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About heavy_wx

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  • Location:
    State College, PA

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  1. Looking forward to the first 80s of the year up here.
  2. Looks like we mostly avoided a freeze in the State College area.
  3. I saw quite a few small trees down around here. My power went out last night during the squall; it was still out when I left this morning.
  4. Well 0-1 and 0-3 km helicity are very high later in the afternoon so with some instability you can always get QLCS tornadoes.
  5. Some breaks in the stratocumulus here to the east but not much sun so far. We'll need pretty substantial surface heating to realize any discrete supercells later on, as the mid-level lapse rates are not that impressive on the 12z soundings from PIT and IAD. Most guidance is pretty optimistic for a QLCS during the early evening in central PA with strong forcing ahead of the cold front, and we could see some strong gusts with 60+ kt 850 mb winds mixing down.
  6. Mostly for entertainment, here is the 3km NAM for a point in Clearfield County Monday afternoon. Always interesting to see > 500 m^2/s^2 0-1 km SRH and > 1000 J/kg CAPE in a forecast sounding.
  7. There's certainly a good amount of low-level moisture in the western half of PA with dew points in the low to mid 60s. Deep layer shear looks pretty impressive for tomorrow as well as some curvy 0-3 km hodographs. I think the biggest issue (per usual in the northeast) will be whether sufficient instability will be present ahead of the convection. One potential issue is how persistent the easterly flow near and east of State College will be, where low-level clouds could limit instability. You can see that there's currently a backdoor front somewhere in eastern PA with temperatures in the low 60s to low 50s and dew points in the 40s.
  8. Some small snowflakes falling here this morning.
  9. Pretty cool seeing the back-door front come through here; the temperature dropped from low 70s to mid 50s and the winds picked up and shifted to northeasterly.
  10. The Euro has the pressure "only" down to 987 mb 12z Tuesday when it will be affecting our region; it does drop to 973 mb once it reaches coastal Maine. As you can see in the NARR image the superstorm had SLP values in the 970s over the mid-Atlantic. The pressure gradient was therefore much stronger during that event over central PA than the forecasts for this storm. Because of the early phasing, the storm was quite intense all the way up the east coast, producing heavy snow and blizzard conditions from the southeast to New England.
  11. Yeah, this is not March '93. That storm had a full phasing of the northern and southern streams over the southeast US.
  12. The 00z Euro had significant differences with respect to yesterday's 12z run in how close to the region the easterly 700 mb flow component gets. That difference seems to be a consequence of how much interaction there is between the primary low and the shortwave moving through the southeast. I would want to see how that feature plays out in future guidance to get a better sense of the potential for more intense banding over the northern and western parts of the subforum. Even the region north of I78 had substantially less QPF on the 00z GFS and yesterday's 12z Euro compared with last night's 00z Euro.
  13. It will be interesting to see how wrapped up the system gets as it intensifies off the mid-Atlantic coast. The 12z GFS has more interaction compared to the 12z Euro between the 500 mb low over the Great Lakes and the shortwave over the southeast, leading to a more intense system closer to the coast. As a result, the enhanced easterly 700 mb flow reaches farther inland and leads to stronger banded precip over eastern PA. We would have to watch the dry slot in this scenario given the stronger dry air intrusion that would occur with a more wrapped up system. In contrast, the 12z Euro has less interaction between the two 500 mb features and thus a weaker and farther east track. Most of the heavy precipitation depicted by that model occurs closer to the low pressure center than in the GFS depiction. I will be in the DC area for a conference during this event and thus in the strange position of rooting for the mid-Atlantic to get hit.
  14. I've seen a lot of references to the Kuchera snow ratio, but there's nothing published about so I have no idea if it is an improvement over 10:1 or not. Forecasting snow ratio is difficult because you have to account for snow growth, aggregation, riming, and melting throughout the atmosphere as ice particles fall to the ground. Probably the easiest way to estimate snow-liquid ratio is to start with climo, adjust upward if there is a favorable region for dendritic growth, adjust downward if temperatures are colder than -20 degrees C or warmer than -12 degrees C throughout the profile, and adjust downward if there is any part of the profile close to freezing. Here is a map of snow-liquid ratio climatology for the US: http://www.eas.slu.edu/CIPS/SLR/slrmap.htm
  15. It's associated with deformation at 700 mb increasing the thermal gradient (i.e., frontogenesis) and producing lift. I haven't measured the snow accumulation here, but there is noticeably more snow on the trees now compared to before the band was over us.