HAMweather.com Area Forecast Discussion for County Warning Area BUF

Thu, 16 Feb 2012 07:36:22 GMT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1142 PM EST WED FEB 15 2012

.SYNOPSIS...
HIGH PRESSURE CENTERED OVER PENNSYLVANIA WILL BRING SOME CLEARING TO 
THE AREA FOR AWHILE THIS EVENING AND EARLY TONIGHT. CLOUDS WILL 
RETURN DURING THE SECOND HALF OF THE NIGHT AS RAIN SPREADS NORTH OF 
AN AREA OF LOW PRESSURE THAT WILL BE MOVING OUT OF THE SOUTHERN 
PLAINS STATES. THE RAIN WILL SPREAD EAST ACROSS OUR AREA 
THURSDAY...THEN TAPER OFF THURSDAY NIGHT WHILE A CHANGEOVER TO SNOW 
TAKES PLACE. THE RAIN WILL BE ALSO ACCOMPANIED BY UNSEASONABLY MILD 
TEMPERATURES ON THURSDAY.

.NEAR TERM /THROUGH THURSDAY/...
THROUGH 1130 PM...SATELLITE IMAGERY SHOWS THAT SKIES HAVE CLEARED
ACROSS MOST OF WESTERN NEW YORK. THIS WILL BE SHORT LIVED...AS
MID AND HIGH CLOUDS HAVE ALREADY STARTED TO SPREAD INTO FAR
WESTERN NEW YORK. THIS CLEARING SHOULD ALLOW TEMPERATURES TO DROP
INTO THE 20S IN MOST LOCATIONS.

MOST RECENT MODEL RUNS...INCLUDING THE 12Z GFS/00Z HRRR/00Z NAM
ARE TRENDING A TAD FASTER WITH THE START OF PRECIPITATION. RADAR
TRENDS TEND TO SUPPORT THIS AS WELL. EXPECT PRECIPITATION TO ENTER
FAR WESTERN NEW YORK AROUND 09Z...REACHING BUFFALO AROUND
DAYBREAK...AND ROCHESTER BY MID-MORNING. THIS TIMING IS A COUPLE
HOURS FASTER THAN PREVIOUS GRIDS...REFLECTING ONLY A MODEST ADJUSTMENT.

THE BIGGER CONCERN IS HOW COLDER TEMPERATURES AND AN EARLIER START
TIME WILL IMPACT WHAT TYPE OF PRECIPITATION WILL FALL WHEN IT
STARTS EARLY THURSDAY MORNING. A LIGHT SOUTHEAST DOWNSLOPE AND
LATER START TIME WILL LIKELY RAISE SURFACE TEMPERATURES ABOVE
FREEZING NORTH OF I-90 FROM THE NY/PA LINE...TO BUF-ROC NORTHWARD.
AM A BIT MORE CONCERNED ABOUT INTERIOR SECTIONS...WHERE SURFACE
TEMPERATURES MAY STILL BE AT OR BELOW FREEZING. FORECAST SOUNDINGS
TREND TOWARD AN HOUR OR TWO OF SNOW/SLEET...BUT BEFORE
EVAPORATIONAL COOLING...THERE MAY BE ENOUGH OF A WARM LAYER ALOFT
FOR A VERY BRIEF PERIOD OF FREEZING RAIN RIGHT AT THE ONSET. MAIN
AREA OF CONCERN WOULD BE THE SOUTHERN TIER...AND HIGHER TERRAIN IN
SOUTHERN ERIE AND WYOMING COUNTIES. FROZEN PRECIPITATION WILL BE
BRIEF...AND LITTLE IF ANY ACCUMULATION IS EXPECTED. HOWEVER...IT
DOES NOT TAKE MUCH TO MAKE ROADS SLICK...THIS CONTINUES TO BEAR
WATCHING. DUE TO THE VERY BRIEF NATURE...DO NOT HAVE THE
CONFIDENCE TO ISSUE AN ADVISORY...BUT WILL ADD A MENTION TO THE
HWO TO RAISE AWARENESS FOR THE POSSIBILITY OF SLICK TRAVEL EARLY
THURSDAY MORNING.

SURFACE TEMPERATURES ARE LIKELY TO REMAIN BELOW FREEZING A LITTLE
LONGER EAST OF LAKE ONTARIO...BUT THE RAIN IS NOT EXPECTED TO
REACH THIS AREA UNTIL AFTER TEMPERATURES HAVE WARMED ABOVE
FREEZING. THE THERMAL PROFILES MAY STAY COLD ENOUGH FOR A MIX OF
RAIN AND SNOW ACROSS THE HIGHER ELEVATIONS OF LEWIS COUNTY.

LOW PRESSURE NEAR OKLAHOMA IS FORECAST TO TRACK TO THE NORTHEAST
OVERNIGHT AND REACH NORTHERN INDIANA BY 12Z THURSDAY. A MODEST LOW
LEVEL JET SURGING AHEAD OF THE LOW WILL ADVECT INCREASING LOW
LEVEL MOISTURE ACROSS THE OHIO VALLEY AND TOWARD THE LOWER LAKES
BY THURSDAY MORNING. IN TERMS OF QPF...AVERAGE BASIN RAINFALL
TOTALS ARE EXPECTED TO REMAIN UNDER 0.25 INCH THROUGH THURSDAY.

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
THE SURFACE LOW WILL BE IN THE PROCESS OF LIFTING ACROSS SOUTHERN 
ONTARIO/QUEBEC AT THE START OF THE PERIOD. COLDER AIR WORKING INTO 
THE REGION ON THE BACK SIDE OF THE LOW WILL BE TRANSITIONING 
PRECIPITATION OVER TO SNOW IN THE WEST...WHILE EASTERN SECTIONS 
SHOULD STILL BE RAIN. EASTERN SECTIONS SHOULD TRANSITION TO SNOW 
OVERNIGHT WITH SOME POTENTIAL FOR UPSLOPE ENHANCEMENT ALONG THE 
WESTERN SOUTHERN TIER AND TUG HILL. THE POTENTIAL FOR LAKE EFFECT 
SNOW SHOULD INCREASE FRIDAY NIGHT THROUGH SATURDAY AS A CLIPPER TYPE 
SHORTWAVE DROPS DOWN ACROSS THE LOWER LAKES. THIS WAVE WILL INCREASE 
THE MOISTURE DEPTH ALONG WITH OVER-LAKE INSTABILITY WITH 850 MB 
TEMPERATURES COOLING GRADUALLY TO AROUND -12C. BEST CHANCES FOR 
MINOR ACCUMULATING SNOWS WILL BE ALONG THE TUG HILL AND ACROSS THE 
HIGHER TERRAIN OF THE SOUTHERN TIER.

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
THE FORECAST FOR THE END PART OF THE WEEKEND WILL CENTER AROUND HOW 
THE SOUTHERN STREAM SYSTEM EVOLVES AS IT LIFTS OUT OF THE GULF 
COASTAL STATES. THERE STILL EXISTS QUITE A BIT OF MODEL SPREAD WITH 
HOW THIS SYSTEM WILL INTERACT WITH THE NORTHERN STREAM ENERGY. STILL 
A FEW MODEL RUNS OUT BEFORE THIS GETS BETTER RESOLVED. A COMPROMISE 
FORECAST FOR NOW SEEMS TO MOST REASONABLE WAY TO GO WITH A FORECAST 
TREND TO A MORE SOUTHERN SOLUTIONS MORE IN LINE WITH THE ECMWF. THIS 
MORE SOUTHERN SOLUTION WOULD KEEP NEARLY ALL INTERESTING WEATHER 
SOUTH OF THE AREA. ONCE THIS SYSTEM EXITS A BROAD RIDGE WILL DEVELOP 
ACROSS THE REGION FOR THE EARLY PART OF NEXT WEEK...PROVIDING A 
PERIOD OF FAIR WEATHER. NEXT SIGNIFICANT WAVE LOOKS TO CROSS THE 
REGION BY THE END OFF THE PERIOD.

.AVIATION /04Z THURSDAY THROUGH MONDAY/...
HIGH PRESSURE WILL BRIEFLY RIDGE ACROSS THE REGION...FOLLOWED BY
AN AREA OF WEAK LOW PRESSURE WHICH WILL TRACK TO THE WEST ACROSS
THE CENTRAL LAKES REGION. 

FOR THE 06Z TAFS...SITES WILL START OFF VFR...WITH THIS LIKELY TO
CONTINUE THROUGH 09Z.

AFTER THIS...PRECIPITATION WILL SPREAD FROM SW TO NE. NOT MUCH
CHANGE IN TIMING FROM PREVIOUS TAFS...AND MAINTAIN THINKING THAT
A SE FLOW AHEAD OF THE LOW SHOULD HELP KEEP CIGS UP AT BUF/IAG/ROC
UNTIL THE WIND SHIFT AS THE LOW PASSES. THEN EXPECT IFR/MVFR CIGS
WITH THE WIND SHIFT.

AT JHW...CIGS SHOULD LOWER QUICKER...WHERE DOWNSLOPING WILL NOT BE
AN ISSUE. THE LATER TIMING FOR ART SHOULD KEEP VFR CONDITIONS
THERE THE LONGEST.

THERE ARE A COUPLE ISSUES TO WATCH ON THURSDAY MORNING.
FIRST...WINDS ALOFT INCREASE TO 35 OR 40 KTS...RESULTING IN
MARGINAL WIND SHEAR. BASED ON FORECAST WIND PROFILES...HAVE ADDED
LLWS TO JHW ONLY...WITH SHEAR A BIT SHY OF CRITERIA AT OTHER
SITES. WILL ALSO HAVE TO WATCH FOR THE POSSIBILITY OF A BRIEF
PERIOD OF -FZRA OR PL AT JHW AT THE ONSET...DEPENDING ON HOW MUCH
TEMPERATURES DROP AHEAD OF THE RAIN.

FOR THURSDAY NIGHT...RAIN WILL END FROM WEST TO EAST...WITH
GRADUALLY IMPROVING CONDITIONS LIKELY DURING THE EVENING HOURS.

OUTLOOK...
THURSDAY NIGHT...MAINLY IFR IMPROVING TO MVFR.  
FRIDAY...MAINLY VFR WITH MVFR IN SNOW SHOWERS EAST OF LAKE ONTARIO.  
SATURDAY...MVFR IN OCNL -SHSN.
SUNDAY...MAINLY VFR.
MONDAY...VFR.

.MARINE...
HIGH PRESSURE OVER PA WILL SLIDE TO THE EAST COAST TONIGHT WHILE LOW 
PRESSURE MOVES OUT OF THE SOUTHERN PLAINS. THE CIRCULATION BETWEEN 
THESE TWO SYSTEMS WILL RESULT IN A SOUTHERLY FLOW ACROSS THE LAKES 
TONIGHT AND THURSDAY. THE WINDS MAY PICK UP ENOUGH TO PRODUCE SMALL 
CRAFT ADVISORY CONDITIONS ALONG THE FAR EASTERN NEARSHORES OF LAKE 
ONTARIO LATE IN THE DAY. AS THE LOW CONTINUES TO TRACK SOUTH OF 
JAMES BAY THURSDAY NIGHT AND FRIDAY...A WESTERLY FLOW OF COLDER AIR 
WILL FOLLOW...RESULTING IN A GOOD CHANCE FOR SMALL CRAFT ADVISORY 
CONDITIONS.

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.