February 27, 2003
12:45PM Update in RED
Not much change to the forecast but with successive model runs continuing to lesses precip amounts in the area, and based on radar trends, will hedge snowfall totals down. Timing hasn't changed but snow amounts will be closer to the 2-5" range with isolated 6" amounts. Confidence is now average with the forecast. It's still odd to me that guidance is lowering precip amounts, yet each run, the area of low pressure has been closer to the coast and farther North. Normally, this would sound an alarm that we are in for a surprise, but with all guidance now on the same page, 2-5" is a good bet. We should not get into and *heavy* snow either with this event. More light snows Saturday night into Sunday with another update late tonight. Take care!
Someone once asked me a long time ago, "Steve, is the science of weather forecasting, especially during the winter season, really as difficult as you forecasters make it seem"? My response of course was something along the lines of, "Why not at all, and that is why we are always right". Needless to say, much pun was intended with that statement. Truly, coming together with a solid forecast for a storm system during the winter months, especially in the big cities which lie near the coastal plain, is very difficult indeed. Even with the progress that the science has made and the amount of money that has been poured into computer models and the like over the years, forecasting a winter storm is, in my humble opinion, the most difficult forecast of all to make.
That being said, we are in for one heck of a forecast struggle over the next 24-36 hours as computer guidance has been anything but consistent from run to run. Actually, of the "Big 3" in short range (NGM, ETA, GFS), there seems to be more of a spread now than earlier today. Actually, the NGM and ETA models are very supportive of each other FINALLY, but the much touted GFS seems to be in a world of it's own giving the area nothing more than a coating of snow during what appears to be a significant snow even Thursday night into Friday midday. On the other hand, is it possible that the GFS is actually the one model with the right idea? I honestly doubt that as the model diagnostic discussion from HPC has noted several errors in it's initialization.
Right off the bat I will tell you that confidence in this forecast is very low, and this is not just coming from this website. Forecasters from the NWS have even stated that this is quickly becoming one of the toughest forecasts for the entire season. So, with that said, I have taken a blend of the GGEM/ETA/NGM (and UKMET to a degree) as well as some extrapolations in the current observations and precipitation fields based on tonight's 0Z progs. Here goes....
Thursday will start off mostly cloudy with scattered flurries, especially South of the city. Highs in the mid 30s. Thursday night will be cloudy with light snow breaking out around 8 or 9 PM starting from areas South and then progressing Northward. Snow will be relatively light but should intensify as the night progresses. Not quite sure if the snowfall will reach "heavy" status in Philadelphia, but nonetheless, there will still be accumulating snows. Lows Thursday night in the upper 20s to around 30. Although earlier today it was looking like a change to or a mix of snow/sleet/and rain was likely, I am slowly backing down from that idea. Places South and East of the city should still see a mix later Thursday night for a period, but PHL to the North and West *should* remain all snow for this one. Friday starts off with snow and maybe a mix especially South and East of the city. The morning rush should be a mess on Friday, so if possible, you may want to consider a long weekend at this time. Snow tapers to flurries and snow showers midday Friday with partial clearing by late afternoon. Highs Friday around 36. Total snowfall in and right around the city itself will be around 4-8" with a few isolated 9 or even 10" totals!
As stated earlier, confidence in this forecast is at an unusually *low* level and with this type of storm system, a distance of only about 20 miles could make a MAJOR difference in what type of precip you get and just how much. A shift of the storm slightly South and East (and I do mean slightly) and the area sees nothing more than very minor accumulations (unlikely at this point). If the system tracks a bit farther North, we could get in on some of the very heavy snowfall that DC and BWI are likely to see (8-16"?). If the system goes just a shade farther West, we get a heck of alot of sleet mixed in with lower accumulation. For now, will stick with 4-8" with little mixing here with the heaviest band of snow falling on a line from DC to Baltimore into Central Delaware and across the Chesapeake into the Southern portion of New Jersey. Keep in mind, although the heaviest band will set up along these areas, the mix line will be VERY close by, so this does not necessarily mean these areas will see the most snowfall.
Anyway, before I get too sidetracked, snow will spread into the region Thursday night and continue until midday Friday. Some mixing with sleet is likely especially South and East, but I am not expecting much of a mix in the city and points North and West. Total accumulations ranging from 4-8" with some isolated 9 or even 10" totals, especially South of the city. And if that isn't enough, it looks like another disturbance is poised to bring even more light snow to the area Saturday night and Sunday. Another update around midday Thursday to do some tweaking. Take care!
S.B.
