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Tracking the Late October Potential


stormtracker

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"The story begins on the evening of November 10, 1987. A cold high pressure for the time of year was to the north of the D.C. area, while a weak 'upper air disturbance' was forecasted to pass to the south of D.C .overnight which would include the D.C. area in the northern fringe of its limited precipitation shield. The term 'upper air disturbance' was years later confirmed by a University of Maryland climatologist to me as being what I had suspected all along: that the meteorologists don’t know what it actually is and that it is 'up in the air' and is indeed a disturbance since it is producing cloudiness or precipitation, hence the term upper air disturbance. The local National Weather Service (NWS) as well as every local news meteorologist including Bob Ryan of channel 4, Sue Palka of channel 5, and Gordon Barnes of channel 9 predicted flurries for the area that night. The fact that the local news meteorologists went with the NWS is of no surprise because they rarely deviated from the others and actually stated what they were thinking, if anything."

See http://localnews.col...erans-day-storm

Actually, Brain Korty of HPC put a forecast for 2-4 inches out prior to the event but none of the local forecasters bought because it was based on then brand new NGM. They were relying more on the LFM and old AVN.

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NAM's been moving west and GFS was the first model to bring it west, so yep, GFS, as of now, looks to score the coup

unless the guidance is really wrong across the board, I think the big question is what to do with the elevated suburbs 20-30 miles NW of the cities...like Germantown/Leesburg.....That is the trickiest area....Do they get some nuisance wraparound that maybe coats the deck and grass or do they get a wet pasty bomb like the NAM is showing?.....

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unless the guidance is really wrong across the board, I think the big question is what to do with the elevated suburbs 20-30 miles NW of the cities...like Germantown/Leesburg.....That is the trickiest area....Do they get some nuisance wraparound that maybe coats the deck and grass or do they get a wet pasty bomb like the NAM is showing?.....

That is, the NAM actually shows a dry slot on its sounding at 18Z. look at how dry it is above around minus 8 o 10C. That's not a great snow sounding and often is a drizzle one.

post-70-0-03118400-1319832960.gif

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15z SREFs not as bullish with QPF... looks like easily 1"+, but the 2" contour from the 09z SREFs is gone (besides a very tiny 2 in S PA)

It looks like it still takes the h5 low south of us through RIC then just SE of us I believe

It's not full cold season yet but we don't usually get 2" QPF winter storms

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"The story begins on the evening of November 10, 1987. A cold high pressure for the time of year was to the north of the D.C. area, while a weak 'upper air disturbance' was forecasted to pass to the south of D.C .overnight which would include the D.C. area in the northern fringe of its limited precipitation shield. The term 'upper air disturbance' was years later confirmed by a University of Maryland climatologist to me as being what I had suspected all along: that the meteorologists don’t know what it actually is and that it is 'up in the air' and is indeed a disturbance since it is producing cloudiness or precipitation, hence the term upper air disturbance. The local National Weather Service (NWS) as well as every local news meteorologist including Bob Ryan of channel 4, Sue Palka of channel 5, and Gordon Barnes of channel 9 predicted flurries for the area that night. The fact that the local news meteorologists went with the NWS is of no surprise because they rarely deviated from the others and actually stated what they were thinking, if anything."

See http://localnews.col...erans-day-storm

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That is, the NAM actually shows a dry slot on its sounding at 18Z. look at how dry it is above around minus 8 o 10C. That's not a great snow sounding and often is a drizzle one.

post-70-0-03118400-1319832960.gif

I'm more curious about Upper Moco and Loudoun prior to 18z when we are getting pounded.......This is Ji's backyard at 15z....looks like he is getting raked

post-66-0-98743700-1319833488.png

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This will be a leesburg - frederick - westminster, york, philly etc special. north and west of those areas will see the heaviest precip and some snow...we stand a really good chance of getting a dry slot during the height of the storm with a brief shot of some mix at the end as the storm pulls off to the northeast...

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I'm more curious about Upper Moco and Loudoun prior to 18z when we are getting pounded.......This is Ji's backyard at 15z....looks like he is getting raked

post-66-0-98743700-1319833488.png

I think that's true but he needs to get it fast, his sounding also do not show quite as pronounced drying aloft or their sounding is just colder so even with the drying they can get nucleation.

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euro is drier and warmer overall....If I lived in Leesburg at 500', I would be much more flexible with my expectations

There might be a big difference between just west of leesburg where elevations go up to like 600 feet and the town and parts east near the river. I am counting on my 1000 ft elevation to help me a lot with this. Still skeptical even up here but I think the ground will at least get white and I am totally happy with that for October.

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hr 27 and 30 of the NAM close up on ewall show interesting stuff in C MD as a bit of a deform band hits the area it looks like. 850's -3ish and sfc temps 34-35 it looks like. .5-.6 hr 27, .2-.3 more hr 30.

yep, and that's been our saving grace on the NAM for the last 3 runs including this one

it's a nail bitter and probably a nowcast like we've never seen before on this Board

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I think that's true but he needs to get it fast, his sounding also do not show quite as pronounced drying aloft or their sounding is just colder so even with the drying they can get nucleation.

yes...looks like the drying happens pretty rapidly late morning to early afternoon.....How much do you think the lower levels from say 925mb down to the surface will matter for someone like Ji or say Germantown?.....it looks like above that is pretty solid by early morning or even before

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