Tuesday, December 16, 2014

Christmas time

12-25 - results: just under .5" rain with high temp of 61 around midnight.  Christmas day is currenlty 50 with NW winds 10-15mph

12-21
Afternoon  - 12z run of Euro has more realistic precip of under 2"  Actually, 12z GFS and 12z Euro not far apart anymore.


morning  Biggest question now is how much rain and flooding- below are qpf pics from now until Christmas night.  Most rain is over by 7am Christmas morn.

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Euro 1.5 - 4" for most of the area



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GFS 1.5 - 2" for most of the area


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JMA 1-2"
CMC/GEM 2-4"


ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho ho
12-19 East trend halted, still need to go further for snow.  Models not completely aligned with placement of low (upper and surface) yet.  Some pics of the differences from the 0z run effective Christmas Eve 7pm




Only the DGEX has the upper low going further south and east (and it actually moves to our south eventually, although its still too warm to produce meaningful snow)
Lastly, some snow maps for Christmas night - snow on ground or accumulated. Most of the snow on ground already exists .

Dgex snow

Euro snow

GFS snow




12-18  Still mostly if not all rain, but a shift east takes place, will the trend continue.

0z Euro transfers energy from lakes storm, to spawn storm over the EC.  This is similar to the 18z GFS run from yesterday.  This results in a 984 low right over us 7pm 12/24 and down to 976 over Portsmouth at 1am and 970 over Quebec by 18z 12/25.   No accumulating snow in our area.

0z GFS almost transfers into a new low, similar to Euro, but the GL low maintains control. 980 low over same area of Quebec, which then heads NW and deepens to 964.  Same for the most part on the 6z run

CMC  - more like Euro, storm develops on EC, goes to 984 over NYC and then bombs slowly northeast.  A little more chance of some snow on this run.  Can't tell how deep it gets as there are too many lines.  Actually its 977 off Tropical Tidbits, and it shows rain for the most part. 

DGEX 6z agrees with Euro, keeps the storms separate until it hits our area and gets pulled NW into the upper low.

12-17 Brown Christmas

0z GFS has 984 low over GL spawning secondary 980 lw over the east coast, too far west for us to have snow. It deepens  to 978 to our north and stacks with cold air flowing in.  Maybe some snow at the end. You know how often that works. 6z run is more traditional GL storm which gets to NY, but then is recaptured and heads back over the lakes as a 968 low.

Euro on the other hand sees the northern stream and the upper disturbance but it focuses more on developing a storm over MS and TN where it gets caught by the upper low and bombs to 972 as it heads N into the GL.



1217 0z gfs
12-16  With there remaining two events between now and Christmas, I'm separating the thread.  Christmas forecast is complicated with separate N and S branch systems.  The main character not forecast to enter US until Saturday/Sunday, so expect variation until then.

Todays Euro runs for Christmas - 0z has system entering WA on Saturday, then by Monday there is a 1000 slp over IA,  and another over CO, with a slug of moisture in the Gulf.  By Tuesday night, its 992 over WI, so it doesn't move much.  Meanwhile that slug of Gulf moisture starts moving across FL and over to the ATL. By midday Christmas Eve, there is a mess on the map with the slp over Lake Superior.  A lot of rain heading up the east coast. Snow moving through OH and Western and Central PA and NY State.  Then by Christmas morn the low off the coast forms over Cape Cod and up into Maine. Possibly snow showers for Christmas, otherwise nothing by rain.
12 run way different. It has a 998 slp over N Minn. on Monday, and Tues.  The slug of gulf moisture heads more over the SE, then on Wed a low forms over TN which moves to PA.  Looks like a 980 low over State College 6z thurs. Then it moves almost due east.  Looks like it stacks with an ULL, then moves SE after it passes us.  Amazingly has snow just to our north, but wow does it sock NH


GFS has another take.  0z run has slp stay north of the US, but send a bunch of moisture into our area Christmas eve, and the thicknesses look good.  A storm does form in the Gulf but it slides out to sea.  But... another storm forms once that moisture form the N Branch reaches us. A 996 slp forms over the benchmark.  So it snows a few inches/. 6z run is similar, but the gulf storm comes up coast further, we still get that moisture from the north. 12z run sends low to MN like 12z Euro, then spins it out. Secondary lp forms way off NC, then rotates into New England.
12z gfs
CMC has something in between

cmc


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