WW 542 SEVERE TSTM MI WI LM LS 072050Z - 080300Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 542
NWS Storm Prediction Center Norman OK
350 PM CDT Fri Aug 7 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
The Upper Peninsula of Michigan
Northern Wisconsin
Lake Michigan
Lake Superior
* Effective this Friday afternoon and evening from 350 PM until
1000 PM CDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph possible
Isolated large hail events to 1.5 inches in diameter possible
SUMMARY...A broken line of thunderstorms should continue to develop
eastward along a cold front this afternoon and evening while posing
a threat for mainly scattered severe/damaging winds. Isolated hail
may occur with cells that develop ahead of the front.
The severe thunderstorm watch area is approximately along and 60
statute miles north and south of a line from 35 miles southwest of
Ironwood MI to 55 miles northeast of Escanaba MI. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU2).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 540...WW 541...
AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
27035.
...Gleason
WW 541 SEVERE TSTM IA 071840Z - 080300Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 541
NWS Storm Prediction Center Norman OK
140 PM CDT Fri Aug 7 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Central and Eastern Iowa
* Effective this Friday afternoon and evening from 140 PM until
1000 PM CDT.
* Primary threats include...
Scattered large hail and isolated very large hail events to 2
inches in diameter possible
Scattered damaging wind gusts to 70 mph possible
SUMMARY...A mix of supercells and bowing clusters should pose a
threat for both large hail and severe/damaging winds as they spread
east-southeastward this afternoon and evening. The largest
hailstones may reach up to 1.5-2 inches in diameter with any
sustained supercells, and peak gusts of 60-70 mph may occur with the
more intense line segments/clusters.
The severe thunderstorm watch area is approximately along and 75
statute miles east and west of a line from 25 miles north northeast
of Mason City IA to 35 miles east southeast of Knoxville IA. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU1).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 540...
AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
30030.
...Gleason
WW 540 SEVERE TSTM CT DC DE MD NJ NY PA VA WV CW 071720Z - 080100Z
WVZ000-CWZ000-080100-
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 540
NWS Storm Prediction Center Norman OK
120 PM EDT Fri Aug 7 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Southwest Connecticut
District Of Columbia
Delaware
Maryland
New Jersey
Southern New York
Eastern Pennsylvania
Northern Virginia
Far Eastern West Virginia
Coastal Waters
* Effective this Friday afternoon and evening from 120 PM until
900 PM EDT.
* Primary threats include...
Scattered damaging wind gusts to 65 mph likely
Isolated large hail events to 1 inch in diameter possible
SUMMARY...Loosely organized clusters should pose a threat for mainly
scattered damaging winds as they spread east-northeastward this
afternoon and evening. Isolated hail may also occur with the
stronger cores.
The severe thunderstorm watch area is approximately along and 65
statute miles east and west of a line from 55 miles north of Newark
NJ to 35 miles west southwest of Washington DC. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU0).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 55 knots. A few
cumulonimbi with maximum tops to 500. Mean storm motion vector
26025.
...Gleason
WW 0542 Status Updates
STATUS FOR WATCH 0542 HAS NOT BEEN ISSUED YET
WW 0541 Status Updates
STATUS REPORT ON WW 541
THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.
..JEWELL..08/07/26
ATTN...WFO...DVN...DMX...ARX...
STATUS REPORT FOR WS 541
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
IAC011-013-015-017-019-023-031-033-037-049-055-065-067-069-075-
079-081-083-089-091-095-099-103-105-107-113-115-121-123-125-127-
131-139-153-157-169-171-181-183-187-189-191-195-197-072140-
IA
. IOWA COUNTIES INCLUDED ARE
BENTON BLACK HAWK BOONE
BREMER BUCHANAN BUTLER
CEDAR CERRO GORDO CHICKASAW
DALLAS DELAWARE FAYETTE
FLOYD FRANKLIN GRUNDY
HAMILTON HANCOCK HARDIN
HOWARD HUMBOLDT IOWA
JASPER JOHNSON JONES
KEOKUK LINN LOUISA
MADISON MAHASKA MARION
MARSHALL MITCHELL MUSCATINE
POLK POWESHIEK STORY
TAMA WARREN WASHINGTON
WEBSTER WINNEBAGO WINNESHIEK
WORTH WRIGHT
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
WW 0540 Status Updates
000-072240-
STATUS REPORT ON WW 540
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 NE CHO TO
10 WNW BWI TO 20 WNW ILG TO 20 SE ABE TO 30 NW EWR TO 25 WSW POU.
FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1854
..MARSH..08/07/26
ATTN...WFO...OKX...LWX...PHI...CTP...BGM...
STATUS REPORT FOR WS 540
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
CTC001-072240-
CT
. CONNECTICUT COUNTIES INCLUDED ARE
FAIRFIELD
DEC001-003-005-072240-
DE
. DELAWARE COUNTIES INCLUDED ARE
KENT NEW CASTLE SUSSEX
DCC001-072240-
DC
. DISTRICT OF COLUMBIA COUNTIES INCLUDED ARE
DISTRICT OF COLUMBIA
MD 1855 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR NORTHERN WISCONSIN INTO UPPER MICHIGAN
Mesoscale Discussion 1855
NWS Storm Prediction Center Norman OK
0311 PM CDT Fri Aug 07 2026
Areas affected...northern Wisconsin into Upper Michigan
Concerning...Severe potential...Watch possible
Valid 072011Z - 072215Z
Probability of Watch Issuance...60 percent
SUMMARY...Scattered storms may develop across northern Wisconsin and
move into Upper Michigan later this afternoon. Large hail and
damaging gusts will be possible.
DISCUSSION...Visible imagery shows convection beginning to form
along the cold front as it moves into far northern WI and toward
southwestern parts of Lake Superior. While substantial high clouds
have overspread the warm sector, areas of heating exist, with
temperatures now into the low 80s F.
A special 18Z GRB sounding confirms steep lapse rates above the
capping inversion, with overall moderate instability. Deep-layer
shear is a bit marginal for supercells, but near 30 kt. Overall,
this setup should favor scattered cells/clusters, with periods of
hail and gusty winds. A supercell or two could produce hail at or
above golf ball size.
..Jewell/Gleason.. 08/07/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MQT...GRB...DLH...ARX...MPX...
LAT...LON 47468761 46988713 46558695 45988692 45518733 45188763
45008844 45168964 45739188 46239196 46619135 46809068
46878993 47498829 47468761
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
MD 1854 CONCERNING SEVERE THUNDERSTORM WATCH 540... FOR PARTS OF EASTERN PA...NORTHERN/CENTRAL NJ...SOUTHEASTERN NY...AND FAR WESTERN CT
Mesoscale Discussion 1854
NWS Storm Prediction Center Norman OK
0304 PM CDT Fri Aug 07 2026
Areas affected...Parts of eastern PA...northern/central
NJ...southeastern NY...and far western CT
Concerning...Severe Thunderstorm Watch 540...
Valid 072004Z - 072200Z
The severe weather threat for Severe Thunderstorm Watch 540
continues.
SUMMARY...The risk of scattered damaging wind gusts will continue
spreading east-northeastward across parts of Severe Thunderstorm
Watch 540.
DISCUSSION...A loosely organized band of thunderstorms is advancing
east-northeastward across eastern PA and southeastern NY this
afternoon, where there have been several reports of wind damage.
This activity will continue spreading east-northeastward into an
increasingly warm/unstable PBL (lower 90s temperatures amid
lower/middle 70s dewpoints). Steepened low-level lapse rates and the
well-established/strengthening cold pools will promote an increasing
risk of scattered damaging wind gusts over the next few hours. To
the north of Severe Thunderstorm Watch 540 in southeastern NY, a
narrow spatial overlap of sufficient/modest destabilization and
midlevel height falls will support a localized risk for damaging
thunderstorm wind gusts through the afternoon. A downstream watch is
not currently expected.
..Weinman.. 08/07/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OKX...ALY...PHI...BGM...
LAT...LON 40257575 40727538 41277484 41767455 42017446 42187411
42097371 41737343 41447331 40977349 40297403 39787476
39657520 39717550 39927568 40257575
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0225 PM CDT Fri Aug 07 2026
Valid 072000Z - 081200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
IOWA...NORTHERN WISCONSIN INTO THE UPPER PENINSULA OF MICHIGAN...AND
THE MID-ATLANTIC...
...SUMMARY...
Isolated to scattered severe thunderstorms are possible across parts
of the Upper Midwest/Great Lakes this afternoon and evening, with
large to very large hail and severe winds the main threats.
Thunderstorms capable of scattered damaging winds may also occur
over portions of the Mid-Atlantic.
...20z Update...
Adjustments were made to the D1 Convective Outlook to trim
probabilities behind the cold front across Minnesota/Iowa and behind
morning/early afternoon convection across Kansas/Oklahoma. The
Marginal Risk was shifted southward across Oklahoma/Arkansas to
account for recent trends in storm/outflow evolution and resulting
increasing potential for damaging wind downstream.
A Marginal Risk was added across portions of southwestern New Mexico
into far western Texas. Across this region, a very deeply mixed and
hot boundary layer will support outflow dominant storms. Hi-res
guidance suggests that storms may produce strong to severe outflow
winds across this region later this afternoon.
See previous discussion below for more information.
..Thornton.. 08/07/2026
.PREV DISCUSSION... /ISSUED 1106 AM CDT Fri Aug 07 2026/
...Upper Midwest/Great Lakes...
Thunderstorms are ongoing along/ahead of a cold front late this
morning from the MN Arrowhead southwestward into southern
MN/northern IA. While there are still uncertainties regarding
convective evolution this afternoon and evening, it appears
increasingly probable that two mesoscale corridors of greater severe
potential will exist: one across southern MN into IA, and another
across northern WI into the U.P of MI. In general, the severe risk
today will be aided by a mid/upper-level trough advancing
east-southeastward across these regions in tandem with a 35-50 kt
west-northwesterly mid-level jet.
Thunderstorms are expected to further increase in coverage and
intensity along the eastward-advancing cold front this afternoon
across parts of northern WI into the western U.P of MI. While latest
NAM/RAP forecast soundings across this area suggest low-level
moisture remains fairly shallow/limited, mostly clear conditions are
noted on recent visible satellite imagery. Resultant moderate
instability and gradually strengthening deep-layer shear with the
approach of the mid/upper-level trough will aid in thunderstorm
organization. Small clusters/bowing line segments will probably be
the dominant mode given the linear forcing of the cold front, with
enhanced low/mid-level flow aiding the risk for scattered
severe/damaging winds. A Slight Risk has been added for parts of
northern WI into the U.P of MI given increased confidence in this
scenario occurring.
Farther south, generally elevated convection is ongoing across
southern MN into northern IA. The 12Z observed sounding from MPX
showed fairly steep low/mid-level lapse rates in the 850-530 mb
layer, which along with 35-40 kt of effective bulk shear and around
2000 J/kg of MUCAPE may continue to support a threat for severe hail
with this activity in the short term. Even though cloud cover
remains prevalent across these areas late this morning, a corridor
of moderate to locally strong instability is still forecast to
develop this afternoon across parts of eastern NE into IA ahead of
the cold front. Current expectations are for multiple surface-based
supercells and/or bowing clusters to develop along/ahead of the
front in southern MN, and then spread southeastward across IA
through the late afternoon/early evening. A threat for both large
hail and damaging winds should exist with this activity, and a
Slight Risk has been introduced where confidence is greater that
robust convection will occur. 2+ inch diameter hail and perhaps a
tornado also appear possible with any surface-based supercell, even
though low-level flow will not be overly strong.
...Ohio Valley into the Mid-Atlantic...
Between upper troughing over central Canada/the Upper Midwest and
upper ridging over the western Atlantic, around 20-30 kt of
southwesterly mid-level flow will exist today from the OH Valley
into the Mid-Atlantic and Northeast. Greater destabilization and
steepening of low-level lapse rates are anticipated this afternoon
across the Mid-Atlantic, where recent visible satellite imagery
shows generally clear skies. Loosely organized cells/clusters that
initially develop across the higher terrain of the central
Appalachians should spread into the Mid-Atlantic coastal plain
through the afternoon/evening, while posing a threat for scattered
damaging winds up to 50-60 mph and perhaps marginally severe hail.
Across the OH Valley, somewhat weaker mid-level flow may tend to
limit updraft organization. Still, some potential for clustering and
isolated damaging winds may exist downstream of ongoing convection
where greater destabilization can ocur. Have therefore expanded the
Marginal Risk across much of the OH Valley to account for this
possibility.
...Southern/Central Plains into the Ozarks...
Elevated thunderstorms posing an isolated hail threat in southeast
KS late this morning should further diminish into the early
afternoon as a southwesterly low-level jet gradually weakens. To the
south and east of this activity, a hot and unstable airmass will
exist this afternoon across OK into parts of southern MO and AR.
Although details regarding convective evolution remain unclear, it
is possible that robust thunderstorms develop/continue on the
outflow from this morning's activity, or near multiple MCVs present
from earlier convection. Isolated strong to severe winds appear
possible, even though deep-layer shear should remain weak. The
Marginal Risk has been expanded eastward and connected to the risk
area in the OH Valley. Other isolated thunderstorms posing some
severe wind threat may develop this afternoon farther west across
eastern NM into the OK/TX Panhandles.
...Arizona...
Modest east-southeasterly mid-level flow will persist today over AZ
to the south of a mid/upper-level anticyclone centered over the Four
Corners. Widely scattered convection should develop over the
Mogollon Rim and the higher terrain in southeast AZ this afternoon,
and gradually spread into the lower deserts this evening. Given the
very well-mixed boundary layer and weak to locally moderate
instability expected to be in place ahead of these thunderstorms,
have maintained low severe wind probabilities.
...Northern Nebraska/Southern South Dakota...
Elevated thunderstorms may develop across parts of northern NE and
southern SD late tonight/early Saturday morning as isentropic ascent
increases in tandem with modest strengthening of a southerly
low-level jet. Low-level moistening beneath steepening mid-level
lapse rates should support sufficient MUCAPE for robust updrafts,
although confidence in overall coverage remains low due to
weak/nebulous large-scale ascent. Regardless, strong shear in the
cloud-bearing layer across this area should promote organized
convection capable of producing isolated severe hail.
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1231 PM CDT Fri Aug 07 2026
Valid 081200Z - 091200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS WITHIN PARTS OF
THE CENTRAL AND NORTHERN PLAINS INTO THE MID/UPPER MISSISSIPPI
VALLEY...PARTS OF CENTRAL/SOUTHEAST ARIZONA...PARTS OF THE
MID-ATLANTIC...
...SUMMARY...
Thunderstorms with severe wind gusts will be possible Saturday
afternoon and evening across parts of the central and northern
Plains southeastward into the lower to mid Missouri Valley.
Additional strong to severe storms are possible in the Mid-Atlantic
and central/southeast Arizona.
...Central Plains into Upper Mississippi Valley...
A complex forecast scenario continues to be evident on Saturday.
Models continue to show a focused low-level jet into western
Nebraska/South Dakota early Saturday morning. Some convection may be
associated with this feature, though storm coverage is not clear.
Depending on the evolution of that activity, some risk for severe
winds and large hail is possible. Storm coverage will largely
dictate how long early morning activity can persist into the
afternoon as warming temperatures aloft are expected during the day.
A strong enough cold pool would have to evolve in order to allow
convection to propagate southeastward with the low-level jet
decreasing into the late morning/early afternoon. Convective
development during the afternoon is far from certain given the
aforementioned capping that will exist. Forcing for ascent will be
weak as well. Some guidance does show some thunderstorm development
along the cold front in parts of the eastern Dakotas/western
Minnesota. The Marginal has been expanded into these areas to
account for this potential hail/wind threat.
By late afternoon/early evening, an intensifying low-level jet will
be focused within the Mid-Missouri Valley. Storm development will
become more likely along the warm front as this occurs. However, the
strongest activity may not form until around 06Z. This reduces
confidence in how severe the activity will be, particularly in terms
of severe wind. Again, the Marginal was expanded to the north/east
to encompass the various model solutions. Large hail would be
possible even with elevated storms given sufficient shear and steep
mid-level lapse rates. A greater threat for severe wind gusts may
still develop, but this is conditional on enough of a cold pool
developing. Confidence remains rather low.
...Mid-Atlantic...
A modest, low-amplitude shortwave trough will be favorably timed
with afternoon heating. Widely scattered to scattered storms are
possible ahead of this feature. Deep-layer shear will not be overly
strong, but should be sufficient for strong/marginally severe cells
and clusters. Storm coverage is not certain given the veered,
deep-layer flow, but most model guidance suggests locally greater
storm coverage from northern Virginia into eastern Pennsylvania and
adjacent New Jersey. Wind damage will be the main concern.
...Arizona...
Low 60s F dewpoints are forecast to remain within the lower desert
areas. Strong heating should promote destabilization during the
afternoon/early evening. Most CAM guidance suggests that one or more
clusters will develop on the Mogollon Rim and move west/southwest.
Severe wind gusts will be possible with this activity.
..Wendt.. 08/07/2026
SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0333 PM CDT Fri Aug 07 2026
Valid 091200Z - 101200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE BLACK
HILLS INTO MID-MISSOURI/MISSISSIPPI VALLEYS AND PARTS OF THE
SOUTHERN GREAT LAKES...CENTRAL/EASTERN MAINE...
CORRECTED FOR TYPO
...SUMMARY...
Thunderstorms with isolated severe wind gusts and hail will be
possible Sunday afternoon and evening from parts of the central and
northern Plains east-southeastward into the southern Great Lakes
region. Additional strong to severe storms are possible in Maine.
...Black Hills into parts of the lower Great Lakes...
Forecast uncertainty remains high. A moderate to strong low-level
jet is forecast to persist into early Sunday morning. This feature
will generally be focused into the Mid-Mississippi Valley region. It
is probable that some convection will be ongoing during the early
morning with some risk for large hail and possibly isolated damaging
winds. While the low-level jet will weaken to some extent into the
mid/late morning, modest 850 mb theta-e advection will continue and
may promote stronger development along the outflow from this early
activity. Steep mid-level lapse rates and 40-50 kt of effective
shear on the western flank of the outflow would favor severe storms.
Similar to Saturday, additional storms could form as the low-level
jet intensifies Sunday night. Large hail would be the most likely
hazard as these storms would tend to be slightly elevated.
Farther west, storm development is much more uncertain. Warm
temperatures aloft will lead to capping within the Plains. A surface
low is forecast to develop which may provide local enhancement to
convergence, but the location and strength of this feature varies
model to model. Mid-level ascent will be subtle at best. The ECMWF
is the most aggressive with afternoon development. That solution
suggests development near the surface low/Black Hills with a
southeastward moving complex. While an increase in probabilities
would be needed in this scenario, confidence is not high.
...Maine...
Moderate mid-level winds will continue across much of the Northeast.
Ahead of a cold front, upper 60s to low 70s F dewpoints will support
1500-2000 J/kg MLCAPE. Shear will be modest, but hodographs will be
long. A few marginal supercell structures are possible with an
accompanying risk for isolated wind damage and marginal hail.
..Wendt.. 08/07/2026
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1140 AM CDT Fri Aug 07 2026
Valid 071700Z - 081200Z
The forecast remains on track for elevated fire weather conditions
across much of the northwestern CONUS, and isolated dry
thunderstorms in southern Nevada and southwest Utah. Satellite
imagery portrays a dense layer of wildfire smoke over much of the
Intermountain West, which may limit daytime high temperatures by a
few degrees across the Elevated risk area. Vertical mixing and
strengthening upper-level flow will contribute to gusty surface
winds and critically low RH values this afternoon amid an
exceptionally dry fuelscape (ERCs exceeding the 95-98th percentile),
generating yet another day of heightened fire concerns. Surface
winds of 15 mph or greater and RH values of 5-15% will further
exacerbate numerous large fires across the Pacific Northwest and
northern Rockies, alongside any new starts. See the previous
discussion for more information.
..Elizalde-Garcia.. 08/07/2026
.PREV DISCUSSION... /ISSUED 0218 AM CDT Fri Aug 07 2026/
...Synopsis...
A large mid-level ridge will remain centered near the Four Corners
region of the US today, with the strongest mid-level flow across the
CONUS found along the US-Canadian border. Monsoonal moisture will
continue to infiltrate portions of southern California, Nevada, and
Utah, bringing with it chances of afternoon thunderstorms atop a dry
boundary layer.
... Northern Intermountain West ...
Modest westerly mid-level flow will be found across the region
today. As diurnal heating contributes to deep vertical mixing,
surface winds around 15 mph with stronger gusts are likely.
Additionally, the deep mixing will contribute to relative humidity
falling to perhaps as low as 5% across favored areas across the
region, with minimum afternoon relative humidity between 10-15%
elsewhere. Given very receptive fuels across the area, elevated to
locally critical fire weather conditions are likely.
... Southern Nevada and Southwest Utah ...
Thunderstorms are expected along the western periphery of a
mid-level ridge where the advancing monsoonal moisture will be
found. The northern edge of the monsoonal moisture will likely be
constrained to the mid and upper levels initially, leaving a very
dry sub-cloud layer in place. High-based thunderstorms that do
develop here will likely feature significant evaporation of falling
precipitation leading to little, if any, appreciable rainfall.
Additionally, evaporative cooling beneath the cloud layer will
result in gusty/erratic thunderstorm outflows.
... California ...
Localized fire weather concerns will be possible across portions of
California, particularly the interior portions of Southern
California. Here, hot temperatures into the 110Fs will contribute to
relative humidity into the single digits. However, relatively calm
winds should limit the overall elevated fire weather conditions to a
more localized nature.
...Please see www.spc.noaa.gov/fire for graphic product...
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0206 PM CDT Fri Aug 07 2026
Valid 081200Z - 091200Z
Only minor adjustments were made to the risk areas based on recent
guidance. Otherwise, the forecast remains on track for expansive
elevated fire weather conditions across the northwestern CONUS, and
dry thunderstorms in the Sierra Nevada and Great Basin. See the
previous discussion for more information.
..Elizalde-Garcia.. 08/07/2026
.PREV DISCUSSION... /ISSUED 0218 AM CDT Fri Aug 07 2026/
...Synopsis...
A large mid-level ridge will remain centered near the Four Corners
region of the US on Saturday, with the strongest mid-level flow
across the CONUS once again found along the US-Canadian border. A
weak mid-level vorticity maximum will move across the Pacific
Northwest, however mid-level flow enhancement looks modest with this
feature. At the same time, monsoonal moisture will continue to
advance northward across the West, bringing with it chances of
afternoon thunderstorms atop a dry boundary layer.
... Northern Intermountain West and Pacific Northwest ...
Modest westerly mid-level flow will be found across the region
Saturday, especially closer to the Canadian border. Another
potential area of enhanced mid-level flow could develop across
northern Oregon and much of Washington in association with a passing
mid-level vorticity maximum.
Common across most of the region will be the development of surface
winds around 15 mph with higher gusts as diurnal heating and the
associated deep vertical mixing bring down some of that enhanced
mid-level flow. The deep mixing will also contribute to relative
humidity falling to perhaps as low as 5% across favored areas across
the region, with minimum afternoon relative humidity between 10-15%
elsewhere. Given very receptive fuels across the area, elevated to
locally critical fire weather conditions are likely.
One potential area for a possible upgrade will be across portions of
the Pacific Northwest as the mid-level vorticity maximum moves
across the area. Despite significant smoke plumes potentially
limiting vertical mixing, terrain favored areas such as mountain
gaps in the Cascades and within eastern portions of the Columbia
River gorge, may see periods of higher sustained winds, leading to a
window of potentially critical conditions. Confidence is increasing
in this scenario, but still remains too low to highlight at this
lead time.
... California Sierras, Southern/Central Nevada, and much of Utah
...
Similar to Friday, thunderstorms are expected along the western
periphery of a mid-level ridge where the advancing mid- and
upper-level monsoonal moisture will be found. Beneath this moist
plume, a very dry sub-cloud layer will support significant
evaporation of falling precipitation leading to little, if any,
appreciable rainfall. Evaporative cooling beneath these dry
thunderstorms will result in gusty/erratic thunderstorm outflows.
...Please see www.spc.noaa.gov/fire for graphic product...
|
