Propagation Forecast Bulletin 49 ARLP049
From Tad Cook, K7RASeattle, WA
November 26, 2007
To all radio amateurs
SB PROP ARL ARLP049ARLP049 Propagation de K7RA This is an off-schedule post-Thanksgiving bulletin. Because ARRLheadquarters was closed on Friday, the day this bulletin is normallyreleased, and the last Propagation Forecast Bulletin ARLP048 waswritten before the end of our reporting week (which is Thursdaythrough Wednesday), the sunspot, solar flux and geophysical numbersnormally at the end of the bulletin are in this bulletin, but werenot a part of ARLP048. Friday, November 30 will find us back on theregular schedule with Propagation Forecast Bulletin ARLP050.
The last propagation bulletin reported a brief return of sunspots onNovember 16-17, when sunspot group 974 emerged, and the sunspotnumber was 13 on both days. There were six more days of no spots,then November 24 saw the emergence of group 975, with a sunspotnumber of 15. The next day the sunspot number declined to 12, andthe area it covered was about half the area on the previous day.
A solar wind stream on November 20 caused the most active recentgeomagnetic day, with the planetary A index rising to 28, andAlaska's high-latitude college A index going to 48. Geomagneticindices were somewhat unsettled over the last weekend (November24-25), but are quieting down now, with the expected planetary Aindex at 10 for today, November 26, and then 5 until December 11.The planetary A index over November 22-25 was 13, 10, 12, and 11.The numbers for the seven days previous to that are listed below.
Unexpected bottom-of-the-cycle propagation still crops up. OnNovember 21, a number of Northeast United States stations reportedworking Central and South America on 10 meters. W1RM workedMozambique on 12 meters and Ecuador on 10 meters.
In Propagation Forecast Bulletin ARLP047 on November 16 we mentionedbriefly some unusual daylight DX on 75 meters. Note that most ofthese stations had what many of us would consider monsterdirectional antenna arrays for 75 meters, such as 2-3 element Yagisanywhere from 100-165 feet.
If you would like to make a comment or have a tip for our readers,email the author at, k7ra@arrl.net.
For more information concerning radio propagation, see the ARRLTechnical Information Service at,http://www.arrl.org/tis/info/propagation.html.
For a detailedexplanation of the numbers used in this bulletin go to: http://www.arrl.org/tis/info/k9la-prop.html.
An archive of pastpropagation bulletins is at, http://www.arrl.org/w1aw/prop/. Monthlypropagation charts between four USA regions and twelve overseaslocations are at, http://www.arrl.org/qst/propcharts/.
Sunspot numbers for November 15 through 21 were 0, 13, 13, 0, 0, 0and 0 with a mean of 3.7. 10.7 cm flux was 69.2, 70.6, 69.8, 68.8,69.5, 69.7, and 69.1 with a mean of 69.5. Estimated planetary Aindices were 5, 6, 5, 2, 3, 28 and 13 with a mean of 8.9 Estimatedmid-latitude A indices were 5, 5, 5, 1, 2, 10 and 9, with a mean of5.3.NNNN/EX(Source: ARLP049 Propagation de K7RA via Dave Raycroft/ODXA)
Product: Weekly Highlights and Forecasts:Issued: 2007 Nov 27 1854 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
# http://www.swpc.noaa.gov/weekly.html
Highlights of Solar and Geomagnetic Activity
19 - 25 November 2007
Solar activity was very low. New Region 975 (N02, L=103, class/area, Bxo/020 on 25 November) formed on the solar disk on the 24th.
No proton events were observed at geosynchronous orbit.
The greater than 2 MeV electron flux at geosynchronous orbit was at high levels on the 19, 22, and 24 - 25 November.
The geomagnetic field was at quiet to major storm levels on 19 - 20 November. Activity decreased to quiet to active levels through the remainder of the period. ACE solar wind measurements indicated a recurrent co-rotating interaction region (CIR) late on 19 November
in advance of a coronal hole high speed stream which arrived late on 20 November. During the CIR, the Interplanetary Magnetic Field (IMF) Bt peaked at 20 nT (20/1122 UTC), with a variable Bz of +10 nT to -17 nT. Wind velocities increased to a maximum of 702 km/sec
(21/0920 UTC) during the coronal hole high speed stream. Wind speed gradually declined until mid day on 22 November when another coronal hole high speed stream was detected at ACE.
Maximum wind speed values are uncertain due to a gap in data acquisition (22/2138 -
23/0654 UTC). Wind speed before and after the gap was in the 620 - 630 km/s range. Bt reached at peak of 11 nT (22/1657 UTC), and Bz ranged from +9 nT to -8 nT. Wind speed again declined until mid day on 24 November, when yet another coronal hole high speed stream
became geoeffective. The maximum speed for this stream was uncertain due to another data acquisition gap (24/2137 - 25/0031 UTC), however, the wind speed after the gap was at approximately 640 km/s.
Forecast of Solar and Geomagnetic Activity
28 November - 24 December 2007
Solar activity is expected to be very low.
No proton events are expected at geosynchronous orbit.
The greater than 2 MeV electron flux at geosynchronous orbit is expected to reach high levels during 01, 16, and 18 - 24 December.
Activity is expected to be at predominantly quiet levels 28 November - 16 December. Geomagnetic activity may increase to quiet to unsettled conditions on 11 - 13 December. Activity is expected to increase to active to minor storm levels on 17 - 18 December as a
coronal hole high speed stream becomes geoeffective. From 19 - 23 December, activity should be unsettled to active due to a series of coronal hole high speed streams. Activity should decline to mostly quiet levels on 24 December.
Product: 27-day Space Weather Outlook Table 27DO.txt
:Issued: 2007 Nov 27 1854 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
# http://www.swpc.noaa.gov/wwire.html
#
# 27-day Space Weather Outlook Table
# Issued 2007 Nov 27
#
# UTC Radio Flux Planetary Largest
# Date 10.7 cm A Index Kp Index
2007 Nov 28 70 5 2
2007 Nov 29 70 5 2
2007 Nov 30 70 5 2
2007 Dec 01 68 5 2
2007 Dec 02 68 5 2
2007 Dec 03 68 5 2
2007 Dec 04 68 5 2
2007 Dec 05 70 5 2
2007 Dec 06 70 5 2
2007 Dec 07 70 5 2
2007 Dec 08 70 5 2
2007 Dec 09 70 5 2
2007 Dec 10 70 5 2
2007 Dec 11 70 10 3
2007 Dec 12 70 10 3
2007 Dec 13 70 10 3
2007 Dec 14 70 5 2
2007 Dec 15 68 5 2
2007 Dec 16 68 5 2
2007 Dec 17 68 20 5
2007 Dec 18 68 15 4
2007 Dec 19 68 15 4
2007 Dec 20 68 10 3
2007 Dec 21 68 15 4
2007 Dec 22 68 10 3
2007 Dec 23 68 8 3
2007 Dec 24 68 5 2
(NOAA)