Report of Solar-Geophysical Activity 24 Feb

:Product: Report of Solar-Geophysical Activity

:Issued: 2000 Feb 24 2210 UT

# Prepared jointly by the U.S. Dept. of Commerce, NOAA,

#Space Environment Center and the U.S. Air Force.

#

JOINT USAF/NOAA REPORT OF SOLAR AND GEOPHYSICAL ACTIVITY

SDF NUMBER 055 ISSUED AT 2200Z ON 24 FEB 2000

IA.  ANALYSIS OF SOLAR ACTIVE REGIONS AND ACTIVITY FROM  23/2100Z

TO 24/2100Z:  SOLAR ACTIVITY WAS MODERATE. AN OPTICALLY UNCORRELATED

M1 FLARE OCCURRED AT 24/0111Z. THERE ARE SOME TENTATIVE INDICATIONS

THAT THIS EVENT ORIGINATED FROM NEW REGION 8889 NEAR N19E67. THIS

REGION IS A MODERATE SIZE D CLASS GROUP BUT FORESHORTENING MAY BE

MASKING ITS TRUE SIZE. A TOTAL OF THREE OTHER REGIONS IN THE EASTERN

HEMISPHERE BECAME VISIBLE BUT, AT THIS TIME, NONE APPEARED LARGE OR

COMPLEX. THERE MAY BE ONE OR MORE REGIONS STILL BEHIND THE EAST

LIMB.

IB.  SOLAR ACTIVITY FORECAST:  SOLAR ACTIVITY SHOULD BE PREDOMINANTLY

MODERATE FOR THE NEXT THREE DAYS. THE POSSIBILITY OF A MAJOR FLARE

FROM NEAR EAST LIMB REGIONS IS A POSSIBILITY. ONCE THESE LONGITUDES

BECOME VISIBLE, A BETTER ASSESSMENT WILL BE POSSIBLE.

IIA.  GEOPHYSICAL ACTIVITY SUMMARY FROM 23/2100Z TO 24/2100Z:

THE GEOMAGNETIC FIELD BEGAN THE PERIOD AT QUIET LEVELS AND WAS AT

ACTIVE TO MINOR STORM LEVELS AFTER 24/0300Z. SOLAR WIND VELOCITY

INCREASED TO SLIGHTLY OVER 800 KM/S AND DENSITY DECLINED TO LOW

LEVELS INDICATING THE EARTH IS IMMERSED IN THE PREVIOUSLY FORECAST

CORONAL HOLE STREAM. THE SOURCE HOLE ON THE SUN IS SLIGHTLY MORE

ELONGATED THAN LAST SOLAR ROTATION.

IIB.  GEOPHYSICAL ACTIVITY FORECAST:  THE GEOMAGNETIC FIELD SHOULD BE

PREDOMINANTLY UNSETTLED TO ACTIVE FOR 25-26 FEB. OCCASIONAL PERIODS

OF MINOR STORMING ARE LIKELY DURING THAT PERIOD. THIS CORONAL HOLE

RELATED DISTURBANCE SHOULD BEGIN TO EBB ON 27 FEB WHEN QUIET TO

SLIGHTLY ACTIVE CONDITIONS ARE EXPECTED. ENERGETIC ELECTRON FLUXES

AT GEOSYNCHRONOUS ORBIT SHOULD BECOME ELEVATED TO HIGH LEVELS ON 25

FEB.

III.  EVENT PROBABILITIES 25 FEB-27 FEB

CLASS M    75/75/75

CLASS X    10/10/10

PROTON     05/05/05

PCAF       GREEN

IV.  PENTICTON 10.7 CM FLUX

OBSERVED           24 FEB 192

PREDICTED   25 FEB-27 FEB  195/197/200

90 DAY MEAN        24 FEB 164

V.  GEOMAGNETIC A INDICES

OBSERVED AFR/AP 23 FEB  008/009

ESTIMATED AFR/AP 24 FEB  024/023

PREDICTED AFR/AP 25 FEB-27 FEB  025/020-018/018-012/015

VI.  GEOMAGNETIC ACTIVITY PROBABILITIES 25 FEB-27 FEB

A.  MIDDLE LATITUDES

ACTIVE                40/50/30

MINOR STORM           35/25/15

MAJOR-SEVERE STORM    05/05/01

B.  HIGH LATITUDES

ACTIVE                40/50/30

MINOR STORM           40/25/15

MAJOR-SEVERE STORM    10/05/01