ARRL

ARRL Propagation Bulletin ARLP025 (2000)

SB PROP @ ARL $ARLP025
ARLP025 Propagation de K7VVV

ZCZC AP25
QST de W1AW  
Propagation Forecast Bulletin 25  ARLP025
From Tad Cook, K7VVV
Seattle, WA  June 23, 2000
To all radio amateurs 

SB PROP ARL ARLP025
ARLP025 Propagation de K7VVV

Average solar flux and sunspot numbers rose slightly this week, and
geomagnetic indices were lower. Planetary and mid-latitude A indices
have been mostly in the single digits. Unfortunately, geomagnetic
conditions may be a bit more active for Field Day this weekend. The
predicted planetary A index for Friday through Tuesday is 15, 15,
20, 20 and 12, but no major disturbance is likely. Solar flux for
the same period is expected to be around 175, 175, 170, 165 and 165,
and should begin rising again around July 1. The short term outlook
is for flux values to slowly rise and then peak around 200 before
the middle of next month.

NASA has an article this week on a proposed model for better
predicting the arrival time of the effects from Coronal Mass
Ejections. You can see the NASA article at
http://science.nasa.gov/headlines/y2000/ast22jun_1m.htm?list and see
more info from a solar physics meeting at
http://www.lmsal.com/spd/Press/ .

Here is a forecast for this Field Day weekend.

From the East Coast of the United States to the center of the
contiguous 48 states, check 80 meters 0000-1200z (best 0200-0400z),
40 meters all hours, best 0130-0900z with a peak at sunset in the
Midwest around 0200z, and weakest 1700-1900z, 20 meters also open
all hours, strongest around 2330z, 15 meters possibly open
0630-1400z.

From the East Coast to the West Coast, 80 meters 0300-1030z (best
around 0430z), 40 meters 0100-1200z (best 0430-0900z), 20 meters
open around the clock, best 0400-0600z, weakest 1730-2000z, 15
meters possibly open during the early morning.

From the West Coast to the Midwest, 80 meters 0230-1230z (best
0500-1030z), 40 meters open all hours, strongest 0430-1030z, weakest
1830-2030z, 20 meters open all hours, best 0400-1100z, weakest
1800-2100z. 15 meters could possibly open at any time.

It looks like the best band will be 40 meters. There is also a
possibility of 10 meter sporadic E skip openings during the day.

Sunspot numbers for June 15 through 21 were 261, 252, 211, 250, 194,
219 and 226 with a mean of 230.4. 10.7 cm flux was 202.4, 197.5,
193.1, 187.6, 178.4, 183.7 and 188, with a mean of 190.1, and
estimated planetary A indices were 20, 9, 10, 11, 9, 9 and 8, with a
mean of 10.9.
NNNN
/EX