Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 07/19/08

AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
200 PM PDT FRI JUL 18 2008 .SYNOPSIS... HIGH PRESSURE TEMPORARILY BUILDING OVER THE AREA WILL LOWER THE MARINE LAYER TONIGHT. HOWEVER FOG IS LIKELY TO BE MORE WIDESPREAD AND AFFECT THE COASTAL MESAS AND LOWER WESTERN VALLEYS TONIGHT THROUGH MID SATURDAY MORNING. OTHERWISE PLEASANT WEATHER IS EXPECTED FOR SATURDAY. HOWEVER A STRONG SURGE OF MONSOON MOISTURE SATURDAY NIGHT INTO SUNDAY WILL BRING A RETURN OF THUNDERSTORMS OVER THE MOUNTAINS AND DESERTS THAT WILL CONTINUE INTO MONDAY. SOME OF THE SHOWERS AND THUNDERSTORMS MOVE WEST ACROSS THE VALLEYS AND REACH THE COAST SUNDAY EVENING. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM...TONIGHT THROUGH MONDAY... THREE WEATHER CONCERNS FOR SOUTHWEST CALIFORNIA DURING THIS PERIOD ARE THE DEPTH OF THE MARINE LAYER AND STRATUS BURN OFF/RETURN TIMES...THE RENEWED SURGE OF MONSOON MOISTURE...AND THE BUILDING SOUTH SWELL. MARINE LAYER INCREASED SLIGHTLY THIS MORNING TO AROUND 2200 FEET. THE HIGH PRESSURE RIDGE...WHOSE AXIS IS SHIFTING SOUTHWARD ACROSS THE AREA THROUGH TONIGHT SHOULD CAUSE THE SUBSIDENCE INVERSION TO LOWER AND STRENGTHEN A LITTLE MORE BEFORE WEAKENING ON SATURDAY. BASED ON NAM12 MODEL CROSS SECTION TRENDS AFTER BASELINING TO THIS MORNINGS OBSERVATIONS...MARINE LAYER DEPTH EXPECTED TO LOWER TO 1500 FEET THIS EVENING AND TO AROUND 1000 FEET BY SATURDAY MORNING. CROSS SECTIONS SHOW LAYER MEAN RH 96-100 PERCENT SO THICK STRATUS CLOUD LAYER LIKELY WITH MORE OF THE LOWER VALLEYS/COASTAL MESAS IMPACTED BY DENSE FOG LATE EVENING/OVERNIGHT. FOR SATURDAY NIGHT/SUNDAY MOIST UNSTABLE AIR MASS ALOFT EXPECTED TO INHIBIT STRATUS FORMATION...SEE BELOW. THE NEXT WEATHER PROBLEM TO ADDRESS IS THE RETURN OF MONSOON MOISTURE THIS WEEKEND. THE REMNANTS OF A LARGE MESOSCALE CONVECTIVE COMPLEX ARE SITTING OVER THE SOUTHERN GULF OF CALIFORNIA POISED TO BE DRAWN NORTHWESTWARD. WITH THE UPPER TROUGH APPROACHING THE NORTHERN/CENTRAL CALIFORNIA COAST TODAY AND PUSHING SLOWLY INLAND SATURDAY AND SUNDAY...A CLEFT IN THE RIDGE IS MADE FOR THIS MOISTURE TO BE PULLED UP. MODELS ALL SHOW SOUTHEAST DEVELOPING ALOFT ON SATURDAY WITH STRONG SOUTHEAST FLOW...25-40 KTS...IN THE LOW LEVELS UP THE GULF OF CALIFORNIA. STRONG SURGE OF MONSOON MOISTURE MOVING ACROSS SALTON SEA/COACHELLA VALLEY/MORONGO VALLEY/YUCCA VALLEY AND INTO JOHNSON/LUCERNE VALLEYS EXPECTED SATURDAY EVENING. ONLY THING THAT MIGHT INHIBIT CONVECTION ON SUNDAY WOULD BE EXTENSIVE DEBRIS CLOUDS FROM SATURDAY NIGHTS CONVECTION. HAVE TWEAKED THE WEATHER/POP/AND SKY COVER GRIDS TO ADD CHANCE OF THUNDERSHOWERS FOR SATURDAY EVENING OVER LOWER DESERT AREAS AND SPRINKLES FOR EARLY SUNDAY MORNING OVER MOUNTAINS/DESERTS FOR DISSIPATING OVERNIGHT CONVECTION...AS WELL AS UPPED POPS/QPF AMOUNTS SUNDAY EVENING OVER AREAS WEST OF THE MOUNTAINS. THIRD PROBLEM...WAMIII MODEL IS KNOWN FOR FLATTENING AMPLITUDE AND MISSING TIMING OF ARRIVING SOUTHERN HEMISPHERE SWELLS. IT USUALLY GETS THE DIRECTION AND THE PERIOD CORRECT THOUGH. THE RELATIVELY STEEP APPROACH ANGLE...190 DEGREES...MEANS ORANGE COUNTY AND ONLY A FEW PARTS OF SAN DIEGO COUNTY WILL BE AFFECTED. THE LONG PERIOD INDICATES A SIGNIFICANT AMOUNT OF SHOALING WILL OCCUR WITH SURF HEIGHTS EASILY DOUBLE THE SWELL HEIGHT ON BEACHES WITH STEEP SLOPE AND DIRECTLY FACING THE ARRIVING SWELL. RELAYING STRICTLY ON MODEL GUIDANCE WILL LIKELY RESULT IN UNDERFORECASTING OF SURF HEIGHTS AT THESE BEACHES BUT PROBABLY OVERFORECASTING AT THE WEST FACING BEACHES SINCE MOST OF THE SWELL ENERGY WILL PASS BY TO THE NORTH AND ONLY A THIRD TO A QUARTER OF IT WILL BE REFRACTED TOWARDS THESE BEACHES. && .LONG TERM TUESDAY THROUGH FRIDAY... BACKED OFF ON THREAT OF THUNDERSTORMS TUESDAY AND WEDNESDAY OVER THE MOUNTAINS/DESERTS BUT LEFT IN FOR THURSDAY AND BEYOND. GFS MODEL FOR AT LEAST LAST FOUR RUNS HAS BEEN SHOWING DRYING SOUTHWEST FLOW RETURNING TUESDAY AND WEDNESDAY IN THE 850-700 MB LAYER. AFTER WHICH SOUTHEAST FLOW RETURNS AS ANOTHER TROPICAL WAVE PASSES BY TO THE SOUTH. A VERY SHALLOW AND DISRUPTED MARINE LAYER WILL BRING NIGHT AND MORNING CLOUDS AND FOG TO COASTAL STRIP AND LOWER WESTERN VALLEYS BUT EXPECT ONSET TO BE LATER AND CLEARING TIMES EARLIER. && .AVIATION... 181915Z...MDCRS SOUNDINGS CONTINUE TO SHOW THE MARINE LAYER DEPTH TO BE AROUND 2000 FEET. EXPECT LITTLE CHANGE IN THE MARINE LAYER DEPTH THROUGH THE WEEKEND. A WEAK COASTAL EDDY SHOULD HELP MAINTAIN THE MARINE LAYER THROUGH THE WEEKEND. STRATUS WITH BASES AROUND 1400 FEET MSL ALONG THE IMMEDIATE COAST SHOULD SPREAD BACK INLAND OVER THE COASTAL VALLEY AND MESAS BETWEEN SUNSET AND 04Z AND THE WESTERN INLAND VALLEY AREAS BEFORE MIDNIGHT. STRATUS SHOULD REACH VICINITY OF KONT BETWEEN MIDNIGHT AND SUNRISE ON SATURDAY. BREAKUP ON SATURDAY SHOULD BE BETWEEN 16Z AND 18Z. ABOVE THE MARINE LAYER...EXCEPT FOR SOME AFTERNOON CU/TCU OVER THE MOUNTAINS DURING THE AFTERNOONS...A MOSTLY CLEAR SKY WITH UNRESTRICTED VISIBILITIES WILL CONTINUE THROUGH SATURDAY. MID AND HIGH LEVEL MOISTURE MOVING IN FROM THE SOUTHEAST SATURDAY NIGHT AND SUNDAY COULD BRING TSTMS TO THE MOUNTAINS AND DESERTS ON SUNDAY. MAX TEMPS FOR KPSP AND KTRM FOR SAT...42 TO 44C. HORTON && .MARINE... A MODERATE SOUTH SWELL WILL BEGIN TO MOVE INTO THE COASTAL AREAS TODAY...INCREASING THROUGH SUNDAY. THE PERIOD WILL INCREASE TO 19 SECONDS ON SATURDAY WITH THE PEAK OF THE SWELL EXPECTED ON SUNDAY WITH A PERIOD DROPPING TO 16 SECONDS BY SUNDAY AFTERNOON. SURF IS FORECAST TO BE UP TO 3 TO 6 FEET ON SATURDAY WITH SETS TO 9 FEET OR HIGHER MAINLY IN ORANGE COUNTY SUNDAY. A HIGH SURF ADVISORY WILL BE ISSUED FOR THE ORANGE COUNTY BEACHES FOR SATURDAY NIGHT THROUGH MONDAY NIGHT. THERE WILL BE STRONG AND DANGEROUS RIP CURRENTS DURING THE WEEKEND. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...HIGH SURF ADVISORY FROM 9 PM SATURDAY TO 2 AM PDT TUESDAY FOR ORANGE COUNTY COASTAL AREAS. QUANTITATIVE PRECIPITATION FORECAST...QPSSGX ISSUED 122 PM PDT FOR RAINFALL ESTIMATES THROUGH SUNDAY EVENING SPECIAL WEATHER STATEMENT...SPSSGX...ISSUED AT 116 PM PDT FOR RAINFALL AND FLASH FLOOD POTENTIAL. ALSO REFER TO LATEST HAZARDOUS WEATHER OUTLOOK. PZ...NONE. && $$ PUBLIC...BALFOUR AVIATION/MARINE...HORTON NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
AREA FORECAST DISCUSSION...CORRECTION
NWS SAN DIEGO CA
935 AM PDT FRI JUL 18 2008 CORRECTED SYNOPSIS, LONG TERM, AND FIRE WEATHER SECTIONS... .SYNOPSIS... THE MARINE LAYER DEPTH WAS NEAR 2200 FEET AND A STRONG INVERSION WILL KEEP THE CLOUDS FROM CLEARING ALONG THE COAST UNTIL LATE MORNING TODAY. A MOSTLY SUNNY AND THUNDERSTORM FREE DAY IS EXPECTED ELSEWHERE ACROSS SOUTHWEST CALIFORNIA. A STRONG SURGE OF MONSOON MOISTURE IS LIKELY THIS WEEKEND WITH A RETURN OF THUNDERSTORMS OVER THE MOUNTAINS AND DESERTS BY SUNDAY AND CONTINUING THROUGH MONDAY. SOME OF THESE MAY MOVE WEST ACROSS THE VALLEYS ON SUNDAY. THE MARINE LAYER DEPTH WILL SHRINK TO 1200 FEET AND LOW CLOUDS AND FOG SHOULD BE CONFINED TO THE COASTS AND LOWER WESTERN VALLEYS DURING THE LATE NIGHT AND EARLY MORNING HOURS. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (TODAY THROUGH SUNDAY)... THREE WEATHER CONCERNS DURING THIS PERIOD...THE DEPTH OF THE MARINE LAYER AND STRATUS BURN OFF/RETURN TIMES...THE RENEWED SURGE OF MONSOON MOISTURE...AND THE BUILDING SOUTH SWELL. MARINE LAYER HAS INCREASED SLIGHTLY FROM YESTERDAY...WHEN IT WAS CLOSE TO 2000 FEET DEEP...TO AROUND 2200 FEET DEEP THIS MORNING PER MORNING SOUNDING FROM KNKX AND THE MESONET OBSERVATIONS FROM FOOTHILLS AND UPPER VALLEYS. PIREP W OF ONTARIO 2200 FEET AGREES WITH SOUNDING. VISIBLE SATELLITE IMAGERY OVER SAN DIEGO COUNTY INDICATES STRATUS COVERING TERRAIN BELOW 1900 FEET ELEVATION. METARS SHOWING FAIRLY UNIFORM CLOUD BASES AROUND 1000 FT SO NORTH ISLAND RULE OF THUMB WOULD SAY CLEARING AT THE COAST BETWEEN 1030 AND NOON PDT BASED ON 1 HOUR AFTER SUNRISE FOR EVERY 200 FEET OF CLOUD THICKNESS. THIS LATER CLEARING WOULD ALSO BE SUPPORTED BY THE STRONGER SUBSIDENCE INVERSION THIS MORNING. ABOVE THE MARINE LAYER THERE HAS BEEN SIGNIFICANT DRYING IN THE 2500-10000 FOOT LAYER. THERE ARE ALSO SOME UPPER LEVEL CONVECTIVE DEBRIS CLOUDS PRESENT ABOVE THIS LAYER MOVING SOUTHWEST ACROSS RIVERSIDE COUNTY AND THEN SOUTHEASTWARD ACROSS SAN DIEGO COUNTY DUE TO THE CIRCULATION AROUND THE UPPER TROUGH/LOW THAT MOVED NORTHEAST AND EAST ACROSS THE REGION YESTERDAY/LAST NIGHT. THE HIGH PRESSURE RIDGE..WHOSE AXIS IS STILL TO THE NORTHWEST OF THE AREA WILL SHIFT SOUTHWARD ACROSS THE AREA TODAY/TONIGHT WHICH SHOULD CAUSE THE THE SUBSIDENCE INVERSION TO LOWER TODAY/TONIGHT AND STRENGTHEN A LITTLE MORE BEFORE WEAKENING ON SATURDAY. BASED ON NAM12 MODEL CROSS SECTION TRENDS AFTER BASELINING TO THIS MORNINGS OBSERVATIONS...MARINE LAYER DEPTH SHOULD LOWER TO 1500 FEET THIS AFTERNOON/EVENING AND TO AROUND 1000 FEET BY SATURDAY MORNING. CROSS SECTIONS SHOW LAYER MEAN RH 96-100 PERCENT SO THICK STRATUS CLOUD LAYER LIKELY WITH MORE OF THE LOWER VALLEYS/COASTAL MESAS IMPACTED BY DENSE FOG LATE EVENING/OVERNIGHT. FOR SATURDAY NIGHT/SUNDAY MOIST UNSTABLE AIR MASS ALOFT EXPECTED TO INHIBIT STRATUS FORMATION...SEE BELOW. THE NEXT WEATHER PROBLEM TO ADDRESS IS THE RETURN OF MONSOON MOISTURE THIS WEEKEND. A MONSTER MESOSCALE CONVECTIVE COMPLEX MOVED SOUTHWEST ACROSS THE MEXICAN STATES OF SOUTHERN SONORA AND SINALOA LAST NIGHT AND THE REMNANTS ARE SITTING OVER THE SOUTHERN GULF OF CALIFORNIA THIS MORNING. WITH THE UPPER TROUGH APPROACHING THE NORTHERN/CENTRAL CALIFORNIA COAST TODAY AND PUSHING SLOWLY INLAND SATURDAY AND SUNDAY...A CLEFT IN THE RIDGE IS MADE WITH SOUTHEAST DEVELOPING ALOFT ON SATURDAY AND STRONG SOUTHEAST FLOW...25-40 KTS...IN THE LOW LEVELS UP THE GULF OF CALIFORNIA. STAGE APPEARS SET FOR A STRONG SURGE OF MONSOON MOISTURE PUSHING UP SALTON SEA/COACHELLA VALLEY/MORONGO VALLEY/YUCCA VALLEY AND INTO JOHNSON/LUCERNE VALLEYS SATURDAY EVENING. ONLY THING THAT MIGHT INHIBIT CONVECTION ON SUNDAY WOULD BE EXTENSIVE DEBRIS CLOUDS FROM SATURDAY NIGHTS CONVECTION. WILL PROBABLY TWEAK CURRENT WEATHER GRIDS TO ADD CHANCE OF THUNDERSHOWERS FOR SATURDAY EVENING OVER LOWER DESERT AREAS AND SPRINKLES FOR EARLY SUNDAY MORNING OVER MOUNTAINS/DESERTS FOR DISSIPATING OVERNIGHT CONVECTION...AS WELL AS UP POPS OVER INLAND EMPIRE/SAN DIEGO COUNTY VALLEYS FOR SUNDAY EVENING/MONDAY. THIRD PROBLEM...WAMIII MODEL IS KNOWN FOR FLATTENING AMPLITUDE AND MISSING TIMING OF ARRIVING SOUTHERN HEMISPHERE SWELLS. IT USUALLY GETS THE DIRECTION AND THE PERIOD CORRECT THOUGH. THE RELATIVELY STEEP APPROACH ANGLE...190 DEGREES...MEANS ORANGE COUNTY AND ONLY A FEW PARTS OF SAN DIEGO COUNTY WILL BE AFFECTED. THE LONG PERIOD INDICATES A SIGNIFICANT AMOUNT OF SHOALING WILL OCCUR WITH SURF HEIGHTS EASILY DOUBLE THE SWELL HEIGHT ON BEACHES WITH STEEP SLOPE AND DIRECTLY FACING THE ARRIVING SWELL. RELAYING STRICTLY ON MODEL GUIDANCE WILL LIKELY RESULT IN UNDERFORECASTING OF SURF HEIGHTS AT THESE BEACHES BUT PROBABLY OVERFORECASTING AT THE WEST FACING BEACHES SINCE MOST OF THE SWELL ENERGY WILL PASS BY TO THE NORTH AND ONLY A THIRD TO A QUARTER OF IT WILL BE REFRACTED TOWARDS THESE BEACHES. && .LONG TERM MONDAY THROUGH THURSDAY...CORRECTED... AFTER MONDAY MIGHT BE OVERFORECASTING CONTINUOUS THREAT OF THUNDERSTORMS OVER THE MOUNTAINS/DESERTS INTO THURSDAY. IT APPEARS THE PATTERN IS NOT TOTALLY ANALOGOUS TO RECENT PROLONGED BOUT OF THUNDERSTORMS OVER MOUNTAINS/DESERTS. GFS MODEL FOR AT LEAST LAST THREE RUNS IS SHOWING DRYING SOUTHWEST FLOW RETURNING TUESDAY AND WEDNESDAY IN THE 850-700 MB LAYER. AFTER WHICH SOUTHEAST FLOW RETURNS AS ANOTHER TROPICAL WAVE PASSES BY TO THE SOUTH. IF TIME PERMITS AND 12Z GFS MODEL CONTINUES SUPPORT FOR THIS DRYING PERIOD...WILL MODIFY TUESDAY/WEDNESDAY WEATHER/POPS/SKY COVER GRIDS ACCORDINGLY. FROM PREVIOUS DISCUSSION...A SHALLOW MARINE LAYER WILL BRING AREAS OF NIGHT AND MORNING COASTAL LOW CLOUDS AND FOG EXTENDING LOCALLY INLAND. COVERAGE EARLY IN THE WEEK MAY BE FAIRLY PATCHY AT TIMES DUE TO THE DISRUPTIVE EFFECTS OF THE MONSOONAL MOISTURE. && .FIRE WEATHER... HAD ISSUED AN EARLIER CORRECTION TO THE DISCUSSION IN THE FIRE WEATHER FORECAST. THE STRONG DRYING TREND IN THE 2500-10000 FOOT LAYER MENTIONED IN THE FIRST PARAGRAPH ABOVE AS WELL AS THE LOWERING OF THE SUBSIDENCE INVERSION TO 1000 FEET TONIGHT...MEANS MUCH LOWER HUMIDITY TODAY AND SATURDAY WITH VERY POOR RECOVERY TONIGHT OVER THE MOUNTAINS. THE CURRENT RH GRIDS DO HAVE A DRYING TREND BUT MIGHT NOT BE NOT STRONG ENOUGH. WILL ADJUST THE DEWPOINT AND RH GRIDS LATER THIS MORNING AND ISSUE THE AFTERNOON NARRATIVE FIRE WEATHER FORECAST A LITTLE EARLIER THAN USUAL...BY 1300 PDT...TO GET THESE CHANGES OUT TO THE DISPATCH CENTERS. THIS DRYING TREND IS RELATIVELY SHORT LIVED...BASICALLY TODAY THROUGH SATURDAY...AFTER WHICH A SIGNIFICANT MOISTENING TREND OCCURS DUE TO THE STRONG SURGE OF MONSOON MOISTURE MENTIONED IN PARAGRAPH TWO ABOVE. MOST IF NOT ALL OF THESE THUNDERSTORMS EXPECTED TO BE ACCOMPANIED BY WETTING RAINS. && .AVIATION... 181430Z...MDCRS SOUNDINGS THIS MORNING PLACE THE MARINE LAYER DEPTH AROUND 1800 FEET...SLIGHTLY LOWER THAN ON THURSDAY. EXPECT LITTLE CHANGE IN THE MARINE LAYER DEPTH THROUGH THE WEEKEND. A WEAK COASTAL EDDY SHOULD HELP MAINTAIN THE MARINE LAYER THROUGH THE WEEKEND. STRATUS WITH BASES AROUND 1000 FEET MSL SHOULD PULL BACK TO THE COAST BETWEEN 15Z AND 17Z. LIMITED BREAKUP OF THE STRATUS ALONG THE IMMEDIATE COAST IS EXPECTED TODAY. STRATUS SHOULD SPREAD BACK INLAND OVER THE COASTAL VALLEY AND MESAS BETWEEN SUNSET AND 06Z AND THE WESTERN INLAND VALLEY AREAS BETWEEN MIDNIGHT AND 10Z. STRATUS IS NOT EXPECTED TO REACH KONT TONIGHT BUT COULD GET TO KCNO. ABOVE THE MARINE LAYER...EXCEPT FOR SOME AFTERNOON CU/TCU OVER THE MOUNTAINS DURING THE AFTERNOONS...A MOSTLY CLEAR SKY WITH UNRESTRICTED VISIBILITIES WILL CONTINUE THROUGH SATURDAY. MID AND HIGH LEVEL MOISTURE MOVING IN FROM THE SOUTHEAST ON SUNDAY COULD BRING TSTMS TO THE MOUNTAINS AND DESERTS ON SUNDAY. MAX TEMPS FOR KPSP AND KTRM FOR TODAY AND SAT...42 TO 44C. HORTON && .MARINE... A MODERATE SOUTH SWELL WILL BEGIN TO MOVE INTO THE COASTAL AREAS TODAY...INCREASING THROUGH SUNDAY. THE PERIOD WILL INCREASE TO 19 SECONDS ON SATURDAY WITH THE PEAK OF THE SWELL EXPECTED ON SUNDAY WITH A PERIOD DROPPING TO 16 SECONDS BY SUNDAY AFTERNOON. SURF IS FORECAST TO BE UP TO 3 TO 6 FEET ON SATURDAY WITH SETS TO 7 FEET OR HIGHER MAINLY IN ORANGE COUNTY SUNDAY. THERE WILL BE STRONG AND DANGEROUS RIP CURRENTS DURING THE WEEKEND. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC/FIRE WEATHER...BALFOUR AVIATION/MARINE...HORTON NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
920 AM PDT THU JUL 17 2008 .UPDATE...INCLUDED A SLIGHT CHANCE OF THUNDERSTORMS OVER THE VENTURA AND LOS ANGELES COUNTY MOUNTAINS AS WELL AS THE ANTELOPE VALLEY FOR THIS AFTERNOON THROUGH EARLY EVENING. IT IS LIKELY THUNDERSTORMS WILL NOT DEVELOP OVER THE AREA THOUGH WITH LIGHT NORTH FLOW OVER THE AREA STORMS THAT MAY DEVELOP IN THE UPPER DESERT AND TEHACHAPI RANGE WILL MOVE SOUTH OVER THE AREA. OTHERWISE HAVE INCLUDED HAZY SKIES OVER THE NORTH HALF OF THE AREA. SMOKE FROM THE MONTEREY COUNTY FIRES WILL CONTINUE TO DRIFT SOUTH TODAY AND TONIGHT. FOLLOWING DISCUSSION FROM PREVIOUS SHIFT... && .SHORT TERM... MARINE LAYER SITS AT ABOUT 800 FT. MARINE LAYER CLOUDS ARE ABOUT HALF WAY UP ORANGE COUNTY AND WILL LIKELY MAKE IT TO THE LA COAST BY DAWN. MARINE CLOUDS WELL ENTRENCHED ALONG THE CENTRAL COAST BUT THEY WILL BURN OFF. WITH 592 DM HGTS OVERHEAD TEMPS WILL RISE SLIGHTLY EVERYWHERE. TEMPS WILL BE A FEW DEGREES ABOVE NORMAL INLAND BUT THE MARINE LAYER WILL KEEP THINGS COOL AT THE COAST. ABOUT A 3 MB GRADIENT WILL SET UP BETWEEN SMX AND SBA WHICH SHOULD BE ENOUGH TO KICK UP SOME GUSTS TO 35 MPH ACROSS THE SBA SOUTH COAST AND FOOTHILLS. SOME LOW TO MID LEVEL NORTH FLOW WILL KICK UP SOME 15 TO 30 MPH WINDS THROUGH THE I-5 CORRIDOR AS WELL. A BETTER SLIGHTLY DEEPER MARINE LAYER IS FORECAST TONIGHT AND SHOULD MAKE IT INTO THE VENTURA COAST. HIGH HGTS WILL MOST LIKELY KEEP IT SMOOSHED OUT OF THE VTA/LA MTNS BUT CANNOT COMPLETELY RULE OUT A SAN GABRIEL PENETRATION. THE CENTRAL COAST WILL CONTINUE BLANKETED WITH CLOUDS. BURN OFF WILL BE COMPLETE FRIDAY MORNING BUT THE INVERSION WILL BE HIGH ENOUGH TO ALLOW A LITTLE COOL AIR INTO THE VALLEYS. THE ONSHORE PUSH IS GREATER BOTH N AND E AND EXPECT THIS TO COOL BOTH COASTS AND VLYS. MTNS/DESERTS WILL REMAIN ABV NORMAL. A LITTLE WEAK SUNDOWNER AS GRADIENTS RELAX ABOUT A HALF MILLIBAR. A FEW GUSTS TO 30 MPH THROUGH THE I5 CORRIDOR AS WELL. MARINE LAYER FORECAST IS VERY SIMILAR TO FRIDAY ON SATURDAY...EXCEPT THE SOUTH SBA COAST WILL LIKELY SEE SOME CLOUDS. THE UPPER HIGH PUSHES OFF TO THE EAST AND THE LOWER HGTS WILL ALLOW A FEW MORE DEGREES OF COOLING EVERYWHERE. THERE DOES NOT LOOK LIKE THERE IS ENOUGH UPPER SUPPORT FOR ANY SIGNIFICANT WINDS. .LONG TERM... GFS/ EC / GFS ENSEMBLES ARE FAIRLY SIMILAR ALL SHOWING THERE IS GOING TO BE A VERY STATIC PATTERN OVER THE WEST. THE WEATHER DOMINATED BY LARGE 4 CORNERS HIGH. THERE WILL BE NIGHT THROUGH MORNING LOW CLOUD PATTERN EVERYDAY AT THE COASTS BUT MOST LIKELY NOT THE VLYS. TEMPS WILL BE NEAR NORMAL AT THE COASTS BUT ABOVE NORMAL INLAND. BIG QUESTION IS THE MONSOON. SUNDAY LOOKS LIKE THE MOST WORRISOME DAY WITH A FEW MDLS SHOWING A GOOD MOISTURE PUSH. RIGHT NOW THOUGH IT LOOKS LIKE AFTERNOON AND EVENING CONVECTION WILL STAY TO THE SOUTH AND EAST OF THE AREA. THE MDLS ARE VERY POOR AT HANDLING THIS AND THIS IS THE MOST LIKELY PART OF THE FORECAST TO CHANGE. && .AVIATION... 17/1000Z. LATEST ACARS SOUNDING NEAR LAX HAD MARINE LAYER ABOUT 600 FT DEEP THIS MORNING. FOG PRODUCT SATELLITE IMAGERY KEEPS LIFR/IFR ACROSS THE CENTRAL COAST...WHILE AREAS S OF POINT CONCEPTION ONLY INDICATE PATCHY STRATUS JUST TO THE SOUTH OF LA COUNTY COASTAL AREAS THIS MORNING. CATALINA EDDY CONTINUES TO SPIN UP STRATUS THROUGH ORANGE COUNTY AND COULD BRING MVFR CIGS TO KLGB AND KLAX NEAR SUNRISE. MODERATE CONFIDENCE THAT THIS WILL OCCUR. IF LOW CLOUDS DO SPREAD INTO LA COUNTY...WILL ONLY AFFECT THE COASTAL AREAS OF LA COUNTY. EXPECT STRATUS ALONG THE CENTRAL COAST TO BURNOFF BY 17-18Z WITH VFR CONDS WHILE PATCHY MVFR CIGS ACROSS THE LA COUNTY COAST SHOULD BURNOFF BY 16Z...THEN VFR CONDS. SUNDOWNER CONDS WILL SET UP ACROSS SRN SBA COUNTY WHICH SHOULD CAUSE SOME UDDF AND LLWS NEAR KSBA FROM LATE THIS AFTERNOON THROUGH LATE NIGHT HOURS. MONSOONAL MOISTURE SHOULD SHIFT FARTHER EAST LEAVING ONLY A FEW CU BUILD-UPS ACROSS THE LA COUNTY MTNS THIS AFTERNOON. KLAX...MODERATE CONFIDENCE THAT MVFR CIGS WILL REACH THE AIRFIELD BY SUNRISE WITH BURNOFF BY 16-17Z. OTHERWISE HIGH CONFIDENCE VFR CONDS WILL PERSIST THROUGH AT LEAST 06Z. KBUR...HIGH CONFIDENCE FOR VFR CONDS THROUGH THIS EVENING. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXCWFLOX). && $$ PUBLIC...30/RORKE AVIATION...KAPLAN WWW.WEATHER.GOV/LOSANGELES
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
240 AM PDT THU JUL 17 2008 .SHORT TERM... MARINE LAYER SITS AT ABOUT 800 FT. MARINE LAYER CLOUDS ARE ABOUT HALF WAY UP ORANGE COUNTY AND WILL LIKELY MAKE IT TO THE LA COAST BY DAWN. MARINE CLOUDS WELL ENTRENCHED ALONG THE CENTRAL COAST BUT THEY WILL BURN OFF. WITH 592 DM HGTS OVERHEAD TEMPS WILL RISE SLIGHTLY EVERYWHERE. TEMPS WILL BE A FEW DEGREES ABOVE NORMAL INLAND BUT THE MARINE LAYER WILL KEEP THINGS COOL AT THE COAST. ABOUT A 3 MB GRADIENT WILL SET UP BETWEEN SMX AND SBA WHICH SHOULD BE ENOUGH TO KICK UP SOME GUSTS TO 35 MPH ACROSS THE SBA SOUTH COAST AND FOOTHILLS. SOME LOW TO MID LEVEL NORTH FLOW WILL KICK UP SOME 15 TO 30 MPH WINDS THROUGH THE I-5 CORRIDOR AS WELL. A BETTER SLIGHTLY DEEPER MARINE LAYER IS FORECAST TONIGHT AND SHOULD MAKE IT INTO THE VENTURA COAST. HIGH HGTS WILL MOST LIKELY KEEP IT SMOOSHED OUT OF THE VTA/LA MTNS BUT CANNOT COMPLETELY RULE OUT A SAN GABRIEL PENETRATION. THE CENTRAL COAST WILL CONTINUE BLANKETED WITH CLOUDS. BURN OFF WILL BE COMPLETE FRIDAY MORNING BUT THE INVERSION WILL BE HIGH ENOUGH TO ALLOW A LITTLE COOL AIR INTO THE VALLEYS. THE ONSHORE PUSH IS GREATER BOTH N AND E AND EXPECT THIS TO COOL BOTH COASTS AND VLYS. MTNS/DESERTS WILL REMAIN ABV NORMAL. A LITTLE WEAK SUNDOWNER AS GRADIENTS RELAX ABOUT A HALF MILLIBAR. A FEW GUSTS TO 30 MPH THROUGH THE I5 CORRIDOR AS WELL. MARINE LAYER FORECAST IS VERY SIMILAR TO FRIDAY ON SATURDAY...EXCEPT THE SOUTH SBA COAST WILL LIKELY SEE SOME CLOUDS. THE UPPER HIGH PUSHES OFF TO THE EAST AND THE LOWER HGTS WILL ALLOW A FEW MORE DEGREES OF COOLING EVERYWHERE. THERE DOES NOT LOOK LIKE THERE IS ENOUGH UPPER SUPPORT FOR ANY SIGNIFICANT WINDS. .LONG TERM... GFS/ EC / GFS ENSEMBLES ARE FAIRLY SIMILAR ALL SHOWING THERE IS GOING TO BE A VERY STATIC PATTERN OVER THE WEST. THE WEATHER DOMINATED BY LARGE 4 CORNERS HIGH. THERE WILL BE NIGHT THROUGH MORNING LOW CLOUD PATTERN EVERYDAY AT THE COASTS BUT MOST LIKELY NOT THE VLYS. TEMPS WILL BE NEAR NORMAL AT THE COASTS BUT ABOVE NORMAL INLAND. BIG QUESTION IS THE MONSOON. SUNDAY LOOKS LIKE THE MOST WORRISOME DAY WITH A FEW MDLS SHOWING A GOOD MOISTURE PUSH. RIGHT NOW THOUGH IT LOOKS LIKE AFTERNOON AND EVENING CONVECTION WILL STAY TO THE SOUTH AND EAST OF THE AREA. THE MDLS ARE VERY POOR AT HANDLING THIS AND THIS IS THE MOST LIKELY PART OF THE FORECAST TO CHANGE. && .AVIATION... 17/1000Z. LATEST ACARS SOUNDING NEAR LAX HAD MARINE LAYER ABOUT 600 FT DEEP THIS MORNING. FOG PRODUCT SATELLITE IMAGERY KEEPS LIFR/IFR ACROSS THE CENTRAL COAST...WHILE AREAS S OF POINT CONCEPTION ONLY INDICATE PATCHY STRATUS JUST TO THE SOUTH OF LA COUNTY COASTAL AREAS THIS MORNING. CATALINA EDDY CONTINUES TO SPIN UP STRATUS THROUGH ORANGE COUNTY AND COULD BRING MVFR CIGS TO KLGB AND KLAX NEAR SUNRISE. MODERATE CONFIDENCE THAT THIS WILL OCCUR. IF LOW CLOUDS DO SPREAD INTO LA COUNTY...WILL ONLY AFFECT THE COASTAL AREAS OF LA COUNTY. EXPECT STRATUS ALONG THE CENTRAL COAST TO BURNOFF BY 17-18Z WITH VFR CONDS WHILE PATCHY MVFR CIGS ACROSS THE LA COUNTY COAST SHOULD BURNOFF BY 16Z...THEN VFR CONDS. SUNDOWNER CONDS WILL SET UP ACROSS SRN SBA COUNTY WHICH SHOULD CAUSE SOME UDDF AND LLWS NEAR KSBA FROM LATE THIS AFTERNOON THROUGH LATE NIGHT HOURS. MONSOONAL MOISTURE SHOULD SHIFT FARTHER EAST LEAVING ONLY A FEW CU BUILD-UPS ACROSS THE LA COUNTY MTNS THIS AFTERNOON. KLAX...MODERATE CONFIDENCE THAT MVFR CIGS WILL REACH THE AIRFIELD BY SUNRISE WITH BURNOFF BY 16-17Z. OTHERWISE HIGH CONFIDENCE VFR CONDS WILL PERSIST THROUGH AT LEAST 06Z. KBUR...HIGH CONFIDENCE FOR VFR CONDS THROUGH THIS EVENING. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXCWFLOX). && $$ PUBLIC...RORKE AVIATION...KAPLAN WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS DENVER CO
305 PM MDT FRI JUL 18 2008 .SHORT TERM...CONVECTION CURRENTLY CONFINED TO MOUNTAINS...FOOTHILLS AND PALMER DIVIDE AS SHOWN BY LATEST RADAR. WATER VAPOR LOOPS SHOW SHORTWAVE OVER WESTERN COLORADO...CURRENTLY MORE DIFFUSE THAN EARLIER LOOPS SHOWN. ACROSS PLAINS...AIRMASS CAPPED FROM EARLIER SURGE WHICH MOVED ACROSS AREA. CURRENT LAPS SURFACE ANALYSIS AND ACARS SOUNDINGS SHOWING LARGE AREA OF CIN...THOUGH CAPES HAVE INCREASED TO OVER 1000 J/KG. WAVE TO MOVE ACROSS REMAINDER OF CWA THIS EVENING...THOUGH MOST OF THE CONVECTION SHOULD OCCUR OVER AREAS SOUTH OF INTERSTATE 70. AS FOR PLAINS...SHORTWAVE MAY BE ENOUGH TO BREAK CAP AND INITIATE CONVECTION ONCE IT MOVES ACROSS AREA. WILL KEEP THE HIGHER POPS ALONG PALMER DIVIDE AND LINCOLN COUNTY. STILL SOME POTENTIAL FOR A FEW SEVERE STORMS EAST OF A FORT MORGAN TO KIOWA LINE WHERE DEWPOINTS CURRENTLY HOVER IN THE 50S. HAIL AND STRONG OUTFLOW WIND THE MAIN THREATS. INTEGRATED PRECIPITABLE WATER VALUES CURRENTLY AROUND NINE TENTHS OF AN INCH...SO HEAVY RAIN STILL A POSSIBILITY. AS WAVE MOVES EAST OF AREA DURING THE EVENING...DRIER AIR WILL MOVE IN FROM THE WEST. AS A RESULT...SHOULD SEE SKIES CLEAR AROUND MIDNIGHT. BOUNDARY LAYER WIND AND HUMIDITY PROGS INDICATE POTENTIAL FOR SOME STRATUS AND PERHAPS FOG ACROSS THE FAR NORTHEAST PLAINS AFTER MIDNIGHT...THOUGH DOESN`T SEEM TO BE ENOUGH TO MAKE MUCH OF IMPACT. ON SATURDAY...UPPER LEVEL RIDGE BUILDS OVER REGION...WITH HOT AND DRY CONDITIONS RETURNING. MODEL CROSS SECTIONS SHOW MOST OF MOISTURE BEING SUPPRESSED SOUTH OF THE AREA...WITH SOME MID LEVEL MOISTURE ALONG THE EXTREME SOUTHERN REGIONS OF CWA. DAYTIME HEATING TO PROVIDE ENOUGH INSTABILITY...WHICH COULD POP A FEW AFTERNOON STORMS ALONG THE HIGHER TERRAIN SOUTH OF INTERSTATE 70. ALREADY LOW POPS IN THAT AREA...WILL CONTINUE FOR THIS PACKAGE. LATEST TEMPERATURE AND THICKNESS PROGS AS WELL AS GUIDANCE SUGGEST HIGHS IN THE 90S ACROSS THE PLAINS. CURRENT TEMPERATURE GRIDS IN LINE WITH GUIDANCE...AND LOOKS REASONABLE. .LONG TERM...HOT AND DRY CONDITIONS WILL REMAIN IN PLACE THROUGH SUNDAY. WOULD NOT BE SURPRISED TO SEE A FEW SPOTS ON THE PLAINS INCLUDING DENVER REACH THE CENTURY MARK GIVEN 700 MB TEMPS AROUND 20C. THE ONLY THREAT OF CONVECTION WOULD BE CONFINED TO THE HIGH COUNTRY WHERE A BIT OF MONSOONAL MOISTURE TRIES TO SNEAK INTO THE AREA BY LATE IN THE DAY. THESE WOULD PRODUCE ONLY VERY LIGHT RAINFALL BUT STRONG GUSTY WINDS. THE FORECAST PATTERN REMAINS LARGELY UNCHANGED THROUGH MOST OF NEXT WEEK WITH THE UPPER LEVEL HIGH WAFFLING OVER THE CENTRAL ROCKIES AND SOUTHERN HIGH PLAINS. HOWEVER...THIS GENERAL POSITION SHOULD ALLOW MONSOONAL MOISTURE BETTER AND MORE PERSISTENT ACCESS TO AT LEAST WESTERN AND CENTRAL COLORADO. WILL INCREASE POPS JUST A TAD MORE OVER THE MOUNTAINS WHILE ON THE PLAINS AIRMASS WILL AVERAGE DRIER AND MORE STABLE THROUGH THE PERIOD. AS A RESULT...THE LIMITED 10-20% POPS SHOULD SUFFICE OVER THE PLAINS FOR NOW WITH BETTER CHANCES OF RAIN LIKELY HOLDING OFF UNTIL LATER IN THE WEEK. TEMPERATURES WILL STILL AVERAGE SEVERAL DEGREES ABOVE NORMAL. && .AVIATION...SCATTERED THUNDERSTORMS EXPECTED THROUGH 04Z...WITH GUSTY OUTFLOW WINDS TO 40 KTS THE MAIN THREAT. A FEW STORMS COULD PRODUCE HEAVY RAIN. VFR CONDITIONS TO PREVAIL. SOME LOW CLOUDS TO DEVELOP ACROSS FAR EASTERN PLAINS BETWEEN 09Z AND 15Z...SHOULD BE WELL EAST OF THE DIA. DRY AIR OVER AREA SATURDAY. SLIGHT CHANCE OF THUNDERSTORMS AFTER 18Z ALONG THE SOUTHERN FOOTHILLS...SHOULD NOT HAVE ANY AFFECT ON LOCAL AIRPORTS. && .BOU WATCHES/WARNINGS/ADVISORIES...NONE. && D-L/BARJENBRUCH
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
613 PM CDT FRI JUL 18 2008 .DISCUSSION... 403 PM CDT FORECAST PROBLEM IS MAGNITUDE OF SHRA AND TS THREAT TONIGHT AND SAT...AS WELL AS POTENTIAL FOR SIGNIFICANT RAINFALL. A WEAK SURFACE BOUNDARY HAS BEEN LOCATED ACROSS FAR NORTHERN IL ALL DAY...WHILE A LAKE ENHANCED OUTFLOW HAS SETTLED INTO FAR NE IL. DEW POINTS HAVE BEEN POOLING S OF THESE BOUNDARIES WITH 20Z READINGS IN THE LOWER 70S COMMON. CAP THAT HAD BEEN IN PLACE ACROSS THE FA THE LAST COUPLE DAYS IN NOW MARGINAL OR NON EXISTENT BASED ON ACARS TEMP PROFILES ALLOWING SCT SHRA AND ISOLD TS TO DEVELOP BETWEEN 19Z AND 20Z AS SURFACE TEMPS REACHED MID 80S TO LOWER 90S. WITH MID LEVELS WARMER POSITIVE AREA NOT AS LARGE SO DO NOT EXPECT EXCESSIVELY VIGOROUS UPDRAFTS THOUGH WITH PRECIPITABLE WATER VALES APPROACHING 2 INCHES CONVECTIVE CELLS LIKELY TO BE EFFICIENT RAINFALL PRODUCERS. GFS AND NAM MODELS HAVE CAUGHT ON TO THE PRESENCE OF BOTH A COMPACT MID LEVEL LOW ON THE FAR EASTERN NE-KS BORDER...AS WELL AS AN H8 CIRCULATION IN FAR NW MO PER PROFILER AND 88D NETWORKS ALONG WITH SATELLITE DERIVED WINDS. THESE MODELS MOVE THE MID LEVEL LOW NE TO EASTERN IA BY 06Z SAT AND CONTINUE LIFTING ACROSS NW IL TO SOUTHERN WI DURING SAT MORNING. ENHANCED LOW LEVEL CONVERGENCE ACROSS NORTHERN IL AHEAD OF THE LOW LEVEL CIRCULATION AS WELL AS INCREASING UVV AS THE MID LEVEL FEATURE CONTINUES TO APPROACH FROM THE W. THIS EXPECTED TO CONTINUE DEVELOPMENT OF SHRA AND TS ACROSS NE MO AND SE IA ACROSS NORTHERN IL TONIGHT. DO NOT ANTICIPATE EXCESSIVE TRAINING OF CELLS BUT ONLY LOCALLY HEAVY DOWNPOURS SO NO FLASH FLOOD/FLOOD WATCHES ISSUED AT THIS TIME. CONTINUED CHANCES OF SHRA AND TS INTO SAT AFTERNOON AS MID LEVEL TROF SLOWLY PROGRESSES EASTWARD TO SOUTHERN LK MI BY 00Z SUN. SOME UNCERTAINTIES FOR SAT NIGHT THRU MON NIGHT WITH PROSPECTS FOR MORE RAIN. OPERATIONAL GFS FITS WELL WITH GFS ENSEMBLE MEAN IN BRINGING A SHORT WAVE ESE ACROSS THE UPPER MS VALLEY AND ACROSS SOUTHERN WI AND NORTHERN IL SAT NIGHT AND SUN MORNING WHILE NAM HAS AXIS OF QPF FAR REMOVED TO THE N ACROSS FAR NORTHERN WI AND THE U.P. OF MI. ECMWF AND UKMET ALSO SHOW THE MORE SOUTHERN TRACK SO GIVEN MAJORITY OF SOLUTIONS BRINGING RAIN ACROSS THE FA SAT NIGHT INTO SUN WILL MAINTAIN CHC POPS AS UPPER TROF DEVELOPS OVER THE GRTLKS AND LIKELY TO SEE PERIODIC IMPULSES ROTATING SE ACROSS THE UPPER MIDWEST AND INTO THE WESTERN LAKES. TRS && .AVIATION... 0000 UTC TAFS...VERY MESSY...WEAK GRADIENT...TYPICAL SUMMER PATTERN OVER THE AREA. THE WEAK FRONTAL BOUNDARY REMAINS NORTH OVER WISCONSIN WITH WARM...UNSTABLE WARM SECTOR AIR OVER NRN ILLINOIS/INDIANA. SCATTERED TS DEVELOPED OVER NERN IL DURG THE LATE AFTERNOON HOURS AND HAS LAID DOWN NUMEROUS OUTFLOW BOUNDARIES...CAUSING WIND DIRECTIONS TO BECOME VARIABLE AND CHANGABLE OVER THE FIRST FEW HOURS OF THE NEW TAF PERIOD. AS THE CONVERCTION REMAINS SCATTERED...CAN ONLY GO WITH A VCTS GROUP FOR THE TAFS AS THE LIKELYHOOD OF TS HITTING A TERMINAL IS SMALL. THE OTHER CONCERN IS A BATCH OF PCPN OVER SERN IOWA...MOVING INTO NWRN ILLINOIS. THIS PCPN WILL MOST LIKELY IMPACT THE RFD TERMINAL...BUT GIVEN THE WEAK STEERING FLOW...THERE IS STILL ACHANCE THAT PCPN COULD MOVE INTO THE ERN TERMINALS...OR IT COULD TRACK MORE NORTH INTO SRN WISCONSIN. BASED ON LATEST RADAR AND SATELLITE TRENDS...FEEL THERE IS A GOOD ENOUGH CHANCE FOR WETTING RAIN AT THE TERMINALS TO INCLUDE PREVAILING SHRA FOR THE EARLY MORNING HOURS. IN THE ABSENSE OF AN UPSTREAM KICKER TO PUSH THE PATTERN ALONG...FEEL THAT TOMORROW WILL BE VERY MUCH LIKE TODAY. THE AIRMASS OVER THE REGION WILL REMAIN WARM...HUMID AND UNSTABLE. SCT SHRA/TSRA WILL BE LIKELY...BUT PINPOINTING TS AT A TERMINAL IS DIFFICULT. WITH THE WEAK GRADIENT IN PLACE...WIDESPREAD MVFR VIS IN HZ/BR SHOULD DEVELOP IN THE EARLY MORNING HOURS GIVEN THE MOISTURE IN PLACE AND LIGHT TO CALM WINDS. KREIN && .MARINE... 1245 PM CDT STILL REMAINING IN A WEAK LOW PATTERN EXTENDING FROM EAST ONTARIO BACK SW TO THE NRN PLAINS. A FRONTAL BOUNDARY EXTENDING WEST FROM THE FIRST LOW PRESSURE IN ONTARIO WILL SAG SOUTH TONIGHT...SETTING UP NORTHEAST WINDS ACROSS THE NORTHERN HALF OF LAKE MICHIGAN TONIGHT. THE FRONT SHUD STALL OVER THE SOUTHERN HALF OF LAKE MICHIGAN SATURDAY. THEN A SECOND LOW PRESSURE AREA WILL DEEPEN ALONG THIS FRONT SATURDAY NIGHT AND TRACK ACROSS SOUTHERN LAKE MICHIGAN. THIS ALLOWS THE FRONT TO DROP SOUTH OF THE LAKE ON SUNDAY. NORTHWEST WINDS ARE EXPECTED ACROSS LAKE MICHIGAN SUNDAY WITH WEAK FLOW LEAVING SPEEDS OF ONLY 10 KNOTS OR LESS. WIND DIRECTIONS FOR THE EARLY PART OF NEXT WEEK CONFLICT WITH MODEL GUIDANCE WITH REGARDS TO LOCATION AND INTENSITY OF SURFACE HIGH MOVING INTO THE WESTERN GREAT LAKES. FOR NOW HAVE CONTINUED IDEA OF MAINTAINING WEST WINDS MON AND TUE AS RIDGE SLOWLY BUILDS INTO THE WESTERN GREAT LAKES. THE WEAK SURFACE GRADIENT ACROSS THE AREA SHOULD NOT PROMOTE MUCH WAVE ACTION WITH GENERALLY 2 FEET OR LESS FROM TONIGHT THROUGH THE EARLY PART OF NEXT WEEK. RLB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
404 PM CDT FRI JUL 18 2008 .DISCUSSION... 403 PM CDT FORECAST PROBLEM IS MAGNITUDE OF SHRA AND TS THREAT TONIGHT AND SAT...AS WELL AS POTENTIAL FOR SIGNIFICANT RAINFALL. A WEAK SURFACE BOUNDARY HAS BEEN LOCATED ACROSS FAR NORTHERN IL ALL DAY...WHILE A LAKE ENHANCED OUTFLOW HAS SETTLED INTO FAR NE IL. DEW POINTS HAVE BEEN POOLING S OF THESE BOUNDARIES WITH 20Z READINGS IN THE LOWER 70S COMMON. CAP THAT HAD BEEN IN PLACE ACROSS THE FA THE LAST COUPLE DAYS IN NOW MARGINAL OR NON EXISTENT BASED ON ACARS TEMP PROFILES ALLOWING SCT SHRA AND ISOLD TS TO DEVELOP BETWEEN 19Z AND 20Z AS SURFACE TEMPS REACHED MID 80S TO LOWER 90S. WITH MID LEVELS WARMER POSITIVE AREA NOT AS LARGE SO DO NOT EXPECT EXCESSIVELY VIGOROUS UPDRAFTS THOUGH WITH PRECIPITABLE WATER VALES APPROACHING 2 INCHES CONVECTIVE CELLS LIKELY TO BE EFFICIENT RAINFALL PRODUCERS. GFS AND NAM MODELS HAVE CAUGHT ON TO THE PRESENCE OF BOTH A COMPACT MID LEVEL LOW ON THE FAR EASTERN NE-KS BORDER...AS WELL AS AN H8 CIRCULATION IN FAR NW MO PER PROFILER AND 88D NETWORKS ALONG WITH SATELLITE DERIVED WINDS. THESE MODELS MOVE THE MID LEVEL LOW NE TO EASTERN IA BY 06Z SAT AND CONTINUE LIFTING ACROSS NW IL TO SOUTHERN WI DURING SAT MORNING. ENHANCED LOW LEVEL CONVERGENCE ACROSS NORTHERN IL AHEAD OF THE LOW LEVEL CIRCULATION AS WELL AS INCREASING UVV AS THE MID LEVEL FEATURE CONTINUES TO APPROACH FROM THE W. THIS EXPECTED TO CONTINUE DEVELOPMENT OF SHRA AND TS ACROSS NE MO AND SE IA ACROSS NORTHERN IL TONIGHT. DO NOT ANTICIPATE EXCESSIVE TRAINING OF CELLS BUT ONLY LOCALLY HEAVY DOWNPOURS SO NO FLASH FLOOD/FLOOD WATCHES ISSUED AT THIS TIME. CONTINUED CHANCES OF SHRA AND TS INTO SAT AFTERNOON AS MID LEVEL TROF SLOWLY PROGRESSES EASTWARD TO SOUTHERN LK MI BY 00Z SUN. SOME UNCERTAINTIES FOR SAT NIGHT THRU MON NIGHT WITH PROSPECTS FOR MORE RAIN. OPERATIONAL GFS FITS WELL WITH GFS ENSEMBLE MEAN IN BRINGING A SHORT WAVE ESE ACROSS THE UPPER MS VALLEY AND ACROSS SOUTHERN WI AND NORTHERN IL SAT NIGHT AND SUN MORNING WHILE NAM HAS AXIS OF QPF FAR REMOVED TO THE N ACROSS FAR NORTHERN WI AND THE U.P. OF MI. ECMWF AND UKMET ALSO SHOW THE MORE SOUTHERN TRACK SO GIVEN MAJORITY OF SOLUTIONS BRINGING RAIN ACROSS THE FA SAT NIGHT INTO SUN WILL MAINTAIN CHC POPS AS UPPER TROF DEVELOPS OVER THE GRTLKS AND LIKELY TO SEE PERIODIC IMPULSES ROTATING SE ACROSS THE UPPER MIDWEST AND INTO THE WESTERN LAKES. TRS && .AVIATION... 1800 UTC TAFS...VFR CONDS PREVAILING WITH MAIN FOCUS OF CONCERN ON TSTM DEVELOPMENT. TIMING IS FIRST QUESTION. ANALYSIS WUD INDICATE A WEAK DIFFUSE TROF FROM GRB AREA SW TO MKC. BUT OUTFLOW BOUNDARIES LAY ACROSS AREA FROM LAST NIGHTS CONVECTIVE OUTFLOWS WHICH ARE PROBABLY RESPONSIBLE FOR ENHANCING SHOWERS IN NE IL AT PRESENT. THIS CONVECTION IS NORTH OF OHARE AND PLAYING HAVOC WITH TAKEOFFS. THIS ALSO PRODUCING OUTFLOWS SEWD TWD OHARE WITH TEMPO WINDS FROM THE NW NEXT HOUR. WINDS HAVE PICKED UP BRISKLY FROM THE SW...ALTERING PLANS FROM EXPECTING LAKE BREEZE. YET WINDS DIMINISH WITH SUNSET TO L/V OR LITE SW. BASED ON DEWPT DEPRESSION FCST OVERNIGHT ALG WITH UPS FOG PROGRAM OUTPUT AND WEAKER WIND FLOW ...PROBABLE TO SEE MVFR FOG AFTER MIDNGT. THIS LIFTING SLOWLY SAT MRNG TO 6 IN HAZE FOR THE DAY...TURNING OUT TO BE A HOT HAZY HUMID SUMMER DAY. A MID LVL TROF APPROACHES OVERNIGHT AND HAVE INSERTED PROB30 FOR TSTMS AT RFD AFTER 09Z. HOWEVER PROSPECTS FOR ANY OVERNIGHT COMPLEX LOSING ENERGY IN THE PREDAWN HOURS TOO MUCH OF A TEMPTATION TO ADVECT STORMS ANY FURTHER EAST TO DPA OR ORD. SO HAVE NOT ATTEMPED EVEN A VCTS FOR TERMINALS EAST OF RFD. WILL TAKE A WAIT AND SEE APPROACH INSTEAD OF DISRUPTING AVIATION CONCERNS FOR SOMETHING LOSING LIKELIHOOD WITH TIME. RLB && .MARINE... 1245 PM CDT STILL REMAINING IN A WEAK LOW PATTERN EXTENDING FROM EAST ONTARIO BACK SW TO THE NRN PLAINS. A FRONTAL BOUNDARY EXTENDING WEST FROM THE FIRST LOW PRESSURE IN ONTARIO WILL SAG SOUTH TONIGHT...SETTING UP NORTHEAST WINDS ACROSS THE NORTHERN HALF OF LAKE MICHIGAN TONIGHT. THE FRONT SHUD STALL OVER THE SOUTHERN HALF OF LAKE MICHIGAN SATURDAY. THEN A SECOND LOW PRESSURE AREA WILL DEEPEN ALONG THIS FRONT SATURDAY NIGHT AND TRACK ACROSS SOUTHERN LAKE MICHIGAN. THIS ALLOWS THE FRONT TO DROP SOUTH OF THE LAKE ON SUNDAY. NORTHWEST WINDS ARE EXPECTED ACROSS LAKE MICHIGAN SUNDAY WITH WEAK FLOW LEAVING SPEEDS OF ONLY 10 KNOTS OR LESS. WIND DIRECTIONS FOR THE EARLY PART OF NEXT WEEK CONFLICT WITH MODEL GUIDANCE WITH REGARDS TO LOCATION AND INTENSITY OF SURFACE HIGH MOVING INTO THE WESTERN GREAT LAKES. FOR NOW HAVE CONTINUED IDEA OF MAINTAINING WEST WINDS MON AND TUE AS RIDGE SLOWLY BUILDS INTO THE WESTERN GREAT LAKES. THE WEAK SURFACE GRADIENT ACROSS THE AREA SHOULD NOT PROMOTE MUCH WAVE ACTION WITH GENERALLY 2 FEET OR LESS FROM TONIGHT THROUGH THE EARLY PART OF NEXT WEEK. RLB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1235 AM CDT THU JUL 17 2008 .DISCUSSION... 409 PM CDT IMMEDIATE CONCERN IS CONVECTIVE POTENTIAL IN SOUTHERN WI AND INTO FAR NORTHERN IL LATE THIS AFTERNOON AND FIRST PART OF THIS EVE. CU OVER THE FA AND SOUTHERN WI NOT SHOWING MUCH VERTICAL DEVELOPMENT IN VISIBLE SATELLITE SHOTS. THIS IS DUE TO THE CAP ACROSS THE AREA WHICH THE 12Z RAOBS FROM DVN AND ESPECIALLY ILX SHOWED...AND WHICH CONTINUES TO BE SEEN IN ACARS DATA FROM ORD AND MDW ARRIVALS AND DEPARTURES. THE ISOTHERMAL LAYER BETWEEN APPROXIMATELY 830MB AND 780MB HAS BEEN MAINTAINED SINCE THIS MORNING AND IS EVEN SEEN WELL TO THE W IN DATA FROM CID...THOUGH CAP NOT AS STRONG. WHILE SFC TEMPS IN THE UPPER 80S AND LOWER 90S ALONG WITH DEW POINTS IN THE UPPER 60S TO MID 70S YIELD VERY LARGE SBCAPE VALUES OF UP TO 5000 J/KG IN SE WI THERE IS NO LOW LEVEL FORCING MECHANISM AVAILABLE TO OVERCOME THE LOW LEVEL CIN RESULTING FROM THIS CAP. FURTHER N INTO WI THIS CAP IS NOT PRESENT THUS THE INTENSE CONVECTION THAT HAS BEEN ONGOING FOR SEVERAL HOURS NOW. THE ONLY POTENTIAL TRIGGER WOULD BE IF THE OUTFLOW FROM THE WI STORMS COULD CONTINUE TO PROGRESS S ACROSS THE BORDER. RATHER STUNG LOW LEVEL SW FLOW OF 15-25KTS IN THE LOWEST 1.5KM TO INHIBIT PROGRESS BUT INTENSIFYING COLD POOL COULD BE ENOUGH TO OVERCOME. THUS...HAS SLIGHT CHANCE POPS IN THE FAR NORTHERN TIER OF COUNTIES ALONG THE WI BORDER FOR THIS EVE. COMPACT MID LEVEL CIRCULATION THAT APPEARS TO HAVE BEEN GENERATED BY AN MCS IN NEB LAST NIGHT IS NOW MOVING OVER SW IA MOVING ENE. ONLY WEAK RADAR ECHOES NOTED WITH THIS FEATURE WITH SOME VERY LIGHT RAIN OF SPRINKLES REPORTED. MODELS SHOW THIS WAVE TO LIFT NE ACROSS NE IA TOWARD SE WI THIS EVE AND NOT EFFECT THE FA. FOR THU...ZONAL WESTERLIES REMAIN ALONG THE U.S.-CANADIAN BORDER WITH MULTIPLE SHORT WAVES RIDING W TO E. SURFACE BOUNDARY TO BE ACROSS SOUTHERN MN AND CENTRAL WI INTO NORTHERN LOWER MI WHICH IS WERE TS WILL BE FOCUSED. BY FRI MORNING A SHORT WAVE TROF WILL BE MOVING ACROSS THE UPPER MIDWEST WITH THE SURFACE FRONT SAGGING FURTHER S TOWARD THE FA. MID LEVEL FLOW REMAINS WSW-W ACROSS NORTHERN IL INTO FAR SOUTHERN WI SO FRONT TO ONLY MAKE SLOW PROGRESS SOUTHWARD SO POPS ONLY GRADUALLY INCREASE ACROSS THE NW AND N PORTIONS OF THE FA. ANOTHER SHORT WAVE TO APPROACH THE AREA ON SAT WITH THE COLD FRONT TO EVENTUALLY MOVE INTO THE NORTHERN PORTION OF THE FA THROUGH THE FA...BUT NOT PUSHING ALL THE WAY THROUGH AND INTO CENTRAL AND SOUTHERN IL UNTIL LATER SUN AS THE FLOW VEERS TO WNW. VERY WARM TO HOT DAYS AND MUGGY/HUMID CONDITIONS TO PERSIST UNTIL FRONT WORKS THROUGH. TRS && .AVIATION...DICUSSION REGARDING 06Z TAFS. 1235 AM CDT INFLUENCE OF OUTFLOW BOUNDARY/LAKE BREEZE INDUCED BY EARLIER TSTMS TO N OF TERMINALS HAS ALL BUT DISSIPATED. WINDS OVR MUCH OF NRN IL/NWRN IND HAVE TURNED LGT SELY AND TEMP/DEW POINTS HAVE CREPT BACK UP AS LARGER SCALE TRPCL AIR FILTERS BACK INTO RGN. MAIN CONCERN THIS FCST PERIOD WILL BE WHAT EFFECTS...IF ANY...THAT NEW TSTM CLUSTERS WILL HAVE THRU NXT 24 HRS. THESE STMS ARE EXPECTED TO FOCUS THEIR DVLPMT ALG SFC FRONT DRAPED FROM UPR GRTLKS...WWD TO NRN PLAINS. FRONTAL WAVE IS FCST TO MOVE ALG THIS BOUNDARY TODAY...AND BE LOCATED INVOF NWRN WI BY 06Z FRI. ATTM...MORE VIGOROUS NEW CONVECTION IS LOCATED OVR SD AT NOSE OF STGR LLVL SLY FLOW. ANVIL CANOPY FROM THESE STMS IS SPREADING DOWNSTREAM AND WILL LIKELY BE OVERSPREADING NRN IL LATER THIS MRNG BEFORE THINNING BY ERLY AFTN AS PARENT COMPLEX WEAKENS DIURNALLY. MORE WIDESPREAD NEW STMS DVLPG ALG FRONT THIS AFTN EXPECTED TO STAY WELL N OF AREA...PERHAPS BCMG A TRAFFIC PROBLEM ACROSS NW/N SECTORS OF ZAU...BUT ONLY SPREADING SOME VFR CLOUDINESS ACROSS NRN IL/NWRN IND. LOCALLY...WINDS WILL BE A MORE CERTAIN CONCERN TDY. LGT SLY FLOW TO START DAY WILL INCRS AND TURN SWLY AS SFC HEATS UP QUICKLY THIS MRNG AND ATMOSPHERE BEGINS TO MIX OUT BY LATE MRNG. INCRSG PRESSURE GRADIENT AND LWRG SFC PRESSURE ASSD WITH APCHG FRONTAL WAVE TO NW WILL HELP IN INCRSG WINDS TO NR 15 KTS BY AFTN...WITH MIXING CAUSING PERIOD OF AFTN GUSTINESS TO ABV 20 KTS. GUSTS WILL THEN SUBSIDE TWD SUNSET THIS EVENING. MERZLOCK && .MARINE... 1245 AM CDT A WEAK FRONTAL BOUNDARY EXTENDS FROM THE NORTHERN PLAINS...ACROSS THE CENTRAL PORTION OF LAKE MICHIGAN...TO LAKE HURON. THIS FRONT WILL LIFT ACROSS THE NORTHERN PART OF LAKE MICHIGAN TODAY AS A WAVE OF LOW PRESSURE DEVELOPS OVER THE NORTHERN PLAINS AND MOVES TO NORTHERN WISCONSIN BY FRIDAY MORNING. THIS FRONT WILL THEN SAG SOUTHWARD ACROSS THE LAKE AGAIN FRIDAY NIGHT INTO SATURDAY...ACCOMPANIED BY PERIODIC THUNDERSTORM CLUSTERS. RATHER DIFFUSE PRESSURE GRADIENT IS EXPECTED BEHIND THE FRONT...SO NO SIGNIFICANT WINDS/WAVES ARE EXPECTED IN THE POST FRONTAL AIR MASS THIS WEEKEND. MERZLOCK && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
254 PM EDT FRI JUL 18 2008 .SYNOPSIS... HIGH PRESSURE WILL MOVE INTO THE WESTERN ATLANTIC BY SATURDAY. A COLD FRONT WILL WORK ACROSS THE REGION MONDAY. TYPICAL SUMMER HEAT AND HUMIDITY WILL PREVAIL THROUGH THE PERIOD. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... WATER VAPOR LOOP SHOWS A RIDGE FROM THE SOUTHWEST CONUS EAST INTO THE MID ATLANTIC. A SYSTEM WAS OFF THE GEORGIA COAST...WITH THE MEAN FLOW RESIDING ALONG THE CANADIAN BORDER. ACARS 400-250MB WIND OBSERVATIONS SHOW A 80-120KT JET FROM THE PACIFIC NORTHWEST EAST NORTHEAST OVER THE UPPER GREAT LAKES AND NEW ENGLAND. LIGHT WINDS RESIDED OVER THE SOUTHEAST CONUS. 11Z SURFACE ANALYSIS PLACED A 1012MB CYCLONE OFF THE GEORGIA COAST. 1021MB ANTICYCLONE DOMINATED THE CENTRAL APPALACHIANS...WELL AHEAD OF THE COLD FRONT ACROSS THE UPPER MIDWEST. SUBSIDENCE WITH RIDGING ALOFT WILL YIELD DEEP MIXING WITH TEMPERATURES IN THE MIDDLE 90S THIS AFTERNOON. WHILE THE DEEP MIXING SHOULD MIX SOME DRIER AIR TO THE SURFACE...LOCALLY POOLING OF HIGHER DEWPOINTS NEAR THE CITIES AND ALONG THE WATER IS POSSIBLE. HEAT INDEX WILL NEAR 100F IN SOME LOCATIONS THROUGH THE REMAINDER OF THE AFTERNOON. EXPECT MID LEVEL CAP TO REMAIN IN TACT. DEEP MIXING IS ALLOWING DEWPOINTS TO FALL INTO THE 50S AND LOWER 60S WEST OF THE BLUE RIDGE. BELIEVE THIS WILL MEAN LESS OF A FOG THREAT TONIGHT COMPARED TO PREVIOUS NIGHTS...BUT A FEW AREAS MAY SEE PATCHY FOG...ESPECIALLY ALONG BLUE RIDGE...AND PERHAPS LOWER SOUTHERN MARYLAND AS HIGHER MOISTURE ADVECTS IN AHEAD OF CYCLONE OFF GEORGIA COAST. OTHERWISE CLEAR SKIES AND LIGHT WINDS PRESENT GOOD RADIATIONAL COOLING CONDITIONS...WITH TEMPERATURES COOLER THAN PREVIOUS NIGHTS ESPECIALLY OUT WEST. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY NIGHT/... WHILE CANT COMPLETELY RULE OUT ISOLATED CONVECTION SATURDAY AFTERNOON...POSITION BETWEEN WESTERLIES TO THE NORTH AND CYCLONE TO THE SOUTH SHOULD KEEP REGION IN SUBSISTENT ZONE. WITH TEMPERATURES SIMILAR TO TODAY...AND MOISTURE INCREASING FROM THE COAST AHEAD OF THE CYCLONE...HEAT INDEX VALUES MAY ONCE AGAIN NEAR 100F ALONG AND EAST OF INTERSTATE 95. BEST CUMULUS GROWTH EXPECTED ACROSS SOUTHEAST ZONES WITH RECOVERING MOISTURE...AND ALONG THE TERRAIN OUT WEST. CYCLONE OFF CAROLINA COAST WL BE THE WILD CARD IN THE SUN-MON FCST. NAM KEEPS IT WELL DEFINED...BUT CURVES IT NE INTO THE ATLC. GFS SOLN ABSORBS LOW ACRS CWFA INTO APPCHG CDFNT. OBVIOUSLY...NAM SOLN WUD BE MUCH DRIER FOR CWFA...AS AREA WUD BE IN RING OF SUBSIDENCE. UNTIL TRENDS CAN BE DETERMINED /IN 12-24 HRS/...WUD PREFER TO STAY REMAIN ON THE DRY ROAD. THAT/S NOT TO SAY THAT AN ISOL TSRA OR TWO CUDNT DVLP SUN...BUT CANNOT ADD VALUE IN TERMS OF ITS PLACEMENT. EITHER WAY...BY MON CDFNT SHUD BE NEARBY...AND THAT WUD PROVIDE A TRIGGER FOR TSRA DVLPMNT. WL TIE POPS TO THE DIURNAL CYCLE /AFTN- EVE/. MAXT WL BE TYPICAL FOR SUMMER...BUT SHUD BE EDGING DWN A CPL DEGF BY MON DUE TO ERODING HGTS/INCR CLDS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... WHAT TO DO W/ THE CDFNT REMAINS THE ISSUE THRU THE XTNDD FCST AS WELL. GFS DRIVES IT OFFSHR...BUT THEN BRINGS A POTENT WV ACRS WED. ECMWF MUCH SLOWER...KEEPING CDFNT ARND IN SHADOW OF H5 TROF AXIS. WL GO SOMEWHERE BTWN THE TWO. RDGG SHUD BE ABLE TO SHOVE BNDRY E/SE OF CWFA...ALLOWING ENUF DRY AIR TO ADVECT IN. AGN...THERE WL BE ENUF TYPICALL SUMMERTIME HEAT FOR DIURNALLY DRIVEN SHRA/TSRA. ATTM TUE AFTN/EVE LOOKS LIKE THE BEST BET. THEREAFTER...CONFIDENCE IN ANY ONE SOLN WANES CONSIDERABLY. SO...A DRY FCST WL RTN TIL TRENDS CAN BE DETERMINED. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... PATCHY FOG TONIGHT...MOST LIKELY NOT AS PREVENT AS PREVIOUS NIGHTS AS DEW POINTS MIX OUT THIS AFTERNOON. OTHERWISE CLEAR SKIES AND LIGHT SOUTHERLY WINDS THROUGH THE TAF PERIOD. LOCALLY...MTN/BWI ONSHORE FLOW SHOULD BACK TO LIGHT SOUTHERLY THIS EVENING...BEFORE REFORMING TOMORROW. MVFR-LCL IFR PSBL INVOF AFTN-EVE TSRA MON-TUE. && .MARINE... SOUTHERLY CHANNELING REGIME IS FORECAST TO DEVELOP LATER THIS AFTERNOON AND EVENING. WIND SPEEDS ARE FORECAST TO REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA AT THIS TIME. SOUTHWEST WINDS LATE TONIGHT BECOME SOUTHERLY AGAIN TOMORROW AFTERNOON. NO FLAGS XPCTD THRU END OF FCST PD. TRAJ SLY THRU SUN...AND MAY BRIEFLY INCR IN CHANNELING LT DAY-ELY EVE. AFTN-EVE TSRA MON-TUE INVOF CDFNT MAY BRING LCLLY HIER WNDS/WVS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...HTS NEAR TERM...ROGOWSKI SHORT TERM...ROGOWSKI/HTS LONG TERM...HTS AVIATION...ROGOWSKI/HTS MARINE...ROGOWSKI/HTS
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1213 PM CDT FRI JUL 18 2008 .AVIATION... /18Z TAFS - KABI...KSJT...KJCT...KSOA...KBBD/ VFR CONDITIONS WILL PREVAIL WITH VERY MINIMUL WEATHER IMPACTS EXPECTED TO AIRCRAFT OPERATIONS. WINDS WILL REMAIN SOUTH TO SOUTHEAST AT AROUND 10 KTS WITH SOME GUSTS OF 15 TO 20 KTS THIS AFTERNOON AT KABI...KSJT...AND KSOA BEFORE SUBSIDING AFTER 23Z. && .PREV DISCUSSION... /ISSUED 701 AM CDT FRI JUL 18 2008/ AVIATION... SHALLOW LOW LEVEL MOISTURE WILL NUDGE INTO THE INTERSTATE 10 CORRIDOR OVER THE NEXT COUPLE OF HOURS. OTHERWISE...SRLY WINDS WILL CONTINUE TODAY BUT NOT VERY STRONG AS FLOW IS ON THE WEAK SIDE FOR TODAY AND SAT. MOISTURE SHOULD INCREASE SOME AS WE GO THROUGH THE WEEKEND. 11/KEISER PREV DISCUSSION... /ISSUED 354 AM CDT FRI JUL 18 2008/ SHORT TERM... WATER VAPOR IMAGERY SHOWS THE MOISTURE ROTATING AROUND THE UPPER RIDGE LOCATED OVER THE ARIZONA/NEW MEXICO BORDER THIS MORNING. THE DEEP MOISTURE AXIS NOW RESIDES FROM THE CENTRAL PLAINS WITH THE ONGOING THUNDERSTORM ACTIVITY...SOUTHWESTWARD INTO SOUTHERN NEW MEXICO. MUCH OF TEXAS IS UNDER THE INFLUENCE OF MID AND UPPER LEVEL DRY AIR FILTERING IN FROM THE NORTHEAST. THIS HAS KEPT CLOUD COVERAGE MUCH LOWER THAN IN PREVIOUS NIGHTS. HOWEVER...THE CWFA IS STILL ON THE EASTERN PERIPHERY OF THE MOISTURE PLUME...SO LOW TO MID LEVEL CLOUDS WILL BE POSSIBLE ACROSS THE WESTERN PORTIONS OF THE FA...WITH LESS OVERALL COVERAGE THAN YESTERDAY. AFTERNOON HIGHS WILL BE IN THE MID TO UPPER 90S WITH FAIR TO PARTLY CLOUDY SKIES. DO EXPECT OVERNIGHT LOWS TOMORROW MORNING TO BE A FEW DEGREES COOLER WITH THE DRIER AIR IN PLACE. LONG TERM... MODEL GUIDANCE IN GOOD AGREEMENT ON LOCATION OF UPPER LEVEL HIGH PRESSURE SYSTEM THIS WEEKEND INTO NEXT WEEK. BOTH PROG THE RIDGE AXIS ACROSS THE INTER MOUNTAIN WEST BY SATURDAY PUTTING TEXAS IN NORTHEAST FLOW ALOFT. DO EXPECT THIS NORTHEAST FLOW TO SUPPRESS MUCH OF THE GULF MOISTURE FLOW INTO TEXAS...KEEPING THE FORECAST DRY THROUGH THE START OF NEXT WEEK. THE UPPER HIGH WILL THEN TRANSLATE EAST OVER THE CENTRAL PLAINS BY THE MIDDLE OF NEXT WEEK...BRINGING A RETURN THE ONSHORE FLOW OF GULF MOISTURE INTO THE REGION. BOTH THE ECMWF AND GFS ARE SUGGESTING THE TROPICAL WAVE LOCATED AROUND 70W IN THE CARIBBEAN TO MOVE INTO THE WESTERN GULF BY WEDNESDAY. HAVE INCREASED THE CLOUD COVER AND DECREASED TEMPS ACROSS OUR SOUTHERN COUNTIES TO ACCOUNT FOR THE ABUNDANT MOISTURE THE TROPICAL WAVE MAY BRING TO OUR CWFA. HOWEVER...HAVE NOT SIGNIFICANTLY INCREASED POPS AT THIS TIME. WILL CONTINUE TO MONITOR THE NHC/MODEL TRENDS WITH THIS TROPICAL WAVE AS INCREASED POPS MAY BE NECESSARY. OTHERWISE...EXPECTING TEMPS IN THE MID TO UPPER 90S ACROSS ALL WEST CENTRAL TEXAS THROUGH NEXT WEEK. THE EXCEPTION BEING ACROSS THE SOUTHERN COUNTIES WHERE TEMPS MAY BE LOWER IN THE LOW 90S FROM MONDAY THROUGH THE REST OF THE FORECAST. OVERNIGHT LOW WILL BE IN THE LOW TO MID 70S. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 71 96 72 96 / 0 10 10 10 SAN ANGELO 73 96 73 97 / 0 10 10 10 JUNCTION 72 95 72 96 / 0 10 0 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ LACY
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
530 AM EDT SAT JUL 19 2008 .SHORT TERM /TODAY THROUGH MONDAY/... TROPICAL DEPRESSION THREE JUST OFF THE GEORGIA AND SOUTH CAROLINA COASTS IS FORECAST TO STRENGTHEN TODAY WHILE IT CONTINUES TO DRIFT NORTHEASTWARD UP THE MID ATLANTIC COAST OVER THE WEEKEND. THE FORECAST AREA IS ON THE DRY...SUBSIDENT SIDE OF THE STORM...SO WILL ONLY SHOW A SLIGHT CHANCE OF CONVECTION OVER THE FAR SOUTHEAST REACHES OF THE FORECAST AREA TODAY...JUST INCASE A CONVECTIVE BAND MOVES INLAND DURING MAX HEATING. OTHERWISE...THE DRY SUBSIDENT AIR WILL ALLOW AFTERNOON TEMPS TO WARM INTO THE MID AND UPPER 90S FOR MUCH OF CENTRAL GEORGIA TODAY...LOWER 90S NORTH. THE WARM...DRY TREND WILL PERSIST THROUGH SUNDAY...THEN A RETURN FLOW SETS UP ON MONDAY WITH A WEAKNESS IN THE UPPER LEVELS...SUGGESTING A RETURN TO ISOLATED AFTERNOON CONVECTION ON MONDAY. AN INTERESTING NOTE...A WAVE CURRENTLY IN THE CENTRAL CARIBBEAN IS PROGD BY THE GFS TO STRENGTHEN AND PUSH INTO THE WESTERN GULF BY MONDAY AFTERNOON. WILL HAVE TO MONITOR THIS POTENTIAL CLOSELY OVER THE NEXT FEW DAYS. A HURRICANE HUNTER AIRCRAFT WILL FLY THE SYSTEM TODAY... AND PROVIDE VITAL ATMOSPHERIC DATA FOR LATER COMPUTER FORECAST MODEL RUNS. SO STAY TUNED. .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... A CONTINUED MOIST SOUTHERLY WIND FLOW COUPLED WITH A WEAKNESS IN THE UPPER LEVELS WILL SUPPORT ISOLATED AFTERNOON STORMS ON TUESDAY. AN APPROACHING FRONTAL BOUNDARY AND A DEEPER INFLUX OF TROPICAL MOISTURE WILL WARRANT A CHANCE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS FOR THURSDAY AND FRIDAY. CURRENTLY...THE GFS IS TAKING THE AFOREMENTIONED TROPICAL LOW INTO SOUTH TEXAS BY MID WEEK. SUGGEST ALL INTERESTS CONTINUE TO MONITOR THIS SYSTEM FOR THE NEXT SEVERAL DAYS. && .FIRE WEATHER... THE DRY SUBSIDENT AIR ON THE WEST SIDE OF TROPICAL DEPRESSION THREE WILL HELP AFTERNOON RH VALUES TO DIP INTO THE UPPER 20S AND LOWER 30S TODAY AND SUNDAY. OTHERWISE...NO CRITICAL FIRE WEATHER CONCERNS ARE ANTICIPATED OVER THE NEXT SEVERAL DAYS. && .AVIATION... TROPICAL LOW CENTER CONTINUES TO SPIN OFF THE SC COAST. THIS LOW CENTER IS CREATING HAVOC WITH THE WIND DIRECTION OVER THE AREA. WINDS ARE NE TO NW ACROSS THE AREA BUT THEY SHOULD ALL TURN MAINLY NW AS THE LOW CENTER TRACK NE ALONG THE EASTERN SEABOARD TODAY. WIND SPEEDS WILL BE NEAR CALM THIS MORNING INCREASING TO 5-10KT BY 18Z-20Z. THERE ARE SOME PATCHY AREAS OF RADIATION FOG THIS MORNING BUT NOT EXPECTING VSBYS TO GET LOWER THAN 5SM. ANY FOG THAT DEVELOPS WILL BURN OFF BY 13Z. EXPECTING SCATTERED CU FIELD TO BEGIN DEVELOPING ACROSS THE STATE BY 15-16Z WITH MOST AREAS SEEING SCT040-SCT060 BY 17Z. NO PRECIPITATION EXPECTED THROUGH THE PERIOD. && .PRELIMINARY POINT TEMPS/POPS... ATHENS 94 67 95 72 92 / 5 5 0 5 10 ATLANTA 92 72 93 73 90 / 5 5 5 5 10 BLAIRSVILLE 89 64 89 65 89 / 5 10 10 10 20 CARTERSVILLE 92 63 93 68 91 / 5 10 5 10 10 COLUMBUS 95 71 97 74 92 / 5 5 5 5 10 GAINESVILLE 91 69 94 70 90 / 5 10 5 5 20 MACON 96 68 98 72 97 / 10 5 0 5 10 ROME 94 65 95 70 93 / 5 10 10 10 10 PEACHTREE CITY 93 62 94 67 90 / 5 5 5 5 10 VIDALIA 97 74 97 70 97 / 20 10 0 5 20 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 39
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
331 AM EDT SAT JUL 19 2008 .SHORT TERM /TODAY THROUGH MONDAY/... TROPICAL DEPRESSION THREE JUST OFF THE GEORGIA AND SOUTH CAROLINA COASTS IS FORECAST TO STRENGTHEN TODAY WHILE IT CONTINUES TO DRIFT NORTHEASTWARD UP THE MID ATLANTIC COAST OVER THE WEEKEND. THE FORECAST AREA IS ON THE DRY...SUBSIDENT SIDE OF THE STORM...SO WILL ONLY SHOW A SLIGHT CHANCE OF CONVECTION OVER THE FAR SOUTHEAST REACHES OF THE FORECAST AREA TODAY...JUST INCASE A CONVECTIVE BAND MOVES INLAND DURING MAX HEATING. OTHERWISE...THE DRY SUBSIDENT AIR WILL ALLOW AFTERNOON TEMPS TO WARM INTO THE MID AND UPPER 90S FOR MUCH OF CENTRAL GEORGIA TODAY...LOWER 90S NORTH. THE WARM...DRY TREND WILL PERSIST THROUGH SUNDAY...THEN A RETURN FLOW SETS UP ON MONDAY WITH A WEAKNESS IN THE UPPER LEVELS...SUGGESTING A RETURN TO ISOLATED AFTERNOON CONVECTION ON MONDAY. AN INTERESTING NOTE...A WAVE CURRENTLY IN THE CENTRAL CARIBBEAN IS PROGD BY THE GFS TO STRENGTHEN AND PUSH INTO THE WESTERN GULF BY MONDAY AFTERNOON. WILL HAVE TO MONITOR THIS POTENTIAL CLOSELY OVER THE NEXT FEW DAYS. A HURRICANE HUNTER AIRCRAFT WILL FLY THE SYSTEM TODAY... AND PROVIDE VITAL ATMOSPHERIC DATA FOR LATER COMPUTER FORECAST MODEL RUNS. SO STAY TUNED. .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... A CONTINUED MOIST SOUTHERLY WIND FLOW COUPLED WITH A WEAKNESS IN THE UPPER LEVELS WILL SUPPORT ISOLATED AFTERNOON STORMS ON TUESDAY. AN APPROACHING FRONTAL BOUNDARY AND A DEEPER INFLUX OF TROPICAL MOISTURE WILL WARRANT A CHANCE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS FOR THURSDAY AND FRIDAY. CURRENTLY...THE GFS IS TAKING THE AFOREMENTIONED TROPICAL LOW INTO SOUTH TEXAS BY MID WEEK. SUGGEST ALL INTERESTS CONTINUE TO MONITOR THIS SYSTEM FOR THE NEXT SEVERAL DAYS. && .FIRE WEATHER... THE DRY SUBSIDENT AIR ON THE WEST SIDE OF TROPICAL DEPRESSION THREE WILL HELP AFTERNOON RH VALUES TO DIP INTO THE UPPER 20S AND LOWER 30S TODAY AND SUNDAY. OTHERWISE...NO CRITICAL FIRE WEATHER CONCERNS ARE ANTICIPATED OVER THE NEXT SEVERAL DAYS. && .PRELIMINARY POINT TEMPS/POPS... ATHENS 94 67 95 72 92 / 5 5 0 5 10 ATLANTA 92 72 93 73 90 / 5 5 5 5 10 BLAIRSVILLE 89 64 89 65 89 / 5 10 10 10 20 CARTERSVILLE 92 63 93 68 91 / 5 10 5 10 10 COLUMBUS 95 71 97 74 92 / 5 5 5 5 10 GAINESVILLE 91 69 94 70 90 / 5 10 5 5 20 MACON 96 68 98 72 97 / 10 5 0 5 10 ROME 94 65 95 70 93 / 5 10 10 10 10 PEACHTREE CITY 93 62 94 67 90 / 5 5 5 5 10 VIDALIA 97 74 97 70 97 / 20 10 0 5 20 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 39
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
318 AM CDT SAT JUL 19 2008 .DISCUSSION... 403 PM CDT FORECAST PROBLEM IS MAGNITUDE OF SHRA AND TS THREAT TONIGHT AND SAT...AS WELL AS POTENTIAL FOR SIGNIFICANT RAINFALL. A WEAK SURFACE BOUNDARY HAS BEEN LOCATED ACROSS FAR NORTHERN IL ALL DAY...WHILE A LAKE ENHANCED OUTFLOW HAS SETTLED INTO FAR NE IL. DEW POINTS HAVE BEEN POOLING S OF THESE BOUNDARIES WITH 20Z READINGS IN THE LOWER 70S COMMON. CAP THAT HAD BEEN IN PLACE ACROSS THE FA THE LAST COUPLE DAYS IN NOW MARGINAL OR NON EXISTENT BASED ON ACARS TEMP PROFILES ALLOWING SCT SHRA AND ISOLD TS TO DEVELOP BETWEEN 19Z AND 20Z AS SURFACE TEMPS REACHED MID 80S TO LOWER 90S. WITH MID LEVELS WARMER POSITIVE AREA NOT AS LARGE SO DO NOT EXPECT EXCESSIVELY VIGOROUS UPDRAFTS THOUGH WITH PRECIPITABLE WATER VALES APPROACHING 2 INCHES CONVECTIVE CELLS LIKELY TO BE EFFICIENT RAINFALL PRODUCERS. GFS AND NAM MODELS HAVE CAUGHT ON TO THE PRESENCE OF BOTH A COMPACT MID LEVEL LOW ON THE FAR EASTERN NE-KS BORDER...AS WELL AS AN H8 CIRCULATION IN FAR NW MO PER PROFILER AND 88D NETWORKS ALONG WITH SATELLITE DERIVED WINDS. THESE MODELS MOVE THE MID LEVEL LOW NE TO EASTERN IA BY 06Z SAT AND CONTINUE LIFTING ACROSS NW IL TO SOUTHERN WI DURING SAT MORNING. ENHANCED LOW LEVEL CONVERGENCE ACROSS NORTHERN IL AHEAD OF THE LOW LEVEL CIRCULATION AS WELL AS INCREASING UVV AS THE MID LEVEL FEATURE CONTINUES TO APPROACH FROM THE W. THIS EXPECTED TO CONTINUE DEVELOPMENT OF SHRA AND TS ACROSS NE MO AND SE IA ACROSS NORTHERN IL TONIGHT. DO NOT ANTICIPATE EXCESSIVE TRAINING OF CELLS BUT ONLY LOCALLY HEAVY DOWNPOURS SO NO FLASH FLOOD/FLOOD WATCHES ISSUED AT THIS TIME. CONTINUED CHANCES OF SHRA AND TS INTO SAT AFTERNOON AS MID LEVEL TROF SLOWLY PROGRESSES EASTWARD TO SOUTHERN LK MI BY 00Z SUN. SOME UNCERTAINTIES FOR SAT NIGHT THRU MON NIGHT WITH PROSPECTS FOR MORE RAIN. OPERATIONAL GFS FITS WELL WITH GFS ENSEMBLE MEAN IN BRINGING A SHORT WAVE ESE ACROSS THE UPPER MS VALLEY AND ACROSS SOUTHERN WI AND NORTHERN IL SAT NIGHT AND SUN MORNING WHILE NAM HAS AXIS OF QPF FAR REMOVED TO THE N ACROSS FAR NORTHERN WI AND THE U.P. OF MI. ECMWF AND UKMET ALSO SHOW THE MORE SOUTHERN TRACK SO GIVEN MAJORITY OF SOLUTIONS BRINGING RAIN ACROSS THE FA SAT NIGHT INTO SUN WILL MAINTAIN CHC POPS AS UPPER TROF DEVELOPS OVER THE GRTLKS AND LIKELY TO SEE PERIODIC IMPULSES ROTATING SE ACROSS THE UPPER MIDWEST AND INTO THE WESTERN LAKES. TRS && .AVIATION... 1250 AM CDT 0600 UTC TAFS...A SOUTHWESTERLY LOW LEVEL JET WILL CONTINUE TO ADVECT A VERY MOIST LOW LEVEL AIR MASS INTO NORTHERN ILLINOIS OVERNIGHT AND WILL ALSO SERVE AS A FOCUS FOR CONTINUED RAIN SHOWERS. AS THE LOW LEVEL JET AXIS CONTINUES TO SHIFT EASTWARD THROUGH THE OVERNIGHT HOURS...EXPECTING RAIN SHOWERS TO AFFECT ALL OF THE FORECAST TERMINALS DURING THE OVERNIGHT HOURS. WATER VAPOR IMAGERY ALSO SUGGESTING PRESENCE OF AN UPPER LEVEL SHORT WAVE MOVING THROUGH NORTHERN MISSOURI WHERE SHOWER COVERAGE HAS BEEN INCREASING OVER PAST HOUR OR SO. ALTHOUGH RADAR IMAGERY SUGGESTS MAIN RAIN BAND ACROSS NORTHERN ILLINOIS IS SLOWLY MIGRATING NORTHWARD...WOULD EXPECT FOCUS FOR THE MORE ORGANIZED RAIN SHOWER ACTIVITY TO BEGIN TO TAKE SHAPE A BIT FURTHER SOUTH POSSIBLY CLOSER TO INTERSTATE 88 CORRIDOR WHERE BEST LOW LEVEL CONVERGENCE WITH THE LOW LEVEL JET IS EXPECTED. THIS FORCING SHOULD RESULT IN SOME FAIRLY DECENT RAINS FOR ALL OF NORTHEAST ILLINOIS TERMINALS. HAVE NOT INCLUDED THUNDER MENTION AT THIS TIME DUE TO UNIMPRESSIVE MID LEVEL LAPSE RATES...BUT ISOLATED THUNDER IS A POSSIBILITY. EXPECTING PRECIP TO DIMINISH/MOVE OFF TO THE EAST BY MID MORNING AS LOW LEVEL CONVG ASSOCIATED WITH LOW LEVEL JET WEAKENS. SFC GRADIENT WILL REMAIN VERY WEAK TODAY IN THE WAKE OF THIS PRECIPITATION WITH A WEAK SFC BOUNDARY LIKELY REMAINING JUST SOUTH OF TERMINALS. WITH THE TERMINALS NORTH OF THIS BOUNDARY...EXPECTING A WEAK SOUTHEAST OR EAST FLOW TO AFFECT TERMINALS TODAY ALTHOUGH IT IS POSSIBLE MDW/GYY COULD EXPERIENCE SOUTH SOUTHWEST WINDS LATER THIS AFTERNOON. WIND SPEEDS SHOULD BE ON THE LIGHT SIDE TODAY WITH SPEEDS LESS THAN 10 KNOTS. PRECIP POTENTIAL BY THIS EVENING SHOULD BE MAXIMIZED NORTH OF THE AREA INTO WISCONSIN AS NEXT SFC WAVE DEVELOPS ALONG ANOTHER SFC BOUNDARY TO THE NORTH OF THE AREA. MARSILI && .MARINE... 316 AM CDT OLD STALLED FRONTAL BOUNDARY WILL CONTINUE TO BE MAIN FEATURE OF INTEREST IN TERMS OF LAKE MICHIGAN FORECAST TODAY WITH EAST TO NORTHEAST WINDS NORTH OF THIS BOUNDARY AND LIGHT SOUTH SOUTHEAST WINDS TO THE SOUTH OF THE BOUNDARY. ANOTHER SURFACE LOW WILL DEVELOP ACROSS SOUTHERN MINNESOTA TONIGHT AND MOVE ALONG THIS OLD BOUNDARY AND ACROSS SOUTHERN LAKE MICHIGAN BY MIDDAY SUNDAY. AS THIS LOW PRESSURE AREA MOVES OFF TO THE EAST SUNDAY...WINDS WILL BECOME NORTH NORTHWEST BEHIND THIS LOW PRESSURE AREA BY SUNDAY EVENING. SUNDAY EVENING WILL LIKELY BE THE TIME PERIOD OF STRONGEST WIND SPEEDS WITH THE NORTH WINDS GENERALLY IN THE 10 TO 15 KNOT RANGE...PERHAPS GUSTING TO 20 KNOTS ACROSS THE FAR SOUTH EARLY EVENING. OTHERWISE...WINDS WILL THEN DIMINISH AGAIN MONDAY AND TUESDAY AS A SURFACE RIDGE AXIS SLOWLY BUILDS BACK INTO THE WESTERN GREAT LAKES REGION. IN TERMS OF PRECIPITATION...AN AREA OF SHOWERS AND A FEW EMBEDDED THUNDERSTORMS WILL AFFECT FAR SOUTHERN LAKE MICHIGAN THIS MORNING...AND THEN NEXT BETTER CHANCE OF THUNDERSTORMS WILL BE LATE TONIGHT AFTER MIDNIGHT AS ANOTHER CONVECTIVE COMPLEX IS EXPECTED TO MOVE ACROSS LAKE MICHIGAN. MARSILI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1253 AM CDT SAT JUL 19 2008 .DISCUSSION... 403 PM CDT FORECAST PROBLEM IS MAGNITUDE OF SHRA AND TS THREAT TONIGHT AND SAT...AS WELL AS POTENTIAL FOR SIGNIFICANT RAINFALL. A WEAK SURFACE BOUNDARY HAS BEEN LOCATED ACROSS FAR NORTHERN IL ALL DAY...WHILE A LAKE ENHANCED OUTFLOW HAS SETTLED INTO FAR NE IL. DEW POINTS HAVE BEEN POOLING S OF THESE BOUNDARIES WITH 20Z READINGS IN THE LOWER 70S COMMON. CAP THAT HAD BEEN IN PLACE ACROSS THE FA THE LAST COUPLE DAYS IN NOW MARGINAL OR NON EXISTENT BASED ON ACARS TEMP PROFILES ALLOWING SCT SHRA AND ISOLD TS TO DEVELOP BETWEEN 19Z AND 20Z AS SURFACE TEMPS REACHED MID 80S TO LOWER 90S. WITH MID LEVELS WARMER POSITIVE AREA NOT AS LARGE SO DO NOT EXPECT EXCESSIVELY VIGOROUS UPDRAFTS THOUGH WITH PRECIPITABLE WATER VALES APPROACHING 2 INCHES CONVECTIVE CELLS LIKELY TO BE EFFICIENT RAINFALL PRODUCERS. GFS AND NAM MODELS HAVE CAUGHT ON TO THE PRESENCE OF BOTH A COMPACT MID LEVEL LOW ON THE FAR EASTERN NE-KS BORDER...AS WELL AS AN H8 CIRCULATION IN FAR NW MO PER PROFILER AND 88D NETWORKS ALONG WITH SATELLITE DERIVED WINDS. THESE MODELS MOVE THE MID LEVEL LOW NE TO EASTERN IA BY 06Z SAT AND CONTINUE LIFTING ACROSS NW IL TO SOUTHERN WI DURING SAT MORNING. ENHANCED LOW LEVEL CONVERGENCE ACROSS NORTHERN IL AHEAD OF THE LOW LEVEL CIRCULATION AS WELL AS INCREASING UVV AS THE MID LEVEL FEATURE CONTINUES TO APPROACH FROM THE W. THIS EXPECTED TO CONTINUE DEVELOPMENT OF SHRA AND TS ACROSS NE MO AND SE IA ACROSS NORTHERN IL TONIGHT. DO NOT ANTICIPATE EXCESSIVE TRAINING OF CELLS BUT ONLY LOCALLY HEAVY DOWNPOURS SO NO FLASH FLOOD/FLOOD WATCHES ISSUED AT THIS TIME. CONTINUED CHANCES OF SHRA AND TS INTO SAT AFTERNOON AS MID LEVEL TROF SLOWLY PROGRESSES EASTWARD TO SOUTHERN LK MI BY 00Z SUN. SOME UNCERTAINTIES FOR SAT NIGHT THRU MON NIGHT WITH PROSPECTS FOR MORE RAIN. OPERATIONAL GFS FITS WELL WITH GFS ENSEMBLE MEAN IN BRINGING A SHORT WAVE ESE ACROSS THE UPPER MS VALLEY AND ACROSS SOUTHERN WI AND NORTHERN IL SAT NIGHT AND SUN MORNING WHILE NAM HAS AXIS OF QPF FAR REMOVED TO THE N ACROSS FAR NORTHERN WI AND THE U.P. OF MI. ECMWF AND UKMET ALSO SHOW THE MORE SOUTHERN TRACK SO GIVEN MAJORITY OF SOLUTIONS BRINGING RAIN ACROSS THE FA SAT NIGHT INTO SUN WILL MAINTAIN CHC POPS AS UPPER TROF DEVELOPS OVER THE GRTLKS AND LIKELY TO SEE PERIODIC IMPULSES ROTATING SE ACROSS THE UPPER MIDWEST AND INTO THE WESTERN LAKES. TRS && .AVIATION... 1250 AM CDT 0600 UTC TAFS...A SOUTHWESTERLY LOW LEVEL JET WILL CONTINUE TO ADVECT A VERY MOIST LOW LEVEL AIR MASS INTO NORTHERN ILLINOIS OVERNIGHT AND WILL ALSO SERVE AS A FOCUS FOR CONTINUED RAIN SHOWERS. AS THE LOW LEVEL JET AXIS CONTINUES TO SHIFT EASTWARD THROUGH THE OVERNIGHT HOURS...EXPECTING RAIN SHOWERS TO AFFECT ALL OF THE FORECAST TERMINALS DURING THE OVERNIGHT HOURS. WATER VAPOR IMAGERY ALSO SUGGESTING PRESENCE OF AN UPPER LEVEL SHORT WAVE MOVING THROUGH NORTHERN MISSOURI WHERE SHOWER COVERAGE HAS BEEN INCREASING OVER PAST HOUR OR SO. ALTHOUGH RADAR IMAGERY SUGGESTS MAIN RAIN BAND ACROSS NORTHERN ILLINOIS IS SLOWLY MIGRATING NORTHWARD...WOULD EXPECT FOCUS FOR THE MORE ORGANIZED RAIN SHOWER ACTIVITY TO BEGIN TO TAKE SHAPE A BIT FURTHER SOUTH POSSIBLY CLOSER TO INTERSTATE 88 CORRIDOR WHERE BEST LOW LEVEL CONVERGENCE WITH THE LOW LEVEL JET IS EXPECTED. THIS FORCING SHOULD RESULT IN SOME FAIRLY DECENT RAINS FOR ALL OF NORTHEAST ILLINOIS TERMINALS. HAVE NOT INCLUDED THUNDER MENTION AT THIS TIME DUE TO UNIMPRESSIVE MID LEVEL LAPSE RATES...BUT ISOLATED THUNDER IS A POSSIBILITY. EXPECTING PRECIP TO DIMINISH/MOVE OFF TO THE EAST BY MID MORNING AS LOW LEVEL CONVG ASSOCIATED WITH LOW LEVEL JET WEAKENS. SFC GRADIENT WILL REMAIN VERY WEAK TODAY IN THE WAKE OF THIS PRECIPITATION WITH A WEAK SFC BOUNDARY LIKELY REMAINING JUST SOUTH OF TERMINALS. WITH THE TERMINALS NORTH OF THIS BOUNDARY...EXPECTING A WEAK SOUTHEAST OR EAST FLOW TO AFFECT TERMINALS TODAY ALTHOUGH IT IS POSSIBLE MDW/GYY COULD EXPERIENCE SOUTH SOUTHWEST WINDS LATER THIS AFTERNOON. WIND SPEEDS SHOULD BE ON THE LIGHT SIDE TODAY WITH SPEEDS LESS THAN 10 KNOTS. PRECIP POTENTIAL BY THIS EVENING SHOULD BE MAXIMIZED NORTH OF THE AREA INTO WISCONSIN AS NEXT SFC WAVE DEVELOPS ALONG ANOTHER SFC BOUNDARY TO THE NORTH OF THE AREA. MARSILI && .MARINE... 1245 PM CDT STILL REMAINING IN A WEAK LOW PATTERN EXTENDING FROM EAST ONTARIO BACK SW TO THE NRN PLAINS. A FRONTAL BOUNDARY EXTENDING WEST FROM THE FIRST LOW PRESSURE IN ONTARIO WILL SAG SOUTH TONIGHT...SETTING UP NORTHEAST WINDS ACROSS THE NORTHERN HALF OF LAKE MICHIGAN TONIGHT. THE FRONT SHUD STALL OVER THE SOUTHERN HALF OF LAKE MICHIGAN SATURDAY. THEN A SECOND LOW PRESSURE AREA WILL DEEPEN ALONG THIS FRONT SATURDAY NIGHT AND TRACK ACROSS SOUTHERN LAKE MICHIGAN. THIS ALLOWS THE FRONT TO DROP SOUTH OF THE LAKE ON SUNDAY. NORTHWEST WINDS ARE EXPECTED ACROSS LAKE MICHIGAN SUNDAY WITH WEAK FLOW LEAVING SPEEDS OF ONLY 10 KNOTS OR LESS. WIND DIRECTIONS FOR THE EARLY PART OF NEXT WEEK CONFLICT WITH MODEL GUIDANCE WITH REGARDS TO LOCATION AND INTENSITY OF SURFACE HIGH MOVING INTO THE WESTERN GREAT LAKES. FOR NOW HAVE CONTINUED IDEA OF MAINTAINING WEST WINDS MON AND TUE AS RIDGE SLOWLY BUILDS INTO THE WESTERN GREAT LAKES. THE WEAK SURFACE GRADIENT ACROSS THE AREA SHOULD NOT PROMOTE MUCH WAVE ACTION WITH GENERALLY 2 FEET OR LESS FROM TONIGHT THROUGH THE EARLY PART OF NEXT WEEK. RLB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
345 AM EDT SAT JUL 19 2008 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW OVER THE NRN TIER CONUS. QUIET NGT OVER THE CWA WITH SFC RDG OVER ONTARIO NOSING TOWARD THE FA AND STABLE AIRMASS WITH WELL DEFINED CAP ARND H7 AS SHOWN ON 00Z INL RAOB/TAMDAR SDNG FM SAW. CONVECTION THAT IMPACTED THE SE ZNS ALG TROF EARLIER IN THE EVNG HAVE WEAKENED/ PUSHED TO THE S WITH THAT TROF. SINCE LLVLS NEVER DRIED SGNFTLY IN THE WAKE OF THE TROF...SOME FOG HAS DVLPD. A PAIR OF SHRTWVS OF INTERNEST NOTED UPSTREAM. THE FIRST OF THESE IS PUSHING INTO THE NRN PLAINS AND CAUSING QUITE A BIT OF SHRA/TSRA IN THE DAKOTAS. HI CLDS IN ADVANCE OF THESE SHRA ARE PUSHING INTO MN. ANOTHER TRAILING SHRTWV IS MOVING EWD ALG THE CNDN BORDER JUST N OF MT. MAIN FCST CONCERNS THIS PACKAGE ARE PCPN CHCS THIS WEEKEND INTO EARLY NEXT WEEK ASSOCIATED WITH COMPLEX INTERACTION OF PAIR OF SHRTWVS UPSTREAM. FOR TDAY...SHRTWV RDG/SFC HI PRES RDG AXIS IS FCST TO BE OVHD THIS MRNG. EXPECT ANY FOG TO BURN OFF QUICKLY WITH RETURN OF DIURNAL HTG. SHRTWV NOW MOVING INTO THE NRN PLAINS IS PROGGED TO REACH NRN MN BY 00Z SUN. LATEST MODEL GUIDANCE HAS TRENDED SLOWER TO BRING DEEP MSTR EWD WITH MORE RESILIENT HI PRES/MID LVL DRY AIR. WL RESTRICT MENTION OF SCHC POPS TO AFT 21Z AND OVER ONLY WRN LK SUP WHERE 12Z ECMWF/00Z GFS SHOW SOME UPR DVGC/DEEP LYR H85-3 QVECTOR CNVGC ARRIVING IN ADVANCE OF THE SHRTWV BY 00Z. OTRW...MIXING TO H775 OR SO ON GFS/NAM FCST SDNGS YIELDS HI TEMPS IN THE MID-UPR 70S AWAY FM LK MODERATION THAT WL BE MAXIMIZED IN AREAS FAVORED BY E-NE WINDS S OF HI PRES CENTER IN ONTARIO. FOR TNGT...00Z NAM/GFS/UKMET SHOW INITIAL SHRTWV APRCHG FM THE W SPLITTING WITH SRN PIECE SUPPORTING MORE SUPPRESSED WARM FNT/SFC LO TRACKING THRU WI THAT WOULD RESULT IN INTERCEPTION OF MOST SGNFT MSTR S OF THE CWA. 00Z CNDN MODEL MORE SIMILAR TO THE 12Z ECMWF SHOWING A MORE COHESIVE SHRTWV COMING RIGHT AT THE FA WITH HIGHER QPF OVER ALL BUT THE ERN ZNS...WHICH ALL GUIDANCE EXCEPT 12Z ECMWF INDICATE WL STAY DRY. DESPITE ITS HIER QPF...EVEN THE 12Z ECMWF HINTS AT WARM FNT WELL TO THE S...WITH APRNT RELIANCE ON UPR DVGC IN RRQ OF SUBTLE H3 JET MAX IN SE CAN TO GENERATE PCPN OVER THE FA WELL N OF THIS BNDRY. OVERALL...CUT POPS A BIT ESPECIALLY OVER E...WHERE EVEN THE STRONGER CNDN MODEL IS DRY THRU 12Z SUN AND ELY FLOW OUT OF DRY HUDSON BAY HI PRES WOULD FURTHER REDUCE PCPN CHCS. SINCE EVEN THE MOISTER ECWMF SHOWS SSI GREATER THAN 0 OVER THE ENTIRE FA... REMOVED ALL MENTION OF TS. TRAILING SHRTWV NOW JUST N OF MT PROGGED TO REACH NRN MN BY 00Z MON. THE APRCH OF THIS SYS WL MAINTAIN UPR TROFFINESS...BUT GUIDANCE (INCLUDING THE 12Z ECMWF) SHOWS MORE OF AN ACYC FLOW TO THE N OF A WEAKER...MORE SUPPRESSED LO FARTHER S. THE 00Z CNDN IS THE ONLY MODEL SHOWING A DEEPER LO FARTHER N WITH A WELL DEFINED CYC NE FLOW. OPTED TO GO WITH A BLANKET 30 POP THRU THE ENTIRE DAY AND ADD A SCHC OF AFTN TS INLAND FM LK MODERATION DESPITE RATHER MODEST LAPSE RATES SHOWN BY GFS FCST SDNGS. NAM FCST DWPTS INTO THE MID 60S SEEM UNRSNBL CONSIDERING PLACEMENT OF WARM FNT TO THE S AND LACK OF ANY STRG LLVL ADVCTN WITH HUDSON BAY HI STILL LINGERING. WL MAINTAIN GOING 30 POP SUN NGT AS SHRTWV/HINT OF H5 THERMAL TROF SWINGS SE ACRS THE UPR LKS... ALBEIT IN ABSENCE OF DIURNAL HTG. HGTS BEGIN TO RISE SLOWLY ON MON ONCE SHRTWV PULLS TO THE E...BUT SLOWED DOWN DEPARTURE OF CHC POPS ON MON TO REFLECT MORE PERSISTENT MID LVL MSTR/LOWER H5 TEMPS SHOWN BY 00Z NAM/GFS/UKMET THRU THE DAY. WL MAINTAINED DRY FCST FOR MON NGT WITH DEPARTURE OF UPR TROF AND DEEP MSTR/LACK OF DIURNAL HTG. COORDINATED WITH DLH/GRB/LOT/APX. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT VFR CONDITIONS TO DETERIORATE THROUGH THE NIGHT. KCMX WILL DROP TO LIFR TONIGHT WITH LIGHT WINDS AND PLENTY OF LOW LEVEL MOISTURE AROUND TO FORM FOG AND GROUND FOG BEFORE HEATING IN THE MORNING MIXES THIS BACK OUT. AT KSAW...EXPECT LIFR CONDITIONS LATER TONIGHT WITH LOW LEVEL MOISTURE AND LIGHT WINDS AROUND CAUSING FOG/GROUND FOG. HEATING WILL MIX THIS OUT SATURDAY MORNING AND CONDITIONS WILL RETURN TO VFR. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... FOG IS STUBBORN TO DISSIPATE...BUT IS MOST RESILIENT OVR COOLER WATERS OF ERN LAKE SUPERIOR. EXPECT THE FOG TO GRADUALLY LIFT THROUGH THE DAY WITH INCREASING WINDS AND MIXING. STRONGEST WINDS THROUGH NEXT COUPLE DAYS OCCUR OVR FAR WEST LAKE SUPERIOR WITH NE WINDS FUNNELING DOWN TOWARD HEAD OF LAKE SUPERIOR AS WAVE OF LOW PRESSURE SLIDES BY JUST TO THE SOUTH. SINCE RIDGE OVR LAKE SUPERIOR IS FAIRLY WEAK LEADING TO A WEAKER PRESSURE GRADIENT...WINDS SHOULD NOT EXCEED 20 KNOTS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...KC AVIATION...DLG MARINE...JLA
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NWS LOS ANGELES/OXNARD CA
434 AM PDT SAT JUL 19 2008 ...UPDATED AVIATION SECTION... .SHORT TERM...(TODAY-MONDAY) LOW CLOUD REGIME VERY SIMILAR TO 24-HOURS AGO. LATEST ACARS SOUNDING NEAR KLAX INDICATED MARINE LAYER NEAR 1100 FT DEEP. WITH EDDY IN PLACE...EXPECT MARINE LAYER TO DEEPEN TO AT LEAST 1500 FT LATER THIS MORNING. STRATUS ALREADY ACROSS LA COUNTY VALLEYS AND PORTIONS OF THE VENTURA COUNTY VALLEYS. CURRENT LAX-DAG SFC GRAD IS ALSO SIMILAR TO YESTERDAY...HOWEVER WRF MODEL STRENGTHENS ONSHORE GRAD TO NEAR +8.9 MB THIS AFTERNOON AND A WEAK UPPER LVL LOW OFF THE SO CAL COAST WILL HELP TO REINFORCE LOW CLOUDS ACROSS THE LA/VTU/SBA COASTAL AND VALLEY AREAS. WITH A RELATIVE STRONG INVERSION IN PLACE...LOW CLOUDS SHOULD BURNOFF BY MID MORNING IN VALLEY LOCATIONS...THEN BY MID AFTERNOON ACROSS THE COASTAL PLAIN. HOWEVER...THE BEACHES COULD REMAIN MOSTLY CLOUDY MOST OF THE DAY. TEMPS SHOULD BE A DEGREE OR TWO COOLER TODAY IN MOST AREAS WITH STRONGER ONSHORE PUSH. THE WEAK CUTOFF LOW OFF THE SO CAL COAST FILLS IN QUICKLY THIS AFTERNOON AS A BROADER TROF TO THE NORTHWEST PULLS IT IN. THERE WILL CONTINUE TO BE A STRONG MARINE INFLUENCE ACROSS THE COASTAL AREAS ON SUNDAY AS THERMAL TROF STRENGTHENS ACROSS THE EASTERN CAL DESERTS. TO THE EAST...UPPER LVL HIGH BEGINS TO RE-ESTABLISH ACROSS THE 4-CORNERS REGION TODAY WHICH SHOULD OPEN THE GATEWAY FOR MID-LVL MOISTURE TO PUSH IN FROM AZ/MEXICO. GFS/WRF/ECMWF INDICATED ABUNDANT 500-700 MB MOISTURE MOVING INTO SE CAL LATE TODAY. NOT EXPECTING ANY CONVECTION ACROSS THE FORECAST AREA AS THE BULK OF MOISTURE STAYS TO THE EAST TODAY. HOWEVER ON SUNDAY...MONSOONAL FRONT (850 MB DEWPOINTS OVER 8 DEGREES C) BEGIN TO MOVE ACROSS ERN LA COUNTY. PWAT VALUES OF 1.5" WILL BE IN PLACE ACROSS LA COUNTY AS WELL. IT IS TOO EARLY TO INDICATE ANY INVERTED TROFS OR DEFORMATION ZONES MOVING AROUND THE HIGH TO HELP KICK OFF TSTMS...BUT AFTERNOON CONVECTIVE TEMPS SHOULD INITIATE SOME STORMS ACROSS THE MTNS OF LA/VTU COUNTIES AND THE ANTELOPE VALLEY. EXPECT THE SAME PATTERN ON MONDAY...WITH A BETTER CHANCE OF TSTMS ACROSS VTU/SBA COUNTY MTNS AS WELL. ONE CAVEAT...IF TOO MUCH MID LVL CLOUDINESS OCCURS...SFC HEATING COULD BE LIMITED AND TSTMS WILL HAVE A TOUGH TIME GETTING STARTED. WITH HIGH PWAT VALUES...AND WEAK STEERING WINDS AT 500MB...THERE COULD BE A THREAT OF FLASH FLOODING ACROSS PORTIONS OF THE MTNS AND ANTELOPE VALLEY SUN AND MON. LATER SHIFTS WILL MONITOR AS NEW MODEL RUNS COME IN. .LONG TERM...(TUE-FRI) BOTH THE GFS AND ECMWF ARE IN AGREEMENT AS UPPER LVL TROF MOVES EAST WHILE THE UPPER HIGH ACROSS THE 4-CORNERS REGION PERSISTS FOR THE MOST PART. TEMPS SHOULD BE SLIGHTLY COOLER ACROSS THE NRN PART OF THE FORECAST AREA DUE TO TROF PASSING TO THE NORTH. BY WED...IT IS DIFFICULT TO SAY HOW THE FLOW AROUND THE HIGH WILL AFFECT THE FORECAST AREA AS THE MODELS BEGIN TO GET OUT OF PHASE A BIT. BOTH MODELS DO ELONGATE THE HIGH TO PUSH FARTHER WEST OVER THE ERN PAC. THIS COULD POTENTIALLY SHUT DOWN THE MONSOONAL FLOW FOR A SHORT TIME BUT AS WE SAW LAST WEEK...SOME RESIDUAL MOISTURE AND SUNNY SKIES COULD POP UP A FEW TSTMS WED-FRI. EXPECT INLAND TEMPS TO REMAIN NEAR NORMAL WITH A FEW DEGREES OF WARMING BY THU-FRI AS THICKNESS LVLS RISE A BIT. TEMPS SHOULD REMAIN RELATIVELY NORMAL ACROSS THE COASTAL AREAS AS WELL DUE TO CONTINUED MARINE INFLUENCE ACROSS THE COASTAL SECTIONS. LOW CLOUDS FROM THE MARINE LAYER COULD BE DISRUPTED THROUGH THE PERIOD DUE TO MID LEVEL MOISTURE MOVING WESTWARD. && .AVIATION...19/1134Z. IFR TO MVFR CONDITIONS HAVE DEVELOPED AT MOST COASTAL AND INLAND TERMINALS...WHILE VFR CONDITIONS PERSIST AT DESERT TERMINALS. LOW CONFIDENCE EXISTS IN TIMING OF CLEARING FOR THIS AFTERNOON...ESPECIALLY FOR COASTAL TERMINALS SOUTH OF POINT CONCEPTION. A GENERAL EARLIER RETURN OF THE MARINE LAYER IS EXPECTED TONIGHT...WITH IFR TO MVFR CONDITIONS RETURNING TO SOME COASTAL TERMINALS AROUND 04Z...OR AFTER 06Z AT KOXR AND KSBA. VFR CONDITIONS ARE EXPECTED TO PERSIST AT KPRB...KPMD...AND KWJF. KLAX...MVFR CONDITIONS WILL CONTINUE TO OCCUR AT LEAST THROUGH 15Z...BUT LOW CONFIDENCE EXISTS WITH TIMING OF VFR CONDITIONS REDEVELOPING. THERE IS A 40 PERCENT CHANCE THAT VFR CONDITIONS MAY NOT DEVELOP UNTIL BETWEEN 15Z AND 19Z...WITH A 10 PERCENT CHANCE THAT VFR CONDITIONS MAY NOT DEVELOP UNTIL AFTER 21Z. MVFR CONDITIONS SHOULD RETURN AROUND 05Z TONIGHT...BUT MVFR CONDITIONS COULD DEVELOP AS SOON AS 03Z...OR AS LATE AS 06Z. SOME CONCERN EXISTS THAT INCREASING MOISTURE AT THE MIDDLE LEVELS MAY MAKE FOR A DIFFICULT MARINE LAYER FORECAST FOR TONIGHT. KBUR...IFR TO MVFR CONDITIONS WILL PERSIST THROUGH AT LEAST 15Z...WITH VFR CONDITIONS LIKELY DEVELOPING AFTER 15Z...OR 17Z AT THE LATEST. MVFR CONDITIONS WILL LIKELY RETURN TONIGHT AROUND 08Z...OR POSSIBLY AS LATE AS 10Z. HOWEVER...INCREASING MID-LEVEL MOISTURE MAY PRESENT A CHALLENGE FOR IFR TO MVFR CONDITIONS REDEVELOPING OVER KBUR. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXCWFLOX). HIGH RIP CURRENT RISK (SEE LAXSRFLOX). && $$ PUBLIC...KAPLAN AVIATION...HALL WWW.WEATHER.GOV/LOSANGELES
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
330 AM PDT SAT JUL 19 2008 .SHORT TERM...(TODAY-MONDAY) LOW CLOUD REGIME VERY SIMILAR TO 24-HOURS AGO. LATEST ACARS SOUNDING NEAR KLAX INDICATED MARINE LAYER NEAR 1100 FT DEEP. WITH EDDY IN PLACE...EXPECT MARINE LAYER TO DEEPEN TO AT LEAST 1500 FT LATER THIS MORNING. STRATUS ALREADY ACROSS LA COUNTY VALLEYS AND PORTIONS OF THE VENTURA COUNTY VALLEYS. CURRENT LAX-DAG SFC GRAD IS ALSO SIMILAR TO YESTERDAY...HOWEVER WRF MODEL STRENGTHENS ONSHORE GRAD TO NEAR +8.9 MB THIS AFTERNOON AND A WEAK UPPER LVL LOW OFF THE SO CAL COAST WILL HELP TO REINFORCE LOW CLOUDS ACROSS THE LA/VTU/SBA COASTAL AND VALLEY AREAS. WITH A RELATIVE STRONG INVERSION IN PLACE...LOW CLOUDS SHOULD BURNOFF BY MID MORNING IN VALLEY LOCATIONS...THEN BY MID AFTERNOON ACROSS THE COASTAL PLAIN. HOWEVER...THE BEACHES COULD REMAIN MOSTLY CLOUDY MOST OF THE DAY. TEMPS SHOULD BE A DEGREE OR TWO COOLER TODAY IN MOST AREAS WITH STRONGER ONSHORE PUSH. THE WEAK CUTOFF LOW OFF THE SO CAL COAST FILLS IN QUICKLY THIS AFTERNOON AS A BROADER TROF TO THE NORTHWEST PULLS IT IN. THERE WILL CONTINUE TO BE A STRONG MARINE INFLUENCE ACROSS THE COASTAL AREAS ON SUNDAY AS THERMAL TROF STRENGTHENS ACROSS THE EASTERN CAL DESERTS. TO THE EAST...UPPER LVL HIGH BEGINS TO RE-ESTABLISH ACROSS THE 4-CORNERS REGION TODAY WHICH SHOULD OPEN THE GATEWAY FOR MID-LVL MOISTURE TO PUSH IN FROM AZ/MEXICO. GFS/WRF/ECMWF INDICATED ABUNDANT 500-700 MB MOISTURE MOVING INTO SE CAL LATE TODAY. NOT EXPECTING ANY CONVECTION ACROSS THE FORECAST AREA AS THE BULK OF MOISTURE STAYS TO THE EAST TODAY. HOWEVER ON SUNDAY...MONSOONAL FRONT (850 MB DEWPOINTS OVER 8 DEGREES C) BEGIN TO MOVE ACROSS ERN LA COUNTY. PWAT VALUES OF 1.5" WILL BE IN PLACE ACROSS LA COUNTY AS WELL. IT IS TOO EARLY TO INDICATE ANY INVERTED TROFS OR DEFORMATION ZONES MOVING AROUND THE HIGH TO HELP KICK OFF TSTMS...BUT AFTERNOON CONVECTIVE TEMPS SHOULD INITIATE SOME STORMS ACROSS THE MTNS OF LA/VTU COUNTIES AND THE ANTELOPE VALLEY. EXPECT THE SAME PATTERN ON MONDAY...WITH A BETTER CHANCE OF TSTMS ACROSS VTU/SBA COUNTY MTNS AS WELL. ONE CAVEAT...IF TOO MUCH MID LVL CLOUDINESS OCCURS...SFC HEATING COULD BE LIMITED AND TSTMS WILL HAVE A TOUGH TIME GETTING STARTED. WITH HIGH PWAT VALUES...AND WEAK STEERING WINDS AT 500MB...THERE COULD BE A THREAT OF FLASH FLOODING ACROSS PORTIONS OF THE MTNS AND ANTELOPE VALLEY SUN AND MON. LATER SHIFTS WILL MONITOR AS NEW MODEL RUNS COME IN. .LONG TERM...(TUE-FRI) BOTH THE GFS AND ECMWF ARE IN AGREEMENT AS UPPER LVL TROF MOVES EAST WHILE THE UPPER HIGH ACROSS THE 4-CORNERS REGION PERSISTS FOR THE MOST PART. TEMPS SHOULD BE SLIGHTLY COOLER ACROSS THE NRN PART OF THE FORECAST AREA DUE TO TROF PASSING TO THE NORTH. BY WED...IT IS DIFFICULT TO SAY HOW THE FLOW AROUND THE HIGH WILL AFFECT THE FORECAST AREA AS THE MODELS BEGIN TO GET OUT OF PHASE A BIT. BOTH MODELS DO ELONGATE THE HIGH TO PUSH FARTHER WEST OVER THE ERN PAC. THIS COULD POTENTIALLY SHUT DOWN THE MONSOONAL FLOW FOR A SHORT TIME BUT AS WE SAW LAST WEEK...SOME RESIDUAL MOISTURE AND SUNNY SKIES COULD POP UP A FEW TSTMS WED-FRI. EXPECT INLAND TEMPS TO REMAIN NEAR NORMAL WITH A FEW DEGREES OF WARMING BY THU-FRI AS THICKNESS LVLS RISE A BIT. TEMPS SHOULD REMAIN RELATIVELY NORMAL ACROSS THE COASTAL AREAS AS WELL DUE TO CONTINUED MARINE INFLUENCE ACROSS THE COASTAL SECTIONS. LOW CLOUDS FROM THE MARINE LAYER COULD BE DISRUPTED THROUGH THE PERIOD DUE TO MID LEVEL MOISTURE MOVING WESTWARD. && .AVIATION...DISCUSSION FOLLOWING 12Z TAF PACKAGE. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXCWFLOX). HIGH RIP CURRENT RISK (SEE LAXSRFLOX). && $$ PUBLIC...KAPLAN AVIATION...HALL WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
946 AM EDT SAT JUL 19 2008 .SYNOPSIS... HIGH PRESSURE WILL SLOWLY MOVE OFF THE COAST TODAY WHILE A COLD FRONT APPROACHES THE REGION SUNDAY BEFORE PASSING THROUGH MONDAY. THIS FRONT WILL STALL OUT CLOSE TO THE AREA FOR THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WATER VAPOR LOOP SHOWS A RIDGE FROM THE SOUTHWEST CONUS EAST INTO THE MID ATLANTIC. A SYSTEM WAS OFF THE GEORGIA COAST...WITH THE MEAN FLOW RESIDING ALONG THE CANADIAN BORDER. ACARS 400-250MB WIND OBSERVATIONS SHOW A 80-110KT JET FROM THE PACIFIC NORTHWEST EAST NORTHEAST OVER THE UPPER GREAT LAKES AND NEW ENGLAND. LIGHT WINDS RESIDED OVER THE SOUTHEAST CONUS. 11Z SURFACE ANALYSIS PLACED A 1010MB CYCLONE OFF THE GEORGIA COAST. 1019MB ANTICYCLONE DOMINATED THE CENTRAL APPALACHIANS...WELL AHEAD OF THE COLD FRONT STALLED ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION. A TROUGH WAS NOTED IN THE LEE OF THE CENTRAL APPALACHIANS. REGION REMAINS IN A SUBSISTENT ZONE NORTH OF TROPICAL DEPRESSION 3...AND SOUTH OF THE MEAN WESTERLIES. MID DECK STREAMING IN FROM THE SOUTHWEST BEING SHEARED NORTHWARD BY A COL NORTHWEST OF THE AFOREMENTIONED SYSTEM. WHILE CLOUD DECK MAY TEND TO THIN AS IT PROGRESSES NORTHEAST THIS AFTERNOON...HAVE LOWERED TEMPERATURES ACROSS THE SOUTH CENTRAL AND SOUTHWEST ZONES AS A RESULT. OTHERWISE...EXPECT CUMULUS GROWTH ACROSS THE EASTERN ZONES WHERE MOISTURE HAS RETURNED AHEAD OF THE SYSTEM. COMBINATION OF WARM SUMMER TEMPERATURES AND RETURN OF MOISTURE FROM THE SOUTHEAST SHOULD YIELD HEAT INDEX VALUES NEAR 100F THIS AFTERNOON ALONG AND EAST OF INTERSTATE 95. IT WILL BE MOST NOTABLE IN URBAN AREAS AND ALONG THE BAY. WILL ISSUE A SPECIAL WEATHER STATEMENT LATER THIS MORNING PERTAINING TO HEAT INDEX VALUES. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/... SURFACE HIGH PRESSURE WILL BEGIN TO BREAK DOWN OVERNIGHT. THE FRONT TO THE NORTH WILL SLOWLY MOVE SOUTH...WHILE THE TROPICAL SYSTEM WILL HUG THE COAST OF THE CAROLINAS. UPPER LEVEL CLOUDS WILL BEGIN TO INCREASE TONIGHT OVER THE SOUTHERN PORTIONS OF THE CWFA IN ASSOCIATION WITH THE TROPICAL SYSTEM. && .LONG TERM /SUNDAY THROUGH FRIDAY/... HIGH PRESSURE WILL REMAIN WELL OFF THE MID-ATLANTIC COAST SUNDAY WHILE THE NEXT DISTURBANCE AND ITS ASSOCIATED COOL FRONT MOVE INTO THE GREAT LAKES. A TROPICAL LOW (WHAT IS CURRENTLY TROPICAL DEPRESSION NUMBER 3) WILL REMAIN VERY CLOSE TO THE NORTH CAROLINA COAST. THIS SYSTEM HAS THE POTENTIAL TO BECOME A TROPICAL STORM BETWEEN NOW AND SUNDAY...AND IF IT DOES IT WOULD BE NAMED CRISTOBAL. OUR REGION SHOULD REMAIN IN A SUBSIDENCE REGION BETWEEN THE TROPICAL SYSTEM AND THE COOL FRONT APPROACHING FROM THE GREAT LAKES. THEREFORE...WILL LEAVE FORECAST DRY FOR NOW WITH MAX TEMPERATURES ABOVE CLIMO. COULD SEE A STRAY SHOWER/T-STORM POP UP ACROSS A FEW LOCATIONS DURING THE AFTERNOON...BUT IT DOES APPEAR THAT MOST PLACES WILL BE DRY. THE TROPICAL LOW SHOULD PASS BY WELL TO OUR EAST WITH NO EFFECTS ON OUR REGION MONDAY. HOWEVER...THE COOL FRONT TO OUR NORTHWEST WILL MOVE THROUGH THE REGION BRINGING A CHANCE FOR SHOWERS AND THUNDERSTORMS. LATEST GUIDANCE DOES SHOW THE FRONT MOVING THROUGH A BIT FASTER...PERHAPS SUGGESTING THAT THE BEST CHANCE FOR ANY SHOWER/T-STORM ACTIVITY WILL BE EAST OF THE BLUE RIDGE DURING THE AFTERNOON/EVENING HOURS. HAVE BUMPED UP MAX TEMPS A BIT...NOT MUCH COOLING EXPECTED BEHIND THE FRONT IF ANY. WESTERLY DOWNSLOPING FLOW WILL BRING ANOTHER AFTERNOON OF ABOVE CLIMO TEMPS. THE COOL FRONT WILL STALL OUT JUST TO OUR SOUTH TUESDAY AND WAVES OF LOW PRESSURE RIDING ALONG THE FRONT WILL BRING THE CHANCE FOR SHOWERS AND THUNDERSTORMS. TIMING OF THESE WAVES REMAINS UNCERTAIN...SO WILL KEEP POPS CONFINED TO THE AFTERNOON/EVENING HOURS FOR NOW. WEDNESDAY THROUGH FRIDAY REMAINS UNCERTAIN AT THIS TIME...DEPENDING ON EXACTLY WHERE THE FRONT IS. SOME GUIDANCE SUGGEST IT STAYS JUST TO OUR SOUTH KEEPING US DRY WHILE OTHER GUIDANCE RETURN IT NORTH OVER OUR CWA AS A WARM FRONT. LATEST GFS AND GEFS HAS TRENDED FURTHER NORTH WITH THE FRONT KEEPING IT OVER OUR CWA. WILL ADD CHANCE POPS ACROSS THE SOUTHERN PORTION OF OUR CWA FOR NOW GIVEN THE RECENT TREND IN 00Z LONG RANGE GUIDANCE. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... LIGHT SOUTHERLY FLOW UNDER A COMBINATION OF CUMULUS AND MID CLOUDS THIS AFTERNOON. PATCHY BR MAY BRING BRIEF PERIODS OF SUBVFR VSBYS EARLY SUNDAY MORNING...OTHERWISE VFR CONDITIONS ARE EXPECTED. A COOL FRONT WILL BRING A CHANCE FOR SHOWERS/T-STORMS MONDAY AND TUESDAY...MAINLY DURING THE AFTERNOON AND EVENING HOURS. OTHERWISE...VFR CONDITIONS ARE EXPECTED. THE FRONT SHOULD STALL OUT FAR ENOUGH TO THE SOUTH WEDNESDAY FOR VFR CONDITIONS OVER MOST OF THE TERMINALS. && .MARINE... HAVE ISSUED A SMALL CRAFT ADVISORY FOR THE MID BAY AND LOWER TIDAL POTOMAC RIVER. EXPECT SOUTHERLY CHANNELING TO DEVELOP LATE THIS AFTERNOON AND EVENING...WITH GUSTS AROUND 20 KNOTS. NO FLAGS EXPECTED DURING THE PERIOD. A COOL FRONT WILL BRING THE CHANCE FOR SHOWERS/T-STORMS MONDAY AND TUESDAY...MAINLY DURING THE AFTERNOON AND EVENING HOURS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 11 PM EDT THIS EVENING FOR ANZ532>534-537. && $$ SYNOPSIS...LASORSA NEAR TERM...ROGOWSKI SHORT TERM...LISTEMAA LONG TERM...LASORSA AVIATION...ROGOWSKI/LASORSA MARINE...ROGOWSKI/LASORSA
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1158 AM EDT SAT JUL 19 2008 .UPDATE... FOG OFF LAKE SUPERIOR CONTINUES TO BE AN ISSUE...THOUGH IT APPEARS DAYTIME HEATING IS DOING ITS JOB IN BRINGING VISIBILITIES UP ON LAND AREAS...EVEN ON THE KEWEENAW WITH UPSLOPING WINDS AT CMX. 15Z TAMDAR SOUNDING FROM SAW INDICATES TOO WHY THE FOG IS DISSIPATING WITH DRY AIR ABOVE 900MB STARTING TO MIX DOWN. THEREFORE DENSE FOG ADVISORIES HAVE BEEN CANCELLED OVER LAND. WEBCAMS STILL INDICATE THE FOG ON LAKE SUPERIOR IS DENSE...AND COVERS MUCH OF THE U.S. WATERS OF LAKE SUPERIOR. HAVE EXPANDED THE DENSE FOG ADVISORY INTO FAR WESTERN LAKE SUPERIOR WITH A SHIP REPORT NEAR DEVILS ISLAND INDICATING VSBYS LESS THAN 1/4SM. FOG MAY BE ABLE TO DISSIPATE SOME THIS AFTERNOON AS DOWNSLOPING DRIER AIR COMES OFF NE ONTARIO...AS INDICATED BY NAM 950MB RH FIELDS WHICH CONTINUE TO HAVE THE BEST REPRESENTATION OF THE FOG. OTHER ISSUE THIS AFTERNOON IS POSSIBLE LAKE BREEZE CONVERGENCE CONVECTION DEVELOPING OVER THE SOUTHERN U.P.. OUR LOCAL WRF-ARW RUN WITH THE KF SCHEME AND THE RUC DEVELOP SOME ISOLATED STORMS LATE THIS AFTN. HOWEVER...SOUNDINGS SEEM A LITTLE SUSPICIOUS... PARTICULARLY WITH THE AVAILABLE LOW LEVEL MOISTURE. MODIFYING THE 15Z TAMDAR SOUNDING FROM SAW AND A 12Z NAM SOUNDING SUGGESTS SOME CAP AS DEWPOINTS MIX DOWN INTO THE MID/UPPER 50S. THEREFORE HAVE NOT INCLUDED ANY POPS AT THIS TIME. WILL BE MONITORING FOG THIS AFTERNOON. IF IT DOES NOT DISSIPATE AS MUCH AS THE NAM IS SUGGESTING...WE MAY NEED DENSE FOG ADVISORIES AGAIN FOR AT LEAST THE KEWEENAW ONCE DIURNAL COOLING SETS IN. WILL ALSO HAVE TO WATCH FOG ON CENTRAL LAKE MICHIGAN AS A WEBCAM IN ALGOMA WI SHOWS DENSE FOG THERE...AND WITH ESE WINDS DEVELOPING IN THE LOW LEVELS TONIGHT...THIS COULD GET ADVECTED TOWARDS SE UPPER MI. PREVIOUS UPDATE ISSUED AT 911 AM EDT... ADDED EASTERN ALGER...SCHOOLCRAFT AND LUCE COUNTIES TO THE DENSE FOG ADVISORY PER ERY AND ISQ OBS...IN ADDITION TO LATEST WEBCAM AT SENEY. HOWEVER...FOG THERE SHOULD NOT LAST AS LONG AS DOWNSLOPING NE WIND ASSISTS WITH THE SUN TO HELP MIX IT OUT. IN ADDITION...ADDED A FEW EXTRA MARINE AREAS TO THE DENSE FOG ADVISORY WITH A REPORT OF 1/4SM AT TWO HEART AND WEBCAM OFF EAGLE HARBOR SHOWING FOG JUST OFFSHORE. ANOTHER DENSE FOG ADVISORY MAY BE NEEDED FOR FAR WESTERN LAKE SUPERIOR GIVEN VISIBLE SATELLITE TRENDS. WILL INCREASE FOG COVERAGE THERE FOR NOW. PREVIOUS UPDATE ISSUED AT 815 AM EDT... DENSE FOG THAT DEVELOPED OVER THE COLD WATERS OF LAKE SUPERIOR LAST NIGHT IS BEING ADVECTED SOUTH IN A HURRY AS WEAK HIGH PRES CENTER NORTH OF LAKE SUPERIOR DROPS SOUTH. NOT MUCH TO GO ON FM OBSERVATION STANDPOINT...BUT LAST VIS/FOG IMAGERY OF NIGHT SHOWED THE STRATUS/FOG SHIFTING SOUTH AND WEB CAMS FM EAGLE RIVER...COPPER HARBOR...AND AT CENTRAL IN HIGHER TERRAIN OF KEWEENAW COUNTY ALL SHOWED NEAR ZERO VSBY WITHIN LAST HR. FOLLOWED LOW LEVEL RH PROGS FM NAM AS IT HAD A GOOD HANDLE. INDICATIONS ARE THAT THE FOG WILL AFFECT KEWEENAW ALL DAY...ONLY BOLSTERED BY AN INCREASINGLY FAVORABLE EASTERLY UPSLOPE WIND. WENT WITH DENSE FOG ADVY ALL DAY THERE AND ALSO OVR ALL OF CNTRL LK SUPERIOR AND ADJACENT NSH ZONES FM TIP OF KEWEENAW TO GRAND MARAIS. ELSEWHERE...ALONG LAKE SUPERIOR EAST OF KEWEENAW TO NORTHERN LUCE COUNTY...EXPECT FOG TO BE DENSE THIS MORNING BUT THEN TO TRY TO MIX OUT THIS AFTN WITH LOW LEVEL MIXING OVR LAND. THUS...DID NOT GO WITH DENSE FOG ADVY AWAY FM THE KEWEENAW. ONCE WE GET A HANDLE ON HOW THE FOG IS UNFOLDING THIS MORNING...FURTHER DENSE FOG ADVYS MAY BE NEEDED. MADE APPROPRIATE ADJUSTMENTS TO SKY/WX AND LOWERED TEMPS SOME MORE ALONG THE SHORE WITH PERSISTENT ONSHORE FLOW. && .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW OVER THE NRN TIER CONUS. QUIET NGT OVER THE CWA WITH SFC RDG OVER ONTARIO NOSING TOWARD THE FA AND STABLE AIRMASS WITH WELL DEFINED CAP ARND H7 AS SHOWN ON 00Z INL RAOB/TAMDAR SDNG FM SAW. CONVECTION THAT IMPACTED THE SE ZNS ALG TROF EARLIER IN THE EVNG HAVE WEAKENED/ PUSHED TO THE S WITH THAT TROF. SINCE LLVLS NEVER DRIED SGNFTLY IN THE WAKE OF THE TROF...SOME FOG HAS DVLPD. A PAIR OF SHRTWVS OF INTERNEST NOTED UPSTREAM. THE FIRST OF THESE IS PUSHING INTO THE NRN PLAINS AND CAUSING QUITE A BIT OF SHRA/TSRA IN THE DAKOTAS. HI CLDS IN ADVANCE OF THESE SHRA ARE PUSHING INTO MN. ANOTHER TRAILING SHRTWV IS MOVING EWD ALG THE CNDN BORDER JUST N OF MT. MAIN FCST CONCERNS THIS PACKAGE ARE PCPN CHCS THIS WEEKEND INTO EARLY NEXT WEEK ASSOCIATED WITH COMPLEX INTERACTION OF PAIR OF SHRTWVS UPSTREAM. FOR TDAY...SHRTWV RDG/SFC HI PRES RDG AXIS IS FCST TO BE OVHD THIS MRNG. EXPECT ANY FOG TO BURN OFF QUICKLY WITH RETURN OF DIURNAL HTG. SHRTWV NOW MOVING INTO THE NRN PLAINS IS PROGGED TO REACH NRN MN BY 00Z SUN. LATEST MODEL GUIDANCE HAS TRENDED SLOWER TO BRING DEEP MSTR EWD WITH MORE RESILIENT HI PRES/MID LVL DRY AIR. WL RESTRICT MENTION OF SCHC POPS TO AFT 21Z AND OVER ONLY WRN LK SUP WHERE 12Z ECMWF/00Z GFS SHOW SOME UPR DVGC/DEEP LYR H85-3 QVECTOR CNVGC ARRIVING IN ADVANCE OF THE SHRTWV BY 00Z. OTRW...MIXING TO H775 OR SO ON GFS/NAM FCST SDNGS YIELDS HI TEMPS IN THE MID-UPR 70S AWAY FM LK MODERATION THAT WL BE MAXIMIZED IN AREAS FAVORED BY E-NE WINDS S OF HI PRES CENTER IN ONTARIO. FOR TNGT...00Z NAM/GFS/UKMET SHOW INITIAL SHRTWV APRCHG FM THE W SPLITTING WITH SRN PIECE SUPPORTING MORE SUPPRESSED WARM FNT/SFC LO TRACKING THRU WI THAT WOULD RESULT IN INTERCEPTION OF MOST SGNFT MSTR S OF THE CWA. 00Z CNDN MODEL MORE SIMILAR TO THE 12Z ECMWF SHOWING A MORE COHESIVE SHRTWV COMING RIGHT AT THE FA WITH HIGHER QPF OVER ALL BUT THE ERN ZNS...WHICH ALL GUIDANCE EXCEPT 12Z ECMWF INDICATE WL STAY DRY. DESPITE ITS HIER QPF...EVEN THE 12Z ECMWF HINTS AT WARM FNT WELL TO THE S...WITH APRNT RELIANCE ON UPR DVGC IN RRQ OF SUBTLE H3 JET MAX IN SE CAN TO GENERATE PCPN OVER THE FA WELL N OF THIS BNDRY. OVERALL...CUT POPS A BIT ESPECIALLY OVER E...WHERE EVEN THE STRONGER CNDN MODEL IS DRY THRU 12Z SUN AND ELY FLOW OUT OF DRY HUDSON BAY HI PRES WOULD FURTHER REDUCE PCPN CHCS. SINCE EVEN THE MOISTER ECWMF SHOWS SSI GREATER THAN 0 OVER THE ENTIRE FA... REMOVED ALL MENTION OF TS. TRAILING SHRTWV NOW JUST N OF MT PROGGED TO REACH NRN MN BY 00Z MON. THE APRCH OF THIS SYS WL MAINTAIN UPR TROFFINESS...BUT GUIDANCE (INCLUDING THE 12Z ECMWF) SHOWS MORE OF AN ACYC FLOW TO THE N OF A WEAKER...MORE SUPPRESSED LO FARTHER S. THE 00Z CNDN IS THE ONLY MODEL SHOWING A DEEPER LO FARTHER N WITH A WELL DEFINED CYC NE FLOW. OPTED TO GO WITH A BLANKET 30 POP THRU THE ENTIRE DAY AND ADD A SCHC OF AFTN TS INLAND FM LK MODERATION DESPITE RATHER MODEST LAPSE RATES SHOWN BY GFS FCST SDNGS. NAM FCST DWPTS INTO THE MID 60S SEEM UNRSNBL CONSIDERING PLACEMENT OF WARM FNT TO THE S AND LACK OF ANY STRG LLVL ADVCTN WITH HUDSON BAY HI STILL LINGERING. WL MAINTAIN GOING 30 POP SUN NGT AS SHRTWV/HINT OF H5 THERMAL TROF SWINGS SE ACRS THE UPR LKS... ALBEIT IN ABSENCE OF DIURNAL HTG. HGTS BEGIN TO RISE SLOWLY ON MON ONCE SHRTWV PULLS TO THE E...BUT SLOWED DOWN DEPARTURE OF CHC POPS ON MON TO REFLECT MORE PERSISTENT MID LVL MSTR/LOWER H5 TEMPS SHOWN BY 00Z NAM/GFS/UKMET THRU THE DAY. WL MAINTAINED DRY FCST FOR MON NGT WITH DEPARTURE OF UPR TROF AND DEEP MSTR/LACK OF DIURNAL HTG. COORDINATED WITH DLH/GRB/LOT/APX. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... 15Z UPDATE...AMENDED TAFS TO REMOVE ANY VSBY RESTRICTIONS AS DAYTIME HEATING HAS ALLOWED TEMPS TO WARM ENOUGH TO REMOVE FOG. ALSO WENT MORE OPTIMISTIC WITH CIGS AT SAW AS THE LOW CLOUD OFF LAKE SUPERIOR THAT ADVECTED IN HAS MIXED OUT. A BRIEF PERIOD OF MVFR CONDITIONS COULD OCCUR THERE EARLY THIS AFTN AS DIURNAL CUMULUS DEVELOP...BUT FURTHER HEATING WILL LIKELY BRING THE CIG THEN UP TO VFR BY 20Z. AT CMX...UPSLOPE EAST FLOW SHOULD KEEP THE CIGS LOW...BUT GRADUAL IMPROVEMENT IS EXPECTED WITH CONTINUED HEATING. WILL NEED TO WATCH THE FOG ON EASTERN LAKE SUPERIOR THIS AFTN BECAUSE IF IT DOES DISSIPATE MUCH...FOG COULD RETURN AT CMX ONCE DIURNAL COOLING SETS IN. 12Z ROUTINE ISSUANCE...NOT MUCH RADIATION FOG OVERNIGHT...BUT DENSE FOG THAT FORMED OVR LAKE SUPERIOR IS PUSHING SOUTH AND WILL AFFECT BOTH TAF SITES IN SOME SHAPE THROUGH THE MORNING. BEST CHANCE OF VSBY BLO 1/2SM IS AT KCMX WITH DEVELOPING EAST ONSHORE WIND AND WITH THE KEWEENAW CLOSEST TO THE ADDED MOISTURE OFF LAKE SUPERIOR. HAVE KEPT VLIFR CONDITIONS AT KCMX ALL DAY. MEANWHILE...AT KSAW...EXPECT PRESENT CLEAR SKIES TO RAPIDLY TRANSITION TO AT LEAST IFR BY MID MORNING. DAYTIME MIXING SHOULD TRY TO MIX OUT THE LOW CLOUDS AND MOST LIKELY ANY LWR VSBY BY MID AFTN. LOW CLOUDS MAY HANG AROUND AT CMX INTO THE EVENING...BUT EVENTUALLY EXPECT CLOUDS TO LIFT TO MVFR RANGE TONIGHT. HAVE KEPT ANY PCPN OUT OF FCST TONIGHT AS UNCERTAINTY IS HIGH AS TO WHEATHER ANY PCPN WILL IMPACT TAFS AT ALL. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... FOG IS STUBBORN TO DISSIPATE...BUT IS MOST RESILIENT OVR COOLER WATERS OF ERN LAKE SUPERIOR. EXPECT THE FOG TO GRADUALLY LIFT THROUGH THE DAY WITH INCREASING WINDS AND MIXING. STRONGEST WINDS THROUGH NEXT COUPLE DAYS OCCUR OVR FAR WEST LAKE SUPERIOR WITH NE WINDS FUNNELING DOWN TOWARD HEAD OF LAKE SUPERIOR AS WAVE OF LOW PRESSURE SLIDES BY JUST TO THE SOUTH. SINCE RIDGE OVR LAKE SUPERIOR IS FAIRLY WEAK LEADING TO A WEAKER PRESSURE GRADIENT...WINDS SHOULD NOT EXCEED 20 KNOTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... DENSE FOG ADVISORY UNTIL 6 PM EDT /5 PM CDT/ THIS AFTERNOON FOR LSZ162-243>251-263>267. LAKE MICHIGAN...NONE. && $$ UPDATE...JLA/AJ DISCUSSION...KC AVIATION...JLA/AJ MARINE...JLA
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
911 AM EDT SAT JUL 19 2008 .UPDATE... ...DENSE FOG MOVING IN OFF LAKE SUPERIOR... ADDED EASTERN ALGER...SCHOOLCRAFT AND LUCE COUNTIES TO THE DENSE FOG ADVISORY PER ERY AND ISQ OBS...IN ADDITION TO LATEST WEBCAM AT SENEY. HOWEVER...FOG THERE SHOULD NOT LAST AS LONG AS DOWNSLOPING NE WIND ASSISTS WITH THE SUN TO HELP MIX IT OUT. IN ADDITION...ADDED A FEW EXTRA MARINE AREAS TO THE DENSE FOG ADVISORY WITH A REPORT OF 1/4SM AT TWO HEART AND WEBCAM OFF EAGLE HARBOR SHOWING FOG JUST OFFSHORE. ANOTHER DENSE FOG ADVISORY MAY BE NEEDED FOR FAR WESTERN LAKE SUPERIOR GIVEN VISIBLE SATELLITE TRENDS. WILL INCREASE FOG COVERAGE THERE FOR NOW. PREVIOUS UPDATE ISSUED AT 815 AM EDT... DENSE FOG THAT DEVELOPED OVER THE COLD WATERS OF LAKE SUPERIOR LAST NIGHT IS BEING ADVECTED SOUTH IN A HURRY AS WEAK HIGH PRES CENTER NORTH OF LAKE SUPERIOR DROPS SOUTH. NOT MUCH TO GO ON FM OBSERVATION STANDPOINT...BUT LAST VIS/FOG IMAGERY OF NIGHT SHOWED THE STRATUS/FOG SHIFTING SOUTH AND WEB CAMS FM EAGLE RIVER...COPPER HARBOR...AND AT CENTRAL IN HIGHER TERRAIN OF KEWEENAW COUNTY ALL SHOWED NEAR ZERO VSBY WITHIN LAST HR. FOLLOWED LOW LEVEL RH PROGS FM NAM AS IT HAD A GOOD HANDLE. INDICATIONS ARE THAT THE FOG WILL AFFECT KEWEENAW ALL DAY...ONLY BOLSTERED BY AN INCREASINGLY FAVORABLE EASTERLY UPSLOPE WIND. WENT WITH DENSE FOG ADVY ALL DAY THERE AND ALSO OVR ALL OF CNTRL LK SUPERIOR AND ADJACENT NSH ZONES FM TIP OF KEWEENAW TO GRAND MARAIS. ELSEWHERE...ALONG LAKE SUPERIOR EAST OF KEWEENAW TO NORTHERN LUCE COUNTY...EXPECT FOG TO BE DENSE THIS MORNING BUT THEN TO TRY TO MIX OUT THIS AFTN WITH LOW LEVEL MIXING OVR LAND. THUS...DID NOT GO WITH DENSE FOG ADVY AWAY FM THE KEWEENAW. ONCE WE GET A HANDLE ON HOW THE FOG IS UNFOLDING THIS MORNING...FURTHER DENSE FOG ADVYS MAY BE NEEDED. MADE APPROPRIATE ADJUSTMENTS TO SKY/WX AND LOWERED TEMPS SOME MORE ALONG THE SHORE WITH PERSISTENT ONSHORE FLOW. && .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW OVER THE NRN TIER CONUS. QUIET NGT OVER THE CWA WITH SFC RDG OVER ONTARIO NOSING TOWARD THE FA AND STABLE AIRMASS WITH WELL DEFINED CAP ARND H7 AS SHOWN ON 00Z INL RAOB/TAMDAR SDNG FM SAW. CONVECTION THAT IMPACTED THE SE ZNS ALG TROF EARLIER IN THE EVNG HAVE WEAKENED/ PUSHED TO THE S WITH THAT TROF. SINCE LLVLS NEVER DRIED SGNFTLY IN THE WAKE OF THE TROF...SOME FOG HAS DVLPD. A PAIR OF SHRTWVS OF INTERNEST NOTED UPSTREAM. THE FIRST OF THESE IS PUSHING INTO THE NRN PLAINS AND CAUSING QUITE A BIT OF SHRA/TSRA IN THE DAKOTAS. HI CLDS IN ADVANCE OF THESE SHRA ARE PUSHING INTO MN. ANOTHER TRAILING SHRTWV IS MOVING EWD ALG THE CNDN BORDER JUST N OF MT. MAIN FCST CONCERNS THIS PACKAGE ARE PCPN CHCS THIS WEEKEND INTO EARLY NEXT WEEK ASSOCIATED WITH COMPLEX INTERACTION OF PAIR OF SHRTWVS UPSTREAM. FOR TDAY...SHRTWV RDG/SFC HI PRES RDG AXIS IS FCST TO BE OVHD THIS MRNG. EXPECT ANY FOG TO BURN OFF QUICKLY WITH RETURN OF DIURNAL HTG. SHRTWV NOW MOVING INTO THE NRN PLAINS IS PROGGED TO REACH NRN MN BY 00Z SUN. LATEST MODEL GUIDANCE HAS TRENDED SLOWER TO BRING DEEP MSTR EWD WITH MORE RESILIENT HI PRES/MID LVL DRY AIR. WL RESTRICT MENTION OF SCHC POPS TO AFT 21Z AND OVER ONLY WRN LK SUP WHERE 12Z ECMWF/00Z GFS SHOW SOME UPR DVGC/DEEP LYR H85-3 QVECTOR CNVGC ARRIVING IN ADVANCE OF THE SHRTWV BY 00Z. OTRW...MIXING TO H775 OR SO ON GFS/NAM FCST SDNGS YIELDS HI TEMPS IN THE MID-UPR 70S AWAY FM LK MODERATION THAT WL BE MAXIMIZED IN AREAS FAVORED BY E-NE WINDS S OF HI PRES CENTER IN ONTARIO. FOR TNGT...00Z NAM/GFS/UKMET SHOW INITIAL SHRTWV APRCHG FM THE W SPLITTING WITH SRN PIECE SUPPORTING MORE SUPPRESSED WARM FNT/SFC LO TRACKING THRU WI THAT WOULD RESULT IN INTERCEPTION OF MOST SGNFT MSTR S OF THE CWA. 00Z CNDN MODEL MORE SIMILAR TO THE 12Z ECMWF SHOWING A MORE COHESIVE SHRTWV COMING RIGHT AT THE FA WITH HIGHER QPF OVER ALL BUT THE ERN ZNS...WHICH ALL GUIDANCE EXCEPT 12Z ECMWF INDICATE WL STAY DRY. DESPITE ITS HIER QPF...EVEN THE 12Z ECMWF HINTS AT WARM FNT WELL TO THE S...WITH APRNT RELIANCE ON UPR DVGC IN RRQ OF SUBTLE H3 JET MAX IN SE CAN TO GENERATE PCPN OVER THE FA WELL N OF THIS BNDRY. OVERALL...CUT POPS A BIT ESPECIALLY OVER E...WHERE EVEN THE STRONGER CNDN MODEL IS DRY THRU 12Z SUN AND ELY FLOW OUT OF DRY HUDSON BAY HI PRES WOULD FURTHER REDUCE PCPN CHCS. SINCE EVEN THE MOISTER ECWMF SHOWS SSI GREATER THAN 0 OVER THE ENTIRE FA... REMOVED ALL MENTION OF TS. TRAILING SHRTWV NOW JUST N OF MT PROGGED TO REACH NRN MN BY 00Z MON. THE APRCH OF THIS SYS WL MAINTAIN UPR TROFFINESS...BUT GUIDANCE (INCLUDING THE 12Z ECMWF) SHOWS MORE OF AN ACYC FLOW TO THE N OF A WEAKER...MORE SUPPRESSED LO FARTHER S. THE 00Z CNDN IS THE ONLY MODEL SHOWING A DEEPER LO FARTHER N WITH A WELL DEFINED CYC NE FLOW. OPTED TO GO WITH A BLANKET 30 POP THRU THE ENTIRE DAY AND ADD A SCHC OF AFTN TS INLAND FM LK MODERATION DESPITE RATHER MODEST LAPSE RATES SHOWN BY GFS FCST SDNGS. NAM FCST DWPTS INTO THE MID 60S SEEM UNRSNBL CONSIDERING PLACEMENT OF WARM FNT TO THE S AND LACK OF ANY STRG LLVL ADVCTN WITH HUDSON BAY HI STILL LINGERING. WL MAINTAIN GOING 30 POP SUN NGT AS SHRTWV/HINT OF H5 THERMAL TROF SWINGS SE ACRS THE UPR LKS... ALBEIT IN ABSENCE OF DIURNAL HTG. HGTS BEGIN TO RISE SLOWLY ON MON ONCE SHRTWV PULLS TO THE E...BUT SLOWED DOWN DEPARTURE OF CHC POPS ON MON TO REFLECT MORE PERSISTENT MID LVL MSTR/LOWER H5 TEMPS SHOWN BY 00Z NAM/GFS/UKMET THRU THE DAY. WL MAINTAINED DRY FCST FOR MON NGT WITH DEPARTURE OF UPR TROF AND DEEP MSTR/LACK OF DIURNAL HTG. COORDINATED WITH DLH/GRB/LOT/APX. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... NOT MUCH RADIATION FOG OVERNIGHT...BUT DENSE FOG THAT FORMED OVR LAKE SUPERIOR IS PUSHING SOUTH AND WILL AFFECT BOTH TAF SITES IN SOME SHAPE THROUGH THE MORNING. BEST CHANCE OF VSBY BLO 1/2SM IS AT KCMX WITH DEVELOPING EAST ONSHORE WIND AND WITH THE KEWEENAW CLOSEST TO THE ADDED MOISTURE OFF LAKE SUPERIOR. HAVE KEPT VLIFR CONDITIONS AT KCMX ALL DAY. MEANWHILE...AT KSAW...EXPECT PRESENT CLEAR SKIES TO RAPIDLY TRANSITION TO AT LEAST IFR BY MID MORNING. DAYTIME MIXING SHOULD TRY TO MIX OUT THE LOW CLOUDS AND MOST LIKELY ANY LWR VSBY BY MID AFTN. LOW CLOUDS MAY HANG AROUND AT CMX INTO THE EVENING...BUT EVENTUALLY EXPECT CLOUDS TO LIFT TO MVFR RANGE TONIGHT. HAVE KEPT ANY PCPN OUT OF FCST TONIGHT AS UNCERTAINTY IS HIGH AS TO WHEATHER ANY PCPN WILL IMPACT TAFS AT ALL. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... FOG IS STUBBORN TO DISSIPATE...BUT IS MOST RESILIENT OVR COOLER WATERS OF ERN LAKE SUPERIOR. EXPECT THE FOG TO GRADUALLY LIFT THROUGH THE DAY WITH INCREASING WINDS AND MIXING. STRONGEST WINDS THROUGH NEXT COUPLE DAYS OCCUR OVR FAR WEST LAKE SUPERIOR WITH NE WINDS FUNNELING DOWN TOWARD HEAD OF LAKE SUPERIOR AS WAVE OF LOW PRESSURE SLIDES BY JUST TO THE SOUTH. SINCE RIDGE OVR LAKE SUPERIOR IS FAIRLY WEAK LEADING TO A WEAKER PRESSURE GRADIENT...WINDS SHOULD NOT EXCEED 20 KNOTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... DENSE FOG ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR MIZ001-003. DENSE FOG ADVISORY UNTIL NOON EDT TODAY FOR MIZ006-007-014-085. LAKE SUPERIOR... DENSE FOG ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR LSZ243>251- 263>267. LAKE MICHIGAN...NONE. && $$ UPDATE...JLA/AJ DISCUSSION...KC AVIATION...JLA MARINE...JLA
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
815 AM EDT SAT JUL 19 2008 .UPDATE... ...DENSE FOG MOVING IN OFF LAKE SUPERIOR... DENSE FOG THAT DEVELOPED OVER THE COLD WATERS OF LAKE SUPERIOR LAST NIGHT IS BEING ADVECTED SOUTH IN A HURRY AS WEAK HIGH PRES CENTER NORTH OF LAKE SUPERIOR DROPS SOUTH. NOT MUCH TO GO ON FM OBSERVATION STANDPOINT...BUT LAST VIS/FOG IMAGERY OF NIGHT SHOWED THE STRATUS/FOG SHIFTING SOUTH AND WEB CAMS FM EAGLE RIVER...COPPER HARBOR...AND AT CENTRAL IN HIGHER TERRAIN OF KEWEENAW COUNTY ALL SHOWED NEAR ZERO VSBY WITHIN LAST HR. FOLLOWED LOW LEVEL RH PROGS FM NAM AS IT HAD A GOOD HANDLE. INDICATIONS ARE THAT THE FOG WILL AFFECT KEWEENAW ALL DAY...ONLY BOLSTERED BY AN INCREASINGLY FAVORABLE EASTERLY UPSLOPE WIND. WENT WITH DENSE FOG ADVY ALL DAY THERE AND ALSO OVR ALL OF CNTRL LK SUPERIOR AND ADJACENT NSH ZONES FM TIP OF KEWEENAW TO GRAND MARAIS. ELSEWHERE...ALONG LAKE SUPERIOR EAST OF KEWEENAW TO NORTHERN LUCE COUNTY...EXPECT FOG TO BE DENSE THIS MORNING BUT THEN TO TRY TO MIX OUT THIS AFTN WITH LOW LEVEL MIXING OVR LAND. THUS...DID NOT GO WITH DENSE FOG ADVY AWAY FM THE KEWEENAW. ONCE WE GET A HANDLE ON HOW THE FOG IS UNFOLDING THIS MORNING...FURTHER DENSE FOG ADVYS MAY BE NEEDED. MADE APPROPRIATE ADJUSTMENTS TO SKY/WX AND LOWERED TEMPS SOME MORE ALONG THE SHORE WITH PERSISTENT ONSHORE FLOW. && .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW OVER THE NRN TIER CONUS. QUIET NGT OVER THE CWA WITH SFC RDG OVER ONTARIO NOSING TOWARD THE FA AND STABLE AIRMASS WITH WELL DEFINED CAP ARND H7 AS SHOWN ON 00Z INL RAOB/TAMDAR SDNG FM SAW. CONVECTION THAT IMPACTED THE SE ZNS ALG TROF EARLIER IN THE EVNG HAVE WEAKENED/ PUSHED TO THE S WITH THAT TROF. SINCE LLVLS NEVER DRIED SGNFTLY IN THE WAKE OF THE TROF...SOME FOG HAS DVLPD. A PAIR OF SHRTWVS OF INTERNEST NOTED UPSTREAM. THE FIRST OF THESE IS PUSHING INTO THE NRN PLAINS AND CAUSING QUITE A BIT OF SHRA/TSRA IN THE DAKOTAS. HI CLDS IN ADVANCE OF THESE SHRA ARE PUSHING INTO MN. ANOTHER TRAILING SHRTWV IS MOVING EWD ALG THE CNDN BORDER JUST N OF MT. MAIN FCST CONCERNS THIS PACKAGE ARE PCPN CHCS THIS WEEKEND INTO EARLY NEXT WEEK ASSOCIATED WITH COMPLEX INTERACTION OF PAIR OF SHRTWVS UPSTREAM. FOR TDAY...SHRTWV RDG/SFC HI PRES RDG AXIS IS FCST TO BE OVHD THIS MRNG. EXPECT ANY FOG TO BURN OFF QUICKLY WITH RETURN OF DIURNAL HTG. SHRTWV NOW MOVING INTO THE NRN PLAINS IS PROGGED TO REACH NRN MN BY 00Z SUN. LATEST MODEL GUIDANCE HAS TRENDED SLOWER TO BRING DEEP MSTR EWD WITH MORE RESILIENT HI PRES/MID LVL DRY AIR. WL RESTRICT MENTION OF SCHC POPS TO AFT 21Z AND OVER ONLY WRN LK SUP WHERE 12Z ECMWF/00Z GFS SHOW SOME UPR DVGC/DEEP LYR H85-3 QVECTOR CNVGC ARRIVING IN ADVANCE OF THE SHRTWV BY 00Z. OTRW...MIXING TO H775 OR SO ON GFS/NAM FCST SDNGS YIELDS HI TEMPS IN THE MID-UPR 70S AWAY FM LK MODERATION THAT WL BE MAXIMIZED IN AREAS FAVORED BY E-NE WINDS S OF HI PRES CENTER IN ONTARIO. FOR TNGT...00Z NAM/GFS/UKMET SHOW INITIAL SHRTWV APRCHG FM THE W SPLITTING WITH SRN PIECE SUPPORTING MORE SUPPRESSED WARM FNT/SFC LO TRACKING THRU WI THAT WOULD RESULT IN INTERCEPTION OF MOST SGNFT MSTR S OF THE CWA. 00Z CNDN MODEL MORE SIMILAR TO THE 12Z ECMWF SHOWING A MORE COHESIVE SHRTWV COMING RIGHT AT THE FA WITH HIGHER QPF OVER ALL BUT THE ERN ZNS...WHICH ALL GUIDANCE EXCEPT 12Z ECMWF INDICATE WL STAY DRY. DESPITE ITS HIER QPF...EVEN THE 12Z ECMWF HINTS AT WARM FNT WELL TO THE S...WITH APRNT RELIANCE ON UPR DVGC IN RRQ OF SUBTLE H3 JET MAX IN SE CAN TO GENERATE PCPN OVER THE FA WELL N OF THIS BNDRY. OVERALL...CUT POPS A BIT ESPECIALLY OVER E...WHERE EVEN THE STRONGER CNDN MODEL IS DRY THRU 12Z SUN AND ELY FLOW OUT OF DRY HUDSON BAY HI PRES WOULD FURTHER REDUCE PCPN CHCS. SINCE EVEN THE MOISTER ECWMF SHOWS SSI GREATER THAN 0 OVER THE ENTIRE FA... REMOVED ALL MENTION OF TS. TRAILING SHRTWV NOW JUST N OF MT PROGGED TO REACH NRN MN BY 00Z MON. THE APRCH OF THIS SYS WL MAINTAIN UPR TROFFINESS...BUT GUIDANCE (INCLUDING THE 12Z ECMWF) SHOWS MORE OF AN ACYC FLOW TO THE N OF A WEAKER...MORE SUPPRESSED LO FARTHER S. THE 00Z CNDN IS THE ONLY MODEL SHOWING A DEEPER LO FARTHER N WITH A WELL DEFINED CYC NE FLOW. OPTED TO GO WITH A BLANKET 30 POP THRU THE ENTIRE DAY AND ADD A SCHC OF AFTN TS INLAND FM LK MODERATION DESPITE RATHER MODEST LAPSE RATES SHOWN BY GFS FCST SDNGS. NAM FCST DWPTS INTO THE MID 60S SEEM UNRSNBL CONSIDERING PLACEMENT OF WARM FNT TO THE S AND LACK OF ANY STRG LLVL ADVCTN WITH HUDSON BAY HI STILL LINGERING. WL MAINTAIN GOING 30 POP SUN NGT AS SHRTWV/HINT OF H5 THERMAL TROF SWINGS SE ACRS THE UPR LKS... ALBEIT IN ABSENCE OF DIURNAL HTG. HGTS BEGIN TO RISE SLOWLY ON MON ONCE SHRTWV PULLS TO THE E...BUT SLOWED DOWN DEPARTURE OF CHC POPS ON MON TO REFLECT MORE PERSISTENT MID LVL MSTR/LOWER H5 TEMPS SHOWN BY 00Z NAM/GFS/UKMET THRU THE DAY. WL MAINTAINED DRY FCST FOR MON NGT WITH DEPARTURE OF UPR TROF AND DEEP MSTR/LACK OF DIURNAL HTG. COORDINATED WITH DLH/GRB/LOT/APX. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... NOT MUCH RADIATION FOG OVERNIGHT...BUT DENSE FOG THAT FORMED OVR LAKE SUPERIOR IS PUSHING SOUTH AND WILL AFFECT BOTH TAF SITES IN SOME SHAPE THROUGH THE MORNING. BEST CHANCE OF VSBY BLO 1/2SM IS AT KCMX WITH DEVELOPING EAST ONSHORE WIND AND WITH THE KEWEENAW CLOSEST TO THE ADDED MOISTURE OFF LAKE SUPERIOR. HAVE KEPT VLIFR CONDITIONS AT KCMX ALL DAY. MEANWHILE...AT KSAW...EXPECT PRESENT CLEAR SKIES TO RAPIDLY TRANSITION TO AT LEAST IFR BY MID MORNING. DAYTIME MIXING SHOULD TRY TO MIX OUT THE LOW CLOUDS AND MOST LIKELY ANY LWR VSBY BY MID AFTN. LOW CLOUDS MAY HANG AROUND AT CMX INTO THE EVENING...BUT EVENTUALLY EXPECT CLOUDS TO LIFT TO MVFR RANGE TONIGHT. HAVE KEPT ANY PCPN OUT OF FCST TONIGHT AS UNCERTAINTY IS HIGH AS TO WHEATHER ANY PCPN WILL IMPACT TAFS AT ALL. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... FOG IS STUBBORN TO DISSIPATE...BUT IS MOST RESILIENT OVR COOLER WATERS OF ERN LAKE SUPERIOR. EXPECT THE FOG TO GRADUALLY LIFT THROUGH THE DAY WITH INCREASING WINDS AND MIXING. STRONGEST WINDS THROUGH NEXT COUPLE DAYS OCCUR OVR FAR WEST LAKE SUPERIOR WITH NE WINDS FUNNELING DOWN TOWARD HEAD OF LAKE SUPERIOR AS WAVE OF LOW PRESSURE SLIDES BY JUST TO THE SOUTH. SINCE RIDGE OVR LAKE SUPERIOR IS FAIRLY WEAK LEADING TO A WEAKER PRESSURE GRADIENT...WINDS SHOULD NOT EXCEED 20 KNOTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... DENSE FOG ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR MIZ001-003. LAKE SUPERIOR... DENSE FOG ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR LSZ243>250- 264>266. LAKE MICHIGAN... NONE. && $$ UPDATE...JLA DISCUSSION...KC AVIATION...JLA MARINE...JLA
AREA FORECAST DISCUSSION
NWS DULUTH MN
1057 AM CDT SAT JUL 19 2008 .DISCUSSION... AN AREA OF MAINLY RAIN WAS MOVING NORTH AND EAST THIS MORNING...AND AT 1545Z WAS COVERING THE BRAINERD LAKES...PINE RIVER...AND GARRISON AREAS. THERE ARE VERY FEW CG STRIKES IN THIS AREA OF RAIN...SO WE TRIMMED BACK THE THUNDER MENTION THIS MORNING. STILL HAVING A TOUGH TIME DETERMINING IF THIS AREA OF RAIN WILL HOLD TOGETHER AS IT GETS DEEPER INTO OUR CWA. IR IMAGERY SHOWS CLOUD TOPS CONTINUE TO WARM...AND AS MENTIONED LIGHTNING ACTIVITY IS LOW. THE SOUTHEAST SIDE OF THE RAIN...HAS ERODED SOME OVER THE PAST FEW SCANS...BUT AREAS FURTHER WEST ARE HOLDING TOGETHER. RUC13 SUGGESTS THIS AREA WILL DIMINISH OVER THE NEXT COUPLE HOURS. THERE IS A DECENT SHORTWAVE MOVING THROUGH HELPING DRIVE THIS ACTIVITY...BUT IT`S MOVING INTO MORE STABLE AIR...AND FROM MODELS AND TAMDAR SOUNDINGS...THERE ISN`T MUCH LLJ SUPPORT THIS MORNING. WE INCREASED POPS FOR A TIME TO CATEGORICAL OVER OUR SOUTHWEST ZONES...AND TO LIKELY JUST WEST OF THE TWIN PORTS UP TOWARD THE FALLS. WE ALSO INCREASED THEM AROUND THE TWIN PORTS AND IRON RANGE...JUST NOT TO LIKELY YET. AS FAR AS THE FOG OVER LAKE SUPERIOR...A SHIP OB NEAR DEVILS ISLAND WAS REPORTING DENSE FOG...AND VISIBLE IMAGERY CONTINUES TO SHOW A LOT OF STRATUS OR FOG FROM ROUGHLY TWO HARBORS EAST TO DEVILS ISLAND AND POINTS NORTH. LAST COUPLE FRAMES OF THE VISIBLE SHOWS THE STRATUS WAS MOVING DOWN THE SHORE NEAR TWO HARBORS. KBFW HAD A CEILING OF 800 FT. WE ISSUED A MWW FOR DENSE FOG OVER LAKE SUPERIOR. DID NOT ISSUE ANYTHING OVER LAND YET. KCMX WHICH WAS DOWN TO 1/4SM EARLIER...HAS INCREASED TO 7SM. THE VSBY WAS STILL P6SM AT KBFW. && POINT TEMPS/POPS... DLH 71 53 68 53 / 50 30 30 30 INL 76 52 77 52 / 60 30 30 10 BRD 78 58 82 57 / 90 30 20 20 HYR 80 55 83 53 / 40 30 30 40 ASX 74 55 73 52 / 30 40 30 40 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...DENSE FOG ADVISORY UNTIL 6 PM CDT THIS AFTERNOON FOR LSZ121- LSZ140-LSZ141-LSZ142-LSZ143-LSZ144-LSZ145-LSZ146-LSZ147- LSZ162. $$ MELDE/CANNON
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
1030 AM EDT SAT JUL 19 2008 .DISCUSSION... ACARS AND RAOBS FROM AROUND THE REGION INDICATE THAT THE STRONG MIDLEVEL INVERSION REMAINS IN PLACE TODAY. THIS WILL SUPPRESS ANY CONVECTION THROUGH THE AFTERNOON. TEMPERATURES ARE ON TRACK AND NO UPDATE WILL BE NEEDED. && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DGS