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Posted by Ray
on 7/17/2008, 5:47 am
72.230.154.40
Although GFS and NAM suggest Saturday as slightly better than Sunday, I have close to zero confidence in that, as explained below. Being totally in agreement this AM with NWS Buffalo, here's their synopsis:
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 357 AM EDT THU JUL 17 2008
.SYNOPSIS... TYPICAL MID SUMMER WEATHER IS EXPECTED TO CONTINUE FOR THE REMAINDER OF THE WEEK AND THROUGH THE WEEKEND AS HIGH PRESSURE BUILDS ALOFT OVER THE EASTERN STATES. THIS WILL RESULT IN WARM AND INCREASINGLY HUMID CONDITIONS. IT WILL REMAIN DRY THE VAST MAJORITY OF THE TIME...HOWEVER ISOLATED TO SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS WILL AFFECT THE AREA ALMOST EVERY DAY.
Details: If an elephant is walking slowly towards you, you can fairly accurately predict it's position, speed, and direction of travel two seconds into the future. Not so for a chipmunk. The Rossby waves which encircle the globe can be huge, with one wavelength and amplitude spanning half a continent. And the larger the waves, in general the slower they move. In extreme cases, they can retrogress (go backwards), for example hurricanes (which sit under big Rossbys) go wherever the hell they want to...east, west, north, south. Conversely, very small waves, which one finds now in midsummer superimposed on the general zonal (east-west) flow (because the jet stream is north of us), are ephemeral, skitterish, difficult for the models to handle since their puny amplitude is sometimes little more than the uncertainties (measurement inaccuracies) in the model input (GIGO). As mentioned in previous discussions here, to resolve small-amplitude features (such as tornadoes or large thunderstorms), high-density data grids, and high-frequency model runs, are required, but prohibitively expensive. So, what you see is what you get: Hot, hazy, humid days with slight chance of electrons, and not much cooling off at night, since water vapor is by far the most important greenhouse gas.
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