FPCN39 CWLW 211432
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 21 August 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      31   23     850   4    100   28    3200   7
KAMLOOPS     KEL      57   24    1500   5    100   29    3350   7
OKANAGAN     KEL      36   22    1000   5    100   28    3350   7
CASTLEGAR    SPOK     46   22    1300   6    100   27    3500  17
CRANBROOK    SPOK     40   22    3950   8    100   25    3950  18
REVELSTOKE   KEL      11   19     600   1     53   23    1500   5

*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   SW  13   SW  24
CRANBROOK             W   13   W   30

           INVERSION HT    BREAKTHRU TEMP
KELOWNA         650 m         21 C
SPOKANE        1740 m         23 C

TODAY'S VENTING: BECOMING FAIR BY MID MORNING AND GOOD NEAR NOON.

VENTING FOR FRIDAY: GOOD

VENTING OUTLOOK SATURDAY THRU MONDAY:GOOD IN THE AFTERNOONS
AS A MODERATE TO STRONG SOUTHWESTERLY FLOW LIES ACROSS
THE REGION. EMBEDDED IN THIS FLOW WEAK TROUGHS CROSS THE REGION
AND KEEP VENTING 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.      9   20     950   5    100   24    3950  11
PR. GEORGE   P.G.      9   19     700   6     48   23    1450   6
SMITHERS     P.G.     15   19     650   4     25   23     850   5
WELLS GRAY   P.G.      9   20    1000   5    100   25    4000  11
FT NLSN      P.G.      9   17     400   4     28   23     800   5
FT STJOHN    P.G.      9   15     700   6     17   21     850   6

*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   35   W   43
SMITHERS              W   17   NW  43

           INVERSION HT    BREAKTHRU TEMP
PR. GEORGE       860 m         21 C
FT. NELSON       900 m         21 C

TODAY'S VENTING: BECOMING FAIR TO GOOD IN THE CENTRAL INTERIOR
HOWEVER NORTHERN SECTIONS WILL REMAIN ONLY FAIR TO POOR AS CLOUDS
KEEP TEMPERATURES FROM BREAKING THROUGH THE INVERSION.

VENTING FOR FRIDAY: GOOD

VENTING OUTLOOK SATURDAY THRU MONDAY: FAIR TO GOOD AS A NUMBER
OF WEAK TROUGHS CROSS THE REGION.

COAST

           UPPER      ***** MORNING ******    ***** AFTERNOON ****
             AIR      VI  Tmp  MXG HT  Wnd    VI  Tmp  MXG HT  Wnd
                               (mASL)  (kt)            (mASL)  (kt)
VANCOUVER    QUIL     41   19     950   5     80   22    2050   8
FRASER VLY   QUIL     48   19     900   5     80   23    2050   8
SRN VRISL    QUIL     41   17     400   5     80   21    1400   8
CNTRL VRISL  QUIL     60   19     850   3     80   22    1450   8
NRN VRISL    HRDY     25   16     400   5     68   19     850  10
TERRACE      ANT      45   19     500  15     57   23     750  11
STEWART      ANT      54   18     400  14     67   23     600  14

*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    S    9   S   15   SW  30
PORT HARDY   S   17   S   26   S   28
SANDSPIT     SW  19   VR   5   VR   5

           INVERSION HT    BREAKTHRU TEMP
QUILLAYUTE      NONE           NONE
PORT HARDY      1500 m         20 C
ANNETTE          800 m         24 C

TODAY'S VENTING: FAIR BECOMING GOOD ON THE CENTRAL COAST.
ELSEWHERE BECOMING GOOD BY NOON.

VENTING FOR FRIDAY: GOOD

VENTING OUTLOOK SATURDAY THRU MONDAY:FAIR TO GOOD AS A NUMBER
OF WEAK TROUGHS CROSS THE REGION.

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

END/LM