Revised Snowfall Totals for Jan 17,18th 2009

After reviewing the 00z model guidance and noticing that QPF totals were cut down ..I decided to issue a revised map...

R.W.S has decided to issue a Winter Weather Advisory as of 2:30 AM effective the next 6-9 hours. This will apply to the counties of berks and lehigh in PA.
WAA snows have overspread the area and continue to move thru in the next 6-9 hours.
The culprit for this is a clipper vortex south of the Great Lakes region which is slowly moving to the East Northeast. This vortex will spin out other vortexes and keep the chance of light snow thru out the day today and possibly into monday morning.
With the extremely cold temperatures that have been in place the snow will quickly make roads difficult to travel.
Over all R.W.S is not expecting much more then 1-3 inches in Lehigh and Berks County.
Spotter reports indicate that around an inch of snow has fallen in the ABE area.
Stay tuned to later statements if they become necessary! Bundle up when heading outside overnight tonight.

A Winter Weather advisory means that light snow /sleet/Zr is occurring and expected till the advisory expires. This advisory is expected to expire by 10 AM Est January 18th 2009

Clipper Snow Fall Totals For Jan 17-18 2009

A little clarification on the map above. The Philadelphia area and SJ area may see some light snow or flurries but would fall under the category of a nuisance type situation so thats why it is not included on the map.
Regardless of whether or not you get snow from this clipper..Make sure to bundle up as it will not be getting out of the teens over the majority of the area..

Omega Block Preliminary Map for Jan 17th Clipper

Pretty much in agreement between the two of us at this stage and time for the clipper..

January 17-18th Clipper and Coastal Scenarios

Ok these are scenario only maps and not a forecast. However..I think they are the most likely scenario at the moment. Going with a blend of the GFS/GGEM/UKMET and ECM involved to some extent as it is nodding towards the GFS....

Again these are scenario maps and not an actual forecast


What I am expecting to happen is for the Vortmax currently in Canada to drop South and break off a piece of energy and head it SE thru the ohio Valley and form a secondary off the coast of southern NJ. Which will move NE ward up the coast.
Meanwhile as this is happening that same vortmax will drop down the outside of the trough and swing into the SE states tapping into GOM moisture and will round the base of the trough and head NE up the eastern seaboard...With cold arctic air in place i do not see temperatures being an issue for anywhere with the exception of extreme southern New England coastline ..If we get a track to the benchmark then they as well will be mainly snow....

3:10 AM Update

R.W.S has effectively canceled the WWA that was in effect for all counties in PA & NJ....

Clipper currently located to the south of central Pa will continue to move ESE to off the southern Jersey coast. However...due to the very cold air most precipitation is falling aloft and not making it across the mountains in central Pa.
For the rest of the overnight expect clouds and windy conditions developing and dropping temperatures. As far as precipitation nothing more then flurries or a squall with the passage of the arctic front that may whiten the ground..

Updated at 12:30 AM

I placed this update on accuweather forums as soon as i got home from work....

Cloudy skies here ..I am downgrading the Map I had .....

Reason being is that the mountains have really broken up the moisture and ...the amount of virga and the moisture appears to be splitting into two sections...One heading NE and one heading ESE

As you can see the clipper is located to the south of SW PA ...
So with the above info and being stuck at work 8-12 midnight...this is the first time I have had a chance to revise my map and my thinking...
Although earlier this evening i sensed this heading SE..

The white section is 1-3 inches! Sorry forgot the color code for it!

Omega Block Final Map for January 14,15th

White Plains, NY (Jan. 14th. '09 - 1:22 AM):

Clipper moving from the Ohio valley to the east coast, will affect the area, by ejecting off the east coast via southern NJ-northern Delmarva during the late night hours of Wednesday the 14th, into the late morning hours of Thursday the 15th.

Moisture (QPF) associated with the clipper, ranges from 0.10 to 0.25, which due to high snow ratios as a result of very cold temperatures in the upper to lower 10's, will result in as much as 6 inches of snow from NE PA to N NJ on to NYC metro, SE NY and Long Island and then into RI, SE Mass and the Cape Code area. Areas to the north and south of the heavier axis of snow, will, possibly, pick up as much as 3 inches of snow.

Blustery conditions will exist, which could lead to the possibility of blizzard-like conditions. Winds could gust as high as 35 MPH and be sustained from 15 to 25 MPH during Thursday. As a result, dangerously cold windchill possibly below 1F and blowing snow may likely cause very problematic conditions for drivers and pedestrians. Make sure to bundle up in layers to be prepared for the harsh conditions that this weather event will bring.

Omega Block Weather will likely issue a Winter Weather Advisory for the forecast area, for as much as 6 inches of snow, any time between the next few hours and Wednesday afternoon. Please stay tuned for further updates.