Severe Storms

WW 607 SEVERE TSTM GA NC SC 072030Z - 080400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 607 NWS Storm Prediction Center Norman OK 430 PM EDT Mon Aug 7 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Central and Eastern Georgia North Carolina South Carolina * Effective this Monday afternoon from 430 PM until Midnight EDT. * Primary threats include... Widespread damaging winds likely with isolated significant gusts to 75 mph possible Isolated large hail events to 1 inch in diameter possible A tornado or two possible SUMMARY...Storms may intensify and become severe initially across central Georgia into the South Carolina Piedmont, but more so, well-organized linear cluster of storms ongoing late this afternoon across northern Georgia and the western Carolinas will steadily move eastward through this evening. Widespread damaging winds are expected. The severe thunderstorm watch area is approximately along and 90 statute miles east and west of a line from 45 miles northeast of Rocky Mount NC to 15 miles east southeast of Macon GA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU7). 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 599...WW 600...WW 601...WW 602...WW 603...WW 604...WW 605...WW 606... AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 65 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 27035. ...Guyer Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Mon Aug 07 2023 Valid 072000Z - 081200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS SOUTHERN WEST VIRGINIA INTO WESTERN AND NORTHERN VIRGINIA...MARYLAND...AND FAR SOUTHERN PENNSYLVANIA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE CENTRAL AND SOUTHERN HIGH PLAINS... ...SUMMARY... A severe weather outbreak is expected across parts of the eastern U.S. this afternoon into the early evening with widespread and locally destructive damaging winds and tornadoes as the greatest threats, especially across the southern/central Appalachians and Mid-Atlantic States. ...Discussion... Only notable change this convective outlook update is to remove severe probabilities in wake of thunderstorm bands and where low-level flow has strongly veered to westerly over much of the OH Valley into portions of the upper TN Valley. Elsewhere, little change was made to the previously issued forecast. ..Smith.. 08/07/2023 .PREV DISCUSSION... /ISSUED 1140 AM CDT Mon Aug 07 2023/ ...Southeast to the Upper Ohio Valley to the Mid-Atlantic States... Owing to a very moist/unstable air mass and very strong winds aloft for August, a widespread severe-weather risk is already unfolding at late morning/midday across a broad region, initially west of the Appalachians spine. Refer to ongoing Watches and Mesoscale Discussions for the latest regional details. A shortwave trough over the Lower Ohio Valley will continue to advance toward the northern Appalachians by evening. A pair of 500-mb speed maxima from 55-65 kts are expected to be centered by late afternoon across eastern KY/TN and southern WV into western VA/NC, and separately over the Mid-South. Peak flow within an expansive 700-mb jet should be centered between the 500-mb maxima across the TN Valley. A plume of large potential buoyancy supported by high PW and steep mid-level lapse rates, and centered over the Mid-South/TN Valley will expand east-northeast towards the central/southern Appalachians with an expansive swath of MLCAPE from 2000-3500 J/kg expected by peak heating. Ongoing storms across eastern portions of TN/KY and WV/southern OH will progress into an increasingly favorable thermodynamic and kinematic environment downstream, yielding many supercells capable of producing large hail, damaging winds, and tornadoes. Upscale growth into several linear clusters with embedded supercells is anticipated this afternoon as convective coverage becomes widespread from PA/MD south-southwest across the southern Appalachian states. Forecast soundings suggest the greatest tornado threat will probably exist across eastern KY/TN northeast across southern/eastern WV, western VA, central MD and into southeast PA. Given the supercell wind profiles, significant severe wind gusts will also be possible on a localized basis. Across the Southeast, aided by a separate mid-level speed max, linear clusters of storms will continue to develop and spread generally eastward across parts of the TN Valley toward the southern Appalachians and Carolinas, with damaging winds as the most common hazard. ...Central High Plains... No changes warranted for this region. A 50-60 kt mid-level speed max should become centered near the NE/CO/KS border vicinity by late afternoon with approach of a low-amplitude shortwave impulse currently over southeast ID. This will overlap a confined north/south-oriented corridor of moderate buoyancy with MLCAPE of 1500-2500 J/kg along a lee trough across the similar tri-state area. Initial high-based thunderstorm development is anticipated off the higher terrain of CO/WY and will intensify as it impinges on the larger buoyancy during the early evening. A few supercells with very large hail will be possible along with a meso-beta scale corridor favorable for a tornadic supercell or two. Clustering of supercells may yield a short-duration uptick in severe wind gust potential across parts of western KS before convection spreads away from the relatively narrow instability plume and encounters increasing MLCIN after sunset. ...Southern High Plains... A wind-driven Slight Risk has been introduced for portions of eastern New Mexico into the Texas South Plains for later this afternoon and evening. Strong westerlies, particularly by August standards, and a hot/well-mixed boundary layer should support at least some severe storms capable of severe-caliber wind gusts. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Mon Aug 07 2023 Valid 081200Z - 091200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF CENTRAL AND NORTHWESTERN TEXAS... A Critical risk was added into portions of central and northwestern Texas on Tuesday. Deepening low pressure across the southern Plains will lead to an increase in southerly surface winds through the day Tuesday. Sustained winds near 15 mph (gusting 20-25 mph) will overlap afternoon relative humidity reductions around 15-25 percent. Winds may increase to around 15-20 mph (gusting 20-30 mph) amid slowly increasing relative humidity into the evening as the low continues to deepen and moisture moves north and west. Given the extremely dry state of fuels and multiple ongoing large fires, the Critical risk is supported though winds may be borderline within some portion of the highlighted Critical area. ..Thornton.. 08/07/2023 .PREV DISCUSSION... /ISSUED 0137 AM CDT Mon Aug 07 2023/ ...Synopsis... Fire weather concerns will continue to be focused across the Four Corners region and portions of central to southwest Texas as an upper trough approaches the central Rockies. Short to medium-range guidance shows fairly good agreement in the deepening of an upper disturbance (noted over the northeast Pacific in early-morning water-vapor imagery) over the next 48 hours. This will support pressure falls along the High Plains, resulting in strengthening pressure gradient winds over the Four Corners and southern Plains where fuels remain dry. ...Four Corners... Surface winds are forecast to increase to 15-20 mph across a large swath of the greater Four Corners region. The strongest winds will likely occur over parts of northern AZ to southern/eastern UT under a belt of stronger mid-level flow with gusts up to 30-35 mph possible. Antecedent dry conditions and mostly sunny skies will favor RH reductions into the single digits to low teens across UT, western CO, and northern AZ with gradually improving moisture quality with southward extent into central AZ/NM. As with Monday, the southern and eastern extent of the fire weather threat is uncertain due to 1) an influx of monsoonal moisture from southern AZ and 2) the potential for afternoon showers/thunderstorms - especially over northeast NM where 1-3 hours of elevated conditions may develop prior to convective initiation. Regardless, several hours of elevated conditions appears likely with critical conditions possible over northern AZ/southern UT. ...Texas... Surface gradient winds will steadily increase through the day Tuesday as the lee trough/cyclone deepens. While there is some model spread in the strength of the low over western TX, ensemble guidance shows a reasonably strong signal for sustained winds near 15 mph (gusting to 20-25 mph) by peak heating. With forecast highs near 105 F, RH minimums near 20-30%, and critically dry fuels already in place, elevated to locally critical fire weather conditions are probable across a large swath of central to southwest TX. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Mon Aug 07 2023 Valid 081200Z - 091200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS NORTHEAST COLORADO...SOUTHWEST NEBRASKA...AND FAR NORTHWEST KANSAS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL MISSISSIPPI EASTWARD INTO SOUTHERN GEORGIA... ...SUMMARY... Scattered severe thunderstorms are possible across portions of the central High Plains Tuesday afternoon into Tuesday night. Large to very large hail along with a risk for a tornado and widely scattered severe gusts will be the potential hazards. ...Synopsis... Water-vapor imagery midday Monday shows a potent mid-level shortwave trough over the Pacific Northwest. This feature is forecast to be over the northern Intermountain region Tuesday morning and move east-southeast through the central Rockies during the period. Farther east, a mid-level trough over the Lower Great Lakes southward into the Mid-Atlantic states will pivot eastward and be located to the east of the New England coast by late Tuesday night. At the surface, low pressure near Lake Ontario will shift northeast along the St. Lawrence Valley. A cold front attendant to the low will develop eastward across southern New England through the day and offshore the northeast Atlantic coast during the evening/overnight. The southern extent of the front will stall over South Carolina. Southerly low-level flow will maintain a very moist airmass from the central Plains into the Southeast. ...Central Plains... Large-scale ascent associated with the aforementioned disturbance will overspread the central High Plains by mid-late afternoon. Low-level upslope flow will maintain a moist airmass from northwest KS towards the Cheyenne Ridge and feature dewpoints ranging through the 50s and into the 60s over northwest KS/southwest NE. Steep 700-500 mb lapse rates near 8 C/km atop the moist boundary-layer will support MLCAPE around 2000-3000 J/kg. Elongated hodographs will favor supercells with the stronger updrafts through the early evening. The relatively moist conditions centered over northeast CO could yield a focus risk for a tornado during the early evening, in addition to the threat for large to very large hail (diameters 2 to 3 inches). A 30-kt southerly LLJ is forecast to develop during the evening/overnight with the terminus located within an 850-mb moist axis. Considered higher severe-wind probabilities adjoining to the east of the 30-percent severe hail probabilities but uncertainty remained high regarding the convective morphology/orientation of storms as the activity moves into north-central KS/southern NE. ...Southeast... Residual outflow from convection in the Day 1 period will likely reside from northern MS into central AL/GA. This will result in differential heating ahead of convection expected to be ongoing across eastern OK/AR Tuesday morning in response to a vorticity maximum migrating through northwesterly flow aloft. As this convectively enhanced vorticity max and related MCV shifts east by early afternoon, thunderstorm are expected to increase rapidly intensify from central MS east into AL during the early-mid afternoon. An organized cluster/MCS is forecast to spread east across central/southern AL/GA during the afternoon and reach southern GA by early evening. Very high PW (2+ inches) and around 4000 J/kg MLCAPE forecast downstream of the evolving thunderstorm complex will likely result in isolated severe gusts and at least widely scattered wind damage. ...Southern New England... Storms will likely be ongoing Tuesday morning in a warm advection band ahead of the surface cold front. Backed low-level winds and proximity to the surface low will result in 0-1 km SRH around than 250 s2/m2. Weak lapse rates will limit updraft intensity, but very moist low-levels coupled with the low-level shear will support an environment conditionally favorable for storm rotation. The severe threat will probably diminish by midday as the warm advection-related storms shift northeast and move into the adjacent Atlantic waters. ..Smith.. 08/07/2023 Read more

MD 1869 CONCERNING SEVERE THUNDERSTORM WATCH 596... FOR SOUTHEAST GEORGIA INTO FAR SOUTHERN SOUTH CAROLINA
Mesoscale Discussion 1869 NWS Storm Prediction Center Norman OK 0524 PM CDT Sun Aug 06 2023 Areas affected...Southeast Georgia into far southern South Carolina Concerning...Severe Thunderstorm Watch 596... Valid 062224Z - 070030Z The severe weather threat for Severe Thunderstorm Watch 596 continues. SUMMARY...Damaging winds will remain possible into the evening hours as storms approach the Georgia/South Carolina coast; however, this threat will likely remain fairly limited. Downstream watch issuance is not expected. DISCUSSION...Ongoing thunderstorm clusters/lines across central to eastern Georgia have largely become outflow dominant over the past few hours. With cell motions to the east - orthogonal to the outflow propagation vector - new development along these boundaries is uncertain across central GA. Further east, a more easterly cold-pool motion is allowing for new cell development within an unstable air mass (SBCAPE estimates up to 2000-3000 J/kg). Forecast soundings from this region appear favorable for wet downbursts capable of damaging winds. The expectation over the next hour is for continued cell development along/behind the eastward-moving outflow with the potential for sporadic damaging winds. This activity may persist to the GA/SC coast, but storm longevity/organization will remain too limited to pose a more robust threat. Consequently, downstream watch issuance is not anticipated. ..Moore.. 08/06/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CHS...CAE...JAX...FFC... LAT...LON 32448275 32688223 33068170 33128126 33028076 32698046 32358043 31828085 31448105 31378119 31428188 31858254 32148284 32278285 32448275 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0455 PM CDT Sun Aug 06 2023 Valid 081200Z - 141200Z ...Central/Southwestern Texas... Very hot and dry conditions across central/southwestern Texas have led to critically dry fuels with an increase in fire activity. On Tuesday, a surface low will develop across the Southern Plains and deepen into Wednesday morning. Increasing surface winds will be likely into the afternoon/evening across central/southwestern Texas. A developing low-level jet will bring sustained winds 20-25 mph late D3 -Tuesday through D4 - Wednesday morning with moisture steadily increasing from the southeast. Relative humidity will continue to hover near 20-25 percent much of Tuesday evening before better moisture return begins. Afternoon mixing will allow relative-humidity reductions on D4 - Wednesday to 15-20 percent but winds should decrease below Critical thresholds through the day. Elevated fire weather concerns will continue each day through the extended period, as dry conditions and more warm temperatures continue each afternoon under lighter winds. ...Southwest... Dry westerly flow will persist across northern Arizona, southern Utah, southwestern Colorado, and north/central New Mexico on D3 - Tuesday. Afternoon relative-humidity reductions to 15-20 percent (as low as 5-10 percent across southern Utah) will overlap sustained winds 10-20 mph. Elevated to locally Critical fire weather conditions will be possible. At present, inclusion of a 70 percent Critical area is limited by unknowns in the duration and coverage of Critical winds. In addition, moisture will be steadily increasing beneath the Southwest high Tuesday into Wednesday across Arizona and western New Mexico. This will be a return of shower and thunderstorm activity Tuesday and Wednesday. Elevated fire weather conditions will become more sparse on Wednesday as a result, mainly confined to central New Mexico. Winds decrease beneath the building high beyond Wednesday with increasing moisture and potential uptick in monsoon thunderstorm activity. ..Thornton.. 08/06/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0597 Status Updates
STATUS REPORT ON WW 597 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 NE COU TO 35 SSW UIN TO 15 WNW UIN TO 35 WSW BRL TO 15 NE OTM. ..LYONS..08/06/23 ATTN...WFO...DVN...LSX...ILX...PAH... STATUS REPORT FOR WT 597 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC001-005-009-013-017-021-023-025-027-029-033-035-047-049-051- 057-061-067-071-079-081-083-101-107-109-115-117-119-121-125-129- 133-135-137-139-145-149-157-159-163-167-169-171-173-185-187-189- 191-062240- IL . ILLINOIS COUNTIES INCLUDED ARE ADAMS BOND BROWN CALHOUN CASS CHRISTIAN CLARK CLAY CLINTON COLES CRAWFORD CUMBERLAND EDWARDS EFFINGHAM FAYETTE FULTON GREENE HANCOCK HENDERSON JASPER JEFFERSON JERSEY LAWRENCE LOGAN MCDONOUGH MACON MACOUPIN MADISON MARION MASON MENARD MONROE MONTGOMERY MORGAN MOULTRIE PERRY PIKE RANDOLPH RICHLAND ST. CLAIR SANGAMON SCHUYLER SCOTT SHELBY WABASH WARREN WASHINGTON WAYNE Read more

WW 597 TORNADO IA IL MO 062015Z - 070300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 597 NWS Storm Prediction Center Norman OK 315 PM CDT Sun Aug 6 2023 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Southeast Iowa Western and South-Central Illinois Eastern Missouri * Effective this Sunday afternoon and evening from 315 PM until 1000 PM CDT. * Primary threats include... A couple tornadoes possible Scattered large hail and isolated very large hail events to 2 inches in diameter possible Scattered damaging wind gusts to 70 mph possible SUMMARY...Scattered strong to severe thunderstorms are expected to develop this afternoon, initially across southeast Iowa, far eastern Missouri and western Illinois. This includes supercells capable of large hail and a tornado risk. Storms should increase and move into/across much of south-central Illinois by evening, with damaging winds also a possibility. The tornado watch area is approximately along and 70 statute miles north and south of a line from 40 miles west northwest of Quincy IL to 45 miles southeast of Mattoon IL. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU7). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and 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. && OTHER WATCH INFORMATION...CONTINUE...WW 595...WW 596... AVIATION...Tornadoes and 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 550. Mean storm motion vector 27025. ...Guyer Read more

WW 0596 Status Updates
STATUS REPORT ON WW 596 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 E CHA TO 30 NNW ATL TO 30 ENE ATL TO 35 WNW AGS TO 10 N AGS TO 10 WSW CAE. ..LYONS..08/06/23 ATTN...WFO...FFC...CAE... STATUS REPORT FOR WS 596 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS GAC009-015-021-023-033-035-045-047-053-055-063-077-079-083-097- 107-113-115-125-129-141-143-145-149-151-153-159-163-167-169-171- 175-193-197-199-207-215-217-223-225-231-233-237-249-255-263-269- 283-285-289-293-295-301-303-313-319-062240- GA . GEORGIA COUNTIES INCLUDED ARE BALDWIN BARTOW BIBB BLECKLEY BURKE BUTTS CARROLL CATOOSA CHATTAHOOCHEE CHATTOOGA CLAYTON COWETA CRAWFORD DADE DOUGLAS EMANUEL FAYETTE FLOYD GLASCOCK GORDON HANCOCK HARALSON HARRIS HEARD HENRY HOUSTON JASPER JEFFERSON JOHNSON JONES LAMAR LAURENS MACON MARION MERIWETHER MONROE MUSCOGEE NEWTON PAULDING PEACH PIKE POLK PUTNAM SCHLEY SPALDING TALBOT TAYLOR TREUTLEN TROUP TWIGGS UPSON Read more

WW 596 SEVERE TSTM GA SC 061935Z - 070100Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 596 NWS Storm Prediction Center Norman OK 335 PM EDT Sun Aug 6 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northwest and Central Georgia Western South Carolina * Effective this Sunday afternoon and evening from 335 PM until 900 PM EDT. * Primary threats include... Scattered damaging wind gusts to 65 mph possible SUMMARY...Clusters of storms will continue to move generally eastward across the region within a moist/unstable environment, with damaging winds possible. The severe thunderstorm watch area is approximately along and 50 statute miles north and south of a line from 10 miles northwest of La Grange GA to 15 miles south of Augusta GA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU6). 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 595... AVIATION...A few severe thunderstorms with hail surface and aloft to 0.5 inches. Extreme turbulence and surface wind gusts to 55 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 28020. ...Guyer Read more

WW 0595 Status Updates
STATUS REPORT ON WW 595 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 15 SSE TCL TO 10 SW GAD TO 35 W RMG TO 20 NW CHA. ..LYONS..08/06/23 ATTN...WFO...BMX...HUN...OHX... STATUS REPORT FOR WS 595 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ALC015-019-027-029-055-111-115-117-121-062240- AL . ALABAMA COUNTIES INCLUDED ARE CALHOUN CHEROKEE CLAY CLEBURNE ETOWAH RANDOLPH ST. CLAIR SHELBY TALLADEGA THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 595 SEVERE TSTM AL TN 061820Z - 070100Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 595 NWS Storm Prediction Center Norman OK 120 PM CDT Sun Aug 6 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northern Alabama Middle Tennessee * Effective this Sunday afternoon and evening from 120 PM until 800 PM CDT. * Primary threats include... Scattered damaging wind gusts to 65 mph possible SUMMARY...A cluster of storms will likely evolve and move generally eastward across the region this afternoon, with damaging winds as the most common severe-weather hazard. The severe thunderstorm watch area is approximately along and 80 statute miles north and south of a line from 40 miles southwest of Muscle Shoals AL to 45 miles northeast of Gadsden AL. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU5). 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 550. Mean storm motion vector 27020. ...Guyer Read more

MD 1868 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR CENTRAL COLORADO
Mesoscale Discussion 1868 NWS Storm Prediction Center Norman OK 0425 PM CDT Sun Aug 06 2023 Areas affected...Central Colorado Concerning...Severe potential...Watch unlikely Valid 062125Z - 062330Z Probability of Watch Issuance...20 percent SUMMARY...An isolated severe wind/hail threat may materialize across central Colorado if developing thunderstorms can become established. Confidence in this scenario is uncertain, and the threat is expected to remain sufficiently isolated to negate the need for a watch. However, trends will be monitored given the strong environmental shear. DISCUSSION...Early attempts at supercell development within an upslope flow regime are underway across the front range of central CO per recent KFTG imagery. Lift away from the terrain is rather meager, and a stout cap was sampled by recent ACAR soundings out of Denver, CO. While lift and thermodynamic conditions are not overly favorable for supercell sustenance away from the terrain, environmental wind shear is very favorable for organized convection. The same ACAR soundings sampled elongated, straight hodographs featuring deep-layer shear on the order of 50-60 knots. This wind profile favors storm splitting, which has already been observed with a few early (though transient) cells. Additionally, a mid-level baroclinic zone is noted in 700 mb analyses draped from central to southeast CO. This may be a preferential corridor for supercell propagation if shear-related pressure perturbations can compensate for the modest thermodynamic environment and allow storm maturation. If this occurs, supercells will be capable of very large hail and severe winds. Confidence in the manifestation of this threat, as well as the spatial coverage of storms, remains uncertain and currently precludes watch issuance, but trends will continue to be monitored. ..Moore/Edwards.. 08/06/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GLD...PUB...BOU... LAT...LON 38890511 39150542 39480555 39850548 40040533 40150499 40110474 39270317 39020290 38680265 38370263 38050270 37850299 37800335 38890511 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Sun Aug 06 2023 Valid 062000Z - 071200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDDLE MISSISSIPPI/LOWER OHIO VALLEYS AND MID-SOUTH/SOUTHEAST...AND EAST-CENTRAL COLORADO... ...SUMMARY... A few tornadoes along with scattered damaging winds and large hail will be possible from late afternoon into tonight from the Mid-Mississippi to Lower Ohio Valleys. Scattered damaging winds will also be possible, mainly this afternoon into early evening across parts of the Mid-South and Southeast. ...Discussion... The only change this outlook update is to increase severe hail probabilities (categorical risk from Marginal Risk to Slight Risk) from the Palmer Divide east-southeastward into southeast CO for a supercell hail risk this evening into the late night hours. Recent time-lagged HRRR runs and HREF probabilities show storms developing over the Palmer Divide and moving east-southeast with a favorable buoyancy/shear profile for hail growth. The HREF but not HRRR also showed intense storms developing near the Raton Mesa but confidence in this scenario is a little lower (hence maintaining a Marginal Risk for the time being). ..Smith.. 08/06/2023 .PREV DISCUSSION... /ISSUED 1144 AM CDT Sun Aug 06 2023/ ...Middle Mississippi/Lower Ohio Valleys... Multiple eastward-moving/decaying MCVs are still evident across the region ahead of the primary synoptic cyclone across Iowa. Ahead of this cyclone, a moisture-rich warm sector will expand north-northeastward across downstate portions of Illinois/Indiana this afternoon into tonight in tandem with a warm front. An arc of initially semi-discrete thunderstorms are expected to develop within the somewhat narrow warm sector by mid/late-afternoon, initially across southeast Iowa/far eastern Missouri and west-central/southwest Illinois. Seasonally strong winds through a deep-layer will support supercellular development, with low-level shear/SRH expected to be maximized particularly across southern Illinois 1) in vicinity of the warm front and 2) toward/after sunset as winds within the lowest 1-3 km AGL increase. A few tornadoes are possible regionally, including supercell-related potential for large hail mainly within the first couple of hours of deep convective development. Into late evening, upscale growth into one or two organized clusters is plausible, with the potential for an MCS to evolve along the northern extent of the surface-based instability plume. An elongated swath or two of damaging winds with embedded severe gusts, along with a couple brief tornadoes may be sustained into the early overnight into the Lower Ohio Valley. ...Mid-South/Southeast States... The boundary layer across the region continues to steadily warm/destabilize. A decaying MCS/MCV across Arkansas at midday appears to already being influencing subsequent thunderstorm development downstream across northern Mississippi, while additional storms continue near the southern Appalachians. 25-35 kt 700-mb westerlies across the Tennessee Valley should be adequate to support semi-organized multicell clusters amid an extensive plume of large buoyancy across the Deep South. Scattered damaging wind swaths from water-loaded downbursts will be possible through early evening. Later tonight, strengthening low-level warm theta-e advection focused along residual outflow/effective baroclinic zone over the Mid-South could influence additional strong thunderstorm development. This activity could pose an isolated threat for severe hail initially before potentially clustering into a localized damaging wind threat overnight. ...Central/southern Rockies and Front Range... The presence of 50s F surface dew points will support potential for isolated but regenerative thunderstorms to develop along the Front Range during the late afternoon and evening. A rather confined corridor for weak buoyancy with MLCAPE of only 500-1000 J/kg should be maximized near the Front Range. Deep-layer wind profiles will be quite favorable for supercells and large hail potential given near-perfectly straight-line hodographs. Downstream of a minor shortwave trough over the interior Northwest, isolated to scattered afternoon thunderstorms are anticipated around the UT/WY/CO border area within a weak buoyancy plume. Adequate deep-layer shear will exist for a threat of marginally severe hail and wind centered on the late afternoon. ...Central/southern Appalachians to Lake Erie... Multiple MCVs are expected to aid scattered intensifying thunderstorm development downstream of these features this afternoon. Pockets of modestly stronger low to mid-level flow attendant to these MCVs may support sporadic localized damaging winds, and perhaps even some funnel/brief tornado potential in vicinity of Lake Erie near a weak surface low/warm front. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0239 PM CDT Sun Aug 06 2023 Valid 071200Z - 081200Z The Elevated risk across southwestern Texas was expanded into central Texas/Texas Hill Country. Winds will be marginal (sustained at 10-15 mph) but recent fire activity in this region has been increasing with extremely critical fuels and very hot/unstable conditions. This, in combination with afternoon relative humidity reductions to 15-20 percent, support inclusion of the region into an Elevated risk. Otherwise, the Southwest Elevated remains on track with no further updates needed. See previous discussion for more information. ..Thornton.. 08/06/2023 .PREV DISCUSSION... /ISSUED 0137 AM CDT Sun Aug 06 2023/ ...Synopsis... Fire weather concerns will once again be focused across the greater Four Corners region on Monday with more regional potential across parts of southwest Texas. ...Four Corners... Moderate mid-level flow is expected to persist across the greater Four Corners region on Monday. The deepening of a modest lee trough along the High Plains will increase the probability of 15-20 mph winds, and deep boundary-layer mixing will foster gusts up to 30-35 mph. RH values in the low teens will be common, and may fall as low as the single digits. Consequently, critical wind/RH conditions are possible, but confidence in the coverage/duration of such conditions is uncertain given a lack of more prominent upper-level or surface features. Additionally, some question remains regarding the southern extent of the threat due to the potential for isolated showers/thunderstorms across AZ and western NM. Regardless, widespread elevated conditions appear likely. ...Southwest Texas... The regional pressure gradient is expected to strengthen slightly through the day across southwest TX as a modest lee surface trough develops across the southern High Plains under zonal flow aloft. This will boost the potential for sustained 15 mph winds across the region. While not overly strong, they should be sufficient to support a regional fire weather concern given antecedent critically dry fuels, forecast temperatures exceeding 100 F, and RH values falling into the low 20s. The weak nature of the surface trough and associated mass response casts uncertainty onto the coverage/duration of this threat, but ensemble guidance hints at sufficient potential to warrant Elevated highlights. ...Nevada... The zonal flow regime over the Great Basin/Four Corners will likely result in dry downslope flow off the northern Sierra Nevada Monday afternoon. This could result in areas of elevated fire weather conditions across western NV, and possibly as far east as central NV. Confidence in the coverage and overlap of elevated conditions with receptive fuels is uncertain away from the immediate lee of the terrain, but trends will be monitored for additional highlights. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1243 PM CDT Sun Aug 06 2023 Valid 071200Z - 081200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR THE MID-ATLANTIC STATES INTO THE SOUTHERN APPALACHIANS AND CAROLINAS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Severe thunderstorms are possible Monday across portions of the southern Appalachians, mid-Atlantic and northeast U.S. Scattered swaths of damaging gusts are expected with this activity. Additional widely scattered thunderstorms are possible across the central High Plains, posing a risk for large hail and severe gusts. ...Synopsis... A potent mid/upper shortwave trough will move from IL to the central Appalachians during the period. A seasonally anomalous belt of strong west/southwesterly flow will move through the base of the trough and overspread the central/southern Appalachians into the Mid-Atlantic states. In the low levels, low pressure will develop east from northern IL to Lake Erie through evening. A cold front attendant to the surface low will sweep east/southeast across the Midwest during the day and reach the Appalachians and northern MS/AL late overnight. ...OH Valley to Mid-Atlantic to the southern Appalachians and Carolinas... Scattered showers and isolated storms are forecast to be ongoing over the OH Valley Monday morning with more widely spaced convection trailing west-southwest into the Mid South/Ozarks. Considerable cloud cover with northward extent over a large moist/warm sector will limit destabilization into portions of PA and north. Farther south, heating of a very moist boundary layer will yield a moderate to very unstable airmass (1500 to 3000+ J/kg MLCAPE) from PA southward into the southern Appalachians. Multiple bands and clusters will likely begin to develop towards midday over the upper OH Valley and central Appalachians. Less certain is convective timing over the TN Valley where a large spread of model solutions is currently depicted. Nonetheless, scattered thunderstorms will likely develop by early to mid afternoon and become quite extensive from northern AL/GA into PA/VA/WV/MD. A mix of semi-discrete cells and clusters are possible initially and a risk for all severe hazards is expected given favorable shear profiles for storm organization/low-level rotation. Upscale growth is expected as storms move into the northern VA/MD and Chesapeake Bay vicinity during the late afternoon/early evening where the wind risk will seemingly be maximized. Much of the activity will eventually move east of the Mid-Atlantic coast during the evening and areas farther south through the Carolina Piedmont and into the coastal plain. ...Central into the southern High Plains... Moderate mid/upper northwesterly flow will continue to stream across the central High Plains vicinity on Monday. Moderately cool 500 mb temps around -10 C will support steep midlevel lapse rates. Modest boundary layer moisture is forecast along a surface trough, with dewpoints generally in the 50s, supporting moderate instability. Strong vertical shear (effective shear greater than 45 kt) will foster organized updrafts, while elongated/straight hodographs suggest large hail will be possible and perhaps a narrow window for very large hail with initial supercells. A deeply-mixed boundary-layer with dewpoint depressions around 20 F also may foster strong gust potential. The latest models show some of this activity continuing into west-central KS after dark. Farther south, models are suggesting thunderstorms will develop on the southern fringe of stronger westerlies near the eastern NM/TX South Plains vicinity. Deep, well-mixed boundary-layer profiles will potentially support isolated severe gusts during the early evening. ...Northeast TX toward the Lower MS Valley... A surface boundary is forecast to extend west to east across the region. Differential heating along the boundary, and a very moist/unstable airmass will support isolated thunderstorm development. Vertical shear will be rather weak, but isolated strong gusts may accompany thunderstorms during the afternoon. Isolated coverage/longevity of this activity preclude higher risk probabilities. ..Smith.. 08/06/2023 Read more

MD 1849 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR WESTERN KS
Mesoscale Discussion 1849 NWS Storm Prediction Center Norman OK 0522 PM CDT Sat Aug 05 2023 Areas affected...Western KS Concerning...Severe potential...Watch possible Valid 052222Z - 052345Z Probability of Watch Issuance...60 percent SUMMARY...Strong/severe thunderstorms will spread/develop east across CO into western KS this evening. Hail/wind are the primary threats. DISCUSSION...Central High Plains short-wave trough currently extends across the NE Panhandle into eastern CO. Thunderstorms have been gradually increasing ahead of this feature within a corridor of seasonally strong buoyancy, especially from Yuma to Pueblo County Colorado. Latest satellite imagery suggests an agitated cu field within the boundary layer across northwestern KS with several deepening towers over Gove/Trego County region. 35-50kt 500mb flow across CO into KS favors eastward propagation over the next few hours. Given the air mass currently observed over the central High Plains, new severe thunderstorm watch appears warranted. ..Darrow/Mosier.. 08/05/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DDC...GLD... LAT...LON 37370200 39780175 39499969 37210049 37370200 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0459 PM CDT Sat Aug 05 2023 Valid 071200Z - 131200Z ...Southwest... Dry westerly flow across the northern Arizona and north/central New Mexico will continue to augment drying fuels on D3 - Monday and D4 - Tuesday. Moisture will attempt to move into far southern/south-central New Mexico Monday into Tuesday, which will limit the southward extent of lower relative humidity. The mid-level high will begin to build back in across the Four Corners Region from Tuesday onward, with decreasing wind and increasing temperatures. Pockets of Elevated fire weather concerns will be possible with afternoon relative humidity around 15-20 percent but breezes will be localized and remain below Critical criteria. A return of more appreciable monsoon moisture further north into northern Arizona/western New Mexico looks favorable by late in the period as the high builds with weak troughing off the west coast enhancing southerly moisture transport off the Gulf of California. ...Central Texas... Extremely hot and dry conditions continue to render extremely dry fuels across central/southwestern Texas. Elevated conditions are possible most each day of the extended period, with the limiting factor being widespread sustained winds at or above 15 mph. Even in the absence of winds, fuels and extremely hot and unstable conditions continue to foster increased fire behavior. A surface front sagging southward Sunday into early Monday will cool highs and bring increase in cloud cover and shower/thunderstorm potential across northern Texas near the Red River Valley. Mainly light rainfall is forecast within this region, which may not change the status of fuels considerably heading into increasing winds on Tuesday/Wednesday as a surface low develops across the Southern Plains. Afternoon relative humidity reductions to 15-20 percent and sustained winds 15-20 mph will be possible on Tuesday and Wednesday. 40 percent probabilities were introduced on these days with better confidence in the stronger winds overlapping continued hot/dry conditions. ..Thornton.. 08/05/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 1848 CONCERNING TORNADO WATCH 589... FOR NORTHWESTERN IOWA INTO ADJACENT AREAS OF SOUTH DAKOTA AND NEBRASKA
Mesoscale Discussion 1848 NWS Storm Prediction Center Norman OK 0502 PM CDT Sat Aug 05 2023 Areas affected...Northwestern Iowa into adjacent areas of South Dakota and Nebraska Concerning...Tornado Watch 589... Valid 052202Z - 060000Z The severe weather threat for Tornado Watch 589 continues. SUMMARY...The threat for a tornado or two continues across northwestern Iowa into adjacent areas of southeast South Dakota and northwest Nebraska. DISCUSSION...Thunderstorm activity over the mid-Missouri River Valley continues to be focused along a surface warm front noted in recent surface analysis. By most metrics, this convective intensity has been muted with modest reflectivity values, transient lightning pulses, and somewhat warm cloud top temperatures. However, cells continue to take on supercellular characteristics early on in their life cycle, and weak low to mid-level rotation is noted in KFSD velocity data. KFSD VWP observations well north of the warm front show 0-1 km SRH values near 200 m2/s2 where surface winds are easterly. This is likely an overestimate for the what cells are experiencing along the warm front (where winds are out of the southeast). But taken in context of the velocity trends suggests that SRH is likely sufficient to maintain a tornado threat for more robust cells that can become established prior to moving into a more stable air mass north/northeast of the warm front. ..Moore.. 08/05/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DMX...FSD...OAX... LAT...LON 41489551 41949588 42389633 42729702 43049721 43339697 43289606 42879521 42589469 42119433 41599426 41289444 41189467 41159502 41239529 41489551 Read more

WW 0592 Status Updates
STATUS REPORT ON WW 592 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..LYONS..08/05/23 ATTN...WFO...ILX...IND... STATUS REPORT FOR WT 592 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC023-033-079-101-159-052340- IL . ILLINOIS COUNTIES INCLUDED ARE CLARK CRAWFORD JASPER LAWRENCE RICHLAND INC005-011-013-015-021-023-027-031-035-045-055-057-059-063-065- 067-071-079-081-083-093-095-097-101-105-107-109-119-121-133-139- 145-153-157-159-165-167-171-052340- IN . INDIANA COUNTIES INCLUDED ARE BARTHOLOMEW BOONE BROWN CARROLL CLAY CLINTON DAVIESS DECATUR DELAWARE FOUNTAIN GREENE HAMILTON HANCOCK HENDRICKS HENRY HOWARD JACKSON JENNINGS JOHNSON KNOX LAWRENCE MADISON MARION MARTIN MONROE MONTGOMERY MORGAN OWEN PARKE PUTNAM Read more