Stubborn pattern over the United States that has what cold is available in the west and warmth for the eastern half of the country. This pattern has been dominant for much of December and will continue through Christmas with near record heat in some places.

For those hoping to see some actual winter weather or temperatures this year for Christmas are going to be very disappointed. Temperatures well above normal will be the rule this week as with much of December 2015. In fact, December 2015 is in the running of being the all time hottest December on record for DFW. As has been the case this year, intense southern stream storm systems have brought copious amounts of rains to the area. It looks like the storm system we are watching post Christmas will be no different.

In the meantime, there a couple of smaller features to discuss in the short-term. Today, a weak cold front will push the soupier air and fog from this morning southeastward as it sweeps across the area. This will allow clouds to clear and temperatures to fall into the 40s overnight (still well above normal for this time of year). Tomorrow morning will likely be the coolest morning of the week. The radiational cooling setup tonight combined with light winds and lingering moisture will set the stage for the potential for fog tonight after midnight. Some of this fog could be dense and may take sometime Tuesday morning to burn off.

A weak short wave trough will dive out of the Rockies into the Central Plains Tuesday and rapidly intensify. This will draw the soupier air back over DFW by Tuesday afternoon, setting the stage for scattered convection from the I-35 corridor points eastward by early Tuesday evening. The official forecast will carry POPs at 20 percent to account for any storms. Any storms that form will have the potential to become strong to even severe as 1000 to 2000 J/Kg of CAPE can be realized by Tuesday evening across the area. Any severe storms would be capable of damaging winds and the threat of moderate to large hail. An isolated tornado threat cannot be entirely ruled out east of the Metroplex, but the tornado threat looks low. Storms will quickly move eastward as the shortwave lifts northeast away from the region.

In its wake, southwest flow aloft will dominate out ahead of potent storm system that moves onto the Pacific northwest. This system is expected to dive into the desert southwest and intensify while becoming partially closed off. The computer models diverge substantially in the handling of this system, but it looks like it will be our next big storm system post Christmas. Warm air advection showers will begin to break out across the area as early as Christmas Day afternoon. This system will have a good fetch of moisture to work with, given the long stretch of southerly flow ahead of it, bringing with it a potential for heavy rainfall as a rather strong cold front dives in from the north on Saturday. It is too soon to tell how much rain we will get, but it does look like at least enough to send us over the 60 inch mark at DFW for the year. This system will need to be watched closely for heavy rainfall leading to more flooding problems and if the precipitation shuts off before the significantly colder air arrives. Stay tuned for inevitable updates to this forecast as the week progresses.

12/9/2015 Current satellite image of next storm system and path.

After a good reprieve from the excessive rainfall over the Thanksgiving Holidays, rain will return to North Texas this weekend. Rain chances will be highest on Saturday evening into Saturday night. The greatest threat for flash flooding will be along and east of the I-35 corridor where the heaviest rains fell last time. Grounds are still saturated from the last event, and coupled with the dormant vegetation, flash flooding will be a real concern. Instability with this system will be small with high shear, thus a rogue strong to severe storm cannot be ruled out.

A warm air advection pattern will continue through Saturday as southwest flow aloft prevails across the area out ahead of the storm system. This will advect moisture and ridiculously warm temperatures into our area. In fact, they will be downright hot for December. Highs on Friday may flirt with the record high at DFW which is 80°F set in 1938 and 1996. This will be highly dependent on cloud cover and moisture, thus the dfwweather.org forecast has officially kept highs just shy of the record. Overnight lows will be well above the normal high for early December Friday night (in the low to mid 60s) which is about 59°F. These temperatures are nearly 30 degrees above normal for this time of year. A Pacific cold front will push across the area Saturday night and this will be the main focus for shower and thunderstorm development. Some lingering rain showers behind the front may be possible on Sunday, especially if the slower ECMWF scenario pans out. Otherwise, temperatures will return to more seasonable levels behind the front with lows in the 40s and highs in the 50s.

It is too early to forecast rain amounts with the weekend system, but early indications are that amounts will generally be around an inch or less. It must be stressed, we are not expecting anywhere close to the amounts received over Thanksgiving.

We will be watching another storm system taking shape for next week that may bring even more rain to the area.

DFW Weather forecasted rain amounts through Sunday 12/13/2015.

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 . . .