MID ATLANTIC NY PA NJ DE MD DC MID ATLANTIC NY PA NJ DE MD DC

JAN 9 12:34PM - Monday Storm Thread UPDATED

Discussion started by jeffro 3 years ago

UPDATED JAN 10 - 2:30P

Good Afternoon All!

So the NAM is trending the way the CMC was trending yesterday - warmer.  Let's look at why the significant ice may not be as bad if the NAM solution is truth come Monday around 2AM.

This storm will still start out as ice/sleet for SE PA but will change to rain much faster than anticipated.

6AM Monday Morning:

nam mslp pcpn frzn us 15

 

If you recall, the most important factor in the type of precip would be dependent on the placement of the HP over the Upper MidWest.  Well...look at where it is modeled to be....in North Dakota.  That is too far north for the intense cold of that high to push our way.  Again, the Northern Stream being modeled to be much slower than the Southern Stream.

Let's take a look at the winds at the 850mb level as well.

nam mslp uv850 us 17

As I mentioned yesterday, because the HP is so far north, the winds are carring the warmer air up from the SW instead of the cold winds from the HP in the NW.

As always going to be the case, the temps at the 500mb level are quite warm which is why this was going to be an ice/sleet event in the first place:

nam z500 mslp us 17

 

All of this equals a start of sleet/ice but a quick change over to rain for SE PA.  Anyone south of PA, will be rain the whole time.

NOW....this is all based on modeling.  With how cold it has been with a +AO (its freaking cold outside today!!) and the way things have over performed lately, I am not so sold on the NAM solution right now.  As some others have mentioned, it is very difficult to make decisions thus far this winter and with the crazy way the models are behaving.  Things can certainly still change and there is still 36 hours before game time.

Hope y'all are having a great Saturday!

 

(Jan 9)

Hello Everyone!

So all the models are on board for Monday.  All are showing sleet/ice for SEPA and into SNJ.  Where the strong HP over the plains ends up will largely determine what the precip type is for Monday AM and then into the afternoon and evening.  We are at the point where we can start to consider the NAM as well.

The CMC has been showing the colder solution thus far but the 12Z GFS just came in a touch colder than the previous run.

gfs namer 075 850 temp mslp precip

 

AS an example of how different things can be based on the location of the HP in the upper MidWest, look at these two images from Hour 72 of the 12Z runs of the GFS and the CMC:

GFS:

gfs mslp pwat us 13

 

And then the CMC

gem mslp pwat us 13

 

Look at the direction of the winds and how in the GFS image you can see that the winds are delivering cold air from the HP and the winds in the CMC image are delivering warm air from the SouthWest.  Look at the subtle difference in the location of the HP.  We are talking a VERY subtle difference.

Comment away!

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Alicia979
Alicia979
This was in response to. dt's post on the euro weeklies
3 years ago
Snow1Md
Snow1Md
On the Monday event whats it looking like for Frederick,Md. Thanks
3 years ago
Brandon5
Brandon5
Well said Freeze.
3 years ago
FreezeMizer
FreezeMizer
With multiple and fairly close events, it's easy to get lost in the details.

First up is the Monday event. Will put out a detailed analysis blog on that soon. It's very interesting and will challenge the nowcasting skills.

Anyone looking past late next week may not be seeing the forest through the trees. Yes - pragmatic answer is a miss, and that's reasonable. But take a step back and see how it has unfolded over the last few days. E.g., GFS. had a nice coastal opportunity. (as did Euro) Then it went to a complete disaster shearing the hell out out everything and throwing it towards nowhere land. (and remember the crazy runs of the parallel with a coastal going backwards, south and then OTS). Recently (00Z last night) the GFS has come back with some semblance of a coastal, albeit, the coast is now considered the continental shelf....

Warmer than normal Atlantic temps, married with warmer than normal pac temps. There is almost too much to digest compared to other years.

Point being - we've seen the models all behave strangely more than 5 days out. We have a amped pattern with a lot of interactions and no real dominant factor......
3 years ago
jeffro
jeffro
There is also something else that really has things wonky. The AO has been at about a +3 and it has been incredibly cold. That really should not be the case. Monday it will be about a +2 and the cold retreats and the Southern Stream wins? Just wonky, I tell you.
3 years ago
TeleConnectSnow
TeleConnectSnow
different storm armando
3 years ago
LoveDelawareSnow
LoveDelawareSnow
If anyone on here acknowledges the troll..I am out of here. So over it.
3 years ago
PhilsPhan1
PhilsPhan1
Removed
3 years ago
TeleConnectSnow
TeleConnectSnow
PLEASE GUYS!
NO ONE ON THIS SITE ANSWER ANY OF CHARLES/PHILSFAN questions. He doesn't deserve the insight.
3 years ago
PhilsPhan1
PhilsPhan1
Removed
3 years ago
TeleConnectSnow
TeleConnectSnow
umm 12/20 Armando, where the GFS owned the EURO. It looks EXACTLY like this storm with the way the EURO held out, but now is slowing fading away OTS.

This storm is not a hit in my opinion at this stage anymore. I busted big time with it.
3 years ago
PhilsPhan1
PhilsPhan1
Removed
3 years ago
TeleConnectSnow
TeleConnectSnow
I'll tell ya what guys, the GFS is gaining respect from me lately. It's schooled the EURO so called "King" with all the big storms so far, when the EURO held on, the GFS dropped it, and the EURO later followed.

Anyways,
Charles, winters over according to you, so why do you care if its ice or rain. Please leave the site.
3 years ago
jeffro
jeffro
Jonathan123 At this very moment....Yes.
3 years ago
PhilsPhan1
PhilsPhan1
Removed
3 years ago
Legs
Legs
Great! Thanks for the explanation guys! Always trying to understand what fuels the beast!! LOL I wish I had more time to spend on it for sure! Glad I have very good sources to go to for explanations and insights!
3 years ago
Ksiegel35
Ksiegel35
Does this look like rain for Long Island?
3 years ago
jeffro
jeffro
What I just added to my post explains a little of why the CMC just had a warmer solution.
3 years ago
jeffro
jeffro
LEGS - I'm going to let Armando field that one. But you are on the right track.
3 years ago
Legs
Legs
Hey Guys, what is it in the modeling system that makes them differ so much in their solutions? Are they programmed to only read certain types of information at certain atmospheric levels and what range they get their best estimations? I'm just curious. Thanks jeffro/Armando
3 years ago
weather_andrew
weather_andrew
Thanks Armando. And yes jeffro I agree, certainly will be a case of timing of the two separate pieces. All this week the weather news has been the cold, so who is to say it wont continue to be!
3 years ago
jeffro
jeffro
This will be a northern/southern race. The systems from this past Monday and today also inform my gut that the models are underestimating the powerful cold to our NW.
3 years ago
weather_andrew
weather_andrew
Hey all, thanks for the updates on this storm. Hate to see ice in the forecast, too dangerous for my liking. Any knowledge of possible scenarios for the lehigh valley? Any chance of accumulating snow?
3 years ago
jeffro
jeffro
Another thing that is making me think about how cold it will truly be at the 850mb level is the direction the winds are coming from. There is clearly a change in the wind direction as you compare MD/DC/DE to OH into PA. Closer to the coast, the winds are coming from the warmer air. OH into PA the winds are coming from the source of cold air - the HP in the upper MidWest.
3 years ago
LoveDelawareSnow
LoveDelawareSnow
Understandable jeffro, no worries, thanks!!! I did notice that my area is in the pink shading on the map you posted; however, I know that can all change.
3 years ago
jeffro
jeffro
LoveDelawareSnow I am not comfortable making any sort of call yet. My gut tells me that you will most likely be in the rain - BUT - it has been so cold and those HPs in the midwest have been so strong that the models maybe underestimating how cold it will be Monday AM. If that is the case, you may be in the ice as well. Tomorrow night 00z should make things more solid.
3 years ago
jeffro
jeffro
Hi Legs!
Currently, it is all sleet/ice with a slight chance of change to snow Monday night for just a short while. IMO.
3 years ago
LoveDelawareSnow
LoveDelawareSnow
I am located in Newark, DE, and a lot of people in the building where I teach are starting to get concerned about Monday. What should we expect? We are just hoping the district administrators are paying attention in case it's really slippery.
3 years ago
Legs
Legs
Thanks Jeffro- nice work! ~ do you see philly N/W Burbs more snow or snow/sleet mix as well....I know it will change 100 more x's...lol
3 years ago
jeffro
jeffro
Looks to be a touch more amped with moisture too.
3 years ago
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