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March 24-25 Potential Bomb Part Deux


earthlight

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Of course hugging a model is wrong, but trying to find ways why the better model is wrong by using a case on Jan 2011....is just awful logic.

Completely agree with your logic about weenies cherrypicking single examples of poor Euro performance being statistically insignificant, and, hence, flawed logic.  Having said that, though, it would be nice to have more of a data-driven comparison of models.  We all know that overall verification scores are better for the Euro, but what we don't know (or at least I'm unaware of) is whether the Euro's performance advantage extends into specific situations, such as east coast snowstorms, or of even more relevance, results in the Philly-NYC corridor for Miller B's with coastal cyclogenesis and strong confluence from the north - I'm guessing, though, that we might not have a sample size of similar situations that is statistically large enough for the latter. 

 

Anyway, despite the overall verification scores and the general perception that the Euro is better, it's at least interesting to see what the esteemed Walt Drag said in his 3/5 AFD:  "TO PREFACE THE DIRECTION WE ARE GOING... THE ECMWF HAS GENERALLY NOT BEEN STELLAR INSIDE OF DAY 5...SINCE THE SANDY EVENT FOR OUR AREA... AND IN MY OPINION...AT LEAST FOR THIS AREA...THE GFS AND ITS ENSEMBLES AS WELL AS THE SREF ARE BETTER PREDICTORS FOR OUR WEATHER..."  He didn't include any data to back this up, but presumably he had some.  Thoughts? 

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This thread is really pathetic this afternoon and it makes myself (and I'm sure other moderators too) dissappointed since we tried to reshuffle things in here this winter and there's still a pinned thread sitting at the top of the forum explaining the rules.

I don't have the time to be here every day (like today), but some of you just seem like you will never be able to understand the concept of quality discussion. That will only force us to have a strict moderation, people will get banned, and the "fun" on the forum will essentially end.

So do as you wish.

 

Probably the last major snow possibility this season.  In a few days the forums will be dead.  Please give the guys some slack and let them vent.

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The euro has been great for sne this winter, but it has been less then stellar around the Phl and Ttn area.

It will be interesting to see if the euro is lock in or drops the ball.

My call would be 1-3 city 2-4 central nj 3-6 outside Phl into elevation with perhaps more.

Def high bust potential either way

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what's so tough about it? every model keeps the best snows south.

agreed, but there are still differences as to how much snow gets into the area.  plus the issue of how much accumulates.....as i said in my post, i think 2-4 is somewhat bullish,esp. given the euro.

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just enough...to ALMOST get in line with the more correct models

To say they are "correct" at this point is to imply the storm has already happened... Which you couldn't possibly know how it will turn out exactly... Unless you can see the future... Can you? If the NAM crushes the area but is 20 miles too far north and the Euro misses the area but is 20 miles too far south and the real solution is right in the middle but with no precipitation entering the region, did the EURO win? Not really. Lets wait and see what verifies before crowning champions for this particular storm, although granted the EURO is FAR superior to our models

At this point for this region it is looking as though the worst of the storm will pass off to the south of the region based on model data. that being said models (AKA guidance, with an emphasis on the GUIDANCE part) are computer programs based on a thorough, yet incomplete, understanding of the atmosphere. They get some right, they get some wrong, and some do either more often than some other models, but can we please stop this bickering over models? It really just degrades the discussion completely

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mount holly

 

 

 

WELL IT WAS TIME TO MAKE A DECISION AND TO BE QUITE HONEST CANT SAYTHAT THIS IS A CONFIDENT ONE WHICH IS PRETTY MUCH THE WAY SNOWFORECASTS HAVE GONE FOR MOST OF THIS WINTER. PLEASE STAY TUNED FORLIKELY UPDATES AND CHANGES TO AMOUNTS AND OR HEADLINES AS THISREMAINS A DIFFICULT FORECAST TO PEG.THE MODELS ARE ALL VERY SIMILAR IN RAPIDLY DEVELOPING A LOW PRESSURESYSTEM OFF OF THE VIRGINIA COAST WHICH WILL CAUSE AN INITIALPRECIPITATION BURST DURING THE MORNING. THE DIFFERENCES COME WITHTHE SECONDARY SURGE DURING THE AFTERNOON AS THE TROWAL DEVELOPS. THENON-US MODELS ARE FARTHER OFFSHORE AND SUPPORT LIGHTER QPF AMOUNTSWHILE THE DOMESTIC MODELS WOULD HIT SOUTHEASTERN/EASTERN NJ PRETTYHARD. THIS IS ALMOST A FLIP IN THE FORECAST WE HAD GOING WITH THEBULK OF THE HEAVIER SNOW NORTH AND WEST OF THE FALL LINE. WE HOPEOUR FLIP IS CORRECT AS WE HAVE INCREASED SNOW AMOUNTS SE OF I95WHILE KEEPING GENERALLY KEEPING SIMILAR AMOUNTS NORTH AND WEST.THE PREDECESSOR AIR MASS IS CONSIDERABLY DRIER THAN THE ONE IN EARLYMARCH THAT GAVE US FCSTING FITS AND WHILE THE PAPARAZZI CHASESDYNAMIC COOLING AROUND, EVAPORATIONAL COOLING WHICH ONLY HAS SOMEPERSON WITH A POLAROID WATCHING IT IS ACTUALLY A MORE EFFECTIVE SNOWPRODUCER.SO FOR TONIGHT WHEN PRECIPITATION INITIALLY STARTS, BOUNDARYTEMPERATURES SHOULD SUPPORT A START AS RAIN AND THEN THE PTYPESHOULD TRANSITION TO SNOW AS EVAPORATIONAL COOLING TAKES HOLD.WHILE THE NAM/WRF-NMMB HAS A COLD BIAS ITS MOS GUIDANCE IS LIKELYCLOSER TO THE CORRECT TEMPERATURE SCENARIO AGAIN AND WAS FOLLOWEDCLOSER.

 

 

 

 

TOMORROW COMES DOWN AS TO WHETHER PRECIPITATION INTENSITY CAN OUTDUELTHE LATE MARCH SUN ANGLE AND POSSIBLY SOME MARGINAL BOUNDARY LAYERCONDITIONS. CONFIDENCE IN SNOW AMOUNTS DECREASE DURING THE SECONDHALF OF THE DAY (NOT THAT THEY ARE HIGH IN THE FIRST HALF) AS THISIS WHEN THE CONFLICT WILL BE PEAKING. IN THE FIRST HALF OF THEDAY, WE HAVE SEEN THE RECENT WRAP AROUND SNOWS ACCUMULATE RATHEREASILY AND EVEN SAW THE 1 INCH SNOWS DO WELL AROUND NOON ALONG THEIMMEDIATE COAST LAST WEEK. SO EVAP COOLING MOST PLACES TO SNOW, WEWOULD ENVISION SOME ROADWAY PROBLEMS FROM RDG TO THE PHL METROAREA SOUTHWEST FOR THE MORNING COMMUTE. ONCE WE REACH THE FALLLINE IT WILL BE DIFFICULT FOR THE PTYPE TO NOT BE SNOW.AS WE GO LATER IN THE MORNING THE RAPID DEEPENING BY LOGIC WOULDSUPPORT AN EXPANDING OF THE PCPN SHIELD AS WELL AS INCREASE IN PCPNINTENSITY. THIS RIGHT NOW EVEN IN SOME OF THE NON US MODEL SOLUTIONSHAS SOUTHEASTERN NJ UNDER THE MOST FAVORABLE LOCATION FORDYNAMICALLY COOLED SNOW OR ACCUMULATING SNOW BECAUSE OF THE GENERALINTENSITY.THE DIFFERENCE COMES IN THE AFTERNOON WHETHER OR NOT ACCUMULATINGSNOW CAN BE ONGOING AS WE WILL NEED THE INTENSITY AS DISPLAYED IN THEU.S. MODELS FOR THIS TO CONTINUE. NORTH AND WEST OF THE FALL LINE WETOOK ABOUT 2/3RDS OF THE NAMS QPF AND APPLIED CLOSE TO A 10:1 RATIOFOR SNOWFALL. ELSEWHERE WE TOOK SIMILAR AMOUNTS OFF, BUT APPLIED ARATIO BETWEEN 5:1 TO 8:1 TO ARRIVE AT OUR SNOWFALL TOTALS. ONCEPRECIPITATION STARTS TO LESSEN DURING THE AFTERNOON, A MIX OR CHANGETO RAIN COULD OCCUR. OBVIOUSLY THE SNOW WILL HAVE AN EASIER TIME OFACCUMULATING ON NON PAVED SURFACES AND DONT KNOW IF WE WILL REACHTHE POINT WHERE SNOW WILL BE A PROBLEM ON TREES AND TREE LIMBS. WEDO CATCH A BREAK THAT NOTHING IS EVEN STARTING TO BLOOM.

http://forecast.weather.gov/product.php?site=NWS&issuedby=PHI&product=AFD&format=CI&version=1&glossary=1&highlight=off

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i think the cutoff will be even sharper than modeled. the confluence is advecting dry air from the north and that enhances the gradient

 

Agree.  Maybe over here it's a few miles broader because of the NE winds up through 700...but it's going to be feast or famine in a 10 mile width tops I think.  10 miles one way someone could get hit pretty hard, 10 miles the other way lucky to see a flurry?

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To say they are "correct" at this point is to imply the storm has already happened... Which you couldn't possibly know how it will turn out exactly... Unless you can see the future... Can you? If the NAM crushes the area but is 20 miles too far north and the Euro misses the area but is 20 miles too far south and the real solution is right in the middle but with no precipitation entering the region, did the EURO win? Not really. Lets wait and see what verifies before crowning champions for this particular storm, although granted the EURO is FAR superior to our models

At this point for this region it is looking as though the worst of the storm will pass off to the south of the region based on model data. that being said models (AKA guidance, with an emphasis on the GUIDANCE part) are computer programs based on a thorough, yet incomplete, understanding of the atmosphere. They get some right, they get some wrong, and some do either more often than some other models, but can we please stop this bickering over models? It really just degrades the discussion completely

 

good post - you are right

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Not that I expect anything at all, but I would wait for the full 0z models suite to come in tonight to have more confidence for where the gradient sets up. It would be nice to have one more round of fresh data.

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