RUC Cloud/Ceiling Forecasts with and without TAMDAR. Brian Jamison NOAA/FRD/FSL - CIRA. August 18, 00 UTC, 6hr fcst. Dev forecast - shows low ceilings just north of MN, also some low ceilings in southern IL and IN. August 18, 00 UTC, 6hr fcst.
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NOAA/FRD/FSL - CIRA
Dev forecast - shows low ceilings just north of MN, also some low ceilings in southern IL and IN.
Dev2 forecast - shows low ceilings in northern MN, fewer low ceilings in southern IL and IN.
Dev analysis - low ceilings in northern MN verify for Dev2, but Dev forecast is somewhat better for ceilings in southern IL and IN.
Dev forecast of Aviation Flight Rules - similar to ceiling forecast
Dev2 forecast of Aviation Flight Rules - similar to ceiling forecast. Shows large area of LIFR over northern MN.
Analysis of Aviation Flight Rules - most of the area of LIFR over northern MN verifies for Dev2.
Dev forecast - shows MI cloud free over almost the entire state.
Dev2 forecast - some bases between 3000-5000 ft. in central MI.
Verifying analysis has ceilings over most of MI, favoring the Dev2 forecast.
Observed ceilings from METAR network further validate low ceilings over MI.
TAMDAR data that likely contributed to the Dev2 fcst. Three separate soundings show a high RH layer at about 5000 ft.
Dev forecast - a few areas of low ceilings in Great Lakes area including a small area in southeast WI.
Dev2 forecast - more low ceilings in the Great Lakes area, particularly over Lake Superior and Lake Michigan. Low ceilings in SE WI extend further north.
Verifying analysis shows some low ceilings over Lake Superior and in central and SE WI.
METAR ceiling observations identify the ceilings in WI, a few in MI, and one just south of Lake Michigan, but no METAR sites on the Lakes themselves.
Visible satellite image confirms clouds in WI and MI, but none over the Great Lakes. Why did Dev2 show extensive low ceilings?
Four TAMDAR flights near Lake Superior.
Corresponding TAMDAR soundings near Lake Superior. Note the northerly winds.
Difference plot for 1000mb reveals RH differences in and south of Lake Superior. Also note that temperature differences in the same area show Dev2 to be colder than Dev.