Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA

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000
FXUS66 KMTR 140400
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
900 PM PDT SUN JUL 13 2014

.SYNOPSIS...HIGH PRESSURE WILL KEEP INLAND TEMPERATURES ABOVE
AVERAGE THROUGH MONDAY...BUT COASTAL AREAS WILL REMAIN NEAR
SEASONAL NORMS. MONSOONAL MOISTURE MONDAY AND TUESDAY WILL BRING
MID LEVEL CLOUDS UP FROM THE SOUTH.

&&

.DISCUSSION...AS OF 9:00 PM PDT SUNDAY...AN UPPER RIDGE CENTERED
OVER NEVADA CONTINUED TO STRENGTHEN ACROSS CALIFORNIA
TODAY...WARMING THE AIRMASS ALOFT BY A FEW DEGREES. THE MARINE
LAYER WAS COMPRESSED TO A DEPTH OF ONLY ABOUT 1000 FEET BY LATE IN
THE DAY. THESE DEVELOPMENTS...PLUS WEAKER ONSHORE FLOW AS THE N-S
SURFACE PRESSURE GRADIENT STRENGTHENED...RESULTED IN SIGNIFICANT
WARMING IN THE HILLS AND INLAND VALLEYS TODAY. HIGH TEMPERATURES
IN THESE AREAS TODAY WERE 10 TO 15 DEGREES WARMER THAN YESTERDAY.

LOW CLOUDS CLEARED FROM NEARLY THE ENTIRE COAST BY EARLY EVENING
AND ONLY SCATTERED HIGH CLOUDS REMAIN. GIVEN THE CURRENT ROBUST
NORTHERLY GRADIENT (CURRENTLY 8 MB FROM ACV TO SFO) AND SHALLOW
MARINE LAYER...IT`S LIKELY THAT ONLY PATCHY LOW CLOUDS AND FOG
WILL REDEVELOP OVERNIGHT...AND THEN MOSTLY REMAIN CONFINED TO THE
IMMEDIATE COAST.

TEMPERATURES ARE EXPECTED TO CONTINUE TRENDING HIGHER ON MONDAY.
ONSHORE FLOW IS FORECAST TO BEGIN TO INCREASE BY LATE AFTERNOON...BUT
LACK OF MORNING LOW CLOUD COVER AND A DRIER AIRMASS IN THE LOW
LEVELS SHOULD ALLOW TEMPERATURES TO PEAK ABOVE TODAY`S LEVELS BY
EARLY AFTERNOON. INCREASING MID/UPPER LEVEL CLOUD COVER ASSOCIATED
WITH AN INFLUX OF MONSOONAL MOISTURE MAY ACT TO INHIBIT WARMING A
BIT...BUT THESE HIGHER CLOUDS PROBABLY WON`T BE THICK ENOUGH TO
HAVE A MAJOR IMPACT ON TEMPS.

THE UPPER RIDGE CENTERED TO OUR EAST HAS LIFTED SLIGHTLY TO THE
NORTH AND THE RESULTING SOUTHEASTERLY FLOW ALOFT IS BEGINNING TO
ADVECT MONSOONAL MOISTURE INTO CENTRAL AND SOUTHERN CA. THE
SCATTERED HIGH CLOUDS PROVIDING OUR AREA WITH A BEAUTIFUL SUNSET
THIS EVENING ARE THE LEADING EDGE OF THIS MOISTURE WHICH IS
FORECAST TO INCREASE FROM SOUTH TO NORTH TONIGHT THROUGH MONDAY
NIGHT. THE 00Z NAM SHOWS LESS IN THE WAY OF MID-LEVEL INSTABILITY
OVER OUR ARE THAN WHAT WAS FORECAST BY YESTERDAY`S MODEL RUN.
IN ADDITION...THE MODELS GENERALLY AGREE THAT THE MOST SIGNIFICANT
MOISTURE AND INSTABILITY WILL SURGE NORTHWESTWARD OFFSHORE.
THEREFORE...THE CHANCE OF ELEVATED CONVECTION OVER OUR AREA FROM
MONDAY THROUGH TUESDAY APPEARS VERY SMALL AND NOT WORTH MENTIONING
IN THE FORECAST. MID AND HIGH LEVEL CLOUDS THROUGH MIDWEEK IS
PROBABLY THE MOST OUR AREA WILL SEE OUT OF THIS MOISTURE INFLUX.

INCREASED MID AND HIGH LEVEL MOISTURE WILL HOLD TEMPERATURES UP AT
NIGHT...ESPECIALLY ON MONDAY NIGHT AND TUESDAY NIGHT. LOW
TEMPERATURES...WHICH ARE TYPICALLY IN THE 50S AT MOST LOWER
ELEVATION LOCATIONS THIS TIME OF YEAR...WILL PROBABLY BE IN THE
60S INSTEAD.

THE UPPER RIDGE WILL WEAKEN ACROSS OUR AREA FROM TUESDAY THROUGH
THURSDAY AS THE RIDGE AXIS CONTINUES TO SLOWLY SHIFT NORTH. THIS
WILL RESULT IN A DEEPER MARINE LAYER AFTER MONDAY. AT THE SAME
TIME...A SOUTHERLY LOW LEVEL FLOW WILL HELP ADVECT COOLER MARINE
AIR INLAND. THUS...WE CAN EXPECT A SIGNIFICANT COOLING TREND
ACROSS INLAND AREAS FROM TUESDAY THROUGH THURSDAY. INLAND TEMPS
WILL LIKELY DROP TO NORMAL...OR EVEN SLIGHTLY BELOW NORMAL...BY
MIDWEEK. DRIER AIR ALOFT WILL MOVE IN FROM THE SOUTHWEST BEGINNING
AROUND MIDWEEK AND SHOULD CLEAR OUT MID AND HIGH LEVEL CLOUDS BY
THURSDAY.

&&

.AVIATION...AS OF 6:30 PM PDT SUNDAY...STRONG N-S GRADIENTS HAVE
DEVELOPED WITH SFO-ACV OVER 6 MB. THIS WILL KEEP STRATUS OUT OF
THE SFO BAY AREA THROUGH THE AIRPORT EVENING RUSH. THE STRONG N-S
GRADIENT WILL PREVENT STRATUS AT THE COAST FROM SPREADING INLAND
BUT PATCHY LOW CLOUDS ARE LIKELY TO FORM WITHIN AROUND SFO BAY.
THEREFORE THERE IS ONLY A LOW POSSIBILITY FOR CIGS MAKING AN
IMPACT OVERNIGHT.

VICINITY OF KSFO...VFR. WEST WINDS TO 20 KT THROUGH 04Z.

KSFO BRIDGE APPROACH...PATCHY CIGS MAY POSSIBLY DRIFT IN AND OUT
OF THE APPROACH 12Z-16Z.

MONTEREY BAY AREA TERMINALS...CIGS ARE CLEARING OUT OF MRY BAY.
CIGS RETURNING AFTER 06Z. CONFIDENCE IS LOW AS CIGS COULD COME IN
LATER THAN FORECAST.

&&

.MARINE...AS OF 5:00 PM PDT SUNDAY...HIGH PRESSURE WILL
STRENGTHEN OFF THE WEST COAST TODAY AND TONIGHT RESULTING IN
INCREASING NORTHWEST WINDS. THE WINDS WILL DECREASE LATE MONDAY
AND TUESDAY AS THERMAL TROUGH DEVELOPS ALONG THE COAST.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 3 AM
             SCA...PT ARENA TO PT REYES 10-60 NM
             SCA...PT REYES TO PIGEON PT 10-60 NM
             SCA...PT REYES TO PIGEON PT 0-10 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
             SCA...PIGEON PT TO PT PINOS 10-60 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM
             SCA...PT ARENA TO PT REYES 0-10 NM


&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION: W PI
MARINE: SIMS

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