229 FXUS61 KOKX 222007 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 407 PM EDT WED MAY 22 2013 .SYNOPSIS... A STALLED FRONT WILL REMAIN IN THE VICINITY INTO THURSDAY. A COLD FRONT WILL THEN SLOWLY APPROACH FROM THE WEST THURSDAY...THEN MOVE INTO WESTERN PORTIONS OF THE TRI-STATE THURSDAY NIGHT. A WAVE OF LOW PRESSURE DEVELOPS ALONG THIS SLOW MOVING COLD FRONT FRIDAY...REMAINS JUST EAST OF THE REGION SATURDAY...AND THEN TRACKS NORTH ALONG THE NEW ENGLAND COAST ON SUNDAY. HIGH PRESSURE OVER THE GREAT LAKES BUILDS SOUTHEAST ACROSS THE AREA MONDAY INTO TUESDAY. A WARM FRONT WILL THEN APPROACH FROM THE SOUTHWEST BY MID WEEK. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... WEAK FRONTAL BOUNDARY REMAINS STALLED JUST TO THE W AND S OF THE AREA...WITH A MARINE AIRMASS REMAINING IN PLACE. THIS FRONT SHOULD NOT MOVE MUCH...IF AT ALL TONIGHT...SO WOULD EXPECT MOST IF NOT ALL PRECIPITATION TO GO N OF THE AREA. THIS IS CONSISTENT WITH THE HRRR AND RAP...WHICH HAVE HAD THE BEST HANDLE ON THIS FRONT AND THE WEATHER TODAY BY FAR...ALONG WITH THE NAM AND SREF. BASED ON THIS HAVE GONE BASICALLY DRY ACROSS THE S 2/3 OF THE CWA THIS EVENING...WITH SLIGHT CHANCE POPS FAR N TIER...THEN SLIGHT CHANCE POPS THROUGHOUT OVERNIGHT IN RESPONSE TO AN APPROACHING 700-500 HPA SHORTWAVE. WITH MARINE LAYER INTACT - WOULD EXPECT LOW CLOUD DECK TO RE- ESTABLISH ITSELF ACROSS THE AREA OVERNIGHT. COULD SEE PATCHY FOG AS WELL - POSSIBLY LOCALLY DENSE NEAR THE ATLANTIC COAST. FOR LOWS USED A BLEND OF 50 PERCENT MAV GUIDANCE WITH 25 PERCENT MET GUIDANCE AND 25 PERCENT NAM 2-METER TEMPERATURES. FORECASTING LOWS 10-15 DEGREES ABOVE NORMAL. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... MIXING ASSOCIATED WITH PASSING 700-500 HPA SHORTWAVE THURSDAY MORNING SHOULD ERODE THE MARINE INVERSION - BUT STILL WILL BE LEFT WITH QUITE A BIT OF MID TO HIGH CLOUDS WITH MOIST SW FLOW ALOFT. PRE-FRONTAL TROUGH MOVING INTO THE LOWER HUDSON VALLEY/NE NJ THURSDAY AFTERNOON SHOULD SERVE AS TRIGGER FOR SCT-NUMEROUS SHRA WITH EMBEDDED TSRA. LIKELY POPS MAINLY FROM NYC-INTERIOR SW CT ZONES ON W AND CHANCE POPS EAST OF THAT LINE. SOME SUGGESTION FROM NAM/GFS THAT EASTERN AREAS WILL REMAIN DRY THURSDAY...BUT FOR NOW TOO MUCH LOW-MID LEVEL MOISTURE AND INCREASING LOW LEVEL JET TO FORECAST THAT AT THIS TIME. WITH 30-35 KT BULK SHEAR...1000-1500 J/KG OF CAPE AND BULK RICHARDSON NUMBERS 15-30 HAVE THE POTENTIAL FOR ISOLATED SEVERE STORMS THURSDAY AFTERNOON ACROSS NE NJ/LOWER HUDSON VALLEY AND MAYBE NYC AND SW CT ZONES. MAIN THREAT IS GUSTY WINDS AND LARGE HAIL. ALSO NEED TO WATCH FOR LOW LEVEL HELICITY WITH S SFC FLOW AND SW FLOW AT 850 HPA. FOR HIGHS THURSDAY USED A BLEND OF MIXING DOWN FROM 975 HPA NEAR THE COAST AND 950 HPA INLAND...WITH NAM 2-METER TEMPERATURES AND A BLEND OF MAV AND MET GUIDANCE. FORECASTING VALUES AROUND NORMAL EAST TO A FEW DEGREES ABOVE NORMAL WEST. DEEP SW FLOW ALOFT...BECOMES DIFFLUENT AT 500 HPA AFTER MIDNIGHT. HAVE THE POTENTIAL FOR HEAVY RAINFALL AS A RESULT. REFER TO THE HYDROLOGY SECTION FOR DETAILS. SEVERE THREAT COULD LINGER INTO THE EVENING ACROSS WESTERN ZONES AS WELL. FOR LOWS THURSDAY NIGHT USED A BLEND OF MAV/MET GUIDANCE WITH VALUES FORECAST AROUND 10 DEGREES ABOVE NORMAL. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... MODELS HAVE TRENDED CONSIDERABLY SLOWER AND DEEPER WITH THE APPROACHING UPPER TROUGH OVER THE MID SECTION OF THE COUNTRY. THERE IS VERY GOOD AGREEMENT WITH THE 12Z GFS AND ECMWF ON TAKING A CLOSED UPPER LOW FROM THE MID ATLANTIC STATES ON FRI NE TO OVER NEW ENGLAND ON SUN. THE NAM AND GGEM ARE TRENDING IN THAT DIRECTION...BUT ARE MORE PROGRESSIVE BEYOND 00Z SAT. PREFERENCE AT THIS TIME IS TO GO WITH THE SLOWER GFS/ECMWF SOLUTION BASED ON MODEL TRENDS AND THE RUN TO RUN CONTINUITY BEING EXHIBITED OVER THE LAST SEVERAL MODEL CYCLES. AS FOR SENSIBLE WEATHER...THIS RESULTS IN A WET...COOL WEEKEND WITH THE POTENTIAL FOR ANOTHER 1 TO 2 INCHES OF RAINFALL IN THE FRI-SAT TIME FRAME. SINCE THIS IS A BIG ADJUSTMENT FROM THE PREVIOUS FORECAST...HAVE RAMPED UP RAIN CHANCES FRI INTO SAT...BUT THESE MAY BE UNDERDONE...ESPECIALLY FOR SAT WHERE THERE IS A TREND IN THE FORECAST TO DRY THINGS OUT SAT INTO SUN. LATEST ECMWF KEEPS CONDITIONS WET INTO SUN WITH A GUSTY NW FLOW ON THE BACKSIDE. SO THIS IS THE POINT IN THE FORECAST WHERE CONDITIONS MAY CONTINUE TO DETERIORATE WITH SUBSEQUENT MODEL RUNS. ONCE AGAIN...WHILE THE FORECAST HAS AGGRESSIVELY TAKEN A DOWNWARD NOTE FOR THE HOLIDAY WEEKEND...RAIN CHANCES MAY BE ON THE INCREASE SAT INTO SUN BASED ON LATEST TRENDS IN THE MODEL GUIDANCE. IN ADDITION...SOME OF THE RAINFALL ON FRI...OR AT LEAST THE FIRST HALF OF THE DAY MAY BE CONVECTIVE WITH LOCALIZED HEAVY RAINFALL WITH ANY EMBEDDED THUNDERSTORMS. THEREAFTER...THE AIRMASS STABILIZES IN THE LOW-LEVELS WITH POST-FRONTAL RAIN/SHOWERS...PRIMARILY DRIVEN BY FRONTOGENETIC FORCING ON THE BACKSIDE OF THE LOW. WIND GUSTS SAT INTO SUN MAY BE UP TO 35 MPH...BUT THIS IS THE POTENTIAL...WITH THE FORECASTS SIGNIFICANTLY LOWER AT THIS TIME. AS FOR TEMPS...DAYTIME HIGHS WITH THE CLOUD COVER AND RAIN WILL BE 5 TO 10 DEGREES BELOW NORMAL. STAYED BELOW GUIDANCE. OVERNIGHT LOWS WILL BE CLOSE TO SEASONABLE. A GRADUAL WARM-UP TO NEAR SEASONABLE LEVELS IS THEN FORECAST MON-WED. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... FRONTAL BOUNDARY CONTINUES TO LINGER OVER THE AREA THIS AFTERNOON. AS A RESULT...IMPROVEMENT HAS BEEN QUITE SLOW. IFR/MVFR CIGS AND VSBY GENERALLY THE STANDARD. SOME POTENTIAL FOR A LITTLE MORE IMPROVEMENT PRIMARILY AT NW TERMINALS. RECENT OBS SHOW WINDS FINALLY TURNING S AT KJFK/KEWR...WHICH MAY BE A SIGN OF BRIEFLY INCREASING VSBY/CIGS. HOWEVER...BASED ON CURRENT OBS AND DEVELOPING S WIND...GROWING POTENTIAL FOR IFR VSBY TO PUSH BACK INTO COASTAL TERMINALS OVER NEXT FEW HOURS. POTENTIAL FOR CONDITIONS TO DROP SOLIDLY INTO IFR AGAIN TONIGHT...HOWEVER MUCH UNCERTAINTY EXISTS OVER TIMING AND EXTENT. POTENTIAL ALSO EXISTS FOR LIFR/VLIFR ACROSS COASTAL TERMINALS. DID NOT SHOW TS IN TAFS ON THURSDAY JUST YET...AS UPPER-LEVEL FLOW INDICATES STORMS MAY BE SLOW TO APPROACH WESTERN TERMINALS AND COULD HOLD OFF UNTIL LATE IN THE DAY. HOWEVER...LOW END POTENTIAL EXISTS AT W TERMS GENERALLY 23/18Z THROUGH 24/00Z. NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KJFK FCSTER COMMENTS: POSSIBILITY FOR VSBY TO DROP QUICKER/LOWER THAN FORECAST LATE THIS AFTERNOON INTO THIS EVENING. KLGA FCSTER COMMENTS: POTENTIAL FOR CIGS TO GO VFR BRIEFLY THIS AFTERNOON AND EARLY THIS EVENING. WIND DIRECTION MAY STAY E/NE A COUPLE HOURS LONGER THAN INDICATED IN TAF. KEWR FCSTER COMMENTS: CIGS MAY RISE HIGHER THAN INDICATED IN TAF OVER NEXT 2-3 HOURS. POTENTIAL FOR VSBY/CIGS LOWER THAN FORECAST TONIGHT. KTEB FCSTER COMMENTS: CIGS MAY RISE HIGHER THAN INDICATED IN TAF OVER NEXT 2-3 HOURS. POTENTIAL FOR VSBY/CIGS LOWER THAN FORECAST TONIGHT. KHPN FCSTER COMMENTS: CIGS MAY RISE HIGHER THAN INDICATED IN TAF OVER NEXT 2-3 HOURS. POTENTIAL FOR VSBY/CIGS LOWER THAN FORECAST TONIGHT. KISP FCSTER COMMENTS: POSSIBILITY FOR VSBY TO DROP QUICKER/LOWER THAN FORECAST LATE THIS AFTERNOON INTO THIS EVENING. .OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY... .THURSDAY-FRIDAY...NUMEROUS SHRA AND TSTMS POSSIBLE....PRIMARILY THUR NIGHT AND FRIDAY. IFR POSSIBLE IN FOG AND STRATUS. .SATURDAY...SHRA LIKELY WITH MVFR OR LOWER. N WINDS 25-30G35KT. .SUNDAY...MOST LIKELY VFR WITH NW WINDS 20-25KT. POTENTIAL FOR G UP TO 40KT. .MONDAY...VFR. NW WINDS 15-20G25KT. && .MARINE... LATEST SATELLITE IMAGERY...WEB-CAMS...AND RAP SOUNDINGS WARRANT EXTENDING DENSE FOG ADVISORY FOR THE WATERS S/W OF LONG ISLAND THROUGH TONIGHT. MIGHT ULTIMATELY END UP NEED TO EXTEND INTO THURSDAY MORNING - BUT TO MUCH UNCERTAINTY WITH TIMING OF MIXING AHEAD OF APPROACHING SHORTWAVE LATE TONIGHT TO DO SO AT THIS TIME. SEAS ARE RUNNING 1-2 FT BELOW WAVEWATCH FORECAST - SO FOR NOW HAVE TAKEN 1 FT OFF OF WAVEWATCH THROUGH THURSDAY NIGHT. STILL EXPECT SEAS TO COME UP TO SCA LEVELS TONIGHT AND CONTINUE THROUGH THURSDAY NIGHT. WINDS ALSO INCREASE LATE TONIGHT AND REMAIN UP INTO THURSDAY NIGHT. INCREASING LOW LEVEL JET THROUGH THURSDAY NIGHT INCREASES POTENTIAL FOR SCA LEVEL GUSTS OVER THE COASTAL OCEAN WATERS - SO HAVE KEPT HEADLINE AS SCA VICE CONVERTING TO AN SCA FOR HAZARDOUS SEAS. MARINE INVERSION APPEARS WILL LIMIT MIXING - SO WHILE COULD SEE OCCASIONAL GUSTS TO 25 KT OVER THE REMAINDER OF THE WATERS FROM LATE TONIGHT INTO THURSDAY NIGHT - DO NOT HAVE CONFIDENCE TO ISSUE SCA AT THIS TIME FOR THE NON-OCEAN ZONES. THERE IS A GOOD POTENTIAL FOR SCA CONDITIONS TO CONTINUE THROUGH THE UPCOMING WEEKEND AS LOW PRESSURE FORMS OVER THE WATERS ON FRI AND LIFTS SLOWLY TO THE NORTH AND EAST. SCA CONDITIONS ARE BECOMING INCREASINGLY LIKELY...WITH THE POTENTIAL FOR GALE CONDITIONS SAT INTO SUN. WINDS AND SEAS BEGIN TO SUBSIDE LATE SUN INTO MON WITH HIGH PRESSURE BUILDING IN FROM THE GREAT LAKES REGION. && .HYDROLOGY... THERE IS THE POTENTIAL FOR AROUND 3/4 TO 1 INCH BASIN AVERAGE QPF THURSDAY AND THURSDAY NIGHT WITH LOCALLY HIGHER AMOUNTS. DO NOT EXPECT ANY WIDESPREAD FLOOD THREAT THURSDAY FROM ANY SHRA/TSRA BUT COULD SEE SOME MINOR FLOODING UNDER ANY STRONGER CONVECTION - ESPECIALLY IF THERE IS ANY TRAINING. THE HEAVIEST RAINFALL IN THIS TIME FRAME WILL BE LATE THURSDAY NIGHT - WITH LOCALIZED RAINFALL RATES OF 1-1.5 INCHES/HR POSSIBLE NOTING PRECIPITABLE WATERS OF 1.5-1/75 INCHES IN THIS TIME FRAME. IF THESE RATES ARE REALIZED...ESPECIALLY IF THE STORMS PRODUCING THEM PASS OVER AREAS RECEIVING LOCALLY HEAVY RAINFALL THURSDAY...THERE IS THE POTENTIAL FOR LOCALIZED FLASH FLOODING. THE THREAT FOR LOCALIZED HEAVY RAINFALL WILL CONTINUE INTO THE FIRST HALF OF FRI WITH EMBEDDED CONVECTION. THEREAFTER...A STRATIFORM RAIN AND/OR SHOWERS DEVELOPS ON THE BACKSIDE OF DEVELOPING LOW PRESSURE. AN ADDITIONAL 1 TO 2 INCHES OF RAINFALL IS POSSIBLE FRI INTO SAT. THIS MAY EXACERBATE ANY ONGOING FLOODING. RAIN MAY LINGER EVEN INTO SUN BASED ON LATEST MODEL TRENDS. 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. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...DENSE FOG ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ338-345-350- 353-355. SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ350-353-355. && $$ SYNOPSIS...MALOIT/DW NEAR TERM...MALOIT SHORT TERM...MALOIT LONG TERM...DW AVIATION...PICCA MARINE...MALOIT/DW HYDROLOGY...MALOIT/DW