May 4, 2012 Forecast Discussion

000
FXUS61 KALY 041443
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
1043 AM EDT FRI MAY 4 2012

.SYNOPSIS…
— Changed Discussion
A WARM FRONT WILL FINALLY MOVE EAST OF OUR REGION THROUGH THIS
AFTERNOON ONLY TO BE FOLLOWED BY A COLD BY LATE THIS AFTERNOON AND
THIS EVENING. THIS SCENARIO WILL KEEP OUR WEATHER SOMEWHAT
UNSETTLED THIS AFTERNOON AND EVENING WITH CHANCE FOR MORE SHOWERS
AND THUNDERSTORMS. BEHIND THE COLD FRONT…HIGH PRESSURE WILL
BUILD SOUTH FROM THE JAMES BAY REGION OF CANADA TO PROVIDE A DRY
WEEKEND WITH SEASONABLE AFTERNOON TEMPERATURES…BUT COOL NIGHTS.
— End Changed Discussion

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
— Changed Discussion
SATELLITE PICTURE TRENDS SHOW EXTENSIVE CLOUD COVER…BUT AS SOME
HEATING IS BEGINNING WEST OF OUR REGION…MORE CONVECTIVE TYPE
CLOUD COVER SEEN DEVELOPING. SO…SOME BREAKS IN THE CLOUDS SHOULD
OCCUR THIS AFTERNOON IN MANY AREAS…BUT STILL LIMIT SUNSHINE
ENOUGH THAT SOME AREAS MAY BE A COUPLE OF DEGREES SHORT OF 00Z MOS
VALUES. AREA SOUNDINGS SHOW RELATIVELY DEEP MOISTURE ALSO IMPLYING
QUITE A BIT OF CONVECTIVE CLOUD COVER…WITH TYPICAL NUMEROUS
BREAKS WITHIN THE CONVECTIVE CLUD COVER…AND LAPSE RATES NOT
VERY IMPRESSIVE. SOME ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS SHOULD DEVELOP…BUT THERE IS NOT MUCH OF A LOW
LEVEL FOCUS FOR ORGANIZED STORMS. STILL…JUST SOME ADJUSTMENTS TO
RAIN CHANCES… CLOUD COVER AND RAIN CHANCES THROUGH THIS
AFTERNOON.
— End Changed Discussion

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/…
ANY LINGERING SHOWERS AND THUNDERSTORMS THIS EVENING WILL END
QUICKLY AS MLCAPES DROP BELOW 100 J/KG BY 06Z SATURDAY…SHOWALTER
INDICES BECOME POSITIVE WITH A SECONDARY COLD FRONT MOVES THROUGH
THE REGION DURING THE EVENING. SINCE THE FRONTAL PASSAGE HAS
APPEARED TO BE HAVE SPED UP A LITTLE…WILL ONLY START WITH SLIGHT
POPS EARLY THIS EVENING…BEFORE DROPPING THEM AL TOGETHER.

LARGE HIGH PRESSURE WILL BUILD SOUTHEAST FROM THE HUDSON BAY REGION
OF CANADA SATURDAY AND NOSE INTO OUR REGION SATURDAY NIGHT AND
SUNDAY. THE SKY WILL CLEAR ON SATURDAY FROM NORTHWEST TO SOUTHEAST
AND NOW WE THINK ALL AREAS WILL BE DRY AS THE COLD FRONTS CONTINUES
TO SLIP WELL SOUTH OF OUR REGION. BY SATURDAY NIGHT EXPECT A MAINLY
CLEAR SKY TO PARTLY SKY WITH PLENTY OF SUNSHINE EXPECTED ON SUNDAY.

H850 TEMPERATURES LOOK TO COOL TO AROUND +2C NORTH TO +5C SOUTH
SATURDAY. THESE TEMPERATURES COUPLED WITH A GOOD DEAL OF MAY
SUNSHINE AND GOOD MIXING…WILL TRANSLATE TO AFTERNOON HIGHS RANGING
FROM AROUND 60 NORTH…UPPER 60S LOCALLY IN THE CAPITAL
DISTRICT…AND LOWER 70S TO THE LEE OF CATSKILLS…SOUTH/SOUTHEAST
OF ALBANY.

SATURDAY NIGHT THE WIND MIGHT DECOUPLE IN SHELTERED VALLEYS. THAT
WOULD ALLOW GOOD RADIATIONAL COOLING AND THE POSSIBILITY OF A FROST
OR EVEN FREEZE WELL NORTH OF ALBANY. THE GROWING SEASON WILL HAVE
STARTED ACROSS OUR ADIRONDACKS AND SOUTHERN GREENS. WE WILL HAVE
MONITOR THE SITUATION FOR THE POSSIBILITY OF AGRICULTURAL HEADLINES.
FOR NOW…WILL GENERICALLY MENTION THIS POSSIBILITY IN OUR HAZARDOUS
WEATHER OUTLOOKS.

THE REMAINDER OF THE REGION FROM THE CAPITAL DISTRICT SOUTH SHOULD
REMAIN SAFELY ABOVE FREEZING…BUT STILL BE CHILLY WITH LOWS IN THE
UPPER 30S AND LOWER 40S.

ON SUNDAY…AFTER THE CHILLY START…STRONG MAY SUNSHINE AND A
SLIGHT MODERATION THROUGH THE COLUMN SHOULD ALLOW HIGHS TO RETURN TO
SIMILAR LEVELS AS ON SATURDAY…ALTHOUGH THEY MIGHT ACTUALLY BE A
FEW POINTS WARMER IN OUR NORTHERN SECTIONS…WELL INTO THE 60S.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/…
DRY TO START SUNDAY NIGHT AND MONDAY AS THE LARGE SURFACE HIGH
PRESSURE SYSTEM SLOWLY SLIDES EAST AND OFF THE NEW ENGLAND COAST BY
MONDAY EVENING. MAINLY CLEAR SKIES DURING THIS PERIOD WITH LOWS
SUNDAY NIGHT IN THE 30S TO LOWER 40S…AND SOME UPPER 20S OVER THE
ADIRONDACK AND SOUTHERN GREEN MOUNTAINS. HIGHS MONDAY WILL BE IN
THE 60S TO LOWER 70S.

AS THE HIGH MOVES FURTHER OFFSHORE AND A FRONTAL BOUNDARY AND UPPER
LEVEL TROF SLOWLY MOVE EAST FROM GREAT LAKES…CLOUDS WILL INCREASE
MONDAY NIGHT ALONG WITH A CHANCE OF SHOWERS. THE FRONTAL BOUNDARY
AND UPPER LEVEL TROF WILL BE WITH US THROUGH THURSDAY AS THE FRONTAL
BOUNDARY SLOWS TO A CRAWL AND THE UPPER LEVEL TROF EVENTUALLY CUTS
OFF OVER THE EASTERN U.S.

GFS/ECMWF DISAGREE BY LATER IN THE WEEK…WITH THE GFS CUTTING OFF
THE UPPER LOW OVER THE NORTHEAST…WHILE THE ECMWF CUTS IT OFF OVER
THE SOUTHERN APPALACHIANS. THE MAIN EFFECT OF THESE DIFFERENCES IS
THAT THE ECMWF EVENTUALLY ENDS THE PCPN OVER THE REGION SOMETIME
LATE THURSDAY OR THURSDAY NIGHT…WHILE THE GFS KEEPS PCPN OVER THE
REGION THROUGH THE END OF THE WEEK. HOWEVER…FOR TUESDAY THROUGH
THURSDAY…THE DIFFERENT SCENARIOS DO NOT RESULT IN DIFFERENT
WEATHER FOR THE ALY FORECAST AREA. BOTH MODELS FORECAST MOSTLY
CLOUDY TO CLOUDY TUESDAY THROUGH THURSDAY WITH A GOOD CHANCE FOR
SHOWERS. HAVE GENERALLY FORECAST POPS BETWEEN 35 AND 50 PERCENT FOR
MOST OF THIS PERIOD.

TEMPERATURE WISE…LOWS MONDAY NIGHT WILL BE IN THE UPPER 30S AND
40S…AND GENERALLY IN THE 40S TUESDAY AND WEDNESDAY NIGHTS. HIGHS
TUESDAY THROUGH THURSDAY WILL BE IN THE 60S.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/…
WIDESPREAD IFR CIGS AND MVFR/IFR VSBYS AT KGFL/KALB AS LOTS OF LOW
LEVEL MOISTURE PERSISTS ACROSS THE REGION DUE TO THE SOUTHEAST FLOW
AND RAINFALL FROM LAST NIGHTS CONVECTION. AT KPOU THE CIG IS
OSCILATING BETWEEN SCT AND OVC. MAINLY IFR CIGS WILL PERSIST THROUGH
ABOUT 14Z TO 15Z…THEN TRANSITION TO MVFR AND EVENTUALLY TO VFR AS
A COLD FRONT MOVES THROUGH THIS AFTERNOON. AFTER 20Z EXPECT VFR
CONDITIONS AT ALL THREE TAF SITES AND CONDITIONS WILL REMAIN VFR
THROUGH THE REST OF THE TAF PERIOD ENDING AT 12Z SATURDAY.
CONVECTIVE POTENTIAL FOR LATER TODAY APPEARS TO HAVE DECREASED BASED
ON THE LATEST MODEL RUNS…SO HAVE ONLY INCLUDED VCSH IN THE TAF
FORECASTS FOR THIS AFTERNOON.

LIGHT SOUTH OR SOUTHEAST WINDS THROUGH AT KPOU AND KGFL THROUGH
ABOUT 15Z…AND 8 TO 10 KTS AT KALB WITH GUSTS OF 15 TO 20 KTS.
LATER THIS MORNING WINDS WILL SHIFT TO SOUTHWEST AT AROUND 10 KTS AS
THE TAF SITES BRIEFLY MOVE INTO A WARM SECTOR…BUT LATER TODAY
WINDS WILL SHIFT TO NORTHWEST AND NORTH AS A COLD FRONT MOVES SOUTH
ACROSS THE REGION. THE WIND SPEEDS WILL REMAIN AROUND 10 KTS AT
KGFL/KPOU AFTER THE FRONT MOVES THROUGH…BUT WIND GUSTS OF AROUND
20 KTS POSSIBLE AT KALB.

.OUTLOOK…
SAT…VFR. SLIGHT CHC -SHRA.
SAT NIGHT-MON…VFR…NO SIG WX.
TUE…MVFR/VFR. CHC -SHRA.

&&

.FIRE WEATHER…
IT STILL LOOKS AS OF MOST AREAS SHOULD RECEIVE A QUARTER INCH OR
MORE OF RAINFALL THROUGH THE AFTERNOON IN NUMEROUS
SHOWERS…BECOMING LESS NUMEROUS BY LATE IN THE DAY.

THEREAFTER…A DRYING TREND WILL BE UNDERWAY TONIGHT AS A COLD FRONT
WORKS THROUGH THE REGION SHIFTING THE WIND FROM THE SOUTH 5 TO 15
MPH TO WEST 10 TO 20 MPH.

RH VALUES WILL REMAIN ELEVATED THROUGHOUT THE DAY…ONLY DROPPING TO
THE AROUND 60 PERCENT. A NEARLY FULL RECOVERY TONIGHT WITH A
NORTHWEST WIND 5 TO 10 MPH.

DRY WEATHER IS EXPECTED SATURDAY THROUGH MONDAY WITH A GOOD DEAL OF
SUNSHINE…AND RH VALUES EXPECTED TO DROP TO 30 PERCENT OR LOWER
DURING EACH AFTERNOON.

&&

.HYDROLOGY…
NO HYDROLOGY PROBLEMS ARE LIKELY FOR THE NEXT FIVE DAYS.

SCATTERED TO NUMEROUS SHOWERS ARE STILL EXPECTED TO PROVIDE AN
AVERAGE BASIN RAINFALL OF A QUARTER TO HALF AN INCH ACROSS THE
REGION THROUGH TODAY. A FEW LOCALITIES COULD SEE CLOSER TO AN INCH
IN A THUNDERSTORM WITH HEAVIER RAIN…BUT THAT SHOULD BE THE
EXCEPTION RATHER THAN THE RULE.

THESE VALUES SHOULD NOT IMPACT RIVER AND MOST STREAMS AS THEY REMAIN
LOW AND NOW VEGETATION IS ALMOST FULLY ACTIVE.

AFTER TODAY…DRY WEATHER NOW LOOKS LIKELY THROUGH THE WEEKEND INTO
MONDAY. THE NEXT CHANCE OF SHOWERS WILL BE ON TUESDAY.

FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES…INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS…PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.

&&

.ALY WATCHES/WARNINGS/ADVISORIES…
CT…NONE.
NY…NONE.
MA…NONE.
VT…NONE.

&&

$$
SYNOPSIS…HWJIV/NAS
NEAR TERM…NAS
SHORT TERM…HWJIV
LONG TERM…GJM
AVIATION…GJM
FIRE WEATHER…HWJIV
HYDROLOGY…11

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