Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 210559
AFDBGM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BINGHAMTON NY
159 AM EDT TUE APR 21 2015

.SYNOPSIS...
A COLD FRONT WILL FINISH CROSSING THE REGION OVERNIGHT...BRINGING
AN END TO THE SHOWERS AND THUNDERSTORMS. THE REMAINDER OF THE
WEEK WILL BE UNSETTLED AND COOL WITH SCATTERED RAIN SHOWERS WHICH
COULD MIX WITH WET SNOW SHOWERS DURING THE OVERNIGHT PERIODS. SNOW
ACCUMULATION IS NOT EXPECTED.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
11 PM UPDATE...
LACKAWANNA-LUZERNE-PIKE IS ALL THAT IS LEFT OF SEVERE TSTORM WATCH
NUMBER 92. ELEVATED MIXED LAYER ADVECTED IN THIS EVENING WHICH
STEEPENED MID LEVEL LAPSE RATES. WE HAVE HAD MANY REPORTS OF SMALL
HAIL...IN SOME CASES A LOT OF IT...AND YET NO LARGE HAIL. WIND
REPORTS HAVE BEEN SCANT. PENN YAN REACHED 34 KTS. THE RELATIVELY
COOL AIR WITH SOUTHEAST FLOW NEAR THE SURFACE LIKELY PREVENTED
HIGHER GUSTS FROM MIXING DOWN FOR MOST OF THE AREA. THINGS WILL
CONTINUE TO WIND DOWN THE NEXT FEW HOURS.

815 PM UPDATE...
SEVERE TSTORM WATCH ISSUED FOR SOUTHWEST TO CENTRAL OF THE
AREA...FROM CAYUGA-CORTLAND-BROOME-WAYNE-PIKE COUNTIES WESTWARD.
UP TO NOW INSTABILITY HAS BEEN LACKING DUE TO STABLE ESE FLOW
AHEAD OF THE APPROACHING FRONT...HOWEVER...WARM SECTOR IS MANAGING
TO SNEAK IN JUST AHEAD WITH DEWPOINTS NOW BUMPING INTO THE LOW-MID
50S. GOOD AMOUNT OF SHEAR BUT MIXED LAYER CAPE OF ONLY A FEW
HUNDRED J/KG. NARROW AXIS OF CONVECTION IS NOW ENHANCING. MAIN
THREAT IS SMALL CLUSTERS OF THUNDERSTORMS WITH HAIL AND LOCALLY
DAMAGING WINDS. SHEAR WILL CONTRIBUTE TO THIS BY ALLOWING FOR A
FEW ROTATING MESOCYCLONES. WE WILL HAVE TO WATCH CLOSELY FOR SIGNS
OF ROTATION CONSIDERING THE SHEARED ENVIRONMENT.

PREVIOUS DISCUSSION...
SHOWERS AND THUNDERSTORMS ARE MOVING INTO WESTERN NYS ATTM AS THE
UPPER LEVEL TROF BEGINS MOVING INTO THE REGION. MID LEVEL SHORT
WAVE AND SOME SFC BASED INSTABILITY IN ENHANCING THE ACTIVITY.
THIS AREA OF CONVECTION WILL PASS THROUGH THE REGION PRIMARILY
THIS EVENING. STRONG ENVIRONMENTAL WINDS AND LOW LEVEL HELICITY
WOULD BE SUPPORTIVE FOR MORE SIGNIFICANT CONVECTIVE DEVELOPMENT.
THE PRIMARY THREAT WOULD BE STRONG DAMAGING WINDS ALTHOUGH SFC
BASED CAPE IS A LIMITING FACTORS. EVEN LATER TONIGHT STEEP MID
LEVEL LAPSE RATES COULD KEEP THUNDERSTORMS OVER THE AREA THROUGH
MIDNIGHT. SFC OCCLUSION WILL CROSS THE REGION LATE TONIGHT
THEREFORE SHOWERS WILL PERSIST OVER THE REGION INTO THE LATE NIGHT
PERIOD BUT SIGNIFICANT CONVECTION AT THIS TIME IS UNLIKELY.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/...
UPPER LEVEL LOW WILL SLOWLY TRACK FROM SOUTHERN ONTARIO TO NRN NYS
BY THURSDAY. THIS FEATURE WILL PROVIDE UNSETTLED WEATHER WITH
LOWERING TEMPS THROUGH THE PERIOD. WILL CONTINUE TO ADVERTISE
CHC/SLIGHT CHC POPS FOR RAIN SHOWERS WITH THE EXCEPTION OF LIKELY
POPS ON WED ACROSS NYS AS A SFC TROF DROPS THROUGH. THE BOUNDARY
LAYER WILL BE COLD ENOUGH DURING THE NIGHTTIME PERIODS FOR A MIX
OF RAIN AND SNOW SHOWERS. SNOW ACCUM IS NOT EXPECTED AT THIS TIME
ALTHOUGH IN THE HIGHEST ELEVATIONS A COATING MAY OCCUR. BY WED
NIGHT LOWS WILL BE IN THE 30S WITH HIGHS THURSDAY IN THE LOWER TO
MIDDLE 40S.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
THE LONG RANGE PERIOD STARTS OUT WITH UPPER LEVEL LOW PRESSURE
OVER EASTERN CANADA AND DEEP NORTHWESTERLY FLOW ACROSS THE
NORTHEAST U.S. SOME DIFFERENCES ARE SEEN BETWEEN THE ECMWF AND GFS
STARTING AS EARLY AS THE SATURDAY... WITH THE ECMWF SHOWING THE
UPPER LOW SHIFTING EASTWARD IN RESPONSE TO A SYSTEM PROGRESSING
EAST ACROSS THE CENTRAL PLAINS. MEANWHILE THE GFS IS NOT
PROGRESSIVE AT ALL SHOWING UPPER LEVEL LOW PRESSURE ANCHORED OVER
QUEBEC THROUGH THE PERIOD. THE ECMWF FORECAST WOULD NOT BE QUITE
AS COOL AS THE GFS ALTHOUGH BOTH MODELS WOULD INDICATE BELOW
NORMAL TEMPERATURES. THE GFS FORECAST WOULD BE COLD ENOUGH FOR
SCATTERED RAIN AND SNOW SHOWERS FRIDAY THROUGH SUNDAY WHILE THE
ECMWF WOULD BE MAINLY DRY THROUGH THE PERIOD. AT THIS TIME DO NOT
SEE ENOUGH MODEL CONSENSUS TO SUPPORT ANY REAL CHANGES TO OUR
ONGOING FORECAST... AND HAVE KEPT MAINLY 20-40 POPS THROUGH THE
PERIOD WITH TEMPERATURES WELL BELOW NORMAL... SCATTERED RAIN
SHOWERS DURING THE AFTERNOON AND EVENING HOURS AND SCATTERED RAIN
AND SNOW SHOWERS DURING THE OVERNIGHT THROUGH EARLY MORNING HOURS.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
SHOWERS AHEAD OF AN ADVANCING COLD FRONT ARE STILL PUSHING EAST
OVER CENTRAL NY AND NORTHEAST PA AND LIGHTNING ACTIVITY HAVE
STARTED TO DIMINISH. FOR THE MOST PART... SHOWERS ARE VFR WITH
MVFR VISBYS. EXPECT A FEW HOURS OF MVFR CIGS OVER KITH... KELM...
AND KBGM UNTIL THE FRONT PASSES THROUGH. RAIN SHOWERS ARE EXPECTED
TO LINGER BEHIND THE FROPA THROUGH THE EARLY MORNING HOURS...
THEN A BREAK IN ACTIVITY IS EXPECTED DURING THE EARLY AFTERNOON.
RAIN SHOWERS WITH POSSIBLE THUNDER ARE EXPECTED TO DEVELOP DURING
THE AFTERNOON HOURS AS THE ATMOSPHERE BECOMES UNSTABLE AGAIN.
DECIDED TO NOT MENTION TSRA IN TAF ATTM AS CONFIDENCE IS NOT THERE
ON TIMING.

WINDS WILL INCREASE SHORTLY AFTER 14Z THIS MORNING AND ARE
EXPECTED TO BE WESTERLY AND BREEZY THROUGH SUNSET. WINDS WILL
THEN BECOME LIGHT AND SOUTHERLY.

.OUTLOOK...

TUE NIGHT-SAT...UNSETTLED PATTERN. RESTRICTIONS IN -SHRA, LOW
CLOUDS...ESP MON NGT.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.

&&

$$
SYNOPSIS...MDP/RRM
NEAR TERM...MDP/RRM
SHORT TERM...RRM
LONG TERM...MSE
AVIATION...KAH


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