For those who are not familiar with these Monday Morning (aka "Mo Mo") blogs, I decided to put one out every Monday morning to highlight the upcoming weeks weather and a bit of the long range. This week is especially important because it's one of the busiest travel weeks of the year. Thanksgiving!
Short Range
The first few days of the week will feature dry weather but some pretty cold temperatures, especially in the morning. High's around the Tri-State area will be in the mid to upper 40's between today and Wednesday with low's in the 20's and low 30's.
A low pressure system developed off the coast yesterday. The baroclinic zone remained well offshore keeping precip out to sea. As the storm moved north into extreme eastern Canada, a trough sneaked in behind to settle over the northeast. Notable by winds shifting to the northwest allowing to transfer cold air from Canada into our area.
Here is a look at what the EURO is predicting for temps valid 7am Tuesday (left) and Wednesday (right) morning. Both images show temps in the upper 20's to low 30's, which is pretty cold for this time of year.
Thanksgiving Day
500mb Height Anomalies from the 12z EPS show an elongated ridge over the eastern CONUS. This promotes the southwest flow to take over and bring mild temps into our area, possibly getting into the 60's around NYC Metro! The very fast northern jet boots out the High Pressure that was there earlier in the week to our north which would have helped combat winds from turning to the south. This gives the deep anomalous trough over the west more power to raise heights over the east coast.
It is also looking like a dry week and Thanksgiving is expected over the eastern U.S. High Pressure is in control until we get to early Saturday morning. A weak cold front will come through bringing little to no rain while also taking temperatures back down to average.
December 1st Storm?
The EURO and GFS suggest there will be an east coast storm to track on December 1st. The question on everyone's mind of course is will there be snow associated with it? Let's check out the upper air pattern.
The Sub-Tropical Jet is once again looking to rear its head. Of course, that is not surprising given the strong El Nino we have going on over the Tropical Pacific. The above is the 12z EPS showing the ridge axis over west-central Canada and a weak trough over the east. The deep trough over the Aleutians is impressive but centered a little too far east. This disallows the PNA from going positive while shunning the Canadian ridge east. Right away you'll notice there is not a cold air source to work with. A lot of the cold that is over our area at this time is moderated or antecedent from pieces of energy that break off the Aleutian trough and travel east. As long as the ridge axis is over central Canada and the AO is positive, it will be difficult to get an arctic express connection from Siberia into the eastern U.S.
The GFS cuts the storm to our west while trying to transfer energy to the coast. Boundary layer temps warm up in this scenario which would promote rain for most across the northeast. The EURO keeps the 500mb vort far enough south that by the time a phase occurs the surface low is right on or just off the east coast. In this scenario, wintry weather has a chance to impact areas all the way to the coast. As the storm deepens, it pulls cold air to the coast and changes rain to a heavy wet snow. Dynamic cooling plays a big role in this event since we're not working with an arctic air mass.
At this time, I'm not a believer in the EURO scenario. I give more credence to the GFS trying to cut the primary low to our west. I also feel that if the storm did decide to take a EURO route, it has a good chance of going out to sea. The ridge axis is too far east for my liking and the flow over the east looks too fast for any storm to get organized. If the EURO maintains its position over the next couple of days then I will take it more seriously and look further into why it has a chance to be right.
Long Range
The top image is of the 12z EPS valid December 7th and the bottom is 12z GEFS for same time frame. We are looking pretty far out so take both these representations of 500mb heights with a grain of salt, but this looks pretty close to what I was thinking for December when I created my Winter Outlook. Initially this may look warm with all the reds and oranges, but the heights over the eastern U.S. are fairly neutral on both pieces of guidance. The warmest temp departures are in central and eastern Canada with slightly above normal across northern New England and upper Midwest. The Northeast and Mid-Atlantic are near normal. Like I said earlier in the blog, any cold air masses getting into the northeast are likely moderated because of the large Canadian ridge.
If we look at the latest run of the CFS American Seasonal model and what it had for December regarding 500mb heights anomalies, you cans see it's pretty close to what the GEFS and EPS are showing. Aleutian trough, Canadian ridge, +NAO, and biggest departures over central and eastern Canada.
With guidance in fair agreement, I am expecting December to go as planned with temps finishing above normal for the area when all is said and done. There is no wintry weather on the horizon anytime soon, though the December 1st threat bares watching still.
Next Monday, we'll look at the state of our Stratosphere, progression of El Nino, and an update to latest long range guidance. We'll also have a clear idea of what our sensible weather will be on December 1st.
Enjoy your week. I wish everyone a Happy Thanksgiving.
Take Care,
Frank
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