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Friday, February 7, 2014

2-12 to 2-14

2-12 afternoon - Euro holds, a bit colder, GFS still in la la land.  18z NAM comes around to proper 850 temps and precip - brings 6+ to coast! 12+ inland!

2-12 late morning.  Last update due to travel.  All models show at least 6 inches of snow on their snow maps, posted below.  Short range models should be used going forward, but I won't be here!  I'm thinking 8-14 inches is doable in Danbury,  10-16 in Putnam, Orange, Dutchess and Litchfield Ctys.  6-10 in Westchester, NNJ (with Sussex 8-14).  Catskills perhaps 14-20 inches (despite models having them in the 6-10).  Biggest bust potential is higher along the coast. I'm still skeptical on how the NAM now, and the GFS handle the 850's.  Timing of the storm and type of precip is varying still run to run.  Sometimes a good dump on the front end, sometimes we are in the comma head and don't turn over (CMC/UKMET) and sometimes its a 4-5 in front, dryslot/rain, 4-5 on back.  Still a lot of details to work out, and this can still trend further west and bring mostly rain, but that chance is slowly dying.

2-11 Evening  - If you throw out the GFS, CMC, Euro and NAM all have a good snowstorm coming.  Euro as noted below has mixing issues, but has the most precip so a good thump of snow should proceed a turnover. NAM is cold, but drier, catching up though withthe 18z run.  CMC briefly has temps over 0 at 850, with NW CT and NY staying below. Below is warmest 850 and precip maps

NAM runs all look pretty similar and all areas stay snow.  0z run had less precip (.25-.5) , the 6.12 runs put down 6-8 inches on the snow map for most of the areas n or w of nyc as there is .5-.75 in our area and higher amounts to the east, with the 18z starting to have 8-10 inch amounts.   the 18z precip map is below -with 850's and the snow amounts look light.
18z nam precip

0z gfs runs low from east of OBX at 1004 to just east of ACK at 982 - great snowstor, qpf though is only .5-.75 for dxr, with a part of CT in 1+
6z gfs  runs low from OBX at 1000 to off Cape Cad at 976 .5-.75 precip
12z gfs runs low from just inside OBX at 1000 to over BM at 988 .5-.75 precip
18z gfs runs low from just inside OBX at 1000 to inside BM over ACK or MVY at 988 - .75-1"  This run is really juiced up with large parts of CT and NJ over 1.5
All runs have around 6 inches for dxr, though snowmaps are all different. 

18z gfs precip
2-11  Lunch

 Euro is a mix and match for most areas along the East Coast, with snow to rain to snow. Some points of reference which remain with temps at 850 below zero, and I mean barely below zero are Orange (Mass), Westfield (Mass), Poughkepsie, Sussex, Allentown. All these spots have over 1.0" qpf. Areas south of that line mix. Even Nashua and Worcester go over to rain for some time. Boston as an example has 850 temps near +7. However, most areas have a good front end snow and some extra back end snow. ISP has mostly rain, with some front snow and a 983 mb mslp. MTP with 982 mb and mostly rain, but even these sites have snow to start, its just too wide of a range to predict. ISP as an example goes from -2.5 at 12z to .8 at 18z, with .56" falling in that time frame. Complicating things for the Island are that surface temps are over freezing just about the whole event. BOS and ACK then have mslp of 979 at 12z Friday. Other points checked were Morristown, Somerville, Newark, NYC, Groton, BDR, ACY, HVN, BDL, and DXR (of course). All these had a mix at some point, all had above freezing surface temps at some points too. Take away is that the Euro makes this a really difficult forecast for the bulk of the population in the NE. Alot of everything

2-10   Looking at 6-10" - CMC/Euro v GFS.  Nam in good place, lacks precip *odd for NAM

0z  -Low from OBX to ACY, jog east then back  NNE, inside BM, 
12z LP from NC to 999 off delmarva,  inside BM around 988, right off CCod 984 to gulf of maine at 972.  Most of CT in the .75-1 inch with east CT in the 1-+1.25.  NJ big winner with 1.5+; PHL with 1.25.  850 temps marginal along I95 - PHL, Central NJ, LI, SE CT, RI and SE MA all get some rain. West and North of that line look for 8-14 inches.

0z - shoots ne off OBX, maybe a flurry
6z - a little further north, still too far to be trouble.  2-4 inches.  850s not an issue, except SE NJ.
12z - a little further north, from OBX to BM. This is a classic track for a noreaster and should generate a foot of snow for most areas N or W of NYC.  850s a problem for SNJ, LI, RI, SE CT and SE Mass.  The issue I have with this run is that it only produces .2" of precip for DXR.  Its not the fastest storm, and should produce more precip than that.  DXR in .25-.5 range for 3-6 inches, SNJ has nearly an inch, but much of that rain.
18z runs a bit further east than 12z, keeps 850's good for all but immediate shoreline.  a 988 low just SE of the BM.  Again, it lacks precip with most of CT in the .25-.5 range with the Easternmost sections at .5-.75 (but run risk of some rain there.). Delmarva gets pounded with precip, mostly snow.


0z with 996 low over E NC, heads north over Del Bay at 992, to LI at 988 to Gulf of Maine at 980.  A Ton of precip.  850s marginal except for NW NJ/PA and north of Orange Cty.  But most precip falls in favorable temp range as snow.  Snow map has widespread 12-18" snows NW of I95

12z same basic path as 0z, with a slight northwest trend for 850 temps, but still widespread 12-18" snow

12z nam
Only goes up to when the storm hits, but leaning towards Euro for placement, bt GFS for precip.
So the question is now how much will there be - CMC/Euro with 8-16", GFS with little or none, NAM looking good trackwise, but precip is light. Seems to light for a storm that strong, in that position. IF you go between the two, you get a mostly snow storm for most of the area, with 6-10 inches.  That is tonites call.


CMC 0z has low coming up coast and through the lakes.  Precip arrives thurs. Mix.  Storms phase to our NE on Fri
12z has storm a bit further east for snow on Thurs.  But precip is located more to the east of the center, keeping it light for inland, moderate for coast
0z brings low up (actually it looks like its coming from the gulf, but that system dies, another comes through and reforms over NC.  Low tracks just east of the Hudson, giving most in the tristate rain on Friday
6z - looks like cmc 0z. This time though the southern system does come around and up the coast, right position for a good storm but... A stronger northern LP over the lakes pumps warm air in and the 850s are not condusive to frozen precip.  Precip arrives thurs evening, lows phase fri aft in Nova Scotia
12z two 1004 lps, one from lakes, one from coast arrive together over NYC, but do nothing spectacular.  Rain starts thurs evening

12z has .3qpf starting 0z thurs with temps all below freezing all layers.  3-5 inches maybe.  ITs key is that the system rounding the trough comes up much faster.   Not a typical Euro error, but it is a typical GFS error. 

Gfs may be sending the first wave in southern stream  out too fast, breaking it in two.  Euro may be holding it back too much - those are typical errors.  Look for solution in the middle, leaning euro though.

2-7 Since the weekend storm is off the table, attention goes to the time frame of the 13th.

CMC 0z - shunts storm off south
CMC 12 - comes in a bit further north, but still just misses the tristate, brushing SNJ and SNE (sound familiar)
Euro 0z - ptype issues, low moves over nassau county, precip arrives by 7am
Euro 12z - a little faster, with precip arriving at midnite in CT.  Looks to be all snow at quick glance based on thickness, but its rather weak, precip from 1" near ACY to .5" along I95 and cuts off quick further north. For dxr .25"

GFS 0z  - runs OTS, but tries to create an inverted trough thurs night
GFS 6z runs 100mb low from OBX to just SE of BM, but precip isnt that much and it seems too warm
GFS 12z  has disturbance going way south, with LP  heading across the upper plains to WNY - warmer, with cold front passing on Friday.

NAM 18z - curiously has a system, albeit light, hitting VA with snow.
DGEX 6z slides that system to SNJ, follows with the one the EUro has right behind it and bombs it in the pocket, south of LI - takes it inside the bm, but is cold. 1000mb off NC, 984 S of LI to 976 E of Boston.  Its the most interesting, but is also the DGEX
Navgem - also has this system that NAM has, pops it off  the coast NE, but interesting to watch.
UKMET seems to want to go SE

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