FPCN39 CWLW 251343
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 PST THURSDAY 25 DECEMBER 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       9    0     300   1     32    3     800   6
KAMLOOPS     KEL       9   -1     400   1     34    2     900   6
OKANAGAN     KEL      10    0     500   1     31    2     900   4
CASTLEGAR    SPOK     13    0     600   2     37    2     900   5
CRANBROOK    SPOK      9   -8     950   4     27   -4    1400   4
REVELSTOKE   KEL       9   -1     500   1     21    0     700   3

*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   W    9   NW  22
CRANBROOK             NW  11   NW  33

TODAY'S VENTING: POOR.

VENTING FOR FRIDAY: FAIR TO 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   -4     950   2     20   -1     950  10
PR. GEORGE   P.G.      9    0     700   7     28    1     850  10
SMITHERS     P.G.     11    0     700   1     19    1     750   6
WELLS GRAY   P.G.     17   -4    1000   8     26    0    1000  12
FT NLSN      F.N.      9    0     400  10     21    0     400  15
FT STJOHN    F.N.     22    5     700  14     70    6    1150  20

*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   50   W   61
SMITHERS              SW  74   SW  61

TODAY'S VENTING: POOR EXCEPT GOOD BC PEACE.

VENTING FOR FRIDAY: POOR EXCEPT GOOD BC PEACE.

COAST

           UPPER      ***** MORNING ******    ***** AFTERNOON ****
             AIR      VI  Tmp  MXG HT  Wnd    VI  Tmp  MXG HT  Wnd
                               (mASL)  (kt)            (mASL)  (kt)
VANCOUVER    QUIL      9    2     100   6     21    6     350   6
FRASER VLY   QUIL      9    2      50   6     21    6     250   6
SRN VRISL    QUIL      9    6     250   0     20    7     350   6
CNTRL VRISL  QUIL      9    4     200   0     20    4     200   5
NRN VRISL    HRDY      9    5     100   7     24    6     200  12
TERRACE      ANT       9    3     200  10     20    4     300  12
STEWART      ANT       9    3      50   6     15    4     150   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
VANCOUVER    S   11   SW  13   W   17
PORT HARDY   S   63   S   46   SW  57
SANDSPIT     S   98   SW  98   SW 102

TODAY'S VENTING: POOR.

VENTING FOR FRIDAY: POOR

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


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