FPCN39 CWLW 311433
SMOKE CONTROL FORECAST FOR COASTAL BC AND THE INTERIOR INCLUDING THE
NORTHEAST ISSUED BY THE MOUNTAIN WEATHER SERVICE OFFICE OF
ENVIRONMENT CANADA AT 8:00 AM PDT Thursday 31 July 1997 FOR TODAY.

VENTILATION INDICES (TEMPERATURE) AND MIXING HEIGHTS.
MIXING HEIGHTS IN METRES ABOVE SEA LEVEL.
AVERAGE WINDS IN KNOTS.

SPOT INDICES ARE DETERMINED BY THE ASPECT AND ELEVATION OF THE SITES.
COMPARE WINDS, TEMPERATURES AND ELEVATION WITH THE SITES HERE
TO DETERMINE THE INDEX IN ANY OTHER AREA.

SOUTHERN INTERIOR

           UPPER      ***** MORNING ******    ***** AFTERNOON ****
             AIR      VI  Tmp  MXG HT  Wnd    VI  Tmp  MXG HT  Wnd
                               (mASL)  (kt)            (mASL)  (kt)
FRSR CANYN   KEL      19   21     650   2     71   28    2400   4
KAMLOOPS     KEL      15   19     650   2    100   28    3350   7
OKANAGAN     KEL      15   19     650   2     84   27    2500   6
CASTLEGAR    SPOK     24   20     800   5     69   27    2000   6
CRANBROOK    SPOK      9   18     950   6    100   25    3950   9
REVELSTOKE   KEL      12   17     600   2     28   22    1350   2

*SUBTRACT 20 FROM THE VENTILATION INDEX IN VALLEYS IF THE MIXING
HEIGHT IS BELOW THE HEIGHT OF THE LOCAL HILLS.

FORECAST UPPER WINDS FOR THURSDAY AFTERNOON (WINDS IN KM/H):
             900m     1800m    2700m
PENTICTON    VR   5   S   13   SW  20
CRANBROOK             SW   9   SW  22

           INVERSION HT    BREAKTHRU TEMP
KELOWNA          700 m         19 C
SPOKANE         1000 m         21 C

TODAY'S VENTING: generally good.

VENTING FOR FRIDAY: generally good.

VENTING OUTLOOK SATURDAY THRU MONDAY: generally good.


CENTRAL INTERIOR/NORTHEAST

           UPPER      ***** MORNING ******    ***** AFTERNOON ****
             AIR      VI  Tmp  MXG HT  Wnd    VI  Tmp  MXG HT  Wnd
                               (mASL)  (kt)            (mASL)  (kt)
WILLIAMS L   P.G.    100   17    2550  15    100   25    3950  15
PR. GEORGE   P.G.     88   17    1600  15    100   24    3700  14
SMITHERS     P.G.      9   14     500   4    100   22    3500  13
WELLS GRAY   P.G.    100   18    4000  15    100   25    4000  15
FT NLSN      F.N.     65   15     850  16     90   18    1250  16
FT STJOHN    F.N.     85   16    1450  16    100   22    2850  15

*SUBTRACT 20 FROM THE VENTILATION INDEX IN VALLEYS IF THE MIXING
HEIGHT IS BELOW THE HEIGHT OF THE LOCAL HILLS.

FORECAST UPPER WINDS FOR THURSDAY AFTERNOON (WINDS IN KM/H):
             900m     1800m    2700m
PR. GEORGE            W   11   SW  24
SMITHERS              SW  17   SW  24

           INVERSION HT    BREAKTHRU TEMP
PR. GEORGE      none
FT. NELSON      none

TODAY'S VENTING: good.

VENTING FOR FRIDAY: good.

VENTING OUTLOOK SATURDAY THRU MONDAY: good.


COAST

           UPPER      ***** MORNING ******    ***** AFTERNOON ****
             AIR      VI  Tmp  MXG HT  Wnd    VI  Tmp  MXG HT  Wnd
                               (mASL)  (kt)            (mASL)  (kt)
VANCOUVER    QUIL     50   17     750   7     79   22    1850   6
FRASER VLY   QUIL     44   16     600   7     81   23    1900   6
SRN VRISL    QUIL     39   16     550   6     74   22    1800   5
CNTRL VRISL  QUIL     49   18     800   6     74   22    1800   5
NRN VRISL    HRDY     49   14     800   6     74   18    1800   5
TERRACE      ANT     100   16    1350  19    100   20    2700  17
STEWART      ANT      62   15     450  15    100   20    2050  17

*SUBTRACT 20 FROM THE VENTILATION INDEX IN VALLEYS IF THE MIXING
HEIGHT IS BELOW THE HEIGHT OF THE LOCAL HILLS.

FORECAST UPPER WINDS FOR THURSDAY AFTERNOON (WINDS IN KM/H):
             900m     1800m    2700m
VANCOUVER    W   11   SW  13   SW  24
PORT HARDY   VR   5   SW   9   SW  13
SANDSPIT     SW  24   SW  24   SW  24

           INVERSION HT    BREAKTHRU TEMP
QUILLAYUTE       200 m         14 C
PORT HARDY       100 m         15 C
ANNETTE          none

TODAY'S VENTING: good.

VENTING FOR FRIDAY: good.

VENTING OUTLOOK SATURDAY THRU MONDAY: good.


VENTILATION GUIDELINES:
          0-33.....POOR
          34-54.....FAIR
          55-100.....GOOD.
VENTILATION INDICES NORMALLY DROP TO POOR AFTER SUNSET.

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