Greetings everyone! Thanks for stopping by the blog today.
We've got a lot of different weather storylines to follow through the end of this week and the start of the next one, so let's take each in hand.
HPC - Surface Map - Thursday Night
There's a lot of pieces to this puzzle, and they'll all be participating. First, a strong storm system that brought a blizzard to the Northern Plains moves into Canada, but still extends its tentacles all the way down to the Gulf of Mexico. That generates a inflow of moisture that will be able to ride up along the front and cause plenty of rain. The blocking high to the east will stall the progress of this system, keeping it in town for a while and sparking multiple ripples of energy to ride up along within that moisture zone. Next, we've got the bone-chilling cold out to the far west that will be chipping away at the back end of this system, bringing a rude awakening of winter-type temperatures and even snow and ice that may well finish all of this off.
1. Unseasonable Warmth - All this should be is a warning sign that things are about to change. Each of the other big weather events we had in November was preceded by surges into the 60s and 70s. If you wake up in the morning and it's not raining yet (best shot of this is in the Kanawha Valley), you will be on borrowed time. Nevertheless, temperatures can even spike toward 70 before dropping back in the rain. It has been a good time to make preparations though, for the other weather impacts that are coming.
2. Flooding potential - Yeah. It's there.
HPC - Projected Rainfall - Through Monday Night
A steady fetch of moisture rides up from the Gulf of Mexico, paralleling the Appalachians for much of Thursday through Friday evening. After a short break on Saturday (which will feature sunshine, but chilly temperatures), we're right back into another pulse that takes us from Sunday right through Monday night. It is indeed a lot of water, though the long-form duration of the event should keep most rivers in their banks.
But here's the problem: Drainage flooding. As often said, 1" of water across an acre of land is more than 25,000 gallons of water. If there is poor flood-engineering afoot, or more importantly a plugged up culvert or storm drain (lots of leaves you know), that water can puddle up and pond quickly. I fully expect there to be some water issues with this event-- made worse in places with poor drainage. Though most rivers will swell higher than they've been in weeks, the threat of large rivers getting out of their banks should be muted because of the long-duration the rain will take to completely accumulate. It will be an umbrella affair for a while.
3. Opportunities for Ice and Snow - There are THREE such time windows for this through Tuesday.
Time #1 - Late Friday into early Saturday
As the precipitation continues steady on Friday, the colder air will be arriving from the west. It will be turning rain to snow on the back edge, and that transition will be working eastward while at the same time that moisture plume is heading out. Normally a temperature profile like the one on the left wouldn't be quite good enough to get flakes in our area, but there is enough energy at work to make it happen by way of 'dynamic cooling'... Consider the idea that all the flakes falling high in the sky will keep each other cool right to the ground, and will be able to overcome (or even modify) the ambient environment to suit it's needs. This is just like how a pile of ice cubes tossed out of a cooler on a summer day doesn't instantly melt, but takes a little while.
But anyway, this change from rain to heavy wet snow can be a sudden one, and travelers will not like it one bit. The good news is that accumulations locally will be on the low side, mainly under an inch if anything at all, but it will impact the Wayne-Bridgeport state championship game up in Wheeling. What a sight it would be for folks to see a soggy field replaced with snowflakes-- and what a miserable thing for the hardy people in the stands to endure. The real time to be on alert is the long, bleary-eyed drive back south through rain and wet snow. Be careful--for sure!
Time #2 - Early Sunday
GFS - Sunday Morning
Saturday itself should be labeled an "Intermission". Cold air remains in place, with sunshine cracking in for a spell. But our deformation zone gets active again by Sunday morning as another energy pulse rides up from the Gulf of Mexico. The problem here is that there will be a lingering chill around the region in the morning which causes warm air to ride up and over the cold underneath it (notice above the 850mb temperatures are above freezing and getting warmer-- the air below it will be colder). This cold will be most firmly entrenched in the eastern WV mountain valleys, where icing can be more of a threat. Overall, I believe this is a temporary issue as we should go quickly to rain on Sunday. But, church-goers may want to keep an eye on this because the potential impact lies with travelers around those early day hours. A cold rain is certainly easier to get around in compared to a freezing rain.
Time #3 - Tuesday
Can you believe it-- our deformation zone of unsettled weather is still overhead? Anyway, by this point we finally see the ending stages of it whereby the cold air sweeps in with more finality and shunts the remaining moisture up and out of here. Temperatures will be cold enough for snow by Tuesday morning, and the moisture then kicks out of here during the afternoon. However, a lake-effect set up also ensues, so that right now the picture is a coating or so for the river-cities/lowland areas, and what can be appreciably more in the eastern WV mountains. This is certainly tentative at this time, but the pattern has rung true over the years.
Now, taken together over the whole period, here's a good time-series of precipitation type I've tooled together that can also help put this bucketful of issues in context:
Greens are rain, Blues are snow, and the Reds are freezing rain/ice.
A lot to take in over the next several days. Be advised.
Have a great day everyone!