UPDATE: The latest data continues to deepen the cold air behind early Saturday morning’s strong cold front (as discussed below). The airmass behind this front is going to be continental Canadian with H85 0°C line now projected to reach as far south as the I-20 corridor. This should promote widespread light freezing conditions across the northern half of the forecast area by Sunday morning. As a result, temperatures have been lowered Saturday into Monday. Temperatures may actually stay in the 40s for much of the day on Saturday with blustery north winds up to 35 mph and struggle to reach 50°F on Sunday. Clear skies and lighter winds will promote excellent radiational cooling potential Sunday morning with lows north of I-20 around the freezing mark, including DFW Airport. The colder spots may dip into the upper 20s. This is a good time to start winterizing your homes and taking precautions for sensitive vegetation. This cold snap will likely end the growing season for much of the area. There may be periods of light rain or drizzle on Saturday morning behind the front, but with the Gulf remaining shut off, precipitation looks rather meager at best and amounts will certainly be light.
The long range models continue to waffle back-and-fourth in the extended. There still seems to be signs of the possibility of an Arctic air intrusion around or just after the holidays . . .
High pressure will build in behind the departing low pressure and Pacific cold front today. The pressure gradient will tighten today from the building anti-cyclone and departing low pressure causing west southwest winds to gust to around 30 mph this afternoon, making for a windy day. The winds should decouple after sunset and allow temperatures to fall into the 40s everywhere overnight. Winds should stay up just enough to prohibit fog formation. Temperatures should remain seasonable through the end of the week with lows in the 40s and highs in the upper 60s to around 70°F, which is somewhat typical for this time of year (maybe a little warm on highs).
A stronger cold front is expected to arrive Saturday. Gulf moisture looks to remain cutoff from this front, so precipitation looks minimal. However, a very chilly airmass will advect in behind this front with H85 temps approaching 0°C. This will allow temperatures to plummet into the 30s area wide by Sunday and Monday mornings with highs only in the 50s. This will likely set the stage for the first frost of the season for the DFW Metroplex. Most likely, the cooler spots outside the urban heat island may even experience a light freeze. The average first freeze for DFW is November 22nd.
There are signs, and the ECMWF has been hinting at this for several runs, that the Arctic may open up just in time for the Thanksgiving holidays. The EPO (Eastern Pacific Oscillation) is projected to turn negative which is an indication of troughing across the central/eastern CONUS. The ECMWF continues to build an Arctic airmass in British Columbia and Northwest Territories seeding it from cross polar flow from Siberia. Then, spills this southward into the Plains and eastward over the holiday weekend or just after. The GFS has also shown some signs of this in the past several runs, however, the latest 0z run does not show this at all. This could be a very interesting thing to watch over the coming days . . .