Sunday, December 5, 2010

Forecast for Western/Northwestern WI.

Forecast problems… Temps are going to be tricky...LES…Then our next weather maker for Thursday/Thursday night… Then more Arctic air on the way after that…


At the 6 AM we find a rather large range in temps….Where skies are clear temps have dropped to 2° to 5°…Where skies are cloudy temps are range from 11° to 16°…. Temps still could fall off a few more degrees as we head towards sunrise… There has been some light snow/flurries reported across the area…. Winds are from the West/Northwest from 3 to 10 MPH….This is causing wind chills to fall from 2°+ to -8°….


Looking at the SFC charts this morning we find a rather large 1036 MB high pressure centered over Southeastern SD per RCU, while GFS/NAM have the center a little more North or West..Looking at the 500 MB charts upper level low pressure is centered just North of NY. Meanwhile we find a building ridge in the Western states…. Both these features will insure us of a Northwesterly flow.. We also find a upper level low/trough out over the Pacific ocean…
What this means our weather shall remain cold through midweek…With off and on clouds from weak shortwaves dropping South/Southeast in the Northwesterly flow…. Back down at the SFC charts… Looking at the GFS model we see things really don’t change in the weather pattern through Tuesday night, Wednesday high pressure is forecasted to move of the area this will allow for WAA to slowly kick back in as we get a return flow from the South/Southwest this will allow for temps to warm back into the middle to upper teens…Meantime a piece of energy breaks off from the upper level low off the Western Canada Coast.. This move into Southern Alberta Canada then down into Northwest ND by late Wednesday night/early Thursday morning.. This low is forecasted to move into Southwestern MN early Thursday morning and weaken to around 1000 MBS…By late Thursday night/early Friday morning the low is forecasted to be centered in Western MI… Still looks to bring accumulating snows back into the FA… Track of this system is more North than the last one we just done dealing with, so if this works out the heavier snow bands will be setting up more North…. ECMWF model agrees on the track, however its much weaker with the system…. Both models do agree on another Arctic blast along with strong Northwest/North winds behind this system…..
LES will still be a problem through my LES belts as cold Northwest/North wind flow over the warm waters of Lake Superior… This may be ongoing thing through Tuesday night before the SFC winds become more westerly.
In fact the light snow/flurries we are seeing this morning and throughout the rest of the day, is thanks to Lake Superior…..
So for today through Wednesday looks for off and on clouds with flurries today……Temps could have a wide range to them… Places that see more clear skies will be colder than other places seeing cloudy skies…. So will run like this
Highs from today through Tuesday 13 to 16 with lows from -10 to plus 3…..That should cover it rather good…Wednesday and Thursday temps warm into the upper teens to lower 20s…Lows in the upper single digits to the lower teens….. Snow is looking like a good bet for Thursday/Thursday night…. Will issue a snowfall map on Tuesday or Tuesday night if needed…. Arctic air slams back into the area for next weekend into the following work week… More on that later… However that looks to be our coldest air yet of the this winter…..