Aggregator

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1113 AM CDT Sun Aug 18 2019 Valid 181700Z - 191200Z No changes. See previous discussion below. ..Bentley.. 08/18/2019 .PREV DISCUSSION... /ISSUED 0116 AM CDT Sun Aug 18 2019/ ...Synopsis... Upper-level ridging will amplify over the western CONUS as an upper-level shortwave trough moves over the northern Plains and Great Lakes. Mid-level 25-50 knot westerly flow will remain over the northern Intermountain West with hot/dry conditions across much of the Intermountain West. Elevated conditions (westerly sustained surface winds of 15-20 mph, RH values of 10-20%) will develop from southern Idaho into southern/central Wyoming and northwest Colorado/northeast Utah this afternoon/evening. This is the fourth consecutive day of dry/windy conditions across this area, which will continue to cure fuels with ERCs now mostly in the 70-90th percentiles. Locally elevated conditions (southerly winds of 10-20 mph, RH values of 8-15%) are likely to develop this afternoon/evening across northwest Arizona into southeast Nevada/southwest Utah. While these conditions are relatively common for this area and time of year, dry fuels and ongoing fire activity in the area warranted a mention. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1113 AM CDT Sun Aug 18 2019 Valid 181700Z - 191200Z No changes. See previous discussion below. ..Bentley.. 08/18/2019 .PREV DISCUSSION... /ISSUED 0116 AM CDT Sun Aug 18 2019/ ...Synopsis... Upper-level ridging will amplify over the western CONUS as an upper-level shortwave trough moves over the northern Plains and Great Lakes. Mid-level 25-50 knot westerly flow will remain over the northern Intermountain West with hot/dry conditions across much of the Intermountain West. Elevated conditions (westerly sustained surface winds of 15-20 mph, RH values of 10-20%) will develop from southern Idaho into southern/central Wyoming and northwest Colorado/northeast Utah this afternoon/evening. This is the fourth consecutive day of dry/windy conditions across this area, which will continue to cure fuels with ERCs now mostly in the 70-90th percentiles. Locally elevated conditions (southerly winds of 10-20 mph, RH values of 8-15%) are likely to develop this afternoon/evening across northwest Arizona into southeast Nevada/southwest Utah. While these conditions are relatively common for this area and time of year, dry fuels and ongoing fire activity in the area warranted a mention. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1113 AM CDT Sun Aug 18 2019 Valid 181700Z - 191200Z No changes. See previous discussion below. ..Bentley.. 08/18/2019 .PREV DISCUSSION... /ISSUED 0116 AM CDT Sun Aug 18 2019/ ...Synopsis... Upper-level ridging will amplify over the western CONUS as an upper-level shortwave trough moves over the northern Plains and Great Lakes. Mid-level 25-50 knot westerly flow will remain over the northern Intermountain West with hot/dry conditions across much of the Intermountain West. Elevated conditions (westerly sustained surface winds of 15-20 mph, RH values of 10-20%) will develop from southern Idaho into southern/central Wyoming and northwest Colorado/northeast Utah this afternoon/evening. This is the fourth consecutive day of dry/windy conditions across this area, which will continue to cure fuels with ERCs now mostly in the 70-90th percentiles. Locally elevated conditions (southerly winds of 10-20 mph, RH values of 8-15%) are likely to develop this afternoon/evening across northwest Arizona into southeast Nevada/southwest Utah. While these conditions are relatively common for this area and time of year, dry fuels and ongoing fire activity in the area warranted a mention. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1113 AM CDT Sun Aug 18 2019 Valid 181700Z - 191200Z No changes. See previous discussion below. ..Bentley.. 08/18/2019 .PREV DISCUSSION... /ISSUED 0116 AM CDT Sun Aug 18 2019/ ...Synopsis... Upper-level ridging will amplify over the western CONUS as an upper-level shortwave trough moves over the northern Plains and Great Lakes. Mid-level 25-50 knot westerly flow will remain over the northern Intermountain West with hot/dry conditions across much of the Intermountain West. Elevated conditions (westerly sustained surface winds of 15-20 mph, RH values of 10-20%) will develop from southern Idaho into southern/central Wyoming and northwest Colorado/northeast Utah this afternoon/evening. This is the fourth consecutive day of dry/windy conditions across this area, which will continue to cure fuels with ERCs now mostly in the 70-90th percentiles. Locally elevated conditions (southerly winds of 10-20 mph, RH values of 8-15%) are likely to develop this afternoon/evening across northwest Arizona into southeast Nevada/southwest Utah. While these conditions are relatively common for this area and time of year, dry fuels and ongoing fire activity in the area warranted a mention. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1113 AM CDT Sun Aug 18 2019 Valid 181700Z - 191200Z No changes. See previous discussion below. ..Bentley.. 08/18/2019 .PREV DISCUSSION... /ISSUED 0116 AM CDT Sun Aug 18 2019/ ...Synopsis... Upper-level ridging will amplify over the western CONUS as an upper-level shortwave trough moves over the northern Plains and Great Lakes. Mid-level 25-50 knot westerly flow will remain over the northern Intermountain West with hot/dry conditions across much of the Intermountain West. Elevated conditions (westerly sustained surface winds of 15-20 mph, RH values of 10-20%) will develop from southern Idaho into southern/central Wyoming and northwest Colorado/northeast Utah this afternoon/evening. This is the fourth consecutive day of dry/windy conditions across this area, which will continue to cure fuels with ERCs now mostly in the 70-90th percentiles. Locally elevated conditions (southerly winds of 10-20 mph, RH values of 8-15%) are likely to develop this afternoon/evening across northwest Arizona into southeast Nevada/southwest Utah. While these conditions are relatively common for this area and time of year, dry fuels and ongoing fire activity in the area warranted a mention. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No Mesoscale Discussions are in effect as of Sun Aug 18 16:16:02 UTC 2019.

WW 0597 Status Updates
STATUS REPORT ON WW 597 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 45 NE LAF TO 20 SW AZO TO 25 ENE GRR TO 50 NNE GRR. ..LEITMAN..08/18/19 ATTN...WFO...DVN...LOT...IWX...GRR...MKX... STATUS REPORT FOR WS 597 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS INC039-085-087-113-151-183-181740- IN . INDIANA COUNTIES INCLUDED ARE ELKHART KOSCIUSKO LAGRANGE NOBLE STEUBEN WHITLEY MIC023-025-037-045-057-065-075-149-181740- MI . MICHIGAN COUNTIES INCLUDED ARE BRANCH CALHOUN CLINTON EATON GRATIOT INGHAM JACKSON ST. JOSEPH 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 0597 Status Updates
STATUS REPORT ON WW 597 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 45 NE LAF TO 20 SW AZO TO 25 ENE GRR TO 50 NNE GRR. ..LEITMAN..08/18/19 ATTN...WFO...DVN...LOT...IWX...GRR...MKX... STATUS REPORT FOR WS 597 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS INC039-085-087-113-151-183-181740- IN . INDIANA COUNTIES INCLUDED ARE ELKHART KOSCIUSKO LAGRANGE NOBLE STEUBEN WHITLEY MIC023-025-037-045-057-065-075-149-181740- MI . MICHIGAN COUNTIES INCLUDED ARE BRANCH CALHOUN CLINTON EATON GRATIOT INGHAM JACKSON ST. JOSEPH 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 0597 Status Updates
STATUS REPORT ON WW 597 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 45 NE LAF TO 20 SW AZO TO 25 ENE GRR TO 50 NNE GRR. ..LEITMAN..08/18/19 ATTN...WFO...DVN...LOT...IWX...GRR...MKX... STATUS REPORT FOR WS 597 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS INC039-085-087-113-151-183-181740- IN . INDIANA COUNTIES INCLUDED ARE ELKHART KOSCIUSKO LAGRANGE NOBLE STEUBEN WHITLEY MIC023-025-037-045-057-065-075-149-181740- MI . MICHIGAN COUNTIES INCLUDED ARE BRANCH CALHOUN CLINTON EATON GRATIOT INGHAM JACKSON ST. JOSEPH 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 0597 Status Updates
STATUS REPORT ON WW 597 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 45 NE LAF TO 20 SW AZO TO 25 ENE GRR TO 50 NNE GRR. ..LEITMAN..08/18/19 ATTN...WFO...DVN...LOT...IWX...GRR...MKX... STATUS REPORT FOR WS 597 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS INC039-085-087-113-151-183-181740- IN . INDIANA COUNTIES INCLUDED ARE ELKHART KOSCIUSKO LAGRANGE NOBLE STEUBEN WHITLEY MIC023-025-037-045-057-065-075-149-181740- MI . MICHIGAN COUNTIES INCLUDED ARE BRANCH CALHOUN CLINTON EATON GRATIOT INGHAM JACKSON ST. JOSEPH 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 597 SEVERE TSTM IA IL IN MI WI LM 181105Z - 181800Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 597 NWS Storm Prediction Center Norman OK 605 AM CDT Sun Aug 18 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Extreme eastern Iowa Northern Illinois Northern Indiana Southwestern and south-central Lower Michigan Southern Wisconsin Lake Michigan * Effective this Sunday morning and afternoon from 605 AM until 100 PM CDT. * Primary threats include... Scattered 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...An increasingly organized band of thunderstorms should continue to strengthen through the remainder of the morning as it encounters a favorably moist and destabilizing air mass across the watch area. As this occurs, the threat for damaging wind should become more dense and intense, and isolated risk for a QLCS tornado may appear as well. See SPC mesoscale discussion 1785 for initial meteorological reasoning. The severe thunderstorm watch area is approximately along and 135 statute miles east and west of a line from 45 miles southeast of Marseilles IL to 40 miles east northeast of Milwaukee WI. 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 596... 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 27040. ...Edwards Read more

WW 0597 Status Updates
STATUS REPORT ON WW 597 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 30 NE BMI TO 30 NE MMO TO 50 NNE MMO TO 45 SSW RAC TO 15 ESE RAC TO 40 SSE MTW. ..ELLIOTT..08/18/19 ATTN...WFO...DVN...LOT...IWX...GRR...MKX... STATUS REPORT FOR WS 597 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC031-043-091-197-181540- IL . ILLINOIS COUNTIES INCLUDED ARE COOK DUPAGE KANKAKEE WILL INC039-049-073-085-087-089-091-099-111-113-127-131-141-149-151- 183-181540- IN . INDIANA COUNTIES INCLUDED ARE ELKHART FULTON JASPER KOSCIUSKO LAGRANGE LAKE LA PORTE MARSHALL NEWTON NOBLE PORTER PULASKI ST. JOSEPH STARKE STEUBEN WHITLEY MIC005-015-021-023-025-027-037-045-057-065-067-075-077-081-117- 121-139-149-159-181540- Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0756 AM CDT Sun Aug 18 2019 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE SOUTHERN UPPER GREAT LAKES AND VICINITY... ...SUMMARY... The main severe-thunderstorm threat today will be damaging winds, isolated hail and a few tornadoes are possible. ...Synopsis... In mid/upper levels, a belt of zonal to gently cyclonic mean flow will be observed through the period across the northern half of the CONUS. As a cyclone moves slowly northeastward across northern MB, the trailing shortwave trough should pivot from the Dakotas across MN and Lake Superior to northeastern ON. As that occurs, convectively aided/induced vorticity lobes should move eastward across the upper Great Lakes. This includes a shortwave perturbation associated with a pronounced MCV now located over southern WI, and extending south-southwestward behind a band of convection across southern WI and northwestern IL. The 11Z surface chart showed a low near EAU, related to the MCV, with wavy warm front extending across western/southern WI and southern Lower MI. This front should drift northward before being overtaken by an ongoing MCS and additional convection developing farther east. A cold front was drawn from southeastern MN across southeastern NE and northwestern KS. By 00Z this front should reach eastern Upper MI, central WI, southern IA, central/southwestern KS, and southeastern CO. By 12Z this front should extend from northern Lower MI to northern IL, central/western MO, northwestern OK, becoming quasistationary northwestward into southeastern CO. ...Great Lakes vicinity... An intermittently organized band of convection, continuing eastward from overnight activity across IA, has persisted across the Mississippi River the past couple hours. Some of this activity may strengthen across the remainder of the northern IL/southern WI/Lake Michigan region eastward over northern IN and southern lower MI, as the foregoing/inflow-layer air mass destabilizes from a combination of warm advection and diabatic surface heating. Recovery behind newer convection over northeastern IL is uncertain in magnitude and northern extent. See SPC severe thunderstorm watch 597 and related mesoscale discussions for near-term details. In concert with seasonally steep low/middle-level lapse rates and rich low-level moisture (60s to near 70 F surface dew points), areas of 2000-3000 J/kg preconvective MLCAPE are expected to develop. This will occur amidst difluent but generally westerly mid/upper winds, enhanced on the mesoscale by height falls related to the MCV, and a plume of large-scale DCVA/lift preceding the shortwave trough. As the heating continues, MLCINH effectively will vanish over northeastern IL and eastward through midday, potentially fostering additional convective development and severe potential in and near the watch area, regardless of the morphology of the initial MCS. Subsequent aggregation and upscale growth should shift the primary threat of damaging winds across lower MI and northern IN. In addition, areas of relatively maximized effective SRH may support localized tornado potential in QLCS circulations. ...Ozarks to portions of OK... Isolated to scattered thunderstorms, with highly variable coverage in space and time, are possible through the overnight period across this region. Activity should be concentrated mainly near outflow/ differential-heating boundaries area-wide and near a weak convergence zone over the southwestern OK/northwest TX region this afternoon. Isolated severe gusts and hail may occur, with well- mixed air below LFC developing this afternoon, and persisting into tonight above a slowly stabilizing near-surface layer, aiding in maintenance of hail/gusts to surface. A relative concentration in severe potential also may become apparent this afternoon over portions of this region, especially in the Ozarks/eastern OK/southeastern KS area. Beneath steep midlevel lapse rates, pockets of relatively convectively undisturbed boundary-layer moisture and strong heating may support MLCAPE around 4000 J/kg. Uncertainties regarding location, orientation, and strength of supportive mesoscale boundaries preclude a more- concentrated area of unconditional probabilities at this time. ..Edwards/Marsh.. 08/18/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0756 AM CDT Sun Aug 18 2019 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE SOUTHERN UPPER GREAT LAKES AND VICINITY... ...SUMMARY... The main severe-thunderstorm threat today will be damaging winds, isolated hail and a few tornadoes are possible. ...Synopsis... In mid/upper levels, a belt of zonal to gently cyclonic mean flow will be observed through the period across the northern half of the CONUS. As a cyclone moves slowly northeastward across northern MB, the trailing shortwave trough should pivot from the Dakotas across MN and Lake Superior to northeastern ON. As that occurs, convectively aided/induced vorticity lobes should move eastward across the upper Great Lakes. This includes a shortwave perturbation associated with a pronounced MCV now located over southern WI, and extending south-southwestward behind a band of convection across southern WI and northwestern IL. The 11Z surface chart showed a low near EAU, related to the MCV, with wavy warm front extending across western/southern WI and southern Lower MI. This front should drift northward before being overtaken by an ongoing MCS and additional convection developing farther east. A cold front was drawn from southeastern MN across southeastern NE and northwestern KS. By 00Z this front should reach eastern Upper MI, central WI, southern IA, central/southwestern KS, and southeastern CO. By 12Z this front should extend from northern Lower MI to northern IL, central/western MO, northwestern OK, becoming quasistationary northwestward into southeastern CO. ...Great Lakes vicinity... An intermittently organized band of convection, continuing eastward from overnight activity across IA, has persisted across the Mississippi River the past couple hours. Some of this activity may strengthen across the remainder of the northern IL/southern WI/Lake Michigan region eastward over northern IN and southern lower MI, as the foregoing/inflow-layer air mass destabilizes from a combination of warm advection and diabatic surface heating. Recovery behind newer convection over northeastern IL is uncertain in magnitude and northern extent. See SPC severe thunderstorm watch 597 and related mesoscale discussions for near-term details. In concert with seasonally steep low/middle-level lapse rates and rich low-level moisture (60s to near 70 F surface dew points), areas of 2000-3000 J/kg preconvective MLCAPE are expected to develop. This will occur amidst difluent but generally westerly mid/upper winds, enhanced on the mesoscale by height falls related to the MCV, and a plume of large-scale DCVA/lift preceding the shortwave trough. As the heating continues, MLCINH effectively will vanish over northeastern IL and eastward through midday, potentially fostering additional convective development and severe potential in and near the watch area, regardless of the morphology of the initial MCS. Subsequent aggregation and upscale growth should shift the primary threat of damaging winds across lower MI and northern IN. In addition, areas of relatively maximized effective SRH may support localized tornado potential in QLCS circulations. ...Ozarks to portions of OK... Isolated to scattered thunderstorms, with highly variable coverage in space and time, are possible through the overnight period across this region. Activity should be concentrated mainly near outflow/ differential-heating boundaries area-wide and near a weak convergence zone over the southwestern OK/northwest TX region this afternoon. Isolated severe gusts and hail may occur, with well- mixed air below LFC developing this afternoon, and persisting into tonight above a slowly stabilizing near-surface layer, aiding in maintenance of hail/gusts to surface. A relative concentration in severe potential also may become apparent this afternoon over portions of this region, especially in the Ozarks/eastern OK/southeastern KS area. Beneath steep midlevel lapse rates, pockets of relatively convectively undisturbed boundary-layer moisture and strong heating may support MLCAPE around 4000 J/kg. Uncertainties regarding location, orientation, and strength of supportive mesoscale boundaries preclude a more- concentrated area of unconditional probabilities at this time. ..Edwards/Marsh.. 08/18/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0756 AM CDT Sun Aug 18 2019 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE SOUTHERN UPPER GREAT LAKES AND VICINITY... ...SUMMARY... The main severe-thunderstorm threat today will be damaging winds, isolated hail and a few tornadoes are possible. ...Synopsis... In mid/upper levels, a belt of zonal to gently cyclonic mean flow will be observed through the period across the northern half of the CONUS. As a cyclone moves slowly northeastward across northern MB, the trailing shortwave trough should pivot from the Dakotas across MN and Lake Superior to northeastern ON. As that occurs, convectively aided/induced vorticity lobes should move eastward across the upper Great Lakes. This includes a shortwave perturbation associated with a pronounced MCV now located over southern WI, and extending south-southwestward behind a band of convection across southern WI and northwestern IL. The 11Z surface chart showed a low near EAU, related to the MCV, with wavy warm front extending across western/southern WI and southern Lower MI. This front should drift northward before being overtaken by an ongoing MCS and additional convection developing farther east. A cold front was drawn from southeastern MN across southeastern NE and northwestern KS. By 00Z this front should reach eastern Upper MI, central WI, southern IA, central/southwestern KS, and southeastern CO. By 12Z this front should extend from northern Lower MI to northern IL, central/western MO, northwestern OK, becoming quasistationary northwestward into southeastern CO. ...Great Lakes vicinity... An intermittently organized band of convection, continuing eastward from overnight activity across IA, has persisted across the Mississippi River the past couple hours. Some of this activity may strengthen across the remainder of the northern IL/southern WI/Lake Michigan region eastward over northern IN and southern lower MI, as the foregoing/inflow-layer air mass destabilizes from a combination of warm advection and diabatic surface heating. Recovery behind newer convection over northeastern IL is uncertain in magnitude and northern extent. See SPC severe thunderstorm watch 597 and related mesoscale discussions for near-term details. In concert with seasonally steep low/middle-level lapse rates and rich low-level moisture (60s to near 70 F surface dew points), areas of 2000-3000 J/kg preconvective MLCAPE are expected to develop. This will occur amidst difluent but generally westerly mid/upper winds, enhanced on the mesoscale by height falls related to the MCV, and a plume of large-scale DCVA/lift preceding the shortwave trough. As the heating continues, MLCINH effectively will vanish over northeastern IL and eastward through midday, potentially fostering additional convective development and severe potential in and near the watch area, regardless of the morphology of the initial MCS. Subsequent aggregation and upscale growth should shift the primary threat of damaging winds across lower MI and northern IN. In addition, areas of relatively maximized effective SRH may support localized tornado potential in QLCS circulations. ...Ozarks to portions of OK... Isolated to scattered thunderstorms, with highly variable coverage in space and time, are possible through the overnight period across this region. Activity should be concentrated mainly near outflow/ differential-heating boundaries area-wide and near a weak convergence zone over the southwestern OK/northwest TX region this afternoon. Isolated severe gusts and hail may occur, with well- mixed air below LFC developing this afternoon, and persisting into tonight above a slowly stabilizing near-surface layer, aiding in maintenance of hail/gusts to surface. A relative concentration in severe potential also may become apparent this afternoon over portions of this region, especially in the Ozarks/eastern OK/southeastern KS area. Beneath steep midlevel lapse rates, pockets of relatively convectively undisturbed boundary-layer moisture and strong heating may support MLCAPE around 4000 J/kg. Uncertainties regarding location, orientation, and strength of supportive mesoscale boundaries preclude a more- concentrated area of unconditional probabilities at this time. ..Edwards/Marsh.. 08/18/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0756 AM CDT Sun Aug 18 2019 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE SOUTHERN UPPER GREAT LAKES AND VICINITY... ...SUMMARY... The main severe-thunderstorm threat today will be damaging winds, isolated hail and a few tornadoes are possible. ...Synopsis... In mid/upper levels, a belt of zonal to gently cyclonic mean flow will be observed through the period across the northern half of the CONUS. As a cyclone moves slowly northeastward across northern MB, the trailing shortwave trough should pivot from the Dakotas across MN and Lake Superior to northeastern ON. As that occurs, convectively aided/induced vorticity lobes should move eastward across the upper Great Lakes. This includes a shortwave perturbation associated with a pronounced MCV now located over southern WI, and extending south-southwestward behind a band of convection across southern WI and northwestern IL. The 11Z surface chart showed a low near EAU, related to the MCV, with wavy warm front extending across western/southern WI and southern Lower MI. This front should drift northward before being overtaken by an ongoing MCS and additional convection developing farther east. A cold front was drawn from southeastern MN across southeastern NE and northwestern KS. By 00Z this front should reach eastern Upper MI, central WI, southern IA, central/southwestern KS, and southeastern CO. By 12Z this front should extend from northern Lower MI to northern IL, central/western MO, northwestern OK, becoming quasistationary northwestward into southeastern CO. ...Great Lakes vicinity... An intermittently organized band of convection, continuing eastward from overnight activity across IA, has persisted across the Mississippi River the past couple hours. Some of this activity may strengthen across the remainder of the northern IL/southern WI/Lake Michigan region eastward over northern IN and southern lower MI, as the foregoing/inflow-layer air mass destabilizes from a combination of warm advection and diabatic surface heating. Recovery behind newer convection over northeastern IL is uncertain in magnitude and northern extent. See SPC severe thunderstorm watch 597 and related mesoscale discussions for near-term details. In concert with seasonally steep low/middle-level lapse rates and rich low-level moisture (60s to near 70 F surface dew points), areas of 2000-3000 J/kg preconvective MLCAPE are expected to develop. This will occur amidst difluent but generally westerly mid/upper winds, enhanced on the mesoscale by height falls related to the MCV, and a plume of large-scale DCVA/lift preceding the shortwave trough. As the heating continues, MLCINH effectively will vanish over northeastern IL and eastward through midday, potentially fostering additional convective development and severe potential in and near the watch area, regardless of the morphology of the initial MCS. Subsequent aggregation and upscale growth should shift the primary threat of damaging winds across lower MI and northern IN. In addition, areas of relatively maximized effective SRH may support localized tornado potential in QLCS circulations. ...Ozarks to portions of OK... Isolated to scattered thunderstorms, with highly variable coverage in space and time, are possible through the overnight period across this region. Activity should be concentrated mainly near outflow/ differential-heating boundaries area-wide and near a weak convergence zone over the southwestern OK/northwest TX region this afternoon. Isolated severe gusts and hail may occur, with well- mixed air below LFC developing this afternoon, and persisting into tonight above a slowly stabilizing near-surface layer, aiding in maintenance of hail/gusts to surface. A relative concentration in severe potential also may become apparent this afternoon over portions of this region, especially in the Ozarks/eastern OK/southeastern KS area. Beneath steep midlevel lapse rates, pockets of relatively convectively undisturbed boundary-layer moisture and strong heating may support MLCAPE around 4000 J/kg. Uncertainties regarding location, orientation, and strength of supportive mesoscale boundaries preclude a more- concentrated area of unconditional probabilities at this time. ..Edwards/Marsh.. 08/18/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0756 AM CDT Sun Aug 18 2019 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE SOUTHERN UPPER GREAT LAKES AND VICINITY... ...SUMMARY... The main severe-thunderstorm threat today will be damaging winds, isolated hail and a few tornadoes are possible. ...Synopsis... In mid/upper levels, a belt of zonal to gently cyclonic mean flow will be observed through the period across the northern half of the CONUS. As a cyclone moves slowly northeastward across northern MB, the trailing shortwave trough should pivot from the Dakotas across MN and Lake Superior to northeastern ON. As that occurs, convectively aided/induced vorticity lobes should move eastward across the upper Great Lakes. This includes a shortwave perturbation associated with a pronounced MCV now located over southern WI, and extending south-southwestward behind a band of convection across southern WI and northwestern IL. The 11Z surface chart showed a low near EAU, related to the MCV, with wavy warm front extending across western/southern WI and southern Lower MI. This front should drift northward before being overtaken by an ongoing MCS and additional convection developing farther east. A cold front was drawn from southeastern MN across southeastern NE and northwestern KS. By 00Z this front should reach eastern Upper MI, central WI, southern IA, central/southwestern KS, and southeastern CO. By 12Z this front should extend from northern Lower MI to northern IL, central/western MO, northwestern OK, becoming quasistationary northwestward into southeastern CO. ...Great Lakes vicinity... An intermittently organized band of convection, continuing eastward from overnight activity across IA, has persisted across the Mississippi River the past couple hours. Some of this activity may strengthen across the remainder of the northern IL/southern WI/Lake Michigan region eastward over northern IN and southern lower MI, as the foregoing/inflow-layer air mass destabilizes from a combination of warm advection and diabatic surface heating. Recovery behind newer convection over northeastern IL is uncertain in magnitude and northern extent. See SPC severe thunderstorm watch 597 and related mesoscale discussions for near-term details. In concert with seasonally steep low/middle-level lapse rates and rich low-level moisture (60s to near 70 F surface dew points), areas of 2000-3000 J/kg preconvective MLCAPE are expected to develop. This will occur amidst difluent but generally westerly mid/upper winds, enhanced on the mesoscale by height falls related to the MCV, and a plume of large-scale DCVA/lift preceding the shortwave trough. As the heating continues, MLCINH effectively will vanish over northeastern IL and eastward through midday, potentially fostering additional convective development and severe potential in and near the watch area, regardless of the morphology of the initial MCS. Subsequent aggregation and upscale growth should shift the primary threat of damaging winds across lower MI and northern IN. In addition, areas of relatively maximized effective SRH may support localized tornado potential in QLCS circulations. ...Ozarks to portions of OK... Isolated to scattered thunderstorms, with highly variable coverage in space and time, are possible through the overnight period across this region. Activity should be concentrated mainly near outflow/ differential-heating boundaries area-wide and near a weak convergence zone over the southwestern OK/northwest TX region this afternoon. Isolated severe gusts and hail may occur, with well- mixed air below LFC developing this afternoon, and persisting into tonight above a slowly stabilizing near-surface layer, aiding in maintenance of hail/gusts to surface. A relative concentration in severe potential also may become apparent this afternoon over portions of this region, especially in the Ozarks/eastern OK/southeastern KS area. Beneath steep midlevel lapse rates, pockets of relatively convectively undisturbed boundary-layer moisture and strong heating may support MLCAPE around 4000 J/kg. Uncertainties regarding location, orientation, and strength of supportive mesoscale boundaries preclude a more- concentrated area of unconditional probabilities at this time. ..Edwards/Marsh.. 08/18/2019 Read more

WW 0597 Status Updates
STATUS REPORT ON WW 597 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 15 NNW PIA TO 25 NE MLI TO 35 E MSN. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1787. ..MARSH..08/18/19 ATTN...WFO...DVN...LOT...IWX...GRR...MKX... STATUS REPORT FOR WS 597 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC007-011-031-037-043-063-073-089-091-093-097-099-103-111-141- 155-195-197-201-181340- IL . ILLINOIS COUNTIES INCLUDED ARE BOONE BUREAU COOK DE KALB DUPAGE GRUNDY HENRY KANE KANKAKEE KENDALL LAKE LA SALLE LEE MCHENRY OGLE PUTNAM WHITESIDE WILL WINNEBAGO INC039-049-073-085-087-089-091-099-111-113-127-131-141-149-151- 183-181340- IN . INDIANA COUNTIES INCLUDED ARE ELKHART FULTON JASPER KOSCIUSKO LAGRANGE LAKE Read more

MD 1787 CONCERNING SEVERE THUNDERSTORM WATCH 597... FOR SOUTHEAST WISCONSIN...NORTHEAST ILLINOIS...NORTHWEST INDIANA...AND SOUTHWEST MICHIGAN
Mesoscale Discussion 1787 NWS Storm Prediction Center Norman OK 0740 AM CDT Sun Aug 18 2019 Areas affected...southeast Wisconsin...northeast Illinois...northwest Indiana...and southwest Michigan Concerning...Severe Thunderstorm Watch 597... Valid 181240Z - 181445Z The severe weather threat for Severe Thunderstorm Watch 597 continues. SUMMARY...Thunderstorms continue this morning across the region. Moderate instability and sufficient shear should continue to support a severe threat this morning. DISCUSSION...Initial line of thunderstorms has weakened considerably this morning as increasing precipitation ahead of the line -- stemming from thunderstorms that developed south-southwest of Chicago -- has acted to stabilize the airmass across north-central Illinois and southern Wisconsin. The strongest thunderstorm cluster from this original band of storms is currently located across southeast Wisconsin and will have the potential to pose a severe threat for another couple hours before moving east over Lake Michigan. As previously mentioned, additional thunderstorms developed to the south-southwest of Chicago, ahead of the original line of storms. These thunderstorms are within a better severe thunderstorm environment than those to the north given less convective coverage allowing most-unstable CAPE values to approach 2000 J/kg, and thus have a greater potential to pose a severe wind or hail threat. At present, these storms will move across the greater Chicago metro over the next 1-2 hours, with hail and wind threats likely. These storms will continue east-northeast through the morning, eventually moving over Lake Michigan. ..Marsh.. 08/18/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DTX...IWX...GRR...LOT...ILX...MKX...DVN... LAT...LON 41049091 41209108 41419104 41449078 41599076 41599087 42029080 42069013 42489062 42508982 43228976 43318965 43308901 43208900 43188789 43358783 43408645 43468638 43458608 43288607 43298559 43408553 43438437 42808436 42778417 42068412 42058483 41528482 41538517 40998536 40968558 41048583 40928619 40908692 40738713 40728752 40988754 40998824 41098827 41088891 40908890 40928904 41078907 41098930 41138931 41128957 41228965 41228981 41118988 41149040 41049043 41049091 Read more

000
ABPZ20 KNHC 181147
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Sun Aug 18 2019

For the eastern North Pacific...east of 140 degrees west longitude:

Showers and thunderstorms associated with an area of low pressure
located a couple of hundred miles south-southwest of the coast of
Guatemala have changed little in organization since yesterday.
Environmental conditions are expected to become more conducive for
development during the next couple of days, and a tropical
depression is expected to form by Tuesday or Wednesday while the low
moves west-northwestward at about 10 mph parallel to the coast of
Mexico. Moisture associated with the low is forecast to produce
heavy rainfall and possible flash flooding across portions of El
Salvador, Guatemala, and southeastern Mexico during the next few
days.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 5 days...high...90 percent.

A tropical wave located about 900 miles south-southwest of the
southern tip of the Baja California peninsula is producing
disorganized shower and thunderstorm activity. Environmental
conditions continue to support slow development, and this system has
the potential to become a tropical cyclone by the middle of the week
while it moves westward to west-northwestward at about 10 mph.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...medium...40 percent.

Shower and thunderstorm activity near another tropical wave located
about 1300 miles west-southwest of the southern tip of the Baja
California peninsula has decreased since yesterday. Any
development of this system during the next couple of days is
expected to be slow to occur while it moves slowly westward at
about 10 mph.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...low...10 percent.

$$
Forecaster Berg