SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
AFDLOX 915 PM PDT SAT MAY 5 2001
A QUIET SATURDAY EVENING IS IN PROGRESS ACROSS THE FORECAST AREA.
MARINE INVERSION REMAINS SHALLOW ACROSS THE LA BASIN...WITH ACARS
SOUNDING OUT OF LAX EARLY THIS EVENING INDICATING A MARINE LAYER
DEPTH OF AROUND 700 TO 1000 FEET. LOW CLOUDS ARE A BIT MORE WIDESPREAD
THIS EVENING ACROSS THE INNER WATERS THAN HAS BEEN THE CASE THE
LAST COUPLE OF NIGHTS. CATALINA EDDY CONTINUES TO SPIN...AS
INDICATED BY PERSISTENT S WIND AT SAN AND SE WIND AT SAN PEDRO
CHANNEL. SFC DEWPOINTS HAVE INCREASED BY SEVERAL DEGREES ACROSS THE
COAST AND VALLEY AREAS OF SRN CA FROM 24 HOURS EARLIER...INDICATING
AN INCREASED MARINE INFLUENCE. GIVEN POSITION OF EDDY AND AMOUNT OF
CLOUDINESS ALREADY PRESENT ACROSS THE SRN INNER WATERS...ALONG WITH
ONSHORE PRESSURE GRADIENT TRENDS...WOULD EXPECT AREAS OF LOW CLOUDS
TO SPREAD INTO THE LA COUNTY COAST LATER TONIGHT AND CONTINUE INTO
SUNDAY MORNING. FURTHER NORTH...PATCHY CLOUDS WOULD BE EXPECTED
ALONG THE VTU/SBA S COASTS. BELIEVE MARINE LAYER WILL BE TOO SHALLOW TO
MAKE IT INTO THE VALLEYS. ALONG THE CENTRAL COAST...CLOUDS ALREADY
PRESENT NEAR PT CONCEPTION...WITH XVW OVC AND LPC BKNL. CURRENT FCST
OF AREAS LOW CLOUDS AND LOCALLY DENSE FOG DEVELOPING LOOKS GOOD.
INCOMING MODELS LOOK VERY SIMILAR TO PREVIOUS RUN...WITH UPPER
RIDGE BUILDING OVER CALIFORNIA ON SUNDAY AND HOLDING FIRM THROUGH
MONDAY. THIS WILL SQUASH THE MARINE LAYER AND CAUSE WARMING IN THE
LOWER LEVELS...WHICH WILL HEAT UP THE MAX TEMPS IN INLAND AREAS
BEGINNING TOMORROW AND ESPECIALLY MONDAY AND TUESDAY. CONTINUED WEAK
TO MODERATE ONSHORE FLOW WILL LIMIT THE EXTENT OF THE WARMING RIGHT
ALONG THE COAST HOWEVER. INLAND MAX TEMPS FOR SUNDAY MAY NEED TO BE
RAISED SOMEWHAT FROM THE CURRENTLY FORECAST VALUES...BUT WILL LET
THE MID SHIFT TAKE A LOOK AT THE 06Z MESO-ETA AND THE ETA-10 BEFORE
MAKING THIS DECISION. OTHERWISE CURRENT FORECAST LOOKS GOOD AND NO
UPDATES ARE PLANNED FOR THIS EVENING.
IN THE EXTENDED PERIODS...WARM TO HOT WEATHER WITH MINIMAL MARINE
INFLUENCE WILL CONTINUE TUE AS UPPER RIDGE SLOWLY SHIFTS EAST
ACROSS THE STATE. UPPER TROF MOVING INTO THE PAC NW WILL FLATTEN
THE RIDGE AND BRING COOLER TEMPS AND MORE MARINE INFLUENCE/LOW
CLOUDINESS TO THE REGION WED AND THU. A FLAT RIDGE IS FORECAST TO
BUILD ACROSS SRN CA ONCE AGAIN FRI INTO NEXT WEEKEND...ALLOWING
TEMPS TO WARM UP ONCE AGAIN. OVERALL THE UPCOMING WEEK SHOULD BE A
QUIET ONE WITH NORMAL TO ABOVE NORMAL TEMPS...NO EXTREMES OF WIND
AND DRY CONDITIONS.
LAX 0000. JACOBSON
.LAX...SMALL CRAFT ADVISORY (SEE LAXCWFLAX).
SOUTHWEST IDAHO/SOUTHEAST OREGON AREA FORECAST DISCUSSION...UPDATED
NWS BOISE IDAHO
AFDBOI 1100 AM MDT SAT MAY 5 2001
COLD FRONT HAS ALREADY MOVED THROUGH THE FORECAST AREA BUT UPPER
LEVEL TROF STILL OVER WASHINGTON/OREGON. NEW MODEL RUNS CONTINUE TO
PUSH THE UPPER LEVEL TROF THROUGH THE AREA TODAY WITH HIGH PRESSURE
TO BUILD OVER THE FORECAST AREA ON SUNDAY. CLOUDS SLOWLY DECREASING
BEHIND THE FRONT SO MORNING FORECAST LOOKS GOOD WITH DECREASING
CLOUDS TODAY. MAIN FORECAST PROBLEM FOR TODAY WILL BE THE WINDS.
FORECAST ALREADY HAS BREEZY AND WINDY AND THIS LOOKS GOOD. DRIER
OVER THE NEXT FEW DAYS WITH A WARMING TREND.
UPDATE: LATEST AIRCRAFT WINDS NEAR BOISE (BOI-DEN/BOI-SFO) AT 4900
FT INDICATE LOW LEVEL JET OF 25-35KTS WHICH IS SUPPORTED IN DOPPLER
WINDS 25-30KTS AT 5K'. RUC/OBS INDICATE H5/H7 SPEED MAX PUSHING IN
BY 6PM WITH SFC PRES GRADIENT INCREASING BETWEEN NOON-6PM. SO WE
UPDATED CURRENT ZONES AND WENT WITH ADVY FOR WRN MAGIC VLY AND CAMAS
PRAIRE. ALLEN ET. AL.
.BOI...WIND ADVISORY 16/28 UNTIL SUNSET/9 PM.
AREA FORECAST DISCUSSION
NWS CHICAGO IL
AFDCHI 315 AM CDT SUN MAY 6 2001
THE UPPER AIR CIRCULATIONS APPEARS TO BE IN CENTRAL NEBRASKA AS SEEN
WITH THE PROFILER 500 MB PLOTS AND WATER VAPOR LOOPS. 850 MB SHOWS
WARM ADVECTION AND ADVECTION OF LOW LEVEL MOISTURE INTO NORTHEAST
ILLINOIS AND NORTHWEST INDIANA AT 0000 UTC. COMPARING THE SOUNDING
AT 0000 UTC AT ILX AND THE ACARS SOUNDING AT ORD THE AIR LOOKS TO BE
MORE STABLE NEAR CHICAGO AND LAKE MICHIGAN. WILL KEEP WIDELY
SCATTERED SHOWERS IN THE FORECAST FOR THIS MORNING.
THE 500 MB LOW WILL SLOWLY MOVE EAST. A SHORT WAVE AS SEEN ON THE
700 TO 300 MB LAYER VORTICITY WILL MOVE THROUGH THIS MORNING. THEN
OVERNIGHT ANOTHER WAVE MOVES THROUGH. THIS WAVE APPEARS STRONGER AND
FROM FORECAST LI THE AIR IS MUCH LESS STABLE. MONDAY THE COLD AIR
ARRIVES IN A FRONT AND TUESDAY THE UPPER AIR LONG WAVE MOVE OVER
WITH MORE POSITIVE VORTICITY ADVECTION.
WILL USE THE AVN MODEL AND AVN MOS AS GUIDANCE.
.CHI...NONE
$$
WHW