Heavy Rainfall Across the Southwest, Mid-Atlantic and Florida; Fire Weather Concerns in the Northwest and Alaska

Heavy to excessive rainfall may bring flooding to parts of Arizona, New Mexico, Florida, North Carolina, and Virginia today. Recently burned areas will be particularly vulnerable to flash flooding. Gusty winds and low humidity will bring elevated to critical fire weather conditions to parts of the Northwest U.S. and central Alaska today. Read More >

ZBW Aviation Weather SA--Winter Mesoanalysis

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Moisture/Lift/Instability

850 mb Frontogenesis 800-750 mb EPV	700 mb Frontogenesis 650-500 mb EPV	Mid Level Lapse Rates	850 mb Moisture Transport

Snow Squall Parameter	Deep Moisture Convergence	Jet Circulation	700-400 mb Vorticity Advection

Snow Squall Parameter: A non-dimensional composite parameter that combines 0-2 km AGL relative humidity, 0-2 km AGL potential instability (theta-e decreases with height), and 0-2 km AGL mean wind speed (m/s). The intent of the parameter is to identify areas with low-level potential instability, sufficient moisture, and strong winds to support snow squall development. Surface potential temperatures (theta) and MSL pressure are also plotted to identify strong baroclinic zones which often provide the focused low-level ascent in cases of narrow snow bands.

The index is formulated as follows:Snow Squall = ((0-2km mean RH - 60%) / 15%) * (( 4 - 2km_delta_theta-e) / 4) * (0-2km mean wind / 9 m s^-1)

The 2km_delta_theta-e term is the change in theta-e (K) from the surface to 2km AGL, where negative values represent potential instability. Areas with 0-2 km RH < 60% are filtered out in the color fill plots.

Thermodynamics

SFC Wet Bulb	925 mb	850 mb	Top-Down P-Type

Heavy Rainfall Across the Southwest, Mid-Atlantic and Florida; Fire Weather Concerns in the Northwest and Alaska

Boston CWSU Situational Awareness