Bill Schintler
EF4
A prolonged period of light snow will bring a few inches of the white stuff to the Eastern Iowa area beginning shortly after midnight on Monday. Following are forecasts for specific areas in the area:
Cedar Rapids:
Light snowfall will start at 1 AM Monday, and continue through 2 AM Tuesday. Total accumulation: 5.1 inches.
Iowa City:
Light snowfall will start at 1 AM Monday, and continue through 2 AM Tuesday. Total accumulation: 3.4 inches.
Marengo:
Light snowfall will start at 1 AM Monday, and continue through 2 AM Tuesday. Total accumulation: 3.8 inches.
Paris/Coggon (northern Linn Co.):
Light snowfall will start at 12:30 AM Monday, and continue through 2 AM Tuesday. Total accumulation: 5.5 inches.
Synopsis:
A stacked ULVL system was rotating over the Hudson Bay area and NRN Great lakes. Upstream from the trough was a sharp H7-H6 baroclinic zone extending from NWRN ND into ERN IA. Large scale assent in association with a couple of lead waves over the Dakotas showed up well on the WV loop. Closer to home, a very cold air mass was in place, with SFC temperatures hovering around 0F along with NWRLY winds gusting in excess of 35 mph.
Discussion:
This is somewhat of a complicated FCST as there will be several regions and mechanisms of forcing that will occur in the Upper Midwest throughout the event. Precipitation, which will be associated with a zone of H8-H7 frontogenesis, will start in NWRN into ERN IA after 06Z Monday. Top-down saturation of the column should occur rapidly as a lead wave approaches the region. During the day Monday, overrunning and isentropic uplift along the 290K-300K SFCS really kicks in over MO, while lifting parcels to their LFC where MUCAPEs of 250J/kg is indicated. A range of winter WX along with elevated convection and thunderstorms with marginally SVR hail is in store for areas around I-70. Late in the day Monday, an approaching vort-max will result in a few hours of strong kinematic forcing in the Upper-Midwest. There remains some disagreement between the MDLs as to exactly where the strongest lift will be, and now the best guess is for a UVM bulls-eye to track through NERN IA through 00Z Tuesday. Regarding snowfall amounts, relatively high snow/water ratios are used with snow production temperatures between -10C and -20C. Early in the event a 20:1 ratio is used, and this is tapered to 15:1 towards the end of the snowfall period with weak WAA in the dendritic growth region.
- bill
2:15 PM, Sunday, 02/10/08
Cedar Rapids:
Light snowfall will start at 1 AM Monday, and continue through 2 AM Tuesday. Total accumulation: 5.1 inches.
Iowa City:
Light snowfall will start at 1 AM Monday, and continue through 2 AM Tuesday. Total accumulation: 3.4 inches.
Marengo:
Light snowfall will start at 1 AM Monday, and continue through 2 AM Tuesday. Total accumulation: 3.8 inches.
Paris/Coggon (northern Linn Co.):
Light snowfall will start at 12:30 AM Monday, and continue through 2 AM Tuesday. Total accumulation: 5.5 inches.
Synopsis:
A stacked ULVL system was rotating over the Hudson Bay area and NRN Great lakes. Upstream from the trough was a sharp H7-H6 baroclinic zone extending from NWRN ND into ERN IA. Large scale assent in association with a couple of lead waves over the Dakotas showed up well on the WV loop. Closer to home, a very cold air mass was in place, with SFC temperatures hovering around 0F along with NWRLY winds gusting in excess of 35 mph.
Discussion:
This is somewhat of a complicated FCST as there will be several regions and mechanisms of forcing that will occur in the Upper Midwest throughout the event. Precipitation, which will be associated with a zone of H8-H7 frontogenesis, will start in NWRN into ERN IA after 06Z Monday. Top-down saturation of the column should occur rapidly as a lead wave approaches the region. During the day Monday, overrunning and isentropic uplift along the 290K-300K SFCS really kicks in over MO, while lifting parcels to their LFC where MUCAPEs of 250J/kg is indicated. A range of winter WX along with elevated convection and thunderstorms with marginally SVR hail is in store for areas around I-70. Late in the day Monday, an approaching vort-max will result in a few hours of strong kinematic forcing in the Upper-Midwest. There remains some disagreement between the MDLs as to exactly where the strongest lift will be, and now the best guess is for a UVM bulls-eye to track through NERN IA through 00Z Tuesday. Regarding snowfall amounts, relatively high snow/water ratios are used with snow production temperatures between -10C and -20C. Early in the event a 20:1 ratio is used, and this is tapered to 15:1 towards the end of the snowfall period with weak WAA in the dendritic growth region.
- bill
2:15 PM, Sunday, 02/10/08
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