Good Sunday Evening. Dry high pressure off of the east coast is providing Easterly flow into the region. That easterly flow is accompanied by southeasterly and southerly flow aloft. That is a very good setup for our area to receive a lot of rain. Light rainfall is beginning to overspread the area from the South and West. Right now the dry air remains at the surface but the rain will overcome that pretty quick as we go through the night. Winds will be a little gusty in the NW Mountains overnight but nothing too tremendous. The lower elevations across the foothills should continue to see calm winds.
An upper level low is continuing to strengthen tonight as it slowly moves into the Southeast toward the Gulf Coast. A weak surface low pressure is also evident and it continues to deepen as well. High pressure moving into the Northeast will funnel cold air down the Eastern slopes of the Blue Ridge. A true wedge scenario will develop as moisture overruns and falls into the shallow cold pool of air. Temps will fall back into the mid 50’s overnight and remain there through Monday. There is a big temperature gradient about 5000ft aloft and that will work to even further enhance rainfall toward daybreak Monday.
The highest rainfall rates appear to be over two separate areas....
The first is obvious and are the areas outlined by the Flood Watch. The counties of Burke, Caldwell, McDowell, and Rutherford look to receive 2-4 inches of rain. The upslope area of those counties say from Old Fort, North Cove, Little Switzerland, Lake James, Oak Hill, Jonas Ridge, Collettsville, Roseboro, Globe, Patterson, and The Yadkin River Valley could see totals up toward 5 inches. The good thing is that these totals are over a 48 hour period and not all in 24 hours. The main concern is the possibility of main stem river flooding along the Catawba, Linville, John’s and Yadkin Rivers. While widespread flash flooding isn’t expected I can’t rule out some localized issues developing along the Blue Ridge. Elsewhere across our Eastern counties generally 1-3 inches appears likely.
The second area of heaviest rain appears to be along the coastal areas of South Carolina and Southeast North Carolina. Those high totals there come from convection Monday which raises a few questions as to how much moisture is robbed before being transported up into our area. Although that appears possible the overall forecast totals above look in good shape. Below is the Weather Predictions Centers 48 hour rainfall forecast ending at 8pm Tuesday. The bulk of the rainfall should fall tonight, Monday, and Monday Night. Tuesday details are below the graphic.
Tuesday is going to be an interesting weather day and a day where the forecast resembles a very low confidence. The bulk of the rain should be lifting out of the area to the Northeast by Tuesday Morning. Left behind likely will be fog and low level drizzle as the Cold Air Damming (CAD) event remains in place. As we go through the day on Tuesday it appears the CAD should begin to break down allowing for some sun to pop at some point. At the same time the CAD is breaking down the upper low to our Southwest will be moving Northeast into the area. Long term models differ greatly from the near term models with the placement of the triple point. The near term NAM moves this low up into the mountains and Foothills while the long term GFS and Euro take the low from West to East across the Upstate of SC. The two tracks have very different outcomes. Ahead of this low, depending on how quick the CAD breaks down, there could be some heating and a huge surface temperature gradient. So along and east of this low, thunderstorms could errupt and train over the same areas time and time again. That would create a flash flood threat in the areas affected. Right now there is low confidence as to where this would develop. It could be from the lowlands of SC or it could be across the Upstate and Foothills. Just will have to narrow down that forecast tomorrow. High temperatures are a very tough call. Right now most of the area should remain in the low 60’s Tuesday. Cleveland and Lincoln could jump into the mid and upper 60’s if clouds thin out quick enough there.
Either way by Wednesday the low is lifting away from our area. In turn it will dig a cold front into the area which would give the chance of a few showers and mostly cloudy skies through the day. Temps should be able to rebound into the 60’s ahead of this front.
This front gets hung up across the area keeping our weather pattern very unsettled. We will keep scattered showers in the forecast through Saturday atleast. Not everyday will be a washout though as showers look more scattered than widespread right now.