FPCN39 CWLW 291422
REVISED 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 WEDNESDAY 29 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       9   16     600   0     98   26    2500   7
KAMLOOPS     KEL      16   16     650   2     50   27    2100   3
OKANAGAN     KEL       9   13     550   0     50   24    2100   3
CASTLEGAR    SPOK     21   15     900   3     49   24    2100   3
CRANBROOK    SPOK     21   13     600   2     90   23    2500   5
REVELSTOKE   KEL       9   13     600   0     50   23    2100   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 WEDNESDAY AFTERNOON (WINDS IN KM/H):
             900m     1800m    2700m
PENTICTON    VR   5   SW   9   SW  19
CRANBROOK             VR   5   W   19

           INVERSION HT    BREAKTHRU TEMP
KELOWNA          800 m         21 C
SPOKANE         1000 m         21 C

TODAY'S VENTING: Poor this morning becoming good this afternoon.


VENTING FOR THURSDAY: Fair.


VENTING OUTLOOK FRIDAY THRU SUNDAY: 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.    100   12    2050  23    100   22    3950  25
PR. GEORGE   P.G.     79   12    1450  14    100   21    3700  21
SMITHERS     P.G.     10    9     650   1     99   15    1800  13
WELLS GRAY   P.G.    100   12    2300  23    100   22    4000  25
FT NLSN      F.N.    100   11    1050  30    100   15    2950  27
FT STJOHN    F.N.    100   11    2850  26    100   16    3700  27


*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            W    9   W   24
SMITHERS              S   13   SW  24

           INVERSION HT    BREAKTHRU TEMP
PR. GEORGE       800 m         12 C
FT. NELSON       none          n/a

TODAY'S VENTING: Good.


VENTING FOR THURSDAY: GOOD


VENTING OUTLOOK FRIDAY THRU SUNDAY: Good.


COAST

           UPPER      ***** MORNING ******    ***** AFTERNOON ****
             AIR      VI  Tmp  MXG HT  Wnd    VI  Tmp  MXG HT  Wnd
                               (mASL)  (kt)            (mASL)  (kt)
VANCOUVER    QUIL     17   13     350   3     21   18     500   3
FRASER VLY   QUIL     21   18     450   3     47   26    1550   3
SRN VRISL    QUIL     19   14     350   3     25   20     600   3
CNTRL VRISL  QUIL     20   16     400   3     39   25    1300   3
NRN VRISL    HRDY     39   12     350  10     67   17     700  11
TERRACE      ANT      58    9    1100   7    100   13    2000  10
STEWART      ANT      50   10     700   7    100   13    1850  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
VANCOUVER    E   13   S   15   SW  20
PORT HARDY   VR   5   SE  19   S   22
SANDSPIT     S   41   S   43   S   46

           INVERSION HT    BREAKTHRU TEMP
QUILLAYUTE      1700 m         27 C
PORT HARDY       800 m         16 C
ANNETTE          200 m          8 C

TODAY'S VENTING: Poor on the south coast becoming good on the North
Coast.


VENTING FOR THURSDAY: POOR IN THE SOUTH. GOOD IN THE NORTH.


VENTING OUTLOOK FRIDAY THRU SUNDAY: GOOD.


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


END/GF