|Dew Point:||22.0°F (-5.6°C)|
|Wind:||From the West at 4.0 MPH Gusting to 11.0 MPH|
|Wind Chill:||18°F (-8°C)|
|Sea Level Pressure:||30.14" (1020.5 mb)|
... High pressure spreads back over our region from the west and then moves off the East Coast on Thursday. Another significant low pressure system will develop to our west and bring more widespread precipitation to the region by the end of the work week and into the weekend.
NEAR TERM /THROUGH TUESDAY/... As of 1015 PM: A 500mb shortwave trough traversing the area continues to drive an area of light rain and/or drizzle across the lower Piedmont of GA/SC. The deep moisture will be driven south with time as drier high pressure expands from the Mississippi Valley across the southern Appalachians. Updated PoPs are lower as much of the returns on radar are not reported as reaching the ground. Temps remain several degrees above freezing where this precip is occurring. Significant cooling is not expected there until cloud cover is forced out late tonight. Profiles suggest that some snow may mix in where temps are coldest, but no direct wintry impacts are expected from the precip. However, this will keep roads wet and areas of black ice are thus expected wherever temps fall below freezing late tonight. The extent will be somewhat limited with temps not staying below freezing for very long before they warm again after daybreak. For now we will maintain a mention of the threat in a Special Weather Statement.
Further north, though temps are largely still above freezing, cloud cover is beginning to break up. Dewpoints are already several degrees lower than those in the precip area. On these notes, over the northern zones temps should begin to fall sooner and faster. With several inches or more of snow cover still remaining min temps will be particularly cold, though hi-res models seem to continue to struggle to adequately resolve them. Temps eventually are expected to fall into the mid 20s. With such low morning temps...it will take a while before sfc readings rise abv freezing...making for an extended period of black ice into mid to late morning...while the nrn NC mtns will likely remain below freezing until the early afternoon. A winter weather advisory remains in effect for the northern two-thirds of the CWFA for black ice. While prog profiles look unfavorable to maintain a deep fog layer, dewpoint depressions will shrink, permitting some patchy fog to form. The dense fog depicted on e.g. the HRRR still seems overdone, possibly resulting from the aforementioned unrealistic surface cooling over the snow--HRRR min temp fcst at KCLT is 19 tonight. At any rate, wherever sfc temps fall below freezing, any fog would be freezing fog, possibly making surfaces slippery where not otherwise icy.
Another cold day on tap for Tue...yet it will be warmer than Monday was. Skies will clear out...but with temps beginning the day so cold and a reinforcing cP high building in...maxes will be held abt 10 degrees below normal.
SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... As of 200 PM EST Monday: The short term begins at 00z Wednesday with NW flow aloft in the wake of the exiting wave, and weak ridging beginning to build in from the west. Surface high pressure over the northern Gulf Coast will work its way east, but troughing will remain in the Piedmont and adjacent foothills, resulting in another very cold night Tuesday night and chilly day on Wednesday. A shortwave embedded in the flow will pass to our north Wednesday night and Thursday, but should remain mostly dry, though cannot rule out some isolated sprinkles or flurries especially the upslope areas of the SW mountains. As the shortwave passes, weak ridging will begin to build in ahead of a trough deepening down the Plains. Southwest flow aloft will begin bringing a little more WAA into the area toward the end of the short term, but with warm frontal precip ahead this way of the deepening surface low over the Red River (of the south) Valley.
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... As of 215 PM EST Monday: As we move into the extended, precip will be overspreading the area from the west as the upper low cuts off and digs in to the Lower MS Valley. Significant gulf moisture will lift into the Deep South as the surface low occludes and the cold front starts pushing east. Meanwhile, high pressure will move off the Atlantic to our north, and as the precipitation starts falling into the low-level dry layer, insitu damming will develop. Luckily the incoming moisture will keep overnight lows Thursday night a little warmer, because with a substantial warm nose in the low-level WAA, if surface temperatures drop below freezing, could see some freezing rain at onset. For now, since the warm nose is less substantial further north, have kept ptype as a rain/snow mix, but will need to continue reevaluating. Anything that falls will be brief as temperatures warm during the day on Friday, though as a note there is definite bust potential with highs depending on the strength of the high. The insitu damming does look like it will keep us pretty stable, and although the system is highly dynamic with an impressive LLJ and deep-layer shear, instability is minimal to nonexistent. Have continued trend of no thunder in the grids for now. Other concern is the QPF, and we could see some storm total amounts upwards of 3-4" Friday through Saturday, maximized (of course) along the escarpment and especially the upslope areas of the SW mountains. Still some disagreement in the track of the upper low as it passes near (overhead or just to our north), but we should get some flavor of NW flow snow across the mountains on the back edge, some accumulation would be possible. Good thing though is that temperatures trend closer to normal through the weekend.