Central PA Thread

[pawatch]

Well just looking at these maps. This storm seems to be moving in the right direction.

First picture was put out this morning. 2nd this afternoon.

Thanks everyone for thoughts and updates on the storm.

[Eskimo Joe]

So where does LNS stand in all of this?

A coating to 2" of snow. Would not be surprised to see The Buck get 3", but that's it.

EDIT: the new snowfall map from CTP looks very reasonable.

[Master of Disaster]

Neither do I. It really bothers me when people start bashing an office just because a 4th or 5th period watch won't be issued. There are ramifications of such products with respect to local DOTs, OEMs, etc. when such products are issued so it's not something as simple as just issuing the alert.

Excellent post!!!

[Santa Clause]

NAM is UGLY. No precip for UNV and IPT...and warm for everyone.

[Jmister]

NAM is UGLY. No precip for UNV and IPT...and warm for everyone.

??? New 18z is a little warmer but precip is further NW through 18 anyway.

[Santa Clause]

Sorry, precip is NW, but it is warmer. Im bad at this just ask Jamie lol.

[EasternUSWX]

NAM is UGLY. No precip for UNV and IPT...and warm for everyone.

Just stop posting..

[JamieOber]

NAM is UGLY. No precip for UNV and IPT...and warm for everyone.

That's the best it's looked for us qpf wise

[Eskimo Joe]

Just stop posting.

Now, now...he did nothing wrong. This is a place of learning.

[EasternUSWX]

Bombing. Kinda. lol

[EasternUSWX]

Now, now...he did nothing wrong. This is a place of learning.

Every run he post wrong statements.

[NortheastPAWx]

While he's way off on precip -- he's right about temps.

EDIT: Was looking at the wrong timeframe for this storm.

[JamieOber]

I have no idea how much of that is snow up this way. Temps are real iffy. I lost my skew t plot link - anyone have a good one? Thanks.

[Santa Clause]

It IS very warm is it not???

[JamieOber]

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...

GOOD NEWS IS THAT THE MODEL SOLUTIONS ARE VERY SIMILAR WITH

TIMING...PLACEMENT AND EFFECTS. CONFIDENCE IN THE SHORT TERM FCST

HAS INCREASED MARKEDLY IN THE LAST 12-18 HRS.

SHARP POS-TILTED TROUGH OVER THE CENTRAL STATES WILL SWING VERY

QUICKLY TO A MERIDIONAL OR EVEN SLIGHT NEG TILT BY WED EVENING. A

SFC LOW WILL DEVELOP IN THE CAROLINAS AS THE HEIGHT FALLS OCCUR

TONIGHT AND VERY EARLY WED. THE DEEP MOISTURE FLOW FROM THE GULF

GETS CUT OFF FAIRLY QUICKLY...BUT THE ATLANTIC WILL KEEP THE

PRESSURES DROPPING. LACK OF DEEP/ANOMALOUS EASTERLY FLOW IS A

NEGATIVE FOR THIS STORM...BUT THE DYNAMICS ARE VERY POWERFUL.

SW-NE UPPER JET IS WELL OVER 100KTS. THE FAST NORTHEASTWARD

MOVEMENT OF THE STORM WILL LIMIT THE TIME PERIOD OF HEAVIEST

PRECIP. HOWEVER...THE DYNAMICS PULL MUCHO MOISTURE IN AND TEMPS

COOL VERY RAPIDLY FROM TOP DOWN. THEREFORE...A CHANGE FROM RAIN TO

SNOW WILL OCCUR FROM TOP DOWN. SFC TEMPS ARE STILL RATHER WARM FOR

ACCUMS TO OCCUR IN THE LOWER ELEVS - ESP THE LOWER SUSQ - UNTIL

LATE IN THE DAY...THOUGH. NAM/GFS BUFKIT PROFILES ARE EXTREMELY

WET IN THE SERN HALF OF THE AREA...WITH VERY STRONG UPWARD OMEGAS

IN THE MID LEVELS...RIGHT IN BEST THE DENDRITIC SNOW GROWTH ZONE.

THE STORM SHOULD END RATHER QUICKLY FROM W-SE WED NIGHT. QPF IN

THE COLD AIR AND HPC MANUAL PROGS GIVES HIGH PROB OF A 2-5 INCH

SNOWFALL FOR THE SOUTHERN HALF OF THE STATE...AND 6+ ARE POSSIBLE

IN THE HIGHER ELVATIONS OF THE LAURELS WHERE TEMPS ARE COLDER

FIRST AND OVER THE POCONOS/SCHUYLKILL CO WHERE THE SNOW LEVELS

DROP FIRST IN THE EAST AND THE PRECIP WILL LAST INTO THE MIDDLE OF

THE NIGHT. WILL POST A WINTER STORM WATCH FOR SOMERSET AND

SCHUYLKILL COS. AGAIN...THE DRAWBACKS FOR HEAVIER SNOW IN THE

MORE-POPULOUS AREAS OF THE MID AND LOWER SUSQ VALLEY WILL BE THE

LATER TURNOVER TO SNOW AND THE WARM SFC TEMPS. SNOW MAY FALL FOR A

WHILE BUT MELT AS IT FALLS WED AFTN. THIS MAY SOUND FAMILIAR. THE

S-L RATIOS LOOK LIKE A NEAR 10:1 WITH A HEAVY WETNESS TO IT AS THE

SNOW GRABS LOTS OF SUPER- COOLED WATER ON THE WAY DOWN FROM ON

HIGH.

[sauss06]

Is that from october 28th jamie? lol looks like a similar read no?

[EasternUSWX]

I hope Joe Bastardi was joking when he made this.

[Jmister]

I have no idea how much of that is snow up this way. Temps are real iffy. I lost my skew t plot link - anyone have a good one? Thanks.

TwisterData is pretty good. Shows a marginal profile in State College by hour 27. If the snow is hard enough, not much melting should take place by the time it hits the surface.

http://www.twisterdata.com/index.php?sounding.lat=40.6973&sounding.lon=-78.0579&sndclick=y&prog=forecast&model=NAM&grid=221&model_yyyy=2011&model_mm=12&model_dd=06&model_init_hh=18&fhour=27&parameter=TMPF&level=2&unit=M_ABOVE_GROUND&maximize=n&mode=singlemap&sounding=y&output=image&view=large&archive=false

[JamieOber]

Is that from october 28th jamie? lol looks like a similar read no?

I know! It really does.

TwisterData is pretty good. Shows a marginal profile in State College by hour 27. If the snow is hard enough, not much melting should take place by the time it hits the surface.

http://www.twisterda...e&archive=false

Thanks!

Yeah, that's as marginal as it gets. hour 30 is good but boy, 27 is close.

[JamieOber]

It IS very warm is it not???

You and I are in the same boat - it's very close hour 27 but it's getting colder.

[EasternUSWX]

We know things can change a few degree colder and we win. Lets see what tonights 0Z have to say. Maybe we will get that last minute east push of cold air.

[EasternUSWX]

RUC is pretty cold compared to the other models.

[wxmeddler]

After conferring with some others in the wxcenter, I think there is really only 2 things that could happen.

1st is a GFS-esk solution that is mainly rain for the duration of the storm then a quick burst of snow at then end with a coating to 2" for Lancaster, York and Piedmont region. Higher amounts for points west in the blue ridge into the great valley like 2-4". Higher elevations will obviously get more.

2nd is one that I thought of as a possibility in the back of my mind and finally came to light with the 18z NAM. Its the fact that the surface low actually bombs quickly just off the coast. Wrapping the cold air quickly around and giving higher amounts for all those involved but following the same contours of what I outlined earlier. This solution would also bring a quick inch for the I-95 Corridor.

[EasternUSWX]

After conferring with some others in the wxcenter, I think there is really only 2 things that could happen.

1st is a GFS-esk solution that is mainly rain for the duration of the storm then a quick burst of snow at then end with a coating to 2" for Lancaster, York and Piedmont region. Higher amounts for points west in the blue ridge into the great valley like 2-4". Higher elevations will obviously get more.

2nd is one that I thought of as a possibility in the back of my mind and finally came to light with the 18z NAM. Its the fact that the surface low actually bombs quickly just off the coast. Wrapping the cold air quickly around and giving higher amounts for all those involved but following the same contours of what I outlined earlier. This solution would also bring a quick inch for the I-95 Corridor.

Do you think the models could be under doing the cold air out west? I think if the NAM was right the temps would be a bit colder cause it really goes nuts off the coast.

[wxmeddler]

Do you think the models could be under doing the cold air out west? I think if the NAM was right the temps would be a bit colder cause it really goes nuts off the coast.

Zak, Could be.. if your worried about that then I would wait for the 0z soundings to come out. Overall though I think the models have a good hold on the air temperature above the boundary layer in the Ohio valley. Where the cooling matters is within 100 mb of the surface is going to be controlled by dynamic cooling and precipitation rates. This is going to determine snow ratio's and how much melts before accumulating.

Edit: Also, its important to consider not when the storm will "bomb" but where the storm will bomb. The earlier it is.. the earlier we can get snow on the ground.

[EasternUSWX]

4-6hrs of snow at .5-1" per hr = 2-6" - 1" of melting so 1-5" across the region.

[MAG5035]

Been away from the computer this afternoon, really itching to post haha.

Anyways, I think folks worrying about rain cutting markedly into snow amounts especially in the lower Susquehanna valley are legitimate in their concerns. This storm, as has been noted by alot of folks including myself has some parallels to our October storm. However there is one major difference that is probably going to have ramifications for our southeastern folks. When we had the October snowstorm, what really made the storm work was the fact we had the kicker system a couple days prior that established an unseasonably cold airmass and pretty much preset everything almost ideally to make for what seemed like a typical December/Jan snowstorm in its ease (considering time of year) of delivering sig snow to folks in the Sus Valley and of course up into New England. This one will not have that, as we will have to see how well the frontal boundary presses as the wave rides up. Getting the cold efficiently past the Apps into the southeastern zones can be a slow process, thus rain might not turn to snow until the dynamics of this storm kick in when it deepens. If this setup presented itself for the late October system, alot of areas that had half decent snow probably would've gotten all rain. Fortunately, it's December..so we should be talking accululating snow at some point in the game for everyone that gets the QPF..the question is how long does it take to turn over.

So I see it as a couple options, if the storm ends up backing east and focuses a snow axis from say MDT to ABE and points north/northeast of there.. than yea this is probably going to be more of a widespread 3-4 incher at best with higher spots cracking 6" or so and Pocono's high ground perhaps doing much better than that. The placement might be OK but the issue of getting the cold there in time will remain. If this storm continues the way of what the 18z NAM just threw out, than the heavy snow axis could be the JST/AOO/UNV/IPT corridor or most likely just southeast of that line. If heavy QPF gets focused on these areas, they won't have as much trouble turning over, especially JST and the laurels..where the cold air will get there first and then should bleed relatively easily into the western ridge and valley locations. If the .75-1.00 inch line can indeed work that far back, we could be talking a 6-10 inch event for the axis of heaviest with highest Laurels doing better than that.

[hckyplayer8]

We can get snow during a +NAO especially when it's on the move.

Good example is 2002-2003:

Prior to the Xmas Day storm it surged positive and it was positive leading up to the PDII storm. It was also positive right before the 12/5 storm that year. Of course, it's forecasted to drop but hasn't yet so this is a bit diff.

I never said we can't get snow. But I'm starting to see more and more posts mummering about the warming of the lower and mid levels. Especially for those in the valleys. Fact is there is no block and I think we are pretty lucky this isn't cutting more to our West than currently modeled.

[JamieOber]

I never said we can't get snow. But I'm starting to see more and more posts mummering about the warming of the lower and mid levels. Especially for those in the valleys. Fact is there is no block and I think we are pretty lucky this isn't cutting more to our West than currently modeled.

Yep....I was worried about that all along.

[EasternUSWX]

Not bad. Please just get a bit colder at 0Z and it is on!