5/16 Chase Update

As I was expecting, there are plenty of clouds over the Middle Atlantic States. We'll really need some break of sunshine in order to boost the CAPE values and have some decent storms by PA standards. 0z cloud product guidance has the WRF most aggressive with the clouds (which is typically when compared to the GFS, largely because of the grid spacing) with low clouds early today and then mid-clouds the remainder of the day. The GFS would offer more sunshine through mid-afternoon, but considering it doesn't have any clouds this morning (and we are currently cloudy), not sure how much to buy it.

6z WRF looks disorganized with the precipitation early in the day before it becomes more well-defined around the cold front this afternoon. The 0z Penn State 4km WRF simulated reflectivity shows some prefrontal convection forming along the ridges west of State College around 18z. Those cells move east of State College by 21z and the front becomes the focus for convection, with frontal convection reaching State College around 0z and departing the area likely by 3z. While I would like to throw all my chips into this model, I know that would just be the illusion of predictability (as Rich Grumm, NWS CTP says).

As I stated in last night's post, chasing will ultimately be determined by what the current observations are later this afternoon. SPC still has a good chunk of PA in the slight risk, with 5% tornado probability, 15% hail (south of State College) and 15% damaging winds.

Work, then chase?

Briefly, I have tentatively plans to chase tomorrow afternoon. Tentative enough that I got my gear out and charging. :)

While I'm not anticipating anything widespread, a slight risk is enough to get me moving out of town. However, I work until about 4:30, so that will keep me anchored until then. Ultimately, it will come down to what the current weather situation is when I leave the office. I think the front will be close to the State College area between 21-00z, which would give me plenty of time to get into position south of town in the valley. While dewpoints will be in the low 60s, if we can get some sunshine in the afternoon, that will help boost CAPE values to around 1000 J/kg. With the front swinging through, that will provide the lift so the storms can tap into the energy, but hopefully not too soon.

We'll see what happens soon.

Bear Meadows hike; Wed. severe weather and Thurs. lack thereof

Enjoyed a pleasant Wednesday late afternoon/early evening out in Rothrock State Forest. I hiked the Bear Meadows Loop, which is 3.5 miles in about 2 hours. It wasn't a difficult or steep hike (200' change over the whole trail), but being that Bear Meadows Natural Area is a boreal bog, there were places that were, well, muddy and soupy. Some navigating was required off the trail. :) Anyway, it was a great afternoon to be outside. When I started the hike around 4:30, it was sunny and near 70. The sun went under clouds arriving from the west shortly after I started and it had become a bit cool by the time I got back to my car. I then decided to try to find the fire lookout tower, which I kinda knew was closed (because of vandalism). I got up there after traversing various gravel roads and found a couple setting up camp. There really wasn't a good lookout point so I just walked around for a bit before leaving.

There was some severe weather across parts of the middle Mississippi Valley, although it would have been and was farther west than I would have wanted to go. Today, there have been several short periods of rain, otherwise clouds with some breaks of sunshine. Looks like another band will move through here soon with the front.

I was just looking at the models and found that this front going through the interior East today will slowly move to the East Coast and then stall. As this happens, both the GFS and CMC (Canadian model) show a low becoming cutoff along the tail-end of the front somewhere over the northern Caribbean/near Florida early next week. On occasion, you can get a tropical disturbance to form, but its too early to tell if that will occur.

Saturday, Tomorrow, Thursday

The severe weather on Saturday remained confined to New York and the New England States. A few non-severe thunderstorms moved across northeast and north central Pennsylvania in the afternoon, mainly north of I80 and west of the Alleghenies. A few showers formed to the southeast of State College as the front approached, but State College stayed dry.

Looking ahead, tomorrow (Wednesday, 5/13) looks to be a volatile day across parts of the middle Mississippi River Valley. While a tornado threat is probably in the afternoon, models, forecasts and SPC is eyeing a potential damaging wind event overnight. While I had considered going out to Illinois tomorrow (about a 10 hour drive) given that I have 3 days off, I just don't think the payoff will be worth it. Plus, it will be quite a pleasant day in Happy Valley and I hope to go to Rockrock State Forest.

Locally, I may head out Thursday afternoon as the cold front slides through the region. Severe weather is very much unlikely and even thunderstorms are in question as cloud cover will limit surface heating. So, this will be a last minute call.

5/9/09: Severe Thunderstorm Watch for upstate New York

A severe thunderstorms watch has been issued for all of upstate New York this afternoon. Bowing line segments exist currently over Lake Ontario. Patchy sunshine over northeastern Pennsylvania has yielded CAPE values around 500J/kg. That, coupled with the eastward moving cold front, new convection has formed in the last half hour from Buffalo, NY to Erie, PA along the lakeshore. While yesterday's 15z SREF kept things mainly dry over Pennsylvania (SREF average total precip total less than 0.10"), we'll see if anything can hold together as it crosses the Appalachians. It will be tough as we are under quite a bit of cloud cover, which is limiting our temperatures a bit (currently at 73 with a dewpoint of 62).

I'm tethered to a desk today, so I'll be staying put.

Elevated convection, then warmer

The disturbance, a mesoscale convective vortex yesterday, is currently sputtering across central PA. There is some elevated convection west of the Alleghenies mountains and is heading towards Happy Valley/State College. Question is will it be able to penetrate the State College Bubble Effect? What I do know is this thunderstorm/convection action is ahead of a warm front and it will be getting nice and toasty this weekend. While yesterday we only got into the mid-50s in State College and was our transition day to the warmer weather pattern, today should be in the low to mid-70s. Tomorrow will be even better, especially for the spring scrimmage (Blue-White Game) here at Penn State with highs (I think) in the mid-80s. Talking to one of our interns who is a senior here, he said this is likely one of the warmer game days he's going to be at. The rest of the weekend and the start of next week will keep the summer-like weather around.

Lightning strikes this morning in PA as of 9:41AM LDT.

What a marvelous Friday. I've been on a weird work schedule, so had a rare Friday off today. Temperatures beat my expectations, likely due to the fact that the clouds broke around noon. State College made it well into the 60s.

While I ran some errands in the morning, I came back home and worked on learning a new weather program. Unfortunately, the learning curve is steep and while I am able to get data displayed, I still know very little about the program. Anyway, I decided that I could do this at another time and went outside and read for over an hour. It was great to soak up the sunshine and mild weather. In fact, it is still 61 degrees at 10:30EST.

It's been a while since I posted too. Blue Lightning, my car, went dead in mid-February. While it seemed like a starter issue, it ended up being a dead battery. The battery served beyond its like expectancy.

The above is a picture of the snowfall from Sunday night through Monday that brought snow from the Ozarks, Tennessee Valley, northern Georgia, Piedmont and the I95 corridor. Anyway, on the high res image (not this one, this is 1km resolution, the high res is 250m) you can see State College via the Bryce Jordan Center's white dome (basketball stadium for Penn State). Also, interesting to see the snow on the Delmarva peninsula. This article features one of the gentlemen I work with and also some data that he (and a little of me) sent them. Biggest Snowstorm of the WInter Sweeps Across the Northeast

I also was in The Times for an unusually balmy day. A cold front got hung up north of the city, which ended up causing my forecast of 43 to be 9 degrees too cool. Unusually Balmy Day Surprises Everyone, Especially Forecasters

That is all for now.

Snow (in State College)

Pennsylvania weather (above) late this evening (a band of snow (not related with the main storm tomorrow) over the eastern part of the state. Winter storm warnings (pink) and winter weather advisory (purplish) in effect early Friday to early Saturday.

It appears that within roughly 24 hours a blanket of 6 to 8 inches of snow will fall over State College. The 21z SREF does bring some concerns though. It has the rain/freezing rain/sleet/snow line further north over previous runs today. Compared to previous runs, it also lifts the snow out of the area whereas previous runs have had a longer length snow event. Also, the 12-hour snow probabilities has shifted the best probabilities north of I-80 (instead of previous 7 runs (3z/8 to 15z/9) around or just south of I-80). 50% probability of 4"+/12 hours are now northern Pennsylvania instead over the I-80 corridor.

As for the models, the 0z WRF would give us 7.6" of snow (with some ice pellets/freezing drizzle toward the end if the model is correct) and the GFS would give us 8.2". WRF has the low tracking near the PA/MD border, which is in line with the SREF. It appears, and rightly so given the trend of the heaviest precipitation being further north, that the band of snow will move into northern PA and then eventually reach the rest of the state as the low approaches and passes. The GFS is further north with the low's track.

I haven't looked at any soundings, but based on the 540 thickness (a rule of thumb meteorologists use to determine where the rain/snow line will be, although with any rule there are exceptions) it further north in the GFS compared to the WRF. That makes sense with the low track, but the BUFKIT text output indicates all snow in the GFS (granted the temporal intervals are not equal between the two models).

So, unless The State College Bubble Effect works it's magic or we mix, I think 6 to 8 inches looks good. Time for bed so I can watch the snow fall from our new office. Pictures to follow in a future post.

I need a 9 letter word for pain...nor'easter!

I've been sudo-off the last few days, but have been made aware of a potential disturbance this weekend for the big 3 (Boston, New York and Washington). 

I have just looked at the 27/0z GFS and the zone of low pressure will cross the Delmarva peninsula and be off the New Jersey coast by 12z/8AM Monday. This position is similar to the 26/12z CMC, but the CMC is about 12 hours faster. The ECMWF differs from both of these as the trough is not dug as far south as the GFS/CMC, which leads to a surface low crossing the western Great Lakes Sunday night (GFS forms a secondary low over the Great Lakes as the system occludes). If the GFS/CMC are the "correct" solution, the folks who live here say a track over Philadelphia means big snow in State College. However, will it be snow? 

At least for the big 3, it would seem it would be rain at this time. It appears (at least with the latest run of GFS/12z CMC) that the boundary layer (lowest ~1000ft) may be too warm as the low tracks too close to the cities and cold air is not currently in place over the coastal locations. 

In State College, we would end up with rain, then maybe some snow as colder air arrives. If this were the case, snowfall would be minimized, as depicted in the image below. If it were all snow, we could see a healthy amount. Obviously with the storm a few days out, there is lots of room to roam. Needless to say, a tricky forecasting situation the next 4-5 days.

0z GFS UNV precipitation type and amount forecast. Time goes from latest on right to next Wednesday on left. 

On the Edge

It turned out to be a beautiful fall day in State College and it wasn't totally expected. A low pressure system off the Middle Atlantic Coast was expected to keep clouds around east of the Appalachians, which includes State College. However, the satellite image from this afternoon shows that we just west of the cloud shield. This was likely due to sinking air. To create clouds, air has to rise and cool to saturation. All that rising air has to sink someplace, and we turned out to be in that "sink zone". Needless to say, forecasts for Boston and New York from the last few days have been difficult. I have learned a few things from these last two East Coast storms and hopefully will aid in the future. However, this forecast, like early last weeks that brought snow to the Poconos and Catskills, is not turning out well. Boston, though, appears to be a little bit more along the lines of what I had envisioned. I'll have to check when I return to work to see how it all verified.

As for today, it was a wonderful day off and I raked leaves in under mostly sunny skies and a temperature of 65 degrees. Then I came inside and sipped some hot apple cider. Delightful!