EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
AFDSAN 900 PM PDT MON SEP 6 1999
...SYNOPSIS...
WEAK HIGH PRESSURE WILL BUILD WESTWARD INTO SOUTHERN CALIFORNIA
THROUGH WEDNESDAY WITH A WARMING TREND INLAND...GREATEST IN THE
INLAND VALLEYS...WITH NIGHT AND MORNING LOW CLOUDS CONFINED CLOSER
TO THE COAST. MOISTURE FROM HURRICANE "GREG"...CURRENTLY SOUTHEAST
OF THE SOUTHERN TIP OF BAJA CALIFORNIA...MAY BEGIN TO SPREAD
NORTHWARD ACROSS SOUTHERN CALIFORNIA WEDNESDAY.
...DISCUSSION...
THE WLYS REMAIN DISPLACED WELL TO THE N OF SRN CA...ACROSS THE
NORTHEASTERN PAC AND THE NRN TIER OF STATES WITH A WK UPR TROUGH
MOVG INLAND ACROSS THE PAC NW AND THE NEXT UPSTREAM TROUGH JUST S OF
THE ALEUTIANS. A WK CUTOFF UPR LOW REMAINS TO THE SW OF SRN CA...CNTRD NR
30N/125W...WITH A WK UPR RDG TO THE E OF SRN CA...AND HURRICANE
"GREG" TO THE SE OF THE SRN TIP OF BAJA. RADAR IMAGERY FM CABO
(HTTP://WWW.CNA.GOB.MX/RADARES/RAD-CABO.GIF) SHOWS MOST CONVECTION
IN THE SW SEMICIRCLE WITH THE EYE EXPOSED ON THE NORTHEAST SIDE.
DURG THE NEXT 24 HOURS...THE UPR RDG TO THE E OF SRN CA WL BUILD
SLOWLY WWD WITH SLOWING RISING HEIGHTS AND THICKNESSES ACROSS SRN CA
AND A CORRESPONDING LWRG AND STRENGTHENING OF THE MARINE INVERSION.
AS THE PAC NW UPR TROUGH MOVES INLAND TUE AND AMPLIFIES OVR THE NRN
PLAINS STATES WED...TRAILING SURFACE HIGH PRESSURE WL BUILD OVR THE
INTERIOR W (NRN AND CNTRL ROCKIES INTO THE GREAT BASIN). THIS WL
RESULT IN OFSHR SURFACE PRESSURE GRADIENT TRENDS INTO SRN CA AT
NIGHT FOR TUE NIGHT AND WED NIGHT WITH A DELAY IN THE AFTERNOON SEA
BREEZE AND ASSOCD COOLING FOR THE VLYS FOR WED AND THU. THIS SHOULD
RESULT IN A DECIDED WARMING TREND FOR THE INLAND VLYS FOR TUE
THROUGH THU. ACARS SOUNDINGS FM LAX TODAY SHOW A DECR IN THE BASE OF
THE MARINE INVERSION FM 1800 FT AT 16Z TO 1200 FT AT 20Z. THIS IS
CONSISTENT WITH THE EXPECTED LWRG AND STRENGTHENING OF THE MARINE
INVERSION AS WAS THE 00Z RAOB FM NKX SHOWING A DECR IN THE INVERSION
BASE FM 2000 FT SUN TO 1500 FT TODAY. THIS LWRG OF THE MARINE
INVERSION COMBINED WITH WK OFSHR PRESSURE GRADIENT TRENDS SHOULD BE
SUFFICIENT TO LIMIT STRATUS TONIGHT IN SWRN CA TO THE ORANGE COUNTY
CSTL PLAIN AND THE CST AND VLYS OF SAN COUNTY (I.E. ...NOT INTO THE
INLAND EMPIRE). HAVE UPDATED TO REMOVE LOW CLOUDS/FOG FM ZONES 48/49
THE NEXT TWO NIGHTS.
AS THE ALEUTIAN UPR TROUGH AMPLIFIES OVR THE NORTHEASTERN PAC AND
GULF OF AK TUE...AND PROGRESSES SLOWLY EASTWARD WED AND THU TOWARD
THE BRITISH COLUMBIA CST AND THE PAC NW STATES...THE CLOSED UPR LOW
TO THE SW OF SRN CA WL BE DRAWN NORTHEASTWARD TOWARD THE CA CST ON
WED. SLY FLOW BETWEEN THIS UPR LOW AND THE UPR RDG CNTRD E OF SRN CA
MAY BEGIN TO DRAW SOME MSTR NORTHWARD FM "GREG" INTO SRN CA ON WED.
WL LV CURRENT WORDING OF MOSTLY SUNNY FOR WED AS IS...BUT LATER
SHIFTS MAY WANT TO CONTINUE TO EVALUATE THE SUFFICIENCY OF THIS
WORDING DEPENDING UPON THE VERTICAL EXTENT AND AMOUNT OF TROPICAL
MSTR TO BE DRAWN NORTHWARD ACROSS SRN CA.
SAN 0000
.SAN...NONE.
MARTIN
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
AFDGRB 345 PM CDT MON SEP 6 1999
SFC HI OVER WISCONSIN AND RIDGE OVR PLAINS WL SHIFT E TONIGHT AND TUE AS
UPPER SYSTEM OVER NW US MOVES EAST. MODEL FORECASTS OF 100KT WINDS AT
300MB COMING ASHORE OVER WA/OR AT 18Z BACKED UP BY CURRENT ACARS DATA.
THE STRONG JET ENERGY COMING ASHORE IS SUPPOSED TO DIG A GOOD TROF OVER
GREAT LAKES BY END OF WEEK AND ALLOW COOL AIR OVER CANADA TO DROP SE
INTO U/S. UNTIL THEN...TONIGHT SHOULD BE CLEAR AND COOL. WITH 40S
DEWPOINTS IN MOST OF CWA IT SHOULD HAVE NO TROUBLE GETTING INTO THE
40S...WITH PERHAPS SOME UPPER 30S IN THE FAR NE AND SCATTERED FROST. WAA
BEGINS TUESDAY WITH 850MB TEMPS WARMING SEVERAL DEGREES. THIS SHOULD
PRODUCE MAX TEMPS SOMEWHERE NEAR MOS GUIDANCE. LEAD SHORTWAVE OF PACIFIC
NW ENERGY SHOULD PRODUCE A CHANCE OF PCPN TUESDAY EVENING...AS UPPER
SUPPORT TRIES TO SATURATE DRY LOW LEVEL AIR. DRIER...COOLER AIR COMES IN
WEDNESDAY AND KEEP GOING THROUGH THE WEEK. GUIDNACE TEMPS LOOK OKAY.
.GRB...NONE.
RDM
RDM
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