by SPC Forecast Products | Jan 18, 2020 | Weather and Emergency Alerts
No watches are valid as of Sat Jan 18 06:03:01 UTC 2020.
by SPC Forecast Products | Jan 18, 2020 | Weather and Emergency Alerts
MD 0062 CONCERNING FREEZING RAIN FOR NORTHEASTERN IL...CENTRAL/NORTHERN IN...WESTERN OH
Mesoscale Discussion 0062
NWS Storm Prediction Center Norman OK
1201 AM CST Sat Jan 18 2020
Areas affected...Northeastern IL...Central/Northern IN...Western OH
Concerning...Freezing rain
Valid 180601Z - 181000Z
SUMMARY...Greatest freezing rain potential will extend from
northeastern Illinois into western Ohio. Freezing rain rates could
exceed 0.05"/hr.
DISCUSSION...Well-defined warm conveyor has evolved from
MO-IL/IN-Lower MI. Strong isentropic ascent ahead of a pronounced
short-wave trough will continue through the night and a broad
corridor of precipitation should gradually shift from west to east
across the Mid-MS/OH Valley region. Strong warm advection has
gradually raised surface temperatures above freezing across much of
MO into central IL and substantial boundary-layer warming is
expected to change freezing rain to rain by 12z across much of IN.
Forecast soundings support this with strong warming at 850mb as
50-60kt LLJ strengthens across the OH Valley. Freezing rain threat
should linger across northeast IN into western OH through 12z.
..Darrow.. 01/18/2020
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...ILN...IWX...IND...LOT...ILX...
LAT...LON 41878783 41718654 41428588 40648359 39718382 39708629
40408767 41878783
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by SPC Forecast Products | Jan 18, 2020 | Weather and Emergency Alerts
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1148 PM CST Fri Jan 17 2020
Valid 181200Z - 191200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated thunderstorms are possible from south Texas into the
central Gulf Coast states today. The risk for severe weather is low.
...Synopsis...
A mid-level trough will progress eastward through the mid- and
upper-Mississippi Valley regions into the Great Lakes region today.
This feature is expected to lose amplitude with time. At the
surface, a strong cyclone will lift into the upper Midwest/Lower
Great Lakes during the afternoon and evening. An attendant cold
front will move southeastward, reaching into the northern/central
Gulf of Mexico by the end of the period. A warm-frontal boundary
will be positioned within southern Alabama/Mississippi into the
western Florida Panhandle.
With the strongest upper-level forcing for ascent remaining to the
north, only isolated thunderstorm development along/near the frontal
boundaries is expected. Boundary-layer dewpoints in the low- to
mid-60s F within the warm sector will support only modest buoyancy.
With the exception of areas near the warm front, deep-layer and
low-level shear will be relatively weak. A conditional threat for
marginal supercell structures during the afternoon/early evening may
develop in portions of the western Florida Panhandle that receive
greater surface heating. Should that occur, a brief tornado would be
possible with storms interacting with the warm front. However, given
the uncertainties regarding surface-based destabilization and narrow
window of potential, no severe probabilities will be added at this
time.
..Wendt.. 01/18/2020
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by SPC Forecast Products | Dec 19, 2019 | Weather and Emergency Alerts
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0139 PM CST Thu Dec 19 2019
Valid 201200Z - 211200Z
...NO CRITICAL AREAS...
Locally elevated fire-weather conditions are possible in a couple of
locations: 1) across portions of west Texas where northerly surface
flow will increase to 10-15 mph and RH values falling to around 20%
and 2) across coastal ranges of San Diego County, where an offshore
pressure gradient will foster areas of 20 mph winds with higher
gusts amidst 20% RH values. The marginality of these conditions and
fuel states in each region preclude any elevated delineations at
this time, though these regions will be re-evaluated in later
outlooks.
..Cook.. 12/19/2019
.PREV DISCUSSION... /ISSUED 0122 AM CST Thu Dec 19 2019/
...Synopsis...
High pressure and mostly light winds will dominate most of the CONUS
on Friday. Some dry conditions will be present in portions of
Arizona and New Mexico, but northerly winds will be light and fuels
are not all that dry. Therefore, no fire weather areas are
warranted.
...Please see www.spc.noaa.gov/fire for graphic product...
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by SPC Forecast Products | Dec 18, 2019 | Weather and Emergency Alerts
Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CST Wed Dec 18 2019
Valid 211200Z - 261200Z
...DISCUSSION...
...Day 4-5/Sat-Sun - FL and portions of the Southeast...
Medium range guidance is in somewhat better agreement compared to
this time yesterday with regards to the evolution of the southern
stream upper low/trough over the southern Plains on Saturday.
Differences still exist in timing and intensity of this feature, but
in general, the low is expected to track eastward across the Gulf
Coast states toward FL through the weekend. Strong shear will
develop ahead of the upper low from FL into parts of GA/SC. Strong
surface high pressure and east/northeasterly low level flow will
limit rich boundary layer moisture across the region initially.
However, a surface low is expected to develop near the northern Gulf
Coast and track eastward through the weekend, allowing moisture to
return northward while increasing low level shear. As a result, some
severe potential is possible this weekend. However, uncertainty in
the track and intensity of the surface low, as well as concerns over
the quality of thermodynamics, precludes inclusion of severe
probabilities at this time.
The remainder of the period will see an amplified upper ridge shift
from the western U.S. to the eastern U.S. by early next week. The
upper ridge will remain across the eastern half of the U.S. through
the end of the period, while a large-scale trough develops over the
West. As the trough develops over the West, expect chances for
thunderstorms to increase across portions of AZ/NM into the Plains
around Days 7/8-Tue/Wed, however, severe potential appears low.
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