ECMWF (and other models) showing signs of a Decent CAD

[Stormsfury]

event ...

As I expected, the HIGH is MUCH STRONGER (1045 mb) ... that kind of high, the models will completely underestimate the degree of cold air at the surface, especially with the ageostrophic gradient already showing up on tonight's EURO on Day 7 ... furthermore, it looks as if there's some sort of baroclinic zone taking shape off the South Carolina coast on that timeframe ...

EURO Day 6 Mean Sea Level Pressure - Notice the kink in the isobars around SE Missouri as the low moves into a confluent zone ... which by Day 7 should initiate the transfer to a new low along the SC coast in the baroclinic zone ... Surface Low Pressure cannot move through a low level cold dome of air, and hence transfers it's energy in such a matter ... click HERE for an example of a Miller B scenario ... Notice how the SLP's surround the high wedging down the Eastern Side of the Appalachians??

EURO day 7 Mean Sea Level Pressure

EURO Day 6 850mb RH - Overrunning scenario ... look for temperatures to be a bit colder at the surface than the 850mb temperatures themselves ...

IF the EURO's idea verifies, someone could get a little taste of winter ... however, on the other hand ... if the low shears out in the confluent zone, just look for a general raw, cloudy, brisk day (dry CAD wedging).

SF

[Anonymous]

event ...

As I expected, the HIGH is MUCH STRONGER (1045 mb) ... that kind of high, the models will completely underestimate the degree of cold air at the surface, especially with the ageostrophic gradient already showing up on tonight's EURO on Day 7 ... furthermore, it looks as if there's some sort of baroclinic zone taking shape off the South Carolina coast on that timeframe ...

[url=http://vortex.plymouth.edu/cgi-bin/gen_grbcalc.cgi?re=us&mo=ecmwf≤=sfc&va=slp&in=4&pl=cf&ft=6day&cu=latest&overlay=no&mo=≤=&va=&in=&pl=ln&ft=&cu=latest]EURO Day 6 Mean Sea Level Pressure[/url] - Notice the kink in the isobars around SE Missouri as the low moves into a confluent zone ... which by Day 7 should initiate the transfer to a new low along the SC coast in the baroclinic zone ... Surface Low Pressure cannot move through a low level cold dome of air, and hence transfers it's energy in such a matter ... click HERE for an example of a Miller B scenario ... Notice how the SLP's surround the high wedging down the Eastern Side of the Appalachians??

[url=http://vortex.plymouth.edu/cgi-bin/gen_grbcalc.cgi?re=us&mo=ecmwf≤=sfc&va=slp&in=4&pl=cf&ft=7day&cu=latest&overlay=no&mo=≤=&va=&in=&pl=ln&ft=&cu=latest]EURO day 7 Mean Sea Level Pressure[/url]

[url=http://cyclone.plymouth.edu/cgi-bin/gen_grbcalc.cgi?re=us&mo=ecmwf≤=850&va=rhum&in=10&pl=cf&ft=6day&cu=latest&overlay=no&mo=≤=&va=&in=&pl=ln&ft=&cu=latest]EURO Day 6 850mb RH - Overrunning scenario ... look for temperatures to be a bit colder at the surface than the 850mb temperatures themselves ...[/url]

IF the EURO's idea verifies, someone could get a little taste of winter ... however, on the other hand ... if the low shears out in the confluent zone, just look for a general raw, cloudy, brisk day (dry CAD wedging).

SF

So we will have a 1045 mb high wedging down a frigid CAD, with a Low off South Carolina.............Come late next week, we could well be looking at a replay of December 5, 2002, when we got 5 inches of snow here.

If that's the case, maybe I should start wishing for cold weather again! Perhaps a 34/5 T/D spread for a few days..........That would get that ground cold enough for snow accumulation!!

Stay tuned folks..........Same Bat Channel, Same Bat Time.....LOL LOL LOL

[Stormsfury]

So we will have a 1045 mb high wedging down a frigid CAD, with a Low off South Carolina.............Come late next week, we could well be looking at a replay of December 5, 2002, when we got 5 inches of snow here.

If that's the case, maybe I should start wishing for cold weather again! Perhaps a 34/5 T/D spread for a few days..........That would get that ground cold enough for snow accumulation!!

Stay tuned folks..........Same Bat Channel, Same Bat Time.....LOL LOL LOL

Well, right now, the event doesn't look significant, but very noteworthy, as it could indeed mean a taste of winter weather for areas in NC/VA ... but there's been a recent trend for storm systems which don't look like much to trend stronger as we near the short term ... Later runs will be quite interesting.

SF

[RNS]

I completely agree...but the latest EC having that trough off the east coast is a sign that the system should just head out...since the system would be forced to go around the trough. it should be much stronger though...notice the strong cutoff in spain...that says that the system in the east would be more intense as well at the very least...though its probably more likely that it attempts to close off.

the navy NOGAPS off the 12Z run is much more impressive:

12-hr Precip / SLP:

https://www.fnmoc.navy.mil/CGI/PUBLIC/w ... rp&tau=144

Notice low pressure developing in the inverted trough along the east coast...with strong (1040mb) high pres center located further back to the west across Quebec which would supply sufficient LLVL CAD for significant wintry precipitation across the middle atlantic.

500 hPa height and vorticity:

https://www.fnmoc.navy.mil/CGI/PUBLIC/w ... 00&tau=144

we notice tweo pieces of energy...one across the the southeast and a second to the north across new york state. the problem is though that the trough is positively tilted...although it does appear as if the southern end of the trough is attempting to turn meridional (notice there are very slight signs of a baroclinic leaf developing at the base of the trough) as at least partial phasing occurs.

in assessing the potential for wintry precipitation we turn to the H85 feild.

850 hPa heights and temps:

https://www.fnmoc.navy.mil/CGI/PUBLIC/w ... 50&tau=144

the 0C isotherm at 850mb is located near the NC/VA border as the intense high continues to drill in cold air...so it would appear as if thermal profiles would be supportive of snowfall.

SLP and 1000-500 hPa thickness:

https://www.fnmoc.navy.mil/CGI/PUBLIC/w ... hk&tau=144

we also notice the 540 thickness line is realtively close to the 0C isotherm at H85...thus we most likely would be able to use H85 temps to determine the position of the rain/snow line during the event.