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Possible Snow Threats and Upcoming Cold Spell


Snow_Miser

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Ratios NW of I-80/I-287 are 14:1 or better. A lot of precip also falls during the coldest part of the day (early morning hours). It's a first guess, still time for the models to swing one way or another.

 

I wouldn't expect those kind of ratios with this sort of a sounding...

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The NAM's crazy depiction of the event at Day 3-4 shows why this model should just not even be run past 60 hours, its just a waste of NCEP's money if you ask me.

It treneded much strong with the northern stream shortwave phasing in over Oklahoma. The end result is a stronger storm that takes longer to shear out. Probably wouldn't make much difference for us anyway.

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Don't use surface temperatures or 850s for ratios. Use the temperatures of the snow growth region, and look at how saturated the snow growth region itself is. Ideally, you want your snow growth region to have temperatures between -12 and -18 C for best dendrite growth. This is when the difference between the saturation vapor pressure with respect to ice and the saturation vapor pressure with respect to water is the greatest, which allows for the most efficient snow growth. 

 

Also, you want good omega/lift in the snow growth region, as well. 

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You'll have to excuse me. My level of amateur weather nerd hasn't quite progressed to the point where I can properly understand those soundings without help.

 

 

You'll have to excuse me. My level of amateur weather nerd hasn't quite progressed to the point where I can properly understand those soundings without help.

in short ... You are goin to be 10 -1 .

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It's rain for everyone in the metro area aside from perhaps a brief period of snow/sleet in the Far N and W suburbs.

 

Very warm run.

 

Very large thermal differences between models right now.

That's not the storm I was referring too. I was talking about the storm over the central and southern US. It looked for a little while like the PV might be displaced enough to allow heights to build over the ocean. That's not the case. The pig PV comes down in the end and squashes everything.

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That's not the storm I was referring too. I was talking about the storm over the central and southern US. It looked for a little while like the PV might be displaced enough to allow heights to build over the ocean. That's not the case. The pig PV comes down in the end and squashes everything.

 

I think it's nearly a lock that the friday storm should pass to the south of us because of all of the confluence to the north and the PV suppressing any coastal system trying to form and move up along the coast.

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HPC Outlook - losing confidence in the extent of the arctic air

 

EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
1020 AM EST MON JAN 14 2013

VALID 12Z THU JAN 17 2013 - 12Z MON JAN 21 2013


USED THE 00Z/14 ECMWF FOR THE FRONTS AND PRESSURES FOR DAYS 3
THROUGH 5, THEN SWITCHED TO THE 00Z/14 ECENS MEAN DAYS 6 AND 7 TO
MITIGATE THE SYNOPTIC DETAIL UNCERTAINTY INHERENT TO THAT TIME
RANGE. THE 00Z/14 GFS--UPON WHICH THE LATEST MOS IS BASED--WAS A
DEVELOPED OUTLIER WITH THE WAVE CROSSING THE GREAT LAKES DURING
THE PERIOD. THE GEM GLOBAL AND UKMET HAVE HAD A STRING OF VOLATILE
SOLUTIONS. THE DETERMINISTIC ECMWF, WHILE NOT STABLE EITHER, HAS
BEEN USABLE WHEN IT HAS JIBED WITH ITS ATTENDANT MEAN--AS IS THE
CURRENT CASE. THE PATTERN IS A DRY ONE AS A WHOLE FOR THE NATION,
WITH A RIDGE OVER THE WEST AND CONTINENTAL POLAR AND ARCTIC AIR
POURING INTO THE CENTRAL AND EAST. WHILE THE SOUTHEAST RIDGE IS
STILL IN PLACE, A COUPLE MORE WAVES MAY BE FORCED FAR ENOUGH
NORTHWARD TO PRODUCED STRIPES OF LIGHT PRECIPITATION FROM THE
TENNESSEE VALLEY EASTWARD TO THE MID ATLANTIC AND CAROLINA COASTS.

IN TERMS OF THE ARCTIC AIR, THE MODELS HAVE BEEN ADVERTISING AN
EVENTUAL TRANSPORT OF THE SUPERFRIGID AIR OVER CANADA IN THE
NORTHERN TIER OF STATES FOR SOME TIME NOW--USUALLY AT THE END OF
THE MEDIUM RANGE OR BEYOND. THE BACKING OFF OF THIS PREDICTED
TRANSPORT HAS NOT BEEN VERY PREPOSSESSING IN TERMS OF CONFIDENCE
IN THE EVENT. STILL, FEEL THERE IS CURRENTLY ENOUGH CRITICAL MASS
IN THE GUIDANCE TO INTRODUCE SIGNIFICANT NEGATIVE TEMPERATURE
ANOMALIES OVER THE NORTH CENTRAL STATES DAYS 6 AND 7 IN THIS
FORECAST PACKAGE.


CISCO
 

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From Mount Holly: Looks like they're expecting wintry weather Somerset County N and W.

 

SUSSEX-WARREN-MORRIS-HUNTERDON-SOMERSET-CARBON-MONROE-BERKS-LEHIGH-
NORTHAMPTON-WESTERN CHESTER-WESTERN MONTGOMERY-UPPER BUCKS-
422 PM EST MON JAN 14 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHERN NEW
JERSEY...NORTHWEST NEW JERSEY...EAST CENTRAL
PENNSYLVANIA...NORTHEAST PENNSYLVANIA AND SOUTHEAST PENNSYLVANIA.

.DAY ONE...TONIGHT.

WIDESPREAD HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

ADVISORY SNOW AND ICE IS EXPECTED LATE TUESDAY NIGHT AND WEDNESDAY
MORNING AS A 6 TO 12 HOUR BURST OF MIXED PRECIPITATION OCCURS. FOR
NOW WE THINK THE SIGNIFICANT SNOW ACCUMULATION WILL REMAIN NORTH
OF I80 WHERE 2 TO 5 INCHES COULD ACCUMULATE WITH NASTY WEDNESDAY
MORNING COMMUTE.


FURTHER SOUTH NEAR INTERSTATE 78 FROM NORTH CENTRAL NEW JERSEY AND
THE LEHIGH VALLEY OF EASTERN PENNSYLVANIA
...DOWN INTO PHILADELPHIA`S
DISTANT WESTERN SUBURBS...PRECIPITATION SHOULD BE A MIX OF SLEET...
RAIN AND FREEZING RAIN...POSSIBLY CHANGING BRIEFLY TO SNOW DURING
THE HEAVIEST PORTION OF THE EVENT EARLY WEDNESDAY MORNING
. ROAD
TREATMENTS ARE ANTICIPATED THERE AS WELL.

THE TRANSITION ZONE OF SNOW ICE AND RAIN IS SUBJECT TO ADJUSTMENT
IN FUTURE FORECASTS.

CONFIDENCE ON A HAZARDOUS WEATHER OCCURRENCE BY DAWN WEDNESDAY IS
ABOVE
AVERAGE IN MUCH OF THIS AREA BUT THE AMOUNTS OF SNOW AND ICE IN ANY
LOCATION IS UNCERTAIN.
 

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The 18z GFS ensembles have a couple of interesting looking possibilities. One looks very similar in strength and placement to the Euro Control run of this morning, although just a touch further east, with a 976 mb low off the DelMarva that it deepens to 956 mb by around Maine or Nova Scotia, really can't even see it. Definite possibilities here.

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would not be a surprise if this continues to trend north to the point where mixing is an issue here - and areas south of the metro are a mix to rain - southeast ridge is not going to give up easily will keep pumping systems more north as we get closer to them in fact next weeks arctic outbreak will not be as deep into the southeast as presently indicated ............

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would not be a surprise if this continues to trend north to the point where mixing is an issue here - and areas south of the metro are a mix to rain - southeast ridge is not going to give up easily will keep pumping systems more north as we get closer to them in fact next weeks arctic outbreak will not be as deep into the southeast as presently indicated ............

It actually trended very much south from this morning. On this morning's run it was so far north of us that it was rain. Now it misses us to the south. This was a major south trend, which will definitely continue. No other model has the storm this far north and the extended NAM is not going to be the one that ends up being correct with this storm. Yes, if it does happen I will eat crow, but I see about zero chance that this is the odd model that will win on the Friday storm.

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It actually trended very much south from this morning. On this morning's run it was so far north of us that it was rain. Now it misses us to the south. This was a major south trend, which will definitely continue. No other model has the storm this far north and the extended NAM is not going to be the one that ends up being correct with this storm. Yes, if it does happen I will eat crow, but I see about zero chance that this is the odd model that will win on the Friday storm.

you know something the models have not been handling anything well - this arctic outbreak keeps getting delayed and positioning of it changed even the latest HPC statement mentions this............

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