SUBROUTINE WINDG(KFILDO,P,NX,NY,
     1                 MGUESS,IPREX2,PREX3,PREX4,PREX5,ISTOP,IER)
C
C        DECEMBER  2011   GLAHN   MDL   MOS-2000
C        JANUARY   2012   GLAHN   DIFFERENT FORMULA
C
C        PURPOSE
C            TO ENHANCE A WIND SPEED GRID BY A FACTOR WHEN THE
C            SPEED IS GE 20 KTS.  THE FACTOR IS AN EQUATION BY
C            TATTLEMAN (J. APP. METEOR, 1975, VOL. 14, PP. 1271-1276)
C            AND USED IN THE COMPUTER WORDED FORECAST
C            (GLAHN; 1978, TDL TECH MEMO NWS TDL-67)
C
C            GUST = SPEED*(1. + PREX4 * EXP(PREX5 * SPEED)) 
C
C        DATA SET USE
C            KFILDO   - UNIT NUMBER FOR OUTPUT (PRINT) FILE.  (OUTPUT)
C
C        VARIABLES
C              KFILDO = UNIT NUMBER FOR OUTPUT (PRINT) FILE.  (INPUT)
C            P(IX,JY) = HOLDS A WIND FIELD TO BE ENHANCED
C                       (IX=1,NX) (JY=1,NY), WHERE NX AND NY ARE THE
C                       SIZE OF THE GRID.  (INPUT/OUTPUT)
C                  NX = SIZE OF P( , ) IN X DIRECTION.  (INPUT)
C                  NY = SIZE OF P( , ) IN Y DIRECTION.  (INPUT)
C              MGUESS = THE NUMBER OF THE FIRST GUESS PROVIDED.
C                       MGUESS = 2 MEANS A MODEL FIRST GUESS THAT
C                       NEEDS TO BE ENHANCED.  (INPUT)
C              IPREX2 = THE NUMBER OF THE FIRST GUESS THAT WILL BE
C                       TRANSFORMED.  (INPUT)
C               PREX3 = THE THRESHOLD ABOVE WHICH THE WIND IS TO
C                       BE INCREASED.  (INPUT)
C               PREX4 = A CONSTANT, ALONG WITH PREX5, THAT IS IN THE
C                       AUGMENTATION EQUATION.  (INPUT)
C               PREX5 = SEE PREX4. (INPUT)
C               ISTOP = INCREMENTED BY 1 IF THERE IS AN ERROR.
C                       (INPUT/OUTPUT)
C                 IER = RETURN CODE.
C                         0 = GOOD RETURN.
C                       (OUTPUT)
C        1         2         3         4         5         6         7 X
C
      DIMENSION P(NX,NY)
C
      IER=0
C
D     WRITE(KFILDO,103)NX,NY,MGUESS,IPREX2,PREX3,PREX4
D103  FORMAT(/' IN WINDG--NX,NY,MGUESS,IPREX2,PREX3,PREX4',
D    1        4I8,2F6.2)
C   
      IF(MGUESS.NE.IPREX2)GO TO 300  
C
C        ENHANCE THE POINTS.
C
      DO 200 JY=1,NY
      DO 199 IX=1,NX
C
      IF(P(IX,JY).LT.9998.9)THEN
C           THIS IS A NON MISSING POINT.
C
         IF(P(IX,JY).GE.PREX3)THEN
             P(IX,JY)=P(IX,JY)*(1.+PREX4*EXP(PREX5*P(IX,JY)))
         ENDIF
C
      ENDIF
C
 199  CONTINUE
 200  CONTINUE
C
 300  RETURN
      END