Wednesday, December 12, 2012

White Christmas watch

12-26 - had inch of snow fall Christmas Eve, making it a white Christmas.  Also had flurries early in the day.

12-12  White Christmas, defined as having snow on the ground. Will also include whether a storm will be in the area on the 24th or 25th.

GFS 0z ,6z 12z run has white christmas.  No storms in the period.


Dec 16-20

12-14 - Looking like rain (At least this morning)

Morning - Still no consensus whether its model to model or run to run of each model.   Can't even tell if its a big or small storm let alone rain or snow.  There will be precip though.

Euro - storm heads to Michigan, peters out on Sunday. Snow to start, quick change to rain.  No transfer to the cost.  Storm forms TN, rides through WV to off ACY (988) overnite Monday.  Heads over LI and N into CT as 988 low on Tuesday out to the Cape Tues nite.   All rain except the beginning and end.  Ensembles are east of the operational with the storm over the BM and temps close to snow. 

0z gfs - Rain sunday as low heads to UP of Michigan.  It never really transfers and forms secondary until Monday afternoon and that is to our east.  Wednesday's storm is out to sea, with a inverted trough bringing some snow to the area.  Ens has front end snow (briefly) and transfers off  to a 1005 low near the BM Monday night.  Next storm forms over SC on Tuesday VA coast Tues night to just inside the BM with snow falling west of the Hudson and in NW CT. Snow falls lightly on Wed in the entire area, but not much.

6z GFS - rain on sunday as low peters out over Michigan and secondary forms off Monmouth cty.   Rain is fairly light and cold.  Clears out Monday afternoon as a broad area of low pressure runs from Canada to TN - which then starts to form a new 1000mb low over OH - this is much further north than any previous run. That low slowly moves over the metro area, going to 988 basically right over DXR.  The SW area of the low has snow over NNJ.  The low tracks due east along the CT coast with all types of precip, albiet lite. Ensembles mean does have the transfer and it moves over the metro area then east.  Has it over BM on early Wed morning

UKMET has low heading to MI, reforming in S. Ohio, then heading just to our NW.
CMC on AWPRO is a mess - can't tell whats going on there but eventually a low  forms of OBX and goes near the BM on Wed.   RGEM does start as some light snow, quickly turns to rain on Sunday.  Main low stalls over Lake Superior, secondary tries to form due south off NC.  A second secondary forms over Indiana and both secondaries move north. By Tuesday morning, the coastal secondary fades, the inland secondary is 994 near South Bend. By later in the day, that low peters out and a coastal secondary secondary forms well offshore by 1pm on the 18th.  That low moves NE to the SE of the BM while another low forms South of LI.  Model only goes until Tuesday night. The CMC on the Ewall takes over at hr 132 with a low near the BM and snow across the area.

DGEX - has low close to us, but is too cold and shows rain turning to snow.


12-13 -Still looking strange - there will be a storm, somewhere, sometime, but which storm takes over is still in question.

0z ECMWF has completely different look  than yesterday.  Third storm - much weaker low starts off OBX at 998, tracks east, then north just east of the BM, not bringing much precip, but keeping it colder. So it loops east, then north, then northeast to get to the BM, and its 976 by the time it gets there.  IT also has a stronger (than previous run) secondary storm going off OBX  to just SE of the BM on tues - looks like its 996mb, so it doesn't generate enough cold air for snow, but the 850 line is just to our north. 

CMC 0z has it snowing from Sun-Thurs as multiple lows pass through with the strongest a blizzard on thurs.

0z GFS Pushes "warm" front through Sunday night, no real precip.  1004 secondary forms around the BM, but the 540 rain snow line is well into NYS and central New England monday night.  Meanwhile monday night has a weak 1000mb low over the NC VA border going to 992 off SNJ, to 988 s of LI, to 984 over the CT/RI border.  Too close for snow at first.  But it stalls over CT/RI and the cold air catches up.  But the precip is winding down as the storm has occluded by then.  It then heads SE to the BM and out to sea.  Maybe some snow on the back end for CT, interestingly, C and S NJ get snow.

6z GFS loses it.  A weak 1000mb storm over the UP of Michagan, degenerates.  There is no transfer to the coastal for a secondary and there is no third storm.

12-12 evening

Normally the Euro as shown is a blizzard.   But it tracks up the coast then east.  Yes at this frame we are getting snow, but not a blizzard. 


12-11

A really complicated and confused pattern is evolving.  We are going from seeing storms cutting to the lakes on the 17th, to forming secondaries to our northeast, to secondaries over us, to secondaries over the SE and then back to over us, or just flat out moving east once they get to the lakes.  Most runs of the GFS showing that these first series of shortwaves are weak, and either over us or to our north resulting in perhaps some front end frozen precip, but mostly light rain.

UKMET has straight run to the lakes, CMC is showing a transfer in New England, but with some front end light snow.  Euro is more complicated-  the storm gets to the central Lakes, dies and another reforms near the TN Valley, to W Virginia, goes to a 988 low over Sandy hook, then to ACK.  Only northern sections of CT and HV get frozen, and its only marginal.  DXR may see some front end and back end  - Euro has about 3 inches from this.

Then a second storm is trailing for the 19th.  The Euro takes it from the TN Valley, to a 988 low off Delmarva, goes to 980 over Cape May (due north??) with rain for most of Tristate.  Then it moves off ACY at 976 and the snow line moves into the Tristate with all but the coasts and LI turning to snow.  Below is the resulting snow map

However, the GFS is having none of this.  The 0z run had a similar 976 low south of the benchmark, but the rain snow line is back from central vt, to ROC, to OH.  Way too warm for that set up. Eventually the snow would move in, but very late.  It bottoms out in the 960s as it pulls away - note and intensifying storm creates its own cold air, so have to throw that run out temp wise and probably strength wise.  6z run starts weaker, keeps the snow line to about Albany. But as it intensifys off the coast to a 972 low, it moves SE (???) and still keeps the snow line from coming in until the end.

12z GFS just in and it brings the second low across VA (996) to over Chesapeake (990), over S NJ (984), NYC (980), then due east out to sea.  No snow at all locally, but ski areas get it good.   I think the strength is more appropriate, but the track is too close to NYC for any snow, despite the storm deepening. 

Storm 3 - could be the one! (spoiler, it was)

 2/9  Set up is an upper low over TX that heads northeast into TN valley and then transfers off the coast. At the upper levels, there's ...