Central PA Late Spring 2012

[Jim Marusak]

The Jets Phase...Your a Met, you should know this! =P

ON SUN...NRN STREAM SHORTWAVE DIGS SE ACROSS THE OH AND TN

VLYS...WHILE THE SRN STREAM WAVES LIFTS NE ACROSS NRN FL AND OFF

THE SE COAST. THESE TWO WAVES WILL THEN PHASE SUN NIGHT/MON

AM...THEREBY ACCELERATING THE CYCLOGENESIS ALONG THE MID ATLC

COAST. THE MODELS CONTINUE TO DEPICT AN INLAND...NORTHWARD TRACK

OF THE DEEPENING LOW...WITH THE H7-H5 TRACK FROM THE INTERIOR MID

ATLC REGION (CEN/NRN VA) NORTHWARD THROUGH CEN PA/NY. GIVEN THE

INTENSIFICATION/AMPLIFICATION OF THE SYSTEM AND EVENTUAL NEGATIVE

TILT WITH THE UPPER TROUGH SUN NIGHT AND MON...MODELS CONTINUE TO

SHOW STRENGTHENING COUPLED JET DYNAMICS WITH INCREASING MID LEVEL

DEFORMATION/QVECTOR CONVERGENCE AND ASSCD

FRONTOGENETICALLY-ENHANCED PCPN DEVELOPING ACROSS THE CEN WV NORTH

THROUGH WRN PA/WRN NY. COLD AIR AVAILABILITY WITH THIS SYSTEM IS

MARGINAL AT BEST FOR WIDESPREAD...HEAVY SNOWFALL (LARGELY DUE TO

THE TIME OF YEAR)...AS 850 MB TEMPS ARE PROJECTED TO BOTTOM OUT IN

THE -3 TO -6C RANGE (OR CLOSE TO 2 STD DEVS BELOW NORMAL).

MEANWHILE...MODELS BRING WET BULB ZERO HEIGHTS OF 2000 FT MSL OR

LOWER ACROSS WRN NY/PA...ERN OH...WV...AND ACROSS WRN MD/VA

THROUGH THE DAY ON MON. NOT SURPRISING WITH THE FRONTOGENETIC

POTENTIAL WITH THIS SYSTEM...THE MODELS (BOTH NAM/GFS) CONTINUE TO

SHOW NEGATIVE EPV'S WITHIN THE 800-600 MB LAYER AND THUS THE

POTENTIAL FOR EMBEDDED ELEVATED CONVECTION OVER WRN

PA...SUPPORTING THE POTENTIAL FOR HEAVY...CONVECTIVELY-ENHANCED

SNOWFALL RATES OVER THAT REGION.

i know it, i just don't believe the track. i just don't think the low-center will retrograde longitudinally like the models have while moving poleward. if anything it may stay closer to the 00Z gfs or canadian regional track. so if anything shift the surface-low track east. it still dumps a lot of snow in western PA and western upstate NY (8-10"). but the surface reflection of the NAM is just not something I buy.

[MAG5035]

guys and gals. question here, maybe this has been covered in previous posts but call me late in the game here. when's the last time we had a storm come up the coast and actually steer its way into the poconos and up into upstate NY and southern/central ontario with this type of situation? because i know the models are still trending for that when looking at the latest run, but i don't remember the storm track usually going that way with this type of system. usually if anything it would make a bee-line for i-87 or i-91 and make its way towards montreal or quebec city, not head back to kingston ON or even Toronto; at least as i remember things over the years.

Last major event that comes to mind is the March 3-4th, 1999 event that developed a major low that moved up thru eastern pa up into upstate New York, making for a rain/thunderstorms rapidly turning into a several hour period of blizzard conditions and thundersnow with the big amounts in the Laurel's thru western New York. Actually this was a pretty memorable western NY event. Track is somewhat similar, a bit further inland and less of an arc inward. This kind of a track/evolution doesn't happen very often, thats for sure. Usually shenanigans like this only exist on the hour 264+ GFS... not staring us in the face in the short term.

This is going to be quite a spectacle, I haven't seen amounts that high on CTP's snowmaps since they started using the plan view for the 10-11 winter.

[PottercountyWXobserver]

MAG, let us know how the Euro looks will ya. Would love to know if it is still showing 12-16" for some

[MAG5035]

MAG, let us know how the Euro looks will ya. Would love to know if it is still showing 12-16" for some

Yea your def still good to go on the 0z Euro Potter looking at the text from BFD.

MON 00Z 23-APR 3.3 -2.4 1010 81 75 0.02 549 541

MON 06Z 23-APR 1.3 -2.1 1003 99 96 0.16 545 542

MON 12Z 23-APR 0.6 -4.5 997 95 98 0.39 539 542

MON 18Z 23-APR 0.0 -5.5 993 86 100 0.42 532 538

TUE 00Z 24-APR -0.4 -5.3 994 93 99 0.33 528 533

TUE 06Z 24-APR -0.8 -5.4 993 93 98 0.14 526 532

[MAG5035]

AOO and UNV have over an inch of QPF that is probably mainly snow and a prior 6 hour frame of a few tenths that might be debatable. JST has like 1.6" or so QPF, so pretty much RIP Johnstown this run. Pit is more like the .6-.7 QPF range, so it seems like the Euro might be focusing the ground zero axis a bit more over central PA this go around.

[toronto blizzard]

Any idea what the EURO showed for YYZ Toronto? Does it look good for snow

[Jim Marusak]

take a look at the surface track on that reanalysis MAG, and look at the current canadian regional. they look awfully similar, with the actual system a bit further east than the current GEM regional track. the NAM and GFS aren't so much as in tune with that as they just hook too far back. maybe i'm wrong with this, but the combination of my gut and the model suite i am seeing just doesn't add up as hyped attm.

[MAG5035]

Any idea what the EURO showed for YYZ Toronto? Does it look good for snow

Bout a half inch of QPF that is probably snow, 2m temps are a bit meh though.. bout 36-37.

[MAG5035]

take a look at the surface track on that reanalysis MAG, and look at the current canadian regional. they look awfully similar, with the actual system a bit further east than the current GEM regional track. the NAM and GFS aren't so much as in tune with that as they just hook too far back. maybe i'm wrong with this, but the combination of my gut and the model suite i am seeing just doesn't add up as hyped attm.

Yea i do agree that the GFS and NAM might be retrograding and cutting this thing off a bit much.. however i'm not sure that it would even matter as the damage is going to get done as the low rapidly develops with the negatively tilted trough and moves up through. A more typical scenario would be a bit less of a negative tilt which would send the low the rest of the way up the coast or fade it toward the benchmark... making for still a snow event but probably not something as crazy as what we have forecast right now. The fact that the low will come straight up or perhaps bend inward a bit is going to hang and focus the deform/CSI banding for a more extended time over western and/or central PA. Throw in a near classic 500mb western ridge alignment for C-PA as well. Looking at the ewall Euro, it seems like that might be more progressive taking it up and out instead of stalling/occluding out.. and it still delivered a major blow, just a bit further east than the NAM axis.

[cfbaggett]

State College is now under a Winter Storm Watch. Personally, I think the Euro/UKMet solution will verify with the surface track. They match the 1928 analog better.

Winter Storm Watch

URGENT - WINTER WEATHER MESSAGE

NATIONAL WEATHER SERVICE STATE COLLEGE PA

337 AM EDT SUN APR 22 2012

...A DESTRUCTIVE LATE SEASON SNOWSTORM IS POSSIBLE SUNDAY NIGHT

THROUGH TUESDAY MORNING...

.SURFACE LOW PRESSURE WILL FORM ALONG THE SOUTH CAROLINA COAST

EARLY THIS MORNING AND MOVE NORTH ALONG THE EASTERN SEABOARD

REACHING THE DELMARVA PENINSULA TONIGHT. A DEEPENING...AND SLOW

MOVING UPPER LOW WILL MOVE NORTHEAST FROM THE OHIO RIVER VALLEY

THIS AFTERNOON AND CROSS CENTRAL OR EASTERN PENNSYLVANIA MONDAY.

THERE IS INCREASING CONFIDENCE FOR A VERY HEAVY AND WET LATE

SEASON SNOWFALL ACROSS THE NORTHERN AND WESTERN MOUNTAINS OF

PENNSYLVANIA...AND PARTS OF THE CENTRAL MOUNTAIN REGION AS WELL.

GIVEN NEARLY FULL LEAF OUT ACROSS THE REGION...HEAVY WET SNOW

ACCUMULATIONS WILL PRODUCE WIDESPREAD TREE DAMAGE AND POWER

OUTAGES FROM FALLING TREES AND LIMBS COMBINED WITH LOCALLY STRONG

NORTHERLY WINDS FROM THIS STORM. PERSONS IN THE WATCH AREA SHOULD

PREPARE FOR EXTENDED POWER OUTAGES AS A RESULT OF THIS STORM.

PAZ012-018-019-025-026-034-035-041-045-222000-

/O.EXB.KCTP.WS.A.0002.120423T0400Z-120424T1600Z/

NORTHERN CLINTON-NORTHERN CENTRE-SOUTHERN CENTRE-BLAIR-HUNTINGDON-

BEDFORD-FULTON-NORTHERN LYCOMING-SOUTHERN CLINTON-

INCLUDING THE CITIES OF...RENOVO...PHILIPSBURG...STATE COLLEGE...

ALTOONA...HUNTINGDON...MOUNT UNION...BEDFORD...MCCONNELLSBURG...

LOCK HAVEN

337 AM EDT SUN APR 22 2012

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

MORNING...

THE NATIONAL WEATHER SERVICE IN STATE COLLEGE HAS ISSUED A WINTER

STORM WATCH...WHICH IS IN EFFECT FROM LATE TONIGHT THROUGH

TUESDAY MORNING.

* LOCATIONS...PORTIONS OF THE CENTRAL AND SOUTH CENTRAL MOUNTAINS

* HAZARD TYPES...HEAVY SNOW...ACCOMPANIED BY INCREASING

NORTHERLY WINDS LATE SUNDAY NIGHT AND MONDAY.

* ACCUMULATIONS...4 TO 8 INCHES

* TIMING...SUNDAY NIGHT THROUGH TUESDAY MORNING.

* IMPACTS...EXTREMELY HAZARDOUS TRAVEL FROM PERIODS OF HEAVY SNOW

AND POOR VISIBILITY. THERE IS THE POTENTIAL FOR WIDESPREAD TREE

DAMAGE DUE TO HEAVY WET SNOW ACCUMULATIONS...LEADING TO DOWNED

UTILITY LINES AND POTENTIALLY LENGTHY POWER OUTAGES BEGINNING LATER

SUNDAY NIGHT.

* WINDS...NORTH TO NORTHEAST 10 TO 20 MPH WITH GUSTS UP TO 25

MPH SUNDAY NIGHT...INCREASING TO 15 TO 25 MPH WITH GUSTS TO 40

MPH MONDAY.

* TEMPERATURES...30 TO 35 DEGREES.

* VISIBILITIES...BELOW ONE HALF OF A MILE AT TIMES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR SIGNIFICANT

SNOW...SLEET...OR ICE ACCUMULATIONS THAT MAY IMPACT TRAVEL. STAY

TUNED TO NOAA WEATHER RADIO OR YOUR FAVORITE SOURCE OF WEATHER

INFORMATION FOR THE LATEST UPDATES. ADDITIONAL DETAILS CAN ALSO

BE FOUND AT...WEATHER.GOV/STATECOLLEGE.

&&

$$

[EasternUSWX]

Ok seriously f college tomorrow I am chaing this sh**

[EasternUSWX]

BANDS OF STRONG FRONTOGENESIS/CSI ROTATING NWWD ACROSS

ACROSS THE CWA COULD BRING SOME THUNDER SNOW AFTER MIDNIGHT

SUNDAY NIGHT...THROUGH THE DAY MONDAY. SNOWFALL RATES ACROSS THE

NW MTNS AND LAUREL HIGHLANDS COULD EASILY BE 1-2 INCHES/HOUR AT

TIMES.

Ya going to my grandmas in Johnstown!

[canderson]

Have fun chasing, should be a blast.

Rain's held off all morning so I can do my tilling work, if it can hold off until 2 or 3 (other than drizzle) I'll be happy.

[Voyager]

BANDS OF STRONG FRONTOGENESIS/CSI ROTATING NWWD ACROSS

ACROSS THE CWA COULD BRING SOME THUNDER SNOW AFTER MIDNIGHT

SUNDAY NIGHT...THROUGH THE DAY MONDAY. SNOWFALL RATES ACROSS THE

NW MTNS AND LAUREL HIGHLANDS COULD EASILY BE 1-2 INCHES/HOUR AT

TIMES.

Crazy enough for January/February, but downright impressive for late April! As a side note, but relevent anyway, as we get closer to the event the NWS forecasts are indicating more of a chance of some snow even in my area.

[MAG5035]

So dual pol radar is going to get it's first big useage around here with a snowstorm after all. Should be interesting to monitor the banded snows with it.

[JamieOber]

So dual pol radar is going to get it's first big useage around here with a snowstorm after all. Should be interesting to monitor the banded snows with it.

When's your first guess map?

The call for State College/Altoona is going to tough tough tough. I see a lot of people have latched onto Accuweather's 1.3 inches for State College on social media.

[Jmister]

I suspect we will see our usual last minute trend weaker and further east than where the 72-36 hr range modeling had the storm. It seems to be a rule of thumb with nor'easters...

[Paweatherguy1]

I suspect we will see our usual last minute trend weaker and further east than where the 72-36 hr range modeling had the storm. It seems to be a rule of thumb with nor'easters...

Yep, I am seeing that...and it is going to end up causing my area to bust.

[EasternUSWX]

NAM shifts east with Derform. Snow gets even to my house. Maybe I won't have to go anywhere? Lol

[JamieOber]

I suspect we will see our usual last minute trend weaker and further east than where the 72-36 hr range modeling had the storm. It seems to be a rule of thumb with nor'easters...

bit further east but bit stronger than 06 and about same as 0Z? Is that correct?

[JamieOber]

Weird, near stall and slowly moving northwest right across PA on NAM,

[OSUmetstud]

I suspect we will see our usual last minute trend weaker and further east than where the 72-36 hr range modeling had the storm. It seems to be a rule of thumb with nor'easters...

I think, if anything, nor'easters trend NW in the 72 hr time frame. Many times the convection in the gulf is underestimated or poorly parameterized which strengthens the downstream ridging and causes the storm to trend a bit farther NW. It doesn't always work, obviously.

[MAG5035]

Henry M doesn't seem too thrilled with people throwing around the "historic" term

Sunday Disco

Going with a Category 3 winter storm despite it being April. Chart below.

I have to give credit to the European model because it FINALLY did a good job catching on to the storm last weekend. Given the track record of the model this winter, I think most Mets dismissed the storm potential early last week, but it was not like we didn't talk about the possibility. Personally, I really don't want to deal with a late-season snowstorm. The weather has been just too nice to deal with snow.

The best part of the storm will be the drought-denting rain coming. Many places will have over a 1/2 inch of rain and perhaps even 2-3 inches of rain with thunderstorms mixed as the storm intensifies.

As I have said the past couple of days, taking a cautious approach to a spring snowstorm is the best way. For the general public, you can tell them a week ago a snowstorm was coming, but most would have enjoyed the nice weather. Today is the day where people will begin to react, so I think the approach that the NWS here in State College and AccuWeather.com meteorologists have taken has been the right approach and the warnings that are going out now are the appropriate warnings.

The map below shows the snow totals for the storm. This is from the AccuWeather.com Forecast Operations team and clearly shows the high ground of western Pennsylvania getting hit with a heavy wet snowstorm.

So lets go through some of the snow issues.

1. Time of day - The snow is coming during the day on Monday. It has to snow at a rate of a 1/2 inch or better per hour to accumulate, otherwise the April sun will melt the snow on the ground just as quick as it falls.

2. Snow Ratios - looks like between 1:6 and 1:10 ratios depending on location. For an inch of liquid you get 6-10 inches of snow depending where you live.

3. Snow Intensity - snow rates could reach an inch or more per hour with thunder mixed in. It happens during spring storms.

4. Duration - About 8 hours in any one location with 2-4 hours of intense snow.

5. WINDS - Winds behind the storm will be gusting at 25-35 mph and will shake some of the broken branches off the trees.

Lastly, this is not a historical storm. It snows in April, especially over the higher elevations of Pennsylvania and western New York. Lets keep things in perspective.

Yea.. it does snow in April, and late April it happens here and there. That's usually a couple inches of slop in the high ground or some lake effect snow showers.... we're talking up a foot+ possible in the Laurels and 4-8 in the adjacent central counties. A snow event around this late occured in 1986 apparently and this storms best analog is one that happened in 1928. It's not like a storm of this magnitude happens in mid-late April every year.. or decade for that matter. If we get as advertised.. i'd call it historic. Additionally, the national weather service has issued some pretty heavily worded watch statements.. specifically the newest added section for the AOO-UNV corridor. These lower elevations have areas where trees have leafed out very early.. so if we actually manage 4-8 inches into places like Altoona or State College it's going to make a mess as it will be of the concrete variety. Hence CTPs statement wording including "destructive late season winter storm" and "persons in the watch area should prepare for extended power outages as a result of this storm".

[Santa Clause]

A bit east...interesting??

[Jmister]

Comparison of 00z, 06z, and 12z NAM at 12z Monday....

[Paweatherguy1]

Henry M doesn't seem too thrilled with people throwing around the "historic" term

Yea.. it does snow in April, and late April it happens here and there. That's usually a couple inches of slop in the high ground or some lake effect snow showers.... we're talking up a foot+ possible in the Laurels and 4-8 in the adjacent central counties. A snow event around this late occured in 1986 apparently and this storms best analog is one that happened in 1928. It's not like a storm of this magnitude happens in mid-late every year.. or decade for that matter. If we get as advertised.. i'd call it historic. Additionally, the national weather service has issued some pretty heavily worded watch statements.. specifically the newest added section for the AOO-UNV corridor. These lower elevations have areas where trees have leafed out very early.. so if we actually manage 4-8 inches into places like Altoona or State College it's going to make a mess as it will be of the concrete variety. Hence CTPs statement wording including "destructive late season winter storm" and "persons in the watch area should prepare for extended power outages as a result of this storm".

So let's see...Henry M hypes up every 6 inch storm in January...but when there is a storm that could produce a foot of snow in places on april 22nd, that isn't historical.

He is a joke.

[EasternUSWX]

Henry M doesn't seem too thrilled with people throwing around the "historic" term

Yea.. it does snow in April, and late April it happens here and there. That's usually a couple inches of slop in the high ground or some lake effect snow showers.... we're talking up a foot+ possible in the Laurels and 4-8 in the adjacent central counties. A snow event around this late occured in 1986 apparently and this storms best analog is one that happened in 1928. It's not like a storm of this magnitude happens in mid-late April every year.. or decade for that matter. If we get as advertised.. i'd call it historic. Additionally, the national weather service has issued some pretty heavily worded watch statements.. specifically the newest added section for the AOO-UNV corridor. These lower elevations have areas where trees have leafed out very early.. so if we actually manage 4-8 inches into places like Altoona or State College it's going to make a mess as it will be of the concrete variety. Hence CTPs statement wording including "destructive late season winter storm" and "persons in the watch area should prepare for extended power outages as a result of this storm".

That guy is a complete joke. Ya 15-20" in April not historic at all.

[PennMan]

When's your first guess map?

The call for State College/Altoona is going to tough tough tough. I see a lot of people have latched onto Accuweather's 1.3 inches for State College on social media.

It will be very interesting to see if the Nittany Valley's elevation will play a role like it has in the past...being at 900-1400ft has definitely been an advantage over some of the other valleys in situations like this, such as 10/15/09.

Even a few inches of slop could cause serious tree damage...lots of trees with basically full leaf-out already in the valley.

[Paweatherguy1]

That guy is a complete joke. Ya 15-20" in April not historic at all.

I like the comment that duration will only be 8 hours? What in the heck is he looking at. WPA duration of the snow will probably be about 16 hours or so.

He is horrible.

[MAG5035]

When's your first guess map?

The call for State College/Altoona is going to tough tough tough. I see a lot of people have latched onto Accuweather's 1.3 inches for State College on social media.

I've been pretty busy but I'll try to maybe scribble something up at some point, might be this evening though. This def is going to be a tough one for our lil area though, probably a wide range of accumulations. Right now I think AOO and UNV probably get the lower end of that 4-8 range (3-6ish), with AOO possibly being the one that sees more.