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PROPAGATION FORECAST BULLETIN 10  ARLP010
FROM TAD COOK, KT7H, SEATTLE, WA
MARCH 12, 1993
TO ALL RADIO AMATEURS

HIGH SOLAR ACTIVITY OVER THE PAST WEEK PRODUCED SOME INTERESTING
EFFECTS ON HF PROPAGATION, ALTHOUGH NOT ALL OF IT WAS THE TYPE THAT
RADIO AMATEURS LIKE TO SEE.

SOLAR FLUX JUST PRIOR TO THE ARRL DX CONTEST WAS QUITE HIGH, BUT IT
WAS FOLLOWED BY A MAJOR FLARE ON MARCH 6.  MOST OF THE EFFECTS OF
THE DISTURBANCE WERE DELAYED UNTIL AFTER THE CONTEST.  THE
DISTURBANCE ACTUALLY ARRIVED ON EARTH AT 2139 UTC ON MARCH 8.  ON
MARCH 9 THE PLANETARY A INDEX REACHED AN EXTREMELY HIGH VALUE OF 78,
AND K VALUES WENT AS HIGH AS EIGHT.  THIS HUGE RELEASE OF SOLAR
ENERGY PRODUCED AURORAL ACTIVITY, BUT THE PHASE OF THE MOON PROBABLY
HAMPERED VIEWING ATTEMPTS IN MANY AREAS.

WE CAN EXPECT MORE UNSETTLED TO ACTIVE CONDITIONS IN THE WEEK AHEAD.
BASED ON THE PREVIOUS SOLAR ROTATION, LOOK FOR DISTURBED CONDITIONS
AGAIN AROUND MARCH 21, AND TO A LESSER EXTENT MARCH 27.  SOLAR FLUX
SHOULD DROP TO A LOW NEAR 125 AROUND MARCH 18, AND THEN HEAD BACK UP
AGAIN TOWARD 160 AROUND THE END OF THE MONTH.

AS WE HEAD INTO THE SPRING SEASON, WE CAN EXPECT SEASONAL
IMPROVEMENT ON THE HF BANDS.

THE PROPAGATION PROJECTION FOR THIS WEEK IS FROM ATLANTA, GEORGIA TO
SYDNEY, AUSTRALIA.  80 METERS SHOULD BE OPEN FROM 0730 TO 1230 UTC,
AND BEST FROM 0830 TO 1100 UTC.  40 METERS SHOULD BE BEST FROM 0730
TO 1300 UTC, AND 30 METERS FROM 0630 TO 1330 UTC.  20 METERS SHOULD
BE BEST FROM 0530 TO 1430 UTC.  17 METERS MAY BE MARGINAL OVER THIS
PATH, WITH THE BEST OPENING FROM 0300 TO 0400 UTC.  15 METERS SHOULD
HAVE SOME OPENING IN THE LATE AFTERNOON ON THE NORTH AMERICAN END OF
THE PATH, WITH THE BEST PERIOD FROM 0130 TO 0300 UTC.  12 METERS
SHOULD BE SIMILAR, BUT THE BEST TIME WOULD BE AROUND 0100 UTC.  10
METERS WILL PROBABLY BE MARGINAL, BUT CHECK AROUND LATE AFTERNOON OR
SUNSET ON THE NORTH AMERICAN END.

SUNSPOT NUMBERS FROM MARCH 4 TO 10 WERE 156, 163, 149, 144, 159, 102
AND 127, WITH A MEAN OF 142.9.  10.7 CM FLUX WAS 166.5, 165.2,
166.6, 153.2, 146.4, 142.6 AND 148.7, WITH A MEAN OF 155.6.
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