A late October trough brought significant weather impacts to portions of the western and central United States. The impressive trough was diagnosed in GOES-East water vapor imagery with features readily apparent (Fig 1). The upper jet extended south across the Pacific Northwest, rounded the base of the trough, and stretched northeast across the Great Basin and into the northern US plains. Exceptional shortwave energy near the base of the trough was digging south across northern California, and an associated cold front was racing south down the southern high plains. An overlay of GOES-16 Derived Motion Winds (DMWs) confirms the speed of the jet in areas where winds are available.
In California, extreme fire danger was observed as high pressure built in the wake of the potent shortwave, resulting in strong easterly surface winds and plummeting RH in the presence of very dry fuels. In northern California, rapid expansion and increase in temperature of the Kincade Fire was observed by GOES-West shortwave IR imagery during the overnight hours of the 26th into the early morning hours of the 27th (Fig 2).
Further east, the precise location of the cold front could be tracked as it pushed south across the high plains, with cold air pooling along the Colorado front range and southeast mountains (Fig 3). An overlay of MSAS 3-hr pressure changes and wind barbs shows an expected increasing pressure behind the IR-detected front, along with a shift of winds to a northerly direction.
With sunrise, the extensive shield of low clouds developing within the cold airmass in the wake of the cold front was observed in GOES-East visible satellite imagery (Fig 4). Pikes Peak and other mountain ranges are seen poking through the low cloud layer. Additionally, a multitude of cloud top gravity was are diagnosed atop the cloud layer.
Bill Line, NWS