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PHL CWA JAN 26/27 OBS and Discussion Thread


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What is the European CONTROL model? JB used it in his video today to show the track and why the storm will be further west than most guidance is showing

FWIW he is up snow amounts from DC to NYC to 6-12, but heaviest axis will still be west of I-95 though he hasn't outlined that axis yet there he did say amounts up to 15" he said he is not upping the snow amounts in the big cities based on track but on precipitation rate.

He's referring to the operational, and he's essentially saying that the CCB will be hammering the big cities, and even though they lose out on some QPF early due to mixing issues and borderline temps, they make up for it with heavier snowfall rates in the CCB and banding features. He's also saying that even this won't make up for the ratios north and west of the cities.

IMHO, if the EC comes in west of the 12Z GFS, the big cities are in big trouble wrt accumulating snow. The GFS pumps warm air in advance of the storm, and as I posted earlier, the 0C line at H85 gets clear to New Hope, PA, and any further westward jog of a potent storm will flood the area with WAA. Not a good scenario for snow along I-95.

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He's referring to the operational, and he's essentially saying that the CCB will be hammering the big cities, and even though they lose out on some QPF early due to mixing issues and borderline temps, they make up for it with heavier snowfall rates in the CCB and banding features. He's also saying that even this won't make up for the ratios north and west of the cities.

IMHO, if the EC comes in west of the 12Z GFS, the big cities are in big trouble wrt accumulating snow. The GFS pumps warm air in advance of the storm, and as I posted earlier, the 0C line at H85 gets clear to New Hope, PA, and any further westward jog of a potent storm will flood the area with WAA. Not a good scenario for snow along I-95.

Good point. Walking a fine line.

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He's referring to the operational, and he's essentially saying that the CCB will be hammering the big cities, and even though they lose out on some QPF early due to mixing issues and borderline temps, they make up for it with heavier snowfall rates in the CCB and banding features. He's also saying that even this won't make up for the ratios north and west of the cities.

IMHO, if the EC comes in west of the 12Z GFS, the big cities are in big trouble wrt accumulating snow. The GFS pumps warm air in advance of the storm, and as I posted earlier, the 0C line at H85 gets clear to New Hope, PA, and any further westward jog of a potent storm will flood the area with WAA. Not a good scenario for snow along I-95.

Thanks I was just very confused as he kept calling the model the control, and he usually just refers to it as the euro or the euro operational

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URGENT - WINTER WEATHER MESSAGE

NATIONAL WEATHER SERVICE MOUNT HOLLY NJ

1120 AM EST TUE JAN 25 2011

...SIGNIFICANT SNOW ACCUMULATION POSSIBLE WEDNESDAY AND ESPECIALLY

EARLY WEDNESDAY NIGHT...

NJZ001-007>010-PAZ054-055-060>062-068-069-252300-

/O.EXT.KPHI.WS.A.0003.110126T1000Z-110127T1200Z/

SUSSEX-WARREN-MORRIS-HUNTERDON-SOMERSET-CARBON-MONROE-BERKS-

LEHIGH-NORTHAMPTON-MONTGOMERY-BUCKS-

INCLUDING THE CITIES OF...NEWTON...WASHINGTON...MORRISTOWN...

FLEMINGTON...SOMERVILLE...JIM THORPE...STROUDSBURG...READING...

ALLENTOWN...BETHLEHEM...EASTON...NORRISTOWN...DOYLESTOWN

1120 AM EST TUE JAN 25 2011

...WINTER STORM WATCH NOW IN EFFECT FROM LATE TONIGHT THROUGH

THURSDAY MORNING...

THE WINTER STORM WATCH IS NOW IN EFFECT FROM LATE TONIGHT THROUGH

THURSDAY MORNING.

* PRECIPITATION TYPE: SNOW...WITH ONLY A BRIEF PERIOD OF ANY SLEET

AND FREEZING RAIN WEDNESDAY AFTERNOON.

* ACCUMULATIONS: 6 INCHES OR MORE OF SNOW...WITH POSSIBLY A

COATING OF ICE POSSIBLE EMBEDDED IN THE EVENT...DURING THE

DAYLIGHT HOURS.

* TIMING: SNOW WILL PROBABLY BEGIN BETWEEN 8 AM AND NOON...WITH

THE HEAVIEST SNOW EXPECTED BETWEEN 5 PM AND MIDNIGHT.

* IMPACTS: THE WEDNESDAY EVENING COMMUTE SHOULD BE AFFECTED AS

ACCUMULATING SNOW FALLS. THE THURSDAY MORNING COMMUTE COULD ALSO

BE AFFECTED BECAUSE OF RESIDUAL CLEANUP OF WEDNESDAYS SNOWFALL.

* CONFIDENCE: CONFIDENCE ON SNOWFALL AMOUNTS AT OR ABOVE 6 INCHES

IN THE POCONOS AND FAR NORTHWEST NEW JERSEY IS A LITTLE LESS

THAN YESTERDAY DUE TO A SOUTHEASTWARD SHIFT IN STORM EVOLUTION.

CONFIDENCE FROM ALLENTOWN TO TRENTON FOR A SUBSTANTIAL WINTER

EVENT IS ABOVE AVERAGE.

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.

&&

$$

DRAG

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Don't know if this was posted. WSW posted for entire Mt Holly area except far SE now.

Feel free to chime in guys if I'm off base:

I think they're going with a compromise of the GFS and the NAM, more GFS than NAM. The NAM still has accumulating snow falling at 7AM Thursday, while in the text of the Watch, they say that it's ending by midnight. They're going with the dynamics of the NAM with the speed and temp profiles of the GFS, and I don't blame them one bit for doing that.

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posted this on another forum, I'll also throw it out here.

The 500 low details seem almost impossible to nail down...shifting where it closes off, when, if it closes off completely and stays closed, or starts to close off then opens back up before finally closing off again just off the coast depending on which model and which run....with big implications for where in the megalopolis the defo band goes most ape****. I will say that the models seem to have gotten better picking up on the general signal and viability of such features compared to say 10+ years ago...but still hair pullingly ambiguous on nailing down where within the broader region of the potential to focus. A couple weeks ago(?) they picked up brilliantly that there would be a narrow band of intense snowfall somewhere from NE Nj to Mass...with several runs of NAM and some of the mesos identifying central Conn as the target zone..but none ever fixing on it for more than one run, where that mega band eventually did set up.

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Mt Holly AFD

SHORT TERM /8 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...

-- Changed Discussion --***WATCH EXPANSION INTO NE MD...N DEL AND MUCH OF NJ IS POSTED***

WILL ADJUST WX GRIDS AND SNOWFALL MAP BY 1215 PM. TOPDOWN METHOD.

SAW THE NEW 12Z NAM WITH HUGE SNOWGROWTH AND QPF AMTS UNDER THE

DEFORMATION ZONE NW OF THE NAMS MORE DEFINED 500MB STRUCTURE.

COULD BE THUNDER SNOW WED EVE.

COLLAB WITH HPC AT 8AM REGARDING MY UNCERTAINTY FURTHER NW IN NE

PA AND NW NJ BUT AWAITING ALL THE MODELS BEFORE ANY POSSIBLE TRIM

THERE. FOCUS "MAY" BE SHIFTING SEWD 30 MILES.

I JUST DONT KNOW HOW PERSISTENT THE PCPN WEDNESDAY.

COULD BE ONE OF THOSE DAYS WITH JUST A TAD OF HAZARDOUS SLEET/SNOW/FREEZING

RAIN IN THE 4 AM TO 10 AM TIME FRAME THEN NO PROBLEM TIL MID OR

LATE AFTERNOON?

PRECIPITATION SHOULD PROGRESS NORTH INTO THE DRIER AIR WEDNESDAY...

MAKING IT INTO THE NORTHERN ZONES BY LATE WEDNESDAY AFTERNOON. BASED

ON THE 850 MB LOW TRACK...IT WOULD APPEAR AS THOUGH MOST OF SOUTHERN

AND CENTRAL NEW JERSEY...NORTHEAST MARYLAND AND DELAWARE WOULD BE

WARMING TO THE POINT WHERE SNOWFLAKE PRODUCTION WOULD BECOME

DIFFICULT FOR A TIME WEDNESDAY.

IN THESE AREAS...A MAINLY RAIN EVENT IS EXPECTED FOR THE DAY

WEDNESDAY. AS PRECIPITABLE WATER VALUES APPROACH ONE INCH NEAR KACY

WEDNESDAY AFTERNOON (WHICH IS 2 STANDARD DEVIATIONS ABOVE NORMAL)...

HEAVY RAIN BECOMES POSSIBLE. THIS MAY NOT BE MENTIONED YET AS ONLY

NUISANCE FLOODING WOULD BE EXPECTED.

FURTHER NORTHWEST...THE COLUMN STARTS COLD ENOUGH FOR SNOW...BUT ALL

MODELS ARE SHOWING A WARM LAYER AROUND 6000 FEET...WHICH COULD

RESULT IN SLEET AS WELL. SO...FOR THE DAY WEDNESDAY...MOST OF THE

QPF NORTH AND WEST OF PHILADELPHIA COULD FALL IN THE FORM OF SNOW

AND SLEET. AT THIS JUNCTURE...THE SNOW AND SLEET AMOUNTS WOULD LOOK

TO BE LESS THAN 4 INCHES THROUGH DUSK WEDNESDAY.

THE ABOVE DOES CONTAIN SOME UNCERTAINTY...AS INDIVIDUAL OPERATIONAL

RUNS SHOW A SIGNIFICANT SPREAD IN THE AMOUNT OF LOW LEVEL WARMING.

BECAUSE OF THIS...A BLENDED APPROACH WAS USED FOR HIGH TEMPERATURES

WEDNESDAY.

THE EVENT STARTS TO BECOME MORE INTERESTING LATE WEDNESDAY INTO

WEDNESDAY NIGHT. AS THE MID LEVEL CLOSED LOW APPROACHES THE AREA...

A COUPLE OF THINGS HAPPEN. FIRST...THE COLUMN ITSELF GETS COLDER DUE

TO DYNAMIC COOLING. BASED ON A BLEND APPROACH TO THE COLUMN

TEMPERATURE PROFILES...THIS COULD BE ENOUGH FOR AREAS SEEING RAIN TO

CHANGE TO SNOW DURING THE EVENING ACROSS NORTHEAST MARYLAND...

NORTHERN DELAWARE...AS WELL AS SOUTHWEST AND CENTRAL NEW JERSEY,

COULD BE THUNDER SNOW AND 1 TO 2 INCH PER HOUR SNOWFALL RATES FOR

SEVERAL HOURS WITHIN 30 MI EITHER SIDE OF I95.

WINDS WILL INCREASE AS THE SURFACE LOW APPROACHES WEDNESDAY

AFTERNOON. MODEL SOUNDINGS SUGGEST 35 TO 40 KNOTS OF WIND WILL BE

AVAILABLE AT THE TOP OF THE INVERSION AS THE SURFACE LOW GETS GOING.

FOR NOW...WILL INDICATE THE POTENTIAL FOR WINDS TO GUST TO 35 TO 40

MPH...BUT IT IS TOO EARLY TO CONSIDER WIND HEADLINES AT THIS TIME.

THURSDAY SHOULD BE QUIETER...WITH BREEZY CONDITIONS IN THE

MORNING.-- End Changed Discussion --

&&

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He's referring to the operational, and he's essentially saying that the CCB will be hammering the big cities, and even though they lose out on some QPF early due to mixing issues and borderline temps, they make up for it with heavier snowfall rates in the CCB and banding features. He's also saying that even this won't make up for the ratios north and west of the cities.

IMHO, if the EC comes in west of the 12Z GFS, the big cities are in big trouble wrt accumulating snow. The GFS pumps warm air in advance of the storm, and as I posted earlier, the 0C line at H85 gets clear to New Hope, PA, and any further westward jog of a potent storm will flood the area with WAA. Not a good scenario for snow along I-95.

Further west track brings in more QPF and warmer temps. As long as there is heavy precip on back end I-95 will do OK even if first part of storm is rain or mix.

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Mt Holly AFD

SHORT TERM /8 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...

-- Changed Discussion --***WATCH EXPANSION INTO NE MD...N DEL AND MUCH OF NJ IS POSTED***

WILL ADJUST WX GRIDS AND SNOWFALL MAP BY 1215 PM. TOPDOWN METHOD.

SAW THE NEW 12Z NAM WITH HUGE SNOWGROWTH AND QPF AMTS UNDER THE

DEFORMATION ZONE NW OF THE NAMS MORE DEFINED 500MB STRUCTURE.

COULD BE THUNDER SNOW WED EVE.

COLLAB WITH HPC AT 8AM REGARDING MY UNCERTAINTY FURTHER NW IN NE

PA AND NW NJ BUT AWAITING ALL THE MODELS BEFORE ANY POSSIBLE TRIM

THERE. FOCUS "MAY" BE SHIFTING SEWD 30 MILES.

I JUST DONT KNOW HOW PERSISTENT THE PCPN WEDNESDAY.

COULD BE ONE OF THOSE DAYS WITH JUST A TAD OF HAZARDOUS SLEET/SNOW/FREEZING

RAIN IN THE 4 AM TO 10 AM TIME FRAME THEN NO PROBLEM TIL MID OR

LATE AFTERNOON?

PRECIPITATION SHOULD PROGRESS NORTH INTO THE DRIER AIR WEDNESDAY...

MAKING IT INTO THE NORTHERN ZONES BY LATE WEDNESDAY AFTERNOON. BASED

ON THE 850 MB LOW TRACK...IT WOULD APPEAR AS THOUGH MOST OF SOUTHERN

AND CENTRAL NEW JERSEY...NORTHEAST MARYLAND AND DELAWARE WOULD BE

WARMING TO THE POINT WHERE SNOWFLAKE PRODUCTION WOULD BECOME

DIFFICULT FOR A TIME WEDNESDAY.

IN THESE AREAS...A MAINLY RAIN EVENT IS EXPECTED FOR THE DAY

WEDNESDAY. AS PRECIPITABLE WATER VALUES APPROACH ONE INCH NEAR KACY

WEDNESDAY AFTERNOON (WHICH IS 2 STANDARD DEVIATIONS ABOVE NORMAL)...

HEAVY RAIN BECOMES POSSIBLE. THIS MAY NOT BE MENTIONED YET AS ONLY

NUISANCE FLOODING WOULD BE EXPECTED.

FURTHER NORTHWEST...THE COLUMN STARTS COLD ENOUGH FOR SNOW...BUT ALL

MODELS ARE SHOWING A WARM LAYER AROUND 6000 FEET...WHICH COULD

RESULT IN SLEET AS WELL. SO...FOR THE DAY WEDNESDAY...MOST OF THE

QPF NORTH AND WEST OF PHILADELPHIA COULD FALL IN THE FORM OF SNOW

AND SLEET. AT THIS JUNCTURE...THE SNOW AND SLEET AMOUNTS WOULD LOOK

TO BE LESS THAN 4 INCHES THROUGH DUSK WEDNESDAY.

THE ABOVE DOES CONTAIN SOME UNCERTAINTY...AS INDIVIDUAL OPERATIONAL

RUNS SHOW A SIGNIFICANT SPREAD IN THE AMOUNT OF LOW LEVEL WARMING.

BECAUSE OF THIS...A BLENDED APPROACH WAS USED FOR HIGH TEMPERATURES

WEDNESDAY.

THE EVENT STARTS TO BECOME MORE INTERESTING LATE WEDNESDAY INTO

WEDNESDAY NIGHT. AS THE MID LEVEL CLOSED LOW APPROACHES THE AREA...

A COUPLE OF THINGS HAPPEN. FIRST...THE COLUMN ITSELF GETS COLDER DUE

TO DYNAMIC COOLING. BASED ON A BLEND APPROACH TO THE COLUMN

TEMPERATURE PROFILES...THIS COULD BE ENOUGH FOR AREAS SEEING RAIN TO

CHANGE TO SNOW DURING THE EVENING ACROSS NORTHEAST MARYLAND...

NORTHERN DELAWARE...AS WELL AS SOUTHWEST AND CENTRAL NEW JERSEY,

COULD BE THUNDER SNOW AND 1 TO 2 INCH PER HOUR SNOWFALL RATES FOR

SEVERAL HOURS WITHIN 30 MI EITHER SIDE OF I95.

WINDS WILL INCREASE AS THE SURFACE LOW APPROACHES WEDNESDAY

AFTERNOON. MODEL SOUNDINGS SUGGEST 35 TO 40 KNOTS OF WIND WILL BE

AVAILABLE AT THE TOP OF THE INVERSION AS THE SURFACE LOW GETS GOING.

FOR NOW...WILL INDICATE THE POTENTIAL FOR WINDS TO GUST TO 35 TO 40

MPH...BUT IT IS TOO EARLY TO CONSIDER WIND HEADLINES AT THIS TIME.

THURSDAY SHOULD BE QUIETER...WITH BREEZY CONDITIONS IN THE

MORNING.-- End Changed Discussion --

&&

Walt Drag is awesome!

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Further west track brings in more QPF and warmer temps. As long as there is heavy precip on back end I-95 will do OK even if first part of storm is rain or mix.

How often do the back end snows work out in this area? Trust me, if that storm moves west of the 12Z GFS guidance, PHL is way more rain than snow, and any snow that falls will have a massively difficult time accumulating. That will cause more ice than anything else, and that wouldn't be very enjoyable.

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Walt Drag is awesome!

Given the fact that the AFD was a half hour late, the zones and the maps havent been updated yet, they must be busy as all hell. I'd like to be a fly on the wall there today. And your right, Walt's narratives are great (I think they all do a great job though with that).

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Given the fact that the AFD was a half hour late, the zones and the maps havent been updated yet, they must be busy as all hell. I'd like to be a fly on the wall there today. And your right, Walt's narratives are great (I think they all do a great job though with that).

Yeah, things must be crazy. But at least with Walt (and many others down there as you mentioned), you kinow you're getting full effort.

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Has anyone noticed how much moisture is being fed into this storm from the GOM? This is a much different look from the previous storms this season.

Yes. And that's why if I lived in the LV or Poconos, I wouldn't jump off a bridge just yet. Sure, the highest QPF may be I-95 on SE, but I think they're going to do quite well up there.

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Yes. And that's why if I lived in the LV or Poconos, I wouldn't jump off a bridge just yet. Sure, the highest QPF may be I-95 on SE, but I think they're going to do quite well up there.

Yes, those west of I-95 back to I-81 still have a chance for an overperforming CCB plus the chance of initial snow that may fall as rain east of I-95 a la 12Z GFS. Watching closely.

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