FPCN39 CWLW 201321
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 MONDAY 20 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      13    9     600   1     72   17    1650   6

KAMLOOPS     KEL      23    9     700   4     96   18    2600   7

OKANAGAN     KEL      11    7     550   1     87   17    2200   7

CASTLEGAR    SPOK     17   10     750   3     59   18    2450   3

CRANBROOK    SPOK      9    8     950   4     84   16    3950   4

REVELSTOKE   KEL      19    8     700   4     85   16    2200   7


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

FORECAST UPPER WINDS FOR MONDAY AFTERNOON (WINDS IN KM/H):
             900m     1800m    2700m
PENTICTON    VR   5   S   22   SW  33
CRANBROOK             S   11   S   30

           INVERSION HT    BREAKTHRU TEMP
KELOWNA          680 m          8 C
SPOKANE          980 m         10 C

TODAY'S VENTING: GOOD

VENTING FOR TUESDAY: GOOD

VENTING OUTLOOK WEDNESDAY THRU FRIDAY: 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.     72    5    2150   8    100   13    3950  11

PR. GEORGE   P.G.     16    3     800   7    100   12    3700  10

SMITHERS     P.G.     22    5     800   5     99   11    2650   8

WELLS GRAY   P.G.     58    4    1950   7    100   13    4000  11

FT NLSN      F.N.     18    5     450  12    100   11    2500  27

FT STJOHN    F.N.     69    6    1050  23    100   12    3700  29


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

FORECAST UPPER WINDS FOR MONDAY AFTERNOON (WINDS IN KM/H):
             900m     1800m    2700m
PR. GEORGE            S   26   S   43
SMITHERS              SE  28   S   43

           INVERSION HT    BREAKTHRU TEMP
PR. GEORGE       830 m          5 C
FT. NELSON       610 m          9 C

TODAY'S VENTING: GOOD

VENTING FOR TUESDAY: GOOD

VENTING OUTLOOK WEDNESDAY THRU FRIDAY: GOOD

COAST

           UPPER      ***** MORNING ******    ***** AFTERNOON ****
             AIR      VI  Tmp  MXG HT  Wnd    VI  Tmp  MXG HT  Wnd
                               (mASL)  (kt)            (mASL)  (kt)
VANCOUVER    QUIL     19    9     200   7     71   14    1600   6

FRASER VLY   QUIL     22   10     250   7     85   17    1950   7

SRN VRISL    QUIL     23    9     200   8     77   16    1650   6

CNTRL VRISL  QUIL     22    7     200   9     54   13     950   6

NRN VRISL    HRDY     22    6     150  10     76   12     800  13

TERRACE      ANT      10    5     250  17    100   10    3200  21

STEWART      ANT       9    5       0   6     93   10    1000  15


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

FORECAST UPPER WINDS FOR MONDAY AFTERNOON (WINDS IN KM/H):
             900m     1800m    2700m
VANCOUVER    S   19   S   35   SW  52
PORT HARDY   S   50   S   61   SW  63
SANDSPIT     S   83   S   78   S   61

           INVERSION HT    BREAKTHRU TEMP
QUILLAYUTE       580 m         13 C
PORT HARDY       800 m         12 C
ANNETTE          180 m          8 C

TODAY'S VENTING: GOOD

VENTING FOR TUESDAY: GOOD

VENTING OUTLOOK WEDNESDAY THRU FRIDAY: GOOD

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


END/PJS