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12/3-12/6 MW/GL snow event?

Thundersnow12

By Thundersnow12,
in Central/Western States

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A-L-E-K

A-L-E-K

Posted
Posted

NAM on steroids. Would be pretty cool to see verify though. ;)

I don't see any KLAF Illini posts in the ILL/UNC post game thread over at Loyalty :whistle:

I looked at the NAM before the GFS this morning, chaulked it up to 6z goofiness but then saw the GFS came in wetter as well, if a non crap run comes in the same at 12z, this just might have grass coating potential.

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A-L-E-K

A-L-E-K

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Minor bonus, but with the ground now cold and cold weather expected to hang around until Fri/Sat, we won't be losing too much precious accums to melt on impact. For us lakeside, this is a rarity in December.

EDIT: 12z NAM appears to be picking up where 6z left off.

12z NAM says clipper of the decade?

Ratios might not be total crap.

nam_sl7_072m.gif

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hawkeye_wx

hawkeye_wx

Posted
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Minor bonus, but with the ground now cold and cold weather expected to hang around until Fri/Sat, we won't be losing too much precious accums to melt on impact. For us lakeside, this is a rarity in December.

EDIT: 12z NAM appears to be picking up where 6z left off.

H5 shortwave is even sharper on the 12z. I'm more concerned with the track because I'm still on the sw edge of the better snow. Any slight shift farther south or back north would make a big difference for CR.

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A-L-E-K

A-L-E-K

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H5 shortwave is even a bit sharper on the 12z. I'm more concerned with the track because I'm still on the sw edge of the better snow. Any slight shift farther south or back north would make a big difference for CR.

I won't deny liking where I sit, on northern edge of the good stuff on one model, right in the middle on others, decent ratios and room for shifts either way. Chances of an advisory event have gone way up since yesterday.

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csnavywx

csnavywx

Posted
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H5 shortwave is even a bit sharper on the 12z. I'm more concerned with the track because I'm still on the sw edge of the better snow. Any slight shift farther south or back north would make a big difference for CR.

Don't fret on the placement right now. There's going to be some more jumping before this comes down the pipe. Watch in the next 12-24 hours as this thing comes fully onshore.

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A-L-E-K

A-L-E-K

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What are the chances this thing moves north? If it intensifies and goes negative tilt, it's more likley to go further north correct? I would assume tonights models will have a good handle on the system

I don't think that's happening and corrections north are possible, though probably not huge jumps.

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baroclinic_instability

baroclinic_instability

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What are the chances this thing moves north? If it intensifies and goes negative tilt, it's more likley to go further north correct? I would assume tonights models will have a good handle on the system

I don't think this will be going negative tilt anytime soon. The trend amongst all operational guidance and the last 2-3 SREF mean runs is taking it a tad south as the models are phasing a bit more over the Pacific which seems to be the result of the southward trend.

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Stevo6899

Stevo6899

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I don't think this will be going negative tilt anytime soon. The trend amongst all operational guidance and the last 2-3 SREF mean runs is taking it a tad south as the models are phasing a bit more over the Pacific which seems to be the result of the southward trend.

I always thought in the past that these clippers tend to move south as we get closer to the event. But I also remember last year that a few went way north as time went on. Im assuming teleconnections had something to do with that. In this case the NAO and the colder air is pushing this storm further south. Crazy how this thing dives SE once it gets past the dakotas, like its puposely avoiding Michigan. This storm will be fully sampled by this evening?

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A-L-E-K

A-L-E-K

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I always thought in the past that these clippers tend to move south as we get closer to the event. But I also remember last year that a few went way north as time went on. Im assuming teleconnections had something to do with that. In this case the NAO and the colder air is pushing this storm further south. Crazy how this thing dives SE once it gets past the dakotas, like its puposely avoiding Michigan. This storm will be fully sampled by this evening?

This kind of track (SE then eventually E) is pretty classic for clippers with a decent pac connection, which this one will have.

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Northern_IN_Wx

Northern_IN_Wx

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LOL at the 12z NAM. This clipper does have some pacific moisture to work and could produce a narrow swatch of 3-6" in the southern MN/Northern IA/northern IL/southern WI vicinity. Still would expect some variation in placement through the next several model cycles. I would expect lesser amounts farther southeast given probable shearing of 500mb energy and resultant decreasing isentropic ascent and lift along ascending branch of the developing frontal circulation. The NAM obviously disagrees though. Who knows, this may end up being one of these clippers of roids...

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Northern_IN_Wx

Northern_IN_Wx

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LOL at the 12z NAM. This clipper does have some pacific moisture to work and could produce a narrow swatch of 3-6" in the southern MN/Northern IA/northern IL/southern WI vicinity. Still would expect some variation in placement through the next several model cycles. I would expect lesser amounts farther southeast given probable shearing of 500mb energy and resultant decreasing isentropic ascent and lift along ascending branch of the developing frontal circulation. The NAM obviously disagrees though. Who knows, this may end up being one of these clippers of roids...

I can type? Narrow SWATH :arrowhead:

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Thundersnow12

Thundersnow12

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some of the area AFD's

LOT

FRIDAY NIGHT THROUGH SATURDAY NIGHT...

FOR SEVERAL DAYS NOW OPERATIONAL SOLUTIONS AND ENSEMBLES HAVE

ADVERTISED A SYSTEM PUSHING INTO OUR REGION FRI NGT/SAT. THE PAST

SEVERAL SOLUTIONS HAVE BECOME MORE CONSISTENT IN THE PATH OF THE

850MB LOW...WHICH APPEARS TO SLIDE ACROSS THE CENTRAL/SOUTHERN

SECTIONS OF OUR CWFA FOR THE FIRST HALF OF SAT FROM NW TO SE. THIS

SHUD SETUP A DECENT AREA OF ISENTROPIC LIFT FOR A BULK OF THE AREA

SAT. LATEST ECMWF HAS INCREASED THE MOISTURE DEPTH AND PRECIP

TOTALS...WITH A RANGE BETWEEN 0.2 AND 0.4 INCHES FRI NGT THRU SAT

NGT. SREF PLUMES ARE A BIT MORE AGGRESSIVE WITH PRECIP

TOTALS...HOWEVER THE ENSEMBLE MEAN IS ARND 0.3 INCHES.TEMPS ALOFT

AND AT THE SFC WOULD SUPPORT P-TYPE AS SNOW...SO HAVE CONTINUED THIS

IN THE CURRENT FORECAST. THE ONLY ADJUSTMENT WAS TO INCREASE POPS

SAT TO LIKELY AS CONFIDENCE HAS GROWN. EITHER WAY IT APPEARS LIKELY

THAT ACCUMULATING SNOWFALL WILL OCCUR FOR SAT ACROSS THE

AREA...TAPERING OFF SOMETIME SAT NGT/EARLY SUN.

DVN

FRIDAY NIGHT THROUGH SATURDAY...WILL CONTINUE TO SIDE WITH THE

LATEST ECMWF RUN WHICH OVERALL AS A MODEL HAS BEEN VERY CONSISTENT

IN HANDLING THIS INCOMING SYSTEM OVER THE PAST FEW DAYS. THE EURO

CONTINUES TO DEVELOP THE MAIN SFC WAVE AS IT PROGRESSES FROM THE

CENTRAL PLAINS TO WESTERN KY FRI NIGHT THROUGH MIDDAY SAT. EXTENT

OF FORCING FURTHER TO THE NORTH UNDER LOW TO MID LEVEL WAVE COMBINED

WITH MOISTURE AVAILABILITY SUGGEST BANDED SNOWS ACRS THE NORTHEAST

HALF TO TWO THIRDS OF THE DVN CWA FOR MUCH OF FRI NIGHT INTO SAT. THE

SNOW SHOULD TAPER OFF TO FLURRIES SAT AFTERNOON AND EARLY EVENING...

BUT NOT BEFORE 1-3 INCHES OF ACCUMULATION POSSIBLY OCCURS GENERALLY

ALONG AND NORTH OF I80. A MORE NORTHWEST-TO-SOUTHEAST SLANT TO

FORCING SWATHS MAY BRING A COUPLE INCHES AS FAR SOUTH AS MONMOUTH

IL. IN PRIME DEF ZONE...SOME POTENTIAL OF 4 INCHES FROM MANCHESTER

IA...TO NEAR STERLING AND MT CARROLL IN NORTHWEST IL.OF COURSE

THESE KIND OF DETAILS STILL VERY PRELIMINARY AT THIS POINT...BUT THE

ECMWF HAS SUGGESTED THIS GENERAL SCENARIO FOR THE PAST TWO DAYS. THE

GFS IS COMING AROUND TO THE ECMWF AS WELL FROM RUN-TO-RUN...AND

THINGS ARE POINTING TO A POSSIBLE ADVISORY TYPE EVENT TO START THE

WEEKEND OFF WITH

MKX

FRIDAY NIGHT THROUGH SATURDAY...FORECAST CONFIDENCE...MEDIUM

A POTENT SHORTWAVE WILL RIDE ACROSS A 500MB RIDGE IN THE WESTERN

HALF OF THE CONUS ON FRI...WHILE TROUGHING REMAINS IN THE EAST HALF.

BY 06Z SAT...THE SHORTWAVE SHOULD BE OVER THE DAKOTAS AND MN.

ISENTROPIC LIFT...FRONTOGENETIC FORCING AND STRONG OMEGA JUST AHEAD

OF THE SHORTWAVE...BASICALLY AN INVERTED TROUGH AT THE SFC...WILL

SPREAD SNOW ACROSS MUCH OF THE UPPER MIDWEST FRI NIGHT THROUGH

SATURDAY.

THE LEVEL OF CONFIDENCE IN A SOLID SNOW EVENT FROM FRI NIGHT THROUGH

SAT AFTERNOON/EVENING IS RISING. THE LATEST MODEL RUN...00Z

ECMWF...00Z GFS...06Z NAM QPF FIELDS CAME INTO REMARKABLE AGREEMENT

SPATIALLY. HOWEVER...QPF AMOUNTS STILL DIFFER QUITE A BIT.

THE 00Z ECMWF SPED UP JUST A BIT TO BETTER AGREE WITH PRECIP TIMING

ACROSS SOUTHERN WI IN THE 00Z GFS. BUMPED UP POPS TO LIKELY IN SW

CWA AFTER 06Z SAT...AND THEN CONTINUED LIKELY POPS FOR MOST OF

SOUTHERN CWA THROUGH 00Z SUN.

QPF IS THE TRICKIER FIELD TO COME TO A CONSENSUS. THE GFS QUICKLY

MOVES THE SYSTEM SOUTHEAST WHILE THE ECMWF SHOWS A SECONDARY

ENHANCEMENT IN QPF AS THE SHORTWAVE DIGS A LITTLE NEAR THE OH RIVER

VALLEY. WENT WITH A BLEND OF GFS AND ECMWF WITH A LITTLE MORE WEIGHT

ON THE ECMWF DUE TO ITS CONSISTENCY. USED SNOW RATIOS AROUND 14 IN

THE SOUTHEAST AND 17 UP NORTH...A BLEND OF THE NAM AND GFS SNOW

RATIOS. SNOW AMT FROM QPF STORM TOTAL FROM FRI EVE THROUGH SAT

AFTERNOON WITH A FAIRLY CONSERVATIVE BIAS SHOWS 5 TO ALMOST 6 INCHES

IN SOUTHWEST CWA STORM TOTAL...4 TO 5 INCHES IN CENTRAL CWA...AROUND

3 INCHES NEAR MKE...AND ALMOST 2 INCHES NEAR SHEBOYGAN STORM TOTAL.

THIS SPELLS ADVISORY AMOUNTS FOR PORTIONS OF SOUTH CENTRAL WI. WILL

NOT ISSUE ADVY AT THIS TIME...BUT IF MODELS REMAIN

CONSISTENT...WOULD NOT HESITATE TO ISSUE AT A LATER TIME PERIOD.

ARX

FRIDAY EVENING AND OVERNIGHT...NAM12 SHOWING STRONG 850-700MB

FRONTOGENESIS MOVING INTO SOUTHWEST PORTION OF THE FORECAST AREA

WITH ALMOST VERTICAL AGEOSTROPHIC CIRCULATIONS DUE TO COUPLED JET

STRUCTURE ACROSS THE REGION. THIS HAS THE POTENTIAL TO SET UP NW-SE

BANDED SNOW STRUCTURE ACROSS SOUTHWEST PORTIONS OF THE FORECAST AREA

FOR ENHANCED SNOWFALL. IN FACT...NAM COBB OUTPUT IN GFE YIELDING A

BAND OF 6-10 INCHES OF SNOWFALL FROM DODGE CENTER MN THROUGH DUBUQUE

IA. THE GFS IS A BIT MORE BROAD-BRUSHED WITH 3-5 INCHES CENTERED

ALONG THE MISSISSIPPI RIVER. LINGERING DEFORMATION SNOW ON SATURDAY

AS THE WAVE DIVES SOUTHEAST TOWARD THE OHIO RIVER VALLEY MAY PRODUCE

ANOTHER COUPLE OF INCHES. WITH SUPPORT FROM THE 01.00Z ECMWF/GEM AS

WELL...HAVE PUSHED POPS ACROSS SOUTHWEST PORTIONS OF THE AREA INTO

THE LIKELY CATEGORY. IF CURRENT TRENDS CONTINUE WILL LIKELY NEED AN

ADVISORY FOR FRIDAY NIGHT INTO SATURDAY...POSSIBLY WARNING

HEADLINES. WILL HAVE TO KEEP A CLOSE EYE ON THIS SITUATION AND WILL

PASS CONCERN ONTO THE DAY SHIFT FOR FURTHER ASSESSMENT.

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