Update - A sunny start to the week, but there's another ice storm in the making

Enjoy a good Monday, but folks on the eastern facing slopes of the Appalachians may have a dangerous situation on their hands Tuesday.

Updated Below (most recent 5:30pm)

Welcome to Monday. Another active week lies ahead.

But first thing's first: A nice day up front.

HPC - Surface Map - Monday

High pressure is still in control, and temperatures will still be seasonably mild in the sunshine. The elephant in the room however, is that next system coming in from the southern plains. As we discusses previously last week, this one has a similar feel to the last one we went through-- an overrunning storm that hits cold air that languishes at the surface. The immediate threat that comes to mind is for icing. If you notice in the tracking maps at the bottom of this post, winter storm watches are already up, and that's not for snowfall.

As these things go, our storm system approaches from the southwest and passes either right over us or to the west of us. Warm air is rushed up out ahead of the storm as well, meaning a lot of us get rain.

NAM - Tuesday Morning NAM - Tuesday Afternoon

Early Tuesday morning is when things get started. That low pressure system moves into the Tennessee Valley, and wind comes around the southeast to wrap around the system in counter-clockwise fashion (I've put the wind arrow on the left-hand map). At the same time, cold air is still entrenched into the valleys and not able to be scoured out by the warm air running over the top of it. On the above maps, the temperature at the 5000-foot level is indicated by the black lines. Solid is above freezing, dashed is below freezing. At first, there's enough cold air in place for some sleet (or heavy freezing rain), but later in the day (right-hand map) the layer of cold air gets whittled away until it's just ice and just in the deeper east-facing mountain slopes.

<tangent>--- About Freezing Rain ----

Here's another potentially confusing model product image that meteorologists use when storms like this approach. It's important that all sorts of things appear at the same time, because it's when all the variables line up properly that things happen.

Okay, so here's the image:

NAM - Cross-Sections - Lewisburg, WV - Tuesday Morning NAM - Cross-Sections - Lewisburg, WV - Tuesday Morning (my embellishment)

This image shows the cross-section of temperature and altitude for Lewisburg, WV at 7:00am on Tuesday. The temperature profile with altitude is indicated by the red line. Any time the red line crosses the vertical line marked "0" it is getting above or below freezing. Warmer temperatures are on the right. Looking at the right-hand image, you can get an idea why this map is so useful. Meteorologists can now get an idea where warm layers in the atmosphere exist, and how thick/strong they are. In this particular case, we've got a pretty strong warm layer about 5000-feet thick sitting ontop of a cold layer that is in the 20s (F). With this set-up (over Lewisburg), the result is either sleet or a really nasty case of freezing rain. Considering that some of the model outputs are pushing for a 1/2" of ice, unfortunately that the latter direction is what to lean in.


This is what the NAM model is coming up with for precipitation type for those same intervals:

NAM - Precipitation Type - Tuesday Morning NAM - Precipitation Type - Tuesday Afternoon

Beckley gets into this freezing rain mix, be careful out that way on Tuesday. Lewisburg is much more targeted though, so heading east from Beckley along I-64 could get downright treacherous Tuesday. Same could be said for those mountain valley roads right up through to Canaan Valley and I-68.

The rest of the week stays active (and interesting)

The first hints of a change can be seen on the precipitation type map above for Tuesday afternoon. Notice the appearance of snowfall (blue) in northern Indiana and southern Michigan. Colder air is getting wrapped back around the west side of the low as it moves up through the Ohio Valley. Eventually, it is progged by the models to stall out to our north, setting up a circulation that draws lake moisture into the tri-state area. For a long time:

GFS - Wednesday Morning GFS - Thursday Morning GFS - Friday Morning

This circulation, together with the lakes, will bring prolonged light precipitation to our area. Given the on-the-fence temperature profile, we can be going back and forth between occasional light rain and occasional light snow. My thought/concern from last week is also in the realm of possibility: That we see bouts of freezing drizzle too. The way this would happen is if we have snowable temperatures below freezing at the surface, but the clouds are too weak to develop the actual snowflakes. The end result is under-developed drizzle that will obviously also freeze when it makes it to the ground. This is something to keep in mind for the end of the week.


The week beyond...

6-10 Day Outlook - Temperature 6-10 Day Outlook - Precipitation

Looks like a nice El Nino cold swing, but unfortunately that southern stream jet isn't looking to moisture-rich. Not only that, the entire US isn't going looking at much precipitation. That's a bit rare for March. I wouldn't be surprised if this doesn't change (or ends up being wrong).

Update (5:30pm) - The National Weather Service has upgraded its advisories in the eastern West Virginia counties to Ice Storm Warnings and Winter Storm Warnings. On the warning map below Pocahontas and Randolph counties in WV aren't showing up with a warning (it has to do with the peculiar coding of the not-often-used Ice Storm Warning). A new blog post will come up tonight regarding the ice. Most of the effects will be east of our viewing area, but Richwood, WV and points east for travelers should be on notice that those roads won't be that great during the morning tomorrow.


Regional Radar/Satellite with Warnings Tracking

Accuweather Radar

From the Storm Prediction Center (below): Click For a Larger Image

Activity Overview Storm Outlook Watches Potential Watches Storm Reports
Temperatures HD Doppler Radar Estimated Rainfall Active Warnings
Current Temperatures HD Doppler Radar Estimated Rainfall Active NWS Warnings
Click For Larger Click For Interactive Radar Click For Larger Click For Larger

Have a great day everyone!


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