The main weather feature impacting the Nation through early next week will be a strong autumn frontal boundary responsible for separating record-breaking warmth in the Deep South and East from early season Arctic air dropping south across portions of the north-central United States.
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This front will be settling south and east with time and will drive an elongated axis of heavy showers and thunderstorms today from the Southern Plains through the Lower Mississippi Valley.
A focused area of heavy rain occuring this morning over parts of North Texas and near the Dallas-Fort Worth metro also experienced pockets of very heavy rainfall on Friday, which will create the potential for more widespread flash flooding.
Thus, a Moderate Risk (level 3/4) of Excessive Rainfall remains in effect today for these locations.
Gradually, these heavy rains will advance northeast into the Ohio Valley tonight and Sunday as multiple waves of low pressure advance northeastward along the front.
Locally a few inches of rain can be expected in vicinity of the front, and given the multiple rounds of heavy rain, scattered areas of flash flooding will be possible through the weekend.
A Slight Risk (level 2/4) of Excessive Rainfall has been issued through Sunday from central Texas to western Kentucky and Tennessse.
As the aforementioned front banks up against the Rockies and the Front Range, an upper trough will be digging across the Intermountain West today and ejecting east out into the High Plains on Sunday.
Heavy snowfall will impact the Central Rockies and Front Range with somewhat lighter amounts spreading across the adjacent High Plains.
Winter Storm Warnings have been issued for the mountainous terrain of western Colorado, where as much as 1 to 2 feet of snow is expected this weekend.
Winter Storm Warnings alos extend into the Front Range and Denver metropolitan area due to the potential for snowfall accumulations between 6 and 14 inches.
Lesser amounts up to as much as 4 to 6 inches can be expected from northeast Colorado and into the Nebraska Sandhills.
Additionally, light freezing rain/drizzle is possible on Sunday across the southern High Plains and Central Plains on Sunday as very cold surface temperatures surge southward within an area of showers located north of lingering frontal boundary.
This has led to the issuance of Winter Weather Advisories into parts of the Central Plains.
A strong area of high pressure nosing southward into the northern/central High Plains will produce plenty of cold air for the aforementioned snowfall, while also leading to single digit low temperatures across parts of Montana, Wyoming, and North Dakota.
A few daily low temperature records are not out of the question this morning.
This same area of strong high pressure will force a cold front passage all the way through the entire Great Basin and the Desert Southwest by the end of the weekend.
Cooler temperatures will arrive as a result, but as high pressure builds southward, much drier air along with strong, gusty winds will begin to impact California.
This will set up a Santa Ana wind event for southern California by Sunday, and will result in a developing critical threat of wildfire activity for the Transverse Ranges and the Los Angeles Basin.
Elsewhere, and opposite of the bitter cold in the north-central U.S., summer-like temperatures are in the forecast from the Tennessee Valley and Gulf Coast states to the Northeast this weekend.
Strong southerly flow ahead of the approaching cold front will create dry conditions and temperatures 10 to 30 degrees above late-October averages.
Afternoon highs are forecast to reach into the low-to-mid 80s for most locations and could break numerous daily high temperature records.
A quick reprieve back to colder weather though is expected across the Northeast and northern Mid-Atlantic on Sunday along with a likelihood for scattered areas of showers as the cold front crosses this region.
Meanwhile, temperatures across the Tennessee Valley and Southeast should remain very warm through Monday with highs here staying in the 80s ahead of the advancing cold front. ■