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January 19-21 MW/GL/OV Storm part 2


Hoosier

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True, true. It's really the NAM against the world, and the 18z Run took a good step towards the others I think.

Still, a really good hit for KC to STL on east through CVG.

Does anyone know yet whether or not the system is onshore and or if it got into modeling?

For those up this way wondering..

nam_500_030s.gif

That stuff crossing the lakes is what basically screws us from the system coming north.

This closer in does not help either. See the SE coast.

nam_500_018s.gif

What they both do is keep ridging ahead of the system in check which keeps the system further south as it passes us by to the south and east. Thus lose that crap and we have ourselves a better chance of a snowstorm up this way. Unless the storm can find a way to phase alot quicker. Chances of either happening i think are slim at best. Yeah models can be off a bit but i don't see them being that far off. JMHO

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Also goes to show how tiny changes in the height field can equate to massive eventual differences when positive feedback is in effect. A slightly weaker phase results in large differences in the end. Expect an even weaker phase on the NAM for 0Z--don't attack me here--but I wouldn't expect the 0Z NAM to bring any miracles.

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Color me surprised by this out of IND..

URGENT - WINTER WEATHER MESSAGE

NATIONAL WEATHER SERVICE INDIANAPOLIS IN

350 PM EST TUE JAN 18 2011

...WINTER STORM WATCH IN EFFECT FROM LATE WEDNESDAY NIGHT THROUGH

LATE THURSDAY NIGHT...

.AN UPPER LEVEL DISTURBANCE WILL MOVE INTO CENTRAL INDIANA LATE

WEDNESDAY NIGHT BRINGING ACCUMULATING SNOWFALL.

* MAIN IMPACT: ROADS WILL BECOME VERY SLIPPERY DUE TO HEAVY SNOW

AND DRIFTS...REDUCED VISIBILITIES...TRAVEL MAY BECOME VERY

HAZARDOUS. RUSH HOURS WILL BE AFFECTED.

* ACCUMULATIONS: 4 TO 6 INCHES

* TIMING: HEAVIEST SNOWFALL EXPECTED DURING THE THURSDAY 7 AM TO

7PM TIME FRAME.

* OTHER IMPACTS: WINDS WILL INCREASE ON THE BACK SIDE OF THE STORM

CAUSING BLOWING AND DRIFTING SNOW.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR SIGNIFICANT

SNOW...SLEET...OR ICE ACCUMULATIONS THAT MAY IMPACT TRAVEL.

CONTINUE TO MONITOR THE LATEST FORECASTS.

:yikes:

I probably would have left out everyone north of IND, but I'm not one to criticize their expertise. :) Maybe the blowing/drifting potential is part of the WSW thought, despite lower amounts up here. I haven't seen their AFD yet, so we'll see.

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Also goes to show how tiny changes in the height field can equate to massive eventual differences when positive feedback is in effect. A slightly weaker phase results in large differences in the end. Expect an even weaker phase on the NAM for 0Z--don't attack me here--but I wouldn't expect the 0Z NAM to bring any miracles.

Fine by me, then the northern vort will be progged to ride straight threw here.

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Also goes to show how tiny changes in the height field can equate to massive eventual differences when positive feedback is in effect. A slightly weaker phase results in large differences in the end. Expect an even weaker phase on the NAM for 0Z--don't attack me here--but I wouldn't expect the 0Z NAM to bring any miracles.

And last night you were talking apocolypse. I see it this way. Models trended away last night, whos to say they dont trend back. It's slim, but could happen.

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And last night you were talking apocolypse. I see it this way. Models trended away last night, whos to say they dont trend back. It's slim, but could happen.

No they likely won't Dilly. I am just saying there are things one can track and there are reasons why all this happens--and those reasons are quite clear that this won't be as good as it could have been--but it will still be a moderate event.

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And last night you were talking apocolypse. I see it this way. Models trended away last night, whos to say they dont trend back. It's slim, but could happen.

No I said the NAM was apocalyptic in its depction of events, but also said there is a fair probability that won't happen. Meteorology/forecasting is a game of probabilities and threats.

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Does anyone know yet whether or not the system is onshore and or if it got into modeling?

For those up this way wondering..

That stuff crossing the lakes is what basically screws us from the system coming north.

This closer in does not help either. See the SE coast.

What they both do is keep ridging ahead of the system in check which keeps the system further south as it passes us by to the south and east. Thus lose that crap and we have ourselves a better chance of a snowstorm up this way. Unless the storm can find a way to phase alot quicker. Chances of either happening i think are slim at best. Yeah models can be off a bit but i don't see them being that far off. JMHO

spot on Harry....there's always something f*cking with our ridging in front this season. I believe the last storm had some damn rogue piece traveling along the gulf coast states as well.

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spot on Harry....there's always something f*cking with our ridging in front this season. I believe the last storm had some damn rogue piece traveling along the gulf coast states as well.

Yep good call by Harry. And yeah the last storm had the deep South snowstorm frontrunner.

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iln pulls the trigger for sw counties.. not for you though buckeye

INCLUDING THE CITIES OF...BROOKSVILLE...MOUNT OLIVET...

MAYSVILLE...VANCEBURG...WASHINGTON COURT HOUSE...CIRCLEVILLE...

LANCASTER...CHILLICOTHE...LOGAN...GEORGETOWN...HILLSBORO...

WEST UNION...PIKETON...PORTSMOUTH

357 PM EST TUE JAN 18 2011

...WINTER STORM WATCH IN EFFECT FROM THURSDAY MORNING THROUGH

FRIDAY MORNING...

THE NATIONAL WEATHER SERVICE IN WILMINGTON HAS ISSUED A WINTER

STORM WATCH...WHICH IS IN EFFECT FROM THURSDAY MORNING THROUGH

FRIDAY MORNING.

LOW PRESSURE WILL DEVELOP OVER THE SOUTHERN PLAINS ON WEDNESDAY.

THE LOW IS FORECAST TO MOVE THROUGH TENNESSEE ON THURSDAY...THEN

TO THE ATLANTIC COAST ON FRIDAY. A BAND OF MODERATE TO HEAVY SNOW

ASSOCIATED WITH THE LOW IS EXPECTED TO DEPOSIT SIGNIFICANT SNOW

ACCUMULATIONS OVER SOUTHERN OHIO AND NORTHEAST KENTUCKY. THE

LATEST COMPUTER MODEL PROJECTIONS INDICATE THAT 3 TO 5 INCHES OF

SNOW MAY FALL ACROSS THE WATCH AREA. GUSTY WINDS AND COLDER

TEMPERATURES FOLLOWING THE LOW WILL BRING DRIFTING SNOW AND COLD

WIND CHILLS TO THE REGION BY FRIDAY MORNING.

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WWA up already for central IL, basically along and south of a line from Havana to Danville. Seems a bit early for an advisory issuance, alas they must be confident. :)

Relevant portion of their AFD BTW

OUR PRIMARY AREA OF CONCERN IS WITH THE SNOW POTENTIAL FOR

WEDNESDAY NIGHT AND THURSDAY. THE MODELS HAVE SUPPORTED

ACCUMULATING SNOW DURING THIS PERIOD FOR SOME TIME NOW...AND THE

TIME HAS COME TO TRY AND NAIL DOWN MORE SPECIFICITY IN THE

FORECAST. A WAVE IN THE NORTHERN AND SOUTHERN STREAMS OF THE

WESTERLIES WILL BE IN THE PROCESS OF PHASING AS THEY MOVE ACROSS

THE FORECAST AREA. THE MODELS SUGGEST A PROLONGED PERIOD OF

RELATIVELY WEAK ISENTROPIC ASCENT...WITH MIXING RATIOS ON THE

ORDER OF 2-3 G/KG DURING THE PERIOD OF LIFT. HOWEVER...THE DYNAMIC

FORCING IS MORE IMPRESSIVE...WITH MUCH OF THE FORECAST AREA UNDER

THE RRQ OF THE LEAD JET STREAK IN ADVANCE OF THE WAVE WEDNESDAY

NIGHT...WITH SOME JET COUPLING NOTED AS THE WAVE COMES OVERHEAD ON

THURSDAY. MOST MODELS ALSO SUGGEST FAIRLY STRONG LOW/MID LEVEL

FRONTOGENESIS DURING MUCH OF THE PERIOD...THOUGH IT IS FAIRLY

BROAD AND THIS MAKES IT TOUGH TO PINPOINT A FAVORED AREA FOR A

HEAVY SNOW BAND. IN ADDITION...DURING THE EXPECTED PERIOD OF

HEAVIER SNOWFALL...MUCH OF THE FORECAST AREA WILL HAVE A FAIRLY

DEEP...SATURATED...ISOTHERMAL LAYER AROUND -10C. WHILE THIS IS NOT

THE IDEAL TEMPERATURE FOR MAXIMUM DENDRITIC SNOW FLAKE GROWTH...IT

IS STILL FAIRLY FAVORABLE. SO...WITH ALL THIS BEING SAID...IT

APPEARS LIKELY THAT 3-5 INCHES OF SNOW WILL BE COMMON ACROSS THE

FORECAST AREA...HEAVIEST IN THE SOUTH/LIGHTEST IN THE NORTH...BY

THE TIME THE SNOW TAPERS OFF THURSDAY AFTERNOON/EVENING. LOCALLY

HIGHER TOTALS ARE CERTAINLY POSSIBLE ACROSS THE SOUTHERN HALF OF

THE FORECAST AREA.

WILL ISSUE A WINTER WEATHER ADVISORY FOR SNOW FOR COUNTIES

ALONG/SOUTH OF A SCHUYLER/VERMILION COUNTY LINE...STARTING AS

EARLY AS 00Z THURSDAY AND ENDING AT 00Z FRIDAY. CAN NOT RULE OUT

THE ADVISORY NEEDING TO BE EXPANDED FURTHER NORTH AND/OR UPGRADED

TO A WARNING ACROSS A FEW COUNTIES IN THE SOUTH...BUT THIS

ADVISORY APPEARS TO BE A GOOD FIRST STEP.

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WWA up already for central IL, basically along and south of a line from Havana to Danville. Seems a bit early for an advisory issuance, alas they must be confident. :)

Headline wise, this is a high confidence event in some regards. The main uncertainty has lied in the amount of phasing.

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IND AFD. Not a bad read...a little short, but to the point.

.SHORT TERM /TOMORROW THROUGH FRIDAY/...

THE MAIN FOCUS IS THE UPCOMING WINTER STORM. ISSUED A WINTER STORM

WATCH IN EFFECT FROM THU 06Z - FRI 06Z.

DYNAMICS HAVE BECOME MORE IMPRESSIVE WITH LATEST RUNS. UPPER LEVEL

TROUGH IS PROGGED TO MOVE INTO CENTRAL INDIANA ON WEDNESDAY NIGHT.

GENERALLY WENT WITH A BLEND OF GFS/NAM/EURO. ISENTROPIC LIFT WILL

START OVER THE WESTERN PORTIONS OF THE AREA AROUND THU 00Z...AND

WILL REALLY GET GOING OVER THE ENTIRE FORECAST AREA AROUND THU

06Z. CURRENT THINKING IS THAT THE HEAVIEST SNOW WILL FALL IN THE

THUR 12-00Z TIME FRAME.

IMPRESSIVE FRONTOGENETIC BANDING IN THE MID LEVELS MATCHES UP

NICELY WITH THE BEST ISENTROPIC LIFT AND 100+ KT UPPER LEVEL JET.

ANTICIPATE ISOLATED AREAS OF OVER 6 INCHES WHERE THE BEST BANDING

SETS UP.

ISENTROPIC LIFT WILL CUT OFF ABRUPTLY AROUND FRI 03Z. THE UPPER

LEVEL TROUGH WILL MOVE THROUGH AROUND FRI 06Z ADDING ADDITIONAL

LIFT...BUT MOISTURE WILL ALREADY BE OUT OF THE AREA. SO...DO NOT

EXPECT MUCH IN THE WAY OF ADDITIONAL ACCUMULATION.

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Baro, do you have any thoughts on the potential for banded precip?

For LAF and that region probably nothing special. Of course short-lived mesoscale bands can be expected with any rapidly developing system, but it does seem the best persistent mesoscale banding threat will be farther S and E after the phase. From an IPV standpoint, what the NAM and all models are doing is triggering the development of the upper level cold front down towards the surface after the phase. You can see that in the 500 hpoa vorticity fields from around 51-66 hours as the height fields rapidly respond (increased shear vorticity as wind fields rapidly strengthen) to an increasing thermal gradient as the tropopause lowers. In short--the best banding will be along the developing low level cold front as frontogenesis develops. Most of that activity will probably be in KY and just S of you--aka southern IN

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Merzlock (LOT) throwing in some :weenie: jabs. :guitar:

THE 18Z NAM IS IN AND TAKES THIS ENERGY EVEN FURTHER SOUTH.

WELL...AS TIBERIUS WOULD SAY...EX NIHILO NIHIL FIT. JUST PAR FOR

THE COURSE IN A WINTER OF MISSED OPPORTUNITIES AS FAR AS SNOW IS

CONCERNED.

Yikes--that was a discussion?

If so that is surprising they would say that publicly.

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Yikes--that was a discussion?

If so that is surprising they would say that publicly.

It was a snippet of the entire relative portion of the AFD below. I thought it was a little funny, considering again, Chicagoland (especially the western and south/southwestern suburbs) is above normal to date with snowfall. But that's a dead horse topic I wish not to relive. ;)

MORE ENERGETIC SYSTEM NOW MAKING LANDFALL ACROSS THE PAC NW WILL BE

EMERGING FROM THE CENTRAL ROCKIES BY WEDNESDAY EVENING. THIS SYSTEM

WILL BE PASSING WELL TO S OF AREA WED NIGHT-THURSDAY. WITH TROUGH

BECOMING POSITIVELY SHEARED WITH TIME...AS NRN BRANCH SHORT WAVE

AMPLIFIES FROM SRN CANADA...SEWD ACROSS THE WRN GREAT LAKES...THIS

FEATURE IS EXPECTED TO EJECT EWD ACROSS THE TN VALLEY THURSDAY. IN

ADDITION...INITIALLY DECENT LOW LEVEL FORCING ACROSS CENTRAL PLAINS

WILL LIKELY PRODUCE SOME SIGNIFICANT SNOWFALL ACROSS CENTRAL

PLAINS...THROUGH THE KC AREA...BUT SHOULD FIZZLE AS IT APPROACHES

THE MS RVR WED NIGHT AS LOW LEVEL FLOW IS FORCED TO LAY OVER TO A

WSW-ENE ORIENTATION WITH ANY NOTABLE ISENTROPIC LIFT LAYING OUT

ACROSS THE LOWER OH VALLEY. THUS AM HARD PRESSED TO EVEN KEEP A

SLIGHT CHC POP IN ACROSS PORTIONS OF FA ALONG/N OF I-80. FURTHER

SOUTH AND EAST...INTO EAST CENTRAL IL/W CENTRAL IN PORTIONS OF

FA...WILL GO WITH LIKELY POPS WED NIGHT-THUR MORNING PERIOD...WITH

FCST QPF/SNOW AMOUNTS...PERHAPS...SUPPORTING AS MUCH AS 1-3 INCHES.

MOST OF FORECAST AREA SHOULD SEE ONLY A MID/HIGH LEVEL OVC WITH

THIS. THE 18Z NAM IS IN AND TAKES THIS ENERGY EVEN FURTHER SOUTH.

WELL...AS TIBERIUS WOULD SAY...EX NIHILO NIHIL FIT. JUST PAR FOR

THE COURSE IN A WINTER OF MISSED OPPORTUNITIES AS FAR AS SNOW IS

CONCERNED

.
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