Blizzard of 93

Wow, wow, wow at the potential the 0z runs are showing for the 22/23 !!! This is trending into a possible very special couple of days of Winter weather right before Christmas!

What’s your current thinking on precip type & amounts for your area & the LSV?

I think rates will play a good part in precip type. When it gets heavy, hopefully we flip to snow for awhile.

That’s one heck of a crazy cutoff! if this somehow played out, my house in Marysville would have about 5 inches of snow, while my office in northern Harrisburg would have barely 1 inch.

Yes! It’s going to be interesting to see how it plays out tomorrow. Hopefully we all get a good period of wintry weather tomorrow.

Temps at the onset will not be an issue for us tomorrow. Precip type in any one location especially for the LSV will be determined by the final track of the developing coastal low in NC.

Lots of options on the table for Christmas Eve Eve. The trend is our friend on the Op models & ensembles today.

30 with dew point of 19 currently in Marysville. Let’s get MDT on the board tomorrow more than a T that is on the books right now. Good chance of at least a few tenths of slop to record, but I’m hoping to get the first inch of the year for MDT. If the 18z HRRR or 18z GFS are right, then maybe MDT can score a little more?

19 for the low in Marysville this morning.

Winter Weather Advisory URGENT - WINTER WEATHER MESSAGE National Weather Service State College PA 417 AM EST Wed Dec 14 2022 PAZ036-056-057-059-063>066-150000- /O.NEW.KCTP.WW.Y.0026.221215T0600Z-221216T0000Z/ Franklin-Perry-Dauphin-Lebanon-Cumberland-Adams-York-Lancaster- Including the cities of Chambersburg, Newport, Harrisburg, Hershey, Lebanon, Carlisle, Gettysburg, York, and Lancaster 417 AM EST Wed Dec 14 2022 ...WINTER WEATHER ADVISORY IN EFFECT FROM 1 AM TO 7 PM EST THURSDAY... * WHAT...Mixed precipitation expected. Total snow and sleet accumulations of 1 to 3 inches and ice accumulations of up to one tenth of an inch. Winds gusting as high as 35 mph. * WHERE...Portions of central Pennsylvania. * WHEN...From 1 AM to 7 PM EST Thursday. * IMPACTS...Plan on slippery road conditions. The hazardous conditions could impact the morning and evening commute. * ADDITIONAL DETAILS...A mix of snow, sleet, and freezing rain will move in to the area from west to east Thursday morning. This is expected to last several hours before an eventual change to rain occurs from south to north by the late afternoon into the evening.

The 0z GFS gets Advisory level snow to most of us north of the turnpike in the LSV. Warning level snow for the mid & upper Susquehanna Valley this run.

The 0z GFS still for Thursday is advertising icy mix to snow for most of us and then the rain/snow line sets up north of the turnpike by Thursday night.

I agree…I’m thinking they issue it very early tomorrow.

Yes, the Harrisburg area is right on the line. I would not be surprised to see either of the scenarios that you mentioned.

The 12z Canadian snow map for the 23rd is super impressive and still going at the end of the run… All I want for Christmas …..

Please just once let the 12z Canadian be right in the long range & bring a Christmas blizzard!

6z Euro snow map.

Decent agreement on the 6z Euro and GFS. 6z Euro takes a similar path up until the low reaches the DelMarVa region. Same theme on precip with icy mix to start then snow for most for awhile and then the rain/snow line sets up around I-81 until the storm passes our latitude.

Here is the 6z GFS snow map through Friday.

The 6z GFS still has icy mix to snow then rain for areas south & east of I-81.

Great discussion from CTP this evening, ”Clouds Wed evening steadily lower/thicken-up late Wed night. Precip may arrive in the Laurel Highlands as early as midnight Wed night, and push northeastward towards the I-99 and I-80 corridor by sunrise Thu. Nearly all model guidance has a nose of warm air (+5C) at about 4-5 kft during the onset of precip, maximized over Somerset county. This will likely result in freezing rain for Somerset and Cambria counties during the morning Thu. Our preliminary freezing rain totals call for up to 0.25 inch of ice in the higher terrain of Somerset and Cambria Counties. Freezing rain impacts could be exacerbated by strong southeasterly winds, sustained 15-20 mph with gusts 30-40 mph. Strong winds and freezing rain may result in tree and powerline damage. As precip continues to overspread central PA during the daylight hours Thu, it will push into colder air. Although max wetbulbs aloft may be above freezing at the onset of precip, evaporative and dynamic cooling should bring the temp and td below freezing as the heaviest precip develops. Model guidance suggests the period from about 15z Thu - 00z Fri Thu will feature deep isentropic ascent and a fully saturated troposphere, with substantial upward motion in the DGZ aided by frontogenesis between 700-500 hPa. Our preliminary snowfall forecast calls for 4-6 inches of snow accumulation from AOO northeastward towards Potter and Tioga counties during this period of time. Gusty winds could result in reduced visby during moderate or heavy snow. After 00z Thu, the forecast becomes more uncertain. Warm air will advect northward, likely bringing the rain-snow line towards or even north of I-80. A dry slot aloft will significantly reduce the depth of the saturated layer, potentially resulting in the loss of ice within the clouds for a portion of the CWA. This part of the forecast depends largely on how quickly a secondary coastal low can develop - a stronger coastal low developing more quickly along the Mid Atlantic coast can draw in colder air to and more moisture, resulting in more snow accumulation Thu night into Fri. Additional snow accumulations during this period are most likely in our northeastern zones. Precip type, storm track, and storm intensity are still complicating factors that contribute to uncertainty at this time. We will continue to provide updates over the next few days as the system approaches and the forecast becomes more certain.”

CTP is starting to ramp up the Thursday potential… A potentially significant winter storm will brew over the central CONUS and spread into Pennsylvania on Thursday, lasting into Friday.

The 18z Euro ensemble snow map also increased snow amounts for the LSV this run.

The 18z Euro ensemble also improved for the LSV & CTP in general. The mean low tracks from eastern NC/VA border to the DelMarVa coast near OCMD to near Atlantic City, NJ.

We are going to be doing a lot of tracking between now & the holidays…buckle up!