The Northeast Weather Blog...

January 2 coastal storm?

Posted by: Zachary Labe, 8:43 PM GMT on December 19, 2007

"Afternoon thoughts"
Good morning. Today a powerful cold front will move through the area with heavy rain and high winds. A wind advisory and some high wind warnings are out for all of Pennsylvania. Also the spc has highlighted central and western pennsylvania for a slight risk of severe thunderstorms. The will be a low topped squall line which will form and possible have some miniature supercells with some rotation too. This will also be something to watch. After the front moves through the lake effect machine fires up with snow in the northwest.

Severe Weather Outlook...
Squall Line...

"Short Term Forecast"
Currently here in Harrisburg it is 53degrees with low clouds (ceiling about 700'), light rain, and fog (visibility about 1.5miles). Today could be interesting across the state with a narrow band of extremely heavy rain and a possible embeded thunderstorm. We could see some very high winds with the frontal passage in excess of 50mph for a hour or two. Also dropping temperatures will result in a few hour period of snow across the western half of the state. Expect no snow across the eastern half. Rain totals statewide should be about 1inch. Snow totals from front should be about 1inch across the north and west. Also lake effect will begin after the front and drop several inches in typical snow belts.

*More updates coming throughout the day...

Weather Warnings...
*High Wind Warning* for central Pennsylvania
*Wind Advisory* for northeastern Pennsylvania
*High Wind Warning* for extreme northwestern Pennsylvania
*Wind Advisory* for western Pennsylvania
*High Wind Warning* for southern Poconos
*Flood Watch* for eastern Pennyslvania

Warning Map...

Radar...

"Christmas Forecast(longterm)"
Christmas looks to remain cloudy across most of the state with some flurries in the northwest and southcentral. Also throughout next week are chances for small precipitation chances with small fronts. Rain during day and snow during night can be expected. Highs will remain seasonable until this weekend with the next major storm. Many questions remain with that storm. Track will play a major part in precipitation types. Also the 12z run of the GFS shows a coastal storm on New Year's Day with snow affecting the entire state. This will be something to watch, because this is also when the NAO goes negative again. Check out this model run for the January 1 storm...
12z GFS model run for January 1

So here is my christmas day forecast...

Eastern- (Allentown, Southern Poconos)-
Mostly cloudy and cold. High 40. Low 27.

South Central (Harrisburg, York, Lancaster)(my home)-
Cloudy and cold. Passing flurry. High 39. Low 27.

Southern- (Philadelphia)-
Partly cloudy and cool. High 45. Low 30.

Central- (State College)-
Cloudy and cold. High 34. Low 21.

Northern- (Bradford, Williamsport, Erie)-
A few snow showers. (coating of snow)High 32. Low 21.

Western- (Pittsburg)
Cloudy and cold. A few snow showers. High 36. Low 26.

Johnstown, Altoona-
A few snow showers. (coating of snow)High 31. Low 23.

Here is todays NAO...
NAO...

**Just to throw out there...
The EURO model and GFS model have extremely different scenerios for the weather after about Wednesday. Personally I do not think we can trust either model. Also the GFS develops a relatively strong coastal storm on Thursday, but it stays far enough off shore not to cause an impacts. We still though should watch the track, in case of any changes will have a dramatic impact on the coastline of the middle atlantic and new england.

***Update as of 200pm
Check out that mean looking squall line near Latrobe, PA.
It developed right behind that small dry slot. The squall line will probably contain very heavy rain along with isolated gusts to 65mph. I will have continuing updates on the severe weather throughout the day across Pennsylvania.

MESOSCALE DISCUSSION 2260
NWS STORM PREDICTION CENTER NORMAN OK
0111 PM CST SUN DEC 23 2007
AREAS AFFECTED...CENTRAL/ERN PA...CENTRAL NY...NRN DELMARVA
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 231911Z - 232045Z
LINE SEGMENTS OF CONVECTION HAVE RECENTLY DEVELOPED IN WRN PA AND
WIND DAMAGE THREAT WITH THESE STORMS MAY INCREASE AS THESE LINES
MOVES EWD INTO CENTRAL/ERN PA...CENTRAL NY AND PERHAPS EXTEND AS FAR
SOUTH AS NRN DELMARVA. A WATCH ISSUANCE IS A POSSIBLE SOON.
CONVECTION IN WRN PA IS CURRENTLY LOCATED ALONG STRONG COLD FRONT
THAT IS MOVING RAPIDLY EWD THROUGH THE REGION. INSTABILITY IS
EXTREMELY WEAK...BUT ENVIRONMENTAL WINDS ARE EXTREME WITH 50-70 KT
WINDS LOCATED LESS THAN 1 KM ABOVE THE SURFACE. AT THIS TIME...THE
WINDS ABOVE THE BOUNDARY LAYER ARE PREDOMINATELY SLY...WHICH IS
PARALLEL TO THE N-S ORIENTED LINE SEGMENTS. HOWEVER...A 100 KT JET
STREAK LOCATED AT 500 MB WAS LOCATED OVER KY AT NOON AND IS FORECAST
TO NOT ONLY INCREASE THE MID LEVEL WIND SPEEDS...BUT ALSO AID IN
VEERING THE WINDS ABOVE THE BOUNDARY LAYER TO MORE WLY AND
PERPENDICULAR TO THE LINE SEGMENTS. THE WILL LIKELY ACCELERATE THE
LINE SEGMENTS MORE RAPIDLY EWD AND ALSO ENHANCE THE POTENTIAL FOR
THE STRONGER WINDS ALOFT/DAMAGING WINDS TO REACH THE SURFACE. THE
JET MAX IS FORECAST TO BE LOCATED IN WRN PA BY 21Z...WITH INCREASED
THREAT OF WIND DAMAGE WITH LINE OF CONVECTION MAY EVOLVE SOON.
DESPITE THE CONVECTIVE NATURE OF THE LINE SEGMENTS...THE WEAK
INSTABILITY MAY LIMIT THE VERTICAL DEPTH OF CONVECTION AND ONLY VERY
ISOLATED LIGHTNING IS EXPECTED.

**400pm Update
A High Wind Warning has been issued now for most of central Pennsylvania replacing the wind advisory. The squall line looks like it weakend but it may restrengthen when it hits 60degree air here in the central Pennsylvania area. Stay tuned for furthur updates through this afternoon and evening. Also I noticed light snow is being reported in Erie after they were at 53degrees earlier today. So there is a dramatic temp. drop off after the front goes through.

**800pm Update
Well the front blew threw Harrisburg PA with some trees and power lines down near Middletown. It is now windy with falling temperatures. Lake effect snow will start in snow belt regions as soon as the winds shift from the southwest to the west. Check out the model run for the 2 of January. It has a major coastal storm with lots of snow. This will be something to watch.
18z gfs model run for January 2

***Note***
This is the format I will give forecasts for the State of Pennsylvania for normal days unless a major storm is expected.
Afternoon thoughts, Short term, Long term, Just to throw out there, and last any updates needed

Categories: Weekly Forecast

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51. MDFirefighter 1:34 PM GMT on December 24, 2007
Accuweather forecast for me: Wednesday Night, Jan 2 Low: 14 °F RealFeel®: -13 °F Windy and frigid with snow Thursday, Jan 3 High: 32 °F RealFeel®: 13 °F Very windy; cold with snow much of the time BRING IT ON!!!!! lol Member Since: February 11, 2006 Posts: 1 Comments: 1201

52. Alleyoops 1:53 PM GMT on December 24, 2007
Santy Claws iz coming tonite...I iz watching for him... Have a MERRY CHRISTMAS Member Since: April 18, 2007 Posts: 185 Comments: 29166

53. dean2007 2:06 PM GMT on December 24, 2007
Snowstorm for the coast is all I'm asking.

54. Zachary Labe 3:06 PM GMT on December 24, 2007
Yes I think the possibility of a coastal storm is high for the first week of January. All the ingredients are there except for the NAO. I am anxious to see the 12z gfs. I will post a new blog later this morning. Member Since: December 14, 2007 Posts: 253 Comments: 14306

55. Zachary Labe 3:07 PM GMT on December 24, 2007
Also does anybody have a link for the european model? Member Since: December 14, 2007 Posts: 253 Comments: 14306

56. MDFirefighter 3:08 PM GMT on December 24, 2007
isn't the NAO forecasted to go negative around the 1st of the year? Member Since: February 11, 2006 Posts: 1 Comments: 1201

57. philliesrock 3:08 PM GMT on December 24, 2007
Here: Link I used to use the other sites, but forget them. This is the best one. Member Since: June 29, 2006 Posts: 65 Comments: 3197

58. philliesrock 3:13 PM GMT on December 24, 2007
Hope for a coastal storm in 3 days? Member Since: June 29, 2006 Posts: 65 Comments: 3197

59. MDFirefighter 3:19 PM GMT on December 24, 2007
Looks like the Mid-Atlantic could see some snow on the 31st. This is the 12z Euro Model Member Since: February 11, 2006 Posts: 1 Comments: 1201

60. Zachary Labe 3:21 PM GMT on December 24, 2007
Thank you. I am going to post a new blog shortly with lots of information on the long term cold and storm chances. Member Since: December 14, 2007 Posts: 253 Comments: 14306

61. Zachary Labe 3:23 PM GMT on December 24, 2007
MDFirefighter- you bring up a good point. yesterday I was looking at a gfs model run and it showed a coastal low on the 31st. Then the next run it disappeared. Maybe the models are onto something. Is that 12z model for todays 12z run? Member Since: December 14, 2007 Posts: 253 Comments: 14306

62. MDFirefighter 3:29 PM GMT on December 24, 2007
looks like it was yesterday's. i took it from the link that philliesrock posted. from looking at the GFS model, it shows rain for all of MD, DE & most of PA & NJ, but the Euro is showing snow. Guess we'll have to wait and see as we get closer. these models have been all over the place recently. Member Since: February 11, 2006 Posts: 1 Comments: 1201

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Cornell University- Atmospheric Sciences Student; Central PA SKYWARN Storm Spotter; American Meteorological Society Member; PA CoCoRaHS Branch Member

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