Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 04/07/13


AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
911 PM MDT SAT APR 6 2013 .UPDATE...SCATTERED SHOWERS DEVELOPING IN THE MOUNTAINS THIS EVENING WITH ISOLATED RAIN SHOWERS OVER THE URBAN CORRIDOR AND NORTHEAST PLAINS. OVERALL CHANGES MINOR...WILL INCREASE POPS FM 10 TO 20 ACROSS THE LOWER ELEVATIONS. && .AVIATION...GUSTY SE WINDS AT KDEN THE RESULT OF AN AREA OF LGT RAIN SHOWERS TO THE SOUTH AND SOUTHEAST. WILL KEEP TEMPO G25 KTS AT KDEN AND KAPA OVER THROUGH 04Z THEN DCRS IT TO LESS THAN 10 KTS. WILL ALSO HAVE VCSH IN THE TAF THE REMAINDER OF THE EVENING AND OVERNIGHT. && .PREV DISCUSSION... /ISSUED 317 PM MDT SAT APR 6 2013/ SHORT TERM...QG LIFT ASSOCIATED WITH UPPER TROUGH TO OUR WEST IS JUST BEGINNING TO IMPINGE ON THE WESTERN SECTIONS OF THE CWA PER THE LATEST RAP ANALYSES. THIS ASCENT WILL SPREAD OVER THE REMAINDER OF THE CWA OVERNIGHT BRINGING A THREAT OF PRECIPITATION TO ALL AREAS...THE HIGHEST IN THE MOUNTAINS. HOWEVER...SATELLITE AND RADAR TRENDS ARE LESS THAN IMPRESSIVE WITH THIS SYSTEM AND HAVE CUT BACK ON POPS/QPFS ACCORDINGLY. AS THE SYSTEM HEADS EAST LATER TONIGHT SOME DESCENT SUBSIDENCE WILL COVER THE CWA FOR MUCH OF SUNDAY`S DAYLIGHT HOURS. LATEST HIRES WINDOW RUNS SHOW ONLY ISOLATED CONVECTIVE ACTIVITY EAST OF THE MOUNTAINS SUNDAY AFTERNOON AND HAVE BACKED OFF POPS THERE DUE TO THIS. MOREOVER... NOT EXPECTING MORE THAN SCATTERED CONVECTIVE ACTIVITY IN THE MOUNTAINS SUNDAY AFTERNOON EITHER. MAXIMUM TEMPERATURES TOMORROW LOOK TO BE CLOSE TO THOSE EXPERIENCED TODAY. LONG TERM...SKIES WILL BE CLEARING SUNDAY NIGHT AS SUBSIDENCE MOVES IN WITH NEAR NORMAL MINIMUM TEMPERATURES. FOCUS TURNS TO MONDAY THROUGH TUESDAY AS AN EARLY SPRING STORM AFFECTS THE STATE. MODELS IN MUCH BETTER AGREEMENT THAN THEY WERE 24 HOURS AGO...BUT STILL HAVE DIFFERENCES THAT MAY AFFECT HOW MUCH SNOW WE SEE. HOWEVER...NO MATTER WHAT SOLUTION IS FOLLOWED...HAVE HIGH CONFIDENCE IN GETTING PRECIPITATION AND GOOD CONFIDENCE IN SIGNIFICANT SNOWFALL TOTALS. WILL START MONDAY MORNING OUT DRY WITH INCREASING HIGH CLOUDS. TEMPERATURES WILL AGAIN CLIMB INTO THE 60S FOR THE PLAINS AND NEAR 50 FOR THE MOUNTAINS. LATE MORNING INTO THE EARLY AFTERNOON...GOOD INSTABILITY WILL ALLOW SHOWERS AND SOME THUNDERSTORMS BEGIN FORMING. A RIDGE OF THETA E WILL BE SLIDING NORTH INTO EASTERN COLORADO AND WESTERN KANSAS WITH CAPES IN THE 800-1200 J/KG RANGE. GOOD SHEAR WILL COMBINE WITH THESE PARAMETERS TO BRING A CHANCE OF STRONG THUNDERSTORMS OVER THE EASTERN PLAINS....MAINLY EAST OF A LINE FROM STERLING TO LIMON. THE STORMS WILL HAVE THE POTENTIAL TO PRODUCE LARGE HAIL AND PERHAPS A TORNADO...THOUGH RIGHT NOW THIS LOOKS TO HAVE A BETTER CHANCE JUST EAST OF OUR FORECAST AREA. MONDAY EVENING...THE STORMS 500 MB LOW CENTER WILL BE OVER THE UT/AZ BORDER MOVING TOWARD THE FOUR CORNERS AREA...WITH THE DEEPENING SURFACE LOW MOVING INTO SOUTHEASTERN COLORADO. THIS WILL BEGIN TO DRAW IN THE COLD AIRMASS FROM THE NORTH. LOW LEVEL MOISTURE FROM THE GULF THAT MOVED IN FROM THE SOUTH EARLIER IN THE DAY WILL COMBINE WITH THE MID LEVEL MOISTURE FROM THE PACIFIC WITH THIS SYSTEM AS THE STORM MOVES OVERHEAD MONDAY NIGHT. PRECIPITATION WILL BEGIN OVER THE PLAINS AS RAIN...AND DEPENDING ON HOW FAST THE COLD AIR MOVES IN...WILL DETERMINE WHEN THE RAIN CHANGES OVER TO SNOW. FOR NOW...FOLLOWING MORE OF THE GFS AND ECMWF SOLUTIONS FOR A QUICKER COOL DOWN COMPARED TO THE NAM. THE NAM SOLUTION OVERALL SEEMS A LITTLE TOO FAR NORTH. SNOW...HEAVY AT TIMES...IS EXPECTED TO SPREAD SOUTH OVER THE AREA MONDAY NIGHT INTO EARLY TUESDAY MORNING. THE BEST UPSLOPE LOOKS TO OCCUR OVER THE NORTHERN HALF OF THE FORECAST AREA...SO WILL EXPECT TO SEE THE HIGHER AMOUNTS NORTH OF I-70...AND LIKELY EAST OF I-76. RIGHT NOW...EXPECT A BROAD BRUSH 5-12 INCHES WITH SOME HIGHER AMOUNTS POSSIBLE OVER THE NORTHERN FOOTHILLS AND URBAN CORRIDOR. HOWEVER DOWN OVER SOUTHERN LINCOLN COUNTY AND IN THE HIGH MOUNTAIN VALLEYS...WILL SEE 2-5 INCHES WHERE THERE WILL BE SLIGHT DOWNSLOPING EFFECTS. THE HARD PART OF THE SNOW FORECAST IS THE TEMPERATURES...AS THE WARM TEMPERATURES OF MONDAY WILL DEFINITELY MELT THE INITIAL SNOW AND AREAS OVER THE EASTERN TO CENTRAL EASTERN PLAINS MAY TAKE A LOT LONGER TO CHANGE OVER TO SNOW. IF WE WERE IN THE DEAD OF WINTER...WE WOULD BE TALKING ABOUT ALMOST 2 FEET OF SNOW. BUT HERE WE ARE IN SPRING WITH WARMING GROUND TEMPERATURES AND PRE-STORM AIR TEMPS IN THE 60S. THIS WILL PLAY WITH THE SNOW- AMOUNT FORECAST COMPARED TO THE QPF. TUESDAY...AS COLD AIR CONTINUES TO POUR IN...NORTH WINDS WILL BE BLOWING AT 15 TO 25 MPH WITH GUSTS UP TO 35 MPH...WHICH WILL PRODUCE BLOWING AND DRIFTING SNOW OVER THE PLAINS. AS THIS EVENT GETS CLOSER...WILL HAVE TO SEE IF AND WHAT KIND OF A HIGHLIGHT WILL BE NEEDED...AS THE WINDS COULD BE STRONG ENOUGH FOR A BLIZZARD...DEPENDING ON HOW THE SYSTEM WRAPS UP. SNOW SHOULD DIMINISH TUESDAY EVENING AS THE SYSTEM MOVES NORTHEAST INTO NEBRASKA. AS SKIES CLEAR AND COLD AIR CONTINUES TO MOVE IN IN NORTHERLY FLOW ALOFT...LOW TEMPERATURES TUESDAY NIGHT WILL LIKELY BE IN THE SINGLE DIGITS TO TEENS AND HIGHS WEDNESDAY WILL STRUGGLE TO GET MUCH ABOVE FREEZING. GFS IS STILL HANGING ON TO ANOTHER WEAK DISTURBANCE MOVING THOUGH THURSDAY....HAVE KEPT THE SLIGHT CHANCE POPS IN THE FORECAST. WILL BEGIN TO RETURN TO NORMAL TEMPERATURES INTO THE WEEKEND WITH A GENERALLY DRY PATTERN...EXCEPT FOR MOUNTAIN SHOWERS IN NORTHWEST FLOW ALOFT. AVIATION...VFR CONDITIONS ARE EXPECTED AT AREA TERMINALS OVERNIGHT AND TOMORROW. THERE STILL MAY BE PUSH OF WESTERLY WINDS LATE THIS AFTERNOON AND EARLY EVENING WITH SPEEDS PERHAPS TOUCHING 25 KNOTS FOR A WHILE. DIURNAL WINDS EXPECTED OVERNIGHT WITH WESTERLY COMPONENTS MOST OF SUNDAY. AS THE UPPER TROUGH MOVES OVERHEAD TONIGHT AND EARLY SUNDAY THERE MAY BE SOME CEILINGS AROUND 8000 FEET ALONG WITH ISOLATED SHOWERS. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...COOPER LONG TERM....KRIEDERMAN AVIATION...COOPER
AREA FORECAST DISCUSSION
NWS PUEBLO CO
558 PM MDT SAT APR 6 2013 .UPDATE... ISSUED AT 558 PM MDT SAT APR 6 2013 ADDED ISOLATED POPS TO SOUTHERN PORTIONS OF THE I-25 CORRIDOR WITH CURRENT RADAR TRENDS INDICATING ECHOES ACROSS THE AREA...THOUGH NOT SURE HOW MUCH IF ANY IS MAKING IT TO THE GROUND WITH DEW PT DEPRESSIONS IN EXCESS OF 20 DEGREE. WILL CONTINUE TO MONITOR RADAR TRENDS THROUGH THE EVENING WITH EMBEDDED SHORT WAVE ACROSS WESTERN COLORADO TRANSLATING ACROSS THE STATE AND LATEST HRRR DATA SPREADING A FEW SHOWERS ACROSS THE PIKES PEAK AND PALMER DVD AROUND MIDNIGHT. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 323 PM MDT SAT APR 6 2013 CURRENTLY...UPPER 60S TO NR 70 FOR THE PLAINS...AND 40S-50S FOR THE MT AREAS. WINDS GENERALLY ARE WELL BEHAVED...BUT WILL SEE A FEW ISOLD WIND GUSTS INT EH 30KT RANGE DUE TO VIRGA. UPSTREAM SHORTWAVE TO OUR N IS EASILY SEEN IN IR IMAGERY ACROSS NRN UT AND ID. THIS WILL CROSS OUR AREA FROM AROUND 03Z-09Z TONIGHT...SO EXPECT THIS TO COINCIDE WITH HIGHEST POPS OVR THE MTS. BEST CHANCE FOR SHOWERS WILL BE OVER THE CONTDVD N OF KMYP...WHERE THE HIGHER ELEVATIONS COULD PICK UP ONE TO THREE INCHES OF SNOW THROUGH TOMORROW FROM SCT SHSN. TOMORROW...WILL START OFF FAIRLY QUIET...THEN COULD SEE A FEW SHOWERS DEVELOP ACROSS THE AREA AFTER ABOUT 21Z...IN RESPONSE TO INCREASING UPPER LIFT FROM THE APPROACHING STORM SYSTEM NOW OVER THE N PACIFIC. INCREASING LAPSE RATES WILL LEAD TO LIFTED INDICES IN THE MINUS TWO RANGE IN THE AFTERNOON...WHICH COULD LEAD TO A FEW LTG STRIKES ACROSS THE AREA. BELIEVE LTG WILL BE RATHER LIMITED...BUT WILL LEAVE MENTION IN THE FORECAST FOR NOW TO PRESERVE CONTINUITY AND COORDINATION WITH SURROUNDING WFOS. TEMPS SHOULD BE FAIRLY CLOSE TO TODAY`S READINGS...MAYBE A COUPLE DEGREES HIGHER AS WRLY FLOW INCREASES. FIRE WX DANGER ALSO IS ON THE INCREASE TOMORROW DUE TO THE INCREASE IN WINDS AND CONTINUED DRY CONDITIONS OVERALL. BEST BET FOR CRITICAL FIRE WX WILL BE OVER THE SAN LUIS VALLEY...WHICH SHOULD SEE GUSTS IN THE 25-35 KT RANGE IN THE AFTERNOON AND EARLY EVE. WILL HOIST THE RED FLAG FOR THE VALLEY FOR THIS PERIOD. ALSO COULD SEE SOME CRITICAL FIRE WX CONDITIONS ACROSS THE LOWER ARKANSAS FROM FREMONT INTO NRN PUEBLO COUNTY...AND IN HUERFANO COUNTY DUE TO GAP FLOW THROUGH LA VETA PASS. AT THIS TIME...LOOKS TOO LIMITED IN SCOPE TO INCLUDE IN THE RED FLAG...BUT MAY HAVE TO BE ADDED BY LATER SHIFTS IF IT APPEARS THAT WINDS WILL BE MORE WIDESPREAD. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 323 PM MDT SAT APR 6 2013 ...POSSIBLE WEATHER TRIFECTA ACROSS SOUTHERN COLORADO MONDAY... MONDAY HAS A LOT OF WEATHER HAZARD POTENTIAL...INCLUDING POSSIBLE SEVERE WEATHER ON THE FAR EASTERN PLAINS...FIRE WEATHER OVER MOST OF THE REST OF THE PLAINS AND WINTER WEATHER IN THE MOUNTAINS. FIRST THE FIRE WEATHER. MONDAY AFTERNOON INTO EARLY EVENING DEFINITELY LOOKS LIKE A HIGH FIRE DANGER PERIOD ACROSS MUCH OF THE SOUTHEAST PLAINS...WITH WINDS...HUMIDITIES AND FUELS ALL MEETING CRITERIA. WITH GUSTS TO 40 MPH...HUMIDITIES BELOW 15 PERCENT AND DRY FUELS... THIS IS DAY WHEN OUTDOOR BURNING SHOULD BE SUSPENDED AND ANY OTHER ACTIVITIES THAT MIGHT SPARK A FIRE SHOULD BE AVOIDED. NOW THE SEVERE POTENTIAL. PARAMETERS ON BOTH MAJOR MODELS USED FOR THIS TIME FRAME ARE INDICATING POSSIBLE SEVERE CONVECTION ACROSS THE FAR EASTERN PLAINS MONDAY AFTERNOON AND EVENING. PARAMETERS INDICATE TORNADO AS WELL AS LARGE HAIL POTENTIAL. THE THREAT AREA CURRENTLY LOOKS EAST OF NORTH-SOUTH LINE THROUGH LA JUNTA. THUNDERSTORMS POSSIBLE ELSEWHERE THIS DAY AS WELL BUT LIKELY NOT SEVERE. NOW THE SNOW. IT WILL SPREAD INTO THE HIGH COUNTRY MONDAY AFTERNOON AND START TO SPREAD ONTO THE ADJACENT PLAINS BY TUESDAY MORNING. STILL BIG UNCERTAINTIES REGARDING THE STORM TRACK. CONTINUES TO LOOK PRETTY CERTAIN FOR GOOD SNOW AND WIND POTENTIAL OVER THE MOUNTAINS AND ALONG THE PALMER DIVIDE...WITH MORE IFFY POTENTIAL ELSEWHERE. REGARDLESS OF THE MODEL...STILL LOOKS LIKE A PERIOD OF AT LEAST SOME SNOW AND WIND FOR MOST OF SOUTHERN COLORADO...INCLUDING THE HIGH MOUNTAIN VALLEYS AND THE SOUTHEAST PLAINS FROM LATE MONDAY NIGHT INTO TUESDAY EVENING. AS WE GET CLOSER...WINTER WEATHER HIGHLIGHTS WILL LIKELY BE NEEDED FOR THE MOUNTAINS AND PALMER DIVIDE AND POSSIBLY ELSEWHERE. STORM SHOULD BE MOSTLY EAST OF THE AREA BY WEDNESDAY EXCEPT FOR LINGERING WIND...COLD AND MOUNTAIN SNOW SHOWERS. STAY TUNED. LW && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 323 PM MDT SAT APR 6 2013 VFR CONDITIONS WILL CONTINUE FOR THE TAF SITES THROUGH TOMORROW. EXPECT SOME ISOLD-SCT SHOWERS PRIMARILY OVER THE MTS TONIGHT AND THEN AGAIN SUN AFTERNOON. AN ISOLD TS IS ALSO POSSIBLE ACROSS THE AREA LATE SUN AFTERNOON...WHICH COULD RESULT IN SOME LOCALIZED STRONG WIND GUSTS. && .PUB WATCHES/WARNINGS/ADVISORIES... FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING FOR COZ228>233-235-237. RED FLAG WARNING FROM 1 PM TO 9 PM MDT SUNDAY FOR COZ224. && $$ UPDATE...MW SHORT TERM...ROSE LONG TERM...LW AVIATION...ROSE
AREA FORECAST DISCUSSION
NWS TAUNTON MA
719 PM EDT SAT APR 6 2013 .SYNOPSIS... HIGH PRESSURE BUILDS OVER NEW ENGLAND TONIGHT AND MOVES OFF TO THE EAST ON SUNDAY. INCREASING SOUTH TO SOUTHWEST WIND WILL BRING MILDER TEMPERATURES FOR THE FIRST PART OF THE WEEK. A COLD FRONT MOVES THROUGH THE REGION TUESDAY. COOLER CONDITIONS WILL THEN MOVE INTO THE REGION MIDWEEK...PRIOR TO ANOTHER STRONGER DISTURBANCE FOR FRIDAY INTO SATURDAY. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... 730 PM UPDATE... FIRE WEATHER HEADLINES HAVE BEEN ALLOWED TO EXPIRE AS WINDS SUBSIDE ACROSS THE REGION. MINOR TWEAKS TO THE FORECAST WITH THE LATEST NEAR-TERM RAP GUIDANCE AND 06.18Z NAM. TRENDS LOOK TO BE ON TRACK. SOME MINOR CHANGES WERE MADE TO THE WIND AND WIND GUSTS FOR SUNDAY...NOTHING MAJOR. PREVIOUS DISCUSSION... PRESSURE RISES ARE ENDING AS HIGH PRESSURE BUILDS OVER NEW ENGLAND. THIS WILL ALLOW FOR MOSTLY CLEAR SKIES THROUGH MIDNIGHT ALONG WITH WINDS BECOMING LIGHT. THIS PERIOD OF RADIATIONAL COOLING COMBINED WITH LOW DEWPOINTS WILL ALLOW TEMPERATURES TO DROP INTO THE 20S AWAY FROM THE COAST. THERE IS A SMALL POTENTIAL FOR MIN TEMPS IN THE UPPER TEENS AROUND THE MONADNOCKS AND PARTS OF NORTHWEST MASS. MID AND HIGH CLOUDS OVER THE GREAT LAKES MARK THE LEADING EDGE OF WARMER AIR MOVING UP THE TRAILING SIDE OF THE HIGH. PER SATELLITE LOOPS...THESE CLOUDS EXTRAPOLATE TO WESTERN NEW ENGLAND AROUND 05Z AND ACROSS THE REMAINDER OF OUR AREA BY MORNING. IF THEY THICKEN FAST ENOUGH...IT MAY KEEP TEMPS FROM COOLING TO THEIR FULL POTENTIAL. GIVEN THE DRYNESS OF THE AIR...ANY SHOWERS FROM THE WARM ADVECTION ALOFT WOULD QUICKLY TURN TO VIRGA. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... SUNDAY... HIGH PRESSURE OFFSHORE AND LOW PRESSURE APPROACHING FROM THE UPPER MIDWEST. THIS WILL BRING FALLING PRESSURE...VALUES OF 1-2 MB/HOUR ARE CURRENTLY OBSERVED OVER THE GREAT LAKES. THIS WILL BRING INCREASING SOUTH AND SOUTHWEST WINDS. THE STRONGEST WINDS ALOFT DON/T REACH SOUTHERN NEW ENGLAND UNTIL LATE AFTERNOON. BUFKIT AND AWIPS SOUNDINGS SHOW 40 KNOTS ALOFT AT THAT TIME...BUT ONLY 30-35 KNOTS OF WIND REACHING THE SURFACE. WE ARE NOT CONSIDERING ANY WIND HEADLINES AT THIS TIME...BUT WILL BE MONITORING. THE BEST CHANCE WOULD BE IN THE WORCESTER HILLS AND EAST SLOPES OF THE BERKSHIRES IN AREAS AT OR ABOVE 2000 FEET MSL. TEMPS IN THE MIXED LAYER AT 925 MB REACH 2-5C...WHICH WOULD SUPPORT MAX TEMPS IN THE 50S. SUNDAY NIGHT... AN APPROACHING COLD FRONT MOVES THROUGH THE REGION OVERNIGHT. THE GFS TIMING SEEMED A TAD FAST...BUT THE OTHER MODELS ALSO DEPICTED A SUNDAY OVERNIGHT/EARLY MONDAY PASSAGE. WITH A WEST-EAST UPPER FLOW AND LIMITED MOISTURE...NOT A LOT OF SUPPORT FOR PCPN. BUT ALL MODELS SHOW A LITTLE PCPN DURING THIS TIME. SO WE HAVE POPS FROM SLIGHT CHANCE TO LOW-END CHANCE DURING THE NIGHT. GUSTY SOUTHWEST WINDS LINGER THE FIRST PART OF THE NIGHT BUT THEN DIMINISH AS THE FRONT MOVES THROUGH. TEMPS ARE A BLEND OF MOS. && .LONG TERM /MONDAY THROUGH SATURDAY/... HEADLINES... * COLD FRONT WITH SHOWERS FOR TUESDAY INTO TUESDAY NIGHT * WET WEATHER REMAINING SOUTH OF NEW ENGLAND FOR MIDWEEK * STRONGER DISTURBANCE FOR FRIDAY INTO SATURDAY */OVERVIEW AND MODEL CONSENSUS... EXCUSING NAO/AO TELECONNECTIONS WITH THEIR WIDESPREAD VARIABILITY THOUGH POSITIVE TREND...OF NOTE IN THE LATEST CPC CLIMATE BRIEFING WERE ROSSBY WAVES INDICATING ANOMALOUS CONVERGENCE AT H2 ACROSS NORTH AMERICA. WHILE BROAD...THIS DOES SUGGEST WEAKER POLAR VORTEX INFLUENCE OVER CANADA AND A MILDER TREND ACROSS THE MID-LATITUDES. IT WOULD SEEM THE ECMWF/ECENS LEANS IN THIS DIRECTION WITH GREATER INFLUENCE OF HIGH PRESSURE. BUT OF NOTE IS HOW OUT OF PHASE IT IS WITH THE 06.12Z GFS/GEFS/CANADIAN BY TUESDAY...WHICH SUPPORT A QUASI- STATIONARY POLAR VORTEX OVER THE SOUTHERN HUDSON BAY REGION OVER THE PROGRESSIVE ECMWF. AS NOTED BY PREVIOUS FORECASTERS...FAVORABILITY IS GIVEN TO THE TUESDAY NIGHT FRONTAL BOUNDARY REMAINING SOUTH WITH CONFLUENT FLOW OVER NEW ENGLAND RATHER THAN ANOMALOUS RIDGING. IT IS MORE IN-LINE WITH WHAT WOULD BE EXPECTED CLIMATOLOGICALLY FOR THIS TIME OF YEAR. WITH THE WPC /WEATHER PREDICTION CENTER/ NOTING THE INCONSISTENT GFS AND GEFS MEAN IN COMPARISON TO THE ECMWF/ECENS...HAVE GONE WITH A BLEND OF NON-GFS DETERMINISTIC GUIDANCE OUT TO 12Z TUESDAY. FROM THEN ON...SUPPORT THE 06.0Z ECMWF WITH HPC/WPC GUIDANCE. */DAY-TO-DAY DETAILS... */MONDAY AND MONDAY NIGHT... DRIVING S/SW FLOW SHOULD MAKE FOR A MILD DAY AHEAD OF THE APPROACHING COLD FRONTAL BOUNDARY. ANTICIPATING A FEW GUSTS DURING THE DAY WITH A WELL-MIXED BOUNDARY LAYER. WILL KEEP INCREASING CLOUDS TOWARDS THE LATTER HALF OF MONDAY...WITH RAIN CHANCES LATE INTO MONDAY NIGHT /06.12Z NAM ESPECIALLY LATE/. */TUESDAY AND TUESDAY NIGHT... COLD FRONT SWEEPS THROUGH THE REGION AND OFFSHORE INTO THE EVENING PERIOD. GUSTY SOUTHWEST WINDS AHEAD WITH WINDS BACKED OUT OF THE NORTHWEST AND POTENTIALLY GUSTING IN WAKE OF THE COLD FRONT /ESPECIALLY CLOSER TO THE SHORES/. VERY FLAT PATTERN THROUGH THE MID- LEVELS WITH LITTLE EVIDENCE OF STRONG LIFT...SCATTERED SHOWERS... LESS INTO WEDNESDAY MORNING. MAY NOT GET TOO MILD DURING THE DAY TUESDAY AS CLOUDS AND SHOWERS COULD PUT A HAMPER ON MIXING-DOWN SIGNIFICANT MID-LEVEL WARMING AT H85 /AROUND +8C BY 18Z TUESDAY/. */WEDNESDAY INTO THURSDAY... IN GOING WITH THE ECMWF...THE COLD FRONT SHOULD BECOME STATIONARY SOUTH OF NEW ENGLAND. ADDITIONAL DISTURBANCES ALONG THE FRONT WILL MAKE FOR CLOUDY AND WET WEATHER...ESPECIALLY ACROSS THE SOUTHERN TIER OF NEW ENGLAND. OTHERWISE...INFLUENTIAL HIGH PRESSURE FROM THE SOUTHERN HUDSON BAY REGION WILL KEEP CONDITIONS DRY AND COOLER WITH PREVAILING NORTHERLY FLOW. */FRIDAY INTO SATURDAY... INSIDE-RUNNER WITH A POSSIBLE TRIPLE POINT LOW ACROSS SOUTHEAST NEW ENGLAND WILL MAKE FOR A WET PERIOD. MILD CONDITIONS ANTICIPATED ALONG AND AHEAD WITH GUSTY SOUTHERLY FLOW. COLDER AND DRIER AIR WITH GUSTY WESTERLY WINDS EXPECTED LATE SATURDAY INTO SATURDAY NIGHT WITH HIGH PRESSURE BUILDING BACK OVER THE REGION FOR THE REMAINDER OF THE WEEKEND. && .AVIATION /23Z SATURDAY THROUGH THURSDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW...HIGH CONFIDENCE THROUGH SUNDAY. MODERATE TO HIGH CONFIDENCE SUNDAY NIGHT. TONIGHT...VFR. MID TO HIGH CLOUDS MOVE IN FROM W-E. SUNDAY...VFR. MID CLOUDS THICKENING AND LOWERING 6-9 KFT. GUSTY SW WINDS 25-30 KTS BY 22Z. SUNDAY NIGHT...VFR. CLOUD BASES 4-6 KFT WITH SCT -RA ALONG A WEAK COLD FRONT. SW WINDS BECOMING W/NW. LOW CONFIDENCE MVFR. KBOS TAF...HIGH CONFIDENCE IN TAF. KBDL TAF...HIGH CONFIDENCE IN TAF. OUTLOOK...MONDAY THROUGH WEDNESDAY... MONDAY INTO MONDAY NIGHT...MODERATE CONFIDENCE. VFR. CLOUDS WITH SHOWERS LATE WILL MAKE FOR MVFR CONDITIONS. TUESDAY INTO TUESDAY NIGHT...MODERATE CONFIDENCE. MVFR. CLOUDS AND SHOWERS. GUSTY SW WINDS AHEAD OF A COLD FRONT SWEEPING DURING THE DAY...OFFSHORE OVERNIGHT. GUSTY NW WINDS TO THE REAR. RETURNING VFR. WEDNESDAY...MODERATE CONFIDENCE. VFR. MVFR POSSIBLE ALONG THE SOUTH-SHORE OF NEW ENGLAND. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. HIGH CONFIDENCE THROUGH SUNDAY NIGHT. THIS EVENING... HIGH PRESSURE BUILDS OVER THE WATERS BRINGING DIMINISHING WIND. SEAS OF 5 FEET HAVE LINGERED OVER THE OUTER WATERS AND SO THE SMALL CRAFT ADVISORY REMAINS FOR A LITTLE WHILE LONGER. TONIGHT... HIGH PRESSURE OVER THE WATERS. EXPECT WINDS AND SEAS WILL BE BELOW SMALL CRAFT LEVELS. SUNDAY AND SUNDAY NIGHT... HIGH PRESSURE MOVES OFFSHORE. STRONG PRESSURE FALLS NOTED OVER THE GREAT LAKES WITH SOUTH WINDS GUSTING TO 30 KNOTS IN PARTS OF THE MIDWEST. MODELS SHOW WINDS OF 30-35 KNOTS MOVING OVER THE WATERS DURING THE DAY AND 40 KNOTS TOWARD EVENING. THE COOL OCEAN WATER MAY STABILIZE THE LOWEST LEVELS FROM GETTING THE FULL WIND...BUT SPEEDS OVER 25 KNOTS ARE REASONABLE AND A FEW GUSTS NEAR GALE FORCE ARE POSSIBLE. A COLD FRONT MOVES TO THE COASTLINE BY DAYBREAK MONDAY. EXPECT SOUTHWEST WINDS AHEAD OF THE FRONT...DIMINISHING LATE AT NIGHT. OUTLOOK...MONDAY THROUGH WEDNESDAY... MONDAY INTO MONDAY NIGHT...MODERATE CONFIDENCE. GUSTY SW WINDS AHEAD OF AN APPROACHING COLD FRONT WILL REMAIN BELOW 25 KTS BUT KEEP SEAS ABOVE 5 FT FOR THE OUTER WATERS. TUESDAY INTO TUESDAY NIGHT...MODERATE CONFIDENCE. COLD FRONT SWEEPS ACROSS THE WATERS TUESDAY NIGHT. GUSTY SW WINDS BELOW 25 KTS AHEAD...TURNING NW TO THE REAR GUSTING BELOW 25 KTS. SEAS ABOVE 5 FT ON THE OUTER WATERS. ATTENDANT SHOWERS BUT NO VISIBILITY RESTRICTIONS. WEDNESDAY...MODERATE CONFIDENCE. FRONT STALLS SOUTH OF THE WATERS. WINDS AND SEAS TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS. SHOWERS POSSIBLE ACROSS THE SOUTHERN WATERS. NO VISIBILITY RESTRICTIONS. && .FIRE WEATHER... SUNDAY... THE DRIEST OF THE AIR IS EXPECTED TO MOVE OFF ON SUNDAY. DEWPOINTS WILL INCREASE THROUGH THE DAY WITH VALUES REACHING THE 20S DURING THE AFTERNOON. EVEN SO...WARMER AIR MOVING IN WILL ALLOW FOR WARMER HIGH TEMPERATURES DURING THE AFTERNOON. THE COMBINATION OF TEMPERATURES IN THE 50S AND DEWPOINTS IN THE 20S STILL BRINGS MINIMUM RELATIVE HUMIDITY VALUES IN THE 20S NORTH OF THE MASS PIKE AND UPPER 20S TO LOWER 30S TO THE SOUTH. SOUTH WINDS WILL INCREASE DURING THE AFTERNOON WITH POTENTIAL FOR GUSTS OF 30-35 MPH... POSSIBLY A LITTLE STRONGER. A CLOUDIER DAY MAY HOLD BACK THE HEATING...THIS WILL NEED TO BE MONITORED. AFTER SPEAKING WITH OUR FIRE WEATHER CONTACTS...WE HAVE DECIDED TO ISSUE A SPECIAL WEATHER STATEMENT HIGHLIGHTED THE ELEVATED FIRE WEATHER POTENTIAL. IF A WARNING IS NEEDED...IT WILL BE ISSUED SUNDAY MORNING. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM 11 AM SUNDAY TO 6 AM EDT MONDAY FOR ANZ231>235-237-251. SMALL CRAFT ADVISORY FROM 11 AM SUNDAY TO 4 AM EDT MONDAY FOR ANZ230-236. SMALL CRAFT ADVISORY UNTIL 6 AM EDT MONDAY FOR ANZ250-254>256. && $$ SYNOPSIS...WTB/SIPPRELL NEAR TERM...WTB/SIPPRELL SHORT TERM...WTB LONG TERM...SIPPRELL AVIATION...WTB/SIPPRELL MARINE...WTB/SIPPRELL FIRE WEATHER...WTB
AREA FORECAST DISCUSSION...UPDATED
NWS TAMPA BAY RUSKIN FL
924 PM EDT SAT APR 6 2013 .UPDATE...THE WEST COAST SEA BREEZE WENT INLAND SLIGHTLY FURTHER THAN ANTICIPATED BY THE MODELS SOUTH OF TAMPA BAY...BUT THE ERLY SURGE WILL TURN WINDS BACK AROUND FOR ALL AREAS IN NEXT HOUR OR TWO. OTHERWISE CURRENT FORECAST IS ON TRACK. ONLY REAL QUESTION IS HOW MUCH MIGHT THE ATL STRATUS HOLD TOGETHER BUT WILL CONTINUE THINKING THAT WILL WILL MOSTLY DISSIPATE ACROSS WRN HALF OF THE PENINSULA. TEMPS WILL REACH THE 50S ACROSS ALL BUT IMMEDIATE COASTAL AREAS AND THEN A WARM DAY INTO THE 80S AREA WIDE TOMORROW. NO UPDATES ARE NEEDED TO GRIDS OR TEXT PRODUCTS. && .AVIATION...MOSTLY VFR CONDITIONS WILL CONTINUE THROUGH THE NEXT 24 HOURS. SCT LOW CLOUDS AND MAYBE SOME PATCHY FOG COULD LEAD TO BRIEF PERIODS OF MVFR OVERNIGHT...WITH CONDITIONS CLEARING AFTER SUNRISE. NORTHEAST FLOW WILL VEER TO MORE EASTERLY OVERNIGHT... WITH A SEABREEZE TURNING WINDS ONSHORE NEAR THE COAST SUNDAY AFTERNOON. && .PREV DISCUSSION... /ISSUED 240 PM EDT SAT APR 6 2013/ SYNOPSIS... 18Z WATER VAPOR AND H4 RAP ANALYSIS SHOW THE IMPRESSIVE APRIL TROUGH RESPONSIBLE FOR THE RAIN AND COLD FRONT ON FRIDAY CONTINUES TO PULL EAST OF THE FL PENINSULA. ASSOCIATED COOL POOL ALOFT IS ALSO QUICKLY TRANSLATING EASTWARD. BEHIND THIS TROUGH...HEIGHT FIELDS ARE REBOUNDING RAPIDLY RESULTING IN MID/UPPER LEVEL RIDGING OVERHEAD BY THIS EVENING. AT THE SURFACE...FORECAST AREA RESIDES ON THE SOUTHERN PERIPHERY OF A LARGE RIDGE EXTENDING DOWN THE EASTERN SEABOARD. TEMPERATURES ARE CLIMBING THROUGH THE 70S UNDER A MIX OF SUN AND A SCT-BKN CUMULUS FIELD. THIS CU FIELD IS FORCED BY THE DIURNAL HEATING INTERACTING WITH A SHALLOW MOIST LAYER BELOW 825MB...AND SHOULD GENERALLY DISSIPATE AS WE HEAD TOWARD MID/LATE EVENING. SHORT TERM (TONIGHT THROUGH MONDAY NIGHT)... NOT MUCH IN THE WAY OF SENSIBLE WEATHER ON THE WAY THROUGH THE EARLY PORTION OF THE FORECAST PERIOD...WITH NO SIGNIFICANT WEATHER POTENTIAL UNTIL NEAR THE END OF THE WEEK. TONIGHT/SUNDAY/SUNDAY NIGHT... WEAK MID/UPPER RIDGE WILL PASS OVER AND EAST OF THE REGION BY SUNDAY MORNING WITH A MORE ZONAL FLOW DEVELOPING ALONG THE NORTHERN GULF COAST AND FL PENINSULA IN IT WAKE. AT THE SURFACE...THE REGION WILL REMAIN ON THE SOUTHERN SIDE OF A RIDGE AXIS EXTENDING DOWN/JUST OFF THE EASTERN CONUS SEABOARD. DRY CONDITIONS WILL BE THE RULE WITH LITTLE TO NO SYNOPTIC FORCING OR AVAILABLE MOISTURE KEEPING POPS NEAR ZERO FOR THE REST OF THE WEEKEND. LOW TEMPERATURES BY LATE TONIGHT WILL BE SEASONABLY COOL WITH MANY INLAND LOCATIONS DROPPING INTO THE 50S...AND THE IMMEDIATE COAST FROM PINELLAS COUNTY SOUTHWARD HOLDING IN THE 60S. SUNDAY WILL FEATURE OF MIX OF SUN AND CLOUDS WITH ANOTHER LATE MORNING/AFTERNOON EXPANDING CU FIELD. EFFICIENT MIXING UP TO AROUND 850-825MB WHERE TEMPS WILL BE AROUND 10-12C SHOULD ALLOW MANY LOCATIONS AWAY FROM THE BEACHES TO APPROACH 80 OR EVEN CLIMB INTO THE LOWER 80S SOUTH OF I-4. THE IMMEDIATE COAST MAY END UP SEVERAL DEGREES COOLER WHERE FEEBLE AFTERNOON SEA-BREEZE CIRCULATIONS WILL TURN WINDS ONSHORE FOR PART OF THE PEAK HEATING PERIOD. SUNDAY NIGHT WILL FEATURE MOSTLY CLEAR SKIES AND TEMPERATURES A FEW DEGREES COOLER THAN TONIGHT. MAINLY LOOKING FOR LOWS DROPPING INTO THE UPPER 50S TO LOWER 60S BY SUNRISE...WITH SOME MIDDLE 50S FOR THE NORMALLY COLDER SPOTS ALONG THE NATURE COAST. MONDAY-TUESDAY... THE WARMING TREND CONTINUES INTO THE EARLY PORTION OF THE WEEK. TEMPERATURES WILL QUICKLY RISE BACK ABOVE NORMAL FOR MANY SPOTS...ESPECIALLY BY TUESDAY. GFS/ECMWF SHOW ZONAL FLOW AGAIN BECOMING WEAKLY RIDGED IN THE MID/UPPER LEVELS WHILE THE SURFACE RIDGE AXIS SINKS EVER SO SLOWLY SOUTHWARD TOWARD THE GA/SC COAST. EFFICIENT MIXING...STRONG APRIL SUN...AND A WARMING LOW LEVEL COLUMN (850MB TEMPS 12-14C) WILL ALLOW MANY LOCATIONS AWAY FROM THE COAST TO MIX OUT INTO THE LOWER 80...AND EVEN SO MIDDLE 80S SOUTH OF TAMPA MONDAY AFTERNOON. MANY SPOTS ARE FORECAST TO REACH THE MIDDLE 80S AWAY FROM THE BEACHES FOR TUESDAY AFTERNOON. ENJOY THE PLEASANT APRIL WEATHER! LONG TERM (TUESDAY THROUGH NEXT SATURDAY)... MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT THROUGH WEDNESDAY OR WEDNESDAY NIGHT...WITH SOLUTIONS THEN DIVERGING SIGNIFICANTLY WITH RESPECT TO THE NEXT COLD FRONT LATE NEXT WEEK AND INTO THE UPCOMING WEEKEND. THE 00Z CANADIAN AND 00Z ECMWF SOLUTIONS SHOW A MUCH LESS PROGRESSIVE PATTERN...WITH THE 00Z GFS AND 00Z UKMET SOLUTIONS MUCH MORE AGGRESSIVE MOVING THE NEXT COLD FRONT INTO THE FORECAST AREA AS EARLY AS THURSDAY NIGHT. WILL TAKE A BLENDED FORECAST APPROACH FOR NOW AS BOTH SOLUTIONS SEEM TO HAVE SOME MERIT GIVEN THE SPREAD IN THE GFS ENSEMBLE SUITE. OVERALL...WILL KEEP THE FORECAST RAIN FREE THROUGH TUESDAY NIGHT...WITH SLIGHT CHANCE LOW CHANCE POPS IN THE FORECAST EACH DAY WEDNESDAY THROUGH SATURDAY FOR PRIMARILY AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS. TEMPERATURES ARE EXPECTED TO RUN ABOVE NORMAL THROUGH FRIDAY BEFORE SETTLING BACK CLOSER TO SEASONAL LEVELS NEXT WEEKEND. AVIATION... VFR CONDITIONS WITH OCNL BKN VFR CIGS. LIMITED LATE NIGHT BR POSSIBLE AT LAL/PGD/RSW. NE OR NORTH WINDS AND GUST AT TIMES DIMINISH OVER NIGHT AND BECOME NE AND EAST. MARINE... THE REGION WILL REMAIN ON THE SOUTHERN SIDE OF A RIDGE AXIS ALONG THE EASTERN SEABOARD THROUGH THE EARLY PORTION OF NEXT WEEK. THIS POSITION WITH RESPECT TO THE RIDGE WILL PROVIDE A GENERAL EAST TO SOUTHEAST FLOW REGIME ACROSS THE EASTERN GULF OF MEXICO...OUTSIDE OF LOCAL ONSHORE FLOW DURING THE AFTERNOON ASSOCIATED WITH ANY SEA-BREEZE CIRCULATIONS. FIRE WEATHER... NO SIGNIFICANT FIRE WEATHER CONCERNS ARE ANTICIPATED OVER THE NEXT COUPLE OF DAYS. RELATIVE HUMIDITY VALUES AWAY FROM THE COAST ARE FORECAST TO BRIEFLY APPROACH 35 PERCENT BOTH SUNDAY AND MONDAY DURING THE AFTERNOON...HOWEVER NO CRITICAL DURATIONS OF LOW RELATIVE HUMIDITY ARE EXPECTED AND RED FLAG CONDITIONS APPEAR UNLIKELY. INCREASING LOW LEVEL MOISTURE FOR THE MIDDLE PORTION OF THE WEEK SHOULD PREVENT CRITICAL LEVELS OF RELATIVE HUMIDITY FOR ALL ZONES. && .PRELIMINARY POINT TEMPS/POPS... TPA 61 78 63 83 / 10 0 10 0 FMY 61 82 63 85 / 10 10 0 0 GIF 59 82 61 85 / 10 10 0 10 SRQ 60 80 61 82 / 10 10 0 0 BKV 52 82 55 84 / 10 10 10 10 SPG 64 79 66 83 / 10 10 0 0 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ SHORT TERM/MARINE/FIRE WEATHER...88/GITTINGER LONG TERM/AVIATION...18/FLEMING
AREA FORECAST DISCUSSION
NWS MIAMI FL
134 PM EDT FRI APR 5 2013 .AVIATION... MOSTLY VFR CONDITIONS WITH BKN-OVC100 AND OCCASIONAL BKN035 WITH A PASSING SHRA. SOME LIGHT RAIN IS ALSO POSSIBLE UNTIL EARLY EVENING WHEN CLOUDS MOVE OUT TO THE EAST OF THE PENINSULA. SURFACE WIND HAS BEEN WEAKER THAN EARLIER THINKING DUE TO RAIN COOLED AIRMASS ALONG WITH OVERCAST MID TO HIGH CLOUDS. COULD HAVE SOME GUSTS OVER 12KT WITH SW FLOW THEN VEERING TO THE NW BEHIND THE COLD FRONT BECOMING NNE AFT 12-13Z SATURDAY. KOB && .PREV DISCUSSION... /ISSUED 953 AM EDT FRI APR 5 2013/ UPDATE... CURRENT WAVE OF PRECIPITATION THIS MORNING ACROSS LAKE OKEECHOBEE TO SOUTHWEST FLORIDA, THEN DOWN INTO THE SE GULF OF MEXICO MAKING STEADY EASTWARD PROGRESS AHEAD OF THE POWERFUL SHORTWAVE TROUGH OVER THE EASTERN GULF OF MEXICO. ATMOSPHERE HAS STABILIZED IN THE LOW LEVELS IN THE WAKE OF THE OVERNIGHT AND EARLY MORNING CONVECTION, WHICH IS ACTING TO LIMIT THE INTENSITY OF THE ACTIVITY CURRENTLY MOVING OVER THE AREA. SOUTHERLY FLOW TRYING TO DESTABILIZE THE LOW LEVELS THIS MORNING, BUT OVERCAST CLOUD SHIELD WILL MITIGATE ANY SIGNIFICANT WARMING AND SPC HAS APPROPRIATELY DOWNPLAYED THE SEVERE THREAT ACROSS SOUTH FLORIDA TODAY. FORECAST UPDATE HAS NUMEROUS SHOWERS AND ISOLATED TSTMS, GRADUALLY TAPERING OFF FROM NW TO SE AS THE COLD FRONT CURRENTLY APPROACHING THE TAMPA BAY REGION MOVES INTO THE AREA THIS AFTERNOON. LOWERED TEMPERATURES A FEW DEGREES DUE TO COOLER READINGS THIS MORNING AND EXTENSIVE CLOUD COVER. INTERESTING TIDBIT: A "WAKE LOW" FEATURE WAS NOTED EARLY THIS MORNING OVER PARTS OF SOUTH FLORIDA WHICH HELPED TO PRODUCE NON- THUNDERSTORM WIND GUSTS OF 35 TO 45 MPH IN THE NAPLES AREA AS WELL AS LAKE OKEECHOBEE AND PARTS OF THE PALM BEACHES. THIS IS THE SAME TYPE OF FEATURE WHICH PRODUCED THE STRONG WINDS IN THE MOBILE AREA BACK ON WEDNESDAY, AND THIS HAS BEEN NOTED IN PAST SPRINGTIME CONVECTION EVENTS OVER SOUTH FLORIDA AND OTHER PARTS OF THE SOUTHERN UNITED STATES. /MOLLEDA PREV DISCUSSION... /ISSUED 831 AM EDT FRI APR 5 2013/ AVIATION... A BAND OF LIGHT RAIN WILL MOVE ACROSS SOUTH FLORIDA INTO EARLY THIS AFTERNOON WITH SOME MVFR CIGS/VISIBILITIES BUT MOSTLY VFR. IT IS POSSIBLE DEPENDING ON ANY BREAKS IN THE CLOUD COVER THAT A FEW THUNDERSTORMS COULD ALSO DEVELOP BY EARLY THIS AFTERNOON AHEAD OF THE FRONT. THESE CONDITIONS WILL DIMINISH THIS AFTERNOON AS THE COLD FRONT CLEARS THE PENINSULA. SURFACE WIND WILL BE SSW TO SW INCREASING IN SPEEDS AND OCCASIONALLY GUSTING OVER 20KT AFT 13-14Z SHIFTING TO THE NORTHWEST BEHIND THE FRONT. KOB PREV DISCUSSION... /ISSUED 343 AM EDT FRI APR 5 2013/ DISCUSSION... AN MCS WAS MOVING ACROSS THE EASTERN GULF AND SOUTH FLORIDA EARLY THIS MORNING. AN UPPER LEVEL LOW WAS MOVING EAST ACROSS ALABAMA...WITH BROAD SURFACE LOW PRESSURE AREAS FROM NORTHERN FLORIDA NORTHWARD TO OFF THE COAST OF NORTH CAROLINA. GLOBAL MODELS ARE NOT HANDLING THE CURRENT SITUATION WELL...SO FOLLOWED CLOSER TO THE HRRR OUTPUT THROUGH THE AFTERNOON. THE ATMOSPHERE OVER SOUTH FLORIDA IS EXPECTED TO BECOME WORKED OVER FROM THIS MCS...WITH MUCH MORE STABLE CONDITIONS. CLOUD COVER WILL BLANKET THE REGION FOR MUCH OF THE DAY. SO THE SEVERE THREAT APPEARS TO HAVE DIMINISHED...WITH THE LAST STRONG STORMS ACROSS THE FAR SOUTHEASTERN PORTIONS OF MIAMI DADE COUNTY EARLY THIS MORNING. SO LIGHT/MODERATE RAIN WITH A FEW EMBEDDED THUNDERSTORMS ARE ALL THAT IS EXPECTED THROUGH THE MID/LATE AFTERNOON...BEFORE THE COLD FRONT PUSHES THROUGH THE REGION. UNDERCUT MAV/MET TEMPERATURES AT MOST LOCATIONS TODAY DUE TO THE EXPECTED CLOUD COVER AND RAIN. A FEW LINGERING SHOWERS ARE POSSIBLE INTO THE EARLY EVENING. OTHERWISE...DRIER AND COOLER CONDITIONS ARE EXPECTED OVER SOUTH FLORIDA TONIGHT. THE WEEKEND LOOKS LIKE IT WILL BE A PLEASANT ONE WITH TEMPERATURES NEAR NORMAL FOR EARLY APRIL. A LIGHT TO MODERATE NORTHEASTERLY FLOW WILL PREVAIL ON SATURDAY...WITH WINDS SHIFTING TO THE EAST ON SUNDAY AS HIGH PRESSURE MOVES INTO THE WESTERN ATLANTIC OFF THE EASTERN CONUS. HIGH PRESSURE WILL REMAIN OVER THE WESTERN ATLANTIC THROUGH THE MIDDLE OF THE WEEK...WITH LOW LEVEL MOISTURE RETURNING TO THE REGION. HIGHS WILL REMAIN IN THE LOW 80S EAST TO THE MID TO UPPER 80S TOWARD THE GULF COAST. OVERNIGHT LOW TEMPERATURES WILL INCREASE TO THE LOWER 70S FOR THE EAST COAST METRO AREAS. A FEW STREAMER SHOWERS WILL BE POSSIBLE EACH DAY FROM TUESDAY THROUGH THE END OF THE WEEK. AVIATION...06Z TAFS. MATURE MCS MOVING ACROSS THE EASTERN GULF AND ACROSS SOUTH FLORIDA EARLY THIS MORNING. STRONG TO SEVERE STORMS ARE POSSIBLE AT KFXE SOUTHWARD ON THE EAST COAST OVER THE NEXT FEW HOURS. PREVAILING MVFR CONDITIONS ARE EXPECTED FOR MOST OF THE EAST COAST TAF SITES THROUGH THE OVERNIGHT HOURS...WITH IFR CONDITIONS POSSIBLE IN THUNDERSTORMS. KAPF IS IN THE RAIN SHIELD ON THE NORTH SIDE OF THE MCS...AND LIGHT/MODERATE RAIN WITH A FEW HIGH BASED LIGHTNING STRIKES WILL CONTINUE THROUGH THE MORNING HOURS. LIGHT/MODERATE RAIN IS EXPECTED AFTER 10-12Z ACROSS THE REGION AS THE MCS MOVES THROUGH AND SOUTH FLORIDA GETS WORKED OVER. AT THIS TIME IS IT DIFFICULT TO SAY WHETHER THERE WILL BE ANY REGENERATION OF THUNDERSTORMS BY THE AFTERNOON HOURS DUE TO ALL THE CLOUD COVER. BASED OFF OF LATEST GUIDANCE...WILL ONLY SHOW RAIN AFTER 12-14Z...WITH CONDITIONS IMPROVING BY MID/LATE AFTERNOON. THE FRONT IS EXPECTED TO PASS THROUGH THE REGION 18-21Z...WITH LIGHT/MODERATE NORTHWESTERLY FLOW THROUGH THE END OF THE TAF PERIOD. MARINE... LATEST GUIDANCE INDICATES THAT WINDS ACROSS THE LOCAL GULF AND ATLANTIC WATERS COULD REACH AROUND 20 KNOTS THIS MORNING AND SEAS ACROSS THE OFF SHORE GULF WATERS COULD REACH NEAR 7 FEET. A SMALL CRAFT ADVISORY IS IN EFFECT THROUGH 00Z THIS EVENING FOR ALL OF THE LOCAL WATERS. A COLD FRONT WILL MOVE THROUGH THE REGION LATE THIS AFTERNOON...WITH WINDS SHIFTING TO THE NORTHWEST BEHIND THE FRONT. NORTHEAST WINDS 15-20 KNOTS ARE EXPECTED ON SATURDAY...WITH EASTERLY WINDS 10-15 KNOTS ON SUNDAY. EAST TO SOUTHEAST WINDS ARE THEN EXPECTED THROUGH THE WEEK AS HIGH PRESSURE BUILDS ACROSS THE WESTERN ATLANTIC. FIRE WEATHER... MUCH NEEDED RAINFALL WILL CONTINUE TO FALL ACROSS MUCH OF THE REGION THROUGH THE DAY TODAY. A FEW EMBEDDED THUNDERSTORMS ARE POSSIBLE INTO THE AFTERNOON. A COLD FRONT WILL MOVE THROUGH THE REGION LATE THIS AFTERNOON INTO THIS EVENING...WITH DRIER AND COOLER CONDITIONS EXPECTED TONIGHT. MINIMUM RELATIVE HUMIDITY VALUES AND SATURDAY ARE EXPECTED TO REMAIN JUST ABOVE CRITICAL VALUES ACROSS THE INTERIOR WEST. HIGH PRESSURE WILL THEN BUILD ACROSS THE WESTERN ATLANTIC SUNDAY THROUGH THE MIDDLE OF THE WEEK...WITH LOW LEVEL MOISTURE RETURNING TO SOUTH FLORIDA. && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR BISCAYNE BAY-COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL OUT 20 NM-COASTAL WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL OUT 20 NM-LAKE OKEECHOBEE-WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM TO THE TERRITORIAL WATERS OF THE BAHAMAS-WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL EXTENDING FROM 20 NM TO 60 NM. GM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR COASTAL WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM- COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT 20 NM-GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL EXTENDING FROM 20 TO 60 NM. && $$
AREA FORECAST DISCUSSION
NWS MIAMI FL
953 AM EDT FRI APR 5 2013 .UPDATE... CURRENT WAVE OF PRECIPITATION THIS MORNING ACROSS LAKE OKEECHOBEE TO SOUTHWEST FLORIDA, THEN DOWN INTO THE SE GULF OF MEXICO MAKING STEADY EASTWARD PROGRESS AHEAD OF THE POWERFUL SHORTWAVE TROUGH OVER THE EASTERN GULF OF MEXICO. ATMOSPHERE HAS STABILIZED IN THE LOW LEVELS IN THE WAKE OF THE OVERNIGHT AND EARLY MORNING CONVECTION, WHICH IS ACTING TO LIMIT THE INTENSITY OF THE ACTIVITY CURRENTLY MOVING OVER THE AREA. SOUTHERLY FLOW TRYING TO DESTABILIZE THE LOW LEVELS THIS MORNING, BUT OVERCAST CLOUD SHIELD WILL MITIGATE ANY SIGNIFICANT WARMING AND SPC HAS APPROPRIATELY DOWNPLAYED THE SEVERE THREAT ACROSS SOUTH FLORIDA TODAY. FORECAST UPDATE HAS NUMEROUS SHOWERS AND ISOLATED TSTMS, GRADUALLY TAPERING OFF FROM NW TO SE AS THE COLD FRONT CURRENTLY APPROACHING THE TAMPA BAY REGION MOVES INTO THE AREA THIS AFTERNOON. LOWERED TEMPERATURES A FEW DEGREES DUE TO COOLER READINGS THIS MORNING AND EXTENSIVE CLOUD COVER. INTERESTING TIDBIT: A "WAKE LOW" FEATURE WAS NOTED EARLY THIS MORNING OVER PARTS OF SOUTH FLORIDA WHICH HELPED TO PRODUCE NON- THUNDERSTORM WIND GUSTS OF 35 TO 45 MPH IN THE NAPLES AREA AS WELL AS LAKE OKEECHOBEE AND PARTS OF THE PALM BEACHES. THIS IS THE SAME TYPE OF FEATURE WHICH PRODUCED THE STRONG WINDS IN THE MOBILE AREA BACK ON WEDNESDAY, AND THIS HAS BEEN NOTED IN PAST SPRINGTIME CONVECTION EVENTS OVER SOUTH FLORIDA AND OTHER PARTS OF THE SOUTHERN UNITED STATES. /MOLLEDA && .PREV DISCUSSION... /ISSUED 831 AM EDT FRI APR 5 2013/ AVIATION... A BAND OF LIGHT RAIN WILL MOVE ACROSS SOUTH FLORIDA INTO EARLY THIS AFTERNOON WITH SOME MVFR CIGS/VISIBILITIES BUT MOSTLY VFR. IT IS POSSIBLE DEPENDING ON ANY BREAKS IN THE CLOUD COVER THAT A FEW THUNDERSTORMS COULD ALSO DEVELOP BY EARLY THIS AFTERNOON AHEAD OF THE FRONT. THESE CONDITIONS WILL DIMINISH THIS AFTERNOON AS THE COLD FRONT CLEARS THE PENINSULA. SURFACE WIND WILL BE SSW TO SW INCREASING IN SPEEDS AND OCCASIONALLY GUSTING OVER 20KT AFT 13-14Z SHIFTING TO THE NORTHWEST BEHIND THE FRONT. KOB PREV DISCUSSION... /ISSUED 343 AM EDT FRI APR 5 2013/ DISCUSSION... AN MCS WAS MOVING ACROSS THE EASTERN GULF AND SOUTH FLORIDA EARLY THIS MORNING. AN UPPER LEVEL LOW WAS MOVING EAST ACROSS ALABAMA...WITH BROAD SURFACE LOW PRESSURE AREAS FROM NORTHERN FLORIDA NORTHWARD TO OFF THE COAST OF NORTH CAROLINA. GLOBAL MODELS ARE NOT HANDLING THE CURRENT SITUATION WELL...SO FOLLOWED CLOSER TO THE HRRR OUTPUT THROUGH THE AFTERNOON. THE ATMOSPHERE OVER SOUTH FLORIDA IS EXPECTED TO BECOME WORKED OVER FROM THIS MCS...WITH MUCH MORE STABLE CONDITIONS. CLOUD COVER WILL BLANKET THE REGION FOR MUCH OF THE DAY. SO THE SEVERE THREAT APPEARS TO HAVE DIMINISHED...WITH THE LAST STRONG STORMS ACROSS THE FAR SOUTHEASTERN PORTIONS OF MIAMI DADE COUNTY EARLY THIS MORNING. SO LIGHT/MODERATE RAIN WITH A FEW EMBEDDED THUNDERSTORMS ARE ALL THAT IS EXPECTED THROUGH THE MID/LATE AFTERNOON...BEFORE THE COLD FRONT PUSHES THROUGH THE REGION. UNDERCUT MAV/MET TEMPERATURES AT MOST LOCATIONS TODAY DUE TO THE EXPECTED CLOUD COVER AND RAIN. A FEW LINGERING SHOWERS ARE POSSIBLE INTO THE EARLY EVENING. OTHERWISE...DRIER AND COOLER CONDITIONS ARE EXPECTED OVER SOUTH FLORIDA TONIGHT. THE WEEKEND LOOKS LIKE IT WILL BE A PLEASANT ONE WITH TEMPERATURES NEAR NORMAL FOR EARLY APRIL. A LIGHT TO MODERATE NORTHEASTERLY FLOW WILL PREVAIL ON SATURDAY...WITH WINDS SHIFTING TO THE EAST ON SUNDAY AS HIGH PRESSURE MOVES INTO THE WESTERN ATLANTIC OFF THE EASTERN CONUS. HIGH PRESSURE WILL REMAIN OVER THE WESTERN ATLANTIC THROUGH THE MIDDLE OF THE WEEK...WITH LOW LEVEL MOISTURE RETURNING TO THE REGION. HIGHS WILL REMAIN IN THE LOW 80S EAST TO THE MID TO UPPER 80S TOWARD THE GULF COAST. OVERNIGHT LOW TEMPERATURES WILL INCREASE TO THE LOWER 70S FOR THE EAST COAST METRO AREAS. A FEW STREAMER SHOWERS WILL BE POSSIBLE EACH DAY FROM TUESDAY THROUGH THE END OF THE WEEK. AVIATION...06Z TAFS. MATURE MCS MOVING ACROSS THE EASTERN GULF AND ACROSS SOUTH FLORIDA EARLY THIS MORNING. STRONG TO SEVERE STORMS ARE POSSIBLE AT KFXE SOUTHWARD ON THE EAST COAST OVER THE NEXT FEW HOURS. PREVAILING MVFR CONDITIONS ARE EXPECTED FOR MOST OF THE EAST COAST TAF SITES THROUGH THE OVERNIGHT HOURS...WITH IFR CONDITIONS POSSIBLE IN THUNDERSTORMS. KAPF IS IN THE RAIN SHIELD ON THE NORTH SIDE OF THE MCS...AND LIGHT/MODERATE RAIN WITH A FEW HIGH BASED LIGHTNING STRIKES WILL CONTINUE THROUGH THE MORNING HOURS. LIGHT/MODERATE RAIN IS EXPECTED AFTER 10-12Z ACROSS THE REGION AS THE MCS MOVES THROUGH AND SOUTH FLORIDA GETS WORKED OVER. AT THIS TIME IS IT DIFFICULT TO SAY WHETHER THERE WILL BE ANY REGENERATION OF THUNDERSTORMS BY THE AFTERNOON HOURS DUE TO ALL THE CLOUD COVER. BASED OFF OF LATEST GUIDANCE...WILL ONLY SHOW RAIN AFTER 12-14Z...WITH CONDITIONS IMPROVING BY MID/LATE AFTERNOON. THE FRONT IS EXPECTED TO PASS THROUGH THE REGION 18-21Z...WITH LIGHT/MODERATE NORTHWESTERLY FLOW THROUGH THE END OF THE TAF PERIOD. MARINE... LATEST GUIDANCE INDICATES THAT WINDS ACROSS THE LOCAL GULF AND ATLANTIC WATERS COULD REACH AROUND 20 KNOTS THIS MORNING AND SEAS ACROSS THE OFF SHORE GULF WATERS COULD REACH NEAR 7 FEET. A SMALL CRAFT ADVISORY IS IN EFFECT THROUGH 00Z THIS EVENING FOR ALL OF THE LOCAL WATERS. A COLD FRONT WILL MOVE THROUGH THE REGION LATE THIS AFTERNOON...WITH WINDS SHIFTING TO THE NORTHWEST BEHIND THE FRONT. NORTHEAST WINDS 15-20 KNOTS ARE EXPECTED ON SATURDAY...WITH EASTERLY WINDS 10-15 KNOTS ON SUNDAY. EAST TO SOUTHEAST WINDS ARE THEN EXPECTED THROUGH THE WEEK AS HIGH PRESSURE BUILDS ACROSS THE WESTERN ATLANTIC. FIRE WEATHER... MUCH NEEDED RAINFALL WILL CONTINUE TO FALL ACROSS MUCH OF THE REGION THROUGH THE DAY TODAY. A FEW EMBEDDED THUNDERSTORMS ARE POSSIBLE INTO THE AFTERNOON. A COLD FRONT WILL MOVE THROUGH THE REGION LATE THIS AFTERNOON INTO THIS EVENING...WITH DRIER AND COOLER CONDITIONS EXPECTED TONIGHT. MINIMUM RELATIVE HUMIDITY VALUES AND SATURDAY ARE EXPECTED TO REMAIN JUST ABOVE CRITICAL VALUES ACROSS THE INTERIOR WEST. HIGH PRESSURE WILL THEN BUILD ACROSS THE WESTERN ATLANTIC SUNDAY THROUGH THE MIDDLE OF THE WEEK...WITH LOW LEVEL MOISTURE RETURNING TO SOUTH FLORIDA. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 77 61 77 67 / 70 10 0 - FORT LAUDERDALE 78 65 79 69 / 70 10 0 - MIAMI 77 64 79 68 / 70 20 0 - NAPLES 73 58 81 62 / 70 10 0 - && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR BISCAYNE BAY-COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL OUT 20 NM-COASTAL WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL OUT 20 NM-LAKE OKEECHOBEE-WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM TO THE TERRITORIAL WATERS OF THE BAHAMAS-WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL EXTENDING FROM 20 NM TO 60 NM. GM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR COASTAL WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM- COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT 20 NM-GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL EXTENDING FROM 20 TO 60 NM. && $$ PUBLIC/MARINE...59/MOLLEDA AVIATION/RADAR/FIRE...30/KOB
AREA FORECAST DISCUSSION
NWS MIAMI FL
831 AM EDT FRI APR 5 2013 .AVIATION... A BAND OF LIGHT RAIN WILL MOVE ACROSS SOUTH FLORIDA INTO EARLY THIS AFTERNOON WITH SOME MVFR CIGS/VISIBILITIES BUT MOSTLY VFR. IT IS POSSIBLE DEPENDING ON ANY BREAKS IN THE CLOUD COVER THAT A FEW THUNDERSTORMS COULD ALSO DEVELOP BY EARLY THIS AFTERNOON AHEAD OF THE FRONT. THESE CONDITIONS WILL DIMINISH THIS AFTERNOON AS THE COLD FRONT CLEARS THE PENINSULA. SURFACE WIND WILL BE SSW TO SW INCREASING IN SPEEDS AND OCCASIONALLY GUSTING OVER 20KT AFT 13-14Z SHIFTING TO THE NORTHWEST BEHIND THE FRONT. KOB && .PREV DISCUSSION... /ISSUED 343 AM EDT FRI APR 5 2013/ DISCUSSION... AN MCS WAS MOVING ACROSS THE EASTERN GULF AND SOUTH FLORIDA EARLY THIS MORNING. AN UPPER LEVEL LOW WAS MOVING EAST ACROSS ALABAMA...WITH BROAD SURFACE LOW PRESSURE AREAS FROM NORTHERN FLORIDA NORTHWARD TO OFF THE COAST OF NORTH CAROLINA. GLOBAL MODELS ARE NOT HANDLING THE CURRENT SITUATION WELL...SO FOLLOWED CLOSER TO THE HRRR OUTPUT THROUGH THE AFTERNOON. THE ATMOSPHERE OVER SOUTH FLORIDA IS EXPECTED TO BECOME WORKED OVER FROM THIS MCS...WITH MUCH MORE STABLE CONDITIONS. CLOUD COVER WILL BLANKET THE REGION FOR MUCH OF THE DAY. SO THE SEVERE THREAT APPEARS TO HAVE DIMINISHED...WITH THE LAST STRONG STORMS ACROSS THE FAR SOUTHEASTERN PORTIONS OF MIAMI DADE COUNTY EARLY THIS MORNING. SO LIGHT/MODERATE RAIN WITH A FEW EMBEDDED THUNDERSTORMS ARE ALL THAT IS EXPECTED THROUGH THE MID/LATE AFTERNOON...BEFORE THE COLD FRONT PUSHES THROUGH THE REGION. UNDERCUT MAV/MET TEMPERATURES AT MOST LOCATIONS TODAY DUE TO THE EXPECTED CLOUD COVER AND RAIN. A FEW LINGERING SHOWERS ARE POSSIBLE INTO THE EARLY EVENING. OTHERWISE...DRIER AND COOLER CONDITIONS ARE EXPECTED OVER SOUTH FLORIDA TONIGHT. THE WEEKEND LOOKS LIKE IT WILL BE A PLEASANT ONE WITH TEMPERATURES NEAR NORMAL FOR EARLY APRIL. A LIGHT TO MODERATE NORTHEASTERLY FLOW WILL PREVAIL ON SATURDAY...WITH WINDS SHIFTING TO THE EAST ON SUNDAY AS HIGH PRESSURE MOVES INTO THE WESTERN ATLANTIC OFF THE EASTERN CONUS. HIGH PRESSURE WILL REMAIN OVER THE WESTERN ATLANTIC THROUGH THE MIDDLE OF THE WEEK...WITH LOW LEVEL MOISTURE RETURNING TO THE REGION. HIGHS WILL REMAIN IN THE LOW 80S EAST TO THE MID TO UPPER 80S TOWARD THE GULF COAST. OVERNIGHT LOW TEMPERATURES WILL INCREASE TO THE LOWER 70S FOR THE EAST COAST METRO AREAS. A FEW STREAMER SHOWERS WILL BE POSSIBLE EACH DAY FROM TUESDAY THROUGH THE END OF THE WEEK. AVIATION...06Z TAFS. MATURE MCS MOVING ACROSS THE EASTERN GULF AND ACROSS SOUTH FLORIDA EARLY THIS MORNING. STRONG TO SEVERE STORMS ARE POSSIBLE AT KFXE SOUTHWARD ON THE EAST COAST OVER THE NEXT FEW HOURS. PREVAILING MVFR CONDITIONS ARE EXPECTED FOR MOST OF THE EAST COAST TAF SITES THROUGH THE OVERNIGHT HOURS...WITH IFR CONDITIONS POSSIBLE IN THUNDERSTORMS. KAPF IS IN THE RAIN SHIELD ON THE NORTH SIDE OF THE MCS...AND LIGHT/MODERATE RAIN WITH A FEW HIGH BASED LIGHTNING STRIKES WILL CONTINUE THROUGH THE MORNING HOURS. LIGHT/MODERATE RAIN IS EXPECTED AFTER 10-12Z ACROSS THE REGION AS THE MCS MOVES THROUGH AND SOUTH FLORIDA GETS WORKED OVER. AT THIS TIME IS IT DIFFICULT TO SAY WHETHER THERE WILL BE ANY REGENERATION OF THUNDERSTORMS BY THE AFTERNOON HOURS DUE TO ALL THE CLOUD COVER. BASED OFF OF LATEST GUIDANCE...WILL ONLY SHOW RAIN AFTER 12-14Z...WITH CONDITIONS IMPROVING BY MID/LATE AFTERNOON. THE FRONT IS EXPECTED TO PASS THROUGH THE REGION 18-21Z...WITH LIGHT/MODERATE NORTHWESTERLY FLOW THROUGH THE END OF THE TAF PERIOD. MARINE... LATEST GUIDANCE INDICATES THAT WINDS ACROSS THE LOCAL GULF AND ATLANTIC WATERS COULD REACH AROUND 20 KNOTS THIS MORNING AND SEAS ACROSS THE OFF SHORE GULF WATERS COULD REACH NEAR 7 FEET. A SMALL CRAFT ADVISORY IS IN EFFECT THROUGH 00Z THIS EVENING FOR ALL OF THE LOCAL WATERS. A COLD FRONT WILL MOVE THROUGH THE REGION LATE THIS AFTERNOON...WITH WINDS SHIFTING TO THE NORTHWEST BEHIND THE FRONT. NORTHEAST WINDS 15-20 KNOTS ARE EXPECTED ON SATURDAY...WITH EASTERLY WINDS 10-15 KNOTS ON SUNDAY. EAST TO SOUTHEAST WINDS ARE THEN EXPECTED THROUGH THE WEEK AS HIGH PRESSURE BUILDS ACROSS THE WESTERN ATLANTIC. FIRE WEATHER... MUCH NEEDED RAINFALL WILL CONTINUE TO FALL ACROSS MUCH OF THE REGION THROUGH THE DAY TODAY. A FEW EMBEDDED THUNDERSTORMS ARE POSSIBLE INTO THE AFTERNOON. A COLD FRONT WILL MOVE THROUGH THE REGION LATE THIS AFTERNOON INTO THIS EVENING...WITH DRIER AND COOLER CONDITIONS EXPECTED TONIGHT. MINIMUM RELATIVE HUMIDITY VALUES AND SATURDAY ARE EXPECTED TO REMAIN JUST ABOVE CRITICAL VALUES ACROSS THE INTERIOR WEST. HIGH PRESSURE WILL THEN BUILD ACROSS THE WESTERN ATLANTIC SUNDAY THROUGH THE MIDDLE OF THE WEEK...WITH LOW LEVEL MOISTURE RETURNING TO SOUTH FLORIDA. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 79 61 77 67 / 60 10 0 - FORT LAUDERDALE 78 65 79 69 / 70 10 0 - MIAMI 78 64 79 68 / 70 20 0 - NAPLES 75 58 81 62 / 50 10 0 - && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR BISCAYNE BAY-COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL OUT 20 NM-COASTAL WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL OUT 20 NM-LAKE OKEECHOBEE-WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM TO THE TERRITORIAL WATERS OF THE BAHAMAS-WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL EXTENDING FROM 20 NM TO 60 NM. GM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR COASTAL WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM- COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT 20 NM-GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL EXTENDING FROM 20 TO 60 NM. && $$
AREA FORECAST DISCUSSION
NWS MIAMI FL
343 AM EDT FRI APR 5 2013 .DISCUSSION... AN MCS WAS MOVING ACROSS THE EASTERN GULF AND SOUTH FLORIDA EARLY THIS MORNING. AN UPPER LEVEL LOW WAS MOVING EAST ACROSS ALABAMA...WITH BROAD SURFACE LOW PRESSURE AREAS FROM NORTHERN FLORIDA NORTHWARD TO OFF THE COAST OF NORTH CAROLINA. GLOBAL MODELS ARE NOT HANDLING THE CURRENT SITUATION WELL...SO FOLLOWED CLOSER TO THE HRRR OUTPUT THROUGH THE AFTERNOON. THE ATMOSPHERE OVER SOUTH FLORIDA IS EXPECTED TO BECOME WORKED OVER FROM THIS MCS...WITH MUCH MORE STABLE CONDITIONS. CLOUD COVER WILL BLANKET THE REGION FOR MUCH OF THE DAY. SO THE SEVERE THREAT APPEARS TO HAVE DIMINISHED...WITH THE LAST STRONG STORMS ACROSS THE FAR SOUTHEASTERN PORTIONS OF MIAMI DADE COUNTY EARLY THIS MORNING. SO LIGHT/MODERATE RAIN WITH A FEW EMBEDDED THUNDERSTORMS ARE ALL THAT IS EXPECTED THROUGH THE MID/LATE AFTERNOON...BEFORE THE COLD FRONT PUSHES THROUGH THE REGION. UNDERCUT MAV/MET TEMPERATURES AT MOST LOCATIONS TODAY DUE TO THE EXPECTED CLOUD COVER AND RAIN. A FEW LINGERING SHOWERS ARE POSSIBLE INTO THE EARLY EVENING. OTHERWISE...DRIER AND COOLER CONDITIONS ARE EXPECTED OVER SOUTH FLORIDA TONIGHT. THE WEEKEND LOOKS LIKE IT WILL BE A PLEASANT ONE WITH TEMPERATURES NEAR NORMAL FOR EARLY APRIL. A LIGHT TO MODERATE NORTHEASTERLY FLOW WILL PREVAIL ON SATURDAY...WITH WINDS SHIFTING TO THE EAST ON SUNDAY AS HIGH PRESSURE MOVES INTO THE WESTERN ATLANTIC OFF THE EASTERN CONUS. HIGH PRESSURE WILL REMAIN OVER THE WESTERN ATLANTIC THROUGH THE MIDDLE OF THE WEEK...WITH LOW LEVEL MOISTURE RETURNING TO THE REGION. HIGHS WILL REMAIN IN THE LOW 80S EAST TO THE MID TO UPPER 80S TOWARD THE GULF COAST. OVERNIGHT LOW TEMPERATURES WILL INCREASE TO THE LOWER 70S FOR THE EAST COAST METRO AREAS. A FEW STREAMER SHOWERS WILL BE POSSIBLE EACH DAY FROM TUESDAY THROUGH THE END OF THE WEEK. && .AVIATION...06Z TAFS. MATURE MCS MOVING ACROSS THE EASTERN GULF AND ACROSS SOUTH FLORIDA EARLY THIS MORNING. STRONG TO SEVERE STORMS ARE POSSIBLE AT KFXE SOUTHWARD ON THE EAST COAST OVER THE NEXT FEW HOURS. PREVAILING MVFR CONDITIONS ARE EXPECTED FOR MOST OF THE EAST COAST TAF SITES THROUGH THE OVERNIGHT HOURS...WITH IFR CONDITIONS POSSIBLE IN THUNDERSTORMS. KAPF IS IN THE RAIN SHIELD ON THE NORTH SIDE OF THE MCS...AND LIGHT/MODERATE RAIN WITH A FEW HIGH BASED LIGHTNING STRIKES WILL CONTINUE THROUGH THE MORNING HOURS. LIGHT/MODERATE RAIN IS EXPECTED AFTER 10-12Z ACROSS THE REGION AS THE MCS MOVES THROUGH AND SOUTH FLORIDA GETS WORKED OVER. AT THIS TIME IS IT DIFFICULT TO SAY WHETHER THERE WILL BE ANY REGENERATION OF THUNDERSTORMS BY THE AFTERNOON HOURS DUE TO ALL THE CLOUD COVER. BASED OFF OF LATEST GUIDANCE...WILL ONLY SHOW RAIN AFTER 12-14Z...WITH CONDITIONS IMPROVING BY MID/LATE AFTERNOON. THE FRONT IS EXPECTED TO PASS THROUGH THE REGION 18-21Z...WITH LIGHT/MODERATE NORTHWESTERLY FLOW THROUGH THE END OF THE TAF PERIOD. && .MARINE... LATEST GUIDANCE INDICATES THAT WINDS ACROSS THE LOCAL GULF AND ATLANTIC WATERS COULD REACH AROUND 20 KNOTS THIS MORNING AND SEAS ACROSS THE OFF SHORE GULF WATERS COULD REACH NEAR 7 FEET. A SMALL CRAFT ADVISORY IS IN EFFECT THROUGH 00Z THIS EVENING FOR ALL OF THE LOCAL WATERS. A COLD FRONT WILL MOVE THROUGH THE REGION LATE THIS AFTERNOON...WITH WINDS SHIFTING TO THE NORTHWEST BEHIND THE FRONT. NORTHEAST WINDS 15-20 KNOTS ARE EXPECTED ON SATURDAY...WITH EASTERLY WINDS 10-15 KNOTS ON SUNDAY. EAST TO SOUTHEAST WINDS ARE THEN EXPECTED THROUGH THE WEEK AS HIGH PRESSURE BUILDS ACROSS THE WESTERN ATLANTIC. && .FIRE WEATHER... MUCH NEEDED RAINFALL WILL CONTINUE TO FALL ACROSS MUCH OF THE REGION THROUGH THE DAY TODAY. A FEW EMBEDDED THUNDERSTORMS ARE POSSIBLE INTO THE AFTERNOON. A COLD FRONT WILL MOVE THROUGH THE REGION LATE THIS AFTERNOON INTO THIS EVENING...WITH DRIER AND COOLER CONDITIONS EXPECTED TONIGHT. MINIMUM RELATIVE HUMIDITY VALUES AND SATURDAY ARE EXPECTED TO REMAIN JUST ABOVE CRITICAL VALUES ACROSS THE INTERIOR WEST. HIGH PRESSURE WILL THEN BUILD ACROSS THE WESTERN ATLANTIC SUNDAY THROUGH THE MIDDLE OF THE WEEK...WITH LOW LEVEL MOISTURE RETURNING TO SOUTH FLORIDA. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 79 61 77 67 / 60 10 0 - FORT LAUDERDALE 78 65 79 69 / 70 10 0 - MIAMI 78 64 79 68 / 70 20 0 - NAPLES 75 58 81 62 / 50 10 0 - && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR BISCAYNE BAY-COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL OUT 20 NM-COASTAL WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL OUT 20 NM-LAKE OKEECHOBEE-WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM TO THE TERRITORIAL WATERS OF THE BAHAMAS-WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL EXTENDING FROM 20 NM TO 60 NM. GM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR COASTAL WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM- COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT 20 NM-GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL EXTENDING FROM 20 TO 60 NM. && $$ DISCUSSION/MARINE/FIRE...84/AK AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1013 PM CDT SAT APR 6 2013 .DISCUSSION... 912 PM CDT SHOWERS CONTINUE TO MOVE ACROSS NORTHERN ILLINOIS THIS EVENING. HOWEVER...A CLUSTER OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED OVER THE PAST COUPLE HOURS ACROSS EASTERN IOWA. THIS ACTIVITY IS FIRING JUST AHEAD OF A SURFACE COLD FRONT IN AN AREA OF INCREASED ASCENT AHEAD OF A RATHER STOUT MID LEVEL SHORT WAVE...CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING EASTWARD ACROSS SOUTHEASTERN IOWA. THE 00 UTC SOUNDING OUT OF KDVN INDICATES THAT THE AIRMASS IN WHICH THIS ACTIVITY IS DEVELOPING IN POSSES DECENT MID LEVEL LAPSE RATES. HOWEVER...OVERALL INSTABILITY IS RATHER LACK LUSTER...WITH MUCAPE VALUES ONLY UP TO AROUND 100 J/KG. IN SPITE OF THIS...THE STRONGER FORCING FOR ASCENT COMPLEMENTS OF THE MID LEVEL WAVE AND MOISTURE CONVERGENCE IN THE LOWER LEVELS...IS ABLE TO TAKE ADVANTAGE OF THE STEEP LAPSE RATES TO RESULT IN THUNDERSTORMS. THIS ACTIVITY WILL LIKELY MAINTAIN ITSELF FOR THE NEXT FEW HOURS AS IT PUSHES EASTWARD ACROSS NORTHERN ILLINOIS. THERE COULD EVEN BE SOME SMALL HAIL AND SOME GUSTY WINDS IN SOME OF THE STRONGEST STORMS GIVEN THE DRIER AIR IN THE LOWEST FEW THOUSAND FEET. THIS ACTIVITY SHOULD END OVERNIGHT WITH WINDS BECOMING WESTERLY IN THE WAKE OF THE FRONTAL PASSAGE. KJB //PREV DISCUSSION... 259 PM CDT THERE ARE NUMEROUS CHALLENGES WITH THE FORECAST AS THE PATTERN TRANSITIONS TO A MORE ACTIVE ONE...BEGINNING WITH SHOWERS AND SOME SPORADIC THUNDER THIS EVENING AND THEN CARRYING THROUGH THE MIDDLE OF NEXT WEEK. IN ADDITION...THE LIKELY LOCATION OF THE AREA RELATIVE TO SYNOPTIC FEATURES WILL ALLOW FOR TEMPERATURES TO BE HEAVILY DEPENDENT ON CLOUD COVER AND RAIN...ALONG WITH LAKE INDUCED COOLING AT LEAST A FEW OF THE UPCOMING SEVERAL DAYS. NEAR TERM INTO TONIGHT...A FAST PACED BUT MORE AMPLIFIED UPPER LEVEL PATTERN IS ESTABLISHED OVER THE CENTRAL U.S. THIS AFTERNOON WITH A WELL-DEFINED UPPER WAVE ON WATER VAPOR ADVANCING EASTWARD FROM WESTERN IA. A 1000 MB SURFACE LOW REFLECTION ACROSS SOUTHERN MN HAS DEVELOPED AND HELPED TO ESTABLISH STRONG RETURN FLOW WITH WIND GUSTS TO 40 TO 45 MPH AT SEVERAL SITES. THESE WINDS SHOULD DIMINISH GRADUALLY THROUGH THE EVENING HOURS. MOISTURE RETURN HAS STRUGGLED HOWEVER...BOTH AT THE SURFACE AND IN THE DEEP LAYER PER OBSERVATIONS AND PWAT ANALYSIS AND IS A REASON SHOWER COVERAGE IS LIKELY TO BE MORE LIMITED THAN IT COULD BE GIVEN THE UPPER FORCING AHEAD OF THIS WAVE...AND IT WILL TAKE SOME TIME FOR THE VERY DRY LOWER ATMOSPHERE TO SATURATE. A NARROW CORRIDOR OF 700-900 MB MOISTURE TRANSPORT ALONG A MID-LEVEL JET HAS STILL HELPED TO INCREASE ECHOES UPSTREAM DURING THE FIRST HALF OF THE AFTERNOON AND THIS WILL LIKELY BE JUST ENOUGH TO CONTINUE DOING SUCH WITH STEEPENING MID-LEVEL LAPSE RATES IN CONCERT WITH THE NARROW MOISTURE CONVERGENCE. MOST OF THE HIGH-RES CONVECTIVE ALLOWING MODELS PREDICT AN INCREASE IN CONVECTIVE-TYPE ECHOES ACROSS NORTH CENTRAL IL BETWEEN 23Z AND 03Z SHIFTING EASTWARD AND FADING SLOWLY THROUGH EARLY OVERNIGHT AS THE FRONT SHIFTS EAST. WITH SEVERAL OF THESE GUIDANCE MEMBERS INDICATING HIGHER REFLECTIVITY AND A NARROW CORRIDOR OF 200-400 J/KG OF MUCAPE PER THE RAP ALONG THE FRONT...WOULD EXPECT A FEW STORMS WITHIN THE GENERAL SHOWERS. HAVE ADAPTED HOURLY POPS THROUGH THIS EVENING PERIOD OF THE FORECAST. AS PREVIOUS FORECAST DID KEEP MOST OF TONIGHTS TEMPERATURE DROP AFTER THE FRONTAL PASSAGE FROM WEST TO EAST. SUNDAY...HIGH PRESSURE STILL LOOKS TO BRIEFLY PREVAIL FOR THIS PERIOD. THE MOST NOTEWORTHY ASPECT ABOUT THIS IS IT LOOKS TO LINE UP DOWN THE AXIS OF LAKE MICHIGAN BY MIDDAY AND ALLOW FOR A FAIRLY STOUT LAKE BREEZE. THIS WILL BE AIDED BY THE FACT THAT TEMPERATURES SHOULD MODERATE NICELY ON SUNDAY OVER LAND DUE TO ONLY A SMALL WINDOW OF COLD AIR ADVECTION BEHIND THE FRONT TONIGHT AND A DRY AIR MASS AND PREDICTED SUNSHINE DURING SUNDAY. THE TEMPERATURE AND PRESSURE DIFFERENCES WITHIN A LIGHT WIND FIELD SHOULD DRIVE A STRONG LAKE BREEZE...AND THE AFTERNOON TEMPERATURE DROP FOR DOWNTOWN CHICAGO AND OTHER NEAR LAKE AREAS MAY BE AS MUCH AS 15 DEGREES. SUNDAY NIGHT AND MONDAY...AN ACTIVE WEST-TO-EAST PACIFIC JET OVER 120 KT AS SEEN ON HEMISPHERIC WATER VAPOR TODAY WILL DIG ITS WAY INTO THE WESTERN U.S. WITH TROUGH DEVELOPMENT AND UPSTREAM SOUTHWEST FLOW OVER THE MIDWEST. A LEAD IMPULSE IN THIS FLOW IS WELL PREDICTED ON GUIDANCE TO PASS OVER THE AREA DURING LATE SUNDAY NIGHT INTO MONDAY MORNING. THIS LOOKS TO TIGHTEN AN UPPER LEVEL WARM FRONT AND ALLOW FOR SATURATED ISENTROPIC LIFT FOR RAIN SHOWERS. ELEVATED INSTABILITY DOES INCREASE AS THE WARM NOSE BUILDS IN WITHIN THE LOWER LEVELS...AND START THUNDER IN THIS FORECAST PERIOD ITS TOO TOUGH TO DISCERN A PERIOD WHERE THERE WOULD NOT BE A THUNDER CHANCE ALL THE WAY THROUGH WEDNESDAY NIGHT. IN THE WAKE OF THIS LEAD IMPULSE HEIGHTS LOOK TO BUILD ON MONDAY AS THE PRIMARY TROUGH DEVELOPS. ITS A LITTLE INTERESTING AS THERE SHOULD BE A SURFACE WARM FRONT...POSSIBLY DIABATICALLY ENHANCED...LAID OUT SOMEWHERE IN THE CENTRAL IL TO NORTHERN IL REGION. THE ONLY THING IS WITH SHORT WAVE RIDGING HINTED AT THIS FEATURE APPEARS TO BE FAIRLY BENIGN...BUT SOMETHING TO KEEP AN EYE ON. MIDWEEK...AN ACTIVE PERIOD HERE AS PROLONGED SURFACE CYCLOGENESIS BEGINS OVER THE SOUTHERN PLAINS MONDAY NIGHT AND CONTINUES THROUGH TUESDAY WITH THE SURFACE WAVE ADVANCING ENE ON WED. MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THIS...LATCHING MORE ONTO AN EC SOUTHERN SOLUTION. HAVE CONTINUED TO LEAN THAT WAY WITH THE FORECAST WHICH MEANS INHIBITING TEMPERATURES ON WHAT COULD BE GIVEN 850MB TEMPERATURES CLIMBING TO 8C-12C...ESPECIALLY NORTH OF I-80. WITH FLOW OFF THE LAKE TUESDAY AND WEDNESDAY DUE TO THE LOW BEING SOUTHWEST OF THE AREA...TEMPERATURES NEAR THE LAKE WILL REMAIN COOLER. ALSO THIS FORECAST PATTERN MEANS LIKELY SEVERAL BOUTS OF PRECIP WITH THE PROXIMITY OF THE ELEVATED WARM/STATIONARY FRONT. THE 06.12 GFS AND EC RUNS BOTH HAVE OVER TWO AND A HALF INCHES OF RAIN FORECAST AREA WIDE FROM SUNDAY NIGHT THROUGH THURSDAY. WHILE IT IS CHALLENGING TO FOCUS ANY WINDOW FOR CATEGORICAL POPS...IT WOULD SEEM WEDNESDAY AND WEDNESDAY NIGHT WOULD BE THE MOST FAVORED PERIODS FOR STRONGER DYNAMIC FORCING AND POSSIBLY MORE ROBUST ELEVATED CONVECTION WITH THE LARGE SCALE UPPER TROUGH MOVING EASTWARD. COOLING BEHIND THE FRONT LOOKS SOMEWHAT STRONG AND THERE IS A POTENTIAL TO SEE SOME MIX IN THE WAKE OF THE FRONT...BUT CONFIDENCE IS VERY LOW ON HOW THIS SYSTEM WILL EVOLVE AS IT LIFTS OUT. BEYOND...HAVE GONE PRIMARILY WITH A MODEL CONSENSUS AT THE END OF NEXT WEEK AS THE UPPER FLOW PATTERN WORKS FROM BRIEFLY NORTHWEST BACK TO WEST. TEMPERATURES SHOULD GRADUALLY MODERATE BUT CONFIDENCE IS LOW ON PRECIP CHANCES AS THE PATTERN STILL LOOKS DISTURBED. MTF && .FIRE WEATHER... 328 AM...EASTERLY FLOW HAS MAINTAINED MUCH DRIER AIR ACROSS THE REGION AND EXPECT A SLOW RETURN OF LOW LEVEL MOISTURE ACROSS THE AREA TODAY. IT APPEARS DEWPOINTS WILL INCREASE BACK INTO THE 40S...BUT PROBABLY NOT UNTIL LATE AFTERNOON ACROSS WESTERN IL AND THE REST OF THE AREA THIS EVENING. THUS MINIMUM RH VALUES TODAY WILL LIKELY BE IN THE 35-40 PERCENT RANGE AND COULD POSSIBLY DIP INTO THE 30-35 PERCENT RANGE. WHILE THESE EXPECTED VALUES WILL REMAIN ABOVE RED FLAG CRITERIA OF 25 PERCENT...SOUTHERLY WINDS ARE EXPECTED TO QUICKLY INCREASE THIS MORNING WITH GUSTS AS HIGH AS 40 MPH FROM LATE MORNING THROUGH SUNSET WITH THE POTENTIAL FOR HIGHER GUSTS. WHILE THERE COULD BE A FEW LIGHT SHOWERS OR SPRINKLES TODAY...THE BEST TIMING FOR SHOWERS AND A FEW THUNDERSTORMS WILL BE FROM LATE AFTERNOON THROUGH MID/LATE EVENING. TEN HOUR FUEL MOISTURE DIPPED TO 8-9 PERCENT ON FRIDAY AND SIMILAR VALUES ARE POSSIBLE TODAY. AS A RESULT...THERE WILL BE AN INCREASED FIRE DANGER AND WHILE MEETING RED FLAG CRITERIA IS NOT EXPECTED... CONDITIONS WILL NEED TO BE MONITORED THROUGH DAY. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 03Z... * SOUTH-SOUTHWEST WINDS THROUGH THE REST OF THE EVENING SHIFTING WEST- NORTHWEST AFTER 06Z WITH COLD FRONTAL PASSAGE. * FREQUENT WIND GUSTS AROUND 25 KT WITH SPORADIC GUSTS CLOSER TO 30 KT STILL POSSIBLE UNTIL COLD FRONTAL PASSAGE. * ISOLATED SHOWERS/TSRA DEVELOPING NEXT HOUR OR SO WITH BAND OF SHRA/TSRA ARRIVING TOWARD 04Z. SMALL HAIL POSSIBLE. * POTENTIAL FOR LOW END MVFR CIGS OVERNIGHT. * LIGHTER NORTHWEST WINDS SUNDAY WITH LAKE BREEZE TURNING WINDS NORTHEAST THEN EAST LATER SUNDAY AFTERNOON. MDB //DISCUSSION...UPDATED 03Z... COLD FRONT NOW CROSSING THE MISSISSIPPI RIVER WITH A BAND OF SHOWERS AND THUNDERSTORMS STRETCHING FROM KRFD TO KVYS AND POINTS SOUTHWEST. SOME ADDITIONAL ISOLATED ACTIVITY HAS DEVELOPED AHEAD OF THE LINE FROM KDKB TO KPWK WITH THIS SPOTTY ACTIVITY LIKELY CONTINUING TO DEVELOP AHEAD OF THE MAIN BAND. HAVE ADJUSTED THE TAFS TO TIME THE TS ACROSS OVER THE NEXT FEW HOURS. SOME SMALL HAIL MAY OCCUR WITH THE STORMS. OTHERWISE...WIND GUSTS GENERALLY REMAIN IN THE 20 TO 25 KT RANGE WITH SOME SPORADIC/INFREQUENT GUSTS CLOSER TO 30 KT STILL OCCURRING. MAY NEED TO ADJUST TIMING OF THE WIND SHIFT WITH THE FRONT SLIGHTLY. HAVE ALSO LOWERED CIGS TO LOWER END MVFR FOLLOWING THE FRONTAL PASSAGE OVERNIGHT BASED ON SATELLITE TRENDS TO THE WEST. EXPECT THESE CIGS TO SCATTER AROUND OR SOON AFTER DAYBREAK. MDB FROM 00Z... GUSTY SOUTH-SOUTHWEST WINDS CONTINUE...MAINLY FROM CHICAGO LAND EASTWARD AS LOW PRESSURE TRACKS ACROSS WEST-CENTRAL WISCONSIN AND A COLD FRONT MOVES INTO EASTERN IOWA. GUSTS TO AROUND 25 KT CONTINUE WITH SOME INFREQUENT GUSTS TO AROUND 30 KT STILL POPPING UP BUT THE OVERALL TREND APPEARS TO BE DOWNWARD. SHOWER ARE MOVING IN FROM THE WEST AHEAD OF THE FRONT AND THESE MAY ACT TO BRING STRONGER GUSTS BACK AS THEY PASS. SOME THUNDERSTORMS HAVE DEVELOPED JUST AHEAD OF THE FRONT TOWARDS KCID/KIOW AND THIS ACTIVITY MAY EXPAND IN COVERAGE AS IT MOVES EASTWARD. WILL LEAVE TS MENTION OUT OF THE TAFS FOR NOW WITH POTENTIAL TOO LOW TO INCLUDE...30-40 PERCENT...BUT WILL WATCH TRENDS OVER THE NEXT HOUR OR SO AND AMEND TO ADD IF NECESSARY. THE FRONT WILL CROSS THE AREA LATER THIS EVENING AND BRING A SHIFT TO WEST-NORTHWEST WINDS WITH SPEEDS DIMINISHING. THERE IS STILL SOME POTENTIAL FOR LOWERING CIGS BEHIND THE FRONT TONIGHT BUT CONFIDENCE IS LOW. IF THEY DO OCCUR THEN THEY WILL LIKELY BE LOW END MVFR OR POSSIBLY HIGH END IFR FOR A TIME. WILL ALSO MONITOR THIS TREND OVER THE NEXT FEW HOURS AND LOWER TAF CIGS IF NEEDED. RELATIVELY LIGHT NORTHWEST WINDS WILL OCCUR SUNDAY MORNING BUT HIGH PRESSURE WILL MOVE OVERHEAD SO LIGHT AND VARIABLE WINDS MAY PREVAIL BY AFTERNOON. A LAKE BREEZE WILL LIKELY DEVELOP AND TURN WINDS NORTHEASTWARD ACROSS THE CHICAGO AREA TERMINALS DURING THE AFTERNOON. LOW PRESSURE WILL DEVELOP OVER THE CENTRAL HIGH PLAINS LATER SUNDAY ALLOWING A STEADY EAST WIND TO DEVELOP ACROSS ALL AREAS SUNDAY EVENING WHICH WILL TURN SOUTHEASTERLY INTO MONDAY. SHOWER AND THUNDERSTORM CHANCES INCREASE EARLY SUNDAY NIGHT. MDB //ORD AND MDW CONFIDENCE...UPDATED 03Z... * HIGH CONFIDENCE IN WIND DIRECTION TRENDS THROUGH TONIGHT. * MEDIUM-HIGH CONFIDENCE IN FREQUENT GUSTS TO AROUND 25 KT WITH SPORADIC GUSTS TO 30 KT THROUGH LATE EVENING. * HIGH CONFIDENCE IN PRECIP TIMING/DURATION. * MEDIUM CONFIDENCE IN LOW MVFR CIG POTENTIAL OVERNIGHT. * HIGH CONFIDENCE IN WIND TRENDS/LAKE BREEZE SUNDAY. MDB //OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z... MONDAY...SHRA/TSRA LIKELY EARLY. MVFR/BRIEF IFR POSSIBLE EARLY. TUESDAY THROUGH THURSDAY NIGHT...PERIODIC CHANCE FOR SHRA/TSRA. PERIODIC MVFR CIGS/VSBY LIKELY WITH BRIEF IFR POSSIBLE. FRIDAY...PROBABLE VFR. MDB && .MARINE... 241 PM CDT LOW PRESSURE OVER SOUTHERN MINNESOTA THIS AFTERNOON IS LIFTING A STRONG WARM FRONT ACROSS LAKE MICHIGAN TODAY. WINDS OVER THE LAND ARE TOPPING OUT AROUND 35 KT THIS AFTERNOON WITH THESE GALES EXTENDING INTO THE NEARSHORE WATERS WHERE A GALE WARNING REMAINS IN EFFECT THROUGH THIS EVENING. HOWEVER...WITH TEMPERATURES PUSHING 70 ACROSS NORTHERN ILLINOIS/INDIANA...VERY STABLE CONDITIONS ARE SETTING UP OVER THE OPEN WATERS OF THE LAKE AND SHOULD BE INHIBITING THE STRONGER GUSTS FROM REACHING THE LAKE SURFACE. THE LOW WILL MOVE ACROSS NORTHERN LAKE MICHIGAN LATE THIS EVENING WITH A TRAILING COLD FRONT PUSHING ACROSS THE LAKE SHORTLY THEREAFTER WITH WINDS TURNING WESTERLY AND DIMINISHING. ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO MOVE INTO THE REGION MIDWEEK...THOUGH MODELS CONTINUE TO STRUGGLE WITH TRACK AND TIMING MAKING IT DIFFICULT TO PIN DOWN DETAILS REGARDING OVER THE LAKE. CONTINUE TO FAVOR A FARTHER SOUTH SOLUTION SUPPORTED BY THE CONSISTENT ECMWF...WHICH THE LATEST GFS HAS TRENDED TOWARDS. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 AM SUNDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
915 PM CDT SAT APR 6 2013 .DISCUSSION... 912 PM CDT SHOWERS CONTINUE TO MOVE ACROSS NORTHERN ILLINOIS THIS EVENING. HOWEVER...A CLUSTER OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED OVER THE PAST COUPLE HOURS ACROSS EASTERN IOWA. THIS ACTIVITY IS FIRING JUST AHEAD OF A SURFACE COLD FRONT IN AN AREA OF INCREASED ASCENT AHEAD OF A RATHER STOUT MID LEVEL SHORT WAVE...CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING EASTWARD ACROSS SOUTHEASTERN IOWA. THE 00 UTC SOUNDING OUT OF KDVN INDICATES THAT THE AIRMASS IN WHICH THIS ACTIVITY IS DEVELOPING IN POSSES DECENT MID LEVEL LAPSE RATES. HOWEVER...OVERALL INSTABILITY IS RATHER LACK LUSTER...WITH MUCAPE VALUES ONLY UP TO AROUND 100 J/KG. IN SPITE OF THIS...THE STRONGER FORCING FOR ASCENT COMPLEMENTS OF THE MID LEVEL WAVE AND MOISTURE CONVERGENCE IN THE LOWER LEVELS...IS ABLE TO TAKE ADVANTAGE OF THE STEEP LAPSE RATES TO RESULT IN THUNDERSTORMS. THIS ACTIVITY WILL LIKELY MAINTAIN ITSELF FOR THE NEXT FEW HOURS AS IT PUSHES EASTWARD ACROSS NORTHERN ILLINOIS. THERE COULD EVEN BE SOME SMALL HAIL AND SOME GUSTY WINDS IN SOME OF THE STRONGEST STORMS GIVEN THE DRIER AIR IN THE LOWEST FEW THOUSAND FEET. THIS ACTIVITY SHOULD END OVERNIGHT WITH WINDS BECOMING WESTERLY IN THE WAKE OF THE FRONTAL PASSAGE. KJB && .PREV DISCUSSION... 259 PM CDT THERE ARE NUMEROUS CHALLENGES WITH THE FORECAST AS THE PATTERN TRANSITIONS TO A MORE ACTIVE ONE...BEGINNING WITH SHOWERS AND SOME SPORADIC THUNDER THIS EVENING AND THEN CARRYING THROUGH THE MIDDLE OF NEXT WEEK. IN ADDITION...THE LIKELY LOCATION OF THE AREA RELATIVE TO SYNOPTIC FEATURES WILL ALLOW FOR TEMPERATURES TO BE HEAVILY DEPENDENT ON CLOUD COVER AND RAIN...ALONG WITH LAKE INDUCED COOLING AT LEAST A FEW OF THE UPCOMING SEVERAL DAYS. NEAR TERM INTO TONIGHT...A FAST PACED BUT MORE AMPLIFIED UPPER LEVEL PATTERN IS ESTABLISHED OVER THE CENTRAL U.S. THIS AFTERNOON WITH A WELL-DEFINED UPPER WAVE ON WATER VAPOR ADVANCING EASTWARD FROM WESTERN IA. A 1000 MB SURFACE LOW REFLECTION ACROSS SOUTHERN MN HAS DEVELOPED AND HELPED TO ESTABLISH STRONG RETURN FLOW WITH WIND GUSTS TO 40 TO 45 MPH AT SEVERAL SITES. THESE WINDS SHOULD DIMINISH GRADUALLY THROUGH THE EVENING HOURS. MOISTURE RETURN HAS STRUGGLED HOWEVER...BOTH AT THE SURFACE AND IN THE DEEP LAYER PER OBSERVATIONS AND PWAT ANALYSIS AND IS A REASON SHOWER COVERAGE IS LIKELY TO BE MORE LIMITED THAN IT COULD BE GIVEN THE UPPER FORCING AHEAD OF THIS WAVE...AND IT WILL TAKE SOME TIME FOR THE VERY DRY LOWER ATMOSPHERE TO SATURATE. A NARROW CORRIDOR OF 700-900 MB MOISTURE TRANSPORT ALONG A MID-LEVEL JET HAS STILL HELPED TO INCREASE ECHOES UPSTREAM DURING THE FIRST HALF OF THE AFTERNOON AND THIS WILL LIKELY BE JUST ENOUGH TO CONTINUE DOING SUCH WITH STEEPENING MID-LEVEL LAPSE RATES IN CONCERT WITH THE NARROW MOISTURE CONVERGENCE. MOST OF THE HIGH-RES CONVECTIVE ALLOWING MODELS PREDICT AN INCREASE IN CONVECTIVE-TYPE ECHOES ACROSS NORTH CENTRAL IL BETWEEN 23Z AND 03Z SHIFTING EASTWARD AND FADING SLOWLY THROUGH EARLY OVERNIGHT AS THE FRONT SHIFTS EAST. WITH SEVERAL OF THESE GUIDANCE MEMBERS INDICATING HIGHER REFLECTIVITY AND A NARROW CORRIDOR OF 200-400 J/KG OF MUCAPE PER THE RAP ALONG THE FRONT...WOULD EXPECT A FEW STORMS WITHIN THE GENERAL SHOWERS. HAVE ADAPTED HOURLY POPS THROUGH THIS EVENING PERIOD OF THE FORECAST. AS PREVIOUS FORECAST DID KEEP MOST OF TONIGHTS TEMPERATURE DROP AFTER THE FRONTAL PASSAGE FROM WEST TO EAST. SUNDAY...HIGH PRESSURE STILL LOOKS TO BRIEFLY PREVAIL FOR THIS PERIOD. THE MOST NOTEWORTHY ASPECT ABOUT THIS IS IT LOOKS TO LINE UP DOWN THE AXIS OF LAKE MICHIGAN BY MIDDAY AND ALLOW FOR A FAIRLY STOUT LAKE BREEZE. THIS WILL BE AIDED BY THE FACT THAT TEMPERATURES SHOULD MODERATE NICELY ON SUNDAY OVER LAND DUE TO ONLY A SMALL WINDOW OF COLD AIR ADVECTION BEHIND THE FRONT TONIGHT AND A DRY AIR MASS AND PREDICTED SUNSHINE DURING SUNDAY. THE TEMPERATURE AND PRESSURE DIFFERENCES WITHIN A LIGHT WIND FIELD SHOULD DRIVE A STRONG LAKE BREEZE...AND THE AFTERNOON TEMPERATURE DROP FOR DOWNTOWN CHICAGO AND OTHER NEAR LAKE AREAS MAY BE AS MUCH AS 15 DEGREES. SUNDAY NIGHT AND MONDAY...AN ACTIVE WEST-TO-EAST PACIFIC JET OVER 120 KT AS SEEN ON HEMISPHERIC WATER VAPOR TODAY WILL DIG ITS WAY INTO THE WESTERN U.S. WITH TROUGH DEVELOPMENT AND UPSTREAM SOUTHWEST FLOW OVER THE MIDWEST. A LEAD IMPULSE IN THIS FLOW IS WELL PREDICTED ON GUIDANCE TO PASS OVER THE AREA DURING LATE SUNDAY NIGHT INTO MONDAY MORNING. THIS LOOKS TO TIGHTEN AN UPPER LEVEL WARM FRONT AND ALLOW FOR SATURATED ISENTROPIC LIFT FOR RAIN SHOWERS. ELEVATED INSTABILITY DOES INCREASE AS THE WARM NOSE BUILDS IN WITHIN THE LOWER LEVELS...AND START THUNDER IN THIS FORECAST PERIOD ITS TOO TOUGH TO DISCERN A PERIOD WHERE THERE WOULD NOT BE A THUNDER CHANCE ALL THE WAY THROUGH WEDNESDAY NIGHT. IN THE WAKE OF THIS LEAD IMPULSE HEIGHTS LOOK TO BUILD ON MONDAY AS THE PRIMARY TROUGH DEVELOPS. ITS A LITTLE INTERESTING AS THERE SHOULD BE A SURFACE WARM FRONT...POSSIBLY DIABATICALLY ENHANCED...LAID OUT SOMEWHERE IN THE CENTRAL IL TO NORTHERN IL REGION. THE ONLY THING IS WITH SHORT WAVE RIDGING HINTED AT THIS FEATURE APPEARS TO BE FAIRLY BENIGN...BUT SOMETHING TO KEEP AN EYE ON. MIDWEEK...AN ACTIVE PERIOD HERE AS PROLONGED SURFACE CYCLOGENESIS BEGINS OVER THE SOUTHERN PLAINS MONDAY NIGHT AND CONTINUES THROUGH TUESDAY WITH THE SURFACE WAVE ADVANCING ENE ON WED. MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THIS...LATCHING MORE ONTO AN EC SOUTHERN SOLUTION. HAVE CONTINUED TO LEAN THAT WAY WITH THE FORECAST WHICH MEANS INHIBITING TEMPERATURES ON WHAT COULD BE GIVEN 850MB TEMPERATURES CLIMBING TO 8C-12C...ESPECIALLY NORTH OF I-80. WITH FLOW OFF THE LAKE TUESDAY AND WEDNESDAY DUE TO THE LOW BEING SOUTHWEST OF THE AREA...TEMPERATURES NEAR THE LAKE WILL REMAIN COOLER. ALSO THIS FORECAST PATTERN MEANS LIKELY SEVERAL BOUTS OF PRECIP WITH THE PROXIMITY OF THE ELEVATED WARM/STATIONARY FRONT. THE 06.12 GFS AND EC RUNS BOTH HAVE OVER TWO AND A HALF INCHES OF RAIN FORECAST AREA WIDE FROM SUNDAY NIGHT THROUGH THURSDAY. WHILE IT IS CHALLENGING TO FOCUS ANY WINDOW FOR CATEGORICAL POPS...IT WOULD SEEM WEDNESDAY AND WEDNESDAY NIGHT WOULD BE THE MOST FAVORED PERIODS FOR STRONGER DYNAMIC FORCING AND POSSIBLY MORE ROBUST ELEVATED CONVECTION WITH THE LARGE SCALE UPPER TROUGH MOVING EASTWARD. COOLING BEHIND THE FRONT LOOKS SOMEWHAT STRONG AND THERE IS A POTENTIAL TO SEE SOME MIX IN THE WAKE OF THE FRONT...BUT CONFIDENCE IS VERY LOW ON HOW THIS SYSTEM WILL EVOLVE AS IT LIFTS OUT. BEYOND...HAVE GONE PRIMARILY WITH A MODEL CONSENSUS AT THE END OF NEXT WEEK AS THE UPPER FLOW PATTERN WORKS FROM BRIEFLY NORTHWEST BACK TO WEST. TEMPERATURES SHOULD GRADUALLY MODERATE BUT CONFIDENCE IS LOW ON PRECIP CHANCES AS THE PATTERN STILL LOOKS DISTURBED. MTF && .FIRE WEATHER... 328 AM...EASTERLY FLOW HAS MAINTAINED MUCH DRIER AIR ACROSS THE REGION AND EXPECT A SLOW RETURN OF LOW LEVEL MOISTURE ACROSS THE AREA TODAY. IT APPEARS DEWPOINTS WILL INCREASE BACK INTO THE 40S...BUT PROBABLY NOT UNTIL LATE AFTERNOON ACROSS WESTERN IL AND THE REST OF THE AREA THIS EVENING. THUS MINIMUM RH VALUES TODAY WILL LIKELY BE IN THE 35-40 PERCENT RANGE AND COULD POSSIBLY DIP INTO THE 30-35 PERCENT RANGE. WHILE THESE EXPECTED VALUES WILL REMAIN ABOVE RED FLAG CRITERIA OF 25 PERCENT...SOUTHERLY WINDS ARE EXPECTED TO QUICKLY INCREASE THIS MORNING WITH GUSTS AS HIGH AS 40 MPH FROM LATE MORNING THROUGH SUNSET WITH THE POTENTIAL FOR HIGHER GUSTS. WHILE THERE COULD BE A FEW LIGHT SHOWERS OR SPRINKLES TODAY...THE BEST TIMING FOR SHOWERS AND A FEW THUNDERSTORMS WILL BE FROM LATE AFTERNOON THROUGH MID/LATE EVENING. TEN HOUR FUEL MOISTURE DIPPED TO 8-9 PERCENT ON FRIDAY AND SIMILAR VALUES ARE POSSIBLE TODAY. AS A RESULT...THERE WILL BE AN INCREASED FIRE DANGER AND WHILE MEETING RED FLAG CRITERIA IS NOT EXPECTED... CONDITIONS WILL NEED TO BE MONITORED THROUGH DAY. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 00Z... * 180-210 DEGREE WINDS THROUGH MID EVENING WITH SOME VARIABILITY TO 220-230 AFTER APPROX 03Z. WINDS SHIFT WEST-NORTHWEST AFTER 06Z WITH COLD FRONTAL PASSAGE. * FREQUENT WIND GUSTS AROUND 25 KT WITH SPORADIC GUSTS CLOSER TO 30 KT MAINLY THROUGH SUNSET...APPROACHING SHOWERS MAY PRODUCE 30 KT GUSTS THROUGH THE EVENING. * STEADIER RAIN SHOWERS ARRIVING TOWARD 01Z WITH A CHANCE FOR SHORT PERIOD OF TS AFTER ABOUT 03Z. * POTENTIAL FOR LOW END MVFR CIGS OVERNIGHT. * LIGHTER NORTHWEST WINDS SUNDAY WITH LAKE BREEZE TURNING WINDS NORTHEAST THEN EAST LATER SUNDAY AFTERNOON. MDB //DISCUSSION...UPDATED 00Z... GUSTY SOUTH-SOUTHWEST WINDS CONTINUE...MAINLY FROM CHICAGO LAND EASTWARD AS LOW PRESSURE TRACKS ACROSS WEST-CENTRAL WISCONSIN AND A COLD FRONT MOVES INTO EASTERN IOWA. GUSTS TO AROUND 25 KT CONTINUE WITH SOME INFREQUENT GUSTS TO AROUND 30 KT STILL POPPING UP BUT THE OVERALL TREND APPEARS TO BE DOWNWARD. SHOWER ARE MOVING IN FROM THE WEST AHEAD OF THE FRONT AND THESE MAY ACT TO BRING STRONGER GUSTS BACK AS THEY PASS. SOME THUNDERSTORMS HAVE DEVELOPED JUST AHEAD OF THE FRONT TOWARDS KCID/KIOW AND THIS ACTIVITY MAY EXPAND IN COVERAGE AS IT MOVES EASTWARD. WILL LEAVE TS MENTION OUT OF THE TAFS FOR NOW WITH POTENTIAL TOO LOW TO INCLUDE...30-40 PERCENT...BUT WILL WATCH TRENDS OVER THE NEXT HOUR OR SO AND AMEND TO ADD IF NECESSARY. THE FRONT WILL CROSS THE AREA LATER THIS EVENING AND BRING A SHIFT TO WEST-NORTHWEST WINDS WITH SPEEDS DIMINISHING. THERE IS STILL SOME POTENTIAL FOR LOWERING CIGS BEHIND THE FRONT TONIGHT BUT CONFIDENCE IS LOW. IF THEY DO OCCUR THEN THEY WILL LIKELY BE LOW END MVFR OR POSSIBLY HIGH END IFR FOR A TIME. WILL ALSO MONITOR THIS TREND OVER THE NEXT FEW HOURS AND LOWER TAF CIGS IF NEEDED. RELATIVELY LIGHT NORTHWEST WINDS WILL OCCUR SUNDAY MORNING BUT HIGH PRESSURE WILL MOVE OVERHEAD SO LIGHT AND VARIABLE WINDS MAY PREVAIL BY AFTERNOON. A LAKE BREEZE WILL LIKELY DEVELOP AND TURN WINDS NORTHEASTWARD ACROSS THE CHICAGO AREA TERMINALS DURING THE AFTERNOON. LOW PRESSURE WILL DEVELOP OVER THE CENTRAL HIGH PLAINS LATER SUNDAY ALLOWING A STEADY EAST WIND TO DEVELOP ACROSS ALL AREAS SUNDAY EVENING WHICH WILL TURN SOUTHEASTERLY INTO MONDAY. SHOWER AND THUNDERSTORM CHANCES INCREASE EARLY SUNDAY NIGHT. MDB //ORD AND MDW CONFIDENCE...UPDATED 00Z... * HIGH CONFIDENCE IN WIND DIRECTION TRENDS THROUGH TONIGHT. * MEDIUM-HIGH CONFIDENCE IN FREQUENT GUSTS TO AROUND 25 KT WITH SPORADIC GUSTS TO 30 KT THROUGH SUNSET. * HIGH CONFIDENCE IN PRECIP TIMING/DURATION...MEDIUM CONFIDENCE IN TS POTENTIAL AND TIMING BUT CHANCE IS TOO LOW TO MENTION IN TAF RIGHT NOW. * LOW CONFIDENCE IN LOW MVFR CIG POTENTIAL OVERNIGHT. * HIGH CONFIDENCE IN WIND TRENDS/LAKE BREEZE SUNDAY. MDB //OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z... MONDAY...SHRA/TSRA LIKELY EARLY. MVFR/BRIEF IFR POSSIBLE EARLY. TUESDAY THROUGH THURSDAY NIGHT...PERIODIC CHANCE FOR SHRA/TSRA. PERIODIC MVFR CIGS/VSBY LIKELY WITH BRIEF IFR POSSIBLE. FRIDAY...PROBABLE VFR. MDB && .MARINE... 241 PM CDT LOW PRESSURE OVER SOUTHERN MINNESOTA THIS AFTERNOON IS LIFTING A STRONG WARM FRONT ACROSS LAKE MICHIGAN TODAY. WINDS OVER THE LAND ARE TOPPING OUT AROUND 35 KT THIS AFTERNOON WITH THESE GALES EXTENDING INTO THE NEARSHORE WATERS WHERE A GALE WARNING REMAINS IN EFFECT THROUGH THIS EVENING. HOWEVER...WITH TEMPERATURES PUSHING 70 ACROSS NORTHERN ILLINOIS/INDIANA...VERY STABLE CONDITIONS ARE SETTING UP OVER THE OPEN WATERS OF THE LAKE AND SHOULD BE INHIBITING THE STRONGER GUSTS FROM REACHING THE LAKE SURFACE. THE LOW WILL MOVE ACROSS NORTHERN LAKE MICHIGAN LATE THIS EVENING WITH A TRAILING COLD FRONT PUSHING ACROSS THE LAKE SHORTLY THEREAFTER WITH WINDS TURNING WESTERLY AND DIMINISHING. ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO MOVE INTO THE REGION MIDWEEK...THOUGH MODELS CONTINUE TO STRUGGLE WITH TRACK AND TIMING MAKING IT DIFFICULT TO PIN DOWN DETAILS REGARDING OVER THE LAKE. CONTINUE TO FAVOR A FARTHER SOUTH SOLUTION SUPPORTED BY THE CONSISTENT ECMWF...WHICH THE LATEST GFS HAS TRENDED TOWARDS. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...NEARSHORE WATERS UNTIL 10 PM SATURDAY. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
909 PM CDT SAT APR 6 2013 .DISCUSSION... ISSUED 900 PM CDT SAT APR 6 2013 A LINE OF SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE TO PROGRESS EASTWARD ACROSS THE NORTHERN HALF OF THE CWA THIS EVENING AHEAD OF A COLD FRONT. THE WINDOW OF OPPORTUNITY FOR THUNDER LOOKS TO BE AROUND 2 HOURS WITH THUNDER JUST REPORTED IN PIA AHEAD OF THE STRONGER LINE BACK NEAR GALESBURG. THE LOW LEVEL CONVERGENCE AND INSTABILITY LOOKS TO BE GRADUALLY WEAKENING AFTER SUNSET...AND THE FRONTAL CIRCULATIONS ARE FORECAST TO NEARLY DISSIPATE BY 12Z WHEN THE FRONT REACHES OUR SOUTHEAST COUNTIES. WE MAINLY KEPT THE HIGH CHANCE POPS ACROSS THE NORTH...AND PROGRESSED THEM TOWARD CHAMPAIGN BY 06Z/1AM WITH ONLY SLIGHT CHANCE POPS IN THE SOUTHEAST THIRD OF OUR COUNTIES AFTER 06Z/1AM. THE GUSTY WINDS ARE MAINLY CONFINED TO AREAS EAST OF LINCOLN TO BLOOMINGTON AT 9 PM. LIGHTER WINDS WILL ARRIVE WITH THE COLD FRONT AND A WIND SHIFT TO THE WEST. THE FRONT IS STILL EXPECTED TO RETURN NORTH AND BECOME ACTIVE AGAIN SUNDAY AFTERNOON AND ESPECIALLY SUNDAY NIGHT IN THE WEST. FOR TONIGHT...UPDATED THE POP/WEATHER AND WINDS TO MORE CLOSELY MATCH CURRENT TRENDS. NO MAJOR CHANCES OVERALL. UPDATED INFO WILL BE AVAILABLE SHORTLY. SHIMON && .AVIATION... ISSUED 700 PM CDT SAT APR 6 2013...FOR THE 00Z TAFS A COLD FRONT MOVING ACROSS CENTRAL ILLINOIS THIS EVENING SHOULD HAVE ENOUGH INSTABILITY FOR AT LEAST A LINE OF SHOWERS AND ISOLATED THUNDERSTORMS TO DEVELOP DURING A MOVING 2 TO 4 HOUR WINDOW THIS EVENING. THE PRECIP SHOULD DEVELOP IN PIA SHORTLY BETWEEN 00-01Z AND ADVANCE EASTWARD FROM THERE, REACHING CMI BY 04Z. THE HRRR MODEL OUTPUT SEEMS TO HAVE A GOOD HANDLE ON THE CURRENT STATUS OF THE SYSTEM...AND GENERALLY FOLLOWED ITS OUTPUT ON TIMING. I DECIDED TO LEAVE OUT THUNDER IN THE TAFS DUE TO THE ISOLATED NATURE AND LOW CONFIDENCE THAT ANY STORM WILL COME WITHIN 5 MILES OF ANY TERMINAL SITE. VERY GUSTY WINDS WILL DIMINISH SOME THIS EVENING...BUT A FEW GUSTS IN THE 25-28KT RANGE WILL CONTINUE FOR AT LEAST A COUPLE HOURS BEFORE THE FRONT ARRIVES FROM WEST TO EAST. WINDS WILL SHIFT TO THE WEST BEHIND THE FRONT...AND BECOME MUCH LIGHTER...AROUND 12-13KT. EVEN LIGHTER SOUTHWEST WINDS ARE EXPECTED TOMORROW UNDER ADVANCING HIGH PRESSURE. SHIMON && .PREV DISCUSSION... ISSUED 300 PM CDT SAT APR 6 2013 00Z MODELS CONTINUE A MILD AND UNSETTLED WEATHER PATTERN THROUGH MID WEEK WITH COOLER AND DRIER CONDITIONS THE END OF NEXT WEEK. WILL USE A MODEL BLEND THIS FORECAST PACKAGE. MET AND MAV GUIDANCE TEMPS ARE SIMILAR THROUGH MON NIGHT AND STAYED FAIRLY CLOSE TO. SHORT TERM...TODAY THROUGH TUESDAY NIGHT STRONG SOUTH WINDS OF 20-35 MPH AND GUSTS OF 35-50 MPH THIS AFTERNOON WITH STRONGEST WIND GUSTS FROM I-72 NORTH. A SPECIAL WEATHER STATEMENT WAS ISSUED TO ADDRESS THESE HIGH WINDS THROUGH 8 PM. 999 MB LOW PRESSURE OVER SOUTHCENTRAL MN HAS A COLD FRONT INTO CENTRAL IA...NW MO AND CENTRAL OK. WARM FRONT HAD LIFTED NE OF IL WITH MILD TEMPS IN THE UPPER 60S AND LOWER 70S OVER CENTRAL AND SE IL AND MILDEST TEMPS SINCE NOV 10TH. LOW PRESSURE TO MOVE TOWARD NORTHERN LAKE MI BY 06Z TONIGHT AND PULL COLD FRONT TOWARD I-55. LOW PRESSURE DEEPENS TO 996 MB JUST EAST OF UPPER MI BY 12Z/SUN AND COLD FRONT SWEEPS THROUGH SE IL LATE TONIGHT INTO MID MORNING SUNDAY. HAVE CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS OVER CENTRAL IL THIS EVENING AND SHIFTING INTO SE IL OVERNIGHT INTO MID MORNING SUNDAY. LIMITED MOISTURE WITH COLD FRONT AND MODELS HAVE TRENDED LOWER WITH QPF AMOUNTS TONIGHT INTO SUNDAY. LOWS TONIGHT RANGE FROM THE LOWER 40S NW OF THE IL RIVER TO THE LOWER 50S IN SE IL. FRONTAL BOUNDARY TO START LIFTING BACK NORTH TOWARD CENTRAL/SE IL BY SUNSET SUNDAY AND RETURNING 20-40% CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS LATE SUNDAY AFTERNOON INTO PARTS OF CENTRAL AND SW IL. HIGHS TO RANGE FROM THE MID 60S NORTH OF PEORIA TO THE LOWER 70S SOUTH OF I-72. WARM FRONT LIFTS NORTH THROUGH CENTRAL IL SUNDAY NIGHT AND INTO NORTHERN IL MON AND LIKELY ACCOMPANIED BY A SHOWERS AND A CHANCE OF THUNDERSTORMS ESPECIALLY NORTH OF I-70. MILD HIGHS MON AGAIN IN THE UPPER 60S AND LOWER 70S WITH COOLEST READINGS FROM I-74 NORTH. CHANCES OF SHOWERS AND THUNDERSTORMS LINGERS TUE AND HIGHEST POPS IN NORTHERN AREAS CLOSER TO FRONTAL BOUNDARY LINGERING OVER NORTHERN IL. LONG TERM...WEDNESDAY THROUGH SATURDAY STRONG LOW PRESSURE TO EJECT NE AROUND WED WITH BEST CHANCES OF SHOWERS AND THUNDERSTORMS AND SPC HAS RISK OF STRONG TO SEVERE STORMS OVER SOUTHERN IL WED. GFS IS QUICKER WITH THIS STORM SYSTEM THAN THE ECMWF MODEL AND USED A BLEND FOR NOW WITH PLENTY OF TIME TO SORT OUT THE TIMING DIFFERENCES. MAY BE A GRADIENT OF TEMPS WED WITH COOLER HIGHS IN THE UPPER 50S NW OF THE IL RIVER AND MILDER LOWER 70S SE OF I-70. STRONG UPPER LEVEL TROF OVER THE MIDWEST THU TO KEEP LOW CLOUDS AROUND ALONG WITH LINGERING CHANCES OF SHOWERS AND COOLER TEMPS. DRIER WEATHER EXPECTED FRIDAY ALONG WITH TEMPS BEING A BIT COOLER THAN NORMAL THU/FRI WITH HIGHS IN THE 50S. 07 && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
702 PM CDT SAT APR 6 2013 .DISCUSSION... ISSUED 300 PM CDT SAT APR 6 2013 00Z MODELS CONTINUE A MILD AND UNSETTLED WEATHER PATTERN THROUGH MID WEEK WITH COOLER AND DRIER CONDITIONS THE END OF NEXT WEEK. WILL USE A MODEL BLEND THIS FORECAST PACKAGE. MET AND MAV GUIDANCE TEMPS ARE SIMILAR THROUGH MON NIGHT AND STAYED FAIRLY CLOSE TO. SHORT TERM...TODAY THROUGH TUESDAY NIGHT STRONG SOUTH WINDS OF 20-35 MPH AND GUSTS OF 35-50 MPH THIS AFTERNOON WITH STRONGEST WIND GUSTS FROM I-72 NORTH. A SPECIAL WEATHER STATEMENT WAS ISSUED TO ADDRESS THESE HIGH WINDS THROUGH 8 PM. 999 MB LOW PRESSURE OVER SOUTHCENTRAL MN HAS A COLD FRONT INTO CENTRAL IA...NW MO AND CENTRAL OK. WARM FRONT HAD LIFTED NE OF IL WITH MILD TEMPS IN THE UPPER 60S AND LOWER 70S OVER CENTRAL AND SE IL AND MILDEST TEMPS SINCE NOV 10TH. LOW PRESSURE TO MOVE TOWARD NORTHERN LAKE MI BY 06Z TONIGHT AND PULL COLD FRONT TOWARD I-55. LOW PRESSURE DEEPENS TO 996 MB JUST EAST OF UPPER MI BY 12Z/SUN AND COLD FRONT SWEEPS THROUGH SE IL LATE TONIGHT INTO MID MORNING SUNDAY. HAVE CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS OVER CENTRAL IL THIS EVENING AND SHIFTING INTO SE IL OVERNIGHT INTO MID MORNING SUNDAY. LIMITED MOISTURE WITH COLD FRONT AND MODELS HAVE TRENDED LOWER WITH QPF AMOUNTS TONIGHT INTO SUNDAY. LOWS TONIGHT RANGE FROM THE LOWER 40S NW OF THE IL RIVER TO THE LOWER 50S IN SE IL. FRONTAL BOUNDARY TO START LIFTING BACK NORTH TOWARD CENTRAL/SE IL BY SUNSET SUNDAY AND RETURNING 20-40% CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS LATE SUNDAY AFTERNOON INTO PARTS OF CENTRAL AND SW IL. HIGHS TO RANGE FROM THE MID 60S NORTH OF PEORIA TO THE LOWER 70S SOUTH OF I-72. WARM FRONT LIFTS NORTH THROUGH CENTRAL IL SUNDAY NIGHT AND INTO NORTHERN IL MON AND LIKELY ACCOMPANIED BY A SHOWERS AND A CHANCE OF THUNDERSTORMS ESPECIALLY NORTH OF I-70. MILD HIGHS MON AGAIN IN THE UPPER 60S AND LOWER 70S WITH COOLEST READINGS FROM I-74 NORTH. CHANCES OF SHOWERS AND THUNDERSTORMS LINGERS TUE AND HIGHEST POPS IN NORTHERN AREAS CLOSER TO FRONTAL BOUNDARY LINGERING OVER NORTHERN IL. LONG TERM...WEDNESDAY THROUGH SATURDAY STRONG LOW PRESSURE TO EJECT NE AROUND WED WITH BEST CHANCES OF SHOWERS AND THUNDERSTORMS AND SPC HAS RISK OF STRONG TO SEVERE STORMS OVER SOUTHERN IL WED. GFS IS QUICKER WITH THIS STORM SYSTEM THAN THE ECMWF MODEL AND USED A BLEND FOR NOW WITH PLENTY OF TIME TO SORT OUT THE TIMING DIFFERENCES. MAY BE A GRADIENT OF TEMPS WED WITH COOLER HIGHS IN THE UPPER 50S NW OF THE IL RIVER AND MILDER LOWER 70S SE OF I-70. STRONG UPPER LEVEL TROF OVER THE MIDWEST THU TO KEEP LOW CLOUDS AROUND ALONG WITH LINGERING CHANCES OF SHOWERS AND COOLER TEMPS. DRIER WEATHER EXPECTED FRIDAY ALONG WITH TEMPS BEING A BIT COOLER THAN NORMAL THU/FRI WITH HIGHS IN THE 50S. 07 && .AVIATION... ISSUED 700 PM CDT SAT APR 6 2013...FOR THE 00Z TAFS A COLD FRONT MOVING ACROSS CENTRAL ILLINOIS THIS EVENING SHOULD HAVE ENOUGH INSTABILITY FOR AT LEAST A LINE OF SHOWERS AND ISOLATED THUNDERSTORMS TO DEVELOP DURING A MOVING 2 TO 4 HOUR WINDOW THIS EVENING. THE PRECIP SHOULD DEVELOP IN PIA SHORTLY BETWEEN 00-01Z AND ADVANCE EASTWARD FROM THERE, REACHING CMI BY 04Z. THE HRRR MODEL OUTPUT SEEMS TO HAVE A GOOD HANDLE ON THE CURRENT STATUS OF THE SYSTEM...AND GENERALLY FOLLOWED ITS OUTPUT ON TIMING. I DECIDED TO LEAVE OUT THUNDER IN THE TAFS DUE TO THE ISOLATED NATURE AND LOW CONFIDENCE THAT ANY STORM WILL COME WITHIN 5 MILES OF ANY TERMINAL SITE. VERY GUSTY WINDS WILL DIMINISH SOME THIS EVENING...BUT A FEW GUSTS IN THE 25-28KT RANGE WILL CONTINUE FOR AT LEAST A COUPLE HOURS BEFORE THE FRONT ARRIVES FROM WEST TO EAST. WINDS WILL SHIFT TO THE WEST BEHIND THE FRONT...AND BECOME MUCH LIGHTER...AROUND 12-13KT. EVEN LIGHTER SOUTHWEST WINDS ARE EXPECTED TOMORROW UNDER ADVANCING HIGH PRESSURE. SHIMON && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
649 PM CDT SAT APR 6 2013 .DISCUSSION... 259 PM CDT THERE ARE NUMEROUS CHALLENGES WITH THE FORECAST AS THE PATTERN TRANSITIONS TO A MORE ACTIVE ONE...BEGINNING WITH SHOWERS AND SOME SPORADIC THUNDER THIS EVENING AND THEN CARRYING THROUGH THE MIDDLE OF NEXT WEEK. IN ADDITION...THE LIKELY LOCATION OF THE AREA RELATIVE TO SYNOPTIC FEATURES WILL ALLOW FOR TEMPERATURES TO BE HEAVILY DEPENDENT ON CLOUD COVER AND RAIN...ALONG WITH LAKE INDUCED COOLING AT LEAST A FEW OF THE UPCOMING SEVERAL DAYS. NEAR TERM INTO TONIGHT...A FAST PACED BUT MORE AMPLIFIED UPPER LEVEL PATTERN IS ESTABLISHED OVER THE CENTRAL U.S. THIS AFTERNOON WITH A WELL-DEFINED UPPER WAVE ON WATER VAPOR ADVANCING EASTWARD FROM WESTERN IA. A 1000 MB SURFACE LOW REFLECTION ACROSS SOUTHERN MN HAS DEVELOPED AND HELPED TO ESTABLISH STRONG RETURN FLOW WITH WIND GUSTS TO 40 TO 45 MPH AT SEVERAL SITES. THESE WINDS SHOULD DIMINISH GRADUALLY THROUGH THE EVENING HOURS. MOISTURE RETURN HAS STRUGGLED HOWEVER...BOTH AT THE SURFACE AND IN THE DEEP LAYER PER OBSERVATIONS AND PWAT ANALYSIS AND IS A REASON SHOWER COVERAGE IS LIKELY TO BE MORE LIMITED THAN IT COULD BE GIVEN THE UPPER FORCING AHEAD OF THIS WAVE...AND IT WILL TAKE SOME TIME FOR THE VERY DRY LOWER ATMOSPHERE TO SATURATE. A NARROW CORRIDOR OF 700-900 MB MOISTURE TRANSPORT ALONG A MID-LEVEL JET HAS STILL HELPED TO INCREASE ECHOES UPSTREAM DURING THE FIRST HALF OF THE AFTERNOON AND THIS WILL LIKELY BE JUST ENOUGH TO CONTINUE DOING SUCH WITH STEEPENING MID-LEVEL LAPSE RATES IN CONCERT WITH THE NARROW MOISTURE CONVERGENCE. MOST OF THE HIGH-RES CONVECTIVE ALLOWING MODELS PREDICT AN INCREASE IN CONVECTIVE-TYPE ECHOES ACROSS NORTH CENTRAL IL BETWEEN 23Z AND 03Z SHIFTING EASTWARD AND FADING SLOWLY THROUGH EARLY OVERNIGHT AS THE FRONT SHIFTS EAST. WITH SEVERAL OF THESE GUIDANCE MEMBERS INDICATING HIGHER REFLECTIVITY AND A NARROW CORRIDOR OF 200-400 J/KG OF MUCAPE PER THE RAP ALONG THE FRONT...WOULD EXPECT A FEW STORMS WITHIN THE GENERAL SHOWERS. HAVE ADAPTED HOURLY POPS THROUGH THIS EVENING PERIOD OF THE FORECAST. AS PREVIOUS FORECAST DID KEEP MOST OF TONIGHTS TEMPERATURE DROP AFTER THE FRONTAL PASSAGE FROM WEST TO EAST. SUNDAY...HIGH PRESSURE STILL LOOKS TO BRIEFLY PREVAIL FOR THIS PERIOD. THE MOST NOTEWORTHY ASPECT ABOUT THIS IS IT LOOKS TO LINE UP DOWN THE AXIS OF LAKE MICHIGAN BY MIDDAY AND ALLOW FOR A FAIRLY STOUT LAKE BREEZE. THIS WILL BE AIDED BY THE FACT THAT TEMPERATURES SHOULD MODERATE NICELY ON SUNDAY OVER LAND DUE TO ONLY A SMALL WINDOW OF COLD AIR ADVECTION BEHIND THE FRONT TONIGHT AND A DRY AIR MASS AND PREDICTED SUNSHINE DURING SUNDAY. THE TEMPERATURE AND PRESSURE DIFFERENCES WITHIN A LIGHT WIND FIELD SHOULD DRIVE A STRONG LAKE BREEZE...AND THE AFTERNOON TEMPERATURE DROP FOR DOWNTOWN CHICAGO AND OTHER NEAR LAKE AREAS MAY BE AS MUCH AS 15 DEGREES. SUNDAY NIGHT AND MONDAY...AN ACTIVE WEST-TO-EAST PACIFIC JET OVER 120 KT AS SEEN ON HEMISPHERIC WATER VAPOR TODAY WILL DIG ITS WAY INTO THE WESTERN U.S. WITH TROUGH DEVELOPMENT AND UPSTREAM SOUTHWEST FLOW OVER THE MIDWEST. A LEAD IMPULSE IN THIS FLOW IS WELL PREDICTED ON GUIDANCE TO PASS OVER THE AREA DURING LATE SUNDAY NIGHT INTO MONDAY MORNING. THIS LOOKS TO TIGHTEN AN UPPER LEVEL WARM FRONT AND ALLOW FOR SATURATED ISENTROPIC LIFT FOR RAIN SHOWERS. ELEVATED INSTABILITY DOES INCREASE AS THE WARM NOSE BUILDS IN WITHIN THE LOWER LEVELS...AND START THUNDER IN THIS FORECAST PERIOD ITS TOO TOUGH TO DISCERN A PERIOD WHERE THERE WOULD NOT BE A THUNDER CHANCE ALL THE WAY THROUGH WEDNESDAY NIGHT. IN THE WAKE OF THIS LEAD IMPULSE HEIGHTS LOOK TO BUILD ON MONDAY AS THE PRIMARY TROUGH DEVELOPS. ITS A LITTLE INTERESTING AS THERE SHOULD BE A SURFACE WARM FRONT...POSSIBLY DIABATICALLY ENHANCED...LAID OUT SOMEWHERE IN THE CENTRAL IL TO NORTHERN IL REGION. THE ONLY THING IS WITH SHORT WAVE RIDGING HINTED AT THIS FEATURE APPEARS TO BE FAIRLY BENIGN...BUT SOMETHING TO KEEP AN EYE ON. MIDWEEK...AN ACTIVE PERIOD HERE AS PROLONGED SURFACE CYCLOGENESIS BEGINS OVER THE SOUTHERN PLAINS MONDAY NIGHT AND CONTINUES THROUGH TUESDAY WITH THE SURFACE WAVE ADVANCING ENE ON WED. MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THIS...LATCHING MORE ONTO AN EC SOUTHERN SOLUTION. HAVE CONTINUED TO LEAN THAT WAY WITH THE FORECAST WHICH MEANS INHIBITING TEMPERATURES ON WHAT COULD BE GIVEN 850MB TEMPERATURES CLIMBING TO 8C-12C...ESPECIALLY NORTH OF I-80. WITH FLOW OFF THE LAKE TUESDAY AND WEDNESDAY DUE TO THE LOW BEING SOUTHWEST OF THE AREA...TEMPERATURES NEAR THE LAKE WILL REMAIN COOLER. ALSO THIS FORECAST PATTERN MEANS LIKELY SEVERAL BOUTS OF PRECIP WITH THE PROXIMITY OF THE ELEVATED WARM/STATIONARY FRONT. THE 06.12 GFS AND EC RUNS BOTH HAVE OVER TWO AND A HALF INCHES OF RAIN FORECAST AREA WIDE FROM SUNDAY NIGHT THROUGH THURSDAY. WHILE IT IS CHALLENGING TO FOCUS ANY WINDOW FOR CATEGORICAL POPS...IT WOULD SEEM WEDNESDAY AND WEDNESDAY NIGHT WOULD BE THE MOST FAVORED PERIODS FOR STRONGER DYNAMIC FORCING AND POSSIBLY MORE ROBUST ELEVATED CONVECTION WITH THE LARGE SCALE UPPER TROUGH MOVING EASTWARD. COOLING BEHIND THE FRONT LOOKS SOMEWHAT STRONG AND THERE IS A POTENTIAL TO SEE SOME MIX IN THE WAKE OF THE FRONT...BUT CONFIDENCE IS VERY LOW ON HOW THIS SYSTEM WILL EVOLVE AS IT LIFTS OUT. BEYOND...HAVE GONE PRIMARILY WITH A MODEL CONSENSUS AT THE END OF NEXT WEEK AS THE UPPER FLOW PATTERN WORKS FROM BRIEFLY NORTHWEST BACK TO WEST. TEMPERATURES SHOULD GRADUALLY MODERATE BUT CONFIDENCE IS LOW ON PRECIP CHANCES AS THE PATTERN STILL LOOKS DISTURBED. MTF && .FIRE WEATHER... 328 AM...EASTERLY FLOW HAS MAINTAINED MUCH DRIER AIR ACROSS THE REGION AND EXPECT A SLOW RETURN OF LOW LEVEL MOISTURE ACROSS THE AREA TODAY. IT APPEARS DEWPOINTS WILL INCREASE BACK INTO THE 40S...BUT PROBABLY NOT UNTIL LATE AFTERNOON ACROSS WESTERN IL AND THE REST OF THE AREA THIS EVENING. THUS MINIMUM RH VALUES TODAY WILL LIKELY BE IN THE 35-40 PERCENT RANGE AND COULD POSSIBLY DIP INTO THE 30-35 PERCENT RANGE. WHILE THESE EXPECTED VALUES WILL REMAIN ABOVE RED FLAG CRITERIA OF 25 PERCENT...SOUTHERLY WINDS ARE EXPECTED TO QUICKLY INCREASE THIS MORNING WITH GUSTS AS HIGH AS 40 MPH FROM LATE MORNING THROUGH SUNSET WITH THE POTENTIAL FOR HIGHER GUSTS. WHILE THERE COULD BE A FEW LIGHT SHOWERS OR SPRINKLES TODAY...THE BEST TIMING FOR SHOWERS AND A FEW THUNDERSTORMS WILL BE FROM LATE AFTERNOON THROUGH MID/LATE EVENING. TEN HOUR FUEL MOISTURE DIPPED TO 8-9 PERCENT ON FRIDAY AND SIMILAR VALUES ARE POSSIBLE TODAY. AS A RESULT...THERE WILL BE AN INCREASED FIRE DANGER AND WHILE MEETING RED FLAG CRITERIA IS NOT EXPECTED... CONDITIONS WILL NEED TO BE MONITORED THROUGH DAY. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 00Z... * 180-210 DEGREE WINDS THROUGH MID EVENING WITH SOME VARIABILITY TO 220-230 AFTER APPROX 03Z. WINDS SHIFT WEST-NORTHWEST AFTER 06Z WITH COLD FRONTAL PASSAGE. * FREQUENT WIND GUSTS AROUND 25 KT WITH SPORADIC GUSTS CLOSER TO 30 KT MAINLY THROUGH SUNSET...APPROACHING SHOWERS MAY PRODUCE 30 KT GUSTS THROUGH THE EVENING. * STEADIER RAIN SHOWERS ARRIVING TOWARD 01Z WITH A CHANCE FOR SHORT PERIOD OF TS AFTER ABOUT 03Z. * POTENTIAL FOR LOW END MVFR CIGS OVERNIGHT. * LIGHTER NORTHWEST WINDS SUNDAY WITH LAKE BREEZE TURNING WINDS NORTHEAST THEN EAST LATER SUNDAY AFTERNOON. MDB //DISCUSSION...UPDATED 00Z... GUSTY SOUTH-SOUTHWEST WINDS CONTINUE...MAINLY FROM CHICAGO LAND EASTWARD AS LOW PRESSURE TRACKS ACROSS WEST-CENTRAL WISCONSIN AND A COLD FRONT MOVES INTO EASTERN IOWA. GUSTS TO AROUND 25 KT CONTINUE WITH SOME INFREQUENT GUSTS TO AROUND 30 KT STILL POPPING UP BUT THE OVERALL TREND APPEARS TO BE DOWNWARD. SHOWER ARE MOVING IN FROM THE WEST AHEAD OF THE FRONT AND THESE MAY ACT TO BRING STRONGER GUSTS BACK AS THEY PASS. SOME THUNDERSTORMS HAVE DEVELOPED JUST AHEAD OF THE FRONT TOWARDS KCID/KIOW AND THIS ACTIVITY MAY EXPAND IN COVERAGE AS IT MOVES EASTWARD. WILL LEAVE TS MENTION OUT OF THE TAFS FOR NOW WITH POTENTIAL TOO LOW TO INCLUDE...30-40 PERCENT...BUT WILL WATCH TRENDS OVER THE NEXT HOUR OR SO AND AMEND TO ADD IF NECESSARY. THE FRONT WILL CROSS THE AREA LATER THIS EVENING AND BRING A SHIFT TO WEST-NORTHWEST WINDS WITH SPEEDS DIMINISHING. THERE IS STILL SOME POTENTIAL FOR LOWERING CIGS BEHIND THE FRONT TONIGHT BUT CONFIDENCE IS LOW. IF THEY DO OCCUR THEN THEY WILL LIKELY BE LOW END MVFR OR POSSIBLY HIGH END IFR FOR A TIME. WILL ALSO MONITOR THIS TREND OVER THE NEXT FEW HOURS AND LOWER TAF CIGS IF NEEDED. RELATIVELY LIGHT NORTHWEST WINDS WILL OCCUR SUNDAY MORNING BUT HIGH PRESSURE WILL MOVE OVERHEAD SO LIGHT AND VARIABLE WINDS MAY PREVAIL BY AFTERNOON. A LAKE BREEZE WILL LIKELY DEVELOP AND TURN WINDS NORTHEASTWARD ACROSS THE CHICAGO AREA TERMINALS DURING THE AFTERNOON. LOW PRESSURE WILL DEVELOP OVER THE CENTRAL HIGH PLAINS LATER SUNDAY ALLOWING A STEADY EAST WIND TO DEVELOP ACROSS ALL AREAS SUNDAY EVENING WHICH WILL TURN SOUTHEASTERLY INTO MONDAY. SHOWER AND THUNDERSTORM CHANCES INCREASE EARLY SUNDAY NIGHT. MDB //ORD AND MDW CONFIDENCE...UPDATED 00Z... * HIGH CONFIDENCE IN WIND DIRECTION TRENDS THROUGH TONIGHT. * MEDIUM-HIGH CONFIDENCE IN FREQUENT GUSTS TO AROUND 25 KT WITH SPORADIC GUSTS TO 30 KT THROUGH SUNSET. * HIGH CONFIDENCE IN PRECIP TIMING/DURATION...MEDIUM CONFIDENCE IN TS POTENTIAL AND TIMING BUT CHANCE IS TOO LOW TO MENTION IN TAF RIGHT NOW. * LOW CONFIDENCE IN LOW MVFR CIG POTENTIAL OVERNIGHT. * HIGH CONFIDENCE IN WIND TRENDS/LAKE BREEZE SUNDAY. MDB //OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z... MONDAY...SHRA/TSRA LIKELY EARLY. MVFR/BRIEF IFR POSSIBLE EARLY. TUESDAY THROUGH THURSDAY NIGHT...PERIODIC CHANCE FOR SHRA/TSRA. PERIODIC MVFR CIGS/VSBY LIKELY WITH BRIEF IFR POSSIBLE. FRIDAY...PROBABLE VFR. MDB && .MARINE... 241 PM CDT LOW PRESSURE OVER SOUTHERN MINNESOTA THIS AFTERNOON IS LIFTING A STRONG WARM FRONT ACROSS LAKE MICHIGAN TODAY. WINDS OVER THE LAND ARE TOPPING OUT AROUND 35 KT THIS AFTERNOON WITH THESE GALES EXTENDING INTO THE NEARSHORE WATERS WHERE A GALE WARNING REMAINS IN EFFECT THROUGH THIS EVENING. HOWEVER...WITH TEMPERATURES PUSHING 70 ACROSS NORTHERN ILLINOIS/INDIANA...VERY STABLE CONDITIONS ARE SETTING UP OVER THE OPEN WATERS OF THE LAKE AND SHOULD BE INHIBITING THE STRONGER GUSTS FROM REACHING THE LAKE SURFACE. THE LOW WILL MOVE ACROSS NORTHERN LAKE MICHIGAN LATE THIS EVENING WITH A TRAILING COLD FRONT PUSHING ACROSS THE LAKE SHORTLY THEREAFTER WITH WINDS TURNING WESTERLY AND DIMINISHING. ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO MOVE INTO THE REGION MIDWEEK...THOUGH MODELS CONTINUE TO STRUGGLE WITH TRACK AND TIMING MAKING IT DIFFICULT TO PIN DOWN DETAILS REGARDING OVER THE LAKE. CONTINUE TO FAVOR A FARTHER SOUTH SOLUTION SUPPORTED BY THE CONSISTENT ECMWF...WHICH THE LATEST GFS HAS TRENDED TOWARDS. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...NEARSHORE WATERS UNTIL 10 PM SATURDAY. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
327 PM CDT FRI APR 5 2013 .SYNOPSIS... ISSUED AT 109 PM CDT FRI APR 5 2013 12Z UA ANALYSIS HAS AN 850MB COLD FRONT FROM THE MID ATLANTIC STATES INTO SOUTHEAST IOWA. A RIDGE RAN FROM SOUTHERN TEXAS TO LAKE WINNIPEG IN CANADA AND A LLJ RAN FROM WEST TEXAS INTO WESTERN NEBRASKA. SATELLITE TRENDS THROUGH MID DAY SHOW INCREASING MID AND HIGH LEVEL CLOUDS ACROSS THE MID MISSISSIPPI VALLEY. 18Z SFC ANALYSIS HAS A LOW ALONG THE NE/SD BORDER NEAR KIEN WITH A WARM FRONT INTO SOUTH DAKOTA AND THEN DROPPING SOUTH ALONG THE MISSOURI RIVER. THE MODIFIED ARCTIC FRONT WAS INTO THE TENNESSEE VALLEY AND SOUTHERN MISSOURI. DEW POINTS OVER THE GREAT LAKES WERE IN THE TEENS AND 20S WITH 30S AND 40S IN THE CENTRAL AND SOUTHERN PLAINS. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 109 PM CDT FRI APR 5 2013 THE DRY AIR IS HAMPERING THE DEVELOPMENT OF THE WAA PRECIPITATION WING FROM MN INTO WISCONSIN. HOWEVER...RAP TRENDS WITH THE 850-700MB CONDENSATION PRESSURE DEFICITS COMBINED WITH OVERALL FORCING/CONVERGENCE AGREE QUITE NICELY WITH THE PRECIPITATION APPROACHING THE MISSISSIPPI RIVER AROUND KMSP. USING THIS AS A GUIDE THERE MAY BE SOME ISOLATED SHRA/SPRINKLES THAT IMPINGE ALONG THE NORTHERN BORDER OF THE CWFA LATE THIS AFTERNOON AND EARLY EVENING. ONCE THE FORCING SHIFTS NORTHEAST OF THE AREA BY SUNSET...DRY CONDITIONS SHOULD THEN BE SEEN ACROSS THE AREA THROUGH MIDNIGHT. AFTER MIDNIGHT THINGS GET MORE INTERESTING. THE MCS AND LIFT TOOLS ARE SUGGESTING CONVECTION DEVELOPING JUST WEST OF I-35 IN THE STRENGTHENING LLJ BY MIDNIGHT. IF THE RAP TRENDS ARE CORRECT THIS CONVECTION OF SHRA/TSRA SHOULD BE ON THE WESTERN BORDER OF THE CWFA BY 09Z AND OVER THE WESTERN HALF OF THE CWFA BY SUNRISE. THE COMBINATION OF THE LLJ AND STEEP MID LEVEL LAPSE RATES SHOULD MAINTAIN THE CONVECTION AND ALSO RESULT IN WINDS INCREASING DURING THE NIGHT. THE ABOVE MENTIONED CONVECTION SHOULD EXIT THE CWFA BY LATE MORNING AND THERE SHOULD BE A BRIEF PAUSE BEFORE NEW DIURNAL CONVECTION DEVELOPS BY MID DAY AND CONTINUES THROUGH THE AFTERNOON HOURS. LOW LEVEL LAPSE RATES BECOME QUITE STEEP AND THE WAA IS QUITE STRONG ON SATURDAY WHICH WILL ALLOW THE HIGHER MOMENTUM AIR ALOFT TO MIX DOWN. WINDS ARE EXPECTED TO PICK UP SIGNIFICANTLY BY LATE MORNING AND CONTINUE THROUGH THE AFTERNOON. THE SITUATION SATURDAY WILL NEED TO BE WATCHED CAREFULLY. THE POTENTIAL DOES EXIST FOR A LOW END WIND ADVISORY FOR AREAS ALONG AND EAST OF THE MISSISSIPPI FROM LATE MORNING THROUGH THE AFTERNOON HOURS. ..08.. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 109 PM CDT FRI APR 5 2013 SATURDAY NIGHT AND SUNDAY SHOULD BE RELATIVELY QUIET AS A RIDGE OF THE HIGH PRESSURE NOSES INTO THE REGION FROM THE NORTH. SOME LOW CHANCE POPS WERE MAINTAINED EAST OF THE MISSISSIPPI RIVER SATURDAY EVENING TO COVER ANY LINGERING SHOWERS BEHIND THE DEPARTING COLD FRONT. BY SUNDAY MORNING THE COLD FRONT SHOULD BE STALLED OVER CENTRAL OR NORTHERN MO WITH THE HIGH PRESSURE RIDGE OVER THE NORTHERN CWFA. THIS SHOULD KEEP DRY WEATHER OVER MUCH OF THE AREA THROUGH THE DAY SUNDAY. HOWEVER...KEPT SOME LOW POPS GOING IN THE FAR SOUTH IN THE AFTERNOON WITH THE SURFACE FRONT JUST TO THE SOUTH. SUNDAY NIGHT A LOW AMPLITUDE S/W WILL MOVE THROUGH THE REGION SPAWNING SHOWERS AND THUNDERSTORMS ALONG AND NORTH OF THE STALLED FRONT. THE 00Z ECMWF WAS GENERATING SOME QPF WITH THIS FEATURE OVER THE WESTERN CWFA AS EARLY AS SUNDAY AFTERNOON. BUT THE FORCING SHOWN BY THE ECMWF WOULD SHOW MORE FAVORABLE CONDITIONS OVER WESTERN IOWA BEFORE 00Z. OTHER THAN THE LOW CHANCE POPS IN THE SOUTH SUNDAY AFTERNOON DISCUSSED ABOVE...THE SIGNIFICANT POPS WERE LIMITED TO SUNDAY NIGHT WITH LIKELY/S OVER THEN ENTIRE AREA WHEN AN AREA OF SHOWERS AND THUNDERSTORMS SHOULD MOVE EAST ACROSS THE REGION AHEAD OF THE MID LEVEL SHORTWAVE. AT THIS POINT THE SEVERE THUNDERSTORMS THREAT LOOKS NIL DUE LOW INSTABILITY AND UNIMPRESSIVE FORCING. PW/S OVER THE AREA SUNDAY NIGHT ARE EXPECTED TO BE AROUND AN INCH SUGGESTING GENERAL RAINFALL AMOUNTS OF A HALF TO THREE QUARTERS OF AN INCH. THE HIGHER AMOUNTS WOULD FAVOR THE SOUTH CLOSE TO THE SURFACE FRONT. SHOWER AND THUNDERSTORM CHANCES WILL REMAIN OVER THE AREA MONDAY THROUGH WEDNESDAY. THE LARGE TROF DEVELOPING OVER THE WESTERN U.S. WILL CONTINUE TO FEED AMPLE MOISTURE INTO THE CENTRAL U.S. WHERE A FRONTAL BOUNDARY WILL REMAIN. DURING THIS TIME FRAME...TUESDAY INTO WEDNESDAY HAVE THE BEST CHANCE FOR SIGNIFICANT RAINS WHEN THE MODELS SHOW A SURFACE LOW EJECTING NORTHEAST OUT OF THE SOUTHERN PLAINS AHEAD OF THE UPPER TROF. EVEN THOUGH THIS FEATURE IS SHOWN BY ALL MODELS THERE CONTINUES TO BE A VARIETY OF SOLUTIONS ON THE DETAILS OF THE TRACK AND TIMING. THE 12Z ECMWF HAS SHIFTED THE TRACK FURTHER SOUTHEAST SUGGESTING THE SIGNIFICANT RAINS WILL MISS THE FORECAST AREA. THE GEM/GFS TRACK THE SYSTEM OVER IOWA TUESDAY OR TUESDAY NIGHT SUPPORTING ANOTHER ROUND OF AT LEAST MODERATE RAINS. GIVEN THE AMOUNT OF MOISTURE INPLACE AND A SURFACE BOUNDARY IN THE AREA THE THREAT OF RAIN STILL LOOKS GOOD MONDAY THROUGH WEDNESDAY WITH THE BIGGEST QUESTION NOW BEING THE RAINFALL AMOUNTS. SO HAVE CONTINUED TO MENTION LIKELY POPS OVER MUCH OF THE AREA FOR SHOWERS AND THUNDERSTORMS. THEN WEDNESDAY WHEN THE UPPER TROF MOVES THROUGH...POPS WERE BACKED DOWN TO CHANCE CATEGORY. COLDER AIR ADVECTING IN BEHIND THE TROF WEDNESDAY NIGHT COULD PRODUCE A MIX OF RAIN AND SNOW ESPECIALLY NORTH. HOWEVER PRECIP AMOUNTS SHOULD BE LIGHT MAKING IT UNLIKELY THAT ANY ACCUMULATION WILL OCCUR. PRECIP COULD LINGER INTO THURSDAY AND THURSDAY NIGHT WITH H8 TEMPS REMAINING BELOW ZERO. HOWEVER... TEMPERATURES NEAR THE SURFACE SHOULD BE WARM ENOUGH FOR ALL RAIN. DEEP SOUTHERLY FLOW AND HIGH MOISTURE LEVELS WILL KEEP TEMPERATURES ON THE MILD SIDE EARLY NEXT WEEK...BUT BELOW NORMAL READINGS WILL RETURN FOR THE END OF THE WEEK AS THE COLDER AIR MOVES IN BEHIND THE DEPARTING UPPER TROF. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 109 PM CDT FRI APR 5 2013 VFR WX WILL BE SEEN THROUGH 06Z/06 WITH A POSSIBLE VCSH AT KDBQ THROUGH SUNSET. AFT 06Z/06 MAINLY VFR WX IS EXPECTED TO CONTINUE WITH POSSIBLE SHRA/TSRA AFFECTING ALL TAF SITES AFT 09Z/06. THE POTENTIAL STILL EXISTS FOR LLWS IN THE 09Z-15Z/06 TIME FRAME. NEW CONVECTION IS EXPECTED TO DEVELOP ACROSS IOWA/ILLINOIS AFT 15Z/06 AND BECOME MORE NUMEROUS AFT 18Z/06. ..08.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...08 SHORT TERM...08 LONG TERM...DLF AVIATION...08
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1130 PM CDT THU APR 4 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 306 PM CDT THU APR 4 2013 LIGHT SURFACE PRESSURE GRADIENT IS EVIDENT IN 20Z RAP ANALYSIS. THIS LIGHT PRESSURE GRADIENT IS RESPONSIBLE FOR LIGHT WINDS WHICH ARE EVIDENT IN SURFACE OBSERVATIONS ACROSS THE FORECAST AREA THIS AFTERNOON. EXPECT THESE LIGHT WINDS TO EVENTUALLY SHIFT TO THE SOUTH OVERNIGHT TONIGHT AS A SURFACE LOW COMES INTO FORMATION OVER THE HIGH PLAINS. SOUTHERLY WINDS WILL INCREASE THROUGH THE DAY ON FRIDAY TO AROUND 20 TO 25 MPH...WITH GUSTS TO AROUND 30 MPH. DEEP MIXING WILL CAUSE ALLOW FOR LOW LEVEL WINDS AROUND 850 MB TO COME TO THE SURFACE...WHICH MAY BRING WARMER/DRYER CONDITIONS AND STRONGER WIND GUSTS. THIS WILL HAVE FIRE WEATHER IMPLICATIONS...WHICH ARE DISCUSSED IN THE FIRE WEATHER DISCUSSION BELOW. AT THIS TIME EXPECT VERY HIGH FIRE DANGER FOR MOST OF THE AREA THROUGH THE DAY ON FRIDAY. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 306 PM CDT THU APR 4 2013 FRIDAY NIGHT THROUGH SUNDAY...FRIDAY NIGHT LEE SIDE LOW PRESSURE DEEPENS OVER THE HIGH PLAINS INCREASING THE PRESSURE GRADIENT ACROSS THE AREA. THEREFORE THE WINDS WILL CONTINUE TO BE GUSTY THROUGH THE OVERNIGHT HOURS ESPECIALLY ACROSS EASTERN KANSAS. THIS WILL KEEP LOW TEMPERATURES FRIDAY NIGHT IN THE LOW 50S. A SOUTHWESTERLY LOW LEVEL JET INCREASES FRIDAY NIGHT BRINGING LIMITED MOISTURE TO THE REGION. MEANWHILE A SHORTWAVE ADVANCES EASTWARD INTO NEBRASKA AND EVENTUALLY IOWA ON SATURDAY. IT APPEARS THAT THE STRONGER LIFT ASSOCIATED WITH THE WAVE WILL BE NORTH OF THE AREA FRIDAY NIGHT AND SATURDAY MORNING. THERE IS SLIGHT CHANCE OF SOME WEAK LIFT EXTENDING SOUTH INTO KANSAS SO COULD NOT RULE OUT AN ISOLATED SHOWER FRIDAY NIGHT. A WEAK COLD FRONT ASSOCIATED WITH THE WAVE WILL PUSH SOUTHWARD THROUGH THE AREA DURING THE DAY ON SATURDAY SHIFTING THE WINDS TO THE NORTH. THE FRONT WILL RETREAT BACK TO THE NORTH ON SUNDAY AND SETS UP SOMEWHERE IN NORTHEAST KANSAS. A WEAK SHORTWAVE EMBEDDED IN THE ZONAL MID LEVEL FLOW PROGRESSES EASTWARD ACROSS KANSAS DURING THE DAY PROVIDING LAGER SCALE LIFT. SOUTHERLY LOW LEVEL FLOW WILL INCREASE THE MOISTURE RETURN ACROSS THE AREA AS ML CAPE VALUES APPROACH 500 J/KG AIDING IN THUNDERSTORM DEVELOPMENT. MID LEVEL FLOW ALSO INCREASES SUNDAY WITH 0-6 KM BULK SHEAR VALUES AROUND 40 KTS WHICH SUPPORTS THE CHANCE OF STRONGER ORGANIZED THUNDERSTORMS SUNDAY AFTERNOON AND OVERNIGHT. EXTENDED FORECAST (SUN NIGHT-THURS)...AN ACTIVE PATTERN SETTING UP THROUGH THIS PERIOD...AND SEVERE WEATHER APPEARS INCREASINGLY LIKELY....HOWEVER TIMING AND PLACEMENT REMAINS SOMEWHAT UNCERTAIN. SUNDAY NIGHT THE GFS AND A SOMEWHAT FASTER EC BRING A SHORTWAVE OVER THE WARMFRONT PROGGED E/W OVER OUR AREA...WITH THE EC HOLDING THE FRONT FARTHER SOUTH THAN THE GFS. ENOUGH CAPE AND SHEAR PRESENT THAT SOME OF THE STORMS OVERNIGHT COULD BRING HAIL. THE ENSUING WEATHER FOR MONDAY WILL BE DEPENDENT ON HOW FAR NORTH THE WARMFRONT LIFTS DURING THE DAY. EC AND GFS BOTH BREAK OUT CONVECTION NEAR THE BOUNDARY AND LESS SO IN THE WARM SECTOR MONDAY EVENING THROUGH THE MORNING HOURS ON TUESDAY. SEVERE WEATHER POTENTIAL CONTINUES TO INCREASE INTO TUESDAY AND TUESDAY AFTERNOON AS WESTERN TROF APPROACHES...AND SHEAR AND INSTABILITY ALSO INCREASE AND MOVE NORTH ACROSS THE CWA WITH THE WARM SECTOR. DIFFERENCES INCREASE BEYOND TUESDAY AS GFS MOVES THE COLDFRONT THROUGH QUICKLY WITH EC DROPPING A CLOSED UPPER LOW ACROSS EASTERN KANSAS AND THE FRONT MOVING THROUGH WEDNESDAY EVENING. WHILE WED/THURS WILL BRING A COOL END OF THE WEEK...MUCH UNCERTAINTY WITH PRECIP AMOUNTS AND TYPES. 67 && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1129 PM CDT THU APR 4 2013 VFR EXPECTED THROUGH THE PERIOD. WINDS WILL BE THE MAIN CONCERN FOR THE FORECAST AS THEY WILL BEGIN TO INCREASE BY 16Z TO AROUND 16 KTS WITH GUSTS AS HIGH AS 29 KTS IN THE AFTERNOON. PRESSURE GRADIENT WILL REMAIN TIGHT EVEN AFTER SUNSET WHERE THE GUSTS MY SUBSIDE AFTER 02Z...BUT WINDS WILL REMAIN AROUND 15-19 KTS. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...LEIGHTON LONG TERM...67 AVIATION...53
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
746 PM EDT SAT APR 6 2013 .SYNOPSIS... HIGH PRESSURE AND DRY WEATHER WILL CONTINUE OVERNIGHT. A FRONTAL SYSTEM WILL APPROACH ON SUNDAY BRINGING SCATTERED SHOWERS. THE FRONT WILL LINGER NEARBY INTO NEXT WEEK WITH A CONTINUED CHANCE OF SHOWERS. && .NEAR TERM /THROUGH SUNDAY/... 630 PM UPDATE...TEMPERATURES DROPPING EARLY THIS EVENING WITH CONTINUED LOW DEW POINTS. HRRR SUGGESTING NO LOW CLOUDS OVERNIGHT WITH LACK OF LOW LEVEL MOISTURE AND ONLY SCATTERED TO BROKEN MID DECK AND CIRRUS. WILL ADJUST TEMPERATURE TREND AND LOWER MINIMUMS SLIGHTLY GIVEN DEW POINTS AND EXPECTED CLOUDS. PREVIOUS DISCUSSION FOLLOWS... DEW POINTS HAVE LARGELY RUN IN THE SINGLE DIGITS THROUGH MOST OF THE AFTERNOON TODAY...WITH A FEW LOCATIONS JUST SOUTH OF OUR AREA IN WEST VIRGINIA RUNNING WELL BELOW ZERO. THE RESULT HAS BEEN AN EXTREMELY DRY DAY ACROSS THE FORECAST AREA WITH ONLY CIRRUS GENERALLY FILTERING THE SUN. AS THE NIGHT ENSUES...MORE SIGNIFICANT LARGE SCALE LIFT AND MOISTURE SLOWLY ENCROACHES FROM THE WEST...HOWEVER GIVEN THAT IT HAS FAILED TO EVEN REACH THE MIDDLE AND UPPER MISSISSIPPI VALLEY THIS AFTERNOON...AND THE FACT THAT THE BEST UPPER LEVEL RH FIELDS FAVOR CIRRUS AND MID-CLOUD DEVELOPMENT LARGELY NORTH OF THE AREA...THE NIGH SHOULD BE DRY ALMOST EVERYWHERE IN THE FORECAST AREA...WITH ONLY HIGH CLOUDS FILTERING THE MOON OUT FROM TIME TO TIME. DUE TO THE RIDICULOUSLY DRY IN SITU BOUNDARY LAYER AND LACK OF SIGNIFICANT LAYER RH COMING INTO THE FORECAST AREA BEFORE MORNING...ALL POPS WERE REMOVED FOR THE NIGHT. WITH OUR EXTREMELY DRY BOUNDARY LAYER THIS AFTERNOON AND LESS SIGNIFICANT CLOUD EXPECTATIONS...LOW TEMPERATURES WERE CUT A BIT OVERNIGHT...HOWEVER IT WILL NOT BE ANYWHERE NEAR AS COLD AS RECENT NIGHTS. ADDITIONALLY...SURFACE FLOW SHOULD SLOWLY TURN SOUTHERLY...WHICH WILL ALSO WORK TO LIMIT THE DIURNAL FALL POTENTIAL. FRIES && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... NAM AND GFS SOLUTIONS HAVE COME INTO DECENT AGREEMENT WITH A FRONTAL PASSAGE THROUGH THE AREA ON SUNDAY. MOISTURE ALONG AND AHEAD OF THE FRONT IS RATHER LIMITED AS IT MOVES INTO OUR BONE DRY ENVIRONMENT...SO QPF VALUES WERE CUT BACK QUITE A BIT. HOWEVER...DECENT FRONTOGENETICAL FORCING AS WELL AS SOME SHALLOW INSTABILITY SHOULD BE ENOUGH TO GENERATE A LINE OF LIGHT SHOWERS ALONG THE FRONT AS IT MOVES THROUGH SUNDAY. THE MODEL CONSENSUS FAVORS A STALLING OF THE FRONT ACROSS NORTHERN WEST VIRGINIA SUNDAY NIGHT BEFORE IT TURNS NORTHWARD AS A WARM FRONT ON MONDAY. THIS BRINGS PROGRESSIVELY WARMER AIR INTO THE AREA EARLY NEXT WEEK. POPS FOR SHOWERS WERE CONTINUE THROUGH MONDAY NIGHT BEFORE BEING INCREASED AGAIN ON TUESDAY. WHILE AGREEMENT ON THE PLACEMENT OF THE FRONT BY TUESDAY BECOMES LESS PRONOUNCED...THE ECMWF/GFS/NAM ALL LIKE THE IDEA OF TRACKING A WAVE DOWN THE FRONT BY THE AFTERNOON HOURS. THIS WOULD ADD ADDITIONAL LIFT AND SHEAR ALONG THE FRONTAL ZONE. IN ADDITION...SYNOPTIC LIFT MAY BE ENOUGH TO OVERCOME A MODERATELY STRONG CAP ALONG THE FRONTAL BOUNDARY. IF THIS OCCURS...A FEW HUNDRED J/KG OF CAPE ARE PRESENT BY TUESDAY THAT DOES MANAGE TO REACH UP TOWARD THE -30C ISOTHERM. THIS WOULD YIELD A CHANCE OF THUNDERSTORMS BY TUESDAY AFTERNOON. THUNDERSTORMS WERE THUS ADDED TO THE FORECAST FOR TUESDAY AFTERNOON...HOWEVER REMAIN OUT OF THE FORECAST BEFORE THAT TIME DUE TO SHALLOW INSTABILITY AND CAPPING. FRIES && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... OVERALL...CONFIDENCE IN EXTENDED FORECAST IS LOWER THAN NORMAL...SIMILAR TO YESTERDAY. FRONT WILL STILL BE HUNG UP TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...PROBABLY TO THE NORTH OF THE REGION. ALTHOUGH COLD FRONT WILL LIKELY BEGIN TO CROSS THE REGION ON THURSDAY...GFS/ECMWF CANNOT DECIDE WHETHER THE COLD FRONT WILL TAKE 24 OR 48 HOURS TO PUSH ALL THE WAY THROUGH. HAVE BUMPED UP POPS TO LIKELY THURSDAY NIGHT...BUT OTHERWISE MADE LITTLE CHANGES TO POPS OR TEMPERATURES. TEMPERATURES SHOULD BE ABOVE NORMAL WED/THURS...DROPPING TO BELOW NORMAL FRI/SAT. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... EXPECT SCT TO BKN VFR MID AND HIGH CLOUDS THIS EVENING. LOW LEVEL WIND SHEAR IN THE TAFS OVERNIGHT WITH LOW LEVEL JET DEVELOPING FROM THE SOUTHWEST ALOFT WHILE SURFACE LOOKS TO DECOUPLE A BIT WITH A LIGHTER SOUTH TO SOUTHEAST WIND. HAVE GONE WITH SHOWERS/SPRINKLES MOST LOCATIONS BEGINNING LATE MORNING NORTH TO LATE AFTERNOON SOUTH. FRONT CROSSING THE REGION BETWEEN 15Z- 21Z. WHILE THERE IS SOME MODEL GUIDANCE THAT CIGS COULD DROP TO MVFR IN SHOWERS...BELIEVE GENERAL VFR IS STILL BEST FORECAST. .OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/... THE BOUNDARY SHOULD SHIFT SOUTH OF THE REGION SUNDAY NIGHT...THEN BE PULLED NORTHWARD ONCE AGAIN ON MONDAY AS LOW PRES DIGS ACRS THE GREAT LAKES. FRONT POSITIONING IS QUESTIONABLE THROUGH MUCH OF THE WEEK...SO OCCASIONAL RESTRICTIONS SHOULD BE ANTICIPATED. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
138 PM EDT FRI APR 5 2013 .UPDATE... ISSUED AT 1254 PM EDT FRI APR 5 2013 GIVEN LARGER SPRING STORM IS QUICKLY ON THE APPROACH...THOUGHT IT WOULD BE GOOD TO PROVIDE UPDATE IN TERMS OF EXPECTED STORM INTENSITY/PTYPE AND HEADLINES. SFC TROUGH THAT EVENTUALLY WILL DEVELOP INTO CLOSED OFF LOW OVER WESTERN LAKES LATER SATURDAY IS CURRENTLY ALLIGNED FROM SOUTHERN PORTIONS OF ALBERTA AND SASKATCHEWAN INTO NORTHERN US ROCKIES. 12Z RAOBS AND WV LOOP SHOW H5 TROUGH PUSHING OUT OF WA/OR...WHILE TROUGH AT H85 AND H7 IS CLOSER TO THE MAIN SFC LOW. SNOW IS AS CLOSE AS ND/SASKATCHEAN BORDER ON EDGE OF H8-H7 FRONTOGENESIS. NAM/GFS AND REGIONAL GEM INITIALIZED LARGER SCALE FEATURES WELL BUT DIFFER ON CRITICAL THERMAL DETAILS FOR SATURDAY. OVERALL...AT THE LEAST...WINTER WEATHER ADVISORIES WILL BE POSTED LATER THIS AFTN FOR ALL OF CWA. ALREADY COORD WITH DLH AND GRB WHICH HAVE ADVYS UP AND ALSO WITH APX. SOME AREAS MAY NEED WARNINGS BUT IT WILL DEPEND ON WHERE PTYPE REMAINS MOSTLY SNOW FOR THE EVENT. UNFORTUNATELY...THIS IS NOT CLEAR CUT EVEN WITHIN 24 HRS AS SOME MODELS /GFS AND UKMET/ ARE PRETTY WARM AT H85-H8 DURING THE AFTN HOURS ON SATURDAY /UP TO +3C AT H85/ WHILE NAM/REGIONAL GEM AND 00Z ECMWF ARE NOT AS WARM. THIS IS ESPECIALLY TOUGH CONSIDERING THEY ARE FAIRLY SIMILAR WITH H85/H7/H5 FEATURES. AS WOULD BE EXPECTED WITH THERMAL PROFILES...GFS/SREF ARE SLIGHTLY FARTHER NORTH WITH SFC LOW. GIVEN STEEP LAPSE RATES IN MID-LEVELS FEEDING INTO AREA OF PRECIPITATION OVER UPR MICHIGAN...THERE IS ALSO CONCERN CONVECTION WILL MODULATE INTENSITY AND PTYPE OVER THE CWA. AT THIS POINT...FAR SOUTH SEEMS PRETTY CERTAIN TO SEE MAINLY RAIN BY SATURDAY AFTN SO SNOW AMOUNTS WILL ULTIMATELY BE HELD DOWN FROM IMT TO ESC AND CERTAINLY SOUTH TO MNM. GOGEBIC AND IRON TOUGH CALL AS INITIAL WARM NOSE MAY RESULT IN MIX OF SLEET/SNOW AND EVEN RAIN LATE TONIGHT INTO SATURDAY MORNING BUT PRECIP WOULD TURN BACK TO MAINLY SNOW ON SATURDAY AFTN AS H7-H5 TROUGH/PRIMARY SHORTWAVES/LARGER SCALE LIFTING AND DYNAMIC COOLING ARRIVE. MUCH MORE OF A QUESTION IN THE TIER OF COUNTIES NORTH...FROM ONTONAGON/SOUTHERN HOUGHTON THROUGH BARARA/MARQUETTE AND EAST TO ALGER/SCHOOLCRAFT/LUCE COUNTY. IN THESE AREAS INITIAL SHOT OF PRECIP SATURDAY MORNING SHOULD REMAIN MOSTLY SNOW AS THINK THAT DYNAMIC COOLING TIED TO STRONG H8-H5 FGEN OFFSETS SHALLOW WARM LAYER H85-H8 AROUND +1C. INITIAL SURGE OF PRECIP DRIVEN BY 295-305K /H85-H5/ ISENTROPIC ASCENT AND DIVERGENCE ALOFT FROM LARGE JET STREAK OVER ONTARIO INTO QUEBEC COULD END AS MIX OF SLEET/SNOW AS DYNAMIC COOLING FADES BTWN 15Z-18Z. STILL MANY DETAILS TO BE SORTED OUT BUT WINTER WEATHER STATEMENT WITH FINAL HEADLINE DECISIONS WILL BE OUT LATER THIS AFTN. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 622 AM EDT FRI APR 5 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW CONFLUENT NW FLOW ALF OVER THE GRT LKS DOWNSTREAM OF RDG OVER THE ROCKIES. AT THE LLVLS...THE CWA IS DOMINATING BY A NW FLOW OF COLDER AIR IN THE WAKE OF THU COLD FROPA AND AHEAD OF SFC HI PRES NEAR LK WINNIPEG. SINCE THE 00Z INL RAOB SHOWED A VERY DRY...INVERTED V PROFILE AND RECENT SFC OBS INDICATE FAIRLY LARGE SFC T/TD SPREADS...SKIES ARE MOCLR OVER UPR MI AS OF 06Z. BUT THE 00Z YPL RAOB DEPICTED A SOMEWHAT MOISTER...BUT STILL WELL MIXED...SFC-H85 T/TD PROFILE WITH AN H85 TEMP DOWN TO -16C. FARTHER UPSTREAM...A SHRTWV IS MOVING INTO THE PAC NW. WAD MID/HI CLDS WELL E OF THIS DISTURBANCE ARE SPREADING INTO THE NRN PLAINS. TODAY...ALTHOUGH SKIES ARE MOCLR EARLY THIS MRNG...SUSPECT SOME LK CLDS/EVEN SOME -SHSN MIGHT DVLP OVER AREAS E OF MQT AS THE MOISTER...COLDER AIRMASS SHOWN ON THE 00Z YPL RAOB WITH H85 TEMPS AS LO AS -15C IMPACT THIS PART OF THE CWA. OVER THE W HALF...THE VERY DRY 00Z INL RAOB IS MORE REPRESENTATIVE OF THE SOURCE AIRMASS. SO REMOVED POPS/DIMINISHED FCST CLDS IN THIS AREA. BUT EVEN OVER THE E...GENERALY ACYC NATURE OF THE FCST LLVL FLOW AS WELL AS HIER SFC T/TD DEPRESSIONS EVEN FARTHER E N OF LK SUP SUG ANY SN ACCUMS WL BE NEGLIGIBLE IF SHSN DO FORM AT ALL. WITH DAYTIME HEATING/LARGE SCALE SUBSIDENCE AS SFC HI BLDS OVER THE W HALF OF THE CWA BY 18Z...EXPECT ANY LES OVER THE E TO DIMINISH BY NOON. DIURNAL CU/SC THAT DVLP WITH DAYTIME HEATING/MIXING UNDER LINGERING H85 THERMAL TROF WL TEND TO DIMINISH OVER AT LEAST THE W AND CENTRAL WITH MORE EMPHATIC DRYING/ QUICKER TRANSITION TO MORE ACYC FLOW...BUT SC MAY LINGER LONGER OVER THE E WHERE THE H85 TEMPS WARM ABV -10C ONLY TOWARD 00Z. MIXING TO H85 AS OBSVD ON UPSTREAM 00Z RAOBS YIELDS HI TEMPS IN THE UPR 30S/ LO 40S OVER THE W...BUT ONLY 30 TO 35 OVER THE CNTRL AND E WHERE LOWER H85 TEMPS LINGER LONGER. WITH WEAKER PRES GRADIENT ARRIVING WITH SFC HI CENTER...LK BREEZES WL MAINTAIN LOCAL COOLING NEAR THE SHORES. SOME HI CLDS WL ARRIVE OVER THE W IN THE AFTN WELL IN ADVANCE OF PAC NW SHRTWV MOVING THRU THE NRN ROCKIES. TNGT...AS SHRTWV MOVES THRU THE NRN PLAINS AND ASSOCIATED SFC LO SHIFTS TO SW MN BY 12Z SAT...EXPECT THICKENING CLDS IN THE DVLPG WAD PATTERN BTWN THE DEPARTING HI AND INCOMING LO PRES. VIGOROUS ISENTROPIC ASCENT SHOWN ON THE 280-295K ISENTROPIC SFCS IS FCST TO SPREAD W-E ACRS THE CWA AND SLOWLY SATURATE THE VERY DRY ANTECEDENT LO-MID LVLS. FAVOR THE SOMEWHAT SLOWER 00Z NAM/CNDN AND 12Z ECMWF FOR TIMING LEADING EDGE OF PCPN TIED TO H5-7 FGEN AXIS OVER THE GFS...WHICH APPEARS TO GENERATE PCPN TOO DEEP INTO THE LINGERING DRY AIR. THESE FAVORED MODELS INDICATE PCPN WL REACH A LINE FROM MUNISING-MANISTIQUE BY 12Z SAT... SO RESTRICTED CATEGORICAL POPS TO THE W OF THAT AXIS. FAVORED MODEL QPF INDICATES 2 TO 3 INCHES OF SN OVER THE SW CWA BY 12Z SAT EVEN THOUGH RATHER NARROW/HI DGZ CENTERED ARND 15K FT WL LIMIT SN/WATER RATIOS. EXPECT THE LOWEST MIN TEMPS OVER THE INTERIOR E...WHERE THE CLDS WL ARRIVE LATEST AND WINDS BE LGT IN THE EVNG TO ALLOW FOR GOOD RADIATIONAL COOLING. FOLLOWED A NON-DIURNAL CURVE WITH TEMPS FALLING TO THE LOWEST LVL FAIRLY EARLY...THEN STEADY OR SLOWLY RISING. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 622 AM EDT FRI APR 5 2013 MAIN FCST CONCERNS FOCUS ON SYSTEM FOR SATURDAY...PTYPE CONCERNS...POSSIBLE HEADLINES AND SNOW AMTS. ACTIVE SHORTWAVE NOW MOVING IN OFF THE PACIFIC NW AS NOTED ON WATER VAPOR LOOP IS EXPECTED TO TRACK DUE E...REACHING THE WRN GREAT LAKES SAT. WHILE MODELS HAVE COME INTO BETTER AGREEMENT WITH TRACK/TIMING OF SHORTWAVE AND ASSOC SFC LOW SOME IMPORTANT MODEL DIFFERENCES REMAIN IN THERMAL FIELDS. CONFIDENCE IS HIGH THAT ALL OF THE FCST AREA WILL SEE PCPN...SO HIGH CATEGORICAL POPS WILL BE PAINTED ACROSS THE CWA. RIGHT ENTRANCE OF UPPER JET ASSOCIATED WITH ERN CANADA TROF WILL PROVIDE LARGER SCALE ENHANCEMENT TO UPWARD MOTION...AS A FAIRLY VIGOROUS FRONTOGENESIS SIGNATURE WILL AID PCPN INTENSITY ON THE SMALLER SCALE. IT APPEARS THAT THERE MAY BE 2 PERIODS OF FGEN FORCING...ONE INITIALLY LATE TONIGHT/SAT MORNING THAT TRANSLATES ACROSS THE AREA...THEN A SECOND SAT AFTN/EVENING THAT WOULD FAVOR CNTRL/ERN UPPER MI FOR HEAVIER PCPN. WITH MIXING RATIOS OF 4-5G/KG AND CLOSE TO 12HRS OF ASCENT...THERE COULD BE 6 TO POSSIBLY AS MUCH AS LOCALLY 8-10 INCHES OF HVY/WET SNOW ALONG THE AXIS OF HEAVIEST PCPN WHERE PTYPE IS ALL SNOW. SO...DETERMINING THE CONFIGURATION OF PTYPES WILL BE CRITICAL. IS STILL APPEARS THAT PTYPE WILL BE ALL SNOW ACROSS THE FCST AREA AS PCPN DEVELOPS TONIGHT ...AND THAT SNOW MAY FALL LONG ENOUGH SO THAT A FEW INCHES OF SNOW ACCUMULATE EVEN IN AREAS THAT SEE A MIX OR CHANGE TO RAIN DURING THE DAY SAT. DURING THE DAY SAT...UNCERTAINTY GROWS IN HOW FAR N WARMING OCCURS. THE 06Z GFS AND NAM BRINGS 0C 850MB ISOTHERM AND CRITICAL 1000-850MB THICKNESS FAR ENOUGH N SO THAT PERHAPS ONLY WEST AND NW UPPER MI REMAINS MOSTLY SNOW SAT AFTN/EVENING. THE LOCAL WRF-ARW AND REG-GEM ARE FARTHER S WITH THESE TEMP PARAMETERS AND ARE GENERALLY MORE IN LINE WITH THE ECMWF...SUGGESTING MUCH OF NRN UPPER MI WILL STAY MOSTLY SNOW. FCST SOUNDINGS STILL SUGGEST THAT A NARROW ZONE OF SLEET IS ALSO POSSIBLE IN THE TRANSITION ZONE BTWN MOSTLY SNOW NORTH TO MOSTLY RAIN SOUTH ON SAT. CONSIDERED ISSUING A WATCH FOR SOME THE NRN COUNTIES IN SWATH OF EXPECTED HEAVIER PCPN WHERE PTYPE WILL BE MOSTLY SNOW...BUT GIVEN CONTINUED UNCERTAINTIES WITH PTYPE AND ULTIMATE ACCUMS DECIDED TO KEEP AN SPS GOING HIGHLIGHTING THE POTENTIAL FOR VERY HVY/WET SNOW THAT WILL BE DIFFICULT TO SHOVEL/PLOW AND WILL LEAD TO VERY DIFFICULT TRAVEL CONDITIONS. ON SUN...SFC HIGH PRES WILL NOSE INTO THE UPPER LAKES BEHIND SYSTEM...BRINGING AN INFLUX OF DRIER AIR. DAYTIME TEMPS SHOULD RECOVER WELL INTO THE 30S/LWR 40S IN THE AFTN WITH SOME INCREASE IN SUNSHINE DURING THE DAY. FCST FOR MON THRU THU REMAINS UNCERTAIN. MUCH OF THE FCST WILL HINGE ON THE STRENGTH OF THE LINGERING ERN CANADA TROF UNDER THE WEAKENING NEGATIVE AO/NAO PATTERN. OTHER THAN A SHOWING A WEAK NRN PLAINS SHORTWAVE MOVING THROUGH THE AREA LATE SUNDAY NIGHT INTO MONDAY...THE LATEST ECMWF IS SIMILAR TO RECENT RUNS SHOWING A STRONGER AND MORE PERSISTENT ERN CANADIAN TROF WHICH KEEPS A DRIER WNW FLOW ACROSS THE UPPER LAKES FOR THE EARLY PART OF NEXT WEEK. THIS IDEA ALSO WOULD GO ALONG WITH THE GENERAL PERSISTENT PATTERN WHICH HAS DOMINATED THE REGION FOR THE LAST SEVERAL WEEKS...ALTHOUGH IT REMAINS TO BE SEEN HOW LONG PATTERN WILL PERSIST GIVEN EXPECT WEAKENING OF HIGH LATITUDE BLOCKING. THE 12Z ECMWF DOES FINALLY BRING PCPN INTO THE FCST AREA ON WED NIGHT AND THU...MAINLY IN FORM OF SNOW...AS MAIN PIECE OF ENERGY FROM WRN CONUS TROF EJECTS NE TOWARD THE GREAT LAKES. MEANWHILE...THE LATEST 00Z RUN OF THE GFS QUICKLY WEAKENS THE ERN CANADIAN TROF AND PUSHES IT EAST ALLOWING FOR A STRONG SRN STREAM SHORTWAVE TO EJECT TOWARD THE UPPER GREAT LAKES FM BASE OF WRN CONUS TROF. THE GFS SHOWS 8H TEMPS RISING TO 10-12C BY TUE NIGHT INTO WED ACCOMPANIED BY A SLUG OF GULF MOISTURE (250-300 PCT OF NORMAL PWAT VALUES) WHICH WOULD YIELD A THREAT OF MODERATE TO HEAVY RAIN TO THE FCST AREA TUE NIGHT INTO WED. THE 12Z GEM-NH GENERALLY LENDS MORE SUPPORT TO ECMWF SOLN ALTHOUGH IT ALSO TENDS TO BREAK DOWN ERN CANADIAN TROF QUICKER THAN ECMWF. GIVEN CONSIDERABLE MODEL UNCERTAINTY...WILL CONTINUE SIMPLE CONSENSUS APPROACH TO FCST KEEPING ONLY SCHC POPS FOR MON INTO TUE THEN INCREASE POPS TO 30-40 PCT CHC FOR WED AND THU WITH THE IDEA THAT ERN CANADA TROF WILL WEAKEN ALLOWING FOR MORE ENERGY FROM WRN CONUS TROF TO REACH UPPER GREAT LAKES. TEMPS SHOULD REMAIN BLO NORMAL THRU THE PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 135 PM EDT FRI APR 5 2013 HIGH PRESSURE MOVING OVER THE AREA THIS AFTERNOON AND EVENING SHOULD KEEP VFR CONDITIONS AT EACH TAF SITE. LATE TONIGHT THROUGH SATURDAY A LOW PRESSURE SYSTEM OVER THE NORTHERN PLAINS WILL SHIFT EASTWARD INTO THE AREA INTRODUCING A CHANCE OF SNOW TO ALL TAF SITE AS WELL AS A MIXTURE OF SLEET AT THE IWD TAF SITE. THE BETTER MOISTURE AND LIFT WILL MOVE INTO THE IWD SITE AROUND 06Z TONIGHT...REACHING THE SAW SITE BY 10Z. AS THE BETTER LIFT/MOISTURE PASSES OVER THE TAF SITES EXPECT SNOW TO INTENSIFY EFFECTIVELY REDUCING VISIBILITY TO IFR CONDITIONS. IT WOULD NOT BE OUT OF THE QUESTION FOR VISIBILITY TO FALL BELOW 2SM OVERNIGHT AND SATURDAY WITHIN THE HEAVIER SNOW BANDS. RAISED VISIBILITY AT THE IWD TAF SITE FROM EARLIER THINKING AS SLEET MAY HELP TO KEEP VISIBILITY A BIT HIGHER. HIGH CLOUDS WILL START TO STREAM IN THIS AFTERNOON BEFORE DEEPER MOISTURE MOVES IN OVERNIGHT REDUCING CEILING HEIGHTS TO 1500FT OR LOWER THROUGH THE DAY SATURDAY. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 622 AM EDT FRI APR 5 2013 NW WINDS UP TO 25 KTS EARLY THIS MORNING OVER THE E HALF WILL DIMINISH STEADILY TODAY AS HI PRES IS FORECAST TO BUILD OVER UPR MI BY THIS AFTERNOON. LIGHT WINDS WILL SHIFT TO THE ESE AND INCREASE UP TO 20 KTS TONIGHT AS THE NEXT LO PRES SYSTEM IS FORECAST TO MOVE TO SW MN BY SAT MORNING. AS THE PRES GRADIENT TIGHTENS OVER LAKE SUP ON SAT/SAT NIGHT TO THE N OF THE LO TRACKING THRU THE CENTRAL LAKES... E-SE BACKING NE WINDS WILL INCREASE UP TO 25 TO 30 KTS BEFORE DIMINISHING AND FURTHER BACKING TO THE N ON SUN AS TRAILING HI PRES SHIFTS TOWARD THE UPPER LAKES. FOR EARLY NEXT WEEK...PLAN ON NE WINDS UP TO 20 KTS ON THE SE FLANK OF HI PRES OVER CENTRAL CANADA. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...JLA SHORT TERM...KC LONG TERM...VOSS AVIATION...KEC MARINE...KC
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1255 PM EDT FRI APR 5 2013 .UPDATE... ISSUED AT 1254 PM EDT FRI APR 5 2013 GIVEN LARGER SPRING STORM IS QUICKLY ON THE APPROACH...THOUGHT IT WOULD BE GOOD TO PROVIDE UPDATE IN TERMS OF EXPECTED STORM INTENSITY/PTYPE AND HEADLINES. SFC TROUGH THAT EVENTUALLY WILL DEVELOP INTO CLOSED OFF LOW OVER WESTERN LAKES LATER SATURDAY IS CURRENTLY ALLIGNED FROM SOUTHERN PORTIONS OF ALBERTA AND SASKATCHEWAN INTO NORTHERN US ROCKIES. 12Z RAOBS AND WV LOOP SHOW H5 TROUGH PUSHING OUT OF WA/OR...WHILE TROUGH AT H85 AND H7 IS CLOSER TO THE MAIN SFC LOW. SNOW IS AS CLOSE AS ND/SASKATCHEAN BORDER ON EDGE OF H8-H7 FRONTOGENESIS. NAM/GFS AND REGIONAL GEM INITIALIZED LARGER SCALE FEATURES WELL BUT DIFFER ON CRITICAL THERMAL DETAILS FOR SATURDAY. OVERALL...AT THE LEAST...WINTER WEATHER ADVISORIES WILL BE POSTED LATER THIS AFTN FOR ALL OF CWA. ALREADY COORD WITH DLH AND GRB WHICH HAVE ADVYS UP AND ALSO WITH APX. SOME AREAS MAY NEED WARNINGS BUT IT WILL DEPEND ON WHERE PTYPE REMAINS MOSTLY SNOW FOR THE EVENT. UNFORTUNATELY...THIS IS NOT CLEAR CUT EVEN WITHIN 24 HRS AS SOME MODELS /GFS AND UKMET/ ARE PRETTY WARM AT H85-H8 DURING THE AFTN HOURS ON SATURDAY /UP TO +3C AT H85/ WHILE NAM/REGIONAL GEM AND 00Z ECMWF ARE NOT AS WARM. THIS IS ESPECIALLY TOUGH CONSIDERING THEY ARE FAIRLY SIMILAR WITH H85/H7/H5 FEATURES. AS WOULD BE EXPECTED WITH THERMAL PROFILES...GFS/SREF ARE SLIGHTLY FARTHER NORTH WITH SFC LOW. GIVEN STEEP LAPSE RATES IN MID-LEVELS FEEDING INTO AREA OF PRECIPITATION OVER UPR MICHIGAN...THERE IS ALSO CONCERN CONVECTION WILL MODULATE INTENSITY AND PTYPE OVER THE CWA. AT THIS POINT...FAR SOUTH SEEMS PRETTY CERTAIN TO SEE MAINLY RAIN BY SATURDAY AFTN SO SNOW AMOUNTS WILL ULTIMATELY BE HELD DOWN FROM IMT TO ESC AND CERTAINLY SOUTH TO MNM. GOGEBIC AND IRON TOUGH CALL AS INITIAL WARM NOSE MAY RESULT IN MIX OF SLEET/SNOW AND EVEN RAIN LATE TONIGHT INTO SATURDAY MORNING BUT PRECIP WOULD TURN BACK TO MAINLY SNOW ON SATURDAY AFTN AS H7-H5 TROUGH/PRIMARY SHORTWAVES/LARGER SCALE LIFTING AND DYNAMIC COOLING ARRIVE. MUCH MORE OF A QUESTION IN THE TIER OF COUNTIES NORTH...FROM ONTONAGON/SOUTHERN HOUGHTON THROUGH BARARA/MARQUETTE AND EAST TO ALGER/SCHOOLCRAFT/LUCE COUNTY. IN THESE AREAS INITIAL SHOT OF PRECIP SATURDAY MORNING SHOULD REMAIN MOSTLY SNOW AS THINK THAT DYNAMIC COOLING TIED TO STRONG H8-H5 FGEN OFFSETS SHALLOW WARM LAYER H85-H8 AROUND +1C. INITIAL SURGE OF PRECIP DRIVEN BY 295-305K /H85-H5/ ISENTROPIC ASCENT AND DIVERGENCE ALOFT FROM LARGE JET STREAK OVER ONTARIO INTO QUEBEC COULD END AS MIX OF SLEET/SNOW AS DYNAMIC COOLING FADES BTWN 15Z-18Z. STILL MANY DETAILS TO BE SORTED OUT BUT WINTER WEATHER STATEMENT WITH FINAL HEADLINE DECISIONS WILL BE OUT LATER THIS AFTN. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 622 AM EDT FRI APR 5 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW CONFLUENT NW FLOW ALF OVER THE GRT LKS DOWNSTREAM OF RDG OVER THE ROCKIES. AT THE LLVLS...THE CWA IS DOMINATING BY A NW FLOW OF COLDER AIR IN THE WAKE OF THU COLD FROPA AND AHEAD OF SFC HI PRES NEAR LK WINNIPEG. SINCE THE 00Z INL RAOB SHOWED A VERY DRY...INVERTED V PROFILE AND RECENT SFC OBS INDICATE FAIRLY LARGE SFC T/TD SPREADS...SKIES ARE MOCLR OVER UPR MI AS OF 06Z. BUT THE 00Z YPL RAOB DEPICTED A SOMEWHAT MOISTER...BUT STILL WELL MIXED...SFC-H85 T/TD PROFILE WITH AN H85 TEMP DOWN TO -16C. FARTHER UPSTREAM...A SHRTWV IS MOVING INTO THE PAC NW. WAD MID/HI CLDS WELL E OF THIS DISTURBANCE ARE SPREADING INTO THE NRN PLAINS. TODAY...ALTHOUGH SKIES ARE MOCLR EARLY THIS MRNG...SUSPECT SOME LK CLDS/EVEN SOME -SHSN MIGHT DVLP OVER AREAS E OF MQT AS THE MOISTER...COLDER AIRMASS SHOWN ON THE 00Z YPL RAOB WITH H85 TEMPS AS LO AS -15C IMPACT THIS PART OF THE CWA. OVER THE W HALF...THE VERY DRY 00Z INL RAOB IS MORE REPRESENTATIVE OF THE SOURCE AIRMASS. SO REMOVED POPS/DIMINISHED FCST CLDS IN THIS AREA. BUT EVEN OVER THE E...GENERALY ACYC NATURE OF THE FCST LLVL FLOW AS WELL AS HIER SFC T/TD DEPRESSIONS EVEN FARTHER E N OF LK SUP SUG ANY SN ACCUMS WL BE NEGLIGIBLE IF SHSN DO FORM AT ALL. WITH DAYTIME HEATING/LARGE SCALE SUBSIDENCE AS SFC HI BLDS OVER THE W HALF OF THE CWA BY 18Z...EXPECT ANY LES OVER THE E TO DIMINISH BY NOON. DIURNAL CU/SC THAT DVLP WITH DAYTIME HEATING/MIXING UNDER LINGERING H85 THERMAL TROF WL TEND TO DIMINISH OVER AT LEAST THE W AND CENTRAL WITH MORE EMPHATIC DRYING/ QUICKER TRANSITION TO MORE ACYC FLOW...BUT SC MAY LINGER LONGER OVER THE E WHERE THE H85 TEMPS WARM ABV -10C ONLY TOWARD 00Z. MIXING TO H85 AS OBSVD ON UPSTREAM 00Z RAOBS YIELDS HI TEMPS IN THE UPR 30S/ LO 40S OVER THE W...BUT ONLY 30 TO 35 OVER THE CNTRL AND E WHERE LOWER H85 TEMPS LINGER LONGER. WITH WEAKER PRES GRADIENT ARRIVING WITH SFC HI CENTER...LK BREEZES WL MAINTAIN LOCAL COOLING NEAR THE SHORES. SOME HI CLDS WL ARRIVE OVER THE W IN THE AFTN WELL IN ADVANCE OF PAC NW SHRTWV MOVING THRU THE NRN ROCKIES. TNGT...AS SHRTWV MOVES THRU THE NRN PLAINS AND ASSOCIATED SFC LO SHIFTS TO SW MN BY 12Z SAT...EXPECT THICKENING CLDS IN THE DVLPG WAD PATTERN BTWN THE DEPARTING HI AND INCOMING LO PRES. VIGOROUS ISENTROPIC ASCENT SHOWN ON THE 280-295K ISENTROPIC SFCS IS FCST TO SPREAD W-E ACRS THE CWA AND SLOWLY SATURATE THE VERY DRY ANTECEDENT LO-MID LVLS. FAVOR THE SOMEWHAT SLOWER 00Z NAM/CNDN AND 12Z ECMWF FOR TIMING LEADING EDGE OF PCPN TIED TO H5-7 FGEN AXIS OVER THE GFS...WHICH APPEARS TO GENERATE PCPN TOO DEEP INTO THE LINGERING DRY AIR. THESE FAVORED MODELS INDICATE PCPN WL REACH A LINE FROM MUNISING-MANISTIQUE BY 12Z SAT... SO RESTRICTED CATEGORICAL POPS TO THE W OF THAT AXIS. FAVORED MODEL QPF INDICATES 2 TO 3 INCHES OF SN OVER THE SW CWA BY 12Z SAT EVEN THOUGH RATHER NARROW/HI DGZ CENTERED ARND 15K FT WL LIMIT SN/WATER RATIOS. EXPECT THE LOWEST MIN TEMPS OVER THE INTERIOR E...WHERE THE CLDS WL ARRIVE LATEST AND WINDS BE LGT IN THE EVNG TO ALLOW FOR GOOD RADIATIONAL COOLING. FOLLOWED A NON-DIURNAL CURVE WITH TEMPS FALLING TO THE LOWEST LVL FAIRLY EARLY...THEN STEADY OR SLOWLY RISING. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 622 AM EDT FRI APR 5 2013 MAIN FCST CONCERNS FOCUS ON SYSTEM FOR SATURDAY...PTYPE CONCERNS...POSSIBLE HEADLINES AND SNOW AMTS. ACTIVE SHORTWAVE NOW MOVING IN OFF THE PACIFIC NW AS NOTED ON WATER VAPOR LOOP IS EXPECTED TO TRACK DUE E...REACHING THE WRN GREAT LAKES SAT. WHILE MODELS HAVE COME INTO BETTER AGREEMENT WITH TRACK/TIMING OF SHORTWAVE AND ASSOC SFC LOW SOME IMPORTANT MODEL DIFFERENCES REMAIN IN THERMAL FIELDS. CONFIDENCE IS HIGH THAT ALL OF THE FCST AREA WILL SEE PCPN...SO HIGH CATEGORICAL POPS WILL BE PAINTED ACROSS THE CWA. RIGHT ENTRANCE OF UPPER JET ASSOCIATED WITH ERN CANADA TROF WILL PROVIDE LARGER SCALE ENHANCEMENT TO UPWARD MOTION...AS A FAIRLY VIGOROUS FRONTOGENESIS SIGNATURE WILL AID PCPN INTENSITY ON THE SMALLER SCALE. IT APPEARS THAT THERE MAY BE 2 PERIODS OF FGEN FORCING...ONE INITIALLY LATE TONIGHT/SAT MORNING THAT TRANSLATES ACROSS THE AREA...THEN A SECOND SAT AFTN/EVENING THAT WOULD FAVOR CNTRL/ERN UPPER MI FOR HEAVIER PCPN. WITH MIXING RATIOS OF 4-5G/KG AND CLOSE TO 12HRS OF ASCENT...THERE COULD BE 6 TO POSSIBLY AS MUCH AS LOCALLY 8-10 INCHES OF HVY/WET SNOW ALONG THE AXIS OF HEAVIEST PCPN WHERE PTYPE IS ALL SNOW. SO...DETERMINING THE CONFIGURATION OF PTYPES WILL BE CRITICAL. IS STILL APPEARS THAT PTYPE WILL BE ALL SNOW ACROSS THE FCST AREA AS PCPN DEVELOPS TONIGHT ...AND THAT SNOW MAY FALL LONG ENOUGH SO THAT A FEW INCHES OF SNOW ACCUMULATE EVEN IN AREAS THAT SEE A MIX OR CHANGE TO RAIN DURING THE DAY SAT. DURING THE DAY SAT...UNCERTAINTY GROWS IN HOW FAR N WARMING OCCURS. THE 06Z GFS AND NAM BRINGS 0C 850MB ISOTHERM AND CRITICAL 1000-850MB THICKNESS FAR ENOUGH N SO THAT PERHAPS ONLY WEST AND NW UPPER MI REMAINS MOSTLY SNOW SAT AFTN/EVENING. THE LOCAL WRF-ARW AND REG-GEM ARE FARTHER S WITH THESE TEMP PARAMETERS AND ARE GENERALLY MORE IN LINE WITH THE ECMWF...SUGGESTING MUCH OF NRN UPPER MI WILL STAY MOSTLY SNOW. FCST SOUNDINGS STILL SUGGEST THAT A NARROW ZONE OF SLEET IS ALSO POSSIBLE IN THE TRANSITION ZONE BTWN MOSTLY SNOW NORTH TO MOSTLY RAIN SOUTH ON SAT. CONSIDERED ISSUING A WATCH FOR SOME THE NRN COUNTIES IN SWATH OF EXPECTED HEAVIER PCPN WHERE PTYPE WILL BE MOSTLY SNOW...BUT GIVEN CONTINUED UNCERTAINTIES WITH PTYPE AND ULTIMATE ACCUMS DECIDED TO KEEP AN SPS GOING HIGHLIGHTING THE POTENTIAL FOR VERY HVY/WET SNOW THAT WILL BE DIFFICULT TO SHOVEL/PLOW AND WILL LEAD TO VERY DIFFICULT TRAVEL CONDITIONS. ON SUN...SFC HIGH PRES WILL NOSE INTO THE UPPER LAKES BEHIND SYSTEM...BRINGING AN INFLUX OF DRIER AIR. DAYTIME TEMPS SHOULD RECOVER WELL INTO THE 30S/LWR 40S IN THE AFTN WITH SOME INCREASE IN SUNSHINE DURING THE DAY. FCST FOR MON THRU THU REMAINS UNCERTAIN. MUCH OF THE FCST WILL HINGE ON THE STRENGTH OF THE LINGERING ERN CANADA TROF UNDER THE WEAKENING NEGATIVE AO/NAO PATTERN. OTHER THAN A SHOWING A WEAK NRN PLAINS SHORTWAVE MOVING THROUGH THE AREA LATE SUNDAY NIGHT INTO MONDAY...THE LATEST ECMWF IS SIMILAR TO RECENT RUNS SHOWING A STRONGER AND MORE PERSISTENT ERN CANADIAN TROF WHICH KEEPS A DRIER WNW FLOW ACROSS THE UPPER LAKES FOR THE EARLY PART OF NEXT WEEK. THIS IDEA ALSO WOULD GO ALONG WITH THE GENERAL PERSISTENT PATTERN WHICH HAS DOMINATED THE REGION FOR THE LAST SEVERAL WEEKS...ALTHOUGH IT REMAINS TO BE SEEN HOW LONG PATTERN WILL PERSIST GIVEN EXPECT WEAKENING OF HIGH LATITUDE BLOCKING. THE 12Z ECMWF DOES FINALLY BRING PCPN INTO THE FCST AREA ON WED NIGHT AND THU...MAINLY IN FORM OF SNOW...AS MAIN PIECE OF ENERGY FROM WRN CONUS TROF EJECTS NE TOWARD THE GREAT LAKES. MEANWHILE...THE LATEST 00Z RUN OF THE GFS QUICKLY WEAKENS THE ERN CANADIAN TROF AND PUSHES IT EAST ALLOWING FOR A STRONG SRN STREAM SHORTWAVE TO EJECT TOWARD THE UPPER GREAT LAKES FM BASE OF WRN CONUS TROF. THE GFS SHOWS 8H TEMPS RISING TO 10-12C BY TUE NIGHT INTO WED ACCOMPANIED BY A SLUG OF GULF MOISTURE (250-300 PCT OF NORMAL PWAT VALUES) WHICH WOULD YIELD A THREAT OF MODERATE TO HEAVY RAIN TO THE FCST AREA TUE NIGHT INTO WED. THE 12Z GEM-NH GENERALLY LENDS MORE SUPPORT TO ECMWF SOLN ALTHOUGH IT ALSO TENDS TO BREAK DOWN ERN CANADIAN TROF QUICKER THAN ECMWF. GIVEN CONSIDERABLE MODEL UNCERTAINTY...WILL CONTINUE SIMPLE CONSENSUS APPROACH TO FCST KEEPING ONLY SCHC POPS FOR MON INTO TUE THEN INCREASE POPS TO 30-40 PCT CHC FOR WED AND THU WITH THE IDEA THAT ERN CANADA TROF WILL WEAKEN ALLOWING FOR MORE ENERGY FROM WRN CONUS TROF TO REACH UPPER GREAT LAKES. TEMPS SHOULD REMAIN BLO NORMAL THRU THE PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 732 AM EDT FRI APR 5 2013 ALTHOUGH THERE WL BE SOME SC AT MAINLY SAW INTO THIS AFTN...DRY NATURE OF THE INCOMING AIRMASS ASSOCIATED WITH HI PRES MOVING INTO MN WL BRING VFR CONDITIONS AT ALL 3 LOCATIONS INTO THIS EVNG. THICKER CLDS AND THEN SN WL ARRIVE TNGT IN ADVANCE OF A LO PRES SYSTEM MOVING THRU THE NRN PLAINS. EVEN BEFORE THE SN ARRIVES...CIGS AT SAW MAY FALL INTO THE MVFR RANGE WITH UPSLOPE SE FLOW BTWN THE DEPARTING HI/INCOMING LO PRES. EXPECT VSBYS TO DROP INTO THE IFR CATEGORY AT ALL 3 LOCATIONS AFTER MIDNGT. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 622 AM EDT FRI APR 5 2013 NW WINDS UP TO 25 KTS EARLY THIS MORNING OVER THE E HALF WILL DIMINISH STEADILY TODAY AS HI PRES IS FORECAST TO BUILD OVER UPR MI BY THIS AFTERNOON. LIGHT WINDS WILL SHIFT TO THE ESE AND INCREASE UP TO 20 KTS TONIGHT AS THE NEXT LO PRES SYSTEM IS FORECAST TO MOVE TO SW MN BY SAT MORNING. AS THE PRES GRADIENT TIGHTENS OVER LAKE SUP ON SAT/SAT NIGHT TO THE N OF THE LO TRACKING THRU THE CENTRAL LAKES... E-SE BACKING NE WINDS WILL INCREASE UP TO 25 TO 30 KTS BEFORE DIMINISHING AND FURTHER BACKING TO THE N ON SUN AS TRAILING HI PRES SHIFTS TOWARD THE UPPER LAKES. FOR EARLY NEXT WEEK...PLAN ON NE WINDS UP TO 20 KTS ON THE SE FLANK OF HI PRES OVER CENTRAL CANADA. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...JLA SHORT TERM...KC LONG TERM...VOSS AVIATION...KC MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
732 AM EDT FRI APR 5 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 622 AM EDT FRI APR 5 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW CONFLUENT NW FLOW ALF OVER THE GRT LKS DOWNSTREAM OF RDG OVER THE ROCKIES. AT THE LLVLS...THE CWA IS DOMINATING BY A NW FLOW OF COLDER AIR IN THE WAKE OF THU COLD FROPA AND AHEAD OF SFC HI PRES NEAR LK WINNIPEG. SINCE THE 00Z INL RAOB SHOWED A VERY DRY...INVERTED V PROFILE AND RECENT SFC OBS INDICATE FAIRLY LARGE SFC T/TD SPREADS...SKIES ARE MOCLR OVER UPR MI AS OF 06Z. BUT THE 00Z YPL RAOB DEPICTED A SOMEWHAT MOISTER...BUT STILL WELL MIXED...SFC-H85 T/TD PROFILE WITH AN H85 TEMP DOWN TO -16C. FARTHER UPSTREAM...A SHRTWV IS MOVING INTO THE PAC NW. WAD MID/HI CLDS WELL E OF THIS DISTURBANCE ARE SPREADING INTO THE NRN PLAINS. TODAY...ALTHOUGH SKIES ARE MOCLR EARLY THIS MRNG...SUSPECT SOME LK CLDS/EVEN SOME -SHSN MIGHT DVLP OVER AREAS E OF MQT AS THE MOISTER...COLDER AIRMASS SHOWN ON THE 00Z YPL RAOB WITH H85 TEMPS AS LO AS -15C IMPACT THIS PART OF THE CWA. OVER THE W HALF...THE VERY DRY 00Z INL RAOB IS MORE REPRESENTATIVE OF THE SOURCE AIRMASS. SO REMOVED POPS/DIMINISHED FCST CLDS IN THIS AREA. BUT EVEN OVER THE E...GENERALY ACYC NATURE OF THE FCST LLVL FLOW AS WELL AS HIER SFC T/TD DEPRESSIONS EVEN FARTHER E N OF LK SUP SUG ANY SN ACCUMS WL BE NEGLIGIBLE IF SHSN DO FORM AT ALL. WITH DAYTIME HEATING/LARGE SCALE SUBSIDENCE AS SFC HI BLDS OVER THE W HALF OF THE CWA BY 18Z...EXPECT ANY LES OVER THE E TO DIMINISH BY NOON. DIURNAL CU/SC THAT DVLP WITH DAYTIME HEATING/MIXING UNDER LINGERING H85 THERMAL TROF WL TEND TO DIMINISH OVER AT LEAST THE W AND CENTRAL WITH MORE EMPHATIC DRYING/ QUICKER TRANSITION TO MORE ACYC FLOW...BUT SC MAY LINGER LONGER OVER THE E WHERE THE H85 TEMPS WARM ABV -10C ONLY TOWARD 00Z. MIXING TO H85 AS OBSVD ON UPSTREAM 00Z RAOBS YIELDS HI TEMPS IN THE UPR 30S/ LO 40S OVER THE W...BUT ONLY 30 TO 35 OVER THE CNTRL AND E WHERE LOWER H85 TEMPS LINGER LONGER. WITH WEAKER PRES GRADIENT ARRIVING WITH SFC HI CENTER...LK BREEZES WL MAINTAIN LOCAL COOLING NEAR THE SHORES. SOME HI CLDS WL ARRIVE OVER THE W IN THE AFTN WELL IN ADVANCE OF PAC NW SHRTWV MOVING THRU THE NRN ROCKIES. TNGT...AS SHRTWV MOVES THRU THE NRN PLAINS AND ASSOCIATED SFC LO SHIFTS TO SW MN BY 12Z SAT...EXPECT THICKENING CLDS IN THE DVLPG WAD PATTERN BTWN THE DEPARTING HI AND INCOMING LO PRES. VIGOROUS ISENTROPIC ASCENT SHOWN ON THE 280-295K ISENTROPIC SFCS IS FCST TO SPREAD W-E ACRS THE CWA AND SLOWLY SATURATE THE VERY DRY ANTECEDENT LO-MID LVLS. FAVOR THE SOMEWHAT SLOWER 00Z NAM/CNDN AND 12Z ECMWF FOR TIMING LEADING EDGE OF PCPN TIED TO H5-7 FGEN AXIS OVER THE GFS...WHICH APPEARS TO GENERATE PCPN TOO DEEP INTO THE LINGERING DRY AIR. THESE FAVORED MODELS INDICATE PCPN WL REACH A LINE FROM MUNISING-MANISTIQUE BY 12Z SAT... SO RESTRICTED CATEGORICAL POPS TO THE W OF THAT AXIS. FAVORED MODEL QPF INDICATES 2 TO 3 INCHES OF SN OVER THE SW CWA BY 12Z SAT EVEN THOUGH RATHER NARROW/HI DGZ CENTERED ARND 15K FT WL LIMIT SN/WATER RATIOS. EXPECT THE LOWEST MIN TEMPS OVER THE INTERIOR E...WHERE THE CLDS WL ARRIVE LATEST AND WINDS BE LGT IN THE EVNG TO ALLOW FOR GOOD RADIATIONAL COOLING. FOLLOWED A NON-DIURNAL CURVE WITH TEMPS FALLING TO THE LOWEST LVL FAIRLY EARLY...THEN STEADY OR SLOWLY RISING. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 622 AM EDT FRI APR 5 2013 MAIN FCST CONCERNS FOCUS ON SYSTEM FOR SATURDAY...PTYPE CONCERNS...POSSIBLE HEADLINES AND SNOW AMTS. ACTIVE SHORTWAVE NOW MOVING IN OFF THE PACIFIC NW AS NOTED ON WATER VAPOR LOOP IS EXPECTED TO TRACK DUE E...REACHING THE WRN GREAT LAKES SAT. WHILE MODELS HAVE COME INTO BETTER AGREEMENT WITH TRACK/TIMING OF SHORTWAVE AND ASSOC SFC LOW SOME IMPORTANT MODEL DIFFERENCES REMAIN IN THERMAL FIELDS. CONFIDENCE IS HIGH THAT ALL OF THE FCST AREA WILL SEE PCPN...SO HIGH CATEGORICAL POPS WILL BE PAINTED ACROSS THE CWA. RIGHT ENTRANCE OF UPPER JET ASSOCIATED WITH ERN CANADA TROF WILL PROVIDE LARGER SCALE ENHANCEMENT TO UPWARD MOTION...AS A FAIRLY VIGOROUS FRONTOGENESIS SIGNATURE WILL AID PCPN INTENSITY ON THE SMALLER SCALE. IT APPEARS THAT THERE MAY BE 2 PERIODS OF FGEN FORCING...ONE INITIALLY LATE TONIGHT/SAT MORNING THAT TRANSLATES ACROSS THE AREA...THEN A SECOND SAT AFTN/EVENING THAT WOULD FAVOR CNTRL/ERN UPPER MI FOR HEAVIER PCPN. WITH MIXING RATIOS OF 4-5G/KG AND CLOSE TO 12HRS OF ASCENT...THERE COULD BE 6 TO POSSIBLY AS MUCH AS LOCALLY 8-10 INCHES OF HVY/WET SNOW ALONG THE AXIS OF HEAVIEST PCPN WHERE PTYPE IS ALL SNOW. SO...DETERMINING THE CONFIGURATION OF PTYPES WILL BE CRITICAL. IS STILL APPEARS THAT PTYPE WILL BE ALL SNOW ACROSS THE FCST AREA AS PCPN DEVELOPS TONIGHT ...AND THAT SNOW MAY FALL LONG ENOUGH SO THAT A FEW INCHES OF SNOW ACCUMULATE EVEN IN AREAS THAT SEE A MIX OR CHANGE TO RAIN DURING THE DAY SAT. DURING THE DAY SAT...UNCERTAINTY GROWS IN HOW FAR N WARMING OCCURS. THE 06Z GFS AND NAM BRINGS 0C 850MB ISOTHERM AND CRITICAL 1000-850MB THICKNESS FAR ENOUGH N SO THAT PERHAPS ONLY WEST AND NW UPPER MI REMAINS MOSTLY SNOW SAT AFTN/EVENING. THE LOCAL WRF-ARW AND REG-GEM ARE FARTHER S WITH THESE TEMP PARAMETERS AND ARE GENERALLY MORE IN LINE WITH THE ECMWF...SUGGESTING MUCH OF NRN UPPER MI WILL STAY MOSTLY SNOW. FCST SOUNDINGS STILL SUGGEST THAT A NARROW ZONE OF SLEET IS ALSO POSSIBLE IN THE TRANSITION ZONE BTWN MOSTLY SNOW NORTH TO MOSTLY RAIN SOUTH ON SAT. CONSIDERED ISSUING A WATCH FOR SOME THE NRN COUNTIES IN SWATH OF EXPECTED HEAVIER PCPN WHERE PTYPE WILL BE MOSTLY SNOW...BUT GIVEN CONTINUED UNCERTAINTIES WITH PTYPE AND ULTIMATE ACCUMS DECIDED TO KEEP AN SPS GOING HIGHLIGHTING THE POTENTIAL FOR VERY HVY/WET SNOW THAT WILL BE DIFFICULT TO SHOVEL/PLOW AND WILL LEAD TO VERY DIFFICULT TRAVEL CONDITIONS. ON SUN...SFC HIGH PRES WILL NOSE INTO THE UPPER LAKES BEHIND SYSTEM...BRINGING AN INFLUX OF DRIER AIR. DAYTIME TEMPS SHOULD RECOVER WELL INTO THE 30S/LWR 40S IN THE AFTN WITH SOME INCREASE IN SUNSHINE DURING THE DAY. FCST FOR MON THRU THU REMAINS UNCERTAIN. MUCH OF THE FCST WILL HINGE ON THE STRENGTH OF THE LINGERING ERN CANADA TROF UNDER THE WEAKENING NEGATIVE AO/NAO PATTERN. OTHER THAN A SHOWING A WEAK NRN PLAINS SHORTWAVE MOVING THROUGH THE AREA LATE SUNDAY NIGHT INTO MONDAY...THE LATEST ECMWF IS SIMILAR TO RECENT RUNS SHOWING A STRONGER AND MORE PERSISTENT ERN CANADIAN TROF WHICH KEEPS A DRIER WNW FLOW ACROSS THE UPPER LAKES FOR THE EARLY PART OF NEXT WEEK. THIS IDEA ALSO WOULD GO ALONG WITH THE GENERAL PERSISTENT PATTERN WHICH HAS DOMINATED THE REGION FOR THE LAST SEVERAL WEEKS...ALTHOUGH IT REMAINS TO BE SEEN HOW LONG PATTERN WILL PERSIST GIVEN EXPECT WEAKENING OF HIGH LATITUDE BLOCKING. THE 12Z ECMWF DOES FINALLY BRING PCPN INTO THE FCST AREA ON WED NIGHT AND THU...MAINLY IN FORM OF SNOW...AS MAIN PIECE OF ENERGY FROM WRN CONUS TROF EJECTS NE TOWARD THE GREAT LAKES. MEANWHILE...THE LATEST 00Z RUN OF THE GFS QUICKLY WEAKENS THE ERN CANADIAN TROF AND PUSHES IT EAST ALLOWING FOR A STRONG SRN STREAM SHORTWAVE TO EJECT TOWARD THE UPPER GREAT LAKES FM BASE OF WRN CONUS TROF. THE GFS SHOWS 8H TEMPS RISING TO 10-12C BY TUE NIGHT INTO WED ACCOMPANIED BY A SLUG OF GULF MOISTURE (250-300 PCT OF NORMAL PWAT VALUES) WHICH WOULD YIELD A THREAT OF MODERATE TO HEAVY RAIN TO THE FCST AREA TUE NIGHT INTO WED. THE 12Z GEM-NH GENERALLY LENDS MORE SUPPORT TO ECMWF SOLN ALTHOUGH IT ALSO TENDS TO BREAK DOWN ERN CANADIAN TROF QUICKER THAN ECMWF. GIVEN CONSIDERABLE MODEL UNCERTAINTY...WILL CONTINUE SIMPLE CONSENSUS APPROACH TO FCST KEEPING ONLY SCHC POPS FOR MON INTO TUE THEN INCREASE POPS TO 30-40 PCT CHC FOR WED AND THU WITH THE IDEA THAT ERN CANADA TROF WILL WEAKEN ALLOWING FOR MORE ENERGY FROM WRN CONUS TROF TO REACH UPPER GREAT LAKES. TEMPS SHOULD REMAIN BLO NORMAL THRU THE PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 732 AM EDT FRI APR 5 2013 ALTHOUGH THERE WL BE SOME SC AT MAINLY SAW INTO THIS AFTN...DRY NATURE OF THE INCOMING AIRMASS ASSOCIATED WITH HI PRES MOVING INTO MN WL BRING VFR CONDITIONS AT ALL 3 LOCATIONS INTO THIS EVNG. THICKER CLDS AND THEN SN WL ARRIVE TNGT IN ADVANCE OF A LO PRES SYSTEM MOVING THRU THE NRN PLAINS. EVEN BEFORE THE SN ARRIVES...CIGS AT SAW MAY FALL INTO THE MVFR RANGE WITH UPSLOPE SE FLOW BTWN THE DEPARTING HI/INCOMING LO PRES. EXPECT VSBYS TO DROP INTO THE IFR CATEGORY AT ALL 3 LOCATIONS AFTER MIDNGT. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 622 AM EDT FRI APR 5 2013 NW WINDS UP TO 25 KTS EARLY THIS MORNING OVER THE E HALF WILL DIMINISH STEADILY TODAY AS HI PRES IS FORECAST TO BUILD OVER UPR MI BY THIS AFTERNOON. LIGHT WINDS WILL SHIFT TO THE ESE AND INCREASE UP TO 20 KTS TONIGHT AS THE NEXT LO PRES SYSTEM IS FORECAST TO MOVE TO SW MN BY SAT MORNING. AS THE PRES GRADIENT TIGHTENS OVER LAKE SUP ON SAT/SAT NIGHT TO THE N OF THE LO TRACKING THRU THE CENTRAL LAKES... E-SE BACKING NE WINDS WILL INCREASE UP TO 25 TO 30 KTS BEFORE DIMINISHING AND FURTHER BACKING TO THE N ON SUN AS TRAILING HI PRES SHIFTS TOWARD THE UPPER LAKES. FOR EARLY NEXT WEEK...PLAN ON NE WINDS UP TO 20 KTS ON THE SE FLANK OF HI PRES OVER CENTRAL CANADA. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...VOSS AVIATION...KC MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
624 AM EDT FRI APR 5 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 622 AM EDT FRI APR 5 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW CONFLUENT NW FLOW ALF OVER THE GRT LKS DOWNSTREAM OF RDG OVER THE ROCKIES. AT THE LLVLS...THE CWA IS DOMINATING BY A NW FLOW OF COLDER AIR IN THE WAKE OF THU COLD FROPA AND AHEAD OF SFC HI PRES NEAR LK WINNIPEG. SINCE THE 00Z INL RAOB SHOWED A VERY DRY...INVERTED V PROFILE AND RECENT SFC OBS INDICATE FAIRLY LARGE SFC T/TD SPREADS...SKIES ARE MOCLR OVER UPR MI AS OF 06Z. BUT THE 00Z YPL RAOB DEPICTED A SOMEWHAT MOISTER...BUT STILL WELL MIXED...SFC-H85 T/TD PROFILE WITH AN H85 TEMP DOWN TO -16C. FARTHER UPSTREAM...A SHRTWV IS MOVING INTO THE PAC NW. WAD MID/HI CLDS WELL E OF THIS DISTURBANCE ARE SPREADING INTO THE NRN PLAINS. TODAY...ALTHOUGH SKIES ARE MOCLR EARLY THIS MRNG...SUSPECT SOME LK CLDS/EVEN SOME -SHSN MIGHT DVLP OVER AREAS E OF MQT AS THE MOISTER...COLDER AIRMASS SHOWN ON THE 00Z YPL RAOB WITH H85 TEMPS AS LO AS -15C IMPACT THIS PART OF THE CWA. OVER THE W HALF...THE VERY DRY 00Z INL RAOB IS MORE REPRESENTATIVE OF THE SOURCE AIRMASS. SO REMOVED POPS/DIMINISHED FCST CLDS IN THIS AREA. BUT EVEN OVER THE E...GENERALY ACYC NATURE OF THE FCST LLVL FLOW AS WELL AS HIER SFC T/TD DEPRESSIONS EVEN FARTHER E N OF LK SUP SUG ANY SN ACCUMS WL BE NEGLIGIBLE IF SHSN DO FORM AT ALL. WITH DAYTIME HEATING/LARGE SCALE SUBSIDENCE AS SFC HI BLDS OVER THE W HALF OF THE CWA BY 18Z...EXPECT ANY LES OVER THE E TO DIMINISH BY NOON. DIURNAL CU/SC THAT DVLP WITH DAYTIME HEATING/MIXING UNDER LINGERING H85 THERMAL TROF WL TEND TO DIMINISH OVER AT LEAST THE W AND CENTRAL WITH MORE EMPHATIC DRYING/ QUICKER TRANSITION TO MORE ACYC FLOW...BUT SC MAY LINGER LONGER OVER THE E WHERE THE H85 TEMPS WARM ABV -10C ONLY TOWARD 00Z. MIXING TO H85 AS OBSVD ON UPSTREAM 00Z RAOBS YIELDS HI TEMPS IN THE UPR 30S/ LO 40S OVER THE W...BUT ONLY 30 TO 35 OVER THE CNTRL AND E WHERE LOWER H85 TEMPS LINGER LONGER. WITH WEAKER PRES GRADIENT ARRIVING WITH SFC HI CENTER...LK BREEZES WL MAINTAIN LOCAL COOLING NEAR THE SHORES. SOME HI CLDS WL ARRIVE OVER THE W IN THE AFTN WELL IN ADVANCE OF PAC NW SHRTWV MOVING THRU THE NRN ROCKIES. TNGT...AS SHRTWV MOVES THRU THE NRN PLAINS AND ASSOCIATED SFC LO SHIFTS TO SW MN BY 12Z SAT...EXPECT THICKENING CLDS IN THE DVLPG WAD PATTERN BTWN THE DEPARTING HI AND INCOMING LO PRES. VIGOROUS ISENTROPIC ASCENT SHOWN ON THE 280-295K ISENTROPIC SFCS IS FCST TO SPREAD W-E ACRS THE CWA AND SLOWLY SATURATE THE VERY DRY ANTECEDENT LO-MID LVLS. FAVOR THE SOMEWHAT SLOWER 00Z NAM/CNDN AND 12Z ECMWF FOR TIMING LEADING EDGE OF PCPN TIED TO H5-7 FGEN AXIS OVER THE GFS...WHICH APPEARS TO GENERATE PCPN TOO DEEP INTO THE LINGERING DRY AIR. THESE FAVORED MODELS INDICATE PCPN WL REACH A LINE FROM MUNISING-MANISTIQUE BY 12Z SAT... SO RESTRICTED CATEGORICAL POPS TO THE W OF THAT AXIS. FAVORED MODEL QPF INDICATES 2 TO 3 INCHES OF SN OVER THE SW CWA BY 12Z SAT EVEN THOUGH RATHER NARROW/HI DGZ CENTERED ARND 15K FT WL LIMIT SN/WATER RATIOS. EXPECT THE LOWEST MIN TEMPS OVER THE INTERIOR E...WHERE THE CLDS WL ARRIVE LATEST AND WINDS BE LGT IN THE EVNG TO ALLOW FOR GOOD RADIATIONAL COOLING. FOLLOWED A NON-DIURNAL CURVE WITH TEMPS FALLING TO THE LOWEST LVL FAIRLY EARLY...THEN STEADY OR SLOWLY RISING. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 622 AM EDT FRI APR 5 2013 MAIN FCST CONCERNS FOCUS ON SYSTEM FOR SATURDAY...PTYPE CONCERNS...POSSIBLE HEADLINES AND SNOW AMTS. ACTIVE SHORTWAVE NOW MOVING IN OFF THE PACIFIC NW AS NOTED ON WATER VAPOR LOOP IS EXPECTED TO TRACK DUE E...REACHING THE WRN GREAT LAKES SAT. WHILE MODELS HAVE COME INTO BETTER AGREEMENT WITH TRACK/TIMING OF SHORTWAVE AND ASSOC SFC LOW SOME IMPORTANT MODEL DIFFERENCES REMAIN IN THERMAL FIELDS. CONFIDENCE IS HIGH THAT ALL OF THE FCST AREA WILL SEE PCPN...SO HIGH CATEGORICAL POPS WILL BE PAINTED ACROSS THE CWA. RIGHT ENTRANCE OF UPPER JET ASSOCIATED WITH ERN CANADA TROF WILL PROVIDE LARGER SCALE ENHANCEMENT TO UPWARD MOTION...AS A FAIRLY VIGOROUS FRONTOGENESIS SIGNATURE WILL AID PCPN INTENSITY ON THE SMALLER SCALE. IT APPEARS THAT THERE MAY BE 2 PERIODS OF FGEN FORCING...ONE INITIALLY LATE TONIGHT/SAT MORNING THAT TRANSLATES ACROSS THE AREA...THEN A SECOND SAT AFTN/EVENING THAT WOULD FAVOR CNTRL/ERN UPPER MI FOR HEAVIER PCPN. WITH MIXING RATIOS OF 4-5G/KG AND CLOSE TO 12HRS OF ASCENT...THERE COULD BE 6 TO POSSIBLY AS MUCH AS LOCALLY 8-10 INCHES OF HVY/WET SNOW ALONG THE AXIS OF HEAVIEST PCPN WHERE PTYPE IS ALL SNOW. SO...DETERMINING THE CONFIGURATION OF PTYPES WILL BE CRITICAL. IS STILL APPEARS THAT PTYPE WILL BE ALL SNOW ACROSS THE FCST AREA AS PCPN DEVELOPS TONIGHT ...AND THAT SNOW MAY FALL LONG ENOUGH SO THAT A FEW INCHES OF SNOW ACCUMULATE EVEN IN AREAS THAT SEE A MIX OR CHANGE TO RAIN DURING THE DAY SAT. DURING THE DAY SAT...UNCERTAINTY GROWS IN HOW FAR N WARMING OCCURS. THE 06Z GFS AND NAM BRINGS 0C 850MB ISOTHERM AND CRITICAL 1000-850MB THICKNESS FAR ENOUGH N SO THAT PERHAPS ONLY WEST AND NW UPPER MI REMAINS MOSTLY SNOW SAT AFTN/EVENING. THE LOCAL WRF-ARW AND REG-GEM ARE FARTHER S WITH THESE TEMP PARAMETERS AND ARE GENERALLY MORE IN LINE WITH THE ECMWF...SUGGESTING MUCH OF NRN UPPER MI WILL STAY MOSTLY SNOW. FCST SOUNDINGS STILL SUGGEST THAT A NARROW ZONE OF SLEET IS ALSO POSSIBLE IN THE TRANSITION ZONE BTWN MOSTLY SNOW NORTH TO MOSTLY RAIN SOUTH ON SAT. CONSIDERED ISSUING A WATCH FOR SOME THE NRN COUNTIES IN SWATH OF EXPECTED HEAVIER PCPN WHERE PTYPE WILL BE MOSTLY SNOW...BUT GIVEN CONTINUED UNCERTAINTIES WITH PTYPE AND ULTIMATE ACCUMS DECIDED TO KEEP AN SPS GOING HIGHLIGHTING THE POTENTIAL FOR VERY HVY/WET SNOW THAT WILL BE DIFFICULT TO SHOVEL/PLOW AND WILL LEAD TO VERY DIFFICULT TRAVEL CONDITIONS. ON SUN...SFC HIGH PRES WILL NOSE INTO THE UPPER LAKES BEHIND SYSTEM...BRINGING AN INFLUX OF DRIER AIR. DAYTIME TEMPS SHOULD RECOVER WELL INTO THE 30S/LWR 40S IN THE AFTN WITH SOME INCREASE IN SUNSHINE DURING THE DAY. FCST FOR MON THRU THU REMAINS UNCERTAIN. MUCH OF THE FCST WILL HINGE ON THE STRENGTH OF THE LINGERING ERN CANADA TROF UNDER THE WEAKENING NEGATIVE AO/NAO PATTERN. OTHER THAN A SHOWING A WEAK NRN PLAINS SHORTWAVE MOVING THROUGH THE AREA LATE SUNDAY NIGHT INTO MONDAY...THE LATEST ECMWF IS SIMILAR TO RECENT RUNS SHOWING A STRONGER AND MORE PERSISTENT ERN CANADIAN TROF WHICH KEEPS A DRIER WNW FLOW ACROSS THE UPPER LAKES FOR THE EARLY PART OF NEXT WEEK. THIS IDEA ALSO WOULD GO ALONG WITH THE GENERAL PERSISTENT PATTERN WHICH HAS DOMINATED THE REGION FOR THE LAST SEVERAL WEEKS...ALTHOUGH IT REMAINS TO BE SEEN HOW LONG PATTERN WILL PERSIST GIVEN EXPECT WEAKENING OF HIGH LATITUDE BLOCKING. THE 12Z ECMWF DOES FINALLY BRING PCPN INTO THE FCST AREA ON WED NIGHT AND THU...MAINLY IN FORM OF SNOW...AS MAIN PIECE OF ENERGY FROM WRN CONUS TROF EJECTS NE TOWARD THE GREAT LAKES. MEANWHILE...THE LATEST 00Z RUN OF THE GFS QUICKLY WEAKENS THE ERN CANADIAN TROF AND PUSHES IT EAST ALLOWING FOR A STRONG SRN STREAM SHORTWAVE TO EJECT TOWARD THE UPPER GREAT LAKES FM BASE OF WRN CONUS TROF. THE GFS SHOWS 8H TEMPS RISING TO 10-12C BY TUE NIGHT INTO WED ACCOMPANIED BY A SLUG OF GULF MOISTURE (250-300 PCT OF NORMAL PWAT VALUES) WHICH WOULD YIELD A THREAT OF MODERATE TO HEAVY RAIN TO THE FCST AREA TUE NIGHT INTO WED. THE 12Z GEM-NH GENERALLY LENDS MORE SUPPORT TO ECMWF SOLN ALTHOUGH IT ALSO TENDS TO BREAK DOWN ERN CANADIAN TROF QUICKER THAN ECMWF. GIVEN CONSIDERABLE MODEL UNCERTAINTY...WILL CONTINUE SIMPLE CONSENSUS APPROACH TO FCST KEEPING ONLY SCHC POPS FOR MON INTO TUE THEN INCREASE POPS TO 30-40 PCT CHC FOR WED AND THU WITH THE IDEA THAT ERN CANADA TROF WILL WEAKEN ALLOWING FOR MORE ENERGY FROM WRN CONUS TROF TO REACH UPPER GREAT LAKES. TEMPS SHOULD REMAIN BLO NORMAL THRU THE PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 127 AM EDT FRI APR 5 2013 VFR CONDITIONS EXPECTED THROUGH THE PERIOD AT ALL TAF SITES. PUT IN A CHANCE OF SOME SNOW LATE IN THE EVENING IN IWD WITH POSSIBILITY OF MVFR CIGS AND VIS AS NEXT WEATHER SYSTEM NEARS. THIS WILL CAUSE CLOUDS TO THICKEN AND LOWER AT CMX AND SAW IN THE EVENING. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 622 AM EDT FRI APR 5 2013 NW WINDS UP TO 25 KTS EARLY THIS MORNING OVER THE E HALF WILL DIMINISH STEADILY TODAY AS HI PRES IS FORECAST TO BUILD OVER UPR MI BY THIS AFTERNOON. LIGHT WINDS WILL SHIFT TO THE ESE AND INCREASE UP TO 20 KTS TONIGHT AS THE NEXT LO PRES SYSTEM IS FORECAST TO MOVE TO SW MN BY SAT MORNING. AS THE PRES GRADIENT TIGHTENS OVER LAKE SUP ON SAT/SAT NIGHT TO THE N OF THE LO TRACKING THRU THE CENTRAL LAKES... E-SE BACKING NE WINDS WILL INCREASE UP TO 25 TO 30 KTS BEFORE DIMINISHING AND FURTHER BACKING TO THE N ON SUN AS TRAILING HI PRES SHIFTS TOWARD THE UPPER LAKES. FOR EARLY NEXT WEEK...PLAN ON NE WINDS UP TO 20 KTS ON THE SE FLANK OF HI PRES OVER CENTRAL CANADA. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...VOSS AVIATION...07 MARINE...KC
AREA FORECAST DISCUSSION...UPDATED
NWS GAYLORD MI
122 AM EDT FRI APR 5 2013 .SYNOPSIS... ISSUED AT 344 PM EDT THU APR 4 2013 A COLD FRONT IS MOVING THROUGH NORTHERN MICHIGAN...BRINGING A PERIOD OF LIGHT RAIN AND SNOW FOR THIS AFTERNOON AND TONIGHT. SETTLED WEATHER WILL RETURN FOR A SHORT TIME ON FRIDAY...BEFORE ANOTHER STORM SYSTEM MOVES INTO NORTHERN MICHIGAN...BRINGING RAIN AND SNOW MIXED FOR SATURDAY INTO SUNDAY. && .UPDATE... ISSUED AT 1246 AM EDT FRI APR 5 2013 CHANGES THIS HOUR: ONLY CHANGE AT THIS TIME IS TO END FOG MENTION A LITTLE EARLIER OVERNIGHT AS VERY DRY UPSTREAM AIRMASS HAS BROUGHT A QUICK END TO WHAT WAS LOCALLY DENSE FOG LATE LAST EVENING. SHSN CHANCES TOWARDS DAYBREAK STILL LOOKING RATHER LOW GIVEN THE PAUCITY OF MOISTURE UPSTREAM...BUT LOW END POPS STILL ARE WARRANTED IN FAVORED NNW FLOW AREAS. UPDATE ISSUED AT 1115 PM EDT THU APR 4 2013 ALL SYNOPTICALLY DRIVEN SNOW HAS EXITED OUT OF OUR CWA LATE THIS EVENING ALONG THE DEPARTING COLD FRONT. RESIDUAL SCT/BKN LOW CLOUDS BEHIND THE FRONT ARE SHOWING SIGNS OF BECOMING LAKE ENHANCED PER LATEST 11U-3.9U SATELLITE LOOP. LAST FEW FRAMES FROM KMQT 88D SHOWS THE BEGINNINGS OF SOME VERY LIGHT LAKE EFFECT FLURRIES/SNOW SHOWERS THANKS TO CAA AND N/NW FLOW OFF OF LAKE SUPERIOR. AIRMASS FILTERING IN BEHIND THE COLD FRONT IS QUITE DRY...BUT WITH 850 MB TEMPS DROPPING INTO THE MID TEENS...EXPECT AT LEAST SOME N/NW FLOW LAKE FLURRIES/LIGHT SNOW SHOWERS WILL DEVELOP OVERNIGHT. LOW CLOUDS WILL DIMINISH OVERNIGHT AWAY FROM ANY LAKE INFLUENCES AS DRIER SYNOPTIC AIR ADVECTS INTO THE REGION. ALSO EXPECT AREAS OF FOG THAT DEVELOP ACROSS PORTIONS OF NRN LWR MICHIGAN WILL EVENTUALLY DISSIPATE LATE TONIGHT/EARLY FRIDAY THANKS TO THAT DRIER AIR. UPSTREAM DWPTS IN THE 20S CERTAINLY SUPPORTS OVERNIGHT LOWS IN THE 20S. UPDATE ISSUED AT 700 PM EDT THU APR 4 2013 LINE OF RAIN/SNOW SHOWERS ACCELERATED SE EARLY THIS EVENING IN RESPONSE TO A 125 KT 300 MB JET MAX DIGGING INTO THE WRN GREAT LAKES REGION. HAVE MADE SEVERAL MODIFICATIONS TO TIMING AS A RESULT...AND ALL PRECIP ASSOCIATED WITH THE FRONT SHOULD CLEAR OUR CWA WITHIN THE NEXT HOUR OR SO. SOME CLEARING WILL TAKE PLACE... EXPECT FOR LOCATIONS DOWNSTREAM OF LAKES SUPERIOR AND MICHIGAN UNDER THE DIRECTION OF N/NW FLOW. LAKE CLOUDS AND SOME FLURRIES/LIGHT SNOW SHOWERS SHOULD DEVELOP WITHIN THESE AREAS AND PERSIST THE REST OF THE NIGHT AND INTO FRIDAY. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 344 PM EDT THU APR 4 2013 THE CURRENT RADAR SHOWS A NARROW BAND OF PCPN SLOWLY DROPPING SOUTH ACROSS NORTHERN LOWER MICHIGAN. THIS NARROW AREA OF PRECIPITATION IS THE RESULT OF A COLD FRONT SINKING SOUTH OVER THE REGION. VIS SAT AND SFC OBS SHOW LIMITED MOISTURE EITHER SIDE OF THE BOUNDARY...WITH MOSTLY SUNNY SKIES OVER MUCH OF CENTRAL AND SOUTHERN MICHIGAN. SUN OVER THE SRN CWA FROM EARLIER TODAY...HAS ALLOWED AFTERNOON TEMPS IN THESE AREAS TO WARM QUICKLY INTO THE MID AND UPPER 40S...WHILE TEMPS REMAIN IN THE 30S OVER ERN UPPER NORTH OF THE BOUNDARY. OVERALL THE MAIN FORECAST CONCERNS TONIGHT THROUGH FRIDAY WILL BE TIMING AND TYPE OF PCPN TONIGHT WITH THE APPROACHING FRONT...ALONG WITH ANY LAKE INDUCED SNOWS FRIDAY ON THE BACKSIDE OF THE COLD FRONT. THE STORM SYSTEM CURRENTLY MOVING ACRS ONTARIO WILL QUICKLY EXIT INTO QUEBEC THIS EVENING. A COLD FRONT ASSOCIATED WITH THIS SYSTEM... WILL CONT TO DROP SOUTH ACRS NRN LWR MI THIS EVENING BEFORE EXITING EAST. EXPECT THE FRONT TO HAVE CLEARED NORTHERN LOWER MICHIGAN BTWN 03Z AND 06Z. THE ONLY PCPN ASSOCIATED WITH THIS BOUNDARY HAS BEEN LOCATED RIGHT ALONG THE FRONT...DUE TO THE EXTREMELY DRY AIR LOCATED OVER THE GREAT LAKES. HOWEVER SFC DEW PTS EVENTUALLY INCREASED FROM THE TEENS INTO THE MID 20S OVER THE STRAITS AS THE FRONT APPROACHED (ENOUGH TO GENERATE PCPN). HOWEVER PCPN TYPE AND CHC OVER THE REST OF THE CWA WILL BE DIFFICULT THIS EVENING AS THE FRONT DIPS SOUTH. TO THIS POINT...ALL OF THE PCPN HAS BEEN IN THE FORM OF SNOW OVER ERN UPPER AND THE STRAITS. THE LATEST RUC MODEL SOUNDINGS SHOW AN INVERTED V SIGNATURE IN THE LOWEST LAYERS FROM GAYLORD SOUTH TO THE SAGINAW BAY THIS EVENING...WITH OTHERWISE EXTREMELY DRY AIR ABOVE 850MB. ADDING COMPLICATIONS TO PCPN TYPE THIS EVENING IS THE VERTICAL TEMP PROFILES...AS MOST OF NRN LWR WARMED WELL INTO THE MID AND UPPER 40S DUE TO SOUTHWEST WINDS AND FULL SUN IN ADVANCE OF THE FRONT. HOWEVER PROGGED 850MB WET BULB TEMPS WOULD SUGGEST ENOUGH EVAP COOLING WITH ONSET OF ADVANCING MSTR TO AT LEAST MENTION A RAIN/SNOW MIX. OVERALL WILL CONTINUE THE LATEST TREND OF CHC POPS RAIN/SNOW MIXED OVER THE SRN HALF OF THE CWA AND SAGINAW BAY INTO THIS EVENING. COLDER AIR AND NORTHWEST FLOW RE-SETTLES INTO THE REGION OVERNIGHT AND FRIDAY ON THE BACK SIDE OF THE EXITING BOUNDARY. 850MB TEMPS QUICKLY DROP FROM ARND -4C THIS EVENING TO BETWEEN -12C AND -14C BY 12Z FRIDAY. SFC-850MB WINDS TURN FROM THE SOUTHWEST THIS EVENING IN ADVANCE OF THE BOUNDARY TO NNW FRIDAY. MODEL SOUNDINGS SUGGEST INVERSION HEIGHTS INCREASING TO NEAR 5K FT WHILE LINGERING LOW LVL MSTR EXTENDS TO AROUND THE -12C ISOTHERM. OVERALL MENTION CHC POPS IN NORTH FLOW SNOW BELTS EARLY FRIDAY. OTHERWISE WILL MENTION AT LEAST PARTLY SUNNY SKIES OVER THE REST OF THE CWA FRIDAY. WILL MENTION COOLER AFTN TEMPS FRIDAY...RANGING FROM AROUND FREEZING OVER ERN UPPER AND THE STRAITS TO THE LOWER 40S NEAR SAGINAW BAY. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 344 PM EDT THU APR 4 2013 LITTLE CHANGE FROM WHAT WAS SEEN YESTERDAY...WITH STILL PLENTY OF POTENTIAL FOR A VERY ACTIVE NEXT 7 DAYS OF WEATHER AS PERSISTENT -AO RELAXES AND DEEP SOUTHWEST MOISTURE RICH FLOW DEVELOPS ON FRONTSIDE OF DIGGING INTERMOUNTAIN WEST ENERGY. BIG WILD CARD REMAINS POTENTIAL INTERACTION WITH POLAR LOW SET TO ROTATE ACROSS EASTERN CANADA. EVENTUAL PLACEMENT OF THIS FEATURE WILL BE KEY IN DETERMINING LOCATION OF INTENSE LOW LEVEL THERMAL BOUNDARY AND SUBSEQUENT PATHWAY FOR ENERGY ROTATING OUT OF WESTERN TROUGH AXIS. WHILE ABOVE REMAINS A VERY LOW CONFIDENCE PORTION OF THE FORECAST...LEAD WAVE APPROACHING THE PACIFIC NORTHWEST (NICELY ILLUSTRATED ON LATEST WATER VAPOR IMAGERY) NOW WELL AGREED UPON TO IMPACT OUR WEATHER INTO THE START OF THIS WEEKEND. THIS WAVE WILL BRING ANOTHER BOUT OF WINTRY WEATHER TO THE NORTH WOODS SATURDAY...WITH INCREASING CONFIDENCE PARTS OF EASTERN UPPER WILL SEE A PERIOD OF ACCUMULATING SNOW. FORECAST CONCERNS INITIALLY DEAL WITH THIS LATTER SYSTEM...SPECIFICALLY SNOWFALL ACCUMULATIONS FOR EASTERN UPPER. MUCH MORE OF PROBABILISTIC APPROACH TAKING FOR THE REMAINDER OF THE FORECAST...WITH AT LEAST SOME ATTEMPT AT ADDRESSING MULTI- PERIOD PRECIP CHANCES AND TEMPERATURE TRENDS. GUIDANCE HAS LOCKED IN A SOLUTION SENDING PACIFIC NORTHWEST WAVE RAPIDLY EAST INTO THE NORTHERN PLAIN FRIDAY NIGHT...AND THROUGH NORTHERN MICHIGAN BY SATURDAY NIGHT. WEAKISH COUPLED JET STRUCTURE AND LOW LEVEL THERMAL BOUNDARY EXPECTED TO ENTICE RESPECTABLE SURFACE LOW PRESSURE DEVELOPMENT WITH THIS MID LEVEL WAVE...ITSELF EXPECTED TO SLICE THROUGH THE HEART OF NORTHERN LOWER MICHIGAN SATURDAY EVENING. ALTHOUGH WAVE ITSELF AND SURFACE FEATURE NOTHING TO WRITE HOME ABOUT...ACCOMPANYING DYNAMICS REMAIN IMPRESSIVE INDEED. MULTI-PERIOD TRENDS CONTINUE TO SUPPORT AGGRESSIVE WAA DRIVEN DYNAMICS...WITH NEAR 60 KNOT SOUTHWEST FLOW LOW LEVEL JET PERPENDICULAR TO THE 290K-295K PRESSURE SURFACES. DEEP LAYER FGEN SIGNAL ALSO PRESENT ALONG RETREATING COLD DOME...COLLOCATED NICELY WITH MAX WAA UPGLIDE ON NOSE OF LOW LEVEL JET. BEST JUXTAPOSITION OF THE ABOVE EXPECTED ACROSS FAR NORTHERN LOWER AND AREAS NORTH OF THE BRIDGE SATURDAY INTO SATURDAY EVENING. SYSTEM HAS A NICE SUBTROPICAL PACIFIC MOISTURE PLUME ALREADY ASSOCIATED WITH IT...SOME OF WHICH WILL BE ADVECTED INTO OUR AREA AS SYSTEM APPROACHES. COMBINE THIS WITH BRIEF WINDOW FOR SOME WESTERN GULF OF MEXICO MOISTURE CONTRIBUTION...AND PWAT VALUES SURGE TO AOA 0.75 INCHES LEVELS BY LATER SATURDAY. SAID ISENTROPIC SURFACES ALSO SHOW VERY RESPECTABLE MOISTURE...WITH MIXING RATIOS EXCEEDING 4 G/KG. LITTLE DOUBT SYSTEM HAS ALL THE EARMARKS TO BE A RATHER SUBSTANTIAL PRECIP PRODUCER... ALTHOUGH EXACTLY WHAT TYPE THAT PRECIP TAKES REMAINS A FORMIDABLE CHALLENGE. WILL USE ROCK-STEADY ECMWF DEPICTIONS FOR THERMAL FIELDS. THIS CONTINUES TO SUGGEST MAINLY SNOW AT THE ONSET EARLY SATURDAY...RAPIDLY CHANGING OVER TO LIQUID FROM SOUTHWEST TO NORTHEAST ACROSS NORTHERN LOWER MICHIGAN DURING THE MORNING. COULD SEE SOME MINOR SNOW ACCUMULATIONS...ON THE ORDER OF AN INCH OR SO...ESPECIALLY ACROSS THE HIGHER TERRAIN AREAS. WILL NEED TO WATCH FOR A PERIOD OF FREEZING RAIN AS WAA STRENGTHENS JUST OFF THE DECK. THIS SHOULD BE SHORT-LIVED EVENT (IF IT OCCURS AT ALL) AND NOT WORTHY OF A MENTION IN THE FORECAST. MUCH BIGGER PRECIP TYPE CHALLENGE ACROSS EASTERN UPPER...WITH STRONG DYNAMICS POSSIBLY OVERCOMING MARGINAL THERMAL PROFILES TO KEEP PRECIP MAINLY ALL SNOW...ESPECIALLY ALONG AND NORTH OF M-28. MODEL QPF FIELDS SOMEWHAT DISCONCERTING...WITH PROGS SUPPORTING A HALF INCH OR MORE OF LIQUID EQUIVALENT PRECIP BY LATER SATURDAY NIGHT. HEAVIER AMOUNTS NO DOUBT POSSIBLE GIVEN AMOUNT OF EARLIER MENTIONED DYNAMICS. SNOW RATIOS WILL NOT BE GREAT...ESPECIALLY SATURDAY AFTERNOON...WHEN SURFACE READINGS WILL LIKELY EXCEED FREEZING AND HIGH APRIL SUN ANGLE TAKES HOLD. STILL...COULD EASILY SEE SEVERAL INCHES OF HEAVY WET SNOW ACCUMULATION BY LATER SATURDAY NIGHT...WITH PERIODS OF HIGH INTENSITY SNOWFALL. NO HEADLINES FORTHCOMING ON THIS SHIFT...BUT IF ABOVE COMES TO FRUITION...COULD SEE ADVISORY LEVEL SNOW AMOUNTS FOR AT LEAST PARTS OF EASTERN UPPER. STAY TUNED! SYSTEM WINDS DOWN QUICKLY LATE SATURDAY NIGHT...LEAVING BEHIND A DRY SUNDAY AND SUNDAY EVENING. CONFIDENCE DROPS REMARKABLY HEADING THROUGH NEXT WORK WEEK...WITH GUIDANCE STRUGGLING WITH KEY INTERACTIONS TALKED ABOUT IN THE LEAD PARAGRAPH. PLENTY OF POTENTIAL FOR ADDITIONAL SIGNIFICANT SYSTEMS...WITH SOME DECENT SUPPORT FOR ONE SUCH SYSTEM TO IMPACT OUR AREA TO KICK OFF THE WEEK. EXACTLY HOW FAR NORTH THIS SYSTEM RIDES UP THROUGH THE OHIO VALLEY/SOUTHERN LAKES STILL FAR FROM BEING DETERMINED. DEPENDING ON SUCH...MAY SEE ENOUGH COLD AIR ALONG THE NORTHERN PERIPHERY OF ITS PRECIP SHIELD TO SUPPORT SOME WINTRY WEATHER. NO NEED TO GET TOO SPECIFIC...AND WILL BE FORCED TO RUN WITH A GUIDANCE CONSENSUS BLEND UNTIL A MORE DETERMINISTIC APPROACH CAN BE UTILIZED. SAME STORY HEADING THROUGH THE REMAINDER OF THE WEEK...WITH AGAIN THE POTENTIAL FOR ANOTHER WAVE TO ROTATE NORTHEAST OUT OF THE SOUTHERN PLAINS. TIMING AND PLACEMENT OF SUCH ALL OVER THE BOARD...AS IT WILL LIKELY REMAIN WITH BAROCLINIC AXIS SUBJECT TO MANY CHANGES PER CANADIAN TROUGHING AND PASSAGE OF EARLIER IN THE WEEK SYSTEMS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 121 AM EDT FRI APR 5 2013 SUMMARY: HIGH PRESSURE WILL BUILD INTO THE GREAT LAKES REGION TODAY WITH SOME MORNING LAKE ENHANCED CLOUDINESS GIVING WAY TO AMPLE SUNSHINE UNDER DIMINISHING NORTHWESTERLY WINDS. RESTRICTIONS: VFR CONDITIONS EXPECTED THROUGH THE UPCOMING TAF PERIOD. CAN/T RULE OUT A FEW FLURRIES FROM THE PRE-DAWN HOURS THROUGH MID MORNING AT TVC/MBL...BUT INCOMING AIRMASS IS TOO DRY TOO SUPPORT SIGNIFICANT SHSN DEVELOPMENT. CIGS MAY DROP TO 3-4KFT FOR A TIME AT TVC /AND POTENTIALLY AT MBL-PLN/...BUT EXPECT THESE TO REMAIN VFR BEFORE SCATTERING OUT BY LATE MORNING. WINDS: NORTHWEST WINDS 5-10KTS WILL CONTINUE THROUGH THE OVERNIGHT BEFORE INCREASING TO 10G16KTS FOR THE DAY ON FRIDAY WHILE VEERING NORTH NORTHWEST. WINDS WILL DIMINISH TO CALM OR LIGHT/VARIABLE THIS EVENING. && .MARINE... ISSUED AT 344 PM EDT THU APR 4 2013 GUSTY SOUTHWEST WINDS IN ADVANCE OF A FRONTAL BOUNDARY DROPPING SOUTH OVER NRN MI...WILL TURN NORTHWEST OVERNIGHT AND REMAIN BREEZY ON THE BACKSIDE OF THE EXITING BOUNDARY. RAIN/SNOW MIXED PCPN WILL AFFECT NRN MI NEARSHORE WATERS THIS EVENING AS BOUNDARY DROPS SOUTH...WITH SOME LAKE SNOWS POSSIBLE FRIDAY BEHIND THE FRONT. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...ARNOTT SYNOPSIS...KAB SHORT TERM...SWR LONG TERM...MSB AVIATION...ARNOTT MARINE...SWR
AREA FORECAST DISCUSSION...UPDATED
NWS GAYLORD MI
1248 AM EDT FRI APR 5 2013 .SYNOPSIS... ISSUED AT 344 PM EDT THU APR 4 2013 A COLD FRONT IS MOVING THROUGH NORTHERN MICHIGAN...BRINGING A PERIOD OF LIGHT RAIN AND SNOW FOR THIS AFTERNOON AND TONIGHT. SETTLED WEATHER WILL RETURN FOR A SHORT TIME ON FRIDAY...BEFORE ANOTHER STORM SYSTEM MOVES INTO NORTHERN MICHIGAN...BRINGING RAIN AND SNOW MIXED FOR SATURDAY INTO SUNDAY. && .UPDATE... ISSUED AT 1246 AM EDT FRI APR 5 2013 CHANGES THIS HOUR: ONLY CHANGE AT THIS TIME IS TO END FOG MENTION A LITTLE EARLIER OVERNIGHT AS VERY DRY UPSTREAM AIRMASS HAS BROUGHT A QUICK END TO WHAT WAS LOCALLY DENSE FOG LATE LAST EVENING. SHSN CHANCES TOWARDS DAYBREAK STILL LOOKING RATHER LOW GIVEN THE PAUCITY OF MOISTURE UPSTREAM...BUT LOW END POPS STILL ARE WARRANTED IN FAVORED NNW FLOW AREAS. UPDATE ISSUED AT 1115 PM EDT THU APR 4 2013 ALL SYNOPTICALLY DRIVEN SNOW HAS EXITED OUT OF OUR CWA LATE THIS EVENING ALONG THE DEPARTING COLD FRONT. RESIDUAL SCT/BKN LOW CLOUDS BEHIND THE FRONT ARE SHOWING SIGNS OF BECOMING LAKE ENHANCED PER LATEST 11U-3.9U SATELLITE LOOP. LAST FEW FRAMES FROM KMQT 88D SHOWS THE BEGINNINGS OF SOME VERY LIGHT LAKE EFFECT FLURRIES/SNOW SHOWERS THANKS TO CAA AND N/NW FLOW OFF OF LAKE SUPERIOR. AIRMASS FILTERING IN BEHIND THE COLD FRONT IS QUITE DRY...BUT WITH 850 MB TEMPS DROPPING INTO THE MID TEENS...EXPECT AT LEAST SOME N/NW FLOW LAKE FLURRIES/LIGHT SNOW SHOWERS WILL DEVELOP OVERNIGHT. LOW CLOUDS WILL DIMINISH OVERNIGHT AWAY FROM ANY LAKE INFLUENCES AS DRIER SYNOPTIC AIR ADVECTS INTO THE REGION. ALSO EXPECT AREAS OF FOG THAT DEVELOP ACROSS PORTIONS OF NRN LWR MICHIGAN WILL EVENTUALLY DISSIPATE LATE TONIGHT/EARLY FRIDAY THANKS TO THAT DRIER AIR. UPSTREAM DWPTS IN THE 20S CERTAINLY SUPPORTS OVERNIGHT LOWS IN THE 20S. UPDATE ISSUED AT 700 PM EDT THU APR 4 2013 LINE OF RAIN/SNOW SHOWERS ACCELERATED SE EARLY THIS EVENING IN RESPONSE TO A 125 KT 300 MB JET MAX DIGGING INTO THE WRN GREAT LAKES REGION. HAVE MADE SEVERAL MODIFICATIONS TO TIMING AS A RESULT...AND ALL PRECIP ASSOCIATED WITH THE FRONT SHOULD CLEAR OUR CWA WITHIN THE NEXT HOUR OR SO. SOME CLEARING WILL TAKE PLACE... EXPECT FOR LOCATIONS DOWNSTREAM OF LAKES SUPERIOR AND MICHIGAN UNDER THE DIRECTION OF N/NW FLOW. LAKE CLOUDS AND SOME FLURRIES/LIGHT SNOW SHOWERS SHOULD DEVELOP WITHIN THESE AREAS AND PERSIST THE REST OF THE NIGHT AND INTO FRIDAY. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 344 PM EDT THU APR 4 2013 THE CURRENT RADAR SHOWS A NARROW BAND OF PCPN SLOWLY DROPPING SOUTH ACROSS NORTHERN LOWER MICHIGAN. THIS NARROW AREA OF PRECIPITATION IS THE RESULT OF A COLD FRONT SINKING SOUTH OVER THE REGION. VIS SAT AND SFC OBS SHOW LIMITED MOISTURE EITHER SIDE OF THE BOUNDARY...WITH MOSTLY SUNNY SKIES OVER MUCH OF CENTRAL AND SOUTHERN MICHIGAN. SUN OVER THE SRN CWA FROM EARLIER TODAY...HAS ALLOWED AFTERNOON TEMPS IN THESE AREAS TO WARM QUICKLY INTO THE MID AND UPPER 40S...WHILE TEMPS REMAIN IN THE 30S OVER ERN UPPER NORTH OF THE BOUNDARY. OVERALL THE MAIN FORECAST CONCERNS TONIGHT THROUGH FRIDAY WILL BE TIMING AND TYPE OF PCPN TONIGHT WITH THE APPROACHING FRONT...ALONG WITH ANY LAKE INDUCED SNOWS FRIDAY ON THE BACKSIDE OF THE COLD FRONT. THE STORM SYSTEM CURRENTLY MOVING ACRS ONTARIO WILL QUICKLY EXIT INTO QUEBEC THIS EVENING. A COLD FRONT ASSOCIATED WITH THIS SYSTEM... WILL CONT TO DROP SOUTH ACRS NRN LWR MI THIS EVENING BEFORE EXITING EAST. EXPECT THE FRONT TO HAVE CLEARED NORTHERN LOWER MICHIGAN BTWN 03Z AND 06Z. THE ONLY PCPN ASSOCIATED WITH THIS BOUNDARY HAS BEEN LOCATED RIGHT ALONG THE FRONT...DUE TO THE EXTREMELY DRY AIR LOCATED OVER THE GREAT LAKES. HOWEVER SFC DEW PTS EVENTUALLY INCREASED FROM THE TEENS INTO THE MID 20S OVER THE STRAITS AS THE FRONT APPROACHED (ENOUGH TO GENERATE PCPN). HOWEVER PCPN TYPE AND CHC OVER THE REST OF THE CWA WILL BE DIFFICULT THIS EVENING AS THE FRONT DIPS SOUTH. TO THIS POINT...ALL OF THE PCPN HAS BEEN IN THE FORM OF SNOW OVER ERN UPPER AND THE STRAITS. THE LATEST RUC MODEL SOUNDINGS SHOW AN INVERTED V SIGNATURE IN THE LOWEST LAYERS FROM GAYLORD SOUTH TO THE SAGINAW BAY THIS EVENING...WITH OTHERWISE EXTREMELY DRY AIR ABOVE 850MB. ADDING COMPLICATIONS TO PCPN TYPE THIS EVENING IS THE VERTICAL TEMP PROFILES...AS MOST OF NRN LWR WARMED WELL INTO THE MID AND UPPER 40S DUE TO SOUTHWEST WINDS AND FULL SUN IN ADVANCE OF THE FRONT. HOWEVER PROGGED 850MB WET BULB TEMPS WOULD SUGGEST ENOUGH EVAP COOLING WITH ONSET OF ADVANCING MSTR TO AT LEAST MENTION A RAIN/SNOW MIX. OVERALL WILL CONTINUE THE LATEST TREND OF CHC POPS RAIN/SNOW MIXED OVER THE SRN HALF OF THE CWA AND SAGINAW BAY INTO THIS EVENING. COLDER AIR AND NORTHWEST FLOW RE-SETTLES INTO THE REGION OVERNIGHT AND FRIDAY ON THE BACK SIDE OF THE EXITING BOUNDARY. 850MB TEMPS QUICKLY DROP FROM ARND -4C THIS EVENING TO BETWEEN -12C AND -14C BY 12Z FRIDAY. SFC-850MB WINDS TURN FROM THE SOUTHWEST THIS EVENING IN ADVANCE OF THE BOUNDARY TO NNW FRIDAY. MODEL SOUNDINGS SUGGEST INVERSION HEIGHTS INCREASING TO NEAR 5K FT WHILE LINGERING LOW LVL MSTR EXTENDS TO AROUND THE -12C ISOTHERM. OVERALL MENTION CHC POPS IN NORTH FLOW SNOW BELTS EARLY FRIDAY. OTHERWISE WILL MENTION AT LEAST PARTLY SUNNY SKIES OVER THE REST OF THE CWA FRIDAY. WILL MENTION COOLER AFTN TEMPS FRIDAY...RANGING FROM AROUND FREEZING OVER ERN UPPER AND THE STRAITS TO THE LOWER 40S NEAR SAGINAW BAY. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 344 PM EDT THU APR 4 2013 LITTLE CHANGE FROM WHAT WAS SEEN YESTERDAY...WITH STILL PLENTY OF POTENTIAL FOR A VERY ACTIVE NEXT 7 DAYS OF WEATHER AS PERSISTENT -AO RELAXES AND DEEP SOUTHWEST MOISTURE RICH FLOW DEVELOPS ON FRONTSIDE OF DIGGING INTERMOUNTAIN WEST ENERGY. BIG WILD CARD REMAINS POTENTIAL INTERACTION WITH POLAR LOW SET TO ROTATE ACROSS EASTERN CANADA. EVENTUAL PLACEMENT OF THIS FEATURE WILL BE KEY IN DETERMINING LOCATION OF INTENSE LOW LEVEL THERMAL BOUNDARY AND SUBSEQUENT PATHWAY FOR ENERGY ROTATING OUT OF WESTERN TROUGH AXIS. WHILE ABOVE REMAINS A VERY LOW CONFIDENCE PORTION OF THE FORECAST...LEAD WAVE APPROACHING THE PACIFIC NORTHWEST (NICELY ILLUSTRATED ON LATEST WATER VAPOR IMAGERY) NOW WELL AGREED UPON TO IMPACT OUR WEATHER INTO THE START OF THIS WEEKEND. THIS WAVE WILL BRING ANOTHER BOUT OF WINTRY WEATHER TO THE NORTH WOODS SATURDAY...WITH INCREASING CONFIDENCE PARTS OF EASTERN UPPER WILL SEE A PERIOD OF ACCUMULATING SNOW. FORECAST CONCERNS INITIALLY DEAL WITH THIS LATTER SYSTEM...SPECIFICALLY SNOWFALL ACCUMULATIONS FOR EASTERN UPPER. MUCH MORE OF PROBABILISTIC APPROACH TAKING FOR THE REMAINDER OF THE FORECAST...WITH AT LEAST SOME ATTEMPT AT ADDRESSING MULTI- PERIOD PRECIP CHANCES AND TEMPERATURE TRENDS. GUIDANCE HAS LOCKED IN A SOLUTION SENDING PACIFIC NORTHWEST WAVE RAPIDLY EAST INTO THE NORTHERN PLAIN FRIDAY NIGHT...AND THROUGH NORTHERN MICHIGAN BY SATURDAY NIGHT. WEAKISH COUPLED JET STRUCTURE AND LOW LEVEL THERMAL BOUNDARY EXPECTED TO ENTICE RESPECTABLE SURFACE LOW PRESSURE DEVELOPMENT WITH THIS MID LEVEL WAVE...ITSELF EXPECTED TO SLICE THROUGH THE HEART OF NORTHERN LOWER MICHIGAN SATURDAY EVENING. ALTHOUGH WAVE ITSELF AND SURFACE FEATURE NOTHING TO WRITE HOME ABOUT...ACCOMPANYING DYNAMICS REMAIN IMPRESSIVE INDEED. MULTI-PERIOD TRENDS CONTINUE TO SUPPORT AGGRESSIVE WAA DRIVEN DYNAMICS...WITH NEAR 60 KNOT SOUTHWEST FLOW LOW LEVEL JET PERPENDICULAR TO THE 290K-295K PRESSURE SURFACES. DEEP LAYER FGEN SIGNAL ALSO PRESENT ALONG RETREATING COLD DOME...COLLOCATED NICELY WITH MAX WAA UPGLIDE ON NOSE OF LOW LEVEL JET. BEST JUXTAPOSITION OF THE ABOVE EXPECTED ACROSS FAR NORTHERN LOWER AND AREAS NORTH OF THE BRIDGE SATURDAY INTO SATURDAY EVENING. SYSTEM HAS A NICE SUBTROPICAL PACIFIC MOISTURE PLUME ALREADY ASSOCIATED WITH IT...SOME OF WHICH WILL BE ADVECTED INTO OUR AREA AS SYSTEM APPROACHES. COMBINE THIS WITH BRIEF WINDOW FOR SOME WESTERN GULF OF MEXICO MOISTURE CONTRIBUTION...AND PWAT VALUES SURGE TO AOA 0.75 INCHES LEVELS BY LATER SATURDAY. SAID ISENTROPIC SURFACES ALSO SHOW VERY RESPECTABLE MOISTURE...WITH MIXING RATIOS EXCEEDING 4 G/KG. LITTLE DOUBT SYSTEM HAS ALL THE EARMARKS TO BE A RATHER SUBSTANTIAL PRECIP PRODUCER... ALTHOUGH EXACTLY WHAT TYPE THAT PRECIP TAKES REMAINS A FORMIDABLE CHALLENGE. WILL USE ROCK-STEADY ECMWF DEPICTIONS FOR THERMAL FIELDS. THIS CONTINUES TO SUGGEST MAINLY SNOW AT THE ONSET EARLY SATURDAY...RAPIDLY CHANGING OVER TO LIQUID FROM SOUTHWEST TO NORTHEAST ACROSS NORTHERN LOWER MICHIGAN DURING THE MORNING. COULD SEE SOME MINOR SNOW ACCUMULATIONS...ON THE ORDER OF AN INCH OR SO...ESPECIALLY ACROSS THE HIGHER TERRAIN AREAS. WILL NEED TO WATCH FOR A PERIOD OF FREEZING RAIN AS WAA STRENGTHENS JUST OFF THE DECK. THIS SHOULD BE SHORT-LIVED EVENT (IF IT OCCURS AT ALL) AND NOT WORTHY OF A MENTION IN THE FORECAST. MUCH BIGGER PRECIP TYPE CHALLENGE ACROSS EASTERN UPPER...WITH STRONG DYNAMICS POSSIBLY OVERCOMING MARGINAL THERMAL PROFILES TO KEEP PRECIP MAINLY ALL SNOW...ESPECIALLY ALONG AND NORTH OF M-28. MODEL QPF FIELDS SOMEWHAT DISCONCERTING...WITH PROGS SUPPORTING A HALF INCH OR MORE OF LIQUID EQUIVALENT PRECIP BY LATER SATURDAY NIGHT. HEAVIER AMOUNTS NO DOUBT POSSIBLE GIVEN AMOUNT OF EARLIER MENTIONED DYNAMICS. SNOW RATIOS WILL NOT BE GREAT...ESPECIALLY SATURDAY AFTERNOON...WHEN SURFACE READINGS WILL LIKELY EXCEED FREEZING AND HIGH APRIL SUN ANGLE TAKES HOLD. STILL...COULD EASILY SEE SEVERAL INCHES OF HEAVY WET SNOW ACCUMULATION BY LATER SATURDAY NIGHT...WITH PERIODS OF HIGH INTENSITY SNOWFALL. NO HEADLINES FORTHCOMING ON THIS SHIFT...BUT IF ABOVE COMES TO FRUITION...COULD SEE ADVISORY LEVEL SNOW AMOUNTS FOR AT LEAST PARTS OF EASTERN UPPER. STAY TUNED! SYSTEM WINDS DOWN QUICKLY LATE SATURDAY NIGHT...LEAVING BEHIND A DRY SUNDAY AND SUNDAY EVENING. CONFIDENCE DROPS REMARKABLY HEADING THROUGH NEXT WORK WEEK...WITH GUIDANCE STRUGGLING WITH KEY INTERACTIONS TALKED ABOUT IN THE LEAD PARAGRAPH. PLENTY OF POTENTIAL FOR ADDITIONAL SIGNIFICANT SYSTEMS...WITH SOME DECENT SUPPORT FOR ONE SUCH SYSTEM TO IMPACT OUR AREA TO KICK OFF THE WEEK. EXACTLY HOW FAR NORTH THIS SYSTEM RIDES UP THROUGH THE OHIO VALLEY/SOUTHERN LAKES STILL FAR FROM BEING DETERMINED. DEPENDING ON SUCH...MAY SEE ENOUGH COLD AIR ALONG THE NORTHERN PERIPHERY OF ITS PRECIP SHIELD TO SUPPORT SOME WINTRY WEATHER. NO NEED TO GET TOO SPECIFIC...AND WILL BE FORCED TO RUN WITH A GUIDANCE CONSENSUS BLEND UNTIL A MORE DETERMINISTIC APPROACH CAN BE UTILIZED. SAME STORY HEADING THROUGH THE REMAINDER OF THE WEEK...WITH AGAIN THE POTENTIAL FOR ANOTHER WAVE TO ROTATE NORTHEAST OUT OF THE SOUTHERN PLAINS. TIMING AND PLACEMENT OF SUCH ALL OVER THE BOARD...AS IT WILL LIKELY REMAIN WITH BAROCLINIC AXIS SUBJECT TO MANY CHANGES PER CANADIAN TROUGHING AND PASSAGE OF EARLIER IN THE WEEK SYSTEMS. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING) ISSUED AT 700 PM EDT THU APR 4 2013 OVERALL CONDITIONS WILL REMAIN VFR THRU FRIDAY EVENING AS HIGH PRESSURE...SUBSIDENCE AND DRY AIR SLOWLY BUILD INTO NRN MICHIGAN. RESIDUAL LOW CLOUDS BEHIND THE COLD FRONT CURRENTLY TRACKING THRU NRN LWR MICHIGAN WILL DIMINISH THIS EVENING...EXCEPT FOR LOCATIONS DOWNWIND OF LAKES SUPERIOR AND MICHIGAN UNDER THE DIRECTION OF N/NW FLOW. A FEW FLURRIES OR LIGHT LAKE SNOW SHOWERS ARE POSSIBLE FOR TVC AND MBL TONIGHT...BUT CHANCES ARE LOW AND WILL LEAVE OUT OF THE TAF FOR NOW. N/NW WINDS BEHIND THE COLD FRONT WILL PERIODICALLY GUST TO 20 KTS. && .MARINE... ISSUED AT 344 PM EDT THU APR 4 2013 GUSTY SOUTHWEST WINDS IN ADVANCE OF A FRONTAL BOUNDARY DROPPING SOUTH OVER NRN MI...WILL TURN NORTHWEST OVERNIGHT AND REMAIN BREEZY ON THE BACKSIDE OF THE EXITING BOUNDARY. RAIN/SNOW MIXED PCPN WILL AFFECT NRN MI NEARSHORE WATERS THIS EVENING AS BOUNDARY DROPS SOUTH...WITH SOME LAKE SNOWS POSSIBLE FRIDAY BEHIND THE FRONT. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...ARNOTT SYNOPSIS...KAB SHORT TERM...SWR LONG TERM...MSB AVIATION...MR MARINE...SWR
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
912 PM CDT SAT APR 6 2013 .UPDATE... ISSUED AT 852 PM CDT SAT APR 6 2013 A WEAK COLD FRONT NOW EXTENDING FROM EASTERN IOWA SWWD THROUGH CENTRAL MO HAS BEEN THE FOCUS OF SOME SHOWERS THIS EVENING IN OUR CWA...WITH THUNDERSTORMS OVER EASTERN IOWA AND NW ILLINOIS. MODELS THIS EVENING...INCLUDING THE HRRR AND RUC...HAVE CONTINUED TO INDICATE A NARROW BAND OF SHOWERS TO PERSIST ALONG AND JUST AHEAD OF THE FRONT AS IT MOVES THROUGH OUR CWA TONIGHT. HAVE UPPED POPS ACROSS WEST CENTRAL IL THROUGH MIDNIGHT AND INCLUDED A MENTION OF THUNDER GIVEN MUCAPE VALUES BETWEEN 100-200 J/KG OVER EASTERN IOWA AND NW ILLINOIS WHICH HAVE BEEN ENOUGH TO RESULT IN A FAIRLY SOLID LINE OF THUNDERSTORMS THIS EVENING OVER THAT AREA. HOWEVER...GIVEN MUCH OF THE FORCING REMAINS ANCHORED NORTH OF THE CWA...A CONTINUED MENTION OF SOME SPOTTY SHOWERS REMAINS SUFFICIENT FOR THE REMAINDER OF THE AREA. ASIDE FROM THE AFOREMENTIONED CHANGES...THE REST OF THE FORECAST REMAINS ON TRACK THIS EVENING...WITH ONLY MINOR CHANGES NEEDED TO ACCOUNT FOR NEAR TERM TEMPERATURE TRENDS. JP && .SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT) ISSUED AT 322 PM CDT SAT APR 6 2013 THE WEAK COLD FRONT NOW EXTENDING THROUGH NW MO WILL MOVE SEWD INTO THE REGION TONIGHT AS THE ASSOCIATED SHORT WAVE TROF TRACKS ACROSS THE UPPER MS VALLEY INTO THE GREAT LAKES. MODEL CONSENSUS IS THE FRONT SHOULD BE IN THE VICINITY OF THE I-70 CORRIDOR AT 12Z SUNDAY. PRESENTLY THERE IS NOT MUCH MORE THAN MID CLOUDS AND SPINKLES OR A SPOT SHOWER AHEAD OF THE FRONT. SOME OF THE EXPLICIT GUIDANCE SUGGESTS A NARROW BROKEN LINE OF SHOWERS/THUNDERSTORMS WILL DEVELOP ALONG THE FRONT AS IT PUSHES INTO THE CWA. THIS LOOKS A BIT OVERDONE HOWEVER...AS THE FORCING IS WEAK AND OBSERVED MUCAPES ARE LESS THAN 100 J/KJ. CURRENT THINKING IS THERE MAY BE SOME SPOTTY SHOWERS WITH THE FRONT...PRIMARILY FROM EASTERN MO INTO WESTERN ILLINOIS. TEMPERTURES ON SUNDAY SHOULD BE AT LEAST COMPARABLE TO TODAY. THE EAST-WEST ORIENTED FRONT MAY OOZE A TAD FURTHER SOUTH ON SUNDAY MORNING BUT IS EXPECTED TO BECOME QUASI-STATIONARY IN THE VICINITY OF THE I-70 CORRIDOR IN THE AFTERNOON. THE PRECIPITATION THREAT SEEMS TO LARGELY BE DEPENDENT ON THE INSTABILITY WHICH LOOKS A BIT OVERDONE IN THESE INITIAL STAGES OF THE RETURN FLOW OWING TO TOO HIGH OF SURFACE DEW POINTS. THINKING AT THIS TIME IS THERE COULD BE SOME SCATTERED SHOWERS OR THUNDERSTORMS WITHIN THE BROAD FRONTAL ZONE...ESPECIALLY IN CENTRAL MO. THE PRECIPITATION CHANCES ARE EXPECTED TO RAMP UP CONSIDERABLY ON SUNDAY NIGHT ASSOCIATED WITH FORCING VIA A MIGRATORY SHORT WAVE WITHIN THE WSW FLOW ALOFT AND INTENSIFYING AND VEERING SWLY LLJ. THE MAIN FOCUS SHOULD BE ALONG AND NORTH OF I-70 WITHIN THE COOL SECTOR NORTH OF THE RETREATING BOUNDARY. GLASS .LONG TERM...(MONDAY THROUGH NEXT SATURDAY) ISSUED AT 322 PM CDT SAT APR 6 2013 FROM MONDAY INTO TUESDAY THE DETAILS IN THE FORECAST BECOME A BIT MORE DIFFICULT TO RESOLVE DUE TO MARKED DIFFERENCES IN THE POSITION AN EAST-WEST BOUNDARY THAT WILL RESIDE ACROSS EITHER NORTHERN MO OR FURTHER NORTH INTO IOWA. THE ECMWF HAS BEEN THE MOST INSISTENT WITH THE MORE SRN POSITION AND THUS MUCH WETTER...WHILE THE REMAINDER OF THE GUIDANCE SUITE KEEPS THE BOUNDARY ALONG OR NORTH OF THE IOWA/MISSOURI BORDER WITH LESSER PRECIPITATION CHANCES. ON MONDAY MORNING I THINK THAT ANY LINGERING THREAT OF SHOWERS AND THUNDERSTORMS WILL BE ALIGNED WITH THE SWLY LLJ AXIS AND BY AFTERNOON THE EML BUILDS IN STRONGLY AND RESULTS IN SUBSTANTIAL CAPPING OF THE WARM SECTOR. THE WARM SECTOR WILL CONTINUE TO MOISTEN AND DESTABILIZE INTO TUESDAY AND SHOULD REMAIN CAPPED TO SURFACE BASED STORMS SOUTH OF THE FRONT. AT THIS TIME I HAVE KEPT MY HIGHEST POPS IN THE MONDAY-TUESDAY TIME FRAME ACROSS NRN MO INTO WEST CENTRAL ILLINOIS WHERE THE FRONT MAY EXIST...WITH POPS TAPPERED SOUTHWARD. DEPENDING ON WHERE THE FRONT EVENTUALLY RESIDES I COULD BE UNDERDONE OR OVERDONE WITH THE PRECIPITATION THREAT. THE MAIN SHOW WITH THE DEEP PROGRESSIVE LONGWAVE TROF AND ASSOCIATED SURFACE FRONT ALSO REMAINS PROBLEMATIC WITH TIMING DIFFERENCES IN THE EASTWARD PROGRESSION AMONGST THE SLOWEST ECMWF...AND FASTER GFS...GEFS AND CANADIAN. ONE PLAUSIBLE SCENARIO IS THAT THE PLAINS SEVERE WEATHER EVENT ON TUESDAY WILL GROW UPSCALE INTO A LINE/QLCS AND SHIFT EASTWARD INTO THE AREA OVERNIGHT TUESDAY INTO WEDNESDAY MORNING. ANOTHER IS THAT THIS LINE MAY REACH INTO WESTERN MO IN A WEAKENING STATE LATE TUESDAY NIGHT AND THE MAIN EVENT MAYBE WED AFTERNOON AND EVENING IN THE CWA PER THE ECMWF. THUS SOMEWHERE IN THE LATE TUESDAY NIGHT- WEDNESDAY NIGHT TIME FRAME WE ARE LIKELY TO SEE SIGNIFICANT CONVECTION...SOME OF WHICH COULD BE SEVERE. A COOL DOWN IS FORECAST IN THE WAKE OF THE FRONT THURSDAY INTO FRIDAY WITH BROAD CYCLONIC FLOW ALOFT. GLASS && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 626 PM CDT SAT APR 6 2013 COLD FRONT HAS MOVED INTO NORTHWESTERN MO EARLY THIS EVENING AND SHOULD PROGRESS THROUGH THE FORECAST AREA BEFORE STALLING OUT ALONG THE I-70 CORRIDOR AFTER 08Z. FOR NOW WILL SEE GUSTY SOUTH WINDS DIMINISH BY 01Z. AS FOR CLOUDS...JUST MID AND HIGH CLOUDS EXPECTED THROUGH THE FORECAST PERIOD. ONCE FRONTAL BOUNDARY STALLS OUT...WINDS TO BECOME LIGHT AND VARIABLE AT TAF SITES WITH SOME PATCHY FOG POSSIBLE AT KCOU...KSUS AND KCPS BETWEEN 09Z AND 12Z. THEN FRONTAL BOUNDARY TO BEGIN TO SLIDE BACK TO THE NORTH...SO WINDS TO PICKUP FROM THE SOUTHEAST TO SOUTH ALONG I-70 CORRIDOR BY 16Z AND AROUND 21Z SUNDAY AT KUIN. SPECIFICS FOR KSTL...COLD FRONT HAS MOVED INTO NORTHWESTERN MO EARLY THIS EVENING AND SHOULD PROGRESS THROUGH THE FORECAST AREA BEFORE STALLING OUT ALONG THE I-70 CORRIDOR AFTER 08Z. FOR NOW WILL SEE GUSTY SOUTH WINDS DIMINISH BY 01Z. AS FOR CLOUDS...JUST MID AND HIGH CLOUDS EXPECTED THROUGH THE FORECAST PERIOD. ONCE FRONTAL BOUNDARY STALLS OUT...WINDS TO BECOME LIGHT AND VARIABLE AT KSTL BY 08Z SUNDAY. THEN FRONTAL BOUNDARY TO BEGIN TO SLIDE BACK TO THE NORTH...SO WINDS TO PICKUP FROM THE SOUTH BY 16Z SUNDAY. BEST CHANCE FOR RAIN THROUGH THE FORECAST PERIOD WILL BE AFTER 00Z MONDAY...FOR NOW TIMING HARD TO PIN DOWN...SO JUST ADDED PROB30 GROUP BETWEEN 02Z AND 06Z MONDAY. BYRD && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1230 PM CDT FRI APR 5 2013 .UPDATE... ISSUED AT 1116 AM CDT FRI APR 5 2013 AREAS OF CLOUD COVER HAVE THUS FAR LIMITED THE RISE IN TEMPERATURES THIS MORNING. WENT AHEAD AND UPDATED THE FORECAST TO LOWER MAX T/S A COUPLE DEGREES ACROSS THE BOARD. OTHERWISE NO CHANGES TO OUR CURRENT RED FLAG WARNING...EVEN WITH THE SLIGHTLY COOLER TEMPERATURES...STILL LOOKING AT WIDESPREAD SUB 20 PERCENT RH ACROSS FIRE ZONES 204 AND 210...WITH LOCALIZED AREAS OF 15 PERCENT. CRITICAL WIND SPEEDS ARE NOT THERE YET...BUT STILL ANTICIPATING GUSTS AOA 25 MPH DURING PEAK HEATING. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 356 AM CDT FRI APR 5 2013 A MODIFIED ARCTIC FRONT IS LINED UP FROM ROUGHLY KFNB TO KLBF TO E-KIEN. THE FRONT WILL LIFT NORTH TODAY AS LOW PRESSURE...CURRENTLY ACROSS NERN WY...MOVES EAST THROUGH SRN SD. THE TEMPERATURE FCST USES 50 PERCENT OF THE RAP13 AND A BLEND OF OTHER MODELS. THE RAP IS VERY WARM BUT GIVEN THE CLOUDS MOVING IN...IT IS PROBABLY TOO WARM. THE NAM RADAR AND THUNDERSTORM PRODUCTS SUGGEST ISOLATED HIGH BASED SHRA AND TSTM THIS AFTN AND THIS EVENING. LITTLE OR NO RAINFALL IS EXPECTED. AS THE SFC LOW TRACKS THROUGH SD TODAY AND INTO SRN MN TONIGHT...A PACIFIC COLD FRONT WILL DROP THROUGH THE FCST AREA. THIS WILL KEEP LOWS ON THE WARM SIDE WITH LOWS MAINLY IN THE 40S. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 356 AM CDT FRI APR 5 2013 SATURDAY WILL STILL BE ANOTHER MILD DAY AS MOSTLY SUNNY SKIES BEHIND THE PACIFIC COLD FRONT PREVAIL. HIGHS SHOULD PUSH IN THE 60S WHICH IS DOWN ABOUT 10 TO 15 DEGREES FROM FRIDAY...BUT STILL ABOVE NORMAL. SATURDAY NIGHT A TROUGH DEVELOPS ALONG THE FRONT RANGE AND WILL BRING A SLIGHT CHANCE FOR SHOWERS TO THE EASTERN PANHANDLE. MOISTURE IS LIMITED AND WILL HAVE TO OVERCOME A DRY LOWER LAYER THUS EXPECT AMOUNTS LIGHT. SUNDAY WILL SEE THE NEXT WAVE PUSH ONTO THE HIGH PLAINS. MOISTURE IS LIMITED WITH PRECIP WATER ONLY AROUND 75 PERCENT OF NORMAL...FOR APRIL. INSTABILITY INCREASES DURING THE AFTERNOON WITH HEATING...AND SHOULD BE ENOUGH TO SET OFF SOME THUNDERSTORMS. CAPE VALUES ONLY A FEW HUNDRED J/KG...HOWEVER GREATER VALUES NOT TO FAR TO THE SOUTH IN KS. NEXT WEEK WILL SEE A MAJOR LOW DIG TOWARDS THE 4 CORNERS THEN EJECT ONTO THE PLAINS BY MID WEEK. THE MODELS CONTINUE TO STRUGGLE ON TIMING AND STRENGTH OF THE SYSTEM...WHICH LEADS TO A LOWER THAN AVERAGE CONFIDENCE IN FORECAST. THE GFS CONTINUES TO BE A FASTER SOLUTION...WHILE THE ECMWF BRINGS UP THE REAR. INITIALLY THINK AS THE LOW PUSHES TOWARDS THE ROCKIES...SOME MOISTURE WILL ADVECT NORTH. WE MAY GET DRY SLOTTED SUNDAY NIGHT INTO MONDAY...AHEAD OF THE LOW. HOWEVER PRECIP WATER INCREASES TO AROUND AN INCH...WHICH IS CLOSER TO 2 SD...LATE MONDAY. NEG LI/S SHOULD LEAD TO SOME SHOWERS AND THUNDER ACROSS MOST OF THE AREA. THEN AS THE UPPER LOW EJECTS ONTO THE PLAINS...WILL SEE SOME COLD AIR DEVELOP ON THE BACK SIDE. THIS WILL ALSO WORK IN TANDEM WITH COOL TEMPS AT NIGHT. WILL NEED TO MENTION SOME SN IN THE NW AND A MIX TO THE SOUTH AND EAST. LATEST MEX GUIDANCE FOR TUES AND WED HOLD DAYTIME HIGHS IN THE NW IN THE 30S. WHICH IS POSSIBLE AS THE CLOUDS WILL LIMIT DIURNAL SWING. ANOTHER CONCERN IS THE TIGHT PRESSURE GRADIENT...WHICH WILL CREATE SOME WINDY CONDITIONS. THE SYSTEM IS VERY SLOW TO PUSH ACROSS THE PLAINS...WITH IMPACT THROUGH AT LEAST EARLY WEDNESDAY. FOR THE LATER PART OF THE WEEK A SECONDARY UPPER LEVEL DISTURBANCE ROTATES DOWN ACROSS THE WESTERN PLAINS. ALTHOUGH MODELS HAVE HIGH PRESSURE AT THE SURFACE...THE UPPER LEVEL WAVE SHOULD HAVE ENOUGH MOISTURE TO STILL PRODUCE CLOUDS AND SOME LIGHT RAIN OR SNOW. LONG WAY TROUGH FINALLY SHOULD BE EAST BY THURSDAY OR FRIDAY...WITH A RIDGE TO THE WEST. THIS WILL RESULT IN NW FLOW AND A TRAIN OF UPPER LEVEL SHORT WAVES. WILL LIKELY NEED TO MENTION AT LEAST SOME LIGHT PRECIP TOWARDS THE END OF THE WEEK...HOWEVER TIMING ISSUES ARE COMMON THIS FAR OUT AND WILL NOT BLANKET POPS. WILL MONITOR AND ADD WHEN CONFIDENCE IS HIGHER ON LOCATION AND TIMING. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1230 PM CDT FRI APR 5 2013 VFR EXPECTED FOR ALL TERMINALS TODAY AND TONIGHT. STILL SEE AN OPPORTUNITY FOR A STRAY TSTM OR TWO THIS AFTERNOON/EVENING ACROSS NORTHERN NEBRASKA...BUT OVERALL COVERAGE WILL BE ISOLATED AT BEST. DUE TO THE DRY LOWER LEVELS OF THE ATMOSPHERE...ERRATIC GUSTY WIND WOULD ACCOMPANY ANY STORM THAT WERE TO DEVELOP. OTHERWISE A STRONG PACIFIC COLD FRONT WILL CROSS THE REGION THIS EVENING/OVERNIGHT...A WIND SHIFT WILL ACCOMPANY THE PASSAGE WITH SFC WINDS VEERING FROM SOUTHERLY TO NORTHWESTERLY...AND STAYING GUSTY THROUGH MUCH OF THE FORECAST PERIOD. MODEL GUIDANCE INDICATES THE FRONT THROUGH KVTN AND KLBF FROM THE 04-06Z TIME FRAME. && .FIRE WEATHER... ISSUED AT 356 AM CDT FRI APR 5 2013 A WEAKNESS IN THE WIND FIELDS IS SHOWING UP ACROSS SWRN NEB. THUS...RELATIVE HUMIDITY WILL BE VERY LOW IN THAT AREA BUT WINDS MAY NOT BE STRONG ENOUGH FOR CRITICAL FIRE DANGER. STRONGER WEST WINDS SHOW UP ACROSS THE ERN NEB PANHANDLE. THESE WEST WINDS WILL SWEEP EAST THIS AFTN TO NEAR KVTN AND KTIF. SOUTH WINDS CONTINUE EAST OF HIGHWAY 83. PRESUMABLY...THIS WILL DRAW MORE MOIST AIR NORTH FROM KS AND OKLAHOMA. THE RAP MODEL IS VERY DRY AND SUGGESTS CRITICAL FIRE CONDITIONS COULD SPREAD THROUGHOUT WESTERN AND NORTH CENTRAL NEB THIS AFTERNOON. THIS IS AN OCCASIONAL BIAS THAT SHOWS IN THE MODEL BUT IT SENSES THE DRYNESS OF THE ARCTIC AIR AND INCORPORATES IT INTO THE AFTN WEATHER. THE MODEL COULD BE CORRECT TO A DEGREE. THE BEST FORECAST IS A BLEND OF THE RAP WHICH IS VERY DRY AND THE OTHER MODELS WHICH TEND TO BE TOO MOIST. && .LBF WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 8 PM CDT /7 PM MDT/ THIS EVENING FOR NEZ204-210. && $$ UPDATE...JACOBS SHORT TERM...CDC LONG TERM...MASEK AVIATION...JACOBS FIRE WEATHER...CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1116 AM CDT FRI APR 5 2013 .UPDATE... ISSUED AT 1116 AM CDT FRI APR 5 2013 AREAS OF CLOUD COVER HAVE THUS FAR LIMITED THE RISE IN TEMPERATURES THIS MORNING. WENT AHEAD AND UPDATED THE FORECAST TO LOWER MAX T/S A COUPLE DEGREES ACROSS THE BOARD. OTHERWISE NO CHANGES TO OUR CURRENT RED FLAG WARNING...EVEN WITH THE SLIGHTLY COOLER TEMPERATURES...STILL LOOKING AT WIDESPREAD SUB 20 PERCENT RH ACROSS FIRE ZONES 204 AND 210...WITH LOCALIZED AREAS OF 15 PERCENT. CRITICAL WIND SPEEDS ARE NOT THERE YET...BUT STILL ANTICIPATING GUSTS AOA 25 MPH DURING PEAK HEATING. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 356 AM CDT FRI APR 5 2013 A MODIFIED ARCTIC FRONT IS LINED UP FROM ROUGHLY KFNB TO KLBF TO E-KIEN. THE FRONT WILL LIFT NORTH TODAY AS LOW PRESSURE...CURRENTLY ACROSS NERN WY...MOVES EAST THROUGH SRN SD. THE TEMPERATURE FCST USES 50 PERCENT OF THE RAP13 AND A BLEND OF OTHER MODELS. THE RAP IS VERY WARM BUT GIVEN THE CLOUDS MOVING IN...IT IS PROBABLY TOO WARM. THE NAM RADAR AND THUNDERSTORM PRODUCTS SUGGEST ISOLATED HIGH BASED SHRA AND TSTM THIS AFTN AND THIS EVENING. LITTLE OR NO RAINFALL IS EXPECTED. AS THE SFC LOW TRACKS THROUGH SD TODAY AND INTO SRN MN TONIGHT...A PACIFIC COLD FRONT WILL DROP THROUGH THE FCST AREA. THIS WILL KEEP LOWS ON THE WARM SIDE WITH LOWS MAINLY IN THE 40S. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 356 AM CDT FRI APR 5 2013 SATURDAY WILL STILL BE ANOTHER MILD DAY AS MOSTLY SUNNY SKIES BEHIND THE PACIFIC COLD FRONT PREVAIL. HIGHS SHOULD PUSH IN THE 60S WHICH IS DOWN ABOUT 10 TO 15 DEGREES FROM FRIDAY...BUT STILL ABOVE NORMAL. SATURDAY NIGHT A TROUGH DEVELOPS ALONG THE FRONT RANGE AND WILL BRING A SLIGHT CHANCE FOR SHOWERS TO THE EASTERN PANHANDLE. MOISTURE IS LIMITED AND WILL HAVE TO OVERCOME A DRY LOWER LAYER THUS EXPECT AMOUNTS LIGHT. SUNDAY WILL SEE THE NEXT WAVE PUSH ONTO THE HIGH PLAINS. MOISTURE IS LIMITED WITH PRECIP WATER ONLY AROUND 75 PERCENT OF NORMAL...FOR APRIL. INSTABILITY INCREASES DURING THE AFTERNOON WITH HEATING...AND SHOULD BE ENOUGH TO SET OFF SOME THUNDERSTORMS. CAPE VALUES ONLY A FEW HUNDRED J/KG...HOWEVER GREATER VALUES NOT TO FAR TO THE SOUTH IN KS. NEXT WEEK WILL SEE A MAJOR LOW DIG TOWARDS THE 4 CORNERS THEN EJECT ONTO THE PLAINS BY MID WEEK. THE MODELS CONTINUE TO STRUGGLE ON TIMING AND STRENGTH OF THE SYSTEM...WHICH LEADS TO A LOWER THAN AVERAGE CONFIDENCE IN FORECAST. THE GFS CONTINUES TO BE A FASTER SOLUTION...WHILE THE ECMWF BRINGS UP THE REAR. INITIALLY THINK AS THE LOW PUSHES TOWARDS THE ROCKIES...SOME MOISTURE WILL ADVECT NORTH. WE MAY GET DRY SLOTTED SUNDAY NIGHT INTO MONDAY...AHEAD OF THE LOW. HOWEVER PRECIP WATER INCREASES TO AROUND AN INCH...WHICH IS CLOSER TO 2 SD...LATE MONDAY. NEG LI/S SHOULD LEAD TO SOME SHOWERS AND THUNDER ACROSS MOST OF THE AREA. THEN AS THE UPPER LOW EJECTS ONTO THE PLAINS...WILL SEE SOME COLD AIR DEVELOP ON THE BACK SIDE. THIS WILL ALSO WORK IN TANDEM WITH COOL TEMPS AT NIGHT. WILL NEED TO MENTION SOME SN IN THE NW AND A MIX TO THE SOUTH AND EAST. LATEST MEX GUIDANCE FOR TUES AND WED HOLD DAYTIME HIGHS IN THE NW IN THE 30S. WHICH IS POSSIBLE AS THE CLOUDS WILL LIMIT DIURNAL SWING. ANOTHER CONCERN IS THE TIGHT PRESSURE GRADIENT...WHICH WILL CREATE SOME WINDY CONDITIONS. THE SYSTEM IS VERY SLOW TO PUSH ACROSS THE PLAINS...WITH IMPACT THROUGH AT LEAST EARLY WEDNESDAY. FOR THE LATER PART OF THE WEEK A SECONDARY UPPER LEVEL DISTURBANCE ROTATES DOWN ACROSS THE WESTERN PLAINS. ALTHOUGH MODELS HAVE HIGH PRESSURE AT THE SURFACE...THE UPPER LEVEL WAVE SHOULD HAVE ENOUGH MOISTURE TO STILL PRODUCE CLOUDS AND SOME LIGHT RAIN OR SNOW. LONG WAY TROUGH FINALLY SHOULD BE EAST BY THURSDAY OR FRIDAY...WITH A RIDGE TO THE WEST. THIS WILL RESULT IN NW FLOW AND A TRAIN OF UPPER LEVEL SHORT WAVES. WILL LIKELY NEED TO MENTION AT LEAST SOME LIGHT PRECIP TOWARDS THE END OF THE WEEK...HOWEVER TIMING ISSUES ARE COMMON THIS FAR OUT AND WILL NOT BLANKET POPS. WILL MONITOR AND ADD WHEN CONFIDENCE IS HIGHER ON LOCATION AND TIMING. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 619 AM CDT FRI APR 5 2013 VFR IS EXPECTED ALL AREAS TODAY AND TONIGHT. ISOLATED AFTERNOON AND EVENING THUNDERSTORMS ARE POSSIBLE WITH THE APPROACH OF A STRONG PACIFIC COLD FRONT. THE FRONT IS EXPECTED TO PRODUCE A PERIOD OF GUSTY WINDS ACROSS NRN NEB TONIGHT. OTHERWISE SCT-BKN120-200 CIGS WILL CONTINUE THROUGH 06Z TONIGHT. && .FIRE WEATHER... ISSUED AT 356 AM CDT FRI APR 5 2013 A WEAKNESS IN THE WIND FIELDS IS SHOWING UP ACROSS SWRN NEB. THUS...RELATIVE HUMIDITY WILL BE VERY LOW IN THAT AREA BUT WINDS MAY NOT BE STRONG ENOUGH FOR CRITICAL FIRE DANGER. STRONGER WEST WINDS SHOW UP ACROSS THE ERN NEB PANHANDLE. THESE WEST WINDS WILL SWEEP EAST THIS AFTN TO NEAR KVTN AND KTIF. SOUTH WINDS CONTINUE EAST OF HIGHWAY 83. PRESUMABLY...THIS WILL DRAW MORE MOIST AIR NORTH FROM KS AND OKLAHOMA. THE RAP MODEL IS VERY DRY AND SUGGESTS CRITICAL FIRE CONDITIONS COULD SPREAD THROUGHOUT WESTERN AND NORTH CENTRAL NEB THIS AFTERNOON. THIS IS AN OCCASIONAL BIAS THAT SHOWS IN THE MODEL BUT IT SENSES THE DRYNESS OF THE ARCTIC AIR AND INCORPORATES IT INTO THE AFTN WEATHER. THE MODEL COULD BE CORRECT TO A DEGREE. THE BEST FORECAST IS A BLEND OF THE RAP WHICH IS VERY DRY AND THE OTHER MODELS WHICH TEND TO BE TOO MOIST. && .LBF WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 8 PM CDT /7 PM MDT/ THIS EVENING FOR NEZ204-210. && $$ UPDATE...JACOBS SHORT TERM...CDC LONG TERM...MASEK AVIATION...CDC FIRE WEATHER...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
623 AM CDT FRI APR 5 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 356 AM CDT FRI APR 5 2013 A MODIFIED ARCTIC FRONT IS LINED UP FROM ROUGHLY KFNB TO KLBF TO E-KIEN. THE FRONT WILL LIFT NORTH TODAY AS LOW PRESSURE...CURRENTLY ACROSS NERN WY...MOVES EAST THROUGH SRN SD. THE TEMPERATURE FCST USES 50 PERCENT OF THE RAP13 AND A BLEND OF OTHER MODELS. THE RAP IS VERY WARM BUT GIVEN THE CLOUDS MOVING IN...IT IS PROBABLY TOO WARM. THE NAM RADAR AND THUNDERSTORM PRODUCTS SUGGEST ISOLATED HIGH BASED SHRA AND TSTM THIS AFTN AND THIS EVENING. LITTLE OR NO RAINFALL IS EXPECTED. AS THE SFC LOW TRACKS THROUGH SD TODAY AND INTO SRN MN TONIGHT...A PACIFIC COLD FRONT WILL DROP THROUGH THE FCST AREA. THIS WILL KEEP LOWS ON THE WARM SIDE WITH LOWS MAINLY IN THE 40S. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 356 AM CDT FRI APR 5 2013 SATURDAY WILL STILL BE ANOTHER MILD DAY AS MOSTLY SUNNY SKIES BEHIND THE PACIFIC COLD FRONT PREVAIL. HIGHS SHOULD PUSH IN THE 60S WHICH IS DOWN ABOUT 10 TO 15 DEGREES FROM FRIDAY...BUT STILL ABOVE NORMAL. SATURDAY NIGHT A TROUGH DEVELOPS ALONG THE FRONT RANGE AND WILL BRING A SLIGHT CHANCE FOR SHOWERS TO THE EASTERN PANHANDLE. MOISTURE IS LIMITED AND WILL HAVE TO OVERCOME A DRY LOWER LAYER THUS EXPECT AMOUNTS LIGHT. SUNDAY WILL SEE THE NEXT WAVE PUSH ONTO THE HIGH PLAINS. MOISTURE IS LIMITED WITH PRECIP WATER ONLY AROUND 75 PERCENT OF NORMAL...FOR APRIL. INSTABILITY INCREASES DURING THE AFTERNOON WITH HEATING...AND SHOULD BE ENOUGH TO SET OFF SOME THUNDERSTORMS. CAPE VALUES ONLY A FEW HUNDRED J/KG...HOWEVER GREATER VALUES NOT TO FAR TO THE SOUTH IN KS. NEXT WEEK WILL SEE A MAJOR LOW DIG TOWARDS THE 4 CORNERS THEN EJECT ONTO THE PLAINS BY MID WEEK. THE MODELS CONTINUE TO STRUGGLE ON TIMING AND STRENGTH OF THE SYSTEM...WHICH LEADS TO A LOWER THAN AVERAGE CONFIDENCE IN FORECAST. THE GFS CONTINUES TO BE A FASTER SOLUTION...WHILE THE ECMWF BRINGS UP THE REAR. INITIALLY THINK AS THE LOW PUSHES TOWARDS THE ROCKIES...SOME MOISTURE WILL ADVECT NORTH. WE MAY GET DRY SLOTTED SUNDAY NIGHT INTO MONDAY...AHEAD OF THE LOW. HOWEVER PRECIP WATER INCREASES TO AROUND AN INCH...WHICH IS CLOSER TO 2 SD...LATE MONDAY. NEG LI/S SHOULD LEAD TO SOME SHOWERS AND THUNDER ACROSS MOST OF THE AREA. THEN AS THE UPPER LOW EJECTS ONTO THE PLAINS...WILL SEE SOME COLD AIR DEVELOP ON THE BACK SIDE. THIS WILL ALSO WORK IN TANDEM WITH COOL TEMPS AT NIGHT. WILL NEED TO MENTION SOME SN IN THE NW AND A MIX TO THE SOUTH AND EAST. LATEST MEX GUIDANCE FOR TUES AND WED HOLD DAYTIME HIGHS IN THE NW IN THE 30S. WHICH IS POSSIBLE AS THE CLOUDS WILL LIMIT DIURNAL SWING. ANOTHER CONCERN IS THE TIGHT PRESSURE GRADIENT...WHICH WILL CREATE SOME WINDY CONDITIONS. THE SYSTEM IS VERY SLOW TO PUSH ACROSS THE PLAINS...WITH IMPACT THROUGH AT LEAST EARLY WEDNESDAY. FOR THE LATER PART OF THE WEEK A SECONDARY UPPER LEVEL DISTURBANCE ROTATES DOWN ACROSS THE WESTERN PLAINS. ALTHOUGH MODELS HAVE HIGH PRESSURE AT THE SURFACE...THE UPPER LEVEL WAVE SHOULD HAVE ENOUGH MOISTURE TO STILL PRODUCE CLOUDS AND SOME LIGHT RAIN OR SNOW. LONG WAY TROUGH FINALLY SHOULD BE EAST BY THURSDAY OR FRIDAY...WITH A RIDGE TO THE WEST. THIS WILL RESULT IN NW FLOW AND A TRAIN OF UPPER LEVEL SHORT WAVES. WILL LIKELY NEED TO MENTION AT LEAST SOME LIGHT PRECIP TOWARDS THE END OF THE WEEK...HOWEVER TIMING ISSUES ARE COMMON THIS FAR OUT AND WILL NOT BLANKET POPS. WILL MONITOR AND ADD WHEN CONFIDENCE IS HIGHER ON LOCATION AND TIMING. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 619 AM CDT FRI APR 5 2013 VFR IS EXPECTED ALL AREAS TODAY AND TONIGHT. ISOLATED AFTERNOON AND EVENING THUNDERSTORMS ARE POSSIBLE WITH THE APPROACH OF A STRONG PACIFIC COLD FRONT. THE FRONT IS EXPECTED TO PRODUCE A PERIOD OF GUSTY WINDS ACROSS NRN NEB TONIGHT. OTHERWISE SCT-BKN120-200 CIGS WILL CONTINUE THROUGH 06Z TONIGHT. && .FIRE WEATHER... ISSUED AT 356 AM CDT FRI APR 5 2013 A WEAKNESS IN THE WIND FIELDS IS SHOWING UP ACROSS SWRN NEB. THUS...RELATIVE HUMIDITY WILL BE VERY LOW IN THAT AREA BUT WINDS MAY NOT BE STRONG ENOUGH FOR CRITICAL FIRE DANGER. STRONGER WEST WINDS SHOW UP ACROSS THE ERN NEB PANHANDLE. THESE WEST WINDS WILL SWEEP EAST THIS AFTN TO NEAR KVTN AND KTIF. SOUTH WINDS CONTINUE EAST OF HIGHWAY 83. PRESUMABLY...THIS WILL DRAW MORE MOIST AIR NORTH FROM KS AND OKLAHOMA. THE RAP MODEL IS VERY DRY AND SUGGESTS CRITICAL FIRE CONDITIONS COULD SPREAD THROUGHOUT WESTERN AND NORTH CENTRAL NEB THIS AFTERNOON. THIS IS AN OCCASIONAL BIAS THAT SHOWS IN THE MODEL BUT IT SENSES THE DRYNESS OF THE ARCTIC AIR AND INCORPORATES IT INTO THE AFTN WEATHER. THE MODEL COULD BE CORRECT TO A DEGREE. THE BEST FORECAST IS A BLEND OF THE RAP WHICH IS VERY DRY AND THE OTHER MODELS WHICH TEND TO BE TOO MOIST. && .LBF WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING FROM 1 PM CDT /NOON MDT/ THIS AFTERNOON TO 8 PM CDT /7 PM MDT/ THIS EVENING FOR NEZ204-210. && $$ SHORT TERM...CDC LONG TERM...MASEK AVIATION...CDC FIRE WEATHER...CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
357 AM CDT FRI APR 5 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 356 AM CDT FRI APR 5 2013 A MODIFIED ARCTIC FRONT IS LINED UP FROM ROUGHLY KFNB TO KLBF TO E-KIEN. THE FRONT WILL LIFT NORTH TODAY AS LOW PRESSURE...CURRENTLY ACROSS NERN WY...MOVES EAST THROUGH SRN SD. THE TEMPERATURE FCST USES 50 PERCENT OF THE RAP13 AND A BLEND OF OTHER MODELS. THE RAP IS VERY WARM BUT GIVEN THE CLOUDS MOVING IN...IT IS PROBABLY TOO WARM. THE NAM RADAR AND THUNDERSTORM PRODUCTS SUGGEST ISOLATED HIGH BASED SHRA AND TSTM THIS AFTN AND THIS EVENING. LITTLE OR NO RAINFALL IS EXPECTED. AS THE SFC LOW TRACKS THROUGH SD TODAY AND INTO SRN MN TONIGHT...A PACIFIC COLD FRONT WILL DROP THROUGH THE FCST AREA. THIS WILL KEEP LOWS ON THE WARM SIDE WITH LOWS MAINLY IN THE 40S. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 356 AM CDT FRI APR 5 2013 SATURDAY WILL STILL BE ANOTHER MILD DAY AS MOSTLY SUNNY SKIES BEHIND THE PACIFIC COLD FRONT PREVAIL. HIGHS SHOULD PUSH IN THE 60S WHICH IS DOWN ABOUT 10 TO 15 DEGREES FROM FRIDAY...BUT STILL ABOVE NORMAL. SATURDAY NIGHT A TROUGH DEVELOPS ALONG THE FRONT RANGE AND WILL BRING A SLIGHT CHANCE FOR SHOWERS TO THE EASTERN PANHANDLE. MOISTURE IS LIMITED AND WILL HAVE TO OVERCOME A DRY LOWER LAYER THUS EXPECT AMOUNTS LIGHT. SUNDAY WILL SEE THE NEXT WAVE PUSH ONTO THE HIGH PLAINS. MOISTURE IS LIMITED WITH PRECIP WATER ONLY AROUND 75 PERCENT OF NORMAL...FOR APRIL. INSTABILITY INCREASES DURING THE AFTERNOON WITH HEATING...AND SHOULD BE ENOUGH TO SET OFF SOME THUNDERSTORMS. CAPE VALUES ONLY A FEW HUNDRED J/KG...HOWEVER GREATER VALUES NOT TO FAR TO THE SOUTH IN KS. NEXT WEEK WILL SEE A MAJOR LOW DIG TOWARDS THE 4 CORNERS THEN EJECT ONTO THE PLAINS BY MID WEEK. THE MODELS CONTINUE TO STRUGGLE ON TIMING AND STRENGTH OF THE SYSTEM...WHICH LEADS TO A LOWER THAN AVERAGE CONFIDENCE IN FORECAST. THE GFS CONTINUES TO BE A FASTER SOLUTION...WHILE THE ECMWF BRINGS UP THE REAR. INITIALLY THINK AS THE LOW PUSHES TOWARDS THE ROCKIES...SOME MOISTURE WILL ADVECT NORTH. WE MAY GET DRY SLOTTED SUNDAY NIGHT INTO MONDAY...AHEAD OF THE LOW. HOWEVER PRECIP WATER INCREASES TO AROUND AN INCH...WHICH IS CLOSER TO 2 SD...LATE MONDAY. NEG LI/S SHOULD LEAD TO SOME SHOWERS AND THUNDER ACROSS MOST OF THE AREA. THEN AS THE UPPER LOW EJECTS ONTO THE PLAINS...WILL SEE SOME COLD AIR DEVELOP ON THE BACK SIDE. THIS WILL ALSO WORK IN TANDEM WITH COOL TEMPS AT NIGHT. WILL NEED TO MENTION SOME SN IN THE NW AND A MIX TO THE SOUTH AND EAST. LATEST MEX GUIDANCE FOR TUES AND WED HOLD DAYTIME HIGHS IN THE NW IN THE 30S. WHICH IS POSSIBLE AS THE CLOUDS WILL LIMIT DIURNAL SWING. ANOTHER CONCERN IS THE TIGHT PRESSURE GRADIENT...WHICH WILL CREATE SOME WINDY CONDITIONS. THE SYSTEM IS VERY SLOW TO PUSH ACROSS THE PLAINS...WITH IMPACT THROUGH AT LEAST EARLY WEDNESDAY. FOR THE LATER PART OF THE WEEK A SECONDARY UPPER LEVEL DISTURBANCE ROTATES DOWN ACROSS THE WESTERN PLAINS. ALTHOUGH MODELS HAVE HIGH PRESSURE AT THE SURFACE...THE UPPER LEVEL WAVE SHOULD HAVE ENOUGH MOISTURE TO STILL PRODUCE CLOUDS AND SOME LIGHT RAIN OR SNOW. LONG WAY TROUGH FINALLY SHOULD BE EAST BY THURSDAY OR FRIDAY...WITH A RIDGE TO THE WEST. THIS WILL RESULT IN NW FLOW AND A TRAIN OF UPPER LEVEL SHORT WAVES. WILL LIKELY NEED TO MENTION AT LEAST SOME LIGHT PRECIP TOWARDS THE END OF THE WEEK...HOWEVER TIMING ISSUES ARE COMMON THIS FAR OUT AND WILL NOT BLANKET POPS. WILL MONITOR AND ADD WHEN CONFIDENCE IS HIGHER ON LOCATION AND TIMING. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1234 AM CDT FRI APR 5 2013 HIGH LEVEL CLOUDINESS AON 20000 FT AGL WILL BEGIN TO MOVE INTO WESTERN AND NORTH CENTRAL NEBRASKA OVERNIGHT WITH BROKEN CIGS EXPECTED FRIDAY MORNING. BROKEN CLOUD COVERAGE WILL PERSIST THROUGH FRIDAY EVENING. CIGS MAY LOWER TO 12000 TO 15000 FT AGL FRIDAY EVENING AS A FRONTAL BOUNDARY APPROACHES WESTERN AND NORTH CENTRAL NEBRASKA. SOUTHERLY WINDS FRIDAY WILL BEGIN TO SHIFT TO THE SOUTHWEST...THEN WEST FRIDAY EVENING. WIND SPEEDS FRIDAY AND FRIDAY EVENING WILL RANGE FROM 10 TO 20 KTS WITH SOME GUSTS UP TO 25 KTS POSSIBLE FRIDAY EVENING. && .FIRE WEATHER... ISSUED AT 356 AM CDT FRI APR 5 2013 A WEAKNESS IN THE WIND FIELDS IS SHOWING UP ACROSS SWRN NEB. THUS...RELATIVE HUMIDITY WILL BE VERY LOW IN THAT AREA BUT WINDS MAY NOT BE STRONG ENOUGH FOR CRITICAL FIRE DANGER. STRONGER WEST WINDS SHOW UP ACROSS THE ERN NEB PANHANDLE. THESE WEST WINDS WILL SWEEP EAST THIS AFTN TO NEAR KVTN AND KTIF. SOUTH WINDS CONTINUE EAST OF HIGHWAY 83. PRESUMABLY...THIS WILL DRAW MORE MOIST AIR NORTH FROM KS AND OKLAHOMA. THE RAP MODEL IS VERY DRY AND SUGGESTS CRITICAL FIRE CONDITIONS COULD SPREAD THROUGHOUT WESTERN AND NORTH CENTRAL NEB THIS AFTERNOON. THIS IS AN OCCASIONAL BIAS THAT SHOWS IN THE MODEL BUT IT SENSES THE DRYNESS OF THE ARCTIC AIR AND INCORPORATES IT INTO THE AFTN WEATHER. THE MODEL COULD BE CORRECT TO A DEGREE. THE BEST FORECAST IS A BLEND OF THE RAP WHICH IS VERY DRY AND THE OTHER MODELS WHICH TEND TO BE TOO MOIST. && .LBF WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING FROM 1 PM CDT /NOON MDT/ THIS AFTERNOON TO 8 PM CDT /7 PM MDT/ THIS EVENING FOR NEZ204-210. && $$ SHORT TERM...CDC LONG TERM...MASEK AVIATION...CDC FIRE WEATHER...CDC
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
126 PM EDT FRI APR 5 2013 .SYNOPSIS... LOW PRESSURE SYSTEM JUST OFF THE NORTH CAROLINA COAST WILL CONTINUE TO LIFT OFF TO THE NORTHEAST AWAY FROM THE AREA THROUGH TODAY. HIGH PRESSURE WILL BUILD IN BEHIND THIS STORM SYSTEM... BRINGING A WARMING TREND AND SPRING-LIKE TEMPERATURES THROUGH NEXT WEEK. A MORE SUMMER-LIKE PATTERN SETS UP THROUGH MID WEEK AS BERMUDA HIGH PRESSURE DOMINATES BEFORE A COLD FRONT APPROACHES FROM THE WEST TOWARD LATE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 12:30 PM FRIDAY...OTHER THAN FOR GEORGETOWN COUNTY THE LATEST GUIDANCE AND RADAR LOOPS SUGGEST THAT PRECIP HAS ENDED FOR THE DAY. HAVE ALREADY CUT BACK ON POPS WITH THE LATEST ISSUANCES...AND WILL LIKELY MAY DROP POPS COMPLETELY WITH THE NEXT FORECAST PACKAGE. PREVIOUS DISCUSSION FOLLOWS: AN UPPER LEVEL DISTURBANCE MOVING RAPIDLY NORTH THROUGH GEORGIA AND NOW SOUTH CAROLINA HAS PRODUCED AN IMPRESSIVE AREA OF SHOWERS AND THUNDERSTORMS EXTENDING FROM GEORGETOWN SC SOUTH BACK INTO WAYCROSS AND AMERICUS GA VICINITY. THIS CONVECTION IS ELEVATED WITH THE LIFTING PARCEL LEVEL PROBABLY IN THE VICINITY OF 10000 FT AGL OR 700 MB. LATEST RUC ANALYSIS SHOWS LAPSE RATES IN THE 700-500 MB LAYER ARE EXCEEDING 7C/KM...AND FORECAST SOUNDINGS FROM VIRTUALLY ANY MODEL SHOW STEEP LAPSE RATES CONTINUING FOR AT LEAST ANOTHER 100 MB HIGHER IN THE ATMOSPHERE. I HAVE INCREASED POPS MAINLY ALONG THE SC COAST AND OFFSHORE FOR THE MORNING HOURS TO ACCOUNT FOR THIS ACTIVITY. FORTUNATELY THERE IS NO SEVERE WEATHER THREAT OWNING TO THE DEEP FRONTAL INVERSION BELOW THE STORMS AND SMALL CAPE VALUES ALOFT LIMITING POTENTIAL HAIL PRODUCTION. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... SURFACE LOW PRESSURE MOVED ALMOST DIRECTLY OVER ILM AROUND MIDNIGHT. NOW THAT THE LOW IS RACING NORTHEAST ACROSS EXTREME EASTERN NC COOL AIR HAS RUSHED DOWN TO THE CAPE FEAR AND GRAND STRAND BEACHES. LOW STRATUS CLOUDS WILL BE VERY TOUGH TO ERODE TODAY...AND IN FACT MODELS SUGGEST A SOLID GRAY OVERCAST WILL PERSIST THROUGH THE MORNING HOURS...RELUCTANTLY LIFTING INTO A SCT-BKN STRATOCUMULUS DECK SOMETIME IN THE 11 AM TO 2 PM PERIOD. IT APPEARS THE NAM HAS A BETTER HANDLE ON THE LATER CLOUD BURNOFF THAN THE GFS...THEREFORE MY FORECAST HIGHS ARE CLOSE THE NAM AND RANGE FROM THE UPPER 50S NEAR THE COAST TO AROUND 60 INLAND...10-13 DEGREES BELOW NORMAL. OF MORE IMMEDIATE CONCERN IS A CLUSTER OF THUNDERSTORMS ACROSS SOUTHERN GEORGIA ASSOCIATED WITH AN 500 MB VORT MAX ROTATING NORTHEASTWARD AROUND THE MAIN UPPER LOW STILL BACK ON THE MISSISSIPPI-ALABAMA BORDER. THIS CONVECTION APPEARS TO BE BASED AROUND 700 MB AND IS TAKING ADVANTAGE OF STEEPENING LAPSE RATES IN THE 700-400 MB LAYER AS COLD AIR WITH THE UPPER LOW ADVECTS ACROSS THE SOUTHEAST. IT IS POSSIBLE THESE SHOWERS AND THUNDERSTORMS WILL AFFECT COASTAL SOUTH CAROLINA LATER THIS MORNING...WHERE I HAVE A 30-40 PERCENT POP IN THE FORECAST. POPS ELSEWHERE ARE IN THE 10-20 PERCENT RANGE HEDGING FOR ANY EXPANSION IN THIS AREA OF ELEVATED CONVECTION. THE AFOREMENTIONED UPPER LOW WILL MOVE EAST ACROSS ALABAMA AND GEORGIA THIS MORNING...THEN INTO SOUTH CAROLINA BY MID AFTERNOON. LOW AND MID CLOUDS MAY CONTINUE ALONG THE COAST INTO THE EVENING HOURS BUT CLEARING SKIES SHOULD DEVELOP FROM WEST TO EAST AS THE UPPER LOW MOVES ACROSS. A NEW AREA OF SURFACE LOW PRESSURE WILL DEVELOP WELL OFF THE GA/SC COAST LATE THIS AFTERNOON IN ADVANCE OF THE UPPER SYSTEM. THIS NEW LOW SHOULD REMAIN TOO FAR AWAY FOR ANY DIRECT IMPACTS ON OUR AREA...BUT NORTHERLY FLOW BEHIND THIS LOW WILL HELP MAINLY A CHILLY AIRMASS ACROSS THE CAROLINAS TONIGHT WITH LOWS FALLING TO 40-45...A FEW DEGREES BELOW NORMAL. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN OVER THE SOUTHEAST THROUGH THE WEEKEND. A COOLER NORTHERLY FLOW INITIALLY WILL WEAKEN AND BECOME LIGHT AS IT VEERS AROUND THROUGH SAT NIGHT AS CENTER OF HIGH SHIFTS CLOSER OVERHEAD AND THEN OFF SHORE BY MORNING. THE MAX CAA WILL CUT OFF EARLY SATURDAY AS 850 TEMPS DROP CLOSE TO 3C. EXPECT AFTERNOON HIGHS TO ONCE AGAIN REMAIN BELOW NORMAL REACHING INTO THE LOW TO MID 60S. CALM WINDS AND CLEAR SKIES SATURDAY NIGHT WILL PROVIDE MORE IDEAL RADIATIONAL COOLING CONDITIONS WITH TEMPS DROPPING INTO THE LOWER END OF THE 40S MOST PLACES...BUT SLIGHTLY WARMER AT THE BEACHES. BY SUNDAY A RETURN FLOW WILL SET UP WITH LIGHT SOUTHERLY WINDS BEGINNING A WARMING TREND INTO NEXT WEEK. TEMPS WILL APPROACH NORMAL VALUES FOR THIS TIME OF YEAR WITH HIGH TEMPS JUST REACHING INTO THE 70S UNDER PLENTY OF SUNSHINE. OVERALL A BEAUTIFUL WEEKEND WITH LOTS OF SPRING SUNSHINE BUT SLIGHTLY COOLER TEMPS. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 3 AM FRIDAY...HEADING INTO A MORE SUMMER LIKE PATTERN FOR THIS TIME OF YEAR. BERMUDA HIGH PRESSURE WITH A WARMER MOISTER SOUTHERLY RETURN FLOW THROUGH THE PERIOD. A DEEP RIDGE BUILDS ALOFT WITH HEIGHT RISES PEAKING MID WEEK UP CLOSE TO 585 DM. AS THE MID TO UPPER RIDGE BUILDS UP THE EAST COAST A DEEPENING TROUGH WILL DIG DOWN THROUGH THE MID WEST. ALTHOUGH THE RIDGE HOLDS ON TIGHT THROUGH MUCH OF THE WORK WEEK...THE TROUGH FINALLY MOVES EAST TOWARD THE AREA PUSHING A COLD FRONT OUR WAY BY THURS NIGHT INTO FRIDAY. MODELS HAVE PUSHED THE TIMING BACK A BIT AND THEREFORE LOOKS LIKE NICE WEATHER WILL HOLD OUT THROUGH THURSDAY. OVERALL A RAIN FREE WEEK WITH A SHARP WARMING TREND BRINGING TEMPS TO SEVERAL DEGREES ABOVE NORMAL WITH HIGH TEMPS FLIRTING WITH 80 OR SLIGHTLY ABOVE IN PLACES AND MIN TEMPS CLOSE TO WHAT WE HAVE BEEN EXPERIENCING FOR HIGH TEMPS LATELY. THE COOLER OCEAN TEMPS WILL MAXIMIZE THE DIFFERENTIAL HEATING ALLOWING FOR A STRONG SEA BREEZE TO CARRY FAR INLAND MOST AFTERNOONS. THIS WILL BRING COOLER AIR INLAND BUT WILL ALSO KEEP THE BEACHES MUCH COOLER. THE SEA BREEZE WILL ALSO PROVIDE A FOCAL POINT FOR ENOUGH CONVERGENCE TO PRODUCE CU EACH AFTERNOON AND MAY SEE SOME PASSING HIGH CLOUDS BUT OTHERWISE SHOULD SEE A GOOD DEAL OF SUNSHINE THROUGH THE WEEK WITH ANY PCP HOLDING OFF UNTIL LATE THURS INTO FRIDAY. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AS OF 18Z...VISIBLE SATELLITE IMAGERY SHOWS THE LOW CLOUD DECK IS THINNING NEAR KFLO/KLBT AS THE STRATUS IS BEGINNING TO ERODE. ALONG THE COAST...LOW MVFR CIGS ARE STILL IN PLACE AND WILL LIKELY PERSIST FOR THE NEXT COUPLE HOURS. ANY LINGERING MVFR CIGS SHOULD LIFT TO VFR BY LATE AFTERNOON. NORTH WINDS AOB 10 KTS TODAY WILL DIMINISH TO AROUND 5 KTS TONIGHT. THE SKIES WILL BEGIN CLEARING AFTER 00Z SATURDAY AS AN UPPER TROUGH CLEARS THE CAROLINA COAST. SFC HIGH PRESSURE WILL BUILD IN FROM THE NORTH TOMORROW MORNING...BRINGING SUNNY SKIES AND NORTHEAST WINDS 8-12 KTS ACROSS OUR CWA. EXTENDED OUTLOOK...VFR CONDITIONS WILL PREVAIL THROUGH WEDNESDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 12:30 PM FRIDAY...LATEST OBS AND GUIDANCE SUGGEST THAT WE CAN DROP SMALL CRAFT ADVISORIES EARLY FOR ALL THE REMAINING COASTAL WATERS. IT IS LIKELY WE ARE NOW ONLY SEEING 6 FOOTERS OVER THE OUTER EDGES OF THE COASTAL WATERS. PREVIOUS DISCUSSION FOLLOWS: TWO CHANGES HAVE BEEN MADE TO THE MARINE FORECAST THIS MORNING. THE FIRST IS TO INCREASE SHOWER AND T-STORM CHANCES THROUGH THE MORNING HOURS AS THE WILMINGTON AND CHARLESTON RADARS ARE SHOWING AN IMPRESSIVE AREA OF SHOWERS AND STORMS MOVING RAPIDLY NORTHEAST ALONG THE COAST. THE SOUTH CAROLINA COASTAL WATERS WILL BE MOST STRONGLY AFFECTED BY THIS ACTIVITY...WHICH SHOULD TAPER OFF BY NOON. ALSO...OBSERVED WIND SPEEDS ARE ABOUT 5 KNOTS STRONGER THAN EXPECTED ACROSS THE WATERS NORTH OF CAPE FEAR...WHERE RECENTLY GUSTS AT BOTH WRIGHTSVILLE BEACH AND THE FRYING PAN SHOALS BUOY OFFSHORE HAVE BEEN AROUND 20 KNOTS. NO OTHER SIGNIFICANT CHANGES HAVE BEEN MADE. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... SURFACE LOW PRESSURE MOVED OVER WILMINGTON AROUND MIDNIGHT AND IS NOW RACING NORTHEAST ACROSS THE PAMLICO SOUND. NORTHWESTERLY WINDS BEHIND THIS LOW HAVE PUSHED THE COLD FRONT A CONSIDERABLE DISTANCE FROM SHORE...AND COOL NORTHWEST TO NORTH WINDS SHOULD CONTINUE THROUGH THE DAY. STRONG WINDS YESTERDAY STILL HAVE THE SEA STATE QUITE AGITATED AND IT WILL TAKE MOST OF THE DAY FOR SEAS TO DECAY BELOW 6 FEET. FOR THIS REASON THE SMALL CRAFT ADVISORY WILL REMAIN POSTED INTO THE AFTERNOON HOURS FOR THE SC COASTAL WATERS...AND UNTIL THIS EVENING FOR THE NC WATERS. AN APPROACHING UPPER LEVEL LOW WILL INDUCE A NEW LOW TO DEVELOP WELL OFF THE SC COAST LATE THIS AFTERNOON. WHILE THIS NEW LOW WILL HAVE NO DIRECT IMPACTS LOCALLY...IT WILL HELP TO ENHANCE THE NORTHERLY WINDS SOMEWHAT WITH WIND SPEEDS PERHAPS ECLIPSING 15 KNOTS OVERNIGHT...ESPECIALLY AWAY FROM SHORE. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN INTO THE LOCAL WATERS THROUGH SATURDAY BEFORE SHIFTING CLOSER OVERHEAD SAT NIGHT AND THEN OFF SHORE THROUGH SUNDAY. WINDS ON THE FRONT END OF THE SYSTEM WILL BE NORTHEAST INITIALLY UP TO 15 TO 20 KTS BUT WILL VEER AROUND THROUGH THE WEEKEND AND LIGHTEN TO 10 KTS OR SO AS GRADIENT RELAXES. BY SATURDAY EVENING WINDS WILL BE VERY LIGHT OUT OF THE E-NE AND BY SUNDAY A RETURN FLOW WILL SET UP AS WINDS VEER AROUND TO THE SOUTH REMAINING 10 KTS OR LESS. SEAS WILL JUST BE COMING DOWN FROM NEAR SCA CONDITIONS SAT MORNING IN OUTER WATERS AND WILL CONTINUE TO SUBSIDE THROUGH THE WEEKEND AS THEY VEER AROUND FROM NORTHEAST TO SOUTHEAST AND LIGHTEN. BY SUNDAY SEAS WILL BE 3 FT OR LESS. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 3 AM FRIDAY...A MORE SUMMER LIKE PATTERN WILL BE SETTING UP THROUGH NEXT WEEK AS RETURN FLOW PERSISTS AROUND BERMUDA HIGH PRESSURE. WINDS WILL REMAIN SOUTHERLY AROUND 10 KTS OR SO. WINDS AND SEAS WILL SPIKE UP NEAR SHORE IN FAIRLY POTENT SEA BREEZE EACH AFTERNOON...BUT OTHERWISE EXPECT SEAS 3 FT OR LESS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR AMZ256. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR AMZ250- 252. && $$ NEAR TERM...REK/TRA SHORT TERM... LONG TERM... AVIATION...BJR MARINE...REK/TRA
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1235 PM EDT FRI APR 5 2013 .SYNOPSIS... LOW PRESSURE SYSTEM JUST OFF THE NORTH CAROLINA COAST WILL CONTINUE TO LIFT OFF TO THE NORTHEAST AWAY FROM THE AREA THROUGH TODAY. HIGH PRESSURE WILL BUILD IN BEHIND THIS STORM SYSTEM... BRINGING A WARMING TREND AND SPRING-LIKE TEMPERATURES THROUGH NEXT WEEK. A MORE SUMMER-LIKE PATTERN SETS UP THROUGH MID WEEK AS BERMUDA HIGH PRESSURE DOMINATES BEFORE A COLD FRONT APPROACHES FROM THE WEST TOWARD LATE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 12:30 PM FRIDAY...OTHER THAN FOR GEORGETOWN COUNTY THE LATEST GUIDANCE AND RADAR LOOPS SUGGEST THAT PRECIP HAS ENDED FOR THE DAY. HAVE ALREADY CUT BACK ON POPS WITH THE LATEST ISSUANCES...AND WILL LIKELY MAY DROP POPS COMPLETELY WITH THE NEXT FORECAST PACKAGE. PREVIOUS DISCUSSION FOLLOWS: AN UPPER LEVEL DISTURBANCE MOVING RAPIDLY NORTH THROUGH GEORGIA AND NOW SOUTH CAROLINA HAS PRODUCED AN IMPRESSIVE AREA OF SHOWERS AND THUNDERSTORMS EXTENDING FROM GEORGETOWN SC SOUTH BACK INTO WAYCROSS AND AMERICUS GA VICINITY. THIS CONVECTION IS ELEVATED WITH THE LIFTING PARCEL LEVEL PROBABLY IN THE VICINITY OF 10000 FT AGL OR 700 MB. LATEST RUC ANALYSIS SHOWS LAPSE RATES IN THE 700-500 MB LAYER ARE EXCEEDING 7C/KM...AND FORECAST SOUNDINGS FROM VIRTUALLY ANY MODEL SHOW STEEP LAPSE RATES CONTINUING FOR AT LEAST ANOTHER 100 MB HIGHER IN THE ATMOSPHERE. I HAVE INCREASED POPS MAINLY ALONG THE SC COAST AND OFFSHORE FOR THE MORNING HOURS TO ACCOUNT FOR THIS ACTIVITY. FORTUNATELY THERE IS NO SEVERE WEATHER THREAT OWNING TO THE DEEP FRONTAL INVERSION BELOW THE STORMS AND SMALL CAPE VALUES ALOFT LIMITING POTENTIAL HAIL PRODUCTION. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... SURFACE LOW PRESSURE MOVED ALMOST DIRECTLY OVER ILM AROUND MIDNIGHT. NOW THAT THE LOW IS RACING NORTHEAST ACROSS EXTREME EASTERN NC COOL AIR HAS RUSHED DOWN TO THE CAPE FEAR AND GRAND STRAND BEACHES. LOW STRATUS CLOUDS WILL BE VERY TOUGH TO ERODE TODAY...AND IN FACT MODELS SUGGEST A SOLID GRAY OVERCAST WILL PERSIST THROUGH THE MORNING HOURS...RELUCTANTLY LIFTING INTO A SCT-BKN STRATOCUMULUS DECK SOMETIME IN THE 11 AM TO 2 PM PERIOD. IT APPEARS THE NAM HAS A BETTER HANDLE ON THE LATER CLOUD BURNOFF THAN THE GFS...THEREFORE MY FORECAST HIGHS ARE CLOSE THE NAM AND RANGE FROM THE UPPER 50S NEAR THE COAST TO AROUND 60 INLAND...10-13 DEGREES BELOW NORMAL. OF MORE IMMEDIATE CONCERN IS A CLUSTER OF THUNDERSTORMS ACROSS SOUTHERN GEORGIA ASSOCIATED WITH AN 500 MB VORT MAX ROTATING NORTHEASTWARD AROUND THE MAIN UPPER LOW STILL BACK ON THE MISSISSIPPI-ALABAMA BORDER. THIS CONVECTION APPEARS TO BE BASED AROUND 700 MB AND IS TAKING ADVANTAGE OF STEEPENING LAPSE RATES IN THE 700-400 MB LAYER AS COLD AIR WITH THE UPPER LOW ADVECTS ACROSS THE SOUTHEAST. IT IS POSSIBLE THESE SHOWERS AND THUNDERSTORMS WILL AFFECT COASTAL SOUTH CAROLINA LATER THIS MORNING...WHERE I HAVE A 30-40 PERCENT POP IN THE FORECAST. POPS ELSEWHERE ARE IN THE 10-20 PERCENT RANGE HEDGING FOR ANY EXPANSION IN THIS AREA OF ELEVATED CONVECTION. THE AFOREMENTIONED UPPER LOW WILL MOVE EAST ACROSS ALABAMA AND GEORGIA THIS MORNING...THEN INTO SOUTH CAROLINA BY MID AFTERNOON. LOW AND MID CLOUDS MAY CONTINUE ALONG THE COAST INTO THE EVENING HOURS BUT CLEARING SKIES SHOULD DEVELOP FROM WEST TO EAST AS THE UPPER LOW MOVES ACROSS. A NEW AREA OF SURFACE LOW PRESSURE WILL DEVELOP WELL OFF THE GA/SC COAST LATE THIS AFTERNOON IN ADVANCE OF THE UPPER SYSTEM. THIS NEW LOW SHOULD REMAIN TOO FAR AWAY FOR ANY DIRECT IMPACTS ON OUR AREA...BUT NORTHERLY FLOW BEHIND THIS LOW WILL HELP MAINLY A CHILLY AIRMASS ACROSS THE CAROLINAS TONIGHT WITH LOWS FALLING TO 40-45...A FEW DEGREES BELOW NORMAL. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN OVER THE SOUTHEAST THROUGH THE WEEKEND. A COOLER NORTHERLY FLOW INITIALLY WILL WEAKEN AND BECOME LIGHT AS IT VEERS AROUND THROUGH SAT NIGHT AS CENTER OF HIGH SHIFTS CLOSER OVERHEAD AND THEN OFF SHORE BY MORNING. THE MAX CAA WILL CUT OFF EARLY SATURDAY AS 850 TEMPS DROP CLOSE TO 3C. EXPECT AFTERNOON HIGHS TO ONCE AGAIN REMAIN BELOW NORMAL REACHING INTO THE LOW TO MID 60S. CALM WINDS AND CLEAR SKIES SATURDAY NIGHT WILL PROVIDE MORE IDEAL RADIATIONAL COOLING CONDITIONS WITH TEMPS DROPPING INTO THE LOWER END OF THE 40S MOST PLACES...BUT SLIGHTLY WARMER AT THE BEACHES. BY SUNDAY A RETURN FLOW WILL SET UP WITH LIGHT SOUTHERLY WINDS BEGINNING A WARMING TREND INTO NEXT WEEK. TEMPS WILL APPROACH NORMAL VALUES FOR THIS TIME OF YEAR WITH HIGH TEMPS JUST REACHING INTO THE 70S UNDER PLENTY OF SUNSHINE. OVERALL A BEAUTIFUL WEEKEND WITH LOTS OF SPRING SUNSHINE BUT SLIGHTLY COOLER TEMPS. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 3 AM FRIDAY...HEADING INTO A MORE SUMMER LIKE PATTERN FOR THIS TIME OF YEAR. BERMUDA HIGH PRESSURE WITH A WARMER MOISTER SOUTHERLY RETURN FLOW THROUGH THE PERIOD. A DEEP RIDGE BUILDS ALOFT WITH HEIGHT RISES PEAKING MID WEEK UP CLOSE TO 585 DM. AS THE MID TO UPPER RIDGE BUILDS UP THE EAST COAST A DEEPENING TROUGH WILL DIG DOWN THROUGH THE MID WEST. ALTHOUGH THE RIDGE HOLDS ON TIGHT THROUGH MUCH OF THE WORK WEEK...THE TROUGH FINALLY MOVES EAST TOWARD THE AREA PUSHING A COLD FRONT OUR WAY BY THURS NIGHT INTO FRIDAY. MODELS HAVE PUSHED THE TIMING BACK A BIT AND THEREFORE LOOKS LIKE NICE WEATHER WILL HOLD OUT THROUGH THURSDAY. OVERALL A RAIN FREE WEEK WITH A SHARP WARMING TREND BRINGING TEMPS TO SEVERAL DEGREES ABOVE NORMAL WITH HIGH TEMPS FLIRTING WITH 80 OR SLIGHTLY ABOVE IN PLACES AND MIN TEMPS CLOSE TO WHAT WE HAVE BEEN EXPERIENCING FOR HIGH TEMPS LATELY. THE COOLER OCEAN TEMPS WILL MAXIMIZE THE DIFFERENTIAL HEATING ALLOWING FOR A STRONG SEA BREEZE TO CARRY FAR INLAND MOST AFTERNOONS. THIS WILL BRING COOLER AIR INLAND BUT WILL ALSO KEEP THE BEACHES MUCH COOLER. THE SEA BREEZE WILL ALSO PROVIDE A FOCAL POINT FOR ENOUGH CONVERGENCE TO PRODUCE CU EACH AFTERNOON AND MAY SEE SOME PASSING HIGH CLOUDS BUT OTHERWISE SHOULD SEE A GOOD DEAL OF SUNSHINE THROUGH THE WEEK WITH ANY PCP HOLDING OFF UNTIL LATE THURS INTO FRIDAY. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AS OF 12Z...RADAR INDICATES SOME SHOWER ACTIVITY NEAR KMYR/KCRE IS MOVING NORTHEAST UP THE CAROLINA COAST. MOST OF THE ACTIVITY IS REMAINING OFFSHORE...AND DO NOT EXPECT ANY PCPN FOR KILM ATTM. WIDESPREAD IFR CIGS ARE BEING REPORTED AT ALL TERMS THIS MORNING. GFS AND NAM GUIDANCE IN GOOD AGREEMENT THAT IFR WILL PERSIST FOR MUCH OF THE MORNING...ESPECIALLY ALONG THE COAST. KFLO/KLBT CIGS WILL LIKELY LIFT ABOVE 1KFT BY MID TO LATE MORNING...WHEREAS KILM/KMYR/KCRE COULD SEE IFR CONDITIONS LINGER UNTIL MIDDAY. ONCE THE STRATUS FINALLY LIFTS...EXPECT MVFR IN THE EARLY AFTERNOON TO BECOME VFR BY LATE AFTERNOON THROUGH THE END OF THE TAF PERIOD. NORTHWEST WINDS AOB 12 KTS THIS MORNING WILL VEER TO THE NORTH LATER TODAY...REMAINING AOB 10 KTS. THE SKIES WILL CLEAR OUT OVERNIGHT AS AN UPPER LOW PUSHES THROUGH THE CAROLINAS. EXTENDED OUTLOOK...VFR EXPECTED SATURDAY THROUGH TUESDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 12:30 PM FRIDAY...LATEST OBS AND GUIDANCE SUGGEST THAT WE CAN DROP SMALL CRAFT ADVISORIES EARLY FOR ALL THE REMAINING COASTAL WATERS. IT IS LIKELY WE ARE NOW ONLY SEEING 6 FOOTERS OVER THE OUTER EDGES OF THE COASTAL WATERS. PREVIOUS DISCUSSION FOLLOWS: TWO CHANGES HAVE BEEN MADE TO THE MARINE FORECAST THIS MORNING. THE FIRST IS TO INCREASE SHOWER AND T-STORM CHANCES THROUGH THE MORNING HOURS AS THE WILMINGTON AND CHARLESTON RADARS ARE SHOWING AN IMPRESSIVE AREA OF SHOWERS AND STORMS MOVING RAPIDLY NORTHEAST ALONG THE COAST. THE SOUTH CAROLINA COASTAL WATERS WILL BE MOST STRONGLY AFFECTED BY THIS ACTIVITY...WHICH SHOULD TAPER OFF BY NOON. ALSO...OBSERVED WIND SPEEDS ARE ABOUT 5 KNOTS STRONGER THAN EXPECTED ACROSS THE WATERS NORTH OF CAPE FEAR...WHERE RECENTLY GUSTS AT BOTH WRIGHTSVILLE BEACH AND THE FRYING PAN SHOALS BUOY OFFSHORE HAVE BEEN AROUND 20 KNOTS. NO OTHER SIGNIFICANT CHANGES HAVE BEEN MADE. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... SURFACE LOW PRESSURE MOVED OVER WILMINGTON AROUND MIDNIGHT AND IS NOW RACING NORTHEAST ACROSS THE PAMLICO SOUND. NORTHWESTERLY WINDS BEHIND THIS LOW HAVE PUSHED THE COLD FRONT A CONSIDERABLE DISTANCE FROM SHORE...AND COOL NORTHWEST TO NORTH WINDS SHOULD CONTINUE THROUGH THE DAY. STRONG WINDS YESTERDAY STILL HAVE THE SEA STATE QUITE AGITATED AND IT WILL TAKE MOST OF THE DAY FOR SEAS TO DECAY BELOW 6 FEET. FOR THIS REASON THE SMALL CRAFT ADVISORY WILL REMAIN POSTED INTO THE AFTERNOON HOURS FOR THE SC COASTAL WATERS...AND UNTIL THIS EVENING FOR THE NC WATERS. AN APPROACHING UPPER LEVEL LOW WILL INDUCE A NEW LOW TO DEVELOP WELL OFF THE SC COAST LATE THIS AFTERNOON. WHILE THIS NEW LOW WILL HAVE NO DIRECT IMPACTS LOCALLY...IT WILL HELP TO ENHANCE THE NORTHERLY WINDS SOMEWHAT WITH WIND SPEEDS PERHAPS ECLIPSING 15 KNOTS OVERNIGHT...ESPECIALLY AWAY FROM SHORE. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN INTO THE LOCAL WATERS THROUGH SATURDAY BEFORE SHIFTING CLOSER OVERHEAD SAT NIGHT AND THEN OFF SHORE THROUGH SUNDAY. WINDS ON THE FRONT END OF THE SYSTEM WILL BE NORTHEAST INITIALLY UP TO 15 TO 20 KTS BUT WILL VEER AROUND THROUGH THE WEEKEND AND LIGHTEN TO 10 KTS OR SO AS GRADIENT RELAXES. BY SATURDAY EVENING WINDS WILL BE VERY LIGHT OUT OF THE E-NE AND BY SUNDAY A RETURN FLOW WILL SET UP AS WINDS VEER AROUND TO THE SOUTH REMAINING 10 KTS OR LESS. SEAS WILL JUST BE COMING DOWN FROM NEAR SCA CONDITIONS SAT MORNING IN OUTER WATERS AND WILL CONTINUE TO SUBSIDE THROUGH THE WEEKEND AS THEY VEER AROUND FROM NORTHEAST TO SOUTHEAST AND LIGHTEN. BY SUNDAY SEAS WILL BE 3 FT OR LESS. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 3 AM FRIDAY...A MORE SUMMER LIKE PATTERN WILL BE SETTING UP THROUGH NEXT WEEK AS RETURN FLOW PERSISTS AROUND BERMUDA HIGH PRESSURE. WINDS WILL REMAIN SOUTHERLY AROUND 10 KTS OR SO. WINDS AND SEAS WILL SPIKE UP NEAR SHORE IN FAIRLY POTENT SEA BREEZE EACH AFTERNOON...BUT OTHERWISE EXPECT SEAS 3 FT OR LESS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR AMZ256. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR AMZ250- 252. && $$ NEAR TERM...TRA SHORT TERM...REK LONG TERM... AVIATION...BJR MARINE...REK/TRA
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
738 AM EDT FRI APR 5 2013 .SYNOPSIS... LOW PRESSURE SYSTEM JUST OFF THE NORTH CAROLINA COAST WILL CONTINUE TO LIFT OFF TO THE NORTHEAST AWAY FROM THE AREA THROUGH TODAY. HIGH PRESSURE WILL BUILD IN BEHIND THIS STORM SYSTEM... BRINGING A WARMING TREND AND SPRING-LIKE TEMPERATURES THROUGH NEXT WEEK. A MORE SUMMER-LIKE PATTERN SETS UP THROUGH MID WEEK AS BERMUDA HIGH PRESSURE DOMINATES BEFORE A COLD FRONT APPROACHES FROM THE WEST TOWARD LATE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM FRIDAY...AN UPPER LEVEL DISTURBANCE MOVING RAPIDLY NORTH THROUGH GEORGIA AND NOW SOUTH CAROLINA HAS PRODUCED AN IMPRESSIVE AREA OF SHOWERS AND THUNDERSTORMS EXTENDING FROM GEORGETOWN SC SOUTH BACK INTO WAYCROSS AND AMERICUS GA VICINITY. THIS CONVECTION IS ELEVATED WITH THE LIFTING PARCEL LEVEL PROBABLY IN THE VICINITY OF 10000 FT AGL OR 700 MB. LATEST RUC ANALYSIS SHOWS LAPSE RATES IN THE 700-500 MB LAYER ARE EXCEEDING 7C/KM...AND FORECAST SOUNDINGS FROM VIRTUALLY ANY MODEL SHOW STEEP LAPSE RATES CONTINUING FOR AT LEAST ANOTHER 100 MB HIGHER IN THE ATMOSPHERE. I HAVE INCREASED POPS MAINLY ALONG THE SC COAST AND OFFSHORE FOR THE MORNING HOURS TO ACCOUNT FOR THIS ACTIVITY. FORTUNATELY THERE IS NO SEVERE WEATHER THREAT OWNING TO THE DEEP FRONTAL INVERSION BELOW THE STORMS AND SMALL CAPE VALUES ALOFT LIMITING POTENTIAL HAIL PRODUCTION. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... SURFACE LOW PRESSURE MOVED ALMOST DIRECTLY OVER ILM AROUND MIDNIGHT. NOW THAT THE LOW IS RACING NORTHEAST ACROSS EXTREME EASTERN NC COOL AIR HAS RUSHED DOWN TO THE CAPE FEAR AND GRAND STRAND BEACHES. LOW STRATUS CLOUDS WILL BE VERY TOUGH TO ERODE TODAY...AND IN FACT MODELS SUGGEST A SOLID GRAY OVERCAST WILL PERSIST THROUGH THE MORNING HOURS...RELUCTANTLY LIFTING INTO A SCT-BKN STRATOCUMULUS DECK SOMETIME IN THE 11 AM TO 2 PM PERIOD. IT APPEARS THE NAM HAS A BETTER HANDLE ON THE LATER CLOUD BURNOFF THAN THE GFS...THEREFORE MY FORECAST HIGHS ARE CLOSE THE NAM AND RANGE FROM THE UPPER 50S NEAR THE COAST TO AROUND 60 INLAND...10-13 DEGREES BELOW NORMAL. OF MORE IMMEDIATE CONCERN IS A CLUSTER OF THUNDERSTORMS ACROSS SOUTHERN GEORGIA ASSOCIATED WITH AN 500 MB VORT MAX ROTATING NORTHEASTWARD AROUND THE MAIN UPPER LOW STILL BACK ON THE MISSISSIPPI-ALABAMA BORDER. THIS CONVECTION APPEARS TO BE BASED AROUND 700 MB AND IS TAKING ADVANTAGE OF STEEPENING LAPSE RATES IN THE 700-400 MB LAYER AS COLD AIR WITH THE UPPER LOW ADVECTS ACROSS THE SOUTHEAST. IT IS POSSIBLE THESE SHOWERS AND THUNDERSTORMS WILL AFFECT COASTAL SOUTH CAROLINA LATER THIS MORNING...WHERE I HAVE A 30-40 PERCENT POP IN THE FORECAST. POPS ELSEWHERE ARE IN THE 10-20 PERCENT RANGE HEDGING FOR ANY EXPANSION IN THIS AREA OF ELEVATED CONVECTION. THE AFOREMENTIONED UPPER LOW WILL MOVE EAST ACROSS ALABAMA AND GEORGIA THIS MORNING...THEN INTO SOUTH CAROLINA BY MID AFTERNOON. LOW AND MID CLOUDS MAY CONTINUE ALONG THE COAST INTO THE EVENING HOURS BUT CLEARING SKIES SHOULD DEVELOP FROM WEST TO EAST AS THE UPPER LOW MOVES ACROSS. A NEW AREA OF SURFACE LOW PRESSURE WILL DEVELOP WELL OFF THE GA/SC COAST LATE THIS AFTERNOON IN ADVANCE OF THE UPPER SYSTEM. THIS NEW LOW SHOULD REMAIN TOO FAR AWAY FOR ANY DIRECT IMPACTS ON OUR AREA...BUT NORTHERLY FLOW BEHIND THIS LOW WILL HELP MAINLY A CHILLY AIRMASS ACROSS THE CAROLINAS TONIGHT WITH LOWS FALLING TO 40-45...A FEW DEGREES BELOW NORMAL. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN OVER THE SOUTHEAST THROUGH THE WEEKEND. A COOLER NORTHERLY FLOW INITIALLY WILL WEAKEN AND BECOME LIGHT AS IT VEERS AROUND THROUGH SAT NIGHT AS CENTER OF HIGH SHIFTS CLOSER OVERHEAD AND THEN OFF SHORE BY MORNING. THE MAX CAA WILL CUT OFF EARLY SATURDAY AS 850 TEMPS DROP CLOSE TO 3C. EXPECT AFTERNOON HIGHS TO ONCE AGAIN REMAIN BELOW NORMAL REACHING INTO THE LOW TO MID 60S. CALM WINDS AND CLEAR SKIES SATURDAY NIGHT WILL PROVIDE MORE IDEAL RADIATIONAL COOLING CONDITIONS WITH TEMPS DROPPING INTO THE LOWER END OF THE 40S MOST PLACES...BUT SLIGHTLY WARMER AT THE BEACHES. BY SUNDAY A RETURN FLOW WILL SET UP WITH LIGHT SOUTHERLY WINDS BEGINNING A WARMING TREND INTO NEXT WEEK. TEMPS WILL APPROACH NORMAL VALUES FOR THIS TIME OF YEAR WITH HIGH TEMPS JUST REACHING INTO THE 70S UNDER PLENTY OF SUNSHINE. OVERALL A BEAUTIFUL WEEKEND WITH LOTS OF SPRING SUNSHINE BUT SLIGHTLY COOLER TEMPS. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 3 AM FRIDAY...HEADING INTO A MORE SUMMER LIKE PATTERN FOR THIS TIME OF YEAR. BERMUDA HIGH PRESSURE WITH A WARMER MOISTER SOUTHERLY RETURN FLOW THROUGH THE PERIOD. A DEEP RIDGE BUILDS ALOFT WITH HEIGHT RISES PEAKING MID WEEK UP CLOSE TO 585 DM. AS THE MID TO UPPER RIDGE BUILDS UP THE EAST COAST A DEEPENING TROUGH WILL DIG DOWN THROUGH THE MID WEST. ALTHOUGH THE RIDGE HOLDS ON TIGHT THROUGH MUCH OF THE WORK WEEK...THE TROUGH FINALLY MOVES EAST TOWARD THE AREA PUSHING A COLD FRONT OUR WAY BY THURS NIGHT INTO FRIDAY. MODELS HAVE PUSHED THE TIMING BACK A BIT AND THEREFORE LOOKS LIKE NICE WEATHER WILL HOLD OUT THROUGH THURSDAY. OVERALL A RAIN FREE WEEK WITH A SHARP WARMING TREND BRINGING TEMPS TO SEVERAL DEGREES ABOVE NORMAL WITH HIGH TEMPS FLIRTING WITH 80 OR SLIGHTLY ABOVE IN PLACES AND MIN TEMPS CLOSE TO WHAT WE HAVE BEEN EXPERIENCING FOR HIGH TEMPS LATELY. THE COOLER OCEAN TEMPS WILL MAXIMIZE THE DIFFERENTIAL HEATING ALLOWING FOR A STRONG SEA BREEZE TO CARRY FAR INLAND MOST AFTERNOONS. THIS WILL BRING COOLER AIR INLAND BUT WILL ALSO KEEP THE BEACHES MUCH COOLER. THE SEA BREEZE WILL ALSO PROVIDE A FOCAL POINT FOR ENOUGH CONVERGENCE TO PRODUCE CU EACH AFTERNOON AND MAY SEE SOME PASSING HIGH CLOUDS BUT OTHERWISE SHOULD SEE A GOOD DEAL OF SUNSHINE THROUGH THE WEEK WITH ANY PCP HOLDING OFF UNTIL LATE THURS INTO FRIDAY. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... AS OF 12Z...RADAR INDICATES SOME SHOWER ACTIVITY NEAR KMYR/KCRE IS MOVING NORTHEAST UP THE CAROLINA COAST. MOST OF THE ACTIVITY IS REMAINING OFFSHORE...AND DO NOT EXPECT ANY PCPN FOR KILM ATTM. WIDESPREAD IFR CIGS ARE BEING REPORTED AT ALL TERMS THIS MORNING. GFS AND NAM GUIDANCE IN GOOD AGREEMENT THAT IFR WILL PERSIST FOR MUCH OF THE MORNING...ESPECIALLY ALONG THE COAST. KFLO/KLBT CIGS WILL LIKELY LIFT ABOVE 1KFT BY MID TO LATE MORNING...WHEREAS KILM/KMYR/KCRE COULD SEE IFR CONDITIONS LINGER UNTIL MIDDAY. ONCE THE STRATUS FINALLY LIFTS...EXPECT MVFR IN THE EARLY AFTERNOON TO BECOME VFR BY LATE AFTERNOON THROUGH THE END OF THE TAF PERIOD. NORTHWEST WINDS AOB 12 KTS THIS MORNING WILL VEER TO THE NORTH LATER TODAY...REMAINING AOB 10 KTS. THE SKIES WILL CLEAR OUT OVERNIGHT AS AN UPPER LOW PUSHES THROUGH THE CAROLINAS. EXTENDED OUTLOOK...VFR EXPECTED SATURDAY THROUGH TUESDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM FRIDAY...TWO CHANGES HAVE BEEN MADE TO THE MARINE FORECAST THIS MORNING. THE FIRST IS TO INCREASE SHOWER AND T-STORM CHANCES THROUGH THE MORNING HOURS AS THE WILMINGTON AND CHARLESTON RADARS ARE SHOWING AN IMPRESSIVE AREA OF SHOWERS AND STORMS MOVING RAPIDLY NORTHEAST ALONG THE COAST. THE SOUTH CAROLINA COASTAL WATERS WILL BE MOST STRONGLY AFFECTED BY THIS ACTIVITY...WHICH SHOULD TAPER OFF BY NOON. ALSO...OBSERVED WIND SPEEDS ARE ABOUT 5 KNOTS STRONGER THAN EXPECTED ACROSS THE WATERS NORTH OF CAPE FEAR...WHERE RECENTLY GUSTS AT BOTH WRIGHTSVILLE BEACH AND THE FRYING PAN SHOALS BUOY OFFSHORE HAVE BEEN AROUND 20 KNOTS. NO OTHER SIGNIFICANT CHANGES HAVE BEEN MADE. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... SURFACE LOW PRESSURE MOVED OVER WILMINGTON AROUND MIDNIGHT AND IS NOW RACING NORTHEAST ACROSS THE PAMLICO SOUND. NORTHWESTERLY WINDS BEHIND THIS LOW HAVE PUSHED THE COLD FRONT A CONSIDERABLE DISTANCE FROM SHORE...AND COOL NORTHWEST TO NORTH WINDS SHOULD CONTINUE THROUGH THE DAY. STRONG WINDS YESTERDAY STILL HAVE THE SEA STATE QUITE AGITATED AND IT WILL TAKE MOST OF THE DAY FOR SEAS TO DECAY BELOW 6 FEET. FOR THIS REASON THE SMALL CRAFT ADVISORY WILL REMAIN POSTED INTO THE AFTERNOON HOURS FOR THE SC COASTAL WATERS...AND UNTIL THIS EVENING FOR THE NC WATERS. AN APPROACHING UPPER LEVEL LOW WILL INDUCE A NEW LOW TO DEVELOP WELL OFF THE SC COAST LATE THIS AFTERNOON. WHILE THIS NEW LOW WILL HAVE NO DIRECT IMPACTS LOCALLY...IT WILL HELP TO ENHANCE THE NORTHERLY WINDS SOMEWHAT WITH WIND SPEEDS PERHAPS ECLIPSING 15 KNOTS OVERNIGHT...ESPECIALLY AWAY FROM SHORE. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN INTO THE LOCAL WATERS THROUGH SATURDAY BEFORE SHIFTING CLOSER OVERHEAD SAT NIGHT AND THEN OFF SHORE THROUGH SUNDAY. WINDS ON THE FRONT END OF THE SYSTEM WILL BE NORTHEAST INITIALLY UP TO 15 TO 20 KTS BUT WILL VEER AROUND THROUGH THE WEEKEND AND LIGHTEN TO 10 KTS OR SO AS GRADIENT RELAXES. BY SATURDAY EVENING WINDS WILL BE VERY LIGHT OUT OF THE E-NE AND BY SUNDAY A RETURN FLOW WILL SET UP AS WINDS VEER AROUND TO THE SOUTH REMAINING 10 KTS OR LESS. SEAS WILL JUST BE COMING DOWN FROM NEAR SCA CONDITIONS SAT MORNING IN OUTER WATERS AND WILL CONTINUE TO SUBSIDE THROUGH THE WEEKEND AS THEY VEER AROUND FROM NORTHEAST TO SOUTHEAST AND LIGHTEN. BY SUNDAY SEAS WILL BE 3 FT OR LESS. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 3 AM FRIDAY...A MORE SUMMER LIKE PATTERN WILL BE SETTING UP THROUGH NEXT WEEK AS RETURN FLOW PERSISTS AROUND BERMUDA HIGH PRESSURE. WINDS WILL REMAIN SOUTHERLY AROUND 10 KTS OR SO. WINDS AND SEAS WILL SPIKE UP NEAR SHORE IN FAIRLY POTENT SEA BREEZE EACH AFTERNOON...BUT OTHERWISE EXPECT SEAS 3 FT OR LESS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR AMZ256. SMALL CRAFT ADVISORY UNTIL NOON EDT TODAY FOR AMZ254. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR AMZ250- 252. && $$ NEAR TERM...TRA SHORT TERM...RGZ LONG TERM...RGZ AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
626 AM EDT FRI APR 5 2013 .SYNOPSIS... LOW PRESSURE SYSTEM JUST OFF THE NORTH CAROLINA COAST WILL CONTINUE TO LIFT OFF TO THE NORTHEAST AWAY FROM THE AREA THROUGH TODAY. HIGH PRESSURE WILL BUILD IN BEHIND THIS STORM SYSTEM... BRINGING A WARMING TREND AND SPRING-LIKE TEMPERATURES THROUGH NEXT WEEK. A MORE SUMMER-LIKE PATTERN SETS UP THROUGH MID WEEK AS BERMUDA HIGH PRESSURE DOMINATES BEFORE A COLD FRONT APPROACHES FROM THE WEST TOWARD LATE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM FRIDAY...AN UPPER LEVEL DISTURBANCE MOVING RAPIDLY NORTH THROUGH GEORGIA AND NOW SOUTH CAROLINA HAS PRODUCED AN IMPRESSIVE AREA OF SHOWERS AND THUNDERSTORMS EXTENDING FROM GEORGETOWN SC SOUTH BACK INTO WAYCROSS AND AMERICUS GA VICINITY. THIS CONVECTION IS ELEVATED WITH THE LIFTING PARCEL LEVEL PROBABLY IN THE VICINITY OF 10000 FT AGL OR 700 MB. LATEST RUC ANALYSIS SHOWS LAPSE RATES IN THE 700-500 MB LAYER ARE EXCEEDING 7C/KM...AND FORECAST SOUNDINGS FROM VIRTUALLY ANY MODEL SHOW STEEP LAPSE RATES CONTINUING FOR AT LEAST ANOTHER 100 MB HIGHER IN THE ATMOSPHERE. I HAVE INCREASED POPS MAINLY ALONG THE SC COAST AND OFFSHORE FOR THE MORNING HOURS TO ACCOUNT FOR THIS ACTIVITY. FORTUNATELY THERE IS NO SEVERE WEATHER THREAT OWNING TO THE DEEP FRONTAL INVERSION BELOW THE STORMS AND SMALL CAPE VALUES ALOFT LIMITING POTENTIAL HAIL PRODUCTION. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... SURFACE LOW PRESSURE MOVED ALMOST DIRECTLY OVER ILM AROUND MIDNIGHT. NOW THAT THE LOW IS RACING NORTHEAST ACROSS EXTREME EASTERN NC COOL AIR HAS RUSHED DOWN TO THE CAPE FEAR AND GRAND STRAND BEACHES. LOW STRATUS CLOUDS WILL BE VERY TOUGH TO ERODE TODAY...AND IN FACT MODELS SUGGEST A SOLID GRAY OVERCAST WILL PERSIST THROUGH THE MORNING HOURS...RELUCTANTLY LIFTING INTO A SCT-BKN STRATOCUMULUS DECK SOMETIME IN THE 11 AM TO 2 PM PERIOD. IT APPEARS THE NAM HAS A BETTER HANDLE ON THE LATER CLOUD BURNOFF THAN THE GFS...THEREFORE MY FORECAST HIGHS ARE CLOSE THE NAM AND RANGE FROM THE UPPER 50S NEAR THE COAST TO AROUND 60 INLAND...10-13 DEGREES BELOW NORMAL. OF MORE IMMEDIATE CONCERN IS A CLUSTER OF THUNDERSTORMS ACROSS SOUTHERN GEORGIA ASSOCIATED WITH AN 500 MB VORT MAX ROTATING NORTHEASTWARD AROUND THE MAIN UPPER LOW STILL BACK ON THE MISSISSIPPI-ALABAMA BORDER. THIS CONVECTION APPEARS TO BE BASED AROUND 700 MB AND IS TAKING ADVANTAGE OF STEEPENING LAPSE RATES IN THE 700-400 MB LAYER AS COLD AIR WITH THE UPPER LOW ADVECTS ACROSS THE SOUTHEAST. IT IS POSSIBLE THESE SHOWERS AND THUNDERSTORMS WILL AFFECT COASTAL SOUTH CAROLINA LATER THIS MORNING...WHERE I HAVE A 30-40 PERCENT POP IN THE FORECAST. POPS ELSEWHERE ARE IN THE 10-20 PERCENT RANGE HEDGING FOR ANY EXPANSION IN THIS AREA OF ELEVATED CONVECTION. THE AFOREMENTIONED UPPER LOW WILL MOVE EAST ACROSS ALABAMA AND GEORGIA THIS MORNING...THEN INTO SOUTH CAROLINA BY MID AFTERNOON. LOW AND MID CLOUDS MAY CONTINUE ALONG THE COAST INTO THE EVENING HOURS BUT CLEARING SKIES SHOULD DEVELOP FROM WEST TO EAST AS THE UPPER LOW MOVES ACROSS. A NEW AREA OF SURFACE LOW PRESSURE WILL DEVELOP WELL OFF THE GA/SC COAST LATE THIS AFTERNOON IN ADVANCE OF THE UPPER SYSTEM. THIS NEW LOW SHOULD REMAIN TOO FAR AWAY FOR ANY DIRECT IMPACTS ON OUR AREA...BUT NORTHERLY FLOW BEHIND THIS LOW WILL HELP MAINLY A CHILLY AIRMASS ACROSS THE CAROLINAS TONIGHT WITH LOWS FALLING TO 40-45...A FEW DEGREES BELOW NORMAL. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN OVER THE SOUTHEAST THROUGH THE WEEKEND. A COOLER NORTHERLY FLOW INITIALLY WILL WEAKEN AND BECOME LIGHT AS IT VEERS AROUND THROUGH SAT NIGHT AS CENTER OF HIGH SHIFTS CLOSER OVERHEAD AND THEN OFF SHORE BY MORNING. THE MAX CAA WILL CUT OFF EARLY SATURDAY AS 850 TEMPS DROP CLOSE TO 3C. EXPECT AFTERNOON HIGHS TO ONCE AGAIN REMAIN BELOW NORMAL REACHING INTO THE LOW TO MID 60S. CALM WINDS AND CLEAR SKIES SATURDAY NIGHT WILL PROVIDE MORE IDEAL RADIATIONAL COOLING CONDITIONS WITH TEMPS DROPPING INTO THE LOWER END OF THE 40S MOST PLACES...BUT SLIGHTLY WARMER AT THE BEACHES. BY SUNDAY A RETURN FLOW WILL SET UP WITH LIGHT SOUTHERLY WINDS BEGINNING A WARMING TREND INTO NEXT WEEK. TEMPS WILL APPROACH NORMAL VALUES FOR THIS TIME OF YEAR WITH HIGH TEMPS JUST REACHING INTO THE 70S UNDER PLENTY OF SUNSHINE. OVERALL A BEAUTIFUL WEEKEND WITH LOTS OF SPRING SUNSHINE BUT SLIGHTLY COOLER TEMPS. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 3 AM FRIDAY...HEADING INTO A MORE SUMMER LIKE PATTERN FOR THIS TIME OF YEAR. BERMUDA HIGH PRESSURE WITH A WARMER MOISTER SOUTHERLY RETURN FLOW THROUGH THE PERIOD. A DEEP RIDGE BUILDS ALOFT WITH HEIGHT RISES PEAKING MID WEEK UP CLOSE TO 585 DM. AS THE MID TO UPPER RIDGE BUILDS UP THE EAST COAST A DEEPENING TROUGH WILL DIG DOWN THROUGH THE MID WEST. ALTHOUGH THE RIDGE HOLDS ON TIGHT THROUGH MUCH OF THE WORK WEEK...THE TROUGH FINALLY MOVES EAST TOWARD THE AREA PUSHING A COLD FRONT OUR WAY BY THURS NIGHT INTO FRIDAY. MODELS HAVE PUSHED THE TIMING BACK A BIT AND THEREFORE LOOKS LIKE NICE WEATHER WILL HOLD OUT THROUGH THURSDAY. OVERALL A RAIN FREE WEEK WITH A SHARP WARMING TREND BRINGING TEMPS TO SEVERAL DEGREES ABOVE NORMAL WITH HIGH TEMPS FLIRTING WITH 80 OR SLIGHTLY ABOVE IN PLACES AND MIN TEMPS CLOSE TO WHAT WE HAVE BEEN EXPERIENCING FOR HIGH TEMPS LATELY. THE COOLER OCEAN TEMPS WILL MAXIMIZE THE DIFFERENTIAL HEATING ALLOWING FOR A STRONG SEA BREEZE TO CARRY FAR INLAND MOST AFTERNOONS. THIS WILL BRING COOLER AIR INLAND BUT WILL ALSO KEEP THE BEACHES MUCH COOLER. THE SEA BREEZE WILL ALSO PROVIDE A FOCAL POINT FOR ENOUGH CONVERGENCE TO PRODUCE CU EACH AFTERNOON AND MAY SEE SOME PASSING HIGH CLOUDS BUT OTHERWISE SHOULD SEE A GOOD DEAL OF SUNSHINE THROUGH THE WEEK WITH ANY PCP HOLDING OFF UNTIL LATE THURS INTO FRIDAY. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AS OF 06Z...THE SURFACE LOW MOVED ESSENTIALLY OVER ILM AROUND MIDNIGHT AND IS NOW MOVING NE TOWARD THE NC OUTER BANKS. WINDS HAVE SHIFTED TO NW ACROSS THE AREA AND SHOULD VEER MORE NORTHERLY AFTER DAYBREAK. SOLID IFR/LIFR CIGS ARE EXPECTED TO PREVAIL THROUGH MUCH OF THE MORNING HOURS. IFR/MVFR VSBYS DUE TO DZ SHOULD DISSIPATE BY 08Z AS THE CLOUD DEPTH THINS FROM ALOFT. CIGS WILL BE SLOW TO LIFT LATER TODAY...PERHAPS TAKING UNTIL 14Z INLAND AND 17Z AT THE COAST TO LIFT ABOVE 1000 FT AGL. VFR CIGS ARE ANTICIPATED EVERYWHERE BY MID AFTERNOON. AN UPPER LEVEL LOW WILL DRIFT OVER THE REGION EARLY IN THE EVENING...WITH NO FLIGHT CATEGORY CHANGES ANTICIPATED. NORTHERLY SFC WINDS AROUND 10 KNOTS WILL DIMINISH AFTER DARK. EXTENDED OUTLOOK...EXPECT VFR SATURDAY THROUGH TUESDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM FRIDAY...TWO CHANGES HAVE BEEN MADE TO THE MARINE FORECAST THIS MORNING. THE FIRST IS TO INCREASE SHOWER AND T-STORM CHANCES THROUGH THE MORNING HOURS AS THE WILMINGTON AND CHARLESTON RADARS ARE SHOWING AN IMPRESSIVE AREA OF SHOWERS AND STORMS MOVING RAPIDLY NORTHEAST ALONG THE COAST. THE SOUTH CAROLINA COASTAL WATERS WILL BE MOST STRONGLY AFFECTED BY THIS ACTIVITY...WHICH SHOULD TAPER OFF BY NOON. ALSO...OBSERVED WIND SPEEDS ARE ABOUT 5 KNOTS STRONGER THAN EXPECTED ACROSS THE WATERS NORTH OF CAPE FEAR...WHERE RECENTLY GUSTS AT BOTH WRIGHTSVILLE BEACH AND THE FRYING PAN SHOALS BUOY OFFSHORE HAVE BEEN AROUND 20 KNOTS. NO OTHER SIGNIFICANT CHANGES HAVE BEEN MADE. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... SURFACE LOW PRESSURE MOVED OVER WILMINGTON AROUND MIDNIGHT AND IS NOW RACING NORTHEAST ACROSS THE PAMLICO SOUND. NORTHWESTERLY WINDS BEHIND THIS LOW HAVE PUSHED THE COLD FRONT A CONSIDERABLE DISTANCE FROM SHORE...AND COOL NORTHWEST TO NORTH WINDS SHOULD CONTINUE THROUGH THE DAY. STRONG WINDS YESTERDAY STILL HAVE THE SEA STATE QUITE AGITATED AND IT WILL TAKE MOST OF THE DAY FOR SEAS TO DECAY BELOW 6 FEET. FOR THIS REASON THE SMALL CRAFT ADVISORY WILL REMAIN POSTED INTO THE AFTERNOON HOURS FOR THE SC COASTAL WATERS...AND UNTIL THIS EVENING FOR THE NC WATERS. AN APPROACHING UPPER LEVEL LOW WILL INDUCE A NEW LOW TO DEVELOP WELL OFF THE SC COAST LATE THIS AFTERNOON. WHILE THIS NEW LOW WILL HAVE NO DIRECT IMPACTS LOCALLY...IT WILL HELP TO ENHANCE THE NORTHERLY WINDS SOMEWHAT WITH WIND SPEEDS PERHAPS ECLIPSING 15 KNOTS OVERNIGHT...ESPECIALLY AWAY FROM SHORE. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN INTO THE LOCAL WATERS THROUGH SATURDAY BEFORE SHIFTING CLOSER OVERHEAD SAT NIGHT AND THEN OFF SHORE THROUGH SUNDAY. WINDS ON THE FRONT END OF THE SYSTEM WILL BE NORTHEAST INITIALLY UP TO 15 TO 20 KTS BUT WILL VEER AROUND THROUGH THE WEEKEND AND LIGHTEN TO 10 KTS OR SO AS GRADIENT RELAXES. BY SATURDAY EVENING WINDS WILL BE VERY LIGHT OUT OF THE E-NE AND BY SUNDAY A RETURN FLOW WILL SET UP AS WINDS VEER AROUND TO THE SOUTH REMAINING 10 KTS OR LESS. SEAS WILL JUST BE COMING DOWN FROM NEAR SCA CONDITIONS SAT MORNING IN OUTER WATERS AND WILL CONTINUE TO SUBSIDE THROUGH THE WEEKEND AS THEY VEER AROUND FROM NORTHEAST TO SOUTHEAST AND LIGHTEN. BY SUNDAY SEAS WILL BE 3 FT OR LESS. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 3 AM FRIDAY...A MORE SUMMER LIKE PATTERN WILL BE SETTING UP THROUGH NEXT WEEK AS RETURN FLOW PERSISTS AROUND BERMUDA HIGH PRESSURE. WINDS WILL REMAIN SOUTHERLY AROUND 10 KTS OR SO. WINDS AND SEAS WILL SPIKE UP NEAR SHORE IN FAIRLY POTENT SEA BREEZE EACH AFTERNOON...BUT OTHERWISE EXPECT SEAS 3 FT OR LESS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR AMZ256. SMALL CRAFT ADVISORY UNTIL NOON EDT TODAY FOR AMZ254. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR AMZ250- 252. && $$ NEAR TERM...TRA SHORT TERM...RGZ LONG TERM...RGZ AVIATION...TRA/DL
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
749 PM EDT SAT APR 6 2013 .SYNOPSIS... LOW PRESSURE OVER MINNESOTA WILL MOVE EAST ACROSS THE CENTRAL LAKES LATER TONIGHT. A COLD FRONT TRAILING THE LOW WILL MOVE ACROSS THE LOCAL AREA ON SUNDAY MORNING. THE FRONT WILL STALL OVER CENTRAL OHIO SUNDAY EVENING AND THEN MOVE LITTLE THROUGH MIDWEEK AS WAVES OF LOW PRESSURE MOVE ALONG THE FRONT. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... A LAKE BREEZE STRETCHING FROM LAKE TO CRAWFORD (PA) COUNTIES HAS KEPT TEMPS NOTABLY COOLER THAN INLAND. THE GRADIENT WIND WILL INCREASE THIS EVENING AND BY 00Z THE WINDS SHOULD BE OUT OF THE SOUTH/SOUTHEAST FOR ALL AREAS. THIS WILL HAVE THE EFFECT OF WARMING TEMPERATURES IN ERIE PA OVERNIGHT...RESULTING IN WARMER OVERNIGHT TEMPERATURES THAN TODAY`S MAX. WARM AIR ADVECTION...CLOUDS...AND STRONG WINDS WILL PREVENT MUCH COOLING ELSEWHERE WITH MOST AREAS STAYING IN THE 40S AND LOWER 50S. THE NEW GUIDANCE IS SHOWING A BROKEN LINE OF SHOWERS DEVELOPING AHEAD OF THE FRONT AS IT MOVES INTO NW OH AFTER 06Z. IT LOOKS LIKE THIS LINE WILL REACH ABOUT THE I-77 CORRIDOR BY DAYBREAK. HAVE TRIMMED AND ADJUSTED POPS TO ACCOUNT FOR THIS SCENARIO. THE NEW GUIDANCE INCLUDING THE LATEST HRRR ARE NOW SIMILAR SO CONFIDENCE IS HIGH TODAY. MOST LOCATIONS WILL SEE AN HOUR OR TWO OF LIGHT PRECIP WITH QPF TOTALS LESS THAN A TENTH OF AN INCH. UNTIL THE PRECIP ARRIVES...THE THICKENING CLOUDS SHOULD KEEP TEMPS FROM DROPPING TOO MUCH. WINDS WILL INCREASE MOST IN ANY PRECIPITATION WITH THE FROPA DURING THE EARLY MORNING HOURS WITH GUSTS AROUND 30 MPH. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/... IT WILL BE AN ACTIVE PERIOD FOR WEATHER. THE COLD FRONT SHOULD PUSH SE OF THE AREA ON SUNDAY AND THEN STALL JUST TO THE SOUTH. THIS FEATURE WILL EVENTUALLY COME BACK NORTH AS A WARM FRONT. THE BIG QUESTION IS WHEN THAT WILL HAPPEN. MOST OF THE GUIDANCE SHOWS A WAVE INTERACTING WITH THE FRONT ON MONDAY. THIS WILL FORCE THE FRONT NORTH TO NEAR LAKE ERIE. EXPECT INSTABILITY TO BUILD AS THIS HAPPENS. WILL NEED TO STICK WITH HIGH POPS FOR MONDAY WITH A MENTION OF THUNDER AS WELL. UNSETTLED WEATHER WILL CONTINUE MONDAY NIGHT INTO TUESDAY NIGHT AS WELL AS THE FRONT LINGERS. THE INSTABILITY REALLY BUILDS ON TUESDAY WITH SOME SURFACE BASED CAPE AND LI`S DIPPING BELOW ZERO. FOR NOW WILL LIMIT THUNDER CHANCES TO THE DAYLIGHT HOURS BUT THAT MAY NEED TO BE EXPANDED DEPENDING ON WHAT THE FRONT DOES. THE PERIOD SHOULD BE WARM WITH HIGHS IN THE 60S EXPECT NEAR THE IMMEDIATE LAKE SHORE. OVERALL...THE CHANGES TO THE FORECAST ARE PRETTY MINIMAL FROM THE PREVIOUS PACKAGE. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... BEGINNING AT 12Z WEDNESDAY THE GFS AND ECMWF MODELS BEGIN TO DIVERGE WITH THE GFS SHOWING A CLOSED SURFACE LOW OVER KANSAS, WHILE THE ECMWF RESOLVES AN INVERTED THERMAL TROUGH OVER THE EASTERN CENTRAL PLAINS. THE GFS TRACKS THE LOW INTO WESTERN INDIANA BY THURSDAY MORNING SPREADING RAIN SHOWERS OVER THE AREA. RAIN ALSO BEGINS TO FALL WITH THE ECMWF SOLUTION AROUND THIS TIME ALONG A STATIONARY BOUNDARY. IT APPEARS THE ECMWF IS STRUGGLING TO RESOLVE THE SYSTEM, PERHAPS DUE TO A BROAD MID-LEVEL RIDGE DEVELOPING OVER THE NE QUADRANT. NONETHELESS A BAROCLINIC ZONE WILL DEVELOP AS THE SYSTEM MATURES THROUGH THE WEEKEND. THE TEMPERATURE FORECAST WILL BE A CHALLENGE AND WILL DEPEND ON THE TRACK AND DEVELOPMENT OF THE LOW. THE ECMWF SOLUTION WILL YIELD LOWER DAYTIME TEMPS AS A BOUNDARY SETS UP ACROSS CENTRAL OHIO. THE GFS HAS A MUCH BETTER DEFINED WARM SECTOR ADVECTING WARMER AIR INTO THE REGION. FOR NOW GOING WITH A BLEND OF THE 2 SOLUTIONS. WILL CONTINUE TO ADJUST FORECAST AS MODELS HOPEFULLY CONVERGE ON A SIMILAR SOLUTION. AT THE LATEST BOTH MODELS SHOW THE SYSTEM PASSING THROUGH THE AREA BY SATURDAY AFTERNOON WITH THE ECMWF HINTING AT A BRIEF SHOT OF COOLER AIR ON THE BACKSIDE OF THE SYSTEM. A FLURRY MAY BE POSSIBLE ACROSS THE HIGHER TERRAIN THAT EVENING. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... VFR WITH MID AND HIGH CLOUDS TONIGHT AND AN INCREASING SOUTH WIND AHEAD OF A COLD FRONT. THE LOW LEVEL JET WILL INCREASE AND WILL INCLUDE LOW LEVEL WIND SHEAR TONIGHT. THERE COULD BE A FEW SHOWERS WITH THE FRONTAL PASSAGE ABOUT 10Z KTOL TO 15Z KERI BUT CONDITIONS WILL LIKELY REMAIN VFR WITH A SLIGHT WIND SHIFT. PATCHES OF STRATOCUMULUS (BKN050) SHOULD CLEAR OUT ON SUNDAY AS DRIER AIR SPREADS IN FROM THE WEST. WSW WINDS WILL REMAIN RATHER GUSTY UNTIL SUNDAY EVENING. .OUTLOOK...NON VFR DEVELOPING MONDAY AND LASTING INTO WED MORNING. && .MARINE... A COLD FRONT WILL SWEEP ACROSS THE LAKE TOWARD MORNING WITH FAIRLY STRONG SOUTHERLY FLOW AHEAD OF THE FEATURE. EXPECTED STRONG DOWN SLOPE WINDS OVER NORTHWEST PA TO DEVELOP OVER THE LAKE SHORE FROM THE CITY OF ERIE TO RIPLEY NEW YORK OF ABOUT 30 KNOTS AFTER MIDNIGHT. WINDS WILL INCREASE TO 15 TO 25 KNOTS ELSEWHERE OVER THE LAKE. WITH COLD WATER IN PLACE A SOMEWHAT STABLE BOUNDARY LAYER WILL INHIBIT SOME MIXING OF HIGHER WINDS OFF THE SURFACE. WILL ISSUE A SMALL CRAFT ADVISORY FOR THIS EVENING UNTIL THE MIDDLE OF SUNDAY AFTERNOON. THE GRADIENT WILL RELAX SUNDAY AFTERNOON AND EVENING AS WEAK HIGH PRESSURE BRIEFLY BUILDS OVER THE LAKE. THE FRONTAL BOUNDARY WILL LIFT NORTH BACK ACROSS THE LAKE MONDAY NIGHT AND REMAIN NEAR THE LAKE THROUGH MUCH OF THE WEEK WITH WIND SHIFTS AT TIMES AS IT MEANDERS NEARBY. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 4 PM EDT SUNDAY FOR LEZ142>149. && $$ SYNOPSIS...KUBINA NEAR TERM...JAMISON/KUBINA SHORT TERM...KUBINA LONG TERM...MAYERS AVIATION...KOSARIK MARINE...LAPLANTE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
311 PM CDT FRI APR 5 2013 .SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT) ISSUED AT 311 PM CDT FRI APR 5 2013 WATER VAPOR IMAGERY THIS AFTERNOON SHOWING A MID-LEVEL SHORTWAVE TROUGH MOVING THROUGH THE INTERMOUNTAIN WEST. AT THE SURFACE... CYCLOGENESIS WAS TAKING PLACE EAST OF THE WY ROCKIES WITH A WARM FRONT EXTENDING THROUGH NEBRASKA. LIFT AHEAD OF THE LOW AND OVER THE WARM FRONT WAS PRODUCING INCREASING MID-LEVEL CLOUD WITH RADAR MOSAIC/SURFACE OBSERVATIONS INDICATING SPORADIC -SN REACHING THE GROUND FROM WEST CENTRAL-SOUTH CENTRAL MN. OTHERWISE...HIGH/MID CLOUDS WERE INCREASING/THICKENING FROM WEST TO EAST ACROSS THE FORECAST AREA WITH TEMPERATURES RANGING FROM THE UPPER 30S ACROSS NORTH CENTRAL WI TO 50 ACROSS PORTIONS OF NORTHEAST IA/FAR SOUTHWEST WI. FOR TONIGHT...SURFACE LOW WILL CONTINUE TO DEVELOP AND MOVE OUT OF THE PLAINS INTO SOUTHERN MN BY 12Z WITH INCREASING 850-700MB MOISTURE TRANSPORT/ISENTROPIC LIFT AHEAD OF THE LOW FOCUSING INTO AREAS NORTHEAST OF I-94. AS A RESULT...CONFIDENT ENOUGH TO CARRY LIKELY TO CATEGORICAL POPS ACROSS THAT AREA...TAPERING OFF TO CHANCES SOUTHWEST OF I-94. AS FAR AS PRECIPITATION TYPES...RAP SOUNDINGS NORTHEAST OF I-94 SHOW EVAPORATIVE COOLING AS THE COLUMN SATURATES...WITH BOUNDARY LAYER STILL WARM ENOUGH TO SUPPORT RAIN. THE NAM ON THE OTHERHAND COOLS THE ENTIRE COLUMN BELOW 0C FOR ALL SNOW WHICH SEEMS A BIT AGGRESSIVE. BOTTOM LINE...LOOKS LIKE A RAIN/SNOW MIX MOVING IN MAINLY ALONG AND NORTH OF I-94 THIS EVENING. LOOKS LIKE MAIN SNOW AREA WILL BE NORTH OF THE AREA...BUT TAYLOR COUNTY COULD BE COLD ENOUGH TO SEE ACCUMULATIONS OF 1/2 TO PERHAPS AS MUCH AS 2 INCHES ACROSS FAR NORTHERN PORTION OF THE COUNTY. AS WARMER AIR ALOFT MOVES INTO THE AREA AFTER MIDNIGHT...LOOK FOR THE SNOW TO BECOME MORE OF A RAIN/SLEET MIX...POSSIBLY ALL RAIN TOWARD MORNING. MODELS CONTINUE TO SHOW THE LOW MOVING EAST THROUGH CENTRAL WI ON SATURDAY WITH AREAS ALONG AND SOUTH OF I-90 IN THE WARM SECTOR. RAIN EXPECTED TO CONTINUE ALONG AND NORTH OF THE LOW. MEANWHILE...THE NAM DEVELOPS SOME 0-3KM MUCAPE LATE MORNING/AFTERNOON IN THE WARM SECTOR OF AROUND 400J/KG. THIS WILL BE AHEAD OF FAIRLY STRONG 925-700MB FRONTOGENESIS ASSOCIATED WITH THE COLD FRONT OF THE LOW. BUFKIT SHOWING THAT THIS IS LONG/SKINNY CAPE WHICH WILL LIKELY SUSTAIN A FEW THUNDERSTORMS. BASED ON THIS SIGNAL...WILL CONTINUE THE THREAT FOR A FEW STORMS IN THE FORECAST MAINLY ALONG/SOUTH OF I-90. OTHERWISE...LOOK FOR TEMPERATURES TO CLIMB INTO THE 55-60 DEGREE RANGE SOUTH OF THE WARM FRONT...AND IN THE 40S TO NEAR 50 ALONG AND NORTH OF I-94. RAIN AND WARMTH FOR SNOWMELT MAY LEAD TO SOME HYDRO ISSUES. DETAILS OF THIS IS COVERED IN THE HYDROLOGY SECTION BELOW. THE LOW PULLS EAST INTO THE GREAT LAKES REGION SATURDAY NIGHT WITH LINGERING RAIN CHANCES CONFINED TO THE EVENING HOURS ALONG AND EAST OF THE MISSISSIPPI RIVER. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 311 PM CDT FRI APR 5 2013 SUNDAY EXPECTED TO BE DRY AS A RIDGE OF HIGH PRESSURE DRIFTS ACROSS THE REGION. LOOK FOR IN THE MIDDLE 40S TO MIDDLE 50S. FOR SUNDAY NIGHT INTO MONDAY...A DEEPENING UPPER LEVEL TROUGH OF LOW PRESSURE OVER THE WESTERN STATES WILL PRODUCE INCREASING SOUTHWEST FLOW ALOFT INTO THE UPPER MISSISSIPPI RIVER VALLEY REGION. CYCLOGENESIS AND BROAD MOISTURE TRANSPORT ACROSS THE PLAINS INTO OUR AREA WILL PRODUCE A CHANCE OF A RAIN OR RAIN/SNOW MIX SUNDAY NIGHT AND ALL RAIN ON MONDAY. PLAN ON LOWS SUNDAY NIGHT IN THE 30S TO NEAR 40 WITH HIGHS ON MONDAY IN THE UPPER 40S TO THE MIDDLE 50S. MEDIUM RANGE MODELS SHOWING A RATHER ACTIVE WEATHER PATTERN FOR THE REST OF THE WORK WEEK. HOWEVER...THEY OFFER DIFFERING SOLUTIONS WITH REGARD TO THE EVOLUTION OF THE WESTERN TROUGH AND SURFACE CYCLOGENESIS AND IMPACT ON THE UPPER MISSISSIPPI RIVER VALLEY REGION. THE GFS AND GEM SHOWING SOME SIMILARITY IN EJECTING THE TROUGH/SURFACE LOW TOWARD THE AREA MONDAY NIGHT THROUGH TUESDAY NIGHT WITH MORE PHASING WITH THE NORTHERN STREAM FLOW. THIS KEEPS US IN AN OVERALL WARMER/RAIN SCENARIO. THE ECMWF ON THE OTHER HAND WANTS TO KEEP THE FLOW SPLIT THROUGH TUESDAY WHICH KEEPS THE LOW OVER THE PLAINS THUS KEEPING AREAS MAINLY NORTH OF I-90 DRY WITH UPSTREAM RIDGING. THE ECMWF THEN TAKES THE MAIN SURFACE LOW TRACK FARTHER SOUTH INTO THE OHIO RIVER VALLEY REGION WITH AN INVERTED TROUGH OVER US. THIS MAY LEAD TO A COLDER RAIN OR RAIN SNOW MIX. WILL GO WITH A MODEL CONSENSUS FOR NOW AND HOPE FOR BETTER RESOLUTION WITH LATER RUNS. CONSENSUS YIELDS A CHANCE OF RAIN FROM MONDAY NIGHT STRAIGHT THROUGH FRIDAY. TEMPERATURES THROUGH THE PERIOD LOOK TO BE COLDER THAN NORMAL WITH GENERAL TROUGHINESS AND PRECIPITATION. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY) ISSUED 1225 PM CDT FRI APR 5 2013 HIGH PRESSURE WAS RE-TREATING EASTWARD AS AN AREA OF LOW PRESSURE WAS DEVELOPING OVER THE PLAINS. SWATH OF WARM ADVECTION/FRONTOGENESIS PUSHING INTO SOUTH CENTRAL MINNESOTA. 05.15Z HRRR TAKES THIS BAND OF FRONTOGENESIS ACROSS THE AREA LATE THIS AFTERNOON THROUGH EARLY EVENING. QUESTION WILL BE HOW MUCH LOW LEVEL SATURATION THERE IS FOR LOWER CLOUDS AND SHOWERS. MODELS SUGGEST VFR CEILINGS AND HAVE TAILORED THE TAFS WITH VFR CEILINGS WITH SOME SHOWERS. FOCUS THEN LOOKS TO BE NORTH OF THE TAF SITES THROUGH LATE EVENING AND OVERNIGHT....WITH THE NEXT BATCH OF PRECIPITATION AFFECTING THE TAF SITES AFTER 12Z SATURDAY AS THE CEILINGS LOWER INTO THE MVFR CATEGORY. && .HYDROLOGY... ISSUED AT 311 PM CDT FRI APR 5 2013 RIVER STATUS... ICE JAM ISSUES NOW BEING REPORTED ON THE BLACK ON THE NORTH SIDE OF NEILLSVILLE WITH THAWING. HYDROGRAPHS ACROSS THE REST OF AREA SHOW TRIBUTARY RIVERS AND STREAMS INTO THE MISSISSIPPI RUNNING WITHIN BANK BUT HIGHER THAN NORMAL GIVEN THE SNOW MELT. MOST OF THE HIGHER RIVER FLOWS ARE CONFINED TO RIVERS NORTH OF I-90 WHERE SNOW PACK STILL EXISTS. BESIDES THE BLACK RIVER...THE TREMPEALEAU IS ALSO A CONCERN AT THE MOMENT. SNOW PACK... LATEST NOHRSC DATA SHOWED SNOW WATER EQUIVALENTS STILL IN THE 1-3 INCH RANGE OVER WINONA...BUFFALO...TREMPEALEAU AND JACKSON COUNTIES...WHILE 2-4 INCH AMOUNTS WERE PRESENT IN CLARK AND TAYLOR COUNTIES. RAINFALL... THE SYSTEM COMING IN FOR TONIGHT AND SATURDAY IS EXPECTED TO PRODUCE 1/4 OF AN INCH OR LESS SOUTHWEST OF I-94 AND AROUND 1/2 INCH RAINFALL/LIQUID EQUIVALENT FROM ANY SNOW NORTH OF HIGHWAY 10 IN WISCONSIN. ADDITIONAL RAINFALL IS POSSIBLE SUNDAY NIGHT WITH THE POTENTIAL FOR MORE MODERATE RAINFALL MONDAY THROUGH WEDNESDAY OF NEXT WEEK. TEMPERATURES... TEMPERATURES IN THE MIDDLE 30S TO MIDDLE/UPPER 40S TODAY CONTINUES TO PRODUCE SNOWMELT. TEMPERATURES MAY NOT FALL BELOW FREEZING TONIGHT ALONG WITH WARMER CONDITIONS ANTICIPATED ON SATURDAY. THIS WILL CAUSE ADDITIONAL SNOW MELT. MOST OF THE NEXT 7 DAYS LOOK TO HAVE DAYTIME TEMPERATURES AT LEAST 40 FOR CONTINUED FAVORABLE SNOW MELT CONDITIONS. FROST DEPTH... FROST DEPTHS ACROSS THE AREA REMAIN DEEP...AVERAGING AROUND 1 FOOT TO 1 1/2 FEET SOUTH OF I-90...AND UP TO 3 FEET ACROSS PORTIONS OF NORTH CENTRAL WISCONSIN. THIS WILL LIKELY CAUSE ADDITIONAL RUNOFF OF SNOW MELT AND FALLEN PRECIPITATION INTO STREAMS AND RIVERS. SUMMARY... DUE TO LESS RAINFALL EXPECTED FOR TONIGHT THROUGH SATURDAY...MAIN FLOODING CONCERN WOULD COME MOSTLY FROM SNOW MELT THE NEXT FEW DAYS. RIVERS AND STREAMS FROM WINONA AND WABASHA COUNTIES INTO BUFFALO TREMPEALEAU...JACKSON...CLARK AND TAYLOR CONTINUE BE FOCUS OF CONCERN. WILL KEEP THE ESF GOING BASED ON THE LISTED FACTORS ABOVE. POTENTIAL IS THERE FOR A FLOOD WATCH...BUT WILL CONTINUE ESF AND CONTINUE ASSESSING THE SITUATION AT HAND WITH SNOWMELT AND FALLEN PRECIPITATION. WILL ALSO CONTINUE TO KEEP A VIGILANT EYE ON ON THE SITUATION FOR MODERATE RAINFALL POTENTIAL MONDAY THROUGH WEDNESDAY OF NEXT WEEK. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...RABERDING HYDROLOGY...DAS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1225 PM CDT FRI APR 5 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 341 AM CDT FRI APR 5 2013 CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED A SHORTWAVE TROUGH OVER THE PACIFIC NORTHWEST...RIDGING FROM WEST TEXAS INTO THE NORTHERN PLAINS...AND NORTHERN STREAM TROUGHING IN THE GREAT LAKES. IN THE WAKE OF THIS TROUGHING...HIGH PRESSURE HAS BEEN BUILDING IN AT THE SURFACE ACROSS MINNESOTA. 00Z MPX SOUNDING SHOWED PLENTY OF SUBSIDENCE AND DRY AIR ACCOMPANYING THE SURFACE HIGH...WITH PRECIPITABLE WATER VALUE AT 0.28 INCHES. AS A RESULT...SKIES ARE CLEAR ACROSS THE FORECAST AREA. JUST OFF TO THE WEST...MID AND HIGH LEVEL CLOUDS WERE INCREASING ACROSS THE NORTHERN PLAINS INTO WESTERN MINNESOTA...WELL DOWNSTREAM OF THE PACIFIC NORTHWEST SHORTWAVE. THESE CLOUDS ARE ASSOCIATED WITH A WARM ADVECTION REGIME ON THE TOP OF THE RIDGE...AS WELL AS HELP FROM A 120KT JET STREAK FROM SOUTHERN MANITOBA INTO EASTERN MINNESOTA. PROFILER AND VAD WIND DATA AT 850MB SHOWED A 30-50 KT SOUTH JET FROM EASTERN COLORADO INTO THE WESTERN DAKOTAS. ALSO PRESENT AT 850MB WAS A TIGHT TEMPERATURE GRADIENT...REFLECTED BY 00Z SOUNDINGS OF -6C AT BISMARCK COMPARED TO +5C AT RAPID CITY AND +10C AT NORTH PLATTE. DESPITE THE DECENT WARM ADVECTION PATTERN IN PLACE...SURFACE DEWPOINTS HAVE BEEN SLOW TO RISE. DEWPOINTS WERE ONLY IN THE LOW TO MID 30S OVER THE CENTRAL PLAINS...WHICH WAS AT LEAST HIGHER THAN IN THE DAKOTAS WHICH WERE IN THE 20S. THE FOCUS FOR THE SHORT TERM IS ON TWO PARTS... 1. WARM ADVECTION WELL DOWNSTREAM OF THE PACIFIC NORTHWEST SHORTWAVE TROUGH 2. EVENTUAL APPROACH OF THE PACIFIC NORTHWEST SHORTWAVE TROUGH SUBSIDENCE AND DRY AIR ASSOCIATED WITH THE SURFACE HIGH WILL DOMINATE THIS MORNING. AS WE HEAD INTO THE AFTERNOON...THE UPPER RIDGE AXIS OVER THE NORTHERN PLAINS IS PROGGED TO SLIDE INTO THE FORECAST AREA. THUS...AN INCREASE OF THE MID AND HIGH LEVEL CLOUDS IS LIKELY AS SEEN BACK IN THE DAKOTAS. THE QUESTIONS ARE WILL PRECIPITATION DEVELOP...AND IF SO WHERE AND WHEN...AS THE WARM ADVECTION INCREASES THROUGH THE AFTERNOON AND EVENING. THE 05.00Z GFS/REGIONAL CANADIAN ARE BY FAR THE MOST AGGRESSIVE...DEVELOPING RAIN ALONG/WEST OF THE MISSISSIPPI RIVER BETWEEN 18-00Z TODAY. THE 05.00Z NAM/05.00Z ECMWF/04.21Z SREF ALSO DEVELOP THE RAIN...BUT KEEP IT CONFINED NORTHWEST OF THE FORECAST AREA PRIOR TO 00Z. THE LACK OF MOISTURE CURRENTLY AVAILABLE WOULD SUPPORT THE DRIER SCENARIO... HOWEVER...850MB MOISTURE TRANSPORT DOES INTENSIFY THROUGH THE DAY AND BY 00Z IS POINTING ON THE WEST SIDE OF THE FORECAST AREA. THUS...FELT AT LEAST KEEPING SOME 20-50 PERCENT CHANCES LATE IN THE DAY ARE APPROPRIATE OVER THE WESTERN PORTIONS OF THE FORECAST AREA...HIGHEST FROM WABASHA INTO DODGE COUNTIES. FOR TONIGHT...MODELS PROG THE PACIFIC NORTHWEST SHORTWAVE TROUGH TO ENTER WESTERN SOUTH DAKOTA...CAUSING A SURFACE LOW TO FORM AND DEEPEN OVER SOUTHERN SOUTH DAKOTA. PERSISTENT AND INTENSIFYING WARM ADVECTION AHEAD OF THIS SHORTWAVE TROUGH AND SURFACE LOW LOOKS TO EXPAND THE AREA OF PRECIPITATION OVER MOST LOCATIONS EAST OF THE MISSISSIPPI RIVER IN THE EVENING...WHICH THEN LIFTS NORTHEAST AFTER MIDNIGHT. EVAPORATIVE COOLING MAY CAUSE THE PRECIPITATION TO SWITCH FROM RAIN TO SNOW IN THE EVENING NORTHEAST OF I-94...BUT EVENTUALLY WARMER AIR ADVECTS IN THERE AFTER MIDNIGHT ALOFT AND THEN SURFACE TO CAUSE A CHANGE-OVER TO SLEET AND RAIN. IF TEMPERATURES CAN HOLD BELOW FREEZING...A VERY BRIEF PERIOD OF FREEZING RAIN WOULD OCCUR. MODEL CONSENSUS CONTINUES TO FAVOR ALONG/NORTHEAST OF I-94 TO HAVE THE BULK OF THE PRECIPITATION...THUS PRECIPITATION CHANCES NEAR 100 SEEMS REASONABLE. REGARDING SNOWFALL ACCUMULATION...GIVEN THE GENERAL WARM SENSE TO THIS WARM ADVECTION EVENT...NOTED BY 850MB TEMPS THAT ARE ONLY -2 TO -4C WHEN IT IS SNOWING...SNOW TO WATER RATIOS SHOULD ONLY MAX OUT AROUND 10 TO 1. WITH UPWARDS OF 0.1-0.3 INCHES OF QPF PROGGED...SNOW TOTALS COULD BE AS MUCH AS 3 INCHES...THOUGH THE MAJORITY SHOULD END UP IN THE 1 TO 2 INCH RANGE...NOT ENOUGH FOR AN ADVISORY AT THIS POINT. COULD USE THE MIX PRECIPITATION AS A NEED FOR THE ADVISORY...BUT CONFIDENCE ON THE AMOUNT OF MIXED PRECIPITATION IS TOO LOW TO WARRANT ONE. TEMPERATURES TODAY WILL END UP COOLER COMPARED TO YESTERDAY DUE TO INCREASING CLOUDS AS WELL AS 850MB TEMPS BETWEEN -2 AND -6C AT 18Z. FOR TONIGHT...INCREASING SOUTHERLY WINDS PLUS CLOUDS SHOULD HELP KEEP TEMPERATURES UP AT OR ABOVE FREEZING. IN FACT...EXPECTING TEMPERATURES TO CLIMB LATE IN THE NIGHT AS THE SURFACE WARM FRONT LIFTS NORTH TOWARDS I-94. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 341 AM CDT FRI APR 5 2013 HIGHLIGHTS: 1. CURRENT PACIFIC NORTHWEST SHORTWAVE TROUGH PROGGED TO MOVE THROUGH THE AREA ON SATURDAY 2. POTENTIAL FOR AN ACTIVE BUT HARD TO TIME PRECIPITATION PATTERN SUNDAY NIGHT AND BEYOND. MODELS ARE IN REALLY GOOD AGREEMENT TRACKING THE SHORTWAVE TROUGH THAT WAS OVER SOUTH DAKOTA LATE TONIGHT INTO AND POSSIBLY THROUGH THE FORECAST AREA ON SATURDAY. STRONG DYNAMIC FORCING WITH THIS SHORTWAVE...NOTED SIMPLY BY 60-90 METER HEIGHT FALLS IN 12 HOURS AT 500MB...ALONG WITH THAT SURGE OF 850MB MOISTURE TRANSPORT AHEAD OF THE SHORTWAVE PROVIDING MOISTURE SHOULD HELP PRODUCE RAIN ACROSS MOST OF THE FORECAST AREA. THE ONLY MODEL NOT SHOWING THIS IS THE 05.00Z NAM...AT LEAST SOUTH OF I-90...WHICH SEEMS ODD GIVEN THE FORCING. THE 05.00Z REGIONAL CANADIAN IS ACTUALLY QUITE ROBUST SOUTH OF I-90 WITH QPF AMOUNTS OF 0.1-0.25 INCHES WITH A FEW ISOLATED 0.5 INCH AMOUNTS FROM VERNON INTO ADAMS COUNTIES. IT APPEARS THE HEAVIER QPF IS A RESULT OF CONVECTIVE ELEMENTS FORMING AHEAD OF THE SHORTWAVES ASSOCIATED COLD FRONT AT THE SURFACE. INSTABILITY IS FAIRLY MEAGER DUE TO CAPPING AROUND 750MB AND LIMITED MOISTURE. HOWEVER...THERE IS A ZONE OF NEGATIVE EPV DUE TO UPRIGHT INSTABILITY IN CROSS-SECTIONS AROUND 700MB...THUS A FEW THUNDERSTORMS CANNOT BE RULED OUT. PRECIPITATION SHOULD SHIFT OFF TO THE EAST PRETTY QUICK LATE IN THE AFTERNOON INTO THE EARLY EVENING FOR MOST OF THE AREA...AS STRONG SUBSIDENCE COMES IN BEHIND THE SHORTWAVE TROUGH. ONLY PLACE THIS MAY NOT OCCUR AS FAST IS NORTH AND EAST OF I-94...DUE TO THE SUGGESTION OF A SHORTWAVE COMING IN BEHIND THE SHORTWAVE TROUGH AND A MID-LEVEL FRONTOGENESIS ZONE DROPPING SOUTHEAST. TEMPERATURES MAY COOL ENOUGH TO ALLOW FOR SOME SNOW OUT OF THIS PRECIPITATION BEFORE IT ENDS BY MIDNIGHT. VERY LITTLE ACCUMULATION ANTICIPATED...THOUGH. A MAJOR PATTERN CHANGE IS FORECAST TO TAKE PLACE SUNDAY AS A POTENT SHORTWAVE TROUGH IMPACTS AND DIGS INTO THE PACIFIC NORTHWEST. HEADING INTO THE EARLY PORTION OF THE WORK WEEK...MODELS ARE IN GOOD AGREEMENT DIGGING THIS TROUGH SOUTH INTO THE FOUR CORNERS REGION... SETTING UP A SOUTHWEST FLOW PATTERN INTO THE FORECAST AREA. THIS MEANS HARD TO TIME SHORTWAVES AND THUS PLENTY OF UNCERTAINTY. TAKE FOR EXAMPLE SUNDAY NIGHT WHERE THE 05.00Z ECMWF/NAM BRING A SHORTWAVE THROUGH THE AREA WITH WIDESPREAD QPF. THE 05.00Z CANADIAN IS EVEN MORE POTENT WITH THIS SHORTWAVE AND A BIT FARTHER SOUTHEAST. ON THE OTHER HAND...THE 05.00Z GFS DOES NOT SHOW THE SHORTWAVE AT ALL...THUS RESULTING IN A DRY FORECAST. MAJORITY HERE SUGGESTS AT LEAST 30-50 PERCENT PRECIPITATION CHANCES ARE NEEDED. MOST OF THE PRECIPITATION SHOULD FALL AS RAIN...BUT COULD MIX WITH SNOW ALONG/NORTHEAST OF I-94. THE MOST INTERESTING TIME PERIOD OF NEXT WEEK IS TUESDAY INTO WEDNESDAY...AS THE UPPER TROUGH IN THE SOUTHWEST U.S. EJECTS OUT. THERE REMAINS A WHOLE LOT OF UNCERTAINTY ON THE TIMING AND DETAILS OF THIS EJECTION. HOWEVER...EVERY MODEL AVAILABLE AT THIS POINT HAS SOME SYSTEM AFFECTING THE AREA. WE COULD END UP SEEING CONVECTION IN THE GFS SCENARIO...POTENTIAL FOR MODERATE TO HEAVY RAINFALL IN ANY MODEL...AND EVEN SOME SNOW ON THE BACK SIDE OF THE SYSTEM ONCE THE UPPER TROUGH MOVES OVERHEAD. WE WILL HAVE TO KEEP A WATCH ON THIS PERIOD. GIVEN THE CONSENSUS AGREEMENT FOR PRECIPITATION TUESDAY INTO TUESDAY NIGHT...RAISED PRECIPITATION CHANCES DURING THIS PERIOD. MAY NEED TO RAISE CHANCES FOR WEDNESDAY AS WELL. && .AVIATION...THROUGH 18Z SATURDAY 1225 PM CDT FRI APR 5 2013 HIGH PRESSURE WAS RE-TREATING EASTWARD AS AN AREA OF LOW PRESSURE WAS DEVELOPING OVER THE PLAINS. SWATH OF WARM ADVECTION/FRONTOGENESIS PUSHING INTO SOUTH CENTRAL MINNESOTA. 05.15Z HRRR TAKES THIS BAND OF FRONTOGENESIS ACROSS THE AREA LATE THIS AFTERNOON THROUGH EARLY EVENING. QUESTION WILL BE HOW MUCH LOW LEVEL SATURATION THERE IS FOR LOWER CLOUDS AND SHOWERS. MODELS SUGGEST VFR CEILINGS AND HAVE TAILORED THE TAFS WITH VFR CEILINGS WITH SOME SHOWERS. FOCUS THEN LOOKS TO BE NORTH OF THE TAF SITES THROUGH LATE EVENING AND OVERNIGHT....WITH THE NEXT BATCH OF PRECIPITATION AFFECTING THE TAF SITES AFTER 12Z SATURDAY AS THE CEILINGS LOWER INTO THE MVFR CATEGORY. && .HYDROLOGY... ISSUED AT 341 AM CDT FRI APR 5 2013 RIVER STATUS... HYDROGRAPHS ACROSS THE AREA SHOW TRIBUTARY RIVERS AND STREAMS INTO THE MISSISSIPPI RUNNING WITHIN BANK FLOWS WITH A FEW HIGHER THAN NORMAL GIVEN THE SNOW MELT. MOST OF THE HIGH RIVER FLOWS ARE CONFINED TO RIVERS NORTH OF I-90 WHERE SNOW PACK STILL EXISTS. THE WHITEWATER...TREMPEALEAU AND BLACK RIVERS ARE OF CONCERN AT THE MOMENT. SNOW PACK... LATEST NOHRSC DATA SHOWED SNOW WATER EQUIVALENTS STILL IN THE 1-2 INCH RANGE OVER WINONA...BUFFALO...TREMPEALEAU AND JACKSON COUNTIES...WHILE 2-3 INCH AMOUNTS WERE PRESENT IN CLARK AND TAYLOR COUNTIES. RAINFALL... THE SYSTEM COMING IN FOR TONIGHT AND SATURDAY NOW LOOKS TO NOT PRODUCE AS MUCH RAINFALL AS PREVIOUSLY EXPECTED...MOSTLY LESS THAN 1/3 OF AN INCH SOUTHWEST OF I-94 TO 1/3 TO 1/2 INCH NORTH OF I-94. NOTE THAT SOME SNOW IS FORECAST TONIGHT NORTH AND EAST OF I-94...WHICH COULD TOTAL UP TO 0.3 OF LIQUID EQUIVALENT. ADDITIONAL RAINFALL IS POSSIBLE SUNDAY NIGHT WITH POTENTIAL FOR MODERATE TO HEAVY RAINFALL TUESDAY INTO WEDNESDAY OF NEXT WEEK. TEMPERATURES... A COOLER DAY BUT STILL PLENTY WARM ENOUGH FOR SNOW MELT IS EXPECTED TODAY AS HIGHS CLIMB INTO THE 40S. PROBLEM TONIGHT IS THAT TEMPERATURES MAY NOT FALL BELOW FREEZING AND WITH WARMER CONDITIONS ANTICIPATED ON SATURDAY...WE COULD REALLY SEE SOME SNOW MELT. MOST OF THE NEXT 7 DAYS LOOK TO HAVE DAYTIME TEMPERATURES AT LEAST 40...THUS FAVORABLE CONDITIONS ARE IN PLACE FOR SNOW MELT EVERY DAY. FROST DEPTH... FROST REMAINS FAIRLY DEEP IN THE GROUND STILL. AS OF 7 AM APRIL 4TH...CUBA CITY WI WAS AT 16 INCHES...WHITEHALL WAS AT 19 INCHES...AND BLOOMER IN CHIPPEWA COUNTY WAS AT 38 INCHES. SUMMARY... NOW THAT LESS RAINFALL IS FORECAST THAN EXPECTED FOR TONIGHT AND SATURDAY...ANY FLOODING CONCERN WOULD COME MOSTLY FROM SNOW MELT THE NEXT FEW DAYS. CERTAINLY ANY RIVERS AND STREAMS FROM WINONA AND WABASHA COUNTIES INTO BUFFALO TREMPEALEAU...JACKSON...CLARK AND TAYLOR WOULD BE OF CONCERN. HAVE DECIDED TO KEEP THE ESF GOING AND EXPANDED IT INTO WINONA COUNTY GIVEN THE ISSUES BEING EXPERIENCED ON THE WHITEWATER RIVER. CONSIDERED ISSUING A FLOOD WATCH FOR JUST RIVERS...BUT GIVEN THAT LESS RAINFALL IS EXPECTED AND WE ALREADY HAVE EXPERIENCED RIVERS IN AND OUT OF MINOR FLOOD STAGE THE LAST FEW DAYS...FEEL THE ESF IS STILL VALID. MAY STILL NEED A FLOOD WATCH...THOUGH...AS CERTAINTY INCREASES ABOUT THE AMOUNT OF SNOW MELT THIS WEEKEND. EITHER WAY...DEFINITELY NEED TO KEEP AN EYE ON TUESDAY INTO WEDNESDAY OF NEXT WEEK. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...RABERDING HYDROLOGY...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
657 AM CDT FRI APR 5 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 341 AM CDT FRI APR 5 2013 CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED A SHORTWAVE TROUGH OVER THE PACIFIC NORTHWEST...RIDGING FROM WEST TEXAS INTO THE NORTHERN PLAINS...AND NORTHERN STREAM TROUGHING IN THE GREAT LAKES. IN THE WAKE OF THIS TROUGHING...HIGH PRESSURE HAS BEEN BUILDING IN AT THE SURFACE ACROSS MINNESOTA. 00Z MPX SOUNDING SHOWED PLENTY OF SUBSIDENCE AND DRY AIR ACCOMPANYING THE SURFACE HIGH...WITH PRECIPITABLE WATER VALUE AT 0.28 INCHES. AS A RESULT...SKIES ARE CLEAR ACROSS THE FORECAST AREA. JUST OFF TO THE WEST...MID AND HIGH LEVEL CLOUDS WERE INCREASING ACROSS THE NORTHERN PLAINS INTO WESTERN MINNESOTA...WELL DOWNSTREAM OF THE PACIFIC NORTHWEST SHORTWAVE. THESE CLOUDS ARE ASSOCIATED WITH A WARM ADVECTION REGIME ON THE TOP OF THE RIDGE...AS WELL AS HELP FROM A 120KT JET STREAK FROM SOUTHERN MANITOBA INTO EASTERN MINNESOTA. PROFILER AND VAD WIND DATA AT 850MB SHOWED A 30-50 KT SOUTH JET FROM EASTERN COLORADO INTO THE WESTERN DAKOTAS. ALSO PRESENT AT 850MB WAS A TIGHT TEMPERATURE GRADIENT...REFLECTED BY 00Z SOUNDINGS OF -6C AT BISMARCK COMPARED TO +5C AT RAPID CITY AND +10C AT NORTH PLATTE. DESPITE THE DECENT WARM ADVECTION PATTERN IN PLACE...SURFACE DEWPOINTS HAVE BEEN SLOW TO RISE. DEWPOINTS WERE ONLY IN THE LOW TO MID 30S OVER THE CENTRAL PLAINS...WHICH WAS AT LEAST HIGHER THAN IN THE DAKOTAS WHICH WERE IN THE 20S. THE FOCUS FOR THE SHORT TERM IS ON TWO PARTS... 1. WARM ADVECTION WELL DOWNSTREAM OF THE PACIFIC NORTHWEST SHORTWAVE TROUGH 2. EVENTUAL APPROACH OF THE PACIFIC NORTHWEST SHORTWAVE TROUGH SUBSIDENCE AND DRY AIR ASSOCIATED WITH THE SURFACE HIGH WILL DOMINATE THIS MORNING. AS WE HEAD INTO THE AFTERNOON...THE UPPER RIDGE AXIS OVER THE NORTHERN PLAINS IS PROGGED TO SLIDE INTO THE FORECAST AREA. THUS...AN INCREASE OF THE MID AND HIGH LEVEL CLOUDS IS LIKELY AS SEEN BACK IN THE DAKOTAS. THE QUESTIONS ARE WILL PRECIPITATION DEVELOP...AND IF SO WHERE AND WHEN...AS THE WARM ADVECTION INCREASES THROUGH THE AFTERNOON AND EVENING. THE 05.00Z GFS/REGIONAL CANADIAN ARE BY FAR THE MOST AGGRESSIVE...DEVELOPING RAIN ALONG/WEST OF THE MISSISSIPPI RIVER BETWEEN 18-00Z TODAY. THE 05.00Z NAM/05.00Z ECMWF/04.21Z SREF ALSO DEVELOP THE RAIN...BUT KEEP IT CONFINED NORTHWEST OF THE FORECAST AREA PRIOR TO 00Z. THE LACK OF MOISTURE CURRENTLY AVAILABLE WOULD SUPPORT THE DRIER SCENARIO... HOWEVER...850MB MOISTURE TRANSPORT DOES INTENSIFY THROUGH THE DAY AND BY 00Z IS POINTING ON THE WEST SIDE OF THE FORECAST AREA. THUS...FELT AT LEAST KEEPING SOME 20-50 PERCENT CHANCES LATE IN THE DAY ARE APPROPRIATE OVER THE WESTERN PORTIONS OF THE FORECAST AREA...HIGHEST FROM WABASHA INTO DODGE COUNTIES. FOR TONIGHT...MODELS PROG THE PACIFIC NORTHWEST SHORTWAVE TROUGH TO ENTER WESTERN SOUTH DAKOTA...CAUSING A SURFACE LOW TO FORM AND DEEPEN OVER SOUTHERN SOUTH DAKOTA. PERSISTENT AND INTENSIFYING WARM ADVECTION AHEAD OF THIS SHORTWAVE TROUGH AND SURFACE LOW LOOKS TO EXPAND THE AREA OF PRECIPITATION OVER MOST LOCATIONS EAST OF THE MISSISSIPPI RIVER IN THE EVENING...WHICH THEN LIFTS NORTHEAST AFTER MIDNIGHT. EVAPORATIVE COOLING MAY CAUSE THE PRECIPITATION TO SWITCH FROM RAIN TO SNOW IN THE EVENING NORTHEAST OF I-94...BUT EVENTUALLY WARMER AIR ADVECTS IN THERE AFTER MIDNIGHT ALOFT AND THEN SURFACE TO CAUSE A CHANGE-OVER TO SLEET AND RAIN. IF TEMPERATURES CAN HOLD BELOW FREEZING...A VERY BRIEF PERIOD OF FREEZING RAIN WOULD OCCUR. MODEL CONSENSUS CONTINUES TO FAVOR ALONG/NORTHEAST OF I-94 TO HAVE THE BULK OF THE PRECIPITATION...THUS PRECIPITATION CHANCES NEAR 100 SEEMS REASONABLE. REGARDING SNOWFALL ACCUMULATION...GIVEN THE GENERAL WARM SENSE TO THIS WARM ADVECTION EVENT...NOTED BY 850MB TEMPS THAT ARE ONLY -2 TO -4C WHEN IT IS SNOWING...SNOW TO WATER RATIOS SHOULD ONLY MAX OUT AROUND 10 TO 1. WITH UPWARDS OF 0.1-0.3 INCHES OF QPF PROGGED...SNOW TOTALS COULD BE AS MUCH AS 3 INCHES...THOUGH THE MAJORITY SHOULD END UP IN THE 1 TO 2 INCH RANGE...NOT ENOUGH FOR AN ADVISORY AT THIS POINT. COULD USE THE MIX PRECIPITATION AS A NEED FOR THE ADVISORY...BUT CONFIDENCE ON THE AMOUNT OF MIXED PRECIPITATION IS TOO LOW TO WARRANT ONE. TEMPERATURES TODAY WILL END UP COOLER COMPARED TO YESTERDAY DUE TO INCREASING CLOUDS AS WELL AS 850MB TEMPS BETWEEN -2 AND -6C AT 18Z. FOR TONIGHT...INCREASING SOUTHERLY WINDS PLUS CLOUDS SHOULD HELP KEEP TEMPERATURES UP AT OR ABOVE FREEZING. IN FACT...EXPECTING TEMPERATURES TO CLIMB LATE IN THE NIGHT AS THE SURFACE WARM FRONT LIFTS NORTH TOWARDS I-94. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 341 AM CDT FRI APR 5 2013 HIGHLIGHTS: 1. CURRENT PACIFIC NORTHWEST SHORTWAVE TROUGH PROGGED TO MOVE THROUGH THE AREA ON SATURDAY 2. POTENTIAL FOR AN ACTIVE BUT HARD TO TIME PRECIPITATION PATTERN SUNDAY NIGHT AND BEYOND. MODELS ARE IN REALLY GOOD AGREEMENT TRACKING THE SHORTWAVE TROUGH THAT WAS OVER SOUTH DAKOTA LATE TONIGHT INTO AND POSSIBLY THROUGH THE FORECAST AREA ON SATURDAY. STRONG DYNAMIC FORCING WITH THIS SHORTWAVE...NOTED SIMPLY BY 60-90 METER HEIGHT FALLS IN 12 HOURS AT 500MB...ALONG WITH THAT SURGE OF 850MB MOISTURE TRANSPORT AHEAD OF THE SHORTWAVE PROVIDING MOISTURE SHOULD HELP PRODUCE RAIN ACROSS MOST OF THE FORECAST AREA. THE ONLY MODEL NOT SHOWING THIS IS THE 05.00Z NAM...AT LEAST SOUTH OF I-90...WHICH SEEMS ODD GIVEN THE FORCING. THE 05.00Z REGIONAL CANADIAN IS ACTUALLY QUITE ROBUST SOUTH OF I-90 WITH QPF AMOUNTS OF 0.1-0.25 INCHES WITH A FEW ISOLATED 0.5 INCH AMOUNTS FROM VERNON INTO ADAMS COUNTIES. IT APPEARS THE HEAVIER QPF IS A RESULT OF CONVECTIVE ELEMENTS FORMING AHEAD OF THE SHORTWAVES ASSOCIATED COLD FRONT AT THE SURFACE. INSTABILITY IS FAIRLY MEAGER DUE TO CAPPING AROUND 750MB AND LIMITED MOISTURE. HOWEVER...THERE IS A ZONE OF NEGATIVE EPV DUE TO UPRIGHT INSTABILITY IN CROSS-SECTIONS AROUND 700MB...THUS A FEW THUNDERSTORMS CANNOT BE RULED OUT. PRECIPITATION SHOULD SHIFT OFF TO THE EAST PRETTY QUICK LATE IN THE AFTERNOON INTO THE EARLY EVENING FOR MOST OF THE AREA...AS STRONG SUBSIDENCE COMES IN BEHIND THE SHORTWAVE TROUGH. ONLY PLACE THIS MAY NOT OCCUR AS FAST IS NORTH AND EAST OF I-94...DUE TO THE SUGGESTION OF A SHORTWAVE COMING IN BEHIND THE SHORTWAVE TROUGH AND A MID-LEVEL FRONTOGENESIS ZONE DROPPING SOUTHEAST. TEMPERATURES MAY COOL ENOUGH TO ALLOW FOR SOME SNOW OUT OF THIS PRECIPITATION BEFORE IT ENDS BY MIDNIGHT. VERY LITTLE ACCUMULATION ANTICIPATED...THOUGH. A MAJOR PATTERN CHANGE IS FORECAST TO TAKE PLACE SUNDAY AS A POTENT SHORTWAVE TROUGH IMPACTS AND DIGS INTO THE PACIFIC NORTHWEST. HEADING INTO THE EARLY PORTION OF THE WORK WEEK...MODELS ARE IN GOOD AGREEMENT DIGGING THIS TROUGH SOUTH INTO THE FOUR CORNERS REGION... SETTING UP A SOUTHWEST FLOW PATTERN INTO THE FORECAST AREA. THIS MEANS HARD TO TIME SHORTWAVES AND THUS PLENTY OF UNCERTAINTY. TAKE FOR EXAMPLE SUNDAY NIGHT WHERE THE 05.00Z ECMWF/NAM BRING A SHORTWAVE THROUGH THE AREA WITH WIDESPREAD QPF. THE 05.00Z CANADIAN IS EVEN MORE POTENT WITH THIS SHORTWAVE AND A BIT FARTHER SOUTHEAST. ON THE OTHER HAND...THE 05.00Z GFS DOES NOT SHOW THE SHORTWAVE AT ALL...THUS RESULTING IN A DRY FORECAST. MAJORITY HERE SUGGESTS AT LEAST 30-50 PERCENT PRECIPITATION CHANCES ARE NEEDED. MOST OF THE PRECIPITATION SHOULD FALL AS RAIN...BUT COULD MIX WITH SNOW ALONG/NORTHEAST OF I-94. THE MOST INTERESTING TIME PERIOD OF NEXT WEEK IS TUESDAY INTO WEDNESDAY...AS THE UPPER TROUGH IN THE SOUTHWEST U.S. EJECTS OUT. THERE REMAINS A WHOLE LOT OF UNCERTAINTY ON THE TIMING AND DETAILS OF THIS EJECTION. HOWEVER...EVERY MODEL AVAILABLE AT THIS POINT HAS SOME SYSTEM AFFECTING THE AREA. WE COULD END UP SEEING CONVECTION IN THE GFS SCENARIO...POTENTIAL FOR MODERATE TO HEAVY RAINFALL IN ANY MODEL...AND EVEN SOME SNOW ON THE BACK SIDE OF THE SYSTEM ONCE THE UPPER TROUGH MOVES OVERHEAD. WE WILL HAVE TO KEEP A WATCH ON THIS PERIOD. GIVEN THE CONSENSUS AGREEMENT FOR PRECIPITATION TUESDAY INTO TUESDAY NIGHT...RAISED PRECIPITATION CHANCES DURING THIS PERIOD. MAY NEED TO RAISE CHANCES FOR WEDNESDAY AS WELL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 652 AM CDT FRI APR 5 2013 CLOUDS WILL MOVE INTO THE AREA LATE THIS MORNING AND AFTERNOON AHEAD OF A LOW PRESSURE SYSTEM MOVING OUT OF THE NORTHERN PLAINS. CEILINGS WILL QUICKLY DROP FROM 10K FEET TO AROUND 3500 FEET. THESE CEILINGS WILL REMAIN BETWEEN 2500 AND 3500 FEET FOR THE REMAINDER OF THE PERIOD. SHOWERS WILL MOVE INTO KRST AROUND 05.19Z AND KLSE 05.22Z. DUE TO MODEL INCONSISTENCY...THERE ARE SOME QUESTIONS ON WHETHER THERE WILL BE SOME DRY PERIODS TONIGHT. SINCE THIS WAS STILL A BIT UNCLEAR...JUST KEPT THE THREAT OF SHOWERS GOING FOR THE REMAINDER OF THE FORECAST. && .HYDROLOGY... ISSUED AT 341 AM CDT FRI APR 5 2013 RIVER STATUS... HYDROGRAPHS ACROSS THE AREA SHOW TRIBUTARY RIVERS AND STREAMS INTO THE MISSISSIPPI RUNNING WITHIN BANK FLOWS WITH A FEW HIGHER THAN NORMAL GIVEN THE SNOW MELT. MOST OF THE HIGH RIVER FLOWS ARE CONFINED TO RIVERS NORTH OF I-90 WHERE SNOW PACK STILL EXISTS. THE WHITEWATER...TREMPEALEAU AND BLACK RIVERS ARE OF CONCERN AT THE MOMENT. SNOW PACK... LATEST NOHRSC DATA SHOWED SNOW WATER EQUIVALENTS STILL IN THE 1-2 INCH RANGE OVER WINONA...BUFFALO...TREMPEALEAU AND JACKSON COUNTIES...WHILE 2-3 INCH AMOUNTS WERE PRESENT IN CLARK AND TAYLOR COUNTIES. RAINFALL... THE SYSTEM COMING IN FOR TONIGHT AND SATURDAY NOW LOOKS TO NOT PRODUCE AS MUCH RAINFALL AS PREVIOUSLY EXPECTED...MOSTLY LESS THAN 1/3 OF AN INCH SOUTHWEST OF I-94 TO 1/3 TO 1/2 INCH NORTH OF I-94. NOTE THAT SOME SNOW IS FORECAST TONIGHT NORTH AND EAST OF I-94...WHICH COULD TOTAL UP TO 0.3 OF LIQUID EQUIVALENT. ADDITIONAL RAINFALL IS POSSIBLE SUNDAY NIGHT WITH POTENTIAL FOR MODERATE TO HEAVY RAINFALL TUESDAY INTO WEDNESDAY OF NEXT WEEK. TEMPERATURES... A COOLER DAY BUT STILL PLENTY WARM ENOUGH FOR SNOW MELT IS EXPECTED TODAY AS HIGHS CLIMB INTO THE 40S. PROBLEM TONIGHT IS THAT TEMPERATURES MAY NOT FALL BELOW FREEZING AND WITH WARMER CONDITIONS ANTICIPATED ON SATURDAY...WE COULD REALLY SEE SOME SNOW MELT. MOST OF THE NEXT 7 DAYS LOOK TO HAVE DAYTIME TEMPERATURES AT LEAST 40...THUS FAVORABLE CONDITIONS ARE IN PLACE FOR SNOW MELT EVERY DAY. FROST DEPTH... FROST REMAINS FAIRLY DEEP IN THE GROUND STILL. AS OF 7 AM APRIL 4TH...CUBA CITY WI WAS AT 16 INCHES...WHITEHALL WAS AT 19 INCHES...AND BLOOMER IN CHIPPEWA COUNTY WAS AT 38 INCHES. SUMMARY... NOW THAT LESS RAINFALL IS FORECAST THAN EXPECTED FOR TONIGHT AND SATURDAY...ANY FLOODING CONCERN WOULD COME MOSTLY FROM SNOW MELT THE NEXT FEW DAYS. CERTAINLY ANY RIVERS AND STREAMS FROM WINONA AND WABASHA COUNTIES INTO BUFFALO TREMPEALEAU...JACKSON...CLARK AND TAYLOR WOULD BE OF CONCERN. HAVE DECIDED TO KEEP THE ESF GOING AND EXPANDED IT INTO WINONA COUNTY GIVEN THE ISSUES BEING EXPERIENCED ON THE WHITEWATER RIVER. CONSIDERED ISSUING A FLOOD WATCH FOR JUST RIVERS...BUT GIVEN THAT LESS RAINFALL IS EXPECTED AND WE ALREADY HAVE EXPERIENCED RIVERS IN AND OUT OF MINOR FLOOD STAGE THE LAST FEW DAYS...FEEL THE ESF IS STILL VALID. MAY STILL NEED A FLOOD WATCH...THOUGH...AS CERTAINTY INCREASES ABOUT THE AMOUNT OF SNOW MELT THIS WEEKEND. EITHER WAY...DEFINITELY NEED TO KEEP AN EYE ON TUESDAY INTO WEDNESDAY OF NEXT WEEK. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...BOYNE HYDROLOGY...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
341 AM CDT FRI APR 5 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 341 AM CDT FRI APR 5 2013 CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED A SHORTWAVE TROUGH OVER THE PACIFIC NORTHWEST...RIDGING FROM WEST TEXAS INTO THE NORTHERN PLAINS...AND NORTHERN STREAM TROUGHING IN THE GREAT LAKES. IN THE WAKE OF THIS TROUGHING...HIGH PRESSURE HAS BEEN BUILDING IN AT THE SURFACE ACROSS MINNESOTA. 00Z MPX SOUNDING SHOWED PLENTY OF SUBSIDENCE AND DRY AIR ACCOMPANYING THE SURFACE HIGH...WITH PRECIPITABLE WATER VALUE AT 0.28 INCHES. AS A RESULT...SKIES ARE CLEAR ACROSS THE FORECAST AREA. JUST OFF TO THE WEST...MID AND HIGH LEVEL CLOUDS WERE INCREASING ACROSS THE NORTHERN PLAINS INTO WESTERN MINNESOTA...WELL DOWNSTREAM OF THE PACIFIC NORTHWEST SHORTWAVE. THESE CLOUDS ARE ASSOCIATED WITH A WARM ADVECTION REGIME ON THE TOP OF THE RIDGE...AS WELL AS HELP FROM A 120KT JET STREAK FROM SOUTHERN MANITOBA INTO EASTERN MINNESOTA. PROFILER AND VAD WIND DATA AT 850MB SHOWED A 30-50 KT SOUTH JET FROM EASTERN COLORADO INTO THE WESTERN DAKOTAS. ALSO PRESENT AT 850MB WAS A TIGHT TEMPERATURE GRADIENT...REFLECTED BY 00Z SOUNDINGS OF -6C AT BISMARCK COMPARED TO +5C AT RAPID CITY AND +10C AT NORTH PLATTE. DESPITE THE DECENT WARM ADVECTION PATTERN IN PLACE...SURFACE DEWPOINTS HAVE BEEN SLOW TO RISE. DEWPOINTS WERE ONLY IN THE LOW TO MID 30S OVER THE CENTRAL PLAINS...WHICH WAS AT LEAST HIGHER THAN IN THE DAKOTAS WHICH WERE IN THE 20S. THE FOCUS FOR THE SHORT TERM IS ON TWO PARTS... 1. WARM ADVECTION WELL DOWNSTREAM OF THE PACIFIC NORTHWEST SHORTWAVE TROUGH 2. EVENTUAL APPROACH OF THE PACIFIC NORTHWEST SHORTWAVE TROUGH SUBSIDENCE AND DRY AIR ASSOCIATED WITH THE SURFACE HIGH WILL DOMINATE THIS MORNING. AS WE HEAD INTO THE AFTERNOON...THE UPPER RIDGE AXIS OVER THE NORTHERN PLAINS IS PROGGED TO SLIDE INTO THE FORECAST AREA. THUS...AN INCREASE OF THE MID AND HIGH LEVEL CLOUDS IS LIKELY AS SEEN BACK IN THE DAKOTAS. THE QUESTIONS ARE WILL PRECIPITATION DEVELOP...AND IF SO WHERE AND WHEN...AS THE WARM ADVECTION INCREASES THROUGH THE AFTERNOON AND EVENING. THE 05.00Z GFS/REGIONAL CANADIAN ARE BY FAR THE MOST AGGRESSIVE...DEVELOPING RAIN ALONG/WEST OF THE MISSISSIPPI RIVER BETWEEN 18-00Z TODAY. THE 05.00Z NAM/05.00Z ECMWF/04.21Z SREF ALSO DEVELOP THE RAIN...BUT KEEP IT CONFINED NORTHWEST OF THE FORECAST AREA PRIOR TO 00Z. THE LACK OF MOISTURE CURRENTLY AVAILABLE WOULD SUPPORT THE DRIER SCENARIO... HOWEVER...850MB MOISTURE TRANSPORT DOES INTENSIFY THROUGH THE DAY AND BY 00Z IS POINTING ON THE WEST SIDE OF THE FORECAST AREA. THUS...FELT AT LEAST KEEPING SOME 20-50 PERCENT CHANCES LATE IN THE DAY ARE APPROPRIATE OVER THE WESTERN PORTIONS OF THE FORECAST AREA...HIGHEST FROM WABASHA INTO DODGE COUNTIES. FOR TONIGHT...MODELS PROG THE PACIFIC NORTHWEST SHORTWAVE TROUGH TO ENTER WESTERN SOUTH DAKOTA...CAUSING A SURFACE LOW TO FORM AND DEEPEN OVER SOUTHERN SOUTH DAKOTA. PERSISTENT AND INTENSIFYING WARM ADVECTION AHEAD OF THIS SHORTWAVE TROUGH AND SURFACE LOW LOOKS TO EXPAND THE AREA OF PRECIPITATION OVER MOST LOCATIONS EAST OF THE MISSISSIPPI RIVER IN THE EVENING...WHICH THEN LIFTS NORTHEAST AFTER MIDNIGHT. EVAPORATIVE COOLING MAY CAUSE THE PRECIPITATION TO SWITCH FROM RAIN TO SNOW IN THE EVENING NORTHEAST OF I-94...BUT EVENTUALLY WARMER AIR ADVECTS IN THERE AFTER MIDNIGHT ALOFT AND THEN SURFACE TO CAUSE A CHANGE-OVER TO SLEET AND RAIN. IF TEMPERATURES CAN HOLD BELOW FREEZING...A VERY BRIEF PERIOD OF FREEZING RAIN WOULD OCCUR. MODEL CONSENSUS CONTINUES TO FAVOR ALONG/NORTHEAST OF I-94 TO HAVE THE BULK OF THE PRECIPITATION...THUS PRECIPITATION CHANCES NEAR 100 SEEMS REASONABLE. REGARDING SNOWFALL ACCUMULATION...GIVEN THE GENERAL WARM SENSE TO THIS WARM ADVECTION EVENT...NOTED BY 850MB TEMPS THAT ARE ONLY -2 TO -4C WHEN IT IS SNOWING...SNOW TO WATER RATIOS SHOULD ONLY MAX OUT AROUND 10 TO 1. WITH UPWARDS OF 0.1-0.3 INCHES OF QPF PROGGED...SNOW TOTALS COULD BE AS MUCH AS 3 INCHES...THOUGH THE MAJORITY SHOULD END UP IN THE 1 TO 2 INCH RANGE...NOT ENOUGH FOR AN ADVISORY AT THIS POINT. COULD USE THE MIX PRECIPITATION AS A NEED FOR THE ADVISORY...BUT CONFIDENCE ON THE AMOUNT OF MIXED PRECIPITATION IS TOO LOW TO WARRANT ONE. TEMPERATURES TODAY WILL END UP COOLER COMPARED TO YESTERDAY DUE TO INCREASING CLOUDS AS WELL AS 850MB TEMPS BETWEEN -2 AND -6C AT 18Z. FOR TONIGHT...INCREASING SOUTHERLY WINDS PLUS CLOUDS SHOULD HELP KEEP TEMPERATURES UP AT OR ABOVE FREEZING. IN FACT...EXPECTING TEMPERATURES TO CLIMB LATE IN THE NIGHT AS THE SURFACE WARM FRONT LIFTS NORTH TOWARDS I-94. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 341 AM CDT FRI APR 5 2013 HIGHLIGHTS: 1. CURRENT PACIFIC NORTHWEST SHORTWAVE TROUGH PROGGED TO MOVE THROUGH THE AREA ON SATURDAY 2. POTENTIAL FOR AN ACTIVE BUT HARD TO TIME PRECIPITATION PATTERN SUNDAY NIGHT AND BEYOND. MODELS ARE IN REALLY GOOD AGREEMENT TRACKING THE SHORTWAVE TROUGH THAT WAS OVER SOUTH DAKOTA LATE TONIGHT INTO AND POSSIBLY THROUGH THE FORECAST AREA ON SATURDAY. STRONG DYNAMIC FORCING WITH THIS SHORTWAVE...NOTED SIMPLY BY 60-90 METER HEIGHT FALLS IN 12 HOURS AT 500MB...ALONG WITH THAT SURGE OF 850MB MOISTURE TRANSPORT AHEAD OF THE SHORTWAVE PROVIDING MOISTURE SHOULD HELP PRODUCE RAIN ACROSS MOST OF THE FORECAST AREA. THE ONLY MODEL NOT SHOWING THIS IS THE 05.00Z NAM...AT LEAST SOUTH OF I-90...WHICH SEEMS ODD GIVEN THE FORCING. THE 05.00Z REGIONAL CANADIAN IS ACTUALLY QUITE ROBUST SOUTH OF I-90 WITH QPF AMOUNTS OF 0.1-0.25 INCHES WITH A FEW ISOLATED 0.5 INCH AMOUNTS FROM VERNON INTO ADAMS COUNTIES. IT APPEARS THE HEAVIER QPF IS A RESULT OF CONVECTIVE ELEMENTS FORMING AHEAD OF THE SHORTWAVES ASSOCIATED COLD FRONT AT THE SURFACE. INSTABILITY IS FAIRLY MEAGER DUE TO CAPPING AROUND 750MB AND LIMITED MOISTURE. HOWEVER...THERE IS A ZONE OF NEGATIVE EPV DUE TO UPRIGHT INSTABILITY IN CROSS-SECTIONS AROUND 700MB...THUS A FEW THUNDERSTORMS CANNOT BE RULED OUT. PRECIPITATION SHOULD SHIFT OFF TO THE EAST PRETTY QUICK LATE IN THE AFTERNOON INTO THE EARLY EVENING FOR MOST OF THE AREA...AS STRONG SUBSIDENCE COMES IN BEHIND THE SHORTWAVE TROUGH. ONLY PLACE THIS MAY NOT OCCUR AS FAST IS NORTH AND EAST OF I-94...DUE TO THE SUGGESTION OF A SHORTWAVE COMING IN BEHIND THE SHORTWAVE TROUGH AND A MID-LEVEL FRONTOGENESIS ZONE DROPPING SOUTHEAST. TEMPERATURES MAY COOL ENOUGH TO ALLOW FOR SOME SNOW OUT OF THIS PRECIPITATION BEFORE IT ENDS BY MIDNIGHT. VERY LITTLE ACCUMULATION ANTICIPATED...THOUGH. A MAJOR PATTERN CHANGE IS FORECAST TO TAKE PLACE SUNDAY AS A POTENT SHORTWAVE TROUGH IMPACTS AND DIGS INTO THE PACIFIC NORTHWEST. HEADING INTO THE EARLY PORTION OF THE WORK WEEK...MODELS ARE IN GOOD AGREEMENT DIGGING THIS TROUGH SOUTH INTO THE FOUR CORNERS REGION... SETTING UP A SOUTHWEST FLOW PATTERN INTO THE FORECAST AREA. THIS MEANS HARD TO TIME SHORTWAVES AND THUS PLENTY OF UNCERTAINTY. TAKE FOR EXAMPLE SUNDAY NIGHT WHERE THE 05.00Z ECMWF/NAM BRING A SHORTWAVE THROUGH THE AREA WITH WIDESPREAD QPF. THE 05.00Z CANADIAN IS EVEN MORE POTENT WITH THIS SHORTWAVE AND A BIT FARTHER SOUTHEAST. ON THE OTHER HAND...THE 05.00Z GFS DOES NOT SHOW THE SHORTWAVE AT ALL...THUS RESULTING IN A DRY FORECAST. MAJORITY HERE SUGGESTS AT LEAST 30-50 PERCENT PRECIPITATION CHANCES ARE NEEDED. MOST OF THE PRECIPITATION SHOULD FALL AS RAIN...BUT COULD MIX WITH SNOW ALONG/NORTHEAST OF I-94. THE MOST INTERESTING TIME PERIOD OF NEXT WEEK IS TUESDAY INTO WEDNESDAY...AS THE UPPER TROUGH IN THE SOUTHWEST U.S. EJECTS OUT. THERE REMAINS A WHOLE LOT OF UNCERTAINTY ON THE TIMING AND DETAILS OF THIS EJECTION. HOWEVER...EVERY MODEL AVAILABLE AT THIS POINT HAS SOME SYSTEM AFFECTING THE AREA. WE COULD END UP SEEING CONVECTION IN THE GFS SCENARIO...POTENTIAL FOR MODERATE TO HEAVY RAINFALL IN ANY MODEL...AND EVEN SOME SNOW ON THE BACK SIDE OF THE SYSTEM ONCE THE UPPER TROUGH MOVES OVERHEAD. WE WILL HAVE TO KEEP A WATCH ON THIS PERIOD. GIVEN THE CONSENSUS AGREEMENT FOR PRECIPITATION TUESDAY INTO TUESDAY NIGHT...RAISED PRECIPITATION CHANCES DURING THIS PERIOD. MAY NEED TO RAISE CHANCES FOR WEDNESDAY AS WELL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1100 PM CDT THU APR 4 2013 HIGH PRESSURE WILL SETTLE ACROSS THE UPPER MISSISSIPPI RIVER VALLEY OVERNIGHT...WITH VFR SKC CONDITIONS AND GENERALLY LIGHT/VRB WINDS. HIGH/MID LEVEL CLOUDS WILL BE ON THE INCREASE FRIDAY AFTERNOON...AHEAD OF AN APPROACHING NORTHERN PLAINS SHORTWAVE TROUGH. WINDS WILL INCREASE AND BECOME SOUTHERLY BEHIND THE DEPARTING HIGH. VFR WILL CONTINUE. FRIDAY NIGHT/SAT POSES SOME DIFFICULTIES FOR CIGS AND RAIN POTENTIAL. OVERALL...THE NAM/GFS/EC FAVOR KEEPING THE DEEPER SATURATION AND PCPN CHANCES JUST NORTH OF KRST/KLSE. HOWEVER...SOME SIGNS THAT THE MOISTURE COULD BE A BIT FARTHER SOUTH...BRINGING A THREAT FOR MVFR CIGS. ALSO...A GOOD SLUG OF 925-850 MB WARM AIR ADVECTION/MOISTURE TRANSPORT...WHICH COULD RESULT IN SOME PCPN CHANCES. THINK THE BEST CHANCES WILL COME WITH THE SYSTEM/S COLD FRONT...WHICH MOVES EAST ACROSS THE REGION LATE SAT MORNING/AFTERNOON. THAT SAID...ENOUGH FORCING FRI EVENING TO ADD -SHRA TO THE TAFS. && .HYDROLOGY... ISSUED AT 341 AM CDT FRI APR 5 2013 RIVER STATUS... HYDROGRAPHS ACROSS THE AREA SHOW TRIBUTARY RIVERS AND STREAMS INTO THE MISSISSIPPI RUNNING WITHIN BANK FLOWS WITH A FEW HIGHER THAN NORMAL GIVEN THE SNOW MELT. MOST OF THE HIGH RIVER FLOWS ARE CONFINED TO RIVERS NORTH OF I-90 WHERE SNOW PACK STILL EXISTS. THE WHITEWATER...TREMPEALEAU AND BLACK RIVERS ARE OF CONCERN AT THE MOMENT. SNOW PACK... LATEST NOHRSC DATA SHOWED SNOW WATER EQUIVALENTS STILL IN THE 1-2 INCH RANGE OVER WINONA...BUFFALO...TREMPEALEAU AND JACKSON COUNTIES...WHILE 2-3 INCH AMOUNTS WERE PRESENT IN CLARK AND TAYLOR COUNTIES. RAINFALL... THE SYSTEM COMING IN FOR TONIGHT AND SATURDAY NOW LOOKS TO NOT PRODUCE AS MUCH RAINFALL AS PREVIOUSLY EXPECTED...MOSTLY LESS THAN 1/3 OF AN INCH SOUTHWEST OF I-94 TO 1/3 TO 1/2 INCH NORTH OF I-94. NOTE THAT SOME SNOW IS FORECAST TONIGHT NORTH AND EAST OF I-94...WHICH COULD TOTAL UP TO 0.3 OF LIQUID EQUIVALENT. ADDITIONAL RAINFALL IS POSSIBLE SUNDAY NIGHT WITH POTENTIAL FOR MODERATE TO HEAVY RAINFALL TUESDAY INTO WEDNESDAY OF NEXT WEEK. TEMPERATURES... A COOLER DAY BUT STILL PLENTY WARM ENOUGH FOR SNOW MELT IS EXPECTED TODAY AS HIGHS CLIMB INTO THE 40S. PROBLEM TONIGHT IS THAT TEMPERATURES MAY NOT FALL BELOW FREEZING AND WITH WARMER CONDITIONS ANTICIPATED ON SATURDAY...WE COULD REALLY SEE SOME SNOW MELT. MOST OF THE NEXT 7 DAYS LOOK TO HAVE DAYTIME TEMPERATURES AT LEAST 40...THUS FAVORABLE CONDITIONS ARE IN PLACE FOR SNOW MELT EVERY DAY. FROST DEPTH... FROST REMAINS FAIRLY DEEP IN THE GROUND STILL. AS OF 7 AM APRIL 4TH...CUBA CITY WI WAS AT 16 INCHES...WHITEHALL WAS AT 19 INCHES...AND BLOOMER IN CHIPPEWA COUNTY WAS AT 38 INCHES. SUMMARY... NOW THAT LESS RAINFALL IS FORECAST THAN EXPECTED FOR TONIGHT AND SATURDAY...ANY FLOODING CONCERN WOULD COME MOSTLY FROM SNOW MELT THE NEXT FEW DAYS. CERTAINLY ANY RIVERS AND STREAMS FROM WINONA AND WABASHA COUNTIES INTO BUFFALO TREMPEALEAU...JACKSON...CLARK AND TAYLOR WOULD BE OF CONCERN. HAVE DECIDED TO KEEP THE ESF GOING AND EXPANDED IT INTO WINONA COUNTY GIVEN THE ISSUES BEING EXPERIENCED ON THE WHITEWATER RIVER. CONSIDERED ISSUING A FLOOD WATCH FOR JUST RIVERS...BUT GIVEN THAT LESS RAINFALL IS EXPECTED AND WE ALREADY HAVE EXPERIENCED RIVERS IN AND OUT OF MINOR FLOOD STAGE THE LAST FEW DAYS...FEEL THE ESF IS STILL VALID. MAY STILL NEED A FLOOD WATCH...THOUGH...AS CERTAINTY INCREASES ABOUT THE AMOUNT OF SNOW MELT THIS WEEKEND. EITHER WAY...DEFINITELY NEED TO KEEP AN EYE ON TUESDAY INTO WEDNESDAY OF NEXT WEEK. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION.....RIECK HYDROLOGY...AJ
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1059 PM MDT SAT APR 6 2013 .UPDATE... ISSUED AT 1059 PM MDT SAT APR 6 2013 CURRENT WATER VAPOR IMAGERY INDICATING SHORT WAVE EMBEDDED WITHIN THE MODERATE WESTERLY FLOW ALOFT TRANLATING ACROSS EASTERN COLORADO WITH DISTINCT CLEARING BEHIND SAID WAVE. REGIONAL RADARS INDICATING ISOLATED TO SCATTERED ECHOES MOVING ACROSS THE EASTERN PLAINS AS WELL...THOUGH WEB CAMS AND OBSERVATIONS INDICATING MAINLY VIRGA WITH ONLY A FEW SPRINKLES MAKING IT TO THE GROUND WITH DRY SUB CLOUD LAYER AND DEW PT DEPRESSIONS STILL 15-20F. UPDATE ISSUED AT 558 PM MDT SAT APR 6 2013 ADDED ISOLATED POPS TO SOUTHERN PORTIONS OF THE I-25 CORRIDOR WITH CURRENT RADAR TRENDS INDICATING ECHOES ACROSS THE AREA...THOUGH NOT SURE HOW MUCH IF ANY IS MAKING IT TO THE GROUND WITH DEW PT DEPRESSIONS IN EXCESS OF 20 DEGREE. WILL CONTINUE TO MONITOR RADAR TRENDS THROUGH THE EVENING WITH EMBEDDED SHORT WAVE ACROSS WESTERN COLORADO TRANSLATING ACROSS THE STATE AND LATEST HRRR DATA SPREADING A FEW SHOWERS ACROSS THE PIKES PEAK AND PALMER DVD AROUND MIDNIGHT. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 323 PM MDT SAT APR 6 2013 CURRENTLY...UPPER 60S TO NR 70 FOR THE PLAINS...AND 40S-50S FOR THE MT AREAS. WINDS GENERALLY ARE WELL BEHAVED...BUT WILL SEE A FEW ISOLD WIND GUSTS INT EH 30KT RANGE DUE TO VIRGA. UPSTREAM SHORTWAVE TO OUR N IS EASILY SEEN IN IR IMAGERY ACROSS NRN UT AND ID. THIS WILL CROSS OUR AREA FROM AROUND 03Z-09Z TONIGHT...SO EXPECT THIS TO COINCIDE WITH HIGHEST POPS OVR THE MTS. BEST CHANCE FOR SHOWERS WILL BE OVER THE CONTDVD N OF KMYP...WHERE THE HIGHER ELEVATIONS COULD PICK UP ONE TO THREE INCHES OF SNOW THROUGH TOMORROW FROM SCT SHSN. TOMORROW...WILL START OFF FAIRLY QUIET...THEN COULD SEE A FEW SHOWERS DEVELOP ACROSS THE AREA AFTER ABOUT 21Z...IN RESPONSE TO INCREASING UPPER LIFT FROM THE APPROACHING STORM SYSTEM NOW OVER THE N PACIFIC. INCREASING LAPSE RATES WILL LEAD TO LIFTED INDICES IN THE MINUS TWO RANGE IN THE AFTERNOON...WHICH COULD LEAD TO A FEW LTG STRIKES ACROSS THE AREA. BELIEVE LTG WILL BE RATHER LIMITED...BUT WILL LEAVE MENTION IN THE FORECAST FOR NOW TO PRESERVE CONTINUITY AND COORDINATION WITH SURROUNDING WFOS. TEMPS SHOULD BE FAIRLY CLOSE TO TODAY`S READINGS...MAYBE A COUPLE DEGREES HIGHER AS WRLY FLOW INCREASES. FIRE WX DANGER ALSO IS ON THE INCREASE TOMORROW DUE TO THE INCREASE IN WINDS AND CONTINUED DRY CONDITIONS OVERALL. BEST BET FOR CRITICAL FIRE WX WILL BE OVER THE SAN LUIS VALLEY...WHICH SHOULD SEE GUSTS IN THE 25-35 KT RANGE IN THE AFTERNOON AND EARLY EVE. WILL HOIST THE RED FLAG FOR THE VALLEY FOR THIS PERIOD. ALSO COULD SEE SOME CRITICAL FIRE WX CONDITIONS ACROSS THE LOWER ARKANSAS FROM FREMONT INTO NRN PUEBLO COUNTY...AND IN HUERFANO COUNTY DUE TO GAP FLOW THROUGH LA VETA PASS. AT THIS TIME...LOOKS TOO LIMITED IN SCOPE TO INCLUDE IN THE RED FLAG...BUT MAY HAVE TO BE ADDED BY LATER SHIFTS IF IT APPEARS THAT WINDS WILL BE MORE WIDESPREAD. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 323 PM MDT SAT APR 6 2013 ...POSSIBLE WEATHER TRIFECTA ACROSS SOUTHERN COLORADO MONDAY... MONDAY HAS A LOT OF WEATHER HAZARD POTENTIAL...INCLUDING POSSIBLE SEVERE WEATHER ON THE FAR EASTERN PLAINS...FIRE WEATHER OVER MOST OF THE REST OF THE PLAINS AND WINTER WEATHER IN THE MOUNTAINS. FIRST THE FIRE WEATHER. MONDAY AFTERNOON INTO EARLY EVENING DEFINITELY LOOKS LIKE A HIGH FIRE DANGER PERIOD ACROSS MUCH OF THE SOUTHEAST PLAINS...WITH WINDS...HUMIDITIES AND FUELS ALL MEETING CRITERIA. WITH GUSTS TO 40 MPH...HUMIDITIES BELOW 15 PERCENT AND DRY FUELS... THIS IS DAY WHEN OUTDOOR BURNING SHOULD BE SUSPENDED AND ANY OTHER ACTIVITIES THAT MIGHT SPARK A FIRE SHOULD BE AVOIDED. NOW THE SEVERE POTENTIAL. PARAMETERS ON BOTH MAJOR MODELS USED FOR THIS TIME FRAME ARE INDICATING POSSIBLE SEVERE CONVECTION ACROSS THE FAR EASTERN PLAINS MONDAY AFTERNOON AND EVENING. PARAMETERS INDICATE TORNADO AS WELL AS LARGE HAIL POTENTIAL. THE THREAT AREA CURRENTLY LOOKS EAST OF NORTH-SOUTH LINE THROUGH LA JUNTA. THUNDERSTORMS POSSIBLE ELSEWHERE THIS DAY AS WELL BUT LIKELY NOT SEVERE. NOW THE SNOW. IT WILL SPREAD INTO THE HIGH COUNTRY MONDAY AFTERNOON AND START TO SPREAD ONTO THE ADJACENT PLAINS BY TUESDAY MORNING. STILL BIG UNCERTAINTIES REGARDING THE STORM TRACK. CONTINUES TO LOOK PRETTY CERTAIN FOR GOOD SNOW AND WIND POTENTIAL OVER THE MOUNTAINS AND ALONG THE PALMER DIVIDE...WITH MORE IFFY POTENTIAL ELSEWHERE. REGARDLESS OF THE MODEL...STILL LOOKS LIKE A PERIOD OF AT LEAST SOME SNOW AND WIND FOR MOST OF SOUTHERN COLORADO...INCLUDING THE HIGH MOUNTAIN VALLEYS AND THE SOUTHEAST PLAINS FROM LATE MONDAY NIGHT INTO TUESDAY EVENING. AS WE GET CLOSER...WINTER WEATHER HIGHLIGHTS WILL LIKELY BE NEEDED FOR THE MOUNTAINS AND PALMER DIVIDE AND POSSIBLY ELSEWHERE. STORM SHOULD BE MOSTLY EAST OF THE AREA BY WEDNESDAY EXCEPT FOR LINGERING WIND...COLD AND MOUNTAIN SNOW SHOWERS. STAY TUNED. LW && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY EVENING) ISSUED AT 1059 PM MDT SAT APR 6 2013 SHORT WAVE EMBEDDED WITHIN THE MODERATE WESTERLY FLOW ALOFT TRANLATING ACROSS EASTERN COLORADO WITH DISTINCT CLEARING BEHIND SAID WAVE AT THIS TIME. WAVE PRODUCING MAINLY VIRGA WITH CIGS RANGING BETWEEN 070-100 ACROSS THE PLAINS AT THIS TIME. WILL SEE CLEARING FROM WEST TO EAST THROUGH THE REST OF THE EVENING WITH VFR CONDITIONS CONTINUING FOR KCOS...KPUB AND KALS FOR THE NEXT 24 HOURS. COULD SEE ISOLD -TSRA DEVELOPING ACROSS THE HIGHER TERRAIN TOMORROW AFTENROON...WHICH COULD RESULT IN SOME LOCALIZED STRONG WIND GUSTS. && .PUB WATCHES/WARNINGS/ADVISORIES... FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING FOR COZ228>233-235-237. RED FLAG WARNING FROM 1 PM TO 9 PM MDT SUNDAY FOR COZ224. && $$ UPDATE...MW SHORT TERM...ROSE LONG TERM...LW AVIATION...MW
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
410 AM EDT SUN APR 7 2013 ...MODERATE RISK FOR RIP CURRENTS TODAY... .SYNOPSIS... HIGH PRESSURE WILL PERSIST THROUGH MID WEEK. A COLD FRONT WILL APPROACH THE AREA LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THROUGH SUNRISE...LOW CLOUDS HAVE YET TO DEVELOP ACROSS THE AREA EARLY THIS MORNING. KCLX VWP SHOWS WINDS ALOFT HAVE VEERED MORE SOUTHERLY AS EXPECTED WHILE AT THE SURFACE WINDS REMAIN LIGHT NORTHEAST. IT APPEARS ANY ISENTROPIC ASSENT THAT IS OCCURRING IS JUST NOT STRONG ENOUGH TO PRODUCE MUCH CLOUD COVER YET AND INCOMING RAP GUIDANCE CONTINUES TO SUGGEST THIS WILL BE THE CASE THROUGH SUNRISE. HAVE ADJUSTED SKY COVER DOWN TO MOSTLY CLEAR TO PARTLY CLOUDY AND REMOVED ALL INDICATIONS OF MOSTLY CLOUDY SKIES. HOWEVER...A BRIEF PERIOD OF MOSTLY CLOUDY CONDITIONS CAN NOT BE RULED OUT MAINLY ACROSS INTERIOR SOUTHEAST GEORGIA. LOWS FROM THE MID 40S WELL INLAND TO THE LOWER-MID 50S ALONG THE IMMEDIATE COAST LOOK ON TRACK. TODAY...LARGE SOUTHWEST-NORTHEAST ORIENTED HIGH PRESSURE CENTERED OFF NEW ENGLAND WILL STEADILY SHIFT FARTHER OFFSHORE TODAY AS A FAIRLY ZONAL FLOW DOMINATES ALOFT. ONGOING WEAK WARM ADVECTION WILL PUSH H8 TEMPERATURES INTO THE 8-9C RANGE WHICH WILL YIELD SLIGHTLY WARMER HIGH TEMPERATURES COMPARED TO SATURDAY. LOW-LEVEL THICKNESSES SCHEMES AND MODEL BUFR SOUNDINGS GENERALLY SUPPORT HIGHS IN THE LOWER-MID 70S WITH CONSIDERABLY COOLER TEMPERATURES IN THE LOWER 60S AT THE BEACHES WHERE OCEANIC INFLUENCES WILL BE THE GREATEST. EXPECT ANOTHER RATHER ROBUST SEA BREEZE CIRCULATION TO FORM ALONG THE BEACHES LATER TODAY WHICH WILL MOVE STEADILY INLAND DURING THE AFTERNOON HOURS. THIS WILL CAUSE TEMPERATURES TO DROP ABOUT 5-8 DEGREES ACROSS THE COASTAL COUNTIES WITH ITS PASSAGE...SIMILAR TO SATURDAY. WITH THE LACK OF STRATOCUMULUS THIS MORNING...ITS UNCLEAR EXACTLY HOW MUCH CUMULUS WILL DEVELOP LATER TODAY AS TEMPERATURES WARM INTO THE 70S. SUSPECT THERE WILL BE AT LEAST A SHALLOW...SOMEWHAT SCATTERED CUMULUS FIELD AHEAD OF THE SEA BREEZE SO WILL STICK WITH A PARTLY CLOUDY SKIES CHARACTER FOR TODAY. SKIES WILL LIKELY CLEAR A BIT IN THE WAKE OF THE SEA BREEZE AS MORE STABLE AIR IS DRAWN INLAND FROM OFF THE ATLANTIC. THIS MAY RESULT IN A PERIOD OF MOSTLY SUNNY TO SUNNY SKIES PRIOR TO SUNSET...MAINLY ACROSS THE COASTAL CORRIDORS. NO RAIN IS EXPECTED EVEN AS THE COASTAL FRONT DRAWS CLOSER TO THE COAST AND EVENTUALLY BECOMES ABSORBED IN THE BROADER SYNOPTIC FLOW. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... TONIGHT...THE AREA WILL REMAIN ALONG THE WESTERN FRINGES OF ATLANTIC HIGH PRESSURE TONIGHT. EXPECT MAINLY CLEAR SKIES TO DOMINATE WITH SOME PATCHY STRATOCUMULUS POSSIBLY MOVING INLAND FROM OFF THE ATLANTIC. THE BOUNDARY LAYER SHOULD DECOUPLE FOR MOST AREA AWAY FROM THE IMMEDIATE COAST A FEW HOURS AFTER SUNSET. GENERALLY FAVORED THE COOLER SIDE OF GUIDANCE GIVEN THE DECENT RADIATIONAL SETUP. LOWS WILL RANGE FROM THE LOWER 50S INLAND TO THE MID 50S ALONG THE IMMEDIATE COAST. A FEW UPPER 40S CAN NOT BE COMPLETELY RULED OUT...MAINLY IN THE NORMALLY COLDER LOCATIONS SUCH AS ALLENDALE AND JAMESTOWN. COULD SEE SOME SHALLOW GROUND FOG FORM AFTER MIDNIGHT...BUT ITS PROBABLY NOT WORTH MENTIONING GIVEN THE LACK OF ANY SIGNIFICANT IMPACT. MONDAY AND TUESDAY...THE FORECAST AREA WILL REMAIN ON THE PERIPHERY OF SURFACE HIGH PRESSURE IN THE ATLANTIC EARLY NEXT WEEK. THE UPPER LEVEL PATTERN WILL BECOME MORE AMPLIFIED BY TUESDAY...AS A DEEP TROUGH SHIFTS INTO THE CENTRAL PLAINS AND RIDGING STRENGTHENS ACROSS THE SOUTHEAST COAST. RISING HEIGHTS ALOFT AND SOUTH/SOUTHEAST FLOW WILL SUPPORT UNSEASONABLY WARM CONDITIONS EACH AFTERNOON. HIGH TEMPERATURES INLAND WILL RISE INTO THE UPPER 70S TO LOWER 80S ON MONDAY...WHILE WARMING SOLIDLY INTO THE LOWER 80S BY TUESDAY. THE ONSHORE COMPONENT TO THE SURFACE FLOW WILL KEEP COASTAL LOCATIONS NOTABLY COOLER...SUPPRESSING HIGH TEMPERATURES IN THE LOWER TO MID 70S NEAR THE BEACHES. ALTHOUGH LOW LEVEL MOISTURE WILL BE INCREASING...AND A SEABREEZE BOUNDARY WILL DEVELOP WITHIN MORE SUMMER-LIKE CONDITIONS...DECENT SUBSIDENCE SHOULD PREVENT DIURNAL SHOWER DEVELOPMENT. HAVE THUS CAPPED RAIN CHANCES BELOW 15 PERCENT. WEDNESDAY...DEEP LAYER RIDGING WILL GRADUALLY SHIFT FARTHER INTO THE ATLANTIC BY MID WEEK...WHILE THE ROBUST UPPER TROUGH STRETCHING FROM THE NORTHERN PLAINS TO THE SOUTHWEST STATES MAKES SOME PROGRESS EASTWARD. THIS SYSTEM WILL PROVIDE THE ENERGY TO SPAWN A SURFACE LOW AND TRAILING COLD FRONT TO THE WEST OF THE FORECAST AREA. THE GFS MODEL SOLUTIONS HAVE BEEN CONSISTENTLY MORE AGGRESSIVE IN BREAKING DOWN THE DEEP RIDGING...DECREASING SUBSIDENCE ENOUGH TO SUPPORT DIURNAL SHOWER DEVELOPMENT WEDNESDAY AFTERNOON. PREFER TO LEAN TOWARD A MORE CONSERVATIVE AND SLOWER SCENARIO...THUS CONTINUING TO KEEP RAIN CHANCES BELOW 15 PERCENT. WILL ALSO CONTINUE TO INDICATE UNSEASONABLY WARM HIGH TEMPERATURES...REACHING THE LOWER 80S AWAY FROM THE LOCALLY COOLER COASTLINE DURING THE AFTERNOON HOURS. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... MEDIUM RANGE MODEL SOLUTIONS MAINTAIN SIGNIFICANT DISCREPANCIES IN THE TIMING OF A COLD FRONT APPROACHING FROM THE WEST LATE IN THE WEEK. AN ELONGATED UPPER TROUGH OVER THE CENTRAL PLAINS WEDNESDAY NIGHT WILL BREAK INTO A MORE SPLIT FLOW FEATURE BY THURSDAY. SLOWER MODEL SOLUTIONS SUGGEST THE SOUTHERN SHORTWAVE ENERGY WILL SPIN UP A SECONDARY SURFACE LOW ALONG THE GULF COAST STATES THAT COULD DELAY THE PROGRESS OF THE FRONTAL SYSTEM. IN ADDITION...THERE IS SOME QUESTION AS TO THE RESILIENCY OF THE UPPER RIDGE AND SUBSEQUENT IMPACTS ON PRECIPITATION TIMING AND COVERAGE. UPON COLLABORATION WITH NEIGHBORING FORECAST OFFICES...PREFER TO LEAN TOWARD THE SLOWER MODELS SOLUTIONS AT THIS TIME. WILL INTRODUCE A SLIGHT CHANCE OF RAIN FROM WEST TO EAST AS EARLY AS THURSDAY...YET SUGGEST THE HIGHEST POTENTIAL FOR SHOWER/THUNDERSTORM COVERAGE FRIDAY AFTERNOON AND EVENING...WHEN THE SOUTHERN STREAM SHORTWAVE AND SURFACE LOW LIFT INTO THE AREA. REGARDLESS OF MODEL SOLUTION...THE UNSEASONABLY WARM CONDITIONS AHEAD OF THE FRONTAL SYSTEM WILL SUPPORT DECENT INSTABILITY AND SUBSEQUENT THUNDERSTORM DEVELOPMENT. THIS INSTABILITY...WHEN COMBINED WITH A POTENTIAL 40 TO 50 KT LOW LEVEL JET...COULD ALSO ALLOW THUNDERSTORMS TO BECOME STRONG AND ORGANIZED. HOWEVER...CONFIDENCE IN SUCH DETAILS THIS FAR OUT REMAINS LOW...ESPECIALLY CONSIDERING CURRENT MODEL CONSISTENCY ISSUES. EXPECT THE COLD FRONT TO HAVE CROSSED THE EAST COAST BY FRIDAY NIGHT...WITH SURFACE HIGH PRESSURE RAPIDLY REBUILDING FROM THE WEST IN ITS WAKE. HAVE MAINTAINED JUST A SLIGHT CHANCE FOR SHOWERS/THUNDERSTORMS INTO EARLY SATURDAY...WITH POPS FALLING BELOW 15 PERCENT FOR THE REMAINDER OF THE WEEKEND. HIGH TEMPERATURES WILL BE A FEW DEGREES COOLER FROM FRIDAY AFTERNOON THROUGH SUNDAY...BECOMING CLOSER TO SEASONAL NORMALS IN THE MID 70S BY THE WEEKEND. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/... GENERALLY VFR. INCREASING MOISTURE FROM OFF THE ATLANTIC WILL LIKELY SUPPORT SOME STRATOCUMULUS THROUGH SUNRISE. ITS STILL UNCLEAR AT THIS POINT HOW WIDESPREAD THESE CLOUDS WILL BECOME BUT LATEST RAP DATA SUGGESTS ANY CIGS THAT ARE ESTABLISHED WILL LIKELY REMAIN LOW-END VFR...MAINLY AT KSAV WHERE THE RISK FOR LOW CLOUDS WILL BE THE GREATEST. WILL CARRY VFR CONDITIONS AT BOTH KCHS/KSAV FOR THE NEXT 24 HOURS. WILL LIKELY SEE A PERIOD OF GUSTY WINDS IN THE WAKE OF THE AFTERNOON...POSSIBLY REACHING AS HIGH AS 15-18 KT. EXTENDED AVIATION OUTLOOK...POSSIBLE FLIGHT RESTRICTIONS IN LIGHT FOG/MIST LATE AT NIGHT AND IN THE MORNING SUNDAY NIGHT THROUGH WEDNESDAY. && .MARINE... TODAY...NORTHEAST WINDS WILL GRADUALLY TURN SOUTHEAST TODAY AS THE COASTAL TROUGH DRIFTS CLOSER TO THE COAST AND GRADUALLY BECOMES ABSORBED IN THE BROADER SYNOPTIC FLOW. WINDS WILL GENERALLY REMAIN 10-15 KT THROUGH THE DAY...ALTHOUGH THERE WILL LIKELY BE COME ENHANCEMENT NEAR THE LAND/SEA INTERFACE AND IN THE CHARLESTON HARBOR AS THE SEA BREEZE DEVELOPS AND MOVES INLAND. SEAS WILL RANGE FROM 2-4 FT NEARSHORE WATERS WITH 4-5 FT OFFSHORE WATERS. TONIGHT...THERE ARE NO CONCERNS TONIGHT WITH SOUTHEAST WINDS DOMINATING. WINDS WILL REMAIN 10-15 KT WITH SEAS 2-4 FT... HIGHEST OVER THE GEORGIA OFFSHORE WATERS MONDAY THROUGH FRIDAY...THE MARINE ZONES WILL REMAIN ALONG THE WESTERN PERIPHERY OF A LARGE AND FAIRLY STRONG RIDGE OF ATLANTIC HIGH PRESSURE THROUGH THE UPCOMING WEEK. SOUTHEAST/SOUTH CIRCULATION AROUND THE HIGH WILL BECOME ENHANCED AT TIMES BY AFTERNOON/EVENING SEA BREEZE CIRCULATIONS...BUT EXPECT WINDS TO BE CAPPED AT 10 OR 15 KT. SEAS WILL GENERALLY RANGE FROM 2 TO 4 FT THROUGH MID WEEK. THE GRADIENT WILL LIKELY TIGHTEN BETWEEN THE ATLANTIC HIGH AND AN APPROACHING COLD FRONT BY THURSDAY. WINDS AND/OR SEAS COULD THEREFORE BUILD CLOSE TO ADVISORY LEVELS LATE IN THE FORECAST PERIOD. RIP CURRENTS...OPTED TO UPGRADE TO A MODERATE RISK FOR RIP CURRENTS FOR ALL BEACHES TODAY. WW4 OUTPUT SHOWS 8 TO OCCASIONAL 9 SECOND SWELLS DOMINATING FOR MUCH OF THE DAY. TYBEE ISLAND LIFEGUARDS REPORTED RIP CURRENTS ALONG WITH SEVERAL ASSISTS AND ONE RESCUE YESTERDAY AFTERNOON. CONSIDERING SIMILAR CONDITIONS WILL BE IN PLACE TODAY...THERE IS ENOUGH EVIDENCE TO SUPPORT A MODERATE RISK...DESPITE THE FAIRLY MODEST ONSHORE WIND REGIME. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ ST/79
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
120 AM EDT SUN APR 7 2013 .SYNOPSIS... HIGH PRESSURE WILL PERSIST THROUGH THE MIDDLE OF NEXT WEEK. A COLD FRONT WILL APPROACH THE AREA LATE NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... ADJUSTED LOW TEMPERATURES DOWN IN A SEVERAL AREAS PER GOING TRENDS. HAVING DOUBTS ON THE DEVELOPMENT OF WIDESPREAD STRATOCUMULUS AS SOME OF THE VARIOUS GUIDANCE SUGGESTS. LOWERED SKY COVER A CATEGORY IN SOME AREAS PER LATEST RAP SOUNDINGS. && .SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/... SUNDAY...THE FLOW ALOFT IS PRETTY MUCH ZONAL ACROSS THE LOWER 48 STATES...INCLUDING THE LOCAL ZONES. A LARGE AND ELONGATED RIDGE OF SURFACE HIGH PRESSURE WILL STRETCH FROM EAST OF NEW ENGLAND TO ACROSS THE SE STATES AND INTO THE GULF OF MEXICO AND BAY OF CAMPECHE. THE RESULTING SYNOPTIC FLOW VEERS AROUND TO THE SE AND SOUTH...WHICH PRODUCES TWO IMPORTANT FACTORS IN THE FORECAST PROCESS. FIRST IT PROVIDES THE AREA WITH SLIGHTLY WARMER CONDITIONS THAN TODAY...WHILE IT ALSO ALLOWS FOR A NOTICEABLE INCREASE IN LOWER LEVEL MOISTURE. AS 850 MB TEMPS CLIMB TO 8-9C AND LOW LEVEL THICKNESS VALUES RISE TO BETWEEN 1362 AND 1372 METERS FROM NE TO SW...IT ALLOWS FOR MAX TEMPS TO ACTUALLY RISE ABOVE EARLY APRIL NORMS. LOWER AND MIDDLE 70S WILL BE FAIRLY UNIFORM...EXCEPT FOR THE SHORELINE SECTIONS WHERE THE COOLING SEA BREEZE/ONSHORE TRAJECTORIES WILL LIMIT HIGHS TO ONLY THE MID OR UPPER 60S. THE MAJORITY OF THE MOISTURE IS TRAPPED BENEATH A STRONG SUBSIDENCE INVERSION AND RESTRICTED TO THE LOWEST 1-1.5 MILES OF THE ATMOSPHERE. WITH THE LOW AND MID LEVEL LAPSE RATES STEEPENING QUICKLY IN THE MORNING...WE/RE CONFIDENT THAT THIS WILL PRODUCE PERIODS OF STRATOCUMULUS AND FLAT CUMULUS CLOUD COVER THROUGHOUT THE DAY...EQUATING TO A PARTLY TO PERIODICALLY MOSTLY CLOUDY SKY COVER FORECAST. THERE ARE HINTS AT A COUPLE OF BRIEF SHOWERS FORMING ALONG THE INLAND PENETRATING SEA BREEZE WITH WEAK ISENTROPIC LIFT AND SOME UPWARD OMEGA FIELDS. BUT GIVEN LARGE DEW POINT DEPRESSIONS MOSTLY 15 DEGREES OR MORE...POPS WILL BE LIMITED TO ONLY A SILENT 10 PERCENT. SUNDAY NIGHT...ATLANTIC RIDGING WILL PERSIST OVERHEAD FROM THE EAST AND NE...WITH ZONAL FLOW UPSTAIRS. A WARM SE TO SOUTH SYNOPTIC FLOW AND AT LEAST SOME LOWER STRATOCUMULUS AND/OR STRATUS WILL PREVENT TEMPS FROM FALLING ANY LOWER THAN THE LOWER OR MIDDLE 50S INLAND FROM THE INTRACOASTAL...WITH A FEW UPPER 50S ON THE ISLANDS. FOG COULD BECOME A REALITY WITH HIGHER DEW POINTS...CONDENSATION PRESSURE DEFICITS FALLING TO 30-50 MB AND GEOSTROPHIC WINDS 10 KT OR LESS. HOWEVER...WE/LL BE HARD-PRESSED TO REACH OUR CROSS-OVER TEMPS IN MANY AREAS...THUS NO MORE THAN PATCHY FOG INLAND WELL LATE. MONDAY...THE MID AND UPPER PATTERN WILL START TO UNDERGO SOME CHANGES IN THE LARGER SCALE...AS A MORE AMPLIFIED TROUGH DEVELOPS OUT WEST. THE QUASI-ZONAL FLOW OVERHEAD LOCALLY WILL TRANSITION TO SHORT WAVE RIDGING DURING THE SECOND HALF OF THE DAY...RESULTING IN SOME NOTICEABLE MID LEVEL HEIGHT RISES. THAT ALONG WITH A CONTINUED INCREASE IN BOTH 850 MB TEMPS AND LOW LEVEL THICKNESSES WILL YIELD AN EVEN WARMER DAY. HIGHS WILL MAX OUT WITHIN A DEGREE OR TWO EITHER SIDE OF 80...ALTHOUGH THE ONSHORE FETCH AND SEA BREEZE CIRCULATION HOLDS COASTAL AREAS TO ONLY THE UPPER 60S TO PERHAPS 70. THE SYNOPTIC PATTERN WILL EXPERIENCE THE FORMATION OF A TYPICAL WARM SEASON RIDGE OF BERMUDA HIGH PRESSURE...THAT STRETCHES ACROSS MOST OF THE EAST AND SE PARTS OF THE NATION. THE SOUTHERLY LOW LEVEL FLOW AROUND THIS FEATURE WILL CONTINUE TO ADVECT SOME LOW LEVEL MOISTURE INTO THE REGION...BUT WITH THE LARGE SCALE SINKING AIR WE/LL BE HARD-PRESSED TO OBTAIN ANY SHOWER ACTIVITY ALONG THE SEA BREEZE. MONDAY NIGHT...ODDS FAVOR A GREATER POTENTIAL FOR FOG AS CONDENSATION PRESSURE DEFICITS LOWER TO AROUND 10-30 MB...DEW POINTS ARE EVEN HIGHER AND CROSS-OVER TEMPS WILL BE ACHIEVED IN MANY LOCALES. WEAK WARM ADVECTION WILL LIMIT MINIMUM TEMPS TO ONLY THE MID AND UPPER 50S MOST COMMUNITIES. TUESDAY...A MORE AMPLIFIED SCENARIO WILL UNFOLD ALOFT...WITH A DEEP POSITIVELY TILTED TROUGH IN THE ROCKIES TO BAJA CALIFORNIA...WHILE INCREASED RIDGING FORMS IN THE EAST. MID LEVEL HEIGHTS IN SOUTHERN SC AND SE GA RISE TO AROUND 5840 METERS...WITH A CONTINUED WARMING THROUGHOUT MUCH OF THE VERTICAL. BERMUDA HIGH PRESSURE IS AGAIN FIRMLY IN CONTROL...AND WITH ONLY LIMITED MOISTURE CONFINED IN THE LOWER LAYERS AND A STRONG SUBSIDENCE INVERSION OUR RAIN CHANCES ARE CLOSE TO ZERO. THERE IS ONLY A SUBTLE INCREASE IN LOW LEVEL THICKNESS...SO MAX TEMPS WILL BE A DEGREE OR TWO WARMER THAN ON MONDAY. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... DEEP LAYER RIDGING WILL SHIFT FARTHER INTO THE ATLANTIC WEDNESDAY AND THURSDAY. THE UPPER TROUGH FAR TO THE WEST WILL ALSO RAPIDLY SWING INTO THE MISSISSIPPI VALLEY AND SHIFT A COLD FRONT THROUGH THE OHIO/TENNESSEE VALLEYS. THERE REMAINS CONSIDERABLE TIMING DIFFERENCES IN MODEL SOLUTIONS REGARDING THE FRONTAL PASSAGE... WHICH COULD OCCUR AS EARLY AS THURSDAY AFTERNOON OR AS LATE AS FRIDAY NIGHT. DUE TO THIS UNCERTAINTY...PREFER TO KEEP MUCH OF THE LONG RANGE FORECAST AS PERSISTENCE UNTIL MODELS COME INTO BETTER AGREEMENT. HAVE THUS REMAINED RATHER GENERIC...INDICATING RAIN CHANCES IN THE 20 TO 30 PERCENT RANGE THURSDAY AND FRIDAY. WITH UNSEASONABLY WARM CONDITIONS CONTINUING PRIOR TO FRONTAL PASSAGE...THERE WILL BE ENOUGH TIME FOR LOW LEVEL INSTABILITY TO DEVELOP ACROSS THE AREA AS THE FRONT CROSSES THE REGION. THIS UNSTABLE AIR...WHEN COMBINED WITH AN IMPRESSIVE 40 TO 50 KT LOW LEVEL JET...COULD SUPPORT STRONG THUNDERSTORMS LATE THIS WEEK. CONDITIONS BY SATURDAY COULD BE IMPROVING...AS EVEN THE SLOWEST MODEL SOLUTIONS HAVE THE FRONT MOVING OFF THE COAST BY THE AFTERNOON HOURS. EXPECT A SLIGHT COOL DOWN TOWARD SEASONAL NORMALS IN THE MID 70S BEHIND THE FRONT LATE IN THE PERIOD. && .AVIATION /05Z SUNDAY THROUGH THURSDAY/... GENERALLY VFR. INCREASING MOISTURE FROM OFF THE ATLANTIC WILL LIKELY SUPPORT SOME STRATOCUMULUS THROUGH SUNRISE. ITS STILL UNCLEAR AT THIS POINT HOW WIDESPREAD THESE CLOUDS WILL BECOME BUT LATEST RAP DATA SUGGESTS ANY CIGS THAT ARE ESTABLISHED WILL LIKELY REMAIN LOW-END VFR...MAINLY AT KSAV WHERE THE RISK FOR LOW CLOUDS WILL BE THE GREATEST. WILL CARRY VFR CONDITIONS AT BOTH KCHS/KSAV FOR THE NEXT 24 HOURS. WILL LIKELY SEE A PERIOD OF GUSTY WINDS IN THE WAKE OF THE AFTERNOON...POSSIBLY REACHING AS HIGH AS 15-18 KT. EXTENDED AVIATION OUTLOOK...POSSIBLE FLIGHT RESTRICTIONS IN LIGHT FOG/MIST LATE AT NIGHT AND IN THE MORNING SUNDAY NIGHT THROUGH WEDNESDAY. && .MARINE... THE MAIN CONCERN OVERNIGHT IS SEA HEIGHTS OVER OUR OUTER GEORGIA WATERS RUNNING POSSIBLY NEAR ADVISORY LEVELS FOR A WHILE. STEADY NE-E FETCH AND SEAS OBSERVED GREATER THAN MODEL WAVE GUIDANCE WELL OFF THE S CAROLINA COAST ARE PROBABLY TIPS WE HAVE SOME 6 FOOTERS OUT THERE CLOSER TO THE GULF STREAM IN AMZ374. MODELS ALLOW THE FLOW TO LAY DOWN OVERNIGHT AND WE HAVE OPTED NOT TO RAISE A SMALL CRAFT ADVISORY DURING THIS EVENING GIVEN FORECAST MODEL TRENDS. STILL A NICE SWELL COMPONENT AND 4-5 FT LOOKING COMMON OVERNIGHT BEYOND 20 NM. OTHERWISE...FLOW LOCKED NE TONIGHT BY THE COLDER SHELF WATERS WITH SPEEDS 15 KT OR LESS AND SEAS 3 TO 4 FT. THE LOCAL WATERS WILL LIE UNDER THE WESTERN PORTION OF A LARGE AND FAIRLY STRONG RIDGE OF ATLANTIC HIGH PRESSURE THROUGHOUT THE UPCOMING WEEK. THE ANTICYCLONIC SE AND SOUTH CIRCULATION AROUND THE HIGH WILL BECOME ENHANCED AT TIMES BY AFTERNOON/EVENING SEA BREEZE CIRCULATIONS...BUT NOTHING MORE THAN ABOUT 10 OR 15 KT WINDS AND 2-4 FOOT SEAS THROUGH WEDNESDAY. BY THURSDAY THERE DOES APPEAR TO BE SOME TIGHTENING OF THE GRADIENT BETWEEN THE HIGH AND AN APPROACHING COLD FRONT...AND WINDS AND/OR SEAS COULD BUILD CLOSE TO ADVISORY LEVELS LATE IN THE FORECAST PERIOD. RIP CURRENTS...DESPITE WATER TEMPS ONLY NEAR 60 AND AIR TEMPS NOT MUCH HIGHER...THERE ARE STILL PEOPLE FLOCKING TO THE BEACH. AND SOME ARE VENTURING INTO THE SURF...WITH REPORTS OF RIP CURRENTS AND RESCUES AT TYBEE BEACH EARLIER TODAY. WITH ONSHORE WINDS AT 10-15 MPH AND AROUND 2 FOOT SWELLS EVERY 8 SECONDS WE/LL BE AT THE HIGH-END RANGE OF THE LOW RISK OF RIP CURRENTS SUNDAY. IF SWELLS ARE ABLE TO OBTAIN 3 FEET...A MODERATE RISK WOULD BE REQUIRED. BEACH GOERS ARE REMINDED THAT EVEN DURING A LOW RISK THAT RIP CURRENTS CAN STILL OCCUR. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ ST
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
258 AM CDT SUN APR 7 2013 .DISCUSSION... 912 PM CDT SHOWERS CONTINUE TO MOVE ACROSS NORTHERN ILLINOIS THIS EVENING. HOWEVER...A CLUSTER OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED OVER THE PAST COUPLE HOURS ACROSS EASTERN IOWA. THIS ACTIVITY IS FIRING JUST AHEAD OF A SURFACE COLD FRONT IN AN AREA OF INCREASED ASCENT AHEAD OF A RATHER STOUT MID LEVEL SHORT WAVE...CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING EASTWARD ACROSS SOUTHEASTERN IOWA. THE 00 UTC SOUNDING OUT OF KDVN INDICATES THAT THE AIRMASS IN WHICH THIS ACTIVITY IS DEVELOPING IN POSSES DECENT MID LEVEL LAPSE RATES. HOWEVER...OVERALL INSTABILITY IS RATHER LACK LUSTER...WITH MUCAPE VALUES ONLY UP TO AROUND 100 J/KG. IN SPITE OF THIS...THE STRONGER FORCING FOR ASCENT COMPLEMENTS OF THE MID LEVEL WAVE AND MOISTURE CONVERGENCE IN THE LOWER LEVELS...IS ABLE TO TAKE ADVANTAGE OF THE STEEP LAPSE RATES TO RESULT IN THUNDERSTORMS. THIS ACTIVITY WILL LIKELY MAINTAIN ITSELF FOR THE NEXT FEW HOURS AS IT PUSHES EASTWARD ACROSS NORTHERN ILLINOIS. THERE COULD EVEN BE SOME SMALL HAIL AND SOME GUSTY WINDS IN SOME OF THE STRONGEST STORMS GIVEN THE DRIER AIR IN THE LOWEST FEW THOUSAND FEET. THIS ACTIVITY SHOULD END OVERNIGHT WITH WINDS BECOMING WESTERLY IN THE WAKE OF THE FRONTAL PASSAGE. KJB //PREV DISCUSSION... 259 PM CDT THERE ARE NUMEROUS CHALLENGES WITH THE FORECAST AS THE PATTERN TRANSITIONS TO A MORE ACTIVE ONE...BEGINNING WITH SHOWERS AND SOME SPORADIC THUNDER THIS EVENING AND THEN CARRYING THROUGH THE MIDDLE OF NEXT WEEK. IN ADDITION...THE LIKELY LOCATION OF THE AREA RELATIVE TO SYNOPTIC FEATURES WILL ALLOW FOR TEMPERATURES TO BE HEAVILY DEPENDENT ON CLOUD COVER AND RAIN...ALONG WITH LAKE INDUCED COOLING AT LEAST A FEW OF THE UPCOMING SEVERAL DAYS. NEAR TERM INTO TONIGHT...A FAST PACED BUT MORE AMPLIFIED UPPER LEVEL PATTERN IS ESTABLISHED OVER THE CENTRAL U.S. THIS AFTERNOON WITH A WELL-DEFINED UPPER WAVE ON WATER VAPOR ADVANCING EASTWARD FROM WESTERN IA. A 1000 MB SURFACE LOW REFLECTION ACROSS SOUTHERN MN HAS DEVELOPED AND HELPED TO ESTABLISH STRONG RETURN FLOW WITH WIND GUSTS TO 40 TO 45 MPH AT SEVERAL SITES. THESE WINDS SHOULD DIMINISH GRADUALLY THROUGH THE EVENING HOURS. MOISTURE RETURN HAS STRUGGLED HOWEVER...BOTH AT THE SURFACE AND IN THE DEEP LAYER PER OBSERVATIONS AND PWAT ANALYSIS AND IS A REASON SHOWER COVERAGE IS LIKELY TO BE MORE LIMITED THAN IT COULD BE GIVEN THE UPPER FORCING AHEAD OF THIS WAVE...AND IT WILL TAKE SOME TIME FOR THE VERY DRY LOWER ATMOSPHERE TO SATURATE. A NARROW CORRIDOR OF 700-900 MB MOISTURE TRANSPORT ALONG A MID-LEVEL JET HAS STILL HELPED TO INCREASE ECHOES UPSTREAM DURING THE FIRST HALF OF THE AFTERNOON AND THIS WILL LIKELY BE JUST ENOUGH TO CONTINUE DOING SUCH WITH STEEPENING MID-LEVEL LAPSE RATES IN CONCERT WITH THE NARROW MOISTURE CONVERGENCE. MOST OF THE HIGH-RES CONVECTIVE ALLOWING MODELS PREDICT AN INCREASE IN CONVECTIVE-TYPE ECHOES ACROSS NORTH CENTRAL IL BETWEEN 23Z AND 03Z SHIFTING EASTWARD AND FADING SLOWLY THROUGH EARLY OVERNIGHT AS THE FRONT SHIFTS EAST. WITH SEVERAL OF THESE GUIDANCE MEMBERS INDICATING HIGHER REFLECTIVITY AND A NARROW CORRIDOR OF 200-400 J/KG OF MUCAPE PER THE RAP ALONG THE FRONT...WOULD EXPECT A FEW STORMS WITHIN THE GENERAL SHOWERS. HAVE ADAPTED HOURLY POPS THROUGH THIS EVENING PERIOD OF THE FORECAST. AS PREVIOUS FORECAST DID KEEP MOST OF TONIGHTS TEMPERATURE DROP AFTER THE FRONTAL PASSAGE FROM WEST TO EAST. SUNDAY...HIGH PRESSURE STILL LOOKS TO BRIEFLY PREVAIL FOR THIS PERIOD. THE MOST NOTEWORTHY ASPECT ABOUT THIS IS IT LOOKS TO LINE UP DOWN THE AXIS OF LAKE MICHIGAN BY MIDDAY AND ALLOW FOR A FAIRLY STOUT LAKE BREEZE. THIS WILL BE AIDED BY THE FACT THAT TEMPERATURES SHOULD MODERATE NICELY ON SUNDAY OVER LAND DUE TO ONLY A SMALL WINDOW OF COLD AIR ADVECTION BEHIND THE FRONT TONIGHT AND A DRY AIR MASS AND PREDICTED SUNSHINE DURING SUNDAY. THE TEMPERATURE AND PRESSURE DIFFERENCES WITHIN A LIGHT WIND FIELD SHOULD DRIVE A STRONG LAKE BREEZE...AND THE AFTERNOON TEMPERATURE DROP FOR DOWNTOWN CHICAGO AND OTHER NEAR LAKE AREAS MAY BE AS MUCH AS 15 DEGREES. SUNDAY NIGHT AND MONDAY...AN ACTIVE WEST-TO-EAST PACIFIC JET OVER 120 KT AS SEEN ON HEMISPHERIC WATER VAPOR TODAY WILL DIG ITS WAY INTO THE WESTERN U.S. WITH TROUGH DEVELOPMENT AND UPSTREAM SOUTHWEST FLOW OVER THE MIDWEST. A LEAD IMPULSE IN THIS FLOW IS WELL PREDICTED ON GUIDANCE TO PASS OVER THE AREA DURING LATE SUNDAY NIGHT INTO MONDAY MORNING. THIS LOOKS TO TIGHTEN AN UPPER LEVEL WARM FRONT AND ALLOW FOR SATURATED ISENTROPIC LIFT FOR RAIN SHOWERS. ELEVATED INSTABILITY DOES INCREASE AS THE WARM NOSE BUILDS IN WITHIN THE LOWER LEVELS...AND START THUNDER IN THIS FORECAST PERIOD ITS TOO TOUGH TO DISCERN A PERIOD WHERE THERE WOULD NOT BE A THUNDER CHANCE ALL THE WAY THROUGH WEDNESDAY NIGHT. IN THE WAKE OF THIS LEAD IMPULSE HEIGHTS LOOK TO BUILD ON MONDAY AS THE PRIMARY TROUGH DEVELOPS. ITS A LITTLE INTERESTING AS THERE SHOULD BE A SURFACE WARM FRONT...POSSIBLY DIABATICALLY ENHANCED...LAID OUT SOMEWHERE IN THE CENTRAL IL TO NORTHERN IL REGION. THE ONLY THING IS WITH SHORT WAVE RIDGING HINTED AT THIS FEATURE APPEARS TO BE FAIRLY BENIGN...BUT SOMETHING TO KEEP AN EYE ON. MIDWEEK...AN ACTIVE PERIOD HERE AS PROLONGED SURFACE CYCLOGENESIS BEGINS OVER THE SOUTHERN PLAINS MONDAY NIGHT AND CONTINUES THROUGH TUESDAY WITH THE SURFACE WAVE ADVANCING ENE ON WED. MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THIS...LATCHING MORE ONTO AN EC SOUTHERN SOLUTION. HAVE CONTINUED TO LEAN THAT WAY WITH THE FORECAST WHICH MEANS INHIBITING TEMPERATURES ON WHAT COULD BE GIVEN 850MB TEMPERATURES CLIMBING TO 8C-12C...ESPECIALLY NORTH OF I-80. WITH FLOW OFF THE LAKE TUESDAY AND WEDNESDAY DUE TO THE LOW BEING SOUTHWEST OF THE AREA...TEMPERATURES NEAR THE LAKE WILL REMAIN COOLER. ALSO THIS FORECAST PATTERN MEANS LIKELY SEVERAL BOUTS OF PRECIP WITH THE PROXIMITY OF THE ELEVATED WARM/STATIONARY FRONT. THE 06.12 GFS AND EC RUNS BOTH HAVE OVER TWO AND A HALF INCHES OF RAIN FORECAST AREA WIDE FROM SUNDAY NIGHT THROUGH THURSDAY. WHILE IT IS CHALLENGING TO FOCUS ANY WINDOW FOR CATEGORICAL POPS...IT WOULD SEEM WEDNESDAY AND WEDNESDAY NIGHT WOULD BE THE MOST FAVORED PERIODS FOR STRONGER DYNAMIC FORCING AND POSSIBLY MORE ROBUST ELEVATED CONVECTION WITH THE LARGE SCALE UPPER TROUGH MOVING EASTWARD. COOLING BEHIND THE FRONT LOOKS SOMEWHAT STRONG AND THERE IS A POTENTIAL TO SEE SOME MIX IN THE WAKE OF THE FRONT...BUT CONFIDENCE IS VERY LOW ON HOW THIS SYSTEM WILL EVOLVE AS IT LIFTS OUT. BEYOND...HAVE GONE PRIMARILY WITH A MODEL CONSENSUS AT THE END OF NEXT WEEK AS THE UPPER FLOW PATTERN WORKS FROM BRIEFLY NORTHWEST BACK TO WEST. TEMPERATURES SHOULD GRADUALLY MODERATE BUT CONFIDENCE IS LOW ON PRECIP CHANCES AS THE PATTERN STILL LOOKS DISTURBED. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * MVFR CIGS OVERNIGHT INTO SUNDAY MORNING * WIND SHIFT TO EASTERLY SUNDAY AFTERNOON IZZI //DISCUSSION...UPDATED 06Z... COLD FRONT MOVING THROUGH THE REGION AT THIS TIME WITH SHRA/TSRA MOVING EAST OF THE REGION. EXPANDING BANK OF STRATUS HAS BEEN NOTED ON SATELLITE IMAGERY UPSTREAM OVER WI/IA INTO NW IL WITH GUIDANCE SUGGESTING THIS SHOULD CONTINUE TO EXPAND EAST INTO THE TERMINALS OVERNIGHT. DOES APPEAR THAT MIXING/HEATING SHOULD HELP ERODE THE STRATUS SUNDAY MORNING...THOUGH TIMING OF SCATTERING OUT CIGS IS UNCERTAIN. WESTERLY WINDS SHOULD GUST OCCASIONALLY TO 15-20KT OVERNIGHT BEFORE EASING SUNDAY MORNING. PRESSURE FALLS OVER THE PLAINS EXPECTED TO RESULT IN AN ABRUPT SHIFT TO EASTERLY WINDS SUNDAY EVENING...WITH THE TIMING OF THAT WIND SHIFT LIKELY A BIT EARLIER AT ORD/MDW/GYY AS COLLAPSING GRADIENT IN THE AFTERNOON SHOULD ALLOW FOR ROBUST LAKE BREEZE DEVELOPMENT. NEXT DISTURBANCE LIKELY TO APPROACH THE REGION TOWARD THE END OF OR JUST BEYOND THE ORD 30 TAF HOUR PERIOD WITH ADDITIONAL SHRA/TSRA EXPECTED AT THAT TIME. IZZI //ORD AND MDW CONFIDENCE...UPDATED 06Z... * MEDIUM-HIGH CONFIDENCE IN LOW END MVFR CIGS OVERNIGHT INTO SUN AM * LOW-MEDIUM CONFIDENCE ON TIMING OF IMPROVEMENT TO VFR SUNDAY MORNING * HIGH CONFIDENCE ON WIND SHIFT TO EAST SUN PM IZZI //OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z... MONDAY...SHRA/TSRA LIKELY EARLY. MVFR/BRIEF IFR POSSIBLE EARLY. TUESDAY THROUGH THURSDAY NIGHT...PERIODIC CHANCE FOR SHRA/TSRA. PERIODIC MVFR CIGS/VSBY LIKELY WITH BRIEF IFR POSSIBLE. FRIDAY...PROBABLE VFR. MDB && .MARINE... 258 AM CDT WEAK HIGH PRESSURE WILL BUILD INTO THE REGION TODAY WITH WINDS SUBSIDING FAIRLY QUICKLY...BEFORE DEVELOPING LAKE BREEZE CIRCULATION GETS A BOOST FROM GRADUALLY INCREASING SYNOPTIC EASTERLY GRADIENT THIS AFTERNOON. EASTERLY WINDS LIKELY TO FRESHEN UP LATE TONIGHT INTO MONDAY MORNING...ESPECIALLY SOUTHERN PORTIONS OF THE LAKE. FRONT WILL ATTEMPT TO MOVE NORTH MONDAY...BUT MAY GET HUNG UP ALONG OR JUST OFFSHORE WITH MORE OF AN EAST OR SOUTHEAST WIND LIKELY OVER OPEN WATERS. SURGE OF HIGHER DEWPOINTS OVER THE COLD LAKE WITH THE FRONT NEARBY COULD RESULT IN SOME DENSE MARINE FOG MONDAY NIGHT. FOG SHOULD DISSIPATE TUESDAY ASSUMING THE NORTHEAST WINDS INCREASE AS FORECAST. THERE REMAINS SOME DISAGREEMENT AMONG THE MODELS WITH REGARDS TO FRONTAL PLACEMENT...BUT THE MOST RELIABLE MODELS ARE GENERALLY KEEPING FRONT SOUTH OF THE LAKE MONDAY NIGHT THROUGH END OF THE WEEK WITH FAIRLY STRONG NORTHEASTERLY FLOW EXPECTED TO GENERALLY PREVAIL. IZZI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 AM SUNDAY. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
246 AM CDT SUN APR 7 2013 .DISCUSSION... ISSUED 245 AM CDT SUN APR 7 2013 COLD FRONT HAS PUSHED THROUGH ABOUT THE NORTHWEST HALF OF THE CWA AS OF 2 AM...EXTENDING ROUGHLY FROM BLOOMINGTON TO JACKSONVILLE. NARROW BAND OF SHOWERS ALONG I-70 IS WHAT IS LEFT FROM THE PRE- FRONTAL CONVECTION WHICH BROUGHT SOME LOCALLY HEAVY SHOWERS LAST EVENING ACROSS THE NORTHERN CWA. LARGE STRATUS/STRATOCUMULUS DECK BEHIND THE FRONT HAS BEEN OOZING SOUTHWARD PER FOG CHANNEL SATELLITE IMAGERY AND HAS REACHED MARSHALL COUNTY...BUT HAS NOT MADE MUCH FURTHER SOUTHWARD PROGRESSION OVER THE LAST COUPLE HOURS. TIMING OF RAIN CHANCES OVER THE NEXT FEW DAYS CONTINUES TO BE A CHALLENGE...ALONG WITH THE WARM TEMPERATURES. SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT... LATEST MODEL GUIDANCE SHOWING WINDS ALREADY SWINGING BACK TO THE SOUTHEAST BY AFTERNOON ACROSS MUCH OF THE FORECAST AREA...WITH THE BOUNDARY LIFTING BACK INTO NORTHERN ILLINOIS OVERNIGHT. MOST OF THE CWA SHOULD BE ABLE TO REACH 70 DEGREES EXCEPT FOR PERHAPS THE NORTH...ALTHOUGH A FASTER FRONTAL PASSAGE WOULD ALLOW SUCH TEMPERATURES THERE AS WELL. CURRENTLY LOOKS LIKE THE DAYTIME SHOULD BE DRY WITH PERHAPS A COUPLE SHOWERS SOUTH OF I-70 LATE AFTERNOON...WITH NEXT SURGE OF PRECIPITATION SPREADING IN FROM THE SOUTHWEST IN THE EVENING AHEAD OF THE NEXT SHORTWAVE IN THE PLAINS. HAVE RAMPED RAIN CHANCES UP INTO THE CATEGORICAL RANGE OF NEAR 80 PERCENT ALONG AND WEST OF THE ILLINOIS RIVER AFTER MIDNIGHT...WITH LIKELY POPS IN MOST OTHER AREAS NORTH OF I-70. MUCH OF THE RAIN SHOULD EXIT THE AREA MONDAY MORNING...ALLOWING TEMPS TO RISE BACK TO AROUND 70 WITH A DECENT SOUTHERLY FLOW. UPPER LOW CURRENTLY SPINNING WEST OF BRITISH COLUMBIA SHOULD DROP SOUTHEASTWARD INTO THE 4-CORNERS REGION BY MONDAY EVENING. EVENING MODELS COMING INTO SOMEWHAT BETTER AGREEMENT WITH THE EVOLUTION OF THIS FEATURE THROUGH THE MIDDLE OF THE WEEK...LIFTING IT NORTHWARD TO NEAR SOUTH DAKOTA BY WEDNESDAY MORNING WITH A SURFACE LOW TRACKING NORTHEAST INTO IOWA. CONVECTION EXPECTED TO INCREASE AGAIN MONDAY NIGHT AND WANE TUESDAY AFTERNOON...BEFORE RAMPING UP AGAIN AS THE MAIN COLD FRONT APPROACHES. HAVE GONE WITH LIKELY POPS ACROSS THE WEST TUESDAY NIGHT...EVERYWHERE WEDNESDAY...AND INCREASED THEM TO CATEGORICAL FROM I-57 EAST WEDNESDAY EVENING AS THE FRONT PASSES. IN TERMS OF SEVERE POTENTIAL...THE FRONT WILL BE CROSSING DURING A FAVORABLE TIME OF THE DAY ON WEDNESDAY...WITH MUCAPES INCREASING TO AROUND 1500 J/KG WEDNESDAY AFTERNOON IN THE EASTERN CWA AND LOW-LEVEL WINDS RAMPING UP TO AROUND 45 KNOTS AT 925 MB. LATEST SPC DAY3 CONVECTIVE OUTLOOK DOES SPREAD SLIGHT CHANCES OF SEVERE WEATHER ACROSS THE WESTERN CWA WITH SLIGHTLY LOWER CHANCES ACROSS THE EAST. FORECAST SOUNDINGS WOULD FAVOR MORE OF A WIND THREAT THIS FAR EAST WITH UNIDIRECTIONAL WIND PROFILES IN THE LOWER LEVELS. LONG TERM...THURSDAY THROUGH SATURDAY... LINGERING SHOWERS ON THURSDAY WILL DECREASE FROM WEST TO EAST AS THE FRONT PULLS AWAY. HOWEVER...LATEST GFS AND ECMWF MODELS SWING THE REMAINING UPPER LOW THROUGH IOWA AND WISCONSIN...SO SOME POTENTIAL FOR COLD-CORE SHOWERS CONTINUES MAINLY ACROSS THE NORTHERN CWA INTO AFTERNOON...ALTHOUGH BEST CHANCES WILL BE CLOSER TO THE LOW. THE REMAINDER OF THE WEEK WILL MAINLY BE QUIET...AS HIGH PRESSURE SLOWLY PUSHES EASTWARD THROUGH THE REGION. WILL SEE A COUPLE OF COOL DAYS THURSDAY AND FRIDAY...WITH TEMPERATURES FRIDAY MORNING GETTING CLOSE TO FREEZING ACROSS THE NORTHWEST CWA. GEELHART && .AVIATION... ISSUED 1154 PM CDT SAT APR 6 2013...FOR THE 06Z TAFS SOME SHOWERS MAY AFFECT CMI FOR THE FIRST HALF HOUR OF THE TAF PERIOD...OTHERWISE THE TERMINAL SITES SHOULD REMAIN DRY OVER THE NEXT 24 HOURS. THE COLD FRONT WILL PASS ACROSS DEC/CMI OVER THE NEXT HOUR OR TWO...SO WINDS SHOULD DIMINISH FROM STRONG SOUTH TO LIGHTER SOUTHWEST AROUND 12-14KT. LATER TONIGHT ALL TAF SITES SHOULD SEE WEST WINDS AROUND 10KT. SOME MVFR CLOUDS ARE EXPECTED TO APPROACH OUR NORTHERN COUNTIES...WITH PIA AND BMI POSSIBLY SEEING SOME OF THAT. LIGHT FOG MAY EVEN AFFECT PIA AND BMI. I ADDED A TEMPO FOR BKN015 FOR 12Z TO 15Z TO MATCH THE HRRR OUTPUT FOR THAT TIME FRAME. SHIMON && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1231 AM CDT SUN APR 7 2013 .DISCUSSION... 912 PM CDT SHOWERS CONTINUE TO MOVE ACROSS NORTHERN ILLINOIS THIS EVENING. HOWEVER...A CLUSTER OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED OVER THE PAST COUPLE HOURS ACROSS EASTERN IOWA. THIS ACTIVITY IS FIRING JUST AHEAD OF A SURFACE COLD FRONT IN AN AREA OF INCREASED ASCENT AHEAD OF A RATHER STOUT MID LEVEL SHORT WAVE...CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING EASTWARD ACROSS SOUTHEASTERN IOWA. THE 00 UTC SOUNDING OUT OF KDVN INDICATES THAT THE AIRMASS IN WHICH THIS ACTIVITY IS DEVELOPING IN POSSES DECENT MID LEVEL LAPSE RATES. HOWEVER...OVERALL INSTABILITY IS RATHER LACK LUSTER...WITH MUCAPE VALUES ONLY UP TO AROUND 100 J/KG. IN SPITE OF THIS...THE STRONGER FORCING FOR ASCENT COMPLEMENTS OF THE MID LEVEL WAVE AND MOISTURE CONVERGENCE IN THE LOWER LEVELS...IS ABLE TO TAKE ADVANTAGE OF THE STEEP LAPSE RATES TO RESULT IN THUNDERSTORMS. THIS ACTIVITY WILL LIKELY MAINTAIN ITSELF FOR THE NEXT FEW HOURS AS IT PUSHES EASTWARD ACROSS NORTHERN ILLINOIS. THERE COULD EVEN BE SOME SMALL HAIL AND SOME GUSTY WINDS IN SOME OF THE STRONGEST STORMS GIVEN THE DRIER AIR IN THE LOWEST FEW THOUSAND FEET. THIS ACTIVITY SHOULD END OVERNIGHT WITH WINDS BECOMING WESTERLY IN THE WAKE OF THE FRONTAL PASSAGE. KJB //PREV DISCUSSION... 259 PM CDT THERE ARE NUMEROUS CHALLENGES WITH THE FORECAST AS THE PATTERN TRANSITIONS TO A MORE ACTIVE ONE...BEGINNING WITH SHOWERS AND SOME SPORADIC THUNDER THIS EVENING AND THEN CARRYING THROUGH THE MIDDLE OF NEXT WEEK. IN ADDITION...THE LIKELY LOCATION OF THE AREA RELATIVE TO SYNOPTIC FEATURES WILL ALLOW FOR TEMPERATURES TO BE HEAVILY DEPENDENT ON CLOUD COVER AND RAIN...ALONG WITH LAKE INDUCED COOLING AT LEAST A FEW OF THE UPCOMING SEVERAL DAYS. NEAR TERM INTO TONIGHT...A FAST PACED BUT MORE AMPLIFIED UPPER LEVEL PATTERN IS ESTABLISHED OVER THE CENTRAL U.S. THIS AFTERNOON WITH A WELL-DEFINED UPPER WAVE ON WATER VAPOR ADVANCING EASTWARD FROM WESTERN IA. A 1000 MB SURFACE LOW REFLECTION ACROSS SOUTHERN MN HAS DEVELOPED AND HELPED TO ESTABLISH STRONG RETURN FLOW WITH WIND GUSTS TO 40 TO 45 MPH AT SEVERAL SITES. THESE WINDS SHOULD DIMINISH GRADUALLY THROUGH THE EVENING HOURS. MOISTURE RETURN HAS STRUGGLED HOWEVER...BOTH AT THE SURFACE AND IN THE DEEP LAYER PER OBSERVATIONS AND PWAT ANALYSIS AND IS A REASON SHOWER COVERAGE IS LIKELY TO BE MORE LIMITED THAN IT COULD BE GIVEN THE UPPER FORCING AHEAD OF THIS WAVE...AND IT WILL TAKE SOME TIME FOR THE VERY DRY LOWER ATMOSPHERE TO SATURATE. A NARROW CORRIDOR OF 700-900 MB MOISTURE TRANSPORT ALONG A MID-LEVEL JET HAS STILL HELPED TO INCREASE ECHOES UPSTREAM DURING THE FIRST HALF OF THE AFTERNOON AND THIS WILL LIKELY BE JUST ENOUGH TO CONTINUE DOING SUCH WITH STEEPENING MID-LEVEL LAPSE RATES IN CONCERT WITH THE NARROW MOISTURE CONVERGENCE. MOST OF THE HIGH-RES CONVECTIVE ALLOWING MODELS PREDICT AN INCREASE IN CONVECTIVE-TYPE ECHOES ACROSS NORTH CENTRAL IL BETWEEN 23Z AND 03Z SHIFTING EASTWARD AND FADING SLOWLY THROUGH EARLY OVERNIGHT AS THE FRONT SHIFTS EAST. WITH SEVERAL OF THESE GUIDANCE MEMBERS INDICATING HIGHER REFLECTIVITY AND A NARROW CORRIDOR OF 200-400 J/KG OF MUCAPE PER THE RAP ALONG THE FRONT...WOULD EXPECT A FEW STORMS WITHIN THE GENERAL SHOWERS. HAVE ADAPTED HOURLY POPS THROUGH THIS EVENING PERIOD OF THE FORECAST. AS PREVIOUS FORECAST DID KEEP MOST OF TONIGHTS TEMPERATURE DROP AFTER THE FRONTAL PASSAGE FROM WEST TO EAST. SUNDAY...HIGH PRESSURE STILL LOOKS TO BRIEFLY PREVAIL FOR THIS PERIOD. THE MOST NOTEWORTHY ASPECT ABOUT THIS IS IT LOOKS TO LINE UP DOWN THE AXIS OF LAKE MICHIGAN BY MIDDAY AND ALLOW FOR A FAIRLY STOUT LAKE BREEZE. THIS WILL BE AIDED BY THE FACT THAT TEMPERATURES SHOULD MODERATE NICELY ON SUNDAY OVER LAND DUE TO ONLY A SMALL WINDOW OF COLD AIR ADVECTION BEHIND THE FRONT TONIGHT AND A DRY AIR MASS AND PREDICTED SUNSHINE DURING SUNDAY. THE TEMPERATURE AND PRESSURE DIFFERENCES WITHIN A LIGHT WIND FIELD SHOULD DRIVE A STRONG LAKE BREEZE...AND THE AFTERNOON TEMPERATURE DROP FOR DOWNTOWN CHICAGO AND OTHER NEAR LAKE AREAS MAY BE AS MUCH AS 15 DEGREES. SUNDAY NIGHT AND MONDAY...AN ACTIVE WEST-TO-EAST PACIFIC JET OVER 120 KT AS SEEN ON HEMISPHERIC WATER VAPOR TODAY WILL DIG ITS WAY INTO THE WESTERN U.S. WITH TROUGH DEVELOPMENT AND UPSTREAM SOUTHWEST FLOW OVER THE MIDWEST. A LEAD IMPULSE IN THIS FLOW IS WELL PREDICTED ON GUIDANCE TO PASS OVER THE AREA DURING LATE SUNDAY NIGHT INTO MONDAY MORNING. THIS LOOKS TO TIGHTEN AN UPPER LEVEL WARM FRONT AND ALLOW FOR SATURATED ISENTROPIC LIFT FOR RAIN SHOWERS. ELEVATED INSTABILITY DOES INCREASE AS THE WARM NOSE BUILDS IN WITHIN THE LOWER LEVELS...AND START THUNDER IN THIS FORECAST PERIOD ITS TOO TOUGH TO DISCERN A PERIOD WHERE THERE WOULD NOT BE A THUNDER CHANCE ALL THE WAY THROUGH WEDNESDAY NIGHT. IN THE WAKE OF THIS LEAD IMPULSE HEIGHTS LOOK TO BUILD ON MONDAY AS THE PRIMARY TROUGH DEVELOPS. ITS A LITTLE INTERESTING AS THERE SHOULD BE A SURFACE WARM FRONT...POSSIBLY DIABATICALLY ENHANCED...LAID OUT SOMEWHERE IN THE CENTRAL IL TO NORTHERN IL REGION. THE ONLY THING IS WITH SHORT WAVE RIDGING HINTED AT THIS FEATURE APPEARS TO BE FAIRLY BENIGN...BUT SOMETHING TO KEEP AN EYE ON. MIDWEEK...AN ACTIVE PERIOD HERE AS PROLONGED SURFACE CYCLOGENESIS BEGINS OVER THE SOUTHERN PLAINS MONDAY NIGHT AND CONTINUES THROUGH TUESDAY WITH THE SURFACE WAVE ADVANCING ENE ON WED. MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THIS...LATCHING MORE ONTO AN EC SOUTHERN SOLUTION. HAVE CONTINUED TO LEAN THAT WAY WITH THE FORECAST WHICH MEANS INHIBITING TEMPERATURES ON WHAT COULD BE GIVEN 850MB TEMPERATURES CLIMBING TO 8C-12C...ESPECIALLY NORTH OF I-80. WITH FLOW OFF THE LAKE TUESDAY AND WEDNESDAY DUE TO THE LOW BEING SOUTHWEST OF THE AREA...TEMPERATURES NEAR THE LAKE WILL REMAIN COOLER. ALSO THIS FORECAST PATTERN MEANS LIKELY SEVERAL BOUTS OF PRECIP WITH THE PROXIMITY OF THE ELEVATED WARM/STATIONARY FRONT. THE 06.12 GFS AND EC RUNS BOTH HAVE OVER TWO AND A HALF INCHES OF RAIN FORECAST AREA WIDE FROM SUNDAY NIGHT THROUGH THURSDAY. WHILE IT IS CHALLENGING TO FOCUS ANY WINDOW FOR CATEGORICAL POPS...IT WOULD SEEM WEDNESDAY AND WEDNESDAY NIGHT WOULD BE THE MOST FAVORED PERIODS FOR STRONGER DYNAMIC FORCING AND POSSIBLY MORE ROBUST ELEVATED CONVECTION WITH THE LARGE SCALE UPPER TROUGH MOVING EASTWARD. COOLING BEHIND THE FRONT LOOKS SOMEWHAT STRONG AND THERE IS A POTENTIAL TO SEE SOME MIX IN THE WAKE OF THE FRONT...BUT CONFIDENCE IS VERY LOW ON HOW THIS SYSTEM WILL EVOLVE AS IT LIFTS OUT. BEYOND...HAVE GONE PRIMARILY WITH A MODEL CONSENSUS AT THE END OF NEXT WEEK AS THE UPPER FLOW PATTERN WORKS FROM BRIEFLY NORTHWEST BACK TO WEST. TEMPERATURES SHOULD GRADUALLY MODERATE BUT CONFIDENCE IS LOW ON PRECIP CHANCES AS THE PATTERN STILL LOOKS DISTURBED. MTF && .FIRE WEATHER... 328 AM...EASTERLY FLOW HAS MAINTAINED MUCH DRIER AIR ACROSS THE REGION AND EXPECT A SLOW RETURN OF LOW LEVEL MOISTURE ACROSS THE AREA TODAY. IT APPEARS DEWPOINTS WILL INCREASE BACK INTO THE 40S...BUT PROBABLY NOT UNTIL LATE AFTERNOON ACROSS WESTERN IL AND THE REST OF THE AREA THIS EVENING. THUS MINIMUM RH VALUES TODAY WILL LIKELY BE IN THE 35-40 PERCENT RANGE AND COULD POSSIBLY DIP INTO THE 30-35 PERCENT RANGE. WHILE THESE EXPECTED VALUES WILL REMAIN ABOVE RED FLAG CRITERIA OF 25 PERCENT...SOUTHERLY WINDS ARE EXPECTED TO QUICKLY INCREASE THIS MORNING WITH GUSTS AS HIGH AS 40 MPH FROM LATE MORNING THROUGH SUNSET WITH THE POTENTIAL FOR HIGHER GUSTS. WHILE THERE COULD BE A FEW LIGHT SHOWERS OR SPRINKLES TODAY...THE BEST TIMING FOR SHOWERS AND A FEW THUNDERSTORMS WILL BE FROM LATE AFTERNOON THROUGH MID/LATE EVENING. TEN HOUR FUEL MOISTURE DIPPED TO 8-9 PERCENT ON FRIDAY AND SIMILAR VALUES ARE POSSIBLE TODAY. AS A RESULT...THERE WILL BE AN INCREASED FIRE DANGER AND WHILE MEETING RED FLAG CRITERIA IS NOT EXPECTED... CONDITIONS WILL NEED TO BE MONITORED THROUGH DAY. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * MVFR CIGS OVERNIGHT INTO SUNDAY MORNING * WIND SHIFT TO EASTERLY SUNDAY AFTERNOON IZZI //DISCUSSION...UPDATED 06Z... COLD FRONT MOVING THROUGH THE REGION AT THIS TIME WITH SHRA/TSRA MOVING EAST OF THE REGION. EXPANDING BANK OF STRATUS HAS BEEN NOTED ON SATELLITE IMAGERY UPSTREAM OVER WI/IA INTO NW IL WITH GUIDANCE SUGGESTING THIS SHOULD CONTINUE TO EXPAND EAST INTO THE TERMINALS OVERNIGHT. DOES APPEAR THAT MIXING/HEATING SHOULD HELP ERODE THE STRATUS SUNDAY MORNING...THOUGH TIMING OF SCATTERING OUT CIGS IS UNCERTAIN. WESTERLY WINDS SHOULD GUST OCCASIONALLY TO 15-20KT OVERNIGHT BEFORE EASING SUNDAY MORNING. PRESSURE FALLS OVER THE PLAINS EXPECTED TO RESULT IN AN ABRUPT SHIFT TO EASTERLY WINDS SUNDAY EVENING...WITH THE TIMING OF THAT WIND SHIFT LIKELY A BIT EARLIER AT ORD/MDW/GYY AS COLLAPSING GRADIENT IN THE AFTERNOON SHOULD ALLOW FOR ROBUST LAKE BREEZE DEVELOPMENT. NEXT DISTURBANCE LIKELY TO APPROACH THE REGION TOWARD THE END OF OR JUST BEYOND THE ORD 30 TAF HOUR PERIOD WITH ADDITIONAL SHRA/TSRA EXPECTED AT THAT TIME. IZZI //ORD AND MDW CONFIDENCE...UPDATED 06Z... * MEDIUM-HIGH CONFIDENCE IN LOW END MVFR CIGS OVERNIGHT INTO SUN AM * LOW-MEDIUM CONFIDENCE ON TIMING OF IMPROVEMENT TO VFR SUNDAY MORNING * HIGH CONFIDENCE ON WIND SHIFT TO EAST SUN PM IZZI //OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z... MONDAY...SHRA/TSRA LIKELY EARLY. MVFR/BRIEF IFR POSSIBLE EARLY. TUESDAY THROUGH THURSDAY NIGHT...PERIODIC CHANCE FOR SHRA/TSRA. PERIODIC MVFR CIGS/VSBY LIKELY WITH BRIEF IFR POSSIBLE. FRIDAY...PROBABLE VFR. MDB && .MARINE... 241 PM CDT LOW PRESSURE OVER SOUTHERN MINNESOTA THIS AFTERNOON IS LIFTING A STRONG WARM FRONT ACROSS LAKE MICHIGAN TODAY. WINDS OVER THE LAND ARE TOPPING OUT AROUND 35 KT THIS AFTERNOON WITH THESE GALES EXTENDING INTO THE NEARSHORE WATERS WHERE A GALE WARNING REMAINS IN EFFECT THROUGH THIS EVENING. HOWEVER...WITH TEMPERATURES PUSHING 70 ACROSS NORTHERN ILLINOIS/INDIANA...VERY STABLE CONDITIONS ARE SETTING UP OVER THE OPEN WATERS OF THE LAKE AND SHOULD BE INHIBITING THE STRONGER GUSTS FROM REACHING THE LAKE SURFACE. THE LOW WILL MOVE ACROSS NORTHERN LAKE MICHIGAN LATE THIS EVENING WITH A TRAILING COLD FRONT PUSHING ACROSS THE LAKE SHORTLY THEREAFTER WITH WINDS TURNING WESTERLY AND DIMINISHING. ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO MOVE INTO THE REGION MIDWEEK...THOUGH MODELS CONTINUE TO STRUGGLE WITH TRACK AND TIMING MAKING IT DIFFICULT TO PIN DOWN DETAILS REGARDING OVER THE LAKE. CONTINUE TO FAVOR A FARTHER SOUTH SOLUTION SUPPORTED BY THE CONSISTENT ECMWF...WHICH THE LATEST GFS HAS TRENDED TOWARDS. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 AM SUNDAY. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1154 PM CDT SAT APR 6 2013 .DISCUSSION... ISSUED 900 PM CDT SAT APR 6 2013 A LINE OF SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE TO PROGRESS EASTWARD ACROSS THE NORTHERN HALF OF THE CWA THIS EVENING AHEAD OF A COLD FRONT. THE WINDOW OF OPPORTUNITY FOR THUNDER LOOKS TO BE AROUND 2 HOURS WITH THUNDER JUST REPORTED IN PIA AHEAD OF THE STRONGER LINE BACK NEAR GALESBURG. THE LOW LEVEL CONVERGENCE AND INSTABILITY LOOKS TO BE GRADUALLY WEAKENING AFTER SUNSET...AND THE FRONTAL CIRCULATIONS ARE FORECAST TO NEARLY DISSIPATE BY 12Z WHEN THE FRONT REACHES OUR SOUTHEAST COUNTIES. WE MAINLY KEPT THE HIGH CHANCE POPS ACROSS THE NORTH...AND PROGRESSED THEM TOWARD CHAMPAIGN BY 06Z/1AM WITH ONLY SLIGHT CHANCE POPS IN THE SOUTHEAST THIRD OF OUR COUNTIES AFTER 06Z/1AM. THE GUSTY WINDS ARE MAINLY CONFINED TO AREAS EAST OF LINCOLN TO BLOOMINGTON AT 9 PM. LIGHTER WINDS WILL ARRIVE WITH THE COLD FRONT AND A WIND SHIFT TO THE WEST. THE FRONT IS STILL EXPECTED TO RETURN NORTH AND BECOME ACTIVE AGAIN SUNDAY AFTERNOON AND ESPECIALLY SUNDAY NIGHT IN THE WEST. FOR TONIGHT...UPDATED THE POP/WEATHER AND WINDS TO MORE CLOSELY MATCH CURRENT TRENDS. NO MAJOR CHANCES OVERALL. UPDATED INFO WILL BE AVAILABLE SHORTLY. SHIMON && .AVIATION... ISSUED 1154 PM CDT SAT APR 6 2013...FOR THE 06Z TAFS SOME SHOWERS MAY AFFECT CMI FOR THE FIRST HALF HOUR OF THE TAF PERIOD...OTHERWISE THE TERMINAL SITES SHOULD REMAIN DRY OVER THE NEXT 24 HOURS. THE COLD FRONT WILL PASS ACROSS DEC/CMI OVER THE NEXT HOUR OR TWO...SO WINDS SHOULD DIMINISH FROM STRONG SOUTH TO LIGHTER SOUTHWEST AROUND 12-14KT. LATER TONIGHT ALL TAF SITES SHOULD SEE WEST WINDS AROUND 10KT. SOME MVFR CLOUDS ARE EXPECTED TO APPROACH OUR NORTHERN COUNTIES...WITH PIA AND BMI POSSIBLY SEEING SOME OF THAT. LIGHT FOG MAY EVEN AFFECT PIA AND BMI. I ADDED A TEMPO FOR BKN015 FOR 12Z TO 15Z TO MATCH THE HRRR OUTPUT FOR THAT TIME FRAME. SHIMON && .PREV DISCUSSION... ISSUED 300 PM CDT SAT APR 6 2013 00Z MODELS CONTINUE A MILD AND UNSETTLED WEATHER PATTERN THROUGH MID WEEK WITH COOLER AND DRIER CONDITIONS THE END OF NEXT WEEK. WILL USE A MODEL BLEND THIS FORECAST PACKAGE. MET AND MAV GUIDANCE TEMPS ARE SIMILAR THROUGH MON NIGHT AND STAYED FAIRLY CLOSE TO. SHORT TERM...TODAY THROUGH TUESDAY NIGHT STRONG SOUTH WINDS OF 20-35 MPH AND GUSTS OF 35-50 MPH THIS AFTERNOON WITH STRONGEST WIND GUSTS FROM I-72 NORTH. A SPECIAL WEATHER STATEMENT WAS ISSUED TO ADDRESS THESE HIGH WINDS THROUGH 8 PM. 999 MB LOW PRESSURE OVER SOUTHCENTRAL MN HAS A COLD FRONT INTO CENTRAL IA...NW MO AND CENTRAL OK. WARM FRONT HAD LIFTED NE OF IL WITH MILD TEMPS IN THE UPPER 60S AND LOWER 70S OVER CENTRAL AND SE IL AND MILDEST TEMPS SINCE NOV 10TH. LOW PRESSURE TO MOVE TOWARD NORTHERN LAKE MI BY 06Z TONIGHT AND PULL COLD FRONT TOWARD I-55. LOW PRESSURE DEEPENS TO 996 MB JUST EAST OF UPPER MI BY 12Z/SUN AND COLD FRONT SWEEPS THROUGH SE IL LATE TONIGHT INTO MID MORNING SUNDAY. HAVE CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS OVER CENTRAL IL THIS EVENING AND SHIFTING INTO SE IL OVERNIGHT INTO MID MORNING SUNDAY. LIMITED MOISTURE WITH COLD FRONT AND MODELS HAVE TRENDED LOWER WITH QPF AMOUNTS TONIGHT INTO SUNDAY. LOWS TONIGHT RANGE FROM THE LOWER 40S NW OF THE IL RIVER TO THE LOWER 50S IN SE IL. FRONTAL BOUNDARY TO START LIFTING BACK NORTH TOWARD CENTRAL/SE IL BY SUNSET SUNDAY AND RETURNING 20-40% CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS LATE SUNDAY AFTERNOON INTO PARTS OF CENTRAL AND SW IL. HIGHS TO RANGE FROM THE MID 60S NORTH OF PEORIA TO THE LOWER 70S SOUTH OF I-72. WARM FRONT LIFTS NORTH THROUGH CENTRAL IL SUNDAY NIGHT AND INTO NORTHERN IL MON AND LIKELY ACCOMPANIED BY A SHOWERS AND A CHANCE OF THUNDERSTORMS ESPECIALLY NORTH OF I-70. MILD HIGHS MON AGAIN IN THE UPPER 60S AND LOWER 70S WITH COOLEST READINGS FROM I-74 NORTH. CHANCES OF SHOWERS AND THUNDERSTORMS LINGERS TUE AND HIGHEST POPS IN NORTHERN AREAS CLOSER TO FRONTAL BOUNDARY LINGERING OVER NORTHERN IL. LONG TERM...WEDNESDAY THROUGH SATURDAY STRONG LOW PRESSURE TO EJECT NE AROUND WED WITH BEST CHANCES OF SHOWERS AND THUNDERSTORMS AND SPC HAS RISK OF STRONG TO SEVERE STORMS OVER SOUTHERN IL WED. GFS IS QUICKER WITH THIS STORM SYSTEM THAN THE ECMWF MODEL AND USED A BLEND FOR NOW WITH PLENTY OF TIME TO SORT OUT THE TIMING DIFFERENCES. MAY BE A GRADIENT OF TEMPS WED WITH COOLER HIGHS IN THE UPPER 50S NW OF THE IL RIVER AND MILDER LOWER 70S SE OF I-70. STRONG UPPER LEVEL TROF OVER THE MIDWEST THU TO KEEP LOW CLOUDS AROUND ALONG WITH LINGERING CHANCES OF SHOWERS AND COOLER TEMPS. DRIER WEATHER EXPECTED FRIDAY ALONG WITH TEMPS BEING A BIT COOLER THAN NORMAL THU/FRI WITH HIGHS IN THE 50S. 07 && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
447 AM CDT SUN APR 7 2013 .SHORT TERM...(TODAY) ISSUED AT 442 AM CDT SUN APR 7 2013 TODAY...DEEPER MOISTURE ALONG EXTENDING FROM SOUTHERN OK AND EAST TX WILL BE ADVECTED NORTHWARD AS A LEE SURFACE TROUGH DEEPENS ACROSS THE CENTRAL AND WESTERN HIGH PLAINS. THE SOUTHERLY LOW-LEVEL FLOW WILL ADVECT THIS DEEPER MOISTURE NORTHWARD ACROSS EASTERN KS LATE THIS AFTERNOON. THE WESTERN GULF OF MEXICO IS NOT AT EQUILIBRIUM EARLY THIS MORNING...BUT THE RESIDUAL MOISTURE RETURN SHOULD BE SUFFICIENT TO ALLOW MID TO UPPER 50 DEWPOINTS TO ADVECT NORTHWARD ACROSS THE CWA BY LATER AFTERNOON. MEANWHILE...A SHORTWAVE LENGTH H5 TROUGH WAS MOVING EASTWARD ACROSS CENTRAL CO...SOUTHWARD INTO NORTHWEST NM. THE NAM...ECMWF AND GFS SHOW THIS H5 TROUGH MOVING EAST ACROSS WESTERN AND CENTRAL KS TODAY. STRONGER ASCENT AHEAD OF THIS H5 TROUGH AND THE STRONGER ISENTROPIC LIFT ON THE NORTH SIDE OF DEEPER MOISTURE RETURN WILL ALLOW SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS TO DEVELOP FROM SOUTH TO NORTH ACROSS THE CWA DURING THE MID AND LATE AFTERNOON HOURS. THE VERTICAL WINDSHEAR LOOKS TO BE STRONG WITH 0-6KM SHEAR OF 40 TO 60 KTS ACROSS THE CWA THROUGH THE LATE AFTERNOON HOURS. INSTABILITY WILL INCREASE THROUGH THE AFTERNOON AS THE DEEPER MOISTURE ADVECTS NORTHWARD TO AT LEAST I-70. GIVEN STEEP LAPSE RATES FROM 700MB TO THE SURFACE...ONCE THE DEEPER MOISTURE ADVECT FAR ENOUGH NORTH WE SHOULD SEE SBCAPE INCREASE TO 1,000 TO 1,500 J/KG FROM I-70 SOUTH. THE NAM MODEL EVEN SHOWS AN ENHANCED BAND OF 0-1KM SRH OF 80-100 J/KG ALONG THE I-35 CORRIDOR BY 21Z AND LIFTING NORTHWARD TO I-70 BY 00Z. THIS WOULD BE SUFFICIENT FOR DISCRETE SUPERCELL TO POTENTIALLY PRODUCE ISOLATED TORNADOES. HOWEVER...THE MODE OF CONVECTION IS STILL IN QUESTION. THE ECMWF...GFS...AND NAM ALL SHOW NUMEROUS THUNDERSTORMS DEVELOPING ALONG I-35 AFTER 21Z AND EXTENDING WESTWARD TOWARDS ICT. IF A COMPLEX OR CLUSTER OF THUNDERSTORMS DEVELOPS LATE IN THE AFTERNOON HOURS ALONG THE NORTHERN EDGE OF DEEPER MOISTURE RETURN...THEN THE PRIMARY THREAT WILL LARGE HAIL AND SEVERE WIND GUSTS. THIS COMPLEX OF STORMS WILL DEVELOP NORTHWARD ACROSS EAST CENTRAL KS LATE IN THE AFTERNOON. IF THE THUNDERSTORMS REMAIN DISCRETE...THEN GIVEN THE 0-1KM SRH AND INSTABILITY...THEN ISOLATED TORNADOES COULD NOT BE RULED OUT FOR PORTIONS OF THE CWA...SOUTH OF I-70. THE RAP AND (ARW) WRF...TWO OF OUR MESOSCALE MODELS...SHOW THE INITIATION OF DEEP MOIST CONVECTION WEST AND SOUTHWEST OF THE CWA THROUGH THE LATE AFTERNOON HOURS. THE INITIAL MODE LOOKS DISCRETE WITH STORM MERGERS OCCURING AS THEY MOVE NORTHEAST ACROSS THE CWA DURING THE EARLY EVENING HOURS. STAY TUNED TO LATER UPDATES ON THE POTENTIAL FOR SEVERE WEATHER LATE THIS AFTERNOON AND EVENING. TEMPERATURES WILL WARM INTO THE LOWER TO MID 70S WITH PATCHES OF DENSE HIGH CLOUD COVER SPREADING ACROSS THE CWA THIS MORNING. CU SHOULD BEGIN TO DEVELOP AS THE DEEPER MOISTURE SURGES NORTHWARD THIS AFTERNOON. GARGAN .LONG TERM...(TONIGHT THROUGH SATURDAY) ISSUED AT 442 AM CDT SUN APR 7 2013 CONVECTIVE COMPLEX OF SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP/EXPAND EAST AND NORTHEAST ACROSS PRIMARILY THE SOUTHEAST HALF OF THE CWA THROUGH THE EARLY AND MID EVENING HOURS WITH A THREAT FOR PRIMARILY LARGE HAIL WITH THE STRONGER STORMS. HOWEVER...AS THE SHORTWAVE TROUGH MOVES THROUGH BY LATE EVENING...THE LLVL FLOW WILL BEGIN TO VEER AND ALLOW FOR SOME DRIER AIR TO ADVECT EASTWARD WHICH WILL FAVOR THE MORE EASTWARD PROGRESSION OF THE POSSIBLE MCS. HAVE THEREFORE TRENDED THE HIGHER POPS THROUGH THE EARLY/MID EVENING...THEN A GRADUAL DECREASED POP THROUGH LATE EVENING/MIDNIGHT...THEN A MUCH MORE RAPID DROP IN POPS AFTER MIDNIGHT WEST TO EAST ACROSS THE CWA. WILL KEEP THE SOUTHEAST CWA WARMER WITH THE CLOUDS AND HIGHER DEWPOINTS IN THE UPPER 50S WITH NEAR 50 IN THE FAR NORTH CENTRAL. ON MONDAY...OVERALL LACK OF LARGE SCALE ASCENT/FORCING WITHIN AN ENVIRONMENT EXHIBITING A RAPIDLY STRENGTHENING ELEVATED MIXED LAYER (EML) DOES NOT INCREASE CONFIDENCE IN CARRYING POPS BEYOND LOW END CHANCE CATEGORY. HAVE REMOVED POPS FOR MOST OF THE MORNING...BUT CARRIED LOW POPS IN THE LATE MORNING/AFTERNOON...ALTHOUGH IMPRESSIVE INHIBITION MAY WARRANT LOWERING/OR REMOVING POPS MORE. KEPT HIGHS IN THE LOW TO MID 70S DUE TO EXPECTED STRATUS DECK BENEATH INVERSION. BY MONDAY NIGHT...MORE CONVECTION IS EXPECTED TO ADVANCE/DEVELOP EASTWARD FROM WESTERN/CENTRAL KANSAS THROUGH THE NIGHT PRIMARILY ALONG THE NORTH OF THE WARM FRONT AS LLVL JET INCREASES THROUGH THE NIGHT. THE FOCUS FOR THIS HAS CONTINUES TO TREND NORTHWARD WITH TIME AND STRONG CAPPING OVER THE CWA MAY ALSO INHIBIT THE SOUTH AND EASTWARD EXTENT OF THE CONVECTION AS WELL. FOR NOW...HAVE KEPT LIKELY POPS ACROSS THE NORTHERN 2/3 OF THE CWA...BUT IF MODEL TRENDS CONTINUE...THE HIGHER POPS MAY NEED TO BE TRIMMED/SHIFTED MORE NORTHWARD CLOSER TO THE NE BORDER. TUESDAY AND TUESDAY NIGHT STILL APPEARS TO BE THE MOST ACTIVE TIMEFRAME FOR THIS STORM SYSTEM ACROSS OUR CWA AS A DEEPENING SFC LOW/COLD FRONT ADVANCES EASTWARD ACROSS THE AREA AS THE MAIN SHORTWAVE ROTATES NORTHEAST OUT OF THE LONGER WAVE TROUGH IN THE WEST INTO THE NORTHERN PLAINS EARLY WEDNESDAY. CONVECTION COULD FIRST INITIATE OVER CENTRAL KS THEN CONGEAL INTO A POSSIBLE SQUALL LINE AS IT MOVES EAST THROUGH THE AFTERNOON/EVENING WITH ALL MODES OF SEVERE WEATHER POSSIBLE DURING THIS TIME FRAME BEFORE THE FRONT USHERS IN COOLER AND DRIER AIR INTO EASTERN KS LATE IN THE NIGHT. WILL KEEP A LINGERING CHANCE FOR DECREASING CONVECTION/RAIN POTENTIAL ON WEDNESDAY WITH SHOWERS EXITING THE CWA WEDNESDAY NIGHT...THEN DRY THURSDAY INTO FRIDAY NIGHT. A SLIGHT CHANCE FOR SHOWERS WILL RETURN BY SATURDAY. AFTER HIGHS IN THE 60S/70S ON TUESDAY...WEDNESDAY TEMPS WILL COOL INTO THE 40S AND 50S FOR WEDNESDAY AND THURSDAY...THEN THE 50S FRIDAY AND THE 60S FOR SATURDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1212 AM CDT SUN APR 7 2013 FOR THE 06Z TAFS...WINDS HAVE BECOME LIGHT AND VARIABLE ACROSS THE AREA THIS EVENING AND WILL REMAIN LIGHT THROUGH AROUND SUNRISE. WINDS ARE EXPECTED TO INCREASE OUT OF THE SOUTH-SOUTHEAST LATER THIS MORNING WITH INCREASING MID-LEVEL CLOUDS THROUGH THE DAY AS A LOW PRESSURE SYSTEM APPROACHES THE AREA. COULD SEE SOME SHOWERS AND THUNDERSTORMS DEVELOP OVER THE AREA DURING THE EVENING HOURS...WHICH COULD LOWER CIGS/VIS TO MVFR CONDITIONS AND POSSIBLY LOWER. THERE IS STILL UNCERTAINTY IN THE TIMING AND SCALE OF THIS SHOWER/THUNDERSTORM ACTIVITY...SO WILL LIKELY NEED TO FINE TUNE THE TIMING WITH FUTURE TAF UPDATES. AT THIS TIME THOUGH...MOST OF THE ACTIVITY LOOKS TO BE MOVING EAST OF THE AREA BY AROUND 06Z. ACH && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GARGAN LONG TERM...63 AVIATION...HENNECKE
AREA FORECAST DISCUSSION
NWS JACKSON KY
130 AM EDT SUN APR 7 2013 .UPDATE... ISSUED AT 130 AM EDT SUN APR 7 2013 LATEST HRRR SHOWS A MUCH SLOWER PROGRESSION OF THE FRONTAL BOUNDARY TOWARDS OUR AREA TOMORROW AND PENETRATING MUCH LESS INTO THE AREA. THUS...HAVE TRIMMED BACK POPS ACROSS EAST CENTRAL KENTUCKY. A LITTLE CONCERNED EARLIER BY THE AMOUNT OF DRY AIR STILL PRESENT ACROSS EASTERN KENTUCKY WITH DEWPOINTS STILL HOLDING IN THE LOWER TO MIDDLE 30S IN MANY LOCATIONS. HAVE GONE AHEAD AND LOWERED DEWPOINTS THROUGH THE DAY TODAY...ESPECIALLY ACROSS THE SOUTHEAST. MODELS APPEAR TO BE TOO AGGRESSIVE WITH THE MOISTURE RECOVERY ONCE AGAIN. FORTUNATELY...EVEN USING A WORST CASE SCENARIO...I CANNOT GET RELATIVE HUMIDITIES TO FALL UNDER 25 PERCENT...SO THAT PUTS RED FLAG CRITERIA OUT OF THE PICTURE. HOWEVER...STILL GOING TO SEE THE POTENTIAL FOR DANGEROUS FIRE WEATHER CONDITIONS TODAY WITH MUCH GUSTIER SOUTHWEST WINDS DEVELOPING BY MID MORNING. PLAN TO HIGHLIGHT THIS FIRE DANGER IN THE FIRE WEATHER PLANNING FORECAST AND IN THE HWO. UPDATE ISSUED AT 1042 PM EDT SAT APR 6 2013 MADE A FEW ADJUSTMENTS TO THE LOW TEMPERATURES TONIGHT. THE FAR EASTERN SHELTERED VALLEYS ARE ON THEIR WAY DOWN...WITH A FEW SPOTS ALREADY DIPPING TO BELOW 50 DEGREES. AT THIS PACE...A FEW UPPER 30S STILL LOOK ACHIEVABLE. FURTHER WEST...TEMPERATURES HAVE BEEN SLOW TO COOL OFF WITH PERSISTENT HIGH CLOUDS THROUGH EARLY THIS EVENING AS WELL SOUTH TO SOUTH SOUTHEAST WINDS AT AROUND 5 KTS. THERE WILL BE A DECENT CLEAR SLOT FOR SEVERAL HOURS...SO A DROP OFF STILL LOOKS GOOD...HOWEVER DID TWEAK UP SOME OF THE LOWS IN THE WESTERN HALF OF THE AREA GIVEN THE SLOW START. UPDATE ISSUED AT 705 PM EDT SAT APR 6 2013 AN AREA OF THICKER HIGH CLOUDS IS CURRENTLY MOVING EAST ACROSS THE AREA. THE BACK EDGE OF THESE THICKER CLOUDS WILL EXIT THE FAR EAST BEFORE MIDNIGHT BASED ON THE LATEST SATELLITE TRENDS. WILL THEREFORE MENTION MOSTLY CLOUDY WORDING EARLY ON FOR SOME LOCATIONS. CONSEQUENTLY...WILL TWEAK THE DIURNAL DROP OFF...HOWEVER WILL STICK WITH THE FORECAST LOWS FOR NOW. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 302 PM EDT SAT APR 6 2013 HIGH THIN CLOUDS WILL STREAM INTO THE AREA TONIGHT...BUT THIS SHOULD NOT PREVENT ANOTHER FAIRLY SIGNIFICANT RIDGE VALLEY TEMPERATURE SPLIT SETTING UP. THIS WILL BE DEPICTED IN THE FORECAST GRIDS WITH CLOSE TO A 10 DEGREE SPREAD IN SOME AREAS...ESPECIALLY IN THE EAST. A COLD FRONT WILL DROP SOUTH INTO OHIO AND INDIANA ON SUNDAY. THE 12Z NAM AND GFS HAVE TRENDED TOWARDS THE PRECIPITATION CHANCES EXTENDING A LITTLE FURTHER SOUTH...AND THIS IS REFLECTED IN THEIR CORRESPONDING MOS GUIDANCE AS WELL. THIS IDEA IS ALSO SUPPORTED BY THE 09Z SREF BUT NOT BY THE 12Z GEM OR 00Z ECMWF. IT STILL APPEARS THERE WILL BE A FAIRLY STRONG GRADIENT OF PRECIPITATION CHANCES ON SUNDAY...AND WILL CARRY AROUND 10 PERCENT IN THE FAR SOUTHEAST TO 40 TO 50 PERCENT IN THE FAR NORTH. BEST INSTABILITY...WITH LI/S DROPPING BELOW ZERO WILL BE IN THE NORTH...AND WILL CARRY ISOLATED THUNDERSTORMS IN THE NORTH AND NORTHWEST PART OF THE FORECAST AREA. RAIN CHANCES WILL BE DECREASING SUNDAY NIGHT...BUT WILL STILL WARRANT A MENTION ACROSS THE NORTH AND WEST PART OF THE FORECAST AREA. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 302 PM EDT SAT APR 6 2013 THE MODELS ARE IN DECENT AGREEMENT WITH THE GENERAL PATTERN AS THEY TRY TO TRANSITION AN UPPER LOW NEAR FOUR CORNERS INTO THE GREAT PLAINS ON WEDNESDAY AND THEN INTO THE OHIO VALLEY AND THEN EITHER INTO THE GREAT LAKES ON FRIDAY AS WITH THE GFS OR INTO THE DAKOTAS AS FORECAST BY THE ECMWF. MANY OF THE SOLUTIONS FAVOR THE FASTER GFS...HOWEVER THEY HAVE BEEN PLAGUED BY SOME RUN TO RUN INCONSISTENCIES. THE FORECAST FAVORS THE SLOWER ECMWF FORECAST. WITH THIS TYPE OF SYNOPTIC SITUATION...THE MODELS ARE CONSISTENTLY TOO QUICK IN KICKING OUT THE LOW. CONFIDENCE THROUGH THURSDAY IS FAIRLY HIGH BUT THEN DROPS STEEPLY FOR FRIDAY AND BEYOND DUE TO THE TIMING ISSUES FROM THE FRONT. SOME SHORT WAVES WILL BE MOVING THROUGH THE UPPER LOW AND AS THEY DO THEY WILL GENERATE WAVES ON THE QUASI STATIONARY FRONT WHICH WILL SET UP JUST TO THE NORTH OF THE AREA. THE EXACT LOCATION WHERE THIS FRONT SETS UP COULD MAKE A BIG DIFFERENCE IN HOW FAR SOUTH THE FRONT SAGS. THIS WILL CONSEQUENCES AS TO THE WEATHER EXPECTED IN THE NORTHERN PORTION OF THE FORECAST AREA. THE SOUTHERN AREA SHOULD NOT REALLY BE THAT AFFECTED UNTIL THE FRONT ACTUALLY STARTS MOVING ACROSS THE AREA ON EITHER ON FRIDAY. FOR TEMPERATURES...STAYED CLOSE TO THE MODEL BLEND...HOWEVER HAD TO MAKE CHANGES TO THE LOWS DUE TO THE RIDGE VALLEY TEMPERATURE DIFFERENCES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 130 AM EDT SUN APR 7 2013 VFR CONDITIONS WILL HOLD ON THROUGH THE PERIOD. AN INCREASING LOW LEVEL JET ACROSS THE OHIO VALLEY WILL ALLOW FOR THE THREAT OF LOW LEVEL WIND SHEAR THROUGH DAWN. AN APPROACHING COLD FRONT WILL MOVE INTO SOUTHERN OHIO TODAY. SOME SCATTERED SHOWERS AND A FEW THUNDERSTORMS ARE POSSIBLE...MAINLY NORTH OF THE MOUNTAIN PARKWAY. LOWER CLOUDS AND PRECIPITATION WILL NOT LIKELY MAKE IT SOUTH OF I-64...KEEPING THE TAF SITES DRY WITH JUST SOME HIGH CLOUDS TO CONTEND WITH. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KAS SHORT TERM...SBH LONG TERM...JJ AVIATION...KAS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
415 AM EDT SUN APR 7 2013 .SYNOPSIS... WE EXPECT MILD, SPRING WEATHER TODAY, WITH A CHANCE OF SHOWERS. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... TEMPERATURE TREND THIS MORNING A BIT WARMER THAN PREVIOUS FCST, SO MADE THE SMALL ADJUSTMENT. ALSO ADJUSTED DEW POINTS WAY DOWN. HIGH TEMPS ON LOWER SIDE OF GUIDANCE. KEPT SOME GUSTY WINDS IN AS WE EXPECT SOME OF THE MODERATE WIND JUST ABOVE THE SURFACE TO MIX DOWN. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... MODEL CONSENSUS FAVORS A STALLING OF THE FRONT ACROSS NORTHERN WEST VIRGINIA SUNDAY NIGHT BEFORE IT TURNS NORTHWARD AS A WARM FRONT ON MONDAY. POPS FOR SHOWERS WERE CONTINUED THROUGH MONDAY NIGHT BEFORE BEING INCREASED AGAIN ON TUESDAY. KEPT THUNDER MONDAY AFTERNOON/EVENING AS THE HIGHER CAPE SUGGESTS. WHILE AGREEMENT ON THE PLACEMENT OF THE FRONT BY TUESDAY BECOMES LESS PRONOUNCED...THE ECMWF/GFS/NAM ALL LIKE THE IDEA OF TRACKING A SHRTWV ALONG THE BNDRY BY THE AFTERNOON HOURS. THIS WOULD INCRS LIFT AND SHEAR ALONG THE FRONTAL ZONE. THESE INGREDIENTS WITH SOME WEAK INSTABILITY MAY BE SUFFICIENT TO OVERCOME A MODERATELY STRONG CAP ALONG THE BOUNDARY. THUS...A MENTION OF THUNDERSTORMS WAS ADDED. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... OVERALL...CONFIDENCE IN EXTENDED FORECAST IS LOWER THAN NORMAL...SIMILAR TO YESTERDAY. FRONT WILL STILL BE HUNG UP TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...PROBABLY TO THE NORTH OF THE REGION. ALTHOUGH COLD FRONT WILL LIKELY BEGIN TO CROSS THE REGION ON THURSDAY...GFS/ECMWF CANNOT DECIDE WHETHER THE COLD FRONT WILL TAKE 24 OR 48 HOURS TO PUSH ALL THE WAY THROUGH. HAVE BUMPED UP POPS TO LIKELY THURSDAY NIGHT...BUT OTHERWISE MADE LITTLE CHANGES TO POPS OR TEMPERATURES. && .AVIATION /08Z SUNDAY THROUGH THURSDAY/... VFR CONDITIONS WL CONTINUE THIS MRNG ALTHOUGH BROAD SWATH OF MID LVL CLDINESS CONTS TO FLOW OVR THE UPR OH VALLEY REGION. THE ONLY AVIATION CONCERN THIS MRNG WILL LOW LEVEL WIND SHEAR AS LLVL JET SURGES TWD LOW PRES CROSSING THE GREAT LAKES. THAT SYSTEM WL DRAG A WEAK FRONT ACRS AREA PORTS ON SUNDAY...GIVEN THE INITIALLY PALTRY BNDRY LAYER MSTR SUPPLY AND EXPECTED EWD PROGRESS OF THE SPPRTG SHRTWV...FORECAST WL FEATURE -SHRA WITH HIGH BASED CIGS AND VEERED WIND...GUSTS OF WHICH MAY APPRCH 30 KT SHOULD NAM AND RAP MOMENTUM TRANSFER PROGNOSIS BE REALIZED. CONFIDENCE IN MORE SIGNIFICANT OR WIDESPREAD DETERIORATION IS NOT SUFFICIENT TO WARRANT TAF MENTION JUST YET. .OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/... THE BOUNDARY SHOULD SHIFT SOUTH OF THE REGION TONIGHT...THEN BE PULLED NORTHWARD ONCE AGAIN ON MONDAY AS LOW PRES DIGS ACRS THE GREAT LAKES. FRONT POSITIONING IS QUESTIONABLE THROUGH MUCH OF THE WEEK...SO OCCASIONAL RESTRICTIONS SHOULD BE ANTICIPATED. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
137 AM EDT SUN APR 7 2013 .SYNOPSIS... RAIN CHANCES WILL INCREASE TODAY AS A COLD FRONT SLIDES OVER THE REGION. && .NEAR TERM /THROUGH TODAY/... TEMPERATURE TREND OVERNIGHT A BIT WARMER THAN PREVIOUS FCST, SO MADE THE SMALL ADJUSTMENT. MOISTURE IS LIMITED AND THUNDER AHEAD OF FRONT ALMOST GONE, SO WE REMOVED MENTION OF IT TODAY. HIGH TEMPS ON LOWER SIDE OF GUIDANCE. ALSO UPPED WINDS AND ATTENDING GUSTS BECAUSE OF LOW DEW POINTS AT SURFACE AND MODERATE WINDS JUST ABOVE. && .SHORT TERM /TONIGHT THROUGH TUESDAY/... MODEL CONSENSUS FAVORS A STALLING OF THE FRONT ACROSS NORTHERN WEST VIRGINIA SUNDAY NIGHT BEFORE IT TURNS NORTHWARD AS A WARM FRONT ON MONDAY. POPS FOR SHOWERS WERE CONTINUED THROUGH MONDAY NIGHT BEFORE BEING INCREASED AGAIN ON TUESDAY. WE ADDED THUNDER TO MONDAY AFTERNOON/EVENING AS THE HIGHER CAPE SUGGESTS. WHILE AGREEMENT ON THE PLACEMENT OF THE FRONT BY TUESDAY BECOMES LESS PRONOUNCED...THE ECMWF/GFS/NAM ALL LIKE THE IDEA OF TRACKING A SHRTWV ALONG THE BNDRY BY THE AFTERNOON HOURS. THIS WOULD INCRS LIFT AND SHEAR ALONG THE FRONTAL ZONE. THESE INGREDIENTS WITH SOME WEAK INSTABILITY MAY BE SUFFICIENT TO OVERCOME A MODERATELY STRONG CAP ALONG THE BOUNDARY. THUS...A MENTION OF THUNDERSTORMS WAS ADDED. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... OVERALL...CONFIDENCE IN EXTENDED FORECAST IS LOWER THAN NORMAL...SIMILAR TO YESTERDAY. FRONT WILL STILL BE HUNG UP TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...PROBABLY TO THE NORTH OF THE REGION. ALTHOUGH COLD FRONT WILL LIKELY BEGIN TO CROSS THE REGION ON THURSDAY...GFS/ECMWF CANNOT DECIDE WHETHER THE COLD FRONT WILL TAKE 24 OR 48 HOURS TO PUSH ALL THE WAY THROUGH. HAVE BUMPED UP POPS TO LIKELY THURSDAY NIGHT...BUT OTHERWISE MADE LITTLE CHANGES TO POPS OR TEMPERATURES. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... VFR CONDITIONS WL CONTINUE THIS MRNG ALTHOUGH BROAD SWATH OF MID LVL CLDINESS CONTS TO FLOW OVR THE UPR OH VALLEY REGION. THE ONLY AVIATION CONCERN THIS MRNG WILL LOW LEVEL WIND SHEAR AS LLVL JET SURGES TWD LOW PRES CROSSING THE GREAT LAKES. THAT SYSTEM WL DRAG A WEAK FRONT ACRS AREA PORTS ON SUNDAY...GIVEN THE INITIALLY PALTRY BNDRY LAYER MSTR SUPPLY AND EXPECTED EWD PROGRESS OF THE SPPRTG SHRTWV...FORECAST WL FEATURE -SHRA WITH HIGH BASED CIGS AND VEERED WIND...GUSTS OF WHICH MAY APPRCH 30 KT SHOULD NAM AND RAP MOMENTUM TRANSFER PROGNOSIS BE REALIZED. CONFIDENCE IN MORE SIGNIFICANT OR WIDESPREAD DETERIORATION IS NOT SUFFICIENT TO WARRANT TAF MENTION JUST YET. .OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/... THE BOUNDARY SHOULD SHIFT SOUTH OF THE REGION TONIGHT...THEN BE PULLED NORTHWARD ONCE AGAIN ON MONDAY AS LOW PRES DIGS ACRS THE GREAT LAKES. FRONT POSITIONING IS QUESTIONABLE THROUGH MUCH OF THE WEEK...SO OCCASIONAL RESTRICTIONS SHOULD BE ANTICIPATED. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
436 AM EDT SUN APR 7 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 507 PM EDT SAT APR 6 2013 FIGURING OUT THIS MESSY SPRING SYSTEM CONTINUES TO BE A DIFFICULT PROPOSITION. 999MB SFC LOW CONTINUES TO TRACK EAST ACROSS MINNESOTA...JUST TO SOUTH OF TWIN CITIES AS OF 19Z. SFC WARM FRONT WELL TO SOUTH ACROSS SOUTHERN WI. TEMP OF 60F AT MSN. READINGS NEAR 40F ARE CLOSING IN ON WI BORDER. REMAINS IN THE LOW-MID 30S ELSEWHERE...COLDEST OVR THE KEWEENAW PENINSULA AND OUT IN THE FAR EASTERN CWA AROUND KERY. LARGER SCALE QUITE THE MESS AS THERE ARE MULTIPLE SHORTWAVES AND MORE OF A SPLIT TROUGH LOOK AT H7-H5. NORTHERN STREAM WAVE IS STRONGER THAN EXPECTED AND THIS HAS ALLOWED FOR STRONGER H925-H85 TROUGH TO DRAW WARM AIR AT 975-850MB INTO UPR MICHIGAN. CURRENT RADAR SHOWS INITIAL WARM AIR ADVECTION SNOW IS 1-2 HRS FROM ENDING AT KERY AND THERE HAS BEEN A DECENT LULL THAT OCCURED THIS AFTN OVR MUCH OF THE CWA...EXCEPT ACROSS THE KEWEENAW WHERE SNOW HAS BEEN STEADY MOST OF THE DAY. UPSTREAM THOSE MULTIPLE SHORTWAVE TROUGHS ARE RESULTING IN MANY AREAS OF PRECIPITATION. STRONGEST AREA OF PRECIP IS TIED TO NORTHERN WAVE...WITH WIDESPREAD PRECIPITATION OVER NORTHEAST MINNESOTA. CLUSTERS OF PRECIP ARE ALSO FILLING IN AHEAD OF SOUTHERN STREAM WAVE AND SFC LOW OVER ECNTRL MN AND ALONG SFC WARM FRONT OVER SOUTHERN WI. GRADUALLY THESE TWO SHORTWAVE TROUGHS ARE SHOWN TO PHASE OVER WI/LK MICHIGAN TONIGHT...ALLOWING PRECIPITATION TO EXPAND OVR MUCH OF CWA. FOLLOWING 975-950MB TEMPS FROM RUC/NAM/GFS POINTS TO RAIN BEING DOMINANT PTYPE EARLY THIS EVENING OVER ALL BUT KEWEENAW PENINSULA. HEAVIER PRECIPITATION MOVING OVER KDLH IN LAST HOUR HAS PRODUCED RA/FZRA/PL/SN...EVEN AS RUC WARM LAYER WAS WELL ABOVE 0C. THIS IS CERTAINLY THE DYNAMIC COOLING THAT MODELS WERE HINTING AT ON FRIDAY. HINTS FROM NAM/GFS AND HRRR...WHICH IS HANDLING CURRENT PRECIP TRENDS QUITE WELL...THAT SIMILAR SITUATION MAY OCCUR MID-LATE EVENING OVER WESTERN THIRD OF CWA. TRIED TO SHOW THIS IN PYTPE GRIDS AND ALSO INCREASED SNOWFALL AMOUNTS INTO 2-4 INCH RANGE FROM IRONWOOD TO HOUGHTON AND INTO THE HURON MOUNTANS. ELSEWHERE THOUGH LATE EVENING DO NOT EXPECT MUCH SNOW AT ALL AS WARM AIR ALOFT DOMINATES. LATE EVENING INTO THE EARLY OVERNIGHT CHANGEOVER FROM RAIN TO SNOW OCCURS INTO THE CNTRL AND EASTERN CWA. A COUPLE INCHES OF SNOW MAY OCCUR WITH THE CHANGE BUT DEFORMATION HINTS FROM THE MODEL QPF FIELDS NOT AS STRIKING/PERSISTENT. BY LATE TONIGHT...ALL PRECIP WILL BE IN THE FORM OF SNOW...BUT PRECIP INTENSITY WILL BE ON THE WANE AS COMMA HEAD OF LOW PRESSURE DIMINISHES. IMPROVING WEATHER ON SUNDAY WITH LINGERING CLOUDS GIVING WAY TO AFTERNOON SUNSHINE. ONSHORE FLOW OFF LK SUPERIOR SHOULD KEEP TEMPS ON THE COOL SIDE OVER THE NORTH HALF. READINGS INTO THE LOWER 40S SEEM REASONABLE IN THE SOUTH WITH DOWNSLOPING FLOW AND MORE SUNSHINE. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 435 AM EDT SUN APR 7 2013 MUCH MORE ACTIVE PERIOD THIS WEEK ALTHOUGH THE BELOW NORMAL TEMPERATURES WILL REMAIN OVER THE AREA. FIRST SYSTEM OF NOTE AFFECTING THE REGION ON MONDAY IS IN RESPONSE TO ENERGY EJECTING OUT OF A WESTERN CONUS TROUGH. THIS ACTUALLY LEADS TO THREE DIFFERENT AREAS OF PRECIPITATION/FORCING. THE FIRST AREA IS OVER THE LOWER GREAT LAKES AND ASSOCIATED WITH A SHORTWAVE MOVING THROUGH THAT REGION. THE SECOND AREA IS FARTHER TO THE WEST ACROSS THE UPPER MISSISSIPPI VALLEY AND NORTHERN PLAINS...ASSOCIATED WITH THE TIGHTENING THERMAL GRADIENT BETWEEN THE LOW IN EASTERN COLORADO AND A HIGH IN ALBERTA. THE THIRD AREA...THAT IS EXPECTED TO AFFECT OUR AREA IS DUE TO AN INVERTED TROUGH FROM THE LOW IN COLORADO AND A WEAKER SHORTWAVE MOVING THROUGH THE WSW FLOW ALOFT. THIS TROUGH WILL SLOWLY SHIFT EAST ACROSS THE CWA ON MONDAY AND WITH THE AREA UNDER A COUPLED JET AND BROAD SOUTHERLY WAA...WOULD EXPECT LIGHT TO MODERATE PRECIPITATION TO OCCUR ACROSS THE AREA. THERMAL FIELD LOOKS TO SETUP SIMILAR LOCATION WISE TO THE SYSTEM THAT AFFECT THE AREA THIS PAST EVENING. ALL MODELS ARE SHOWING A STRONG NOSE OF WARM AIR...FROM 0C OVER THE KEWEENAW TO 4-5C AT KMNM...AT 850MB. THIS WOULD LEAD TO LIMITED TO NO MELTING OVER THE KEWEENAW AND COMPLETE MELTING OVER THE SOUTH CENTRAL. PRECIPITATION TYPE THEN COMES DOWN TO LOW LEVEL AND SURFACE TEMPS. AT THIS POINT...LOOKS LIKE INITIAL SNOW OVER THE KEWEENAW BEFORE RAIN/SNOW IN THE AFTERNOON...AN INITIAL PERIOD OF RAIN/SNOW/FZRA OVER THE REST OF THE WEST/CENTRAL BEFORE GOING TO RAIN AND THEN MAINLY RAIN EAST WITH THE WARMER AIR COMING OFF LAKE MICHIGAN WITH THE SOUTHEAST FLOW...WETBULB VALUES STAYING ABOVE FREEZING...AND THE LATER ARRIVAL OF PRECIPITATION DURING THE DAY. 21Z SREF PROBABILITIES HAD A SIMILAR IDEA AND HAVE FOLLOWED A COMBINED THICKNESS AND SREF PROBS FOR P-TYPE. DECENT VARIABILITY IN QPF AMOUNTS FROM THE MODELS...ALTHOUGH THE TREND HAS BEEN TOWARDS HIGHER AMOUNTS. GFS/NAM SHOWING A SWATH OF 1 INCH QPF OVER A PORTION OF THE WESTERN CWA IN AN AREA THAT HAS HAD A SIMILAR SIGNAL OVER THE LAST SEVERAL RUNS WITH THE FOCUS OF THE 925-850MB WAA...SO WILL CONTINUE TO FOCUS ON THE CORRIDOR BETWEEN KIWD/KCMX TO THE WEST AND KIMT/KP53 TO THE EAST FOR THE HIGHEST POPS/QPF. ON A POSITIVE NOTE...THAT AREA IS ONE OF THE LONGER TERM DRIER AREAS OF THE CWA...ESPECIALLY IN THE MICHIGAMME RIVER BASIN...SO ADDITIONAL PRECIPITATION WILL BE GOOD FOR HYDROLOGIC USES BUT NOT AS MUCH FOR SPRING SNOWMELT POTENTIAL. WITH THE REGIONAL GEM ALSO SHOWING HEAVIER PRECIP DURING THAT TIME...WILL MAKE A SIGNIFICANT JUMP TO THE QPF VALUES /MORE THAN DOUBLE IN SOME AREAS/ ALTHOUGH NOT AS HIGH AS SOME OF THE MODELS ARE SHOWING. HAVE MENTIONED A COUPLE HOUR PERIOD OF MAINLY FREEZING RAIN AROUND DAYBREAK. WITH THIS OCCURRING AROUND THE MORNING COMMUTE...COULD BE QUITE SLICK AND WILL CONTINUE TO MENTION THE FREEZING RAIN IN THE HWO. AS THE TROUGH SHIFTS TO THE EAST...EXPECT COOLER AIR TO SLIDE SOUTHEAST ACROSS THE AREA AND TRANSITION THE PRECIPITATION TO SNOW. BUT THE LOSS OF DEEP MOISTURE AND FORCING /SHORTWAVE HAS DEPARTED/...THINK ANY SNOWFALL ACCUMULATIONS WILL BE LIGHT DURING THE EVENING AND EARLY OVERNIGHT HOURS. IN ADDITION...THIS LOSS OF MOISTURE COULD LEAD IT TO BE MORE OF A DRIZZLE/FREEZING DRIZZLE SITUATION INSTEAD OF SNOW...SO ADDED THAT IN OVER THE NW HALF OF THE CWA TOWARDS THE OVERNIGHT HOURS. HIGH PRESSURE THEN SETTLES IN OVER THE UPPER GREAT LAKES FOR TUESDAY AND SHOULD LEAD TO A QUIET...BUT ONCE AGAIN BELOW NORMAL TEMPERATURES. EXPECT THERE TO BE LINGERING LOW CLOUDS IN THE MORNING OVER MUCH OF THE AREA AND THEN AS THOSE CLOUDS DIMINISH THE AREA WILL SEE INCREASING MID-HIGH CLOUDS AHEAD OF THE NEXT SHORTWAVE APPROACHING THE AREA. SO ALL IN ALL...EXPECT A MOSTLY CLOUDY DAY FOR MOST OF THE CWA. THERE IS ALSO THE POTENTIAL THAT PRECIPITATION FROM THE NEXT WAVE COULD SLIDE IN DURING THE LATE AFTERNOON HOURS AND HAVE SLIGHT CHANCES TO ACCOUNT FOR THAT. THE UNCERTAIN PORTION OF THE FORECAST THEN SETS UP FOR TUESDAY NIGHT THROUGH THE REST OF THE WORK WEEK. WITH A LARGE UPPER TROUGH SETUP OVER THE SOUTHWESTERN CONUS...THE FORECAST DEPENDS ON SEVERAL WAVES EJECTING OUT OF THE UPPER TROUGH AROUND MID WEEK AND THEN THE TROUGH ITSELF SHIFTING EAST ON THURSDAY AND THURSDAY NIGHT. SEEMS LIKE THE MODELS HAVE THE GENERAL IDEA OF THE UPPER GREAT LAKES BEING ON THE NORTHERN FRINGE OF THESE WAVES AND THEIR ASSOCIATED PRECIPITATION. THEIR DIFFERENCES LARGELY DEPEND ON THE LOCATION OF THE UPPER TROUGH SPINNING EAST OF HUDSON BAY AND THE ASSOCIATED HIGH TO THE SOUTHWEST OF THAT. THE 12Z ECMWF HAS A FARTHER SOUTH SOLUTION...WHICH KEEPS MUCH OF THE PRECIPITATION AND EXITING WAVES TO THE SOUTH...WHILE THE GEM/GFS ARE A LITTLE FARTHER NORTH. LATE ARRIVING 00Z ECMWF DID TREND A LITTLE FARTHER NORTH AND BRUSHES THE SOUTHEAST THIRD OF THE CWA WITH PRECIP. THESE DIFFERENCES LEAD TO SOME CONCERN TO THE FORECAST...AS THE 00Z RUN OF THE GFS/GEM PUTS OVER AN INCH OF QPF OVER KMNM FOR TUESDAY NIGHT INTO WEDNESDAY MORNING...WHILE THE 12Z ECMWF HAD 0.00 AND THE 00Z RUN AROUND 0.15IN. BASED OFF GFS BUFKIT SOUNDINGS...WOULD EXPECT A MIX OF SLEET/SNOW/FREEZING RAIN OVER THE SOUTH CENTRAL IF THAT SOLUTION WAS CORRECT. THE FIRST TWO WAVES WILL AFFECT THE AREA ON TUESDAY NIGHT AND THEN ON WEDNESDAY. WHILE HIGHLIGHT BOTH OF THESE WAVES WITH CHANCE POPS OVER THE FAR SOUTHEAST AND THEN SLOWLY TAPER TO SLIGHT CHANCES TO THE NORTHWEST. WILL HAVE SLIGHTLY HIGHER POPS FOR THURSDAY INTO THURSDAY NIGHT SINCE THE MAIN TROUGH WILL BE PUSHING THROUGH THE AREA...ALTHOUGH QPF AMOUNTS SHOULD BE ON THE LIGHT SIDE. 00Z MODEL RUNS HAVE COME INTO BETTER AGREEMENT FOR FRIDAY INTO SATURDAY...WITH A HIGH PRESSURE RIDGE SETTING UP OVER THE CWA. HAVE SHIFTED THE FORECAST TOWARDS A DRY SOLUTION FOR FRIDAY AND FRIDAY NIGHT...BUT DID LEAVE SOME SLIGHT CHANCES IN ON SATURDAY AS THE NEXT WAVE APPROACHES THE AREA. AS FOR PRECIPITATION TYPE FROM TUESDAY NIGHT ON...APPEARS THERE WILL BE ENOUGH COLD AIR TO KEEP PRECIPITATION MAINLY AS SNOW AND HAVE FOLLOWED THICKNESS FIELDS FOR PRECIP TYPES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 420 AM EDT SUN APR 7 2013 AN UPPER LEVEL DISTURBANCE AND ASSOCIATED SURFACE LOW OVER THE AREA HAS CAUSED A WINTRY MIX OF RAIN AND SNOW THIS EVENING...WITH ALL TAF SITES REPORTING PRECIP AND LOW CIGS AND VIS. BY THE BEGINNING OF THE TAF PERIOD...RAIN WILL HAVE CHANGED OVER TO ALL SNOW...WITH LOW VIS AND CIGS EXPECTED TO SLOWLY LIFT AS BEST MOISTURE MOVES EASTWARD /AS IS REFLECTED IN LATEST OBS FROM KIWD WHERE INTENSITY OF SNOW HAS DECREASED AND VIS HAS INCREASED...THOUGH CIGS STILL REMAIN LOW/ THROUGH SUNDAY MORNING. HAVE IFR CONDITIONS TO START OUT...THOUGH SOME FLUCTUATIONS ABOVE AND BELOW ARE STILL POSSIBLE...SLOWLY IMPROVING THROUGH THE NIGHT BEFORE -SHSN COMES TO AN END SUN MORN. HIGH PRESSURE AND VFR CONDITIONS WILL MOVE IN OVERHEAD BRIEFLY DURING THE DAY TOMORROW...BEFORE HIGH CLOUDS RETURN BY END OF TAF PERIOD AHEAD OF NEXT SYSTEM. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 507 PM EDT SAT APR 6 2013 ACROSS LAKE SUPERIOR...SE TO E WINDS OF 15-30KT WILL BACK AROUND TO THE N/NW TONIGHT IN THE WAKE OF LOW PRES PASSING JUST S OF LAKE SUPERIOR. THE STRONGEST WINDS TONIGHT THRU SUN MORNING WILL BE OVER ERN LAKE SUPERIOR. WINDS WILL THEN STEADILY DIMINISH W TO E SUN... FALLING TO AOB 15KT...AS HIGH PRES RIDGE NOSES INTO THE UPPER LAKES. AS THE RIDGE DEPARTS...E TO SE WINDS WILL INCREASE A BIT SUN NIGHT/MON...BUT SHOULD REMAIN UNDER 20KT. TUE-THU...N TO NE WINDS WILL DOMINATE AS THE UPPER LAKES WILL BE SITUATED BTWN HIGH PRES TO THE N AND A LOW PRES TROF EXTENDING FROM THE SRN PLAINS TO THE OHIO VALLEY. AT TIMES...WINDS WILL BE IN THE 15-25KT RANGE...DEPENDING ON ANY WAVES OF LOW PRES TRACKING ALONG THE TROF TO THE S. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLA LONG TERM...SRF AVIATION...JMW MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
421 AM EDT SUN APR 7 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 507 PM EDT SAT APR 6 2013 FIGURING OUT THIS MESSY SPRING SYSTEM CONTINUES TO BE A DIFFICULT PROPOSITION. 999MB SFC LOW CONTINUES TO TRACK EAST ACROSS MINNESOTA...JUST TO SOUTH OF TWIN CITIES AS OF 19Z. SFC WARM FRONT WELL TO SOUTH ACROSS SOUTHERN WI. TEMP OF 60F AT MSN. READINGS NEAR 40F ARE CLOSING IN ON WI BORDER. REMAINS IN THE LOW-MID 30S ELSEWHERE...COLDEST OVR THE KEWEENAW PENINSULA AND OUT IN THE FAR EASTERN CWA AROUND KERY. LARGER SCALE QUITE THE MESS AS THERE ARE MULTIPLE SHORTWAVES AND MORE OF A SPLIT TROUGH LOOK AT H7-H5. NORTHERN STREAM WAVE IS STRONGER THAN EXPECTED AND THIS HAS ALLOWED FOR STRONGER H925-H85 TROUGH TO DRAW WARM AIR AT 975-850MB INTO UPR MICHIGAN. CURRENT RADAR SHOWS INITIAL WARM AIR ADVECTION SNOW IS 1-2 HRS FROM ENDING AT KERY AND THERE HAS BEEN A DECENT LULL THAT OCCURED THIS AFTN OVR MUCH OF THE CWA...EXCEPT ACROSS THE KEWEENAW WHERE SNOW HAS BEEN STEADY MOST OF THE DAY. UPSTREAM THOSE MULTIPLE SHORTWAVE TROUGHS ARE RESULTING IN MANY AREAS OF PRECIPITATION. STRONGEST AREA OF PRECIP IS TIED TO NORTHERN WAVE...WITH WIDESPREAD PRECIPITATION OVER NORTHEAST MINNESOTA. CLUSTERS OF PRECIP ARE ALSO FILLING IN AHEAD OF SOUTHERN STREAM WAVE AND SFC LOW OVER ECNTRL MN AND ALONG SFC WARM FRONT OVER SOUTHERN WI. GRADUALLY THESE TWO SHORTWAVE TROUGHS ARE SHOWN TO PHASE OVER WI/LK MICHIGAN TONIGHT...ALLOWING PRECIPITATION TO EXPAND OVR MUCH OF CWA. FOLLOWING 975-950MB TEMPS FROM RUC/NAM/GFS POINTS TO RAIN BEING DOMINANT PTYPE EARLY THIS EVENING OVER ALL BUT KEWEENAW PENINSULA. HEAVIER PRECIPITATION MOVING OVER KDLH IN LAST HOUR HAS PRODUCED RA/FZRA/PL/SN...EVEN AS RUC WARM LAYER WAS WELL ABOVE 0C. THIS IS CERTAINLY THE DYNAMIC COOLING THAT MODELS WERE HINTING AT ON FRIDAY. HINTS FROM NAM/GFS AND HRRR...WHICH IS HANDLING CURRENT PRECIP TRENDS QUITE WELL...THAT SIMILAR SITUATION MAY OCCUR MID-LATE EVENING OVER WESTERN THIRD OF CWA. TRIED TO SHOW THIS IN PYTPE GRIDS AND ALSO INCREASED SNOWFALL AMOUNTS INTO 2-4 INCH RANGE FROM IRONWOOD TO HOUGHTON AND INTO THE HURON MOUNTANS. ELSEWHERE THOUGH LATE EVENING DO NOT EXPECT MUCH SNOW AT ALL AS WARM AIR ALOFT DOMINATES. LATE EVENING INTO THE EARLY OVERNIGHT CHANGEOVER FROM RAIN TO SNOW OCCURS INTO THE CNTRL AND EASTERN CWA. A COUPLE INCHES OF SNOW MAY OCCUR WITH THE CHANGE BUT DEFORMATION HINTS FROM THE MODEL QPF FIELDS NOT AS STRIKING/PERSISTENT. BY LATE TONIGHT...ALL PRECIP WILL BE IN THE FORM OF SNOW...BUT PRECIP INTENSITY WILL BE ON THE WANE AS COMMA HEAD OF LOW PRESSURE DIMINISHES. IMPROVING WEATHER ON SUNDAY WITH LINGERING CLOUDS GIVING WAY TO AFTERNOON SUNSHINE. ONSHORE FLOW OFF LK SUPERIOR SHOULD KEEP TEMPS ON THE COOL SIDE OVER THE NORTH HALF. READINGS INTO THE LOWER 40S SEEM REASONABLE IN THE SOUTH WITH DOWNSLOPING FLOW AND MORE SUNSHINE. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 507 PM EDT SAT APR 6 2013 A PATTERN CHANGE STILL APPEARS TO BE IN THE OFFING OVER THE NEXT COUPLE OF WEEKS THAT SHOULD TRANSITION THE PERSISTENT BELOW NORMAL TEMP REGIME TOWARD A NORMAL OR ABOVE NORMAL ONE. HOWEVER... CONFIDENCE IS NOT HIGH THAT ABOVE NORMAL TEMPS WILL ACTUALLY SET IN. THE AO AND NAO WHICH HAVE BEEN IN A PREVAILING NEGATIVE PHASE SINCE EARLY/MID FEB ARE STILL BOTH FORECAST TO TREND TO THE POSITIVE PHASE WHICH SHOULD TRANSLATE TO WARMING. HOWEVER...THE GFS ENSEMBLES ARE ROUGHLY SPLIT IN EITHER MAINTAINING A WEAK NEGATIVE NAO OR ONLY GOING TO A SLIGHT POSITIVE PHASE. THE FORECASTED PHASE OF THE MJO FAVORS BLO NORMAL TEMPS FOR THE UPPER LAKES THRU ABOUT MID MONTH THEN ABOVE NORMAL LATE MONTH. SO...WHILE TEMPS OVERALL WILL LIKELY FALL ON THE COLDER SIDE OF NORMAL FOR THE NEXT WEEK OR SO...THE PROSPECT FOR NORMAL OR ABOVE NORMAL TEMPS SHOULD INCREASE FOR THE LATTER PART OF APRIL. BOTH THE GFS AND ECMWF ARE SHOWING ANOTHER TROF SETTLING INTO THE WRN CONUS IN THE 7-10DAY PERIOD...SO THAT MAY BE THE HARBINGER OF THE POSSIBLE WARMER PATTERN TO FOLLOW...OR AT LEAST ONE THAT IS MORE VARIABLE RATHER THAN PERSISTENTLY BLO NORMAL. THE PATTERN WILL ALSO BE AN ACTIVE ONE ACROSS THE CONUS. AFTER TODAYS SYSTEM AFFECTING THE UPPER LAKES...TROF AMPLIFICATION WILL OCCUR OVER THE WRN CONUS OVER THE NEXT FEW DAYS WITH THE TROF THEN SLOWLY TRANSLATING ACROSS THE CONUS DURING THE WEEK. THIS WILL PROVIDE THE POTENTIAL FOR SIGNIFICANT PCPN EVENTS THRU MUCH OF THE COMING WEEK FROM THE PLAINS EWD AS THE GULF FULLY OPENS UP. FOR UPPER MI...THIS COULD MEAN ONE OR MORE UNWELCOMED RAIN EVENTS ON A MELTING SNOWPACK WHICH IS STILL DEEP IN THE LAKE EFFECT AREAS OR SIGNIFICANT SNOW COULD STILL BE ADDED. MUCH WILL DEPEND ON THE STRENGTH OF THE ERN CANADA TROF THAT IS STILL IN PLACE UNDER THE LINGERING...BUT WEAKENING NEGATIVE AO/NAO REGIME. IF THE TROF REMAINS STRONG...EPISODES OF HVY PCPN ASSOCIATED WITH THE SLOWLY PROGRESSIVE SRN STREAM TROF WILL PASS BY TO THE S...LEAVING DRIER WEATHER TO DOMINATE HERE. WITH THE CONSIDERABLE SNOWPACK STILL IN PLACE...A DRIER WEATHER REGIME WOULD BE HELPFUL BECAUSE THE LATER WE GO THRU APRIL ADDING PCPN TO THE SNOWPACK WITHOUT MUCH MELTING THE GREATER THE POTENTIAL WILL BECOME FOR A RAPID MELTDOWN AND INCREASED FLOODING. AFTER THE FIRST WRN TROF LIFTS OUT...THE PROSPECT OF ANOTHER DEVELOPING 7-10 DAYS DOWN THE ROAD IS A CONCERN AS IT WOULD FAVOR THE POTENTIAL FOR MORE FREQUENT PCPN EVENTS ON THE MELTING SNOWPACK. AFTER SIGNIFICANT INCONSISTENCIES FOR SEVERAL DAYS AMONG ALL THE MEDIUM RANGE GUIDANCE...MODELS ARE NOW ON BOARD WITH AN INITIAL SHORTWAVE EJECTING INTO THE UPPER LAKES SUN NIGHT/MON AHEAD OF THE DEVELOPING WRN TROF. WITH PRECIPITABLE WATER VALUES RISING TO 160-200 PCT OF NORMAL...A GOOD PUSH OF ISENTROPIC ASCENT PER 295K SFC...AND FGEN FORCING UNDER RIGHT ENTRANCE REGION OF UPPER JET... PCPN APPEARS LIKELY. BASED ON 850MB TEMPS/1000-850MB THICKNESS...PTYPE SHOULD TRANSITION FROM SNOW OR SNOW/FZRA/RA WHEN IT BEGINS OVERNIGHT SUN NIGHT TO MOSTLY RAIN DURING MON. THE ONLY PLACE SOME SNOW MAY STILL MIX WITH RAIN MON AFTN IS OVER THE HIGHER TERRAIN OF NW UPPER MI. MIGHT SEE A TRANSITION BACK TO SNOW OR A RAIN/SNOW MIX AS THE PCPN EXITS MON NIGHT. DURING THE MID AND LATE WEEK PERIOD...WILL LEAN FCST MORE STRONGLY TOWARD THE ECMWF WHICH HAS NOW DEVELOPED GOOD RUN-TO-RUN CONSISTENCY OVER THE LAST 5 RUNS WITH REGARD TO THE WRN TROF LIFTING OUT. THE ECWMF ALSO SEEMS TO BETTER FIT THE PATTERN OF THE LINGERING BUT WEAKENING NEGATIVE NAO WHICH HOLDS STRONGER TROFFING IN OVER SE CANADA. IT IS ALSO ENCOURAGING TO SEE THE ONCE VERY INCONSISTENT AND EXTREME GFS SHIFTING TOWARD SOMETHING MUCH MORE LIKE THE ECMWF (MANY GFS RUNS SHOWED A STRONG SURGE OF SPRING WARMTH INTO UPPER LAKES MIDWEEK AS IT TRACKED RATHER DEEP SFC LOWS THRU THE UPPER MISSISSIPPI VALLEY). THE 00Z UKMET LENDS SUPPORT TO THE ECMWF THOUGH IT DOES HAVE A STRONGER SFC LOW FARTHER N INTO NRN LWR MI THU IN RESPONSE TO THE MAIN ENERGY LIFTING NE. THE GEM HAS BECOME MORE INCONSISTENT...AND ITS 00Z/12Z RUNS APPEAR TOO FAST LIFTING TROF OUT COMPARED TO OTHER GUIDANCE. SO...WHILE CONFIDENCE IN THE RESULTING SENSIBLE WEATHER FOR THE FCST AREA IS STILL LOW...IT IS IMPROVED FROM RECENT DAYS. IN INCORPORATING MORE OF THE ECMWF INTO THE FCST...EXPECT DRY WEATHER TO PREVAIL TUE WITH SFC HIGH PRES RIDGE NOSING INTO THE UPPER LAKES FROM THE NW. ALTHOUGH TIMING THE LIFTING OUT OF THE WRN TROF AND ANY SHORTWAVES WILL CONTINUE TO BE PROBLEMATIC...WILL SHOW SOME INCREASED POTENTIAL FOR PCPN WED... MAINLY OVER THE S WHERE LOW CHC POPS WILL BE UTILIZED...BUT MORE SO THU GIVEN THAT THE LAST 5 ECMWF RUNS HAVE BEEN POINTING TOWARD THU AS THE DAY THE MAIN PIECE OF ENERGY AFFECTS THE AREA. PTYPE WOULD PROBABLY BE MAINLY SNOW. GIVEN THE OPEN GULF...THE SNOW COULD BE SIGNIFICANT...BUT THAT POTENTIAL APPEARS TO BE DIMINISHING AS THE ECMWF HAS SHOWN A TENDENCY FOR ANY SFC LOWS TO BE WEAKER AND FARTHER SE DUE TO THE STRONGER TROF AND CONFLUENCE ZONE IT HAS LINGERING OVER SE CANADA...WHICH AGAIN DOES FIT THE RECENT PATTERN AS ALLUDED TO ABOVE. THIS RESULTS IN THE BEST PUSH OF MOISTURE/WAA BEING SUPPRESSED TO THE S AND E. WILL LINGER CHC POPS INTO FRI AS MID/UPPER LEVEL TROF PASSES AND THEN SHOOT FOR A DRY SAT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 420 AM EDT SUN APR 7 2013 AN UPPER LEVEL DISTURBANCE AND ASSOCIATED SURFACE LOW OVER THE AREA HAS CAUSED A WINTRY MIX OF RAIN AND SNOW THIS EVENING...WITH ALL TAF SITES REPORTING PRECIP AND LOW CIGS AND VIS. BY THE BEGINNING OF THE TAF PERIOD...RAIN WILL HAVE CHANGED OVER TO ALL SNOW...WITH LOW VIS AND CIGS EXPECTED TO SLOWLY LIFT AS BEST MOISTURE MOVES EASTWARD /AS IS REFLECTED IN LATEST OBS FROM KIWD WHERE INTENSITY OF SNOW HAS DECREASED AND VIS HAS INCREASED...THOUGH CIGS STILL REMAIN LOW/ THROUGH SUNDAY MORNING. HAVE IFR CONDITIONS TO START OUT...THOUGH SOME FLUCTUATIONS ABOVE AND BELOW ARE STILL POSSIBLE...SLOWLY IMPROVING THROUGH THE NIGHT BEFORE -SHSN COMES TO AN END SUN MORN. HIGH PRESSURE AND VFR CONDITIONS WILL MOVE IN OVERHEAD BRIEFLY DURING THE DAY TOMORROW...BEFORE HIGH CLOUDS RETURN BY END OF TAF PERIOD AHEAD OF NEXT SYSTEM. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 507 PM EDT SAT APR 6 2013 ACROSS LAKE SUPERIOR...SE TO E WINDS OF 15-30KT WILL BACK AROUND TO THE N/NW TONIGHT IN THE WAKE OF LOW PRES PASSING JUST S OF LAKE SUPERIOR. THE STRONGEST WINDS TONIGHT THRU SUN MORNING WILL BE OVER ERN LAKE SUPERIOR. WINDS WILL THEN STEADILY DIMINISH W TO E SUN... FALLING TO AOB 15KT...AS HIGH PRES RIDGE NOSES INTO THE UPPER LAKES. AS THE RIDGE DEPARTS...E TO SE WINDS WILL INCREASE A BIT SUN NIGHT/MON...BUT SHOULD REMAIN UNDER 20KT. TUE-THU...N TO NE WINDS WILL DOMINATE AS THE UPPER LAKES WILL BE SITUATED BTWN HIGH PRES TO THE N AND A LOW PRES TROF EXTENDING FROM THE SRN PLAINS TO THE OHIO VALLEY. AT TIMES...WINDS WILL BE IN THE 15-25KT RANGE...DEPENDING ON ANY WAVES OF LOW PRES TRACKING ALONG THE TROF TO THE S. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLA LONG TERM...ROLFSON AVIATION...JMW MARINE...ROLFSON
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1139 PM CDT SAT APR 6 2013 .UPDATE... ISSUED AT 852 PM CDT SAT APR 6 2013 A WEAK COLD FRONT NOW EXTENDING FROM EASTERN IOWA SWWD THROUGH CENTRAL MO HAS BEEN THE FOCUS OF SOME SHOWERS THIS EVENING IN OUR CWA...WITH THUNDERSTORMS OVER EASTERN IOWA AND NW ILLINOIS. MODELS THIS EVENING...INCLUDING THE HRRR AND RUC...HAVE CONTINUED TO INDICATE A NARROW BAND OF SHOWERS TO PERSIST ALONG AND JUST AHEAD OF THE FRONT AS IT MOVES THROUGH OUR CWA TONIGHT. HAVE UPPED POPS ACROSS WEST CENTRAL IL THROUGH MIDNIGHT AND INCLUDED A MENTION OF THUNDER GIVEN MUCAPE VALUES BETWEEN 100-200 J/KG OVER EASTERN IOWA AND NW ILLINOIS WHICH HAVE BEEN ENOUGH TO RESULT IN A FAIRLY SOLID LINE OF THUNDERSTORMS THIS EVENING OVER THAT AREA. HOWEVER...GIVEN MUCH OF THE FORCING REMAINS ANCHORED NORTH OF THE CWA...A CONTINUED MENTION OF SOME SPOTTY SHOWERS REMAINS SUFFICIENT FOR THE REMAINDER OF THE AREA. ASIDE FROM THE AFOREMENTIONED CHANGES...THE REST OF THE FORECAST REMAINS ON TRACK THIS EVENING...WITH ONLY MINOR CHANGES NEEDED TO ACCOUNT FOR NEAR TERM TEMPERATURE TRENDS. JP && .SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT) ISSUED AT 322 PM CDT SAT APR 6 2013 THE WEAK COLD FRONT NOW EXTENDING THROUGH NW MO WILL MOVE SEWD INTO THE REGION TONIGHT AS THE ASSOCIATED SHORT WAVE TROF TRACKS ACROSS THE UPPER MS VALLEY INTO THE GREAT LAKES. MODEL CONSENSUS IS THE FRONT SHOULD BE IN THE VICINITY OF THE I-70 CORRIDOR AT 12Z SUNDAY. PRESENTLY THERE IS NOT MUCH MORE THAN MID CLOUDS AND SPINKLES OR A SPOT SHOWER AHEAD OF THE FRONT. SOME OF THE EXPLICIT GUIDANCE SUGGESTS A NARROW BROKEN LINE OF SHOWERS/THUNDERSTORMS WILL DEVELOP ALONG THE FRONT AS IT PUSHES INTO THE CWA. THIS LOOKS A BIT OVERDONE HOWEVER...AS THE FORCING IS WEAK AND OBSERVED MUCAPES ARE LESS THAN 100 J/KJ. CURRENT THINKING IS THERE MAY BE SOME SPOTTY SHOWERS WITH THE FRONT...PRIMARILY FROM EASTERN MO INTO WESTERN ILLINOIS. TEMPERTURES ON SUNDAY SHOULD BE AT LEAST COMPARABLE TO TODAY. THE EAST-WEST ORIENTED FRONT MAY OOZE A TAD FURTHER SOUTH ON SUNDAY MORNING BUT IS EXPECTED TO BECOME QUASI-STATIONARY IN THE VICINITY OF THE I-70 CORRIDOR IN THE AFTERNOON. THE PRECIPITATION THREAT SEEMS TO LARGELY BE DEPENDENT ON THE INSTABILITY WHICH LOOKS A BIT OVERDONE IN THESE INITIAL STAGES OF THE RETURN FLOW OWING TO TOO HIGH OF SURFACE DEW POINTS. THINKING AT THIS TIME IS THERE COULD BE SOME SCATTERED SHOWERS OR THUNDERSTORMS WITHIN THE BROAD FRONTAL ZONE...ESPECIALLY IN CENTRAL MO. THE PRECIPITATION CHANCES ARE EXPECTED TO RAMP UP CONSIDERABLY ON SUNDAY NIGHT ASSOCIATED WITH FORCING VIA A MIGRATORY SHORT WAVE WITHIN THE WSW FLOW ALOFT AND INTENSIFYING AND VEERING SWLY LLJ. THE MAIN FOCUS SHOULD BE ALONG AND NORTH OF I-70 WITHIN THE COOL SECTOR NORTH OF THE RETREATING BOUNDARY. GLASS .LONG TERM...(MONDAY THROUGH NEXT SATURDAY) ISSUED AT 322 PM CDT SAT APR 6 2013 FROM MONDAY INTO TUESDAY THE DETAILS IN THE FORECAST BECOME A BIT MORE DIFFICULT TO RESOLVE DUE TO MARKED DIFFERENCES IN THE POSITION AN EAST-WEST BOUNDARY THAT WILL RESIDE ACROSS EITHER NORTHERN MO OR FURTHER NORTH INTO IOWA. THE ECMWF HAS BEEN THE MOST INSISTENT WITH THE MORE SRN POSITION AND THUS MUCH WETTER...WHILE THE REMAINDER OF THE GUIDANCE SUITE KEEPS THE BOUNDARY ALONG OR NORTH OF THE IOWA/MISSOURI BORDER WITH LESSER PRECIPITATION CHANCES. ON MONDAY MORNING I THINK THAT ANY LINGERING THREAT OF SHOWERS AND THUNDERSTORMS WILL BE ALIGNED WITH THE SWLY LLJ AXIS AND BY AFTERNOON THE EML BUILDS IN STRONGLY AND RESULTS IN SUBSTANTIAL CAPPING OF THE WARM SECTOR. THE WARM SECTOR WILL CONTINUE TO MOISTEN AND DESTABILIZE INTO TUESDAY AND SHOULD REMAIN CAPPED TO SURFACE BASED STORMS SOUTH OF THE FRONT. AT THIS TIME I HAVE KEPT MY HIGHEST POPS IN THE MONDAY-TUESDAY TIME FRAME ACROSS NRN MO INTO WEST CENTRAL ILLINOIS WHERE THE FRONT MAY EXIST...WITH POPS TAPPERED SOUTHWARD. DEPENDING ON WHERE THE FRONT EVENTUALLY RESIDES I COULD BE UNDERDONE OR OVERDONE WITH THE PRECIPITATION THREAT. THE MAIN SHOW WITH THE DEEP PROGRESSIVE LONGWAVE TROF AND ASSOCIATED SURFACE FRONT ALSO REMAINS PROBLEMATIC WITH TIMING DIFFERENCES IN THE EASTWARD PROGRESSION AMONGST THE SLOWEST ECMWF...AND FASTER GFS...GEFS AND CANADIAN. ONE PLAUSIBLE SCENARIO IS THAT THE PLAINS SEVERE WEATHER EVENT ON TUESDAY WILL GROW UPSCALE INTO A LINE/QLCS AND SHIFT EASTWARD INTO THE AREA OVERNIGHT TUESDAY INTO WEDNESDAY MORNING. ANOTHER IS THAT THIS LINE MAY REACH INTO WESTERN MO IN A WEAKENING STATE LATE TUESDAY NIGHT AND THE MAIN EVENT MAYBE WED AFTERNOON AND EVENING IN THE CWA PER THE ECMWF. THUS SOMEWHERE IN THE LATE TUESDAY NIGHT- WEDNESDAY NIGHT TIME FRAME WE ARE LIKELY TO SEE SIGNIFICANT CONVECTION...SOME OF WHICH COULD BE SEVERE. A COOL DOWN IS FORECAST IN THE WAKE OF THE FRONT THURSDAY INTO FRIDAY WITH BROAD CYCLONIC FLOW ALOFT. GLASS && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1139 PM CDT SAT APR 6 2013 WEAK COLD FRONT IS SLIDING THROUGH REGION AND HAS MOVED THROUGH KUIN AND KCOU...AND SHOULD BE MOVING THROUGH METRO AREA BETWEEN 06Z AND 08Z. WITH PASSAGE OF FRONTAL BOUNDARY...WINDS TO BECOME LIGHT AND VARIABLE FOR THE REST OF THE OVERNIGHT HOURS. SOME SHOWERS HAVE POPPED UP AHEAD OF FRONTAL BOUNDARY THIS EVENING...BUT SHOULD REMAIN JUST NORTH OF METRO AREA AND MOVE OUT BY 06Z...SO NO NEED TO MENTION IN TAFS. CIGS TO REMAIN VFR THROUGH FORECAST PERIOD. OTHERWISE...WINDS TO PICKUP FROM THE SOUTHEAST TO SOUTH BY MID MORNING SUNDAY AS FRONT SLIDES BACK NORTH AS A WARM FRONT. AS FOR PCPN CHANCES...BEST CHANCES WILL BE SUNDAY EVENING. BEST INSTABILITY AND LIFT WILL BE OVER CENTRAL MO...SO ADDED TSTM MENTION THERE AFTER 00Z MONDAY. AS FOR REST OF TAF SITES...NOT AS STRONG INSTABILITY...SO JUST ADDED PROB30 MENTION FOR SHOWERS FOR SUNDAY EVENING. SPECIFICS FOR KSTL...WEAK COLD FRONT IS SLIDING THROUGH REGION AND SHOULD BE MOVING THROUGH METRO AREA BY 08Z. WITH PASSAGE OF FRONTAL BOUNDARY...WINDS TO BECOME LIGHT AND VARIABLE FOR THE REST OF THE OVERNIGHT HOURS. SOME SHOWERS HAVE POPPED UP AHEAD OF FRONTAL BOUNDARY THIS EVENING...BUT SHOULD REMAIN JUST NORTH OF METRO AREA AND MOVE OUT BY 06Z...SO NO NEED TO MENTION IN TAF. CIGS TO REMAIN VFR THROUGH FORECAST PERIOD. OTHERWISE...WINDS TO PICKUP FROM THE SOUTHEAST BY 16Z SUNDAY AS FRONT SLIDES BACK NORTH AS A WARM FRONT. AS FOR PCPN CHANCES...BEST CHANCES WILL BE SUNDAY EVENING. NOT AS STRONG INSTABILITY OVER METRO AREA AT THIS TIME...SO JUST ADDED PROB30 MENTION FOR SHOWERS BETWEEN 01Z AND 05Z MONDAY. BYRD && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS BISMARCK ND
429 AM CDT SUN APR 7 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 329 AM CDT SUN APR 7 2013 THE MAIN FORECAST CHALLENGES FOR THE SHORT TERM INCLUDE PRECIPITATION TIMING AND TYPE. THE 00Z MODEL SUITE IS IN AGREEMENT...THUS HAVE UTILIZED A BLEND OF GUIDANCE. LATEST RADAR IMAGERY AT 330 AM CDT IS SHOWING SOME SCATTERED LIGHT RETURNS ACROSS THE SOUTHWEST....AND MORE WIDESPREAD LIGHT RETURNS OVER NORTHEASTERN MONTANA ASSOCIATED WITH A WEAK UPPER LEVEL IMPULSE. HOWEVER...SURFACE OBSERVATIONS HAVE NOT REFLECTED PRECIPITATION REACHING THE GROUND OVER THE SOUTHWEST. THE 05/06Z RAP SOLUTIONS DO NOT REFLECT THE LIGHT PRECIPITATION OVER THE NORTHEAST AT THIS TIME...BUT IT DOES PAINT SOME LIGHT PRECIPITATION ACROSS THE SOUTHWEST. THE 00Z GFS/ECMWF/NAM ALL SHOW LIGHT PRECIPITATION OVER NORTHEAST MONTANA AT THIS TIME...AND THUS HAVE UTILIZED A BLEND OF THE 00Z MODEL GUIDANCE IN ADDITION TO THE 05/06Z RAP GUIDANCE. PRECIPITATION WILL CONTINUE TO SPREAD EAST WITH TIME...FILLING IN OVER THE WEST OVER THE NEXT FEW HOURS...AND THEN OVER THE CENTRAL BY LATER THIS MORNING...AS THE UPPER LEVEL IMPULSE MOVES OVER THE AREA. LATEST OBSERVATIONS AT 400 AM CDT SHOW THAT TEMPERATURES SOUTH AND WEST OF THE MISSOURI RIVER REMAIN ABOVE FREEZING...WHILE NORTH AND EAST...TEMPERATURES ARE IN THE MID TO UPPER 20S. FOLLOWING THE COLD FRONTAL PASSAGE YESTERDAY...COLD AIR ADVECTION ALOFT IS UNDERWAY...WITH A SHALLOW WARM LAYER JUST ABOVE THE SURFACE. PRECIPITATION WILL START AS FREEZING RAIN...WITH SOME SNOW AND SLEET MIXED IN ACROSS THE WEST...BUT AS TEMPERATURES WARM ACROSS THE SOUTHWEST AND SOUTH CENTRAL...A TRANSITION TO RAIN WILL OCCUR. FOR LOCATIONS ACROSS THE NORTH...WHERE TEMPERATURES ARE CURRENTLY SUBFREEZING...PRECIPITATION WILL START AS SNOW...BUT AS TEMPERATURES WARM NEAR THE SURFACE WITH COLDER AIR PRESENT ALOFT...A TRANSITION TO FREEZING RAIN AND THEN TO A MIX OF FREEZING RAIN...SLEET...AND SNOW AFTER MIDNIGHT. EVEN THOUGH THE FORECAST PROCESS HAS LED TO INCREASED MIXED PRECIPITATION (SNOW...SLEET AND FREEZING RAIN) AND DECREASED COVERAGE OF FREEZING RAIN...HAVE DECIDED TO CONTINUE THE FREEZING RAIN ADVISORY AT THIS TIME. WILL CONTINUE TO MONITOR AND MAKE CHANGES IF WARRANTED. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 329 AM CDT SUN APR 7 2013 THE MAIN FORECAST PROBLEM IN THE EXTENDED PERIOD WILL MONDAY THROUGH MONDAY NIGHT...ACTUALLY BEGINNING LATE SUNDAY NIGHT IN THE FAR WEST. WILL LEAN MORE TOWARD A ECMWF/GEM SOLUTION OVER THE GFS/NAM FOR QPF DETAILS. ALTHOUGH THE STRONG UPPER LEVEL SYSTEM IN THE WEST DIVES SOUTH ON MONDAY...THERE IS STILL A PIECE OF UPPER LEVEL ENERGY THAT MAKES IT INTO THE NORTHERN PLAINS. DETERMINISTIC MODELS ARE IN REASONABLE AGREEMENT IN BRINGING THIS INTO THE LOCAL AREA. ALTHOUGH RATHER SIGNIFICANT DIFFERENCES IN THE RESULTING PLACEMENT OF THE QPF AS THE WAVE INTERACT WITH A TIGHTENING BAROCLINIC ZONE ACROSS WESTERN AND CENTRAL NORTH DAKOTA. THE NAM/GFS ARE FARTHER NORTH WITH THE QPF THAN THE GEM/ECMWF...ALTHOUGH THE 00 UTC SUNDAY ECMWF HAS COME A LITTLE FARTHER NORTH THAN PREVIOUS RUNS. LOOKING AT GFS BUFKIT SOUNDINGS...THERE DOES APPEAR TO BE A 3 TO 6 HOUR PERIOD WITH STRONG OMEGA OVER WITHIN THE SNOW GROWTH ZONE IN THE WEST CENTRAL AND SOUTHWEST...WHICH SHOULD YIELD SOME DECENT SNOW AMOUNTS. THIS AREA EXTENDS EAST ACROSS CENTRAL NORTH DAKOTA DURING THE DAY MONDAY BUT STRONG HIGH PRESSURE DROPPING SOUTH FROM CANADA WILL INHIBIT FG FORCING LATER IN THE DAY. THIS SHOULD REDUCE SNOW AMOUNTS AS THE WAVE MOVES EASTWARD INTO CENTRAL AND EASTERN NORTH DAKOTA. A COMBINATION OF HPC SNOW AMOUNTS WITH MODEL QPF YIELDS 3 TO 5 INCHES OF SNOW OVER MUCH OF WEST CENTRAL AND SOUTHWEST NORTH DAKOTA...WITH 2 TO 3 INCHES EXTENDING EAST INTO GRANT AND MORTON COUNTIES. SNOW TOTALS TAPER TO AN INCH OR TWO EAST OF THE MISSOURI RIVER. THE NORTHERN EXTENT OF THE HEAVIER SNOW REMAINS ALONG AND SOUTH OF LAKE SAKAKAWEA...WEST OF THE MISSOURI...THEN ALONG AND SOUTH OF THE I94 CORRIDOR EAST OF THE MISSOURI. ALTHOUGH SIGNIFICANT DIFFERENCES STILL REMAIN...FEEL CONFIDENT ENOUGH THAT A WINTER WEATHER ADVISORY IS WARRANTED OVER THE SOUTHWEST AND WEST CENTRAL. CONFIDENCE WANES AS YOU GO EAST...BUT WILL EXTEND THE ADVISORY EAST TO COVER MOST OF THE AREA WEST OF THE MISSOURI AND SOUTH OF THE LAKE. AT THIS TIME IT APPEARS THAT THERE SHOULD BE A QUICK TRANSITION FROM RAIN TO SNOW AS COLD AIR RUSHES SOUTH LATE SUNDAY NIGHT. HOWEVER...A PERIOD OF MIXED PRECIPITATION CANNOT BE RULED OUT BEFORE THE COLD AIR IS FIRMLY ENTRENCHED OVER THE AREA BY MONDAY MORNING. AS THE CANADIAN HIGH DROPS SOUTH WE SHOULD SEE A NICE ISALLOBARIC COMPONENT MOVE ACROSS THE WEST AND SOUTH CENTRAL ON MONDAY RESULTING IN SUSTAINED WINDS OF 15 TO 20 MPH AND GUST OF 25 TO 30 MPH. ALTHOUGH THERE IS NO LOOSE SNOW...WINDS WILL BE STRONG ENOUGH FOR SOME BLOWING SNOW AS IT FALLS. THUS WILL MAKE THE ADVISORY FOR SNOW AND BLOWING SNOW...LASTING FROM LATE SUNDAY NIGHT THROUGH LATE MONDAY NIGHT. AS THE MAIN UPPER LOW MOVES ONTO THE PLAINS ON TUESDAY...COLD HIGH PRESSURE OVER SASKATCHEWAN INTO NORTH DAKOTA SHOULD KEEP THE NORTHERN EXTEND OF THE SYSTEM RIGHT ALONG THE SOUTH DAKOTA BORDER WITH ANY SIGNIFICANT PRECIPITATION REMAINING SOUTH OF THE STATE. THEN AS THE SYSTEM BEGINS TO EJECT NORTHEAST TUESDAY NIGHT THE PRECIPITATION SHIELD TRIES TO PUSH A BIT FARTHER NORTH AND MAY CLIP THE FAR SOUTH AND SOUTHEAST COUNTIES WITH LIGHT SNOW. AT THIS TIME WE ARE KEEPING HIGH CHANCE POPS ALONG THE SOUTH DAKOTA BORDER...TAPERING TO SLIGHT CHANCE POPS AROUND INTERSTATE 94. THE NORTHERN HALF OF THE CWA IS EXPECTED TO REMAIN DRY TUESDAY AND TUESDAY NIGHT. TEMPERATURES DURING THIS PERIOD...MONDAY THROUGH WEDNESDAY...WILL BE BELOW NORMAL WITH 20S NORTH TO 30S SOUTH. WE DO SEE SOME SLIGHT WARMING BY AROUND THURSDAY AS THE SYSTEM EXITS TO OUR EAST...BUT A PROGRESSIVE NORTHWEST FLOW WILL BRING A SERIES OF UPPER LEVEL WAVES INTO THE AREA LATE IN THE WEEK KEEPING OUR WEATHER UNSETTLED WITH TEMPERATURES NEAR OR BELOW NORMAL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 329 AM CDT SUN APR 7 2013 WIDESPREAD STRATUS REMAINS OVER THE REGION THIS MORNING. THE MAIN HAZARDS TO AVIATION INCLUDE THE MVFR/IFR CONDITIONS ASSOCIATED WITH THE STRATUS...AND FREEZING RAIN AND MIXED PRECIPITATION EXPECTED TO MOVE INTO WESTERN NORTH DAKOTA AND THEN SPREAD EAST THROUGHOUT THE DAY. AS TEMPERATURES WARM AT KDIK...LIGHT FREEZING RAIN WILL GIVE WAY TO LIGHT RAIN. A BRIEF BREAK IN PRECIPITATION WILL BE POSSIBLE LATER THIS AFTERNOON...BEFORE THE NEXT ROUND OF LIGHT RAIN AND MIXED PRECIPITATION ARRIVES SUNDAY EVENING AND MONDAY MORNING. && .BIS WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 1 AM CDT /MIDNIGHT MDT/ MONDAY TO 1 AM CDT /MIDNIGHT MDT/ TUESDAY FOR NDZ017>020-031>034-040>044. FREEZING RAIN ADVISORY FROM 7 AM THIS MORNING TO 1 PM CDT THIS AFTERNOON FOR NDZ002-010-019>021-034-035-046. FREEZING RAIN ADVISORY UNTIL 11 AM CDT /10 AM MDT/ THIS MORNING FOR NDZ001-009-017-018-033-041. FREEZING RAIN ADVISORY FROM 11 AM THIS MORNING TO 7 PM CDT THIS EVENING FOR NDZ003-011-012-022-023-036-037-047-048-050-051. && $$ SHORT TERM...LTH LONG TERM...TWH AVIATION...LTH
AREA FORECAST DISCUSSION
NWS PORTLAND OR
305 AM PDT SUN APR 7 2013 .SYNOPSIS...A DEEPENING LOW PRESSURE SYSTEM IS MOVING ONSHORE NEAR THE LONG BEACH PENINSULA OF SOUTHERN WA...BRINGING INCREASINGLY STRONG WINDS TO THE OREGON COAST. GUSTY WINDS ARE BEGINNING TO SPREAD ACROSS THE COAST RANGE AND INTO THE WILLAMETTE VALLEY...THIS WILL BE THE TREND FOR THIS MORNING. SNOW IS FALLING IN THE HIGH CASCADES AND WILL INCREASE TODAY AS FLOW TURNS WESTERLY. SNOW LEVELS WILL BE NEAR OR BELOW THE CASCADE PASSES. ELSEWHERE RAIN WILL TAPER TO SHOWERS AND SCATTERED THUNDERSTORMS AS A COLD UPPER LEVEL LOW MOVES ONSHORE THIS AFTERNOON AND EVENING. THUNDERSTORMS MAY HAVE SMALL HAIL AND GUSTY WINDS THROUGH THIS EVENING. SHOWERS WILL LINGER INTO MONDAY...THEN TAPER OFF AS A RIDGE OF HIGH PRESSURE BUILDS FOR A DRIER AND WARMER WEATHER TUESDAY. ANOTHER SYSTEM IS EXPECTED TO BRING MORE RAIN WEDNESDAY. && .SHORT TERM...TODAY THROUGH WEDNESDAY...THE CIRCULATION OF A DEVELOPING LOW PRESSURE SYSTEM IS APPARENT ON KLGX/KRTX NWS DOPPLER RADARS...PRESENTLY MOVING INTO THE LONG BEACH PENINSULA OF PACIFIC COUNTY WA. THIS SYSTEM IS A LITTLE FARTHER NORTH AND A LITTLE STRONGER THAN MOST MODELS SUGGESTED...WITH BUOY 46029 AND HOME WEATHER STATIONS ON THE LONG BEACH PENINSULA REASONABLY SUGGESTING A CENTRAL PRESSURE OF ABOUT 997 MB. LATEST RUNS OF THE HRRR 3 KM MODEL DEPICT AN ELONGATED SHAPE TO THE LOW... EXTENDING FROM THE S WA COAST SOUTHWESTWARD. THIS APPEARS REASONABLE CONSIDERING THE WIND FIELD APPARENT ALONG THE COAST AND SHOWN BY BUOYS IN THE COASTAL WATERS. THUS THERE MAY BE A BIT OF A LULL TO THE WIND ALONG OUR NORTH COAST ZONES INITIALLY AS THE LOW MOVES ONSHORE. BEHIND THE LOW...HRRR AND NAM HAVE BEEN VERY INSISTENT ON A STRONG SURGE OF NW-W WIND IN THE BENT BACK OCCLUSION ON THE BACK SIDE OF THE LOW. THIS WILL CAUSE A SURGE OF WIND FROM THE SW-W AND EVENTUALLY NW WIND ALONG THE COAST IN THE COMING HOURS...SO IF ONE SURGE OF WIND EASES IT DOES NOT NECESSARILY MEAN THE EVENT IS OVER. THE CONSEQUENCES OF THE STRONGER LOW AND MORE NORTHERN TRACK WILL BE INCREASED CONFIDENCE IN THE WIND ADVISORY FOR THE WILLAMETTE VALLEY AND A LITTLE CONCERN THE STRONGER WINDS MAY PUSH INTO KELSO/LONGVIEW. ADDITIONALLY...IT APPEARS A LOW-END HIGH WIND WARNING WILL VERIFY FOR THE OREGON COAST AND COAST RANGE. WILL LEAVE ALL WIND HIGHLIGHTS AS IS FOR NOW...THE OVERALL FORECAST LOOKS PRETTY WELL ON TRACK WITH GUSTS 50-60 MPH WIDESPREAD FOR THE OR COAST AND LOCAL GUSTS TO 70 MPH FOR THE MOST EXPOSED AREAS. SOUTH WIND GUSTS 25-35 MPH ARE ALREADY DEVELOPING IN THE TUALATIN AND CENTRAL/SOUTH WILLAMETTE VALLEY. THESE WILL GET STRONGER WITH 35-45 MPH GUSTS LIKELY TO DEVELOP FOR THE WILLAMETTE VALLEY AND CLARK COUNTY WITHIN THE NEXT COUPLE HOURS.AS PRESSURE RISES BEGIN IN EARNEST. ASIDE FROM TRACKING THE LOW AND ASSOCIATED WIND PATTERN THE OTHER FORECAST CHALLENGES OF THE DAY ARE...1. HOW PROLIFIC THUNDERSTORMS WILL BE TODAY AND 2. HOW MUCH SNOW WILL FALL IN THE CASCADES. THUNDERSTORMS...NAM BUFR SOUNDINGS SHOW A VERY STRONG DIRECTIONAL SHEAR PROFILE WILL QUICKLY BECOME UNIDIRECTIONAL AS THE MORNING PROGRESSES. HOWEVER A SECONDARY TROUGH IS EXPECTED TO MOVE IN LATER THIS AFTERNOON AS THE COLD POOL ALOFT DIPS INTO WESTERN WA AND NORTHWEST OREGON. LAPSE RATES LOOK MARGINAL FOR THUNDERSTORMS...BUT IMPROVE AS THE AFTERNOON PROGRESSES. WITH SFC TEMPS IN THE LOW 50S WE SHOULD BE ABLE TO MUSTER ABOUT 400-600 J/KG OF CAPE AND LIFTED INDICES OF -2 TO -3 DEG C...WHICH WITH LITTLE TO NO CAPPING WOULD BE PLENTY TO SUGGEST DEEP CONVECTION. SO WE INCREASED THUNDERSTORM COVERAGE TO SCATTERED AS THIS SETUP IS ABOUT AS GOOD AS IT GETS IN A POST-FRONTAL ENVIRONMENT. WITH 25-35 KT WESTERLY FLOW AT 850 MB ANY ORGANIZED THUNDERSTORMS MAY MIX DOWN GUSTY WINDS. TERRAIN DRIVEN FLOW MAY PRODUCE A LITTLE DIRECTIONAL SHEAR AS WELL...WHICH COULD LEAD TO SOME WEAK ROTATION WITH THE STRONGER CELLS. ANY THUNDERSTORMS SHOULD DIE DOWN QUICKLY AFTER SUNSET AS SFC TEMPS COOL AND THE AIR MASS STABILIZES. SNOW...SNOW AMOUNTS IN THE CASCADES HAVE THUS FAR BEEN UNIMPRESSIVE WITH ABOUT 2-4 INCHES MOST LOCATIONS ABOVE 4000 FT. HOWEVER AS LOW PRESSURE CROSSES THE CASCADES FLOW WILL BECOME MORE OROGRAPHIC. WEST WINDS 25-35 KT AT 850 MB WILL ENHANCE SNOWFALL IN THE CASCADES...SO A GOOD 6-12 INCHES LOOK LIKELY ABOVE 4500-5000 FT BY LATER TONIGHT. SNOW LEVELS WILL BE LOWERING...SO THE PASSES COULD GET A FEW SLUSHY INCHES OF SNOW THIS AFTERNOON AND TONIGHT. SNOW WILL GRADUALLY TAPER OFF MONDAY. A WEAK SHORTWAVE MAY KEEP A FEW SHOWERS IN THE REGION THROUGH MONDAY. HOWEVER IT APPEARS WE WILL DRY OUT BY TUESDAY AS RIDGING BUILDS INTO OREGON AND WASHINGTON. 850 MB TEMPS REBOUND TO ABOUT +5 DEG C TUE AFTERNOON...PROBABLY ENOUGH FOR LOWER 60S IN THE VALLEYS. THIS RIDGE PROBABLY WILL NOT BE STRONG TO KEEP CLOUD COVER TO OUR NORTH...AND THE NORTH COAST MAY GET BRUSHED WITH SOME RAIN OR DRIZZLE TUE/TUE NIGHT. THE RIDGE COLLAPSES WEDNESDAY...ALLOWING ANOTHER FRONT TO SAG SOUTH AND SPREAD RAIN INTO OUR FORECAST AREA. WEAGLE .LONG TERM...MAIN CHANGES TO THE EXTENDED FORECAST WERE TO INCREASE POPS SLIGHTLY AS IT APPEARS WE REMAIN IN A ZONAL AND PROGRESSIVE PATTERN AFTER WEDNESDAYS FRONTAL SYSTEM. THIS MEANS NEAR OR SLIGHTLY BELOW NORMAL TEMPERATURES WITH RAIN AT TIMES FOR THE LATE WEEK PERIOD. WEAGLE && .AVIATION...EXPECT A MIX OF IFR AND MVFR CONDITIONS ALONG THE COAST THIS MORNING WITH A MIX OF MVFR AND VFR CONDITIONS FOR THE INTERIOR TAF SITES. A BURST OF HIGHER SOUTH WINDS SHOULD OCCUR FOR MOST TAF SITES IN THE NEXT 1 TO 4 HOURS...BEFORE SLOWLY RELAXING THROUGH THE DAY. CONDITIONS SHOULD BEGIN TO IMPROVE ON THE WHOLE AREA WIDE THIS AFTERNOON AS THE AIRMASS DESTABILIZES. HOWEVER...WITH THE AIRMASS DESTABILIZING...EXPECT SHOWERS TO PULSE UP AND DOWN...SOME OF WHICH WILL PRODUCE BRIEF HEAVY RAIN...SMALL HAIL AND LIGHTNING. THIS ACTIVITY SHOULD BEGIN TO WANE DURING THE EVENING HOURS. A RELATIVELY UNSTABLE AIRMASS WILL PERSIST INTO TONIGHT KEEPING MANY LOCATIONS VFR...WITH SOME PATCHY MVFR CIGS. KPDX AND APPROACHES...EXPECT A MIX OF MVFR AND VFR CONDITIONS THIS MORNING TO TRANSITION PRIMARILY TO VFR AROUND MIDDAY. EAST WINDS SHOULD SHIFT TO EAST...AND GUST PRETTY STRONGLY OUT OF THE SOUTH STARTING AROUND 5 AM. THERE IS A CHANCE FOR A THUNDERSTORM TO IMPACT THE TERMINAL THIS AFTERNOON AND EARLY EVENING. OTHERWISE...A RELATIVELY UNSTABLE AIRMASS TONIGHT SHOULD KEEP CIGS HIGH END MVFR OR VFR OVERNIGHT. /NEUMAN && .MARINE...AN ELONGATED BOOMERANG LOOKING LOW PRESSURE IS CURRENTLY PUSHING ASHORE NEAR THE COLUMBIA RIVER MOUTH. GALE FORCE WINDS HAVE PRIMARILY REMAINED SOUTH OF THE LOW PRESSURE...ALTHOUGH EASTERLY WINDS REACHED INTO GALE FORCE BRIEFLY AT BUOY 29 EARLIER THIS MORNING. A HIGH RESOLUTION MODEL CONTINUES TO INSIST A BURST OF HIGHER WINDS ON THE BACKSIDE OF THE LOW PRESSURE WILL SWING INTO THE CENTRAL OREGON COAST AROUND 4 AM. AS A RESULT...WINDS MAY TEMPORARILY SPIKE IN THE NEXT HOUR OR TWO ACROSS THE NORTH CENTRAL OREGON WATERS BEFORE BEGINNING TO SUBSIDE BETWEEN 5 AM AND 8 AM. EXPECT WIND GUSTS OF 20 TO 30 KT TO CONTINUE AREA WIDE TODAY WITH SEAS REMAINING ABOVE 10 FT. HIGH PRESSURE WILL THEN BEGIN TO BUILD INTO THE REGION MONDAY...CAUSING WINDS TO SUBSIDE AND SEAS TO RELAX. THIS SHOULD CONTINUE UNTIL MIDDAY TUESDAY WHEN A WEAKENING FRONT BRINGS A BURST OF 20 TO 25 KT WINDS TO PRIMARILY THE NORTHERN WATERS. ANOTHER STORM SYSTEM WILL SLIDE BY TO OUR NORTH WEDNESDAY...CAUSING SOUTH WINDS TO INCREASE ONCE AGAIN AND SEAS TO BRIEFLY POP UP NEAR 10 FT. HIGH PRESSURE SHOULD THEN CAUSE WINDS AND SEAS TO RELAX LATE IN THE WORK WEEK. /NEUMAN && .PQR WATCHES/WARNINGS/ADVISORIES... OR...WINTER WEATHER ADVISORY UNTIL 11 PM PDT THIS EVENING FOR CASCADES IN LANE COUNTY-NORTHERN OREGON CASCADES. WIND ADVISORY UNTIL 11 AM PDT THIS MORNING FOR CENTRAL WILLAMETTE VALLEY-GREATER PORTLAND METRO AREA-SOUTH WILLAMETTE VALLEY. HIGH WIND WARNING UNTIL 11 AM PDT THIS MORNING FOR CENTRAL COAST RANGE OF WESTERN OREGON-COAST RANGE OF NORTHWEST OREGON. HIGH WIND WARNING UNTIL 8 AM PDT THIS MORNING FOR CENTRAL OREGON COAST-NORTH OREGON COAST. WA...WINTER WEATHER ADVISORY UNTIL 11 PM PDT THIS EVENING FOR SOUTH WASHINGTON CASCADES. WIND ADVISORY UNTIL 11 AM PDT THIS MORNING FOR GREATER VANCOUVER AREA. PZ...GALE WARNING UNTIL 8 AM PDT THIS MORNING FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM. SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 10 PM PDT THIS EVENING. && MORE WEATHER INFORMATION ONLINE AT... HTTP://WEATHER.GOV/PORTLAND THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
342 AM CDT SUN APR 7 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 342 AM CDT SUN APR 7 2013 CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED UPPER TROUGHING APPROACHING THE PACIFIC NORTHWEST...WEAK RIDGING OVER THE NORTHERN U.S. ROCKIES INTO THE DAKOTAS...AND A SHORTWAVE TROUGH OVER EASTERN WISCONSIN. ALSO OF NOTE ON WATER VAPOR WERE A PAIR OF SHORTWAVES MOVING THROUGH THE WEAK RIDGING...ONE IN SOUTH CENTRAL WYOMING AND THE OTHER IN NORTHWEST COLORADO. THE FORECAST AREA LIES IN SUBSIDENCE IN THE WAKE OF THE EASTERN WISCONSIN SHORTWAVE TROUGH...SEEN AS AN INVERSION BETWEEN 775 AND 850MB ON THE 00Z MPX SOUNDING. THIS INVERSION WAS ALSO SATURATED... REFLECTED TOO BY PLENTY OF STRATUS CLOUDS ON 11-3.9UM IMAGERY FROM THE EASTERN DAKOTAS INTO THE FORECAST AREA. COOLER AIR HAS BEEN FILTERING IN BEHIND THE SHORTWAVE AS WELL WITH 850MB TEMPS NOW DOWN TO +2 TO -3C ACROSS THE FORECAST AREA PER RAP ANALYSIS...COLDEST OVER CENTRAL WISCONSIN. AT THE SURFACE...HIGH PRESSURE WAS SEEN DROPPING SOUTH INTO WESTERN MINNESOTA...IN THE WAKE OF LOW PRESSURE OVER NORTHERN LAKE MICHIGAN AND ITS COLD FRONT WHICH EXTENDS SOUTHWEST TO KANSAS CITY. A PATTERN CHANGE IS FORECAST TO OCCUR ALOFT DURING THE NEXT 24 HOURS AS THE UPPER TROUGH SEEN OFF THE PACIFIC NORTHWEST SHARPLY DIGS SOUTH INTO CALIFORNIA AND NEVADA. IN RESPONSE...RIDGING WILL BUILD DOWNSTREAM...ADJUSTING THE UPPER LEVEL FLOW TO SOUTHWESTERLY OVER THE FORECAST AREA. THIS MEANS THAT THE RECENT LOW LEVEL COLD ADVECTION WILL COME TO AN END SHORTLY...WITH WARM ADVECTION PROGGED TO BEGIN BETWEEN 12-18Z TODAY AND CONTINUE THROUGH TONIGHT. IN ADDITION...MODELS HAVE BEEN CONSISTENT IN SHOWING THE PAIR OF SHORTWAVES SEEN IN WYOMING AND COLORADO TO AFFECT THE FORECAST AREA LATE TONIGHT AS THEY RIDE THROUGH THE SOUTHWEST FLOW. THE FIRST TWO ISSUES FOR THE SHORT TERM PERIOD ARE THE CLOUDS AND HIGH TEMPERATURES TODAY. THE PRESENT STRATUS DECK DOES HAVE SOME HOLES IN IT ON ITS SOUTHERN SIDE. THESE HOLES SHOULD EXPAND THROUGH THE MORNING AS DIURNAL MIXING COMMENCES. 07.00Z NAM LOW LEVEL RH FIELDS...WHICH GENERALLY TEND PESSIMISTIC...ALSO SUGGEST THAT THE STRATUS DECK WILL MOSTLY MIX OUT BY 18Z SOUTH OF US HIGHWAY 10. LATER IN THE AFTERNOON...SAY 21Z AND AFTER...MID AND HIGH CLOUDS CURRENTLY SPREADING INTO THE PLAINS STATES ARE PROGGED TO MOVE INTO THE FORECAST AREA. THUS WE SHOULD SEE AT LEAST A FEW HOURS OF MOSTLY SUNNY SKIES TODAY. WITH 850MB TEMPS CLIMBING TO 0C NORTH AND 6C SOUTH BY 18Z...ANTICIPATING THAT MOST LOCATIONS MINUS NORTH OF HIGHWAY 10 WHERE MORE CLOUDS AND SNOW EXIST WILL CLIMB INTO THE 50S. WARMEST TEMPERATURES...APPROACHING 60...ARE EXPECTED IN THE FAR SOUTH. THE NEXT ISSUE FOR THE SHORT TERM PERIOD IS THE POTENTIAL FOR PRECIPITATION VERY LATE THIS AFTERNOON INTO TONIGHT...DUE TO THE WARM ADVECTION PATTERN AND THE APPROACH OF THE PAIR OF SHORTWAVES. THE 07.00Z GFS/06.12Z ECMWF ALREADY SHOW HINTS OF WARM ADVECTION / ISENTROPICALLY INDUCED PRECIPITATION AFFECTING FAR WESTERN PORTIONS OF THE FORECAST AREA BETWEEN 21-00Z TODAY. THINKING THIS MIGHT BE A BIT FAST...WITH THE 07.00Z NAM/REGIONAL CANADIAN/HIRES-ARW AND 07.03Z SREF ALL SLOWER. THUS...PLAN ON KEEPING CONDITIONS DRY TIL 00Z. AS WE HEAD THROUGH TONIGHT...THERE IS A STRONG CONSENSUS AMONGST ALL MODEL GUIDANCE OF A PRECIPITATION SPLIT. THE NORTHERN AREA TRACKS FROM NORTHWEST IA/SOUTHERN MN INTO NORTHWEST WISCONSIN. THE SOUTHERN AREA TRACKS FROM NORTHERN MISSOURI INTO SOUTHEAST IA AND NORTHWEST IL. THIS SPLIT APPEARS TO BE A RESULT OF HOW THE PAIR OF SHORTWAVES APPROACHING THE FORECAST AREA LATE TONIGHT INTERACT WITH THE ISENTROPIC LIFT PATTERN IN PLACE. 850MB MOISTURE TRANSPORT FIELDS SHOW THE SPLIT INTERACTION WITH THE ISENTROPIC LIFT PATTERN NICELY. IN ADDITION...THERE ARE OTHER SUPPORTING FEATURES. FOR EXAMPLE...THE NORTHERN AREA BECOMES INFLUENECED BY A DEVELOPING AND STRENGTHENING UPPER JET STREAK OVER UPPER MICHIGAN...PLACING IT IN THE FAVORABLE RIGHT ENTRANCE REGION. MEANWHILE...THE SOUTHERN AREA HAS A STRONG LOW TO MID- LEVEL FRONTOGENESIS FEATURE ALONG THE PRESENT COLD FRONT NEAR I-70...WHICH FOR ALL INTENSIVE PUPROSES TURNS INTO A STATIONARY BOUNDARY. SO FOR THE FORECAST...THIS WELL AGREED UPON SPLIT PRECIPITATION SCENARIO POSES A PROBLEM FROM WHAT WE HAD GOING PREVIOUSLY. HAVE ADJUSTED PRECIPITATION CHANCES AND QPF QUITE A BIT LOWER SOUTH OF I-90...SINCE THIS AREA WILL BE ON THE SUBSIDENT SIDE OF THE F-GEN CIRCULATION. NOTE THAT MODELS LIKE THE 07.00Z GFS/REGIONAL CANADIAN EVEN SUGGEST THAT SOME LOCATIONS ACROSS NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN COULD END UP DRY. REGARDING PRECIPITATION TYPE...ALL OF IT SHOULD FALL AS RAIN WITH WET-BULB ZERO HEIGHTS PROGGED WELL ABOVE 2000 FT. THE PREVIOUS FORECAST INTRODUCED A CHANCE FOR THUNDER AND THIS STILL LOOKS REASONABLE AFTER MIDNIGHT...WITH POTENTIAL FOR A FEW HUNDERED J/KG OF SKINNY CAPE LIFTED FROM 850MB. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 342 AM CDT SUN APR 7 2013 OVERALL MUCH OF THE LONG TERM PERIOD LOOKS ACTIVE...THANKS TO THAT TROUGH DIGGING INTO CALIFORNIA AND NEVADA TONIGHT. QUITE A FEW DETAILS TO NOTE. ON MONDAY...THE PAIR OF SHORTWAVES ARE PROGGED TO SHIFT EAST INTO MICHIGAN DURING THE AFTERNOON...TAKING THE BULK OF THE SPLIT PRECIPITATION TONIGHT WITH THEM. HOWEVER...THE STORY DOES NOT END THERE. THE FOCUS TURNS TO THE FRONTAL BOUNDARY NEAR I-70...WHICH BY ALL MODELS IS SUGGESTED TO LIFT NORTH INTO CENTRAL AND PERHAPS NORTHERN IA DURING THE AFTERNOON. THE LIFTING NORTH IS A RESULT OF THE UPPER TROUGHING DEEPENING AND DIGGING INTO THE FOUR CORNERS REGION...ENHANCING THE WARM ADVECTION DOWNSTREAM. THE 07.00Z REGIONAL CANADIAN AND NAM SUGGEST THERE IS POTENTIAL FOR SURFACE BASED CONVECTION TO FIRE ON THIS FRONT. THE 07.00Z GFS...ON THE OTHER HAND...HAS A FARTHER SOUTH FRONT AND KEEPS THINGS MORE CAPPED. HOWEVER...ALL THREE MODELS INCLUDING THE 06.12Z ECMWF DEPICT POTENTIAL FOR FRONTOGENETICALY INDUCED PRECIPITATION NORTH OF THE FRONTAL BOUNDARY. THUS...A NEED CONTINUES FOR CHANCES OF SHOWERS ALONG WITH THE THUNDERSTORM MENTION IN THE EVENT THE REGIONAL CANADIAN/NAM PAN OUT. IF THE REGIONAL CANADIAN/NAM PAN OUT... CERTAINLY COULD NOT RULE OUT SOME SEVERE POTENTIAL GIVEN 0-6 KM SHEAR UPWARS OF 45-50 KT. HOWEVER...IT SEEMS LIKE THE BETTER INSTABILITY IS WEST OF THE FORECAST AREA...THUS KEEPING THE BULK OF THE SEVERE POTENTIAL TO THE WEST. SPC DAY 2 SEVERE PROBABILITIES DEPICT THIS AS WELL. DEFINITELY SOMETHING TO KEEP AN EYE ON....THOUGH. TEMPERATURE FORECAST IS TRICKY AS IT DEPENDS ON THE FRONTAL POSITION. A NAM/REGIONAL CANADIAN OR EVEN ECMWF SOLUTION WOULD ALLOW FOR HIGHS IN THE 60S TO POSSIBLY 70 ALONG/SOUTH OF I-90. THE GFS IS A LITTLE COOLER BUT STILL HAS HIGHS IN THE 60S SOUTH OF I-90. RAISED HIGHS 5 DEGREES OR SO TO COME BETTER IN AGREEMENT WITH ALL 07.00Z GUIDANCE...BUT THEY MAY NEED TO BE RAISED MORE... ESPECIALLY IF MORE SUN OCCURS IN THE AFTERNOON. THINGS GET MORE INTERESTING HEADING INTO THE MONDAY NIGHT THROUGH THURSDAY TIME PERIOD. DURING THIS PERIOD...ALL MODELS HAVE THE DEEP UPPER TROUGH OVER THE FOUR CORNERS SLOWLY LIFTING TO THE EAST-NORTHEAST. MEANWHILE...AT THE SAME TIME THERE IS A DEEP UPPER TROUGH HANGING AROUND THE HUDSON BAY INTO NORTHERN ONTARIO AREA... HELPING TO HOLD AN UPPER JET STREAK IN PLACE OVER THE NORTHERN GREAT LAKES. THIS MEANS THE FORECAST AREA IS GOING TO BE PLACED IN THE FAVORABLE RIGHT ENTRANCE REGION UNTIL THE UPPER TROUGH MOVES IN. MONDAY NIGHT FOR THE MOST PART LOOKS QUIET...WITH ANY SHOWERS AND POSSIBLE THUNDERSTORMS IN THE EVENING DISSIPATING WITH LOSS OF DAYTIME HEATING. THE FRONTAL BOUNDARY...IF IT IS NEARBY...LOOKS TO SLOWLY DROP SOUTH MONDAY NIGHT FORCED BY THAT DEEP UPPER TROUGH TO OUR NORTH. IT APPEARS THERE MAY BE A MASS OF LOW LEVEL STRATUS THAT MOVES IN BEHIND THE FRONT...AND WITH LOW LEVEL FRONTOGENESIS BEHIND THE FRONT WE COULD DEAL WITH SOME LIGHT RAIN OR DRIZZLE. PRECIPITATION CHANCES DEFINITELY GO ON THE INCREASE FROM SOUTHWEST TO NORTHEAST THROUGH THE DAY TUESDAY AND INTO TUESDAY NIGHT...IN RESPONSE TO ISENTROPIC LIFT STRENGTHENING DOWNSTREAM OF THE UPPER TROUGH PUSHING TO THE EAST-NORTHEAST. SOME CONCERN FOR SOME HEAVIER RAIN TUESDAY NIGHT...ESPECIALLY ACROSS THE SOUTH...AS PRECIPITABLE WATER VALUES INCREASE OVER 1 INCH AND SOME WEAK ELEVATED INSTABILITY MOVES IN FOR THUNDERSTORMS. RAISED BOTH PRECIPITATION CHANCES AND QPF FOR TUESDAY AND ESPECIALLY TUESDAY NIGHT GIVEN THE STRONG SIGNAL AMONGST THE 07.00Z ECMWF/GFS/CANADIAN MODELS. FROM WEDNESDAY INTO THURSDAY...THE CORE OF THE UPPER TROUGH IS PROGGED TO SLOWLY APPROACH THE FORECAST AREA. AS THIS OCCURS...THE FORECAST AREA EVENTUALLY ENDS UP ON THE NORTHWEST / COLD SIDE OF A SURFACE LOW TRACKING TO OUR SOUTH...PLACING THE AREA INTO THE TROWAL AND COLD CONVEYOR BELT REGION. GIVEN THE GOOD MODEL AGREEMENT AGAIN...RAISED PRECIPITATION CHANCES UP DURING THIS PERIOD. IN ADDITION...WILL HAVE TO WATCH FOR SOME SNOW ACCUMULATIONS COME WEDNESDAY NIGHT AND THURSDAY AS 850MB TEMPS DROP TO -4 TO -8C BY 12Z THURSDAY. IT SHOULD BE NOTED THAT THE 07.00Z NAM IS AN OUTLIER SOLUTION TO THE ABOVE SCENARIO...PARTICULARLY FOR TUESDAY THROUGH WEDNESDAY...SINCE IT EJECTS THE CORE OF THE SOUTHWESTERN TROUGH MUCH QUICKER AND LIFTS IT FARTHER NORTH. THE NAM WAS DISCOUNTED GIVEN GOOD MODEL AGREEMENT BETWEEN ALL OTHER MODELS. THE 07.03Z SREF LOOKS LIKE A COMPROMISE BETWEEN THE NAM AND GFS...BUT THE SREF IS NAM-BIASED DUE TO AN OVERWHELMING AMOUNT OF NAM MEMBERS. THUS...THE SREF WAS DISCOUNTED AS WELL. LOOKING FARTHER AHEAD...GOOD MODEL AGREEMENT EXISTS AMONGST THE 07.00Z ECMWF/GFS/CANADIAN ON BRINGING COLD CANADIAN HIGH PRESSURE INTO THE AREA THURSDAY NIGHT THROUGH FRIDAY NIGHT. THIS SHOULD HELP DRY THINGS OUT. LEFT A CONSENUS 20 PERCENT CHANCE OF PRECIPITATION IN THURSDAY NIGHT...BUT THIS PERIOD MAY EVENTUALLY END UP DRY. WILL NEED TO WATCH SOME OF THE LOW TEMPERATURES TOO FOR BOTH THURSDAY NIGHT AND FRIDAY NIGHT...DEPENDING ON HOW MUCH FRESH SNOW WE PICK UP AND FOR FRIDAY NIGHT HOW MUCH IS STILL ON THE GROUND. A WARM ADVECTION PATTERN SETS UP FOR SATURDAY AHEAD OF NEW TROUGHING DROPPING INTO THE NORTHERN ROCKIES. FOLLOWED THE CONSENSUS HERE OF BRINGING SOME 20-30 PERCENT CHANCES OF PRECIPITATION ACROSS THE AREA ON SATURDAY. NEED TO MAINTAIN A RAIN/SNOW MIX BECAUSE 850MB TEMPS ARE STILL SLOW TO WARM...ESPECIALLY IN THE ECMWF WHERE IT KEEPS THEM BELOW 0C THROUGH 00Z SUNDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1015 PM CDT SAT APR 6 2013 THERE WILL BE A DECREASE IN THE WINDS OVERNIGHT AS THE PRESSURE GRADIENT SLACKENS. MVFR CIGS FROM 1500-2500 WILL CONTINUE...BUT SEE SOME THREAT FOR SUB 1 KFT CIGS AT KRST. NOT CONFIDENT ENOUGH TO ADD TO THE FORECAST...BUT TRENDS WILL BE WATCHED CLOSELY. THE LOW CIGS WILL HANG INTO SUNDAY MORNING. BUFKIT SOUNDINGS VIA THE RAP13/NAM/GFS ALL SUGGEST SOME MIXING BY 18Z...WHICH WOULD HELP BREAK UP THE CLOUDS...INCREASING THE CHANCES FOR SCT CONDITIONS FOR THE AFTERNOON. WILL STAY WITH THIS TREND. MORE UPPER LEVEL ENERGY WILL SPIN ACROSS THE REGION SUNDAY NIGHT/MON. CLOUDS WILL QUICKLY RETURN SUNDAY EVENING AS A RESULT...WITH RAIN CHANCES MOVING IN BETWEEN 06-12Z MONDAY. THERE MIGHT BE ENOUGH INSTABILITY/FORCING FOR AN ISOLATED THUNDERSTORM...BUT NOT ENOUGH OF A CHANCE TO INCLUDE IN THE FORECAST. IT SHOULD BE NOTED THAT THE NAM/GFS/ECMWF ALL SUGGEST THAT THERE COULD BE TWO MAIN REGIONS FOR PCPN...WHICH WOULD GO NORTH AND SOUTH OF THE TAF SITES. STILL WOULD BE ENOUGH FORCING FOR SOME -SHRA CHANCES...BUT ACCUMS AND IMPACTS TO VSBYS WOULD BE MUCH LESS. && .HYDROLOGY... ISSUED AT 342 AM CDT SUN APR 7 2013 RIVER STATUS... THE TREMPEALEAU RIVER NEAR DODGE WILL REMAIN ABOVE FLOOD STAGE AND ALLOW FOR MINOR FLOODING TO CONTINUE THROUGH MONDAY MORNING. MEANWHILE ON THE BLACK...ANOTHER BRIEF ICE JAM LOOKS LIKE IT MAY HAVE FORMED AROUND NEILLSVILLE...WITH A SPIKE UP OF 4 FEET BUT STILL WELL WITHIN THE RIVER BANK. DOWNSTREAM...SO FAR THE BLACK REMAINS WITHIN THE RIVER BANK. SNOW PACK... RECENT COOPERATIVE OBSERVER REPORTS SHOW SNOW PACK IS MAINLY ALONG AND NORTHEAST OF THE INTERSTATE 94 CORRIDOR WITH 2 TO 7 INCHES OF SNOW DEPTH IN PLACES. THE DEEPEST SNOW PACK IS OVER THE NORTHERN MOST PARTS OF TAYLOR WHERE AROUND A FOOT OF SNOW REMAINS ON THE GROUND. SNOW WATER EQUIVALENT OF 1 TO 2 INCHES IS MAINLY NORTH OF THE INTERSTATE 94 CORRIDOR WITH THE GREATEST SNOW WATER EQUIVALENT OF 2 TO 4 INCHES IN NORTHERN TAYLOR COUNTY. RAINFALL... LESS RAINFALL IS ANTICIPATED TONIGHT INTO MONDAY THAN PREVIOUSLY EXPECTED...WITH UPWARDS OF 1/4 TO 1/2 INCH NORTH OF I-90 AND LESS THAN A 1/4 INCH TO THE SOUTH. WILL STILL NEED TO WATCH TUESDAY THROUGH WEDNESDAY...THOUGH. BY WEDNESDAY MORNING...CURRENTLY ANTICIPATING AMOUNTS BETWEEN 3/4 INCH AND 1.25 INCHES SOUTH OF HIGHWAY 10 TO LESS THAN A 1/2 INCH TO THE NORTH. IF THE SYSTEM BRINGING THIS RAIN SHIFTS FARTHER NORTH...THE HEAVY RAIN AREA WILL SHIFT NORTH AS WELL...PLACING IT WHERE RAIN IS NOT NEEDED. TEMPERATURES... HIGHS TODAY ARE GOING TO BE COOLER...IN THE THE MIDDLE 40S/AROUND 50 NORTH OF I-94 AND IN THE 50S SOUTH OF THERE. WARMER CONDITIONS LOOK ON TAP FOR MONDAY...WITH MOSTLY 50S NORTH OF I-94 AND 60S SOUTH. TEMPERATURES THEN COOL INTO THE 40S FOR TUESDAY AND WEDNESDAY AND POSSIBLY STRUGGLE TO GET TO 40 BY THURSDAY. THE TEMPERATURE MAY NOT MATTER IN A FEW DAYS AS MOST OF THE SNOW PACK MAY BE GONE...UNTIL POTENTIALL A SMALL SNOW PACK RE-ESTABLISHES ITSELF THURSDAY MORNING. FROST DEPTH... AS OF APRIL 4TH...FROST DEPTHS //WHICH ARE OBSERVED EVERY MONDAY AND THURSDAY//ACROSS THE AREA REMAIN DEEP...AVERAGING AROUND 1 FOOT TO 1 1/2 FEET SOUTH OF I-90...AND UP TO 3 FEET ACROSS PORTIONS OF NORTH CENTRAL WISCONSIN. THIS FROST WILL ACT TO ENHANCE RUNOFF OF SNOW MELT AND PRECIPITATION INTO STREAMS AND RIVERS. SUMMARY... MAIN CONCERN FOR FLOODING REMAINS ALONG THE TREMPEALEAU AND BLACK RIVERS AS SNOW MELT CONTINUES...ALONG WITH THE PERIODS OF RAINFALL TONIGHT INTO MONDAY AS WELL AS TUESDAY THROUGH WEDNESDAY. HAVE A HYDROLOGIC OUTLOOK PRODUCT OUT TO HEIGHTEN THIS AWARENESS. ALTHOUGH THE TUESDAY INTO WEDNESDAY MODERATE TO HEAVY RAIN IS FORECAST MAINLY SOUTH OF I-90...CURRENTLY THINKING THAT THE RIVERS SHOULD BE ABLE TO ABSORB IT. A QUICK MODEL OF THE TURKEY RIVER AT GARBER USING THE FORECAST QPF WOULD BRING THE RIVER ABOVE ACTION STAGE BUT NOT TO FLOOD. THUS...DID NOT EXPAND THE HYDROLOGIC OUTLOOK SOUTH. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION.....RIECK HYDROLOGY...AJ
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
1120 AM EDT SUN APR 7 2013 .UPDATE (REST OF TODAY AND TONIGHT)... BENIGN WEATHER WILL CONTINUE THROUGH TONIGHT WITH DRY CONDITIONS AND SEASONABLE TEMPERATURES. 15Z WATER VAPOR AND H4 RAP ANALYSIS SHOW AN UNAMPLIFIED UPPER LEVEL PATTERN IN PLACE OVER THE CONUS OUTSIDE OF A FEW MINOR SHORTWAVE "KINKS" IN THE FLOW. ZONAL FLOW IS IN PLACE OVER THE NORTHERN GULF COAST AND FLORIDA PENINSULA AND WILL HOLD FOR AT LEAST THE NEXT 24 HOURS. ONE VERY MINOR IMPULSE WITHIN THE ZONAL FLOW IS LOCATED OVER THE CENTRAL/EASTERN GULF AND WILL PASS OVER THIS EVENING/TONIGHT. WE HAVE SEEN A FEW HIGH LEVEL CIRRUS OUT AHEAD OF THIS FEATURE... HOWEVER AS IT APPROACHES...THE SYNOPTIC SUPPORT FOR THIS CIRRUS IS ALREADY BEGINNING TO PASS BY. AT THE SURFACE...HIGH PRESSURE EXTENDS DOWN THE EASTERN SEABOARD AND CONTINUES TO RIDGE ALL THE WAY TO THE FL PENINSULA AND CENTRAL/EASTERN GULF. GRADIENT AROUND THIS RIDGE IS PROVIDING A GENERAL EASTERLY WIND PATTERN. SIMILAR TO SATURDAY...STILL HAVE A RATHER MOIST LAYER SEEN ON TIME HEIGHT/CROSS SECTION ANALYSIS BETWEEN AROUND 950-985MB. THE 12Z KTBW SOUNDING PROFILE CONFIRMS THIS NWP FORECAST. WITH THE MOISTURE IN PLACE...AS DIURNAL HEATING CONTINUES TO MIX UP INTO THE COLUMN WE SHOULD AGAIN SEE A SHALLOW SCT-BKN CU FIELD EXPANDING ACROSS THE PENINSULA FROM EAST TO WEST DURING THE NEXT SEVERAL HOURS. MIXED ON SATURDAY TO AROUND 800MB PER 00Z KTBW SOUNDING. EXPECT SIMILAR MIXING TODAY...WHICH WITH 800-850MB TEMPS AROUND 9-10C WILL MIX DOWN TO HIGH TEMPERATURES IN THE LOWER 80S FOR MANY LOCATIONS...EVEN SOME MIDDLE 80S FOR THE FAR SOUTHERN ZONES WHERE LOW LEVEL COLUMN IS EVEN WARMER. THE STRONG TERRESTRIAL HEATING SHOULD FORCE AN ONSHORE COMPONENT SEA-BREEZE TO DEVELOP DURING THE EARLY AFTERNOON...AND THIS WILL KEEP THE BEACHES SEVERAL DEGREES COOLER WITH THE FLOW OFF THE SHELF WATERS. QUIET AND SEASONABLE OVERNIGHT PERIOD ON TAP. MOSTLY CLEAR SKIES EXPECTED WITH TEMPERATURES DROPPING TO THE MIDDLE AND UPPER 50S FOR MANY INLAND LOCATIONS BY SUNRISE...AND HOLDING IN THE 60S AT THE COAST FROM PINELLAS COUNTY SOUTHWARD ALONG THE SUN COAST. ENJOY! && .AVIATION... VFR CONDITIONS UNDER SCT CU/SC AND OCNL BKN CIRRUS. EAST AND SE WINDS SHIFT TO WESTERLY AT COASTAL TERMINALS IN THE AFTERNOON...AT 10KT OR LESS. && .MARINE... THE EASTERN GULF OF MEXICO WILL REMAIN ON THE SOUTHERN SIDE OF A RIDGE AXIS EXTENDING OFF THE GA/SC COAST THROUGH THE NEXT SEVERAL DAYS. RESULTING GRADIENT WILL PROVIDE A GENERAL EASTERLY FLOW TO THE REGION...HOWEVER MARINERS SHOULD ANTICIPATE WINDS BECOMING LOCALLY ONSHORE THE NEXT COUPLE OF AFTERNOON NEAR THE COAST WITH THE DEVELOPMENT OF THE SEA-BREEZE. THE NEXT FRONT WILL NOT APPROACH THE REGION UNTIL THE LATTER PORTION OF THE WEEK WITH SOUTHEAST AND SOUTH WINDS INCREASING AHEAD OF THIS SYSTEM. && .PRELIMINARY POINT TEMPS/POPS... TPA 79 63 83 65 / 0 10 0 0 FMY 82 63 85 63 / 10 0 0 0 GIF 82 61 85 62 / 10 0 10 10 SRQ 79 61 82 63 / 10 0 0 0 BKV 82 55 84 57 / 10 10 10 10 SPG 79 66 83 68 / 10 0 0 0 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ UPDATE/MARINE...MROCZKA AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
633 AM EDT SUN APR 7 2013 .SYNOPSIS... HIGH PRESSURE WILL PERSIST THROUGH MID WEEK. A COLD FRONT WILL APPROACH THE AREA LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THROUGH SUNRISE...SATELLITE...SOUTH CAROLINA DOT WEBCAMS AND SURFACE OBSERVATIONS SHOW LOW CLOUDS AND DENSE FOG ARE EXPANDING RAPIDLY SOUTH OUT OF BERKELEY COUNTY. THE BERKELEY COUNTY WARNING POINT AS WELL AS AWOS OBSERVATIONS FROM KMKS AND KDYB INDICATE VSBYS ARE RUNNING ABOUT 1/4-1/2 MILE. A DENSE FOG ADVISORY HAS BEEN ISSUED FOR DORCHESTER AND BERKELEY COUNTIES UNTIL 9 AM...BUT MAY NEED TO BE EXPANDED TO INCLUDE CHARLESTON AND COLLETON COUNTIES PRIOR TO SUNRISE. UPDATED GRIDDED AND TEXT FORECASTS TO REFLECT GOING TRENDS. TODAY...LARGE SOUTHWEST-NORTHEAST ORIENTED HIGH PRESSURE CENTERED OFF NEW ENGLAND WILL STEADILY SHIFT FARTHER OFFSHORE TODAY AS A FAIRLY ZONAL FLOW DOMINATES ALOFT. ONGOING WEAK WARM ADVECTION WILL PUSH H8 TEMPERATURES INTO THE 8-9C RANGE WHICH WILL YIELD SLIGHTLY WARMER HIGH TEMPERATURES COMPARED TO SATURDAY. LOW-LEVEL THICKNESSES SCHEMES AND MODEL BUFR SOUNDINGS GENERALLY SUPPORT HIGHS IN THE LOWER-MID 70S WITH CONSIDERABLY COOLER TEMPERATURES IN THE LOWER 60S AT THE BEACHES WHERE OCEANIC INFLUENCES WILL BE THE GREATEST. EXPECT ANOTHER RATHER ROBUST SEA BREEZE CIRCULATION TO FORM ALONG THE BEACHES LATER TODAY WHICH WILL MOVE STEADILY INLAND DURING THE AFTERNOON HOURS. THIS WILL CAUSE TEMPERATURES TO DROP ABOUT 5-8 DEGREES ACROSS THE COASTAL COUNTIES WITH ITS PASSAGE...SIMILAR TO SATURDAY. WITH THE LACK OF STRATOCUMULUS THIS MORNING...ITS UNCLEAR EXACTLY HOW MUCH CUMULUS WILL DEVELOP LATER TODAY AS TEMPERATURES WARM INTO THE 70S. SUSPECT THERE WILL BE AT LEAST A SHALLOW...SOMEWHAT SCATTERED CUMULUS FIELD AHEAD OF THE SEA BREEZE SO WILL STICK WITH A PARTLY CLOUDY SKIES CHARACTER FOR TODAY. SKIES WILL LIKELY CLEAR A BIT IN THE WAKE OF THE SEA BREEZE AS MORE STABLE AIR IS DRAWN INLAND FROM OFF THE ATLANTIC. THIS MAY RESULT IN A PERIOD OF MOSTLY SUNNY TO SUNNY SKIES PRIOR TO SUNSET...MAINLY ACROSS THE COASTAL CORRIDORS. NO RAIN IS EXPECTED EVEN AS THE COASTAL FRONT DRAWS CLOSER TO THE COAST AND EVENTUALLY BECOMES ABSORBED IN THE BROADER SYNOPTIC FLOW. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... TONIGHT...THE AREA WILL REMAIN ALONG THE WESTERN FRINGES OF ATLANTIC HIGH PRESSURE TONIGHT. EXPECT MAINLY CLEAR SKIES TO DOMINATE WITH SOME PATCHY STRATOCUMULUS POSSIBLY MOVING INLAND FROM OFF THE ATLANTIC. THE BOUNDARY LAYER SHOULD DECOUPLE FOR MOST AREA AWAY FROM THE IMMEDIATE COAST A FEW HOURS AFTER SUNSET. GENERALLY FAVORED THE COOLER SIDE OF GUIDANCE GIVEN THE DECENT RADIATIONAL SETUP. LOWS WILL RANGE FROM THE LOWER 50S INLAND TO THE MID 50S ALONG THE IMMEDIATE COAST. A FEW UPPER 40S CAN NOT BE COMPLETELY RULED OUT...MAINLY IN THE NORMALLY COLDER LOCATIONS SUCH AS ALLENDALE AND JAMESTOWN. COULD SEE SOME SHALLOW GROUND FOG FORM AFTER MIDNIGHT...BUT ITS PROBABLY NOT WORTH MENTIONING GIVEN THE LACK OF ANY SIGNIFICANT IMPACT. MONDAY AND TUESDAY...THE FORECAST AREA WILL REMAIN ON THE PERIPHERY OF SURFACE HIGH PRESSURE IN THE ATLANTIC EARLY NEXT WEEK. THE UPPER LEVEL PATTERN WILL BECOME MORE AMPLIFIED BY TUESDAY...AS A DEEP TROUGH SHIFTS INTO THE CENTRAL PLAINS AND RIDGING STRENGTHENS ACROSS THE SOUTHEAST COAST. RISING HEIGHTS ALOFT AND SOUTH/SOUTHEAST FLOW WILL SUPPORT UNSEASONABLY WARM CONDITIONS EACH AFTERNOON. HIGH TEMPERATURES INLAND WILL RISE INTO THE UPPER 70S TO LOWER 80S ON MONDAY...WHILE WARMING SOLIDLY INTO THE LOWER 80S BY TUESDAY. THE ONSHORE COMPONENT TO THE SURFACE FLOW WILL KEEP COASTAL LOCATIONS NOTABLY COOLER...SUPPRESSING HIGH TEMPERATURES IN THE LOWER TO MID 70S NEAR THE BEACHES. ALTHOUGH LOW LEVEL MOISTURE WILL BE INCREASING...AND A SEABREEZE BOUNDARY WILL DEVELOP WITHIN MORE SUMMER-LIKE CONDITIONS...DECENT SUBSIDENCE SHOULD PREVENT DIURNAL SHOWER DEVELOPMENT. HAVE THUS CAPPED RAIN CHANCES BELOW 15 PERCENT. WEDNESDAY...DEEP LAYER RIDGING WILL GRADUALLY SHIFT FARTHER INTO THE ATLANTIC BY MID WEEK...WHILE THE ROBUST UPPER TROUGH STRETCHING FROM THE NORTHERN PLAINS TO THE SOUTHWEST STATES MAKES SOME PROGRESS EASTWARD. THIS SYSTEM WILL PROVIDE THE ENERGY TO SPAWN A SURFACE LOW AND TRAILING COLD FRONT TO THE WEST OF THE FORECAST AREA. THE GFS MODEL SOLUTIONS HAVE BEEN CONSISTENTLY MORE AGGRESSIVE IN BREAKING DOWN THE DEEP RIDGING...DECREASING SUBSIDENCE ENOUGH TO SUPPORT DIURNAL SHOWER DEVELOPMENT WEDNESDAY AFTERNOON. PREFER TO LEAN TOWARD A MORE CONSERVATIVE AND SLOWER SCENARIO...THUS CONTINUING TO KEEP RAIN CHANCES BELOW 15 PERCENT. WILL ALSO CONTINUE TO INDICATE UNSEASONABLY WARM HIGH TEMPERATURES...REACHING THE LOWER 80S AWAY FROM THE LOCALLY COOLER COASTLINE DURING THE AFTERNOON HOURS. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... MEDIUM RANGE MODEL SOLUTIONS MAINTAIN SIGNIFICANT DISCREPANCIES IN THE TIMING OF A COLD FRONT APPROACHING FROM THE WEST LATE IN THE WEEK. AN ELONGATED UPPER TROUGH OVER THE CENTRAL PLAINS WEDNESDAY NIGHT WILL BREAK INTO A MORE SPLIT FLOW FEATURE BY THURSDAY. SLOWER MODEL SOLUTIONS SUGGEST THE SOUTHERN SHORTWAVE ENERGY WILL SPIN UP A SECONDARY SURFACE LOW ALONG THE GULF COAST STATES THAT COULD DELAY THE PROGRESS OF THE FRONTAL SYSTEM. IN ADDITION...THERE IS SOME QUESTION AS TO THE RESILIENCY OF THE UPPER RIDGE AND SUBSEQUENT IMPACTS ON PRECIPITATION TIMING AND COVERAGE. UPON COLLABORATION WITH NEIGHBORING FORECAST OFFICES...PREFER TO LEAN TOWARD THE SLOWER MODELS SOLUTIONS AT THIS TIME. WILL INTRODUCE A SLIGHT CHANCE OF RAIN FROM WEST TO EAST AS EARLY AS THURSDAY...YET SUGGEST THE HIGHEST POTENTIAL FOR SHOWER/THUNDERSTORM COVERAGE FRIDAY AFTERNOON AND EVENING...WHEN THE SOUTHERN STREAM SHORTWAVE AND SURFACE LOW LIFT INTO THE AREA. REGARDLESS OF MODEL SOLUTION...THE UNSEASONABLY WARM CONDITIONS AHEAD OF THE FRONTAL SYSTEM WILL SUPPORT DECENT INSTABILITY AND SUBSEQUENT THUNDERSTORM DEVELOPMENT. THIS INSTABILITY...WHEN COMBINED WITH A POTENTIAL 40 TO 50 KT LOW LEVEL JET...COULD ALSO ALLOW THUNDERSTORMS TO BECOME STRONG AND ORGANIZED. HOWEVER...CONFIDENCE IN SUCH DETAILS THIS FAR OUT REMAINS LOW...ESPECIALLY CONSIDERING CURRENT MODEL CONSISTENCY ISSUES. EXPECT THE COLD FRONT TO HAVE CROSSED THE EAST COAST BY FRIDAY NIGHT...WITH SURFACE HIGH PRESSURE RAPIDLY REBUILDING FROM THE WEST IN ITS WAKE. HAVE MAINTAINED JUST A SLIGHT CHANCE FOR SHOWERS/THUNDERSTORMS INTO EARLY SATURDAY...WITH POPS FALLING BELOW 15 PERCENT FOR THE REMAINDER OF THE WEEKEND. HIGH TEMPERATURES WILL BE A FEW DEGREES COOLER FROM FRIDAY AFTERNOON THROUGH SUNDAY...BECOMING CLOSER TO SEASONAL NORMALS IN THE MID 70S BY THE WEEKEND. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... GENERALLY VFR. INCREASING MOISTURE FROM OFF THE ATLANTIC WILL LIKELY SUPPORT SOME STRATOCUMULUS THROUGH SUNRISE. ITS STILL UNCLEAR AT THIS POINT HOW WIDESPREAD THESE CLOUDS WILL BECOME BUT LATEST RAP DATA SUGGESTS ANY CIGS THAT ARE ESTABLISHED WILL LIKELY REMAIN LOW-END VFR...MAINLY AT KSAV WHERE THE RISK FOR LOW CLOUDS WILL BE THE GREATEST. WILL CARRY VFR CONDITIONS AT BOTH KCHS/KSAV FOR THE NEXT 24 HOURS. WILL LIKELY SEE A PERIOD OF GUSTY WINDS IN THE WAKE OF THE AFTERNOON...POSSIBLY REACHING AS HIGH AS 15-18 KT. EXTENDED AVIATION OUTLOOK...POSSIBLE FLIGHT RESTRICTIONS IN LIGHT FOG/MIST LATE AT NIGHT AND IN THE MORNING SUNDAY NIGHT THROUGH WEDNESDAY. && .MARINE... TODAY...NORTHEAST WINDS WILL GRADUALLY TURN SOUTHEAST TODAY AS THE COASTAL TROUGH DRIFTS CLOSER TO THE COAST AND GRADUALLY BECOMES ABSORBED IN THE BROADER SYNOPTIC FLOW. WINDS WILL GENERALLY REMAIN 10-15 KT THROUGH THE DAY...ALTHOUGH THERE WILL LIKELY BE COME ENHANCEMENT NEAR THE LAND/SEA INTERFACE AND IN THE CHARLESTON HARBOR AS THE SEA BREEZE DEVELOPS AND MOVES INLAND. SEAS WILL RANGE FROM 2-4 FT NEARSHORE WATERS WITH 4-5 FT OFFSHORE WATERS. TONIGHT...THERE ARE NO CONCERNS TONIGHT WITH SOUTHEAST WINDS DOMINATING. WINDS WILL REMAIN 10-15 KT WITH SEAS 2-4 FT... HIGHEST OVER THE GEORGIA OFFSHORE WATERS MONDAY THROUGH FRIDAY...THE MARINE ZONES WILL REMAIN ALONG THE WESTERN PERIPHERY OF A LARGE AND FAIRLY STRONG RIDGE OF ATLANTIC HIGH PRESSURE THROUGH THE UPCOMING WEEK. SOUTHEAST/SOUTH CIRCULATION AROUND THE HIGH WILL BECOME ENHANCED AT TIMES BY AFTERNOON/EVENING SEA BREEZE CIRCULATIONS...BUT EXPECT WINDS TO BE CAPPED AT 10 OR 15 KT. SEAS WILL GENERALLY RANGE FROM 2 TO 4 FT THROUGH MID WEEK. THE GRADIENT WILL LIKELY TIGHTEN BETWEEN THE ATLANTIC HIGH AND AN APPROACHING COLD FRONT BY THURSDAY. WINDS AND/OR SEAS COULD THEREFORE BUILD CLOSE TO ADVISORY LEVELS LATE IN THE FORECAST PERIOD. RIP CURRENTS...OPTED TO UPGRADE TO A MODERATE RISK FOR RIP CURRENTS FOR ALL BEACHES TODAY. WW4 OUTPUT SHOWS 8 TO OCCASIONAL 9 SECOND SWELLS DOMINATING FOR MUCH OF THE DAY. TYBEE ISLAND LIFEGUARDS REPORTED RIP CURRENTS ALONG WITH SEVERAL ASSISTS AND ONE RESCUE YESTERDAY AFTERNOON. CONSIDERING SIMILAR CONDITIONS WILL BE IN PLACE TODAY...THERE IS ENOUGH EVIDENCE TO SUPPORT A MODERATE RISK...DESPITE THE FAIRLY MODEST ONSHORE WIND REGIME. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR SCZ044-045- 052. MARINE...NONE. && $$ ST/79
AREA FORECAST DISCUSSION
NWS WICHITA KS
931 AM CDT SUN APR 7 2013 .UPDATE... ISSUED AT 922 AM CDT SUN APR 7 2013 PERSISTENT WARM AIR ADVECTION CONTINUES GENERATE BANDS OF VERY LIGHT RAIN ACROSS CENTRAL KANSAS. LOW LEVELS REMAIN SOMEWHAT DRY...THUS MOST PRECIPITATION EVAPORATING BEFORE REACHING THE GROUND. UPDATED FORECAST TO INCLUDE SLIGHT CHANCE POPS...THOUGH EXPECT MOST LOCATIONS TO REMAIN DRY. SUBSIDENCE BEHIND SHOWERS COMBINED WITH MIXING...PRODUCING A TEMPORARY BOOST AREAR OF RAIN BANDS. TIMING AND AMOUNT OF WARMING DIFFICULT TO FORECAST...AND ATTEMPTED TO EMULATE...WITH HRRR PROVIDING BEST GUIDANCE. SF && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 300 AM CDT SUN APR 7 2013 CURRENT SATELLITE WATER VAPOR IMAGERY SHOWS UPPER WAVE OVER NORTHERN NEVADA/SOUTHERN IDAHO RACING EASTWARD VIA ZONAL UPPER FLOW REGIME. THE ENVIRONMENT LOOKS CAPPED FOR SURFACE BASED ACTIVITY AND NOT SEEING ANY REAL GOOD LOW LEVEL CONVERGENCE...HOWEVER WARM AIR ADVECTION IN THE MID-LEVELS AHEAD OF APPROACHING PV WAVE SHOULD SPARK OFF SCATTERED ELEVATED SHOWERS/STORMS TODAY. ELEVATED INSTABILITY/SHEAR COMBO SUGGESTS A FEW STRONG STORMS TO POSSIBLY MARGINALLY SEVERE FOR THIS AFTERNOON/EVENING WITH HAIL BEING THE MAIN HAZARD. THIS ACTIVITY WILL MOVE NORTHEAST TONIGHT WITH A LULL IN THE ACTIVITY FOR MONDAY...AS SHORT WAVE RIDGING COMMENCES ALOFT. STILL THINK MODELS MIGHT BE A LITTLE OVER ZEALOUS ON QUALITY OF MOISTURE RETURN FOR MONDAY. GIVEN NO REAL LOW-LEVEL FOCUS AND STRONG CAPPING OVER THE REGION ON MONDAY WOULD EXPECT ANY AFTERNOON ACTIVITY TO DEVELOP OVER NORTHWEST KANSAS IN THE UPSLOPE REGIME. THE BETTER CHANCES OF THUNDERSTORMS FOR LATE MONDAY AFTERNOON/NIGHT WILL BE OVER CENTRAL KANSAS AND POINTS NORTH...AS LIFT AND MOISTURE TRANSPORT IS FAVORED NEAR WARM FRONT BOUNDARY. SEVERE WEATHER LOOKS MORE LIKELY ON TUESDAY AS MAIN UPPER WAVE MOVES TOWARDS THE CENTRAL PLAINS. THE MOST LIKELY MODE OF THUNDERSTORMS STILL SEEMS TO BE A LINE OF STRONG TO SEVERE THUNDERSTORMS MATERIALIZING TUESDAY AFTERNOON ALONG THE FRONT...AS DEEP MERIDIONAL TROUGHING AND STRONG UPPER DYNAMICS FAVOR LINEAR ACTIVITY. .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 300 AM CDT SUN APR 7 2013 LINGERING PRECIPITATION FOR WEDNESDAY WITH POSSIBLE RAIN/SNOW MIXTURE EARLY WEDNESDAY MORNING FOR CENTRAL KANSAS...FOLLOWED BY MUCH COOLER TEMPERATURES FOR WEDNESDAY/THURSDAY AND WARMER WEATHER TO RETURN FOR NEXT WEEKEND. JAKUB && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 646 AM CDT SUN APR 7 2013 DIFFICULT AVIATION FORECAST. NOT MUCH AGREEMENT BETWEEN MODELS WITH FINER DETAILS THAT WOULD SIGNIFICANTLY IMPACT AVIATION FORECASTS. SOME CHANCE FOR LIGHT PRECIPITATION AT KRSL/KSLN THIS MORNING FROM MID LEVEL CLOUD DECK. RAIN SHOWERS/THUNDERSTORMS ALSO POSSIBLE LATE THIS AFTERNOON/EVENING AT KICT/KHUT/KCNU...BUT UNCERTAINTY...TIMING AND COVERAGE PRECLUDE MENTIONING AT THIS TIME. MODELS ALL SHOW LOW LEVEL MOISTURE ON THE INCREASE DURING THE FORECAST...AND SUSPECT AT LEAST MVFR CEILINGS WILL BE LIKELY AT ALL SITES BY END OF THE VALID PERIOD...IF NOT IFR. -HOWERTON && .FIRE WEATHER... ISSUED AT 646 AM CDT SUN APR 7 2013 GRASSLAND FIRE DANGER INDEX MAY BRIEFLY GO INTO THE VERY HIGH CATEGORY ON TUESDAY AFTERNOON OVER PARTS OF CENTRAL AND SOUTH CENTRAL KANSAS. HOWEVER PRECIPITATION MAY LIMIT THIS THREAT. WINDS MAY BE GUSTY AT TIMES. CONFIDENCE IN FORECAST IS NOT PARTICULARLY HIGH DUE TO MODEL UNCERTAINTY. -HOWERTON && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 72 58 75 60 / 40 30 10 30 HUTCHINSON 72 56 75 59 / 40 30 10 40 NEWTON 71 56 74 59 / 60 40 10 40 ELDORADO 72 58 74 60 / 50 40 10 30 WINFIELD-KWLD 72 58 76 61 / 30 20 10 20 RUSSELL 71 53 74 55 / 50 30 40 60 GREAT BEND 72 55 75 56 / 40 30 30 50 SALINA 72 55 72 58 / 60 50 30 60 MCPHERSON 72 56 74 58 / 50 40 20 50 COFFEYVILLE 72 59 74 62 / 30 40 10 20 CHANUTE 72 58 72 60 / 50 60 10 20 IOLA 72 58 72 60 / 60 70 10 30 PARSONS-KPPF 72 59 73 61 / 30 40 10 20 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
716 AM CDT SUN APR 7 2013 .SHORT TERM...(TODAY) ISSUED AT 442 AM CDT SUN APR 7 2013 TODAY...DEEPER MOISTURE EXTENDING FROM SOUTHERN OK AND EAST TX WILL BE ADVECTED NORTHWARD AS A LEE SURFACE TROUGH DEEPENS ACROSS THE CENTRAL AND WESTERN HIGH PLAINS. THE SOUTHERLY LOW- LEVEL FLOW WILL ADVECT THIS DEEPER MOISTURE NORTHWARD ACROSS EASTERN KS LATE THIS AFTERNOON. THE WESTERN GULF OF MEXICO IS NOT AT EQUILIBRIUM EARLY THIS MORNING...BUT THE RESIDUAL MOISTURE RETURN SHOULD BE SUFFICIENT TO ALLOW MID TO UPPER 50 DEWPOINTS TO ADVECT NORTHWARD ACROSS THE CWA BY LATE AFTERNOON. MEANWHILE...A SHORTWAVE LENGTH H5 TROUGH WAS MOVING EASTWARD ACROSS CENTRAL CO...SOUTHWARD INTO NORTHWEST NM. THE NAM...ECMWF AND GFS SHOW THIS H5 TROUGH MOVING EAST ACROSS WESTERN AND CENTRAL KS TODAY. STRONGER ASCENT AHEAD OF THIS H5 TROUGH AND THE STRONGER ISENTROPIC LIFT ON THE NORTH SIDE OF DEEPER MOISTURE RETURN WILL ALLOW SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS TO DEVELOP FROM SOUTH TO NORTH ACROSS THE CWA DURING THE MID AND LATE AFTERNOON HOURS. THE VERTICAL WINDSHEAR LOOKS TO BE STRONG WITH 0-6KM SHEAR OF 40 TO 60 KTS ACROSS THE CWA THROUGH THE LATE AFTERNOON HOURS. INSTABILITY WILL INCREASE THROUGH THE AFTERNOON AS THE DEEPER MOISTURE ADVECTS NORTHWARD TO AT LEAST I-70. GIVEN STEEP LAPSE RATES FROM 700MB TO THE SURFACE...ONCE THE DEEPER MOISTURE ADVECT FAR ENOUGH NORTH WE SHOULD SEE SBCAPE INCREASE TO 1,000 TO 1,500 J/KG FROM I-70 SOUTH. THE NAM MODEL EVEN SHOWS AN ENHANCED BAND OF 0-1KM SRH OF 80-100 J/KG ALONG THE I-35 CORRIDOR BY 21Z AND LIFTING NORTHWARD TO I-70 BY 00Z. THIS WOULD BE SUFFICIENT FOR DISCRETE SUPERCELL TO POTENTIALLY PRODUCE ISOLATED TORNADOES. HOWEVER...THE MODE OF CONVECTION IS STILL IN QUESTION. THE ECMWF...GFS...AND NAM ALL SHOW NUMEROUS THUNDERSTORMS DEVELOPING ALONG I-35 AFTER 21Z AND EXTENDING WESTWARD TOWARDS ICT. IF A COMPLEX OR CLUSTER OF THUNDERSTORMS DEVELOPS LATE IN THE AFTERNOON HOURS ALONG THE NORTHERN EDGE OF DEEPER MOISTURE RETURN...THEN THE PRIMARY THREAT WILL LARGE HAIL AND SEVERE WIND GUSTS. THIS COMPLEX OF STORMS WILL DEVELOP NORTHWARD ACROSS EAST CENTRAL KS LATE IN THE AFTERNOON. IF THE THUNDERSTORMS REMAIN DISCRETE...THEN GIVEN THE 0-1KM SRH AND INSTABILITY...THEN ISOLATED TORNADOES COULD NOT BE RULED OUT FOR PORTIONS OF THE CWA...SOUTH OF I-70. THE RAP AND (ARW) WRF...TWO OF OUR MESOSCALE MODELS...SHOW THE INITIATION OF DEEP MOIST CONVECTION WEST AND SOUTHWEST OF THE CWA THROUGH THE LATE AFTERNOON HOURS. THE INITIAL MODE LOOKS DISCRETE WITH STORM MERGERS OCCURING AS THEY MOVE NORTHEAST ACROSS THE CWA DURING THE EARLY EVENING HOURS. STAY TUNED TO LATER UPDATES ON THE POTENTIAL FOR SEVERE WEATHER LATE THIS AFTERNOON AND EVENING. TEMPERATURES WILL WARM INTO THE LOWER TO MID 70S WITH PATCHES OF DENSE HIGH CLOUD COVER SPREADING ACROSS THE CWA THIS MORNING. CU SHOULD BEGIN TO DEVELOP AS THE DEEPER MOISTURE SURGES NORTHWARD THIS AFTERNOON. GARGAN .LONG TERM...(TONIGHT THROUGH SATURDAY) ISSUED AT 442 AM CDT SUN APR 7 2013 CONVECTIVE COMPLEX OF SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP/EXPAND EAST AND NORTHEAST ACROSS PRIMARILY THE SOUTHEAST HALF OF THE CWA THROUGH THE EARLY AND MID EVENING HOURS WITH A THREAT FOR PRIMARILY LARGE HAIL WITH THE STRONGER STORMS. HOWEVER...AS THE SHORTWAVE TROUGH MOVES THROUGH BY LATE EVENING...THE LLVL FLOW WILL BEGIN TO VEER AND ALLOW FOR SOME DRIER AIR TO ADVECT EASTWARD WHICH WILL FAVOR THE MORE EASTWARD PROGRESSION OF THE POSSIBLE MCS. HAVE THEREFORE TRENDED THE HIGHER POPS THROUGH THE EARLY/MID EVENING...THEN A GRADUAL DECREASED POP THROUGH LATE EVENING/MIDNIGHT...THEN A MUCH MORE RAPID DROP IN POPS AFTER MIDNIGHT WEST TO EAST ACROSS THE CWA. WILL KEEP THE SOUTHEAST CWA WARMER WITH THE CLOUDS AND HIGHER DEWPOINTS IN THE UPPER 50S WITH NEAR 50 IN THE FAR NORTH CENTRAL. ON MONDAY...OVERALL LACK OF LARGE SCALE ASCENT/FORCING WITHIN AN ENVIRONMENT EXHIBITING A RAPIDLY STRENGTHENING ELEVATED MIXED LAYER (EML) DOES NOT INCREASE CONFIDENCE IN CARRYING POPS BEYOND LOW END CHANCE CATEGORY. HAVE REMOVED POPS FOR MOST OF THE MORNING...BUT CARRIED LOW POPS IN THE LATE MORNING/AFTERNOON...ALTHOUGH IMPRESSIVE INHIBITION MAY WARRANT LOWERING/OR REMOVING POPS MORE. KEPT HIGHS IN THE LOW TO MID 70S DUE TO EXPECTED STRATUS DECK BENEATH INVERSION. BY MONDAY NIGHT...MORE CONVECTION IS EXPECTED TO ADVANCE/DEVELOP EASTWARD FROM WESTERN/CENTRAL KANSAS THROUGH THE NIGHT PRIMARILY ALONG THE NORTH OF THE WARM FRONT AS LLVL JET INCREASES THROUGH THE NIGHT. THE FOCUS FOR THIS HAS CONTINUES TO TREND NORTHWARD WITH TIME AND STRONG CAPPING OVER THE CWA MAY ALSO INHIBIT THE SOUTH AND EASTWARD EXTENT OF THE CONVECTION AS WELL. FOR NOW...HAVE KEPT LIKELY POPS ACROSS THE NORTHERN 2/3 OF THE CWA...BUT IF MODEL TRENDS CONTINUE...THE HIGHER POPS MAY NEED TO BE TRIMMED/SHIFTED MORE NORTHWARD CLOSER TO THE NE BORDER. TUESDAY AND TUESDAY NIGHT STILL APPEARS TO BE THE MOST ACTIVE TIMEFRAME FOR THIS STORM SYSTEM ACROSS OUR CWA AS A DEEPENING SFC LOW/COLD FRONT ADVANCES EASTWARD ACROSS THE AREA AS THE MAIN SHORTWAVE ROTATES NORTHEAST OUT OF THE LONGER WAVE TROUGH IN THE WEST INTO THE NORTHERN PLAINS EARLY WEDNESDAY. CONVECTION COULD FIRST INITIATE OVER CENTRAL KS THEN CONGEAL INTO A POSSIBLE SQUALL LINE AS IT MOVES EAST THROUGH THE AFTERNOON/EVENING WITH ALL MODES OF SEVERE WEATHER POSSIBLE DURING THIS TIME FRAME BEFORE THE FRONT USHERS IN COOLER AND DRIER AIR INTO EASTERN KS LATE IN THE NIGHT. WILL KEEP A LINGERING CHANCE FOR DECREASING CONVECTION/RAIN POTENTIAL ON WEDNESDAY WITH SHOWERS EXITING THE CWA WEDNESDAY NIGHT...THEN DRY THURSDAY INTO FRIDAY NIGHT. A SLIGHT CHANCE FOR SHOWERS WILL RETURN BY SATURDAY. AFTER HIGHS IN THE 60S/70S ON TUESDAY...WEDNESDAY TEMPS WILL COOL INTO THE 40S AND 50S FOR WEDNESDAY AND THURSDAY...THEN THE 50S FRIDAY AND THE 60S FOR SATURDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 711 AM CDT SUN APR 7 2013 EXPECT VFR CONDITIONS FOR THE NEXT 12 HOURS. THIS EVENING MVFR CEILINGS SHOULD DEVELOP ALONG WITH SHOWER AND THUNDERSTORMS. THUNDERSTORMS SHOULD MOVE EAST OF THE TAF SITES AFTER 6Z MON. THERE MAY BE SOME BRIEF LOW MVFR OR IFR CONDITIONS MAY OCCUR WITH THE STRONGER THUNDERSTORMS THIS EVENING. MVFR STRATUS WILL CONTINUE THROUGH 12Z MON. GARGAN && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GARGAN LONG TERM...63 AVIATION...GARGAN
AREA FORECAST DISCUSSION
NWS JACKSON KY
1052 AM EDT SUN APR 7 2013 .UPDATE... ISSUED AT 1027 AM EDT SUN APR 7 2013 TEMPERATURE RISE THIS MORNING HAS BEEN QUICKER THAN FORECAST...BUT AT THE SAME TIME CLOUDS ARE ALSO INCREASING QUICKER. HAVE ADJUSTED THE HOURLY TEMPERATURE FORECAST AND SKY COVER FORECAST TO ACCOUNT FOR THIS. INCREASING CLOUDS SHOULD KEEP CURRENT MAXIMUM TEMPERATURE FORECAST ON TARGET. ANOTHER ITEM TO ADDRESS FOR THIS UPDATE ARE DEWPOINTS AND POTENTIAL FIRE WEATHER CONCERNS. DEWPOINTS HAVE BEEN RESPONDING TO INCREASING SOUTHWEST FLOW...AND DESPITE RELATIVE HUMIDITY CURRENTLY IN THE 30 TO 40 PERCENT RANGE...WE SHOULD SEE RELATIVE HUMIDITY STAY ABOVE CRITICAL THRESHOLDS. THIS WILL BE MONITORED CLOSELY THOUGH AS WINDS ARE MUCH STRONGER THAN YESTERDAY. PLAN TO ISSUE AN SPS FOR ENHANCED WILD FIRE THREAT. FINALLY HAVE MADE SOME ADJUSTMENTS TO SHOWER CHANCES THIS AFTERNOON. LATEST HRRR POINTS TOWARDS DELAYING THE ONSET OF RAIN CHANCES AND ALSO EXTENDING THE CHANCE FURTHER SOUTH. HOWEVER THEN HRRR IS OVERPLAYING PRECIPITATION CHANCES THIS MORNING. HAVE FOLLOWED THE IDEA OF DELAYING PRECIPITATION CHANCES...BUT DID NOT EXTEND THE CHANCE FURTHER SOUTH. HAVE ACTUALLY LOWERED THE PROBABILITY FROM LIKELY TO CHANCE IN THE NORTH AS WELL. NDFD AND ZFP HAVE BEEN UPDATED. UPDATE ISSUED AT 658 AM EDT SUN APR 7 2013 FRONTAL BOUNDARY IS JUST ABOUT TO THE CINCINNATI METRO AREA WITH THE LINE OF SHOWERS PRETTY MUCH NON-EXISTENT AT THE TIME. HRRR IS ALSO DOWNPLAYING ACTIVITY ALONG THIS BOUNDARY THROUGH THE MORNING HOURS WHICH SEEMS VERY REASONABLE. STILL LOOKS LIKE WE COULD SEE AN UPTICK IN SHOWER OR THUNDERSTORM ACTIVITY THIS AFTERNOON AS INSTABILITY INCREASES JUST AHEAD OF THE STALLING BOUNDARY. MOST OF THE ACTIVITY MAY BE TIED TO WHETHER OR NOT WE CAN GET ENOUGH INSTABILITY. GIVEN DEWPOINTS MUCH LOWER THAN PREVIOUSLY ANTICIPATED...THIS COULD BE IN JEOPARDY. HOWEVER...WILL MAINTAIN THE CURRENT POPS AND LET DAYSHIFT RE-EVALUATE IF WE WILL SEE ANY SHOWER ACTIVITY IN THE FAR NORTH TODAY. DEWPOINTS ARE FINALLY STARTING TO CREEP UP A BIT...BUT REMAIN MUCH SLOWER THAN MODEL GUIDANCE. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 255 AM EDT SUN APR 7 2013 FAIRLY QUIET WEATHER EARLY THIS SUNDAY MORNING. A VIGOROUS SHORTWAVE IS PUSHING EAST ACROSS MICHIGAN THIS MORNING WITH A WEAK SURFACE BOUNDARY BEING DRAGGED ACROSS THE OHIO RIVER VALLEY. AT THE MOMENT...NOT MUCH ACTIVITY OUTSIDE OF A NARROW LINE OF BROKEN SHOWERS PUSHING EAST ACROSS NORTHERN INDIANA...BACK INTO SOUTHERN ILLINOIS. HRRR SEEMS TO HAVE A DECENT HANDLE ON THE RADAR TRENDS THIS MORNING. THE SHORTWAVE WILL EXIT TO THE EAST TODAY...WITH THE FRONTAL BOUNDARY STALLING ACROSS NORTHERN WEST VIRGINIA AND NORTHERN KENTUCKY. MODELS SEEM TO BE IN VERY GOOD AGREEMENT ON THIS PLACEMENT. THE BEST CHANCES FOR ANY RAIN WITH THIS FRONT WILL RESIDE ALONG THIS BOUNDARY...AND WILL LIKELY REMAIN ALONG AND NORTH OF I-64. MEANWHILE...DRY CONDITIONS WILL LIKELY PERSIST ACROSS THE REST OF EASTERN KENTUCKY. WITH MOISTURE RECOVERY VERY POOR AT BEST OVERNIGHT AND THE PROSPECTS OF DECENT MIXING TODAY...HAVE GONE WELL BELOW GUIDANCE WITH DEWPOINTS YET AGAIN TODAY. IN FACT...A FEW PLACES...ESPECIALLY IN SOUTHEAST KENTUCKY COULD SEE AFTERNOON RELATIVE HUMIDITIES FALL TO UNDER 30 PERCENT. WITH STRONGER SOUTHWEST WINDS TODAY...AHEAD OF THE FRONTAL BOUNDARY...THIS COULD CREATE A PERIOD OF DANGEROUS FIRE WEATHER CONDITIONS. THIS THREAT WILL HIGHLIGHTED IN THE HWO AND FIRE WEATHER PLANNING FORECAST. HIGHS TODAY WILL CLIMB EVEN HIGHER INTO THE LOW TO MID 70S...EXCEPT IN THE NORTH...WHERE CLOUDS AND PERHAPS PRECIPITATION MAY KEEP LOCATIONS IN THE 60S. FRONTAL BOUNDARY WILL SLOWLY DRIFT BACK TO THE NORTH THIS EVENING...WITH RAIN CHANCES DECREASING FROM SOUTH TO NORTH. SKIES SHOULD REMAIN MOSTLY TO PARTLY CLEAR OVERNIGHT...ALLOWING SOME VALLEY LOCATIONS TO DECOUPLE AND FALL BACK INTO THE 40S...WHILE RIDGES STAY IN THE 50S. ANOTHER VIGOROUS SHORTWAVE WILL TRACK NORTHEAST THROUGH THE PLAINS ON MONDAY...FURTHER PUSHING THE BOUNDARY TO THE NORTH AND KEEPING EASTERN KENTUCKY DOMINATED BY STRONG RIDGING. A VERY WARM DAY IS ON TAP WITH HIGHS SURGING WELL INTO THE 70S AREAWIDE. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 255 AM EDT SUN APR 7 2013 MODELS CONTINUE TO SHOW GENERAL AGREEMENT EARLY IN THE PERIOD IN TERMS OF HOW SYSTEMS WILL AFFECT OUR LOCAL WEATHER. PATTERN AMPLIFICATION WILL BE ONGOING...WITH A WESTERN CONUS UPPER TROUGH AND AND A SOUTHEAST CONUS UPPER RIDGE. STRONG SURFACE LOW PRESSURE WILL TRACK FROM CO AT THE START OF THE PERIOD TO THE VICINITY OF IL/IN BY THURSDAY MORNING. A FRONTAL BOUNDARY EXTENDING EAST FROM THE LOW WILL BE LAID OUT NORTH OF THE OHIO RIVER. MODELS DISAGREE ON EXACTLY HOW FAR NORTH/SOUTH IT WILL BE POSITIONED. THE ECMWF MANAGES TO BRING IT FURTHER SOUTH THAN ANY OTHER MODEL...MAKING IT INTO THE NORTHERN PART OF THE JKL FORECAST AREA BY 12Z THURSDAY. WITH ALL OTHER GUIDANCE SHOWING IT FURTHER NORTH...WILL GO WITH A FORECAST THAT KEEPS OUR AREA IN THE WARM SECTOR. A BROAD ZONE OF WARM AIR ADVECTION WILL BRING MOISTURE NORTH FROM THE GULF OF MEXICO AND LIFT IT ACROSS THE FRONT. THE BEST CHANCE OF RAIN WITH THIS WILL BE WELL TO OUR NORTH...BUT CAN NOT RULE OUT SOME SHOWERS MAKING IT INTO THE NORTHERN PART OF THE AREA. THE FORECAST BECOMES MORE PROBLEMATIC LATER IN THE WEEK DUE TO CONTINUED DIFFERENCES IN MODEL TIMING OF THE SURFACE LOW AND ITS TRAILING COLD FRONT. THE ECMWF IS THE SLOWEST...WITH LOCAL FROPA NOT HAPPENING UNTIL FRIDAY AFTERNOON. THE END OF THE NAM RUN ON WED MORNING LOOKS SIMILAR TO THE GFS...WHICH ENDS UP WITH FROPA DURING THE DAY THURSDAY. THERE ARE SOME MEMBERS OF THE GFS ENSEMBLE WHICH SHOW SIMILAR TIMING AS THE ECMWF...BUT THE GFS ENSEMBLE MEAN IS MORE SUPPORTIVE OF THE OPERATIONAL GFS. WILL FAVOR A COMPROMISE SOLUTION CLOSER TO THE GFS. WITH THAT SAID...HIGHEST POPS...IN LIKELY CATEGORY...WILL BE ON THURSDAY AND THURSDAY NIGHT. WILL USE HIGH CHANCE ON FRIDAY TO LEND SOME CREDENCE TO THE ECMWF. ALL MODELS SHOW INSTABILITY AHEAD OF THE COLD FRONT...AND A CHANCE OF THUNDER WILL BE USED WITH THE APPROACH AND PASSAGE OF THE COLD FRONT. WINDS ALOFT LOOK TO BE QUITE STRONG...AND WOULD SUPPORT SEVERE WX. HOWEVER...THE DEGREE OF INSTABILITY DOES NOT REALLY STAND OUT. THE SET-UP WILL NEED TO CONTINUE TO BE WATCHED. THE WARMEST AIR MASS OF THE SEASON SO FAR WILL BE IN PLACE UP UNTIL COLD FROPA. NEEDLESS TO SAY...FRONTAL TIMING WILL PLAY A KEY ROLE IN TEMPS LATE IN THE PERIOD...AND LEADS TO A LOWER CONFIDENCE IN THE TEMPERATURE FORECAST FOR THURSDAY INTO FRIDAY...AND A POTENTIAL FOR MORE SIZEABLE ERRORS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 658 AM EDT SUN APR 7 2013 VFR CONDITIONS WILL HOLD ON THROUGH THE PERIOD. AN APPROACHING COLD FRONT WILL MOVE INTO NORTHERN KENTUCKY TODAY. SOME SCATTERED SHOWERS AND A FEW THUNDERSTORMS ARE POSSIBLE...MAINLY NORTH OF I-64. LOWER CLOUDS AND PRECIPITATION WILL NOT LIKELY MAKE IT SOUTH OF I-64...KEEPING THE TAF SITES DRY WITH JUST SOME HIGH CLOUDS TO CONTEND WITH. && .FIRE WEATHER... ISSUED AT 1051 AM EDT SUN APR 7 2013 DEWPOINTS HAVE BEEN RISING IN THE INCREASING SOUTHWEST FLOW...AND DESPITE RELATIVE HUMIDITY CURRENTLY IN THE 30 TO 40 PERCENT RANGE OVER SOUTHEAST KY...WE SHOULD SEE RELATIVE HUMIDITY STAY ABOVE CRITICAL THRESHOLDS. HOWEVER SOME SPOTS WILL BE NEAR 25 PERCENT RH THIS AFTERNOON. THIS WILL BE MONITORED CLOSELY AS WINDS ARE MUCH STRONGER THAN YESTERDAY...WITH GUSTS TO 30 MPH EXPECTED FOR THIS AFTERNOON. HAVE ISSUED AN SPS FOR ENHANCED WILD FIRE THREAT. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SBH SHORT TERM...KAS LONG TERM...HAL AVIATION...KAS FIRE WEATHER...SBH
AREA FORECAST DISCUSSION
NWS JACKSON KY
1028 AM EDT SUN APR 7 2013 .UPDATE... ISSUED AT 1027 AM EDT SUN APR 7 2013 TEMPERATURE RISE THIS MORNING HAS BEEN QUICKER THAN FORECAST...BUT AT THE SAME TIME CLOUDS ARE ALSO INCREASING QUICKER. HAVE ADJUSTED THE HOURLY TEMPERATURE FORECAST AND SKY COVER FORECAST TO ACCOUNT FOR THIS. INCREASING CLOUDS SHOULD KEEP CURRENT MAXIMUM TEMPERATURE FORECAST ON TARGET. ANOTHER ITEM TO ADDRESS FOR THIS UPDATE ARE DEWPOINTS AND POTENTIAL FIRE WEATHER CONCERNS. DEWPOINTS HAVE BEEN RESPONDING TO INCREASING SOUTHWEST FLOW...AND DESPITE RELATIVE HUMIDITY CURRENTLY IN THE 30 TO 40 PERCENT RANGE...WE SHOULD SEE RELATIVE HUMIDITY STAY ABOVE CRITICAL THRESHOLDS. THIS WILL BE MONITORED CLOSELY THOUGH AS WINDS ARE MUCH STRONGER THAN YESTERDAY. PLAN TO ISSUE AN SPS FOR ENHANCED WILD FIRE THREAT. FINALLY HAVE MADE SOME ADJUSTMENTS TO SHOWER CHANCES THIS AFTERNOON. LATEST HRRR POINTS TOWARDS DELAYING THE ONSET OF RAIN CHANCES AND ALSO EXTENDING THE CHANCE FURTHER SOUTH. HOWEVER THEN HRRR IS OVERPLAYING PRECIPITATION CHANCES THIS MORNING. HAVE FOLLOWED THE IDEA OF DELAYING PRECIPITATION CHANCES...BUT DID NOT EXTEND THE CHANCE FURTHER SOUTH. HAVE ACTUALLY LOWERED THE PROBABILITY FROM LIKELY TO CHANCE IN THE NORTH AS WELL. NDFD AND ZFP HAVE BEEN UPDATED. UPDATE ISSUED AT 658 AM EDT SUN APR 7 2013 FRONTAL BOUNDARY IS JUST ABOUT TO THE CINCINNATI METRO AREA WITH THE LINE OF SHOWERS PRETTY MUCH NON-EXISTENT AT THE TIME. HRRR IS ALSO DOWNPLAYING ACTIVITY ALONG THIS BOUNDARY THROUGH THE MORNING HOURS WHICH SEEMS VERY REASONABLE. STILL LOOKS LIKE WE COULD SEE AN UPTICK IN SHOWER OR THUNDERSTORM ACTIVITY THIS AFTERNOON AS INSTABILITY INCREASES JUST AHEAD OF THE STALLING BOUNDARY. MOST OF THE ACTIVITY MAY BE TIED TO WHETHER OR NOT WE CAN GET ENOUGH INSTABILITY. GIVEN DEWPOINTS MUCH LOWER THAN PREVIOUSLY ANTICIPATED...THIS COULD BE IN JEOPARDY. HOWEVER...WILL MAINTAIN THE CURRENT POPS AND LET DAYSHIFT RE-EVALUATE IF WE WILL SEE ANY SHOWER ACTIVITY IN THE FAR NORTH TODAY. DEWPOINTS ARE FINALLY STARTING TO CREEP UP A BIT...BUT REMAIN MUCH SLOWER THAN MODEL GUIDANCE. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 255 AM EDT SUN APR 7 2013 FAIRLY QUIET WEATHER EARLY THIS SUNDAY MORNING. A VIGOROUS SHORTWAVE IS PUSHING EAST ACROSS MICHIGAN THIS MORNING WITH A WEAK SURFACE BOUNDARY BEING DRAGGED ACROSS THE OHIO RIVER VALLEY. AT THE MOMENT...NOT MUCH ACTIVITY OUTSIDE OF A NARROW LINE OF BROKEN SHOWERS PUSHING EAST ACROSS NORTHERN INDIANA...BACK INTO SOUTHERN ILLINOIS. HRRR SEEMS TO HAVE A DECENT HANDLE ON THE RADAR TRENDS THIS MORNING. THE SHORTWAVE WILL EXIT TO THE EAST TODAY...WITH THE FRONTAL BOUNDARY STALLING ACROSS NORTHERN WEST VIRGINIA AND NORTHERN KENTUCKY. MODELS SEEM TO BE IN VERY GOOD AGREEMENT ON THIS PLACEMENT. THE BEST CHANCES FOR ANY RAIN WITH THIS FRONT WILL RESIDE ALONG THIS BOUNDARY...AND WILL LIKELY REMAIN ALONG AND NORTH OF I-64. MEANWHILE...DRY CONDITIONS WILL LIKELY PERSIST ACROSS THE REST OF EASTERN KENTUCKY. WITH MOISTURE RECOVERY VERY POOR AT BEST OVERNIGHT AND THE PROSPECTS OF DECENT MIXING TODAY...HAVE GONE WELL BELOW GUIDANCE WITH DEWPOINTS YET AGAIN TODAY. IN FACT...A FEW PLACES...ESPECIALLY IN SOUTHEAST KENTUCKY COULD SEE AFTERNOON RELATIVE HUMIDITIES FALL TO UNDER 30 PERCENT. WITH STRONGER SOUTHWEST WINDS TODAY...AHEAD OF THE FRONTAL BOUNDARY...THIS COULD CREATE A PERIOD OF DANGEROUS FIRE WEATHER CONDITIONS. THIS THREAT WILL HIGHLIGHTED IN THE HWO AND FIRE WEATHER PLANNING FORECAST. HIGHS TODAY WILL CLIMB EVEN HIGHER INTO THE LOW TO MID 70S...EXCEPT IN THE NORTH...WHERE CLOUDS AND PERHAPS PRECIPITATION MAY KEEP LOCATIONS IN THE 60S. FRONTAL BOUNDARY WILL SLOWLY DRIFT BACK TO THE NORTH THIS EVENING...WITH RAIN CHANCES DECREASING FROM SOUTH TO NORTH. SKIES SHOULD REMAIN MOSTLY TO PARTLY CLEAR OVERNIGHT...ALLOWING SOME VALLEY LOCATIONS TO DECOUPLE AND FALL BACK INTO THE 40S...WHILE RIDGES STAY IN THE 50S. ANOTHER VIGOROUS SHORTWAVE WILL TRACK NORTHEAST THROUGH THE PLAINS ON MONDAY...FURTHER PUSHING THE BOUNDARY TO THE NORTH AND KEEPING EASTERN KENTUCKY DOMINATED BY STRONG RIDGING. A VERY WARM DAY IS ON TAP WITH HIGHS SURGING WELL INTO THE 70S AREAWIDE. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 255 AM EDT SUN APR 7 2013 MODELS CONTINUE TO SHOW GENERAL AGREEMENT EARLY IN THE PERIOD IN TERMS OF HOW SYSTEMS WILL AFFECT OUR LOCAL WEATHER. PATTERN AMPLIFICATION WILL BE ONGOING...WITH A WESTERN CONUS UPPER TROUGH AND AND A SOUTHEAST CONUS UPPER RIDGE. STRONG SURFACE LOW PRESSURE WILL TRACK FROM CO AT THE START OF THE PERIOD TO THE VICINITY OF IL/IN BY THURSDAY MORNING. A FRONTAL BOUNDARY EXTENDING EAST FROM THE LOW WILL BE LAID OUT NORTH OF THE OHIO RIVER. MODELS DISAGREE ON EXACTLY HOW FAR NORTH/SOUTH IT WILL BE POSITIONED. THE ECMWF MANAGES TO BRING IT FURTHER SOUTH THAN ANY OTHER MODEL...MAKING IT INTO THE NORTHERN PART OF THE JKL FORECAST AREA BY 12Z THURSDAY. WITH ALL OTHER GUIDANCE SHOWING IT FURTHER NORTH...WILL GO WITH A FORECAST THAT KEEPS OUR AREA IN THE WARM SECTOR. A BROAD ZONE OF WARM AIR ADVECTION WILL BRING MOISTURE NORTH FROM THE GULF OF MEXICO AND LIFT IT ACROSS THE FRONT. THE BEST CHANCE OF RAIN WITH THIS WILL BE WELL TO OUR NORTH...BUT CAN NOT RULE OUT SOME SHOWERS MAKING IT INTO THE NORTHERN PART OF THE AREA. THE FORECAST BECOMES MORE PROBLEMATIC LATER IN THE WEEK DUE TO CONTINUED DIFFERENCES IN MODEL TIMING OF THE SURFACE LOW AND ITS TRAILING COLD FRONT. THE ECMWF IS THE SLOWEST...WITH LOCAL FROPA NOT HAPPENING UNTIL FRIDAY AFTERNOON. THE END OF THE NAM RUN ON WED MORNING LOOKS SIMILAR TO THE GFS...WHICH ENDS UP WITH FROPA DURING THE DAY THURSDAY. THERE ARE SOME MEMBERS OF THE GFS ENSEMBLE WHICH SHOW SIMILAR TIMING AS THE ECMWF...BUT THE GFS ENSEMBLE MEAN IS MORE SUPPORTIVE OF THE OPERATIONAL GFS. WILL FAVOR A COMPROMISE SOLUTION CLOSER TO THE GFS. WITH THAT SAID...HIGHEST POPS...IN LIKELY CATEGORY...WILL BE ON THURSDAY AND THURSDAY NIGHT. WILL USE HIGH CHANCE ON FRIDAY TO LEND SOME CREDENCE TO THE ECMWF. ALL MODELS SHOW INSTABILITY AHEAD OF THE COLD FRONT...AND A CHANCE OF THUNDER WILL BE USED WITH THE APPROACH AND PASSAGE OF THE COLD FRONT. WINDS ALOFT LOOK TO BE QUITE STRONG...AND WOULD SUPPORT SEVERE WX. HOWEVER...THE DEGREE OF INSTABILITY DOES NOT REALLY STAND OUT. THE SET-UP WILL NEED TO CONTINUE TO BE WATCHED. THE WARMEST AIR MASS OF THE SEASON SO FAR WILL BE IN PLACE UP UNTIL COLD FROPA. NEEDLESS TO SAY...FRONTAL TIMING WILL PLAY A KEY ROLE IN TEMPS LATE IN THE PERIOD...AND LEADS TO A LOWER CONFIDENCE IN THE TEMPERATURE FORECAST FOR THURSDAY INTO FRIDAY...AND A POTENTIAL FOR MORE SIZEABLE ERRORS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 658 AM EDT SUN APR 7 2013 VFR CONDITIONS WILL HOLD ON THROUGH THE PERIOD. AN APPROACHING COLD FRONT WILL MOVE INTO NORTHERN KENTUCKY TODAY. SOME SCATTERED SHOWERS AND A FEW THUNDERSTORMS ARE POSSIBLE...MAINLY NORTH OF I-64. LOWER CLOUDS AND PRECIPITATION WILL NOT LIKELY MAKE IT SOUTH OF I-64...KEEPING THE TAF SITES DRY WITH JUST SOME HIGH CLOUDS TO CONTEND WITH. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SBH SHORT TERM...KAS LONG TERM...HAL AVIATION...KAS
AREA FORECAST DISCUSSION
NWS JACKSON KY
658 AM EDT SUN APR 7 2013 .UPDATE... ISSUED AT 658 AM EDT SUN APR 7 2013 FRONTAL BOUNDARY IS JUST ABOUT TO THE CINCINNATI METRO AREA WITH THE LINE OF SHOWERS PRETTY MUCH NON-EXISTENT AT THE TIME. HRRR IS ALSO DOWNPLAYING ACTIVITY ALONG THIS BOUNDARY THROUGH THE MORNING HOURS WHICH SEEMS VERY REASONABLE. STILL LOOKS LIKE WE COULD SEE AN UPTICK IN SHOWER OR THUNDERSTORM ACTIVITY THIS AFTERNOON AS INSTABILITY INCREASES JUST AHEAD OF THE STALLING BOUNDARY. MOST OF THE ACTIVITY MAY BE TIED TO WHETHER OR NOT WE CAN GET ENOUGH INSTABILITY. GIVEN DEWPOINTS MUCH LOWER THAN PREVIOUSLY ANTICIPATED...THIS COULD BE IN JEOPARDY. HOWEVER...WILL MAINTAIN THE CURRENT POPS AND LET DAYSHIFT RE-EVALUATE IF WE WILL SEE ANY SHOWER ACTIVITY IN THE FAR NORTH TODAY. DEWPOINTS ARE FINALLY STARTING TO CREEP UP A BIT...BUT REMAIN MUCH SLOWER THAN MODEL GUIDANCE. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 255 AM EDT SUN APR 7 2013 FAIRLY QUIET WEATHER EARLY THIS SUNDAY MORNING. A VIGOROUS SHORTWAVE IS PUSHING EAST ACROSS MICHIGAN THIS MORNING WITH A WEAK SURFACE BOUNDARY BEING DRAGGED ACROSS THE OHIO RIVER VALLEY. AT THE MOMENT...NOT MUCH ACTIVITY OUTSIDE OF A NARROW LINE OF BROKEN SHOWERS PUSHING EAST ACROSS NORTHERN INDIANA...BACK INTO SOUTHERN ILLINOIS. HRRR SEEMS TO HAVE A DECENT HANDLE ON THE RADAR TRENDS THIS MORNING. THE SHORTWAVE WILL EXIT TO THE EAST TODAY...WITH THE FRONTAL BOUNDARY STALLING ACROSS NORTHERN WEST VIRGINIA AND NORTHERN KENTUCKY. MODELS SEEM TO BE IN VERY GOOD AGREEMENT ON THIS PLACEMENT. THE BEST CHANCES FOR ANY RAIN WITH THIS FRONT WILL RESIDE ALONG THIS BOUNDARY...AND WILL LIKELY REMAIN ALONG AND NORTH OF I-64. MEANWHILE...DRY CONDITIONS WILL LIKELY PERSIST ACROSS THE REST OF EASTERN KENTUCKY. WITH MOISTURE RECOVERY VERY POOR AT BEST OVERNIGHT AND THE PROSPECTS OF DECENT MIXING TODAY...HAVE GONE WELL BELOW GUIDANCE WITH DEWPOINTS YET AGAIN TODAY. IN FACT...A FEW PLACES...ESPECIALLY IN SOUTHEAST KENTUCKY COULD SEE AFTERNOON RELATIVE HUMIDITIES FALL TO UNDER 30 PERCENT. WITH STRONGER SOUTHWEST WINDS TODAY...AHEAD OF THE FRONTAL BOUNDARY...THIS COULD CREATE A PERIOD OF DANGEROUS FIRE WEATHER CONDITIONS. THIS THREAT WILL HIGHLIGHTED IN THE HWO AND FIRE WEATHER PLANNING FORECAST. HIGHS TODAY WILL CLIMB EVEN HIGHER INTO THE LOW TO MID 70S...EXCEPT IN THE NORTH...WHERE CLOUDS AND PERHAPS PRECIPITATION MAY KEEP LOCATIONS IN THE 60S. FRONTAL BOUNDARY WILL SLOWLY DRIFT BACK TO THE NORTH THIS EVENING...WITH RAIN CHANCES DECREASING FROM SOUTH TO NORTH. SKIES SHOULD REMAIN MOSTLY TO PARTLY CLEAR OVERNIGHT...ALLOWING SOME VALLEY LOCATIONS TO DECOUPLE AND FALL BACK INTO THE 40S...WHILE RIDGES STAY IN THE 50S. ANOTHER VIGOROUS SHORTWAVE WILL TRACK NORTHEAST THROUGH THE PLAINS ON MONDAY...FURTHER PUSHING THE BOUNDARY TO THE NORTH AND KEEPING EASTERN KENTUCKY DOMINATED BY STRONG RIDGING. A VERY WARM DAY IS ON TAP WITH HIGHS SURGING WELL INTO THE 70S AREAWIDE. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 255 AM EDT SUN APR 7 2013 MODELS CONTINUE TO SHOW GENERAL AGREEMENT EARLY IN THE PERIOD IN TERMS OF HOW SYSTEMS WILL AFFECT OUR LOCAL WEATHER. PATTERN AMPLIFICATION WILL BE ONGOING...WITH A WESTERN CONUS UPPER TROUGH AND AND A SOUTHEAST CONUS UPPER RIDGE. STRONG SURFACE LOW PRESSURE WILL TRACK FROM CO AT THE START OF THE PERIOD TO THE VICINITY OF IL/IN BY THURSDAY MORNING. A FRONTAL BOUNDARY EXTENDING EAST FROM THE LOW WILL BE LAID OUT NORTH OF THE OHIO RIVER. MODELS DISAGREE ON EXACTLY HOW FAR NORTH/SOUTH IT WILL BE POSITIONED. THE ECMWF MANAGES TO BRING IT FURTHER SOUTH THAN ANY OTHER MODEL...MAKING IT INTO THE NORTHERN PART OF THE JKL FORECAST AREA BY 12Z THURSDAY. WITH ALL OTHER GUIDANCE SHOWING IT FURTHER NORTH...WILL GO WITH A FORECAST THAT KEEPS OUR AREA IN THE WARM SECTOR. A BROAD ZONE OF WARM AIR ADVECTION WILL BRING MOISTURE NORTH FROM THE GULF OF MEXICO AND LIFT IT ACROSS THE FRONT. THE BEST CHANCE OF RAIN WITH THIS WILL BE WELL TO OUR NORTH...BUT CAN NOT RULE OUT SOME SHOWERS MAKING IT INTO THE NORTHERN PART OF THE AREA. THE FORECAST BECOMES MORE PROBLEMATIC LATER IN THE WEEK DUE TO CONTINUED DIFFERENCES IN MODEL TIMING OF THE SURFACE LOW AND ITS TRAILING COLD FRONT. THE ECMWF IS THE SLOWEST...WITH LOCAL FROPA NOT HAPPENING UNTIL FRIDAY AFTERNOON. THE END OF THE NAM RUN ON WED MORNING LOOKS SIMILAR TO THE GFS...WHICH ENDS UP WITH FROPA DURING THE DAY THURSDAY. THERE ARE SOME MEMBERS OF THE GFS ENSEMBLE WHICH SHOW SIMILAR TIMING AS THE ECMWF...BUT THE GFS ENSEMBLE MEAN IS MORE SUPPORTIVE OF THE OPERATIONAL GFS. WILL FAVOR A COMPROMISE SOLUTION CLOSER TO THE GFS. WITH THAT SAID...HIGHEST POPS...IN LIKELY CATEGORY...WILL BE ON THURSDAY AND THURSDAY NIGHT. WILL USE HIGH CHANCE ON FRIDAY TO LEND SOME CREDENCE TO THE ECMWF. ALL MODELS SHOW INSTABILITY AHEAD OF THE COLD FRONT...AND A CHANCE OF THUNDER WILL BE USED WITH THE APPROACH AND PASSAGE OF THE COLD FRONT. WINDS ALOFT LOOK TO BE QUITE STRONG...AND WOULD SUPPORT SEVERE WX. HOWEVER...THE DEGREE OF INSTABILITY DOES NOT REALLY STAND OUT. THE SET-UP WILL NEED TO CONTINUE TO BE WATCHED. THE WARMEST AIR MASS OF THE SEASON SO FAR WILL BE IN PLACE UP UNTIL COLD FROPA. NEEDLESS TO SAY...FRONTAL TIMING WILL PLAY A KEY ROLE IN TEMPS LATE IN THE PERIOD...AND LEADS TO A LOWER CONFIDENCE IN THE TEMPERATURE FORECAST FOR THURSDAY INTO FRIDAY...AND A POTENTIAL FOR MORE SIZEABLE ERRORS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 658 AM EDT SUN APR 7 2013 VFR CONDITIONS WILL HOLD ON THROUGH THE PERIOD. AN APPROACHING COLD FRONT WILL MOVE INTO NORTHERN KENTUCKY TODAY. SOME SCATTERED SHOWERS AND A FEW THUNDERSTORMS ARE POSSIBLE...MAINLY NORTH OF I-64. LOWER CLOUDS AND PRECIPITATION WILL NOT LIKELY MAKE IT SOUTH OF I-64...KEEPING THE TAF SITES DRY WITH JUST SOME HIGH CLOUDS TO CONTEND WITH. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KAS SHORT TERM...KAS LONG TERM...HAL AVIATION...KAS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1029 AM EDT SUN APR 7 2013 .SYNOPSIS... RAIN CHANCES WILL INCREASE TODAY AS A COLD FRONT SLIDES OVER THE REGION. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WHAT A DIFFERENCE 24 HOURS MAKES...SPRING HAS SEEMINGLY SPRUNG OVER THE UPPER OHIO VALLEY. TEMPERATURES THIS MORNING HAVE ALREADY SKYROCKETED INTO THE MID 60S AS PRE-FRONTAL MIXING COMBINED WITH THE BONE DRY BOUNDARY LAYER HAS ALLOWED FOR 850 MB TEMPERATURES TO MIX OUT EARLY TODAY. AS A RESULT...HIGH TEMPERATURES HAVE BEEN RAISED ACROSS THE BOARD FOR THE AFTERNOON. THE AFOREMENTIONED FRONTAL BOUNDARY HAS DEFINITELY FELT THE PINCH FROM THE DRY BOUNDARY LAYER...AND IS HARDLY DISCERNIBLE ON THE REGIONAL RADAR MOSAIC. AT THE MOMENT...ONLY A FEW ISOLATED SHOWERS ARE NOTED ALONG THE BOUNDARY FROM CENTRAL OHIO TO NORTHWESTERN PENNSYLVANIA. AS THE DAY CONTINUES...IT WOULD SEEM THIS SHOULD INCREASE A BIT WITH DIURNAL INSTABILITY ADDED TO THE PICTURE. HOWEVER...GIVEN THE DRY ENVIRONMENT...SIGNIFICANT RAINFALL ALONG THE FRONT SEEMS INCREASINGLY UNLIKELY. AS A RESULT...QPF AND POPS WERE CUT FOR THE AFTERNOON HOURS. AREAS SOUTHEAST OF PITTSBURGH STILL STAND THE BEST SHOT AT SEEING SHOWERS THIS AFTERNOON...HOWEVER WHATEVER DOES DEVELOP IS LIKELY TO BE QUITE LIGHT. FRIES && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... MODEL CONSENSUS FAVORS A STALLING OF THE FRONT ACROSS NORTHERN WEST VIRGINIA SUNDAY NIGHT BEFORE IT TURNS NORTHWARD AS A WARM FRONT ON MONDAY. POPS FOR SHOWERS WERE CONTINUED THROUGH MONDAY NIGHT BEFORE BEING INCREASED AGAIN ON TUESDAY. KEPT THUNDER MONDAY AFTERNOON/EVENING AS THE HIGHER CAPE SUGGESTS. WHILE AGREEMENT ON THE PLACEMENT OF THE FRONT BY TUESDAY BECOMES LESS PRONOUNCED...THE ECMWF/GFS/NAM ALL LIKE THE IDEA OF TRACKING A SHRTWV ALONG THE BNDRY BY THE AFTERNOON HOURS. THIS WOULD INCRS LIFT AND SHEAR ALONG THE FRONTAL ZONE. THESE INGREDIENTS WITH SOME WEAK INSTABILITY MAY BE SUFFICIENT TO OVERCOME A MODERATELY STRONG CAP ALONG THE BOUNDARY. THUS...A MENTION OF THUNDERSTORMS WAS ADDED. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... OVERALL...CONFIDENCE IN EXTENDED FORECAST IS LOWER THAN NORMAL...SIMILAR TO YESTERDAY. FRONT WILL STILL BE HUNG UP TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...PROBABLY TO THE NORTH OF THE REGION. ALTHOUGH COLD FRONT WILL LIKELY BEGIN TO CROSS THE REGION ON THURSDAY...GFS/ECMWF CANNOT DECIDE WHETHER THE COLD FRONT WILL TAKE 24 OR 48 HOURS TO PUSH ALL THE WAY THROUGH. HAVE BUMPED UP POPS TO LIKELY THURSDAY NIGHT...BUT OTHERWISE MADE LITTLE CHANGES TO POPS OR TEMPERATURES. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... VFR CONDITIONS WL CONTINUE THIS MRNG ALTHOUGH BROAD SWATH OF MID LVL CLDINESS CONTS TO FLOW OVR THE UPR OH VALLEY REGION. STRONG LOW PRES CROSSING THE GREAT LAKES WL DRAG A WEAK FRONT ACRS AREA PORTS TODAY. GIVEN THE INITIALLY PALTRY BNDRY LAYER MSTR SUPPLY AND EXPECTED EWD PROGRESS OF THE SPPRTG SHRTWV...FORECAST WL FEATURE -SHRA WITH HIGH BASED CIGS AND VEERED WIND...GUSTS OF WHICH MAY APPRCH 30 KT SHOULD NAM AND RAP MOMENTUM TRANSFER PROGNOSIS BE REALIZED. CONFIDENCE IN MORE SIGNIFICANT OR WIDESPREAD DETERIORATION IS NOT SUFFICIENT TO WARRANT TAF MENTION JUST YET. .OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/... THE BOUNDARY SHOULD SHIFT SOUTH OF THE REGION TONIGHT...THEN BE PULLED NORTHWARD ONCE AGAIN ON MONDAY AS LOW PRES DIGS ACRS THE GREAT LAKES. FRONT POSITIONING IS QUESTIONABLE THROUGH MUCH OF THE WEEK...SO OCCASIONAL RESTRICTIONS SHOULD BE ANTICIPATED. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
618 AM EDT SUN APR 7 2013 .SYNOPSIS... RAIN CHANCES WILL INCREASE TODAY AS A COLD FRONT SLIDES OVER THE REGION. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... TEMPERATURE TREND THIS MORNING IS A BIT WARMER THAN PREVIOUS FCST...SO MADE SOME UPWARD ADJUSTMENT TO HOURLY NUMBERS. ALSO ADJUSTED DEW POINTS DOWN...ALSO BASED ON LATEST TRENDS. HIGH TEMPS WERE FORECAST USING WARMER NAM GUIDANCE. MAINTAINED WIND GUSTS NR 30 KTS GIVEN MOMENTUM TRANSFER FORECAST OF NAM AND RAP MDLS. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... MODEL CONSENSUS FAVORS A STALLING OF THE FRONT ACROSS NORTHERN WEST VIRGINIA SUNDAY NIGHT BEFORE IT TURNS NORTHWARD AS A WARM FRONT ON MONDAY. POPS FOR SHOWERS WERE CONTINUED THROUGH MONDAY NIGHT BEFORE BEING INCREASED AGAIN ON TUESDAY. KEPT THUNDER MONDAY AFTERNOON/EVENING AS THE HIGHER CAPE SUGGESTS. WHILE AGREEMENT ON THE PLACEMENT OF THE FRONT BY TUESDAY BECOMES LESS PRONOUNCED...THE ECMWF/GFS/NAM ALL LIKE THE IDEA OF TRACKING A SHRTWV ALONG THE BNDRY BY THE AFTERNOON HOURS. THIS WOULD INCRS LIFT AND SHEAR ALONG THE FRONTAL ZONE. THESE INGREDIENTS WITH SOME WEAK INSTABILITY MAY BE SUFFICIENT TO OVERCOME A MODERATELY STRONG CAP ALONG THE BOUNDARY. THUS...A MENTION OF THUNDERSTORMS WAS ADDED. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... OVERALL...CONFIDENCE IN EXTENDED FORECAST IS LOWER THAN NORMAL...SIMILAR TO YESTERDAY. FRONT WILL STILL BE HUNG UP TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...PROBABLY TO THE NORTH OF THE REGION. ALTHOUGH COLD FRONT WILL LIKELY BEGIN TO CROSS THE REGION ON THURSDAY...GFS/ECMWF CANNOT DECIDE WHETHER THE COLD FRONT WILL TAKE 24 OR 48 HOURS TO PUSH ALL THE WAY THROUGH. HAVE BUMPED UP POPS TO LIKELY THURSDAY NIGHT...BUT OTHERWISE MADE LITTLE CHANGES TO POPS OR TEMPERATURES. && .AVIATION /10Z SUNDAY THROUGH THURSDAY/... VFR CONDITIONS WL CONTINUE THIS MRNG ALTHOUGH BROAD SWATH OF MID LVL CLDINESS CONTS TO FLOW OVR THE UPR OH VALLEY REGION. STRONG LOW PRES CROSSING THE GREAT LAKES WL DRAG A WEAK FRONT ACRS AREA PORTS TODAY. GIVEN THE INITIALLY PALTRY BNDRY LAYER MSTR SUPPLY AND EXPECTED EWD PROGRESS OF THE SPPRTG SHRTWV...FORECAST WL FEATURE -SHRA WITH HIGH BASED CIGS AND VEERED WIND...GUSTS OF WHICH MAY APPRCH 30 KT SHOULD NAM AND RAP MOMENTUM TRANSFER PROGNOSIS BE REALIZED. CONFIDENCE IN MORE SIGNIFICANT OR WIDESPREAD DETERIORATION IS NOT SUFFICIENT TO WARRANT TAF MENTION JUST YET. .OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/... THE BOUNDARY SHOULD SHIFT SOUTH OF THE REGION TONIGHT...THEN BE PULLED NORTHWARD ONCE AGAIN ON MONDAY AS LOW PRES DIGS ACRS THE GREAT LAKES. FRONT POSITIONING IS QUESTIONABLE THROUGH MUCH OF THE WEEK...SO OCCASIONAL RESTRICTIONS SHOULD BE ANTICIPATED. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS BISMARCK ND
958 AM CDT SUN APR 7 2013 .UPDATE... ISSUED AT 953 AM CDT SUN APR 7 2013 MAINLY CHANGES EARLY THIS MORNING...NOW GETTING SNOW FROM MINOT AND EAST. THE PRECIPITATION HAS MOVED EAST OF WILLISTON AND STANLEY. ALSO WARMING TEMPERATURES SOUTH CENTRAL KEEPING THE PRECIPITATION AS RAIN. CANCELLED THE FREEZING RAIN ADVISORY FOR ALL BUT MCLEAN COUNTY THROUGH NOON...AND EAST THROUGH HARVEY AND SOUTH THROUGH THE JAMES RIVER VALLEY THROUGH 7 PM. UPDATE ISSUED AT 708 AM CDT SUN APR 7 2013 UPDATE THIS MORNING MAINLY FOR TEMPERATURES. LOW PRESSURE OVER EASTERN MONTANA WITH HIGH PRESSURE OVER EASTERN NORTH DAKOTA EARLY THIS MORNING WITH A SOUTHEAST FLOW OVER WESTERN NORTH DAKOTA AND LIGHT WINDS IN THE CENTRAL. EXTENSIVE MVFR-IFR STRATUS ACROSS ALL OF WESTERN AND CENTRAL NORTH DAKOTA. THIS HAS KEPT TEMPERATURES FROM FALLING AS FAR AS FORECAST...AND DO NOT EXPECT TEMPERATURES TO DROP MUCH MORE THIS MORNING. THUS RAISED EARLY MORNING TEMPERATURES IN THE EAST FROM THE LOW TO MID 20S INTO THE UPPER 20S. BAND OF PRECIPITATION IS MOVING THROUGH THE WEST AND INTO CENTRAL NORTH DAKOTA. REPORT OF SOME MIXED PRECIPITATION AT WILLISTON AND A LITTLE UNDER AN INCH OF SNOW. THE WARMER THAN EXPECTED TEMPERATURES COMBINED WITH ROAD SURFACE TEMPERATURES AT OR ABOVE FREEZING IN MANY AREAS...SHOULD HELP TO DIMINISH THE EFFECTS OF ANY FREEZING RAIN. HOWEVER...EXPECT SECONDARY ROADS... SIDEWALKS AND PARKING LOTS MAY YET BECOME SLIPPERY. WILL HOLD OFF ON ANY UPDATES TO THE CURRENT FREEZING RAIN ADVISORY AND SEE IF WE CAN GET A FEW MORE REPORTS AFTER SUNRISE. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 329 AM CDT SUN APR 7 2013 THE MAIN FORECAST CHALLENGES FOR THE SHORT TERM INCLUDE PRECIPITATION TIMING AND TYPE. THE 00Z MODEL SUITE IS IN AGREEMENT...THUS HAVE UTILIZED A BLEND OF GUIDANCE. LATEST RADAR IMAGERY AT 330 AM CDT IS SHOWING SOME SCATTERED LIGHT RETURNS ACROSS THE SOUTHWEST....AND MORE WIDESPREAD LIGHT RETURNS OVER NORTHEASTERN MONTANA ASSOCIATED WITH A WEAK UPPER LEVEL IMPULSE. HOWEVER...SURFACE OBSERVATIONS HAVE NOT REFLECTED PRECIPITATION REACHING THE GROUND OVER THE SOUTHWEST. THE 05/06Z RAP SOLUTIONS DO NOT REFLECT THE LIGHT PRECIPITATION OVER THE NORTHEAST AT THIS TIME...BUT IT DOES PAINT SOME LIGHT PRECIPITATION ACROSS THE SOUTHWEST. THE 00Z GFS/ECMWF/NAM ALL SHOW LIGHT PRECIPITATION OVER NORTHEAST MONTANA AT THIS TIME...AND THUS HAVE UTILIZED A BLEND OF THE 00Z MODEL GUIDANCE IN ADDITION TO THE 05/06Z RAP GUIDANCE. PRECIPITATION WILL CONTINUE TO SPREAD EAST WITH TIME...FILLING IN OVER THE WEST OVER THE NEXT FEW HOURS...AND THEN OVER THE CENTRAL BY LATER THIS MORNING...AS THE UPPER LEVEL IMPULSE MOVES OVER THE AREA. LATEST OBSERVATIONS AT 400 AM CDT SHOW THAT TEMPERATURES SOUTH AND WEST OF THE MISSOURI RIVER REMAIN ABOVE FREEZING...WHILE NORTH AND EAST...TEMPERATURES ARE IN THE MID TO UPPER 20S. FOLLOWING THE COLD FRONTAL PASSAGE YESTERDAY...COLD AIR ADVECTION ALOFT IS UNDERWAY...WITH A SHALLOW WARM LAYER JUST ABOVE THE SURFACE. PRECIPITATION WILL START AS FREEZING RAIN...WITH SOME SNOW AND SLEET MIXED IN ACROSS THE WEST...BUT AS TEMPERATURES WARM ACROSS THE SOUTHWEST AND SOUTH CENTRAL...A TRANSITION TO RAIN WILL OCCUR. FOR LOCATIONS ACROSS THE NORTH...WHERE TEMPERATURES ARE CURRENTLY SUBFREEZING...PRECIPITATION WILL START AS SNOW...BUT AS TEMPERATURES WARM NEAR THE SURFACE WITH COLDER AIR PRESENT ALOFT...A TRANSITION TO FREEZING RAIN AND THEN TO A MIX OF FREEZING RAIN...SLEET...AND SNOW AFTER MIDNIGHT. EVEN THOUGH THE FORECAST PROCESS HAS LED TO INCREASED MIXED PRECIPITATION (SNOW...SLEET AND FREEZING RAIN) AND DECREASED COVERAGE OF FREEZING RAIN...HAVE DECIDED TO CONTINUE THE FREEZING RAIN ADVISORY AT THIS TIME. WILL CONTINUE TO MONITOR AND MAKE CHANGES IF WARRANTED. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 329 AM CDT SUN APR 7 2013 THE MAIN FORECAST PROBLEM IN THE EXTENDED PERIOD WILL MONDAY THROUGH MONDAY NIGHT...ACTUALLY BEGINNING LATE SUNDAY NIGHT IN THE FAR WEST. WILL LEAN MORE TOWARD A ECMWF/GEM SOLUTION OVER THE GFS/NAM FOR QPF DETAILS. ALTHOUGH THE STRONG UPPER LEVEL SYSTEM IN THE WEST DIVES SOUTH ON MONDAY...THERE IS STILL A PIECE OF UPPER LEVEL ENERGY THAT MAKES IT INTO THE NORTHERN PLAINS. DETERMINISTIC MODELS ARE IN REASONABLE AGREEMENT IN BRINGING THIS INTO THE LOCAL AREA. ALTHOUGH RATHER SIGNIFICANT DIFFERENCES IN THE RESULTING PLACEMENT OF THE QPF AS THE WAVE INTERACT WITH A TIGHTENING BAROCLINIC ZONE ACROSS WESTERN AND CENTRAL NORTH DAKOTA. THE NAM/GFS ARE FARTHER NORTH WITH THE QPF THAN THE GEM/ECMWF...ALTHOUGH THE 00 UTC SUNDAY ECMWF HAS COME A LITTLE FARTHER NORTH THAN PREVIOUS RUNS. LOOKING AT GFS BUFKIT SOUNDINGS...THERE DOES APPEAR TO BE A 3 TO 6 HOUR PERIOD WITH STRONG OMEGA OVER WITHIN THE SNOW GROWTH ZONE IN THE WEST CENTRAL AND SOUTHWEST...WHICH SHOULD YIELD SOME DECENT SNOW AMOUNTS. THIS AREA EXTENDS EAST ACROSS CENTRAL NORTH DAKOTA DURING THE DAY MONDAY BUT STRONG HIGH PRESSURE DROPPING SOUTH FROM CANADA WILL INHIBIT FG FORCING LATER IN THE DAY. THIS SHOULD REDUCE SNOW AMOUNTS AS THE WAVE MOVES EASTWARD INTO CENTRAL AND EASTERN NORTH DAKOTA. A COMBINATION OF HPC SNOW AMOUNTS WITH MODEL QPF YIELDS 3 TO 5 INCHES OF SNOW OVER MUCH OF WEST CENTRAL AND SOUTHWEST NORTH DAKOTA...WITH 2 TO 3 INCHES EXTENDING EAST INTO GRANT AND MORTON COUNTIES. SNOW TOTALS TAPER TO AN INCH OR TWO EAST OF THE MISSOURI RIVER. THE NORTHERN EXTENT OF THE HEAVIER SNOW REMAINS ALONG AND SOUTH OF LAKE SAKAKAWEA...WEST OF THE MISSOURI...THEN ALONG AND SOUTH OF THE I94 CORRIDOR EAST OF THE MISSOURI. ALTHOUGH SIGNIFICANT DIFFERENCES STILL REMAIN...FEEL CONFIDENT ENOUGH THAT A WINTER WEATHER ADVISORY IS WARRANTED OVER THE SOUTHWEST AND WEST CENTRAL. CONFIDENCE WANES AS YOU GO EAST...BUT WILL EXTEND THE ADVISORY EAST TO COVER MOST OF THE AREA WEST OF THE MISSOURI AND SOUTH OF THE LAKE. AT THIS TIME IT APPEARS THAT THERE SHOULD BE A QUICK TRANSITION FROM RAIN TO SNOW AS COLD AIR RUSHES SOUTH LATE SUNDAY NIGHT. HOWEVER...A PERIOD OF MIXED PRECIPITATION CANNOT BE RULED OUT BEFORE THE COLD AIR IS FIRMLY ENTRENCHED OVER THE AREA BY MONDAY MORNING. AS THE CANADIAN HIGH DROPS SOUTH WE SHOULD SEE A NICE ISALLOBARIC COMPONENT MOVE ACROSS THE WEST AND SOUTH CENTRAL ON MONDAY RESULTING IN SUSTAINED WINDS OF 15 TO 20 MPH AND GUST OF 25 TO 30 MPH. ALTHOUGH THERE IS NO LOOSE SNOW...WINDS WILL BE STRONG ENOUGH FOR SOME BLOWING SNOW AS IT FALLS. THUS WILL MAKE THE ADVISORY FOR SNOW AND BLOWING SNOW...LASTING FROM LATE SUNDAY NIGHT THROUGH LATE MONDAY NIGHT. AS THE MAIN UPPER LOW MOVES ONTO THE PLAINS ON TUESDAY...COLD HIGH PRESSURE OVER SASKATCHEWAN INTO NORTH DAKOTA SHOULD KEEP THE NORTHERN EXTEND OF THE SYSTEM RIGHT ALONG THE SOUTH DAKOTA BORDER WITH ANY SIGNIFICANT PRECIPITATION REMAINING SOUTH OF THE STATE. THEN AS THE SYSTEM BEGINS TO EJECT NORTHEAST TUESDAY NIGHT THE PRECIPITATION SHIELD TRIES TO PUSH A BIT FARTHER NORTH AND MAY CLIP THE FAR SOUTH AND SOUTHEAST COUNTIES WITH LIGHT SNOW. AT THIS TIME WE ARE KEEPING HIGH CHANCE POPS ALONG THE SOUTH DAKOTA BORDER...TAPERING TO SLIGHT CHANCE POPS AROUND INTERSTATE 94. THE NORTHERN HALF OF THE CWA IS EXPECTED TO REMAIN DRY TUESDAY AND TUESDAY NIGHT. TEMPERATURES DURING THIS PERIOD...MONDAY THROUGH WEDNESDAY...WILL BE BELOW NORMAL WITH 20S NORTH TO 30S SOUTH. WE DO SEE SOME SLIGHT WARMING BY AROUND THURSDAY AS THE SYSTEM EXITS TO OUR EAST...BUT A PROGRESSIVE NORTHWEST FLOW WILL BRING A SERIES OF UPPER LEVEL WAVES INTO THE AREA LATE IN THE WEEK KEEPING OUR WEATHER UNSETTLED WITH TEMPERATURES NEAR OR BELOW NORMAL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 708 AM CDT SUN APR 7 2013 WIDESPREAD STRATUS REMAINS OVER THE REGION THIS MORNING. THE MAIN HAZARDS TO AVIATION INCLUDE THE MVFR/IFR CONDITIONS ASSOCIATED WITH THE STRATUS...AND FREEZING RAIN AND MIXED PRECIPITATION EXPECTED TO MOVE THROUGH SOUTH CENTRAL NORTH DAKOTA THROUGHOUT THE DAY. TEMPERATURES WARMER AT KDIK/KBIS...LIGHT RAIN THERE. A BRIEF BREAK IN PRECIPITATION WILL BE POSSIBLE LATER THIS AFTERNOON...BEFORE THE NEXT ROUND OF LIGHT RAIN AND MIXED PRECIPITATION ARRIVES SUNDAY EVENING AND MONDAY MORNING. && .BIS WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 1 AM CDT /MIDNIGHT MDT/ MONDAY TO 1 AM CDT /MIDNIGHT MDT/ TUESDAY FOR NDZ017>020-031>034-040>044. FREEZING RAIN ADVISORY UNTIL 7 PM CDT THIS EVENING FOR NDZ022- 023-036-037-047-048-050-051. FREEZING RAIN ADVISORY UNTIL 1 PM CDT THIS AFTERNOON FOR NDZ021. && $$ UPDATE...WAA SHORT TERM...LTH LONG TERM...TWH AVIATION...WAA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
708 AM CDT SUN APR 7 2013 .UPDATE... ISSUED AT 708 AM CDT SUN APR 7 2013 UPDATE THIS MORNING MAINLY FOR TEMPERATURES. LOW PRESSURE OVER EASTERN MONTANA WITH HIGH PRESSURE OVER EASTERN NORTH DAKOTA EARLY THIS MORNING WITH A SOUTHEAST FLOW OVER WESTERN NORTH DAKOTA AND LIGHT WINDS IN THE CENTRAL. EXTENSIVE MVFR-IFR STRATUS ACROSS ALL OF WESTERN AND CENTRAL NORTH DAKOTA. THIS HAS KEPT TEMPERATURES FROM FALLING AS FAR AS FORECAST...AND DO NOT EXPECT TEMPERATURES TO DROP MUCH MORE THIS MORNING. THUS RAISED EARLY MORNING TEMPERATURES IN THE EAST FROM THE LOW TO MID 20S INTO THE UPPER 20S. BAND OF PRECIPITATION IS MOVING THROUGH THE WEST AND INTO CENTRAL NORTH DAKOTA. REPORT OF SOME MIXED PRECIPITATION AT WILLISTON AND A LITTLE UNDER AN INCH OF SNOW. THE WARMER THAN EXPECTED TEMPERATURES COMBINED WITH ROAD SURFACE TEMPERATURES AT OR ABOVE FREEZING IN MANY AREAS...SHOULD HELP TO DIMINISH THE EFFECTS OF ANY FREEZING RAIN. HOWEVER...EXPECT SECONDARY ROADS... SIDEWALKS AND PARKING LOTS MAY YET BECOME SLIPPERY. WILL HOLD OFF ON ANY UPDATES TO THE CURRENT FREEZING RAIN ADVISORY AND SEE IF WE CAN GET A FEW MORE REPORTS AFTER SUNRISE. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 329 AM CDT SUN APR 7 2013 THE MAIN FORECAST CHALLENGES FOR THE SHORT TERM INCLUDE PRECIPITATION TIMING AND TYPE. THE 00Z MODEL SUITE IS IN AGREEMENT...THUS HAVE UTILIZED A BLEND OF GUIDANCE. LATEST RADAR IMAGERY AT 330 AM CDT IS SHOWING SOME SCATTERED LIGHT RETURNS ACROSS THE SOUTHWEST....AND MORE WIDESPREAD LIGHT RETURNS OVER NORTHEASTERN MONTANA ASSOCIATED WITH A WEAK UPPER LEVEL IMPULSE. HOWEVER...SURFACE OBSERVATIONS HAVE NOT REFLECTED PRECIPITATION REACHING THE GROUND OVER THE SOUTHWEST. THE 05/06Z RAP SOLUTIONS DO NOT REFLECT THE LIGHT PRECIPITATION OVER THE NORTHEAST AT THIS TIME...BUT IT DOES PAINT SOME LIGHT PRECIPITATION ACROSS THE SOUTHWEST. THE 00Z GFS/ECMWF/NAM ALL SHOW LIGHT PRECIPITATION OVER NORTHEAST MONTANA AT THIS TIME...AND THUS HAVE UTILIZED A BLEND OF THE 00Z MODEL GUIDANCE IN ADDITION TO THE 05/06Z RAP GUIDANCE. PRECIPITATION WILL CONTINUE TO SPREAD EAST WITH TIME...FILLING IN OVER THE WEST OVER THE NEXT FEW HOURS...AND THEN OVER THE CENTRAL BY LATER THIS MORNING...AS THE UPPER LEVEL IMPULSE MOVES OVER THE AREA. LATEST OBSERVATIONS AT 400 AM CDT SHOW THAT TEMPERATURES SOUTH AND WEST OF THE MISSOURI RIVER REMAIN ABOVE FREEZING...WHILE NORTH AND EAST...TEMPERATURES ARE IN THE MID TO UPPER 20S. FOLLOWING THE COLD FRONTAL PASSAGE YESTERDAY...COLD AIR ADVECTION ALOFT IS UNDERWAY...WITH A SHALLOW WARM LAYER JUST ABOVE THE SURFACE. PRECIPITATION WILL START AS FREEZING RAIN...WITH SOME SNOW AND SLEET MIXED IN ACROSS THE WEST...BUT AS TEMPERATURES WARM ACROSS THE SOUTHWEST AND SOUTH CENTRAL...A TRANSITION TO RAIN WILL OCCUR. FOR LOCATIONS ACROSS THE NORTH...WHERE TEMPERATURES ARE CURRENTLY SUBFREEZING...PRECIPITATION WILL START AS SNOW...BUT AS TEMPERATURES WARM NEAR THE SURFACE WITH COLDER AIR PRESENT ALOFT...A TRANSITION TO FREEZING RAIN AND THEN TO A MIX OF FREEZING RAIN...SLEET...AND SNOW AFTER MIDNIGHT. EVEN THOUGH THE FORECAST PROCESS HAS LED TO INCREASED MIXED PRECIPITATION (SNOW...SLEET AND FREEZING RAIN) AND DECREASED COVERAGE OF FREEZING RAIN...HAVE DECIDED TO CONTINUE THE FREEZING RAIN ADVISORY AT THIS TIME. WILL CONTINUE TO MONITOR AND MAKE CHANGES IF WARRANTED. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 329 AM CDT SUN APR 7 2013 THE MAIN FORECAST PROBLEM IN THE EXTENDED PERIOD WILL MONDAY THROUGH MONDAY NIGHT...ACTUALLY BEGINNING LATE SUNDAY NIGHT IN THE FAR WEST. WILL LEAN MORE TOWARD A ECMWF/GEM SOLUTION OVER THE GFS/NAM FOR QPF DETAILS. ALTHOUGH THE STRONG UPPER LEVEL SYSTEM IN THE WEST DIVES SOUTH ON MONDAY...THERE IS STILL A PIECE OF UPPER LEVEL ENERGY THAT MAKES IT INTO THE NORTHERN PLAINS. DETERMINISTIC MODELS ARE IN REASONABLE AGREEMENT IN BRINGING THIS INTO THE LOCAL AREA. ALTHOUGH RATHER SIGNIFICANT DIFFERENCES IN THE RESULTING PLACEMENT OF THE QPF AS THE WAVE INTERACT WITH A TIGHTENING BAROCLINIC ZONE ACROSS WESTERN AND CENTRAL NORTH DAKOTA. THE NAM/GFS ARE FARTHER NORTH WITH THE QPF THAN THE GEM/ECMWF...ALTHOUGH THE 00 UTC SUNDAY ECMWF HAS COME A LITTLE FARTHER NORTH THAN PREVIOUS RUNS. LOOKING AT GFS BUFKIT SOUNDINGS...THERE DOES APPEAR TO BE A 3 TO 6 HOUR PERIOD WITH STRONG OMEGA OVER WITHIN THE SNOW GROWTH ZONE IN THE WEST CENTRAL AND SOUTHWEST...WHICH SHOULD YIELD SOME DECENT SNOW AMOUNTS. THIS AREA EXTENDS EAST ACROSS CENTRAL NORTH DAKOTA DURING THE DAY MONDAY BUT STRONG HIGH PRESSURE DROPPING SOUTH FROM CANADA WILL INHIBIT FG FORCING LATER IN THE DAY. THIS SHOULD REDUCE SNOW AMOUNTS AS THE WAVE MOVES EASTWARD INTO CENTRAL AND EASTERN NORTH DAKOTA. A COMBINATION OF HPC SNOW AMOUNTS WITH MODEL QPF YIELDS 3 TO 5 INCHES OF SNOW OVER MUCH OF WEST CENTRAL AND SOUTHWEST NORTH DAKOTA...WITH 2 TO 3 INCHES EXTENDING EAST INTO GRANT AND MORTON COUNTIES. SNOW TOTALS TAPER TO AN INCH OR TWO EAST OF THE MISSOURI RIVER. THE NORTHERN EXTENT OF THE HEAVIER SNOW REMAINS ALONG AND SOUTH OF LAKE SAKAKAWEA...WEST OF THE MISSOURI...THEN ALONG AND SOUTH OF THE I94 CORRIDOR EAST OF THE MISSOURI. ALTHOUGH SIGNIFICANT DIFFERENCES STILL REMAIN...FEEL CONFIDENT ENOUGH THAT A WINTER WEATHER ADVISORY IS WARRANTED OVER THE SOUTHWEST AND WEST CENTRAL. CONFIDENCE WANES AS YOU GO EAST...BUT WILL EXTEND THE ADVISORY EAST TO COVER MOST OF THE AREA WEST OF THE MISSOURI AND SOUTH OF THE LAKE. AT THIS TIME IT APPEARS THAT THERE SHOULD BE A QUICK TRANSITION FROM RAIN TO SNOW AS COLD AIR RUSHES SOUTH LATE SUNDAY NIGHT. HOWEVER...A PERIOD OF MIXED PRECIPITATION CANNOT BE RULED OUT BEFORE THE COLD AIR IS FIRMLY ENTRENCHED OVER THE AREA BY MONDAY MORNING. AS THE CANADIAN HIGH DROPS SOUTH WE SHOULD SEE A NICE ISALLOBARIC COMPONENT MOVE ACROSS THE WEST AND SOUTH CENTRAL ON MONDAY RESULTING IN SUSTAINED WINDS OF 15 TO 20 MPH AND GUST OF 25 TO 30 MPH. ALTHOUGH THERE IS NO LOOSE SNOW...WINDS WILL BE STRONG ENOUGH FOR SOME BLOWING SNOW AS IT FALLS. THUS WILL MAKE THE ADVISORY FOR SNOW AND BLOWING SNOW...LASTING FROM LATE SUNDAY NIGHT THROUGH LATE MONDAY NIGHT. AS THE MAIN UPPER LOW MOVES ONTO THE PLAINS ON TUESDAY...COLD HIGH PRESSURE OVER SASKATCHEWAN INTO NORTH DAKOTA SHOULD KEEP THE NORTHERN EXTEND OF THE SYSTEM RIGHT ALONG THE SOUTH DAKOTA BORDER WITH ANY SIGNIFICANT PRECIPITATION REMAINING SOUTH OF THE STATE. THEN AS THE SYSTEM BEGINS TO EJECT NORTHEAST TUESDAY NIGHT THE PRECIPITATION SHIELD TRIES TO PUSH A BIT FARTHER NORTH AND MAY CLIP THE FAR SOUTH AND SOUTHEAST COUNTIES WITH LIGHT SNOW. AT THIS TIME WE ARE KEEPING HIGH CHANCE POPS ALONG THE SOUTH DAKOTA BORDER...TAPERING TO SLIGHT CHANCE POPS AROUND INTERSTATE 94. THE NORTHERN HALF OF THE CWA IS EXPECTED TO REMAIN DRY TUESDAY AND TUESDAY NIGHT. TEMPERATURES DURING THIS PERIOD...MONDAY THROUGH WEDNESDAY...WILL BE BELOW NORMAL WITH 20S NORTH TO 30S SOUTH. WE DO SEE SOME SLIGHT WARMING BY AROUND THURSDAY AS THE SYSTEM EXITS TO OUR EAST...BUT A PROGRESSIVE NORTHWEST FLOW WILL BRING A SERIES OF UPPER LEVEL WAVES INTO THE AREA LATE IN THE WEEK KEEPING OUR WEATHER UNSETTLED WITH TEMPERATURES NEAR OR BELOW NORMAL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 708 AM CDT SUN APR 7 2013 WIDESPREAD STRATUS REMAINS OVER THE REGION THIS MORNING. THE MAIN HAZARDS TO AVIATION INCLUDE THE MVFR/IFR CONDITIONS ASSOCIATED WITH THE STRATUS...AND FREEZING RAIN AND MIXED PRECIPITATION EXPECTED TO MOVE FROM WESTERN...INTO CENTRAL NORTH DAKOTA THROUGHOUT THE DAY. AS TEMPERATURES WARM AT KDIK...LIGHT FREEZING RAIN WILL GIVE WAY TO LIGHT RAIN. A BRIEF BREAK IN PRECIPITATION WILL BE POSSIBLE LATER THIS AFTERNOON...BEFORE THE NEXT ROUND OF LIGHT RAIN AND MIXED PRECIPITATION ARRIVES SUNDAY EVENING AND MONDAY MORNING. && .BIS WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 1 AM CDT /MIDNIGHT MDT/ MONDAY TO 1 AM CDT /MIDNIGHT MDT/ TUESDAY FOR NDZ017>020-031>034-040>044. FREEZING RAIN ADVISORY UNTIL 1 PM CDT THIS AFTERNOON FOR NDZ002- 010-019>021-034-035-046. FREEZING RAIN ADVISORY UNTIL 11 AM CDT /10 AM MDT/ THIS MORNING FOR NDZ001-009-017-018-033-041. FREEZING RAIN ADVISORY FROM 11 AM THIS MORNING TO 7 PM CDT THIS EVENING FOR NDZ003-011-012-022-023-036-037-047-048-050-051. && $$ UPDATE...TWH SHORT TERM...LTH LONG TERM...TWH AVIATION...LTH
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
652 AM EDT SUN APR 7 2013 .SYNOPSIS... COLD FRONT STALLS ACROSS THE EXTREME NORTHERN SECTIONS OVERNIGHT...THEN LIFTS BACK NORTH DURING THE DAY ON MONDAY. WEATHER REMAINS UNSETTLE TUESDAY AND WEDNESDAY. A STRONG COLD FRONT PASSES THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... 630 AM UPDATE... CONTINUED TO NUDGE POPS DOWNWARD BETWEEN THE 12Z-18Z TIME FRAME WITH VERY LIMITED MOISTURE PER LATEST RUC SOUNDINGS AND NEAR-TERM CONVECTIVE OUTPUT. STILL WILL ALLOW FOR SOME LATE-DAY DEVELOPMENT ACROSS THE NORTHERN ZONES AROUND THE 21Z SUN-00Z MON TIME FRAME. ALSO...LATEST NAM12.06 GUIDANCE COMING IN WITH CONTINUED ELEVATED INSTABILITY ACROSS THE NORTHERN ZONES BETWEEN 00Z-06Z TONIGHT. EL/S AND CLOUD TOPS LOOK LOW ENOUGH TO LEAVE THUNDER OUT BUT SOMETHING FOR THE NEXT SHIFT TO EXAMINE. PREVIOUS FORECAST... 04Z SURFACE OBS DEPICTING SUBTLE WIND SHIFT ACROSS FORECAST AREA ROUGHLY FROM THE NW OHIO ZONES SE-WARD TOWARDS NICHOLAS/FAYETTE COUNTIES IN WV. SOUTH OF THIS FEATURE WIND DIRECTION S/SSW WITH RECOVERING DEWPOINTS GENERALLY IN THE LOWER 30S WHILE NORTH OF THIS BOUNDARY WIND DIRECTION MORE SSE WITH DEWPOINTS STILL DOWN IN THE UPPER TEENS TO LOWER 20S. A WEAK LINE OF SHOWERS STRETCHED FROM FAR NW OHIO INTO CENTRAL INDIANA AND WAS PUSHING ENE-WARD. APPEARS HOWEVER VERY LITTLE PRECIP WAS ACTUALLY REACHING THE SURFACE HOWEVER AS NOT FINDING ANY SFC OBS OUT THAT WAY REPORTING ANY PRECIP WITH VERY HIGH CLOUD BASES STILL AROUND 10KFT. S/W TROUGH AND SFC LOW PRESSURE TO AFFECT THE AREA TODAY STILL CURRENTLY OUT OVER THE UPPER MIDWEST...WITH LOW PRESSURE CENTERED OVER WESTERN WI. PRIMARY FORECAST CONCERN FOR THIS PERIOD REVOLVED AROUND APPROACHING COLD FRONT AND SUBSEQUENT SHOWERS/THUNDERSTORMS CHANCES. OPERATIONAL NWP IN GOOD AGREEMENT WITH REGARD TO GENERAL FEATURES SUNDAY. AFOREMENTIONED S/W TROUGH AND SFC LOW CONTINUING EASTWARD TODAY FROM UPPER MICHIGAN AT 12Z TO SW QUEBEC BY 00Z MON. COLD FRONT ASSOC WITH IT WILL PROGRESS EASTWARD AS WELL BUT WILL STALL OUT WEST TO EAST NEAR OR JUST NORTH OF THE CWA BORDER BY 00Z MON AS IT ENCOUNTERS INCREASING W/SW UNIDIRECTIONAL FLOW. INTERESTINGLY ENOUGH...DESPITE THE PASSAGE OF THE S/W TROUGH TO THE NORTH HEIGHTS ACTUALLY REMAIN CONSTANT OR EVEN RISE A BIT TODAY. PRECIP CHANCES SOMEWHAT PROBLEMATIC TODAY WITH A COUPLE OF LIMITING FACTORS TO CONSIDER. FIRST...AS THE COLD FRONT SLOWS ACROSS CENTRAL OHIO BEST LLVL MOISTURE CONTINUES ESE-WARD AWAY FROM FRONTAL CONVERGENCE WHICH MAY HINDER CONTINUED DEVELOPMENT. SECOND...DESPITE THE WARMER DEWPOINTS TEMPS...A STOUT DRY LAYER STILL EXISTS. LATEST NAM STILL DEPICTING A 20-25F DEGREE DEWPOINTS DEPRESSION EARLY/MID AFTERNOON AT LOCATIONS SUCH AS PKB...AND SUSPECT THAT THOSE PROGGED DEWPOINTS IN THE UPPER 40S STILL MAY BE ON THE HIGH SIDE. NEAR-TERM CONVECTIVE MODELS ALL SHOW ANY POTENTIAL LINE OF SHOWERS LIMPING INTO THE AREA AND DISSIPATING AS IT DOES SO. NOT GOING TO DRASTICALLY CUT POPS WITH THIS FORECAST PACKAGE BUT WILL REDUCE THEM TO CHANCE CATEGORY AT BEST. WILL ALSO CONTINUE TO KEEP THE SOUTHERN COALFIELDS AND VA COUNTIES DRY. REGARDING ANY THUNDER POTENTIAL...AN AXIS OF INSTABILITY MOVES IN BTWN 18Z SUN AND 00Z MON AHEAD OF FRONT WITH SFC-BASED CAPE AROUND 300J/KG AND MUCAPE VALUES UP TO AROUND 600J/KG ACROSS THE NW ZONES. WITH THAT IN MIND WILL CARRY CHANCE THUNDER DURING THIS TIME ROUGHLY ALONG AND NW OF A LINE FROM CKB TO HTS. ANY CONVECTION WILL BE HIGH-BASED OF COURSE AND WITH DCAPE VALUES 800-1000J...CAN/T RULE OUT THE POSSIBILITY OF A BRIEF GUST HERE OR THERE AROUND 20-30KTS WITH A STORM. OUTSIDE OF PRECIP POTENTIAL...MAX TEMPS ONCE AGAIN CLIMB INTO THE UPPER 60S/LOWER 70S LOWLANDS WITH PERHAPS MID 60S FAR NW ZONES WITH ADDITIONAL CLOUD COVER. BETWEEN 00Z MON-12Z MON THE COLD FRONT REMAINS ESSENTIALLY STALLED BUT MAY MAKE SOME INROADS JUST INTO THE NORTHERN ZONES BEFORE RETREATING NORTHWARD TOWARDS DAWN MON. HIGHEST CHANCE POPS WILL BE ACROSS NE ZONES BUT WILL GENERALLY BEGIN TO WANE DURING THE OVERNIGHT HOURS...WITH ONLY A SLIGHT CHANCE OF PRECIP FOR LOWLANDS NORTH OF INTERSTATE 64. A BIT MORE LLVL MOISTURE ARRIVES ALONG WITH SOME ADDED LIFT FROM AN APPROACHING VORT MAX TO BUMP UP PRECIP POTENTIAL TOWARDS THE DAWN HOURS. && .SHORT TERM /MONDAY THROUGH WEDNESDAY/... GFS/ECMWF MODELS IN AGREEMENT WITH H1000 KINK OF THE EAST TO WEST QUASI STATIONARY FRONTAL BOUNDARY JUST NORTH OF THE AREA...AND THE NAM FURTHER SOUTH JUST ALONG OUR BORDER BY 12Z MONDAY. EITHER WAY...PCPN AHEAD OF THE FRONT COULD REACH OUR NORTHERN SECTORS...SO KEPT HIGH CHANCE POPS THROUGH MONDAY NIGHT INCLUDING NORTHEAST MOUNTAINS. THIS SCENARIO WILL KEEP MOST OF THE AREA UNDER THE WARM SECTOR FOR WARMER THAN SEASONAL TEMPERATURES THROUGH THE PERIOD. THE CMC/ECMWF BRING A SHORT WAVE AND ASSOCIATED VORTICITY MAX NORTH OF THE AREA...SUGGESTING MID LEVEL ENERGY COULD INFLUENCE THE AFOREMENTIONED BOUNDARY TO PRODUCE SHOWERS OR STORMS NORTH OF OUR CWA. HOWEVER...THE GFS VORT MAX MOVES ACROSS SOUTHEAST OH BY 12Z MONDAY...QUICKLY MOVING NORTHEAST AND A SECOND VORT MAX BY 00Z TUESDAY. IF THE GFS SOLUTION MATERIALIZE...COULD SEE MORE CONVECTION DEVELOPING AROUND THE QUASI STATIONARY BOUNDARY LATE MONDAY...MAINLY ACROSS THE NORTH AND NORTHEAST MOUNTAINS. ADJUSTED DOWN POPS ACROSS THE EXTREME SOUTHERN CWA AS MAY NOT SEE MORE THAN AN ISOLATED SHOWER IF ANY MONDAY THROUGH TUESDAY. KEPT TEMPERATURES AS PREVIOUS FORECAST AS THEY LOOK ON TRACK WITH A WARMING TREND EXPECTED THROUGH MID WEEK UNDER SOUTHWEST FLOW. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... FLAT RIDGING EARLY ON GIVES WAY TO TROUGHINESS LATE IN THE WEEK. STILL A QUESTION OF WHERE AN E-W FRONT BENEATH THE W FLOW ALOFT ENDS UP. THE ECMWF SHOWS AN EASTERN CANADIAN TROUGH DIGGING INTO THE NORTHEASTERN STATES...PUSHING A SURFACE FRONT INTO THE CWA TUE NT-WED AND SO DOES HPC...EVEN AS OTHER MODELS HAVE STRONGER RIDGING OVER THE AREA BY THAT TIME...PUSHING THE NORTHERN STREAM TROUGH FARTHER N. AS SUCH...HAVE A SLIGHT CHANCE FOR SHOWERS N TUE NT FOLLOWED BY A MODEST INCREASE IN POPS FROM THE W WED PER DIURNAL CONSIDERATIONS IN THE INCREASINGLY WARM AND SOMEWHAT HUMID AIR...AND A COLD FRONT APPROACHING FROM THE W. TIME OF YEAR AND RECENT TRENDS DO FAVOR ECMWF/HPC HERE. ECMWF AND HPC ARE ALSO ONLY SOLNS HOLDING BACK COLD FRONT FROM THE W UNTIL FRI...GRANTED THE 12Z ECMWF LOOKS ALMOST EXACTLY LIKE HPC DEPICTION FOR FRI. OPTED WITH A COMPROMISE AND SOMEWHAT SMOOTHED SOLN WITH THE HIGHEST POPS THU AND THU NT WHEN SHOWERS ARE LIKELY. POPS...TEMPERATURES AND DEW POINTS GRADUALLY DECREASE FRI AND FRI NT /NOTWITHSTANDING THE DIURNAL RISE IN TEMPERATURES FRI/ WITH THE FRONTAL PASSAGE IN AGREEMENT WITH THE HPC WIND FIELDS. THE INCREASINGLY WARM AND HUMID AIR WILL EVENTUALLY PROVIDE INSTABILITY ESPECIALLY BUT NOT EXCLUSIVELY WITH THE AFTERNOON HEATING...AND AVAILABLE FOR STRENGTHENING FLOW AND FORCING TO ACT ON AS THE FRONT APPROACHES. WHILE MODEL DIFFERENCES WITH THE SYNOPTIC SCENARIO ARE STILL TO GREAT TO HONE IN ON SPECIFIC PARAMETERS...IT SEEMS REASONABLE WE MAY BE LOOKING AT AT LEAST MARGINAL FAVORABILITY FOR SEVERE WED AND / OR THU...AND WELL HONE HWO CONVECTIVE MENTION INTRODUCED EARLY THIS MORNING IN ON THIS IDEA. IN THE WAKE OF TH FRONT...THE WEATHER COOLS DOWN AND DRIES OUT FOR THE START OF NEXT WEEKEND...ALTHOUGH NOT MUCH IF ANY BELOW NORMAL GIVEN ZONAL FLOW OF PACIFIC ORIGIN. BLENDED IN MOSGUIDE AND HPC FOR TEMPERATURES IN MOST CASES. THERE WERE NO MAJOR CHANGES ALTHOUGH NOW HAVE CRW HITTING 80 FOR THE FIRST TIME THIS YEAR ON WED...WHICH IS IN AGREEMENT WITH THE GFS ENSEMBLE MEAN AND HPC. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... 12Z SUNDAY THROUGH 12Z MONDAY... VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE VALID PERIOD. CIGS WILL LOWER AND THICKEN TODAY ACROSS THE NORTHERN PORTIONS OF THE AREA...BUT ARE EXPECTED TO REMAIN LOW VFR AROUND 5-7KFT AS A FRONTAL BOUNDARY APPROACHES THE REGION. A CHANCE OF PRECIP WILL ALSO ACCOMPANY THE FRONT WITH A CHANCE OF A THUNDERSTORM MAINLY THIS AFTERNOON ACROSS THE NORTH. BRIEF MVFR VIS IS POSSIBLE WITH A HEAVIER SHOWER AND/OR THUNDERSTORM. SURFACE WINDS WILL CONTINUE ON THE GUSTY SIDE TODAY OUT OF THE SOUTHWEST...WITH OCCASIONAL GUSTS AROUND 20KTS LOWLANDS AND 20-25 KT RANGE ACROSS HIGHER TERRAIN COUNTIES. ANOTHER AVIATION CONCERN AT THE OUTSET THIS MORNING IS A STRONG LOW LEVEL SOUTHWESTERLY JET CENTERED AROUND 1500FT AGL...WHERE WIND SPEEDS ARE AROUND 35-40KTS. THESE WIND SPEEDS SHOULD BEGIN TO SUBSIDE AROUND 14Z-15Z. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY... FORECAST CONFIDENCE...MEDIUM. ALTERNATE SCENARIOS: WIND GUSTS TODAY MAY BE STRONGER THAN FORECAST. TIMING OF FRONTAL BOUNDARY AND SHOWERS MAY VARY FROM FORECAST. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22 EDT 1HRLY 07 08 09 10 11 12 13 14 15 16 17 18 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H M H EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 12Z MONDAY... IFR POSSIBLE IN SHOWERS AND THUNDERSTORMS WEDNESDAY NIGHT AND THURSDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...ARJ/50 NEAR TERM...50 SHORT TERM...ARJ LONG TERM...TRM AVIATION...50
AREA FORECAST DISCUSSION...
NWS PORTLAND OR
855 AM PDT SUN APR 7 2013 .SYNOPSIS...A LOW PRESSURE SYSTEM IS NOW PUSHING EAST OF THE CASCADES THIS MORNING. SNOW IS FALLING IN THE HIGH CASCADES AND WILL INCREASE TODAY AS FLOW TURNS WESTERLY. SNOW LEVELS WILL BE NEAR OR BELOW THE CASCADE PASSES. ELSEWHERE RAIN WILL TAPER TO SHOWERS AND SCATTERED THUNDERSTORMS AS A COLD UPPER LEVEL LOW MOVES ONSHORE THIS AFTERNOON AND EVENING. THUNDERSTORMS MAY HAVE SMALL HAIL AND GUSTY WINDS THROUGH THIS EVENING. SHOWERS WILL LINGER INTO MONDAY...THEN TAPER OFF AS A RIDGE OF HIGH PRESSURE BUILDS FOR A DRIER AND WARMER WEATHER TUESDAY. ANOTHER SYSTEM IS EXPECTED TO BRING MORE RAIN WEDNESDAY. && .UPDATE...SURFACE LOW PRESSURE IS NOW FILLING AND MAKING A BEELINE EAST OF THE CASCADES THIS MORNING. WE DO STILL HAVE A PERIOD OF PRESSURE RISES BEHIND THE DEPARTING LOW...BUT WIND SUPPORT ALOFT HAS EASED FROM EARLIER WHERE WE SAW GUSTS TO 60 MPH IN THE COAST RANGE AND 52 MPH IN THE VALLEY. THIS WILL EASE THE GUST POTENTIAL SUPPORTING GUSTS OF 30-35 MPH IN THE VALLEY...WITH GUSTS 40-45 MPH IN THE HIGHER TERRAIN OF THE COAST RANGE. THEREFORE...WILL DROP THE WIND ADVISORY FOR THE VALLEY AND THE HIGH WIND WARNING FOR THE COAST RANGE. EXPECT IT TO REMAIN WINDY AT THE EAST END OF THE COLUMBIA RIVER GORGE AND THE CASCADES TODAY. COLD ADVECTION WILL CONTINUE TODAY...THUS DO NOT EXPECT MUCH WARMING FROM CURRENT READINGS. HIGHER ELEVATION SNOTELS IN WASHINGTON HAVE REPORTED ANYWHERE FROM 3-6 INCHES OF SNOWFALL SO FAR...2" AT THE SANTIAM PASS SUMMIT WITH 4" OR SO AT THE HIGHER ELEVATION SNOTELS OF NORTH OREGON...LIGHTER AMOUNTS IN LANE COUNTY WHERE FREEZING LEVELS ARE STILL A BIT HIGHER. EXPECT ANOTHER 4-6" OF SNOW POSSIBLE IN S WA...WITH 4-8" IN THE HIGHER ELEVATION CASCADE LOCATIONS TODAY. WEBCAMS CONFIRM SNOW IS NOW FALLING AT THE PASSES AND EXPECT SNOW LEVELS TO CONTINUE TO FALL. WITH REGARDS TO THUNDERSTORMS...WITH CURRENT READINGS IN THE MID TO UPPER 40S...WE DO NOT EXPECT SFC TEMPS TO RISE MUCH ABOVE 50 TODAY. DO EXPECT LAPSE RATES TO GET BETTER THIS AFTERNOON AS THE COLD POOL MOVES IN...AND STILL EXPECT SOME HEAVIER SHOWERS OR THUNDERSTORMS. KMD .SHORT TERM...DISCUSSION UNCHANGED....TODAY THROUGH WEDNESDAY...THE CIRCULATION OF A DEVELOPING LOW PRESSURE SYSTEM IS APPARENT ON KLGX/KRTX NWS DOPPLER RADARS...PRESENTLY MOVING INTO THE LONG BEACH PENINSULA OF PACIFIC COUNTY WA. THIS SYSTEM IS A LITTLE FARTHER NORTH AND A LITTLE STRONGER THAN MOST MODELS SUGGESTED...WITH BUOY 46029 AND HOME WEATHER STATIONS ON THE LONG BEACH PENINSULA REASONABLY SUGGESTING A CENTRAL PRESSURE OF ABOUT 997 MB. LATEST RUNS OF THE HRRR 3 KM MODEL DEPICT AN ELONGATED SHAPE TO THE LOW... EXTENDING FROM THE S WA COAST SOUTHWESTWARD. THIS APPEARS REASONABLE CONSIDERING THE WIND FIELD APPARENT ALONG THE COAST AND SHOWN BY BUOYS IN THE COASTAL WATERS. THUS THERE MAY BE A BIT OF A LULL TO THE WIND ALONG OUR NORTH COAST ZONES INITIALLY AS THE LOW MOVES ONSHORE. BEHIND THE LOW...HRRR AND NAM HAVE BEEN VERY INSISTENT ON A STRONG SURGE OF NW-W WIND IN THE BENT BACK OCCLUSION ON THE BACK SIDE OF THE LOW. THIS WILL CAUSE A SURGE OF WIND FROM THE SW-W AND EVENTUALLY NW WIND ALONG THE COAST IN THE COMING HOURS...SO IF ONE SURGE OF WIND EASES IT DOES NOT NECESSARILY MEAN THE EVENT IS OVER. THE CONSEQUENCES OF THE STRONGER LOW AND MORE NORTHERN TRACK WILL BE INCREASED CONFIDENCE IN THE WIND ADVISORY FOR THE WILLAMETTE VALLEY AND A LITTLE CONCERN THE STRONGER WINDS MAY PUSH INTO KELSO/LONGVIEW. ADDITIONALLY...IT APPEARS A LOW-END HIGH WIND WARNING WILL VERIFY FOR THE OREGON COAST AND COAST RANGE. WILL LEAVE ALL WIND HIGHLIGHTS AS IS FOR NOW...THE OVERALL FORECAST LOOKS PRETTY WELL ON TRACK WITH GUSTS 50-60 MPH WIDESPREAD FOR THE OR COAST AND LOCAL GUSTS TO 70 MPH FOR THE MOST EXPOSED AREAS. SOUTH WIND GUSTS 25-35 MPH ARE ALREADY DEVELOPING IN THE TUALATIN AND CENTRAL/SOUTH WILLAMETTE VALLEY. THESE WILL GET STRONGER WITH 35-45 MPH GUSTS LIKELY TO DEVELOP FOR THE WILLAMETTE VALLEY AND CLARK COUNTY WITHIN THE NEXT COUPLE HOURS AS PRESSURE RISES BEGIN IN EARNEST. ASIDE FROM TRACKING THE LOW AND ASSOCIATED WIND PATTERN THE OTHER FORECAST CHALLENGES OF THE DAY ARE...1. HOW PROLIFIC THUNDERSTORMS WILL BE TODAY AND 2. HOW MUCH SNOW WILL FALL IN THE CASCADES. THUNDERSTORMS...NAM BUFR SOUNDINGS SHOW A VERY STRONG DIRECTIONAL SHEAR PROFILE WILL QUICKLY BECOME UNIDIRECTIONAL AS THE MORNING PROGRESSES. HOWEVER A SECONDARY TROUGH IS EXPECTED TO MOVE IN LATER THIS AFTERNOON AS THE COLD POOL ALOFT DIPS INTO WESTERN WA AND NORTHWEST OREGON. LAPSE RATES LOOK MARGINAL FOR THUNDERSTORMS...BUT IMPROVE AS THE AFTERNOON PROGRESSES. WITH SFC TEMPS IN THE LOW 50S WE SHOULD BE ABLE TO MUSTER ABOUT 400-600 J/KG OF CAPE AND LIFTED INDICES OF -2 TO -3 DEG C...WHICH WITH LITTLE TO NO CAPPING WOULD BE PLENTY TO SUGGEST DEEP CONVECTION. SO WE INCREASED THUNDERSTORM COVERAGE TO SCATTERED AS THIS SETUP IS ABOUT AS GOOD AS IT GETS IN A POST-FRONTAL ENVIRONMENT. WITH 25-35 KT WESTERLY FLOW AT 850 MB ANY ORGANIZED THUNDERSTORMS MAY MIX DOWN GUSTY WINDS. TERRAIN DRIVEN FLOW MAY PRODUCE A LITTLE DIRECTIONAL SHEAR AS WELL...WHICH COULD LEAD TO SOME WEAK ROTATION WITH THE STRONGER CELLS. ANY THUNDERSTORMS SHOULD DIE DOWN QUICKLY AFTER SUNSET AS SFC TEMPS COOL AND THE AIR MASS STABILIZES. SNOW...SNOW AMOUNTS IN THE CASCADES HAVE THUS FAR BEEN UNIMPRESSIVE WITH ABOUT 2-4 INCHES MOST LOCATIONS ABOVE 4000 FT. HOWEVER AS LOW PRESSURE CROSSES THE CASCADES FLOW WILL BECOME MORE OROGRAPHIC. WEST WINDS 25-35 KT AT 850 MB WILL ENHANCE SNOWFALL IN THE CASCADES...SO A GOOD 6-12 INCHES LOOK LIKELY ABOVE 4500-5000 FT BY LATER TONIGHT. SNOW LEVELS WILL BE LOWERING...SO THE PASSES COULD GET A FEW SLUSHY INCHES OF SNOW THIS AFTERNOON AND TONIGHT. SNOW WILL GRADUALLY TAPER OFF MONDAY. A WEAK SHORTWAVE MAY KEEP A FEW SHOWERS IN THE REGION THROUGH MONDAY. HOWEVER IT APPEARS WE WILL DRY OUT BY TUESDAY AS RIDGING BUILDS INTO OREGON AND WASHINGTON. 850 MB TEMPS REBOUND TO ABOUT +5 DEG C TUE AFTERNOON...PROBABLY ENOUGH FOR LOWER 60S IN THE VALLEYS. THIS RIDGE PROBABLY WILL NOT BE STRONG TO KEEP CLOUD COVER TO OUR NORTH...AND THE NORTH COAST MAY GET BRUSHED WITH SOME RAIN OR DRIZZLE TUE/TUE NIGHT. THE RIDGE COLLAPSES WEDNESDAY...ALLOWING ANOTHER FRONT TO SAG SOUTH AND SPREAD RAIN INTO OUR FORECAST AREA. WEAGLE .LONG TERM...MAIN CHANGES TO THE EXTENDED FORECAST WERE TO INCREASE POPS SLIGHTLY AS IT APPEARS WE REMAIN IN A ZONAL AND PROGRESSIVE PATTERN AFTER WEDNESDAYS FRONTAL SYSTEM. THIS MEANS NEAR OR SLIGHTLY BELOW NORMAL TEMPERATURES WITH RAIN AT TIMES FOR THE LATE WEEK PERIOD. WEAGLE && .AVIATION...A MIX OF MVFR/VFR AND BREEZY CONDITIONS WILL CONTINUE ACROSS MUCH OF THE FORECAST AREA THROUGH TODAY. CONDITIONS WILL GRADUALLY RELAX BY THIS AFTERNOON AS THE AIR MASS DESTABILIZES... WITH OCCASIONAL SHOWERS BRINGING A THREAT FOR BRIEF HEAVY RAIN...SMALL HAIL AND LIGHTNING. THIS ACTIVITY SHOULD BEGIN TO WANE BY THIS EVENING. A RELATIVELY UNSTABLE AIR MASS WILL PERSIST INTO TONIGHT KEEPING MANY LOCATIONS VFR...WITH SOME PATCHY MVFR CIGS. KPDX AND APPROACHES...EXPECT PREDOMINANTLY VFR CONDITIONS THE NEXT 24 HRS. GUSTY WINDS CONTINUE THROUGH EARLY THIS AFTERNOON. THERE IS A CHANCE FOR A THUNDERSTORM TO IMPACT THE TERMINAL THIS AFTERNOON AND EARLY EVENING...BRINGING OCCASIONAL MVFR CIGS WITH IT. /27 && .MARINE...THE SYSTEM THAT BROUGHT STRONG WINDS TO THE COASTAL WATERS HAS NOW PUSHED FURTHER INLAND THIS MORNING. WESTERLY WINDS WILL CONTINUE IN THE 20 TO 25 KT RANGE BEHIND THE FRONT THROUGH LATE TONIGHT...BUT MAY SEE BRIEF PERIODS THIS MORNING WHERE WINDS DROP BELOW CRITERIA. SEAS WILL ALSO REMAIN AROUND 10 TO 12 FT TODAY AND TONIGHT. HIGH PRESSURE WILL THEN BEGIN TO BUILD INTO THE REGION MONDAY... CAUSING WINDS TO SUBSIDE AND SEAS TO RELAX. THIS SHOULD CONTINUE UNTIL MIDDAY TUESDAY WHEN A WEAKENING FRONT BRINGS A BURST OF 20 TO 25 KT WINDS TO PRIMARILY THE NORTHERN WATERS. ANOTHER STORM SYSTEM WILL SLIDE BY TO OUR NORTH WEDNESDAY...CAUSING SOUTH WINDS TO INCREASE ONCE AGAIN AND SEAS TO BRIEFLY POP UP NEAR 10 FT. HIGH PRESSURE SHOULD THEN CAUSE WINDS AND SEAS TO RELAX LATE IN THE WORK WEEK. /NEUMAN /27 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...WINTER WEATHER ADVISORY UNTIL 11 PM PDT THIS EVENING FOR CASCADES IN LANE COUNTY-NORTHERN OREGON CASCADES. WA...WINTER WEATHER ADVISORY UNTIL 11 PM PDT THIS EVENING FOR SOUTH WASHINGTON CASCADES. PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 11 AM PDT MONDAY FOR COASTAL WATERS FROM CAPE SHOALWATER TO FLORENCE OUT 60 NM. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM PDT MONDAY FOR COASTAL WATERS FROM CAPE SHOALWATER TO FLORENCE OUT 60 NM. SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 5 AM PDT MONDAY. && MORE WEATHER INFORMATION ONLINE AT... HTTP://WEATHER.GOV/PORTLAND THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
639 AM CDT SUN APR 7 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 342 AM CDT SUN APR 7 2013 CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED UPPER TROUGHING APPROACHING THE PACIFIC NORTHWEST...WEAK RIDGING OVER THE NORTHERN U.S. ROCKIES INTO THE DAKOTAS...AND A SHORTWAVE TROUGH OVER EASTERN WISCONSIN. ALSO OF NOTE ON WATER VAPOR WERE A PAIR OF SHORTWAVES MOVING THROUGH THE WEAK RIDGING...ONE IN SOUTH CENTRAL WYOMING AND THE OTHER IN NORTHWEST COLORADO. THE FORECAST AREA LIES IN SUBSIDENCE IN THE WAKE OF THE EASTERN WISCONSIN SHORTWAVE TROUGH...SEEN AS AN INVERSION BETWEEN 775 AND 850MB ON THE 00Z MPX SOUNDING. THIS INVERSION WAS ALSO SATURATED... REFLECTED TOO BY PLENTY OF STRATUS CLOUDS ON 11-3.9UM IMAGERY FROM THE EASTERN DAKOTAS INTO THE FORECAST AREA. COOLER AIR HAS BEEN FILTERING IN BEHIND THE SHORTWAVE AS WELL WITH 850MB TEMPS NOW DOWN TO +2 TO -3C ACROSS THE FORECAST AREA PER RAP ANALYSIS...COLDEST OVER CENTRAL WISCONSIN. AT THE SURFACE...HIGH PRESSURE WAS SEEN DROPPING SOUTH INTO WESTERN MINNESOTA...IN THE WAKE OF LOW PRESSURE OVER NORTHERN LAKE MICHIGAN AND ITS COLD FRONT WHICH EXTENDS SOUTHWEST TO KANSAS CITY. A PATTERN CHANGE IS FORECAST TO OCCUR ALOFT DURING THE NEXT 24 HOURS AS THE UPPER TROUGH SEEN OFF THE PACIFIC NORTHWEST SHARPLY DIGS SOUTH INTO CALIFORNIA AND NEVADA. IN RESPONSE...RIDGING WILL BUILD DOWNSTREAM...ADJUSTING THE UPPER LEVEL FLOW TO SOUTHWESTERLY OVER THE FORECAST AREA. THIS MEANS THAT THE RECENT LOW LEVEL COLD ADVECTION WILL COME TO AN END SHORTLY...WITH WARM ADVECTION PROGGED TO BEGIN BETWEEN 12-18Z TODAY AND CONTINUE THROUGH TONIGHT. IN ADDITION...MODELS HAVE BEEN CONSISTENT IN SHOWING THE PAIR OF SHORTWAVES SEEN IN WYOMING AND COLORADO TO AFFECT THE FORECAST AREA LATE TONIGHT AS THEY RIDE THROUGH THE SOUTHWEST FLOW. THE FIRST TWO ISSUES FOR THE SHORT TERM PERIOD ARE THE CLOUDS AND HIGH TEMPERATURES TODAY. THE PRESENT STRATUS DECK DOES HAVE SOME HOLES IN IT ON ITS SOUTHERN SIDE. THESE HOLES SHOULD EXPAND THROUGH THE MORNING AS DIURNAL MIXING COMMENCES. 07.00Z NAM LOW LEVEL RH FIELDS...WHICH GENERALLY TEND PESSIMISTIC...ALSO SUGGEST THAT THE STRATUS DECK WILL MOSTLY MIX OUT BY 18Z SOUTH OF US HIGHWAY 10. LATER IN THE AFTERNOON...SAY 21Z AND AFTER...MID AND HIGH CLOUDS CURRENTLY SPREADING INTO THE PLAINS STATES ARE PROGGED TO MOVE INTO THE FORECAST AREA. THUS WE SHOULD SEE AT LEAST A FEW HOURS OF MOSTLY SUNNY SKIES TODAY. WITH 850MB TEMPS CLIMBING TO 0C NORTH AND 6C SOUTH BY 18Z...ANTICIPATING THAT MOST LOCATIONS MINUS NORTH OF HIGHWAY 10 WHERE MORE CLOUDS AND SNOW EXIST WILL CLIMB INTO THE 50S. WARMEST TEMPERATURES...APPROACHING 60...ARE EXPECTED IN THE FAR SOUTH. THE NEXT ISSUE FOR THE SHORT TERM PERIOD IS THE POTENTIAL FOR PRECIPITATION VERY LATE THIS AFTERNOON INTO TONIGHT...DUE TO THE WARM ADVECTION PATTERN AND THE APPROACH OF THE PAIR OF SHORTWAVES. THE 07.00Z GFS/06.12Z ECMWF ALREADY SHOW HINTS OF WARM ADVECTION / ISENTROPICALLY INDUCED PRECIPITATION AFFECTING FAR WESTERN PORTIONS OF THE FORECAST AREA BETWEEN 21-00Z TODAY. THINKING THIS MIGHT BE A BIT FAST...WITH THE 07.00Z NAM/REGIONAL CANADIAN/HIRES-ARW AND 07.03Z SREF ALL SLOWER. THUS...PLAN ON KEEPING CONDITIONS DRY TIL 00Z. AS WE HEAD THROUGH TONIGHT...THERE IS A STRONG CONSENSUS AMONGST ALL MODEL GUIDANCE OF A PRECIPITATION SPLIT. THE NORTHERN AREA TRACKS FROM NORTHWEST IA/SOUTHERN MN INTO NORTHWEST WISCONSIN. THE SOUTHERN AREA TRACKS FROM NORTHERN MISSOURI INTO SOUTHEAST IA AND NORTHWEST IL. THIS SPLIT APPEARS TO BE A RESULT OF HOW THE PAIR OF SHORTWAVES APPROACHING THE FORECAST AREA LATE TONIGHT INTERACT WITH THE ISENTROPIC LIFT PATTERN IN PLACE. 850MB MOISTURE TRANSPORT FIELDS SHOW THE SPLIT INTERACTION WITH THE ISENTROPIC LIFT PATTERN NICELY. IN ADDITION...THERE ARE OTHER SUPPORTING FEATURES. FOR EXAMPLE...THE NORTHERN AREA BECOMES INFLUENECED BY A DEVELOPING AND STRENGTHENING UPPER JET STREAK OVER UPPER MICHIGAN...PLACING IT IN THE FAVORABLE RIGHT ENTRANCE REGION. MEANWHILE...THE SOUTHERN AREA HAS A STRONG LOW TO MID- LEVEL FRONTOGENESIS FEATURE ALONG THE PRESENT COLD FRONT NEAR I-70...WHICH FOR ALL INTENSIVE PUPROSES TURNS INTO A STATIONARY BOUNDARY. SO FOR THE FORECAST...THIS WELL AGREED UPON SPLIT PRECIPITATION SCENARIO POSES A PROBLEM FROM WHAT WE HAD GOING PREVIOUSLY. HAVE ADJUSTED PRECIPITATION CHANCES AND QPF QUITE A BIT LOWER SOUTH OF I-90...SINCE THIS AREA WILL BE ON THE SUBSIDENT SIDE OF THE F-GEN CIRCULATION. NOTE THAT MODELS LIKE THE 07.00Z GFS/REGIONAL CANADIAN EVEN SUGGEST THAT SOME LOCATIONS ACROSS NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN COULD END UP DRY. REGARDING PRECIPITATION TYPE...ALL OF IT SHOULD FALL AS RAIN WITH WET-BULB ZERO HEIGHTS PROGGED WELL ABOVE 2000 FT. THE PREVIOUS FORECAST INTRODUCED A CHANCE FOR THUNDER AND THIS STILL LOOKS REASONABLE AFTER MIDNIGHT...WITH POTENTIAL FOR A FEW HUNDERED J/KG OF SKINNY CAPE LIFTED FROM 850MB. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 342 AM CDT SUN APR 7 2013 OVERALL MUCH OF THE LONG TERM PERIOD LOOKS ACTIVE...THANKS TO THAT TROUGH DIGGING INTO CALIFORNIA AND NEVADA TONIGHT. QUITE A FEW DETAILS TO NOTE. ON MONDAY...THE PAIR OF SHORTWAVES ARE PROGGED TO SHIFT EAST INTO MICHIGAN DURING THE AFTERNOON...TAKING THE BULK OF THE SPLIT PRECIPITATION TONIGHT WITH THEM. HOWEVER...THE STORY DOES NOT END THERE. THE FOCUS TURNS TO THE FRONTAL BOUNDARY NEAR I-70...WHICH BY ALL MODELS IS SUGGESTED TO LIFT NORTH INTO CENTRAL AND PERHAPS NORTHERN IA DURING THE AFTERNOON. THE LIFTING NORTH IS A RESULT OF THE UPPER TROUGHING DEEPENING AND DIGGING INTO THE FOUR CORNERS REGION...ENHANCING THE WARM ADVECTION DOWNSTREAM. THE 07.00Z REGIONAL CANADIAN AND NAM SUGGEST THERE IS POTENTIAL FOR SURFACE BASED CONVECTION TO FIRE ON THIS FRONT. THE 07.00Z GFS...ON THE OTHER HAND...HAS A FARTHER SOUTH FRONT AND KEEPS THINGS MORE CAPPED. HOWEVER...ALL THREE MODELS INCLUDING THE 06.12Z ECMWF DEPICT POTENTIAL FOR FRONTOGENETICALY INDUCED PRECIPITATION NORTH OF THE FRONTAL BOUNDARY. THUS...A NEED CONTINUES FOR CHANCES OF SHOWERS ALONG WITH THE THUNDERSTORM MENTION IN THE EVENT THE REGIONAL CANADIAN/NAM PAN OUT. IF THE REGIONAL CANADIAN/NAM PAN OUT... CERTAINLY COULD NOT RULE OUT SOME SEVERE POTENTIAL GIVEN 0-6 KM SHEAR UPWARS OF 45-50 KT. HOWEVER...IT SEEMS LIKE THE BETTER INSTABILITY IS WEST OF THE FORECAST AREA...THUS KEEPING THE BULK OF THE SEVERE POTENTIAL TO THE WEST. SPC DAY 2 SEVERE PROBABILITIES DEPICT THIS AS WELL. DEFINITELY SOMETHING TO KEEP AN EYE ON....THOUGH. TEMPERATURE FORECAST IS TRICKY AS IT DEPENDS ON THE FRONTAL POSITION. A NAM/REGIONAL CANADIAN OR EVEN ECMWF SOLUTION WOULD ALLOW FOR HIGHS IN THE 60S TO POSSIBLY 70 ALONG/SOUTH OF I-90. THE GFS IS A LITTLE COOLER BUT STILL HAS HIGHS IN THE 60S SOUTH OF I-90. RAISED HIGHS 5 DEGREES OR SO TO COME BETTER IN AGREEMENT WITH ALL 07.00Z GUIDANCE...BUT THEY MAY NEED TO BE RAISED MORE... ESPECIALLY IF MORE SUN OCCURS IN THE AFTERNOON. THINGS GET MORE INTERESTING HEADING INTO THE MONDAY NIGHT THROUGH THURSDAY TIME PERIOD. DURING THIS PERIOD...ALL MODELS HAVE THE DEEP UPPER TROUGH OVER THE FOUR CORNERS SLOWLY LIFTING TO THE EAST-NORTHEAST. MEANWHILE...AT THE SAME TIME THERE IS A DEEP UPPER TROUGH HANGING AROUND THE HUDSON BAY INTO NORTHERN ONTARIO AREA... HELPING TO HOLD AN UPPER JET STREAK IN PLACE OVER THE NORTHERN GREAT LAKES. THIS MEANS THE FORECAST AREA IS GOING TO BE PLACED IN THE FAVORABLE RIGHT ENTRANCE REGION UNTIL THE UPPER TROUGH MOVES IN. MONDAY NIGHT FOR THE MOST PART LOOKS QUIET...WITH ANY SHOWERS AND POSSIBLE THUNDERSTORMS IN THE EVENING DISSIPATING WITH LOSS OF DAYTIME HEATING. THE FRONTAL BOUNDARY...IF IT IS NEARBY...LOOKS TO SLOWLY DROP SOUTH MONDAY NIGHT FORCED BY THAT DEEP UPPER TROUGH TO OUR NORTH. IT APPEARS THERE MAY BE A MASS OF LOW LEVEL STRATUS THAT MOVES IN BEHIND THE FRONT...AND WITH LOW LEVEL FRONTOGENESIS BEHIND THE FRONT WE COULD DEAL WITH SOME LIGHT RAIN OR DRIZZLE. PRECIPITATION CHANCES DEFINITELY GO ON THE INCREASE FROM SOUTHWEST TO NORTHEAST THROUGH THE DAY TUESDAY AND INTO TUESDAY NIGHT...IN RESPONSE TO ISENTROPIC LIFT STRENGTHENING DOWNSTREAM OF THE UPPER TROUGH PUSHING TO THE EAST-NORTHEAST. SOME CONCERN FOR SOME HEAVIER RAIN TUESDAY NIGHT...ESPECIALLY ACROSS THE SOUTH...AS PRECIPITABLE WATER VALUES INCREASE OVER 1 INCH AND SOME WEAK ELEVATED INSTABILITY MOVES IN FOR THUNDERSTORMS. RAISED BOTH PRECIPITATION CHANCES AND QPF FOR TUESDAY AND ESPECIALLY TUESDAY NIGHT GIVEN THE STRONG SIGNAL AMONGST THE 07.00Z ECMWF/GFS/CANADIAN MODELS. FROM WEDNESDAY INTO THURSDAY...THE CORE OF THE UPPER TROUGH IS PROGGED TO SLOWLY APPROACH THE FORECAST AREA. AS THIS OCCURS...THE FORECAST AREA EVENTUALLY ENDS UP ON THE NORTHWEST / COLD SIDE OF A SURFACE LOW TRACKING TO OUR SOUTH...PLACING THE AREA INTO THE TROWAL AND COLD CONVEYOR BELT REGION. GIVEN THE GOOD MODEL AGREEMENT AGAIN...RAISED PRECIPITATION CHANCES UP DURING THIS PERIOD. IN ADDITION...WILL HAVE TO WATCH FOR SOME SNOW ACCUMULATIONS COME WEDNESDAY NIGHT AND THURSDAY AS 850MB TEMPS DROP TO -4 TO -8C BY 12Z THURSDAY. IT SHOULD BE NOTED THAT THE 07.00Z NAM IS AN OUTLIER SOLUTION TO THE ABOVE SCENARIO...PARTICULARLY FOR TUESDAY THROUGH WEDNESDAY...SINCE IT EJECTS THE CORE OF THE SOUTHWESTERN TROUGH MUCH QUICKER AND LIFTS IT FARTHER NORTH. THE NAM WAS DISCOUNTED GIVEN GOOD MODEL AGREEMENT BETWEEN ALL OTHER MODELS. THE 07.03Z SREF LOOKS LIKE A COMPROMISE BETWEEN THE NAM AND GFS...BUT THE SREF IS NAM-BIASED DUE TO AN OVERWHELMING AMOUNT OF NAM MEMBERS. THUS...THE SREF WAS DISCOUNTED AS WELL. LOOKING FARTHER AHEAD...GOOD MODEL AGREEMENT EXISTS AMONGST THE 07.00Z ECMWF/GFS/CANADIAN ON BRINGING COLD CANADIAN HIGH PRESSURE INTO THE AREA THURSDAY NIGHT THROUGH FRIDAY NIGHT. THIS SHOULD HELP DRY THINGS OUT. LEFT A CONSENUS 20 PERCENT CHANCE OF PRECIPITATION IN THURSDAY NIGHT...BUT THIS PERIOD MAY EVENTUALLY END UP DRY. WILL NEED TO WATCH SOME OF THE LOW TEMPERATURES TOO FOR BOTH THURSDAY NIGHT AND FRIDAY NIGHT...DEPENDING ON HOW MUCH FRESH SNOW WE PICK UP AND FOR FRIDAY NIGHT HOW MUCH IS STILL ON THE GROUND. A WARM ADVECTION PATTERN SETS UP FOR SATURDAY AHEAD OF NEW TROUGHING DROPPING INTO THE NORTHERN ROCKIES. FOLLOWED THE CONSENSUS HERE OF BRINGING SOME 20-30 PERCENT CHANCES OF PRECIPITATION ACROSS THE AREA ON SATURDAY. NEED TO MAINTAIN A RAIN/SNOW MIX BECAUSE 850MB TEMPS ARE STILL SLOW TO WARM...ESPECIALLY IN THE ECMWF WHERE IT KEEPS THEM BELOW 0C THROUGH 00Z SUNDAY. && .AVIATION...TODAY AND TONIGHT 638 AM CDT SUN APR 7 2013 BUFKIT SOUNDINGS SUGGEST THAT THE MVRF CLOUDS WILL LINGER THROUGH THIS MORNING...AND THEN QUICKLY DISSIPATE BETWEEN 07.18Z AND 07.21Z. A 5 TO 10K CLOUD DECK WILL MOVE BACK INTO THE AREA BETWEEN 07.23Z AND 08.03Z AND THEN PERSIST THROUGH THE REMAINDER OF THE NIGHT AS A LOW PRESSURE SYSTEM PASSES TO THE NORTHWEST OF THE TAF SITES. SCATTERED SHOWERS WILL MOVE INTO THE AREA AFTER 08.06Z...BUT SHOULD NOT AFFECT THE VISIBILITIES TOO MUCH. && .HYDROLOGY... ISSUED AT 342 AM CDT SUN APR 7 2013 RIVER STATUS... THE TREMPEALEAU RIVER NEAR DODGE WILL REMAIN ABOVE FLOOD STAGE AND ALLOW FOR MINOR FLOODING TO CONTINUE THROUGH MONDAY MORNING. MEANWHILE ON THE BLACK...ANOTHER BRIEF ICE JAM LOOKS LIKE IT MAY HAVE FORMED AROUND NEILLSVILLE...WITH A SPIKE UP OF 4 FEET BUT STILL WELL WITHIN THE RIVER BANK. DOWNSTREAM...SO FAR THE BLACK REMAINS WITHIN THE RIVER BANK. SNOW PACK... RECENT COOPERATIVE OBSERVER REPORTS SHOW SNOW PACK IS MAINLY ALONG AND NORTHEAST OF THE INTERSTATE 94 CORRIDOR WITH 2 TO 7 INCHES OF SNOW DEPTH IN PLACES. THE DEEPEST SNOW PACK IS OVER THE NORTHERN MOST PARTS OF TAYLOR WHERE AROUND A FOOT OF SNOW REMAINS ON THE GROUND. SNOW WATER EQUIVALENT OF 1 TO 2 INCHES IS MAINLY NORTH OF THE INTERSTATE 94 CORRIDOR WITH THE GREATEST SNOW WATER EQUIVALENT OF 2 TO 4 INCHES IN NORTHERN TAYLOR COUNTY. RAINFALL... LESS RAINFALL IS ANTICIPATED TONIGHT INTO MONDAY THAN PREVIOUSLY EXPECTED...WITH UPWARDS OF 1/4 TO 1/2 INCH NORTH OF I-90 AND LESS THAN A 1/4 INCH TO THE SOUTH. WILL STILL NEED TO WATCH TUESDAY THROUGH WEDNESDAY...THOUGH. BY WEDNESDAY MORNING...CURRENTLY ANTICIPATING AMOUNTS BETWEEN 3/4 INCH AND 1.25 INCHES SOUTH OF HIGHWAY 10 TO LESS THAN A 1/2 INCH TO THE NORTH. IF THE SYSTEM BRINGING THIS RAIN SHIFTS FARTHER NORTH...THE HEAVY RAIN AREA WILL SHIFT NORTH AS WELL...PLACING IT WHERE RAIN IS NOT NEEDED. TEMPERATURES... HIGHS TODAY ARE GOING TO BE COOLER...IN THE THE MIDDLE 40S/AROUND 50 NORTH OF I-94 AND IN THE 50S SOUTH OF THERE. WARMER CONDITIONS LOOK ON TAP FOR MONDAY...WITH MOSTLY 50S NORTH OF I-94 AND 60S SOUTH. TEMPERATURES THEN COOL INTO THE 40S FOR TUESDAY AND WEDNESDAY AND POSSIBLY STRUGGLE TO GET TO 40 BY THURSDAY. THE TEMPERATURE MAY NOT MATTER IN A FEW DAYS AS MOST OF THE SNOW PACK MAY BE GONE...UNTIL POTENTIALL A SMALL SNOW PACK RE-ESTABLISHES ITSELF THURSDAY MORNING. FROST DEPTH... AS OF APRIL 4TH...FROST DEPTHS //WHICH ARE OBSERVED EVERY MONDAY AND THURSDAY//ACROSS THE AREA REMAIN DEEP...AVERAGING AROUND 1 FOOT TO 1 1/2 FEET SOUTH OF I-90...AND UP TO 3 FEET ACROSS PORTIONS OF NORTH CENTRAL WISCONSIN. THIS FROST WILL ACT TO ENHANCE RUNOFF OF SNOW MELT AND PRECIPITATION INTO STREAMS AND RIVERS. SUMMARY... MAIN CONCERN FOR FLOODING REMAINS ALONG THE TREMPEALEAU AND BLACK RIVERS AS SNOW MELT CONTINUES...ALONG WITH THE PERIODS OF RAINFALL TONIGHT INTO MONDAY AS WELL AS TUESDAY THROUGH WEDNESDAY. HAVE A HYDROLOGIC OUTLOOK PRODUCT OUT TO HEIGHTEN THIS AWARENESS. ALTHOUGH THE TUESDAY INTO WEDNESDAY MODERATE TO HEAVY RAIN IS FORECAST MAINLY SOUTH OF I-90...CURRENTLY THINKING THAT THE RIVERS SHOULD BE ABLE TO ABSORB IT. A QUICK MODEL OF THE TURKEY RIVER AT GARBER USING THE FORECAST QPF WOULD BRING THE RIVER ABOVE ACTION STAGE BUT NOT TO FLOOD. THUS...DID NOT EXPAND THE HYDROLOGIC OUTLOOK SOUTH. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...BOYNE HYDROLOGY...AJ
AREA FORECAST DISCUSSION
NWS ALBANY NY
423 PM EDT SUN APR 7 2013 .SYNOPSIS... LOW PRESSURE WILL CONTINUE TO TRACK NORTHEAST ACROSS THE SAINT LAWRENCE VALLEY TONIGHT. A BAND OF SHOWERS WILL TRACK ACROSS THE REGION INTO THIS EARLY EVENING...THEN THE WINDS AND THE SHOWERS WILL DIMINISH. A DRY START TO THE WORK WEEK BEFORE ANOTHER LOW PRESSURE SYSTEM APPROACHES MONDAY NIGHT WITH ANOTHER CHANCE FOR SHOWERS. RATHER UNSETTLED CONDITIONS ARE EXPECTED FOR THE REMAINDER OF THE WEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... H2O VAPOR LOOP SHOWS A RATHER STRONG UPPER LOW TRACKING NORTHEAST ACROSS THE ST LAWRENCE VALLEY WITH AN IMPRESSIVE SURFACE PRESSURE GRADIENT IN PLACE ACROSS EASTERN NY. THE VWP FROM THE WSR88D SHOWS WINDS WITHIN THE BOUNDARY LAYER ARE AROUND 40KTS. WITH FUNNELING UP THE HUDSON VALLEY...WIND SPEEDS HAVE INCREASED WITH SEVERAL REPORTING STATIONS GUSTING INTO THE LOW-MID 40MPH RANGE. THE ADDITIONAL INSOLATION WE RECEIVED ALSO ASSISTED WITH MOMENTUM TRANSFER TODAY ALONG WITH TEMPERATURES CLIMBING A COUPLE DEGREES OF FORECAST. A BAND OF SHOWERS ALONG THE COLD FRONT HAS DEVELOPED AND WE EVEN HAD A FEW LIGHTNING STRIKES PER THE NLDN ACROSS THE ADIRONDACKS. WHILE THE LIGHTNING HAS DIMINISHED...THE BAND OF SHOWERS HAS INCREASED IN COVERAGE AND FORWARD MOMENTUM THE PAST COUPLE OF HOURS. THE LATEST HRRR REFLECTIVITY FORECASTS SUGGEST THIS LEADING EDGE OF PRECIP WILL DIMINISH WITH ANOTHER RENEW AREA OF SHOWERS ACROSS LAKE ONTARIO AND WESTERN NY EXPECTED TOWARD THIS EARLY EVENING AND QUICKLY MOVE ACROSS MAINLY EASTERN NY. WE WILL KEEP POPS INTO CHC-SCT CATEGORY THROUGH THE REMAINDER OF TODAY AND INTO THE EVENING. COLD ADVECTION WILL COMMENCE IN THE WAKE OF FROPA AS H850 TEMPS SETTLE BACK INTO THE LOWER SINGLE DIGITS. WESTERLY WINDS SHOULD KEEP SOME UPSLOPE CLOUDS...ESPECIALLY ACROSS THE WESTERN NEW ENGLAND COUNTIES. AS FOR WINDS...COULD SEE SOME SLIGHT ENHANCEMENT THRU THE MOHAWK RIVER LATER THIS EVENING...BUT EXPECTATIONS ARE FOR THE SURFACE RIDGE TO BUILD IN AND RELAX THE GRADIENT AND THOSE WINDS. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/... MONDAY...INCREASING CONFIDENCE THAT THE RIDGE BOTH ALOFT AND THE SURFACE WILL CREST OVER THE REGION FOR A NICE START TO THE WORK WEEK. H850 TEMPS CLIMB A COUPLE OF DEGREES THROUGH THE DAY AND COINCIDING WITH MIXING LAYER HEIGHTS BETWEEN H850-H900...WE SHOULD BE ABLE TO OBTAIN AFTERNOON HIGHS L-M60S FOR VALLEY LOCATIONS AND 50S ELSEWHERE. MONDAY NIGHT...INCREASING LOW LEVEL JET ACROSS THE LOWER AND MID MISSISSIPPI RIVER VALLEY ALONG WITH A TIGHTENING BAROCLINIC ZONE WILL LIKELY RESULT IN AN ORGANIZED CONVECTIVE EPISODE THAT WILL TRACK TOWARD THE UPPER OHIO VALLEY AND LOWER GREAT LAKES REGION MONDAY NIGHT. TRENDS FROM THE NCEP MODEL SUITE AND INTERNATIONAL GUIDANCE ALL SUGGEST THIS SYSTEM TO TRACK ACROSS THE REGION DURING THE EVENING AND EARLY OVERNIGHT PERIOD. AS PREVIOUS MENTIONED IN THE EARLIER AFD/S...MID LEVEL INSTABILITY PER THE SHOWALTERS DROP TO OR BELOW 0C TO CONTINUE TO THE MENTION OF THUNDER IN THE FORECAST. AT THIS TIME...SEEMS THE RAINFALL AMOUNTS OF ONE QUARTER TO ONE HALF OF AN INCH ARE TO BE EXPECTED /SEE HYDRO SECTION BELOW/. TUESDAY...THE STRENGTH OF THIS CONVECTIVE SYSTEM MAY JUST BE ENOUGH TO ALLOW FOR INCREASED SUBSIDENCE FOR A RATHER NICE DAY IN THE WAKE OF THE RAINFALL. WE WILL DECREASE POPS AND INCREASE THE POTENTIAL FOR PARTIAL SUNSHINE. SINCE WE SHOULD BE RATHER MILD START TO THE DAY...WE COULD SEE OUR FIRST REAL RUN AT 70F FOR THE CAPITAL REGION WITH HIGHER CONFIDENCE OF 70S INTO THE MID HUDSON VALLEY AND PORTIONS OF LITCHFIELD COUNTY. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... MODEL CONSENSUS IS BETTER DURING THIS TIME FRAME COMPARED TO EARLIER RUNS. ALL INDICATE AN UNSETTLED PATTERN DURING MUCH OF THIS TIME FRAME AS A STRONG FRONTAL STALLS NEAR THE AREA. THE 12Z OPERATIONAL GFS CONTINUES TO HAVE THIS FRONT STALLING THE FURTHEST NORTH...CLOSE TO JUST NORTH OF INTERSTATE 90. THE 12Z CANADIAN MODEL STALLED THE FRONT A LITTLE FURTHER SOUTH. THE 1Z EUROPEAN WAS STILL THE FURTHEST SOUTH...STALLING THE FRONT CLOSER TO THE MASON DIXON LINE. WE HAVE LEANED WITH THE EUROPEAN SOLUTION WHICH HAPPENED TO THE WEATHER PREDICTION CENTER (WPC) SOLUTION AS WELL. TUESDAY NIGHT MOST MODELS FORECAST SOME SORT OF MESO-SCALE COMPLEX (MCS) WORKING THROUGH THE AREA. THE 12Z GFS AND 12Z EUROPEAN FORECAST MODELS INDICATE THIS WOULD TRACK FROM I-90 SOUTH...WHILE THE CANADIAN MODEL INDICATED IT WOULD TRAVEL FURTHER NORTH. FOR NOW...JUST WENT WITH 40 POPS OF SHOWERS EVERYWHERE ACROSS THE REGION. OVERNIGHT LOWS WILL BE IN THE MID TO UPPER 30S NORTH...40S MOST OTHER PLACES. WEDNESDAY LOOKS AS IF IT MIGHT BE THE "DRIEST" OF THE PERIOD IN THAT WE SHOULD BETWEEN AN EXISTING MCS AND PERHAPS ANOTHER LINE OF SHOWERS APPROACHING AHEAD OF A COLD FRONT. DUE TO LACK OF CONFIDENCE IN TIMING...WE CANNOT RULE OUT A STRAY SHOWER OR TWO...BUT MUCH OF THE DAY COULD BE RAINFREE AND MILD WITH TEMPERATURES MAINLY IN THE 60S...EXCEPT 50S ACROSS THE ADIRONDACK PARK AND SOUTHERN GREENS. A THUNDERSTORM CANNOT BE COMPLETELY RULED OUT (MENTIONED SLIGHT CHANCE OF THUNDERSTORMS). WEDNESDAY NIGHT...THE AFOREMENTIONED COLD FRONT LOOKS TO MOVE THROUGH BRINGING AT LEAST SOME SCATTERED SHOWERS. TEMPERATURES LOOK TO REMAIN MILD MAINLY IN THE 50S SOUTH...40S NORTH. THEN FRONT LOOKS TO STALL...AGAIN PROBABLY SOUTH OF OUR REGION...SOMETIME THURSDAY THROUGH FRIDAY. WAVES OF LOW PRESSURE WILL LIKELY RIPPLE ALONG THIS FRONT...IMPOSSIBLE TO CORRECTLY TIME THIS FAR OUT. WE MIGHT SQUEAK OUT ANOTHER MILD DAY THURSDAY WITH HIGHS IN THE 60S FROM THE CAPITAL DISTRICT SOUTH...50S FURTHER NORTH. TEMPERATURES THEN COOL DOWN TO THE 40S THURSDAY NIGHT (30S NORTH). IT WILL TURN COOLER FRIDAY WITH HIGHS ONLY 50-55 ALBANY SOUTH...40S AND EVEN SOME UPPER 30S FURTHER TO THE NORTH. IT DOES APPEAR A MORE SIGNIFICANT AREA OF LOW PRESSURE WILL RIDE THE FRONT ON FRIDAY...BRINGING THE BEST CHANCE OF A SOAKING RAIN. THE 12Z EUROPEAN FORECAST MODEL STILL INSIST IT COULD BE COULD ENOUGH FOR SOME MIXED PRECIPITATION TO FALL LATE FRIDAY INTO FRIDAY NIGHT FROM THE CAPITAL DISTRICT NORTHWARD AS SHALLOW COLD AIR WEDGES IN FROM THE NORTH THANKS TO A STRONG AGEOSTROPHIC NORTHERLY FLOW. H925 TEMPERATURES ON THAT MODEL DROP TO BELOW 0Z (FREEZING) WHILE H850 ARE INITIALLY WELL ABOVE 0C...BUT EVENTUALLY FALL BELOW FREEZING LATER FRIDAY NIGHT. FOR NOW...WE HAVE MAINLY RAIN IN THE GRIDS...BUT DO MENTION A POSSIBLE CHANGEOVER TO SNOW MOST PLACES FRIDAY NIGHT. BEING THIS EVENT IS STILL NEARLY A WEEK WAY...WE WILL HAVE PLENTY OF TIME TO MONITOR THE LATEST TRENDS. THE WHOLE DISTURBANCE SHOULD LIFT OUT TO OUR NORTHEAST SATURDAY. IN ITS WAKE...A CHILLY BREEZY DAY AWAITS US SATURDAY...WITH SOME MODERATION BY SUNDAY. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... VFR CONDITIONS AND GUSTY WINDS WILL PREVAIL THROUGH THE REMAINDER OF THE AFTERNOON. A WARM FRONT WILL APPROACH THE AREA FROM THE SOUTH...LOWERING CEILINGS CLOSE TO MVFR LEVELS...BEFORE HIGH PRESSURE BUILDS ACROSS THE REGION FOR MONDAY. THIS AFTERNOON...GUSTY SOUTHERLY WINDS WILL CONTINUE THROUGH THE REMAINDER OF THE AFTERNOON AS TERRAIN CHANNELING AND DEEP BOUNDARY LAYER MIXING CONTINUE WITH NOW INCREASED DAYTIME HEATING DUE TO CLEARING AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM PER THE LATEST VISIBLE SATELLITE IMAGERY. CLOUD COVER WILL GRADUALLY FILL IN LATE IN THE AFTERNOON WITH SCATTERED SHOWERS DEVELOPING AS WELL. HOWEVER CONFIDENCE REMAINS LOW REGARDING THE AREAL COVERAGE OF THESE SHOWERS...SO HAVE MENTIONED JUST VCSH IN THE TAFS. TONIGHT INTO MONDAY...AS A LOW PRESSURE SYSTEM AND ITS ASSOCIATED BOUNDARIES MOVE ACROSS THE REGION TONIGHT...CLOUD COVER WILL CONTINUE TO INCREASE WITH LOWERED CEILINGS. MVFR CEILINGS WILL BE POSSIBLE AT KPSF TOWARDS DAYBREAK...BUT SHOULD REMAIN AT VFR LEVELS AT KGFL/KALB/KPOU. HIGH PRESSURE WILL BUILD IN ACROSS THE REGION FOR MONDAY...ALLOWING SKIES TO CLEAR BY MONDAY AFTERNOON. WINDS WILL DIMINISH THROUGH THE OVERNIGHT AND SHIFT WESTERLY TO GENERALLY 5-10 KNOTS. OUTLOOK... MON NIGHT-THU....VFR/MVFR CHC SHOWERS. && .FIRE WEATHER... THE COLD FRONT WILL MOVE THROUGH TONIGHT WITH THE SHOWERS ENDING...AND THE RH VALUES INCREASING TO 75 TO 95 PERCENT WITH THE WINDS SHIFTING TO THE WEST NORTHWEST AT 5 TO 15 MPH...WITH A FEW HIGHER GUSTS INTO THE MOHAWK VALLEY...CAPITAL REGION AND BERKSHIRES THIS EVENING. HIGH PRESSURE WILL BRING DRY WEATHER ON MONDAY WITH MUCH LIGHTER WINDS. THE RH VALUES WILL DROP TO 30 TO 45 PERCENT BY THE MID TO LATE AFTERNOON. && .HYDROLOGY... NO WIDESPREAD HYDROLOGY PROBLEMS ARE EXPECTED AT THIS TIME...HOWEVER THERE IS MUCH UNCERTAINTY IN THE FORECAST AS WE HEAD THROUGH THE WEEK WITH REGARDS TO PRECIPITATION AND THE AMOUNTS OF SNOWMELT THAT WILL OCCUR. THE WEATHER WILL BE UNSETTLED MUCH OF THE WEEK. A CONVECTIVE COMPLEX IS EXPECTED TO IMPACT THE REGION MONDAY NIGHT. AT THIS TIME...RAINFALL AMOUNTS OF ONE QUARTER TO ONE HALF AN INCH ARE EXPECTED. COMBINE THAT WITH MILD TEMPERATURES SHOULD RESULT WITH AN INCREASE WATER FLOWS INTO AREA RIVERS AND STREAMS. AT THIS TIME...EXPECTATIONS ARE FOR WITHIN BANK WATER RISES. TEMPERATURES ARE EXPECTED TO WARM TO ABOVE NORMAL ESPECIALLY ON TUESDAY WITH A RETURN TO MORE SEASONABLE READINGS LATER IN THE WEEK. THE DEPARTURES FROM NORMAL ARE NOT EXPECTED TO BE AS PRONOUNCED ACROSS THE HIGHER TERRAIN WHERE THE SNOWPACK IS...PLUS TEMPERATURES AT NIGHT ARE EXPECTED TO COOL DOWN ENOUGH TO SLOW THE SNOWMELT. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...RED FLAG WARNING UNTIL 8 PM EDT THIS EVENING FOR CTZ001-013. NY...RED FLAG WARNING UNTIL 8 PM EDT THIS EVENING FOR NYZ038>041- 043-048>050-052>054-059>061-064>066-083-084. WIND ADVISORY UNTIL 6 PM EDT THIS EVENING FOR NYZ041>043-049- 050-052-053-059-060-083-084. MA...NONE. VT...NONE. && $$ SYNOPSIS...BGM NEAR TERM...BGM SHORT TERM...BGM LONG TERM...HWJIV AVIATION...IRL FIRE WEATHER...BGM HYDROLOGY...BGM
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
305 PM EDT SUN APR 7 2013 .SYNOPSIS... 19Z WATER VAPOR AND H4 RAP ANALYSIS SHOW AN UNAMPLIFIED UPPER LEVEL PATTERN IN PLACE OVER THE CONUS OUTSIDE OF A FEW MINOR SHORTWAVE "KINKS" IN THE FLOW. ZONAL FLOW IS IN PLACE OVER THE NORTHERN GULF COAST AND FLORIDA PENINSULA AND WILL HOLD FOR AT LEAST THE NEXT 24 HOURS. ONE VERY MINOR IMPULSE WITHIN THE ZONAL FLOW IS LOCATED OVER THE EASTERN GULF AND WILL PASS OVER THIS EVENING/TONIGHT WITH LITTLE TO NO INFLUENCE ON OUR WEATHER. AT THE SURFACE...HIGH PRESSURE EXTENDS DOWN THE EASTERN SEABOARD AND CONTINUES TO RIDGE ALL THE WAY TO THE FL PENINSULA AND CENTRAL/EASTERN GULF. GRADIENT AROUND THIS RIDGE IS PROVIDING A GENERAL EASTERLY WIND PATTERN. SIMILAR TO SATURDAY...STILL HAVE A RATHER MOIST LAYER SEEN ON TIME HEIGHT/CROSS SECTION ANALYSIS BETWEEN AROUND 950-825MB. THE 12Z KTBW SOUNDING PROFILE CONFIRMS THIS NWP FORECAST. WITH THE MOISTURE IN PLACE...DIURNAL HEATING CONTINUES TO MIX UP INTO THE COLUMN RESULTING IN A SHALLOW SCT-BKN CU FIELD EXPANDING ACROSS THE PENINSULA FROM EAST TO WEST. THIS CU FIELD WILL DISSIPATE THIS EVENING WITH THE LOSS OF DAYTIME HEATING. && .SHORT TERM (TONIGHT THROUGH TUESDAY NIGHT)... TONIGHT... QUIET AND SEASONABLE OVERNIGHT PERIOD ON TAP. MOSTLY CLEAR SKIES EXPECTED WITH TEMPERATURES DROPPING TO THE MIDDLE AND UPPER 50S FOR MANY INLAND LOCATIONS BY SUNRISE...AND HOLDING IN THE 60S AT THE COAST FROM PINELLAS COUNTY SOUTHWARD ALONG THE SUN COAST. MONDAY/MONDAY NIGHT... ZONAL FLOW PATTERN ALOFT WILL SLOWLY BEGIN TO TRANSITION TOWARD RIDGING THROUGH THE DAY...AND COMPLETE THE TRANSITION MONDAY NIGHT. AT THE SURFACE...AN EAST TO SOUTHEAST FLOW PATTERN WILL HOLD IN PLACE ON THE SOUTHERN SIDE OF A RIDGE AXIS OFF THE GA/SC COAST. EFFICIENT DIURNAL MIXING AND 800-850MB TEMPS AROUND 12C SHOULD EASILY ALLOW AFTERNOON TEMPS TO MIX OUT TO THE LOWER AND MIDDLE 80S AWAY FROM THE BEACHES. SIMILAR TO TODAY...THE STRONG TERRESTRIAL HEATING AND WEAKER AFTERNOON GRADIENT WILL ALLOW AN ONSHORE WIND COMPONENT TO DEVELOP AT THE COAST AND HOLD TEMPS DOWN IN THE 70S OFF THE SHELF WATERS. MOSTLY SUNNY SKIES TO START THE DAY WILL FILL IN WITH A SCT-BKN CU FIELD FOR A GENERALLY PARTLY CLOUDY AFTERNOON FORECAST. A SLOW INFLUX IN LOW LEVEL MOISTURE WILL CONTINUE THE RISE IN OVERNIGHT LOWS. MANY SPOTS BY MONDAY NIGHT OUTSIDE OF THE NATURE COAST WILL STRUGGLE TO FALL BELOW 60 BY SUNRISE. NORMALLY COLDER NATURE COAST LOCATIONS SHOULD FALL NO LOWER THAN THE MID 50S. TUESDAY/TUESDAY NIGHT... A WARM APRIL DAY SEEMS ON TAP UNDER A MIX OF SUN AND CLOUDS. LOW LEVEL COLUMN CONTINUES TO MODIFY UNDER STACKED RIDGING. AFTERNOON HIGH TEMPERATURES AWAY FROM THE BEACHES SHOULD RISE WELL INTO THE 80S FOR MOST LOCATIONS...AND WOULD NOT BE SURPRISED TO SEE A FEW 90 DEGREE READINGS BY LATE IN THE DAY. A SLIGHTLY BETTER MOISTURE PROFILE OVER THE SOUTHERN THIRD OF THE FORECAST AREA MAY BE JUST ENOUGH TO SUPPORT AN ISOLATED AFTERNOON SHOWER OR 2 ALONG THE SEA-BREEZE. HOWEVER...USUALLY THIS TIME OF YEAR...YOU NEED SOME SYNOPTIC HELP TO GET ANY SEA-BREEZE INDUCED CONVECTION TO FIRE. THE UPPER RIDGE OVERHEAD WILL CERTAINLY NOT PROVIDE THIS SUPPORT...AND FOR NOW WILL KEEP POPS AT SILENT 10% DOWN TOWARD CHARLOTTE AND LEE COUNTIES. TUESDAY NIGHT LOOKS WARM WITH OVERNIGHT LOW TEMPS HOLDING AROUND 60S FAR NORTH AND IN THE LOWER/MIDDLE 60S SOUTH. ENJOY! && .LONG TERM (WEDNESDAY-SUNDAY)... MEDIUM RANGE GUIDANCE IS IN SLIGHTLY BETTER AGREEMENT COMPARED TO PREVIOUS MODEL CYCLES...HOWEVER SOLUTIONS CONTINUE TO DIVERGE LATE NEXT WEEK AND INTO THE UPCOMING WEEKEND WITH RESPECT TO THE PROGRESSIVENESS OF A COLD FRONT THROUGH THE AREA. WILL CONTINUE TO TAKE A BLENDED FORECAST APPROACH FOR NOW UNTIL THE MODEL SOLUTIONS COME INTO BETTER AGREEMENT. AS A RESULT...WILL NEED TO KEEP SLIGHT CHANCE OR LOW CHANCE POPS IN THE FORECAST EACH DAY THROUGH THE LONG TERM PERIOD...FOR PRIMARILY AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS. TEMPERATURES ARE EXPECTED TO RUN ABOVE NORMAL THROUGH FRIDAY BEFORE SETTLING BACK CLOSER TO SEASONAL LEVELS OVER THE UPCOMING WEEKEND. && .AVIATION... VFR CONDITIONS WITH FEW-SCT CU/SC AND SOME CIRRUS. GENERALLY EASTERLY WINDS WITH A LATE SEA BREEZE CLOSE TO THE COAST. && .MARINE... THE EASTERN GULF OF MEXICO WILL REMAIN ON THE SOUTHERN SIDE OF A RIDGE AXIS EXTENDING OFF THE GA/SC COAST THROUGH THE NEXT SEVERAL DAYS. RESULTING GRADIENT WILL PROVIDE A GENERAL EASTERLY FLOW TO THE REGION...HOWEVER MARINERS SHOULD ANTICIPATE WINDS BECOMING LOCALLY ONSHORE THE NEXT COUPLE OF AFTERNOON NEAR THE COAST WITH THE DEVELOPMENT OF THE SEA-BREEZE. THE NEXT FRONT WILL NOT APPROACH THE REGION UNTIL THE LATTER PORTION OF THE WEEK WITH SOUTHEAST AND SOUTH WINDS INCREASING AHEAD OF THIS SYSTEM. && .FIRE WEATHER... RISING TEMPERATURES THE NEXT SEVERAL DAYS WILL ALSO BE ACCOMPANIED BY A SLOW INCREASE IN LOW LEVEL MOISTURE. RELATIVE HUMIDITY VALUES WILL BOTTOM OUT IN THE UPPER 30S TO AROUND 40 PERCENT THE NEXT SEVERAL DAYS DURING THE AFTERNOON...AND NO RED FLAG CONDITIONS ARE ANTICIPATED. PATCHY FOG WILL BE INTRODUCED TO THE FORECAST FOR LATE MONDAY NIGHT AND EARLY TUESDAY MORNING. && .PRELIMINARY POINT TEMPS/POPS... TPA 63 82 65 85 / 0 0 0 10 FMY 63 86 65 85 / 0 0 0 10 GIF 59 86 61 87 / 0 0 0 10 SRQ 62 79 62 83 / 0 0 0 10 BKV 54 85 57 86 / 0 0 0 0 SPG 64 82 66 82 / 0 0 0 10 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA AVIATION...RUDE LONG TERM...JELSEMA
AREA FORECAST DISCUSSION
NWS MIAMI FL
219 PM EDT SUN APR 7 2013 .SHORT TERM (TONIGHT THROUGH TUESDAY NIGHT)... PLACED AN ISOLATED POP GRID FOR ALL ZONES THE REMAINDER OF THIS AFTERNOON. THE ONSHORE FLOW OF A FEW SHOWERS ALONG THE EAST COAST HAS BEEN PERSISTENT AND THE HRRR DOES INDICATE A CONTINUATION OF ISOLATED ACTIVITY DEVELOPING ACROSS THE INTERIOR AND COASTAL COLLIER COUNTY UNTIL VERY EARLY THIS EVENING. GLOBAL MODELS IN VERY GOOD AGREEMENT OVER THE NEXT 48-60 HOURS WITH MID LEVEL ZONAL FLOW THROUGH EARLY TUESDAY AND SURFACE HIGH PRESSURE ACROSS THE ATLANTIC AND NORTH FLORIDA. THIS WILL MAINTAIN A MODEST EASTERLY LOW LEVEL WIND FLOW AND A MOSTLY DRY WEATHER REGIME WITH STRONG SUBSIDENCE CAP REMAINING INTACT. THERE IS A SMALL INCREASE IN PWAT VALUES THAT WILL BE ROTATING WESTWARD BENEATH THE LARGE SCALE LOW LEVEL RIDGE OVER THE ATLANTIC THAT THE MODELS SHOW ARRIVING ACROSS SOUTH FLORIDA BY LATE TUESDAY AND TUESDAY NIGHT. FORECAST SOUNDINGS ALSO INDICATE THE CAP WILL BEGIN TO ERODE BY THIS TIME AND THIS SHOULD ALLOW FOR A SLIGHT INCREASE IN SHOWER ACTIVITY MOVING FROM THE ATLANTIC ONTO THE SOUTHEAST COAST. FOR THIS REASON, WILL MAINTAIN A SLIGHT CHANCE POP ALONG THE EAST COAST TUESDAY NIGHT AND SILENT POP ELSEWHERE AS RAIN CHANCES OVER THE INTERIOR AND COASTAL COLLIER COUNTY WILL BE TOO SMALL TO MENTION IN THOSE LOCATIONS. IN ADDITION, THE SHORT RANGE ENSEMBLE (SREF) IS SHOWING A SUBSTANTIAL INCREASED CHANCE FOR FOG OVER THE INTERIOR AND SOUTHWEST COAST FOR MONDAY NIGHT AND TUESDAY NIGHT AS THE LOW LEVEL MOISTURE INCREASES SO WILL INTRODUCE PATCHY FOG FOR THOSE LOCATIONS AT THAT TIME. .LONG TERM (WEDNESDAY THROUGH SUNDAY)... LOOKING AHEAD TOWARDS THE MIDDLE AND END OF THE WEEK, THE FORECAST BECOMES INCREASINGLY UNCERTAIN AS THE GFS AND ECMWF CONTINUE TO DIVERGE ON THE EVOLUTION OF THE POWERFUL MID LEVEL TROUGH THAT WILL BE MOVING INTO THE CENTRAL PLAINS STATES MONDAY NIGHT AND TUESDAY THEN SHIFTING EAST THROUGH THE WEEK. THE GFS PHASES IT IN WITH A NORTHERN STREAM TROUGH BY LATE WEDNESDAY AND THURSDAY AS THE MAIN SYSTEM LIFTS EAST INTO THE ATLANTIC. THIS BRINGS A TRAILING COLD FRONT ACROSS SOUTH FLORIDA ON FRIDAY SLOWLY PUSHING THROUGH THE REGION AND OFF THE SOUTHEAST COAST LATE SATURDAY AND SUNDAY. THIS WOULD ALSO BRING AN INCREASED CHANCE FOR CONVECTION ON FRIDAY AND POSSIBLY LINGERING INTO SATURDAY AS SHOWN BY THE LATEST MEX GUIDANCE. HOWEVER, THE ECMWF IS ALSO HOLDING ONTO ITS SLOWER SOLUTION WITH THE CENTRAL PLAINS TROUGH PHASING WITH THE UPSTREAM SYSTEM BUT FARTHER TO THE NORTH. IT THEN SHOWS THE FRONT STALLING ACROSS CENTRAL FLORIDA SATURDAY AND SUNDAY SO THE HIGHEST POPS WOULD BE OVER NEXT WEEKEND. AT THIS TIME, IT IS A WAIT AND SEE APPROACH WITH LITTLE CHANGE TO THE CURRENT FORECAST. && .MARINE... WIND AND SEAS WILL REMAIN BELOW ADVISORY LEVELS THROUGH THE END OF THIS WEEK WITH A LIGHT TO MODERATE EAST TO SOUTHEAST WIND AND SEAS OF 5 FEET OR LESS. THE WIND WILL INCREASE AND BECOME MORE SOUTHERLY BY FRIDAY AS A COLD FRONT MOVES INTO NORTH FLORIDA AND THE HIGH PRESSURE SHIFTS FARTHER EAST INTO THE ATLANTIC. && .FIRE WEATHER... RELATIVE HUMIDITY WILL REMAIN WELL ABOVE CRITICAL THRESHOLDS THROUGH THE END OF THIS WEEK AS LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE. THIS WILL ALSO INCREASE THE LIKELIHOOD FOR SOME LATE NIGHT FOG FORMATION OVER THE INTERIOR AND SOUTHWEST COAST AS THE WEEK PROGRESSES. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 67 80 69 81 / - - 10 10 FORT LAUDERDALE 70 80 70 82 / - - 10 10 MIAMI 68 77 71 82 / - - 10 10 NAPLES 65 81 65 84 / - - - 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...30/KOB AVIATION/RADAR...23/SK
AREA FORECAST DISCUSSION
NWS TOPEKA KS
324 PM CDT SUN APR 7 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 255 PM CDT SUN APR 7 2013 19Z WATER VAPOR IMAGERY SHOWS A QUASI-ZONAL FLOW ACROSS THE PLAINS WITH A LOW AMPLITUDE SHORTWAVE MOVING ACROSS THE CO AND NM ROCKIES. AT THE SURFACE A TROUGH OF LOW PRESSURE IN THE LEE OF THE ROCKIES HAS STRENGTHENED AND CAUSED SOUTH AND SOUTHEAST WINDS TO INCREASE BRINGING BETTER MOISTURE NORTH INTO SOUTHERN AND EASTERN KS. THE UPPER WAVE IS EXPECTED TO MOVE ACROSS THE STATE THIS EVENING...AND TRIGGER ADDITIONAL THUNDERSTORM DEVELOPMENT ACROSS CENTRAL KS. THIS ACTIVITY SHOULD MOVE ACROSS NORTHEAST KS THROUGH THE EVENING. 18Z RUC SHOWS THE BETTER INSTABILITY CURRENTLY OVER SOUTHERN KS WHERE THE DEWPOINTS ARE IN THE UPPER 50S. AS THE SOUTHERLY WINDS CONTINUE TO BRING THE MOISTURE AND INSTABILITY INTO EAST CENTRAL KS...THERE IS THE POTENTIAL THAT ANY CONVECTION IN SOUTH CENTRAL KS COULD MOVE INTO THE AREA AND REMAIN ORGANIZED ENOUGH FOR A SEVERE THREAT. PERHAPS THE GREATER THREAT FOR SEVERE WEATHER MAY COME FROM ANY THUNDERSTORM DEVELOPMENT IN CENTRAL KS THAT MOVES IN FROM THE WEST THIS EVENING. MODELS SHOW LOW LEVEL SHEER INCREASING AS THE LOW LEVEL JET INCREASES. HOWEVER THE RAP CONTINUES TO SHOW THE BEST INSTABILITY REMAINING ACROSS CENTRAL AND SOUTHERN KS AND ALONG THE SOUTHWESTERN EDGE OF THE FORECAST AREA. THERE COULD BE A SHORT WINDOW FOR SEVERE WEATHER IF DISCRETE STORMS WERE ABLE TO FORM AND MOVE INTO THE AREA. GIVEN THE INCREASING 0-1KM SHEER PARAMETERS...A TORNADO CAN NOT BE RULED OUT EITHER. EVENTUALLY STORMS SHOULD BECOME MORE ELEVATED WITH CELL MERGERS DISRUPTING UPDRAFT ORGANIZATION. THINK THAT AS THE UPPER LEVEL WAVE PASSES EAST AROUND MIDNIGHT...PRECIP CHANCES WILL QUICKLY DIMINISH OVERNIGHT. OVERNIGHT LOWS SHOULD BE PRETTY MILD WITH CONTINUED SOUTH WINDS AND MOSTLY CLOUDY SKIES PREVENTING MUCH IN THE WAY OF RADIATIONAL COOLING. SOME OF THE OBJECTIVE GUIDANCE HAS LOW STRATUS MOVING IN WITH CONTINUED MOISTURE ADVECTION FROM THE SOUTH. THEREFORE KEPT AT LEAST MOSTLY CLOUDY SKIES IN THE FORECAST FOR TONIGHT. FOR MONDAY FORECAST SOUNDINGS SHOW AN ELEVATED MIXED LAYER MOVING OVER THE FORECAST AREA WITH LITTLE IN THE WAY OF LARGE SCALE FORCING OR SURFACE BASED LIFT. BECAUSE OF THIS HAVE REMOVED POPS FOR MUCH OF THE DAY THINKING THE BOUNDARY LAYER WILL REMAIN CAPPED. THE FORECAST DOES SHOW CHANCES BEGINNING TO INCREASE LATE IN THE DAY AS DAY TIME HEATING COULD CAUSE THE CAP TO WEAKEN ACROSS NORTH CENTRAL KS. DEPENDING ON WHETHER THE LOW CLOUDS DEVELOP OR NOT...HIGHS SHOULD MAKE IT INTO THE 70S. DID LOWER HIGHS A COUPLE DEGREES ACROSS EAST CENTRAL KS WHERE CLOUDS ARE EXPECTED TO PERSIST LONGER. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 255 PM CDT SUN APR 7 2013 BY THE EVENING HOURS ON MONDAY...A CONSIDERABLE EML MOVES OVER THE MAJORITY OF THE CWA. HAVE BACKED OFF ON POPS AS A RESULT ALONG AND SOUTH OF I70...AND MAY NEED TO BACK OFF EVEN MORE. TO THE NORTH...THE CAP IS MUCH WEAKER...AND WOULD ANTICIPATE THAT BY SUNRISE THERE WILL BE ENOUGH LIFT FROM THE LEADING WAVE AS WELL AS CONVERGENCE IN THE LLJ AND THE SURFACE TROF FOR A LINE OF THUNDERSTORMS ALONG THE KS NEBRASKA BORDER. COLD FRONT TO THE WEST IS CONCURRENTLY SURGING TO THE SOUTHEAST AND MAY IMPINGE ON THE FAR NW CORNER OF THE CWA BY AROUND 12Z TUESDAY...AND WILL CARRY HIGHEST POPS TO THE NW. CONDITIONS BY 12Z TUESDAY WILL BE IMPACTED BY PREVIOUS NIGHTS WEATHER...BUT STILL APPEARS THAT LATE MORNING INTO THE EVENING HOURS WILL BE THE GREATEST RISK FOR OUR FORECAST AREA FOR STRONG TO SEVERE STORMS. THE DRYLINE AND FRONT COME TOGETHER OUT IN WESTERN KANSAS IN THE MORNING AND BOTH MERGE AND MOVE INTO THE WESTERN COUNTIES BY EARLY AFTERNOON. EC AND GFS SLIGHTLY SLOWER AND COULD ALLOW FOR A BIT MORE BUILDUP OF INSTABILITY ACROSS THE EAST BEFORE THE FRONT SURGES THROUGH LATE DAY. WITH WINDS THROUGH THE COLUMN NEARLY RUNNING PARALLEL TO THE FRONT...DISCRETE CELLS THAT INITIALLY FORM MAY EVOLVE QUICKLY INTO A LINE THAT ADVANCES ACROSS THE CWA THROUGH THE EVENING HOURS. THIS WOULD MAKE SEVERE WINDS THE PRIMARY CONCERN...ALTHOUGH WITH A QUICK INCREASE IN WIND SPEEDS IN THE LOW LEVELS AND GOOD LOW LEVEL HELICITY CANT RULE OUT ISOLATED TORNADOES...ESP IN EARLY ONSET OF THE CONVECTION AND IN ANY STORMS THAT CAN FORM OUT IN THE WARM SECTOR. TUESDAY NIGHT THROUGH FRIDAY BRING AN UNSEASONABLY COOL PERIOD AS THE UPPER LOW CONTINUES TO DRAW COLDER AIR INTO THE PLAINS THROUGH THE END OF THE WEEK. DAYTIME HIGHS WED WILL STRUGGLE TO REACH 40S WHILE THURS AND FRI MAKE A SLOW CLIMB INTO THE MIDDLE 50S. BY THE WEEKEND SOUTHERLY FLOW AT THE SURFACE AND WESTERLY FLOW ALOFT BRING TEMPERATURES BACK TOWARD NORMAL WITH SOME CHANCES FOR RAIN WITH SOME WEAK WAVES IN THE FLOW. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1234 PM CDT SUN APR 7 2013 TIMING OF CONVECTION DOSE NOT APPEAR TO BE MUCH DIFFERENT FROM THE PREV FORECAST WITH THE UPPER DISTURBANCE EXPECTED TO MOVE ACROSS THE AREA THROUGH THE EVENING. BIGGEST UNCERTAINTY IS WITH CIGS OVERNIGHT. BOTH THE MET AND MAV OBJECTIVE GUIDANCE IS BRINGING LIFT CIGS IN WITH CONTINUED LOW LEVEL MOISTURE ADVECTION. CONFIDENCE IS MARGINAL...SO LEFT THE FORECAST FOR MVFR CIGS AFTER THE PRECIP. LATER SHIFTS CAN REEVALUATE THE LIFR CIGS POTENTIAL. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...WOLTERS LONG TERM...CRAVEN AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1234 PM CDT SUN APR 7 2013 .SHORT TERM...(TODAY) ISSUED AT 442 AM CDT SUN APR 7 2013 TODAY...DEEPER MOISTURE EXTENDING FROM SOUTHERN OK AND EAST TX WILL BE ADVECTED NORTHWARD AS A LEE SURFACE TROUGH DEEPENS ACROSS THE CENTRAL AND WESTERN HIGH PLAINS. THE SOUTHERLY LOW- LEVEL FLOW WILL ADVECT THIS DEEPER MOISTURE NORTHWARD ACROSS EASTERN KS LATE THIS AFTERNOON. THE WESTERN GULF OF MEXICO IS NOT AT EQUILIBRIUM EARLY THIS MORNING...BUT THE RESIDUAL MOISTURE RETURN SHOULD BE SUFFICIENT TO ALLOW MID TO UPPER 50 DEWPOINTS TO ADVECT NORTHWARD ACROSS THE CWA BY LATE AFTERNOON. MEANWHILE...A SHORTWAVE LENGTH H5 TROUGH WAS MOVING EASTWARD ACROSS CENTRAL CO...SOUTHWARD INTO NORTHWEST NM. THE NAM...ECMWF AND GFS SHOW THIS H5 TROUGH MOVING EAST ACROSS WESTERN AND CENTRAL KS TODAY. STRONGER ASCENT AHEAD OF THIS H5 TROUGH AND THE STRONGER ISENTROPIC LIFT ON THE NORTH SIDE OF DEEPER MOISTURE RETURN WILL ALLOW SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS TO DEVELOP FROM SOUTH TO NORTH ACROSS THE CWA DURING THE MID AND LATE AFTERNOON HOURS. THE VERTICAL WIND SHEAR LOOKS TO BE STRONG WITH 0-6KM SHEAR OF 40 TO 60 KTS ACROSS THE CWA THROUGH THE LATE AFTERNOON HOURS. INSTABILITY WILL INCREASE THROUGH THE AFTERNOON AS THE DEEPER MOISTURE ADVECTS NORTHWARD TO AT LEAST I-70. GIVEN STEEP LAPSE RATES FROM 700MB TO THE SURFACE...ONCE THE DEEPER MOISTURE ADVECT FAR ENOUGH NORTH WE SHOULD SEE SBCAPE INCREASE TO 1,000 TO 1,500 J/KG FROM I-70 SOUTH. THE NAM MODEL EVEN SHOWS AN ENHANCED BAND OF 0-1KM SRH OF 80-100 J/KG ALONG THE I-35 CORRIDOR BY 21Z AND LIFTING NORTHWARD TO I-70 BY 00Z. THIS WOULD BE SUFFICIENT FOR DISCRETE SUPERCELL TO POTENTIALLY PRODUCE ISOLATED TORNADOES. HOWEVER...THE MODE OF CONVECTION IS STILL IN QUESTION. THE ECMWF...GFS...AND NAM ALL SHOW NUMEROUS THUNDERSTORMS DEVELOPING ALONG I-35 AFTER 21Z AND EXTENDING WESTWARD TOWARDS ICT. IF A COMPLEX OR CLUSTER OF THUNDERSTORMS DEVELOPS LATE IN THE AFTERNOON HOURS ALONG THE NORTHERN EDGE OF DEEPER MOISTURE RETURN...THEN THE PRIMARY THREAT WILL LARGE HAIL AND SEVERE WIND GUSTS. THIS COMPLEX OF STORMS WILL DEVELOP NORTHWARD ACROSS EAST CENTRAL KS LATE IN THE AFTERNOON. IF THE THUNDERSTORMS REMAIN DISCRETE...THEN GIVEN THE 0-1KM SRH AND INSTABILITY...THEN ISOLATED TORNADOES COULD NOT BE RULED OUT FOR PORTIONS OF THE CWA...SOUTH OF I-70. THE RAP AND (ARW) WRF...TWO OF OUR MESOSCALE MODELS...SHOW THE INITIATION OF DEEP MOIST CONVECTION WEST AND SOUTHWEST OF THE CWA THROUGH THE LATE AFTERNOON HOURS. THE INITIAL MODE LOOKS DISCRETE WITH STORM MERGERS OCCURRING AS THEY MOVE NORTHEAST ACROSS THE CWA DURING THE EARLY EVENING HOURS. STAY TUNED TO LATER UPDATES ON THE POTENTIAL FOR SEVERE WEATHER LATE THIS AFTERNOON AND EVENING. TEMPERATURES WILL WARM INTO THE LOWER TO MID 70S WITH PATCHES OF DENSE HIGH CLOUD COVER SPREADING ACROSS THE CWA THIS MORNING. CU SHOULD BEGIN TO DEVELOP AS THE DEEPER MOISTURE SURGES NORTHWARD THIS AFTERNOON. GARGAN .LONG TERM...(TONIGHT THROUGH SATURDAY) ISSUED AT 442 AM CDT SUN APR 7 2013 CONVECTIVE COMPLEX OF SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP/EXPAND EAST AND NORTHEAST ACROSS PRIMARILY THE SOUTHEAST HALF OF THE CWA THROUGH THE EARLY AND MID EVENING HOURS WITH A THREAT FOR PRIMARILY LARGE HAIL WITH THE STRONGER STORMS. HOWEVER...AS THE SHORTWAVE TROUGH MOVES THROUGH BY LATE EVENING...THE LLVL FLOW WILL BEGIN TO VEER AND ALLOW FOR SOME DRIER AIR TO ADVECT EASTWARD WHICH WILL FAVOR THE MORE EASTWARD PROGRESSION OF THE POSSIBLE MCS. HAVE THEREFORE TRENDED THE HIGHER POPS THROUGH THE EARLY/MID EVENING...THEN A GRADUAL DECREASED POP THROUGH LATE EVENING/MIDNIGHT...THEN A MUCH MORE RAPID DROP IN POPS AFTER MIDNIGHT WEST TO EAST ACROSS THE CWA. WILL KEEP THE SOUTHEAST CWA WARMER WITH THE CLOUDS AND HIGHER DEWPOINTS IN THE UPPER 50S WITH NEAR 50 IN THE FAR NORTH CENTRAL. ON MONDAY...OVERALL LACK OF LARGE SCALE ASCENT/FORCING WITHIN AN ENVIRONMENT EXHIBITING A RAPIDLY STRENGTHENING ELEVATED MIXED LAYER (EML) DOES NOT INCREASE CONFIDENCE IN CARRYING POPS BEYOND LOW END CHANCE CATEGORY. HAVE REMOVED POPS FOR MOST OF THE MORNING...BUT CARRIED LOW POPS IN THE LATE MORNING/AFTERNOON...ALTHOUGH IMPRESSIVE INHIBITION MAY WARRANT LOWERING/OR REMOVING POPS MORE. KEPT HIGHS IN THE LOW TO MID 70S DUE TO EXPECTED STRATUS DECK BENEATH INVERSION. BY MONDAY NIGHT...MORE CONVECTION IS EXPECTED TO ADVANCE/DEVELOP EASTWARD FROM WESTERN/CENTRAL KANSAS THROUGH THE NIGHT PRIMARILY ALONG THE NORTH OF THE WARM FRONT AS LLVL JET INCREASES THROUGH THE NIGHT. THE FOCUS FOR THIS HAS CONTINUES TO TREND NORTHWARD WITH TIME AND STRONG CAPPING OVER THE CWA MAY ALSO INHIBIT THE SOUTH AND EASTWARD EXTENT OF THE CONVECTION AS WELL. FOR NOW...HAVE KEPT LIKELY POPS ACROSS THE NORTHERN 2/3 OF THE CWA...BUT IF MODEL TRENDS CONTINUE...THE HIGHER POPS MAY NEED TO BE TRIMMED/SHIFTED MORE NORTHWARD CLOSER TO THE NE BORDER. TUESDAY AND TUESDAY NIGHT STILL APPEARS TO BE THE MOST ACTIVE TIME FRAME FOR THIS STORM SYSTEM ACROSS OUR CWA AS A DEEPENING SFC LOW/COLD FRONT ADVANCES EASTWARD ACROSS THE AREA AS THE MAIN SHORTWAVE ROTATES NORTHEAST OUT OF THE LONGER WAVE TROUGH IN THE WEST INTO THE NORTHERN PLAINS EARLY WEDNESDAY. CONVECTION COULD FIRST INITIATE OVER CENTRAL KS THEN CONGEAL INTO A POSSIBLE SQUALL LINE AS IT MOVES EAST THROUGH THE AFTERNOON/EVENING WITH ALL MODES OF SEVERE WEATHER POSSIBLE DURING THIS TIME FRAME BEFORE THE FRONT USHERS IN COOLER AND DRIER AIR INTO EASTERN KS LATE IN THE NIGHT. WILL KEEP A LINGERING CHANCE FOR DECREASING CONVECTION/RAIN POTENTIAL ON WEDNESDAY WITH SHOWERS EXITING THE CWA WEDNESDAY NIGHT...THEN DRY THURSDAY INTO FRIDAY NIGHT. A SLIGHT CHANCE FOR SHOWERS WILL RETURN BY SATURDAY. AFTER HIGHS IN THE 60S/70S ON TUESDAY...WEDNESDAY TEMPS WILL COOL INTO THE 40S AND 50S FOR WEDNESDAY AND THURSDAY...THEN THE 50S FRIDAY AND THE 60S FOR SATURDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1234 PM CDT SUN APR 7 2013 TIMING OF CONVECTION DOSE NOT APPEAR TO BE MUCH DIFFERENT FROM THE PREV FORECAST WITH THE UPPER DISTURBANCE EXPECTED TO MOVE ACROSS THE AREA THROUGH THE EVENING. BIGGEST UNCERTAINTY IS WITH CIGS OVERNIGHT. BOTH THE MET AND MAV OBJECTIVE GUIDANCE IS BRINGING LIFT CIGS IN WITH CONTINUED LOW LEVEL MOISTURE ADVECTION. CONFIDENCE IS MARGINAL...SO LEFT THE FORECAST FOR MVFR CIGS AFTER THE PRECIP. LATER SHIFTS CAN REEVALUATE THE LIFR CIGS POTENTIAL. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...GARGAN LONG TERM...63 AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS JACKSON KY
136 PM EDT SUN APR 7 2013 .UPDATE... ISSUED AT 1256 PM EDT SUN APR 7 2013 UPDATED NDFD AND ZFP FOR LATEST OBSERVATIONAL TRENDS. HAVE DECREASED RAIN CHANCES IN THE FAR NORTH AND INCREASED CLOUD COVER ACROSS THE ENTIRE AREA. MINIMUM RELATIVE HUMIDITIES IN THE SOUTHEAST PART OF FORECAST AREA HAVE REACHED 30 TO 35 PERCENT...BUT SHOULD NOT GO TOO MUCH LOWER...WITH MINIMUMS 25 TO 30 PERCENT EXPECTED THIS AFTERNOON. UPDATE ISSUED AT 1027 AM EDT SUN APR 7 2013 TEMPERATURE RISE THIS MORNING HAS BEEN QUICKER THAN FORECAST...BUT AT THE SAME TIME CLOUDS ARE ALSO INCREASING QUICKER. HAVE ADJUSTED THE HOURLY TEMPERATURE FORECAST AND SKY COVER FORECAST TO ACCOUNT FOR THIS. INCREASING CLOUDS SHOULD KEEP CURRENT MAXIMUM TEMPERATURE FORECAST ON TARGET. ANOTHER ITEM TO ADDRESS FOR THIS UPDATE ARE DEWPOINTS AND POTENTIAL FIRE WEATHER CONCERNS. DEWPOINTS HAVE BEEN RESPONDING TO INCREASING SOUTHWEST FLOW...AND DESPITE RELATIVE HUMIDITY CURRENTLY IN THE 30 TO 40 PERCENT RANGE...WE SHOULD SEE RELATIVE HUMIDITY STAY ABOVE CRITICAL THRESHOLDS. THIS WILL BE MONITORED CLOSELY THOUGH AS WINDS ARE MUCH STRONGER THAN YESTERDAY. PLAN TO ISSUE AN SPS FOR ENHANCED WILD FIRE THREAT. FINALLY HAVE MADE SOME ADJUSTMENTS TO SHOWER CHANCES THIS AFTERNOON. LATEST HRRR POINTS TOWARDS DELAYING THE ONSET OF RAIN CHANCES AND ALSO EXTENDING THE CHANCE FURTHER SOUTH. HOWEVER THEN HRRR IS OVERPLAYING PRECIPITATION CHANCES THIS MORNING. HAVE FOLLOWED THE IDEA OF DELAYING PRECIPITATION CHANCES...BUT DID NOT EXTEND THE CHANCE FURTHER SOUTH. HAVE ACTUALLY LOWERED THE PROBABILITY FROM LIKELY TO CHANCE IN THE NORTH AS WELL. NDFD AND ZFP HAVE BEEN UPDATED. UPDATE ISSUED AT 658 AM EDT SUN APR 7 2013 FRONTAL BOUNDARY IS JUST ABOUT TO THE CINCINNATI METRO AREA WITH THE LINE OF SHOWERS PRETTY MUCH NON-EXISTENT AT THE TIME. HRRR IS ALSO DOWNPLAYING ACTIVITY ALONG THIS BOUNDARY THROUGH THE MORNING HOURS WHICH SEEMS VERY REASONABLE. STILL LOOKS LIKE WE COULD SEE AN UPTICK IN SHOWER OR THUNDERSTORM ACTIVITY THIS AFTERNOON AS INSTABILITY INCREASES JUST AHEAD OF THE STALLING BOUNDARY. MOST OF THE ACTIVITY MAY BE TIED TO WHETHER OR NOT WE CAN GET ENOUGH INSTABILITY. GIVEN DEWPOINTS MUCH LOWER THAN PREVIOUSLY ANTICIPATED...THIS COULD BE IN JEOPARDY. HOWEVER...WILL MAINTAIN THE CURRENT POPS AND LET DAYSHIFT RE-EVALUATE IF WE WILL SEE ANY SHOWER ACTIVITY IN THE FAR NORTH TODAY. DEWPOINTS ARE FINALLY STARTING TO CREEP UP A BIT...BUT REMAIN MUCH SLOWER THAN MODEL GUIDANCE. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 255 AM EDT SUN APR 7 2013 FAIRLY QUIET WEATHER EARLY THIS SUNDAY MORNING. A VIGOROUS SHORTWAVE IS PUSHING EAST ACROSS MICHIGAN THIS MORNING WITH A WEAK SURFACE BOUNDARY BEING DRAGGED ACROSS THE OHIO RIVER VALLEY. AT THE MOMENT...NOT MUCH ACTIVITY OUTSIDE OF A NARROW LINE OF BROKEN SHOWERS PUSHING EAST ACROSS NORTHERN INDIANA...BACK INTO SOUTHERN ILLINOIS. HRRR SEEMS TO HAVE A DECENT HANDLE ON THE RADAR TRENDS THIS MORNING. THE SHORTWAVE WILL EXIT TO THE EAST TODAY...WITH THE FRONTAL BOUNDARY STALLING ACROSS NORTHERN WEST VIRGINIA AND NORTHERN KENTUCKY. MODELS SEEM TO BE IN VERY GOOD AGREEMENT ON THIS PLACEMENT. THE BEST CHANCES FOR ANY RAIN WITH THIS FRONT WILL RESIDE ALONG THIS BOUNDARY...AND WILL LIKELY REMAIN ALONG AND NORTH OF I-64. MEANWHILE...DRY CONDITIONS WILL LIKELY PERSIST ACROSS THE REST OF EASTERN KENTUCKY. WITH MOISTURE RECOVERY VERY POOR AT BEST OVERNIGHT AND THE PROSPECTS OF DECENT MIXING TODAY...HAVE GONE WELL BELOW GUIDANCE WITH DEWPOINTS YET AGAIN TODAY. IN FACT...A FEW PLACES...ESPECIALLY IN SOUTHEAST KENTUCKY COULD SEE AFTERNOON RELATIVE HUMIDITIES FALL TO UNDER 30 PERCENT. WITH STRONGER SOUTHWEST WINDS TODAY...AHEAD OF THE FRONTAL BOUNDARY...THIS COULD CREATE A PERIOD OF DANGEROUS FIRE WEATHER CONDITIONS. THIS THREAT WILL HIGHLIGHTED IN THE HWO AND FIRE WEATHER PLANNING FORECAST. HIGHS TODAY WILL CLIMB EVEN HIGHER INTO THE LOW TO MID 70S...EXCEPT IN THE NORTH...WHERE CLOUDS AND PERHAPS PRECIPITATION MAY KEEP LOCATIONS IN THE 60S. FRONTAL BOUNDARY WILL SLOWLY DRIFT BACK TO THE NORTH THIS EVENING...WITH RAIN CHANCES DECREASING FROM SOUTH TO NORTH. SKIES SHOULD REMAIN MOSTLY TO PARTLY CLEAR OVERNIGHT...ALLOWING SOME VALLEY LOCATIONS TO DECOUPLE AND FALL BACK INTO THE 40S...WHILE RIDGES STAY IN THE 50S. ANOTHER VIGOROUS SHORTWAVE WILL TRACK NORTHEAST THROUGH THE PLAINS ON MONDAY...FURTHER PUSHING THE BOUNDARY TO THE NORTH AND KEEPING EASTERN KENTUCKY DOMINATED BY STRONG RIDGING. A VERY WARM DAY IS ON TAP WITH HIGHS SURGING WELL INTO THE 70S AREAWIDE. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 255 AM EDT SUN APR 7 2013 MODELS CONTINUE TO SHOW GENERAL AGREEMENT EARLY IN THE PERIOD IN TERMS OF HOW SYSTEMS WILL AFFECT OUR LOCAL WEATHER. PATTERN AMPLIFICATION WILL BE ONGOING...WITH A WESTERN CONUS UPPER TROUGH AND AND A SOUTHEAST CONUS UPPER RIDGE. STRONG SURFACE LOW PRESSURE WILL TRACK FROM CO AT THE START OF THE PERIOD TO THE VICINITY OF IL/IN BY THURSDAY MORNING. A FRONTAL BOUNDARY EXTENDING EAST FROM THE LOW WILL BE LAID OUT NORTH OF THE OHIO RIVER. MODELS DISAGREE ON EXACTLY HOW FAR NORTH/SOUTH IT WILL BE POSITIONED. THE ECMWF MANAGES TO BRING IT FURTHER SOUTH THAN ANY OTHER MODEL...MAKING IT INTO THE NORTHERN PART OF THE JKL FORECAST AREA BY 12Z THURSDAY. WITH ALL OTHER GUIDANCE SHOWING IT FURTHER NORTH...WILL GO WITH A FORECAST THAT KEEPS OUR AREA IN THE WARM SECTOR. A BROAD ZONE OF WARM AIR ADVECTION WILL BRING MOISTURE NORTH FROM THE GULF OF MEXICO AND LIFT IT ACROSS THE FRONT. THE BEST CHANCE OF RAIN WITH THIS WILL BE WELL TO OUR NORTH...BUT CAN NOT RULE OUT SOME SHOWERS MAKING IT INTO THE NORTHERN PART OF THE AREA. THE FORECAST BECOMES MORE PROBLEMATIC LATER IN THE WEEK DUE TO CONTINUED DIFFERENCES IN MODEL TIMING OF THE SURFACE LOW AND ITS TRAILING COLD FRONT. THE ECMWF IS THE SLOWEST...WITH LOCAL FROPA NOT HAPPENING UNTIL FRIDAY AFTERNOON. THE END OF THE NAM RUN ON WED MORNING LOOKS SIMILAR TO THE GFS...WHICH ENDS UP WITH FROPA DURING THE DAY THURSDAY. THERE ARE SOME MEMBERS OF THE GFS ENSEMBLE WHICH SHOW SIMILAR TIMING AS THE ECMWF...BUT THE GFS ENSEMBLE MEAN IS MORE SUPPORTIVE OF THE OPERATIONAL GFS. WILL FAVOR A COMPROMISE SOLUTION CLOSER TO THE GFS. WITH THAT SAID...HIGHEST POPS...IN LIKELY CATEGORY...WILL BE ON THURSDAY AND THURSDAY NIGHT. WILL USE HIGH CHANCE ON FRIDAY TO LEND SOME CREDENCE TO THE ECMWF. ALL MODELS SHOW INSTABILITY AHEAD OF THE COLD FRONT...AND A CHANCE OF THUNDER WILL BE USED WITH THE APPROACH AND PASSAGE OF THE COLD FRONT. WINDS ALOFT LOOK TO BE QUITE STRONG...AND WOULD SUPPORT SEVERE WX. HOWEVER...THE DEGREE OF INSTABILITY DOES NOT REALLY STAND OUT. THE SET-UP WILL NEED TO CONTINUE TO BE WATCHED. THE WARMEST AIR MASS OF THE SEASON SO FAR WILL BE IN PLACE UP UNTIL COLD FROPA. NEEDLESS TO SAY...FRONTAL TIMING WILL PLAY A KEY ROLE IN TEMPS LATE IN THE PERIOD...AND LEADS TO A LOWER CONFIDENCE IN THE TEMPERATURE FORECAST FOR THURSDAY INTO FRIDAY...AND A POTENTIAL FOR MORE SIZEABLE ERRORS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 136 PM EDT SUN APR 7 2013 A COLD FRONT CONTINUES TO SLOWLY SAG SOUTH ACROSS OH AND INDIANA. CLOUDS HAVE INCREASED AHEAD OF THE FRONT ACROSS KY...BUT CEILINGS ARE EXPECTED TO REAMIN VFR THROUGH MONDAY. ISOLATED THUNDERSTORMS ARE STILL POSSIBLE ACROSS FAR NORTHERN KY THIS AFTERNOON...BUT IF ANY OCCUR THEY WILL BE WELL NORTH OF THE TAF SITES. GUSTY SOUTHWEST WINDS THIS AFTERNOON WILL DIMINISH THIS EVENING. && .FIRE WEATHER... ISSUED AT 1051 AM EDT SUN APR 7 2013 DEWPOINTS HAVE BEEN RISING IN THE INCREASING SOUTHWEST FLOW...AND DESPITE RELATIVE HUMIDITY CURRENTLY IN THE 30 TO 40 PERCENT RANGE OVER SOUTHEAST KY...WE SHOULD SEE RELATIVE HUMIDITY STAY ABOVE CRITICAL THRESHOLDS. HOWEVER SOME SPOTS WILL BE NEAR 25 PERCENT RH THIS AFTERNOON. THIS WILL BE MONITORED CLOSELY AS WINDS ARE MUCH STRONGER THAN YESTERDAY...WITH GUSTS TO 30 MPH EXPECTED FOR THIS AFTERNOON. HAVE ISSUED AN SPS FOR ENHANCED WILD FIRE THREAT. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SBH SHORT TERM...KAS LONG TERM...HAL AVIATION...SBH FIRE WEATHER...SBH
AREA FORECAST DISCUSSION
NWS JACKSON KY
1257 PM EDT SUN APR 7 2013 .UPDATE... ISSUED AT 1256 PM EDT SUN APR 7 2013 UPDATED NDFD AND ZFP FOR LATEST OBSERVATIONAL TRENDS. HAVE DECREASED RAIN CHANCES IN THE FAR NORTH AND INCREASED CLOUD COVER ACROSS THE ENTIRE AREA. MINIMUM RELATIVE HUMIDITIES IN THE SOUTHEAST PART OF FORECAST AREA HAVE REACHED 30 TO 35 PERCENT...BUT SHOULD NOT GO TOO MUCH LOWER...WITH MINIMUMS 25 TO 30 PERCENT EXPECTED THIS AFTERNOON. UPDATE ISSUED AT 1027 AM EDT SUN APR 7 2013 TEMPERATURE RISE THIS MORNING HAS BEEN QUICKER THAN FORECAST...BUT AT THE SAME TIME CLOUDS ARE ALSO INCREASING QUICKER. HAVE ADJUSTED THE HOURLY TEMPERATURE FORECAST AND SKY COVER FORECAST TO ACCOUNT FOR THIS. INCREASING CLOUDS SHOULD KEEP CURRENT MAXIMUM TEMPERATURE FORECAST ON TARGET. ANOTHER ITEM TO ADDRESS FOR THIS UPDATE ARE DEWPOINTS AND POTENTIAL FIRE WEATHER CONCERNS. DEWPOINTS HAVE BEEN RESPONDING TO INCREASING SOUTHWEST FLOW...AND DESPITE RELATIVE HUMIDITY CURRENTLY IN THE 30 TO 40 PERCENT RANGE...WE SHOULD SEE RELATIVE HUMIDITY STAY ABOVE CRITICAL THRESHOLDS. THIS WILL BE MONITORED CLOSELY THOUGH AS WINDS ARE MUCH STRONGER THAN YESTERDAY. PLAN TO ISSUE AN SPS FOR ENHANCED WILD FIRE THREAT. FINALLY HAVE MADE SOME ADJUSTMENTS TO SHOWER CHANCES THIS AFTERNOON. LATEST HRRR POINTS TOWARDS DELAYING THE ONSET OF RAIN CHANCES AND ALSO EXTENDING THE CHANCE FURTHER SOUTH. HOWEVER THEN HRRR IS OVERPLAYING PRECIPITATION CHANCES THIS MORNING. HAVE FOLLOWED THE IDEA OF DELAYING PRECIPITATION CHANCES...BUT DID NOT EXTEND THE CHANCE FURTHER SOUTH. HAVE ACTUALLY LOWERED THE PROBABILITY FROM LIKELY TO CHANCE IN THE NORTH AS WELL. NDFD AND ZFP HAVE BEEN UPDATED. UPDATE ISSUED AT 658 AM EDT SUN APR 7 2013 FRONTAL BOUNDARY IS JUST ABOUT TO THE CINCINNATI METRO AREA WITH THE LINE OF SHOWERS PRETTY MUCH NON-EXISTENT AT THE TIME. HRRR IS ALSO DOWNPLAYING ACTIVITY ALONG THIS BOUNDARY THROUGH THE MORNING HOURS WHICH SEEMS VERY REASONABLE. STILL LOOKS LIKE WE COULD SEE AN UPTICK IN SHOWER OR THUNDERSTORM ACTIVITY THIS AFTERNOON AS INSTABILITY INCREASES JUST AHEAD OF THE STALLING BOUNDARY. MOST OF THE ACTIVITY MAY BE TIED TO WHETHER OR NOT WE CAN GET ENOUGH INSTABILITY. GIVEN DEWPOINTS MUCH LOWER THAN PREVIOUSLY ANTICIPATED...THIS COULD BE IN JEOPARDY. HOWEVER...WILL MAINTAIN THE CURRENT POPS AND LET DAYSHIFT RE-EVALUATE IF WE WILL SEE ANY SHOWER ACTIVITY IN THE FAR NORTH TODAY. DEWPOINTS ARE FINALLY STARTING TO CREEP UP A BIT...BUT REMAIN MUCH SLOWER THAN MODEL GUIDANCE. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 255 AM EDT SUN APR 7 2013 FAIRLY QUIET WEATHER EARLY THIS SUNDAY MORNING. A VIGOROUS SHORTWAVE IS PUSHING EAST ACROSS MICHIGAN THIS MORNING WITH A WEAK SURFACE BOUNDARY BEING DRAGGED ACROSS THE OHIO RIVER VALLEY. AT THE MOMENT...NOT MUCH ACTIVITY OUTSIDE OF A NARROW LINE OF BROKEN SHOWERS PUSHING EAST ACROSS NORTHERN INDIANA...BACK INTO SOUTHERN ILLINOIS. HRRR SEEMS TO HAVE A DECENT HANDLE ON THE RADAR TRENDS THIS MORNING. THE SHORTWAVE WILL EXIT TO THE EAST TODAY...WITH THE FRONTAL BOUNDARY STALLING ACROSS NORTHERN WEST VIRGINIA AND NORTHERN KENTUCKY. MODELS SEEM TO BE IN VERY GOOD AGREEMENT ON THIS PLACEMENT. THE BEST CHANCES FOR ANY RAIN WITH THIS FRONT WILL RESIDE ALONG THIS BOUNDARY...AND WILL LIKELY REMAIN ALONG AND NORTH OF I-64. MEANWHILE...DRY CONDITIONS WILL LIKELY PERSIST ACROSS THE REST OF EASTERN KENTUCKY. WITH MOISTURE RECOVERY VERY POOR AT BEST OVERNIGHT AND THE PROSPECTS OF DECENT MIXING TODAY...HAVE GONE WELL BELOW GUIDANCE WITH DEWPOINTS YET AGAIN TODAY. IN FACT...A FEW PLACES...ESPECIALLY IN SOUTHEAST KENTUCKY COULD SEE AFTERNOON RELATIVE HUMIDITIES FALL TO UNDER 30 PERCENT. WITH STRONGER SOUTHWEST WINDS TODAY...AHEAD OF THE FRONTAL BOUNDARY...THIS COULD CREATE A PERIOD OF DANGEROUS FIRE WEATHER CONDITIONS. THIS THREAT WILL HIGHLIGHTED IN THE HWO AND FIRE WEATHER PLANNING FORECAST. HIGHS TODAY WILL CLIMB EVEN HIGHER INTO THE LOW TO MID 70S...EXCEPT IN THE NORTH...WHERE CLOUDS AND PERHAPS PRECIPITATION MAY KEEP LOCATIONS IN THE 60S. FRONTAL BOUNDARY WILL SLOWLY DRIFT BACK TO THE NORTH THIS EVENING...WITH RAIN CHANCES DECREASING FROM SOUTH TO NORTH. SKIES SHOULD REMAIN MOSTLY TO PARTLY CLEAR OVERNIGHT...ALLOWING SOME VALLEY LOCATIONS TO DECOUPLE AND FALL BACK INTO THE 40S...WHILE RIDGES STAY IN THE 50S. ANOTHER VIGOROUS SHORTWAVE WILL TRACK NORTHEAST THROUGH THE PLAINS ON MONDAY...FURTHER PUSHING THE BOUNDARY TO THE NORTH AND KEEPING EASTERN KENTUCKY DOMINATED BY STRONG RIDGING. A VERY WARM DAY IS ON TAP WITH HIGHS SURGING WELL INTO THE 70S AREAWIDE. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 255 AM EDT SUN APR 7 2013 MODELS CONTINUE TO SHOW GENERAL AGREEMENT EARLY IN THE PERIOD IN TERMS OF HOW SYSTEMS WILL AFFECT OUR LOCAL WEATHER. PATTERN AMPLIFICATION WILL BE ONGOING...WITH A WESTERN CONUS UPPER TROUGH AND AND A SOUTHEAST CONUS UPPER RIDGE. STRONG SURFACE LOW PRESSURE WILL TRACK FROM CO AT THE START OF THE PERIOD TO THE VICINITY OF IL/IN BY THURSDAY MORNING. A FRONTAL BOUNDARY EXTENDING EAST FROM THE LOW WILL BE LAID OUT NORTH OF THE OHIO RIVER. MODELS DISAGREE ON EXACTLY HOW FAR NORTH/SOUTH IT WILL BE POSITIONED. THE ECMWF MANAGES TO BRING IT FURTHER SOUTH THAN ANY OTHER MODEL...MAKING IT INTO THE NORTHERN PART OF THE JKL FORECAST AREA BY 12Z THURSDAY. WITH ALL OTHER GUIDANCE SHOWING IT FURTHER NORTH...WILL GO WITH A FORECAST THAT KEEPS OUR AREA IN THE WARM SECTOR. A BROAD ZONE OF WARM AIR ADVECTION WILL BRING MOISTURE NORTH FROM THE GULF OF MEXICO AND LIFT IT ACROSS THE FRONT. THE BEST CHANCE OF RAIN WITH THIS WILL BE WELL TO OUR NORTH...BUT CAN NOT RULE OUT SOME SHOWERS MAKING IT INTO THE NORTHERN PART OF THE AREA. THE FORECAST BECOMES MORE PROBLEMATIC LATER IN THE WEEK DUE TO CONTINUED DIFFERENCES IN MODEL TIMING OF THE SURFACE LOW AND ITS TRAILING COLD FRONT. THE ECMWF IS THE SLOWEST...WITH LOCAL FROPA NOT HAPPENING UNTIL FRIDAY AFTERNOON. THE END OF THE NAM RUN ON WED MORNING LOOKS SIMILAR TO THE GFS...WHICH ENDS UP WITH FROPA DURING THE DAY THURSDAY. THERE ARE SOME MEMBERS OF THE GFS ENSEMBLE WHICH SHOW SIMILAR TIMING AS THE ECMWF...BUT THE GFS ENSEMBLE MEAN IS MORE SUPPORTIVE OF THE OPERATIONAL GFS. WILL FAVOR A COMPROMISE SOLUTION CLOSER TO THE GFS. WITH THAT SAID...HIGHEST POPS...IN LIKELY CATEGORY...WILL BE ON THURSDAY AND THURSDAY NIGHT. WILL USE HIGH CHANCE ON FRIDAY TO LEND SOME CREDENCE TO THE ECMWF. ALL MODELS SHOW INSTABILITY AHEAD OF THE COLD FRONT...AND A CHANCE OF THUNDER WILL BE USED WITH THE APPROACH AND PASSAGE OF THE COLD FRONT. WINDS ALOFT LOOK TO BE QUITE STRONG...AND WOULD SUPPORT SEVERE WX. HOWEVER...THE DEGREE OF INSTABILITY DOES NOT REALLY STAND OUT. THE SET-UP WILL NEED TO CONTINUE TO BE WATCHED. THE WARMEST AIR MASS OF THE SEASON SO FAR WILL BE IN PLACE UP UNTIL COLD FROPA. NEEDLESS TO SAY...FRONTAL TIMING WILL PLAY A KEY ROLE IN TEMPS LATE IN THE PERIOD...AND LEADS TO A LOWER CONFIDENCE IN THE TEMPERATURE FORECAST FOR THURSDAY INTO FRIDAY...AND A POTENTIAL FOR MORE SIZEABLE ERRORS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 658 AM EDT SUN APR 7 2013 VFR CONDITIONS WILL HOLD ON THROUGH THE PERIOD. AN APPROACHING COLD FRONT WILL MOVE INTO NORTHERN KENTUCKY TODAY. SOME SCATTERED SHOWERS AND A FEW THUNDERSTORMS ARE POSSIBLE...MAINLY NORTH OF I-64. LOWER CLOUDS AND PRECIPITATION WILL NOT LIKELY MAKE IT SOUTH OF I-64...KEEPING THE TAF SITES DRY WITH JUST SOME HIGH CLOUDS TO CONTEND WITH. && .FIRE WEATHER... ISSUED AT 1051 AM EDT SUN APR 7 2013 DEWPOINTS HAVE BEEN RISING IN THE INCREASING SOUTHWEST FLOW...AND DESPITE RELATIVE HUMIDITY CURRENTLY IN THE 30 TO 40 PERCENT RANGE OVER SOUTHEAST KY...WE SHOULD SEE RELATIVE HUMIDITY STAY ABOVE CRITICAL THRESHOLDS. HOWEVER SOME SPOTS WILL BE NEAR 25 PERCENT RH THIS AFTERNOON. THIS WILL BE MONITORED CLOSELY AS WINDS ARE MUCH STRONGER THAN YESTERDAY...WITH GUSTS TO 30 MPH EXPECTED FOR THIS AFTERNOON. HAVE ISSUED AN SPS FOR ENHANCED WILD FIRE THREAT. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SBH SHORT TERM...KAS LONG TERM...HAL AVIATION...KAS FIRE WEATHER...SBH
AREA FORECAST DISCUSSION
NWS GRAY ME
433 PM EDT SUN APR 7 2013 .SYNOPSIS... LOW PRESSURE CROSSING SOUTHERN CANADA WILL DRAG A COLD FRONT THROUGH THE REGION OVERNIGHT. A WEAK AREA OF HIGH PRESSURE WILL BUILD OVER THE REGION ON MONDAY. ANOTHER AREA OF LOW PRESSURE WILL HEAD EAST FROM THE GREAT LAKES MONDAY NIGHT AND WILL MOVE THROUGH SOUTHERN NEW ENGLAND AND OUT TO SEA ON TUESDAY. LOW PRESSURE WILL ONCE AGAIN APPROACH FROM THE WEST TUESDAY NIGHT LIFTING A WARM FRONT INTO CENTRAL NEW ENGLAND ON WEDNESDAY WHERE IT WILL STALL. LOW PRESSURE MOVING NORTHEAST THROUGH THE ST LAWRENCE VALLEY WILL LIFT THE WARM FRONT INTO NORTHERN NEW ENGLAND ON THURSDAY. A TRAILING COLD FRONT WILL CROSS THE AREA THURSDAY NIGHT AND WILL SLOWLY PUSH OFFSHORE ON FRIDAY. HIGH PRESSURE WILL BUILD IN FROM THE WEST SATURDAY THROUGH SUNDAY. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... UPDATE... HAVE UPDATED GRIDS TO ACCOUNT FOR CURRENT CONDITIONS. WINDS CONTINUE TO GUST BETWEEN 20 AND 30 MPH ACROSS THE FORECAST AREA...WITH HIGHEST GUSTS ALONG THE EXPOSED COASTLINE...AND ALSO OVER IN NH WHERE TEMPERATURES CLIMBED WELL INTO THE 50S. HAVE REMOVED FZRA FROM TNGTS FCST AS GROUND TEMPS SEEM A LITTLE TOO WARM WITH READINGS CURRENTLY IN THE 50S IN THE MTNS. HAVE ALSO USED THE "SHOWERIZE" TOOL FOR TNGTS PCPN. LATEST RUC SOLUTION PICKS UP ON CONVECTIVE LINE ALONG THE VT/NH BORDER (AS OF 2032Z) VERY WELL. HOWEVER...THIS LINE OF PCPN SHOULD WEAKEN SIGNIFICANTLY AS IT ENTERS THE REGION OF MUCH LOWER SURFACE DEW POINTS. HAVE ADJUSTED DEW POINTS BASED ON CURRENT CONDITIONS. ALSO...USED CLOUD COVER FROM STLT FOR THE INTIAL CONDS AS CLOUD DECKS ARE RAPIDLY CHANGING. PREV DISC... LOW PRESSURE CROSSING SOUTHERN CANADA WILL DRAG A COLD FRONT THROUGH THE REGION OVERNIGHT. SHOWERS AND A FEW THUNDERSTORMS CURRENTLY PUSHING THROUGH EASTERN NEW YORK AHEAD OF THE FRONT AND THIS LINE WILL BRING THE BEST CHANCE OF PRECIP TO THE REGION DURING THE EVENING HOURS. MAY SEE SOME SLEET OR SNOW GRAINS MIXING IN IN THE NORTH BUT NOT LOOKING FOR ANY ACCUMULATIONS. SHOULD SEE PARTIAL CLEARING DOWNWIND OF THE MOUNTAINS DURING THE EARLY MORNING HOURS WHILE CLOUDS PERSIST IN THE NORTH. WILL SEE A RELATIVELY MILD NIGHT WITH LOWS IN THE LOWER TO MID 30S NORTH AND UPPER 30S TO LOWER 40S IN THE SOUTH. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... MOUNTAIN CLOUDS WILL GRADUALLY DIMINISH MONDAY MORNING AND SHOULD SEE MOSTLY SUNNY SKIES ACROSS THE REGION BY AFTERNOON AS A WEAK RIDGE OF HIGH PRESSURE BUILDS OVER THE REGION. WILL SEE TEMPS REBOUND TO ABOVE NORMAL...ALTHOUGH EXPECT AN AFTERNOON SEA BREEZE TO CAP HIGHS IN THE MID TO UPPER 50S IN COASTAL AREAS. WARMER SOUTHERN INTERIOR SECTIONS WILL ENJOY HIGHS IN THE LOWER TO MID 60S. RAPID FIRE PROCESSION SHORTWAVES WILL CONTINUE MONDAY NIGHT AS LOW PRESSURE QUICKLY HEADS EAST FROM THE GREAT LAKES. CLOUDS WILL OVERSPREAD THE REGION FROM WEST TO EAST DURING THE EVENING HOURS WITH RAIN MOVING INTO MUCH OF THE REGION AROUND MIDNIGHT. MAY SEE ENOUGH COOLING FOR RAIN TO MIX WITH SLEET OR SNOW IN THE NORTH WHERE AN INCH OR TWO OF WET SNOW MAY ACCUMULATE OVER THE HIGHER TERRAIN. WILL ONCE AGAIN SEE MILD OVERNIGHT LOWS WITH MID TO UPPER 30S NORTH AND UPPER 30S TO LOWER 40S SOUTH. && .LONG TERM /TUESDAY THROUGH SUNDAY/... SFC LOW TRACKS ACROSS THE FCST AREA TUESDAY WITH RA/SHRA THRU THE MORNING IN NH AND MIDDAY OVER ME...THEN AS THE LOW MOVES QUICKLY TO THE E CLEARING FOLLOWS FROM W TO E. A TRAILING FNT DEVELOPS W OF THE LOW ACROSS THE FCST AREA AND FURTHER TO THE W TUESDAY NGT. THIS FNT SEPARATES MUCH WARMER AIR TO THE S FROM MUCH COLDER AIR TO THE N. THE FNT SAGS SLOWLY TO THE S ON WEDNESDAY WITH VERY WEAK LOW PRES SLIDING TO THE E ALONG THE BOUNDARY. THE FNT WAVERS WEDNESDAY NGT THRU THURSDAY NGT AS OTHER WEAK LOWS TRACK EASTWARD ALONG IT. THE EXACT LOCATION OF THE FNT VARIES AMONGST THE MODELS WITH THE ECMWF THE COLDEST WITH THE BOUNDARY TO OUR S, GFS THE WARMEST WITH THE FNT JUST TO OUR N AND THE CMC MODEL IN BETWEEN THOUGH CLOSER TO THE GFS. EITHER WAY THE SYSTEM WILL GIVE US A PERIOD OF WET WX...MOSTLY RA...THOUGH SOME MIX OR MAYBE SN OVER FAR NORTHERN AND MOUNTAIN ZONES PSBL. THE GFS WARMS US UP CONSIDERABLY WITH H8 TEMPS OF PLUS 10 TO NEARLY PLUS 15. THIS APPEARS OVERDONE THOUGH THE ECMWF WHICH IS MUCH COLDER MAY ALSO BE OVERDONE... SO A COMPROMISE IS IN ORDER. FINALLY THE LAST LOW MOVES E ON FRIDAY WITH A TRAILING CD FNT ALSO PUSHING TO THE E. TIMING OF THIS SYSTEM STILL TO EARLY TO DETERMINE WHETHER OR NOT WE SEE PRCP FOR MOST OF THE DAY OR IF IT COMES TO AN END EARLIER ON. ALSO...THE ECMWF IS TRACKING THE LOW TO OUR S RATHER THAN OVER US LIKE THE GFS THUS THE ECMWF MODEL PROVIDES A BETTER CHC FOR MIXED/SN EVENT ON FRIDAY. BEHIND THIS SYSTEM STRONG GUSTY NW WINDS USHER IN COLDER AND DRIER AIR FRIDAY NGT AND SATURDAY. HIGH PRES BUILDS IN ON SUNDAY WITH WEAKER WINDS AND WARMING TEMPS AS THE AIR MASS MODERATES. GENERALLY USED BLEND OF ECMWF, GFS40, NAM, HPC GUIDANCE, GMOS AND MEX MOS AND WNA4 FOR SEAS FOR THE LONG TERM FCST. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... SHORT TERM...AREAS OF MVFR/IFR CEILINGS TONIGHT...BECOMING VFR ON MONDAY. MORE MVFR/IFR CEILINGS DEVELOPING AFTER MIDNIGHT MONDAY NIGHT. LONG TERM /TUESDAY THROUGH FRIDAY/...AN LENGTHY PERIOD OF UNSETTLED WET WEATHER THRU THE LONG TERM PERIOD AS A FRONTAL BOUNDARY STAYS NEARBY WHILE LOW PRES SYSTEMS TRACK E ALONG IT. THUS FREQUENT IFR/LIFR CONDITIONS PSBL TUESDAY THRU FRIDAY. && .MARINE... SHORT TERM...CONTINUING SCA`S THROUGH TONIGHT. LONG TERM /TUESDAY THROUGH FRIDAY/... UPDATE... HAVE EXTENDED THE SCAS INTO MONDAY FOR THE OUTER WATERS. THIS IS MAINLY DUE TO SEAS. PREV DISC... CONDITIONS MAINLY BELOW SCA LEVELS TUESDAY THRU WEDNESDAY NGT AS FNT REMAINS NEARBY AND PRES GRADIENT FAIRLY WEAK AS WEAK LOW PRES MOVES ALONG THE FNT. THURSDAY THRU FRIDAY...DEPENDING ON THE MODEL SOLUTION... THERE IS THE POTENTIAL FOR A MORE SIGNIFICANT LOW TO FORM WHICH WOULD INCREASE WINDS AND BUILD SEAS POSSIBLY TO SCA LEVELS...OR MAYBE INTO MINIMAL GALE FORCE OVER THE OUTER WATERS. && .FIRE WEATHER... RAIN SHOWERS WILL HELP TO DAMPEN FIRE DANGER OVERNIGHT. WARMER TEMPS AND HIGHER DEW POINTS WILL KEEP THE REGION ABOVE RED FLAG CRITERIA MONDAY WITH ANOTHER ROUND OF SHOWERS COMING THROUGH MONDAY NIGHT. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT MONDAY FOR ANZ150>154. && $$ JC
AREA FORECAST DISCUSSION
NWS SPRINGFIELD MO
1242 PM CDT SUN APR 7 2013 .MESOSCALE DISCUSSION... ISSUED AT 1241 PM CDT SUN APR 7 2013 MOISTURE CONTINUES TO SLOWLY INCREASE FROM SOUTHWEST TO NORTHEAST INTO THE REGION. NOTICEABLY MORE HUMID WITH DECENT CUMULUS DEVELOPMENT NOTED OVER THE PAST FEW HOURS. MID LEVEL FEATURES ARE A BIT MESSY AT THIS POINT...WITH A MORE DEFINITIVE SHORTWAVE OBSERVED VIA RAP INITIALIZATIONS ACROSS WESTERN PORTIONS OF OKLAHOMA AND KANSAS. THIS FEATURE WILL BE MONITORED AS A TRIGGERING MECHANISM FOR CONVECTION THIS AFTERNOON. EXPECTATIONS ARE FOR A GENERAL INCREASE IN CONVECTIVE DEVELOPMENT AND COVERAGE AS THE AFTERNOON PROGRESSES...WITH BETTER CHANCES FOR THE WESTERN HALF OF THE OUTLOOK AREA DURING THE MID/LATE AFTERNOON HOURS. MLCAPE IN THE 1000 TO 1250 J/KG RANGE AND MUCAPE AROUND 1500 J/KG IS EXPECTED THIS AFTERNOON. WITH DEEP LAYER SHEAR ON THE AROUND OF 40 OR SO KNOTS...STORM MODE FAVOR SUPERCELLULAR STRUCTURES (THOUGH A MIX OF MULTICELLS/LINE SEGMENTS IS PLAUSIBLE AS WELL). SLIGHT RISK UPDATED AT MIDDAY BY SPC IS WELL PLACED AND WITH HAIL BEING THE MAIN RISK. CANNOT RULE OUT LOCALIZED DAMAGING WIND GUSTS. LATEST AVAILABLE 12Z MODEL OUTPUT AND MESOSCALE MODELS CONTINUE TO DIFFER ON THE EVOLUTION OF CONVECTION THIS EVENING INTO THE OVERNIGHT HOURS...THOUGH THE TREND OF HAVING STORMS FOCUSING PROGRESSIVELY TO THE NORTH OF THE AREA IS THE OVERALL TREND. WILL CONTINUE TO REFINE SPECIFIC EXPECTATIONS FOR THE OVERNIGHT FORECAST SHORTLY. && .SHORT TERM...(TODAY THROUGH MONDAY NIGHT) ISSUED AT 307 AM CDT SUN APR 7 2013 WEAK FRONTAL BOUNDARY HAD PUSHED INTO NORTHERN MISSOURI EARLY THIS MORNING. IT HAD SET OFF A FEW SHOWERS OVER MAINLY EAST CENTRAL MISSOURI EARLIER IN THE EVENING BUT THOSE HAVE SINCE DISSIPATED. THIS BOUNDARY SHOULD PUSH INTO SOUTHERN MISSOURI LATER THIS MORNING AND WILL ACT AS A FOCUS FOR THUNDERSTORM ACTIVITY LATER IN THE DAY. A SHORT WAVE COMING OUT OF THE ROCKIES WILL ALLOW THIS FRONT TO STALL OUT AND PUSH BACK NORTHWARD AS A WARM FRONT. MOISTURE WILL BE ON THE INCREASE AS WELL WITH DEW POINTS CLIMBING INTO THE MID 50S BY THIS AFTERNOON. MUCAPES SHOULD BE CLOSE TO 2000 J/KG LATE THIS AFTERNOON WITH 0-6KM SHEAR VALUES AROUND 40 KTS. THIS SHOULD GET STORMS GOING LATE THIS AFTERNOON WITH A CONTINUATION INTO THE EVENING HOURS AS THE LOW LEVEL JET INCREASES. BELIEVE THAT THE PRIMARY THREAT WILL BE LARGE HAIL ALTHOUGH WINDS CANNOT BE RULED OUT AS WELL IF WE GET SUPERCELLS. MONDAY WILL BE A DIFFERENT STORY. A FAIRLY STRONG ELEVATED MIXED LAYER WILL BE IN PLACE WHICH WILL TEND TO CAP THE ATMOSPHERE OVER THE REGION. HAVE THEREFORE KEPT POPS IN THE SLIGHT CHANCE CATEGORY FOR MONDAY. HIGH TEMPERATURES SHOULD HAVE NO TROUBLE MAKING IT INTO THE 70S WITH THE AREA IN THE WARM SECTOR. WITH THE ADDITION OF THE GULF MOISTURE...OVERNIGHT LOWS WILL BE RATHER MILD JUST MAKING IT INTO THE MID TO UPPER 50S. .LONG TERM...(TUESDAY THROUGH SATURDAY) ISSUED AT 307 AM CDT SUN APR 7 2013 THE MAIN CONCERN WILL BE SEVERE WEATHER AND HEAVY RAIN CHANCES LATE TUE THROUGH WED. AN UPPER LEVEL JET NOW JUST OFF THE THE U.S. PAC NW COAST AND BRITISH COLUMBIA WILL DIG SOUTHEAST INTO THE SW U.S...CLOSE TO THE FOUR CORNERS REGION BY 12Z TUE. THE GENERAL MODEL CONSENSUS IS THAT A LONG WAVE POSITIVELY TILTED TROUGH AXIS WILL EXTEND FROM THE DAKOTAS TO NEW MEXICO BY MIDDAY WED LEAVING OUR AREA IN A REGION OF SW FLOW ALOFT. A STRONG CAP/EML WILL BE IN PLACE TUE. MID LEVEL HEIGHT FALLS/COOLING AND LIFT WITH THE APPROACHING UPPER LEVEL SYSTEM SHOULD ALLOW STORMS TO DEVELOP ALONG THE DRY LINE OVER CENTRAL KS/WESTERN OK TUE AFTERNOON...AND WITH TIME THIS CONVECTION WILL SPREAD EAST INTO EASTERN KS AND WESTERN MO LATE TUE OR TUE EVENING. THE GFS AND GEM CONTINUE TO BE FASTER IN BRINGING THE SFC COLD FRONT INTO THE REGION...6-12 HOURS FASTER THAN THE ECMWF...SO TIMING AND DETAILS ARE STILL UP IN THE AIR. GIVEN SW FLOW ALOFT NOT SURE HOW LONG CONVECTION CAN REMAIN DISCRETE BEFORE FILLING IN AND BECOME MORE OF A LINEAR CLUSTER(S)/COMPLEX...BUT GENERAL SHEAR AND INSTABILITY SUPPORT A CONTINUED MENTION OF A CHANCE FOR SEVERE WX. THE WAVY SFC FRONT MAY LINGER OVER THE MS VLY TO PRODUCE PERIODS OF POST FRONTAL HEAVIER SHOWERS/TSTMS WED BEFORE CHILLY AIR ONCE AGAIN MAKES ANOTHER APPEARANCE WED NIGHT AND THU. A N-S ORIENTED SFC RIDGE WILL SHIFT THROUGH THE AREA LATE IN THE WEEK WITH GENERALLY DRY...COOL...AND QUIET WEATHER. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1241 PM CDT SUN APR 7 2013 FOR THE 18Z TAFS (JLN/SGF/BBG)...PRIMARY FORECAST CONCERN IS THE POTENTIAL FOR SCATTERED THUNDERSTORMS FROM THE MIDDLE OF THIS AFTERNOON THROUGH THIS EVENING. CONFIDENCE IN EXACT COVERAGE IS STILL LOW...AND HAVE OPTED TO USE VCTS AT JLN AND SGF FOR THE TIME BEING UNTIL CONFIDENCE INCREASES. HAVE KEPT BBG DRY FOR NOW...AN ISOLATED SHOWER OR STORM CANNOT BE RULED OUT HERE...HOWEVER IT APPEARS THE BETTER OPPORTUNITY FOR ACTIVITY WILL BE TO THE NORTHWEST OF THE BBG AERODROME. CHANCES FOR STORMS WILL PERSIST THROUGH THIS EVENING...WITH THE FOCUSING LIFTING NORTH OF THE AERODROMES OVERNIGHT TONIGHT. LOW LEVEL WIND SHEAR WILL BE PREVALENT TONIGHT AS A MODERATE LOW LEVEL JET SPREADS OVER THE REGION. LAMP AS WELL AS MAV/MET MOS GUIDANCE CONTINUE TO HINT AT IFR CIG DEVELOPMENT AT ALL TAF SITES THIS EVENING AND PERSISTING INTO MONDAY. UPSTREAM OBS IN OKLAHOMA DID FLIRT WITH IFR STRATUS AT TIMES...THOUGH NOT QUITE READY TO BITE OFF ON WIDESPREAD IFR AFTER LOOKING AT THE SREF PROBABILITIES. HAVE MAINTAINED DEVELOPMENT OF LOW END MVFR CIGS. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ MESOSCALE...GAGAN SHORT TERM...GAEDE LONG TERM...DSA AVIATION...GAGAN
AREA FORECAST DISCUSSION
NWS BILLINGS MT
310 PM MDT SUN APR 7 2013 .SHORT TERM...VALID FOR MON AND TUE... WINTER WEATHER EVENT COMING TONIGHT INTO TUESDAY...WITH STRONG COLD FRONTAL PASSAGE LATER TONIGHT. MUST CONTINUE TO STRESS GREAT UNCERTAINTY IN THE DETAILS. THERE ARE TWO PHASES WITH THIS EVENT. PHASE ONE INVOLVES FRONTOGENETIC PCPN AS PACIFIC SHORTWAVE INTERACTS WITH CANADIAN COLD FRONT...BEGINNING LATER THIS EVENING AND LASTING INTO MONDAY. THIS WILL NOT BE AN UPSLOPE EVENT AS PCPN WILL BE DRIVEN AT THE MID LEVELS...WITH BEST FORCING ACROSS OUR NORTH. TREMENDOUS MODEL DIFFERENCES EXIST HERE...WITH NAM AND RAP KEEPING STRONGER FRONTOGENESIS TO OUR NORTH...AND THE GFS/EC WRAPPING PCPN FURTHER SOUTH AS MID LEVEL BAROCLINICITY DOES LIKEWISE. TOUGH FORECAST HERE. BELIEVE ENERGY MOVING FROM SOUTHEAST OR INTO SOUTHERN ID IS DYNAMIC AND FAR ENOUGH SOUTH TO ALLOW FOR A SOUTHERN PUSH OF FORCING TO AN EXTENT GREATER THAN THE NAM/RAP...BUT NOT TO THE EXTENT OF THE GFS WHICH SEEMS MUDDLED BY CONVECTIVE FEEDBACK. INSTABILITY IS ANOTHER IMPORTANT FACTOR AS AIRMASS WILL BE FAIRLY UNSTABLE THROUGH THE NIGHT...AGAIN SEE CONVECTIVE ACTIVITY UPSTREAM NOW. SO...HAVE ISSUED WINTER WX ADVISORIES ACROSS OUR NORTH FROM WHEATLAND TO FALLON COUNTIES...NORTH OF BILLINGS BUT INCLUDING HIGHWAY 12 AND A PORTION OF I-94. GUSTY NORTH WINDS WITH THE COLD ADVECTION WILL PRODUCE BLOWING SNOW ALONG WITH THE ACCUMULATION...WHICH SHOULD GENERALLY RANGE FROM 1 TO 3 INCHES... WITH MORE NORTH OF OUR CWA. AS FOR THE CITY OF BILLINGS...MAYBE A LITTLE ACCUMULATION AFTER MIDNIGHT BUT FEEL BRUNT OF PCPN WILL REMAIN NORTH...THOUGH WILL SEE SCATTERED PREFRONTAL RAIN SHOWERS AND ISOLATED TSTMS THIS EVENING. EXPECT UPSLOPE SNOW SHOWERS WITH LESS THAN AN INCH ON MONDAY IN THE METRO AREA...WITH GUSTY WINDS AND A GENERALLY COLD DAY. AS A SIDE NOTE...IF MID LEVELS STAY DRY FROM BILLINGS SOUTH TONIGHT...COULD BE SOME LIGHT FREEZING DRIZZLE ONCE TEMPS FALL BELOW FREEZING AND LOW LEVELS MOISTEN WITH UPSLOPE NE WINDS DEVELOPING. WILL NEED TO KEEP WATCH OF THIS. PHASE TWO WILL BE INFLUENCED BY THE EVOLUTION OF PHASE ONE. THIS WILL INVOLVE DEEP CENTRAL ROCKIES CLOSED LOW AS WE WILL BE NEAR ITS NORTHERN EXTENT. A SOUTHERN PUSH OF FRONTOGENESIS TONIGHT WOULD LIKELY RESULT IN A MORE SOUTHERN TRACK OF THE UPPER LOW...WITH OUR AREA MORE INFLUENCED BY WEAKER/DRY NORTHERN TROF CURRENTLY IN SOUTHERN CANADA. IF STRONGER FORCING STAYS NORTH TONIGHT THAN WE COULD EXPECT A MORE NORTHWARD TRACK OF THE UPPER LOW...AND STRONGER DIFFLUENCE OVER US...AND BETTER SNOW POTENTIAL FOR OUR SOUTHERN UPSLOPE AREAS AND SOUTHEAST MT...AS THE ECMWF HAS BEEN CONSISTENT IN SUGGESTING. LATEST GFS KEEPS THE LOW ENTIRELY TO OUR SOUTH...SO PLENTY OF UNCERTAINTY HERE AS WELL. WILL KEEP A MIDDLE GROUND...WITH LIKELY POPS AND SOME ACCUMULATION ACROSS OUR SOUTH MONDAY NIGHT AND TUESDAY. WITH A MORE NORTHERN TRACK...DEEP DENDRITIC LAYER AND UPSLOPE FLOW COULD BRING A SIGNIFICANT SNOW EVENT TO SUCH PLACES AS SHERIDAN...BROADUS AND ALZADA...WITH PCPN LASTING INTO TUESDAY NIGHT. OR WITH THE SOUTHERN TRACK THESE AREAS WOULD RECEIVE VERY LITTLE PCPN WITH AN END BY TUESDAY. PLEASE MONITOR THE FORECAST OVER THE NEXT DAY AS ADJUSTMENTS WILL LIKELY BE NEEDED. AS FOR THE CITY OF BILLINGS...IT DOES NOT LOOK AS IF WE WILL RECEIVE MUCH SNOWFALL WITH PHASE TWO EITHER...AND POSSIBLY NONE. AGAIN THIS WILL DEPEND ON EXACT TRACK OF THE UPPER LOW. CANADIAN AIRMASS IS QUITE COLD AND TEMPS WILL BE WELL BELOW NORMAL THE NEXT TWO DAYS. HAVE DROPPED EXPECTED TEMPS A BIT MORE. RECORD LOWS COULD BE CHALLENGED AT BILLINGS AND MILES CITY MONDAY NIGHT. JKL .LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN... CONSENSUS OF THE EXTENDED IS FOR SLIGHTLY BELOW SEASONAL AVERAGES FOR TEMPERATURES AND AN UNSETTLED NATURE FOR POPS. THE ONLY REAL DRY DAY APPEARS TO BE WEDNESDAY AS A SHORT LIVED MESO RIDGE MOVES IN. A DEEP UPPER TROUGH OVER THE GULF OF ALASKA AND THE NORTHERN TERRITORIES DROPS SOUTHWARD TOWARD THE PACIFIC NORTHWEST THIS WEEKEND. THIS PROCESS WILL CAUSE FALLING HEIGHTS FOR A RELATIVELY UNSTABLE ATMOSPHERE WITH MOISTURE AND SHORTWAVES SHOOTING ACROSS THE FORECAST AREA. IMPOSSIBLE AT THIS POINT TO PIN POINT THE BEST DAY FOR POP CHANCES AS EXACT PLACEMENT OF APPROACHING WAVES WILL BE CRITICAL FOR ASCENT. A BROAD BRUSHED SLIGHT CHANCE TO CHANCE POPS SEEMS THE BEST WAY TO GO. THE WARMEST DAY SHOULD BE WEDNESDAY WITH LESS CLOUD COVER ALLOWING A HIGH SUN ANGLE TO WORK. TWH && .AVIATION... SCATTERED SHOWERS WILL PUSH ACROSS THE AREA LATE THIS AFTERNOON AND THIS EVENING. SOME WIND GUSTS TO 30KTS WILL ACCOMPANY THE SHOWERS WITH MAINLY LIGHT RAIN. A STRONG COLD FRONT WILL PUSH INTO NORTHERN TERMINALS THIS EVENING AND INTO SOUTHERN TERMINALS OVERNIGHT. THIS FRONT WILL SWITCH WINDS TO THE NORTH WITH GUSTS TO 30KTS. RAIN AND SNOW WILL DEVELOP MAINLY NORTH OF A LIVINGSTON TO BILLINGS TO BAKER LINE THIS EVENING. THE PRECIPITATION WILL CHANGE TO SNOW BY LATE EVENING AND CONTINUE OVERNIGHT WITH CONDITIONS LOWERING TO IFR NORTH OF THIS LINE. LOW CLOUDS WILL SPREAD SOUTH OVERNIGHT WITH CEILINGS LOWERING TO MVFR CATEGORIES. LIGHT SNOW...AND POSSIBLY LIGHT FREEZING DRIZZLE...WILL ACCOMPANY THE LOWERING CEILINGS. LOW CLOUDS...SNOW AND GUSTY NORTH WINDS WILL CONTINUE THROUGH MONDAY MORNING. TWH && .PRELIMINARY POINT TEMP/POPS... MON TUE WED THU FRI SAT SUN ----------------------------------------------------------- BIL 028/034 018/036 022/048 033/056 033/053 032/053 029/052 67/S 31/B 01/B 33/W 22/W 33/W 33/W LVM 028/039 018/038 022/048 032/053 029/051 029/050 026/049 66/S 41/B 01/B 32/W 22/W 33/W 33/W HDN 030/035 019/035 019/047 029/057 028/054 027/054 026/054 67/S 41/B 11/B 33/W 22/W 33/W 33/W MLS 030/032 016/033 018/044 027/052 027/052 028/052 025/052 88/S 21/B 11/B 23/W 22/W 33/W 32/W 4BQ 033/036 017/031 016/041 024/052 024/051 026/051 024/051 57/S 63/S 21/B 23/W 22/W 33/W 33/W BHK 030/031 015/029 015/038 022/045 027/046 026/046 021/046 78/S 42/S 11/B 23/W 22/W 23/W 32/W SHR 032/037 020/031 015/043 026/054 027/051 027/052 024/051 28/S 75/S 21/B 23/W 22/W 23/W 33/W && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...WINTER WEATHER ADVISORY IN EFFECT FROM 9 PM THIS EVENING TO NOON MDT MONDAY FOR ZONES 28-29-42-63. WINTER WEATHER ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 6 PM MDT MONDAY FOR ZONES 31>33. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1232 PM CDT SUN APR 7 2013 .UPDATE... ISSUED AT 1223 PM CDT SUN APR 7 2013 CLEARED THE FREEZING RAIN ADVISORY ALL BUT JAMES RIVER VALLEY. UPDATE ISSUED AT 953 AM CDT SUN APR 7 2013 MAINLY CHANGES EARLY THIS MORNING...NOW GETTING SNOW FROM MINOT AND EAST. THE PRECIPITATION HAS MOVED EAST OF WILLISTON AND STANLEY. ALSO WARMING TEMPERATURES SOUTH CENTRAL KEEPING THE PRECIPITATION AS RAIN. CANCELLED THE FREEZING RAIN ADVISORY FOR ALL BUT MCLEAN COUNTY THROUGH NOON...AND EAST THROUGH HARVEY AND SOUTH THROUGH THE JAMES RIVER VALLEY THROUGH 7 PM. UPDATE ISSUED AT 708 AM CDT SUN APR 7 2013 UPDATE THIS MORNING MAINLY FOR TEMPERATURES. LOW PRESSURE OVER EASTERN MONTANA WITH HIGH PRESSURE OVER EASTERN NORTH DAKOTA EARLY THIS MORNING WITH A SOUTHEAST FLOW OVER WESTERN NORTH DAKOTA AND LIGHT WINDS IN THE CENTRAL. EXTENSIVE MVFR-IFR STRATUS ACROSS ALL OF WESTERN AND CENTRAL NORTH DAKOTA. THIS HAS KEPT TEMPERATURES FROM FALLING AS FAR AS FORECAST...AND DO NOT EXPECT TEMPERATURES TO DROP MUCH MORE THIS MORNING. THUS RAISED EARLY MORNING TEMPERATURES IN THE EAST FROM THE LOW TO MID 20S INTO THE UPPER 20S. BAND OF PRECIPITATION IS MOVING THROUGH THE WEST AND INTO CENTRAL NORTH DAKOTA. REPORT OF SOME MIXED PRECIPITATION AT WILLISTON AND A LITTLE UNDER AN INCH OF SNOW. THE WARMER THAN EXPECTED TEMPERATURES COMBINED WITH ROAD SURFACE TEMPERATURES AT OR ABOVE FREEZING IN MANY AREAS...SHOULD HELP TO DIMINISH THE EFFECTS OF ANY FREEZING RAIN. HOWEVER...EXPECT SECONDARY ROADS... SIDEWALKS AND PARKING LOTS MAY YET BECOME SLIPPERY. WILL HOLD OFF ON ANY UPDATES TO THE CURRENT FREEZING RAIN ADVISORY AND SEE IF WE CAN GET A FEW MORE REPORTS AFTER SUNRISE. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 329 AM CDT SUN APR 7 2013 THE MAIN FORECAST CHALLENGES FOR THE SHORT TERM INCLUDE PRECIPITATION TIMING AND TYPE. THE 00Z MODEL SUITE IS IN AGREEMENT...THUS HAVE UTILIZED A BLEND OF GUIDANCE. LATEST RADAR IMAGERY AT 330 AM CDT IS SHOWING SOME SCATTERED LIGHT RETURNS ACROSS THE SOUTHWEST....AND MORE WIDESPREAD LIGHT RETURNS OVER NORTHEASTERN MONTANA ASSOCIATED WITH A WEAK UPPER LEVEL IMPULSE. HOWEVER...SURFACE OBSERVATIONS HAVE NOT REFLECTED PRECIPITATION REACHING THE GROUND OVER THE SOUTHWEST. THE 05/06Z RAP SOLUTIONS DO NOT REFLECT THE LIGHT PRECIPITATION OVER THE NORTHEAST AT THIS TIME...BUT IT DOES PAINT SOME LIGHT PRECIPITATION ACROSS THE SOUTHWEST. THE 00Z GFS/ECMWF/NAM ALL SHOW LIGHT PRECIPITATION OVER NORTHEAST MONTANA AT THIS TIME...AND THUS HAVE UTILIZED A BLEND OF THE 00Z MODEL GUIDANCE IN ADDITION TO THE 05/06Z RAP GUIDANCE. PRECIPITATION WILL CONTINUE TO SPREAD EAST WITH TIME...FILLING IN OVER THE WEST OVER THE NEXT FEW HOURS...AND THEN OVER THE CENTRAL BY LATER THIS MORNING...AS THE UPPER LEVEL IMPULSE MOVES OVER THE AREA. LATEST OBSERVATIONS AT 400 AM CDT SHOW THAT TEMPERATURES SOUTH AND WEST OF THE MISSOURI RIVER REMAIN ABOVE FREEZING...WHILE NORTH AND EAST...TEMPERATURES ARE IN THE MID TO UPPER 20S. FOLLOWING THE COLD FRONTAL PASSAGE YESTERDAY...COLD AIR ADVECTION ALOFT IS UNDERWAY...WITH A SHALLOW WARM LAYER JUST ABOVE THE SURFACE. PRECIPITATION WILL START AS FREEZING RAIN...WITH SOME SNOW AND SLEET MIXED IN ACROSS THE WEST...BUT AS TEMPERATURES WARM ACROSS THE SOUTHWEST AND SOUTH CENTRAL...A TRANSITION TO RAIN WILL OCCUR. FOR LOCATIONS ACROSS THE NORTH...WHERE TEMPERATURES ARE CURRENTLY SUBFREEZING...PRECIPITATION WILL START AS SNOW...BUT AS TEMPERATURES WARM NEAR THE SURFACE WITH COLDER AIR PRESENT ALOFT...A TRANSITION TO FREEZING RAIN AND THEN TO A MIX OF FREEZING RAIN...SLEET...AND SNOW AFTER MIDNIGHT. EVEN THOUGH THE FORECAST PROCESS HAS LED TO INCREASED MIXED PRECIPITATION (SNOW...SLEET AND FREEZING RAIN) AND DECREASED COVERAGE OF FREEZING RAIN...HAVE DECIDED TO CONTINUE THE FREEZING RAIN ADVISORY AT THIS TIME. WILL CONTINUE TO MONITOR AND MAKE CHANGES IF WARRANTED. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 329 AM CDT SUN APR 7 2013 THE MAIN FORECAST PROBLEM IN THE EXTENDED PERIOD WILL MONDAY THROUGH MONDAY NIGHT...ACTUALLY BEGINNING LATE SUNDAY NIGHT IN THE FAR WEST. WILL LEAN MORE TOWARD A ECMWF/GEM SOLUTION OVER THE GFS/NAM FOR QPF DETAILS. ALTHOUGH THE STRONG UPPER LEVEL SYSTEM IN THE WEST DIVES SOUTH ON MONDAY...THERE IS STILL A PIECE OF UPPER LEVEL ENERGY THAT MAKES IT INTO THE NORTHERN PLAINS. DETERMINISTIC MODELS ARE IN REASONABLE AGREEMENT IN BRINGING THIS INTO THE LOCAL AREA. ALTHOUGH RATHER SIGNIFICANT DIFFERENCES IN THE RESULTING PLACEMENT OF THE QPF AS THE WAVE INTERACT WITH A TIGHTENING BAROCLINIC ZONE ACROSS WESTERN AND CENTRAL NORTH DAKOTA. THE NAM/GFS ARE FARTHER NORTH WITH THE QPF THAN THE GEM/ECMWF...ALTHOUGH THE 00 UTC SUNDAY ECMWF HAS COME A LITTLE FARTHER NORTH THAN PREVIOUS RUNS. LOOKING AT GFS BUFKIT SOUNDINGS...THERE DOES APPEAR TO BE A 3 TO 6 HOUR PERIOD WITH STRONG OMEGA OVER WITHIN THE SNOW GROWTH ZONE IN THE WEST CENTRAL AND SOUTHWEST...WHICH SHOULD YIELD SOME DECENT SNOW AMOUNTS. THIS AREA EXTENDS EAST ACROSS CENTRAL NORTH DAKOTA DURING THE DAY MONDAY BUT STRONG HIGH PRESSURE DROPPING SOUTH FROM CANADA WILL INHIBIT FG FORCING LATER IN THE DAY. THIS SHOULD REDUCE SNOW AMOUNTS AS THE WAVE MOVES EASTWARD INTO CENTRAL AND EASTERN NORTH DAKOTA. A COMBINATION OF HPC SNOW AMOUNTS WITH MODEL QPF YIELDS 3 TO 5 INCHES OF SNOW OVER MUCH OF WEST CENTRAL AND SOUTHWEST NORTH DAKOTA...WITH 2 TO 3 INCHES EXTENDING EAST INTO GRANT AND MORTON COUNTIES. SNOW TOTALS TAPER TO AN INCH OR TWO EAST OF THE MISSOURI RIVER. THE NORTHERN EXTENT OF THE HEAVIER SNOW REMAINS ALONG AND SOUTH OF LAKE SAKAKAWEA...WEST OF THE MISSOURI...THEN ALONG AND SOUTH OF THE I94 CORRIDOR EAST OF THE MISSOURI. ALTHOUGH SIGNIFICANT DIFFERENCES STILL REMAIN...FEEL CONFIDENT ENOUGH THAT A WINTER WEATHER ADVISORY IS WARRANTED OVER THE SOUTHWEST AND WEST CENTRAL. CONFIDENCE WANES AS YOU GO EAST...BUT WILL EXTEND THE ADVISORY EAST TO COVER MOST OF THE AREA WEST OF THE MISSOURI AND SOUTH OF THE LAKE. AT THIS TIME IT APPEARS THAT THERE SHOULD BE A QUICK TRANSITION FROM RAIN TO SNOW AS COLD AIR RUSHES SOUTH LATE SUNDAY NIGHT. HOWEVER...A PERIOD OF MIXED PRECIPITATION CANNOT BE RULED OUT BEFORE THE COLD AIR IS FIRMLY ENTRENCHED OVER THE AREA BY MONDAY MORNING. AS THE CANADIAN HIGH DROPS SOUTH WE SHOULD SEE A NICE ISALLOBARIC COMPONENT MOVE ACROSS THE WEST AND SOUTH CENTRAL ON MONDAY RESULTING IN SUSTAINED WINDS OF 15 TO 20 MPH AND GUST OF 25 TO 30 MPH. ALTHOUGH THERE IS NO LOOSE SNOW...WINDS WILL BE STRONG ENOUGH FOR SOME BLOWING SNOW AS IT FALLS. THUS WILL MAKE THE ADVISORY FOR SNOW AND BLOWING SNOW...LASTING FROM LATE SUNDAY NIGHT THROUGH LATE MONDAY NIGHT. AS THE MAIN UPPER LOW MOVES ONTO THE PLAINS ON TUESDAY...COLD HIGH PRESSURE OVER SASKATCHEWAN INTO NORTH DAKOTA SHOULD KEEP THE NORTHERN EXTEND OF THE SYSTEM RIGHT ALONG THE SOUTH DAKOTA BORDER WITH ANY SIGNIFICANT PRECIPITATION REMAINING SOUTH OF THE STATE. THEN AS THE SYSTEM BEGINS TO EJECT NORTHEAST TUESDAY NIGHT THE PRECIPITATION SHIELD TRIES TO PUSH A BIT FARTHER NORTH AND MAY CLIP THE FAR SOUTH AND SOUTHEAST COUNTIES WITH LIGHT SNOW. AT THIS TIME WE ARE KEEPING HIGH CHANCE POPS ALONG THE SOUTH DAKOTA BORDER...TAPERING TO SLIGHT CHANCE POPS AROUND INTERSTATE 94. THE NORTHERN HALF OF THE CWA IS EXPECTED TO REMAIN DRY TUESDAY AND TUESDAY NIGHT. TEMPERATURES DURING THIS PERIOD...MONDAY THROUGH WEDNESDAY...WILL BE BELOW NORMAL WITH 20S NORTH TO 30S SOUTH. WE DO SEE SOME SLIGHT WARMING BY AROUND THURSDAY AS THE SYSTEM EXITS TO OUR EAST...BUT A PROGRESSIVE NORTHWEST FLOW WILL BRING A SERIES OF UPPER LEVEL WAVES INTO THE AREA LATE IN THE WEEK KEEPING OUR WEATHER UNSETTLED WITH TEMPERATURES NEAR OR BELOW NORMAL. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY MORNING) ISSUED AT 1225 PM CDT SUN APR 7 2013 A WARM FRONT EXTENDED ACROSS SOUTHWEST NORTH DAKOTA. MAIN HAZARD TO AVIATION WILL BE FREEZING RAIN/SLEET AT KJMS THROUGH 21Z. OTHERWISE MVFR FROM KMOT-KJMS. VFR WILL EXTEND FROM KISN-KDIK- KBIS. ANOTHER ROUND OF WINTER WEATHER WILL MOVE INTO WESTERN NORTH DAKOTA SUNDAY NIGHT AND MONDAY. MAIN IMPACTS TO AVIATION WILL BE IFR CONDITIONS SPREADING INTO KDIK AFTER 09Z. MVFR RETURNING TO KISN-KMOT-KBIS-KJMS AFTER 12Z. && .BIS WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 1 AM CDT /MIDNIGHT MDT/ MONDAY TO 1 AM CDT /MIDNIGHT MDT/ TUESDAY FOR NDZ017>020-031>034-040>044. FREEZING RAIN ADVISORY UNTIL 7 PM CDT THIS EVENING FOR NDZ022- 023-037-048-051. && $$ UPDATE...WAA SHORT TERM...LTH LONG TERM...TWH AVIATION...WAA
AREA FORECAST DISCUSSION
NWS TULSA OK
337 PM CDT SUN APR 7 2013 .DISCUSSION... CURRENT SURFACE ANALYSIS SHOWS A SUBTLE PRESSURE TROUGH THAT LIES WEST-EAST ALONG THE KS BORDER. MEANWHILE...MOISTURE CONTINUES TO SLOWLY INCREASE AND SURGE NORTH. AN ISOLATED SUPERCELL DEVELOPED ON THE NORTH SIDE OF THIS FEATURE AND CONTINUES EAST ACROSS KS. THERE IS POTENTIAL LATER THIS AFTERNOON FOR AN ISOLATED STORM TO DEVELOP OVER FAR NW OK/SW-S CNTRL KS AND TRACK EAST TOWARD NE OK. THE MOST RECENT AVAILABLE RUN OF THE HRRR HAS BACKED OFF ON THIS POSSIBILITY BUT IT IS STILL WORTH WATCHING. ANY UPDRAFT THAT CAN SUSTAIN ITSELF WILL LIKELY ROTATE...GIVEN ~50 KTS OF WESTERLY DEEP LAYER SHEAR. THE RIGHT MOVING BUNKERS SUPERCELL VECTOR HAS A MOTION JUST NORTH OF DUE EAST AT 20 KTS. THIS HAS BACKED FROM EARLIER TODAY...MOST LIKELY DUE TO STRENGTHENING WSW FLOW IN ADVANCE OF AN IMPULSE OVER NM PER WV IMAGERY. SO THE BEST POTENTIAL FOR SEVERE STORMS WILL BE NEAR THE KS BORDER AND MAINLY WEST OF HIGHWAY 75 THROUGH THIS EVENING. VERY LARGE HAIL TO BASEBALL SIZE IS CERTAINLY POSSIBLE...AND DUE TO STRENGTHENING 0-1KM SHEAR AN ISOLATED TORNADO OR TWO COULD ACCOMPANY A SUPERCELL IF IT HAPPENED TO PAY US A VISIT THIS EVENING. LOOKS LIKE MORE WIDESPREAD AND MAINLY ELEVATED STORMS WILL GET ALONG AND NORTH OF SURFACE TROUGH TOWARD 06Z AS STRENGTHENING LLJ FOCUSES ISENTROPIC LIFT. THERE IS SOME UNCERTAINTY IN HOW FAR SOUTH TO PUT RAIN CHANCES...AS OUR LOCAL MODEL DEVELOPS STORMS A BIT FARTHER SOUTH. FOR NOW WILL HEDGE AND PUT SLIGHT CHCS DOWN TO NEAR I-40. THE CAP STRENGTHENS ON MONDAY AND THE BOUNDARY TO OUR NORTH CONSOLIDATES WITH A STRENGTHENING WARM FRONT NEAR THE KS/NEB BORDER. CHANCES FOR ANY STORMS TOO LOW TO MENTION IN THE FORECAST. IT IS A HIGHLY CONDITIONAL SETUP (PROBABLY THE BEST OF THE WEEK)...BUT LOW PROB OF OCCURRENCE. THE NEXT BIG CHALLENGE WILL BE LATE TUESDAY INTO WEDNESDAY. THE DATA TODAY HAS NOT REALLY CHANGED MY FORECAST REASONING FROM YESTERDAY MUCH AT ALL. MODEL SOUNDINGS STILL SHOW A DECENT CAP IN THE WARM SECTOR TUESDAY...SO IT WILL BE DIFFICULT TO GET STORMS TO GO WITH THE MAIN UPPER TROUGH STILL WELL WEST AND LACK OF ANY FOCUSING BOUNDARIES IN OUR AREA. IF A STORM DOES GO IN THE WARM SECTOR...IT WOULD LIKELY BE BAD...BUT ODDS ARE PRETTY LOW. THE MOST LIKELY SCENARIO IS FRONTAL FORCING ALONG A SURGING COLD FRONT WILL PROVIDE THE LIFT NEEDED FOR CONVECTION. HOWEVER...SINCE UPPER TROUGH IS COMING OUT WITH A POSITIVE TILT...THE UPPER FLOW WILL BE PARALLEL TO THE FRONT...THUS STORMS THAT DEVELOP WITH THE FRONT WILL TEND TO BE UNDERCUT QUICKLY. THE ECMWF CONTINUES TO SHOW ALMOST ALL QPF ON THE COOL SIDE OF THE FRONT...INDICATIVE OF THIS VERY SCENARIO. I`M NOT SAYING THERE WILL NOT BE SEVERE WEATHER...BUT THE TENDENCY FOR STORMS TO BE UNDERCUT WILL LIMIT THE SEVERE POTENTIAL. POST-FRONTAL RAIN AND STORMS ARE FORECAST TO CONTINUE THRU WEDNESDAY...TAPERING OFF BY THURSDAY MORNING. TEMPS WILL COOL OFF BEHIND THE FRONT...AND WILL REMAIN THAT WAY FOR THE LATTER HALF OF THE WEEK AND INTO THE FIRST PART OF THE WEEKEND. A SUBTLE WAVE WILL PASS THRU THE PLAINS SATURDAY...WITH THE MAIN EFFECT BEING MORE CLOUD COVER. ONCE THAT PASSES...UPPER FLOW TRANSITIONS TO SW AND LEE SIDE LOW PRESSURE DEVELOPS OVER SW KS/SE CO. SOUTHWEST WINDS WILL PREVAIL HERE AND TEMPS WILL REBOUND QUICKLY BY NEXT SUNDAY. LACY && .PRELIMINARY POINT TEMPS/POPS... TUL 61 75 62 75 / 30 10 10 30 FSM 59 74 62 77 / 10 10 10 20 MLC 61 74 63 75 / 10 0 10 20 BVO 60 76 61 74 / 30 10 10 30 FYV 57 71 60 73 / 30 10 10 20 BYV 57 71 59 73 / 30 10 10 20 MKO 59 75 62 74 / 20 10 10 20 MIO 60 74 61 75 / 40 10 10 20 F10 61 74 62 74 / 10 10 10 30 HHW 60 75 63 77 / 0 0 10 20 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...NONE. AR...NONE. && $$ LONG TERM....30
AREA FORECAST DISCUSSION
NWS AMARILLO TX
1233 PM CDT SUN APR 7 2013 .AVIATION... VFR CONDITIONS EXPECTED TO PREVAIL THROUGH THE NEXT 24 HOURS. THE MAIN AVIATION CONCERNS WILL BE THE POTENTIAL FOR STORMS TO DEVELOP NEAR KGUY AND WIND SHIFTS AT ALL TERMINALS. THE THREAT FOR STORMS AT KGUY REMAINS TOO LOW TO MENTION IN PREVAILING AND IS BECOMING INCREASINGLY LESS LIKELY GIVEN THE STRONG CAP ACROSS THE WESTERN OKLAHOMA PANHANDLE. STORMS SHOULD REMAIN WELL AWAY FROM KAMA AND KDHT. THERE AREA COUPLE OF WIND SHIFTS THROUGHOUT THE TAF BUT FOR THE MOST PART WINDS WILL REMAIN LESS THAN 12 KTS. && .PREV DISCUSSION... /ISSUED 1159 AM CDT SUN APR 7 2013/ UPDATE... OVERALL...CHANCE OF STRONG TO SEVERE STORMS DEVELOPING STILL EXISTS FOR THE EASTERN OKLAHOMA AND NORTHEASTERN TEXAS PANHANDLE BUT THESE CHANCES ARE BECOMING LESS LIKELY. STRONG CAPPING IS STILL EXPECTED TO PERSIST UNTIL 3 PM...WEAKEN BETWEEN 3 PM TO 9 PM...AND THEN STRENGTHEN AGAIN AFTER 9 PM. AS SUCH THE ADVERTISED 4 PM TO 9 PM TIME FRAME REMAINS VALID FOR ANY STRONG TO SEVERE STORMS TO FORM. RECENT RUC HRRR AND TTU WRF RUNS HAVE SHOWN A NORTH AND EAST SHIFT IN HIGHER MLCAPE VALUES FAVORING EAST OF A DODGE CITY TO TX/OK STATE BORDER LINE. AS A RESULT THE NE TX AND E OK PANHANDLE RANGES BETWEEN 500-1000 J/KG OF MLCAPE WITH THE HIGHER VALUES IN THE EASTERN EXTREMES OF THE CWA. HOWEVER...SHORT RANGE MODEL SURFACE DEWPOINTS REMAIN A FEW DEGREES TOO HIGH COMPARED TO SURFACE OBSERVATIONS SO CAPE VALUES...SPECIFICALLY SURFACE BASED VALUES...MAY BE A LITTLE OVERDONE. SO STORMS MAY INITIATE OVER THE EXTREME EASTERN TX/OK PANHANDLE THIS AFTERNOON AND EVENING BUT THE LIKELIHOOD OF THESE STORMS BECOMING STRONG TO SEVERE IN OUR FORECAST AREA HAS DECREASED. PREV DISCUSSION... /ISSUED 615 AM CDT SUN APR 7 2013/ AVIATION... FOR THE 12Z TAFS...SFC DRYLINE AND RESIDUAL FRONTAL BOUNDARY ARE EXPECTED TO MOVE INTO ERN SECTIONS OF FCST AREA TODAY. IF ANY THUNDERSTORMS DEVELOP LATE THIS AFTERNOON AND EVENING...THEY SHOULD REMAIN ISOLD AT BEST AND SHOULD NOT AFFECT KDHT OR KAMA. LOW CONFIDENCE AS TO WHETHER OR NOT ANY STORMS WILL AFFECT KGUY SO HAVE OPTED TO LEAVE OUT OF THIS TAF FCST ISSUANCE. OTHERWISE...PERIODS OF MID AND HIGH LEVEL CLOUDS ANTICIPATED THROUGH 12Z MONDAY. ANDRADE PREV DISCUSSION... /ISSUED 331 AM CDT SUN APR 7 2013/ DISCUSSION... AN ACTIVE...ALBEIT MOSTLY DRY...WEATHER PATTERN IS ON TAP FOR THE REGION FOR THE NEXT WEEK. TODAY AND TONIGHT...THE FOCUS IS ON THE POTENTIAL FOR SEVERE THUNDERSTORMS LATE THIS AFTERNOON INTO THIS EVENING OVER THE OKLAHOMA AND NORTHERN AND EASTERN TEXAS PANHANDLES. THE BIGGEST QUESTION IS IF STORMS WILL EVEN DEVELOP. SURFACE AND LOW LEVEL CONFLUENCE ALONG A WARM FRONT AND DRYLINE WILL NEED TO BE JUXTAPOSED WITH MEAGER MID AND UPPER LEVEL SUPPORT AS A SMALL SHORTWAVE TROUGH SLIDES E OVER THE OK PANHANDLE LATE TODAY. THIS IS FAR FROM A SURE THING AS MANY OF THE SHORTER RANGE MODELS SHOW THE CENTER OF THE SURFACE LOW IN THE SW TX PANHANDLE...WITH THE FRONT AND DRYLINE FEATURES WELL SOUTH OF THE EXPECTED TRACK OF THE MID AN UPPER LEVEL TROUGH. IF THIS IS THE CASE...AM NOT CONVINCED THAT THE LOW LEVEL CONFLUENCE IS ENOUGH TO OVERCOME THE STRONG CAP. ADDITIONALLY...STILL CONCERNED THAT MODELS ARE TOO AGGRESSIVE WITH LOW LEVEL MOISTURE RETURN. AT 08Z...UPSTREAM OBS SHOW DEWPOINT TEMPERATURES GENERALLY IN THE40S AND 50S...BUT THE NAM AND OTHER HIGH RESOLUTION MODELS SHOW A SURGE OF 60 OR HIGHER DEW POINT TEMPERATURES BY 21Z. CAN/T SEE HOW WE WOULD HAVE THAT MUCH MOISTURE ADVECTION IN SUCH A SHORT PERIOD OF TIME. HOWEVER IF STORMS CAN DEVELOP...THERE IS A RISK THAT THEY WILL BECOME SEVERE. AS FOR THE SEVERE THREATS... HAIL SHOULD BE THE MAIN THREAT. MODEL SOUNDINGS SHOW ML CAPE VALUES NEAR OR ABOVE 1000 J/KG. MUCH OF THAT IS IN THE HAIL GROWTH REGION. IN ADDITION...BULK SHEAR VALUES...WHILE NOT AS HIGH AS WE/VE SEEN WITH SOME OF THE SEVERE EVENTS LATELY...SHOULD STILL BE NEAR 40 KT...PLENTY ENOUGH TO SUPPORT SUSTAINED UPDRAFTS. WIND...FOR A CHANGE THE WIND THREAT...WHILE NOT ZERO...IS LOWER THAN THE HAIL THREAT. THE LOW AND MID LEVEL JETS SHOULD BE WELL EAST OF THE REGION. THUS ANY STRONG WINDS WOULD EITHER HAVE TO BE MIXED DOWN FROM THE UPPER LEVELS...OR WOULD HAVE TO SEE A DOWNBURST ENHANCED BY PRECIPITATION LOADING. TORNADO...THE TORNADO THREAT IS MINIMAL. THE MAIN REASONS IT IS SO LOW IS MINIMAL HELICITY VALUES...HIGH LCL HEIGHTS...AND MODEST BULK SHEAR VALUES...AND MOSTLY SPEED SHEAR AT THAT. HOWEVER...IT SHOULD BE NOTED THAT THERE COULD BE SOME ENHANCED DIRECTIONAL SHEAR ALONG THE BOUNDARIES BUT GIVEN THE WEST TO EAST STORM MOTIONS...DO NOT EXPECT STORMS TO REMAIN CONNECTED TO EITHER THE FRONT OR DRY LINE FOR VERY LONG. FLOODING...FLOODING THREAT IS ALSO MINIMAL. THOUGH STORM MOTIONS WILL BE RELATIVELY LOW...GENERALLY 15KT OR LESS...PRECIPITABLE WATER VALUES ARE ONLY EXPECTED TO BE SLIGHTLY ABOVE NORMAL. IN ADDITION...STORM MOTIONS AND BOUNDARY POSITIONS ARE NOT FAVORABLE FOR TRAINING...AND GIVEN LIMITED COVERAGE DO NOT EXPECT MULTIPLE STORMS TO MOVE OVER THE SAME LOCATIONS. MONDAY...STILL LOOKING AT A WINDY DAY MAINLY DU TO INCREASING MID AND UPPER LEVEL HEIGHT GRADIENTS AS THE MAIN TROUGH SLIDES INTO THE FOUR CORNERS REGION. A COMBINATION OF A THICK CIRRUS DECK LIMITING MIXING...AND A LATE DEVELOPMENT OF THE TIGHTEST HEIGHT AND PRESSURE GRADIENTS WILL MEAN THAT WHILE IT WILL BE WINDY...WE WILL LIKELY STAY BELOW WIND ADVISORY CRITERIA. TUESDAY...THE MAIN STORY ON THIS DAY WILL BE THE COLD FRONT. THE BIGGEST SOURCE OF UNCERTAINTY IS THE TIMING OF THE FRONT. WITH THE 00Z RUNS...THERE WAS RATHER GOOD AGREEMENT ON THE TIMING OF THE FRONT...ARRIVING IN AMA BETWEEN 21 AND 00Z...BUT RATHER POOR RUN TO RUN CONSISTENCY...AS THIS IS A BIT FASTER THAN THE 12Z RUNS. SOME THINGS OF NOTE WITH THIS FRONT...FIRST...MODELS SHOW LARGE PRESSURE RISES...ALMOST UNBELIEVABLY LARGE PRESSURE RISES...BEHIND THE FRONT. THIS SHOULD LEAD STRONG POST FRONTAL WINDS...POSSIBLY NEAR WIND ADVISORY. SECOND...THOUGH THE MAIN MID AND UPPER LEVEL TROUGH IS QUICKLY LIFTING NE AT THIS TIME...LEAVING THE PANHANDLES IN A PRIME LOCATION FOR THE DRY SLOT...SOME MODELS...MOST NOTABLY THE ECMWF...CONTINUE TO SHOW PRECIPITATION BEHIND THE FRONT. IF ANY PRECIP CAN DEVELOP...EXPECT THAT IT WILL BE THE RESULT OF RATHER SHALLOW ISENTROPIC LIFT. THUS...EXPECT ONLY VERY LIGHT...IF ANY...PRECIP. WEDNESDAY THROUGH SUNDAY...REGION SHOULD SEE A RETURN TO A MORE ZONAL FLOW PATTERN. FIRST A LEE SIDE SURFACE TROUGH IS EXPECTED TO DEVELOP BY THURSDAY BRINGING A QUICK WARMING TREND. THERE COULD BE A FEW EMBEDDED UPPER LEVEL SHORTWAVE TROUGHS TOWARDS THE END OF THE WEEK...BUT UNCERTAINTY IN TIMING AND TRACK IS VERY HIGH AT THIS TIME. JOHNSON FIRE WEATHER... DESPITE RELATIVE HUMIDITY VALUES NEAR OR BELOW 15 PERCENT...DO NOT EXPECT ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS DUE TO RELATIVELY LIGHT WINDS. ON MONDAY...CRITICAL FIRE WEATHER CONDITIONS ARE POSSIBLE OVER THE WESTERN TEXAS PANHANDLE AND ELEVATED FIRE WEATHER CONDITIONS ARE POSSIBLE ACROSS MUCH OF THE REST OF THE PANHANDLES DUE TO SOUTHWESTERLY WINDS OF 15 TO 25 MPH...AND RELATIVE HUMIDITY VALUES BETWEEN 10 AND 20 PERCENT. A COLD FRONT IS EXPECTED ON TUESDAY...BRINGING AN ABRUPT SHIFT TO STRONG NORTHERLY WINDS. DEPENDING ON HOW LATE IN THE DAY IT ARRIVES...ELEVATED TO NEAR CRITICAL FIRE WEATHER CONDITIONS MAY BE POSSIBLE ACROSS THE SOUTHERN TEXAS PANHANDLE. JOHNSON && .AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. && $$ 14/09
AREA FORECAST DISCUSSION
NWS AMARILLO TX
1159 AM CDT SUN APR 7 2013 .UPDATE... OVERALL...CHANCE OF STRONG TO SEVERE STORMS DEVELOPING STILL EXISTS FOR THE EASTERN OKLAHOMA AND NORTHEASTERN TEXAS PANHANDLE BUT THESE CHANCES ARE BECOMING LESS LIKELY. STRONG CAPPING IS STILL EXPECTED TO PERSIST UNTIL 3 PM...WEAKEN BETWEEN 3 PM TO 9 PM...AND THEN STRENGTHEN AGAIN AFTER 9 PM. AS SUCH THE ADVERTISED 4 PM TO 9 PM TIME FRAME REMAINS VALID FOR ANY STRONG TO SEVERE STORMS TO FORM. RECENT RUC HRRR AND TTU WRF RUNS HAVE SHOWN A NORTH AND EAST SHIFT IN HIGHER MLCAPE VALUES FAVORING EAST OF A DODGE CITY TO TX/OK STATE BORDER LINE. AS A RESULT THE NE TX AND E OK PANHANDLE RANGES BETWEEN 500-1000 J/KG OF MLCAPE WITH THE HIGHER VALUES IN THE EASTERN EXTREMES OF THE CWA. HOWEVER...SHORT RANGE MODEL SURFACE DEWPOINTS REMAIN A FEW DEGREES TOO HIGH COMPARED TO SURFACE OBSERVATIONS SO CAPE VALUES...SPECIFICALLY SURFACE BASED VALUES...MAY BE A LITTLE OVERDONE. SO STORMS MAY INITIATE OVER THE EXTREME EASTERN TX/OK PANHANDLE THIS AFTERNOON AND EVENING BUT THE LIKELIHOOD OF THESE STORMS BECOMING STRONG TO SEVERE IN OUR FORECAST AREA HAS DECREASED. && .PREV DISCUSSION... /ISSUED 615 AM CDT SUN APR 7 2013/ AVIATION... FOR THE 12Z TAFS...SFC DRYLINE AND RESIDUAL FRONTAL BOUNDARY ARE EXPECTED TO MOVE INTO ERN SECTIONS OF FCST AREA TODAY. IF ANY THUNDERSTORMS DEVELOP LATE THIS AFTERNOON AND EVENING...THEY SHOULD REMAIN ISOLD AT BEST AND SHOULD NOT AFFECT KDHT OR KAMA. LOW CONFIDENCE AS TO WHETHER OR NOT ANY STORMS WILL AFFECT KGUY SO HAVE OPTED TO LEAVE OUT OF THIS TAF FCST ISSUANCE. OTHERWISE...PERIODS OF MID AND HIGH LEVEL CLOUDS ANTICIPATED THROUGH 12Z MONDAY. ANDRADE PREV DISCUSSION... /ISSUED 331 AM CDT SUN APR 7 2013/ DISCUSSION... AN ACTIVE...ALBEIT MOSTLY DRY...WEATHER PATTERN IS ON TAP FOR THE REGION FOR THE NEXT WEEK. TODAY AND TONIGHT...THE FOCUS IS ON THE POTENTIAL FOR SEVERE THUNDERSTORMS LATE THIS AFTERNOON INTO THIS EVENING OVER THE OKLAHOMA AND NORTHERN AND EASTERN TEXAS PANHANDLES. THE BIGGEST QUESTION IS IF STORMS WILL EVEN DEVELOP. SURFACE AND LOW LEVEL CONFLUENCE ALONG A WARM FRONT AND DRYLINE WILL NEED TO BE JUXTAPOSED WITH MEAGER MID AND UPPER LEVEL SUPPORT AS A SMALL SHORTWAVE TROUGH SLIDES E OVER THE OK PANHANDLE LATE TODAY. THIS IS FAR FROM A SURE THING AS MANY OF THE SHORTER RANGE MODELS SHOW THE CENTER OF THE SURFACE LOW IN THE SW TX PANHANDLE...WITH THE FRONT AND DRYLINE FEATURES WELL SOUTH OF THE EXPECTED TRACK OF THE MID AN UPPER LEVEL TROUGH. IF THIS IS THE CASE...AM NOT CONVINCED THAT THE LOW LEVEL CONFLUENCE IS ENOUGH TO OVERCOME THE STRONG CAP. ADDITIONALLY...STILL CONCERNED THAT MODELS ARE TOO AGGRESSIVE WITH LOW LEVEL MOISTURE RETURN. AT 08Z...UPSTREAM OBS SHOW DEWPOINT TEMPERATURES GENERALLY IN THE40S AND 50S...BUT THE NAM AND OTHER HIGH RESOLUTION MODELS SHOW A SURGE OF 60 OR HIGHER DEW POINT TEMPERATURES BY 21Z. CAN/T SEE HOW WE WOULD HAVE THAT MUCH MOISTURE ADVECTION IN SUCH A SHORT PERIOD OF TIME. HOWEVER IF STORMS CAN DEVELOP...THERE IS A RISK THAT THEY WILL BECOME SEVERE. AS FOR THE SEVERE THREATS... HAIL SHOULD BE THE MAIN THREAT. MODEL SOUNDINGS SHOW ML CAPE VALUES NEAR OR ABOVE 1000 J/KG. MUCH OF THAT IS IN THE HAIL GROWTH REGION. IN ADDITION...BULK SHEAR VALUES...WHILE NOT AS HIGH AS WE/VE SEEN WITH SOME OF THE SEVERE EVENTS LATELY...SHOULD STILL BE NEAR 40 KT...PLENTY ENOUGH TO SUPPORT SUSTAINED UPDRAFTS. WIND...FOR A CHANGE THE WIND THREAT...WHILE NOT ZERO...IS LOWER THAN THE HAIL THREAT. THE LOW AND MID LEVEL JETS SHOULD BE WELL EAST OF THE REGION. THUS ANY STRONG WINDS WOULD EITHER HAVE TO BE MIXED DOWN FROM THE UPPER LEVELS...OR WOULD HAVE TO SEE A DOWNBURST ENHANCED BY PRECIPITATION LOADING. TORNADO...THE TORNADO THREAT IS MINIMAL. THE MAIN REASONS IT IS SO LOW IS MINIMAL HELICITY VALUES...HIGH LCL HEIGHTS...AND MODEST BULK SHEAR VALUES...AND MOSTLY SPEED SHEAR AT THAT. HOWEVER...IT SHOULD BE NOTED THAT THERE COULD BE SOME ENHANCED DIRECTIONAL SHEAR ALONG THE BOUNDARIES BUT GIVEN THE WEST TO EAST STORM MOTIONS...DO NOT EXPECT STORMS TO REMAIN CONNECTED TO EITHER THE FRONT OR DRY LINE FOR VERY LONG. FLOODING...FLOODING THREAT IS ALSO MINIMAL. THOUGH STORM MOTIONS WILL BE RELATIVELY LOW...GENERALLY 15KT OR LESS...PRECIPITABLE WATER VALUES ARE ONLY EXPECTED TO BE SLIGHTLY ABOVE NORMAL. IN ADDITION...STORM MOTIONS AND BOUNDARY POSITIONS ARE NOT FAVORABLE FOR TRAINING...AND GIVEN LIMITED COVERAGE DO NOT EXPECT MULTIPLE STORMS TO MOVE OVER THE SAME LOCATIONS. MONDAY...STILL LOOKING AT A WINDY DAY MAINLY DU TO INCREASING MID AND UPPER LEVEL HEIGHT GRADIENTS AS THE MAIN TROUGH SLIDES INTO THE FOUR CORNERS REGION. A COMBINATION OF A THICK CIRRUS DECK LIMITING MIXING...AND A LATE DEVELOPMENT OF THE TIGHTEST HEIGHT AND PRESSURE GRADIENTS WILL MEAN THAT WHILE IT WILL BE WINDY...WE WILL LIKELY STAY BELOW WIND ADVISORY CRITERIA. TUESDAY...THE MAIN STORY ON THIS DAY WILL BE THE COLD FRONT. THE BIGGEST SOURCE OF UNCERTAINTY IS THE TIMING OF THE FRONT. WITH THE 00Z RUNS...THERE WAS RATHER GOOD AGREEMENT ON THE TIMING OF THE FRONT...ARRIVING IN AMA BETWEEN 21 AND 00Z...BUT RATHER POOR RUN TO RUN CONSISTENCY...AS THIS IS A BIT FASTER THAN THE 12Z RUNS. SOME THINGS OF NOTE WITH THIS FRONT...FIRST...MODELS SHOW LARGE PRESSURE RISES...ALMOST UNBELIEVABLY LARGE PRESSURE RISES...BEHIND THE FRONT. THIS SHOULD LEAD STRONG POST FRONTAL WINDS...POSSIBLY NEAR WIND ADVISORY. SECOND...THOUGH THE MAIN MID AND UPPER LEVEL TROUGH IS QUICKLY LIFTING NE AT THIS TIME...LEAVING THE PANHANDLES IN A PRIME LOCATION FOR THE DRY SLOT...SOME MODELS...MOST NOTABLY THE ECMWF...CONTINUE TO SHOW PRECIPITATION BEHIND THE FRONT. IF ANY PRECIP CAN DEVELOP...EXPECT THAT IT WILL BE THE RESULT OF RATHER SHALLOW ISENTROPIC LIFT. THUS...EXPECT ONLY VERY LIGHT...IF ANY...PRECIP. WEDNESDAY THROUGH SUNDAY...REGION SHOULD SEE A RETURN TO A MORE ZONAL FLOW PATTERN. FIRST A LEE SIDE SURFACE TROUGH IS EXPECTED TO DEVELOP BY THURSDAY BRINGING A QUICK WARMING TREND. THERE COULD BE A FEW EMBEDDED UPPER LEVEL SHORTWAVE TROUGHS TOWARDS THE END OF THE WEEK...BUT UNCERTAINTY IN TIMING AND TRACK IS VERY HIGH AT THIS TIME. JOHNSON FIRE WEATHER... DESPITE RELATIVE HUMIDITY VALUES NEAR OR BELOW 15 PERCENT...DO NOT EXPECT ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS DUE TO RELATIVELY LIGHT WINDS. ON MONDAY...CRITICAL FIRE WEATHER CONDITIONS ARE POSSIBLE OVER THE WESTERN TEXAS PANHANDLE AND ELEVATED FIRE WEATHER CONDITIONS ARE POSSIBLE ACROSS MUCH OF THE REST OF THE PANHANDLES DUE TO SOUTHWESTERLY WINDS OF 15 TO 25 MPH...AND RELATIVE HUMIDITY VALUES BETWEEN 10 AND 20 PERCENT. A COLD FRONT IS EXPECTED ON TUESDAY...BRINGING AN ABRUPT SHIFT TO STRONG NORTHERLY WINDS. DEPENDING ON HOW LATE IN THE DAY IT ARRIVES...ELEVATED TO NEAR CRITICAL FIRE WEATHER CONDITIONS MAY BE POSSIBLE ACROSS THE SOUTHERN TEXAS PANHANDLE. JOHNSON && .AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. && $$ 14/09
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1226 PM CDT SUN APR 7 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 342 AM CDT SUN APR 7 2013 CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED UPPER TROUGHING APPROACHING THE PACIFIC NORTHWEST...WEAK RIDGING OVER THE NORTHERN U.S. ROCKIES INTO THE DAKOTAS...AND A SHORTWAVE TROUGH OVER EASTERN WISCONSIN. ALSO OF NOTE ON WATER VAPOR WERE A PAIR OF SHORTWAVES MOVING THROUGH THE WEAK RIDGING...ONE IN SOUTH CENTRAL WYOMING AND THE OTHER IN NORTHWEST COLORADO. THE FORECAST AREA LIES IN SUBSIDENCE IN THE WAKE OF THE EASTERN WISCONSIN SHORTWAVE TROUGH...SEEN AS AN INVERSION BETWEEN 775 AND 850MB ON THE 00Z MPX SOUNDING. THIS INVERSION WAS ALSO SATURATED... REFLECTED TOO BY PLENTY OF STRATUS CLOUDS ON 11-3.9UM IMAGERY FROM THE EASTERN DAKOTAS INTO THE FORECAST AREA. COOLER AIR HAS BEEN FILTERING IN BEHIND THE SHORTWAVE AS WELL WITH 850MB TEMPS NOW DOWN TO +2 TO -3C ACROSS THE FORECAST AREA PER RAP ANALYSIS...COLDEST OVER CENTRAL WISCONSIN. AT THE SURFACE...HIGH PRESSURE WAS SEEN DROPPING SOUTH INTO WESTERN MINNESOTA...IN THE WAKE OF LOW PRESSURE OVER NORTHERN LAKE MICHIGAN AND ITS COLD FRONT WHICH EXTENDS SOUTHWEST TO KANSAS CITY. A PATTERN CHANGE IS FORECAST TO OCCUR ALOFT DURING THE NEXT 24 HOURS AS THE UPPER TROUGH SEEN OFF THE PACIFIC NORTHWEST SHARPLY DIGS SOUTH INTO CALIFORNIA AND NEVADA. IN RESPONSE...RIDGING WILL BUILD DOWNSTREAM...ADJUSTING THE UPPER LEVEL FLOW TO SOUTHWESTERLY OVER THE FORECAST AREA. THIS MEANS THAT THE RECENT LOW LEVEL COLD ADVECTION WILL COME TO AN END SHORTLY...WITH WARM ADVECTION PROGGED TO BEGIN BETWEEN 12-18Z TODAY AND CONTINUE THROUGH TONIGHT. IN ADDITION...MODELS HAVE BEEN CONSISTENT IN SHOWING THE PAIR OF SHORTWAVES SEEN IN WYOMING AND COLORADO TO AFFECT THE FORECAST AREA LATE TONIGHT AS THEY RIDE THROUGH THE SOUTHWEST FLOW. THE FIRST TWO ISSUES FOR THE SHORT TERM PERIOD ARE THE CLOUDS AND HIGH TEMPERATURES TODAY. THE PRESENT STRATUS DECK DOES HAVE SOME HOLES IN IT ON ITS SOUTHERN SIDE. THESE HOLES SHOULD EXPAND THROUGH THE MORNING AS DIURNAL MIXING COMMENCES. 07.00Z NAM LOW LEVEL RH FIELDS...WHICH GENERALLY TEND PESSIMISTIC...ALSO SUGGEST THAT THE STRATUS DECK WILL MOSTLY MIX OUT BY 18Z SOUTH OF US HIGHWAY 10. LATER IN THE AFTERNOON...SAY 21Z AND AFTER...MID AND HIGH CLOUDS CURRENTLY SPREADING INTO THE PLAINS STATES ARE PROGGED TO MOVE INTO THE FORECAST AREA. THUS WE SHOULD SEE AT LEAST A FEW HOURS OF MOSTLY SUNNY SKIES TODAY. WITH 850MB TEMPS CLIMBING TO 0C NORTH AND 6C SOUTH BY 18Z...ANTICIPATING THAT MOST LOCATIONS MINUS NORTH OF HIGHWAY 10 WHERE MORE CLOUDS AND SNOW EXIST WILL CLIMB INTO THE 50S. WARMEST TEMPERATURES...APPROACHING 60...ARE EXPECTED IN THE FAR SOUTH. THE NEXT ISSUE FOR THE SHORT TERM PERIOD IS THE POTENTIAL FOR PRECIPITATION VERY LATE THIS AFTERNOON INTO TONIGHT...DUE TO THE WARM ADVECTION PATTERN AND THE APPROACH OF THE PAIR OF SHORTWAVES. THE 07.00Z GFS/06.12Z ECMWF ALREADY SHOW HINTS OF WARM ADVECTION / ISENTROPICALLY INDUCED PRECIPITATION AFFECTING FAR WESTERN PORTIONS OF THE FORECAST AREA BETWEEN 21-00Z TODAY. THINKING THIS MIGHT BE A BIT FAST...WITH THE 07.00Z NAM/REGIONAL CANADIAN/HIRES-ARW AND 07.03Z SREF ALL SLOWER. THUS...PLAN ON KEEPING CONDITIONS DRY TIL 00Z. AS WE HEAD THROUGH TONIGHT...THERE IS A STRONG CONSENSUS AMONGST ALL MODEL GUIDANCE OF A PRECIPITATION SPLIT. THE NORTHERN AREA TRACKS FROM NORTHWEST IA/SOUTHERN MN INTO NORTHWEST WISCONSIN. THE SOUTHERN AREA TRACKS FROM NORTHERN MISSOURI INTO SOUTHEAST IA AND NORTHWEST IL. THIS SPLIT APPEARS TO BE A RESULT OF HOW THE PAIR OF SHORTWAVES APPROACHING THE FORECAST AREA LATE TONIGHT INTERACT WITH THE ISENTROPIC LIFT PATTERN IN PLACE. 850MB MOISTURE TRANSPORT FIELDS SHOW THE SPLIT INTERACTION WITH THE ISENTROPIC LIFT PATTERN NICELY. IN ADDITION...THERE ARE OTHER SUPPORTING FEATURES. FOR EXAMPLE...THE NORTHERN AREA BECOMES INFLUENECED BY A DEVELOPING AND STRENGTHENING UPPER JET STREAK OVER UPPER MICHIGAN...PLACING IT IN THE FAVORABLE RIGHT ENTRANCE REGION. MEANWHILE...THE SOUTHERN AREA HAS A STRONG LOW TO MID- LEVEL FRONTOGENESIS FEATURE ALONG THE PRESENT COLD FRONT NEAR I-70...WHICH FOR ALL INTENSIVE PUPROSES TURNS INTO A STATIONARY BOUNDARY. SO FOR THE FORECAST...THIS WELL AGREED UPON SPLIT PRECIPITATION SCENARIO POSES A PROBLEM FROM WHAT WE HAD GOING PREVIOUSLY. HAVE ADJUSTED PRECIPITATION CHANCES AND QPF QUITE A BIT LOWER SOUTH OF I-90...SINCE THIS AREA WILL BE ON THE SUBSIDENT SIDE OF THE F-GEN CIRCULATION. NOTE THAT MODELS LIKE THE 07.00Z GFS/REGIONAL CANADIAN EVEN SUGGEST THAT SOME LOCATIONS ACROSS NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN COULD END UP DRY. REGARDING PRECIPITATION TYPE...ALL OF IT SHOULD FALL AS RAIN WITH WET-BULB ZERO HEIGHTS PROGGED WELL ABOVE 2000 FT. THE PREVIOUS FORECAST INTRODUCED A CHANCE FOR THUNDER AND THIS STILL LOOKS REASONABLE AFTER MIDNIGHT...WITH POTENTIAL FOR A FEW HUNDERED J/KG OF SKINNY CAPE LIFTED FROM 850MB. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 342 AM CDT SUN APR 7 2013 OVERALL MUCH OF THE LONG TERM PERIOD LOOKS ACTIVE...THANKS TO THAT TROUGH DIGGING INTO CALIFORNIA AND NEVADA TONIGHT. QUITE A FEW DETAILS TO NOTE. ON MONDAY...THE PAIR OF SHORTWAVES ARE PROGGED TO SHIFT EAST INTO MICHIGAN DURING THE AFTERNOON...TAKING THE BULK OF THE SPLIT PRECIPITATION TONIGHT WITH THEM. HOWEVER...THE STORY DOES NOT END THERE. THE FOCUS TURNS TO THE FRONTAL BOUNDARY NEAR I-70...WHICH BY ALL MODELS IS SUGGESTED TO LIFT NORTH INTO CENTRAL AND PERHAPS NORTHERN IA DURING THE AFTERNOON. THE LIFTING NORTH IS A RESULT OF THE UPPER TROUGHING DEEPENING AND DIGGING INTO THE FOUR CORNERS REGION...ENHANCING THE WARM ADVECTION DOWNSTREAM. THE 07.00Z REGIONAL CANADIAN AND NAM SUGGEST THERE IS POTENTIAL FOR SURFACE BASED CONVECTION TO FIRE ON THIS FRONT. THE 07.00Z GFS...ON THE OTHER HAND...HAS A FARTHER SOUTH FRONT AND KEEPS THINGS MORE CAPPED. HOWEVER...ALL THREE MODELS INCLUDING THE 06.12Z ECMWF DEPICT POTENTIAL FOR FRONTOGENETICALY INDUCED PRECIPITATION NORTH OF THE FRONTAL BOUNDARY. THUS...A NEED CONTINUES FOR CHANCES OF SHOWERS ALONG WITH THE THUNDERSTORM MENTION IN THE EVENT THE REGIONAL CANADIAN/NAM PAN OUT. IF THE REGIONAL CANADIAN/NAM PAN OUT... CERTAINLY COULD NOT RULE OUT SOME SEVERE POTENTIAL GIVEN 0-6 KM SHEAR UPWARS OF 45-50 KT. HOWEVER...IT SEEMS LIKE THE BETTER INSTABILITY IS WEST OF THE FORECAST AREA...THUS KEEPING THE BULK OF THE SEVERE POTENTIAL TO THE WEST. SPC DAY 2 SEVERE PROBABILITIES DEPICT THIS AS WELL. DEFINITELY SOMETHING TO KEEP AN EYE ON....THOUGH. TEMPERATURE FORECAST IS TRICKY AS IT DEPENDS ON THE FRONTAL POSITION. A NAM/REGIONAL CANADIAN OR EVEN ECMWF SOLUTION WOULD ALLOW FOR HIGHS IN THE 60S TO POSSIBLY 70 ALONG/SOUTH OF I-90. THE GFS IS A LITTLE COOLER BUT STILL HAS HIGHS IN THE 60S SOUTH OF I-90. RAISED HIGHS 5 DEGREES OR SO TO COME BETTER IN AGREEMENT WITH ALL 07.00Z GUIDANCE...BUT THEY MAY NEED TO BE RAISED MORE... ESPECIALLY IF MORE SUN OCCURS IN THE AFTERNOON. THINGS GET MORE INTERESTING HEADING INTO THE MONDAY NIGHT THROUGH THURSDAY TIME PERIOD. DURING THIS PERIOD...ALL MODELS HAVE THE DEEP UPPER TROUGH OVER THE FOUR CORNERS SLOWLY LIFTING TO THE EAST-NORTHEAST. MEANWHILE...AT THE SAME TIME THERE IS A DEEP UPPER TROUGH HANGING AROUND THE HUDSON BAY INTO NORTHERN ONTARIO AREA... HELPING TO HOLD AN UPPER JET STREAK IN PLACE OVER THE NORTHERN GREAT LAKES. THIS MEANS THE FORECAST AREA IS GOING TO BE PLACED IN THE FAVORABLE RIGHT ENTRANCE REGION UNTIL THE UPPER TROUGH MOVES IN. MONDAY NIGHT FOR THE MOST PART LOOKS QUIET...WITH ANY SHOWERS AND POSSIBLE THUNDERSTORMS IN THE EVENING DISSIPATING WITH LOSS OF DAYTIME HEATING. THE FRONTAL BOUNDARY...IF IT IS NEARBY...LOOKS TO SLOWLY DROP SOUTH MONDAY NIGHT FORCED BY THAT DEEP UPPER TROUGH TO OUR NORTH. IT APPEARS THERE MAY BE A MASS OF LOW LEVEL STRATUS THAT MOVES IN BEHIND THE FRONT...AND WITH LOW LEVEL FRONTOGENESIS BEHIND THE FRONT WE COULD DEAL WITH SOME LIGHT RAIN OR DRIZZLE. PRECIPITATION CHANCES DEFINITELY GO ON THE INCREASE FROM SOUTHWEST TO NORTHEAST THROUGH THE DAY TUESDAY AND INTO TUESDAY NIGHT...IN RESPONSE TO ISENTROPIC LIFT STRENGTHENING DOWNSTREAM OF THE UPPER TROUGH PUSHING TO THE EAST-NORTHEAST. SOME CONCERN FOR SOME HEAVIER RAIN TUESDAY NIGHT...ESPECIALLY ACROSS THE SOUTH...AS PRECIPITABLE WATER VALUES INCREASE OVER 1 INCH AND SOME WEAK ELEVATED INSTABILITY MOVES IN FOR THUNDERSTORMS. RAISED BOTH PRECIPITATION CHANCES AND QPF FOR TUESDAY AND ESPECIALLY TUESDAY NIGHT GIVEN THE STRONG SIGNAL AMONGST THE 07.00Z ECMWF/GFS/CANADIAN MODELS. FROM WEDNESDAY INTO THURSDAY...THE CORE OF THE UPPER TROUGH IS PROGGED TO SLOWLY APPROACH THE FORECAST AREA. AS THIS OCCURS...THE FORECAST AREA EVENTUALLY ENDS UP ON THE NORTHWEST / COLD SIDE OF A SURFACE LOW TRACKING TO OUR SOUTH...PLACING THE AREA INTO THE TROWAL AND COLD CONVEYOR BELT REGION. GIVEN THE GOOD MODEL AGREEMENT AGAIN...RAISED PRECIPITATION CHANCES UP DURING THIS PERIOD. IN ADDITION...WILL HAVE TO WATCH FOR SOME SNOW ACCUMULATIONS COME WEDNESDAY NIGHT AND THURSDAY AS 850MB TEMPS DROP TO -4 TO -8C BY 12Z THURSDAY. IT SHOULD BE NOTED THAT THE 07.00Z NAM IS AN OUTLIER SOLUTION TO THE ABOVE SCENARIO...PARTICULARLY FOR TUESDAY THROUGH WEDNESDAY...SINCE IT EJECTS THE CORE OF THE SOUTHWESTERN TROUGH MUCH QUICKER AND LIFTS IT FARTHER NORTH. THE NAM WAS DISCOUNTED GIVEN GOOD MODEL AGREEMENT BETWEEN ALL OTHER MODELS. THE 07.03Z SREF LOOKS LIKE A COMPROMISE BETWEEN THE NAM AND GFS...BUT THE SREF IS NAM-BIASED DUE TO AN OVERWHELMING AMOUNT OF NAM MEMBERS. THUS...THE SREF WAS DISCOUNTED AS WELL. LOOKING FARTHER AHEAD...GOOD MODEL AGREEMENT EXISTS AMONGST THE 07.00Z ECMWF/GFS/CANADIAN ON BRINGING COLD CANADIAN HIGH PRESSURE INTO THE AREA THURSDAY NIGHT THROUGH FRIDAY NIGHT. THIS SHOULD HELP DRY THINGS OUT. LEFT A CONSENUS 20 PERCENT CHANCE OF PRECIPITATION IN THURSDAY NIGHT...BUT THIS PERIOD MAY EVENTUALLY END UP DRY. WILL NEED TO WATCH SOME OF THE LOW TEMPERATURES TOO FOR BOTH THURSDAY NIGHT AND FRIDAY NIGHT...DEPENDING ON HOW MUCH FRESH SNOW WE PICK UP AND FOR FRIDAY NIGHT HOW MUCH IS STILL ON THE GROUND. A WARM ADVECTION PATTERN SETS UP FOR SATURDAY AHEAD OF NEW TROUGHING DROPPING INTO THE NORTHERN ROCKIES. FOLLOWED THE CONSENSUS HERE OF BRINGING SOME 20-30 PERCENT CHANCES OF PRECIPITATION ACROSS THE AREA ON SATURDAY. NEED TO MAINTAIN A RAIN/SNOW MIX BECAUSE 850MB TEMPS ARE STILL SLOW TO WARM...ESPECIALLY IN THE ECMWF WHERE IT KEEPS THEM BELOW 0C THROUGH 00Z SUNDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1226 PM CDT SUN APR 7 2013 MVFR STRATUS IN PLACE ACROSS THE REGION GOING INTO THIS AFTERNOON. RAP/NAM BUFKIT SOUNDINGS INSIST THAT THIS STRATUS WILL DISPERSE FROM SOUTH TO NORTH ACROSS THE AREA. LATEST VIS SATELLITE LOOP...IN FACT...STARTING TO SHOW THIS TREND. BASED ON THIS...HAVE KRST AND KLSE SCATTERING OUT IN THE 22-23Z TIME FRAME. THIS CLEARING WILL BE SHORT-LIVED HOWEVER DUE TO VFR MID-CLOUD SPREADING NORTHEAST OUT OF THE PLAINS AHEAD OF LOW PRESSURE DEVELOPING OVER THE INTERMOUNTAIN WEST. LOOK FOR THE LOW TO SLOWLY LIFT OUT OF THE INTERMOUNTAIN WEST INTO THE PLAINS TONIGHT INTO MONDAY. THIS WILL LIFT A WARM FRONT NORTHEAST TOWARD THE AREA AND PRODUCE SCATTERED/NUMEROUS SHOWERS LATER THIS EVENING THROUGH THE OVERNIGHT HOURS. EXPECT DETERIORATING CLOUD CIGS AND VSBY INTO MVFR/IFR RANGE AFTER 08Z...LASTING INTO MONDAY MORNING. MAY SEE ENOUGH MID-LEVEL INSTABILITY FOR A FEW EMBEDDED THUNDERSTORMS AFTER MIDNIGHT THROUGH MONDAY MORNING...BUT NOT CONFIDENT ENOUGH AT THIS POINT TO INCLUDE IN THE BODY OF THE TAF. && .HYDROLOGY... ISSUED AT 342 AM CDT SUN APR 7 2013 RIVER STATUS... THE TREMPEALEAU RIVER NEAR DODGE WILL REMAIN ABOVE FLOOD STAGE AND ALLOW FOR MINOR FLOODING TO CONTINUE THROUGH MONDAY MORNING. MEANWHILE ON THE BLACK...ANOTHER BRIEF ICE JAM LOOKS LIKE IT MAY HAVE FORMED AROUND NEILLSVILLE...WITH A SPIKE UP OF 4 FEET BUT STILL WELL WITHIN THE RIVER BANK. DOWNSTREAM...SO FAR THE BLACK REMAINS WITHIN THE RIVER BANK. SNOW PACK... RECENT COOPERATIVE OBSERVER REPORTS SHOW SNOW PACK IS MAINLY ALONG AND NORTHEAST OF THE INTERSTATE 94 CORRIDOR WITH 2 TO 7 INCHES OF SNOW DEPTH IN PLACES. THE DEEPEST SNOW PACK IS OVER THE NORTHERN MOST PARTS OF TAYLOR WHERE AROUND A FOOT OF SNOW REMAINS ON THE GROUND. SNOW WATER EQUIVALENT OF 1 TO 2 INCHES IS MAINLY NORTH OF THE INTERSTATE 94 CORRIDOR WITH THE GREATEST SNOW WATER EQUIVALENT OF 2 TO 4 INCHES IN NORTHERN TAYLOR COUNTY. RAINFALL... LESS RAINFALL IS ANTICIPATED TONIGHT INTO MONDAY THAN PREVIOUSLY EXPECTED...WITH UPWARDS OF 1/4 TO 1/2 INCH NORTH OF I-90 AND LESS THAN A 1/4 INCH TO THE SOUTH. WILL STILL NEED TO WATCH TUESDAY THROUGH WEDNESDAY...THOUGH. BY WEDNESDAY MORNING...CURRENTLY ANTICIPATING AMOUNTS BETWEEN 3/4 INCH AND 1.25 INCHES SOUTH OF HIGHWAY 10 TO LESS THAN A 1/2 INCH TO THE NORTH. IF THE SYSTEM BRINGING THIS RAIN SHIFTS FARTHER NORTH...THE HEAVY RAIN AREA WILL SHIFT NORTH AS WELL...PLACING IT WHERE RAIN IS NOT NEEDED. TEMPERATURES... HIGHS TODAY ARE GOING TO BE COOLER...IN THE THE MIDDLE 40S/AROUND 50 NORTH OF I-94 AND IN THE 50S SOUTH OF THERE. WARMER CONDITIONS LOOK ON TAP FOR MONDAY...WITH MOSTLY 50S NORTH OF I-94 AND 60S SOUTH. TEMPERATURES THEN COOL INTO THE 40S FOR TUESDAY AND WEDNESDAY AND POSSIBLY STRUGGLE TO GET TO 40 BY THURSDAY. THE TEMPERATURE MAY NOT MATTER IN A FEW DAYS AS MOST OF THE SNOW PACK MAY BE GONE...UNTIL POTENTIALL A SMALL SNOW PACK RE-ESTABLISHES ITSELF THURSDAY MORNING. FROST DEPTH... AS OF APRIL 4TH...FROST DEPTHS //WHICH ARE OBSERVED EVERY MONDAY AND THURSDAY//ACROSS THE AREA REMAIN DEEP...AVERAGING AROUND 1 FOOT TO 1 1/2 FEET SOUTH OF I-90...AND UP TO 3 FEET ACROSS PORTIONS OF NORTH CENTRAL WISCONSIN. THIS FROST WILL ACT TO ENHANCE RUNOFF OF SNOW MELT AND PRECIPITATION INTO STREAMS AND RIVERS. SUMMARY... MAIN CONCERN FOR FLOODING REMAINS ALONG THE TREMPEALEAU AND BLACK RIVERS AS SNOW MELT CONTINUES...ALONG WITH THE PERIODS OF RAINFALL TONIGHT INTO MONDAY AS WELL AS TUESDAY THROUGH WEDNESDAY. HAVE A HYDROLOGIC OUTLOOK PRODUCT OUT TO HEIGHTEN THIS AWARENESS. ALTHOUGH THE TUESDAY INTO WEDNESDAY MODERATE TO HEAVY RAIN IS FORECAST MAINLY SOUTH OF I-90...CURRENTLY THINKING THAT THE RIVERS SHOULD BE ABLE TO ABSORB IT. A QUICK MODEL OF THE TURKEY RIVER AT GARBER USING THE FORECAST QPF WOULD BRING THE RIVER ABOVE ACTION STAGE BUT NOT TO FLOOD. THUS...DID NOT EXPAND THE HYDROLOGIC OUTLOOK SOUTH. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...DAS HYDROLOGY...AJ