Terms and Abbreviations used in the Forecast Text

• Alberta Clipper - An area of low pressure that originates from the Canadian Prairie Province of Alberta.  The low usually tracks MN, WI and into far northern sections of IL, IN, OH and southern lower MI.  Light snows on the order of 1-4" usually fall with these systems.  There is usually arctic air in place when the storm arrives and thus the snows are usually light and fluffy.
• Canadian High - Area of high pressure that moves in from Canada.  These generally produce clear weather and cold temps.
• Cat (x) Storm - A snow storm where (x) is used to describe the intensity level (1-6) using the Dee Snowstorm Scale.
• Clipper low - see Alberta Clipper
• Colorado low - An area of low pressure that forms on the east side of the Rockies in the vicinity of eastern CO and then tracks almost due east through the central Plains and central/northern Midwest.  These low pressures generally bring light to moderate snows on the order of 3-8" to the northern 1/2 of the Midwest.
• Cross Polar Flow - The atmospheric setup when the jetstream crosses the north pole and continues nearly straight south into the US.  This setup generally produces the coldest air outbreak possible for the central US.
• Cut off Low - An area of low pressure in the upper atmosphere that is cut off from the main jetstream flow.  Cut off lows can be very slow to move and thus produce a prolonged precipitation event over the area where it is sitting.
• Ensemble - Long term forecast model, going out to 360 hours with global coverage.  The Ensemble is actually just what it says it is, an ensemble of different runs of the GFS.  Each version of the GFS has been tweaked to "force" an error into the forecast.  They then take the averages of all these models to try and hone in on the strong points of the forecast and eliminate as many errors as possible.
• ETA - Short term forecast model, going out to 84 hours covering North America Only
• GFS - Long term forecast model, going out to 360 hours with global coverage
• Jetstream - A corridor of stronger winds in the higher levels of the atmosphere- typically 20-30 thousand feet above the surface of the earth.  There can be as many as three different jetsream branches going over the US at any particular time.  The sub tropical jet rides along the southern US and separates the cool air of the mid latitudes from the warmer and more humid air of the tropics or sub tropics.  The polar jet is the main weather making jet in the US and separates the cool air of the mid latitudes from the cold air of the higher latitude regions.  The arctic jet occasionally visits the lower 48 in the cold months.  It separates the cold air of the higher latitudes from the bitterly cold air of the arctic.
• LES - Lake Effect Snow
• LES Belts - The areas downwind of the Great Lakes that are favored for Lake Effect snow.  (see map)
• Low Level Jet - A corridor of stronger winds in the lower levels of the atmosphere (1000-7000 feet above the earths surface). 
• Midwest - The states including the Dakotas, MN, IA, WI, IL, MI, IN and OH.
• Northwest Flow - The atmospheric setup when the jetstream is aligned from western Canada into the central and southeast US.  Known to bring below average temperatures to the Midwest along with below average precipitation.
• Northwoods - Opinions my differ, but my description of the Northwoods of the Midwest is areas generally to the north of a line from about Fargo ND to Brainerd MN to Wausau WI to Houghton Lake MI.
• NWL - Northwest lower MI.  Area of MI running roughly from about Frankfort to Grayling to Cheboygan
• OH River Valley - Area of land around 100 miles either side of the OH River from it's juncture with the MS River to the south eastern corner of OH
• Panhandle Hooker - An area of low pressure that forms in the vicinity of the TX/OK panhandle region.  It then tracks to the east and northeast into the Midwest.  These storms are known to bring heavy snows to the Midwest on their northwest side of the low.
• Phasing or Jet Stream Phasing - A situation when the troughs of one or more of the jetstreams phase up or become aligned.  This usually results in the combining of the energies contained in the different jetstreams and forms a powerful area of low pressure.
• Split Flow - Nearly the opposite of phasing.  It is when the different branches of the jetstream are misaligned or separated from each other.  This setup usually causes the polar jet to be displaced to the north and puts the northern US in above average temps.  Storms can still form, but are usually not big snow producers because of the mild temps.
• SWL - Southwest Lower MI.  An area of MI running from the IN border north to near Holland.