011 FXUS61 KBGM 211438 AFDBGM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 1038 AM EDT SAT SEP 21 2013 .SYNOPSIS... A COLD FRONT WILL SWEEP ACROSS THE AREA THIS AFTERNOON THROUGH EVENING...BRINGING A PERIOD OF RAIN TO CENTRAL NEW YORK AND NORTHEAST PENNSYLVANIA. IN THE WAKE OF THE FRONT...OUR WEATHER WILL BE MUCH COOLER SUNDAY WITH A FEW LINGERING SHOWERS...MAINLY IN CENTRAL NEW YORK. DRY CANADIAN HIGH PRESSURE WILL THEN TAKE CHARGE MONDAY...AND KEEP OUR WEATHER DRY FOR SEVERAL DAYS WITH GRADUALLY WARMING TEMPERATURES. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 1035 AM UPDATE... HV UPDATED THE GRIDS TWICE THIS MRNG TO DELAY ARRIVAL OF PCPN AS IT CONTS TO SLOW DOWN AND MAY HV TO CONTINUALLY UPDATE FM HERE ON OUT. VRY IMPRESSIVE 12Z RAOB OUT OF KBUF WITH COMPLETE SATURATION FM THE SFC UP TO 400MB. ON THE FLIP SIDE KALY IS ONLY SATURATED FM THE SFC TO 950MB. STILL A LOT OF SIGNIFICANT DRY AIR TO OVERCOME BFR IT STARTS RAINING HERE. LARGE PLUME OF PW VALUES EXTENDING UP INTO AREA FM THE GULF COAST AND EXPECT THIS WL SET THE STAGE FOR LOCALLY HVY RAINFALL ONCE THE PCPN STARTS, COURTESY OF LLJ INCRSG MOISTURE THROUGHOUT THE CWA TDA. THIS WL COMBINE WITH STRONG DIVERGENCE ASSOC WITH RIGHT ENTRANCE REGION OF H25 JET STREAK AS IT SLOWLY WORKS ITS WAY EAST IN HIGHLY AMPLIFIED FLOW. HV DELAYED RAIN FM MVG INTO WRN ZONES UNTIL CLOSER TO NOON AND THEN SLOWLY HEADING EAST FM THERE. CURRENT THINKING IS THAT RAIN WL NOT EVEN BEGIN IN THE I-81 CORRIDOR UNTIL AFT 18Z THIS AFTN AND CONTINUE UNTIL MIDNIGHT. WHEN ALL IS SAID AND DONE WITH PW VALUES OF ARND 1.8 INCHES (200% ABV NORMAL) AVG QPF AMNTS WILL BE ARND 1 INCH WITH LOCALLY HGR AMNTS OF UP TO 2 INCHES POSSIBLE. GIVEN THIS SCENARIO, HV LWRD MAX TEMPS EVERYWHERE BY 2-4 DEGREES. PREV DISCUSSION BLO... 4 AM UPDATE...SHARP UPPER LEVEL TROUGH TO OUR WEST WITH AN APPROACHING COLD FRONT. FRONT HAS BEEN SLOWING DOWN SOME AND WITH IT THE ADVANCEMENT OF RAIN. SOUTHERLY WINDS AHEAD OF THE FRONT ALONG WITH SOME HIGH CLOUDS ARE HOLDING TEMPERATURES WARMER OVERNIGHT AND WITH A WARMER START HIGH TEMPS FOR THE DAY HAVE BEEN BUMPED UP SOME ALONG WITH A LITTLE DOWNSLOPE IN THE LAKE PLAIN. ALSO BUMPED UP WIND AND WIND GUSTS FOR TODAY AND SLOWED DOWN THE TIMING OF THE RAIN MOVING IN. RAIN LOOKS LIKE IT WILL MOVE INTO THE WESTERN PORTION OF THE CWA BETWEEN 15 AND 18Z AND AREAS EAST OF I-81 BETWEEN 18 AND 21Z. WHILE THE RAIN INTENSITY WILL VARY THERE IS A CHANCE FOR PERIODS OF HEAVY RAIN AS A SHORT WAVE TRACKS NEWD ALONG THE FRONT. MODELS HAVE BACK OFF JUST A TAD ON FORECASTED PWAT VALUES IN THE 1.35-1.65 RANGE. POTENTIAL RAINFALL AMOUNTS OF AN 1.0-1.5 INCHES WITH LOCALLY HIGHER AMOUNTS POSSIBLE. THIS WOULD BRING RISES ON THE RIVERS BUT RIVER FLOODING IS NOT EXPECTED. WE ARE NOT EXPECTING TSTMS, BUT CAN NOT TOTALLY RULE IT OUT. CHANCES ARE ABOUT 10 PERCENT OR LESS FOR EMBEDDED THUNDER AS THE FRONT MOVES THROUGH THIS AFTERNOON. IF THERE IS ANY EMBEDDED CONVECTION...THEN A QUICK BURST OF HEAVY RAIN COULD CAUSE QUICK RISES ON LOCAL SMALL STREAMS AND POOR DRAINAGE AREAS. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... COLD FRONT MOVES EAST OF THE AREA SAT NIGHT WITH THE UPPER TROUGH MOVING ACROSS THE AREA SUNDAY. CYCLONIC FLOW ALOFT AND UPSLOPE NW FLOW OFF THE LAKES AT THE SURFACE BRINGS THE TYPICAL STRATOCU AND CHANCE OF A LIGHT SHOWER ESPECIALLY OVER SOME OF THE HIGHER TERRAIN IN CENTRAL NY. CANADIAN HIGH PRES BUILDS IN WITH FAIR AND DRY WEATHER SUNDAY NIGHT THROUGH MONDAY NIGHT. PATCHY FROST CAN'T BE RULE OUT SUNDAY NGT ACRS NORMALLY COLDER VLY REGIONS OF THE TWIN TIERS AND CATSKILLS AND MORNING FOG ALONG THE RIVER VALLEYS IS POSSIBLE. && .LONG TERM /TUESDAY THROUGH FRIDAY/... 3 AM UPDATE... GRIDS ADJUSTED TO ACCOUNT FOR LATEST MODELS AND WPC GUIDANCE. LITTLE CHANGE...THOUGH SOME WARMING TO OCCUR BY THU-FRI WITH STRONGER UPPER RIDGING. LOOKING DRY AND QUIET THROUGH THE PERIOD COURTESY OF LARGE AND PERSISTENT SURFACE HIGH PRESSURE. NEXT RAIN CHANCE WAITS UNTIL SOMETIME NEXT WEEKEND...WHEN GFS AND ECMWF /THOUGH DIFFERING BY ABOUT 12 HOURS ON TIMING/ AGREE THAT OUR NEXT COLD FRONT WILL SWEEP THROUGH THE REGION. PREVIOUS DISCUSSION... H5 LOW WL BE LOCATED ACRS THE GULF OF MAINE BY THE BEGINNING OF THE LONG TERM PD WITH H5 RIDGE BUILDING IN PER ALL MED RANGE MODELS. 576DM RIDGE BUILDS IN ON TUESDAY WITH OMEGA BLOCK SETTING UP THRU THE RMNDR OF THE EXTNDD. PRTLY-MSTLY SUNNY SKIES EXPECTED FOR THE NEXT WEEK WITH HIGH TEMPS ARND 70F AND LOWS ARND 40/LWR 40S. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... 12Z UPDATE... MOISTENING SOUTHERLY LOW LEVEL FLOW IS BRINGING FUEL ALTERNATE MVFR CIGS INTO SOME TERMINALS EARLY THIS MORNING...AS WELL AS MARGINAL LLWS CONDITIONS FOR TERMINALS WHERE WINDS ARE NOT YET MIXING DOWN. BEYOND 14-15Z...GUSTS AT LEAST IN THE 18-22 KT RANGE SHOULD BEGIN TO BE REALIZED FOR ALL TERMINALS...NULLIFYING MARGINAL LLWS CONDITIONS. LINE OF MODERATE TO HEAVY SHOWERS SET TO CONGEAL ALONG COLD FRONT...SWEEPING ACROSS THE AREA WITH TIMING ROUGHLY FROM 20Z WEST TO 04Z EAST. GIVEN THE FAIRLY HIGH CONFIDENCE IN THIS SCENARIO...TEMPO GROUPS ARE ALREADY INSERTED IN THE TAFS WITH POTENTIAL FOR IFR VIS AND/OR CIG ALONG WITH VEERING IN WIND DIRECTION WITHIN THE HEAVIER PORTION OF THE LINE. EMBEDDED THUNDER NOT OUT OF THE QUESTION...BUT OVERALL INSTABILITY LACKING AND THUS WILL BE THE EXCEPTION AND NOT THE RULE. AFTER THE MAIN RAIN BAND...NORTHWESTERLY WINDS WILL BE FAVORABLE FOR KBGM AND KITH TO HANG ON TO IFR CONDITIONS VIA MOIST UPSLOPE CAUSING A LOW CIG LATER THIS EVENING. MOIST LOW LEVELS MAY ALSO CAUSE KRME TO PERSIST AT IFR FOR AWHILE AS WELL. COLD AIR MOVING IN MAY ALLOW SOME DRIER AIR TO ATTEMPT TO MIX DOWN DURING THE PREDAWN HOURS SUNDAY MORNING...BUT MVFR CIG AND IN SOME CASES IFR /ESPECIALLY KBGM/ WILL BE STUBBORN TO END UNTIL BETTER MIXING WITH THE LIGHT OF DAY SUNDAY. OUTLOOK... SUNDAY...MVFR CIGS ESPECIALLY CNY TERMINALS...BECOMING VFR. SUN NGT TO WED...MAINLY VFR. LATE NIGHT/EARLY MORNING VALLEY FOG POSSIBLE ESPECIALLY KELM. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...BMW/MDP NEAR TERM...BMW/PVN SHORT TERM...BMW LONG TERM...MDP/PVN AVIATION...MDP