textproduct: Blacksburg

SYNOPSIS

Low pressure will move from the Gulf Coast to the North Carolina coast through Friday, bringing wintry precipitation to our area mainly in the form of snow. This low exits to the east by Friday night with high pressure building in for Saturday. Another front moving in from the west may bring a chance of precipitation late Sunday into Monday.

NEAR TERM /THROUGH FRIDAY/

As of 640 PM EST Thursday...

Key Messages:

1) Model trends are leaning toward some higher amounts along/northwest of the I-81 corridor, so a few locations could see 5 or 6 inches but low confidence on coverage of those amounts.

2) Winter Weather Advisory in effect tonight into Friday for the entire region.

High-res solutions have upped the amounts some especially in the corridor northwest of I-81 into southeast WV. Ensembles are leaning on the 3-5 inch range, but solutions like the HRRR and 3km NAM are hinting out 6+ inch amounts over portions of Southeast WV into the higher ridges of the Blue Ridge north of Roanoke. Looking at some winter parameters such frontogentical forcing and -EPV indicates potential for some banding, but overall, the strength/speed of this system does not paint a strong picture of mesoscale banding lasting long, so overall, though we believe there will be places that see 5-6"+, the majority of the area will remain in the 2-4" range. Nonetheless, a plowable snow for most. Further south into NC, some mix and slightly warmer temps aloft will limit totals, but given temps falling back into the 20s tonight, no changes to the advisory were made.

Timing still looks to be 9pm at the earliest in far SW VA, reaching the NC/southern VA Piedmont by 2-3am, with most having snow around midnight-1am, then ending between 7am-noon.

To summarize amounts, we are expecting mainly 2-4", with locally 5-6" along/north of of U.S. 460 and northwest of I-81 from Bluefield/Wytheville, north into the Shenandoah Valley, with potential 3-4" amounts in spots along the 460 corridor from Roanoke to Lynchburg. Along/south of US 58 in southern VA expecting 1-2" amounts. A light glaze of ice still possible in the NC mountains into far SW VA, just a few hundredths.

Previous discussion...

A low pressure system will bring in snowy conditions tonight into Friday morning. Recent model guidance suggests this system may arrive a little earlier than initially anticipated. Currently, the far western mountainous counties may start to receive light snow as early as 10PM. As the system moves east, isentropic lift starts to peak around midnight and light snowfall will take over the area. The snow will begin to move out around daybreak but may linger on for a few additional hours before precipitation chances drop towards zero by early Friday afternoon. Ensemble model guidance as increased the QPF expected which will translate into more snow amounts. For most of the region, between 2-4" are forecast to accumulate overnight with localized areas receiving up to 5-6". Counties in North Carolina and counties in Virginia bordering NC may receive the least amount of snow with only about 1-2". The reason for this is while the snow system makes its way through, a surface high pressure system to our northeast will begin to wedge in. This will reinforce cold air into the area. Due to the timing of this wedge and the snow arrival, areas in the Piedmont may receive rain at first which will then transition into snow.

Winds may pick up as the snow moves through, mostly for areas further west. Even a modest wind gust, however, will decrease visibility with the light snow. To reiterate from previous discussions, the early morning commute Friday will be undesirable given the snowy conditions.

Confidence in this forecast is high.

SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/

As of 1245 PM EST Thursday...

Key Messages:

1) Quieter weekend with below normal temperatures

2) Front on Sunday night/Monday morning will bring rain for most, some snow in mountains

Saturday will be mostly quiet with zonal upper flow and little to speak of in terms of synoptic features. Temperatures will drop well into the 20s each night. Daytime highs will warm back into the 40s for most, with Monday being cooler behind a front.

Sunday will feature a cold front introducing rain starting Sunday night. As temperatures drop with the frontal passage, upslope snow will take over for rain in the mountains, largely west of Roanoke. Piedmont and central VA regions will remain liquid in terms of p- type. Accumulation amounts will be light with this system, as there will not be sufficient moisture available for large QPF.

LONG TERM /MONDAY THROUGH THURSDAY/

As of 1245 PM EST Thursday...

Key Messages:

1) Quiet workweek bookended by a late week front

In high pressure behind Sunday's front, the remainder of the workweek will suppressed by a broad strong region of high pressure. Monday night will be the coldest immediately in the wake of the front, with temperatures for most of the forecast area dropping into the teens. Luckily there will be little wind to speak of, so we will likely avoid dangerous wind chills. Temperatures warm back to just below normal for the end of the week, as we look ahead to the next frontal system likely to impact us Friday. We have settled into a familiar frequency of frontal systems in winter of another every 3-4 days. Too early to make a call on whether snow will be included with the late week system, but it is December, so it wouldn't raise any eyebrows if frozen precipitation entered the conversation in the next day or two.

EXTENDED AVIATION OUTLOOK

Persistent low level cloud cover this weekend and another system early next week may keep all terminals sub-VFR for a while. It may not be until higher pressure moves in around mid-next week that skies become clear, but another potential winter system may return following it.

RNK WATCHES/WARNINGS/ADVISORIES

VA...Winter Weather Advisory until 1 PM EST Friday for VAZ007-009- 015. Winter Weather Advisory from midnight tonight to 7 PM EST Friday for VAZ010>014-016>020-022>024-032>035. Winter Weather Advisory from 1 AM to 7 PM EST Friday for VAZ043>047-058-059. NC...Winter Weather Advisory until 1 PM EST Friday for NCZ001-002- 018. Winter Weather Advisory from midnight tonight to 7 PM EST Friday for NCZ003>006-019-020. WV...Winter Weather Advisory from midnight tonight to 7 PM EST Friday for WVZ042>044-507-508.