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20011024: 20011024: GEMPAK Wind Chill again



Daryl,

I have packaged up the GEMPAK 5.6.e tar file on the ftp server.
This includes the WCHT addition. Our web guy says he'll add the link to
the web download site soon.

There will be a 5.6.e.1 release next week, so I am not going to make
a general release including all the release notes until then.

Steve Chiswell

>From: Unidata Support <address@hidden>
>Organization: UCAR/Unidata

>>From: Daryl Herzmann <address@hidden>
>>Organization: UCAR/Unidata
>>Keywords: 200110242213.f9OMDV122314
>
>>Hi,
>>      In regards to:
>>http://www.unidata.ucar.edu/glimpse/gempak/4634
>>http://www.unidata.ucar.edu/glimpse/gempak/4607
>>
>>      The NWS is using a different formulation then the one in GEMPAK
>>for wceq.  I got an email today from the NWS about a Wind Chill plot I
>>have.  They are concerned with the discrepancy between my plot on the web
>>and what they will be issuing.  Is this an issue with NCEP, or not knowing
>>what the new formula is?  I am not sure myself.  I can try to find it if
>>you wish.  My abilities are lacking to create my own formulation and then
>>patch GEMPAK with it, so I am seeking divine help.  If I provided the
>>formula, could you create a patch to use it in GEMPAK?
>>
>>Thanks,
>>      Daryl
>>
>>-- 
>>/**
>> * Daryl Herzmann (address@hidden)
>> * Program Assistant -- Iowa Environmental Mesonet
>> * http://mesonet.agron.iastate.edu
>> */
>>
>
>Daryl,
>
>The next release of GEMPAK (5.6.E) has a new SFPARM called
>WCHT: Revised wind chill temperature in Fahrenheit
>computed using the following formula: 
>
>        FUNCTION PR_WCHT ( tmpf, sknt )
>C************************************************************************
>C* PR_WCHT                                                              *
>C*                                                                      *
>C* This function computes WCHT, the wind chill temperature from TMPF    *
>C* and SKNT.  The input values will first be converted to miles per     *
>C* hour.  The output will be calculated in Fahrenheit.                  *
>C*                                                                      *
>C* WCHT is the temperature with calm winds that produces the same       *
>C* cooling effect as the given temperature with the given wind speed.   *
>C*                                                                      *
>C* The following equation is used:                                      *
>C*                                                                      *
>C*      PR_WCHT = 35.74 + ( .6215 * TMPF ) - 35.75 * WCI ( V ) +        *
>C*                0.4274 * TMPF * WCI ( V )                             *
>C*                                                                      *
>C*              where:  WCI ( V ) = ( V ** 0.16 )                       *
>C*                      V: Wind Speed (mph)                             *
>C*                                                                      *
>C* REAL PR_WCHT ( TMPF, SKNT )                                          *
>C*                                                                      *
>C* Input parameters:                                                    *
>C*      TMPF            REAL            Air temperature in deg F        *
>C*      SKNT            REAL            Wind speed in knots             *
>C*                                                                      *
>C* Output parameters:                                                   *
>C*      PR_WCHT         REAL            Wind Chill temperature in deg F *
>C**                                                                     *
>C* Log:                                                                 *
>C* T. Lee/SAIC           9/01                                           *
>C* T. Lee/SAIC           9/01   Set windchill <= air temp               *
>C************************************************************************
>
>
>I will be making a release of this distribution soon.
>
>Steve Chiswell
>