FPCN39 CWLW 071457
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 WEDNESDAY 7 MAY 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      17   12     750   2    100   21    3200   9
KAMLOOPS     KEL     100   13    3350   9    100   21    3350   9
OKANAGAN     KEL     100   13    3350   9    100   19    3350   8
CASTLEGAR    SPOK     48   11    1100   8    100   19    3500   8
CRANBROOK    SPOK    100    9    3950   9    100   17    3950   9
REVELSTOKE   KEL      23   10     950   3    100   16    3450   9

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

FORECAST UPPER WINDS FOR WEDNESDAY AFTERNOON (WINDS IN KM/H):
             900m     1800m    2700m
PENTICTON    VR   5   VR   5   VR   5
CRANBROOK             VR   5   NW  13

           INVERSION HT    BREAKTHRU TEMP
KELOWNA         900 m         12 C
SPOKANE         800 m          8 C

TODAY'S VENTING: becoming good by late morning.

VENTING FOR THURSDAY: fair to poor with a ridge of high pressure
building in.

VENTING OUTLOOK FRIDAY THRU SUNDAY: Good with moderate winds as
the ridge remains offshore.


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.     60    8    1050   8    100   16    3950  12
PR. GEORGE   P.G.     89    9    1350   8    100   14    3700  12
SMITHERS     P.G.     69    8    1150   4    100   15    3500  10
WELLS GRAY   P.G.     70    9    1100   7    100   16    4000  17
FT NLSN      F.N.     34    7     800   7     96   13    2050  10
FT STJOHN    F.N.     71    8     900   8    100   14    3700  10

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

FORECAST UPPER WINDS FOR WEDNESDAY AFTERNOON (WINDS IN KM/H):
             900m     1800m    2700m
PR. GEORGE            SW  17   SW  24
SMITHERS              SW  19   SW  24

           INVERSION HT    BREAKTHRU TEMP
PR. GEORGE      1370 m         11# C
FT. NELSON      2100 m         13 C

TODAY'S VENTING: becoming good by late in the morning.

VENTING FOR THURSDAY: fair to good as a ridge of high pressure
builds in.

VENTING OUTLOOK FRIDAY THRU SUNDAY: Good with moderate winds as
the ridge remains offshore.

COAST

           UPPER      ***** MORNING ******    ***** AFTERNOON ****
             AIR      VI  Tmp  MXG HT  Wnd    VI  Tmp  MXG HT  Wnd
                               (mASL)  (kt)            (mASL)  (kt)
VANCOUVER    QUIL     11   12     300   4     45   16    1100   5
FRASER VLY   QUIL     11   12     300   2     28   18    1100   2
SRN VRISL    QUIL     14   11     300   5     48   16    1100   6
CNTRL VRISL  QUIL     13   13     300   6     45   18    1100   5
NRN VRISL    HRDY     30   11     300   4     75   15    1100  10
TERRACE      ANT      30   10     350  18     68   14     800  13
STEWART      ANT      35   10     350  14     58   13     600  13

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

FORECAST UPPER WINDS FOR WEDNESDAY AFTERNOON (WINDS IN KM/H):
             900m     1800m    2700m
VANCOUVER    VR   5   E    9   VR   5
PORT HARDY   VR   5   S   17   SW  13
SANDSPIT     S   39   S   39   S   39

           INVERSION HT    BREAKTHRU TEMP
QUILLAYUTE       640 m         11 C
PORT HARDY       300 m          9 C
ANNETTE          210 m          9 C

TODAY'S VENTING: poor to fair on the south coast as a ridge
of high pressure stabilizes the region.  fair to good on the
north coast as the airmass remains unstable and winds are
higher.

VENTING FOR THURSDAY: fair

VENTING OUTLOOK FRIDAY THRU SUNDAY: Good Friday becoming fair
to good on Saturday and Sunday as a ridge of high pressure
builds but winds remain moderate to strong.


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

END/lm