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SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0750 AM CDT Sun Sep 15 2024 Valid 151300Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN HIGH PLAINS... ...SUMMARY... Thunderstorms capable of isolated severe gusts and hail will be possible today across parts of the central and northern High Plains. ...Synopsis... In mid/upper levels, a blocky longwave pattern will remain over the CONUS, with amplifying troughing in the West and a Rex configuration in the East. Cyclonic flow already covers most of the land west of the Rockies. That will continue but with backing of the flow aloft, as a cyclone now centered over Vancouver Island strengthens and digs south-southeastward down the West Coast. By 12Z tomorrow, the associated 500-mb low should be located near OAK, with strongly difluent flow and modest ridging over the High Plains from eastern NM to MT. The southern part of a weak shortwave trough -- evident in moisture-channel imagery from UT to eastern AZ -- should cross CO today and reach the eastern border of WY to near GLD by 12Z, likely enhanced from this evening onward by convectively generated vorticity. A mid/upper anticyclone now over the Lower Great Lakes will stretch eastward and open up to that direction around the end of the period. The base of the eastern pattern block will be composed of a broad, nearly zonal height weakness anchored by: 1. The decaying remains of Francine, long merged with a mid/upper low, and forecast to drift erratically over the Mid-South while weakening further; 2. An intensifying, deep-layer cyclone with low-level manifestation as a deepening wave cyclone along a frontal zone, offshore from the Carolinas. The 11Z surface analysis showed a wavy, quasistationary frontal zone attached to a strengthening low located roughly south of EWN and east of SAV. The front extended across northern FL to the western FL Panhandle and southwestern AL. A remnant low was drawn well inland over northern MS, connecting to the Gulf boundary via an occluded front. These features should move little through the period, but with further weakening of the western low, and intensification of the eastern one. Elsewhere, a lee trough and dryline either overlapped, or were drawn within less than 100 nm apart, near the eastern border of WY, eastern CO, the northern/ western TX Panhandle, and east-central/southeastern NM. The dryline should shift somewhat eastward today amid diurnal heating. ...Central/northern High Plains... Isolated to widely scattered thunderstorms are possible across a large part of the Rockies, Intermountain West, and Desert Southwest today. Some of this activity will mature atop deep, well-mixed boundary layers of desert valleys and the High Plains, with non-zero potential for a strong-severe gust. The most concentrated/organized potential for gusts near to above severe limits, as well as marginal hail, still appears to be over portions of the central High Plains into the Black Hills and vicinity, near the lee trough/dryline. East of that, low-level moisture will be relatively maximized in a return-flow airmass of predominantly continental origin, with a north-south belt of 50s to mid 60s F surface dewpoints. Where the western part of that moisture coincides with strong surface heating, and underlies the eastern part of the EML, a north-south corridor of MLCAPE in the 1500-2500 J/kg range should develop, with 500-1500 J/kg extending into the more deeply mixed regime nearest the lee trough. East of the trough, considerable veering of winds with height is expected, with some low-level hodograph enhancement potentially moving 0-3-km SRH to near 150 J/kg, but lack of stronger midlevel flow will temper overall shear. ...Coastal NC, extreme eastern SC... Many progs deepen the low-level cyclone and transition it to subtropical or tropical character through the end of day 2, while eroding the frontal zone's baroclinicity; however, inconsistency among models is high. The most aggressive among the synoptic and CAM guidance with the speed of the transition and approach to the coast (e.g., 06Z GFS and 00Z ARW high-res window respectively) show favorably large low-level shear, but barely have surface-based effective inflow onshore at the end of the period, with greatest convective coverage and buoyancy still offshore. As such, the associated coastal tornado threat still appears too low and conditional to outlook until day 2 (after 16/12Z). Potential for faster/deeper development and shoreward translation of the low will continue to be monitored for onshore supercell threat the last few hours of day 1. See latest NHC tropical outlook for guidance on overall development potential with this system. ..Edwards/Mosier.. 09/15/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0750 AM CDT Sun Sep 15 2024 Valid 151300Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN HIGH PLAINS... ...SUMMARY... Thunderstorms capable of isolated severe gusts and hail will be possible today across parts of the central and northern High Plains. ...Synopsis... In mid/upper levels, a blocky longwave pattern will remain over the CONUS, with amplifying troughing in the West and a Rex configuration in the East. Cyclonic flow already covers most of the land west of the Rockies. That will continue but with backing of the flow aloft, as a cyclone now centered over Vancouver Island strengthens and digs south-southeastward down the West Coast. By 12Z tomorrow, the associated 500-mb low should be located near OAK, with strongly difluent flow and modest ridging over the High Plains from eastern NM to MT. The southern part of a weak shortwave trough -- evident in moisture-channel imagery from UT to eastern AZ -- should cross CO today and reach the eastern border of WY to near GLD by 12Z, likely enhanced from this evening onward by convectively generated vorticity. A mid/upper anticyclone now over the Lower Great Lakes will stretch eastward and open up to that direction around the end of the period. The base of the eastern pattern block will be composed of a broad, nearly zonal height weakness anchored by: 1. The decaying remains of Francine, long merged with a mid/upper low, and forecast to drift erratically over the Mid-South while weakening further; 2. An intensifying, deep-layer cyclone with low-level manifestation as a deepening wave cyclone along a frontal zone, offshore from the Carolinas. The 11Z surface analysis showed a wavy, quasistationary frontal zone attached to a strengthening low located roughly south of EWN and east of SAV. The front extended across northern FL to the western FL Panhandle and southwestern AL. A remnant low was drawn well inland over northern MS, connecting to the Gulf boundary via an occluded front. These features should move little through the period, but with further weakening of the western low, and intensification of the eastern one. Elsewhere, a lee trough and dryline either overlapped, or were drawn within less than 100 nm apart, near the eastern border of WY, eastern CO, the northern/ western TX Panhandle, and east-central/southeastern NM. The dryline should shift somewhat eastward today amid diurnal heating. ...Central/northern High Plains... Isolated to widely scattered thunderstorms are possible across a large part of the Rockies, Intermountain West, and Desert Southwest today. Some of this activity will mature atop deep, well-mixed boundary layers of desert valleys and the High Plains, with non-zero potential for a strong-severe gust. The most concentrated/organized potential for gusts near to above severe limits, as well as marginal hail, still appears to be over portions of the central High Plains into the Black Hills and vicinity, near the lee trough/dryline. East of that, low-level moisture will be relatively maximized in a return-flow airmass of predominantly continental origin, with a north-south belt of 50s to mid 60s F surface dewpoints. Where the western part of that moisture coincides with strong surface heating, and underlies the eastern part of the EML, a north-south corridor of MLCAPE in the 1500-2500 J/kg range should develop, with 500-1500 J/kg extending into the more deeply mixed regime nearest the lee trough. East of the trough, considerable veering of winds with height is expected, with some low-level hodograph enhancement potentially moving 0-3-km SRH to near 150 J/kg, but lack of stronger midlevel flow will temper overall shear. ...Coastal NC, extreme eastern SC... Many progs deepen the low-level cyclone and transition it to subtropical or tropical character through the end of day 2, while eroding the frontal zone's baroclinicity; however, inconsistency among models is high. The most aggressive among the synoptic and CAM guidance with the speed of the transition and approach to the coast (e.g., 06Z GFS and 00Z ARW high-res window respectively) show favorably large low-level shear, but barely have surface-based effective inflow onshore at the end of the period, with greatest convective coverage and buoyancy still offshore. As such, the associated coastal tornado threat still appears too low and conditional to outlook until day 2 (after 16/12Z). Potential for faster/deeper development and shoreward translation of the low will continue to be monitored for onshore supercell threat the last few hours of day 1. See latest NHC tropical outlook for guidance on overall development potential with this system. ..Edwards/Mosier.. 09/15/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0750 AM CDT Sun Sep 15 2024 Valid 151300Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN HIGH PLAINS... ...SUMMARY... Thunderstorms capable of isolated severe gusts and hail will be possible today across parts of the central and northern High Plains. ...Synopsis... In mid/upper levels, a blocky longwave pattern will remain over the CONUS, with amplifying troughing in the West and a Rex configuration in the East. Cyclonic flow already covers most of the land west of the Rockies. That will continue but with backing of the flow aloft, as a cyclone now centered over Vancouver Island strengthens and digs south-southeastward down the West Coast. By 12Z tomorrow, the associated 500-mb low should be located near OAK, with strongly difluent flow and modest ridging over the High Plains from eastern NM to MT. The southern part of a weak shortwave trough -- evident in moisture-channel imagery from UT to eastern AZ -- should cross CO today and reach the eastern border of WY to near GLD by 12Z, likely enhanced from this evening onward by convectively generated vorticity. A mid/upper anticyclone now over the Lower Great Lakes will stretch eastward and open up to that direction around the end of the period. The base of the eastern pattern block will be composed of a broad, nearly zonal height weakness anchored by: 1. The decaying remains of Francine, long merged with a mid/upper low, and forecast to drift erratically over the Mid-South while weakening further; 2. An intensifying, deep-layer cyclone with low-level manifestation as a deepening wave cyclone along a frontal zone, offshore from the Carolinas. The 11Z surface analysis showed a wavy, quasistationary frontal zone attached to a strengthening low located roughly south of EWN and east of SAV. The front extended across northern FL to the western FL Panhandle and southwestern AL. A remnant low was drawn well inland over northern MS, connecting to the Gulf boundary via an occluded front. These features should move little through the period, but with further weakening of the western low, and intensification of the eastern one. Elsewhere, a lee trough and dryline either overlapped, or were drawn within less than 100 nm apart, near the eastern border of WY, eastern CO, the northern/ western TX Panhandle, and east-central/southeastern NM. The dryline should shift somewhat eastward today amid diurnal heating. ...Central/northern High Plains... Isolated to widely scattered thunderstorms are possible across a large part of the Rockies, Intermountain West, and Desert Southwest today. Some of this activity will mature atop deep, well-mixed boundary layers of desert valleys and the High Plains, with non-zero potential for a strong-severe gust. The most concentrated/organized potential for gusts near to above severe limits, as well as marginal hail, still appears to be over portions of the central High Plains into the Black Hills and vicinity, near the lee trough/dryline. East of that, low-level moisture will be relatively maximized in a return-flow airmass of predominantly continental origin, with a north-south belt of 50s to mid 60s F surface dewpoints. Where the western part of that moisture coincides with strong surface heating, and underlies the eastern part of the EML, a north-south corridor of MLCAPE in the 1500-2500 J/kg range should develop, with 500-1500 J/kg extending into the more deeply mixed regime nearest the lee trough. East of the trough, considerable veering of winds with height is expected, with some low-level hodograph enhancement potentially moving 0-3-km SRH to near 150 J/kg, but lack of stronger midlevel flow will temper overall shear. ...Coastal NC, extreme eastern SC... Many progs deepen the low-level cyclone and transition it to subtropical or tropical character through the end of day 2, while eroding the frontal zone's baroclinicity; however, inconsistency among models is high. The most aggressive among the synoptic and CAM guidance with the speed of the transition and approach to the coast (e.g., 06Z GFS and 00Z ARW high-res window respectively) show favorably large low-level shear, but barely have surface-based effective inflow onshore at the end of the period, with greatest convective coverage and buoyancy still offshore. As such, the associated coastal tornado threat still appears too low and conditional to outlook until day 2 (after 16/12Z). Potential for faster/deeper development and shoreward translation of the low will continue to be monitored for onshore supercell threat the last few hours of day 1. See latest NHC tropical outlook for guidance on overall development potential with this system. ..Edwards/Mosier.. 09/15/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0750 AM CDT Sun Sep 15 2024 Valid 151300Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN HIGH PLAINS... ...SUMMARY... Thunderstorms capable of isolated severe gusts and hail will be possible today across parts of the central and northern High Plains. ...Synopsis... In mid/upper levels, a blocky longwave pattern will remain over the CONUS, with amplifying troughing in the West and a Rex configuration in the East. Cyclonic flow already covers most of the land west of the Rockies. That will continue but with backing of the flow aloft, as a cyclone now centered over Vancouver Island strengthens and digs south-southeastward down the West Coast. By 12Z tomorrow, the associated 500-mb low should be located near OAK, with strongly difluent flow and modest ridging over the High Plains from eastern NM to MT. The southern part of a weak shortwave trough -- evident in moisture-channel imagery from UT to eastern AZ -- should cross CO today and reach the eastern border of WY to near GLD by 12Z, likely enhanced from this evening onward by convectively generated vorticity. A mid/upper anticyclone now over the Lower Great Lakes will stretch eastward and open up to that direction around the end of the period. The base of the eastern pattern block will be composed of a broad, nearly zonal height weakness anchored by: 1. The decaying remains of Francine, long merged with a mid/upper low, and forecast to drift erratically over the Mid-South while weakening further; 2. An intensifying, deep-layer cyclone with low-level manifestation as a deepening wave cyclone along a frontal zone, offshore from the Carolinas. The 11Z surface analysis showed a wavy, quasistationary frontal zone attached to a strengthening low located roughly south of EWN and east of SAV. The front extended across northern FL to the western FL Panhandle and southwestern AL. A remnant low was drawn well inland over northern MS, connecting to the Gulf boundary via an occluded front. These features should move little through the period, but with further weakening of the western low, and intensification of the eastern one. Elsewhere, a lee trough and dryline either overlapped, or were drawn within less than 100 nm apart, near the eastern border of WY, eastern CO, the northern/ western TX Panhandle, and east-central/southeastern NM. The dryline should shift somewhat eastward today amid diurnal heating. ...Central/northern High Plains... Isolated to widely scattered thunderstorms are possible across a large part of the Rockies, Intermountain West, and Desert Southwest today. Some of this activity will mature atop deep, well-mixed boundary layers of desert valleys and the High Plains, with non-zero potential for a strong-severe gust. The most concentrated/organized potential for gusts near to above severe limits, as well as marginal hail, still appears to be over portions of the central High Plains into the Black Hills and vicinity, near the lee trough/dryline. East of that, low-level moisture will be relatively maximized in a return-flow airmass of predominantly continental origin, with a north-south belt of 50s to mid 60s F surface dewpoints. Where the western part of that moisture coincides with strong surface heating, and underlies the eastern part of the EML, a north-south corridor of MLCAPE in the 1500-2500 J/kg range should develop, with 500-1500 J/kg extending into the more deeply mixed regime nearest the lee trough. East of the trough, considerable veering of winds with height is expected, with some low-level hodograph enhancement potentially moving 0-3-km SRH to near 150 J/kg, but lack of stronger midlevel flow will temper overall shear. ...Coastal NC, extreme eastern SC... Many progs deepen the low-level cyclone and transition it to subtropical or tropical character through the end of day 2, while eroding the frontal zone's baroclinicity; however, inconsistency among models is high. The most aggressive among the synoptic and CAM guidance with the speed of the transition and approach to the coast (e.g., 06Z GFS and 00Z ARW high-res window respectively) show favorably large low-level shear, but barely have surface-based effective inflow onshore at the end of the period, with greatest convective coverage and buoyancy still offshore. As such, the associated coastal tornado threat still appears too low and conditional to outlook until day 2 (after 16/12Z). Potential for faster/deeper development and shoreward translation of the low will continue to be monitored for onshore supercell threat the last few hours of day 1. See latest NHC tropical outlook for guidance on overall development potential with this system. ..Edwards/Mosier.. 09/15/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0750 AM CDT Sun Sep 15 2024 Valid 151300Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN HIGH PLAINS... ...SUMMARY... Thunderstorms capable of isolated severe gusts and hail will be possible today across parts of the central and northern High Plains. ...Synopsis... In mid/upper levels, a blocky longwave pattern will remain over the CONUS, with amplifying troughing in the West and a Rex configuration in the East. Cyclonic flow already covers most of the land west of the Rockies. That will continue but with backing of the flow aloft, as a cyclone now centered over Vancouver Island strengthens and digs south-southeastward down the West Coast. By 12Z tomorrow, the associated 500-mb low should be located near OAK, with strongly difluent flow and modest ridging over the High Plains from eastern NM to MT. The southern part of a weak shortwave trough -- evident in moisture-channel imagery from UT to eastern AZ -- should cross CO today and reach the eastern border of WY to near GLD by 12Z, likely enhanced from this evening onward by convectively generated vorticity. A mid/upper anticyclone now over the Lower Great Lakes will stretch eastward and open up to that direction around the end of the period. The base of the eastern pattern block will be composed of a broad, nearly zonal height weakness anchored by: 1. The decaying remains of Francine, long merged with a mid/upper low, and forecast to drift erratically over the Mid-South while weakening further; 2. An intensifying, deep-layer cyclone with low-level manifestation as a deepening wave cyclone along a frontal zone, offshore from the Carolinas. The 11Z surface analysis showed a wavy, quasistationary frontal zone attached to a strengthening low located roughly south of EWN and east of SAV. The front extended across northern FL to the western FL Panhandle and southwestern AL. A remnant low was drawn well inland over northern MS, connecting to the Gulf boundary via an occluded front. These features should move little through the period, but with further weakening of the western low, and intensification of the eastern one. Elsewhere, a lee trough and dryline either overlapped, or were drawn within less than 100 nm apart, near the eastern border of WY, eastern CO, the northern/ western TX Panhandle, and east-central/southeastern NM. The dryline should shift somewhat eastward today amid diurnal heating. ...Central/northern High Plains... Isolated to widely scattered thunderstorms are possible across a large part of the Rockies, Intermountain West, and Desert Southwest today. Some of this activity will mature atop deep, well-mixed boundary layers of desert valleys and the High Plains, with non-zero potential for a strong-severe gust. The most concentrated/organized potential for gusts near to above severe limits, as well as marginal hail, still appears to be over portions of the central High Plains into the Black Hills and vicinity, near the lee trough/dryline. East of that, low-level moisture will be relatively maximized in a return-flow airmass of predominantly continental origin, with a north-south belt of 50s to mid 60s F surface dewpoints. Where the western part of that moisture coincides with strong surface heating, and underlies the eastern part of the EML, a north-south corridor of MLCAPE in the 1500-2500 J/kg range should develop, with 500-1500 J/kg extending into the more deeply mixed regime nearest the lee trough. East of the trough, considerable veering of winds with height is expected, with some low-level hodograph enhancement potentially moving 0-3-km SRH to near 150 J/kg, but lack of stronger midlevel flow will temper overall shear. ...Coastal NC, extreme eastern SC... Many progs deepen the low-level cyclone and transition it to subtropical or tropical character through the end of day 2, while eroding the frontal zone's baroclinicity; however, inconsistency among models is high. The most aggressive among the synoptic and CAM guidance with the speed of the transition and approach to the coast (e.g., 06Z GFS and 00Z ARW high-res window respectively) show favorably large low-level shear, but barely have surface-based effective inflow onshore at the end of the period, with greatest convective coverage and buoyancy still offshore. As such, the associated coastal tornado threat still appears too low and conditional to outlook until day 2 (after 16/12Z). Potential for faster/deeper development and shoreward translation of the low will continue to be monitored for onshore supercell threat the last few hours of day 1. See latest NHC tropical outlook for guidance on overall development potential with this system. ..Edwards/Mosier.. 09/15/2024 Read more

000
ABPZ20 KNHC 151138
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Sun Sep 15 2024

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

Active Systems:
The National Hurricane Center is issuing advisories on Tropical
Depression Ileana, located near the coast of northern Sinaloa,
Mexico.

Tropical cyclone formation is not expected during the next 7 days.

$$
Forecaster Kelly

5-Day Uncertainty Track last updated Sun, 15 Sep 2024 08:45:00 GMT


Wind Speed Probabilities last updated Sun, 15 Sep 2024 09:28:43 GMT

Issued at 200 AM MST Sun Sep 15 2024 064 WTPZ44 KNHC 150844 TCDEP4 Tropical Depression Ileana Discussion Number 12 NWS National Hurricane Center Miami FL EP092024 200 AM MST Sun Sep 15 2024 All of Ileana's deep convection dissipated yesterday afternoon, and all that is left now is a swirl of low clouds off the coast of northern Sinaloa. An ASCAT-C pass from 0410 UTC showed maximum winds near 30 kt over the Gulf of California near northern Sinaloa, and a weather station in Topolobampo is no longer reporting winds to tropical storm force. As a result, Ileana is now designated as a 30-kt tropical depression, and all coastal warnings in Mexico have been discontinued. Ileana has been meandering, but the longer-term motion is west-northwestward, or 300/2 kt. Model guidance indicates that the cyclone should turn northwestward later today but maintain a generally slow motion while moving over the Gulf of California. Due to strong southwesterly shear and a very dry atmosphere, deep convection is not expected to redevelop, and it's likely that Gordon will be declared a remnant low later this morning. The remnant low is expected to dissipate on Monday. FORECAST POSITIONS AND MAX WINDS INIT 15/0900Z 25.5N 109.3W 30 KT 35 MPH 12H 15/1800Z 25.8N 109.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 24H 16/0600Z 26.5N 110.4W 20 KT 25 MPH...POST-TROP/REMNT LOW 36H 16/1800Z...DISSIPATED $$ Forecaster Berg

Issued at 0900 UTC SUN SEP 15 2024 164 FOPZ14 KNHC 150843 PWSEP4 TROPICAL DEPRESSION ILEANA WIND SPEED PROBABILITIES NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL EP092024 0900 UTC SUN SEP 15 2024 AT 0900Z THE CENTER OF TROPICAL DEPRESSION ILEANA WAS LOCATED NEAR LATITUDE 25.5 NORTH...LONGITUDE 109.3 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 30 KTS...35 MPH...55 KM/H. Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH) PACIFIC DAYLIGHT TIME (PDT)...SUBTRACT 7 HOURS FROM Z TIME HAWAIIAN STANDARD TIME (HST)...SUBTRACT 10 HOURS FROM Z TIME WIND SPEED PROBABILITY TABLE FOR SPECIFIC LOCATIONS CHANCES OF SUSTAINED (1-MINUTE AVERAGE) WIND SPEEDS OF AT LEAST ...34 KT (39 MPH... 63 KM/H)... ...50 KT (58 MPH... 93 KM/H)... ...64 KT (74 MPH...119 KM/H)... FOR LOCATIONS AND TIME PERIODS DURING THE NEXT 5 DAYS PROBABILITIES FOR LOCATIONS ARE GIVEN AS OP(CP) WHERE OP IS THE PROBABILITY OF THE EVENT BEGINNING DURING AN INDIVIDUAL TIME PERIOD (ONSET PROBABILITY) (CP) IS THE PROBABILITY OF THE EVENT OCCURRING BETWEEN 06Z SUN AND THE FORECAST HOUR (CUMULATIVE PROBABILITY) PROBABILITIES ARE GIVEN IN PERCENT X INDICATES PROBABILITIES LESS THAN 1 PERCENT PROBABILITIES FOR 34 KT AND 50 KT ARE SHOWN AT A GIVEN LOCATION WHEN THE 5-DAY CUMULATIVE PROBABILITY IS AT LEAST 3 PERCENT. PROBABILITIES FOR 34...50...64 KT SHOWN WHEN THE 5-DAY 64-KT CUMULATIVE PROBABILITY IS AT LEAST 1 PERCENT. - - - - WIND SPEED PROBABILITIES FOR SELECTED LOCATIONS - - - - FROM FROM FROM FROM FROM FROM FROM TIME 06Z SUN 18Z SUN 06Z MON 18Z MON 06Z TUE 06Z WED 06Z THU PERIODS TO TO TO TO TO TO TO 18Z SUN 06Z MON 18Z MON 06Z TUE 06Z WED 06Z THU 06Z FRI FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT $$ FORECASTER BERG

Issued at 200 AM MST Sun Sep 15 2024 000 WTPZ34 KNHC 150843 TCPEP4 BULLETIN Tropical Depression Ileana Advisory Number 12 NWS National Hurricane Center Miami FL EP092024 200 AM MST Sun Sep 15 2024 ...ILEANA WEAKENS TO A TROPICAL DEPRESSION... ...FORECAST TO BECOME A REMNANT LOW LATER THIS MORNING... SUMMARY OF 200 AM MST...0900 UTC...INFORMATION ---------------------------------------------- LOCATION...25.5N 109.3W ABOUT 30 MI...45 KM SW OF LOS MOCHIS MEXICO MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...WNW OR 300 DEGREES AT 2 MPH...4 KM/H MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The government of Mexico has discontinued all coastal warnings. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: There are no coastal watches or warnings in effect. DISCUSSION AND OUTLOOK ---------------------- At 200 AM MST (0900 UTC), the center of Tropical Depression Ileana was located near latitude 25.5 North, longitude 109.3 West. Ileana is moving toward the west-northwest near 2 mph (4 km/h). A slow northwestward motion is expected to begin later today and continue through early Monday. On the forecast track, the center of Ileana will move over the Gulf of California near the coasts of northern Sinaloa and southern Sonora. Maximum sustained winds have decreased to near 35 mph (55 km/h) with higher gusts. Additional weakening is forecast, and Ileana is expected to become a remnant low later this morning. The remnant low is forecast to dissipate on Monday. The estimated minimum central pressure is 1006 mb (29.71 inches). HAZARDS AFFECTING LAND ---------------------- RAINFALL: Ileana may bring an additional 1 to 2 inches of rainfall to portions of northwest Sinaloa through today. For a complete depiction of forecast rainfall associated with Ileana, please see the National Weather Service Storm Total Rainfall Graphic, available at hurricanes.gov/graphics_ep4.shtml?rainqpf WIND: Gusty winds are still possible along the coasts of northern Sinaloa and southern Sonora through this morning. SURF: Swells generated by Ileana will continue to subside along the Gulf of California coasts of Sinaloa, southern Sonora, and southern Baja California Sur today. NEXT ADVISORY ------------- Next complete advisory at 800 AM MST. $$ Forecaster Berg

...ILEANA WEAKENS TO A TROPICAL DEPRESSION... ...FORECAST TO BECOME A REMNANT LOW LATER THIS MORNING... As of 2:00 AM MST Sun Sep 15 the center of Ileana was located near 25.5, -109.3 with movement WNW at 2 mph. The minimum central pressure was 1006 mb with maximum sustained winds of about 35 mph.

Issued at 200 AM MST Sun Sep 15 2024 ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM Tropical Depression Ileana Discussion Number 12 NWS National Hurricane Center Miami FL EP092024 200 AM MST Sun Sep 15 2024 All of Ileana's deep convection dissipated yesterday afternoon, and all that is left now is a swirl of low clouds off the coast of northern Sinaloa. An ASCAT-C pass from 0410 UTC showed maximum winds near 30 kt over the Gulf of California near northern Sinaloa, and a weather station in Topolobampo is no longer reporting winds to tropical storm force. As a result, Ileana is now designated as a 30-kt tropical depression, and all coastal warnings in Mexico have been discontinued. Ileana has been meandering, but the longer-term motion is west-northwestward, or 300/2 kt. Model guidance indicates that the cyclone should turn northwestward later today but maintain a generally slow motion while moving over the Gulf of California. Due to strong southwesterly shear and a very dry atmosphere, deep convection is not expected to redevelop, and it's likely that Gordon will be declared a remnant low later this morning. The remnant low is expected to dissipate on Monday. FORECAST POSITIONS AND MAX WINDS INIT 15/0900Z 25.5N 109.3W 30 KT 35 MPH 12H 15/1800Z 25.8N 109.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 24H 16/0600Z 26.5N 110.4W 20 KT 25 MPH...POST-TROP/REMNT LOW 36H 16/1800Z...DISSIPATED $$ Forecaster Berg NNNN

Issued at 0900 UTC SUN SEP 15 2024 376 WTPZ24 KNHC 150843 TCMEP4 TROPICAL DEPRESSION ILEANA FORECAST/ADVISORY NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL EP092024 0900 UTC SUN SEP 15 2024 TROPICAL DEPRESSION CENTER LOCATED NEAR 25.5N 109.3W AT 15/0900Z POSITION ACCURATE WITHIN 20 NM PRESENT MOVEMENT TOWARD THE WEST-NORTHWEST OR 300 DEGREES AT 2 KT ESTIMATED MINIMUM CENTRAL PRESSURE 1006 MB MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT. WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT. REPEAT...CENTER LOCATED NEAR 25.5N 109.3W AT 15/0900Z AT 15/0600Z CENTER WAS LOCATED NEAR 25.4N 109.3W FORECAST VALID 15/1800Z 25.8N 109.8W...POST-TROP/REMNT LOW MAX WIND 25 KT...GUSTS 35 KT. FORECAST VALID 16/0600Z 26.5N 110.4W...POST-TROP/REMNT LOW MAX WIND 20 KT...GUSTS 30 KT. FORECAST VALID 16/1800Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 25.5N 109.3W NEXT ADVISORY AT 15/1500Z $$ FORECASTER BERG

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0334 AM CDT Sun Sep 15 2024 Valid 181200Z - 231200Z ...DISCUSSION... A shortwave trough near the northern High Plains at 12Z Wednesday should slow as it largely progresses across the southern Prairie Provinces. A belt of enhanced mid-level southwesterlies should linger over the northern Great Plains through Thursday, and aid in a recharging and downstream advection of steep mid-level lapse rates over the Dakotas and NE. The low-level moisture plume near the edge of the EML should be confined, as dry conditions persist in the Great Lakes region, on the backside of the low-amplitude mid-level trough over the East. Low-probability severe may occur along a portion of a weak cold front on Thursday in the north-central states. The next shortwave trough that amplifies into the Southwest should remain positive tilt and slow moving, until around next weekend when guidance consensus suggests it accelerates northeastward as another shortwave trough digs into the Northwest. This pattern should yield more muted mid-level lapse rates over most of the Great Plains, especially into next weekend. As such, severe probabilities may remain low through the period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0334 AM CDT Sun Sep 15 2024 Valid 181200Z - 231200Z ...DISCUSSION... A shortwave trough near the northern High Plains at 12Z Wednesday should slow as it largely progresses across the southern Prairie Provinces. A belt of enhanced mid-level southwesterlies should linger over the northern Great Plains through Thursday, and aid in a recharging and downstream advection of steep mid-level lapse rates over the Dakotas and NE. The low-level moisture plume near the edge of the EML should be confined, as dry conditions persist in the Great Lakes region, on the backside of the low-amplitude mid-level trough over the East. Low-probability severe may occur along a portion of a weak cold front on Thursday in the north-central states. The next shortwave trough that amplifies into the Southwest should remain positive tilt and slow moving, until around next weekend when guidance consensus suggests it accelerates northeastward as another shortwave trough digs into the Northwest. This pattern should yield more muted mid-level lapse rates over most of the Great Plains, especially into next weekend. As such, severe probabilities may remain low through the period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0334 AM CDT Sun Sep 15 2024 Valid 181200Z - 231200Z ...DISCUSSION... A shortwave trough near the northern High Plains at 12Z Wednesday should slow as it largely progresses across the southern Prairie Provinces. A belt of enhanced mid-level southwesterlies should linger over the northern Great Plains through Thursday, and aid in a recharging and downstream advection of steep mid-level lapse rates over the Dakotas and NE. The low-level moisture plume near the edge of the EML should be confined, as dry conditions persist in the Great Lakes region, on the backside of the low-amplitude mid-level trough over the East. Low-probability severe may occur along a portion of a weak cold front on Thursday in the north-central states. The next shortwave trough that amplifies into the Southwest should remain positive tilt and slow moving, until around next weekend when guidance consensus suggests it accelerates northeastward as another shortwave trough digs into the Northwest. This pattern should yield more muted mid-level lapse rates over most of the Great Plains, especially into next weekend. As such, severe probabilities may remain low through the period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0334 AM CDT Sun Sep 15 2024 Valid 181200Z - 231200Z ...DISCUSSION... A shortwave trough near the northern High Plains at 12Z Wednesday should slow as it largely progresses across the southern Prairie Provinces. A belt of enhanced mid-level southwesterlies should linger over the northern Great Plains through Thursday, and aid in a recharging and downstream advection of steep mid-level lapse rates over the Dakotas and NE. The low-level moisture plume near the edge of the EML should be confined, as dry conditions persist in the Great Lakes region, on the backside of the low-amplitude mid-level trough over the East. Low-probability severe may occur along a portion of a weak cold front on Thursday in the north-central states. The next shortwave trough that amplifies into the Southwest should remain positive tilt and slow moving, until around next weekend when guidance consensus suggests it accelerates northeastward as another shortwave trough digs into the Northwest. This pattern should yield more muted mid-level lapse rates over most of the Great Plains, especially into next weekend. As such, severe probabilities may remain low through the period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0334 AM CDT Sun Sep 15 2024 Valid 181200Z - 231200Z ...DISCUSSION... A shortwave trough near the northern High Plains at 12Z Wednesday should slow as it largely progresses across the southern Prairie Provinces. A belt of enhanced mid-level southwesterlies should linger over the northern Great Plains through Thursday, and aid in a recharging and downstream advection of steep mid-level lapse rates over the Dakotas and NE. The low-level moisture plume near the edge of the EML should be confined, as dry conditions persist in the Great Lakes region, on the backside of the low-amplitude mid-level trough over the East. Low-probability severe may occur along a portion of a weak cold front on Thursday in the north-central states. The next shortwave trough that amplifies into the Southwest should remain positive tilt and slow moving, until around next weekend when guidance consensus suggests it accelerates northeastward as another shortwave trough digs into the Northwest. This pattern should yield more muted mid-level lapse rates over most of the Great Plains, especially into next weekend. As such, severe probabilities may remain low through the period. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Sun Sep 15 2024 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN THE HIGH PLAINS... ...SUMMARY... Isolated severe thunderstorms will be possible across a large swath of the High Plains region, mainly from Tuesday late afternoon into the evening. Severe gusts should be the primary hazard. ...High Plains... A shortwave trough over the eastern Great Basin at 12Z Tuesday should take on a negative tilt as it advances towards the northern High Plains. This process will yield a separation of the strong upper-level jet surrounding the trough, from a meridional component shifting north into eastern WY and a zonal component holding over AZ/NM. Guidance has oscillated southward with the evolution of the meridional component relative to yesterday's guidance. Deep lee cyclogenesis is expected over northeast WY/southeast MT. This low will advance north towards the MT/SK border area by 12Z Wednesday. Large-scale ascent will be pronounced within this synoptic regime, with favorable upper-level difluence, mid-level height falls, and low-level convergence. But weak buoyancy and modest mid-level lapse rates will characterized much of the environment. The bulk of convective development will occur over the higher terrain, likely aided by the subtropical moisture plume over the Southwest. High-based storms should progress into a well-mixed boundary layer that may initially be devoid of appreciable CAPE. This lack of greater buoyancy during the late afternoon to early evening, outside of northeast MT into the Dakotas, yields substantial uncertainty in the degree of strong versus severe storms. But with scattered to widespread convection likely into the evening, sporadic severe gusts may occur. ...Eastern NC and southeast VA... The poor predictability of offshore cyclogenesis amplitude and inland progression on Monday renders minimal confidence in delineating a severe area on Tuesday. Slower and more aggressive ensemble members suggest an adequate SRH/buoyancy combination for low-topped tornado potential may linger over eastern NC early in the period and shift into parts of southeast VA. But overall trends indicate a generalized weakening low-level wind field may occur during the day. ..Grams.. 09/15/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Sun Sep 15 2024 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN THE HIGH PLAINS... ...SUMMARY... Isolated severe thunderstorms will be possible across a large swath of the High Plains region, mainly from Tuesday late afternoon into the evening. Severe gusts should be the primary hazard. ...High Plains... A shortwave trough over the eastern Great Basin at 12Z Tuesday should take on a negative tilt as it advances towards the northern High Plains. This process will yield a separation of the strong upper-level jet surrounding the trough, from a meridional component shifting north into eastern WY and a zonal component holding over AZ/NM. Guidance has oscillated southward with the evolution of the meridional component relative to yesterday's guidance. Deep lee cyclogenesis is expected over northeast WY/southeast MT. This low will advance north towards the MT/SK border area by 12Z Wednesday. Large-scale ascent will be pronounced within this synoptic regime, with favorable upper-level difluence, mid-level height falls, and low-level convergence. But weak buoyancy and modest mid-level lapse rates will characterized much of the environment. The bulk of convective development will occur over the higher terrain, likely aided by the subtropical moisture plume over the Southwest. High-based storms should progress into a well-mixed boundary layer that may initially be devoid of appreciable CAPE. This lack of greater buoyancy during the late afternoon to early evening, outside of northeast MT into the Dakotas, yields substantial uncertainty in the degree of strong versus severe storms. But with scattered to widespread convection likely into the evening, sporadic severe gusts may occur. ...Eastern NC and southeast VA... The poor predictability of offshore cyclogenesis amplitude and inland progression on Monday renders minimal confidence in delineating a severe area on Tuesday. Slower and more aggressive ensemble members suggest an adequate SRH/buoyancy combination for low-topped tornado potential may linger over eastern NC early in the period and shift into parts of southeast VA. But overall trends indicate a generalized weakening low-level wind field may occur during the day. ..Grams.. 09/15/2024 Read more