The "New" Milli Bar

philnyc · sfc 2009-03-01 18Z

Oh, boy! Look at this classic setup. Cyclogenesis over the Carolinas with almost perfect 500mb positioning and a left exit of jet streak right over it as it moves along the Delmarva. NYC NWS has 10-14 inches and I have to concur right now. This setup could even produce some thundersnow.

The only possible forecast busters? What's missing here from the classic setup is the cold air damming over New England southward along the Appalachians (see current surface chart). So if the 850mb zero C line moves further westward we get rain/sleet mixed in at the coast. Or if the low center itself moves closer to the coast we'll get the same result. But I wouldn't count on it this time.

Weatherfox · Posted: Sun Mar 01, 2009 22:15 pm Post subject:

Good luck Phil. I'm a little jealous because Pittsburgh, PA is overdue its foot plus snowstorm. I was back home in February 2006 when NYC set its record snowfall of 26.9" in Central Park and as a SKYWARN spotter reported 19.9" in Flushing NY. The 12 and 24 hour NGM/GFS soundings for KLGA shows an all snow profile which makes sense with the forecasted off shore track of the coastal storm. Also, with the NE winds at 20 knots you should have considerable drifting of the snowfall.

philnyc · 500mb ruc 2009-03-02 00Z

Thanks for that, Glenn. However, it's beginning to look like another forecast bust for this one. There seems to be considerable dry air now moving in from the west, and I also see the low center forming a little further SE of Hatteras than forecast. And the 500mb low seems to be getting decoupled from the forming surface low center. In addition the very high 300mb flow along the east coast is going to scoot this northeastward very quickly. Net result? a lot less than they're forecasting. I'm going with 6-8 now.

philnyc · Posted: Mon Mar 02, 2009 14:02 pm Post subject:

We have 5.9 at LaGuardia and 5.0 at Kennedy as of 9AM with 1-2 more inches coming. So I'm happy with my forecast.

MAThornton · Joined: 20 Sep 2007 Posts: 833 Location: Cleveland, Ohio

Phil,

Yes, your forecast is looking pretty good. The meteograms for JFK and Islip show a fairly steep snow gradient across Long Island. How far do you live from JFK?

The dry conveyor belt shows up very nicely on the water vapor imagery.

I also cut the following comments from the AFD issued at 7:30 am this morning. I don't have time at the moment to look into this, but it sounds quite interesting.

STRONG INERTIAL GRAVITY
WAVE APPROACHING SOUTH COAST OF LI. 5-9MB PRESSURE PERTURBATION
AND WIND GUSTS TO 60KTS NOTED...

SNOWFALL SHUTS OFF ABRUPTLY BEHIND THE GRAVITY WAVE...AND THERE
MAY BE A 2-3 HOUR LULL ACROSS MUCH OF THE AREA.

Mark

philnyc · Posted: Mon Mar 02, 2009 16:54 pm Post subject:

Thanks for that additional analysis. I live only about 6 miles NW of JFK. I would estimate that we got about 7 inches by us before I left for work at 7AM. I was asleep during the best parts and then when I got up that big lull with the dry slot came in.

I had no idea about the "gravity wave" - I'll have to look at the radars later at home to see what the flock they were talking about.

Finally, the count is 7 inches at Central Park and it's pretty much over. The NWS forecast was 10-14 inches. Their AFDs all day yesterday kept talking about deformation zones and dendritic growth areas. While this is a lot of fun and I love it, I think it's crazy to try and incorporate def zones into a forecast like this. The following attached radar from a little while ago shows my point. KNYC Central Park and all of NYC for that matter, are sitting in between the 2 deformation zones which are drifting slowly north-northeast. There is no technology yet available to forecast a mesoscale event like this.

TheGrenc · Joined: 24 Sep 2007 Posts: 1105

Sorry I haven't said much. I've been in seclusion. Smile

MAThornton · Joined: 20 Sep 2007 Posts: 833 Location: Cleveland, Ohio

The Grenc strikes!

Looks like a day for cloud streets in the GOM.

philnyc · Posted: Mon Mar 02, 2009 19:40 pm Post subject:

Excellent, Lee. I noticed it a little earlier today but you beat me to it. Those images are very impressive. Thanks for posting.

TheGrenc · Joined: 24 Sep 2007 Posts: 1105

I looked at Buoy 41001 (south of the seclusion) ... it has a screamin' easterly wind ... see attached.

That's really odd ... I think it may be because the buoy went adrift:

http://www.ndbc.noaa.gov/station_page.php?station=41001

Loved the link to the right whales. Cheers.

MAThornton · Joined: 20 Sep 2007 Posts: 833 Location: Cleveland, Ohio

Lee,

Based upon the lat and long, the buoy is northeast of Bermuda and well on its way to Europe.

Mark

TheGrenc · Joined: 24 Sep 2007 Posts: 1105

Thanks Mark.

I'd like to be on my way to Europe.

philnyc · Posted: Mon Mar 02, 2009 23:54 pm Post subject:

Ha ha to both of you. Meanwhile, did anyone notice the reading just SE of the eastern end of Long Island? Thundersnow! I got it right. I was looking for reports of thunder and lightning and hadn't found any. I have been dying to do a report on severe nor'easters with seclusion plus thundersnow, so this one can now go into my study. I'm so glad you posted that Lee. Thanks.

MAThornton · Joined: 20 Sep 2007 Posts: 833 Location: Cleveland, Ohio

Phil,

Don't forget about the "bonus" gravity wave.

Mark

TheGrenc · Joined: 24 Sep 2007 Posts: 1105

Folks,

I no longer believe that the "donut" I noticed on satellite imagery is a warm seclusion.

The westerly flow to the south of the storm is just not strong enough to trap/seclude warmer air near the center by differential horizontal advection.

Sorry for not looking at this more closely. I noticed it and reacted. I should have checked more thoroughly. I apologize. Lee