A low pressure system brought cold temperatures aloft in Southeast Arizona, causing a cold core funnel cloud to form over Nogales.
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The episode as NWS TWC wrote it up.
A low pressure system brought cold temperatures aloft in Southeast Arizona, causing a cold core funnel cloud to form over Nogales.
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 Tucson, AZ wrote its last area forecast discussion before the first event at Dec 6, 2:23 PM MST, 2 hours 17 minutes earlier.
Area Forecast Discussion National Weather Service Tucson AZ 223 PM MST Fri Dec 6 2024 .SYNOPSIS... Isolated showers will diminish this evening. Drier conditions this weekend with near to above normal temperatures. Coilder temperatures are expected Tuesday and Wednesday, along with breezy conditions. There is potential that Tucson sees its first freeze of the season by Wednesday morning. && .DISCUSSION... A closed upper level low continues to spin over southern Arizona this afternoon. 14Z NUCAPS soundings depicted around 500 J/kg of MUCAPE across the forecast area, which combined with the cyclonic flow aloft and modest moisture profile has allowed for isolated shallow convection to develop today. As of 2030Z, more (relatively) robust convective towers have developed in the Santa Cruz county area, which sits under the center of the upper level low. Otherwise the current satellite picture shows very isolated development across the remainder of southeastern Arizona. Under more vigorous convection, lightning and small hail will be possible. Otherwise just very light rain or high elevation snow will be the main result of today's activity, as precipitable water under a half an inch is unsupportive of more mature convection. Going forward, the upper low should exit east as it becomes embedded in the northern stream flow. This northern stream will be diving south as a broud upper level trough deepens across the CONUS. Through Monday, near to above normal temperatures will continue across southeastern Arizona. Then the troughing arrives Tuesday along with a diving wave from the northwest. As this wave skirts southeastern Arizona to the northeast, the forecast remains mainly dry. Colder temperatures and breezy winds will likely accompany the wave, with potentially freezing morning lows in the Tucson area Wednesday morning. Sub-freezing temperature probability remains uncertain as the trajectory of the upper level wave doesn't promote confidence in truly penetrating cold air advection that brings freezing temperatures into Tucson. Current NBM probabilities of below freezing Wednesday morning lows remain in the 20-50 percent range, with deterministic forecast lows in the 32-36 degree range across the metro (depending on location/elevation). Well below freezing temperatures are more likely in typically colder locations to the east. Temperatures will likely moderate Wednesday onwards following this wave passage, with the CPC temperature outlook leaning above normal late next week. && .AVIATION... FEW-OVC clouds at 8-10k ft AGL from Tucson eastward thru 07/12Z when clouds decrease in coverage to SKC-FEW for the rest of the forecast period. Isolated showers possible areas Tucson east and southward this afternoon and evening. Winds generally easterly 10-18 kts, with gusts to 25 kts thru 07/00Z when winds decrease to 5-10 kts overnight. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER... A drying trend is expected into early next week. Minimum relative humidity values rise from 20 to 35 percent in the lower elevations Saturday to 15 to 20 percent Monday, then 10 to 15 percent Tuesday. High elevation humidity falls from 30 to 45 percent Saturday to 15 to 25 percent Tuesday. Winds should increase early next week, especially Tuesday and Wednesday as a dry cold front crosses the region. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && Public...Edwards Aviation...Tetrault Fire Weather....Edwards Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
The Tucson radar (KEMX), 65 km away, was scanning. The volume nearest the first event began at 23:41 UTC.
1 funnel cloud. Local standard time, as filed.
A trained spotter reported a weak funnel cloud that passed overhead Nogales, Arizona.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2024Every state in 2024This day in weather historyWarnings in Arizona, December 2024
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: 1229858.