Chapter 12 cover

Homework/Reading: Review 201 Precipitation Processes (or advanced – Ch 6 of W&H)Lyndon State Online Notes: http://apollo.lsc.vsc.edu/classes/met130/notes/chapter7/index.html

A Supercool Discussion:

Pure Water hard to FreezeLiquid to LatticeIf warmer than about -40 (C or F, doesn’t matter), need Ice Nuclei Colder than -15 C + IN = Good to Go-15 to -5 may freeze, otherwise, staying supercool(ed) UNTIL

Hits something below freezing, (or encounters a snowflake or other frozen hydrometeor)

Figure 12.1

N-G’s Snow/Freezing Precip. Forecasting Method (203)

• http://www.met.tamu.edu/class/wflm/tut/snow/snow5.html

• Our HDWX Chart based on it. – http://hdwx.tamu.edu/product.php?

productID=223

Figure 12.2

The “warm rain” process for freezing drizzle.

Figure 12.3

FRZL may be minor to the ground – but disastrous for aircraft.

Figure 12.4

Where did this low come from?

Figure 12.5

Figure 12.6

Deep South rare, but devastating!

Figure 12.7

Figure 12A

-Southern Ice Storm of Feb 1994 (MS, LA, AR, AL, TN, Extreme NE Texas

26 Counties in MS had Federal Disaster Declaration

Synthetic CLL Sounding from recent near Freezing Rain Event

Figure 12B

January 1998 Northeast Ice Storm

Figure 12C

1998!