Dec 5-6 Round Two? NAM brings "sling-shot" Upper Low into SW and the fun has just begun!

[kab2791]

Yep, GFS still has a progressive look, but an improvement at least.

There's still quite a difference between how the NAM and GFS handle things.

[cyclone77]

Latest SREF mean shows best axis from Joplin through St. Louis/Springfield Illinois, up through LAF to Detroit.

[wxhstn74]

Blog Update

http://weatherhistorian.blogspot.com/2011/12/potential-new-snow-system-to-affect.html

[SpartyOn]

Blog Update

http://weatherhistor...-to-affect.html

These situations are the best for insane snows around the area if Im not wrong. It snows heavy for long periods and with the front just at the back door it creates a heavy wet snow.

[Hoosier]

lol...NAM is dangerously close to missing LAF to the north.

[kab2791]

MODEL DIAGNOSTIC DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

1145 PM EST FRI DEC 02 2011

VALID DEC 03/0000 UTC THRU DEC 06/1200 UTC

...SEE NOUS42 KWNO ADMNFD FOR THE STATUS OF THE UPPER AIR

INGEST...

00Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES

MODEL INITIALIZATION ERRORS DO NOT APPEAR TO HAVE A SIGNIFICANT

IMPACT ON THE FORECAST.

...ENERGY REACHING THE SOUTHWEST BY MON...

...TROF REMAINING OVER THE PLAINS/NRN TIER MON ONWARD...

PREFERENCE: NAM/12Z ECMWF COMPROMISE

THE GFS SHOWS A FARTHER EWD TRACK OF THE WRN CONUS ENERGY VERSUS

THE NAM FROM SUN ONWARD. BY F84 EARLY TUE THE GFS TRENDS TOWARD A

LESS POSITIVELY TILTED PLAINS/NRN TIER TROF THAN THE NAM... AND

DISPLAYS MUCH GREATER PHASING BETWEEN NRN TIER AND SWRN ENERGY IN

CONTRAST TO THE NAM THAT MAINTAINS A CLOSED MID LVL CENTER OVER

THE AZ/NM BORDER. OTHER MODEL/ENSEMBLE GUIDANCE DEVELOPS AT LEAST

A MEDIUM AMOUNT OF SPREAD BY LATE IN THE PERIOD. THE MOST COMMON

THEME IS TOWARD SLOWER PROGRESSION OF THE WRN CONUS ENERGY THAN

THE GFS... AND GREATER POSITIVE TILT OF PLAINS/NRN TIER ENERGY

THAN THE GFS. THE 21Z SREF MEAN BECOMES THE WWD/SLOW EXTREME WITH

THE SWRN CONUS ENERGY WHILE THE 18Z GEFS MEAN IS ALSO RELATIVELY

SLOW BUT NOT AS DEEP/WWD AS THE SREF MEAN. RECENT HISTORY OF

GUIDANCE IN THIS MEAN PATTERN HAS NOT FAVORED ERN SOLNS EITHER...

AND THE GFS FLATTENS THE UPSTREAM RIDGE MORE THAN CONSENSUS BY

MON... SO WILL CONSIDER THE GFS AS THE LEAST LIKELY SCENARIO.

HOWEVER WITH THE ECMWF HAVING BEEN ONE OF THE MORE STABLE/RELIABLE

PIECES OF GUIDANCE IN THIS PATTERN... AND OFFERING A SOLN THAT

ACTUALLY TRENDS A LITTLE FASTER THAN THE NAM... WOULD NOT WANT TO

GO ANY FARTHER WWD THAN A NAM/12Z ECMWF COMPROMISE AT THIS TIME.

MEANWHILE BY F84 EARLY TUE THE NAM TRENDS A BIT TOWARD THE DEEP

SIDE OF THE NON-GFS SPREAD WITH THE PLAINS/NRN TIER TROF. THESE

CONSIDERATIONS FAVOR A NAM/12Z ECMWF COMPROMISE AS THE BEST

STARTING POINT FOR THE FCST AT THIS TIME. CONFIDENCE IS SLIGHTLY

BELOW AVERAGE.

[cyclone77]

lol...NAM is dangerously close to missing LAF to the north.

It's definitely an outlier at this point. Although as others have mentioned the general trend is in the NAM's direction. The NAM didn't do all that great with a few of the last systems, so take that for what it's worth lol.

[Thunder Road]

GFS gives VPZ 0.33", all as SN, although with some possible non-sticking issues and very drawn out over 30 hours.

NAM gives me 0.92" all theoretically all SN.

I'd really like to see the non-US models get on board now.

[Stebo]

This event has me very interested, as these waves that ride up tight baroclinic zones normally yield very nicely. Also with the gulf being open for business with the return flow around the high along the East Coast, you know this is going to be a moisture ladened system. I wouldn't be at all surprised to see QPF amounts go up as we move forward toward this event. Also as someone noted earlier in the thread that high moving Southeast from Canada will allow for a nice gradient between the system and the high pressure allowing for some wind to be thrown into the mix.

[snowlord81]

A bit off topic but the new GFS drops the cold hammer on us next weekend after a minor (but probably high ratio snow) It shows -20c at 850 next Saturday.

[cyclone77]

New GEM buries the energy in the SW. Hopefully the Euro makes another step towards the NAM. If it looks like the GEM my skepticism will begin to climb a little more.

[toronto blizzard]

It looks as if the 00z GEM keeps alot of energy closed off in the SW but still carries out the frontal boundary. Eventually all that SW energy gets ejected and forms another pretty nice storm that would give us some nice snows

[Hoosier]

00z UKMET upper air look is almost a carbon copy of the NAM at 72 hours.  Maybe even a tad northwest if anything.  Sometimes it is a hint at which way the Euro will go.

[BeastFromTheEast]

Gotta love that epic OK to MO band lol

Quite a screw zone there in between the bands lol..

[Chicago Storm]

00z UKMET upper air look is almost a carbon copy of the NAM at 72 hours. Maybe even a tad northwest if anything. Sometimes it is a hint at which way the Euro will go.

[cyclone77]

Is it just me, or do those thicknesses seem way too warm?

[SpartyOn]

A 0z NAM panel of interest for the semi crew.

[Hoosier]

Is it just me, or do those thicknesses seem way too warm?

Careful, those are heights.

[Stebo]

Is it just me, or do those thicknesses seem way too warm?

Height lines are on that map, though I do agree the 500mb heights are a bit high. The other concern is the Western high is lagging behind way too much.

[Hoosier]

I'd love to see what the UKMET does between 96 and 120. If you look at the 96 hour map you'd never guess that there'd be a 1000 mb low in Kentucky at 120 hours.

[cyclone77]

Careful, those are heights.

Ahh, I see. Apparently I'm blind as I don't see thicknesses plotted on that map even though the legend has it in there.

[SpartyOn]

OT.

Waiting up late at night for a model is like meeting an old friend at the bar.

[Chicago Storm]

0z ECMWF is coming north...

[cyclone77]

0z ECMWF is coming north...

:popcorn:

[Hoosier]

Euro definitely north at 72 hours...more prominent inverted trough and precip shield farther north.  0C 850 mb almost right over LAF.

[Hoosier]

Although north it looks like the Euro won't be as juiced as the NAM.Edit:  well close maybe

[Chicago Storm]

I'd love to see what the UKMET does between 96 and 120. If you look at the 96 hour map you'd never guess that there'd be a 1000 mb low in Kentucky at 120 hours.

Check out the 0z GGEM...It appears the UKMET is a farther NW version.

[kab2791]

Nice hit for BTL/LAN/FNT

A couple inches from ORD to MOP

[Thundersnow12]

Euro definitely north at 72 hours...more prominent inverted trough and precip shield farther north. 0C 850 mb almost right over LAF.

Oh yes..1012mb sfc low in western KY southeast of Evansville.

Then moves into western OH at 78hr.

[Chicago Storm]

Can we get the topic title changed to reflect the time period in question?

kthx