During the afternoon of July 13th, a cluster of thunderstorms developed in East-Central Colorado and moved south-southeastward across the region. One of these thunderstorms became severe and produced hail up to baseballs in size within the region.
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The episode as NWS GLD wrote it up.
During the afternoon of July 13th, a cluster of thunderstorms developed in East-Central Colorado and moved south-southeastward across the region. One of these thunderstorms became severe and produced hail up to baseballs in size within the region.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Goodland, KS wrote its last area forecast discussion before the first event at Jul 13, 10:28 AM MST, 1 hour 37 minutes earlier.
Area Forecast Discussion National Weather Service Goodland KS 1128 AM MDT Thu Jul 13 2023 .SHORT TERM...(Today through Saturday night) Issued at 445 AM MDT Thu Jul 13 2023 Synoptic Overview: A flattened upper level ridge -- presently situated over the Desert Southwest and Southern Plains -- will gradually amplify and migrate westward to the Pacific Coast this weekend. Today-Tonight: Challenging convective forecast. The Tri-State area will remain on the southern fringe of the mid-latitude westerlies.. on the northern periphery of the aforementioned ridge.. amidst a somewhat typical/climatological (albeit poorly- defined) low-level pattern characterized by a weak/broad lee surface trough in Colorado and modest southerly return flow in far western KS. At 0930 UTC this morning, a NW-SE oriented line of convection -- extending (roughly) ~200 miles from Alliance-North Platte-Lexington, NE -- was ongoing and intensifying. Simulated reflectivity forecasts via current and recent runs of the HRRR suggest that outflow /rain-cooled airmass/ emanating from the aforementioned convective will progress southward into southwest NE and northwest KS this morning.. possibly aiding in the development of scattered convection north and northeast of Goodland between 12-16Z.. or, at the very least.. altering low- level height/wind fields and the thermodynamic environment -- increasing forecast complexity (and decreasing forecast confidence). Simulated REF forecasts via the HRRR suggest that low-level convergence invof the dryline may be sufficient for isold convective development around peak heating (~20-21Z) in eastern CO (Yuma-Kit Carson) -- where rich low-level moisture (60-65F dewpoints) and steep mid-level lapse rates (8-9 C/km) associated with a recovering elevated mixed layer /EML/ will foster strong instability (2500-3500 J/kg MLCAPE) in the presence of strong /40-50 KT/ effective deep layer shear. With this in mind.. expect a potential for robust supercells capable of producing very large hail and damaging winds.. mainly in eastern CO and extreme western KS between 20-03 UTC (2-9 pm MDT). With right-mover motion from the NNW (330-350 degrees).. expect storm motion (generally) toward the SE-SSE. Anticyclonic splits (if any), would track toward the NE-ENE (left-mover motion from the SW-WSW, or 230-250 degrees). Fri-Fri night: W flow aloft will veer to the NW in this period.. as the aforementioned ridge retrogrades west toward the Pacific Coast and amplifies /extends northward/ through the Intermountain West and PAC NW. Guidance suggests small amplitude waves in WNW-NW flow aloft may aid convective development in south-central Nebraska Fri afternoon.. with activity propagating southward into central/eastern Kansas (toward an untapped, strongly unstable airmass) Fri evening -- largely missing and/or circumventing the Tri-State area -- though, this may be somewhat dependent upon prior convective evolution and airmass modification. Sat-Sat night: NW flow aloft may tend to promote surface troughing/cyclogenesis in the lee of the southern Rockies (e.g. NM) in this period -- particularly in the wake of widespread convection propagating southward from the Central to Southern Plains Fri eve/night. Expect relatively cooler temperatures and [overall] decreased potential for convection. .LONG TERM...(Sunday through Wednesday) Issued at 120 AM MDT Thu Jul 13 2023 This mornings guidance (GFS/GEM/ECMWF/GEFS) suggests that a weather disturbance moves out of east central Wyoming and into our forecast area east of the CO/KS border Sunday late afternoon through the overnight hours, supporting NBM model slight chance pops. High temperatures are forecast to be in the middle 80s to lower 90s with low temperatures in the 60 to 65 degree range. On Monday, 500mb heights rise slightly as the upper ridge broadens a bit from its center over Arizona/New Mexico. This slight shift in the upper pattern pushes any appreciable moisture needed for rainfall just out of the area per 850-500mb relative humidity forecasts from the GFS/GEM/ECMWF models. High temperatures are forecast to be in the 90 to 95 degree range. If we have full mixing to 850mb, we could see highs about 4F higher. Low temperatures fall into the lower to middle 60s. The upper ridge axis spreads further east Tuesday and with low pressure moving toward North Dakota, the flow aloft becomes nearly zonal. There is pretty good agreement between the GFS/GEM/ECMWF models in bringing a weather system through the area from the Cheyenne Ridge area during the mid afternoon through midnight hours, supporting some slight chance to low chance pops for thunderstorms. High temperatures are forecast to be in the 90 to 95 degree range with low temperatures in the lower 60s to around 70. Subtle changes at 500mb Wednesday, nothing worth really mentioning. We'll have another chance of afternoon through midnight thunderstorms. High temperatures generally remain in the lower to middle 90s with low temperatures in the lower 60s to around 70. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) Issued at 1127 AM MDT Thu Jul 13 2023 Mid to low level clouds through the middle of the day are expected to keep both KGLD and KMCK hovering around the MVFR and IFR ceiling criteria. Thunderstorms are expected this afternoon, generally between 21 & 5Z. Fog overnight is possible again with potential impacts more likely at the KGLD site. There is another potential round of storms for tomorrow afternoon. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && SHORT TERM...Vincent LONG TERM...99 AVIATION...JN/CA
Hazardous Weather Outlook National Weather Service Goodland KS 1229 PM MDT Thu Jul 13 2023 COZ090>092-KSZ001>004-013>016-027>029-041-042-NEZ079>081-141830- Yuma-Kit Carson-Cheyenne-Rawlins-Decatur-Norton-Sherman-Thomas- Sheridan-Graham-Wallace-Logan-Gove-Greeley-Wichita-Dundy-Hitchcock- Red Willow- 1229 PM MDT Thu Jul 13 2023 /129 PM CDT Thu Jul 13 2023/ This hazardous weather outlook is for extreme southwest Nebraska... northwest Kansas and east central Colorado. .DAY ONE...TODAY AND TONIGHT... A Severe Thunderstorm Watch has been issued for portions of eastern Colorado, southwest Nebraska, and northwestern Kansas until 8 PM MDT. Isolated severe thunderstorms capable of producing large hail and damaging winds are possible this afternoon into this evening, mainly in eastern Colorado and adjacent Kansas and Nebraska border counties between 2 PM and 9 PM MDT. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH THURSDAY... Scattered thunderstorms may develop along and east of Highway 83 Friday afternoon. While an isolated severe storm cannot be ruled out, severe weather may largely be confined southeast of the Tri- State area, over portions of central and southern Kansas. .SPOTTER INFORMATION STATEMENT... Spotter activation may be required.
Special Weather Statement National Weather Service Goodland KS 710 AM MDT Thu Jul 13 2023 COZ090>092-KSZ001>004-013>016-027>029-041-042-NEZ079>081-131515- Yuma-Kit Carson-Cheyenne-Rawlins-Decatur-Norton-Sherman-Thomas- Sheridan-Graham-Wallace-Logan-Gove-Greeley-Wichita-Dundy- Hitchcock-Red Willow- Including the cities of Yuma, Wray, Burlington, Arapahoe, Cheyenne Wells, St. Francis, Bird City, Atwood, Oberlin, Norton, Goodland, Colby, Hoxie, Hill City, Sharon Springs, Oakley, Quinter, Grinnell, Grainfield, Tribune, Leoti, Benkelman, Culbertson, Trenton, Stratton Ne, Palisade, and McCook 710 AM MDT Thu Jul 13 2023 /810 AM CDT Thu Jul 13 2023/ Patchy to dense fog is moving across the Tri-State area with localized visibility reductions down to 1/4 mile. Widespread reductions of visibility to under 6 miles have been reported across the area. CA
Preliminary Local Storm Report
National Weather Service Goodland KS
737 AM MDT Thu Jul 13 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0735 AM Fog 1 WSW Goodland 39.34N 101.73W
07/13/2023 E0.25 mi Sherman KS Public
Frontier Ag Camera at intersection of Hwy
24/27.
&&
JNThe Goodland radar (KGLD), 101 km away, was scanning. The volume nearest the first event began at 19:05 UTC.
4 hail. Local standard time, as filed.
At 1:39PM MDT, report received that a few baseball sized hailstones fell at location. Hail averaged between one-quarter to three-quarters of an inch in diameter and began about 30-45 minutes ago at location. Time is based on radar imagery and report information.
Spotter reported hail up to pennies in size at location.
Report received of a lot of golf ball sized hail falling at location.
Report received of hail up to pennies in size at location.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2023Every state in 2023This day in weather historyWarnings in Colorado, July 2023
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1120491, 1120493, 1120492, 1120494.