EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
AFDSAN 350 AM PST FRI FEB 1 2002
.SYNOPSIS...HIGH PRESSURE OVER THE GREAT BASIN IS MOVING SOUTHEAST.
THIS WILL BRING GUSTY EAST WINDS AND WARMER TEMPERATURES TODAY. A
WEAK UPPER LEVEL TROUGH WILL SPREAD HIGH CLOUDS ACROSS SOUTHWEST
CALIFORNIA LATER TODAY. THESE SHOULD MOVE SOUTH AND EAST OF THE AREA
TONIGHT. OVER THE WEEKEND FAIR WEATHER AND MILD TEMPERATURES ARE
EXPECTED. ALONG THE COAST DENSE FOG MAY BE PRESENT DURING THE NIGHT
AND MORNING HOURS.
.DISCUSSION...
SATELLITE IMAGERY SHOWS CIRRUS STREAKS APPROACHING FROM SW AND NW
AHEAD OF TWO WEAK UPPER LEVEL TROUGHS THAT THE MODELS MERGE INTO ONE
WITH AN AXIS ALONG 118W LONGITUDE BY 02/00Z. THIS TROUGH THEN MOVES
SLOWLY EASTWARD ACROSS FORECAST AREA THROUGH SUNDAY. BY SUNDAY
AFTERNOON RIDGE HAS BUILT ALONG WEST COAST. THIS RIDGE AXIS MOVES
INLAND TO OUR LONGITUDE MONDAY WITH HEIGHTS OF 576 THEN IT IS
QUICKLY FLATTENED TUESDAY AND WEDNESDAY BUT LITTLE CHANGE IN
HEIGHTS/THICKNESSES. ASIDE FROM THE INCREASE IN CIRRUS TODAY AHEAD
OF THE TROUGH...MODELS ARE DRY AT MID AND UPPER LEVELS WITH AS THE
TROUGH MOVES INLAND. THUS HAVE CHANGED PARTLY CLOUDY FORECAST GROUND
HOG DAY AND SUNDAY TO MOSTLY CLEAR. FOR THE LOWER LEVELS...THE 1035
MB HIGH OVER UTAH SLIPPING SE WILL PROVIDE ANOTHER DAY OF MODERATE
OFFSHORE FLOW. MESOETA MODELS HAS 850 MB WINDS E 25-30 KT THIS
MORNING ACROSS MOUNTAINS OF SAN DIEGO COUNTY/NORTHERN BAJA
DIMINISHING TO E 15KT BY 18Z. RAWS REPORTS FROM SAN JACINTO/SANTA
ROSA/LAGUNA MTNS SUPPORT THIS SHOWING GUSTS 20-27 MPH...AS DOES 06Z
ACARS SOUNDING VICINITY PHOENIX. SUBSIDENCE WARMING SHOW ON 01/00Z
SOUNDINGS ABOVE 800 MB...EXPECT IT WILL HAVE WORKED DOWN TO 900 MB
BY 01/12Z...EXPECT MOST MOUNTAIN AND LOCATIONS TO THE WEST WILL BE
ABOUT 10 DEGREES WARMER TODAY. WILL REVIEW 01/12Z MORNING SOUNDINGS
AND IF MORE WARMING SHOWN THAN ANTICIPATED ISSUE AN UPDATE AROUND 6
AM. WEAKENING OFFSHORE FLOW TODAY AND SWITCH TO ONSHORE FLOW
SATURDAY SHOULD RESULT IN PERIOD OF DENSE FOG ALONG COAST. DECIDED
AT LAST MINUTE TO LEAVE FOG OUT OF TONIGHT FORECAST AS OFFSHORE FLOW
SHOULD STILL BE DOMINATE. WILL SHOW SOME CLOUDS FOR SATURDAY AND
SUNDAY. THE MEDIUM RANGE MODELS ARE STILL IN AGREEMENT THROUGH
TUESDAY BUT AFTER THIS THEY ARE NO LONGER IN PHASE...PROBABLY DUE TO
INITIALIZATION DIFFERENCES IN FAST MOVING SHORT WAVES EMBEDDED IN
STRONG ZONAL FLOW UPSTREAM. MRF SHOWS RIDGE REBUILDING AFTER
WEDNESDAY WITH HEIGHTS ABOVE 5820 METERS BY NEXT SATURDAY...BUT IT
MAY BE OVERDONE.
.SAN...FREEZE WARNINGS AND FROST ADVISORIES...SEE LAXNPWSAN.
BALFOUR
SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
AFDDTX 1020 AM EST FRI FEB 1 2002
...WIND ADVISORIES WILL REMAIN UNTIL NOON...
LATEST METARS CONTINUE TO GUST OVER 45 MPH WITH A FEW REPORTS TO
NEAR 50 MPH. LATEST VAD WIND PROFILE (VCP 32) FROM THE 88D NICELY
DEPICTS 50+KTS JUST OFF THE DECK (2-3K FEET) AND THIS IS VERIFIED
WITH LATEST ACARS INFORMATION INTO KDTW THIS MORNING AND RUC40
SKEW-T. RUC40 SOUNDINGS OVER SOUTHERN LAKE MICHIGAN AND POINTS
INLAND SHOW IMPRESSIVE COLD AIR ADVECTION WITH LAKE EFFECT
SNOW/ENHANCEMENT FOR THIS AFTERNOON (DELTA T/S NEAR 15C).
DEFORMATION AXIS SHOULD REMAIN MAINLY NORTH OF THE CWA WITH ITS
AFFECTS CLIPPING THE THUMB AND TRI-CITIES REGION BRIEFLY. INTO THE
AFTERNOON THE RUC40 SOUNDINGS SHOW LOWERING INVERISON HEIGHTS WHICH
WILL INHIBIT SNOW AND WIND POTENTIAL FOR THE AFTERNOON.
WE WILL ISSUE ANOTHER UPDATE TOWARD NOON AND REEVALUATE THE
HEADLINES FOR THE SOUTHERN SECTIONS OF THE CWA.
.DTX...HIGH WIND ADVISORY...UNTIL NOON...MI060>063-068>070-
075>076-082>083.
GALE WARNING...THIS AFTERNOON...LAKE HURON.
GALE WARNING...THIS AFTERNOON...LAKE ST. CLAIR.
BGM