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NYC/PHL: December 24-27th Potential


earthlight

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I am just a forum lurker, I seriously don't know where to post anymore.

I tried to post my thoughts on this storm in the 0Z model thread, but it got buried because the 0Z Euro was coming out. My thoughts on the potential storm. Seems to be a number of schools of thought based off the 0Z thread....I guess this is just one of the many. In short, I find the strength of the eventual PV anomaly in the southern stream the key in how all this plays out, at least based on the evidence thus far.

A lot of interesting discussion and analysis here. I haven't been completely up to date on this one, but doing a quick analysis, it seems the potential for a good east coast hit seems to hinge the most on how the northern stream eventually phases with the PV Anomaly near the Gulf States. The 0Z GFS essentially treats the PV as an "ejecting" S/W trough which incites cyclogenesis ahead of the main trough which develops a strong leading edge cyclone with cold air advection turning towards the east coast as opposed to heading southward towards the GOM. The other solution favored by tonights CMC, the ECMWF, and to a degree, by the 12Z GFS, is to phase the southern PV and "absorb" it into the northern stream which then enhances the strength of CAA southward towards the GOM. This in turn develops a much deeper upper trough and eventually a much more energetic baroclinic wave up the east coast.

One thing I will say regarding the solutions is the amount of CAA all solutions develop in the low levels. It is difficult for equatorward low level cold air to suddenly shift direction and head eastward as in the 0Z GFS. It would take a sufficiently intense PV to initiate strong enough cyclogenesis to result in an eastward displacement of that low level cold air and the eventual northern cyclone the GFS develops. While the 0Z GFS certainly could be a valid solution, I find the deeper trough solutions more realistic given all model guidance have trended towards a much weaker southern stream PV Anomaly. As a result, I find a solution which results in continued CAA and a deeper developing trough more realistic then the oddball northern cyclone the GFS currently has. A weaker PV Anomaly, once phased, won't incite sufficiently strong cyclogenesis to shunt the low level CAA eastward but strong enough to enhance the continued equatorward flow of CAA, thus developing the trough deeper before ejecting the leading wave along the Gulf Stream. In terms of the GFS, the 12Z solutions seems more realistic given the circumstances. That is how I read it, at least.

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what else you gonna do at 445am lol....ill tell you one thing. If we get this snow and we get a clear night with no wind, wowsers, i could see temps in the single digits in the burbs and mid to low teens for the cities

Yes, I think it'll be pretty cold after this storm, definitely some insane negative departures coming to the Mid-Atlantic and Southeast. Let's get a foot of snowpack on the ground and then allow the -15C 850s to move in with hurricane strength NW winds.

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I'm kind of surprised that the AFD from Mount Holly has a not-so-enthused feeling with the potential Christmas bomb, considering the decent 0z suite agreement sans the UMKET.

ONCE AGAIN, ALL EYES ARE FOCUSED ON AN EVENT (OR NON-EVENT) OVER

THE HOLIDAY WEEKEND. THE MODEL GUIDANCE IS ALL OVER THE PLACE AND

HAS ABOUT 6 DAYS TO HOPEFULLY SHAKE ITSELF OUT.

NO CHANGES WERE MADE TO THE 4PM MONDAY KPHI EXTENDED FCST.

THE 00Z/21 42 MEMBER NAEFS /GFS-GGEM/ TRENDS ARE STILL OFFSHORE

WITH A GLANCING BLOW...IF ANY. MEANWHILE THE 00Z/21 OPERATIONAL

ECMWF TRYING TO LOCK IN NEAR THE COAST BUT ECMWF OP PERFORMANCE IN

OUR MID ATLANTIC COASTAL AREA HAS BEEN UNSTEADY THIS FALL. AM APT

TO SIDE WITH THE 42 MEMBER NAEFS TRENDS...ESPECIALLY AFTER LAST

THURSDAYS 12Z/16 OPERATIONAL MODEL TRENDS FAILED FOR COASTAL

NJ/DEL WITH THE ALWAYS CONSERVATIVE NAEFS PREVAILING.

00Z/21 NAEFS PROB FOR >5MM ARE SOMEWHAT LESS THAN WHAT WAS

PRESENTED FROM THE 12Z/16 NAEFS FOR SUNDAY THE 19TH. IN THIS

CASE...WE`RE FURTHER REMOVED FROM THE THE PROPOSED TIME OF THE

EVENT /26TH/ AND THE PROBS ATTM FOR > 5 MM ARE ABOUT 35 PCT ALONG

THE COAST. ALSO...00Z/21 UK IS PRETTY FAR OUT TO SEA.

SO A HIGHLY UNCERTAIN FUTURE TRACK IN THE CHRISTMAS WEEKEND W

ATLC LOW. DETERMINISTIC DETAILS FOR THE CHRISTMAS WEEKEND ARE A

LOW CONFIDENCE FCST WITH TIMING, TRACK AND INTENSITY UNCERTAIN.

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I am just a forum lurker, I seriously don't know where to post anymore.

I tried to post my thoughts on this storm in the 0Z model thread, but it got buried because the 0Z Euro was coming out. My thoughts on the potential storm. Seems to be a number of schools of thought based off the 0Z thread....I guess this is just one of the many. In short, I find the strength of the eventual PV anomaly in the southern stream the key in how all this plays out, at least based on the evidence thus far.

A lot of interesting discussion and analysis here. I haven't been completely up to date on this one, but doing a quick analysis, it seems the potential for a good east coast hit seems to hinge the most on how the northern stream eventually phases with the PV Anomaly near the Gulf States. The 0Z GFS essentially treats the PV as an "ejecting" S/W trough which incites cyclogenesis ahead of the main trough which develops a strong leading edge cyclone with cold air advection turning towards the east coast as opposed to heading southward towards the GOM. The other solution favored by tonights CMC, the ECMWF, and to a degree, by the 12Z GFS, is to phase the southern PV and "absorb" it into the northern stream which then enhances the strength of CAA southward towards the GOM. This in turn develops a much deeper upper trough and eventually a much more energetic baroclinic wave up the east coast.

One thing I will say regarding the solutions is the amount of CAA all solutions develop in the low levels. It is difficult for equatorward low level cold air to suddenly shift direction and head eastward as in the 0Z GFS. It would take a sufficiently intense PV to initiate strong enough cyclogenesis to result in an eastward displacement of that low level cold air and the eventual northern cyclone the GFS develops. While the 0Z GFS certainly could be a valid solution, I find the deeper trough solutions more realistic given all model guidance have trended towards a much weaker southern stream PV Anomaly. As a result, I find a solution which results in continued CAA and a deeper developing trough more realistic then the oddball northern cyclone the GFS currently has. A weaker PV Anomaly, once phased, won't incite sufficiently strong cyclogenesis to shunt the low level CAA eastward but strong enough to enhance the continued equatorward flow of CAA, thus developing the trough deeper before ejecting the leading wave along the Gulf Stream. In terms of the GFS, the 12Z solutions seems more realistic given the circumstances. That is how I read it, at least.

Great post and I can't find a single line I don't agree with wholeheartedly.

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I am just a forum lurker, I seriously don't know where to post anymore.

I tried to post my thoughts on this storm in the 0Z model thread, but it got buried because the 0Z Euro was coming out. My thoughts on the potential storm. Seems to be a number of schools of thought based off the 0Z thread....I guess this is just one of the many. In short, I find the strength of the eventual PV anomaly in the southern stream the key in how all this plays out, at least based on the evidence thus far.

A lot of interesting discussion and analysis here. I haven't been completely up to date on this one, but doing a quick analysis, it seems the potential for a good east coast hit seems to hinge the most on how the northern stream eventually phases with the PV Anomaly near the Gulf States. The 0Z GFS essentially treats the PV as an "ejecting" S/W trough which incites cyclogenesis ahead of the main trough which develops a strong leading edge cyclone with cold air advection turning towards the east coast as opposed to heading southward towards the GOM. The other solution favored by tonights CMC, the ECMWF, and to a degree, by the 12Z GFS, is to phase the southern PV and "absorb" it into the northern stream which then enhances the strength of CAA southward towards the GOM. This in turn develops a much deeper upper trough and eventually a much more energetic baroclinic wave up the east coast.

One thing I will say regarding the solutions is the amount of CAA all solutions develop in the low levels. It is difficult for equatorward low level cold air to suddenly shift direction and head eastward as in the 0Z GFS. It would take a sufficiently intense PV to initiate strong enough cyclogenesis to result in an eastward displacement of that low level cold air and the eventual northern cyclone the GFS develops. While the 0Z GFS certainly could be a valid solution, I find the deeper trough solutions more realistic given all model guidance have trended towards a much weaker southern stream PV Anomaly. As a result, I find a solution which results in continued CAA and a deeper developing trough more realistic then the oddball northern cyclone the GFS currently has. A weaker PV Anomaly, once phased, won't incite sufficiently strong cyclogenesis to shunt the low level CAA eastward but strong enough to enhance the continued equatorward flow of CAA, thus developing the trough deeper before ejecting the leading wave along the Gulf Stream. In terms of the GFS, the 12Z solutions seems more realistic given the circumstances. That is how I read it, at least.

post in here anytime you would like. Would love to hear your analysis on upcoming events...One question, im sure you saw the 0z euro. What is causing that storm to be on the beaches of the gulf of mexico?

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Seems like Upton is now on board! :)

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHERN

CONNECTICUT...NORTHEAST NEW JERSEY AND SOUTHEAST NEW YORK.

.DAY ONE...TODAY AND TONIGHT.

HAZARDOUS WEATHER NOT EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

THERE IS THE POTENTIAL FOR A SIGNIFICANT WINTER STORM CHRISTMAS

NIGHT INTO SUNDAY NIGHT. LOW PRESSURE IS FORECAST TO TRACK FROM

THE LOWER MISSISSIPPI VALLEY CHRISTMAS EVE TO OFF THE SOUTHEAST

COAST ON CHRISTMAS DAY...THEN UP THE EASTERN SEABOARD ON SUNDAY.

SINCE THIS IS STILL SEVERAL DAYS AWAYS...THE EXACT TRACK AND

DETAILS OF THE STORM WILL LIKELY CHANGE.

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