FPCN39 CWLW 171346
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 FRIDAY 17 APRIL 1998 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      49   12    1100   5    100   18    3200   8
KAMLOOPS     KEL      50   11    1400   5    100   18    3350   8
OKANAGAN     KEL      13    8     550   2    100   16    3350   8
CASTLEGAR    SPOK     31    8     950   5    100   16    3500   6
CRANBROOK    SPOK     25    7    1350   4    100   14    3950   7
REVELSTOKE   KEL      11    7     550   2    100   15    3450   8

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

FORECAST UPPER WINDS FOR FRIDAY AFTERNOON (WINDS IN KM/H):
             900m     1800m    2700m
PENTICTON    VR   5   VR   5   VR   5
CRANBROOK             VR   5   VR   5

           INVERSION HT    BREAKTHRU TEMP
KELOWNA          540 m          8 C
SPOKANE         1040 m          8 C

TODAY'S VENTING: GOOD

VENTING FOR SATURDAY: FAIR

VENTING OUTLOOK SUNDAY THRU TUESDAY: FAIR

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.     20    5    1200   4     84   12    3950   4
PR. GEORGE   P.G.      9    5     700   2     72   12    3700   3
SMITHERS     P.G.      9    6     750   0     32   12    1750   2
WELLS GRAY   P.G.     20    5    1300   4     84   13    4000   4
FT NLSN      F.N.     MISSING
FT STJOHN    F.N.     MISSING

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

FORECAST UPPER WINDS FOR FRIDAY AFTERNOON (WINDS IN KM/H):
             900m     1800m    2700m
PR. GEORGE            S   20   S   30
SMITHERS              S   43   S   30

           INVERSION HT    BREAKTHRU TEMP
PR. GEORGE       900 m          9 C
FT. NELSON      MISSING

TODAY'S VENTING: GOOD EXCEPT POOR IN THE NORTHWEST

VENTING FOR SATURDAY: POOR

VENTING OUTLOOK SUNDAY THRU TUESDAY: GOOD

COAST

           UPPER      ***** MORNING ******    ***** AFTERNOON ****
             AIR      VI  Tmp  MXG HT  Wnd    VI  Tmp  MXG HT  Wnd
                               (mASL)  (kt)            (mASL)  (kt)
VANCOUVER    QUIL     22    9     500   3     61   13    1550   5
FRASER VLY   QUIL     20    9     450   3     67   16    1800   5
SRN VRISL    QUIL     30    9     300   8     67   14    1550   5
CNTRL VRISL  QUIL     41   10     700   6     67   14    1550   5
NRN VRISL    HRDY     17   10     250   4     60   12     850   8
TERRACE      ANT     100    8     700  39    100   12    1450  46
STEWART      ANT     100   10     700  33    100   12    1200  38

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

FORECAST UPPER WINDS FOR FRIDAY AFTERNOON (WINDS IN KM/H):
             900m     1800m    2700m
VANCOUVER    VR   5   S   17   S   13
PORT HARDY   S   57   S   63   S   54
SANDSPIT     S   78   S   70   S   69

           INVERSION HT    BREAKTHRU TEMP
QUILLAYUTE       250 m          8 C
PORT HARDY       190 m         10 C
ANNETTE         NONE

TODAY'S VENTING: GOOD

VENTING FOR SATURDAY: GOOD

VENTING OUTLOOK SUNDAY THRU TUESDAY: GOOD

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


END/PJS