RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Fri Mar 20 17:33:01 UTC 2026.
No Mesoscale Discussions are in effect as of Fri Mar 20 17:33:01 UTC 2026.
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1115 AM CDT Fri Mar 20 2026
Valid 201630Z - 211200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE UPPER OHIO VALLEY INTO THE CENTRAL APPALACHIANS...
...SUMMARY...
Strong to locally severe thunderstorms are possible across parts of
the Upper Ohio Valley and central Appalachians, mainly late this
afternoon into the evening.
...Upper Ohio Valley into the Central Appalachians...
Midday water-vapor imagery indicates a mid-level shortwave trough
over Lower Michigan as a belt of strong west-northwesterly flow is
maintained across the north-central U.S. eastward to the
Mid-Atlantic and New England coastal vicinity. This disturbance is
forecast to quickly move to the Delmarva/NJ by midnight.
The northern extent of a moisture plume, and an airmass still
undergoing modification over the Gulf Basin, will protrude northeast
into the upper OH Valley by late afternoon. Forecast guidance shows
surface dewpoints perhaps reaching near 50 deg F near the OH-WV-PA
border region towards 00z. Cold 500-mb temperatures and diurnal
heating will act to partially compensate for modest moisture and
contribute to weak buoyancy. Isolated to widely scattered
low-topped thunderstorms will probably develop along a
southeastward-moving cold front during the evening. Elongated
hodographs support updraft organization but the overall limited
moisture will act to constrain otherwise greater storm coverage.
Marginally severe hail and perhaps a couple of damaging gusts are
the primary hazards with the stronger storms.
..Smith/Mosier.. 03/20/2026
Read more
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1138 AM CDT Fri Mar 20 2026
Valid 211200Z - 221200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
TENNESSEE INTO PORTIONS OF NORTH AND SOUTH CAROLINA...
...SUMMARY...
Isolated strong to severe thunderstorms may produce hail to near 1
inch diameter Saturday afternoon and evening from eastern Tennessee
into portions of North and South Carolina.
...Tennessee into the Carolinas...
A modest midlevel shortwave trough will migrate southeast from the
Mid-Mississippi Valley to the Southeast within a broader
northwesterly upper flow regime on Saturday. Midlevel flow is not
forecast to be overly strong with this shortwave, with around 25-35
kt noted in forecast guidance. However, vertically veering wind
profiles within the lowest 2-3 km, and stronger northwesterly flow
above 500 mb will support effective shear magnitudes of around 25
kt. Forecast soundings also show elongated/straight hodographs.
Boundary layer moisture is forecast to remain modest, with surface
dewpoints generally in the 50s, with some areas across the TN Valley
seeing low 60s dewpoints. However, relatively steep midlevel lapse
rates near 7 C/km and cool temperatures aloft (near -15 C at 500 mb)
will support 500-1000 J/kg MLCAPE.
Given modestly favorable vertical shear and instability, combined
with weak large-scale ascent overspreading the region by peak
heating, a low risk for severe storms producing hail to around 1
inch diameter appears possible, and a level 1 of 5 (Marginal) risk
has been included with the Day 2 update.
..Leitman.. 03/20/2026
Read more
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1046 AM CDT Fri Mar 20 2026
Valid 201700Z - 211200Z
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EASTERN WYOMING...
Visible satellite data depicts clear skies, with boundary-layer
warming underway. Surface observations show temperatures reaching
the 60s F in spots, with RH dipping to 20 percent, and westerly
surface winds approaching 20 mph amid 25 mph gusts. Guidance
consensus suggests that boundary-layer mixing will continue into the
afternoon hours, resulting in overlapping widespread 15-20 percent
RH and 15-20 mph sustained westerly surface winds. As such, the
current Elevated and Critical highlights across the northern High
Plains into the northern Rockies have been maintained.
..Squitieri.. 03/20/2026
.PREV DISCUSSION... /ISSUED 0115 AM CDT Fri Mar 20 2026/
...Synopsis...
A persistent upper-level ridge will remain centered over the
Southwest today with modest northwest flow aloft across the
central/northern High Plains. Surface high pressure over the
Intermountain West coupled with lee troughing across the northern
Great Plains will continue to favor a downslope wind regime, with
dry and windy conditions forecast to support elevated to critical
fire weather concerns across portions of the central and northern
High Plains.
...Central/Northern High Plains...
Record warm temperatures continue across much of the West amid an
anomalously strong upper-level ridge centered across the Southwest.
With high pressure remaining in place across the Intermountain West
and lee troughing across the northern Great Plains, a continuing
downslope wind regime is forecast to yield sustained
west-northwesterly surface winds of 20-25 mph across portions of
central/eastern Wyoming. Poor overnight RH recoveries have been
noted via recent surface observations with further RH reductions to
10-20% forecast this afternoon. Coupled with receptive fuels, this
is expected to support critical fire weather conditions across
central/eastern Wyoming today. Elevated fire weather concerns are
also forecast across adjacent areas of the western Wyoming Basin and
portions of southwestern South Dakota and western Nebraska where
surface winds of 15-20 mph are expected to overlap minimum RH values
of 10-20%.
Fuels remain more marginal farther to the north across much of
southern Montana and portions of extreme southwestern North Dakota
and northwestern South Dakota; however, continued warm/dry
conditions have supported some drying of fine fuels along with
recent fire activity. Given this, elevated fire weather conditions
are expected this afternoon as RH values are forecast to range from
15-25% amid stronger sustained westerly winds of 15-25 mph. 40+
knots of 700 mb flow across this region coupled with deep boundary
layer mixing may also support occasional wind gusts of 30-40 mph.
...Central Nevada into southern Oregon...
Guidance continues to indicate localized potential for sustained
southwesterly surface winds of 10-15 mph this afternoon as the
surface pressure gradient tightens ahead of an approaching cold
front. With RH values forecast to fall to 10-15%, localized elevated
fire weather concerns may materialize across portions of southern
Oregon into central Nevada, especially in areas that favor
terrain-induced wind enhancements. However, widespread elevated
conditions are not expected at this time given marginal early season
fuel conditions and sporadic coverage of coincident elevated wind/RH
criteria.
...Please see www.spc.noaa.gov/fire for graphic product...
Read more
|
