Tuesday December 13 2022

If you have been following my updates, then you may know that I am careful to NOT use the word ‘storm’ unless I believe it deserves it. For now, I expect an impact event for colder inland metro areas and A Winter Storm Watch has been issued for some mountainous regions.  

The good news is that we continue to see agreement and thus high confidence in this starting icy west of I-95, and parts of Baltimore. The good news is the anticipation before sunrise will help make the call for schools, but not for travelers.  However, salting should help the I-95 vicinity west.

I will continue to compare the three main models, but I am leaning toward the Canadian GEM product as the baseline. This has a history of performing best in arctic air patterns. We are not there yet, but I want to give it a chance.

What may follow our icy Thursday morning and chilly rain will be colder air and energy in the jet stream. We could see break out flurries or snow showers this weekend. Then, NEXT WEEK there is a signal for a larger storm just before Christmas. I will show it all below. 

Winter Storm Watch

This is all The National Weather Service has issued so far. I expect we will see ‘advisories’ into central Maryland and more alerts through much of Pennsylvania. 

This includes I-81 through Virginia and westward into the mountains where ice will be a big impact.

I can’t issue weather advisories, I can just show what NWS publishes and make suggestions. The updates may happen tonight, but should almost certainly arrive Wednesday.

Model Comparison 

Thursday Morning: 

We still see mostly freezing rain, perhaps some sleet beginning across the central Maryland region between 4 AM and 6 AM on the GFS, Canadian, and European Models.

Thursday Afternoon

• The GFS remains colder with a storm track farther south. This shows SNOW through metro Baltimore. 
• The Canadian retreats the freezing rain to the normal colder suburbs and into Southern PA. 
• The European model is warmest with rain in central Maryland, but does show a slushy snow mix into Lancaster County, PA. 
• The mountains remain with a heavy ice storm!

Thursday Evening

With the Low Pressure now on the local map, we can see the influence of the warming to rain, but it will be heavy!

The GFS and European do keep some hint of snow very close by the MD/PA line.

Model Animations

Comparing the colder GFS to the Canadian Model which is mostly freezing rain.  

GFS Model 

4 AM THU to 1 PM FRI

In addition to the suspicious snow midday in central Maryland, this keeps the cold air close enough to end with snow by the MD/PA line Friday.  I would not expect stickage from this.

Canadian GEM

4 AM THU to 10 AM SAT

I wanted to show more of the ice, this is the model I am going with… It also is more in line with my suggestion of flurries or snow showers on Saturday. More detail on that below.

Key Timeframes 

10 AM Thursday 

I chose this because of what we start with before sunrise, and we see a continuation here (the GFS does bring in snow).

I drew the WHITE LINE to follow the freezing temperature line.  This is the region I have believe will see some icing early, then a slow improvement through mid day.

10 AM Temperatures 

I’ve continued to see the same general FREEZING LINE similar to climatology for this time of year. Near I-95 and the Bay there is a warming influence from the water. The more likely icy zones will be farther inland.

My First Call May (revisited)

This is what I posted last night and it still fits with this product. 

4 PM

Most of central Maryland should turn to steady moderate to heavy rain at this time, while the ice storm continues in the mountains.

Just north into PA there may be slushy snow. This is where the cold air will be stubborn to move out.

10 PM

Most of our region should be over to all rain at this point, and possibly ending by midnight or at least overnight. If we get showers Friday morning, it would be from wrap around with the Low far north into New England. 

How Much Rain?

It may seem like quite a bit with the Canadian possibly over doing the Over 2 inch swath. But I would be content to say over 1 inch is still an impressive storm total for the general area. Note, southern PA is actually in a rain deficit for the year.

GFS Model Total (all stuff combined)

A large area over 1 inch, with the 2 inch bullseye over Kent Island/Chesapeake Bay.

Canadian GEM Model Total (all stuff combined)

This has a much larger 2 inch total through southern Pennsylvania and much of Maryland. This may be a little on the high side.

Weekend Flurries or Snow Showers?

Here is the Vorticity/Spin at 500mb (around 18,000 Ft). This shows the energy aloft with two impulses over the weekend. 

Saturday

This is a broader base wave in a jet streak. It will keep clouds around, and may spit flurries or snow showers. 

Sunday 

This is a weak Vort Max that may ignite some spotty showers with cold enough air to produce flakes without much substance. Just ambiance. 

Looking To Christmas Week:

The Canadian May MEAN IT!

Check out this Jet Stream Plot from the Canadian Model for Thursday Morning. I could not resist that we have to Face the reality of the arctic air on the move…

Jet Stream Animation 

Thu Dec 25 to Fri Dec 23

See the end frame below for my thoughts as this Deep Trough digs across the Eastern US and a Core Low is poised over central Maryland.

Friday Morning December 23

I do NOT make promises this far out, but it was hard to resist this view. It is subject to change, but if this verifies it would spell a major east coast winter storm. Definitely something to keep watching.

Faith in the Flakes

I will have my regular morning forecast by 6:30 AM

EXPLORE MORE

See the Regional NWS Maps

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It began with my son in 2009

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Faith in the Flakes Gear

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Click to see more and ‘Book’ a visit to your school

My Winter Outlook: Not A Typical La Niña!

I see many factors to support colder influence with multiple systems. Early and later in winter. Check it out.

Winter Outlook 2023 For Snow Not Typical La Niña Plus Polar Vortex Disruption

Also See The Winter Outlook Series:

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Winter Outlook 2023 Early Look At Snow From Two Farmers Almanacs

Triple Dip La Niña Winter

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CONNECTION TO WINTER?

If you want a snowy winter, this is what you might want to look for in the rest of the tropical season. (You might be seeing a lot of commercial snow removal people out this Winter).

Record August For No Named Tropical Storms: Closer Look At Snow Following

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Persimmon Seeds

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Click to see Top 20 and MORE

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