18z Model Thread 12/22

[yoda]

The 18z NAM is out to 12 hrs. It would appear that the s/w is a bit more consolidated then it was at 12z

[vinylfreak89]

for 6 hours thats a decent change... could be more significant down the line.

[yoda]

Big difference between 18z h5 at 18 and 12z h5 at 24 is there is now a more consolidated h5 low... not that weird two looking one at 12z

18z NAM at 18hrs h5

12z NAM at 24 hrs h5

[Jmister]

FWIW, 15z SREFs are much improved at 500mb over the 9z ones:

15z

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/sref/09/images/sref_50h_087s.gif

9z

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/sref/15/images/sref_50h_081s.gif

[jcwxguy]

seems to be stuck on hr 30

the differences at hr 30 (open is the 18z)

[Eskimo Joe]

FWIW, 15z SREFs are much improved at 500mb over the 9z ones:

15z

http://www.nco.ncep....ef_50h_087s.gif

9z

http://www.nco.ncep....ef_50h_081s.gif

15z SREFS have a lot more energy dropping south from Canada and it looks to be dropping dead south.

[jcwxguy]

at hr 36, 12z and 18z are almost the same, perhaps slightly slower and a hair south

at hr 42, nice jump south compared to 12z

[yoda]

At 42 hrs the s/w is further southwest then it was at 12z re h5. At 12z it was in the panhandle of TX, while at 18z its in extreme SE New Mexico

[Dalfy]

Northern stream energy looks more consolidated compared to 12z as well to my untrained Eye.

[jcwxguy]

closed off at 48 and 54 aqnd 60

[stormtracker]

Nam looks really good at 48...compared to 12..s/w energy is stronger and a bit farther s.w

[SNO]

Nam looks really good at 48...compared to 12..s/w energy is stronger and a bit farther s.w

Would this result in the storm riding the coast?

[usedtobe]

Nam looks really good at 48...compared to 12..s/w energy is stronger and a bit farther s.w

Yes it does.

[dg12x]

Nam looks really good at 48...compared to 12..s/w energy is stronger and a bit farther s.w

At quick glance...54hr looks to be a phenomenal improvement of 60hr at 12z

[goldstar]

Would this result in the storm riding the coast?

The model run is still ongoing, in the next few frames we should get a clearer picture with the off model run. tonights 00z run should hopefully give us a narrower range of outcomes, but one can never know for sure!

[jcwxguy]

at hr 60, the sfc low is off the southeast tx coast

[Dalfy]

54 major changes

comparison:

12z:

18z

Closed off low in central texas, Phasing starting to occur @ 54 18z and northern stream energy more consolidated.

[Midlo Snow Maker]

hr 66 is a huge step to the euro

[goldstar]

The ULL looks to be vacating a little faster as well, or maybe my eyes see incorrectly, that may be influencing the deepening?

[Terpeast]

FWIW, 15z SREFs are much improved at 500mb over the 9z ones:

15z

http://www.nco.ncep....ef_50h_087s.gif

9z

http://www.nco.ncep....ef_50h_081s.gif

Better height rises ahead of the trough on the 15z, which means the sfc low wouldn't be squashed out to sea as much.

[usedtobe]

The ULL looks to be vacating a little faster as well, or maybe my eyes see incorrectly, that may be influencing the deepening?

I think it shifting out a little quicker.

[Midlo Snow Maker]

hr 66 is sucking all the northern stream . 66 has a closed low over se texas huge change

[Eskimo Joe]

If we can get the surface low to actually go over the GOMEX for a bit, that should really juice the system up.

[Gibbsfreeenergy]

all positive trends on 18z nam vs 6z nam...more dug northern stream and higher H5 east coast..eastern ME vortex much farther north too.

[Eskimo Joe]

huge change? good or bad?

That is a good change for snow lovers. Midlo's post implies the northern and southern streams of the jet stream are combining, thus setting up a significant east coast storm.

[Midlo Snow Maker]

this looks promising

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/18/index_700_s_loop.shtml

[Gibbsfreeenergy]

all positive trends on 18z nam vs 6z nam...more dug northern stream and higher H5 east coast..eastern ME vortex much farther north too.

also add on sharper and slightly more amp'd and less progressive upstream ridge.

[thedude11]

Surface low in N GOM at hour 66.

[Gibbsfreeenergy]

18z nam 4mb deeper with sfc low in GOM vs 12z run even

[dg12x]

Gulf appears open for business @ hr 78.