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NYC/PHL Jan 25-27 Potential Bomb Part 5


earthlight

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12z EURO Snow Equivalent,

1" liquid snow line

Easton, MD starting point

East side

Easton, MD to Smyrna, DE to Cherry Hill, NJ to Trenton, to Staten Island, Crossing Manhattan, to Norwalk, CT does not go through LI

West Side

Easton, MD north to Lancaster PA, To Reading, Allentown, to East Stroudsburg, to Port Jarvis, NY to Kingston, NY to near Pittsfield, MA

post-3712-0-55856300-1295902602.jpg

Just in case anyone (like me, lol) has trouble visualizing based on place names alone

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The 18z NAM is still splitting the energy and holding part of it back accross the SE states which eventually makes it further north and brushes the coast. Big improvements though from 12z.

Take a look at the 12z NAM at hr 66. The low pressure is very elongated.

nam_850_066s.gif

Now jump ahead to hr 60 on the 18z NAM...much more of a consolidated low.

nam_850_060s.gif

The precip associated with the NAM is incredible over the SE, and if it found a way to turn the corner better we would all be looking at very high QPF. Being as were still slightly out of the NAM's good range I'm not putting too much stock in its solution atm but I like the way its currently trending. This still has the potential in my eyes to be an I-95 HECS. Sorry for such the long post but I'm five posted so I have to get all the bang for the buck I can lol.

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Upton Not Impressed

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...

-- Changed Discussion --WARM ADVECTION LIGHT PCPN SHOULD BE EXITING TUESDAY AM TO THE

NORTHEAST. POPS OVER THE NORTHERN ZONES WITH HIGHEST AMOUNTS OVER

EAST CENTRAL CT.

TEMPS ON TUESDAY ARE ABOVE FREEZING IN ALL ZONES AND COULD TOUCH 40

IN NYC. A BLEND OF MOS WAS USED.

WEDNESDAY`S STORM. LATEST SREF...GFS...GEFS AND ECMWF USED FOR THE

FORECAST. ALL MODELS TAKE LOW THAT IS FORMING OFF THE TEXAS COAST

AND TRACK IT TO NEAR THE NORTH CAROLINA COAST ON WEDNESDAY. THE

LOW THEN TRACKS NORTHEAST TO OVER THE 40N 70W BENCHMARK WEDNESDAY

NIGHT. ECMWF IS THE SLOWEST OF THE MODEL GUIDANCE IN TERMS OF

TIMING...BUT APPEARS TO FOLLOW A SIMILAR TRACK.

CONCERNS ABOUT MODEL GUIDANCE ARE HIGH DUE TO EXTENSIVE CONVECTIVE

PCPN BEING GENERATED THROUGH MODEL PARAMETRIZATION. THE LATENT HEAT

RELEASE AND THE DYNAMIC BUILDING OF THE DOWN STREAM RIDGE ARE

AFFECTED. THUS...WHILE MODEL TRACK IS CLUSTERED NICELY...HUMAN

UNCERTAINTY REMAINS HIGH FOR THE ACTUAL TRACK. THE NAM IS AN

INTERESTING EXAMPLE...AND WHILE BEING DISCARDED FOR FORECAST

INTEGRATION...IT IS RIGHT OF THE ENSEMBLED TRACK AND PRODUCES ZERO

QPF.

HAVE CONTINUED BASICALLY THE PREVIOUS FORECAST UNTIL THINGS BECOME

CLEAR. NOTE THAT NOAA WINTER RECONNAISSANCE IS BEING FLOWN FOR THIS

SYSTEM IN THE GULF OVERNIGHT. THESE CRITICAL OBSERVATIONS WILL GET

INCLUDED INTO TOMORROW`S 12Z AND SUBSEQUENT MODEL CYCLES. THUS

EXPECT THINGS TO BECOME CLEARER TOMORROW. NO WATCHES WILL BE ISSUED

THIS AFTERNOON AS WERE STILL OVER 48 HOURS FROM POSSIBLE WARNING

CRITERIA.

PTYPE IS A MAJOR ISSUE WITH THIS EVENT AS MODEL SOUNDINGS SUPPORT A

WARM NOSE ALOFT. EVEN INLAND LOCATIONS SHOULD EXPECT AT LEAST SOME

MIXED PCPN. A WINTRY MIX APPEARS TO BE THE PREDOMINATE TYPE WITH MORE

RAIN TO THE EAST. OF COURSE WITH TRACK AND QPF AMOUNT HIGHLY

UNCERTAIN...ANY SNOW AMOUNT FORECAST IS EVEN MORE UNCERTAIN. IT DOES

APPEAR THAT LIKELIHOOD OF WARNING CRITERIA SNOW IS LOW...EVEN

INLAND.

WINDS. LOW END WIND ADVISORY CRITERIA (G 40 KT) APPEARS POSSIBLE

WEDNESDAY EVENING FOR EASTERN SESSION (LONG ISLAND AND SE CT).

LASTLY FLOODING...THERE IS CURRENTLY 2 TO 3 INCHES OF WATER

EQUIVALENT WATER IT THE SNOW COVER. WITH POTENTIAL 1 TO 2 INCHES

LIQUID EQUIVALENT ADDED ON TO THIS FOR EASTERN SESSIONS (LONG ISLAND

AND SE CT)...PONDING/URBAN/BASEMENT FLOODING ARE A CONCERN. IN

ADDITION...THE WEIGHT OF THE SNOW ON FLAT ROOF STRUCTURES IS

SIGNIFICANT.

TIMING FOR PCPN ONSET IS MOST LIKELY MID TO LATE MORNING IN THE

SOUTHERN PORTION INCLUDING NYC AND LONG ISLAND ON WEDNESDAY. IT

LOOKS LIKE THE RUSH HOURS SHOULD BE DRY.

ENDING IS LATE WEDNESDAY NIGHT WITH JUST SOME LEFT OVER LIGHT SN

ON THURSDAY AM.-- End Changed Discussion --

&&

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That just shows how much spread there is with the models. Mt Holly sees warning type snows for west Jersey and Northeast Pa and Upton says low chance for warning type snows even west for their CWA.

D

I would be EXTREMELY surprised if warning criteria snows do not occur somwhere in Uptons CWA (In fact I would think 50-75% of their CWA will verify)

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The WRF-NMM and the WRF-ARW at 48hours also want to keep this 2 pieces. That usually ends up as a screw job for someone in the interior

Our main in-house Tom Clark says we will be on northern fringe of precip shield. Which means a whole lotta nuttin for folks north of 78 and especially 80...

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What's the 1" snow line again? 1 inch liquid falls as snow in that area?

Essentially Accu Pro puts out a snowfall map for the EURO its supposed to be a complete snowfall scale at 10:1 ratios, but its not (they had a similar issue with their GFS and NAM snowfall maps a couple years ago where it was only plotting the liquid equivalent) Accu pro has only had qpf for the EURO since summer I'm assuming someone forgot to put in an algorithm for the ratios. But essentially yes this would be the line where 1" liquid of snow would be plotted. The scale only goes .1 and then by the inch from there. So using standard 10:1 ratios according to the plot 10" would fall within this band. (if you believe indeed that ratios would be 10:1). I wasn't even aware of this feature til I was playing with the drop down menus last week, I have no idea how accurate this is or what goes into figuring it out with their data, I can say that the GFS and NAM snowfall plots for Accu pro are usually fairly conservative in comparison to the clown maps from Wxcaster, but this could be a case of comparing apples to oranges since I do not know anything about this feature or have used it so far this winter

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I would be EXTREMELY surprised if warning criteria snows do not occur somwhere in Uptons CWA (In fact I would think 50-75% of their CWA will verify)

I agree completely with you. I happen to think Mt. Holly's map is pretty good if you extrapolate into the Upton CWA. 15z srefs still have pretty good snow probabilties especially for the western part of the Upton CWA.

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Our main in-house Tom Clark says we will be on northern fringe of precip shield. Which means a whole lotta nuttin for folks north of 78 and especially 80...

If Tom is correct, that would make a pretty small band of heavy snow accums where the event stays all or mostly snow. Correct? I like Tom Clark but most of the Mets on NEP are pretty conservative.

D

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Our main in-house Tom Clark says we will be on northern fringe of precip shield. Which means a whole lotta nuttin for folks north of 78 and especially 80...

Tom Clark is the most conservative TV met I've ever seen. That doesn't mean he's not good. The entire station is ubber conservative with snowfall.

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I completely agree. NEP has missed many forecast totals for around my area in the Southern Poconos. Most of the time they're low.

D

The probably do a lot better for Scranton. Having family in the area, I know the snowfall climatology varies a great deal. Scranton has a seasonal snowfall of 15" and my sister said there is about 8 inches of snowcover right now at her house in the mountains west of Jim Thorpe!

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Is there a similar map put out by Upton? If so, does anyone have the url to it?

Uptons map right now is just for the small clipper coming through ending by tomorrow 1pm...no amounts above .4 inches I believe (and nothing at all below Westchester FWIW) The map for this storm isn't issued yet.

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I agree completely with you. I happen to think Mt. Holly's map is pretty good if you extrapolate into the Upton CWA. 15z srefs still have pretty good snow probabilties especially for the western part of the Upton CWA.

As a matter of fact, this is exactly what I did, and seeing that Mt Holly had 3 inches or so for Monmouth County, makes me think the met figures of 3-5 inches for our area seems fairly sound.

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Uptons map right now is just for the small clipper coming through ending by tomorrow 1pm...no amounts above .4 inches I believe (and nothing at all below Westchester FWIW) The map for this storm isn't issued yet.

where do you find the link to it when it does come out?

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Wait, NYC high temp is supposed to be close to 40f tomorrow? I can't find support for that anywhere...at least from a realistic weather standpoint given ground temps, snow cover and very cold offshore water, unless they are expecting strong low level WAA from the Gulf Stream? Nor do I see any sense whatsoever in posting a storm total map for tenths of inches from that clipper. I feel like that office has sort of fallen apart since the December debacle, especially strange considering they forecast for the second largest population in our nation.

OK, that is enough I'll stop criticizing them now.

That's also great that there will be new data for tomorrow's 12z models and SUBSEQUENT ones, what subsequent ones? It's basically a nowcast by tomorrow evening for much of the mid-Atlantic.

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NOAA Winter Recon flying over the Gulf tonight.

HAVE CONTINUED BASICALLY THE PREVIOUS FORECAST UNTIL THINGS BECOMECLEAR. NOTE THAT NOAA WINTER RECONNAISSANCE IS BEING FLOWN FOR THISSYSTEM IN THE GULF OVERNIGHT. THESE CRITICAL OBSERVATIONS WILL GETINCLUDED INTO TOMORROW`S 12Z AND SUBSEQUENT MODEL CYCLES. THUSEXPECT THINGS TO BECOME CLEARER TOMORROW. NO WATCHES WILL BE ISSUEDTHIS AFTERNOON AS WERE STILL OVER 48 HOURS FROM POSSIBLE WARNINGCRITERIA.

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

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