Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/16/12


AREA FORECAST DISCUSSION
NWS MIAMI FL
158 PM EDT FRI SEP 14 2012 .AVIATION... SO FAR CONVECTION HAS NOT BECOME ESTABLISHED ACROSS THE SOUTH FLORIDA PENINSULA. WITH MODERATE EASTERLY FLOW ACROSS THE REGION CONVECTION IS EXPECTED TO BE MORE INLAND AND IN THE WESTERN PART OF THE PENINSULA, WITH EAST COAST TAF SITES ASSIGNED VCSH AT 18Z AND VCTS ASSIGNED TERMINAL KAPF AT 19Z WITH CONVECTION MAYBE STARTING LATER AROUND 19-20Z. WITH A PASSING SHOWER AT EAST COAST TERMINALS BRIEF SUB-VFR CONDITIONS POSSIBLE. IF THUNDERSTORMS DO DEVELOP IN VICINITY OF TERMINAL KAPF BRIEF PERIODS OF IFR CONDITIONS MAY BE POSSIBLE. 60 && .PREV DISCUSSION... /ISSUED 1017 AM EDT FRI SEP 14 2012/ UPDATE... WEAKER EASTERLY FLOW IS OCCURRING ACROSS THE REGION THIS MORNING...AS THE SURFACE BOUNDARY HAS DRIFTED A LITTLE SOUTH IN THE FLORIDA STRAITS AND SURFACE HIGH PRESSURE HAS WEAKENED DUE TO A SHORTWAVE TROUGH MOVING ACROSS THE GREAT LAKES. ISOLATED TO WIDELY SCATTERED SHOWERS HAVE DEVELOPED OVER THE ATLANTIC...MAINLY EAST OF PALM BEACH COUNTY. THE 12Z SOUNDING SHOWED A THIN DRY LAYER BETWEEN 700 AND 750MB...WITH STEEPER LAPSE RATES ABOVE THIS INVERSION. SO THE MODIFIED SOUNDING SHOWS THERE IS A LITTLE MORE POTENTIAL FOR WIND TODAY...BUT STILL ONLY THE TYPICAL 40-50 MPH IN THE STRONGEST STORMS...AND THIS WILL MAINLY BE FOR THE INTERIOR AND THE GULF COAST. WITH THE LIGHTER FLOW...ISOLATED TO LOW END SCATTERED SHOWERS AND A FEW THUNDERSTORMS WILL BE POSSIBLE FOR THE EAST COAST AREAS THROUGH MID AFTERNOON. AFTER THAT TIME...A GULF COAST SEA BREEZE SHOULD DEVELOP...WITH THE BULK OF THE ACTIVITY FOCUSING IN THIS REGION. NO MAJOR UPDATES WERE NEEDED TO THE GOING FORECAST. PREV DISCUSSION... /ISSUED 744 AM EDT FRI SEP 14 2012/ AVIATION... THE RIDGE OF HIGH PRESSURE EXTENDING SOUTHWEST INTO THE SE U.S. BEGINS TO WEAKEN AND MOVE NORTHEAST AS A LOW PRESSURE SYSTEM AND THE ASSOCIATED COLD FRONT MOVE TOWARD THE EAST U.S. COAST TODAY INTO SATURDAY. WITH THE PRESSURE GRADIENT OVER SOUTH FLORIDA WEAKENING...THE EASTERLY WIND FLOW WILL PERSIST TODAY INTO SATURDAY BUT MUCH LOWER. CURRENTLY WIDELY SCATTERED SHRA MOVING WEST FROM THE ATLC ONSHORE WITH VERY BRIEF MVFR CIG/VSBY AT ANY E COAST TERMINAL BUT ONLY VCSH IN TAFS AT THIS TIME. AFT 15Z...ISOLD TSRA POSSIBLE BUT SHOULD BE WEST OF TERMINALS SO NO VCTS IN TAFS. WINDS VARIABLE TO ENE < 10 KNOTS BECOMING AFT 14Z 10-13 KNOTS WITH GUSTS TO THE MID/UPPER TEENS. AT KAPF...VFR THROUGH PERIOD WITH VCSH AFT 18Z. TSRA POSSIBLE BUT NOT IN TAF AT THIS TIME. SURFACE WIND CURRENTLY NE < 10 KNOTS BECOMING 10 TO 12 KNOTS AFT 15Z. PREV DISCUSSION... /ISSUED 200 AM EDT FRI SEP 14 2012/ SHORT TERM (TODAY-SUNDAY)... THE LATEST NUMERICAL GUIDANCE REMAINS IN GOOD AGREEMENT OVER THE WEEKEND AND GENERALLY INDICATES LIGHT TO MODERATE EASTERLY FLOW CONTINUING JUST NORTH OF A WEAK TROUGH OR WHAT IS LEFT OF THE FRONTAL BOUNDARY THAT MOVED THROUGH A FEW DAYS AGO AND HIGH PRESSURE TO THE NORTH. ALTHOUGH THE RAINFALL COVERAGE TODAY IS EXPECTED TO BE LESS THAN YESTERDAY...SCATTERED SHOWERS OVER THE ADJACENT ATLANTIC WATERS SPREADING ASHORE ACROSS PORTIONS OF THE EAST COAST AREAS EARLY THIS MORNING WILL REMAIN POSSIBLE ONCE AGAIN. THIS LINES UP WELL WITH THE LATEST HRRR AND WRF MODEL REFLECTIVITIES TODAY. FOR THE AFTERNOON...EXPECT THIS ACTIVITY TO SPREAD INLAND AND BECOME CONCENTRATED OVER THE INTERIOR AND WESTERN AREAS THROUGH THE EVENING HOURS BEFORE DIMINISHING. THE EASTERLY FLOW HAS WEAKENED COMPARED TO YESTERDAY...WHICH SHOULD ALLOW A WEST COAST SEA BREEZE TO BECOME ESTABLISHED THIS AFTERNOON. THE MAIN IMPACTS FROM THIS AFTERNOON/EVENING ACTIVITY WILL BE THE POTENTIAL FOR PERIODS WITH HEAVY RAIN AND GUSTY WINDS WITH ANY STRONGER STORMS THAT DEVELOP. HOWEVER...MODEL SOUNDINGS ARE NOT THAT IMPRESSIVE AND INDICATE MEAGER MID-LEVEL LAPSE RATES WITH NEAR AVERAGE 500 MB TEMPERATURES. OVER THE WEEKEND...SIMILAR CONDITIONS WILL BE EXPECTED EACH DAY WITH TEMPERATURES REMAINING NEAR OR AROUND NORMAL. LONG TERM (SUNDAY NIGHT-THURSDAY)... MODELS CONTINUE TO INDICATE UPPER HEIGHTS FALLING AHEAD OF A SHORTWAVE TROUGH PROGGED TO TRANSLATE EAST THEN NORTHEAST ACROSS THE REGION WELL NORTHWEST OF OUR LOCAL AREA SUNDAY THROUGH TUESDAY. THIS SHORTWAVE COMBINED WITH ANOTHER POTENT PIECE OF ENERGY DIVING SOUTHEAST OVER THE PLAIN STATES WILL QUICKLY AMPLIFY THE OVERALL UPPER PATTERN ACROSS THE COUNTRY CHARACTERIZED WITH A DEEPENING TROUGH OVER THE EASTERN STATES AND RIDGING OUT WEST. THE ATTENDANT COLD FRONT ASSOCIATED WITH THE LEAD SHORTWAVE IS FORECAST TO SWEEP EAST ACROSS THE REGION AND GENERALLY LAYOUT FROM EAST TO WEST AND STALL JUST NORTH OF OUR LOCAL AREA SOMETIME AROUND THE MID-WEEK TIME FRAME AS IT LOSES ITS UPPER SUPPORT. THE ECMWF AND GFS/GFS ENSEMBLE MEAN SOLUTIONS APPEAR TO BE IN BETTER AGREEMENT WITH THIS BOUNDARY SPATIALLY AND TEMPORALLY THROUGH THIS...WHEREAS...24 HRS AGO INDICATED LARGER DIFFERENCES. IF THIS VERIFIES...EXPECT THE LOW-LEVEL FLOW LOCALLY TO GRADUALLY VEER TO THE SOUTH AND SOUTHWEST MONDAY THROUGH TUESDAY AS A WARM FRONT LIFTS NORTH OVER THE EASTERN GULF AND FL. THE RESULTANT DEEP AND MOIST SOUTHWEST FLOW SHOULD TRANSLATE TO HIGHER THAN NORMAL RAIN CHANCES...ESPECIALLY OVER THE NORTH AND NORTHEASTERN SECTIONS OF THE FORECAST AREA FROM THE LAKE TO PALM BEACH REGION. DUE TO THE BETTER AGREEMENT BETWEEN THE LATEST MODEL GUIDANCE AND PERSISTENCE FROM RUN TO RUN...WILL SLIGHTLY INCREASE THE RAINFALL PROBABILITIES MONDAY THROUGH THE MID-WEEK PERIOD. MARINE... LIGHT TO MODERATE EASTERLY WINDS AND WILL PERSIST THROUGH THE WEEKEND WITH SCATTERED SHOWERS AND STORMS POSSIBLE...ESPECIALLY OVERNIGHT AND THROUGH THE EARLY MORNING HOURS ACROSS THE ATLANTIC WATERS. SEAS WILL GRADUALLY TREND DOWN THROUGH THE WEEKEND TO AROUND NORMAL. WINDS ARE FORECAST TO SHIFT SOUTH AND POSSIBLY SOUTHWEST SOMETIME NEXT WEEK FROM MONDAY THROUGH WEDNESDAY AS ANOTHER FRONTAL BOUNDARY APPROACHES AND STALLS NORTH OF THE MARINE AREA. FIRE WEATHER... MOIST CONDITIONS WILL KEEP RH`S WELL ABOVE CRITICAL LEVELS THROUGH THE FORECAST PERIOD. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 77 86 76 88 / 20 30 20 40 FORT LAUDERDALE 78 88 78 88 / 20 30 20 40 MIAMI 78 88 78 87 / 20 40 20 40 NAPLES 74 91 75 90 / 30 40 30 40 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...84/AK AVIATION/RADAR...60/BD
AREA FORECAST DISCUSSION
NWS MIAMI FL
1017 AM EDT FRI SEP 14 2012 .UPDATE... WEAKER EASTERLY FLOW IS OCCURRING ACROSS THE REGION THIS MORNING...AS THE SURFACE BOUNDARY HAS DRIFTED A LITTLE SOUTH IN THE FLORIDA STRAITS AND SURFACE HIGH PRESSURE HAS WEAKENED DUE TO A SHORTWAVE TROUGH MOVING ACROSS THE GREAT LAKES. ISOLATED TO WIDELY SCATTERED SHOWERS HAVE DEVELOPED OVER THE ATLANTIC...MAINLY EAST OF PALM BEACH COUNTY. THE 12Z SOUNDING SHOWED A THIN DRY LAYER BETWEEN 700 AND 750MB...WITH STEEPER LAPSE RATES ABOVE THIS INVERSION. SO THE MODIFIED SOUNDING SHOWS THERE IS A LITTLE MORE POTENTIAL FOR WIND TODAY...BUT STILL ONLY THE TYPICAL 40-50 MPH IN THE STRONGEST STORMS...AND THIS WILL MAINLY BE FOR THE INTERIOR AND THE GULF COAST. WITH THE LIGHTER FLOW...ISOLATED TO LOW END SCATTERED SHOWERS AND A FEW THUNDERSTORMS WILL BE POSSIBLE FOR THE EAST COAST AREAS THROUGH MID AFTERNOON. AFTER THAT TIME...A GULF COAST SEA BREEZE SHOULD DEVELOP...WITH THE BULK OF THE ACTIVITY FOCUSING IN THIS REGION. NO MAJOR UPDATES WERE NEEDED TO THE GOING FORECAST. && .PREV DISCUSSION... /ISSUED 744 AM EDT FRI SEP 14 2012/ AVIATION... THE RIDGE OF HIGH PRESSURE EXTENDING SOUTHWEST INTO THE SE U.S. BEGINS TO WEAKEN AND MOVE NORTHEAST AS A LOW PRESSURE SYSTEM AND THE ASSOCIATED COLD FRONT MOVE TOWARD THE EAST U.S. COAST TODAY INTO SATURDAY. WITH THE PRESSURE GRADIENT OVER SOUTH FLORIDA WEAKENING...THE EASTERLY WIND FLOW WILL PERSIST TODAY INTO SATURDAY BUT MUCH LOWER. CURRENTLY WIDELY SCATTERED SHRA MOVING WEST FROM THE ATLC ONSHORE WITH VERY BRIEF MVFR CIG/VSBY AT ANY E COAST TERMINAL BUT ONLY VCSH IN TAFS AT THIS TIME. AFT 15Z...ISOLD TSRA POSSIBLE BUT SHOULD BE WEST OF TERMINALS SO NO VCTS IN TAFS. WINDS VARIABLE TO ENE < 10 KNOTS BECOMING AFT 14Z 10-13 KNOTS WITH GUSTS TO THE MID/UPPER TEENS. AT KAPF...VFR THROUGH PERIOD WITH VCSH AFT 18Z. TSRA POSSIBLE BUT NOT IN TAF AT THIS TIME. SURFACE WIND CURRENTLY NE < 10 KNOTS BECOMING 10 TO 12 KNOTS AFT 15Z. PREV DISCUSSION... /ISSUED 200 AM EDT FRI SEP 14 2012/ SHORT TERM (TODAY-SUNDAY)... THE LATEST NUMERICAL GUIDANCE REMAINS IN GOOD AGREEMENT OVER THE WEEKEND AND GENERALLY INDICATES LIGHT TO MODERATE EASTERLY FLOW CONTINUING JUST NORTH OF A WEAK TROUGH OR WHAT IS LEFT OF THE FRONTAL BOUNDARY THAT MOVED THROUGH A FEW DAYS AGO AND HIGH PRESSURE TO THE NORTH. ALTHOUGH THE RAINFALL COVERAGE TODAY IS EXPECTED TO BE LESS THAN YESTERDAY...SCATTERED SHOWERS OVER THE ADJACENT ATLANTIC WATERS SPREADING ASHORE ACROSS PORTIONS OF THE EAST COAST AREAS EARLY THIS MORNING WILL REMAIN POSSIBLE ONCE AGAIN. THIS LINES UP WELL WITH THE LATEST HRRR AND WRF MODEL REFLECTIVITIES TODAY. FOR THE AFTERNOON...EXPECT THIS ACTIVITY TO SPREAD INLAND AND BECOME CONCENTRATED OVER THE INTERIOR AND WESTERN AREAS THROUGH THE EVENING HOURS BEFORE DIMINISHING. THE EASTERLY FLOW HAS WEAKENED COMPARED TO YESTERDAY...WHICH SHOULD ALLOW A WEST COAST SEA BREEZE TO BECOME ESTABLISHED THIS AFTERNOON. THE MAIN IMPACTS FROM THIS AFTERNOON/EVENING ACTIVITY WILL BE THE POTENTIAL FOR PERIODS WITH HEAVY RAIN AND GUSTY WINDS WITH ANY STRONGER STORMS THAT DEVELOP. HOWEVER...MODEL SOUNDINGS ARE NOT THAT IMPRESSIVE AND INDICATE MEAGER MID-LEVEL LAPSE RATES WITH NEAR AVERAGE 500 MB TEMPERATURES. OVER THE WEEKEND...SIMILAR CONDITIONS WILL BE EXPECTED EACH DAY WITH TEMPERATURES REMAINING NEAR OR AROUND NORMAL. LONG TERM (SUNDAY NIGHT-THURSDAY)... MODELS CONTINUE TO INDICATE UPPER HEIGHTS FALLING AHEAD OF A SHORTWAVE TROUGH PROGGED TO TRANSLATE EAST THEN NORTHEAST ACROSS THE REGION WELL NORTHWEST OF OUR LOCAL AREA SUNDAY THROUGH TUESDAY. THIS SHORTWAVE COMBINED WITH ANOTHER POTENT PIECE OF ENERGY DIVING SOUTHEAST OVER THE PLAIN STATES WILL QUICKLY AMPLIFY THE OVERALL UPPER PATTERN ACROSS THE COUNTRY CHARACTERIZED WITH A DEEPENING TROUGH OVER THE EASTERN STATES AND RIDGING OUT WEST. THE ATTENDANT COLD FRONT ASSOCIATED WITH THE LEAD SHORTWAVE IS FORECAST TO SWEEP EAST ACROSS THE REGION AND GENERALLY LAYOUT FROM EAST TO WEST AND STALL JUST NORTH OF OUR LOCAL AREA SOMETIME AROUND THE MID-WEEK TIME FRAME AS IT LOSES ITS UPPER SUPPORT. THE ECMWF AND GFS/GFS ENSEMBLE MEAN SOLUTIONS APPEAR TO BE IN BETTER AGREEMENT WITH THIS BOUNDARY SPATIALLY AND TEMPORALLY THROUGH THIS...WHEREAS...24 HRS AGO INDICATED LARGER DIFFERENCES. IF THIS VERIFIES...EXPECT THE LOW-LEVEL FLOW LOCALLY TO GRADUALLY VEER TO THE SOUTH AND SOUTHWEST MONDAY THROUGH TUESDAY AS A WARM FRONT LIFTS NORTH OVER THE EASTERN GULF AND FL. THE RESULTANT DEEP AND MOIST SOUTHWEST FLOW SHOULD TRANSLATE TO HIGHER THAN NORMAL RAIN CHANCES...ESPECIALLY OVER THE NORTH AND NORTHEASTERN SECTIONS OF THE FORECAST AREA FROM THE LAKE TO PALM BEACH REGION. DUE TO THE BETTER AGREEMENT BETWEEN THE LATEST MODEL GUIDANCE AND PERSISTENCE FROM RUN TO RUN...WILL SLIGHTLY INCREASE THE RAINFALL PROBABILITIES MONDAY THROUGH THE MID-WEEK PERIOD. MARINE... LIGHT TO MODERATE EASTERLY WINDS AND WILL PERSIST THROUGH THE WEEKEND WITH SCATTERED SHOWERS AND STORMS POSSIBLE...ESPECIALLY OVERNIGHT AND THROUGH THE EARLY MORNING HOURS ACROSS THE ATLANTIC WATERS. SEAS WILL GRADUALLY TREND DOWN THROUGH THE WEEKEND TO AROUND NORMAL. WINDS ARE FORECAST TO SHIFT SOUTH AND POSSIBLY SOUTHWEST SOMETIME NEXT WEEK FROM MONDAY THROUGH WEDNESDAY AS ANOTHER FRONTAL BOUNDARY APPROACHES AND STALLS NORTH OF THE MARINE AREA. FIRE WEATHER... MOIST CONDITIONS WILL KEEP RH`S WELL ABOVE CRITICAL LEVELS THROUGH THE FORECAST PERIOD. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 86 77 86 76 / 30 20 30 20 FORT LAUDERDALE 86 78 88 78 / 30 20 30 20 MIAMI 87 78 88 78 / 30 20 40 20 NAPLES 89 74 91 75 / 40 30 40 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...84/AK AVIATION/RADAR...60/BD
AREA FORECAST DISCUSSION
NWS MIAMI FL
744 AM EDT FRI SEP 14 2012 .AVIATION... THE RIDGE OF HIGH PRESSURE EXTENDING SOUTHWEST INTO THE SE U.S. BEGINS TO WEAKEN AND MOVE NORTHEAST AS A LOW PRESSURE SYSTEM AND THE ASSOCIATED COLD FRONT MOVE TOWARD THE EAST U.S. COAST TODAY INTO SATURDAY. WITH THE PRESSURE GRADIENT OVER SOUTH FLORIDA WEAKENING...THE EASTERLY WIND FLOW WILL PERSIST TODAY INTO SATURDAY BUT MUCH LOWER. CURRENTLY WIDELY SCATTERED SHRA MOVING WEST FROM THE ATLC ONSHORE WITH VERY BRIEF MVFR CIG/VSBY AT ANY E COAST TERMINAL BUT ONLY VCSH IN TAFS AT THIS TIME. AFT 15Z...ISOLD TSRA POSSIBLE BUT SHOULD BE WEST OF TERMINALS SO NO VCTS IN TAFS. WINDS VARIABLE TO ENE < 10 KNOTS BECOMING AFT 14Z 10-13 KNOTS WITH GUSTS TO THE MID/UPPER TEENS. AT KAPF...VFR THROUGH PERIOD WITH VCSH AFT 18Z. TSRA POSSIBLE BUT NOT IN TAF AT THIS TIME. SURFACE WIND CURRENTLY NE < 10 KNOTS BECOMING 10 TO 12 KNOTS AFT 15Z. && .PREV DISCUSSION... /ISSUED 200 AM EDT FRI SEP 14 2012/ SHORT TERM (TODAY-SUNDAY)... THE LATEST NUMERICAL GUIDANCE REMAINS IN GOOD AGREEMENT OVER THE WEEKEND AND GENERALLY INDICATES LIGHT TO MODERATE EASTERLY FLOW CONTINUING JUST NORTH OF A WEAK TROUGH OR WHAT IS LEFT OF THE FRONTAL BOUNDARY THAT MOVED THROUGH A FEW DAYS AGO AND HIGH PRESSURE TO THE NORTH. ALTHOUGH THE RAINFALL COVERAGE TODAY IS EXPECTED TO BE LESS THAN YESTERDAY...SCATTERED SHOWERS OVER THE ADJACENT ATLANTIC WATERS SPREADING ASHORE ACROSS PORTIONS OF THE EAST COAST AREAS EARLY THIS MORNING WILL REMAIN POSSIBLE ONCE AGAIN. THIS LINES UP WELL WITH THE LATEST HRRR AND WRF MODEL REFLECTIVITIES TODAY. FOR THE AFTERNOON...EXPECT THIS ACTIVITY TO SPREAD INLAND AND BECOME CONCENTRATED OVER THE INTERIOR AND WESTERN AREAS THROUGH THE EVENING HOURS BEFORE DIMINISHING. THE EASTERLY FLOW HAS WEAKENED COMPARED TO YESTERDAY...WHICH SHOULD ALLOW A WEST COAST SEA BREEZE TO BECOME ESTABLISHED THIS AFTERNOON. THE MAIN IMPACTS FROM THIS AFTERNOON/EVENING ACTIVITY WILL BE THE POTENTIAL FOR PERIODS WITH HEAVY RAIN AND GUSTY WINDS WITH ANY STRONGER STORMS THAT DEVELOP. HOWEVER...MODEL SOUNDINGS ARE NOT THAT IMPRESSIVE AND INDICATE MEAGER MID-LEVEL LAPSE RATES WITH NEAR AVERAGE 500 MB TEMPERATURES. OVER THE WEEKEND...SIMILAR CONDITIONS WILL BE EXPECTED EACH DAY WITH TEMPERATURES REMAINING NEAR OR AROUND NORMAL. LONG TERM (SUNDAY NIGHT-THURSDAY)... MODELS CONTINUE TO INDICATE UPPER HEIGHTS FALLING AHEAD OF A SHORTWAVE TROUGH PROGGED TO TRANSLATE EAST THEN NORTHEAST ACROSS THE REGION WELL NORTHWEST OF OUR LOCAL AREA SUNDAY THROUGH TUESDAY. THIS SHORTWAVE COMBINED WITH ANOTHER POTENT PIECE OF ENERGY DIVING SOUTHEAST OVER THE PLAIN STATES WILL QUICKLY AMPLIFY THE OVERALL UPPER PATTERN ACROSS THE COUNTRY CHARACTERIZED WITH A DEEPENING TROUGH OVER THE EASTERN STATES AND RIDGING OUT WEST. THE ATTENDANT COLD FRONT ASSOCIATED WITH THE LEAD SHORTWAVE IS FORECAST TO SWEEP EAST ACROSS THE REGION AND GENERALLY LAYOUT FROM EAST TO WEST AND STALL JUST NORTH OF OUR LOCAL AREA SOMETIME AROUND THE MID-WEEK TIME FRAME AS IT LOSES ITS UPPER SUPPORT. THE ECMWF AND GFS/GFS ENSEMBLE MEAN SOLUTIONS APPEAR TO BE IN BETTER AGREEMENT WITH THIS BOUNDARY SPATIALLY AND TEMPORALLY THROUGH THIS...WHEREAS...24 HRS AGO INDICATED LARGER DIFFERENCES. IF THIS VERIFIES...EXPECT THE LOW-LEVEL FLOW LOCALLY TO GRADUALLY VEER TO THE SOUTH AND SOUTHWEST MONDAY THROUGH TUESDAY AS A WARM FRONT LIFTS NORTH OVER THE EASTERN GULF AND FL. THE RESULTANT DEEP AND MOIST SOUTHWEST FLOW SHOULD TRANSLATE TO HIGHER THAN NORMAL RAIN CHANCES...ESPECIALLY OVER THE NORTH AND NORTHEASTERN SECTIONS OF THE FORECAST AREA FROM THE LAKE TO PALM BEACH REGION. DUE TO THE BETTER AGREEMENT BETWEEN THE LATEST MODEL GUIDANCE AND PERSISTENCE FROM RUN TO RUN...WILL SLIGHTLY INCREASE THE RAINFALL PROBABILITIES MONDAY THROUGH THE MID-WEEK PERIOD. MARINE... LIGHT TO MODERATE EASTERLY WINDS AND WILL PERSIST THROUGH THE WEEKEND WITH SCATTERED SHOWERS AND STORMS POSSIBLE...ESPECIALLY OVERNIGHT AND THROUGH THE EARLY MORNING HOURS ACROSS THE ATLANTIC WATERS. SEAS WILL GRADUALLY TREND DOWN THROUGH THE WEEKEND TO AROUND NORMAL. WINDS ARE FORECAST TO SHIFT SOUTH AND POSSIBLY SOUTHWEST SOMETIME NEXT WEEK FROM MONDAY THROUGH WEDNESDAY AS ANOTHER FRONTAL BOUNDARY APPROACHES AND STALLS NORTH OF THE MARINE AREA. FIRE WEATHER... MOIST CONDITIONS WILL KEEP RH`S WELL ABOVE CRITICAL LEVELS THROUGH THE FORECAST PERIOD. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 86 77 86 76 / 30 20 30 20 FORT LAUDERDALE 86 78 88 78 / 20 20 30 20 MIAMI 87 78 88 78 / 30 20 40 20 NAPLES 89 74 91 75 / 30 30 40 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...84/AK AVIATION/RADAR...60/BD
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
415 AM EDT FRI SEP 14 2012 .DISCUSSION... ...BOATING CONDITIONS LESS THAN IDEAL BUT NO ADVISORIES IN EFFECT... ...PRECIPITATION CHANCES INCREASING FOR EARLY NEXT WEEK... TODAY/TONIGHT...ONSHORE FLOW WILL CONTINUE TODAY BUT SFC HIGH PRESSURE RIDGE WILL BEGIN TO WEAKEN AS FRONTAL BOUNDARY APPROACHES THE EASTERN SEABOARD. LIKEWISE IN THE MID LEVELS...HIGH PRESSURE RIDGE IS WEAKENING WHICH MAY PRODUCE A BETTER CHANCE FOR THUNDER. IN ADDITION...THE RESULTING WEAKER STEERING FLOW WILL PRODUCE SLOWER MOVING SHOWERS/ISOLATED STORMS AND CONTRIBUTE TO LOCALLY HEAVIER RAINFALL. MAX TEMPS UPPER 80S COAST/LOWER 90S INTERIOR. HAVE BEEN TRACKING A SMALL LOW LEVEL PERTURBATION IN THE ONSHORE FLOW SHOWN BY THE RUC MODEL WHICH IS GENERATING CLUSTERS OF SHOWERS OFFSHORE. EXPECT THESE SHOWERS TO REACH THE COAST (BREVARD SOUTHWARD) LATER THIS MORNING. SHOWERS SHOULD PUSH WELL INLAND WITH SOME DEVELOPMENT OF ADDITIONAL SHOWERS INLAND FROM THE COAST AS DAYTIME INSTABILITY INCREASES. AND AS MENTIONED ABOVE...A FEW OF THESE SHOWERS HAVE A SLIGHTLY BETTER CHANCE OF DEVELOPING INTO LIGHTNING STORMS THAN PREVIOUS DAYS. SO HAVE DRAWN 30-40 POPS. SUFFICIENT LOW LEVEL MOISTURE AND ONSHORE FLOW SHOULD REMAIN IN PLACE TONIGHT TO SUPPORT CHANCE FOR SHOWERS ALONG THE COAST SOUTH OF THE CAPE...SLIGHT CHANCE ELSEWHERE. SAT-SUN...SURFACE HIGH PRESSURE WILL AGAIN ESTABLISH ITSELF ACROSS THE EASTERN SEABOARD. THIS WILL ACT TO REINFORCE NORTHEAST OR EAST-NORTHEAST LOW-LEVEL FLOW ACROSS EAST CENTRAL FLORIDA. HOWEVER...A DRIER AND MORE STABLE AIR MASS WILL SCOUR OUT DEEP LAYER MOISTURE ACROSS THE EASTERN PENINSULA. FOR NOW WILL KEEP INHERITED 30 PERCENT POPS OVER THE AREA WITH SCATTERED SHOWERS AND ISOLATED AFTERNOON STORMS. THE FOCUS OF PRECIPITATION WILL SHIFT INTO THE INTERIOR DURING THE AFTERNOON WITH THE EAST COAST SEA BREEZE. WILL GO WITH A SLIGHT CHANCE...20 PERCENT POP ALONG THE COAST FOR SUN WITH 30 PERCENT CHANCES INLAND...AGAIN WITH GREATEST CHANCES ACROSS THE INTERIOR INTO THE AFTERNOON. MAINLY A NORTHERLY COMPONENT FOR STEERING FLOW AROUND 5 MPH EACH DAY. MON-THU...SURFACE HIGH PRESSURE JUST OFF OF THE MID ATLANTIC COAST EARLY IN THE PERIOD WILL GRADUALLY SHIFT EASTWARD INTO THE WESTERN ATLANTIC AHEAD OF AN APPROACHING FRONTAL BOUNDARY. HIGH PRESSURE WILL AGAIN BUILD INTO THE EASTERN SEABOARD ON THU. THE AFOREMENTIONED FRONT WILL MOVE INTO NORTH FLORIDA MON OVERNIGHT AND WILL APPEAR TO GET HUNG UP...QUASI-STATIONARY...OVER NORTH-CENTRAL FLORIDA THROUGH THE REMAINDER OF THE EXTENDED. MOISTURE VALUES WILL SURGE TOWARD THIS FEATURE LATE ON MON POOLING ACROSS EAST CENTRAL FLORIDA EACH DAY. PRECIPITATION CHANCES WILL BE ON THE RISE WITH OCCASIONAL MID-LEVEL IMPULSES MOVING THROUGH THE REGION IN THE SOUTHWEST FLOW ALOFT. EXPECT 40 TO 50 PERCENT PRECIPITATION CHANCES EACH DAY. THE PREVIOUS ONSHORE FLOW REGIME WILL RESPOND MON TO THE APPROACHING FRONTAL BOUNDARY ACROSS THE DEEP SOUTH. WINDS WILL VEER TO SOUTHEAST ON MON...SOUTHERLY MON NIGHT AND SOUTHWEST ON TUE AS THE BOUNDARY ENTERS INTO NORTH-CENTRAL FLORIDA. AN UPPER TROUGH TRAVERSING THE DEEP SOUTH WILL WEAKEN BUT WILL STILL MOVE INTO THE AREA ON TUE. THIS UPPER TROUGHING WILL ACT TO PUSH DEEP LAYER RIDGING FURTHER INTO THE WESTERN ATLANTIC. AN UPPER JET SITUATED ALONG THE EASTERN SEABOARD EXTENDING INTO THE NORTH GOMEX WILL PROVIDE UPPER DIFFLUENCE ACROSS THE REGION DURING THIS TIME. STEERING FLOW FOR STORMS MON-THU WILL BE OUT OF THE SOUTHWEST WHICH FAVORS CONVECTION PILING UP ACROSS THE EASTERN PENINSULA LATE EACH DAY AND EVENING. AFTERNOON HIGHS WILL CONTINUE NEAR SEASONAL NORMS WITH OVERNIGHT LOWS SLIGHTLY ABOVE CLIMO. && .AVIATION... NOT MUCH CHANGE IN THE PATTERN WITH ONSHORE MOVING SHOWERS AND WILL CONTINUE TO HANDLE WITH VCSH AT TERMINALS. THERE IS A SLIGHT CHANCE FOR THUNDER. LOW LEVEL WINDS WILL BE 10-15 KNOTS BUT EXPECT SOME GUSTS TO 20 KNOTS ESP IN AND NEAR SHOWERS. && .MARINE... TODAY...HIGH PRESSURE RIDGE NORTH OF THE AREA WILL MAINTAIN AN ONSHORE FLOW BUT WEAKEN SLIGHTLY. WIND SPEEDS 10-15 KNOTS BUT PRESSURE GRADIENT LOOKS A LITTLE TIGHTER ACROSS VOLUSIA AND BREVARD COUNTY WATERS WHICH SHOULD PRODUCE A SOLID 15 KNOTS AT LEAST THIS MORNING. HIGHER GUSTS UP TO 25 KNOTS POSSIBLE IN SHOWERS. THERE IS A SLIGHTLY BETTER CHANCE FOR A FEW SHOWERS TO DEVELOP INTO LIGHTNING STORMS. CHOPPY SEAS 4 TO 5 FEET WITH UP TO 6 FEET POSSIBLE OFFSHORE VOLUSIA AND BREVARD. OFTEN CONDITIONS ON THE OPEN ATLC ARE WORSE THAN WE EXPECT...SO WILL HEADLINE SMALL CRAFT CAUTION THERE BUT SMALL CRAFT ADVISORIES DO NOT LOOK WARRANTED. SAT...SURFACE HIGH PRESSURE WILL SETTLE INTO THE EASTERN SEABOARD ON THIS DAY. NORTHEAST WINDS OF 10-15 KTS WILL BE COMMON ACROSS THE COASTAL WATERS. A FEW SHOWERS AND PERHAPS A STORM WILL BE POSSIBLE WITH DIRECTION OUT OF EITHER THE NORTH OR NORTHEAST. THE LATEST WAVE WATCH MODEL CONTINUES TO INDICATE SOME LONG PERIOD SWELLS BOOSTING SEA HEIGHTS TO 5-6 FT SAT OVERNIGHT. THESE SWELLS ARE FROM TROPICAL CYCLONE NADINE...AND IF THEY MATERIALIZE...WOULD PRODUCE DANGEROUS INLET CONDITIONS DURING EBB TIDES. SUN-TUE...A HIGH PRESSURE SYSTEM OVER THE EASTERN SEABOARD WILL GRADUALLY GET NUDGED EASTWARD INTO THE WESTERN ATLANTIC THROUGH THIS TIME. ONSHORE FLOW CONTINUES THROUGH SUN...BUT WILL BEGIN TO VEER TO SOUTHEAST LATE SUN OVERNIGHT INTO MON...AND SOUTHERLY MON OVERNIGHT...BECOMING SOUTHWEST ON TUE. THIS WILL BE THE RESULT OF AN APPROACHING FRONTAL BOUNDARY TO THE NORTH. WIND SPEEDS MAINLY 10-15 KTS. ONLY A SMALL THREAT FOR SHOWERS OR LIGHTNING STORMS WILL BE FORECAST ON SUN. MOISTURE WILL BEGIN TO POOL ACROSS THE AREA LATE ON MON AHEAD OF THE BOUNDARY WITH OFFSHORE MOVING STORMS POSSIBLE LATE IN THE DAY/EVENING ON MON. GREATER CHANCES FOR STORMS MOVING OFFSHORE WILL OCCUR ON TUE AS THE WEAK FRONTAL BOUNDARY SETTLES INTO NORTH FLORIDA. LONG PERIOD SWELLS WITH SEA HEIGHTS TO 5-6 FT ARE FORECAST TO CONTINUE SUN-SUN EVENING. PERSISTENT LONG PERIOD SWELLS CONTINUE INTO MON-TUE BUT SEA HEIGHTS WILL SUBSIDE TO 3 TO 5 FT DURING THIS TIME. && .PRELIMINARY POINT TEMPS/POPS... DAB 87 75 88 74 / 30 20 20 20 MCO 90 73 91 72 / 40 20 30 20 MLB 88 77 88 76 / 40 30 30 20 VRB 88 75 88 74 / 40 30 30 20 LEE 90 73 91 73 / 30 20 30 20 SFB 89 73 91 73 / 30 20 30 20 ORL 90 74 91 74 / 30 20 30 20 FPR 87 75 88 74 / 40 30 30 20 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ SHORT TERM...KELLY LONG TERM....SEDLOCK
AREA FORECAST DISCUSSION
NWS MIAMI FL
200 AM EDT FRI SEP 14 2012 .SHORT TERM (TODAY-SUNDAY)... THE LATEST NUMERICAL GUIDANCE REMAINS IN GOOD AGREEMENT OVER THE WEEKEND AND GENERALLY INDICATES LIGHT TO MODERATE EASTERLY FLOW CONTINUING JUST NORTH OF A WEAK TROUGH OR WHAT IS LEFT OF THE FRONTAL BOUNDARY THAT MOVED THROUGH A FEW DAYS AGO AND HIGH PRESSURE TO THE NORTH. ALTHOUGH THE RAINFALL COVERAGE TODAY IS EXPECTED TO BE LESS THAN YESTERDAY...SCATTERED SHOWERS OVER THE ADJACENT ATLANTIC WATERS SPREADING ASHORE ACROSS PORTIONS OF THE EAST COAST AREAS EARLY THIS MORNING WILL REMAIN POSSIBLE ONCE AGAIN. THIS LINES UP WELL WITH THE LATEST HRRR AND WRF MODEL REFLECTIVITIES TODAY. FOR THE AFTERNOON...EXPECT THIS ACTIVITY TO SPREAD INLAND AND BECOME CONCENTRATED OVER THE INTERIOR AND WESTERN AREAS THROUGH THE EVENING HOURS BEFORE DIMINISHING. THE EASTERLY FLOW HAS WEAKENED COMPARED TO YESTERDAY...WHICH SHOULD ALLOW A WEST COAST SEA BREEZE TO BECOME ESTABLISHED THIS AFTERNOON. THE MAIN IMPACTS FROM THIS AFTERNOON/EVENING ACTIVITY WILL BE THE POTENTIAL FOR PERIODS WITH HEAVY RAIN AND GUSTY WINDS WITH ANY STRONGER STORMS THAT DEVELOP. HOWEVER...MODEL SOUNDINGS ARE NOT THAT IMPRESSIVE AND INDICATE MEAGER MID-LEVEL LAPSE RATES WITH NEAR AVERAGE 500 MB TEMPERATURES. OVER THE WEEKEND...SIMILAR CONDITIONS WILL BE EXPECTED EACH DAY WITH TEMPERATURES REMAINING NEAR OR AROUND NORMAL. .LONG TERM (SUNDAY NIGHT-THURSDAY)... MODELS CONTINUE TO INDICATE UPPER HEIGHTS FALLING AHEAD OF A SHORTWAVE TROUGH PROGGED TO TRANSLATE EAST THEN NORTHEAST ACROSS THE REGION WELL NORTHWEST OF OUR LOCAL AREA SUNDAY THROUGH TUESDAY. THIS SHORTWAVE COMBINED WITH ANOTHER POTENT PIECE OF ENERGY DIVING SOUTHEAST OVER THE PLAIN STATES WILL QUICKLY AMPLIFY THE OVERALL UPPER PATTERN ACROSS THE COUNTRY CHARACTERIZED WITH A DEEPENING TROUGH OVER THE EASTERN STATES AND RIDGING OUT WEST. THE ATTENDANT COLD FRONT ASSOCIATED WITH THE LEAD SHORTWAVE IS FORECAST TO SWEEP EAST ACROSS THE REGION AND GENERALLY LAYOUT FROM EAST TO WEST AND STALL JUST NORTH OF OUR LOCAL AREA SOMETIME AROUND THE MID-WEEK TIME FRAME AS IT LOSES ITS UPPER SUPPORT. THE ECMWF AND GFS/GFS ENSEMBLE MEAN SOLUTIONS APPEAR TO BE IN BETTER AGREEMENT WITH THIS BOUNDARY SPATIALLY AND TEMPORALLY THROUGH THIS...WHEREAS...24 HRS AGO INDICATED LARGER DIFFERENCES. IF THIS VERIFIES...EXPECT THE LOW-LEVEL FLOW LOCALLY TO GRADUALLY VEER TO THE SOUTH AND SOUTHWEST MONDAY THROUGH TUESDAY AS A WARM FRONT LIFTS NORTH OVER THE EASTERN GULF AND FL. THE RESULTANT DEEP AND MOIST SOUTHWEST FLOW SHOULD TRANSLATE TO HIGHER THAN NORMAL RAIN CHANCES...ESPECIALLY OVER THE NORTH AND NORTHEASTERN SECTIONS OF THE FORECAST AREA FROM THE LAKE TO PALM BEACH REGION. DUE TO THE BETTER AGREEMENT BETWEEN THE LATEST MODEL GUIDANCE AND PERSISTENCE FROM RUN TO RUN...WILL SLIGHTLY INCREASE THE RAINFALL PROBABILITIES MONDAY THROUGH THE MID-WEEK PERIOD. && .MARINE... LIGHT TO MODERATE EASTERLY WINDS AND WILL PERSIST THROUGH THE WEEKEND WITH SCATTERED SHOWERS AND STORMS POSSIBLE...ESPECIALLY OVERNIGHT AND THROUGH THE EARLY MORNING HOURS ACROSS THE ATLANTIC WATERS. SEAS WILL GRADUALLY TREND DOWN THROUGH THE WEEKEND TO AROUND NORMAL. WINDS ARE FORECAST TO SHIFT SOUTH AND POSSIBLY SOUTHWEST SOMETIME NEXT WEEK FROM MONDAY THROUGH WEDNESDAY AS ANOTHER FRONTAL BOUNDARY APPROACHES AND STALLS NORTH OF THE MARINE AREA. && .FIRE WEATHER... MOIST CONDITIONS WILL KEEP RH`S WELL ABOVE CRITICAL LEVELS THROUGH THE FORECAST PERIOD. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 86 77 86 76 / 30 20 30 20 FORT LAUDERDALE 86 78 88 78 / 20 20 30 20 MIAMI 87 78 88 78 / 30 20 40 20 NAPLES 89 74 91 75 / 30 30 40 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...85/AG AVIATION/RADAR...15/JR
AREA FORECAST DISCUSSION
NWS LINCOLN IL
217 AM CDT FRI SEP 14 2012 .DISCUSSION... ISSUED 217 AM CDT FRI SEP 14 2012 SHORT TERM...TODAY THROUGH SUNDAY BAND OF POST-FRONTAL PRECIPITATION CONTINUES TO SHIFT SLOWLY EASTWARD ACROSS CENTRAL ILLINOIS EARLY THIS MORNING. BASED ON SATELLITE/RADAR LOOPS...IT APPEARS SCATTERED LIGHT SHOWERS WILL BE CONFINED TO LOCATIONS ALONG AND SOUTH OF A DANVILLE TO TAYLORVILLE LINE BY 12Z/7AM. THIS PRECIP WILL GRADUALLY SETTLE SOUTH OF THE KILX CWA BY MID TO LATE MORNING...FOLLOWED BY CLEARING SKIES ACROSS THE BOARD BY AFTERNOON. WITH CLEARING OF LOW CLOUDINESS ALREADY TAKING PLACE NORTHWEST OF THE ILLINOIS RIVER...THE PROBLEM ACROSS THE FAR NORTHWEST CWA WILL LIKELY BE FOG THIS MORNING. 07Z/2AM OB FROM KGBG SHOWS 1/4SM VISBY...WITH WIDESPREAD 1/2 TO 1/4SM VISBYS ACROSS EASTERN IOWA AND NORTHWESTERN ILLINOIS. WILL MONITOR THIS AREA CLOSELY FOR A POTENTIAL DENSE FOG ADVISORY. AT THIS POINT...WILL INCLUDE AREAS OF FOG DURING THE EARLY MORNING ALONG AND WEST OF I-55...WITH AREAS OF DENSE FOG FURTHER NORTHWEST ACROSS KNOX AND STARK COUNTIES. ONCE THE FOG DISSIPATES AND THE SHOWERS ACROSS THE SE COME TO AN END...SUNNY SKIES AND DRY WEATHER WILL BE THE RULE ACROSS THE ENTIRE AREA THIS AFTERNOON. WITH HIGH PRESSURE BUILDING INTO THE REGION TONIGHT...CLEAR SKIES AND LIGHT WINDS WILL ALLOW EXCELLENT RADIATIONAL COOLING CONDITIONS TO DEVELOP. SINCE THERE WILL BE QUITE A BIT OF SUNSHINE AND MIXING THIS AFTERNOON...AND A VERY DRY AIRMASS IS ADVECTING IN FROM THE NORTHWEST...DO NOT THINK FOG WILL DEVELOP TONIGHT. INSTEAD...IT WILL BE A CLEAR AND VERY COOL NIGHT...WITH LOWS DIPPING INTO THE 40S. WITH SURFACE HIGH PRESSURE HOLDING FIRM THROUGHOUT THE WEEKEND...EXPECT DRY WEATHER BOTH SATURDAY AND SUNDAY. UPPER WAVE CURRENTLY NOTED ON WATER VAPOR IMAGERY OVER THE TEXAS PANHANDLE IS PROGGED TO SHIFT EASTWARD INTO THE TENNESSEE RIVER VALLEY SUNDAY NIGHT INTO MONDAY...HOWEVER IT APPEARS ANY PRECIP ASSOCIATED WITH THIS FEATURE WILL REMAIN SOUTH OF ILLINOIS. LONG TERM...MONDAY THROUGH THURSDAY THE MAIN STORY IN THE EXTENDED WILL BE THE COOL WEATHER NEXT WEEK...AS UPPER RIDGE BUILDS WEST OF THE ROCKIES AND DEEP TROUGH SETTLES IN ACROSS THE MIDWEST/GREAT LAKES. VIGOROUS SHORT-WAVE TROUGH WILL APPROACH FROM THE NORTHWEST ON MONDAY...PUSHING A COLD FRONT INTO CENTRAL ILLINOIS. BOTH THE GFS AND ECMWF ARE IN GOOD AGREEMENT CONCERNING THE TIMING OF THE FRONT...WITH BOTH MODELS SUGGESTING SCATTERED SHOWERS/STORMS MONDAY AFTERNOON AND EVENING. GFS BRINGS 60 TO 65F SURFACE DEWPOINTS NORTHWARD INTO THE AREA AHEAD OF THE ADVANCING FRONT MONDAY AFTERNOON. THIS RESULTS IN MODEST CAPE VALUES OF 500 TO 1000J/KG. STRONGEST 0-6KM SHEAR APPEARS TO LAG BEHIND THE FRONT...SO INSTABILITY/SHEAR PARAMETERS NEVER COINCIDE WITH ONE ANOTHER. AS A RESULT...AM EXPECTING MAINLY SHOWERS...WITH A FEW EMBEDDED THUNDERSTORMS AS THE FRONT PASSES. MODEL CONSENSUS TAKES BOUNDARY EAST OF ILLINOIS BY LATE MONDAY NIGHT...SO COOL/DRY WEATHER WILL RETURN ON TUESDAY. AIRMASS BEHIND FRONT WILL BE MUCH COOLER...WITH THE GFS SHOWING THE 0C 850MB ISOTHERM DIPPING INTO NORTH-CENTRAL ILLINOIS. THINK THIS MAY BE A BIT TOO COOL...BUT EVEN THE SLIGHTLY WARMER ECMWF SUGGESTS HIGH TEMPS WILL ONLY MAKE IT INTO THE MIDDLE TO UPPER 60S. AFTER A QUICK WARM-UP ON WEDNESDAY...ANOTHER SHORT-WAVE TROUGH AND ASSOCIATED COLD FRONT WILL APPROACH WEDNESDAY NIGHT. WILL CARRY A CHANCE FOR SHOWERS AS THE FRONT MOVES THROUGH...FOLLOWED BY ANOTHER SHOT OF COOL/DRY AIR FOR THE END OF NEXT WEEK. BARNES && .AVIATION... ISSUED 1145 PM CDT THU SEP 13 2012 A WEAKENING BAND OF LIGHT RAIN SHOWERS OVER CENTRAL IL FROM THE IL RIVER SE TO I-72 BEHIND A COLD FRONT (PRESSING INTO FAR SE IL LATE THIS EVENING) WILL GRADUALLY DIMINISH FROM NW TO SE DURING THE OVERNIGHT HOURS. LIGHT RAIN SHOWERS COULD BRING VSBYS DOWN TO 5-7 MILES AND CEILINGS AS LOW AS 1-2K FT OR BRIEFLY JUST BELOW 1K FT NEXT FEW HOURS. HI-RESOLUTION MODELS LIKE HRRR AND RUC13 HAVE SLOWED THE CLEARING OF THE CLOUDS OVERNIGHT AND IF THIS VERIFIES THEN FOG FORMATION IS LESS LIKELY LATER TONIGHT OVER CENTRAL IL. SCATTERED OUT MID LEVEL CLOUDS BETWEEN 10Z-15Z AND BRING MVFR VSBYS OF 3-5 MILES WITH FOG AT PIA WHICH IS SOONER TO SCATTER OUT. CLOUD COVER CURRENLY FAIRLY EXPANSIVE UPSTREAM OVER CENTRAL/SOUTHERN IA AND NORTHERN MO...SO DELAY IN CLEARING SEEMS REASONABLE. 1031 MB HIGH PRESSURE OVER NW KS AND RIDGING INTO SE IA/NW IL WILL WEAKEN TO 1026 MB AS IT SETTLES INTO CENTRAL IL DURING FRIDAY AFTERNOON AND BRING FAIR WEATHER WITH JUST FEW- SCATTERED CUMULUS CLOUDS MAINLY AT DEC AND CMI AND SCATTERED CIRRUS. CLEAR SKIES EXPECTED BY FRIDAY EVENING. NNE WINDS OF 5-10 KTS OVERNIGHT WILL BECOME LIGHT AND VARIABLY BY SUNSET FRIDAY. KH && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1147 PM CDT THU SEP 13 2012 .DISCUSSION... ISSUED 855 PM CDT THU SEP 13 2012 UPDATED THE FORECAST TONIGHT FOR SLOWER TRENDS WITH SHOWERS MOVING SOUTHEAST INTO CENTRAL/SOUTHEAST IL ALONG WITH SLOWER CLEARING OF THE CLOUDS FROM NW TO SE OVERNIGHT AND FRI MORNING. BUMPED UP LOWS A FEW DEGREES INTO THE UPPER 50S AND LOWER 60S OVER SOUTHEAST IL. COLD FRONT WAS OVER CENTRAL INDIANA INTO SOUTHEAST IL NEAR I-70 AND INTO SE MO TO WEAK 1018 MB LOW PRESSURE IN WEST CENTRAL AR. BAND OF SHOWERS BEHIND THE COLD FRONT ABOUT 100 MILES WIDE WAS OVER THE IL RIVER VALLEY AND HAS BEEN ONLY VERY SLOWLY MOVING TO THE SOUTHEAST. THE RAIN SO FAR THIS EVENING HAS BEEN MAINLY ALONG AND NW OF THE IL RIVER. TEMPERATURES RANGE FROM THE MID 50S NW OF THE IL RIVER TO THE LOWER 70S AHEAD OF THE COLD FRONT SE OF I-70. SO A TASTE OF FALL WEATHER LIES BEHIND THE COLD FRONT ACROSS CENTRAL IL RIGHT NOW. USED THE HRRR AND RUC13 MODELS TO TIME THE BAND OF RAIN SHOWERS PRESSING SE THROUGH CENTRAL IL TONIGHT...NOT REACHING SE IL UNTIL LATE TONIGHT INTO FRI MORNING. HAVE CLOUDS DECREASING ACROSS THE IL RIVER VALLEY AFTER 2 AM. CLOUDS CURRENTLY EXTEND UPSTREAM ACROSS CENTRAL/SE IOWA. NORTH WINDS OF 5 TO 15 MPH AND A FEW GUSTS NEAR 20 MPH EARLY TO DIMINISH UNDER 10 MPH DURING OVERNIGHT. THIS DUE TO 1029 MB HIGH PRESSURE OVER NORTHERN KS INTO SOUTHERN IA THAT NOSES INTO THE IL RIVER VALLEY FRI MORNING. KH && .AVIATION... ISSUED 1145 PM CDT THU SEP 13 2012 A WEAKENING BAND OF LIGHT RAIN SHOWERS OVER CENTRAL IL FROM THE IL RIVER SE TO I-72 BEHIND A COLD FRONT (PRESSING INTO FAR SE IL LATE THIS EVENING) WILL GRADUALLY DIMINISH FROM NW TO SE DURING THE OVERNIGHT HOURS. LIGHT RAIN SHOWERS COULD BRING VSBYS DOWN TO 5-7 MILES AND CEILINGS AS LOW AS 1-2K FT OR BRIEFLY JUST BELOW 1K FT NEXT FEW HOURS. HI-RESOLUTION MODELS LIKE HRRR AND RUC13 HAVE SLOWED THE CLEARING OF THE CLOUDS OVERNIGHT AND IF THIS VERIFIES THEN FOG FORMATION IS LESS LIKELY LATER TONIGHT OVER CENTRAL IL. SCATTERED OUT MID LEVEL CLOUDS BETWEEN 10Z-15Z AND BRING MVFR VSBYS OF 3-5 MILES WITH FOG AT PIA WHICH IS SOONER TO SCATTER OUT. CLOUD COVER CURRENLY FAIRLY EXPANSIVE UPSTREAM OVER CENTRAL/SOUTHERN IA AND NORTHERN MO...SO DELAY IN CLEARING SEEMS REASONABLE. 1031 MB HIGH PRESSURE OVER NW KS AND RIDGING INTO SE IA/NW IL WILL WEAKEN TO 1026 MB AS IT SETTLES INTO CENTRAL IL DURING FRIDAY AFTERNOON AND BRING FAIR WEATHER WITH JUST FEW- SCATTERED CUMULUS CLOUDS MAINLY AT DEC AND CMI AND SCATTERED CIRRUS. CLEAR SKIES EXPECTED BY FRIDAY EVENING. NNE WINDS OF 5-10 KTS OVERNIGHT WILL BECOME LIGHT AND VARIABLY BY SUNSET FRIDAY. KH && .PREV DISCUSSION... ISSUED 300 PM CDT THU SEP 13 2012 THE OVERALL PATTERN FOR THE NEXT 7 DAYS WILL BE FAVORABLE FOR COOLER THAN NORMAL TEMPS WITH PERIODIC RAINFALL CHANCES. A LONGWAVE TROUGH WILL DOMINATE THE UPPER LEVEL FLOW ACROSS EASTERN CANADA AND THE GREAT LAKES/NORTHEASTERN CONUS. THAT WILL SET THE STAGE FOR A SERIES OF WAVES ARRIVING ON NORTHWEST FLOW ALOFT. THE FIRST PERIOD OF RAIN WILL BE TONIGHT INTO FRIDAY MORNING...THE SECOND WILL BE MONDAY AND MONDAY NIGHT...WITH THE THIRD COMING NEXT WED NIGHT INTO THURSDAY. SHORT TERM...TONIGHT THROUGH SUNDAY. THE COLD FRONT ARRIVING INTO NW IL THIS AFTERNOON IS BEING SLOWED DOWN BY A SHORTWAVE LIFTING NORTH FROM TENNESSEE AND WESTERN KENTUCKY INTO SOUTHEAST ILLINOIS. SHOWERS ARE FEW AND FAR BETWEEN AT THE MOMENT...BUT RAIN SHOULD FILL IN THIS EVENING AS THE COLD FRONT GETS AN ENHANCE BOOST OF LIFT FROM THE DPVA FROM THE SHORTWAVE IN SOUTHEAST IL. WE KEPT OUR LIKELY POPS IN FOR THIS EVENING EVERYWHERE...THEN CONFINED THE LIKELY POPS TO SOUTHEAST OF I-55 AFTER MIDNIGHT. THE SLOWER NATURE OF THE FRONTAL PROGRESSION LED US TO CONTINUE WITH SOME LOW CHANCE POPS SOUTHEAST OF I-70 AND SLIGHT CHANCES UP TO PARIS/DANVILLE FOR FRIDAY MORNING. SOME LIGHT FOG MAY DEVELOP NORTHWEST OF THE IL RIVER LATE TONIGHT IF ANY CLEARING REACHES THAT AREA. THE SHORT RANGE MODELS ARE INDICATING SOME CLEARING AFTER 3 AM...SO FOG POTENTIAL WILL NEED TO BE WATCHED. CLEARING SHOULD PROGRESS FROM NW TO SE ON FRIDAY AS HIGH PRESSURE BUILDS INTO THE AREA. FORECAST SOUNDINGS SHOW MIXING HEIGHTS AND LOW LEVEL TEMPS SUPPORTIVE OF BELOW NORMAL HIGHS...WITH READINGS IN THE LOWER 70S ACROSS THE BOARD. NORTHERLY WINDS WILL ADD SOME CHILL TO THE AIR AS WELL. A PLEASANT WEEKEND IS ON TAP AS HIGH PRESSURE REMAINS IN CONTROL. WEAK RIDGING AND HEIGHT RISES ALOFT WILL AID IN SLIGHT WARMING OF HIGH TEMPS TO NEAR NORMAL FOR SATURDAY AND SUNDAY. HIGHS SHOULD REACH NEAR NORMAL IN THE MID TO UPPER 70S BOTH DAYS...WITH PLENTY OF SUNSHINE. LONG TERM...MONDAY THROUGH THURSDAY. MONDAY WILL FEATURE THE APPROACH OF THE NEXT COLD FRONT. THE AVERAGE TIMING OF THE FRONT IN THE EXTENDED MODELS PUTS THE RAINFALL INTO OUR NW COUNTIES BY MID MORNING ON MONDAY...AND CONTINUING INTO MONDAY NIGHT...ESPECIALLY SE OF I-55. A BREAK IN THE ACTION AND COOLER TEMPS ARE EXPECTED FOR TUESDAY. THE GFS EVEN BRINGS THE 0C LINE AT 850MB INTO NORTH CENTRAL IL TUESDAY AFTERNOON AND EVENING. THE ECMWF AND CANADIAN KEEP THE 0C LINE IN WISCONSIN/MICH...SO WE ARE TAKING THAT WILL A GRAIN OF SALT. HOWEVER...THE THEME WILL BE BELOW NORMAL TEMPS FOR TUE NIGHT/WED AND INTO THURSDAY. THE NEXT QUICK SHORTWAVE/COLD FRONT IS EXPECTED TO MOVE SE INTO OUR COUNTIES WED NIGHT. THE EC/GFS BOTH INDICATE THIS FEATURE PRETTY CLOSELY...SO WE KEPT THE ALLBLEND CHANCE POPS FOR THAT TIME FRAME. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
112 PM EDT FRI SEP 14 2012 .AVIATION... HIGH PRESSURE AND DRY AIR WILL CONTINUE TO FILTER INTO THE AREA BEHIND THE EXITING COLD FRONT. THIS WILL BRING VFR CONDITIONS THROUGH THE PERIOD. WINDS WILL BE LIGHT AND VARIABLE OVERNIGHT AS THE SURFACE HIGH SETTLES OVER THE REGION BUT FOG IS NOT EXPECTED TO BE A CONCERN GIVEN THE VERY DRY LOW LEVELS. && .PREV DISCUSSION... /ISSUED 413 AM EDT FRI SEP 14 2012/ SHORT TERM... PRIMARY POST FNTL RAIN BAND IN ASSOCN/W POTENT UPR TROUGH OVR NE MN TEMPORARILY IN THE PROCESS OF DECAY ACRS NW IN ATTM AS UPR SPEED MAX PULLS AWAY. HWVR UPSTREAM SAT OBS AND MOST RECENT RADAR DATA SHOW INTENSIFICATION/EXPANSION OF SECONDARY AREA OF RAINFALL ACRS CNTRL IL TIED TO SECONDARY UPR SPEED MAX WHICH 06Z RUC MODEL GUIDANCE LOOKS TO HAVE A GOOD HANDLE ON. 00Z GUIDANCE OUTSIDE GFS MUCH FASTER W/EWD EXIT OF PCPN BUT BASED ON RUC/GFS AND FURTHER SPC 4KM WRF WILL MAKE SOME SIG CHGS TO HOLD ONTO PCPN ACRS ERN IN FOR A BIT LONGER THROUGH 15Z. OTHERWISE SIG FNTL SURGE XPCD LTR TDA AS NRN STREAM SW OPENS FURTHER AND ACCELERATES INTO WRN QB BY LT AFTN. THUS CWA WILL SEE RAPID W-E CLRG AND SIG COLUMN DRYING AS DEEP SUBSIDENCE SOUTH OF MID LVL TROUGH SPREADS SEWD. DEEP MIXING AND INSOLATION WILL OFFSET EARLY LL CAA WING W/PRIOR GRIDDED MAX TEMPS CLOSE AND HELD. COOL CANADIAN SFC RIDGE FOLLOWS TONIGHT W/IDEAL RADIATIONAL COOLING XPCD. DEGREE OF DRYING XPCD THROUGH THIS AFTN WILL CURTAIL ANY LT NIGHT FOG THREAT W/MINS SETTLING INTO THE LOW-MID 40S. SFC RIDGE REMAINS ENTRENCHED ACRS THE AREA THROUGH SUN W/NO SENSIBLE WX CONCERNS. XPC SEASONABLE TEMPS W/SLIGHT WARMING TREND THROUGH THE WEEKEND. LONG TERM... SUNDAY THROUGH THURSDAY...THE UPPER LEVEL PATTERN OVER NORTH AMERICA WILL BECOME MORE AMPLIFIED THIS PERIOD AS SEVERAL SHORT WAVE TROFS MOVE RAPIDLY SOUTHEAST TOWARD THE GREAT LAKES REGION. THE 500 MB ANALOGS...GFS OPERATIONAL RUN AND THE BULK OF THE GFS ENSEMBLES ALL IN REASONABLE AGREEMENT WITH ONE ANOTHER THAT A LONG WAVE TROF WILL BECOME ESTABLISHED OVER EASTERN NORTH AMERICAN AND EXTEND ACROSS THE WESTERN GREAT LAKES REGION. THERE WILL BE BRIEF WARMUPS AHEAD OF EACH INDIVIDUAL TROF...SO TIMING OF THESE SMALLER SYSTEMS WITHIN THE MAIN TROF OUT SEVERAL DAYS A LITTLE TRICKY AT THIS POINT. HOWEVER...THE ONGOING TIMING OF THE FIRST 2 WAVES APPEARS ON TRACK IN REGARD TO THE LATEST MODEL RUNS MENTIONED ABOVE. HAVE MADE JUST SOME MINOR CHANGES...KEEPING A CHANCE FOR RAIN MONDAY NIGHT AND AGAIN THURSDAY. HAVE REMOVED RAIN CHANCES WEDNESDAY NIGHT TO TRY TO BECOME MORE REPRESENTATIVE WITH THE FORECAST. AS FOR TEMPERATURES...THE GFS/MEX APPEARS ON TRACK SUNDAY AND MONDAY...BUT THE GFS MEAN ENSEMBLE MOS APPEARS TOO COOL WITH HIGHS. HOWEVER...THE MEAN ENSEMBLE MOS DOES APPEAR ON TRACK TUESDAY THROUGH THURSDAY WITH HIGHS ONLY IN THE 60S. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...RIP CURRENT RISK THROUGH LATE TONIGHT FOR INZ003. MI...RIP CURRENT RISK THROUGH LATE TONIGHT FOR MIZ077. OH...NONE. LM...NONE. && $$ SHORT TERM...T LONG TERM...SKIPPER AVIATION...AGD
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
413 AM EDT FRI SEP 14 2012 .SHORT TERM... PRIMARY POST FNTL RAIN BAND IN ASSOCN/W POTENT UPR TROUGH OVR NE MN TEMPORARILY IN THE PROCESS OF DECAY ACRS NW IN ATTM AS UPR SPEED MAX PULLS AWAY. HWVR UPSTREAM SAT OBS AND MOST RECENT RADAR DATA SHOW INTENSIFICATION/EXPANSION OF SECONDARY AREA OF RAINFALL ACRS CNTRL IL TIED TO SECONDARY UPR SPEED MAX WHICH 06Z RUC MODEL GUIDANCE LOOKS TO HAVE A GOOD HANDLE ON. 00Z GUIDANCE OUTSIDE GFS MUCH FASTER W/EWD EXIT OF PCPN BUT BASED ON RUC/GFS AND FURTHER SPC 4KM WRF WILL MAKE SOME SIG CHGS TO HOLD ONTO PCPN ACRS ERN IN FOR A BIT LONGER THROUGH 15Z. OTHERWISE SIG FNTL SURGE XPCD LTR TDA AS NRN STREAM SW OPENS FURTHER AND ACCELERATES INTO WRN QB BY LT AFTN. THUS CWA WILL SEE RAPID W-E CLRG AND SIG COLUMN DRYING AS DEEP SUBSIDENCE SOUTH OF MID LVL TROUGH SPREADS SEWD. DEEP MIXING AND INSOLATION WILL OFFSET EARLY LL CAA WING W/PRIOR GRIDDED MAX TEMPS CLOSE AND HELD. COOL CANADIAN SFC RIDGE FOLLOWS TONIGHT W/IDEAL RADIATIONAL COOLING XPCD. DEGREE OF DRYING XPCD THROUGH THIS AFTN WILL CURTAIL ANY LT NIGHT FOG THREAT W/MINS SETTLING INTO THE LOW-MID 40S. SFC RIDGE REMAINS ENTRENCHED ACRS THE AREA THROUGH SUN W/NO SENSIBLE WX CONCERNS. XPC SEASONABLE TEMPS W/SLIGHT WARMING TREND THROUGH THE WEEKEND. && .LONG TERM... SUNDAY THROUGH THURSDAY...THE UPPER LEVEL PATTERN OVER NORTH AMERICA WILL BECOME MORE AMPLIFIED THIS PERIOD AS SEVERAL SHORT WAVE TROFS MOVE RAPIDLY SOUTHEAST TOWARD THE GREAT LAKES REGION. THE 500 MB ANALOGS...GFS OPERATIONAL RUN AND THE BULK OF THE GFS ENSEMBLES ALL IN REASONABLE AGREEMENT WITH ONE ANOTHER THAT A LONG WAVE TROF WILL BECOME ESTABLISHED OVER EASTERN NORTH AMERICAN AND EXTEND ACROSS THE WESTERN GREAT LAKES REGION. THERE WILL BE BRIEF WARMUPS AHEAD OF EACH INDIVIDUAL TROF...SO TIMING OF THESE SMALLER SYSTEMS WITHIN THE MAIN TROF OUT SEVERAL DAYS A LITTLE TRICKY AT THIS POINT. HOWEVER...THE ONGOING TIMING OF THE FIRST 2 WAVES APPEARS ON TRACK IN REGARD TO THE LATEST MODEL RUNS MENTIONED ABOVE. HAVE MADE JUST SOME MINOR CHANGES...KEEPING A CHANCE FOR RAIN MONDAY NIGHT AND AGAIN THURSDAY. HAVE REMOVED RAIN CHANCES WEDNESDAY NIGHT TO TRY TO BECOME MORE REPRESENTATIVE WITH THE FORECAST. AS FOR TEMPERATURES...THE GFS/MEX APPEARS ON TRACK SUNDAY AND MONDAY...BUT THE GFS MEAN ENSEMBLE MOS APPEARS TOO COOL WITH HIGHS. HOWEVER...THE MEAN ENSEMBLE MOS DOES APPEAR ON TRACK TUESDAY THROUGH THURSDAY WITH HIGHS ONLY IN THE 60S. && .AVIATION... POST FNTL RAIN BAND IN THE PROCESS OF RESURGING THIS MORNING IN ASSOCN/W SECONDARY UPR SPEED MAX PROGRESSING THROUGH BASE OF POTENT UPR TROUGH ROTATING THROUGH NE MN. KFWA HAS REMAINED ON ERN FRINGE OF MORE ISOLD ACTIVITY OVR NRN/NE IN BUT RAPID EXPANSION/INTENSIFICATION OF ECHOES SEEN UPSTREAM WOULD DICTATE EVENTUAL AMENDMENT TO CARRY A TEMPO MVFR VIS/CIG RESTRICTION THROUGH AT LEAST 12Z GIVEN NOD TWD SLWR RUC/GFS IMPLIED RAIN BAND PROGRESSION. REGARDLESS RAPID W-E DRYING XPCD INTO THIS AFTN AS UPR TROUGH OPENS AND ACCELERATES EWD INTO WRN QB BY EVENING. THUS OUTSIDE BRIEF PD OF MVFR CONDS EARLY THIS MORNING...VFR CONDS XPCD THROUGH THE REMAINDER OF THE TERMINAL FCST PD. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...RIP CURRENT RISK THROUGH LATE TONIGHT FOR INZ003. MI...RIP CURRENT RISK THROUGH LATE TONIGHT FOR MIZ077. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 8 AM EDT THIS MORNING FOR LMZ043-046. && $$ SHORT TERM...T LONG TERM...SKIPPER AVIATION...T
AREA FORECAST DISCUSSION
NWS DES MOINES IA
628 PM CDT SAT SEP 15 2012 ...UPDATED AVIATION DISCUSSION... .SHORT TERM /TONIGHT/... HIGH PRESSURE CENTERED OVER NORTHEAST MO WILL CONTINUE EAST WITH RETURN FLOW OF MORE MOIST AIR COMING AROUND THE BACK SIDE. THEREIN LIES THE PROBLEM FOR TONIGHT. HOW FAR TO BRING THE CLOUDS INTO SOUTHWEST IA AND THEN EVENTUALLY SPREADING THEM NORTHEAST. THE NAM/WRF AND EXPERIMENTAL SATELLITE PRODUCTS SEEM TO HAVE A PRETTY GOOD HANDLE ON IT AND WILL BRING CLOUDS TO JUST WEST OF OTTUMWA...THROUGH ABOUT AMES...TO FORT DODGE...THEN BACK TO DENISON. LOW TEMPS SUN SHOULD BE 5 TO 10 DEG WARMER THAN THIS MORNING. .LONG TERM /SUNDAY THROUGH SATURDAY/... THE COOLEST TEMPERATURES THUS FAR THIS SEASON WILL AFFECT OUR REGION BY THE MIDDLE OF THIS COMING WEEK...BUT NOT BEFORE A CHANCE OF RAINFALL SUNDAY NIGHT INTO MONDAY. SUNDAY IS A CHALLENGING DAY TO FORECAST...GIVEN THAT WE WILL BE IN THE TRANSITION ZONE BETWEEN A DEPARTING SFC HIGH AND THE APPROACHING NEXT WX SYSTEM. A LONG WAVE TROF WILL BRING THE NEXT WX SYSTEM TO OUR REGION...WITH BEST CHANCES OF PRECIP LATE SUNDAY NIGHT INTO MONDAY. MODELS HAVE BEEN TRENDING SLIGHTLY SLOWER WITH THIS SYSTEM. ALTHOUGH THE BEST FRONTOGENETICAL FORCING REMAINS NORTH OF IA-MN BORDER...PRECIP IS STILL EXPECTED IN OUR CWA. IN TERMS OF CONVECTION...ONLY ISOLATED TSRA ARE EXPECTED AT BEST. STRONG CAA BEHIND THIS SYSTEM WILL BRING OUR COOLEST TEMPS THUS FAR THIS SEASON TO OUR CWA MONDAY NIGHT. HAVE TRENDED SLIGHTLY COOLER ON MONDAY NIGHT/S LOWS FROM THE PREVIOUS FCST. PATCHY FROST WILL BE A POSSIBILITY IN OUR NORTHWESTERN CWA...GIVEN TEMPS IN THE MIDDLE 30S...ALONG WITH MINIMAL CLOUD COVER AND WIND. HAVE INSERTED PATCHY FROST WORDING THERE. TUESDAY WILL BRING RELATIVELY COOL TEMPS DURING THE DAYTIME TOO...AT LEAST ACROSS THE EASTERN HALF OF THE CWA...AS THE LONG WAVE TROF WILL BE SLOW TO LEAVE. TEMPS ARE A CHALLENGE...WITH THE POSSIBILITY OF THE WESTERN THIRD OF THE CWA SEEING A DECENT WARM UP ESPECIALLY IF THE CLOUDS MOVE OUT. REINFORCING SHOT OF COOL AIR WILL ARRIVE WEDNESDAY NIGHT INTO THURSDAY...IN CONJUNCTION WITH A POTENT SHORTWAVE DROPPING SOUTH FROM CANADA. MODELS SHOW CONSIDERABLE DIVERGENCE LATE IN THE FORECAST PERIOD AND BEYOND. ECMWF BRINGS ANOTHER LONG WAVE TROF SOUTH INTO THE NORTH CENTRAL U.S. FRIDAY NIGHT INTO SATURDAY...AND THEN ATTEMPTS TO DEVELOP A CLOSED H5 LOW OVER ARKANSAS BY SUNDAY NIGHT. THE GFS IS FASTER WITH THE LONG WAVE TROF...BRINGING IT INTO THE NORTH CENTRAL U.S. DURING THE DAY ON FRIDAY...AND THEN PUSHES IT TO OUR EAST WITHOUT A CLOSED LOW DEVELOPING. IF THE ECMWF WERE TO VERIFY THEN THE UNSETTLED WX MAY LINGER LONGER IN OUR AREA. && .AVIATION...16/00Z SURFACE HIGH CONTINUES TO SHIFT EAST WITH WEAK WAA LIKELY TO PERSIST THROUGH TOMORROW. KEPT WITH MENTION OF THE MVFR STRATUS DECK TO AFFECT DSM/FOD...JUST MOVED UP AN HOUR IN BOTH AREAS WITH HRRR A LITTLE QUICKER IN BRINGING IN THAN THE WRF. SOME MIXING DEVELOPS TOMORROW AFTERNOON WILL SEE SOME GUSTS IN THE UPPER TEENS AGAIN. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...MS SEP 12 LONG TERM...ZOGG AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
331 AM CDT FRI SEP 14 2012 .SHORT TERM /TODAY/... HIGH PRESSURE CONTINUES OVER SOUTHERN IOWA EARLY TODAY WITH A WEAK AREA OF LOW PRESSURE IN EASTERN SOUTH DAKOTA...INDUCED BY A POTENT H500 SHORT WAVE DROPPING SOUTH AND EAST AT THE BASE OF THE 500MB WESTERLIES EARLY TODAY. WITH LITTLE MOISTURE LEFT ACROSS THE NORTHERN PLAINS...LITTLE IMPACT FROM SHORT WAVE EXPECTED THIS MORNING. MEANWHILE...THE EXITING SYSTEM OF YESTERDAY CONTINUES TO BRING SOME HIGH CLOUDS TO SOUTHERN IOWA. TEMPS HAVE REACHED THE DEW POINT AND FOG HAS DEVELOPED...BUT SO FAR...WIDESPREAD FOG NOT A PROBLEM WITH THE CLOUD COVER. THE CLOUDS SOUTH WILL SLOWLY DEPART THROUGH EARLY MORNING WHILE THE WEAK TROUGH AND SFC LOW APPROACH FROM THE WEST. LIGHT SOUTHWEST WINDS ARE ANTICIPATED THROUGH MOST OF THE DAY WITH LITTLE MIXING TAKING PLACE THROUGH THE AFTERNOON HOURS. CONSEQUENTLY...A PLEASANT WARM AND DRY DAY IS EXPECTED WITH HIGHS IN THE UPPER 70S TO NEAR 80. DEW POINTS WILL REMAIN IN THE 40S FOR THE AFTERNOON KEEPING RH LEVELS FAIRLY LOW...BUT WITH LITTLE WIND ANTICIPATED...THE FIRE DANGER WILL NOT BE AMPLIFIED TODAY EVEN WITH LOWER RH VALUES THIS AFTERNOON. SKIES WILL REMAIN SUNNY THROUGH MOST OF THE AFTERNOON ONCE THE EARLY MORNING CLOUDS DEPART. .LONG TERM /TONIGHT THROUGH THURSDAY/... WEAK UPPER LEVEL NORTHWESTERLY FLOW WILL BE IN PLACE THROUGH THE WEEKEND. SURFACE WINDS WILL BE SOUTHERLY...AND WITH APPROACHING WAA FROM THE WEST AND GOOD CONDITIONS FOR MIXING...TEMPERATURES WILL WARM THROUGH THE WEEKEND. A FRONTAL BOUNDARY WILL PUSH SE ACROSS THE AREA SUNDAY NIGHT INTO MONDAY. AND HAVE KEPT POPS GOING...THOUGH HAVE TRENDED A BIT SLOWER ON SE EXTENT FOR SUNDAY NIGHT WITH PRECIPITATION FOCUSED BEHIND THE FRONT. HOWEVER...MODELS REMAIN IN GOOD AGREEMENT WITH SPEED OF SYSTEM...PUSHING IT THROUGH THE AREA QUICKLY...AND HAVE KEPT POPS OUT FOR MONDAY NIGHT...AS ANY RAIN CHANCES WILL BE WELL TO THE EAST. THIS BOUNDARY IS ASSOCIATED WITH A CANADIAN LOW PRESSURE SYSTEM...AND COLD CANADIAN AIR WILL PUSH IN BEHIND THE FRONT. TEMPERATURES WILL COOL SIGNIFICANTLY BEHIND THE BOUNDARY. NEWEST MODEL RUNS DROP H85 TEMPS OVER IOWA ANOTHER 2C OR SO OVER PAST RUNS...WITH TEMPS INT HE SINGLE DIGITS. HOWEVER...WARMER AIR WILL PUSH IN QUICKLY FROM THE WEST AHEAD OF ANOTHER LOW PRESSURES SYSTEM PUSHES EASTWARD ACROSS CANADA. THEREFORE...HAVE ONLY DROPPED TEMPS A FEW DEGREES FOR MONDAY NIGHT THROUGH TUESDAY NIGHT IN THE EAST. WITH THIS SECONDARY LOW PRESSURE SYSTEM FOR LATE IN THE PERIOD...COULD SEE ADDITIONAL CHANCES FOR PRECIPITATION. HOWEVER...DO NOT HAVE MUCH CONFIDENCE IN PRECIP CHANCES...AND HAVE CUT BACK ON POPS FOR WEDNESDAY AND THURSDAY. LOOKS LIKE BEST FORCING AND MOISTURE WILL REMAIN MUCH FURTHER NORTH...CLOSER TO CENTER OF LOW PRESSURE. && .AVIATION...14/06Z THIN LAYER OF HIGH CLOUDS REMAIN ACROSS THE SOUTHERN PORTION OF THE STATE AND HAVE ALLOWED FOR FOG DEVELOPMENT ACROSS SOME AREAS IN THE SOUTHEAST. KOTM LOOKS TO BOUNCE AROUND FROM MVFR TO LIFR VIS OVERNIGHT AND LATEST HRRR MODEL RUN HAS 1/4SM BY AROUND 10Z. WITH CURRENT OB AT LIFR...LIKELY WILL SEE IT DOWN MUCH SOONER. LOW CONFIDENCE WITH FOG DEVELOPMENT ELSEWHERE WITH STILL EITHER TOO STRONG OF WINDS OR NOT ENOUGH MOISTURE IN THE BOUNDARY FROM THE RAIN LAST EVENING. KALO WOULD LIKELY SEE THE BEST POTENTIAL OF FOG. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...REV LONG TERM...AWB AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1137 PM CDT THU SEP 13 2012 ...UPDATED AVIATION DISCUSSION... .SHORT TERM /TONIGHT/... MID LEVEL DRY AIR ADVECTION CONTINUES TO PUSH INTO CENTRAL IOWA THIS AFTERNOON AND HAS BEEN ERODING THE NORTHWEST EDGE OF THE DEPARTING PRECIPITATION BAND. THIS PRECIPITATION WILL BE SOUTHEAST OF THE FORECAST AREA BY 00Z. UPPER PV ANOMALY AND ASSOCIATED 500 MB LOW...WILL DIVE SOUTHEAST THROUGH MINNESOTA AND INTO THE WESTERN GREAT LAKES TONIGHT. IMPRESSIVE -26C 500 MB COLD CORE JUST NORTHEAST OF WHERE THE 1.5 PV PRESSURE DIPS TO BELOW 500 MB THROUGH THAT REGION. THE PRIMARY IMPACT WITH THIS SYSTEM WILL BE A FEW MID LEVEL CLOUDS PASSING THROUGH OVER THE NORTHEAST. A WEAK SFC LOW REFLECTION WILL MOVE SLOWLY SOUTHEAST OVERNIGHT AS WELL AND WILL HELP SWITCH SFC WINDS TO LIGHT SOUTHERLY AND HELP KEEP THE VERY LOW DEWPOINTS CURRENTLY OVER THE DAKOTAS AND MINNESOTA OUT OF THE STATE. THE COOL START THIS EVENING ALONG WITH THE CLEARING SKIES AND LIGHT WINDS WILL STILL ALLOW TEMPERATURES TO COOL QUICKLY JUST NOT AS MUCH AS IF THE VERY DRY AIR WAS IN PLACE. PASSING MID LEVEL CLOUDS OVER THE NORTHEAST WILL IMPACT DIURNAL TRENDS A BIT AND IF PERSIST LONG ENOUGH...MAY KEEP LOWS UP A FEW DEGREES. OVERALL EXPECT LOWS IN THE LOW TO MID 40S WITH A FEW UPPER 30S POSSIBLE OVER THE NISHNABOTNA VALLEY AND NORTHWEST. .LONG TERM /FRIDAY THROUGH THURSDAY/... MID LEVEL RIDGING WILL WORK INTO THE STATE ON FRIDAY...AS THE SURFACE HIGH SLOWLY PUSHES EAST OF THE AREA. SOUTH/SOUTHWESTERLY FLOW WILL DEVELOP ALONG THE BACKSIDE OF THE DEPARTING HIGH ON FRIDAY AFTERNOON. THE 13/12Z NUMERICAL MODELS ALL DEPICTED HIGHER WINDS WITHIN THE MIXED LAYER FRIDAY AFTERNOON...WHICH DESPITE THE RECENT RAINFALL...FULL SUNSHINE ALONG WITH ENHANCED MIXING SHOULD AID IN HIGHS REACHING THE UPPER 70S TO LOW 80S. AFTER A RELATIVELY BENIGN AND MILD WEEKEND...A RATHER STRONG WAVE AND ASSOCIATED COLD FRONT WILL APPROACH THE MIDWEST LATE SUNDAY INTO MONDAY. MODELS ARE STILL STRUGGLING WITH THE EXACT TRACK/TIMING OF THE DIGGING WAVE...WITH THE 13/12Z GFS DIGGING THE WAVE ACROSS EASTERN NE WHILE THE 13/12Z EURO DIVES IT ACROSS NORTHERN ILLINOIS. REGARDLESS OF THE EXACT TRACK...POSTFRONTAL PRECIPITATION LOOKS LIKE A PRETTY GOOD BET ACROSS THE CWA AS STRONG DYNAMIC FORCING AND MID LEVEL FRONTOGENESIS INTERACT WITH SUFFICIENT MID/LOW LEVEL MOISTURE. MOST SOUNDINGS DEPICT AT LEAST SOME ELEVATED INSTABILITY...SO HAVE KEPT ISOLATED THUNDERSTORMS IN THE FORECAST WITH THE WAVE PASSAGE. NORTHWEST FLOW DEVELOPS BEHIND THE DEPARTING SYSTEM FOR THE MIDDLE OF NEXT WEEK...WITH SEVERAL DISTURBANCES DROPPING THROUGH THE FLOW WHICH MAY PROVIDE SOME SHOWERS FOR THE MIDDLE OF NEXT WEEK. && .AVIATION 14/06Z... THIN LAYER OF HIGH CLOUDS REMAIN ACROSS THE SOUTHERN PORTION OF THE STATE AND HAVE ALLOWED FOR FOG DEVELOPMENT ACROSS SOME AREAS IN THE SOUTHEAST. OTM LOOKS TO BOUNCE AROUND FROM MVFR TO LIFR VIS OVERNIGHT AND LATEST HRRR MODEL RUN HAS 1/4SM BY AROUND 10Z. WITH CURRENT OB AT LIFR...LIKELY WILL SEE IT DOWN MUCH SOONER. LOW CONFIDENCE WITH FOG DEVELOPMENT ELSEWHERE WITH STILL EITHER TOO STRONG OF WINDS OR NOT ENOUGH MOISTURE IN THE BOUNDARY FROM THE RAIN LAST EVENING. ALO WOULD LIKELY SEE THE BEST POTENTIAL OF FOG. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...DONAVON AVIATION...PODRAZIK LONG TERM...DEITSCH
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
631 PM CDT SAT SEP 15 2012 ...UPDATED FOR AVIATION DISCUSSION... .SYNOPSIS... ISSUED AT 210 PM CDT SAT SEP 15 2012 IN THE HIGHER LEVELS OF THE ATMOSPHERE, THERE WAS A LIGHT 250MB JET FROM CENTRAL OLD MEXICO NORTHEAST THROUGH TEXAS AND OKLAHOMA TO THE EAST COAST OVER COASTAL NORTH CAROLINA. THE AVERAGE SPEED IN THIS JET WAS 60 KNOTS, WITH A SMALL PEAK JETLET AROUND 70 KNOTS DOWN IN THE WEST TEXAS PANHANDLE. IN THE NORTHEASTERN PART OF THE U.S., THERE WAS TROUGH WITH 90 KNOTS OF NORTHWEST WINDS ON THE WEST SIDE OF THE TROUGH, OVER THE NORTHEASTERN GREAT LAKES, THEN CURVING TO A 90 KNOT SOUTHERLY JET OVER EASTERN QUEBEC, CANADA. THE 500MB CHART SHOWED HIGH PRESSURE CENTERED OVER WESTERN UTAH STRETCHING EAST THROUGH KANSAS, WITH AN UPPER LOW OVER QUEBEC AND ANOTHER OVER THE GULF OF MEXICO. THE 700MB PATTERN WAS SIMILAR TO THE 500MB LEVEL, WITH A NORTHEAST WIND AT DDC OF 05 KNOTS AND A 700MB TEMP OF +05. THE 850MB ANALYSIS SHOWED A WEALTH OF MOISTURE MOVING NORTHEASTWARD FROM THE TEXAS GULF COAST TO CENTRAL AND EASTERN KANSAS. A WARM FRONT WAS TO OUR NORTH, FROM SOUTHERN SASKATCHEWAN TO THE EASTERN DAKOTAS TO SOUTH CENTRAL NEBRASKA. A COLD FRONT WAS EVIDENT FROM AN 850MB LOW PRESSURE CENTER OVER CENTRAL OKLAHOMA SOUTHWESTWARD TO WEST TEXAS AND THEN WEST TO A LOW OVER WESTERN MEXICO. && .SHORT TERM...(THIS EVENING THROUGH TOMORROW) ISSUED AT 210 PM CDT SAT SEP 15 2012 FOR TONIGHT, HIGH PRESSURE OVERHEAD WILL ALLOW CLEAR OR CLEARING SKIES, LIGHT SOUTHEAST WINDS IN OUR CENTRAL AND EAST, BUT A TROUGH IN COLORADO SHOULD TURN WINDS LIGHT SOUTHWEST IN OUR WESTERN COUNTIES. ALTHOUGH ONLY 5 TO 10 MPH SOUTHWEST WINDS WILL BE OVER OUR WESTERN COUNTIES, THINK THE UPSLOPE FLOW AFFECT WILL HELP TEMPERATURES FROM FALLING AS PREVIOUSLY FORECAST. I RAISED MINIMUM TEMPERATURES IN OUR CENTRAL AND WEST, WHICH NOW FIT BETTER WITH OUR ISC NEIGHBORS. REVIEWED LAST NIGHT LOWS, WITH GCK AND HYS BOTTOMING OUT AT 41F, AND THINK THEY SHOULD BE NEAR THAT LEVEL IN THE WEST TONIGHT. ALL MODEL GUIDANCE IS EVEN HIGHER, IN THE MID 40S OUT WEST, BUT DID NOT WANT TO SEE-SAW BACK AND FORTH TOO MUCH. IN THE NEARER TERM, THE NAM AND HRRR MODELS BOTH PRODUCED A LITTLE LIGHT RAIN IN MY EXTREME SOUTHEAST BY 19Z TODAY. SINCE THIS HAS NOT MATERIALIZED, DECIDED TO LEAVE POPS OUT OF OUR SOUTHEAST COUNTIES SUCH AS COMANCHE AND BARBER. SUNDAY WILL SEE THE SURFACE TROUGH IN OUR WESTERN COUNTIES, PERHAPS AS FAR EAST AT KEARNY, GRANT AND STEVENS COUNTIES. WINDS WILL SHIFT SOUTH AND BY AFTERNOON INCREASE INTO THE 12 TO 15 MPH RANGE, GUSTING TO NEAR 20 MPH. THIS SOUTH WIND WILL AID IN TRANSPORTING WARMER AIR INTO SOUTHWESTERN KANSAS, ALLOWING MAXIMUM TEMPERATURES TO WARM APPROXIMATELY 10F DEGREES MORE THAN TODAY. SUNDAY`S HIGHS SHOULD RANGE FROM 84F IN HAYS AND DODGE CITY TO 89F IN SYRACUSE. HIGH PRESSURE ALOFT OVER THE PLAINS WILL STILL KEEP A LOT OF SUNSHINE OVERHEAD, WHICH WILL ALSO AID IN WARMING UP THE SURFACE. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 218 PM CDT SAT SEP 15 2012 AN UPPER LEVEL TROUGH WILL EXIT CANADA AND MOVE SOUTHEAST ACROSS THE NORTHERN PLAINS SUNDAY NIGHT AND MONDAY. AS THIS SYSTEM CROSSES THE NORTHERN PLAINS A COLD FRONT WILL MOVE ACROSS WESTERN KANSAS. PRECIPITATION CHANCES WITH THIS COLD FRONT AT THIS TIME STILL APPEARS SMALL. IF PRECIPITATION DOES OCCUR IT WILL BE ON MONDAY AS THE UPPER TROUGH CROSSES PORTIONS OF NORTH CENTRAL KANSAS. ANOTHER AREA WHERE A FEW SHOWERS OR EVEN A THUNDERSTORM MAY DEVELOP WILL BE IN FAR SOUTHWEST KANSAS NEAR THE LEFT EXIT REGION OF AN UPPER LEVEL JET. GIVEN THE EXPECTED CLOUD COVER AND THE COOLING THAT IS FORECAST BEHIND THIS FRONT IN THE 925-850MB LEVEL WILL TREND HIGHS DOWN A COUPLE OF DEGREES AND FAVOR THE COOLEST MODEL GUIDANCE. HIGHS MONDAY MAY STRUGGLE TO REACH THE UPPER 60S ACROSS PORTIONS OF WESTERN AND NORTH CENTRAL KANSAS. GUSTY NORTH WINDS WILL DEVELOP BEHIND THIS FRONT EARLY MONDAY. NAM MEAN MIXED LAYER WINDS SUGGESTING SUSTAINED WIND SPEEDS OF 30 TO 35 MPH AT 15Z AND 18Z MONDAY. GFS WAS A LITTLE WEAKER WITH THESE MIXED LAYER WINDS BUT GIVEN THE MAGNITUDE OF THE COLD AIR ADVECTION DEVELOPING EARLY MONDAY WILL LEAN TOWARDS THE STRONGER NAM WINDS AT THIS TIME. BY MONDAY NIGHT THE UPPER LEVEL TROUGH WILL MOVE EAST OF THE AREA AS AN AREA OF HIGH PRESSURE AT THE SURFACE BEGINS TO SETTLE INTO KANSAS. SKIES MAY BE CLEAR EARLY BUT BASED ON THE GFS AND ECMWF SOME 700MB MOISTURE AND WARM AIR ADVECTION IMPROVES DURING THE OVERNIGHT HOURS ACROSS WESTERN KANSAS. GIVEN LIGHT WINDS AND DEWPOINT IN THE UPPER 30S TO LOWER 40S WILL FAVOR THE COOLER GUIDANCE FOR OVERNIGHT TEMPERATURES BUT AM RELUCTANT TO GO MUCH LOWER THAN THE MID 40S GIVEN THE POTENTIAL FOR SOME CLOUD COVER TOWARDS DAYBREAK. ON TUESDAY A TROUGH OF LOW PRESSURE A THE SURFACE WILL DEVELOP ALONG THE LEE OF THE ROCKIES AS A NORTHWEST FLOW PERSISTS. 850MB TEMPERATURE TRENDS TUESDAY AND WEDNESDAY CONTINUES TO SUPPORT HIGHS REBOUNDING BACK INTO THE 80S. THIS WARM UP HOWEVER WILL BE SHORT LIVED AS ANOTHER COLD FRONT IS FORECAST TO MOVE SOUTH ACROSS THE CENTRAL PLAINS WEDNESDAY NIGHT OR EARLY THURSDAY. NOT ONLY WILL THIS FRONT BRING COOLER TEMPERATURES BACK TO WESTERN KANSAS BUT THERE MAY ALSO BE A SLIGHT CHANCE FOR THUNDERSTORMS AS WELL AS ANOTHER UPPER LEVEL TROUGH CROSSES THE NORTHERN PLAINS. AT THIS TIME MODELS APPEAR TO BE STRUGGLING WITH THE TRACK AND STRENGTH OF THIS NEXT UPPER LEVEL SYSTEM. CONFIDENCE IS NOT HIGH ON WHICH MAY BE MORE CORRECT SO WILL STAY CLOSE TO CONSENSUS FROM THE CREXTENDFCST_INT. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 626 PM CDT SAT SEP 15 2012 SURFACE HIGH PRESSURE WILL SLOWLY MOVE TO THE EAST INTO MISSOURI. A TROUGH OF LOW PRESSURE WILL DEVELOP IN THE LEE OF THE ROCKIES, RESULTING IN AN INCREASE IN SOUTH WINDS FROM 6 KTS TONIGHT TO AROUND 10-12KTS BY 16Z SUNDAY. WITH THE LACK OF LOW LEVEL MOISTURE, VFR CONDITIONS WILL PERSIST. && .PRELIMINARY POINT TEMPS/POPS... DDC 53 84 51 67 / 0 0 10 10 GCK 51 87 51 67 / 0 0 10 10 EHA 51 87 53 68 / 0 0 10 20 LBL 50 86 54 68 / 0 0 0 20 HYS 53 85 50 67 / 0 0 10 20 P28 57 85 57 77 / 0 0 10 20 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BURKE SHORT TERM...BURKE LONG TERM...BURGERT AVIATION...FINCH
AREA FORECAST DISCUSSION
NWS WICHITA KS
1157 PM CDT THU SEP 13 2012 .AVIATION...06Z TAFS KRSL/KSLN/KHUT/KICT/KCNU PER RECENT OBSERVATIONAL AND MODEL TRENDS...RAIN AND LOW MVFR/HIGH IFR CIGS SHOULD CONTINUE THROUGH ABOUT 08-10Z FOR KICT...AND THROUGH ABOUT MID MORNING FOR KCNU...AS MID-LEVEL CONVERGENCE ZONE SLOWLY SHIFTS SOUTHEAST. CIGS SHOULD RISE DRAMATICALLY AT KICT ONCE THE PRECIPITATION SHIELD SHIFTS SOUTHEAST OF THE TERMINAL. OTHERWISE...COULD SEE SCATTERED PRECIPITATION AND MVFR CIGS ENCROACH ON KCNU-KICT ONCE AGAIN BY LATER FRIDAY AFTERNOON/EVENING...AS LOW/MID LEVEL CONVERGENCE ZONE SHIFTS BACK NORTH. ADK && .PREV DISCUSSION... /ISSUED 919 PM CDT THU SEP 13 2012/ UPDATE... PER THE LATEST NAM...RUC AND HRRR MODELS...ANTICIPATING BEST RAIN CHANCES SLOWLY SHIFTING INTO FAR SOUTHERN/SOUTHEAST KS AS THE NIGHT PROGRESSES...AS 700-600MB CONVERGENCE ZONE SLOWLY SHIFTS SOUTH OVERNIGHT. THINKING BEST CHANCES AFTER MIDNIGHT WILL BE GENERALLY SOUTH OF A LINE EXTENDING FROM KINGMAN-WICHITA-EMPORIA. THIS AREA WILL BE CO-LOCATED UNDERNEATH BEST ZONE OF UPPER DIFFLUENCE. AREAS OF RAIN SHOULD CONTINUE TO LINGER THROUGH FRIDAY MORNING...WITH CHANCES REMAINING ALONG OK/KS BORDER THROUGH FRIDAY AFTERNOON. CONSEQUENTLY...FRIDAY TEMPERATURES WILL ONCE AGAIN BE COOLISH OVER FAR SOUTHERN KS. ADK PREV DISCUSSION... /ISSUED 643 PM CDT THU SEP 13 2012/ AVIATION...00Z TAFS KRSL/KSLN/KHUT/KICT/KCNU A RAINY AND CLOUDY 12-18 HOURS IS ANTICIPATED FOR PRIMARILY KICT AND KCNU...WITH KHUT ON THE NORTHERN FRINGE OF THE PRECIPITATION/CLOUDS...AS A MID-LEVEL CONVERGENCE ZONE REMAINS NEARLY STATIONARY OVER THE REGION. THE ONLY CHANCE OF ISOLATED THUNDER WILL BE FOR KCNU WHERE MARGINAL INSTABILITY WILL BE PRESENT. OTHERWISE...PREVAILING VSBYS IN -RA WILL LIKELY BE P6SM...WITH PERIODIC MVFR VSBYS IN RA. MVFR CIGS WILL PREVAIL AT KICT-KCNU THROUGH THE PERIOD. ONLY HAVE PREVAILING VCSH AND BKN030 AT KICT FROM 06Z ONWARD...ALTHOUGH MAY EVENTUALLY NEED TO AMEND THIS TO INCLUDE PREVAILING -RA AND CIGS BELOW 2000 FT AGL THROUGH AT LEAST THE PREDAWN HOURS. WILL CONTINUE TO MONITOR TRENDS. ADK PREV DISCUSSION... /ISSUED 311 PM CDT THU SEP 13 2012/ DISCUSSION... MAIN FORECAST CHALLENGE IS THE PROGRESSION OF PRECIPITATION TODAY AND TOMORROW AND THEN TEMPERATURES THROUGH SATURDAY. SYNOPSIS: THE UPPER WAVE HAS PROGRESSED EASTWARD WITH THE MAIN ENERGY LAGGING A BIT BEHIND. PRECIPITATION CONTINUES AHEAD OF THE MAIN ENERGY ACROSS THE EASTERN PORTIONS OF KANSAS THIS AFTERNOON. THE SURFACE FRONT HAS CHARGED SOUTHWARD AND IS SITUATED FROM MISSOURI SOUTHWESTWARD TO SOUTHWEST TEXAS. SCATTERED SHOWERS AND CLOUD COVER IN ADDITION TO THE COLD AIR ADVECTION HAVE KEPT TEMPERATURES COOL TODAY...WITH MOST LOCATIONS STAYING IN THE MID TO UPPER 50S TO LOW 60S. TONIGHT - SUNDAY: LIGHT SHOWERS WITH ISOLATED THUNDER WILL CONTINUE TO PROGRESS SOUTHEASTWARD ACROSS THE AREA TONIGHT. THE UPPER ENERGY THAT IS MOVING IN FROM NEW MEXICO WILL CONTINUE TO IMPACT THE REGION THROUGH THE WEEKEND...CAUSING IT TO BE A LITTLE COOLER AND CLOUDIER THAN PREVIOUSLY EXPECTED. AS THIS ENERGY TRANSLATES EASTWARD...THE LOWER LEVELS WILL RESPOND WITH MOIST RETURN FLOW ACROSS EASTERN KANSAS. EXPECT FRIDAY TO BE WARMER THAN TODAY...BUT STILL BELOW NORMAL WITH HIGHS IN THE UPPER 60S TO 70S. THE WARMEST TEMPERATURES WILL BE ACROSS CENTRAL KANSAS WHERE CLOUD COVER WILL BE MINIMAL AND INSOLATION WILL BE GREATER. THE REAL QUESTION IS HOW FAR NORTH THE CLOUD COVER WILL REMAIN THROUGH FRIDAY. EXPECTING THERE TO BE A FINE LINE BETWEEN CLOUDY AND SUNNY. TEMPERATURES UNDER THE CLOUD COVER AND POSSIBLE PRECIPITATION ARE EXPECTED TO BE IN THE 60S. BOUNDARY LAYER MOISTURE IS EXPECTED TO CONTINUE TO SURGE NORTHWARD ACROSS EASTERN KANSAS SATURDAY. THE CURRENT GUIDANCE (NAM/GFS/ECMWF) INDICATES THAT MOST OF CENTRAL AND EASTERN KANSAS WILL BE SOCKED IN UNDER LOW LEVEL CLOUDS. BECAUSE OF THIS HAVE TRENDED COOLER FOR TEMPERATURES ON SATURDAY. FEEL THAT WIDESPREAD TEMPERATURES IN THE 60S ARE NOT OUT OF THE QUESTION IF LOW CLOUDS ARE PRESENT AS ADVERTISED. CONFIDENCE ON PRECIPITATION THROUGH FRIDAY AND SATURDAY IS NOT OVERLY HIGH...BUT FEEL THE CHANCES REMAIN FOR SCATTERED LIGHT SHOWERS THROUGH MUCH OF THE DAY BOTH DAYS ACROSS EXTREME SOUTHERN AND EASTERN KANSAS. EXPECTING SUNDAY TO WARM UP AND DRY OUT AS THE UPPER ENERGY TRANSLATES MOSTLY EAST OF THE AREA. MONDAY - THURSDAY: THE NEXT WAVE WILL APPROACH FOR MONDAY AND WILL HELP KICK THE UPPER ENERGY EAST THAT PLAGUED THE AREA FOR THE WEEKEND. THIS WAVE WILL DRAG YET ANOTHER FRONT THROUGH DURING THE DAY MONDAY. THE GUIDANCE DOES INDICATE THAT SOME PRECIPITATION WILL DEVELOP ALONG THE FRONT...BUT CONFIDENCE ON THAT IS LOW. FEEL THE BEST CHANCES WILL REMAIN EAST AS THE FRONT IMPACTS THE BETTER MOISTURE. TEMPERATURES WILL AGAIN TAKE A HIT POST-FRONTAL AS SURFACE HIGH PRESSURE BUILDS IN. A REINFORCING SHOT OF COLD AIR WILL PUSH THROUGH ON THURSDAY AS THE NEXT PIECE OF ENERGY ROTATES AROUND THE UPPER TROUGH. THE EARLIER FRONTS WILL HELP TO PUSH MOISTURE FROM THE AREA...AND THIS FRONTAL PASSAGE IS LARGELY EXPECTED TO BE DRY. BILLINGS AVIATION...18Z TAFS KRSL/KSLN/KHUT/KICT/KCNU WIDESPREAD SHOWERS CONTINUE TO IMPACT MUCH OF SOUTH CENTRAL AND CENTRAL KANSAS AND WILL SPREAD SLOWLY EAST-SOUTHEAST THROUGH THE AFTERNOON. MVFR CIGS ARE EXPECTED TO PREVAIL FOR THE KICT/KHUT TAF SITES FOR MOST OF THE DAYLIGHT HOURS. WILL SEE LOWER CIGS AND LIGHT RAIN BEGIN TO IMPACT SOUTHEAST KANSAS AFTER 22Z. MVFR CIGS MAY CONTINUE WITHIN AREAS OF LIGHT RAIN THROUGH MUCH OF THE NIGHT OVER SOUTHEAST KANSAS WITH MORE UNCERTAINTY FURTHER WEST ACROSS SOUTH CENTRAL KANSAS. VFR CONDITIONS ARE EXPECTED TO RETURN TO CENTRAL KANSAS LATER THIS AFTERNOON AS A SFC RIDGE OF HIGH PRESSURE BUILDS INTO THE AREA SCOURING OUT THE LOW LEVEL MOISTURE. KETCHAM && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 53 70 54 73 / 100 30 10 10 HUTCHINSON 52 71 51 74 / 40 10 10 10 NEWTON 52 72 53 72 / 70 20 10 10 ELDORADO 52 70 52 71 / 100 30 10 20 WINFIELD-KWLD 54 69 56 75 / 100 50 20 20 RUSSELL 47 73 48 75 / 0 10 0 0 GREAT BEND 48 72 49 74 / 0 10 0 0 SALINA 48 74 50 73 / 0 10 0 10 MCPHERSON 51 72 51 74 / 30 10 0 10 COFFEYVILLE 56 67 59 70 / 90 50 20 30 CHANUTE 54 70 56 70 / 90 50 20 20 IOLA 54 70 56 70 / 80 40 20 20 PARSONS-KPPF 55 68 56 70 / 80 50 20 30 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
534 PM EDT FRI SEP 14 2012 .SYNOPSIS... SHOWERS WILL COME TO AN END THIS EVENING AS A COLD FRONT PUSHES EAST OF THE AREA. DRY AND COOL CONDITIONS WILL FOLLOW WITH HIGH PRESSURE BUILDING OVER THE AREA FOR THE WEEKEND. && .NEAR TERM /THROUGH SATURDAY/... 21Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO ACCOUNT FOR THE LATEST COLD FRONT POSITION AS IT CROSSES OUR AREA. RADAR, OBS, AND SAT IMAGERY INDICATE THAT A COLD FRONT HAS PUSHED EAST OF THE PITTSBURGH METRO AND CURRENTLY EXTENDS ALONG A LINE FROM DUBOIS TO WASHINGTON TO NEW MARTINSVILLE. SHOWERS HAVE BEEN LIMITED ALONG THE FRONT, WITH THE MORE MOISTURE STARVED PRE- FRONTAL ENVIRONMENT SOUTH OF PITTSBURGH LIMITING COVERAGE TO JUST ISOLATED SHOWERS. NORTHWARD OF KPIT, SHOWERS ARE MORE NUMEROUS WITH BETTER FORCING FROM 500MB POSITIVE VORTICITY ADVECTION AS A VORT LOBE PASS FROM NE OHIO INTO WESTERN PA. A NOTICEABLE 5-10 DEGREE DECREASE IN TEMPERATURES ALONG WITH A SOUTHWEST TO NORTHWEST WIND SHIFT WITH THE FRONTAL PASSAGE. TONIGHT...RADAR TRENDS ALONG WITH THE HRRR SUPPORT THE FRONT PUSHING EAST OF THE RIDGES BY 00Z WITH ANY LINGERING SHOWERS COMING TO AN END BY 03Z. BEHIND THE FRONTAL BAND OF MOISTURE, DRIER AIR IN THE 900-250MB LAYER WILL ADVECT INTO THE AREA AND ALLOW FOR CLEARING SKIES ACROSS THE AREA BY DAWN. HIGH PRESSURE WILL THEN BEGIN TO BUILD IN FROM THE WEST AND BECOME CENTERED ACROSS IN/OH BY DAWN. DESPITE CLEARING SKIES, LOOSENING PRESSURE GRADIENT WILL STILL BE ENOUGH FOR 5-10KT WINDS WHICH WILL PREVENT THE DEVELOPMENT OF FOG NEAR DAWN. TEMPS WILL STEADILY DROP OFF IN COLD AIR ADVECTION OVERNIGHT WITH LOWS NEAR LAMP GUIDANCE, RANGING FROM THE UPPER 40S TO THE LOWER 50S ACROSS THE AREA. SATURDAY...DESPITE RELATIVELY LOW CONVECTIVE TEMPS UNDR NW FLOW ALOFT...LOW INVERSION LEVELS SHOULD PRECLUDE ANY SHRA ON SATURDAY...ALTHOUGH CU/SC FIELD IS ANTICIPATED. TEMPS WERE FORECAST USING NAM NMBRS. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... DRY WX WL CONT THROUGH SUNDAY WITH BUILDING HIGH PRES. BY MONDAY...SHRTWV MOVG THRU THE BASE OF ADVNG LONGWAVE TROF IS FORECAST TO PULL MSTR NWD ALNG THE APPALACHIANS. AS THE SYSTEM IS STILL PROJECTED AS AN OPEN MID LVL WAVE...WWD EXTENT OF THE RESULTING PCPN IS QNABLE...AND LIKELY P0PS IN THE LATE DAY WERE CONFINED TO THE RIDGES FOR NOW. SHORT TERM TEMPS WERE FORECAST ABOUT 5 DEGREES UNDR THE AVERAGES USING TWEAKED NAM GUIDANCE. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... MODELS HAVE COME TO A MUCH BETTER CONSENSUS ON THE OVERALL PROGRESSION OF THE LONGWAVE TROUGH AND THE EMBEDDED WAVE OUT AHEAD OF IT THROUGH THE FIRST HALF OF THE PERIOD. THE ECMWF HAS FINALLY COME ON BOARD WITH THE GFS WITH A BIT MORE AMPLIFIED SYSTEM MOVING ALONG THE APPALACHIANS BRINGING PRECIPITATION NORTHWARD MONDAY NIGHT. THE DIFFERENCE COMES IN TIMING OF THE COLD FRONT WITH THE ECMWF ONLY SLIGHTLY SLOWER. WILL INTRODUCE LIKELY POPS STARTING MONDAY NIGHT THROUGH MUCH OF TUESDAY WITH BETTER MODEL AGREEMENT. NORTHWEST FLOW AND WHAT APPEARS TO BE THE COOLEST TEMPERATURES ALOFT SO FAR THIS SEASON WILL KEEP TEMPERATURES WELL BELOW NORMAL WEDNESDAY. THE DETERMINISTIC MODELS MAINTAIN A LONGWAVE TROUGH WITH EMBEDDED WAVES IN THE FLOW THURSDAY AND FRIDAY WHICH COULD BRING ROUNDS OF PRECIPITATION AND NEAR NORMAL TEMPERATURES FOR THE REMAINDER OF THE WEEK. && .AVIATION /21Z FRIDAY THROUGH WEDNESDAY/... THE COLD FRONT IS PUSHING ACROSS WESTERN PA AND WILL MOVE EAST OF THE MOUNTAIN RIDGES THIS EVENING. A PERIOD OF LOWER IFR/MVFR CEILINGS CAN BE EXPECTED FOR SEVERAL HOURS BEHIND THE COLD FRONT. SHOWERS AND LIGHT RAIN CAN EXPECTED BEHIND THE FRONT AS WELL WITH LITTLE RISK OF THUNDER. NORTHWEST WIND GUSTS OF 25 TO 30 KNOTS CAN BE EXPECTED IMMEDIATELY BEHIND THE COLD FRONT WITH DIMINISHING WINDS INTO MIDNIGHT. ONCE HIGH PRESSURE BUILD IN BEHIND THE FRONT SKIES SHOULD GENERALLY CLEAR OUT TOWARD THE EARLY MORNING. SOME PATCHY MORNING FOG IS POSSIBLE IN THE RIVER VALLEYS SATURDAY MORNING BUT IF WINDS REMAIN ABOVE 5 TO 10 KNOTS FOG WILL BE UNLIKELY. .OUTLOOK /SATURDAY THROUGH TUESDAY/... VFR CONDITIONS ARE EXPECTED UNDER HIGH PRESSURE SATURDAY THROUGH THE FIRST HALF OF MONDAY. THE NEXT CHANCE FOR SHOWERS AND RESTRICTIONS WILL BE WITH THE APPROACH OF A LOW PRESSURE SYSTEM AND COLD FRONT MONDAY NIGHT AND TUESDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
315 PM EDT FRI SEP 14 2012 .SYNOPSIS... DRY CONDITIONS AND SEASONABLE TEMPERATURES WILL CONTINUE AS HIGH PRESSURE REMAINS ACROSS THE MID ATLANTIC THROUGH TONIGHT. A WEAK COLD FRONT WILL TRACK ACROSS THE AREA SATURDAY MORNING. HIGH PRESSURE WILL RETURN SUNDAY BEFORE UNSETTLED WEATHER EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... A TOUCH MORE HUMID ACRS THE FA THIS AFTN AS COMPARED TO PAST FEW. SFC HI PRES CONTS TO WEAKEN THROUGH THE EVE HRS...WHILE CDFNT APPROACHES FM THE NW. SO FAR...LTL MOVEMENT (N) NOTED ON SCT SHRAS OVR ECNTRL NC THIS AFTN...17Z/14 RUC KEEPS THOSE SHRAS GENLY FM ALBEMARLE SND ON S...OTRW XPCG CLR-PCLDY WX E...AND P/MCLDY W. PCPN CURRENTLY ASSOCIATED W/ THE CDFNT HAS CONTD TO DIMINISH...APRS THAT HIGHEST PROB FOR ANY SHRAS AND MOST WIDESPREAD CLDNS WILL RMN NNW OF THE FA THROUGH TNGT. CDFNT TO PRESS INTO THE CNTRL PORTION OF FA BY 12Z/15. WILL HAVE POPS AOB 14% OVR THE FA OVRNGT. && .SHORT TERM /SATURDAY THROUGH MONDAY/... CDFNT PRESSES S AND E OF THE FA DURG SAT MRNG...W/ ASSOCIATED WINDSHIFT TO THE N AS SFC HI PRES BUILDS EWD INTO THE ERN LAKES RGN. FM SAT NGT THROUGH SUN...S/W MOVG INTO THE LWR MS VALLEY...AND IN COMBINATION W/ STALLED FNTL BNDRY ACRSS THE CAROLINAS...THERE WILL BE INCRSD COVERAGE OF CLDNS AND RAINFALL (FM THE SRN MTNS THROUGH THE TN VLY AND LWR MS VLY. BY SUN AFTN/EVE...CLDNS AND PCPN MAY BRUSH FAR SSW AREAS OF FA...OTRW SFC HI PRES RMNS OVR THE RGN...PROVIDING DRY/NR SEASONABLE CONDS. HI PRES TO BECOME SITUATED OFF THE E CST SUN NGT THROUGH MON...W/ TROUGH ALOFT DIGGING THROUGH THE MIDWEST. AT THE SAME TIME...S/W WILL BE MOVG E THROUGH THE LWR MS VLY/SE STATES. MDLS GENLY AGREE W/ INCRSG LLVL/MOIST FLO INTO THE MDATLC STATES...ESP ON MON...BRINGING A MDT/HI PROB FOR RAINFALL. HI CHCS FOR MON TO BE CONFINED TO INTR SECTIONS OF FA. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... MEDIUM RANGE PERIOD BEGINS WITH SOUTHERN STREAM SHORTWAVE TROUGH LIFTING NORTHEAST OUT OF THE DEEP SOUTH TOWARDS THE REGION... JUST AHEAD OF THE NRN STREAM TROUGH POISED TO MOVE ACROSS THE MOUNTAINS THROUGH TUESDAY. THE MODELS CONTINUE TO HANDLE THE UPPER TROUGH SIMILARLY, WITH LLVL S WINDS STREAMING MOISTURE-RICH GULF MOISTURE INTO THE REGION MONDAY NIGHT AND TUESDAY. PROGGED PW AND OMEGA FIELDS INDICATE THAT OVERRUNNING MOISTURE SHOULD BE STRONG ENOUGH TO WARRANT 50-60 POP FOR MONDAY NIGHT AND TUESDAY. FRONT APPROACHES THE REGION TUESDAY NIGHT, WITH THE FRONT LKLY TO CLEAR THE REGION WEDNESDAY. LOW/MIDLVL FLOW BECOMES W/NW WITH RESULTANT DOWNSLOPE FLOW SUFFICIENT TO BRING A DRY FORECAST FOR THE LATTER HALF OF THE WEEK AHEAD. FOR TEMPERATURES...EXPECT MAXIMA TO AVERAGE NEAR TO JUST BELOW CLIMO NORMAL FOR THE PERIOD. HIGHS GENERALLY INTO THE 70S TO NR 80. LOWS IN THE 60S TO NR 70 TUESDAY MORNING...FALLING BACK INTO THE 50S AND 60S TOWARDS THE MIDDLE OF NEXT WEEK, WITH SOME EARLY MORNING LOWS IN THE UPPER 40S POSSIBLE TOWARDS LATE NEXT WEEK WEST OF RIC. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... SCT-BKN CU (4-5K FT) NEXT SEVERAL HOURS SHUD DISSIPATE B4 SUNSET. WEAKENING FRONTAL BOUNDARY CROSSES FA LATE TONIGHT WITH ONLY SCT- BKN MID / HIGH LEVEL CLOUDS EXPECTED. DATA SUGGESTS A FEW HOUR PRD OF IFR CONDITIONS IN FOG AT KSBY PRIOR TO FROPA. WND SHIFT INTO THE NORTH BEHIND FROPA SAT MORNING WITH CLRG SKIES. NEXT CHC FOR PRECIP / LWR CIGS / VSBYS WILL BE MON INTO TUE NGT. && .MARINE... WEAK SFC RIDGING OVER THE NORTHEAST CONTINUES TO SAG INTO THE REGION THIS AFTERNOON...PROVIDING ONSHORE (E-NE) FLOW ~10 KT, WHICH WILL CONTINUE THROUGH TONIGHT. SEAS RUNNING 2-4FT NEAR SHORE (1-2FT BAY/SND). A WEAK (DRY) COLD FRONT WILL PUSH ACRS THE AREA LATE TONIGHT INTO SAT MORN. BRIEF PERIOD OF SCA EXPECTED OVER THE CHES BAY SAT MORNING INTO THE AFTN AND SCA HAS BEEN HOISTED FOR SATURDAY OVER THE CHES BAY AND RIVERS. WINDS DIMINISH WITH SLACKENING GRADIENT SAT AFTN AND EVENING. HOWEVER, SEAS OVER WATERS LOOK TO REMAIN IN 3-4 FT RANGE DUE TO INCOMING E-SE SWELL (15-20 SEC) ARRIVING ALONG THE MID-ATLANTIC COAST BEGINNING SAT EVENING THROUGH SUNDAY FROM DISTANT TROP STORM NADINE, WHICH IS ORIENTED WELL E/SE OF BERMUDA. THESE SWELLS WILL ALSO LIKELY RESULT IN CONTINUED ELEVATED RIP THREAT THROUGH THE WEEKEND. N-NW WINDS CONTINUE TO DIMINISH SAT NIGHT/SUN AS SFC HIGH PRESSURE SLIDES OVERHEAD. SFC RIDGE IS EXPECTED TO SLIDE OFF THE COAST LATER SUN THRU MON. A WARM FRONT THEN LIFTS ACROSS THE AREA DURING MON/MON NGT, WITH S-SE FLOW 15 KT OR LESS MON-TUE. TIGHTENING PRESSURE GRADIENT WILL ALLOW FOR INCREASING S/SE FLOW BY THE MIDDLE OF NEXT WEEK, WITH SCA LIKELY TO BE NEEDED IN ASSOCIATION W/NEXT FRONTAL PASSAGE TUE/WED OF NEXT WEEK. && .EQUIPMENT... AT SBY...NORMAL ASOS COMMS REMAIN DOWN AND ARE EXPECTED TO STAY DOWN FOR SEVERAL DAYS. OBS ARE BEING SENT BY THE TOWER BUT THESE UPDATES MAY NOT BE RELIABLE SO AMD NOT SKED WILL CONTINUE TO APPEAR IN THE TAFS. COMMS WITH ORF ASOS HAVE BEEN RESTORED. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SATURDAY FOR ANZ630>632-634>638. && $$ SYNOPSIS...ALB/SAM NEAR TERM...ALB SHORT TERM...ALB LONG TERM...MAM AVIATION...MPR MARINE...MAM EQUIPMENT...AKQ
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
739 PM EDT SAT SEP 15 2012 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 339 PM EDT SAT SEP 15 2012 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A WNW FLOW ALF OVER THE UPR GRT LKS TO THE W OF SLOWLY DEPARTING TROF IN QUEBEC AND E OF MORE ZONAL FLOW OVER THE NRN ROCKIES. SFC HI PRES UNDER THE CONFLUENT UPR FLOW IN THE GRT LKS IS CENTERED OVER SE ONTARIO JUST E OF THE SAULT. SOME SC LINGERS OVER THE ERN CWA EARLY THIS AFTN IN ASSOCIATION WITH DEPARTING H85 THERMAL TROF/LINGERING LLVL MSTR SHOWN ON THE 12Z APX RAOB. BUT AS THE HI IS SHIFTING TO THE E...THE SSW RETURN FLOW ON ITS WESTERN FLANK IS DRAWING WARMER/DRIER AIR NOTED TO THE W BACK INTO THE UPR LKS. 12Z H85 TEMPS ARE AS HI AS 20C AT BISMARCK. 12Z H85-7 DEWPT DEPRESSIONS ARE 20 TO 25C IN THE NRN PLAINS...WHERE PWAT IS GENERALLY 0.25 TO 0.50 INCH...AS LITTLE AS 50 PCT OF NORMAL. MOISTER AIR AT H925-85 LURKS TO THE S IN KANSAS/ MISSOURI. TONIGHT...AS THE HI TO THE E DRIFTS FARTHER AWAY UNDER WNW FLOW ALF...THE LLVL WIND IS FCST TO SHIFT TO THE WSW IN ADVANCE OF LO PRES TROF APRCHG FM THE W AHEAD OF SHRTWV EMBEDDED IN THE ZONAL FLOW ALONG THE NDAKOTA/CNDN BORDER THIS MRNG. THIS FLOW IS PROGGED TO ADVECT THE MUCH WARMER H85 AIR TO THE W THIS MRNG INTO THE UPR LKS...WITH H85 TEMPS FCST TO RISE AS HI AS 16-18C AT IWD BY 12Z SUN. ANY LINGERING LO CLDS OVER THE E SHOULD DISSIPATE EARLY WITH THE ARRIVAL OF THIS WARMER AND DRIER AIR. ALTHOUGH THE AIRMASS IS PROGGED TO REMAIN DRY THRU THE NGT...INCRSG H925 WINDS UP TO 30-35KTS LATE AS WELL AS THE ARRIVAL OF SOME PATCHY HI CLDS INDICATE TNGT WL BE MUCH WARMER THAN THIS MRNG. EXPECT THE HIEST MIN TEMPS OVER THE W AND NCNTRL NEAR LK SUP. SUN...INCOMING LO PRES TROF IS PROGGED TO DRIFT INTO THE WRN CWA IN THE AFTN AND INTERACT WITH H85 THERMAL RDG/AXIS OF H85 TEMPS IN THE 14-15C RANGE IN PLACE. ALTHOUGH MODELS INDICATE SW FLOW IN ADVANCE OF THE TROF WL ADVECT MOISTER LLVL AIR IN KS/MO THIS MRNG INTO THE UPR LKS...VERY DRY H85-7 AIR IN THE NRN PLAINS/ADJOINING SRN CAN AND LACK OF SGNFT DYNAMIC FORCING TO ERODE MID LVL CAPPING/CAUSE H5 FALLS WL BE LIMITING FACTORS FOR PCPN. EVEN WITH THESE NEGATIVES... SOME MODELS...ESPECIALLY THE CONSISTENT 12Z GFS...DO GENERATE SOME PCPN OVER MAINLY THE NRN TIER COUNTIES ALONG AND AHEAD OF THE INCOMING TROF. CONSIDERING THE NEGATIVES...OPTED TO FOLLOW THE DRIER 12Z NAM/LOCAL WRF-ARW MODELS AND MAINTAIN A PCPN-FREE FCST FOR MOST OF THE CWA. DID RETAIN GOING SCHC POPS OVER WRN AND NCNTRL LK SUP CLOSER TO MORE SUBSTANTIAL H5 FALLS ASSOCIATED WITH DEEPENING TROF IN SCNTRL CAN. FCST STEEP H7-5 LAPSE RATES IN EXCESS OF 7C/KM WARRANTS A MENTION OF TS IN THIS AREA DESPITE LIMITED MSTR. MIXING TO H8 ON NAM/GFS FCST SDNGS YIELDS HI TEMPS NEAR 80 OVER THE INTERIOR SCNTRL AWAY FM MODERATION OFF LK MI. WITH MORE MID/HI CLDS AND/OR THE ARRIVAL OF THE TROF/WSHFT TO THE W...TEMPS OVER THE W AND NRN TIER WL BE LOWER. THE COMBINATION OF THE UNSEASONABLE WARMTH OVER MAINLY THE SCNTRL...GUSTY WSW WINDS TO 25-30 MPH ENHANCED BY THE DEEPER MIXING...AND MIN RH DIPPING TO ARND 30 PCT AS DEWPTS MIX OUT INTO THE 45-50 RANGE DESPITE SLOW ARRIVAL OF MORE LLVL MSTR LATER IN THE DAY WL LEAD TO AN ELEVATED RISK OF WILDFIRES... ESPECIALLY OVER THE CNTRL AND E WHERE THE PRES GRADIENT WL REMAIN SHARPEST THRU THE DAY. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 339 PM EDT SAT SEP 15 2012 THE MAIN FORECAST CONCERN FOR SUNDAY NIGHT AND MONDAY ARE POPS ASSOCIATED WITH THE UPPER TROUGH AND COLD FRONT MOVING INTO THE UPPER LAKES. SUNDAY NIGHT SHOULD START OUT QUIET DESPITE THE COLD FRONT BEING OVER WESTERN LAKE SUPERIOR. MOISTURE IS VERY LIMITED ALONG THE FRONT SUNDAY EVENING...AND DYNAMICS ARE LACKING DUE TO THE UPPER JET STILL BEING WELL WEST OVER THE UPPER MIDWEST. HOWEVER...THIS IS EXPECTED TO CHANGE LATER SUNDAY NIGHT INTO MONDAY AS THE UPPER TROUGH SHARPENS AS A RESULT OF THE 110 KT UPPER JET DIVING SOUTH FROM THE YUKON SUNDAY NIGHT. THIS WILL ALLOW THE UPSTREAM THERMAL GRADIENT TO TIGHTEN AND ASSOCIATED FRONTOGENETIC CIRCULATION TO STRENGTHEN LATE SUNDAY AND INTO MONDAY AS IT MOVES INTO UPPER MICHIGAN. MEANWHILE...DEEPER PACIFIC ORIGIN MOISTURE WILL MOVE ACROSS THE REGION /WITH PRECIPITABLE WATER VALUES GREATER THAN 1 INCH/ AS SURFACE LOW PRESSURE DEVELOPS ALONG THE FRONT IN RESPONSE TO THE RIGHT ENTRANCE REGION OF THE JET MOVING OVERHEAD. THERE ARE SOME DIFFERENCES BETWEEN THE GFS AND NAM WITH REGARDS TO THE PLACEMENT OF THE LOW AND THE MOVEMENT OF THE COLD FRONT...WITH THE GFS BEING SLOWER AND AS SUCH FURTHER WEST WITH THE LOW PRES DEVELOPMENT COMPARED TO THE NAM. THE NAM TENDS TO AGREE MORE WITH THE 00Z ECMWF AND ALSO HAS SOME SUPPORT FROM SREF MEMBERS. INCREASING 850MB COLD ADVECTION WILL ALLOW FOR INCREASING LAKE INDUCED INSTABILITY LATE MONDAY INTO MONDAY NIGHT ON N-NW PBL WINDS ON THE NW SIDE OF THE LOW. ALL OF THIS SHOULD COMBINE TO GIVE A PERIOD OF STEADY RAIN STARTING LATE SUNDAY NIGHT AND CONTINUING THROUGH MONDAY...AND IN FACT CONTINUING INTO MONDAY NIGHT INTO TUESDAY FOR AREAS NEAR LAKE SUPERIOR. WITH THE LAKE AND TERRAIN ENHANCEMENT DUE TO NORTHERLY FLOW OFF THE LAKE...SOME AREAS CLOSE TO LAKE SUPERIOR COULD SEE 1-1.5 INCHES OF RAIN LATE SUNDAY NIGHT-TUESDAY MORNING. AS SUCH...HAVE OPTED TO MAKE ONLY MINOR TWEAKS TO THE GOING FORECAST FOR SUNDAY NIGHT INTO TUESDAY. DUE TO THE EXTREMELY DRY AIRMASS ALONG AND AHEAD OF THE FRONT...HAVE OPTED TO BACK OFF POPS ESPECIALLY SUNDAY EVENING. ALTHOUGH IT MAY TAKE A LITTLE TIME FOR THE FAR EAST TO SEE STEADY RAIN ON MONDAY DUE TO THE LOW PRESSURE DEVELOPMENT ALONG THE FRONT KEEPING THAT AREA IN THE WARM SECTOR A LITTLE LONGER...THE EXPECTATION IS THAT THE ENTIRE AREA WILL EVENTUALLY SEE RAIN MONDAY. WILL THEREFORE GO WITH CATEGORICAL POPS FOR THE ENTIRE FORECAST AREA ON MONDAY BUT WILL GO WITH THE HIGHEST POPS ACROSS NORTH CENTRAL AND WESTERN UPPER MICHIGAN DUE TO THE EVENTUAL LAKE/TERRAIN ENHANCEMENT DURING THE AFTERNOON. WILL CONTINUE WITH CATEGORICAL POPS NEAR LAKE SUPERIOR ON MONDAY NIGHT WITH NORTHERLY FLOW AND 850MB TEMPS DROPPING TO -3C...ALLOWING FOR LAKE INDUCED EQUILIBRIUM LEVELS ABOVE 20KFT. WOULD NOT BE SHOCKED IF THERE ARE SOME LIGHTNING STRIKES MONDAY NIGHT ESPECIALLY WITH THE UPPER TROUGH OVERHEAD. ALTHOUGH N-NW FLOW CONTINUES INTO TUESDAY...THE PBL FLOW BECOMES NEUTRAL OR EVEN ANTI-CYCLONIC AS THE DAY GOES ON. IN ADDITION...THE DEEP MOISTURE SHOULD BE SCOURED OUT AND THE BEST Q-VECT CONVERGENCE MOVES EAST. DUE TO THE MODERATE LAKE INSTABILITY FROM 850MB TEMPS AROUND -3C COMBINED WITH ONSHORE FLOW...CANNOT REMOVE POPS NEAR THE LAKE...BUT WILL CONTINUE WITH SCATTERED POPS. BY TUESDAY EVENING...IT SHOULD START TO CLEAR OUT AS THE UPR TROUGH MOVES EAST AND THE SFC HIGH MOVES OVERHEAD. ALTHOUGH THE 12Z GFS IS QUITE PROGRESSIVE IN MOVING THE HIGH TO THE EAST TUE NIGHT...THE GEM AND ECMWF ARE CONSISTENT IN SHOWING A SLOWER AND LESS PROGRESSIVE SOLN. WITH THE HIGH BEING OVERHEAD...IT LOOKS LIKE A GOOD RADIATIONAL COOLING NIGHT ESPECIALLY ACROSS THE INTERIOR WEST AWAY FROM ANY REMAINING LAKE CLOUDS...SO AREAS OF FROST ARE EXPECTED...IF NOT A HARD FREEZE. TEMPS FOR MONDAY/TUESDAY WILL REMAIN BELOW NORMAL...ALTHOUGH MONDAY WILL BE WARMER THAN TUESDAY...ESPECIALLY ACROSS THE EAST. WITH 850MB TEMPS AROUND -3C ON TUESDAY AND BLUSTERY N-NW FLOW...EXPECT TEMPS TO STRUGGLE TO REACH 50...ESPECIALLY WHERE IT STAYS CLOUDY FOR MUCH OF THE DAY NEAR LAKE SUPERIOR. IN THE EXTENDED /WED-NEXT SATURDAY/...IT CERTAINLY LOOKS LIKE A AUTUMN PATTERN ACROSS THE GREAT LAKES AS THE PATTERN WILL BE DOMINATED BY AN INTENSIFYING LONGITUDINAL TROUGH ACROSS CENTRAL CANADA AND EXTENDING SOUTHWARD INTO THE GREAT LAKES REGION BY THE END OF THE WEEK. THIS WILL ALLOW FOR THE UNSETTLED AND COOL WEATHER TO CONTINUE. AS FOR THE SPECIFICS...THE FIRST UPPER LOW THAT WILL PLAGUE THE AREA EARLY IN THE WEEK WILL EJECT OUT TUE NIGHT/WED IN RESPONSE TO ANOTHER SHORTWAVE DIVING DOWN THE BACK SIDE OF THE LONG WAVE TROUGH. THIS SHOULD ALLOW FOR BRIEF RIDGING TO BUILD ACROSS THE UPPER GREAT LAKES WED BEFORE THE NEXT SYSTEM MOVES IN AND CLOSES OFF OVER THE GREAT LAKES BY FRI. AS SUCH...WILL CONTINUE WITH CHANCE POPS FOR THE ENTIRE AREA THURSDAY. AS THE EVENT BECOMES A LITTLE CLEARER IN THE NEXT FEW DAYS...POPS WILL LIKELY NEED TO BE INCREASED IN THE FRIDAY/SATURDAY TIME PERIOD AS IT WILL BE COLD ENOUGH ALOFT FOR LAKE ENHANCEMENT AND MOST OF THE NAEFS MEMBERS ALL HAVE RAIN ON FRIDAY INTO SATURDAY. THE UPPER LOW SETTLES OVER THE GREAT LAKES ON SATURDAY...ALTHOUGH THE ECMWF POSITION IS SOUTH OF THE GFS POSITION. REGARDLESS...SATURDAY LOOKS UNSETTLED AND RATHER WET. TEMPS THROUGH THE EXTENDED PERIOD WILL BE BELOW NORMAL. FRIDAY AND ESPECIALLY SATURDAY COULD STRUGGLE TO GET OUT OF THE UPPER 40S IF IT STAYS CLOUDY AND RAINY FOR THE ENTIRE DAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 737 PM EDT SAT SEP 15 2012 VFR CONDITIONS WILL CONTINUE AT KIWD/KCMX/KSAW THRU THIS FCST PERIOD AS LOW-LEVELS REMAIN DRY DESPITE HIGH PRES RETREATING AND A COLD FRONT APPROACHING. TIGHTENING PRES GRADIENT BTWN THE HIGH PRES TO THE E AND APPROACHING COLD FRONT ACROSS THE NRN PLAINS WILL LEAD TO LLWS TONIGHT. OTHER THAN WIND SHIFT...COLD FRONT WILL PASS KIWD/KCMX UNEVENTFULLY SUN AFTN. IT WILL BE BEYOND THIS FCST PERIOD THAT RAIN CHANCES WILL INCREASE AS DYNAMICS STRENGTHEN WITH TROF DEEPENING INTO THE UPPER MISSISSIPPI VALLEY. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 339 PM EDT SAT SEP 15 2012 EXPECT ESE WINDS UP TO 20 KTS THIS AFTERNOON TO VEER TO THE WSW TONIGHT INTO SUN AS HI PRES IN SE ONTARIO RETREATS TO THE E AND A LO PRES TROF APPROACHES FROM THE NW. LOW PRESSURE WILL DEVELOP ALONG A COLD FRONT MOVING ACROSS THE UPPER LAKES ON MONDAY. IT WILL DEEPEN AT IT MOVES JUST EAST OF LAKE SUPERIOR ON MONDAY. THE TIGHTENING PRESSURE GRADIENT COMBINED WITH INCREASING LAKE INSTABILITY WILL ALLOW FOR GALE FORCE NORTHERLY WINDS ACROSS CENTRAL LAKE SUPERIOR MONDAY AND THEN ACROSS THE EAST HALF OF LAKE SUPERIOR MONDAY NIGHT. HIGH PRESSURE BUILDS IN TUESDAY NIGHT BEFORE A BROAD AREA OF LOW PRESSURE MOVES SOUTH THU AND FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... GALE WATCH FROM MONDAY EVENING THROUGH TUESDAY MORNING FOR LSZ267. GALE WATCH FROM MONDAY EVENING THROUGH LATE MONDAY NIGHT FOR LSZ266. GALE WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING FOR LSZ264. GALE WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING FOR LSZ263. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...MRD AVIATION...ROLFSON MARINE...KC/MRD
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
122 AM EDT FRI SEP 14 2012 .SYNOPSIS... ISSUED AT 427 PM EDT THU SEP 13 2012 A COLD FRONT WILL BRING RAIN TO THE AREA OVERNIGHT. THIS WILL BE FOLLOWED BY COOLER BUT STILL SEASONABLE TEMPERATURES AROUND 70 ON FRIDAY. AFTER A GRADUAL WARMING TREND TO THE MID 70S THROUGH MONDAY...ANOTHER COLD FRONT WILL BRING A CHANCE FOR RAIN SHOWERS MONDAY NIGHT AND TUESDAY ALONG WITH HIGH TEMPERATURES IN THE 60S. && .UPDATE... ISSUED AT 121 AM EDT FRI SEP 14 2012 UPDATE TO CANCEL THE REMAINDER OF THE SCA. UPDATE ISSUED AT 1025 PM EDT THU SEP 13 2012 UPDATE TO EXPIRE SCA NORTH OF GRAND HAVEN. ALSO TWEAKED POPS SLIGHTLY. UPDATE ISSUED AT 424 PM EDT THU SEP 13 2012 FORECAST WAS UPDATED TO ACCOUNT FOR THE SHOWERS DEVELOPING FROM LANSING TO NEAR KALAMAZOO. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 335 PM EDT THU SEP 13 2012 TREND ON THE RAIN FOR TONIGHT HAS BEEN DOWN IN TERMS OF AMOUNTS FOR SEVERAL MODEL RUNS NOW. REGIONAL RADAR LOOPS DO NOT LOOK OVERLY IMPRESSIVE EITHER. STILL...EXPECT A BAND OF RAIN TO WORK THROUGH THE ENTIRE FORECAST AREA BRINGING AMOUNTS ON THE ORDER OF A TENTH OR TWO AT MOST LOCATIONS. THE FAR SOUTHEAST TOWARD JACKSON MAY SEE SLIGHTLY HIGHER AMOUNTS. PRECIPITATION IS BEING FOCUSED BY THE RIGHT ENTRANCE REGION OF A 300MB JET. CURRENT THINKING BASED ON SPC AND NSSL WRF MODEL RUNS AND THE TRENDS IN THE LATEST HRRR IS THAT THE RAIN WILL BE OFF TO THE EAST OF THE FORECAST AREA BY 12Z ON FRIDAY. LOOKING FOR SOME MORNING CUMULUS DEVELOPMENT ON FRIDAY WITH DRIER AIR TAKING OVER DURING THE AFTERNOON. IN GENERAL EXPECTING A PARTLY CLOUDY TO MOSTLY SUNNY FORECAST FOR FRIDAY. FEEL THE AIR MASS WILL BE TOO DRY FOR ANY SHOWER DEVELOPMENT OFF THE LAKE DESPITE DELTA T/S IN THE MIDDLE TEENS C. FRIDAY NIGHT THROUGH SATURDAY NIGHT LOOKS QUIET AND DRY WITH HIGH PRESSURE IN CONTROL. .LONG TERM...(SUNDAY THROUGH THURSDAY) ISSUED AT 335 PM EDT THU SEP 13 2012 FAIR WX WITH SEASONABLY MILD TEMPS IS ANTICIPATED SUNDAY THROUGH MONDAY AFTERNOON IN A SOUTHERLY FLOW WAA PATTERN IN ADVANCE OF THE APPROACHING COLD FRONT. THAT FRONT WILL BRING SOME SHOWERS MONDAY NIGHT THROUGH TUESDAY. LAKE EFFECT CLOUDS AND SHOWERS ARE ANTICIPATED TUESDAY NIGHT INTO WEDNESDAY AS H8 TEMPS (BRIEFLY) DIP DOWN TO AROUND 0 TO -1 C BEFORE MODERATING. IT WILL TURN COOLER TUESDAY THROUGH MIDWEEK AS A FAIRLY DEEP LONGWAVE UPPER LEVEL TROUGH DEVELOPS FROM THE UPPER MIDWEST TO GREAT LAKES REGIONS. A SECONDARY COLD FRONT WILL BRING THE CHANCE FOR ADDITIONAL SHOWERS WEDNESDAY NIGHT THROUGH THURSDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1153 PM EDT THU SEP 13 2012 LOW LEVEL MOISTURE ASSOCIATED WITH THE BAND OF RAIN MOVING THROUGH HAS CREATED SOME IFR ROUGHLY KLAN TO KAZO...EAST. WITH THE BAND OF RAIN ADVANCING EAST...THERE STILL COULD BE SOME IFR THROUGH ABOUT 09Z. CLEARING BEHIND THE RAIN BAND...MAY ALLOW FOR GROUND FOG TO FORM...BUT DRIER AIR WAS WORKING IN...SO NOT CONFIDENT ON THIS AT THIS TIME. WILL MONITOR TRENDS IN THE NEXT FEW HRS. MIXING ON FRI WILL ALLOW FOR SOME GUSTY WINDS...ESPECIALLY KGRR TO KMKG && .MARINE... ISSUED AT 335 PM EDT THU SEP 13 2012 HAVE OPTED TO KEEP THE CURRENT CONFIGURATION TO THE SMALL CRAFT ADVISORIES WITH THE NORTH ENDING THIS EVENING AND THE SOUTH OVERNIGHT. GRADIENT TURNS LAX TONIGHT IN THE WAKE OF FIRST FRONTAL PASSAGE WHICH LEADS TO A DECAYING WAVE FIELD. WINDS INCREASE AGAIN ON FRIDAY THOUGH IN THE WAKE OF A SECONDARY FRONT LATE TONIGHT. WINDS WILL LIKELY NOSE UP TOWARDS 20 KNOTS FRIDAY WHICH SHOULD BUILD A SOLID 3-5 FOOT WAVE FIELD DURING THE DAY. SO...RATHER THAN STRETCH THE CURRENT SCA THROUGH TOMORROW THROUGH A 8-12 PERIOD OF QUIET WAVES LATE TONIGHT AND TOMORROW MORNING OPTED TO LET THE CURRENT HEADLINES EXPIRE TONIGHT. A NEW SCA WILL LIKELY BE NEED FOR FRIDAY WITH THE OVERNIGHT FORECAST PACKAGE IF THE CURRENT FORECAST WINDS HOLD. && .HYDROLOGY... ISSUED AT 335 PM EDT THU SEP 13 2012 NO HYDRO ISSUES ANTICIPATED WITH RAINFALL AMOUNTS PROBABLY ENDING UP BELOW A THIRD OF AN INCH IN MANY AREAS TONIGHT. HIGHEST AMOUNTS WILL BE IN THE FAR SOUTHEAST REACHES OF THE FORECAST AREA TOWARDS JACKSON. RIVER LEVELS ARE LOW AND WELL WITHIN BANK. THE NEXT CHANCE FOR RAIN DOES NOT COME UNTIL EARLY NEXT WEEK AFTER TONIGHT. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ UPDATE...JK SYNOPSIS...TJT SHORT TERM...DUKE LONG TERM...LAURENS AVIATION...MJS HYDROLOGY...DUKE MARINE...DUKE
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1148 PM CDT THU SEP 13 2012 .UPDATE... ISSUED AT 901 PM CDT THU SEP 13 2012 WATCHING RADAR RETURNS DRY UP OVER CENTRAL AND WESTERN MISSOURI ATTM. AM UNSURE YET HOW THIS WILL ALL UNFOLD DURING THE OVERNIGHT HOURS THOUGH...RAP AND HRRR ARE SHOWING THAT THE PRECIP CURRENTLY OVER EASTERN KANSAS WILL SPREAD EASTWARD OVER THE NEXT FEW HOURS TO FILL IN BEHIND THE DRYING IN CENTRAL MO...AND CURRENT RADAR TRENDS OVER EASTER KANSAS ARE STARTING TO SUPPORT THIS IDEA. ADDITIONALLY...THE BRAND SPANKING NEW 14/00Z NAM IS ROLLING IN AND IS INDICATING MORE OR LESS THE SAME THING. WILL GO AHEAD AND BUMP UP POPS AFTER MIDNIGHT ALONG AND SOUTH OF THE I-70 CORRIDOR...AND LINGER PRECIP INTO FRIDAY MORNING FROM THE STL METRO AREA SOUTH AND EAST. ISSUED AT 604 PM CDT THU SEP 13 2012 AM RECONFIGURING POPS FOR TONIGHT...INCREASING TO CATEGORICAL IN THE NORTHEAST MO/WEST CENTRAL IL FOR THE FIRST FEW HOURS OF THE FORECAST BASED ON RADAR TRENDS...AND DROPPING LIKELY POPS ACROSS MUCH OF THE REST OF THE AREA THIS EVENING. ALL MODELS SHOW SOME DECENT ISENTROPIC LIFT AS THE LOW LEVEL BAROCLINIC ZONE SLIPS SOUTHEAST BEHIND THE FRONT SO WILL MARCH LIKELY POPS SLOWLY SOUTHEAST THROUGH THE EVENING HOURS. 18Z NAM DROPS SOME PRETTY DECENT 925-850MB FRONTOGENESIS DOWN THROUGH EASTERN MISSOURI AND SOUTHWEST ILLINOIS OVERNIGHT BETWEEN 09Z AND 12Z FRIDAY MORNING SO WILL CONTINUE TO MARCH THE LIKELIES SOUTHEAST THROUGH THE OVERNIGHT HOURS. CARNEY && .SHORT TERM... ISSUED AT 308 PM CDT THU SEP 13 2012 (TONIGHT) THE PRIMARY FCST ISSUES FOR TONIGHT ARE TEMPERATURE AND PCPN TRENDS. A CDFNT WAS MOVING THROUGH MISSOURI AND ILLINOIS THIS AFTN WITH EXTENSIVE CLOUDINESS AND SCT SHRA LOCATED BEHIND IT. A MARKED TEMPERATURE CONTRAST WAS NOTED ACROSS THE FRONT AT 19Z WITH LOW TO MID 80S IN THE MOSTLY CLEAR AREAS AHEAD OF THE BDRY AND LOW 50S TO LOW 60S BENEATH THE POST-FRONTAL CLOUD SHIELD. THE KEY FEATURE GOVERNING OVERNIGHT LOWS WILL BE THE DURATION /AND HEIGHT/ OF CLOUD COVER. LOW-MID CLOUDS THAT PERSIST FOR MOST OF THE NIGHT WOULD SUPPORT LESS OF A TEMPERATURE DROP THAN WOULD THINNER CIRRUS OR CLR SKIES. CONDENSATION PRESSURE DEFICIT PLOTS FOR VARIOUS LAYERS BETWEEN 850MB AND 500MB SUPPORT THE IDEA THAT ALL BUT THE FAR NWRN PART OF THE CWA WILL REMAIN CLOUDY OVERNIGHT THEREFORE KEPT THE COOLEST OVERNIGHT LOWS IN THE NWRN CWA. ASIDE FROM A STRAY SPRINKLE OR TWO...NEARLY ALL OF THE PCPN HAS BEEN POST-FRONTAL IN NATURE AND FREE OF LIGHTNING. ATTM IT LOOKS LIKE THE AREA OF POST-FRONTAL SHRA SHOULD SLOWLY SHIFT SEWD WITH TIME BASED ON MODEL DEPICTIONS OF H9/H85 FRONTOGENETICAL FORCING WITH LIMITED INSTABILITY. KANOFSKY && .LONG TERM... ISSUED AT 309 PM CDT THU SEP 13 2012 (FRIDAY THROUGH THURSDAY) WILL SEE SOME LINGERING LIGHT RAIN SHOWERS OVER SOUTHEAST MO AND SOUTHERN IL AS SYSTEM EXITS REGION ON FRIDAY MORNING. WITH COOLER AND DRIER AIR FILTERING IN TEMPS WILL STRUGGLE TO WARM UP MUCH. HIGHS WILL BE IN THE LOW TO MID 70S...WITH THE COOLEST TEMPS SOUTH DUE TO LINGERING CLOUD COVER IN THIS AREA. FOR THE WEEKEND...A TRICKY FORECAST AS MOST MODELS NOW TRYING TO DEVELOP SOME OVER RUNNING PCPN OVER SOUTHWESTERN MO ALONG OLD COLD FRONTAL BOUNDARY LATE SATURDAY THROUGH SUNDAY. FOR NOW CONFIDENCE IS LOW...SO JUST HAVE SLIGHT CHANCE POPS FOR FAR SOUTHWESTERN PORTIONS OF FORECAST AREA SATURDAY NIGHT AND SUNDAY. AS FOR TEMPS...LOWS FRIDAY NIGHT WILL BE IN THE UPPER 40S TO MID 50S. HIGHS THROUGH THE WEEKEND WILL BE IN THE MID TO UPPER 70S. BY LATE SUNDAY NIGHT...NEXT COLD FRONT BEGINS TO MOVE INTO MO. WILL SEE FRONT MOVE INTO FORECAST AREA MONDAY WITH SOME DECENT INSTABILITY AND MOISTURE...SO HAVE SHOWERS AND THUNDERSTORMS POSSIBLE THROUGH MONDAY EVENING...BEFORE PCPN TAPERS OFF TOWARDS DAYBREAK ON TUESDAY. HIGHS WILL BE IN THE MID TO UPPER 70S ON MONDAY...BEFORE DROPPING OFF INTO THE MID 60S FAR NORTH TO THE LOW 70S FAR SOUTH ON TUESDAY. COLDEST NIGHT WILL BE TUESDAY NIGHT WITH LOWS IN THE LOW TO MID 40S. BEYOND THAT EXTENDED MODELS BRING IN ANOTHER COLD FRONT WEDNESDAY NIGHT AND THURSDAY WITH ANOTHER CHANCE FOR SHOWERS. BYRD && .AVIATION... ISSUED AT 1135 PM CDT THU SEP 13 2012 CDFNT AT 04Z HAS CLEARED THE ENTIRE FA AND CONTINUES TO BE IDENTIFIED CLEARLY VIA FINE LINE ON RADAR MOSAIC. MVFR CIGS ARE EDGING INTO THE STL METRO AREA AT THIS TIME AND EXTEND BACK TO THE AXIS OF LIGHT RAIN NEAR KUIN-KCOU. POCKETS OF IFR CIGS CONTINUE TO EXIST AS WELL. NNE FLOW AT 1-2KFT WILL GRADUALLY VEER TO A MORE SOLID NE BY EARLY FRIDAY MORNING AND THIS SHOULD RESULT IN LO CIGS BECOMING MORE STAGNANT AROUND THE STL METRO AREA FOR A PERIOD FRIDAY MORNING...WHILE THIS MAIN AREA OF LO CLOUD SHOULD BE READY TO CLEAR OUT OF KCOU SOON AS IT HAS ALREADY DONE AT KUIN. STILL RATHER SOLID BAND OF LIGHT RAIN WELL BEHIND THE FRONT FROM CNTRL IL SWWD THRU MID-MISSOURI AND INTO SERN KS...WHILE THINNING AS EXPECTED ON ITS ERN FLANK...HAS BEEN RE-INVIGORATED BY UPSTREAM WAVE IN THE W...AND SHOULD KEEP THE -RA...AROUND CNTRL MO ESPECIALLY...A BIT LONGER. THIS RE-INVIGORATION SHOULD ALSO SERVE TO GIVE STL METRO A SPOT OF RAIN TOWARD DAYBREAK AS WELL. LO CIGS ARE THEN EXPECTED TO CLEAR OUT OF STL METRO BY LATE FRIDAY MORNING LEAVING BEHIND A STILL EXPANSIVE REGION OF HI CLOUDS. SPECIFICS FOR KSTL...N SFC WNDS TO GRADUALLY VEER NE FOR FRIDAY AND THEN E AND VERY LIGHT FOR FRIDAY NIGHT...EXPECTED ARRIVAL OF LO CLOUDS FROM THE N TOWARDS MIDNIGHT IS IMMINENT...WITH PERSISTENCE LIKELY THRU MID FRIDAY MORNING...HAVE ADDED IN A PERIOD OF IFR AROUND 12Z WITH IT MORE PROBABLE NOW BASED ON UPSTREAM OBS...A PERIOD OF LIGHT RAIN EXPECTED AROUND DAWN... IMPROVEMENT TO VFR THEN EXPECTED BY MIDDAY IF NOT SOONER. TES && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1128 AM EDT FRI SEP 14 2012 .SYNOPSIS... A COLD FRONT WILL CROSS THE REGION TODAY ALONG WITH SOME SHOWERS. FOLLOWING THE COLD FRONT...SEASONABLY COOLER AIR WILL OVERSPREAD THE AREA FOR THE UPCOMING WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... 15Z SURFACE ANALYSIS SHOWS SLOW-MOVING COLD FRONT ORIENTED FROM JUST WEST OF OTTAWA ONTARIO SOUTHWEST ACROSS CENTRAL LAKE ONTARIO TO JUST WEST OF NIAGARA FALLS AND BUFFALO AND SOUTHWEST ACROSS LAKE ERIE TO NEAR CLEVELAND. BOTH VISIBLE SATELLITE AND RADAR IMAGERY SHOW ASSOCIATED CLOUDS AND SHOWERS JUST WEST OF THE LEADING EDGE WHICH IS A CLASSIC ANAFRONTAL SIGNATURE. BROAD BAND OF SHOWERS...ABOUT 100 MILES WIDE...ARE APPROXIMATELY 80 MILES WEST OF BUFFALO. ALOFT THE SHOWERS ARE FORCED BY A MID-LEVEL TROUGH SHIFTING ACROSS THE GREAT LAKES AND A 65KT JET ROUNDING THE BASE OF THE TROUGH. AS OF 15Z NO LIGHTING HAS BEEN OBSERVED BUT AS THE SYSTEM MOVES CLOSER TO THE EASTERN LAKES SOME STRENGTHENING OF THIS JET ALONG WITH MODEL INDICATED INSTABILITY INCREASING AHEAD OF THE MAIN AREA OF SHOWERS COULD PRODUCE SOME ISOLATED LIGHTING. THIS IS ESPECIALLY TRUE IF ANYTHING CONVECTIVE FORMS AHEAD OF THE MAIN LINE LIKE RECENT HRRR RUNS HAVE HINTED AT. WILL SHIFT CONVECTIVE CHANCES EAST ALONG THE LEADING EDGE CLOSER TO THE INSTABILITY AND REMOVE FROM MAIN SHOWERS. TIMING OF THE SHOWERS SHOULD KEEP MUCH OF THE AREA DRY THROUGH THE EARLY AFTERNOON WITH SHOWERS ARRIVING 19-20Z ACROSS THE FAR WEST...20-21Z OR SO ACROSS THE GENESEE VALLEY...21-22Z ACROSS THE FINGER LAKES (OR EARLIER IF CONVECTION DEVELOPS)...AND 22Z/23Z ACROSS THE NORTH COUNTRY. AT THIS POINT...ALL INDICATIONS POINT TO THE STEADIEST PRECIP LASTING FOR ROUGHLY A 3-4 HOUR WINDOW...BEFORE QUICKLY TAPERING OFF FROM WEST TO EAST BETWEEN LATE THIS AFTERNOON AND THIS EVENING. TONIGHT...THE ANAFRONTAL PRECIP WILL FINISH TAPERING OFF ACROSS OUR EASTERN ZONES THIS EVENING...WHILE A NORTHWESTERLY FLOW OF MUCH COOLER AIR OVERSPREADS THE AREA BEHIND THE DEPARTING FRONT...WITH 850 MB TEMPS FALLING TO +4C TO +6C BY LATE TONIGHT. WITH SOME LINGERING SYNOPTIC-SCALE MOISTURE STILL IN PLACE BEHIND THE FRONT...THIS SHOULD BE ENOUGH TO EVENTUALLY TRIGGER A LIMITED LAKE RESPONSE SOUTHEAST OF LAKE ONTARIO...WHERE SOME SCATTERED LAKE EFFECT RAIN SHOWERS WILL DEVELOP DURING THE OVERNIGHT HOURS. IN TERMS OF TEMPERATURES...READINGS TODAY WILL EXHIBIT A WEST TO EAST GRADIENT GIVEN THE APPROACH AND PASSAGE OF THE FRONT...WHILE ALSO TENDING TO MAX OUT IMMEDIATELY PRIOR TO ITS PASSAGE AND THE ONSET OF THE MAIN BAND OF SHOWERS...AFTER WHICH TIME TEMPS SHOULD STEADILY COOL. EXPECT HIGHS TO RANGE FROM THE LOWER TO MID 70S ACROSS THE FAR WEST...TO THE LOWER 80S ACROSS EASTERN SECTIONS WHERE THE FRONT WILL ARRIVE LAST AND WHERE THERE WILL MORE IN THE WAY OF SUNSHINE TO HELP MIX DOWN THE +13/+14C TEMPS AT 850 MB. AFTER THAT...MUCH COOLER AIR WILL OVERSPREAD THE REGION AND RESULT IN OVERNIGHT LOWS RETURNING TO MUCH MORE SEASONABLE LEVELS IN THE UPPER 40S AND LOWER 50S TONIGHT. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... A LOW AMPLITUDE FLOW OVER THE NORTH ATLANTIC WILL KEEP A PROGRESSIVE PATTERN IN PLACE ACROSS OUR REGION THROUGH MUCH OF NEXT WEEK...AND FOR THIS PARTICULAR PERIOD...THAT WILL INCLUDE AN EXPANSIVE SFC HIGH THAT WILL KEEP THE WEEKEND LARGELY DRY AND COMFORTABLE. WHILE WE WILL START OFF SEASONABLY COOL...TEMPERATURES HEADING INTO EARLY NEXT WEEK WILL TREND HIGHER. THE DETAILS... THIS PERIOD WILL OPEN WITH SOME NUISANCE LAKE EFFECT RAIN SHOWERS SOUTHEAST OF LAKE ONTARIO AS A CHILLY NORTHWEST FLOW OF 4C H85 AIR WILL BE FOUND OVER THE LOWER LAKES. AT THIS POINT YESTERDAY... GUIDANCE WAS SUGGESTING THAT THE AIRMASS MIGHT BE TOO DRY FOR MUCH LAKE RESPONSE. THAT HAS SINCE CHANGED WITH BOTH THE NAM AND RGEM LEANING TOWARDS A FAIRLY MOIST ENVIRONMENT BELOW 8K FT WHERE A WEAK INVERSION WILL BE IN PLACE. A WELL ALIGNED 300 FLOW MAY EVEN ALLOW FOR A CONNECTION TO GEORGIAN BAY...WHICH WOULD FAVOR A WELL DEFINED EARLY SEASON BAND FROM ABOUT WAYNE COUNTY SOUTHEASTWARD WITH MORE SCATTERED SHOWERS WITHIN 25 MILES EITHER SIDE OF THE AXIS. IF THE MULTI-LAKE CONNECTION DOES DEVELOP...ANY SINGLE BAND WOULD QUICKLY BREAK DOWN AND BECOME MULTI-CELLULAR BY MID MORNING. AS SATURDAY WEARS ON...LARGE SCALE SUBSIDENCE ASSOCIATED WITH AN APPROACHING SFC HIGH OVER LOWER MICHIGAN WILL COMBINE WITH STRONG DIURNAL MIXING TO BREAK DOWN/END THE LAKE DRIVEN ACTIVITY. THIS PROCESS WOULD ALSO PROMOTE SOME SUNSHINE ELSEWHERE ACROSS OUR FORECAST AREA WITH THE LAKE EFFECT RAIN SHOWERS ENDING BY MID AFTERNOON. AS ONE WOULD EXPECT WITH H85 TEMPS AROUND 4C...IT WILL BE COOL ON SATURDAY WITH HIGHS ONLY IN THE 60S. THE SFC HIGH WILL DRIFT ACROSS LAKE ERIE SATURDAY NIGHT...WITH MAINLY CLEAR SKIES AND LIGHT WINDS SUPPORTING VERY GOOD RADIATIONAL COOLING. OVERNIGHT LOWS WILL RANGE FROM THE MID AND UPPER 30S ACROSS THE NORTH COUNTRY AND SRN TIER VALLEYS TO THE MID 40S ALONG THE IMMEDIATE LAKE SHORES. WHILE THIS WILL ALSO MEAN A FAIR AMOUNT OF VALLEY FOG ACROSS THE SRN TIER...WE WILL ALSO HAVE THE LIKELIHOOD FOR THE FIRST FROST OF THE SEASON. IT IS STILL TOO EARLY TO ISSUE ANY FROST RELATED PRODUCTS BUT WATCH FOR POSSIBLE ADVISORIES AS THE EVENT DRAWS CLOSER. ON SUNDAY...THE DOMINANT HIGH PRESSURE SYSTEM WILL DRIFT SOUTHEAST TO THE MID ATLANTIC STATES WHILE OUR AIRMASS MODIFIES TO MORE COMFORTABLE LEVELS. AMPLE SUNSHINE COUPLED WITH H85 TEMPS ELEVATING TO 8C WILL FAVOR AFTERNOON HIGHS WITHIN A FEW DEGREES OF 70. ALL IN ALL...THIS SHOULD BE A BEAUTIFUL DAY FOR GETTING OUT AND ENJOYING THE OUTDOORS. OUR NEXT COLD FRONT WILL SLOWLY SETTLE ACROSS THE UPPER GREAT LAKES SUNDAY NIGHT WHILE OUR CONTROLLING SFC HIGH WILL MOVE OFF THE EAST COAST. THE STRENGTHENING SOUTHERLY FLOW BETWEEN THE SYSTEMS WILL HELP TO HOLD OUR TEMPERATURES AT LEAST 5 DEGREES F HIGHER THAN THE PREVIOUS CHILLY NIGHT...SO THAT SUNDAY NIGHT LOWS WILL RANGE FROM THE 40S EAST OF LK ONTARIO AND IN THE SRN TIER VALLEYS TO THE LOWER 50S MOST ELSEWHERE. THE AFOREMENTIONED COLD FRONT WILL ONLY MAKE IT AS FAR SOUTHEAST AS LOWER MICHIGAN ON MONDAY AS A SIGNIFICANT WAVE RIDING UP ALONG THE FRONT WILL IMPEDE ITS PROGRESS. THIS WILL BENEFIT OUR REGION IN THAT MONDAY WILL FEATURE CONTINUED WARMING WITH AFTERNOON TEMPERATURES TOPPING OUT IN THE MID TO UPPER 70S. IN TERMS OF SUNSHINE... SUNNY SKIES EARLY WILL PROBABLY FADE BEHIND INCREASING HIGH CLOUDINESS... BUT IT WILL STILL BE A NICE DAY BY ANYONES STANDARDS. MOISTURE BEING DRAWN NORTHWARDS AHEAD OF THE SLOW MOVING FRONT MONDAY NIGHT COULD LEAD TO SOME SHOWERS OVERNIGHT WITH TEMPERATURES BEING HELD WELL ABOVE NORMAL. && .LONG TERM /TUESDAY THROUGH THURSDAY/... A HIGH AMPLITUDE FLOW WILL BE IN PLACE ACROSS NORTH AMERICA DURING THIS PERIOD...WITH AN ANOMALOUSLY DEEP TROUGH BEING CENTERED OVER THE UPPER GREAT LAKES. THIS WILL INITIALLY RESULT IN SOME VERY UNSETTLED WEATHER ACROSS OUR REGION WHICH WILL THEN BE FOLLOWED BY SEASONABLY COOL CONDITIONS. BREAKING THIS DOWN ON A DAY BY DAY BASIS... A STRONG SHORTWAVE WILL DIVE INTO AN ALREADY DEEP LONGWAVE TROUGH OVER THE UPPER GREAT LAKES ON TUESDAY WHILE A 1000MB SFC LOW WILL LIFT ACROSS NEW YORK STATE. THIS WILL LIKELY PRODUCE A RAINY DAY ACROSS OUR REGION WITH MANY AREAS PICKING UP A HALF TO ONE INCH OF RAINFALL. FROM THIS DISTANT VANTAGE POINT...GUIDANCE IS SUGGESTING THAT A 120KT H25 JET OVER SRN ONTARIO WILL PRODUCE THE STRONGEST JET ENHANCED LIFT OVER THE FINGER LAKES AND EASTERN LAKE ONTARIO REGION SO THAT IS WHERE THE HEAVIER RAIN WILL BE MOST FAVORABLE. AS THE VIGOROUS SHORTWAVE ROUNDS THE BASE OF THE H5 TROUGH TUESDAY NIGHT...THE SFC LOW WILL LIFT AWAY ACROSS QUEBEC. THE ISENTROPIC LIFT WILL EXIT TO THE NORTHEAST IN THE PROCESS...BUT DEEP SYNOPTIC MOISTURE WILL WRAP BACK ACROSS OUR FORECAST AREA WHILE THE H5 TROUGH WILL BECOME NEGATIVELY TILTED AND LIFT OVER THE LOWER GREAT LAKES. THIS SHOULD KEEP AT LEAST SCATTERED SHOWERS OVER OUR REGION... ALTHOUGH STRONG COLD ADVECTION ON THE BACKSIDE OF THE SFC LOW WILL PROMOTE LAKE ENHANCEMENT TO THE ONGOING SYNOPTIC SHOWERS. ON WEDNESDAY...THE BASE OF THE H5 TROUGH WILL LIFT AWAY ACROSS QUEBEC WHILE A FLAT SHORTWAVE RIDGE WILL QUICKLY FOLLOW IN ITS WAKE. THE ASSOCIATED SFC HIGH SHOULD KEEP THE BULK OF THE FORECAST AREA RAIN FREE...BUT LAKE INDUCED INSTABILITY WILL KEEP THE POTENTIAL FOR SHOWERS INTACT FOR SITES EAST OF ROC AND IN PARTICULAR...EAST OF LK ONTARIO. MEANWHILE...H85 TEMPS AROUND +3C WILL TRANSLATE INTO A VERY COOL DAY AS AFTERNOON TEMPS WILL GENERALLY BE IN THE MID 60S. THE COOLEST CONDITIONS WILL BE IN THE SRN TIER WHERE SOME SPOTS WILL NOT RECOVER OUT OF THE 50S. FOR THURSDAY...A FULL LATITUDE BUT BROADER BASED H5 TROUGH WILL BE CENTERED OVER THE UPPER GREAT LAKES AS A DEEP CYCLONIC FLOW WILL BE FOUND OVER WESTERN AND NORTH CENTRAL NEW YORK. WHILE AN APPROACHING FRONTAL SYSTEM COULD TOUCH OFF SOME SHOWERS OVER THE FAR WESTERN COUNTIES...THE BULK OF THE DAY LOOKS TO BE RAIN FREE AT THIS POINT. && .AVIATION /16Z FRIDAY THROUGH TUESDAY/... DURING THE COURSE OF TODAY...A COLD FRONT WILL SLOWLY CROSS THE REGION FROM WEST TO EAST...WITH A 3-4 PERIOD OF SHOWERS AND ASSOCIATED MVFR CONDITIONS FOLLOWING ITS PASSAGE. FORECAST TIMING OF THIS HAS SLOWED DOWN A BIT FROM 12Z THINKING SO ADJUSTED TAFS ACCORDINGLY. THIS PERIOD OF SHOWERS SHOULD BEGIN ACROSS THE FAR WESTERN TAF SITES AROUND 19-20Z...KROC AROUND 20-21Z...AND KART AROUND 22-23Z. A FEW EMBEDDED THUNDERSTORMS ARE POSSIBLE OUT AHEAD OF THE MAIN AREA OF SHOWERS CLOSER TO INSTABILITY DEVELOPING OUT AHEAD OF THE FRONT. THE PROBABILITY OF THESE APPEARS TOO LOW TO MENTION GIVEN ONLY LIMITED AMOUNTS OF INSTABILITY. FOLLOWING THE END OF THE FRONTAL PRECIP...THE COMBINATION OF LINGERING LOW LEVEL MOISTURE AND LAKE INFLUENCES WILL KEEP A MIX OF MVFR TO LOW VFR CIGS IN PLACE TONIGHT...WITH THE LOWEST CIGS FOUND DOWNWIND /EAST-SOUTHEAST/ OF LAKES ERIE AND ONTARIO. WITH INCREASING AMOUNTS OF LAKE-DRIVEN INSTABILITY...SOME SCATTERED RAIN SHOWERS WILL ALSO BECOME POSSIBLE SOUTHEAST OF LAKE ONTARIO. OUTLOOK... SATURDAY...MVFR/VFR IN THE MORNING WITH SCATTERED SHOWERS SOUTHEAST OF LAKE ONTARIO...THEN IMPROVING TO VFR. SUNDAY AND MONDAY...VFR. TUESDAY...MAINLY VFR WITH A CHANCE OF SHOWERS/ASSOCIATED MVFR. && .MARINE... A COLD FRONT WILL CROSS THE LOWER GREAT LAKES TODAY...WITH A PERIOD OF SHOWERS AND POSSIBLE EMBEDDED THUNDERSTORMS IMMEDIATELY FOLLOWING THE FRONTAL PASSAGE. MORE IMPORTANTLY...WINDS WILL ALSO VEER TO NORTHWESTERLY AND FRESHEN BEHIND THE FRONT...BRINGING A PERIOD OF ADVISORY-LEVEL CONDITIONS TO LAKE ONTARIO THIS AFTERNOON AND TONIGHT. ON LAKE ERIE...WINDS AND WAVES WILL NOT STRENGTHEN QUITE AS MUCH...WITH CONDITIONS REMAINING A LITTLE BELOW ADVISORY LEVELS. AFTER THAT...HIGH PRESSURE WILL BUILD ACROSS THE LOWER LAKES THIS WEEKEND...BRINGING DIMINISHING WINDS AND WAVES. && .CLIMATE... ALL THREE OF OUR CLIMATE SITES REACHED AT LEAST 80F THURSDAY. THIS SAID...ALL THREE LOCATIONS CONTINUE TO RANK THIRD FOR GREATEST NUMBER OF 80F DAYS IN A YEAR. BUFFALO (SINCE 1944) 1 83 1949 2 82 1959 3 79 2012 AVG: 54 DAYS ROCHESTER (SINCE 1871) 1 91 1959 2 86 2007 3 85 2012 AVG: 59 DAYS WATERTOWN (SINCE 1949) 1 75 1949 2 73 1959 3 72 2012 AVG: 45 DAYS && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EDT SATURDAY FOR LOZ043-044. SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LOZ042. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EDT SATURDAY FOR LOZ045. && $$ SYNOPSIS...JJR NEAR TERM...JJR/SMITH SHORT TERM...RSH LONG TERM...RSH AVIATION...JJR/SMITH MARINE...JJR/SMITH CLIMATE...THOMAS/JJR
AREA FORECAST DISCUSSION
NWS BUFFALO NY
120 AM EDT FRI SEP 14 2012 .SYNOPSIS... HIGH PRESSURE SLIPPING OFF THE MID-ATLANTIC COASTLINE WILL CONTINUE FAIR WEATHER FOR ONE MORE NIGHT ACROSS THE REGION. A COLD FRONT WILL SLIDE ACROSS THE REGION ON FRIDAY ALONG WITH SOME SHOWERS. BEHIND THE COLD FRONT...SEASONABLY COOLER AIR WILL OVERSPREAD THE AREA FOR THE UPCOMING WEEKEND. && .NEAR TERM /THROUGH TODAY/... THROUGH LATE EVENING...WESTERN NEW YORK WAS MAINLY CLEAR...WITH MID AND HIGH CLOUDS JUST WORKING IN TO FAR WESTERN PORTIONS OF THE STATE. THIS CLOUD COVER SHOULD GRADUALLY MOVE FROM WEST TO EAST OVERNIGHT. RADAR SHOWS A FEW LIGHT SHOWERS ACROSS CENTRAL LAKE ERIE...AHEAD OF THE FRONT. MEANWHILE...A COLD FRONT WAS JUST ENTERING FAR WESTERN PORTIONS OF LAKE ERIE AT 1100 PM. THE FRONT ITSELF STILL IS DRY...BUT IT MAY PICK UP THE MOISTURE AND SHOWERS STREAMING ACROSS CENTRAL LAKE ERIE. THE HRRR AND 18Z NAM HAS THIS CLIPPING PERHAPS NIAGARA COUNTY DURING THE EARLY MORNING HOURS...WHICH SEEMS REASONABLE. ON FRIDAY THE COMPACT SHORTWAVE WILL BE DIGGING SOUTHWARD OVER THE WESTERN GREAT LAKES. NEAR THE SURFACE A COLD FRONT WILL BE CROSSING THE REGION FROM WEST TO EAST. RADAR CONFIRMS MODEL FORECASTS OF AN ANAFRONTAL PASSAGE TO THE COLD FRONT WITH THE BULK OF THE MOISTURE BEHIND THE FRONT WITH THE POTENT UPPER LEVEL SHORTWAVE PROVIDING THE LIFT. RADAR SHOWS A SOLID LINE OF RAIN SHOWERS...AND THE HRRR HOLDS THIS TOGETHER...BOTH OF WHICH INCREASES CONFIDENCE IN AT LEAST SOME MEASURABLE PRECIPITATION BEHIND THIS FRONT. BASED ON THIS...THE LATE EVENING UPDATE UPS POPS...AND NUDGES TIMING BACK JUST A TAD. EXPECT A BAND OF CLOUDS AND A NARROW BAND OF SHOWERS TO CROSS THE REGION...EARLY AFTERNOON IN WESTERN PORTIONS...MID-AFTERNOON ACROSS THE GENESEE VALLEY AND LATE AFTERNOON IN THE EASTERN LAKE ONTARIO REGION. IT IS POSSIBLE THAT SOME CLEARING REACHES WNY TOWARD SUNSET. THIS CLEARING MAY BE SHORT LIVED SOUTH OF LAKE ONTARIO AS COOLER AIR CONTINUES TO POUR OVER THE EASTERN GREAT LAKES ON A NORTHWEST FLOW WITH PATCHY LOW LEVEL STRATUS RETURNING ON FAVORABLE UPSLOPE AREAS SOUTH OF LAKE ONTARIO EARLY EVENING. THOUGH THERE HAS BEEN NO LIGHTNING ASSOCIATED WITH THESE SHOWERS UPSTREAM TODAY...WILL CONTINUE TO MENTION SLIGHT CHC FOR THUNDER AS MODELS DEPICT AN INCREASE IN INSTABILITY FRIDAY WITH UPWARDS TO 500 J/KG OF SBCAPE. WITH THE PROGRESSIVE NATURE OF THIS COLD FRONT EXPECT QPF TO GENERALLY BE A TENTH OR LESS TOWARDS THE SOUTH...WHILE FARTHER NORTH ACROSS THE NORTHERN NIAGARA FRONTIER AND EASTERN LAKE ONTARIO REGION UPWARDS OF TWO TENTHS OR SO OF AN INCH OF RAIN MAY FALL FRIDAY. TEMPERATURES TONIGHT WILL COOL INTO THE MID AND UPPER 50S TOWARDS THE GENESEE VALLEY AND AREAS EAST UNDER THE MAINLY CLEAR SKIES...WHILE AREAS TO THE WEST WILL FAVOR 60 OR ABOVE AS CLOUDS INCREASE. ON FRIDAY WITH THE COLD FRONT ACROSS WNY IN THE MORNING...EXPECT THE WARMEST AREAS TO BE ACROSS THE EASTERN LAKE ONTARIO REGION WHERE A FEW 80S WILL BE FOUND UNDER +13 TO +14C AT 850 HPA. TO THE WEST HIGHS WILL GENERALLY BE IN THE LOW AND MID 70S. && .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... COLD FRONT SHOULD BE EAST OF THE AREA FRIDAY NIGHT. SHARP MID LEVEL DRY INTRUSION WILL PUSH INTO THE AREA IN WAKE OF THE FRONT...AS WELL AS A MUCH COOLER AIR MASS. OVER-LAKE INSTABILITY WILL CERTAINLY BE INCREASING THROUGH THE NIGHT AND EARLY SATURDAY...AS 850 MB TEMPERATURES DROP TO NEAR +5C OR MAYBE A BIT COLDER. LINGERING LOW LEVEL MOISTURE AND CYCLONIC FLOW MAY BE ABLE TO OVERCOME ENTRAINMENT OF MID LEVEL DRY AIR TO DEVELOP SOME MINIMAL LAKE RESPONSE SOUTHEAST OF LAKE ONTARIO...BUT ANYTHING THAT DOES DEVELOP SHOULD BE SHORT LIVED AND LIGHT IN NATURE. HIGH PRESSURE WILL BUILD ACROSS THE REGION FOR FAIR WEATHER WEEKEND. THE AIR MASS LOOKS QUITE DRY...THEREFORE EXPECT A LARGE DIURNAL TEMPERATURE SWING. FAVORABLE RADIATIONAL COOLING CONDITIONS SATURDAY NIGHT/SUNDAY MORNING WILL ALLOW TEMPERATURES TO DROP INTO THE MID TO UPPER 30S INLAND. THIS WILL BRING A POTENTIAL FROST TO SOME LOCATIONS ALONG THE SOUTHERN TIER AND EAST OF LAKE ONTARIO. SATURDAY LOOKS TO BE THE COOLEST WEEKEND DAY WITH MOST HIGHS IN THE MID TO UPPER 60S. WARM AIR ADVECTION DEVELOPS BY SUNDAY AS THE HIGH STARTS TO SHIFT EAST...THIS SHOULD ALLOW TEMPERATURES TO REBOUND BACK INTO THE UPPER 60S TO LOWER 70S. && .LONG TERM /MONDAY THROUGH THURSDAY/... SOME MODEL DISCREPANCIES DEVELOP BY MONDAY. THE GFS IS MUCH FASTER THAN THE ECMWF/CANADIAN WITH THE SHORTWAVE ENERGY LIFTING OUT OF THE SOUTHERN PLAINS...WHILE SLOWER SOLUTIONS ALLOWS FOR SOME PHASING OF NORTHERN AND SOUTHERN STREAM WAVES. AT THIS POINT...WILL OFFER A MODEL BLEND AND BRING SOME LIMITED PROBABILITIES INTO THE AREA AHEAD OF THE COLD FRONT FOR MONDAY. THE UPPER LEVEL FLOW LOOKS TO BECOME DEEPLY AMPLIFIED HEADING INTO THE MIDDLE OF NEXT WEEK...WITH AN IMPRESSIVE WESTERN CONUS RIDGE AND CENTRAL PLAINS/GREAT LAKES TROUGH EVOLVING. LATEST MEDIUM RANGE MODELS AND ENSEMBLES IN GENERAL AGREEMENT BRINGING SHARP COLD FRONT LATER TUESDAY INTO WEDNESDAY. DECENT POTENTIAL FOR SHOWERS WITH THE FRONTAL PASSAGE FOLLOWED BY A SHOT OF RATHER CHILLY AIR. THERE LOOKS TO BE SOME AIRMASS MODIFICATION...BUT WEDNESDAY STILL COULD BE RATHER COOL WITH SOME LOCATIONS STRUGGLING TO GET OUT OF THE 50S. PATTERN LOOKS PROGRESSIVE WITH WARM AIR ADVECTION PATTERN RESUMING THURSDAY AHEAD OF NEXT APPROACH FRONTAL ZONE. && .AVIATION /05Z FRIDAY THROUGH TUESDAY/... THROUGH 12Z...VFR CONDITIONS WILL PREVAIL...WITH MID AND HIGH CLOUD COVER GRADUALLY INCREASING FROM WEST TO EAST IN ADVANCE OF A SLOWLY APPROACHING COLD FRONT. IN THE PREDAWN HOURS...A FEW SCATTERED LIGHT SHOWERS WILL BE POSSIBLE ACROSS FAR WESTERN NEW YORK IN ASSOCIATION WITH THE FRONT...HOWEVER EVEN IF THESE MATERIALIZE THEY SHOULD HAVE NO IMPACT ON AVIATION CONCERNS. DURING THE COURSE OF TODAY...THE AFOREMENTIONED FRONT WILL SLOWLY CROSS THE REGION FROM WEST TO EAST...WITH A 3-4 PERIOD OF SHOWERS AND ASSOCIATED MVFR CONDITIONS FOLLOWING ITS PASSAGE. THIS PERIOD OF SHOWERS SHOULD BEGIN ACROSS THE FAR WESTERN TAF SITES AROUND 18Z...KROC AROUND 19Z...AND KART AROUND 21Z. WHILE A FEW EMBEDDED THUNDERSTORMS ALSO CANNOT BE RULED OUT BEHIND THE FRONT...THE PROBABILITY OF THESE APPEARS TOO LOW TO MENTION GIVEN ONLY LIMITED AMOUNTS OF INSTABILITY. FOLLOWING THE END OF THE FRONTAL PRECIP...THE COMBINATION OF LINGERING LOW LEVEL MOISTURE AND LAKE INFLUENCES WILL KEEP A MIX OF MVFR TO LOW VFR CIGS IN PLACE TONIGHT...WITH THE LOWEST CIGS FOUND DOWNWIND /EAST-SOUTHEAST/ OF LAKES ERIE AND ONTARIO. WITH INCREASING AMOUNTS OF LAKE-DRIVEN INSTABILITY...SOME SCATTERED RAIN SHOWERS WILL ALSO BECOME POSSIBLE SOUTHEAST OF LAKE ONTARIO. OUTLOOK... SATURDAY...MVFR/VFR IN THE MORNING WITH SCATTERED SHOWERS SOUTHEAST OF LAKE ONTARIO...THEN IMPROVING TO VFR. SUNDAY AND MONDAY...VFR. TUESDAY...MAINLY VFR WITH A CHANCE OF SHOWERS/ASSOCIATED MVFR. && .MARINE... HIGH PRESSURE SLIPPING OFF THE MID ATLANTIC COASTLINE WILL GIVE ONE MORE QUIET NIGHT ON THE LAKES AND RIVERS. ON FRIDAY A COLD FRONT WILL CROSS THE REGION FROM WEST TO EAST WITH A NARROW BAND OF SHOWERS...PRIMARILY BEHIND THE FRONT. AS WINDS SHIFT TO NORTHWEST AND WITH SHARP COOLING ALOFT EXPECT WAVES TO INCREASE LATER FRIDAY AND FRIDAY NIGHT WITH SMALL CRAFT CONDITIONS ON CENTRAL AND EASTERN PORTIONS OF LAKE ONTARIO. HAVE THEREFORE ISSUED A SCA FOR THESE SECTIONS OF LAKE ONTARIO. WITH THE BOUNDARY LAYER FLOW MORE PERPENDICULAR TO LAKE ERIE FRIDAY EVENING AND NIGHT WAVES WILL INCREASE...THOUGH LIKELY REMAINING BELOW SMALL CRAFT CONDITIONS. A STEADY NORTHWEST FLOW WILL CONTINUE TO START THE WEEKEND THOUGH WINDS AND WAVES SHOULD REMAIN BELOW SMALL CRAFT CRITERIA. && .CLIMATE... ALL THREE OF OUR CLIMATE SITES REACHED AT LEAST 80F THURSDAY. THIS SAID...ALL THREE LOCATIONS CONTINUE TO RANK THIRD FOR GREATEST NUMBER OF 80F DAYS IN A YEAR. BUFFALO (SINCE 1944) 1 83 1949 2 82 1959 3 79 2012 AVG: 54 DAYS ROCHESTER (SINCE 1871) 1 91 1959 2 86 2007 3 85 2012 AVG: 59 DAYS WATERTOWN (SINCE 1949) 1 75 1949 2 73 1959 3 72 2012 AVG: 45 DAYS && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 6 AM EDT SATURDAY FOR LOZ043-044. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EDT SATURDAY FOR LOZ045. && $$ SYNOPSIS...THOMAS NEAR TERM...APFFEL/THOMAS SHORT TERM...TMA LONG TERM...TMA AVIATION...JJR MARINE...APFFEL/THOMAS CLIMATE...THOMAS/JJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
925 PM EDT SAT SEP 15 2012 .SYNOPSIS... A WEAK COLD FRONT WILL STALL OVER SOUTH CAROLINA TONIGHT AND SUNDAY...AS HIGH PRESSURE HIGH PRESSURE NOSES IN FROM THE NORTH. THE FRONT WILL RETURN AS A WARM FRONT LATE MONDAY INTO TUESDAY WITH THE APPROACH OF A STRONG STORM SYSTEM. && .NEAR TERM /THROUGH SUNDAY NIGHT/... AS OF 925 PM SATURDAY... TWO LOCALIZED AREAS OF CONCERN THIS EVENING. WEAK LOW LEVEL CONFLUENCE ALONG A STALLED SURFACE BOUNDARY NEAR THE SOUTH CAROLINA BORDER HAD INITIATED AND SUSTAINED A FEW SHOWERS WITH MOST OF THE SHOWERS CONCENTRATED IN VICINITY OF LAURINBURG. DOPPLER RADAR ESTIMATES OF 1-1.5 INCHES FROM THESE SLOW MOVING SHOWERS NORTH OF LAURINBURG SINCE 630PM. THREAT FOR ISOLATED SHOWERS WILL LIKELY PERSIST ALONG THIS SURFACE FEATURE THROUGH THE REMAINDER OF THE EVENING. 00Z 925MB ANALYSIS DEPICTS ESE 10KT FLOW AT GSO WITH WEAK WEST FLOW AT RNK. 18Z NAM VERIFIED BEST IN THIS REGION IN REGARDS TO WIND VELOCITY. NAM CONTINUES TO DEPICT DECENT SPEED CONVERGENCE OVERNIGHT THROUGH EARLY SUNDAY. BASED ON PERSISTENT SHOWERS OCCURRING WEST OF KINT...PLAUSIBLE THAT SHOWERS MAY MIGRATE INTO THE NW PIEDMONT OVERNIGHT. 23Z RUN OF THE RAP SUGGEST SHOWERS A GOOD POSSIBILITY INT HE TRIAD REGION AFTER MIDNIGHT. THUS HAVE INTRODUCED/INCREASED POPS IN THE NW PIEDMONT OVERNIGHT. SLIGHTLY DRIER COOLER AIR MAKING SOME INROADS INTO THE NORTHERN COASTAL PLAIN AND FAR NE PIEDMONT THIS EVENING. WITH THE CHANGE IN AIR MASS AND MOSTLY CLEAR-PARTLY CLOUDY SKIES THROUGH MOST OF THE NIGHT...EXPECT COOLER MIN TEMPS IN THIS REGION. MEANWHILE THICKER CLOUDS IN THE WEST-SOUTHWEST WILL HOLD IN SOME OF THE HEAT ATTAINED EARLIER TODAY. MIN TEMPS MID-UPPER 50S NE TO LOW-MID 60S SW. -WSS MODELS HAVE BEEN TRENDING MORE MOIST SUNDAY AND SUNDAY NIGHT. THIS APPEARS TIED TO THE ISENTROPIC LIFT THAT IS FORECAST TO RAPIDLY INCREASE BETWEEN 12Z-18Z... ESPECIALLY OVER THE SANDHILLS INTO THE PIEDMONT AND MOUNTAINS. THE NAM IS MORE EMPHATIC WITH THE LIFT AND THE STRENGTH OF THE LIFT... GENERATING QPF BETWEEN 0.25 AND 0.50 OF AN INCH SUNDAY AFTERNOON AND EVENING. THE GFS/EC ARE WEAKER WITH THE LIFT BUT STILL INDICATE A SLOWER... YET STEADY INCREASE IN CLOUDS THEN LIGHT RAIN CHANCES ESPECIALLY IN THE WEST AND NORTH SUNDAY AFTERNOON AND EVENING. WE WILL BEGIN TO TREND BACK TOWARD THE MORE MOIST AND WETTER FORECAST (ESPECIALLY OVER THE PIEDMONT) DURING SUNDAY... SPREADING EAST SUNDAY AFTERNOON AND NIGHT. THE LOW LEVEL STABILITY IS FORECAST TO INCREASE SUNDAY AS CLOUDS INCREASE AND CEILINGS LOWER... LIGHT RAIN INCREASES... AND THE SURFACE FLOW BACKS TO THE NE-N (PIEDMONT DAMMING DEVELOPMENT). WE WILL HAVE TO GO LOWER THAN MOS FOR HIGHS... ESPECIALLY WEST... FAVORING THE MUCH COOLER MET GUIDANCE THERE. IN THE EAST... A SLOWER LOWERING OF THE CEILINGS AND LATE ARRIVAL/LOWER RAIN CHANCES SUGGEST A TIGHTENING THERMAL GRADIENT... WITH POTENTIAL FOR NEAR 80 FROM FAY TO GSB AND 60S BACK IN THE WESTERN PIEDMONT. THIS SUGGESTS THAT A FAIRLY DISTINCT WARM FRONT SHOULD SET UP FROM SW-NE ACROSS THE SOUTHERN AND EASTERN PIEDMONT SUNDAY NIGHT. THIS IS THE REGION WHERE WAA/ISENTROPIC LIFT SHOULD BE STRONGEST SUNDAY NIGHT... AND WHERE THE HIGHEST POP/QPF WILL LIKELY BE. THIS IS ALSO WHERE THE LOWER CEILINGS AND VISIBILITIES (ADVERSE AVIATION CONDITIONS ARE EXPECTED). SENSIBLE WEATHER SUNDAY AND SUNDAY NIGHT... CLOUDY IN THE WEST AND MOSTLY CLOUDY EAST. LIGHT RAIN LIKELY WEST AND NORTH ESPECIALLY IN THE AFTERNOON. HIGHS 65-70 NW... RANGING TO NEAR 80 SE. OCCASIONAL LIGHT RAIN SUNDAY NIGHT WEST AND NORTH... A CHANCE OF SHOWERS EAST AND SOUTH. LOWS 55-60 NW RANGING TO MID 60S SE. IT APPEARS ISOLATED THUNDER IS POSSIBLE BUT INSTABILITY SHOULD BE LACKING INTO SUNDAY NIGHT. WE WILL CONTINUE TO FINE TUNE THIS PART OF THE FORECAST AS THE EVOLUTION OF THE WARM FRONT AND SURFACE LOW PRESSURE OCCURS SUNDAY. -BADGETT && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 200 PM SATURDAY... OVERVIEW: A FAIR AMOUNT OF UNCERTAINTY PERSISTS WITH REGARD TO THE SPECIFICS OF THE FORECAST (TIMING...RAINFALL AMOUNTS...SEVERE THREAT) IN THIS PERIOD. HOWEVER...OVERALL CHANCES FOR RAIN REMAIN HIGH...ESPECIALLY OVER WESTERN PORTIONS OF THE STATE. UNCERTAINTY IN THE EVOLUTION OF THE UPPER LEVEL PATTERN (AND ATTENDANT SURFACE PATTERN) OVER THE EASTERN CONUS IS DUE TO SEVERAL FACTORS. STALLED SOUTHERN STREAM SHORTWAVE ENERGY OVER THE DESERT SOUTHWEST AND LOWER MIDWEST IS EXPECTED TO BECOME PROGRESSIVE BY SUNDAY NIGHT...TRACKING THROUGH THE LOWER MS RIVER VALLEY INTO THE DEEP SOUTH BY MON/MON NIGHT. AT THE SAME TIME...AN AMPLIFYING NORTHERN STREAM TROUGH IS PROGGED TO DIG SOUTHEAST FROM CANADA INTO THE UPPER MIDWEST SUNDAY NIGHT... FURTHER AMPLIFYING AS IT DIGS SOUTHEAST INTO THE OH/TN VALLEYS MON NIGHT/TUESDAY. IN ADDITION TO CONTINUED UNCERTAINTY IN THE EVOLUTION OF THE NORTHERN STREAM TROUGH EMANATING FROM DATA SPARSE REGIONS OF THE NORTHWEST TERRITORIES/NUNAVUT CANADA...MATTERS ARE FURTHER COMPLICATED BY THE POTENTIAL INTERACTION BETWEEN THE YET-TO-EVOLVE NORTHERN STREAM TROUGH AND THE SOUTHERN STREAM SHORTWAVE ENERGY. FORECAST UNCERTAINTY IS EVIDENCED WELL BY THE RELATIVELY POOR MODEL-TO-MODEL AND RUN-TO-RUN CONTINUITY THE PAST FEW DAYS...WITH VARYING SOLUTIONS ON THE EVOLUTION OF THE SYNOPTIC PATTERN AND TIMING/LOCATION/TRACK OF THE PARENT SURFACE LOW...COLD FRONT (AND PERHAPS MESOSCALE LOWS ALONG THE FRONT) OVER THE EASTERN CONUS. LATEST MODEL TRENDS: 00Z AND 12Z MODEL GUIDANCE HAS CONTINUED TO SLOW DOWN THE ARRIVAL OF THE FRONT OVER CENTRAL NC...WITH THE NAM/GFS INDICATING FROPA OCCURRING TUESDAY EVENING...AND THE 00Z ECMWF WEDNESDAY MORNING. PRECIPITATION CHANCES: CONFIDENCE REMAINS HIGH WITH REGARD TO WIDESPREAD RAIN (POTENTIALLY HEAVY) OVER CENTRAL NC IN ASSOC/W THIS SYSTEM. ALTHOUGH TIMING HAS BEEN AN ISSUE THUS FAR...IT DOES APPEAR THAT MODEL GUIDANCE HAS BEGUN TO CLUSTER TOWARD FROPA OCCURRING LATE TUE/TUE NIGHT...AND AT THIS TIME EXPECT THE BEST CHANCE FOR WIDESPREAD RAIN /HEAVY AT TIMES/ ON TUESDAY...WITH RAINFALL AMOUNTS IN THE 0.50-1.00" RANGE... THOUGH LOCALLY HIGHER AMOUNTS WILL BE POSSIBLE...PRIMARILY IN THE WEST/NW PIEDMONT. ANTICIPATE THAT CHANCES FOR RAIN WILL END FROM WEST-EAST WITH THE FRONTAL PASSAGE TUE EVE/NIGHT. SEVERE THREAT: THE THREAT FOR SEVERE WEATHER APPEARS TO HAVE INCREASED WITH THE 12Z MODEL RUNS...WHICH PLACE CENTRAL NC IN THE WARM SECTOR AHEAD OF THE APPROACHING FRONT TUE AFT/EVE. MODEL GUIDANCE IS FAIRLY UNANIMOUS IN SHOWING A 40-KT SOUTHERLY LLJ OVER THE WARM SECTOR IN THE PRESENCE OF STRENGTHENING DEEP-LAYER SHEAR...EXCELLENT BOUNDARY LAYER MOISTURE...AND STRONG SYNOPTIC FORCING. ALTHOUGH THE OVERALL SETUP WILL BE OF THE HIGH SHEAR/LOW CAPE VARIETY GIVEN EXTENSIVE CLOUD COVER AND WEAK/MOIST ADIABATIC MID-LEVEL LAPSE RATES...THE POTENTIAL FOR FAVORABLE DIURNAL TIMING IN ASSOC/W AN AMPLIFIED PATTERN THIS TIME OF YEAR IS SOMEWHAT DISCONCERTING. GIVEN THE AFOREMENTIONED FORECAST UNCERTAINTY IT REMAINS DIFFICULT TO PIN DOWN BOTH THE TIMING AND MAGNITUDE OF THE SEVERE THREAT. HOWEVER...GIVEN THE EXPECTED KINEMATIC/THERMODYNAMIC ENVIRONMENT...ISOLD TORNADOES REMAIN A DISTINCT POSSIBILITY. -VINCENT && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 200 PM SATURDAY... WEDNESDAY THROUGH SATURDAY: EXPECT HEIGHT RISES ALOFT AND HIGH PRESSURE BUILDING INTO THE AREA WED/THU/FRI...WITH CLEARING SKIES AND TEMPS SLIGHTLY COOLER THAN NORMAL. A SLOWLY DEEPENING UPPER LEVEL TROUGH IS EXPECTED OVER THE GREAT LAKES NEXT WEEKEND...WHICH WOULD PUSH ANOTHER FRONT TOWARD THE SOUTHERN APPALACHIANS SAT/SUN. -VINCENT && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... AS OF 8 PM SATURDAY... VFR CONDITIONS ARE EXPECTED TO CONTINUE THIS EVENING... WITH VFR CONDITIONS GENERALLY EXPECTED TO CONTINUE OVERNIGHT AS MID AND HIGH LEVEL CLOUD COVER CONTINUES TO STREAM ACROSS THE AREA. HOWEVER... WE MAY SEE SOME MVFR VISBYS AT KFAY AND KRWI. GIVEN THE INCREASE IN MID AND UPPER LEVEL MOISTURE CONFIDENCE IS NOT VERY HIGH THOUGH (FOR SUB VFR CONDITIONS). THUS... WILL JUST GO WITH A TEMPO GROUP FOR THE PRE-DAWN HOURS OF SUNDAY MORNING FOR MVFR VISBYS AT KFAY AND KRWI. LOW LEVEL FLOW IS EXPECTED TO BECOME MORE EAST/SOUTHEASTERLY ON SUNDAY... WHICH WILL HELP TO CREATE/BRING LOWER CIGS AND SOME RAIN POSSIBLY TO THE WESTERN PORTIONS OF CENTRAL NC. OVERALL CONFIDENCE IN THE CIGS IS RATHER LOW THOUGH... WITH SOME GUIDANCE SHOWING IFR CIGS AT KGSO/KINT BY AT LEAST MID MORNING. HOWEVER... DO NOT PLAN TO GO QUITE THAT EXTREME YET. FOR NOW... WILL SHOW MVFR CONDITIONS AND RAIN DEVELOPING AT KGSO/KINT BY MIDDAY... LOWERING TO AROUND A THOUSAND FEET LATE IN PERIOD (~21Z). FURTHER EAST EXPECT LESS OF AN IMPACT WITH THIS TAF ISSUANCE FOR ADVERSE AVIATION CONDITIONS. FOR NOW WILL ONLY SHOW KRDU DROPPING INTO THE MVFR CATEGORY BY LATE IN THE DAY... WITH POSSIBLY SOME LIGHT RAIN... WITH VFR CONDITIONS AT KRWI AND KFAY AT 12Z SUNDAY. LATE SUNDAY INTO TUESDAY... A MOISTENING SOUTHERLY FLOW WILL BRING LOWERING CIGS FROM MVFR TO IFR LATE SUNDAY INTO MONDAY MORNING. VSBYS WILL BE REDUCED BY LIGHT RAIN AND FOG IN THE KINT/KGSO AREAS LATE SUNDAY AND SUNDAY NIGHT... SPREADING EAST TO KFAY AND KRDU SUNDAY NIGHT. THE MAIN STORM SYSTEM APPROACHING FROM THE SW WILL BRING LIFR TO IFR CIGS/VSBYS WITH SHOWERS AND FOG LATE MONDAY INTO TUESDAY. THERE IS A CHANCE OF THUNDERSTORMS TUESDAY. A RETURN TO VFR CIGS/VSBYS IS EXPECTED BEHIND THE MAIN COLD FRONT AFTER 12Z WEDNESDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT NEAR TERM...WSS/BADGETT SHORT TERM...VINCENT LONG TERM...VINCENT AVIATION...BSD/BADGETT
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1234 PM FRI SEP 14 2012 .SYNOPSIS... WEAKENING HIGH PRESSURE TO OUR NORTH WILL REMAIN IN PLACE THROUGH SATURDAY. A COLD FRONT WILL DROP INTO THE AREA SUNDAY BUT SHOULD QUICKLY DISSIPATE. LOW PRESSURE DEVELOPING ALONG THE GULF COAST MONDAY WILL MOVE THROUGH THE WESTERN CAROLINAS TUESDAY...DRAGGING A COLD FRONT ACROSS THE EASTERN CAROLINAS EARLY WEDNESDAY. HIGH PRESSURE WILL BUILD TO THE COAST FROM THE WEST ON THURSDAY... BRINGING A RETURN TO DRY WEATHER. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM FRIDAY...THE SEABREEZE BOUNDARY FROM WILMINGTON NORTHEAST ALONG HIGHWAY 17 IS LIGHTING UP WITH LIGHT SHOWERS. VISIBLE SATELLITE IMAGERY SHOWS THE CUMULUS FIELD IS VERY AGITATED INLAND ACROSS BRUNSWICK...COLUMBUS AND BLADEN COUNTIES AS WELL. I`VE ADDED SMALL POPS FOR ISOLATED SHOWERS ACROSS THIS AREA BASED ON SATELLITE IMAGERY AND THE LATEST FEW HRRR RUNS THAT SHOWS CONVECTIVE POTENTIAL FOCUSING HERE OVER THE NEXT 3-4 HOURS. THE PATCH OF MORNING LOW CLOUDS ACROSS HORRY...BRUNSWICK AND COLUMBUS COUNTIES LEFT A HOLE IN THE CUMULUS FIELD DUE TO A DELAYED START TO WARMING SURFACE TEMPERATURES...AND THIS MAY SERVE TO REDUCE CONVECTIVE POTENTIAL HERE WITH THE RELATIVELY SHORT DAY LENGTHS THIS TIME OF YEAR. NO SIGNIFICANT CHANGES TO HIGH TEMPERATURES OR DEWPOINTS ARE NEEDED. PREVIOUS DISCUSSION FROM 1000 AM FOLLOWS... A WEAKENING SURFACE RIDGE EXTENDS ACROSS THE MID-ATLANTIC STATES WITH NORTHEAST WINDS CONTINUING ACROSS THE CAROLINAS. IN THE UPPER LEVELS A WEAK UPPER TROUGH MOVING ACROSS THE SOUTHERN APPALACHIANS HAS DEVELOPED AN EXPANSIVE MID-LEVEL CLOUD CANOPY EXTENDING FROM SOUTHERN VIRGINIA ACROSS THE WESTERN AND CENTRAL CAROLINAS AND INTO NORTH GEORGIA. MODEL INITIALIZATION WITH THIS MID-LEVEL MOISTURE IS TERRIBLE: NO MODEL "SEES" ANY OF THIS MOISTURE IN THE 12K-16KFT LAYER. THESE CLOUDS SHOULD CONTINUE PUSHING NORTHEASTWARD...PRODUCING PARTLY CLOUDY SKIES (PERHAPS MOSTLY CLOUDY FOR A TIME?) ACROSS MOST OF OUR FORECAST AREA AWAY FROM THE IMMEDIATE COAST. AS HAS BEEN THE STORY FOR THE PAST THREE DAYS...THE AIRMASS CONTINUES TO MODIFY WITH ATLANTIC`S INFLUENCE INCREASING ITS IMPACT ON THE AIRMASS COMING ONSHORE. I THINK IT`S SAFE TO CALL THIS A SUBTROPICAL AIRMASS NOW WITH DEWPOINTS BACK IN THE UPPER 60S AND OFFSHORE AIR TEMPERATURES IN THE UPPER 70S. THE MID-LEVEL CLOUD COVER INLAND SHOULD HAVE LITTLE IMPACT ON OUR HIGHS TODAY AND WE`RE ANTICIPATING 82-85 DEGREES AWAY FROM THE BEACHES. WITH STEEP LOW LEVEL LAPSE RATES AND LOADS OF LOW-LEVEL MOISTURE A LOW CUMULUS SHOULD DEVELOP IN THE NEXT FEW HOURS. SOME OF THESE WITHIN 30-40 MILES OF THE COAST COULD GROW INTO SMALL SHOWERS...AND I`LL MAINTAIN THE 20 POP FOR THIS POTENTIAL. THE STEERING FLOW ALOFT IS RATHER WEAK AND ONLY A SLIGHT WESTWARD DRIFT OF ANY SHOWERS IS EXPECTED. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...WEAKENING COLD FRONT WILL MOVE INTO THE AREA FROM THE NORTHWEST LATE SAT. LACK OF UPPER LEVEL SUPPORT...THE PARENT LOW WILL BE IN EASTERN CANADA...AND ABUNDANT DRY AIR WILL KEEP ITS PASSAGE DRY. AHEAD OF THE FRONT THE DRY AIR COMBINED WITH WEAK MID LEVEL SUBSIDENCE WILL LIMIT CONVECTION SAT AFTERNOON. WESTERLY FLOW ALOFT SAT NIGHT WILL ADVECT DEEPER MOISTURE OVER THE LOWER MS VALLEY INTO THE REGION FOR SUN. THE DEEP MOISTURE COMBINED WITH DIURNAL HEATING...REMNANTS OF DISSIPATING COLD FRONT...AND PASSAGE OF SHORTWAVE SHOULD GENERATE SOME DEEPER CONVECTION SUN. HOWEVER...HAVE LOW CONFIDENCE IN THE LOCATION AND STRENGTH OF SHORTWAVE AND GIVEN THE FLAT PATTERN ALOFT WILL HOLD ONTO SLIGHT CHANCE POP FOR NOW. LOW LEVEL RETURN FLOW STARTS TO DEVELOP SUN NIGHT AS AS SURFACE HIGH TO THE NORTH SLIPS OFF THE MID-ATLANTIC COAST. TEMPERATURES WILL BE NEAR CLIMO ON SAT AND SAT NIGHT FALLING SLIGHTLY BELOW SUN AND SUN NIGHT. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 3 AM FRIDAY...SOUTHERN STREAM SHORTWAVE TROUGH EMERGING FROM EAST TX AT THE START OF THE PERIOD WILL BE ACCELERATED NORTHEAST TUE BY AMPLIFYING 5H TROUGH OVER THE MS VALLEY. STILL SEEING SOME DIFFERENCES WITHIN THE MEDIUM RANGE GUIDANCE BUT OVERALL AGREEMENT IS GOOD. MON/TUE LOOK WET WITH DEEP SOUTH TO SOUTHWEST FLOW PUSHING PLENTY OF GULF MOISTURE OVER THE SOUTHEAST. IN ADDITION DIVERGENT FLOW ALOFT AND STRONG LOW LEVEL JETTING DEVELOP LATE MON AND CONTINUE FOR MUCH OF TUE. A SERIES OF SHORTWAVES WILL MOVE ACROSS THE SOUTHEAST...ENHANCING CONVECTION AS THEY APPROACH AND SUPPRESSING ACTIVITY AS THEY EXIT. TIMING HOWEVER REMAINS DIFFICULT...THUS POP FORECAST WILL BE TEMPERED AND LESS PRECISE. HIGHLY AMPLIFIED 5H TROUGH PUSHES COLD FRONT THROUGH THE AREA TUE NIGHT OR WED WITH DRIER/COOLER AIR TRYING TO BUILD IN BEHIND THE BOUNDARY. LATE NEXT WEEK 5H TROUGHING SETS UP OVER THE EASTERN HALF OF THE COUNTRY. IF THE FRONT ENDS UP PARALLEL TO THE FLOW ALOFT WITH A MECHANISM TO EJECT IT NORTHEAST IT WOULD REMAIN STALLED JUST OFF THE SOUTHEAST COAST THROUGH THE END OF THE PERIOD. TEMPERATURES WILL BE NEAR TO SLIGHTLY BELOW CLIMO THROUGH THE PERIOD...LOW TO MID 80S AND LOW TO MID 60S. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AS OF 18Z...ISOLATED SHOWERS ALONG THE SEA BREEZE BOUNDARY THIS AFTERNOON WILL PUSH ACROSS THE WILMINGTON VICINITY AND MAY AFFECT CRE/MYR AND POSSIBLY LBT BY LATE AFTERNOON. VERY ISOLATED COVERAGE ONLY WARRANTS A VCSH. SURFACE WINDS WILL BE FAIRLY LIGHT TODAY SOUTH OF A WEAKENING HIGH PRESSURE RIDGE. TONIGHT...GOOD RADIATIONAL COOLING CONDITIONS WILL BRING FOG INTO THE PICTURE LATE. MODELS ARE FAVORING THE INLAND TERMINALS WITH MORE FAVORABLE LOW-LEVEL MOISTURE PROFILES. WILL GO WITH INTERMITTENT IFR THERE. SATURDAY...A REINFORCING PUSH OF HIGH PRESSURE MOVES IN ALONG A WASHED OUT COLD FRONT. WINDS WILL BE LIGHT AND MAINLY NORTHEASTERLY. THE EXTENDED OUTLOOK THROUGH WEDNESDAY...AN INCREASED CHANCE OF PRECIPITATION SUNDAY. SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS MONDAY THROUGH WEDNESDAY...MOST NUMEROUS TUESDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM FRIDAY...NORTHEAST WINDS CONTINUE IN THE 10-13 KNOT RANGE ON THE NOON OBSERVATIONS. THERE ALSO HAVE BEEN NO CHANGE IN SEA HEIGHTS AT THE AREA BUOYS. NO CHANGES IN THE FORECAST ARE NEEDED. PREVIOUS DISCUSSION FROM 1000 AM FOLLOWS... A WEAKENING SURFACE RIDGE REMAINS NORTH OF THE CAROLINAS WITH NORTHEAST WINDS COVERING THE AREA. THE FLOW BUCKLES ALONG THE GEORGIA AND SOUTHERN SOUTH CAROLINA COAST WHERE A WEAK COASTAL TROUGH APPEARS TO HAVE DEVELOPED. THIS FEATURE SHOULD REMAIN TOO FAR SOUTH OF OUR FORECAST AREA FOR ANY IMPACTS LOCALLY. NORTHEAST WINDS MAY BEND AROUND TO THE EAST LATER TODAY WITH A WEAK SEABREEZE...BUT THERMAL CONTRASTS FROM THE MARINE ENVIRONMENT TO INLAND SHOULD BE TOO WEAK FOR ANY SIGNIFICANT INCREASE IN WIND SPEEDS. WINDS CURRENTLY AVERAGE 10-13 KNOTS AND SHOULD REMAIN THERE THROUGH THE DAY. SEAS RANGE FROM 3-4 FT AT THE OFFSHORE BUOYS IN A JUMBLED MIX OF 4-7 SECOND LOCAL WIND WAVES AND A MUCH SMALLER 10-13 SECOND LONG PERIOD SWELL ADVECTING IN FROM THE DEEP ATLANTIC. ISOLATED SHOWER ACTIVITY OFFSHORE EAST OF CAPE FEAR SHOULD WEAKEN AS IT APPROACHES THE COAST...BUT WE MAY GENERATE NEW SHOWERS ALONG THE SEABREEZE BOUNDARY THIS AFTERNOON THAT MAY AFFECT THE BEACHES AND ADJACENT NEARSHORE WATERS. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...LIGHT NORTHEAST FLOW EARLY SAT WILL BRIEFLY BECOME SOUTHERLY AHEAD OF WEAK COLD FRONT. FRONT PUSHES SOUTHEAST OF THE WATERS SAT NIGHT INTO SUN WITH A BRIEF BUT NOTICEABLE NORTHEAST SURGE BEHIND IT ON SUN. HIGH PRESSURE BUILDING IN BEHIND THE FRONT WILL SLIDE OFF THE MID-ATLANTIC COAST SUN NIGHT WITH NORTHEAST FLOW GRADUALLY VEERING TO EASTERLY. SPEEDS WILL BE UNDER 10 KT FOR MUCH OF THE PERIOD WITH SEAS 2 TO 4 FT. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 3 AM FRIDAY...LIGHT SOUTHEAST FLOW AT THE START OF THE PERIOD INCREASE IN SPEEDS MON IN RESPONSE TO TIGHTENING PRESSURE GRADIENT. SPEEDS START OUT AROUND 10 KT BUT WILL END UP 10 TO 15 KT MON AFTERNOON. SPEEDS INCREASE TO 15 TO 20 KT BY TUE AND VEER TO SOUTHWESTERLY. SEAS 2 TO 4 FT MON WILL BUILD IN RESPONSE TO INCREASE IN SOUTHERLY FLOW. TUE SEAS REACH 3 TO 5 FT WITH SOME ISOLATED 6 FT POSSIBLE NEAR 20 NM. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...TRA SHORT TERM...III LONG TERM...III AVIATION...43
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
936 AM EDT FRI SEP 14 2012 .SYNOPSIS... HIGH PRESSURE WILL EXTEND OVER THE AREA FROM THE NORTHEAST TODAY WITH ONSHORE FLOW PRODUCING SCATTERED SHOWERS FROM OFFSHORE. A WEAK COLD FRONT WILL MOVE THROUGH THE AREA FROM THE NORTHWEST LATE TONIGHT AND SATURDAY. HIGH PRESSURE WILL BUILD IN SATURDAY NIGHT AND EXTEND OVER THE AREA THROUGH SUNDAY NIGHT. A STRONG COLD FRONT WILL APPROACH FROM THE WEST TUESDAY AND MOVE THROUGH WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 930 AM FRIDAY...EASTERN NORTH CAROLINA CURRENT SITS IN A SHEAR AXIS BETWEEN UPPER LOW OFFSHORE AND DEEPENING MID-LEVEL TROUGH OUT NEAR THE MOUNTAINS. WITH DEEP ONSHORE FLOW AND A MUCH MORE MOIST ENVIRONMENT THAT PREVIOUS DAYS...SHOWERS HAVE BLOSSOMED NEAR THE COAST AND HAVE MOVED INLAND FROM THE PAMLICO SOUND NORTH. EXPECT ADDITIONAL SHOWERS TO AFFECT THE SOUTHERN COUNTIES AND WILL CONTINUE WITH CHANCE POPS THROUGH MOST OF THE DAY PER LATEST NAM12 WHICH SEEMS TO HAVE A BETTER HANDLE ON THE CURRENT SITUATION THAT THE RAP OR GFS. NO OTHER MAJOR CHANGES AT THIS TIME. && .SHORT TERM / SATURDAY THROUGH 6 AM SATURDAY/... AS OF 330 AM FRIDAY...SHRT WV TROF MOVING ACROSS N OF AREA WILL RESULT IN WEAK SFC COLD FRONT MOVING IN FROM NW OVERNIGHT...BREAKING DOWN PERSISTENT NE-SW ORIENTED SFC RIDGE. NO SIGNIFICANT WX ACCOMPANYING FRONT BUT SHRT WV AND LINGERING CONVERGENCE WILL KEEP THREAT OF ISOLD SHOWERS OVER SRN COASTAL SECTIONS DURING EVENING...THUS ADDED 20 POPS THERE. MOS BLEND SUPPORTS PREVIOUS FCST MIN TEMPS...LOWER 60S INLAND TO LOWER 70S COAST. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 400 AM FRI...MODEL GUIDANCE REMAINS IN FAIRLY CLOSE AGREEMENT ON MAJOR SYNOPTIC FEATURES THROUGH THE LONG TERM PERIOD. THROUGH 84 HOURS GENERALLY FOLLOWED A BLEND OF NAM/GFS/SREF...THEN TRANSITIONING TO A BLEND OF 00Z GFS AND 12Z ECMWF. LOOKING AT LATEST 00Z ECMWF IT REMAINS VERY SIMILAR TO THE 00Z GFS. DID NOT MAKE ANY SIGNIFICANT CHANGES TO THE FORECAST THIS PERIOD. BASED ON GFS AND NAM GUIDANCE DID INTRODUCE A SLIGHT CHANCE OF POPS SATURDAY AFTERNOON AND EVENING ASSOCIATED WITH A WEAK BOUNDARY PASSING THROUGH THE AREA. A SURFACE RIDGE WILL PASS TO THE NORTH SUNDAY...THEN OFF THE MID ATLANTIC COAST MONDAY. SOUTHERLY FLOW WILL SET UP MONDAY AHEAD OF THE NEXT COLD FRONT APPROACHING THE AREA. POPS WILL BEGIN INCREASING ON MONDAY...REACHING AROUND 50 PERCENT BY TUESDAY...GRADUALLY DIMINISHING AS THE COLD FRONT MOVES THROUGH ON WEDNESDAY. IF FRONT PUSHES COMPLETELY THROUGH WEDNESDAY IT SHOULD BE DRY WITH CLEARING. FORECAST CONTINUED TO CARRY SMALL POPS AND SOME CLOUDS ALLOWING FOR POSSIBILITY OF FRONT SLOWING AND HANGING ALONG THE COAST A BIT. EXPECT DRY CONDITIONS FOR THURSDAY WITH HIGH PRESSURE BUILDING IN BEHIND THE FRONT. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... SHORT TERM /THROUGH 12Z SATURDAY/... AS OF 700 AM FRIDAY...VFR EXPECTED TO PREVAIL INTO EVENING...THEN GDNC INDICATING SUB-VFR CONDITIONS OVERNIGHT. SCT- BKN SCU/AC HAS PRECLUDED FOG/STRATUS DEVELOPMENT THIS MORNING...WITH SCT SHOWERS CONTINUING TO PUSH IN ALONG COAST WITH ONSHORE FLOW. SHOWERS WILL APPROACH TAF SITES DURING THE DAY AND WILL COVER WITH VCSH IN TAFS. GDNC INDICATES PERIOD OF IFR CIGS/VSBYS ALL SITES LATE TONIGHT...BUT HAS BEEN OVERDONE PAST FEW NIGHTS AND NOT ENOUGH CONFIDENCE TO GO BELOW MVFR AT THIS TIME. LONG TERM /TONIGHT THROUGH TUESDAY/... AS OF 400 AM FRI...PREDOMINANT VFR/DRY CONDITIONS EXPECTED THROUGH THE WEEKEND EXCEPT FOR AN ISOLATED SHOWER/TSTM SATURDAY AFTERNOON/EVENING SOUTHERN AREAS. SEVERAL SURFACE FEATURES WILL BRING A CHANCE FOR SCATTERED CONVECTION MONDAY INTO WEDNESDAY...WITH THE BEST CHANCE TUESDAY INTO TUESDAY NIGHT. PRECIP WILL BE MOSTLY JUST SHOWERS THOUGH CAN`T RULE OUT THUNDER AT TIMES. MOST OF THE ACTIVITY WILL BRING MVFR CONDITIONS...HOWEVER CANNOT RULE OUT SOME PERIODS OF IFR ESPECIALLY TUESDAY INTO TUESDAY NIGHT. && .MARINE... SHORT TERM /THROUGH TONIGHT/... AS OF 935 AM FRIDAY...BASED ON CURRENT OBSERVATIONS HAVE TWEAKED WIND DIRECTIONS TO MORE NE WITH SPEEDS AT 10 TO 15 KNOTS PER LATEST BUOY OBSERVATIONS. SEAS CONTINUE IN THE 2 TO 4 FOOT RANGE WITH A GENERAL 6 TO 7 SECOND SWELL COMPONENT. THESE CONDITIONS SHOULD PREVAIL THROUGH THE AFTERNOON. LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 400 AM FRI...MAINLY LIGHT TO MODERATE NORTH TO NORTHEAST WINDS FOR SATURDAY WILL DIMINISH AND BECOME MORE EASTERLY BY LATE SUNDAY. AS A SURFACE RIDGE PASSES BY TO THE NORTH. SEAS WILL INCREASE TO SMALL CRAFT HOWEVER BEGINNING SATURDAY EVENING...DUE TO SWELLS FROM TROPICAL CYCLONE NADINE. THESE SWELLS WILL DIMINISH BY SUNDAY EVENING...BUT WILL RESULT IN AN HIGH THREAT OF RIP CURRENTS THROUGH THE WEEKEND. THE HIGH WILL MOVE EAST OF THE MID ATLANTIC COAST MONDAY...WITH THE RESULTING FLOW VEERING TO SOUTH AND CONTINUING INTO TUESDAY. THE SOUTHERLY FLOW WILL INCREASE MONDAY NIGHT AND TUESDAY WITH SEAS BUILDING AGAIN TO SMALL CRAFT. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...BEACH HAZARDS STATEMENT UNTIL 8 PM EDT THIS EVENING FOR NCZ095- 103-104. MARINE...NONE. && $$ SYNOPSIS...RSB NEAR TERM...CTC SHORT TERM...RSB LONG TERM...RSB AVIATION...RSB/JBM MARINE...RSB/CTC
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
907 PM CDT SAT SEP 15 2012 .DISCUSSION... VERY LITTLE CHANGE NEEDED...OTHER THAN MAYBE DROPPING LOWS A FEW DEGRESS OVERNIGHT ESP OVER ERN ND. HRRR MODEL DID WELL IN SHOWING WK SFC LOW FORMING IN EAST CENTRAL NORTH DAKOTA SOUTH OF GRAND FORKS EARLY THIS EVENING. SFC LOW IS MOVING TOWARD FOSSTON AND WILL CONTINUE TO MOVE EAST THIS EVENING. WINDS TURNING NORTH AND NORTHWEST BEHIND SFC LOW. SATELLITE SHOWS SCT-BKN HIGH CLOUDS IN PLACE. STILL LOW DEW PTS UPSTREAM IN THE 30S TO AROUND 40 AND WINDS DIMINISHING TO AROUND 5 KTS SHOULD MEAN DECENT RADITIONAL COOLING TONIGHT INTO THE 40S OVER MUCH OF ERN ND WITH SOME LOWER 50S IN WCNTRL MN. && .PREV DISCUSSION... /ISSUED 246 PM CDT SAT SEP 15 2012/ SHORT TERM... THE MAIN ISSUE FOR THE SHORT TERM IS PRECIP TOMORROW ALONG WITH TEMPERATURES THROUGHOUT THE PERIOD. WV LOOP AND UPPER AIR ANALYSIS HAVE MOSTLY ZONAL FLOW OVER THE CWA WITH MOST OF THE SHORTWAVE ACTIVITY STILL TO OUR NORTH OVER CANADA. ONE OF THOSE UPPER TROUGHS WILL BEGIN TO STRENGTHEN AS RIDGING BUILDS OVER BC AND THE TROUGH DIGS INTO CENTRAL CANADA TONIGHT. THIS WILL HELP PUSH THE SFC TROUGH AXIS...CURRENTLY OVER CENTRAL ND...THROUGH THE CWA. WINDS WILL SHIFT TO THE NORTH ON THE BACKSIDE OF THE TROUGH...BUT CURRENT TEMPS BEHIND THE TROUGH AXIS ARE STILL IN THE 70S AND 80S...AND MOST OF THE MODELS SHOW THE BEST COLD AIR ADVECTION LAGGING THE WIND SHIFT BY QUITE A BIT. THE SPC VERSION OF THE WRF BREAKS OUT SOME PRECIP IN NW MN ALONG THE TROUGH AXIS LATER TONIGHT. HOWEVER...WITH CURRENT DEW POINTS IN THE 30S AND 40S AND THAT MODEL BEING AN OUTLIER...WITH KEEP POPS DRY OVERNIGHT. LOWS SHOULD STAY IN THE 40S TO LOW 50S WITH DECENT WINDS KEEPING US MIXED. THE UPPER TROUGH WILL DIG FURTHER INTO THE NORTHERN PLAINS TOMORROW. MODELS ARE IN AGREEMENT WITH KEEPING MOST OF THE PRECIP WELL BEHIND THE SFC FRONT...IN BETTER AGREEMENT WITH THE BEST MID LEVEL FRONTOGENESIS. THERE ARE DIFFERENCE BETWEEN THE MODELS AT EXACTLY WHERE AND WHEN THE PRECIP BANDS SET UP...WITH THE GFS SHOWING SOME ACTIVITY FURTHER NORTH WHILE THE NAM IS MOSTLY OVER OUR SOUTHERN CWA. MADE ONLY MINOR TWEAKS TO POPS DURING THE DAY ON SUNDAY...KEEPING ONLY A SLIGHT CHANCE IN THE NORTHWEST DURING THE MORNING AND THEN SPREADING SOUTH AND EASTWARD BY AFTERNOON. MODEL QPF INCREASES BY SUNDAY NIGHT AS THE FORCING FROM THE MAIN UPPER TROUGH CATCHES UP WITH THE SFC FRONT. THERE IS DECENT AGREEMENT ON THE PLACING OF THE BEST QPF FROM CENTRAL MN INTO THE ARROWHEAD...BUT SOME OF OUR SOUTHEASTERN COUNTIES COULD GET A BETTER SHOT OF RAIN SO INCREASE POPS IN THAT AREA OVERNIGHT. TEMPS WILL BE TRICKY AS COLD AIR ADVECTION WILL BE ONGOING FOR MUCH OF THE DAY. KEPT HIGHS IN THE UPPER 50S IN THE NORTHWEST WITH LOW 70S IN THE SOUTHEAST. LOWS SUNDAY NIGHT SHOULD GET RATHER CHILLY WITH CONTINUED COLD AIR ADVECTION EVEN WITH DECENT NORTH WINDS. KEPT OVERNIGHT READINGS IN THE UPPER 30S TO LOW 40S. THE UPPER TROUGH WILL MOVE OFF TO THE EAST BY MONDAY...ALTHOUGH THERE WILL BE SOME FAIRLY COLD 500MB TEMPS HANGING AROUND OUR NORTHEASTERN COUNTIES FOR THE DAY. WITH THE COLD AIR ALOFT CANNOT COMPLETELY RULE OUT A FEW SHOWERS MONDAY AFTERNOON SO KEPT 20 POPS GOING AROUND LAKE OF THE WOODS...ALTHOUGH LIMITED EXTENT. THE MAIN STORY FOR THE EARLY PART OF THE WORK WEEK WILL BE COOL TEMPS AS 850MB TEMPS DROPPING BELOW ZERO FOR PORTIONS OF THE CWA FOR THE FIRST TIME THIS FALL ON MONDAY. HIGHS SHOULD STAY MAINLY IN THE 50S. THE MAIN SFC HIGH WILL BE TO OUR SOUTHEAST BY MONDAY NIGHT...BUT THINK THERE WILL BE ENOUGH CLEAR SKIES AND LIGHT WINDS TO ALLOW TEMPS TO DROP SIGNIFICANTLY. WENT WITH LOWS IN THE LOW TO MID 30S FOR NOW...BUT IT IS NOT OUT OF THE QUESTION THAT SOME LOCATIONS COULD SEE 20S AND A HARD FREEZE. TEMPS SHOULD RECOVER FOR TUESDAY AFTERNOON AS SOUTH WINDS PICK UP AHEAD OF THE NEXT TROUGH...WITH READINGS MAINLY IN THE 60S. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY GFS/ECMWF IN GOOD AGREEMENT FOR THE LATTER HALF OF NEXT WEEK...BOTH SHOWING STRONG NORTH-NORTHWEST FLOW ALOFT IN HIGHLY AMPLIFIED SYNOPTIC PATTERN. TWO SHORT-WAVES MOVE ACROSS THE NORTHERN PLAINS... THE FIRST TUESDAY NIGHT INTO WEDNESDAY AND THE SECOND THURSDAY INTO FRIDAY. FOR NOW...WILL KEEP 20 TO 30 POPS FOR EACH WAVE AND ATTENDANT COLD FRONT. INSTABILITY IS NEGLIGIBLE...SO NO NEED TO ADD THUNDER AT THIS TIME. MID-LEVEL TEMPERATURES WILL BE CONSISTENTLY IN THE SINGLE DIGITS ABOVE ZERO AFTER EACH WAVE...SO EXPECT A MORE FALL-LIKE WEEK WITH HIGH TEMPERATURES IN THE 50S AND 60S AND LOWS IN THE UPPER 30S TO LOWER 40S. AVIATION... ANY CEILINGS THE NEXT 24 HOURS WILL REMAIN AT OR ABOVE 12000 FT AGL. SOUTH-SOUTHEAST WIND THIS AFTERNOON WITH OCCASIONAL GUSTS UP TO 20 KTS WILL SHIFT TO THE NORTH-NORTHWEST THIS EVENING AS A SURFACE TROUGH/COLD FRONT MOVES ACROSS THE REGION. SOME ISOLATED SHOWERS ARE POSSIBLE SUNDAY MORNING AT KDVL AND KGFK BUT COVERAGE AND TIMING UNCERTAINTY PRECLUDES MENTION IN 18 UTC TAF ISSUANCE. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ RIDDLE/JR
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
153 PM EDT FRI SEP 14 2012 .SYNOPSIS... A COLD FRONT WILL PUSH SOUTHEAST ACROSS THE REGION TODAY. HIGH PRESSURE WILL BUILD SOUTH INTO THE LOWER GREAT LAKES AND OHIO VALLEY TONIGHT. THE HIGH WILL REMAIN ACROSS THE AREA THROUGH THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... PCPN IS CONTINUING TO PROGRESS EAST ACROSS NORTHWEST PORTIONS OF OUR FA. THERE DOES APPEAR TO BE SOME WEAKENING OF THE PCPN IN THE PAST FEW RADAR IMAGES...BUT THE LATEST HRRR IS SILL TRYING TO PUSH PCPN ACROSS OUR ENTIRE FA. WILL NOT GO QUITE AS AGGRESSIVE AS THE HRRR WOULD SUGGEST BUT WILL STILL BUMP UP POPS A BIT MORE ACROSS THE NORTH. SOME UNCERTAINTY EXISTS AS TO HOW MUCH CLEARING WILL MAKE IT INTO OUR NORTHWEST LATER THIS AFTERNOON. HOWEVER...WITH CLOUDS THROUGH AT LEAST A GOOD PORTION OF THE AFTERNOON AND A DEVELOPING CAA PATTERN...WILL DROP HIGHS DOWN INTO THE MID TO UPPER 60S THERE. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... SURFACE HIGH PRESSURE WILL BUILD SOUTH INTO THE GREAT LAKES AND OHIO VALLEY TONIGHT. SKIES WILL CLEAR FROM THE NORTH AS DRIER...COOLER AIR SETTLES INTO THE REGION. RADIATIONAL COOLING WILL BE IN FULL FORCE AND EXPECT OVERNIGHT LOWS TO RANGE FROM THE LOWER 40S NW...AND IN SOME OF THE COLDER SPOTS OF CENTRAL OHIO...TO THE LOWER 50S SOUTH. UNDER A WNW FLOW PATTERN ALOFT...SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH SUNDAY. A FEW CUMULUS CLOUDS MIXED WITH CIRRUS CAN BE EXPECTED DURING THE DAYTIME WITH MAINLY CLEAR SKIES AT NIGHT. HIGHS WILL RANGE FROM THE LOWER TO MID 70S ON SATURDAY...MODERATING SLIGHTLY INTO THE MID AND UPPER 70S ON SUNDAY. RADIATIONAL COOLING WILL OCCUR ONCE AGAIN SATURDAY NIGHT WITH LOWS RANGING FROM THE LOWER 40S TO THE LOWER 50S. MODELS ARE COMING INTO BETTER AGREEMENT IN TERMS OF THE NEXT WEATHER SYSTEMS TO AFFECT THE REGION INTO THE FIRST PART OF THE WEEK. HAVE TAKEN A BLEND OF THE ECMWF AND THE GFS WHICH INDICATE THAT A LONG WAVE TROUGH WILL DIG SOUTH INTO THE GREAT LAKES AND OHIO VALLEY. MEANWHILE...UPR LVL ENERGY NEAR THE DESERT SW WILL EJECT NE INTO TOWARD THE TN AND OHIO VALLEYS. IT IS STILL UNCLEAR ON HOW MUCH MOISTURE WILL BE PULLED NORTHWARD INTO THE REGION FROM THIS SYSTEM AS THE LONG WAVE TROUGH DIGS SOUTHEAST. HAVE RAISED POPS FOR ALL LOCATIONS FOR MONDAY INTO MONDAY NIGHT...BUT THIS VERY WELL COULD GO LIKELY...ESPECIALLY FOR THE SE HALF OF THE AREA. GIVEN CLOUDS AND CHANCES FOR PCPN...HAVE LOWER HIGHS ON TUESDAY INTO THE LOWER AND MID 70S. && .LONG TERM /TUESDAY THROUGH THURSDAY/... AS THE LONG WAVE TROUGH DIGS SOUTHEAST INTO THE REGION ON TUESDAY...A COLD FRONT WILL PUSH SOUTHEAST THROUGH THE AREA. THIS FRONT WILL PROVIDE FOR ANOTHER FOCUS OF SHOWERS. THE FRONT WILL PUSH EAST OF THE REGION TUESDAY NIGHT INTO WEDNESDAY...ALLOWING HIGH PRESSURE OF CANADIAN ORIGIN TO SET UP OVER THE OHIO VALLEY ON WEDNESDAY. DAYTIME HIGHS WILL COOL INTO THE 60S BY WEDNESDAY...WHICH WILL BE SOME 10 TO 15 DEGREES BELOW NORMAL FOR MID SEPTEMBER. HIGH PRESSURE WILL THEN MOVE EAST OF THE AREA ON THURSDAY AS A WEAK UPPER LEVEL DISTURBANCE PUSHES ACROSS THE GREAT LAKES. HAVE GONE WITH A SLIGHT CHANCE OF SHOWERS WITH THIS SYSTEM. TEMPERATURES WILL MODERATE INTO THE LOWER AND MID 70S. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... COLD FRONT IS NOW JUST SOUTHEAST OF THE I-71 CORRIDOR AND HAS PUSHED THROUGH ALL OF THE TAF SITES. THE POST FRONTAL PCPN HAS BEEN GRADUALLY TAPERING OFF AND THIS TREND SHOULD CONTINUE THROUGH THE REMAINDER OF THE AFTERNOON. THIS MAY STILL RESULT IN A FEW RAIN SHOWERS OR SPRINKLES...ESPECIALLY AT KCMH AND KLCK...BUT OVERALL THE PCPN THREAT SHOULD BE DECREASING. MEANWHILE...LOWER MVFR CIGS ARE WORKING IN BEHIND THE FRONT. MODELS ARE INDICATING THAT THESE WILL SLOWLY LIFT AS THEY PUSH EAST THROUGH THE REST OF THE AFTERNOON...BUT WE WILL LIKELY STILL SEE A COUPLE HOUR PERIOD OF MVFR CIGS. OTHERWISE...DRIER AIR WILL MOVE IN OVERNIGHT...ALLOWING FOR SKIES TO BECOME MOSTLY CLEAR THIS EVENING. DESPITE THE CLEARING SKIES AND DECREASING WINDS...THINK DRIER AIR WILL HELP LIMIT THE BR AT KLUK LATER TONIGHT. .OUTLOOK...MVFR CEILINGS ARE POSSIBLE ON MONDAY NIGHT AND TUESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HICKMAN NEAR TERM...JGL SHORT TERM...HICKMAN LONG TERM...NOVAK AVIATION...JGL
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1037 AM EDT FRI SEP 14 2012 .SYNOPSIS... A COLD FRONT WILL PUSH SOUTHEAST ACROSS THE REGION TODAY. HIGH PRESSURE WILL BUILD SOUTH INTO THE LOWER GREAT LAKES AND OHIO VALLEY TONIGHT. THE HIGH WILL REMAIN ACROSS THE AREA THROUGH THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... PCPN IS CONTINUING TO PROGRESS EAST ACROSS NORTHWEST PORTIONS OF OUR FA. THERE DOES APPEAR TO BE SOME WEAKENING OF THE PCPN IN THE PAST FEW RADAR IMAGES...BUT THE LATEST HRRR IS SILL TRYING TO PUSH PCPN ACROSS OUR ENTIRE FA. WILL NOT GO QUITE AS AGGRESSIVE AS THE HRRR WOULD SUGGEST BUT WILL STILL BUMP UP POPS A BIT MORE ACROSS THE NORTH. SOME UNCERTAINTY EXISTS AS TO HOW MUCH CLEARING WILL MAKE IT INTO OUR NORTHWEST LATER THIS AFTERNOON. HOWEVER...WITH CLOUDS THROUGH AT LEAST A GOOD PORTION OF THE AFTERNOON AND A DEVELOPING CAA PATTERN...WILL DROP HIGHS DOWN INTO THE MID TO UPPER 60S THERE. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... SURFACE HIGH PRESSURE WILL BUILD SOUTH INTO THE GREAT LAKES AND OHIO VALLEY TONIGHT. SKIES WILL CLEAR FROM THE NORTH AS DRIER...COOLER AIR SETTLES INTO THE REGION. RADIATIONAL COOLING WILL BE IN FULL FORCE AND EXPECT OVERNIGHT LOWS TO RANGE FROM THE LOWER 40S NW...AND IN SOME OF THE COLDER SPOTS OF CENTRAL OHIO...TO THE LOWER 50S SOUTH. UNDER A WNW FLOW PATTERN ALOFT...SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH SUNDAY. A FEW CUMULUS CLOUDS MIXED WITH CIRRUS CAN BE EXPECTED DURING THE DAYTIME WITH MAINLY CLEAR SKIES AT NIGHT. HIGHS WILL RANGE FROM THE LOWER TO MID 70S ON SATURDAY...MODERATING SLIGHTLY INTO THE MID AND UPPER 70S ON SUNDAY. RADIATIONAL COOLING WILL OCCUR ONCE AGAIN SATURDAY NIGHT WITH LOWS RANGING FROM THE LOWER 40S TO THE LOWER 50S. MODELS ARE COMING INTO BETTER AGREEMENT IN TERMS OF THE NEXT WEATHER SYSTEMS TO AFFECT THE REGION INTO THE FIRST PART OF THE WEEK. HAVE TAKEN A BLEND OF THE ECMWF AND THE GFS WHICH INDICATE THAT A LONG WAVE TROUGH WILL DIG SOUTH INTO THE GREAT LAKES AND OHIO VALLEY. MEANWHILE...UPR LVL ENERGY NEAR THE DESERT SW WILL EJECT NE INTO TOWARD THE TN AND OHIO VALLEYS. IT IS STILL UNCLEAR ON HOW MUCH MOISTURE WILL BE PULLED NORTHWARD INTO THE REGION FROM THIS SYSTEM AS THE LONG WAVE TROUGH DIGS SOUTHEAST. HAVE RAISED POPS FOR ALL LOCATIONS FOR MONDAY INTO MONDAY NIGHT...BUT THIS VERY WELL COULD GO LIKELY...ESPECIALLY FOR THE SE HALF OF THE AREA. GIVEN CLOUDS AND CHANCES FOR PCPN...HAVE LOWER HIGHS ON TUESDAY INTO THE LOWER AND MID 70S. && .LONG TERM /TUESDAY THROUGH THURSDAY/... AS THE LONG WAVE TROUGH DIGS SOUTHEAST INTO THE REGION ON TUESDAY...A COLD FRONT WILL PUSH SOUTHEAST THROUGH THE AREA. THIS FRONT WILL PROVIDE FOR ANOTHER FOCUS OF SHOWERS. THE FRONT WILL PUSH EAST OF THE REGION TUESDAY NIGHT INTO WEDNESDAY...ALLOWING HIGH PRESSURE OF CANADIAN ORIGIN TO SET UP OVER THE OHIO VALLEY ON WEDNESDAY. DAYTIME HIGHS WILL COOL INTO THE 60S BY WEDNESDAY...WHICH WILL BE SOME 10 TO 15 DEGREES BELOW NORMAL FOR MID SEPTEMBER. HIGH PRESSURE WILL THEN MOVE EAST OF THE AREA ON THURSDAY AS A WEAK UPPER LEVEL DISTURBANCE PUSHES ACROSS THE GREAT LAKES. HAVE GONE WITH A SLIGHT CHANCE OF SHOWERS WITH THIS SYSTEM. TEMPERATURES WILL MODERATE INTO THE LOWER AND MID 70S. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... PRIMARY CONCERN FOR THE TAFS IS THE COLD FRONTAL PASSAGE EXPECTED TO OCCUR THIS MORNING...WITH POTENTIAL FOR PRECIPITATION AND LOW CEILINGS INTO THE AFTERNOON. THE FRONT WILL BE MOVING SOUTHEAST THROUGH THE TAF SITES THIS MORNING...WITH WINDS SHIFTING TO NNW AND EVENTUALLY BECOMING SLIGHTLY GUSTY (UP TO 20 KNOTS). ALONG WITH THE WIND SHIFT...MOISTURE WILL BE INCREASING NEAR AND BEHIND THE FRONT. THIS SET OF TAFS IS SLIGHTLY MORE PESSIMISTIC THAN THE LAST SET...WITH MVFR CEILINGS NOW APPEARING LIKELY FOR THE NORTHERN TAF SITES. THERE ARE SOME IFR CEILINGS THAT HAVE DEVELOPED OVER INDIANA...WHICH COULD POSSIBLY MOVE INTO KDAY THIS MORNING. HOWEVER...MULTIPLE MODEL SOURCES ARE INDICATING THAT THESE VERY LOW CEILINGS WILL LIFT SLIGHTLY BEFORE THE MOISTURE MAKES IT INTO THE REGION. PRECIPITATION IS NOT GOING TO BE A MAJOR CONCERN...AS THERE IS NOT MUCH MOISTURE FOR THE FRONT TO WORK WITH. VCSH WILL BEST HANDLE THE THREAT AT THIS TIME...WITH THE PRECIPITATION NOT EXPECTED TO HIT EVERY LOCATION...AND NOT EXPECTED TO BE A SIGNIFICANT CONCERN WITH REGARDS TO FLIGHT CATEGORIES. A TEMPO FOR LIGHT SHOWERS HAS BEEN INCLUDED AT KDAY...WHERE PASSING SHOWERS WILL BE MORE LIKELY. NORTHERLY WINDS WILL BECOME LIGHT TONIGHT...WITH CLEARING SKIES AND GENERALLY VFR CONDITIONS. THE SIGNIFICANT COOLING COULD LEAD TO FOG IN VALLEY LOCATIONS (SUCH AS KLUK). .OUTLOOK...MVFR CEILINGS ARE POSSIBLE ON MONDAY NIGHT AND TUESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HICKMAN NEAR TERM...JGL SHORT TERM...HICKMAN LONG TERM...NOVAK AVIATION...HATZOS
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1038 PM CDT SAT SEP 15 2012 .DISCUSSION.../ISSUED AT 1002 PM CDT/ FORECAST LOOKS MAINLY ON TRACK FOR TONIGHT. MADE SOME MINOR ADJUSTMENTS UPWARD IN SOME OF THE LOW TEMPERATURES...AS STRONG 925MB WINDS SHOULD KEEP A SOUTHERLY BREEZE UP AT THE SURFACE MUCH OF THE NIGHT. PARTS OF SOUTHWEST MINNESOTA ALONG AND JUST DOWNWIND OF THE BUFFALO RIDGE SHOULD SEE GUSTS AROUND 25 MPH THROUGH THE NIGHT. THE SOUTHERLY WINDS WILL BRING AN INCREASE IN LOW LEVEL MOISTURE ACROSS THE EASTERN HALF OF THE CWA LATER TONIGHT...WITH DEWPOINTS RISING INTO THE MID 50S. NAM AND HRRR HINTING THAT SOME LOW STRATUS OR FOG COULD FORM ACROSS NORTHWEST IOWA AS THIS MOISTURE INCREASES LATER TONIGHT INTO TOMORROW MORNING. TEND TO THINK STRATUS IS MORE PROBABLE GIVEN THAT WINDS SHOULD STAY UP...SO INCREASED CLOUD COVER SOME IN NORTHWEST IOWA. /CHENARD && .AVIATION.../FOR THE 06Z TAF ISSUANCE/ VFR CONDITIONS GNERALLY EXPECTED THROUGH 06Z MONDAY. COLD FRONT WILL SAG SLOWLY SOUTH THROUGH 06Z REACHING I90 BY 00Z AND THROUGH NORTHWEST IOWA BY 06Z. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP NORTH OF THIS FRONT AFTER 03Z MONDAY. PATCHY FOG AND STRATUS MAY DEVELOP OVER PORTIONS OF NORTHWEST IOWA 09Z-13Z. && .PREVIOUS DISCUSSION.../ISSUED AT 226 PM CDT/ UNEVENTFUL NIGHT IN STORE ACROSS THE AREA AS HIGH PRESSURE CONTINUES TO PUSH OFF TO THE SOUTHEAST AS A SURFACE TROUGH APPROACHES FROM THE WEST. GUSTY SOUTHWESTERLY WINDS WILL DROP OFF EARLY THIS EVENING WITH LOSS OF MIXING...THOUGH REMAIN IN THE 7 TO 10 KT RANGE OVER MOST OF THE AREA OVERNIGHT WITH A DECENT GRADIENT ACROSS THE AREA. THE EXCEPTION WILL BE OVER THE FAR NORTHWEST WHERE WINDS WILL DROP OFF IN THE VICINITY OF THE SURFACE TROUGH AXIS. THERE LOOKS TO BE THE POSSIBILITY OF PATCHY FOG ACROSS THE SOUTHEASTERN PORTIONS OF THE CWA LATE TONIGHT WITH DECENT LOW LEVEL MOISTURE TRANSPORT...RESULTING IN RISING DEWPOINTS INTO THE MID 50S OVER THAT AREA BY VERY EARLY SUNDAY MORNING. LOWS TONIGHT WILL GENERALLY BE MILDER THAN SATURDAY MORNING WITH READINGS ONLY DROPPING INTO THE LOWER TO MID 50S. THE SURFACE TROUGH/FRONTAL BOUNDARY BEGINS TO PUSH FROM NORTHWEST TO SOUTHEAST ACROSS THE AREA ON SUNDAY...BISECTING OUR CWA BY LATE SUNDAY AFTERNOON. THINK THAT ANY PRECIPITATION WITH THE SYSTEM WILL HOLD OFF DURING THE DAY WITH DRY AIR IN THE LOW/MID LEVELS AND LITTLE IN THE WAY OF UPPER LEVEL SUPPORT. HIGHS WILL AGAIN BE IN THE 80S...WITH WARMEST READINGS THROUGH THE MISSOURI RIVER CORRIDOR. FOR SUNDAY NIGHT...REALLY NO CHANGE IN STRENGTH OR TIMING FOR THE NEXT SHORT WAVE IMPACTING OUR AREA. BOTH THE NAM AND GFS SHOW THE STRONGEST PORTION OF THE WAVE AFFECTING OUR SOUTHWEST MN ZONES AS THE CRUX OF THE UPPER WAVE MOVES THROUGH CENTRAL/NORTHERN MN. HUMIDITY TIME SECTIONS CONTINUE TO ALSO SHOW A STRIPE OF DECENT MOISTURE SUNDAY NIGHT...ESPECIALLY FOR OUR NORTHERN AND EASTERN ZONES. DECIDED TO RAISE OUR ALREADY HIGH POPS TO A LOW END CATEGORICAL FOR MANY OF OUR NORTHERN ZONES...AS THINKING THAT MEASURABLE RAINFALL IS GETTING ALMOST CERTAIN IN THOSE AREAS. POPS THEN SLOWLY DECREASE TO THE SOUTH OF THOSE ZONES. NO CHANGES NEEDED TO LOWS. MONDAY WILL LIKELY HAVE ELEVATED FIRE DANGER ONCE AGAIN. BUT AT THIS TIME...IT APPEARS THE MINIMUM HUMIDITY VALUES WILL BE A LITTLE TOO HIGH...AND WINDS A SMIDGE TOO LOW FOR RED FLAG WARNING CONDITIONS. THEREFORE OPTED TO ISSUE NO FIRE WEATHER WATCH AT THIS TIME. DECENT MIXING SHOULD GIVE HIGHS IN THE UPPER 50S TO MID 60S. LATE MONDAY NIGHT AND VERY EARLY TUESDAY...DECIDED TO ADD IN SOME PATCHY FROST WHEREVER THE HOURLY TEMPERATURES DIPPED AT OR JUST BELOW 36 DEGREES. WITH CLEAR SKIES AND LIGHT WINDS ANTICIPATED...MORNING LOWS WILL BE QUITE CHILLY FOR THIS TIME OF YEAR. OTHERWISE THE REST OF THE FORECAST WILL FEATURE A HIGH AMPLITUDE FLOW ACROSS THE EASTERN HALF OF NORTH AMERICA RIGHT INTO NEXT WEEKEND. ONE SHORT WAVE IS WELL ADVERTISED BY BOTH THE GFS AND ECMWF TO MOVE ACROSS MN ON WEDNESDAY...DRAGGING A SURFACE COLD FRONT THROUGH OUR AREA REINFORCING THE CHILLY AIR. THEN THINGS POTENTIALLY REALLY COOL OFF FOR LATE IN THE WEEK. THE ECMWF AND GEM GLOBAL SHOW LONG WAVE TROUGHING CARVING A BIG CHUNK OF REAL ESTATE THROUGH THE MIDDLE PORTION OF THE COUNTRY BY LATE IN THE WEEK. BOTH MODELS SHOW DEEP TROUGHING BACK INTO THE WESTERN PLAINS...WHEREAS THE GFS IS MORE OF A NW FLOW ALOFT AND KEEPING MOST OF THE DEEP TROUGHING OVER THE EASTERN THIRD OF THE UNITED STATES. IF THE GEM GLOBAL AND ECMWF VERIFY...WILL NEED TO COOL OFF TEMPERATURES FURTHER ON FUTURE SHIFTS TO SOME PRETTY CHILLY READINGS...BUT LITTLE CHANCE FOR DECENT MEASURABLE RAINFALL. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...NONE. MN...NONE. NE...NONE. SD...NONE. && $$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1002 PM CDT SAT SEP 15 2012 .DISCUSSION.../ISSUED AT 1002 PM CDT/ FORECAST LOOKS MAINLY ON TRACK FOR TONIGHT. MADE SOME MINOR ADJUSTMENTS UPWARD IN SOME OF THE LOW TEMPERATURES...AS STRONG 925MB WINDS SHOULD KEEP A SOUTHERLY BREEZE UP AT THE SURFACE MUCH OF THE NIGHT. PARTS OF SOUTHWEST MINNESOTA ALONG AND JUST DOWNWIND OF THE BUFFALO RIDGE SHOULD SEE GUSTS AROUND 25 MPH THROUGH THE NIGHT. THE SOUTHERLY WINDS WILL BRING AN INCREASE IN LOW LEVEL MOISTURE ACROSS THE EASTERN HALF OF THE CWA LATER TONIGHT...WITH DEWPOINTS RISING INTO THE MID 50S. NAM AND HRRR HINTING THAT SOME LOW STRATUS OR FOG COULD FORM ACROSS NORTHWEST IOWA AS THIS MOISTURE INCREASES LATER TONIGHT INTO TOMORROW MORNING. TEND TO THINK STRATUS IS MORE PROBABLE GIVEN THAT WINDS SHOULD STAY UP...SO INCREASED CLOUD COVER SOME IN NORTHWEST IOWA. /CHENARD .PREVIOUS DISCUSSION.../ISSUED AT 226 PM CDT/ UNEVENTFUL NIGHT IN STORE ACROSS THE AREA AS HIGH PRESSURE CONTINUES TO PUSH OFF TO THE SOUTHEAST AS A SURFACE TROUGH APPROACHES FROM THE WEST. GUSTY SOUTHWESTERLY WINDS WILL DROP OFF EARLY THIS EVENING WITH LOSS OF MIXING...THOUGH REMAIN IN THE 7 TO 10 KT RANGE OVER MOST OF THE AREA OVERNIGHT WITH A DECENT GRADIENT ACROSS THE AREA. THE EXCEPTION WILL BE OVER THE FAR NORTHWEST WHERE WINDS WILL DROP OFF IN THE VICINITY OF THE SURFACE TROUGH AXIS. THERE LOOKS TO BE THE POSSIBILITY OF PATCHY FOG ACROSS THE SOUTHEASTERN PORTIONS OF THE CWA LATE TONIGHT WITH DECENT LOW LEVEL MOISTURE TRANSPORT...RESULTING IN RISING DEWPOINTS INTO THE MID 50S OVER THAT AREA BY VERY EARLY SUNDAY MORNING. LOWS TONIGHT WILL GENERALLY BE MILDER THAN SATURDAY MORNING WITH READINGS ONLY DROPPING INTO THE LOWER TO MID 50S. THE SURFACE TROUGH/FRONTAL BOUNDARY BEGINS TO PUSH FROM NORTHWEST TO SOUTHEAST ACROSS THE AREA ON SUNDAY...BISECTING OUR CWA BY LATE SUNDAY AFTERNOON. THINK THAT ANY PRECIPITATION WITH THE SYSTEM WILL HOLD OFF DURING THE DAY WITH DRY AIR IN THE LOW/MID LEVELS AND LITTLE IN THE WAY OF UPPER LEVEL SUPPORT. HIGHS WILL AGAIN BE IN THE 80S...WITH WARMEST READINGS THROUGH THE MISSOURI RIVER CORRIDOR. FOR SUNDAY NIGHT...REALLY NO CHANGE IN STRENGTH OR TIMING FOR THE NEXT SHORT WAVE IMPACTING OUR AREA. BOTH THE NAM AND GFS SHOW THE STRONGEST PORTION OF THE WAVE AFFECTING OUR SOUTHWEST MN ZONES AS THE CRUX OF THE UPPER WAVE MOVES THROUGH CENTRAL/NORTHERN MN. HUMIDITY TIME SECTIONS CONTINUE TO ALSO SHOW A STRIPE OF DECENT MOISTURE SUNDAY NIGHT...ESPECIALLY FOR OUR NORTHERN AND EASTERN ZONES. DECIDED TO RAISE OUR ALREADY HIGH POPS TO A LOW END CATEGORICAL FOR MANY OF OUR NORTHERN ZONES...AS THINKING THAT MEASURABLE RAINFALL IS GETTING ALMOST CERTAIN IN THOSE AREAS. POPS THEN SLOWLY DECREASE TO THE SOUTH OF THOSE ZONES. NO CHANGES NEEDED TO LOWS. MONDAY WILL LIKELY HAVE ELEVATED FIRE DANGER ONCE AGAIN. BUT AT THIS TIME...IT APPEARS THE MINIMUM HUMIDITY VALUES WILL BE A LITTLE TOO HIGH...AND WINDS A SMIDGE TOO LOW FOR RED FLAG WARNING CONDITIONS. THEREFORE OPTED TO ISSUE NO FIRE WEATHER WATCH AT THIS TIME. DECENT MIXING SHOULD GIVE HIGHS IN THE UPPER 50S TO MID 60S. LATE MONDAY NIGHT AND VERY EARLY TUESDAY...DECIDED TO ADD IN SOME PATCHY FROST WHEREVER THE HOURLY TEMPERATURES DIPPED AT OR JUST BELOW 36 DEGREES. WITH CLEAR SKIES AND LIGHT WINDS ANTICIPATED...MORNING LOWS WILL BE QUITE CHILLY FOR THIS TIME OF YEAR. OTHERWISE THE REST OF THE FORECAST WILL FEATURE A HIGH AMPLITUDE FLOW ACROSS THE EASTERN HALF OF NORTH AMERICA RIGHT INTO NEXT WEEKEND. ONE SHORT WAVE IS WELL ADVERTISED BY BOTH THE GFS AND ECMWF TO MOVE ACROSS MN ON WEDNESDAY...DRAGGING A SURFACE COLD FRONT THROUGH OUR AREA REINFORCING THE CHILLY AIR. THEN THINGS POTENTIALLY REALLY COOL OFF FOR LATE IN THE WEEK. THE ECMWF AND GEM GLOBAL SHOW LONG WAVE TROUGHING CARVING A BIG CHUNK OF REAL ESTATE THROUGH THE MIDDLE PORTION OF THE COUNTRY BY LATE IN THE WEEK. BOTH MODELS SHOW DEEP TROUGHING BACK INTO THE WESTERN PLAINS...WHEREAS THE GFS IS MORE OF A NW FLOW ALOFT AND KEEPING MOST OF THE DEEP TROUGHING OVER THE EASTERN THIRD OF THE UNITED STATES. IF THE GEM GLOBAL AND ECMWF VERIFY...WILL NEED TO COOL OFF TEMPERATURES FURTHER ON FUTURE SHIFTS TO SOME PRETTY CHILLY READINGS...BUT LITTLE CHANCE FOR DECENT MEASURABLE RAINFALL. && .AVIATION.../FOR THE 00Z TAF ISSUANCE/ VFR CONDITIONS EXPECTED THROUGH 00Z MONDAY. COLD FRONT WILL SAG SLOWLY SOUTH THROUGH 00Z REACHING I90 BY LATE SUNDAY AFTERNOON. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...NONE. MN...RED FLAG WARNING UNTIL 8 PM CDT THIS EVENING FOR MNZ900. NE...NONE. SD...RED FLAG WARNING UNTIL PM CDT THIS EVENING FOR SDZ255>258. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1149 PM CDT THU SEP 13 2012 .SHORT TERM...TONIGHT THROUGH SUNDAY 313 PM CDT THU SEP 13 2012 MAIN FORECAST CONCERNS ARE FOG IN RIVER VALLEYS AND FROST POTENTIAL TONIGHT...THEN TEMPERATURES FRIDAY THROUGH SUNDAY. LATEST WATER VAPOR SATELLITE IMAGERY SHOWS UPPER LEVEL LOW OVER SOUTHERN MANITOBA AND SHORTWAVE TROUGH EMBEDDED IN THE NORTHWESTERLY FLOW OVER CENTRAL NORTH DAKOTA. LATEST 19Z SURFACE ANALYSIS INDICATING HIGH PRESSURE BUILDING INTO WESTERN IOWA AND DRIER AIR BEGINNING TO ADVECT INTO WESTERN FORECAST AREA...WITH DEWPOINTS FALLING INTO THE MIDDLE 20S TO MIDDLE 30S ACROSS SOUTHERN AND WESTERN MINNESOTA. THE 13.12Z GFS/NAM ARE IN DECENT AGREEMENT WITH DEVELOPING ZONAL FLOW ACROSS THE NORTHERN TIER STATES THIS WEEKEND. THE MOST SIGNIFICANT DIFFERENCE BETWEEN THE DETERMINISTIC MODELS IS THE NAM SLIGHTLY FARTHER SOUTH WITH SURFACE FRONT SUNDAY THAN THE GFS. THIS WOULD PUSH THE MOISTURE CONVERGENCE AND LIFT ALONG THE FRONT INTO THE NORTHERN FORECAST AREA. HOWEVER...FEEL THE NAM IS TOO FAR SOUTH AND FOLLOW MORE TOWARDS THE GFS DURING THIS TIMEFRAME. TONIGHT...THE DETERMINISTIC 13.12Z GFS/NAM AND 13.18Z RAP ARE PICKING UP WEAK WARM AIR ADVECTION AT 700MB OUT AHEAD OF THE SHORTWAVE TROUGH OVER CENTRAL NORTH DAKOTA AND PRODUCING MOISTURE IN THE 600-800MB LAYER PER BUFKIT SOUNDINGS. THE MOISTURE IN THIS LAYER THE DETERMINISTIC MODELS PROG INTO THE FORECAST AREA AFTER 03Z FRIDAY AND WILL HAVE IMPACTS ON TEMPERATURES AND FOG POTENTIAL. AT THIS TIME... UNCERTAINTY EXIST ABOUT FOG DEVELOPMENT IN THE MISSISSIPPI RIVER VALLEY...AS THE 13.12Z DETERMINISTIC MODELS ARE IN AGREEMENT SOME MID LEVEL CLOUDS WILL DRIFT OVER THE FORECAST AREA BETWEEN 03Z-09Z TIMEFRAME. FOR NOW...HAVE KEPT PATCHY TO AREAS FOG IN RIVER VALLEYS. TEMPERATURES WILL BE AFFECTED BY THE SCATTERED TO BROKEN MID LEVEL DECK CLOUDS ESPECIALLY OVER SOUTHEAST MINNESOTA AND NORTHEAST IOWA. THE 13.12Z DETERMINISTIC MODELS DISSIPATE MOISTURE/MID CLOUD DECK OVER WESTERN/CENTRAL WISCONSIN AND TEMPERATURES ARE EXPECTED TO FALL INTO THE MIDDLE 30S OVER PARTS OF CENTRAL WISCONSIN AND PRODUCE ISOLATED SPOTS OF PATCHY FROST. SURFACE RIDGE DOMINATES THE FORECAST AREA FRIDAY INTO SATURDAY PROVIDING DRY WEATHER CONDITIONS. TEMPERATURES ARE EXPECTED TO MODERATE AND BE SLIGHTLY ABOVE NORMAL BOTH DAYS...AS THE 13.12Z DETERMINISTIC MODELS ADVECT SOME WARMER AIR INTO THE AREA. SURFACE RIDGE BUILDS INTO THE OHIO RIVER VALLEY SATURDAY NIGHT/SUNDAY AND SOUTHERLY WINDS ON THE BACKSIDE OF THE HIGH PRESSURE SYSTEM AND ALOFT...WILL USHER IN LOW LEVEL MOISTURE FROM THE SOUTHERN PLAINS STATES NORTHWARD INTO THE FORECAST AREA. THIS IS EVIDENT IN THE 850MB TO 925MB RELATIVE HUMIDITY FIELDS PER 13.12Z GFS/NAM. HAVE INCREASE SKY COVER SLIGHTLY SUNDAY. .LONG TERM...SUNDAY NIGHT THROUGH THURSDAY 313 PM CDT THU SEP 13 2012 MAIN FORECAST CONCERNS THROUGH THE PERIOD ARE PRECIPITATION CHANCES AND TEMPERATURES. THE 13.12Z GFS/ECMWF/GEM ARE IN ALL PRETTY GOOD AGREEMENT IN DIGGING UPPER LEVEL TROUGH OVER THE NORTHERN PLAINS AND THE UPPER GREAT LAKES REGION THROUGH FORECAST PERIOD. BIGGEST DIFFERENCE BETWEEN THE DETERMINISTIC MODELS IS TIMING OF THE EMBEDDED SHORTWAVE TROUGHS IN THE NORTHERLY FLOW ALOFT. THIS WILL HAVE IMPACTS ON TIMING OF PRECIPITATION CHANCES INTO THE FORECAST AREA THROUGH THE FORECAST PERIOD. THE DETERMINISTIC 13.12Z GFS/ECMWF/GEM CONTINUE TO SHOW COLDER AIR TO FILTER INTO THE AREA WITH 850MB TEMPERATURES DROPPING TO AROUND ZERO DEGREES CELSIUS AT 12Z TUESDAY. THE 13.00Z GEFS INDICATE STANDARD ANOMALIES OF MINUS 1 TO MINUS 1.5 OVER THE FORECAST AREA MIDDLE OF NEXT WEEK. TEMPERATURES WILL BE BELOW NORMAL THROUGH MUCH OF THE FORECAST PERIOD WITH HIGH TEMPERATURES RISING INTO THE 50S TO 60S. && .AVIATION...THROUGH 06Z SATURDAY 1148 PM CDT THU SEP 13 2012 AN UPPER LEVEL LOW OVER SOUTHWEST ONTARIO HAS A STRONG SHORT WAVE TROUGH MOVING ACROSS NORTHWEST MINNESOTA. A DECK OF MID LEVEL CLOUDS AHEAD OF THE SHORT WAVE TROUGH CONTINUES TO ADVANCE SOUTHEAST TOWARD THE AREA AND WILL OVERSPREAD BOTH TAF SITES SHORTLY AFTER 06Z. USING SATELLITE TO TIME THE BACK EDGE OF THE CLOUDS...EXPECTING THEM TO REMAIN FOR MOST OF THE NIGHT CLEARING OUT AROUND 12Z. THIS WILL BE LONG ENOUGH TO KEEP FOG FROM FORMING AT KLSE AND HAVE REMOVED THIS FROM THE FORECAST. ONCE THE CLOUDS CLEAR OUT...HIGH PRESSURE WILL BUILD IN FOR CLEAR SKIES AND LIGHT WINDS. && .ARX WATCHES/WARNINGS/ADVISORIES... 313 PM CDT THU SEP 13 2012 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM.....DTJ LONG TERM......DTJ AVIATION...04
AREA FORECAST DISCUSSION
NWS DES MOINES IA
330 AM CDT SUN SEP 16 2012 .SHORT TERM /TODAY/... COUPLE OF CHALLENGES FOR TODAYS FORECAST INCLUDE LOW STRATUS MOVING NORTH FROM MISSOURI AND KANSAS IN RIBBON OF LOW LEVEL MOISTURE FROM H925 TO H850 EARLY TODAY. SUBJECTIVE H850 ANALYSIS AT 00Z SUN SHOWED RAPID EXPANSION OF 50 TO 60F DEW POINTS AT THE SFC JUST TO OUR WEST NOSING NORTH INTO EASTERN NEBRASKA WHILE ALOFT 0 TO 10C DEW POINTS RAPIDLY HEADING NORTH AS WELL. WARM AIR ADVECTION IS ALSO EXPECTED TO INCREASE THROUGH THE DAY...ESPECIALLY JUST AHEAD OF SLOW MOVING COLD FRONT WHICH WILL BE NEAR THE IOWA AND MINNESOTA BORDERS BY 00Z. WITH H850 TEMPS INCREASING TO 13C SOUTH TO 16C ALONG THE NORTHERN BORDER...AFTERNOON HIGH TEMPS WILL RISE INTO THE LOWER TO MID 80S NORTH HALF...TEMPERED BY STRATOCU THAT SHOULD TAKE OVER ONCE HEATING COMMENCES THIS MORNING. STILL SOME QUESTIONS EVEN AT THIS HOUR... 07Z SUN...AS TO HOW WIDESPREAD LOW CLOUDS WILL BE BY 12Z...THOUGH THE AREA SOUTH IS DEFINITELY DEVELOPING SLOWLY NORTH. NAM BUFR SOUNDING NEAR CRESTON IN THE SOUTHWEST SUGGESTS CEILINGS MAY BEGIN THE MORNING NEAR 1000 FT WITH ONLY A SLIGHT IMPROVEMENT BY 15Z TO 2 TO 3KFT...EVENTUALLY BECOMING PARTLY CLOUDY BY THE NOON HOUR. WILL MONITOR THROUGH 12Z FOR POSSIBLE UPDATES TO SKY GRIDS ACROSS THE WEST AND SOUTH WHICH MAY NEED HIGHER VALUES. THOUGH SFC DEW POINTS WILL RISE THIS AFTERNOON ALONG WITH HIGH TEMPS...AND MLCAPE WILL RISE TO 600 TO 800 J/KG ALONG OVER THE NORTHWEST HALF TOWARD 00Z... THERE IS LITTLE FORCING AHEAD OF THE BOUNDARY AND A WEAK CAP NEAR H800 SHOULD INHIBIT CONVECTION. THUS...THUNDER CHANCES REMAIN NIL UNTIL LATER THIS EVENING AS FRONT APPROACHES THE NORTHERN BORDER. SOUTHWEST FLOW WILL DEVELOP AHEAD OF THE BOUNDARY TODAY BUT MIXING REMAINS QUITE MEAGER WITH WINDS OF 12 TO 15 MPH THROUGH THE BOUNDARY LAYER AHEAD OF THE BOUNDARY. .LONG TERM /TONIGHT THROUGH SATURDAY/... NO LARGE SCALE CHANGES TO THE EXTENDED WITH THE FORECAST CONCERNS BEING THE PRECIP CHANCES TONIGHT THROUGH MONDAY FOLLOWED BY THE COLD TEMPS AND FROST POTENTIAL. MODELS ARE STILL DEPICTING A SLOWER MOVEMENT TO THE FRONT WITH LIMITED MOISTURE. THERE WILL BE CAPPING AHEAD OF THE FRONT FURTHER LIMITING CONVECTIVE POTENTIAL. EVEN THE FRONTOGENETICAL FORCING WHICH WAS DECENT YESTERDAY IS A LITTLE SLOWER...A LITTLE WEAKER AND FALLS APART AS IT SHIFTS ACROSS IOWA. THERE IS A NARROW AREA OF CAPE...MAINLY RIGHT ALONG AND IMMEDIATELY BEHIND THE FRONT AND THIS WILL BE THE BEST OPPORTUNITY TO SEE THUNDER. I HAVE KEPT THE ISOLATED WORDING AS A RESULT. PRECIP SHOULD BEGIN OVER THE DAKOTAS AND MN THIS EVENING BUT SHOULD STAY OUT OF IA UNTIL AFTER MIDNIGHT. I WAS GENEROUS IN POPS BEFORE 09Z TO STAY IN COLLABORATION BUT SOUNDINGS REALLY DO NOT MOISTEN SUFFICIENTLY UNTIL THE 09Z-12Z PERIOD REACHING A PEAK BETWEEN 15Z-18Z THEN DRYING OUT AGAIN. I BACKED OFF ON QPF JUST A BIT BASED ON THE LACK OF MOISTURE IN THE FORECAST SOUNDINGS. POST FRONTAL WE WILL EXPERIENCE STRONG COLD ADVECTION MONDAY NIGHT AND AS SKIES CLEAR NORTH AND WEST TEMPS OVERNIGHT WILL BE THE COLDEST WE HAVE SEEN YET THIS SEASON. READINGS ESPECIALLY IN LOW LYING AREAS SHOULD DROP INTO THE MID TO UPPER 30S...ENOUGH TO SEE AT LEAST SOME PATCHY FROST. AT THIS POINT IT IS NOT HEADLINE WORTHY BUT THERE WILL BE A MENTION IN THE HWO FOR PEOPLE WHO DO WANT TO THINK ABOUT PROTECTING PLANTS. BENIGN WEATHER UNTIL WEDNESDAY/THURSDAY WHEN A FAIRLY STRONG SHORTWAVE DROPS DOWN IN THE NORTHERLY FLOW OVER THE REGION. THERE IS SOME DISCREPANCY AS TO HOW MUCH THE WAVE WILL DIG AND HOW IT WILL MOVE BUT FOR NOW IT LOOKS LIKE NORTHEAST IOWA WILL GET A GLANCING BLOW FROM THIS FEATURE AND I HAVE RELEGATED POPS WITH THIS FEATURE MAINLY TO THE NORTHEAST AND EAST. REINFORCING COLD AIR WILL THEN PUSH BACK INTO IOWA BUT THERE IS LARGE DISCREPANCIES AS TO HOW COLD NEXT WEEKEND WILL BE AND THE EVOLUTION OF THE UPPER PATTERN. THE EURO WANTS TO DROP ANOTHER STRONG WAVE OVER US AND DEVELOP A CLOSED LOW JUST TO THE EAST. WHEN THE GFS IS MUCH WEAKER WITH THE WAVE AND DOES NOT DEVELOP A CLOSED LOW WITH IT. FOR NOW I KEPT THE WEEKEND DRY BUT THIS THERE WILL OBVIOUSLY BE SOME ADJUSTMENTS WITH TIME. && .AVIATION...16/06Z MVFR STRATUS DECK STILL PROGGED TO MOVE NORTHWARD OVERNIGHT AND MAINLY AFFECT DSM AND FOD BY AROUND 10Z. CLOUD DECK MAY PUSH AS FAR EAST AS OTM...BUT HAD LOW CONFIDENCE WITH ANY MENTION OF MVFR AS LATEST HRRR AND WRF MODELS KEEP DECK TO THE WEST. ENOUGH MIXING SUNDAY AFTERNOON FOR GUSTS IN THE MID-UPPER TEENS. OTHERWISE...INCREASING HIGH CLOUDS TOMORROW NIGHT WITH APPROACHING TROUGH. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...REV LONG TERM...FAB AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1154 PM CDT SAT SEP 15 2012 ...UPDATED AVIATION DISCUSSION... .SHORT TERM /TONIGHT/... HIGH PRESSURE CENTERED OVER NORTHEAST MO WILL CONTINUE EAST WITH RETURN FLOW OF MORE MOIST AIR COMING AROUND THE BACK SIDE. THEREIN LIES THE PROBLEM FOR TONIGHT. HOW FAR TO BRING THE CLOUDS INTO SOUTHWEST IA AND THEN EVENTUALLY SPREADING THEM NORTHEAST. THE NAM/WRF AND EXPERIMENTAL SATELLITE PRODUCTS SEEM TO HAVE A PRETTY GOOD HANDLE ON IT AND WILL BRING CLOUDS TO JUST WEST OF OTTUMWA...THROUGH ABOUT AMES...TO FORT DODGE...THEN BACK TO DENISON. LOW TEMPS SUN SHOULD BE 5 TO 10 DEG WARMER THAN THIS MORNING. .LONG TERM /SUNDAY THROUGH SATURDAY/... THE COOLEST TEMPERATURES THUS FAR THIS SEASON WILL AFFECT OUR REGION BY THE MIDDLE OF THIS COMING WEEK...BUT NOT BEFORE A CHANCE OF RAINFALL SUNDAY NIGHT INTO MONDAY. SUNDAY IS A CHALLENGING DAY TO FORECAST...GIVEN THAT WE WILL BE IN THE TRANSITION ZONE BETWEEN A DEPARTING SFC HIGH AND THE APPROACHING NEXT WX SYSTEM. A LONG WAVE TROF WILL BRING THE NEXT WX SYSTEM TO OUR REGION...WITH BEST CHANCES OF PRECIP LATE SUNDAY NIGHT INTO MONDAY. MODELS HAVE BEEN TRENDING SLIGHTLY SLOWER WITH THIS SYSTEM. ALTHOUGH THE BEST FRONTOGENETICAL FORCING REMAINS NORTH OF IA-MN BORDER...PRECIP IS STILL EXPECTED IN OUR CWA. IN TERMS OF CONVECTION...ONLY ISOLATED TSRA ARE EXPECTED AT BEST. STRONG CAA BEHIND THIS SYSTEM WILL BRING OUR COOLEST TEMPS THUS FAR THIS SEASON TO OUR CWA MONDAY NIGHT. HAVE TRENDED SLIGHTLY COOLER ON MONDAY NIGHT/S LOWS FROM THE PREVIOUS FCST. PATCHY FROST WILL BE A POSSIBILITY IN OUR NORTHWESTERN CWA...GIVEN TEMPS IN THE MIDDLE 30S...ALONG WITH MINIMAL CLOUD COVER AND WIND. HAVE INSERTED PATCHY FROST WORDING THERE. TUESDAY WILL BRING RELATIVELY COOL TEMPS DURING THE DAYTIME TOO...AT LEAST ACROSS THE EASTERN HALF OF THE CWA...AS THE LONG WAVE TROF WILL BE SLOW TO LEAVE. TEMPS ARE A CHALLENGE...WITH THE POSSIBILITY OF THE WESTERN THIRD OF THE CWA SEEING A DECENT WARM UP ESPECIALLY IF THE CLOUDS MOVE OUT. REINFORCING SHOT OF COOL AIR WILL ARRIVE WEDNESDAY NIGHT INTO THURSDAY...IN CONJUNCTION WITH A POTENT SHORTWAVE DROPPING SOUTH FROM CANADA. MODELS SHOW CONSIDERABLE DIVERGENCE LATE IN THE FORECAST PERIOD AND BEYOND. ECMWF BRINGS ANOTHER LONG WAVE TROF SOUTH INTO THE NORTH CENTRAL U.S. FRIDAY NIGHT INTO SATURDAY...AND THEN ATTEMPTS TO DEVELOP A CLOSED H5 LOW OVER ARKANSAS BY SUNDAY NIGHT. THE GFS IS FASTER WITH THE LONG WAVE TROF...BRINGING IT INTO THE NORTH CENTRAL U.S. DURING THE DAY ON FRIDAY...AND THEN PUSHES IT TO OUR EAST WITHOUT A CLOSED LOW DEVELOPING. IF THE ECMWF WERE TO VERIFY THEN THE UNSETTLED WX MAY LINGER LONGER IN OUR AREA. && .AVIATION...16/06Z MVFR STRATUS DECK STILL PROGGED TO MOVE NORTHWARD OVERNIGHT AND MAINLY AFFECT DSM AND FOD BY AROUND 10Z. CLOUD DECK MAY PUSH AS FAR EAST AS OTM...BUT HAD LOW CONFIDENCE WITH ANY MENTION OF MVFR AS LATEST HRRR AND WRF MODELS KEEP DECK TO THE WEST. ENOUGH MIXING SUNDAY AFTERNOON FOR GUSTS IN THE MID-UPPER TEENS. OTHERWISE...INCREASING HIGH CLOUDS TOMORROW NIGHT WITH APPROACHING TROUGH. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...MS SEP 12 LONG TERM...ZOGG AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
317 AM CDT SUN SEP 16 2012 .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 310 AM CDT SUN SEP 16 2012 THE MAIN FORECAST CHALLENGES ARE AREAS OF DENSE FOG THIS MORNING. LIGHT MOIST UPSLOPE FLOW AHEAD OF A LEE TROUGH THIS MORNING WILL CONTINUE TO ADVECT HIGHER DEWPOINTS WESTWARD INTO OUR WESTERN COUNTIES UNDER CLEAR SKIES. A WEAK WARM FRONT AND WIND SHIFT TO THE SOUTH BY 12Z FROM WAKEENEY SOUTH TO DODGE CITY AND ASHLAND MAY HOWEVER LIMIT DENSE FOG FORMATION WEST OF THAT LINE AS UPSLOPE ENDS. ALREADY PRATT SHOWING 2 MILES AND OVERCAST 100 FEET. NEW REPORTS UNDER 1/4 MILE AND FOG COMING IN FROM PRATT AND HAYS SO WILL GO AHEAD AND ISSUE A DENSE FOG ADVISORY FROM HAYS SOUTH TO GREENSBURG AND EAST TO PRATT THROUGH 10 AM. THE DENSE FOG SHOULD QUICKLY CLEAR BY MID MORNING AS LIGHT SOUTH WINDS CONTINUE AND WITH A VERY SHALLOW MOIST LAYER. A STRONG UPPER LEVEL SHORTWAVE TROUGH WILL DIG INTO THE NORTHERN HIGH PLAINS BY THIS EVENING AND THEN DIG INTO THE CENTRAL PLAINS BY MONDAY MORNING. THIS FEATURE WILL PUSH A STRONG COLD FRONT ACROSS WESTERN KANSAS BY EARLY MORNING WITH THE FRONT RUNNING FROM NEAR SAINT JOHN TO ASHLAND. SOUTH WINDS OVERNIGHT WILL SHIFT ABRUPTLY TO THE NORTH AT 20 TO 35 MPH AND GUSTY WITH THE COLD FRONT. ONLY SOME MID TO HIGH LEVEL CLOUDS ARE FORECAST WITH AND BEHIND THE COLD FRONT. HIGHS WILL BE WARMER WITH 850 TEMPS RISING TO AROUND 20C WITH A WEAK WARM FRONT AND RANGE FROM THE MID 80S TO UPPER 80S WEST TO LOW TO MID 80S EAST. OVERNIGHT LOWS WILL RANGE FROM THE UPPER 40S TO LOWER 50S WEST AND NORTH BEHIND THE COLD FRONT TO THE MID TO UPPER 50S IN OUR SOUTHEAST FA FROM SAINT JOHN TO ASHLAND AND EAST. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 310 AM CDT SUN SEP 16 2012 THE COLD FRONT EXPECTED MONDAY MORNING APPEARS THE HAVE A RELATIVELY TIGHT SURFACE PRESSURE GRADIENT OF AROUND 8 MB ACROSS WESTERN KANSAS. LARGE DIFFERENCES EXIST IN THE WIND SPEED OUTPUT BETWEEN THE GFS MOS - ECMWF AND NAM MODELS. IT IS PROBABLE THAT A FEW HOURS OF WIND ADVISORY CRITERIA WIND SPEEDS WILL BE MET. HOWEVER, GIVEN THE LACK LUSTER SPEEDS OF THE ECMWF AND EVEN THE MOS IN CENTRAL KANSAS, WE WILL HOLD OFF ON ANY ADVISORY ISSUING NOW AND DEFER TO CLOSER TO THE EVENT. IT DOES APPEAR TO BE SHAPING UP AS A TYPICAL MARGINAL OR LOW END WIND EPISODE. THE COOLER AIR USHERED IN WILL LIKELY TEMPER HIGHS ON MONDAY INTO THE UPPER 60S. SOUTH CENTRAL KANSAS WILL PROBABLY BE WARMER SINCE THE AREA WOULD REMAIN IN THE WARM SECTOR LONGER. THE DRY AIR LEFT IN THE WAKE OF THE FRONT SHOULD PROMOTE STRONG LONGWAVE RADIATIONAL COOLING OVERNIGHT, BUT THIS ALSO COULD BE MODIFIED SLIGHTLY BY MID TO UPPER LEVEL CLOUDS ASSOCIATED WITH THE STRONG UPPER JET MOVING THROUGH THE CENTRAL PLAINS. TEMPERATURES BY EARLY TUESDAY SHOULD FALL INTO THE LOW 40S ACROSS A BROAD AREA. NORTHWEST FLOW WILL PERSIST ALOFT ACROSS THE AREA. THE SURFACE RESPONSE WILL BE TO CREATE TROUGHING ACROSS EASTERN COLORADO, AND A WARMING TREND AS HIGHER TEMPERATURE BOUNDARY LAYER AIR OVERSPREADS SOUTHWEST KANSAS. WEDNESDAY CONTINUES TO LOOK LIKE THE WARMEST DAY WITH POTENTIAL FOR ADIABATICALLY WARMED AIR FROM DOWNSLOPE WINDS. THE REMAINDER OF THE EXTENDED PERIOD LOOKS TO REMAIN DRY WITH NEAR NORMAL TEMPERATURES FOR MID TO LATE SEPTEMBER. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1230 AM CDT SUN SEP 16 2012 LIGHT MOIST UPSLOPE FLOW CONTINUES AHEAD OF A LEE SIDE TROUGH INTO THIS MORNING. NEW HRRR MODEL UPDATE CONTINUES TO SHOW AREAS OF SHALLOW ADVECTION/RADIATION FOG DEVELOPING AFTER 09Z TILL AROUND 15Z AT THE TAF SITES THIS MORNING. HOWEVER NEW NAM SHOWING LIGHT UPSLOPE BECOMING LIGHT SOUTH BY 09-12Z FROM KGCK TO KDDC WITH NOT AS MUCH FOG. NEW RAP SHOWING POSSIBLE STRATUS AND DENSE FOG EAST OF A LINE FROM WAKEENEY TO DODGE CITY AND ASHLAND. WILL KEEP A TEMPO GROUP GOING FOR SOME IFR VSBYS BETWEEN 09-15Z FOR THE TAF SITES WITH RAPID CLEARING AFTER THAT. LIGHT SSE WINDS CONTINUE AHEAD OF A COLD FRONT FORECAST TO BE NEAR KGLD BY 06Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 84 50 68 42 / 0 0 10 10 GCK 86 49 68 42 / 0 0 10 0 EHA 87 50 68 47 / 0 0 20 10 LBL 86 49 69 44 / 0 0 20 10 HYS 85 49 69 42 / 0 10 20 10 P28 84 59 77 46 / 0 0 20 10 && .DDC WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY FROM 3 AM TO 10 AM CDT THIS MORNING FOR KSZ031-046-065-066-079>081. && $$ SHORT TERM...KRUSE LONG TERM...RUSSELL AVIATION...KRUSE
AREA FORECAST DISCUSSION...UPDATED
NWS DODGE CITY KS
1242 AM CDT SUN SEP 16 2012 ...UPDATED FOR AVIATION... .SHORT TERM...(THIS EVENING THROUGH TOMORROW) ISSUED AT 210 PM CDT SAT SEP 15 2012 FOR TONIGHT, HIGH PRESSURE OVERHEAD WILL ALLOW CLEAR OR CLEARING SKIES, LIGHT SOUTHEAST WINDS IN OUR CENTRAL AND EAST, BUT A TROUGH IN COLORADO SHOULD TURN WINDS LIGHT SOUTHWEST IN OUR WESTERN COUNTIES. ALTHOUGH ONLY 5 TO 10 MPH SOUTHWEST WINDS WILL BE OVER OUR WESTERN COUNTIES, THINK THE UPSLOPE FLOW AFFECT WILL HELP TEMPERATURES FROM FALLING AS PREVIOUSLY FORECAST. I RAISED MINIMUM TEMPERATURES IN OUR CENTRAL AND WEST, WHICH NOW FIT BETTER WITH OUR ISC NEIGHBORS. REVIEWED LAST NIGHT LOWS, WITH GCK AND HYS BOTTOMING OUT AT 41F, AND THINK THEY SHOULD BE NEAR THAT LEVEL IN THE WEST TONIGHT. ALL MODEL GUIDANCE IS EVEN HIGHER, IN THE MID 40S OUT WEST, BUT DID NOT WANT TO SEE-SAW BACK AND FORTH TOO MUCH. IN THE NEARER TERM, THE NAM AND HRRR MODELS BOTH PRODUCED A LITTLE LIGHT RAIN IN MY EXTREME SOUTHEAST BY 19Z TODAY. SINCE THIS HAS NOT MATERIALIZED, DECIDED TO LEAVE POPS OUT OF OUR SOUTHEAST COUNTIES SUCH AS COMANCHE AND BARBER. SUNDAY WILL SEE THE SURFACE TROUGH IN OUR WESTERN COUNTIES, PERHAPS AS FAR EAST AT KEARNY, GRANT AND STEVENS COUNTIES. WINDS WILL SHIFT SOUTH AND BY AFTERNOON INCREASE INTO THE 12 TO 15 MPH RANGE, GUSTING TO NEAR 20 MPH. THIS SOUTH WIND WILL AID IN TRANSPORTING WARMER AIR INTO SOUTHWESTERN KANSAS, ALLOWING MAXIMUM TEMPERATURES TO WARM APPROXIMATELY 10F DEGREES MORE THAN TODAY. SUNDAY`S HIGHS SHOULD RANGE FROM 84F IN HAYS AND DODGE CITY TO 89F IN SYRACUSE. HIGH PRESSURE ALOFT OVER THE PLAINS WILL STILL KEEP A LOT OF SUNSHINE OVERHEAD, WHICH WILL ALSO AID IN WARMING UP THE SURFACE. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 218 PM CDT SAT SEP 15 2012 AN UPPER LEVEL TROUGH WILL EXIT CANADA AND MOVE SOUTHEAST ACROSS THE NORTHERN PLAINS SUNDAY NIGHT AND MONDAY. AS THIS SYSTEM CROSSES THE NORTHERN PLAINS A COLD FRONT WILL MOVE ACROSS WESTERN KANSAS. PRECIPITATION CHANCES WITH THIS COLD FRONT AT THIS TIME STILL APPEARS SMALL. IF PRECIPITATION DOES OCCUR IT WILL BE ON MONDAY AS THE UPPER TROUGH CROSSES PORTIONS OF NORTH CENTRAL KANSAS. ANOTHER AREA WHERE A FEW SHOWERS OR EVEN A THUNDERSTORM MAY DEVELOP WILL BE IN FAR SOUTHWEST KANSAS NEAR THE LEFT EXIT REGION OF AN UPPER LEVEL JET. GIVEN THE EXPECTED CLOUD COVER AND THE COOLING THAT IS FORECAST BEHIND THIS FRONT IN THE 925-850MB LEVEL WILL TREND HIGHS DOWN A COUPLE OF DEGREES AND FAVOR THE COOLEST MODEL GUIDANCE. HIGHS MONDAY MAY STRUGGLE TO REACH THE UPPER 60S ACROSS PORTIONS OF WESTERN AND NORTH CENTRAL KANSAS. GUSTY NORTH WINDS WILL DEVELOP BEHIND THIS FRONT EARLY MONDAY. NAM MEAN MIXED LAYER WINDS SUGGESTING SUSTAINED WIND SPEEDS OF 30 TO 35 MPH AT 15Z AND 18Z MONDAY. GFS WAS A LITTLE WEAKER WITH THESE MIXED LAYER WINDS BUT GIVEN THE MAGNITUDE OF THE COLD AIR ADVECTION DEVELOPING EARLY MONDAY WILL LEAN TOWARDS THE STRONGER NAM WINDS AT THIS TIME. BY MONDAY NIGHT THE UPPER LEVEL TROUGH WILL MOVE EAST OF THE AREA AS AN AREA OF HIGH PRESSURE AT THE SURFACE BEGINS TO SETTLE INTO KANSAS. SKIES MAY BE CLEAR EARLY BUT BASED ON THE GFS AND ECMWF SOME 700MB MOISTURE AND WARM AIR ADVECTION IMPROVES DURING THE OVERNIGHT HOURS ACROSS WESTERN KANSAS. GIVEN LIGHT WINDS AND DEWPOINT IN THE UPPER 30S TO LOWER 40S WILL FAVOR THE COOLER GUIDANCE FOR OVERNIGHT TEMPERATURES BUT AM RELUCTANT TO GO MUCH LOWER THAN THE MID 40S GIVEN THE POTENTIAL FOR SOME CLOUD COVER TOWARDS DAYBREAK. ON TUESDAY A TROUGH OF LOW PRESSURE A THE SURFACE WILL DEVELOP ALONG THE LEE OF THE ROCKIES AS A NORTHWEST FLOW PERSISTS. 850MB TEMPERATURE TRENDS TUESDAY AND WEDNESDAY CONTINUES TO SUPPORT HIGHS REBOUNDING BACK INTO THE 80S. THIS WARM UP HOWEVER WILL BE SHORT LIVED AS ANOTHER COLD FRONT IS FORECAST TO MOVE SOUTH ACROSS THE CENTRAL PLAINS WEDNESDAY NIGHT OR EARLY THURSDAY. NOT ONLY WILL THIS FRONT BRING COOLER TEMPERATURES BACK TO WESTERN KANSAS BUT THERE MAY ALSO BE A SLIGHT CHANCE FOR THUNDERSTORMS AS WELL AS ANOTHER UPPER LEVEL TROUGH CROSSES THE NORTHERN PLAINS. AT THIS TIME MODELS APPEAR TO BE STRUGGLING WITH THE TRACK AND STRENGTH OF THIS NEXT UPPER LEVEL SYSTEM. CONFIDENCE IS NOT HIGH ON WHICH MAY BE MORE CORRECT SO WILL STAY CLOSE TO CONSENSUS FROM THE CREXTENDFCST_INT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1230 AM CDT SUN SEP 16 2012 LIGHT MOIST UPSLOPE FLOW CONTINUES AHEAD OF A LEE SIDE TROUGH INTO THIS MORNING. NEW HRRR MODEL UPDATE CONTINUES TO SHOW AREAS OF SHALLOW ADVECTION/RADIATION FOG DEVELOPING AFTER 09Z TILL AROUND 15Z AT THE TAF SITES THIS MORNING. HOWEVER NEW NAM SHOWING LIGHT UPSLOPE BECOMING LIGHT SOUTH BY 09-12Z FROM KGCK TO KDDC WITH NOT AS MUCH FOG. NEW RAP SHOWING POSSIBLE STRATUS AND DENSE FOG EAST OF A LINE FROM WAKEENEY TO DODGE CITY AND ASHLAND. WILL KEEP A TEMPO GROUP GOING FOR SOME IFR VSBYS BETWEEN 09-15Z FOR THE TAF SITES WITH RAPID CLEARING AFTER THAT. LIGHT SSE WINDS CONTINUE AHEAD OF A COLD FRONT FORECAST TO BE NEAR KGLD BY 06Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 51 67 42 79 / 10 10 10 0 GCK 51 67 42 79 / 10 10 0 0 EHA 53 67 47 80 / 10 20 10 0 LBL 54 68 44 80 / 0 20 10 0 HYS 50 68 42 76 / 10 20 10 0 P28 57 76 46 78 / 10 20 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...BURKE LONG TERM...BURGERT AVIATION...KRUSE
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1111 PM MDT SAT SEP 15 2012 .UPDATE... ISSUED AT 1047 PM MDT SAT SEP 15 2012 INCREASED CLOUD COVER...EXTENDED AREA OF PATCHY FOG FURTHER WEST...AND BUMPED UP LOW TEMPS ACROSS EASTERN AREAS WHERE TD VALUES IN THE MID 50S ARE CURRENTLY REPORTED. WITH SE FLOW ALREADY ADVECTING GOOD BL MOISTURE INTO EASTERN PARTS OF THE CWA...THINK FOG/STRATUS POTENTIAL IS INCREASED OVER OUR CWA. IM STILL NOT SURE ABOUT THE COVERAGE/VISIBILITY AT THIS POINT...AND HOW FAR WEST TO GO WITH FOG. HRRR IS MOST BULLISH ON BRINGING DENSE FOG INTO OUR CWA BY 12Z. LATEST RUC SHOWS BETTER VSBY VALUES...HOWEVER STILL SHOWS TO THE GOOD BL MOISTURE IN PLACE AROUND THE SAME TIME AS HRRR. NEITHER MODEL WOULD SUPPORT FOG MUCH FURTHER WEST THAN A TRENTON TO LEOTI LINE AT THIS POINT. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 1233 PM MDT SAT SEP 15 2012 MAIN CONCERN FOR THE SHORT TERM FORECAST WILL CENTER AROUND TEMPS AND FIRE WX CONCERNS PRIOR TO PASSAGE OF COLD FRONT SUNDAY NIGHT. ALTHOUGH MID LEVEL LAPSE RATES STEEPEN THROUGH THE NIGHT AND THROUGH THE MORNING HOURS...BUT WITH VERY DRY AIR MASS BUILDING INTO THE AREA...APPEARS UNLIKELY THAT ANY ASCENT WITH APPROACHING TROUGH AND COLD FRONT WOULD BE ENOUGH TO SATURATE PARCELS AND REALIZE ANY OF THE INSTABILITY. MIXED LAYER PROFILES SUPPORT DEWPOINTS FALLING TO LOWER VALUES THAN TODAY...WITH FULLY MIXED PROFILES INDICATING SOME DEWPOINTS IN THE TEENS POSSIBLE. WITH TEMPERATURES IN THE UPPER 80S TO LOW 90S AND DEWPOINTS LIKELY BEING IN THE LOWER 20S THINK WIDESPREAD HUMIDITIES IN THE 5-15 PERCENT RANGE IS LIKELY ACROSS THE AREA. MIXED LAYER WINDS OFF OF NAM AND GFS DO NOT SUPPORT MUCH IN THE WAY OF WIND SPEEDS SO DO NOT ANTICIPATE THE NEED FOR FIRE WX WATCH OR WARNING. HOWEVER...SHOULD COLD FRONT SPEED UP AND ENTER THE AREA AROUND THE 00Z TIME FRAME THAT COULD INCREASE FIRE DANGER QUITE A BIT. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 1244 PM MDT SAT SEP 15 2012 PATTERN WILL REMAIN VIRTUALLY UNCHANGED THROUGH THE LONG TERM PERIOD WITH A TROUGH NEAR THE GREAT LAKES AND RIDGE NEAR THE FOUR CORNERS RESULTING IN NORTHWEST FLOW OVER THE CENTRAL PLAINS. A SHORTWAVE TROUGH EMBEDDED IN THE FLOW WILL BRING A COLD FRONT THROUGH THE FORECAST AREA SUNDAY NIGHT. LOW LEVELS ARE VERY DRY...BUT CANNOT RULE OUT AN ISOLATED LIGHT RAIN SHOWER SUNDAY NIGHT OR MONDAY. GUSTY NORTH WINDS CAN BE EXPECTED WITH THE FRONT LATE SUNDAY NIGHT AND MONDAY MORNING. TEMPERATURES WILL BE BELOW NORMAL ON MONDAY WITH LIMITED SUN. THE REST OF THE WEEK WILL SEE A COUPLE OF DRY FRONTAL PASSAGES AND TEMPERATURES NEAR TO SLIGHTLY ABOVE NORMAL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1111 PM MDT SAT SEP 15 2012 VFR CONDITIONS ARE EXPECTED TO PREVAIL AT KGLD THROUGH THE TAF PERIOD. MVFR CONDITIONS ARE POSSIBLE OVER KMCK AROUND 12Z AS FOG/STRATUS DEVELOP EAST OF THE TERMINAL IN RESPONSE TO GOOD BL MOISTURE ADVECTING IN FROM THE SE. CANT RULE OUT CONDITIONS LOWER THAN MVFR...HOWEVER AT THIS POINT LATEST SHORT RANGE GUIDANCE WOULD KEEP IFR/LIFR JUST EAST OF MCK. LIGHT SOUTHERLY WINDS WILL INCREASE SOME DURING THE DAY SUNDAY WITH AFTERNOON GUSTS AROUND 15KT. WINDS WILL SHIFT TO THE NORTH/NORTHWEST LATE SUNDAY EVENING AS A FRONT DROPS SOUTH OVER BOTH TERMINALS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...DR SHORT TERM...JRM LONG TERM...024 AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1054 PM MDT SAT SEP 15 2012 .UPDATE... ISSUED AT 1047 PM MDT SAT SEP 15 2012 INCREASED CLOUD COVER...EXTENDED AREA OF PATCHY FOG FURTHER WEST...AND BUMPED UP LOW TEMPS ACROSS EASTERN AREAS WHERE TD VALUES IN THE MID 50S ARE CURRENTLY REPORTED. WITH SE FLOW ALREADY ADVECTING GOOD BL MOISTURE INTO EASTERN PARTS OF THE CWA...THINK FOG/STRATUS POTENTIAL IS INCREASED OVER OUR CWA. IM STILL NOT SURE ABOUT THE COVERAGE/VISIBILITY AT THIS POINT...AND HOW FAR WEST TO GO WITH FOG. HRRR IS MOST BULLISH ON BRINGING DENSE FOG INTO OUR CWA BY 12Z. LATEST RUC SHOWS BETTER VSBY VALUES...HOWEVER STILL SHOWS TO THE GOOD BL MOISTURE IN PLACE AROUND THE SAME TIME AS HRRR. NEITHER MODEL WOULD SUPPORT FOG MUCH FURTHER WEST THAN A TRENTON TO LEOTI LINE AT THIS POINT. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 1233 PM MDT SAT SEP 15 2012 MAIN CONCERN FOR THE SHORT TERM FORECAST WILL CENTER AROUND TEMPS AND FIRE WX CONCERNS PRIOR TO PASSAGE OF COLD FRONT SUNDAY NIGHT. ALTHOUGH MID LEVEL LAPSE RATES STEEPEN THROUGH THE NIGHT AND THROUGH THE MORNING HOURS...BUT WITH VERY DRY AIR MASS BUILDING INTO THE AREA...APPEARS UNLIKELY THAT ANY ASCENT WITH APPROACHING TROUGH AND COLD FRONT WOULD BE ENOUGH TO SATURATE PARCELS AND REALIZE ANY OF THE INSTABILITY. MIXED LAYER PROFILES SUPPORT DEWPOINTS FALLING TO LOWER VALUES THAN TODAY...WITH FULLY MIXED PROFILES INDICATING SOME DEWPOINTS IN THE TEENS POSSIBLE. WITH TEMPERATURES IN THE UPPER 80S TO LOW 90S AND DEWPOINTS LIKELY BEING IN THE LOWER 20S THINK WIDESPREAD HUMIDITIES IN THE 5-15 PERCENT RANGE IS LIKELY ACROSS THE AREA. MIXED LAYER WINDS OFF OF NAM AND GFS DO NOT SUPPORT MUCH IN THE WAY OF WIND SPEEDS SO DO NOT ANTICIPATE THE NEED FOR FIRE WX WATCH OR WARNING. HOWEVER...SHOULD COLD FRONT SPEED UP AND ENTER THE AREA AROUND THE 00Z TIME FRAME THAT COULD INCREASE FIRE DANGER QUITE A BIT. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 1244 PM MDT SAT SEP 15 2012 PATTERN WILL REMAIN VIRTUALLY UNCHANGED THROUGH THE LONG TERM PERIOD WITH A TROUGH NEAR THE GREAT LAKES AND RIDGE NEAR THE FOUR CORNERS RESULTING IN NORTHWEST FLOW OVER THE CENTRAL PLAINS. A SHORTWAVE TROUGH EMBEDDED IN THE FLOW WILL BRING A COLD FRONT THROUGH THE FORECAST AREA SUNDAY NIGHT. LOW LEVELS ARE VERY DRY...BUT CANNOT RULE OUT AN ISOLATED LIGHT RAIN SHOWER SUNDAY NIGHT OR MONDAY. GUSTY NORTH WINDS CAN BE EXPECTED WITH THE FRONT LATE SUNDAY NIGHT AND MONDAY MORNING. TEMPERATURES WILL BE BELOW NORMAL ON MONDAY WITH LIMITED SUN. THE REST OF THE WEEK WILL SEE A COUPLE OF DRY FRONTAL PASSAGES AND TEMPERATURES NEAR TO SLIGHTLY ABOVE NORMAL. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 506 PM MDT SAT SEP 15 2012 VFR CONDITIONS ARE EXPECTED AT BOTH KGLD AND KMCK THROUGH THE TAF PERIOD. THERE IS A SMALL CHANCE FOR FOG DEVELOPMENT IN PROXIMITY TO KMCK...HOWEVER CONFIDENCE IS MUCH HIGHER THAN ANY FOG/LOW STRATUS WILL REMAIN EAST. WINDS WILL GENERALLY REMAIN OUT OF THE SOUTH AND SOUTHWEST BELOW 12KT AT KGLD. AT KMCK WINDS OVERNIGHT WILL BE LIGHT AND VARIABLE...WITH SOUTH WINDS SUNDAY AFTERNOON GUSTING AROUND 15KT. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...DR SHORT TERM...JRM LONG TERM...024 AVIATION...DR
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
136 AM EDT SUN SEP 16 2012 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 339 PM EDT SAT SEP 15 2012 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A WNW FLOW ALF OVER THE UPR GRT LKS TO THE W OF SLOWLY DEPARTING TROF IN QUEBEC AND E OF MORE ZONAL FLOW OVER THE NRN ROCKIES. SFC HI PRES UNDER THE CONFLUENT UPR FLOW IN THE GRT LKS IS CENTERED OVER SE ONTARIO JUST E OF THE SAULT. SOME SC LINGERS OVER THE ERN CWA EARLY THIS AFTN IN ASSOCIATION WITH DEPARTING H85 THERMAL TROF/LINGERING LLVL MSTR SHOWN ON THE 12Z APX RAOB. BUT AS THE HI IS SHIFTING TO THE E...THE SSW RETURN FLOW ON ITS WESTERN FLANK IS DRAWING WARMER/DRIER AIR NOTED TO THE W BACK INTO THE UPR LKS. 12Z H85 TEMPS ARE AS HI AS 20C AT BISMARCK. 12Z H85-7 DEWPT DEPRESSIONS ARE 20 TO 25C IN THE NRN PLAINS...WHERE PWAT IS GENERALLY 0.25 TO 0.50 INCH...AS LITTLE AS 50 PCT OF NORMAL. MOISTER AIR AT H925-85 LURKS TO THE S IN KANSAS/ MISSOURI. TONIGHT...AS THE HI TO THE E DRIFTS FARTHER AWAY UNDER WNW FLOW ALF...THE LLVL WIND IS FCST TO SHIFT TO THE WSW IN ADVANCE OF LO PRES TROF APRCHG FM THE W AHEAD OF SHRTWV EMBEDDED IN THE ZONAL FLOW ALONG THE NDAKOTA/CNDN BORDER THIS MRNG. THIS FLOW IS PROGGED TO ADVECT THE MUCH WARMER H85 AIR TO THE W THIS MRNG INTO THE UPR LKS...WITH H85 TEMPS FCST TO RISE AS HI AS 16-18C AT IWD BY 12Z SUN. ANY LINGERING LO CLDS OVER THE E SHOULD DISSIPATE EARLY WITH THE ARRIVAL OF THIS WARMER AND DRIER AIR. ALTHOUGH THE AIRMASS IS PROGGED TO REMAIN DRY THRU THE NGT...INCRSG H925 WINDS UP TO 30-35KTS LATE AS WELL AS THE ARRIVAL OF SOME PATCHY HI CLDS INDICATE TNGT WL BE MUCH WARMER THAN THIS MRNG. EXPECT THE HIEST MIN TEMPS OVER THE W AND NCNTRL NEAR LK SUP. SUN...INCOMING LO PRES TROF IS PROGGED TO DRIFT INTO THE WRN CWA IN THE AFTN AND INTERACT WITH H85 THERMAL RDG/AXIS OF H85 TEMPS IN THE 14-15C RANGE IN PLACE. ALTHOUGH MODELS INDICATE SW FLOW IN ADVANCE OF THE TROF WL ADVECT MOISTER LLVL AIR IN KS/MO THIS MRNG INTO THE UPR LKS...VERY DRY H85-7 AIR IN THE NRN PLAINS/ADJOINING SRN CAN AND LACK OF SGNFT DYNAMIC FORCING TO ERODE MID LVL CAPPING/CAUSE H5 FALLS WL BE LIMITING FACTORS FOR PCPN. EVEN WITH THESE NEGATIVES... SOME MODELS...ESPECIALLY THE CONSISTENT 12Z GFS...DO GENERATE SOME PCPN OVER MAINLY THE NRN TIER COUNTIES ALONG AND AHEAD OF THE INCOMING TROF. CONSIDERING THE NEGATIVES...OPTED TO FOLLOW THE DRIER 12Z NAM/LOCAL WRF-ARW MODELS AND MAINTAIN A PCPN-FREE FCST FOR MOST OF THE CWA. DID RETAIN GOING SCHC POPS OVER WRN AND NCNTRL LK SUP CLOSER TO MORE SUBSTANTIAL H5 FALLS ASSOCIATED WITH DEEPENING TROF IN SCNTRL CAN. FCST STEEP H7-5 LAPSE RATES IN EXCESS OF 7C/KM WARRANTS A MENTION OF TS IN THIS AREA DESPITE LIMITED MSTR. MIXING TO H8 ON NAM/GFS FCST SDNGS YIELDS HI TEMPS NEAR 80 OVER THE INTERIOR SCNTRL AWAY FM MODERATION OFF LK MI. WITH MORE MID/HI CLDS AND/OR THE ARRIVAL OF THE TROF/WSHFT TO THE W...TEMPS OVER THE W AND NRN TIER WL BE LOWER. THE COMBINATION OF THE UNSEASONABLE WARMTH OVER MAINLY THE SCNTRL...GUSTY WSW WINDS TO 25-30 MPH ENHANCED BY THE DEEPER MIXING...AND MIN RH DIPPING TO ARND 30 PCT AS DEWPTS MIX OUT INTO THE 45-50 RANGE DESPITE SLOW ARRIVAL OF MORE LLVL MSTR LATER IN THE DAY WL LEAD TO AN ELEVATED RISK OF WILDFIRES... ESPECIALLY OVER THE CNTRL AND E WHERE THE PRES GRADIENT WL REMAIN SHARPEST THRU THE DAY. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 339 PM EDT SAT SEP 15 2012 THE MAIN FORECAST CONCERN FOR SUNDAY NIGHT AND MONDAY ARE POPS ASSOCIATED WITH THE UPPER TROUGH AND COLD FRONT MOVING INTO THE UPPER LAKES. SUNDAY NIGHT SHOULD START OUT QUIET DESPITE THE COLD FRONT BEING OVER WESTERN LAKE SUPERIOR. MOISTURE IS VERY LIMITED ALONG THE FRONT SUNDAY EVENING...AND DYNAMICS ARE LACKING DUE TO THE UPPER JET STILL BEING WELL WEST OVER THE UPPER MIDWEST. HOWEVER...THIS IS EXPECTED TO CHANGE LATER SUNDAY NIGHT INTO MONDAY AS THE UPPER TROUGH SHARPENS AS A RESULT OF THE 110 KT UPPER JET DIVING SOUTH FROM THE YUKON SUNDAY NIGHT. THIS WILL ALLOW THE UPSTREAM THERMAL GRADIENT TO TIGHTEN AND ASSOCIATED FRONTOGENETIC CIRCULATION TO STRENGTHEN LATE SUNDAY AND INTO MONDAY AS IT MOVES INTO UPPER MICHIGAN. MEANWHILE...DEEPER PACIFIC ORIGIN MOISTURE WILL MOVE ACROSS THE REGION /WITH PRECIPITABLE WATER VALUES GREATER THAN 1 INCH/ AS SURFACE LOW PRESSURE DEVELOPS ALONG THE FRONT IN RESPONSE TO THE RIGHT ENTRANCE REGION OF THE JET MOVING OVERHEAD. THERE ARE SOME DIFFERENCES BETWEEN THE GFS AND NAM WITH REGARDS TO THE PLACEMENT OF THE LOW AND THE MOVEMENT OF THE COLD FRONT...WITH THE GFS BEING SLOWER AND AS SUCH FURTHER WEST WITH THE LOW PRES DEVELOPMENT COMPARED TO THE NAM. THE NAM TENDS TO AGREE MORE WITH THE 00Z ECMWF AND ALSO HAS SOME SUPPORT FROM SREF MEMBERS. INCREASING 850MB COLD ADVECTION WILL ALLOW FOR INCREASING LAKE INDUCED INSTABILITY LATE MONDAY INTO MONDAY NIGHT ON N-NW PBL WINDS ON THE NW SIDE OF THE LOW. ALL OF THIS SHOULD COMBINE TO GIVE A PERIOD OF STEADY RAIN STARTING LATE SUNDAY NIGHT AND CONTINUING THROUGH MONDAY...AND IN FACT CONTINUING INTO MONDAY NIGHT INTO TUESDAY FOR AREAS NEAR LAKE SUPERIOR. WITH THE LAKE AND TERRAIN ENHANCEMENT DUE TO NORTHERLY FLOW OFF THE LAKE...SOME AREAS CLOSE TO LAKE SUPERIOR COULD SEE 1-1.5 INCHES OF RAIN LATE SUNDAY NIGHT-TUESDAY MORNING. AS SUCH...HAVE OPTED TO MAKE ONLY MINOR TWEAKS TO THE GOING FORECAST FOR SUNDAY NIGHT INTO TUESDAY. DUE TO THE EXTREMELY DRY AIRMASS ALONG AND AHEAD OF THE FRONT...HAVE OPTED TO BACK OFF POPS ESPECIALLY SUNDAY EVENING. ALTHOUGH IT MAY TAKE A LITTLE TIME FOR THE FAR EAST TO SEE STEADY RAIN ON MONDAY DUE TO THE LOW PRESSURE DEVELOPMENT ALONG THE FRONT KEEPING THAT AREA IN THE WARM SECTOR A LITTLE LONGER...THE EXPECTATION IS THAT THE ENTIRE AREA WILL EVENTUALLY SEE RAIN MONDAY. WILL THEREFORE GO WITH CATEGORICAL POPS FOR THE ENTIRE FORECAST AREA ON MONDAY BUT WILL GO WITH THE HIGHEST POPS ACROSS NORTH CENTRAL AND WESTERN UPPER MICHIGAN DUE TO THE EVENTUAL LAKE/TERRAIN ENHANCEMENT DURING THE AFTERNOON. WILL CONTINUE WITH CATEGORICAL POPS NEAR LAKE SUPERIOR ON MONDAY NIGHT WITH NORTHERLY FLOW AND 850MB TEMPS DROPPING TO -3C...ALLOWING FOR LAKE INDUCED EQUILIBRIUM LEVELS ABOVE 20KFT. WOULD NOT BE SHOCKED IF THERE ARE SOME LIGHTNING STRIKES MONDAY NIGHT ESPECIALLY WITH THE UPPER TROUGH OVERHEAD. ALTHOUGH N-NW FLOW CONTINUES INTO TUESDAY...THE PBL FLOW BECOMES NEUTRAL OR EVEN ANTI-CYCLONIC AS THE DAY GOES ON. IN ADDITION...THE DEEP MOISTURE SHOULD BE SCOURED OUT AND THE BEST Q-VECT CONVERGENCE MOVES EAST. DUE TO THE MODERATE LAKE INSTABILITY FROM 850MB TEMPS AROUND -3C COMBINED WITH ONSHORE FLOW...CANNOT REMOVE POPS NEAR THE LAKE...BUT WILL CONTINUE WITH SCATTERED POPS. BY TUESDAY EVENING...IT SHOULD START TO CLEAR OUT AS THE UPR TROUGH MOVES EAST AND THE SFC HIGH MOVES OVERHEAD. ALTHOUGH THE 12Z GFS IS QUITE PROGRESSIVE IN MOVING THE HIGH TO THE EAST TUE NIGHT...THE GEM AND ECMWF ARE CONSISTENT IN SHOWING A SLOWER AND LESS PROGRESSIVE SOLN. WITH THE HIGH BEING OVERHEAD...IT LOOKS LIKE A GOOD RADIATIONAL COOLING NIGHT ESPECIALLY ACROSS THE INTERIOR WEST AWAY FROM ANY REMAINING LAKE CLOUDS...SO AREAS OF FROST ARE EXPECTED...IF NOT A HARD FREEZE. TEMPS FOR MONDAY/TUESDAY WILL REMAIN BELOW NORMAL...ALTHOUGH MONDAY WILL BE WARMER THAN TUESDAY...ESPECIALLY ACROSS THE EAST. WITH 850MB TEMPS AROUND -3C ON TUESDAY AND BLUSTERY N-NW FLOW...EXPECT TEMPS TO STRUGGLE TO REACH 50...ESPECIALLY WHERE IT STAYS CLOUDY FOR MUCH OF THE DAY NEAR LAKE SUPERIOR. IN THE EXTENDED /WED-NEXT SATURDAY/...IT CERTAINLY LOOKS LIKE A AUTUMN PATTERN ACROSS THE GREAT LAKES AS THE PATTERN WILL BE DOMINATED BY AN INTENSIFYING LONGITUDINAL TROUGH ACROSS CENTRAL CANADA AND EXTENDING SOUTHWARD INTO THE GREAT LAKES REGION BY THE END OF THE WEEK. THIS WILL ALLOW FOR THE UNSETTLED AND COOL WEATHER TO CONTINUE. AS FOR THE SPECIFICS...THE FIRST UPPER LOW THAT WILL PLAGUE THE AREA EARLY IN THE WEEK WILL EJECT OUT TUE NIGHT/WED IN RESPONSE TO ANOTHER SHORTWAVE DIVING DOWN THE BACK SIDE OF THE LONG WAVE TROUGH. THIS SHOULD ALLOW FOR BRIEF RIDGING TO BUILD ACROSS THE UPPER GREAT LAKES WED BEFORE THE NEXT SYSTEM MOVES IN AND CLOSES OFF OVER THE GREAT LAKES BY FRI. AS SUCH...WILL CONTINUE WITH CHANCE POPS FOR THE ENTIRE AREA THURSDAY. AS THE EVENT BECOMES A LITTLE CLEARER IN THE NEXT FEW DAYS...POPS WILL LIKELY NEED TO BE INCREASED IN THE FRIDAY/SATURDAY TIME PERIOD AS IT WILL BE COLD ENOUGH ALOFT FOR LAKE ENHANCEMENT AND MOST OF THE NAEFS MEMBERS ALL HAVE RAIN ON FRIDAY INTO SATURDAY. THE UPPER LOW SETTLES OVER THE GREAT LAKES ON SATURDAY...ALTHOUGH THE ECMWF POSITION IS SOUTH OF THE GFS POSITION. REGARDLESS...SATURDAY LOOKS UNSETTLED AND RATHER WET. TEMPS THROUGH THE EXTENDED PERIOD WILL BE BELOW NORMAL. FRIDAY AND ESPECIALLY SATURDAY COULD STRUGGLE TO GET OUT OF THE UPPER 40S IF IT STAYS CLOUDY AND RAINY FOR THE ENTIRE DAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 134 AM EDT SUN SEP 16 2012 VFR CONDITIONS WILL CONTINUE AT KIWD/KCMX/KSAW THRU THIS FCST PERIOD AS LOW-LEVELS REMAIN DRY DESPITE A COLD FRONT PASSING ACROSS THE AREA THIS AFTN/EVENING. TIGHTENING PRES GRADIENT BTWN HIGH PRES TO THE E AND APPROACHING COLD FRONT ACROSS THE NRN PLAINS WILL LEAD TO LLWS OVERNIGHT. LATEST KMQT VAD WIND PROFILE SHOWS SSW WINDS OF 30KT AT 500FT AGL. OTHER THAN WIND SHIFT...COLD FRONT WILL PASS KIWD/KCMX UNEVENTFULLY THIS AFTN AND KSAW IN THE EVENING. IT WILL BE BEYOND THIS FCST PERIOD THAT RAIN DEVELOPS AS DYNAMICS STRENGTHEN WITH TROF DEEPENING INTO THE UPPER MISSISSIPPI VALLEY. IFR CONDITIONS PROBABLE MON. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 339 PM EDT SAT SEP 15 2012 EXPECT ESE WINDS UP TO 20 KTS THIS AFTERNOON TO VEER TO THE WSW TONIGHT INTO SUN AS HI PRES IN SE ONTARIO RETREATS TO THE E AND A LO PRES TROF APPROACHES FROM THE NW. LOW PRESSURE WILL DEVELOP ALONG A COLD FRONT MOVING ACROSS THE UPPER LAKES ON MONDAY. IT WILL DEEPEN AT IT MOVES JUST EAST OF LAKE SUPERIOR ON MONDAY. THE TIGHTENING PRESSURE GRADIENT COMBINED WITH INCREASING LAKE INSTABILITY WILL ALLOW FOR GALE FORCE NORTHERLY WINDS ACROSS CENTRAL LAKE SUPERIOR MONDAY AND THEN ACROSS THE EAST HALF OF LAKE SUPERIOR MONDAY NIGHT. HIGH PRESSURE BUILDS IN TUESDAY NIGHT BEFORE A BROAD AREA OF LOW PRESSURE MOVES SOUTH THU AND FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... GALE WATCH FROM MONDAY EVENING THROUGH TUESDAY MORNING FOR LSZ267. GALE WATCH FROM MONDAY EVENING THROUGH LATE MONDAY NIGHT FOR LSZ266. GALE WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING FOR LSZ264. GALE WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING FOR LSZ263. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...MRD AVIATION...ROLFSON MARINE...KC/MRD
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1022 AM EDT SUN SEP 16 2012 .SYNOPSIS... A NEARLY STATIONARY FRONTAL BOUNDARY ALONG WITH A SERIES OF UPPER IMPULSES WILL PROVIDE A CHANCE OF SHOWERS AND A POSSIBLE THUNDERSTORM MAINLY ACROSS NORTHERN PORTIONS OF THE FORECAST AREA TODAY AND TONIGHT. AN UPPER LEVEL TROUGH AND INCREASING ATMOSPHERIC MOISTURE WILL PROVIDE INCREASING CHANCES OF PRECIPITATION FOR THE REGION LATE MONDAY THROUGH TUESDAY. A COLD FRONT WILL MOVE THROUGH TUESDAY NIGHT OR EARLY WEDNESDAY BRINGING DRIER AIR INTO THE REGION. && .NEAR TERM /THROUGH TONIGHT/... UPDATE: MID-MORNING SATELLITE IMAGE AND RADAR INDICATING THE SURFACE BOUNDARY STILL JUST NORTH OF THE FORECAST AREA. STILL APPEARS THE BEST CHANCE OF SHOWERS WILL BE NORTH OF THE AREA THIS AFTERNOON. NEAR ZONAL FLOW ALOFT. RUC MODEL SHOWS A WEAK UPPER LEVEL RIPPLE TO CROSS THE NORTHERN/CENTRAL MIDLANDS THIS AFTERNOON. SO..POPS AND TEMPS LOOK GOOD. MADE SLIGHT ADJUSTMENTS TO SKY COVER...MAINLY SOUTH. PREVIOUS DISCUSSION: SURFACE BOUNDARY CURRENTLY STRETCHED TO OUR NORTH ACROSS TN AND NC MAY REMAIN NEARLY STATIONARY OR SHIFT SLIGHTLY SOUTH TODAY AND TONIGHT...AS HIGH PRESSURE CURRENTLY CENTERED OVER OHIO SHIFTS EAST TO THE NE/MID ATLANTIC COAST. THE BOUNDARY ALONG WITH DAYTIME HEATING AND A SERIES OF UPPER IMPULSES TO PROVIDE A CHANCE OF PRECIPITATION...MAINLY ACROSS THE NORTHERN FORECAST AREA. CONVECTIVE ANALYSIS INDICATES WEAK INSTABILITY AND WEAK WIND FIELDS. WILL MENTION ISOLATED TO SLIGHT CHANCE THUNDER TO ACCOMPANY THE CHANCE POPS MAINLY NORTH...BUT SEVERE NOT EXPECTED. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... CUTOFF UPPER LOW CURRENTLY OVER W TX...WILL OPEN AND SHIFT TO THE ENE MON/TUE AHEAD OF NORTHERN STREAM KICKER TROUGH DIGGING SE INTO THE PLAINS AND MIDWEST. SURFACE HIGH PRESSURE WILL SHIFT OFF THE EAST COAST WHILE SURFACE LOW DEVELOPS ALONG THE GULF COAST AND SHIFTS RAPIDLY NE AHEAD OF A COLD FRONT. THIS WILL BRING INCREASING MOISTURE INTO OUR REGION. LATEST MODEL RUNS ARE TRENDING A LITTLE SLOWER WITH THE BEST MOISTURE AND POPS. MODELS INDICATE MODERATE INSTABILITY AND SIGNIFICANT 850MB JET AROUND 40KTS. SPC HAS REGION OUTLOOKED IN SLIGHT RISK OF SEVERE THUNDERSTORMS TUESDAY. DRIER AIR WILL ENTER THE REGION BEHIND A COLD FRONT THAT IS PROGGED TO COME THROUGH EITHER LATE TUESDAY NIGHT OR EARLY WED. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... NO CHANGES WERE MADE TO THE ONGOING FORECAST FOR THIS TIME PERIOD. PREVIOUS DISCUSSION...A DEEP MEAN TROUGH WILL HOLD OVER THE CONUS EAST OF THE ROCKY MOUNTAINS THROUGH THE LONG TERM. COOL AND DRY HIGH PRESSURE WILL BUILD EAST FROM THE MIDWEST WEDNESDAY THROUGH FRIDAY. A CLIPPER SYSTEM WILL CROSS THE GREAT LAKES REGION NEXT WEEKEND. THE MAIN MOISTURE SHOULD REMAIN NORTH OF THE AREA. THE WEATHER SHOULD BE DRY. EXPECT HIGHS IN THE MID 70S TO MID 80S WITH LOWS IN THE MID 50S TO MID 60S. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... VFR CONDITIONS EXPECTED THROUGH THE EVENING HOURS. LIGHT WINDS TO BECOME MORE SOUTH TO SOUTHEAST THIS AFTERNOON. WEAK SURFACE FRONT TO SET UP ACROSS THE NORTHERN MIDLANDS THIS AFTERNOON AND BECOME A FOCUS FOR SHOWERS. EXPECT BULK OF SHOWERS TO REMAIN MAINLY NORTH OF THE TAF SITES. LATE NIGHT FOG/STRATUS COULD DEVELOP TOWARD THE END OF THE TAF PERIOD. SINCE CONFIDENCE IS LOW...WILL NOT INCLUDE AT THIS TIME. EXTENDED AVIATION OUTLOOK...VSBY/CIG RESTRICTIONS ASSOCIATED WITH RAIN POSSIBLE MONDAY INTO EARLY WEDNESDAY. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1000 AM CDT SUN SEP 16 2012 ...UPDATED... .UPDATE... ISSUED AT 955 AM CDT SUN SEP 16 2012 UPDATED THE FORECAST FOR MAINLY MAX TEMPS TODAY, LOWERING THEM A BIT IN MY EASTERN ZONES. DENSE FOG THIS MORNING AND LINGERING LOWER CLOUDS THROUGH NOON TO 1 PM CDT WILL SLOW DOWN DAY TIME HEATING. ALSO, THE HRRR, RUC AND NAM MODELS ALL HAVE UPPER 70S FOR HIGH IN THE LARNED AND PRATT AREAS. BUMPED HIGHS DOWN IN THE JETMORE, DODGE CITY AND ASHLAND AREAS TO LOWER 80S. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 310 AM CDT SUN SEP 16 2012 THE MAIN FORECAST CHALLENGES ARE AREAS OF DENSE FOG THIS MORNING. LIGHT MOIST UPSLOPE FLOW AHEAD OF A LEE TROUGH THIS MORNING WILL CONTINUE TO ADVECT HIGHER DEWPOINTS WESTWARD INTO OUR WESTERN COUNTIES UNDER CLEAR SKIES. A WEAK WARM FRONT AND WIND SHIFT TO THE SOUTH BY 12Z FROM WAKEENEY SOUTH TO DODGE CITY AND ASHLAND MAY HOWEVER LIMIT DENSE FOG FORMATION WEST OF THAT LINE AS UPSLOPE ENDS. ALREADY PRATT SHOWING 2 MILES AND OVERCAST 100 FEET. NEW REPORTS UNDER 1/4 MILE AND FOG COMING IN FROM PRATT AND HAYS SO WILL GO AHEAD AND ISSUE A DENSE FOG ADVISORY FROM HAYS SOUTH TO GREENSBURG AND EAST TO PRATT THROUGH 10 AM. THE DENSE FOG SHOULD QUICKLY CLEAR BY MID MORNING AS LIGHT SOUTH WINDS CONTINUE AND WITH A VERY SHALLOW MOIST LAYER. A STRONG UPPER LEVEL SHORTWAVE TROUGH WILL DIG INTO THE NORTHERN HIGH PLAINS BY THIS EVENING AND THEN DIG INTO THE CENTRAL PLAINS BY MONDAY MORNING. THIS FEATURE WILL PUSH A STRONG COLD FRONT ACROSS WESTERN KANSAS BY EARLY MORNING WITH THE FRONT RUNNING FROM NEAR SAINT JOHN TO ASHLAND. SOUTH WINDS OVERNIGHT WILL SHIFT ABRUPTLY TO THE NORTH AT 20 TO 35 MPH AND GUSTY WITH THE COLD FRONT. ONLY SOME MID TO HIGH LEVEL CLOUDS ARE FORECAST WITH AND BEHIND THE COLD FRONT. HIGHS WILL BE WARMER WITH 850 TEMPS RISING TO AROUND 20C WITH A WEAK WARM FRONT AND RANGE FROM THE MID 80S TO UPPER 80S WEST TO LOW TO MID 80S EAST. OVERNIGHT LOWS WILL RANGE FROM THE UPPER 40S TO LOWER 50S WEST AND NORTH BEHIND THE COLD FRONT TO THE MID TO UPPER 50S IN OUR SOUTHEAST FA FROM SAINT JOHN TO ASHLAND AND EAST. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 310 AM CDT SUN SEP 16 2012 THE COLD FRONT EXPECTED MONDAY MORNING APPEARS THE HAVE A RELATIVELY TIGHT SURFACE PRESSURE GRADIENT OF AROUND 8 MB ACROSS WESTERN KANSAS. LARGE DIFFERENCES EXIST IN THE WIND SPEED OUTPUT BETWEEN THE GFS MOS - ECMWF AND NAM MODELS. IT IS PROBABLE THAT A FEW HOURS OF WIND ADVISORY CRITERIA WIND SPEEDS WILL BE MET. HOWEVER, GIVEN THE LACK LUSTER SPEEDS OF THE ECMWF AND EVEN THE MOS IN CENTRAL KANSAS, WE WILL HOLD OFF ON ANY ADVISORY ISSUING NOW AND DEFER TO CLOSER TO THE EVENT. IT DOES APPEAR TO BE SHAPING UP AS A TYPICAL MARGINAL OR LOW END WIND EPISODE. THE COOLER AIR USHERED IN WILL LIKELY TEMPER HIGHS ON MONDAY INTO THE UPPER 60S. SOUTH CENTRAL KANSAS WILL PROBABLY BE WARMER SINCE THE AREA WOULD REMAIN IN THE WARM SECTOR LONGER. THE DRY AIR LEFT IN THE WAKE OF THE FRONT SHOULD PROMOTE STRONG LONGWAVE RADIATIONAL COOLING OVERNIGHT, BUT THIS ALSO COULD BE MODIFIED SLIGHTLY BY MID TO UPPER LEVEL CLOUDS ASSOCIATED WITH THE STRONG UPPER JET MOVING THROUGH THE CENTRAL PLAINS. TEMPERATURES BY EARLY TUESDAY SHOULD FALL INTO THE LOW 40S ACROSS A BROAD AREA. NORTHWEST FLOW WILL PERSIST ALOFT ACROSS THE AREA. THE SURFACE RESPONSE WILL BE TO CREATE TROUGHING ACROSS EASTERN COLORADO, AND A WARMING TREND AS HIGHER TEMPERATURE BOUNDARY LAYER AIR OVERSPREADS SOUTHWEST KANSAS. WEDNESDAY CONTINUES TO LOOK LIKE THE WARMEST DAY WITH POTENTIAL FOR ADIABATICALLY WARMED AIR FROM DOWNSLOPE WINDS. THE REMAINDER OF THE EXTENDED PERIOD LOOKS TO REMAIN DRY WITH NEAR NORMAL TEMPERATURES FOR MID TO LATE SEPTEMBER. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 627 AM CDT SUN SEP 16 2012 MOIST ADVECTION AND RADIATIONAL COOLING AHEAD OF A LEE SIDE TROUGH IN EASTERN COLORADO HAS LED TO AREAS OF SHALLOW DENSE FOG WITH VLIFR TO LIFR CONDITIONS. AS THE SUN COMES UP THE DENSE FOG IS EXPECTED TO BURN OFF RAPIDLY BY AROUND 15Z WITH VFR CONDITIONS. A NORTHERN BRANCH SHORTWAVE TROUGH IS FORECAST TO DIG INTO THE CENTRAL PLAINS TONIGHT PUSHING A STRONG COLD FRONT ACROSS THE TAF SITES WITH LIGHT SOUTH WINDS SHIFTING TO THE NORTH AT 20-35KT. THE COLD FRONT IS FORECAST TO BE NEAR KHYS BY AROUND 09Z, KGCK BY 10Z, AND KDDC BY AROUND 11Z MONDAY MORNING. && .PRELIMINARY POINT TEMPS/POPS... DDC 82 50 68 42 / 0 0 10 10 GCK 85 49 68 42 / 0 0 10 0 EHA 87 50 68 47 / 0 0 20 10 LBL 86 49 69 44 / 0 0 20 10 HYS 80 49 69 42 / 0 10 20 10 P28 82 59 77 46 / 0 0 20 10 && .DDC WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR KSZ030-031- 044>046-063>066-077>081-087>090. && $$ UPDATE...BURKE SHORT TERM...KRUSE LONG TERM...RUSSELL AVIATION...KRUSE
AREA FORECAST DISCUSSION
NWS GOODLAND KS
745 AM MDT SUN SEP 16 2012 .UPDATE... ISSUED AT 735 AM MDT SUN SEP 16 2012 WITH FIRST VISIBLE IMAGES COMING IN THIS MORNING GIVES A GOOD VIEW TO THE EXTENT OF MORNING FOG COVER WHICH INDICATES MOST WIDESPREAD FOG ACROSS THE EXTREME EASTERN FRINGE OF THE AREA. WITH LIGHT WESTERLY FLOW EXTENDING FROM A TRENTON TO GRINNELL LINE...DO NOT THINK FOG WOULD EXPAND ANY FARTHER WEST THAN THAT AND WITH SFC HEATING DEVELOPING HAVE DOUBTS IF IT WILL EXPAND MUCH FROM CURRENT POSITION. HAVE LOWERED COVERAGE TO PATCHY ACROSS WESTERN EXTEND OF ADVISORY AREA AND WANT TO MONITOR AREA FOR POSSIBLE EXPANSION OF FOG COVERAGE BEFORE CLEARING COUNTIES. UPDATE ISSUED AT 513 AM MDT SUN SEP 16 2012 DENSE FOG BEING REPORTED AT HILL CITY (KHLC) PRESENTLY. THIS AIRMASS EXPECTED TO SLOWLY DRIFT WEST PER HRRR WHICH SEEMS TO HAVE A GOOD HANDLE ON CURRENT CONDITIONS. DENSE FOG ADVISORY HAS BEEN ISSUED. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 200 AM MDT SUN SEP 16 2012 FIRST CONCERN THIS MORNING IS FOG. AT 07Z FOG NOW DEVELOPING IN THE HILL CITY AND POSSIBLY NORTON AREAS NEAR A SFC TROUGH. EXPECT THE FOG TO CONTINUE IN THESE AREAS...POSSIBLY A ROW OF COUNTIES FURTHER WEST THROUGH MID MORNING BEFORE THE SFC LOW AND TROUGH START TO MOVE EAST PUSHING THE ABUNDANT LOW LEVEL MOISTURE OUT OF THE AREA. OTHERWISE FOR TODAY EXPECT A SLOWLY INCREASE IN MOSTLY HIGH LEVEL CLOUDS WITH HIGH TEMPERATURES AROUND 85 IN THE NORTON AND HILL CITY AREAS TO THE UPPER 80S TO MID 90S ELSEWHERE...HOTTEST IN THE BENKELMAN AND SAINT FRANCIS AREAS. FOR TONIGHT THROUGH MONDAY FOCUS REMAINS ON A STRONG COLD FRONT AND THE CHANCE ALBEIT SMALL FOR SOME LIGHT RAIN SHOWERS. GOOD AGREEMENT ON BRINGING THE FRONT INTO THE NORTHWEST CORNER OF THE AREA AROUND MIDNIGHT THEN RAPIDLY SOUTH AND THROUGH THE ENTIRE AREA BY SUNRISE MONDAY. STILL LOOKING AT 20 TO 30 MPH WINDS WITH HIGHER GUSTS. THESE WINDS WILL CONTINUE THE EARLY PART OF THE DAY MONDAY BEFORE SLOWLY SUBSIDING THROUGH THE REST OF THE DAY. HIGH TEMPERATURES WILL BE MUCH COOLER WITH MID 60S TO AROUND 70. AS FAR AS PRECIPITATION CHANCES...STILL LOOKING LIKE THE BEST CHANCE WILL BE AFTER MIDNIGHT TONIGHT THROUGH EARLY MONDAY AFTERNOON AS A WEATHER DISTURBANCE AND SOME JET ENERGY MOVE THROUGH THE NORTHWEST FLOW ALOFT. MONDAY NIGHT-TUESDAY NIGHT...HIGH PRESSURE MOVES OVER THE AREA MONDAY NIGHT WITH OVERNIGHT LOWS IN THE UPPER 30S TO LOW 40S. WARMER TEMPERATURES RETURN TUESDAY WITH 75 TO 80 ACROSS THE AREA. LOWS TUESDAY NIGHT NEAR NORMAL. IT APPEARS TO BE DRY THROUGH THE PERIOD. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 200 AM MDT SUN SEP 16 2012 THE PERIOD IS EXPECTED TO BE DRY AS A WEAK RIDGE PERSISTS OVER THE DESERT SOUTHWEST AND A SERIES OF TROUGHS DIG IN THROUGH THE EASTERN 2/3RDS OF THE CONUS. MAY SEE A FEW WEAK AND DRY FRONTAL PASSAGES WITH THE NORTHWEST FLOW OVER THE AREA. THE 12Z/15 AND 00Z/16 EC ARE VERY AGGRESSIVE IN BRINGING A SHORTWAVE TROUGH DEEP INTO THE PLAINS FRIDAY INTO SATURDAY WHICH COULD BRING A SLIGHT CHANCE OF PRECIP...BUT HAVE DECIDED TO KEEP POPS SILENT AS THIS SOLUTION IS AN OUTLIER WRT OTHER GUIDANCE. TEMPERATURES OVER THE PERIOD WILL BE NEAR NORMAL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 552 AM MDT SUN SEP 16 2012 VFR CONDITIONS ARE EXPECTED AT MCK THROUGH MOST OF THE TAF PERIOD. DENSE FOG DEVELOPED EAST OF MCK OVERNIGHT. LOOKING AT THE GOES FOG PRODUCT...REGIONAL OBSERVATIONS...AND REAL TIME OBS AT MCK IT APPEARS THAT THE LOW LEVEL MOISTURE IS VERY CLOSE TO MCK. HAVE INCLUDED A TEMPO GROUP FOR MVFR VISIBILITIES AS PATCHY FOG MAY DEVELOP THIS MORNING DUE TO THE LOW LEVEL MOISTURE...BUT AT THIS TIME DO NOT EXPECT DENSE FOG TO REACH THE AIRPORT. OTHERWISE TODAY WILL HAVE MODERATE WINDS OUT OF THE SOUTH BEFORE A STRONG COLD FRONT PASSAGE LATE TONIGHT. PRECIPITATION CHANCES ARE VERY LOW BUT BEHIND THE FRONT WINDS WILL BE STRONG OUT OF THE NORTH- NORTHEAST AT 20KTS WITH GUSTS TO 30KTS. AT GLD VFR CONDITIONS ARE EXPECTED THROUGH THE ENTIRE PERIOD AS A WEAK TROUGH SITS OVER THE AREA WHICH WILL LIMIT AFTERNOON WINDS. A STRONG COLD FRONT WILL PASS LATE TONIGHT BRINGING CLOUDS AND STRONG WINDS OUT OF THE NORTH WITH GUSTS UP TO 30KTS. && .FIRE WEATHER... ISSUED AT 200 AM MDT SUN SEP 16 2012 CRITICAL FIRE WEATHER CONDITIONS ARE POSSIBLE THIS AFTERNOON FOR COUNTIES INCLUDING HITCHCOCK AND RED WILLOW COUNTIES OF NEBRASKA...RAWLINS...DECATUR...THOMAS AND SHERIDAN COUNTIES OF KANSAS. IN THESE AREAS SOUTH WINDS HAVE THE POTENTIAL TO GUST AROUND 25 MPH WHILE RELATIVE HUMIDITY DROPS BELOW 15 PERCENT. CONFIDENCE NOT HIGH ENOUGH RIGHT NOW FOR A RED FLAG WARNING GIVEN DISAGREEMENT ON THE HANDLING OF THE SFC TROUGH AND SPEED AT WHICH IT MAY OR MAY NOT MOVE EAST ACROSS THE AREA TODAY. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL 11 AM CDT THIS MORNING FOR KSZ003-004- 015-016-029. CO...NONE. NE...DENSE FOG ADVISORY UNTIL 11 AM CDT THIS MORNING FOR NEZ081. && $$ UPDATE...JRM SHORT TERM...99 LONG TERM...JJM AVIATION...99/JJM FIRE WEATHER...99
AREA FORECAST DISCUSSION
NWS GOODLAND KS
553 AM MDT SUN SEP 16 2012 .UPDATE... ISSUED AT 513 AM MDT SUN SEP 16 2012 DENSE FOG BEING REPORTED AT HILL CITY (KHLC) PRESENTLY. THIS AIRMASS EXPECTED TO SLOWLY DRIFT WEST PER HRRR WHICH SEEMS TO HAVE A GOOD HANDLE ON CURRENT CONDITIONS. DENSE FOG ADVISORY HAS BEEN ISSUED. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 200 AM MDT SUN SEP 16 2012 FIRST CONCERN THIS MORNING IS FOG. AT 07Z FOG NOW DEVELOPING IN THE HILL CITY AND POSSIBLY NORTON AREAS NEAR A SFC TROUGH. EXPECT THE FOG TO CONTINUE IN THESE AREAS...POSSIBLY A ROW OF COUNTIES FURTHER WEST THROUGH MID MORNING BEFORE THE SFC LOW AND TROUGH START TO MOVE EAST PUSHING THE ABUNDANT LOW LEVEL MOISTURE OUT OF THE AREA. OTHERWISE FOR TODAY EXPECT A SLOWLY INCREASE IN MOSTLY HIGH LEVEL CLOUDS WITH HIGH TEMPERATURES AROUND 85 IN THE NORTON AND HILL CITY AREAS TO THE UPPER 80S TO MID 90S ELSEWHERE...HOTTEST IN THE BENKELMAN AND SAINT FRANCIS AREAS. FOR TONIGHT THROUGH MONDAY FOCUS REMAINS ON A STRONG COLD FRONT AND THE CHANCE ALBEIT SMALL FOR SOME LIGHT RAIN SHOWERS. GOOD AGREEMENT ON BRINGING THE FRONT INTO THE NORTHWEST CORNER OF THE AREA AROUND MIDNIGHT THEN RAPIDLY SOUTH AND THROUGH THE ENTIRE AREA BY SUNRISE MONDAY. STILL LOOKING AT 20 TO 30 MPH WINDS WITH HIGHER GUSTS. THESE WINDS WILL CONTINUE THE EARLY PART OF THE DAY MONDAY BEFORE SLOWLY SUBSIDING THROUGH THE REST OF THE DAY. HIGH TEMPERATURES WILL BE MUCH COOLER WITH MID 60S TO AROUND 70. AS FAR AS PRECIPITATION CHANCES...STILL LOOKING LIKE THE BEST CHANCE WILL BE AFTER MIDNIGHT TONIGHT THROUGH EARLY MONDAY AFTERNOON AS A WEATHER DISTURBANCE AND SOME JET ENERGY MOVE THROUGH THE NORTHWEST FLOW ALOFT. MONDAY NIGHT-TUESDAY NIGHT...HIGH PRESSURE MOVES OVER THE AREA MONDAY NIGHT WITH OVERNIGHT LOWS IN THE UPPER 30S TO LOW 40S. WARMER TEMPERATURES RETURN TUESDAY WITH 75 TO 80 ACROSS THE AREA. LOWS TUESDAY NIGHT NEAR NORMAL. IT APPEARS TO BE DRY THROUGH THE PERIOD. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 200 AM MDT SUN SEP 16 2012 THE PERIOD IS EXPECTED TO BE DRY AS A WEAK RIDGE PERSISTS OVER THE DESERT SOUTHWEST AND A SERIES OF TROUGHS DIG IN THROUGH THE EASTERN 2/3RDS OF THE CONUS. MAY SEE A FEW WEAK AND DRY FRONTAL PASSAGES WITH THE NORTHWEST FLOW OVER THE AREA. THE 12Z/15 AND 00Z/16 EC ARE VERY AGGRESSIVE IN BRINGING A SHORTWAVE TROUGH DEEP INTO THE PLAINS FRIDAY INTO SATURDAY WHICH COULD BRING A SLIGHT CHANCE OF PRECIP...BUT HAVE DECIDED TO KEEP POPS SILENT AS THIS SOLUTION IS AN OUTLIER WRT OTHER GUIDANCE. TEMPERATURES OVER THE PERIOD WILL BE NEAR NORMAL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 552 AM MDT SUN SEP 16 2012 VFR CONDITIONS ARE EXPECTED AT MCK THROUGH MOST OF THE TAF PERIOD. DENSE FOG DEVELOPED EAST OF MCK OVERNIGHT. LOOKING AT THE GOES FOG PRODUCT...REGIONAL OBSERVATIONS...AND REAL TIME OBS AT MCK IT APPEARS THAT THE LOW LEVEL MOISTURE IS VERY CLOSE TO MCK. HAVE INCLUDED A TEMPO GROUP FOR MVFR VISIBILITIES AS PATCHY FOG MAY DEVELOP THIS MORNING DUE TO THE LOW LEVEL MOISTURE...BUT AT THIS TIME DO NOT EXPECT DENSE FOG TO REACH THE AIRPORT. OTHERWISE TODAY WILL HAVE MODERATE WINDS OUT OF THE SOUTH BEFORE A STRONG COLD FRONT PASSAGE LATE TONIGHT. PRECIPITATION CHANCES ARE VERY LOW BUT BEHIND THE FRONT WINDS WILL BE STRONG OUT OF THE NORTH- NORTHEAST AT 20KTS WITH GUSTS TO 30KTS. AT GLD VFR CONDITIONS ARE EXPECTED THROUGH THE ENTIRE PERIOD AS A WEAK TROUGH SITS OVER THE AREA WHICH WILL LIMIT AFTERNOON WINDS. A STRONG COLD FRONT WILL PASS LATE TONIGHT BRINGING CLOUDS AND STRONG WINDS OUT OF THE NORTH WITH GUSTS UP TO 30KTS. && .FIRE WEATHER... ISSUED AT 200 AM MDT SUN SEP 16 2012 CRITICAL FIRE WEATHER CONDITIONS ARE POSSIBLE THIS AFTERNOON FOR COUNTIES INCLUDING HITCHCOCK AND RED WILLOW COUNTIES OF NEBRASKA...RAWLINS...DECATUR...THOMAS AND SHERIDAN COUNTIES OF KANSAS. IN THESE AREAS SOUTH WINDS HAVE THE POTENTIAL TO GUST AROUND 25 MPH WHILE RELATIVE HUMIDITY DROPS BELOW 15 PERCENT. CONFIDENCE NOT HIGH ENOUGH RIGHT NOW FOR A RED FLAG WARNING GIVEN DISAGREEMENT ON THE HANDLING OF THE SFC TROUGH AND SPEED AT WHICH IT MAY OR MAY NOT MOVE EAST ACROSS THE AREA TODAY. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL 11 AM CDT THIS MORNING FOR KSZ003-004- 015-016-029. CO...NONE. NE...DENSE FOG ADVISORY UNTIL 11 AM CDT THIS MORNING FOR NEZ081. && $$ UPDATE...99 SHORT TERM...99 LONG TERM...JJM AVIATION...99/JJM FIRE WEATHER...99
AREA FORECAST DISCUSSION
NWS GOODLAND KS
517 AM MDT SUN SEP 16 2012 .UPDATE... ISSUED AT 513 AM MDT SUN SEP 16 2012 DENSE FOG BEING REPORTED AT HILL CITY (KHLC) PRESENTLY. THIS AIRMASS EXPECTED TO SLOWLY DRIFT WEST PER HRRR WHICH SEEMS TO HAVE A GOOD HANDLE ON CURRENT CONDITIONS. DENSE FOG ADVISORY HAS BEEN ISSUED. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 200 AM MDT SUN SEP 16 2012 FIRST CONCERN THIS MORNING IS FOG. AT 07Z FOG NOW DEVELOPING IN THE HILL CITY AND POSSIBLY NORTON AREAS NEAR A SFC TROUGH. EXPECT THE FOG TO CONTINUE IN THESE AREAS...POSSIBLY A ROW OF COUNTIES FURTHER WEST THROUGH MID MORNING BEFORE THE SFC LOW AND TROUGH START TO MOVE EAST PUSHING THE ABUNDANT LOW LEVEL MOISTURE OUT OF THE AREA. OTHERWISE FOR TODAY EXPECT A SLOWLY INCREASE IN MOSTLY HIGH LEVEL CLOUDS WITH HIGH TEMPERATURES AROUND 85 IN THE NORTON AND HILL CITY AREAS TO THE UPPER 80S TO MID 90S ELSEWHERE...HOTTEST IN THE BENKELMAN AND SAINT FRANCIS AREAS. FOR TONIGHT THROUGH MONDAY FOCUS REMAINS ON A STRONG COLD FRONT AND THE CHANCE ALBEIT SMALL FOR SOME LIGHT RAIN SHOWERS. GOOD AGREEMENT ON BRINGING THE FRONT INTO THE NORTHWEST CORNER OF THE AREA AROUND MIDNIGHT THEN RAPIDLY SOUTH AND THROUGH THE ENTIRE AREA BY SUNRISE MONDAY. STILL LOOKING AT 20 TO 30 MPH WINDS WITH HIGHER GUSTS. THESE WINDS WILL CONTINUE THE EARLY PART OF THE DAY MONDAY BEFORE SLOWLY SUBSIDING THROUGH THE REST OF THE DAY. HIGH TEMPERATURES WILL BE MUCH COOLER WITH MID 60S TO AROUND 70. AS FAR AS PRECIPITATION CHANCES...STILL LOOKING LIKE THE BEST CHANCE WILL BE AFTER MIDNIGHT TONIGHT THROUGH EARLY MONDAY AFTERNOON AS A WEATHER DISTURBANCE AND SOME JET ENERGY MOVE THROUGH THE NORTHWEST FLOW ALOFT. MONDAY NIGHT-TUESDAY NIGHT...HIGH PRESSURE MOVES OVER THE AREA MONDAY NIGHT WITH OVERNIGHT LOWS IN THE UPPER 30S TO LOW 40S. WARMER TEMPERATURES RETURN TUESDAY WITH 75 TO 80 ACROSS THE AREA. LOWS TUESDAY NIGHT NEAR NORMAL. IT APPEARS TO BE DRY THROUGH THE PERIOD. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 200 AM MDT SUN SEP 16 2012 THE PERIOD IS EXPECTED TO BE DRY AS A WEAK RIDGE PERSISTS OVER THE DESERT SOUTHWEST AND A SERIES OF TROUGHS DIG IN THROUGH THE EASTERN 2/3RDS OF THE CONUS. MAY SEE A FEW WEAK AND DRY FRONTAL PASSAGES WITH THE NORTHWEST FLOW OVER THE AREA. THE 12Z/15 AND 00Z/16 EC ARE VERY AGGRESSIVE IN BRINGING A SHORTWAVE TROUGH DEEP INTO THE PLAINS FRIDAY INTO SATURDAY WHICH COULD BRING A SLIGHT CHANCE OF PRECIP...BUT HAVE DECIDED TO KEEP POPS SILENT AS THIS SOLUTION IS AN OUTLIER WRT OTHER GUIDANCE. TEMPERATURES OVER THE PERIOD WILL BE NEAR NORMAL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1111 PM MDT SAT SEP 15 2012 VFR CONDITIONS ARE EXPECTED TO PREVAIL AT KGLD THROUGH THE TAF PERIOD. MVFR CONDITIONS ARE POSSIBLE OVER KMCK AROUND 12Z AS FOG/STRATUS DEVELOP EAST OF THE TERMINAL IN RESPONSE TO GOOD BL MOISTURE ADVECTING IN FROM THE SE. CANT RULE OUT CONDITIONS LOWER THAN MVFR...HOWEVER AT THIS POINT LATEST SHORT RANGE GUIDANCE WOULD KEEP IFR/LIFR JUST EAST OF MCK. LIGHT SOUTHERLY WINDS WILL INCREASE SOME DURING THE DAY SUNDAY WITH AFTERNOON GUSTS AROUND 15KT. WINDS WILL SHIFT TO THE NORTH/NORTHWEST LATE SUNDAY EVENING AS A FRONT DROPS SOUTH OVER BOTH TERMINALS. && .FIRE WEATHER... ISSUED AT 200 AM MDT SUN SEP 16 2012 CRITICAL FIRE WEATHER CONDITIONS ARE POSSIBLE THIS AFTERNOON FOR COUNTIES INCLUDING HITCHCOCK AND RED WILLOW COUNTIES OF NEBRASKA...RAWLINS...DECATUR...THOMAS AND SHERIDAN COUNTIES OF KANSAS. IN THESE AREAS SOUTH WINDS HAVE THE POTENTIAL TO GUST AROUND 25 MPH WHILE RELATIVE HUMIDITY DROPS BELOW 15 PERCENT. CONFIDENCE NOT HIGH ENOUGH RIGHT NOW FOR A RED FLAG WARNING GIVEN DISAGREEMENT ON THE HANDLING OF THE SFC TROUGH AND SPEED AT WHICH IT MAY OR MAY NOT MOVE EAST ACROSS THE AREA TODAY. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL 11 AM CDT THIS MORNING FOR KSZ003-004- 015-016-029. CO...NONE. NE...DENSE FOG ADVISORY UNTIL 11 AM CDT THIS MORNING FOR NEZ081. && $$ UPDATE...99 SHORT TERM...99 LONG TERM...JJM AVIATION...DR FIRE WEATHER...99
AREA FORECAST DISCUSSION...UPDATED
NWS DODGE CITY KS
536 AM CDT SUN SEP 16 2012 .UPDATE... ISSUED AT 528 AM CDT SUN SEP 16 2012 WENT AHEAD AND EXPANDED THE DENSE FOG ADVISORY WEST TO TREGO, LANE, FINNEY, GRAY, AND MEADE, THEN EAST TO MEDICINE LODGE. LOCAL CALLS TO COUNTIES WERE GETTING WIDESPREAD AREAS OF DENSE FOG WITH VISIBILITIES LESS THAN 1/4 OF A MILE. SATELLITE FOG PRODUCT AND HRRR MESOSCALE MODEL CONFIRM THOSE AREAS THROUGH 10 AM THIS MORNING. RECENTLY THE GARDEN CITY AIRPORT WENT BACK UP TO 3 MILES AND FOG SO THE WESTERN EDGE LOOKS TO BE NEAR KGCK AT THIS TIME. THE FOG DUE TO MOIST ADVECTION AND RADIATIONAL COOLING AHEAD OF A LEE TROUGH IN EASTERN COLORADO. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 310 AM CDT SUN SEP 16 2012 THE MAIN FORECAST CHALLENGES ARE AREAS OF DENSE FOG THIS MORNING. LIGHT MOIST UPSLOPE FLOW AHEAD OF A LEE TROUGH THIS MORNING WILL CONTINUE TO ADVECT HIGHER DEWPOINTS WESTWARD INTO OUR WESTERN COUNTIES UNDER CLEAR SKIES. A WEAK WARM FRONT AND WIND SHIFT TO THE SOUTH BY 12Z FROM WAKEENEY SOUTH TO DODGE CITY AND ASHLAND MAY HOWEVER LIMIT DENSE FOG FORMATION WEST OF THAT LINE AS UPSLOPE ENDS. ALREADY PRATT SHOWING 2 MILES AND OVERCAST 100 FEET. NEW REPORTS UNDER 1/4 MILE AND FOG COMING IN FROM PRATT AND HAYS SO WILL GO AHEAD AND ISSUE A DENSE FOG ADVISORY FROM HAYS SOUTH TO GREENSBURG AND EAST TO PRATT THROUGH 10 AM. THE DENSE FOG SHOULD QUICKLY CLEAR BY MID MORNING AS LIGHT SOUTH WINDS CONTINUE AND WITH A VERY SHALLOW MOIST LAYER. A STRONG UPPER LEVEL SHORTWAVE TROUGH WILL DIG INTO THE NORTHERN HIGH PLAINS BY THIS EVENING AND THEN DIG INTO THE CENTRAL PLAINS BY MONDAY MORNING. THIS FEATURE WILL PUSH A STRONG COLD FRONT ACROSS WESTERN KANSAS BY EARLY MORNING WITH THE FRONT RUNNING FROM NEAR SAINT JOHN TO ASHLAND. SOUTH WINDS OVERNIGHT WILL SHIFT ABRUPTLY TO THE NORTH AT 20 TO 35 MPH AND GUSTY WITH THE COLD FRONT. ONLY SOME MID TO HIGH LEVEL CLOUDS ARE FORECAST WITH AND BEHIND THE COLD FRONT. HIGHS WILL BE WARMER WITH 850 TEMPS RISING TO AROUND 20C WITH A WEAK WARM FRONT AND RANGE FROM THE MID 80S TO UPPER 80S WEST TO LOW TO MID 80S EAST. OVERNIGHT LOWS WILL RANGE FROM THE UPPER 40S TO LOWER 50S WEST AND NORTH BEHIND THE COLD FRONT TO THE MID TO UPPER 50S IN OUR SOUTHEAST FA FROM SAINT JOHN TO ASHLAND AND EAST. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 310 AM CDT SUN SEP 16 2012 THE COLD FRONT EXPECTED MONDAY MORNING APPEARS THE HAVE A RELATIVELY TIGHT SURFACE PRESSURE GRADIENT OF AROUND 8 MB ACROSS WESTERN KANSAS. LARGE DIFFERENCES EXIST IN THE WIND SPEED OUTPUT BETWEEN THE GFS MOS - ECMWF AND NAM MODELS. IT IS PROBABLE THAT A FEW HOURS OF WIND ADVISORY CRITERIA WIND SPEEDS WILL BE MET. HOWEVER, GIVEN THE LACK LUSTER SPEEDS OF THE ECMWF AND EVEN THE MOS IN CENTRAL KANSAS, WE WILL HOLD OFF ON ANY ADVISORY ISSUING NOW AND DEFER TO CLOSER TO THE EVENT. IT DOES APPEAR TO BE SHAPING UP AS A TYPICAL MARGINAL OR LOW END WIND EPISODE. THE COOLER AIR USHERED IN WILL LIKELY TEMPER HIGHS ON MONDAY INTO THE UPPER 60S. SOUTH CENTRAL KANSAS WILL PROBABLY BE WARMER SINCE THE AREA WOULD REMAIN IN THE WARM SECTOR LONGER. THE DRY AIR LEFT IN THE WAKE OF THE FRONT SHOULD PROMOTE STRONG LONGWAVE RADIATIONAL COOLING OVERNIGHT, BUT THIS ALSO COULD BE MODIFIED SLIGHTLY BY MID TO UPPER LEVEL CLOUDS ASSOCIATED WITH THE STRONG UPPER JET MOVING THROUGH THE CENTRAL PLAINS. TEMPERATURES BY EARLY TUESDAY SHOULD FALL INTO THE LOW 40S ACROSS A BROAD AREA. NORTHWEST FLOW WILL PERSIST ALOFT ACROSS THE AREA. THE SURFACE RESPONSE WILL BE TO CREATE TROUGHING ACROSS EASTERN COLORADO, AND A WARMING TREND AS HIGHER TEMPERATURE BOUNDARY LAYER AIR OVERSPREADS SOUTHWEST KANSAS. WEDNESDAY CONTINUES TO LOOK LIKE THE WARMEST DAY WITH POTENTIAL FOR ADIABATICALLY WARMED AIR FROM DOWNSLOPE WINDS. THE REMAINDER OF THE EXTENDED PERIOD LOOKS TO REMAIN DRY WITH NEAR NORMAL TEMPERATURES FOR MID TO LATE SEPTEMBER. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1230 AM CDT SUN SEP 16 2012 LIGHT MOIST UPSLOPE FLOW CONTINUES AHEAD OF A LEE SIDE TROUGH INTO THIS MORNING. NEW HRRR MODEL UPDATE CONTINUES TO SHOW AREAS OF SHALLOW ADVECTION/RADIATION FOG DEVELOPING AFTER 09Z TILL AROUND 15Z AT THE TAF SITES THIS MORNING. HOWEVER NEW NAM SHOWING LIGHT UPSLOPE BECOMING LIGHT SOUTH BY 09-12Z FROM KGCK TO KDDC WITH NOT AS MUCH FOG. NEW RAP SHOWING POSSIBLE STRATUS AND DENSE FOG EAST OF A LINE FROM WAKEENEY TO DODGE CITY AND ASHLAND. WILL KEEP A TEMPO GROUP GOING FOR SOME IFR VSBYS BETWEEN 09-15Z FOR THE TAF SITES WITH RAPID CLEARING AFTER THAT. LIGHT SSE WINDS CONTINUE AHEAD OF A COLD FRONT FORECAST TO BE NEAR KGLD BY 06Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 84 50 68 42 / 0 0 10 10 GCK 86 49 68 42 / 0 0 10 0 EHA 87 50 68 47 / 0 0 20 10 LBL 86 49 69 44 / 0 0 20 10 HYS 85 49 69 42 / 0 10 20 10 P28 84 59 77 46 / 0 0 20 10 && .DDC WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR KSZ030-031- 044>046-063>066-077>081-087>090. && $$ UPDATE...KRUSE SHORT TERM...KRUSE LONG TERM...RUSSELL AVIATION...KRUSE
AREA FORECAST DISCUSSION
NWS GLASGOW MT
852 AM MDT SUN SEP 16 2012 .SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH TUESDAY... MORNING UPDATE... UPDATES THIS MORNING WERE LIGHT. BLENDED IN HRRR AND NAM5 FOR SLIGHTLY BETTER RESOLUTION ON WIND FIELDS. AFTER LOOKING OVER HEAVY CLOUD COVER AND VERY LIGHT RAIN ACROSS THE REGION DECREASED TEMPERATURES ACROSS THE FAR NORTHEAST A BIT. THERE ARE AN ABUNDANCE OF ECHOS SHOWING UP ON RADAR BUT RAIN GAGE SITES ARE NOT RECORDING MUCH AT THE MOMENT. CURRENTLY WAITING FOR THE BOUNDARY LAYER TO MOISTEN UP ENOUGH TO PRODUCE MORE THAN SPRINKLES. BUT THIS MAY TAKE A AWHILE TODAY AND THE LIFT MECHANISM MAY LEAVE THE AREA BY THE TIME RAIN CAN FINALLY HIT THE GROUND PREVENTING ANY SIZABLE QPF FROM ACTUALLY FORMING. GAH PREVIOUS SHORT TERM DISCUSSION... COLD FRONT CURRENTLY MOVING SOUTH ACROSS EASTERN MONTANA. THIS FRONT WILL CONTINUE TO MOVE SOUTH THIS MORNING BRINGING COLDER AIR INTO THE FORECAST AREA. SHORTWAVE TROUGH CURRENTLY MOVING THROUGH ALBERTA AND SASKATCHEWAN WILL SLIDE THROUGH NORTHEAST MONTANA THIS AFTERNOON AND EVENING. A FEW SHOWERS HAVE DEVELOPED OVERNIGHT ACROSS SOUTHERN SASKATCHEWAN AHEAD OF THIS TROUGH AND WILL AFFECT NORTHEAST MONTANA TODAY. WITH VERY DRY LOW LEVEL AIRMASS AT THE MOMENT...SOME OF THESE SHOWERS WILL EVAPORATE BEFORE REACHING THE GROUND RESULTING IN VIRGA. WILL GO WITH A MIX OF SLIGHT CHANCE AND LOW CHANCE POPS FOR TODAY. TEMPERATURES WILL BE NOTICEABLY COOLER WITH HIGHS IN THE 60S IN MOST AREAS AND UPPER 50S NORTH WITH NORTH TO NORTHEAST WINDS 10 TO 20 MPH. THE SHORTWAVE MOVES TO THE EAST TONIGHT ENDING THE CHANCE OF SHOWERS. NORTHWEST FLOW ALOFT WILL PREVAIL FOR MONDAY AND TUESDAY. A STRONG UPPER RIDGE WILL BUILD ON THE WEST COAST WHILE A LONGWAVE TROUGH DEVELOPS TO THE EAST. HIGH PRESSURE BUILDING INTO EASTERN MONTANA WILL DIMINISH THE WINDS AND CLEARING SKIES WILL ALLOW FOR A COOL NIGHT WITH SOME LOW LYING AREAS SEEING BELOW FREEZING TEMPERATURES. SURFACE HIGH ON MONDAY WILL BRING A MOSTLY SUNNY DAY WITH LIGHT WINDS AND SLIGHTLY WARMER TEMPERATURES. SHORTWAVE RIDGE IN NORTHWEST FLOW ALOFT WILL BRING WARMER TEMPERATURES ON TUESDAY. WEST TO NORTHWEST WINDS WILL INCREASE TUESDAY AFTERNOON AHEAD OF THE NEXT COLD FRONT TUESDAY NIGHT. WITH LOW RELATIVE HUMIDITY...CRITICAL FIRE WEATHER CONDITIONS ARE POSSIBLE. WILL HIGHLIGHT IN HAZARDOUS WEATHER OUTLOOK. FORRESTER .LONG TERM...TUESDAY NIGHT THROUGH SUNDAY... THE EXTENDED PERIOD BEGINNING TUESDAY NIGHT WILL BRING IN SEASONAL TEMPERATURES AND FEW CHANCES FOR RAIN. INITIALLY THERE WILL BE A RIDGE IN THE WEST AND NORTHWESTERLY FLOW ALOFT OVER NORTHEAST MONTANA. AN EMBEDDED SHORT WAVE TROUGH IN THE UPPER FLOW RIDING DOWN FROM CANADA TUESDAY NIGHT WILL SEND A DRY COLD FRONT OVER NEMONT. THIS WILL COOL TEMPERATURES FROM THE PREVIOUS DAY BY AROUND 10F DEGREES. THE COLD FRONT BECOMES STATIONARY...ORIENTATED NORTHWEST TO SOUTHEAST THROUGH NEMONT. THE SLIGHTLY FLUCTUATING BOUNDARY WILL STRADDLE NEMONT. BY THURSDAY THE RIDGE PEAK AMPLIFIES WELL INTO BRITISH COLUMBIA...CONTINUING THE NORTHWEST FLOW OVER MONTANA. BOTH THE GFS AND ECMWF BRING ANOTHER SHORT WAVE DISTURBANCE IN THE UPPER FLOW AROUND THURSDAY NIGHT. THERE IS A DIFFERENCE IN THE LONGITUDINAL POSITION OF THE COLD BOUNDARY DEPENDING ON MODEL. SO THERE IS SOME UNCERTAINTY. THE EAST-WEST ORIENTATION OF THE STATIONARY BOUNDARY WILL DETERMINE WHETHER TEMPERATURES REMAIN SEASONAL OR BECOME COOLER. THERE IS ALSO THE SLIGHT POSSIBILITY OF A LIMITED AMOUNT OF OVERRUNNING MOISTURE THAT COULD BRING SOME LIGHT RAIN INTO FRIDAY. SCT && .AVIATION... SKIES WILL BECOME INCREASINGLY CLOUDY AS A COLD FRONT PUSHES SOUTH FROM CANADA. ISOLATED TO SCATTERED RAIN SHOWERS CAN BE EXPECTED TODAY. SHOWERS COULD LINGER NEAR THE NORTH DAKOTA STATE BORDER INTO THIS EVENING BEFORE MOVING EAST. NORTHEAST WINDS TONIGHT OF AROUND 5 TO 15 KNOTS WILL BACK TO THE NORTH BEHIND THE COLD FRONT LATER THIS MORNING. SCT && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS RALEIGH NC
745 AM EDT SUN SEP 16 2012 .SYNOPSIS... A WEAK FRONT WILL HOLD NEAR THE NORTH CAROLINA AND SOUTH CAROLINA STATE LINE THROUGH TODAY... AS HIGH PRESSURE NOSES IN FROM THE NORTH. THE FRONT WILL RETURN AS A WARM FRONT LATE MONDAY INTO TUESDAY... WITH THE APPROACH OF A STRONG STORM SYSTEM FROM THE SOUTHWEST. && .NEAR TERM /TODAY THROUGH MONDAY NIGHT/... AS OF 745 AM SUNDAY... THROUGH THE MORNING: UPDATE ISSUED EARLIER TO ACCOUNT FOR A FAIRLY WIDE EXPANSE OF RAIN COVERING MUCH OF THE NORTHERN PIEDMONT. THIS APPEARS TO BE ASSOCIATED IN PART WITH A SMALL MID LEVEL WAVE EMBEDDED WITHIN THE BAND OF VORTICITY SHEARING ACROSS WRN AND NRN NC... CONCURRENT WITH WEAK LOW LEVEL MASS CONVERGENCE AND CONCENTRATED MOIST UPGLIDE. THE RISK OF SHALLOW BUT SLOW-MOVING AND POTENTIALLY HEAVY SHOWERS SHOULD PERSIST INTO THE MORNING WITH LITTLE CHANGE IN THE OVERALL REGIME... AS NOTED BY THE MOST RECENT SPC WRF-NMM AND SREF RAIN PROBABILITIES. THE EXISTING RAIN AREA WILL CONTINUE A SLOW DRIFT TO THE ENE... DEPARTING THE AREA BY LATE MORNING WHICH IS SUPPORTED BY THE HRRR OUTPUT... FOLLOWED BY A BRIEF LULL IN PRECIP CHANCES. WIDESPREAD CLOUDS ESPECIALLY IN THE NORTH WILL TEMPER HEATING... SO THE MORNING SHOULD BE COOLER THAN USUAL WITH ONLY A MINOR RISE THROUGH THE 60S IN MOST AREAS. EARLIER DISCUSSION FROM 210 AM... FOR THE REST OF TODAY AND TONIGHT: THE STRONG MID LEVEL LOW NOW OVER WEST TX AND ASSOCIATED POSITIVELY TILTED TROUGH THROUGH THE MID MISS VALLEY WILL EASE EASTWARD OVER THE NEXT COUPLE OF DAYS... AS NORTHERN STREAM TROUGHING DIGS STRONGLY INTO THE UPPER MIDWEST. A DIFFUSE SURFACE FRONTAL ZONE CURRENTLY SITS ALONG THE NC/SC STATE LINE EXTENDING BACK THROUGH WRN NC... BENEATH A BAND OF SHEARED VORTICITY IN THE MID LEVELS... WHILE THE SURFACE HIGH CENTERED NEAR THE OH/PA BORDER NOSES SOUTHWARD INTO NC. AS THE SURFACE HIGH SHIFTS OFF THE VA COAST THIS AFTERNOON... THE COMBINATION OF LOW LEVEL RETURN FLOW FROM THE SE... THE NORTHEAST-RETREATING FRONTAL ZONE... THE STEADILY RISING PRECIP WATER TO 150-175% OF NORMAL... INCREASING LOW LEVEL MOISTURE TRANSPORT... AND THE NNE-MOVING BAND OF MID LEVEL VORTICITY SHOULD ALL SUPPORT INCREASING CHANCES FOR SHOWERS AND STORMS MAINLY IN THE WRN HALF AND SRN PORTIONS OF THE CWA TODAY... DECREASING A BIT IN COVERAGE BUT SPREADING EASTWARD TONIGHT. INSTABILITY SHOULD REMAIN MARGINAL WITH 400-800 J/KG OF MLCAPE IN THE SRN/WRN PART OF THE FORECAST AREA THIS AFTERNOON... BUT DEEP LAYER SHEAR OF 30-35 KTS SHOULD ALLOW FOR SUSTAINED CONVECTION FOCUSED ALONG THE FRONTAL ZONE. THE PRIMARY THREAT WILL BE FROM LOCALLY HEAVY RAINFALL TOTALS GIVEN THE WEAK WINDS THROUGH THE LOWEST 3 KM. MAX TEMPS TODAY ARE TRICKY DUE TO THE WIDE VARIATION THIS MORNING... RANGING FROM MID 50S IN THE NORTHWEST BENEATH THE COOLER SURFACE RIDGE WITH VERY FEW CLOUDS... TO AROUND 70 IN PARTS OF THE SANDHILLS AND TRIAD AREA BENEATH THICK CLOUDS. THE COOLEST MAXES TODAY SHOULD OCCUR FROM THE TRIAD TO THE NORTHEAST WHERE THE MOIST UPGLIDE UP AND OVER THE FRONTAL ZONE SHOULD INDUCE THICK CLOUD COVER AND A FEW SHOWERS FALLING INTO THE RETREATING COOLER AIR MASS. HIGHS 72-74 NW TO 83 IN THE SE. THE MOIST UPGLIDE DEEPENS TO 290K-310K AND EXPANDS EASTWARD TONIGHT ACROSS THE REMAINDER OF CENTRAL NC... PARTICULARLY THE NORTH. WE RETAIN A FEW HUNDRED J/KG OF MLCAPE OVERNIGHT ACCORDING TO THE NAM/ECMWF... AND WITH DEEP LAYER SHEAR HOLDING AT 30-35 KTS... ISOLATED STORMS REMAIN POSSIBLE OVERNIGHT. WILL HOLD ONTO SCATTERED SHOWERS AND A FEW STORMS THROUGH THE NIGHT... WITH THE BEST COVERAGE ACROSS THE NORTH AND WEST. MODELS DO INDICATE A VORTICITY MAXIMUM EXITING INTO SE VA LATE AT NIGHT... AND WITH THE LACK OF OTHER UPPER FORCING INCLUDING AN IDEALLY-LOCATED JETLET TO OUR NORTH OR NE... WE MAY SEE A LULL IN ACTIVITY OVERNIGHT WITH JUST PATCHY SHOWERS. LOWS 60-66. FOR MONDAY/MONDAY NIGHT: RAIN CHANCES OVER THE WRN CWA SHOULD RAMP UPWARD QUICKLY HEADING INTO MONDAY NIGHT. THE SURFACE HIGH SHIFTS FURTHER OFFSHORE LEADING TO A RAPIDLY STRENGTHENING SOUTHERLY LOW LEVEL FLOW OF MOIST GULF AND ATLANTIC AIR INTO NC. THE SOUTHERN STREAM WAVE OVER EAST TN EARLY MONDAY DAMPENS AS IT HEADS EAST THROUGH THE LOWER MISS VALLEY... OVERTAKEN BY THE STRENGTHENING NORTHERN STREAM LONGWAVE TROUGH DIGGING THROUGH THE UPPER MIDWEST AND WRN GREAT LAKES. FORCING FOR ASCENT AT ALL LEVELS BEGINS TO INTENSIFY ESPECIALLY OVER WRN NC. THE STRENGTHENING SWRLY UPPER JET CORE OVER MI/ONTARIO WILL INDUCE BROAD STRONG UPPER DIVERGENCE FROM THE OHIO VALLEY THROUGH THE MID SOUTH TO THE GULF COAST INCLUDING WRN NC... AND AS THE 40-50 KT LOW LEVEL JET BECOMES MORE DEFINED OVER WRN NC... LOW LEVEL MASS CONVERGENCE ACTING ON PRECIP WATER VALUES APPROACHING 2.0 INCHES SHOULD SUPPORT NUMEROUS TO WIDESPREAD SHOWERS AND STORMS. INSTABILITY WANES A BIT WITH LOSS OF DAYTIME HEATING MONDAY EVENING BUT IS EXPECTED TO RISE ANEW IN THE WRN/SW CWA TO NEAR 500 J/KG (MLCAPE) MONDAY NIGHT WITH ABUNDANT LOWER TROPOSPHERIC WARM AIR ADVECTION. MAIN CHANGE TO EARLIER FORECAST PRECIP CHANCES WILL BE TO REDUCE OVERALL PRECIP CHANCES IN THE EAST AS THE BULK OF THE FORCING AND MOISTURE TRANSPORT WILL BE FOCUSED OVER WRN NC. WILL INDICATE A SLOW INCREASE IN POPS FROM CHANCE WEST / SLIGHT CHANCE OR NO POP EAST MONDAY MORNING... TRENDING UPWARD TO LIKELY THEN CATEGORICAL POPS IN THE FAR WRN CWA MONDAY AFTERNOON THROUGH NIGHT... WHILE KEEPING JUST A LOW CHANCE IN THE FAR EAST AWAY FROM THE LIFT SOURCES. TRAINING STORMS WILL YIELD A FLOODING THREAT IN THE FAR WRN PIEDMONT BACK TOWARD THE MOUNTAINS... INCLUDING THE TRIAD AND ALBEMARLE/WADESBORO REGIONS... LATE MONDAY THROUGH MONDAY NIGHT. HIGHS 76-83... WARMEST EAST. VERY MILD LOWS OF 65-70. -GIH && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... AS OF 315 AM SUNDAY... A SHORTWAVE TROUGH IS EXPECTED TO DEAMPLIFY AND LIFT NORTHEAST ALONG THE APPALACHIANS MONDAY NIGHT THROUGH TUESDAY NIGHT AHEAD OF A NORTHERN STREAM SYSTEM FORECAST TO DIG INTO THE MIDWEST STATES. DUE TO CONVECTIVE FEEDBACK ISSUES...THE GFS IS MOSTLY DISCOUNTED AT THIS TIME AND THE CURRENT FORECAST WILL RELY ON THE SLOWER ECMWF AND NAM SOLUTIONS. THE SURFACE COLD FRONT ASSOCIATED WITH THE NORTHERN STREAM TROUGH IS FORECAST TO STRETCH FROM NEAR TOLEDO TO NASHVILLE AT 12Z TUESDAY MORNING. THE STRONGEST SYNOPTIC SCALE LIFT WILL BE OVER WESTERN NC EARLY TUESDAY MORNING...WHERE BACK LOW LEVEL UPSLOPE FLOW AND A 40KT LOW LEVEL JET WILL BE COUPLED WITH STRENGTHENING UPPER LEVEL DIVERGENCE IN THE RIGHT ENTRANCE REGION OF AN JET OVER THE GREAT LAKES. THUS..WIDESPREAD SHOWERS ARE EXPECTED OVER THE FOOTHILLS AND WESTERN PIEDMONT...WITH ONLY ISOLATED TO SCATTERED SHOWERS FURTHER EAST OVER CENTRAL NC. PRECIP IS EXPECTED TO SPREAD EAST DURING THE DAY AS THE LOW LEVEL JET SHIFTS EASTWARD AND STRONG WARM SECTOR THETA E ADVECTION SURGES ACROSS THE CWA. THE CURRENT POP FORECAST OF 80-80 PERCENT IN THE WEST EARLY AND 70-80 PERCENT OVER THE EAST DURING THE AFTERNOON LOOKS GOOD AND NO SIGNIFICANT CHANGES WILL BE MADE. HIGHS TUESDAY SHOULD RANGE FROM THE MID 70S WEST TO LOWER 80S IN THE EAST....THOUGH CONFIDENCE SOMEWHAT LOW DUE TO THE POTENTIAL DIABATIC IMPACTS FROM CLOUD COVER AND PRECIP WHILE UNCERTAINTY REMAINS REGARDING THE SEVERE THREAT TUESDAY...THE SLOWING TREND IN THE MODELS SUPPORTS A MORE FAVORABLE DIURNAL TIMING...ESPECIALLY FOR PREFRONTAL CONVECTION. STRENGTHENING DEEP LAYER SHEAR ASSOCIATED WITH 60-90M HEIGHT FALLS OVER THE OHIO VALLEY REGION AND A 40-50KT LOW LEVEL JET WILL SUPPORT SUPERCELLAR ACTIVITY WHERE SUFFICIENT INSTABILITY CAN DEVELOP. LOW LEVEL SHEAR WILL STRONG...WITH MODELS SHOWING LONG AND CURVED HODOGRAPHS AND 0-1KM BULK SHEAR IN EXCESS OF 20-25KT. WHILE INSTABILITY REMAINS QUESTIONABLE...NEARLY ALL MODELS SHOW DEWPOINTS CLIMBING INTO THE UPPER 60S TO AROUND 70S IN THE SOUTHEAST...AND WARM/THETA E ADVECTION WILL HELP TO OVERCOME WIDESPREAD CLOUD COVER AND WEAK MID LEVEL LAPSE RATES. SREF PLUMES POINT TOWARD 500-1000 J/KG OF SBCAPE ACROSS CENTRAL NC....WHICH COULD BE GREATER IF BREAKS IN CLOUD COVER DEVELOP. OUTSIDE OF WARM ADVECTION AND/OR A WEAK DISTURBANCE IN THE SOUTHWESTERLY FLOW ALOFT...THERE IS ALSO SOME UNCERTAINTY REGARDING THE EXTENT OF PREFRONTAL FORCING...AND THUS THE COVERAGE AND TIMING OF PREFRONTAL CONVECTION. HOWEVER...SEVERE WIND/TORNADO THREAT STILL REMAINS A CONCERN MAY DEVELOP BASED ON THE ABOVE KINEMATICS AND INSTABILITY. STRONGER DEEP LAYER FORCING IS EXPECTED TO REACH THE WESTERN CWA BY 00Z TUESDAY AFTERNOON/EVENING AS THE THE COLD FRONT AND MID LEVEL TROUGH AXIS CROSS THE MOUNTAINS. THIS WILL PUSH THE REMAINING SHOWERS/STORMS EASTWARD ACROSS THE AREA...WITH MODELS SHOWING PRECIP EXITING THE EASTERN CWA BY 09-12Z. WHILE MODELS HAVE SHOWN SIGNS OF A WEAK LOW DEVELOPING ALONG THE FRONT...THE THREAT OF SEVERE WEATHER SHOULD BECOME MORE OF A STRAIGHT LINE WIND THREAT AS WIND PROFILES BECOME INCREASINGLY UNIDIRECTIONAL TUESDAY EVENING. LOWS TUESDAY NIGHT WILL DEPEND ON THE TIMING OF THE FRONT AND QUICKLY PRECIP COMES TO AN END...BUT GUIDANCE MOSTLY AGREES ON MID 50S WEST TO MID 60S EAST. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 315 AM SUNDAY... QUIETER WEATHER IS EXPECTED WEDNESDAY THROUGH THE END OF THE WEEK. THE MEAN UPPER LEVEL TROUGH AXIS IS FORECAST TO LAG BACK TO THE WEST FROM THE MIDWEST TO THE DEEP SOUTH...BUT MORE STABLE AIR AND HIGH PRESSURE WILL BUILD ACROSS TN VALLEY AND INTO CENTRAL NC IN THE WAKE OF THE STORM SYSTEM DEPARTING THE REGION WEDNESDAY MORNING. MODELS HAVE BEEN SHOWING A SLOWING TREND WITH THE FRONTAL PASSAGE TUESDAY NIGHT INTO WEDNESDAY...SO IT IS POSSIBLE THAT FRONT MAY STALL NEAR OR JUST OFFSHORE. LOW LEVEL THICKNESSES ARE FORECAST TO DIP INTO THE 1360S...KEEPING HIGHS WEDNESDAY AND THURSDAY ABOUT A CATEGORY BELOW NORMAL...73-78. A SLOW MODERATION IS THEN EXPECTED FOR THE REMAINDER OF THE WEEK HIGHS CLIMBING BACK TOWARD THE UPPER 70S AND LOWER 80S. A SHORTWAVE IS FORECAST TO SWING ACROSS THE NORTHERN US AND GREAT LAKES REGION OVER THE WEEKEND...WHICH MAY SEND ANOTHER COLD FRONT ACROSS THE MIDWEST STATES AND TOWARD THE APPALACHIANS. HOWEVER.. THERE IS ENOUGH DISAGREEMENT IN THE MEDIUM RANGE MODELS TO NOT SHOW ANY SENSIBLE IMPACTS IN THE FORECAST. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... AS OF 745 AM SUNDAY... VFR CIGS/VSBYS WILL DOMINATE OVER MUCH OF CENTRAL NC THROUGH THE DAYLIGHT HOURS... BUT A MAJOR EXCEPTION TO THIS IS THE MVFR FOG AND MVFR-IFR CIGS AT KINT/KGSO THIS MORNING. A WEAK FRONTAL ZONE EXTENDING ACROSS WRN AND SRN NC EARLY THIS MORNING WILL SLOWLY SHIFT TO THE NNE TODAY INTO TONIGHT... AS INCREASING SOUTHWESTERLY FLOW JUST ABOVE THE GROUND PUMPS INCREASING MOISTURE INTO THE REGION. CLOUDS WILL CONTINUE TO SLOWLY THICKEN WITH LOWERING BASES AT KRDU/KFAY/KRWI THROUGH THIS AFTERNOON AND NIGHT. AT KINT/KGSO... AFFECTED THROUGH MUCH OF THE PREDAWN HOURS BY RAIN... WILL SEE THE MVFR TO IFR CIGS HOLD FOR MUCH OF THE MORNING BEFORE LIFTING TO VFR BY EARLY AFTERNOON... BY 17-19Z. CIGS ARE LIKELY TO GRADUALLY DROP TO MVFR LATE THIS AFTERNOON THROUGH THE EVENING... AS PATCHY RAIN MOVES INTO THE REGION. EXPECT CIGS/VSBYS TO DROP TO MVFR AND POTENTIALLY IFR AFTER 06Z TONIGHT. LOOKING BEYOND 12Z MONDAY MORNING... MVFR CIGS NEAR DAYBREAK SHOULD LIFT TO VFR BY MIDDAY MONDAY. CIGS WILL ONCE AGAIN SLOWLY LOWER TO MVFR FROM WEST TO EAST LATE MONDAY ONWARD AS A POWERFUL STORM SYSTEM -- A DEEPENING MID LEVEL TROUGH OVER THE MISS VALLEY AND ACCOMPANYING STRONG COLD FRONT -- APPROACHES NC FROM THE WEST. THE RISK OF ADVERSE AVIATION CONDITIONS WILL BE GREATEST STARTING MONDAY EVENING WITH LOWERING CIGS/VSBYS AND WIDESPREAD SHOWERS AND STORMS OVERSPREADING THE AREA. LOW LEVEL WIND SHEAR IS POSSIBLE ESPECIALLY MONDAY NIGHT INTO TUESDAY WHEN WINDS WILL INCREASE TO 35-50 KTS FROM THE SSW THROUGH THE LOWEST 10 THOUSAND FT AGL. AVIATION CONDITIONS WILL IMPROVE WEDNESDAY AS THE COLD FRONT SWEEPS THROUGH. GENERALLY VFR CONDITIONS ARE EXPECTED LATE WEDNESDAY TO THURSDAY. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...SMITH LONG TERM...SMITH AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1245 PM CDT SUN SEP 16 2012 ...UPDATED FOR THE 18Z TAF AND AVIATION DISCUSSION... .SYNOPSIS... ISSUED AT 1230 PM CDT SUN SEP 16 2012 A WEAK UPPER LEVEL CYCLONE WAS EVIDENT OVER SOUTHWEST TEXAS WITH A TROUGH EXTENDING INTO SOUTHEAST MISSOURI THIS MORNING. A WEAK SURFACE HIGH PRESSURE SYSTEM WAS CENTERED IN WEST VIRGINIA WITH A RIDGE EXTENDING ACROSS THE SOUTHERN PLAINS INTO SOUTH TEXAS. A MOIST, STAGNANT AIR MASS COVERED MUCH OF THE SOUTHERN AND CENTRAL PLAINS, AND WIDESPREAD LOW CLOUDINESS WAS EVIDENT EAST OF A LINE FROM SAN ANGELO TO CENTRAL KANSAS LATE THIS MORNING. FOG WAS EXTENSIVE IN CENTRAL AND WESTERN KANSAS EARLY IN THE DAY BUT ERODED BY MID MORNING. THE MID LEVELS OF THE ATMOSPHERE WERE QUITE WARM IN THE CENTRAL PLAINS WITH H7 TEMPERATURES NEAR 10C OVER WESTERN KANSAS. A PLUME OF LOW LEVEL WARM AIR COVERED EASTERN COLORADO AND SOUTHWEST NEBRASKA WITH H8 TEMPERATURES IN EXCESS OF 20C. A DEEP CYCLONE WAS CENTERED NEAR THE SOUTHWEST COAST OF ALASKA THIS MORNING, AND STRONG WARM AIR ADVECTION WAS ENHANCING UPPER LEVEL RIDGING IN ALASKA AND WESTERN CANADA AND AMPLIFICATION OF THE DOWNSTREAM LONG WAVE TROUGH EVOLVING IN THE MISSISSIPPI VALLEY. A STRONG UPPER LEVEL JET WITH H25 WINDS IN EXCESS OF 140 KNOTS WAS EVIDENT IN ADVANCE OF THE ALASKAN UPPER LEVEL CYCLONE, AND A JET STREAK WITH WINDS EXCEEDING 130 KNOTS EXTENDED FROM THE NORTHWEST TERRITORIES INTO SASKATCHEWAN. A VIGOROUS UPPER LEVEL TROUGH EXTENDED FROM AN UPPER LEVEL LOW NEAR THE NORTH SHORE OF HUDSON BAY INTO SOUTHERN SASKATCHEWAN, AND A DEEP SURFACE CYCLONE WAS OVER THE NORTHERN PART OF HUDSON BAY. A COLD FRONT WAS EXTENDED FROM THE HUDSON BAY LOW ACROSS CENTRAL MANITOBA TO NEAR THE NORTHERN NEBRASKA BORDER THEN BACK INTO ALBERTA ALONG THE HIGHER TERRAIN. TEMPERATURES BEHIND THE COLD FRONT AT 16Z WERE COOL WITH READINGS IN THE LOWER 50S FROM NORTH DAKOTA INTO THE PRAIRIE PROVINCES. AN UPPER LEVEL TROUGH WAS EVIDENT IN A DEFORMATION ZONE OVER OREGON, AND A PLUME OF HIGH LEVEL TROPICAL MOISTURE WAS FLOWING FROM THE DEEP TROPICS INTO NORTHERN CALIFORNIA ON THE EAST SIDE OF AN UPPER LEVEL CYCLONE CENTERED NEAR 138W/34N. ANOTHER JET STREAK WAS EVIDENT IN MORNING RAOBS FROM NORTHERN CALIFORNIA TO WESTERN UTAH. && .UPDATE... ISSUED AT 955 AM CDT SUN SEP 16 2012 UPDATED THE FORECAST FOR MAINLY MAX TEMPS TODAY, LOWERING THEM A BIT IN MY EASTERN ZONES. DENSE FOG THIS MORNING AND LINGERING LOWER CLOUDS THROUGH NOON TO 1 PM CDT WILL SLOW DOWN DAY TIME HEATING. ALSO, THE HRRR, RUC AND NAM MODELS ALL HAVE UPPER 70S FOR HIGH IN THE LARNED AND PRATT AREAS. BUMPED HIGHS DOWN IN THE JETMORE, DODGE CITY AND ASHLAND AREAS TO LOWER 80S. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 310 AM CDT SUN SEP 16 2012 THE MAIN FORECAST CHALLENGES ARE AREAS OF DENSE FOG THIS MORNING. LIGHT MOIST UPSLOPE FLOW AHEAD OF A LEE TROUGH THIS MORNING WILL CONTINUE TO ADVECT HIGHER DEWPOINTS WESTWARD INTO OUR WESTERN COUNTIES UNDER CLEAR SKIES. A WEAK WARM FRONT AND WIND SHIFT TO THE SOUTH BY 12Z FROM WAKEENEY SOUTH TO DODGE CITY AND ASHLAND MAY HOWEVER LIMIT DENSE FOG FORMATION WEST OF THAT LINE AS UPSLOPE ENDS. ALREADY PRATT SHOWING 2 MILES AND OVERCAST 100 FEET. NEW REPORTS UNDER 1/4 MILE AND FOG COMING IN FROM PRATT AND HAYS SO WILL GO AHEAD AND ISSUE A DENSE FOG ADVISORY FROM HAYS SOUTH TO GREENSBURG AND EAST TO PRATT THROUGH 10 AM. THE DENSE FOG SHOULD QUICKLY CLEAR BY MID MORNING AS LIGHT SOUTH WINDS CONTINUE AND WITH A VERY SHALLOW MOIST LAYER. A STRONG UPPER LEVEL SHORTWAVE TROUGH WILL DIG INTO THE NORTHERN HIGH PLAINS BY THIS EVENING AND THEN DIG INTO THE CENTRAL PLAINS BY MONDAY MORNING. THIS FEATURE WILL PUSH A STRONG COLD FRONT ACROSS WESTERN KANSAS BY EARLY MORNING WITH THE FRONT RUNNING FROM NEAR SAINT JOHN TO ASHLAND. SOUTH WINDS OVERNIGHT WILL SHIFT ABRUPTLY TO THE NORTH AT 20 TO 35 MPH AND GUSTY WITH THE COLD FRONT. ONLY SOME MID TO HIGH LEVEL CLOUDS ARE FORECAST WITH AND BEHIND THE COLD FRONT. HIGHS WILL BE WARMER WITH 850 TEMPS RISING TO AROUND 20C WITH A WEAK WARM FRONT AND RANGE FROM THE MID 80S TO UPPER 80S WEST TO LOW TO MID 80S EAST. OVERNIGHT LOWS WILL RANGE FROM THE UPPER 40S TO LOWER 50S WEST AND NORTH BEHIND THE COLD FRONT TO THE MID TO UPPER 50S IN OUR SOUTHEAST FA FROM SAINT JOHN TO ASHLAND AND EAST. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 310 AM CDT SUN SEP 16 2012 THE COLD FRONT EXPECTED MONDAY MORNING APPEARS THE HAVE A RELATIVELY TIGHT SURFACE PRESSURE GRADIENT OF AROUND 8 MB ACROSS WESTERN KANSAS. LARGE DIFFERENCES EXIST IN THE WIND SPEED OUTPUT BETWEEN THE GFS MOS - ECMWF AND NAM MODELS. IT IS PROBABLE THAT A FEW HOURS OF WIND ADVISORY CRITERIA WIND SPEEDS WILL BE MET. HOWEVER, GIVEN THE LACK LUSTER SPEEDS OF THE ECMWF AND EVEN THE MOS IN CENTRAL KANSAS, WE WILL HOLD OFF ON ANY ADVISORY ISSUING NOW AND DEFER TO CLOSER TO THE EVENT. IT DOES APPEAR TO BE SHAPING UP AS A TYPICAL MARGINAL OR LOW END WIND EPISODE. THE COOLER AIR USHERED IN WILL LIKELY TEMPER HIGHS ON MONDAY INTO THE UPPER 60S. SOUTH CENTRAL KANSAS WILL PROBABLY BE WARMER SINCE THE AREA WOULD REMAIN IN THE WARM SECTOR LONGER. THE DRY AIR LEFT IN THE WAKE OF THE FRONT SHOULD PROMOTE STRONG LONGWAVE RADIATIONAL COOLING OVERNIGHT, BUT THIS ALSO COULD BE MODIFIED SLIGHTLY BY MID TO UPPER LEVEL CLOUDS ASSOCIATED WITH THE STRONG UPPER JET MOVING THROUGH THE CENTRAL PLAINS. TEMPERATURES BY EARLY TUESDAY SHOULD FALL INTO THE LOW 40S ACROSS A BROAD AREA. NORTHWEST FLOW WILL PERSIST ALOFT ACROSS THE AREA. THE SURFACE RESPONSE WILL BE TO CREATE TROUGHING ACROSS EASTERN COLORADO, AND A WARMING TREND AS HIGHER TEMPERATURE BOUNDARY LAYER AIR OVERSPREADS SOUTHWEST KANSAS. WEDNESDAY CONTINUES TO LOOK LIKE THE WARMEST DAY WITH POTENTIAL FOR ADIABATICALLY WARMED AIR FROM DOWNSLOPE WINDS. THE REMAINDER OF THE EXTENDED PERIOD LOOKS TO REMAIN DRY WITH NEAR NORMAL TEMPERATURES FOR MID TO LATE SEPTEMBER. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1240 PM CDT SUN SEP 16 2012 AFTER THE STRATOCU CLOUDS AND DENSE FOG LIFTED THIS MORNING BETWEEN 15 AND 16Z, HIGH PRESSURE STARTED BUILDING, BRINGING CLEAR SKIES WITH BRIGHT SUNSHINE, AND SOUTH WINDS OF 10 TO 15 KTS. A STRONG COLD FRONT WILL BARREL SOUTHWARD EARLY MONDAY MORNING, SHIFTING WINDS ABRUPTLY TO THE NORTH AND QUICKLY INCREASING TO 20G30KTS. MID LEVEL CLOUDS ARE ALSO EXPECTED ALONG AND BEHIND THE FRONT, AND SHOULD BE IN THE 150-180 THOUSAND FOOT RANGE. THE MAY BE SOME LOW LEVEL WIND SHEAR MONDAY MORNING, BUT VERY BRIEFLY AS THE FRONT WILL BE TRAVELING TO THE SOUTH RAPIDLY. && .PRELIMINARY POINT TEMPS/POPS... DDC 82 50 68 42 / 0 0 10 10 GCK 85 49 68 42 / 0 0 10 0 EHA 87 50 68 47 / 0 0 20 10 LBL 86 49 69 44 / 0 0 20 10 HYS 80 49 69 42 / 0 10 20 10 P28 82 59 77 46 / 0 0 20 10 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...BURKE SYNOPSIS...RUTHI SHORT TERM...KRUSE LONG TERM...RUSSELL AVIATION...BURKE
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1232 PM CDT SUN SEP 16 2012 ...SYNOPSIS UPDATED AT 1730Z... .SYNOPSIS... ISSUED AT 1230 PM CDT SUN SEP 16 2012 A WEAK UPPER LEVEL CYCLONE WAS EVIDENT OVER SOUTHWEST TEXAS WITH A TROUGH EXTENDING INTO SOUTHEAST MISSOURI THIS MORNING. A WEAK SURFACE HIGH PRESSURE SYSTEM WAS CENTERED IN WEST VIRGINIA WITH A RIDGE EXTENDING ACROSS THE SOUTHERN PLAINS INTO SOUTH TEXAS. A MOIST, STAGNANT AIR MASS COVERED MUCH OF THE SOUTHERN AND CENTRAL PLAINS, AND WIDESPREAD LOW CLOUDINESS WAS EVIDENT EAST OF A LINE FROM SAN ANGELO TO CENTRAL KANSAS LATE THIS MORNING. FOG WAS EXTENSIVE IN CENTRAL AND WESTERN KANSAS EARLY IN THE DAY BUT ERODED BY MID MORNING. THE MID LEVELS OF THE ATMOSPHERE WERE QUITE WARM IN THE CENTRAL PLAINS WITH H7 TEMPERATURES NEAR 10C OVER WESTERN KANSAS. A PLUME OF LOW LEVEL WARM AIR COVERED EASTERN COLORADO AND SOUTHWEST NEBRASKA WITH H8 TEMPERATURES IN EXCESS OF 20C. A DEEP CYCLONE WAS CENTERED NEAR THE SOUTHWEST COAST OF ALASKA THIS MORNING, AND STRONG WARM AIR ADVECTION WAS ENHANCING UPPER LEVEL RIDGING IN ALASKA AND WESTERN CANADA AND AMPLIFICATION OF THE DOWNSTREAM LONG WAVE TROUGH EVOLVING IN THE MISSISSIPPI VALLEY. A STRONG UPPER LEVEL JET WITH H25 WINDS IN EXCESS OF 140 KNOTS WAS EVIDENT IN ADVANCE OF THE ALASKAN UPPER LEVEL CYCLONE, AND A JET STREAK WITH WINDS EXCEEDING 130 KNOTS EXTENDED FROM THE NORTHWEST TERRITORIES INTO SASKATCHEWAN. A VIGOROUS UPPER LEVEL TROUGH EXTENDED FROM AN UPPER LEVEL LOW NEAR THE NORTH SHORE OF HUDSON BAY INTO SOUTHERN SASKATCHEWAN, AND A DEEP SURFACE CYCLONE WAS OVER THE NORTHERN PART OF HUDSON BAY. A COLD FRONT WAS EXTENDED FROM THE HUDSON BAY LOW ACROSS CENTRAL MANITOBA TO NEAR THE NORTHERN NEBRASKA BORDER THEN BACK INTO ALBERTA ALONG THE HIGHER TERRAIN. TEMPERATURES BEHIND THE COLD FRONT AT 16Z WERE COOL WITH READINGS IN THE LOWER 50S FROM NORTH DAKOTA INTO THE PRAIRIE PROVINCES. AN UPPER LEVEL TROUGH WAS EVIDENT IN A DEFORMATION ZONE OVER OREGON, AND A PLUME OF HIGH LEVEL TROPICAL MOISTURE WAS FLOWING FROM THE DEEP TROPICS INTO NORTHERN CALIFORNIA ON THE EAST SIDE OF AN UPPER LEVEL CYCLONE CENTERED NEAR 138W/34N. ANOTHER JET STREAK WAS EVIDENT IN MORNING RAOBS FROM NORTHERN CALIFORNIA TO WESTERN UTAH. && .UPDATE... ISSUED AT 955 AM CDT SUN SEP 16 2012 UPDATED THE FORECAST FOR MAINLY MAX TEMPS TODAY, LOWERING THEM A BIT IN MY EASTERN ZONES. DENSE FOG THIS MORNING AND LINGERING LOWER CLOUDS THROUGH NOON TO 1 PM CDT WILL SLOW DOWN DAY TIME HEATING. ALSO, THE HRRR, RUC AND NAM MODELS ALL HAVE UPPER 70S FOR HIGH IN THE LARNED AND PRATT AREAS. BUMPED HIGHS DOWN IN THE JETMORE, DODGE CITY AND ASHLAND AREAS TO LOWER 80S. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 310 AM CDT SUN SEP 16 2012 THE MAIN FORECAST CHALLENGES ARE AREAS OF DENSE FOG THIS MORNING. LIGHT MOIST UPSLOPE FLOW AHEAD OF A LEE TROUGH THIS MORNING WILL CONTINUE TO ADVECT HIGHER DEWPOINTS WESTWARD INTO OUR WESTERN COUNTIES UNDER CLEAR SKIES. A WEAK WARM FRONT AND WIND SHIFT TO THE SOUTH BY 12Z FROM WAKEENEY SOUTH TO DODGE CITY AND ASHLAND MAY HOWEVER LIMIT DENSE FOG FORMATION WEST OF THAT LINE AS UPSLOPE ENDS. ALREADY PRATT SHOWING 2 MILES AND OVERCAST 100 FEET. NEW REPORTS UNDER 1/4 MILE AND FOG COMING IN FROM PRATT AND HAYS SO WILL GO AHEAD AND ISSUE A DENSE FOG ADVISORY FROM HAYS SOUTH TO GREENSBURG AND EAST TO PRATT THROUGH 10 AM. THE DENSE FOG SHOULD QUICKLY CLEAR BY MID MORNING AS LIGHT SOUTH WINDS CONTINUE AND WITH A VERY SHALLOW MOIST LAYER. A STRONG UPPER LEVEL SHORTWAVE TROUGH WILL DIG INTO THE NORTHERN HIGH PLAINS BY THIS EVENING AND THEN DIG INTO THE CENTRAL PLAINS BY MONDAY MORNING. THIS FEATURE WILL PUSH A STRONG COLD FRONT ACROSS WESTERN KANSAS BY EARLY MORNING WITH THE FRONT RUNNING FROM NEAR SAINT JOHN TO ASHLAND. SOUTH WINDS OVERNIGHT WILL SHIFT ABRUPTLY TO THE NORTH AT 20 TO 35 MPH AND GUSTY WITH THE COLD FRONT. ONLY SOME MID TO HIGH LEVEL CLOUDS ARE FORECAST WITH AND BEHIND THE COLD FRONT. HIGHS WILL BE WARMER WITH 850 TEMPS RISING TO AROUND 20C WITH A WEAK WARM FRONT AND RANGE FROM THE MID 80S TO UPPER 80S WEST TO LOW TO MID 80S EAST. OVERNIGHT LOWS WILL RANGE FROM THE UPPER 40S TO LOWER 50S WEST AND NORTH BEHIND THE COLD FRONT TO THE MID TO UPPER 50S IN OUR SOUTHEAST FA FROM SAINT JOHN TO ASHLAND AND EAST. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 310 AM CDT SUN SEP 16 2012 THE COLD FRONT EXPECTED MONDAY MORNING APPEARS THE HAVE A RELATIVELY TIGHT SURFACE PRESSURE GRADIENT OF AROUND 8 MB ACROSS WESTERN KANSAS. LARGE DIFFERENCES EXIST IN THE WIND SPEED OUTPUT BETWEEN THE GFS MOS - ECMWF AND NAM MODELS. IT IS PROBABLE THAT A FEW HOURS OF WIND ADVISORY CRITERIA WIND SPEEDS WILL BE MET. HOWEVER, GIVEN THE LACK LUSTER SPEEDS OF THE ECMWF AND EVEN THE MOS IN CENTRAL KANSAS, WE WILL HOLD OFF ON ANY ADVISORY ISSUING NOW AND DEFER TO CLOSER TO THE EVENT. IT DOES APPEAR TO BE SHAPING UP AS A TYPICAL MARGINAL OR LOW END WIND EPISODE. THE COOLER AIR USHERED IN WILL LIKELY TEMPER HIGHS ON MONDAY INTO THE UPPER 60S. SOUTH CENTRAL KANSAS WILL PROBABLY BE WARMER SINCE THE AREA WOULD REMAIN IN THE WARM SECTOR LONGER. THE DRY AIR LEFT IN THE WAKE OF THE FRONT SHOULD PROMOTE STRONG LONGWAVE RADIATIONAL COOLING OVERNIGHT, BUT THIS ALSO COULD BE MODIFIED SLIGHTLY BY MID TO UPPER LEVEL CLOUDS ASSOCIATED WITH THE STRONG UPPER JET MOVING THROUGH THE CENTRAL PLAINS. TEMPERATURES BY EARLY TUESDAY SHOULD FALL INTO THE LOW 40S ACROSS A BROAD AREA. NORTHWEST FLOW WILL PERSIST ALOFT ACROSS THE AREA. THE SURFACE RESPONSE WILL BE TO CREATE TROUGHING ACROSS EASTERN COLORADO, AND A WARMING TREND AS HIGHER TEMPERATURE BOUNDARY LAYER AIR OVERSPREADS SOUTHWEST KANSAS. WEDNESDAY CONTINUES TO LOOK LIKE THE WARMEST DAY WITH POTENTIAL FOR ADIABATICALLY WARMED AIR FROM DOWNSLOPE WINDS. THE REMAINDER OF THE EXTENDED PERIOD LOOKS TO REMAIN DRY WITH NEAR NORMAL TEMPERATURES FOR MID TO LATE SEPTEMBER. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 627 AM CDT SUN SEP 16 2012 MOIST ADVECTION AND RADIATIONAL COOLING AHEAD OF A LEE SIDE TROUGH IN EASTERN COLORADO HAS LED TO AREAS OF SHALLOW DENSE FOG WITH VLIFR TO LIFR CONDITIONS. AS THE SUN COMES UP THE DENSE FOG IS EXPECTED TO BURN OFF RAPIDLY BY AROUND 15Z WITH VFR CONDITIONS. A NORTHERN BRANCH SHORTWAVE TROUGH IS FORECAST TO DIG INTO THE CENTRAL PLAINS TONIGHT PUSHING A STRONG COLD FRONT ACROSS THE TAF SITES WITH LIGHT SOUTH WINDS SHIFTING TO THE NORTH AT 20-35KT. THE COLD FRONT IS FORECAST TO BE NEAR KHYS BY AROUND 09Z, KGCK BY 10Z, AND KDDC BY AROUND 11Z MONDAY MORNING. && .PRELIMINARY POINT TEMPS/POPS... DDC 82 50 68 42 / 0 0 10 10 GCK 85 49 68 42 / 0 0 10 0 EHA 87 50 68 47 / 0 0 20 10 LBL 86 49 69 44 / 0 0 20 10 HYS 80 49 69 42 / 0 10 20 10 P28 82 59 77 46 / 0 0 20 10 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...BURKE SYNOPSIS...RUTHI SHORT TERM...KRUSE LONG TERM...RUSSELL AVIATION...KRUSE
AREA FORECAST DISCUSSION
NWS PADUCAH KY
308 PM CDT SUN SEP 16 2012 .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... ISSUED 308 PM CDT SUN SEP 16 2012 THE WEAK SYSTEM RESPONSIBLE FOR THE SHOWERS LAST NIGHT AND EARLY THIS MORNING DISSIPATED AS IT MOVED EAST TODAY. IN ITS WAKE...SOME PARTIAL CLEARING DEVELOPED ACROSS THE LOWER OHIO VALLEY. WITH THE SOLAR HEATING...A FEW ISOLATED SHOWERS POPPED UP NEAR KPOF THIS AFTERNOON. OF MORE SIGNIFICANCE IS A LARGER AREA OF SHOWERS AND EVEN A FEW THUNDERSTORMS ALONG AND SOUTH OF INTERSTATE 40 AS OF 19Z. THE MAJORITY OF THE MODELS BRING THIS AREA NORTHWARD INTO SE MISSOURI AND SW KENTUCKY TONIGHT...AND EVENTUALLY UP INTO THE EVV AREA SOMETIME LATE TONIGHT OR MONDAY MORNING. THE PRIMARY EXCEPTION IS THE SREF...WHICH TENDS TO SUPPRESS THE SOUTHERN STREAM SHORTWAVE AND ITS ASSOCIATED QPF TO OUR SOUTH. THE 15Z RUC MODEL WAS RATHER AGGRESSIVE BRINGING MOISTURE NORTH FROM ARKANSAS...AND THIS WILL BE THE BASIS FOR THROWING OUT THE SREF. THE RATHER STRONG 500 MB SHORTWAVE OVER TEXAS WILL MOVE EAST NORTHEAST TONIGHT...BACKING OUR MID LEVEL WINDS INTO THE SOUTHWEST. THIS WILL OPEN THE DOOR FOR A SERIES OF VORT CENTERS THAT WILL MOVE NORTHEAST INTO THE OHIO VALLEY OVERNIGHT AND MONDAY. DEEP LAYER SOUTHERLY FLOW WILL BRING A SURGE OF HIGHER PW AIR NORTHWARD...WITH PW VALUES CLIMBING ABOVE 1.5 INCHES BY MONDAY. POPS WILL RISE INTO THE LIKELY CATEGORY OVERNIGHT ACROSS FAR SOUTHERN PORTIONS OF THE FA...WITH CHANCE POPS ELSEWHERE. LIKELY POPS WILL SPREAD NORTH AND EAST MONDAY ACROSS MOST OF WESTERN KY AND SW INDIANA. A STRONG COLD FRONT WILL SWING SOUTHEAST ACROSS THE LOWER OHIO VALLEY ON MONDAY NIGHT. AS THIS COLD FRONT ENCOUNTERS MOISTURE ASSOCIATED WITH THE SOUTHERN STREAM SHORTWAVE...NUMEROUS SHOWERS AND SOME ISOLATED THUNDER WILL PERSIST ACROSS MUCH OF OUR REGION. WHILE STORM TOTAL QPF IS GENERALLY UNDER AN INCH...THERE COULD BE SOME ISOLATED HEAVIER AMOUNTS. HEAVIEST TOTALS WILL BE IN KHOP AREA. DUE TO WIDESPREAD CLOUDS AND WEAK WIND FIELDS...CONVECTIVE DEVELOPMENT SHOULD BE LIMITED IN COVERAGE AND INTENSITY. ONCE THE COLD FRONT PASSES MONDAY NIGHT...WINDS WILL INCREASE FROM THE NORTHWEST. 850 MB WINDS WILL BE AVERAGING 25 TO 30 KNOTS TUESDAY. SURFACE WIND GUSTS MAY REACH 30 MPH WITH STRONG MIXING ON TUESDAY. STRONG DRYING BEHIND THE FRONT WILL RESULT IN RAPID CLEARING ON TUESDAY MORNING...BUT 850 MB TEMPS WILL BE FALLING QUICKLY INTO THE SINGLE DIGITS. THEREFORE...HIGHS WILL NOT GET OUT OF THE 60S DESPITE A FAIRLY MILD START TO THE DAY IN THE 50S. TUESDAY NIGHT WILL BE CHILLY AS A SURFACE RIDGE PASSES OVER THE OHIO VALLEY. CLEAR SKIES AND NEARLY CALM WINDS WILL BE FAVORABLE FOR STRONG RADIATIONAL COOLING. MOS GUIDANCE IS OFTEN TOO HIGH IN SUCH CASES...AND FORECAST WILL BE WEIGHTED TOWARD THE COOLER 2M NAM TEMPS. THIS YIELDS UPPER 30S IN MANY PLACES...WHICH SUGGESTS THE POSSIBILITY OF SOME PATCHY FROST. .LONG TERM /WEDNESDAY THROUGH SUNDAY/... ISSUED 308 PM CDT SUN SEP 16 2012 TROUGHING ALOFT OVER THE WESTERN GREAT LAKES TO BEGIN THE PERIOD IS EXPECTED TO AMPLIFY AND DEVELOP SOUTHWARD TOWARD THE LOWER OHIO VALLEY/MID MISSISSIPPI VALLEY FRIDAY INTO SATURDAY. CONFIDENCE HAS IMPROVED IN KEEPING THE FORECAST DRY WEDNESDAY THROUGH THURSDAY NIGHT...AS NO RECENT MODELS HAVE ROTATED A SIGNIFICANT ENOUGH DISTURBANCE THROUGH THE BASE OF THE TROUGH TO DRAG PRECIPITATION INTO THE FOUR STATE REGION. CONFIDENCE IS ALSO INCREASING IN TIMING OF THE PRIMARY COLD FRONT THROUGH THE REGION FRIDAY AND FRIDAY NIGHT...AS THE 12Z GFS AND ECMWF BOTH HAVE THIS GENERAL TIMING. POPS ARE STILL RATHER LOW THESE PERIODS...AS THE MODELS NEED TO SHOW SOME STABILITY FIRST. ALSO...SURFACE RIDGING IS EXPECTED TO PERSIST BETWEEN HERE AND THE GULF COAST...SO THERE WILL BE LITTLE IN THE WAY OF RETURN FLOW OF MOISTURE INTO THE FRONT. THAT SAID...THE MID AND UPPER LEVEL FORCING MAY BE STRONG ENOUGH TO GENERATE SOME ELEVATED INSTABILITY...SO KEPT THUNDER MENTION AREAWIDE FRIDAY AND FRIDAY NIGHT. SLIGHT POPS ARE FORECAST FOR SATURDAY AND SATURDAY NIGHT TO ACCOUNT FOR THE 00Z ECMWF TIMING OF THE FRONT. THE 00Z ECMWF ENSEMBLES DID SHOW SOME SUPPORT FOR THE OLD OPERATIONAL RUN...SO CANNOT RULE IT OUT JUST YET. AS FOR TEMPERATURES...IT WILL FEEL RATHER COOLISH WITH HIGHS NEAR 70 AND PLENTY OF SUNSHINE WEDNESDAY. A NICE WARMING TREND IS EXPECTED THURSDAY AND FRIDAY WITH A FEW 80S POSSIBLE ON FRIDAY. LOOKS LIKE PLEASANT EARLY FALL CONDITIONS FOR NEXT WEEKEND...ESPECIALLY IF THE OLD ECMWF IS NOT RIGHT. TEMPERATURES WILL BE A COUPLE OF CATEGORIES BELOW NORMAL...BUT STILL IN THE 70S FOR HIGHS. && .AVIATION... ISSUED AT 1230 PM CDT SUN SEP 16 2012 AREAS OF RAIN/SHOWERS DIMINISHED THIS MORNING...AND THE ACCOMPANYING IFR CONDITIONS AT KPAH/KCGI WERE IMPROVING. SOME BREAKS IN THE CLOUDS THIS AFTERNOON WILL BURN OFF THE REMAINDER OF THE IFR LOW CLOUDS AND FOG. VFR CONDITIONS ARE EXPECTED THIS EVENING...FOLLOWED BY A NORTHWARD RETURN OF SHOWERS AND LOCAL IFR CONDITIONS OVERNIGHT. THE IFR CIGS AND VSBYS WILL BE MAINLY AT THE KCGI/KPAH SITES MONDAY MORNING...BUT DETERIORATING CONDITIONS ARE EXPECTED AT ALL SITES. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ SHORT TERM...MY LONG TERM....DRS AVIATION...MY
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
358 PM EDT SUN SEP 16 2012 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 356 PM EDT SUN SEP 16 2012 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A W FLOW ALF OVER THE GRT LKS BTWN DEEPENING TROF IN SCNTRL CAN AND PROGRESSIVE SHRTWV RDG MOVING THRU THE GRT LKS. THERE IS A WEAK SHRTWV EMBEDDED IN THIS FLOW MOVING THRU WRN LK SUP EARLY THIS AFTN...BUT DRY AIRMASS DOMINATING THE AREA AND SHOWN ON THE 12Z RAOBS IS LIMITING ANY ACCOMPANYING WX TO JUST SOME PATCHY MID/HI CLDS. A STEADY WSW LLVL FLOW BTWN SFC HI PRES MOVING INTO THE MID ATLANTIC STATES AND A LO PRES TROF OVER THE KEWEENAW/WRN LK SUP ASSOCIATED WITH THE SHRTWV IS BEGINNING TO DRAW MORE SFC-H9 MSTR SHOWN ON THE 12Z MPX RAOB TOWARD THE AREA...BUT SFC DEWPTS HAVE MIXED OUT TO AS LO AS THE MID 40S AS OF EARLY THIS AFTN OVER THE CWA IN ADVANCE OF THIS LLVL MOISTENING. FARTHER TO THE NW...A SHARP COLD FNT STRETCHES FM NW ONTARIO ACRS MN INTO SDAKOTA. DUE TO THE DRYNESS OF AIRMASS AHEAD OF THIS FNT... THERE IS CURRENTLY NO SHRA AHEAD OF THIS BNDRY. BUT MORE CLDS/SOME -SHRA ARE EVIDENT OVER NDAKOTA IN THE COLD AIR TRAILING THE FNT WITH APRCH OF SHRTWVS EMBEDDED IN THE DEEPENING TROF OVER SCNTRL CAN AND ACCOMPANYING DPVA/H7-3 QVECTOR CNVGC AS WELL AS UPR DVGC IN RRQ OF ASSOCIATED H3 JET MAX NEAR LK WINNIPEG. LATE THIS AFTN/EARLY EVNG...ISSUED WILDFIRE POTENTIAL STATEMENT EARLIER IN THE SHIFT TO ACCOUNT FOR COMBINATION OF WELL ABV NORMAL TEMPS...MIN RH FALLING TO 30-35 PCT...GUSTY WSW WINDS ENHANCED BY DEEP MIXING...AND RECENT DRYNESS. THE MOST CRITICAL CONDITIONS ARE OVER THE SCNTRL...WHERE SHARPER PRES GRADIENT/HIER WINDS ARE EVIDENT. QUESTION IS WHETHER RETURNING LLVL MSTR SHOWN ON THE 12Z MPX RAOB MIGHT CAUSE SOME CONVECTION ON INCOMING LO PRES TROF UNDER SOME DPVA/H85-5 QVECTOR CNVGC ASSOCIATED WITH APRCHG SHRTWV. RECENT GFS RUNS HAVE BEEN QUITE CONSISTENT SHOWING SOME CONVECTION. SINCE THE 12Z RAPID REFRESH RUC MODEL...THE FINER RES CNDN MODEL...AND THE NAM HINT SOME CONVECTION WL IMPACT MAINLY THE CNTRL ZNS WHERE LLVL MOISTENING AND DYNAMICS COME INTO PHASE NEAR PEAK HEATING TIME... MAINTAINED SCHC POPS OVER THE CNTRL DESPITE MID LVL DRYNESS THAT WL LIMIT COVERAGE OF ANY ASSOCIATED SHRA/TS TO ISOLD. TNGT...ANY INSTABILITY SHRA/TS WL DISSIPATE WITH LOSS OF DAYTIME HEATING/ARRIVAL OF SOME DNVA/H85-5 QVECTOR DVGC IN THE WAKE OF INITIAL SHRTWV PASSAGE. THEN COLD FNT ASSOCIATED WITH DEEPENING TROF IN CANADA IS PROGGED TO PUSH ACRS THE W HALF OF UPR MI BY 12Z MON. SINCE THE SHARPEST H7-3 QVECTOR CNVGC ASSOCIATED WITH SHRTWVS MOVING THRU THE AMPLIFYING UPR TROF/UPR DVGC IN RRQ OF H3 JET MAX MOVING INTO NW ONTARIO IS FCST TO FOLLOW THE FROPA...EXPECT THE BULK OF ANY PCPN TO FALL ON THE COLD SIDE OF THE BNDRY...AS IS OBSVD TODAY IN THE NRN PLAINS. GOING POPS INCRSG TOWARD CATEGORICAL OVER THE W APPEAR PRETTY MUCH ON TRACK...BUT DID CUT POPS OVER THE E HALF WITH AN ABSENCE OF UPR FORCING IN THAT AREA WITHIN DRIER AIRMASS AHEAD OF THE FROPA. MON...AREA OF SHRA/CATEGORICAL POPS OVER THE W HALF IN THE MRNG SHOULD SPREAD INTO THE E AS UPR TROF AXIS SHIFTS SLOWLY TO THE E AND AREA OF IMPRESSIVE H7-3 QVECTOR CNVGC/UPR DVGC IN RRQ OF UPR JET TO THE N SHIFTS TO THE E FOLLOWING SFC COLD FROPA. ALTHOUGH MODELS INDICATE SOME MID LVL DRYING MIGHT IMPACT THE W IN THE AFTN... ARRIVAL OF COLDER H85 AIR...WITH TEMPS AT THAT LVL FCST NEAR 0C OVER THE W LATER IN THE DAY...IN CYC NLY FLOW TO W OF SFC LO THAT DVLPS ON THE COLD FNT TO THE E SHOULD MAINTAIN LK ENHANCED SHOWERS IN THAT AREA THRU 00Z TUE. ALTHOUGH TEMPS MIGHT WARM A BIT OVER THE E BEFORE COLD FROPA/THICKER CLDS ARRIVE...READINGS ARE LIKELY TO FALL FOLLOWING THE FROPA. SO NON-DIURNAL TEMP CURVE WITH STEADY/SLOWLY FALLING TEMPS AT MOST PLACES IN THE AFTN APPEARS IN ORDER. DID RETAIN A MENTION OF TS OVER THE E NEAR AND JUST BEHIND FROPA TIME AS NAM FCST SDNGS HINT AT MUCAPE UP TO 500 J/KG. WITH A GUSTY N WIND... SHRA... AND FALLING TEMPS THRU THE 50S...MON WL HAVE A DISTINCT AUTUMNAL FEEL. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 356 PM EDT SUN SEP 16 2012 MAIN CONCERN IN THE MON NIGHT-WED TIME PERIOD CONTINUES TO BE POPS...AND ALSO THE POSSIBILITY OF A HARD FREEZE TUESDAY NIGHT ACROSS THE INTERIOR. NO MAJOR CHANGES OF FORECAST THINKING FOR MONDAY NIGHT. THE UPPER TROUGH GRADUALLY SETTLES ACROSS THE UPPER LAKES MONDAY NIGHT...CENTERED OVER LAKE SUPERIOR BY TUESDAY MORNING. DESPITE THE SURFACE LOW MOVING NE AND AWAY FROM THE REGION...A LAKE AGGREGATE TROUGH WILL PERSIST ACROSS THE LAKE AS THE UPPER TROUGH MOVES OVERHEAD. THIS WILL KEEP PBL WINDS PEGGED TO A NORTHERLY DIRECTION ACROSS THE LAKE WHICH COMBINED WITH STEEPENING LOW LEVEL LAPSE RATES AS THE 850MB TEMPS DROP TO -3C SHOULD FAVOR A FAIRLY PERSISTANT RAIN ACROSS NORTH CENTRAL UPPER MICHIGAN MONDAY NIGHT. THERE ARE SOME DIFFERENCES BETWEEN THE GFS AND NAM REGARDING THE EVOLUTION OF LOW LEVEL WIND FLOW. THE GFS SUGGESTS THE WIND WILL BACK SLIGHTLY MONDAY NIGHT OVER UPPER MI WHICH WOULD KEEP THE HEAVIEST PCPN JUST TO THE EAST OF MARQUETTE. MEANWHILE...THE NAM WANTS TO KEEP THE WINDS A LITTLE EAST OF NORTH...WHICH WOULD BE HIGHLY FAVORABLE FOR THE HIGHER ELEVATIONS WEST OF MARQUETTE. WOULD NOT BE SURPRISED IF THE GFS WIND VERIFIES...BUT IT MAY NOT MAKE A DIFFERENCE IN PCPN CHANCES GIVEN THE LAKE ENHANCED NATURE OF THE PCPN VS. LAKE EFFECT. THE NAM AND GFS ALSO SUGGEST THAT THE RAIN WILL DIMINISH MON NIGHT SOME OF THE MID LEVEL MOISTURE BRIEFLY SCOURS OUT BEFORE A REINFORCING SHOT OF MOISTURE MOVES IN BY TUE MORNING. ALTHOUGH THIS MAY HAPPEN...THE FACT THAT THE LAKE INDUCED EQULIBRIUM LEVEL RISES TO OVER 20 KFT OVERNIGHT MONDAY AND LARGE SCALE FORCING PERSISTS AS THE UPPER TROUGH MOVES OVERHEAD SHOULD HELP TO OFFSET ANY MID LEVEL DRYING. THE 4KM NAM NEST AND THE LOCAL WRF-ARW SUGGEST THE LAKE ENHANCED PCPN WILL DEVELOP IN EARNEST AS SOON AS THE 850MB TEMPS DROP...SOON AFTER 00Z. IN ADDITION...THE MORE LAKE ENHANCED NATURE OF THE PCPN /VS LAKE EFFECT/ WOULD SUGGEST A MORE EVENLY DISTRUBUTED AREA OF PCPN ACROSS ALL OF NORTH CENTRAL UPPER MI. WITH ALL OF THIS BEING SAID...WILL KEEP CATEGORICAL POPS FOR MUCH OF NORTH CENTRAL UPPER MICHIGAN CLOSER TO LAKE SUPERIOR...SIMILAR TO PREVIOUS FORECASTS. AS FOR THE FAR EAST...PCPN MAY LIGHTEN UP MON NIGHT AS NORTHERLY PBL FLOW NOT TERRRIBLY FAVORABLE FOR PCPN IN THAT AREA. WITH THE UPPER TROUGH OVERHEAD ON TUESDAY...AND NEUTRAL TO SLIGHTLY CYCLONIC PBL FLOW...WILL OPT TO MAINTAIN POPS AND RAISE THEM SLIGHTLY TUESDAY NEAR LAKE SUPERIOR. AS THE TROUGH EXITS DURING THE DAY...THE ASSOCIATED MID LVL FORCING WILL EXIT. THIS WILL ALLOW FOR THE SURFACE RIDGING TO BUILD IN DURING THE DAY AND AS SUCH SHOULD ALLOW FOR LAKE EFFECT PCPN TO GRADUALLY DIMINISH BY EVENING. AM NOT IN TOO MUCH OF A HURRY TO END PCPN ON TUESDAY THOUGH...AS THE RIDGE AXIS REALLY DOES NOT BUILD IN UNTIL AFTER 00Z WED. TEMPS WILL STRUGGLE TO REACH 50 ACROSS THE INTERIOR DUE TO CLOUDS AND SHOWERS. IN FACT...ALL NWP WANTS TO KEEP THE INTERIOR IN THE MID-UPPER 40S ON TUESDAY. THIS SEEMS REASONABLE ESPECIALLY IF CLOUDS PERSIST...AND HAVE THEREFORE LOWERED TEMPS ACROSS THE ENTIRE AREA ON TUESDAY...WITH MOST INTERIOR SECTIONS STAYING IN THE 40S. ANY REMAINING SHOWERS SHOULD END EARLY TUE EVENING...THEN THE RIDGE BUILDS IN. THIS RIDGING COMBINED WITH PRECIPITABLE WATER VALUES AS LOW AS 0.45 INCH SHOULD ALLOW FOR SKIES TO CLEAR OUT ACROSS THE WEST. LAKE CLOUDS SHOULD HANG ON EAST...BUT EVEN THERE IT MAY CLEAR OUT BY MORNING. REGARDLESS...WITH CLEAR SKIES AND LIGHT WINDS...IT SHOULD GET COLD ACROSS THE INTERIOR. AM NOW THINKING A HARD FREEZE IS IN STORE BY WED MORNING FOR THE INTERIOR WEST. EVEN THE RAW NAM WHICH USUALLY HAS A WARM BIAS DURING RADIATIONAL COOLING HAS TEMPS ACROSS IRON COUNTY IN THE 20S...AND THE GFS HAS 2M TEMPS IN THE LOWER 30S. NAM MOS GUIDANCE SUGGEST SIMILAR TO COLDER TEMPS FOR TUE NIGHT. WILL THEREFORE LOWER TEMPS ACROSS THE ENTIRE AREA TUE NIGHT. SOME MODEL DIFFERENCES REGARDING THE NEXT SYSTEM. THE GFS IS MUCH FASTER...UP TO 12 HRS...BRINIGING PCPN IN BY LUNCHTIME WED. MEANWHILE...THE NAM AND GEM ARE MUCH SLOWER...NOT BRINGING IN PCPN UNTIL WED EVENING. THE COMBINATION OF THE INCREASING WARM ADVECTION/ISENTROPIC LIFT AND INCREASING MID LVL MOISTURE ACROSS THE WEST WED AFTN IN THE NAM WOULD IMPLY AT LEAST A CHANCE FOR RAIN WED AFTN DESPITE THE MODEL NOT PRINTING OUT MUCH QPF. WILL THEREFORE GO WITH 30 PCPN CHANCE FOR SHOWERS WED AFTN FOR WESTERN UPPER MI. WILL KEEP A DRY FCST FOR THE REMAINDER OF THE AREA. IN THE EXTENDED /WED NIGHT-NEXT SUNDAY/...THE FULL AMPLITUDE LONG WAVE TROUGH WILL PERSIST FROM HUDSON BAY THROUGH THE GREAT LAKES REGION THROUGH THE PERIOD. THIS WILL KEEP THE WEATHER FAIRLY UNSETTLED THROUGH SATURDAY. THE NUMERICAL GUIDANCE IS IN GOOD AGREEMENT REGARDING THE LONG WAVE...BUT DIFFER SOMEWHAT ON SPECIFIC DETAILS REGARDING INDIVIDUAL SHORT WAVES AND AS SUCH THEY DIFFER ON EXACT POSITION OF THE LONG WAVE TROUGH. THE MAIN OUTLIER WITH THE 00Z RUN IS THE OPERATIONAL ECMWF WHICH KEEPS THE MAIN TROUGH POSITIVLY TILTED WITH THE TROUGH AXIS FURTHER WEST. THIS IS LIKELY DUE TO THAT MODEL ALLOWING STRONGER SHORT WAVE ENERGY TO DIVE DOWN THE BACK SIDE OF THE UPPER TROUGH THURSDAY INTO FRIDAY. AT THIS TIME...THIS IS NOT SUPPORTED BY THE GFS...NOR THE MAJORITY OF THE ENSEMBLE MEMBERS FROM THE GFS AND ECMWF. WILL THEREFORE TREND THE FORECAST TOWARD THE GFS/GEM COMPROMISE...BUT THE REALITY OF THE MATTER IS THAT EITHER SOLUTION WOULD MAINTAIN UNSETTLED WEATHER FOR THE AREA FOR MUCH OF THE EXTENDED. THERE WILL BE PERIODS OF DRY WEATHER...BUT GIVEN THE UNCERTAINTY OF EXACT SHORT WAVE POSITIONS ESPECIALLY FOR LATE INTO THE WEEK...IT WILL BE TOUGH TO PIN DOWN SPECIFICS. WITH THAT BEING SAID...WILL NEED TO GO WITH CHANCE POPS EACH DAY OF THE EXTENDED THROUGH SATURDAY. THE BEST CHANCE FOR RAIN MAY BE FRIDAY INTO FRIDAY NIGHT WHERE THE GFS AND GEM BOTH AGREE ON A WAVE MOVING ACROSS THE UPPER LAKES WITH LOW PRESSURE ACROSS THE AREA. IN FACT...EVEN THE ECMWF SHOWS PCPN FRIDAY. BY SUNDAY...THE GFS SUGGESTS THAT THE TROUGH WILL SLOWLY EXIT EAST OF THE AREA...ALLOWING SOME DRYING TO MOVE IN. WILL THEREFORE GO WITH A DRY FORECAST FOR NOW ON SUNDAY...BUT THAT IS SUBJECT TO CHANGE IF THE TROUGH IS A LITTLE SLOWER. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 120 PM EDT SUN SEP 16 2012 VFR CONDITIONS WILL PREVAIL THROUGH THE REST OF THIS AFTERNOON AND INTO THE LATE HOURS TONIGHT. WINDS WILL GRADUALLY SWITCH FROM A MORE SOUTHWEST-WESTERLY DIRECTION TO NORTHWEST AS THE FRONT PASSES LATER ON THIS EVENING. A LOW PRESSURE TROUGH CROSSING UPPER MICHIGAN WILL DEVELOP INTO A MORE ORGANIZED LOW PRESSURE SYSTEM...BRINGING A WAVE OF PRECIPITATION INTO UPPER MICHIGAN DURING THE TOMORROW MORNING-LATE AFTERNOON TIME PERIOD. EXPECT WITH MORE MODERATE RAIN DEVELOPING THAT CEILINGS AND VISIBILITY WILL DROP FROM VFR CONDITIONS INTO A MORE IFR REGIME. KIWD/KCMX WILL SEE RAIN STARTING AROUND THE 10-11Z TIME...WHEREAS KSAW WILL START TO SEE LIGHT RAIN AROUND 15Z. GUIDANCE SUGGESTS THAT CEILINGS/VIS COULD DROP TO LIFR-VLIFR IN THE EARLY MORNING/EARLY AFTERNOON...BUT CONFIDENCE WAS NOT HIGH ENOUGH TO INCLUDE IN THE TAF. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 356 PM EDT SUN SEP 16 2012 EXPECT RELATIVELY LIGHT WINDS UNDER 20 KTS FOR MOST OF THIS EVENING OVER THE LAKE WITH FAIRLY HI STABILITY/A WEAK LO PRES TROF CROSSING THE AREA. THEN EXPECT A WIND SHIFT TO THE NNW WITH THE PASSAGE OF A STRONG COLD FRONT BY LATE EVENING OVER THE W AND THEN ON MON MORNING OVER THE E HALF. AS COLDER AIR FOLLOWS THE FRONT OVER THE RELATIVELY WARM WATERS OF LAKE SUPERIOR AND STABILITY DECREASES...EXPECT STRONGER N WINDS TO 25 TO 30 KTS TO DEVELOP W TO E. BUT SINCE LATEST GUIDANCE INDICATES THE PRES GRADIENT WILL BE WEAKER THAN EXPECTED ON PREVIOUS SHIFTS...GALES NOW APPEAR UNLIKELY. SO THE GOING GALE WATCH THAT WAS IN EFFECT ON MON OVER PORTIONS OF THE W HALF WAS DROPPED. NORTH WINDS WILL PERSIST MONDAY NIGHT INTO TUESDAY BEFORE GRADUALLY SHIFTING TO THE NW THEN W BY TUESDAY EVENING. ANOTHER LOW PRESSURE TROUGH WILL APPROACH WED THEN PASS ACROSS THE LAKE WED NIGHT. AHEAD OF THE TROUGH...WINDS WILL TURN SOUTHERLY AT 15-25 KT...THEN WILL TURN W-NW BY THU MORNING. OTHER THAN SOME GUSTS CLOSE TO GALE FORCE MONDAY EVENING...GALES ARE NOT EXPECTED AT THIS TIME THROUGH FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...MRD AVIATION...MCD MARINE...KC/MRD
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
426 PM EDT SUN SEP 16 2012 .SYNOPSIS... HIGH PRESSURE WILL SHIFT OFFSHORE TONIGHT AND MONDAY. A STRONG COLD FRONT WILL APPROACH THE AREA TUESDAY AND MOVE OFFSHORE WEDNESDAY...FOLLOWED BY HIGH PRESSURE FOR LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... AS OF 315 PM SUNDAY...ISENTROPIC LIFT AND A WEAK MID-LEVEL SHORTWAVE HAS CONSPIRED TO BRING PATCHY LIGHT RAIN OVER MAINLY THE WEST AND NORTHWEST PORTIONS OF THE CWA TODAY. ANOTHER WEAK SHORTWAVE EMBEDDED IN THE ZONAL MID-LEVEL FLOW WILL CROSS THE REGION OVER THE NEXT FEW HOURS AND WILL KEEP CHANCE POPS TO THE WEST OF HIGHWAY 17 THROUGH THE EVENING HOURS. BOTH THE RAP AND NAM12 SHOW PRECIPITATION DISSIPATING AROUND DARK WITH MINIMAL CHANCES OVERNIGHT. SKIES SHOULD BE MOSTLY CLOUDY OVERNIGHT AND HAVE GONE A LITTLE ABOVE GUIDANCE TEMPS TONIGHT WITH MINS IN THE LOWER TO MIDDLE 70S WITH UPPER 60S OVER THE OUTER BANKS. && .SHORT TERM /MONDAY/... AS OF 315 PM SUNDAY...WITH THE LOW-LEVEL FLOW VEERING TO MORE SOUTHEASTERLY ON MONDAY...EXPECT CLOUDY SKIES ACROSS THE REGION. PER LATEST NAM12/GFS...THINK BULK OF THE PRECIPITATION CHANCES WILL BE OVER THE FAR WESTERN COUNTIES ONCE AGAIN WITH MOST ACTIVITY HOLDING OFF UNTIL LATER IN THE DAY. WITH THE CLOUD COVER...MAXIMUM TEMPERATURES WILL BE FAIRLY UNIFORM ACROSS THE REGION WITHIN A DEGREE OR TWO OF 80. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... AS OF 400 PM SUNDAY...A ROBUST NRN STREAM UPPER LEVEL TROUGH WILL BE DIGGING SEWD ACROSS THE MID WEST TO START THE LONG TERM. THE TROUGH WILL ABSORB A WEAK SRN STREAM TROUGH PRESENTLY OVER EASTERN TX AS WELL AS TAP INTO ABUNDANT GOM MOISTURE AS IT PROGRESSES INTO THE MID ATLANTIC TUE AND TUE NIGHT. WILL SEE H85 MOISTURE TRANSPORT AND BULK SHEAR GRADUALLY INCREASE MON NIGHT HOWEVER DEEPEST MOISTURE AND UPPER LEVEL SUPPORT EXPECTED TO REMAIN WEST OVER THE APPALACHIANS/WESTERN PIEDMONT THROUGH THE OVERNIGHT PERIOD AND HAVE BACKED POPS OFF TO SLIGHT CHANCE. UPPER LEVEL DYNAMICS IMPROVE TUE/TUE NIGHT AS THE RIGHT ENTRANCE OF THE UPPER JET MOVES OVER THE REGION ALONG WITH DEEPEST MOISTURE TRANSPORT ACROSS ERN NC BRINGING THE BEST CHANCE OF SHOWERS/STORMS ACROSS THE REGION. MODERATE SHEAR AND INSTABILITY WILL BE PRESENT AND COULD SEE STRONG TO SEVERE STORMS DEVELOP TUE AFTERNOON/EVENING...AND SPC HAS THE REGION IN A SLIGHT RISK FOR SEVERE ON DAY3. WHILE INSTABILITY WILL WANE TUE NIGHT...FRONTAL FORCING MAY BRING ADDITIONAL STRONG STORMS ACROSS THE REGION. THE FRONT PUSHES TO THE COAST WED MORNING THEN STALLS NEAR THE GULF STREAM INTO THU. MODELS DIFFER SOME ON AMOUNT OF MOISTURE THAT REMAINS INVOF THE FRONT BUT COULD SEE LIGHT SHOWERS LINGERING INTO THU...ESPECIALLY COASTAL SECTIONS AND HAVE KEPT SLT CHC POPS THROUGH THE PERIOD. SUBSTANTIAL MID LEVEL DRYING PROGGED TO OCCUR THU THROUGH SAT BRINGING MAINLY DRY CONDITIONS BUT COULD SEE ISOLATED SHOWERS DEVELOP THROUGH PEAK HEATING FRI AS MODELS INDICATING A WEAK SHORTWAVE MOVING THROUGH THE CYCLONIC FLOW ALOFT WITH THE UPPER TROUGH PERSISTING ACROSS THE ERN CONUS. ANOTHER ROBUST NRN STREAM SYSTEM PROGGED TO DIVE INTO THE GREAT LAKES REGION NEXT WEEKEND POTENTIALLY BRINGING A ROUND OF SHOWERS ACROSS THE REGION SUNDAY...HOWEVER THIS SYSTEM LOOKS DRIER AND WEAKER WITH A LIMITED GULF MOISTURE FEED. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... SHORT TERM /TONIGHT AND MONDAY/... AS OF 315 PM SUNDAY...ANOTHER TRICKY AVIATION FORECAST OVERNIGHT TONIGHT. BEST GUESS HERE IS THAT EXTENSIVE CLOUD COVER SHOULD LIMIT THE FORMATION OF DENSE FOG. NUMERICAL GUIDANCE DOES SHOW SOME PERIODS OF MVFR STRATUS AND HAVE INCLUDED IN THE TAF BETWEEN ROUGHLY 08Z AND 13Z. REMAINDER OF TAF CYCLE SHOULD BE IN THE VFR RANGE. LONG TERM /MONDAY EVENING THROUGH THURSDAY/... AS OF 420 PM SUN...MAINLY VFR THROUGH MON NIGHT AS DEEPER MOISTURE AND BETTER CVRG OF PRECIP STAYS TO THE W. NUMEROUS SHRA AND A FEW TSRA WILL DEVELOP TUE/TUE NIGHT WITH PDS OF REDUCED CIGS AND VSBYS LIKELY. PRECIP WILL GRADUALLY END FROM W TO E WED WITH CIGS IMPROVING THROUGH THE DAY...HOWEVER A DEVELOPING LOW LEVEL INVERSION BEHIND THE FRONT MAY MAINTAIN MVFR CIGS INTO WED NIGHT. VFR CONDITIONS EXPECTED TO DOMINATE THU. && .MARINE... SHORT TERM /TONIGHT AND MONDAY/... AS OF 320 PM MONDAY...WILL EXTEND THE SMALL CRAFT ADVISORY FOR THE CENTRAL WATERS UNTIL 01Z TONIGHT AS SEEING OCCASIONAL 5 TO 6 FOOT SEAS OVER AT THE BUOY 13 MILES EAST OF OREGON INLET. REMAINDER OF COASTAL WATERS ARE IN THE 3 TO 5 FOOT RANGE...BUT STILL WITH 12 TO 13 SECOND SWELL PERIODS. LATEST WAVEWATCH SHOWS COMBINED SEAS SHOULD DROP TO 5 FEET OR LESS LATER TONIGHT THROUGH MONDAY. WINDS SHOULD CONTINUE FROM THE NE AT 15 KNOTS OR LESS. LONG TERM /MONDAY EVENING THROUGH THURSDAY/... AS OF 420 PM SUN...LITTLE CHANGE IN FORECAST REASONING THROUGH THE LONG TERM. SRLY WINDS GRAD INCREASE MON NIGHT AND ESPCLY TUE AS COLD FRONT APPROACHES....SPEEDS OF 20 TO 25 KTS LIKELY MOST WTRS LATER TUE. GUSTY S/SW WINDS WILL CONT TUE NIGHT THEN AS FRONT CROSSES WILL SEE NRLY WINDS DEVELOP BY LATER WED...POSS GUSTING TO AROUND 20 KTS. N TO NE WINDS AROUND 15 KTS WED NIGHT WILL SLOWLY DIMINISH THU. SEAS WILL BE 2 TO 4 FEET MON THEN BUILD TO 5 TO 7 FEET TUE AS WINDS RAMP UP. THE SEAS WILL REMAIN ELEVATED TUE NIGHT THEN GRAD SUBSIDE WED IN WAKE OF FRONT WITH SEAS DROPPING BELOW 6 FT ALL WTRS BY LATE IN THE DAY. SEAS WILL SUBSIDE TO 2 TO 3 FEET MOST WTRS THU WITH POSS STILL SOME 4 FOOTERS OUTER CNTRL AND NRN WTRS. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...BEACH HAZARDS STATEMENT UNTIL 8 PM EDT THIS EVENING FOR NCZ095- 103-104. MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR AMZ152- 154. && $$ SYNOPSIS...CTC NEAR TERM...CTC SHORT TERM...CTC LONG TERM...SK AVIATION...CTC/RF/SK MARINE...CTC/RF/SK
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
324 PM EDT SUN SEP 16 2012 .SYNOPSIS... HIGH PRESSURE WILL SHIFT OFFSHORE TONIGHT AND MONDAY. A STRONG COLD FRONT WILL APPROACH THE AREA TUESDAY AND MOVE OFFSHORE WEDNESDAY...FOLLOWED BY HIGH PRESSURE FOR LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... AS OF 315 PM SUNDAY...ISENTROPIC LIFT AND A WEAK MID-LEVEL SHORTWAVE HAS CONSPIRED TO BRING PATCHY LIGHT RAIN OVER MAINLY THE WEST AND NORTHWEST PORTIONS OF THE CWA TODAY. ANOTHER WEAK SHORTWAVE EMBEDDED IN THE ZONAL MID-LEVEL FLOW WILL CROSS THE REGION OVER THE NEXT FEW HOURS AND WILL KEEP CHANCE POPS TO THE WEST OF HIGHWAY 17 THROUGH THE EVENING HOURS. BOTH THE RAP AND NAM12 SHOW PRECIPITATION DISSIPATING AROUND DARK WITH MINIMAL CHANCES OVERNIGHT. SKIES SHOULD BE MOSTLY CLOUDY OVERNIGHT AND HAVE GONE A LITTLE ABOVE GUIDANCE TEMPS TONIGHT WITH MINS IN THE LOWER TO MIDDLE 70S WITH UPPER 60S OVER THE OUTER BANKS. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... AS OF 315 PM SUNDAY...WITH THE LOW-LEVEL FLOW VEERING TO MORE SOUTHEASTERLY ON MONDAY...EXPECT CLOUDY SKIES ACROSS THE REGION. PER LATEST NAM12/GFS...THINK BULK OF THE PRECIPITATION CHANCES WILL BE OVER THE FAR WESTERN COUNTIES ONCE AGAIN WITH MOST ACTIVITY HOLDING OFF UNTIL LATER IN THE DAY. WITH THE CLOUD COVER...MAXIMUM TEMPERATURES WILL BE FAIRLY UNIFORM ACROSS THE REGION WITHIN A DEGREE OR TWO OF 80. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... AS OF 220 AM SUNDAY...MADE VERY LITTLE CHANGE TO PREV FCST. HIGH PRES WILL SLIDE OFFSHORE MON WITH UPR TRF AND ASSOC COLD FRONT WILL APPROACH FROM THE W TUE. THE FRONT IS EXPECTED TO CROSS THE REGION WED. STILL LOOKS LIKE BULK OF THE DEEPER MOISTURE WILL REMAIN TO THE W OF AREA THRU MON NIGHT WITH LITTLE TO NO POP CST AND CHC DEEP INLAND. AXIS OF DEEPEST MOISTURE WILL CROSS LATER TUE AND TUE NIGHT JUST AHEAD OF FRONT AND CONT LIKELY POPS THIS TIME. WL BE WARM AND MODERATELY UNSTABLE TUE INTO TUE NIGHT AND A FEW STRONG STORMS WILL BE POSS. DRIER AIR WILL SPREAD IN BEHIND THE FRONT WED WITH PRECIP GRAD ENDING FROM W TO E DURING THE DAY. MAINLY DRY WEATHER THU AND FRI AS FRONT DRIFTS OFFSHORE AND WEAK HIGH PRES BUILDS IN FROM THE W. ANOTHER FRONT WILL CROSS LATE SAT BUT LIMITED MOISTURE AND LOWERED POPS TO SLIGHT CHC FOR SAT. HIGHS 80 TO 85 MON AND TUE THEN UPR 70S TO LOWER 80S REST OF THE PERIOD. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... SHORT TERM /TONIGHT AND MONDAY/... AS OF 315 PM SUNDAY...ANOTHER TRICKY AVIATION FORECAST OVERNIGHT TONIGHT. BEST GUESS HERE IS THAT EXTENSIVE CLOUD COVER SHOULD LIMIT THE FORMATION OF DENSE FOG. NUMERICAL GUIDANCE DOES SHOW SOME PERIODS OF MVFR STRATUS AND HAVE INCLUDED IN THE TAF BETWEEN ROUGHLY 08Z AND 13Z. REMAINDER OF TAF CYCLE SHOULD BE IN THE VFR RANGE. LONG TERM /MONDAY EVENING THROUGH THURSDAY/... AS OF 220 AM SUN...MAINLY VFR THROUGH MON NIGHT AS DEEPER MOISTURE AND BETTER CVRG OF PRECIP STAYS TO THE W. NUMEROUS SHRA AND A FEW TSRA WILL DEVELOP TUE AND CONT INTO TUE NIGHT WITH PDS OF REDUCED CIGS AND VSBYS LIKELY. PRECIP WILL END FROM W TO E WED WITH VFR BECOMING DOMINANT AND THAT SHLD CONT INTO THU AS HIGH PRES BUILDS IN FROM THE W. && .MARINE... SHORT TERM /TONIGHT AND MONDAY/... AS OF 320 PM MONDAY...WILL EXTEND THE SMALL CRAFT ADVISORY FOR THE CENTRAL WATERS UNTIL 01Z TONIGHT AS SEEING OCCASIONAL 5 TO 6 FOOT SEAS OVER AT THE BUOY 13 MILES EAST OF OREGON INLET. REMAINDER OF COASTAL WATERS ARE IN THE 3 TO 5 FOOT RANGE...BUT STILL WITH 12 TO 13 SECOND SWELL PERIODS. LATEST WAVEWATCH SHOWS COMBINED SEAS SHOULD DROP TO 5 FEET OR LESS LATER TONIGHT THROUGH MONDAY. WINDS SHOULD CONTINUE FROM THE NE AT 15 KNOTS OR LESS. LONG TERM /MONDAY EVENING THROUGH THURSDAY/... AS OF 220 AM SUN...HIGH PRES WILL DRIFT OFFSHORE MON WITH LIGHT E WINDS BECOME SE 10 TO 15 KTS LATE. SRLY WINDS GRAD INCREASE LATER MON NIGHT AND ESPCLY TUE AS COLD FRONT APPROACHES....SPEEDS OF 20 TO 25 KTS LIKELY MOST WTRS LATER TUE. GUSTY S/SW WINDS WILL CONT TUE NIGHT THEN AS FRONT CROSSES WILL SEE NRLY WINDS DEVELOP BY LATER WED...POSS GUSTING TO AROUND 20 KTS. N TO NE WINDS AROUND 15 KTS WED NIGHT WILL SLOWLY DIMINISH THU. SEAS WILL BE 2 TO 4 FEET MON THEN BUILD TO 5 TO 7 FEET TUE AS WINDS RAMP UP. THE SEAS WILL REMAIN ELEVATED TUE NIGHT THEN GRAD SUBSIDE WED IN WAKE OF FRONT WITH SEAS DROPPING BELOW 6 FT ALL WTRS BY LATE IN THE DAY. SEAS WILL SUBSIDE TO 2 TO 3 FEET MOST WTRS THU WITH POSS STILL SOME 4 FOOTERS OUTER CNTRL AND NRN WTRS. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...BEACH HAZARDS STATEMENT UNTIL 8 PM EDT THIS EVENING FOR NCZ095- 103-104. MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR AMZ152- 154. && $$ SYNOPSIS...CTC NEAR TERM...CTC SHORT TERM...CTC LONG TERM...SK AVIATION...CTC/SK MARINE...CTC/SK
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
100 PM EDT SUN SEP 16 2012 .SYNOPSIS... A WEAK FRONT STALLED ACROSS THE CAROLINAS WILL WEAKEN TODAY AS IT LIFTS BACK TO THE NORTH. LOW PRESSURE...DEVELOPING ALONG THE GULF COAST MONDAY...WILL MOVE THROUGH THE WESTERN CAROLINAS TUESDAY...BRINGING PERIODS OF SHOWERS AND THUNDERSTORMS TO THE AREA...WITH LOCALLY HEAVY RAIN POSSIBLE. A COLD FRONT WILL CROSS THE AREA EARLY WEDNESDAY...WITH HIGH PRESSURE BUILDING IN BEHIND IT CREATING COOLER AND DRIER WEATHER FOR THE END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 100 PM SUNDAY...FIRST SHOWERS OF THE DAY HAVE DEVELOPED ACROSS INLAND HORRY COUNTY AND SHOULD SPREAD NORTH AND WEST AS THE AFTERNOON WEARS ON. LATEST FEW HRRR RUNS SHOW THE AREA FROM WHITEVILLE TO THE GREEN SWAMP MAY HAVE AN INCREASING COVERAGE OF SHOWERS AND POSSIBLE STORMS OVER THE NEXT 4-5 HOURS. PREVIOUS DISCUSSION FROM 1000 AM FOLLOWS... THIS IS NOT AN EASY FORECAST FOR THE EASTERN CAROLINAS TODAY. A DISSIPATING STATIONARY FRONT EXTENDS FROM ABOUT 20 MILES SOUTH OF BALD HEAD ISLAND...ONSHORE NEAR MYRTLE BEACH...AND THEN NORTHWEST ACROSS THE EASTERN CAROLINAS IN A VERY NEBULOUS FASHION. BROAD AND WEAK LOW-LEVEL CONVERGENCE ALONG THIS FEATURE IS PROBABLY NOT ENOUGH BY ITSELF TO PRODUCE ANY CONVECTION LATER TODAY. WHAT MAY HELP PRODUCE CONVECTION HOWEVER IS THE PASSAGE OF SEVERAL WEAK UPPER LEVEL DISTURBANCES ACROSS CENTRAL AND EASTERN NORTH CAROLINA THROUGHOUT THE DAY. THE FIRST OF THESE IS CURRENTLY CREATING A LARGE AREA OF MODERATE RAIN AND SHOWERS JUST NORTH AND EAST OF RALEIGH. A SECOND IS CURRENTLY PRODUCING SHOWER ACTIVITY JUST NORTH OF CHARLOTTE. WHILE THE LARGEST IMPACT FROM THESE DISTURBANCES SHOULD REMAIN NORTH OF OUR FORECAST AREA...THE ASSOCIATED ACCELERATION OF THE 300 MB WIND IN A WEST-TO-EAST ORIENTED JET STREAK WILL OPEN UP A REGION OF UPPER-LEVEL DIVERGENCE OVER SOUTHEASTERN NORTH CAROLINA LATER TODAY. THIS IN COMBINATION WITH LOW-LEVEL CONVERGENCE ALONG SEABREEZE BOUNDARIES AND BUOYANCY FROM 500-800 J/KG OF SURFACE-BASED CAPE SHOULD PRODUCE SCATTERED SHOWERS AND PERHAPS ISOLATED T-STORMS THIS AFTERNOON. THE BEST CHANCES WILL PROBABLY EXTEND FROM THE BENNETTSVILLE-LUMBERTON AREA SOUTHEAST TOWARD THE POINT OF CAPE FEAR WHERE CONVERGING SEABREEZE BOUNDARIES OFTEN PRODUCE A LOCAL MAXIMUM IN LOW-LEVEL CONVERGENCE. IN TERMS OF MODEL PERFORMANCE...THE 06Z NAM CERTAINLY IS OUTPERFORMING THE 06Z GFS WITH MOISTURE DISTRIBUTION AND THE POSITION OF THE FRONT. THE NAM`S FORECAST CONCENTRATION OF SHOWERS MAY BE OVERDONE THIS AFTERNOON ACROSS OUR AREA GIVEN THE GLANCING BLOW FROM THE TRAIN OF UPPER DISTURBANCES AND OVERALL WEAK INSTABILITY. VIRTUALLY NO CHANGES TO HIGH TEMPERATURE FORECASTS HAVE BEEN MADE...STILL EXPECTING MID 80S IN THE SC PEE DEE REGION WITH LOWER 80S MOST OTHER PLACES. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 3 AM SUNDAY...STILL A WET PERIOD EXPECTED AS SPLIT FLOW 5H PHASING OCCURS AND A STORM SYSTEM RIDES UP THE APPALACHIANS. MONDAY...SOUTHERN STREAM VORT SPINS OUT OF TEXAS AND A SURFACE LOW DEVELOPS ACROSS THE GULF COAST. AT THE SAME TIME...HIGH PRESSURE DRIFTS OFF THE MID-ATLANTIC COAST AS A WARM FRONT PUSHES UP THROUGH THE CAROLINAS. DECENT THETA-E ADVECTION OCCURS BEHIND THE FRONT AS SOUTHERLY FLOW DEVELOPS THROUGH MUCH OF THE COLUMN. THIS WILL PROVIDE INCREASING CHANCES FOR SHOWERS ON MONDAY...BUT OTHER THAN THE FRONT ITSELF...OVERALL FORCING REMAINS DISPLACED WEST OF THE CWA SO ONLY CHC POP IS WARRANTED THROUGH MUCH OF THE DAY. MONDAY NIGHT INTO TUESDAY...850MB TRANSPORT WINDS RISE TO NEARLY 50 KTS AS THETA-E RIDGE AXIS MOVES DIRECTLY OVERHEAD. VORT IMPULSES AND ASSOCIATED PVA STAY JUST WEST OF THE CWA...BUT WE DO ENTER THE DIFFLUENT REGION OF A 300MB JET...WHICH SHOULD AID LIFT DURING TUESDAY. ADDITIONALLY...STRONG COLD FRONT WILL RAPIDLY PUSH EAST TOWARDS THE COAST DURING THE DAY...PROVIDING AN ADDITIONAL FOCUS FOR SHOWERS/TSTMS. AS NOTED BY PREVIOUS FORECASTER...THIS WILL BE A RAPIDLY EVOLVING AND MOVING SYSTEM...AND HPC HAS CUT BACK ON OVERALL QPF NUMBERS FOR THE EVENT...BUT AN AREAL AVERAGE OF AROUND ONE INCH SEEMS PLAUSIBLE AS ROUNDS OF SHOWERS/TSTMS WILL BE ACCOMPANIED BY PERIODS OF HEAVY RAINFALL. EVEN WITH VERY STRONG LOW LEVEL WIND FIELDS...AM NOT ANTICIPATING SEVERE WIND DUE TO LIMITED INSOLATION/INSTABILITY KEEPING LAPSE RATES QUITE WEAK. COLD FRONT CROSSES THE AREA AT THE VERY END OF THE PERIOD FROM WEST TO EAST...CAUSING RAPID DRYING THROUGH THE COLUMN...AND BY WEDNESDAY MORNING ALL BUT THE IMMEDIATE COAST SHOULD BE DONE WITH THE SHOWERS. MAX TEMPS THROUGH THE PERIOD WILL BE AROUND CLIMO...WARMER ON MONDAY SINCE TUESDAY WILL FEATURE WIDESPREAD CLOUD COVER AND SHOWERS. MINS MONDAY NIGHT WILL REMAIN WELL ABOVE CLIMO...FALLING ONLY TO AROUND 70 MOST SPOTS. TUESDAY NIGHT WILL FEATURE A DECENT TEMP GRADIENT FROM WEST TO EAST AS COLD FRONT CROSSES THE AREA...LOW 60S WELL NW TO AROUND 70 NEAR THE COAST. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 3 AM SUNDAY...COLD FRONT WILL BE CROSSING THE AREA AT THE VERY START OF THE PERIOD...AND BE OFFSHORE NO LATER THAN WEDNESDAY AFTN. DRY AND COLD ADVECTION OCCUR BEHIND THIS FRONT...AND WEDNESDAY WILL BE COOL DUE TO NE FLOW DEVELOPING AHEAD OF HIGH PRESSURE RIDGING DOWN THE COAST...BUT WITH CLEARING SKY CONDITIONS. THU-SAT LOOK TO BE DRY AS WELL EVEN AS UPPER TROUGHING PERSISTS ACROSS THE EAST THANKS TO A RELOADING VORT ACROSS THE GREAT LAKES REGION. SURFACE HIGH PRESSURE WILL RIDGE DOWN THE COAST AND REMAIN INTO THE WKND...WHILE FORECAST PROFILES SUGGEST A VERY DRY COLUMN ABOVE 900MB. THIS WILL KEEP SHOWERS TO A MINIMUM...AND WILL CARRY ONLY SILENT POP EACH DAY. A COLD FRONT WILL APPROACH AT THE VERY END OF THE PERIOD...BUT APPEARS TO BE MOISTURE STARVED AND MAY JUST SERVE AS A REINFORCING SHOT OF COOL/DRY AIR SATURDAY NIGHT. EXPECT TEMPS WEDNESDAY TO BE QUITE COOL...A FEW DEGREES BELOW CLIMO. OTHERWISE...SEASONABLE TEMPS THROUGH THE EXTENDED. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 18Z...WEAK FRONTAL BOUNDARY DRAPED FROM NEAR MYRTLE BEACH NW THROUGH LUMBERTON. THE FRONT WILL REFORM ACROSS SOUTH-CENTRAL NORTH CAROLINA IN THE OVERNIGHT HOURS. MODELS ARE NOT IN GOOD AGREEMENT WITH RESPECT TO DISTRIBUTION OF SHOWER ACTIVITY OVER THE NEXT 12 HRS...WITH THE NAM MUCH MORE WIDESPREAD WITH PRECIPITATION. THINK THERE WILL BE ENOUGH LIFT TO SUSTAINED CONVECTION ALONG AND NORTH OF THE FRONT THIS AFTERNOON. A MID CLOUD CEILING WILL LOWER TO NEAR MVFR BY EARLY EVENING...WITH PRECIPITATION INDUCED CEILINGS LOWERING TO AT LEAST 2K FEET THIS EVENING WITH MORE OF A STRATIFORM PRECIP REGIME. LBT STANDS THE BEST CHANCE FOR IFR CONDITIONS...PERHAPS SOMETIME AFTER MIDNIGHT. SURFACE WINDS WILL HAVE REMAIN EASTERLY THROUGH THE FORECAST PERIOD...MORE SOUTHERLY AT THE MYRTLE BEACH AIRPORTS MONDAY AS THE FRONT WAVES NORTH. THE EXTENDED OUTLOOK...MOISTURE WILL CONTINUE TO BE ON THE INCREASE WITH SCATTERED CONVECTION CONTINUING MONDAY NIGHT... BECOMING NUMEROUS ON TUESDAY WITH MODERATE CONFIDENCE FOR INTERMITTENT IFR CONDITIONS. CONVECTION WILL CONTINUE INTO WEDNESDAY WITH IMPROVING CONDITIONS THURSDAY INTO FRIDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 100 PM SUNDAY...NO SIGNIFICANT CHANGES WITH THE EARLY AFTERNOON UPDATE. PREVIOUS DISCUSSION FROM 1000 AM FOLLOWS... A DISSIPATING FRONT EXTENDS ACROSS FRYING PAN SHOALS AND ONSHORE NEAR MYRTLE BEACH. NORTH OF THIS BOUNDARY THERE HAS BEEN A STRONGER THAN EXPECTED PUSH ON ONSHORE WINDS WITH GUSTS ALONG THE NEW HANOVER COUNTY BEACHES REGISTERING 15 KNOTS THIS MORNING. AS THIS BOUNDARY WEAKENS FURTHER TODAY AND AS THE SEABREEZE CIRCULATION DEVELOPS WE EXPECT WINDS ALL ALONG THE COASTLINE DOWN THROUGH GEORGETOWN TO TURN EAST-SOUTHEASTERLY AT 10-15 KNOTS. CONSIDERABLE SWELL ENERGY FROM DISTANT HURRICANE NADINE HAS ARRIVED. THE FRYING PAN SHOALS BUOY IS REPORTING 5 FOOT SEAS EVERY 14 SECONDS...WITH 3-4 FT SEAS EVERY 15 SECONDS BEING REPORTED FROM THE NEARSHORE WRIGHTSVILLE BEACH CORMP BUOY. THESE VERY LONG PERIOD SWELLS OFTEN LOSE A GOOD DEAL OF AMPLITUDE AS THEY APPROACH THE SHALLOW WATERS WITHIN A FEW MILES OF THE BEACHES...BUT AREA SURF CAMS ARE STILL SHOWING SOLID 4 FOOT BREAKERS NORTH OF CAPE FEAR. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 3 AM SUNDAY...SEAS 2-4 FT MONDAY WILL BE MOSTLY SWELL DOMINATED THANKS TO A GROWING AMPLITUDE 11-13 SEC SE SWELL FROM DISTANT HURRICANE NADINE AND A WEAK GRADIENT PRODUCING ONLY LIGHT E/SE WINDS. AS A COLD FRONT APPROACHES FROM THE WEST...WINDS WILL VEER TO THE SOUTH AND INCREASE QUICKLY MONDAY NIGHT TO 10-15 KTS. THIS WILL HELP DRIVE WAVE HEIGHTS TO 3-5 FT EVEN AS NADINE`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