approaches the East Coast,
the surface warm sector will make some attempt to advance
northward across coastal portions of NC early Sunday morning
as the low-level jet strengthens over this region. However,
the potential for surface-based thunderstorms over land appears
too uncertain/conditional to include any severe probabilities at
this time.
..Gleason/Dean.. 01/19/2019
 SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1148
PM CST Fri Jan 18 2019
Valid 201200Z - 211200Z
...SUMMARY...  Isolated thunderstorms are possible early in the
day across the Outer Banks of North Carolina.
...Synopsis and Discussion...  An extensive upper trough will
approach the East Coast early in the day, with a meridional southerly
midlevel jet of 80-100 kt. Low pressure will be situated over
the Delmarva at 12Z Sunday, and will deepen as it moves into the
Canadian Maritimes. A cold front will extend south from the low,
and will be near the Outer Banks of NC early. Any showers and
thunderstorms that are ongoing at 12Z Sunday will quickly move
offshore. Shear profiles will be very strong initially but will
quickly veer in the low-levels, further reducing instability which
will begin the day only marginally favorable for strong wind gusts.
Elsewhere, a potent shortwave trough will move into northern CA late
in the day, with increasing large-scale lift. While precipitation
will occur, forecast soundings show little if any instability to
support thunderstorms. However, an isolated lightning strike cannot
be ruled out Sunday evening.
...MAXIMUM RISK BY HAZARD...  Tornado:  <2%     - None Wind:     <5%
- None Hail:     <5%     - None
..Jewell.. 01/19/2019
 SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 1149
PM CST Fri Jan 18 2019
Valid 211200Z - 221200Z
...SUMMARY...  Thunderstorms are not expected across the country
on Monday.
...Synopsis...  A powerful upper trough will exit the Northeast
during the day with high pressure across much of the East. Meanwhile,
another upper trough will move from the Great Basin across the Four
Corners states, emerging into the High Plains Tuesday morning. A
surface low will develop into the central Plains, and south
winds will increase across the western Gulf of Mexico. However,
instability will remain insufficient for any thunderstorms as the
antecedent air mass across the Plains will be dry.
..Jewell.. 01/19/2019
 SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK
1227 AM CST Sat Jan 19 2019
Valid 191200Z - 201200Z
...Synopsis...  An upper trough and associated surface low are
expected to progress eastward from the lower MS Valley toward the
Mid-Atlantic coast today into tonight. A cold front will sweep into
the Gulf of Mexico in the wake of the surface low, with relatively
dry and breezy post-frontal conditions expected across portions of
south TX.
...South TX...  In the wake of the cold front, elevated fire
weather conditions are expected across portions of the Rio Grande
Valley/Deep South TX. RH values are expected to drop into the 20-30%
range this afternoon concurrent with sustained northwesterly winds
of 20-25 mph. The greatest threat for locally critical conditions
appears to be across the lower Rio Grande Valley, where slightly
warmer and drier conditions are possible compared to the rest of
the region, but confidence in a sufficient duration of critically
low RH remains too low for an upgrade.
..Dean.. 01/19/2019
...Please see for graphic product...
 SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK
1228 AM CST Sat Jan 19 2019
Valid 201200Z - 211200Z
...Synopsis...  Another strong upper trough will move inland
over California on Sunday, as an upper ridge shifts eastward over
the central/southern Rockies. At the surface, a weak trough will
develop in the lee of the Rockies by Sunday afternoon, resulting
in a return of low-level southerly/southwesterly flow over eastern
NM and west TX.
...Portions of Eastern NM/West TX...  Modification of an
initially cool and dry airmass will result in dry conditions
by Sunday afternoon across portions of eastern NM and west TX,
with minimum RH values of 15-25% expected across much of the
region. Low-level flow is expected to remain rather weak during
the day, with sustained winds largely expected to be in the 10-15
mph range, which should generally limit the fire weather threat.
Locally elevated conditions will be possible where slightly stronger
winds can develop, but confidence in where this might occur is too
low at this time to introduce an elevated area.
..Dean.. 01/19/2019
...Please see for graphic product...


... If forced to travel on an airplane, try and get in the cabin with the
Captain, so you can keep an eye on him and nudge him if he falls asleep or
point out any mountains looming up ahead ...
		-- Mike Harding, "The Armchair Anarchist's Almanac"


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