Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 05/17/13


AREA FORECAST DISCUSSION
NWS ALBANY NY
950 AM EDT WED MAY 15 2013 .SYNOPSIS... A WARM FRONT WILL APPROACH TODAY BRINGING RAIN SHOWERS AND PERHAPS A THUNDERSTORM TO THE AREA...MAINLY DURING THE AFTERNOON AND EVENING HOURS. THEN A COLD FRONT WITH LIMITED MOISTURE WILL APPROACH AND MOVE THROUGH THE REGION LATE THURSDAY INTO THURSDAY EVENING. THE NEXT CHANCE FOR SOME WET WEATHER IS EXPECTED LATE IN THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 930 AM...RADAR/STLT LOOPS INDICATE CLOUDS AND SHOWERS MOVING IN FASTER THAN PREVIOUSLY FORECAST...AND HAVE ADJUSTED THE POP/WX/CLOUD GRIDS ACCORDINGLY THIS MORNING. HAVE ALSO RAISED THE OVERALL POP FOR TODAY TO LIKELY (AROUND 60 PERCENT)...AS RADAR COVERAGE APPEARS TO SUPPORT SOMEWHAT HIGHER POPS. .PREVIOUS DISCUSSION... STRONG SURFACE WARM FRONT AND MID LEVEL THETA-E ADVECTION ARE RESULTING IN ELEVATED SHOWERS AND SOME THUNDERSTORMS ACROSS THE GREAT LAKE STATE TRACKING EAST-SOUTHEAST ACROSS LOWER ONTARIO PROVINCE. PER THE NCEP MODEL SUITE AND HOURLY RAP UPDATES...THE WARM FRONT WILL APPROACH WESTERN AND CENTRAL NY THIS MORNING WITH SCATTERED SHOWERS EXPECTED AHEAD OF THIS FEATURE. WE WILL SLOWLY BRING UP POPS THROUGH THE MORNING HOURS. IT APPEARS THE WARM FRONT WILL BECOME PINCHED OFF ALONG THE I81 CORRIDOR INITIALLY THEN SOUTH OF I90 THROUGH THE AFTERNOON HOURS AS THE MAIN SURFACE LOW TRACKS ALONG THE ST LAWRENCE RIVER VALLEY. THE EML AND ASSOCIATED MID LEVEL LAPSE RATES ARE EXPECTED TO TRACK ACROSS PA/NJ AND MID ATLANTIC REGION WHERE THE SWODY1 SEE TEXT REMAINS IN PLACE. SO WHILE NO SEVERE WEATHER IS EXPECTED TODAY...WITH AN INCREASE IN THE WIND FIELDS AND HIGHER PWATS ADVECTING INTO THE REGION /AOA 1.30 INCHES/...WOULD NOT BE SURPRISED TO SEE SOME OF THE DEEPER CONVECTIVE ELEMENTS PRODUCING SUB-SEVERE WIND GUSTS. THE COLD FRONT /OR OCCLUDED FRONT/ IS EXPECTED TO PASS THROUGH THE HUDSON VALLEY REGION AROUND SUNSET. THIS WOULD BE THE WINDOW OF OPPORTUNITY FOR THOSE DEEPER CONVECTIVE ELEMENTS ASSUMING WE ARE ABLE TO ROOT THOSE SURFACE PARCELS IN THE WARM SECTOR. FOR NOW...PER THE EXPERIMENTAL REFLECTIVITY FORECASTS...WE WILL KEEP POPS BELOW LIKELY THRESHOLDS AND WATCH TRENDS THROUGH THE DAY. AS FOR TEMPERATURES...AFTER A CHILLY START...THE WARMER AIR SHOULD ASSIST WITH VALLEY TEMPS CLIMBING INTO THE MID-UPPER 60S...WITH 60-65F FOR THE HIGHER TERRAIN. TONIGHT...THE PASSAGE OF THE FRONT SHOULD BE EAST OF OUR NEW ENGLAND COUNTIES SHORTLY AFTER SUNSET WITH DRIER AIR ADVECTING INTO THE REGION. THIS WILL ALLOW FOR CLEARING SKIES AND CLOSE TO SEASONABLE OVERNIGHT LOWS...MAINLY LOWER TO MIDDLE 40S. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... THURSDAY AND THURSDAY NIGHT...A NARROW WEDGE OF HIGH PRESSURE WILL MOVE ACROSS THE REGION DURING THURSDAY WITH TRANQUIL CONDITIONS. HOWEVER...THE WESTERLY WINDS WILL BECOME QUITE BRISK AND GUSTY AS MIXING LAYER HEIGHTS CLIMB TO AROUND 8-10K FEET. WINDS RESIDING AT THIS LEVEL ARE EXPECTED TO BE AT OR ABOVE 40KTS. THE HIGHER TERRAIN AND SOME MESOSCALE IMPACTS FROM FUNNELING DOWN THE MOHAWK AND INTO THE TACONICS COULD POTENTIALLY BE PROBLEMATIC. THE AIR COMING OUT OF CANADA WILL NOT BE ESPECIALLY COOL THIS GO ROUND...WITH H850 TEMPERATURES ONLY COOLING TO AN AVERAGE OF +8C DURING THE DAY...LOWER-MIDDLE 70S FOR MANY LOCATIONS WITH UPPER 60S ACROSS THE DACKS AND SOUTHERN GREENS. NCEP MODEL SUITE AND INTERNATIONAL GUIDANCE ARE CONVERGING WITH A PASSAGE OF A SECONDARY COLD FRONT THURSDAY EVENING. WHILE MOISTURE WILL REMAIN RATHER MEAGER...CAN NOT RULE OUT A SHOWER OR TWO ACROSS THE DACKS...LAKE GEORGE SARATOGA REGION AND PORTIONS OF SOUTHERN VT SO WE WILL HOLD ONTO THE SLIGHT CHANCE POPS. FRIDAY...HIGH PRESSURE WILL BE STILL BE BUILDING IN FROM JAMES BAY OF CANADA AS THOSE H850 TEMPS DIP BACK INTO THE LOWER SINGLE DIGITS. IT SHOULD BE ANOTHER FINE SPRING DAY FILLED WITH MOSTLY SUNNY SKIES AND A NORTHWEST BREEZE BUT NOT AS STRONG AS THURSDAY. TEMPERATURES WILL TOP OUT AROUND 70 IN THE HUDSON VALLEY...60S HIGHER TERRAIN. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE FIRST HALF OF THE PERIOD LOOKS RATHER BENIGN...AS A LARGE AREA OF HIGH PRESSURE BUILDS ACROSS THE REGION FROM THE GREAT LAKES AND SOUTHEAST CANADA FRIDAY NIGHT INTO SATURDAY. WITH A NORTHWEST FLOW REGIME...THIS PATTERN SHOULD BRING MAINLY CLEAR AND COOL NIGHTS...WITH SEASONABLY WARM DAYS AND SOME FAIR WEATHER CUMULUS BUILDING DURING THE AFTERNOON HOURS. WINDS WILL TURN SOUTHERLY ON SUNDAY...AS A RETURN FLOW AROUND DEPARTING HIGH PRESSURE OFF THE NEW ENGLAND COAST DEVELOPS. THIS WILL SIGNIFY THE START OF A WARMING TREND...BUT THERE COULD BE A FEW EXTRA CLOUDS AROUND AND PERHAPS A BRIEF SHOWER SUNDAY INTO SUNDAY NIGHT WITHIN THE WARM ADVECTION REGIME. OTHERWISE...MODELS IN GOOD AGREEMENT WITH BUILDING AN UPPER LEVEL RIDGE WITH A SURGE OF WARMTH ACROSS THE REGION MONDAY INTO TUESDAY OF NEXT WEEK. SOME DIFFERENCES IN THAT THE GFS HAS A FEW WRINKLES UNDER THE RIDGE WITH A FEW WEAK DISTURBANCES MOVING THROUGH...WHILE THE ECMWF IS SHOWING MORE OF A CLASSIC UPPER RIDGE WITH A MORE AMPLIFIED PATTERN. EITHER WAY IT LOOKS LIKE A DECENT WARMUP...BUT CHANCES FOR RAINFALL ARE MORE UNCERTAIN. WILL MENTION SLIGHT CHANCE POPS FOR NOW MONDAY INTO MONDAY NIGHT...INCREASING TO CHANCE FOR TUESDAY AS THE RIDGE IS FORECAST TO START FLATTENING BY THEN. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... VFR CONDITIONS ARE GENERALLY EXPECTED TO PREVAIL THROUGH MUCH OF THE 24 HOUR TAF PERIOD ENDING 12Z THURSDAY. HOWEVER...THERE IS A CHANCE FOR SOME INTERMITTENT MVFR OR EVEN BRIEF IFR CONDITIONS TODAY ASSOCIATED WITH SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS. AN APPROACHING SURFACE WARM FRONT AND UPPER LEVEL DISTURBANCE WILL BE RESPONSIBLE FOR THE INCREASING CHANCES FOR SHOWERS BY LATE THIS MORNING OR EARLY AFTERNOON INTO EARLY EVENING. EXPECTING COVERAGE TO BE SCATTERED...SO WILL CONTINUE TO MENTION VCSH AT ALL THE TERMINALS. MODELS FORECASTING THE BEST INSTABILITY TO BE DISPLACED SOUTH OF THE REGION...HOWEVER SOME LIMITED INSTABILITY AND FAIRLY POTENT DYNAMICS/LIFT COULD RESULT IN SOME THUNDER. SHOWERS SHOULD SHIFT EAST OF OUR AREA AND INTO NEW ENGLAND THIS EVENING WITH GRADUALLY IMPROVING CONDITIONS. THERE IS A CHANCE FOR SOME FOG FORMATION...MAINLY FOR KGFL/KPOU WHERE WINDS WILL BECOME NEAR CALM OVERNIGHT...WHILE A PERSISTENT BREEZE AROUND 5 KT SHOULD PRECLUDE FOG FORMING AT KALB/KPSF. WINDS WILL INCREASE FROM THE SOUTH AROUND 10 TO 15 KT WITH GUSTS AROUND 20 KT LATE THIS MORNING CONTINUING THROUGH THE EARLY EVENING. A BOUNDARY WILL MOVE THROUGH AROUND THE 00Z THURSDAY TIME FRAME...WHICH WILL SHIFT WINDS TO THE WEST. OUTLOOK... THU...VFR. NO SIG WX. BREEZY. FRI-SAT...VFR. NO SIG WX. SUN...VFR...SLGT CHC -SHRA. && .FIRE WEATHER... WIND GUSTS UP TO 30 MPH ARE POSSIBLE TODAY... WIND GUSTS UP TO 40 MPH ARE EXPECTED ON THURSDAY... THERE WILL BE SCATTERED SHOWERS AND PERHAPS A THUNDERSTORM TODAY AS A WARM FRONT APPROACHES. MINIMUM RH VALUES TODAY ARE EXPECTED TO REMAIN IN THE 40 PERCENTILE. SOUTHERLY WINDS OF 10 TO 20 MPH ARE EXPECTED WITH GUSTS UP TO 30 MPH POSSIBLE. TONIGHT...DRIER CONDITIONS WITH A GRADUAL REDUCTION IN WIND GUSTS. MAXIMUM RH VALUES SHOULD REBOUND TO BETWEEN 80 AND 100 PERCENT...ESPECIALLY IN LOCATIONS WHERE PRECIPITATION OCCURRED. THURSDAY...A BREEZY DRY DAY WITH WESTERLY WINDS AVERAGING 15 TO 25 MPH...WITH GUSTS TO 40 MPH EXPECTED. RH VALUES LOOK TO DROP TO AN AVERAGE 30 PERCENT. DEPENDING ON GREEN-UP STATUS FIRE WEATHER HEADLINES MIGHT HAVE TO BE BROACHED. A SHOWER IS POSSIBLE IN THE ADIRONDACKS AND SOUTHERN GREENS BY LATE IN THE DAY AS A SECONDARY COLD FRONT APPROACHES. OTHERWISE IT WILL BE MIX OF CLOUDS AND SUNSHINE. FRIDAY AND SATURDAY LOOK DRY WITH LESS WIND AND MORE NORMAL RECOVERIES AT NIGHT. && .HYDROLOGY... CHANCES OF RAIN SHOWERS AND PERHAPS A THUNDERSTORM WILL INCREASE TODAY...MAINLY DURING THE AFTERNOON AND EVENING HOURS AS A WARM FRONT APPROACHES. RAINFALL AMOUNTS WEDNESDAY AND WEDNESDAY NIGHT ARE GENERALLY EXPECTED TO BE AROUND OR A LITTLE UNDER A QUARTER OF AN INCH. THIS RAINFALL SHOULD HAVE LITTLE OR NO EFFECT ON WATERSHEDS IN OUR HYDRO SERVICE AREA /HSA/. AFTER THAT...MAINLY DRY WEATHER IS EXPECTED THROUGH AT LEAST THE FIRST HALF OF THE WEEKEND. 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. && .CLIMATE... THE GROWING SEASON IS UNDERWAY ACROSS THE MID HUDSON VALLEY...GREATER CAPITAL DISTRICT...LAKE GEORGE SARATOGA REGION AND SOUTHERN LITCHFIELD COUNTY CONNECTICUT. START DATES FOR THE REST OF EAST CENTRAL NY AND ADJACENT WESTERN NEW ENGLAND ARE AS FOLLOWS... MAY 15TH...THE MOHAWK VALLEY...EASTERN CATSKILLS...TACONICS... BENNINGTON COUNTY VT...THE BERKSHIRES AND LITCHFIELD HILLS. MAY 20TH...EASTERN WINDHAM COUNTY VT. MAY 25TH...THE SOUTHERN ADIRONDACKS AND WESTERN WINDHAM COUNTY VT. DURING THE GROWING SEASON FREEZE WARNINGS ARE ISSUED WHEN THE TEMPERATURES ARE FORECAST TO BE 32 DEGREES OR LOWER...AND FROST ADVISORIES ARE ISSUED WHEN THE TEMPERATURES ARE FORECAST TO BE IN THE 33 TO 36 DEGREES RANGE. THE START OF THE GROWING SEASON FOR A GIVEN AREA IS BASED ON THE MEDIAN DATE OF THE LAST SPRING FREEZE BASED ON 1981-2010 NORMALS AND IN COORDINATION WITH NEIGHBORING NWS OFFICES. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...BGM NEAR TERM...GJM SHORT TERM...BGM LONG TERM...JPV AVIATION...JPV FIRE WEATHER...HWJIV/BGM HYDROLOGY...BGM CLIMATE...IAA
AREA FORECAST DISCUSSION
NWS ALBANY NY
659 AM EDT WED MAY 15 2013 .SYNOPSIS... A WARM FRONT WILL APPROACH TODAY BRINGING RAIN SHOWERS AND PERHAPS A THUNDERSTORM TO THE AREA...MAINLY DURING THE AFTERNOON AND EVENING HOURS. THEN A COLD FRONT WITH LIMITED MOISTURE WILL APPROACH AND MOVE THROUGH THE REGION LATE THURSDAY INTO THURSDAY EVENING. THE NEXT CHANCE FOR SOME WET WEATHER IS EXPECTED DURING THE SECOND HALF OF THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM...ALL HEADLINES HAVE BEEN ALLOWED TO EXPIRE. OTHERWISE...HIGH AND MID LEVEL CLOUDS ARE INCREASING FROM WEST TO EAST WITH REGIONAL RADAR MOSAIC REVEALING THE LEADING EDGE OF THE SHOWERS WAS STILL WEST OF I81. EXTRAPOLATION OF THESE SHOWERS /IF THEY HOLD TOGETHER/ WOULD ARRIVE INTO THE WESTERN COUNTIES TOWARD 14Z AND THE HUDSON RIVER VALLEY REGION TOWARD 16Z. NO OTHER CHANGES TO THE FORECAST AT THE PRESENT TIME... STRONG SURFACE WARM FRONT AND MID LEVEL THETA-E ADVECTION ARE RESULTING IN ELEVATED SHOWERS AND SOME THUNDERSTORMS ACROSS THE GREAT LAKE STATE TRACKING EAST-SOUTHEAST ACROSS LOWER ONTARIO PROVINCE. PER THE NCEP MODEL SUITE AND HOURLY RAP UPDATES...THE WARM FRONT WILL APPROACH WESTERN AND CENTRAL NY THIS MORNING WITH SCATTERED SHOWERS EXPECTED AHEAD OF THIS FEATURE. WE WILL SLOWLY BRING UP POPS THROUGH THE MORNING HOURS. IT APPEARS THE WARM FRONT WILL BECOME PINCHED OFF ALONG THE I81 CORRIDOR INITIALLY THEN SOUTH OF I90 THROUGH THE AFTERNOON HOURS AS THE MAIN SURFACE LOW TRACKS ALONG THE ST LAWRENCE RIVER VALLEY. THE EML AND ASSOCIATED MID LEVEL LAPSE RATES ARE EXPECTED TO TRACK ACROSS PA/NJ AND MID ATLANTIC REGION WHERE THE SWODY1 SEE TEXT REMAINS IN PLACE. SO WHILE NO SEVERE WEATHER IS EXPECTED TODAY...WITH AN INCREASE IN THE WIND FIELDS AND HIGHER PWATS ADVECTING INTO THE REGION /AOA 1.30 INCHES/...WOULD NOT BE SURPRISED TO SEE SOME OF THE DEEPER CONVECTIVE ELEMENTS PRODUCING SUB-SEVERE WIND GUSTS. THE COLD FRONT /OR OCCLUDED FRONT/ IS EXPECTED TO PASS THROUGH THE HUDSON VALLEY REGION AROUND SUNSET. THIS WOULD BE THE WINDOW OF OPPORTUNITY FOR THOSE DEEPER CONVECTIVE ELEMENTS ASSUMING WE ARE ABLE TO ROOT THOSE SURFACE PARCELS IN THE WARM SECTOR. FOR NOW...PER THE EXPERIMENTAL REFLECTIVITY FORECASTS...WE WILL KEEP POPS BELOW LIKELY THRESHOLDS AND WATCH TRENDS THROUGH THE DAY. AS FOR TEMPERATURES...AFTER A CHILLY START...THE WARMER AIR SHOULD ASSIST WITH VALLEY TEMPS CLIMBING INTO THE MID-UPPER 60S...WITH 60-65F FOR THE HIGHER TERRAIN. TONIGHT...THE PASSAGE OF THE FRONT SHOULD BE EAST OF OUR NEW ENGLAND COUNTIES SHORTLY AFTER SUNSET WITH DRIER AIR ADVECTING INTO THE REGION. THIS WILL ALLOW FOR CLEARING SKIES AND CLOSE TO SEASONABLE OVERNIGHT LOWS...MAINLY LOWER TO MIDDLE 40S. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... THURSDAY AND THURSDAY NIGHT...A NARROW WEDGE OF HIGH PRESSURE WILL MOVE ACROSS THE REGION DURING THURSDAY WITH TRANQUIL CONDITIONS. HOWEVER...THE WESTERLY WINDS WILL BECOME QUITE BRISK AND GUSTY AS MIXING LAYER HEIGHTS CLIMB TO AROUND 8-10K FEET. WINDS RESIDING AT THIS LEVEL ARE EXPECTED TO BE AT OR ABOVE 40KTS. THE HIGHER TERRAIN AND SOME MESOSCALE IMPACTS FROM FUNNELING DOWN THE MOHAWK AND INTO THE TACONICS COULD POTENTIALLY BE PROBLEMATIC. THE AIR COMING OUT OF CANADA WILL NOT BE ESPECIALLY COOL THIS GO ROUND...WITH H850 TEMPERATURES ONLY COOLING TO AN AVERAGE OF +8C DURING THE DAY...LOWER-MIDDLE 70S FOR MANY LOCATIONS WITH UPPER 60S ACROSS THE DACKS AND SOUTHERN GREENS. NCEP MODEL SUITE AND INTERNATIONAL GUIDANCE ARE CONVERGING WITH A PASSAGE OF A SECONDARY COLD FRONT THURSDAY EVENING. WHILE MOISTURE WILL REMAIN RATHER MEAGER...CAN NOT RULE OUT A SHOWER OR TWO ACROSS THE DACKS...LAKE GEORGE SARATOGA REGION AND PORTIONS OF SOUTHERN VT SO WE WILL HOLD ONTO THE SLIGHT CHANCE POPS. FRIDAY...HIGH PRESSURE WILL BE STILL BE BUILDING IN FROM JAMES BAY OF CANADA AS THOSE H850 TEMPS DIP BACK INTO THE LOWER SINGLE DIGITS. IT SHOULD BE ANOTHER FINE SPRING DAY FILLED WITH MOSTLY SUNNY SKIES AND A NORTHWEST BREEZE BUT NOT AS STRONG AS THURSDAY. TEMPERATURES WILL TOP OUT AROUND 70 IN THE HUDSON VALLEY...60S HIGHER TERRAIN. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE FIRST HALF OF THE PERIOD LOOKS RATHER BENIGN...AS A LARGE AREA OF HIGH PRESSURE BUILDS ACROSS THE REGION FROM THE GREAT LAKES AND SOUTHEAST CANADA FRIDAY NIGHT INTO SATURDAY. WITH A NORTHWEST FLOW REGIME...THIS PATTERN SHOULD BRING MAINLY CLEAR AND COOL NIGHTS...WITH SEASONABLY WARM DAYS AND SOME FAIR WEATHER CUMULUS BUILDING DURING THE AFTERNOON HOURS. WINDS WILL TURN SOUTHERLY ON SUNDAY...AS A RETURN FLOW AROUND DEPARTING HIGH PRESSURE OFF THE NEW ENGLAND COAST DEVELOPS. THIS WILL SIGNIFY THE START OF A WARMING TREND...BUT THERE COULD BE A FEW EXTRA CLOUDS AROUND AND PERHAPS A BRIEF SHOWER SUNDAY INTO SUNDAY NIGHT WITHIN THE WARM ADVECTION REGIME. OTHERWISE...MODELS IN GOOD AGREEMENT WITH BUILDING AN UPPER LEVEL RIDGE WITH A SURGE OF WARMTH ACROSS THE REGION MONDAY INTO TUESDAY OF NEXT WEEK. SOME DIFFERENCES IN THAT THE GFS HAS A FEW WRINKLES UNDER THE RIDGE WITH A FEW WEAK DISTURBANCES MOVING THROUGH...WHILE THE ECMWF IS SHOWING MORE OF A CLASSIC UPPER RIDGE WITH A MORE AMPLIFIED PATTERN. EITHER WAY IT LOOKS LIKE A DECENT WARMUP...BUT CHANCES FOR RAINFALL ARE MORE UNCERTAIN. WILL MENTION SLIGHT CHANCE POPS FOR NOW MONDAY INTO MONDAY NIGHT...INCREASING TO CHANCE FOR TUESDAY AS THE RIDGE IS FORECAST TO START FLATTENING BY THEN. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... VFR CONDITIONS ARE GENERALLY EXPECTED TO PREVAIL THROUGH MUCH OF THE 24 HOUR TAF PERIOD ENDING 12Z THURSDAY. HOWEVER...THERE IS A CHANCE FOR SOME INTERMITTENT MVFR OR EVEN BRIEF IFR CONDITIONS TODAY ASSOCIATED WITH SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS. AN APPROACHING SURFACE WARM FRONT AND UPPER LEVEL DISTURBANCE WILL BE RESPONSIBLE FOR THE INCREASING CHANCES FOR SHOWERS BY LATE THIS MORNING OR EARLY AFTERNOON INTO EARLY EVENING. EXPECTING COVERAGE TO BE SCATTERED...SO WILL CONTINUE TO MENTION VCSH AT ALL THE TERMINALS. MODELS FORECASTING THE BEST INSTABILITY TO BE DISPLACED SOUTH OF THE REGION...HOWEVER SOME LIMITED INSTABILITY AND FAIRLY POTENT DYNAMICS/LIFT COULD RESULT IN SOME THUNDER. SHOWERS SHOULD SHIFT EAST OF OUR AREA AND INTO NEW ENGLAND THIS EVENING WITH GRADUALLY IMPROVING CONDITIONS. THERE IS A CHANCE FOR SOME FOG FORMATION...MAINLY FOR KGFL/KPOU WHERE WINDS WILL BECOME NEAR CALM OVERNIGHT...WHILE A PERSISTENT BREEZE AROUND 5 KT SHOULD PRECLUDE FOG FORMING AT KALB/KPSF. WINDS WILL INCREASE FROM THE SOUTH AROUND 10 TO 15 KT WITH GUSTS AROUND 20 KT LATE THIS MORNING CONTINUING THROUGH THE EARLY EVENING. A BOUNDARY WILL MOVE THROUGH AROUND THE 00Z THURSDAY TIME FRAME...WHICH WILL SHIFT WINDS TO THE WEST. OUTLOOK... THU...VFR. NO SIG WX. BREEZY. FRI-SAT...VFR. NO SIG WX. SUN...VFR...SLGT CHC -SHRA. && .FIRE WEATHER... WIND GUSTS UP TO 30 MPH ARE POSSIBLE TODAY... WIND GUSTS UP TO 40 MPH ARE EXPECTED ON THURSDAY... THERE WILL BE SCATTERED SHOWERS AND PERHAPS A THUNDERSTORM TODAY AS A WARM FRONT APPROACHES. MINIMUM RH VALUES TODAY ARE EXPECTED TO REMAIN IN THE 40 PERCENTILE. SOUTHERLY WINDS OF 10 TO 20 MPH ARE EXPECTED WITH GUSTS UP TO 30 MPH POSSIBLE. TONIGHT...DRIER CONDITIONS WITH A GRADUAL REDUCTION IN WIND GUSTS. MAXIMUM RH VALUES SHOULD REBOUND TO BETWEEN 80 AND 100 PERCENT...ESPECIALLY IN LOCATIONS WHERE PRECIPITATION OCCURRED. THURSDAY...A BREEZY DRY DAY WITH WESTERLY WINDS AVERAGING 15 TO 25 MPH...WITH GUSTS TO 40 MPH EXPECTED. RH VALUES LOOK TO DROP TO AN AVERAGE 30 PERCENT. DEPENDING ON GREEN-UP STATUS FIRE WEATHER HEADLINES MIGHT HAVE TO BE BROACHED. A SHOWER IS POSSIBLE IN THE ADIRONDACKS AND SOUTHERN GREENS BY LATE IN THE DAY AS A SECONDARY COLD FRONT APPROACHES. OTHERWISE IT WILL BE MIX OF CLOUDS AND SUNSHINE. FRIDAY AND SATURDAY LOOK DRY WITH LESS WIND AND MORE NORMAL RECOVERIES AT NIGHT. && .HYDROLOGY... CHANCES OF RAIN SHOWERS AND PERHAPS A THUNDERSTORM WILL INCREASE TODAY...MAINLY DURING THE AFTERNOON AND EVENING HOURS AS A WARM FRONT APPROACHES. RAINFALL AMOUNTS WEDNESDAY AND WEDNESDAY NIGHT ARE GENERALLY EXPECTED TO BE AROUND OR A LITTLE UNDER A QUARTER OF AN INCH. THIS RAINFALL SHOULD HAVE LITTLE OR NO EFFECT ON WATERSHEDS IN OUR HYDRO SERVICE AREA /HSA/. AFTER THAT...MAINLY DRY WEATHER IS EXPECTED THROUGH AT LEAST THE FIRST HALF OF THE WEEKEND. 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. && .CLIMATE... THE GROWING SEASON IS UNDERWAY ACROSS THE MID HUDSON VALLEY...GREATER CAPITAL DISTRICT...LAKE GEORGE SARATOGA REGION AND SOUTHERN LITCHFIELD COUNTY CONNECTICUT. START DATES FOR THE REST OF EAST CENTRAL NY AND ADJACENT WESTERN NEW ENGLAND ARE AS FOLLOWS... MAY 15TH...THE MOHAWK VALLEY...EASTERN CATSKILLS...TACONICS... BENNINGTON COUNTY VT...THE BERKSHIRES AND LITCHFIELD HILLS. MAY 20TH...EASTERN WINDHAM COUNTY VT. MAY 25TH...THE SOUTHERN ADIRONDACKS AND WESTERN WINDHAM COUNTY VT. DURING THE GROWING SEASON FREEZE WARNINGS ARE ISSUED WHEN THE TEMPERATURES ARE FORECAST TO BE 32 DEGREES OR LOWER...AND FROST ADVISORIES ARE ISSUED WHEN THE TEMPERATURES ARE FORECAST TO BE IN THE 33 TO 36 DEGREES RANGE. THE START OF THE GROWING SEASON FOR A GIVEN AREA IS BASED ON THE MEDIAN DATE OF THE LAST SPRING FREEZE BASED ON 1981-2010 NORMALS AND IN COORDINATION WITH NEIGHBORING NWS OFFICES. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...BGM NEAR TERM...BGM SHORT TERM...BGM LONG TERM...JPV AVIATION...JPV FIRE WEATHER...HWJIV/BGM HYDROLOGY...BGM CLIMATE...IAA
AREA FORECAST DISCUSSION
NWS ALBANY NY
655 AM EDT WED MAY 15 2013 .SYNOPSIS... A WARM FRONT WILL APPROACH TODAY BRINGING RAIN SHOWERS AND PERHAPS A THUNDERSTORM TO THE AREA...MAINLY DURING THE AFTERNOON AND EVENING HOURS. THEN A COLD FRONT WITH LIMITED MOISTURE WILL APPROACH AND MOVE THROUGH THE REGION LATE THURSDAY INTO THURSDAY EVENING. THE NEXT CHANCE FOR SOME WET WEATHER IS EXPECTED DURING THE SECOND HALF OF THE WEEKEND. && .NEAR TERM /TODAY THROUGH TONIGHT/... AS OF 630 AM...ALL HEADLINES HAVE BEEN ALLOWED TO EXPIRE. OTHERWISE...HIGH AND MID LEVEL CLOUDS ARE INCREASING FROM WEST TO EAST WITH REGIONAL RADAR MOSAIC REVEALING THE LEADING EDGE OF THE SHOWERS WAS STILL WEST OF I81. EXTRAPOLATION OF THESE SHOWERS /IF THEY HOLD TOGETHER/ WOULD ARRIVE INTO THE WESTERN COUNTIES TOWARD 14Z AND THE HUDSON RIVER VALLEY REGION TOWARD 16Z. NO OTHER CHANGES TO THE FORECAST AT THE PRESENT TIME... STRONG SURFACE WARM FRONT AND MID LEVEL THETA-E ADVECTION ARE RESULTING IN ELEVATED SHOWERS AND SOME THUNDERSTORMS ACROSS THE GREAT LAKE STATE TRACKING EAST-SOUTHEAST ACROSS LOWER ONTARIO PROVINCE. PER THE NCEP MODEL SUITE AND HOURLY RAP UPDATES...THE WARM FRONT WILL APPROACH WESTERN AND CENTRAL NY THIS MORNING WITH SCATTERED SHOWERS EXPECTED AHEAD OF THIS FEATURE. WE WILL SLOWLY BRING UP POPS THROUGH THE MORNING HOURS. IT APPEARS THE WARM FRONT WILL BECOME PINCHED OFF ALONG THE I81 CORRIDOR INITIALLY THEN SOUTH OF I90 THROUGH THE AFTERNOON HOURS AS THE MAIN SURFACE LOW TRACKS ALONG THE ST LAWRENCE RIVER VALLEY. THE EML AND ASSOCIATED MID LEVEL LAPSE RATES ARE EXPECTED TO TRACK ACROSS PA/NJ AND MID ATLANTIC REGION WHERE THE SWODY1 SEE TEXT REMAINS IN PLACE. SO WHILE NO SEVERE WEATHER IS EXPECTED TODAY...WITH AN INCREASE IN THE WIND FIELDS AND HIGHER PWATS ADVECTING INTO THE REGION /AOA 1.30 INCHES/...WOULD NOT BE SURPRISED TO SEE SOME OF THE DEEPER CONVECTIVE ELEMENTS PRODUCING SUB-SEVERE WIND GUSTS. THE COLD FRONT /OR OCCLUDED FRONT/ IS EXPECTED TO PASS THROUGH THE HUDSON VALLEY REGION AROUND SUNSET. THIS WOULD BE THE WINDOW OF OPPORTUNITY FOR THOSE DEEPER CONVECTIVE ELEMENTS ASSUMING WE ARE ABLE TO ROOT THOSE SURFACE PARCELS IN THE WARM SECTOR. FOR NOW...PER THE EXPERIMENTAL REFLECTIVITY FORECASTS...WE WILL KEEP POPS BELOW LIKELY THRESHOLDS AND WATCH TRENDS THROUGH THE DAY. AS FOR TEMPERATURES...AFTER A CHILLY START...THE WARMER AIR SHOULD ASSIST WITH VALLEY TEMPS CLIMBING INTO THE MID-UPPER 60S...WITH 60-65F FOR THE HIGHER TERRAIN. TONIGHT...THE PASSAGE OF THE FRONT SHOULD BE EAST OF OUR NEW ENGLAND COUNTIES SHORTLY AFTER SUNSET WITH DRIER AIR ADVECTING INTO THE REGION. THIS WILL ALLOW FOR CLEARING SKIES AND CLOSE TO SEASONABLE OVERNIGHT LOWS...MAINLY LOWER TO MIDDLE 40S. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... THURSDAY AND THURSDAY NIGHT...A NARROW WEDGE OF HIGH PRESSURE WILL MOVE ACROSS THE REGION DURING THURSDAY WITH TRANQUIL CONDITIONS. HOWEVER...THE WESTERLY WINDS WILL BECOME QUITE BRISK AND GUSTY AS MIXING LAYER HEIGHTS CLIMB TO AROUND 8-10K FEET. WINDS RESIDING AT THIS LEVEL ARE EXPECTED TO BE AT OR ABOVE 40KTS. THE HIGHER TERRAIN AND SOME MESOSCALE IMPACTS FROM FUNNELING DOWN THE MOHAWK AND INTO THE TACONICS COULD POTENTIALLY BE PROBLEMATIC. THE AIR COMING OUT OF CANADA WILL NOT BE ESPECIALLY COOL THIS GO ROUND...WITH H850 TEMPERATURES ONLY COOLING TO AN AVERAGE OF +8C DURING THE DAY...LOWER-MIDDLE 70S FOR MANY LOCATIONS WITH UPPER 60S ACROSS THE DACKS AND SOUTHERN GREENS. NCEP MODEL SUITE AND INTERNATIONAL GUIDANCE ARE CONVERGING WITH A PASSAGE OF A SECONDARY COLD FRONT THURSDAY EVENING. WHILE MOISTURE WILL REMAIN RATHER MEAGER...CAN NOT RULE OUT A SHOWER OR TWO ACROSS THE DACKS...LAKE GEORGE SARATOGA REGION AND PORTIONS OF SOUTHERN VT SO WE WILL HOLD ONTO THE SLIGHT CHANCE POPS. FRIDAY...HIGH PRESSURE WILL BE STILL BE BUILDING IN FROM JAMES BAY OF CANADA AS THOSE H850 TEMPS DIP BACK INTO THE LOWER SINGLE DIGITS. IT SHOULD BE ANOTHER FINE SPRING DAY FILLED WITH MOSTLY SUNNY SKIES AND A NORTHWEST BREEZE BUT NOT AS STRONG AS THURSDAY. TEMPERATURES WILL TOP OUT AROUND 70 IN THE HUDSON VALLEY...60S HIGHER TERRAIN. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE FIRST HALF OF THE PERIOD LOOKS RATHER BENIGN...AS A LARGE AREA OF HIGH PRESSURE BUILDS ACROSS THE REGION FROM THE GREAT LAKES AND SOUTHEAST CANADA FRIDAY NIGHT INTO SATURDAY. WITH A NORTHWEST FLOW REGIME...THIS PATTERN SHOULD BRING MAINLY CLEAR AND COOL NIGHTS...WITH SEASONABLY WARM DAYS AND SOME FAIR WEATHER CUMULUS BUILDING DURING THE AFTERNOON HOURS. WINDS WILL TURN SOUTHERLY ON SUNDAY...AS A RETURN FLOW AROUND DEPARTING HIGH PRESSURE OFF THE NEW ENGLAND COAST DEVELOPS. THIS WILL SIGNIFY THE START OF A WARMING TREND...BUT THERE COULD BE A FEW EXTRA CLOUDS AROUND AND PERHAPS A BRIEF SHOWER SUNDAY INTO SUNDAY NIGHT WITHIN THE WARM ADVECTION REGIME. OTHERWISE...MODELS IN GOOD AGREEMENT WITH BUILDING AN UPPER LEVEL RIDGE WITH A SURGE OF WARMTH ACROSS THE REGION MONDAY INTO TUESDAY OF NEXT WEEK. SOME DIFFERENCES IN THAT THE GFS HAS A FEW WRINKLES UNDER THE RIDGE WITH A FEW WEAK DISTURBANCES MOVING THROUGH...WHILE THE ECMWF IS SHOWING MORE OF A CLASSIC UPPER RIDGE WITH A MORE AMPLIFIED PATTERN. EITHER WAY IT LOOKS LIKE A DECENT WARMUP...BUT CHANCES FOR RAINFALL ARE MORE UNCERTAIN. WILL MENTION SLIGHT CHANCE POPS FOR NOW MONDAY INTO MONDAY NIGHT...INCREASING TO CHANCE FOR TUESDAY AS THE RIDGE IS FORECAST TO START FLATTENING BY THEN. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH MUCH OF THE 24 HOUR TAF PERIOD ENDING 06Z THURSDAY. HOWEVER...THERE IS A CHANCE FOR SOME INTERMITTENT MVFR OR EVEN BRIEF IFR CONDITIONS TODAY ASSOCIATED WITH SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS. AN APPROACHING SURFACE WARM FRONT AND UPPER LEVEL DISTURBANCE WILL BE RESPONSIBLE FOR THE INCREASING CHANCES FOR SHOWERS FROM LATE THIS MORNING THROUGH THE AFTERNOON. EXPECTING COVERAGE TO BE SCATTERED...SO WILL MENTION VCSH AT ALL THE TERMINALS FOR NOW. MODELS FORECASTING THE BEST INSTABILITY TO BE DISPLACED SOUTH OF THE REGION...HOWEVER SOME LIMITED INSTABILITY AND FAIRLY POTENT DYNAMICS/LIFT COULD RESULT IN SOME THUNDER. SHOWERS SHOULD SHIFT EAST OF OUR AREA AND INTO NEW ENGLAND THIS EVENING. WINDS WILL INITIALLY BE NEAR CALM...THEN INCREASE FROM THE SOUTH AROUND 10 TO 15 KT WITH GUSTS NEAR 20 KT LATE THIS MORNING CONTINUING THROUGH THE EARLY EVENING. A BOUNDARY WILL MOVE THROUGH AROUND THE 00Z THURSDAY TIME FRAME...WHICH WILL SHIFT WINDS TO THE WEST. OUTLOOK... THU...VFR. NO SIG WX. BREEZY. FRI-SAT...VFR. NO SIG WX. SUN...VFR...SLGT CHC -SHRA. && .FIRE WEATHER... ...WIND GUSTS UP TO 30 MPH ARE POSSIBLE TODAY... ...WIND GUSTS UP TO 40 MPH ARE EXPECTED ON THURSDAY... THERE WILL BE SCATTERED SHOWERS AND PERHAPS A THUNDERSTORM TODAY AS A WARM FRONT APPROACHES. MINIMUM RH VALUES TODAY ARE EXPECTED TO REMAIN IN THE 40 PERCENTILE. SOUTHERLY WINDS OF 10 TO 20 MPH ARE EXPECTED WITH GUSTS UP TO 30 MPH POSSIBLE. TONIGHT...DRIER CONDITIONS WITH A GRADUAL REDUCTION IN WIND GUSTS. MAXIMUM RH VALUES SHOULD REBOUND TO BETWEEN 80 AND 100 PERCENT...ESPECIALLY IN LOCATIONS WHERE PRECIPITATION OCCURRED. THURSDAY...A BREEZY DRY DAY WITH WESTERLY WINDS AVERAGING 15 TO 25 MPH...WITH GUSTS TO 40 MPH EXPECTED. RH VALUES LOOK TO DROP TO AN AVERAGE 30 PERCENT. DEPENDING ON GREEN-UP STATUS FIRE WEATHER HEADLINES MIGHT HAVE TO BE BROACHED. A SHOWER IS POSSIBLE IN THE ADIRONDACKS AND SOUTHERN GREENS BY LATE IN THE DAY AS A SECONDARY COLD FRONT APPROACHES. OTHERWISE IT WILL BE MIX OF CLOUDS AND SUNSHINE. FRIDAY AND SATURDAY LOOK DRY WITH LESS WIND AND MORE NORMAL RECOVERIES AT NIGHT. && .HYDROLOGY... CHANCES OF RAIN SHOWERS AND PERHAPS A THUNDERSTORM WILL INCREASE TODAY...MAINLY DURING THE AFTERNOON AND EVENING HOURS AS A WARM FRONT APPROACHES. RAINFALL AMOUNTS WEDNESDAY AND WEDNESDAY NIGHT ARE GENERALLY EXPECTED TO BE AROUND OR A LITTLE UNDER A QUARTER OF AN INCH. THIS RAINFALL SHOULD HAVE LITTLE OR NO EFFECT ON WATERSHEDS IN OUR HYDRO SERVICE AREA /HSA/. AFTER THAT...MAINLY DRY WEATHER IS EXPECTED THROUGH AT LEAST THE FIRST HALF OF THE WEEKEND. 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. && .CLIMATE... THE GROWING SEASON IS UNDERWAY ACROSS THE MID HUDSON VALLEY...GREATER CAPITAL DISTRICT...LAKE GEORGE SARATOGA REGION AND SOUTHERN LITCHFIELD COUNTY CONNECTICUT. START DATES FOR THE REST OF EAST CENTRAL NY AND ADJACENT WESTERN NEW ENGLAND ARE AS FOLLOWS... MAY 15TH...THE MOHAWK VALLEY...EASTERN CATSKILLS...TACONICS... BENNINGTON COUNTY VT...THE BERKSHIRES AND LITCHFIELD HILLS. MAY 20TH...EASTERN WINDHAM COUNTY VT. MAY 25TH...THE SOUTHERN ADIRONDACKS AND WESTERN WINDHAM COUNTY VT. DURING THE GROWING SEASON FREEZE WARNINGS ARE ISSUED WHEN THE TEMPERATURES ARE FORECAST TO BE 32 DEGREES OR LOWER...AND FROST ADVISORIES ARE ISSUED WHEN THE TEMPERATURES ARE FORECAST TO BE IN THE 33 TO 36 DEGREES RANGE. THE START OF THE GROWING SEASON FOR A GIVEN AREA IS BASED ON THE MEDIAN DATE OF THE LAST SPRING FREEZE BASED ON 1981-2010 NORMALS AND IN COORDINATION WITH NEIGHBORING NWS OFFICES. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...FROST ADVISORY UNTIL 7 AM EDT THIS MORNING FOR CTZ001-013. NY...FROST ADVISORY UNTIL 7 AM EDT THIS MORNING FOR NYZ038>040- 047>053-058>061-063>066. FREEZE WARNING UNTIL 7 AM EDT THIS MORNING FOR NYZ041-043-054- 083-084. MA...FROST ADVISORY UNTIL 7 AM EDT THIS MORNING FOR MAZ025. FREEZE WARNING UNTIL 7 AM EDT THIS MORNING FOR MAZ001. VT...FREEZE WARNING UNTIL 7 AM EDT THIS MORNING FOR VTZ013. && $$ SYNOPSIS...BGM NEAR TERM...BGM SHORT TERM...BGM LONG TERM...JPV AVIATION...JPV FIRE WEATHER...HWJIV/BGM HYDROLOGY...BGM CLIMATE...IAA WWW.WEATHER.GOV/ALBANY
AREA FORECAST DISCUSSION
NWS ALBANY NY
418 AM EDT WED MAY 15 2013 .SYNOPSIS... A WARM FRONT WILL APPROACH TODAY BRINGING RAIN SHOWERS AND PERHAPS A THUNDERSTORM TO THE AREA...MAINLY DURING THE AFTERNOON AND EVENING HOURS. THEN A COLD FRONT WITH LIMITED MOISTURE WILL APPROACH AND MOVE THROUGH THE REGION LATE THURSDAY INTO THURSDAY EVENING. THE NEXT CHANCE FOR SOME WET WEATHER IS EXPECTED DURING THE SECOND HALF OF THE WEEKEND. && .NEAR TERM /TODAY THROUGH TONIGHT/... STRONG SURFACE WARM FRONT AND MID LEVEL THETA-E ADVECTION ARE RESULTING IN ELEVATED SHOWERS AND SOME THUNDERSTORMS ACROSS THE GREAT LAKE STATE TRACKING EAST-SOUTHEAST ACROSS LOWER ONTARIO PROVINCE. PER THE NCEP MODEL SUITE AND HOURLY RAP UPDATES...THE WARM FRONT WILL APPROACH WESTERN AND CENTRAL NY THIS MORNING WITH SCATTERED SHOWERS EXPECTED AHEAD OF THIS FEATURE. WE WILL SLOWLY BRING UP POPS THROUGH THE MORNING HOURS. IT APPEARS THE WARM FRONT WILL BECOME PINCHED OFF ALONG THE I81 CORRIDOR INITIALLY THEN SOUTH OF I90 THROUGH THE AFTERNOON HOURS AS THE MAIN SURFACE LOW TRACKS ALONG THE ST LAWRENCE RIVER VALLEY. THE EML AND ASSOCIATED MID LEVEL LAPSE RATES ARE EXPECTED TO TRACK ACROSS PA/NJ AND MID ATLANTIC REGION WHERE THE SWODY1 SEE TEXT REMAINS IN PLACE. SO WHILE NO SEVERE WEATHER IS EXPECTED TODAY...WITH AN INCREASE IN THE WIND FIELDS AND HIGHER PWATS ADVECTING INTO THE REGION /AOA 1.30 INCHES/...WOULD NOT BE SURPRISED TO SEE SOME OF THE DEEPER CONVECTIVE ELEMENTS PRODUCING SUB-SEVERE WIND GUSTS. THE COLD FRONT /OR OCCLUDED FRONT/ IS EXPECTED TO PASS THROUGH THE HUDSON VALLEY REGION AROUND SUNSET. THIS WOULD BE THE WINDOW OF OPPORTUNITY FOR THOSE DEEPER CONVECTIVE ELEMENTS ASSUMING WE ARE ABLE TO ROOT THOSE SURFACE PARCELS IN THE WARM SECTOR. FOR NOW...PER THE EXPERIMENTAL REFLECTIVITY FORECASTS...WE WILL KEEP POPS BELOW LIKELY THRESHOLDS AND WATCH TRENDS THROUGH THE DAY. AS FOR TEMPERATURES...AFTER A CHILLY START...THE WARMER AIR SHOULD ASSIST WITH VALLEY TEMPS CLIMBING INTO THE MID-UPPER 60S...WITH 60-65F FOR THE HIGHER TERRAIN. TONIGHT...THE PASSAGE OF THE FRONT SHOULD BE EAST OF OUR NEW ENGLAND COUNTIES SHORTLY AFTER SUNSET WITH DRIER AIR ADVECTING INTO THE REGION. THIS WILL ALLOW FOR CLEARING SKIES AND CLOSE TO SEASONABLE OVERNIGHT LOWS...MAINLY LOWER TO MIDDLE 40S. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... THURSDAY AND THURSDAY NIGHT...A NARROW WEDGE OF HIGH PRESSURE WILL MOVE ACROSS THE REGION DURING THURSDAY WITH TRANQUIL CONDITIONS. HOWEVER...THE WESTERLY WINDS WILL BECOME QUITE BRISK AND GUSTY AS MIXING LAYER HEIGHTS CLIMB TO AROUND 8-10K FEET. WINDS RESIDING AT THIS LEVEL ARE EXPECTED TO BE AT OR ABOVE 40KTS. THE HIGHER TERRAIN AND SOME MESOSCALE IMPACTS FROM FUNNELING DOWN THE MOHAWK AND INTO THE TACONICS COULD POTENTIALLY BE PROBLEMATIC. THE AIR COMING OUT OF CANADA WILL NOT BE ESPECIALLY COOL THIS GO ROUND...WITH H850 TEMPERATURES ONLY COOLING TO AN AVERAGE OF +8C DURING THE DAY...LOWER-MIDDLE 70S FOR MANY LOCATIONS WITH UPPER 60S ACROSS THE DACKS AND SOUTHERN GREENS. NCEP MODEL SUITE AND INTERNATIONAL GUIDANCE ARE CONVERGING WITH A PASSAGE OF A SECONDARY COLD FRONT THURSDAY EVENING. WHILE MOISTURE WILL REMAIN RATHER MEAGER...CAN NOT RULE OUT A SHOWER OR TWO ACROSS THE DACKS...LAKE GEORGE SARATOGA REGION AND PORTIONS OF SOUTHERN VT SO WE WILL HOLD ONTO THE SLIGHT CHANCE POPS. FRIDAY...HIGH PRESSURE WILL BE STILL BE BUILDING IN FROM JAMES BAY OF CANADA AS THOSE H850 TEMPS DIP BACK INTO THE LOWER SINGLE DIGITS. IT SHOULD BE ANOTHER FINE SPRING DAY FILLED WITH MOSTLY SUNNY SKIES AND A NORTHWEST BREEZE BUT NOT AS STRONG AS THURSDAY. TEMPERATURES WILL TOP OUT AROUND 70 IN THE HUDSON VALLEY...60S HIGHER TERRAIN. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE FIRST HALF OF THE PERIOD LOOKS RATHER BENIGN...AS A LARGE AREA OF HIGH PRESSURE BUILDS ACROSS THE REGION FROM THE GREAT LAKES AND SOUTHEAST CANADA FRIDAY NIGHT INTO SATURDAY. WITH A NORTHWEST FLOW REGIME...THIS PATTERN SHOULD BRING MAINLY CLEAR AND COOL NIGHTS...WITH SEASONABLY WARM DAYS AND SOME FAIR WEATHER CUMULUS BUILDING DURING THE AFTERNOON HOURS. WINDS WILL TURN SOUTHERLY ON SUNDAY...AS A RETURN FLOW AROUND DEPARTING HIGH PRESSURE OFF THE NEW ENGLAND COAST DEVELOPS. THIS WILL SIGNIFY THE START OF A WARMING TREND...BUT THERE COULD BE A FEW EXTRA CLOUDS AROUND AND PERHAPS A BRIEF SHOWER SUNDAY INTO SUNDAY NIGHT WITHIN THE WARM ADVECTION REGIME. OTHERWISE...MODELS IN GOOD AGREEMENT WITH BUILDING AN UPPER LEVEL RIDGE WITH A SURGE OF WARMTH ACROSS THE REGION MONDAY INTO TUESDAY OF NEXT WEEK. SOME DIFFERENCES IN THAT THE GFS HAS A FEW WRINKLES UNDER THE RIDGE WITH A FEW WEAK DISTURBANCES MOVING THROUGH...WHILE THE ECMWF IS SHOWING MORE OF A CLASSIC UPPER RIDGE WITH A MORE AMPLIFIED PATTERN. EITHER WAY IT LOOKS LIKE A DECENT WARMUP...BUT CHANCES FOR RAINFALL ARE MORE UNCERTAIN. WILL MENTION SLIGHT CHANCE POPS FOR NOW MONDAY INTO MONDAY NIGHT...INCREASING TO CHANCE FOR TUESDAY AS THE RIDGE IS FORECAST TO START FLATTENING BY THEN. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH MUCH OF THE 24 HOUR TAF PERIOD ENDING 06Z THURSDAY. HOWEVER...THERE IS A CHANCE FOR SOME INTERMITTENT MVFR OR EVEN BRIEF IFR CONDITIONS TODAY ASSOCIATED WITH SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS. AN APPROACHING SURFACE WARM FRONT AND UPPER LEVEL DISTURBANCE WILL BE RESPONSIBLE FOR THE INCREASING CHANCES FOR SHOWERS FROM LATE THIS MORNING THROUGH THE AFTERNOON. EXPECTING COVERAGE TO BE SCATTERED...SO WILL MENTION VCSH AT ALL THE TERMINALS FOR NOW. MODELS FORECASTING THE BEST INSTABILITY TO BE DISPLACED SOUTH OF THE REGION...HOWEVER SOME LIMITED INSTABILITY AND FAIRLY POTENT DYNAMICS/LIFT COULD RESULT IN SOME THUNDER. SHOWERS SHOULD SHIFT EAST OF OUR AREA AND INTO NEW ENGLAND THIS EVENING. WINDS WILL INITIALLY BE NEAR CALM...THEN INCREASE FROM THE SOUTH AROUND 10 TO 15 KT WITH GUSTS NEAR 20 KT LATE THIS MORNING CONTINUING THROUGH THE EARLY EVENING. A BOUNDARY WILL MOVE THROUGH AROUND THE 00Z THURSDAY TIME FRAME...WHICH WILL SHIFT WINDS TO THE WEST. OUTLOOK... THU...VFR. NO SIG WX. BREEZY. FRI-SAT...VFR. NO SIG WX. SUN...VFR...SLGT CHC -SHRA. && .FIRE WEATHER... ...WIND GUSTS UP TO 30 MPH ARE POSSIBLE TODAY... ...WIND GUSTS UP TO 40 MPH ARE EXPECTED ON THURSDAY... THERE WILL BE SCATTERED SHOWERS AND PERHAPS A THUNDERSTORM TODAY AS A WARM FRONT APPROACHES. MINIMUM RH VALUES TODAY ARE EXPECTED TO REMAIN IN THE 40 PERCENTILE. SOUTHERLY WINDS OF 10 TO 20 MPH ARE EXPECTED WITH GUSTS UP TO 30 MPH POSSIBLE. TONIGHT...DRIER CONDITIONS WITH A GRADUAL REDUCTION IN WIND GUSTS. MAXIMUM RH VALUES SHOULD REBOUND TO BETWEEN 80 AND 100 PERCENT...ESPECIALLY IN LOCATIONS WHERE PRECIPITATION OCCURRED. THURSDAY...A BREEZY DRY DAY WITH WESTERLY WINDS AVERAGING 15 TO 25 MPH...WITH GUSTS TO 40 MPH EXPECTED. RH VALUES LOOK TO DROP TO AN AVERAGE 30 PERCENT. DEPENDING ON GREEN-UP STATUS FIRE WEATHER HEADLINES MIGHT HAVE TO BE BROACHED. A SHOWER IS POSSIBLE IN THE ADIRONDACKS AND SOUTHERN GREENS BY LATE IN THE DAY AS A SECONDARY COLD FRONT APPROACHES. OTHERWISE IT WILL BE MIX OF CLOUDS AND SUNSHINE. FRIDAY AND SATURDAY LOOK DRY WITH LESS WIND AND MORE NORMAL RECOVERIES AT NIGHT. && .HYDROLOGY... CHANCES OF RAIN SHOWERS AND PERHAPS A THUNDERSTORM WILL INCREASE TODAY...MAINLY DURING THE AFTERNOON AND EVENING HOURS AS A WARM FRONT APPROACHES. RAINFALL AMOUNTS WEDNESDAY AND WEDNESDAY NIGHT ARE GENERALLY EXPECTED TO BE AROUND OR A LITTLE UNDER A QUARTER OF AN INCH. THIS RAINFALL SHOULD HAVE LITTLE OR NO EFFECT ON WATERSHEDS IN OUR HYDRO SERVICE AREA /HSA/. AFTER THAT...MAINLY DRY WEATHER IS EXPECTED THROUGH AT LEAST THE FIRST HALF OF THE WEEKEND. 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. && .CLIMATE... THE GROWING SEASON IS UNDERWAY ACROSS THE MID HUDSON VALLEY...GREATER CAPITAL DISTRICT...LAKE GEORGE SARATOGA REGION AND SOUTHERN LITCHFIELD COUNTY CONNECTICUT. START DATES FOR THE REST OF EAST CENTRAL NY AND ADJACENT WESTERN NEW ENGLAND ARE AS FOLLOWS... MAY 15TH...THE MOHAWK VALLEY...EASTERN CATSKILLS...TACONICS... BENNINGTON COUNTY VT...THE BERKSHIRES AND LITCHFIELD HILLS. MAY 20TH...EASTERN WINDHAM COUNTY VT. MAY 25TH...THE SOUTHERN ADIRONDACKS AND WESTERN WINDHAM COUNTY VT. DURING THE GROWING SEASON FREEZE WARNINGS ARE ISSUED WHEN THE TEMPERATURES ARE FORECAST TO BE 32 DEGREES OR LOWER...AND FROST ADVISORIES ARE ISSUED WHEN THE TEMPERATURES ARE FORECAST TO BE IN THE 33 TO 36 DEGREES RANGE. THE START OF THE GROWING SEASON FOR A GIVEN AREA IS BASED ON THE MEDIAN DATE OF THE LAST SPRING FREEZE BASED ON 1981-2010 NORMALS AND IN COORDINATION WITH NEIGHBORING NWS OFFICES. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...FROST ADVISORY UNTIL 7 AM EDT THIS MORNING FOR CTZ001-013. NY...FROST ADVISORY UNTIL 7 AM EDT THIS MORNING FOR NYZ038>040- 047>053-058>061-063>066. FREEZE WARNING UNTIL 7 AM EDT THIS MORNING FOR NYZ041-043-054- 083-084. MA...FROST ADVISORY UNTIL 7 AM EDT THIS MORNING FOR MAZ025. FREEZE WARNING UNTIL 7 AM EDT THIS MORNING FOR MAZ001. VT...FREEZE WARNING UNTIL 7 AM EDT THIS MORNING FOR VTZ013. && $$ SYNOPSIS...BGM NEAR TERM...BGM SHORT TERM...BGM LONG TERM...JPV AVIATION...JPV FIRE WEATHER...HWJIV/BGM HYDROLOGY...BGM CLIMATE...IAA WWW.WEATHER.GOV/ALBANY
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
310 AM EDT WED MAY 15 2013 .DISCUSSION... TODAY-TONIGHT... A LARGE HI PRES RIDGE EXTENDING FROM BERMUDA TO THE WRN GOMEX WILL DRIFT SLOWLY INTO THE ATLC UNDER THE INFLUENCE OF THE SRN BRANCH OF THE H30-H20 JET STREAM. POSITION OF THE RIDGE WILL MAINTAIN A STEADY E/SE BREEZE ACRS CENTRAL FL. EVENING SOUNDINGS MEASURED A DRY AND VERY STABLE AIRMASS OVERHEAD...PWAT VALUES BTWN 0.6"-0.8" WITH A SHARP SUBSIDENCE INVERSION IN THE H85-H70 LYR. RAP ANALYSIS INDICATING H100-H85 MEAN RH VALUES BTWN 70-80PCT...IR SAT PICS SHOWING A FEW POCKETS OF STRATOCU ALONG AND N OF THE BAHAMA BANK. BASE OF THE SUBSIDENCE INVERSION WILL CAP VERTICAL MOTION BTWN 5-6KFT...ONLY SCT CLOUD COVER ANTICIPATED. DESPITE NEAR FULL SUN... THE ONSHORE BREEZE WILL KEEP MAX TEMPS SLIGHTLY BLO AVG...L80S ALONG THE COAST...M80S INTERIOR. WEAK PGRAD AND CLEAR SKIES TONIGHT WILL ALLOW THE BNDRY LYR TO DECOUPLE...RESULTING IN GOOD RADIATIONAL CONDITIONS. MIN TEMPS GENERALLY IN THE L/M60S INTERIOR...IMMEDIATE SPACE/TREASURE COAST WILL HOLD IN THE M/U60S. LATE WEEK...LITTLE CHANGE IN LARGE SCALE FEATURES IS ADVERTISED THROUGH THE END OF THE WEEK. AN WEST TO EAST ELONGATED HIGH PRESSURE RIDGE FROM THE GULF TO THE WRN ATLC BASIN WILL CONTINUE TO PRODUCE GENERALLY FAIR CONDITIONS LOCALLY WITH SEASONAL TEMPS. STRENGTH OF THE RIDGE LOOKS TO EASE FRI AS A SHORTWAVE ALOFT MOVES ACROSS THE GULF AND FL REGION. WL KEEP POP JUST BELOW MENTIONABLE LEVEL THROUGH FRI BUT WOULDN`T BE SURPRISED TO SEE A DIURNAL STORM OR TWO WEST OF ORLANDO DURING LATE FRI AFTERNOON. EXTENDED...NEXT WEEK BEGINS WITH WEAKENING HIGH PRESSURE NORTH OF THE AREA. SOMEWHAT HIGHER MOISTURE COMBINED WITH LESS CONV INHIBITION WITH WEAKENING OF RIDGE NR AREA WL ALLOW FOR ISOLD/SCT DIURNAL PCPN. INLAND STORM CHCS IMPROVE SAT/SUN AND BEST PLACEMENT WL BE INLAND WHERE MID TO LATE AFTERNOON BOUNDARY MERGERS WL FORCE A LITTLE MORE ACTIVITY. PRESENCE OF ONSHORE FLOW WL KEEP TEMPS MODERATED WITH NEAR SEASONAL READINGS AND PARTLY CLOUDY SKIES. EARLY SIGNALS BEYOND DAY 7 SHOW HIGHER MOISTURE AND WOULD EXPECT A MENTIONABLE RAIN CHC FOR THE EXTENDED PERIODS PAST THIS TIME. && .AVIATION... THRU 16/00Z...VFR ALL SITES. BTWN 15/18Z-15/22Z...OCNL SFC WND G20KTS S OF KVRB. && .MARINE... TODAY-TONIGHT...HI PRES RIDGE AXIS OVER N FL WILL MAINTAIN A GENTLE TO MODERATE E/SE BREEZE...SEAS 2-3FT NEARSHORE AND 3-4FT OFFSHORE MAINLY IN A 9SEC SWELL. LATE WEEK...ONSHORE GRADIENT WINDS AROUND 5 TO 10 KTS WITH SOME HIGHER AFTERNOON GUSTS WL CONTINUE INTO THE WEEKEND. SEAS GENERALLY WL REMAIN IN THE 2-4FT RANGE. && .FIRE WEATHER... TODAY-TONIGHT...E/SE SFC/TRANSPORT FLOW WILL GRADUALLY MODIFY THE DRY AIR OVER CENTRAL FL. MIN RH VALUES ALONG AND N OF THE I-4 CORRIDOR MAY FALL BLO 35PCT FOR 4-6HRS...NO OTHER FIRE WX ISSUES ANTICIPATED. CONTINUATION OF ONSHORE FLOW THROUGH THE REMAINDER OF THE WEEK WL MITIGATE ANY LOW RH DURATION CONCERNS. && .PRELIMINARY POINT TEMPS/POPS... DAB 80 63 83 66 / 0 0 10 10 MCO 86 63 86 65 / 0 0 0 10 MLB 81 66 82 69 / 0 0 0 10 VRB 80 65 82 66 / 0 0 0 10 LEE 86 63 87 67 / 0 0 10 10 SFB 86 63 87 66 / 0 0 10 10 ORL 86 63 87 68 / 0 0 0 10 FPR 80 65 82 66 / 0 0 0 10 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ SHORT TERM...BRAGAW LONG TERM....PENDERGRAST
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
242 AM EDT WED MAY 15 2013 .SYNOPSIS... 06Z WATER VAPOR AND H4 RAP ANALYSIS SHOWING A BROAD MID/UPPER LEVEL RIDGE IN CONTROL FROM THE CENTRAL GULF OF MEXICO TO THE SOUTHEASTERN CONUS AND FLORIDA PENINSULA. WV IMAGERY INDICATES A SWATH OF VERY DRY MID/UPPER LEVEL AIR OVER OUR HEADS THIS MORNING...AND THIS IS CONFIRMED WITH A QUICK GLANCE AT THE 15/00Z KTBW SOUNDING WHICH SHOWS THIS DRY COLUMN ALOFT AND CONTINUES THE TREND DOWN ALL THE WAY TO THE SURFACE BOUNDARY LAYER. DUE TO THE DRY COLUMN AND OVERALL SUPPRESSION UNDERNEATH THE UPPER RIDGE...OUR SKIES ARE MOSTLY CLEAR THIS MORNING. FURTHER DOWNSTREAM WE FIND AN ILL-DEFINED TROUGH/DISTURBANCE CROSSING THE MEXICAN PLATEAU/SOUTHERN PLAINS WHICH WILL APPROACH OUR AREA LATER IN THE WEEK WITH LITTLE IF ANY FANFARE. NORTHERN STREAM FLOW IS CURRENTLY RIDING ALONG AND JUST SOUTH OF THE U.S/CANADIAN BORDER BEFORE DIPPING INTO LONGWAVE TROUGHING NOW EXITING THE NORTHEAST AND MID-ATLANTIC COASTS. AT THE SURFACE...SUBTROPICAL RIDGE AXIS EXTENDS FROM OFF THE GA COAST BACK WESTWARD THROUGH THE NATURE COAST AND INTO THE NE GULF OF MEXICO. LIGHT GRADIENT ON THE SOUTH SIDE OF THE RIDGE AXIS IS PROVIDING A WEAK EAST/NE FLOW FOR MUCH OF THE FORECAST AREA. TEMPERATURES ARE ONCE AGAIN QUITE COOL FOR THE MIDDLE OF MAY. A NOTICEABLE WARMING OF THE OVERNIGHT LOWS IS EXPECTED INTO THE LATER PORTION OF THE WEEK. && .SHORT TERM (TODAY THROUGH FRIDAY)... TODAY/TONIGHT...STACKED RIDGING WILL CONTROL OUR WEATHER THROUGH THE NEXT 24 HOURS KEEPING THE FORECAST DRY WITH SEASONABLE DAYTIME TEMPERATURES AND SLIGHTLY BELOW NORMAL OVERNIGHT READINGS. MOSTLY CLEAR SKIES THIS MORNING WILL GIVE WAY TO A FEW-SCT CU FIELDS...ESPECIALLY SOUTH OF THE I-4 CORRIDOR...BUT STILL FEEL SAFE IN CALLING CONDITIONS MOSTLY SUNNY. SOME OF THE MORE SENSITIVE HI-RES CONVECTION ALLOWING MODELS ARE TRYING TO BRING A FEW ISOLATED SHOWERS WESTWARD FROM THE EAST COAST INTO THE SOUTHERN TIER OF ZONES. VERTICAL ANALYSIS OF THIS CORES SHOW THAT THEY FAIL TO EVEN REACH 10KFT AGL BEFORE A HOSTILE THETA-E ENVIRONMENT FOR DEEP CONVECTION RESULTS IN RAPID CU DISSIPATION. WILL DISREGARD ANY CHANCE OF EVEN LIGHT ISOLATED SHOWERS THIS AFTERNOON AND KEEP THE FORECAST DRY. TEMPERATURES WILL REBOUND NICELY INTO THE MID 80S AWAY FROM THE BEACHES WHERE AN AFTERNOON SEA-BREEZE WILL HOLD TEMPS DOWN A FEW DEGREES. THIS SEA-BREEZE SHOULD BE HELD VERY CLOSE TO THE COAST THROUGH THE AFTERNOON TO THE SOUTH OF TAMPA BAY WHERE 12-14 KNOTS OF FLOW JUST ABOVE THE SURFACE WILL BE SUFFICIENT TO SIGNIFICANTLY IMPEDE THE INLAND PROGRESS OF THE CIRCULATION. NORTH OF TAMPA BAY IN CLOSER PROXIMITY TO THE RIDGE AXIS...FLOW IS GENERALLY 10 KNOTS OR LESS AND WILL BE LESS EFFICIENT AT HOLDING BACK THE SEA-BREEZE. TEMPERATURES WILL BE MORE SEASONABLE TONIGHT WITH MANY LOCATIONS FAILING TO DROP OUT OF THE 60S. NORMALLY COLDER SPOTS ACROSS THE NATURE COAST AND INTERIOR SOUTHERN ZONES MAY BRIEFLY REACH THE UPPER 50S TOWARD SUNRISE. THURSDAY/THURSDAY NIGHT... MID/UPPER LEVEL RIDGE WILL QUICKLY BREAK DOWN AND BE SUPPRESSED SOUTHWARD IN RESPONSE TO THE APPROACH AND ARRIVING OF SHORTWAVE ENERGY MOVING EASTWARD ALONG THE NORTHERN GULF COAST. THE DISTURBANCE IS ACTUALLY DECENT IN TERMS OF THE OVERALL SYNOPTIC FORCING OVERSPREADING THE REGION...HOWEVER COLUMN MOISTURE BELOW 500MB WILL SIMPLY BE LACKING...AND THE ENVIRONMENT WILL REMAIN HOSTILE FOR CONVECTION TO BECOME ESTABLISH. CAN NEVER RULE OUT A FEW ISOLATED SHOWERS (ESPECIALLY NORTH OF I-4)...HOWEVER FAIRLY CONFIDENT THAT TEMPORAL AND/OR SPATIAL COVERAGE WILL BE SMALL ENOUGH TO LEAVE MENTION OUT OF THE CURRENT FORECAST. REALLY THE MAIN IMPACT WE SHOULD SEE FROM THIS PASSING ENERGY WILL BE A POSSIBLE BAND OF MID/HIGH LEVEL CLOUDS...AGAIN MAINLY OVER THE NORTHERN ZONES. HIGH TEMPERATURES THURSDAY WILL BE WELL UP INTO THE 80S INLAND...AND SLIGHTLY COOLER AT THE BEACHES AS FLOW AGAIN TURNS ONSHORE FOR THE AFTERNOON. LOW TEMPERATURES AT NIGHT ONLY DROP TO THE LOWER 60S FOR THE COOLEST SPOTS. FRIDAY... SHORTWAVE AXIS WILL CROSS THE AREA DURING THE DAY AND QUICKLY EXIT TO OUR EAST FRIDAY NIGHT. WILL SEE A SMALL INCREASE IN OVERALL COLUMN MOISTURE FOR MOST SPOTS AND THEREFORE ADDED IN A SLIGHT CHANCE 20% FOR AN AFTERNOON/EVENING SHOWER. HOWEVER...ANY CONVECTIVE CELLS WILL STILL HAVE TO OVERCOME A HOSTILE THETA-E ENVIRONMENT BETWEEN 5-15KFT. THIS HOSTILE ENVIRONMENT SHOULD KEEP COVERAGE QUITE LOW AND EXPECT MOST SPOTS TO ESCAPE WITH A DRY DAY. TEMPERATURES WILL AGAIN BE SEASONABLE...WITH WARMEST LOCATIONS FLIRTING WITH 90 BY MID/LATE AFTERNOON. ENJOY! && .LONG TERM (SATURDAY THROUGH NEXT TUESDAY)... UPPER LEVEL RIDGING HOLDS OVER THE GULF AND WESTERN GULF COAST FOR MOST OF THE WEEKEND AS A COUPLE OF SHORT WAVE TROUGHS...THE FIRST ONE OVER THE MID-MISSISSIPPI/OHIO VALLY REGION AND THE SECOND OFF THE SE U.S. COAST...SLIDE EAST. BY LATE SUN THE FIRST SHORT WAVE TROUGH IS OVER THE MID-ATLANTIC STATES WITH THE RIDGE AXIS IN THE CENTRAL GULF. THE RESULT FOR FL IS A GENERALLY WEAK PATTERN ALOFT. FOR THE START OF NEXT WEEK A ROBUST TROUGH OR LOW DROPS INTO THE NORTHERN/CENTRAL PLAINS AND MID-WEST AND MOVES EAST TO THE GREAT LAKES BY MID-WEEK WITH THE RIDGE WEAKLY MOVING OUT OVER THE ATLANTIC. AT THE SURFACE...HIGH PRESSURE OVER THE ATLANTIC ALONG 30 NORTH LATITUDE RIDGES WEST TO THE GULF COAST REGION THROUGH THE WEEKEND. ON MON AN AREA OF HIGH PRESSURE SLIDES OFFSHORE NEW ENGLAND AND MOVES SOUTH...REINFORCING THE HIGH ALONG 30 NORTH AS IT/S RIDGE AXIS REACHES TO THE GULF COAST/SE U.S. THE SURFACE RIDGE KEEPS EAST TO SE LOW LEVEL FLOW IN PLACE...BUT WEAK ENOUGH FOR AFTERNOON SEA BREEZES..WHICH PROVIDES A GRADUAL INCREASE IN MOISTURE. THIS MOISTURE ALONG WITH THE SEA BREEZES AND WEAK PATTERN ALOFT WILL PRODUCE SLIGHT CHANCE TO LOW END CHANCE SHOWERS AND STORMS...WITH TIMING AFTERNOON AND EARLY EVENING. TEMPERATURES WILL BE NEAR SEASONABLE. && .AVIATION... VFR CONDITIONS CONTINUE FOR THE NEXT 24 HOURS WITH SKC BECOMING FEW-SCT MAINLY CU/SC. EASTERLY WINDS EXCEPT FOR BAY/SEA BREEZE AT TPA/PIE/SRQ. && .MARINE... THE SUBTROPICAL RIDGE AXIS WILL REMAIN IN PLACE ACROSS THE NORTHEAST GULF OF MEXICO INTO THE UPCOMING WEEKEND. PATTERN THROUGH FRIDAY WILL RESULT IN GENERALLY EAST TO WEST FLOW DURING THE OVERNIGHT AND MORNING HOURS WITH THE FLOW THEN WEAKENING FOR THE AFTERNOON AND EVENING...WHILE ONSHORE SEA BREEZES DEVELOP NEAR THE COAST. WINDS WILL APPROACH EXERCISE CAUTION LEVELS FOR A TIME EARLY THIS MORNING...ESPECIALLY SOUTH OF TARPON SPRINGS...BUT THEN RELAX BY MIDDAY. ANOTHER BRIEF EASTERLY SURGE IS POSSIBLE TO THE SOUTH OF TAMPA BAY EARLY THURSDAY MORNING. && .FIRE WEATHER... HIGH PRESSURE WILL KEEP OUR WEATHER DRY AND GENERALLY QUIET THE NEXT SEVERAL DAYS. RELATIVE HUMIDITY VALUES ARE FORECAST TO DROP BELOW 35 PERCENT FOR A FEW HOURS THIS AFTERNOON AWAY FROM THE IMMEDIATE COAST...EXTEND DURATIONS OF THESE CRITICAL VALUES ARE GENERALLY NOT ANTICIPATED AND WILL NOT COINCIDE WITH ANY ZONES WHERE ERC VALUES ARE ABOVE 37. A SLOW INCREASE IN MOISTURE WILL CONTINUE INTO THURSDAY AND FRIDAY. CURRENT FORECAST HAS A BRIEF PERIOD OF NEAR 35 PERCENT RELATIVE HUMIDITY INLAND FROM THE I-75 CORRIDOR ON THURSDAY AND KEEPS ALL AREAS ABOVE CRITICAL VALUES OF RELATIVE HUMIDITY FOR FRIDAY. && .PRELIMINARY POINT TEMPS/POPS... TPA 87 67 87 70 / 0 0 0 0 FMY 88 64 88 68 / 05 0 10 10 GIF 87 64 88 67 / 0 0 10 10 SRQ 86 65 86 68 / 05 0 10 10 BKV 86 60 88 64 / 0 0 0 0 SPG 85 70 86 72 / 0 0 0 10 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA LONG TERM/AVIATION/DECISION SUPPORT...RUDE
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1003 PM CDT THU MAY 16 2013 .DISCUSSION... 930 PM CDT THE FORECAST FOR TONIGHT HAS BEEN TWEAKED SLIGHTLY...TO CONTINUE THE EVENING CHANCE OF THUNDER ACROSS THE SOUTHERN FORECAST AREA THROUGH THE NIGHT...AND TO NUDGE IT NORTH SOME. THE EVE WATER VAPOR LOOP DEPICTS THE CLOSED UPPER LOW ACROSS NORTHERN AR EASING ITS WAY NORTHEAST. AT THE SURFACE...THE PRIMARILY SYNOPTIC FRONT IS NEAR THE LOT/ILX CWA BORDER WITH A LAKE BREEZE HAVING PUSHED WELL INLAND. BETWEEN THESE TWO A FEW STORMS GENERATED...IT LOOKED LIKE ON A SLIGHTLY ELEVATED BOUNDARY JUST NORTH OF THE SURFACE BOUNDARY PER ILX RADAR. THESE MAY FESTER NORTHEAST ON THE AFOREMENTIONED MULTIPLE AREAS OF LOW-LEVEL CONVERGENCE FOR SEVERAL MORE HOURS...BUT ANY CG LIGHTNING HAS BEEN SPORADIC AT BEST AND WOULD EXPECT THAT TREND TO CONTINUE OR DIMINISH ALTOGETHER. THE HRRR DOES INDICATE THESE SHOWERS TO SORT OF OSCILLATE ALL THE WAY UP TO FAR NORTHEAST IL THROUGH EARLY OVERNIGHT. THE ILX VAD PROFILER INDICATES INCREASING SOUTHERLY FLOW BELOW 3K FT...NOW UP TO 30 KT. THE LOW-LEVEL JET IS NOT EXPECTED TO INCREASE MUCH FROM THAT MAGNITUDE AND POINT MORE INTO WESTERN IL. MOISTURE TRANSPORT IS MORE LIMITED TONIGHT SO NOT EXPECTING AS MUCH IF ANY ELEVATED CONVECTION...BUT COULD SEE SOME IN WESTERN IL WHERE A LITTLE MORE THETA-E ADVECTION AND CONVERGENCE AROUND 850MB IS FORECAST. THE LAKE BREEZE MADE IMPRESSIVE PROGRESS WSW THROUGH EARLY EVE AFTER SORT OF A SLOW START. A 30 DEGREE SPREAD AS OF 930 PM EXISTS ACROSS THE CWA SIMPLY FROM JUST THIS MESOSCALE BOUNDARY. HAVE ADJUSTED THE HOURLY TEMPERATURE FORECAST TO MEET TRENDS. THE LAV GUIDANCE HAS VERY LITTLE TEMPERATURE DROP FOR MANY POINTS THROUGH THE REST OF THE NIGHT...LIKELY DUE TO INCREASING CLOUD COVER. WHILE CAA OFF THE LAKE LIKELY WILL CREATE A LITTLE MORE DROP THAN IT ADVERTISES...THIS IS IN LINE WITH THE GOING MINIMUM TEMPERATURE FORECASTS. MTF //PREV DISCUSSION... 259 PM CDT TODAY`S FORECAST CHALLENGES CONTINUE TO BE DEALING WITH FRONTAL BOUNDARY CURRENTLY JUST SOUTH OF THE CWA...AND PERIODIC CONVECTIVE CHANCES THROUGH MID NEXT WEEK. TODAY AND TONIGHT... THIS AFTERNOON THE FRONT IS LOCATED JUST NORTH OF QUINCY IL EAST TO NEAR TERRE HAUTE INDIANA...AND HAS BEEN SLOWLY PUSHING NORTH THIS AFTERNOON. MODERATE INSTABILITY EXISTS SOUTH OF THE FRONT AND MAY LIFT INTO FAR SOUTHERN PORTIONS OF THE CWA LATE THIS EVENING BEFORE FADING NOCTURNALLY. MAINTAINED SLT CHC POPS FOR A FEW HOURS THIS EVENING WHEN THIS OCCURS...BUT OTHERWISE SHOULD BE FAIRLY QUIET PERIOD THROUGH TONIGHT. FRIDAY THROUGH SATURDAY... COMPACT SHORTWAVE NOTED ON WV IMAGERY THIS AFTERNOON OVER WESTERN NE/KS WILL CONTINUE ENE INTO WEST CENTRAL WISCONSIN BY FRIDAY AFTERNOON. AS THIS HAPPENS...SOUTHERLY FLOW INCREASE AT THE SURFACE AND SHOULD HELP PUSH THE BOUNDARY NORTH ACROSS THE AREA. DEWPOINTS RISE INTO THE MID 60S AND MODEST INSTABILITY DEVELOPS OUTSIDE OF FAR NE ILLINOIS WHERE ONSHORE WINDS WILL KEEP CONDITIONS COOLER/MORE STABLE. THIS INSTABILITY IS UNCAPPED...AND GIVEN THERE IS NO WELL DEFINED FOCUS FOR THUNDERSTORMS...EXPECT UNORGANIZED/SCATTERED CONVECTION TO DEVELOP WITHIN THE WARM SECTOR. MID LEVEL LAPSE RATES ARE PRETTY POOR...SO CONVECTION MAY STRUGGLE AT TIMES AND MAY LIMIT THE THUNDER CHANCES TO SOME DEGREE. MUCH OF THE SAME IS EXPECTED SATURDAY SO WILL MAINTAIN THE LOW POPS FOR DIURNALLY DRIVEN TSTORMS. SUNDAY THROUGH TUESDAY... THIS PERIOD CONTINUES TO LOOK ACTIVE AS THE OVERALL PATTERN AMPLIFIES WITH DEEP TROUGHING DEVELOPING ACROSS THE WESTERN CONUS...AND STRONG RIDGING EAST. THE H85 THERMAL RIDGE BEGINS TO WORK INTO THE AREA SUNDAY...AS WELL AS DRY AIR ALOFT AND THE EML LATER IN THE DAY HELPING TO STEEPEN LAPSE RATES ALOFT. NEGATIVELY TILTED TROUGH IS EXPECTED TO ROUND THE BASE OF THE LONGWAVE TROUGH SUNDAY LIFTING INTO THE MID MISSOURI VALLEY SUNDAY NIGHT. MODELS ARE MIXED ON WHETHER OR NOT THE CIN ERODES DURING THE DAYTIME...BUT IF IT DOES CHANCES WILL BE BEST OVER WESTERN PORTIONS OF THE CWA...SO HAVE MAINTAINED LOWER POPS. THERE MAY BE A BETTER CHANCE FOR CONVECTION OVERNIGHT AS A LOW LEVEL JET DEVELOPS JUST TO OUR WEST WITH LARGE SCALE ASCENT ASSOCIATED WITH AFOREMENTIONED TROUGH. ON MONDAY...THE GFS INDICATES ANOTHER LOWER AMPLITUDE DISTURBANCE WILL ROUND THE BASE OF THE LONGWAVE TROUGH AND LIFT INTO THE MID MISSISSIPPI VALLEY. THIS CONTINUES TO BE A DAY TO KEEP AN EYE ON FOR SEVERE WEATHER POTENTIAL. MODELS CONTINUE TO ADVERTISE MODERATE TO STRONG INSTABILITY IN PLACE OVERHEAD WITH MARGINAL SHEAR CONDITIONS TO SUPPORT SEVERE WEATHER. AS PREVIOUSLY MENTIONED...CONVECTION FROM THE PREVIOUS NIGHT...CLOUD COVER...AND OTHER SMALL SCALE FEATURES CANNOT BE RESOLVED THIS FAR OUT AND ADD A CONSIDERABLE AMOUNT OF UNCERTAINTY. WE SHOULD BEGIN TO GET A BETTER PICTURE THIS WEEKEND SO STAY TUNED FOR FORECAST UPDATES. DEPENDING ON THE SPEED OF THE SYSTEM...TUESDAY WILL ALSO HAVE TO BE MONITORED...PERHAPS WITH THE THREAT MORE FOCUSED ON THE EASTERN PORTIONS OF THE CWA. IN ADDITION TO THE SEVERE THREAT...MULTIPLE ROUNDS OF THUNDERSTORMS MOVING ALONG THE SLOW MOVING BOUNDARY SUNDAY NIGHT THROUGH TUESDAY WILL LEAD TO A INCREASED HEAVY RAIN AND FLOODING THREAT. FOR TEMPERATURES SUNDAY AND MONDAY...CONTINUE TO LEAN ON THE WARMER BIAS CORRECTED GEM WHICH HAPPENED TO VERIFY BEST WITH THE UNSEASONABLY HEAT TUESDAY. DEPENDING ON THE SPEED OF THE SYSTEM...CURRENT FORECAST TEMPS MAY BE A BIT ON THE COOL SIDE TUESDAY...PARTICULARLY THE EASTERN CWA. H85 TEMPS OF 16-18C AND H92 TEMPS OF 19-22C SHOULD SUPPORT TEMPERATURES WELL INTO THE 80S AND WOULDN`T BE SURPRISED TO SEE PLACES HIT 90S THOSE DAYS...BUT WILL REMAIN A BIT CONSERVATIVE GIVEN THE PRECIP CHANCES AND CLOUD COVER. DEUBELBEISS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 03Z... * NELY WINDS 5-10KT OVERNIGHT BECMG SELY TOMORROW MORNING THEN BACKING ELY IN THE AFTERNOON. * CHANCE TSRA/SHRA TOMORROW AFTERNOON/EVENING. KREIN //DISCUSSION...UPDATED 00Z... THE LAKE BREEZE HAS FINALLY PUSHED INLAND OF ORD/MDW/GYY AND SHOULD PUSH THROUGH DPA SOON AS WELL. THIS WILL SET UP ENELY WINDS OVER NERN IL/NWRN IN...BUT WILL LIKELY NOT IMPACT RFD WHICH SHOULD REMAIN SELY THROUGH THE NIGHT. HAVE BEEN MONITORING THE PROGRESSION OF THE LAKE BREEZE BOUNDARY TO THE SOUTHWEST ALONG WITH ANOTHER WEAK BOUNDARY MOVING NORTHWARD ALONG THE ILLINOIS/KANKAKEE RIVERS. THIS WEAK BOUNDARY SEPARATES SOUTHERLY FLOW WITH SLIGHTLY HIGHER DEWPOINTS. WILL NEED TO MONITOR THESE BOUNDARYS CLOSELY AS THEY APPROACH EACH OTHER FOR ANY SHRA/TSRA DEVELOPMENT...WHICH BASED ON CURRENT TRACK/TIMING WOULD BE INVOF KJOT AREA. OTHERWISE THE REMAINDER OF THE NIGHT SHOULD BE QUIET AT THE TERMINALS. FOCUS WILL THEN SHIFT TO TSRA POTENTIAL TOMORROW AFTERNOON. LATEST GUIDANCE INDICATES A WARM FRONT LIFTING INTO NRN IL/IN BY LATE TOMORROW AFTERNOON. MOISTURE POOLING ALONG THE BOUNDARY AND ISENTROPIC LIFT ALONG THE FRONTAL ZONE WILL PROVIDE ENOUGH FOCUS TO NECESSATE ADDING A PROB30 GROUP TO THE FORECAST. TIMING WILL BE THE MAIN QUESTION...BUT GENERALLY EXPECT THE BEST TIMING TO BE DURG THE LATE AFTERNOON/EARLY EVENING HOURS. KREIN //ORD AND MDW CONFIDENCE...UPDATED 03Z... * MODERATE TO HIGH CONFIDENCE IN WIND TRENDS. * MODERATE CONFIDENCE IN TSRA/SHRA CHANCES TOMORROW...BUT LOWER CONFIDENCE IN EXACT TIMING. KREIN //OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z... SATURDAY THROUGH WEDNESDAY...PERIODIC CHANCES FOR SHRA/TSRA... OTHERWISE...VFR. KREIN && .MARINE... 228 PM CDT RIDGING FROM HIGH PRESSURE CENTERED OVER WESTERN ONTARIO EXTENDS ACROSS LAKE MICHIGAN THIS AFTERNOON. WEAK LOW PRESSURE WILL DEVELOP AND MOVE UP THE OHIO RIVER VALLEY FRIDAY WITH ADDITIONAL LOW PRESSURE DEVELOPING ACROSS THE CENTRAL HIGH PLAINS. EAST TO NORTHEAST FLOW OVERALL WILL CONTINUE ACROSS THE LAKE...WITH ONSHORE FLOW IN AREAS WHERE THE PRESSURE GRADIENT IS WEAKER CAUSING SOME ERRATIC DIRECTIONS AT TIMES. STEADIER AND MORE UNIFORM WINDS WILL DEVELOP WITH TIME THROUGH TOMORROW WITH MORE OF AN EAST TO SOUTHEAST TREND. THE STRONGEST WINDS WILL OCCUR FRIDAY EVENING/NIGHT COINCIDENT WITH THE STRONGEST PRESSURE GRADIENT THANKS TO THE LOW PASSING TO THE SOUTHEAST. THE GRADIENT WEAKENS DURING THE DAY SATURDAY AS THE LOW DEPARTS TO THE EAST. LOW PRESSURE STRENGTHENS ACROSS THE CENTRAL/NORTHERN HIGH PLAINS INTO SUNDAY WHICH WILL GRADUALLY TIGHTEN THE PRESSURE GRADIENT ACROSS THE LAKE. THIS WILL ALLOW A STEADY SOUTH TO SOUTHEAST WIND TO DEVELOP ACROSS MOST OF THE LAKE...WITH A MORE EASTERLY DIRECTION ACROSS THE FAR NORTH WHERE A WARM FRONTAL BOUNDARY IS EXPECTED TO SET UP. THE MAIN LOW WILL MEANDER NORTHWARD BEFORE BEING PUSHED EASTWARD ACROSS MINNESOTA/IOWA SOMETIME TUESDAY OR WEDNESDAY WHICH WILL LIKELY PUSH THE FRONTAL BOUNDARY FURTHER SOUTH ACROSS THE LAKE LEADING TO EAST TO NORTHEAST WINDS NORTH AND SOUTH TO SOUTHWEST WINDS SOUTH BY MID WEEK. THE MAIN CONCERN WILL BE THE POTENTIAL FOR INCREASED GUSTINESS ACROSS THE NORTH AS COLDER AIR SETTLES IN ALLOWING SLIGHTLY INCREASED MIXING. OTHERWISE...GENERALLY STABLE LOW LEVEL AIR ACROSS THE LAKE WILL KEEP GUSTS TO A MINIMUM FROM TONIGHT THROUGH THE WEEKEND. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
939 PM CDT THU MAY 16 2013 .DISCUSSION... 930 PM CDT THE FORECAST FOR TONIGHT HAS BEEN TWEAKED SLIGHTLY...TO CONTINUE THE EVENING CHANCE OF THUNDER ACROSS THE SOUTHERN FORECAST AREA THROUGH THE NIGHT...AND TO NUDGE IT NORTH SOME. THE EVE WATER VAPOR LOOP DEPICTS THE CLOSED UPPER LOW ACROSS NORTHERN AR EASING ITS WAY NORTHEAST. AT THE SURFACE...THE PRIMARILY SYNOPTIC FRONT IS NEAR THE LOT/ILX CWA BORDER WITH A LAKE BREEZE HAVING PUSHED WELL INLAND. BETWEEN THESE TWO A FEW STORMS GENERATED...IT LOOKED LIKE ON A SLIGHTLY ELEVATED BOUNDARY JUST NORTH OF THE SURFACE BOUNDARY PER ILX RADAR. THESE MAY FESTER NORTHEAST ON THE AFOREMENTIONED MULTIPLE AREAS OF LOW-LEVEL CONVERGENCE FOR SEVERAL MORE HOURS...BUT ANY CG LIGHTNING HAS BEEN SPORADIC AT BEST AND WOULD EXPECT THAT TREND TO CONTINUE OR DIMINISH ALTOGETHER. THE HRRR DOES INDICATE THESE SHOWERS TO SORT OF OSCILLATE ALL THE WAY UP TO FAR NORTHEAST IL THROUGH EARLY OVERNIGHT. THE ILX VAD PROFILER INDICATES INCREASING SOUTHERLY FLOW BELOW 3K FT...NOW UP TO 30 KT. THE LOW-LEVEL JET IS NOT EXPECTED TO INCREASE MUCH FROM THAT MAGNITUDE AND POINT MORE INTO WESTERN IL. MOISTURE TRANSPORT IS MORE LIMITED TONIGHT SO NOT EXPECTING AS MUCH IF ANY ELEVATED CONVECTION...BUT COULD SEE SOME IN WESTERN IL WHERE A LITTLE MORE THETA-E ADVECTION AND CONVERGENCE AROUND 850MB IS FORECAST. THE LAKE BREEZE MADE IMPRESSIVE PROGRESS WSW THROUGH EARLY EVE AFTER SORT OF A SLOW START. A 30 DEGREE SPREAD AS OF 930 PM EXISTS ACROSS THE CWA SIMPLY FROM JUST THIS MESOSCALE BOUNDARY. HAVE ADJUSTED THE HOURLY TEMPERATURE FORECAST TO MEET TRENDS. THE LAV GUIDANCE HAS VERY LITTLE TEMPERATURE DROP FOR MANY POINTS THROUGH THE REST OF THE NIGHT...LIKELY DUE TO INCREASING CLOUD COVER. WHILE CAA OFF THE LAKE LIKELY WILL CREATE A LITTLE MORE DROP THAN IT ADVERTISES...THIS IS IN LINE WITH THE GOING MINIMUM TEMPERATURE FORECASTS. MTF && .PREV DISCUSSION... 259 PM CDT TODAY`S FORECAST CHALLENGES CONTINUE TO BE DEALING WITH FRONTAL BOUNDARY CURRENTLY JUST SOUTH OF THE CWA...AND PERIODIC CONVECTIVE CHANCES THROUGH MID NEXT WEEK. TODAY AND TONIGHT... THIS AFTERNOON THE FRONT IS LOCATED JUST NORTH OF QUINCY IL EAST TO NEAR TERRE HAUTE INDIANA...AND HAS BEEN SLOWLY PUSHING NORTH THIS AFTERNOON. MODERATE INSTABILITY EXISTS SOUTH OF THE FRONT AND MAY LIFT INTO FAR SOUTHERN PORTIONS OF THE CWA LATE THIS EVENING BEFORE FADING NOCTURNALLY. MAINTAINED SLT CHC POPS FOR A FEW HOURS THIS EVENING WHEN THIS OCCURS...BUT OTHERWISE SHOULD BE FAIRLY QUIET PERIOD THROUGH TONIGHT. FRIDAY THROUGH SATURDAY... COMPACT SHORTWAVE NOTED ON WV IMAGERY THIS AFTERNOON OVER WESTERN NE/KS WILL CONTINUE ENE INTO WEST CENTRAL WISCONSIN BY FRIDAY AFTERNOON. AS THIS HAPPENS...SOUTHERLY FLOW INCREASE AT THE SURFACE AND SHOULD HELP PUSH THE BOUNDARY NORTH ACROSS THE AREA. DEWPOINTS RISE INTO THE MID 60S AND MODEST INSTABILITY DEVELOPS OUTSIDE OF FAR NE ILLINOIS WHERE ONSHORE WINDS WILL KEEP CONDITIONS COOLER/MORE STABLE. THIS INSTABILITY IS UNCAPPED...AND GIVEN THERE IS NO WELL DEFINED FOCUS FOR THUNDERSTORMS...EXPECT UNORGANIZED/SCATTERED CONVECTION TO DEVELOP WITHIN THE WARM SECTOR. MID LEVEL LAPSE RATES ARE PRETTY POOR...SO CONVECTION MAY STRUGGLE AT TIMES AND MAY LIMIT THE THUNDER CHANCES TO SOME DEGREE. MUCH OF THE SAME IS EXPECTED SATURDAY SO WILL MAINTAIN THE LOW POPS FOR DIURNALLY DRIVEN TSTORMS. SUNDAY THROUGH TUESDAY... THIS PERIOD CONTINUES TO LOOK ACTIVE AS THE OVERALL PATTERN AMPLIFIES WITH DEEP TROUGHING DEVELOPING ACROSS THE WESTERN CONUS...AND STRONG RIDGING EAST. THE H85 THERMAL RIDGE BEGINS TO WORK INTO THE AREA SUNDAY...AS WELL AS DRY AIR ALOFT AND THE EML LATER IN THE DAY HELPING TO STEEPEN LAPSE RATES ALOFT. NEGATIVELY TILTED TROUGH IS EXPECTED TO ROUND THE BASE OF THE LONGWAVE TROUGH SUNDAY LIFTING INTO THE MID MISSOURI VALLEY SUNDAY NIGHT. MODELS ARE MIXED ON WHETHER OR NOT THE CIN ERODES DURING THE DAYTIME...BUT IF IT DOES CHANCES WILL BE BEST OVER WESTERN PORTIONS OF THE CWA...SO HAVE MAINTAINED LOWER POPS. THERE MAY BE A BETTER CHANCE FOR CONVECTION OVERNIGHT AS A LOW LEVEL JET DEVELOPS JUST TO OUR WEST WITH LARGE SCALE ASCENT ASSOCIATED WITH AFOREMENTIONED TROUGH. ON MONDAY...THE GFS INDICATES ANOTHER LOWER AMPLITUDE DISTURBANCE WILL ROUND THE BASE OF THE LONGWAVE TROUGH AND LIFT INTO THE MID MISSISSIPPI VALLEY. THIS CONTINUES TO BE A DAY TO KEEP AN EYE ON FOR SEVERE WEATHER POTENTIAL. MODELS CONTINUE TO ADVERTISE MODERATE TO STRONG INSTABILITY IN PLACE OVERHEAD WITH MARGINAL SHEAR CONDITIONS TO SUPPORT SEVERE WEATHER. AS PREVIOUSLY MENTIONED...CONVECTION FROM THE PREVIOUS NIGHT...CLOUD COVER...AND OTHER SMALL SCALE FEATURES CANNOT BE RESOLVED THIS FAR OUT AND ADD A CONSIDERABLE AMOUNT OF UNCERTAINTY. WE SHOULD BEGIN TO GET A BETTER PICTURE THIS WEEKEND SO STAY TUNED FOR FORECAST UPDATES. DEPENDING ON THE SPEED OF THE SYSTEM...TUESDAY WILL ALSO HAVE TO BE MONITORED...PERHAPS WITH THE THREAT MORE FOCUSED ON THE EASTERN PORTIONS OF THE CWA. IN ADDITION TO THE SEVERE THREAT...MULTIPLE ROUNDS OF THUNDERSTORMS MOVING ALONG THE SLOW MOVING BOUNDARY SUNDAY NIGHT THROUGH TUESDAY WILL LEAD TO A INCREASED HEAVY RAIN AND FLOODING THREAT. FOR TEMPERATURES SUNDAY AND MONDAY...CONTINUE TO LEAN ON THE WARMER BIAS CORRECTED GEM WHICH HAPPENED TO VERIFY BEST WITH THE UNSEASONABLY HEAT TUESDAY. DEPENDING ON THE SPEED OF THE SYSTEM...CURRENT FORECAST TEMPS MAY BE A BIT ON THE COOL SIDE TUESDAY...PARTICULARLY THE EASTERN CWA. H85 TEMPS OF 16-18C AND H92 TEMPS OF 19-22C SHOULD SUPPORT TEMPERATURES WELL INTO THE 80S AND WOULDN`T BE SURPRISED TO SEE PLACES HIT 90S THOSE DAYS...BUT WILL REMAIN A BIT CONSERVATIVE GIVEN THE PRECIP CHANCES AND CLOUD COVER. DEUBELBEISS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 00Z... * ENELY WINDS 5-10KT FOLLOWING LAKE BREEZE PASSAGE. * SELY WINDS TOMORROW MORNING BACKING ELY IN THE AFTERNOON. * CHANCE TSRA/SHRA TOMORROW AFTERNOON/EVENING. KREIN //DISCUSSION...UPDATED 00Z... THE LAKE BREEZE HAS FINALLY PUSHED INLAND OF ORD/MDW/GYY AND SHOULD PUSH THROUGH DPA SOON AS WELL. THIS WILL SET UP ENELY WINDS OVER NERN IL/NWRN IN...BUT WILL LIKELY NOT IMPACT RFD WHICH SHOULD REMAIN SELY THROUGH THE NIGHT. HAVE BEEN MONITORING THE PROGRESSION OF THE LAKE BREEZE BOUNDARY TO THE SOUTHWEST ALONG WITH ANOTHER WEAK BOUNDARY MOVING NORTHWARD ALONG THE ILLINOIS/KANKAKEE RIVERS. THIS WEAK BOUNDARY SEPARATES SOUTHERLY FLOW WITH SLIGHTLY HIGHER DEWPOINTS. WILL NEED TO MONITOR THESE BOUNDARYS CLOSELY AS THEY APPROACH EACH OTHER FOR ANY SHRA/TSRA DEVELOPMENT...WHICH BASED ON CURRENT TRACK/TIMING WOULD BE INVOF KJOT AREA. OTHERWISE THE REMAINDER OF THE NIGHT SHOULD BE QUIET AT THE TERMINALS. FOCUS WILL THEN SHIFT TO TSRA POTENTIAL TOMORROW AFTERNOON. LATEST GUIDANCE INDICATES A WARM FRONT LIFTING INTO NRN IL/IN BY LATE TOMORROW AFTERNOON. MOISTURE POOLING ALONG THE BOUNDARY AND ISENTROPIC LIFT ALONG THE FRONTAL ZONE WILL PROVIDE ENOUGH FOCUS TO NECESSATE ADDING A PROB30 GROUP TO THE FORECAST. TIMING WILL BE THE MAIN QUESTION...BUT GENERALLY EXPECT THE BEST TIMING TO BE DURG THE LATE AFTERNOON/EARLY EVENING HOURS. KREIN //ORD AND MDW CONFIDENCE...UPDATED 00Z... * MODERATE TO HIGH CONFIDENCE IN WIND TRENDS. * MODERATE CONFIDENCE IN TSRA/SHRA CHANCES TOMORROW...BUT LOWER CONFIDENCE IN EXACT TIMING. KREIN //OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z... SATURDAY THROUGH WEDNESDAY...PERIODIC CHANCES FOR SHRA/TSRA... OTHERWISE...VFR. KREIN && .MARINE... 228 PM CDT RIDGING FROM HIGH PRESSURE CENTERED OVER WESTERN ONTARIO EXTENDS ACROSS LAKE MICHIGAN THIS AFTERNOON. WEAK LOW PRESSURE WILL DEVELOP AND MOVE UP THE OHIO RIVER VALLEY FRIDAY WITH ADDITIONAL LOW PRESSURE DEVELOPING ACROSS THE CENTRAL HIGH PLAINS. EAST TO NORTHEAST FLOW OVERALL WILL CONTINUE ACROSS THE LAKE...WITH ONSHORE FLOW IN AREAS WHERE THE PRESSURE GRADIENT IS WEAKER CAUSING SOME ERRATIC DIRECTIONS AT TIMES. STEADIER AND MORE UNIFORM WINDS WILL DEVELOP WITH TIME THROUGH TOMORROW WITH MORE OF AN EAST TO SOUTHEAST TREND. THE STRONGEST WINDS WILL OCCUR FRIDAY EVENING/NIGHT COINCIDENT WITH THE STRONGEST PRESSURE GRADIENT THANKS TO THE LOW PASSING TO THE SOUTHEAST. THE GRADIENT WEAKENS DURING THE DAY SATURDAY AS THE LOW DEPARTS TO THE EAST. LOW PRESSURE STRENGTHENS ACROSS THE CENTRAL/NORTHERN HIGH PLAINS INTO SUNDAY WHICH WILL GRADUALLY TIGHTEN THE PRESSURE GRADIENT ACROSS THE LAKE. THIS WILL ALLOW A STEADY SOUTH TO SOUTHEAST WIND TO DEVELOP ACROSS MOST OF THE LAKE...WITH A MORE EASTERLY DIRECTION ACROSS THE FAR NORTH WHERE A WARM FRONTAL BOUNDARY IS EXPECTED TO SET UP. THE MAIN LOW WILL MEANDER NORTHWARD BEFORE BEING PUSHED EASTWARD ACROSS MINNESOTA/IOWA SOMETIME TUESDAY OR WEDNESDAY WHICH WILL LIKELY PUSH THE FRONTAL BOUNDARY FURTHER SOUTH ACROSS THE LAKE LEADING TO EAST TO NORTHEAST WINDS NORTH AND SOUTH TO SOUTHWEST WINDS SOUTH BY MID WEEK. THE MAIN CONCERN WILL BE THE POTENTIAL FOR INCREASED GUSTINESS ACROSS THE NORTH AS COLDER AIR SETTLES IN ALLOWING SLIGHTLY INCREASED MIXING. OTHERWISE...GENERALLY STABLE LOW LEVEL AIR ACROSS THE LAKE WILL KEEP GUSTS TO A MINIMUM FROM TONIGHT THROUGH THE WEEKEND. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS LINCOLN IL
743 PM CDT THU MAY 16 2013 .DISCUSSION... ISSUED 743 PM CDT THU MAY 16 2013 SYNOPTIC FRONTAL BOUNDARY HAS LIFTED NORTHWARD TO NEAR THE I-74 CORRIDOR EARLY THIS EVENING. DEWPOINTS TO THE SOUTH OF THE BOUNDARY ARE IN THE UPPER 50S AND LOWER 60S ACROSS MUCH OF THE KILX CWA...WHILE DEWPOINTS NORTH OF THE FRONT ARE ONLY IN THE 40S ACROSS NORTHERN ILLINOIS. MESOSCALE OUTFLOW BOUNDARY FROM CONVECTION EARLIER TODAY FROM NEAR SPRINGFIELD S/SE TO LAWRENCEVILLE HAS LIFTED NORTHWARD AS WELL...RESULTING IN A RELATIVELY STABLE AIRMASS ACROSS THE AREA. BEST INSTABILITY AND LIFT IS CURRENTLY FOCUSED ALONG/NORTH OF THE FRONTAL BOUNDARY ACROSS THE FAR NORTHERN CWA. A FEW SHOWERS HAVE DEVELOPED ACROSS WOODFORD AND NORTHERN MCLEAN COUNTIES OVER THE PAST HOUR...AND THIS AREA WILL HAVE TO BE MONITORED FOR ADDITIONAL DEVELOPMENT AS THE EVENING PROGRESSES. WILL MAINTAIN SLIGHT CHANCE POPS EVERYWHERE DURING THE EVENING...THEN WILL LIMIT POPS TO ONLY THE NORTHERN CWA IN CLOSER PROXIMITY TO THE FRONT OVERNIGHT. ZONE UPDATE HAS ALREADY BEEN SENT. BARNES && .AVIATION... ISSUED 635 PM CDT THU MAY 16 2013 MAIN AVIATION FORECAST CHALLENGE WILL BE TRYING TO PINPOINT TIMING OF POTENTIAL CONVECTION OVER THE NEXT 24 HOURS. MESOSCALE OUTFLOW BOUNDARY FROM STORMS ACROSS SOUTH-CENTRAL/SOUTHEAST ILLINOIS EARLIER TODAY HAS DRIFTED NORTH OF THE I-74 TERMINALS...RESULTING IN A RATHER STABLE ENVIRONMENT ACROSS MUCH OF CENTRAL ILLINOIS EARLY THIS EVENING. WILL HAVE TO KEEP AN EYE ON A CU-FIELD ALONG THE DISSIPATING OUTFLOW JUST NORTH OF KPIA AND KBMI...AS 21Z HRRR TRIES TO FIRE SCATTERED STORMS IN THIS GENERAL AREA AFTER 03Z. AT THIS POINT...WILL LEAVE THUNDER MENTION OUT OF THE TAFS THROUGH TONIGHT. UPPER LOW CURRENTLY SPINNING OVER THE OZARKS WILL PIVOT NORTHEASTWARD ON FRIDAY...SPREADING DEEPER MOISTURE NORTHWARD INTO THE AREA. WILL THEREFORE INTRODUCE VCTS AT KSPI AND KDEC AFTER 14Z...THEN FURTHER NORTH INTO KPIA BY 17Z. WINDS WILL INITIALLY BE FROM THE S/SW...THEN WILL BACK TO SE BY MID TO LATE EVENING. WITH LIGHT WINDS EXPECTED OVERNIGHT...FORECAST SOUNDINGS ARE SUGGESTING THE POTENTIAL FOR FOG DEVELOPMENT. WILL REDUCE VISBYS TO BETWEEN 4 AND 5SM AFTER 07Z ACCORDINGLY. BARNES && .PREV DISCUSSION... ISSUED 300 PM CDT THU MAY 16 2013 A STATIONARY FRONT WILL OSCILLATE NORTH AND SOUTH ACROSS ILLINOIS OVER THE NEXT DAY AND A HALF...THEN THE FRONT SHOULD LIFT NORTH AS A WARM FRONT FOR THE WEEKEND...PUSHING HIGHS INTO THE MID TO UPPER 80S BY SUNDAY. BANDS OF THUNDERSTORMS THAT DEVELOP THROUGH TOMORROW WILL LIKELY BE SLOW MOVING, HEAVY RAIN PRODUCERS LIKE TODAY`S STORMS. LOCALIZED AREAS COULD SEE SIGNIFICANT RAINFALL OF 2-3 INCHES IN A COUPLE HOURS WHILE NEARBY AREAS SEE LITTLE RAIN. PINPOINTING THAT ACTIVITY WILL BE DIFFICULT...BUT DIURNAL TRENDS SHOULD PUT MOST OF THE CONVECTION DURING THE AFTERNOON TOMORROW...ESPECIALLY NEAR ANY OUTFLOW BOUNDARIES SET DOWN BY TODAY`S STORMS. A SLIGHT LULL IN STORMS SHOULD OCCUR THIS WEEKEND AS RIDGING IN THE PLAINS BUILDS INTO IL. A STRONGER COLD FRONT IS EXPECTED TO PUSH ACROSS IL ON MONDAY AND MONDAY NIGHT...BRINGING OUR BETTER CHANCES OF THUNDERSTORMS. WE ARE IN THE SPC DAY 5 OUTLOOK FOR STRONG TO SEVERE STORMS MON-MON NIGHT. A COOL DOWN IS PROJECTED FOR TUES THROUGH THURSDAY BEHIND THE COLD FRONT...PULLING HIGHS BACK INTO THE 70S...BUT STILL AT OR ABOVE NORMAL. SHORT TERM...TONIGHT THROUGH SUNDAY. SHOWERS AND STORMS WILL GENERALLY BE DIMINISHING AS WE HEAD INTO THE EVENING. THE LINE OF CONVECTION MAINLY CENTERED ON A LINE FROM RUSHVILLE TO TAYLORVILLE TO EFFINGHAM TO LAWRENCEVILLE...IS EXPECTED TO LIFT NORTH THIS EVENING. THE RAP MODEL IS SHOWING THE INSTABILITY AXIS FOLLOWING THE SAME PROGRESSION...WITH SOME SHOWER ACTIVITY DEVELOPING DURING THAT TIME. IN THE LAST HOUR...PRECIP COVERAGE AND UPDRAFT INTENSITY HAVE ALREADY BEGUN DIMINISHING OR WEAKENING RESPECTIVELY. RADAR LOOPS SHOW VARIOUS OUTFLOW BOUNDARIES MOVING NORTH ACROSS OUR COUNTIES...AND MAY END UP BEING A FOCUS FOR EVENING SHOWERS ALONG AND NORTH OF I-72. STILL...COVERAGE WILL BE ISOLATED IN GENERAL. FRIDAY MORNING...THE LOCATION OF THE BEST INSTABILITY WILL BE ALONG AND NORTH OF I-74...SO ANY MORNING CONVECTION ON FRIDAY MAY BE FOCUSED IN THAT AREA. DURING THE AFTERNOON...AN UPPER LOW PRESSURE WAVE IS FORECAST TO LIFT NORTHEAST ACROSS IL...IN CONCERT WITH INCREASING MOISTURE AND INSTABILITY AS THE STATIONARY FRONT OSCILLATES NORTHWARD WITH THE WAVE. COVERAGE OF STORMS SHOULD BE MORE THAN TODAY...BASED ON THE SUPPORT OF THE UPPER WAVE AND JET DYNAMICS. ANY SUNSHINE THAT HEATS UP THE BOUNDARY LAYER WILL HELP TO CREATE A FEW STRONG UPDRAFTS WITH SMALL HAIL, GUSTY WINDS, AND VERY HEAVY RAINFALL. THE STORMS MAY LINGER INTO THE EVENING EAST OF I-57...BUT SHOULD DIMINISH BY MIDNIGHT. BY 12Z SAT MORNING...THE UPPER LOW IS FORECAST TO BE CENTERED IN SOUTHERN INDIANA...WHICH WILL HELP PUT PRECIP CHANCES MAINLY IN OUR SOUTHEAST COUNTIES ALONG AND SOUTHEAST OF A LINE FROM SHELBYVILLE TO PARIS. THE SLOW DEPARTURE OF THE LOW WILL KEEP CHANCES OF SHOWERS AND STORMS THROUGH SATURDAY AFTERNOON IN THE SOUTHEAST. THE WARM FRONT DEPARTING INTO NORTHERN IL FOLLOWED BY RIDGING AT THE SURFACE AND ALOFT SATURDAY NIGHT AND SUNDAY SHOULD HELP MAKE MOST AREAS DRY FOR THE LAST HALF OF THE WEEKEND. THE ADDITIONAL SUNSHINE ON SUNDAY ALONG WITH DEEPER WARM AIR WILL HELP PUSH HIGH TEMPS INTO THE MID TO UPPER 80S...WITH MUGGY DEWPOINTS IN THE UPPER 60S TO NEAR 70. HEAT INDEX READINGS SUNDAY AFTERNOON WILL CLIMB INTO THE 90S. LONG TERM...MONDAY THROUGH THURSDAY. ON MONDAY...AN OCCLUDING LOW PRESSURE PRESSURE SYSTEM IN THE EASTERN DAKOTAS WILL CREATE SOME WARM FRONTOGENESIS TO THE SOUTHEAST OF THE LOW ACROSS OUR NORTHERN COUNTIES. THAT WILL CREATE A FOCUS FOR CONVECTION BY MONDAY AFTERNOON. MONDAY NIGHT...A COLD FRONT WILL MOVE ACROSS IL PRODUCING STRONG TO SEVERE STORMS AS ML-CAPE VALUES CLIMB TO NEAR 2K J/KG. BULK SHEAR IS EXPECTED TO REACH OVER 40KT AS WELL...SO EMBEDDED SUPERCELLS WILL BE POSSIBLE IN THE LINE OF STORMS THAT MOVES THROUGH. STORMS ARE EXPECTED TO LINGER INTO TUESDAY AS THE UPPER COLD POOL SLOWLY MAKES PROGRESS INTO ILLINOIS. WE KEPT LIKELY POPS SOUTHEAST OF I-72...AND CHANCE ELSEWHERE. TUESDAY NIGHT PRECIP COVERAGE SHOULD DIMINISH...WITH CHANCE POPS STILL IN PLACE ACROSS THE BOARD. AN ELONGATED SURFACE TROUGH IS PROJECTED TO LINGER ACROSS NORTHERN ILLINOIS INTO WED AS THE OCCLUDED UPPER LOW BECOMES MORE OF AN OPEN WAVE AND SEND A SURFACE LOW EASTWARD ACROSS WISCONSIN. THAT PROGRESSION WILL KEEP SCATTERED SHOWERS POSSIBLE AS FAR SOUTH AS CENTRAL ILLINOIS THROUGH THURSDAY...ESPECIALLY EAST OF I-55. PRECIP AMOUNTS MID WEEK SHOULD REMAIN LIGHT...BUT STILL CLOUDS AND COOLER AIR WILL KEEP HIGH TEMPS BACK IN THE 70S...CLOSER TO NORMAL. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
635 PM CDT THU MAY 16 2013 .DISCUSSION... ISSUED 300 PM CDT THU MAY 16 2013 A STATIONARY FRONT WILL OSCILLATE NORTH AND SOUTH ACROSS ILLINOIS OVER THE NEXT DAY AND A HALF...THEN THE FRONT SHOULD LIFT NORTH AS A WARM FRONT FOR THE WEEKEND...PUSHING HIGHS INTO THE MID TO UPPER 80S BY SUNDAY. BANDS OF THUNDERSTORMS THAT DEVELOP THROUGH TOMORROW WILL LIKELY BE SLOW MOVING, HEAVY RAIN PRODUCERS LIKE TODAY`S STORMS. LOCALIZED AREAS COULD SEE SIGNIFICANT RAINFALL OF 2-3 INCHES IN A COUPLE HOURS WHILE NEARBY AREAS SEE LITTLE RAIN. PINPOINTING THAT ACTIVITY WILL BE DIFFICULT...BUT DIURNAL TRENDS SHOULD PUT MOST OF THE CONVECTION DURING THE AFTERNOON TOMORROW...ESPECIALLY NEAR ANY OUTFLOW BOUNDARIES SET DOWN BY TODAY`S STORMS. A SLIGHT LULL IN STORMS SHOULD OCCUR THIS WEEKEND AS RIDGING IN THE PLAINS BUILDS INTO IL. A STRONGER COLD FRONT IS EXPECTED TO PUSH ACROSS IL ON MONDAY AND MONDAY NIGHT...BRINGING OUR BETTER CHANCES OF THUNDERSTORMS. WE ARE IN THE SPC DAY 5 OUTLOOK FOR STRONG TO SEVERE STORMS MON-MON NIGHT. A COOL DOWN IS PROJECTED FOR TUES THROUGH THURSDAY BEHIND THE COLD FRONT...PULLING HIGHS BACK INTO THE 70S...BUT STILL AT OR ABOVE NORMAL. SHORT TERM...TONIGHT THROUGH SUNDAY. SHOWERS AND STORMS WILL GENERALLY BE DIMINISHING AS WE HEAD INTO THE EVENING. THE LINE OF CONVECTION MAINLY CENTERED ON A LINE FROM RUSHVILLE TO TAYLORVILLE TO EFFINGHAM TO LAWRENCEVILLE...IS EXPECTED TO LIFT NORTH THIS EVENING. THE RAP MODEL IS SHOWING THE INSTABILITY AXIS FOLLOWING THE SAME PROGRESSION...WITH SOME SHOWER ACTIVITY DEVELOPING DURING THAT TIME. IN THE LAST HOUR...PRECIP COVERAGE AND UPDRAFT INTENSITY HAVE ALREADY BEGUN DIMINISHING OR WEAKENING RESPECTIVELY. RADAR LOOPS SHOW VARIOUS OUTFLOW BOUNDARIES MOVING NORTH ACROSS OUR COUNTIES...AND MAY END UP BEING A FOCUS FOR EVENING SHOWERS ALONG AND NORTH OF I-72. STILL...COVERAGE WILL BE ISOLATED IN GENERAL. FRIDAY MORNING...THE LOCATION OF THE BEST INSTABILITY WILL BE ALONG AND NORTH OF I-74...SO ANY MORNING CONVECTION ON FRIDAY MAY BE FOCUSED IN THAT AREA. DURING THE AFTERNOON...AN UPPER LOW PRESSURE WAVE IS FORECAST TO LIFT NORTHEAST ACROSS IL...IN CONCERT WITH INCREASING MOISTURE AND INSTABILITY AS THE STATIONARY FRONT OSCILLATES NORTHWARD WITH THE WAVE. COVERAGE OF STORMS SHOULD BE MORE THAN TODAY...BASED ON THE SUPPORT OF THE UPPER WAVE AND JET DYNAMICS. ANY SUNSHINE THAT HEATS UP THE BOUNDARY LAYER WILL HELP TO CREATE A FEW STRONG UPDRAFTS WITH SMALL HAIL, GUSTY WINDS, AND VERY HEAVY RAINFALL. THE STORMS MAY LINGER INTO THE EVENING EAST OF I-57...BUT SHOULD DIMINISH BY MIDNIGHT. BY 12Z SAT MORNING...THE UPPER LOW IS FORECAST TO BE CENTERED IN SOUTHERN INDIANA...WHICH WILL HELP PUT PRECIP CHANCES MAINLY IN OUR SOUTHEAST COUNTIES ALONG AND SOUTHEAST OF A LINE FROM SHELBYVILLE TO PARIS. THE SLOW DEPARTURE OF THE LOW WILL KEEP CHANCES OF SHOWERS AND STORMS THROUGH SATURDAY AFTERNOON IN THE SOUTHEAST. THE WARM FRONT DEPARTING INTO NORTHERN IL FOLLOWED BY RIDGING AT THE SURFACE AND ALOFT SATURDAY NIGHT AND SUNDAY SHOULD HELP MAKE MOST AREAS DRY FOR THE LAST HALF OF THE WEEKEND. THE ADDITIONAL SUNSHINE ON SUNDAY ALONG WITH DEEPER WARM AIR WILL HELP PUSH HIGH TEMPS INTO THE MID TO UPPER 80S...WITH MUGGY DEWPOINTS IN THE UPPER 60S TO NEAR 70. HEAT INDEX READINGS SUNDAY AFTERNOON WILL CLIMB INTO THE 90S. LONG TERM...MONDAY THROUGH THURSDAY. ON MONDAY...AN OCCLUDING LOW PRESSURE PRESSURE SYSTEM IN THE EASTERN DAKOTAS WILL CREATE SOME WARM FRONTOGENESIS TO THE SOUTHEAST OF THE LOW ACROSS OUR NORTHERN COUNTIES. THAT WILL CREATE A FOCUS FOR CONVECTION BY MONDAY AFTERNOON. MONDAY NIGHT...A COLD FRONT WILL MOVE ACROSS IL PRODUCING STRONG TO SEVERE STORMS AS ML-CAPE VALUES CLIMB TO NEAR 2K J/KG. BULK SHEAR IS EXPECTED TO REACH OVER 40KT AS WELL...SO EMBEDDED SUPERCELLS WILL BE POSSIBLE IN THE LINE OF STORMS THAT MOVES THROUGH. STORMS ARE EXPECTED TO LINGER INTO TUESDAY AS THE UPPER COLD POOL SLOWLY MAKES PROGRESS INTO ILLINOIS. WE KEPT LIKELY POPS SOUTHEAST OF I-72...AND CHANCE ELSEWHERE. TUESDAY NIGHT PRECIP COVERAGE SHOULD DIMINISH...WITH CHANCE POPS STILL IN PLACE ACROSS THE BOARD. AN ELONGATED SURFACE TROUGH IS PROJECTED TO LINGER ACROSS NORTHERN ILLINOIS INTO WED AS THE OCCLUDED UPPER LOW BECOMES MORE OF AN OPEN WAVE AND SEND A SURFACE LOW EASTWARD ACROSS WISCONSIN. THAT PROGRESSION WILL KEEP SCATTERED SHOWERS POSSIBLE AS FAR SOUTH AS CENTRAL ILLINOIS THROUGH THURSDAY...ESPECIALLY EAST OF I-55. PRECIP AMOUNTS MID WEEK SHOULD REMAIN LIGHT...BUT STILL CLOUDS AND COOLER AIR WILL KEEP HIGH TEMPS BACK IN THE 70S...CLOSER TO NORMAL. && .AVIATION... ISSUED 635 PM CDT THU MAY 16 2013 MAIN AVIATION FORECAST CHALLENGE WILL BE TRYING TO PINPOINT TIMING OF POTENTIAL CONVECTION OVER THE NEXT 24 HOURS. MESOSCALE OUTFLOW BOUNDARY FROM STORMS ACROSS SOUTH-CENTRAL/SOUTHEAST ILLINOIS EARLIER TODAY HAS DRIFTED NORTH OF THE I-74 TERMINALS...RESULTING IN A RATHER STABLE ENVIRONMENT ACROSS MUCH OF CENTRAL ILLINOIS EARLY THIS EVENING. WILL HAVE TO KEEP AN EYE ON A CU-FIELD ALONG THE DISSIPATING OUTFLOW JUST NORTH OF KPIA AND KBMI...AS 21Z HRRR TRIES TO FIRE SCATTERED STORMS IN THIS GENERAL AREA AFTER 03Z. AT THIS POINT...WILL LEAVE THUNDER MENTION OUT OF THE TAFS THROUGH TONIGHT. UPPER LOW CURRENTLY SPINNING OVER THE OZARKS WILL PIVOT NORTHEASTWARD ON FRIDAY...SPREADING DEEPER MOISTURE NORTHWARD INTO THE AREA. WILL THEREFORE INTRODUCE VCTS AT KSPI AND KDEC AFTER 14Z...THEN FURTHER NORTH INTO KPIA BY 17Z. WINDS WILL INITIALLY BE FROM THE S/SW...THEN WILL BACK TO SE BY MID TO LATE EVENING. WITH LIGHT WINDS EXPECTED OVERNIGHT...FORECAST SOUNDINGS ARE SUGGESTING THE POTENTIAL FOR FOG DEVELOPMENT. WILL REDUCE VISBYS TO BETWEEN 4 AND 5SM AFTER 07Z ACCORDINGLY. BARNES && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
711 PM EDT THU MAY 16 2013 .SYNOPSIS... ISSUED AT 655 PM EDT THU MAY 16 2013 A FRONTAL BOUNDARY WHICH HAS BROUGHT SHOWERS AND THUNDERSTORMS TO PORTIONS OF SOUTHERN INDIANA AND OHIO TODAY WILL BEGIN TO SHIFT NORTH BY FRIDAY AFTERNOON WHICH WILL BRING A LOW CHANCE OF SHOWERS AND THUNDERSTORMS TO AREAS SOUTH OF US 30. SHOWER AND THUNDERSTORM CHANCES WILL PERSIST THROUGH THE WEEKEND AS THE FRONTAL BOUNDARY REMAINS ACROSS THE AREA. ABOVE NORMAL TEMPERATURES ARE EXPECTED LATE THIS WEEK INTO THIS WEEKEND. CHANCES FOR SHOWERS AND THUNDERSTORMS INCREASE EARLY NEXT WEEK AS A STORM SYSTEM APPROACHES FROM THE WEST. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) HIGH PRESSURE HAS KEPT BULK OF MSTR JUST FAR ENOUGH SOUTH OF THE AREA TODAY TO ALLOW FOR GENERALLY DRY CONDITIONS AND TEMPS MOVING WELL THROUGH THE 70S IN MOST SPOTS. A FEW LIGHT SHOWERS/SPRINKLES WERE NOTED ALONG FIRST OF 2 SFC THETA E GRADIENTS ACROSS FAR SOUTHERN COUNTIES. THIS AREA IS EXPECTED TO SHIFT SOUTH OVER THE NEXT SEVERAL HOURS AND REMOVE ANY CHANCE FOR PRECIP FOR THE REMAINDER OF THE NIGHT. SECONDARY GRADIENT WAS LOCATED FURTHER SOUTH ACROSS SOUTHERN INDIANA WHERE CONVECTION HAS BEEN ONGOING MUCH OF THE DAY. MODELS TEND TO SUGGEST THAT THIS SECONDARY AREA OF MSTR/GREATER LIFT SUPPORT WITH MAIN SFC BOUNDARY WILL BRING INCREASING CHANCES FOR SHOWERS AND STORMS ON FRIDAY. IT WOULD APPEAR THAT MOST FAVORABLE TIMING WOULD BE MID TO LATE AFTERNOON FRIDAY IN FAR SW SECTIONS WITH PROGRESSION NE HAMPERED SOMEWHAT BY DRY AIR/SEMI DRY GROUND CONDITIONS. IF NEW RUN OF SPC 4KM WRF IS FOLLOWED...CONVECTION WOULD NOT ARRIVE UNTIL AFTER 00Z SAT. HAVE ADJUSTED GRIDS TO REFLECT THIS WITH SLGT CHC TO CHC POPS CONFINED TO AFTERNOON. CLOUD COVER WILL BE ON THE INCREASE...WHICH WILL BUT A DAMPER ON POTENTIAL CLIMB IN HIGHS. THAT BEING SAID...HIGHS SHOULD STILL END UP ABOVE NORMAL CLIMBING INTO THE MID AND UPPER 70S. && .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) WATER VAPOR IMAGERY AND LATEST RAP ANALYSIS THAT IS DEPICTING MID LEVEL CIRCULATION MOVING EASTWARD ACROSS THE SOUTHERN PLAINS THIS AFTERNOON WILL HAVE AN IMPACT ON THE BEGINNING OF THE EXTENDED FCST PERIOD AS IT MOVES ACROSS THE TN VALLEY. THIS WILL ACT ON STATIONARY SFC BOUNDARY IN ADVECTING MOISTURE IN AN OVERRUNNING FASHION BACK NORTH OF THE BOUNDARY AND LEND SUPPORT TO WIDELY SCATTERED CONVECTION OVER THE SW HALF OF THE CWA. FOCUS WILL THEN SHIFT TO AMPLIFICATION OF THE UPPER LEVEL PATTERN AS STRONG JET DYNAMICS CURRENTLY WELL OUT IN THE PACIFIC ARE PROGGED BY MEDIUM RANGE MODELS TO COME ONSHORE AND DEVELOP DEEP UPPER TROF OVER THE WESTERN US. THIS WILL INDUCE DOWNSTREAM RIDGING THAT WILL BUILD INTO THE REGION SUN/MON BRINGING WARMER AND MAINLY DRY CONDITIONS TO THE AREA. WESTERN CONUS UPPER TROF THEN EXPECTED TO BECOME VERTICALLY STACKED CLOSED SYSTEM IN THE NORTHERN PLAINS WHICH MODELS ARE STRUGGLING WITH TIMING OF THE EVENTUAL EJECTION OF THIS SYSTEM INTO OUR AREA. AS EXPECTED OVERALL TREND CONTINUES TO BE SLOWER WITH ARRIVAL OF MAIN SYSTEM NOW DELAYED TO TUE/WED TIMEFRAME AND BRINGING WITH IT THE BEST CHANCES FOR PRECIP. PRIOR TO ITS ARRIVAL...BECOMING MORE AND MORE DIFFICULT TO PICK OUT MODELS HANDLING OF INCREASINGLY DIFFUSE SFC BOUNDARY BUT INDICATIONS ARE BOUNDARY WILL LIFT NORTH OF THE AREA IN CONJUNCTION WITH UPPER RIDGE MOVING OVER THE AREA WHICH SHOULD LEAVE MUCH OF THE FORECAST AREA IN A CAPPED WARM SECTOR SUN/MON. LOW CONFIDENCE IN ANY ONE PARTICULAR SCENARIO WITH THIS SETUP BUT WILL STILL INJECT A PERIOD OR TWO OF DRY WEATHER TO REFLECT THIS. ANTICIPATE TEMPS WELL INTO THE 80S ON MONDAY DEPENDING ON AMOUNT OF SUN...BUMPED ALLBLEND UP A DEGREE TO START UPWARD TREND. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING) ISSUED AT 707 PM EDT THU MAY 16 2013 DRY AIRMASS REMAINS OVER NORTHERN INDIANA THIS EVE AND WILL PERSIST THROUGH THE NIGHT ENSURING VFR CONDITIONS CONTG WITH NO LOW CLOUDS OR VSBY OBSCURATION. LOW PRESSURE OVER THE SRN PLAINS IS EXPECTED TO LIFT SLOWLY NE OVER THE NEXT 24HRS. THIS SHOULD RESULT IN SFC WINDS VEERING TO SE BY FRI AFTN. SOME POTENTIAL FOR AFTN SHRA/TS BUT MODELS DIFFER CONSIDERABLY IN AMOUNT OF MOISTURE/INSTABILITY THAT WILL RETURN TO THE AREA AND IN EITHER CASE BEST CHANCES SW OF THE TERMINALS SO HAVE NOT INCLUDED CONVECTION IN TAFS... BUT DID FCST CU FIELD IN THE AFTN. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...BENTLEY SHORT TERM...FISHER LONG TERM...JAL AVIATION...JT VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1212 PM CDT WED MAY 15 2013 .SHORT TERM.../TODAY /... ISSUED AT 359 AM CDT WED MAY 15 2013 SURFACE HIGH PRESSURE WILL MOVE INTO THE STATE TODAY AND WILL PROVIDE A MUCH QUIETER DAY ACROSS THE FORECAST AREA. THERE IS A SMALL POTENTIAL FOR SOME VERY HIGH BASED SHOWERS AND A STRAY THUNDERSTORM ACROSS NORTHERN IOWA THIS MORNING...DUE TO SOME WEAK THETA-E ADVECTION AND FORCING BETWEEN 700-500MB. HRRR HAS THE ISOLATED SHOWERS THROUGH 18Z...BUT 00Z NMM WRF DIMINISHING THE SHOWER ACTIVITY BEFORE ENTERING THE STATE. LEANED TOWARD THE HRRR AS IT SEEMED TO HAVE A DECENT GRASP ON CURRENT RADAR TRENDS. WEAK BOUNDARY ACROSS SOUTHERN IOWA LOOKS TO BE A FOCAL POINT FOR SOME ISOLATED THUNDERSTORMS THIS AFTERNOON. AGAIN...VERY HIGH BASED AS VERY MINIMAL MOISTURE BELOW 700MB. MAX TEMPS TODAY A LITTLE TRICK AS THINK GUIDANCE IS TOO LOW AGAIN AND FELT CONFIDENT ENOUGH TO TWEAK TEMPS UP TODAY...ESPECIALLY ACROSS THE SOUTH WHERE THE COOLER AIR DOES NOT REACH THIS AREA UNTIL THE AFTERNOON. WENT ABOVE GUIDANCE ACROSS THE CENTRAL TO SOUTHERN PORTIONS OF THE FORECAST AREA...WHICH WAS FAIRLY CLOSE TO THE MAV MOS GUIDANCE. IN NORTHERN IOWA WENT CLOSER THE THE NAM/MET MOS GUIDANCE FOR MAX TEMPS. .LONG TERM.../TONIGHT THROUGH TUESDAY/... ISSUED AT 359 AM CDT WED MAY 15 2013 RELATIVELY ACTIVE PERIOD THROUGH THE EXTENDED. HIGH PRESSURE WILL GRADUALLY DEPART TONIGHT INTO THURSDAY AND AS IT DOES...A STALLED FRONTAL BOUNDARY OVER NORTHERN MISSOURI WILL BEGIN TO LIFT BACK NORTH INTO IOWA. AS THIS OCCURS...A PLUME OF MOISTURE LIFTING THROUGH OKLAHOMA AND KANSAS WILL ARRIVE INTO SRN IA. THIS WILL BRING BACK THE CHANCE FOR THUNDERSTORMS IN THAT REGION. A STRONG PV ANOMALY OVER SRN NEVADA WILL APPROACH IA LATE THURSDAY AND THURSDAY NIGHT. PREFER THE FARTHER NORTH NAM/ECMWF SOLUTION OVER THE LESS ORGANIZED AND FARTHER SOUTH GFS. THIS WOULD PLACE THE FOCUS FOR ADDITIONAL THUNDERSTORMS OVER NORTHWEST AND NORTH CENTRAL IOWA. THIS POPS CONTINUE INTO FRIDAY MAINLY OVER THE NORTH. EXPECT AT THIS POINT THAT POPS MAY BE OVERDONE FOR FRIDAY. HAVE BEGUN TO TRIM BACK OVER THE CENTRAL AND SOUTH BUT IT MAY VERY WELL BE MOSTLY DRY MOST LOCATIONS. THE SAME CAN BE SAID FOR FRIDAY NIGHT WHERE POPS HAVE BEEN DROPPED FOR ALL BUT THE FAR NORTHEAST. IOWA WILL BE IN THE WARM SECTOR ON SATURDAY AND WHILE LOW POPS REMAIN...THE CONVECTIVE INHIBITION SHOULD HOLD STRONG MUCH OF THE DAY. THE PRECIPITATION CHANCES THROUGH THE REMAINDER OF THE PERIOD ARE MORE COMPLEX. THE INITIAL WAVE TO MOVE INTO THE INTER MOUNTAIN WEST WILL BE FOLLOWED BY ANOTHER INTENSE PIECE OF ENERGY SATURDAY NIGHT INTO SUNDAY. LONG RANGE GUIDANCE IS BEGINNING TO FAVOR THE TWO TO MERGE AND FORM A CLOSED LOW TO THE WEST/NORTHWEST OF THE AREA. THE FIRST WAVE WILL NUDGE THE UPPER LEVEL RIDGE ENOUGH EAST SATURDAY NIGHT TO BRING A RETURN FOR PRECIPITATION CHANCES...MAINLY OVER THE NORTH HOWEVER THE EVOLUTION TO A CLOSE LOW WILL SLOW THE BOUNDARY ARRIVAL TO LATER SUNDAY INTO MONDAY. INCREASING SOUTHWEST FLOW OVER THE STATE WILL KEEP THE PERIOD ACTIVE AND EVENTUALLY SHOULD BRING A SEVERE WEATHER THREAT TO THE STATE. TEMPERATURES THROUGH THE PERIOD WILL GENERALLY BE ABOVE SEASONAL VALUES. COOLER ACROSS THE SOUTH ON THURSDAY DUE TO ENHANCED CLOUD COVER THEN WARMER AGAIN FRIDAY INTO SATURDAY. && .AVIATION...15/18Z ISSUED AT 1209 PM CDT WED MAY 15 2013 CEILINGS WILL REMAIN VFR FOR PERIOD AT SITES WITH HIGH PRESSURE BUILDING IN. WINDS WILL BE GUSTY IN THE AFTERNOON WITH MIXING...BUT WILL REMAIN BELOW 20KTS. BOUNDARY NEAR SOUTHERN IOWA WILL BE FOCUS FOR ISOLATED RA/TSRA DEVELOPMENT IN THE AFTERNOON. MAY SEE SOME TSRA AT SOUTHERN SITES...KDMS/KOTM...BUT HAVE NOT INCLUDED MENTION ATTM WITH SCATTERED NATURE OF RA. WINDS WILL DECREASE AFTER 00Z...BECOMING MORE EASTERLY. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...PODRAZIK LONG TERM...DONAVON AVIATION...AWB
AREA FORECAST DISCUSSION
NWS DES MOINES IA
614 AM CDT WED MAY 15 2013 ...UPDATED AVIATION DISCUSSION... .SHORT TERM.../TODAY /... ISSUED AT 359 AM CDT WED MAY 15 2013 SURFACE HIGH PRESSURE WILL MOVE INTO THE STATE TODAY AND WILL PROVIDE A MUCH QUIETER DAY ACROSS THE FORECAST AREA. THERE IS A SMALL POTENTIAL FOR SOME VERY HIGH BASED SHOWERS AND A STRAY THUNDERSTORM ACROSS NORTHERN IOWA THIS MORNING...DUE TO SOME WEAK THETA-E ADVECTION AND FORCING BETWEEN 700-500MB. HRRR HAS THE ISOLATED SHOWERS THROUGH 18Z...BUT 00Z NMM WRF DIMINISHING THE SHOWER ACTIVITY BEFORE ENTERING THE STATE. LEANED TOWARD THE HRRR AS IT SEEMED TO HAVE A DECENT GRASP ON CURRENT RADAR TRENDS. WEAK BOUNDARY ACROSS SOUTHERN IOWA LOOKS TO BE A FOCAL POINT FOR SOME ISOLATED THUNDERSTORMS THIS AFTERNOON. AGAIN...VERY HIGH BASED AS VERY MINIMAL MOISTURE BELOW 700MB. MAX TEMPS TODAY A LITTLE TRICK AS THINK GUIDANCE IS TOO LOW AGAIN AND FELT CONFIDENT ENOUGH TO TWEAK TEMPS UP TODAY...ESPECIALLY ACROSS THE SOUTH WHERE THE COOLER AIR DOES NOT REACH THIS AREA UNTIL THE AFTERNOON. WENT ABOVE GUIDANCE ACROSS THE CENTRAL TO SOUTHERN PORTIONS OF THE FORECAST AREA...WHICH WAS FAIRLY CLOSE TO THE MAV MOS GUIDANCE. IN NORTHERN IOWA WENT CLOSER THE THE NAM/MET MOS GUIDANCE FOR MAX TEMPS. .LONG TERM.../TONIGHT THROUGH TUESDAY/... ISSUED AT 359 AM CDT WED MAY 15 2013 RELATIVELY ACTIVE PERIOD THROUGH THE EXTENDED. HIGH PRESSURE WILL GRADUALLY DEPART TONIGHT INTO THURSDAY AND AS IT DOES...A STALLED FRONTAL BOUNDARY OVER NORTHERN MISSOURI WILL BEGIN TO LIFT BACK NORTH INTO IOWA. AS THIS OCCURS...A PLUME OF MOISTURE LIFTING THROUGH OKLAHOMA AND KANSAS WILL ARRIVE INTO SRN IA. THIS WILL BRING BACK THE CHANCE FOR THUNDERSTORMS IN THAT REGION. A STRONG PV ANOMALY OVER SRN NEVADA WILL APPROACH IA LATE THURSDAY AND THURSDAY NIGHT. PREFER THE FARTHER NORTH NAM/ECMWF SOLUTION OVER THE LESS ORGANIZED AND FARTHER SOUTH GFS. THIS WOULD PLACE THE FOCUS FOR ADDITIONAL THUNDERSTORMS OVER NORTHWEST AND NORTH CENTRAL IOWA. THIS POPS CONTINUE INTO FRIDAY MAINLY OVER THE NORTH. EXPECT AT THIS POINT THAT POPS MAY BE OVERDONE FOR FRIDAY. HAVE BEGUN TO TRIM BACK OVER THE CENTRAL AND SOUTH BUT IT MAY VERY WELL BE MOSTLY DRY MOST LOCATIONS. THE SAME CAN BE SAID FOR FRIDAY NIGHT WHERE POPS HAVE BEEN DROPPED FOR ALL BUT THE FAR NORTHEAST. IOWA WILL BE IN THE WARM SECTOR ON SATURDAY AND WHILE LOW POPS REMAIN...THE CONVECTIVE INHIBITION SHOULD HOLD STRONG MUCH OF THE DAY. THE PRECIPITATION CHANCES THROUGH THE REMAINDER OF THE PERIOD ARE MORE COMPLEX. THE INITIAL WAVE TO MOVE INTO THE INTER MOUNTAIN WEST WILL BE FOLLOWED BY ANOTHER INTENSE PIECE OF ENERGY SATURDAY NIGHT INTO SUNDAY. LONG RANGE GUIDANCE IS BEGINNING TO FAVOR THE TWO TO MERGE AND FORM A CLOSED LOW TO THE WEST/NORTHWEST OF THE AREA. THE FIRST WAVE WILL NUDGE THE UPPER LEVEL RIDGE ENOUGH EAST SATURDAY NIGHT TO BRING A RETURN FOR PRECIPITATION CHANCES...MAINLY OVER THE NORTH HOWEVER THE EVOLUTION TO A CLOSE LOW WILL SLOW THE BOUNDARY ARRIVAL TO LATER SUNDAY INTO MONDAY. INCREASING SOUTHWEST FLOW OVER THE STATE WILL KEEP THE PERIOD ACTIVE AND EVENTUALLY SHOULD BRING A SEVERE WEATHER THREAT TO THE STATE. TEMPERATURES THROUGH THE PERIOD WILL GENERALLY BE ABOVE SEASONAL VALUES. COOLER ACROSS THE SOUTH ON THURSDAY DUE TO ENHANCED CLOUD COVER THEN WARMER AGAIN FRIDAY INTO SATURDAY. && .AVIATION...15/12Z ISSUED AT 612 AM CDT WED MAY 15 2013 VFR CONDITIONS WILL PREVAIL THROUGHOUT THE ENTIRE TAF PERIOD AS SURFACE HIGH PRESSURE BUILDS INTO THE STATE TODAY. WINDS WILL GRADUALLY SHIFT TO EAST TODAY AND REMAIN EAST OR VARIABLE THROUGH THURSDAY MORNING. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...PODRAZIK LONG TERM...DONAVON AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
400 AM CDT WED MAY 15 2013 .SHORT TERM.../TODAY /... ISSUED AT 359 AM CDT WED MAY 15 2013 SURFACE HIGH PRESSURE WILL MOVE INTO THE STATE TODAY AND WILL PROVIDE A MUCH QUIETER DAY ACROSS THE FORECAST AREA. THERE IS A SMALL POTENTIAL FOR SOME VERY HIGH BASED SHOWERS AND A STRAY THUNDERSTORM ACROSS NORTHERN IOWA THIS MORNING...DUE TO SOME WEAK THETA-E ADVECTION AND FORCING BETWEEN 700-500MB. HRRR HAS THE ISOLATED SHOWERS THROUGH 18Z...BUT 00Z NMM WRF DIMINISHING THE SHOWER ACTIVITY BEFORE ENTERING THE STATE. LEANED TOWARD THE HRRR AS IT SEEMED TO HAVE A DECENT GRASP ON CURRENT RADAR TRENDS. WEAK BOUNDARY ACROSS SOUTHERN IOWA LOOKS TO BE A FOCAL POINT FOR SOME ISOLATED THUNDERSTORMS THIS AFTERNOON. AGAIN...VERY HIGH BASED AS VERY MINIMAL MOISTURE BELOW 700MB. MAX TEMPS TODAY A LITTLE TRICK AS THINK GUIDANCE IS TOO LOW AGAIN AND FELT CONFIDENT ENOUGH TO TWEAK TEMPS UP TODAY...ESPECIALLY ACROSS THE SOUTH WHERE THE COOLER AIR DOES NOT REACH THIS AREA UNTIL THE AFTERNOON. WENT ABOVE GUIDANCE ACROSS THE CENTRAL TO SOUTHERN PORTIONS OF THE FORECAST AREA...WHICH WAS FAIRLY CLOSE TO THE MAV MOS GUIDANCE. IN NORTHERN IOWA WENT CLOSER THE THE NAM/MET MOS GUIDANCE FOR MAX TEMPS. .LONG TERM.../TONIGHT THROUGH TUESDAY/... ISSUED AT 359 AM CDT WED MAY 15 2013 RELATIVELY ACTIVE PERIOD THROUGH THE EXTENDED. HIGH PRESSURE WILL GRADUALLY DEPART TONIGHT INTO THURSDAY AND AS IT DOES...A STALLED FRONTAL BOUNDARY OVER NORTHERN MISSOURI WILL BEGIN TO LIFT BACK NORTH INTO IOWA. AS THIS OCCURS...A PLUME OF MOISTURE LIFTING THROUGH OKLAHOMA AND KANSAS WILL ARRIVE INTO SRN IA. THIS WILL BRING BACK THE CHANCE FOR THUNDERSTORMS IN THAT REGION. A STRONG PV ANOMALY OVER SRN NEVADA WILL APPROACH IA LATE THURSDAY AND THURSDAY NIGHT. PREFER THE FARTHER NORTH NAM/ECMWF SOLUTION OVER THE LESS ORGANIZED AND FARTHER SOUTH GFS. THIS WOULD PLACE THE FOCUS FOR ADDITIONAL THUNDERSTORMS OVER NORTHWEST AND NORTH CENTRAL IOWA. THIS POPS CONTINUE INTO FRIDAY MAINLY OVER THE NORTH. EXPECT AT THIS POINT THAT POPS MAY BE OVERDONE FOR FRIDAY. HAVE BEGUN TO TRIM BACK OVER THE CENTRAL AND SOUTH BUT IT MAY VERY WELL BE MOSTLY DRY MOST LOCATIONS. THE SAME CAN BE SAID FOR FRIDAY NIGHT WHERE POPS HAVE BEEN DROPPED FOR ALL BUT THE FAR NORTHEAST. IOWA WILL BE IN THE WARM SECTOR ON SATURDAY AND WHILE LOW POPS REMAIN...THE CONVECTIVE INHIBITION SHOULD HOLD STRONG MUCH OF THE DAY. THE PRECIPITATION CHANCES THROUGH THE REMAINDER OF THE PERIOD ARE MORE COMPLEX. THE INITIAL WAVE TO MOVE INTO THE INTER MOUNTAIN WEST WILL BE FOLLOWED BY ANOTHER INTENSE PIECE OF ENERGY SATURDAY NIGHT INTO SUNDAY. LONG RANGE GUIDANCE IS BEGINNING TO FAVOR THE TWO TO MERGE AND FORM A CLOSED LOW TO THE WEST/NORTHWEST OF THE AREA. THE FIRST WAVE WILL NUDGE THE UPPER LEVEL RIDGE ENOUGH EAST SATURDAY NIGHT TO BRING A RETURN FOR PRECIPITATION CHANCES...MAINLY OVER THE NORTH HOWEVER THE EVOLUTION TO A CLOSE LOW WILL SLOW THE BOUNDARY ARRIVAL TO LATER SUNDAY INTO MONDAY. INCREASING SOUTHWEST FLOW OVER THE STATE WILL KEEP THE PERIOD ACTIVE AND EVENTUALLY SHOULD BRING A SEVERE WEATHER THREAT TO THE STATE. TEMPERATURES THROUGH THE PERIOD WILL GENERALLY BE ABOVE SEASONAL VALUES. COOLER ACROSS THE SOUTH ON THURSDAY DUE TO ENHANCED CLOUD COVER THEN WARMER AGAIN FRIDAY INTO SATURDAY. && .AVIATION...15/06Z ISSUED AT 1129 PM CDT TUE MAY 14 2013 A COLD FRONT HAS SLOWED BUT IS STILL PUSHING SOUTHEAST ACROSS THE AREA...WITH SW WINDS AT DSM/OTM AND NW WINDS AT THE OTHER TERMINALS. WINDS WILL SWITCH TO NW EVERYWHERE BEFORE SUNRISE...THEN TURN THROUGH N TO NE OR E BY WED EVENING...BUT WITH SPEEDS LESS THAN 12 KT THROUGHOUT. ONLY HIGH CLOUDS ARE EXPECTED AND NO PRECIP FORECAST OTHER THAN POSSIBLY A FEW SPRINKLES BUT EVEN THOSE ARE UNLIKELY AT ANY GIVEN TERMINAL. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...PODRAZIK LONG TERM...DONAVON AVIATION...LEE
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1219 AM CDT WED MAY 15 2013 ...UPDATED FOR THE AVIATION DISCUSSION... .SYNOPSIS... ISSUED AT 931 AM CDT TUE MAY 14 2013 THE 14.12Z 250 HPA RAOB MAP SHOWED TWO JETS ACROSS NORTH AMERICA. THE POLAR JET WAS LOCATED ACROSS THE NORTHERN PORTIONS OF UNITED STATES AND INTO CANADA. THE STRONGEST WINDS WERE LOCATED FROM NOVA SCOTIA AND INTO THE CANADIAN MARITIMES WITH MAGNITUDES AROUND 180 KT. NEXT, THE SUBTROPICAL JET WAS LOCATED FARTHER SOUTH WITH HIGHEST MAGNITUDES AROUND 90 KT ACROSS FLORIDA. CLOSER TO KANSAS, FLOW WAS QUITE WEAK AT 15 KT. AT 500 HPA, A TROF WAS MOVING ONSHORE ACROSS CENTRAL CALIFORNIA. DAMPENING SHORTWAVE RIDGING WAS DOWNSTREAM OF THIS FEATURE ACROSS THE 4 CORNERS REGION. A WEAK LOW WAS LOCATED ACROSS PORTIONS OF MEXICO. A SHORTWAVE TROF WAS MOVING ACROSS THE CENTRAL CANADIAN PRAIRIES. AN ELONGATED TROF WAS LOCATED ACROSS THE NE U.S. AND SE CANADA. AT 700 HPA, TEMPERATURES ACROSS SW KANSAS WERE FAIRLY WARM (10 DEG C). AT 850 HPA, 25 DEG C AT KDDC WAS SLIGHTLY UNDER THE +2 STANDARD DEVIATION STATISTICAL MARK. AT THE SFC, A COLD FRONT WAS LOCATED ACROSS THE NORTHERN PLAINS AND A SURFACE LEE TROF WAS LOCATED ACROSS FAR WESTERN KANSAS. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 252 PM CDT TUE MAY 14 2013 TONIGHT: EARLY AFTERNOON VISIBLE SATELLITE IMAGERY SHOWS A FIELD OF CUMULUS HUMILIS CLOUDS ACROSS NORTHWEST KANSAS. THESE CLOUDS ARE IN ASSOCIATION WITH A LEE SURFACE TROF ACROSS NORTHWEST KANSAS AND WEAK INSTABILITY. RAP AND HRRR KEEPS THIS ACTIVITY NORTHWEST OF THE FORECAST AREA OF RESPONSIBILITY THROUGH TONIGHT. I HAVE 14 PERCENT PRECIPITATION PROBABILITIES IN THE GRIDS THROUGH EARLY EVENING ACROSS WEST CENTRAL KANSAS. OTHERWISE, TONIGHT WILL BE CLEAR AND PRECIPITATION FREE. LEE TROUGHING WILL CONTINUE THROUGH THE OVERNIGHT PERIOD. SOUTHERLY WINDS IN ASSOCIATION WITH THIS FEATURE WILL CONTINUE OVERNIGHT AS WELL. THESE WINDS WILL KEEP TEMPERATURES MILD WITH LOWS IN THE UPPER 50S AND LOWER 60S DEG F. TOMORROW: ON WEDNESDAY, A LEE INDUCED LOW/TROF ACROSS SOUTHEASTERN COLORADO WILL DEEPEN THROUGH THE AFTERNOON. THIS WILL CAUSE A WARM FRONT TO LIFT NORTHWARD ACROSS PORTIONS OF WESTERN KANSAS. HIGHS TOMORROW IN THE WARM SECTOR WILL BE WARM TO HOT AGAIN WITH HIGHS IN THE 86-91 DEG F RANGE. RAMPED UP POPS IN THE AFTERNOON ACROSS THE EASTERN PORTIONS OF THE FORECAST AREA OF RESPONSIBILITY. THERE IS SOME UNCERTAINTY IN WHERE CONVECTION WILL DEVELOP ALONG THE FRONT AS MODELS DIFFER WITH THE FRONT POSITION. 12Z NAM DEVELOPS THUNDERSTORMS FROM LIBERAL TO HAYS, WHILE 12Z GFS KEEPS PRECIPITATION MAINLY EAST OF HIGHWAY 183. THE WRF-NMM ECHOES THE NAM SOLUTION, WHERE THE WRF-ARW KEEPS THE REGION DRY. DUE TO THE UNCERTAINTY, WILL LIMIT PRECIPITATION PROBABILITIES IN THE SLIGHT CHANCE CATEGORY. IF THE NAM SOLUTION IS CORRECT WITH MOISTURE, MLCAPE LOOKS TO BE AROUND 1500-3000 J/KG, MAINLY ACROSS SC KANSAS. 0-6 KM BULK SHEAR IS ON THE WEAKER SIDE AT 30-35 KT. UPPER LEVEL WIND SHEAR IS VERY WEAK AT 15-30 KT. LCL`S WILL BE FAIRLY HIGH AS WELL. PUTTING THIS ALL TOGETHER, THE OVERALL THREAT FOR HIGH END SEVERE WEATHER IS VERY LOW. THE MAIN THREAT TOMORROW IS MARGINAL HAIL SIZE PERHAPS UP TO QUARTERS AND 50-60 MPH OUTFLOW FROM THUNDERSTORMS. LASTLY, LESS FIRE WEATHER CONCERNS ARE EXPECTED TOMORROW AFTERNOON AS SLIGHTLY HIGHER DEWPOINTS AND RESULTANT HIGHER RELATIVE HUMIDITIES ARE EXPECTED. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 354 PM CDT TUE MAY 14 2013 PRECIPITATION CHANCES, SEVERITY, AND COVERAGE WILL BE CHALLENGES IN THE FORECAST LATE WEEK INTO THE WEEKEND...ALONG WITH AFTERNOON TEMPERATURES WITH DRYLINE POSITION UNCERTAINTY. WEDNESDAY NIGHT THROUGH THURSDAY NIGHT: A LOW AMPLITUDE SHORTWAVE TROUGH (CURRENTLY SEEN ON WATER VAPOR SPINNING ACROSS CENTRAL CALIFORNIA) WILL BE MOVING TOWARD THE CENTRAL HIGH PLAINS DURING THIS TIME FRAME. A WEAK FRONT MOVING INTO EAST-CENTRAL COLORADO AND WEST-CENTRAL KANSAS WILL BE THE FOCUS FOR THUNDERSTORMS LATE AFTERNOON WEDNESDAY...BUT THIS FRONT WILL DISSOLVE BY WEDNESDAY NIGHT. A SMALL...LOOSELY ORGANIZED AREA OF CONVECTION AHEAD OF THE APPROACHING WAVE MAY HOLD TOGETHER AS IT APPROACHES FAR WEST-CENTRAL KANSAS...BUT CONFIDENCE IN THIS IS VERY LOW AND ONLY SLIGHT CHANCE POPS ARE WARRANTED AT THIS TIME. ON THURSDAY...THERE IS A LOT OF DISAGREEMENT ON THE 850MB THERMODYNAMICS/MOISTURE BETWEEN THE NCEP MODELS AND THE ECMWF MODEL. THE GFS AND NAM SHOW COPIOUS AMOUNTS OF MOISTURE AND NEAR-SATURATED RH AT 850MB THROUGH 18Z THURSDAY WHICH IS AFFECTING THE BOUNDARY LAYER TEMPERATURES TO THE POINT THAT THE NCEP MODELS KEEP TEMPERATURES IN THE 70S FOR MUCH OF THE DAY. THE NCEP MODELS TEND TO BE A BIT TOO AGGRESSIVE IN HOLDING ONTO STRATUS TOO LONG SO THE OFFICIAL FORECAST FOR HIGHS THURSDAY WILL REFLECT MORE CLOSELY THE ECMWF MODEL. A DRYLINE WILL NO DOUBT BE A PREVAILING FEATURE, HOWEVER, WHICH SHOULD FOCUS A FEW ISOLATED STORMS BY LATE AFTERNOON/EARLY EVENING...ESPECIALLY SINCE THE AFOREMENTIONED LOW AMPLITUDE SHORTWAVE TROUGH WILL BE PASSING JUST TO THE NORTH AIDING IN SOME SLIGHT MID LEVEL COOLING AND OVERALL SLIGHT ENHANCEMENT OF DEEP TROPOSPHERIC UPWARD VERTICAL MOTION. MID LEVEL FLOW AT THE BASE OF THIS TROUGH AXIS OF 25 TO 35 KNOTS (500MB) ACROSS WESTERN KANSAS WILL PROVIDE THE NECESSARY SHEAR ALONG WITH SOUTH-SOUTHEAST BOUNDARY LAYER FLOW FOR SUPERCELL STORMS (ALONG WITH THE UPPER 50S TO NEAR 60 DEWPOINTS AT THE SURFACE). ANY THUNDERSTORMS LATE THURSDAY/THURSDAY EVENING SHOULD DISSOLVE AFTER SUNSET AS INSOLATION GOES AWAY AND THE SHORTWAVE TROUGH EXITS THE CENTRAL PLAINS. FRIDAY AND SATURDAY: A MUCH MORE IMPRESSIVE PACIFIC JET WILL ENTER THE SOUTHWEST/GREAT BASIN REGION DURING THIS TIME FRAME...ENTERING THE ROCKIES AND WESTERN PLAINS SATURDAY. THE DRYLINE WILL BE THE FOCUS FOR THUNDERSTORMS BOTH OF THESE DAYS...BUT SATURDAY WILL BE THE BETTER DAY OF THE TWO FOR MORE ORGANIZED SUPERCELL STORMS GIVEN THE GREATER LOW LEVEL CONVERGENCE EXPECTED ALONG THE DRYLINE NEAR AND JUST SOUTH OF THE SURFACE LOW. WILL HAVE CHANCE POPS NORTH OF A DIGHTON TO LACROSSE LINE WHERE THE FORECAST SURFACE LOW WILL BE PER THE ECMWF MODEL. SOUTH AND SOUTHWEST OF THE SURFACE LOW...HOT TEMPERATURES WILL BE FOUND OVER A LARGER AREA THAN PREVIOUS DAYS WITH SOME UPPER 90S EVEN POSSIBLE. SUNDAY AND BEYOND: THE INITIAL JET STREAK WILL LIFT NORTH INTO THE NORTHERN PLAINS LEADING TO THE FORMATION OF AN UPPER LOW...HOWEVER AN ENERGETIC JET WILL STILL REMAIN ACROSS THE GREAT BASIN INTO THE CENTRAL ROCKIES WHICH COULD LEAD TO DEVELOPMENT OF A SECONDARY LOW LATE SUNDAY INTO MONDAY. SOME SLIGHT CHANCE POPS WERE INCLUDED THROUGH THE ALLBLEND GUIDANCE ON SUNDAY AND MONDAY GIVEN THE PROSPECTS OF SOME POTENTIAL POST-FRONTAL CONVECTION ROLLING EAST OFF THE EASTERN COLORADO TERRAIN. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1209 AM CDT WED MAY 15 2013 THIS PERIOD WILL HAVE VFR CONDITIONS THROUGH THE NEXT 24 HOURS. A TROUGH OF LOW PRESSURE ASSURE SOUTHWEST WINDS OF 10 TO 15 KNOTS THIS MORNING, BUT THEY WILL CHANGE TO SOUTHEAST AFTER SUNRISE, AND THEN TO EASTERLY BY THIS AFTERNOON. A LOW PRESSURE AREA WILL MOVE THROUGH NORTHERN KANSAS, AND HELP PULL DOWN A COLD FRONT THIS AFTERNOON. CIGS MAY RESULT IN THE BKN080-120 RANGE. && .PRELIMINARY POINT TEMPS/POPS... DDC 60 86 64 91 / 20 10 20 20 GCK 59 88 62 95 / 10 20 20 20 EHA 58 92 60 97 / 10 20 20 20 LBL 60 92 61 97 / 10 10 20 20 HYS 60 83 64 85 / 20 10 20 10 P28 63 84 65 85 / 20 10 10 10 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...SUGDEN SHORT TERM...SUGDEN LONG TERM...UMSCHEID AVIATION...BURKE
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
351 AM EDT WED MAY 15 2013 .SYNOPSIS... A FRONTAL BOUNDARY WILL APPROACH FROM PENNSYLVANIA LATE TODAY AND STALL OUT OVER THE SOUTHERN MID-ATLANTIC THROUGH THE END OF THE WEEK AND INTO THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... THE CONVEYOR BELT OF ISOLATED SHOWERS CONTINUES OVER THE NERN QUADRANT OF THE CWA...A STEADY STREAM OF SPRINKLES COMING OUT OF MID CLOUD DECKS. BUT THE MAIN STORY OF THE NEAR TERM IS THE TEMPERATURES. WE`RE NOW A SOLID 10-15 DEG ABOVE CONDITIONS AT THIS TIME 24 HRS AGO. THIS DIFFERENCE WILL CARRY OVER AND EVEN MORE SO INTO THE AFTN HRS TODAY...AS WE PEAK WELL INTO THE 80S ACROSS MUCH OF THE REGION. A RELATIVELY SMALL BUT VERY STRONG UPPER RIDGE CENTERED OVER THE NRN PLAINS DEVELOPED A LOCALIZED AREA OF TEMPS IN THE UPPER 90S/L100S YESTERDAY AFTN. AT THE SAME TIME NEAR TRIPLE-DIGIT HEAT WAS OCCURRING...ONLY A FEW HUNDRED MILES TO THE EAST - OVER THE GREAT LAKES - TEMPS WERE ONLY THE 50S. IN BETWEEN THESE AREAS RESIDES A HIGHWAY OF FAST UPPER FLOW CREATED BY THESE STRONG OPPOSING FORCES. A PIECE OF THIS ENERGY FROM THE WEST WILL BE FORCED TOWARD THE AREA TODAY. A COMPLEX SFC SCENARIO W/ ALL THESE POTENT BUT SMALL SCALE FEATURES MOVING ABOUT THE NRN HALF OF THE COUNTRY TODAY. A WARM FRONT HAS BEEN FORMING ALONG THE I-70 CORRIDOR OF THE UPPER MIDWEST... STRETCHING HUNDREDS OF MILES AND WILL EVENTUALLY BECOME A WX-MAKER FOR THE AREA BEGINNING LATE TONIGHT AND INTO EARLY FRI. FOR TODAY...A COLD FRONT DRIFTING DOWN FROM THE SYSTEM THAT BROUGHT COOL TEMPS TO THE GREAT LAKES YESTERDAY WILL STAY WELL TO THE NORTH BUT JOIN UP W/ THE WARM FRONT AND BECOME A PSEUDO-STATIONARY BOUNDARY NEAR THE MASON-DIXON LINE OVERNIGHT. LOCAL GUIDANCE LIKE THE HRRR AND GFS-BASED WRF MODELS TAKING THE ACTIVITY CURRENTLY OVER THE LAKE ERIE REGION...SPILLING IT OVER INTO THE ERN HALF OF THE CWA LATER THIS MRNG AND EARLY AFTN. PLACED AN ISOLATED/SCATTERED POP FOR THESE AREAS...DRYING OUT AND CLEARING OUT DURING THE AFTN. A QUICK RETURN TO THE CLOUDS AND PRECIP ALONG THE MASON-DIXON LINE LATE THIS AFTN THOUGH...AS HI-RES MODELS CONTINUING TO DEPICT A DEVELOPMENT OF CONVECTION JUST TO OUR NORTH - POTENTIALLY DRIFTING ESE INTO THE NRN TIER COUNTIES TOWARD LATE EVE...DISSIPATING OVERNIGHT BEFORE HEADING TOO FAR SOUTH. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... FRONTAL BOUNDARY IS FORECAST TO SINK SOUTHWARD ACROSS THE SOUTHERN MID-ATLANTIC THROUGH THE END OF THE WEEK...POSSIBLY SNAKING BACK UP THE APPALACHIANS ON FRIDAY. WITH FRONTAL BOUNDARY OVER THE CWA ON THURSDAY...WILL CONTINUE WITH CHANCE POPS MAINLY IN THE AFTERNOON/EVENING WITH MAXIMA IN THE LOWER TO MID 80S. WITH FRONT SAGGING A LITTLE FURTHER SOUTH INTO FRIDAY...WILL FOCUS POPS ACROSS THE SOUTHERN HALF ON THE CWA WITH MAXIMA POSSIBLY A COUPLE OF DEGREES LOWER. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... FRONTAL BOUNDARY IS FORECAST TO REMAIN SOUTH OF THE AREA OVER THE WEEKEND...THEN LIFTS BACK NORTH AS A WARM FRONT EARLY NEXT WEEK IN ADVANCE OF THE NEXT SHORTWAVE. FEW ADJUSTMENTS WERE MADE TO THE FORECAST WHICH INCLUDE CHANCE POPS THROUGH MUCH OF THE PERIOD. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... LITTLE HAS CHANGED IN TERMS OF THE SOLID 7-8KFT DECK OVER THE METRO DC/BALT AREAS AND EVEN A FEW INTERMITTENT SPRINKLES ALONG THE WAY. THIS WILL CONTINUE THRU DAWN AND POSSIBLY INTO THE LATE MRNG HRS ACROSS A PORTION OF NERN MD. THIS ACTIVITY IS EXPECTED TO DISSIPATE AND RECEDE TO THE NORTH DURING THE AFTN HRS...AS SLY WINDS PICK UP INTO THE G20-25KT RANGE. MID DECKS WILL RETURN FROM THE NORTH LATE THIS EVE...BUT MAINLY TO THE NORTH OF THE I-66 CORRIDOR W/ SOLID VFR CONDITIONS THRU THE TAF PERIOD. FRONTAL BOUNDARY IS FORECAST TO STALL OUT TO THE SOUTH OF THE AREA DURING THE LATE WEEK-WEEKEND PERIOD. WITH BOUNDARY FAIRLY CLOSE...CONVECTION IS POSSIBLE MAINLY IN THE AFTERNOON/EVENING EACH DAY. && .MARINE... SLY CHANNELING CONTINUES OVERNIGHT AND WILL CONTINUE TO SLOWLY BUILD W/ OBS HOVERING IN THE LOW-END SCA RANGE. THESE CONDITIONS WILL SPREAD FURTHER NORTH INTO THE MRNG HRS...AND OVER THE TP RVR BY LATE MRNG. THE AFTN HRS WILL SEE THE HIGHER SYNOPTIC GUSTS THIS AFTN...W/ MOST AREAS IN SOLID SCA RANGE AND A FEW GUSTS IN THE U20KT RANGE BEFORE SUNSET. A FEW ISOLATED SHOWERS WILL ALSO CONTINUE THIS MRNG...AND AGAIN ANOTHER ROUND OVER THE NRN BAY LATE TONIGHT. FRONTAL BOUNDARY SLIPS SOUTH OF THE WATERS LATE WEEK AND REMAINS SOUTH THROUGH THE WEEKEND. GRADIENT IS EXPECTED TO REMAIN FAIRLY WEAK THROUGH THE PERIOD. AS WINDS BECOME SOUTHEAST OVER THE WEEKEND...WINDS MAY CREEP UP CLOSE TO SCA LEVELS OVER PORTIONS OF THE WATERS. && .TIDES/COASTAL FLOODING... THE SLY CHANNELING OF WINDS UP THE MAIN STEM OF THE BAY HAS INCREASED POSITIVE TIDAL ANOMALIES TOWARD THE 1 FT ABOVE MARK BUT STILL CLOSER TO 3/4FT ATTM. WATER LEVEL MODEL GUIDANCE KEEPING ANNAPOLIS UNDER MINOR THRESHOLDS FOR THE UPCOMING H.T. CYCLE WHICH WILL BE THE MOST SENSITIVE AND BEST CHANCE FOR MINOR TIDAL FLOODING IN THE NEAR TERM. WINDS WILL CONTINUE TO GUST OUT OF THE SOUTH FOR MUCH OF THE DAY...BEFORE A COLD FRONT ARRIVES LATE TONIGHT AND BEGINS TO TAPER OFF THESE WINDS AND CHANGE DIRECTIONS TO MORE WLY AND CAUSE LEVELS TO DROP AGAIN. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ531>534- 537-539>541-543. SMALL CRAFT ADVISORY FROM NOON TODAY TO 8 PM EDT THIS EVENING FOR ANZ530-535-536-538-542. && $$ SYNOPSIS...GMS/BPP NEAR TERM...GMS SHORT TERM...BPP LONG TERM...BPP AVIATION...GMS/BPP MARINE...GMS/BPP TIDES/COASTAL FLOODING...GMS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
728 PM EDT THU MAY 16 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 421 PM EDT THU MAY 16 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW TROFFING ALONG THE W COAST OF THE CONUS...BROAD RIDGING OVER THE CNTRL CONUS...AND A TROF EXTENDING S INTO NEW ENGLAND. AHEAD OF THE RIDGE...IT`S BEEN A GENERALLY SUNNY DAY ACROSS THE FCST AREA. WITH THE DRY AIR NOTED ON THE 12Z KGRB SOUNDING...DWPTS HAVE FALLEN INTO THE 20S OVER PORTIONS OF THE INTERIOR W HALF OF UPPER MI...RESULTING IN RH DOWN AROUND 20PCT. SFC HIGH PRES ASSOCIATED WITH APPROACHING MID LEVEL RIDGE IS SETTLING S OVER THE UPPER GREAT LAKES AND WILL LEAD TO A QUIET NIGHT TONIGHT. TO THE W...A COUPLE OF SHORTWAVES EMERGING OVER THE WRN HIGH PLAINS ARE GENERATING SHRA/TSRA FROM ND TO NEBRASKA. THE SRN WAVE OVER WRN NEBRASKA IS THE STRONGER ONE. HEADING INTO LATER FRI...FCST WILL REVOLVE AROUND WHAT AFFECTS THESE WAVES WILL HAVE FOR UPPER MI. AS ALLUDED TO ABOVE...SFC HIGH PRES WILL LEAD TO A TRANQUIL NIGHT ACROSS THE FCST AREA. MAINLY CLEAR SKIES WITH PRECIPITABLE WATER AROUND 50PCT OF NORMAL WILL LEAD TO A QUICK TEMP DROP AFTER SUNSET. COLUMN MOISTURE BEGINS TO INCREASE OVER THE W OVERNIGHT...AND SOME OF THAT WILL MANIFEST ITSELF AS HIGH AND MID CLOUDS SPREADING E FROM THE SHRA AREA CURRENTLY OVER THE DAKOTAS. IN THE END...THIS SHOULD LEAD TO LOWEST MINS OVER THE E...THOUGH SOME OF THE TRADITIONAL COLD SPOTS OVER THE W MAY BE EQUALLY AS LOW GIVEN THE GOOD RADIATIONAL COOLING CONDITIONS EARLY IN THE NIGHT. GENERALLY FAVORED THE LOWER END OF GUIDANCE ACROSS THE BOARD IN THE INTERIOR. A FEW OF THE TYPICAL COLD SPOTS MAY SLIP JUST BLO 30F. WHETHER ANY PCPN MAKES INTO THE FCST AREA FRI IS THE BIG QUESTION. THE NAM IS VERY AGRESSIVE WITH PCPN...BRINGING OVER AN INCH OF RAIN TO KIWD BY 00Z SAT WITH PCPN SPREADING AS FAR E AS SENEY. THE GFS FOLLOWS CLOSE BEHIND THE NAM...THOUGH ITS PCPN FIELD IS DISPLACED A LITTLE FARTHER S. THE GEM HAS NO PCPN THRU 00Z SAT...THE UKMET ONLY BRINGS A FEW HUNDREDTHS TO SCNTRL UPPER MI...AND THE 12Z ECMWF IS SIMILAR WITH A FEW HUNDREDTHS ALONG THE WI BORDER WHICH IS FARTHER S AND W THAN ITS 00Z RUN. SUSPECT THE STRONGER MORE WELL-DEFINED SRN WAVE OVER THE WRN PLAINS WILL BE THE BIGGER PLAYER...RESULTING IN PCPN WITH THE NRN WAVE OVER ND GRADUALLY DRYING UP AS IT WILL HAVE LIMITED/NO MOISTURE INFLOW AND IT WILL BE ENCOUNTERING DRIER AIR TO THE E. EVEN PCPN WITH THE SRN WAVE WILL PROBABLY TEND TO DIMINISH OR AT LEAST BE SLOWER TO ARRIVE DUE TO THE DRIER AIR OVER GREAT LAKES...ESPECIALLY SINCE LOW-LEVEL TRAJECTORIES HAVE A GOOD EASTERLY COMPONENT FRI THAT WILL HELP TO MAINTAIN DRY AIR OVER THE AREA. SO PLAN WILL BE TO FAVOR THE DRIER NON NCEP MODELS FOR FRI. WHILE RELUCTANT TO ADD PCPN CHC...WILL INCLUDE A SCHC MENTION ALONG THE WI BORDER SINCE THE THERE WAS ONLY ONE MODEL (GEM) THAT HAD A COMPLETELY DRY FCST. FOLLOWING THE DRIER SCENARIO...ALSO UTILIZED LOWER DWPTS FOR FRI BY COMBINING SOME OF THE BIAS CORRECTED GUIDANCE (GEM IN PARTICULAR) WITH DWPTS CALCULATED BASED ON MIXING HEIGHT. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 421 PM EDT THU MAY 16 2013 CONFIDENCE IS STILL RATHER LOW ON QPF POTENTIAL FRIDAY NIGHT INTO SATURDAY ASSOCIATED WITH THE DEVELOPING BAROCLINIC ZONE. AS THE 850MB LOW OVER THE CENTRAL AND NORTHERN ROCKIES MOVES EAST...STRONG WARM ADVECTION AND ISENTROPIC LIFT WILL SPREAD ACROSS THE UPPER MIDWEST. THE NAM IS VERY AGGRESSIVE IN DEVELOPING SIGNIFICANT ELEVATED CONVECTION CLOSE TO THE MI/WI BORDER LATE FRI AFTN INTO FRIDAY NIGHT...WITH OVER 2 INCHES OF QPF FORECAST AT IMT AND IWD BY SAT AFTN. THE 12Z GFS HAS SHIFTED THE BAROCLINIC AXIS NORTHWARD...BUT IT IS NOT AS STRONG AS THE NAM. THE 00Z ECMWF IS OVERALL THE WEAKEST WITH THE FRONTAL BOUNDARY BUT NONETHELESS IS SIMILAR IN POSITION BUT A LITTLE SLOWER (SIMILAR TO WHAT THE 18Z NAM SHOWS). THE GEM IS MUCH FURTHER SOUTH. WITH ALL THAT SAID...THE CONSENSUS OF DETERMINISTIC AND ENSEMBLE NWP SUGGEST THAT POPS WILL NEED TO BE RAISED ACROSS THE ENTIRE AREA (EXCEPT EAST 1/3) FRIDAY NIGHT INTO SATURDAY. WITH THE STRONGLY CONFLUENT FLOW AND DRY AIR IN PLACE...DO NOT EXPECT THE HEAVY PCPN PER THE NAM FORECAST...HOWEVER SOME SHOWER ACTIVITY FRIDAY NIGHT INTO SATURDAY IS EXPECTED ESPECIALLY CLOSER TO THE WI BORDER WHERE THE BETTER MOISTURE AND BETTER LIFT ASSOCIATED WITH THE FRONTAL ZONE IS LOCATED. BY SATURDAY AFTERNOON...THE BAROCLINIC ZONE SHIFTS NORTH OF THE AREA WITH THE BEST MOISTURE TRANSPORT CLOSER TO THE LOW TO THE WEST OF THE AREA. IN FACT...WILL LIKELY SEE SOME CLEARING LATE SAT AFTN AS THE WARM SECTOR MOVES OVER THE AREA AND DRIER AIR ADVECTS INTO THE AREA. WILL MAINTAIN LOW CHANCE POPS WEST SAT AFTN/NIGHT...BUT GENERALLY DRY ELSEWHERE. SUNDAY SHOULD END UP BEING GENERALLY DRY WITH THE BEST MOISTURE AND LOW LVL JET TO THE WEST OF THE AREA. NAM AND GFS ARE VERY AGGRESSIVE IN WARMING 850MB TEMPS TO +18C ACROSS THE SOUTH...BUT AM THINKING THE MORE CONSERVATIVE ECMWF WITH 850MB TEMPS AROUND +14 SEEMS MORE REASONABLE. REGARDLESS...SHOULD BE A NICE DAY WITH PERHAPS A CHANCE OF SHOWERS AND THUNDERSTORMS LATE IN THE DAY SUNDAY ACROSS THE WEST. RATHER UNSETTLED WEATHER WILL CONTINUE THROUGH THE EARLY PART OF NEXT WEEK WITH THE UPPER LOW OVER THE NORTHERN PLAINS BEING RATHER STUBBORN TO MOVE OUT. THIS WILL KEEP THE BAROCLINIC ZONE NEARBY THROUGH WEDNESDAY BEFORE AN UPPER TROUGH OVER HUDSON BAY DIVES SOUTH AND ALLOWS THE FRONT TO MOVE SOUTH OF THE AREA BY THURSDAY. WITH THAT SAID...MON-WED LOOKS QUITE WET AT TIMES WITH SOME HEAVY RAIN CERTAINLY POSSIBLE. ALTHOUGH 850MB TEMPS WILL BE AROUND +10C THROUGH WED...EASTERLY FLOW DUE TO THE LOW STAYING SOUTH OF THE AREA AS WELL AS PLENTIFUL CLOUDS WILL KEEP TEMPS COOL NEAR LAKE SUPERIOR. INLAND TEMPS WILL LIKELY STAY NEAR NORMAL...BUT TEMPS CLOSER TO LAKE SUPERIOR WILL BE IN THE UPPER 50S. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING) ISSUED AT 726 PM EDT THU MAY 16 2013 ALTHOUGH SOME HI CLDS WL BE ON THE INCREASE...EXPECT VFR CONDITIONS TO PREVAIL THRU THIS FCST PERIOD WITH DRY E WIND OUT OF HUDSON BAY HI PRES. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 421 PM EDT THU MAY 16 2013 LIGHT WINDS WILL BE THE RULE ACROSS LAKE SUPERIOR TONIGHT WITH HIGH PRES OVER THE UPPER LAKES. WHILE THE HIGH WILL BE SHIFTING E FRI...A MESO HIGH MAY LINGER OVER ERN LAKE SUPERIOR THRU THE DAY. THIS WILL KEEP WINDS LIGHT OVER THE E...BUT E TO NE WINDS WILL BEGIN TO INCREASE OVER THE W. HEADING THRU THE WEEKEND INTO EARLY NEXT WEEK...PRES GRADIENT OVER THE UPPER LAKES WILL SLOWLY TIGHTEN BTWN LOW PRES SLOWLY MOVING FROM THE WRN PLAINS TOWARD THE UPPER MISSISSIPPI VALLEY AND HIGH PRES BUILDING IN THE VCNTY OF WRN HUDSON BAY. THIS WILL LEAD TO EASTERLY WINDS GRADUALLY INCREASING INTO GENERALLY THE 15-25KT RANGE. COULD BE SOME PERIODS OF HIGHER WINDS AT TIMES EARLY NEXT WEEK...ESPECIALLY OVER WRN LAKE SUPERIOR WHERE FUNNELING/CHANNELING WILL ENHANCE THE WINDS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...MRD AVIATION...KC MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
440 PM EDT WED MAY 15 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 409 PM EDT WED MAY 15 2013 WV IMAGERY AND RUC ANALYSIS INDICATED WNW MID/UPPER LEVEL FLOW THROUGH THE NRN GREAT LAKES ON THE SRN FLANK OF A TROUGH OVER NRN ONTARIO TO THE SRN END OF JAMES BAY. A WEAK SHORTWAVE TROUGH OVER THE SE CORNER OF MANITOBA SUPPORTED AN AREA OF MID CLOUDS AND SOME SCT/ISOLD -SHRA INTO NW MN. AT THE SFC...A TIGHT PRES GRADIENT PERSISTED BTWN A 995 MB LOW BTWN JAMES BAY AND LAKE SUPERIOR AND A RIDGE FROM THE NRN PLAINS INTO SRN MN. WNW WINDS HAVE GUSTED AT OR ABOVE 30 MPH OVER MUCH OF UPPER MI AND TO NEAR 45 MPH WHERE TERRAIN HAS BOOSTED THE WINDS AT CMX. SUNSHINE WITH TEMPS INTO THE LOWER TO MID 70S AND DEEP MIXING TO AROUND 750 MB HAS LOWERED DEWPOINTS TO AROUND 30F WITH RH VALUES TO AROUND 20 PCT. THE COMBINATION OF THE DRY AIR WINDS HAS RESULTED IN CRITICAL FIRE WEATHER CONDITIONS. TONIGHT...AS THE PRES GRADIENT WEAKENS AND DAYTIME HEATING SUBSIDES...WINDS WILL DIMINISH QUICKLY THIS EVENING AND BECOME LIGHT OVERNIGHT. HIGHER RES SHORT RANGE MODELS SUGGEST THAT THE BEST CHANCES OF PCPN ASSOCIATED WITH THE MANITOBA SHORTWAVE OVER THE SW HALF OF UPPER MI. EVEN THERE...WITH DRY LOW LEVELS AND WEAK FORCING WITH THE SHRTWV MAINLY JUST SPRINKLES AT MOST WOULD BE EXPECTED. SO...ONLY A SMALL AREA OF SLIGHT CHANCE POPS WERE INCLUDED. THURSDAY...EXPECT COOLER CONDITIONS OVER THE NORTH HALF OF UPPER MI WITH NRLY WINDS BEHIND A COLD FRONT MOVING THROUGH THE AREA LATE TONIGHT. WITH 850 MB TEMPS RANGING FROM AROUND 4C NORTH TO TO 9C SOUTH...TEMPS SHOULD RANGE FROM THE LOWER 50S NEAR LAKE SUPERIOR TO THE LOWER 70S INLAND SOUTHWEST. SUNSHINE AND FAVORABLE MIXING WILL AGAIN DROP DEWPOINTS INTO THE LOWER 30S WITH RH VALUES TO AROUND 25 PERCENT SOUTH. HOWEVER...WITH WINDS ONLY TO AROUND 10 MPH...THE WILDFIRE RISK WILL BE LOWER THAN TODAY. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 440 PM EDT WED MAY 15 2013 TEMPS WILL HOLD STEADY IN THE 60S ON FRIDAY AND SATURDAY...WITH A WARM UP FOR SUNDAY AS SSE WINDS INCREASE AHEAD OF LOW PRESSURE NEARING FROM THE CENTRAL PLAINS. AT THIS POINT THE STRONGER WINDS LOOK TO BE ASSOCIATED WITH INCREASED DEW POINTS...LIMITING SIGNIFICANT FIRE CONCERNS. THERE IS A LOT OF UNCERTAINTY WITH THE MID TO LONGER RANGE OF THIS FORECAST...WITH THE TRACK AND TIMING OF THE SLOW MOVING LOW PRESSURE SYSTEM. WITH THAT SAID...THERE IS A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS IN THE FORECAST FROM SATURDAY ON /MAINLY WEST/. THUNDERSTORM CHANCES ARE NOT THAT IMPRESSIVE. IT LOOKS LIKE THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS ACROSS THE ENTIRE CWA WILL HOLD OFF UNTIL MONDAY...WITH THE SFC LOW IS SET UP OVER THE EASTERN DAKOTAS AND WESTERN MN. THE SYSTEM CONTINUES TO SLOW DOWN...AS IT WAS ORIGINALLY EXPECTED TO CROSS UPPER MI ON SUNDAY...AT LEAST OF A COUPLE OF DAYS AGO. NOW IT LOOKS TO HOLD OFF UNTIL TUESDAY AT THE EARLIEST /12Z ECMWF SOLUTION/. THE GFS IS EVEN SLOWER...AND HAS THE 500MB LOW OVER ND TUESDAY AFTERNOON RETROGRADING AND CONSOLIDATING WITH THE DEEP LOW PUSHING INTO THE PACIFIC NORTHWEST. WILL OPT FOR FOR A SOLUTION CLOSER TO THE ECMWF AT THIS POINT...WITH LOWER CONFIDENCE IN THE FORECAST BEYOND SUNDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 149 PM EDT WED MAY 15 2013 VFR CONDITIONS ARE EXPECTED TO PREVAIL AT ALL THREE TAF SITES THROUGH THE FORECAST PERIOD. EXPECT WNW WINDS TO GUST OVER 20 KTS AT ALL THE SITES TODAY...STRONGEST AT KCMX AND KSAW. ONLY SKY COVER WILL BE SCT-BKN MID CLOUDS...ESPECIALLY THIS AFTERNOON AND EVENING. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 409 PM EDT WED MAY 15 2013 EXPECT WINDS WITH GUSTS 25 KNOTS TO DIMINISH TONIGHT AS HIGH PRES BUILDS INTO THE REGION. HIGH PRESSURE WILL EXPAND ACROSS GREAT LAKES INTO THE WEEKEND WITH EAST-SOUTHEAST WINDS AT OR BLO 25 KTS. WINDS BECOME SOUTHERLY LATE THIS WEEKEND AHEAD OF LOW PRESSURE TROUGH PUSHING IN FROM NORTHERN PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... RED FLAG WARNING UNTIL 9 PM EDT /8 PM CDT/ THIS EVENING FOR MIZ002-004>006-009>014-084-085. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...KF AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
411 PM EDT WED MAY 15 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 409 PM EDT WED MAY 15 2013 WV IMAGERY AND RUC ANALYSIS INDICATED WNW MID/UPPER LEVEL FLOW THROUGH THE NRN GREAT LAKES ON THE SRN FLANK OF A TROUGH OVER NRN ONTARIO TO THE SRN END OF JAMES BAY. A WEAK SHORTWAVE TROUGH OVER THE SE CORNER OF MANITOBA SUPPORTED AN AREA OF MID CLOUDS AND SOME SCT/ISOLD -SHRA INTO NW MN. AT THE SFC...A TIGHT PRES GRADIENT PERSISTED BTWN A 995 MB LOW BTWN JAMES BAY AND LAKE SUPERIOR AND A RIDGE FROM THE NRN PLAINS INTO SRN MN. WNW WINDS HAVE GUSTED AT OR ABOVE 30 MPH OVER MUCH OF UPPER MI AND TO NEAR 45 MPH WHERE TERRAIN HAS BOOSTED THE WINDS AT CMX. SUNSHINE WITH TEMPS INTO THE LOWER TO MID 70S AND DEEP MIXING TO AROUND 750 MB HAS LOWERED DEWPOINTS TO AROUND 30F WITH RH VALUES TO AROUND 20 PCT. THE COMBINATION OF THE DRY AIR WINDS HAS RESULTED IN CRITICAL FIRE WEATHER CONDITIONS. TONIGHT...AS THE PRES GRADIENT WEAKENS AND DAYTIME HEATING SUBSIDES...WINDS WILL DIMINISH QUICKLY THIS EVENING AND BECOME LIGHT OVERNIGHT. HIGHER RES SHORT RANGE MODELS SUGGEST THAT THE BEST CHANCES OF PCPN ASSOCIATED WITH THE MANITOBA SHORTWAVE OVER THE SW HALF OF UPPER MI. EVEN THERE...WITH DRY LOW LEVELS AND WEAK FORCING WITH THE SHRTWV MAINLY JUST SPRINKLES AT MOST WOULD BE EXPECTED. SO...ONLY A SMALL AREA OF SLIGHT CHANCE POPS WERE INCLUDED. THURSDAY...EXPECT COOLER CONDITIONS OVER THE NORTH HALF OF UPPER MI WITH NRLY WINDS BEHIND A COLD FRONT MOVING THROUGH THE AREA LATE TONIGHT. WITH 850 MB TEMPS RANGING FROM AROUND 4C NORTH TO TO 9C SOUTH...TEMPS SHOULD RANGE FROM THE LOWER 50S NEAR LAKE SUPERIOR TO THE LOWER 70S INLAND SOUTHWEST. SUNSHINE AND FAVORABLE MIXING WILL AGAIN DROP DEWPOINTS INTO THE LOWER 30S WITH RH VALUES TO AROUND 25 PERCENT SOUTH. HOWEVER...WITH WINDS ONLY TO AROUND 10 MPH...THE WILDFIRE RISK WILL BE LOWER THAN TODAY. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 429 AM EDT WED MAY 15 2013 TO START THE LONG TERM...AT 12Z THU...SFC AND UPPER RIDGE WILL BE MOVING INTO THE CWA FROM THE NW...STICKING AROUND THROUGH FRI. THIS WILL CREATE MOSTLY SUNNY SKIES FOR THE MOST PART THU THROUGH FRIDAY. EXPECT HIGHS IN THE 60S AND 70S FOR THE LAST 2 DAYS OF THE WORK WEEK. AN UPPER TROUGH MOVING INTO THE WRN CONUS AND DEEPENING SFC LOW PRESSURE OVER THE PLAINS STATES WILL DRAW A FRONTAL ZONE NORTHWARD TO NEAR THE CWA FOR SAT AND SUN. THIS WILL BRING PRECIP CHANCES TO THE CWA...BUT MOST MODELS SHOW PRECIP EITHER N OR S OF THE CWA OR A COMBINATION THEREOF. DECREASED POPS FOR THIS TIME PERIOD AS MODELS HAVE POOR AGREEMENT AND RUN TO RUN CONTINUITY WITH THE EVER VOLATILE CONVECTION. EXPECT TEMPS TO BE SIMILAR TO THU AND FRI IN THE 60S AND 70S. MON INTO THE MIDDLE OF NEXT WEEK...MODELS SHOW THE SYSTEM CLOSING OFF OVER MN AND EVENTUALLY MOVING ACROSS OR NEAR THE CWA...BUT UNCERTAINTY REMAINS HIGH GIVEN POOR MODEL AGREEMENT AND POOR RUN TO RUN CONTINUITY WITH THE SYSTEM AND ASSOCIATED PRECIP. CONVECTION IS ESPECIALLY HARD TO PINPOINT AT THIS TIME FRAME...FURTHER DECREASING CONFIDENCE. TEMPS SHOULD COOL DOWN A BIT MOVING INTO MID WEEK IF THE UPPER LOW DOES INDEED MOVE TOWARD OR OVER THE CWA. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 149 PM EDT WED MAY 15 2013 VFR CONDITIONS ARE EXPECTED TO PREVAIL AT ALL THREE TAF SITES THROUGH THE FORECAST PERIOD. EXPECT WNW WINDS TO GUST OVER 20 KTS AT ALL THE SITES TODAY...STRONGEST AT KCMX AND KSAW. ONLY SKY COVER WILL BE SCT-BKN MID CLOUDS...ESPECIALLY THIS AFTERNOON AND EVENING. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 409 PM EDT WED MAY 15 2013 EXPECT WINDS WITH GUSTS 25 KNOTS TO DIMINISH TONIGHT AS HIGH PRES BUILDS INTO THE REGION. HIGH PRESSURE WILL EXPAND ACROSS GREAT LAKES INTO THE WEEKEND WITH EAST-SOUTHEAST WINDS AT OR BLO 25 KTS. WINDS BECOME SOUTHERLY LATE THIS WEEKEND AHEAD OF LOW PRESSURE TROUGH PUSHING IN FROM NORTHERN PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... RED FLAG WARNING UNTIL 9 PM EDT /8 PM CDT/ THIS EVENING FOR MIZ002-004>006-009>014-084-085. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...TITUS AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
140 AM EDT WED MAY 15 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 422 PM EDT TUE MAY 14 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A ZONAL MID/UPPER LEVEL PATTERN ACROSS THE NRN CONUS WITH A PROMINENT SHORTWAVE TROUGH NEAR WINNIPEG. AT THE SFC...A 992 MB LOW WAS ALSO LOCATED OVER SE MANITOBA WITH A COLD FRONT THROUGH NW MN INTO ERN SD. A WARM FRONT STRETCHED FROM CNTRL MN INTO SRN WI. RADAR INDICATED WEAK RETURNS WITH VERY LIGHT SHOWERS(VIRGA OR SPRINKLES) THROUGH CNTRL UPPER MI AS THE BAND OF 310K (750-600 MB)ISENTROPIC LIFT MOVES THROUGH THE AREA. SATELLITE SHOWED SKIES CLEARING OVER THE WEST AS DRIER AIR BEHIND THE PCPN BAND MOVES IN. TONIGHT...MODELS SUGGEST THAT AS THE MID LEVEL SHRTWV TROUGH AND ASSOCIATED SFC TROUGH MOVES THROUGH UPPER MI SOME SHOWERS MAY DEVELOP...MAINLY ACROSS NRN LAKE SUPERIOR AND POSSIBLY INTO THE NRN PORTIONS OF UPPER MI ON THE SRN TAIL OF THE STRONGER QVECTOR CONV AND FAVORABLE ISENTROPIC ASCENT JUST AHEAD OF THE SFC TROUGH. MUCAPE VALUES (LIFTING FROM NEAR 750 MB) OF 500-1000 J/KG STILL SUPPORT A CONDITIONAL THREAT OF TSRA. ALTHOUGH EFFECTIVE SHEAR VALUES ARE MARGINAL (20-30 KT) SOME SMALL HAIL MAY BE POSSIBLE WITH ANY TSRA THAT DEVELOP. CONFIDENCE IN SHRA/TSRA DEVELOPMENT IS LIMITED AS MODELS HAVE TRENDED TOO HIGH WITH LOW LEVEL MOISTURE AVAILABILITY. SO...ONLY LOWER END CHANCE POPS WERE INCLUDED. WED...MODEL SOUNDINGS SHOW STRONG MID-LVL DRYING/SUBSIDENCE IN THE WAKE OF THE COLD FRONT AS 850 MB TEMPS DROP TO AROUND 5C EARLY WED BUT REBOUND TO TO AROUND 8C-9C WED AFTERNOON. MIXING HEIGHTS ABOVE 800 MB SHOULD MIX A SIGNIFICANT ENOUGH PORTION OF THE VERY DRY 800-650 MB LAYER TO DROP DEWPOINTS INLAND TO AROUND 30F. WITH TEMPS INTO THE LOWER TO MID 70S...RH VALUES WILL DROP TO AROUND 20 PERCENT. NW WIND SHOULD ALSO INCREASE TO AROUND 15 MPH WITH GUSTS OF 20-25 MPH IN THE AFTERNOON. SO...A FIRE WEATHER WATCH WAS ISSUED FOR MOST OF INLAND WEST AND CENTRAL UPPER MICHIGAN. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 444 PM EDT TUE MAY 14 2013 OUR STRONGER WINDS WILL QUICKLY DIMINISH WEDNESDAY NIGHT...EVEN WITH A REINFORCING SFC TROUGH STRETCHED W-E OVER LAKE SUPERIOR AT 06Z THURSDAY SINKING SE ACROSS EASTERN UPPER MI BY 12Z THURSDAY. WITH THAT RH VALUES SHOULD QUICKLY REBOUND TO 35 PERCENT OR BETTER BY 03Z THURSDAY. BEHIND THE EXITING TROUGH...HIGH PRESSURE SITUATED OVER S CENTRAL CANADA WEDNESDAY NIGHT WILL PUSH ACROSS THE CWA AND BE DIRECTLY OVERHEAD DURING THE DAY THURSDAY...BEFORE SLOWLY EXITING EASTERN UPPER MI/LAKE SUPERIOR THURSDAY NIGHT INTO FRIDAY. THURSDAY WILL BE DRY ONCE AGAIN FOR SOUTH CENTRAL AREAS...AND IN PARTICULAR GOGEBIC...ONTONAGON...IRON...AND DICKINSON COUNTIES. WINDS WILL BE MUCH LIGHTER THAN WEDNESDAY GIVEN THE DIMINISHED PRESSURE GRADIENT...AVERAGING 5-10KTS. A WILDFIRE POTENTIAL STATEMENT MAY BE NEEDED...BUT IS REALLY MARGINAL GIVEN THE NEAR NORMAL TEMPS FOR THIS TIME OF YEAR...AND LIGHTER WINDS. THE WINDS ARE THE MAIN THREAT THIS TIME OF YEAR...GIVEN THAT THE MAIN CARRIER OF FIRES IS THE DRY GRASSES. THE LINGERING HIGH OVER THE EAST WILL KEEP DRIER AIR IN PLACE...LIMITING THE POTENTIAL FOR ANY SHOWERS TO MOVE MUCH EAST OF A LINE FROM MQT TO ESC UNTIL SATURDAY MORNING. EXPECT INCREASED S FLOW STARTING FRIDAY NIGHT...IN ADVANCE OF A NEARING LOW DEVELOPING ACROSS THE CENTRAL PLAINS STATES. SEVERAL WARMER NIGHTS ARE FIGURED WITH MID 40S FOR LOWS FRIDAY NIGHT...NEAR 50F SATURDAY NIGHT AND AGAIN SUNDAY NIGHT. THE LATEST TREND IS TO MINIMIZE THE POTENTIAL FOR THUNDERSTORM ACTIVITY UNTIL THE SFC LOW AND 500MB TROUGH GET A BIT CLOSER TO THE CWA...AROUND OR AFTER THE SUNDAY TIME PERIOD. EXPECT THE ELONGATED LOW STRETCHING FROM NORTHEAST MN TO N TX AT 18Z SUNDAY /ECMWF FARTHEST EAST/ TO CONSOLIDATE OVER WESTERN UPPER MICHIGAN SUNDAY EVENING. THE 12Z GFS DOES NOT BRING THE LOW TO WESTERN UPPER MI UNTIL TUESDAY. NEEDLESS TO SAY THIS WILL BE A SLOW MOVING SYSTEM...WITH SEVERAL ROUNDS OF PRECIP ROTING INTO THE REGION. WILL GO WITH A MODEL CONSENSUS BEYOND SUNDAY...GIVEN THE LARGER DISCREPANCIES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 139 AM EDT WED MAY 15 2013 VFR CONDITIONS SHOULD PREVAIL AT ALL THREE TAF SITES THROUGH THE FORECAST PERIOD. WILL GET GUSTY THROUGH THE MORNING AT ALL SITES. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 422 PM EDT TUE MAY 14 2013 SOUTHERLY FLOW WAS INCREASING AHEAD OF A LOW PRESSURE SYSTEM MOVING EAST THROUGH SOUTHERN CANADA. WINDS INCREASE TO 25 KTS TONIGHT INTO WED BUT WILL BE LIMITED AS LOW LEVEL WARM AIR ADVECTION RESULTS IN INCREASING STABILITY. WINDS ARE EXPECTED TO REMAIN BELOW 30KTS LATER THIS WEEK AND INTO THE WEEKEND. AFTER COOL AND WINTRY WEATHER FOR THE SPRING SO FAR...SUMMERTIME WEATHER IS BECOMING MORE COMMON. THUNDERSTORMS ARE POSSIBLE TONIGHT AND ENDING BY EARLY WEDNESDAY. ANOTHER ROUND OF THUNDERSTORMS WILL BE POSSIBLE WEST ON SATURDAY/SATURDAY NIGHT...AND ACROSS ALL OF LAKE SUPERIOR SUNDAY THROUGH MONDAY MORNING. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... FIRE WEATHER WATCH FROM 1 PM EDT /NOON CDT/ THIS AFTERNOON THROUGH THIS EVENING FOR MIZ002-004>006-009>014-084-085. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...KF AVIATION...07 MARINE...JLB
AREA FORECAST DISCUSSION
NWS DULUTH MN
139 AM CDT WED MAY 15 2013 .AVIATION...06Z TAF ISSUANCE. HIGH PRESSURE WILL BRING VFR CONDITIONS FOR THE OVERNIGHT HOURS...ALONG WITH SOME GUSTY WINDS BEHIND A DEPARTING COLD FRONT. THE WINDS WILL LOSE THEIR GUSTS FOR THE MOST PART OVERNIGHT...BUT WILL PICK UP AGAIN ON WEDNESDAY WITH DAYTIME HEATING. THERE COULD ALSO BE A FEW SHOWERS DEVELOPING AS A WEAK SYSTEM DROPS ACROSS THE REGION. THE SHOWERS WILL RESULT IN ERRATIC WINDS WITH THE PASSAGE OF THE SHOWERS. && .PREV DISCUSSION... /ISSUED 922 PM CDT TUE MAY 14 2013/ UPDATE...HAS BEEN A BUSY EVENING PROVIDING WEATHER SUPPORT FOR THE WILDFIRE OVER THE EASTERN DOUGLAS COUNTY/WESTERN BAYFIELD COUNTY LINE AREA. THE PRECIPITATION MAINLY STAYED NORTH OF THE CWA THIS AFTERNOON AND EVENING. THE BIG STORY IS DEFINITELY THE WILDFIRE...WHICH DEVELOPED RAPIDLY AND RESULTED IN ONGOING EVACUATIONS. TEMPERATURES APPROACHED 90 DEGREES IN THAT AREA THIS AFTERNOON WITH GUSTY SOUTHWEST WINDS. THE BIG CONCERN WAS THE PASSAGE OF A COLD FRONT...WHICH SHIFTED WINDS TO THE WEST DURING THE EVENING. FORTUNATELY THE INTENSE WINDS THAT MOVED ACROSS MUCH OF MN DID NOT MAKE IT TOO FAR INTO WI BEFORE WINDS STARTED TO DIMINISH THIS EVENING. THE DLHWRF...RAP AND HRRR ALL HAD A REALLY GOOD HANDLE ON THE WINDS AND WE DETAILED THAT IN A COUPLE UPDATES TO THE FIRE WEATHER SPOT FORECAST. PREV DISCUSSION... /ISSUED 700 PM CDT TUE MAY 14 2013/ AVIATION.../00Z TAF ISSUANCE/ A COLD FRONT WILL MOVE ACROSS THE NORTHLAND TONIGHT...RESULTING IN VFR CONDITIONS BUT GUSTY WESTERLY WINDS. PREV DISCUSSION... /ISSUED 341 PM CDT TUE MAY 14 2013/ SHORT TERM...SFC FRONT LOCATED JUST WEST OF CWA AS OF MID AFTERNOON. INITIAL CONVECTIVE AREA HAS SHIFTED WELL EAST OF CWA WITH STRONG WARM ADVECTION OCCURRING. MAX TEMPS HAVE REACHED MID TO UPPER 80S ACROSS SWRN AND SRN MN CWA... AND LOW 80S INTERIOR WISC ZONES. MID 40S ARE COMMON ALONG LAKE SUPERIOR AS ONSHORE FLOW PREVAILS DUE TO LARGE THERMAL GRADIENT. AHEAD OF FRONT A RELATIVE MOIST AXIS EXISTS FROM KOOCH COUNTY SOUTH TO CASS COUNTY WITH DEWPOINTS MID 40S TO 50. CONVECTION TRYING TO ORGANIZE ACROSS NRN KOOCH INTO ONTARIO AS AN AREA OF MUCAPE NEAR 500 J/KG HAS DEVELOPED. HAVE KEPT LOW POPS ALONG BORDERLAND INTO ARROWHEAD UNTIL FROPA LATE TODAY OR THIS EVENING. REMOVED POPS OVER WISC AS CONVECTIVE INHIBITION APPEARS TO BE TOO STRONG. TONIGHT...FRONTAL SYSTEM WILL USHER IN GUSTY WEST AND NORTHWEST WINDS THIS EVENING. WINDS COULD BE STRONG OVER NRN HALF OF MN CWA THROUGH MID EVENING. MIXING POTENTIAL SHOULD CONTINUE OVER MOST OF THE CWA THROUGH THE NIGHT SO MAY HAVE TO WATCH OVERNIGHT MINS FOR COLD BIAS. TOMORROW...A PLEASANT DAY AHEAD IN TERMS OF SUNSHINE AND MILD READINGS. GUSTY WINDS WILL DEVELOP BY MID MORNING AS MOMENTUM TRANSFER OCCURS IN A LOW SHEAR BDRY LYR. FIRE DANGER INCREASING OVER ARROWHEAD AND WISC AS LOW RH/WARM AIR COMBINE TO INCREASE THREAT. LIMITING FACTOR WOULD APPEAR TO BE SUFFICIENT WINDS. LONG TERM [WEDNESDAY NIGHT - MONDAY]... THE BEGINNING OF THE PERIOD LOOKS DRY AS HIGH PRESSURE OVER ONTARIO AND THE GREAT LAKES HELP PROMOTE DRY AND RELATIVELY CLEAR WEATHER FOR WEDNESDAY NIGHT AND THURSDAY. THERE IS A REMOTE POSSIBILITY OF PCPN WEDNESDAY NIGHT DUE TO A POTENTIAL STALLED TRAILING SECONDARY COLD FRONT IN THE WAKE OF THE LOW PRESSURE SYSTEM MOVING THROUGH TODAY. HOWEVER...SINCE THIS SEEMS SO REMOTE...KEPT THE WEDNESDAY NIGHT FORECAST DRY. IT STILL LOOKS LIKE THURSDAY NIGHT AND THROUGH THE WEEKEND WILL BE RATHER ACTIVE WITH PERIODS OF SHOWERS AND THUNDERSTORMS AS A MID/UPPER LEVEL RIDGE MOVES INTO AND THROUGH THE PLAINS AND UPPER MIDWEST. THE MOST ACTIVE PERIOD MAY BE LATE IN THE WEEKEND AND EARLY NEXT WEEK WHEN A STRONG LOW PRESSURE SYSTEM POSSIBLY MOVES THROUGH THE UPPER MIDWEST. DETAILS ARE HARD TO DETERMINE DUE TO SIGNIFICANT DIFFERENCES BETWEEN EACH MODEL...AND FROM RUN TO RUN...BUT THE OVERALL THEME OF A PROLONGED WET PERIOD LOOKS SIMILAR. AN OPEN GULF OF MEXICO WILL ALLOW PLENTY OF MOISTURE TO WORK ITS WAY NORTH TO THE UPPER MIDWEST. THE NORTHLAND COULD RACK UP SIGNIFICANT AMOUNTS OF RAINFALL OVER THE SPAN OF SEVERAL DAYS...POSSIBLY MORE THAN A FEW INCHES IN AREAS. THIS COULD RESULT IN RISES ALONG AREA STREAMS AND RIVERS. TEMPERATURES WILL LIKELY BE ABOVE NORMAL FOR THURSDAY AND FRIDAY...AND THEN TREND TOWARDS NORMAL INTO EARLY NEXT WEEK. AVIATION.../18Z TAF ISSUANCE/ MOSTLY CLEAR SKIES AND VFR CONDITIONS ARE RETURNING TO NE MINNESOTA AND NW WISCONSIN EARLY THIS AFTERNOON IN THE WAKE OF MORNING RAIN SHOWERS THAT MOVED THROUGH THE REGION. THE WINDS WILL INCREASE THIS AFTERNOON AS A COLD FRONT IN THE FAR NW MINNESOTA AND THE EASTERN DAKOTAS APPROACHES THE NORTHLAND. THERE IS A SMALL CHANCE OF SHOWERS AND STORMS WITH THE PASSAGE OF THE COLD FRONT LATER THIS AFTERNOON. THE CANADIAN BORDER AND KINL AREA HAVE THE GREATEST CHANCE OF SEEING STORMS...SO I KEPT THE TEMPO GROUP AT KINL FOR -TSRA. I THINK IT IS VERY UNLIKELY THAT KBRD/KHYR/KDLH/KHIB WILL SEE ANY STORMS...BUT WE WILL NEED TO KEEP AN EYE ON STORM DEVELOPMENT ALONG THE COLD FRONT. THERE MAY A BRIEF PERIOD OF STRONG W WINDS OF 15 TO 20 KNOTS WITH GUSTS UP TO 30 KNOTS AT KBRD/KINL/KHIB LATE THIS AFTERNOON AND EARLY THIS EVENING IN THE WAKE OF THE COLD FRONT. && .POINT TEMPS/POPS... DLH 72 47 66 45 / 0 0 0 10 INL 71 41 70 44 / 0 10 0 20 BRD 76 48 76 51 / 0 0 10 30 HYR 74 45 75 47 / 0 0 10 20 ASX 72 44 65 43 / 0 0 0 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. && $$ AVIATION...DAP/MELDE
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
855 PM MDT Thu May 16 2013 .DISCUSSION... Update forthcoming. Have made adjustments to the pop and weather grids. Moist and unstable flow aloft continues ahead of an upper trof approaching from the west. Latest RUC analysis keeps overnight precipitation mainly over the southwest so have lowered pops across central and northern portions of the county warning area into Friday morning. Remainder of forecast looks on track. Emanuel && .AVIATION... UPDATED 0000Z. Moist and unstable flow will continue as an upper level trough moves slowly over the region from the west. Occasional disturbances will bring scattered to numerous showers to the southern half of Central Montana through 00z Friday. In the north VFR conditions should prevail tonight with areas of MVFR in and around showers before 12z. Most of Central Montana will see more widespread stratiform rain and mountain snow develop after 12z. Widespread MVFR/IFR conditions and mountain obscuration is expected. && .PREV DISCUSSION...Issued 257 PM MDT Thu May 16 2013 Thursday through Saturday...Moist flow aloft and multiple weak upper level disturbances will move across the area ahead of a low pressure trough that will move across the area throughout the weekend. Showers and afternoon thunderstorms will increase in coverage through the weekend. No severe thunderstorms are expected at this time however isolated strong gusty winds and hail will be possible. The area with the largest chance of widespread precipitation will continue to be Southwest Montana where low level moisture will be the most abundant throughout the period. Less chance of wide spread precipitation to the north as the Moist flow at mid level dramatically decreases north of the Little Belt Mountains. Suk SATURDAY NIGHT THROUGH THURSDAY...FAIRLY GOOD MODEL AGREEMENT THROUGH THE PERIOD. EXPECT AN UNSETTLED WEATHER PATTERN AS THE BROAD UPPER TROUGH...ALREADY IN PLACE...MOVES EASTWARD. ON TUESDAY WEAK RIDGING BUILDS INTO THE AREA. THE ECMWF HAS THE RIDGE BUILDING A LITTLE STRONGER NORTH INTO MONTANA...BUT THE RIDGING IS SHORT LIVED. BY TUESDAY NIGHT THE AREA HAS DIFFLUENT FLOW WHILE BETWEEN SYSTEMS. BY WEDNESDAY MORNING THE CWA WILL START TO FEEL THE EFFECTS OF THE LOW IN THE PAC NW. AS FAR AS PRECIPITATION GOES...MODEL SOUNDINGS CONTINUE TO SHOW DEEP MOISTURE THROUGH MONDAY MORNING...BUT NOT AS MUCH INSTABILITY. MOST OF PRECIPITATION WILL FALL AS RAIN WITH THE EXCEPTION OF THE HIGHEST OF ELEVATIONS. THIS WEEKEND`S SYSTEM WILL BRING MUCH NEEDED RAINFALL OVER MUCH OF THE STATE...WITH ADDITIONAL CHANCES BY THE END OF NEXT WEEK. MERCER && .PRELIMINARY POINT TEMPS/POPS... GTF 64 45 61 44 / 50 50 70 50 CTB 64 42 63 41 / 50 40 50 40 HLN 65 46 63 45 / 50 60 80 60 BZN 66 42 62 41 / 50 70 80 70 WEY 61 43 56 39 / 60 60 70 60 DLN 63 43 59 41 / 70 70 80 80 HVR 71 47 68 46 / 50 60 60 50 LWT 64 46 59 43 / 50 80 70 70 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS HASTINGS NE
558 PM CDT WED MAY 15 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 348 PM CDT WED MAY 15 2013 FORECAST COULD BE PRETTY COMPLICATED CONCERNING CHANCES OF PRECIPITATION FOR THE SHORT TERM. FOR STARTERS...A NEARLY STATIONARY BOUNDARY IN OUR FAR SOUTHERN CWA COULD BE THE FOCUS OF SOME AFTERNOON AND EVENING THUNDERSTORM ACTIVITY. SHEAR IS EXTREMELY WEAK AND INSTABILITY IS MARGINAL AT BEST. WE STILL HAVE INVERTED V SOUNDINGS...BUT NOT MIXING NEARLY AS HIGH AS YESTERDAY...AND AIR NOT NEARLY AS DRY. OUR MAIN CONCERN WOULD BE TO GET AN ISOLATED STRONG TO SEVERE WIND GUST...BUT THIS WOULD BE A LONGSHOT. WENT CLOSER WITH RAP FOR DEWPOINTS AND WIND WITHIN THE FIRST 6 TO 12 HOURS AS THE SOLUTIONS OF THIS MODEL HAVE BEEN SUPERIOR TO OTHERS. I HAD TO INCREASE THE TOP END OF WIND SPEEDS A BIT AS WE ARE MIXING A BIT BETTER THAN WHAT IS FORECAST...BUT AS THE FRONT EDGES NORTH...WIND SPEEDS SHOULD DECREASE ACROSS MUCH OF THE CWA. WENT TOWARD CONSRAW FOR DEWPOINTS AS WE GET CLOSER TO THE OVERNIGHT HOURS INTO THURSDAY. THERE IS A BIT OF A SIGNAL FOR SOME FOG TONIGHT FROM THE SREF SO WILL CONTINUE WITH MENTIONING OF PATCHY FOG...ESPECIALLY AS THE FRONT MOVES NORTH. THE FORECAST GETS A LITTLE MUDDLED TONIGHT FOR PRECIPITATION CHANCES. MODELS ARE GENERALLY LIFTING THE BOUNDARY TO THE NORTH AS A WARM FRONT. THERE WILL NOT BE MUCH OF A LOW-LEVEL JET TO SUSTAIN ANY CONVECTION THAT MIGHT FIRE UP THIS AFTERNOON AND EVENING. WITH DECREASING WITH SUNSET...MOST CONVECTION SHOULD DIE OUT. OVERNIGHT...HOWEVER...SOME MODELS ARE INDICATING THE POSSIBILITY OF MORE CONVECTION MAINLY IN THE NORTHERN CWA. THE NMM INDICATES A POSSIBLE SMALL-SCALE MCS DEVELOP OVER THE CWA OF LBF AND FOLLOW THE BOUNDARY TO THE EAST ACROSS THE NORTHERN CWA...WHICH MAY POSSIBLY LAST INTO THE EARLY MORNING HOURS. THEN ANOTHER LULL IS LIKELY BY LATE MORNING THURSDAY INTO EARLY AFTERNOON AS THE BOUNDARY TO THE NORTH EITHER CONTINUES TO LIFT NORTH OR WASHES OUT...DEPENDING ON WHICH SOLUTION IS REALIZED. EITHER WAY...A LULL IS LIKELY. A MID-LEVEL PERTURBATION IS STILL FORECAST TO MOVE EAST ACROSS THE AREA BY THURSDAY AFTERNOON...BUT AMPLITUDE SHOULD REMAIN QUITE LOW. AS A THETA E RIDGE SHIFTS EAST...ALONG WITH THE WEAK PERTURBATION...WE SHOULD HAVE A GOOD SHOT OF SOME SHOWERS AND THUNDERSHOWERS...ESPECIALLY WEST/INTO CENTRAL PARTS OF THE CWA. MUCAPES WILL BE HIGH ENOUGH TO SUSTAIN THUNDERSTORMS...BUT SHEAR WILL BE WEAK ONCE AGAIN...SO SEVERE WEATHER WOULD NOT BE OUT OF THE QUESTION...BUT CERTAINLY NO OUTBREAK IS ANTICIPATED. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 348 PM CDT WED MAY 15 2013 FOCUS OF THE LONG TERM PERIOD WILL CENTER AROUND CHANCES FOR THUNDERSTORMS...SOME OF WHICH MIGHT BE POSSIBLY SEVERE AT TIMES...MAINLY SATURDAY AFTERNOON THROUGH SUNDAY EVENING. THE CUTOFF LOW ACROSS THE DESERT SOUTHWEST WILL FINALLY BEGIN TO INGEST BACK INTO THE MEAN FLOW THROUGHOUT THE SHORT TERM...FINALLY SHIFTING OFF TO THE SOUTHEAST ACROSS MISSOURI AND ARKANSAS BY THURSDAY NIGHT. THROUGH THE OVERNIGHT PERIODS...A WEAK UPPER LEVEL DISTURBANCE WILL BEGIN TO SHIFT ACROSS THE PLAINS...ON THE BACKSIDE OF THE UPPER LEVEL LOW. MODELS DISAGREE ON THE DEPTH OF THE WAVE...WITH THE ECMWF...UKMET AND NAM SOLUTIONS A BIT MORE SHALLOW THAN THE DEEPER PROGRESSIVE GFS. AT THE SURFACE...MODELS INDICATE A A DEVELOPING TROUGH ALONG THE FRONT RANGE OF THE ROCKIES...WITH SOME SORT OF FRONT...WASHED OUT BOUNDARY SHIFTING NORTH OF THE OUTLOOK AREA. COMBINED WITH THE WAVE AND WARM AIR ADVECTION...MODELS CONTINUE TO HINT AT AT LEAST A CHANCE FOR PRECIPITATION...WITH THE GFS HEDGING FURTHER SOUTH INTO KANSAS. AT THIS POINT...REALLY NOT BUYING INTO THE SOUTHERN SOLUTION AND TRENDING MORE TOWARDS A NEBRASKA RAIN EVENT. AFTER THE PASSAGE OF THE UPPER LEVEL WAVE...SUBSIDENCE TAKES HOLD...AND CURRENT THINKING IS THAT MUCH OF FRIDAY DURING THE DAY WILL BE DRY. HOWEVER...BY FRIDAY AFTERNOON AND EVENING...ANOTHER UPPER LEVEL TROUGH WILL BEGIN TO SHIFT INTO THE AREA. WITH THE EASTWARD PROGRESSION OF THE TROUGH...HEIGHT FALLS...AND A SURFACE LEESIDE TROUGH...ITS POSSIBLE WESTERN PORTIONS OF NEBRASKA COULD SEE SOME CONVECTION FRIDAY AFTERNOON. A FAIRLY DECENT LLJ IS EXPECTED TO DEVELOP ACROSS WESTERN AREAS AND SHIFT EASTWARD OVERNIGHT. THIS COMBINED WITH A DECENT THETA E RIDGE OVER THE OUTLOOK AREA...WENT AHEAD AND CONTINUED AT LEAST SLIGHT POPS OVERNIGHT. SHOULD STORMS DEVELOP...THERE IS PLENTY OF INSTABILITY TO WORK WITH...ABOUT 2000-3000 J/KG. HOWEVER...A STRONG CAP EXISTS WITH 700 MB TEMPERATURES NEAR 10 TO 11 DEGREES...AND BULK SHEAR IS LIMITED AROUND 20 TO 30 KTS. SATURDAY LOOKS TO BE THE MAIN FOCUS OF THE MID TERM PERIOD...AS THE UPPER LEVEL LOW SHIFTS EASTWARD. BY SATURDAY AFTERNOON...THE SURFACE TROUGH BECOMES ELONGATED ALONG THE FRONT RANGE. BOTH THE GFS AND ECMWF SOLUTIONS HAVE BEGUN TO TREND A BIT SLOWER IN PREVIOUS RUNS...BRINGING IN CHANCES FOR PRECIPITATION ACROSS THE WEST...MAINLY DURING LATE AFTERNOON AND EVENING. INSTABILITY IS QUITE HIGH DURING THE SATURDAY AFTERNOON PERIOD THROUGH OVERNIGHT...WITH 4000 TO 5000 J/KG POSSIBLE. AGAIN...AS HAS BEEN THE CASE MOST OF THIS WEEK...700 MB TEMPERATURES ARE ON THE ORDER OF 10 TO 12 AND EVEN 13 DEGREES AT TIMES. 0 TO 6 KM BULK SHEAR IS ALSO AT ITS HIGHEST SATURDAY EVENING...CLIMBING TO NEAR 30 TO 40 KTS...WITH 50 KTS EXPECTED FURTHER WEST. BY SUNDAY AFTERNOON...THE SURFACE TROUGH AND FRONTAL BOUNDARY WILL FINALLY MIGRATE EASTWARD ACROSS THE CWA. THIS WILL GIVE US YET ANOTHER CHANCE FOR PRECIPITATION...POSSIBLY SEVERE AS THE CWA REMAINS SITUATED JUST ON THE EASTERN FRINGE OF THE UPPER LEVEL TROUGH. THE ECMWF SOLUTIONS TENDS TO BE A BIT MORE PROGRESSIVE THAN THE GFS SOLUTION WITH A CLOSED LOW ACROSS NORTHERN NEBRASKA BY 0Z MONDAY...WHILE THE GFS REMAINS CLOSED OVER THE PANHANDLE. SEVERE IS BEGINNING TO LOOK POSSIBLE ALSO ON SUNDAY. INSTABILITY DOES NOT LOOK QUITE AS STRONG AS SATURDAY BUT STILL IS NEAR 2000 J/KG OF MOST UNSTABLE CAPE. HOWEVER...THE CAP IS ALSO NOT QUITE AS STRONG WITH 700 MB TEMPERATURES ON THE ORDER OF 6 TO 7 DEGREES CELSIUS. THEREFORE...SEVERE STORMS DO NOT LOOK OUT OF THE QUESTION FOR SUNDAY AFTERNOON. THROUGH THE REST OF THE LONG TERM...THE UPPER LEVEL LOW SPINS ACROSS THE PLAINS GENERATING CHANCES FOR PRECIPITATION THROUGH MONDAY. HOWEVER...AN UPPER LEVEL RIDGE LOOKS TO SLOWLY BEGIN TO BUILD ACROSS THE DESERT SOUTHWEST TOWARDS THE BEGINNING OF NEXT WEEK. AS SUCH...THE UPPER LEVEL LOW EJECTS NORTHWARD...WITH PRECIPITATION QUICKLY EXITING THE REGION. DECIDED TO PULL OUT ANY SLIGHT MENTION OF PRECIPITATION ALONG THE FRINGES OF THE CWA AS THE CWA SEEMS TO BECOME DRY SLOTTED BY MONDAY NIGHT. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 558 PM CDT WED MAY 15 2013 VFR CONDITIONS EXPECTED THROUGH THE NEXT 24 HOURS...WITH CONVECTIVE ACTIVITY ALSO POSSIBLE. INCREASING HIGH LEVEL CLOUDS...WITH BASES NEAR 20000FT AGL...WILL BE OBSERVED DURING THE TAF PERIOD. A SCATTERED CUMULUS FIELD...WITH BASES NEAR 6000FT AGL...WILL ALSO LIKELY BE OBSERVED IN THE AREA THURSDAY AFTERNOON. ISOLATED TO SCATTERED CONVECTION WILL BE POSSIBLE NEAR THE TERMINAL TONIGHT...PRIMARILY AFTER 06Z...BUT THE PROBABILITY OF MEASURABLE PRECIPITATION BEING REALIZED AT KGRI IS TOO LOW FOR INSERTION INTO THE TAF AT THIS TIME. A BETTER CHANCE FOR SCATTERED CONVECTION IS FORECAST AT AND NEAR KGRI THURSDAY AFTERNOON...WHICH MAY IN TURN PROVIDE MEASURABLE PRECIPITATION TO THE TERMINAL. THAT BEING SAID...CONFIDENCE IS ONLY HIGH ENOUGH TO PROVIDE VCTS STARTING 21Z THURSDAY...FOR THE TIME BEING. THERE IS AN OUTSIDE CHANCE OF PATCHY FOG DEVELOPMENT AROUND SUNRISE THURSDAY...BUT THE PROBABILITY OF VISIBILITY RESTRICTION BEING REALIZED AT THE TERMINAL IS TOO LOW FOR INSERTION INTO THE TAF AT THIS TIME. THE SURFACE WIND WILL REMAIN FROM THE EAST...SUSTAINED AT AROUND 12KTS...TO START THE TAF PERIOD...BECOMING LIGHT AND VARIABLE TONIGHT AND THEN BECOMING ESTABLISHED FROM THE SOUTHEAST AT AROUND 12KTS DURING THE DAY THURSDAY. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...HEINLEIN LONG TERM...SALTZMAN AVIATION...BRYANT
AREA FORECAST DISCUSSION
NWS HASTINGS NE
353 PM CDT WED MAY 15 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 348 PM CDT WED MAY 15 2013 FORECAST COULD BE PRETTY COMPLICATED CONCERNING CHANCES OF PRECIPITATION FOR THE SHORT TERM. FOR STARTERS...A NEARLY STATIONARY BOUNDARY IN OUR FAR SOUTHERN CWA COULD BE THE FOCUS OF SOME AFTERNOON AND EVENING THUNDERSTORM ACTIVITY. SHEAR IS EXTREMELY WEAK AND INSTABILITY IS MARGINAL AT BEST. WE STILL HAVE INVERTED V SOUNDINGS...BUT NOT MIXING NEARLY AS HIGH AS YESTERDAY...AND AIR NOT NEARLY AS DRY. OUR MAIN CONCERN WOULD BE TO GET AN ISOLATED STRONG TO SEVERE WIND GUST...BUT THIS WOULD BE A LONGSHOT. WENT CLOSER WITH RAP FOR DEWPOINTS AND WIND WITHIN THE FIRST 6 TO 12 HOURS AS THE SOLUTIONS OF THIS MODEL HAVE BEEN SUPERIOR TO OTHERS. I HAD TO INCREASE THE TOP END OF WIND SPEEDS A BIT AS WE ARE MIXING A BIT BETTER THAN WHAT IS FORECAST...BUT AS THE FRONT EDGES NORTH...WIND SPEEDS SHOULD DECREASE ACROSS MUCH OF THE CWA. WENT TOWARD CONSRAW FOR DEWPOINTS AS WE GET CLOSER TO THE OVERNIGHT HOURS INTO THURSDAY. THERE IS A BIT OF A SIGNAL FOR SOME FOG TONIGHT FROM THE SREF SO WILL CONTINUE WITH MENTIONING OF PATCHY FOG...ESPECIALLY AS THE FRONT MOVES NORTH. THE FORECAST GETS A LITTLE MUDDLED TONIGHT FOR PRECIPITATION CHANCES. MODELS ARE GENERALLY LIFTING THE BOUNDARY TO THE NORTH AS A WARM FRONT. THERE WILL NOT BE MUCH OF A LOW-LEVEL JET TO SUSTAIN ANY CONVECTION THAT MIGHT FIRE UP THIS AFTERNOON AND EVENING. WITH DECREASING WITH SUNSET...MOST CONVECTION SHOULD DIE OUT. OVERNIGHT...HOWEVER...SOME MODELS ARE INDICATING THE POSSIBILITY OF MORE CONVECTION MAINLY IN THE NORTHERN CWA. THE NMM INDICATES A POSSIBLE SMALL-SCALE MCS DEVELOP OVER THE CWA OF LBF AND FOLLOW THE BOUNDARY TO THE EAST ACROSS THE NORTHERN CWA...WHICH MAY POSSIBLY LAST INTO THE EARLY MORNING HOURS. THEN ANOTHER LULL IS LIKELY BY LATE MORNING THURSDAY INTO EARLY AFTERNOON AS THE BOUNDARY TO THE NORTH EITHER CONTINUES TO LIFT NORTH OR WASHES OUT...DEPENDING ON WHICH SOLUTION IS REALIZED. EITHER WAY...A LULL IS LIKELY. A MID-LEVEL PERTURBATION IS STILL FORECAST TO MOVE EAST ACROSS THE AREA BY THURSDAY AFTERNOON...BUT AMPLITUDE SHOULD REMAIN QUITE LOW. AS A THETA E RIDGE SHIFTS EAST...ALONG WITH THE WEAK PERTURBATION...WE SHOULD HAVE A GOOD SHOT OF SOME SHOWERS AND THUNDERSHOWERS...ESPECIALLY WEST/INTO CENTRAL PARTS OF THE CWA. MUCAPES WILL BE HIGH ENOUGH TO SUSTAIN THUNDERSTORMS...BUT SHEAR WILL BE WEAK ONCE AGAIN...SO SEVERE WEATHER WOULD NOT BE OUT OF THE QUESTION...BUT CERTAINLY NO OUTBREAK IS ANTICIPATED. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 348 PM CDT WED MAY 15 2013 FOCUS OF THE LONG TERM PERIOD WILL CENTER AROUND CHANCES FOR THUNDERSTORMS...SOME OF WHICH MIGHT BE POSSIBLY SEVERE AT TIMES...MAINLY SATURDAY AFTERNOON THROUGH SUNDAY EVENING. THE CUTOFF LOW ACROSS THE DESERT SOUTHWEST WILL FINALLY BEGIN TO INGEST BACK INTO THE MEAN FLOW THROUGHOUT THE SHORT TERM...FINALLY SHIFTING OFF TO THE SOUTHEAST ACROSS MISSOURI AND ARKANSAS BY THURSDAY NIGHT. THROUGH THE OVERNIGHT PERIODS...A WEAK UPPER LEVEL DISTURBANCE WILL BEGIN TO SHIFT ACROSS THE PLAINS...ON THE BACKSIDE OF THE UPPER LEVEL LOW. MODELS DISAGREE ON THE DEPTH OF THE WAVE...WITH THE ECMWF...UKMET AND NAM SOLUTIONS A BIT MORE SHALLOW THAN THE DEEPER PROGRESSIVE GFS. AT THE SURFACE...MODELS INDICATE A A DEVELOPING TROUGH ALONG THE FRONT RANGE OF THE ROCKIES...WITH SOME SORT OF FRONT...WASHED OUT BOUNDARY SHIFTING NORTH OF THE OUTLOOK AREA. COMBINED WITH THE WAVE AND WARM AIR ADVECTION...MODELS CONTINUE TO HINT AT AT LEAST A CHANCE FOR PRECIPITATION...WITH THE GFS HEDGING FURTHER SOUTH INTO KANSAS. AT THIS POINT...REALLY NOT BUYING INTO THE SOUTHERN SOLUTION AND TRENDING MORE TOWARDS A NEBRASKA RAIN EVENT. AFTER THE PASSAGE OF THE UPPER LEVEL WAVE...SUBSIDENCE TAKES HOLD...AND CURRENT THINKING IS THAT MUCH OF FRIDAY DURING THE DAY WILL BE DRY. HOWEVER...BY FRIDAY AFTERNOON AND EVENING...ANOTHER UPPER LEVEL TROUGH WILL BEGIN TO SHIFT INTO THE AREA. WITH THE EASTWARD PROGRESSION OF THE TROUGH...HEIGHT FALLS...AND A SURFACE LEESIDE TROUGH...ITS POSSIBLE WESTERN PORTIONS OF NEBRASKA COULD SEE SOME CONVECTION FRIDAY AFTERNOON. A FAIRLY DECENT LLJ IS EXPECTED TO DEVELOP ACROSS WESTERN AREAS AND SHIFT EASTWARD OVERNIGHT. THIS COMBINED WITH A DECENT THETA E RIDGE OVER THE OUTLOOK AREA...WENT AHEAD AND CONTINUED AT LEAST SLIGHT POPS OVERNIGHT. SHOULD STORMS DEVELOP...THERE IS PLENTY OF INSTABILITY TO WORK WITH...ABOUT 2000-3000 J/KG. HOWEVER...A STRONG CAP EXISTS WITH 700 MB TEMPERATURES NEAR 10 TO 11 DEGREES...AND BULK SHEAR IS LIMITED AROUND 20 TO 30 KTS. SATURDAY LOOKS TO BE THE MAIN FOCUS OF THE MID TERM PERIOD...AS THE UPPER LEVEL LOW SHIFTS EASTWARD. BY SATURDAY AFTERNOON...THE SURFACE TROUGH BECOMES ELONGATED ALONG THE FRONT RANGE. BOTH THE GFS AND ECMWF SOLUTIONS HAVE BEGUN TO TREND A BIT SLOWER IN PREVIOUS RUNS...BRINGING IN CHANCES FOR PRECIPITATION ACROSS THE WEST...MAINLY DURING LATE AFTERNOON AND EVENING. INSTABILITY IS QUITE HIGH DURING THE SATURDAY AFTERNOON PERIOD THROUGH OVERNIGHT...WITH 4000 TO 5000 J/KG POSSIBLE. AGAIN...AS HAS BEEN THE CASE MOST OF THIS WEEK...700 MB TEMPERATURES ARE ON THE ORDER OF 10 TO 12 AND EVEN 13 DEGREES AT TIMES. 0 TO 6 KM BULK SHEAR IS ALSO AT ITS HIGHEST SATURDAY EVENING...CLIMBING TO NEAR 30 TO 40 KTS...WITH 50 KTS EXPECTED FURTHER WEST. BY SUNDAY AFTERNOON...THE SURFACE TROUGH AND FRONTAL BOUNDARY WILL FINALLY MIGRATE EASTWARD ACROSS THE CWA. THIS WILL GIVE US YET ANOTHER CHANCE FOR PRECIPITATION...POSSIBLY SEVERE AS THE CWA REMAINS SITUATED JUST ON THE EASTERN FRINGE OF THE UPPER LEVEL TROUGH. THE ECMWF SOLUTIONS TENDS TO BE A BIT MORE PROGRESSIVE THAN THE GFS SOLUTION WITH A CLOSED LOW ACROSS NORTHERN NEBRASKA BY 0Z MONDAY...WHILE THE GFS REMAINS CLOSED OVER THE PANHANDLE. SEVERE IS BEGINNING TO LOOK POSSIBLE ALSO ON SUNDAY. INSTABILITY DOES NOT LOOK QUITE AS STRONG AS SATURDAY BUT STILL IS NEAR 2000 J/KG OF MOST UNSTABLE CAPE. HOWEVER...THE CAP IS ALSO NOT QUITE AS STRONG WITH 700 MB TEMPERATURES ON THE ORDER OF 6 TO 7 DEGREES CELSIUS. THEREFORE...SEVERE STORMS DO NOT LOOK OUT OF THE QUESTION FOR SUNDAY AFTERNOON. THROUGH THE REST OF THE LONG TERM...THE UPPER LEVEL LOW SPINS ACROSS THE PLAINS GENERATING CHANCES FOR PRECIPITATION THROUGH MONDAY. HOWEVER...AN UPPER LEVEL RIDGE LOOKS TO SLOWLY BEGIN TO BUILD ACROSS THE DESERT SOUTHWEST TOWARDS THE BEGINNING OF NEXT WEEK. AS SUCH...THE UPPER LEVEL LOW EJECTS NORTHWARD...WITH PRECIPITATION QUICKLY EXITING THE REGION. DECIDED TO PULL OUT ANY SLIGHT MENTION OF PRECIPITATION ALONG THE FRINGES OF THE CWA AS THE CWA SEEMS TO BECOME DRY SLOTTED BY MONDAY NIGHT. && .AVIATION...(FOR THE 18Z KGRI TAF THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 348 PM CDT WED MAY 15 2013 WIND SHOULD DECREASE BY EARLY EVENING AS A FRONT TO THE SOUTH LIFTS NORTH. THERE IS AN OUTSIDE CHANCE OF A THUNDERSTORM...BUT THE FOCUS SHOULD BE TO THE SOUTH THROUGH EARLY EVENING...THEN TO THE NORTH DURING THE OVERNIGHT...WITH VCTS BY THURSDAY AFTERNOON COMING IN FROM THE WEST. VFR CONDITIONS ARE ANTICIPATED...WITH THE POSSIBILITY OF SOME MVFR DURING THE EARLY MORNING...BUT THIS IS A LONGSHOT...SO LEFT OUT OF THE FORECAST FOR NOW. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...HEINLEIN LONG TERM...SALTZMAN AVIATION...HEINLEIN
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1225 AM CDT WED MAY 15 2013 .UPDATE... ISSUED AT 1225 AM CDT WED MAY 15 2013 THE MAIN CHANGE WITH THIS ESTF UPDATE WAS TO INCREASE CLOUD COVER TO BETTER DEPICT CURRENT IR SATELLITE. SOME MINOR ADJUSTMENTS WILL BE NEEDED AS THE NGT PROGRESSES AS CLOUDS HAVE A GENERAL THINNING TREND THAT WILL NOT BE EASY TO FORESEE MUCH BEYOND A COUPLE HRS. WE ARE NOTING NEW TSTMS GOING UP JUST W OF THE FCST AREA. FOR NOW THE FCST IS DRY THE REST OF TNGT AND THE 03Z HRRR KEEPS S-CNTRL NEB DRY. HOWEVER...WE/VE ALSO SEEN COOLING CLOUD TOPS OVER NRN KS AND THE HRRR DOES DVLP SOME SHWRS. FOR NOW WE/LL CONTINUE TO MONITOR. WE WILL ALSO NEED TO WATCH FOR ISOLATED HEATBURSTS. UPDATE ISSUED AT 824 PM CDT TUE MAY 14 2013 OUTFLOW FROM EARLIER CONVECTION...ALONG WITH DECREASING DIABATIC HEATING...IS ALLOWING THE RELATIVE HUMIDITY TO CLIMB ACROSS THE ENTIRE CWA AT THIS HOUR. IN ADDITION...THE SURFACE WIND IS DECREASING IN INTENSITY. THESE TRENDS ARE EXPECTED TO CONTINUE THROUGH THE REST OF THE EVENING AND AS A RESULT...THE RED FLAG WARNING HAS BEEN CANCELLED. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 401 PM CDT TUE MAY 14 2013 FORECAST IS PRETTY MUCH ON TRACK. THE EXPECTED COLD FRONT IS SLICING SOUTHEAST ACROSS THE CWA WITH CONVECTION ALREADY TRYING TO FIRE ALONG IT. ANY SHOWERS OR THUNDERSTORMS WILL BE HIGH BASED WITH AN INVERTED V SOUNDING SCENARIO. THIS MEANS THAT THE LIKELY OUTCOME WILL BE LOW PRECIPITATION AND GUSTY WIND FROM CONVECTION. SHEAR IS WEAK AND MOISTURE IS LIMITED...SO ALL ONE WOULD EXPECT IS AN OUTSIDE CHANCE OF A SEVERE WIND GUSTS WITH THE INVERTED V SOUNDING SIGNATURE. THE FRONT WILL CONTINUE TO SLIDE SOUTH TONIGHT...BUT ANY INSTABILITY WILL WANE BY MID EVENING...SO CONVECTION SHOULD FOLLOW SUIT AND DIE OUT. STILL EXPECT THE FRONT TO STALL JUST SOUTH OF THE CWA FOR WEDNESDAY. ANY CONVECTION NEAR THE FRONT WILL BE LATE AFTERNOON AT THE EARLIEST...AND WOULD PROBABLY ONLY AFFECT THE EXTREME SOUTHERN CWA...SO KEPT CHANCES OF SHOWERS AND THUNDERSTORMS IN THE EXTREME SOUTH AND VERY LATE IN THE DAY. ALSO...COOLER TEMPERATURES ARE LAGGING BEHIND THE FRONT...SO INCREASED TEMPERATURES FOR WEDNESDAY FOR MOST LOCATIONS...EXCEPT PERHAPS ORD...WHICH STANDS A BETTER CHANCE OF BEING IN COOLER AIR. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 401 PM CDT TUE MAY 14 2013 THE MAIN FOCUS OF THE MID AND LONG TERM PERIODS WILL CENTER AROUND NUMEROUS CHANCES FOR THUNDERSTORMS...SOME OF WHICH MIGHT END UP BEING SEVERE. THERE IS PLENTY OF INSTABILITY THROUGHOUT MOST OF THE PERIOD...ALTHOUGH SEVERAL DAYS LIKELY REMAIN TOO CAPPED. BEGINNING WEDNESDAY NIGHT...THE UPPER LEVEL LOW WHICH HAS REMAINED MOSTLY CUT OFF ACROSS THE DESERT SOUTHWEST/NORTHWEST MEXICO REGION WILL FINALLY SHIFT NORTHEAST ACROSS OKLAHOMA...KANSAS AND MISSOURI. MODELS ARE IN FAIRLY GOOD AGREEMENT ON THIS TRACK OF THIS LOW PRESSURE SYSTEM. AT THE SURFACE...IT APPEARS A WARM FRONT WILL LIKELY LIFT NORTH BEFORE POSSIBLY WASHING OUT ACROSS PORTIONS OF NEBRASKA. AS A RESULT...INCREASED CLOUD COVER AND CONTINUED AT LEAST SLIGHT CHANCES FOR POPS INTO SOUTH CENTRAL NEBRASKA AS WELL THURSDAY MORNING. SREF PROBABILITIES INDICATES AT LEAST SOME CHANCE FOR FOG DEVELOPMENT...WHICH IS ALSO IN AGREEMENT WITH MODEL SOUNDINGS. THEREFORE...THREW IN AT LEAST PATCHY FOG ACROSS MUCH OF THE AREA. BY THURSDAY MORNING...LEFT SLIGHT CHANCES IN ACROSS THE ENTIRE AREA FOR LINGERING SHOWERS IN THE MORNING BUT EXPECT MOST PLACES TO REMAIN DRY DURING THAT 6 HOUR PERIOD. ON THE BACKSIDE OF THE UPPER LEVEL LOW...ANOTHER SHORTWAVE WILL SLIDE THROUGH THE REGION...POSSIBLY PROVIDING THE BEST CHANCES FOR PRECIPITATION THURSDAY AFTERNOON. MODELS ARE CONSISTENT WITH THIS SHORT WAVE TROUGH/PV ANOMALY SHIFTING ACROSS OUR NORTHERN CWA. THERE IS ALSO DECENT THETA E ADVECTION ACROSS OUR NORTHERN ZONES. THERE REMAINS PLENTY OF INSTABILITY ACROSS THE AREA ABOUT 1400 J/KG...WHILE 700 MB TEMPERATURES WILL LIKELY BE AROUND 6 CELSIUS. CERTAINLY CANNOT RULE OUT AN ISOLATED SEVERE THUNDERSTORM...MAINLY ACROSS WESTERN ZONES. BY FRIDAY...AN UPPER LEVEL RIDGE WILL BEGIN TO SHIFT ACROSS THE PLAINS...PROVIDING A MORE THAN LIKELY DRY DAY ACROSS THE PLAINS. HOWEVER...THAT BEING SAID...MODELS CONTINUE TO INDICATE VERY WEAK PERTURBATIONS SLIDING ACROSS THE UPPER LEVEL RIDGE FLOW DURING THE DAY ON FRIDAY. MODELS...SUCH AS THE NAM SOLUTION TRY TO HINT AT SOME LIGHTER SHOWERS POSSIBLY EVEN DRIZZLE AROUND. DECIDED TO LEAVE IN SLIGHT CHANCES MAINLY ACROSS KANSAS BEFORE SHIFTING NORTH BY FRIDAY NIGHT. A DEEPENING UPPER LEVEL LOW WILL SLOWLY BEGAN TO DEGRADE THE RIDGE ACROSS THE PLAINS BY FRIDAY NIGHT. AT THE SURFACE....DEVELOPING LOW PRESSURE ALONG THE ROCKIES....COMBINED WITH DECENT THETA E ADVECTION WILL PROVIDE AT LEAST A CHANCE FOR PRECIPITATION ACROSS THE WESTERN ZONES FRIDAY NIGHT INTO SATURDAY. BEST CHANCES FOR PRECIPITATION WILL COME SATURDAY NIGHT INTO SUNDAY...AS THE UPPER LEVEL LOW PUSHES INTO THE REGION. INSTABILITY WITH THIS SYSTEM IS PROBABLY THE BEST IN THE LONG TERM...WITH 4500 TO 5000 J/KG NOSING INTO OUR AREA. STILL 700 MB TEMPERATURES ON THE ORDER OF 10 TO 12 CELSIUS INDICATES AT LEAST SOME CAP LINGERING THROUGH SATURDAY NIGHT. 0 TO 6 KM BULK SHEAR VECTORS ARE ALSO NOT TOO HIGH...WITH ABOUT 20 TO 30 KTS ACROSS THE REGION. EVEN STILL...THINKING THAT SATURDAY IS LIKELY THE BEST CHANCE FOR SEVERE DURING THE PERIOD. ALTHOUGH...MODELS REMAIN A BIT INCONSISTENT ON THIS GIVEN LOW PRESSURE SYSTEM...ESPECIALLY REGARDING STRENGTH AND TRACK. THE ECMWF SOLUTION IS A BIT FURTHER NORTH ACROSS THE DAKOTAS AND REMAINS AN OPEN WAVE...WHILE THE GFS HAS TENDED TO BECOME CLOSED DIRECTLY ACROSS OUR CWA FROM RUN TO RUN. DEFINITELY SOMETHING TO CONTINUE TO MONITOR. LINGERING CHANCES FOR PRECIPITATION WILL CONTINUE THROUGHOUT THE REST OF THE LONG TERM...ON THE BACKSIDE OF THE UPPER LEVEL LOW. REGARDING TEMPERATURES IN THE PERIOD...MADE ONLY A FEW TWEAKS. MAINLY LOWERED HIGH TEMPERATURES A FEW DEGREES ON THURSDAY TO REFLECT CHANGES TO CLOUD COVER AND CHANCES FOR PRECIPITATION. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1225 AM CDT WED MAY 15 2013 REST OF TNGT: VFR WITH SCT-BKN 25K FT CIRRUS. NE WINDS WILL AVERAGE JUST UNDER 10 KTS. SOME MARGINAL LLWS IS POSSIBLE. WED: VFR WITH SCT MID-LVL CLOUDS POSSIBLE FROM THE REMNANTS OF SHWR/TSTM ACTIVITY. ENE WINDS 10-15 KTS. WED NGT THRU 06Z: VFR CIRRUS CIGS. ENE WINDS SETTLE AROUND 5 KTS. CIG CONFIDENCE: HIGH VSBY CONFIDENCE: HIGH WIND CONFIDENCE: HIGH WX CONFIDENCE: HIGH && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...HALBLAUB SHORT TERM...HEINLEIN LONG TERM...SALTZMAN AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1023 PM EDT THU MAY 16 2013 .SYNOPSIS... DRY CONDITIONS WILL PERSIST THROUGH AT LEAST SATURDAY MORNING. CLOUDS WILL DEVELOP OVER THE WEEKEND AS A FRONTAL ZONE SETS UP NEAR OUR VICINITY. SOME AREAS MAY GET A FEW LIGHT SHOWERS LATE SATURDAY INTO SUNDAY...WITH BEST CHANCES IN NORTHEAST PENNSYLVANIA. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... 1015 PM UPDATE... WEAK SECONDARY FRONT CONTINUES TO SINK SOUTH ACROSS THE REGION THIS EVENING WITH UPSTREAM OBSERVATIONS AT ART AND GTB CLEARLY SHOWING A WINDSHIFT TO THE NORTH. IR SATELLITE IMAGERY A FAIRLY RAPID DECREASE IN CLOUDS ALONG THIS FEATURE WITH LOSS OF DAYTIME HEATING AND SKY GRIDS HAVE BEEN ADJUSTED ACCORDINGLY. SOME CONCERN STILL LINGERS FOR PATCHY FROST ACROSS THE CHEMUNG BASIN AFTER 06Z BUT OVERALL CONFIDENCE REMAINS MARGINAL AS TEMPS HAVE BEEN SLOW TO COOL THIS EVENING WITH FRONT STILL TO THE NORTH THIS HR. SINCE WE CANNOT RULE IT OUT HOWEVER...A PATCHY FROST MENTION HAS BEEN MAINTAINED FOR NOW. NO OTHER ADJUSTMENTS NEEDED AT THIS TIME. 715 PM UPDATE... FCST IN GREAT SHAPE THIS EVENING...NO SIGNIFICANT CHANGES NEEDED AT THE PRESENT TIME. VIS SATELLITE SHOTS STILL SHOWING A FAIRLY WELL DEFINED AND NARROW CU FIELD ALONG A SOUTHWARD SAGGING SECONDARY COLD FRONT WHICH NOW STRETCHES FROM NEAR WATERTOWN/FT. DRUM...WEST THROUGH KINGSTON ONTARIO. FEATURE WILL CONTINUE DIVING SOUTH THROUGH THE FCST AREA THIS EVENING BEFORE CLEARING THE CWA SHORTLY AFTER 06Z. ATTENTION THROUGH THE OVERNIGHT WILL REMAIN FOCUSED ON POSSIBLE FROST POTENTIAL ACROSS THE CHEMUNG RVR VLY. WILL CONTINUE TO MONITOR TRENDS HOWEVER LATEST MODEL GUIDANCE CONTINUES TO SUGGEST FAIRLY DRY LOW-LEVEL CONDITIONS WHICH SHOULD KEEP FROST DEVELOPMENT RATHER ISOLATED AT BEST. 3 PM UPDATE... JUST A FEW FAIR WEATHER CUMULUS AT 8-10 KFT AGL THIS AFTERNOON WHICH WILL QUICKLY DISSIPATE. AS EXPECTED...INVERTED-V PROFILE HAS MIXED DOWN FAIRLY GUSTY WINDS ALONG WITH VERY DRY AIR AND THUS A MAXIMIZED DIURNAL RANGE. WIDESPREAD 70S WITH SOME LOCATIONS SUCH AS ELMIRA EVEN TOUCHING 80 DEGREES FOR TEMPERATURES...AND HUMIDITY VALUES AREAWIDE HAVE MANAGED MAINLY 20S PERCENT RANGE. SECONDARY COLD FRONT WILL DIP ACROSS THE AREA TONIGHT...AND WITH SUCH LIMITED MOISTURE...NO PRECIPITATION EXPECTED WHATSOEVER. LOSS OF DIURNAL HEATING WILL ERODE MUCH OF THE CLOUD COVER CURRENTLY BEHIND THE FRONT IN CENTRAL ONTARIO AND QUEBEC. HOWEVER...WRFARW AND RUC SOUNDINGS SHOW THAT BAND OF MOISTURE 4-5 KFT AGL WILL ADVECT IN IMMEDIATELY ALONG THE FRONT ITSELF. SKY GRIDS THUS REFLECT SOME CLOUDS DROPPING ACROSS THE NORTHERN TO CENTRAL PART OF THE AREA OVERNIGHT...BEFORE MIXING OUT IN DRY AIR FRIDAY MORNING. EXPECTING MAINLY 40S FOR LOWS TONIGHT...BUT FAIR AMOUNT OF RADIATIONAL COOLING WILL LEAD THE TYPICAL COLDER DRAINAGE-PRONE SPOTS GETTING INTO THE 30S. PATCHY FROST HAS BEEN ADDED TO A COUPLE SPOTS IN THE WEATHER GRIDS IN CENTRAL SOUTHERN TIER OF NY TO BRADFORD COUNTY PA...BUT NOT EXPECTING ENOUGH TO WARRANT FROST ADVISORY. THE EVENING SHIFT WILL MONITOR THIS CLOSELY IN CASE EXPECTATIONS SHOULD CHANGE. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... 315 PM UPDATE... HIGH PRESSURE IN CHARGE FRIDAY INTO FRIDAY NIGHT WITH DRY WEATHER AND TEMPERATURES RIGHT AROUND CLIMATOLOGY. BAROCLINIC ZONE SETS UP JUST SOUTH AND SOUTHWEST OF OUR VICINITY OVER THE WEEKEND. WHAT HAS BECOME CLEARER IS THAT CLOUDS WILL DEVELOP AND THICKEN COURTESY OF MOISTENING BAROCLINIC LIFT...ESPECIALLY CENTRAL TO SOUTHERN ZONES. HOWEVER...WITH DRY AIR IN THE LOW LEVELS AND FAIRLY WEAK WAVES ALOFT...PRECIPITATION CHANCES ARE MUCH MORE IFFY. ALSO...AS HIGH PRESSURE SITUATES OFFSHORE INTO SUNDAY...STABILIZING COOL ONSHORE SOUTHEAST FLOW WILL DIP TEMPERATURES ESPECIALLY FROM TWIN TIERS SOUTHWARD. EVER SLOW SLIGHT YET VERY ELEVATED INSTABILITY ALSO IS SUGGESTED BY THE SOUNDINGS AT LEAST FOR LATE SATURDAY INTO SATURDAY NIGHT. OVERALL NOT VERY BULLISH ON RAIN CHANCES BUT HAVE TO RESPECT PRESENCE OF BAROCLINIC ZONE AND MOISTURE...WHICH SOMETIMES YIELDS SURPRISES THAT MODELS CAN STRUGGLE WITH. FOR NOW...WENT WITH SLIGHT TO LOW CHANCE POPS MAINLY WESTERN/SOUTHERN ZONES LATE SATURDAY...THEN SPREADING OVER REMAINDER OF THE AREA SATURDAY NIGHT INTO SUNDAY. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... MEDIUM RANGE MODELS ARE IN FAIR AGREEMENT THROUGH THIS PERIOD INDICATING AN UPPER LEVEL RIDGE WILL BUILD OVER THE NORTHEAST INITIALLY AS AN UPPER LEVEL TROF DIGS INTO THE NORTHERN PLAINS. TOWARD THE END OF THE PERIOD THE RIDGE WILL FLATTEN THEN AN UPPER LEVEL TROF DROPPING THROUGH EASTERN CANADA WILL MOVE INTO THE NORTHEAST. AT THE SFC, SUNDAY NIGHT INTO MONDAY, HIGH PRES OFF THE NEW ENGLAND COAST AND A WARM FRONT DRAPED OVER THE MID ATLANTIC WILL PROVIDE A SOMEWHAT MOIST RETURN FLOW BRINGING PRIMARILY A SLIGHT CHC FOR SHOWERS OVER CENTRAL NY AND CHC FOR NE PA. FOR THE REMAINDER OF THE PERIOD WILL CONTINUE TO CARRY CHC POPS FOR SHOWERS AND THUNDERSTORMS, AS SFC LOW PRES MOVING INTO THE WESTERN LAKES WILL BRING A WARM FRONT TO THE VCNTY THROUGH TUESDAY NIGHT WITH THE TRAILING COLD FRONT MOVING THROUGH WED/WED NIGHT. WILL ADVERTISE CHC/SLIGHT CHC POPS ON THURSDAY, POST FRONTAL AS UPPER LEVEL TROF RESIDES OVER REGION. TEMPS THROUGH THE PERIOD WILL RUN 5-10 DEGREES ABOVE NORMAL WITH A RETURN TO MORE SEASONAL TEMPS BY THURSDAY. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... VFR CONDITIONS WILL PREVAIL THROUGH FRIDAY. SOME MINOR INCONVENIENCES TO FLIGHT OPS MAY OCCUR ACROSS THE NORTHERN TERMINALS TONIGHT AS A SECONDARY FRONTAL BOUNDARY DROPS SOUTH WITH AN ASSOCIATED NORTH WIND SHIFT AND SOME LOWER BKN-OVC VFR CIGS. THESE ARE EXPECTED TO ERODE SOME WITH A SOUTHWARD MOVEMENT THROUGH TIME AND LIKELY NOT REACH LOCATIONS FROM KBGM-KELM SOUTH. GUSTY NW-N WINDS NEXT HOUR OR SO WILL DIMINISH TO UNDER 10 KTS AND THEN INCREASE AFTER SUNRISE FRIDAY TO AROUND 8-12 KNOTS. OUTLOOK... FRI NIGHT THROUGH TUESDAY...PRIMARILY VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MDP NEAR TERM...CMG/MDP SHORT TERM...MDP LONG TERM...RRM AVIATION...JAB
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
745 PM EDT THU MAY 16 2013 .SYNOPSIS... DRY CONDITIONS WILL PERSIST THROUGH AT LEAST SATURDAY MORNING. CLOUDS WILL DEVELOP OVER THE WEEKEND AS A FRONTAL ZONE SETS UP NEAR OUR VICINITY. SOME AREAS MAY GET A FEW LIGHT SHOWERS LATE SATURDAY INTO SUNDAY...WITH BEST CHANCES IN NORTHEAST PENNSYLVANIA. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... 715 PM UPDATE... FCST IN GREAT SHAPE THIS EVENING...NO SIGNIFICANT CHANGES NEEDED AT THE PRESENT TIME. VIS SATELLITE SHOTS STILL SHOWING A FAIRLY WELL DEFINED AND NARROW CU FIELD ALONG A SOUTHWARD SAGGING SECONDARY COLD FRONT WHICH NOW STRETCHES FROM NEAR WATERTOWN/FT. DRUM...WEST THROUGH KINGSTON ONTARIO. FEATURE WILL CONTINUE DIVING SOUTH THROUGH THE FCST AREA THIS EVENING BEFORE CLEARING THE CWA SHORTLY AFTER 06Z. ATTENTION THROUGH THE OVERNIGHT WILL REMAIN FOCUSED ON POSSIBLE FROST POTENTIAL ACROSS THE CHEMUNG RVR VLY. WILL CONTINUE TO MONITOR TRENDS HOWEVER LATEST MODEL GUIDANCE CONTINUES TO SUGGEST FAIRLY DRY LOW-LEVEL CONDITIONS WHICH SHOULD KEEP FROST DEVELOPMENT RATHER ISOLATED AT BEST. 3 PM UPDATE... JUST A FEW FAIR WEATHER CUMULUS AT 8-10 KFT AGL THIS AFTERNOON WHICH WILL QUICKLY DISSIPATE. AS EXPECTED...INVERTED-V PROFILE HAS MIXED DOWN FAIRLY GUSTY WINDS ALONG WITH VERY DRY AIR AND THUS A MAXIMIZED DIURNAL RANGE. WIDESPREAD 70S WITH SOME LOCATIONS SUCH AS ELMIRA EVEN TOUCHING 80 DEGREES FOR TEMPERATURES...AND HUMIDITY VALUES AREAWIDE HAVE MANAGED MAINLY 20S PERCENT RANGE. SECONDARY COLD FRONT WILL DIP ACROSS THE AREA TONIGHT...AND WITH SUCH LIMITED MOISTURE...NO PRECIPITATION EXPECTED WHATSOEVER. LOSS OF DIURNAL HEATING WILL ERODE MUCH OF THE CLOUD COVER CURRENTLY BEHIND THE FRONT IN CENTRAL ONTARIO AND QUEBEC. HOWEVER...WRFARW AND RUC SOUNDINGS SHOW THAT BAND OF MOISTURE 4-5 KFT AGL WILL ADVECT IN IMMEDIATELY ALONG THE FRONT ITSELF. SKY GRIDS THUS REFLECT SOME CLOUDS DROPPING ACROSS THE NORTHERN TO CENTRAL PART OF THE AREA OVERNIGHT...BEFORE MIXING OUT IN DRY AIR FRIDAY MORNING. EXPECTING MAINLY 40S FOR LOWS TONIGHT...BUT FAIR AMOUNT OF RADIATIONAL COOLING WILL LEAD THE TYPICAL COLDER DRAINAGE-PRONE SPOTS GETTING INTO THE 30S. PATCHY FROST HAS BEEN ADDED TO A COUPLE SPOTS IN THE WEATHER GRIDS IN CENTRAL SOUTHERN TIER OF NY TO BRADFORD COUNTY PA...BUT NOT EXPECTING ENOUGH TO WARRANT FROST ADVISORY. THE EVENING SHIFT WILL MONITOR THIS CLOSELY IN CASE EXPECTATIONS SHOULD CHANGE. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... 315 PM UPDATE... HIGH PRESSURE IN CHARGE FRIDAY INTO FRIDAY NIGHT WITH DRY WEATHER AND TEMPERATURES RIGHT AROUND CLIMATOLOGY. BAROCLINIC ZONE SETS UP JUST SOUTH AND SOUTHWEST OF OUR VICINITY OVER THE WEEKEND. WHAT HAS BECOME CLEARER IS THAT CLOUDS WILL DEVELOP AND THICKEN COURTESY OF MOISTENING BAROCLINIC LIFT...ESPECIALLY CENTRAL TO SOUTHERN ZONES. HOWEVER...WITH DRY AIR IN THE LOW LEVELS AND FAIRLY WEAK WAVES ALOFT...PRECIPITATION CHANCES ARE MUCH MORE IFFY. ALSO...AS HIGH PRESSURE SITUATES OFFSHORE INTO SUNDAY...STABILIZING COOL ONSHORE SOUTHEAST FLOW WILL DIP TEMPERATURES ESPECIALLY FROM TWIN TIERS SOUTHWARD. EVER SLOW SLIGHT YET VERY ELEVATED INSTABILITY ALSO IS SUGGESTED BY THE SOUNDINGS AT LEAST FOR LATE SATURDAY INTO SATURDAY NIGHT. OVERALL NOT VERY BULLISH ON RAIN CHANCES BUT HAVE TO RESPECT PRESENCE OF BAROCLINIC ZONE AND MOISTURE...WHICH SOMETIMES YIELDS SURPRISES THAT MODELS CAN STRUGGLE WITH. FOR NOW...WENT WITH SLIGHT TO LOW CHANCE POPS MAINLY WESTERN/SOUTHERN ZONES LATE SATURDAY...THEN SPREADING OVER REMAINDER OF THE AREA SATURDAY NIGHT INTO SUNDAY. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... MEDIUM RANGE MODELS ARE IN FAIR AGREEMENT THROUGH THIS PERIOD INDICATING AN UPPER LEVEL RIDGE WILL BUILD OVER THE NORTHEAST INITIALLY AS AN UPPER LEVEL TROF DIGS INTO THE NORTHERN PLAINS. TOWARD THE END OF THE PERIOD THE RIDGE WILL FLATTEN THEN AN UPPER LEVEL TROF DROPPING THROUGH EASTERN CANADA WILL MOVE INTO THE NORTHEAST. AT THE SFC, SUNDAY NIGHT INTO MONDAY, HIGH PRES OFF THE NEW ENGLAND COAST AND A WARM FRONT DRAPED OVER THE MID ATLANTIC WILL PROVIDE A SOMEWHAT MOIST RETURN FLOW BRINGING PRIMARILY A SLIGHT CHC FOR SHOWERS OVER CENTRAL NY AND CHC FOR NE PA. FOR THE REMAINDER OF THE PERIOD WILL CONTINUE TO CARRY CHC POPS FOR SHOWERS AND THUNDERSTORMS, AS SFC LOW PRES MOVING INTO THE WESTERN LAKES WILL BRING A WARM FRONT TO THE VCNTY THROUGH TUESDAY NIGHT WITH THE TRAILING COLD FRONT MOVING THROUGH WED/WED NIGHT. WILL ADVERTISE CHC/SLIGHT CHC POPS ON THURSDAY, POST FRONTAL AS UPPER LEVEL TROF RESIDES OVER REGION. TEMPS THROUGH THE PERIOD WILL RUN 5-10 DEGREES ABOVE NORMAL WITH A RETURN TO MORE SEASONAL TEMPS BY THURSDAY. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... VFR CONDITIONS WILL PREVAIL THROUGH FRIDAY. SOME MINOR INCONVENIENCES TO FLIGHT OPS MAY OCCUR ACROSS THE NORTHERN TERMINALS TONIGHT AS A SECONDARY FRONTAL BOUNDARY DROPS SOUTH WITH AN ASSOCIATED NORTH WIND SHIFT AND SOME LOWER BKN-OVC VFR CIGS. THESE ARE EXPECTED TO ERODE SOME WITH A SOUTHWARD MOVEMENT THROUGH TIME AND LIKELY NOT REACH LOCATIONS FROM KBGM-KELM SOUTH. GUSTY NW-N WINDS NEXT HOUR OR SO WILL DIMINISH TO UNDER 10 KTS AND THEN INCREASE AFTER SUNRISE FRIDAY TO AROUND 8-12 KNOTS. OUTLOOK... FRI NIGHT THROUGH TUESDAY...PRIMARILY VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MDP NEAR TERM...CMG/MDP SHORT TERM...MDP LONG TERM...RRM AVIATION...JAB
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
714 PM EDT THU MAY 16 2013 .SYNOPSIS... DRY CONDITIONS WILL PERSIST THROUGH AT LEAST SATURDAY MORNING. CLOUDS WILL DEVELOP OVER THE WEEKEND AS A FRONTAL ZONE SETS UP NEAR OUR VICINITY. SOME AREAS MAY GET A FEW LIGHT SHOWERS LATE SATURDAY INTO SUNDAY...WITH BEST CHANCES IN NORTHEAST PENNSYLVANIA. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... 715 PM UPDATE... FCST IN GREAT SHAPE THIS EVENING...NO SIGNIFICANT CHANGES NEEDED AT THE PRESENT TIME. VIS SATELLITE SHOTS STILL SHOWING A FAIRLY WELL DEFINED AND NARROW CU FIELD ALONG A SOUTHWARD SAGGING SECONDARY COLD FRONT WHICH NOW STRETCHES FROM NEAR WATERTOWN/FT. DRUM...WEST THROUGH KINGSTON ONTARIO. FEATURE WILL CONTINUE DIVING SOUTH THROUGH THE FCST AREA THIS EVENING BEFORE CLEARING THE CWA SHORTLY AFTER 06Z. ATTENTION THROUGH THE OVERNIGHT WILL REMAIN FOCUSED ON POSSIBLE FROST POTENTIAL ACROSS THE CHEMUNG RVR VLY. WILL CONTINUE TO MONITOR TRENDS HOWEVER LATEST MODEL GUIDANCE CONTINUES TO SUGGEST FAIRLY DRY LOW-LEVEL CONDITIONS WHICH SHOULD KEEP FROST DEVELOPMENT RATHER ISOLATED AT BEST. 3 PM UPDATE... JUST A FEW FAIR WEATHER CUMULUS AT 8-10 KFT AGL THIS AFTERNOON WHICH WILL QUICKLY DISSIPATE. AS EXPECTED...INVERTED-V PROFILE HAS MIXED DOWN FAIRLY GUSTY WINDS ALONG WITH VERY DRY AIR AND THUS A MAXIMIZED DIURNAL RANGE. WIDESPREAD 70S WITH SOME LOCATIONS SUCH AS ELMIRA EVEN TOUCHING 80 DEGREES FOR TEMPERATURES...AND HUMIDITY VALUES AREAWIDE HAVE MANAGED MAINLY 20S PERCENT RANGE. SECONDARY COLD FRONT WILL DIP ACROSS THE AREA TONIGHT...AND WITH SUCH LIMITED MOISTURE...NO PRECIPITATION EXPECTED WHATSOEVER. LOSS OF DIURNAL HEATING WILL ERODE MUCH OF THE CLOUD COVER CURRENTLY BEHIND THE FRONT IN CENTRAL ONTARIO AND QUEBEC. HOWEVER...WRFARW AND RUC SOUNDINGS SHOW THAT BAND OF MOISTURE 4-5 KFT AGL WILL ADVECT IN IMMEDIATELY ALONG THE FRONT ITSELF. SKY GRIDS THUS REFLECT SOME CLOUDS DROPPING ACROSS THE NORTHERN TO CENTRAL PART OF THE AREA OVERNIGHT...BEFORE MIXING OUT IN DRY AIR FRIDAY MORNING. EXPECTING MAINLY 40S FOR LOWS TONIGHT...BUT FAIR AMOUNT OF RADIATIONAL COOLING WILL LEAD THE TYPICAL COLDER DRAINAGE-PRONE SPOTS GETTING INTO THE 30S. PATCHY FROST HAS BEEN ADDED TO A COUPLE SPOTS IN THE WEATHER GRIDS IN CENTRAL SOUTHERN TIER OF NY TO BRADFORD COUNTY PA...BUT NOT EXPECTING ENOUGH TO WARRANT FROST ADVISORY. THE EVENING SHIFT WILL MONITOR THIS CLOSELY IN CASE EXPECTATIONS SHOULD CHANGE. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... 315 PM UPDATE... HIGH PRESSURE IN CHARGE FRIDAY INTO FRIDAY NIGHT WITH DRY WEATHER AND TEMPERATURES RIGHT AROUND CLIMATOLOGY. BAROCLINIC ZONE SETS UP JUST SOUTH AND SOUTHWEST OF OUR VICINITY OVER THE WEEKEND. WHAT HAS BECOME CLEARER IS THAT CLOUDS WILL DEVELOP AND THICKEN COURTESY OF MOISTENING BAROCLINIC LIFT...ESPECIALLY CENTRAL TO SOUTHERN ZONES. HOWEVER...WITH DRY AIR IN THE LOW LEVELS AND FAIRLY WEAK WAVES ALOFT...PRECIPITATION CHANCES ARE MUCH MORE IFFY. ALSO...AS HIGH PRESSURE SITUATES OFFSHORE INTO SUNDAY...STABILIZING COOL ONSHORE SOUTHEAST FLOW WILL DIP TEMPERATURES ESPECIALLY FROM TWIN TIERS SOUTHWARD. EVER SLOW SLIGHT YET VERY ELEVATED INSTABILITY ALSO IS SUGGESTED BY THE SOUNDINGS AT LEAST FOR LATE SATURDAY INTO SATURDAY NIGHT. OVERALL NOT VERY BULLISH ON RAIN CHANCES BUT HAVE TO RESPECT PRESENCE OF BAROCLINIC ZONE AND MOISTURE...WHICH SOMETIMES YIELDS SURPRISES THAT MODELS CAN STRUGGLE WITH. FOR NOW...WENT WITH SLIGHT TO LOW CHANCE POPS MAINLY WESTERN/SOUTHERN ZONES LATE SATURDAY...THEN SPREADING OVER REMAINDER OF THE AREA SATURDAY NIGHT INTO SUNDAY. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... MEDIUM RANGE MODELS ARE IN FAIR AGREEMENT THROUGH THIS PERIOD INDICATING AN UPPER LEVEL RIDGE WILL BUILD OVER THE NORTHEAST INITIALLY AS AN UPPER LEVEL TROF DIGS INTO THE NORTHERN PLAINS. TOWARD THE END OF THE PERIOD THE RIDGE WILL FLATTEN THEN AN UPPER LEVEL TROF DROPPING THROUGH EASTERN CANADA WILL MOVE INTO THE NORTHEAST. AT THE SFC, SUNDAY NIGHT INTO MONDAY, HIGH PRES OFF THE NEW ENGLAND COAST AND A WARM FRONT DRAPED OVER THE MID ATLANTIC WILL PROVIDE A SOMEWHAT MOIST RETURN FLOW BRINGING PRIMARILY A SLIGHT CHC FOR SHOWERS OVER CENTRAL NY AND CHC FOR NE PA. FOR THE REMAINDER OF THE PERIOD WILL CONTINUE TO CARRY CHC POPS FOR SHOWERS AND THUNDERSTORMS, AS SFC LOW PRES MOVING INTO THE WESTERN LAKES WILL BRING A WARM FRONT TO THE VCNTY THROUGH TUESDAY NIGHT WITH THE TRAILING COLD FRONT MOVING THROUGH WED/WED NIGHT. WILL ADVERTISE CHC/SLIGHT CHC POPS ON THURSDAY, POST FRONTAL AS UPPER LEVEL TROF RESIDES OVER REGION. TEMPS THROUGH THE PERIOD WILL RUN 5-10 DEGREES ABOVE NORMAL WITH A RETURN TO MORE SEASONAL TEMPS BY THURSDAY. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... VFR CONDITIONS WILL CONTINUE THROUGH THIS TAF PERIOD. SCATTERED MID LEVEL CLOUDS WILL CLEAR BY EARLY EVENING BEFORE A SECONDARY TROF DROPS THROUGH OVERNIGHT. THIS FEATURE WILL PRODUCE SCT/BKN CLOUDS AROUND 4K FT. ON FRIDAY, JUST SCATTERED CU WILL PERSIST. NORTHWEST WINDS AT 10-12 KNOTS GUSTING TO 25 KNOTS THEN DECREASING TO 5 KNOTS THIS EVENING. NORTHWEST WINDS AROUND 10 KNOTS ON FRIDAY. OUTLOOK... FRI NIGHT THROUGH TUESDAY...PRIMARILY VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MDP NEAR TERM...CMG/MDP SHORT TERM...MDP LONG TERM...RRM AVIATION...RRM
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
938 PM CDT THU MAY 16 2013 .UPDATE... ISSUED AT 937 PM CDT THU MAY 16 2013 SFC HIGH PRESSURE OVER ONTARIO AND A DEVELOPING LOW OVER CO/WY CONTINUES TO BRING NORTHEASTERLY WINDS THAT WILL SLOWLY SHIFT AROUND TO THE EAST LATER TONIGHT. STILL THINK THAT OUR LIGHT RAIN ALONG THE HIGHWAY 2 CORRIDOR WILL SLOWLY DIMINISH AS CONVECTION RAMPS UP FURTHER SOUTH. HOWEVER...PRECIP HAS MOVED A BIT FURTHER EAST THAN EARLIER EXPECTATIONS SO ADJUSTED POPS/WX ACCORDINGLY. KEPT LIKELIES GOING FOR THE REST OF THE EVENING AND THEN STARTED TO DROP THEM DOWN LATER TONIGHT. UPDATE ISSUED AT 646 PM CDT THU MAY 16 2013 BAND OF LIGHT RAIN CONTINUES FROM NEAR DEVILS LAKE TO THE CENTRAL RED RIVER VALLEY INTO NORTHWESTERN MINNESOTA...WITH SPRINKLES ELSEWHERE. THE NAM AND RAP ARE IN PRETTY GOOD AGREEMENT ON THIS ACTIVITY DIMINISHING LATER THIS EVENING AS THE COMPLEX OVER SD/MN GETS GOING AND ROBS MOISTURE. KEPT HIGH POPS IN THE NORTH THIS EVENING BEFORE TRANSITIONING TO BETTER PERCENTAGES IN THE SOUTH LATER ON TONIGHT. LOWERED TEMPS A BIT IN THE NORTHWEST AS READINGS HAVE ALREADY DROPPED INTO THE LOWER 50S AND THERE COULD BE SOME BREAKS IN THE CLOUDS LATER TONIGHT TO ALLOW IT TO GET DOWN INTO THE UPPER 40S. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 120 PM CDT THU MAY 16 2013 THE MAIN CHALLENGE WILL BE UPCOMING PROLONGED WET PATTERN TONIGHT INTO THE MIDDLE OF NEXT WEEK. MODELS ARE IN GOOD OVERALL AGREEMENT INITIALLY...WITH SOME DIFFERENCES BY NEXT WEEK. THE NAM/GFS ARE A GOOD COMPROMISE IN THE NEAR TERM. FOR TONIGHT...THERE WILL BE AN AREA OF SHOWERS MOVING FROM WEST TO EAST ACROSS THE AREA. THIS BAND OF SHOWERS IS BEING AIDED BY STRONG MID LEVEL OMEGA AND UPPER LEVEL DIVERGENCE...AS PWATS INCREASE TO AROUND 1 INCH. THERE SHOULD BE A BAND OF STRONGER CONVECTION SOUTH OF THE AREA OVERNIGHT...THAT SHOULD ROB THE DEEPER MOISTURE FROM OUR AREA. WE WILL INCREASE POPS THIS EVENING IN THE WEST INTO THE CENTRAL RED RIVER VALLEY WITH STRONGER ECHOES MOVING INTO THE AREA. FOR FRIDAY...WE SHOULD GET A BREAK IN THE LARGER SCALE SHOWERS WITH EASTERLY FLOW NEAR THE SFC INCREASING. WE WILL MAINTAIN A LOW CHANCE FOR SHOWERS THOUGH WITH PLENTY OF CLOUDS AND POSSIBLY A SUBTLE SHORTWAVE MOVING THROUGH. FOR FRIDAY NIGHT...A LLJ WILL DEVELOP IN SD AND MOVE INTO THE SOUTH OVERNIGHT EXPECT AN AREA OF SHOWERS AND THUNDERSTORMS TO MOVE INTO THE AREA...WITH THE BEST CHANCE FOR THUNDER IN THE SOUTH. THERE WILL BE SOME ELEVATED INSTABILITY WITH 850MB CAPE AROUND 1000 J/KG...SO A STRONG TO LOCALLY SEVERE STORM IS POSSIBLE. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 310 PM CDT THU MAY 16 2013 FOR SATURDAY THROUGH SUNDAY...A VERY ACTIVE WEATHER PATTERN IS EXPECTED. SHOWERS AND STORMS SHOULD BE ONGOING AT LEAST IN THE SOUTH SATURDAY MORNING. BY SATURDAY AFTERNOON AND EVENING...DEEP MOISTURE AND STRONG INSTABILITY SHOULD DEVELOP OVER SE ND...NEAR THE EDGE OF A STRONG CAPPING INVERSION. MLCAPES ARE PROGGED OVER 4000 J/KG INTO NC SD...AND AROUND 3000 J/KG IN SE ND. EXPECT STORMS TO DEVELOP QUICKLY IN SD ONCE THE CAP BREAKS...AND MOVE NORTH AND EAST INTO THE AREA SATURDAY NIGHT AND SUNDAY. SOME STORMS COULD BE SEVERE SATURDAY NIGHT INTO SUNDAY...BUT LOCALLY HEAVY RAIN IS POSSIBLE WITH PWATS RISING TO AROUND 1.5 INCHES OR EVEN A BIT HIGHER. WE HAVE ISSUED AN ESF FOR SOME LOCALIZED FLOODING POSSIBLE IF TRAINING ECHOES OCCUR WITH A PARALLEL UPPER BOUNDARY. SAME SCENARIO IN PLACE FOR EXTENDED...AFTER A WEEKEND OF RAIN AND THUNDERSTORMS...UPPER LOW LIKELY TO BE LOCATED OVER AN AREA ANYWHERE FROM SOUTHEAST NORTH DAKOTA TO IOWA. MOISTURE WILL STILL BE TRANSPORTED CYCLONICALLY AROUND THIS STACKED SYSTEM CONTINUING SHOWERS WITH THE POSSIBILITY OF SOME THUNDER. ORIENTATION OF BOUNDARY AND ASSOCIATED CONVECTIVE PARAMETERS MAKE MONDAY THE MORE LIKELY TIME FOR THUNDER ACTIVITY...LESS SO ON TUESDAY AND BY WEDNESDAY PRECIPITATION SHOULD BE MORE SHOWERY OR EVEN JUST SOME STRATIFORM RAIN. GOING POP FREE FINALLY BY THURSDAY AS AN OMEGA BLOCK DEVELOPS WITH NORTHERN PLAINS UNDER THE RIDGE PART OF THE BLOCK. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING) ISSUED AT 646 PM CDT THU MAY 16 2013 VFR CEILINGS AND LIGHT RAIN OVER THE NORTHERN TAF SITES WILL CONTINUE THROUGH THE EVENING HOURS. WILL HAVE TO WATCH FOR SOME MVFR CLOUDS COMING IN LATER TONIGHT AND INTO TOMORROW BUT FOR NOW KEPT MVFR MENTION JUST AT KDVL. RAIN HAS BEEN PLAYING HAVOC ON THE WINDS WITH KFAR BEING QUITE BREEZY FROM THE NORTH. THINK THAT THINGS SHOULD CALM DOWN AND GO BACK TO THE GRADIENT EASTERLIES LATER ON THIS EVENING. && .HYDROLOGY... ISSUED AT 310 PM CDT THU MAY 16 2013 THE NORTHERN PORTION OF THE RED RIVER CONTINUES TO SEE RIVER LEVELS UNDERGO RECESSION AT DRAYTON AND PEMBINA. THIS IS THE LAST REMNANT OF THE SNOWMELT WATER SURGE CONTINUING TO MOVE NORTHWARD INTO CANADA. A PROLONGED PERIOD OF UNSETTLED WEATHER IS EXPECTED TO BEGIN THIS EVENING AND CONTINUE THROUGH TUESDAY. CUMULATIVE RAINFALL TOTALS OF 2 TO 4 INCHES ACROSS THE RED RIVER BASIN...WITH LOCALLY HIGHER AMOUNTS...WILL BE POSSIBLE BY TUESDAY MORNING. LOCALIZED FLASH FLOODING IS A POSSIBILITY OVER THE WEEKEND DUE TO TRAINING THUNDERSTORMS. IN ADDITION...DESPITE SOME RAINFALL INFILTRATION DUE TO PATCHY DRY TOPSOIL...ENOUGH RUNOFF MAY OCCUR TO CAUSE SOME SMALLER TRIBUTARIES TO RISE BACK ABOVE FLOOD STAGE NEXT WEEK. AS A RESULT...A HYDROLOGIC OUTLOOK HAS BEEN ISSUED TO HIGHLIGHT THE SITUATION. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...JR SHORT TERM...DK LONG TERM...WJB/DK AVIATION...JR HYDROLOGY...BRAMER
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
646 PM CDT THU MAY 16 2013 .UPDATE... ISSUED AT 646 PM CDT THU MAY 16 2013 BAND OF LIGHT RAIN CONTINUES FROM NEAR DEVILS LAKE TO THE CENTRAL RED RIVER VALLEY INTO NORTHWESTERN MINNESOTA...WITH SPRINKLES ELSEWHERE. THE NAM AND RAP ARE IN PRETTY GOOD AGREEMENT ON THIS ACTIVITY DIMINISHING LATER THIS EVENING AS THE COMPLEX OVER SD/MN GETS GOING AND ROBS MOISTURE. KEPT HIGH POPS IN THE NORTH THIS EVENING BEFORE TRANSITIONING TO BETTER PERCENTAGES IN THE SOUTH LATER ON TONIGHT. LOWERED TEMPS A BIT IN THE NORTHWEST AS READINGS HAVE ALREADY DROPPED INTO THE LOWER 50S AND THERE COULD BE SOME BREAKS IN THE CLOUDS LATER TONIGHT TO ALLOW IT TO GET DOWN INTO THE UPPER 40S. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 120 PM CDT THU MAY 16 2013 THE MAIN CHALLENGE WILL BE UPCOMING PROLONGED WET PATTERN TONIGHT INTO THE MIDDLE OF NEXT WEEK. MODELS ARE IN GOOD OVERALL AGREEMENT INITIALLY...WITH SOME DIFFERENCES BY NEXT WEEK. THE NAM/GFS ARE A GOOD COMPROMISE IN THE NEAR TERM. FOR TONIGHT...THERE WILL BE AN AREA OF SHOWERS MOVING FROM WEST TO EAST ACROSS THE AREA. THIS BAND OF SHOWERS IS BEING AIDED BY STRONG MID LEVEL OMEGA AND UPPER LEVEL DIVERGENCE...AS PWATS INCREASE TO AROUND 1 INCH. THERE SHOULD BE A BAND OF STRONGER CONVECTION SOUTH OF THE AREA OVERNIGHT...THAT SHOULD ROB THE DEEPER MOISTURE FROM OUR AREA. WE WILL INCREASE POPS THIS EVENING IN THE WEST INTO THE CENTRAL RED RIVER VALLEY WITH STRONGER ECHOES MOVING INTO THE AREA. FOR FRIDAY...WE SHOULD GET A BREAK IN THE LARGER SCALE SHOWERS WITH EASTERLY FLOW NEAR THE SFC INCREASING. WE WILL MAINTAIN A LOW CHANCE FOR SHOWERS THOUGH WITH PLENTY OF CLOUDS AND POSSIBLY A SUBTLE SHORTWAVE MOVING THROUGH. FOR FRIDAY NIGHT...A LLJ WILL DEVELOP IN SD AND MOVE INTO THE SOUTH OVERNIGHT EXPECT AN AREA OF SHOWERS AND THUNDERSTORMS TO MOVE INTO THE AREA...WITH THE BEST CHANCE FOR THUNDER IN THE SOUTH. THERE WILL BE SOME ELEVATED INSTABILITY WITH 850MB CAPE AROUND 1000 J/KG...SO A STRONG TO LOCALLY SEVERE STORM IS POSSIBLE. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 310 PM CDT THU MAY 16 2013 FOR SATURDAY THROUGH SUNDAY...A VERY ACTIVE WEATHER PATTERN IS EXPECTED. SHOWERS AND STORMS SHOULD BE ONGOING AT LEAST IN THE SOUTH SATURDAY MORNING. BY SATURDAY AFTERNOON AND EVENING...DEEP MOISTURE AND STRONG INSTABILITY SHOULD DEVELOP OVER SE ND...NEAR THE EDGE OF A STRONG CAPPING INVERSION. MLCAPES ARE PROGGED OVER 4000 J/KG INTO NC SD...AND AROUND 3000 J/KG IN SE ND. EXPECT STORMS TO DEVELOP QUICKLY IN SD ONCE THE CAP BREAKS...AND MOVE NORTH AND EAST INTO THE AREA SATURDAY NIGHT AND SUNDAY. SOME STORMS COULD BE SEVERE SATURDAY NIGHT INTO SUNDAY...BUT LOCALLY HEAVY RAIN IS POSSIBLE WITH PWATS RISING TO AROUND 1.5 INCHES OR EVEN A BIT HIGHER. WE HAVE ISSUED AN ESF FOR SOME LOCALIZED FLOODING POSSIBLE IF TRAINING ECHOES OCCUR WITH A PARALLEL UPPER BOUNDARY. SAME SCENARIO IN PLACE FOR EXTENDED...AFTER A WEEKEND OF RAIN AND THUNDERSTORMS...UPPER LOW LIKELY TO BE LOCATED OVER AN AREA ANYWHERE FROM SOUTHEAST NORTH DAKOTA TO IOWA. MOISTURE WILL STILL BE TRANSPORTED CYCLONICALLY AROUND THIS STACKED SYSTEM CONTINUING SHOWERS WITH THE POSSIBILITY OF SOME THUNDER. ORIENTATION OF BOUNDARY AND ASSOCIATED CONVECTIVE PARAMETERS MAKE MONDAY THE MORE LIKELY TIME FOR THUNDER ACTIVITY...LESS SO ON TUESDAY AND BY WEDNESDAY PRECIPITATION SHOULD BE MORE SHOWERY OR EVEN JUST SOME STRATIFORM RAIN. GOING POP FREE FINALLY BY THURSDAY AS AN OMEGA BLOCK DEVELOPS WITH NORTHERN PLAINS UNDER THE RIDGE PART OF THE BLOCK. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING) ISSUED AT 646 PM CDT THU MAY 16 2013 VFR CEILINGS AND LIGHT RAIN OVER THE NORTHERN TAF SITES WILL CONTINUE THROUGH THE EVENING HOURS. WILL HAVE TO WATCH FOR SOME MVFR CLOUDS COMING IN LATER TONIGHT AND INTO TOMORROW BUT FOR NOW KEPT MVFR MENTION JUST AT KDVL. RAIN HAS BEEN PLAYING HAVOC ON THE WINDS WITH KFAR BEING QUITE BREEZY FROM THE NORTH. THINK THAT THINGS SHOULD CALM DOWN AND GO BACK TO THE GRADIENT EASTERLIES LATER ON THIS EVENING. && .HYDROLOGY... ISSUED AT 310 PM CDT THU MAY 16 2013 THE NORTHERN PORTION OF THE RED RIVER CONTINUES TO SEE RIVER LEVELS UNDERGO RECESSION AT DRAYTON AND PEMBINA. THIS IS THE LAST REMNANT OF THE SNOWMELT WATER SURGE CONTINUING TO MOVE NORTHWARD INTO CANADA. A PROLONGED PERIOD OF UNSETTLED WEATHER IS EXPECTED TO BEGIN THIS EVENING AND CONTINUE THROUGH TUESDAY. CUMULATIVE RAINFALL TOTALS OF 2 TO 4 INCHES ACROSS THE RED RIVER BASIN...WITH LOCALLY HIGHER AMOUNTS...WILL BE POSSIBLE BY TUESDAY MORNING. LOCALIZED FLASH FLOODING IS A POSSIBILITY OVER THE WEEKEND DUE TO TRAINING THUNDERSTORMS. IN ADDITION...DESPITE SOME RAINFALL INFILTRATION DUE TO PATCHY DRY TOPSOIL...ENOUGH RUNOFF MAY OCCUR TO CAUSE SOME SMALLER TRIBUTARIES TO RISE BACK ABOVE FLOOD STAGE NEXT WEEK. AS A RESULT...A HYDROLOGIC OUTLOOK HAS BEEN ISSUED TO HIGHLIGHT THE SITUATION. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...JR SHORT TERM...DK LONG TERM...WJB/DK AVIATION...JR HYDROLOGY...BRAMER
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
650 PM EDT WED MAY 15 2013 .SYNOPSIS... A COLD FRONT JUST SOUTH OF THE LAKESHORE WILL PUSH INTO CENTRAL OHIO TONIGHT AND THEN STALL. THE FRONT WILL LIFT NORTH AS A WARM FRONT THIS WEEKEND. && .NEAR TERM /THROUGH THURSDAY/... COLD FRONT CURRENTLY SOUTH OF THE LAKESHORE. SHOWERS HAVE ENDED ACROSS THE SOUTHERN TIER OF COUNTIES. SO HAVE REMOVED THE PRECIP CHANCES FOR THE REMAINDER OF THE EVENING. DID HOWEVER RE-INTRODUCE A SLIGHT CHANCE FOR A SHOWER/TS FROM FINDLAY TO MILLERSBURG. HRRR AND RAP WANT TO PAINT SOME QPF TONIGHT. IT HAS A REASONABLE PICTURE FOR THE CONDITIONS RIGHT NOW...AND WITH BOUNDARY IN THE VICINITY AND A LITTLE BIT OF ENERGY UPSTREAM...DID NOT WANT A COMPLETELY DRY FORECAST. WILL WATCH FOR THIS TONIGHT. FOR TEMPS WENT UPPER 40S TO THE MID 50S. HOWEVER...BELIEVE THE MODELS OVERDOING THE CLOUDS TONIGHT...IF THAT IS THE CASE TEMPS WILL BE A LITTLE LOWER. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... MODELS CONTINUE TO STALL THE FRONT WELL SOUTH OF THE AREA. GFS A LITTLE SLOWER TODAY MOVING THE FRONT NORTH. EXCEPT FOR THE EXTREME SW PORTION OF THE FORECAST AREA REMOVED MENTION OF POPS FOR FRIDAY AND FRIDAY NIGHT. MODELS STILL IN CONFLICT FOR SATURDAY. ECMWF KEEPS FRONT SOUTH OF THE AREA ON SATURDAY WHILE GFS CONTINUES TO HAVE THE FRONT ACROSS THE AREA. FOR NOW SEE NO REASON TO START FLIP FLOPPING FORECASTS THIS FAR OUT WHEN THINGS ARE STILL IN DOUBT. SO FOR NOW KEPT CHANCE POPS GOING FOR SATURDAY. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... THE RIDGE IS STILL PROGGED TO BUILD ACROSS THE AREA THIS WEEKEND THROUGH EARLY NEXT WEEK. THE CHANCES OF SHOWERS/STORMS SHOULD DIMINISH UNDER THE BUILDING RIDGE. CANNOT TOTALLY RULE OUT OUT A SHOWER OR THUNDERSTORM GIVEN THE OLD FRONTAL BOUNDARY OR SOME OUTFLOW/MESO BOUNDARY... INCREASING HEAT ETC...BUT FOR THE MOST PART SUNDAY AND MONDAY SHOULD BE WARM AND MOSTLY RAIN FREE. CUT BACK ON THE 12 HOUR POP SUNDAY/MONDAY MOSTLY TO 15 TO 25 PERCENT. THIS WILL BE "SLIGHT CHANCE" IN MOST FORECASTS WHICH DOES NOT SHOW UP IN MOST OF OUR TEXT FORECASTS (AFTER THE FIRST DAY). BY THE MIDDLE OF NEXT WEEK THE NEXT FRONT FROM THE WEST SHOULD WORK INTO THE AREA. IT WILL LIKELY NOT BE IN A HURRY TO MOVE EAST AS A TROUGH ALOFT IS PROGGED TO BE DEEPENING IN THE MIDDLE OF THE COUNTRY. WILL HAVE A HIGHER CHANCE OF SHOWERS AND THUNDERSTORMS BY TUESDAY AND WEDNESDAY. WILL BEGIN TO CUT BACK ON TEMPERATURES BY NEXT WEDNESDAY GIVEN THE INCREASE IN CLOUDS AND SHOWERS. FORECAST HIGHS WILL BE ABOVE GUIDANCE GIVEN THE BIG RIDGE AND THE TIME OF YEAR. HIGHS 75 TO 80 SUNDAY...AROUND 80 OR IN THE LOWER 80S MONDAY AND TUESDAY...THEN 70S WEDNESDAY. LOWS GENERALLY MID 50S TO THE LOWER 60S. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... THE WEAK COLD FRONT HAS SLIPPED ACROSS THE LAKE ERIE LAKESHORE AND SHOULD MAKE SLOW PROGRESS SOUTHEAST DURING THE AFTERNOON/EVENING. COUNTING ON NO NEW SHOWERS TO DEVELOP WITH THE FRONT AS THE EARLIER BATCH OF SHOWERS/STORMS IS NOW SOUTHEAST OF THE TAF SITES. GUSTY WEST WINDS WILL DIMINISH QUICKLY THIS EVENING. PATCHES OF MID AND HIGH CLOUDS WILL SPREAD IN FROM THE WEST TONIGHT AND THURSDAY BUT VFR CONDITIONS WILL CONTINUE. .OUTLOOK... NON-VFR POSSIBLE IN SHOWERS OR THUNDERSTORMS SATURDAY AND SUNDAY. && .MARINE... A FAIRLY TIGHT PRESSURE GRADIENT IS IN PLACE ACROSS LAKE ERIE THIS AFTERNOON EXTENDING FROM LOW PRESSURE APPROACHING JAMES BAY. THIS TROUGH WILL SHIFT EAST OF THE LAKE THIS EVENING...PUSHING A COLD FRONT SOUTH ACROSS THE LAKE WITH DECREASING WINDS AND WAVES. THE SMALL CRAFT ADVISORY WEST OF AVON WILL BE ALLOWED TO EXPIRE AT 4 PM AND THE ENDING TIME OF 10 PM STILL LOOKS ON TRACK FOR THE EASTERN PORTION OF THE LAKE. HIGH PRESSURE WILL SLOWLY BUILD EAST ACROSS THE LAKE FROM THURSDAY THROUGH THE WEEKEND. TEMPERATURES WILL BE ABOVE NORMAL THROUGH THIS TIME WITH STABLE CONDITIONS ON THE LAKE. WINDS WILL GENERALLY BE LESS THAN 15 KNOTS WITH WAVES LESS THAN 2 FEET. LOW PRESSURE WILL SLOWLY APPROACH THE REGION FROM THE WEST EARLY NEXT WEEK BRINGING INCREASING CHANCES OF SHOWERS AND THUNDERSTORMS. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LEZ146>149. && $$ SYNOPSIS...DJB NEAR TERM...DJB/OUDEMAN SHORT TERM...DJB LONG TERM...KOSARIK AVIATION...KOSARIK MARINE...KEC
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
411 AM EDT WED MAY 15 2013 .SYNOPSIS... A WARM AIR MASS WILL REMAIN OVER THE REGION THROUGH THE REST OF THE WEEK. LIGHT SOUTHWEST WINDS WILL SUPPLY HIGHER HUMIDITY VALUES EACH DAY THIS PERIOD. A MID LEVEL DISTURBANCE WILL ARRIVE OVER THE REGION ON THURSDAY AND WILL REMAIN INTO FRIDAY. AN UNSETTLED PATTERN WILL CONTINUE ACROSS THE REGION THIS WEEKEND THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 410 AM EDT...WILL PUSH NRN NC MTN WINDS UP SLIGHTLY GIVEN LATEST RUC PROFILES AND OBSERVATIONS FROM BOONE TO WEST JEFFERSON. THIS WILL KEEP GUSTS JUST BELOW ADVISORY CRITERIA ALONG THE HIGHER RIDGE TOPS...WITH LESSER GUSTS IN THE LOWER MTN VALLEYS. OTHERWISE...A FLAT RIDGE WILL PERSIST OVER THE AREA TODAY AS A CLOSED LOW PRES SYSTEM MOVES SLOWLY E ACROSS THE SOUTHERN PLAINS. STOUT WESTERLY 850 MB FLOW OVER THE RIDGE AXIS WILL IMPACT THE HIGHEST ELEVATIONS OF THE NC MTNS THIS MORNING...BUT WITH WINDS GENERALLY NOT MIXING DOWN TO THE MID SLOPES OR LOWER VALLEYS IN THIS WARM ADVECTION REGIME. THE WESTERLY FLOW WILL PRODUCE DOWNSLOPE WARMING EAST OF THE MTNS TODAY...WITH A LEE TROUGH LIKELY STRENGTHENING. A FEW SREF MEMBERS AS WELL AS THE OPERATIONAL GFS HAVE ISOLATED SHOWERS LATE TODAY IN THE LEE TROUGH AXIS. MODEL PROFILES INDICATE FAIRLY DECENT SFC BASED CAPE VALUES AROUND 1000 J/KG. HOWEVER...LOW LEVEL CONVERGENCE IN THE LEE TROUGH SHOULD BE TOO WEAK TO PROVIDE MUCH TRIGGERING GIVEN THE RELATIVELY HIGH LFC HEIGHTS. MAX TEMPS WILL SURGE TO 7 TO 10 DEGREES ABOVE NORMAL IN MOST LOCATIONS THIS AFTN. THE H5 LOW WILL MEANDER INTO THE MID MS RIVER VALLEY TONIGHT...WITH ALL ATTENDANT SHORTWAVE ENERGY STAYING W OF THE FORECAST AREA THROUGH THE PERIOD. EXPECT MAINLY AN INCREASE IN HIGH CLOUDS FROM THE W OVERNIGHT...WITH MIN TEMPERATURES 1 TO 2 CATEGORIES ABOVE NORMAL. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... AS OF 225 AM WEDNESDAY...BROAD MID LEVEL RIDGING WILL REMAIN OVER THE FORECAST AREA BY SUNRISE THURSDAY. DURING THE AFTERNOON AND EVENING...THE H5 TROUGH WILL RIPPLE ACROSS THE SOUTHERN MISSISSIPPI RIVER VALLEY...RESULTING IN FALLING HEIGHTS ACROSS THE SOUTHERN APPALACHIANS. AT THE SFC...A WEST TO EAST FRONT WILL BECOMING STATIONARY ACROSS THE MID APPALACHIANS AND MID ATLANTIC STATES...WITH HIGH PRESSURE ACROSS THE SOUTHEAST. FORECAST SOUNDINGS INDICATE FAIRLY MILD TEMPERATURES BELOW H5 WITH DEEP WEST WINDS. A CONSENSUS OF MOS GUIDANCE SUPPORTS HIGHS WITHIN THE MTN VALLEYS IN THE LOW 80S WITH MID TO UPPER 80S EAST...DEWPOINTS IN THE LOW TO MID 50S. FORECAST SOUNDINGS ALSO INDICATES CIN VALUES BETWEEN 50-100 J/KG EAST OF THE MTNS. I WILL FORECAST CHC POPS ACROSS THE MTNS FOR SHRA/TSRA...FAVORING THE TN LINE FOR THE GREATEST COVERAGE. EAST OF THE MTNS...INHIBITION SHOULD KEEP DEEP CONVECTION LIMITED TO ISO COVERAGE. CONVECTION IS FORECAST TO SLOWLY ASHE OUT DURING THE EVENING HOURS. CLOUD COVER AND MILE LLVL THICKNESSES WILL FAVOR MIN TEMPERATURES AROUND 3 TO 5 DEGREES ABOVE NORMAL. FRIDAY...THE H5 TROF OR CLOSED LOW IS EXPECTED TO SLIDE OVER THE FORECAST AREA DURING THE AFTERNOON. SHORT RANGE MODELS SHOW VERY LITTLE CHANGE IN THE SFC FEATURES FROM THURSDAY. HOWEVER...INCREASING MOISTURE AND GRADUALLY RISING DEWPOINTS SHOULD PROVIDE SLIGHT INCREASE IN CONDITIONAL INSTABILITY WITH SHALLOW CIN LAYER. I WILL FORECAST CHC POPS ACROSS THE NC AND MTN ZONES...SCHC ELSEWHERE. HIGH TEMPERATURES WILL LIKELY RANGE VERY CLOSE TO THURSDAY VALUES. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AS OF 240 AM WEDNESDAY...MEDIUM RANGE GUIDANCE INDICATES THAT UNSETTLED ZONAL FLOW WILL REMAIN OVER THE CWA DURING THE WEEKEND...SHALLOW RIDGING EXPECTED EARLY NEXT WEEK. THE GFS APPEARS VERY CHAOTIC WITH A FEW PASSAGES OF MCS FEATURES ACROSS KY/TN/NC. THE ECMWF APPEARS LESS ACTIVE WITH MCS/S...BUT DOES INDICATE A RIPE ENVIRONMENT FOR DIURNAL CONVECTION. I WILL USE A BLEND OF BOTH SOLUTIONS...FORECASTING CHC POPS PEAKING DURING THE HEAT OF THE AFTERNOON...ONLY FADING TO SCHC AT NIGHT...COVERAGE GREATEST OVER THE MTNS. TEMPERATURES WILL FEATURE LITTLE CHANGE FROM DAY TO DAY...REMAINING 3 TO 5 DEGREES ABOVE NORMAL. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL CONTINUE THROUGH THE TAF PERIOD. WESTERLY FLOW OVER THE MTNS WILL HELP TO ESTABLISH A LEE TROUGH E OF THE BLUE RIDGE TODAY...WITH WINDS ADJUSTING TO SW AT THE FOOTHILLS TAF SITES AS WELL AS KCLT. LOW END GUSTS OF 17 TO 19 KT ARE EXPECTED WITH PEAK MIXING THIS AFTN. MAINLY FEW TO SCT MID AND HIGH CLOUDS ARE EXPECTED...BUT HIGH BASED CONVECTIVE CUMULUS MAY DEVELOP IN THE LEE TROUGH CONVERGENCE AXIS THIS AFTERNOON...ESPECIALLY FROM KGSP TO KCLT. EXPECT LIGHT SW FLOW TONIGHT...WITH HIGH CLOUDS INCREASING FROM THE W. OUTLOOK...VFR CONDITIONS ARE GENERALLY EXPECTED THROUGH THE REST OF THE WEEK. HOWEVER...SCATTERED AFTN AND EVENING THUNDERSTORMS WILL BE POSSIBLE FROM THURSDAY THROUGH THE WEEKEND. CONFIDENCE TABLE... 08-14Z 14-20Z 20-02Z 02-08Z KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100% KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100% KAVL HIGH 100% HIGH 100% HIGH 100% HIGH 100% KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100% KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100% KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...NED NEAR TERM...HG SHORT TERM...NED LONG TERM...NED AVIATION...HG
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1244 PM CDT WED MAY 15 2013 .UPDATE... 18Z AVIATION DISCUSSION UPDATED BELOW. CURRENT RADAR IMAGERY SHOWS ISOLATED SHOWERS EXTENDING FROM EAST CENTRAL SOUTH DAKOTA THROUGH SOUTHWEST NORTH DAKOTA. WHILE LITTLE IN THE WAY OF ADDITIONAL ACCUMULATION TODAY...THE HRRR MODEL HAS PICKED UP ON THIS VERY WELL AND DOES INDICATE THAT ISOLATED SHOWERS OR THUNDERSTORMS WILL LINGER ACROSS THE NORTHERN/EASTERN CWA THIS AFTERNOON. THEREFORE...DID ADD A 20 POP FOR ISOLATED SHOWERS AND THUNDERSTORMS. THE ONLY OTHER MINOR CHANGE TO THE FORECAST WAS TO KNOCK DOWN TEMPERATURES A FEW DEGREES UNDER THE THICKEST CLOUD COVER. WHILE THE CLOUDS ARE EXPECTED TO BREAK APART THIS AFTERNOON...ITS GOING TO TAKE AWHILE FOR IT TO HAPPEN ACROSS THE CENTRAL CWA...AND THEREFORE LIMIT SOME OF THE DAYTIME HEATING. && .PREVIOUS DISCUSSION... .SHORT TERM...TODAY THROUGH FRIDAY PRECIPITATION CHANCES THROUGHOUT THE PERIOD WILL BE THE MAIN FORECAST CHALLENGE. SHOWERS AND THUNDERSTORMS ARE CURRENTLY MOVING ACROSS THE CWA THIS MORNING. RIGHT ENTRANCE REGION OF AN UPPER LEVEL JET ALONG WITH A WEAK SHORT WAVE TROUGH WILL LIKELY CONTINUE TO PRODUCE THESE LIGHT SHOWERS THROUGH THE MID MORNING HOURS BEFORE DIMINISHING. THE LOWER LEVELS ARE RATHER DRY SO WOULD NOT EXPECT A GREAT DEAL OF MOISTURE REACHING THE GROUND. THIS AFTERNOON AND A BETTER PORTION OF TONIGHT WILL BE DRY UNTIL THE NEXT SYSTEM MOVES ACROSS THE REGION LATE TONIGHT THROUGH THURSDAY. THIS STORM SYSTEM APPEARS TO SPLIT IN TWO WITH THE NORTHERN PORTION TRACKING ACROSS NORTH DAKOTA AND THE SOUTHERN PORTION MOVING ALONG AND SOUTH OF I-90. THURSDAY NIGHT LOOKS LIKE THE BEST TIME PERIOD FOR THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS...ESPECIALLY FOR THE EASTERN CWA. ADDITIONAL SHORT WAVE ACTIVITY WILL COMBINE WITH A 35 TO 40 KNOT LLJ TO RESULT IN CONVECTIVE DEVELOPMENT. SEVERE THUNDERSTORMS DO NOT APPEAR LIKELY...NEITHER DOES LOCALLY HEAVY RAINFALL. ASIDE FROM LINGERING CONVECTION DURING THE MORNING HOURS...A BETTER PORTION OF FRIDAY LOOKS DRY. MID LEVEL TEMPERATURES WILL WARM THROUGH THE DAY WITH H7 TEMPS REACHING THE UPPER SINGLE DIGITS. THESE WARM TEMPS SHOULD CAP CONVECTION UNTIL AFTER 00Z SATURDAY OR JUST BEYOND THE SHORT TERM PORTION OF THE FORECAST. .LONG TERM...FRIDAY NIGHT THROUGH TUESDAY AN UPPER LEVEL RIDGE WILL EXIT THE REGION FRIDAY NIGHT AND SATURDAY AHEAD OF AN APPROACHING TROUGH. SHORTWAVE ENERGY ASSOCIATED WITH THE TROUGH WILL THEN AFFECT THE NORTHERN PLAINS THROUGH THE END OF THE PERIOD. THE MODELS ARE IN DECENT AGREEMENT WITH THE SURFACE PATTERN THROUGH THE DAY MONDAY...THEN BEGIN TO DIVERGE SOME AS THE ECMWF BRINGS HIGH PRESSURE OVER THE AREA WHILE THE GFS KEEPS THE LOW IN THE VICINITY LONGER. THERE IS SOME DECENT INSTABILITY THAT SHOWS UP ACROSS THE WEST FRIDAY NIGHT...AND EVEN BETTER INSTABILITY ACROSS THE CENTRAL AND EAST SATURDAY NIGHT. EXPECT THERE COULD BE SOME STRONG TO SEVERE THUNDERSTORMS SOMEWHERE IN THE AREA BOTH EVENINGS. CANNOT REALLY DISCERN ANY TIME PERIOD WHEN IT WILL BE COMPLETELY DRY...SO WILL STICK CLOSE TO ALLBLEND POPS...WHICH ARE GENERALLY IN THE SCHC TO HIGH CHC CATEGORY THROUGHOUT THE PERIOD. SATURDAY WILL BE THE WARMEST DAY OF THE PERIOD WITH HIGH TEMPERATURES GENERALLY IN THE 70S. WILL THEN SEE A COOLING TREND THROUGH THE REST OF THE PERIOD UNDER MOSTLY CLOUDY SKIES AND WITH CHANCES OF PRECIPITATION. HIGHS WILL BE IN THE UPPER 60S TO LOWER 70S ON SUNDAY...THEN MAINLY IN THE 60S MONDAY AND TUESDAY. && .AVIATION... 18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS VFR CONDITIONS ARE EXPECTED AT ALL TERMINALS THROUGH THURSDAY MORNING. ANOTHER SHORT WAVE TROUGH MOVING IN FROM THE WEST WILL SPREAD MID LEVEL CLOUDS INTO THE REGION LATER TONIGHT AND EAST THROUGH THURSDAY. ALONG WITH THE CLOUDS WILL COME SOME SCATTERED SHOWERS/THUNDERSTORMS MAINLY ON THURSDAY. WILL HAVE TO WATCH FOR THEM TO POSSIBLY AFFECT THE TERMINALS. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...MOHR/SERR SHORT TERM...SD LONG TERM...PARKIN AVIATION...MOHR WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1213 PM CDT WED MAY 15 2013 .UPDATE... ISSUED AT 1114 AM CDT WED MAY 15 2013 EXTENDED THE POPS FURTHER IN TOWN AND BOOSTED COVERAGE EARLIER THIS MORNING PRIMARILY ALONG THE HIGHWAY 14 CORRIDOR. SHORT WAVE ENERGY CONTINUES TO MOVE EASTWARD ALONG WITH A FAIR AMOUNT OF MID LEVEL BASED FRONTOGENESIS IN THAT AREA. LOOKING UPSTREAM...IT APPEARS THINGS MAY COOPERATE AND MOVE OUT OF OUR AREA FOR A BULK OF THE AFTERNOON HOURS...ALLOWING OUR NORTHERN ZONES TO WARM UP. THAT SAID...DUE TO EXTENSIVE CLOUD COVER THIS MORNING...DID LOWER SOME HIGHS A CATEGORY OR SO IN EAST CENTRAL SD AND ACROSS THE NORTHERN PORTIONS OF SOUTHWEST MN. ELSEWHERE...THE HIGH TEMPERATURES STILL LOOK PRETTY GOOD...ONLY ADJUSTED A FEW OF THEM A DEGREE OR TWO. OTHERWISE...SURFACE HIGH PRESSURE AXIS WILL REMAIN VERY CLOSE TO OUR NORTHERN ZONES THIS AFTERNOON. THIS MAKES THE WIND DIRECTION RATHER TRICKY FOR THE ON GOING SPOT BURN FORECASTS FOR THOSE AREAS. IN ADDITION...THERE IS SOME INDICATION WITH THE SHORT RANGE HIGH RES MODELS THAT THE WIND DIRECTION WILL SHIFT TO THE NORTH ALONG AND NORTH OF I 90 AS THE AFTERNOON PROGRESSES LIKELY DUE TO THE RAINFALL. HOWEVER AT THIS TIME...THERE IS NO INDICATION OF THAT HAPPENING OTHER THAN A LIGHT NORTH WIND AT MADISON. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 428 AM CDT WED MAY 15 2013 LINGERING MID LEVEL BOUNDARY AND SOME WEAKLY UNSTABLE 700-500 HPA LAPSE RATES CREATING SOME ISSUES WITH THE FORECAST EARLY THIS MORNING. WAVE TOPPING DEVELOPING RIDGE ALOFT AND NUDGING UP AGAINST NORTHWEST SOUTH DAKOTA ACTING TO INDUCE SOME CROSS FRONTAL FLOW... AND WEAK REGION OF HIGH BASED LIFT FROM NORTHWEST TO SOUTHEAST ACROSS THE STATE. MID LEVEL FRONTOGENETIC FORCING REMAINS FAIRLY STRONG MAINLY ALONG AND NORTH OF I90 THROUGH THE DAY... WEAKENING SOME BY AFTERNOON AS WAVE MOVES PAST. VERY DRY LOWER ATMOSPHERE IS CERTAINLY IMPACTING THE POTENTIAL EASTWARD SPREAD AND OVERALL COVERAGE OF WETTING RAINFALL. THE HRRR KEEP SLIPPING AWAY ON DEVELOPING PRECIP...PUSHING IT BACK AT LEAST AN HOUR OR TWO WITH SUCCESSIVE RUN DESPITE THE INCREASING PRESENCE ON RADAR OVER THE LAST HOUR OR TWO. HIGH RES MODELS SEEM TO HAVE THE RIGHT IDEA...AND SUPPORT FROM LARGER SCALE DYNAMICS MENTIONED ABOVE. INDICATIONS ON VARIOUS FORECAST SOUNDING FROM 100 TO 300 J/K ELEVATED INSTABILITY...SO WOULD NOT BE SURPRISED TO GET A FEW RUMBLES OF HIGH BASED THUNDER...EVEN WITH THE OVERALL PROBABILITY/ COVERAGE OF PRECIPITATION LIKELY LACKING...AND AT THIS POINT NOT WARRANTING MUCH MORE THAN A LOWER SCATTERED MENTION. SOME CONCERN THAT LINGERING CLOUDS AND ANY EVAPORATIVE EFFECTS WOULD HAVE AN IMPACT ON TEMPERATURES TODAY...BUT SHOULD START TO GET AT LEAST A DECENT AMOUNT OF SUNSHINE AFTER MAIN WAVE SHEARS BY TO THE NORTH...AND LINGERING DIV Q ACROSS THE SOUTH WEAKENS AS WELL. MIXING CENTERS AROUND THE MID TO UPPER 70S...AND DID NUDGE THIS JUST A BIT HIGHER FOR THE FAR WEST. TONIGHT LOOKS TO BE QUIETEST PERIOD OF THE FORECAST...WITH WEAK MID TO UPPER LEVEL RIDGING OVER THE AREA TONIGHT AHEAD OF NEXT WAVE. NAM AND GEM ACTUALLY A BIT FASTER IN BRINGING PRECIP CHANCE BACK INTO OUR SOUTHWEST LATE TONIGHT...HOWEVER BEST FORCING WITH WARM ADVECTION AND ADVANCING WAVE APPEARS TO REMAIN FOCUSED JUST WEST OF OUR AREA THROUGH 12Z AND WILL LEAVE TONIGHT DRY AS A RESULT. LIGHT WINDS AND RELATIVELY DRY AIR MASS WILL ALLOW FOR FAIR AMOUNT OF RADIATIONAL COOLING...AND LOWS IN THE LOWER 50S LOOK REASONABLE FOR MOST AREAS. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 428 AM CDT WED MAY 15 2013 MESSY PATTERN THROUGHOUT THE LONG TERM PERIOD OF THIS FORECAST...WITH DIFFICULTY PINPOINTING ANY PERIOD WHICH COULD BE SIGNIFICANTLY DRIER THAN ANOTHER. PERIOD STARTS WITH WARM FRONT AND ASSOCIATED WAVE MOVING ACROSS THE FORECAST AREA THURSDAY/THURSDAY NIGHT. NAM/GEM/ECMWF QUITE BULLISH IN PRODUCING FAIR AMOUNT OF PRECIP WITH THIS SYSTEM...WHILE THE GFS IS MUCH DRIER THOUGH STILL INDICATIVE OF SOME PRECIP CHANCE. 15/00Z NAM SEEMS TO BE SLIGHT OUTLIER IN SPEED WITH WHICH IS TRACKS THE WAVE AND ASSOCIATED PRECIP TO THE NORTHEAST ON THURSDAY...AND HAVE GENERALLY FOLLOWED SLOWER IDEA FOR NOW...KEEPING OUR NORTHEAST COUNTIES DRY UNTIL THURSDAY EVENING. PERSISTENT WARM ADVECTION WILL THEN LEAD TO INCREASING PRECIP CHANCE THROUGH THE OVERNIGHT HOURS THURSDAY NIGHT. TEMPERATURES SHOULD BE SEASONABLE WITH HIGHS THURSDAY IN THE MID TO UPPER 70S. INCREASING MOISTURE/CLOUD COVER WILL HOLD TEMPERATURES UP IN THE UPPER 50S THURSDAY NIGHT. MUCH OF FRIDAY/FRIDAY NIGHT COULD AGAIN BE BETWEEN PERIODS OF MORE WIDESPREAD/ORGANIZED PRECIPITATION...THOUGH EASTERN AREAS COULD SEE A FEW THUNDERSTORMS LINGER INTO THE MORNING...WHILE THE WEST HAS A CHANCE OF DEVELOPMENT FRIDAY NIGHT AS RETURN FLOW OF MOISTURE MOVES INTO CENTRAL SOUTH DAKOTA. WITH WARM FRONT EXPECTED TO BE NORTH OF THE AREA BY FRIDAY AFTERNOON...AND GENERAL LACK OF PRECIP ALONG WITH BREEZY SOUTH WINDS...SHOULD SEE DECENT MIXING TO HELP WARM TEMPS INTO THE MID 80S ACROSS THE WEST. DESPITE WARMER TEMPS AND POTENTIAL FOR SOME GUSTY WINDS...DO NOT EXPECT SIGNIFICANT FIRE DANGER FRIDAY AS WE SHOULD HAVE MUCH HIGHER BOUNDARY LAYER MOISTURE WITH EVEN MIXED OUT DEW POINTS HOLDING IN THE UPPER 50S TO AROUND 60. THAT MOISTURE ALONG WITH WEAK LOW LEVEL JET WILL HOLD OVERNIGHT LOWS IN THE LOWER TO MID 60S FOR FRIDAY NIGHT. SATURDAY INTO SATURDAY NIGHT CONTINUES TO LOOK LIKE MOST FAVORED PERIOD FOR ORGANIZED PRECIPITATION ACROSS THE REGION...AS BROAD WESTERN CONUS TROUGH BEGINS TO SHIFT EASTWARD INTO THE PLAINS. PRECIP SHOULD INITIALLY BE FOCUSED NEAR BOUNDARY ACROSS CENTRAL SOUTH DAKOTA BY SATURDAY AFTERNOON...WITH THUNDERSTORMS THEN EXPANDING EASTWARD ACROSS OUR FORECAST AREA SATURDAY NIGHT. THIS PERIOD CONTINUES TO BE GREATEST THREAT FOR SEVERE WEATHER FOR OUR FORECAST AREA...WITH STEEP MID LEVEL LAPSE RATES AND DEEP FORCING AHEAD OF TROUGH BRINGING POTENTIAL FOR HAIL/WIND. AS IS TYPICAL IN CONVECTIVE SEASON...MODELS NOT SHOWING A GREAT DEAL OF AGREEMENT IN TIMING/LOCATION OF BOUNDARIES FROM THIS POINT FORWARD. HOWEVER...THEY HAVE TRENDED TOWARD A FAVORED SOLUTION IN CLOSING OFF THE UPPER LOW SOMEWHERE IN THE CENTRAL/NORTHERN PLAINS BY SUNDAY NIGHT/MONDAY...WITH THE LOW THEN PERSISTING ACROSS THIS REGION THROUGH MUCH OF EARLY NEXT WEEK. THIS LEADS TO POTENTIAL FOR AT LEAST SCATTERED PRECIPITATION SUNDAY THROUGH TUESDAY...AND HAVE NOT STRAYED FAR FROM CONSENSUS GRIDS WHICH HOLD ONTO CHANCE RANGE POPS FOR THE LONGER RANGE. TEMPERATURES SHOWING LESS AGREEMENT LATE IN THE PERIOD...WITH LATEST ECMWF WRAPPING MUCH COLDER AIR AROUND THE BACK SIDE OF THE UPPER LOW BY MONDAY AND ESPECIALLY TUESDAY. FOR NOW WILL STICK WITH SOMEWHAT MORE MILD GFS/CONSENSUS SOLUTION WHICH... ALTHOUGH COOLER THAN THE MILD TEMPERATURES EXPECTED THROUGH THE WEEKEND...WILL KEEP HIGHS IN THE 60S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1212 PM CDT WED MAY 15 2013 ISOLATED THUNDERTORMS WILL CONTINUE TO MOVE EASTWARD GENERALLY ALONG AND EAST OF THE I 29 CORRIDOR FOR THE NEXT FEW HOURS INTO MID AFTERNOON. MENTIONED A THUNDERSTORM IN THE VICINITY OF THE KFSD AIRPORT THROUGH 2 PM...THEN THE ACTIVITY SHOULD PUSH OFF TO THE EAST. THE SHOWERS AND ISOLATED THUNDERSTORMS ARE VERY HIGH BASED...COMING OUT OF ACCAS CLOUDS. HOWEVER MODERATE TO STRONG WINDS ARE NOT EXPECTED UNDER ANY OF THESE SHOWERS. OTHERWISE THE AREA WILL BE VFR THROUGH THURSDAY MORNING. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ UPDATE...MJF SHORT TERM...CHAPMAN/JH LONG TERM...JH AVIATION...MJF
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1115 AM CDT WED MAY 15 2013 .UPDATE... ISSUED AT 1114 AM CDT WED MAY 15 2013 EXTENDED THE POPS FURTHER IN TOWN AND BOOSTED COVERAGE EARLIER THIS MORNING PRIMARILY ALONG THE HIGHWAY 14 CORRIDOR. SHORT WAVE ENERGY CONTINUES TO MOVE EASTWARD ALONG WITH A FAIR AMOUNT OF MID LEVEL BASED FRONTOGENESIS IN THAT AREA. LOOKING UPSTREAM...IT APPEARS THINGS MAY COOPERATE AND MOVE OUT OF OUR AREA FOR A BULK OF THE AFTERNOON HOURS...ALLOWING OUR NORTHERN ZONES TO WARM UP. THAT SAID...DUE TO EXTENSIVE CLOUD COVER THIS MORNING...DID LOWER SOME HIGHS A CATEGORY OR SO IN EAST CENTRAL SD AND ACROSS THE NORTHERN PORTIONS OF SOUTHWEST MN. ELSEWHERE...THE HIGH TEMPERATURES STILL LOOK PRETTY GOOD...ONLY ADJUSTED A FEW OF THEM A DEGREE OR TWO. OTHERWISE...SURFACE HIGH PRESSURE AXIS WILL REMAIN VERY CLOSE TO OUR NORTHERN ZONES THIS AFTERNOON. THIS MAKES THE WIND DIRECTION RATHER TRICKY FOR THE ON GOING SPOT BURN FORECASTS FOR THOSE AREAS. IN ADDITION...THERE IS SOME INDICATION WITH THE SHORT RANGE HIGH RES MODELS THAT THE WIND DIRECTION WILL SHIFT TO THE NORTH ALONG AND NORTH OF I 90 AS THE AFTERNOON PROGRESSES LIKELY DUE TO THE RAINFALL. HOWEVER AT THIS TIME...THERE IS NO INDICATION OF THAT HAPPENING OTHER THAN A LIGHT NORTH WIND AT MADISON. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 428 AM CDT WED MAY 15 2013 LINGERING MID LEVEL BOUNDARY AND SOME WEAKLY UNSTABLE 700-500 HPA LAPSE RATES CREATING SOME ISSUES WITH THE FORECAST EARLY THIS MORNING. WAVE TOPPING DEVELOPING RIDGE ALOFT AND NUDGING UP AGAINST NORTHWEST SOUTH DAKOTA ACTING TO INDUCE SOME CROSS FRONTAL FLOW... AND WEAK REGION OF HIGH BASED LIFT FROM NORTHWEST TO SOUTHEAST ACROSS THE STATE. MID LEVEL FRONTOGENETIC FORCING REMAINS FAIRLY STRONG MAINLY ALONG AND NORTH OF I90 THROUGH THE DAY... WEAKENING SOME BY AFTERNOON AS WAVE MOVES PAST. VERY DRY LOWER ATMOSPHERE IS CERTAINLY IMPACTING THE POTENTIAL EASTWARD SPREAD AND OVERALL COVERAGE OF WETTING RAINFALL. THE HRRR KEEP SLIPPING AWAY ON DEVELOPING PRECIP...PUSHING IT BACK AT LEAST AN HOUR OR TWO WITH SUCCESSIVE RUN DESPITE THE INCREASING PRESENCE ON RADAR OVER THE LAST HOUR OR TWO. HIGH RES MODELS SEEM TO HAVE THE RIGHT IDEA...AND SUPPORT FROM LARGER SCALE DYNAMICS MENTIONED ABOVE. INDICATIONS ON VARIOUS FORECAST SOUNDING FROM 100 TO 300 J/K ELEVATED INSTABILITY...SO WOULD NOT BE SURPRISED TO GET A FEW RUMBLES OF HIGH BASED THUNDER...EVEN WITH THE OVERALL PROBABILITY/ COVERAGE OF PRECIPITATION LIKELY LACKING...AND AT THIS POINT NOT WARRANTING MUCH MORE THAN A LOWER SCATTERED MENTION. SOME CONCERN THAT LINGERING CLOUDS AND ANY EVAPORATIVE EFFECTS WOULD HAVE AN IMPACT ON TEMPERATURES TODAY...BUT SHOULD START TO GET AT LEAST A DECENT AMOUNT OF SUNSHINE AFTER MAIN WAVE SHEARS BY TO THE NORTH...AND LINGERING DIV Q ACROSS THE SOUTH WEAKENS AS WELL. MIXING CENTERS AROUND THE MID TO UPPER 70S...AND DID NUDGE THIS JUST A BIT HIGHER FOR THE FAR WEST. TONIGHT LOOKS TO BE QUIETEST PERIOD OF THE FORECAST...WITH WEAK MID TO UPPER LEVEL RIDGING OVER THE AREA TONIGHT AHEAD OF NEXT WAVE. NAM AND GEM ACTUALLY A BIT FASTER IN BRINGING PRECIP CHANCE BACK INTO OUR SOUTHWEST LATE TONIGHT...HOWEVER BEST FORCING WITH WARM ADVECTION AND ADVANCING WAVE APPEARS TO REMAIN FOCUSED JUST WEST OF OUR AREA THROUGH 12Z AND WILL LEAVE TONIGHT DRY AS A RESULT. LIGHT WINDS AND RELATIVELY DRY AIR MASS WILL ALLOW FOR FAIR AMOUNT OF RADIATIONAL COOLING...AND LOWS IN THE LOWER 50S LOOK REASONABLE FOR MOST AREAS. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 428 AM CDT WED MAY 15 2013 MESSY PATTERN THROUGHOUT THE LONG TERM PERIOD OF THIS FORECAST...WITH DIFFICULTY PINPOINTING ANY PERIOD WHICH COULD BE SIGNIFICANTLY DRIER THAN ANOTHER. PERIOD STARTS WITH WARM FRONT AND ASSOCIATED WAVE MOVING ACROSS THE FORECAST AREA THURSDAY/THURSDAY NIGHT. NAM/GEM/ECMWF QUITE BULLISH IN PRODUCING FAIR AMOUNT OF PRECIP WITH THIS SYSTEM...WHILE THE GFS IS MUCH DRIER THOUGH STILL INDICATIVE OF SOME PRECIP CHANCE. 15/00Z NAM SEEMS TO BE SLIGHT OUTLIER IN SPEED WITH WHICH IS TRACKS THE WAVE AND ASSOCIATED PRECIP TO THE NORTHEAST ON THURSDAY...AND HAVE GENERALLY FOLLOWED SLOWER IDEA FOR NOW...KEEPING OUR NORTHEAST COUNTIES DRY UNTIL THURSDAY EVENING. PERSISTENT WARM ADVECTION WILL THEN LEAD TO INCREASING PRECIP CHANCE THROUGH THE OVERNIGHT HOURS THURSDAY NIGHT. TEMPERATURES SHOULD BE SEASONABLE WITH HIGHS THURSDAY IN THE MID TO UPPER 70S. INCREASING MOISTURE/CLOUD COVER WILL HOLD TEMPERATURES UP IN THE UPPER 50S THURSDAY NIGHT. MUCH OF FRIDAY/FRIDAY NIGHT COULD AGAIN BE BETWEEN PERIODS OF MORE WIDESPREAD/ORGANIZED PRECIPITATION...THOUGH EASTERN AREAS COULD SEE A FEW THUNDERSTORMS LINGER INTO THE MORNING...WHILE THE WEST HAS A CHANCE OF DEVELOPMENT FRIDAY NIGHT AS RETURN FLOW OF MOISTURE MOVES INTO CENTRAL SOUTH DAKOTA. WITH WARM FRONT EXPECTED TO BE NORTH OF THE AREA BY FRIDAY AFTERNOON...AND GENERAL LACK OF PRECIP ALONG WITH BREEZY SOUTH WINDS...SHOULD SEE DECENT MIXING TO HELP WARM TEMPS INTO THE MID 80S ACROSS THE WEST. DESPITE WARMER TEMPS AND POTENTIAL FOR SOME GUSTY WINDS...DO NOT EXPECT SIGNIFICANT FIRE DANGER FRIDAY AS WE SHOULD HAVE MUCH HIGHER BOUNDARY LAYER MOISTURE WITH EVEN MIXED OUT DEW POINTS HOLDING IN THE UPPER 50S TO AROUND 60. THAT MOISTURE ALONG WITH WEAK LOW LEVEL JET WILL HOLD OVERNIGHT LOWS IN THE LOWER TO MID 60S FOR FRIDAY NIGHT. SATURDAY INTO SATURDAY NIGHT CONTINUES TO LOOK LIKE MOST FAVORED PERIOD FOR ORGANIZED PRECIPITATION ACROSS THE REGION...AS BROAD WESTERN CONUS TROUGH BEGINS TO SHIFT EASTWARD INTO THE PLAINS. PRECIP SHOULD INITIALLY BE FOCUSED NEAR BOUNDARY ACROSS CENTRAL SOUTH DAKOTA BY SATURDAY AFTERNOON...WITH THUNDERSTORMS THEN EXPANDING EASTWARD ACROSS OUR FORECAST AREA SATURDAY NIGHT. THIS PERIOD CONTINUES TO BE GREATEST THREAT FOR SEVERE WEATHER FOR OUR FORECAST AREA...WITH STEEP MID LEVEL LAPSE RATES AND DEEP FORCING AHEAD OF TROUGH BRINGING POTENTIAL FOR HAIL/WIND. AS IS TYPICAL IN CONVECTIVE SEASON...MODELS NOT SHOWING A GREAT DEAL OF AGREEMENT IN TIMING/LOCATION OF BOUNDARIES FROM THIS POINT FORWARD. HOWEVER...THEY HAVE TRENDED TOWARD A FAVORED SOLUTION IN CLOSING OFF THE UPPER LOW SOMEWHERE IN THE CENTRAL/NORTHERN PLAINS BY SUNDAY NIGHT/MONDAY...WITH THE LOW THEN PERSISTING ACROSS THIS REGION THROUGH MUCH OF EARLY NEXT WEEK. THIS LEADS TO POTENTIAL FOR AT LEAST SCATTERED PRECIPITATION SUNDAY THROUGH TUESDAY...AND HAVE NOT STRAYED FAR FROM CONSENSUS GRIDS WHICH HOLD ONTO CHANCE RANGE POPS FOR THE LONGER RANGE. TEMPERATURES SHOWING LESS AGREEMENT LATE IN THE PERIOD...WITH LATEST ECMWF WRAPPING MUCH COLDER AIR AROUND THE BACK SIDE OF THE UPPER LOW BY MONDAY AND ESPECIALLY TUESDAY. FOR NOW WILL STICK WITH SOMEWHAT MORE MILD GFS/CONSENSUS SOLUTION WHICH... ALTHOUGH COOLER THAN THE MILD TEMPERATURES EXPECTED THROUGH THE WEEKEND...WILL KEEP HIGHS IN THE 60S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 521 AM CDT WED MAY 15 2013 ELEVATED INSTABILITY AND A DISTURBANCE MOVING ACROSS FAR NORTHERN SOUTH DAKOTA THIS MORNING WILL CONTINUE TO PRODUCE ISOLATED TO SCATTERED SHOWERS AND A FEW THUNDERSTORMS ACROSS THE AREA. OTHER THAN THE IMMEDIATE SHORT TERM AROUND KHON...NOT LIKELY TO HAVE A HIGH ENOUGH PROBABILITY OF THUNDER TO WARRANT MENTION IN THE TAFS. DESPITE PRECIPITATION...VERY HIGH BASED NATURE WILL MEAN THAT CONDITIONS SHOULD REMAIN VFR. THE PRECIPITATION SHOULD MOVE OUT OF THE IMMEDIATE AREA BY 18Z...AND DRY CONDITIONS ARE EXPECTED THROUGH 12Z THURSDAY. HOWEVER...SCATTERED THUNDERSTORMS SHOULD BE POISED SOUTHWEST OF THE KHON AREA TOWARD 12Z MOVING FROM ORIGINS IN WESTERN NEBRASKA AND SOUTHWEST SOUTH DAKOTA. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ UPDATE...MJF SHORT TERM...CHAPMAN/JH LONG TERM...JH AVIATION...CHAPMAN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1113 AM CDT WED MAY 15 2013 .UPDATE... CURRENT RADAR IMAGERY SHOWS ISOLATED SHOWERS EXTENDING FROM EAST CENTRAL SOUTH DAKOTA THROUGH SOUTHWEST NORTH DAKOTA. WHILE LITTLE IN THE WAY OF ADDITIONAL ACCUMULATION TODAY...THE HRRR MODEL HAS PICKED UP ON THIS VERY WELL AND DOES INDICATE THAT ISOLATED SHOWERS OR THUNDERSTORMS WILL LINGER ACROSS THE NORTHERN/EASTERN CWA THIS AFTERNOON. THEREFORE...DID ADD A 20 POP FOR ISOLATED SHOWERS AND THUNDERSTORMS. THE ONLY OTHER MINOR CHANGE TO THE FORECAST WAS TO KNOCK DOWN TEMPERATURES A FEW DEGREES UNDER THE THICKEST CLOUD COVER. WHILE THE CLOUDS ARE EXPECTED TO BREAK APART THIS AFTERNOON...ITS GOING TO TAKE AWHILE FOR IT TO HAPPEN ACROSS THE CENTRAL CWA...AND THEREFORE LIMIT SOME OF THE DAYTIME HEATING. && .PREVIOUS DISCUSSION... .SHORT TERM...TODAY THROUGH FRIDAY PRECIPITATION CHANCES THROUGHOUT THE PERIOD WILL BE THE MAIN FORECAST CHALLENGE. SHOWERS AND THUNDERSTORMS ARE CURRENTLY MOVING ACROSS THE CWA THIS MORNING. RIGHT ENTRANCE REGION OF AN UPPER LEVEL JET ALONG WITH A WEAK SHORT WAVE TROUGH WILL LIKELY CONTINUE TO PRODUCE THESE LIGHT SHOWERS THROUGH THE MID MORNING HOURS BEFORE DIMINISHING. THE LOWER LEVELS ARE RATHER DRY SO WOULD NOT EXPECT A GREAT DEAL OF MOISTURE REACHING THE GROUND. THIS AFTERNOON AND A BETTER PORTION OF TONIGHT WILL BE DRY UNTIL THE NEXT SYSTEM MOVES ACROSS THE REGION LATE TONIGHT THROUGH THURSDAY. THIS STORM SYSTEM APPEARS TO SPLIT IN TWO WITH THE NORTHERN PORTION TRACKING ACROSS NORTH DAKOTA AND THE SOUTHERN PORTION MOVING ALONG AND SOUTH OF I-90. THURSDAY NIGHT LOOKS LIKE THE BEST TIME PERIOD FOR THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS...ESPECIALLY FOR THE EASTERN CWA. ADDITIONAL SHORT WAVE ACTIVITY WILL COMBINE WITH A 35 TO 40 KNOT LLJ TO RESULT IN CONVECTIVE DEVELOPMENT. SEVERE THUNDERSTORMS DO NOT APPEAR LIKELY...NEITHER DOES LOCALLY HEAVY RAINFALL. ASIDE FROM LINGERING CONVECTION DURING THE MORNING HOURS...A BETTER PORTION OF FRIDAY LOOKS DRY. MID LEVEL TEMPERATURES WILL WARM THROUGH THE DAY WITH H7 TEMPS REACHING THE UPPER SINGLE DIGITS. THESE WARM TEMPS SHOULD CAP CONVECTION UNTIL AFTER 00Z SATURDAY OR JUST BEYOND THE SHORT TERM PORTION OF THE FORECAST. .LONG TERM...FRIDAY NIGHT THROUGH TUESDAY AN UPPER LEVEL RIDGE WILL EXIT THE REGION FRIDAY NIGHT AND SATURDAY AHEAD OF AN APPROACHING TROUGH. SHORTWAVE ENERGY ASSOCIATED WITH THE TROUGH WILL THEN AFFECT THE NORTHERN PLAINS THROUGH THE END OF THE PERIOD. THE MODELS ARE IN DECENT AGREEMENT WITH THE SURFACE PATTERN THROUGH THE DAY MONDAY...THEN BEGIN TO DIVERGE SOME AS THE ECMWF BRINGS HIGH PRESSURE OVER THE AREA WHILE THE GFS KEEPS THE LOW IN THE VICINITY LONGER. THERE IS SOME DECENT INSTABILITY THAT SHOWS UP ACROSS THE WEST FRIDAY NIGHT...AND EVEN BETTER INSTABILITY ACROSS THE CENTRAL AND EAST SATURDAY NIGHT. EXPECT THERE COULD BE SOME STRONG TO SEVERE THUNDERSTORMS SOMEWHERE IN THE AREA BOTH EVENINGS. CANNOT REALLY DISCERN ANY TIME PERIOD WHEN IT WILL BE COMPLETELY DRY...SO WILL STICK CLOSE TO ALLBLEND POPS...WHICH ARE GENERALLY IN THE SCHC TO HIGH CHC CATEGORY THROUGHOUT THE PERIOD. SATURDAY WILL BE THE WARMEST DAY OF THE PERIOD WITH HIGH TEMPERATURES GENERALLY IN THE 70S. WILL THEN SEE A COOLING TREND THROUGH THE REST OF THE PERIOD UNDER MOSTLY CLOUDY SKIES AND WITH CHANCES OF PRECIPITATION. HIGHS WILL BE IN THE UPPER 60S TO LOWER 70S ON SUNDAY...THEN MAINLY IN THE 60S MONDAY AND TUESDAY. && .AVIATION... 12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS AN AREA OF SHOWERS AND WEAK THUNDERSTORMS WILL TRACK ACROSS THE SOUTHERN HALF OF THE CWA THROUGH THE MORNING HOURS...AFFECTING KPIR AND KATY. CIGS WILL REMAIN VFR WITH THE PRECIPITATION...BUT VSBYS MAY BRIEFLY FALL INTO THE MVFR CATEGORY WITH THE THUNDERSTORMS. THE PRECIPITATION SHOULD EXIT THE AREA BY EARLY AFTERNOON...THEN VFR CONDITIONS WILL PREVAIL THROUGH THE REMAINDER OF THE TAF PERIOD. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...SERR SHORT TERM...SD LONG TERM...PARKIN AVIATION...PARKIN WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
522 AM CDT WED MAY 15 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 428 AM CDT WED MAY 15 2013 LINGERING MID LEVEL BOUNDARY AND SOME WEAKLY UNSTABLE 700-500 HPA LAPSE RATES CREATING SOME ISSUES WITH THE FORECAST EARLY THIS MORNING. WAVE TOPPING DEVELOPING RIDGE ALOFT AND NUDGING UP AGAINST NORTHWEST SOUTH DAKOTA ACTING TO INDUCE SOME CROSS FRONTAL FLOW... AND WEAK REGION OF HIGH BASED LIFT FROM NORTHWEST TO SOUTHEAST ACROSS THE STATE. MID LEVEL FRONTOGENETIC FORCING REMAINS FAIRLY STRONG MAINLY ALONG AND NORTH OF I90 THROUGH THE DAY... WEAKENING SOME BY AFTERNOON AS WAVE MOVES PAST. VERY DRY LOWER ATMOSPHERE IS CERTAINLY IMPACTING THE POTENTIAL EASTWARD SPREAD AND OVERALL COVERAGE OF WETTING RAINFALL. THE HRRR KEEP SLIPPING AWAY ON DEVELOPING PRECIP...PUSHING IT BACK AT LEAST AN HOUR OR TWO WITH SUCCESSIVE RUN DESPITE THE INCREASING PRESENCE ON RADAR OVER THE LAST HOUR OR TWO. HIGH RES MODELS SEEM TO HAVE THE RIGHT IDEA...AND SUPPORT FROM LARGER SCALE DYNAMICS MENTIONED ABOVE. INDICATIONS ON VARIOUS FORECAST SOUNDING FROM 100 TO 300 J/K ELEVATED INSTABILITY...SO WOULD NOT BE SURPRISED TO GET A FEW RUMBLES OF HIGH BASED THUNDER...EVEN WITH THE OVERALL PROBABILITY/ COVERAGE OF PRECIPITATION LIKELY LACKING...AND AT THIS POINT NOT WARRANTING MUCH MORE THAN A LOWER SCATTERED MENTION. SOME CONCERN THAT LINGERING CLOUDS AND ANY EVAPORATIVE EFFECTS WOULD HAVE AN IMPACT ON TEMPERATURES TODAY...BUT SHOULD START TO GET AT LEAST A DECENT AMOUNT OF SUNSHINE AFTER MAIN WAVE SHEARS BY TO THE NORTH...AND LINGERING DIV Q ACROSS THE SOUTH WEAKENS AS WELL. MIXING CENTERS AROUND THE MID TO UPPER 70S...AND DID NUDGE THIS JUST A BIT HIGHER FOR THE FAR WEST. TONIGHT LOOKS TO BE QUIETEST PERIOD OF THE FORECAST...WITH WEAK MID TO UPPER LEVEL RIDGING OVER THE AREA TONIGHT AHEAD OF NEXT WAVE. NAM AND GEM ACTUALLY A BIT FASTER IN BRINGING PRECIP CHANCE BACK INTO OUR SOUTHWEST LATE TONIGHT...HOWEVER BEST FORCING WITH WARM ADVECTION AND ADVANCING WAVE APPEARS TO REMAIN FOCUSED JUST WEST OF OUR AREA THROUGH 12Z AND WILL LEAVE TONIGHT DRY AS A RESULT. LIGHT WINDS AND RELATIVELY DRY AIR MASS WILL ALLOW FOR FAIR AMOUNT OF RADIATIONAL COOLING...AND LOWS IN THE LOWER 50S LOOK REASONABLE FOR MOST AREAS. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 428 AM CDT WED MAY 15 2013 MESSY PATTERN THROUGHOUT THE LONG TERM PERIOD OF THIS FORECAST...WITH DIFFICULTY PINPOINTING ANY PERIOD WHICH COULD BE SIGNIFICANTLY DRIER THAN ANOTHER. PERIOD STARTS WITH WARM FRONT AND ASSOCIATED WAVE MOVING ACROSS THE FORECAST AREA THURSDAY/THURSDAY NIGHT. NAM/GEM/ECMWF QUITE BULLISH IN PRODUCING FAIR AMOUNT OF PRECIP WITH THIS SYSTEM...WHILE THE GFS IS MUCH DRIER THOUGH STILL INDICATIVE OF SOME PRECIP CHANCE. 15/00Z NAM SEEMS TO BE SLIGHT OUTLIER IN SPEED WITH WHICH IS TRACKS THE WAVE AND ASSOCIATED PRECIP TO THE NORTHEAST ON THURSDAY...AND HAVE GENERALLY FOLLOWED SLOWER IDEA FOR NOW...KEEPING OUR NORTHEAST COUNTIES DRY UNTIL THURSDAY EVENING. PERSISTENT WARM ADVECTION WILL THEN LEAD TO INCREASING PRECIP CHANCE THROUGH THE OVERNIGHT HOURS THURSDAY NIGHT. TEMPERATURES SHOULD BE SEASONABLE WITH HIGHS THURSDAY IN THE MID TO UPPER 70S. INCREASING MOISTURE/CLOUD COVER WILL HOLD TEMPERATURES UP IN THE UPPER 50S THURSDAY NIGHT. MUCH OF FRIDAY/FRIDAY NIGHT COULD AGAIN BE BETWEEN PERIODS OF MORE WIDESPREAD/ORGANIZED PRECIPITATION...THOUGH EASTERN AREAS COULD SEE A FEW THUNDERSTORMS LINGER INTO THE MORNING...WHILE THE WEST HAS A CHANCE OF DEVELOPMENT FRIDAY NIGHT AS RETURN FLOW OF MOISTURE MOVES INTO CENTRAL SOUTH DAKOTA. WITH WARM FRONT EXPECTED TO BE NORTH OF THE AREA BY FRIDAY AFTERNOON...AND GENERAL LACK OF PRECIP ALONG WITH BREEZY SOUTH WINDS...SHOULD SEE DECENT MIXING TO HELP WARM TEMPS INTO THE MID 80S ACROSS THE WEST. DESPITE WARMER TEMPS AND POTENTIAL FOR SOME GUSTY WINDS...DO NOT EXPECT SIGNIFICANT FIRE DANGER FRIDAY AS WE SHOULD HAVE MUCH HIGHER BOUNDARY LAYER MOISTURE WITH EVEN MIXED OUT DEW POINTS HOLDING IN THE UPPER 50S TO AROUND 60. THAT MOISTURE ALONG WITH WEAK LOW LEVEL JET WILL HOLD OVERNIGHT LOWS IN THE LOWER TO MID 60S FOR FRIDAY NIGHT. SATURDAY INTO SATURDAY NIGHT CONTINUES TO LOOK LIKE MOST FAVORED PERIOD FOR ORGANIZED PRECIPITATION ACROSS THE REGION...AS BROAD WESTERN CONUS TROUGH BEGINS TO SHIFT EASTWARD INTO THE PLAINS. PRECIP SHOULD INITIALLY BE FOCUSED NEAR BOUNDARY ACROSS CENTRAL SOUTH DAKOTA BY SATURDAY AFTERNOON...WITH THUNDERSTORMS THEN EXPANDING EASTWARD ACROSS OUR FORECAST AREA SATURDAY NIGHT. THIS PERIOD CONTINUES TO BE GREATEST THREAT FOR SEVERE WEATHER FOR OUR FORECAST AREA...WITH STEEP MID LEVEL LAPSE RATES AND DEEP FORCING AHEAD OF TROUGH BRINGING POTENTIAL FOR HAIL/WIND. AS IS TYPICAL IN CONVECTIVE SEASON...MODELS NOT SHOWING A GREAT DEAL OF AGREEMENT IN TIMING/LOCATION OF BOUNDARIES FROM THIS POINT FORWARD. HOWEVER...THEY HAVE TRENDED TOWARD A FAVORED SOLUTION IN CLOSING OFF THE UPPER LOW SOMEWHERE IN THE CENTRAL/NORTHERN PLAINS BY SUNDAY NIGHT/MONDAY...WITH THE LOW THEN PERSISTING ACROSS THIS REGION THROUGH MUCH OF EARLY NEXT WEEK. THIS LEADS TO POTENTIAL FOR AT LEAST SCATTERED PRECIPITATION SUNDAY THROUGH TUESDAY...AND HAVE NOT STRAYED FAR FROM CONSENSUS GRIDS WHICH HOLD ONTO CHANCE RANGE POPS FOR THE LONGER RANGE. TEMPERATURES SHOWING LESS AGREEMENT LATE IN THE PERIOD...WITH LATEST ECMWF WRAPPING MUCH COLDER AIR AROUND THE BACK SIDE OF THE UPPER LOW BY MONDAY AND ESPECIALLY TUESDAY. FOR NOW WILL STICK WITH SOMEWHAT MORE MILD GFS/CONSENSUS SOLUTION WHICH... ALTHOUGH COOLER THAN THE MILD TEMPERATURES EXPECTED THROUGH THE WEEKEND...WILL KEEP HIGHS IN THE 60S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 521 AM CDT WED MAY 15 2013 ELEVATED INSTABILITY AND A DISTURBANCE MOVING ACROSS FAR NORTHERN SOUTH DAKOTA THIS MORNING WILL CONTINUE TO PRODUCE ISOLATED TO SCATTERED SHOWERS AND A FEW THUNDERSTORMS ACROSS THE AREA. OTHER THAN THE IMMEDIATE SHORT TERM AROUND KHON...NOT LIKELY TO HAVE A HIGH ENOUGH PROBABILITY OF THUNDER TO WARRANT MENTION IN THE TAFS. DESPITE PRECIPITATION...VERY HIGH BASED NATURE WILL MEAN THAT CONDITIONS SHOULD REMAIN VFR. THE PRECIPITATION SHOULD MOVE OUT OF THE IMMEDIATE AREA BY 18Z...AND DRY CONDITIONS ARE EXPECTED THROUGH 12Z THURSDAY. HOWEVER...SCATTERED THUNDERSTORMS SHOULD BE POISED SOUTHWEST OF THE KHON AREA TOWARD 12Z MOVING FROM ORIGINS IN WESTERN NEBRASKA AND SOUTHWEST SOUTH DAKOTA. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM...CHAPMAN/JH LONG TERM...JH AVIATION...CHAPMAN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
428 AM CDT WED MAY 15 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 428 AM CDT WED MAY 15 2013 LINGERING MID LEVEL BOUNDARY AND SOME WEAKLY UNSTABLE 700-500 HPA LAPSE RATES CREATING SOME ISSUES WITH THE FORECAST EARLY THIS MORNING. WAVE TOPPING DEVELOPING RIDGE ALOFT AND NUDGING UP AGAINST NORTHWEST SOUTH DAKOTA ACTING TO INDUCE SOME CROSS FRONTAL FLOW... AND WEAK REGION OF HIGH BASED LIFT FROM NORTHWEST TO SOUTHEAST ACROSS THE STATE. MID LEVEL FRONTOGENETIC FORCING REMAINS FAIRLY STRONG MAINLY ALONG AND NORTH OF I90 THROUGH THE DAY... WEAKENING SOME BY AFTERNOON AS WAVE MOVES PAST. VERY DRY LOWER ATMOSPHERE IS CERTAINLY IMPACTING THE POTENTIAL EASTWARD SPREAD AND OVERALL COVERAGE OF WETTING RAINFALL. THE HRRR KEEP SLIPPING AWAY ON DEVELOPING PRECIP...PUSHING IT BACK AT LEAST AN HOUR OR TWO WITH SUCCESSIVE RUN DESPITE THE INCREASING PRESENCE ON RADAR OVER THE LAST HOUR OR TWO. HIGH RES MODELS SEEM TO HAVE THE RIGHT IDEA...AND SUPPORT FROM LARGER SCALE DYNAMICS MENTIONED ABOVE. INDICATIONS ON VARIOUS FORECAST SOUNDING FROM 100 TO 300 J/K ELEVATED INSTABILITY...SO WOULD NOT BE SURPRISED TO GET A FEW RUMBLES OF HIGH BASED THUNDER...EVEN WITH THE OVERALL PROBABILITY/ COVERAGE OF PRECIPITATION LIKELY LACKING...AND AT THIS POINT NOT WARRANTING MUCH MORE THAN A LOWER SCATTERED MENTION. SOME CONCERN THAT LINGERING CLOUDS AND ANY EVAPORATIVE EFFECTS WOULD HAVE AN IMPACT ON TEMPERATURES TODAY...BUT SHOULD START TO GET AT LEAST A DECENT AMOUNT OF SUNSHINE AFTER MAIN WAVE SHEARS BY TO THE NORTH...AND LINGERING DIV Q ACROSS THE SOUTH WEAKENS AS WELL. MIXING CENTERS AROUND THE MID TO UPPER 70S...AND DID NUDGE THIS JUST A BIT HIGHER FOR THE FAR WEST. TONIGHT LOOKS TO BE QUIETEST PERIOD OF THE FORECAST...WITH WEAK MID TO UPPER LEVEL RIDGING OVER THE AREA TONIGHT AHEAD OF NEXT WAVE. NAM AND GEM ACTUALLY A BIT FASTER IN BRINGING PRECIP CHANCE BACK INTO OUR SOUTHWEST LATE TONIGHT...HOWEVER BEST FORCING WITH WARM ADVECTION AND ADVANCING WAVE APPEARS TO REMAIN FOCUSED JUST WEST OF OUR AREA THROUGH 12Z AND WILL LEAVE TONIGHT DRY AS A RESULT. LIGHT WINDS AND RELATIVELY DRY AIR MASS WILL ALLOW FOR FAIR AMOUNT OF RADIATIONAL COOLING...AND LOWS IN THE LOWER 50S LOOK REASONABLE FOR MOST AREAS. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 428 AM CDT WED MAY 15 2013 MESSY PATTERN THROUGHOUT THE LONG TERM PERIOD OF THIS FORECAST...WITH DIFFICULTY PINPOINTING ANY PERIOD WHICH COULD BE SIGNIFICANTLY DRIER THAN ANOTHER. PERIOD STARTS WITH WARM FRONT AND ASSOCIATED WAVE MOVING ACROSS THE FORECAST AREA THURSDAY/THURSDAY NIGHT. NAM/GEM/ECMWF QUITE BULLISH IN PRODUCING FAIR AMOUNT OF PRECIP WITH THIS SYSTEM...WHILE THE GFS IS MUCH DRIER THOUGH STILL INDICATIVE OF SOME PRECIP CHANCE. 15/00Z NAM SEEMS TO BE SLIGHT OUTLIER IN SPEED WITH WHICH IS TRACKS THE WAVE AND ASSOCIATED PRECIP TO THE NORTHEAST ON THURSDAY...AND HAVE GENERALLY FOLLOWED SLOWER IDEA FOR NOW...KEEPING OUR NORTHEAST COUNTIES DRY UNTIL THURSDAY EVENING. PERSISTENT WARM ADVECTION WILL THEN LEAD TO INCREASING PRECIP CHANCE THROUGH THE OVERNIGHT HOURS THURSDAY NIGHT. TEMPERATURES SHOULD BE SEASONABLE WITH HIGHS THURSDAY IN THE MID TO UPPER 70S. INCREASING MOISTURE/CLOUD COVER WILL HOLD TEMPERATURES UP IN THE UPPER 50S THURSDAY NIGHT. MUCH OF FRIDAY/FRIDAY NIGHT COULD AGAIN BE BETWEEN PERIODS OF MORE WIDESPREAD/ORGANIZED PRECIPITATION...THOUGH EASTERN AREAS COULD SEE A FEW THUNDERSTORMS LINGER INTO THE MORNING...WHILE THE WEST HAS A CHANCE OF DEVELOPMENT FRIDAY NIGHT AS RETURN FLOW OF MOISTURE MOVES INTO CENTRAL SOUTH DAKOTA. WITH WARM FRONT EXPECTED TO BE NORTH OF THE AREA BY FRIDAY AFTERNOON...AND GENERAL LACK OF PRECIP ALONG WITH BREEZY SOUTH WINDS...SHOULD SEE DECENT MIXING TO HELP WARM TEMPS INTO THE MID 80S ACROSS THE WEST. DESPITE WARMER TEMPS AND POTENTIAL FOR SOME GUSTY WINDS...DO NOT EXPECT SIGNIFICANT FIRE DANGER FRIDAY AS WE SHOULD HAVE MUCH HIGHER BOUNDARY LAYER MOISTURE WITH EVEN MIXED OUT DEW POINTS HOLDING IN THE UPPER 50S TO AROUND 60. THAT MOISTURE ALONG WITH WEAK LOW LEVEL JET WILL HOLD OVERNIGHT LOWS IN THE LOWER TO MID 60S FOR FRIDAY NIGHT. SATURDAY INTO SATURDAY NIGHT CONTINUES TO LOOK LIKE MOST FAVORED PERIOD FOR ORGANIZED PRECIPITATION ACROSS THE REGION...AS BROAD WESTERN CONUS TROUGH BEGINS TO SHIFT EASTWARD INTO THE PLAINS. PRECIP SHOULD INITIALLY BE FOCUSED NEAR BOUNDARY ACROSS CENTRAL SOUTH DAKOTA BY SATURDAY AFTERNOON...WITH THUNDERSTORMS THEN EXPANDING EASTWARD ACROSS OUR FORECAST AREA SATURDAY NIGHT. THIS PERIOD CONTINUES TO BE GREATEST THREAT FOR SEVERE WEATHER FOR OUR FORECAST AREA...WITH STEEP MID LEVEL LAPSE RATES AND DEEP FORCING AHEAD OF TROUGH BRINGING POTENTIAL FOR HAIL/WIND. AS IS TYPICAL IN CONVECTIVE SEASON...MODELS NOT SHOWING A GREAT DEAL OF AGREEMENT IN TIMING/LOCATION OF BOUNDARIES FROM THIS POINT FORWARD. HOWEVER...THEY HAVE TRENDED TOWARD A FAVORED SOLUTION IN CLOSING OFF THE UPPER LOW SOMEWHERE IN THE CENTRAL/NORTHERN PLAINS BY SUNDAY NIGHT/MONDAY...WITH THE LOW THEN PERSISTING ACROSS THIS REGION THROUGH MUCH OF EARLY NEXT WEEK. THIS LEADS TO POTENTIAL FOR AT LEAST SCATTERED PRECIPITATION SUNDAY THROUGH TUESDAY...AND HAVE NOT STRAYED FAR FROM CONSENSUS GRIDS WHICH HOLD ONTO CHANCE RANGE POPS FOR THE LONGER RANGE. TEMPERATURES SHOWING LESS AGREEMENT LATE IN THE PERIOD...WITH LATEST ECMWF WRAPPING MUCH COLDER AIR AROUND THE BACK SIDE OF THE UPPER LOW BY MONDAY AND ESPECIALLY TUESDAY. FOR NOW WILL STICK WITH SOMEWHAT MORE MILD GFS/CONSENSUS SOLUTION WHICH... ALTHOUGH COOLER THAN THE MILD TEMPERATURES EXPECTED THROUGH THE WEEKEND...WILL KEEP HIGHS IN THE 60S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1127 PM CDT TUE MAY 14 2013 VFR CONDITIONS WILL CONTINUE THROUGH 06Z THURSDAY. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM...CHAPMAN/JH LONG TERM...JH AVIATION...CHAPMAN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1127 PM CDT TUE MAY 14 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 211 PM CDT TUE MAY 14 2013 FRONT CONTINUES TO MOVE ACROSS THE CWA THIS AFTERNOON. RECORD HEAT OUT AHEAD OF THE FRONT WITH LOW TO EVEN MID 100S ACROSS NORTHWEST IOWA AND PORTIONS OF SOUTHWEST MINNESOTA...AND STILL LOW TO MID 90S BEHIND THE FRONT ACROSS SOUTHEAST SOUTH DAKOTA. WITH DEWPOINTS MIXING OUT...NOT MUCH IN THE WAY OF INSTABILITY AHEAD OF THE FRONT. ALTHOUGH THE HRRR AND RUC HAVE CONTINUED TO SHOW SOME ISOLATED DEVELOPMENT ALONG THE FRONT BY 22Z. GIVEN THAT BOTH OF THESE SHORT RANGE MODELS ARE DOING A PRETTY GOOD JOB WITH SURFACE TEMPS AND DEWPOINTS..THINK SOME ISOLATED CONVECTION MAY FIRE AS WE MIX THROUGH WHATEVER CAP THERE IS. HOWEVER LOOKS LIKE THIS THREAT IS MAINLY SOUTH AND SOUTHEAST OF OUR CWA...THUS WILL KEEP THE FORECAST DRY THROUGH THE EVENING. WEAK COLD AIR ADVECTION CONTINUES THROUGH THE NIGHT...WITH WINDS WEAKENING. THUS WHILE LOWS WILL BE ABOVE NORMAL...MAY STILL SEE THEM GET DOWN INTO THE LOW TO MID 50S BY MORNING IN MOST LOCATIONS. MID LEVEL FRONTAL BOUNDARY LINGERS OVERHEAD TONIGHT INTO TOMORROW...WITH A WEAK WAVE RIDING OVER THE RIDGE. SO WILL SEE A REGION OF WEAK LIFT AND DECENT MID LEVEL LAPSE RATES. HOWEVER THETAE ADVECTION IS PRETTY WEEK...AND LOW LEVELS WILL REMAIN VERY DRY. WILL PROBABLY SEE SOME ELEVATED CONVECTION FORM ACROSS WESTERN NEBRASKA AND SOUTH DAKOTA TONIGHT...WHICH WILL TRY TO MOVE EAST TOWARDS OUR AREA. HOWEVER GIVEN THE ABOVE LIMITATIONS...THINK THE CHANCE OF MEASURABLE PRECIP IN OUR CWA IS TOO LOW TO MENTION AT THIS TIME. HOWEVER CAN NOT RULE OUT AN ISOLATED SHOWER OR SOME SPRINKLES REACHING THE GROUND ANYTIME FROM LATE TONIGHT THROUGH THE DAY TOMORROW. HIGH TEMPERATURES A BIT TRICKY GIVEN CLOUD COVER POTENTIAL. BUT FEEL WE WILL SEE PERIODS OF SUN AS WELL...WITH GENERALLY PARTLY TO AT TIMES MOSTLY SUNNY SKIES. AND RECENTLY WE HAVE BEEN GETTING WARMER THAN JUST ABOUT EVERY GUIDANCE...SO DESPITE CLOUD COVER CONCERNS WENT AHEAD AND RAISED HIGHS A COUPLE DEGREES...GENERALLY IN THE UPPER 70S TO AROUND 80. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 325 PM CDT TUE MAY 14 2013 THE FRONT SOUTH OF THE AREA WILL BEGIN TO MOVE NORTH AS A WARM FRONT WEDNESDAY NIGHT AND SHOULD BEGIN TO BRING SOME MORE MOIST AND UNSTABLE AIR INTO THE AREA BY THE END OF THE NIGHT. LOW TEMPERATURES SHOULD BE NEAR SEASONAL VALUES BEFORE MOST OF THE HUMID AIR GETS HERE ON THURSDAY. THE THREAT OF THUNDERSTORMS IN WARM ADVECTION PATTERN NORTH OF THE FRONT MAY BEGIN IN THE SOUTH LATE WEDNESDAY NIGHT. THIS THREAT SHOULD GENERALLY BE AROUND FOR THE REST OF THE FORECAST...ALTHOUGH WILL KEEP POPS MINIMAL ON FRIDAY AS IT LOOKS LIKE THERE MAY BE A BREAK ON THAT DAY. THEN THE THREAT WILL INCREASE AGAIN FOR THE WEEKEND AS MAIN UPPER TROUGH APPROACHES...WITH THE PEAK THREAT SATURDAY NIGHT. A SEVERE THREAT OR MODESTLY HEAVY RAIN SEEMS POSSIBLE OVER THE WEEKEND. INSTABILITY AND MOISTURE UNCERTAIN WITH IT BEING WELL DISCUSSED ABOUT THE TOO HIGH GFS DEW POINTS. IN ANY EVENT TEMPERATURES WILL BE WARM DURING THE DAY BUT EVEN WARMER RELATIVE TO NORMAL AT NIGHT...OR NO REAL HOT SPELL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1127 PM CDT TUE MAY 14 2013 VFR CONDITIONS WILL CONTINUE THROUGH 06Z THURSDAY. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM...CHENARD LONG TERM... AVIATION...CHAPMAN
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
658 PM CDT THU MAY 16 2013 .UPDATE... JUST ISOLATED SHOWER AND TSTM ACTIVITY THUS FAR ACROSS THE MID STATE THIS EVENING. BETTER COVERAGE OF SHOWERS AND TSTMS EXISTS BACK TO OUR WEST ACROSS AR. MODELS ARE IN AGREEMENT WITH THIS DEEPER AREA OF MOISTURE SPREADING EASTWARD AND REACHING WESTERN PORTIONS OF MIDDLE TN TOWARD SUNRISE. HRRR FURTHER SUPPORTS AN INCREASE IN OUR POPS OVERNIGHT FOR MAINLY OUR WESTERN AREAS. THUS...WILL GO AHEAD AND MODIFY THE WEATHER GRIDS AND SEPARATE THE OVERNIGHT GRIDS INTO TWO...00Z-06Z AND 06Z-12Z. WILL EXPAND THE LIKELY POPS OVER OUR WEST AND MOVE THE CHC CATEGORY A LITTLE FURTHER EAST AS WELL. REMAINDER OF FCST IS IN GOOD SHAPE. SEE NO REASON FOR ANY FURTHER MODS. UPDATES OUT SHORTLY. && .PREV DISCUSSION... /ISSUED 312 PM CDT THU MAY 16 2013/ SHORT TERM...RIDGE OF HIGH PRESSURE SITUATED EAST OF MIDDLE TENNESSEE THIS AFTERNOON, ALLOWING ADVECTION OF WARM, MOIST AIR TO TAKE PLACE. LATEST LAPS SOUNDING SHOWS INSTABILITY GRADUALLY INCREASING WITH AFTERNOON HEATING, BUT ATMOSPHERE BELOW 600 MB IS STILL LARGELY DRY. LOOK FOR SATURATION TO GRADUALLY TAKE PLACE LATER TONIGHT AS TOMORROW S A SHORTWAVE APPROACHES MIDDLE TENNESSEE FROM THE WEST AND BEGINS TO SPREAD CONVECTION ACROSS THE MID STATE. LOOK FOR MAINLY SCATTERED ACTIVITY WEST OF THE PLATEAU OVERNIGHT, WITH POP`S INCREASING TOMORROW. CENTER OF UPPER LOW MOVES INTO SOUTHWESTERN KENTUCKY BY TOMORROW AFTERNOON ACCOMPANIED BY A GOOD BAND OF LIFT OVER OUR WESTERN COUNTIES. THUS, HAVE GONE WITH CATEGORICAL POPS FOR THOSE AREAS TOMORROW, RANGING TO 50% POPS ALONG THE UPPER CUMBERLAND. SHORTWAVE CONTINUES SLOWLY EASTWARD FRIDAY NIGHT, WITH SHOWERS AND THUNDERSTORMS LIKELY AREA-WIDE. ATMOSPHERIC MOISTURE REMAINS DEEP ON SATURDAY, ESPECIALLY NORTH AND EAST, WHERE SHOWERS AND THUNDERSTORMS WILL REMAIN LIKELY. WESTERN AREAS SHOULD START TO DRY OUT BY LATE SATURDAY NIGHT, AS UPPER LOW CENTER MOVES TO NEAR SOUTHWEST VIRGINIA BY 12Z SUNDAY. RIDGE OF HIGH PRESSURE BUILDS IN OVER THE AREA EARLY NEXT WEEK, ALLOWING FOR MORE DAYTIME SUNSHINE AND SENDING DAYTIME HIGHS PUSHING INTO THE MIDDLE AND UPPER 80S BOTH MONDAY AND TUESDAY. LONG TERM...DURING THE MIDDLE TO LATTER PART OF NEXT WEEK, EXPECT UPPER RIDGE TO PUSH EAST, ALLOWING FOR A MOIST SOUTHWEST FLOW TO DEVELOP FROM THE SOUTHERN PLAINS AND LOWER MISSISSIPPI RIVER VALLEY UP ACROSS THE TENNESSEE AND OHIO RIVER VALLEYS. SHOWERS AND THUNDERSTORMS WILL PROBABLY BECOME LIKELY AGAIN BY WEDNESDAY, WITH AT LEAST SMALL CHANCES FOR SHOWERS AND THUNDERSTORMS LINGERING INTO THURSDAY AS WELL. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 21
AREA FORECAST DISCUSSION
NWS CORPUS CHRISTI TX
1255 PM CDT WED MAY 15 2013 .DISCUSSION...NOTE AVIATION DISCUSSION. && .AVIATION...PREDOMINATE VFR CONDITIONS EXPECTED THIS AFTN EXCEPT BRIEF MVFR CONDITIONS PSBL NEAR ISOLD SHOWERS/THUNDERSTORMS. CONVECTION SHOULD END BY THIS EVENING. A TRANSITION TO MVFR CEILINGS GENERALLY EAST OF U.S. ROUTE 281 AFTER 06Z THURSDAY. NON-CONVECTIVE LLWS IS ANTICIPATED FOR ALI DRG THE 06-14Z THU PERIOD. A TRANSITION TO VFR CONDITIONS AREAWIDE AFTER 15Z THURSDAY. ONSHORE SFC WIND EXPECTED DURING THE TAF PERIOD WITH MODERATE/BREEZY CONDITIONS THIS AFTN/EARLY EVENING...LIGHT OVERNIGHT...THEN INCREASING TO MODERATE/BREEZY BY MID MORNING THURSDAY. && .PREV DISCUSSION... /ISSUED 635 AM CDT WED MAY 15 2013/ DISCUSSION...UPDATED FOR 12Z TAFS. AVIATION...SHOWERS AND THUNDERSTORMS ARE NOTED AT AND NEAR CRP AND VCT TAF SITES. LRD AND ALI STILL MAY SEE A FEW SHOWERS IN THE VICINITY THIS MORNING...BUT MOST OF THE ACTIVITY WILL REMAIN ALONG THE COAST. MVFR CONDITIONS WILL CONTINUE FOR MOST SITES THROUGH THE DAY...BUT LRD SHOULD IMPROVE TO VFR. BREEZY CONDITIONS ARE EXPECTED TO DEVELOP DURING THE DAY. PREV DISCUSSION... /ISSUED 355 AM CDT WED MAY 15 2013/ SHORT TERM (TODAY THROUGH THURSDAY)...CONTINUING TO WATCH CONVECTIVE DEVELOPMENT THIS MORNING. SO FAR TWO MAIN AREAS OF PRECIP...ONE STAYING NORTH OF THE FORECAST AREA...THE OTHER LARGELY STAYING SOUTH...BOTH ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE. THE ACTIVITY TO THE SOUTH IS STARTING TO INCLUDE A NORTHWARD DRIFT ALONG WITH ITS EASTWARD PROGRESSIONS. CLOUD TOPS ARE ALSO COOLING ACROSS ZAPATA AND JIM HOGG COUNTIES WITH SOME HIGHER REFLECTIVITY ACTIVITY DEVELOPING. THIS SHOULD PUSH INTO THE BRUSH COUNTRY AND COASTAL BEND AS THE MORNING GOES ON. STARTING TO GET SOME ADDITIONAL DEVELOPMENT INTO THE COASTAL BEND AT THIS TIME. MODELS CONTINUE TO INDICATE MOISTURE FLUX CONVERGENCE THROUGH THE AREA THIS MORNING AS WELL. MOST OF GOES SOUNDER PWAT PRODUCT THIS MORNING IS CONTAMINATED BY CLOUDS...BUT A FEW PIXELS SHOW UP INDICATING NEARLY 2 INCH PWATS IN THE AREA. 00HR RUC PWAT ANALYSIS SHOW AS MUCH AS 2.2 INCHES ALONG THE DEEP SOUTH TEXAS COAST. RUC FORECAST WOULD SUGGEST AROUND 2 INCH VALUES IN TO OUR AREA IN THE NEXT FEW HOURS. THESE VALUES WOULD BE AROUND THE +2 STANDARD DEVIATION VALUES FOR THIS TIME OF YEAR. RUC MAY BE A LITTLE HIGH WITH THESE NUMBERS THOUGH. GFS AND NAM BOTH ARE JUST ABOVE 1.9 INCHES. HAVE NOT CHANGED POP FORECAST MUCH FOR TODAY...KEEPING A 40 TO 50 POP FOR EASTERN AREAS DURING THE DAY. UPPER LEVEL ENERGY PUSHES OUT OF THE AREA LATER THIS AFTERNOON ENDING PRECIP CHANCES. HAVE JUST A LINGERING 20 POP IN THE EAST AFTER 00Z THIS EVENING. MID LEVEL WAA WILL THEN INCREASE A CAPPING INVERSION OVER THE AREA TONIGHT INTO THURSDAY. TEMPERATURES WARM A BIT TODAY IN THE WEST...BUT PRECIP IN THE EAST COULD KEEP THE BRUSH COUNTRY AND COASTAL BEND AT OR BELOW YESTERDAYS TEMPS. ADDITIONALLY...A THICK CLOUD COVER LOOKS TO PERSIST OVER THE AREA WITH STRATUS MAYBE JUST A COUPLE THOUSAND FEET UP ALL DAY. BY THURSDAY CLOUDS BEGIN TO CLEAR WEST TO EAST AND SHOULD ALLOW FOR WARMER TEMPS. LAREDO COULD BE NEAR 100. LONG TERM (THURSDAY NIGHT THROUGH TUESDAY)...STRONG CAP IS IN PLACE ACROSS SOUTH TEXAS LATE THIS WEEK THROUGH EARLY NEXT WEEK. PWATS DO INCREASE BACK UP THE RIO GRANDE OVER THE WEEKEND TO NEAR 1.5 INCHES. MODELS INDICATE THE TAIL END OF A WEAK SHORTWAVE MOVING OUT OF MEXICO AND ACROSS SOUTH TEXAS LATE SATURDAY INTO SUNDAY. CONVECTION MAY FIRE ALONG THE SIERRA MADRE LATE SATURDAY AFTERNOON AND MOVE TOWARDS THE RIO GRANDE SATURDAY EVENING...BUT STRENGTH OF CAP OVER THE REGION MAKES CONFIDENCE IN CONVECTION REACHING WESTERN CWA LOW...AND THEREFORE NO WX CURRENTLY MENTIONED. OTHERWISE LONG TERM WILL FEATURE WARM AND DRY CONDITIONS ACROSS SOUTH TEXAS WITH PERIODS OF BREEZY CONDITIONS. 12Z ECMWF HAD BEEN INDICATE WEAK FRONT APPROACHING NORTHERN CWA LATE TUESDAY (DAY 7) BUT HAS BACKED OFF TO THE NORTH IN THE 00Z RUN. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 73 87 74 90 75 / 20 10 10 10 10 VICTORIA 72 85 74 88 73 / 20 10 10 10 10 LAREDO 73 100 73 99 74 / 10 10 10 10 10 ALICE 70 91 73 91 74 / 10 10 10 10 10 ROCKPORT 74 83 74 84 74 / 20 10 10 10 10 COTULLA 71 97 73 98 73 / 10 10 10 10 10 KINGSVILLE 72 89 74 91 75 / 10 10 10 10 10 NAVY CORPUS 74 84 73 84 74 / 20 10 10 10 10 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ WC/87...AVIATION
AREA FORECAST DISCUSSION
NWS CORPUS CHRISTI TX
635 AM CDT WED MAY 15 2013 .DISCUSSION...UPDATED FOR 12Z TAFS. && .AVIATION...SHOWERS AND THUNDERSTORMS ARE NOTED AT AND NEAR CRP AND VCT TAF SITES. LRD AND ALI STILL MAY SEE A FEW SHOWERS IN THE VICINITY THIS MORNING...BUT MOST OF THE ACTIVITY WILL REMAIN ALONG THE COAST. MVFR CONDITIONS WILL CONTINUE FOR MOST SITES THROUGH THE DAY...BUT LRD SHOULD IMPROVE TO VFR. BREEZY CONDITIONS ARE EXPECTED TO DEVELOP DURING THE DAY. && .PREV DISCUSSION... /ISSUED 355 AM CDT WED MAY 15 2013/ SHORT TERM (TODAY THROUGH THURSDAY)...CONTINUING TO WATCH CONVECTIVE DEVELOPMENT THIS MORNING. SO FAR TWO MAIN AREAS OF PRECIP...ONE STAYING NORTH OF THE FORECAST AREA...THE OTHER LARGELY STAYING SOUTH...BOTH ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE. THE ACTIVITY TO THE SOUTH IS STARTING TO INCLUDE A NORTHWARD DRIFT ALONG WITH ITS EASTWARD PROGRESSIONS. CLOUD TOPS ARE ALSO COOLING ACROSS ZAPATA AND JIM HOGG COUNTIES WITH SOME HIGHER REFLECTIVITY ACTIVITY DEVELOPING. THIS SHOULD PUSH INTO THE BRUSH COUNTRY AND COASTAL BEND AS THE MORNING GOES ON. STARTING TO GET SOME ADDITIONAL DEVELOPMENT INTO THE COASTAL BEND AT THIS TIME. MODELS CONTINUE TO INDICATE MOISTURE FLUX CONVERGENCE THROUGH THE AREA THIS MORNING AS WELL. MOST OF GOES SOUNDER PWAT PRODUCT THIS MORNING IS CONTAMINATED BY CLOUDS...BUT A FEW PIXELS SHOW UP INDICATING NEARLY 2 INCH PWATS IN THE AREA. 00HR RUC PWAT ANALYSIS SHOW AS MUCH AS 2.2 INCHES ALONG THE DEEP SOUTH TEXAS COAST. RUC FORECAST WOULD SUGGEST AROUND 2 INCH VALUES IN TO OUR AREA IN THE NEXT FEW HOURS. THESE VALUES WOULD BE AROUND THE +2 STANDARD DEVIATION VALUES FOR THIS TIME OF YEAR. RUC MAY BE A LITTLE HIGH WITH THESE NUMBERS THOUGH. GFS AND NAM BOTH ARE JUST ABOVE 1.9 INCHES. HAVE NOT CHANGED POP FORECAST MUCH FOR TODAY...KEEPING A 40 TO 50 POP FOR EASTERN AREAS DURING THE DAY. UPPER LEVEL ENERGY PUSHES OUT OF THE AREA LATER THIS AFTERNOON ENDING PRECIP CHANCES. HAVE JUST A LINGERING 20 POP IN THE EAST AFTER 00Z THIS EVENING. MID LEVEL WAA WILL THEN INCREASE A CAPPING INVERSION OVER THE AREA TONIGHT INTO THURSDAY. TEMPERATURES WARM A BIT TODAY IN THE WEST...BUT PRECIP IN THE EAST COULD KEEP THE BRUSH COUNTRY AND COASTAL BEND AT OR BELOW YESTERDAYS TEMPS. ADDITIONALLY...A THICK CLOUD COVER LOOKS TO PERSIST OVER THE AREA WITH STRATUS MAYBE JUST A COUPLE THOUSAND FEET UP ALL DAY. BY THURSDAY CLOUDS BEGIN TO CLEAR WEST TO EAST AND SHOULD ALLOW FOR WARMER TEMPS. LAREDO COULD BE NEAR 100. LONG TERM (THURSDAY NIGHT THROUGH TUESDAY)...STRONG CAP IS IN PLACE ACROSS SOUTH TEXAS LATE THIS WEEK THROUGH EARLY NEXT WEEK. PWATS DO INCREASE BACK UP THE RIO GRANDE OVER THE WEEKEND TO NEAR 1.5 INCHES. MODELS INDICATE THE TAIL END OF A WEAK SHORTWAVE MOVING OUT OF MEXICO AND ACROSS SOUTH TEXAS LATE SATURDAY INTO SUNDAY. CONVECTION MAY FIRE ALONG THE SIERRA MADRE LATE SATURDAY AFTERNOON AND MOVE TOWARDS THE RIO GRANDE SATURDAY EVENING...BUT STRENGTH OF CAP OVER THE REGION MAKES CONFIDENCE IN CONVECTION REACHING WESTERN CWA LOW...AND THEREFORE NO WX CURRENTLY MENTIONED. OTHERWISE LONG TERM WILL FEATURE WARM AND DRY CONDITIONS ACROSS SOUTH TEXAS WITH PERIODS OF BREEZY CONDITIONS. 12Z ECMWF HAD BEEN INDICATE WEAK FRONT APPROACHING NORTHERN CWA LATE TUESDAY (DAY 7) BUT HAS BACKED OFF TO THE NORTH IN THE 00Z RUN. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 85 73 87 74 90 / 50 20 10 10 10 VICTORIA 83 72 85 74 88 / 50 20 10 10 10 LAREDO 93 73 100 73 99 / 20 10 10 10 10 ALICE 87 70 91 73 91 / 40 10 10 10 10 ROCKPORT 83 74 83 74 84 / 50 20 10 10 10 COTULLA 91 71 97 73 98 / 30 10 10 10 10 KINGSVILLE 87 72 89 74 91 / 40 10 10 10 10 NAVY CORPUS 80 74 84 73 84 / 50 20 10 10 10 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ PZ/83...AVIATION
AREA FORECAST DISCUSSION
NWS CORPUS CHRISTI TX
355 AM CDT WED MAY 15 2013 .SHORT TERM (TODAY THROUGH THURSDAY)...CONTINUING TO WATCH CONVECTIVE DEVELOPMENT THIS MORNING. SO FAR TWO MAIN AREAS OF PRECIP...ONE STAYING NORTH OF THE FORECAST AREA...THE OTHER LARGELY STAYING SOUTH...BOTH ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE. THE ACTIVITY TO THE SOUTH IS STARTING TO INCLUDE A NORTHWARD DRIFT ALONG WITH ITS EASTWARD PROGRESSIONS. CLOUD TOPS ARE ALSO COOLING ACROSS ZAPATA AND JIM HOGG COUNTIES WITH SOME HIGHER REFLECTIVITY ACTIVITY DEVELOPING. THIS SHOULD PUSH INTO THE BRUSH COUNTRY AND COASTAL BEND AS THE MORNING GOES ON. STARTING TO GET SOME ADDITIONAL DEVELOPMENT INTO THE COASTAL BEND AT THIS TIME. MODELS CONTINUE TO INDICATE MOISTURE FLUX CONVERGENCE THROUGH THE AREA THIS MORNING AS WELL. MOST OF GOES SOUNDER PWAT PRODUCT THIS MORNING IS CONTAMINATED BY CLOUDS...BUT A FEW PIXELS SHOW UP INDICATING NEARLY 2 INCH PWATS IN THE AREA. 00HR RUC PWAT ANALYSIS SHOW AS MUCH AS 2.2 INCHES ALONG THE DEEP SOUTH TEXAS COAST. RUC FORECAST WOULD SUGGEST AROUND 2 INCH VALUES IN TO OUR AREA IN THE NEXT FEW HOURS. THESE VALUES WOULD BE AROUND THE +2 STANDARD DEVIATION VALUES FOR THIS TIME OF YEAR. RUC MAY BE A LITTLE HIGH WITH THESE NUMBERS THOUGH. GFS AND NAM BOTH ARE JUST ABOVE 1.9 INCHES. HAVE NOT CHANGED POP FORECAST MUCH FOR TODAY...KEEPING A 40 TO 50 POP FOR EASTERN AREAS DURING THE DAY. UPPER LEVEL ENERGY PUSHES OUT OF THE AREA LATER THIS AFTERNOON ENDING PRECIP CHANCES. HAVE JUST A LINGERING 20 POP IN THE EAST AFTER 00Z THIS EVENING. MID LEVEL WAA WILL THEN INCREASE A CAPPING INVERSION OVER THE AREA TONIGHT INTO THURSDAY. TEMPERATURES WARM A BIT TODAY IN THE WEST...BUT PRECIP IN THE EAST COULD KEEP THE BRUSH COUNTRY AND COASTAL BEND AT OR BELOW YESTERDAYS TEMPS. ADDITIONALLY...A THICK CLOUD COVER LOOKS TO PERSIST OVER THE AREA WITH STRATUS MAYBE JUST A COUPLE THOUSAND FEET UP ALL DAY. BY THURSDAY CLOUDS BEGIN TO CLEAR WEST TO EAST AND SHOULD ALLOW FOR WARMER TEMPS. LAREDO COULD BE NEAR 100. && .LONG TERM (THURSDAY NIGHT THROUGH TUESDAY)...STRONG CAP IS IN PLACE ACROSS SOUTH TEXAS LATE THIS WEEK THROUGH EARLY NEXT WEEK. PWATS DO INCREASE BACK UP THE RIO GRANDE OVER THE WEEKEND TO NEAR 1.5 INCHES. MODELS INDICATE THE TAIL END OF A WEAK SHORTWAVE MOVING OUT OF MEXICO AND ACROSS SOUTH TEXAS LATE SATURDAY INTO SUNDAY. CONVECTION MAY FIRE ALONG THE SIERRA MADRE LATE SATURDAY AFTERNOON AND MOVE TOWARDS THE RIO GRANDE SATURDAY EVENING...BUT STRENGTH OF CAP OVER THE REGION MAKES CONFIDENCE IN CONVECTION REACHING WESTERN CWA LOW...AND THEREFORE NO WX CURRENTLY MENTIONED. OTHERWISE LONG TERM WILL FEATURE WARM AND DRY CONDITIONS ACROSS SOUTH TEXAS WITH PERIODS OF BREEZY CONDITIONS. 12Z ECMWF HAD BEEN INDICATE WEAK FRONT APPROACHING NORTHERN CWA LATE TUESDAY (DAY 7) BUT HAS BACKED OFF TO THE NORTH IN THE 00Z RUN. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 85 73 87 74 90 / 50 20 10 10 10 VICTORIA 83 72 85 74 88 / 50 20 10 10 10 LAREDO 93 73 100 73 99 / 20 10 10 10 10 ALICE 87 70 91 73 91 / 40 10 10 10 10 ROCKPORT 83 74 83 74 84 / 50 20 10 10 10 COTULLA 91 71 97 73 98 / 30 10 10 10 10 KINGSVILLE 87 72 89 74 91 / 40 10 10 10 10 NAVY CORPUS 80 74 84 73 84 / 50 20 10 10 10 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ PZ/83...SHORT TERM JR/76...LONG TERM
AREA FORECAST DISCUSSION
NWS BROWNSVILLE TX
1235 AM CDT WED MAY 15 2013 .DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW. && .AVIATION...KBRO RADAR SHOWS MAINLY ISOLATED LIGHT RAIN SHOWERS ACROSS THE VALLEY WITH MORE DEVELOPING UPSTREAM INTO NORTHERN MEXICO AS ANOTHER PERTURBATION MOVES ACROSS THAT AREA. THERE ARE MVFR LOW CLOUDS SNEAKING AROUND UNDERNEATH MID LEVEL DECK WITH HEIGHTS AROUND 025. SHOWERS SHOULD CONTINUE TO DEVELOP AND MOVE ACROSS THIS MORNING THEN ANOTHER SHOT OF SHOWERS WEDNESDAY AFTERNOON BEFORE UPPER LEVEL LOW DEPARTS THE AREA. WINDS WILL INCREASE TODAY AS LOW PRESSURE DEVELOPS OVER THE HIGH PLAINS WITH GUSTS TO 25 KNOTS POSSIBLE THROUGH THE DAY. && .PREV DISCUSSION... /ISSUED 633 PM CDT TUE MAY 14 2013/ DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW. AVIATION...DUAL CLOUDS DECKS CONTINUE ACROSS SOUTH TEXAS...WITH LOWER DECK FROM 3000 TO 4000 FEET DRIFTING TO THE NW AND MIDLEVEL DECK RACING OFF TO THE NE. CLOUD DECK WILL REMAIN THROUGH THE NIGHT...WITH LOWER DECK SLOWLY LOWERING TO AROUND 2000 BY MORNING. PROB30 RAIN CHANCES STARTING AT MIDNIGHT AS THE NEXT SYSTEM MOVES INTO THE REGION...WITH SHOWERS ALREADY SHOWING UP ON RADAR TO THE SW. OCCASIONAL RAINFALL WILL CONTINUE TOMORROW...MAINLY BEFORE NOON. RAIN WILL REMAIN LIGHT...WITH ISOLATED LIGHTNING STRIKES POSSIBLE. PREV DISCUSSION... /ISSUED 155 PM CDT TUE MAY 14 2013/ SHORT TERM.../TONIGHT THROUGH WEDNESDAY NIGHT/...EVEN THOUGH THE LATEST RUC13 MODEL RUNS CONTINUE TO SHOW SHOWERS DEVELOPING ACROSS THE CWA THIS AFTERNOON...RADAR AND SATELLITE IMAGES INDICATE NOT MUCH IN THE WAY OF RAIN DEVELOPING AS OF YET. SURFACE INSTABILITY IS MARGINAL ACROSS THE RIO GRANDE VALLEY AND THE CLOUD COVER MAY BE INHIBITING THE INSTABILITY. IN ADDITION...WATER VAPOR SAT IMAGES AND NAM80 500MB VORTICITY ANALYSIS INDICATE NEGATIVE VORT CENTER JUST TO THE WEST OF THE AREA. CURRENT FORECAST THINKING IS THAT AS THE 500MB LOW ACROSS NORTHWEST MEXICO IS KICKED EASTWARD WITH THE SHORTWAVE TROUGH MOVING INTO SOUTHERN CALIFORNIA...SHOWERS AND THUNDERSTORMS WILL DEVELOP LATER THIS AFTERNOON INTO THIS EVENING ACROSS THE MEXICAN PLATEAU AND MOVE EASTWARD INTO THE WESTERN PORTIONS OF THE CWA TONIGHT INTO EARLY WEDNESDAY. WITH THAT SAID...WILL ADJUST TIMING OF POPS TONIGHT INTO WED NIGHT AND KEEP AT LEAST A CHANCE OF RAIN ACROSS MOST OF THE AREA THROUGH WED AFTERNOON. RAIN CHANCES SHOULD DIMINISH WED AFTERNOON INTO WED EVENING AS SUBSIDENCE WILL INCREASE ACROSS SOUTHWEST TX AS THE UPPER LEVEL LOW MOVES ACROSS NORTHWEST TX WEDNESDAY. LONG TERM.../THURSDAY THROUGH TUESDAY NIGHT/... LOW PRESSURE SYSTEM OVER BAJA CA WILL QUICKLY MOVE ACROSS SOUTH CENTRAL TEXAS WED INTO THU WITH SURFACE HIGH PRESSURE TO THE EAST MOVING SOUTHWARD OVER THE GULF WATERS AS IT INTERACTS WITH THE LOW PRESSURE OVER WEST TEXAS. AS THIS SYSTEM LIFTS TO THE NORTHEAST... THE SURFACE WINDS WILL RETURN TO THE SOUTHEAST ACROSS SOUTH TEXAS AND THE GRADIENT IN RETURN WILL STRENGTHEN. EXPECT BREEZE CONDITIONS BETWEEN 20 TO 25 MPH THURSDAY AFTERNOON. MOST OF THE MOISTURE SEEN IN THE LAST FEW DAYS WILL DROP DRAMATICALLY ACROSS THE AREA WITH THE BUFF SOUNDING NEAR KBRO SHOWING THE INFILTRATION OF THE DRIER AIR IN THE UPPER AND MID LEVEL OF THE ATMOSPHERE AND A DROP IN THE PWAT VALUES TO 1.34 INCHES AND INTO 1.10 INCHES TOWARDS THE WEST. THE DRIER AIR MASS FROM THE RIDGE BUILDING ACROSS THE WESTERN PLAINS WILL SET UP THAT DRIER AND WARM PATTERN FOR MOST OF THE LONG TERM FORECAST. HIGH TEMPERATURES THURSDAY THROUGH SUNDAY WILL BE WARM AND HUMID REACHING THE MID TO UPPER 90S THROUGH THE WEEK. ANOTHER TROUGH DIGS SOUTHWARD ALONG BAJA CALIFORNIA AND SWING NORTHEASTWARD INTO THE CENTRAL PLAINS SATURDAY AND SUNDAY. THE MAIN IMPACT WITH THIS SYSTEM FOR SOUTH TEXAS WILL BE THE SE WINDS AND THE ABUNDANT WARM TEMPERATURES ACROSS THE CWA WITH NO CONVECTION AS THE SYSTEM REMAINS NORTH OF THE CWA. EXPECT SURFACE GRADIENT TO INCREASE WITH BREEZE TO CONDITIONS THIS WEEKEND. NEXT WEEK...THE TROUGH WILL CONTINUE TO MOVE NORTHEAST AND STRENGTHEN ITS SURFACE TROUGH OVER NORTH CENTRAL PLAINS. THIS WILL CONTINUE TO KEEP THE AREA UNDER SOUTHEAST WINDS ACROSS THE CWA. BY TUESDAY...THE HIGH PRESSURE ALOFT BUILDS FROM THE SOUTH AND A VERY WEAK GRADIENT AT THE SURFACE RETURNS. LOW TEMPERATURES FOR MUCH OF THE LONG TERM FORECAST REMAIN IN THE MID 70S ACROSS THE AREA. MARINE...TONIGHT THROUGH WEDNESDAY NIGHT...SEAS WERE NEAR 4 FEET WITH SOUTHEAST WINDS NEAR 10 KNOTS AT BUOY020 EARLY THIS AFTERNOON. WINDS WILL INCREASE ACROSS THE COASTAL WATERS TONIGHT AS THE PRESSURE GRADIENT INCREASES ACROSS THE WESTERN GULF OF MEXICO. MODERATE TO STRONG SOUTHEAST WINDS WILL PREVAIL TONIGHT WITH SCEC CONDITIONS LIKELY OFFSHORE. THE SCEC CONDITIONS WILL PERSIST WEDNESDAY INTO WED NIGHT...ESPECIALLY OFFSHORE...AS THE PRESSURE GRADIENT REMAINS STRONG ACROSS THE LOWER TEXAS COAST. THURSDAY THROUGH TUESDAY... THE UPPER LEVEL SYSTEM OVER THE BAJA CA WILL FINALLY BEGIN TO MOVE NORTHEAST WEDNESDAY INTO THURSDAY LIMITING THE AREA OF ANY CONVECTION. THE SURFACE HIGH PRESSURE OVER THE SOUTHEAST PLAINS WILL BEGIN TO SHIFT SOUTH OVER THE GULF WATERS SHIFTING WINDS ACROSS THE GULF TOWARDS THE SE. WINDS WILL INCREASE THURSDAY AFTERNOON WITH POSSIBLE SCA FOR MUCH OF THE DAY AND EARLY EVENING AS WINDS INCREASE. THIS SE FLOW WILL PREVAIL FOR MUCH OF THE LONG TERM FORECAST BUT WILL WEAKEN BY NEXT WEEK. SEAS WILL BE BETWEEN 4 TO 5 FEET OVER THE GULF WATERS AS THERE WILL BE A LONG DURATION FETCH OVER THE GULF. THE UPPER AND LOWER FLOW WILL WEAKEN AND KEEP THE WAVE HEIGHT 5 FEET OR LESS. && .BRO WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT: HTTP://WEATHER.GOV/RGV 55/68
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
950 PM CDT THU MAY 16 2013 .UPDATE...BEEFED UP CLOUD COVER FOR MUCH OF THE NIGHT AS EXPECT UPSTREAM CONVECTION TO CONTINUE SPREADING NORTHEAST. ALSO...WEAKER LOW LEVEL WARM AIR AND MOISTURE ADVECTION TRIGGERING A SMALL LINE OF SHOWERS IN EASTERN IA SOUTH OF KDBQ. BOTH HRRR AND WRF-4L CARRY CONVECTION FARTHER EAST INTO SOUTH CENTRAL AND PORTIONS OF SOUTHEAST WI BY 12Z. WHILE LOW TO MID LEVEL LAYER RH INCREASES...LAYER Q-VECTOR CONVERGENCE ALSO INCREASES LATE TONIGHT. ALREADY INCREASED EASTWARD EXTENT AND PUSHED START TIME UP SLIGHTLY...BUT MAY NEED TO PUSH UP EVEN FARTHER AND EXPAND INTO PARTS OF SOUTHEAST WI. && .AVIATION/06Z TAFS/...VFR CONDITIONS TO CONTINUE. THREAT FOR THUNDER INCREASES FRI MRNG AND CONTINUES INTO THE EVENING...ESPECIALLY AT KMSN. HOWEVER UNCERTAINTY REGARDING TIMING SO WL CONT TO USE VCNTY REMARK. DRIER AIR FEED IN EASTERN AREAS SO WL NOT INTRODUCE ANY T ATTM. && .PREV DISCUSSION... /ISSUED 331 PM CDT THU MAY 16 2013/ VERY SHORT TERM...TONIGHT AND FRIDAY. FORECAST CONFIDENCE... MEDIUM A SLIGHT CHANCE FOR SHOWERS ACROSS THE NORTHWEST FORECAST AREA WAS HELD ONTO THROUGH EARLY EVENING. CURRENTLY...THERE IS A LOT OF CUMULUS DEVELOPMENT IN THE NORTHEAST...BUT NO SIGNS OF PRECIPITATION. MAY HAVE TO REMOVE THESE POPS BY LATE AFTERNOON IF LACK OF DEVELOPMENT PERSISTS. MODELS HAVE BACKED OFF AS WELL...SO LOOKING LESS LIKELY BY THE HOUR. DEW POINT DEPRESSIONS ARE ON THE ORDER OF 40 DEGREES AT THE MOMENT ACROSS THE NORTHWEST...SO THE DRY AIR IS LIKELY CONTRIBUTING TO THE LACK OF DEVELOPMENT. SHOULD BE DRY THEN THROUGH THE MAJORITY OF THE NIGHT. THE HRRR TRIES TO SNEAK SOME ACTIVITY INTO THE SW A BIT EARLIER THAN OTHER MODELS...BUT GENERALLY HELD OFF ON POPS UNTIL EARLY TOMORROW MORNING. AS THE LAKE AIR MASS CONTINUES TO PUSH INLAND UNDER EASTERLY WINDS...LOWS TONIGHT SHOULD NEAR NORMAL VALUES...MAINLY IN THE UPPER 40S TO LOW 50S. WILL HAVE A BAROCLINIC ZONE STRETCHED NORTHWEST TO SOUTHEAST ACROSS THE FORECAST AREA ON FRIDAY...WHILE A WEAK SHORTWAVE APPROACHES THE AREA. THESE FEATURES WILL LIKELY COMBINE TO KICK OFF SHOWER AND THUNDERSTORM ACTIVITY TOMORROW...PARTICULARLY ACROSS THE WEST AND SOUTHWEST TOWARD THE MILDER AIR. A COOL AND STABLE AIR MASS OFF THE LAKE WILL LIKE INHIBIT DEVELOPMENT IN THE EAST...SO KEPT POPS LOW. WILL SEE GOOD SPREAD IN HIGH TEMPS TOMORROW...WITH HIGHS LIKELY NOT GETTING OUT OF THE 50S ALONG THE LAKESHORE UNDER ONSHORE WINDS...TO THE LOW 70S IN THE SOUTHWEST. SHORT TERM...FRIDAY NIGHT THROUGH SUNDAY. FRIDAY NIGHT...FORECAST CONFIDENCE MODELS TAKE PRECIPITATION MAXIMA AT THE START OF THE PERIOD TO THE NORTH AND SOUTH OF THE FORECAST AREA WITH DEPARTING SHORT WAVES. LINGERING Q-VECTOR CONVERGENCE SUPPORT A GRADIENT OF CHANCE POPS...WITH THE HIGHER CHANCES NORTH...DIMINISHING AFTER 06Z SATURDAY. WITH WARM FRONT JUST PUSHING INTO THE FAR SW...WILL SEE A NEARLY 10-DEGREE DIFFERENCE WITH OVERNIGHT LOWS...WITH UPPER 40S IN THE NORTHEAST AND UPPER 50S IN THE FAR SW. SATURDAY...FORECAST CONFIDENCE MEDIUM. ENOUGH INSTABILITY AS DAYTIME HEATING/MIXING KICK IN...AND LOW-LEVEL CONVERGENCE AS WARM FRONT STALLS AND BECOMES A STATIONARY FRONT THROUGH THE MIDDLE PORTIONS OF THE CWA...TO WARRANT LOW-END POPS. SOME OF THE HIGHER INSTABILITY IS PREDICATED ON HIGHER THAN EXPECTED MODEL SURFACE DEW POINTS...A RECENT PROBLEM ON THE MODELS...SO HOLDING TO ONLY SLIGHT CHANCE POPS APPEARS APPROPRIATE. WILL SEE A STRONG TEMPERATURE CONTRAST ACROSS THE STATIONARY BOUNDARY WITH MID-UPPER 70S IN THE SW 1/2....AND UPPER 60S TO LOW 70S NE HALF. SATURDAY NIGHT...FORECAST CONFIDENCE HIGH. RIDGING AHEAD OF DEEPENING WAVE KEEPS AREA DRY. EASTERLY WINDS BRING UPPER 40S-LOW 50S ALONG THE KETTLE MORAINE AND EAST...AND IN THE MID TO UPPER 50S TO THE WEST WITH LOW 60S IN THE SOUTHWEST. LONG TERM... THIS PERIOD DOMINATED BY IMPACT OF CLOSED...NEARLY-STACKED LOW AS IT MOVES/FILLS OVER THE UPPER MIDWEST. CHANCES FOR THUNDER EACH PERIOD FROM SUNDAY NIGHT INTO WEDNESDAY WITH LOBES OF VORTICITY ROTATING AROUND CENTRAL CIRCULATION PROVIDING LIFT TO A WARM...MOIST UNSTABLE AIR MASS FEEDING INTO THE REGION ON SRLY FLOW AHEAD OF TROUGH. CIPS ANALOGS HAS INCREASING PROBABILITIES MOVING INTO SW WI MONDAY/MONDAY NIGHT...WITH SPC DAY 4-8 COMPOSITE OUTLOOK BRUSHING SOUTHWEST WISCONSIN ON DAYS 4 AND 5. SOME QUESTION AS TO EVOLUTION OF SYSTEM...12Z ECMWF SLOWLY OPENS THE SYSTEM AND MOVES IT SOUTHEAST AS IT PHASES WITH A SHORT WAVE DROPPING THROUGH EASTERN ONTARIO/WESTERN QUEBEC...WHILE THE GFS HAS THE LOW FILL AND SHEAR OUT OVER THE WESTERN GREAT LAKES. EITHER SOLUTION KEEPS THE MAJORITY OF THE EXTENDED WITH PCPN CHANCES UNTIL THE REMNANT LOW/TROUGH DROPS SOUTHEAST BY THURSDAY/THURSDAY NIGHT. SHOULD SEE MODE CHANGE FROM THUNDER TO RAIN SHOWERS WEDNESDAY NIGHT AND THURSDAY AS MID-LEVEL OCCLUSION PUSHES THE MORE UNSTABLE AIR MASS TO THE EAST. AVIATION/00Z TAFS/... VFR CONDITIONS WILL PERSIST THROUGH FRIDAY. SHOULD SEE MAINLY DRY WEATHER THIS EVENING AND OVERNIGHT. THERE WILL BE A CHANCE FOR SHOWERS AND STORMS FRIDAY...THE BEST CHANCE IN THE LATE MORNING AND AFTERNOON WEST OF A FOND DU LAC TO JANESVILLE LINE. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ MBK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
613 PM CDT THU MAY 16 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 343 PM CDT THU MAY 16 2013 WEAK HIGH PRESSURE WAS PROVIDING DRY AND QUIET WEATHER ACROSS THE FORECAST AREA LATE THIS AFTERNOON. MEANWHILE...A SHORTWAVE WAS MOVING ACROSS WESTERN/CENTRAL NEBRASKA GENERATING SHOWERS AND THUNDERSTORMS ACROSS THESE AREAS. A WARM FRONT WAS SITUATED FROM NORTHEAST NEBRASKA STRETCHING SOUTHEAST INTO SOUTH CENTRAL IOWA THROUGH CENTRAL ILLINOIS. THE WAVE WILL PUSH EAST TONIGHT WITH SHOWERS AND THUNDERSTORMS SPREADING INTO SOUTHWEST MINNESOTA AND NORTHWEST IOWA LATE THIS AFTERNOON INTO THIS EVENING. THE WAVE IS EXPECTED TO SLIDE ACROSS NORTHERN IOWA/SOUTHERN MINNESOTA LATE TONIGHT...EDGING INTO THE FORECAST AREA AFTER MIDNIGHT TONIGHT. LOCATIONS WEST OF HIGHWAY 52 WILL SEE THIS ACTIVITY MOVE IN BETWEEN MIDNIGHT AND 3AM...THEN IT WILL SPREAD EAST TO ALONG THE MISSISSIPPI RIVER AROUND SUNRISE. 850 MB MOISTURE TRANSPORT FOCUSES MAINLY ALONG AND NORTH OF THE INTERSTATE 90 CORRIDOR FRIDAY MORNING INTO EARLY FRIDAY AFTERNOON. FORECAST MODELS ARE SUGGESTING A MORE NORTHERLY TRACK WITH THE CLUSTER OF SHOWERS AND STORMS SO HAVE INCREASED PRECIPITATION CHANCES ACROSS SOUTHEAST MINNESOTA THROUGH NORTH CENTRAL WISCONSIN. THE WARM FRONT IS EXPECTED LIFT NORTH SLIGHTLY ON FRIDAY AS A POTENT TROUGH DIGS INTO THE SOUTHWEST CONUS AND SURFACE LOW PRESSURE DEEPENS OVER THE HIGH PLAINS. BY LATE FRIDAY AFTERNOON THE FRONT IS EXPECTED TO STRETCH FROM FAR SOUTHWEST WISCONSIN THROUGH SOUTHERN MINNESOTA. THE CLUSTER OF SHOWERS AND STORMS TO WEAKEN AND PUSH NORTHEAST OF THE AREA DURING THE LATE AFTERNOON. HOWEVER...MESOSCALE MODELS....SUCH AS THE ARW...NMM...AND SPC WRF GENERATE SHOWERS AND STORMS ALONG THE FRONT AS IT LIFTS NORTH INTO THE UPPER MISSISSIPPI RIVER VALLEY. 0-3 KM MUCAPE VALUES CLIMB TO 1500 J/KG. GUIDANCE SUGGESTS THAT DEWPOINTS CLIMB INTO HE LOWER 60S RIGHT ALONG AND BEHIND THE WARM FRONT. THIS SEEMS REASONABLE LOOKING AT DEWPOINTS BEHIND THE FRONT THIS AFTERNOON WHERE DEWPOINTS HAVE CLIMBED INTO THE LOWER TO MID 60S. 0-6 KM BULK SHEAR VALUES APPROACH 30 KTS ACROSS NORTHEAST IOWA...SOUTHEAST MINNESOTA AND PORTIONS OF SOUTHWEST WISCONSIN. IF STORMS DEVELOP FRIDAY AFTERNOON NEAR THE WARM FRONT...CANNOT RULE OUT AN ISOLATED SEVERE STORM. THE MAIN HAZARD WOULD BE LARGE HAIL. HIGH TEMPERATURES ON FRIDAY WILL RANGE FROM THE UPPER 50S TO AROUND 60 ACROSS FAR NORTHERN WISCONSIN TO THE MID TO UPPER 70S OVER PORTIONS OF NORTHEAST IOWA. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 343 PM CDT THU MAY 16 2013 THE WARM FRONT IS EXPECTED TO DRIFT NORTHWARD FRIDAY NIGHT THROUGH EARLY SATURDAY MORNING AS A VIGOROUS TROUGH DIGS INTO HE CENTRAL PLAINS. RIDGING DEVELOPS OVER THE UPPER MISSISSIPPI RIVER VALLEY FRIDAY NIGHT INTO SATURDAY MORNING AS MOIST...WARM AIR FLOWS INTO THE FORECAST AREA IN THE WAKE OF THE FRONT. ONCE THE WARM FRONT LIFTS NORTH OF THE AREA AND RIDGING MOVES IN THERE IS VERY LITTLE FORCING TO WORK WITH WITHIN THE WARM SECTOR AND WARMER AIR MOVES IN AT 850 MB...WITH CAPPING HOLDING STRONG THROUGH MUCH OF THE DAY. DECIDED TO INCREASE HIGH TEMPERATURES ACROSS MUCH OF THE FORECAST AREA. WILL HAVE TO KEEP A CLOSE WATCH ON THE CAP AND ANY WEAK FORCING THAT COULD TRIGGER A THUNDERSTORM. IF A SURFACE BASED STORM WOULD DEVELOP IT WOULD HAVE THE POTENTIAL TO PRODUCE LARGE HAIL. THIS LOOKS UNLIKELY AT THIS POINT WITH THE RIDGING OVERHEAD AND THE CAP STRENGTHENING THROUGH THE LATE AFTERNOON HOURS. A VIGOROUS WAVE LIFTS NORTH OUT OF THE CENTRAL PLAINS SUNDAY AFTERNOON AND IS EXPECTED TO MOVE INTO THE UPPER MISSISSIPPI RIVER VALLEY. THUNDERSTORMS ARE EXPECTED TO DEVELOP DURING THE LATE MORNING INTO THE EARLY AFTERNOON HOURS. CAPE AND SHEAR PROFILES WOULD SUPPORT SEVERE THUNDERSTORMS WITH THE POTENTIAL FOR SUPERCELLS. 0-3 KM MUCAPE VALUES INCREASE TO AROUND 1700 J/KG OVER SOUTHEAST MINNESOTA AND NORTHEAST IOWA BY 18Z ON SUNDAY. 0-6 KM BULK SHEAR OF 25 TO 30 KTS...SUNDAY AFTERNOON...INCREASES TO 35 TO 40 KTS LATE IN THE AFTERNOON INTO THE EVENING HOURS AS SURFACE LOW PRESSURE DEEPENS OVER NORTHWEST IOWA/SOUTHEAST SOUTH DAKOTA. 0-1 KM SHEAR ALSO INCREASES TO AROUND 20 KTS LATE SUNDAY AFTERNOON INTO SUNDAY EVENING. THE HIGHEST CHANCES FOR SEVERE THUNDERSTORMS APPEARS TO BE ACROSS SOUTHEAST MINNESOTA AND NORTHEAST IOWA SUNDAY AFTERNOON INTO SUNDAY EVENING. LARGE HAIL...DAMAGING WINDS...AND POSSIBLY AN ISOLATED TORNADO CANNOT BE RULED OUT. ANOTHER ROUND OF STRONG TO POSSIBLY SEVERE THUNDERSTORMS ARE POSSIBLE ON MONDAY INTO MONDAY NIGHT AS THE TROUGH CLOSES INTO A LOW OVER SOUTH DAKOTA AND EMBEDDED WAVES IN SOUTHWEST FLOW ALOFT CONTINUE TO IMPACT THE REGION. THE LOW WILL EDGE EAST TUESDAY THROUGH THURSDAY BRINGING PERIODIC CHANCES FOR SHOWERS AND POSSIBLY THUNDERSTORMS TO THE REGION. HIGHS WILL FALL INTO THE 70S ON TUESDAY THEN INTO THE 60S ON WEDNESDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING) ISSUED AT 613 PM CDT THU MAY 16 2013 COMPLEX OF THUNDERSTORMS HAS DEVELOPED THIS AFTERNOON OVER NORTHWEST IOWA. REGIONAL RADARS SHOWING AN EASTWARD MOVEMENT TO THE STORMS. THIS IS THE AREA MANY OF THE MODELS WERE EXPECTING STORMS TO DEVELOP IN BUT SEVERAL HOURS SOONER THAN EXPECTED. CAPE ANALYSIS SHOWS THE COMPLEX IS CURRENTLY ON THE NORTHERN EDGE OF THE CAPE FIELD WHERE MU CAPES OF 500 J/KG OR GREATER EXTEND FROM ABOUT KSUX TO KMLI. THE 16.21Z RAP SHOWS A SLOW NORTHWARD MOVEMENT OF THIS CAPE FIELD THROUGH THE NIGHT WITH ML CAPES OF 250-500 J/KG COMING TO THE AREA AROUND 09Z. THUS EXPECTING THESE STORMS TO CONTINUE PROGRESSING OFF TO THE EAST/NORTHEAST AND SHOULD START TO APPROACH BOTH TAF SITES BETWEEN 08Z AND 10Z. AS THE SHORT WAVE TROUGH HELPING TO FUEL THE STORMS LIFTS OFF TO THE NORTHEAST...EXPECT THE SHOWERS AND STORMS TO END BY MID MORNING. GENERALLY EXPECTING VFR CONDITIONS WITH THE STORMS ALTHOUGH CAN NOT TOTALLY RULE OUT A PERIOD OF MVFR VISIBILITY IF A HEAVIER SHOWER CAN HIT ONE OF THE AIRPORTS. ONCE THE ACTIVITY MOVES PAST THE REGION FRIDAY MORNING...A MUDDLED PATTERN LOOKS TO BE IN PLACE. THE WARM FRONT WILL STILL BE TO THE SOUTH OF THE AREA AND WITH MOISTURE TRANSPORT INTO THIS...WOULD NOT BE SURPRISED TO SEE SOME AFTERNOON CONVECTION DEVELOP ALONG IT AS HAPPENED ACROSS IOWA TODAY. HOWEVER...NOT SURE HOW MUCH CAPE WILL BE PRESENT AS SKIES COULD REMAIN BROKEN TO OVERCAST WITH CLOUDS FROM TONIGHT/S ACTIVITY. FOR NOW...WILL NOT INCLUDE ANY AFTERNOON CONVECTION AND LET LATER SHIFTS TAKE A CLOSER LOOK AT THIS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...04
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1121 PM MDT TUE MAY 14 2013 .UPDATE... ISSUED AT 738 PM MDT TUE MAY 14 2013 ISOLATED SHOWERS AND THUNDERSTORMS CONTINUE OVER THE NORTHERN NEBRASKA PANHANDLE EARLY THIS EVENING WHILE MOST OF THE SHOWER AND THUNDERSTORM ACTIVITY HAS DIED OFF OVER THE REST OF THE FORECAST AREA. SHOWERS AND THUNDERSTORMS HAVE PRODUCED GUSTY WINDS. TORRINGTON REPORTED A GUST OF 47 KTS WHILE THE ALLIANCE ASOS HIT 49 KTS. THE WIND GUST THREAT WILL QUICKLY SUBSIDE THIS EVENING AS SHOWERS AND THUNDERSTORMS DIE OFF AND MOVE EAST OF THE AREA. && .SHORT TERM...(TONIGHT THROUGH WEDNESDAY NIGHT) ISSUED AT 234 PM MDT TUE MAY 14 2013 WIDESPREAD CUMULUS HAVE DEVELOPED ALONG THE SOUTHERN ZONES THIS AFTERNOON IN A VERY DEEP BOUNDARY LAYER. RADAR IS SHOWING SOME WEAK SHOWERS OUT THERE...HOWEVER ITS PROBABLY MOSTLY VIRGA WITH GUSTY WINDS. THIS ISOLATED SHOWER ACTIVITY WILL LIKELY CONTINUE INTO THE EVENING AS THE RUC SHOWS AROUND 100-200 J/KG OF CAPE THROUGH AROUND 03Z. LAPS ANALYSIS SHOWS A WEAK FRONT LOCATED FROM DOUGLAS TO SIDNEY WITH HIGHER LLVL MOISTURE (DEWPOINTS IN THE 40S) BEHIND IT AND THE MUCH DRIER AIR TO THE SOUTH OF IT. THE MODELS HAVE THIS BOUNDARY PUSHING TO THE SOUTHWEST OVERNIGHT AND STALLING ALONG THE LARAMIE RANGE IN THE MORNING. BOTH THE GFS AND NAM SHOW SOME IMPRESSIVE LLVL MOISTURE BEING ADVECTED IN ON EAST-TO- SOUTHEAST WINDS BY THE MORNING. INCREASED DEWPOINTS INTO THE LOW- TO-MID 40S OVER THE PLAINS OF SOUTHEAST WY FROM WEDNESDAY MORNING THROUGH THE AFTERNOON. THE COMBINATION OF HIGHER LLVL MOISTURE AND SLIGHTLY COOLER MIDLEVEL TEMPS ON WEDNESDAY AFTERNOON WILL RESULT IN GOOD SFC INSTABILITY ALONG AND EAST OF THE LARAMIE RANGE. THE GFS AND NAM BOTH SHOW LIFTED INDICES OF -3C TO -5C WHICH TRANSLATES INTO 1000-1250 J/KG OF CAPE. THE TREND OF THE MODELS HAS BEEN TO INCREASE CONVECTIVE POTENTIAL AND QPF FOR WEDNESDAY AFTERNOON AND EVENING. FOR THIS REASON...UP POPS INTO THE CHANCE CATEGORY OVER THE MTNS AND PLAINS. THE DEEP LAYER SHEAR DOES NOT LOOK IMPRESSIVE OVER THE SOUTHERN ZONES (AROUND 20 KTS)...HOWEVER FURTHER TO THE NORTH ACROSS CONVERSE/NIOBRARA COUNTIES THE MIDLEVEL WINDS ARE STRONGER AND 0-6KM SHEAR APPROACHES 40 KTS. SO IT LOOKS LIKE THAT WILL BE THE REGION TO MONITOR FOR STRONGER STORMS WITH SOME SMALL HAIL POTENTIAL. THE STORMS THAT DEVELOP OVER THE LARAMIE RANGE IN THE EARLY AFTERNOON WILL PROGRESS EASTWARD INTO PORTIONS OF THE WESTERN NEBRASKA PANHANDLE BY THE EARLY EVENING. TEMPS WILL BE AROUND 10 DEGREES COOLER ON WEDNESDAY WITH THE MOIST SE SFC WINDS AND GREATER CLOUD COVER. .LONG TERM...(THURSDAY THROUGH MONDAY) ISSUED AT 234 PM MDT TUE MAY 14 2013 THURSDAY...WEAK SHORTWAVE RIDGING ALOFT. WILL SEE ISOLATED AFTERNOON AND EVENING THUNDERSTORMS...PRIMARILY ORIENTED ALONG THE SURFACE TROUGH AXIS FROM EASTERN WYOMING SOUTHWARD THROUGH EASTERN COLORADO. FRIDAY...FLOW ALOFT BACKS TO SOUTHWEST IN ADVANCE OF NEXT SHORTWAVE TROUGH ALOFT. QUITE WARM WITH A DECENT LOW LEVEL THERMAL RIDGE ORIENTED NORTH TO SOUTH ALONG A DECENT SURFACE TROUGH OVER OUR COUNTIES. ISOLATED AFTERNOON AND EVENING THUNDERSTORMS ALONG A LOW LEVEL CONVERGENCE AXIS FROM CASPER TO CHADRON TO SIDNEY...WITH AREAL COVERAGE OF THUNDERSTORMS MINIMIZED BY WARM TEMPERATURES ALOFT PROVIDING SIGNIFICANT CONVECTIVE INHIBITION...CIN. SATURDAY...DECENT NEGATIVELY TILTED SHORTWAVE TROUGH ALOFT ROTATES EASTWARD ACROSS OUR COUNTIES AND ALONG WITH ITS ASSOCIATED PACIFIC ORIGIN COLD FRONT...EXPECT ISOLATED TO SCATTERED AFTERNOON AND EVENING THUNDERSTORMS...MOST NUMEROUS NEAR THE MOUNTAINS DUE TO DIFFERENTIAL HEATING AND OROGRAPHIC EFFECTS. SUNDAY...A DEFINITE BRITISH ISLES COASTAL FEEL TYPE DAY. BRISK WINDS...COOLER TEMPERATURES AND ISOLATED TO SCATTERED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS ON TAP WITH NORTHWEST FLOW ALOFT AND ENOUGH LOW AND MID LEVEL MOISTURE TO BE LIFTED BY DAYTIME HEATING EFFECTS AND CYCLONIC FLOW ALOFT. LOW LEVEL DOWNSLOPE WINDS WILL PRODUCE A RAIN SHADOW EFFECT FROM WHEATLAND TO CHEYENNE AND MINIMIZE PRECIPITATION COVERAGE. MONDAY...REFRESHINGLY COOL START TO THE TRADITIONAL WORKWEEK IN THE WAKE OF THE RELATIVELY STRONG SHORTWAVE TROUGH PASSAGE AND WITH COOL NORTH WINDS IN USHERING IN RELATIVELY COOL CANADIAN AIR. ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS. TEMPERATURES WILL STILL BE NEAR NORMAL THOUGH. TUESDAY...TRANSITORY SHORTWAVE RIDGE ALOFT MOVES ACROSS OUR COUNTIES AND ALONG WITH MUCH LESS LOW AND MID LEVEL MOISTURE...ONLY ISOLATED AFTERNOON AND EVENING THUNDERSTORMS EXPECTED. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY EVENING) ISSUED AT 1121 PM MDT TUE MAY 14 2013 VFR EXPECTED OVER ALL TERMINALS FOR THE MOST PART DURING THE PERIOD. WIDELY SCATTERED SHOWERS AND A FEW TSTMS EXPECTED TO REFORM WEDS AFTERNOON WITH BRIEF GUSTY WINDS ASSOCIATED WITH SOME OF THEM. ACTIVITY WILL DIMINISH DURING THE EVENING HOURS. && .FIRE WEATHER... ISSUED AT 234 PM MDT TUE MAY 14 2013 RELATIVE HUMIDITY VALUES HAVE DROPPED BELOW 15 PERCENT THIS AFTERNOON ACROSS MUCH OF THE LOWER ELEVATIONS IN A VERY WARM AIRMASS. WINDS HAVE BECOME WEAK NORTHERLY OVER THE PANHANDLE BEHIND A WEAK FRONT...WITH GUSTS GENERALLY BELOW 20 MPH. TEMPERATURES ON WEDNESDAY ARE EXPECTED TO BE AROUND 10 DEGREES COOLER WITH SOUTHEAST WINDS ALONG AND EAST OF THE LARAMIE RANGE. THE INCREASING LOW LEVEL MOISTURE WILL PROMOTE SCATTERED SHOWERS AND THUNDERSTORMS ON WEDNESDAY AFTERNOON AND EVENING. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ UPDATE...LIEBL SHORT TERM...FINCH LONG TERM...RUBIN AVIATION...RUBIN FIRE WEATHER...FINCH
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1257 AM CDT FRI MAY 17 2013 .DISCUSSION... 930 PM CDT THE FORECAST FOR TONIGHT HAS BEEN TWEAKED SLIGHTLY...TO CONTINUE THE EVENING CHANCE OF THUNDER ACROSS THE SOUTHERN FORECAST AREA THROUGH THE NIGHT...AND TO NUDGE IT NORTH SOME. THE EVE WATER VAPOR LOOP DEPICTS THE CLOSED UPPER LOW ACROSS NORTHERN AR EASING ITS WAY NORTHEAST. AT THE SURFACE...THE PRIMARILY SYNOPTIC FRONT IS NEAR THE LOT/ILX CWA BORDER WITH A LAKE BREEZE HAVING PUSHED WELL INLAND. BETWEEN THESE TWO A FEW STORMS GENERATED...IT LOOKED LIKE ON A SLIGHTLY ELEVATED BOUNDARY JUST NORTH OF THE SURFACE BOUNDARY PER ILX RADAR. THESE MAY FESTER NORTHEAST ON THE AFOREMENTIONED MULTIPLE AREAS OF LOW-LEVEL CONVERGENCE FOR SEVERAL MORE HOURS...BUT ANY CG LIGHTNING HAS BEEN SPORADIC AT BEST AND WOULD EXPECT THAT TREND TO CONTINUE OR DIMINISH ALTOGETHER. THE HRRR DOES INDICATE THESE SHOWERS TO SORT OF OSCILLATE ALL THE WAY UP TO FAR NORTHEAST IL THROUGH EARLY OVERNIGHT. THE ILX VAD PROFILER INDICATES INCREASING SOUTHERLY FLOW BELOW 3K FT...NOW UP TO 30 KT. THE LOW-LEVEL JET IS NOT EXPECTED TO INCREASE MUCH FROM THAT MAGNITUDE AND POINT MORE INTO WESTERN IL. MOISTURE TRANSPORT IS MORE LIMITED TONIGHT SO NOT EXPECTING AS MUCH IF ANY ELEVATED CONVECTION...BUT COULD SEE SOME IN WESTERN IL WHERE A LITTLE MORE THETA-E ADVECTION AND CONVERGENCE AROUND 850MB IS FORECAST. THE LAKE BREEZE MADE IMPRESSIVE PROGRESS WSW THROUGH EARLY EVE AFTER SORT OF A SLOW START. A 30 DEGREE SPREAD AS OF 930 PM EXISTS ACROSS THE CWA SIMPLY FROM JUST THIS MESOSCALE BOUNDARY. HAVE ADJUSTED THE HOURLY TEMPERATURE FORECAST TO MEET TRENDS. THE LAV GUIDANCE HAS VERY LITTLE TEMPERATURE DROP FOR MANY POINTS THROUGH THE REST OF THE NIGHT...LIKELY DUE TO INCREASING CLOUD COVER. WHILE CAA OFF THE LAKE LIKELY WILL CREATE A LITTLE MORE DROP THAN IT ADVERTISES...THIS IS IN LINE WITH THE GOING MINIMUM TEMPERATURE FORECASTS. MTF //PREV DISCUSSION... 259 PM CDT TODAY`S FORECAST CHALLENGES CONTINUE TO BE DEALING WITH FRONTAL BOUNDARY CURRENTLY JUST SOUTH OF THE CWA...AND PERIODIC CONVECTIVE CHANCES THROUGH MID NEXT WEEK. TODAY AND TONIGHT... THIS AFTERNOON THE FRONT IS LOCATED JUST NORTH OF QUINCY IL EAST TO NEAR TERRE HAUTE INDIANA...AND HAS BEEN SLOWLY PUSHING NORTH THIS AFTERNOON. MODERATE INSTABILITY EXISTS SOUTH OF THE FRONT AND MAY LIFT INTO FAR SOUTHERN PORTIONS OF THE CWA LATE THIS EVENING BEFORE FADING NOCTURNALLY. MAINTAINED SLT CHC POPS FOR A FEW HOURS THIS EVENING WHEN THIS OCCURS...BUT OTHERWISE SHOULD BE FAIRLY QUIET PERIOD THROUGH TONIGHT. FRIDAY THROUGH SATURDAY... COMPACT SHORTWAVE NOTED ON WV IMAGERY THIS AFTERNOON OVER WESTERN NE/KS WILL CONTINUE ENE INTO WEST CENTRAL WISCONSIN BY FRIDAY AFTERNOON. AS THIS HAPPENS...SOUTHERLY FLOW INCREASE AT THE SURFACE AND SHOULD HELP PUSH THE BOUNDARY NORTH ACROSS THE AREA. DEWPOINTS RISE INTO THE MID 60S AND MODEST INSTABILITY DEVELOPS OUTSIDE OF FAR NE ILLINOIS WHERE ONSHORE WINDS WILL KEEP CONDITIONS COOLER/MORE STABLE. THIS INSTABILITY IS UNCAPPED...AND GIVEN THERE IS NO WELL DEFINED FOCUS FOR THUNDERSTORMS...EXPECT UNORGANIZED/SCATTERED CONVECTION TO DEVELOP WITHIN THE WARM SECTOR. MID LEVEL LAPSE RATES ARE PRETTY POOR...SO CONVECTION MAY STRUGGLE AT TIMES AND MAY LIMIT THE THUNDER CHANCES TO SOME DEGREE. MUCH OF THE SAME IS EXPECTED SATURDAY SO WILL MAINTAIN THE LOW POPS FOR DIURNALLY DRIVEN TSTORMS. SUNDAY THROUGH TUESDAY... THIS PERIOD CONTINUES TO LOOK ACTIVE AS THE OVERALL PATTERN AMPLIFIES WITH DEEP TROUGHING DEVELOPING ACROSS THE WESTERN CONUS...AND STRONG RIDGING EAST. THE H85 THERMAL RIDGE BEGINS TO WORK INTO THE AREA SUNDAY...AS WELL AS DRY AIR ALOFT AND THE EML LATER IN THE DAY HELPING TO STEEPEN LAPSE RATES ALOFT. NEGATIVELY TILTED TROUGH IS EXPECTED TO ROUND THE BASE OF THE LONGWAVE TROUGH SUNDAY LIFTING INTO THE MID MISSOURI VALLEY SUNDAY NIGHT. MODELS ARE MIXED ON WHETHER OR NOT THE CIN ERODES DURING THE DAYTIME...BUT IF IT DOES CHANCES WILL BE BEST OVER WESTERN PORTIONS OF THE CWA...SO HAVE MAINTAINED LOWER POPS. THERE MAY BE A BETTER CHANCE FOR CONVECTION OVERNIGHT AS A LOW LEVEL JET DEVELOPS JUST TO OUR WEST WITH LARGE SCALE ASCENT ASSOCIATED WITH AFOREMENTIONED TROUGH. ON MONDAY...THE GFS INDICATES ANOTHER LOWER AMPLITUDE DISTURBANCE WILL ROUND THE BASE OF THE LONGWAVE TROUGH AND LIFT INTO THE MID MISSISSIPPI VALLEY. THIS CONTINUES TO BE A DAY TO KEEP AN EYE ON FOR SEVERE WEATHER POTENTIAL. MODELS CONTINUE TO ADVERTISE MODERATE TO STRONG INSTABILITY IN PLACE OVERHEAD WITH MARGINAL SHEAR CONDITIONS TO SUPPORT SEVERE WEATHER. AS PREVIOUSLY MENTIONED...CONVECTION FROM THE PREVIOUS NIGHT...CLOUD COVER...AND OTHER SMALL SCALE FEATURES CANNOT BE RESOLVED THIS FAR OUT AND ADD A CONSIDERABLE AMOUNT OF UNCERTAINTY. WE SHOULD BEGIN TO GET A BETTER PICTURE THIS WEEKEND SO STAY TUNED FOR FORECAST UPDATES. DEPENDING ON THE SPEED OF THE SYSTEM...TUESDAY WILL ALSO HAVE TO BE MONITORED...PERHAPS WITH THE THREAT MORE FOCUSED ON THE EASTERN PORTIONS OF THE CWA. IN ADDITION TO THE SEVERE THREAT...MULTIPLE ROUNDS OF THUNDERSTORMS MOVING ALONG THE SLOW MOVING BOUNDARY SUNDAY NIGHT THROUGH TUESDAY WILL LEAD TO A INCREASED HEAVY RAIN AND FLOODING THREAT. FOR TEMPERATURES SUNDAY AND MONDAY...CONTINUE TO LEAN ON THE WARMER BIAS CORRECTED GEM WHICH HAPPENED TO VERIFY BEST WITH THE UNSEASONABLY HEAT TUESDAY. DEPENDING ON THE SPEED OF THE SYSTEM...CURRENT FORECAST TEMPS MAY BE A BIT ON THE COOL SIDE TUESDAY...PARTICULARLY THE EASTERN CWA. H85 TEMPS OF 16-18C AND H92 TEMPS OF 19-22C SHOULD SUPPORT TEMPERATURES WELL INTO THE 80S AND WOULDN`T BE SURPRISED TO SEE PLACES HIT 90S THOSE DAYS...BUT WILL REMAIN A BIT CONSERVATIVE GIVEN THE PRECIP CHANCES AND CLOUD COVER. DEUBELBEISS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * ISOLATED SHOWER REMAIN SOUTHWEST OF TERMINALS THRU MID-MORNING. * PRECIP COVERAGE INCREASES BY MIDDAY...POSSIBLE THUNDERSTORM ARND 19-22Z. * WINDS REMAIN EASTERLY WITH SPEEDS GENERALLY ARND 10KT OR LESS...TURNING SOUTHEASTERLY AFT 05Z SAT. * CIGS REMAIN VFR...POSSIBLE MVFR CIGS IN OR AROUND TSRA/SHRA. BEACHLER //DISCUSSION...UPDATED 06Z... IR IMAGERY EARLY THIS MORNING SHOWS AN AREA OF CLOUDS ACROSS THE WESTERN GREAT LAKES INTO THE UPPER MIDWEST. SCT SHOWERS/THUNDERSTORMS ACROSS NORTHCENTRAL IOWA/SOUTHCENTRAL MINNESOTA. THIS PRECIPITATION WAS LOCATED ALONG A STALLED FRONTAL BOUNDARY THAT STRETCHES EAST/SOUTHEAST INTO CENTRAL IL/IN. AIRFIELDS ACROSS NORTHERN IL/NORTHWEST IN REMAIN VFR...WITH SOME CLOUDS OBSERVED AT 8KFT AGL OR HIGHER. GUIDANCE CONTINUE TO SUGGEST VFR CONDS WILL CONTINUE THROUGH DAYBREAK...WITH A CONTINUED LIGHT EAST WIND ARND 8KT OR LESS. THE DIRECTION WILL GENERALLY REMAIN BETWEEN A 060-090 DEG RANGE...HOWEVER SOME VRB DIRECTIONS MAY OCCUR THRU DAYBREAK AS SPEEDS WILL BE LESS THAN 5 KT. THEN IT APPEARS THE BEST CHC FOR PRECIP WILL OCCUR SOUTHWEST OF THE TAF SITES THRU MUCH OF THE MORNING...WITH MINIMAL COVERAGE. BY MIDDAY COVERAGE SHUD BEGIN TO INCREASE IN SHOWERS/THUNDERSTORMS...AND GUIDANCE IS BEGINNING TO SHOW A HIGHER CONFIDENCE IN TIMING OF 18-22Z. HAVE OPTED TO PLACE A VCSH TO HANDLE THE BEGINNING COVERAGE AT 16Z...WITH A TEMPO IN A 19-22Z TIMEFRAME. THIS APPEARS TO BE THE BEST TIME THAT A THUNDERSTORM WOULD OCCUR. THEN IT APPEARS ANY PRECIP WILL PUSH BACK TO THE WEST/SOUTHWEST OF THE AIRFIELDS...WITH A SMALL CHC OF PRECIP CONTINUEING THROUGH THE EVENING HOURS. WINDS WILL EVENTUALLY BEGIN TO TURN SOUTHEASTERLY ONCE THE BOUNDARY LIFTS OVERHEAD AND TO THE NORTH OF THE TAF SITES...HOWEVER THIS DOES NOT APPEAR TO OCCUR UNTIL AFT 05Z SAT. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 06Z... * HIGH CONFIDENCE IN WIND DIR/SPEED. * MEDIUM CONFIDENCE IN CIGS FORECAST. * LOW CONFIDENCE IN PRECIP TIMING/COVERAGE. * MEDIUM CONFIDENCE IN THUNDERSTORMS. * MEDIUM/HIGH CONFIDENCE IN WIND DIRECTION BECOMING SOUTHEAST TIMING. BEACHLER //OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z... SATURDAY THROUGH WEDNESDAY...PERIODIC CHANCES FOR SHRA/TSRA... OTHERWISE...VFR. KREIN && .MARINE... 228 PM CDT RIDGING FROM HIGH PRESSURE CENTERED OVER WESTERN ONTARIO EXTENDS ACROSS LAKE MICHIGAN THIS AFTERNOON. WEAK LOW PRESSURE WILL DEVELOP AND MOVE UP THE OHIO RIVER VALLEY FRIDAY WITH ADDITIONAL LOW PRESSURE DEVELOPING ACROSS THE CENTRAL HIGH PLAINS. EAST TO NORTHEAST FLOW OVERALL WILL CONTINUE ACROSS THE LAKE...WITH ONSHORE FLOW IN AREAS WHERE THE PRESSURE GRADIENT IS WEAKER CAUSING SOME ERRATIC DIRECTIONS AT TIMES. STEADIER AND MORE UNIFORM WINDS WILL DEVELOP WITH TIME THROUGH TOMORROW WITH MORE OF AN EAST TO SOUTHEAST TREND. THE STRONGEST WINDS WILL OCCUR FRIDAY EVENING/NIGHT COINCIDENT WITH THE STRONGEST PRESSURE GRADIENT THANKS TO THE LOW PASSING TO THE SOUTHEAST. THE GRADIENT WEAKENS DURING THE DAY SATURDAY AS THE LOW DEPARTS TO THE EAST. LOW PRESSURE STRENGTHENS ACROSS THE CENTRAL/NORTHERN HIGH PLAINS INTO SUNDAY WHICH WILL GRADUALLY TIGHTEN THE PRESSURE GRADIENT ACROSS THE LAKE. THIS WILL ALLOW A STEADY SOUTH TO SOUTHEAST WIND TO DEVELOP ACROSS MOST OF THE LAKE...WITH A MORE EASTERLY DIRECTION ACROSS THE FAR NORTH WHERE A WARM FRONTAL BOUNDARY IS EXPECTED TO SET UP. THE MAIN LOW WILL MEANDER NORTHWARD BEFORE BEING PUSHED EASTWARD ACROSS MINNESOTA/IOWA SOMETIME TUESDAY OR WEDNESDAY WHICH WILL LIKELY PUSH THE FRONTAL BOUNDARY FURTHER SOUTH ACROSS THE LAKE LEADING TO EAST TO NORTHEAST WINDS NORTH AND SOUTH TO SOUTHWEST WINDS SOUTH BY MID WEEK. THE MAIN CONCERN WILL BE THE POTENTIAL FOR INCREASED GUSTINESS ACROSS THE NORTH AS COLDER AIR SETTLES IN ALLOWING SLIGHTLY INCREASED MIXING. OTHERWISE...GENERALLY STABLE LOW LEVEL AIR ACROSS THE LAKE WILL KEEP GUSTS TO A MINIMUM FROM TONIGHT THROUGH THE WEEKEND. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1154 PM CDT THU MAY 16 2013 .DISCUSSION... ISSUED 743 PM CDT THU MAY 16 2013 SYNOPTIC FRONTAL BOUNDARY HAS LIFTED NORTHWARD TO NEAR THE I-74 CORRIDOR EARLY THIS EVENING. DEWPOINTS TO THE SOUTH OF THE BOUNDARY ARE IN THE UPPER 50S AND LOWER 60S ACROSS MUCH OF THE KILX CWA...WHILE DEWPOINTS NORTH OF THE FRONT ARE ONLY IN THE 40S ACROSS NORTHERN ILLINOIS. MESOSCALE OUTFLOW BOUNDARY FROM CONVECTION EARLIER TODAY FROM NEAR SPRINGFIELD S/SE TO LAWRENCEVILLE HAS LIFTED NORTHWARD AS WELL...RESULTING IN A RELATIVELY STABLE AIRMASS ACROSS THE AREA. BEST INSTABILITY AND LIFT IS CURRENTLY FOCUSED ALONG/NORTH OF THE FRONTAL BOUNDARY ACROSS THE FAR NORTHERN CWA. A FEW SHOWERS HAVE DEVELOPED ACROSS WOODFORD AND NORTHERN MCLEAN COUNTIES OVER THE PAST HOUR...AND THIS AREA WILL HAVE TO BE MONITORED FOR ADDITIONAL DEVELOPMENT AS THE EVENING PROGRESSES. WILL MAINTAIN SLIGHT CHANCE POPS EVERYWHERE DURING THE EVENING...THEN WILL LIMIT POPS TO ONLY THE NORTHERN CWA IN CLOSER PROXIMITY TO THE FRONT OVERNIGHT. ZONE UPDATE HAS ALREADY BEEN SENT. && .AVIATION... ISSUED 1154 PM CDT THU MAY 16 2013 04Z/11PM RADAR IMAGERY SHOWS DRY CONDITIONS ACROSS MUCH OF CENTRAL ILLINOIS...WITH ONE CLUSTER OF PERSISTENT SHOWERS/THUNDER BETWEEN KVYS AND KPNT. STATIONARY FRONTAL BOUNDARY JUST NORTH OF THE I-74 CORRIDOR WILL CONTINUE TO TRIGGER ISOLATED CONVECTION OVERNIGHT...HOWEVER IT IS EXPECTED TO REMAIN NORTH OF THE KILX TERMINALS. UPPER LOW CURRENTLY SPINNING OVER THE OZARKS WILL LIFT NORTHEASTWARD INTO THE OHIO RIVER VALLEY ON FRIDAY. DEEPER MOISTURE ARRIVING WITH THIS FEATURE WILL LEAD TO SCATTERED SHOWERS AND THUNDERSTORMS THROUGHOUT THE DAY INTO THE EARLY EVENING. BASED ON NAM TIMING...HAVE INTRODUCED VCTS AT KSPI AND KDEC BY 13Z...THEN FURTHER NORTH TO KPIA BY 16Z. AS LOW SHIFTS FURTHER EAST AND DAYTIME INSTABILITY IS LOST...CONVECTION WILL DISSIPATE AFTER 02Z. WINDS WILL BE LIGHT AND SOUTHERLY OVERNIGHT...THEN WILL BACK TO E/SE ON FRIDAY. BARNES && .PREV DISCUSSION... ISSUED 300 PM CDT THU MAY 16 2013 A STATIONARY FRONT WILL OSCILLATE NORTH AND SOUTH ACROSS ILLINOIS OVER THE NEXT DAY AND A HALF...THEN THE FRONT SHOULD LIFT NORTH AS A WARM FRONT FOR THE WEEKEND...PUSHING HIGHS INTO THE MID TO UPPER 80S BY SUNDAY. BANDS OF THUNDERSTORMS THAT DEVELOP THROUGH TOMORROW WILL LIKELY BE SLOW MOVING, HEAVY RAIN PRODUCERS LIKE TODAY`S STORMS. LOCALIZED AREAS COULD SEE SIGNIFICANT RAINFALL OF 2-3 INCHES IN A COUPLE HOURS WHILE NEARBY AREAS SEE LITTLE RAIN. PINPOINTING THAT ACTIVITY WILL BE DIFFICULT...BUT DIURNAL TRENDS SHOULD PUT MOST OF THE CONVECTION DURING THE AFTERNOON TOMORROW...ESPECIALLY NEAR ANY OUTFLOW BOUNDARIES SET DOWN BY TODAY`S STORMS. A SLIGHT LULL IN STORMS SHOULD OCCUR THIS WEEKEND AS RIDGING IN THE PLAINS BUILDS INTO IL. A STRONGER COLD FRONT IS EXPECTED TO PUSH ACROSS IL ON MONDAY AND MONDAY NIGHT...BRINGING OUR BETTER CHANCES OF THUNDERSTORMS. WE ARE IN THE SPC DAY 5 OUTLOOK FOR STRONG TO SEVERE STORMS MON-MON NIGHT. A COOL DOWN IS PROJECTED FOR TUES THROUGH THURSDAY BEHIND THE COLD FRONT...PULLING HIGHS BACK INTO THE 70S...BUT STILL AT OR ABOVE NORMAL. SHORT TERM...TONIGHT THROUGH SUNDAY. SHOWERS AND STORMS WILL GENERALLY BE DIMINISHING AS WE HEAD INTO THE EVENING. THE LINE OF CONVECTION MAINLY CENTERED ON A LINE FROM RUSHVILLE TO TAYLORVILLE TO EFFINGHAM TO LAWRENCEVILLE...IS EXPECTED TO LIFT NORTH THIS EVENING. THE RAP MODEL IS SHOWING THE INSTABILITY AXIS FOLLOWING THE SAME PROGRESSION...WITH SOME SHOWER ACTIVITY DEVELOPING DURING THAT TIME. IN THE LAST HOUR...PRECIP COVERAGE AND UPDRAFT INTENSITY HAVE ALREADY BEGUN DIMINISHING OR WEAKENING RESPECTIVELY. RADAR LOOPS SHOW VARIOUS OUTFLOW BOUNDARIES MOVING NORTH ACROSS OUR COUNTIES...AND MAY END UP BEING A FOCUS FOR EVENING SHOWERS ALONG AND NORTH OF I-72. STILL...COVERAGE WILL BE ISOLATED IN GENERAL. FRIDAY MORNING...THE LOCATION OF THE BEST INSTABILITY WILL BE ALONG AND NORTH OF I-74...SO ANY MORNING CONVECTION ON FRIDAY MAY BE FOCUSED IN THAT AREA. DURING THE AFTERNOON...AN UPPER LOW PRESSURE WAVE IS FORECAST TO LIFT NORTHEAST ACROSS IL...IN CONCERT WITH INCREASING MOISTURE AND INSTABILITY AS THE STATIONARY FRONT OSCILLATES NORTHWARD WITH THE WAVE. COVERAGE OF STORMS SHOULD BE MORE THAN TODAY...BASED ON THE SUPPORT OF THE UPPER WAVE AND JET DYNAMICS. ANY SUNSHINE THAT HEATS UP THE BOUNDARY LAYER WILL HELP TO CREATE A FEW STRONG UPDRAFTS WITH SMALL HAIL, GUSTY WINDS, AND VERY HEAVY RAINFALL. THE STORMS MAY LINGER INTO THE EVENING EAST OF I-57...BUT SHOULD DIMINISH BY MIDNIGHT. BY 12Z SAT MORNING...THE UPPER LOW IS FORECAST TO BE CENTERED IN SOUTHERN INDIANA...WHICH WILL HELP PUT PRECIP CHANCES MAINLY IN OUR SOUTHEAST COUNTIES ALONG AND SOUTHEAST OF A LINE FROM SHELBYVILLE TO PARIS. THE SLOW DEPARTURE OF THE LOW WILL KEEP CHANCES OF SHOWERS AND STORMS THROUGH SATURDAY AFTERNOON IN THE SOUTHEAST. THE WARM FRONT DEPARTING INTO NORTHERN IL FOLLOWED BY RIDGING AT THE SURFACE AND ALOFT SATURDAY NIGHT AND SUNDAY SHOULD HELP MAKE MOST AREAS DRY FOR THE LAST HALF OF THE WEEKEND. THE ADDITIONAL SUNSHINE ON SUNDAY ALONG WITH DEEPER WARM AIR WILL HELP PUSH HIGH TEMPS INTO THE MID TO UPPER 80S...WITH MUGGY DEWPOINTS IN THE UPPER 60S TO NEAR 70. HEAT INDEX READINGS SUNDAY AFTERNOON WILL CLIMB INTO THE 90S. LONG TERM...MONDAY THROUGH THURSDAY. ON MONDAY...AN OCCLUDING LOW PRESSURE PRESSURE SYSTEM IN THE EASTERN DAKOTAS WILL CREATE SOME WARM FRONTOGENESIS TO THE SOUTHEAST OF THE LOW ACROSS OUR NORTHERN COUNTIES. THAT WILL CREATE A FOCUS FOR CONVECTION BY MONDAY AFTERNOON. MONDAY NIGHT...A COLD FRONT WILL MOVE ACROSS IL PRODUCING STRONG TO SEVERE STORMS AS ML-CAPE VALUES CLIMB TO NEAR 2K J/KG. BULK SHEAR IS EXPECTED TO REACH OVER 40KT AS WELL...SO EMBEDDED SUPERCELLS WILL BE POSSIBLE IN THE LINE OF STORMS THAT MOVES THROUGH. STORMS ARE EXPECTED TO LINGER INTO TUESDAY AS THE UPPER COLD POOL SLOWLY MAKES PROGRESS INTO ILLINOIS. WE KEPT LIKELY POPS SOUTHEAST OF I-72...AND CHANCE ELSEWHERE. TUESDAY NIGHT PRECIP COVERAGE SHOULD DIMINISH...WITH CHANCE POPS STILL IN PLACE ACROSS THE BOARD. AN ELONGATED SURFACE TROUGH IS PROJECTED TO LINGER ACROSS NORTHERN ILLINOIS INTO WED AS THE OCCLUDED UPPER LOW BECOMES MORE OF AN OPEN WAVE AND SEND A SURFACE LOW EASTWARD ACROSS WISCONSIN. THAT PROGRESSION WILL KEEP SCATTERED SHOWERS POSSIBLE AS FAR SOUTH AS CENTRAL ILLINOIS THROUGH THURSDAY...ESPECIALLY EAST OF I-55. PRECIP AMOUNTS MID WEEK SHOULD REMAIN LIGHT...BUT STILL CLOUDS AND COOLER AIR WILL KEEP HIGH TEMPS BACK IN THE 70S...CLOSER TO NORMAL. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
224 AM EDT FRI MAY 17 2013 .SYNOPSIS... ISSUED AT 205 AM EDT FRI MAY 17 2013 A STATIONARY FRONT WILL REMAIN OVER THE AREA WITH A CHANCE FOR SHOWERS AND THUNDERSTORMS IN THE VICINITY OF THE FRONT AND SOUTH OF THE FRONT. SHOWER AND THUNDERSTORM CHANCES WILL PERSIST THROUGH THE WEEKEND AS THE FRONT REMAINS ACROSS THE AREA. ABOVE NORMAL TEMPERATURES ARE EXPECTED THIS WEEKEND. CHANCES FOR SHOWERS AND THUNDERSTORMS INCREASE EARLY NEXT WEEK AS A STORM SYSTEM APPROACHES FROM THE WEST. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) HIGH PRESSURE HAS KEPT BULK OF MSTR JUST FAR ENOUGH SOUTH OF THE AREA TODAY TO ALLOW FOR GENERALLY DRY CONDITIONS AND TEMPS MOVING WELL THROUGH THE 70S IN MOST SPOTS. A FEW LIGHT SHOWERS/SPRINKLES WERE NOTED ALONG FIRST OF 2 SFC THETA E GRADIENTS ACROSS FAR SOUTHERN COUNTIES. THIS AREA IS EXPECTED TO SHIFT SOUTH OVER THE NEXT SEVERAL HOURS AND REMOVE ANY CHANCE FOR PRECIP FOR THE REMAINDER OF THE NIGHT. SECONDARY GRADIENT WAS LOCATED FURTHER SOUTH ACROSS SOUTHERN INDIANA WHERE CONVECTION HAS BEEN ONGOING MUCH OF THE DAY. MODELS TEND TO SUGGEST THAT THIS SECONDARY AREA OF MSTR/GREATER LIFT SUPPORT WITH MAIN SFC BOUNDARY WILL BRING INCREASING CHANCES FOR SHOWERS AND STORMS ON FRIDAY. IT WOULD APPEAR THAT MOST FAVORABLE TIMING WOULD BE MID TO LATE AFTERNOON FRIDAY IN FAR SW SECTIONS WITH PROGRESSION NE HAMPERED SOMEWHAT BY DRY AIR/SEMI DRY GROUND CONDITIONS. IF NEW RUN OF SPC 4KM WRF IS FOLLOWED...CONVECTION WOULD NOT ARRIVE UNTIL AFTER 00Z SAT. HAVE ADJUSTED GRIDS TO REFLECT THIS WITH SLGT CHC TO CHC POPS CONFINED TO AFTERNOON. CLOUD COVER WILL BE ON THE INCREASE...WHICH WILL BUT A DAMPER ON POTENTIAL CLIMB IN HIGHS. THAT BEING SAID...HIGHS SHOULD STILL END UP ABOVE NORMAL CLIMBING INTO THE MID AND UPPER 70S. && .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) WATER VAPOR IMAGERY AND LATEST RAP ANALYSIS THAT IS DEPICTING MID LEVEL CIRCULATION MOVING EASTWARD ACROSS THE SOUTHERN PLAINS THIS AFTERNOON WILL HAVE AN IMPACT ON THE BEGINNING OF THE EXTENDED FCST PERIOD AS IT MOVES ACROSS THE TN VALLEY. THIS WILL ACT ON STATIONARY SFC BOUNDARY IN ADVECTING MOISTURE IN AN OVERRUNNING FASHION BACK NORTH OF THE BOUNDARY AND LEND SUPPORT TO WIDELY SCATTERED CONVECTION OVER THE SW HALF OF THE CWA. FOCUS WILL THEN SHIFT TO AMPLIFICATION OF THE UPPER LEVEL PATTERN AS STRONG JET DYNAMICS CURRENTLY WELL OUT IN THE PACIFIC ARE PROGGED BY MEDIUM RANGE MODELS TO COME ONSHORE AND DEVELOP DEEP UPPER TROF OVER THE WESTERN US. THIS WILL INDUCE DOWNSTREAM RIDGING THAT WILL BUILD INTO THE REGION SUN/MON BRINGING WARMER AND MAINLY DRY CONDITIONS TO THE AREA. WESTERN CONUS UPPER TROF THEN EXPECTED TO BECOME VERTICALLY STACKED CLOSED SYSTEM IN THE NORTHERN PLAINS WHICH MODELS ARE STRUGGLING WITH TIMING OF THE EVENTUAL EJECTION OF THIS SYSTEM INTO OUR AREA. AS EXPECTED OVERALL TREND CONTINUES TO BE SLOWER WITH ARRIVAL OF MAIN SYSTEM NOW DELAYED TO TUE/WED TIMEFRAME AND BRINGING WITH IT THE BEST CHANCES FOR PRECIP. PRIOR TO ITS ARRIVAL...BECOMING MORE AND MORE DIFFICULT TO PICK OUT MODELS HANDLING OF INCREASINGLY DIFFUSE SFC BOUNDARY BUT INDICATIONS ARE BOUNDARY WILL LIFT NORTH OF THE AREA IN CONJUNCTION WITH UPPER RIDGE MOVING OVER THE AREA WHICH SHOULD LEAVE MUCH OF THE FORECAST AREA IN A CAPPED WARM SECTOR SUN/MON. LOW CONFIDENCE IN ANY ONE PARTICULAR SCENARIO WITH THIS SETUP BUT WILL STILL INJECT A PERIOD OR TWO OF DRY WEATHER TO REFLECT THIS. ANTICIPATE TEMPS WELL INTO THE 80S ON MONDAY DEPENDING ON AMOUNT OF SUN...BUMPED ALLBLEND UP A DEGREE TO START UPWARD TREND. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 205 AM EDT FRI MAY 17 2013 A WELL DEFINED FRONT WAS JUST SOUTHWEST OF THE TERMINALS EARLY THIS MORNING. THE FRONT SHOULD BE NEARLY STATIONARY TODAY...BUT MAY DRIFT NORTH AS A WARM FRONT LATER TODAY. ADDED A VICINITY SHOWER AT BOTH TERMINALS LATE IN THE DAY WITH THE FRONT IN THE VICINITY AND DURING MAXIMUM DAYTIME INSTABILITY. THERE IS ALSO AN OUTSIDE CHANCE FOR THUNDER...MAINLY LATE AFTERNOON INTO EARLY EVENING...BUT FOR NOW...LEFT THUNDER OUT GIVEN THE MORE ISOLATED NATURE OF COVERAGE EXPECTED. KEPT TAFS VFR. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...BENTLEY SHORT TERM...FISHER LONG TERM...JAL AVIATION...SKIPPER VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
341 AM EDT FRI MAY 17 2013 .SYNOPSIS... A FRONTAL BOUNDARY WILL STALL OUT TO THE SOUTH THROUGH THIS WEEKEND...AS HIGH PRESSURE ANCHORS ITSELF ACROSS THE NORTH ATLANTIC. THE FRONTAL BOUNDARY WILL RETURN TO THE NORTH AS A WARM FRONT EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... A WEAK PSEUDO-STATIONARY FRONTAL BOUNDARY HAS FINALLY DRIFTED SOUTH OF THE MASON-DIXON LINE AND IS HELPING TO CLEAR OUT THE AREA OVERNIGHT. THIS BOUNDARY CONTINUES TO STRETCH FROM THE ATLC COAST...DIRECTLY WEST TO THE PLAINS. NOW W/ THE BOUNDARY SET-UP OVER THE REGION AND NO DISCERNIBLE SYSTEMS COMING DOWN THE PIKE IN THE NEXT COUPLE OF DAYS...IT WILL RESIDE JUST SOUTH OF THE AREA AND BE THE FOCUS FOR DAILY WEAKLY-FORCED CONVECTION DEPENDING ON WHERE IT IS LOCATED. PRECIP ALONG THIS BOUNDARY AS ALL BUT ENDED OVER THE PAST FEW HRS AND CONDITIONS WILL BE STABLE UNTIL DAWN. LOCALIZED HRRR CONTINUES TO DEVELOP TERRAIN CONVECTION LATER TODAY. ISOLATED SHOWERS AND TSTMS WILL LIKELY DEVELOP THIS AFTN/EVE FROM A LIGHT ESE FLOW BANKING INTO THE ERN SIDES OF THE HIGHEST TERRAIN OF THE CENTRAL APPALACHIANS...TAPERING OFF TOWARD THE SHEN VLY. STEERING FLOW WILL BE INCREDIBLY LIGHT...A MEAN 10-15KT FLOW ALL THE WAY UP TO THE UPPER LEVELS...WON`T TAKE MUCH OF THIS ACTIVITY EWD. WEAK OUTFLOW BOUNDARIES WILL HAVE TO DO THAT IN ORDER TO SPREAD POPS MUCH FURTHER EAST. CUT BACK ON POPS OVERNIGHT FOR THE ERN HALF OF THE REGION. DEPICTIONS FROM THE NAM/GFS FOR A LOCALIZED BATCH OF PRECIP STREAMING ACROSS A BULK OF THE CWA DURING THE PREDAWN HRS SAT STILL A BIT SUSPECT. PLACEMENT OF SUCH A SMALL-SCALE UPPER WAVE CAUGHT IN THE FLOW STILL A BIT TOO FAR OUT TO PLACE IN THE CURRENT FORECAST. TEMPS TODAY WILL BE EVEN MORE MODERATED TODAY FROM YESTERDAY W/ DRIER AIR AND A LIGHT BUT STEADY NE BREEZE COMING DOWN THE I-95 CORRIDOR FOR MUCH OF THE DAY. MOST AREAS WILL PEAK IN THE U70S...W/ A FEW LOCALES HITTING 80 LATE THIS AFTN. OVERNIGHT LOWS WILL BE SIMILAR TO THE CURRENT OVERNIGHT PERIOD...TEMPS DROPPING INTO THE U50S/L60S. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... FRONTAL BOUNDARY WILL REMAIN STALLED OUT TO THE SOUTH THIS WEEKEND...AS HIGH PRESSURE ANCHORS ITSELF OFF THE NORTHEAST COAST AND NORTH ATLANTIC. RESULT WILL BE AN EAST OR SOUTHEAST FLOW IN THE LOW LEVELS WHICH WILL PROMOTE CLOUDY SKIES MUCH OF THE TIME AND ALSO TEMPER WARMING. THE DEGREE TO WHICH WARMING IS TEMPERED DIFFERS BETWEEN THE NAM AND GFS DERIVED MOS GUIDANCE...WITH THE GFS BEING LOWER BY 10 DEGREES IN SOME CASES FOR MAXIMA. DIFFERENCES ARE LIKELY EXPLAINED BY THE PRESENCE OF PRECIPITATION OR LACK THEREOF. THE GFS IS MUCH MORE AGGRESSIVE BRINGING MEASURABLE RAINFALL ACROSS THE CWA WHILE THE NAM IS MORE CONSERVATIVE. SREFS FORMS A NICE COMPROMISE...FOCUSING SHOWERS /AND PERHAPS A FEW THUNDERSTORMS/ ACROSS THE SOUTHWEST PORTION OF THE CWA SATURDAY AND THEN SPREADING CHANCES /OR LIKELIHOODS/ FOR RAINFALL NORTHEAST INTO SUNDAY. MOISTURE IS CERTAINLY THERE...WHETHER ISENTROPIC LIFT WORKS THIS FAR NORTH AND WHETHER THERE ARE SHORTWAVES IN 500 MB FLOW IS SOMEWHAT IN QUESTION. FOR TEMPERATURES...HAVE TAKEN A BLEND OF BIAS CORRECTED MAV/MET AND ALSO ECMWF WHICH FAVORS LOWER 70S ACROSS MUCH OF THE AREA FOR MAXIMA. NO MATTER HOW ONE SLICES IT...MAXIMA OVER THE WEEKEND WILL LIKELY BE BELOW NORMAL WITH NEAR TO SLIGHTLY ABOVE NORMAL MINIMA. && .LONG TERM /MONDAY THROUGH THURSDAY/... FRONTAL BOUNDARY WILL LIFT BACK TO THE NORTH AS WARM FRONT EARLY NEXT WEEK...MOST LIKELY LATE MONDAY INTO EARLY TUESDAY AND PLACING THE CWA IN A WARM SECTOR DURING THE MIDDLE OF THE WEEK. THIS SHOULD BRING LOW LEVEL SOUTH-SOUTHWEST FLOW WHICH WILL KEEP MOISTURE ACROSS THE AREA AND SOME SURFACE-BASED INSTABILITY. THEREFORE FORECAST REFLECTS A CHANCE OF MAINLY DIURNAL CONVECTION EACH DAY. FRONTAL BOUNDARY MAY APPROACH ON THURSDAY. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... A WEAK FRONTAL BOUNDARY SINKING SWD THRU THE AREA THIS MORNING. THIS FEATURE WILL STABILIZE MUCH OF THE AREA...W/ DRIER AIR SPREADING ACROSS THE REGION AND CLOUDS DISSIPATING ACROSS THE AREA. THE SWRN QUADRANT OF THE CWA...AREAS TO THE SOUTH AND WEST OF KCHO WILL REMAIN THE TARGET FOR ISOLATED SHOWERS...ANY FOG AND MID CLOUDS TODAY. OUTSIDE OF THIS AREA...ONLY A FEW BATCHES OF MID/UPPER CLOUD DECKS TODAY...SO SOLID VFR CONDITIONS THRU THE TAF PERIOD. A LIGHT NELY FLOW THIS MRNG WILL EVENTUALLY SWITCH SELY LATER TONIGHT. EAST-SOUTHEAST FLOW DEVELOPS THIS WEEKEND. IT IS BECOMING MORE LIKELY THAT A PERIOD OF MVFR/IFR CIGS WILL DEVELOP SATURDAY NIGHT INTO EARLY SUNDAY AND AGAIN SUNDAY NIGHT INTO EARLY MONDAY BEFORE A STALLED FRONTAL BOUNDARY WORKS BACK TO THE NORTH AS A WARM FRONT EARLY NEXT WEEK. PRECIPITATION WOULD LIKELY BE SHOWERS OVER THE WEEKEND...THEN THUNDERSTORMS WILL BE POSSIBLE EARLY TO MID NEXT WEEK IN THE WARM SECTOR. && .MARINE... LIGHT WINDS TODAY AND TONIGHT...AS A WEAK FRONTAL BOUNDARY SLIDES SOUTHWARD. BEHIND THE FRONT...WINDS WILL COME DOWN FROM THE NE FOR THE MRNG HAS AND EVENTUALLY TURN SELY LATER TODAY AS THE BOUNDARY DROPS SOUTH OF THE TP/CHES BAY CONFLUENCE REGION. FRONTAL BOUNDARY WILL REMAIN SOUTH OF THE WATERS THROUGH THE WEEKEND BEFORE LIFTING BACK TO THE NORTH EARLY NEXT WEEK. EAST-SOUTHEAST FLOW IS EXPECTED BUT WITH A RELATIVELY WEAK GRADIENT WINDS ARE GENERALLY EXPECT TO REMAIN BELOW SCA CRITERIA. WINDS TURN TO THE SOUTH EARLY NEXT WEEK. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...GMS/BPP NEAR TERM...GMS SHORT TERM...BPP LONG TERM...BPP AVIATION...GMS/BPP MARINE...GMS/BPP
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
143 AM EDT FRI MAY 17 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 421 PM EDT THU MAY 16 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW TROFFING ALONG THE W COAST OF THE CONUS...BROAD RIDGING OVER THE CNTRL CONUS...AND A TROF EXTENDING S INTO NEW ENGLAND. AHEAD OF THE RIDGE...IT`S BEEN A GENERALLY SUNNY DAY ACROSS THE FCST AREA. WITH THE DRY AIR NOTED ON THE 12Z KGRB SOUNDING...DWPTS HAVE FALLEN INTO THE 20S OVER PORTIONS OF THE INTERIOR W HALF OF UPPER MI...RESULTING IN RH DOWN AROUND 20PCT. SFC HIGH PRES ASSOCIATED WITH APPROACHING MID LEVEL RIDGE IS SETTLING S OVER THE UPPER GREAT LAKES AND WILL LEAD TO A QUIET NIGHT TONIGHT. TO THE W...A COUPLE OF SHORTWAVES EMERGING OVER THE WRN HIGH PLAINS ARE GENERATING SHRA/TSRA FROM ND TO NEBRASKA. THE SRN WAVE OVER WRN NEBRASKA IS THE STRONGER ONE. HEADING INTO LATER FRI...FCST WILL REVOLVE AROUND WHAT AFFECTS THESE WAVES WILL HAVE FOR UPPER MI. AS ALLUDED TO ABOVE...SFC HIGH PRES WILL LEAD TO A TRANQUIL NIGHT ACROSS THE FCST AREA. MAINLY CLEAR SKIES WITH PRECIPITABLE WATER AROUND 50PCT OF NORMAL WILL LEAD TO A QUICK TEMP DROP AFTER SUNSET. COLUMN MOISTURE BEGINS TO INCREASE OVER THE W OVERNIGHT...AND SOME OF THAT WILL MANIFEST ITSELF AS HIGH AND MID CLOUDS SPREADING E FROM THE SHRA AREA CURRENTLY OVER THE DAKOTAS. IN THE END...THIS SHOULD LEAD TO LOWEST MINS OVER THE E...THOUGH SOME OF THE TRADITIONAL COLD SPOTS OVER THE W MAY BE EQUALLY AS LOW GIVEN THE GOOD RADIATIONAL COOLING CONDITIONS EARLY IN THE NIGHT. GENERALLY FAVORED THE LOWER END OF GUIDANCE ACROSS THE BOARD IN THE INTERIOR. A FEW OF THE TYPICAL COLD SPOTS MAY SLIP JUST BLO 30F. WHETHER ANY PCPN MAKES INTO THE FCST AREA FRI IS THE BIG QUESTION. THE NAM IS VERY AGRESSIVE WITH PCPN...BRINGING OVER AN INCH OF RAIN TO KIWD BY 00Z SAT WITH PCPN SPREADING AS FAR E AS SENEY. THE GFS FOLLOWS CLOSE BEHIND THE NAM...THOUGH ITS PCPN FIELD IS DISPLACED A LITTLE FARTHER S. THE GEM HAS NO PCPN THRU 00Z SAT...THE UKMET ONLY BRINGS A FEW HUNDREDTHS TO SCNTRL UPPER MI...AND THE 12Z ECMWF IS SIMILAR WITH A FEW HUNDREDTHS ALONG THE WI BORDER WHICH IS FARTHER S AND W THAN ITS 00Z RUN. SUSPECT THE STRONGER MORE WELL-DEFINED SRN WAVE OVER THE WRN PLAINS WILL BE THE BIGGER PLAYER...RESULTING IN PCPN WITH THE NRN WAVE OVER ND GRADUALLY DRYING UP AS IT WILL HAVE LIMITED/NO MOISTURE INFLOW AND IT WILL BE ENCOUNTERING DRIER AIR TO THE E. EVEN PCPN WITH THE SRN WAVE WILL PROBABLY TEND TO DIMINISH OR AT LEAST BE SLOWER TO ARRIVE DUE TO THE DRIER AIR OVER GREAT LAKES...ESPECIALLY SINCE LOW-LEVEL TRAJECTORIES HAVE A GOOD EASTERLY COMPONENT FRI THAT WILL HELP TO MAINTAIN DRY AIR OVER THE AREA. SO PLAN WILL BE TO FAVOR THE DRIER NON NCEP MODELS FOR FRI. WHILE RELUCTANT TO ADD PCPN CHC...WILL INCLUDE A SCHC MENTION ALONG THE WI BORDER SINCE THE THERE WAS ONLY ONE MODEL (GEM) THAT HAD A COMPLETELY DRY FCST. FOLLOWING THE DRIER SCENARIO...ALSO UTILIZED LOWER DWPTS FOR FRI BY COMBINING SOME OF THE BIAS CORRECTED GUIDANCE (GEM IN PARTICULAR) WITH DWPTS CALCULATED BASED ON MIXING HEIGHT. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 421 PM EDT THU MAY 16 2013 CONFIDENCE IS STILL RATHER LOW ON QPF POTENTIAL FRIDAY NIGHT INTO SATURDAY ASSOCIATED WITH THE DEVELOPING BAROCLINIC ZONE. AS THE 850MB LOW OVER THE CENTRAL AND NORTHERN ROCKIES MOVES EAST...STRONG WARM ADVECTION AND ISENTROPIC LIFT WILL SPREAD ACROSS THE UPPER MIDWEST. THE NAM IS VERY AGGRESSIVE IN DEVELOPING SIGNIFICANT ELEVATED CONVECTION CLOSE TO THE MI/WI BORDER LATE FRI AFTN INTO FRIDAY NIGHT...WITH OVER 2 INCHES OF QPF FORECAST AT IMT AND IWD BY SAT AFTN. THE 12Z GFS HAS SHIFTED THE BAROCLINIC AXIS NORTHWARD...BUT IT IS NOT AS STRONG AS THE NAM. THE 00Z ECMWF IS OVERALL THE WEAKEST WITH THE FRONTAL BOUNDARY BUT NONETHELESS IS SIMILAR IN POSITION BUT A LITTLE SLOWER (SIMILAR TO WHAT THE 18Z NAM SHOWS). THE GEM IS MUCH FURTHER SOUTH. WITH ALL THAT SAID...THE CONSENSUS OF DETERMINISTIC AND ENSEMBLE NWP SUGGEST THAT POPS WILL NEED TO BE RAISED ACROSS THE ENTIRE AREA (EXCEPT EAST 1/3) FRIDAY NIGHT INTO SATURDAY. WITH THE STRONGLY CONFLUENT FLOW AND DRY AIR IN PLACE...DO NOT EXPECT THE HEAVY PCPN PER THE NAM FORECAST...HOWEVER SOME SHOWER ACTIVITY FRIDAY NIGHT INTO SATURDAY IS EXPECTED ESPECIALLY CLOSER TO THE WI BORDER WHERE THE BETTER MOISTURE AND BETTER LIFT ASSOCIATED WITH THE FRONTAL ZONE IS LOCATED. BY SATURDAY AFTERNOON...THE BAROCLINIC ZONE SHIFTS NORTH OF THE AREA WITH THE BEST MOISTURE TRANSPORT CLOSER TO THE LOW TO THE WEST OF THE AREA. IN FACT...WILL LIKELY SEE SOME CLEARING LATE SAT AFTN AS THE WARM SECTOR MOVES OVER THE AREA AND DRIER AIR ADVECTS INTO THE AREA. WILL MAINTAIN LOW CHANCE POPS WEST SAT AFTN/NIGHT...BUT GENERALLY DRY ELSEWHERE. SUNDAY SHOULD END UP BEING GENERALLY DRY WITH THE BEST MOISTURE AND LOW LVL JET TO THE WEST OF THE AREA. NAM AND GFS ARE VERY AGGRESSIVE IN WARMING 850MB TEMPS TO +18C ACROSS THE SOUTH...BUT AM THINKING THE MORE CONSERVATIVE ECMWF WITH 850MB TEMPS AROUND +14 SEEMS MORE REASONABLE. REGARDLESS...SHOULD BE A NICE DAY WITH PERHAPS A CHANCE OF SHOWERS AND THUNDERSTORMS LATE IN THE DAY SUNDAY ACROSS THE WEST. RATHER UNSETTLED WEATHER WILL CONTINUE THROUGH THE EARLY PART OF NEXT WEEK WITH THE UPPER LOW OVER THE NORTHERN PLAINS BEING RATHER STUBBORN TO MOVE OUT. THIS WILL KEEP THE BAROCLINIC ZONE NEARBY THROUGH WEDNESDAY BEFORE AN UPPER TROUGH OVER HUDSON BAY DIVES SOUTH AND ALLOWS THE FRONT TO MOVE SOUTH OF THE AREA BY THURSDAY. WITH THAT SAID...MON-WED LOOKS QUITE WET AT TIMES WITH SOME HEAVY RAIN CERTAINLY POSSIBLE. ALTHOUGH 850MB TEMPS WILL BE AROUND +10C THROUGH WED...EASTERLY FLOW DUE TO THE LOW STAYING SOUTH OF THE AREA AS WELL AS PLENTIFUL CLOUDS WILL KEEP TEMPS COOL NEAR LAKE SUPERIOR. INLAND TEMPS WILL LIKELY STAY NEAR NORMAL...BUT TEMPS CLOSER TO LAKE SUPERIOR WILL BE IN THE UPPER 50S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 142 AM EDT FRI MAY 17 2013 ALTHOUGH HI CLDS WL BE ON THE INCREASE THRU TODAY...EXPECT VFR CONDITIONS TO PREVAIL THRU THIS FCST PERIOD WITH DRY E WIND OUT OF HUDSON BAY HI PRES. IF THIS HI RETREATS...SOME -SHRA MAY IMPACT IWD THIS EVNG. BUT MENTIONED ONLY VCSH ATTM GIVEN LIKELY PERSISTENCE OF DRY AIR ASSOCIATED WITH STUBBORN HUDSON BAY HI PRES. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 421 PM EDT THU MAY 16 2013 LIGHT WINDS WILL BE THE RULE ACROSS LAKE SUPERIOR TONIGHT WITH HIGH PRES OVER THE UPPER LAKES. WHILE THE HIGH WILL BE SHIFTING E FRI...A MESO HIGH MAY LINGER OVER ERN LAKE SUPERIOR THRU THE DAY. THIS WILL KEEP WINDS LIGHT OVER THE E...BUT E TO NE WINDS WILL BEGIN TO INCREASE OVER THE W. HEADING THRU THE WEEKEND INTO EARLY NEXT WEEK...PRES GRADIENT OVER THE UPPER LAKES WILL SLOWLY TIGHTEN BTWN LOW PRES SLOWLY MOVING FROM THE WRN PLAINS TOWARD THE UPPER MISSISSIPPI VALLEY AND HIGH PRES BUILDING IN THE VCNTY OF WRN HUDSON BAY. THIS WILL LEAD TO EASTERLY WINDS GRADUALLY INCREASING INTO GENERALLY THE 15-25KT RANGE. COULD BE SOME PERIODS OF HIGHER WINDS AT TIMES EARLY NEXT WEEK...ESPECIALLY OVER WRN LAKE SUPERIOR WHERE FUNNELING/CHANNELING WILL ENHANCE THE WINDS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...MRD AVIATION...KC MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
404 AM CDT Fri May 17 2013 .SHORT TERM...(Today through Saturday night) Issued at 403 AM CDT FRI MAY 17 2013 Closed upper low over south central MO will continue an eastward track and move away from the CWA today. Could see an isolated shower or storm over the far eastern counties later this morning and early afternoon as any remaining vorticity lobes rotate cyclonically westward. Stratus has formed over the southern CWA. These clouds on the northwest side of the upper low an increasingly moist boundary layer. 06z RAP has best handle on the current low cloud trends and followed. Airmass over the CWA is very similar to yesterday. However, except for the far northwest corner of MO believe max temperatures today may be a few degrees cooler than yesterday due to increased cloud cover. The earlier upstream convection over KS and NE was tied to a couple of weak vorticity lobes. Convection has all but dissipated and dont` expect it to reform today. Shortwave ridging aloft is progged to amplify as it moves east across the Central and Southern Plains this afternoon through Saturday. This should yield dry and warmer conditions on Saturday. Expect max temperatures in the middle to upper 80s. Saturday night is looking a tad more interesting as it no longer looks dry. NAM/GFS/ECMWF/GEM have been giving signals for the past couple of runs that elevated convection will form Saturday evening over eastern KS/western MO and quickly advance northeast Saturday night. With a stout elevated mixed layer providing an impediment to surface based convection, any activity will need to rely on isentropic ascent and a ramping up of the h8 low level jet.....and we have that. So, have no qualms in adding at least slight chance PoPs for Saturday night to most of the CWA. Even went with chance PoPs over the northeastern CWA as the initial activity will have had time to increase in coverage as it moves quickly northeast. .LONG TERM...(Sunday through Thursday) Issued at 403 AM CDT FRI MAY 17 2013 For Sunday, there remains a good chance for severe weather from the afternoon into the overnight hours. A trough is expected to move into the Plains by Sunday afternoon leading to a surface low that will move to our north. This will result in the entire area being in a broad warm sector with dewpoints likely in the mid to upper 60s. Model soundings show a strong CAP over the region but also with the potential for elevated showers/storms earlier in the day. This possible area of precipitation should move east into the Mississippi Valley by the afternoon leaving eastern Kansas and western Missouri to see better destabilization during the afternoon. CAPE values in the 2500 to 3500 J/kg range look likely given forecast dewpoints so we will see moderate to strong instability build across our western zones. The finer scale details of what impact the convection earlier in day will have will only be able to be resolved during the nowcast period. But strong instability and 0-6KM shear in the 40 to 50 kt range, oriented more normal to any initiating boundary, indicates supercells would be the most likely convective mode initially. Hodographs show a good amount of curvature by the afternoon and this is increased during the evening as the low level jet restrengthens overhead. Storms will likely initiate over eastern Kansas during the afternoon hours and become supercells. As winds veer into the evening and overnight hours storms should organize into more of a line/ convective complex. Large hail, damaging winds and a few tornadoes are possible with the initial storms before the convective mode changes and damaging winds becomes the primary concern. Monday will be greatly dependent upon what happens Sunday night, and as such confidence is quite a bit lower. Latest guidance suggest that the front will be nearly east of us by the evening hours with winds across the area veered southwesterly. Shear and instability are still supportive of severe weather, but the chances should be either across our eastern to southern zones or even east of the forecast area. We will really need to see how the weather pans out Sunday before a saying anything with any level of certainty. For the remainder of the extended forecast, the upper trough that affected the area Sunday and Monday should have cutoff over the Upper Midwest. Another segment of the upper trough will move through Wednesday and as a result there may be a few showers or storms across northern Missouri into central and eastern Missouri. A few showers and storm will remain a possibility into Thursday as northern portions of the forecast are still under the influence of the Upper Midwest upper low. The effects of the upper low will diminish by Friday as upper ridging spreads into the Plains. This will result in a warm up with drier conditions more likely for the weekend. The severe potential looks rather low for this stretch of time. && .AVIATION...(For the 06Z TAFS through 06Z Friday Night) Issued at 1048 PM CDT THU MAY 16 2013 Only issues for the terminals over the next 24 hours will be this morning as nearly clear skies might allow for the development of light fog in the morning. However, confidence is low owing to the amount of dry air in place across the region. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ SHORT TERM...MJ LONG TERM...CDB AVIATION...Cutter
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
345 AM CDT FRI MAY 17 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 313 AM CDT FRI MAY 17 2013 THE MAIN FEATURE OF INTEREST TODAY IS THE UPPER LOW WHICH PROFILER AND WATER VAPOR SUGGEST IS CURRENTLY LOCATED ACROSS EXTREME SRN MO NEAR WEST PLAINS. THE MODELS ARE IN RELATIVELY GOOD AGREEMENT TRACKING THE LOW E/NEWD TODAY WITH THE MORE SRN POSITION OF THE LOCAL WRF AND RUC PREFERRED. THIS TRACK WOULD TAKE THE LOW ACROSS THE EASTERN OZARKS THIS MORNING AND INTO SRN IL THIS AFTENOON. THE BIGGEST UNCERTAINTY WITH THIS SYSTEM IS THE N/NW EXTENT OF PRECIPITATION AND COVERAGE. CLOUD TOPS HAVE BEEN COOLING THE LAST FEW HOURS IS ASSOCIATION WITH AN INCREASING AMOUNT OF SHOWERS. THE EXPLICIT GUIDANCE GENERALLY DEPICTS SCATTERED COVERAGE DIMINISHING WITH NORTHWARD EXTENT. THIS SEEMS REASONABLE AND HAS BEEN GENERALLY ACCEPTED WITH THE HIGHEST POPS ACROSS SE MO INTO SRN IL. THE THREAT OF CONVECTION SHOULD INCREASE LATER THIS MORNING IS ASSOCIATION WITH HEATING AND DESTABILIZATION. THE UPPER LOW SHOULD BE IN SRN IL BY EARLY EVENING...DEPARTING TO THE EAST NORTHEAST. ANY PRECIPITATION IN THE WAKE OF THE LOW SHOULD BE STRONGLY TIED TO HEATING...DISSIPATING DURING THE EVENING. GLASS .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 313 AM CDT FRI MAY 17 2013 SATURDAY LOOKS LARGELY DRY AS A RIDGE ALOFT BUILDS INTO THE AREA IN ASSOCIATION WITH OVERALL UPSTREAM AMPLIFICATION. LOW LEVEL WAA WILL INCREASE AND THIS COMBINED WITH LESS CLOUD COVER WILL RESULT IN WARMER TEMPERATURES. THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL RE-ENTER THE PICTURE ON SAT NIGHT IN RESPONSE TO LOW LEVEL WAA/MCON VIA A SWLY LLJ...BRINGING THE POTENTIAL FOR ELEVATED ACTIVITY TO THE NORTH OF A SLOWLY LIFTING WARM FRONT. THE HIGHEST PROBABILIT AT THIS TIME APPEARS TO BE ACROSS NRN MO INT CENTRAL IL. THERE COULD BE ONGOING/RESIDUAL ELEVATED ACTIVITY NORTH OF THE WARM FRONT ACROSS NE MO/WEST CENTRAL IL ON SUNDAY MORNING. OTHERWISE INCREASING SOUTHERLY FLOW AND WAA SHOULD RESULT IN CONTINUED WARMER TEMPERATURES WITH SOME LOCATIONS PUSHING 90 DEGREES. A VERY ACTIVE PERIOD WILL BEGIN TO UNFOLD LATE SUNDAY AFTERNOON AND CONTINUE THROUGH AT LEAST TUESDAY NIGHT AS RATHER DEEP AND BROAD UPPER TROF/UPPER LOW MOVES SLOWLY EAST AND A SERIES OF SHORT WAVES EJECT E/NEWD. A MOIST AND VERY UNSTABLE AIR MASS WILL BE IN PLACE AND THIS COMBINED WITH FAVORABLE DEEP LAYER SHEAR WILL SUPPORT MULTIPLE SEVERE WEATHER EPISODES OVER A 3 DAY PERIOD MIGRATING WEST TO EAST ACROSS THE CWA WITH THE MOST ACTIVE PERIOD FROM MONDAY THROUGH TUESDAY NIGHT. GLASS && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1158 PM CDT THU MAY 16 2013 LO CIGS ASSOCIATED WITH MORE OF THE CORE OF THE UPPER LEVEL SYSTEM TO OUR SW WILL EDGE CLOSER TO CNTRL MO AND STL METRO LATE TONIGHT AND THEN GET SHUNTED OFF TO THE E...AUGMENTED ON FRIDAY BY DIURNAL INFLUENCES...WITH CLEARING EXPECTED HEADING INTO FRIDAY EVENING...FOR A TIME. MAY TRIP IFR CIGS AT KCOU AND STL METRO SITES LATE TONIGHT AND EARLY FRIDAY MORNING BUT STILL THINK IFR SHOULD STAY TO THE S. A BETTER LO STRATUS AND FOG SETUP APPEARS TO EXIST ON FRIDAY NIGHT...ESPECIALLY FOR STL METRO SITES...AS MOISTURE NEVER REALLY GETS SCOURED OUT BEHIND SYSTEM AND WITH SOME CLEARING EXPECTED AND LIGHT WINDS. ANOTHER ROUND OF SCT TSRA APPEARS IN THE OFFING FRIDAY AFTERNOON AS UPPER LEVEL SYSTEM WILL STILL BE CLOSE ENOUGH. SPECIFICS FOR KSTL...DETERIORATING CONDITIONS EXPECTED LATE TONIGHT AND EARLY FRIDAY MORNING WITH IFR POSSIBLE BUT FOR NOW HAVE FAVORED THE LO-END MVFR OF THE PREVIOUS TAF...IMPROVEMENT TO CIGS ABOVE 2KFT EXPECTED ON FRIDAY WITH PARTIAL CLEARING AND PERHAPS ANOTHER ROUND OF LO STRATUS AND FOG FRIDAY NIGHT. BEST PCPN CHCS AFTER EARLY THIS EVENING WILL BE FRIDAY AFTERNOON WITH TSRA DEVELOPING WITH THE HEATING OF THE DAY. TES && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS BILLINGS MT
346 AM MDT FRI MAY 17 2013 .SHORT TERM...VALID FOR TDY AND SAT... BENEFICIAL MOISTURE IS ON THE WAY THE NEXT SEVERAL DAYS THANKS TO A 500-HPA TROUGH. UP TO AN INCH OF RAINFALL IS VERY POSSIBLE OVER MANY AREAS WHEN ALL IS SAID AND DONE...SO FORECAST POPS HAVE ONCE AGAIN BEEN LEVERAGED UPWARD WITH THIS FORECAST SO THAT 80 PERCENT PROBABILITIES OF MOISTURE ARE ADVERTISED IN AT LEAST SOME PERIODS OF THE FORECAST. HIGHS HAVE ALSO BEEN LOWERED TODAY AND SAT BASED ON EXPECTED CLOUD COVER AND PRECIPITATION. TODAY...DIFFLUENCE ASSOCIATED WITH A MODEST 300-HPA JET STREAK ON THE ORDER OF 60 TO 70 KT SHOULD HELP SHOWERS BLOSSOM ACROSS SOUTH CENTRAL MT THIS MORNING. BILLINGS MAY BE ON THE EAST EDGE OF THIS MOISTURE BASED ON RECENT RAP AND HRRR RUNS. THEN...BY AFTERNOON A DESTABILIZING BOUNDARY LAYER AND EASTWARD MOVEMENT OF THE DYNAMIC FORCING TIED TO THE UPPER-LEVEL JET SHOULD FOSTER CONVECTION EAST OF THE MORNING PRECIPITATION. THE 00 UTC GFS...ECMWF...AND RECENT RAP AND HRRR RUNS ALL AGREE WELL ON THIS NOTION. BOTH THE ARW AND NMM CORES OF THE HIGH-RESOLUTION...CONVECTION-ALLOWING WRF MODELS MAKING UP THE SPC STORM-SCALE ENSEMBLE OF OPPORTUNITY ALSO KEY IN ON THIS CONVECTION...WHICH SHOULD FROM SOMEWHERE ALONG A BILLINGS TO GREYBULL LINE IN THE 18 TO 21 UTC TIME FRAME. INSTABILITY WILL BE SUFFICIENT FOR AT LEAST EMBEDDED THUNDER...AND AS THE ACTIVITY GETS INTO SOUTHEASTERN MT...IT WILL HAVE ACCESS TO MUCAPE UPWARDS OF 1000 J/KG. GIVEN STEEPENING MID-LEVEL LAPSE RATES AND 50 KT OF 0-6 KM BULK SHEAR...THERE IS ENOUGH OF A RISK OF SEVERE STORMS IN THE BROADUS AND EKALAKA CORRIDOR IN PARTICULAR FOR US TO MAINTAIN A MENTION OF IT IN THE FORECAST. LARGE HAIL SHOULD BE THE PRIMARY THREAT. HOWEVER...QUESTIONS ABOUT DESTABILIZATION EXIST /WITH THE 00 UTC NAM SUGGESTING LOWER MUCAPE/ OWING TO CLOUD COVER...AND IT IS STILL POSSIBLE SHEAR WILL BE TOO STRONG FOR LONG-LIVED OR DEEP UPDRAFTS TO SUSTAIN THEMSELVES. NOTE THAT THERE IS A RISK OF SOME ISOLATED STORMS FORMING IN SOUTHEASTERN MT DURING PEAK HEATING IN ADVANCE OF THE ACTIVITY WE EXPECT TO MOVE INTO THAT AREA BY LATER IN THE AFTERNOON OR EVENING...THOUGH CONFIDENCE IN THAT IS LOW. TONIGHT...WE KEPT A MENTION OF SEVERE WEATHER IN THE FORECAST FOR FAR SOUTHEASTERN MT AND PARTS OF SHERIDAN COUNTY WY UNTIL 06 UTC. SREF-BASED SEVERE THUNDERSTORM PROBABILITIES SUGGEST THE RISK MAY CONTINUE /AT LEAST ON A MARGINAL BASIS/ FOR A WHILE AFTER SUNSET. OTHERWISE...OUR POP FORECAST IS BASED ON THE IDEA THAT A RELATIVE BREAK IN MORE WIDESPREAD PRECIPITATION COULD OCCUR AFTER ABOUT 06 UTC AS CONVECTION SHIFTS INTO THE DAKOTAS AND AS THE FORCING FROM THE 300-HPA JET SHIFTS INTO NORTHERN MT. THE 03 UTC SREF ARGUES A DIFFERENT STORY THOUGH SINCE IT BRINGS ANOTHER MORE DEFINED BATCH OF FORCING AND SHOWERS INTO SOUTH CENTRAL MT AFTER MIDNIGHT. THAT IS A GOOD EXAMPLE OF THE SUBTLE DETAILS THAT ARE STILL NOT WORKED OUT WITH THIS EVENT. BY SAT...CONFIDENCE IN THE FORECAST STARTS DECREASING A BIT SINCE GUIDANCE BEGINS SHOWING SOME DIFFERENCES IN HOW IT HANDLES ENERGY ASSOCIATED WITH THE MID- AND UPPER-LEVEL TROUGH. ADD TO THAT SOME GRID-SCALE FEEDBACK RELATED TO MODEL CONVECTIVE SCHEMES AND THERE ARE CERTAINLY UNCERTAINTIES TO CONTEND WITH. THE GFS SOLUTION WAS LEAST ROBUST WITH QPF OVER SOUTHERN MT...BUT IT ALSO SUFFERS MORE FROM GRID-SCALE FEEDBACK THAN MOST OTHER SOLUTIONS...AND IT LOOKS LIKE A RELATIVE OUTLIER. THE REST OF THE GUIDANCE IS WETTER...AND SO WE CAUTIOUSLY PUSHED POPS UPWARD ANOTHER NOTCH IN MANY PLACES. MID-LEVEL LAPSE RATES STAY MARGINALLY FAVORABLE FOR THUNDER...AND SO WE KEPT AT LEAST AN ISOLATED MENTION OF IT IN THE FORECAST FOR SAT AND SAT NIGHT. SCHULTZ .LONG TERM...VALID FOR SUN...MON...TUE...WED...THU... STILL SOME UNCERTAINTY ON WHETHER THE WET SCENARIO WILL HANG ON SUNDAY AND MONDAY. THE NAM AND ECMWF WERE INDICATING THAT IT WOULD AS THEY CUT A LOW OFF OVER WESTERN SOUTH DAKOTA AND VERY SLOWLY DRIFT IT EAST MONDAY. THIS WOULD WRAP SOME DECENT MOISTURE AROUND THE LOW INTO THE FORECAST AREA WITH STRONG UPSLOPE FLOW. THE GFS...ON THE OTHER HAND...MOVES THE UPPER LOW FARTHER EAST MUCH QUICKER. BOTH THE ECMWF AND GFS HAVE BEEN CONSISTENT WITH THEIR SOLUTIONS. DID RAISE POPS FOR SUNDAY AND MONDAY AS THE GFS WAS THE ODD MODEL OUT ON THE DRIER SIDE OF THINGS. DID LOWER TEMPERATURES SUNDAY AND MONDAY GOING WITH A WETTER SCENARIO. A BIT OF BLOCKING PATTERN SETS UP FOR WEDNESDAY THROUGH NEXT FRIDAY AS AN UPPER RIDGE PINCHES OFF FROM WYOMING INTO SOUTHERN CANADA. THE HIGH WILL BE PLACED BETWEEN THE UPPER LOW TO THE EAST AND ANOTHER MUCH DEEPER LOW MOVING INTO WASHINGTON. THE WESTERN UPPER LOW DOES NUDGE THINGS EAST WEDNESDAY AND PRODUCES SOUTHERLY FLOW OVER WYOMING AND MONTANA. ORDINARILY A SOUTH FLOW WOULD MEAN PRECIPITATION...BUT MODELS WERE PULLING IN DRIER MID LEVEL AIR. A SERIES OF WEAK SHORTWAVES SPIN OFF THE WESTERN LOW AND TRAVERSE THROUGH THE AREA THROUGH THE END OF THE EXTENDED FOR ASCENT. WILL HAVE TO LOOK OUT FOR LOW LEVEL MOISTURE INCREASING HOWEVER AS SOUTHEAST FLOW DEVELOPS OVER THE EASTERN HALF OF THE FORECAST AREA. WILL BROAD BRUSH LOW POPS FOR NOW AND WAIT AND SEE HOW THIS PATTERN PANS OUT. TWH && .AVIATION... SCATTERED SHOWERS THIS MORNING WILL BECOME MORE WIDESPREAD BY EARLY AFTERNOON. THERE WILL BE THUNDERSTORMS EMBEDDED WITHIN THE SHOWERS BUT THE MOST LIKELY LOCATION FOR ORGANIZED THUNDERSTORMS WILL BE EAST OF KBIL. SOME OF THE SHOWERS WILL CONTAIN MODERATE TO BRIEFLY HEAVY RAIN AND COULD LOWER CONDITIONS TO MVFR. SOME THUNDERSTORMS COULD BE QUITE STRONG FROM LOCATIONS EAST AND SOUTH OF A KSHR TO KMLS LINE. MOUNTAINS WILL BE OBSCURED. TWH && .PRELIMINARY POINT TEMP/POPS... TDY SAT SUN MON TUE WED THU ------------------------------------------------------- BIL 065 053/065 049/061 048/062 045/071 047/071 049/071 8/T 88/T 75/T 55/W 31/B 13/T 31/B LVM 061 043/063 043/057 040/059 037/066 041/071 040/067 8/T 88/T 84/T 55/W 31/B 23/T 33/T HDN 070 053/067 048/062 047/062 044/071 045/073 049/074 8/T 88/T 75/T 66/W 31/E 13/T 31/B MLS 072 055/068 049/065 049/062 046/068 046/071 050/071 6/T 88/T 75/T 65/W 53/W 23/T 32/T 4BQ 074 054/068 047/063 047/060 043/063 044/071 048/071 6/T 87/T 65/T 66/W 53/W 22/T 22/T BHK 071 053/068 047/062 047/060 043/061 043/067 048/067 5/T 77/T 65/T 65/W 53/W 22/W 22/T SHR 072 048/065 044/059 043/057 040/064 040/073 046/072 6/T 57/T 65/T 66/W 42/W 13/T 31/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1100 PM MDT Thu May 16 2013 .DISCUSSION... Update forthcoming. Have made adjustments to the pop and weather grids. Moist and unstable flow aloft continues ahead of an upper trof approaching from the west. Latest RUC analysis keeps overnight precipitation mainly over the southwest so have lowered pops across central and northern portions of the county warning area into Friday morning. Remainder of forecast looks on track. Emanuel && .AVIATION... UPDATED 0500Z. Moist and unstable flow will continue as an upper level trough moves slowly east over the region. Disturbances will bring scattered to numerous showers to the southern half of Central Montana through 00z Friday. In the north VFR conditions should prevail tonight with areas of MVFR in and around isolated showers before 12z. Central Montana will see more widespread stratiform rain and mountain snow develop after 12z spreading to North Central Montana after 18z. Widespread MVFR/IFR conditions and mountain obscuration is expected. && .PREV DISCUSSION...Issued 257 PM MDT Thu May 16 2013 Thursday through Saturday...Moist flow aloft and multiple weak upper level disturbances will move across the area ahead of a low pressure trough that will move across the area throughout the weekend. Showers and afternoon thunderstorms will increase in coverage through the weekend. No severe thunderstorms are expected at this time however isolated strong gusty winds and hail will be possible. The area with the largest chance of widespread precipitation will continue to be Southwest Montana where low level moisture will be the most abundant throughout the period. Less chance of wide spread precipitation to the north as the Moist flow at mid level dramatically decreases north of the Little Belt Mountains. Suk SATURDAY NIGHT THROUGH THURSDAY...FAIRLY GOOD MODEL AGREEMENT THROUGH THE PERIOD. EXPECT AN UNSETTLED WEATHER PATTERN AS THE BROAD UPPER TROUGH...ALREADY IN PLACE...MOVES EASTWARD. ON TUESDAY WEAK RIDGING BUILDS INTO THE AREA. THE ECMWF HAS THE RIDGE BUILDING A LITTLE STRONGER NORTH INTO MONTANA...BUT THE RIDGING IS SHORT LIVED. BY TUESDAY NIGHT THE AREA HAS DIFFLUENT FLOW WHILE BETWEEN SYSTEMS. BY WEDNESDAY MORNING THE CWA WILL START TO FEEL THE EFFECTS OF THE LOW IN THE PAC NW. AS FAR AS PRECIPITATION GOES...MODEL SOUNDINGS CONTINUE TO SHOW DEEP MOISTURE THROUGH MONDAY MORNING...BUT NOT AS MUCH INSTABILITY. MOST OF PRECIPITATION WILL FALL AS RAIN WITH THE EXCEPTION OF THE HIGHEST OF ELEVATIONS. THIS WEEKEND`S SYSTEM WILL BRING MUCH NEEDED RAINFALL OVER MUCH OF THE STATE...WITH ADDITIONAL CHANCES BY THE END OF NEXT WEEK. MERCER && .PRELIMINARY POINT TEMPS/POPS... GTF 64 45 61 44 / 50 50 70 50 CTB 64 42 63 41 / 50 40 50 40 HLN 65 46 63 45 / 50 60 80 60 BZN 66 42 62 41 / 50 70 80 70 WEY 61 43 56 39 / 60 60 70 60 DLN 63 43 59 41 / 70 70 80 80 HVR 71 47 68 46 / 50 60 60 50 LWT 64 46 59 43 / 50 80 70 70 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS HASTINGS NE
435 AM CDT FRI MAY 17 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 406 AM CDT FRI MAY 17 2013 ANOTHER SEASONABLY WARM AFTERNOON IS EXPECTED ACROSS THE REGION AS WEAK UPPER LEVEL RIDING WORKS ITS WAY IN FROM THE WEST. EARLY THIS MORNING...SOME SHOWER AND THUNDERSTORM ACTIVITY HAS DEVELOPED TO THE WEST OF THE LOCAL AREA...LIKELY A FACTOR OF THE LOW LEVEL JET PROVIDING JUST ENOUGH FORCING ACROSS WESTERN KANSAS EARLY THIS MORNING TO SPARK SOME CONVECTION. HOWEVER WITH THIS ACTIVITY SHOWING SIGNS OF DIMINISHING AND LITTLE INSTABILITY TO KEEP IT GOING AS IT APPROACHES THE LOCAL AREA...DECIDED TO JUST ADD A SLIGHT CHANCE OF SPRINKLES ACROSS THE WESTERN FRINGES OF OUR FORECAST AREA THROUGH 8 AM TO ACCOUNT FOR ANY REMNANTS OF THIS CONVECTION AS IT WORKS EAST. OTHERWISE...HAVE SEEN SOME PATCHY FOG DEVELOP ACROSS AROUND LXN AND ODX EARLY THIS MORNING AS TEMPERATURES HAVE FALLEN TO REACH THE DEWPOINTS AT THESE LOCATIONS THE PAST COUPLE OF HOURS...AND THINK SOME FURTHER DEVELOPMENT WILL BE POSSIBLE OVER THE NEXT FEW HOURS...GENERALLY WEST OF HIGHWAY 281. HRRR AND SREF HAVE BOTH BACKED OFF ON POTENTIAL FOG DEVELOPMENT FOR THIS MORNING...AND EXPECT ANY FOG THAT DOES MANAGE TO DEVELOP TO BE FAIRLY PATCHY AND SHORT LIVED...AND CORRESPONDINGLY TRIMMED BACK COVERAGE FROM PREVIOUS FORECAST. FOR THIS AFTERNOON...EXPECT TEMPERATURES TO CLIMB BACK INTO THE MID AND UPPER 80S ACROSS THE ENTIRE FORECAST AREA AS PARTLY CLOUDY TO MOSTLY SUNNY SKIES WILL WORK THEIR WAY IN ACROSS THE REGION AS THE RIDGE TRANSITIONS EASTWARD. ADDITIONALLY...WITH THE RIDGE AXIS MOVING OVERHEAD...850MB TEMPS WILL CLIMB A COUPLE OF DEGREES FROM YESTERDAYS VALUES...FURTHER AIDING IN A SEASONABLY WARM AFTERNOON. AT THE SURFACE...EXPECT A SURFACE TROUGH TO DEVELOP ON THE LEE SIDE OF THE ROCKIES BY EARLY AFTERNOON...AND THIS SHOULD HELP INCREASE THE PRESSURE GRADIENT JUST ENOUGH TO RESULT IN BREEZY SOUTHERLY WINDS...GENERALLY 15 TO 25 MPH IN MOST SPOTS. FOR TONIGHT...SOME OF THE GUIDANCE IS ATTEMPTING TO DEVELOP SOME CONVECTION ACROSS THE HIGH PLAINS AND TRANSITION IT EASTWARD AROUND SUNSET. WHILE THERE WILL BE PLENTY OF INSTABILITY TO JUSTIFY CONVECTION TO OUR WEST...A DECENT CAP IS FORECAST AROUND 800 MB WITH LITTLE IN THE WAY OF FORCING TO JUSTIFY MUCH CONVECTION ACROSS THE LOCAL AREA. EVEN SO...WITH 00Z WRF BEING THE MOST AGGRESSIVE TRANSLATING SOME OF THE REMNANTS OF THE HIGH PLAINS CONVECTION ACROSS THE LOCAL AREA DURING THE EVENING HOURS...FELT JUSTIFIED ADDING A FEW SPRINKLES TO THE NORTHWESTERN QUADRANT OF THE LOCAL AREA JUST IN CASE A FEW SHOWERS ARE ABLE TO MAINTAIN THEMSELVES AS THEY TRACK EAST. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 408 AM CDT FRI MAY 17 2013 THUNDERSTORM CHANCES THIS WEEKEND WILL BE THE PRIMARY FOCUS OF LONG TERM. IT SHOULD BE NOTED THAT THERE ARE CHANCES FOR PRECIPITATION NEARLY EVERYDAY OVER THE LONG TERM...BUT THE CHANCE FOR SEVERE THUNDERSTORMS APPEARS TO BE BEST ON SATURDAY AT THE MOMENT. AN UPPER LEVEL TROUGH WILL BEGIN TRANSITIONING OVER THE WEST COAST TODAY AND WILL EVENTUALLY MOVE EASTWARD INTO THE INTERMOUNTAIN WEST ON SATURDAY. AT THE SURFACE ON SATURDAY...A LEE LOW WILL FORM AHEAD OF THE UPPER LEVEL TROUGH...AND A COLD FRONT WILL DRAPE INTO NEBRASKA WHICH SHOULD HELP TO INITIATE THUNDERSTORMS ACROSS THE OUTLOOK AREA LATER IN THE AFTERNOON. THERE WILL BE A STRONG CAPPING INVERSION IN PLACE AT THE MID-LEVELS...SO THIS WILL NEED TO ERODE/BREAK BEFORE ANY CONVECTION CAN INITIALIZE. A FEW THINGS SHOULD HELP TO GET STORMS INITIATED LATER IN THE AFTERNOON THOUGH. FOR ONE...THE ADVECTION OF STEEPER LAPSE RATES IN THE MID-LEVELS WILL HELP WEAKEN THIS CAP. SECONDLY...THE COLD FRONT PROGGED TO SLIDE OVER THE REGION SHOULD SERVE AS A GOOD LIFTING MECHANISM TO HELP GET CONVECTION STARTED IN THE AFTERNOON. LASTLY...MODERATE TO STRONG INSTABILITY ON THE ORDER OF 3000-4000 J/KG OF MLCAPE IS FORECAST BY 00Z SUNDAY...SO ANY STORMS THAT DO FORM WILL HAVE THE ABILITY TO BECOME STRONG TO SEVERE. AS THE EVENT UNFOLDS LATER INTO THE EVENING...THE FORMATION ON AN MCS IS DEFINITELY POSSIBLY AND SHOULD POSE A PRIMARY THREAT OF DAMAGING WINDS. HAIL WILL BE THE PRIMARY THREAT EARLY IN THE EVENT...ESPECIALLY THE MORE ISOLATED/DISCRETE CELLS WITH STRONG UPDRAFTS. ITS ALSO WORTH NOTING THE NAM...GFS...AND EC ALL SHOW STRONG 0-1 KM BULK SHEAR ON THE ORDER OF 25 TO 30 KTS. DEEP LAYER SHEAR WAS NOT AS IMPRESSIVE BUT STILL HAD VALUES AROUND 35 KTS. THE SHEAR ENVIRONMENT COUPLED WITH STRONG INSTABILITY WOULD SUGGEST SUPERCELLS COULD FORM AND WITH ANY SUPERCELL...THERE WILL ALSO BE A TORNADO THREAT. MOVING INTO SUNDAY...THUNDERSTORMS WILL LIKELY CONTINUE MOVING EASTWARD ACROSS THE OUTLOOK AREA. THE SEVERE THREAT WILL BE OVERALL LIMITED...BUT OUR EASTERN COUNTIES COULD POTENTIALLY SEE THE SEVERE THREAT CONTINUE INTO THE AFTERNOON HOURS ON SUNDAY...PRIMARILY EAST OF HIGHWAY 281. NEXT WEEK WILL HAVE POPS ANYWHERE FROM 10 TO 30 PERCENT NEARLY EVERYDAY. THESE POPS ARE ROOTED IN THE TROUGH CURRENTLY OVER THE WEST COAST WHICH IS FORECAST TO MEANDER AROUND THE GREAT PLAINS NEXT WEEK. THE BIGGEST DISADVANTAGE IN THE LONG TERM IS THE LACK OF CONSISTENCY AND AGREEMENT BETWEEN THE MODELS. THROUGH THE WEEKEND...TEMPERATURES WILL BE ABOVE NORMAL...WHILE NEXT WEEK WILL BE CLOSER TO NORMAL FOR THIS TIME OF YEAR. HIGHS ON TUESDAY APPEAR TO BE THE ONE EXCEPTION...WITH TEMPERATURES MORE LIKELY TO BE SLIGHTLY BELOW NORMAL FOR THIS TIME OF YEAR. && .AVIATION...(FOR THE 06Z KGRI TAF THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1220 AM CDT FRI MAY 17 2013 VFR CONDITIONS ARE EXPECTED TO PREVAIL AT KGRI FOR THE NEXT 24 HOURS. EXPECT THE MID LEVEL CLOUD DECK COVERING MUCH OF NEBRASKA THIS EVENING...TO GRADUALLY CLEAR OVERNIGHT AS A SHORT WAVE RIDE TRANSITIONS ACROSS THE PLAINS. THIS SHOULD PUT AN END TO ANY REMAINING SHOWER ACTIVITY AS WELL. WHILE WINDS WILL HAVE A SLIGHT SOUTHEASTERLY COMPONENT AND DEWPOINTS WILL REMAIN ELEVATED OVERNIGHT...MAY SEE SOME PATCHY FOG DEVELOPMENT AS INDICATED BY SOME OF GUIDANCE...BUT CONFIDENCE OF THIS IS LOW...AND DID NOT INCLUDE IN TAF. OTHERWISE...EXPECT A SURFACE TROUGH OF LOW PRESSURE TO DEVELOP TO THE WEST TOMORROW AFTERNOON...AND THIS SHOULD HELP TO TIGHTEN UP THE PRESSURE GRADIENT...SO WENT AHEAD AND INCLUDED WIND GUSTS INTO THE LOWER 20S TOMORROW AFTERNOON. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...SAR LONG TERM...GUERRERO AVIATION...SAR
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
258 AM EDT FRI MAY 17 2013 .SYNOPSIS... FAIR WEATHER WILL PERSIST INTO SATURDAY, WITH SEASONABLE DAYTIME TEMPERATURES AND COOL OVERNIGHTS. A WEAK FRONT MAY BRING ISOLATED SHOWERS TO THE REGION ON SUNDAY, THOUGH MOST AREAS WILL REMAIN DRY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 1015 PM UPDATE... WEAK SECONDARY FRONT CONTINUES TO SINK SOUTH ACROSS THE REGION THIS EVENING WITH UPSTREAM OBSERVATIONS AT ART AND GTB CLEARLY SHOWING A WINDSHIFT TO THE NORTH. IR SATELLITE IMAGERY A FAIRLY RAPID DECREASE IN CLOUDS ALONG THIS FEATURE WITH LOSS OF DAYTIME HEATING AND SKY GRIDS HAVE BEEN ADJUSTED ACCORDINGLY. SOME CONCERN STILL LINGERS FOR PATCHY FROST ACROSS THE CHEMUNG BASIN AFTER 06Z BUT OVERALL CONFIDENCE REMAINS MARGINAL AS TEMPS HAVE BEEN SLOW TO COOL THIS EVENING WITH FRONT STILL TO THE NORTH THIS HR. SINCE WE CANNOT RULE IT OUT HOWEVER...A PATCHY FROST MENTION HAS BEEN MAINTAINED FOR NOW. NO OTHER ADJUSTMENTS NEEDED AT THIS TIME. 715 PM UPDATE... FCST IN GREAT SHAPE THIS EVENING...NO SIGNIFICANT CHANGES NEEDED AT THE PRESENT TIME. VIS SATELLITE SHOTS STILL SHOWING A FAIRLY WELL DEFINED AND NARROW CU FIELD ALONG A SOUTHWARD SAGGING SECONDARY COLD FRONT WHICH NOW STRETCHES FROM NEAR WATERTOWN/FT. DRUM...WEST THROUGH KINGSTON ONTARIO. FEATURE WILL CONTINUE DIVING SOUTH THROUGH THE FCST AREA THIS EVENING BEFORE CLEARING THE CWA SHORTLY AFTER 06Z. ATTENTION THROUGH THE OVERNIGHT WILL REMAIN FOCUSED ON POSSIBLE FROST POTENTIAL ACROSS THE CHEMUNG RVR VLY. WILL CONTINUE TO MONITOR TRENDS HOWEVER LATEST MODEL GUIDANCE CONTINUES TO SUGGEST FAIRLY DRY LOW-LEVEL CONDITIONS WHICH SHOULD KEEP FROST DEVELOPMENT RATHER ISOLATED AT BEST. 3 PM UPDATE... JUST A FEW FAIR WEATHER CUMULUS AT 8-10 KFT AGL THIS AFTERNOON WHICH WILL QUICKLY DISSIPATE. AS EXPECTED...INVERTED-V PROFILE HAS MIXED DOWN FAIRLY GUSTY WINDS ALONG WITH VERY DRY AIR AND THUS A MAXIMIZED DIURNAL RANGE. WIDESPREAD 70S WITH SOME LOCATIONS SUCH AS ELMIRA EVEN TOUCHING 80 DEGREES FOR TEMPERATURES...AND HUMIDITY VALUES AREAWIDE HAVE MANAGED MAINLY 20S PERCENT RANGE. SECONDARY COLD FRONT WILL DIP ACROSS THE AREA TONIGHT...AND WITH SUCH LIMITED MOISTURE...NO PRECIPITATION EXPECTED WHATSOEVER. LOSS OF DIURNAL HEATING WILL ERODE MUCH OF THE CLOUD COVER CURRENTLY BEHIND THE FRONT IN CENTRAL ONTARIO AND QUEBEC. HOWEVER...WRFARW AND RUC SOUNDINGS SHOW THAT BAND OF MOISTURE 4-5 KFT AGL WILL ADVECT IN IMMEDIATELY ALONG THE FRONT ITSELF. SKY GRIDS THUS REFLECT SOME CLOUDS DROPPING ACROSS THE NORTHERN TO CENTRAL PART OF THE AREA OVERNIGHT...BEFORE MIXING OUT IN DRY AIR FRIDAY MORNING. EXPECTING MAINLY 40S FOR LOWS TONIGHT...BUT FAIR AMOUNT OF RADIATIONAL COOLING WILL LEAD THE TYPICAL COLDER DRAINAGE-PRONE SPOTS GETTING INTO THE 30S. PATCHY FROST HAS BEEN ADDED TO A COUPLE SPOTS IN THE WEATHER GRIDS IN CENTRAL SOUTHERN TIER OF NY TO BRADFORD COUNTY PA...BUT NOT EXPECTING ENOUGH TO WARRANT FROST ADVISORY. THE EVENING SHIFT WILL MONITOR THIS CLOSELY IN CASE EXPECTATIONS SHOULD CHANGE. && .SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/... 315 PM UPDATE... HIGH PRESSURE IN CHARGE FRIDAY INTO FRIDAY NIGHT WITH DRY WEATHER AND TEMPERATURES RIGHT AROUND CLIMATOLOGY. BAROCLINIC ZONE SETS UP JUST SOUTH AND SOUTHWEST OF OUR VICINITY OVER THE WEEKEND. WHAT HAS BECOME CLEARER IS THAT CLOUDS WILL DEVELOP AND THICKEN COURTESY OF MOISTENING BAROCLINIC LIFT...ESPECIALLY CENTRAL TO SOUTHERN ZONES. HOWEVER...WITH DRY AIR IN THE LOW LEVELS AND FAIRLY WEAK WAVES ALOFT...PRECIPITATION CHANCES ARE MUCH MORE IFFY. ALSO...AS HIGH PRESSURE SITUATES OFFSHORE INTO SUNDAY...STABILIZING COOL ONSHORE SOUTHEAST FLOW WILL DIP TEMPERATURES ESPECIALLY FROM TWIN TIERS SOUTHWARD. EVER SLOW SLIGHT YET VERY ELEVATED INSTABILITY ALSO IS SUGGESTED BY THE SOUNDINGS AT LEAST FOR LATE SATURDAY INTO SATURDAY NIGHT. OVERALL NOT VERY BULLISH ON RAIN CHANCES BUT HAVE TO RESPECT PRESENCE OF BAROCLINIC ZONE AND MOISTURE...WHICH SOMETIMES YIELDS SURPRISES THAT MODELS CAN STRUGGLE WITH. FOR NOW...WENT WITH SLIGHT TO LOW CHANCE POPS MAINLY WESTERN/SOUTHERN ZONES LATE SATURDAY...THEN SPREADING OVER REMAINDER OF THE AREA SATURDAY NIGHT INTO SUNDAY. && .LONG TERM /MONDAY THROUGH THURSDAY/... MEDIUM RANGE MODELS ARE IN FAIR AGREEMENT THROUGH THIS PERIOD INDICATING AN UPPER LEVEL RIDGE WILL BUILD OVER THE NORTHEAST INITIALLY AS AN UPPER LEVEL TROF DIGS INTO THE NORTHERN PLAINS. TOWARD THE END OF THE PERIOD THE RIDGE WILL FLATTEN THEN AN UPPER LEVEL TROF DROPPING THROUGH EASTERN CANADA WILL MOVE INTO THE NORTHEAST. AT THE SFC, SUNDAY NIGHT INTO MONDAY, HIGH PRES OFF THE NEW ENGLAND COAST AND A WARM FRONT DRAPED OVER THE MID ATLANTIC WILL PROVIDE A SOMEWHAT MOIST RETURN FLOW BRINGING PRIMARILY A SLIGHT CHC FOR SHOWERS OVER CENTRAL NY AND CHC FOR NE PA. FOR THE REMAINDER OF THE PERIOD WILL CONTINUE TO CARRY CHC POPS FOR SHOWERS AND THUNDERSTORMS, AS SFC LOW PRES MOVING INTO THE WESTERN LAKES WILL BRING A WARM FRONT TO THE VCNTY THROUGH TUESDAY NIGHT WITH THE TRAILING COLD FRONT MOVING THROUGH WED/WED NIGHT. WILL ADVERTISE CHC/SLIGHT CHC POPS ON THURSDAY, POST FRONTAL AS UPPER LEVEL TROF RESIDES OVER REGION. TEMPS THROUGH THE PERIOD WILL RUN 5-10 DEGREES ABOVE NORMAL WITH A RETURN TO MORE SEASONAL TEMPS BY THURSDAY. && .AVIATION /07Z FRIDAY THROUGH TUESDAY/... NW FLOW OF DRY AIR WILL CONT THRU THE TAF PD KEEPING VFR CONDS FOR ALL SITES. LGT WINDS THIS MRNG WILL BECOME NW ARND 10 KTS TODAY...BUT WILL NOT BE AS GUSTY AS THU. THE WILL BECOME LGT ONCE AGAIN AFTN DARK FRI AS WE LOSE MIXING. OUTLOOK... SATURDAY THROUGH TUESDAY...PRIMARILY VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJP NEAR TERM...DJP SHORT TERM...DJP LONG TERM...RRM AVIATION...DGM/JAB
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
159 AM EDT FRI MAY 17 2013 .SYNOPSIS... DRY CONDITIONS WILL PERSIST THROUGH AT LEAST SATURDAY MORNING. CLOUDS WILL DEVELOP OVER THE WEEKEND AS A FRONTAL ZONE SETS UP NEAR OUR VICINITY. SOME AREAS MAY GET A FEW LIGHT SHOWERS LATE SATURDAY INTO SUNDAY...WITH BEST CHANCES IN NORTHEAST PENNSYLVANIA. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 1015 PM UPDATE... WEAK SECONDARY FRONT CONTINUES TO SINK SOUTH ACROSS THE REGION THIS EVENING WITH UPSTREAM OBSERVATIONS AT ART AND GTB CLEARLY SHOWING A WINDSHIFT TO THE NORTH. IR SATELLITE IMAGERY A FAIRLY RAPID DECREASE IN CLOUDS ALONG THIS FEATURE WITH LOSS OF DAYTIME HEATING AND SKY GRIDS HAVE BEEN ADJUSTED ACCORDINGLY. SOME CONCERN STILL LINGERS FOR PATCHY FROST ACROSS THE CHEMUNG BASIN AFTER 06Z BUT OVERALL CONFIDENCE REMAINS MARGINAL AS TEMPS HAVE BEEN SLOW TO COOL THIS EVENING WITH FRONT STILL TO THE NORTH THIS HR. SINCE WE CANNOT RULE IT OUT HOWEVER...A PATCHY FROST MENTION HAS BEEN MAINTAINED FOR NOW. NO OTHER ADJUSTMENTS NEEDED AT THIS TIME. 715 PM UPDATE... FCST IN GREAT SHAPE THIS EVENING...NO SIGNIFICANT CHANGES NEEDED AT THE PRESENT TIME. VIS SATELLITE SHOTS STILL SHOWING A FAIRLY WELL DEFINED AND NARROW CU FIELD ALONG A SOUTHWARD SAGGING SECONDARY COLD FRONT WHICH NOW STRETCHES FROM NEAR WATERTOWN/FT. DRUM...WEST THROUGH KINGSTON ONTARIO. FEATURE WILL CONTINUE DIVING SOUTH THROUGH THE FCST AREA THIS EVENING BEFORE CLEARING THE CWA SHORTLY AFTER 06Z. ATTENTION THROUGH THE OVERNIGHT WILL REMAIN FOCUSED ON POSSIBLE FROST POTENTIAL ACROSS THE CHEMUNG RVR VLY. WILL CONTINUE TO MONITOR TRENDS HOWEVER LATEST MODEL GUIDANCE CONTINUES TO SUGGEST FAIRLY DRY LOW-LEVEL CONDITIONS WHICH SHOULD KEEP FROST DEVELOPMENT RATHER ISOLATED AT BEST. 3 PM UPDATE... JUST A FEW FAIR WEATHER CUMULUS AT 8-10 KFT AGL THIS AFTERNOON WHICH WILL QUICKLY DISSIPATE. AS EXPECTED...INVERTED-V PROFILE HAS MIXED DOWN FAIRLY GUSTY WINDS ALONG WITH VERY DRY AIR AND THUS A MAXIMIZED DIURNAL RANGE. WIDESPREAD 70S WITH SOME LOCATIONS SUCH AS ELMIRA EVEN TOUCHING 80 DEGREES FOR TEMPERATURES...AND HUMIDITY VALUES AREAWIDE HAVE MANAGED MAINLY 20S PERCENT RANGE. SECONDARY COLD FRONT WILL DIP ACROSS THE AREA TONIGHT...AND WITH SUCH LIMITED MOISTURE...NO PRECIPITATION EXPECTED WHATSOEVER. LOSS OF DIURNAL HEATING WILL ERODE MUCH OF THE CLOUD COVER CURRENTLY BEHIND THE FRONT IN CENTRAL ONTARIO AND QUEBEC. HOWEVER...WRFARW AND RUC SOUNDINGS SHOW THAT BAND OF MOISTURE 4-5 KFT AGL WILL ADVECT IN IMMEDIATELY ALONG THE FRONT ITSELF. SKY GRIDS THUS REFLECT SOME CLOUDS DROPPING ACROSS THE NORTHERN TO CENTRAL PART OF THE AREA OVERNIGHT...BEFORE MIXING OUT IN DRY AIR FRIDAY MORNING. EXPECTING MAINLY 40S FOR LOWS TONIGHT...BUT FAIR AMOUNT OF RADIATIONAL COOLING WILL LEAD THE TYPICAL COLDER DRAINAGE-PRONE SPOTS GETTING INTO THE 30S. PATCHY FROST HAS BEEN ADDED TO A COUPLE SPOTS IN THE WEATHER GRIDS IN CENTRAL SOUTHERN TIER OF NY TO BRADFORD COUNTY PA...BUT NOT EXPECTING ENOUGH TO WARRANT FROST ADVISORY. THE EVENING SHIFT WILL MONITOR THIS CLOSELY IN CASE EXPECTATIONS SHOULD CHANGE. && .SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY/... 315 PM UPDATE... HIGH PRESSURE IN CHARGE FRIDAY INTO FRIDAY NIGHT WITH DRY WEATHER AND TEMPERATURES RIGHT AROUND CLIMATOLOGY. BAROCLINIC ZONE SETS UP JUST SOUTH AND SOUTHWEST OF OUR VICINITY OVER THE WEEKEND. WHAT HAS BECOME CLEARER IS THAT CLOUDS WILL DEVELOP AND THICKEN COURTESY OF MOISTENING BAROCLINIC LIFT...ESPECIALLY CENTRAL TO SOUTHERN ZONES. HOWEVER...WITH DRY AIR IN THE LOW LEVELS AND FAIRLY WEAK WAVES ALOFT...PRECIPITATION CHANCES ARE MUCH MORE IFFY. ALSO...AS HIGH PRESSURE SITUATES OFFSHORE INTO SUNDAY...STABILIZING COOL ONSHORE SOUTHEAST FLOW WILL DIP TEMPERATURES ESPECIALLY FROM TWIN TIERS SOUTHWARD. EVER SLOW SLIGHT YET VERY ELEVATED INSTABILITY ALSO IS SUGGESTED BY THE SOUNDINGS AT LEAST FOR LATE SATURDAY INTO SATURDAY NIGHT. OVERALL NOT VERY BULLISH ON RAIN CHANCES BUT HAVE TO RESPECT PRESENCE OF BAROCLINIC ZONE AND MOISTURE...WHICH SOMETIMES YIELDS SURPRISES THAT MODELS CAN STRUGGLE WITH. FOR NOW...WENT WITH SLIGHT TO LOW CHANCE POPS MAINLY WESTERN/SOUTHERN ZONES LATE SATURDAY...THEN SPREADING OVER REMAINDER OF THE AREA SATURDAY NIGHT INTO SUNDAY. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... MEDIUM RANGE MODELS ARE IN FAIR AGREEMENT THROUGH THIS PERIOD INDICATING AN UPPER LEVEL RIDGE WILL BUILD OVER THE NORTHEAST INITIALLY AS AN UPPER LEVEL TROF DIGS INTO THE NORTHERN PLAINS. TOWARD THE END OF THE PERIOD THE RIDGE WILL FLATTEN THEN AN UPPER LEVEL TROF DROPPING THROUGH EASTERN CANADA WILL MOVE INTO THE NORTHEAST. AT THE SFC, SUNDAY NIGHT INTO MONDAY, HIGH PRES OFF THE NEW ENGLAND COAST AND A WARM FRONT DRAPED OVER THE MID ATLANTIC WILL PROVIDE A SOMEWHAT MOIST RETURN FLOW BRINGING PRIMARILY A SLIGHT CHC FOR SHOWERS OVER CENTRAL NY AND CHC FOR NE PA. FOR THE REMAINDER OF THE PERIOD WILL CONTINUE TO CARRY CHC POPS FOR SHOWERS AND THUNDERSTORMS, AS SFC LOW PRES MOVING INTO THE WESTERN LAKES WILL BRING A WARM FRONT TO THE VCNTY THROUGH TUESDAY NIGHT WITH THE TRAILING COLD FRONT MOVING THROUGH WED/WED NIGHT. WILL ADVERTISE CHC/SLIGHT CHC POPS ON THURSDAY, POST FRONTAL AS UPPER LEVEL TROF RESIDES OVER REGION. TEMPS THROUGH THE PERIOD WILL RUN 5-10 DEGREES ABOVE NORMAL WITH A RETURN TO MORE SEASONAL TEMPS BY THURSDAY. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... NW FLOW OF DRY AIR WILL CONT THRU THE TAF PD KEEPING VFR CONDS FOR ALL SITES. LGT WINDS THIS MRNG WILL BECOME NW ARND 10 KTS TODAY...BUT WILL NOT BE AS GUSTY AS THU. THE WILL BECOME LGT ONCE AGAIN AFTN DARK FRI AS WE LOSE MIXING. OUTLOOK... SATURDAY THROUGH TUESDAY...PRIMARILY VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MDP NEAR TERM...CMG/MDP SHORT TERM...MDP LONG TERM...RRM AVIATION...DGM/JAB
AREA FORECAST DISCUSSION
NWS BISMARCK ND
350 AM CDT FRI MAY 17 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 349 AM CDT FRI MAY 17 2013 THE MAIN CONCERN FOR TODAY INTO TONIGHT WILL BE THE CHANCE OF THUNDERSTORMS AND POTENTIAL SEVERE WEATHER. EARLY MORNING RADAR MOSAIC SHOWED ISOLATED SHOWERS FROM SOUTHWEST NORTH DAKOTA INTO NORTHWEST MINNESOTA. MUCH OF THIS ACTIVITY DEVELOPED IN AN AREA OF H85 WARM AIR ADVECTION THAT HAS BEEN MOVING FROM SOUTH TO NORTH ACROSS THE REGION. THE STRONGEST WARM AIR ADVECTION SHIFTS NORTH BY AFTERNOON AS SOUTHWESTERLY FLOW ALOFT BRINGS A SERIES OF WAVES ACROSS THE STATE. WILL MAINTAIN FAIRLY HIGH POPS TODAY...ESPECIALLY IN THE NORTH AND WEST WHERE THE MAJORITY OF MODEL SOLUTIONS FAVOR THE HIGHER PRECIPITATION CHANCES. THE FOCUS THEN TURNS FARTHER SOUTH AS SURFACE LOW PRESSURE GATHERS IN EAST CENTRAL WYOMING. A WARM FRONT STRETCHING OUT OF THE LOW INTO SOUTHERN SOUTH DAKOTA IS EXPECTED TO LIFT NORTH TONIGHT...BRINGING INCREASING CHANCES OF SHOWERS AND THUNDERSTORMS TO CENTRAL AND WESTERN NORTH DAKOTA. CAN NOT RULE OUT AN ISOLATED SEVERE STORM LATE THIS AFTERNOON / EVENING ACROSS THE SOUTHERN PART OF THE FORECAST AREA WHERE INSTABILITY WILL BE GREATEST. THE SPC DAY 1 SEVERE WEATHER OUTLOOK KEEPS THE SLIGHT RISK SOUTH OF THE FORECAST AREA...HOWEVER THE 5 PERCENT PROBABILITIES FOR SEVERE HAIL / WIND ARE DRAWN SOUTH OF I-94 INTO SOUTHERN NORTH DAKOTA WHICH APPEARS REASONABLE. TEMPERATURES TODAY WILL BE TRICKY DUE TO THE CLOUDS AND RAIN. WILL GENERALLY STAY ON THE COOL SIDE OF GUIDANCE WHICH SUGGESTS MID 60S NORTH TO LOWER 70S SOUTH. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 349 AM CDT FRI MAY 17 2013 THE MAIN FORECAST ISSUES THROUGH THE LONG TERM PERIOD ARE CONVECTIVE TRENDS...AND POTENTIAL FOR PROLONGED MODERATE TO HEAVY RAIN AND SOME SEVERE WEATHER ON SATURDAY. THE LATEST 17/00Z MODEL RUNS HAVE SOME SIGNIFICANT DIFFERENCE IN THE PROGRESSION OF A CLOSED UPPER LOW THROUGH THE REGION THROUGH EARLY NEXT WEEK. THE NAM IS AMONG THE FARTHEST WEST...WHILE THE GFS FAVORS A FASTER...MORE EASTERLY PATH. THE ECMWF REPRESENTS A REASONABLE COMPROMISE...AND WOULD KEEP SHOWERS AROUND INTO TUESDAY BEFORE PUSHING EAST. THE FAVORED PERIOD FOR SEVERE WEATHER WILL BE SATURDAY...WITH SOUTHWEST FLOW ALOFT AND A WARM FRONT NOSING INTO THE SOUTHEAST PORTION OF THE FORECAST AREA. SPC CONTINUES TO HAVE THE SOUTHEAST OUTLOOKED IN SLIGHT RISK FOR DAY 2. BUFR SOUNDINGS SUGGEST STORMS WILL DEVELOP RELATIVELY EARLY IN THE DAY. AM EXPECTING SOME STRONG TO SEVERE STORMS WITH LARGE HAIL/STRONG WIND GUSTS THE PRIMARY THREATS. STRONG MOISTURE TRANSPORT INTO THE BOUNDARY WILL CONTINUE THROUGH SATURDAY NIGHT AS A DECENT SHORT WAVE TROUGH MOVES THROUGH EASTERN NORTH DAKOTA. THE SEVERE WEATHER THREAT DIMINISHES SUNDAY...BUT MODERATE TO LOCALLY HEAVY RAIN IS EXPECTED TO CONTINUE OVER MUCH OF WESTERN AND CENTRAL NORTH DAKOTA. THIS SCENARIO WILL LIKELY CONTINUE MONDAY...BEFORE SHOWERS TAPER OFF IN COVERAGE AND INTENSITY ON TUESDAY. TOTAL RAINFALL AMOUNTS OF 1 TO 3 ARE EXPECTED THROUGH THE PERIOD...WITH AMOUNTS AROUND 4 INCHES POSSIBLE...ESPECIALLY IN THE JAMES RIVER VALLEY. CONDITIONS ARE SUCH THAT SOILS CAN ABSORB SIGNIFICANT RAINFALL. THUS...SIGNIFICANT RISES ON MAIN STEM RIVERS SUCH AS THE SOURIS AND JAMES ARE NOT EXPECTED. HOWEVER...ENHANCED RAINFALL RATES OR SEVERAL ROUNDS OF STORMS COULD PRODUCE LOCALIZED RUNOFF...LEADING TO RISES ON SMALL CREEKS AND STREAMS...AND POSSIBLY FLASH FLOODING. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1244 AM CDT FRI MAY 17 2013 MVFR / IFR CEILINGS CONTINUE TO SPREAD INTO PARTS OF CENTRAL AND WESTERN NORTH DAKOTA EARLY THIS MORNING. THE WESTERN PART OF THE STATE APPEARS FAVORED FOR THE LOWEST CEILINGS WITH THE 17.00Z NAM SHOWING THE BEST LOW LEVEL SATURATION IN THAT REGION. RAIN CHANCES REMAIN DIFFICULT TO PINPOINT WITH ENOUGH SPREAD IN MODEL SOLUTIONS TO KEEP CONFIDENCE FAIRLY LOW IN SPECIFIC TIMING. THE 17.03Z RAP STILL FAVORS THE NORTH THIS MORNING IN AN AREA OF H85 WARM AIR ADVECTION. THIS IS GENERALLY IN LINE WITH CURRENT RADAR TRENDS...SO WILL CONFINE ANY SHOWERS THIS MORNING TO KMOT AND KISN. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM/AVIATION...CK LONG TERM...RP KINNEY
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1246 AM CDT FRI MAY 17 2013 .UPDATE... ISSUED AT 1244 AM CDT FRI MAY 17 2013 REGIONAL RADAR MOSAIC SHOWS ISOLATED TO SCATTERED SHOWERS ACROSS NORTH CENTRAL AND NORTHEAST NORTH DAKOTA. THIS APPEARS TO LINE UP WITH AN AREA OF H85 WARM AIR ADVECTION SHOWN BY THE 17.03Z RAP. THE STRONGEST WARM AIR ADVECTION IS FORECAST TO BE ACROSS NORTHERN PARTS OF THE STATE EARLY THIS MORNING...SO WILL HAVE THE HIGHEST POPS IN THAT REGION. INSTABILITY REMAINS LIMITED THIS MORNING...SO ANY THUNDER CHANCES SHOULD BE ISOLATED AT BEST. UPDATE ISSUED AT 1016 PM CDT THU MAY 16 2013 ADJUSTED EVENING POPS DOWNWARD BASED ON CURRENT RADAR OBS/TRENDS. OTHERWISE...NOT TOO MANY CHANGES WERE MADE TO THE ONGOING FORECAST. THE UPDATED GRIDDED AND TEXT PRODUCTS HAVE BEEN SENT. UPDATE ISSUED AT 718 PM CDT THU MAY 16 2013 REGIONAL RADAR TRENDS INDICATE NUMEROUS SHOWERS ACROSS THE JAMES RIVER BASIN CONTINUING TO PUSH EAST OF THE CWA THIS EVENING. WITH THE ATMOSPHERE PRETTY WELL WORKED OVER...DECREASED POPS WEST AND CENTRAL THROUGH THE REMAINDER OF THE EVENING HOURS. HOWEVER...SHORT RANGE MODEL GUIDANCE CONTINUES TO PROG INCREASING PRECIP CHANCES AFTER MIDNIGHT AS AN UPPER WAVE APPROACHES FROM THE SOUTHWEST. SHOWALTER INDICES INDICATE THUNDER POTENTIAL DEVELOPING ACROSS SOUTHWESTERN NORTH DAKOTA AFTER MIDNIGHT. AS A RESULT...REMOVED THUNDER AREAWIDE TONIGHT AND ONLY INDICATED ISOLATED THUNDER SOUTHWEST DEVELOPING AFTER MIDNIGHT. UPDATED THE HOURLY SENSIBLE WEATHER GRIDS BASED ON CURRENT OBS/TRENDS. THE UPDATED GRIDDED AND TEXT PRODUCTS HAVE BEEN SENT. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 300 PM CDT THU MAY 16 2013 LATEST WATER VAPOR IMAGERY SHOWS A SOUTHWEST FLOW INTO NORTH DAKOTA AHEAD OF AN UPPER TROUGH WHICH IS SLIDING INTO THE NORTHWEST COAST. FOR THE NEAR TERM...THROUGH THURSDAY EVENING...CATEGORICAL POPS WILL CONTINUE FROM BLAT TO MCCLUSKY INTO BISMARCK AND AREAS TO THE EAST AS A SHORTWAVE PROPAGATES THROUGH. THERE IS A BREAK IN THE CLOUDS AND PRECIPITATION IN THE FAR WEST WITH MORE SHORTWAVES MOVING INTO CENTRAL MONTANA. THESE WILL MOVE THROUGH TONIGHT INTO FRIDAY GENERATING ISOLATED TO SCATTERED SHOWERS. BEST CHANCE FOR AN ISOLATED THUNDERSTORM WILL RESIDE IN THE WEST AND SOUTH INTO TONIGHT. LATEST VISIBLE IMAGERY SHOWS SOME CLEARING IN THE WEST WITH CLOUDS BEGINNING TO BILLOW UP IN NORTHEAST MONTANA. FOR FRIDAY...SOME INSTABILITY CONTINUES IN THE SOUTHWEST AND FAR SOUTH CENTRAL FOR A MENTION OF THUNDERSTORMS...OTHERWISE SCATTERED SHOWERS WILL GENERALLY BE THE RULE. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 300 PM CDT THU MAY 16 2013 A BROADENING UPPER LEVEL LOW POSITIONED OVER THE WESTERN CONUS EARLY THE EXTENDED WILL ALLOW FOR MOIST SOUTHWESTERLY FLOW TO CONTINUE ACROSS THE NORTHERN PLAINS SATURDAY INTO SUNDAY. AS THIS BROAD UPPER LEVEL TROUGH SLOWLY SHIFTS EAST AND OVER THE REGION LATE SUNDAY AND EARLY MONDAY THE FLOW WILL BECOME SOUTHERLY AS THE UPPER LEVEL TROUGH CLOSES OFF OVER THE DAKOTAS. IT WILL REMAIN OVERHEAD MONDAY AND TUESDAY BEFORE MOVING EAST THEREAFTER. 12Z GFS/GEM/NAM/ECWMF ARE IN GOOD AGREEMENT REGARDING THIS PATTERN...BEFORE SOLUTIONS DIVERGE LATE IN THE EXTENDED AS THE UPPER LEVEL LOW MOVES EAST. THE MAIN ISSUE FOR THE EXTENDED WILL BE THE POTENTIAL FOR HEAVY RAIN THROUGH EARLY NEXT WEEK. THERE IS DECENT AGREEMENT BETWEEN THE 12Z MODEL RUNS REGARDING THE PLACEMENT AND AMOUNT OF PRECIPITATION ACROSS THE AREA...WITH THE HEAVIEST AMOUNTS FOCUSED ON THE JAMES RIVER VALLEY AND POINTS EAST. A SECOND AREA OF HEAVY PRECIPITATION MAY BE POSSIBLE ACROSS THE NORTHWEST. HOWEVER...THERE IS A BIT MORE UNCERTAINTY FOR THE NORTHWEST AREA. IN ADDITION...THE 12Z GFS AND NAM CONTINUE TO PLACE PRECIPITABLE WATER VALUES OF 1.30 TO 1.50 INCHES ACROSS THE EASTERN TWO THIRDS OF NORTH DAKOTA SATURDAY THROUGH EARLY SUNDAY MORNING. ACCORDING TO PW CLIMATOLOGY...THESE FORECAST VALUES WILL BE IN THE 99TH PERCENTILE TO THE HIGHEST EVER OBSERVED FOR THE MONTH OF MAY. CONFIDENCE IS INCREASING FOR 1 TO 2 INCHES (WITH LOCALLY HIGHER AMOUNTS ACROSS THE JAMES RIVER VALLEY) OF RAINFALL THROUGH SUNDAY EVENING. ADDITIONAL LIGHT TO MODERATE RAIN WILL CONTINUE THROUGH TUESDAY AS THE UPPER LEVEL LOW IS OVERHEAD...BRINGING POTENTIAL RAINFALL TOTALS THROUGH TUESDAY INTO THE 2 TO 4 INCH RANGE. THIS WILL HAVE TO BE MONITORED CLOSELY OVER THE NEXT FEW DAYS AS POTENTIAL HYDRO ISSUES FOR THE JAMES RIVER MAY COME INTO PLAY. ALSO...THIS HEAVY RAIN EVENT WILL POTENTIALLY ALLEVIATE THE RAINFALL DEFICITS OBSERVED SO FAR FOR MAY. REGARDING THE POTENTIAL FOR SEVERE WEATHER...THE BEST CHANCES FOR ANY SEVERE WEATHER WILL COME SATURDAY AFTERNOON THROUGH EARLY SUNDAY MORNING FOR LOCATIONS EAST OF STATE HIGHWAY 83 AND SOUTH OF INTERSTATE 94. ISOLATED SEVERE MAY BE POSSIBLE FOR THE SOUTHWEST LATE SATURDAY AFTERNOON AND EARLY EVENING. SUFFICIENT MOISTURE WILL BE PRESENT DUE TO PREVIOUS MOISTURE RECEIVED ON THURSDAY AND FRIDAY. BULK SHEAR VALUES WILL BE IN THE 40 TO 50 KT RANGE DURING THIS PERIOD...WITH ML CAPE IN THE 1000 TO 2000 J/KG RANGE FOR THE FAR SOUTH CENTRAL...AND 2000 TO 3000 J/LG VALUES ACROSS THE SOUTHERN JAMES RIVER VALLEY. MU CAPE VALUES WILL BE IN THE 1200 TO 3000 J/KG RANGE AS WELL. HOWEVER...THE MAIN LIMITING FACTOR WILL BE THE WARM AIR ALOFT...AS THE NAM/GFS BUFR SOUNDINGS FOR JMS/BIS DEPICT A DECENT CAP INVERSION. THIS MAY BE OVERCOME BY DAYTIME HEATING AND LARGE SCALE ASCENT ASSOCIATED WITH THE AFOREMENTIONED UPPER LEVEL TROUGH. BEYOND TUESDAY...THE UPPER LEVEL LOW WILL MOVE EAST AND IN ITS WAKE...UPPER LEVEL RIDING WILL COMMENCE. A PERIOD OF DRIER AND SEASONABLE TEMPERATURES ARE FORECAST FOR WEDNESDAY AND THURSDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1244 AM CDT FRI MAY 17 2013 MVFR / IFR CEILINGS CONTINUE TO SPREAD INTO PARTS OF CENTRAL AND WESTERN NORTH DAKOTA EARLY THIS MORNING. THE WESTERN PART OF THE STATE APPEARS FAVORED FOR THE LOWEST CEILINGS WITH THE 17.00Z NAM SHOWING THE BEST LOW LEVEL SATURATION IN THAT REGION. RAIN CHANCES REMAIN DIFFICULT TO PINPOINT WITH ENOUGH SPREAD IN MODEL SOLUTIONS TO KEEP CONFIDENCE FAIRLY LOW IN SPECIFIC TIMING. THE 17.03Z RAP STILL FAVORS THE NORTH THIS MORNING IN AN AREA OF H85 WARM AIR ADVECTION. THIS IS GENERALLY IN LINE WITH CURRENT RADAR TRENDS...SO WILL CONFINE ANY SHOWERS THIS MORNING TO KMOT AND KISN. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CK SHORT TERM...KS LONG TERM...LTH AVIATION...CK
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1150 PM CDT THU MAY 16 2013 .UPDATE... ISSUED AT 1150 PM CDT THU MAY 16 2013 BAND OF PRECIP ALONG HIGHWAY 2 HAS BEGUN TO DIMINISH AS 700MB FRONTOGENESIS HAS DECREASED. TRENDED DOWNWARD SLOWLY WITH POPS OVER THAT AREA FOR THE REST OF THE NIGHT. PRECIP TO OUR SOUTH HAS STAYED WELL CLEAR OF OUR SOUTHEASTERN BORDERS...SO LOWERED POPS UNTIL LATER IN THE DAY TOMORROW. MADE A FEW MINOR TWEAKS TO TEMPS AND WINDS. UPDATE ISSUED AT 937 PM CDT THU MAY 16 2013 SFC HIGH PRESSURE OVER ONTARIO AND A DEVELOPING LOW OVER CO/WY CONTINUES TO BRING NORTHEASTERLY WINDS THAT WILL SLOWLY SHIFT AROUND TO THE EAST LATER TONIGHT. STILL THINK THAT OUR LIGHT RAIN ALONG THE HIGHWAY 2 CORRIDOR WILL SLOWLY DIMINISH AS CONVECTION RAMPS UP FURTHER SOUTH. HOWEVER...PRECIP HAS MOVED A BIT FURTHER EAST THAN EARLIER EXPECTATIONS SO ADJUSTED POPS/WX ACCORDINGLY. KEPT LIKELIES GOING FOR THE REST OF THE EVENING AND THEN STARTED TO DROP THEM DOWN LATER TONIGHT. UPDATE ISSUED AT 646 PM CDT THU MAY 16 2013 BAND OF LIGHT RAIN CONTINUES FROM NEAR DEVILS LAKE TO THE CENTRAL RED RIVER VALLEY INTO NORTHWESTERN MINNESOTA...WITH SPRINKLES ELSEWHERE. THE NAM AND RAP ARE IN PRETTY GOOD AGREEMENT ON THIS ACTIVITY DIMINISHING LATER THIS EVENING AS THE COMPLEX OVER SD/MN GETS GOING AND ROBS MOISTURE. KEPT HIGH POPS IN THE NORTH THIS EVENING BEFORE TRANSITIONING TO BETTER PERCENTAGES IN THE SOUTH LATER ON TONIGHT. LOWERED TEMPS A BIT IN THE NORTHWEST AS READINGS HAVE ALREADY DROPPED INTO THE LOWER 50S AND THERE COULD BE SOME BREAKS IN THE CLOUDS LATER TONIGHT TO ALLOW IT TO GET DOWN INTO THE UPPER 40S. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 120 PM CDT THU MAY 16 2013 THE MAIN CHALLENGE WILL BE UPCOMING PROLONGED WET PATTERN TONIGHT INTO THE MIDDLE OF NEXT WEEK. MODELS ARE IN GOOD OVERALL AGREEMENT INITIALLY...WITH SOME DIFFERENCES BY NEXT WEEK. THE NAM/GFS ARE A GOOD COMPROMISE IN THE NEAR TERM. FOR TONIGHT...THERE WILL BE AN AREA OF SHOWERS MOVING FROM WEST TO EAST ACROSS THE AREA. THIS BAND OF SHOWERS IS BEING AIDED BY STRONG MID LEVEL OMEGA AND UPPER LEVEL DIVERGENCE...AS PWATS INCREASE TO AROUND 1 INCH. THERE SHOULD BE A BAND OF STRONGER CONVECTION SOUTH OF THE AREA OVERNIGHT...THAT SHOULD ROB THE DEEPER MOISTURE FROM OUR AREA. WE WILL INCREASE POPS THIS EVENING IN THE WEST INTO THE CENTRAL RED RIVER VALLEY WITH STRONGER ECHOES MOVING INTO THE AREA. FOR FRIDAY...WE SHOULD GET A BREAK IN THE LARGER SCALE SHOWERS WITH EASTERLY FLOW NEAR THE SFC INCREASING. WE WILL MAINTAIN A LOW CHANCE FOR SHOWERS THOUGH WITH PLENTY OF CLOUDS AND POSSIBLY A SUBTLE SHORTWAVE MOVING THROUGH. FOR FRIDAY NIGHT...A LLJ WILL DEVELOP IN SD AND MOVE INTO THE SOUTH OVERNIGHT EXPECT AN AREA OF SHOWERS AND THUNDERSTORMS TO MOVE INTO THE AREA...WITH THE BEST CHANCE FOR THUNDER IN THE SOUTH. THERE WILL BE SOME ELEVATED INSTABILITY WITH 850MB CAPE AROUND 1000 J/KG...SO A STRONG TO LOCALLY SEVERE STORM IS POSSIBLE. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 310 PM CDT THU MAY 16 2013 FOR SATURDAY THROUGH SUNDAY...A VERY ACTIVE WEATHER PATTERN IS EXPECTED. SHOWERS AND STORMS SHOULD BE ONGOING AT LEAST IN THE SOUTH SATURDAY MORNING. BY SATURDAY AFTERNOON AND EVENING...DEEP MOISTURE AND STRONG INSTABILITY SHOULD DEVELOP OVER SE ND...NEAR THE EDGE OF A STRONG CAPPING INVERSION. MLCAPES ARE PROGGED OVER 4000 J/KG INTO NC SD...AND AROUND 3000 J/KG IN SE ND. EXPECT STORMS TO DEVELOP QUICKLY IN SD ONCE THE CAP BREAKS...AND MOVE NORTH AND EAST INTO THE AREA SATURDAY NIGHT AND SUNDAY. SOME STORMS COULD BE SEVERE SATURDAY NIGHT INTO SUNDAY...BUT LOCALLY HEAVY RAIN IS POSSIBLE WITH PWATS RISING TO AROUND 1.5 INCHES OR EVEN A BIT HIGHER. WE HAVE ISSUED AN ESF FOR SOME LOCALIZED FLOODING POSSIBLE IF TRAINING ECHOES OCCUR WITH A PARALLEL UPPER BOUNDARY. SAME SCENARIO IN PLACE FOR EXTENDED...AFTER A WEEKEND OF RAIN AND THUNDERSTORMS...UPPER LOW LIKELY TO BE LOCATED OVER AN AREA ANYWHERE FROM SOUTHEAST NORTH DAKOTA TO IOWA. MOISTURE WILL STILL BE TRANSPORTED CYCLONICALLY AROUND THIS STACKED SYSTEM CONTINUING SHOWERS WITH THE POSSIBILITY OF SOME THUNDER. ORIENTATION OF BOUNDARY AND ASSOCIATED CONVECTIVE PARAMETERS MAKE MONDAY THE MORE LIKELY TIME FOR THUNDER ACTIVITY...LESS SO ON TUESDAY AND BY WEDNESDAY PRECIPITATION SHOULD BE MORE SHOWERY OR EVEN JUST SOME STRATIFORM RAIN. GOING POP FREE FINALLY BY THURSDAY AS AN OMEGA BLOCK DEVELOPS WITH NORTHERN PLAINS UNDER THE RIDGE PART OF THE BLOCK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1150 PM CDT THU MAY 16 2013 VFR CONDITIONS AND SLOWLY DIMINISHING LIGHT RA OVER KDVL...KGFK...AND KTVF WILL CONTINUE FOR THE REST OF THE NIGHT. SOME MVFR CONDITIONS WILL BE POSSIBLE AT KDVL AND POSSIBLY FURTHER EAST. WINDS WILL STAY EAST AROUND 10 KTS. && .HYDROLOGY... ISSUED AT 310 PM CDT THU MAY 16 2013 THE NORTHERN PORTION OF THE RED RIVER CONTINUES TO SEE RIVER LEVELS UNDERGO RECESSION AT DRAYTON AND PEMBINA. THIS IS THE LAST REMNANT OF THE SNOWMELT WATER SURGE CONTINUING TO MOVE NORTHWARD INTO CANADA. A PROLONGED PERIOD OF UNSETTLED WEATHER IS EXPECTED TO BEGIN THIS EVENING AND CONTINUE THROUGH TUESDAY. CUMULATIVE RAINFALL TOTALS OF 2 TO 4 INCHES ACROSS THE RED RIVER BASIN...WITH LOCALLY HIGHER AMOUNTS...WILL BE POSSIBLE BY TUESDAY MORNING. LOCALIZED FLASH FLOODING IS A POSSIBILITY OVER THE WEEKEND DUE TO TRAINING THUNDERSTORMS. IN ADDITION...DESPITE SOME RAINFALL INFILTRATION DUE TO PATCHY DRY TOPSOIL...ENOUGH RUNOFF MAY OCCUR TO CAUSE SOME SMALLER TRIBUTARIES TO RISE BACK ABOVE FLOOD STAGE NEXT WEEK. AS A RESULT...A HYDROLOGIC OUTLOOK HAS BEEN ISSUED TO HIGHLIGHT THE SITUATION. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...JR SHORT TERM...DK LONG TERM...WJB/DK AVIATION...JR HYDROLOGY...BRAMER
AREA FORECAST DISCUSSION...UPDATED
NWS NASHVILLE TN
1157 PM CDT THU MAY 16 2013 .UPDATE...FOR 06Z AVIATION DISCUSSION. && .AVIATION...06Z AVIATION DISCUSSION. UNCERTAINTIES...ACTUAL SHWRS/TSTMS LOCATION DEVELOPMENT...TRANSITIONAL TIMING FROM VFR/MVFR CEILINGS AND ACTUAL COVERAGE OF SHWRS/TSTMS 17/10Z-18/06Z. STILL EXPECTING OVERALL INCREASING INSTABILITY...MOISTURE...AND LIFTING MECHANISM THRU 18/06Z...ESPECIALLY AFTER 17/10Z...AND WILL CONTINUE WITH A GENERAL TREND OF VCSH THRU 17/11Z...TRANSITIONING TO CAT SHWRS/TSTMS 17/11Z-18/06Z...AS OPENING UPPER LEVEL LOW/UPPER LEVEL TROUGH MOVES ACROSS WRN COUNTIES AND THEN ACROSS REST OF MID STATE. STILL BELIEVE THAT ACTIVITY MAY BE MORE DIURNAL BASED ERN PORTIONS OF MID STATE AS OF 17/12Z-18/00Z AND THUS WILL CONTINUE WITH VCTS REMARKS AS LOCATION DEVELOPMENT UNCERTAIN THRU AT LEAST 18/00Z. CAT SHWRS/TSTMS ALL AREAS EXPECTED BETWEEN 18/00Z-18/06Z. && .PREV DISCUSSION.../ISSUED 658 PM CDT THU MAY 16 2013/ UPDATE... JUST ISOLATED SHOWER AND TSTM ACTIVITY THUS FAR ACROSS THE MID STATE THIS EVENING. BETTER COVERAGE OF SHOWERS AND TSTMS EXISTS BACK TO OUR WEST ACROSS AR. MODELS ARE IN AGREEMENT WITH THIS DEEPER AREA OF MOISTURE SPREADING EASTWARD AND REACHING WESTERN PORTIONS OF MIDDLE TN TOWARD SUNRISE. HRRR FURTHER SUPPORTS AN INCREASE IN OUR POPS OVERNIGHT FOR MAINLY OUR WESTERN AREAS. THUS...WILL GO AHEAD AND MODIFY THE WEATHER GRIDS AND SEPARATE THE OVERNIGHT GRIDS INTO TWO...00Z-06Z AND 06Z-12Z. WILL EXPAND THE LIKELY POPS OVER OUR WEST AND MOVE THE CHC CATEGORY A LITTLE FURTHER EAST AS WELL. REMAINDER OF FCST IS IN GOOD SHAPE. SEE NO REASON FOR ANY FURTHER MODS. UPDATES OUT SHORTLY. PREV DISCUSSION.../ISSUED 312 PM CDT THU MAY 16 2013/ SHORT TERM...RIDGE OF HIGH PRESSURE SITUATED EAST OF MIDDLE TENNESSEE THIS AFTERNOON, ALLOWING ADVECTION OF WARM, MOIST AIR TO TAKE PLACE. LATEST LAPS SOUNDING SHOWS INSTABILITY GRADUALLY INCREASING WITH AFTERNOON HEATING, BUT ATMOSPHERE BELOW 600 MB IS STILL LARGELY DRY. LOOK FOR SATURATION TO GRADUALLY TAKE PLACE LATER TONIGHT AS TOMORROW S A SHORTWAVE APPROACHES MIDDLE TENNESSEE FROM THE WEST AND BEGINS TO SPREAD CONVECTION ACROSS THE MID STATE. LOOK FOR MAINLY SCATTERED ACTIVITY WEST OF THE PLATEAU OVERNIGHT, WITH POP`S INCREASING TOMORROW. CENTER OF UPPER LOW MOVES INTO SOUTHWESTERN KENTUCKY BY TOMORROW AFTERNOON ACCOMPANIED BY A GOOD BAND OF LIFT OVER OUR WESTERN COUNTIES. THUS, HAVE GONE WITH CATEGORICAL POPS FOR THOSE AREAS TOMORROW, RANGING TO 50% POPS ALONG THE UPPER CUMBERLAND. SHORTWAVE CONTINUES SLOWLY EASTWARD FRIDAY NIGHT, WITH SHOWERS AND THUNDERSTORMS LIKELY AREA-WIDE. ATMOSPHERIC MOISTURE REMAINS DEEP ON SATURDAY, ESPECIALLY NORTH AND EAST, WHERE SHOWERS AND THUNDERSTORMS WILL REMAIN LIKELY. WESTERN AREAS SHOULD START TO DRY OUT BY LATE SATURDAY NIGHT, AS UPPER LOW CENTER MOVES TO NEAR SOUTHWEST VIRGINIA BY 12Z SUNDAY. RIDGE OF HIGH PRESSURE BUILDS IN OVER THE AREA EARLY NEXT WEEK, ALLOWING FOR MORE DAYTIME SUNSHINE AND SENDING DAYTIME HIGHS PUSHING INTO THE MIDDLE AND UPPER 80S BOTH MONDAY AND TUESDAY. LONG TERM...DURING THE MIDDLE TO LATTER PART OF NEXT WEEK, EXPECT UPPER RIDGE TO PUSH EAST, ALLOWING FOR A MOIST SOUTHWEST FLOW TO DEVELOP FROM THE SOUTHERN PLAINS AND LOWER MISSISSIPPI RIVER VALLEY UP ACROSS THE TENNESSEE AND OHIO RIVER VALLEYS. SHOWERS AND THUNDERSTORMS WILL PROBABLY BECOME LIKELY AGAIN BY WEDNESDAY, WITH AT LEAST SMALL CHANCES FOR SHOWERS AND THUNDERSTORMS LINGERING INTO THURSDAY AS WELL. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 31
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
354 AM CDT FRI MAY 17 2013 .DISCUSSION... ...A FEW SEVERE STORMS POSSIBLE ACROSS FAR WESTERN NORTH TEXAS BY EACH EVENING TODAY AND SATURDAY...THEN NORTH OF I-20 LATE SUNDAY... WEATHER FORECAST REMAINS CHALLENGING TODAY INTO THE WEEKEND. WE CONTINUED TO SEE A SUBTLE SURFACE BOUNDARY SITUATED ALONG/NORTH OF HWY 38 THIS MORNING AS EVIDENCED BY THE BACKED/LIGHTER EAST WINDS AND LOWER SURFACE DEW POINTS THIS MORNING...WHILE STRONGER SSE WINDS 10 TO 15 MPH WHERE OCCURRING FROM THE I-20 CORRIDOR INTO CENTRAL TEXAS. SOME PATCHY DENSE FOG WAS OCCURRING ALONG THE RED RIVER VALLEY...WHILE A SUBTLE DISTURBANCE WAS MOVING ACROSS WITHIN THE UPPER RIDGE OVER THE TOP OF THE AREA. SOME AC/ACCAS WAS NOTED ON INFRARED SATELLITE IMAGERY WITH STEEP LAPSE RATES ALOFT ON THE 00Z FWD SOUNDING AND MODELS. ISOLATED...ELEVATED/HIGH-BASED SHOWERS AND STORMS ARE POSSIBLE THIS MORNING MAINLY ALONG AND SOUTH OF THE I-20/I-30 CORRIDORS. LIGHTNING WILL BE THE MAIN THREAT WITH ACTIVITY THIS MORNING WITH VERY LITTLE IN THE WAY OF MEASURABLE RAINFALL EXPECTED. THE SURFACE DRYLINE AND ASSOCIATED LOW PRESSURE OVER FAR WEST TEXAS WILL CONTINUE TO DEEPEN AND SLIDE SLOWLY EAST TOWARD OUR FAR W/SW COUNTIES LATE THIS AFTERNOON/EVE. STRONG MIXING AND HEATING ALONG AND JUST AHEAD OF THIS FEATURE WILL HELP HIGHS SOAR WELL INTO THE 90S WITH A FEW AREAS TOPPING THE CENTURY MARK WEST OF I-35/I-35W. OUR CAPPING INVERSION WAS ELEVATED AND BASED ABOVE 800MB AND NOT OVERLY STOUT...SO DESPITE THE UPPER RIDGE ARRIVING OVERHEAD...FEEL THE HOT TEMPS WILL MAKE IT BREAKABLE. HIGH-RES WRF/ARW/AND HRRR MODELS ALL HINT AT ISOLATED STORM DEVELOPMENT JUST W/SW OF OUR CWA AT PEAK HEATING AND POTENTIALLY AFFECTING OUR FAR WSW COUNTIES BETWEEN 4 PM AND SUNSET. INSTABILITY WILL BE VERY HIGH WITH MODELS SHOWING 3500-5000 J/KG SBCAPE OR POSSIBLY MORE WITH VERY STEEP MID LEVEL LAPSE RATES OVER 8 DEG C/KM. ANY ISOLATED STORMS THAT OCCUR WILL LIKELY BE SEVERE WITH VERY LARGE HAIL AND DAMAGING DOWNBURSTS. DESPITE SURFACE DEW POINTS BEING NEAR 70 DEGREES...THE HOT TEMPERATURES WILL RESULT IN RELATIVELY HIGH BASES AND A LOWER TORNADO THREAT THAN A FEW DAYS AGO. WITH THE UPPER RIDGE OVERHEAD...STORMS WILL DIMINISH IN STRENGTH OR DISSIPATE RAPIDLY AROUND SUNSET WITH LOSS OF HEATING AND THE CAP INTENSIFYING QUICKLY BY LATE EVENING. THE UPPER RIDGE SHIFTS EAST OF THE AREA ON SATURDAY WITH LONGWAVE UPPER TROUGH SNAKING OVER THE ROCKIES INTO THE WESTERN HIGH PLAINS. THE DRYLINE WILL ACTUALLY MAKE A STRONGER PUSH TOWARD OUR FAR WESTERN COUNTIES BY EARLY EVENING SATURDAY WITH A LITTLE BETTER UPPER SUPPORT. INSTABILITY WILL BE VERY STRONG ONCE AGAIN WITH ISOLATED TO SCATTERED STRONG TO SEVERE STORMS EXPECTED MAINLY ALONG AND WEST OF HWY 281...THEN DIMINISHING QUICKLY AFTER SUNSET WITH THE CAP INTENSIFYING ONCE AGAIN. THE UPPER TROUGH DAMPENS OVER THE CONUS ON SUNDAY WITH STRONG WESTERLY FLOW ALOFT OCCURRING FROM THE RED RIVER VALLEY NORTH THROUGH THE CENTRAL PLAINS. HAVE MODIFIED BEST CHANCES TO OCCUR NORTH OF I-20 AND INTO THE RED RIVER VALLEY...WITH THE CAP BEING MUCH STRONGER OVER THE SOUTH. DIURNAL SEVERE WEATHER WILL BE POSSIBLE AGAIN...BUT CONFIDENCE IS LOWER FOR LATE SUNDAY DUE TO UNCERTAINTIES REGARDING CAP STRENGTH AND SOUTHERN EXTENT OF FORCING. THE BEST SURFACE FOCUS WILL BE ALONG A COLD FRONT THAT IS EXPECTED TO BE WELL TO THE NORTHWEST OF THE AREA AS WELL. OTHERWISE IN THE EXTENDED...STAYED WITH PERSISTENCE WITH THE PREVIOUS FORECAST WITH LOW POPS RETURNING BY MID WEEK WITH A COLD FRONT WEAKENING AND STALLING ACROSS THE NORTHWEST COUNTIES. A SHORTWAVE TROUGH WILL BE MOVING OVER THE CENTRAL AND SOUTHERN PLAINS AT THIS TIME AS WELL. IT IS TOO EARLY TO ASSESS ANY SEVERE WEATHER THREAT THIS FAR OUT...BUT WILL CONTINUE TO ASSESS THESE POSSIBILITIES IN THE COMING DAYS AHEAD. 05/ && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 89 72 93 72 88 / 10 10 5 10 10 WACO, TX 92 71 92 71 90 / 20 10 5 10 10 PARIS, TX 82 68 86 69 86 / 10 10 10 10 10 DENTON, TX 86 70 93 71 89 / 10 10 10 10 20 MCKINNEY, TX 84 69 91 69 88 / 10 10 5 10 10 DALLAS, TX 88 72 93 72 90 / 10 10 5 10 10 TERRELL, TX 89 69 90 70 89 / 10 10 5 10 10 CORSICANA, TX 91 70 91 70 89 / 20 10 5 10 10 TEMPLE, TX 91 70 91 71 89 / 10 10 10 10 10 MINERAL WELLS, TX 94 70 96 70 93 / 10 10 10 10 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 05/
FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND SATURDAY ISSUED AT 346 AM CDT FRI MAY 17 2013 FORECAST CONCERNS THIS PERIOD ON PCPN CHANCES THROUGH THE PERIOD. WARM FRONT EXTENDS EAST OUT OF NE INTO NORTHERN IL. ONGOING PCPN OVER IA/MN BORDER...NOW EDGING INTO WESTERN WI. CLOUDS HAVE KEPT TEMPS UP OVERNIGHT OVER MUCH OF CWA...WITH ONLY THE FAR NORTH FALLING INTO THE UPPER 30S. EASTERLY WINDS OVER WI...STILL USHERING IN DRY AIR WITH DEW POINTS IN THE 30S. THIS HAS SLOWED ADVANCE OF PCPN...THOUGH HIGH BASED...THE RETURNS ARE INCREASING OVER THE STATE. HAVE CONTINUED TREND OF EVENING FORECASTER TO SHIFT PCPN SOUTH INTO CENTRAL AND EAST CENTRAL WI LATER THIS MORNING...THEN SHIFT NORTH TONIGHT AND SAT AS WARM FRONT LIFTS NORTH/RIDGE BUILDS IN. HAVE TRENDED TOWARDS MESO MODELS LIKE HRRR FOR DAY 1 PCPN TRENDS. PCPN FOCUS ASSOCIATED WITH INCREASING ISENTROPIC LIFT/FGEN FORCING WITH 850 BAROCLINIC ZONE OVER STATE. HAVE STAYED WITH JUST SHOWER MENTION THROUGH TODAY AS INSTABILITY MISSING OVER EASTERN WI...BRINGING IN SLIGHT CHANCE LATER TONIGHT AND SATURDAY AS LOW LEVEL MOISTURE INCREASES AND STEEPER MID LEVEL LAPSE RATES SHIFT EAST. TEMPS TODAY TO BE HELD BACK BY CLOUDS AND EAST FLOW THUS STAYED WITH UPPER 50S AND LOWER 60S THROUGHOUT CWA. MAX TEMPS BACK TO NORMAL OR ABOVE ON SAT...EXCEPT EAST WITH CONTINUED EASTERLY COMPONENT. .LONG TERM...SATURDAY NIGHT THROUGH THURSDAY ISSUED AT 346 AM CDT FRI MAY 17 2013 THE MAIN CONCERN DURING THE LONG TERM IS TIMING PRECIPITATION INTO THE AREA. A FRONTAL BOUNDARY IS FORECAST TO PUSH NORTHEAST THROUGH WISCONSIN EARLY NEXT WEEK. SURFACE FLOW WILL BE OFF LAKE MICHIGAN BETWEEN HIGH PRESSURE TO THE EAST AND THE FRONT...BUT PRECIPITATION WILL MOVE IN AS THE FRONT PASSES AND THE SURFACE LOW TO THE WEST GETS CLOSER TO WISCONSIN. HAVE A DRY FORECAST FOR SATURDAY NIGHT BUT WENT WITH CHANCE POPS FOR CENTRAL AND NORTH CENTRAL WISCONSIN SUNDAY. HAVE AT LEAST A CHANCE OF SHOWERS AND THUNDERSTORMS GOING THROUGH THE MIDDLE OF NEXT WEEK AS THE SURFACE LOW AND UPPER LEVEL CYCLONE PASS TO THE EAST OF THE AREA. TEMPERATURES SHOULD REMAIN ABOVE NORMAL THROUGH THE EARLY PART OF NEXT WEEK BEFORE A SURFACE RIDGE MOVES INTO THE REGION BRINGING COOLER THAN NORMAL TEMPERATURES FOR THE LATTER HALF OF THE WEEK. && .AVIATION...FOR 06Z TAF ISSUANCE ISSUED AT 1034 PM CDT THU MAY 16 2013 VFR CONDITIONS THROUGH FRIDAY MORNING. MVFR CIGS WITH SHOWERS MAY BECOME MORE NUMEROUS MAINLY NORTH AND WEST OF THE FOX VALLEY LATE FRIDAY MORNING INTO THE AFTERNOON HOURS. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....TE LONG TERM......MG AVIATION.......TDH
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
900 AM MST FRI MAY 17 2013 .SYNOPSIS... A DRY PACIFIC COLD FRONT WILL MOVE ACROSS THE AREA TODAY...ACCOMPANIED BY BRIEF CLOUDINESS...GUSTY AFTERNOON WINDS...AND COOLER TEMPERATURES. A SLIGHTLY COOLER AIRMASS WILL SETTLE INTO THE REGION SATURDAY PROVIDING CLEAR SKIES WITH BELOW NORMAL TEMPERATURES. A WARMING TREND IS EXPECTED SUNDAY...WITH AFTERNOON TEMPERATURES WARMING BACK INTO 100 TO 103 DEGREE RANGE ON THE DESERTS NEXT MONDAY THROUGH THURSDAY. && .DISCUSSION... MID MORNING WATER VAPOR IMAGERY DEPICTS A TROUGH STRETCHING FROM BRITISH COLUMBIA TO BAJA CALIFORNIA...WITH QUITE A BIT OF MID LEVEL MOISTURE MOVING INTO SOUTHERN CALIFORNIA...ARIZONA...AND UTAH. CLOUD COVER HAS REALLY EXPANDED OVER THE PAST SEVERAL HOURS AS A 70KT UPPER JET HAS MOVED ONSHORE...LIKEWISE...PRECIPITABLE WATER PER BLENDED TPW IMAGERY HAS INCREASED AND IS NOW CLOSE TO 0.8 INCHES ALONG THE LOWER COLORADO RIVER VALLEY /APPROX 150 PERCENT OF NORMAL/. NOT SURPRISINGLY...RADAR BEGINNING TO SHOW SOME RETURNS ACROSS SOUTHEAST CALIFORNIA INTO WESTERN ARIZONA...HOWEVER SURFACE DEWPOINTS REMAIN IN THE LOW TO MID 40S. WITH DEWPOINTS FORECAST TO DROP SEVERAL MORE DEGREES LATER THIS AFTERNOON...HARD TO ENVISION MUCH /IF ANY/ MEASURABLE PRECIP WITH THIS TROUGH. 12Z NAM MODEL SOUNDINGS AND 14Z RAP DATA...ALONG WITH LATEST HRRR RUN AND HI-RES LOCAL MODEL SUITE INDICATE A CONSIDERABLE T/TD SPREAD BELOW 700MB ACROSS THE LOWER DESERTS ALL THE WAY THROUGH THIS EVENING. I INTRODUCED A CHANCE OF SPRINKLES INTO THE FORECAST FOR THE HIGHER ELEVATIONS OF SOUTHEAST CALIFORNIA AND SOUTH-CENTRAL ARIZONA THROUGH LATE AFTERNOON...BUT POPS WILL REMAIN AT 0. EVEN THE NORMALLY PESSIMISTIC SREF ADVERTISES 0 POPS ACROSS THE FORECAST AREA TODAY. WILL BE DIFFICULT TO OVERCOME THE VERY DRY BL. SOME BREEZINESS IS EXPECTED WITH THE TROUGH LATER THIS AFTERNOON COURTESY OF MODEST DRY ADVECTION. THE STRONGEST WINDS /30 MPH GUSTS/ WILL BE CONFINED TO THE NORMALLY WINDIER LOCATIONS OF SOUTHEAST CALIFORNIA AND THE LOWER COLORADO RIVER VALLEY ALTHOUGH CRITICAL FIRE WX/WIND ADVISORY THRESHOLDS SHOULD NOT BE REALIZED. TEMPS TODAY LOOKING ON TRACK SO FAR. BEST PERFORMING BIAS CORRECTED GUIDANCE SQUARELY POINTING AT 96 FOR A HIGH IN PHOENIX WITH SLIGHTLY COOLER VALUES TO THE WEST. SHOULD BE THE FIRST DAY SINCE SUNDAY BELOW THE CENTURY MARK. ONLY MINOR ADJUSTMENTS MADE TO THE INHERITED TEMPERATURE FORECAST. && .PREVIOUS DISCUSSION... SATURDAY THROUGH MONDAY... DRY NORTHWEST FLOW ALOFT WITH NEARLY CLOUDLESS SKIES ARE EXPECTED THIS PERIOD. ADDITIONAL COOLING IS FORECAST FOR SATURDAY...WARMING SUNDAY...THEN BACK INTO THE 100 TO 103 DEGREE RANGE ON THE DESERTS MONDAY. TUESDAY THROUGH THURSDAY... DRY WESTERLY FLOW ALOFT WITH ABOVE NORMAL TEMPERATURES ARE EXPECTED. && .AVIATION... SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...KSDL...SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA...INCLUDING KIPL AND KBLH... A LOW PRESSURE TROUGH WILL SKIRT BY TO THE NORTH TODAY WITH INCREASED MID AND HIGH CLOUDS THROUGH THE EVENING. SOME LATE AFTERNOON BREEZINESS CAN BE EXPECTED WITH GUSTS AROUND 20-25KTS /POSSIBLY AROUND 30KTS AT BLH AND IPL/...OTHERWISE WINDS WILL BE LIGHT AND WILL FAVOR TYPICAL DIURNAL PATTERNS. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SUNDAY THROUGH THURSDAY... PRETTY QUIET WEATHER EXPECTED NEXT WEEK. SOME LOCALIZED BREEZINESS IS POSSIBLE MONDAY AND TUESDAY AFTERNOONS AS A TROUGH MOVES THROUGH UTAH AND ARIZONA...BUT WINDS SHOULD REMAIN AT OR BELOW 20MPH. WINDS ARE LIKELY TO REMAIN ON THE LIGHT SIDE THEREAFTER AS HIGH PRESSURE SETTLES OVERHEAD. HUMIDITIES WILL REMAIN LOW THROUGH THE PERIOD...WITH MINIMUM RELATIVE HUMIDITIES DROPPING INTO THE SINGLE DIGITS EACH DAY WITH FAIR OVERNIGHT RECOVERY EXPECTED. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...LEINS/VASQUEZ AVIATION...KUHLMAN FIRE WEATHER...LEINS/KUHLMAN
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
407 AM MDT FRI MAY 17 2013 .SHORT TERM...DRIER AIR IN INCREASING SOUTHWEST FLOW ALOFT WILL SPREAD ACROSS THE AREA TODAY. AT THE SFC LOW PRESSURE WILL EXTEND FM SERN WY INTO ERN CO WITH INCREASING SLY WINDS BY AFTN OVER THE NERN PLAINS. LATE AFTN CAPES WILL RANGE FM 1500-2000 J/KG OVER THE FAR NERN CORNER EAST OF A STERLING TO LIMON LINE. SOUNDINGS SHOW CAP ERODING AFTER 22Z SO COULD SEE SOME ISOLD STORMS THRU 03Z. WITH FAVORABLE SHEAR PROFILE IF A FEW STORMS DO DVLP THEY COULD BECOME SVR. OTHERWISE IT WILL BE DRY OVER THE REST OF THE AREA WITH AFTN HIGHS WELL ABV NORMAL. CURRENT 850-700 MB TEMPS WOULD SUPPORT HIGHS IN THE UPPER 80S TO LOWER 90S ACROSS MOST OF NERN CO. RECORD HIGH AT DENVER IS 91 SO IT COULD GET CLOSE THIS AFTN. .LONG TERM...NO CHANGES TO THE FORECAST THINKING THROUGH THE WEEKEND AND INTO NEXT WEEK. MODELS CONTINUE TO SHOW A SLOWLY EVOLVING UPPER AIR PATTERN THAT FEATURES A BROAD UPPER TROUGH SETTLING OVER THE STATE SATURDAY AFTERNOON AND THEN TAKING TIL TUESDAY TO MOVE ON TO THE NORTHERN PLAINS. WHILE THE UPPER TROUGH LAGS OVER THE STATE...COOLER AND SOMEWHAT UNSETTLED WEATHER WILL PREVAIL WITH PERIODS OF SHOWERS AND POSSIBLY SOME EMBEDDED THUNDERSTORMS ACROSS THE FORECAST AREA. DYNAMIC FORCING WITH THE UPPER TROUGH WILL NOT BE ALL THAT STRONG...SO PRECIPITATION AMOUNTS LOOK LIKE THEY WILL ONLY BE LIGHT TO MODERATE. THE COOLEST DAY OF THE SET APPEARS TO BE MONDAY...WITH A GRADUAL WARMING TREND EXPECTED THROUGH THE REMAINDER OF NEXT WEEK. THE COOLER THAN NORMAL TEMPERATURES ALONG WITH PERIODS OF LIGHT RAIN SHOULD HELP THE SPRING VEGETATION STAY GREEN FOR A LITTLE LONGER. && .AVIATION...VFR THRU TONIGHT. SLY WIND EARLY THIS MORNING MAY BECOME MORE SWLY BY 14Z. BY 18Z THE RAP HAS THE WINDS STAYING SSW WHILE THE NAM IS MORE WLY. BY 21Z BOTH MODELS SHOW THE WNDS SSW. FOR NOW WILL KEEP THEM SSW THRU THE AFTN. FOR TONIGHT WILL KEEP THE WINDS DRAINAGE OVERNIGHT. && .HYDROLOGY...NO ISSUES. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...RPK LONG TERM....DANKERS AVIATION...RPK
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
701 AM CDT FRI MAY 17 2013 .UPDATE... ISSUED AT 649 AM CDT FRI MAY 17 2013 THE NOCTURNAL MCS WILL CONTINUE MOVING EAST FROM MN INTO WI THIS MORNING BEFORE SLOWLY DISSIPATING. BOUNDARIES LEFT OVER FROM THAT CONVECTION WILL BE THE PRIMARY FOCUS FOR DIURNAL CONVECTION TODAY. MCS AND LIFT TOOLS PER RAP TRENDS SHOW THE THETA E GRADIENT AND ASSOCIATED CONVERGENCE/LIFT IS JUST NORTH OF THE AREA. THUS DRY CONDITIONS ARE EXPECTED THROUGH MID DAY ACROSS THE AREA. THE CURRENT FCST HAS CONVECTION DEVELOPING IN THE AFTERNOON BUT IT IS DEPENDENT ON WHEN CONVECTIVE TEMPERATURE IS ACHIEVED. IF THE RAP IS CORRECT WE WOULD REMAIN BELOW CONVECTIVE TEMPERATURE. HOWEVER... THE RAP TRENDS DO SHOW AREAS OF CONVERGENCE DEVELOPING DURING THE AFTERNOON ALONG WITH WEAK THETA E GRADIENTS. SO...ISOLATED TO SCATTERED CONVECTION IS EXPECTED THIS AFTERNOON WITH THE NORTH THIRD MORE FAVORED DUE TO THE PROXIMITY OF THE FRONTAL BOUNDARY. STORMS WILL BE SLOW MOVING DUE TO THE UPPER RIDGE SO ANY THUNDERSTORM THAT DEVELOPS WILL HAVE THE POTENTIAL TO PRODUCE VERY LOCALIZED HEAVY RAINFALL OF AN INCH OR MORE. ..08.. && .SYNOPSIS... ISSUED AT 229 AM CDT FRI MAY 17 2013 06Z SFC ANALYSIS HAS A WEAK LOW IN WESTERN IOWA JUST EAST OF KSUX AND ANOTHER IN SOUTHERN SOUTH DAKOTA. AN EAST/WEST FRONTAL BOUNDARY RAN FROM NORTHERN OHIO...THROUGH CENTRAL INDIANA...AND TO THE LOW NEAR KSUX. FLOW OFF LAKE MICHIGAN HAD DEW POINTS RANGING FROM THE UPPER 30S NORTH OF THE FRONT TO 50S AND LOW 60S SOUTH OF THE FRONT. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 229 AM CDT FRI MAY 17 2013 THE CURRENT CONVECTION ON RADAR IS OCCURRING ALONG A THETA E GRADIENT AND MOISTURE/TEMPERATURE GRADIENTS FROM THE 850MB FRONT. MOST OF THE AREA WILL REMAIN DRY THROUGH SUNRISE EXCEPT FOR VERY ISOLATED CONVECTION IN THE HWY 20 CORRIDOR. THE MORNING HOURS ARE EXPECTED TO BE MAINLY DRY WITH PASSING CLOUDS AS THE THETA E GRADIENT MOVES NORTH INTO WISCONSIN. DIFFERENTIAL HEATING COMBINED WITH AN APPROACHING VORT MAX SHOULD RESULT IN ISOLATED TO SCATTERED CONVECTION DEVELOPING BY LATE MORNING IN THE EASTERN CWFA. DURING THE AFTERNOON HOURS...ISOLATED TO SCATTERED CONVECTION WILL EXPAND TO MOST OF THE CWFA AS CONVECTIVE TEMPERATURES ARE REACHED. THE PROXIMITY OF THE UPPER RIDGE MEANS THAT STEERING CURRENTS FOR THE CONVECTION ARE VERY WEAK. THUS THOSE AREAS THAT DO SEE RAIN THIS AFTERNOON WILL HAVE THE POTENTIAL TO SEE LOCALLY HEAVY RAINFALL. CONVECTION WILL SLOWLY DIMINISH WITH SUNSET BUT ISOLATED TO SCATTERED CONVECTION IS EXPECTED TO CONTINUE INTO THE EVENING OVER ROUGHLY THE NORTHEAST HALF OF THE CWFA. BY LATE EVENING MAINLY DRY CONDITIONS ARE EXPECTED WITH LITTLE IF ANY CONVECTION AFTER MIDNIGHT. 08 .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 229 AM CDT FRI MAY 17 2013 MAIN CHALLENGE IS THE PROBABLE SEVERE WEATHER RISKS SUN/MON. OVERVIEW...INITIALIZATION AND VERIFICATION FAIR WITH ALL SOLUTIONS HAVING DIFFICULTY WITH ONGOING CENTRAL IOWA MCS EVENT. COUPLED WITH BL DEWPOINT ISSUES SUGGEST AGAIN USE OF CONCEPTUAL PRECIPITATION EVOLUTION TOOLS DERIVED FROM THE FORCING OF A BLEND OF GEM-NH /HI-RES ECMWF/GFS. THIS SUPPORTS A DECENT RISK OF SEVERE STORMS SUN/MON WITH PHASING AND CONVECTIVE ISSUES THAT SHOULD BETTER CLARIFIED IN THE NEXT 24 HOURS. HIGHER END SEVERE STORM EVENTS FOR REGION APPEAR MARGINAL ATTM FOR THE AREA WITH LOW/MODERATE SEVERE EVENTS SUGGESTED ATTM. SATURDAY...MINOR CHANGES WITH AREA LIKELY PARTLY SUNNY AND DRY AHEAD OF SEASONABLY STRONG UPPER LEVEL SYSTEM MOVING INTO WEST CENTRAL PLAINS. WARM AND A BIT HUMID WITH HIGHS IN THE LOWER 80S AND LOWS MOSTLY IN THE LOWER 60S WITH DEWPOINTS 60-64F. SOME PATCHY FOG POSSIBLE WITH ANY CLEARING FOR LATER SHIFTS TO CONSIDER. SUNDAY AND MONDAY. GOOD SHEAR AND AT LEAST MODERATE INSTABILITY SUPPORT ONE OR MORE CONVECTIVE EVENTS SUGGESTED WITH ENVIRONMENT MOSTLY FAVORABLE FOR CONVECTIVE BOWING SEGMENTS ATTM. SEVERE WEATHER AREAL TOOL AND BLEP/HELP ALGORITHMS SUGGEST WITH T/TDS AOA 83/63 OF 60-70 MPH STRAIGHT LINE WINDS AND SOME HAIL THAT COULD APPROACH 1.75 INCHES WITH WBZ OF ~11K AGL AND SBCAPE OF 2000-3000 J/KG. IF ANY WAVE FORMS IN LATE PM/EVENING THERE IS A RISK OF ISOLATED TORNADOES BUT THIS APPEARS MARGINAL DUE TO CURRENT JET STRUCTURE AND TIMING. HIGHS SUGGESTED BASED ON PARTLY SUNNY SKIES SHOULD BE IN THE LOWER/MIDDLE 80S AND MINS MOSTLY IN THE MIDDLE 60S. PW/S OF 1.25+ INCHES DO SUPPORT LOCALLY HEAVY RAINFALL WITH ANY TRAINING OF STORMS. POPS IN THE LIKELY CATEGORY TO THE MID/HIGH CHANCE WITH TIMING MAIN ISSUE. LOCAL FORCING AND HEAVY RAIN TECHNIQUES DO SUPPORT MOST AREAS TO PICK UP AN INCH OR MORE OF RAIN WITH PASSAGE OF UPPER LEVEL SYSTEM OVER NEXT 96+ HOURS. TUESDAY...A CHALLENGE WITH WAVE BASED ON CONVECTION FIRING OVER SOUTHERN PLAINS THE KEY ISSUE. JET STRUCTURE SUPPORTS DECENT RAIN EVENT WITH LOTS OF CLOUDS AND THIS WOULD IMPACT HIGH TEMPERATURES FOR LATER SHIFTS THAT MAY NEED LOWERING OVER CENTRAL AND SE SECTIONS. POPS MAY NEED RAISING AS WELL BY 10-20 PERCENT WITH MODERATE TO LOW END HEAVY AMOUNTS SUGGESTED. CONVECTIVE FEEDBACK QUESTION SHOULD BE CLARIFIED MORE IN THE NEXT 24-36 HOURS. TUESDAY NIGHT...UPPER LOW MOVES INTO AREA WITH CHANCE OF LOW TOP CONVECTION OF SHOWERS AND BRIEF THUNDERSTORMS. MINS OF 55-60F WITH TEMPS POSSIBLY A BIT TOO COOL IN FAR SE SECTIONS WITH CLOUDS. WEDNESDAY AND THURSDAY...UPPER LOW TO SLIDE SLOWLY EAST WITH CHANCE SHOWERS AND POSSIBLY ISOLATED THUNDER WITH PARTLY TO MOSTLY CLOUDY SKIES. HIGH TEMPERATURES 67-77F SUGGESTED. LOWS IN THE 50S WED AM AND MID/UPPER 40S TO LOWER 50S SE SECTIONS THU AM. SEASONABLY STRONG CANADIAN HIGH PRESSURE TO THEN DOMINATE AND KEEP AREA COOL WITH LOW DEWPOINTS AND BELOW NORMAL INTO NEXT WEEKEND. NICHOLS && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 649 AM CDT FRI MAY 17 2013 VFR WX WILL BE SEEN THROUGH 12Z/18. NEW CONVECTION WILL DVLP AFT 18Z/17 BUT THE PROBABILITY OF A SHRA OR TSRA AFFECTING A TAF SITE IS 15 PERCENT. VCTS OR VCSH WAS INCLUDED IN THE 12Z TAFS TO REFLECT THE POTENTIAL FOR NEARBY CONVECTION FROM 20Z/17 TO 03Z/18. IF A SHRA/TSRA AFFECTS A TAF SITE CIGS SHOULD REMAIN VFR. VSBYS MAY DROP TO MVFR OR IFR FROM HEAVY RAIN. ..08.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ UPDATE...08 SYNOPSIS...08 SHORT TERM...08 LONG TERM...NICHOLS AVIATION...08
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1124 AM EDT FRI MAY 17 2013 LATEST UPDATE... UPDATE/MARINE .SYNOPSIS... ISSUED AT 334 AM EDT FRI MAY 17 2013 MORE CLOUDS WILL MOVE INTO THE AREA TODAY AS A SYSTEM TO OUR WEST TRIES TO MOVE IN. DRY LOW LEVELS WILL KEEP RAIN CHANCES NEAR ZERO FOR THE AREA. SOME LOW CHANCES OF RAIN WILL BE POSSIBLE TONIGHT AND EARLY SATURDAY AS A FRONTAL SYSTEM MOVES BY JUST NORTHWEST OF THE AREA. CONDITIONS SHOULD CLEAR OUT A BIT FOR LATER SATURDAY AND SUNDAY WITH WARM TEMPERATURES EXPECTED. BETTER CHANCES FOR RAINFALL WILL COME TOWARD MONDAY AND LINGER THROUGH WEDNESDAY NEXT WEEK. && .UPDATE... ISSUED AT 1121 AM EDT FRI MAY 17 2013 PRECIPITATION MOVING OFF THE WI SHORELINE HAS BEEN SLOW TO DIMINISH. GFS 06Z RUN SEEMED TO HAVE A BETTER HANDLE ON THE PRECIPITATION THAN THE NEW NAM. HRRR 12Z RUN AND OLD GFS PAINT PRECIPITATION ACROSS MUCH OF NRN ZONES...NORTH OF MKG TO GRR WITH PRECIPITAITON THIS AFTERNOON. WILL BUMP UP POPS AND LOWER TEMPERATURES FOR THIS REGION. UPDATE ISSUED AT 949 AM EDT FRI MAY 17 2013 ADDED A FEW RAIN SHOWERS TO THE FORECAST FOR LUDINGTON TO NEAR CADILLAC. RADAR TRENDS SHOW INCREASING RETURNS AND THE OBSERVATION OUT OF CADILLAC INDICATED THAT THE PRECIPITATION WAS REACHING THE GROUND. AM MONITORING THE WEAKENING THUNDERSTORMS OVER IN ERN WISCONSIN. MAY NEED TO ADD SOME PRECIPITATION TO THE MUSKEGON FORECAST AS WELL IF THEY DO NOT WEAKEN QUICKLY ENOUGH. I DID ADJUST TEMPERATURES DOWNWARD SLIGHTLY FOR NORTHERN ZONES DUE TO THE CLOUDS AND PRECIPITATION. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 334 AM EDT FRI MAY 17 2013 THE MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING PCPN CHCS THROUGH THE PERIOD. MOST OF THE PERIOD THROUGH THE WEEKEND LOOKS DRY...HOWEVER THERE ARE A COUPLE OF PERIODS WHERE RAIN POTENTIAL HAS TO BE ADDRESSED. WE EXPECT THAT THE AREA WILL STAY DRY DURING THE DAY TODAY. HIGH CLOUDS STREAMING IN FROM THE WEST ARE SHROUDING THE AREA PRETTY WELL THIS MORNING. SOME MID CLOUD COVER IS SHOWING UP OVER WEST CENTRAL AREAS OF THE CWFA. THERE IS SOME MOISTURE TRANSPORT/THETA E ADVECTION TAKING PLACE IN THE MID LEVELS. THE BEST PUSH OF EACH IS OCCURRING FURTHER WEST IN WI. IN ADDITION...THE EASTERLY FLOW IS CONTINUING TO FEED DRIER AIR IN ACROSS THE AREA. THESE FACTORS SHOULD KEEP THE ENTIRE AREA DRY TODAY. TEMPS WILL LIKELY BE A COUPLE OF DEGREES COOLER TODAY WITH LESS SOLAR INSOLATION. THE FIRST CHC OF RAIN THAT COULD OCCUR WOULD BE DURING THE PERIOD FROM TONIGHT INTO SAT MORNING ACROSS THE N/NW COUNTIES. WE HAVE ADDED A SLIGHT CHC OF SHOWERS TO THE N/NW COUNTIES. THE BEST MID LEVEL THETA E ADVECTION/MOISTURE TRANSPORT CONTINUES TO BE W/NW OF THE AREA. THERE ARE SOME SOLUTIONS SHOWING THERE COULD BE JUST ENOUGH FORCING AND DEEP ENOUGH MOISTURE TO GENERATE ENOUGH PCPN TO REACH THE GROUND THROUGH THE DRIER LOWER LEVELS. BY SAT AFTERNOON...WE SEE SUFFICIENT DIGGING OF THE WRN TROUGH AND RESULTANT BUILDING OF THE UPPER RIDGE OVER THE AREA TO PUSH THE CLOUDS AND PCPN WELL NORTH OF THE CWFA. MORE SUNSHINE COMPARED TO THIS AFTERNOON WILL HELP TO WORK ON THE WARMING H850 TEMPS TO AROUND 12-13C AND SUPPORT HIGHS AROUND 80. THE LOW LEVEL FLOW WILL BE VEERING A BIT TO THE S/SE AS THE HUDSON BAY RIDGE SHIFTS EAST. THIS WILL HELP TO START ADVECTING SOMEWHAT HIGHER DEW POINTS INTO THE AREA. FCST SOUNDINGS SHOW THAT THE LOW LEVELS WILL STILL BE JUST A LITTLE TOO DRY YET TO ALLOW FOR ANY POP UP DIURNAL CONVECTION ALONG ANY BOUNDARIES. WE WILL SEE MORE SUNSHINE ON SUN WITH TEMPS INCREASING A CATEGORY AS TEMPS ALOFT UNDER THE RIDGE INCREASE A COUPLE OF DEGREES C. SUN MIGHT SEE A SLIGHTLY BETTER CHC FOR A POP UP SHOWER DURING THE AFTERNOON HOURS AS BETTER LOW LEVEL MOISTURE DOES ADVECT IN. FCST SOUNDINGS INDICATE THAT THE MID AND UPPER LEVELS MAY BE JUST A TAD TOO WARM YET WITH THE UPPER RIDGE OVERHEAD TO ALLOW SHOWERS TO FORM. THE CHC IS NOT ZERO...HOWEVER IT LOOKS JUST A LITTLE TOO LOW AT THIS TIME TO JUSTIFY ADDING IN THE CHC. .LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY) ISSUED AT 334 AM EDT FRI MAY 17 2013 LONG TERM PATTERN BEGINS WITH THE UPPER RIDGE OVERHEAD AND AN UPPER LOW ACROSS THE NORTHERN PLAINS. THE RIDGE GRADUALLY SHIFTS SOUTH AND EAST ALLOWING THE GREAT LAKES TO BECOME MORE UNDER THE INFLUENCE OF THE UPPER LOW NEXT WEEK. THE UPPER LOW FILLS WITH TIME AND BECOMES ABSORBED INTO A EASTERN CANADIAN UPPER TROUGH. BOTH THE GFS AND ECMWF PAINT THIS SCENARIO. AT THE SURFACE LOW PRESSURE WILL GRADUALLY MOVE INTO THE GREAT LAKES STATES FROM THE WEST INTO MID WEEK. ISOLATED SHOWERS AND STORMS APPEAR POSSIBLE SUNDAY NIGHT...WITH CHANCES RAMPING UP TO LIKELY FROM TUESDAY INTO WEDNESDAY AS THE LOW AND A SURFACE WARM FRONT WILL BE IN THE AREA. THE THUNDER THREAT DIMINISHES INTO WEDNESDAY NIGHT AND THURSDAY AND HAVE SHOWERS ONLY IN THE FORECAST DURING THESE PERIODS. THE LONG TERM PERIOD LOOKS TO BE WET OVERALL...WITH RAINFALL IN EXCESS OF AN INCH POSSIBLE AS THE UPPER LOW SLOWLY MOVES THROUGH THE REGION. TEMPERATURES WILL START OUT WARM IN SOUTHERLY FLOW...TRENDING BACK TOWARD NORMAL INTO MID WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 749 AM EDT FRI MAY 17 2013 VFR CONDITIONS ARE EXPECTED THE NEXT 24 HOURS...AS MID AND HIGH CLOUDS DOMINATE THE DAYTIME HOURS. BASES SHOULD BE AT OR ABOVE 9000FT. CEILINGS MAY LOWER SOME TONIGHT...BUT 5000-6000FT BASES WILL KEEP CONDITIONS AT VFR. WINDS WILL BE STEADY FROM THE EAST AT 8-12 KNOTS TODAY AND TONIGHT. && .MARINE... ISSUED AT 1121 AM EDT FRI MAY 17 2013 EXPANDED THE MENTION OF RAIN IN THE FORECAST FOR NORTHERN MARINE ZONES. && .FIRE WEATHER... ISSUED AT 334 AM EDT FRI MAY 17 2013 CONDITIONS LOOK TO BE A SLIGHT BIT BETTER THAN THU WITH REGARD TO FIRE DANGER...ALTHOUGH THE FIRE DANGER WILL REMAIN ELEVATED. MORE CLOUD COVER WILL LIMIT THE AMOUNT OF HEATING AND THE MIXING DOWN OF DRIER AIR. CONDITIONS WILL ONCE AGAIN APPROACH RED FLAG CRITERIA... HOWEVER WE EXPECT RH/S TO REMAIN JUST SHY OF THE RED FLAG CRITERIA....WINDS TO REMAIN JUST UNDER CRITERIA WITH A FEW GUSTS TO NEAR CRITERIA...AND TEMPS RIGHT AROUND THE THRESHOLD OF 75 DEGREES. WE WILL NEED TO MONITOR THE SITUATION THIS AFTERNOON. DEW POINTS SHOULD COME UP SOME OVER THE WEEKEND AS THE FLOW BECOMES A LITTLE MORE SOUTHERLY AND MOISTURE WILL ADVECT INTO THE AREA. THIS SHOULD KEEP RED FLAG CRITERIA FROM BEING REACHED. && .HYDROLOGY... ISSUED AT 334 AM EDT FRI MAY 17 2013 WE WILL NOT SEE ANY HYDROLOGY ISSUES THROUGH THE WEEKEND WITH LIKELY NO RAIN AT ALL. THE CHANCES OF ANY HYDROLOGY ISSUES MON-WED NEXT WEEK WITH RAINFALL WITH THE SYSTEM DO NOT LOOK THAT GREAT EITHER. THE SURFACE OF THE SOIL AROUND THE AREA HAS DRIED CONSIDERABLY...AND RIVER/STREAM LEVELS HAVE RETURNED TO NEAR AVERAGE FLOWS. THE MODELS ARE SHOWING RAINFALL AMOUNTS OF OVER AN INCH POSSIBLE FROM MON-WED. THIS SHOULD NOT ALL COME AT ONCE...AND THE GROUND SHOULD SOAK IT UP PRETTY WELL. RIVER LEVELS WILL COME UP...HOWEVER WE DO NOT EXPECT ANY NOTABLE ISSUES AT THIS TIME. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ UPDATE...MJS SYNOPSIS...NJJ SHORT TERM...NJJ LONG TERM...DUKE AVIATION...DUKE FIRE WEATHER...NJJ HYDROLOGY...NJJ MARINE...MJS
AREA FORECAST DISCUSSION
NWS GAYLORD MI
937 AM EDT FRI MAY 17 2013 .SYNOPSIS... ISSUED AT 352 AM EDT FRI MAY 17 2013 HIGH PRESSURE WILL REMAIN IN CONTROL OF NORTHERN MICHIGANS WEATHER THROUGH TODAY...RESULTING IN DRY WEATHER UNDER PARTLY SUNNY SKIES AND SEASONABLE TEMPERATURES. WARM AND MOIST AIR PRESSING INTO THE MIDWEST AND GREAT LAKES WILL BRING A CHANCE FOR SHOWERS TO THE NORTH WOODS OVER THE WEEKEND...MAINLY ON SATURDAY. && .UPDATE... ISSUED AT 936 AM EDT FRI MAY 17 2013 INCREASINGLY CHALLENGING FORECAST DEVELOPING FOR TODAY. UPSTREAM REMNANT MCS ON LEADING EDGE OF THETA-E ADVECTION/NOSE OF LOW LEVEL JET CONTINUES TO DRIVE EAST ACROSS SOUTHERN WISCONSIN...WITH SOME LEADING EDGE RETURNS SPILLING INTO SOUTHWEST SECTIONS OF OUR AREA (EVEN SOME EVIDENCE OF MID LEVEL FGEN HELPING MAINTAIN/EXPAND THESE LEADING EDGE SHOWERS). LOW LEVELS REMAIN DRY...AND JUST HAD FIRST REPORTS OF RAIN REACHING THE SURFACE AT CADILLAC. HAVE ADJUSTED FORECAST A TOUCH MORE PESSIMISTICALLY SOUTH OF TRAVERSE CITY...ALTHOUGH TRENDS SUGGEST PERHAPS NOT PESSIMISTICALLY ENOUGH. LATEST HIGH RES HRRR SOMEWHAT DISCONCERTING...DRIVING DECAYING MCS ACROSS THE SOUTH HALF OF THE AREA THIS AFTERNOON...PRODUCING RATHER WIDESPREAD LIGHT SHOWERS. PERUSAL OF OTHER GUIDANCE AND MODEL DERIVED SOUNDINGS SUGGEST OTHERWISE...WITH DEEP LOW LEVEL DRY LAYER AND LOSS OF DYNAMICS ESSENTIALLY FULLY DECAYING THIS ACTIVITY BEFORE IT REACHES OUR AREA. THAT SAID...RADAR RETURNS MORE THAN OMINOUS...AND DEFINITE FUTURE CHANGES MORE THAN EXPECTED. MORE CLOUDS/RAIN WOULD ALSO MEAN SIGNIFICANTLY COOLER TEMPERATURES ACROSS THE SOUTH. WILL CONTINUE TO MONITOR. UPDATE ISSUED AT 606 AM EDT FRI MAY 17 2013 FORECAST APPEARS ON TRACK FOR THE MOMENT. SUBSTANTIAL HIGH CLOUDS FROM UPSTREAM CONVECTION HAVE OVERSPREAD MUCH OF THE CWA... ESPECIALLY NRN LOWER MICHIGAN. SATELLITE TRENDS REVEAL ABUNDANT HIGHER CLOUD COVER UPSTREAM THAT WILL CONTINUE TO STREAM THROUGH THE REGION TODAY. THUS PARTLY SUNNY TO OCCASIONALLY MOSTLY CLOUDY SKIES SHOULD WORK OUT. OTHERWISE...QUITE A FEW LOCATIONS ARE IN THE UPPER 30S WITH A FEW SPOTS COLDER (PLN IS 32F). WARMEST LOCATIONS ARE IN THE SW COUNTIES (TVC/FKS/MBL...ETC). CAN PROBABLY SAFELY TRIM THOSE COUNTIES OUT OF THE FREEZE ADVISORY EARLY. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 352 AM EDT FRI MAY 17 2013 OVERVIEW: FAIRLY PROGRESSIVE FLOW PATTERN ACROSS THE CONUS CURRENTLY BUT STARTING TO BECOME MORE AMPLIFIED AS TROUGHINESS DEEPENS ALONG THE WEST COAST...AND DOWNSTREAM RIDGING BUILDS THROUGH THE PLAINS AND INTO THE GREAT LAKES. RIDGING GRADUALLY BUILDS INTO THE GREAT LAKES HEADING THROUGH THE WEEKEND SIGNALING WARMER DAYS AHEAD. MEANWHILE...HIGH PRESSURE HAS NUDGED IT/S WAY DOWN OUT OF ONTARIO AND INTO THE WESTERN GREAT LAKES. ONGOING MCS ACTIVITY TO OUR SOUTHWEST ACROSS IOWA...BUT WILL STAY WELL AWAY FROM US AS MOISTURE/INSTABILITY REMAINS DISPLACED WELL OFF TO OUR WEST AND SOUTH. TODAY...HIGH PRESSURE AND ANTECEDENT DRY AIRMASS WILL CONTINUE TO DOMINATE THE REGION WITH NO PRECIP ANTICIPATED. HOWEVER...THERE IS QUITE A BIT OF MID AND HIGH CLOUD COVER UPSTREAM FROM ONGOING CONVECTION AS WELL AS INCREASING WARM ADVECTION ACROSS THE PLAINS. THUS...WILL SEE VARIOUS ROUNDS OF MID AND HIGH CLOUD SLIDING THROUGH THE REGION...LEADING TO PARTLY CLOUDY TO OCCASIONALLY MOSTLY CLOUDY SKIES. TEMPERATURES...A LITTLE WARMER AS COMPARED TO THURSDAY WITH HIGHS RANGING FROM THE MID 60S TO LOWER 70S. FIRE WEATHER CONCERNS...DRY ANTECEDENT CONDITIONS PERSIST AND EXPECT INLAND SFC DEWPOINTS WILL DIP INTO THE LOWER 30S DURING THE AFTERNOON LIKE THURSDAY WITH MINIMUM RH VALUES GOING BELOW 25 PERCENT. HOWEVER...TEMPS WILL LARGELY REMAIN BELOW 75 FOR MOST AREAS AND WINDS WILL BE FAIRLY LIGHT (UNDER 10 MPH). YES IT WILL BE DRY BUT WITHOUT DECENT WIND...WILL NOT HAVE ELEVATED FIRE DANGER MENTIONED IN THE HWO FOR TODAY. TONIGHT...WARM AND MOIST AIR (HIGH THETA-E) BUILDS THROUGH THE PLAINS AND THE UPPER MIDWEST THROUGH THE COURSE OF THE NIGHT WITH THE STRONGEST SURGE/FORCING OCCURRING ACROSS THE NRN PLAINS AND UPPER MIDWEST WHERE ONE OR MORE CONVECTIVE SYSTEMS WILL LIKELY BE ONGOING OR DEVELOP. HERE AT HOME...NOT SO IMPRESSED. NW-SE ORIENTED THETA-E GRADIENT WILL BE INCHING UP THROUGH STATE THROUGH THE COURSE OF THE NIGHT. BUT AGAIN...MUCH STRONGER LOW LEVEL FLOW AND RESULTING FORCING (MOIST CONVERGENCE) WILL REMAIN WELL WEST-NORTHWEST OF THE CWA WHERE MOST CONVECTIVE ACTIVITY WILL BE CONFINED. SUPPOSE ITS PLAUSIBLE WE GET A FEW ELEVATED SHOWERS TO DEVELOP ALONG THE ADVANCING THETA-E GRADIENT ALTHOUGH LAPSE RATES ALOFT ARE JUST NOT THAT SUPPORTIVE OF CONVECTION. IN THE END...FOR CONTINUITY AND COLLABORATION WITH SURROUNDING OFFICES...DECIDED TO MAINTAIN CHANCE POPS FOR SHOWERS OVER NW LOWER MICHIGAN OVERNIGHT BUT HAVE TRIMMED POPS BACK TO 30 PERCENT OR LESS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 352 AM EDT FRI MAY 17 2013 A WARMER AND PROGRESSIVELY MORE MOIST SOUTHEASTERLY FLOW WILL LEAD TO CHANCES FOR SHOWERS THIS WEEKEND. THERE WILL BE CHANCES FOR SHOWERS AND EVEN THUNDERSTORMS EARLY NEXT WEEK WHICH WILL BECOME LIKELY BY THE MIDDLE OF NEXT WEEK...AS A CUTOFF UPPER TROUGH APPROACHES FROM OUR SOUTHWEST. FINALLY...CONDITIONS MOST LIKELY DRY OUT BY THURSDAY AS THIS SYSTEM RETREATS TO THE SOUTHEAST. THE MAIN LONG TERM FORECAST CONCERNS REVOLVE AROUND POPS AND HOW MUCH IT WILL WARM UP THIS WEEKEND INTO EARLY NEXT WEEK. SATURDAY AND SUNDAY...MODELS ARE ONLY IN FAIR AGREEMENT ON THE TIMING AND AMOUNT OF MOISTURE ADVECTION INTO THE REGION AS THETA-E RIDGING APPROACHES THE FORECAST AREA BUT WEAKENS AS IT DOES SO. THIS IS IN RESPONSE TO A DECAYING AREA OF LOW PRESSURE MOVING BY TO THE NORTHWEST. IT IS STILL UNCERTAIN IF IT WILL MOISTEN UP ENOUGH ACROSS NORTHERN MICHIGAN TO ACTUALLY RAIN...AS THE MAIN ACTION LOOKS TO REMAIN TO OUR WEST. SO WILL BACK OFF ON POPS TO SLIGHT AND LOW CHANCES FOR SHOWERS. HIGHS SATURDAY RANGING FROM THE MIDDLE 60S TO MIDDLE 70S...WITH THE WARMER 70S TO LOWER 80S ON SUNDAY EXPECTED. LOWS SATURDAY NIGHT IN THE MIDDLE 40S TO LOWER 50S. MONDAY THROUGH THURSDAY...SHOWERS AND THUNDERSTORM CHANCES INCREASE MONDAY THEN BECOME LIKELY MONDAY NIGHT INTO WEDNESDAY AS A CUTOFF UPPER LEVEL TROUGH AND WARM FRONT APPROACH FROM THE SOUTHWEST. EXTENDED MODELS THEN VARY ON THE TIMING OF DRYING FROM THE NORTH...BUT WILL PENCIL THURSDAY IN AS A DRY DAY AS THIS SYSTEM IS SHOWN TO SLOWLY RETREAT TO OUR SOUTHEAST. REMAINING WARM WITH HIGHS IN THE 70S TO LOWER 80S MONDAY...FOLLOWED BY A SLOW COOLING TREND WITH TEMPERATURES ENDING UP IN THE UPPER 50S TO LOWER 60S FOR HIGHS BY THURSDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 606 AM EDT FRI MAY 17 2013 SOLID VFR CONDITIONS THROUGH THE UPCOMING TAF FORECAST PERIOD... BUT WITH GRADUALLY LOWERING CIGS THIS AFTERNOON AND TONIGHT. LIGHT WINDS (UNDER 10 KNOTS) WITH WIND DIRECTIONS LAKE DOMINATED AT THE TAF SITES. && .MARINE... ISSUED AT 352 AM EDT FRI MAY 17 2013 LIGHT WINDS/LOW WAVES WILL PREVAIL ON THE LAKES TODAY AND TONIGHT WITH NO MARINE HEADLINES NEEDED. SOUTH-SOUTHEAST FLOW INCREASES SATURDAY AND SATURDAY NIGHT AND A HANDFUL OF SMALL CRAFT ADVISORIES MAY BE NEEDED. AT THAT TIME. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...MB SYNOPSIS...AS SHORT TERM...BA LONG TERM...AS AVIATION...BA MARINE...BA
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
641 AM CDT FRI MAY 17 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 313 AM CDT FRI MAY 17 2013 THE MAIN FEATURE OF INTEREST TODAY IS THE UPPER LOW WHICH PROFILER AND WATER VAPOR SUGGEST IS CURRENTLY LOCATED ACROSS EXTREME SRN MO NEAR WEST PLAINS. THE MODELS ARE IN RELATIVELY GOOD AGREEMENT TRACKING THE LOW E/NEWD TODAY WITH THE MORE SRN POSITION OF THE LOCAL WRF AND RUC PREFERRED. THIS TRACK WOULD TAKE THE LOW ACROSS THE EASTERN OZARKS THIS MORNING AND INTO SRN IL THIS AFTENOON. THE BIGGEST UNCERTAINTY WITH THIS SYSTEM IS THE N/NW EXTENT OF PRECIPITATION AND COVERAGE. CLOUD TOPS HAVE BEEN COOLING THE LAST FEW HOURS IS ASSOCIATION WITH AN INCREASING AMOUNT OF SHOWERS. THE EXPLICIT GUIDANCE GENERALLY DEPICTS SCATTERED COVERAGE DIMINISHING WITH NORTHWARD EXTENT. THIS SEEMS REASONABLE AND HAS BEEN GENERALLY ACCEPTED WITH THE HIGHEST POPS ACROSS SE MO INTO SRN IL. THE THREAT OF CONVECTION SHOULD INCREASE LATER THIS MORNING IS ASSOCIATION WITH HEATING AND DESTABILIZATION. THE UPPER LOW SHOULD BE IN SRN IL BY EARLY EVENING...DEPARTING TO THE EAST NORTHEAST. ANY PRECIPITATION IN THE WAKE OF THE LOW SHOULD BE STRONGLY TIED TO HEATING...DISSIPATING DURING THE EVENING. GLASS .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 313 AM CDT FRI MAY 17 2013 SATURDAY LOOKS LARGELY DRY AS A RIDGE ALOFT BUILDS INTO THE AREA IN ASSOCIATION WITH OVERALL UPSTREAM AMPLIFICATION. LOW LEVEL WAA WILL INCREASE AND THIS COMBINED WITH LESS CLOUD COVER WILL RESULT IN WARMER TEMPERATURES. THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL RE-ENTER THE PICTURE ON SAT NIGHT IN RESPONSE TO LOW LEVEL WAA/MCON VIA A SWLY LLJ...BRINGING THE POTENTIAL FOR ELEVATED ACTIVITY TO THE NORTH OF A SLOWLY LIFTING WARM FRONT. THE HIGHEST PROBABILIT AT THIS TIME APPEARS TO BE ACROSS NRN MO INT CENTRAL IL. THERE COULD BE ONGOING/RESIDUAL ELEVATED ACTIVITY NORTH OF THE WARM FRONT ACROSS NE MO/WEST CENTRAL IL ON SUNDAY MORNING. OTHERWISE INCREASING SOUTHERLY FLOW AND WAA SHOULD RESULT IN CONTINUED WARMER TEMPERATURES WITH SOME LOCATIONS PUSHING 90 DEGREES. A VERY ACTIVE PERIOD WILL BEGIN TO UNFOLD LATE SUNDAY AFTERNOON AND CONTINUE THROUGH AT LEAST TUESDAY NIGHT AS RATHER DEEP AND BROAD UPPER TROF/UPPER LOW MOVES SLOWLY EAST AND A SERIES OF SHORT WAVES EJECT E/NEWD. A MOIST AND VERY UNSTABLE AIR MASS WILL BE IN PLACE AND THIS COMBINED WITH FAVORABLE DEEP LAYER SHEAR WILL SUPPORT MULTIPLE SEVERE WEATHER EPISODES OVER A 3 DAY PERIOD MIGRATING WEST TO EAST ACROSS THE CWA WITH THE MOST ACTIVE PERIOD FROM MONDAY THROUGH TUESDAY NIGHT. GLASS && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 621 AM CDT FRI MAY 17 2013 FEW CHANGES WERE MADE TO PREV FORECAST WHICH APPEARS TO BE ON TRACK. EXPECT CHANCE OF PRECIP TO INCREASE LATE THIS MORNING AND INTO MID AFTERNOON...MAINLY FOR SUS/CPS. WINDS WILL BE SELY AND AOB 6 KTS. EXPECT FG/ST TO DEVELOP TONIGHT WITH AMPLE MOISTURE AND WEAK FLOW. ATTM...EXPECT WORST CONDITIONS AT COU AND SUS/CPS. SPECIFICS FOR KSTL...EXPECT MVFR CLOUDS TO AFFECT TERMINAL LATER THIS MORNING AND INTO THE AFTERNOON. PRECIP CHANCES WILL INCREASE THRU THE MORNING WITH BEST CHANCES EARLY THIS AFTERNOON. WINDS ARE EXPECTED TO REMAIN SELY AOB 6 KTS. TILLY && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
632 AM CDT Fri May 17 2013 .SHORT TERM...(Today through Saturday night) Issued at 403 AM CDT FRI MAY 17 2013 Closed upper low over extreme north central AR will continue an eastward track and move away from the CWA today. Could see an isolated shower or storm over the far eastern counties later this morning and early afternoon as any remaining vorticity lobes rotate cyclonically westward. Stratus has formed over the southern CWA. These clouds on the northwest side of the upper low an increasingly moist boundary layer. 06z RAP has best handle on the current low cloud trends and followed. Airmass over the CWA is very similar to yesterday. However, except for the far northwest corner of MO believe max temperatures today may be a few degrees cooler than yesterday due to increased cloud cover. The earlier upstream convection over KS and NE was tied to a couple of weak vorticity lobes. Convection has all but dissipated and dont` expect it to reform today. Shortwave ridging aloft is progged to amplify as it moves east across the Central and Southern Plains this afternoon through Saturday. This should yield dry and warmer conditions on Saturday. Expect max temperatures in the middle to upper 80s. Saturday night is looking a tad more interesting as it no longer looks dry. NAM/GFS/ECMWF/GEM have been giving signals for the past couple of runs that elevated convection will form Saturday evening over eastern KS/western MO and quickly advance northeast Saturday night. With a stout elevated mixed layer providing an impediment to surface based convection, any activity will need to rely on isentropic ascent and a ramping up of the h8 low level jet.....and we have that. So, have no qualms in adding at least slight chance PoPs for Saturday night to most of the CWA. Even went with chance PoPs over the northeastern CWA as the initial activity will have had time to increase in coverage as it moves quickly northeast. .LONG TERM...(Sunday through Thursday) Issued at 403 AM CDT FRI MAY 17 2013 For Sunday, there remains a good chance for severe weather from the afternoon into the overnight hours. A trough is expected to move into the Plains by Sunday afternoon leading to a surface low that will move to our north. This will result in the entire area being in a broad warm sector with dewpoints likely in the mid to upper 60s. Model soundings show a strong CAP over the region but also with the potential for elevated showers/storms earlier in the day. This possible area of precipitation should move east into the Mississippi Valley by the afternoon leaving eastern Kansas and western Missouri to see better destabilization during the afternoon. CAPE values in the 2500 to 3500 J/kg range look likely given forecast dewpoints so we will see moderate to strong instability build across our western zones. The finer scale details of what impact the convection earlier in day will have will only be able to be resolved during the nowcast period. But strong instability and 0-6KM shear in the 40 to 50 kt range, oriented more normal to any initiating boundary, indicates supercells would be the most likely convective mode initially. Hodographs show a good amount of curvature by the afternoon and this is increased during the evening as the low level jet restrengthens overhead. Storms will likely initiate over eastern Kansas during the afternoon hours and become supercells. As winds veer into the evening and overnight hours storms should organize into more of a line/ convective complex. Large hail, damaging winds and a few tornadoes are possible with the initial storms before the convective mode changes and damaging winds becomes the primary concern. Monday will be greatly dependent upon what happens Sunday night, and as such confidence is quite a bit lower. Latest guidance suggest that the front will be nearly east of us by the evening hours with winds across the area veered southwesterly. Shear and instability are still supportive of severe weather, but the chances should be either across our eastern to southern zones or even east of the forecast area. We will really need to see how the weather pans out Sunday before a saying anything with any level of certainty. For the remainder of the extended forecast, the upper trough that affected the area Sunday and Monday should have cutoff over the Upper Midwest. Another segment of the upper trough will move through Wednesday and as a result there may be a few showers or storms across northern Missouri into central and eastern Missouri. A few showers and storm will remain a possibility into Thursday as northern portions of the forecast are still under the influence of the Upper Midwest upper low. The effects of the upper low will diminish by Friday as upper ridging spreads into the Plains. This will result in a warm up with drier conditions more likely for the weekend. The severe potential looks rather low for this stretch of time. && .AVIATION...(For the 12Z TAFS through 12Z Saturday Morning) Issued at 625 AM CDT FRI MAY 17 2013 Latest satellite imagery shows IFR/MVFR stratus is advecting rapidly north into west central MO/east central KS. Latest 09z RAP output has best handle on the low clouds and suggests low clouds will be around into late morning. A light southeast wind maintaining moisture within the boundary layer and minimal mixing until late this morning supports this forecast. Areas of MVFR fog will also accompany this cloudiness for the first few hours of the forecast. Should see clouds scatter out no later than noon with VFR conditions until the pre-dawn hours of Saturday morning when conditions favor MVFR fog developing. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ SHORT TERM...MJ LONG TERM...CDB AVIATION...MJ
AREA FORECAST DISCUSSION
NWS BILLINGS MT
923 AM MDT FRI MAY 17 2013 .UPDATE... FORECAST IS IN GOOD SHAPE TODAY AND ONLY MADE SOME MINOR CHANGES. PATCHY FOG STILL ON GOING FROM BAKER SOUTHWARD TO NEAR EKALAKA THIS MORNING. THE PATCHY FOG IS EXPECTED TO PERSIST THROUGH LATE MORNING. SEVERE WEATHER THREAT FOR LATE THIS AFTERNOON INTO EARLY EVENING STILL LOOKS GOOD FROM BROADUS TO EKALAKA. 12Z NAM SURFACE BASED CAPE NEAR 1000 J/KG IN THE ABOVE MENTION AREAS AND THE THREAT OF LARGE HAIL WILL BE POSSIBLE ALONG WITH HEAVY RAIN. FLASH FLOOD WATCH ALSO LOOKS GOOD AS SHOWERS AND THUNDERSTORMS ARE EXPECTED TO TRACK OVER THE BURN SCARS OF LAST YEARS FIRES IN SOUTHEAST MONTANA. MODELS ALL INDICATING OVER A HALF INCH OF PRECIPITATION IN THESE AREAS FROM LATE THIS AFTERNOON INTO THIS EVENING. WPC ALSO PROGGING NEARLY A HALF INCH OF QPF TODAY IN THESE AREAS AS WELL AS FROM LIVINGSTON TO BILLINGS. WILL KEEP FLASH FLOOD WATCH IN PLACE FOR PORTIONS OS SOUTHEAST MONTANA AS STRONG FORCING FROM UPPER TROUGH OF LOW PRESSURE MOVES IN OVER THE AREA. THERE MAY BE A NEED TO EXTEND THE FLASH FLOOD WATCH THROUGH SUNDAY MORNING BUT WILL EVALUATE THIS WITH THE AFTERNOON FORECAST PACKAGE. RICHMOND && .SHORT TERM...VALID FOR TDY AND SAT... BENEFICIAL MOISTURE IS ON THE WAY THE NEXT SEVERAL DAYS THANKS TO A 500-HPA TROUGH. UP TO AN INCH OF RAINFALL IS VERY POSSIBLE OVER MANY AREAS WHEN ALL IS SAID AND DONE...SO FORECAST POPS HAVE ONCE AGAIN BEEN LEVERAGED UPWARD WITH THIS FORECAST SO THAT 80 PERCENT PROBABILITIES OF MOISTURE ARE ADVERTISED IN AT LEAST SOME PERIODS OF THE FORECAST. HIGHS HAVE ALSO BEEN LOWERED TODAY AND SAT BASED ON EXPECTED CLOUD COVER AND PRECIPITATION. TODAY...DIFFLUENCE ASSOCIATED WITH A MODEST 300-HPA JET STREAK ON THE ORDER OF 60 TO 70 KT SHOULD HELP SHOWERS BLOSSOM ACROSS SOUTH CENTRAL MT THIS MORNING. BILLINGS MAY BE ON THE EAST EDGE OF THIS MOISTURE BASED ON RECENT RAP AND HRRR RUNS. THEN...BY AFTERNOON A DESTABILIZING BOUNDARY LAYER AND EASTWARD MOVEMENT OF THE DYNAMIC FORCING TIED TO THE UPPER-LEVEL JET SHOULD FOSTER CONVECTION EAST OF THE MORNING PRECIPITATION. THE 00 UTC GFS...ECMWF...AND RECENT RAP AND HRRR RUNS ALL AGREE WELL ON THIS NOTION. BOTH THE ARW AND NMM CORES OF THE HIGH-RESOLUTION...CONVECTION-ALLOWING WRF MODELS MAKING UP THE SPC STORM-SCALE ENSEMBLE OF OPPORTUNITY ALSO KEY IN ON THIS CONVECTION...WHICH SHOULD FORM SOMEWHERE ALONG A BILLINGS TO GREYBULL LINE IN THE 18 TO 21 UTC TIME FRAME. INSTABILITY WILL BE SUFFICIENT FOR AT LEAST EMBEDDED THUNDER...AND AS THE ACTIVITY GETS INTO SOUTHEASTERN MT...IT WILL HAVE ACCESS TO MUCAPE UPWARDS OF 1000 J/KG. GIVEN STEEPENING MID-LEVEL LAPSE RATES AND 50 KT OF 0-6 KM BULK SHEAR...THERE IS ENOUGH OF A RISK OF SEVERE STORMS IN THE BROADUS AND EKALAKA CORRIDOR IN PARTICULAR FOR US TO MAINTAIN A MENTION OF IT IN THE FORECAST. LARGE HAIL SHOULD BE THE PRIMARY THREAT. HOWEVER...QUESTIONS ABOUT DESTABILIZATION EXIST /WITH THE 00 UTC NAM SUGGESTING LOWER MUCAPE/ OWING TO CLOUD COVER...AND IT IS STILL POSSIBLE SHEAR WILL BE TOO STRONG FOR LONG-LIVED OR DEEP UPDRAFTS TO SUSTAIN THEMSELVES. NOTE THAT THERE IS A RISK OF SOME ISOLATED STORMS FORMING IN SOUTHEASTERN MT DURING PEAK HEATING IN ADVANCE OF THE ACTIVITY WE EXPECT TO MOVE INTO THAT AREA BY LATER IN THE AFTERNOON OR EVENING...THOUGH CONFIDENCE IN THAT IS LOW. TONIGHT...WE KEPT A MENTION OF SEVERE WEATHER IN THE FORECAST FOR FAR SOUTHEASTERN MT AND PARTS OF SHERIDAN COUNTY WY UNTIL 06 UTC. SREF-BASED SEVERE THUNDERSTORM PROBABILITIES SUGGEST THE RISK MAY CONTINUE /AT LEAST ON A MARGINAL BASIS/ FOR A WHILE AFTER SUNSET. OTHERWISE...OUR POP FORECAST IS BASED ON THE IDEA THAT A RELATIVE BREAK IN MORE WIDESPREAD PRECIPITATION COULD OCCUR AFTER ABOUT 06 UTC AS CONVECTION SHIFTS INTO THE DAKOTAS AND AS THE FORCING FROM THE 300-HPA JET SHIFTS INTO NORTHERN MT. THE 03 UTC SREF ARGUES A DIFFERENT STORY THOUGH SINCE IT BRINGS ANOTHER MORE DEFINED BATCH OF FORCING AND SHOWERS INTO SOUTH CENTRAL MT AFTER MIDNIGHT. THAT IS A GOOD EXAMPLE OF THE SUBTLE DETAILS THAT ARE STILL NOT WORKED OUT WITH THIS EVENT. BY SAT...CONFIDENCE IN THE FORECAST STARTS DECREASING A BIT SINCE GUIDANCE BEGINS SHOWING SOME DIFFERENCES IN HOW IT HANDLES ENERGY ASSOCIATED WITH THE MID- AND UPPER-LEVEL TROUGH. ADD TO THAT SOME GRID-SCALE FEEDBACK RELATED TO MODEL CONVECTIVE SCHEMES AND THERE ARE CERTAINLY UNCERTAINTIES TO CONTEND WITH. THE GFS SOLUTION WAS LEAST ROBUST WITH QPF OVER SOUTHERN MT...BUT IT ALSO SUFFERS MORE FROM GRID-SCALE FEEDBACK THAN MOST OTHER SOLUTIONS...AND IT LOOKS LIKE A RELATIVE OUTLIER. THE REST OF THE GUIDANCE IS WETTER...AND SO WE CAUTIOUSLY PUSHED POPS UPWARD ANOTHER NOTCH IN MANY PLACES. MID-LEVEL LAPSE RATES STAY MARGINALLY FAVORABLE FOR THUNDER...AND SO WE KEPT AT LEAST AN ISOLATED MENTION OF IT IN THE FORECAST FOR SAT AND SAT NIGHT. SCHULTZ .LONG TERM...VALID FOR SUN...MON...TUE...WED...THU... STILL SOME UNCERTAINTY ON WHETHER THE WET SCENARIO WILL HANG ON SUNDAY AND MONDAY. THE NAM AND ECMWF WERE INDICATING THAT IT WOULD AS THEY CUT A LOW OFF OVER WESTERN SOUTH DAKOTA AND VERY SLOWLY DRIFT IT EAST MONDAY. THIS WOULD WRAP SOME DECENT MOISTURE AROUND THE LOW INTO THE FORECAST AREA WITH STRONG UPSLOPE FLOW. THE GFS...ON THE OTHER HAND...MOVES THE UPPER LOW FARTHER EAST MUCH QUICKER. BOTH THE ECMWF AND GFS HAVE BEEN CONSISTENT WITH THEIR SOLUTIONS. DID RAISE POPS FOR SUNDAY AND MONDAY AS THE GFS WAS THE ODD MODEL OUT ON THE DRIER SIDE OF THINGS. DID LOWER TEMPERATURES SUNDAY AND MONDAY GOING WITH A WETTER SCENARIO. A BIT OF BLOCKING PATTERN SETS UP FOR WEDNESDAY THROUGH NEXT FRIDAY AS AN UPPER RIDGE PINCHES OFF FROM WYOMING INTO SOUTHERN CANADA. THE HIGH WILL BE PLACED BETWEEN THE UPPER LOW TO THE EAST AND ANOTHER MUCH DEEPER LOW MOVING INTO WASHINGTON. THE WESTERN UPPER LOW DOES NUDGE THINGS EAST WEDNESDAY AND PRODUCES SOUTHERLY FLOW OVER WYOMING AND MONTANA. ORDINARILY A SOUTH FLOW WOULD MEAN PRECIPITATION...BUT MODELS WERE PULLING IN DRIER MID LEVEL AIR. A SERIES OF WEAK SHORTWAVES SPIN OFF THE WESTERN LOW AND TRAVERSE THROUGH THE AREA THROUGH THE END OF THE EXTENDED FOR ASCENT. WILL HAVE TO LOOK OUT FOR LOW LEVEL MOISTURE INCREASING HOWEVER AS SOUTHEAST FLOW DEVELOPS OVER THE EASTERN HALF OF THE FORECAST AREA. WILL BROAD BRUSH LOW POPS FOR NOW AND WAIT AND SEE HOW THIS PATTERN PANS OUT. TWH && .AVIATION... SCATTERED SHOWERS THIS MORNING WILL BECOME MORE WIDESPREAD BY EARLY AFTERNOON. THERE WILL BE THUNDERSTORMS EMBEDDED WITHIN THE SHOWERS BUT THE MOST LIKELY LOCATION FOR ORGANIZED THUNDERSTORMS WILL BE EAST OF KBIL AND INTO SOUTHEAST MONTANA. SOME OF THE SHOWERS WILL CONTAIN MODERATE TO BRIEFLY HEAVY RAIN AND COULD LOWER CONDITIONS TO MVFR. SOME THUNDERSTORMS COULD BE QUITE STRONG FROM LOCATIONS EAST AND SOUTH OF A KSHR TO KMLS LINE WITH SOME HAIL. MOUNTAINS WILL BE OBSCURED. TWH/FRIEDERS && .PRELIMINARY POINT TEMP/POPS... TDY SAT SUN MON TUE WED THU ------------------------------------------------------- BIL 065 053/065 049/061 048/062 045/071 047/071 049/071 8/T 88/T 75/T 55/W 31/B 13/T 31/B LVM 061 043/063 043/057 040/059 037/066 041/071 040/067 8/T 88/T 84/T 55/W 31/B 23/T 33/T HDN 070 053/067 048/062 047/062 044/071 045/073 049/074 8/T 88/T 75/T 66/W 31/E 13/T 31/B MLS 072 055/068 049/065 049/062 046/068 046/071 050/071 6/T 88/T 75/T 65/W 53/W 23/T 32/T 4BQ 074 054/068 047/063 047/060 043/063 044/071 048/071 6/T 87/T 65/T 66/W 53/W 22/T 22/T BHK 071 053/068 047/062 047/060 043/061 043/067 048/067 5/T 77/T 65/T 65/W 53/W 22/W 22/T SHR 072 048/065 044/059 043/057 040/064 040/073 046/072 6/T 57/T 65/T 66/W 42/W 13/T 31/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT FOR ZONES 30-31-36>38-57-58. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
552 AM MDT FRI MAY 17 2013 .UPDATE... RECENT HIGH-RESOLUTION MODEL GUIDANCE CONTINUES TO SUPPORT STORMS FIRING OVER NORTH CENTRAL WY AND SOUTH CENTRAL MT THIS AFTERNOON. THERE IS A GROWING CONSENSUS FOR THE STORMS TO TRACK OVER SEVERAL OF THE BURN SCARS FROM THE 2012 WILDFIRES...WHICH POSES A RISK OF FLASH FLOODING AND DEBRIS FLOWS. SEVERAL DIFFERENT FLAVORS OF THE AVAILABLE HIGH-RESOLUTION GUIDANCE SHOW AN INCH OR MORE OF QPF IN PARTS OF SOUTH CENTRAL AND SOUTHEASTERN MT BETWEEN 21 AND 06 UTC. THAT IS A VERY REALISTIC POSSIBILITY EVEN WITH FAST STORM MOTIONS GIVEN PRECIPITABLE WATER VALUES NEAR AN INCH. THUS...WE DEEMED IT NECESSARY TO ISSUE A FLASH FLOOD WATCH FROM 18 UTC TODAY THROUGH 12 UTC SAT MORNING OVER THE BURN SCAR AREAS OF SOUTH CENTRAL AND SOUTHEASTERN MT. SOME PATCHY FOG IS ALSO OCCURRING AT BAKER AS OF 1145 UTC...SO AS LONG AS WE WERE UPDATING THE FORECAST...WE ADDED THAT IN UNTIL 15 UTC IN FAR SOUTHEASTERN MT. SCHULTZ && .SHORT TERM...VALID FOR TDY AND SAT... BENEFICIAL MOISTURE IS ON THE WAY THE NEXT SEVERAL DAYS THANKS TO A 500-HPA TROUGH. UP TO AN INCH OF RAINFALL IS VERY POSSIBLE OVER MANY AREAS WHEN ALL IS SAID AND DONE...SO FORECAST POPS HAVE ONCE AGAIN BEEN LEVERAGED UPWARD WITH THIS FORECAST SO THAT 80 PERCENT PROBABILITIES OF MOISTURE ARE ADVERTISED IN AT LEAST SOME PERIODS OF THE FORECAST. HIGHS HAVE ALSO BEEN LOWERED TODAY AND SAT BASED ON EXPECTED CLOUD COVER AND PRECIPITATION. TODAY...DIFFLUENCE ASSOCIATED WITH A MODEST 300-HPA JET STREAK ON THE ORDER OF 60 TO 70 KT SHOULD HELP SHOWERS BLOSSOM ACROSS SOUTH CENTRAL MT THIS MORNING. BILLINGS MAY BE ON THE EAST EDGE OF THIS MOISTURE BASED ON RECENT RAP AND HRRR RUNS. THEN...BY AFTERNOON A DESTABILIZING BOUNDARY LAYER AND EASTWARD MOVEMENT OF THE DYNAMIC FORCING TIED TO THE UPPER-LEVEL JET SHOULD FOSTER CONVECTION EAST OF THE MORNING PRECIPITATION. THE 00 UTC GFS...ECMWF...AND RECENT RAP AND HRRR RUNS ALL AGREE WELL ON THIS NOTION. BOTH THE ARW AND NMM CORES OF THE HIGH-RESOLUTION...CONVECTION-ALLOWING WRF MODELS MAKING UP THE SPC STORM-SCALE ENSEMBLE OF OPPORTUNITY ALSO KEY IN ON THIS CONVECTION...WHICH SHOULD FORM SOMEWHERE ALONG A BILLINGS TO GREYBULL LINE IN THE 18 TO 21 UTC TIME FRAME. INSTABILITY WILL BE SUFFICIENT FOR AT LEAST EMBEDDED THUNDER...AND AS THE ACTIVITY GETS INTO SOUTHEASTERN MT...IT WILL HAVE ACCESS TO MUCAPE UPWARDS OF 1000 J/KG. GIVEN STEEPENING MID-LEVEL LAPSE RATES AND 50 KT OF 0-6 KM BULK SHEAR...THERE IS ENOUGH OF A RISK OF SEVERE STORMS IN THE BROADUS AND EKALAKA CORRIDOR IN PARTICULAR FOR US TO MAINTAIN A MENTION OF IT IN THE FORECAST. LARGE HAIL SHOULD BE THE PRIMARY THREAT. HOWEVER...QUESTIONS ABOUT DESTABILIZATION EXIST /WITH THE 00 UTC NAM SUGGESTING LOWER MUCAPE/ OWING TO CLOUD COVER...AND IT IS STILL POSSIBLE SHEAR WILL BE TOO STRONG FOR LONG-LIVED OR DEEP UPDRAFTS TO SUSTAIN THEMSELVES. NOTE THAT THERE IS A RISK OF SOME ISOLATED STORMS FORMING IN SOUTHEASTERN MT DURING PEAK HEATING IN ADVANCE OF THE ACTIVITY WE EXPECT TO MOVE INTO THAT AREA BY LATER IN THE AFTERNOON OR EVENING...THOUGH CONFIDENCE IN THAT IS LOW. TONIGHT...WE KEPT A MENTION OF SEVERE WEATHER IN THE FORECAST FOR FAR SOUTHEASTERN MT AND PARTS OF SHERIDAN COUNTY WY UNTIL 06 UTC. SREF-BASED SEVERE THUNDERSTORM PROBABILITIES SUGGEST THE RISK MAY CONTINUE /AT LEAST ON A MARGINAL BASIS/ FOR A WHILE AFTER SUNSET. OTHERWISE...OUR POP FORECAST IS BASED ON THE IDEA THAT A RELATIVE BREAK IN MORE WIDESPREAD PRECIPITATION COULD OCCUR AFTER ABOUT 06 UTC AS CONVECTION SHIFTS INTO THE DAKOTAS AND AS THE FORCING FROM THE 300-HPA JET SHIFTS INTO NORTHERN MT. THE 03 UTC SREF ARGUES A DIFFERENT STORY THOUGH SINCE IT BRINGS ANOTHER MORE DEFINED BATCH OF FORCING AND SHOWERS INTO SOUTH CENTRAL MT AFTER MIDNIGHT. THAT IS A GOOD EXAMPLE OF THE SUBTLE DETAILS THAT ARE STILL NOT WORKED OUT WITH THIS EVENT. BY SAT...CONFIDENCE IN THE FORECAST STARTS DECREASING A BIT SINCE GUIDANCE BEGINS SHOWING SOME DIFFERENCES IN HOW IT HANDLES ENERGY ASSOCIATED WITH THE MID- AND UPPER-LEVEL TROUGH. ADD TO THAT SOME GRID-SCALE FEEDBACK RELATED TO MODEL CONVECTIVE SCHEMES AND THERE ARE CERTAINLY UNCERTAINTIES TO CONTEND WITH. THE GFS SOLUTION WAS LEAST ROBUST WITH QPF OVER SOUTHERN MT...BUT IT ALSO SUFFERS MORE FROM GRID-SCALE FEEDBACK THAN MOST OTHER SOLUTIONS...AND IT LOOKS LIKE A RELATIVE OUTLIER. THE REST OF THE GUIDANCE IS WETTER...AND SO WE CAUTIOUSLY PUSHED POPS UPWARD ANOTHER NOTCH IN MANY PLACES. MID-LEVEL LAPSE RATES STAY MARGINALLY FAVORABLE FOR THUNDER...AND SO WE KEPT AT LEAST AN ISOLATED MENTION OF IT IN THE FORECAST FOR SAT AND SAT NIGHT. SCHULTZ .LONG TERM...VALID FOR SUN...MON...TUE...WED...THU... STILL SOME UNCERTAINTY ON WHETHER THE WET SCENARIO WILL HANG ON SUNDAY AND MONDAY. THE NAM AND ECMWF WERE INDICATING THAT IT WOULD AS THEY CUT A LOW OFF OVER WESTERN SOUTH DAKOTA AND VERY SLOWLY DRIFT IT EAST MONDAY. THIS WOULD WRAP SOME DECENT MOISTURE AROUND THE LOW INTO THE FORECAST AREA WITH STRONG UPSLOPE FLOW. THE GFS...ON THE OTHER HAND...MOVES THE UPPER LOW FARTHER EAST MUCH QUICKER. BOTH THE ECMWF AND GFS HAVE BEEN CONSISTENT WITH THEIR SOLUTIONS. DID RAISE POPS FOR SUNDAY AND MONDAY AS THE GFS WAS THE ODD MODEL OUT ON THE DRIER SIDE OF THINGS. DID LOWER TEMPERATURES SUNDAY AND MONDAY GOING WITH A WETTER SCENARIO. A BIT OF BLOCKING PATTERN SETS UP FOR WEDNESDAY THROUGH NEXT FRIDAY AS AN UPPER RIDGE PINCHES OFF FROM WYOMING INTO SOUTHERN CANADA. THE HIGH WILL BE PLACED BETWEEN THE UPPER LOW TO THE EAST AND ANOTHER MUCH DEEPER LOW MOVING INTO WASHINGTON. THE WESTERN UPPER LOW DOES NUDGE THINGS EAST WEDNESDAY AND PRODUCES SOUTHERLY FLOW OVER WYOMING AND MONTANA. ORDINARILY A SOUTH FLOW WOULD MEAN PRECIPITATION...BUT MODELS WERE PULLING IN DRIER MID LEVEL AIR. A SERIES OF WEAK SHORTWAVES SPIN OFF THE WESTERN LOW AND TRAVERSE THROUGH THE AREA THROUGH THE END OF THE EXTENDED FOR ASCENT. WILL HAVE TO LOOK OUT FOR LOW LEVEL MOISTURE INCREASING HOWEVER AS SOUTHEAST FLOW DEVELOPS OVER THE EASTERN HALF OF THE FORECAST AREA. WILL BROAD BRUSH LOW POPS FOR NOW AND WAIT AND SEE HOW THIS PATTERN PANS OUT. TWH && .AVIATION... SCATTERED SHOWERS THIS MORNING WILL BECOME MORE WIDESPREAD BY EARLY AFTERNOON. THERE WILL BE THUNDERSTORMS EMBEDDED WITHIN THE SHOWERS BUT THE MOST LIKELY LOCATION FOR ORGANIZED THUNDERSTORMS WILL BE EAST OF KBIL. SOME OF THE SHOWERS WILL CONTAIN MODERATE TO BRIEFLY HEAVY RAIN AND COULD LOWER CONDITIONS TO MVFR. SOME THUNDERSTORMS COULD BE QUITE STRONG FROM LOCATIONS EAST AND SOUTH OF A KSHR TO KMLS LINE. MOUNTAINS WILL BE OBSCURED. TWH && .PRELIMINARY POINT TEMP/POPS... TDY SAT SUN MON TUE WED THU ------------------------------------------------------- BIL 065 053/065 049/061 048/062 045/071 047/071 049/071 8/T 88/T 75/T 55/W 31/B 13/T 31/B LVM 061 043/063 043/057 040/059 037/066 041/071 040/067 8/T 88/T 84/T 55/W 31/B 23/T 33/T HDN 070 053/067 048/062 047/062 044/071 045/073 049/074 8/T 88/T 75/T 66/W 31/E 13/T 31/B MLS 072 055/068 049/065 049/062 046/068 046/071 050/071 6/T 88/T 75/T 65/W 53/W 23/T 32/T 4BQ 074 054/068 047/063 047/060 043/063 044/071 048/071 6/T 87/T 65/T 66/W 53/W 22/T 22/T BHK 071 053/068 047/062 047/060 043/061 043/067 048/067 5/T 77/T 65/T 65/W 53/W 22/W 22/T SHR 072 048/065 044/059 043/057 040/064 040/073 046/072 6/T 57/T 65/T 66/W 42/W 13/T 31/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...FLASH FLOOD WATCH IN EFFECT FROM NOON MDT TODAY THROUGH LATE TONIGHT FOR ZONES 30-31-36>38-57-58. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
551 AM CDT FRI MAY 17 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 406 AM CDT FRI MAY 17 2013 ANOTHER SEASONABLY WARM AFTERNOON IS EXPECTED ACROSS THE REGION AS WEAK UPPER LEVEL RIDING WORKS ITS WAY IN FROM THE WEST. EARLY THIS MORNING...SOME SHOWER AND THUNDERSTORM ACTIVITY HAS DEVELOPED TO THE WEST OF THE LOCAL AREA...LIKELY A FACTOR OF THE LOW LEVEL JET PROVIDING JUST ENOUGH FORCING ACROSS WESTERN KANSAS EARLY THIS MORNING TO SPARK SOME CONVECTION. HOWEVER WITH THIS ACTIVITY SHOWING SIGNS OF DIMINISHING AND LITTLE INSTABILITY TO KEEP IT GOING AS IT APPROACHES THE LOCAL AREA...DECIDED TO JUST ADD A SLIGHT CHANCE OF SPRINKLES ACROSS THE WESTERN FRINGES OF OUR FORECAST AREA THROUGH 8 AM TO ACCOUNT FOR ANY REMNANTS OF THIS CONVECTION AS IT WORKS EAST. OTHERWISE...HAVE SEEN SOME PATCHY FOG DEVELOP ACROSS AROUND LXN AND ODX EARLY THIS MORNING AS TEMPERATURES HAVE FALLEN TO REACH THE DEWPOINTS AT THESE LOCATIONS THE PAST COUPLE OF HOURS...AND THINK SOME FURTHER DEVELOPMENT WILL BE POSSIBLE OVER THE NEXT FEW HOURS...GENERALLY WEST OF HIGHWAY 281. HRRR AND SREF HAVE BOTH BACKED OFF ON POTENTIAL FOG DEVELOPMENT FOR THIS MORNING...AND EXPECT ANY FOG THAT DOES MANAGE TO DEVELOP TO BE FAIRLY PATCHY AND SHORT LIVED...AND CORRESPONDINGLY TRIMMED BACK COVERAGE FROM PREVIOUS FORECAST. FOR THIS AFTERNOON...EXPECT TEMPERATURES TO CLIMB BACK INTO THE MID AND UPPER 80S ACROSS THE ENTIRE FORECAST AREA AS PARTLY CLOUDY TO MOSTLY SUNNY SKIES WILL WORK THEIR WAY IN ACROSS THE REGION AS THE RIDGE TRANSITIONS EASTWARD. ADDITIONALLY...WITH THE RIDGE AXIS MOVING OVERHEAD...850MB TEMPS WILL CLIMB A COUPLE OF DEGREES FROM YESTERDAYS VALUES...FURTHER AIDING IN A SEASONABLY WARM AFTERNOON. AT THE SURFACE...EXPECT A SURFACE TROUGH TO DEVELOP ON THE LEE SIDE OF THE ROCKIES BY EARLY AFTERNOON...AND THIS SHOULD HELP INCREASE THE PRESSURE GRADIENT JUST ENOUGH TO RESULT IN BREEZY SOUTHERLY WINDS...GENERALLY 15 TO 25 MPH IN MOST SPOTS. FOR TONIGHT...SOME OF THE GUIDANCE IS ATTEMPTING TO DEVELOP SOME CONVECTION ACROSS THE HIGH PLAINS AND TRANSITION IT EASTWARD AROUND SUNSET. WHILE THERE WILL BE PLENTY OF INSTABILITY TO JUSTIFY CONVECTION TO OUR WEST...A DECENT CAP IS FORECAST AROUND 800 MB WITH LITTLE IN THE WAY OF FORCING TO JUSTIFY MUCH CONVECTION ACROSS THE LOCAL AREA. EVEN SO...WITH 00Z WRF BEING THE MOST AGGRESSIVE TRANSLATING SOME OF THE REMNANTS OF THE HIGH PLAINS CONVECTION ACROSS THE LOCAL AREA DURING THE EVENING HOURS...FELT JUSTIFIED ADDING A FEW SPRINKLES TO THE NORTHWESTERN QUADRANT OF THE LOCAL AREA JUST IN CASE A FEW SHOWERS ARE ABLE TO MAINTAIN THEMSELVES AS THEY TRACK EAST. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 408 AM CDT FRI MAY 17 2013 THUNDERSTORM CHANCES THIS WEEKEND WILL BE THE PRIMARY FOCUS OF LONG TERM. IT SHOULD BE NOTED THAT THERE ARE CHANCES FOR PRECIPITATION NEARLY EVERYDAY OVER THE LONG TERM...BUT THE CHANCE FOR SEVERE THUNDERSTORMS APPEARS TO BE BEST ON SATURDAY AT THE MOMENT. AN UPPER LEVEL TROUGH WILL BEGIN TRANSITIONING OVER THE WEST COAST TODAY AND WILL EVENTUALLY MOVE EASTWARD INTO THE INTERMOUNTAIN WEST ON SATURDAY. AT THE SURFACE ON SATURDAY...A LEE LOW WILL FORM AHEAD OF THE UPPER LEVEL TROUGH...AND A COLD FRONT WILL DRAPE INTO NEBRASKA WHICH SHOULD HELP TO INITIATE THUNDERSTORMS ACROSS THE OUTLOOK AREA LATER IN THE AFTERNOON. THERE WILL BE A STRONG CAPPING INVERSION IN PLACE AT THE MID-LEVELS...SO THIS WILL NEED TO ERODE/BREAK BEFORE ANY CONVECTION CAN INITIALIZE. A FEW THINGS SHOULD HELP TO GET STORMS INITIATED LATER IN THE AFTERNOON THOUGH. FOR ONE...THE ADVECTION OF STEEPER LAPSE RATES IN THE MID-LEVELS WILL HELP WEAKEN THIS CAP. SECONDLY...THE COLD FRONT PROGGED TO SLIDE OVER THE REGION SHOULD SERVE AS A GOOD LIFTING MECHANISM TO HELP GET CONVECTION STARTED IN THE AFTERNOON. LASTLY...MODERATE TO STRONG INSTABILITY ON THE ORDER OF 3000-4000 J/KG OF MLCAPE IS FORECAST BY 00Z SUNDAY...SO ANY STORMS THAT DO FORM WILL HAVE THE ABILITY TO BECOME STRONG TO SEVERE. AS THE EVENT UNFOLDS LATER INTO THE EVENING...THE FORMATION ON AN MCS IS DEFINITELY POSSIBLY AND SHOULD POSE A PRIMARY THREAT OF DAMAGING WINDS. HAIL WILL BE THE PRIMARY THREAT EARLY IN THE EVENT...ESPECIALLY THE MORE ISOLATED/DISCRETE CELLS WITH STRONG UPDRAFTS. ITS ALSO WORTH NOTING THE NAM...GFS...AND EC ALL SHOW STRONG 0-1 KM BULK SHEAR ON THE ORDER OF 25 TO 30 KTS. DEEP LAYER SHEAR WAS NOT AS IMPRESSIVE BUT STILL HAD VALUES AROUND 35 KTS. THE SHEAR ENVIRONMENT COUPLED WITH STRONG INSTABILITY WOULD SUGGEST SUPERCELLS COULD FORM AND WITH ANY SUPERCELL...THERE WILL ALSO BE A TORNADO THREAT. MOVING INTO SUNDAY...THUNDERSTORMS WILL LIKELY CONTINUE MOVING EASTWARD ACROSS THE OUTLOOK AREA. THE SEVERE THREAT WILL BE OVERALL LIMITED...BUT OUR EASTERN COUNTIES COULD POTENTIALLY SEE THE SEVERE THREAT CONTINUE INTO THE AFTERNOON HOURS ON SUNDAY...PRIMARILY EAST OF HIGHWAY 281. NEXT WEEK WILL HAVE POPS ANYWHERE FROM 10 TO 30 PERCENT NEARLY EVERYDAY. THESE POPS ARE ROOTED IN THE TROUGH CURRENTLY OVER THE WEST COAST WHICH IS FORECAST TO MEANDER AROUND THE GREAT PLAINS NEXT WEEK. THE BIGGEST DISADVANTAGE IN THE LONG TERM IS THE LACK OF CONSISTENCY AND AGREEMENT BETWEEN THE MODELS. THROUGH THE WEEKEND...TEMPERATURES WILL BE ABOVE NORMAL...WHILE NEXT WEEK WILL BE CLOSER TO NORMAL FOR THIS TIME OF YEAR. HIGHS ON TUESDAY APPEAR TO BE THE ONE EXCEPTION...WITH TEMPERATURES MORE LIKELY TO BE SLIGHTLY BELOW NORMAL FOR THIS TIME OF YEAR. && .AVIATION...(FOR THE 12Z KGRI TAF THROUGH 12Z SATURDAY MORNING) ISSUED AT 550 AM CDT FRI MAY 17 2013 VFR CONDITIONS WILL PREVAIL AT KGRI FOR THE NEXT 24 HOURS. EXPECT THE MID LEVEL CLOUD DECK COVERING MUCH OF NEBRASKA EARLY THIS MORNING TO RAPIDLY SCATTER OUT OVER THE NEXT COUPLE OF HOURS AS SHORT WAVE RIDGING TRANSITIONS ACROSS THE PLAINS. OTHERWISE...EXPECT WINDS TO BE THE PRIMARY FOCUS...WITH THE PRESSURE GRADIENT ANTICIPATED TO TIGHTEN UP THE BY EARLY AFTERNOON AS A TROUGH OF LOW PRESSURE DEVELOPS ON THE LEE SIDE OF THE ROCKIES...SO WENT AHEAD AND INCLUDED WIND GUSTS TO 24KTS AFT 17/18Z. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...SAR LONG TERM...GUERRERO AVIATION...SAR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1036 AM EDT FRI MAY 17 2013 .SYNOPSIS... WARM TEMPERATURES WILL CONTINUE INTO EARLY NEXT WEEK AS BERMUDA HIGH PRESSURE REMAINS ANCHORED OFFSHORE. A MID LEVEL DISTURBANCE WILL BRING INCREASED CHANCES OF SHOWERS AND THUNDERSTORMS OVER THE WEEKEND INTO EARLY NEXT WEEK. DRIER WEATHER IS EXPECTED THROUGH THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 10:30 AM FRIDAY...ONLY FORECAST CHALLENGE IS POPS FOR THE LATE AFTERNOON/EVENING HOURS. 0600 GFS STILL SHOWS SOME LIMITED/SHALLOW ACTIVITY ACROSS THE PIEDMONT WHICH IS SEA BREEZE DRIVEN. FURTHER NORTH ACTIVITY APPEARS TO BE A LITTLE MORE ORGANIZED BUT FOR THE MOST PART IS NORTH OF OUR AREA. 0900 RAP GUIDANCE ONLY SHOWS THE ACTIVITY TO THE NORTH. OVERALL THERE IS NO REASON TO REMOVE SLIGHT CHANCE POPS BUT WITH THE 1200 UTC MHX SOUNDING SHOWING A CONVECTIVE TEMPERATURE OF 90 DEGREES F...IT WILL BE LATE. NO CHANGES TO TEMPERATURE FORECAST. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...WEAK PATTERN ALOFT COUPLED WITH BERMUDA HIGH AND PIEDMONT TROUGH WILL RESULT IN AFTERNOON SHOWERS AND THUNDERSTORMS SAT AND SUN. FOR SAT FLOW ALOFT REMAINS ZONAL AND FORECAST SOUNDINGS SHOW SOME DRY AIR THROUGH THE COLUMN. STILL ANTICIPATE SOME STORM DEVELOPMENT ALONG PIEDMONT TROUGH AND SEABREEZE BUT COVERAGE AND STRENGTH WILL BE LIMITED. COVERAGE SHOULD INCREASE SUN AS DEEPER MOISTURE ARRIVES AND WEAK 5H SHORTWAVE TROUGH SLOWLY MOVES INTO BUILDING MID LEVEL RIDGE. MID LEVEL LAPSE RATES REMAIN WEAK BUT FORECAST SOUNDINGS SHOW A SIGNIFICANT INCREASE IN MOISTURE WITH PRECIPITABLE WATER VALUES AROUND 1.9 INCH BY AFTERNOON. STEEP LOW LEVEL LAPSE RATES AND PRESENCE OF PIEDMONT TROUGH AND SEABREEZE HELP GENERATE CONVECTION. DEEPER MOISTURE AND ENHANCEMENT ALOFT WILL HELP SUSTAIN DEEPER CONVECTION RESULTING IN WIDESPREAD AFTERNOON SHOWERS AND THUNDERSTORMS. WEAK MID LEVEL LAPSE RATES...LIMITED DRY LOW LEVEL AIR AND LACK OF STRONG JETTING SUGGEST STORMS WILL NOT BECOME SEVERE. HIGHS WILL BE NEAR TO SLIGHTLY ABOVE CLIMO WITH WARM ADVECTION BEING OFFSET SOMEWHAT BY CLOUD COVER...ESPECIALLY ON SUN. LOWS WILL REMAIN SEVERAL DEGREES ABOVE CLIMO EACH NIGHT. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 3 AM FRIDAY...DEEP MOISTURE AND WEAKNESS IN BUILDING MID LEVEL RIDGE LINGERS OVER THE ARE MON...ONCE AGAIN CREATING AN ENVIRONMENT SUPPORTIVE OF WIDESPREAD SHOWERS AND THUNDERSTORMS. AS IS THE CASE ON SUN SEVERE PARAMETERS ARE LACKING SO STORMS ARE EXPECTED TO REMAIN SUB-SEVERE. PRECIP CHANCES START TO DECREASE TUE AS 5H RIDGE CONTINUES TO BUILD IN FROM THE EAST AND THE WEAKNESS IN THE RIDGE FILLS IN. REMAINDER OF THE PERIOD WILL BE DOMINATED BY THE 5H RIDGE AND THE BERMUDA HIGH. FORECAST SOUNDINGS SHOW DRY AIR BELOW 12FT TUE EXPANDING THROUGH THU AS SUBSIDENCE INVERSION STRENGTHENS. ABUNDANT MOISTURE ABOVE 15K FT MAY KEEP CIRRUS AROUND THROUGH THE PERIOD BUT PRECIP CHANCES WILL BE DIMINISHED. LATE IN THE PERIOD A COLD FRONT APPROACHES FROM THE NORTHWEST BUT ITS ARRIVAL WILL BE WELL BEYOND THE END OF THE PERIOD SO IT IS NOT A FACTOR AT THIS POINT. HIGHS WILL BE WITHIN A FEW DEGREES OF CLIMO MON AND TUE BUT CLIMB WELL ABOVE CLIMO BY THE END OF THE PERIOD. LOWS WILL REMAIN WELL ABOVE CLIMO THROUGH THE PERIOD. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... AS OF 12Z...ANOTHER HOUR OR TWO OF PATCHY FOG THIS MORNING INLAND...WITH THE POTENTIAL FOR FOG AGAIN SATURDAY MORNING. OTHERWISE EXPECT VFR. MID TO HIGH CLOUDS LINGERING ACROSS THE AREA THIS MORNING...WITH TEETERING MVFR/IFR FOG AT KLBT. EXPECT FOG TO DISSIPATE WITHIN THE NEXT HOUR OR TWO...GIVING WAY TO VFR AREA-WIDE FOR THE REST OF THE DAY WITH SCT/BKN MID TO HIGH LEVEL CLOUDS. SOUTHWEST WINDS AOB 10 KTS EXPECTED TODAY...BECOMING SOUTH ALONG THE COAST WITH THE AFTERNOON SEABREEZE. WOULD NOT COMPLETELY RULE OUT AN ISOLATED SHOWER OR THUNDERSTORM THIS AFTERNOON...BUT CONFIDENCE IS LOW. INTO THE OVERNIGHT HOURS...CLOUD COVERAGE WILL CONTINUE...AND LIKELY INCREASE...WITH WINDS BECOMING LIGHT. TOWARDS THE EARLY MORNING HOURS ON SATURDAY...CANNOT RULE OUT PATCHY FOG...ESPECIALLY INLAND. EXTENDED OUTLOOK...CHANCE OF AFTN SHOWERS/TSTMS SATURDAY THROUGH MONDAY...OTHERWISE VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 10:30 AM FRIDAY...LATEST BUOY OBSERVATIONS SHOW FORECAST IS ON TRACK. NO CHANGES WARRANTED. SUMMERTIME PATTERN REMAINS IN FULL FORCE WITH A SOUTHWEST FLOW OF 10-15 KNOTS AND SEAS OF 2-4 FEET. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...SOUTHWEST FLOW WILL CONTINUE THROUGH THE PERIOD AS BERMUDA HIGH REMAINS IN CONTROL. GRADIENT WILL PRODUCE SPEEDS IN THE 10 TO 15 KT RANGE WITH SPEEDS EACH AFTERNOON ON THE HIGHER END OF THE RANGE. SEAS WILL RUN 2 TO 4 FT WITH SOUTHEAST SWELL BECOMING A LITTLE MORE APPARENT. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 3 AM FRIDAY...SUMMER PATTERN CONTINUES WITH BERMUDA HIGH KEEPING SOUTH TO SOUTHWEST FLOW BETWEEN 10 AND 15 KT. HIGHEST SPEEDS WILL OCCUR IN THE AFTERNOON. SEAS 2 TO 4 FT THROUGH THE PERIOD WILL BE A MIX OF WIND WAVE AND SOUTHEAST SWELL. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...SHK NEAR TERM...SHK SHORT TERM...III LONG TERM...III AVIATION...SGL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1006 AM EDT FRI MAY 17 2013 .SYNOPSIS... A COLD FRONT OVER THE OHIO VALLEY AND MID ATLANTIC WILL GRADUALLY MOVE SOUTH INTO OUR REGION WHILE AN UPPER LEVEL LOW PRESSURE SYSTEM MOVES IN FROM THE WEST. BOTH THE FRONT AND THE UPPER LEVEL LOW WILL LINGER AROUND OUR AREA THROUGH THE WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH SATURDAY/... AS OF 1005 AM FRIDAY... REST OF TODAY: THE LATEST SURFACE ANALYSIS SHOWED A NEARLY STATIONARY FRONT OVER THE OHIO VALLEY INTO THE MID ATLANTIC...WITH THE EASTERN PART OF THE FRONT OFFSHORE SAGGING SOUTH EAST OF NORFOLK BENEATH HIGH PRESSURE. A SURFACE TROUGH WAS LOCATED OVER THE FOOTHILLS AND WESTERN PIEDMONT...WHILE A WEAKENING OUTFLOW BOUNDARY WHICH TURNED MANY WINDS TO THE NORTH AND NORTHEAST NORTH OF ABOUT U.S. 64 WAS PRETTY DIFFUSE. SKIES HAD CLEARED ACROSS MUCH OF CENTRAL NORTH CAROLINA BEHIND A MID-LEVEL SHORTWAVE MOVING THROUGH THE AREA...WITH THE SHORT-TERM GUIDANCE CONTINUING TO FORECASDT MID-LEVEL RIDGING IN PLACE COINCIDENT WITH THE 12Z UPPER-AIR ANALYSIS. FOR THE AFTERNOON...IT WILL BE INTERESTING TO SEE HOW SURFACE DEW POINTS REACT TO MIXING...AS THE RAP IS VERY AGGRESSIVE DRYING SURFACE DEW POINTS OVER THE WESTERN PIEDMONT ALMOST INTO THE 40S... WHILE THE NAM AND GFS MAINTAIN MUCH HIGHER DEW POINTS...AT LEAST WELL INTO THE 50S. A COUPLE OF THINGS ARE IN FAVOR OF THE RAP... WITH A RELATIVE MINIMUM OF DEW POINTS ALREADY OVER THE FOOTHILLS AND WESTERN PIEDMONT...AND THE RECENT TRACK RECORD OF GUIDANCE OVER THE LAST 24 HOURS BEING MUCH TOO AGGRESSIVE WITH THE MOISTURE INCREASE IN THE AIR MASS OVER CENTRAL NORTH CAROLINA. IN FACT...PRECIPITABLE WATER VALUES WERE ONLY AROUND AN INCH AT BOTH KGSO AND KRNK... COMPARED TO THE NEARLY 1.5 INCHES FORECAST BY THIS TIME BY THE GUIDANCE DURING THE DAY THURSDAY. EVEN ON THE MORE MOIST BUFR SOUNDINGS OF THE NAM AND GFS...MODEST CAPPING EXISTS AROUND 750MB... PARTICULARLY ON THE GFS. WITH LIMITED FORCING ALOFT...THINK ANY DEEP CONVECTION WILL NEED TO GENERATE OUTSIDE OF CENTRAL NORTH CAROLINA AND MOVE IN...DELAYING CHANCES AND PUSHING THEM A LITTLE FARTHER NORTH. THE LATEST HRRR WRF SHOWS ONLY SPOTTY PRECIPITATION NORTH OF ABOUT U.S. 64 AFTER 20Z...AND THE LOCAL WRF IS VERY SIMILAR. RAISED MAXES ABOUT A DEGREE IN MOST LOCATIONS GIVEN MORE SUN...TWO TO THREE DEGREES OVER THE SOUTHWEST PIEDMONT IN EXPECTED DRIER CONDITIONS AND MORE SUN. -DJF TONIGHT: WITH WEAK S/W RIDGING HOLDING ON ACROSS THE AREA TONIGHT... EXPECT ANY AFTERNOON AND EVENING SHOWERS/STORMS SHOULD DWINDLE WITH NOCTURNAL COOLING AND RESULTANT STABILIZATION OF THE BOUNDARY LAYER. THUS... WILL TREND POPS TO A SLIGHT CHANCE AFTER MIDNIGHT. CANNOT RULE OUT ANY LOCALIZED AREA OF FOG AND LOW CLOUDS DEPENDING ON IF AND WHERE ANY LOCALIZED HEAVY PRECIP FALLS TODAY. EXPECT LOW TEMPS TONIGHT WILL AGAIN BE ABOVE NORMAL IN THE MID TO UPPER 60S. SATURDAY: THE WEAK MID LEVEL LOW OVER THE OZARKS THIS MORNING WILL CONTINUE SLOWLY SHIFT EASTWARD ON SATURDAY WHILE OPENING UP AND WEAKENING... WHILE MOVING INTO THE CENTRAL AND SOUTHERN APPALACHIANS. BOTH THE GFS AND ECMWF DEPICT THIS DISTURBANCE SHOULD BE CLOSE ENOUGH TO THE AREA TO SUPPORT HIGHER POPS ON SATURDAY (WITH THE NAM TRYING TO HOLD IT OFF MORE). THUS... WILL CONTINUE TO GO WITH A WETTER SOLUTION. MLCAPE VALUES ARE EXPECTED TO TOP OUT IN THE 1500 TO 2000 J/KG RANGE ACROSS THE PIEDMONT. STILL DEEP LAYER SHEAR WILL REMAIN WEAK (LESS THAN 20 KTS AGAIN)... RESULTING IN A LOW SEVERE POTENTIAL AGAIN. HOWEVER... WE MAY HAVE A LOCALIZED FLOODING THREAT WITH THE EXPECTED SLOW MOTION OF THE SHOWERS/STORMS AND EXPECTED GREATER COVERAGE. THUS... WILL HIGHLIGHT THIS THREAT FOR LOCALIZED FLOODING/EXCESSIVE RAINFALL IN THE HWO. HIGHS SATURDAY WILL BE LOWER WITH THE FRONT TO THE NORTH TRYING TO OOZE DOWN INTO NORTHERN PORTIONS OF OUR AREA AND GREATER COVERAGE OF SHOWERS AND STORMS. THUS WILL GO WITH UPPER 70S NORTH TO MID 80S SOUTH. EXPECT THE BEST COVERAGE OF SHOWERS AND STORMS WILL AGAIN BE ACROSS THE NORTHERN HALF OF THE AREA... CLOSER TO THE BEST SURFACE CONVERGENCE. THUS.. WILL GO WITH LIKELY POPS NORTH TO CHANCE SOUTH. -BSD && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... AS OF 301 AM FRIDAY... WET AND UNSETTLED PERIOD SETTING UP FOR CENTRAL NC WITH A POSSIBILITY OF LOCALLY EXCESSIVE RAINFALL. SATURDAY NIGHT INTO SUNDAY...MODELS IN GOOD CONSENSUS WITH AN UPPER LEVEL LOW OVER THE LOWER OH VALLEY SATURDAY EVENING DRIFTING SLOWLY SEWD INTO EASTERN KY BY SUNDAY AFTERNOON. MEANWHILE A STALLED SFC BOUNDARY WILL STRETCH WEST-TO-EAST IN VICINITY OF THE NC/VA BORDER. THE APPROACH OF THE UPPER LEVEL LOW WILL INCREASE LOW LEVEL SLY FLOW...MADE EVIDENT BY 850MB FLOW INCREASING FROM 15 KTS SATURDAY EVENING TO 25-30KTS BY SUNDAY EVENING. THIS FLOW WILL PUMP MOISTURE OFF THE ATLANTIC AND EASTERN GULF INTO THE CAROLINAS...INCREASING PRECIPITABLE WATER VALUES TO AS HIGH AS 1.75 INCHES BY SUNDAY EVENING. THE UPPER LEVEL LOW WILL ALSO INCREASE MID-UPPER DIVERGENCE OVER THE REGION. THUS THE COMBINATION OF INCREASING LOW LEVEL CONVERGENCE...INCREASING DIVERGENCE ALOFT...AND A VERY MOIST AIR MASS WILL SUSTAIN SCATTERED SHOWERS ACROSS THE REGION SATURDAY NIGHT...MAINLY NORTH AND WEST...AND LEAD TO THE DEVELOPMENT OF NUMEROUS SHOWERS AND A FEW T-STORMS SUNDAY AFTERNOON-SUNDAY NIGHT. WILL MAINTAIN LIKELY POPS ACROSS THE NORTH HALF FOR NORTH WITH SOLID CHANCE POPS SOUTH-SOUTHEAST. MAX TEMPS SUNDAY WILL BE AFFECTED BY OVERCAST SKIES AND NUMEROUS SHOWERS. MAX TEMPS LOWER 80S SOUTH-SOUTHEAST TO THE UPPER 70S NORTH. SUNDAY NIGHT THROUGH MONDAY NIGHT...UPPER LEVEL LOW SLOWLY OPENS UP AND DRIFTS EAST ACROSS THE FORECAST AREA DURING THIS TIME. ASSOCIATED MID LEVEL TROUGH WILL ALSO DRIFT EAST WITH TIME BUT HELP TO FOCUS MOST OF THE SHOWERS AND SCATTERED T-STORMS ALONG AND EAST OF HIGHWAY 1 BY MONDAY AFTERNOON. STALLED SFC BOUNDARY IN VICINITY OF THE VA BORDER WILL CONTINUE TO SERVE AS A FOCUS FOR LOW LEVEL CONVERGENCE AND MOISTURE POOLING. THUS STILL FAVOR HIGHER POPS (LIKELY) ACROSS THE NORTH-NORTHEAST THIS PERIOD...TRENDING TO HIGH CHANCE OR LOW END LIKELY SOUTH. MONDAY MAX TEMPS AGAIN HAMPERED BY EXTENSIVE CLOUDINESS AND SCATTERED-NUMEROUS SHOWERS. MAX TEMPS UPPER 70S/NEAR 80 NORTH TO LOWER 80S SOUTH. MIN TEMPS MID 60S. PRESENCE OF THE STALLED SFC BOUNDARY ACROSS THE NORTH WILL AID TO FOCUS MOST OF THE SHOWER DEVELOPMENT. WITH PRECIP WATER VALUES AROUND 1.6-1.75 INCHES LATE SATURDAY THROUGH MONDAY NIGHT...SHOWERS AND STORMS WILL BE EFFICIENT RAIN PRODUCERS. HPC HAS AN AREA OF THE NC PIEDMONT AND SOUTHERN VA OUTLINED FOR THE POSSIBILITY OF EXCESSIVE RAINFALL WITH AMOUNTS IN EXCESS OF 3 INCHES (EQUIVALENT TO A MONTHS WORTH OF RAIN) POSSIBLE NEAR THE VIRGINIA BORDER LATE SATURDAY THROUGH MONDAY EVENING. CURRENTLY...WENT A BIT MORE CONSERVATIVE AND HAVE STORM TOTAL PRECIP AMOUNTS 2-2.5 INCHES IN THIS REGION. HOWEVER THIS SET-UP USUALLY LEAD TO LOCALLY EXCESSIVE RAINFALL SO COULD SEE HIGHER AMOUNTS IN THIS REGION. PLAN TO MENTION THREAT FOR LOCALLY EXCESSIVE RAINFALL IN THE HAZARDOUS WEATHER OUTLOOK. && .LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 301 AM FRIDAY... TUESDAY THROUGH WEDNESDAY...WEAK SUBSIDENCE BEHIND THE EXITING MID/UPPER LEVEL TROUGH WILL AID TO DRY OUT THE AIR MASS. A SLIGHTLY MORE STABLE AND DRIER AIR MASS WILL LEAD TO FEWER SHOWERS AND STORMS IN THE AFTERNOON. IN ADDITION...THIS WILL LEAD TO WARMER AFTERNOON TEMPS. WILL MAINTAIN A SLIGHT CHANCE POP EVERYWHERE TO COVER THREAT OF AFTERNOON CONVECTION WHILE MAX TEMPS WILL BE REFLECTIVE OF THE EARLY SUMMER PATTERN IN THE LOW-MID 80S. BY THURSDAY...GFS MUCH MORE AGGRESSIVE WITH ITS EWD MOVEMENT OF A S/W TROUGH AND ASSOCIATED SFC FRONT INTO THE MID ATLANTIC AND CAROLINAS. ECMWF MUCH SLOWER WITH BEST UPPER SUPPORT OVER THE GREAT LAKES AND LOWER OH VALLEY. FAVOR THE SLOWER ECMWF AT THIS TIME. THUS...WILL LOWER POPS THURSDAY FROM PREVIOUS FORECAST WITH SLIGHT CHANCE OF AFTERNOON CONVECTION AND HIGHS TEMPS SOLIDLY IN THE MID 80S. MIN TEMPS THROUGH THE PERIOD MAINLY IN THE MID 60S. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... AS OF 1005 AM FRIDAY... MAINLY VFR CONDITIONS WILL PREVAIL THROUGH THE 12Z TAF PERIOD. THE POSSIBLE EXCEPTION WILL RESULT FROM ISOLATED-TO-SCATTERED SHOWERS AND STORMS MAINLY FOCUSED LATE THIS AFTERNOON FROM TRIAD TERMINALS TO KRDU AND KRWI AND POSSIBLY SOME LOW STRATUS AND/OR FOG IN THE PRE-DAWN HOURS OF SATURDAY. WILL KEEP ONLY VICINITY SHOWERS MENTIONED IN THE TAFS FROM THIS AFTERNOON INTO THE EVENING...GIVEN BOTH THE TIMING AND COVERAGE UNCERTAINTY WITH ANY SHOWERS AND STORMS. WILL GO WITH A LIGHT AND VARIABLE WIND ACROSS THE THE NORTHERN TAF SITES... WITH MORE OF A SOUTHWESTERLY WIND AT KFAY THROUGH EARLY AFTERNOON... BEFORE OUTFLOW FROM ANY SHOWERS AND STORMS TO THE NORTH MAY RESULT IN VARIABLE WINDS FOR KFAY AS WELL. EXPECT THE BULK OF THE PRECIP TO DISSIPATE AND DWINDLE IN COVERAGE LATE THIS EVENING WITH THE LOSS OF DAYTIME HEATING. WE MAY SEE SOME PATCHY FOG AND/OR LOW STRATUS DEVELOP TONIGHT ACROSS THE AREA. HOWEVER...WILL NOT MENTION ANY RESTRICTIONS IN THE TAFS AT THIS TIME GIVEN THE SUB-VFR CONDITIONS WILL BE DRIVEN BY WHERE THE RAIN FALLS AND THE AMOUNT OF MID AND HIGH LEVEL CLOUD COVER STREAMING INTO THE AREA FROM THE WEST. LOOKING AHEAD: AS A COLD FRONT APPROACHES FROM THE NORTH...AND AN UPPER-LEVEL LOW APPROACHES FROM THE WEST...THE CHANCES FOR UNSETTLED WEATHER INCREASE. SCATTERED-TO-NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED OVER THE WEEKEND. SCATTERED SHOWERS AND THUNDERSTORMS SHOULD CONTINUE EARLY NEXT WEEK AS WELL. THE CHANCE FOR LATE NIGHT AND EARLY MORNING LOW CLOUDS AND FOG WILL INCREASE INTO THE WEEKEND AND EARLY NEXT WEEK IN A MOIST AIR MASS AS WELL. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS/DJF NEAR TERM...DJF/BSD SHORT TERM...WSS LONG TERM...WSS AVIATION...BSD/MWS/DJF
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1035 AM CDT FRI MAY 17 2013 .UPDATE... 12Z FWD SOUNDING DEPICTS NEARLY DRY ADIABATIC LAPSE RATES FROM 850MB UP TO 500MB. CURRENTLY A WEAK SHORTWAVE WAS MOVING ACROSS NORTH TEXAS IN NORTHWEST FLOW ALOFT AND WAS RESPONSIBLE FOR THE ELEVATED CONVECTION OCCURRING OVER THE SOUTHEAST ZONES THIS MORNING. THESE STORMS HAVE PRODUCED HAIL UP TO GOLF BALL SIZE AND ARE A TESTAMENT TO THE STEEP LAPSE RATES ALOFT. THIS SHORTWAVE WILL CONTINUE TO MOVE SOUTHEAST AND OUT OF THE AREA BY MIDDAY. STRONG SURFACE HEATING ACROSS THE WESTERN ZONES WILL HELP PUSH TEMPERATURES TO NEAR THE CENTURY MARK THIS AFTERNOON. A DRY LINE WILL REACH A LINE FROM GRAHAM TO COMANCHE TO LLANO. SHORT TERM MODELS DEPICT DEWPOINTS IN THE LOW TO MID 70S AHEAD OF THE DRY LINE...BUT THIS IS PROBABLY TOO HIGH. BELIEVE DEWPOINTS WILL MIX OUT INTO THE UPPER 60S. NONETHELESS...THIS WILL CONTRIBUTE TO EXTREME INSTABILITY WITH SURFACE BASED CAPE VALUES ABOVE 4000 J/KG. UNLIKE THE EVENT ON WEDNESDAY...THE CAP WILL BE MUCH STRONGER TODAY AND WILL REQUIRE STRONG HEATING AND THE MESOSCALE FORCING PROVIDED BY A DRY LINE TO BE OVERCOME. GIVEN A REASONABLE FORECAST TEMP/DEWPOINT COMBINATION OF 99 OVER 68 AHEAD OF THE DRY LINE...THIS SHOULD BE SUFFICIENT FOR THE CAP TO BREAK. SEVERAL OF THE HI-RES CONVECTION ALLOWING MODELS AND THE LAST 2 RUNS OF THE NAM ARE SHOWING STORM INITIATION LATE THIS AFTERNOON...AND ARE FOCUSING IN ON THE AREA NEAR THE LLANO UPLIFT...WHICH WOULD AFFECT OUR SW ZONES AND ALSO ANOTHER AREA NEAR GRAHAM AND BRECKENRIDGE. DEEP LAYER SHEAR IS NOT OVERLY STRONG AND IS ON THE LOW END OF THE ALLOWABLE LEVEL FOR SUPERCELLS. HOWEVER THE HIGH INSTABILITY WILL LIKELY COMPENSATE AND ALLOW FOR SUPERCELL MODES. SUPERCELL STORM MOTION TECHNIQUES BASED ONLY ON WIND PROFILES ARE EAST AT 10KT...BUT IN CASES OF HIGH INSTABILITY AND WEAK FLOW...THESE SUPERCELLS WILL LIKELY HEAD SLOWLY SOUTHEAST OR EVEN DUE SOUTH. GIANT HAIL...PERHAPS GREATER THAN BASEBALLS WILL BE POSSIBLE WITH ANY SUPERCELL STORM. SURFACE TEMPS WILL LIKELY REACH 105 WEST OF OUR CWA BEHIND THE DRY LINE...WHICH SHOULD ALLOW A THERMAL SURFACE LOW TO INTENSIFY TODAY. THIS WILL CAUSE LOW LEVEL WINDS TO BACK OVER THE NORTHERN PART OF THE CWA...WHICH WILL ENHANCE LOW LEVEL DIRECTION SHEAR PROFILES ACROSS THE NORTHWEST CWA DESPITE WIND SPEEDS REMAINING FAIRLY WEAK AND LESS THAN 15KT AT ANY GIVEN LEVEL. STORM RELATIVE 0-3KM HELICITY VALUES BY THE RUC/NAM ARE FORECAST TO BE NEAR 100-150 MS/S2...SIGNIFICANTLY LESS THAN LAST WEDNESDAY...BUT AGAIN THE HIGHER INSTABILITY CAN OFTEN COMPENSATE TO RAISE THE CONCERN FOR TORNADOGENESIS. IN ADDITION SHOULD SUPERCELLS IN FACT MOVE SOUTH...THESE MODEL VALUES OF 0-3 SRH VALUES ARE TOO LOW. HAVE ADDED A RISK OF ISOLATED TORNADOES TO THE HWO AND GRAPHIC FORECASTS AS WELL. I SHOULD STRESS ALL OF THE SEVERE THREAT TODAY IS CONDITIONAL BASED ON THE CAP BREAKING...WHICH AGAIN IS NOT GARAUNTEED BUT IS PROBABLE. WITH LESS HEATING ACROSS THE I-35 CORRIDOR...THIS SHOULD KEEP SEVERE CONVECTION CONFINED TO THE WESTERN ZONES WITH THE CAP TOO STRONG FOR SURFACE BASED CONVECTION IN THE CENTRAL AND EASTERN ZONES. STILL IT IS POSSIBLE RESIDUAL ELEVATED CONVECTION OR ANVIL PRECIPITATION MAY ENTER THE CENTRAL ZONES LATE TONIGHT...BUT WILL KEEP POPS AT 10 PERCENT WITH NO MODEL SUPPORT FOR THIS SCENARIO. FOR THE UPDATE HAVE LOWERED HIGHS IN THE SOUTHEAST ZONES DUE TO MORNING RAIN AND CLOUDS. HAVE RAISED POPS IN THE WESTERN ZONES TO REFLECT THE HIGHER POTENTIAL FOR STORMS THIS AFTERNOON AND EVENING. TR.92 && .PREV DISCUSSION... /ISSUED 354 AM CDT FRI MAY 17 2013/ ...A FEW SEVERE STORMS POSSIBLE ACROSS FAR WESTERN NORTH TEXAS BY EACH EVENING TODAY AND SATURDAY...THEN NORTH OF I-20 LATE SUNDAY... WEATHER FORECAST REMAINS CHALLENGING TODAY INTO THE WEEKEND. WE CONTINUED TO SEE A SUBTLE SURFACE BOUNDARY SITUATED ALONG/NORTH OF HWY 38 THIS MORNING AS EVIDENCED BY THE BACKED/LIGHTER EAST WINDS AND LOWER SURFACE DEW POINTS THIS MORNING...WHILE STRONGER SSE WINDS 10 TO 15 MPH WHERE OCCURRING FROM THE I-20 CORRIDOR INTO CENTRAL TEXAS. SOME PATCHY DENSE FOG WAS OCCURRING ALONG THE RED RIVER VALLEY...WHILE A SUBTLE DISTURBANCE WAS MOVING ACROSS WITHIN THE UPPER RIDGE OVER THE TOP OF THE AREA. SOME AC/ACCAS WAS NOTED ON INFRARED SATELLITE IMAGERY WITH STEEP LAPSE RATES ALOFT ON THE 00Z FWD SOUNDING AND MODELS. ISOLATED...ELEVATED/HIGH-BASED SHOWERS AND STORMS ARE POSSIBLE THIS MORNING MAINLY ALONG AND SOUTH OF THE I-20/I-30 CORRIDORS. LIGHTNING WILL BE THE MAIN THREAT WITH ACTIVITY THIS MORNING WITH VERY LITTLE IN THE WAY OF MEASURABLE RAINFALL EXPECTED. THE SURFACE DRYLINE AND ASSOCIATED LOW PRESSURE OVER FAR WEST TEXAS WILL CONTINUE TO DEEPEN AND SLIDE SLOWLY EAST TOWARD OUR FAR W/SW COUNTIES LATE THIS AFTERNOON/EVE. STRONG MIXING AND HEATING ALONG AND JUST AHEAD OF THIS FEATURE WILL HELP HIGHS SOAR WELL INTO THE 90S WITH A FEW AREAS TOPPING THE CENTURY MARK WEST OF I-35/I-35W. OUR CAPPING INVERSION WAS ELEVATED AND BASED ABOVE 800MB AND NOT OVERLY STOUT...SO DESPITE THE UPPER RIDGE ARRIVING OVERHEAD...FEEL THE HOT TEMPS WILL MAKE IT BREAKABLE. HIGH-RES WRF/ARW/AND HRRR MODELS ALL HINT AT ISOLATED STORM DEVELOPMENT JUST W/SW OF OUR CWA AT PEAK HEATING AND POTENTIALLY AFFECTING OUR FAR WSW COUNTIES BETWEEN 4 PM AND SUNSET. INSTABILITY WILL BE VERY HIGH WITH MODELS SHOWING 3500-5000 J/KG SBCAPE OR POSSIBLY MORE WITH VERY STEEP MID LEVEL LAPSE RATES OVER 8 DEG C/KM. ANY ISOLATED STORMS THAT OCCUR WILL LIKELY BE SEVERE WITH VERY LARGE HAIL AND DAMAGING DOWNBURSTS. DESPITE SURFACE DEW POINTS BEING NEAR 70 DEGREES...THE HOT TEMPERATURES WILL RESULT IN RELATIVELY HIGH BASES AND A LOWER TORNADO THREAT THAN A FEW DAYS AGO. WITH THE UPPER RIDGE OVERHEAD...STORMS WILL DIMINISH IN STRENGTH OR DISSIPATE RAPIDLY AROUND SUNSET WITH LOSS OF HEATING AND THE CAP INTENSIFYING QUICKLY BY LATE EVENING. THE UPPER RIDGE SHIFTS EAST OF THE AREA ON SATURDAY WITH LONGWAVE UPPER TROUGH SNAKING OVER THE ROCKIES INTO THE WESTERN HIGH PLAINS. THE DRYLINE WILL ACTUALLY MAKE A STRONGER PUSH TOWARD OUR FAR WESTERN COUNTIES BY EARLY EVENING SATURDAY WITH A LITTLE BETTER UPPER SUPPORT. INSTABILITY WILL BE VERY STRONG ONCE AGAIN WITH ISOLATED TO SCATTERED STRONG TO SEVERE STORMS EXPECTED MAINLY ALONG AND WEST OF HWY 281...THEN DIMINISHING QUICKLY AFTER SUNSET WITH THE CAP INTENSIFYING ONCE AGAIN. THE UPPER TROUGH DAMPENS OVER THE CONUS ON SUNDAY WITH STRONG WESTERLY FLOW ALOFT OCCURRING FROM THE RED RIVER VALLEY NORTH THROUGH THE CENTRAL PLAINS. HAVE MODIFIED BEST CHANCES TO OCCUR NORTH OF I-20 AND INTO THE RED RIVER VALLEY...WITH THE CAP BEING MUCH STRONGER OVER THE SOUTH. DIURNAL SEVERE WEATHER WILL BE POSSIBLE AGAIN...BUT CONFIDENCE IS LOWER FOR LATE SUNDAY DUE TO UNCERTAINTIES REGARDING CAP STRENGTH AND SOUTHERN EXTENT OF FORCING. THE BEST SURFACE FOCUS WILL BE ALONG A COLD FRONT THAT IS EXPECTED TO BE WELL TO THE NORTHWEST OF THE AREA AS WELL. OTHERWISE IN THE EXTENDED...STAYED WITH PERSISTENCE WITH THE PREVIOUS FORECAST WITH LOW POPS RETURNING BY MID WEEK WITH A COLD FRONT WEAKENING AND STALLING ACROSS THE NORTHWEST COUNTIES. A SHORTWAVE TROUGH WILL BE MOVING OVER THE CENTRAL AND SOUTHERN PLAINS AT THIS TIME AS WELL. IT IS TOO EARLY TO ASSESS ANY SEVERE WEATHER THREAT THIS FAR OUT...BUT WILL CONTINUE TO ASSESS THESE POSSIBILITIES IN THE COMING DAYS AHEAD. 05/ && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 89 72 93 72 88 / 10 10 5 10 10 WACO, TX 91 71 92 71 90 / 10 10 5 10 10 PARIS, TX 82 68 86 69 86 / 10 10 10 10 10 DENTON, TX 86 70 93 71 89 / 10 10 10 10 20 MCKINNEY, TX 84 69 91 69 88 / 10 10 5 10 10 DALLAS, TX 88 72 93 72 90 / 10 10 5 10 10 TERRELL, TX 87 69 90 70 89 / 10 10 5 10 10 CORSICANA, TX 89 70 91 70 89 / 40 10 5 10 10 TEMPLE, TX 91 70 91 71 89 / 10 20 10 10 10 MINERAL WELLS, TX 94 70 96 70 93 / 10 20 10 20 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ /
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
718 AM CDT FRI MAY 17 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 350 AM CDT FRI MAY 17 2013 FOCUS IS ON TRENDING CURRENT SHOWERS/STORMS ACROSS IA/MN...AND CONVECTIVE PROBABILITIES LATER TODAY ALONG WARM FRONT. LATEST RADAR SHOWS COMPLEX OF SHOWERS/STORMS ACROSS NORTHERN IA/SOUTHERN MN...WHICH IS FEEDING OFF 850 MB LOW-LEVEL JET...INTERACTING WITH A WARM FRONTAL BOUNDARY THAT STRETCHES ACROSS NORTHERN IOWA. THESE STORMS ARE EFFICIENT HEAVY RAIN PRODUCERS...GIVEN SLOW EASTWARD PROGRESS AND PWATS 1.4 TO 1.6 INCHES...WHICH IS 150 TO 180 PERCENT ABOVE NORMAL. THESE STORMS ARE EXPECTED TO MOVE EASTWARD ACROSS SOUTHEAST MINNESOTA AND EXTREME NORTHEAST IOWA...AND PARTS OF WESTERN WISCONSIN THROUGH MID/LATE MORNING. SOME OF THE STRONGER CELLS COULD PRODUCE SMALL HAIL...BUT NOT EXPECTING ANYTHING TO REACH SEVERE LIMITS. THE BIGGER IMPACT WOULD BE LOCALIZED HEAVY RAINFALL...AND IN TOTAL...AMOUNTS BETWEEN 1 AND 2 INCHES ARE POSSIBLE. THE BIG QUESTION FOR TODAY IS WHERE THE WARM FRONT ENDS UP...AND IF ANOTHER ROUND OF SHOWERS/STORMS DEVELOPS ALONG IT THIS AFTERNOON. LATEST RAP HAS A DECENT HANDLE RIGHT NOW...SHOWING THAT THE WARM FRONT SETTLES ALONG THE IA/MN BORDER...AND INTO SOUTHWEST WISCONSIN THIS AFTERNOON. ONGOING CONVECTION SHOULD KEEP NORTHWARD PROGRESS OF THE BOUNDARY LIMITED SO RAP SOLUTION SEEMS REASONABLE. THE REMNANTS OF THIS MORNING/S STORMS WOULD LIFT TO THE EAST/NORTHEAST...BUT LEFTOVER OUTFLOW BOUNDARIES COMBINED WITH MODEST DAYTIME HEATING AND A PASSING UPPER LEVEL SHORTWAVE LOOKS TO BE SUFFICIENT FOR ADDITIONAL SHOWERS AND STORMS TO DEVELOP. THESE SHOWERS AGAIN WOULD HAVE THE POTENTIAL TO PRODUCE HEAVY RAIN. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 350 AM CDT FRI MAY 17 2013 ...SEVERE WEATHER EVENT POSSIBLE SUNDAY AND AGAIN ON MONDAY... SATURDAY FEATURES UPPER LEVEL RIDGING ACROSS THE CENTRAL PLAINS AS THE WEST COAST TROUGH CONTINUES TO MOVE EASTWARD. AT THE SURFACE...LOW PRESSURE DEVELOPS IN THE LEE OF THE ROCKIES AND PUSHES THE AFOREMENTIONED WARM FRONT WELL NORTH OF THE FORECAST AREA. THE ATMOSPHERE BECOMES CAPPED FOR THE DAY...WITH THE WARM NOSE LAYER EVIDENT IN THE 850 TO 750 MB LAYER. PLENTY OF ELEVATED CAPE NOTED ACROSS THE AREA...ANYWHERE FROM 2000 TO 3000 J/KG BY SATURDAY AFTERNOON. THE CAP REMAINS IN PLACE DURING THE DAY...BUT DOES WEAKEN SOME BY LATE AFTERNOON AND EVENING AS CIN VALUES DROP TO LESS THAN 50 J/KG...MAINLY ALONG AND NORTH OF I-90. THE LACK OF A STRONG FORCING MECHANISM SHOULD KEEP CONVECTIVE INITIATION PROBABILITIES LOW...AND THIS IS WELL AGREED AMONG THE VARIOUS DETERMINISTIC MODELS. THE ONLY EXCEPTION IS IN THE 17.00Z GFS WHERE A WEAK UPPER LEVEL SHORTWAVE TROUGHS RIDES THE RIDGE ACROSS NORTHERN WISCONSIN. THIS COULD PROVIDE ENOUGH UPPER LEVEL SUPPORT TO BREAK THE WEAKER CAP AND ALLOW SHOWERS/STORMS TO INITIATE. HAVE CONTINUED CHANCE POPS MAINLY NORTH OF I-90 TO HIGHLIGHT THIS IDEA. ANY STORM CAPABLE OF BREAKING THROUGH THE CAP AND BECOMING SURFACE BASED HAS THE POTENTIAL TO PRODUCE LARGE HAIL AND POSSIBLY DAMAGING WINDS GIVEN THE INSTABILITY AND 0-6 KM BULK SHEAR NEAR 30 KTS. OTHERWISE...WARM DAY ON TAP WITH HIGHS IN THE LOW TO MID 80S. FOCUS TURNS TO THE POTENTIAL SEVERE WEATHER EVENT FOR SUNDAY AS THE AFOREMENTIONED UPPER LEVEL TROUGH BECOMES INCREASINGLY NEGATIVE TILTED AND EJECTS INTO THE CENTRAL PLAINS BY 12Z SUNDAY. THE BASE OF THE TROUGH WILL LIKELY BE ACROSS OK/KS...BUT QUICKLY LIFTS NORTHEAST TOWARD WESTERN IOWA BY 00Z MONDAY. AT THE SURFACE...LOW PRESSURE LOOKS TO MOVE NORTHEASTWARD FROM NEBRASKA TO NEAR SIOUX FALLS SD...AND A WARM FRONT SHOULD BE DRAPED ACROSS SOUTHWEST MINNESOTA EAST/SOUTHEASTWARD INTO NORTHEAST IOWA. IT/S POSSIBLE THERE COULD BE SOME DECAYING CONVECTION SUNDAY MORNING ACROSS WESTERN IOWA...AND THIS COULD PLAY INTO HOW UNSTABLE THE ATMOSPHERE BECOMES LATER THAT DAY ACROSS THE REGION. IN ANY RATE...MUCAPE VALUES ARE EXPECTED TO RANGE 3000 TO 3500 J/KG AND 0-6 KM BULK SHEAR VALUES APPROACH 35 KTS WEST OF THE MISSISSIPPI RIVER SUNDAY AFTERNOON AND EVENING. THE MAJORITY OF THE SHEAR IS FOUND IN THE 0-3 KM LAYER WITH 25 KTS SEEN. EVEN MORE EXCITING ARE THE 0-1 KM SHEAR PARAMETERS...WHICH IS AT LEAST 20 KTS. FINALLY...THE AIRMASS ACROSS SOUTHEAST MINNESOTA AND NORTHERN IOWA SUNDAY LOOKS TO BE SOMEWHAT JUICY WITH DEWPOINTS IN THE 60S. HOW JUICY IS STILL A QUESTION GIVEN DETERMINISTIC MODELS POOR HANDLING OF DEWPOINTS LATELY. 17.00Z NAM/GFS PUT UPPER 60S TO EVEN NEAR 70F BY 21Z SUNDAY...WHICH SEEMS A BIT OVERDONE. ADJUSTING SOUNDINGS TO WHAT COULD BE A MORE REALISTIC VALUE /LOW TO MID 60S/ BASED ON THE MOIST BIAS STILL YIELDS CAPE VALUES IN THE 1500 TO 2500 J/KG RANGE. IN SHORT...ENVISION STORMS TO FIRE UP ACROSS CENTRAL IOWA INTO SOUTHERN MINNESOTA BY EARLY AFTERNOON SUNDAY...THEN QUICK MOVE EAST/NORTHEAST...LASTING INTO THE EVENING HOURS. THE HIGHER SEVERE CHANCES ARE WEST OF THE MISSISSIPPI RIVER...AS STORMS WOULD WEAKEN SOME MOVING INTO WISCONSIN BUT STILL COULD REMAIN SEVERE. ORGANIZED DISCRETE STRONG/SEVERE STORMS WOULD BE THE PRIMARY MODE...MAINLY SUPERCELLS...WITH A PREFERENCE TO THE RIGHT MOVERS GIVEN CLOCKWISE CURVATURE SEEN IN THE HODOGRAPHS. THE MAIN THREATS LOOK TO BE VERY LARGE HAIL AND DAMAGING WINDS BUT ALSO A FAVORABLE ENVIRONMENT FOR TORNADOES GIVEN 0-1 KM BULK SHEAR /AT LEAST 20 KTS/ AND EHI /1.0 TO 3.0/. WILL HIGHLIGHT INCREASED THREAT ACROSS THE MANY PUBLIC PRODUCTS /HWO...GRAPHICAST...NEWS STORY/. THOSE WITH PLANS SUNDAY AFTERNOON/EVENING WILL NEED TO KEEP A VERY CLOSE EYE TO THE FORECAST. ANOTHER ROUND OF STRONG/SEVERE STORMS IS POSSIBLE MONDAY EVENING AS THE WHOLE SYSTEM SLOWLY EDGES EASTWARD. ANOTHER FAVORABLE SEVERE WEATHER ENVIRONMENT WITH 0-6 KM MUCAPE PEGGED BETWEEN 2000 TO 3000 J/KG AND BULK SHEAR 30 TO 40 KTS. DEPENDING ON HOW MUCH EASTWARD PROGRESSION OF THE WEATHER SYSTEM OCCURS MONDAY...A GREATER PERCENTAGE OF THE FORECAST AREA COULD BE IN RISK FOR SEVERE WEATHER. AT THIS TIME...HIGHER THREAT AREA LOOKS TO BE ALONG AND SOUTH OF I-90. MODEL TIMING DIFFERENCES CREEP UP BY TUESDAY...MAINLY IN HOW QUICKLY THE UPPER LEVEL CLOSES OFF AND MOVES EAST OVER THE AREA. WIDE RANGE OF POSSIBILITIES ON WHEN THE LOW MOVES OVERHEAD...WITH THE 17.00Z GFS THE QUICKEST /TUESDAY/ AND THE ECMWF SLOWEST /WEDNESDAY/. FOR NOW...PERIODIC SHOWERS/STORMS TUESDAY AND WEDNESDAY LOOK GOOD. COOLER TEMPERATURES ALOFT AND THREAT OF SHOWERS SHOULD KEEP HIGHS ON THE COOLER SIDE WEDNESDAY AND THURSDAY...5 TO 7 DEGREES BELOW NORMALS. && .AVIATION...TODAY AND TONIGHT 715 AM CDT FRI MAY 17 2013 BROAD SHIELD OF RAIN MOVING THROUGH THE TAF SITES EARLY THIS MORNING. SOME MVFR CEILINGS AND VISIBILITY FOR A TIME...BUT EXPECTING THE RAIN TO LET UP AND CONDITIONS TO IMPROVE BY MID TO LATE MORNING. QUESTION THEN BECOMES ANY NEW CONVECTIVE DEVELOPMENT FOR THE AFTERNOON. SOME OF THE MESOSCALE MODELS ARE INDICATING SOME NEW DEVELOPMENT AS THE WARM FRONT PUSHES NORTHWARD AND THE UPPER TROUGH EDGES EVER CLOSER. AT THIS POINT IT IS LOOKING LIKE ANY REDEVELOPMENT WILL BE SPOTTY...AND MAY MISS THE TAF SITES ALTOGETHER. THUS DID NOT INCLUDE IN THE 12Z VERSION. WINDS SLACKEN TONIGHT...AND WITH A MOIST BOUNDARY LATER DUE TO RAIN TODAY AND INCREASING MOIST ADVECTION...EXPECT FOG COULD BECOME AN ISSUE. AT THIS POINT ADDED SOME MVFR FOG RESTRICTIONS TO THE TAFS AFTER 08Z. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. && $$ SHORT TERM...ZT LONG TERM...ZT AVIATION...MW
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
644 AM CDT FRI MAY 17 2013 UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE .SHORT TERM...TODAY...TONIGHT...AND SATURDAY ISSUED AT 346 AM CDT FRI MAY 17 2013 FORECAST CONCERNS THIS PERIOD ON PCPN CHANCES THROUGH THE PERIOD. WARM FRONT EXTENDS EAST OUT OF NE INTO NORTHERN IL. ONGOING PCPN OVER IA/MN BORDER...NOW EDGING INTO WESTERN WI. CLOUDS HAVE KEPT TEMPS UP OVERNIGHT OVER MUCH OF CWA...WITH ONLY THE FAR NORTH FALLING INTO THE UPPER 30S. EASTERLY WINDS OVER WI...STILL USHERING IN DRY AIR WITH DEW POINTS IN THE 30S. THIS HAS SLOWED ADVANCE OF PCPN...THOUGH HIGH BASED...THE RETURNS ARE INCREASING OVER THE STATE. HAVE CONTINUED TREND OF EVENING FORECASTER TO SHIFT PCPN SOUTH INTO CENTRAL AND EAST CENTRAL WI LATER THIS MORNING...THEN SHIFT NORTH TONIGHT AND SAT AS WARM FRONT LIFTS NORTH/RIDGE BUILDS IN. HAVE TRENDED TOWARDS MESO MODELS LIKE HRRR FOR DAY 1 PCPN TRENDS. PCPN FOCUS ASSOCIATED WITH INCREASING ISENTROPIC LIFT/FGEN FORCING WITH 850 BAROCLINIC ZONE OVER STATE. HAVE STAYED WITH JUST SHOWER MENTION THROUGH TODAY AS INSTABILITY MISSING OVER EASTERN WI...BRINGING IN SLIGHT CHANCE LATER TONIGHT AND SATURDAY AS LOW LEVEL MOISTURE INCREASES AND STEEPER MID LEVEL LAPSE RATES SHIFT EAST. TEMPS TODAY TO BE HELD BACK BY CLOUDS AND EAST FLOW THUS STAYED WITH UPPER 50S AND LOWER 60S THROUGHOUT CWA. MAX TEMPS BACK TO NORMAL OR ABOVE ON SAT...EXCEPT EAST WITH CONTINUED EASTERLY COMPONENT. .LONG TERM...SATURDAY NIGHT THROUGH THURSDAY ISSUED AT 346 AM CDT FRI MAY 17 2013 THE MAIN CONCERN DURING THE LONG TERM IS TIMING PRECIPITATION INTO THE AREA. A FRONTAL BOUNDARY IS FORECAST TO PUSH NORTHEAST THROUGH WISCONSIN EARLY NEXT WEEK. SURFACE FLOW WILL BE OFF LAKE MICHIGAN BETWEEN HIGH PRESSURE TO THE EAST AND THE FRONT...BUT PRECIPITATION WILL MOVE IN AS THE FRONT PASSES AND THE SURFACE LOW TO THE WEST GETS CLOSER TO WISCONSIN. HAVE A DRY FORECAST FOR SATURDAY NIGHT BUT WENT WITH CHANCE POPS FOR CENTRAL AND NORTH CENTRAL WISCONSIN SUNDAY. HAVE AT LEAST A CHANCE OF SHOWERS AND THUNDERSTORMS GOING THROUGH THE MIDDLE OF NEXT WEEK AS THE SURFACE LOW AND UPPER LEVEL CYCLONE PASS TO THE EAST OF THE AREA. TEMPERATURES SHOULD REMAIN ABOVE NORMAL THROUGH THE EARLY PART OF NEXT WEEK BEFORE A SURFACE RIDGE MOVES INTO THE REGION BRINGING COOLER THAN NORMAL TEMPERATURES FOR THE LATTER HALF OF THE WEEK. && .AVIATION...FOR 12Z TAF ISSUANCE ISSUED AT 637 AM CDT FRI MAY 17 2013 AREA OF PRECIPITATION HAS MOVE EAST OUT OF IOWA INTO CENTRAL WI AT THIS TIME. SOME QUESTION ON HOW FAR NORTH PCPN WILL GET THIS MORNING GIVEN DRY AIR LEFT OVER FROM DEPARTING HIGH PRESSURE. FORECAST TREND IS FOR THIS AREA TO AFFECT SOUTHERN TAF SITES WITH MORE SHOWER ACTIVITY FORMING WEST AND LIFTING NORTH AS WARM FRONT OVER THE PLAINS MOVES NORTH. BEST INSTABILITY TO SAY WELL SOUTH OF AREA SO WILL NOT MENTION THUNDER. DRY LOW LEVEL FLOW EXPECTED TO KEEP CIGS IN VFR CAT OR HIGH MVFR IS SOMW SHOWERS. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....TE LONG TERM......MG AVIATION.......TE
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
335 PM PDT FRI MAY 17 2013 .SHORT TERM DISCUSSION... UPPER LEVEL TROUGH IS MOVING EAST INTO THE GREAT BASIN THIS AFTERNOON. CONVECTION HAS NOT MATERIALIZED THUS FAR THIS AFTERNOON MUCH AS THE HRRR HAS PREDICTED. THE MAIN SUPPRESSOR SEEMS TO BE WARMING ABOVE 8000 FEET WHICH HAS CAPPED THE ATMOSPHERE. DELTA BREEZE HAS DEVELOPED WITH WINDS GUSTING TO 30 MPH OVER THE DELTA. TROUGH WILL CONTINUE EAST TONIGHT WITH DRIER AIR FILTERING INTO NORCAL PROVIDING CLEAR SKIES. UPPER RIDGE WILL BUILD INTO NORCAL TOMORROW WITH A DRY NORTHWEST FLOW DEVELOPING. TEMPERATURES WILL WARM INTO THE LOW TO MID 80`S FOR VALLEYS. WEAK DISTURBANCE PASSING THROUGH OREGON AND WASHINGTON WILL BRUSH THE NORTHERN MOUNTAINS LATE IN THE AFTERNOON WITH SOME INCREASED CLOUD COVER. ALSO ADDED SLIGHT SHOWER CHANCES OVER THE NRN SIERRA NEAR LASSEN. UPPER TROUGH WILL DEEPEN OVER THE ROCKIES ON SUNDAY WITH GUSTY NORTH WINDS DEVELOPING ON THE BACKSIDE OF THIS FEATURE OVER THE SAC VALLEY. GUSTS UP TO 35 MPH WILL BE POSSIBLE AND WIND ADVISORY MAY BE NEEDED IF WIND FORECAST CONFIDENCE INCREASES. TEMPERATURES WILL WARM INTO THE MID-UPPER 80`S FOR VALLEY LOCATIONS. RIDGE WILL STRENGTHEN ON MONDAY WITH TEMPS WARMING INTO THE LOW 90`S AT MOST VALLEY LOCATIONS. .EXTENDED DISCUSSION (TUESDAY THROUGH FRIDAY) A CLOSED UPPER-LEVEL LOW WITH REACH THE PACIFIC NW BY THE MIDDLE OF NEXT WEEK. BASED ON PREDICTABILITY AND ENSEMBLE PLOTS...MODELS ARE SHOWING A HIGH DEGREE OF CERTAINTY IN THIS FEATURE. THE MAIN EFFECT FOR OUR AREA WILL BE COOLER TEMPERATURES...WITH PERHAPS SOME SHOWERS FROM SHASTA COUNTY NORTHWARD. FIRST CHANCE WOULD BE TUESDAY NIGHT AS THE INITIAL WAVE AT THE BASE OF THE LOW BRUSHES OUR NORTHERN REACHES. SLIGHT CHANCES LINGER THROUGH THURSDAY...BEFORE A SECONDARY WAVE TAKES AIM AT NORCAL. THIS IS WHERE MODELS DIVERGE. THE 12Z ECMWF CHANGED SIGNIFICANTLY FROM THE 00Z SOLUTION...NOW TRENDING TOWARDS A PROGRESSIVE LOW AFFECTING OUR AREA NORTH OF I80 THURSDAY NIGHT THEN QUICKLY LIFTING EASTWARD (THE 00Z HAD AN SLOWER CLOSED LOW CENTERED RIGHT OVER SAC BY FRIDAY). THE GFS MEANWHILE IS LESS PROGRESSIVE...AND DIGS A DEEPER TROUGH ALONG THE WEST COAST FROM FRIDAY INTO THE WEEKEND. OVERALL MESSAGE IS COOLER TEMPERATURES WITH A CHANCE OF RAIN SHOWERS OVER THE MOUNTAINS. -DVC && .AVIATION... VFR CONDITIONS CONTINUE OVER INTERIOR NORCAL TAF SITES NEXT 24 HOURS. A WEAK LOW PRESSURE SYSTEM WILL BRUSH TO THE NORTH OF THE AREA TOMORROW AFTERNOON...WITH THE ONLY EFFECT BEING A FEW MID- LEVEL CLOUDS FROM AROUND KRBL NORTH. GENERALLY LIGHT WINDS EXPECTED THROUGH THE PERIOD. -DVC && .STO WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1049 AM MDT FRI MAY 17 2013 .UPDATE... && .SHORT TERM...DRY AND VERY WARM AIR HAS SPREAD OVER THE FORECAST AREA TODAY IN ADVANCE OF AN ABNORMALLY STRONG UPPER LEVEL TROUGH CURRENTLY MOVING VERY SLOWLY EASTWARD OVER THE GREAT BASIN. HOWEVER...LATER THIS AFTERNOON AND EVENING...A WARM AND MOIST SOUTHEAST WIND ON THE PLAINS MAY CREATE CONDITIONS SUFFICIENTLY UNSTABLE TO PRODUCE A FEW STRONG AND POSSIBLY SEVERE THUNDERSTORMS IN THE NORTHEAST CORNER OF THE STATE. HAIL AROUND ONE INCH IN DIAMETER AND WIND GUSTS TO AROUND 60 MPH WILL BE THE PRINCIPLE THREAT. RAINFALL FROM THESE RELATIVELY FAST MOVING STORMS IS NOT EXPECTED TO RESULT IN FLOODING. THIS LIMITED THUNDERSTORM ACTIVITY SHOULD EXIT THE STATE BY AROUND MID- EVENING. OTHERWISE...TEMPERATURES ALREADY RUNNING QUITE WARM. TEMPERATURE READINGS AS OF 16Z WERE RUNNING 3 TO 9 DEG F ABOVE THOSE OBSERVED 24 HOURS AGO. AT THIS PACE UNDER GENERALLY CLEAR SKIES...COULD SEE MAX TEMPERATURES IN MANY AREAS NEARING IF NOT EXCEEDING RECORDS FOR THIS DATE. IT`S ALREADY 83 AT DIA. RECORD HIGH FOR DENVER IS 91 DEGS. COULD COME REAL CLOSE. .AVIATION...VFR CONDITIONS ANTICIPATED NEXT 24 HOURS. WEST- SOUTHWEST WINDS OF 7-14 KTS AT DENVER AREA AIRPORTS THROUGH MID- AFTERNOON. THEN WEST-NORTHWEST WINDS AT SIMILAR SPEEDS THROUGH EARLY THIS EVENING. THEN OVERNIGHT LOOK FOR A RETURN TO TYPICAL DRAINAGE WINDS OF 5-11 KTS. && .HYDROLOGY...ABNORMALLY WARM TEMPERATURES TODAY WILL ACCELERATE SNOWMELT IN THE HIGH COUNTRY. THE RESULTING INCREASED RUNOFF MAY CAUSE MINOR RISES ON SMALL CREEKS AND STREAMS. HOWEVER...WATER LEVELS SHOULD REMAIN WELL BELOW FLOOD STAGE. && .PREV DISCUSSION... /ISSUED 407 AM MDT FRI MAY 17 2013/ SHORT TERM...DRIER AIR IN INCREASING SOUTHWEST FLOW ALOFT WILL SPREAD ACROSS THE AREA TODAY. AT THE SFC LOW PRESSURE WILL EXTEND FM SERN WY INTO ERN CO WITH INCREASING SLY WINDS BY AFTN OVER THE NERN PLAINS. LATE AFTN CAPES WILL RANGE FM 1500-2000 J/KG OVER THE FAR NERN CORNER EAST OF A STERLING TO LIMON LINE. SOUNDINGS SHOW CAP ERODING AFTER 22Z SO COULD SEE SOME ISOLD STORMS THRU 03Z. WITH FAVORABLE SHEAR PROFILE IF A FEW STORMS DO DVLP THEY COULD BECOME SVR. OTHERWISE IT WILL BE DRY OVER THE REST OF THE AREA WITH AFTN HIGHS WELL ABV NORMAL. CURRENT 850-700 MB TEMPS WOULD SUPPORT HIGHS IN THE UPPER 80S TO LOWER 90S ACROSS MOST OF NERN CO. RECORD HIGH AT DENVER IS 91 SO IT COULD GET CLOSE THIS AFTN. LONG TERM...NO CHANGES TO THE FORECAST THINKING THROUGH THE WEEKEND AND INTO NEXT WEEK. MODELS CONTINUE TO SHOW A SLOWLY EVOLVING UPPER AIR PATTERN THAT FEATURES A BROAD UPPER TROUGH SETTLING OVER THE STATE SATURDAY AFTERNOON AND THEN TAKING TIL TUESDAY TO MOVE ON TO THE NORTHERN PLAINS. WHILE THE UPPER TROUGH LAGS OVER THE STATE...COOLER AND SOMEWHAT UNSETTLED WEATHER WILL PREVAIL WITH PERIODS OF SHOWERS AND POSSIBLY SOME EMBEDDED THUNDERSTORMS ACROSS THE FORECAST AREA. DYNAMIC FORCING WITH THE UPPER TROUGH WILL NOT BE ALL THAT STRONG...SO PRECIPITATION AMOUNTS LOOK LIKE THEY WILL ONLY BE LIGHT TO MODERATE. THE COOLEST DAY OF THE SET APPEARS TO BE MONDAY...WITH A GRADUAL WARMING TREND EXPECTED THROUGH THE REMAINDER OF NEXT WEEK. THE COOLER THAN NORMAL TEMPERATURES ALONG WITH PERIODS OF LIGHT RAIN SHOULD HELP THE SPRING VEGETATION STAY GREEN FOR A LITTLE LONGER. AVIATION...VFR THRU TONIGHT. SLY WIND EARLY THIS MORNING MAY BECOME MORE SWLY BY 14Z. BY 18Z THE RAP HAS THE WINDS STAYING SSW WHILE THE NAM IS MORE WLY. BY 21Z BOTH MODELS SHOW THE WNDS SSW. FOR NOW WILL KEEP THEM SSW THRU THE AFTN. FOR TONIGHT WILL KEEP THE WINDS DRAINAGE OVERNIGHT. HYDROLOGY...NO ISSUES. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...BAKER/RPK LONG TERM....DANKERS AVIATION...BAKER/RPK
AREA FORECAST DISCUSSION
NWS MIAMI FL
229 PM EDT FRI MAY 17 2013 .DISCUSSION... A WEAK AREA OF LOW PRESSURE REMAINS OVER SOUTH FLORIDA EARLY THIS AFTERNOON...AND THIS FEATURE WILL DRIFT TO THE WEST AND PUSH OUT INTO THE GULF OF MEXICO LATER TONIGHT. THIS WILL BRING SOME SUBSIDENCE TO THE WESTERN HALF OF THE REGION...SO REMOVED THE POPS FOR THE NAPLES AREA THIS AFTERNOON. SHOWERS THAT HAVE FORMED HAVE HAD HIGH BASES...WHICH INDICATES THERE IS STILL DRY AIR IN THE LOW LEVELS. WATER VAPOR IMAGERY INDICATES DRIER MID LEVEL AIR IS MOVING IN FROM THE NORTHWEST...AND THE DRIER AIR IN THE LOW AND MID LEVELS SHOULD PREVENT MANY...IF ANY THUNDERSTORMS THIS AFTERNOON. THE GFS HAS BACKED OFF ON ANY SHOWERS THIS AFTERNOON...EXCEPT FOR PALM BEACH COUNTY WHERE THEY WERE OCCURRING. THE HRRR STILL SHOWED ISOLATED TO SCATTERED SHOWERS ALONG THE EAST COAST SEA BREEZE AFTER 20-21Z. SO LEFT THE ISOLATED TO SCATTERED SHOWERS AND SLIGHT CHANCE OF THUNDER WORDING. ANY SHOWERS OR STORMS THAT DEVELOP MAY CONTINUE INTO THE EARLY EVENING BEFORE DISSIPATING. AN UPPER RIDGE STRETCHING FROM TEXAS THROUGH THE NORTHERN PLAINS WILL SLOWLY SHIFT EAST THROUGH THE WEEKEND. A WEAK SHORTWAVE WILL DIVE SOUTHEAST SATURDAY AFTERNOON ACROSS FLORIDA IN THE NORTHWESTERLY FLOW ALOFT. TEMPERATURES ALOFT ARE EXPECTED TO COOL TO -10 TO -11C WITH 25-30 KNOTS OF 0-6KM BULK SHEAR. LAPSE RATES ALOFT ARE NOT THAT IMPRESSIVE AND THERE IS STILL DRY AIR IN THE LOW/MID LEVELS. HOWEVER...A COUPLE STRONG STORMS CANNOT BE RULED OUT ALONG THE SEA BREEZE BOUNDARIES...MAINLY ACROSS THE INTERIOR. STORM MOTION WILL BE DEPENDENT ON THE SEA BREEZE AND OUTFLOW BOUNDARIES. HIGHS ON SATURDAY WILL BE NEAR NORMAL IN THE MID 80S TO LOWER 90S. TEMPS WILL WARM ALOFT A BIT ON SUNDAY...AND SLIGHTLY DRIER AIR WILL MOVE IN FROM THE EAST. SO THE EAST COAST SHOULD REMAIN MAINLY DRY EXCEPT FOR POSSIBLY A FEW MORNING SHOWERS...WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE INTERIOR AND GULF COAST. AN UPPER TROUGH WILL PUSH INTO THE INTERMOUNTAIN WEST ON SUNDAY AND INTO THE NORTHERN PLAINS ON MONDAY...AND HIGH PRESSURE WILL SHIFT TO THE EAST. THE LOW LEVEL FLOW WILL BEGIN TO SHIFT TO THE SOUTHEAST...WITH SLIGHTLY DEEPER MOISTURE BEGINNING TO MOVE INTO THE REGION. THE HIGHEST POPS WILL REMAIN OVER THE INTERIOR AND GULF COAST. A WEAK UPPER TROUGH/LOW WILL PUSH SOUTHEAST INTO THE WESTERN ATLANTIC BY SUNDAY AS IT GETS TRAPPED BENEATH A RIDGE OF HIGH PRESSURE. THIS FEATURE IS EXPECTED TO THEN RETROGRADE SLOWLY TO THE WEST SOUTHWEST THROUGH THE MIDDLE OF THE WEEK. IF THIS TROUGH MOVES AS THE GFS INDICATES...DEEP SOUTHEASTERLY FLOW WOULD PREVAIL ON TUESDAY...WITH TROPICAL MOISTURE MOVING INTO SOUTH FLORIDA. THE ECMWF IS SLIGHTLY SLOWER AND PUSHES THE WEAK UPPER TROUGH/LOW OVER DEEP SOUTH FLORIDA OR THE WESTERN GULF ON WEDNESDAY...DELAYING THE DEEP MOISTURE UNTIL THAT TIME. EITHER WAY...IT APPEARS THAT DEEP MOISTURE WILL MOVE OVER SOUTH FLORIDA BY THE MIDDLE OF THE WEEK AND REMAIN THROUGH THE END OF THE FORECAST PERIOD. && .AVIATION... WEAK LOW PRESSURE NORTH OF KPBI FOCUSED SHOWERS THIS MORNING IN THAT AREA, BUT WITH THE LOW MOVING TO THE NORTH THIS AFTERNOON, EXPECT SHOWERS/ISOLATED TSTMS TO BE CONCENTRATED OVER THE INTERIOR WITH VFR CONDITIONS AND VCSH FOR THE EAST COAST SITES. KAPF SHOULD SEE NO MORE THAN A FEW CLOUDS WITH GULF SEA BREEZE THIS AFTERNOON. QUIET NIGHT EXPECTED WITH ISOLATED SHOWERS AT WORST ALONG THE E COAST AND PATCHY INLAND FOG. SE FLOW ON SATURDAY CONTINUING TO BRING IN A FEW SHOWERS MAINLY E COAST WITH VFR PREVAILING. && .MARINE... THE WINDS WILL BE EASTERLY AROUND 10 KNOTS TONIGHT INTO THIS WEEKEND. THIS WILL KEEP THE ATLANTIC AND GULF WATER SEAS AROUND 2 FEET THROUGH THE WEEKEND. SO BOATING CONDITIONS SHOULD BE GOOD THROUGH THIS WEEKEND OUTSIDE OF ANY SHOWERS AND THUNDERSTORMS THAT DO DEVELOP OVER SOUTH FLORIDA WATERS. && .FIRE WEATHER... THE RELATIVE HUMIDITY OVER SOUTH FLORIDA WILL REMAIN ABOVE THE 35 PERCENT CRITICAL VALUE THROUGH THIS WEEKEND. DEEP MOISTURE WILL RETURN TO THE REGION EARLY TO THE MIDDLE PART OF NEXT WEEK. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 74 85 75 85 / 20 30 20 20 FORT LAUDERDALE 76 86 77 86 / 20 20 20 20 MIAMI 75 87 76 86 / 20 20 20 20 NAPLES 71 88 71 89 / 10 20 20 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...84/AK AVIATION/RADAR...59/RM
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1230 PM CDT FRI MAY 17 2013 .UPDATE... ISSUED AT 649 AM CDT FRI MAY 17 2013 THE NOCTURNAL MCS WILL CONTINUE MOVING EAST FROM MN INTO WI THIS MORNING BEFORE SLOWLY DISSIPATING. BOUNDARIES LEFT OVER FROM THAT CONVECTION WILL BE THE PRIMARY FOCUS FOR DIURNAL CONVECTION TODAY. MCS AND LIFT TOOLS PER RAP TRENDS SHOW THE THETA E GRADIENT AND ASSOCIATED CONVERGENCE/LIFT IS JUST NORTH OF THE AREA. THUS DRY CONDITIONS ARE EXPECTED THROUGH MID DAY ACROSS THE AREA. THE CURRENT FCST HAS CONVECTION DEVELOPING IN THE AFTERNOON BUT IT IS DEPENDENT ON WHEN CONVECTIVE TEMPERATURE IS ACHIEVED. IF THE RAP IS CORRECT WE WOULD REMAIN BELOW CONVECTIVE TEMPERATURE. HOWEVER... THE RAP TRENDS DO SHOW AREAS OF CONVERGENCE DEVELOPING DURING THE AFTERNOON ALONG WITH WEAK THETA E GRADIENTS. SO...ISOLATED TO SCATTERED CONVECTION IS EXPECTED THIS AFTERNOON WITH THE NORTH THIRD MORE FAVORED DUE TO THE PROXIMITY OF THE FRONTAL BOUNDARY. STORMS WILL BE SLOW MOVING DUE TO THE UPPER RIDGE SO ANY THUNDERSTORM THAT DEVELOPS WILL HAVE THE POTENTIAL TO PRODUCE VERY LOCALIZED HEAVY RAINFALL OF AN INCH OR MORE. ..08.. && .SYNOPSIS... ISSUED AT 229 AM CDT FRI MAY 17 2013 06Z SFC ANALYSIS HAS A WEAK LOW IN WESTERN IOWA JUST EAST OF KSUX AND ANOTHER IN SOUTHERN SOUTH DAKOTA. AN EAST/WEST FRONTAL BOUNDARY RAN FROM NORTHERN OHIO...THROUGH CENTRAL INDIANA...AND TO THE LOW NEAR KSUX. FLOW OFF LAKE MICHIGAN HAD DEW POINTS RANGING FROM THE UPPER 30S NORTH OF THE FRONT TO 50S AND LOW 60S SOUTH OF THE FRONT. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 229 AM CDT FRI MAY 17 2013 THE CURRENT CONVECTION ON RADAR IS OCCURRING ALONG A THETA E GRADIENT AND MOISTURE/TEMPERATURE GRADIENTS FROM THE 850MB FRONT. MOST OF THE AREA WILL REMAIN DRY THROUGH SUNRISE EXCEPT FOR VERY ISOLATED CONVECTION IN THE HWY 20 CORRIDOR. THE MORNING HOURS ARE EXPECTED TO BE MAINLY DRY WITH PASSING CLOUDS AS THE THETA E GRADIENT MOVES NORTH INTO WISCONSIN. DIFFERENTIAL HEATING COMBINED WITH AN APPROACHING VORT MAX SHOULD RESULT IN ISOLATED TO SCATTERED CONVECTION DEVELOPING BY LATE MORNING IN THE EASTERN CWFA. DURING THE AFTERNOON HOURS...ISOLATED TO SCATTERED CONVECTION WILL EXPAND TO MOST OF THE CWFA AS CONVECTIVE TEMPERATURES ARE REACHED. THE PROXIMITY OF THE UPPER RIDGE MEANS THAT STEERING CURRENTS FOR THE CONVECTION ARE VERY WEAK. THUS THOSE AREAS THAT DO SEE RAIN THIS AFTERNOON WILL HAVE THE POTENTIAL TO SEE LOCALLY HEAVY RAINFALL. CONVECTION WILL SLOWLY DIMINISH WITH SUNSET BUT ISOLATED TO SCATTERED CONVECTION IS EXPECTED TO CONTINUE INTO THE EVENING OVER ROUGHLY THE NORTHEAST HALF OF THE CWFA. BY LATE EVENING MAINLY DRY CONDITIONS ARE EXPECTED WITH LITTLE IF ANY CONVECTION AFTER MIDNIGHT. 08 .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 229 AM CDT FRI MAY 17 2013 MAIN CHALLENGE IS THE PROBABLE SEVERE WEATHER RISKS SUN/MON. OVERVIEW...INITIALIZATION AND VERIFICATION FAIR WITH ALL SOLUTIONS HAVING DIFFICULTY WITH ONGOING CENTRAL IOWA MCS EVENT. COUPLED WITH BL DEWPOINT ISSUES SUGGEST AGAIN USE OF CONCEPTUAL PRECIPITATION EVOLUTION TOOLS DERIVED FROM THE FORCING OF A BLEND OF GEM-NH /HI-RES ECMWF/GFS. THIS SUPPORTS A DECENT RISK OF SEVERE STORMS SUN/MON WITH PHASING AND CONVECTIVE ISSUES THAT SHOULD BETTER CLARIFIED IN THE NEXT 24 HOURS. HIGHER END SEVERE STORM EVENTS FOR REGION APPEAR MARGINAL ATTM FOR THE AREA WITH LOW/MODERATE SEVERE EVENTS SUGGESTED ATTM. SATURDAY...MINOR CHANGES WITH AREA LIKELY PARTLY SUNNY AND DRY AHEAD OF SEASONABLY STRONG UPPER LEVEL SYSTEM MOVING INTO WEST CENTRAL PLAINS. WARM AND A BIT HUMID WITH HIGHS IN THE LOWER 80S AND LOWS MOSTLY IN THE LOWER 60S WITH DEWPOINTS 60-64F. SOME PATCHY FOG POSSIBLE WITH ANY CLEARING FOR LATER SHIFTS TO CONSIDER. SUNDAY AND MONDAY. GOOD SHEAR AND AT LEAST MODERATE INSTABILITY SUPPORT ONE OR MORE CONVECTIVE EVENTS SUGGESTED WITH ENVIRONMENT MOSTLY FAVORABLE FOR CONVECTIVE BOWING SEGMENTS ATTM. SEVERE WEATHER AREAL TOOL AND BLEP/HELP ALGORITHMS SUGGEST WITH T/TDS AOA 83/63 OF 60-70 MPH STRAIGHT LINE WINDS AND SOME HAIL THAT COULD APPROACH 1.75 INCHES WITH WBZ OF ~11K AGL AND SBCAPE OF 2000-3000 J/KG. IF ANY WAVE FORMS IN LATE PM/EVENING THERE IS A RISK OF ISOLATED TORNADOES BUT THIS APPEARS MARGINAL DUE TO CURRENT JET STRUCTURE AND TIMING. HIGHS SUGGESTED BASED ON PARTLY SUNNY SKIES SHOULD BE IN THE LOWER/MIDDLE 80S AND MINS MOSTLY IN THE MIDDLE 60S. PW/S OF 1.25+ INCHES DO SUPPORT LOCALLY HEAVY RAINFALL WITH ANY TRAINING OF STORMS. POPS IN THE LIKELY CATEGORY TO THE MID/HIGH CHANCE WITH TIMING MAIN ISSUE. LOCAL FORCING AND HEAVY RAIN TECHNIQUES DO SUPPORT MOST AREAS TO PICK UP AN INCH OR MORE OF RAIN WITH PASSAGE OF UPPER LEVEL SYSTEM OVER NEXT 96+ HOURS. TUESDAY...A CHALLENGE WITH WAVE BASED ON CONVECTION FIRING OVER SOUTHERN PLAINS THE KEY ISSUE. JET STRUCTURE SUPPORTS DECENT RAIN EVENT WITH LOTS OF CLOUDS AND THIS WOULD IMPACT HIGH TEMPERATURES FOR LATER SHIFTS THAT MAY NEED LOWERING OVER CENTRAL AND SE SECTIONS. POPS MAY NEED RAISING AS WELL BY 10-20 PERCENT WITH MODERATE TO LOW END HEAVY AMOUNTS SUGGESTED. CONVECTIVE FEEDBACK QUESTION SHOULD BE CLARIFIED MORE IN THE NEXT 24-36 HOURS. TUESDAY NIGHT...UPPER LOW MOVES INTO AREA WITH CHANCE OF LOW TOP CONVECTION OF SHOWERS AND BRIEF THUNDERSTORMS. MINS OF 55-60F WITH TEMPS POSSIBLY A BIT TOO COOL IN FAR SE SECTIONS WITH CLOUDS. WEDNESDAY AND THURSDAY...UPPER LOW TO SLIDE SLOWLY EAST WITH CHANCE SHOWERS AND POSSIBLY ISOLATED THUNDER WITH PARTLY TO MOSTLY CLOUDY SKIES. HIGH TEMPERATURES 67-77F SUGGESTED. LOWS IN THE 50S WED AM AND MID/UPPER 40S TO LOWER 50S SE SECTIONS THU AM. SEASONABLY STRONG CANADIAN HIGH PRESSURE TO THEN DOMINATE AND KEEP AREA COOL WITH LOW DEWPOINTS AND BELOW NORMAL INTO NEXT WEEKEND. NICHOLS && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1214 PM CDT FRI MAY 17 2013 SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS AFTERNOON... PRODUCING ISOLATED HEAVY RAINFALL AND LOCAL MVFR CIGS AND VSBYS. OUTSIDE OF THUNDERSTORMS...VFR CONDITIONS WILL CONTINUE THROUGH THE EVENING. OVERNIGHT AREAS OF FOG AND IFR CIGS ARE EXPECTED TO SETTLE ACROSS THE REGION...IMPROVING ONCE AGAIN TO VFR AFTER 14Z/18. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ UPDATE...08 SYNOPSIS...08 SHORT TERM...08 LONG TERM...NICHOLS AVIATION...DMD
AREA FORECAST DISCUSSION
NWS GAYLORD MI
125 PM EDT FRI MAY 17 2013 .SYNOPSIS... ISSUED AT 352 AM EDT FRI MAY 17 2013 HIGH PRESSURE WILL REMAIN IN CONTROL OF NORTHERN MICHIGANS WEATHER THROUGH TODAY...RESULTING IN DRY WEATHER UNDER PARTLY SUNNY SKIES AND SEASONABLE TEMPERATURES. WARM AND MOIST AIR PRESSING INTO THE MIDWEST AND GREAT LAKES WILL BRING A CHANCE FOR SHOWERS TO THE NORTH WOODS OVER THE WEEKEND...MAINLY ON SATURDAY. && .UPDATE... ISSUED AT 116 PM EDT FRI MAY 17 2013 WELL...HIGH RES RUNS HAVE SHOWN THEIR USEFULNESS...PEGGING DECAYING MCS REMNANTS OVERSPREADING AREAS ALONG AND SOUTH OF M-72 THIS AFTERNOON. RADAR AND SURFACE TRENDS NO DOUBT BEAR THIS OUT...WITH LIGHT RAIN REPORTED AT FKS...MBL...AND CAD WITHIN THE LAST HOUR. THIS LIGHT RAIN SHOULD CONTINUE TO SPREAD EAST...AND HAVE SIGNIFICANTLY ADJUSTED FORECAST TO SHOW THESE TRENDS. COOL EAST FLOW AND EXTENSIVE CLOUDS ACROSS NORTHERN LOWER ALSO PLAYING HAVOC WITH TEMPERATURE TRENDS. READINGS ALREADY WELL SHORT OF WHAT WAS EARLIER ANTICIPATED. HAVE ADJUSTED THESE DOWNWARD...ALTHOUGH WHERE RAIN PERSISTS...MAY NOT YET BE COOL ENOUGH. UPDATE ISSUED AT 936 AM EDT FRI MAY 17 2013 INCREASINGLY CHALLENGING FORECAST DEVELOPING FOR TODAY. UPSTREAM REMNANT MCS ON LEADING EDGE OF THETA-E ADVECTION/NOSE OF LOW LEVEL JET CONTINUES TO DRIVE EAST ACROSS SOUTHERN WISCONSIN...WITH SOME LEADING EDGE RETURNS SPILLING INTO SOUTHWEST SECTIONS OF OUR AREA (EVEN SOME EVIDENCE OF MID LEVEL FGEN HELPING MAINTAIN/EXPAND THESE LEADING EDGE SHOWERS). LOW LEVELS REMAIN DRY...AND JUST HAD FIRST REPORTS OF RAIN REACHING THE SURFACE AT CADILLAC. HAVE ADJUSTED FORECAST A TOUCH MORE PESSIMISTICALLY SOUTH OF TRAVERSE CITY...ALTHOUGH TRENDS SUGGEST PERHAPS NOT PESSIMISTICALLY ENOUGH. LATEST HIGH RES HRRR SOMEWHAT DISCONCERTING...DRIVING DECAYING MCS ACROSS THE SOUTH HALF OF THE AREA THIS AFTERNOON...PRODUCING RATHER WIDESPREAD LIGHT SHOWERS. PERUSAL OF OTHER GUIDANCE AND MODEL DERIVED SOUNDINGS SUGGEST OTHERWISE...WITH DEEP LOW LEVEL DRY LAYER AND LOSS OF DYNAMICS ESSENTIALLY FULLY DECAYING THIS ACTIVITY BEFORE IT REACHES OUR AREA. THAT SAID...RADAR RETURNS MORE THAN OMINOUS...AND DEFINITE FUTURE CHANGES MORE THAN EXPECTED. MORE CLOUDS/RAIN WOULD ALSO MEAN SIGNIFICANTLY COOLER TEMPERATURES ACROSS THE SOUTH. WILL CONTINUE TO MONITOR. UPDATE ISSUED AT 606 AM EDT FRI MAY 17 2013 FORECAST APPEARS ON TRACK FOR THE MOMENT. SUBSTANTIAL HIGH CLOUDS FROM UPSTREAM CONVECTION HAVE OVERSPREAD MUCH OF THE CWA... ESPECIALLY NRN LOWER MICHIGAN. SATELLITE TRENDS REVEAL ABUNDANT HIGHER CLOUD COVER UPSTREAM THAT WILL CONTINUE TO STREAM THROUGH THE REGION TODAY. THUS PARTLY SUNNY TO OCCASIONALLY MOSTLY CLOUDY SKIES SHOULD WORK OUT. OTHERWISE...QUITE A FEW LOCATIONS ARE IN THE UPPER 30S WITH A FEW SPOTS COLDER (PLN IS 32F). WARMEST LOCATIONS ARE IN THE SW COUNTIES (TVC/FKS/MBL...ETC). CAN PROBABLY SAFELY TRIM THOSE COUNTIES OUT OF THE FREEZE ADVISORY EARLY. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 352 AM EDT FRI MAY 17 2013 OVERVIEW: FAIRLY PROGRESSIVE FLOW PATTERN ACROSS THE CONUS CURRENTLY BUT STARTING TO BECOME MORE AMPLIFIED AS TROUGHINESS DEEPENS ALONG THE WEST COAST...AND DOWNSTREAM RIDGING BUILDS THROUGH THE PLAINS AND INTO THE GREAT LAKES. RIDGING GRADUALLY BUILDS INTO THE GREAT LAKES HEADING THROUGH THE WEEKEND SIGNALING WARMER DAYS AHEAD. MEANWHILE...HIGH PRESSURE HAS NUDGED IT/S WAY DOWN OUT OF ONTARIO AND INTO THE WESTERN GREAT LAKES. ONGOING MCS ACTIVITY TO OUR SOUTHWEST ACROSS IOWA...BUT WILL STAY WELL AWAY FROM US AS MOISTURE/INSTABILITY REMAINS DISPLACED WELL OFF TO OUR WEST AND SOUTH. TODAY...HIGH PRESSURE AND ANTECEDENT DRY AIRMASS WILL CONTINUE TO DOMINATE THE REGION WITH NO PRECIP ANTICIPATED. HOWEVER...THERE IS QUITE A BIT OF MID AND HIGH CLOUD COVER UPSTREAM FROM ONGOING CONVECTION AS WELL AS INCREASING WARM ADVECTION ACROSS THE PLAINS. THUS...WILL SEE VARIOUS ROUNDS OF MID AND HIGH CLOUD SLIDING THROUGH THE REGION...LEADING TO PARTLY CLOUDY TO OCCASIONALLY MOSTLY CLOUDY SKIES. TEMPERATURES...A LITTLE WARMER AS COMPARED TO THURSDAY WITH HIGHS RANGING FROM THE MID 60S TO LOWER 70S. FIRE WEATHER CONCERNS...DRY ANTECEDENT CONDITIONS PERSIST AND EXPECT INLAND SFC DEWPOINTS WILL DIP INTO THE LOWER 30S DURING THE AFTERNOON LIKE THURSDAY WITH MINIMUM RH VALUES GOING BELOW 25 PERCENT. HOWEVER...TEMPS WILL LARGELY REMAIN BELOW 75 FOR MOST AREAS AND WINDS WILL BE FAIRLY LIGHT (UNDER 10 MPH). YES IT WILL BE DRY BUT WITHOUT DECENT WIND...WILL NOT HAVE ELEVATED FIRE DANGER MENTIONED IN THE HWO FOR TODAY. TONIGHT...WARM AND MOIST AIR (HIGH THETA-E) BUILDS THROUGH THE PLAINS AND THE UPPER MIDWEST THROUGH THE COURSE OF THE NIGHT WITH THE STRONGEST SURGE/FORCING OCCURRING ACROSS THE NRN PLAINS AND UPPER MIDWEST WHERE ONE OR MORE CONVECTIVE SYSTEMS WILL LIKELY BE ONGOING OR DEVELOP. HERE AT HOME...NOT SO IMPRESSED. NW-SE ORIENTED THETA-E GRADIENT WILL BE INCHING UP THROUGH STATE THROUGH THE COURSE OF THE NIGHT. BUT AGAIN...MUCH STRONGER LOW LEVEL FLOW AND RESULTING FORCING (MOIST CONVERGENCE) WILL REMAIN WELL WEST-NORTHWEST OF THE CWA WHERE MOST CONVECTIVE ACTIVITY WILL BE CONFINED. SUPPOSE ITS PLAUSIBLE WE GET A FEW ELEVATED SHOWERS TO DEVELOP ALONG THE ADVANCING THETA-E GRADIENT ALTHOUGH LAPSE RATES ALOFT ARE JUST NOT THAT SUPPORTIVE OF CONVECTION. IN THE END...FOR CONTINUITY AND COLLABORATION WITH SURROUNDING OFFICES...DECIDED TO MAINTAIN CHANCE POPS FOR SHOWERS OVER NW LOWER MICHIGAN OVERNIGHT BUT HAVE TRIMMED POPS BACK TO 30 PERCENT OR LESS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 352 AM EDT FRI MAY 17 2013 A WARMER AND PROGRESSIVELY MORE MOIST SOUTHEASTERLY FLOW WILL LEAD TO CHANCES FOR SHOWERS THIS WEEKEND. THERE WILL BE CHANCES FOR SHOWERS AND EVEN THUNDERSTORMS EARLY NEXT WEEK WHICH WILL BECOME LIKELY BY THE MIDDLE OF NEXT WEEK...AS A CUTOFF UPPER TROUGH APPROACHES FROM OUR SOUTHWEST. FINALLY...CONDITIONS MOST LIKELY DRY OUT BY THURSDAY AS THIS SYSTEM RETREATS TO THE SOUTHEAST. THE MAIN LONG TERM FORECAST CONCERNS REVOLVE AROUND POPS AND HOW MUCH IT WILL WARM UP THIS WEEKEND INTO EARLY NEXT WEEK. SATURDAY AND SUNDAY...MODELS ARE ONLY IN FAIR AGREEMENT ON THE TIMING AND AMOUNT OF MOISTURE ADVECTION INTO THE REGION AS THETA-E RIDGING APPROACHES THE FORECAST AREA BUT WEAKENS AS IT DOES SO. THIS IS IN RESPONSE TO A DECAYING AREA OF LOW PRESSURE MOVING BY TO THE NORTHWEST. IT IS STILL UNCERTAIN IF IT WILL MOISTEN UP ENOUGH ACROSS NORTHERN MICHIGAN TO ACTUALLY RAIN...AS THE MAIN ACTION LOOKS TO REMAIN TO OUR WEST. SO WILL BACK OFF ON POPS TO SLIGHT AND LOW CHANCES FOR SHOWERS. HIGHS SATURDAY RANGING FROM THE MIDDLE 60S TO MIDDLE 70S...WITH THE WARMER 70S TO LOWER 80S ON SUNDAY EXPECTED. LOWS SATURDAY NIGHT IN THE MIDDLE 40S TO LOWER 50S. MONDAY THROUGH THURSDAY...SHOWERS AND THUNDERSTORM CHANCES INCREASE MONDAY THEN BECOME LIKELY MONDAY NIGHT INTO WEDNESDAY AS A CUTOFF UPPER LEVEL TROUGH AND WARM FRONT APPROACH FROM THE SOUTHWEST. EXTENDED MODELS THEN VARY ON THE TIMING OF DRYING FROM THE NORTH...BUT WILL PENCIL THURSDAY IN AS A DRY DAY AS THIS SYSTEM IS SHOWN TO SLOWLY RETREAT TO OUR SOUTHEAST. REMAINING WARM WITH HIGHS IN THE 70S TO LOWER 80S MONDAY...FOLLOWED BY A SLOW COOLING TREND WITH TEMPERATURES ENDING UP IN THE UPPER 50S TO LOWER 60S FOR HIGHS BY THURSDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 116 PM EDT FRI MAY 17 2013 VFR CONDITIONS EXPECTED. EXTENSIVE DECK OF HIGH AND MID LEVEL CLOUDS WILL CONTINUE TO AFFECT ALL TAF SITES RIGHT INTO SATURDAY MORNING. LIGHT RAINS ALREADY OCCURRING AT KMBL...AND SHOULD CONTINUE TO DO SO FOR THE NEXT FEW HOURS. RAINS MAY EDGE NORTH TO TVC LATER THIS AFTERNOON...ALTHOUGH WITH NO IMPACT TO VIS. LIGHT WINDS WILL REMAIN ACROSS THE AREA. && .MARINE... ISSUED AT 352 AM EDT FRI MAY 17 2013 LIGHT WINDS/LOW WAVES WILL PREVAIL ON THE LAKES TODAY AND TONIGHT WITH NO MARINE HEADLINES NEEDED. SOUTH-SOUTHEAST FLOW INCREASES SATURDAY AND SATURDAY NIGHT AND A HANDFUL OF SMALL CRAFT ADVISORIES MAY BE NEEDED. AT THAT TIME. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...MB SYNOPSIS...AS SHORT TERM...BA LONG TERM...AS AVIATION...MB MARINE...BA
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
104 PM EDT FRI MAY 17 2013 LATEST UPDATE... AVIATION .SYNOPSIS... ISSUED AT 334 AM EDT FRI MAY 17 2013 MORE CLOUDS WILL MOVE INTO THE AREA TODAY AS A SYSTEM TO OUR WEST TRIES TO MOVE IN. DRY LOW LEVELS WILL KEEP RAIN CHANCES NEAR ZERO FOR THE AREA. SOME LOW CHANCES OF RAIN WILL BE POSSIBLE TONIGHT AND EARLY SATURDAY AS A FRONTAL SYSTEM MOVES BY JUST NORTHWEST OF THE AREA. CONDITIONS SHOULD CLEAR OUT A BIT FOR LATER SATURDAY AND SUNDAY WITH WARM TEMPERATURES EXPECTED. BETTER CHANCES FOR RAINFALL WILL COME TOWARD MONDAY AND LINGER THROUGH WEDNESDAY NEXT WEEK. && .UPDATE... ISSUED AT 1121 AM EDT FRI MAY 17 2013 PRECIPITATION MOVING OFF THE WI SHORELINE HAS BEEN SLOW TO DIMINISH. GFS 06Z RUN SEEMED TO HAVE A BETTER HANDLE ON THE PRECIPITATION THAN THE NEW NAM. HRRR 12Z RUN AND OLD GFS PAINT PRECIPITATION ACROSS MUCH OF NRN ZONES...NORTH OF MKG TO GRR WITH PRECIPITAITON THIS AFTERNOON. WILL BUMP UP POPS AND LOWER TEMPERATURES FOR THIS REGION. UPDATE ISSUED AT 949 AM EDT FRI MAY 17 2013 ADDED A FEW RAIN SHOWERS TO THE FORECAST FOR LUDINGTON TO NEAR CADILLAC. RADAR TRENDS SHOW INCREASING RETURNS AND THE OBSERVATION OUT OF CADILLAC INDICATED THAT THE PRECIPITATION WAS REACHING THE GROUND. AM MONITORING THE WEAKENING THUNDERSTORMS OVER IN ERN WISCONSIN. MAY NEED TO ADD SOME PRECIPITATION TO THE MUSKEGON FORECAST AS WELL IF THEY DO NOT WEAKEN QUICKLY ENOUGH. I DID ADJUST TEMPERATURES DOWNWARD SLIGHTLY FOR NORTHERN ZONES DUE TO THE CLOUDS AND PRECIPITATION. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 334 AM EDT FRI MAY 17 2013 THE MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING PCPN CHCS THROUGH THE PERIOD. MOST OF THE PERIOD THROUGH THE WEEKEND LOOKS DRY...HOWEVER THERE ARE A COUPLE OF PERIODS WHERE RAIN POTENTIAL HAS TO BE ADDRESSED. WE EXPECT THAT THE AREA WILL STAY DRY DURING THE DAY TODAY. HIGH CLOUDS STREAMING IN FROM THE WEST ARE SHROUDING THE AREA PRETTY WELL THIS MORNING. SOME MID CLOUD COVER IS SHOWING UP OVER WEST CENTRAL AREAS OF THE CWFA. THERE IS SOME MOISTURE TRANSPORT/THETA E ADVECTION TAKING PLACE IN THE MID LEVELS. THE BEST PUSH OF EACH IS OCCURRING FURTHER WEST IN WI. IN ADDITION...THE EASTERLY FLOW IS CONTINUING TO FEED DRIER AIR IN ACROSS THE AREA. THESE FACTORS SHOULD KEEP THE ENTIRE AREA DRY TODAY. TEMPS WILL LIKELY BE A COUPLE OF DEGREES COOLER TODAY WITH LESS SOLAR INSOLATION. THE FIRST CHC OF RAIN THAT COULD OCCUR WOULD BE DURING THE PERIOD FROM TONIGHT INTO SAT MORNING ACROSS THE N/NW COUNTIES. WE HAVE ADDED A SLIGHT CHC OF SHOWERS TO THE N/NW COUNTIES. THE BEST MID LEVEL THETA E ADVECTION/MOISTURE TRANSPORT CONTINUES TO BE W/NW OF THE AREA. THERE ARE SOME SOLUTIONS SHOWING THERE COULD BE JUST ENOUGH FORCING AND DEEP ENOUGH MOISTURE TO GENERATE ENOUGH PCPN TO REACH THE GROUND THROUGH THE DRIER LOWER LEVELS. BY SAT AFTERNOON...WE SEE SUFFICIENT DIGGING OF THE WRN TROUGH AND RESULTANT BUILDING OF THE UPPER RIDGE OVER THE AREA TO PUSH THE CLOUDS AND PCPN WELL NORTH OF THE CWFA. MORE SUNSHINE COMPARED TO THIS AFTERNOON WILL HELP TO WORK ON THE WARMING H850 TEMPS TO AROUND 12-13C AND SUPPORT HIGHS AROUND 80. THE LOW LEVEL FLOW WILL BE VEERING A BIT TO THE S/SE AS THE HUDSON BAY RIDGE SHIFTS EAST. THIS WILL HELP TO START ADVECTING SOMEWHAT HIGHER DEW POINTS INTO THE AREA. FCST SOUNDINGS SHOW THAT THE LOW LEVELS WILL STILL BE JUST A LITTLE TOO DRY YET TO ALLOW FOR ANY POP UP DIURNAL CONVECTION ALONG ANY BOUNDARIES. WE WILL SEE MORE SUNSHINE ON SUN WITH TEMPS INCREASING A CATEGORY AS TEMPS ALOFT UNDER THE RIDGE INCREASE A COUPLE OF DEGREES C. SUN MIGHT SEE A SLIGHTLY BETTER CHC FOR A POP UP SHOWER DURING THE AFTERNOON HOURS AS BETTER LOW LEVEL MOISTURE DOES ADVECT IN. FCST SOUNDINGS INDICATE THAT THE MID AND UPPER LEVELS MAY BE JUST A TAD TOO WARM YET WITH THE UPPER RIDGE OVERHEAD TO ALLOW SHOWERS TO FORM. THE CHC IS NOT ZERO...HOWEVER IT LOOKS JUST A LITTLE TOO LOW AT THIS TIME TO JUSTIFY ADDING IN THE CHC. .LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY) ISSUED AT 334 AM EDT FRI MAY 17 2013 LONG TERM PATTERN BEGINS WITH THE UPPER RIDGE OVERHEAD AND AN UPPER LOW ACROSS THE NORTHERN PLAINS. THE RIDGE GRADUALLY SHIFTS SOUTH AND EAST ALLOWING THE GREAT LAKES TO BECOME MORE UNDER THE INFLUENCE OF THE UPPER LOW NEXT WEEK. THE UPPER LOW FILLS WITH TIME AND BECOMES ABSORBED INTO A EASTERN CANADIAN UPPER TROUGH. BOTH THE GFS AND ECMWF PAINT THIS SCENARIO. AT THE SURFACE LOW PRESSURE WILL GRADUALLY MOVE INTO THE GREAT LAKES STATES FROM THE WEST INTO MID WEEK. ISOLATED SHOWERS AND STORMS APPEAR POSSIBLE SUNDAY NIGHT...WITH CHANCES RAMPING UP TO LIKELY FROM TUESDAY INTO WEDNESDAY AS THE LOW AND A SURFACE WARM FRONT WILL BE IN THE AREA. THE THUNDER THREAT DIMINISHES INTO WEDNESDAY NIGHT AND THURSDAY AND HAVE SHOWERS ONLY IN THE FORECAST DURING THESE PERIODS. THE LONG TERM PERIOD LOOKS TO BE WET OVERALL...WITH RAINFALL IN EXCESS OF AN INCH POSSIBLE AS THE UPPER LOW SLOWLY MOVES THROUGH THE REGION. TEMPERATURES WILL START OUT WARM IN SOUTHERLY FLOW...TRENDING BACK TOWARD NORMAL INTO MID WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 104 PM EDT FRI MAY 17 2013 A STATIONARY FRONT OVER LOWER MICHIGAN WILL CONTINUE TO BE A FOCUS FOR A MID CLOUD DECK THROUGH THE PERIOD. SHOWERS SEEN ON CURRENT RADAR WILL MOSTLY STAY NORTH OF THE TAF SITES. HOWEVER A SPRINKLE OR TWO CAN/T BE RULED OUT A KMKG BUT THE PROBABILITY WAS LOW ENOUGH TO LEAVE OUT OF THE TAFS. && .MARINE... ISSUED AT 1121 AM EDT FRI MAY 17 2013 EXPANDED THE MENTION OF RAIN IN THE FORECAST FOR NORTHERN MARINE ZONES. && .FIRE WEATHER... ISSUED AT 334 AM EDT FRI MAY 17 2013 CONDITIONS LOOK TO BE A SLIGHT BIT BETTER THAN THU WITH REGARD TO FIRE DANGER...ALTHOUGH THE FIRE DANGER WILL REMAIN ELEVATED. MORE CLOUD COVER WILL LIMIT THE AMOUNT OF HEATING AND THE MIXING DOWN OF DRIER AIR. CONDITIONS WILL ONCE AGAIN APPROACH RED FLAG CRITERIA... HOWEVER WE EXPECT RH/S TO REMAIN JUST SHY OF THE RED FLAG CRITERIA....WINDS TO REMAIN JUST UNDER CRITERIA WITH A FEW GUSTS TO NEAR CRITERIA...AND TEMPS RIGHT AROUND THE THRESHOLD OF 75 DEGREES. WE WILL NEED TO MONITOR THE SITUATION THIS AFTERNOON. DEW POINTS SHOULD COME UP SOME OVER THE WEEKEND AS THE FLOW BECOMES A LITTLE MORE SOUTHERLY AND MOISTURE WILL ADVECT INTO THE AREA. THIS SHOULD KEEP RED FLAG CRITERIA FROM BEING REACHED. && .HYDROLOGY... ISSUED AT 334 AM EDT FRI MAY 17 2013 WE WILL NOT SEE ANY HYDROLOGY ISSUES THROUGH THE WEEKEND WITH LIKELY NO RAIN AT ALL. THE CHANCES OF ANY HYDROLOGY ISSUES MON-WED NEXT WEEK WITH RAINFALL WITH THE SYSTEM DO NOT LOOK THAT GREAT EITHER. THE SURFACE OF THE SOIL AROUND THE AREA HAS DRIED CONSIDERABLY...AND RIVER/STREAM LEVELS HAVE RETURNED TO NEAR AVERAGE FLOWS. THE MODELS ARE SHOWING RAINFALL AMOUNTS OF OVER AN INCH POSSIBLE FROM MON-WED. THIS SHOULD NOT ALL COME AT ONCE...AND THE GROUND SHOULD SOAK IT UP PRETTY WELL. RIVER LEVELS WILL COME UP...HOWEVER WE DO NOT EXPECT ANY NOTABLE ISSUES AT THIS TIME. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ UPDATE...MJS SYNOPSIS...NJJ SHORT TERM...NJJ LONG TERM...DUKE AVIATION...93 FIRE WEATHER...NJJ HYDROLOGY...NJJ MARINE...MJS
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1252 PM CDT FRI MAY 17 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 313 AM CDT FRI MAY 17 2013 THE MAIN FEATURE OF INTEREST TODAY IS THE UPPER LOW WHICH PROFILER AND WATER VAPOR SUGGEST IS CURRENTLY LOCATED ACROSS EXTREME SRN MO NEAR WEST PLAINS. THE MODELS ARE IN RELATIVELY GOOD AGREEMENT TRACKING THE LOW E/NEWD TODAY WITH THE MORE SRN POSITION OF THE LOCAL WRF AND RUC PREFERRED. THIS TRACK WOULD TAKE THE LOW ACROSS THE EASTERN OZARKS THIS MORNING AND INTO SRN IL THIS AFTENOON. THE BIGGEST UNCERTAINTY WITH THIS SYSTEM IS THE N/NW EXTENT OF PRECIPITATION AND COVERAGE. CLOUD TOPS HAVE BEEN COOLING THE LAST FEW HOURS IS ASSOCIATION WITH AN INCREASING AMOUNT OF SHOWERS. THE EXPLICIT GUIDANCE GENERALLY DEPICTS SCATTERED COVERAGE DIMINISHING WITH NORTHWARD EXTENT. THIS SEEMS REASONABLE AND HAS BEEN GENERALLY ACCEPTED WITH THE HIGHEST POPS ACROSS SE MO INTO SRN IL. THE THREAT OF CONVECTION SHOULD INCREASE LATER THIS MORNING IS ASSOCIATION WITH HEATING AND DESTABILIZATION. THE UPPER LOW SHOULD BE IN SRN IL BY EARLY EVENING...DEPARTING TO THE EAST NORTHEAST. ANY PRECIPITATION IN THE WAKE OF THE LOW SHOULD BE STRONGLY TIED TO HEATING...DISSIPATING DURING THE EVENING. GLASS .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 313 AM CDT FRI MAY 17 2013 SATURDAY LOOKS LARGELY DRY AS A RIDGE ALOFT BUILDS INTO THE AREA IN ASSOCIATION WITH OVERALL UPSTREAM AMPLIFICATION. LOW LEVEL WAA WILL INCREASE AND THIS COMBINED WITH LESS CLOUD COVER WILL RESULT IN WARMER TEMPERATURES. THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL RE-ENTER THE PICTURE ON SAT NIGHT IN RESPONSE TO LOW LEVEL WAA/MCON VIA A SWLY LLJ...BRINGING THE POTENTIAL FOR ELEVATED ACTIVITY TO THE NORTH OF A SLOWLY LIFTING WARM FRONT. THE HIGHEST PROBABILIT AT THIS TIME APPEARS TO BE ACROSS NRN MO INT CENTRAL IL. THERE COULD BE ONGOING/RESIDUAL ELEVATED ACTIVITY NORTH OF THE WARM FRONT ACROSS NE MO/WEST CENTRAL IL ON SUNDAY MORNING. OTHERWISE INCREASING SOUTHERLY FLOW AND WAA SHOULD RESULT IN CONTINUED WARMER TEMPERATURES WITH SOME LOCATIONS PUSHING 90 DEGREES. A VERY ACTIVE PERIOD WILL BEGIN TO UNFOLD LATE SUNDAY AFTERNOON AND CONTINUE THROUGH AT LEAST TUESDAY NIGHT AS RATHER DEEP AND BROAD UPPER TROF/UPPER LOW MOVES SLOWLY EAST AND A SERIES OF SHORT WAVES EJECT E/NEWD. A MOIST AND VERY UNSTABLE AIR MASS WILL BE IN PLACE AND THIS COMBINED WITH FAVORABLE DEEP LAYER SHEAR WILL SUPPORT MULTIPLE SEVERE WEATHER EPISODES OVER A 3 DAY PERIOD MIGRATING WEST TO EAST ACROSS THE CWA WITH THE MOST ACTIVE PERIOD FROM MONDAY THROUGH TUESDAY NIGHT. GLASS && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1233 PM CDT FRI MAY 17 2013 A LOW PRESSURE SYSTEM CONTINUES TO SLOWLY SPIN EASTWARD ACROSS SOUTHERN MO AND INTO THE OHIO VALLEY...WITH ASSOCIATED PRECIPITATION CONTINUING TO PERCOLATE NORTHWARD OVER EASTERN MO AND SOUTHERN AND SOUTHWEST IL. HAVE GONE WITH MENTION OF VCSH FOR METRO TAF SITES THROUGH THIS EVENING...AS IT APPEARS THAT THE MAIN FOCUS FOR TSRA SHOULD REMAIN WELL SOUTHEAST OF THE TERMINALS. LOSS OF HEATING AFTER SUNSET SHOULD ACT TO STYMIE ANY ADDITIONAL DEVELOPMENT IN OUR AREA. CONDITIONS ARE EXPECTED TO REMAIN LOW-END VFR...THOUGH MVFR CONDITIONS COULD ACCOMPANY SOME OF THE SHOWERS. FOR TONIGHT THROUGH SATURDAY MORNING...HAVE MAINTAINED TAF TRENDS FROM THE PREVIOUS ISSUANCE FOR THE DEVELOPMENT OF FOG ACROSS MUCH OF THE REGION. GIVEN AMPLE MOISTURE AND LIGHT/VAR WINDS EXPECTED OVERNIGHT...EXPECT MVFR DECREASING TO IFR FOG TO IMPACT KSTL AND KSUS...WITH VLIFR POSSIBLE FOR KCOU. THERE MAY ALSO BE SOME FOG DEVELOPMENT FOR A FEW HOURS PRIOR TO DAYBREAK AT KUIN...THOUGH DO NOT EXPECT CONDITIONS TO DROP BELOW MVFR AT THIS TIME. GRADUAL IMPROVEMENT WILL OCCUR SATURDAY MORNING...WITH CIGS BECOMING SCT VFR AS A RIDGE BUILDS INTO EASTERN MO. SPECIFICS FOR KSTL... SHOWERS CONTINUE TO PERCOLATE ACROSS EASTERN MO THIS AFTERNOON DUE TO A SLOW MOVING LOW PRESSURE SYSTEM...THROUGH ARE EXPECTED TO TAPER OFF AFTER SUNSET WITH A LOSS OF DAYTIME HEATING. WHILE A RUMBLE OF THUNDER CANNOT BE RULED OUT...FEEL THAT THE FOCUS FOR THUNDERSTORM ACTIVITY REMAINS WELL SOUTHEAST OF THE TERMINAL...AND THUS HAVE CONTINUED MENTION OF VCSH. LOW-END VFR CONDITIONS WILL PREVAIL TODAY...POSSIBLY MVFR AS SHOWERS MOVE THROUGH THE AREA...THOUGH WILL GENERALLY BE ON THE CUSP BETWEEN MVFR AND VFR UNTIL LATE TONIGHT. AMPLE MOISTURE AND LIGHT/VAR WINDS OVERNIGHT WILL RESULT IN MVFR FOG DEVELOPMENT AOA 04Z...DECREASING TO IFR AFTER 07Z...WITH LITTLE IMPROVEMENT EXPECTED UNTIL AFTER SUNRISE SATURDAY MORNING. OTHERWISE...SATURDAY IS EXPECTED TO BE DRY...WITH CIGS BECOMING SCT VFR BY LATE MORNING/EARLY AFTERNOON. JP && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1229 PM CDT Fri May 17 2013 .SHORT TERM...(Today through Saturday night) Issued at 403 AM CDT FRI MAY 17 2013 Closed upper low over extreme north central AR will continue an eastward track and move away from the CWA today. Could see an isolated shower or storm over the far eastern counties later this morning and early afternoon as any remaining vorticity lobes rotate cyclonically westward. Stratus has formed over the southern CWA. These clouds on the northwest side of the upper low an increasingly moist boundary layer. 06z RAP has best handle on the current low cloud trends and followed. Airmass over the CWA is very similar to yesterday. However, except for the far northwest corner of MO believe max temperatures today may be a few degrees cooler than yesterday due to increased cloud cover. The earlier upstream convection over KS and NE was tied to a couple of weak vorticity lobes. Convection has all but dissipated and dont` expect it to reform today. Shortwave ridging aloft is progged to amplify as it moves east across the Central and Southern Plains this afternoon through Saturday. This should yield dry and warmer conditions on Saturday. Expect max temperatures in the middle to upper 80s. Saturday night is looking a tad more interesting as it no longer looks dry. NAM/GFS/ECMWF/GEM have been giving signals for the past couple of runs that elevated convection will form Saturday evening over eastern KS/western MO and quickly advance northeast Saturday night. With a stout elevated mixed layer providing an impediment to surface based convection, any activity will need to rely on isentropic ascent and a ramping up of the h8 low level jet.....and we have that. So, have no qualms in adding at least slight chance PoPs for Saturday night to most of the CWA. Even went with chance PoPs over the northeastern CWA as the initial activity will have had time to increase in coverage as it moves quickly northeast. .LONG TERM...(Sunday through Thursday) Issued at 403 AM CDT FRI MAY 17 2013 For Sunday, there remains a good chance for severe weather from the afternoon into the overnight hours. A trough is expected to move into the Plains by Sunday afternoon leading to a surface low that will move to our north. This will result in the entire area being in a broad warm sector with dewpoints likely in the mid to upper 60s. Model soundings show a strong CAP over the region but also with the potential for elevated showers/storms earlier in the day. This possible area of precipitation should move east into the Mississippi Valley by the afternoon leaving eastern Kansas and western Missouri to see better destabilization during the afternoon. CAPE values in the 2500 to 3500 J/kg range look likely given forecast dewpoints so we will see moderate to strong instability build across our western zones. The finer scale details of what impact the convection earlier in day will have will only be able to be resolved during the nowcast period. But strong instability and 0-6KM shear in the 40 to 50 kt range, oriented more normal to any initiating boundary, indicates supercells would be the most likely convective mode initially. Hodographs show a good amount of curvature by the afternoon and this is increased during the evening as the low level jet restrengthens overhead. Storms will likely initiate over eastern Kansas during the afternoon hours and become supercells. As winds veer into the evening and overnight hours storms should organize into more of a line/ convective complex. Large hail, damaging winds and a few tornadoes are possible with the initial storms before the convective mode changes and damaging winds becomes the primary concern. Monday will be greatly dependent upon what happens Sunday night, and as such confidence is quite a bit lower. Latest guidance suggest that the front will be nearly east of us by the evening hours with winds across the area veered southwesterly. Shear and instability are still supportive of severe weather, but the chances should be either across our eastern to southern zones or even east of the forecast area. We will really need to see how the weather pans out Sunday before a saying anything with any level of certainty. For the remainder of the extended forecast, the upper trough that affected the area Sunday and Monday should have cutoff over the Upper Midwest. Another segment of the upper trough will move through Wednesday and as a result there may be a few showers or storms across northern Missouri into central and eastern Missouri. A few showers and storm will remain a possibility into Thursday as northern portions of the forecast are still under the influence of the Upper Midwest upper low. The effects of the upper low will diminish by Friday as upper ridging spreads into the Plains. This will result in a warm up with drier conditions more likely for the weekend. The severe potential looks rather low for this stretch of time. && .AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon) Issued at 1228 PM CDT FRI MAY 17 2013 Widespread MVFR cigs are gradually lifting and scattering, and expect cumulus field to lift into VFR across the entire region by late afternoon. Most guidance is suggesting the possibility of IFR cigs/vsbys redeveloping a bit further north and east late tonight, possibly affecting the KC terminals and parts of ern KS/wrn MO. Confidence on this is not high, and increased SE flow should prevent widespread vsby restrictions, but probabilities for IFR cigs are high enough for now to introduce this into the TAFs right around sunrise. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ SHORT TERM...MJ LONG TERM...CDB AVIATION...Hawblitzel
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1221 PM CDT FRI MAY 17 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 406 AM CDT FRI MAY 17 2013 ANOTHER SEASONABLY WARM AFTERNOON IS EXPECTED ACROSS THE REGION AS WEAK UPPER LEVEL RIDING WORKS ITS WAY IN FROM THE WEST. EARLY THIS MORNING...SOME SHOWER AND THUNDERSTORM ACTIVITY HAS DEVELOPED TO THE WEST OF THE LOCAL AREA...LIKELY A FACTOR OF THE LOW LEVEL JET PROVIDING JUST ENOUGH FORCING ACROSS WESTERN KANSAS EARLY THIS MORNING TO SPARK SOME CONVECTION. HOWEVER WITH THIS ACTIVITY SHOWING SIGNS OF DIMINISHING AND LITTLE INSTABILITY TO KEEP IT GOING AS IT APPROACHES THE LOCAL AREA...DECIDED TO JUST ADD A SLIGHT CHANCE OF SPRINKLES ACROSS THE WESTERN FRINGES OF OUR FORECAST AREA THROUGH 8 AM TO ACCOUNT FOR ANY REMNANTS OF THIS CONVECTION AS IT WORKS EAST. OTHERWISE...HAVE SEEN SOME PATCHY FOG DEVELOP ACROSS AROUND LXN AND ODX EARLY THIS MORNING AS TEMPERATURES HAVE FALLEN TO REACH THE DEWPOINTS AT THESE LOCATIONS THE PAST COUPLE OF HOURS...AND THINK SOME FURTHER DEVELOPMENT WILL BE POSSIBLE OVER THE NEXT FEW HOURS...GENERALLY WEST OF HIGHWAY 281. HRRR AND SREF HAVE BOTH BACKED OFF ON POTENTIAL FOG DEVELOPMENT FOR THIS MORNING...AND EXPECT ANY FOG THAT DOES MANAGE TO DEVELOP TO BE FAIRLY PATCHY AND SHORT LIVED...AND CORRESPONDINGLY TRIMMED BACK COVERAGE FROM PREVIOUS FORECAST. FOR THIS AFTERNOON...EXPECT TEMPERATURES TO CLIMB BACK INTO THE MID AND UPPER 80S ACROSS THE ENTIRE FORECAST AREA AS PARTLY CLOUDY TO MOSTLY SUNNY SKIES WILL WORK THEIR WAY IN ACROSS THE REGION AS THE RIDGE TRANSITIONS EASTWARD. ADDITIONALLY...WITH THE RIDGE AXIS MOVING OVERHEAD...850MB TEMPS WILL CLIMB A COUPLE OF DEGREES FROM YESTERDAYS VALUES...FURTHER AIDING IN A SEASONABLY WARM AFTERNOON. AT THE SURFACE...EXPECT A SURFACE TROUGH TO DEVELOP ON THE LEE SIDE OF THE ROCKIES BY EARLY AFTERNOON...AND THIS SHOULD HELP INCREASE THE PRESSURE GRADIENT JUST ENOUGH TO RESULT IN BREEZY SOUTHERLY WINDS...GENERALLY 15 TO 25 MPH IN MOST SPOTS. FOR TONIGHT...SOME OF THE GUIDANCE IS ATTEMPTING TO DEVELOP SOME CONVECTION ACROSS THE HIGH PLAINS AND TRANSITION IT EASTWARD AROUND SUNSET. WHILE THERE WILL BE PLENTY OF INSTABILITY TO JUSTIFY CONVECTION TO OUR WEST...A DECENT CAP IS FORECAST AROUND 800 MB WITH LITTLE IN THE WAY OF FORCING TO JUSTIFY MUCH CONVECTION ACROSS THE LOCAL AREA. EVEN SO...WITH 00Z WRF BEING THE MOST AGGRESSIVE TRANSLATING SOME OF THE REMNANTS OF THE HIGH PLAINS CONVECTION ACROSS THE LOCAL AREA DURING THE EVENING HOURS...FELT JUSTIFIED ADDING A FEW SPRINKLES TO THE NORTHWESTERN QUADRANT OF THE LOCAL AREA JUST IN CASE A FEW SHOWERS ARE ABLE TO MAINTAIN THEMSELVES AS THEY TRACK EAST. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 408 AM CDT FRI MAY 17 2013 THUNDERSTORM CHANCES THIS WEEKEND WILL BE THE PRIMARY FOCUS OF LONG TERM. IT SHOULD BE NOTED THAT THERE ARE CHANCES FOR PRECIPITATION NEARLY EVERYDAY OVER THE LONG TERM...BUT THE CHANCE FOR SEVERE THUNDERSTORMS APPEARS TO BE BEST ON SATURDAY AT THE MOMENT. AN UPPER LEVEL TROUGH WILL BEGIN TRANSITIONING OVER THE WEST COAST TODAY AND WILL EVENTUALLY MOVE EASTWARD INTO THE INTERMOUNTAIN WEST ON SATURDAY. AT THE SURFACE ON SATURDAY...A LEE LOW WILL FORM AHEAD OF THE UPPER LEVEL TROUGH...AND A COLD FRONT WILL DRAPE INTO NEBRASKA WHICH SHOULD HELP TO INITIATE THUNDERSTORMS ACROSS THE OUTLOOK AREA LATER IN THE AFTERNOON. THERE WILL BE A STRONG CAPPING INVERSION IN PLACE AT THE MID-LEVELS...SO THIS WILL NEED TO ERODE/BREAK BEFORE ANY CONVECTION CAN INITIALIZE. A FEW THINGS SHOULD HELP TO GET STORMS INITIATED LATER IN THE AFTERNOON THOUGH. FOR ONE...THE ADVECTION OF STEEPER LAPSE RATES IN THE MID-LEVELS WILL HELP WEAKEN THIS CAP. SECONDLY...THE COLD FRONT PROGGED TO SLIDE OVER THE REGION SHOULD SERVE AS A GOOD LIFTING MECHANISM TO HELP GET CONVECTION STARTED IN THE AFTERNOON. LASTLY...MODERATE TO STRONG INSTABILITY ON THE ORDER OF 3000-4000 J/KG OF MLCAPE IS FORECAST BY 00Z SUNDAY...SO ANY STORMS THAT DO FORM WILL HAVE THE ABILITY TO BECOME STRONG TO SEVERE. AS THE EVENT UNFOLDS LATER INTO THE EVENING...THE FORMATION ON AN MCS IS DEFINITELY POSSIBLY AND SHOULD POSE A PRIMARY THREAT OF DAMAGING WINDS. HAIL WILL BE THE PRIMARY THREAT EARLY IN THE EVENT...ESPECIALLY THE MORE ISOLATED/DISCRETE CELLS WITH STRONG UPDRAFTS. ITS ALSO WORTH NOTING THE NAM...GFS...AND EC ALL SHOW STRONG 0-1 KM BULK SHEAR ON THE ORDER OF 25 TO 30 KTS. DEEP LAYER SHEAR WAS NOT AS IMPRESSIVE BUT STILL HAD VALUES AROUND 35 KTS. THE SHEAR ENVIRONMENT COUPLED WITH STRONG INSTABILITY WOULD SUGGEST SUPERCELLS COULD FORM AND WITH ANY SUPERCELL...THERE WILL ALSO BE A TORNADO THREAT. MOVING INTO SUNDAY...THUNDERSTORMS WILL LIKELY CONTINUE MOVING EASTWARD ACROSS THE OUTLOOK AREA. THE SEVERE THREAT WILL BE OVERALL LIMITED...BUT OUR EASTERN COUNTIES COULD POTENTIALLY SEE THE SEVERE THREAT CONTINUE INTO THE AFTERNOON HOURS ON SUNDAY...PRIMARILY EAST OF HIGHWAY 281. NEXT WEEK WILL HAVE POPS ANYWHERE FROM 10 TO 30 PERCENT NEARLY EVERYDAY. THESE POPS ARE ROOTED IN THE TROUGH CURRENTLY OVER THE WEST COAST WHICH IS FORECAST TO MEANDER AROUND THE GREAT PLAINS NEXT WEEK. THE BIGGEST DISADVANTAGE IN THE LONG TERM IS THE LACK OF CONSISTENCY AND AGREEMENT BETWEEN THE MODELS. THROUGH THE WEEKEND...TEMPERATURES WILL BE ABOVE NORMAL...WHILE NEXT WEEK WILL BE CLOSER TO NORMAL FOR THIS TIME OF YEAR. HIGHS ON TUESDAY APPEAR TO BE THE ONE EXCEPTION...WITH TEMPERATURES MORE LIKELY TO BE SLIGHTLY BELOW NORMAL FOR THIS TIME OF YEAR. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1220 PM CDT FRI MAY 17 2013 A FEW CIRRUS ARE MOVING THROUGH THE KGRI TERMINAL AREA THIS AFTERNOON AND WILL CONTINUE INTO THIS EVENING. LATE TONIGHT LOW LEVEL MOISTURE WILL PUSH INTO THE AREA. THIS WILL BRING IN LOW CLOUDS AND SOME FOG. EXPECT THERE TO BE IFR CONDITIONS. THERE IS AN OFF CHANCE THAT THERE MAY BE SOME LIFR CONDITIONS...BUT WILL WAIT TO SEE HOW MUCH OF THE LOW LEVEL MOISTURE GETS INTO THE KGRI TERMINAL AREA. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...SAR LONG TERM...GUERRERO AVIATION...JCB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
255 PM EDT FRI MAY 17 2013 .SYNOPSIS... A COLD FRONT OVER CENTRAL VIRGINIA WILL SAG SOUTH AND BE LOCATED NEAR THE NORTH CAROLINA BORDER BY LATE TONIGHT. UPPER LEVEL LOW PRESSURE WILL CONTINUE TO MOVE EAST AND HAVE A MAJOR INFLUENCE ON THE WEATHER OF THE REGION OVER THE WEEKEND. ATLANTIC HIGH PRESSURE GRADUALLY BUILDS INTO THE CAROLINAS EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 255 PM FRIDAY... THE LATEST SURFACE ANALYSIS SHOWED A SURFACE FRONT ACROSS NORTHERN INDIANA AND OHIO...THEN BENDING SOUTHEAST ACROSS SOUTHWEST PENNSYLVANIA TOWARD FAR NORTHEAST NORTH CAROLINA. ALONG AND JUST AHEAD OF THE FRONT OVER NORTHEAST NORTH CAROLINA...INCLUDING THE COASTAL PLAIN...INSTABILITY WAS HIGHEST WITH MIXED-LAYER CAPE ON THE ORDER OF 500J/KG ON THE LATEST SPC MESOANALYSIS. GIVEN THE LIGHT WIND FIELD CONVERGENCE WAS MEAGER...AND WHILE SURFACE DEW POINTS HAD YET TO FALL AS FAR AS THE RAP FORECAST...THEY STILL HAVE FALLEN SOLIDLY INTO THE 50S OVER MOST PARTS OF CENTRAL NORTH CAROLINA. THIS HAS MADE IT DIFFICULT FOR ANY DEEP CONVECTION TO DEVELOP. GIVEN THE DIFFERENCES IN THE MOISTURE GUIDANCE AS WELL AS THE OUTPUT OF THE CONVECTION-ALLOWING MODELS...AND CONSIDERING THE NAM APPEARS SO OUT OF TOLERANCE WITH ITS FORECAST SURFACE DEW POINTS...HAVE LEANED TOWARD A CONSENSUS OF THE RAP AND GFS OVERNIGHT. THIS WOULD SUPPORT THE BETTER CHANCES OF ANY SHOWERS OR THUNDERSTORMS OVERNIGHT ALONG AND AHEAD OF THE SURFACE FRONT...MAINLY ALONG AND NORTH OF A LINE FROM ABOUT KTDF TO KRWI. THIS IS WHERE THE RAP SHOWS LOW-LEVEL MOISTURE POOLING AROUND AND AFTER 00Z...SUPPORTED MOST BY THE LOCAL RALIEGH WRF REFLECTIVITY FORECAST. IN THE RELATIVELY MORE STABLE AIR OVER THE SOUTHWEST PIEDMONT IN PARTICULAR...WILL KEEP CONDITIONS DRY UNTIL THE OVERNIGHT HOURS...AND THEN ONLY NOTE A SLIGHT CHANCE OF A SHOWER THERE AND ELSEWHERE ACROSS CENTRAL NORTH CAROLINA. IT SHOULD BE NOTED THAT SOME OF THE GUIDANCE POPS...PARTICULARLY FROM THE NAM...ARE QUITE HIGH OVERNIGHT...BUT THE NAM ALSO FORECASTS SURFACE DEW POINTS GETTING NEAR 70 OVER PARTS OF THE NORTHWEST PIEDMONT BY 21Z...WHICH CURRENTLY SEEMS UNLIKELY. UNDER A CONTINUING MID-LEVEL RIDGE AHEAD OF THE TROUGH MOVING EAST...WILL ANTICIPATE A DIURNAL REDUCTION IN CHANCES FOR PRECIPITATION FOR ONE MORE NIGHT. OVERNIGHT LOWS IN THE LOWER TO MID 60S. && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... AS OF 255 PM FRIDAY... THE TROUGH ALOFT GRADUALLY MOVES INTO CENTRAL NORTH CAROLINA SATURDAY AND SATURDAY NIGHT. WHILE DIFFERENCES CONTINUE WITH THE DETAILS IN THE GUIDANCE...INCLUDING VARIOUS WRF OUTPUT...ON A LARGE SCALE...MEAN RH INCREASES TO A MAXIMUM DURING THE PERIOD LATE SATURDAY AFTERNOON IN THE NORTHWEST PIEDMONT...AND TO ABOUT U.S. 1 OR SO SATURDAY NIGHT. THE BEST LIFT IS NORTHWEST CLOSER TO THE UPPER TROUGH...850MB THETA-E IS GREATEST IN CONJUNCTION WITH THE MEAN RELATIVE HUMIDITY...AND BY LATE SATURDAY AFTERNOON AND SATURDAY NIGHT...THE 850MB FLOW FROM THE SOUTHWEST INCREASES TO AROUND 25KT FOCUSED OVER AND NEAR THE WESTERN PIEDMONT. BUFR SOUNDINGS ESPECIALLY FROM THE GFS SHOW GREATER MOISTURE AND INSTABILITY WEST COMPARED TO EAST IN CENTRAL NORTH CAROLINA. AS A RESULT...INSTEAD OF TRYING TO INTERPRET THE VARIETY OF WRF TRENDS...HAVE FOLLOWED A PRECIPITATION FORECAST LEANING MORE TOWARD LARGE-SCALE FEATURES. THIS RESULTS IN MOSTLY CHANCE POPS FOR SATURDAY...BECOMING LIKELY IN THE IMMEDIATE TRIAD BY LATE IN THE DAY AND SPREADING LIKELY POPS TO AROUND U.S. 1 BY OVERNIGHT SATURDAY CLOSER TO 850MB LOW PRESSURE. THE LEAST CHANCES WILL BE TOWARD KGSB AND KCTZ...WHERE OVERALL MOISTURE AND LIFT ARE LEAST...CLOSER ALSO TO THE 850MB RIDGE JUST OFFSHORE. THE GFS HAS FAIRLY ROBUST PRECIPITATION AMOUNTS IN THE TRIAD OVERNIGHT SATURDAY AND THIS WILL HAVE TO BE WATCHED...BUT FOR NOW WILL FORECAST AVERAGE PRECIPITATION AMOUNTS THERE AROUND 0.75 INCH FROM LATE SATURDAY AFTERNOON THROUGH SATURDAY NIGHT. HIGHS SATURDAY NEAR 80 NORTHWEST TO THE UPPER 80S SOUTHEAST...WITH OVERNIGHT LOWS SATURDAY NIGHT IN THE MID 60S. && .LONG TERM /SUNDAY THROUGH FRIDAY/... AS OF 255 PM FRIDAY... SUNDAY THROUGH MONDAY NIGHT: CONFIDENCE IN AN UNSETTLED WEATHER PATTERN IS HIGH THROUGH MONDAY NIGHT...HOWEVER THE TIMING...COVERAGE AND INTENSITY OF PRECIPITATION IS STILL AN ISSUE. AN UPPER LEVEL SHORTWAVE DISTURBANCE ALONG THE RIDGE AXIS MOVING OVER CENTRAL NC ON SUNDAY AND MONDAY WILL AID IN THE DEVELOPMENT OF SHOWERS AND STORMS THROUGH THE PERIOD. AT H850 A TROUGH WILL EXTEND EAST FROM THE PARENT LOW OVER THE MIDWEST AND INTO TN AND THE CAROLINAS THROUGH MONDAY...WITH RIDGING TO THE NORTH FROM AN OFFSHORE HIGH. ALTHOUGH THERE ARE STILL SOME DIFFERENCES BETWEEN THE MODELS AND FROM RUN TO RUN...THE GFS AND ECMWF HAVE COME INTO BETTER AGREEMENT WITH RESPECT TO THE STRENGTH AND CHARACTER OF THE SHORTWAVE LOW...THUS WILL CONTINUE A BLEND OF THE TWO. AT THE SURFACE...THE GFS CONTINUES TO SHOW A LOW DEVELOPING IN THE LEE OF THE ROCKIES THIS WEEKEND AND DEEPENING AS IT MIGRATES SLOWLY EAST INTO EASTERN SD...EXTENDING SSE THROUGH CENTRAL OK/TX...AND A TROUGH AXIS EXTENDING EAST INTO THE MID ATLANTIC STATES. WARM MOIST SW FLOW OFF THE GULF WILL KEEP PWAT VALUES IN THE 1.5 TO 2.0 INCH RANGE THROUGH MONDAY NIGHT FUELING THE POTENTIAL FOR SOME SIGNIFICANT STORM TOTAL RAINFALL AMOUNTS GIVEN THE WEAK STEERING FLOW EXPECTED. MODEL GENERATED MLCAPE IS OF THE TALL AND SKINNY VARIETY...WITH VALUES OF 1000-1500 J/KG SUNDAY AND MONDAY. COMBINED WITH 0-6 KM BULK SHEAR VALUES OF MAINLY 10-20 KTS...EXPECT CONVECTIVE MODE TO BE MAINLY DISORGANIZED PULSE TYPE STORMS...ALTHOUGH AN ISOLATED STRONG STORM CANNOT BE RULED OUT. THE BIGGER THREAT CONTINUES TO BE FROM POTENTIALLY HEAVY RAINFALL... ESPECIALLY SUNDAY NIGHT AND MONDAY. GIVEN THE UNCERTAINTY REGARDING PRECIP AMOUNTS...HAVE DECREASED STORM TOTAL RAINFALL TOTALS FROM THE PREVIOUS FORECAST...HOWEVER WIDESPREAD 1-2 INCHES IS STILL LIKELY THROUGH MONDAY NIGHT. HIGH TEMPERATURES THROUGH THIS PERIOD CONTINUE TO BE DEPENDENT ON CLOUD COVER AND PRECIPITATION. FOR NOW...EXPECT HIGHS IN THE UPPER 70S NORTH AND LOW TO MID 80S ACROSS THE EAST AND SOUTH. OVERNIGHT LOWS WILL STAY MAINLY IN THE MID 60S. TUESDAY THROUGH FRIDAY: AS THE SHORTWAVE MOVES NORTHEAST AWAY FROM THE AREA ON TUESDAY...HIGH PRESSURE WILL BUILD INTO THE CAROLINAS FROM THE ESE...WITH RETURN FLOW OFF THE ATLANTIC AND A SLIGHT DECREASE IN FORECAST PWAT VALUES. DRY AIR ADVECTING IN AT THE MID LEVELS SHOULD DECREASE RAINFALL CHANCES THROUGH WEDNESDAY ALTHOUGH THE POSSIBILITY OF AN AFTERNOON SHOWER EXISTS. A MIDWEST LOW WILL MOVE EAST TOWARD THE MID ATLANTIC DURING THIS TIME AND THE TROUGH BECOMES ORIENTED MORE SW TO NE...WITH INCREASING PRECIPITATION CHANCES ON THURSDAY AND FRIDAY. GIVEN THE DIFFERENCES BETWEEN THE MODELS...THERE IS A GOOD DEAL OF UNCERTAINTY WITH RESPECT TO PRECIPITATION MOVING AHEAD OF THE SYSTEM. FOR NOW WILL CARRY SLIGHT CHANCES FOR SHOWERS AND STORMS DURING THE AFTERNOON HOURS THURSDAY AND FRIDAY...WITH A DRY FORECAST FOR THE OVERNIGHT HOURS. HIGH TEMPS TUESDAY AND WEDNESDAY IN THE MID TO UPPER 80S...DECREASING AGAIN THROUGH FRIDAY...UPPER 70S TO LOW 80S. OVERNIGHT LOWS REMAIN STEADY IN THE MID TO UPPER 60S. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AS OF 255 PM FRIDAY... MAINLY VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE 18Z VALID TAF PERIOD OUTSIDE OF ANY SHOWERS OR THUNDERSTORMS. THE BEST CHANCE OF A SHOWER OR THUNDERSTORM OVERNIGHT APPEARS TO BE TOWARD THE TRIAD AND KRWI...POSSIBLY AS FAR SOUTH AS KRDU...WITH LESSER POTENTIAL TOWARD KFAY. A PERIOD OF MVFR FOG IS POSSIBLE AT ALL TAF SITES LATE TONIGHT INTO EARLY SATURDAY IN AN AIR MASS THAT GRADUALLY MOISTENS AGAIN OVERNIGHT. SOME OF THE GUIDANCE SUGGESTS A SMALL POTENTIAL FOR LOW CLOUDS AT KINT...KGSO...AND KRWI...BUT THE SREF MODEL PROBABILITIES OF CLOUDS BELOW 1000FT ARE HIGHEST JUST NORTHEAST OF KRWI TOWARD KIXA...KASJ...AND KEDE AND WERE ONLY NOTED WITH FEW IN THE TAFS LATE TONIGHT INTO EARLY SATURDAY IN CENTRAL NORTH CAROLINA. BEYOND THE 18Z VALID TAF PERIOD...CHANCES FOR SHOWERS AND THUNDERSTORMS GRADUALLY INCREASE...BECOMING LIKELY IN THE TRIAD BY LATE SATURDAY AFTERNOON AND EXTENDING AT LEAST TO KRDU BY SATURDAY NIGHT AS AN UPPER-LEVEL TROUGH MOVES EAST. ALONG WITH THE SUB-VFR CONDITIONS THAT THE SHOWERS AND STORMS WOULD BRING...THERE IS A GOOD CHANCE OF IFR CONDITIONS IN LOW CLOUDS AT LEAST TOWARD KINT AND KGSO LATE SATURDAY NIGHT INTO SUNDAY MORNING...WITH SOME CHANCE OF THOSE CLOUDS EXTENDING ACROSS THE REST OF CENTRAL NORTH CAROLINA. PERIODS OF MVFR AND IFR CONDITIONS IN LOW CLOUDS...OR SHOWERS OR THUNDERSTORMS...CONTINUE INTO EARLY NEXT WEEK...WITH THE BEST POTENTIAL FOR SUSTAINED VFR CONDITIONS TUESDAY AFTERNOON INTO THE OVERNIGHT HOURS OF TUESDAY...AND AGAIN AFTER MIXING DURING THE DAY WEDNESDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DJF NEAR TERM...DJF SHORT TERM...DJF LONG TERM...KMC AVIATION...DJF
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
123 PM EDT FRI MAY 17 2013 .SYNOPSIS... WARM TEMPERATURES WILL CONTINUE INTO EARLY NEXT WEEK AS BERMUDA HIGH PRESSURE REMAINS ANCHORED OFFSHORE. A MID LEVEL DISTURBANCE WILL BRING INCREASED CHANCES OF SHOWERS AND THUNDERSTORMS OVER THE WEEKEND INTO EARLY NEXT WEEK. DRIER WEATHER IS EXPECTED THROUGH THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1:30 PM FRIDAY...CONVECTIVE DEVELOPMENT HAS BEEN MEASURED AS EXPECTED THIS AFTERNOON AS CUMULUS CLOUDS ARE JUST NOW BEGINNING TO DEVELOP. THE LATEST GUIDANCE INCLUDING THE HIGH RESOLUTION RAP AND GLOBAL GFS SHOW SOME ACTIVITY TO THE NORTH LATER THIS AFTERNOON. I HAVE TWEAKED THE POPS TO REPRESENT THIS TREND OF WHICH THE FORCING INCLUDES THE SEA BREEZE FRONT...POSSIBLY A RESIDUAL OUTFLOW FROM ACTIVITY YESTERDAY AND A BACKDOOR FRONT. FOR THE OVERNIGHT HOURS...I HAVE REMOVED POPS AFTER 0300 UTC. ENOUGH DEBRIS CLOUDINESS SHOULD REMAIN TO PREVENT ANY SIGNIFICANT FOG DEVELOPMENT. FOR THE OVERNIGHT LOWS...NUMERICAL GUIDANCE IS IN EXCELLENT AGREEMENT WITH MIDDLE 60S ACROSS THE BOARD. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...WEAK PATTERN ALOFT COUPLED WITH BERMUDA HIGH AND PIEDMONT TROUGH WILL RESULT IN AFTERNOON SHOWERS AND THUNDERSTORMS SAT AND SUN. FOR SAT FLOW ALOFT REMAINS ZONAL AND FORECAST SOUNDINGS SHOW SOME DRY AIR THROUGH THE COLUMN. STILL ANTICIPATE SOME STORM DEVELOPMENT ALONG PIEDMONT TROUGH AND SEABREEZE BUT COVERAGE AND STRENGTH WILL BE LIMITED. COVERAGE SHOULD INCREASE SUN AS DEEPER MOISTURE ARRIVES AND WEAK 5H SHORTWAVE TROUGH SLOWLY MOVES INTO BUILDING MID LEVEL RIDGE. MID LEVEL LAPSE RATES REMAIN WEAK BUT FORECAST SOUNDINGS SHOW A SIGNIFICANT INCREASE IN MOISTURE WITH PRECIPITABLE WATER VALUES AROUND 1.9 INCH BY AFTERNOON. STEEP LOW LEVEL LAPSE RATES AND PRESENCE OF PIEDMONT TROUGH AND SEABREEZE HELP GENERATE CONVECTION. DEEPER MOISTURE AND ENHANCEMENT ALOFT WILL HELP SUSTAIN DEEPER CONVECTION RESULTING IN WIDESPREAD AFTERNOON SHOWERS AND THUNDERSTORMS. WEAK MID LEVEL LAPSE RATES...LIMITED DRY LOW LEVEL AIR AND LACK OF STRONG JETTING SUGGEST STORMS WILL NOT BECOME SEVERE. HIGHS WILL BE NEAR TO SLIGHTLY ABOVE CLIMO WITH WARM ADVECTION BEING OFFSET SOMEWHAT BY CLOUD COVER...ESPECIALLY ON SUN. LOWS WILL REMAIN SEVERAL DEGREES ABOVE CLIMO EACH NIGHT. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 3 AM FRIDAY...DEEP MOISTURE AND WEAKNESS IN BUILDING MID LEVEL RIDGE LINGERS OVER THE ARE MON...ONCE AGAIN CREATING AN ENVIRONMENT SUPPORTIVE OF WIDESPREAD SHOWERS AND THUNDERSTORMS. AS IS THE CASE ON SUN SEVERE PARAMETERS ARE LACKING SO STORMS ARE EXPECTED TO REMAIN SUB-SEVERE. PRECIP CHANCES START TO DECREASE TUE AS 5H RIDGE CONTINUES TO BUILD IN FROM THE EAST AND THE WEAKNESS IN THE RIDGE FILLS IN. REMAINDER OF THE PERIOD WILL BE DOMINATED BY THE 5H RIDGE AND THE BERMUDA HIGH. FORECAST SOUNDINGS SHOW DRY AIR BELOW 12FT TUE EXPANDING THROUGH THU AS SUBSIDENCE INVERSION STRENGTHENS. ABUNDANT MOISTURE ABOVE 15K FT MAY KEEP CIRRUS AROUND THROUGH THE PERIOD BUT PRECIP CHANCES WILL BE DIMINISHED. LATE IN THE PERIOD A COLD FRONT APPROACHES FROM THE NORTHWEST BUT ITS ARRIVAL WILL BE WELL BEYOND THE END OF THE PERIOD SO IT IS NOT A FACTOR AT THIS POINT. HIGHS WILL BE WITHIN A FEW DEGREES OF CLIMO MON AND TUE BUT CLIMB WELL ABOVE CLIMO BY THE END OF THE PERIOD. LOWS WILL REMAIN WELL ABOVE CLIMO THROUGH THE PERIOD. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AS OF 18Z...EXPECT VFR THROUGH THE VALID PERIOD...WITH THE EXCEPTION OF POSSIBLE AREAS OF FOG SATURDAY MORNING. FOR THE REST OF THE DAY EXPECT SCT/BKN MID TO HIGH LEVEL CLOUDS WITH SOUTHWEST WINDS AOB 10 KTS...BECOMING MORE SOUTH ALONG THE COAST WITH THE AFTERNOON SEABREEZE. WOULD NOT COMPLETELY RULE OUT AN ISOLATED SHOWER THIS AFTERNOON...BUT CONFIDENCE IS LOW. INTO THE OVERNIGHT HOURS...CLOUD COVERAGE WILL CONTINUE...AND LIKELY INCREASE...WITH WINDS BECOMING LIGHT. TOWARDS THE EARLY MORNING HOURS ON SATURDAY...CANNOT RULE OUT PATCHY FOG...ESPECIALLY INLAND. TIME-HEIGHT ANALYSIS AND FCST SOUNDINGS SUGGEST POSSIBILITY OF FEW/SCT LOW CLOUDS IN THE MORNING AS WELL. AFTER DAYBREAK...CLOUDS WILL GRADUALLY BEGIN TO SCATTER OUT WITH SOUTHWEST WINDS AOB 8 KTS. EXTENDED OUTLOOK...CHANCE OF AFTN SHOWERS/TSTMS SATURDAY THROUGH MONDAY...OTHERWISE VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1:30 PM FRIDAY...PERSISTENCE WILL BE THE THEME FOR THE COASTAL WATERS THROUGH TONIGHT AS A SOUTHWEST FLOW OF 10-15 KNOTS PREVAILS. WAVEWATCH SEAS WILL CONTINUE IN A 2-4 FOOT RANGE. THE BACKDOOR FRONT SHOULD STAY WELL TO THE NORTH PRECLUDING ANY WIND SHIFT. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...SOUTHWEST FLOW WILL CONTINUE THROUGH THE PERIOD AS BERMUDA HIGH REMAINS IN CONTROL. GRADIENT WILL PRODUCE SPEEDS IN THE 10 TO 15 KT RANGE WITH SPEEDS EACH AFTERNOON ON THE HIGHER END OF THE RANGE. SEAS WILL RUN 2 TO 4 FT WITH SOUTHEAST SWELL BECOMING A LITTLE MORE APPARENT. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 3 AM FRIDAY...SUMMER PATTERN CONTINUES WITH BERMUDA HIGH KEEPING SOUTH TO SOUTHWEST FLOW BETWEEN 10 AND 15 KT. HIGHEST SPEEDS WILL OCCUR IN THE AFTERNOON. SEAS 2 TO 4 FT THROUGH THE PERIOD WILL BE A MIX OF WIND WAVE AND SOUTHEAST SWELL. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...SHK NEAR TERM...SHK SHORT TERM...III LONG TERM...III AVIATION...SGL
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
345 PM CDT FRI MAY 17 2013 .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 330 PM CDT FRI MAY 17 2013 THE MAIN CONCERNS WILL BE HEAVY RAIN AND SEVERE POTENTIAL. 12Z MODELS IN DECENT AGREEMENT WITH SYNOPTIC FEATURES...BUT STILL ENOUGH DIFFERENCES THAT CONFIDENCE IS LOW WITH DETAILS. WEST COAST TROUGH WILL GRADUALLY PROPAGATE EAST WITH MULTIPLE SHORTWAVES EJECTING INTO THE REGION. HARD TO PINPOINT EXACTLY WHEN AND WHERE THE BEST THUNDER CHANCES WILL BE...BUT THE MODELS DO OFFER A COUPLE STRONGER SIGNALS. THE FIRST BEST CHANCE IS TONIGHT INTO SATURDAY MORNING AS MENTIONED IN THE PREVIOUS AFD (1243PM). 18Z HRRR DOES INDICATE A THUNDERSTORM COMPLEX MOVING INTO THE SOUTHERN FA AFTER 06Z...ALONG WITH WITH ISOLATED STRONGER STORMS. THIS COMPLEX SHOULD MOVE THROUGH FAIRLY QUICKLY...WITH UP TO 0.5 INCH AREAL QPF POSSIBLE. THINKING THERE WILL BE A BRIEF BREAK IN ACTIVITY ON SATURDAY. SEVERE POTENTIAL WILL DEPEND ON HOW FAR NORTH THE SURFACE WARM FRONT WILL MAKE IT BY SATURDAY AFTERNOON. THE GEM/GFS BRING THIS FEATURE MUCH FURTHER NORTH THAN OTHER MODELS (LIKELY BECAUSE THEY ARE STRONGER WITH A SHORTWAVE INTO SOUTHERN CANADA). AT ANY RATE...GIVEN THIS TIME OF YEAR WITHOUT EVAPOTRANSPIRATION...THE NAM SEEMS TO HAVE THE CORRECT IDEA INDICATING MLCAPE 1000-1500 J/KG WITHIN THE WARM SECTOR. THIS INSTABILITY ALONG WITH DEEP LAYER SHEAR 30-35 KNOTS SHOULD BE ENOUGH FOR LIMITED SEVERE POTENTIAL WITHIN THE WARM SECTOR AS THE COLD FRONT SLOWLY PROPAGATES EAST INTO THE EVENING HOURS. THE BEST CHANCE FOR FLASH FLOODING POTENTIAL WOULD BE SATURDAY EVENING AND OVERNIGHT ALONG THE SLOW MOVING BOUNDARY. THE BIGGEST QUESTIONS AT THIS POINT WILL BE THE EXACT LOCATION OF THIS FEATURE...AND HOW QUICKLY IT WILL MOVE TO THE EAST. NOT ENOUGH CONFIDENCE FOR A FLASH FLOOD WATCH AT THIS POINT...BUT THERE IS A SLIGHT RISK FOR FLASH FLOODING ALONG AND EAST OF THE VALLEY. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 330 PM CDT FRI MAY 17 2013 SUNDAY-MONDAY...UPPER LOW WILL CLOSE OFF JUST SOUTH OF THE FA AND BRING PERIODIC SHOWERS AND THUNDERSTORMS TO THE REGION. INSTABILITY IS MUCH WEAKER BY THIS TIME...BUT GIVEN HIGH PWATS AN ADDITIONAL 1-2 INCHES OF RAINFALL IS POSSIBLE (ESPECIALLY THE SOUTHERN HALF OF THE FA). THIS RAINFALL WOULD OVER A COUPLE DAYS AND ANY FLOOD THREAT IS DEPENDENT ON WHAT OCCURS SATURDAY/SATURDAY NIGHT. MONDAY NIGHT-FRIDAY...12Z GFS/12Z ECMWF IN PRETTY GOOD AGREEMENT IN SHOWING THE 500 MB LOW OVER EASTERN SD/MN REGION TUESDAY THEN DRIFTING A BIT SOUTH AND EAST WEDNESDAY AND THEN EAST OF THE AREA THURSDAY. LOOK FOR A CONTINUED HIGH THREAT FOR SHOWERS TUESDAY...DIMINISHING ON WEDNESDAY. A 500 MB RIDGE WILL BUILD IN BEHIND THE LOW FOR THE END OF THE WEEK WITH DRY WEATHER RETURNING. LOOK FOR TEMPS TO BIT A BIT BELOW NORMAL WITH THE CLOUDS/RAIN TUE- WED THEN RETURN TO CLOSE TO NORMAL LEVELS BY LATE WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1243 PM CDT FRI MAY 17 2013 QUESTION FOR THIS PERIOD WILL BE HOW FAR NORTH THE MVFR CLOUDS SPREAD DURING THE NIGHT INTO SATURDAY MORNING AND PRECIPITATION (THUNDER) CHANCES. THRU 00Z FORSEE ALL SITES STAYING VFR..BUT WATCHING AN AREA OF HIGHER DEW POINTS ALONG WITH 25-35K FT CLOUD DECK MOVING SLOWLY NORTHWEST FROM WCNTRL MN AND ECNTRL SD. TIMING OF THIS MOVEMENT NORTHWEST INTO FARGO AREA IS SUSPECT...BUT LATEST RAP MODEL SUGGEST 03Z-06Z PERIOD. THESE CONDITIONS MAY REACH THE OTHER TAF SITES TOWARD 12Z. PRECIP (THUNDER) CHANCES LATER TONIGHT INTO SATURDAY MORNING AND WHEN/HOW IT AFFECTS ANY TAF SITE IS QUITE DIFFICULT TO DETERMINE NOW. FOR NOW JUST INCLUDED A TEMPO GROUP FOR FARGO AS BEST CHANCE APPEARS THERE OVERNIGHT. WINDS WILL REMAIN SOUTHEAST MOSTLY 10 TO 20 KTS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ SHORT TERM...TG LONG TERM...TG/RIDDLE AVIATION...RIDDLE
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1243 PM CDT FRI MAY 17 2013 .UPDATE... ISSUED AT 1243 PM CDT FRI MAY 17 2013 SCATTERED SHOWERS ACROSS THE NW FA WILL EXIT BY LATER THIS AFTERNOON AS ASSOCIATED UPPER WAVE PROPAGATES INTO CANADA. CLEAR SKIES REMAIN ACROSS PORTIONS OF THE SOUTHERN FA...AND TEMPERATURES WITHIN THIS AREA ARE NOW INTO THE 70S. THE TREND OF BECOMING CLOUDY STILL LOOKS GOOD...BUT IT WILL TAKE SOME TIME. INCREASED MAX TEMPS INTO THE MID-UPPER 70S WITHIN THE CLEAR AREA...AND SLOWED DOWN THE PROGRESSION OF THIS AREA BECOMING CLOUDY. THE OTHER ISSUE WILL BE THUNDER CHANCES TONIGHT. FOLLOWING THE LATEST RAP/HRRR GUIDANCE AND 12Z NAM/GFS...THERE WILL BE A SURGE OF INSTABILITY AS 850MB WINDS AND WARM AIR ADVECTION INCREASE (ALONG ELEVATED WARM FRONT). THIS WILL HAPPEN CLOSER TO 03Z-06Z ACROSS THE SOUTHERN FA. THE RAP INDICATES 850MB CAPE ABOVE 1000 J/KG ALONG WITH AROUND 35 KNOTS OF DEEP LAYER SHEAR...WHICH COULD POSSIBLY LEAD TO ISOLATED SEVERE HAIL (SEVERE HAIL POTENTIAL IS DEPENDENT ON STRENGTH OF INSTABILITY). THIS COMPLEX WILL LIKELY WEAKEN AS IT MOVES TO THE NORTH...BUT THUNDER/SHOWER CHANCES SHOULD HOLD TOGETHER AND EXIT THE NORTHERN FA SATURDAY MORNING. UPDATED THE GRIDS THROUGH TONIGHT FOR THIS THINKING (AND WILL CONCENTRATE ON SATURDAY THROUGH MONDAY FOR THE NEXT FORECAST ISSUANCE). && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 325 AM CDT FRI MAY 17 2013 FORECAST CHALLENGE CONCERNS PCPN CHANCES/AMOUNTS AND TEMPERATURES. MODELS IN GENERAL AGREEMENT WITH MAIN FEATURES HOWEVER ALL DIFFER ON QPF SCENARIOS THROUGH THE SHORT TERM. AT THIS POINT WILL USE A GENERAL BLEND. PERSISTENT BAND OF -SHRA ASSOCIATED WITH ELEVATED ZONE OF ENHANCED WARM ADVECTION AND H7 CONVERGENCE SHOULD GRADUALLY WEAKEN THROUGH THE MORNING AS ABOVE FEATURES WEAKEN AND SHIFT NE. WILL GO WITH HIGH POP/LOW QPF INTO MID MORNING THEN TRIM BACK ON POPS. ELSEWHERE CONFIDENCE LOW ON ANY PCPN POTENTIAL THROUGH THE BULK OF THE DAY. SURFACE LOW AND E-W ORIENTED WARM FRONTAL BOUNDARY ALONG SD/NE BORDER INTO IA LIFTS SLOWLY THROUGH SD DURING THE DAY. EXPECT MOST PCPN WILL BE ORIENTED CLOSER TO LOW LEVEL BOUNDARY TO OUR SOUTH. WILL INCREASE POPS SOMEWHAT LATER IN THE AFTERNOON AS BOUNDARY APPROACHES. TEMPERATURES WILL BE HIGHLY INFLUENCED BY CLOUDS. RAISED TEMPERATURES SLIGHTLY ACROSS THE SOUTH WHERE SOME THINNER CLOUD COVER EXISTS OTHERWISE WILL STICK WITH PERSISTENCE. AS WARM FRONT LIFTS NORTH TONIGHT EXPECT RAIN CHANCES TO INCREASE AND BY MID EVENING SOUTHERN AND WESTERN FORECAST AREAS LOOK TO BE FAVORED AREAS FOR SHRA/TSRA. BEST THUNDER POTENTIAL WILL BE ACROSS THE SOUTH AS NORTHERN AREAS STILL PRETTY STABLE. BAND OF PCPN SHOULD LIFT NORTHWARD OVERNIGHT NIGHT AND ADJUSTED POPS ACCORDINGLY. FRONTAL BOUNDARY WILL BE ORIENTED ACROSS FA SATURDAY SO INCREASED POPS. SEVERE POTENTIAL LOOKS BEST LATE IN THE AFTERNOON ACROSS THE SOUTH HALF OF THE FA WITH FAVORABLE CONVECTIVE PARAMETERS. .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 325 AM CDT FRI MAY 17 2013 SEVERE CONVECTIVE THREAT WILL CONTINUE INTO THE EVENING. WITH PRECIPITABLE H2O VALUES AROUND 1.5 INCHES HEAVY RAIN WILL BE A POSSIBILITY. INITIALLY FAVORED AREA FOR HEAVY RAIN LOOKS TO BE ACROSS S HALF OF FA LIFTING NORTHWARD DURING THE OVERNIGHT. WITH CUT OFF LOW DEVELOPING VCNTY OF FA POTENTIAL FOR SIGNIFICANT RAIN WILL CONTINUE THROUGH THE WEEKEND AND WILL NEED TO MONITOR RAIN AMOUNTS CLOSELY. AT THIS POINT LONG DURATION RAIN EVENT FOR SURE BUT NOT ENOUGH CONFIDENCE ON ANY PARTICULAR LOCATION FOR FLOOD/FLASH FLOOD WATCH. 0 UTC GFS/ECMWF/GEM IN GOOD OVERALL AGREEMENT NEXT WEEK...SHOWING A CLOSED 500 HPA LOW ACROSS SOUTHEAST SD MONDAY MORNING CRAWLING PAINFULLY SLOW TO THE EAST THROUGH WEDNESDAY. THIS FIRMLY ENTRENCHES THE FORECAST AREA IN WRAP-AROUND RAIN SHOWERS THROUGH TUESDAY... SLOWLY DRYING OUT WEDNESDAY AND A RETURN TO DRY CONDITIONS ON THURSDAY. WILL KEEP THUNDER MENTION THROUGH MONDAY...BUT MOST INSTABILITY SHOULD MOVE TO THE SOUTH BY TUESDAY. WITH CLOUD COVER AND RAIN... TEMPERATURES WILL BE NEAR OR SLIGHTLY BELOW MID-MAY NORMALS WITH HIGHS IN THE UPPER 50S AND 60S AND LOWS IN THE 40S/LOWER 50S. WITH GREATER SUNSHINE AND DRY CONDITIONS...SHOULD SEE SOME AREAS REACHING 70 DEGREES BY THURSDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1243 PM CDT FRI MAY 17 2013 QUESTION FOR THIS PERIOD WILL BE HOW FAR NORTH THE MVFR CLOUDS SPREAD DURING THE NIGHT INTO SATURDAY MORNING AND PRECIPITATION (THUNDER) CHANCES. THRU 00Z FORSEE ALL SITES STAYING VFR..BUT WATCHING AN AREA OF HIGHER DEW POINTS ALONG WITH 25-35K FT CLOUD DECK MOVING SLOWLY NORTHWEST FROM WCNTRL MN AND ECNTRL SD. TIMING OF THIS MOVEMENT NORTHWEST INTO FARGO AREA IS SUSPECT...BUT LATEST RAP MODEL SUGGEST 03Z-06Z PERIOD. THESE CONDITIONS MAY REACH THE OTHER TAF SITES TOWARD 12Z. PRECIP (THUNDER) CHANCES LATER TONIGHT INTO SATURDAY MORNING AND WHEN/HOW IT AFFECTS ANY TAF SITE IS QUITE DIFFICULT TO DETERMINE NOW. FOR NOW JUST INCLUDED A TEMPO GROUP FOR FARGO AS BEST CHANCE APPEARS THERE OVERNIGHT. WINDS WILL REMAIN SOUTHEAST MOSTLY 10 TO 20 KTS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...TG SHORT TERM...VOELKER LONG TERM...VOELKER/ROGERS AVIATION...RIDDLE
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
401 PM CDT FRI MAY 17 2013 .SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT THE MODELS ALL AGREE WELL AND CONTINUE TO BE VERY CONSISTENT AT BRINGING THE UPPER LEVEL LOW PRESSURE TROUGH OUT OF THE SOUTHWEST US THROUGH SUNDAY NIGHT AND CLOSING IT OFF. THUNDERSTORMS ARE BEGINNING TO DEVELOP IN WESTERN SOUTH DAKOTA LATE THIS AFTERNOON AND WILL CONTINUE TO DEVELOP AND MOVE EAST INTO CENTRAL AND NORTH CENTRAL SOUTH DAKOTA THROUGH THE EVENING. THE HRRR MODEL SHOWS THIS DEVELOPMENT VERY WELL. AS THE LLJ INCREASES INTO THE EVENING HOURS...EXPECT THIS TREND TO CONTINUE. WITH INSTABILITY INCREASING ALONG WITH DEEP LAYER SHEAR...SOME SEVERE STORMS ARE POSSIBLE MAINLY WEST OF THE JAMES VALLEY TONIGHT. THIS FIRST WAVE WILL MOVE THROUGH WITH MORE DEVELOPMENT EXPECTED SATURDAY AFTERNOON AND EVENING ACROSS THE CWA. HIGH INSTABILITY WILL BUILD UP AGAIN SATURDAY AFTERNOON AND EVENING ACROSS THE CWA WHILE ANOTHER SHORT WAVE TROUGH KICKS OUT OF THE SOUTHWEST UPPER TROUGH. THIS INTERACTION ALONG A GOOD LOW LEVEL SURFACE BOUNDARY/WARM FRONT ON SATURDAY AFTERNOON AND EVENING WILL RESULT IN NUMEROUS SHOWERS AND THUNDERSTORMS AGAIN. SEVERE STORMS LOOK LIKE A GOOD POSSIBILITY ON SATURDAY AFTERNOON AND EVENING. AS THE MAIN UPPER LEVEL TROUGH LIFTS INTO THE REGION SUNDAY AND SUNDAY NIGHT AND CLOSES OFF...SHOWER AND THUNDERSTORM POSSIBILITIES WILL CONTINUE TO BE VERY GOOD ACROSS ALL OF THE CWA. HEAVY RAIN WILL ALSO BE A THREAT ACROSS THE CWA AS HIGH PRECIPITABLE WATERS WILL BE AVAILABLE FOR STORMS. .LONG TERM...MONDAY THROUGH FRIDAY DECENT AGREEMENT EXISTS BETWEEN DETERMINISTIC GUIDANCE TO START THINGS OFF WITH A NEARLY STATIONARY UPPER LOW OVER THE EASTERN DAKOTAS/MINNESOTA. THIS FEATURE WILL DRIFT SLOWLY TO THE EAST...WITH WRAP AROUND MOISTURE AND WEAK INSTABILITY LEADING TO CONSTANT WIDESPREAD SHOWER ACTIVITY...WHICH WILL ALSO RESULT IN TEMPERATURES BELOW NORMAL FOR MUCH OF THE EXTENDED. ONCE THE UPPER LOW PUSHES EAST...A COL AREA FORMS OVERHEAD...WITH WEAK SOUTHEASTERLY LOW LEVEL RETURN FLOW DEVELOPING FOR THE END OF THE PERIOD...WITH MILDER TEMPERATURES AND LIKELY DRY CONDITIONS. && .AVIATION... 18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS VFR CONDITIONS FOR KABR/KMBG...WITH KATY/KPIR MIXING OUT MVFR CIGS BY THE EARLY AFTERNOON. A FEW WEAK SHOWERS COULD DEVELOPS AT KABR/KATY THIS AFTERNOON WITH NEGLIGIBLE EFFECT. MAIN THREAT WILL BE STORMS PUSHING INTO THE KPIR/KMBG TERMINALS DURING THE EVENING. THIS AREA OF CONVECTION WILL THEN POSSIBLY IMPACT KABR/KATY TERMINALS OVERNIGHT. THERE IS THE POSSIBILITY THAT CONVECTION WILL LEAVE US WITH MVFR CIGS BY THE MORNING...THOUGH WITH LOW FORECASTER CONFIDENCE. WINDS WILL BE OUT OF THE EAST/SOUTHEAST...BUT WILL INCREASE IN INTENSITY SOMEWHAT AS THEY SHIFT TO DUE SOUTH EARLY SATURDAY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ SHORT TERM...MOHR LONG TERM...CONNELLY AVIATION...CONNELLY WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1223 PM CDT FRI MAY 17 2013 .AVIATION... CONCERNS...RETURN OF MVFR CIGS LATE TONIGHT. CURRENT MVFR CIGS ACROSS THE METROPLEX SHOULD GO SCT030-040 FOR MOST TAF SITES EARLY THIS AFTERNOON WHILE KFTW/KAFW MAY REMAIN BKN030 THROUGH 20Z. AFTERWARD...VFR CONDITIONS WITH SOUTHERLY WINDS 13-20KTS. EXPECT ANOTHER ROUND OF STRATUS LATE TONIGHT 08-10Z THAT WILL PERSIST UNTIL 15Z. VFR SKIES LATE MORNING THROUGH LATE SATURDAY AFTERNOON. SURFACE WINDS SHOULD BE SEVERAL KNOTS HIGHER ON SATURDAY AFTERNOON THAN THIS AFTERNOON. AS FOR CONVECTION...MIDDAY CONVECTION BETWEEN KCRS-KLFK-KUTS WILL PERSIST SEVERAL MORE HOURS AS THE CELLS PROPAGATE SOUTHEAST. OTHERWISE...FORECAST SOUNDINGS SHOW ALL FWD TAF SITES REMAINING STRONGLY CAPPED THROUGH THE FORECAST PERIOD. HOWEVER...FAR TO THE WEST...A DRYLINE WILL NEAR A KCDS-KABI- KSJT LINE THIS AFTERNOON AND SHOULD BE ABLE TO PRODUCE SEVERAL SUPERCELL THUNDERSTORMS BETWEEN 21-23Z. NONE ARE EXPECTED TO AFFECT OUR TAF SITES. 75 && .UPDATE... 12Z FWD SOUNDING DEPICTS NEARLY DRY ADIABATIC LAPSE RATES FROM 850MB UP TO 500MB. CURRENTLY A WEAK SHORTWAVE WAS MOVING ACROSS NORTH TEXAS IN NORTHWEST FLOW ALOFT AND WAS RESPONSIBLE FOR THE ELEVATED CONVECTION OCCURRING OVER THE SOUTHEAST ZONES THIS MORNING. THESE STORMS HAVE PRODUCED HAIL UP TO GOLF BALL SIZE AND ARE A TESTAMENT TO THE STEEP LAPSE RATES ALOFT. THIS SHORTWAVE WILL CONTINUE TO MOVE SOUTHEAST AND OUT OF THE AREA BY MIDDAY. STRONG SURFACE HEATING ACROSS THE WESTERN ZONES WILL HELP PUSH TEMPERATURES TO NEAR THE CENTURY MARK THIS AFTERNOON. A DRY LINE WILL REACH A LINE FROM GRAHAM TO COMANCHE TO LLANO. SHORT TERM MODELS DEPICT DEWPOINTS IN THE LOW TO MID 70S AHEAD OF THE DRY LINE...BUT THIS IS PROBABLY TOO HIGH. BELIEVE DEWPOINTS WILL MIX OUT INTO THE UPPER 60S. NONETHELESS...THIS WILL CONTRIBUTE TO EXTREME INSTABILITY WITH SURFACE BASED CAPE VALUES ABOVE 4000 J/KG. UNLIKE THE EVENT ON WEDNESDAY...THE CAP WILL BE MUCH STRONGER TODAY AND WILL REQUIRE STRONG HEATING AND THE MESOSCALE FORCING PROVIDED BY A DRY LINE TO BE OVERCOME. GIVEN A REASONABLE FORECAST TEMP/DEWPOINT COMBINATION OF 99 OVER 68 AHEAD OF THE DRY LINE...THIS SHOULD BE SUFFICIENT FOR THE CAP TO BREAK. SEVERAL OF THE HI-RES CONVECTION ALLOWING MODELS AND THE LAST 2 RUNS OF THE NAM ARE SHOWING STORM INITIATION LATE THIS AFTERNOON...AND ARE FOCUSING IN ON THE AREA NEAR THE LLANO UPLIFT...WHICH WOULD AFFECT OUR SW ZONES AND ALSO ANOTHER AREA NEAR GRAHAM AND BRECKENRIDGE. DEEP LAYER SHEAR IS NOT OVERLY STRONG AND IS ON THE LOW END OF THE ALLOWABLE LEVEL FOR SUPERCELLS. HOWEVER THE HIGH INSTABILITY WILL LIKELY COMPENSATE AND ALLOW FOR SUPERCELL MODES. SUPERCELL STORM MOTION TECHNIQUES BASED ONLY ON WIND PROFILES ARE EAST AT 10KT...BUT IN CASES OF HIGH INSTABILITY AND WEAK FLOW...THESE SUPERCELLS WILL LIKELY HEAD SLOWLY SOUTHEAST OR EVEN DUE SOUTH. GIANT HAIL...PERHAPS GREATER THAN BASEBALLS WILL BE POSSIBLE WITH ANY SUPERCELL STORM. SURFACE TEMPS WILL LIKELY REACH 105 WEST OF OUR CWA BEHIND THE DRY LINE...WHICH SHOULD ALLOW A THERMAL SURFACE LOW TO INTENSIFY TODAY. THIS WILL CAUSE LOW LEVEL WINDS TO BACK OVER THE NORTHERN PART OF THE CWA...WHICH WILL ENHANCE LOW LEVEL DIRECTION SHEAR PROFILES ACROSS THE NORTHWEST CWA DESPITE WIND SPEEDS REMAINING FAIRLY WEAK AND LESS THAN 15KT AT ANY GIVEN LEVEL. STORM RELATIVE 0-3KM HELICITY VALUES BY THE RUC/NAM ARE FORECAST TO BE NEAR 100-150 MS/S2...SIGNIFICANTLY LESS THAN LAST WEDNESDAY...BUT AGAIN THE HIGHER INSTABILITY CAN OFTEN COMPENSATE TO RAISE THE CONCERN FOR TORNADOGENESIS. IN ADDITION SHOULD SUPERCELLS IN FACT MOVE SOUTH...THESE MODEL VALUES OF 0-3 SRH VALUES ARE TOO LOW. HAVE ADDED A RISK OF ISOLATED TORNADOES TO THE HWO AND GRAPHIC FORECASTS AS WELL. I SHOULD STRESS ALL OF THE SEVERE THREAT TODAY IS CONDITIONAL BASED ON THE CAP BREAKING...WHICH AGAIN IS NOT GUARANTEED BUT IS PROBABLE. WITH LESS HEATING ACROSS THE I-35 CORRIDOR...THIS SHOULD KEEP SEVERE CONVECTION CONFINED TO THE WESTERN ZONES WITH THE CAP TOO STRONG FOR SURFACE BASED CONVECTION IN THE CENTRAL AND EASTERN ZONES. STILL IT IS POSSIBLE RESIDUAL ELEVATED CONVECTION OR ANVIL PRECIPITATION MAY ENTER THE CENTRAL ZONES LATE TONIGHT...BUT WILL KEEP POPS AT 10 PERCENT WITH NO MODEL SUPPORT FOR THIS SCENARIO. FOR THE UPDATE HAVE LOWERED HIGHS IN THE SOUTHEAST ZONES DUE TO MORNING RAIN AND CLOUDS. HAVE RAISED POPS IN THE WESTERN ZONES TO REFLECT THE HIGHER POTENTIAL FOR STORMS THIS AFTERNOON AND EVENING. TR.92 && .PREV DISCUSSION... /ISSUED 354 AM CDT FRI MAY 17 2013/ ...A FEW SEVERE STORMS POSSIBLE ACROSS FAR WESTERN NORTH TEXAS BY EACH EVENING TODAY AND SATURDAY...THEN NORTH OF I-20 LATE SUNDAY... WEATHER FORECAST REMAINS CHALLENGING TODAY INTO THE WEEKEND. WE CONTINUED TO SEE A SUBTLE SURFACE BOUNDARY SITUATED ALONG/NORTH OF HWY 38 THIS MORNING AS EVIDENCED BY THE BACKED/LIGHTER EAST WINDS AND LOWER SURFACE DEW POINTS THIS MORNING...WHILE STRONGER SSE WINDS 10 TO 15 MPH WHERE OCCURRING FROM THE I-20 CORRIDOR INTO CENTRAL TEXAS. SOME PATCHY DENSE FOG WAS OCCURRING ALONG THE RED RIVER VALLEY...WHILE A SUBTLE DISTURBANCE WAS MOVING ACROSS WITHIN THE UPPER RIDGE OVER THE TOP OF THE AREA. SOME AC/ACCAS WAS NOTED ON INFRARED SATELLITE IMAGERY WITH STEEP LAPSE RATES ALOFT ON THE 00Z FWD SOUNDING AND MODELS. ISOLATED...ELEVATED/HIGH-BASED SHOWERS AND STORMS ARE POSSIBLE THIS MORNING MAINLY ALONG AND SOUTH OF THE I-20/I-30 CORRIDORS. LIGHTNING WILL BE THE MAIN THREAT WITH ACTIVITY THIS MORNING WITH VERY LITTLE IN THE WAY OF MEASURABLE RAINFALL EXPECTED. THE SURFACE DRYLINE AND ASSOCIATED LOW PRESSURE OVER FAR WEST TEXAS WILL CONTINUE TO DEEPEN AND SLIDE SLOWLY EAST TOWARD OUR FAR W/SW COUNTIES LATE THIS AFTERNOON/EVE. STRONG MIXING AND HEATING ALONG AND JUST AHEAD OF THIS FEATURE WILL HELP HIGHS SOAR WELL INTO THE 90S WITH A FEW AREAS TOPPING THE CENTURY MARK WEST OF I-35/I-35W. OUR CAPPING INVERSION WAS ELEVATED AND BASED ABOVE 800MB AND NOT OVERLY STOUT...SO DESPITE THE UPPER RIDGE ARRIVING OVERHEAD...FEEL THE HOT TEMPS WILL MAKE IT BREAKABLE. HIGH-RES WRF/ARW/AND HRRR MODELS ALL HINT AT ISOLATED STORM DEVELOPMENT JUST W/SW OF OUR CWA AT PEAK HEATING AND POTENTIALLY AFFECTING OUR FAR WSW COUNTIES BETWEEN 4 PM AND SUNSET. INSTABILITY WILL BE VERY HIGH WITH MODELS SHOWING 3500-5000 J/KG SBCAPE OR POSSIBLY MORE WITH VERY STEEP MID LEVEL LAPSE RATES OVER 8 DEG C/KM. ANY ISOLATED STORMS THAT OCCUR WILL LIKELY BE SEVERE WITH VERY LARGE HAIL AND DAMAGING DOWNBURSTS. DESPITE SURFACE DEW POINTS BEING NEAR 70 DEGREES...THE HOT TEMPERATURES WILL RESULT IN RELATIVELY HIGH BASES AND A LOWER TORNADO THREAT THAN A FEW DAYS AGO. WITH THE UPPER RIDGE OVERHEAD...STORMS WILL DIMINISH IN STRENGTH OR DISSIPATE RAPIDLY AROUND SUNSET WITH LOSS OF HEATING AND THE CAP INTENSIFYING QUICKLY BY LATE EVENING. THE UPPER RIDGE SHIFTS EAST OF THE AREA ON SATURDAY WITH LONGWAVE UPPER TROUGH SNAKING OVER THE ROCKIES INTO THE WESTERN HIGH PLAINS. THE DRYLINE WILL ACTUALLY MAKE A STRONGER PUSH TOWARD OUR FAR WESTERN COUNTIES BY EARLY EVENING SATURDAY WITH A LITTLE BETTER UPPER SUPPORT. INSTABILITY WILL BE VERY STRONG ONCE AGAIN WITH ISOLATED TO SCATTERED STRONG TO SEVERE STORMS EXPECTED MAINLY ALONG AND WEST OF HWY 281...THEN DIMINISHING QUICKLY AFTER SUNSET WITH THE CAP INTENSIFYING ONCE AGAIN. THE UPPER TROUGH DAMPENS OVER THE CONUS ON SUNDAY WITH STRONG WESTERLY FLOW ALOFT OCCURRING FROM THE RED RIVER VALLEY NORTH THROUGH THE CENTRAL PLAINS. HAVE MODIFIED BEST CHANCES TO OCCUR NORTH OF I-20 AND INTO THE RED RIVER VALLEY...WITH THE CAP BEING MUCH STRONGER OVER THE SOUTH. DIURNAL SEVERE WEATHER WILL BE POSSIBLE AGAIN...BUT CONFIDENCE IS LOWER FOR LATE SUNDAY DUE TO UNCERTAINTIES REGARDING CAP STRENGTH AND SOUTHERN EXTENT OF FORCING. THE BEST SURFACE FOCUS WILL BE ALONG A COLD FRONT THAT IS EXPECTED TO BE WELL TO THE NORTHWEST OF THE AREA AS WELL. OTHERWISE IN THE EXTENDED...STAYED WITH PERSISTENCE WITH THE PREVIOUS FORECAST WITH LOW POPS RETURNING BY MID WEEK WITH A COLD FRONT WEAKENING AND STALLING ACROSS THE NORTHWEST COUNTIES. A SHORTWAVE TROUGH WILL BE MOVING OVER THE CENTRAL AND SOUTHERN PLAINS AT THIS TIME AS WELL. IT IS TOO EARLY TO ASSESS ANY SEVERE WEATHER THREAT THIS FAR OUT...BUT WILL CONTINUE TO ASSESS THESE POSSIBILITIES IN THE COMING DAYS AHEAD. 05/ && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 89 72 93 72 88 / 10 10 5 10 10 WACO, TX 91 71 92 71 90 / 10 10 5 10 10 PARIS, TX 82 68 86 69 86 / 10 10 10 10 10 DENTON, TX 86 70 93 71 89 / 10 10 10 10 20 MCKINNEY, TX 84 69 91 69 88 / 10 10 5 10 10 DALLAS, TX 88 72 93 72 90 / 10 10 5 10 10 TERRELL, TX 87 69 90 70 89 / 10 10 5 10 10 CORSICANA, TX 89 70 91 70 89 / 40 10 5 10 10 TEMPLE, TX 91 70 91 71 89 / 10 20 10 10 10 MINERAL WELLS, TX 94 70 96 70 93 / 10 20 10 20 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 75/
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
341 PM CDT FRI MAY 17 2013 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 341 PM CDT FRI MAY 17 2013 LATEST SURFACE OBSERVATIONS PLACED A WARM FRONT EXTENDING FROM BOOKINGS SOUTH DAKOTA...EXTENDING SOUTHEAST THROUGH SOUTHERN MINNESOTA...TO NEAR FAIRMONT MINNESOTA...INTO EAST CENTRAL IOWA. THE FRONT WAS NEARLY STATIONARY THIS AFTERNOON BUT WILL START TO SLOWLY ADVANCE NORTHWARD TONIGHT. WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED AN ACTIVE PATTERN ACROSS THE CONUS. A VIGOROUS TROUGH WAS DIVING INTO THE CENTRAL ROCKIES...PUSHING EAST. A SHORTWAVE WAS MOVING ACROSS SOUTHERN MINNESOTA/NORTHERN THROUGH SOUTHERN WISCONSIN AND WAS GENERATING A PERSISTENT BAND OF SHOWERS AND ISOLATED THUNDERSTORMS. HEAVY RAIN HAS FALLEN ACROSS PORTIONS OF NORTH CENTRAL IOWA INTO SOUTHEAST MINNESOTA. KEEPING A VERY CLOSE WATCH ON THE WARM FRONT LATE THIS AFTERNOON INTO THIS EVENING WITH ADDITIONAL SHOWER AND THUNDERSTORM DEVELOPMENT EXPECTED ALONG IT. A CONVERGENT AREA WAS NOTED IN THE SURFACE WINDS FIELDS OVER SOUTHWEST MINNESOTA...AND SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ACROSS THESE AREAS. ALL OF THE MESOSCALE MODEL GUIDANCE IS SUGGESTING THAT THIS AREA OF SHOWERS AND STORMS WILL CONTINUE AND DRIFT SOUTHEAST ALONG THE FRONT LATE THIS AFTERNOON INTO THIS EVENING. A VERY UNSTABLE AIRMASS IS FEEDING INTO THE WARM FRONT. WHERE THERE HAS BEEN SUN THIS AFTERNOON...SURFACE BASES CAPE VALUES HAVE CLIMBED TO AROUND 2000 J/KG. A RATHER MOIST AIRMASS IN PLACE OVER THE AREA WITH PRECIPITABLE WATER VALUES OF 1.2 TO 1.3 INCHES. THE SHOWERS AND THUNDERSTORMS HAVE BEEN VERY EFFICIENT RAIN PRODUCERS TODAY AND WITH THIS MOIST AIRMASS IN PLACE...ANY ADDITIONAL SHOWERS AND STORMS WOULD ALSO BE EFFICIENT RAIN PRODUCERS. 0-6 KM SHEAR IS RATHER WEAK SO THINKING THE MAIN SEVERE WEATHER THREAT WITH ANY THUNDERSTORMS TONIGHT WOULD BE PERIODS OF HEAVY RAINFALL. CANNOT RULE OUT AN ISOLATED STORM OR TWO WITH LARGE HAIL. THE MAIN CONCERN FOR THIS ACTIVITY IS ACROSS PORTIONS OF SOUTHEAST MINNESOTA INTO NORTHEAST IOWA. A THUNDERSTORM COMPLEX WILL FIRE OVER WESTERN SOUTH DAKOTA AND RACE EAST TONIGHT. INSTABILITY REALLY WANES LATE THIS EVENING...WITH 0-3 KM MUCAPE VALUES FALLING TO 300 J/KG ACROSS SOUTHEAST MINNESOTA AND NORTHEAST IOWA MAINLY AFTER 6Z TONIGHT. THINKING THE THUNDERSTORMS WILL REALLY START TO DIE OFF WHEN THEY APPROACH THE INTERSTATE 35 CORRIDOR. THE STRONGEST 850 MB MOISTURE TRANSPORT STAYS FOCUSED INTO EASTERN SOUTH DAKOTA THROUGH THE LATE NIGHT HOURS SO A WEAKENING TREND SEEMS REASONABLE AND THE MESOSCALE MODELS ARE ALSO IN LINE WITH THIS. EARLY SATURDAY MORNING...THE WARM FRONT IS EXPECTED TO SLOWLY LIFT NORTH OF THE INTERSTATE 90 CORRIDOR. CLOUD COVER OVER CENTRAL AND NORTHERN WISCONSIN MAY SLOW ITS ADVANCE TO THE NORTH WITH THE COOLER AIR UNDER CLOUD COVER TO THE NORTH AND SOME SUNSHINE SOUTH OF THE WARM FRONT. FORECAST MODELS HAVE BEEN GENERATING SOME LIGHT PRECIPITATION ACROSS AREAS RIGHT ALONG AND EAST OF THE MISSISSIPPI RIVER LATE SATURDAY MORNING INTO SATURDAY AFTERNOON. THERE REALLY ISN/T ANY APPRECIABLE FORCING ALOFT TO WORK WITH BUT FORECAST SOUNDINGS SHOW CAPE VALUES INCREASING TO AROUND 1500 J/KG ACROSS PORTIONS OF SOUTHEAST MINNESOTA AND TO AROUND 300 J/KG OVER NORTH CENTRAL WISCONSIN. HAVE EXTENDED SHOWER/THUNDERSTORM CHANCES A BIT FURTHER SOUTH OVER THE PREVIOUS FORECAST TO ACCOUNT FOR THE INSTABILITY AND SLOWER MOVEMENT OF THE WARM FRONT. IT WILL BE RATHER WARM ON SATURDAY IN THE WAKE OF THE WARM FRONT WITH HIGHS CLIMBING INTO THE LOWER TO MID 80S OVER NORTHEAST IOWA...SOUTHEAST MINNESOTA AND FAR WESTERN WISCONSIN. IT WILL BE A LITTLE COOLER ACROSS NORTH CENTRAL WISCONSIN WHERE HIGHS WILL STRUGGLE TO GET OUT OF THE LOWER 70S. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 341 PM CDT FRI MAY 17 2013 A VERY ACTIVE PATTERN IS IN STORE FOR THE REGION SUNDAY THROUGH MONDAY WITH SEVERE WEATHER POSSIBLE. THUNDERSTORMS FIRING OVER THE DAKOTAS INTO THE CENTRAL PLAINS AND MOVING EAST INTO THE FORECAST AREA SUNDAY MORNING WILL HAVE AN IMPACT ON CONVECTION FOR SUNDAY AFTERNOON. A POTENT SHORTWAVE EJECTS OUT OF THE CENTRAL PLAINS SUNDAY AFTERNOON AND LIFTS NORTH INTO THE UPPER MISSISSIPPI RIVER VALLEY...BECOMING NEGATIVELY TILTED. MEANWHILE...SURFACE LOW PRESSURE DEEPENS OVER SOUTHEAST SOUTH DAKOTA...AND A SECONDARY WARM FRONT DEVELOPS OVER NORTHERN IOWA AND LIFTS NORTH INTO SOUTHERN MINNESOTA EARLY SUNDAY EVENING. 0-3KM MUCAPE VALUES INCREASE TO 1200-1500 J/KG LATE SUNDAY AFTERNOON ACROSS NORTHERN IOWA/SOUTHERN MINNESOTA AND SOUTHWEST WISCONSIN. 0-6 KM SHEAR INCREASES AS THE WAVE MOVES INTO THE AREA...INCREASING TO 30 TO 45 KTS LATE SUNDAY AFTERNOON INTO SUNDAY EVENING. MOST OF THIS SHEAR IS LOCATED IN THE 0-3 KM LAYER...OVERALL RATHER IMPRESSIVE LOW LEVEL SHEAR PROFILES. LATEST THINKING IS THAT THUNDERSTORMS WILL ERUPT OVER PORTIONS OF WESTERN IOWA SUNDAY AFTERNOON WITH ADDITIONAL DEVELOP POSSIBLE TO THE NORTHEAST ACROSS SOUTHEAST MINNESOTA AND NORTHEAST IOWA....AND POTENTIALLY INTO SOUTHWEST WISCONSIN. SHEAR PROFILES WOULD FAVOR SUPERCELL STRUCTURES. SINCE MOST OF THE SHEAR IS LOCATED IN THE 0-3 KM LAYER...THERE IS GROWING CONCERN FOR DAMAGING WINDS AND BOWING STRUCTURES WITH THE STORMS. ISOLATED TORNADOES ARE ALSO POSSIBLE. ALSO...THERE IS THE POTENTIAL FOR HEAVY RAINFALL...ESPECIALLY SUNDAY EVENING AS 850 MB MOISTURE TRANSPORT INCREASES ACROSS NORTHERN IOWA/SOUTHERN MINNESOTA AND SOUTHWEST WISCONSIN...FOCUSING INTO THE WARM FRONT. A BROAD UPPER TROUGH OVER THE UPPER MIDWEST WILL FINALLY CLOSE INTO AN UPPER LOW ON MONDAY. SEVERAL PIECES OF ENERGY ROTATING AROUND THE LOW WILL BRING ADDITIONAL CHANCE FOR SHOWERS AND THUNDERSTORMS TO THE AREA. THINKING THE BULK OF THE INSTABILITY SHOULD BE SOUTHEAST OF THE FORECAST AREA SO IT APPEARS THE GREATEST SEVERE THREAT SHOULD BE SOUTHEAST OF THE AREA...BUT THIS WILL DEPEND ON HOW THE CONVECTION PLAYS OUT SUNDAY NIGHT. THE UPPER LOW CONTINUES TO SPIN OVER THE REIGON THROUGH MIDWEEK WITH DAILY CHANCES FOR SHOWERS AND POSSIBLE THUNDERSTORMS. && .AVIATION...TODAY AND TONIGHT 1130 AM CDT FRI MAY 17 2013 SFC FRONT LAYING WEST-EAST ACROSS SOUTHERN MN/WESTERN WI CONTINUES TO BE A FOCUS FOR SHRA/ISOLD TS DEVELOPMENT LATE THIS MORNING. NOT MUCH-IF ANY INSTABILITY OR LOW LEVEL MOISTURE TRANSPORT INTO THE FRONT THOUGH...PER MESO MODELS. INDICATIONS THAT THE PCPN IS GETTING SOME ENHANCEMENT ON ITS WESTERN EDGES FROM AN UPPER LEVEL SHORTWAVE TROUGH...PER LATEST WATER VAPOR SATELLITE IMAGERY. THIS FEATURE IS MOVING EAST...AND NAM12/HRRR SUGGEST THAT THE PCPN WILL MOVE WITH IT. WILL TREND THE TAFS THIS WAY. THE HRRR DOES HINT THAT THE FRONT WON/T MOVE TOO FAR NORTH THIS EVENING...AND COULD SERVE AS A FOCUS FOR MORE SCT SHRA/TS. ARXLAPS ALSO HAS THIS POTENTIAL...WEST OF THE MISSISSIPPI RIVER. CONFIDENCE SHAKY ON THIS POSSIBILITY...AND WILL LIKELY LEAVE OUT OF THE KRST TAF FOR NOW. WITH THE PROLONGED PERIOD OF RAIN MOISTENING THE BOUNDARY LAYER FOR KRST/KLSE...FOG/STRATUS BECOMES A CONCERN OVERNIGHT. KLSE LIKELY DECOUPLES RESULTING IN LIGHT/VRB WINDS. KRST PROBABLY STICKS AROUND 6-8KTS FROM THE ESE. NUMERICAL GUIDANCE AND BUFKIT SOUNDINGS POINT TO GOOD SATURATION UNDER THE NOCTURNAL INVERSION THAT VSBY RESTRICTIONS ARE LIKELY...ALONG WITH LOW STRATUS. MVFR/IFR CONDITIONS ARE FAVORED INTO SATURDAY MORNING. && .HYDROLOGY...THIS EVENING THROUGH MONDAY ISSUED AT 341 PM CDT FRI MAY 17 2013 PERIODS OF SHOWERS AND THUNDERSTORMS ACROSS PORTIONS OF SOUTHEAST MINNESOTA INTO NORTHEAST IOWA HAVE PRODUCED 2 TO NEARLY 2 1/2 INCHES OF RAINFALL SO FAR TODAY. SCATTERED THUNDERSTORMS ARE EXPECTED LATE THIS AFTERNOON INTO EARLY THIS EVENING. THE STORMS ARE SLOW MOVING AND WILL HAVE THE POTENTIAL TO PRODUCE PERIODS OF HEAVY RAINFALL...WHICH COULD LEAD TO FLOODING...ESPECIALLY ACROSS THOSE AREAS THAT HAVE ALREADY SEEN HEAVY RAINFALL. THUNDERSTORMS ARE EXPECTED SUNDAY AFTERNOON THROUGH MONDAY. THE STORMS COULD PRODUCE PERIODS OF HEAVY RAINFALL WHICH COULD LEAD TO FLOODING. 1 TO 3 INCHES OF ADDITIOANL RAINFALL IS POSSIBLE FROM SUNDAY INTO WEDNESDAY. A FLASH FLOOD WATCH MAY BE NEEDED IF CONFIDENCE INCREASES ON WHERE THE HEAVIEST RAIN WILL FALL. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION.....RIECK HYDROLOGY...WETENKAMP
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1234 PM CDT FRI MAY 17 2013 UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE .SHORT TERM...TODAY...TONIGHT...AND SATURDAY ISSUED AT 346 AM CDT FRI MAY 17 2013 FORECAST CONCERNS THIS PERIOD ON PCPN CHANCES THROUGH THE PERIOD. WARM FRONT EXTENDS EAST OUT OF NE INTO NORTHERN IL. ONGOING PCPN OVER IA/MN BORDER...NOW EDGING INTO WESTERN WI. CLOUDS HAVE KEPT TEMPS UP OVERNIGHT OVER MUCH OF CWA...WITH ONLY THE FAR NORTH FALLING INTO THE UPPER 30S. EASTERLY WINDS OVER WI...STILL USHERING IN DRY AIR WITH DEW POINTS IN THE 30S. THIS HAS SLOWED ADVANCE OF PCPN...THOUGH HIGH BASED...THE RETURNS ARE INCREASING OVER THE STATE. HAVE CONTINUED TREND OF EVENING FORECASTER TO SHIFT PCPN SOUTH INTO CENTRAL AND EAST CENTRAL WI LATER THIS MORNING...THEN SHIFT NORTH TONIGHT AND SAT AS WARM FRONT LIFTS NORTH/RIDGE BUILDS IN. HAVE TRENDED TOWARDS MESO MODELS LIKE HRRR FOR DAY 1 PCPN TRENDS. PCPN FOCUS ASSOCIATED WITH INCREASING ISENTROPIC LIFT/FGEN FORCING WITH 850 BAROCLINIC ZONE OVER STATE. HAVE STAYED WITH JUST SHOWER MENTION THROUGH TODAY AS INSTABILITY MISSING OVER EASTERN WI...BRINGING IN SLIGHT CHANCE LATER TONIGHT AND SATURDAY AS LOW LEVEL MOISTURE INCREASES AND STEEPER MID LEVEL LAPSE RATES SHIFT EAST. TEMPS TODAY TO BE HELD BACK BY CLOUDS AND EAST FLOW THUS STAYED WITH UPPER 50S AND LOWER 60S THROUGHOUT CWA. MAX TEMPS BACK TO NORMAL OR ABOVE ON SAT...EXCEPT EAST WITH CONTINUED EASTERLY COMPONENT. .LONG TERM...SATURDAY NIGHT THROUGH THURSDAY ISSUED AT 346 AM CDT FRI MAY 17 2013 THE MAIN CONCERN DURING THE LONG TERM IS TIMING PRECIPITATION INTO THE AREA. A FRONTAL BOUNDARY IS FORECAST TO PUSH NORTHEAST THROUGH WISCONSIN EARLY NEXT WEEK. SURFACE FLOW WILL BE OFF LAKE MICHIGAN BETWEEN HIGH PRESSURE TO THE EAST AND THE FRONT...BUT PRECIPITATION WILL MOVE IN AS THE FRONT PASSES AND THE SURFACE LOW TO THE WEST GETS CLOSER TO WISCONSIN. HAVE A DRY FORECAST FOR SATURDAY NIGHT BUT WENT WITH CHANCE POPS FOR CENTRAL AND NORTH CENTRAL WISCONSIN SUNDAY. HAVE AT LEAST A CHANCE OF SHOWERS AND THUNDERSTORMS GOING THROUGH THE MIDDLE OF NEXT WEEK AS THE SURFACE LOW AND UPPER LEVEL CYCLONE PASS TO THE EAST OF THE AREA. TEMPERATURES SHOULD REMAIN ABOVE NORMAL THROUGH THE EARLY PART OF NEXT WEEK BEFORE A SURFACE RIDGE MOVES INTO THE REGION BRINGING COOLER THAN NORMAL TEMPERATURES FOR THE LATTER HALF OF THE WEEK. && .AVIATION...FOR 18Z TAF ISSUANCE ISSUED AT 1230 PM CDT FRI MAY 17 2013 WARM FRONT TO THE SOUTH OF THE STATE WILL CONTINUE TO TRIGGER SHOWERS FOR THE REST OF THE AFTERNOON INTO TONIGHT...AND POSSIBLY SATURDAY MORNING ACROSS THE NORTH. DO NOT SEE THE WARM FRONT PUSHING NORTH TO FAST TONIGHT...SO LINGERING SHOWERS WILL GRADUALLY SHIFT TO THE NORTH OR OTHER SHOWERS AND STORMS THAT DEVELOP ACROSS MINNESOTA MOVE EAST INTO THE AREA. VFR CIGS WILL GIVE WAY TO MVFR AND POSSIBLY IFR CIGS LATER TONIGHT INTO EARLY SATURDAY MORNING. ISOLATED THUNDERSTORMS ARE POSSIBLE TONIGHT. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....TE LONG TERM......MG AVIATION.......ECKBERG
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1130 AM CDT FRI MAY 17 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 350 AM CDT FRI MAY 17 2013 FOCUS IS ON TRENDING CURRENT SHOWERS/STORMS ACROSS IA/MN...AND CONVECTIVE PROBABILITIES LATER TODAY ALONG WARM FRONT. LATEST RADAR SHOWS COMPLEX OF SHOWERS/STORMS ACROSS NORTHERN IA/SOUTHERN MN...WHICH IS FEEDING OFF 850 MB LOW-LEVEL JET...INTERACTING WITH A WARM FRONTAL BOUNDARY THAT STRETCHES ACROSS NORTHERN IOWA. THESE STORMS ARE EFFICIENT HEAVY RAIN PRODUCERS...GIVEN SLOW EASTWARD PROGRESS AND PWATS 1.4 TO 1.6 INCHES...WHICH IS 150 TO 180 PERCENT ABOVE NORMAL. THESE STORMS ARE EXPECTED TO MOVE EASTWARD ACROSS SOUTHEAST MINNESOTA AND EXTREME NORTHEAST IOWA...AND PARTS OF WESTERN WISCONSIN THROUGH MID/LATE MORNING. SOME OF THE STRONGER CELLS COULD PRODUCE SMALL HAIL...BUT NOT EXPECTING ANYTHING TO REACH SEVERE LIMITS. THE BIGGER IMPACT WOULD BE LOCALIZED HEAVY RAINFALL...AND IN TOTAL...AMOUNTS BETWEEN 1 AND 2 INCHES ARE POSSIBLE. THE BIG QUESTION FOR TODAY IS WHERE THE WARM FRONT ENDS UP...AND IF ANOTHER ROUND OF SHOWERS/STORMS DEVELOPS ALONG IT THIS AFTERNOON. LATEST RAP HAS A DECENT HANDLE RIGHT NOW...SHOWING THAT THE WARM FRONT SETTLES ALONG THE IA/MN BORDER...AND INTO SOUTHWEST WISCONSIN THIS AFTERNOON. ONGOING CONVECTION SHOULD KEEP NORTHWARD PROGRESS OF THE BOUNDARY LIMITED SO RAP SOLUTION SEEMS REASONABLE. THE REMNANTS OF THIS MORNING/S STORMS WOULD LIFT TO THE EAST/NORTHEAST...BUT LEFTOVER OUTFLOW BOUNDARIES COMBINED WITH MODEST DAYTIME HEATING AND A PASSING UPPER LEVEL SHORTWAVE LOOKS TO BE SUFFICIENT FOR ADDITIONAL SHOWERS AND STORMS TO DEVELOP. THESE SHOWERS AGAIN WOULD HAVE THE POTENTIAL TO PRODUCE HEAVY RAIN. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 350 AM CDT FRI MAY 17 2013 ...SEVERE WEATHER EVENT POSSIBLE SUNDAY AND AGAIN ON MONDAY... SATURDAY FEATURES UPPER LEVEL RIDGING ACROSS THE CENTRAL PLAINS AS THE WEST COAST TROUGH CONTINUES TO MOVE EASTWARD. AT THE SURFACE...LOW PRESSURE DEVELOPS IN THE LEE OF THE ROCKIES AND PUSHES THE AFOREMENTIONED WARM FRONT WELL NORTH OF THE FORECAST AREA. THE ATMOSPHERE BECOMES CAPPED FOR THE DAY...WITH THE WARM NOSE LAYER EVIDENT IN THE 850 TO 750 MB LAYER. PLENTY OF ELEVATED CAPE NOTED ACROSS THE AREA...ANYWHERE FROM 2000 TO 3000 J/KG BY SATURDAY AFTERNOON. THE CAP REMAINS IN PLACE DURING THE DAY...BUT DOES WEAKEN SOME BY LATE AFTERNOON AND EVENING AS CIN VALUES DROP TO LESS THAN 50 J/KG...MAINLY ALONG AND NORTH OF I-90. THE LACK OF A STRONG FORCING MECHANISM SHOULD KEEP CONVECTIVE INITIATION PROBABILITIES LOW...AND THIS IS WELL AGREED AMONG THE VARIOUS DETERMINISTIC MODELS. THE ONLY EXCEPTION IS IN THE 17.00Z GFS WHERE A WEAK UPPER LEVEL SHORTWAVE TROUGHS RIDES THE RIDGE ACROSS NORTHERN WISCONSIN. THIS COULD PROVIDE ENOUGH UPPER LEVEL SUPPORT TO BREAK THE WEAKER CAP AND ALLOW SHOWERS/STORMS TO INITIATE. HAVE CONTINUED CHANCE POPS MAINLY NORTH OF I-90 TO HIGHLIGHT THIS IDEA. ANY STORM CAPABLE OF BREAKING THROUGH THE CAP AND BECOMING SURFACE BASED HAS THE POTENTIAL TO PRODUCE LARGE HAIL AND POSSIBLY DAMAGING WINDS GIVEN THE INSTABILITY AND 0-6 KM BULK SHEAR NEAR 30 KTS. OTHERWISE...WARM DAY ON TAP WITH HIGHS IN THE LOW TO MID 80S. FOCUS TURNS TO THE POTENTIAL SEVERE WEATHER EVENT FOR SUNDAY AS THE AFOREMENTIONED UPPER LEVEL TROUGH BECOMES INCREASINGLY NEGATIVE TILTED AND EJECTS INTO THE CENTRAL PLAINS BY 12Z SUNDAY. THE BASE OF THE TROUGH WILL LIKELY BE ACROSS OK/KS...BUT QUICKLY LIFTS NORTHEAST TOWARD WESTERN IOWA BY 00Z MONDAY. AT THE SURFACE...LOW PRESSURE LOOKS TO MOVE NORTHEASTWARD FROM NEBRASKA TO NEAR SIOUX FALLS SD...AND A WARM FRONT SHOULD BE DRAPED ACROSS SOUTHWEST MINNESOTA EAST/SOUTHEASTWARD INTO NORTHEAST IOWA. IT/S POSSIBLE THERE COULD BE SOME DECAYING CONVECTION SUNDAY MORNING ACROSS WESTERN IOWA...AND THIS COULD PLAY INTO HOW UNSTABLE THE ATMOSPHERE BECOMES LATER THAT DAY ACROSS THE REGION. IN ANY RATE...MUCAPE VALUES ARE EXPECTED TO RANGE 3000 TO 3500 J/KG AND 0-6 KM BULK SHEAR VALUES APPROACH 35 KTS WEST OF THE MISSISSIPPI RIVER SUNDAY AFTERNOON AND EVENING. THE MAJORITY OF THE SHEAR IS FOUND IN THE 0-3 KM LAYER WITH 25 KTS SEEN. EVEN MORE EXCITING ARE THE 0-1 KM SHEAR PARAMETERS...WHICH IS AT LEAST 20 KTS. FINALLY...THE AIRMASS ACROSS SOUTHEAST MINNESOTA AND NORTHERN IOWA SUNDAY LOOKS TO BE SOMEWHAT JUICY WITH DEWPOINTS IN THE 60S. HOW JUICY IS STILL A QUESTION GIVEN DETERMINISTIC MODELS POOR HANDLING OF DEWPOINTS LATELY. 17.00Z NAM/GFS PUT UPPER 60S TO EVEN NEAR 70F BY 21Z SUNDAY...WHICH SEEMS A BIT OVERDONE. ADJUSTING SOUNDINGS TO WHAT COULD BE A MORE REALISTIC VALUE /LOW TO MID 60S/ BASED ON THE MOIST BIAS STILL YIELDS CAPE VALUES IN THE 1500 TO 2500 J/KG RANGE. IN SHORT...ENVISION STORMS TO FIRE UP ACROSS CENTRAL IOWA INTO SOUTHERN MINNESOTA BY EARLY AFTERNOON SUNDAY...THEN QUICK MOVE EAST/NORTHEAST...LASTING INTO THE EVENING HOURS. THE HIGHER SEVERE CHANCES ARE WEST OF THE MISSISSIPPI RIVER...AS STORMS WOULD WEAKEN SOME MOVING INTO WISCONSIN BUT STILL COULD REMAIN SEVERE. ORGANIZED DISCRETE STRONG/SEVERE STORMS WOULD BE THE PRIMARY MODE...MAINLY SUPERCELLS...WITH A PREFERENCE TO THE RIGHT MOVERS GIVEN CLOCKWISE CURVATURE SEEN IN THE HODOGRAPHS. THE MAIN THREATS LOOK TO BE VERY LARGE HAIL AND DAMAGING WINDS BUT ALSO A FAVORABLE ENVIRONMENT FOR TORNADOES GIVEN 0-1 KM BULK SHEAR /AT LEAST 20 KTS/ AND EHI /1.0 TO 3.0/. WILL HIGHLIGHT INCREASED THREAT ACROSS THE MANY PUBLIC PRODUCTS /HWO...GRAPHICAST...NEWS STORY/. THOSE WITH PLANS SUNDAY AFTERNOON/EVENING WILL NEED TO KEEP A VERY CLOSE EYE TO THE FORECAST. ANOTHER ROUND OF STRONG/SEVERE STORMS IS POSSIBLE MONDAY EVENING AS THE WHOLE SYSTEM SLOWLY EDGES EASTWARD. ANOTHER FAVORABLE SEVERE WEATHER ENVIRONMENT WITH 0-6 KM MUCAPE PEGGED BETWEEN 2000 TO 3000 J/KG AND BULK SHEAR 30 TO 40 KTS. DEPENDING ON HOW MUCH EASTWARD PROGRESSION OF THE WEATHER SYSTEM OCCURS MONDAY...A GREATER PERCENTAGE OF THE FORECAST AREA COULD BE IN RISK FOR SEVERE WEATHER. AT THIS TIME...HIGHER THREAT AREA LOOKS TO BE ALONG AND SOUTH OF I-90. MODEL TIMING DIFFERENCES CREEP UP BY TUESDAY...MAINLY IN HOW QUICKLY THE UPPER LEVEL CLOSES OFF AND MOVES EAST OVER THE AREA. WIDE RANGE OF POSSIBILITIES ON WHEN THE LOW MOVES OVERHEAD...WITH THE 17.00Z GFS THE QUICKEST /TUESDAY/ AND THE ECMWF SLOWEST /WEDNESDAY/. FOR NOW...PERIODIC SHOWERS/STORMS TUESDAY AND WEDNESDAY LOOK GOOD. COOLER TEMPERATURES ALOFT AND THREAT OF SHOWERS SHOULD KEEP HIGHS ON THE COOLER SIDE WEDNESDAY AND THURSDAY...5 TO 7 DEGREES BELOW NORMALS. && .AVIATION...TODAY AND TONIGHT 1130 AM CDT FRI MAY 17 2013 SFC FRONT LAYING WEST-EAST ACROSS SOUTHERN MN/WESTERN WI CONTINUES TO BE A FOCUS FOR SHRA/ISOLD TS DEVELOPMENT LATE THIS MORNING. NOT MUCH-IF ANY INSTABILITY OR LOW LEVEL MOISTURE TRANSPORT INTO THE FRONT THOUGH...PER MESO MODELS. INDICATIONS THAT THE PCPN IS GETTING SOME ENHANCEMENT ON ITS WESTERN EDGES FROM AN UPPER LEVEL SHORTWAVE TROUGH...PER LATEST WATER VAPOR SATELLITE IMAGERY. THIS FEATURE IS MOVING EAST...AND NAM12/HRRR SUGGEST THAT THE PCPN WILL MOVE WITH IT. WILL TREND THE TAFS THIS WAY. THE HRRR DOES HINT THAT THE FRONT WON/T MOVE TOO FAR NORTH THIS EVENING...AND COULD SERVE AS A FOCUS FOR MORE SCT SHRA/TS. ARXLAPS ALSO HAS THIS POTENTIAL...WEST OF THE MISSISSIPPI RIVER. CONFIDENCE SHAKY ON THIS POSSIBILITY...AND WILL LIKELY LEAVE OUT OF THE KRST TAF FOR NOW. WITH THE PROLONGED PERIOD OF RAIN MOISTENING THE BOUNDARY LAYER FOR KRST/KLSE...FOG/STRATUS BECOMES A CONCERN OVERNIGHT. KLSE LIKELY DECOUPLES RESULTING IN LIGHT/VRB WINDS. KRST PROBABLY STICKS AROUND 6-8KTS FROM THE ESE. NUMERICAL GUIDANCE AND BUFKIT SOUNDINGS POINT TO GOOD SATURATION UNDER THE NOCTURNAL INVERSION THAT VSBY RESTRICTIONS ARE LIKELY...ALONG WITH LOW STRATUS. MVFR/IFR CONDITIONS ARE FAVORED INTO SATURDAY MORNING. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. && $$ SHORT TERM...ZT LONG TERM....ZT AVIATION.....RIECK