Blizzard of 93

Yes, it’s going to be tough for York & Lancaster to get back in this one. But I think anyone along I -81 give or take a few miles & points west should still pay attention for now. I agree that the bullseye appears to be the mountains, but I would settle here for the scraps of a possible few inches of snow along I -81, just like last nights 0z GFS.

Great forecast discussion by CTP this morning. If you are near I -81 or north & west of that, you are still in the game. Here is CTP’s Discussion: .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Focus in the long term remains on the increasing likelihood of a highly elevation dependent snow event impacting the region beginning Friday night and continuing through much of Sat night as a Miller-B type surface scenario accompanies a well defined upper low that will develop across the Mid Miss valley and track east across Southern or Central PA Sat night. The 700 mb center is progged to move east along I-80 in Ohio and PA. After a mainly cloudy and rather mild Friday with temps in the upper 30s to around 40F, the boundary layer is expected to start out warm enough for primarily rain right at the onset in most areas. However, layer cooling associated with increasing uvvel, and evap cooling as the precip falls into the dry LLVl air will help to mix or change the precip over to wet snow across parts of Central and likely most or all of Ncent PA. Height falls and 1000-500 mb thicknesses falling to below 540 DAM will allow the precip to change over to snow, that will fall at a moderate to heavy rate at times late Friday night and Saturday. Of particular interest will be later Saturday morning into Sat afternoon when elevated instability being transported north toward South-central PA and areas of fairly strong 850-700 mb frontogenesis could lead to some 1-2 inch per hour, heavy snowfall rates anywhere northwest of the I-81 corridor. Critical thickness and 850 mb zero wet bulb line will exist somewhere between I-99 and I-81 during the mid to late morning hours Saturday, and this is where the greatest uncertainty is with respect to precip type and intensity. Again, we`re messaging the point that the initially warm boundary layer and periods of strong, dynamic forcing will lead to a very elevation dependent snowfall across Central and Northern PA with notably lower chances for significant snow near and to the SE of I-81. Snow accums by late Sat night could approach 8 inches at elevations over 2000 ft MSL in northern PA with 4-6 inches possible at the same elevations in Central PA. Accums in the valleys (depending on their exact elevation) will vary from 3-5 inches in the north to between 1-3 inches in most of Central PA. The threat for any sleet and/or FZRA is very minimal at this point. Increased pops for Friday night into Sat as a result of the anomalous southeasterly low level jet (over 50 kts at 850 mb) and plume of Atlantic moisture overrunning a dome of cold/stable air east of the Appalachians. This justifies categorical POPs Friday night into Saturday. The latest GEFS mean qpf ranges from 0.6 to 1 inch across the forecast area by Saturday evening.

The 0z Euro & 6z GFS put the I-81 corridor out of the game for the weekend snow. They still do like @MAG5035 & @2001kx Still 3 days for shifts to determine the final storm development & track.

The western & northern parts of our counties (Perry for me & Franklin for you) also get crushed by the 0z GFS, along with Western Cumberland County as you mentioned. It is so close to getting the rest of the LSV in the game. This run @Bubbler86 , @sauss06 , @CarlislePaWx & @canderson and l need less than a 25 mile shift to get in the 6 inch plus snow range according to the GFS. In the meantime, the bullseye appears to be @MAG5035 & @2001kx , with honorable mention to @Wmsptwx We still have 3 days to shift the bullseye around & hopefully we all get in a piece of the snow action!

I was just having a little fun ! This one will come down to the wire for us in the LSV. Hopefully it trends right to get us all in the game.

Yes, same here with the EPS for several runs showing 3 inches of snow around the Harrisburg area.

I can’t wait until we extrapolate the end of the NAM run again in a few minutes...

The 12z EPS provided a little uptick in snow amounts for the LSV. Also still some different possibilities with the placement & track of the secondary.

The 18z GFS was a nice improvement for the I-81 & Rt.15 corridors.

Great discussion this morning from CTP. There is still lots of time & many factors to sort out. We are at least in the game. “LONG TERM /FRIDAY THROUGH MONDAY/... Focus in the medium range continues to be on the increasing probability for another weekend winter storm, though there are some distinct differences with this storm compared to this past Saturday`s event. T the main feature that sticks out is the presence and favorable track of a distinct and fairly deep upper low across Central or Southern PA, this track implies a one-two punch of warm conveyor, then cold conveyor-belt precip. Ptype will be an issue across the SE third to perhaps half of our CWA, while parts of the Central Mtns and most or all of the Northern Mtns should be cold enough for all snow. Furthermore, FGEN banding and briefly heavy snow rates are possible late Friday Night/Sat morning as the mid-upper low center passes and max UVVEL intersects the descending, favorable thermal band for dendritic snow growth. Max wet bulb AOA 925 mb is about 1-2C along and to the SE of Interstate 81/I-78 corridor in Southern PA, while it`s AOB zero further north and west. Sfc temps should range from the L30s across the north, mid 30s in central PA, and Mid to Upper 30s in the SE. This vertical thermal structure and the primary nose of the warm layer aloft (and PWAT above 20mm) staying just below PA will likely result in a wet snowfall across Central PA and portions of southern PA (between and after a few to several hour change to sleet. The resulting anomalous southeasterly low level jet and plume of Atlantic moisture overrunning a dome of cold/stable air east of the Appalachians justifies increasing POPs Saturday to 90-100 percent at this day 3.5 - 4 time range. The latest GEFS mean qpf ranges from 0.6 to 1 inch across the forecast area by Saturday evening. GFS forecast soundings imply mostly snow even as far south as the greater Harrisburg area. Despite the high confidence of significant precipitation, plenty of uncertainty still remains with regard to ptypes across the area based on slightly different sfc and upper low tracks. The primary surface low is progged to weaken over the Ohio Valley Saturday, as secondary low deepens and tracks up the Mid Atlantic coast in classic Miller B fashion. Quicker development of the coastal low would imply low level winds backing from SE to NE, supplying cold air at low levels during the storm on Saturday. This would mean more wintry precip and less rain. Quicker development of the coastal low could also translate to better FGEN forcing/banding on the NW side of the developing low, which would translate to heavier precip and some dynamic cooling. It will be a couple of days before we have these answers. As always, it will be interesting to see how the hi-res guidance handles these features as the event comes in range. Based on the latest ECMWF ensemble 850temps and GEFS plumes, current forecast is for a wet snow NW half of the CWA and a wintry mix across much of the remainder of the forecast area Friday night into Saturday.”

It looks like the 6z GFS did the same thing with the late transfer, which was only good for snow in Northeast PA.

The 0z Euro was a forum divider The Harrisburg & west crew would celebrate while the east & southern tier would be upset. Still lots of time.

@MAG5035 It looks looks like the 0z GFS struggled to close off the secondary low until mostly too late to bring good snow, except to areas in Northeast PA. What are your thoughts on the run ?

The 18z EPS improved slightly over its 12z run. The mean low develops in southern VA & then tracks to the mouth of the Delaware Bay & then exits to the east.

CTP had a great forecast discussion tonight: “Regarding the potential winter storm this weekend, the ECMWF and GFS solutions are more similar as of the Jan 20/12z guidance. Both show an upper level shortwave trough moving into the Pac NW on Tuesday and digging southeastward into the Great Plains/Mid Miss Valley Region by Friday morning. Both GFS and ECMWF now showing a weak sfc low along the Gulf coast by Friday night. As the upper trough moves across the Ohio valley Friday night and Saturday, the Gulf low rides up the East coast and deepens over the Delmarva, in class Miller B fashion. GEFS and ECMWF ens also support this evolution. A mix of wintry precip should move in to the area late Friday night or early Saturday morning and last until late Saturday night. Still some unanswered questions regarding ptype. Lake effect snow showers will continue on the back side of the low through Sunday. One of the important questions to iron out in the coming days is how cold the antecedent airmass is Fri-Fri night before the storm arrives. The ECMWF soln is still more amplified, and builds higher heights ahead of the approaching upper trough on Friday, signifying warmer temps aloft. Another question is how quickly the coastal low takes over and deepens. Quicker development of the coastal low would imply low level winds backing from SE to NE, supplying cold air at low levels during the storm on Saturday. This would mean more wintry precip and less rain. Quicker development of the coastal low could also translate to better frontogenetical forcing/banding on the NW side of the developing low, which would translate to heavier precip and some dynamic cooling. It will be a couple of days before we have these answers. As always, it will be interesting to see how the hi-res guidance handles these features as the event comes in range.”

Hey, come on man, I love Philly. The city is great to visit. I also am a huge Philly sports fan as well ! Anyway, yes, the storm needs to stay on or just off the coast.

Looking over the 18z GFS, we should have a few opportunities for winter storms over the next 2 weeks. Hopefully more than 1 hits us, but there should be plenty of chances.

The ensembles show lots of possibilities with the track, which probably won’t be nailed down until Thursday night or Friday. While our benchmark is not on land, coastal huggers & just barely off of the coast tracks are ideal here back towards I-81. Otherwise, we get fringed & it’s congrats I-95. Most of our best storms, they mix or turn to rain. You are right about having No cold air to spare. This storm doesn’t look to be a rapidly deepening storm, so precip rates & exact track will make all the difference. I would be fine with a few inches of snow followed by mixing, then back to snow. A good old 3 to 6 or 4 to 8 inch snowstorm would be good. Not every storm can or needs to be a KU.

Far from out of the hunt, that track still looks good, just slightly different outcome.

The 18z GFS had a similar track to its 12z run, but the temps & thermals were slightly different, so it produced less snow this run. I would take a 2 to 6 inch snow event here in the LSV id need be, but much more is certainly on the table if everything comes together just right. We still have 5 days to go to nail down the track & determine who will be in the bullseye.

Thanks man, I’ll see what I can do ! Good to see you back! The 12z EPS mean track still goes under us. The ensemble member low locations are still ranging from inland runners, coastal huggers & ideal tracks. We are still very much in the game!

Here’s more from CTP this morning: “The overall synoptic setup with a cold high anchored to the NE and a plume of tropical moisture moving north ahead of it spells trouble in the form another possible snow/sleet event. The nose of a moderately strong LLJ (about +2 sigma at 925 mb), that`s bending cyclonically back into the region will lead to the potential for a moderate to locally heavy precip late Friday right into Sunday morning.”

CTP seemed enthusiastic this morning about the weekend potential : “A slow-moving area of low pressure will bring the potential for moderate snowfall amounts, along with some mixed precipitation, during the late Friday night into early Sunday timeframe.”

The 12z GEFS looks to be hugging the coast a bit more than the Op.

We just need a good track & I think most of us will be just cold enough in prime climo time.