031 FXUS61 KALY 271450 AFDALY AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 1050 AM EDT THU MAY 27 2010 .SYNOPSIS... A BACK DOOR COLD FRONT WILL CONTINUE TO SLOWLY DRIFT SOUTHWESTWARD ACROSS THE AREA THIS AFTERNOON...PROVIDING THE FOCUS FOR ADDITIONAL SHOWERS AND THUNDERSTORMS. SOME STORMS MAY BECOME SEVERE... ESPECIALLY FROM THE CAPITAL REGION WESTWARD. THE COLD FRONT WILL PUSH THROUGH THE AREA BY TONIGHT...USHERING IN COOLER AND MAINLY DRY WEATHER FOR FRIDAY. A WEAK COLD FRONT APPROACHING FROM THE GREAT LAKES MAY BRING ISOLATED TO SCATTERED SHOWERS ON SATURDAY....WITH DRY AND WARMER CONDITIONS EXPECTED FOR SUNDAY. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... CLOUD COVER ON SATELLITE IMAGERY SHOWING THE GEENRAL POSITION OF THE SIDE DOOR FRONT...AND SUSPECT A DECENT TEMPERATURE GRADIENT WILL SET UP THIS AFTERNOON...BETTER DEFINING THE SURFACE BOUNDARY. THE DEW POINT AND TEMPERATURES BOUNDARIES MAY BE A LITTLE DISPLACED FROM EACH OTHER...BUT BASED ON CURRENT CONVECTION IN CANADA...HEADED SOUTH...THIS CONVECTION WILL TRACK THROUGH WESTERN AND CENTRAL PARTS OF THE FORECAST ARWA THIS AFTERNOON AND EVENING...WITH POTENTIAL SCATTERED SEVERE WINDS AND HAIL. VIL OF THE DAY FOR 1" HAIL SHOULD BE IN THE LOWER TO MID 50S...BUT WILL ADJUST BASED ON ANY REAL TIME REPORTS AS THEY COME IN THIS AFTERNOON AND EVENING. AREA 12Z SOUNDIGS SHOW THE REGION NOT AS UNSTABLE AS YESTERDAY AND LAST NIGHT...BUT STILL DECENTLY UNSTABLE...ESPECIALLY AS YOU HEAD INTO CENTRAL AND WESTERN NY. SO...WILL KEEP AN EYE ON POTENTIAL SEVERE WEATHER POTENTIAL/EVOLUTION...AND JUST SOME MINOR ADJUSTMENTS TO TEMPERATURES AND SKY COVER. PREV AFD BELOW... AS OF 415 AM...MAIN CONCERN FOR TODAY WILL BE THE POTENTIAL FOR SEVERE THUNDERSTORMS AHEAD OF AND ALONG A BACK DOOR COLD FRONT THAT WILL BE GRADUALLY MOVING SOUTHWESTWARD THROUGH THE AREA. AS OF 08Z...THE SURFACE FRONT HAS PUSHED INTO WESTERN NEW ENGLAND ZONES...SO IT SEEMS THIS AREA WILL BE SPARED FORM SEVERE WEATHER TODAY. HOWEVER...FARTHER TO THE WEST THERE WILL STILL BE SIGNIFICANT INSTABILITY BUILDUP BY THIS AFTERNOON IN WARM/MOIST ENVIRONMENT. SBCAPE VALUES OF 1000-2500 J/KG ARE FORECAST WITH THE HIGHEST VALUES ACROSS THE CATSKILL MOUNTAINS. THERE LOOKS TO BE A SHARP GRADIENT TO THE HIGH CAPE...WITH AREAS BEHIND THE FRONT TO THE NORTH AND EAST MUCH MORE STABLE. BEST CHANCE FOR SEVERE WEATHER WILL BE WEST OF THE CAPITAL REGION...ALTHOUGH RIGHT ALONG THE INSTABILITY GRADIENT FROM THE CAPITAL REGION SOUTHWARD TO THE MID HUDSON VALLEY COULD EXPERIENCE A FEW SEVERE STORMS AS WELL. THE BEST POTENTIAL FOR SEVERE WEATHER WILL BE ACROSS THE MOHAWK/SCHOHARIE VALLEYS...AND THE CATSKILLS. THIS IS WHERE THE 1500-2500 J/KG SBCAPE VALUES WILL BE FOUND. THE MAIN THREATS WILL BE DAMAGING WIND GUSTS AND LARGE HAIL...AS 850-500 MB LAPSE RATES ARE FORECAST TO BE AROUND 6.5-7.0 C/KM...WHICH IS NOT A HIGH AS EARLY THIS MORNING BUT STILL SIGNIFICANT. DEEP LAYER 0-6 KM BULK SHEAR OF 30-40 KT SHOULD BE MORE THAN SUFFICIENT FOR ORGANIZING STORMS INTO MULTICELL CLUSTERS/LINES...AND HIGH CAPE MAY LEAD TO STORM CLUSTERS FORMING SIGNIFICANT COLD POOLS. WILL MENTION ENHANCED WORDING IN FORECAST AND POTENTIAL FOR SEVERE WEATHER IN THE HWO. TEMPERATURES WILL BE NOTICEABLE COOLER COMPARED TO YESTERDAY...BUT STILL RUNNING ABOVE NORMAL. IT WILL STILL BE SOMEWHAT HUMID TO THE SOUTH AND WEST OF THE COLD FRONT WITH TEMPS MAINLY EXPECTED TO BE IN THE UPPER 70S TO PERHAPS LOWER 80S WEST OF ALBANY. && .SHORT TERM /8 PM THIS EVENING THROUGH SATURDAY/... AS OF 430 AM...THE BACK DOOR COLD FRONT SHOULD PUSH THROUGH THE ENTIRE AREA BY LATE THIS EVENING. WILL CARRY SLIGHT CHANCE TO AS HIGH AS LOW CHANCE POPS ALONG FAR WESTERN ZONES DURING THE LATTER PART OF THE EVENING AS MODELS INDICATING THE FRONT MAY STALL OUT CLOSE TO OUR AREA BUT LIKELY TO OUR SOUTHWEST. WILL MAINTAIN JUST SLIGHT CHANCE POPS FRIDAY INTO FRIDAY NIGHT...AGAIN SOUTH AND WEST OF THE CAPITAL REGION...CLOSE THE LINGERING BOUNDARY. INSTABILITY LOOKS TO BE VERY MEAGER...SO NO MENTION OF THUNDER PAST THIS EVENING. TEMPS WILL BE PLEASANT WITH A NOTICEABLE DROP IN HUMIDITY TONIGHT INTO FRIDAY...WITH MAX TEMPS EXPECTED TO BE IN THE MID TO UPPER 70S. A WEAK COOL FRONT OR SURFACE TROF IS FORECAST TO PASS THROUGH THE REGION IN NORTHWEST FLOW ALOFT ON SATURDAY. THE NAM12 IS MOST AGGRESSIVE TRIGGERING SHOWERS DURING THE AFTERNOON. FOR NOW WILL MENTION LOW CHANCE POPS FOR MUCH OF THE AREA. SBCAPE VALUES APPROACHING 500 J/KG...SO WILL ADD SLIGHT CHANCE OF THUNDER WITH LOW-TOPPED CONVECTION. MAX TEMPS EXPECTED TO REACH UPPER 70S IN MOST VALLEY LOCATIONS. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... GFS/NAM SHOW A TROF PASSING BY TO OUR NORTH SATURDAY NIGHT...BUT GENERALLY MISSING THE ALY FORECAST AREA. WILL CONTINUE TO KEEP THE FORECAST DRY FOR NOW SINCE THE SYSTEM IS FORECAST TO BE WEAK... ESPECIALLY BY THE GFS. LOWS SATURDAY NIGHT WILL BE IN THE 50S. THE UPPER LEVEL RIDGE BUILDS INTO THE REGION AGAIN FOR SUNDAY INTO EARLY MONDAY. THIS WILL LEAD TO MAINLY CLEAR SKIES DURING THIS PERIOD AND A RETURN TO UNSEASONABLY WARM WEATHER. HIGHS SUNDAY WILL BE IN THE 80S...AND THE LOWS SUNDAY NIGHT IN THE 50S. THE RIDGE HOLDS INTO EARLY MONDAY...THEN THE GFS SWEEPS A COLD FRONT TOWARDS THE REGION DURING THE AFTERNOON...WITH THIS COLD FRONT PASSING THROUGH AND JUST EAST OF THE REGION BY MONDAY MORNING. GFS SUGGEST NUMEROUS SHOWERS/TSTMS ASSOCIATED WITH THIS FRONT AND WOULD SUPPORT AT LEAST LIKELY POPS. HOWEVER...THE ECMWF IS MUCH SLOWER AND WEAKER...WITH THE FRONT MOVING THROUGH ON TUESDAY. DUE TO THE UNCERTAINTY IN THE MODELS...WILL ONLY FORECAST A 30 TO 40 PERCENT CHANCE OF SHOWERS/TSTMS WITH THIS COLD FRONT...BUT SPREAD THE POP OUT OVER A 30 TO 36 HOUR PERIOD FROM MONDAY AFTERNOON INTO TUESDAY. HIGHS MONDAY WILL BE IN THE UPPER 70S TO MID 80S...THEN COOLING OFF TO THE 70S ON TUESDAY. LOWS MONDAY NIGHT WILL BE IN THE 50S TO AROUND 60. A RETURN TO MAINLY FAIR WEATHER TUESDAY NIGHT AND WEDNESDAY...WITH NEAR NORMAL TEMPS. LOWS TUESDAY NIGHT WILL BE IN THE MID 40S TO MID 50S. HIGHS WEDNESDAY IN THE UPPER 60S TO MID 70S. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... VFR CONDITIONS WILL PREVAIL AT THE KGFL/KALB/KPOU TAF SITES FOR MOST OF THE TAF PERIOD ENDING AT 12Z FRIDAY. THE MAIN WEATHER ISSUES WILL BE CONVECTION/TSTMS THAT MAY OCCUR THIS AFTERNOON INTO TONIGHT. AT THIS POINT THE COVERAGE IS NOT EXPECTED TO BE WIDESPREAD...SO HAVE ONLY INDICATED VCSH AFTER 18Z...ALONG WITH THE CB QUALIFIER TO DENOTE THE POSSIBILITY OF CONVECTION. THE THREAT FOR PCPN/TSTMS WILL END FROM NORTHEAST TO SOUTHWEST. KGFL IS LIKELY TO SEE THE THREAT FOR CONVECTION END AROUND 02Z...04Z AT KALB...AND 08Z AT KPOU. THE OTHER PROBLEM WOULD BE THE FOG THREAT FOR TONIGHT. GETTING ANY FOG AT THE TAF SITES TONIGHT WILL BE HIGHLY DEPENDENT ON WHETHER ONR NOT THESE SITES GET ANY RAIN THIS AFTERNOON AND EVENING. AT THIS POINT HAVE ONLY FORECAST IFR FIG AT THE HIGHLY FOG PRONE KGFL SITE...WHILE VFR CONDITIONS ARE FORECAST THROUGH THE NITE AT KALB/KPOU. SURFACE WINDS WILL BE UNDER 10 KTS AT ALL THREE TAF SITES...MAINLY FROM AN EASTERLY DIRECTION. STRONGER WINDS ARE POSSIBLE IN ANY CONVECTION THAT AFFECTS THE TAF SITES THIS AFTERNOON AND EVENING. OUTLOOK... FRI-MON...VFR...NO SIG WX. && .FIRE WEATHER... A BACK DOOR COLD FRONT WILL CONTINUE TO SLOWLY DRIFT SOUTHWESTWARD ACROSS THE AREA TODAY...PROVIDING THE FOCUS FOR ADDITIONAL SHOWERS AND THUNDERSTORMS. SOME AREAS WILL RECEIVE A WETTING RAINFALL...WITH THE BEST CHANCE WEST OF THE CAPITAL REGION. THE COLD FRONT WILL PUSH THROUGH THE AREA BY TONIGHT...USHERING IN COOLER AND MAINLY DRY WEATHER FOR FRIDAY. MINIMUM RELATIVE HUMIDITY VALUES THIS AFTERNOON WILL RANGE FROM 30 TO 45 PERCENT ACROSS THE WESTERN AND SOUTHERN ADIRONDACKS...TO 45 TO 65 PERCENT ELSEWHERE. RH VALUES TONIGHT WILL RECOVER TO BETWEEN 85 AND 100 PERCENT. THE RELATIVE HUMIDITY WILL DROP TO AROUND 30 TO 45 PERCENT FRIDAY AFTERNOON. WINDS TODAY WILL BE EAST-NORTHEAST AROUND 5 TO 10 MPH...BECOMING EAST AROUND 5 MPH TONIGHT. WINDS ON FRIDAY WILL BE NORTHEAST-EAST AROUND 5 MPH. && .HYDROLOGY... NO WIDESPREAD HYDRO PROBLEMS EXPECTED THROUGH THE NEXT 5 DAYS. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY...WITH THE GREATER COVERAGE WEST OF THE CAPITAL REGION FOLLOWING THE GRADUAL PASSAGE OF A BACK DOOR COLD FRONT. SOME AREAS THAT ARE AFFECTED BY THE CONVECTION MAY RECEIVE ONE HALF TO ONE INCH OF RAIN IN A RELATIVELY SHORT AMOUNT OF TIME. THIS COULD LEAD TO PONDING OF WATER ON ROADS AND POOR DRAINAGE LOCATIONS AS WELL AS RAPID RISES ON SMALLER STREAMS. SHOWERS AND STORMS WILL BE MOVING FAIRLY QUICKLY FROM NORTH TO SOUTH...SO THE THREAT FOR HEAVY RAIN IN ONE GIVEN AREA WILL NOT LAST VERY LONG AND NO FLOODING IS EXPECTED. ONLY ISOLATED TO SCATTERED SHOWERS ARE EXPECTED FROM TONIGHT THROUGH SATURDAY...WITH GENERALLY LIGHT PRECIP AMOUNTS. DRIER WEATHER IS EXPECTED TO RETURN FOR SUNDAY INTO MONDAY. 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...NAS NEAR TERM...NAS