Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 549 PM EST Mon Jan 30 2023 Valid 00Z Tue Jan 31 2023 - 00Z Fri Feb 03 2023 ...Significant and Long-Duration Ice Storm For Portions of Texas and Oklahoma through the Mid-South... ...West-Central Texas through the Mid-South... Days 1-3... While the general consensus of the models has trended drier for some areas, there remains a strong signal for a significant ice storm extending from west-central Texas through the Mid-South. An amplified upper trough/low is forecast to drop south along the Southern California Coast this evening before slowly drifting east along the U.S.-Mexico border on Tuesday and Wednesday. This will channel Pacific moisture into the region as a downstream ridge draws moisture north from the Gulf of Mexico. This deep moisture will be drawn into an area of increasing lift supported by right-entrance region upper jet forcing, low-amplitude mid-level energy, and low-to-mid level frontogenesis. An arctic airmass nosing south through the Plains and Mississippi Valley will maintain a large area of subfreezing temperatures from west-central Texas to the Mid-South through at least Tuesday. Overrunning precipitation associated with a weak mid-level wave is forecast to move east from the eastern Plains through the Mid-South tonight before a broader area begins to develop and spread east from central Texas to the Mid-South on Tuesday. Impactful ice accumulations are expected with these initial rounds, with WPC probabilities showing a long stretch of high probabilities for 0.10 inch or more of ice extending from central Texas through the Mid-South by late Tuesday. The highest probabilities extend from central Arkansas through western Tennessee and include the Little Rock and Memphis metros. Locally heavier amounts of 0.25 inch or more are possible across this area. Along the northern edge of the precipitation shield, the cold air air is expected to be deep enough to support accumulating sleet and light snow from portions of northern Arkansas into the Ohio Valley. As the upper trough in the Southwest continues to drift east, increasing moisture and lift will support the development of heavier precipitation farther west across Texas Tuesday night into Wednesday. This includes portions of the Rolling Plains, Concho Valley, and Hill Country. With this heavier precipitation expected to spread northeast, WPC guidance shows probabilities above 50 percent for ice accumulations of 0.25 inch or more extending from this area into North Texas late Tuesday to late Wednesday. High probabilities for 0.10 inch or more extend as far south as the Austin Metro. Along the northwest edge of the precipitation shield, cold air is expected to be deep enough to support accumulating sleet and some light snow. Meanwhile periods of light to moderate precipitation will continue to move east from Arkansas into the Tennessee Valley, with WPC guidance indicating additional ice accumulations of 0.10 inch or more are likely across the area. Periods of freezing rain are expected to continue into Wednesday night into early Thursday. However by late Thursday, drier conditions are expected to develop as the upper trough begins to phase with the northern stream and accelerate east across the region. By the end of the period however, storm total ice accumulations of 0.25 inch or more will likely be common across the region, with locally heavier amounts of 0.5 inch or more possible. Areas impacted by this event will likely include the Austin, Dallas-Fort Worth, Little Rock, and Memphis metros. Forecast confidence does remain limited in part by continued model spread with respect to the southern extent and persistence of the cold air, with daytime Wednesday the most uncertain period. WPC continued to prefer and lean toward the consistently colder NAM and Canadian Regional, which maintain the colder air longer into the period and bring the potential for significant ice accumulations farther to the south than the GFS and the EC. ...Southwest to the Colorado Rockies... Day 1... Deep southwesterly flow ahead of an amplified trough digging south along the coast of Southern California will continue to direct Pacific moisture across Southern California and through the Four Corners region. Some additional heavy snow amounts are possible across the higher elevations of the Southern California mountains, Mogollon Rim and the northern Arizona plateaus, and the western Colorado ranges tonight. The potential for heavy snow is expected to wane by tomorrow as the trough begins to slide east and moisture advection into the region is disrupted by a low closing off along the U.S.-Mexico border. Pereira ...Key Messages for Jan 30-Feb 1 Ice Storm... --Winter Storm and Ice Storm Warnings are now in effect for portions of the Southern Plains and Mid-South. --Several rounds of mixed precipitation, primarily in the form of freezing rain and/or sleet are expected through Wednesday. --Ice accumulations of a quarter to a half inch are likely, with locally heavier amounts possible. --Accumulating ice on roadways, especially bridges and overpasses, will cause hazardous to dangerous travel conditions. --Power outages and tree damage are possible.