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NYC/PHL Jan 18-19 Potential Threat Thread


am19psu

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Mt Holly by DRAG

ESSENTIALLY THEN FROM S TO N A TRACE TO 4 INCH EVENT....BULK OF FCSTAREA 1-3 INCHES IN SEVERAL HOURS LATE MONDAY EVENING OR TUESDAY MORNINGFOLLOWED BY A QUICK TRANSITION TO RAIN I95 EWD WITH MAYBE AN HR OR2 OF FREEZING RAIN...BUT DO REMEMBER THE GROUND IS FROZEN SO ANYCLEARING OF THE SNOW PRIOR TO TRANSITION TO RAIN MAY PERMIT A AGREATER CHANCE OF UNTREATED ICY PAVEMENTS FOR A COUPLE OF HRSTUESDAY MORNING

.FREEZING RAIN ICING AMOUNTS... GENERALLY LESS THAN 0.20 IN NE PAAND NW NJ THIS EVENT. PLAYED IT CONSERVATIVE AS TEMPS MAY RISEFASTER THAN INDICATED. BELOW AVG CONFIDENCE ON THE OUTPUT OF THEICE ACCUM TOOL.

00Z/16 NAM DID NOT LOOK REALISTIC...FAR TOO SLOW AND THEN EVENTUALLYLOOKS TOO WRAPPED UP ONTO ITSELF AS IT EVOLVES LOW PRES OFF THECOAST. 00Z GFS WAS USED AS THE PRIMARY FORECAST GUIDANCE FROMMIDDAY MONDAY ONWARD /NO 00Z NAM NOR THE RATHER WARM 00Z/16 ECMWF

GFS/ECMWF HAVE BEEN CONSISTENT FOR SEVERAL MODEL CYCLES BUTTHE ECMWF HAS BEEN MUCH WARMER.

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Mt Holly by DRAG

ESSENTIALLY THEN FROM S TO N A TRACE TO 4 INCH EVENT....BULK OF FCSTAREA 1-3 INCHES IN SEVERAL HOURS LATE MONDAY EVENING OR TUESDAY MORNINGFOLLOWED BY A QUICK TRANSITION TO RAIN I95 EWD WITH MAYBE AN HR OR2 OF FREEZING RAIN...BUT DO REMEMBER THE GROUND IS FROZEN SO ANYCLEARING OF THE SNOW PRIOR TO TRANSITION TO RAIN MAY PERMIT A AGREATER CHANCE OF UNTREATED ICY PAVEMENTS FOR A COUPLE OF HRSTUESDAY MORNING

.FREEZING RAIN ICING AMOUNTS... GENERALLY LESS THAN 0.20 IN NE PAAND NW NJ THIS EVENT. PLAYED IT CONSERVATIVE AS TEMPS MAY RISEFASTER THAN INDICATED. BELOW AVG CONFIDENCE ON THE OUTPUT OF THEICE ACCUM TOOL.

00Z/16 NAM DID NOT LOOK REALISTIC...FAR TOO SLOW AND THEN EVENTUALLYLOOKS TOO WRAPPED UP ONTO ITSELF AS IT EVOLVES LOW PRES OFF THECOAST. 00Z GFS WAS USED AS THE PRIMARY FORECAST GUIDANCE FROMMIDDAY MONDAY ONWARD /NO 00Z NAM NOR THE RATHER WARM 00Z/16 ECMWF

GFS/ECMWF HAVE BEEN CONSISTENT FOR SEVERAL MODEL CYCLES BUTTHE ECMWF HAS BEEN MUCH WARMER.

I like the part of his discussion I highlighted in red. Experience has shown me that it's difficult to maintain an icy scenario in the Lehigh Valley and lower elevations. It usually seems that the warm air wins out and a major ice storm is averted, even here in Tamaqua, which is 500 ft higher than the Valley and surrounding areas. Places that HAVE stayed cold enough and have had major ice storms has been the I-81 ridgetop, McAdoo, and some areas of the Poconos.

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As I have detailed before from the KU book....Philly in reality does very well with Miller B storms. Now BWI area....not so much.

Miller A's are easier to predict, because they already exist, and they are likely to be a more sure "hit". However, Miller B's usually have a higher chance of being all snow. NYC area can cash in from both scenarios. From PHL South, I would MUCH rather have a Miller A.

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As I have detailed before from the KU book....Philly in reality does very well with Miller B storms. Now BWI area....not so much.

Drag also forecasts for MT Holly ? Anyways Tuesday morning has a good chance of being a traffic nightmare especially the further you go north through central NJ especially from I95 NJ Turnpike and west and this not at all set in stone when the changeover to plain rain will actually be ...

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Ice Storm update for the NW Philadelphia Suburbs

per Wxsim module based off 6z GFS and NAM

Snow starts around midnight tomorrow night temp at 23.8

Moderate snow by 3am with 1-2" of Snow by 6am

IP/SN mix by 6am with a transition to ZR by 9am

ZR continues till 11:30am when temps finally get above freezing. Total precip to this point is 0.95" (all frozen or ZR)

Rain then till ending toward midnight

Tuesday AM rush...will not be pleasant

Stay safe

Paul

www.chescowx.com

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Walt is now a member of the Mt Holly team

Drag also forecasts for MT Holly ? Anyways Tuesday morning has a good chance of being a traffic nightmare especially the further you go north through central NJ especially from I95 NJ Turnpike and west and this not at all set in stone when the changeover to plain rain will actually be ...

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Walt is now a member of the Mt Holly team

Should see some improvement down there with Drag on the team. Also lower Level cold air is going to be a little harder to overcome than most models show IMO, especially if the low remains off the coast. With a good snow pack over most of the NE and SNE, bl temps will likely stay colder than any model is currently compensating for - and the one or 2 degree compensation is extremely critical during this event and there is an above normal bust possibility ....

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Should see some improvement down there with Drag on the team. Also lower Level cold air is going to be a little harder to overcome than most models show IMO, especially if the low remains off the coast. With a good snow pack over most of the NE and SNE, bl temps will likely stay colder than any model is currently compensating for - and the one or 2 degree compensation is extremely critical during this event and there is an above normal bust possibility ....

I wouldn't say improvement as much as I'd say a great addition to an already stellar office

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When you take a look at the HPC charts it makes me scratch my head. They have pushed the threat zone of > 4" of snow completely out of NJ and have lowered the probabilities even up into NE. Then, they expanded the freezing rain threat NE but again have pushed it out of NJ. The QPF map doesnt look imressive either considering their is heavy QPF modeled to be over the area at times. So basically, they are completely discounting the snow/ice threat for the I-95 corridor and more or less think we end up with slush. I understand the reasoning behind a conservative forecast but several model runs have shown a major ice storm for the I-95 corridor, especially north and west and it looks like those models are being discounted. When you look at the forecast lows for monday night, the position/strength of the high and with the snow pack, its hard to believe were going to get out of the low to mid 30's for highs.

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When you take a look at the HPC charts it makes me scratch my head. They have pushed the threat zone of > 4" of snow completely out of NJ and have lowered the probabilities even up into NE. Then, they expanded the freezing rain threat NE but again have pushed it out of NJ. The QPF map doesnt look imressive either considering their is heavy QPF modeled to be over the area at times. So basically, they are completely discounting the snow/ice threat for the I-95 corridor and more or less think we end up with slush. I understand the reasoning behind a conservative forecast but several model runs have shown a major ice storm for the I-95 corridor, especially north and west and it looks like those models are being discounted. When you look at the forecast lows for monday night, the position/strength of the high and with the snow pack, its hard to believe were going to get out of the low to mid 30's for highs.

It's not easy to get an ice storm in NYC metro. Even in 2008 that crazy icestorm was a high elevation sussex co event. Rest of us had ice, but nothing out of the ordinary.

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Actually the addition of Walt just adds to an all star team...kind of like the Phillies adding Cliff Lee...Go Phils!

Weather wise I agree the snowpack that is in place for the Philly/NYC burbs will cause a difference. I actually ran my Wxsim module without the current snowcover to see the impact on the forecast. It resulted in an average 1 to 2 degree difference. And as we all know that can be a huge difference. Any way you slice it it appears to be very tricky early morning commute on Tuesday

Should see some improvement down there with Drag on the team. Also lower Level cold air is going to be a little harder to overcome than most models show IMO, especially if the low remains off the coast. With a good snow pack over most of the NE and SNE, bl temps will likely stay colder than any model is currently compensating for - and the one or 2 degree compensation is extremely critical during this event and there is an above normal bust possibility ....

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It's not easy to get an ice storm in NYC metro. Even in 2008 that crazy icestorm was a high elevation sussex co event. Rest of us had ice, but nothing out of the ordinary.

The probability of such an even verifying shouldnt play a role when multiple models inside 72 hrs, which are probably not taking into account the snowpack are depicting major ice. In 2008, I was in Ramsey, (NE Bergen County) and we had significant ice. In fact, we were upgraded to an ice storm warning about half way through the event. It sticks out in my head because Its the only time I remember ever being in a county with an ice storm warning. The trees/cars were covered and it was quite a site.

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The probability of such an even verifying shouldnt play a role when multiple models inside 72 hrs, which are probably not taking into account the snowpack are depicting major ice. In 2008, I was in Ramsey, (NE Bergen County) and we had significant ice. In fact, we were upgraded to an ice storm warning about half way through the event. It sticks out in my head because Its the only time I remember ever being in a county with an ice storm warning. The trees/cars were covered and it was quite a site.

I see your point, but the models haven't exactly endeared themselves to forecast confidence this year.

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It's not going to snow 12 inches with every storm. We have the potential here for a major winter storm and a very icy one at that and I for one am very excited. Snow lovers only have a week to wait.

agreed...I came to this thread looking for a lot of posts and analysis but not finding much. Its like no one cares about a potential 1-3 incher followed by ice and then cold rain. Its still a decent interesting winter event to track when there is cad. Not sure why everyone has passed on this one. It most certainly will not be snowing a foot every storm and people will probably learn the hard way going forward

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Actually the addition of Walt just adds to an all star team...kind of like the Phillies adding Cliff Lee...Go Phils!

Weather wise I agree the snowpack that is in place for the Philly/NYC burbs will cause a difference. I actually ran my Wxsim module without the current snowcover to see the impact on the forecast. It resulted in an average 1 to 2 degree difference. And as we all know that can be a huge difference. Any way you slice it it appears to be very tricky early morning commute on Tuesday

wait, Walt Drag is not in SNE any longer?

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Current point and click forecast for my location:

Monday Night: Snow, mainly after 9pm. Low around 19. East wind between 3 and 10 mph. Chance of precipitation is 100%.

Tuesday: Snow and freezing rain, possibly mixed with sleet before 3pm, then rain or freezing rain likely between 3pm and 4pm, then freezing rain likely after 4pm. High near 32. East wind between 6 and 11 mph. Chance of precipitation is 100%. New precipitation amounts between a quarter and half of an inch possible.

Tuesday Night: Freezing rain likely before 3am, then a chance of snow. Cloudy, with a low around 29. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

For Bethlehem area in the LV:

Monday Night: Snow, mainly after 9pm. Low around 21. Calm wind becoming northeast between 6 and 9 mph. Chance of precipitation is 100%.

Tuesday: Snow and freezing rain before 11am, then rain or freezing rain between 11am and 1pm, then rain likely after 1pm. High near 34. East wind between 5 and 10 mph. Chance of precipitation is 100%. New precipitation amounts between a quarter and half of an inch possible.

Tuesday Night: A chance of rain before midnight, then a chance of freezing rain. Cloudy, with a low around 31. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch possible.

Not sure if anyone posted this from the AFD this morning:

IF THERE IS A SIGNIFICANT ICING PROBLEM IT APPEARS CONFINED TO

THE NW 1/4 OF NJ INTO NE PA VCNTY KABE TO K12N NWWD AND AMOUNTS

OF FREEZING RAIN SHOULD BE UNDER 1/4 INCH BUT THERE IS ROOM FOR

GREATER AMOUNTS. JUST CANT BE SURE OF THE AXIS OF HEAVIEST PCPN

COINCIDING WITH BELOW FREEZING TEMPS AND RESULTANT ICE.

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