NYC/PHL 12/21-12/27 Forecast Threats

[SnowGoose69]

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I find it interesting how the GFS and Euro seem to completely switch places on who's most bullish with the storm.

The change too place at 0z last night, and I wonder what causes this because it happens often.

It might just be the fact the GFS if you ask me is a better model in general than the Euro beyond 180-190 hours as it can often better decipher that big events are going to happen or sometimes can even place them correctly...of course it often places Cutters too far east in that range but otherwise I think its better than the Euro....thereafter the Euro is a better model from 96-160 or even 180....inside 96 usually there is agreement but sometimes the GFS or Euro can hold out on the other.

[tornadojay]

that little shortwave moving through Minnesota is pretty potent.

[tombo82685]

that little shortwave moving through Minnesota is pretty potent.

i know, to bad the confluence has it for dinner

[Sampson]

that little shortwave moving through Minnesota is pretty potent.

If the s/w is more organized, would that aid in slowing everything down thereafter?

[tornadojay]

If the s/w is more organized, would that aid in slowing everything down thereafter?

well, i'd say we'd certainly wouldn't want to lose the presence of the 50/50 low off the north atlantic coast. I think we wanna get that shorwave out of that region and let the heights build out west to amplify the pattern and have the ensuing trof in the east dig a little bit more.

[Stormlover74]

At this point this GFS run is rather meaningless for me. I mean if it shows a mega blizzard is anyone really going to get that excited unless the other models back it up? And if it shows a miss I'm not really going to be too concerned either. I'm much more interested in the Euro to see if it can show a similiar solution as it did last night

GFS initialized...here we go............"crosses fingers"

[Collegestudent11]

Is it called a 50-50 low based on the latitude and longitude?

[IsentropicLift]

At this point this GFS run is rather meaningless for me. I mean if it shows a mega blizzard is anyone really going to get that excited unless the other models back it up? And if it shows a miss I'm not really going to be too concerned either. I'm much more interested in the Euro to see if it can show a similiar solution as it did last night

I'm much more interested to see if the two of them can come into better agreement. I'll get excited if the GFS shows a mega storm if it follows the same synoptic reasoning. All I'm looking for here on this run is to see if the timing can slow down a bit and hold the energy back more in line with the EC.

[tornadojay]

Is it called a 50-50 low based on the latitude and longitude?

yep

[am19psu]

Is it called a 50-50 low based on the latitude and longitude?

Yes. Same thing with the 40/70 Benchmark.

[Collegestudent11]

I always wondered where it came from, i initially figured it was something at half strength, or more like an occluded low pressure system, which most probably are.

Also, i learned in one of my course that an occludded low is when the cold front over takes the warm front. Does that happen due to the fact that the storm is losing energy, or rather that it becomes too powerful and tight that it cannot keep the two separate.

[Sampson]

well, i'd say we'd certainly wouldn't want to lose the presence of the 50/50 low off the north atlantic coast. I think we wanna get that shorwave out of that region and let the heights build out west to amplify the pattern and have the ensuing trof in the east dig a little bit more.

Ok..makes sense. Thanks for clearing that up for me.

[Stormlover74]

Exactly. I dont think it helps us if they both show us getting a big storm but with a completely different setup

I'm much more interested to see if the two of them can come into better agreement. I'll get excited if the GFS shows a mega storm if it follows the same synoptic reasoning. All I'm looking for here on this run is to see if the timing can slow down a bit and hold the energy back more in line with the EC.

[tombo82685]

12z gfs looks like its a little slower so far

[Isotherm]

Out to 48hrs the playing field getting set-up w/ our 50-50 low and west based block over nern Canada.

[tornadojay]

man.. what a bad time for a conference call at work.. oh well.

[tombo82685]

man.. what a bad time for a conference call at work.. oh well.

tell them it has to wait, the 12z gfs is coming out

[am19psu]

The new reforecast ensembles still aren't great, but it may be a GFS-initialization issue, since the 0z GFS was so off.

[tombo82685]

hr 81, has a sub 1008 low in northern tex

[ARyan]

I always wondered where it came from, i initially figured it was something at half strength, or more like an occluded low pressure system, which most probably are.

Also, i learned in one of my course that an occludded low is when the cold front over takes the warm front. Does that happen due to the fact that the storm is losing energy, or rather that it becomes too powerful and tight that it cannot keep the two separate.

The Norwegian Cyclone Model explains how mid latitude cyclone works best. A front will occlude and cyclone will fill in eventually, it's inevitable. You need to keep evacuating the column of air in order to maintain the low pressure, once that ends, the column will fill in.

http://www.srh.noaa.gov/jetstream/synoptic/cyclone.htm

[tombo82685]

through hr 87 the gfs is pretty close to the euros low pressure spot. Gfs has a sub 1012 low over north central tx

[IsentropicLift]

through hr 87 the gfs is pretty close to the euros low pressure spot. Gfs has a sub 1012 low over north central tx

Looks very similar to the 09z SREF at 84hrs

[tombo82685]

a good bit less amplified than 6z, northern stream is still separate

[tombo82685]

northern stream starting to get into the picture at hr 108 with a 1012 low ove east central miss/west central ala border

[Allsnow]

trying to phase hr 111

[tombo82685]

lgt precip into dc and just about to lancaster pa at hr 114

[tombo82685]

storm is really slowing down waiting for that northern stream to phase in at hr 117..

[tornadojay]

this thing is definitely digging down deep.

[tombo82685]

hr 123 has a sub 1008 low over siuth central nc lgt precip just into phl

[tombo82685]

hr 129 sub 1000 on hse