NTIM I sent today

• To: l.miller.ucar(rec)
• Subject: NTIM I sent today
• From: C.ALEX
• Date: Fri, 7 Jan 1994 10:12:04 -0700

Posted: Tue, Jan  4, 1994   3:59 PM EST              Msg: EGJE-6037-5927
Subj:   NTIM I sent today                             

WSHPNSNMC
NOUS41 KWBC 042039

NATIONAL TECHNICAL INFORMATION MESSAGE 94-01
NATIONAL WEATHER SERVICE HEADQUARTERS
330 PM EST TUE JAN 4 1994

TO:         ALL NWS OFFICES, DOMESTIC DATA SERVICE SUBSCRIBERS,
            FAA USERS, AND OTHER USERS OF NGM MOS GUIDANCE

FROM:       JOHN F. MACHOWSKI
            ACTING CHIEF, SERVICES DEVELOPMENT BRANCH

SUBJECT:    CHANGES TO NGM MOS PRECIPITATION TYPE EQUATIONS AT
            THE 6- AND 9-H PROJECTIONS

(THE FOLLOWING INFORMATION WAS PROVIDED BY MARY ERICKSON OF THE
TECHNIQUES DEVELOPMENT LABORATORY)

On January 5, 1993, the NGM MOS equations used to forecast
precipitation type at the 6- and 9-h projections will be changed. 
The new equations contain additional observed predictors which
improve the skill of the forecasts.  The new predictors
include the observed dew point depression, the average of the
observed temperature and dew point, and three binary observed
precipitation type predictors.  The binary observations are
snow/no snow, rain/no rain, and freezing precipitation (ZP)/
no ZP.  The appropriate binary predictor is turned on (takes
on a value of 1) when the precipitation type occurs, and is off
(the value is 0) otherwise.  Of the five new observed predictors,
the ZP/no ZP and snow/no snow were most often included in the
equations.

The precipitation type guidance is available in the NGM MOS
matrix, which is available on AFOS under the category FWC and to
other users under WMO header FOUS14 KWBC.  

If you have any questions about this change, call Mary Erickson
or John Jensenius at (301)-763-8151. 

END