FPCN39 CWLW 251338
SMOKE CONTROL FORECAST FOR COASTAL BC AND THE INTERIOR INCLUDING THE
NORTHEAST ISSUED BY THE MOUNTAIN WEATHER SERVICE OFFICE OF
ENVIRONMENT CANADA AT 7:00 AM PDT THURSDAY 25 SEPTEMBER 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      13   18     550   1     31   26    1000   3
KAMLOOPS     KEL      12   18     600   1     26   24    1000   3
OKANAGAN     KEL      11   17     550   1     29   26    1150   3
CASTLEGAR    SPOK     21   16     800   4     29   24    1000   4
CRANBROOK    SPOK      9   15     950   9      9   24     950   9
REVELSTOKE   KEL       9   13     500   1     13   18     650   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    S   11   S   26   S   48
CRANBROOK             VR   5   W   20

           INVERSION HT    BREAKTHRU TEMP
KELOWNA         1100 m         26 C
SPOKANE         1300 m         28 C

TODAY'S VENTING: poor.

VENTING FOR FRIDAY: poor.

VENTING OUTLOOK SATURDAY THRU MONDAY: poor.


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   17     950  25     10   20     950  25
PR. GEORGE   P.G.     11   13     700  15     29   18     850  15
SMITHERS     P.G.     16   12     650   5     27   18     750   8
WELLS GRAY   P.G.      9   12    1000  25     51   20    1200  25
FT NLSN      F.N.      9   12     400  12     42   22     700  12
FT STJOHN    F.N.      9   15     700  12     49   22     700  12

*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            S   41   SW  59
SMITHERS              S   37   SW  59

           INVERSION HT    BREAKTHRU TEMP
PR. GEORGE      1200 m         26 C
FT. NELSON       800 m         24 C

TODAY'S VENTING: poor to fair.

VENTING FOR FRIDAY: poor to fair.

VENTING OUTLOOK SATURDAY THRU MONDAY: becoming good by Saturday
then decreasing to poor.


COAST

           UPPER      ***** MORNING ******    ***** AFTERNOON ****
             AIR      VI  Tmp  MXG HT  Wnd    VI  Tmp  MXG HT  Wnd
                               (mASL)  (kt)            (mASL)  (kt)
VANCOUVER    QUIL     54   18     500  13     96   21     900  19
FRASER VLY   QUIL     85   20     800  17    100   24    1000  19
SRN VRISL    QUIL      9   16       0   7     78   20     750  14
CNTRL VRISL  QUIL      9   16      50   7     78   20     750  14
NRN VRISL    HRDY      9   17       0  25     38   18     150  25
TERRACE      ANT       9   13     200  32    100   18     800  32
STEWART      ANT     100   17     350  55    100   18     400  55

*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   24   S   50   S   70
PORT HARDY   S   44   S   57   S   67
SANDSPIT     S   41   S   48   S   56

           INVERSION HT    BREAKTHRU TEMP
QUILLAYUTE       100 m         18 C
PORT HARDY       900 m         25 C
ANNETTE          400 m         18 C

TODAY'S VENTING: good coast poor inland.

VENTING FOR FRIDAY: good.

VENTING OUTLOOK SATURDAY THRU MONDAY: decreasing to fair.

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


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