Month: February 2014

Cold & Stormy Late February into Early March

Miguel Pierre Long-Range Discussions

After some moderation with temperatures this week, the ECWMF, GFS and CMC ensembles are showing +PNA/West Coast Ridge for the last week of February. This will produce a mean trough over the Eastern US again with colder temperatures. Also note the Polar Vortex centered over Baffin Island:

12zECENS500mb12zGEFSf20412zCMCENS500mbf240The 8-14 day NAEFS shows 80-100% probabilities for below normal tempartures, for the Eastern half of the US:

NAEFS8-14dayPersistent warmer than normal sea-surface temperatures, have resulted in a resurgence of the ridge over Northeast Pacific region, since the fall. As of Feb 15th, the warm SST anomaly remains:

215sst.daily.anomThe latest ECMWF and GFS ensemble forecasts have the MJO going into phases 7 and 8 at end of this month. Which support the +PNA at end of this month into March.

ECMF_phase_MANOM_51m_fullNCPE_phase_21m_full

Currently analysis of 200mb vector wind anomalies show strong easterly jet over the Tropical Pacific. Which support the MJO propagation into phases 7 and 8.

current_anom_200windEvery time we’ve seen the -EPO/+PNA pattern reload, we seen a winter storm of at least moderate size. Models do show storms off and on, beginning next week. But the one that has most interested in is on Feb. 26-27th. The GFS and it ensembles have featuring this threat for possibly a Nor’easter. Several members show amplifying trough or closed low over the Eastern US, with a big ridge over the Northern Rockies.

12zGEFS500mbf276

12zGEFSslpf276To conclude, I think we are seeing the pattern cycle repeat itself, every few weeks, since November. However, the ensembles keep the Polar Vortex near Baffin Island. So while temps will average below normal, I don’t expect to see the extreme cold we saw back in January. There will be winter storms between the end of February and into first 10 days of March. But how large each of them will be for the area, will depend on the position +PNA/West Coast Ridge axis or the amount (if any) blocking on the Atlantic side.

Snowstorm 2/15/14

Miguel Pierre Forecasts, Winter Wx

Models have been trending stronger and NW this system. Particularly with closing off 700mb and 850mb lows near our area. The GFS has been leading way in these trends. The 0z run tonight back a little bit from it’s 18z run. Which would given NYC around 6″ of snow and  LI and CT 6-12″ of snow. But it still more amplified than the 12z run. The 0z UKMET and ECMWF has also come in further west tonight. So my forecast will follow the 0z GFS closely. Note that initially BL temps may be warm enough for some mixing or melting at the start. Especially over LI. So this may cut-down to the low-end of these ranges.


Snowfallmap21514

2/13/14 Nor’easter Snowfall Wed PM Update

Miguel Pierre Forecasts

New snowfall map is below. The model guidance has shifted the track surface and mid-level lows further west. This means more warm air likely be able work inland. So heaviest snowfall will be falling just north and west of I-95 corridor. Snowfall basically to come two waves:

1. As warm air tries to surge in, a TROWL/strong coastal front, will be developing late tonight. Models are strong vertical velocities tomorrow morning. That could result in snowfall rates 1-3″ per hour. Some thunder and lightning is not out of the question either. After these bands move through, many coastal areas will either changeover to sleet, rain or drizzle.

2. CCB (cold-conveyor belt) will be developing later tomorrow, as the storm bombs out near out latitude. Model guidance is tracking the storm over Eastern/Central LI. So the CCB will likely be stronger with more significant additional accumulations for Western sections of the area. While Eastern areas may pickup additional 1-2″. This will have monitored closely tomorrow.

SnowfallmapWed