Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/09/13


AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
1007 AM PST THU MAR 7 2013 .DISCUSSION...AS OF 9:10 AM PST THURSDAY...SATL IMAGERY IS INDC THAT THE UPPER LOW IS WEST OF PT REYES AND IS SLOWLY MOVING SOUTH...BUT WILL REMAIN OFF THE COAST. SO FAR...RADAR AND SFC OBS ARE SHOWING ALL RAIN OFF THE COAST. WITH THE TRACK OF THE UPPER LOW FCST TO BE WEST OF THE COAST... THE CORE OF THE COLD AIR WILL REMAIN OVER THE OCEAN. THE QUESTION THEN BECOMES WHAT TO DO WITH THE WINTER WEATHER ADVISORIES THAT ARE CURRENTLY OUT FOR THE SOUTHERN MOUNTAINS. BASED ON THE LATEST MODEL DATA IT APPEARS THAT THE SNOW LEVELS MIGHT BE HIGHER THAN PREVIOUSLY EXPECTED. HOWEVER...ANY CONVECTIVE SHOWERS COULD DROP THE SNOW LEVELS DOWN TEMPORARILY. BOTTOM LINE IS THAT THERE WAS CONSIDERATION FOR DROPPING THE WINTER WEATHER ADVISORIES...HAVE DECIDED TO LET THEM CONTINUE DUE TO THE POSSIBILITY OF CONVECTIVE ACTIVITY DROPPING THE SNOW LEVELS LOW ENOUGH TO GET A QUICK COUPLE OF INCHES OR MORE. CURRENT FORECAST ON TRACK...NO UPDATES. PREVIOUS DISCUSSION...AS OF 3:37 AM PST THURSDAY...FORECAST FOCUS IS ON SHORTWAVE CURRENTLY LOCATED JUST WEST OF CAPE MENDOCINO. COMPARED TO 24 HOURS AGO THE MODELS ARE NOW BRINGING THE MAIN CORE OF THE LOW CLOSER TO THE BAY AREA LATER THIS AFTERNOON AND EVENING...WHEREAS EARLIER RUNS WERE KEEPING THE BULK OF THE ENERGY AND ASSOCIATED MOISTURE OFFSHORE AND THEN TOWARDS SOUTHERN CALIFORNIA. LATEST SOLUTIONS ARE MORE IN-LINE WITH WHAT WAS ADVERTISED 1-2 DAYS AGO. SO EXPECT ISOLATED SHOWERS THROUGH THE MORNING HOURS...THEN SHOWER ACTIVITY SHOULD BECOME MORE NUMEROUS ALONG THE NORTH BAY COAST BY MIDDAY AND CONTINUE TO INCREASE THROUGH THE LATE AFTERNOON HOURS AS THE CORE OF THE LOW APPROACHES THE BAY AREA. THE RAP MODEL IS THE MOST BULLISH FOR PRECIP IN THE NORTH BAY WHILE THE NCEP SUITE OF MODELS KEEPS THE BULK OF THE SHOWER ACTIVITY FROM ABOUT SANTA CRUZ SOUTHWARD. HIGHER CONFIDENCE THAT THE MOST NUMEROUS SHOWER ACTIVITY WILL BE FOCUSED OVER THE SOUTHERN REGIONS OF THE DISTRICT AS THE CORE OF THE LOW WILL THEN DIVE SOUTHWARD DOWN THE COASTLINE. QPF TOTALS WILL BE LIGHT WITH 0.10-0.25 ON AVERAGE. SINCE THE CORE OF THE LOW STAYS OFF SHORE THE COLDEST AIR ALOFT WONT INFILTRATE THE REGION...THUS SNOW LEVELS SHOULD GENERALLY STAY 3000 FEET AND HIGHER. HAVE FINE TUNED THE INHERITED WINTER WX ADVISORY FOR THE HIGHER TERRAIN OF MONTEREY AND SAN BENITO COUNTY TO DELAY THE START AND SHORTEN THE END TIME TO THE PRE-DAWN HOURS OF TOMORROW. THE MAIN PRECIP WILL WIND DOWN BY 12Z FRIDAY WITH JUST SOME SCATTERED SHOWERS LEFT OVER ON FRIDAY MORNING FOR THE MONTEREY BAY REGION...DECREASING TO ISOLATED BY FRIDAY AFTERNOON. HIGH PRESSURE WILL BEGIN TO BUILD ON THE BACKSIDE OF THE TROUGH WITH A CLEAR AND COLD MARCH NIGHT IN STORE FRIDAY NIGHT INTO SATURDAY MORNING. HIGH PRESSURE RIDGE WILL NOSE IN SATURDAY THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK RESULTING IN DRY WEATHER WITH TEMPERATURES CLIMBING TO NEAR OR ABOVE NORMAL BY EARLY NEXT WEEK WITH MODERATING NIGHT TIME LOWS. LONG RANGE FORECAST LOOKING DRY ONCE AGAIN. UNUSUAL PATTERN THE LAST SEVERAL WEEKS WHERE WE GET ONE/TWO STORMS TO BREAK DOWN THE RIDGE BUT NO SUSTAINED STORM CYCLES. && .AVIATION...AS OF 10:05 AM PST THURSDAY...CURRENTLY THE VISIBLE SATELLITE IMAGE IS SHOWING A LOW PRESSURE SYSTEM POSITIONED JUST OFF OF THE SONOMA COAST. THIS LOW PRESSURE SYSTEM IS ADVECTING MID TO UPPER LEVEL CLOUDS INTO THE MONTEREY AND SAN FRANCISCO BAY AREAS. SHOWERS WILL BECOME A POSSIBILITY THIS AFTERNOON AND EVENING AS THE LOW MOVE SOUTH ALONG THE COAST. VICINITY OF KSFO...VFR IS FORECAST TODAY WITH SOUTH SOUTHEAST WINDS. SHOWERS ARE EXPECTED BY 0000Z WITH LIGHT RAIN BY 0500Z. NORTH WINDS WILL FILL INTO THE BAY AREA BY 1000Z. KSFO BRIDGE APPROACH...SIMILAR TO KSFO. MONTEREY BAY AREA TERMINALS...VFR IS FORECAST TODAY WITH SOUTHERLY WINDS. SHOWERS WILL BE A POSSIBILITY BETWEEN 2100 AND 0000Z WITH LIGHT RAIN BEGINNING AROUND 0000Z. && .MTR WATCHES/WARNINGS/ADVISORIES... .TDAY...WINTER WEATHER ADVISORY...ABOVE 3000 FEET IN MONTEREY AND AND SAN BENITO COUNTY FROM 1 PM THURSDAY THROUGH 3 AM FRIDAY. && $$ PUBLIC FORECAST: STROBIN/RWW AVIATION/MARINE: LARRY VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.SANFRANCISCOBAYAREA.GOV WWW.TWITTER.COM/NWSBAYAREA WWW.YOUTUBE.COM/NWSBAYAREA
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
920 AM PST THU MAR 7 2013 .DISCUSSION...AS OF 9:10 AM PST THURSDAY...SATL IMAGERY IS INDC THAT THE UPPER LOW IS WEST OF PT REYES AND IS SLOWLY MOVING SOUTH...BUT WILL REMAIN OFF THE COAST. SO FAR...RADAR AND SFC OBS ARE SHOWING ALL RAIN OFF THE COAST. WITH THE TRACK OF THE UPPER LOW FCST TO BE WEST OF THE COAST... THE CORE OF THE COLD AIR WILL REMAIN OVER THE OCEAN. THE QUESTION THEN BECOMES WHAT TO DO WITH THE WINTER WEATHER ADVISORIES THAT ARE CURRENTLY OUT FOR THE SOUTHERN MOUNTAINS. BASED ON THE LATEST MODEL DATA IT APPEARS THAT THE SNOW LEVELS MIGHT BE HIGHER THAN PREVIOUSLY EXPECTED. HOWEVER...ANY CONVECTIVE SHOWERS COULD DROP THE SNOW LEVELS DOWN TEMPORARILY. BOTTOM LINE IS THAT THERE WAS CONSIDERATION FOR DROPPING THE WINTER WEATHER ADVISORIES...HAVE DECIDED TO LET THEM CONTINUE DUE TO THE POSSIBILITY OF CONVECTIVE ACTIVITY DROPPING THE SNOW LEVELS LOW ENOUGH TO GET A QUICK COUPLE OF INCHES OR MORE. CURRENT FORECAST ON TRACK...NO UPDATES. PREVIOUS DISCUSSION...AS OF 3:37 AM PST THURSDAY...FORECAST FOCUS IS ON SHORTWAVE CURRENTLY LOCATED JUST WEST OF CAPE MENDOCINO. COMPARED TO 24 HOURS AGO THE MODELS ARE NOW BRINGING THE MAIN CORE OF THE LOW CLOSER TO THE BAY AREA LATER THIS AFTERNOON AND EVENING...WHEREAS EARLIER RUNS WERE KEEPING THE BULK OF THE ENERGY AND ASSOCIATED MOISTURE OFFSHORE AND THEN TOWARDS SOUTHERN CALIFORNIA. LATEST SOLUTIONS ARE MORE IN-LINE WITH WHAT WAS ADVERTISED 1-2 DAYS AGO. SO EXPECT ISOLATED SHOWERS THROUGH THE MORNING HOURS...THEN SHOWER ACTIVITY SHOULD BECOME MORE NUMEROUS ALONG THE NORTH BAY COAST BY MIDDAY AND CONTINUE TO INCREASE THROUGH THE LATE AFTERNOON HOURS AS THE CORE OF THE LOW APPROACHES THE BAY AREA. THE RAP MODEL IS THE MOST BULLISH FOR PRECIP IN THE NORTH BAY WHILE THE NCEP SUITE OF MODELS KEEPS THE BULK OF THE SHOWER ACTIVITY FROM ABOUT SANTA CRUZ SOUTHWARD. HIGHER CONFIDENCE THAT THE MOST NUMEROUS SHOWER ACTIVITY WILL BE FOCUSED OVER THE SOUTHERN REGIONS OF THE DISTRICT AS THE CORE OF THE LOW WILL THEN DIVE SOUTHWARD DOWN THE COASTLINE. QPF TOTALS WILL BE LIGHT WITH 0.10-0.25 ON AVERAGE. SINCE THE CORE OF THE LOW STAYS OFF SHORE THE COLDEST AIR ALOFT WONT INFILTRATE THE REGION...THUS SNOW LEVELS SHOULD GENERALLY STAY 3000 FEET AND HIGHER. HAVE FINE TUNED THE INHERITED WINTER WX ADVISORY FOR THE HIGHER TERRAIN OF MONTEREY AND SAN BENITO COUNTY TO DELAY THE START AND SHORTEN THE END TIME TO THE PRE-DAWN HOURS OF TOMORROW. THE MAIN PRECIP WILL WIND DOWN BY 12Z FRIDAY WITH JUST SOME SCATTERED SHOWERS LEFT OVER ON FRIDAY MORNING FOR THE MONTEREY BAY REGION...DECREASING TO ISOLATED BY FRIDAY AFTERNOON. HIGH PRESSURE WILL BEGIN TO BUILD ON THE BACKSIDE OF THE TROUGH WITH A CLEAR AND COLD MARCH NIGHT IN STORE FRIDAY NIGHT INTO SATURDAY MORNING. HIGH PRESSURE RIDGE WILL NOSE IN SATURDAY THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK RESULTING IN DRY WEATHER WITH TEMPERATURES CLIMBING TO NEAR OR ABOVE NORMAL BY EARLY NEXT WEEK WITH MODERATING NIGHT TIME LOWS. LONG RANGE FORECAST LOOKING DRY ONCE AGAIN. UNUSUAL PATTERN THE LAST SEVERAL WEEKS WHERE WE GET ONE/TWO STORMS TO BREAK DOWN THE RIDGE BUT NO SUSTAINED STORM CYCLES. && .AVIATION...AS OF 3:50 AM PST THURSDAY...A STORM SYSTEM IS FORECAST TO MOVE TOWARD THE REGION LATER THIS MORNING. THIS STORM WILL BRING RAIN SHOWERS TO THE TERMINALS...MAINLY IMPACTING KSJC SOUTHWARD. MAINLY LIGHT AND VARIABLE WINDS ALONG WITH VFR CIGS WILL ACCOMPANY THIS STORM. SHOWER ACTIVITY WILL SUBSIDE THIS EVENING INTO THE OVERNIGHT HOURS. VICINITY OF KSFO...VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST. RAIN SHOWERS ARE FORECAST TO IMPACT THE BAY BY 17Z...WITH A STRAY SHOWER POSSIBLE BEFORE THIS TIME. LIGHT SOUTHERLY WINDS WILL BECOME WESTERLY BY THIS AFTERNOON. RAIN SHOWER ACTIVITY WILL MOVE OUT OF THE REGION BY 10Z FRIDAY. KSFO BRIDGE APPROACH...SIMILAR TO KSFO. MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST. RAIN SHOWER ACTIVITY WILL INCREASE EARLY THIS AFTERNOON AND CONTINUE THROUGH THE OVERNIGHT HOURS. && .MTR WATCHES/WARNINGS/ADVISORIES... .TDAY...WINTER WEATHER ADVISORY...ABOVE 3000 FEET IN MONTEREY AND AND SAN BENITO COUNTY FROM 1 PM TODAY THROUGH 3 AM FRIDAY. && $$ PUBLIC FORECAST: STROBIN/RWW AVIATION/MARINE: LARRY/RILEY VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.SANFRANCISCOBAYAREA.GOV WWW.TWITTER.COM/NWSBAYAREA WWW.YOUTUBE.COM/NWSBAYAREA
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
351 AM PST THU MAR 7 2013 .DISCUSSION...AS OF 3:37 AM PST THURSDAY...FORECAST FOCUS IS ON SHORTWAVE CURRENTLY LOCATED JUST WEST OF CAPE MENDOCINO. COMPARED TO 24 HOURS AGO THE MODELS ARE NOW BRINGING THE MAIN CORE OF THE LOW CLOSER TO THE BAY AREA LATER THIS AFTERNOON AND EVENING...WHEREAS EARLIER RUNS WERE KEEPING THE BULK OF THE ENERGY AND ASSOCIATED MOISTURE OFFSHORE AND THEN TOWARDS SOUTHERN CALIFORNIA. LATEST SOLUTIONS ARE MORE IN-LINE WITH WHAT WAS ADVERTISED 1-2 DAYS AGO. SO EXPECT ISOLATED SHOWERS THROUGH THE MORNING HOURS...THEN SHOWER ACTIVITY SHOULD BECOME MORE NUMEROUS ALONG THE NORTH BAY COAST BY MIDDAY AND CONTINUE TO INCREASE THROUGH THE LATE AFTERNOON HOURS AS THE CORE OF THE LOW APPROACHES THE BAY AREA. THE RAP MODEL IS THE MOST BULLISH FOR PRECIP IN THE NORTH BAY WHILE THE NCEP SUITE OF MODELS KEEPS THE BULK OF THE SHOWER ACTIVITY FROM ABOUT SANTA CRUZ SOUTHWARD. HIGHER CONFIDENCE THAT THE MOST NUMEROUS SHOWER ACTIVITY WILL BE FOCUSED OVER THE SOUTHERN REGIONS OF THE DISTRICT AS THE CORE OF THE LOW WILL THEN DIVE SOUTHWARD DOWN THE COASTLINE. QPF TOTALS WILL BE LIGHT WITH 0.10-0.25 ON AVERAGE. SINCE THE CORE OF THE LOW STAYS OFF SHORE THE COLDEST AIR ALOFT WONT INFILTRATE THE REGION...THUS SNOW LEVELS SHOULD GENERALLY STAY 3000 FEET AND HIGHER. HAVE FINE TUNED THE INHERITED WINTER WX ADVISORY FOR THE HIGHER TERRAIN OF MONTEREY AND SAN BENITO COUNTY TO DELAY THE START AND SHORTEN THE END TIME TO THE PRE-DAWN HOURS OF TOMORROW. THE MAIN PRECIP WILL WIND DOWN BY 12Z FRIDAY WITH JUST SOME SCATTERED SHOWERS LEFT OVER ON FRIDAY MORNING FOR THE MONTEREY BAY REGION...DECREASING TO ISOLATED BY FRIDAY AFTERNOON. HIGH PRESSURE WILL BEGIN TO BUILD ON THE BACKSIDE OF THE TROUGH WITH A CLEAR AND COLD MARCH NIGHT IN STORE FRIDAY NIGHT INTO SATURDAY MORNING. HIGH PRESSURE RIDGE WILL NOSE IN SATURDAY THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK RESULTING IN DRY WEATHER WITH TEMPERATURES CLIMBING TO NEAR OR ABOVE NORMAL BY EARLY NEXT WEEK WITH MODERATING NIGHT TIME LOWS. LONG RANGE FORECAST LOOKING DRY ONCE AGAIN. UNUSUAL PATTERN THE LAST SEVERAL WEEKS WHERE WE GET ONE/TWO STORMS TO BREAK DOWN THE RIDGE BUT NO SUSTAINED STORM CYCLES. && .AVIATION...AS OF 3:50 AM PST THURSDAY...A STORM SYSTEM IS FORECAST TO MOVE TOWARD THE REGION LATER THIS MORNING. THIS STORM WILL BRING RAIN SHOWERS TO THE TERMINALS...MAINLY IMPACTING KSJC SOUTHWARD. MAINLY LIGHT AND VARIABLE WINDS ALONG WITH VFR CIGS WILL ACCOMPANY THIS STORM. SHOWER ACTIVITY WILL SUBSIDE THIS EVENING INTO THE OVERNIGHT HOURS. VICINITY OF KSFO...VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST. RAIN SHOWERS ARE FORECAST TO IMPACT THE BAY BY 17Z...WITH A STRAY SHOWER POSSIBLE BEFORE THIS TIME. LIGHT SOUTHERLY WINDS WILL BECOME WESTERLY BY THIS AFTERNOON. RAIN SHOWER ACTIVITY WILL MOVE OUT OF THE REGION BY 10Z FRIDAY. KSFO BRIDGE APPROACH...SIMILAR TO KSFO. MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST. RAIN SHOWER ACTIVITY WILL INCREASE EARLY THIS AFTERNOON AND CONTINUE THROUGH THE OVERNIGHT HOURS. && .MTR WATCHES/WARNINGS/ADVISORIES... .TDAY...WINTER WEATHER ADVISORY...ABOVE 3000 FEET IN MONTEREY AND AND SAN BENITO COUNTY FROM 1 PM THURSDAY THROUGH 3 AM FRIDAY. && $$ PUBLIC FORECAST: RWW AVIATION/MARINE: RILEY VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.SANFRANCISCOBAYAREA.GOV WWW.TWITTER.COM/NWSBAYAREA WWW.YOUTUBE.COM/NWSBAYAREA
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
337 AM PST THU MAR 7 2013 .DISCUSSION...AS OF 3:37 AM PST THURSDAY...FORECAST FOCUS IS ON SHORTWAVE CURRENTLY LOCATED JUST WEST OF CAPE MENDOCINO. COMPARED TO 24 HOURS AGO THE MODELS ARE NOW BRINGING THE MAIN CORE OF THE LOW CLOSER TO THE BAY AREA LATER THIS AFTERNOON AND EVENING...WHEREAS EARLIER RUNS WERE KEEPING THE BULK OF THE ENERGY AND ASSOCIATED MOISTURE OFFSHORE AND THEN TOWARDS SOUTHERN CALIFORNIA. LATEST SOLUTIONS ARE MORE IN-LINE WITH WHAT WAS ADVERTISED 1-2 DAYS AGO. SO EXPECT ISOLATED SHOWERS THROUGH THE MORNING HOURS...THEN SHOWER ACTIVITY SHOULD BECOME MORE NUMEROUS ALONG THE NORTH BAY COAST BY MIDDAY AND CONTINUE TO INCREASE THROUGH THE LATE AFTERNOON HOURS AS THE CORE OF THE LOW APPROACHES THE BAY AREA. THE RAP MODEL IS THE MOST BULLISH FOR PRECIP IN THE NORTH BAY WHILE THE NCEP SUITE OF MODELS KEEPS THE BULK OF THE SHOWER ACTIVITY FROM ABOUT SANTA CRUZ SOUTHWARD. HIGHER CONFIDENCE THAT THE MOST NUMEROUS SHOWER ACTIVITY WILL BE FOCUSED OVER THE SOUTHERN REGIONS OF THE DISTRICT AS THE CORE OF THE LOW WILL THEN DIVE SOUTHWARD DOWN THE COASTLINE. QPF TOTALS WILL BE LIGHT WITH 0.10-0.25 ON AVERAGE. SINCE THE CORE OF THE LOW STAYS OFF SHORE THE COLDEST AIR ALOFT WONT INFILTRATE THE REGION...THUS SNOW LEVELS SHOULD GENERALLY STAY 3000 FEET AND HIGHER. HAVE FINE TUNED THE INHERITED WINTER WX ADVISORY FOR THE HIGHER TERRAIN OF MONTEREY AND SAN BENITO COUNTY TO DELAY THE START AND SHORTEN THE END TIME TO THE PRE-DAWN HOURS OF TOMORROW. THE MAIN PRECIP WILL WIND DOWN BY 12Z FRIDAY WITH JUST SOME SCATTERED SHOWERS LEFT OVER ON FRIDAY MORNING FOR THE MONTEREY BAY REGION...DECREASING TO ISOLATED BY FRIDAY AFTERNOON. HIGH PRESSURE WILL BEGIN TO BUILD ON THE BACKSIDE OF THE TROUGH WITH A CLEAR AND COLD MARCH NIGHT IN STORE FRIDAY NIGHT INTO SATURDAY MORNING. HIGH PRESSURE RIDGE WILL NOSE IN SATURDAY THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK RESULTING IN DRY WEATHER WITH TEMPERATURES CLIMBING TO NEAR OR ABOVE NORMAL BY EARLY NEXT WEEK WITH MODERATING NIGHT TIME LOWS. LONG RANGE FORECAST LOOKING DRY ONCE AGAIN. UNUSUAL PATTERN THE LAST SEVERAL WEEKS WHERE WE GET ONE/TWO STORMS TO BREAK DOWN THE RIDGE BUT NO SUSTAINED STORM CYCLES. && .AVIATION...AS OF 9:30 PM PST WEDNESDAY...SOME HIGH CLOUDS WERE STILL STREAMING OVER THE AREA ASSOCIATED WITH A JET STREAK EXITING TO THE EAST. INCREASING STABILITY TONIGHT MAY LEAD TO A FEW FOG PATCHES INLAND VALLEYS VERY LATE TONIGHT WHERE MOSTLY CLEAR SKIES PREVAIL. BEST CHANCES FOR RADIATIONAL COOLING WILL BE OVER THE NORTHERN HALF OF THE AREA WHERE SUBSIDENCE PREVAILS TONIGHT. A MUCH COLDER UPPER LOW WILL MOVE SOUTH OVER THE COASTAL WATERS THURSDAY BRINGING SHOWERS BACK INTO THE PICTURE THURSDAY AND THURSDAY NIGHT. A SLIGHT INCREASE IN INSTABILITY PARAMETERS SUGGESTS POSSIBLE ISOLATED THUNDER AFTER 21Z PER CHECK ON MODIFIED FORECAST SOUNDINGS. INSTABILITY GRADUALLY DECLINES THURSDAY NIGHT AS THE CORE OF THE COLDEST AIR SHIFTS WEST AND THEN SOUTH OF THE AREA REACHING SOCAL FRIDAY MORNING. VICINITY OF KSFO...VFR. LIGHT WINDS. DRY RUNWAYS ARE EXPECTED TIL INSTABILITY/POSSIBLE SHOWER ACTIVITY ARRIVES THURSDAY AFTERNOON AND EVENING. KSFO BRIDGE APPROACH...VFR. AREA WEATHER PATTERN IS NOT VERY FAVORABLE FOR FOG PATCHES. IF ANY DO DEVELOP THURSDAY MORNING THEY SHOULD QUICKLY MIX OUT AFTER SUNRISE. MONTEREY BAY AREA TERMINALS...HIGH CLOUDS CONTINUE TO STREAM IN FROM THE WSW. VFR. BEST CHANCES FOR WET WEATHER ARRIVES BY LATE THURSDAY MORNING OR EARLY AFTERNOON. && .MTR WATCHES/WARNINGS/ADVISORIES... .TDAY...WINTER WEATHER ADVISORY...ABOVE 3000 FEET IN MONTEREY AND AND SAN BENITO COUNTY FROM 1 PM THURSDAY THROUGH 3 AM FRIDAY. && $$ PUBLIC FORECAST: RWW AVIATION/MARINE: CANEPA VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.SANFRANCISCOBAYAREA.GOV WWW.TWITTER.COM/NWSBAYAREA WWW.YOUTUBE.COM/NWSBAYAREA
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
245 AM EST THU MAR 7 2013 ...DRY WEATHER AND SLOWLY WARMING TEMPS THE NEXT SEVERAL DAYS... .SYNOPSIS... 07Z WATER VAPOR AND H4 RAP ANALYSIS SHOW THAT MUCH OF THE COUNTY IS NOW BENEATH A BROAD LONGWAVE RIDGE EXTENDING FROM THE THE CONTINENTAL DIVIDE EASTWARD TO THE UPPER MIDWEST/TN VALLEY. ON EITHER SIDE OF THIS RIDGE WE FIND TROUGHING IN PLACE OVER THE PACIFIC/NORTHWEST...AND ALSO TROUGHING/CLOSED UPPER LOW EXITING THE MID-ATLANTIC TOWARD THE NORTHEASTERN STATES. OUR FORECAST AREA RESIDES WITHIN A ZONE OF DEEP NW FLOW BETWEEN THE DEPARTING TROUGH AND THE CENTRAL CONUS RIDGE. REGIONAL SOUNDING FROM THIS PAST EVENING CONFIRM THE WATER VAPOR PRESENTATION THAT THE COLUMN OVER THE FL PENINSULA IS EXTREMELY DRY. PW VALUES WERE GENERALLY WELL UNDER HALF THE CLIMO VALUES FOR EARLY MARCH. THIS DRY AIR ALONG WITH VIRTUALLY NO SYNOPTIC SUPPORT FOR LIFT IS RESULTING IN CLEAR SKIES EARLY THIS MORNING. AT THE SURFACE...WEDNESDAYS COLD FRONT IS NOW WELL SOUTH OF THE PENINSULA WITH HIGH PRESSURE CENTERED ALONG THE MS VALLEY TRYING TO RIDGE IN FROM THE NW. TEMPERATURES ARE COOL AS THE DRY ATMOSPHERE HELPS WITH THE RADIATIVE PROCESS...HOWEVER THE GRADIENT IS TIGHT ENOUGH SO FAR TO PREVENT MUCH IN THE WAY OF BOUNDARY LAYER DE-COUPLING...EVEN UP NORTH. THIS LACK OF DE-COUPLING SHOULD GENERALLY HELP KEEP TEMPS UP AND PREVENT MUCH FROST. IT IS STILL POSSIBLE WITH THE RIDGE BUILDING THAT A BRIEF DECOUPLING COULD OCCUR FOR OUR NORTHERN NATURE COAST ZONES TOWARD DAWN...ALLOWING A SHOT AT BRIEFLY DROPPING DOWN TOWARD FREEZING. && .SHORT TERM (TODAY THROUGH SATURDAY)... TODAY/TONIGHT... QUIET...DRY AND COOL PERIOD THE NEXT 24-30 HOURS WITH TEMPERATURES BELOW NORMAL FOR EARLY MARCH. FORECAST AREA WILL REMAIN EMBEDDED WITHIN A DEEP LAYER NW FLOW PATTERN ON THE EASTERN PERIPHERY OF A BUILDING/AMPLIFYING UPPER RIDGE. LOOKING FOR GENERALLY ABUNDANT SUNSHINE TODAY...ESPECIALLY DURING THE MORNING HOURS. DURING THE AFTERNOON AND EVENING WE MAY SEE SOME SCT HIGH LEVEL CIRRUS TO FILTER THE SUN ARRIVING AS A WEAK UPPER LEVEL SHORTWAVE...NOW SEEN IN WV IMAGE OVER THE LOWER MS VALLEY...TRACKS SOUTHEASTWARD TOWARD THE REGION. THIS WEAK IMPULSE WILL EXIT TO OUR EAST LATE TONIGHT/EARLY FRIDAY WITH ANY HIGH CIRRUS FOLLOWING INTO THE ATLANTIC. HIGH TEMPS TODAY WILL REACH THE MID/UPPER 60S NORTH OF I-4 AND GENERALLY LOWER 70S FURTHER SOUTH. SOME AFTERNOON ONSHORE WIND COMPONENT NEAR THE COAST IS LIKELY TO KEEP READINGS A FEW DEGREES COOLER AT THE BEACHES...ESPECIALLY FROM MANATEE COUNTY NORTHWARD. A DRY ATMOSPHERE AND SURFACE RIDGING STILL BUILDING IN FROM THE NORTH WILL ALLOW FOR ANOTHER COOL OVERNIGHT PERIOD. ENOUGH RIDGING IS LIKELY INTO THE NATURE COAST TO ALLOW FOR A POTENTIAL BRIEF DECOUPLING TOWARD DAWN. THEREFORE A FEW NORMALLY COLDER SPOTS FROM BROOKSVILLE NORTH MAY APPROACH FREEZING. SMALL DEWPOINT DEPRESSION AND LIGHT WINDS BY THIS TIME SUGGEST FOR SOME PATCHY FROST FORMATION. HAVE ADDED THIS POTENTIAL TO THE FORECAST GRIDS FOR LOCATIONS FORECAST TO REACH 35 DEGREES OR LOWER. PATCHY FROST WILL ALSO BE POSSIBLE FOR THE NORMALLY COLDER SPOTS WITHIN HARDEE/DESOTO/HIGHLANDS COUNTIES...ALTHOUGH THESE AREAS ARE MORE CONDITIONAL ON THE OCCURRENCE OF TRUE BOUNDARY LAYER DECOUPLING. FRIDAY THROUGH SATURDAY... VERY PLEASANT AND SEASONABLE CONDITIONS TO END THE WEEK WITH TEMPERATURES RETURNING TO NORMAL...OR EVEN SLIGHTLY ABOVE NORMAL DAYTIME READING BY SATURDAY AFTERNOON. IMPRESSIVE MID/UPPER LEVEL RIDGE WILL CONTINUE TO AMPLIFY AND BUILD EAST OVER-TOP THE FORECAST AREA. THIS STACKED RIDGING COMBINED WITH THE SURFACE HIGH STILL RIDGING IN FROM THE NORTH WILL KEEP OUR AREA PROTECTED WITH NEAR ZERO CHANCE OF RAIN INTO THE WEEKEND. HIGH TEMPS WILL REBOUND NICELY ON FRIDAY AFTER THE COOL EARLY MORNING START. SOME LOCATIONS MAY SEE A 35-40 DEGREE DIURNAL SWING. CURRENTLY EXPECTING LOWER 70S NORTH AND MIDDLE 70S SOUTH. ONCE AGAIN...THE POTENTIAL FOR A WEAK ONSHORE COMPONENT TO THE WIND DEVELOPING FOR THE AFTERNOON MAY KEEP THE BEACHES A FEW DEGREES COOLER. LOW TEMPS FRIDAY NIGHT WILL STILL BE COOL...BUT DO NOT ANTICIPATE ANY CHANCE OF FREEZING TEMPS OR EVEN ANY FROST AS READING WARM 5-10 DEGREES FROM THURSDAY NIGHT LOWS. HIGH TEMPERATURES SATURDAY WILL RESPOND TO THIS LESS CHILLY START...AND THE MAXIMIZED HEIGHT FIELDS/SUPPRESSION...TO EASILY REACH THE MIDDLE 70S NORTH AND NEAR 80 IN THE SOUTH. LOW LEVEL SURFACE RIDGE TAKES A POSITION TO OUR NORTH/NORTHEAST ON SATURDAY RESULTING IN STRONGER EASTERLY FLOW. 975-925MB BOUNDARY LAYER WINDS ARE FORECAST TO BE STRAIGHT EAST AT 10-15 KNOTS. 10-15 KNOTS SHOULD BE ENOUGH (GIVEN THE DEGREE OF TERRESTRIAL WARMING) TO PREVENT ANY SEA-BREEZE CIRCULATION FROM MOVING ONSHORE...AND ALLOW WARMER BEACH TEMPS THAN PREVIOUS DAYS. ENJOY! && .LONG TERM (SUNDAY THROUGH NEXT WEDNESDAY)... DEEP LAYER RIDGING FROM THE GULF TO THE LOWER GREAT LAKES SAT NIGHT SLOWLY TREKS EASTWARD...SLIDING OFF THE EASTERN SEABOARD MON. THIS PROVIDES A DRY AIR MASS WITH INITIALLY NEAR NORMAL TEMPERATURES THAT WARM SLIGHTLY. NORTH AND NE WINDS VEER TO SOUTHERLY BY MON AND MAY BECOME ROBUST ON THE GULF AT TIMES. FOR TUE AND WED...AN UPPER LEVEL LONG WAVE TROUGH WITH AN ATTENDANT FRONTAL BOUNDARY MOVES INTO THE GULF-GREAT LAKES REGION THEN SHIFTS OUT OVER THE ATLANTIC WED...SWEEPING THE FRONTAL BOUNDARY ACROSS THE STATE MAINLY DURING THE DAY TUE. THE PORTION OF THE BOUNDARY MOVING OVER THE AREA APPEARS RATHER WEAK AND WILL LIMIT PRECIPITATION TO JUST SLIGHT CHANCE OF SHOWERS. WINDS SHIFT TO NORTHERLY IN THE WAKE OF THE FRONT AND ARE EXPECT TO STAY BELOW ADVISORY SPEEDS. TEMPERATURES COOL SLIGHT BUT STAY CLOSE TO NORMAL. && .MARINE... CAUTIONARY LEVEL NORTHERLY WINDS AWAY FROM THE SHORE WILL DIMINISH BELOW 15 KNOTS BY MIDDAY. DUE TO RESIDUAL WAVE ACTION OBSERVED AT REGIONAL BUOYS EARLY THIS MORNING...HAVE EXTENDED THE SMALL CRAFT ADVISORY UNTIL MID-MORNING FOR THE OFFSHORE LEGS FROM BONITA BEACH TO TARPON SPRINGS. ALL HEADLINES SHOULD THEN BE DROPPED FOR THE AFTERNOON HOURS. BELOW HEADLINE CRITERIA WINDS AND SEAS ARE FORECAST ACROSS THE EASTERN GULF THROUGH FRIDAY AFTERNOON AS HIGH PRESSURE RIDGES IN FROM THE NORTH. THIS RIDGE WILL THEN TAKE UP A POSITION FRIDAY NIGHT INTO EARLY SUNDAY THAT WILL BE FAVORABLE FOR THE DEVELOPMENT OF NOCTURNAL/EARLY MORNING EASTERLY WINDS SURGES. THE FORECAST WILL REFLECT THIS POTENTIAL WITH NEAR CAUTIONARY LEVEL WINDS FRIDAY NIGHT. WINDS WILL DIMINISH FOR MUCH OF THE DAYLIGHT HOURS OF SATURDAY...ONLY TO BUILD TO SOLID CAUTIONARY LEVELS LATER SATURDAY EVENING AND NIGHT. && .AVIATION... VFR CONDITIONS FOR THE NEXT 24 HOURS WITH AFTERNOON CIRRUS. WINDS NORTHEAST-NORTHWEST AT 10KT OR LESS. && .FIRE WEATHER... AN EXTENDED PERIOD OF CRITICALLY LOW RELATIVE HUMIDITY AWAY FROM THE COAST IS EXPECTED FROM LATE THIS MORNING THROUGH THE EARLY EVENING HOURS. ERC VALUES ARE ABOVE 37 FOR PINELLAS AND POLK TODAY...HOWEVER ONLY POLK IS EXPECTED TO SEE THE CRITICAL DURATIONS COINCIDENT WITH THE HIGH ERC. A RED FLAG WARNING HAS BEEN ISSUED FOR POLK FOR THESE REASONS. ANOTHER DAY OF EXTENDED CRITICALLY LOW RELATIVE HUMIDITY IS ANTICIPATED ON FRIDAY. THE POTENTIAL FOR ZONES TO THAT ARE JUST UNDER ERC VALUES OF 37 TODAY TO RISE A FEW DIGITS ON FRIDAY...HAS PROMPTED THE ISSUANCE OF A FIRE WEATHER WATCH FOR POLK...PINELLAS... HIGHLANDS...AND LEE COUNTIES FRIDAY AFTERNOON. && .PRELIMINARY POINT TEMPS/POPS... TPA 65 47 72 51 / 0 0 0 0 FMY 71 47 76 53 / 0 0 0 0 GIF 69 42 75 49 / 0 0 0 0 SRQ 66 45 72 52 / 0 0 0 0 BKV 67 34 71 42 / 0 0 0 0 SPG 65 50 72 57 / 0 0 0 0 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...BEACH HAZARDS STATEMENT UNTIL NOON EST TODAY FOR CHARLOTTE- HILLSBOROUGH-LEE-MANATEE-PINELLAS-SARASOTA. FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY AFTERNOON FOR HIGHLANDS-LEE-PINELLAS-POLK. RED FLAG WARNING FROM 11 AM THIS MORNING TO 7 PM EST THIS EVENING FOR POLK. GULF WATERS...SMALL CRAFT ADVISORY UNTIL 11 AM EST THIS MORNING FOR BONITA BEACH TO ENGLEWOOD OUT 20 TO 60 NM-ENGLEWOOD TO TARPON SPRINGS OUT 20 TO 60 NM. && $$ SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA LONG TERM/AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
947 PM CST FRI MAR 8 2013 .DISCUSSION... 924 PM CST NO REAL BIG CHANGES TO GOING FORECAST TONIGHT...WITH ONLY MINOR EDITS TO POP/WX FOR AREAS ACROSS NORTHWEST ILLINOIS. LATEST SATELLITE IMAGERY DEPICTING MID/UPPER LEVEL CLOUD COVER CONTINUING TO STREAM NORTHEAST ACROSS THE REGION THIS EVENING...AS SOUTHWESTERLY FLOW CONTINUES OUT AHEAD OF AN APPROACHING LONGWAVE TROUGH OVER THE WESTERN CONUS. THIS IS USHERING IN A WARMER AND MORE MOIST ENVIRONMENT WITH LATEST RAP ANALYSIS DEPICTING STRONG WAA OCCURRING ACROSS MUCH OF THE PLAINS...AND CAN BE NOTED VIA THE ABUNDANCE OF CLOUD COVER AS WELL AS THE WIDESPREAD PRECIP SHIELD IN THIS LOCATION. ALTHOUGH THE STRONGEST WAA WILL REMAIN JUST TO THE WEST OF THE CWA...LATEST SHORT TERM GUIDANCE IS INDICATING THAT SOME LIGHT PRECIP DEVELOPMENT COULD OCCUR ACROSS NORTHWEST ILLINOIS TONIGHT AS THIS WAA WING CONTINUES TO LIFT NORTH/NORTHEAST. PRECIP DEVELOPMENT LATE TONIGHT ACROSS AREAS ALONG AND WEST OF INTERSTATE 39 DOES SEEM REASONABLE WITH THIS BETTER FORCING ALREADY INCHING CLOSER TO THE CWA. ALTHOUGH THIS FORCING WILL REMAIN RATHER WEAK...IT MAY BE ENOUGH OF A PERSISTENT FEATURE TO OVERCOME SOME DRIER AIR IN PLACE. THERMAL PROFILES WILL SUPPORT PRECIP OF THE LIQUID TYPE...BUT WITH THE POSSIBILITY OF A BRIEF WINDOW OF LIGHT FREEZING RAIN. ALTHOUGH...WARMING TONIGHT SHOULD MITIGATE ANY OVERALL FREEZING RAIN POTENTIAL WITH SURFACE TEMPERATURES EXPECTED TO BE HOVERING AROUND FREEZING IF NOT BEGINNING TO RISE JUST ABOVE BY THE TIME THIS PRECIP ARRIVES. SO HAVE MADE MENTION OF A SLIGHT CHANCE OF LIGHT RAIN/LIGHT FREEZING RAIN FOR LATE TONIGHT INTO EARLY SATURDAY MORNING BEFORE TEMPERATURES CONTINUE TO RISE THROUGH MID SATURDAY MORNING WITH ONLY RAIN THEN EXPECTED. RODRIGUEZ && .PREV DISCUSSION... 234 PM CST THE AREA WILL QUICKLY SHIFT FROM WINTER TO SPRING WEATHER THIS WEEKEND WITH EXPECTED RAINFALL/SNOW MELT WITH WARMING TEMPERATURES POSING A FLOOD THREAT...WITH THUNDERSTORMS NOT OUT OF THE QUESTION BY SUNDAY. UPS AND DOWNS IN TEMPERATURES ARE EXPECTED NEXT WEEK WITH A SERIES OF WEAKER SYSTEMS BRINGING PERIODIC LOW CHANCES FOR PRECIPITATION. SYNOPSIS...EARLY AFTERNOON WATER VAPOR IMAGERY SHOWS UPPER RIDGING BUILDING ACROSS THE MISSISSIPPI RIVER VALLEY INTO THE LOCAL AREA IN RESPONSE TO A DEEP CLOSED UPPER LOW ROTATING INTO THE DESERT SOUTHWEST. THIS TROUGH IS SPLIT FROM A TROUGH THAT IS POSITIONED OVER CENTRAL CANADA WITH A TROUGH AXIS SHIFTING TOWARDS WESTERN SASKATCHEWAN. THESE TWO FEATURES WILL BE THE MAIN DRIVERS OF EXPECTED RAINFALL THIS WEEKEND. AT THE SURFACE...A LARGE AREA OF HIGH PRESSURE IS EXITING THE LOCAL AREA TO THE EAST. WEAK LOW PRESSURE IS OVER SOUTHERN MANITOBA AND IS DRIFTING EASTWARD. TONIGHT AND SATURDAY...QUIET WEATHER WILL CONTINUE TONIGHT WITH THE UPPER RIDGE CRESTING THE AREA THIS EVENING. THE BIG SOUTHWEST TROUGH WILL BE MOVING EASTWARD WITH HEIGHT FALLS AHEAD OF IT AND BEHIND THE RIDGE ALLOWING LOW PRESSURE TO DEVELOP IN THE LEE OF THE ROCKIES. A 50+KT LOW LEVEL JET WILL SET UP ACROSS THE PLAINS RESULTING IN A STRONG PUSH OF HIGH THETA-E LOW LEVEL AIR ACROSS THE SOUTHERN AND CENTRAL PLAINS. HIGH LEVEL MOISTURE WILL BE SPREAD NORTHEASTWARD SUPPORTING AN INCREASE IN MID AND HIGH LEVEL CLOUD COVER OVERNIGHT. THE PRESSURE GRADIENT WILL BE WEAK ACROSS THE AREA EARLY BUT WILL TIGHTEN OVERNIGHT SO WINDS MAY DROP OFF FOR A TIME EARLY BEFORE INCREASING SOMEWHAT OVERNIGHT. LOW TEMPS WILL BE THE MAIN CHALLENGE AND MAY OCCUR DURING THE EVENING BUT SOME WARMING MAY OCCUR LATE AS CLOUDS AND WINDS INCREASE AND WARM ADVECTION IS UNDERWAY ALOFT. WILL GO AHEAD AND SHOW A STEADY OR WARMING TREND OVERNIGHT. LIGHT PRECIP BECOMES A CONCERN BY SATURDAY MORNING AS WAVES OF WARM ADVECTION BECOME MORE FOCUSED AND MOISTURE DEEPENS. THIS IS WHERE TEMPS WILL BECOME CRITICAL BECAUSE CHANCES FOR LIGHT PRECIP MAY BEGIN EARLY ENOUGH TO FALL AS FREEZING RAIN. SIGNALS FOR PRECIP ARE NOT ALL THAT ORGANIZED UNTIL SATURDAY AFTERNOON BUT WESTERN AREAS MAY HAVE DEEP ENOUGH MOISTURE AND ENOUGH WARM ASCENT OCCURRING ALOFT TO SEE LIGHT RAIN...OR FREEZING RAIN IF TEMPS START OUT BELOW FREEZING...BY LATE SATURDAY MORNING. ANY FREEZING PRECIP WILL QUICKLY END AS TEMPS WARM WELL ABOVE FREEZING BY EARLY AFTERNOON. PRECIP CHANCES WILL THEN EXPAND EASTWARD...ESPECIALLY ACROSS THE NORTHERN CWA SATURDAY AFTERNOON BUT CHANCES STILL LOOK RATHER LOW BUT STILL WORTH A MENTION GIVEN STEADILY INCREASING DEEP LAYER MOISTURE /PRECIPITABLE WATER VALUES REACH 0.75 INCHES OR SO BY LATE DAY/ AND WARM ADVECTION. SOUTH TO SOUTHEAST WINDS WILL BECOME BREEZY WHICH WILL HELP HIGHS WARM INTO LOW TO MID 40S NORTH AND MID TO UPPER 40S SOUTH. IT IS ALSO IMPORTANT TO NOTE THAT DEW POINTS WILL BE ON THE RISE AS WELL WHICH WILL COMBINE WITH THE STEADY WINDS AND MILD TEMPS TO PROVIDE INCREASINGLY EFFICIENT SNOW MELT THROUGH THE AFTERNOON. MORE ON THIS BELOW... SATURDAY NIGHT AND SUNDAY...THE SOUTHWEST UPPER LOW WILL BE LIFTING ACROSS THE SOUTHERN HIGH PLAINS AND PHASING WITH THE CENTRAL CANADA UPPER TROUGH WHICH WILL BE SHARPENING AS IT PIVOTS SOUTHEASTWARD. THE MAIN SURFACE LOW IS EXPECTED TO ORGANIZE IN VICINITY OF THE SOUTHERN UPPER LOW ACROSS WESTERN KANSAS BY SATURDAY EVENING WITH AN INVERTED TROUGH EXTENDING NORTHWARD INTO WESTERN ONTARIO. GULF MOISTURE WILL CONTINUE TO STREAM NORTHWARD AHEAD OF THE LOW AS 60KT LOW LEVEL JET SPREADS ACROSS MISSOURI...ILLINOIS...AND LAKE MICHIGAN LATER SATURDAY EVENING. PRECIPITABLE WATER VALUES WILL FURTHER SURGE REACHING THE 1 TO PERHAPS 1.25 INCH RANGE WHICH WILL COMBINE WITH INCREASED ASCENT TO PRODUCE WIDESPREAD RAIN ACROSS THE MID-MISSISSIPPI RIVER VALLEY WHICH WILL THEN SPREAD EASTWARD DURING THE EVENING AND OVERNIGHT HOURS. THE UPPER LOW WILL BE TO THE WEST OF THE AREA BY SUNDAY MORNING WHICH WILL LIKELY BRING A DRY SLOT INTO THE AREA SOMETIME SUNDAY MORNING. INSTABILITY DOES INCREASE AS WELL...POTENTIALLY WITH ENOUGH ELEVATED INSTABILITY TO SUPPORT SOME THUNDER POTENTIAL ON THE LEADING EDGE OF THE DRY SLOT. FURTHERMORE...SOME MINIMAL SURFACE INSTABILITY COULD DEVELOP AS WELL WHICH WOULD POSE AN ADDITIONAL THUNDER THREAT...ESPECIALLY ALONG THE APPROACHING COLD FRONT WHICH WILL CROSS THE AREA LATER IN THE DAY. HOWEVER...THE DEEPER DRY AIR OF THE DRY SLOT MAY PRECLUDE MUCH IF ANY DEVELOPMENT ALONG THE FRONT IF SURFACE BASED INSTABILITY DOES IN FACT DEVELOP. STILL TOO EARLY TO HAVE ANY HIGH DEGREE OF CONFIDENCE IN THUNDER POTENTIAL BUT FEEL THIS BEARS WATCHING GIVEN THE HIGH DEGREE OF DEEP LAYER WIND SHEAR AND FAIRLY STRONG LOW LEVEL WIND FIELD. HIGH TEMPS SUNDAY LOOK TO RANGE FROM THE MID 40S NORTHWEST TO THE MID 50S SOUTHEAST. PRECIP AMOUNTS/FLOODING POTENTIAL...FORECAST GUIDANCE IS IN PRETTY GOOD AGREEMENT WITH THE TRACK OF LOW LEVEL FEATURES BUT DO DIFFER IN THE PLACEMENT OF OTHER FEATURES SUCH AS THE PATH OF THE UPPER JET CORE. QPF OUTPUT DOES DIFFER SOMEWHAT AS A RESULT...ESPECIALLY IN PLACEMENT OF HEAVIEST VALUES. ARRIVAL TIMING MAY ALSO NEED ADJUSTMENT WITH SOME GUIDANCE BEING SLOWER BUT RIGHT NOW THE DIFFERENCES ARE ON THE ORDER OF A FEW HOURS. THE WESTERN AND NORTHERN CWA CONTINUES TO LOOK TO HAVE THE BEST CHANCE AT RECEIVING PEAK RAINFALL AMOUNTS...OR ROUGHLY FROM CHICAGO TO PONTIAC AND POINTS WEST BUT THE ENTIRE CWA DOES LOOK TO SEE RAINFALL. GIVEN THE PRECIPITABLE WATER VALUES AND DURATION OF FORCING...AMOUNTS OF 0.75-1.00 INCHES ARE PLAUSIBLE IN THE NORTH AND WEST WITH LESSER AMOUNTS SOUTHEAST. IF CONVECTION CAN DEVELOP SUNDAY MORNING THEN AMOUNTS WOULD BE HIGHER IN SPOTS BUT IT IS POSSIBLE THAT THE BEST CHANCE FOR CONVECTION COULD END UP BEING ACROSS THE SOUTHERN/EASTERN CWA GIVEN THE LIKELY TRACK OF THE DRY SLOT AND ARRIVAL OF INSTABILITY. SO CONFIDENCE IN SPECIFIC AMOUNTS AND WHERE THEY OCCUR IS STILL LIMITED. HOWEVER...EVEN SOMEWHAT LOWER AMOUNTS THAN THOSE ABOVE ARE STILL A CONCERN GIVEN THE AMOUNT OF WATER IN THE CURRENT SNOW PACK. REFERENCE HYDROLOGY SECTION BELOW AND ESFLOT PRODUCT FOR MORE DETAILS. SUNDAY NIGHT AND MONDAY...TIMING DIFFERENCES BECOME MORE CRITICAL AS THE SYSTEM DEPARTS SUNDAY NIGHT AND MONDAY. IN TERMS OF FRONTAL TIMING...THERE IS GOOD AGREEMENT ON HAVING THE COLD FRONT SWEEP ACROSS THE AREA SUNDAY AFTERNOON WHICH ALLOWS COLDER AIR TO ARRIVE...BUT THE SPEED WITH WHICH IT ARRIVES IS NOT QUITE CLEAR. THE ECMWF/GEM REMAIN SLOWER WITH THE PASSAGE OF THE UPPER TROUGH AXIS DELAYING THE ARRIVAL OF COLDEST AIR...AS WELL AS THE ATTENDANT DEFORMATION FORCING HOLDING IT OFF UNTIL CLOSER TO MONDAY MORNING. THE NAM AND GFS ARE FASTER WITH THE UPPER TROUGH AND ARRIVAL OF COLD AIR. THIS WILL PLAY HAVOC WITH PRECIP TIMING AND TYPE BEHIND THE FRONT INTO MONDAY MORNING. WILL NEED TO MONITOR THIS PERIOD AS THERE IS AT LEAST SOME SUPPORT FOR MEASURABLE PRECIP MONDAY. MDB LONG TERM...MONDAY NIGHT THROUGH FRIDAY... THE EXTENDED PERIOD WILL FEATURE A FAIRLY PROGRESSIVE NORTHWEST TO PERHAPS ZONAL FLOW WITH SEVERAL WEAK SYSTEMS TO AFFECT PART OF THE REGION/GREAT LAKES. TIMING ANY OF THESE FEATURES IS SOMEWHAT DIFFICULT AS THEIR STRENGTH/LOCATION CONTINUES TO FLUCTUATE FROM RUN TO RUN AS WELL AS FROM MODEL TO MODEL. WHILE THERE WILL BE A FEW CHANCES FOR PRECIP...WILL CONTINUE WITH MAINLY A DRY FORECAST DUE TO LOW CONFIDENCE THOUGH HAVE INCLUDED A SLIGHT CHANCE OF SHOWERS ON FRIDAY AS THERE HAS BEEN SOME CONTINUITY DURING THIS TIME PERIOD. SHOULD PRECIP CHANCES/TRENDS INCREASE...PRECIP TYPE WILL BECOME A CONCERN DEPENDING ON TIME OF DAY. TEMPERATURES ARE EQUALLY CHALLENGING...DEPENDING ON THE TIMING OF THESE FEATURES AND THE EXTENT OF COLD AIR THEY BRING WITH THEM. ECMWF HAD BEEN FAIRLY CONSISTENT WITH A PUSH OF COLDER AIR THURSDAY INTO FRIDAY WHICH IS NOW GONE WHILE THE GFS IS NOW MUCH COLDER. HAVE TRENDED MIDDLE OF THE ROAD WITH TEMPS AND GIVEN MID MARCH SUNSHINE... LACK OF ANY SIGNIFICANT COLD AIR PUSH WOULD SUPPORT TEMPS NEAR SEASONAL NORMALS. CMS && .HYDROLOGY... 234 PM CST SOME AREAS OF THE FORECAST AREA MAY SEE 0.75-1.00 INCHES OF RAINFALL FROM SATURDAY THROUGH SUNDAY...WITH THE BULK EXPECTED SATURDAY EVENING/NIGHT. AT THIS POINT...THESE RAINFALL AMOUNTS ARE EXPECTED GENERALLY WEST OF A LINE FROM CHICAGO TO PONTIAC WITH LESSER AMOUNTS SOUTHEAST BUT THERE IS SOME OPPORTUNITY FOR THE LOCATION TO NEED ADJUSTMENT. IN ADDITION...SOME CONVECTIVE RAINFALL IS POSSIBLE WHICH COULD RESULT IN LOCALLY HIGHER AMOUNTS. OBSERVED SNOW CORE WATER EQUIVALENTS RANGE FROM AROUND AN INCH TO AROUND 2.5 INCHES WHERE THE DEEPEST SNOW EXISTS...MAINLY NORTH OF INTERSTATE 80. FROST DEPTH REMAINS IN THE 6 TO 10 INCH RANGE. THE EXPECTATION IS THAT THE SNOW WILL MELT AND RUNOFF WILL BE REALIZED BEFORE THE FROST MELTS SIGNIFICANTLY DUE TO THE INSULATING EFFECTS OF THE SNOW PACK. SNOW MELT WILL COMMENCE BEFORE THE BULK OF THE RAINFALL WHICH COULD ALLOW SOME OF THE RUNOFF INTO AREA RIVERS AND STREAMS TO MAKE PROGRESS DOWNSTREAM BUT THIS WOULD LIKELY BE MINIMAL. MOST MELT WILL LIKELY OCCUR WITH THE RAINFALL SO RIVER RISES WILL OCCUR AND SOME RIVERS COULD EXCEED FLOOD STAGE LATER SUNDAY/MONDAY. AREAL OVERLAND FLOODING IS A POSSIBILITY...MAINLY IN LOW LYING AND POORLY DRAINED AREAS. REFERENCE ESFLOT FOR ADDITIONAL INFORMATION. && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 03Z... * GUSTY S TO SSE WINDS ON SAT AND SAT EVE. * NEARBY LIGHT RAIN POSSIBLY REACHING THE AIRFIELDS SAT AFTERNOON. * A CHANCE FOR FOG DEVELOPING SAT EVE. //DISCUSSION...UPDATED 00Z... HIGH PRESSURE ACROSS THE CENTRAL GREAT LAKES WILL CONTINUE TO TRANSLATE EAST TONIGHT AS LOW PRESSURE DEVELOPS IN THE CENTRAL PLAINS. AS THIS LOW FURTHER DEVELOPS ON SATURDAY WINDS WILL VEER TO MORE OF A SSE DIRECTION AND INCREASE IN SPEED WITH GUSTINESS FAVORED THROUGH THE DAY AND EVEN POTENTIALLY INTO THE NIGHT. MOIST AIR RETURNING AHEAD OF THE LOW WILL GRADUALLY SATURATE THE ATMOSPHERE. BELIEVE THAT BY DAYBREAK SATURDAY THERE WILL BE SCATTERED LIGHT AREAS OF PRECIPITATION AS FAR EAST AS NORTH CENTRAL IL AND BY AFTERNOON POSSIBLY TO CHICAGOLAND. TEMPERATURES IN THE MORNING WILL LIKELY BE JUST BELOW FREEZING AT RFD WHERE SOME MORNING RAIN MAY OCCUR SO MAINTAIN THE CHANCE FOR FREEZING RAIN IN THAT PERIOD. OTHERWISE A MODERATION IN TEMPERATURES THROUGH THE MORNING WILL END ANY THREAT OF THAT. RAIN WILL BE SLOW TO SPREAD EAST THROUGH SAT EVE BUT THEN IS LIKELY TO RAPIDLY EXPAND OVER BY OVERNIGHT WITH MVFR AND POSSIBLE IFR CONDITIONS. PRIOR TO RAIN THERE IS A CHANCE FOR FOG DEVELOPMENT DUE TO SNOW PACK SUBLIMATION AND INCREASING LOW-LEVEL MOISTURE. AT THIS TIME HAVE NOT ADDED INTO THE TAFS BUT FULLY EXPECT VISBY REDUCTIONS OVERNIGHT SAT NIGHT. //ORD AND MDW CONFIDENCE...UPDATED 03Z... * MEDIUM CONFIDENCE IN WIND TRENDS. DIRECTION COULD BE BETWEEN 130 AND 170 THROUGH SAT A.M. * HIGH CONFIDENCE THAT IF RAIN WERE TO REACH THE AIRFIELDS PRIOR TO END OF CURRENT TAFS IT WOULD BE LIGHT AND BE FROM VFR CIGS. * LOW CONFIDENCE IN ANY FOG DEVELOPMENT PRIOR TO 06Z SUN BUT CONFIDENCE INCREASES IN VISIBILITY REDUCTIONS JUST AFTER /OVERNIGHT SAT NIGHT/. //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY...RAIN AND FOG WITH LIKELY IFR. A CHANCE FOR A MIX WITH SNOW DURING THE NIGHT. MONDAY...SLIGHT CHANCE OF RAIN AND SNOW WITH MVFR. TUESDAY-THURSDAY...VFR. MTF && .MARINE... 125 PM CST THE HIGH PRESSURE THAT BROUGHT LIGHT AND VARIABLE WINDS TO LAKE MICHIGAN HAS MOVED EAST OF THE LAKE AND WINDS HAVE BECOME SOUTHERLY. AS DEEPENING LOW PRESSURE MOVES OUT OF THE ROCKIES AND INTO THE SOUTHERN PLAINS...WHILE THE HIGH MOVES SLOWLY TO THE EAST...THE GENERALLY SOUTHERLY WINDS WILL STRENGTHEN THROUGH THE WEEKEND. BY SATURDAY EVENING...THE HIGH WILL MOVE TO THE EASTERN SEABOARD WHILE THE LOW PRESSURE MOVER THE SOUTH HIGH PLAINS DEEPENS AND A TROUGH OF LOW PRESSURE ELONGATES TO ANOTHER...WEAKER LOW JUST NORTH OF MINNESOTA. SOUTHERLY WINDS WILL INCREASE TO AROUND 30 KT AS THE TROUGH OF LOW PRESSURE AND AN ASSOCIATED COLD FRONT APPROACH THE LAKE. THE COLD FRONT IS EXPECTED TO SWEEP ACROSS THE LAKE SUNDAY...WITH WINDS QUICKLY VEERING TO NORTHERLY. WITH HIGH PRESSURE QUICKLY BUILDING IN ACROSS THE LAKE BEHIND THE COLD FRONT...THE NORTHERLY WINDS WILL ONLY BRIEFLY INCREASE TO AROUND 25 KT SUNDAY NIGHT BEFORE DROPPING OFF TO 5 TO 10 KT BY MONDAY NIGHT. KREIN && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
858 PM CST FRI MAR 8 2013 .DISCUSSION... ISSUED 855 PM CST FRI MAR 8 2013 UPDATED THE FORECAST TO INCREASE CLOUD COVER TONIGHT AND ELEVATE LOW TEMPERATURES UP A DEGREE OR TWO. LOWS RANGE FROM NEAR 30F OVER EAST CENTRAL IL TO THE UPPER 30S FROM SPRINGFIELD SW. CONTINUE A CHANCE OF LIGHT RAIN SHOWERS OVERNIGHT OVER THE IL RIVER VALLEY... WITH BEST CHANCES NW OF THE IL RIVER LATE TONIGHT. 1031 MB HIGH PRESSURE OVER SE LOWER MI INTO OHIO AND EASTERN KY THAT PROVIDE A NICE DAY TO CENTRAL/SE IL WITH AMPLE SUNSHINE AND MILDER 40S WILL DRIFT INTO THE EASTERN GREAT LAKES SAT MORNING. 1001 MB LOW PRESSURE OVER SE CO WILL DEEPEN TO 997 MB NEAR THE SE CO/SW KS BORDER BY MIDDAY SAT WITH A FRONTAL BOUNDARY EXTENDING NE INTO FAR NW IA AND INTO MN. A WARM FRONT OVER SW MO INTO SOUTH CENTRAL NE WILL LIFT NE TOWARD SW IL SAT MORNING. STRONG WAA ADVECTION AND ISENTROPIC LIFT TO DEVELOP AND SPREAD LIGHT RAIN SHOWERS FROM CENTRAL AND WESTERN MO/IA INTO THE IL RIVER VALLEY OVERNIGHT INTO SAT MORNING MAINLY AFTER 09Z/3 AM. HRRR APPEARS TO WET WITH SHOWERS OVER MOST OF CWA OVERNIGHT. SINCE SOUNDINGS ARE QUITE DRY ESPECIALLY FROM I-55 EAST...THIS SHOULD KEEP AREAS FROM I-55 EAST DRY TONIGHT. TEMPS CURRENTLY IN THE MID TO UPPER 30S FROM MACOMB TO LINCOLN TO MATTOON NE AND 40-45F SW WILL SLIP ONLY A FEW MORE DEGREES DUE TO INCREASING/THICKENING MID/HIGH CLOUDS AND ESE WINDS OF 5-15 MPH. 07 && .AVIATION... ISSUED 559 PM CST FRI MAR 8 2013 VFR CONDITIONS SHOULD CONTINUE ACROSS THE CENTRAL IL TERMINAL AIRPORTS NEXT 24 HOURS THROUGH SUNSET SAT. BROKEN TO OVERCAST MID/HIGH CLOUDS TO SPREAD ACROSS CENTRAL IL EARLY THIS EVENING AND CONTINUE THROUGH SAT WITH CEILINGS LOWERING TO 8-12K FT OVERNIGHT INTO SAT. BRUNT OF SHOWERS WILL STAY WEST OF CENTRAL IL TONIGHT WITH A CHANCE OF SHOWERS BRUSHING PIA SAT MORNING WHERE VCSH MAINTAINED. SE WINDS AROUND 10 KTS TONIGHT TO INCREASE TO AROUND 15 KTS WITH GUSTS 18-25 KTS AFTER 15Z SAT. 1031 MB HIGH PRESSURE OVER EASTERN LOWER MI/INDIANA AND WESTERN OHIO TO DRIFT EAST INTO THE ATLANTIC STATES SAT AFTERNOON. MEANWHILE 1000 MB LOW PRESSURE DEEPENING OVER SE CO TO DEEPEN TO 997 MB INTO SW KS BY SUNSET SAT. BRUNT OF ITS SHOWERS SHOULD STAY WEST OF CENTRAL IL THROUGH SAT THOUGH WAA/ISENTROPIC LIFT INTO THE IL RIVER VALLEY SAT MORNING COULD BRING A CHANCE OF SHOWERS TO PIA. LOOKS LIKE A LULL IN SHOWER ACTIVITY OVER CENTRAL IL SAT AFTERNOON. 07 && .PREV DISCUSSION... ISSUED 300 PM CST FRI MAR 8 2013 OUR SURFACE PATTERN IS CURRENTLY DOMINATED BY HIGH PRESSURE EXTENDING FROM THE WESTERN GREAT LAKES ON SOUTH TO MISSISSIPPI...WHILE LOW PRESSURE IN THE SOUTHWEST STATES BEGINS TO MOVE ONSHORE AND DEVELOP UNDER A STRENGTHENING JET STREAM. THAT SYSTEM WILL BECOME OUR MAIN WEATHER ISSUE FOR THE NEXT 3 DAYS OR SO. OUTSIDE OF A BRIEF COOL DOWN ON MONDAY INTO TUESDAY...TEMPERATURES OVER THE NEXT WEEK WILL BE AT OR ABOVE NORMAL. SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT. MID AND HIGH CLOUDS WILL ADVANCE INTO ILLINOIS TONIGHT AS MID LEVEL WARM ADVECTION AND MOISTURE FLOWS BEGIN TO SATURATE THE LOWER TROPOSPHERE. FORECAST SOUNDINGS ARE INDICATING MOST AREAS WILL REMAIN DRY OVERNIGHT...ALTHOUGH WE CANT RULE OUT SOME LIGHT RAIN SHOWERS FOR OUR FAR WESTERN COUNTIES FROM SCHUYLER TO KNOX LATE TONIGHT. THE GFS IS THE ONLY MODEL TO BRING MUCH IN THE WAY OF MEASURABLE RAIN BEFORE 12Z TO OUR WESTERN COUNTIES...SO WE OPTED TO TREND VERY LOW ON THE POPS TONIGHT. ON SATURDAY...THE PRIMARY FORCING FOR PRECIP WILL REMAIN FOCUSED NORTHWEST OF I-55...WHILE AREAS SOUTHEAST OF I-55 REMAIN MAINLY DRY. WE KEPT LIKELY POPS TOWARD FULTON AND KNOX COUNTIES...WITH CHANCE POPS DOWN TO I-55. SOUTHEAST WINDS WILL BEGIN TO RESPOND TO THE PRESSURE FALLS BY SATURDAY AFTERNOON...WITH WINDS IN THE 20-30 MPH RANGE AT TIMES. THE GUSTY WINDS WILL CONTINUE TO AID THE MOISTURE TRANSPORT IN THE BOUNDARY LAYER SATURDAY NIGHT. WE KEPT CATEGORICAL POPS SAT EVENING AND EXPANDED THEM NEARLY EVERYWHERE AFTER MIDNIGHT. THE BULK OF OUR RAINFALL AMOUNTS LOOK TO BE FOCUSED FROM MIDNIGHT SATURDAY NIGHT THROUGH NOON ON SUNDAY...WITH ELEVATED THUNDERSTORMS EVEN POSSIBLE AT TIMES LATE SAT NIGHT AND SUNDAY MORNING AS THE COLD FRONT MOVES ACROSS THE AREA. WE KEPT THE MENTION OF THUNDER MAINLY CONFINED WEST OF SPI SAT NIGHT AND SOUTH OF LINCOLN ON SUNDAY MORNING. STRONG SOUTH WINDS WILL ACCOMPANY THE RAIN SHOWERS AND STORMS AS THEY PUSH ACROSS THE AREA. WIND GUSTS OVER 30MPH WILL BE POSSIBLE. BY SUNDAY AFTERNOON THE BEST INSTABILITY WILL HAVE SHIFTED EAST INTO INDIANA AS COLDER AIR BEGINS TO INVADE CENTRAL IL ON NORTHWEST WINDS. DOWNWARD ISENTROPIC MOTIONS AND A DRY PUSH ALOFT WILL HELP TO DIMINISH PRECIP SUNDAY NIGHT FROM NW TO SE. WE KEPT CHANCE POPS IN THE SOUTHEAST HALF...WITH THE POTENTIAL FOR SOME LIGHT SNOW NW OF I-70 AFTER MIDNIGHT. LITTLE IN THE WAY OF SNOW ACCUMULATION IS EXPECTED...AS THE WET AND WARM GROUND MELTS MOST OF ANY SNOWFALL. LONG TERM...MONDAY THROUGH FRIDAY. LINGERING LIGHT SNOW OR RAIN ON MONDAY MORNING SHOULD TAPER TO SPRINKLES BY AFTERNOON. WE KEPT SLIGHT CHANCE POPS IN THE SOUTHEAST...BUT MOST PRECIP SHOULD BE TRACE AMOUNTS BY THAT TIME. THE COLDEST TEMPS OF THE NEXT WEEK SHOULD BE ON MONDAY AND MONDAY NIGHT...WITH HIGHS ONLY AROUND 40 AND LOWS IN THE MID 20S. TEMPS WILL BEGIN A WARMING TREND ON TUESDAY WHICH WILL CONTINUE THROUGH THURSDAY WHEN HIGHS RETURN TO THE 50S. A COOL DOWN IS PROJECTED FOR THURSDAY NIGHT INTO FRIDAY AS THE NEXT COLD FRONT MOVES ACROSS THE AREA EITHER EARLY THURSDAY MORNING /GFS/ OR LATE THURSDAY /ECMWF/. STILL THE COLDER AIR WILL NOT PLUNGE VERY FAR SOUTH INTO OUR COUNTIES...SO THE COOL DOWN WILL BE TEMPORARY. PRECIP CHANCES HAVE BEEN KEPT IN THE SLIGHT CHANCE CATEGORY...AND ONLY ON FRIDAY FOR NOW. SHIMON && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
138 PM CST THU MAR 7 2013 .DISCUSSION... 1006 AM CST OTHER THAN A FEW TWEAKS TO HOURLY GRIDS...LITTLE/NO CHANGE TO GOING FORECAST THIS MORNING. THIN BUT PERSISTENT LAYER OF STRATUS/STRATOCU REMAINS ACROSS THE REGION...TRAPPED BENEATH STRONG INVERSION SEEN IN THE 900-925 MB LAYER IN BOTH DVN AND ILX 12Z SOUNDINGS. WHILE SOME CLEARING HAS OCCURRED OVER NORTHERN PARTS OF THE CHICAGO METRO AREA AND LAKE MICHIGAN...CLOUDS ARE ACTUALLY SPREADING BACK NORTH ACROSS EASTERN IA WEST OF THE LOW LEVEL HIGH PRESSURE RIDGE AXIS. DESPITE BEING ABLE TO SEE TERRAIN FEATURES THROUGH THE THIN CLOUD LAYER ON GOES VIS SATELLITE... SUSPECT THAT CLOUDS WILL BE HARD TO ERODE TODAY. OTHER THAN A FEW PEEKS AT SOME BLUE SKY...MAINLY CLOUDY CONDITIONS ARE EXPECTED. DEEP SNOW PACK AND THIN CLOUDY LAYER SHOULD KEEP TEMPS IN CHECK WITHIN THE MID 30S OR SO. RATZER //PREV DISCUSSION... 330 AM CST FORECAST CHALLENGES THIS MORNING INCLUDE CLOUDINESS THROUGH TONIGHT...THEN THE BIG SLOPPY RAINY WET MELT DOWN EXPECTED THIS WEEKEND. STUBBORN STRATUS HAS NOT BUDGED AT ALL OVERNIGHT AND IS CURRENTLY BLANKETING THE ENTIRE CWA. MODEL GUIDANCE IS NOT DOING A GREAT JOB HANDLING CURRENT CONDITIONS WITH REGARDS TO THIS STRATUS DECK WHICH LENDS ITSELF TO A LOWER CONFIDENCE FORECAST TODAY INTO TONIGHT. RAP SEEMS TO HAVE THE BEST HANDLE ON LOW LEVEL RH AND IT SUPPORTS WHAT I WAS THINKING WOULD HAPPEN CONCEPTUALLY WHICH IS EROSION FROM THE EDGES COMMENCING AGAIN AFTER SUNRISE...ESPECIALLY FROM THE SOUTHWEST WHERE SNOW PACK IS LESS OVER CENTRAL ILLINOIS. RIDGE AXIS PASSING BY TODAY WILL THEN TURN LOW LEVEL EASTERLY AND WHERE EVER THE EDGE OF THE STRATUS ENDS UP LATE THIS AFTERNOON COULD SEE IT RE-DEVELOPING/RE-ADVECTING BACK WEST ACROSS THE CWA TONIGHT. HUNCH IS THAT EASTERN CWA COULD STAY PRETTY SOCKED IN TODAY WITH SOME CLEARING WEST THIS AFTERNOON BUT WITH POTENTIAL FOR REDEVELOPMENT OF STRATUS TONIGHT. TRYING TO REFLECT THESE TRENDS IN THE GRIDS IS GOING TO BE A CHALLENGE TO SAY THE LEAST... TEMPS WILL BE HELD DOWN BY CLOUDS AND SNOW COVER TODAY...AND THEN HELD UP TONIGHT WHERE STATUS ENDS UP PARKING. WESTERN CWA STANDS A CHANCE OF SEEING CLEAR SKIES THIS EVENING AND A RAPID TEMP DROP. GIVEN THE LIGHT WINDS THERE IS A POTENTIAL FOR SOME FREEZING GROUND FOG DEVELOPING PRIOR TO THE ARRIVAL OF ANY STRATUS. ONCE AGAIN TONIGHT LOW TEMPERATURE FORECAST IS VERY LOW CONFIDENCE WITH ABOUT A 15-20F RANGE OF POSSIBLE LOWS...ESPECIALLY WESTERN CWA. SAME DEAL FRIDAY...IF STRATUS DECK NEVER CLEARS OUT THEN CLOUDY START WITH POSSIBLE SCATTERING OUT IN THE AFTERNOON WOULD BE EXPECTED WITH COLDER TEMPS. CONVERSELY...SHOULD THE STRATUS BE GONE SUNNY SKIES WITH HIGHER SUN ANGLE MARCH SUN COULD RESULT IN FRIDAY TURNING INTO DAY 1 OF THE GREAT MELT DOWN WITH HIGHS GETTING WELL INTO THE 30S AND MAYBE LOW 40S IN SOUTHERN CWA AND IN MORE URBANIZED AREAS. WEEKEND FORECAST STILL GENERALLY LOOKS ON TRACK...THOUGH MODELS HAVE TRENDED TOWARD A SLIGHTLY WEAKER/LESS PHASED SOLUTION WOULD MEAN A SOMEWHAT LESSER THREAT OF HEAVY RAINFALL. WE ARE STILL PRETTY FAR OUT IN TIME AND WOULD ANTICIPATE MORE CHANGES IN FORECAST GUIDANCE THE NEXT COUPLE DAYS...MOST LIKELY TO SLOW THE SYSTEM DOWN IF ANYTHING...SO NOT GOING TO MAKE ANY BIG CHANGES TO GOING FORECAST FOR THE WEEKEND. EARLY NEXT WEEK THE RUNS DE JOUR OF THE MEDIUM RANGE GUIDANCE LOOKS LESS FOREBODING REGARDING A SNOW SYSTEM WITH A LESS PHASED MORE POSITIVELY TILTED/PROGRESSIVE TROUGH MOVING THROUGH BUT STILL PLENTY OF TIME FOR THAT TO CHANGE SO PROBABLY A LITTLE PREMATURE TO PUT AWAY THE SHOVELS FOR THE YEAR YET. IZZI && .HYDROLOGY... 330 AM CST DEEP WATER LOGGED SNOW PACK BLANKETS THE CWA WITH SNOW WATER EQUIV`S NEAR TO OVER AN INCH OVER NORTHERN HALF OF THE CWA. RISING TEMPS AND DEWPOINTS THIS WEEKEND SHOULD RESULT IN AN INCREASING QUICK MELTING OF THE SNOW PACK...WITH ANY RAIN FALLING ON TOP OF IT SERVING TO FURTHER INCREASE THE CHANCE OF SOME FLOODING PROBLEMS DEVELOPING. CONFIDENCE IN RAINFALL TOTALS THIS WEEKEND NOT OVERLY HIGH...BUT EARLY BALL PARK NUMBERS IN THE HALF INCH TO ONE INCH RANGE LOOK QUITE PLAUSIBLE AND SUFFICIENT FOR SIGNIFICANT RISES ON AREA RIVERS AND POTENTIAL FOR FLOODING. WILL CONTINUE TO HIGHLIGHT THREAT IN THE HWO AND DAY SHIFT MAY NEED TO CONSIDER AN ESF. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * SLIGHT CHANCE FOR VIS RESTRICTIONS IN BR EARLY FRIDAY MORNING. KREIN //DISCUSSION...UPDATED 18Z... MAIN ISSUE FOR THE REMAINDER OF THE AFTERNOON AND INTO THIS EVENING WILL BE CEILINGS. THE LOWER END VFR STRATOCU DECK REMAINS IN PLACE OVER MUCH OF THE AREA...LOWERING TO HIGH END MVFR CIGS WEST OF THE CHICAGO AREA INCLUDING RFD. A CLEARING SLOT HAD PUSHED SOUTH OVER FAR NERN IL THIS MORNING...ALLOWING ORD TO BRIEFLY IMPROVE TO SCT035...BUT THE STRATOCU HAS FILLED BACK TO BKN- OVC035. WHILE THE LATEST VISIBLE SATELLITE IMAGERY INDICATES THAT THE CLOUD IS VERY THIN...WITH SFC FEATURES SHOWING THROUGH THE CLOUD COVER...THE 11-3.9 MICRON IMAGERY MUCH BETTER SHOWS THE EXTENT OF THE CLOUD COVER...WITH LATEST TRENDS INDICATING NO TREND OF CLOUD COVER TO IMPROVE. ALSO...MODEL SOUNDING CONTINUE TO INDICATE A WEAK INVERSION IN PLACE THROUGH THE AFTERNOON AND THIS EVENING...SO DO NOT EXPECT ANY DEEP LAYER MIXING TO HELP BREAK UP THE CLOUD COVER. WITH THE SFC RIDGE MOVING ACROSS THE AREA...EXPECT THAT WINDS WILL BE LGT/VRBL TO CALM THROUGH MUCH OF THE PERIOD...BEFORE BECOMING MORE SELY AND STRENGTHENING TOMORROW MORNING AS THE SFC RIDGE PUSHES TO THE EAST. HAVE SOME CONCERN FOR REDUCED VISBY IN BR/FG OVERNIGHT TONIGHT WITH LIGHT WINDS AND DECREASING CLOUD COVER. HOWEVER...CONFIDENCE IS NOT HIGH IN THE CLOUD COVER TRENDS. ALSO...SFC DEWPOINTS ARE EXPECTED TO REMAIN FAIRLY LOW...SO DO NOT HAVE HIGH ENOUGH CONFIDENCE IN THE POTENTIAL FOR REDUCED VISBY TONIGHT TO INCLUDE IN THE TAFS JUST YET. LOOKING AHEAD TO THIS WEEKEND...LOOKING AT THE POTENTIAL FOR WIDESPREAD FOG DEVELOPMENT AS STRONG MOIST ADVECTION DRIVES DEWPOINTS INTO THE 30S AND EVENTUALLY 40S OVER DEEP SNOW PACK. THIS TYPE OF SETUP HAS THE POTENTIAL FOR PRODUCING WIDESPREAD AND POTENTIALLY DENSE FOG. KREIN //ORD AND MDW CONFIDENCE...UPDATED 20Z... * LOW CONFIDENCE ON TIMING SCATTERING OF THE STRATOCU DECK...AND THE POTENTIAL FOR BR/FG LATE TONIGHT INTO EARLY TOMORROW MORNING. * MEDIUM TO HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. KREIN //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT THROUGH SATURDAY...VFR. SATURDAY NIGHT THROUGH SUNDAY...RAIN/FOG. MONDAY...CHC RAIN/SNOW. TUESDAY THROUGH WEDNESDAY...VFR. BMD && .MARINE... 1245 PM CST SURFACE HIGH PRESSURE RIDGING STRETCHING FROM ONTARIO SOUTH ACROSS WISCONSIN AND ILLINOIS WILL CONTINUE TO DRIFT EAST ACROSS LAKE MICHIGAN THROUGH FRIDAY. DECREASING LIGHT NORTH WINDS WILL BECOME SOUTHEAST ON FRIDAY...INCREASING MODESTLY FRIDAY NIGHT AND BECOMING MORE SOUTHERLY AS LOW PRESSURE DEVELOPS AND DEEPENS ACROSS THE HIGH PLAINS TO THE WEST. LOW PRESSURE WILL LIFT NORTHEAST ACROSS THE CENTRAL PLAINS ON SATURDAY...WITH THE SURFACE PRESSURE GRADIENT ACROSS THE WESTERN LAKES TIGHTENING IN RESPONSE TO THE DEVELOPMENT AND APPROACH OF THE LOW. WITH RELATIVELY MILD SOUTHERLY FLOW ACROSS THE AREA...FORECAST SOUNDINGS INDICATE THAT LOW LEVEL LAPSE RATES WILL NOT BE PARTICULARLY STEEP...AND SUPPORT WINDS INCREASING TO 20-25 KT FOR THE MOST PART SATURDAY AFTERNOON AND NIGHT WITH PERHAPS SOME GUSTS AROUND 30 KT. STRONGER WINDS...GALES IN THE 35-45 KT RANGE...WILL EXIST JUST 1000 FT AGL...THOUGH THE WEAK LAPSE RATES SUGGEST IT MAY BE TOUGH TO MIX THESE WINDS TO THE SURFACE WITH THE AIR BECOMING WARMER THAN THE LAKE SURFACE. THE GENERAL TREND IN FORECAST MODEL GUIDANCE OVER THE PAST FEW RUNS HAS BEEN TO WEAKEN THE LOW AS IT MOVES INTO THE WESTERN LAKES REGION EARLY SUNDAY...WHICH SHOULD ALLOW SOUTH WINDS TO WEAKEN LATE SATURDAY NIGHT OR SUNDAY MORNING AS THE GRADIENT WEAKENS AND BECOMES BAGGY WITH THE SURFACE TROUGH/LOW APPROACH FROM THE WEST/SOUTHWEST. SOUTH WINDS ARE THUS EXPECTED TO DIMINISH AND THEN VEER TO THE NORTH DURING THE DAY SUNDAY AS THE TROUGH/COLD FRONT PASS. NORTH WINDS THEN LOOK TO INCREASE BEHIND THE FRONT...AS THE GRADIENT TIGHTENS AGAIN AHEAD OF HIGH PRESSURE SPREADING ACROSS ONTARIO AND THE UPPER MIDWEST...AND WITH COLDER AIR BEHIND THE FRONT PRODUCING MUCH STEEPER LOW LEVEL LAPSE RATES ALLOWING MIXING OF STRONGER WINDS TO THE SURFACE. NORTH WINDS TO 30 KTS APPEAR TO BE A FAIRLY HIGH PROBABILITY SUNDAY AFTERNOON AND NIGHT...WITH THE POTENTIAL FOR NORTH GALES. WINDS THEN DECREASE MONDAY AS THE SURFACE RIDGE APPROACHES. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1246 PM CST THU MAR 7 2013 .DISCUSSION... 1006 AM CST OTHER THAN A FEW TWEAKS TO HOURLY GRIDS...LITTLE/NO CHANGE TO GOING FORECAST THIS MORNING. THIN BUT PERSISTENT LAYER OF STRATUS/STRATOCU REMAINS ACROSS THE REGION...TRAPPED BENEATH STRONG INVERSION SEEN IN THE 900-925 MB LAYER IN BOTH DVN AND ILX 12Z SOUNDINGS. WHILE SOME CLEARING HAS OCCURRED OVER NORTHERN PARTS OF THE CHICAGO METRO AREA AND LAKE MICHIGAN...CLOUDS ARE ACTUALLY SPREADING BACK NORTH ACROSS EASTERN IA WEST OF THE LOW LEVEL HIGH PRESSURE RIDGE AXIS. DESPITE BEING ABLE TO SEE TERRAIN FEATURES THROUGH THE THIN CLOUD LAYER ON GOES VIS SATELLITE... SUSPECT THAT CLOUDS WILL BE HARD TO ERODE TODAY. OTHER THAN A FEW PEEKS AT SOME BLUE SKY...MAINLY CLOUDY CONDITIONS ARE EXPECTED. DEEP SNOW PACK AND THIN CLOUDY LAYER SHOULD KEEP TEMPS IN CHECK WITHIN THE MID 30S OR SO. RATZER //PREV DISCUSSION... 330 AM CST FORECAST CHALLENGES THIS MORNING INCLUDE CLOUDINESS THROUGH TONIGHT...THEN THE BIG SLOPPY RAINY WET MELT DOWN EXPECTED THIS WEEKEND. STUBBORN STRATUS HAS NOT BUDGED AT ALL OVERNIGHT AND IS CURRENTLY BLANKETING THE ENTIRE CWA. MODEL GUIDANCE IS NOT DOING A GREAT JOB HANDLING CURRENT CONDITIONS WITH REGARDS TO THIS STRATUS DECK WHICH LENDS ITSELF TO A LOWER CONFIDENCE FORECAST TODAY INTO TONIGHT. RAP SEEMS TO HAVE THE BEST HANDLE ON LOW LEVEL RH AND IT SUPPORTS WHAT I WAS THINKING WOULD HAPPEN CONCEPTUALLY WHICH IS EROSION FROM THE EDGES COMMENCING AGAIN AFTER SUNRISE...ESPECIALLY FROM THE SOUTHWEST WHERE SNOW PACK IS LESS OVER CENTRAL ILLINOIS. RIDGE AXIS PASSING BY TODAY WILL THEN TURN LOW LEVEL EASTERLY AND WHERE EVER THE EDGE OF THE STRATUS ENDS UP LATE THIS AFTERNOON COULD SEE IT RE-DEVELOPING/RE-ADVECTING BACK WEST ACROSS THE CWA TONIGHT. HUNCH IS THAT EASTERN CWA COULD STAY PRETTY SOCKED IN TODAY WITH SOME CLEARING WEST THIS AFTERNOON BUT WITH POTENTIAL FOR REDEVELOPMENT OF STRATUS TONIGHT. TRYING TO REFLECT THESE TRENDS IN THE GRIDS IS GOING TO BE A CHALLENGE TO SAY THE LEAST... TEMPS WILL BE HELD DOWN BY CLOUDS AND SNOW COVER TODAY...AND THEN HELD UP TONIGHT WHERE STATUS ENDS UP PARKING. WESTERN CWA STANDS A CHANCE OF SEEING CLEAR SKIES THIS EVENING AND A RAPID TEMP DROP. GIVEN THE LIGHT WINDS THERE IS A POTENTIAL FOR SOME FREEZING GROUND FOG DEVELOPING PRIOR TO THE ARRIVAL OF ANY STRATUS. ONCE AGAIN TONIGHT LOW TEMPERATURE FORECAST IS VERY LOW CONFIDENCE WITH ABOUT A 15-20F RANGE OF POSSIBLE LOWS...ESPECIALLY WESTERN CWA. SAME DEAL FRIDAY...IF STRATUS DECK NEVER CLEARS OUT THEN CLOUDY START WITH POSSIBLE SCATTERING OUT IN THE AFTERNOON WOULD BE EXPECTED WITH COLDER TEMPS. CONVERSELY...SHOULD THE STRATUS BE GONE SUNNY SKIES WITH HIGHER SUN ANGLE MARCH SUN COULD RESULT IN FRIDAY TURNING INTO DAY 1 OF THE GREAT MELT DOWN WITH HIGHS GETTING WELL INTO THE 30S AND MAYBE LOW 40S IN SOUTHERN CWA AND IN MORE URBANIZED AREAS. WEEKEND FORECAST STILL GENERALLY LOOKS ON TRACK...THOUGH MODELS HAVE TRENDED TOWARD A SLIGHTLY WEAKER/LESS PHASED SOLUTION WOULD MEAN A SOMEWHAT LESSER THREAT OF HEAVY RAINFALL. WE ARE STILL PRETTY FAR OUT IN TIME AND WOULD ANTICIPATE MORE CHANGES IN FORECAST GUIDANCE THE NEXT COUPLE DAYS...MOST LIKELY TO SLOW THE SYSTEM DOWN IF ANYTHING...SO NOT GOING TO MAKE ANY BIG CHANGES TO GOING FORECAST FOR THE WEEKEND. EARLY NEXT WEEK THE RUNS DE JOUR OF THE MEDIUM RANGE GUIDANCE LOOKS LESS FOREBODING REGARDING A SNOW SYSTEM WITH A LESS PHASED MORE POSITIVELY TILTED/PROGRESSIVE TROUGH MOVING THROUGH BUT STILL PLENTY OF TIME FOR THAT TO CHANGE SO PROBABLY A LITTLE PREMATURE TO PUT AWAY THE SHOVELS FOR THE YEAR YET. IZZI && .HYDROLOGY... 330 AM CST DEEP WATER LOGGED SNOW PACK BLANKETS THE CWA WITH SNOW WATER EQUIV`S NEAR TO OVER AN INCH OVER NORTHERN HALF OF THE CWA. RISING TEMPS AND DEWPOINTS THIS WEEKEND SHOULD RESULT IN AN INCREASING QUICK MELTING OF THE SNOW PACK...WITH ANY RAIN FALLING ON TOP OF IT SERVING TO FURTHER INCREASE THE CHANCE OF SOME FLOODING PROBLEMS DEVELOPING. CONFIDENCE IN RAINFALL TOTALS THIS WEEKEND NOT OVERLY HIGH...BUT EARLY BALL PARK NUMBERS IN THE HALF INCH TO ONE INCH RANGE LOOK QUITE PLAUSIBLE AND SUFFICIENT FOR SIGNIFICANT RISES ON AREA RIVERS AND POTENTIAL FOR FLOODING. WILL CONTINUE TO HIGHLIGHT THREAT IN THE HWO AND DAY SHIFT MAY NEED TO CONSIDER AN ESF. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * SLIGHT CHANCE FOR VIS RESTRICTIONS IN BR EARLY FRIDAY MORNING. KREIN //DISCUSSION...UPDATED 18Z... MAIN ISSUE FOR THE REMAINDER OF THE AFTERNOON AND INTO THIS EVENING WILL BE CEILINGS. THE LOWER END VFR STRATOCU DECK REMAINS IN PLACE OVER MUCH OF THE AREA...LOWERING TO HIGH END MVFR CIGS WEST OF THE CHICAGO AREA INCLUDING RFD. A CLEARING SLOT HAD PUSHED SOUTH OVER FAR NERN IL THIS MORNING...ALLOWING ORD TO BRIEFLY IMPROVE TO SCT035...BUT THE STRATOCU HAS FILLED BACK TO BKN- OVC035. WHILE THE LATEST VISIBLE SATELLITE IMAGERY INDICATES THAT THE CLOUD IS VERY THIN...WITH SFC FEATURES SHOWING THROUGH THE CLOUD COVER...THE 11-3.9 MICRON IMAGERY MUCH BETTER SHOWS THE EXTENT OF THE CLOUD COVER...WITH LATEST TRENDS INDICATING NO TREND OF CLOUD COVER TO IMPROVE. ALSO...MODEL SOUNDING CONTINUE TO INDICATE A WEAK INVERSION IN PLACE THROUGH THE AFTERNOON AND THIS EVENING...SO DO NOT EXPECT ANY DEEP LAYER MIXING TO HELP BREAK UP THE CLOUD COVER. WITH THE SFC RIDGE MOVING ACROSS THE AREA...EXPECT THAT WINDS WILL BE LGT/VRBL TO CALM THROUGH MUCH OF THE PERIOD...BEFORE BECOMING MORE SELY AND STRENGTHENING TOMORROW MORNING AS THE SFC RIDGE PUSHES TO THE EAST. HAVE SOME CONCERN FOR REDUCED VISBY IN BR/FG OVERNIGHT TONIGHT WITH LIGHT WINDS AND DECREASING CLOUD COVER. HOWEVER...CONFIDENCE IS NOT HIGH IN THE CLOUD COVER TRENDS. ALSO...SFC DEWPOINTS ARE EXPECTED TO REMAIN FAIRLY LOW...SO DO NOT HAVE HIGH ENOUGH CONFIDENCE IN THE POTENTIAL FOR REDUCED VISBY TONIGHT TO INCLUDE IN THE TAFS JUST YET. LOOKING AHEAD TO THIS WEEKEND...LOOKING AT THE POTENTIAL FOR WIDESPREAD FOG DEVELOPMENT AS STRONG MOIST ADVECTION DRIVES DEWPOINTS INTO THE 30S AND EVENTUALLY 40S OVER DEEP SNOW PACK. THIS TYPE OF SETUP HAS THE POTENTIAL FOR PRODUCING WIDESPREAD AND POTENTIALLY DENSE FOG. KREIN //ORD AND MDW CONFIDENCE...UPDATED 18Z... * LOW CONFIDENCE ON TIMING SCATTERING OF THE STRATOCU DECK...AND THE POTENTIAL FOR BR/FG LATE TONIGHT INTO EARLY TOMORROW MORNING. * MEDIUM TO HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. KREIN //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT THROUGH SATURDAY...VFR. SATURDAY NIGHT THROUGH SUNDAY...RAIN/FOG. MONDAY...CHC RAIN/SNOW. TUESDAY THROUGH WEDNESDAY...VFR. BMD && .MARINE... 1245 PM CST SURFACE HIGH PRESSURE RIDGING STRETCHING FROM ONTARIO SOUTH ACROSS WISCONSIN AND ILLINOIS WILL CONTINUE TO DRIFT EAST ACROSS LAKE MICHIGAN THROUGH FRIDAY. DECREASING LIGHT NORTH WINDS WILL BECOME SOUTHEAST ON FRIDAY...INCREASING MODESTLY FRIDAY NIGHT AND BECOMING MORE SOUTHERLY AS LOW PRESSURE DEVELOPS AND DEEPENS ACROSS THE HIGH PLAINS TO THE WEST. LOW PRESSURE WILL LIFT NORTHEAST ACROSS THE CENTRAL PLAINS ON SATURDAY...WITH THE SURFACE PRESSURE GRADIENT ACROSS THE WESTERN LAKES TIGHTENING IN RESPONSE TO THE DEVELOPMENT AND APPROACH OF THE LOW. WITH RELATIVELY MILD SOUTHERLY FLOW ACROSS THE AREA...FORECAST SOUNDINGS INDICATE THAT LOW LEVEL LAPSE RATES WILL NOT BE PARTICULARLY STEEP...AND SUPPORT WINDS INCREASING TO 20-25 KT FOR THE MOST PART SATURDAY AFTERNOON AND NIGHT WITH PERHAPS SOME GUSTS AROUND 30 KT. STRONGER WINDS...GALES IN THE 35-45 KT RANGE...WILL EXIST JUST 1000 FT AGL...THOUGH THE WEAK LAPSE RATES SUGGEST IT MAY BE TOUGH TO MIX THESE WINDS TO THE SURFACE WITH THE AIR BECOMING WARMER THAN THE LAKE SURFACE. THE GENERAL TREND IN FORECAST MODEL GUIDANCE OVER THE PAST FEW RUNS HAS BEEN TO WEAKEN THE LOW AS IT MOVES INTO THE WESTERN LAKES REGION EARLY SUNDAY...WHICH SHOULD ALLOW SOUTH WINDS TO WEAKEN LATE SATURDAY NIGHT OR SUNDAY MORNING AS THE GRADIENT WEAKENS AND BECOMES BAGGY WITH THE SURFACE TROUGH/LOW APPROACH FROM THE WEST/SOUTHWEST. SOUTH WINDS ARE THUS EXPECTED TO DIMINISH AND THEN VEER TO THE NORTH DURING THE DAY SUNDAY AS THE TROUGH/COLD FRONT PASS. NORTH WINDS THEN LOOK TO INCREASE BEHIND THE FRONT...AS THE GRADIENT TIGHTENS AGAIN AHEAD OF HIGH PRESSURE SPREADING ACROSS ONTARIO AND THE UPPER MIDWEST...AND WITH COLDER AIR BEHIND THE FRONT PRODUCING MUCH STEEPER LOW LEVEL LAPSE RATES ALLOWING MIXING OF STRONGER WINDS TO THE SURFACE. NORTH WINDS TO 30 KTS APPEAR TO BE A FAIRLY HIGH PROBABILITY SUNDAY AFTERNOON AND NIGHT...WITH THE POTENTIAL FOR NORTH GALES. WINDS THEN DECREASE MONDAY AS THE SURFACE RIDGE APPROACHES. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1141 AM CST THU MAR 7 2013 .DISCUSSION... ISSUED 951 AM CST THU MAR 7 2013 CLOUDS CONTINUE TO PLAGUE CENTRAL AND SOUTHEAST ILLINOIS THIS MORNING...THANKS TO MOISTURE TRAPPED BENEATH A STRONG LOW-LEVEL SUBSIDENCE INVERSION. LATEST VISIBLE SATELLITE IMAGERY SHOWS A RATHER THIN OVERCAST ACROSS THE REGION...WITH MAJOR RIVERS DIMLY VISIBLE THROUGH THE CLOUD COVER. GIVEN RELATIVE THINNESS OF CLOUDS AND STRENGTH OF EARLY MARCH SUN...THINK A FEW HOLES WILL BE PUNCHED IN THE OVERCAST AS THE DAY GOES ON. HOWEVER...WITH STRONG INVERSION IN PLACE AND LITTLE OR NO WIND...EXPECT GENERALLY CLOUDY CONDITIONS THROUGH THE DAY. WINDS WILL BECOME LIGHT AND EASTERLY LATER TODAY/TONIGHT...AS SURFACE HIGH SHIFTS INTO THE OHIO RIVER VALLEY. THIS MAY TEND TO ADVECT LOW-LEVEL MOISTURE BACK INTO THE AREA TONIGHT. WHILE 12Z NAM FORECAST SOUNDINGS INDICATE CLEARING BY EVENING...14Z RUC SOUNDINGS MAY HAVE A BETTER HANDLE ON REALITY...INDICATING MOSTLY CLOUDY CONDITIONS PERSISTING THROUGH THE NIGHT. && .AVIATION... ISSUED 1141 AM CST THU MAR 7 2013 CLOUDS CONTINUE TO BLANKET CENTRAL ILLINOIS LATE THIS MORNING...HOWEVER EARLY MARCH SUN IS BEGINNING TO ERODE THE W/SW EDGE OF THE OVERCAST. SINCE CLOUDS ARE RELATIVELY THIN...THINK THIS PROCESS WILL CONTINUE FOR THE NEXT 3 TO 4 HOURS. AS A RESULT...HAVE SCATTERED THE MVFR CEILINGS AT KSPI BY 19Z AND AT KPIA BY 20Z. WILL KEEP AN EYE ON SATELLITE TRENDS FOR POTENTIAL CLEARING FURTHER EASTWARD...BUT FOR NOW HAVE OPTED TO CONTINUE THE CEILINGS AT THE REMAINING TERMINALS THROUGHOUT THE AFTERNOON. ONCE THE SUN SETS AND LOW-LEVEL FLOW TAKES ON A LIGHT EASTERLY COMPONENT...THINK MOISTURE WILL ADVECT BACK WESTWARD...RESULTING IN CLOUDY CONDITIONS THROUGH THE NIGHT. AS SURFACE HIGH PRESSURE SLIDES FURTHER EASTWARD AND WINDS BEGIN TO INCREASE FROM THE SOUTHEAST...SKIES WILL FINALLY CLEAR OUT ACROSS THE BOARD BY FRIDAY MORNING. BARNES && .PREV DISCUSSION... ISSUED 307 AM CST THU MAR 7 2013 EARLY MORNING SURFACE MAP SHOWED HIGH PRESSURE RIDGING RUNNING THE LENGTH OF THE MISSISSIPPI RIVER. RATHER TIGHT INVERSION JUST ABOVE 900 MB HAS PUT THE KIBOSH ON ANY REAL EROSION OF THE LARGE STRATOCUMULUS DECK OVER MUCH OF THE MIDWEST...WITH ONLY AREAS AROUND JACKSONVILLE SEEING ANY SUSTAINED CLEARING AND THAT HAS BEGUN TO FILL IN AS WELL. THE CLOUDS HAVE KEPT TEMPERATURES IN THE 20S...WHICH IS GOOD SINCE CLEAR SKIES OVER THE SUBSTANTIAL SNOW COVER IN THE NORTHERN CWA WOULD HAVE LIKELY RESULTED IN SINGLE DIGITS AND TEENS IN THAT AREA. LOOKING UPSTAIRS...LATEST WATER VAPOR IMAGERY SHOWING SEVERAL CIRCULATIONS IN A BROAD AREA OF 500 MB LOW PRESSURE OVER THE PACIFIC NORTHWEST. DEVELOPMENT OF THIS PARTICULAR FEATURE WILL BE OF INTEREST TO OUR FORECAST FOR THE WEEKEND. SHORT TERM...TODAY THROUGH FRIDAY... FAIRLY QUIET WEATHER EXPECTED IN THE SHORT TERM...AS THE HIGH PUSHES EAST ACROSS THE GREAT LAKES. FORECAST SOUNDINGS SHOW THE INVERSION SLOW TO ERODE THOUGH...SO WILL KEEP THE EASTERN CWA FAIRLY CLOUDY TODAY AND TRY TO MARK SOME CLEARING ACROSS THE WEST BY MIDDAY. MAIN CONCERN WILL BE WITH FOG POTENTIAL TONIGHT ACROSS THE NORTH...WITH WINDS STILL FAIRLY LIGHT AND SOME POTENTIAL FOR SNOW MELT TODAY. SHOULD SKIES STAY CLOUDY...THIS WOULD BE LESS OF A CONCERN. TEMPERATURE-WISE...WILL CONTINUE THE TREND OF KEEPING HIGHS A FEW DEGREES COOLER ACROSS THE NORTH WHERE THE SNOW DEPTH RANGES FROM 5 TO 9 INCHES. HOWEVER...EVEN THESE AREAS MAY CRACK 40 BY FRIDAY... WITH HIGHS 45-50 FURTHER SOUTH. LONG TERM...SATURDAY THROUGH WEDNESDAY... UPPER LOW IN THE PACIFIC NORTHWEST SHOULD BETTER ORGANIZE AS IT DROPS SOUTHWARD ALONG THE CALIFORNIA COAST TONIGHT AND FRIDAY. LATEST MODEL GUIDANCE CONTINUES TO EJECT THIS FEATURE NORTHEAST THIS WEEKEND...AS A DEEPENING SHORTWAVE TRACKS EAST ACROSS THE CANADIAN PRAIRIES. SOME PHASING OF THE TWO FEATURES IS INDICATED LATER THIS WEEKEND OVER THE CENTRAL U.S. AND THIS WILL SIGNIFICANTLY INCREASE PRECIP CHANCES AS THE WEEKEND PROGRESSES. GOOD MOISTURE SURGE SHOULD TAKE PLACE AHEAD OF THIS PHASING... WITH GFS PRECIPITABLE WATER VALUES OF 1.25 INCHES SATURDAY NIGHT NEAR THE 99TH PERCENTILE FOR EARLY MARCH. WOULD NOT BE SURPRISED TO SEE OVER AN INCH OF RAIN IN SOME AREAS SATURDAY NIGHT THROUGH SUNDAY NIGHT. HAVE INTRODUCED CATEGORICAL RAIN CHANCES SATURDAY NIGHT NORTHWEST OF THE ILLINOIS RIVER...AND ALSO ADDED AREAS OF FOG ACROSS THE NORTHERN CWA DUE TO THE HEAVIER RAIN AND RAPID SNOW MELT. SUNDAY WILL START OUT RATHER WET AS WELL. HOWEVER...THE MODELS BEGIN TO DIVERGE IN TERMS OF WHETHER A DRY SLOT MAY SPREAD IN DURING THE DAY. WITH THE DIVERSITY...WILL NOT TRY TO GET TOO CUTE WITH SPLITTING OUT MORNING AND AFTERNOON PERIODS. TEMPERATURES BOTH DAYS SHOULD REACH WELL INTO THE 50S. SUNDAY NIGHT AND MONDAY...THE GFS AND ECMWF MODELS BOTH SHOW THE NORTHERN WAVE EXITING THE AREA...WHILE ANOTHER LOW DEVELOPS OVER THE SOUTHERN PLAINS. THE GFS IS MORE AGGRESSIVE WITH CLOSING THIS LOW OFF AND LIFTING IT NORTHEAST...WHILE THE ECMWF WEAKENS BACK INTO AN OPEN WAVE. LEANING MORE TOWARD THE ECMWF SOLUTION FOR NOW...AND HAVE LIMITED LIKELY POPS SUNDAY NIGHT TO THE SOUTHEAST THIRD OF THE CWA. HAVE KEPT SOME PRECIP CHANCES IN ON MONDAY FOR NOW...BUT CONFIDENCE IS LOW AT THE MOMENT. HAVE LARGELY KEPT THE PRECIP AS RAIN EXCEPT FOR A MIX IN THE NORTHWEST. MODEL AGREEMENT DOES NOT IMPROVE AS THE WEEK PROGRESSES...WITH THE LONGER RANGE SOLUTIONS VARYING WITH THE STRENGTH OF ANOTHER WAVE DROPPING INTO THE GREAT LAKES ON TUESDAY. THE ECMWF SOLUTION WOULD BE MUCH COOLER FOR US WITH SIGNIFICANT RIDGING WEST OF THE ROCKIES. FOR NOW HAVE KEPT TEMPERATURES ABOUT 5 DEGREES BELOW NORMAL FOR THE END OF THE FORECAST PERIOD. GEELHART && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1127 AM CST THU MAR 7 2013 .DISCUSSION... 1006 AM CST OTHER THAN A FEW TWEAKS TO HOURLY GRIDS...LITTLE/NO CHANGE TO GOING FORECAST THIS MORNING. THIN BUT PERSISTENT LAYER OF STRATUS/STRATOCU REMAINS ACROSS THE REGION...TRAPPED BENEATH STRONG INVERSION SEEN IN THE 900-925 MB LAYER IN BOTH DVN AND ILX 12Z SOUNDINGS. WHILE SOME CLEARING HAS OCCURRED OVER NORTHERN PARTS OF THE CHICAGO METRO AREA AND LAKE MICHIGAN...CLOUDS ARE ACTUALLY SPREADING BACK NORTH ACROSS EASTERN IA WEST OF THE LOW LEVEL HIGH PRESSURE RIDGE AXIS. DESPITE BEING ABLE TO SEE TERRAIN FEATURES THROUGH THE THIN CLOUD LAYER ON GOES VIS SATELLITE... SUSPECT THAT CLOUDS WILL BE HARD TO ERODE TODAY. OTHER THAN A FEW PEEKS AT SOME BLUE SKY...MAINLY CLOUDY CONDITIONS ARE EXPECTED. DEEP SNOW PACK AND THIN CLOUDY LAYER SHOULD KEEP TEMPS IN CHECK WITHIN THE MID 30S OR SO. RATZER //PREV DISCUSSION... 330 AM CST FORECAST CHALLENGES THIS MORNING INCLUDE CLOUDINESS THROUGH TONIGHT...THEN THE BIG SLOPPY RAINY WET MELT DOWN EXPECTED THIS WEEKEND. STUBBORN STRATUS HAS NOT BUDGED AT ALL OVERNIGHT AND IS CURRENTLY BLANKETING THE ENTIRE CWA. MODEL GUIDANCE IS NOT DOING A GREAT JOB HANDLING CURRENT CONDITIONS WITH REGARDS TO THIS STRATUS DECK WHICH LENDS ITSELF TO A LOWER CONFIDENCE FORECAST TODAY INTO TONIGHT. RAP SEEMS TO HAVE THE BEST HANDLE ON LOW LEVEL RH AND IT SUPPORTS WHAT I WAS THINKING WOULD HAPPEN CONCEPTUALLY WHICH IS EROSION FROM THE EDGES COMMENCING AGAIN AFTER SUNRISE...ESPECIALLY FROM THE SOUTHWEST WHERE SNOW PACK IS LESS OVER CENTRAL ILLINOIS. RIDGE AXIS PASSING BY TODAY WILL THEN TURN LOW LEVEL EASTERLY AND WHERE EVER THE EDGE OF THE STRATUS ENDS UP LATE THIS AFTERNOON COULD SEE IT RE-DEVELOPING/RE-ADVECTING BACK WEST ACROSS THE CWA TONIGHT. HUNCH IS THAT EASTERN CWA COULD STAY PRETTY SOCKED IN TODAY WITH SOME CLEARING WEST THIS AFTERNOON BUT WITH POTENTIAL FOR REDEVELOPMENT OF STRATUS TONIGHT. TRYING TO REFLECT THESE TRENDS IN THE GRIDS IS GOING TO BE A CHALLENGE TO SAY THE LEAST... TEMPS WILL BE HELD DOWN BY CLOUDS AND SNOW COVER TODAY...AND THEN HELD UP TONIGHT WHERE STATUS ENDS UP PARKING. WESTERN CWA STANDS A CHANCE OF SEEING CLEAR SKIES THIS EVENING AND A RAPID TEMP DROP. GIVEN THE LIGHT WINDS THERE IS A POTENTIAL FOR SOME FREEZING GROUND FOG DEVELOPING PRIOR TO THE ARRIVAL OF ANY STRATUS. ONCE AGAIN TONIGHT LOW TEMPERATURE FORECAST IS VERY LOW CONFIDENCE WITH ABOUT A 15-20F RANGE OF POSSIBLE LOWS...ESPECIALLY WESTERN CWA. SAME DEAL FRIDAY...IF STRATUS DECK NEVER CLEARS OUT THEN CLOUDY START WITH POSSIBLE SCATTERING OUT IN THE AFTERNOON WOULD BE EXPECTED WITH COLDER TEMPS. CONVERSELY...SHOULD THE STRATUS BE GONE SUNNY SKIES WITH HIGHER SUN ANGLE MARCH SUN COULD RESULT IN FRIDAY TURNING INTO DAY 1 OF THE GREAT MELT DOWN WITH HIGHS GETTING WELL INTO THE 30S AND MAYBE LOW 40S IN SOUTHERN CWA AND IN MORE URBANIZED AREAS. WEEKEND FORECAST STILL GENERALLY LOOKS ON TRACK...THOUGH MODELS HAVE TRENDED TOWARD A SLIGHTLY WEAKER/LESS PHASED SOLUTION WOULD MEAN A SOMEWHAT LESSER THREAT OF HEAVY RAINFALL. WE ARE STILL PRETTY FAR OUT IN TIME AND WOULD ANTICIPATE MORE CHANGES IN FORECAST GUIDANCE THE NEXT COUPLE DAYS...MOST LIKELY TO SLOW THE SYSTEM DOWN IF ANYTHING...SO NOT GOING TO MAKE ANY BIG CHANGES TO GOING FORECAST FOR THE WEEKEND. EARLY NEXT WEEK THE RUNS DE JOUR OF THE MEDIUM RANGE GUIDANCE LOOKS LESS FOREBODING REGARDING A SNOW SYSTEM WITH A LESS PHASED MORE POSITIVELY TILTED/PROGRESSIVE TROUGH MOVING THROUGH BUT STILL PLENTY OF TIME FOR THAT TO CHANGE SO PROBABLY A LITTLE PREMATURE TO PUT AWAY THE SHOVELS FOR THE YEAR YET. IZZI && .HYDROLOGY... 330 AM CST DEEP WATER LOGGED SNOW PACK BLANKETS THE CWA WITH SNOW WATER EQUIV`S NEAR TO OVER AN INCH OVER NORTHERN HALF OF THE CWA. RISING TEMPS AND DEWPOINTS THIS WEEKEND SHOULD RESULT IN AN INCREASING QUICK MELTING OF THE SNOW PACK...WITH ANY RAIN FALLING ON TOP OF IT SERVING TO FURTHER INCREASE THE CHANCE OF SOME FLOODING PROBLEMS DEVELOPING. CONFIDENCE IN RAINFALL TOTALS THIS WEEKEND NOT OVERLY HIGH...BUT EARLY BALL PARK NUMBERS IN THE HALF INCH TO ONE INCH RANGE LOOK QUITE PLAUSIBLE AND SUFFICIENT FOR SIGNIFICANT RISES ON AREA RIVERS AND POTENTIAL FOR FLOODING. WILL CONTINUE TO HIGHLIGHT THREAT IN THE HWO AND DAY SHIFT MAY NEED TO CONSIDER AN ESF. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * SLIGHT CHANCE FOR VIS RESTRICTIONS IN BR EARLY FRIDAY MORNING. KREIN //DISCUSSION...UPDATED 18Z... MAIN ISSUE FOR THE REMAINDER OF THE AFTERNOON AND INTO THIS EVENING WILL BE CEILINGS. THE LOWER END VFR STRATOCU DECK REMAINS IN PLACE OVER MUCH OF THE AREA...LOWERING TO HIGH END MVFR CIGS WEST OF THE CHICAGO AREA INCLUDING RFD. A CLEARING SLOT HAD PUSHED SOUTH OVER FAR NERN IL THIS MORNING...ALLOWING ORD TO BRIEFLY IMPROVE TO SCT035...BUT THE STRATOCU HAS FILLED BACK TO BKN- OVC035. WHILE THE LATEST VISIBLE SATELLITE IMAGERY INDICATES THAT THE CLOUD IS VERY THIN...WITH SFC FEATURES SHOWING THROUGH THE CLOUD COVER...THE 11-3.9 MICRON IMAGERY MUCH BETTER SHOWS THE EXTENT OF THE CLOUD COVER...WITH LATEST TRENDS INDICATING NO TREND OF CLOUD COVER TO IMPROVE. ALSO...MODEL SOUNDING CONTINUE TO INDICATE A WEAK INVERSION IN PLACE THROUGH THE AFTERNOON AND THIS EVENING...SO DO NOT EXPECT ANY DEEP LAYER MIXING TO HELP BREAK UP THE CLOUD COVER. WITH THE SFC RIDGE MOVING ACROSS THE AREA...EXPECT THAT WINDS WILL BE LGT/VRBL TO CALM THROUGH MUCH OF THE PERIOD...BEFORE BECOMING MORE SELY AND STRENGTHENING TOMORROW MORNING AS THE SFC RIDGE PUSHES TO THE EAST. HAVE SOME CONCERN FOR REDUCED VISBY IN BR/FG OVERNIGHT TONIGHT WITH LIGHT WINDS AND DECREASING CLOUD COVER. HOWEVER...CONFIDENCE IS NOT HIGH IN THE CLOUD COVER TRENDS. ALSO...SFC DEWPOINTS ARE EXPECTED TO REMAIN FAIRLY LOW...SO DO NOT HAVE HIGH ENOUGH CONFIDENCE IN THE POTENTIAL FOR REDUCED VISBY TONIGHT TO INCLUDE IN THE TAFS JUST YET. LOOKING AHEAD TO THIS WEEKEND...LOOKING AT THE POTENTIAL FOR WIDESPREAD FOG DEVELOPMENT AS STRONG MOIST ADVECTION DRIVES DEWPOINTS INTO THE 30S AND EVENTUALLY 40S OVER DEEP SNOW PACK. THIS TYPE OF SETUP HAS THE POTENTIAL FOR PRODUCING WIDESPREAD AND POTENTIALLY DENSE FOG. KREIN //ORD AND MDW CONFIDENCE...UPDATED 18Z... * LOW CONFIDENCE ON TIMING SCATTERING OF THE STRATOCU DECK...AND THE POTENTIAL FOR BR/FG LATE TONIGHT INTO EARLY TOMORROW MORNING. * MEDIUM TO HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. KREIN //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT THROUGH SATURDAY...VFR. SATURDAY NIGHT THROUGH SUNDAY...RAIN/FOG. MONDAY...CHC RAIN/SNOW. TUESDAY THROUGH WEDNESDAY...VFR. BMD && .MARINE... 311 AM CST MAIN CONCERN THIS FORECAST PACKAGE WILL BE WINDS INCREASING BEHIND AN AREA OF LOW PRESSURE EARLY NEXT WEEK. SHOULD BE A QUIET END OF THE WORK WEEK WITH HIGH PRESSURE BUILDING ACROSS LAKE MICHIGAN TODAY ALLOWING WINDS AND SUBSEQUENT WAVES TO DIMINISH. WILL ALLOW THE SMALL CRAFT ADVISORY TO EXPIRE WITH THE MORNING NSH ISSUANCE. SOUTHERLY WINDS FRESHEN SOME OVER THE WEEKEND AS LOW PRESSURE TAKES SHAPE OVER THE PLAINS...BUT MAIN CONCERN WILL BE BEHIND THE LOW AS EARLY AS SUNDAY NIGHT WHEN NORTHERLY WINDS ARE EXPECTED TO RAMP UP TO AROUND 30 KT. THESE WINDS SHOULD CONTINUE THROUGH THE DAY MONDAY. MODELS ARE STRUGGLING WITH THE DETAILS OF THIS SYSTEM...INCLUDING HOW STRONG AND WELL ORGANIZED IT WILL BECOME...BUT GENERALLY SUGGEST A BROAD TROUGH ACROSS THE AREA WITH TWO DISTINCT WAVES DEVELOPING. DEPENDING ON HOW IT PANS OUT THERE MAY BE SLIGHTLY STRONGER WINDS //LOW END GALES// WITH A BETTER DEVELOPED LOW OR OVERALL WINDS MAY BE SLIGHTLY WEAKER BUT STAY ELEVATED FOR A LONGER TIME PERIOD WITH A LESS ORGANIZED WAVE. WILL HAVE TO MAKE ADJUSTMENTS AS MODELS LOCK ONTO A PARTICULAR SOLUTION IN THE COMING DAYS. EITHER WAY...WINDS SHOULD BEGIN TO TAPER AGAIN MIDWEEK AS ANOTHER RIDGE BEGINS TO BUILD INTO THE WESTERN GREAT LAKES REGION. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1007 AM CST THU MAR 7 2013 .DISCUSSION... 1006 AM CST OTHER THAN A FEW TWEAKS TO HOURLY GRIDS...LITTLE/NO CHANGE TO GOING FORECAST THIS MORNING. THIN BUT PERSISTENT LAYER OF STRATUS/STRATOCU REMAINS ACROSS THE REGION...TRAPPED BENEATH STRONG INVERSION SEEN IN THE 900-925 MB LAYER IN BOTH DVN AND ILX 12Z SOUNDINGS. WHILE SOME CLEARING HAS OCCURRED OVER NORTHERN PARTS OF THE CHICAGO METRO AREA AND LAKE MICHIGAN...CLOUDS ARE ACTUALLY SPREADING BACK NORTH ACROSS EASTERN IA WEST OF THE LOW LEVEL HIGH PRESSURE RIDGE AXIS. DESPITE BEING ABLE TO SEE TERRAIN FEATURES THROUGH THE THIN CLOUD LAYER ON GOES VIS SATELLITE... SUSPECT THAT CLOUDS WILL BE HARD TO ERODE TODAY. OTHER THAN A FEW PEEKS AT SOME BLUE SKY...MAINLY CLOUDY CONDITIONS ARE EXPECTED. DEEP SNOW PACK AND THIN CLOUDY LAYER SHOULD KEEP TEMPS IN CHECK WITHIN THE MID 30S OR SO. RATZER && .PREV DISCUSSION... 330 AM CST FORECAST CHALLENGES THIS MORNING INCLUDE CLOUDINESS THROUGH TONIGHT...THEN THE BIG SLOPPY RAINY WET MELT DOWN EXPECTED THIS WEEKEND. STUBBORN STRATUS HAS NOT BUDGED AT ALL OVERNIGHT AND IS CURRENTLY BLANKETING THE ENTIRE CWA. MODEL GUIDANCE IS NOT DOING A GREAT JOB HANDLING CURRENT CONDITIONS WITH REGARDS TO THIS STRATUS DECK WHICH LENDS ITSELF TO A LOWER CONFIDENCE FORECAST TODAY INTO TONIGHT. RAP SEEMS TO HAVE THE BEST HANDLE ON LOW LEVEL RH AND IT SUPPORTS WHAT I WAS THINKING WOULD HAPPEN CONCEPTUALLY WHICH IS EROSION FROM THE EDGES COMMENCING AGAIN AFTER SUNRISE...ESPECIALLY FROM THE SOUTHWEST WHERE SNOW PACK IS LESS OVER CENTRAL ILLINOIS. RIDGE AXIS PASSING BY TODAY WILL THEN TURN LOW LEVEL EASTERLY AND WHERE EVER THE EDGE OF THE STRATUS ENDS UP LATE THIS AFTERNOON COULD SEE IT RE-DEVELOPING/RE-ADVECTING BACK WEST ACROSS THE CWA TONIGHT. HUNCH IS THAT EASTERN CWA COULD STAY PRETTY SOCKED IN TODAY WITH SOME CLEARING WEST THIS AFTERNOON BUT WITH POTENTIAL FOR REDEVELOPMENT OF STRATUS TONIGHT. TRYING TO REFLECT THESE TRENDS IN THE GRIDS IS GOING TO BE A CHALLENGE TO SAY THE LEAST... TEMPS WILL BE HELD DOWN BY CLOUDS AND SNOW COVER TODAY...AND THEN HELD UP TONIGHT WHERE STATUS ENDS UP PARKING. WESTERN CWA STANDS A CHANCE OF SEEING CLEAR SKIES THIS EVENING AND A RAPID TEMP DROP. GIVEN THE LIGHT WINDS THERE IS A POTENTIAL FOR SOME FREEZING GROUND FOG DEVELOPING PRIOR TO THE ARRIVAL OF ANY STRATUS. ONCE AGAIN TONIGHT LOW TEMPERATURE FORECAST IS VERY LOW CONFIDENCE WITH ABOUT A 15-20F RANGE OF POSSIBLE LOWS...ESPECIALLY WESTERN CWA. SAME DEAL FRIDAY...IF STRATUS DECK NEVER CLEARS OUT THEN CLOUDY START WITH POSSIBLE SCATTERING OUT IN THE AFTERNOON WOULD BE EXPECTED WITH COLDER TEMPS. CONVERSELY...SHOULD THE STRATUS BE GONE SUNNY SKIES WITH HIGHER SUN ANGLE MARCH SUN COULD RESULT IN FRIDAY TURNING INTO DAY 1 OF THE GREAT MELT DOWN WITH HIGHS GETTING WELL INTO THE 30S AND MAYBE LOW 40S IN SOUTHERN CWA AND IN MORE URBANIZED AREAS. WEEKEND FORECAST STILL GENERALLY LOOKS ON TRACK...THOUGH MODELS HAVE TRENDED TOWARD A SLIGHTLY WEAKER/LESS PHASED SOLUTION WOULD MEAN A SOMEWHAT LESSER THREAT OF HEAVY RAINFALL. WE ARE STILL PRETTY FAR OUT IN TIME AND WOULD ANTICIPATE MORE CHANGES IN FORECAST GUIDANCE THE NEXT COUPLE DAYS...MOST LIKELY TO SLOW THE SYSTEM DOWN IF ANYTHING...SO NOT GOING TO MAKE ANY BIG CHANGES TO GOING FORECAST FOR THE WEEKEND. EARLY NEXT WEEK THE RUNS DE JOUR OF THE MEDIUM RANGE GUIDANCE LOOKS LESS FOREBODING REGARDING A SNOW SYSTEM WITH A LESS PHASED MORE POSITIVELY TILTED/PROGRESSIVE TROUGH MOVING THROUGH BUT STILL PLENTY OF TIME FOR THAT TO CHANGE SO PROBABLY A LITTLE PREMATURE TO PUT AWAY THE SHOVELS FOR THE YEAR YET. IZZI && .HYDROLOGY... 330 AM CST DEEP WATER LOGGED SNOW PACK BLANKETS THE CWA WITH SNOW WATER EQUIV`S NEAR TO OVER AN INCH OVER NORTHERN HALF OF THE CWA. RISING TEMPS AND DEWPOINTS THIS WEEKEND SHOULD RESULT IN AN INCREASING QUICK MELTING OF THE SNOW PACK...WITH ANY RAIN FALLING ON TOP OF IT SERVING TO FURTHER INCREASE THE CHANCE OF SOME FLOODING PROBLEMS DEVELOPING. CONFIDENCE IN RAINFALL TOTALS THIS WEEKEND NOT OVERLY HIGH...BUT EARLY BALL PARK NUMBERS IN THE HALF INCH TO ONE INCH RANGE LOOK QUITE PLAUSIBLE AND SUFFICIENT FOR SIGNIFICANT RISES ON AREA RIVERS AND POTENTIAL FOR FLOODING. WILL CONTINUE TO HIGHLIGHT THREAT IN THE HWO AND DAY SHIFT MAY NEED TO CONSIDER AN ESF. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * POTENTIAL FOR FOG FRIDAY MORNING. KREIN //DISCUSSION...UPDATED 12Z... VFR STRATUS DECK REMAINS IN PLACE OVER THE CHICAGO AREA WITH HIGH END MVFR CIGS WEST OF THE CHICAGO AREA INCLUDING RFD. GUIDANCE IS NOT HANDLING THE SITUATION WELL NOR HOW LONG TO HANG ONTO THE CIGS THROUGH THE DAY. HAVE TRENDED SLOWER WITH CLEARING AS COLD BOUNDARY LAYER UNDERNEATH A MODERATE INVERSION MAY KEEP MOISTURE LOCKED IN THROUGH THE DAY. THERE IS SUBTLE COOLING NOTED AT 925MB THIS AFTERNOON WHICH MODEL SOUNDINGS SUGGEST MAY LEAD TO LOWERING MVFR CIGS AROUND 020...HOWEVER THINK THE MODELS ARE LIKELY OVERDOING THE DIURNAL HEATING COMPONENT TODAY AND RESULTANT LAPSE RATES...AND DO NOT HAVE CONFIDENCE IN THIS SCENARIO PANNING OUT. WILL STICK WITH SCT020 IN THE MEANTIME. WINDS ARE EXPECTED TO REMAIN LESS THAN 10 KT THROUGH THE DAY...AND SHOULD GRADUALLY VEER FROM NW THIS MORNING TO EASTERLY OVERNIGHT. IN THE EVENT WE DO CLEAR OUT TODAY...WILL THEN HAVE TO KEEP AN EYE ON THE FOG POTENTIAL. CONCEPTUALLY...LIGHT WINDS CLOSE TO THE RIDGE AXIS...PERHAPS SOME ADDITIONAL BL MOISTURE WITH TEMPS PEAKING ABOVE FREEZING THIS AFTERNOON HELPING TO MELT SOME OF THE SNOW...AND CLEAR SKIES/FRESH SNOW SHOULD ALL LEAD TO STRONG RADIATIONAL COOLING AND ENHANCED FOG POTENTIAL. DENSE FOG WAS OBSERVED OVERNIGHT TO OUR WEST. BUT FOR NOW...BANKING ON CLOUDY SKIES STICKING AROUND TODAY MINIMIZING THE FOG THREAT. LOOKING AHEAD TO THIS WEEKEND...LOOKING AT THE POTENTIAL FOR WIDESPREAD FOG DEVELOPMENT AS STRONG MOIST ADVECTION DRIVES DEWPOINTS INTO THE 30S AND EVENTUALLY 40S OVER DEEP SNOWPACK. THIS TYPE OF SETUP HAS THE POTENTIAL FOR PRODUCING WIDESPREAD AND POTENTIALLY DENSE FOG. BMD //ORD AND MDW CONFIDENCE...UPDATED 16Z... * LOW CONFIDENCE ON TIMING CLEARING OF VFR CIGS...AND RESULTING FOG POTENTIAL OVERNIGHT. * MMEDIUM TO HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. KREIN //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT THROUGH SATURDAY...VFR. SATURDAY NIGHT THROUGH SUNDAY...RAIN/FOG. MONDAY...CHC RAIN/SNOW. TUESDAY THROUGH WEDNESDAY...VFR. BMD && .MARINE... 311 AM CST MAIN CONCERN THIS FORECAST PACKAGE WILL BE WINDS INCREASING BEHIND AN AREA OF LOW PRESSURE EARLY NEXT WEEK. SHOULD BE A QUIET END OF THE WORK WEEK WITH HIGH PRESSURE BUILDING ACROSS LAKE MICHIGAN TODAY ALLOWING WINDS AND SUBSEQUENT WAVES TO DIMINISH. WILL ALLOW THE SMALL CRAFT ADVISORY TO EXPIRE WITH THE MORNING NSH ISSUANCE. SOUTHERLY WINDS FRESHEN SOME OVER THE WEEKEND AS LOW PRESSURE TAKES SHAPE OVER THE PLAINS...BUT MAIN CONCERN WILL BE BEHIND THE LOW AS EARLY AS SUNDAY NIGHT WHEN NORTHERLY WINDS ARE EXPECTED TO RAMP UP TO AROUND 30 KT. THESE WINDS SHOULD CONTINUE THROUGH THE DAY MONDAY. MODELS ARE STRUGGLING WITH THE DETAILS OF THIS SYSTEM...INCLUDING HOW STRONG AND WELL ORGANIZED IT WILL BECOME...BUT GENERALLY SUGGEST A BROAD TROUGH ACROSS THE AREA WITH TWO DISTINCT WAVES DEVELOPING. DEPENDING ON HOW IT PANS OUT THERE MAY BE SLIGHTLY STRONGER WINDS //LOW END GALES// WITH A BETTER DEVELOPED LOW OR OVERALL WINDS MAY BE SLIGHTLY WEAKER BUT STAY ELEVATED FOR A LONGER TIME PERIOD WITH A LESS ORGANIZED WAVE. WILL HAVE TO MAKE ADJUSTMENTS AS MODELS LOCK ONTO A PARTICULAR SOLUTION IN THE COMING DAYS. EITHER WAY...WINDS SHOULD BEGIN TO TAPER AGAIN MIDWEEK AS ANOTHER RIDGE BEGINS TO BUILD INTO THE WESTERN GREAT LAKES REGION. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
951 AM CST THU MAR 7 2013 .DISCUSSION... ISSUED 951 AM CST THU MAR 7 2013 CLOUDS CONTINUE TO PLAGUE CENTRAL AND SOUTHEAST ILLINOIS THIS MORNING...THANKS TO MOISTURE TRAPPED BENEATH A STRONG LOW-LEVEL SUBSIDENCE INVERSION. LATEST VISIBLE SATELLITE IMAGERY SHOWS A RATHER THIN OVERCAST ACROSS THE REGION...WITH MAJOR RIVERS DIMLY VISIBLE THROUGH THE CLOUD COVER. GIVEN RELATIVE THINNESS OF CLOUDS AND STRENGTH OF EARLY MARCH SUN...THINK A FEW HOLES WILL BE PUNCHED IN THE OVERCAST AS THE DAY GOES ON. HOWEVER...WITH STRONG INVERSION IN PLACE AND LITTLE OR NO WIND...EXPECT GENERALLY CLOUDY CONDITIONS THROUGH THE DAY. WINDS WILL BECOME LIGHT AND EASTERLY LATER TODAY/TONIGHT...AS SURFACE HIGH SHIFTS INTO THE OHIO RIVER VALLEY. THIS MAY TEND TO ADVECT LOW-LEVEL MOISTURE BACK INTO THE AREA TONIGHT. WHILE 12Z NAM FORECAST SOUNDINGS INDICATE CLEARING BY EVENING...14Z RUC SOUNDINGS MAY HAVE A BETTER HANDLE ON REALITY...INDICATING MOSTLY CLOUDY CONDITIONS PERSISTING THROUGH THE NIGHT. BARNES && .AVIATION... ISSUED 556 AM CST THU MAR 7 2013 A PESKY AREA OF MVFR STRATUS/STRATO CUMULUS CONTINUES TO PLAGUE THE CENTRAL ILLINOIS TERMINALS. IN FACT...THE AREAL COVERAGE OF THE CLOUDS HAS EXPANDED SOME OVERNIGHT. EXPECT THE EDGES OF THE CLOUDS TO ERODE TODAY...WITH SKIES POSSIBLY SCATTERING OUT BY THIS EVENING. HOWEVER...THERE IS THE POTENTIAL THE THE CLOUDS WILL HANG ON EVEN LONGER AS THERE IS A STRONG LOW LEVEL INVERSION TO TRAP MOISTURE...AND LOW LEVEL WINDS ARE TOO WEAK TO EFFECTIVELY SCOUR THE CLOUDS OUT. IN FACT...THE LOW LEVEL FLOW TURNS EASTERLY TONIGHT AND MAY ACT TO BLOW CLOUDS BACK WEST INTO THE AREA AFTER CLEARING HAS TAKEN PLACE OVERHEAD. BAK && .PREV DISCUSSION... ISSUED 307 AM CST THU MAR 7 2013 EARLY MORNING SURFACE MAP SHOWED HIGH PRESSURE RIDGING RUNNING THE LENGTH OF THE MISSISSIPPI RIVER. RATHER TIGHT INVERSION JUST ABOVE 900 MB HAS PUT THE KIBOSH ON ANY REAL EROSION OF THE LARGE STRATOCUMULUS DECK OVER MUCH OF THE MIDWEST...WITH ONLY AREAS AROUND JACKSONVILLE SEEING ANY SUSTAINED CLEARING AND THAT HAS BEGUN TO FILL IN AS WELL. THE CLOUDS HAVE KEPT TEMPERATURES IN THE 20S...WHICH IS GOOD SINCE CLEAR SKIES OVER THE SUBSTANTIAL SNOW COVER IN THE NORTHERN CWA WOULD HAVE LIKELY RESULTED IN SINGLE DIGITS AND TEENS IN THAT AREA. LOOKING UPSTAIRS...LATEST WATER VAPOR IMAGERY SHOWING SEVERAL CIRCULATIONS IN A BROAD AREA OF 500 MB LOW PRESSURE OVER THE PACIFIC NORTHWEST. DEVELOPMENT OF THIS PARTICULAR FEATURE WILL BE OF INTEREST TO OUR FORECAST FOR THE WEEKEND. SHORT TERM...TODAY THROUGH FRIDAY... FAIRLY QUIET WEATHER EXPECTED IN THE SHORT TERM...AS THE HIGH PUSHES EAST ACROSS THE GREAT LAKES. FORECAST SOUNDINGS SHOW THE INVERSION SLOW TO ERODE THOUGH...SO WILL KEEP THE EASTERN CWA FAIRLY CLOUDY TODAY AND TRY TO MARK SOME CLEARING ACROSS THE WEST BY MIDDAY. MAIN CONCERN WILL BE WITH FOG POTENTIAL TONIGHT ACROSS THE NORTH...WITH WINDS STILL FAIRLY LIGHT AND SOME POTENTIAL FOR SNOW MELT TODAY. SHOULD SKIES STAY CLOUDY...THIS WOULD BE LESS OF A CONCERN. TEMPERATURE-WISE...WILL CONTINUE THE TREND OF KEEPING HIGHS A FEW DEGREES COOLER ACROSS THE NORTH WHERE THE SNOW DEPTH RANGES FROM 5 TO 9 INCHES. HOWEVER...EVEN THESE AREAS MAY CRACK 40 BY FRIDAY... WITH HIGHS 45-50 FURTHER SOUTH. LONG TERM...SATURDAY THROUGH WEDNESDAY... UPPER LOW IN THE PACIFIC NORTHWEST SHOULD BETTER ORGANIZE AS IT DROPS SOUTHWARD ALONG THE CALIFORNIA COAST TONIGHT AND FRIDAY. LATEST MODEL GUIDANCE CONTINUES TO EJECT THIS FEATURE NORTHEAST THIS WEEKEND...AS A DEEPENING SHORTWAVE TRACKS EAST ACROSS THE CANADIAN PRAIRIES. SOME PHASING OF THE TWO FEATURES IS INDICATED LATER THIS WEEKEND OVER THE CENTRAL U.S. AND THIS WILL SIGNIFICANTLY INCREASE PRECIP CHANCES AS THE WEEKEND PROGRESSES. GOOD MOISTURE SURGE SHOULD TAKE PLACE AHEAD OF THIS PHASING... WITH GFS PRECIPITABLE WATER VALUES OF 1.25 INCHES SATURDAY NIGHT NEAR THE 99TH PERCENTILE FOR EARLY MARCH. WOULD NOT BE SURPRISED TO SEE OVER AN INCH OF RAIN IN SOME AREAS SATURDAY NIGHT THROUGH SUNDAY NIGHT. HAVE INTRODUCED CATEGORICAL RAIN CHANCES SATURDAY NIGHT NORTHWEST OF THE ILLINOIS RIVER...AND ALSO ADDED AREAS OF FOG ACROSS THE NORTHERN CWA DUE TO THE HEAVIER RAIN AND RAPID SNOW MELT. SUNDAY WILL START OUT RATHER WET AS WELL. HOWEVER...THE MODELS BEGIN TO DIVERGE IN TERMS OF WHETHER A DRY SLOT MAY SPREAD IN DURING THE DAY. WITH THE DIVERSITY...WILL NOT TRY TO GET TOO CUTE WITH SPLITTING OUT MORNING AND AFTERNOON PERIODS. TEMPERATURES BOTH DAYS SHOULD REACH WELL INTO THE 50S. SUNDAY NIGHT AND MONDAY...THE GFS AND ECMWF MODELS BOTH SHOW THE NORTHERN WAVE EXITING THE AREA...WHILE ANOTHER LOW DEVELOPS OVER THE SOUTHERN PLAINS. THE GFS IS MORE AGGRESSIVE WITH CLOSING THIS LOW OFF AND LIFTING IT NORTHEAST...WHILE THE ECMWF WEAKENS BACK INTO AN OPEN WAVE. LEANING MORE TOWARD THE ECMWF SOLUTION FOR NOW...AND HAVE LIMITED LIKELY POPS SUNDAY NIGHT TO THE SOUTHEAST THIRD OF THE CWA. HAVE KEPT SOME PRECIP CHANCES IN ON MONDAY FOR NOW...BUT CONFIDENCE IS LOW AT THE MOMENT. HAVE LARGELY KEPT THE PRECIP AS RAIN EXCEPT FOR A MIX IN THE NORTHWEST. MODEL AGREEMENT DOES NOT IMPROVE AS THE WEEK PROGRESSES...WITH THE LONGER RANGE SOLUTIONS VARYING WITH THE STRENGTH OF ANOTHER WAVE DROPPING INTO THE GREAT LAKES ON TUESDAY. THE ECMWF SOLUTION WOULD BE MUCH COOLER FOR US WITH SIGNIFICANT RIDGING WEST OF THE ROCKIES. FOR NOW HAVE KEPT TEMPERATURES ABOUT 5 DEGREES BELOW NORMAL FOR THE END OF THE FORECAST PERIOD. GEELHART && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
815 AM CST THU MAR 7 2013 .DISCUSSION... 330 AM CST FORECAST CHALLENGES THIS MORNING INCLUDE CLOUDINESS THROUGH TONIGHT...THEN THE BIG SLOPPY RAINY WET MELT DOWN EXPECTED THIS WEEKEND. STUBBORN STRATUS HAS NOT BUDGED AT ALL OVERNIGHT AND IS CURRENTLY BLANKETING THE ENTIRE CWA. MODEL GUIDANCE IS NOT DOING A GREAT JOB HANDLING CURRENT CONDITIONS WITH REGARDS TO THIS STRATUS DECK WHICH LENDS ITSELF TO A LOWER CONFIDENCE FORECAST TODAY INTO TONIGHT. RAP SEEMS TO HAVE THE BEST HANDLE ON LOW LEVEL RH AND IT SUPPORTS WHAT I WAS THINKING WOULD HAPPEN CONCEPTUALLY WHICH IS EROSION FROM THE EDGES COMMENCING AGAIN AFTER SUNRISE...ESPECIALLY FROM THE SOUTHWEST WHERE SNOW PACK IS LESS OVER CENTRAL ILLINOIS. RIDGE AXIS PASSING BY TODAY WILL THEN TURN LOW LEVEL EASTERLY AND WHERE EVER THE EDGE OF THE STRATUS ENDS UP LATE THIS AFTERNOON COULD SEE IT RE-DEVELOPING/RE-ADVECTING BACK WEST ACROSS THE CWA TONIGHT. HUNCH IS THAT EASTERN CWA COULD STAY PRETTY SOCKED IN TODAY WITH SOME CLEARING WEST THIS AFTERNOON BUT WITH POTENTIAL FOR REDEVELOPMENT OF STRATUS TONIGHT. TRYING TO REFLECT THESE TRENDS IN THE GRIDS IS GOING TO BE A CHALLENGE TO SAY THE LEAST... TEMPS WILL BE HELD DOWN BY CLOUDS AND SNOW COVER TODAY...AND THEN HELD UP TONIGHT WHERE STATUS ENDS UP PARKING. WESTERN CWA STANDS A CHANCE OF SEEING CLEAR SKIES THIS EVENING AND A RAPID TEMP DROP. GIVEN THE LIGHT WINDS THERE IS A POTENTIAL FOR SOME FREEZING GROUND FOG DEVELOPING PRIOR TO THE ARRIVAL OF ANY STRATUS. ONCE AGAIN TONIGHT LOW TEMPERATURE FORECAST IS VERY LOW CONFIDENCE WITH ABOUT A 15-20F RANGE OF POSSIBLE LOWS...ESPECIALLY WESTERN CWA. SAME DEAL FRIDAY...IF STRATUS DECK NEVER CLEARS OUT THEN CLOUDY START WITH POSSIBLE SCATTERING OUT IN THE AFTERNOON WOULD BE EXPECTED WITH COLDER TEMPS. CONVERSELY...SHOULD THE STRATUS BE GONE SUNNY SKIES WITH HIGHER SUN ANGLE MARCH SUN COULD RESULT IN FRIDAY TURNING INTO DAY 1 OF THE GREAT MELT DOWN WITH HIGHS GETTING WELL INTO THE 30S AND MAYBE LOW 40S IN SOUTHERN CWA AND IN MORE URBANIZED AREAS. WEEKEND FORECAST STILL GENERALLY LOOKS ON TRACK...THOUGH MODELS HAVE TRENDED TOWARD A SLIGHTLY WEAKER/LESS PHASED SOLUTION WOULD MEAN A SOMEWHAT LESSER THREAT OF HEAVY RAINFALL. WE ARE STILL PRETTY FAR OUT IN TIME AND WOULD ANTICIPATE MORE CHANGES IN FORECAST GUIDANCE THE NEXT COUPLE DAYS...MOST LIKELY TO SLOW THE SYSTEM DOWN IF ANYTHING...SO NOT GOING TO MAKE ANY BIG CHANGES TO GOING FORECAST FOR THE WEEKEND. EARLY NEXT WEEK THE RUNS DE JOUR OF THE MEDIUM RANGE GUIDANCE LOOKS LESS FOREBODING REGARDING A SNOW SYSTEM WITH A LESS PHASED MORE POSITIVELY TILTED/PROGRESSIVE TROUGH MOVING THROUGH BUT STILL PLENTY OF TIME FOR THAT TO CHANGE SO PROBABLY A LITTLE PREMATURE TO PUT AWAY THE SHOVELS FOR THE YEAR YET. IZZI && .HYDROLOGY... 330 AM CST DEEP WATER LOGGED SNOW PACK BLANKETS THE CWA WITH SNOW WATER EQUIV`S NEAR TO OVER AN INCH OVER NORTHERN HALF OF THE CWA. RISING TEMPS AND DEWPOINTS THIS WEEKEND SHOULD RESULT IN AN INCREASING QUICK MELTING OF THE SNOW PACK...WITH ANY RAIN FALLING ON TOP OF IT SERVING TO FURTHER INCREASE THE CHANCE OF SOME FLOODING PROBLEMS DEVELOPING. CONFIDENCE IN RAINFALL TOTALS THIS WEEKEND NOT OVERLY HIGH...BUT EARLY BALL PARK NUMBERS IN THE HALF INCH TO ONE INCH RANGE LOOK QUITE PLAUSIBLE AND SUFFICIENT FOR SIGNIFICANT RISES ON AREA RIVERS AND POTENTIAL FOR FLOODING. WILL CONTINUE TO HIGHLIGHT THREAT IN THE HWO AND DAY SHIFT MAY NEED TO CONSIDER AN ESF. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * POTENTIAL FOR FOG FRIDAY MORNING. KREIN //DISCUSSION...UPDATED 12Z... VFR STRATUS DECK REMAINS IN PLACE OVER THE CHICAGO AREA WITH HIGH END MVFR CIGS WEST OF THE CHICAGO AREA INCLUDING RFD. GUIDANCE IS NOT HANDLING THE SITUATION WELL NOR HOW LONG TO HANG ONTO THE CIGS THROUGH THE DAY. HAVE TRENDED SLOWER WITH CLEARING AS COLD BOUNDARY LAYER UNDERNEATH A MODERATE INVERSION MAY KEEP MOISTURE LOCKED IN THROUGH THE DAY. THERE IS SUBTLE COOLING NOTED AT 925MB THIS AFTERNOON WHICH MODEL SOUNDINGS SUGGEST MAY LEAD TO LOWERING MVFR CIGS AROUND 020...HOWEVER THINK THE MODELS ARE LIKELY OVERDOING THE DIURNAL HEATING COMPONENT TODAY AND RESULTANT LAPSE RATES...AND DO NOT HAVE CONFIDENCE IN THIS SCENARIO PANNING OUT. WILL STICK WITH SCT020 IN THE MEANTIME. WINDS ARE EXPECTED TO REMAIN LESS THAN 10 KT THROUGH THE DAY...AND SHOULD GRADUALLY VEER FROM NW THIS MORNING TO EASTERLY OVERNIGHT. IN THE EVENT WE DO CLEAR OUT TODAY...WILL THEN HAVE TO KEEP AN EYE ON THE FOG POTENTIAL. CONCEPTUALLY...LIGHT WINDS CLOSE TO THE RIDGE AXIS...PERHAPS SOME ADDITIONAL BL MOISTURE WITH TEMPS PEAKING ABOVE FREEZING THIS AFTERNOON HELPING TO MELT SOME OF THE SNOW...AND CLEAR SKIES/FRESH SNOW SHOULD ALL LEAD TO STRONG RADIATIONAL COOLING AND ENHANCED FOG POTENTIAL. DENSE FOG WAS OBSERVED OVERNIGHT TO OUR WEST. BUT FOR NOW...BANKING ON CLOUDY SKIES STICKING AROUND TODAY MINIMIZING THE FOG THREAT. LOOKING AHEAD TO THIS WEEKEND...LOOKING AT THE POTENTIAL FOR WIDESPREAD FOG DEVELOPMENT AS STRONG MOIST ADVECTION DRIVES DEWPOINTS INTO THE 30S AND EVENTUALLY 40S OVER DEEP SNOWPACK. THIS TYPE OF SETUP HAS THE POTENTIAL FOR PRODUCING WIDESPREAD AND POTENTIALLY DENSE FOG. BMD //ORD AND MDW CONFIDENCE...UPDATED 14Z... * LOW CONFIDENCE ON TIMING CLEARING OF VFR CIGS...AND RESULTING FOG POTENTIAL OVERNIGHT. * MMEDIUM TO HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. KREIN //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT THROUGH SATURDAY...VFR. SATURDAY NIGHT THROUGH SUNDAY...RAIN/FOG. MONDAY...CHC RAIN/SNOW. TUESDAY THROUGH WEDNESDAY...VFR. BMD && .MARINE... 311 AM CST MAIN CONCERN THIS FORECAST PACKAGE WILL BE WINDS INCREASING BEHIND AN AREA OF LOW PRESSURE EARLY NEXT WEEK. SHOULD BE A QUIET END OF THE WORK WEEK WITH HIGH PRESSURE BUILDING ACROSS LAKE MICHIGAN TODAY ALLOWING WINDS AND SUBSEQUENT WAVES TO DIMINISH. WILL ALLOW THE SMALL CRAFT ADVISORY TO EXPIRE WITH THE MORNING NSH ISSUANCE. SOUTHERLY WINDS FRESHEN SOME OVER THE WEEKEND AS LOW PRESSURE TAKES SHAPE OVER THE PLAINS...BUT MAIN CONCERN WILL BE BEHIND THE LOW AS EARLY AS SUNDAY NIGHT WHEN NORTHERLY WINDS ARE EXPECTED TO RAMP UP TO AROUND 30 KT. THESE WINDS SHOULD CONTINUE THROUGH THE DAY MONDAY. MODELS ARE STRUGGLING WITH THE DETAILS OF THIS SYSTEM...INCLUDING HOW STRONG AND WELL ORGANIZED IT WILL BECOME...BUT GENERALLY SUGGEST A BROAD TROUGH ACROSS THE AREA WITH TWO DISTINCT WAVES DEVELOPING. DEPENDING ON HOW IT PANS OUT THERE MAY BE SLIGHTLY STRONGER WINDS //LOW END GALES// WITH A BETTER DEVELOPED LOW OR OVERALL WINDS MAY BE SLIGHTLY WEAKER BUT STAY ELEVATED FOR A LONGER TIME PERIOD WITH A LESS ORGANIZED WAVE. WILL HAVE TO MAKE ADJUSTMENTS AS MODELS LOCK ONTO A PARTICULAR SOLUTION IN THE COMING DAYS. EITHER WAY...WINDS SHOULD BEGIN TO TAPER AGAIN MIDWEEK AS ANOTHER RIDGE BEGINS TO BUILD INTO THE WESTERN GREAT LAKES REGION. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
529 AM CST THU MAR 7 2013 .DISCUSSION... 330 AM CST FORECAST CHALLENGES THIS MORNING INCLUDE CLOUDINESS THROUGH TONIGHT...THEN THE BIG SLOPPY RAINY WET MELT DOWN EXPECTED THIS WEEKEND. STUBBORN STRATUS HAS NOT BUDGED AT ALL OVERNIGHT AND IS CURRENTLY BLANKETING THE ENTIRE CWA. MODEL GUIDANCE IS NOT DOING A GREAT JOB HANDLING CURRENT CONDITIONS WITH REGARDS TO THIS STRATUS DECK WHICH LENDS ITSELF TO A LOWER CONFIDENCE FORECAST TODAY INTO TONIGHT. RAP SEEMS TO HAVE THE BEST HANDLE ON LOW LEVEL RH AND IT SUPPORTS WHAT I WAS THINKING WOULD HAPPEN CONCEPTUALLY WHICH IS EROSION FROM THE EDGES COMMENCING AGAIN AFTER SUNRISE...ESPECIALLY FROM THE SOUTHWEST WHERE SNOW PACK IS LESS OVER CENTRAL ILLINOIS. RIDGE AXIS PASSING BY TODAY WILL THEN TURN LOW LEVEL EASTERLY AND WHERE EVER THE EDGE OF THE STRATUS ENDS UP LATE THIS AFTERNOON COULD SEE IT RE-DEVELOPING/RE-ADVECTING BACK WEST ACROSS THE CWA TONIGHT. HUNCH IS THAT EASTERN CWA COULD STAY PRETTY SOCKED IN TODAY WITH SOME CLEARING WEST THIS AFTERNOON BUT WITH POTENTIAL FOR REDEVELOPMENT OF STRATUS TONIGHT. TRYING TO REFLECT THESE TRENDS IN THE GRIDS IS GOING TO BE A CHALLENGE TO SAY THE LEAST... TEMPS WILL BE HELD DOWN BY CLOUDS AND SNOW COVER TODAY...AND THEN HELD UP TONIGHT WHERE STATUS ENDS UP PARKING. WESTERN CWA STANDS A CHANCE OF SEEING CLEAR SKIES THIS EVENING AND A RAPID TEMP DROP. GIVEN THE LIGHT WINDS THERE IS A POTENTIAL FOR SOME FREEZING GROUND FOG DEVELOPING PRIOR TO THE ARRIVAL OF ANY STRATUS. ONCE AGAIN TONIGHT LOW TEMPERATURE FORECAST IS VERY LOW CONFIDENCE WITH ABOUT A 15-20F RANGE OF POSSIBLE LOWS...ESPECIALLY WESTERN CWA. SAME DEAL FRIDAY...IF STRATUS DECK NEVER CLEARS OUT THEN CLOUDY START WITH POSSIBLE SCATTERING OUT IN THE AFTERNOON WOULD BE EXPECTED WITH COLDER TEMPS. CONVERSELY...SHOULD THE STRATUS BE GONE SUNNY SKIES WITH HIGHER SUN ANGLE MARCH SUN COULD RESULT IN FRIDAY TURNING INTO DAY 1 OF THE GREAT MELT DOWN WITH HIGHS GETTING WELL INTO THE 30S AND MAYBE LOW 40S IN SOUTHERN CWA AND IN MORE URBANIZED AREAS. WEEKEND FORECAST STILL GENERALLY LOOKS ON TRACK...THOUGH MODELS HAVE TRENDED TOWARD A SLIGHTLY WEAKER/LESS PHASED SOLUTION WOULD MEAN A SOMEWHAT LESSER THREAT OF HEAVY RAINFALL. WE ARE STILL PRETTY FAR OUT IN TIME AND WOULD ANTICIPATE MORE CHANGES IN FORECAST GUIDANCE THE NEXT COUPLE DAYS...MOST LIKELY TO SLOW THE SYSTEM DOWN IF ANYTHING...SO NOT GOING TO MAKE ANY BIG CHANGES TO GOING FORECAST FOR THE WEEKEND. EARLY NEXT WEEK THE RUNS DE JOUR OF THE MEDIUM RANGE GUIDANCE LOOKS LESS FOREBODING REGARDING A SNOW SYSTEM WITH A LESS PHASED MORE POSITIVELY TILTED/PROGRESSIVE TROUGH MOVING THROUGH BUT STILL PLENTY OF TIME FOR THAT TO CHANGE SO PROBABLY A LITTLE PREMATURE TO PUT AWAY THE SHOVELS FOR THE YEAR YET. IZZI && .HYDROLOGY... 330 AM CST DEEP WATER LOGGED SNOW PACK BLANKETS THE CWA WITH SNOW WATER EQUIV`S NEAR TO OVER AN INCH OVER NORTHERN HALF OF THE CWA. RISING TEMPS AND DEWPOINTS THIS WEEKEND SHOULD RESULT IN AN INCREASING QUICK MELTING OF THE SNOW PACK...WITH ANY RAIN FALLING ON TOP OF IT SERVING TO FURTHER INCREASE THE CHANCE OF SOME FLOODING PROBLEMS DEVELOPING. CONFIDENCE IN RAINFALL TOTALS THIS WEEKEND NOT OVERLY HIGH...BUT EARLY BALL PARK NUMBERS IN THE HALF INCH TO ONE INCH RANGE LOOK QUITE PLAUSIBLE AND SUFFICIENT FOR SIGNIFICANT RISES ON AREA RIVERS AND POTENTIAL FOR FLOODING. WILL CONTINUE TO HIGHLIGHT THREAT IN THE HWO AND DAY SHIFT MAY NEED TO CONSIDER AN ESF. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 12Z... * POTENTIAL FOR MVFR CIGS THURSDAY AFTERNOON. * POTENTIAL FOR FOG FRIDAY MORNING. BMD //DISCUSSION...UPDATED 12Z... VFR STRATUS DECK REMAINS IN PLACE OVER THE CHICAGO AREA WITH HIGH END MVFR CIGS WEST OF THE CHICAGO AREA INCLUDING RFD. GUIDANCE IS NOT HANDLING THE SITUATION WELL NOR HOW LONG TO HANG ONTO THE CIGS THROUGH THE DAY. HAVE TRENDED SLOWER WITH CLEARING AS COLD BOUNDARY LAYER UNDERNEATH A MODERATE INVERSION MAY KEEP MOISTURE LOCKED IN THROUGH THE DAY. THERE IS SUBTLE COOLING NOTED AT 925MB THIS AFTERNOON WHICH MODEL SOUNDINGS SUGGEST MAY LEAD TO LOWERING MVFR CIGS AROUND 020...HOWEVER THINK THE MODELS ARE LIKELY OVERDOING THE DIURNAL HEATING COMPONENT TODAY AND RESULTANT LAPSE RATES...AND DO NOT HAVE CONFIDENCE IN THIS SCENARIO PANNING OUT. WILL STICK WITH SCT020 IN THE MEANTIME. WINDS ARE EXPECTED TO REMAIN LESS THAN 10 KT THROUGH THE DAY...AND SHOULD GRADUALLY VEER FROM NW THIS MORNING TO EASTERLY OVERNIGHT. IN THE EVENT WE DO CLEAR OUT TODAY...WILL THEN HAVE TO KEEP AN EYE ON THE FOG POTENTIAL. CONCEPTUALLY...LIGHT WINDS CLOSE TO THE RIDGE AXIS...PERHAPS SOME ADDITIONAL BL MOISTURE WITH TEMPS PEAKING ABOVE FREEZING THIS AFTERNOON HELPING TO MELT SOME OF THE SNOW...AND CLEAR SKIES/FRESH SNOW SHOULD ALL LEAD TO STRONG RADIATIONAL COOLING AND ENHANCED FOG POTENTIAL. DENSE FOG WAS OBSERVED OVERNIGHT TO OUR WEST. BUT FOR NOW...BANKING ON CLOUDY SKIES STICKING AROUND TODAY MINIMIZING THE FOG THREAT. LOOKING AHEAD TO THIS WEEKEND...LOOKING AT THE POTENTIAL FOR WIDESPREAD FOG DEVELOPMENT AS STRONG MOIST ADVECTION DRIVES DEWPOINTS INTO THE 30S AND EVENTUALLY 40S OVER DEEP SNOWPACK. THIS TYPE OF SETUP HAS THE POTENTIAL FOR PRODUCING WIDESPREAD AND POTENTIALLY DENSE FOG. BMD //ORD AND MDW CONFIDENCE...UPDATED 12Z... * LOW CONFIDENCE IN MVFR CIGS THURSDAY AFTERNOON. * LOW CONFIDENCE ON TIMING CLEARING OF VFR CIGS...AND RESULTING FOG POTENTIAL OVERNIGHT. BMD //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT THROUGH SATURDAY...VFR. SATURDAY NIGHT THROUGH SUNDAY...RAIN/FOG. MONDAY...CHC RAIN/SNOW. TUESDAY THROUGH WEDNESDAY...VFR. BMD && .MARINE... 311 AM CST MAIN CONCERN THIS FORECAST PACKAGE WILL BE WINDS INCREASING BEHIND AN AREA OF LOW PRESSURE EARLY NEXT WEEK. SHOULD BE A QUIET END OF THE WORK WEEK WITH HIGH PRESSURE BUILDING ACROSS LAKE MICHIGAN TODAY ALLOWING WINDS AND SUBSEQUENT WAVES TO DIMINISH. WILL ALLOW THE SMALL CRAFT ADVISORY TO EXPIRE WITH THE MORNING NSH ISSUANCE. SOUTHERLY WINDS FRESHEN SOME OVER THE WEEKEND AS LOW PRESSURE TAKES SHAPE OVER THE PLAINS...BUT MAIN CONCERN WILL BE BEHIND THE LOW AS EARLY AS SUNDAY NIGHT WHEN NORTHERLY WINDS ARE EXPECTED TO RAMP UP TO AROUND 30 KT. THESE WINDS SHOULD CONTINUE THROUGH THE DAY MONDAY. MODELS ARE STRUGGLING WITH THE DETAILS OF THIS SYSTEM...INCLUDING HOW STRONG AND WELL ORGANIZED IT WILL BECOME...BUT GENERALLY SUGGEST A BROAD TROUGH ACROSS THE AREA WITH TWO DISTINCT WAVES DEVELOPING. DEPENDING ON HOW IT PANS OUT THERE MAY BE SLIGHTLY STRONGER WINDS //LOW END GALES// WITH A BETTER DEVELOPED LOW OR OVERALL WINDS MAY BE SLIGHTLY WEAKER BUT STAY ELEVATED FOR A LONGER TIME PERIOD WITH A LESS ORGANIZED WAVE. WILL HAVE TO MAKE ADJUSTMENTS AS MODELS LOCK ONTO A PARTICULAR SOLUTION IN THE COMING DAYS. EITHER WAY...WINDS SHOULD BEGIN TO TAPER AGAIN MIDWEEK AS ANOTHER RIDGE BEGINS TO BUILD INTO THE WESTERN GREAT LAKES REGION. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
330 AM CST THU MAR 7 2013 .DISCUSSION... 330 AM CST FORECAST CHALLENGES THIS MORNING INCLUDE CLOUDINESS THROUGH TONIGHT...THEN THE BIG SLOPPY RAINY WET MELT DOWN EXPECTED THIS WEEKEND. STUBBORN STRATUS HAS NOT BUDGED AT ALL OVERNIGHT AND IS CURRENTLY BLANKETING THE ENTIRE CWA. MODEL GUIDANCE IS NOT DOING A GREAT JOB HANDLING CURRENT CONDITIONS WITH REGARDS TO THIS STRATUS DECK WHICH LENDS ITSELF TO A LOWER CONFIDENCE FORECAST TODAY INTO TONIGHT. RAP SEEMS TO HAVE THE BEST HANDLE ON LOW LEVEL RH AND IT SUPPORTS WHAT I WAS THINKING WOULD HAPPEN CONCEPTUALLY WHICH IS EROSION FROM THE EDGES COMMENCING AGAIN AFTER SUNRISE...ESPECIALLY FROM THE SOUTHWEST WHERE SNOW PACK IS LESS OVER CENTRAL ILLINOIS. RIDGE AXIS PASSING BY TODAY WILL THEN TURN LOW LEVEL EASTERLY AND WHERE EVER THE EDGE OF THE STRATUS ENDS UP LATE THIS AFTERNOON COULD SEE IT RE-DEVELOPING/RE-ADVECTING BACK WEST ACROSS THE CWA TONIGHT. HUNCH IS THAT EASTERN CWA COULD STAY PRETTY SOCKED IN TODAY WITH SOME CLEARING WEST THIS AFTERNOON BUT WITH POTENTIAL FOR REDEVELOPMENT OF STRATUS TONIGHT. TRYING TO REFLECT THESE TRENDS IN THE GRIDS IS GOING TO BE A CHALLENGE TO SAY THE LEAST... TEMPS WILL BE HELD DOWN BY CLOUDS AND SNOW COVER TODAY...AND THEN HELD UP TONIGHT WHERE STATUS ENDS UP PARKING. WESTERN CWA STANDS A CHANCE OF SEEING CLEAR SKIES THIS EVENING AND A RAPID TEMP DROP. GIVEN THE LIGHT WINDS THERE IS A POTENTIAL FOR SOME FREEZING GROUND FOG DEVELOPING PRIOR TO THE ARRIVAL OF ANY STRATUS. ONCE AGAIN TONIGHT LOW TEMPERATURE FORECAST IS VERY LOW CONFIDENCE WITH ABOUT A 15-20F RANGE OF POSSIBLE LOWS...ESPECIALLY WESTERN CWA. SAME DEAL FRIDAY...IF STRATUS DECK NEVER CLEARS OUT THEN CLOUDY START WITH POSSIBLE SCATTERING OUT IN THE AFTERNOON WOULD BE EXPECTED WITH COLDER TEMPS. CONVERSELY...SHOULD THE STRATUS BE GONE SUNNY SKIES WITH HIGHER SUN ANGLE MARCH SUN COULD RESULT IN FRIDAY TURNING INTO DAY 1 OF THE GREAT MELT DOWN WITH HIGHS GETTING WELL INTO THE 30S AND MAYBE LOW 40S IN SOUTHERN CWA AND IN MORE URBANIZED AREAS. WEEKEND FORECAST STILL GENERALLY LOOKS ON TRACK...THOUGH MODELS HAVE TRENDED TOWARD A SLIGHTLY WEAKER/LESS PHASED SOLUTION WOULD MEAN A SOMEWHAT LESSER THREAT OF HEAVY RAINFALL. WE ARE STILL PRETTY FAR OUT IN TIME AND WOULD ANTICIPATE MORE CHANGES IN FORECAST GUIDANCE THE NEXT COUPLE DAYS...MOST LIKELY TO SLOW THE SYSTEM DOWN IF ANYTHING...SO NOT GOING TO MAKE ANY BIG CHANGES TO GOING FORECAST FOR THE WEEKEND. EARLY NEXT WEEK THE RUNS DE JOUR OF THE MEDIUM RANGE GUIDANCE LOOKS LESS FOREBODING REGARDING A SNOW SYSTEM WITH A LESS PHASED MORE POSITIVELY TILTED/PROGRESSIVE TROUGH MOVING THROUGH BUT STILL PLENTY OF TIME FOR THAT TO CHANGE SO PROBABLY A LITTLE PREMATURE TO PUT AWAY THE SHOVELS FOR THE YEAR YET. IZZI && .HYDROLOGY... 330 AM CST DEEP WATER LOGGED SNOW PACK BLANKETS THE CWA WITH SNOW WATER EQUIV`S NEAR TO OVER AN INCH OVER NORTHERN HALF OF THE CWA. RISING TEMPS AND DEWPOINTS THIS WEEKEND SHOULD RESULT IN AN INCREASING QUICK MELTING OF THE SNOW PACK...WITH ANY RAIN FALLING ON TOP OF IT SERVING TO FURTHER INCREASE THE CHANCE OF SOME FLOODING PROBLEMS DEVELOPING. CONFIDENCE IN RAINFALL TOTALS THIS WEEKEND NOT OVERLY HIGH...BUT EARLY BALL PARK NUMBERS IN THE HALF INCH TO ONE INCH RANGE LOOK QUITE PLAUSIBLE AND SUFFICIENT FOR SIGNIFICANT RISES ON AREA RIVERS AND POTENTIAL FOR FLOODING. WILL CONTINUE TO HIGHLIGHT THREAT IN THE HWO AND DAY SHIFT MAY NEED TO CONSIDER AN ESF. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * POTENTIAL FOR MVFR CIGS THURSDAY AFTERNOON. BMD //DISCUSSION...UPDATED 06Z... SHOULD BE A FAIRLY QUIET TAF PERIOD AS HIGH PRESSURE BUILDS ACROSS THE AREA. RIDGE AXIS IS CENTERED ALONG THE MISSISSIPPI VALLEY LATE THIS EVENING AND WILL SLOWLY SLIDE EAST THROUGH THE PERIOD. VFR STRATUS DECK REMAINS IN PLACE ACROSS MOST OF NORTHERN ILLINOIS AND SUSPECT WE WILL REMAIN LOCKED IN AS THERE IS NO SIGN OF THE BACK EDGE ERODING SINCE SUNSET. GIVEN THE LATEST THOUGHTS ON STRATUS REMAINING...REMOVED MENTION OF FOG FOR RFD. WILL HAVE TO MONITOR THIS CLOSELY THOUGH AS DENSE FOG IS ALREADY FORMING WHERE SKIES HAVE CLEARED OVER EASTERN IOWA. EXPECT THE STRATUS TO BEGIN ERODING FROM THE WEST IN EARNEST AFTER DAYBREAK THURSDAY. ONCE WE GET UNDER MARCH SUNSHINE...EXPECT SURFACE TEMPS TO WARM TO AROUND THE FREEZING MARK WITH STEEP LOW LEVEL LAPSE RATES DEVELOPING. MODEL SOUNDINGS SHOW POTENTIAL TO DEVELOP SOME MVFR CU/CASCU TUESDAY AFTERNOON...BUT SIGNAL IS MIXED SO FOR NOW JUST INTRODUCED A SCT020 DECK. WINDS SHOULD REMAIN RELATIVELY LIGHT...LESS THAN 10 KT THROUGH THE PERIOD...TRENDING TO THE EAST THURSDAY EVENING BEHIND THE RIDGE AXIS. BMD //ORD AND MDW CONFIDENCE...UPDATED 09Z... * LOW CONFIDENCE IN MVFR CIGS THURSDAY AFTERNOON. * HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. BMD //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z THURSDAY...UPDATED 00Z... THURSDAY NIGHT THROUGH FRIDAY...VFR. SATURDAY THROUGH SUNDAY...CHC RAIN. SUNDAY...RAIN...MVFR. SUNDAY NIGHT...RAIN AND SNOW...IFR LIKELY. MONDAY...RAIN...MVFR LIKELY. TUESDAY...VFR. DZ && .MARINE... 311 AM CST MAIN CONCERN THIS FORECAST PACKAGE WILL BE WINDS INCREASING BEHIND AN AREA OF LOW PRESSURE EARLY NEXT WEEK. SHOULD BE A QUIET END OF THE WORK WEEK WITH HIGH PRESSURE BUILDING ACROSS LAKE MICHIGAN TODAY ALLOWING WINDS AND SUBSEQUENT WAVES TO DIMINISH. WILL ALLOW THE SMALL CRAFT ADVISORY TO EXPIRE WITH THE MORNING NSH ISSUANCE. SOUTHERLY WINDS FRESHEN SOME OVER THE WEEKEND AS LOW PRESSURE TAKES SHAPE OVER THE PLAINS...BUT MAIN CONCERN WILL BE BEHIND THE LOW AS EARLY AS SUNDAY NIGHT WHEN NORTHERLY WINDS ARE EXPECTED TO RAMP UP TO AROUND 30 KT. THESE WINDS SHOULD CONTINUE THROUGH THE DAY MONDAY. MODELS ARE STRUGGLING WITH THE DETAILS OF THIS SYSTEM...INCLUDING HOW STRONG AND WELL ORGANIZED IT WILL BECOME...BUT GENERALLY SUGGEST A BROAD TROUGH ACROSS THE AREA WITH TWO DISTINCT WAVES DEVELOPING. DEPENDING ON HOW IT PANS OUT THERE MAY BE SLIGHTLY STRONGER WINDS //LOW END GALES// WITH A BETTER DEVELOPED LOW OR OVERALL WINDS MAY BE SLIGHTLY WEAKER BUT STAY ELEVATED FOR A LONGER TIME PERIOD WITH A LESS ORGANIZED WAVE. WILL HAVE TO MAKE ADJUSTMENTS AS MODELS LOCK ONTO A PARTICULAR SOLUTION IN THE COMING DAYS. EITHER WAY...WINDS SHOULD BEGIN TO TAPER AGAIN MIDWEEK AS ANOTHER RIDGE BEGINS TO BUILD INTO THE WESTERN GREAT LAKES REGION. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
307 AM CST THU MAR 7 2013 .DISCUSSION... ISSUED 307 AM CST THU MAR 7 2013 EARLY MORNING SURFACE MAP SHOWED HIGH PRESSURE RIDGING RUNNING THE LENGTH OF THE MISSISSIPPI RIVER. RATHER TIGHT INVERSION JUST ABOVE 900 MB HAS PUT THE KIBOSH ON ANY REAL EROSION OF THE LARGE STRATOCUMULUS DECK OVER MUCH OF THE MIDWEST...WITH ONLY AREAS AROUND JACKSONVILLE SEEING ANY SUSTAINED CLEARING AND THAT HAS BEGUN TO FILL IN AS WELL. THE CLOUDS HAVE KEPT TEMPERATURES IN THE 20S...WHICH IS GOOD SINCE CLEAR SKIES OVER THE SUBSTANTIAL SNOW COVER IN THE NORTHERN CWA WOULD HAVE LIKELY RESULTED IN SINGLE DIGITS AND TEENS IN THAT AREA. LOOKING UPSTAIRS...LATEST WATER VAPOR IMAGERY SHOWING SEVERAL CIRCULATIONS IN A BROAD AREA OF 500 MB LOW PRESSURE OVER THE PACIFIC NORTHWEST. DEVELOPMENT OF THIS PARTICULAR FEATURE WILL BE OF INTEREST TO OUR FORECAST FOR THE WEEKEND. SHORT TERM...TODAY THROUGH FRIDAY... FAIRLY QUIET WEATHER EXPECTED IN THE SHORT TERM...AS THE HIGH PUSHES EAST ACROSS THE GREAT LAKES. FORECAST SOUNDINGS SHOW THE INVERSION SLOW TO ERODE THOUGH...SO WILL KEEP THE EASTERN CWA FAIRLY CLOUDY TODAY AND TRY TO MARK SOME CLEARING ACROSS THE WEST BY MIDDAY. MAIN CONCERN WILL BE WITH FOG POTENTIAL TONIGHT ACROSS THE NORTH...WITH WINDS STILL FAIRLY LIGHT AND SOME POTENTIAL FOR SNOW MELT TODAY. SHOULD SKIES STAY CLOUDY...THIS WOULD BE LESS OF A CONCERN. TEMPERATURE-WISE...WILL CONTINUE THE TREND OF KEEPING HIGHS A FEW DEGREES COOLER ACROSS THE NORTH WHERE THE SNOW DEPTH RANGES FROM 5 TO 9 INCHES. HOWEVER...EVEN THESE AREAS MAY CRACK 40 BY FRIDAY... WITH HIGHS 45-50 FURTHER SOUTH. LONG TERM...SATURDAY THROUGH WEDNESDAY... UPPER LOW IN THE PACIFIC NORTHWEST SHOULD BETTER ORGANIZE AS IT DROPS SOUTHWARD ALONG THE CALIFORNIA COAST TONIGHT AND FRIDAY. LATEST MODEL GUIDANCE CONTINUES TO EJECT THIS FEATURE NORTHEAST THIS WEEKEND...AS A DEEPENING SHORTWAVE TRACKS EAST ACROSS THE CANADIAN PRAIRIES. SOME PHASING OF THE TWO FEATURES IS INDICATED LATER THIS WEEKEND OVER THE CENTRAL U.S. AND THIS WILL SIGNIFICANTLY INCREASE PRECIP CHANCES AS THE WEEKEND PROGRESSES. GOOD MOISTURE SURGE SHOULD TAKE PLACE AHEAD OF THIS PHASING... WITH GFS PRECIPITABLE WATER VALUES OF 1.25 INCHES SATURDAY NIGHT NEAR THE 99TH PERCENTILE FOR EARLY MARCH. WOULD NOT BE SURPRISED TO SEE OVER AN INCH OF RAIN IN SOME AREAS SATURDAY NIGHT THROUGH SUNDAY NIGHT. HAVE INTRODUCED CATEGORICAL RAIN CHANCES SATURDAY NIGHT NORTHWEST OF THE ILLINOIS RIVER...AND ALSO ADDED AREAS OF FOG ACROSS THE NORTHERN CWA DUE TO THE HEAVIER RAIN AND RAPID SNOW MELT. SUNDAY WILL START OUT RATHER WET AS WELL. HOWEVER...THE MODELS BEGIN TO DIVERGE IN TERMS OF WHETHER A DRY SLOT MAY SPREAD IN DURING THE DAY. WITH THE DIVERSITY...WILL NOT TRY TO GET TOO CUTE WITH SPLITTING OUT MORNING AND AFTERNOON PERIODS. TEMPERATURES BOTH DAYS SHOULD REACH WELL INTO THE 50S. SUNDAY NIGHT AND MONDAY...THE GFS AND ECMWF MODELS BOTH SHOW THE NORTHERN WAVE EXITING THE AREA...WHILE ANOTHER LOW DEVELOPS OVER THE SOUTHERN PLAINS. THE GFS IS MORE AGGRESSIVE WITH CLOSING THIS LOW OFF AND LIFTING IT NORTHEAST...WHILE THE ECMWF WEAKENS BACK INTO AN OPEN WAVE. LEANING MORE TOWARD THE ECMWF SOLUTION FOR NOW...AND HAVE LIMITED LIKELY POPS SUNDAY NIGHT TO THE SOUTHEAST THIRD OF THE CWA. HAVE KEPT SOME PRECIP CHANCES IN ON MONDAY FOR NOW...BUT CONFIDENCE IS LOW AT THE MOMENT. HAVE LARGELY KEPT THE PRECIP AS RAIN EXCEPT FOR A MIX IN THE NORTHWEST. MODEL AGREEMENT DOES NOT IMPROVE AS THE WEEK PROGRESSES...WITH THE LONGER RANGE SOLUTIONS VARYING WITH THE STRENGTH OF ANOTHER WAVE DROPPING INTO THE GREAT LAKES ON TUESDAY. THE ECMWF SOLUTION WOULD BE MUCH COOLER FOR US WITH SIGNIFICANT RIDGING WEST OF THE ROCKIES. FOR NOW HAVE KEPT TEMPERATURES ABOUT 5 DEGREES BELOW NORMAL FOR THE END OF THE FORECAST PERIOD. GEELHART && .AVIATION... ISSUED 1150 PM CST WED MAR 6 2013 BROKEN TO OVERCAST MVFR CEILINGS OF 1.5-2.5K FT TO PREVAIL DURING OVERNIGHT ACROSS THE CENTRAL IL TERMINAL AIRPORTS...AS STRONG INVERSION FROM 900-750 MB TRAPS LOW LEVEL MOISTURE/CLOUDS (1-2K FT THICK) WITH WEAK NNW FLOW. USED RAP MODEL 925-850 MB RH FIELD FOR SCATTERING OUT THIS LOW CLOUD DECK FIRST AT SPI AND PIA BETWEEN 11-13Z AND LAST AT CMI AFTER 16Z THU. COULD BE VSBYS OF 4-6 MILES AS CLOUDS SCATTER OUT THU MORNING. ALSO HAVE REPORTS OF FLURRIES PAST FEW HOURS AT CMI AND COULD BE A CHANCE OF FLURRIES OVERNIGHT MAINLY ALONG I-74 TAF SITES. NW WINDS OF 5-10 KTS TO DIMINISH LIGHT DURING OVERNIGHT AND VEER NORTHERLY. LIGHT AND VARIABLE WINDS EXPECTED THU AS 1030 MB HIGH PRESSURE RIDGE FROM EASTERN MN/IA AND INTO MO DRIFTS EAST ACROSS IL BY 18Z/NOON THU. 07 && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1152 PM CST WED MAR 6 2013 .DISCUSSION... ISSUED 900 PM CST WED MAR 6 2013 UPDATED THE FORECAST TO KEEP LOW CLOUDS IN THE FORECAST LONGER TONIGHT AND ALSO NUDGE LOW TEMPERATURES UP A BIT DUE TO LINGERING LOW CLOUDS. MOSTLY CLOUDY TO OVERCAST SKIES TONIGHT EXCEPT LESS CLOUD COVER OVER 4 SW COUNTIES OF SCHUYLER...SCOTT...CASS AND MORGAIN FROM JACKSONVILLE SW. LOWS IN THE LOW TO MID 20S EXPECT SOME UPPER TEENS FROM GALESBURG TO JACKSONVILLE WEST. NW WINDS 5-10 MPH TURNING LIGHT NNW LATER TONIGHT. OVERCAST LOW CLOUDS FROM 1.5-3K FT BLANKET MUCH OF CENTRAL AND NE IL INTO SE IA/WI AT MID EVENING WITH CLEARING SW OF JACKSONVILLE. CLOUD LAYER IS ABOUT 1-2 K FT THICK PER KILX/KDVN SOUNDINGS AND PILOT REPORTS THIS EVENING. 00Z KILX SOUNDING SHOWS STRONG INVERSION FROM JUST ABOVE 900 MB TO 750 MB SO THIS IS TRAPPING LOW LEVEL MOISTURE/CLOUDS OVER CENTRAL/SE IL TONIGHT WITH LIGHTER FLOW. RAP MODEL 925-850 MB RH CAPTURING THIS CLOUD FIELD WELL WHICH KEEPS ABUNDANT LOW CLOUDS OVER CENTRAL AND SE THROUGH THE NIGHT WITH SOME DECREASING OF LOW CLOUDS FROM PEORIA TO TAYLORVILLE LATER TONIGHT AND INTO EASTERN IL DURING THU MORNING AS 1030 MB HIGH PRESSURE RIDGE OVER MN INTO CENTRAL IA/MO DRIFTS EAST ACROSS THE MS VALLEY INTO IL THU. A LIGHT FOG COULD DEVELOP OVER WEST CENTRAL AND NW IL LATER TONIGHT WHERE LESS LOW CLOUDS AND LIGHTER NNW WINDS PREVAIL. 07 && .AVIATION... ISSUED 1150 PM CST WED MAR 6 2013 BROKEN TO OVERCAST MVFR CEILINGS OF 1.5-2.5K FT TO PREVAIL DURING OVERNIGHT ACROSS THE CENTRAL IL TERMINAL AIRPORTS...AS STRONG INVERSION FROM 900-750 MB TRAPS LOW LEVEL MOISTURE/CLOUDS (1-2K FT THICK) WITH WEAK NNW FLOW. USED RAP MODEL 925-850 MB RH FIELD FOR SCATTERING OUT THIS LOW CLOUD DECK FIRST AT SPI AND PIA BETWEEN 11-13Z AND LAST AT CMI AFTER 16Z THU. COULD BE VSBYS OF 4-6 MILES AS CLOUDS SCATTER OUT THU MORNING. ALSO HAVE REPORTS OF FLURRIES PAST FEW HOURS AT CMI AND COULD BE A CHANCE OF FLURRIES OVERNIGHT MAINLY ALONG I-74 TAF SITES. NW WINDS OF 5-10 KTS TO DIMINISH LIGHT DURING OVERNIGHT AND VEER NORTHERLY. LIGHT AND VARIABLE WINDS EXPECTED THU AS 1030 MB HIGH PRESSURE RIDGE FROM EASTERN MN/IA AND INTO MO DRIFTS EAST ACROSS IL BY 18Z/NOON THU. 07 && .PREV DISCUSSION... ISSUED 231 PM CST WED MAR 6 2013 MODELS IN REASONABLE AGREEMENT OVER THE 7-DAY PERIOD...PARTICULARLY GIVEN THE PRIMARY ENERGY TO IMPACT ILLINOIS THIS WEEKEND IS RELATIVELY POORLY SAMPLED OFF THE PACIFIC COAST. SHORT TERM...TONIGHT THROUGH SATURDAY STORM SYSTEM THAT BROUGHT SNOW TO FORECAST AREA YESTERDAY IS NOW ALONG THE MID-ATLANTIC COAST AND CONTINUES TO DIMINISH ITS IMPACT ON ILLINOIS AS HIGH PRESSURE OVER MID-MISSOURI VALLEY PUSHES EASTWARD. PLENTIFUL CLOUDINESS PERSISTS TO THE EAST OF THE RIDGE AXIS AND WILL ONLY GRADUALLY DIMINISH AS THE RIDGE PUSHES EAST TONIGHT. WILL HAVE TO MONITOR CLOSELY AS DEVELOPING BREAKS MAY LEAD TO LOWER TEMPS THAN FORECAST IN SNOW COVERED AREAS AS WELL AS A POTENTIAL FOR FOG...PARTICULARLY WESTERN COUNTIES. THERE HAS BEEN SOME SNOW MELT/COMPACTION TODAY IN OCCASIONAL SUNSHINE DESPITE THE COLD TEMPERATURES. HAVE TEMPERED TOMORROWS HIGH FORECAST A TAD GIVEN THE IMPACT OF THE REMAINING SNOW...BUT WITH MARCH SUN AND RAPIDLY RISING 850 TEMPS...FEEL SNOW MAY ONLY HAVE A MINOR IMPACT ON FRIDAYS TEMPS AND SHOULD BE GONE BY SATURDAY. WITH LIGHT WINDS IN PLACE WITH DEEP RIDGING WILL HAVE TO MONITOR CONDITIONS FOR POTENTIAL OF FOG BOTH THURSDAY AND FRIDAY NIGHTS. BY SATURDAY AFTERNOON SOUTHEAST WINDS AND 850 TEMPERATURES INCREASING TO AROUND 10C SHOULD SUPPORT HIGHS REACHING INTO THE 50S. LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY STRONG SYSTEM CURRENTLY OFF THE NW PACIFIC COAST IS PROGGED TO PLUNGE INTO THE SW U.S. AND THEN APPROACH ILLINOIS BY SATURDAY NIGHT. WITH THIS SHIFT TO MORE OF PACIFIC STORM TRACK...PRECIP WITH THIS NEXT SYSTEM SHOULD BE MOSTLY RAIN. ENERGY IS EXPECTED TO BE EJECTED TOWARD US IN A PIECEMEAL FASHION PROVIDING US WITH SEVERAL WAVES OF PRECIP INTO MONDAY. RAINFALL AMOUNTS MAY BE SIGNIFICANT...PARTICULARLY IN OUR NORTHERN COUNTIES WHERE SNOWMELT RUNOFF WILL CONTRIBUTE. PRECIP WATER FORECASTS FROM THE GFS HAVE VALUES AS HIGH AS 1.15 INCHES LATE SATURDAY NIGHT WHICH IS 2+ SD ABOVE NORMAL FOR MARCH. TOTAL 48-HOUR AMOUNTS MAY LOCALLY APROACH 2 INCHES. SOME COLDER AIR FILTERS IN BEHIND THE LOW ON MONDAY...BUT BOUNDARY LAYER TEMPS AT THIS POINT SUGGEST THAT THE PRECIP MAY ONLY BRIEFLY MIX WITH OR CHANGE TO SNOW BEFORE ENDING. IN WAKE OF SYSTEM...TEMPS SHOULD BE 5-10 DEGREES BELOW NORMAL THROUGH WEDNESDAY. COLDER TEMPS SHOULD REMAIN NORTH OF THE AREA WITH HIGH ZONAL COMPONENT UPPER LEVEL FLOW. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1122 AM CST THU MAR 7 2013 .UPDATE... THE STRONGER MARCH SUN HAS STARTED TO ERODE THE LOW CLOUDS OVER THE SOUTHWEST PART OF THE CWFA WITH SOME ADDITIONAL INROADS ACROSS THE FAR SOUTH. IF CURRENT SATELLITE TRENDS HOLD...THE NORTHWEST MOVEMENT OF THE CLOUDS APPEARS TO HAVE REACHED ITS MAXIMUM AND THERE SHOULD BE A SLOW EROSION AROUND THE EDGES DURING THE AFTERNOON. ..08.. && .AVIATION... CURRENT 1-2KFT AGL CLOUDS ARE NOT BEING HANDLED WELL BY ANY MODEL. WEAK SOUTHEAST FLOW IN THE LOW LEVELS HAS ADVECTED THE CLOUDS NORTHWEST BUT THE STRONGER MARCH SUN MAY HAVE STOPPED THE NORTHWEST MOVEMENT. MVFR CONDITIONS WILL BE SEEN AT KDBQ/KMLI/KBRL WITH AN EVENTUAL IMPROVEMENT TO VFR EITHER PRIOR TO 00Z/08 OR BY 12Z/08. KCID SHOULD REMAIN VFR BUT MAY HAVE BRIEF INCURSIONS OF MVFR THROUGH 21Z/07. ..08.. && .PREV DISCUSSION... /ISSUED 1012 AM CST THU MAR 7 2013/ UPDATE... BASED ON DATA THROUGH MID MORNING WILL BE DOING A SIGNIFICANT REVISION TO THE FCST FOR CLOUDS. 12Z UA DATA HAS A VERY THIN LAYER OF MOISTURE IN THE SOUNDINGS TRAPPED BELOW THE INVERSION. THIS LAYER IS ON THE ORDER OF 200-300 FT THICK AND IS ROUGHLY 0.75 TO 0.90 KM ABOVE THE GROUND. THE RAP MODEL AT LEAST HAS CLOUDS BUT THEY ARE TOO LOW IN THE FCST SOUNDINGS. THE RAP TRENDS AT THE 0.5 AND 1 KM LEVELS SHOW VERY WEAK SOUTHEAST TO SOUTH SOUTHEAST FLOW WITH A SLOW UPGLIDE ON THE CONDENSATION PRESSURE LEVELS. ADD TO THIS WAA OCCURRING ALOFT AND THE INVERSION SHOULD ONLY STRENGTHEN DURING THE DAY. THE STRONGER MARCH SUN SHOULD ALLOW SOME BREAKS TO DEVELOP IN THE CLOUDS BUT THE OVERALL SIGNAL SUGGESTS THAT CLOUDS WILL REMAIN ACROSS THE AREA. RECENT SATELLITE TRENDS ARE SHOWING A SLOW DRIFT TO THE NORTHWEST WITH THE LOW CLOUDS AS HIGHER CLOUDS MOVE IN FROM THE WEST. THIS TREND WITH THE LOW CLOUDS WILL LIKELY CONTINUE FOR SEVERAL MORE HOURS AND MAY EVENTUALLY STOP. ANY CLEARING THAT OCCURS TODAY WILL BE FROM THE SOUTH AND WILL BE VERY SLOW. THE CLOUD COVER WILL THEN HAVE AN IMPACT ON TEMPERATURES WITH A POTENTIAL SLIGHT LOWERING OF HIGHS FOR AREAS UNDER THE CLOUDS. IF THE RAP TRENDS ARE CORRECT...THE CLOUDS MAY PERSIST INTO TONIGHT. ..08.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1012 AM CST THU MAR 7 2013 .UPDATE... BASED ON DATA THROUGH MID MORNING WILL BE DOING A SIGNIFICANT REVISION TO THE FCST FOR CLOUDS. 12Z UA DATA HAS A VERY THIN LAYER OF MOISTURE IN THE SOUNDINGS TRAPPED BELOW THE INVERSION. THIS LAYER IS ON THE ORDER OF 200-300 FT THICK AND IS ROUGHLY 0.75 TO 0.90 KM ABOVE THE GROUND. THE RAP MODEL AT LEAST HAS CLOUDS BUT THEY ARE TOO LOW IN THE FCST SOUNDINGS. THE RAP TRENDS AT THE 0.5 AND 1 KM LEVELS SHOW VERY WEAK SOUTHEAST TO SOUTH SOUTHEAST FLOW WITH A SLOW UPGLIDE ON THE CONDENSATION PRESSURE LEVELS. ADD TO THIS WAA OCCURRING ALOFT AND THE INVERSION SHOULD ONLY STRENGTHEN DURING THE DAY. THE STRONGER MARCH SUN SHOULD ALLOW SOME BREAKS TO DEVELOP IN THE CLOUDS BUT THE OVERALL SIGNAL SUGGESTS THAT CLOUDS WILL REMAIN ACROSS THE AREA. RECENT SATELLITE TRENDS ARE SHOWING A SLOW DRIFT TO THE NORTHWEST WITH THE LOW CLOUDS AS HIGHER CLOUDS MOVE IN FROM THE WEST. THIS TREND WITH THE LOW CLOUDS WILL LIKELY CONTINUE FOR SEVERAL MORE HOURS AND MAY EVENTUALLY STOP. ANY CLEARING THAT OCCURS TODAY WILL BE FROM THE SOUTH AND WILL BE VERY SLOW. THE CLOUD COVER WILL THEN HAVE AN IMPACT ON TEMPERATURES WITH A POTENTIAL SLIGHT LOWERING OF HIGHS FOR AREAS UNDER THE CLOUDS. IF THE RAP TRENDS ARE CORRECT...THE CLOUDS MAY PERSIST INTO TONIGHT. ..08.. && .PREV DISCUSSION... /ISSUED 547 AM CST THU MAR 7 2013/ SYNOPSIS... ISSUED AT 341 AM CST THU MAR 7 2013 ANOTHER RELATIVELY QUIET MORNING ACROSS THE AREA WITH THE STRONG SURFACE RIDGE OVER THE FORECAST AREA. STRATUS LINGERS OVER THE FORECAST AREA NEAR AND EAST OF THE SURFACE RIDGE. WHERE THE STRATUS HAS CLEARED OUT...PATCHY TO AREAS OF FOG HAVE DEVELOPED...MAINLY OVER THE NORTHERN PORTIONS OF EASTERN IOWA WHERE THE STRATUS CLEARED EARLY IN THE EVENING. CLOSER TO THE WESTERN EDGE OF THE STRATUS THE FOG IS LESS. THE FOG HAS NOT BEEN CONSISTENT IN AREAL COVERAGE...WITH SITES VARYING WIDELY IN VISIBILITY OVER THE LAST FEW HOURS. ALOFT...WE HAVE RIDGING AT NEARLY ALL LEVELS OVER THE MIDWEST WITH VERY DRY 850MB AIR OVER THE AREA. THE STORM THAT BROUGHT SNOW TO THE AREA TUESDAY IS NOW JUST OFF THE EAST COAST. ..LE.. SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 341 AM CST THU MAR 7 2013 DECEPTIVELY QUIET FORECAST WITH THE MAIN CONCERNS OVER THE FOG EARLY THIS MORNING...THE EXPECTED GRADUAL DIMINISHING OF THE STRATUS...AND TEMPERATURES TODAY AND TONIGHT. THIS MORNINGS FOG IS A CLASSIC RADIATIONAL FOG EVENT WITH THE SURFACE RIDGE OVERHEAD...LIGHT WINDS AND SMALL DEWPOINT DEPRESSIONS. HOWEVER...FOG IS VERY PATCHY IN NATURE AND VISIBILITIES HAVE BEEN RANGING FROM A FEW QUARTER MILE REPORTS TO P6SM. HOWEVER...WITH DAWN APPROACHING AND TEMPERATURES GETTING CONSISTENTLY CLOSER TO MINS...WE MAY HAVE A MORE CONSISTENT COVERAGE OF THE FOG HERE IN THE NEXT FEW HOURS. FOR NOW...HAVE HELD OFF ON DOING A DENSE FOG ADVISORY BUT WILL KEEP A CLOSE EYE ON CONDITIONS AND REEVALUATE AT NEED. THE STRATUS SHOULD FINALLY MOVE OFF TO THE EAST TODAY WITH WARM AIR ADVECTION MOVING IN ALOFT...WARMER TEMPERATURES AND SOME MIXING OF THE COLUMN TO HELP DISSIPATE THE STRATUS FROM WEST TO EAST. ALSO...AS THE LOW LEVEL RIDGE SHIFTS EAST AND THIS SHOULD HELP TO BODILY SHIFT THE STRATUS EAST...DESPITE THE WINDS BENEATH THE INVERSION GOING FROM NEARLY CALM TO LIGHT SOUTHEAST...WHICH WOULD BRING THE STRATUS BACK INTO THE AREA. THUS...HAVE GRADUALLY CLEARED CLOUDS DURING THE MORNING HOURS AND WE SHOULD HAVE A SUNNY OR MOSTLY SUNNY AFTERNOON. MIXING OF THE LOWEST LAYERS AND WARM AIR ADVECTION SETTING IN ALOFT IN COMBINATION WITH SOME MORE SUNSHINE SHOULD HELP BOOST TEMPERATURES TODAY. HAVE PUT HIGH TEMPERATURES IN THE 30S NEARLY EVERYWHERE...BUT WOULD NOT BE SURPRISED TO SEE TEMPS IN THE SOUTHWEST APPROACH 40 THIS AFTERNOON AS LONG AS THE STRATUS CLEARS FAIRLY EARLY THIS MORNING. TONIGHT...WARM AIR ADVECTION GOING ON ALOFT...LIGHT SOUTHEAST WINDS AND INCREASING HIGHER CLOUDS SHOULD KEEP TEMPERATURES WARMER THAN THE CLOUD FREE AREAS THIS MORNING...AND HAVE MIN TEMPS IN THE UPPER TEENS TO MID 20S. .LE.. LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 341 AM CST THU MAR 7 2013 CHALLENGING WEEKEND SYSTEM REMAINS THE FOCUS OF THE EXTENDED FORECAST. THE LAST COUPLE RUNS OF THE GFS AND ECMWF HAVE MIGRATED TOWARD A WEAKER...LESS PHASED UPPER WAVE LIFTING OUT OF THE SW. BOTH DEPICT THE INITIAL UPPER LOW OVER THE FOUR CORNERS REGION SATURDAY MORNING LIFTING NORTHEAST...PHASING WITH A NORTHERN STREAM TROUGH AND SWEEPING NORTHEAST INTO SE CANADA. A SECONDARY PIECE OF ENERGY BREAKS OFF AND STAYS TO THE SOUTH...MOVING THROUGH THE MID MS VALLEY AND THEN OHIO RIVER VALLEY MONDAY. THIS WOULD PRODUCE A WEAKER...LESS ORGANIZED SURFACE LOW THAT LIFTS NORTHEAST ALONG THE PASSING COLD FRONT LATE SATURDAY NIGHT AND EARLY SUNDAY. THE NET RESULT IS A FASTER SYSTEM...NOW MORE LIKELY TO EXIT THE AREA BY SUNDAY EVENING WITH POSSIBLY LOWER QPF TOTALS FROM RAIN AND LESS POTENTIAL FOR MEASURABLE SNOW BEHIND THE COLD FRONT. FRIDAY NIGHT...ELEVATED WARM ADVECTION AND MOISTURE RETURN ON A 40 KT 850 MB JET MAY SPREAD SHOWERS INTO ESPECIALLY THE WESTERN HALF OF THE FORECAST AREA AFTER MIDNIGHT. THERE REMAINS A POTENTIAL THAT SURFACE TEMPERATURES MAY INITIALLY BE NEAR OR BELOW FREEZING ACROSS THE NORTH AND NORTHEAST AND WILL KEEP A MENTION OF FREEZING RAIN. SATURDAY SHOULD SEE PRECIPITATION DUE TO THE WARM ADVECTION AND INCREASINGLY DIFFLUENT FLOW ALOFT...BUT AT THIS TIME IT LOOKS TO BE MORE OF A SHOWERY NATURE. THE BEST POTENTIAL FOR WIDESPREAD RAIN SHOULD BE IN THE WEST CLOSER TO THE APPROACHING FRONT WHERE POPS ARE GREATEST. OTHERWISE...TEMPERATURES AND DEWPOINTS SHOULD RISE WELL INTO THE 40S WITH SOUTHEAST WINDS LIKELY STRONG ENOUGH TO KEEP ADVECTION FOG AT BAY. WIDESPREAD RAIN WILL BE FOCUSED ON SATURDAY NIGHT WITH THE PASSAGE OF THE UPPER LEVEL WAVE AND THEN SURFACE COLD FRONT TOWARD MORNING. WIDESPREAD QPF AMOUNTS OF .5 TO 1 INCH STILL LOOK REASONABLE...WITH POSSIBLE LOCALLY HIGHER AMOUNTS IF ANY CONVECTION TAKES PLACE. LINGERING SNOW COVER MAY EFFECTIVELY CAPTURE MUCH OF THIS RAIN...WHICH WOULD DELAY OR PROLONG THE RUNOFF...WHILE AT THE SAME TIME COULD ALSO LEAD TO MINOR URBAN FLOODING DUE TO CLOGGED DRAINAGE. ANOTHER CONCERN WILL BE THE POTENTIAL FOR WIDESPREAD FOG DUE TO LIGHT WINDS AND LOW LEVEL CONVERGENCE ALONG THE FRONT AND PASSING WEAK SURFACE WAVE. HAVE ADDED FOG WORDING TO THE FORECAST...BUT WILL HOLD OFF ON MENTIONING HYDRO CONCERNS UNTIL CONFIDENCE OF HEAVIER QPF INCREASES. SUNDAY...THE COLD FRONT IS NOW SHOWN EAST OF THE AREA BY MIDDAY WITH LITTLE UPPER LEVEL FORCING POST FRONTAL AS THE UPPER TROUGH SHIFTS EAST BY EVENING. COLD ADVECTION MAY CHANGE RAIN TO SNOW...BUT AT THIS TIME IT LOOKS LIKE MINIMAL ACCUMULATIONS WITH ANY PRECIPITATION LIKELY ENDING BY EARLY EVENING. ADVERTISED FORECAST HIGHS...IN THE 40S TO AROUND 50...WOULD OCCUR EARLY IN THE DAY...AND IF THE CURRENT TIMING HOLDS...THESE NUMBERS MAY BE A CATEGORY OR TWO TO MILD. MONDAY THROUGH WED...SURFACE HIGH PRESSURE AND NW FLOW ALOFT SHOULD PROVIDE CONTINUED BELOW NORMAL TEMPERATURES. OUTSIDE OF A CLIPPER SYSTEM CURRENTLY SHOWN PASSING WELL TO THE NORTH AROUND TUESDAY...THERE WILL BE LITTLE POTENTIAL FOR PRECIPITATION. SHEETS AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 546 AM CST THU MAR 7 2013 STRATUS AND FOG TO DOMINATE THE AVIATION FORECAST THIS MORNING. KMLI AND KBRL STILL AFFECTED BY MVFR STRATUS WITH CIGS AROUND 1800FT. THIS STRATUS IS HOLDING STEADY BUT SHOULD GRADUALLY MOVE EAST IN THE MORNING AND SHOULD CLEAR AND RETURN TO VFR BETWEEN 15Z- 18Z. KCID AND KDBQ ARE NOT UNDER THE STRATUS BUT HAVE DEVELOPED FOG WITH HIGHLY VARIABLE VISIBILITIES AND VERTICAL VISIBILITIES. CONDITIONS ARE LIFR AT TIMES...BUT THIS SHOULD DISSIPATE BY 16Z. VERY LIGHT WINDS TO TURN SOUTHEAST BUT REMAIN LESS THAN 8KTS THROUGH THE PERIOD. FOG IS POSSIBLE AGAIN TONIGHT...AND HAVE PUT SOME MVFR FOG INTO TERMINALS AFTER 08Z...THOUGH CONFIDENCE IN TIMING OR LOCATION IS NOT VERY HIGH. .LE.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1123 PM CST WED MAR 6 2013 .AVIATION... A DIFFICULT CLEARING TREND WILL DOMINATE THE AVIATION FORECAST EARLY TODAY OVER SOUTHEAST IOWA AND NEAR MLI...WITH CLEARING POSSIBLY DELAYED UNTIL 12 TO 15Z. THE CIGS REMAIN MVFR AROUND 1800 FT. WHILE CID AND DBQ ARE CLEAR...THEY WILL SEE A RISK OF IFR TO LIFR FOG AND VV002 STRATUS DEVELOPMENT THROUGH SUNRISE...MLI AND BRL SHOULD REMAIN CLOUDY ENOUGH THAT FOG DOES NOT BECOME AN ISSUE. VERY LIGHT WINDS WILL LAST THROUGH THURSDAY EVENING. && .PREV DISCUSSION... /ISSUED 541 PM CST WED MAR 6 2013/ UPDATE... SHORT TERM MODELS INCLUDING THE HRRR AND RAP13 CONTINUE TO REPRESENT THE STRATUS FIELD BEST...AND BOTH SUGGEST IT WILL HANG ON ALL NIGHT. AS SEEN ON SATELLITE TRENDS SINCE 430 PM...THE EDGE OF THE STRATUS IS NO LONGER MOVING/DISSIPATING. IF IT IS...IT IS NOW EXCRUCIATINGLY SLOW. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS WICHITA KS
905 PM CST FRI MAR 8 2013 .UPDATE... THE SCATTERED SHOWER CHANCES HAVE BEEN SLOW TO GET GOING ACROSS MOST OF THE FORECAST AREA AT THIS TIME. WITH MAINLY SOME WIDELY SCATTERED SPRITZES/SPRINKLES OR DRIZZLE. LOW LEVEL ISENTROPIC LIFT CONTINUES TO LEAD TO LOTS OF LOW-MID CLOUDS WITH THIS LOW LEVEL SATURATION LEADING TO GRADUALLY LOWER CEILINGS. THINK THE WIDESPREAD SHOWER CHANCES WILL WAIT UNTIL THE INITIAL IMPULSE /THAT IS LEADING TO THE LINE OF CONVECTION IN THE TX PANHANDLE/ BEGINS TO LIFT NORTHEAST INTO SRN KS AFTER MIDNIGHT.. THINK AS THIS IMPULSE LIFTS NORTH...SHOWERS WILL BECOME MORE WIDESPREAD FOR AREAS WEST OF INTERSTATE 135...WHERE BETTER MOISTURE TRANSPORT IS ALREADY IN PLACE. SHORT TERM RUC ALSO SHOWS SOME ELEVATED MUCAPE AROUND 400-600 J/KG MOVING INTO THIS AREA AS WELL...SO THINK SOME RUMBLES OF EMBEDDED THUNDER MAY ALSO MOVE IN AS WELL. CURRENT GRIDS/ZONES LOOK RIGHT ON TRACK...WITH POPS A LITTLE HIGH EARLY ON...BUT THEY LOOK FINE FOR AFTER MIDNIGHT. KETCHAM && .PREV DISCUSSION... /ISSUED 558 PM CST FRI MAR 8 2013/ AVIATION...00Z TAFS KRSL/KSLN/KHUT/KICT/KCNU MVFR CEILINGS WILL GRADUALLY MOVE INTO MOST OF THE TAF SITES THIS EVENING. EXPECT DETERIORATING AVIATION CONDITIONS OVERNIGHT TO IFR CONDITIONS BETWEEN 06-12Z/SAT AT MOST LOCATIONS AS WIDESPREAD SHOWERS DEVELOP. COULD ALSO SEE SOME EMBEDDED THUNDER AS WELL FOR MOST TAF LOCATIONS BETWEEN 12-18Z/SAT. THE DRY LINE ASSOCIATED WITH THIS STORM SYSTEM WILL PUSH INTO THE KRSL/KHUT AND KICT TAF SITES LATE IN THE TAF PERIOD...WHICH WILL SCOUR OUT THE IFR CEILINGS. THIS DRYING OUT OF THE LOW LAYERS...AND SOME POSSIBLE HEATING DUE SOME PEAKS OF SUNSHINE MAY ALSO LEAD TO A RENEWED CHANCE OF THUNDERSTORMS...SO WILL INCLUDE A VCTS FOR THIS CHANCE FOR THE KHUT/KRSL/KSLN AND KICT TAF SITES. KETCHAM PREV DISCUSSION... /ISSUED 328 PM CST FRI MAR 8 2013/ DISCUSSION... FORECAST HIGHLIGHTS FOCUS AROUND PRECIPITATION CHANCES TONIGHT-SUNDAY...INCLUDING THE POTENTIAL FOR A FEW STRONG SEVERE STORMS SATURDAY AFTERNOON-EVENING...AND SNOW SATURDAY NIGHT-SUNDAY MORNING. IMPRESSIVE LOOKING UPPER LOW WITH QUITE A BIT OF LIGHTNING IS CURRENTLY SPINNING OVER THE DESERT SOUTHWEST. AS THIS STORM SYSTEM APPROACHES THE REGION TONIGHT...ANTICIPATING WIDESPREAD SHOWERS WITH EMBEDDED THUNDERSTORMS TO BE ON THE INCREASE...ESPECIALLY AFTER MIDNIGHT GENERALLY OVER CENTRAL AND SOUTH-CENTRAL KS. GIVEN WEAK INSTABILITY...CANNOT RULE OUT SMALL HAIL WITH THE STRONGEST STORMS. THIS WIDESPREAD SHIELD OF SHOWERS/THUNDERSTORMS WILL GRADUALLY SHIFT EAST ACROSS THE AREA DURING THE DAY SATURDAY...IN ZONE OF STRONG LOW TO MID-LEVEL WARM/MOIST ADVECTION AHEAD OF APPROACHING UPPER WAVE. BY TOMORROW MID-AFTERNOON...BRUNT OF MAIN PRECIPITATION SHIELD SHOULD BE OVER THE EASTERN 1/3 OF KS...WITH SURFACE DRYLINE HANGING BACK WESTWARD OVER CENTRAL/SOUTH-CENTRAL KS...AND COOLING/DRYING ALOFT OVERSPREADING THE WARM SECTOR AHEAD OF APPROACHING SHORTWAVE. IF BREAKS IN OVERCAST CAN DEVELOP ALLOWING SOME HEATING IN WAKE OF MAIN PRECIPITATION SHIELD...THINKING THERE COULD BE A WINDOW OF OPPORTUNITY FROM MID-AFTERNOON THROUGH EARLY EVENING FOR SCATTERED SHALLOW/LOW-TOPPED SURFACE BASED CONVECTION GENERALLY ALONG/WEST OF I-135 CORRIDOR. IF ENOUGH INSTABILITY CAN MATERIALIZE FOR STORMS...LOW-TOPPED SUPERCELLS WILL BE POSSIBLE GIVEN STRONGLY SHEARED ENVIRONMENT...WITH THE POTENTIAL FOR SOME LARGE HAIL. ADDITIONALLY...NAM BUFR SOUNDINGS INDICATE DECENT LOW-LEVEL CAPE OWING TO MID-UPPER 50F DEWPOINTS AND STEEPENING LAPSE RATES...WHICH WOULD SUPPORT THE POTENTIAL FOR AN ISOLATED TORNADO OR TWO. WILL NOT COMPLETELY BITE ONTO THE OMINOUS NAM SOLUTION JUST YET GIVEN AFTERNOON HEATING/INSTABILITY QUESTIONS...BUT DEFINITELY SOMETHING FOR THE NIGHT SHIFT TO EVALUATE FURTHER. BY SATURDAY NIGHT-EARLY SUNDAY...AS UPPER LOW SHIFTS EAST AND MUCH COLDER AIR FILTERS SOUTH...THINKING CENTRAL KS COULD SEE A PERIOD OF LIGHT SNOW. CURRENT INDICATIONS SUGGEST HEAVIEST SNOW WILL REMAIN OFF TO THE NORTH/NORTHWEST...BUT PORTIONS OF CENTRAL KS COULD RECEIVE UP TO 1 INCH OR SO AFTER MIDNIGHT SATURDAY NIGHT THROUGH SUNDAY MORNING. SUNDAY WILL LIKELY BE THE COLDEST DAY OF THE NEXT 7-10 DAYS...WITH HIGHS IN THE 30S-40S AND A STOUT NORTH WIND. GIVEN CURRENT MODEL CONSENSUS...CONFIDENCE IS MODERATE TO HIGH THAT DRY AND WARMING CONDITIONS WILL PREVAIL MONDAY THROUGH NEXT WEEKEND...AS MID/UPPER FLOW FLATTENS OUT SOME AND ATMOSPHERIC HEIGHTS/THICKNESS INCREASES. HIGHS IN THE 50S-60S APPEAR LIKELY. ADK && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 52 62 35 40 / 70 80 40 30 HUTCHINSON 52 63 33 39 / 70 70 40 40 NEWTON 51 61 33 38 / 70 80 50 40 ELDORADO 51 60 35 41 / 70 80 50 30 WINFIELD-KWLD 52 61 37 42 / 70 80 50 20 RUSSELL 52 65 29 38 / 50 50 60 60 GREAT BEND 53 67 30 39 / 50 50 60 60 SALINA 52 63 32 38 / 60 70 50 50 MCPHERSON 52 63 32 38 / 70 70 50 50 COFFEYVILLE 53 61 44 46 / 50 90 70 30 CHANUTE 51 59 42 44 / 50 90 70 40 IOLA 50 59 41 44 / 50 90 70 40 PARSONS-KPPF 52 60 42 45 / 50 90 70 30 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
252 AM MST THU MAR 7 2013 .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 248 AM MST THU MAR 7 2013 A RIDGE WILL BE OVER THE PLAINS TODAY AND TONIGHT AND THEN SHIFT EAST FRIDAY. SOUTHWEST FLOW WILL BE OVER THE CENTRAL PLAINS FRIDAY NIGHT WITH AN UPPER LOW OVER NORTHERN ARIZONA. THE UPPER LOW WILL MOVE INTO SOUTHEAST COLORADO SATURDAY AND INTO SOUTHEAST NEBRASKA SATURDAY NIGHT. A SURFACE TROUGH WILL MOVE INTO EASTERN COLORADO TODAY AND TONIGHT. BY FRIDAY A LARGE AREA OF LOW PRESSURE WILL RESIDE OVER THE ROCKIES. A SURFACE LOW WILL BE CENTERED OVER EASTERN COLORADO/NORTHWEST FRIDAY NIGHT AND SATURDAY. THE LOW WILL SHIFT INTO NORTHEAST KANSAS SATURDAY NIGHT. DRY WEATHER WILL CONTINUE TODAY THROUGH FRIDAY. BOUNDARY LAYER RH ABOVE 90 PERCENT WILL BE FAVORABLE FOR FOG DEVELOPMENT TONIGHT AND EARLY FRIDAY MORNING ACROSS MOST OF THE FA. DYNAMICS START AFFECTING THE FA FRIDAY NIGHT BUT MOISTURE IS MARGINAL. THE GFS SHOWS A DRY SLOT OVERTAKING NEARLY ALL OF THE FA FRIDAY NIGHT EXCEPT FOR THE FAR NORTHWEST ZONES. FOR THIS REASON HAVE LOWERED POPS SOME. INSTABILITY DOES NOT LOOK AS WIDESPREAD SO HAVE KEPT THAT EAST OF THE COLORADO BORDER. FORECAST SOUNDINGS INDICATE SOME STRATUS AND POSSIBLY FOG MAINLY ACROSS THE NORTHEAST ZONES. THE DRY SLOT CONTINUES TO AFFECT THE FA SATURDAY MORNING SO HAVE REDUCED POPS SOME. THE DRY SLOT SHIFTS EAST OF THE FA SATURDAY AFTERNOON. GOOD MOISTURE MOVES INTO THE FA SO PLAN TO KEEP CURRENT HIGH CHANCE AND LIKELY POPS. ISOLATED THUNDER WILL REMAIN IN THE FORECAST BUT WILL SLOWLY SHIFT INTO THE EASTERN FA BY AFTERNOON. WRAPAROUND SNOW WILL SPREAD ACROSS THE ENTIRE FA SATURDAY NIGHT. WINDS WILL BE STRONG ENOUGH FOR BLOWING SNOW AS WELL. AT THIS TIME IT APPEARS THAT TOTAL SNOW AMOUNTS SHOULD VARY AROUND 3 INCHES FOR THE EVENT. SNOW SHOULD START DECREASING SOME LATE SATURDAY NIGHT. MAX TEMPERATURES SHOULD RISE INTO THE LOWER TO MID 60S TODAY OVER THE SOUTHWEST HALF OF THE FA WITH LOWER 50S IN THE EXTREME NORTHEAST FA. TEMPERATURES FRIDAY WILL BE COOLER WITH READINGS IN THE MID 50S. THE WEST WILL BE COLDER WITH UPPER 30S AND THE SOUTHEAST WILL REACH INTO THE LOWER 50S. MIN TEMPERATURES TONIGHT WILL BE IN THE UPPER 20S/LOWER 30S. LOWS FRIDAY NIGHT WILL BE EVEN WARMER WITH READINGS IN THE UPPER 30S WEST TO LOWER 40S EAST. LOW TEMPERATURES SATURDAY NIGHT WILL BE IN THE MID AND UPPER 20S. .LONG TERM...(SUNDAY THROUGH THURSDAY) ISSUED AT 1147 PM MST WED MAR 6 2013 SNOW WILL BE WINDING DOWN ON SUNDAY WITH ADDITIONAL ACCUMULATIONS OF LESS THAN AN INCH EXPECTED. HOWEVER...NORTHERLY WINDS WILL BE GUSTY AND RESULT IN AREAS OF BLOWING SNOW. SNOW WILL END BY SUNDAY NIGHT. THE REMAINDER OF THE PERIOD WILL BE DOMINATED BY UPPER RIDGING BUILDING ACROSS THE ROCKIES...RESULTING IN DRY CONDITIONS AND WARMING TEMPERATURES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1030 PM MST WED MAR 6 2013 POTENTIAL FOR OVERNIGHT FOG/STRATUS CONTINUES...WITH BEST CHANCES FOR REDUCTIONS IN FLIGHT CATEGORIES AT MCK. CONFIDENCE SOMEWHAT LOW ATTM THOUGH AS 00Z RAOBS AND RAP DATA LOWER CONFIDENCE IN HOW WIDESPREAD FOG POTENTIAL WILL BE. FOR THE TIME BEING...BROUGHT MCK DOWN TO MIDDLE OF THE ROAD/OPERATIONAL SIGNIFICANT MVFR FOR A PORTION OF THE OVERNIGHT HOURS. OTHERWISE...VFR CONDITIONS EXPECTED FOR THE REST OF THE PERIOD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...032 LONG TERM...024 AVIATION...JRM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1150 PM MST WED MAR 6 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 218 PM MST WED MAR 6 2013 AS OF 3 PM CST...2 PM MST...SKIES WERE MOSTLY CLEAR TO PARTLY CLOUDY AS SOME HIGH LEVEL CIRRUS MOVES FROM WEST TO EAST. TEMPERATURES RANGED FROM THE LOW 40S NEAR NORTON...KANSAS TO NEAR 60 DEGREES IN TRIBUNE...KANSAS. WINDS WERE GENERALLY FROM THE SOUTHEAST AT 15 TO 20 MPH WITH GUSTS UP TO 25 OR 30 MPH. A LEE TROUGH WAS DEVELOPING ACROSS EAST CENTRAL COLORADO. FOR TONIGHT...BREEZY SOUTHEAST WINDS WILL WEAKEN THIS EVENING. WINDS WILL BACK TO THE EAST OVER THE EASTERN FORECAST AREA...ALLOWING AIR WITH HIGHER MOISTURE CONTENT TO FILTER INTO THE AREA. LOW TEMPERATURES WILL DROP INTO THE LOW 20S. WITH LIGHT WINDS...HIGHER DEWPOINTS AND COLD TEMPERATURES...FOG IS EXPECTED TO DEVELOP ACROSS A LARGE AREA TONIGHT. ACROSS THE WESTERN FORECAST AREA...A LEE TROUGH TO THE WEST WILL MOVE TO THE EAST. WINDS WILL BE LIGHT AND VARIABLE JUST EAST OF THE TROUGH AND FROM THE WEST OR NORTHWEST AT 5-10 MPH AS THE TROUGH MOVES IN. THIS SHOULD KEEP THE FOG FROM ADVANCING INTO EASTERN COLORADO. FOG COULD BE DENSE...BUT WAS NOT CONFIDENT ENOUGH TO PLACE THIS INTO THE FORECAST AT THE CURRENT TIME. TEMPERATURES WILL BE HIGHLY VARIABLE ACROSS THE FORECAST AREA FOR TOMORROW. HIGHS ACROSS MOST OF EASTERN COLORADO AND PORTIONS OF NORTHWEST KANSAS WILL BE IN THE MID 60S TO NEAR 70 IN SOME SPOTS. FOG AND CLOUDS WILL LINGER INTO THE LATE MORNING HOURS FOR NORTHEAST PORTIONS OF THE FORECAST AREA. THIS WILL KEEP HIGH TEMPERATURES CONFINED TO THE LOWER 50S NEAR MCCOOK NEBRASKA AND HILL CITY KANSAS. LIGHT AND VARIABLE WINDS IN THE MORNING WILL BECOME SOUTHEAST AT 10 TO 15 MPH DURING THE AFTERNOON HOURS. AT THIS TIME...FIRE WEATHER IS NOT EXPECTED TO BECOME A CONCERN FOR TOMORROW. RELATIVE HUMIDITIES WILL DROP INTO THE 15 TO 25 PERCENT RANGE FOR CHEYENNE AND KIT CARSON COUNTIES IN COLORADO AND SHERMAN...WALLACE AND GREELEY COUNTIES IN KANSAS. HOWEVER...LIGHT WINDS ARE EXPECTED WHICH WILL REDUCE THE FIRE WEATHER DANGER FOR TOMORROW AFTERNOON. .LONG TERM...(SUNDAY THROUGH THURSDAY) ISSUED AT 1147 PM MST WED MAR 6 2013 SNOW WILL BE WINDING DOWN ON SUNDAY WITH ADDITIONAL ACCUMULATIONS OF LESS THAN AN INCH EXPECTED. HOWEVER...NORTHERLY WINDS WILL BE GUSTY AND RESULT IN AREAS OF BLOWING SNOW. SNOW WILL END BY SUNDAY NIGHT. THE REMAINDER OF THE PERIOD WILL BE DOMINATED BY UPPER RIDGING BUILDING ACROSS THE ROCKIES...RESULTING IN DRY CONDITIONS AND WARMING TEMPERATURES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1030 PM MST WED MAR 6 2013 POTENTIAL FOR OVERNIGHT FOG/STRATUS CONTINUES...WITH BEST CHANCES FOR REDUCTIONS IN FLIGHT CATEGORIES AT MCK. CONFIDENCE SOMEWHAT LOW ATTM THOUGH AS 00Z RAOBS AND RAP DATA LOWER CONFIDENCE IN HOW WIDESPREAD FOG POTENTIAL WILL BE. FOR THE TIME BEING...BROUGHT MCK DOWN TO MIDDLE OF THE ROAD/OPERATIONAL SIGNIFICANT MVFR FOR A PORTION OF THE OVERNIGHT HOURS. OTHERWISE...VFR CONDITIONS EXPECTED FOR THE REST OF THE PERIOD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...RRH LONG TERM...024 AVIATION...JRM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1032 PM MST WED MAR 6 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 218 PM MST WED MAR 6 2013 AS OF 3 PM CST...2 PM MST...SKIES WERE MOSTLY CLEAR TO PARTLY CLOUDY AS SOME HIGH LEVEL CIRRUS MOVES FROM WEST TO EAST. TEMPERATURES RANGED FROM THE LOW 40S NEAR NORTON...KANSAS TO NEAR 60 DEGREES IN TRIBUNE...KANSAS. WINDS WERE GENERALLY FROM THE SOUTHEAST AT 15 TO 20 MPH WITH GUSTS UP TO 25 OR 30 MPH. A LEE TROUGH WAS DEVELOPING ACROSS EAST CENTRAL COLORADO. FOR TONIGHT...BREEZY SOUTHEAST WINDS WILL WEAKEN THIS EVENING. WINDS WILL BACK TO THE EAST OVER THE EASTERN FORECAST AREA...ALLOWING AIR WITH HIGHER MOISTURE CONTENT TO FILTER INTO THE AREA. LOW TEMPERATURES WILL DROP INTO THE LOW 20S. WITH LIGHT WINDS...HIGHER DEWPOINTS AND COLD TEMPERATURES...FOG IS EXPECTED TO DEVELOP ACROSS A LARGE AREA TONIGHT. ACROSS THE WESTERN FORECAST AREA...A LEE TROUGH TO THE WEST WILL MOVE TO THE EAST. WINDS WILL BE LIGHT AND VARIABLE JUST EAST OF THE TROUGH AND FROM THE WEST OR NORTHWEST AT 5-10 MPH AS THE TROUGH MOVES IN. THIS SHOULD KEEP THE FOG FROM ADVANCING INTO EASTERN COLORADO. FOG COULD BE DENSE...BUT WAS NOT CONFIDENT ENOUGH TO PLACE THIS INTO THE FORECAST AT THE CURRENT TIME. TEMPERATURES WILL BE HIGHLY VARIABLE ACROSS THE FORECAST AREA FOR TOMORROW. HIGHS ACROSS MOST OF EASTERN COLORADO AND PORTIONS OF NORTHWEST KANSAS WILL BE IN THE MID 60S TO NEAR 70 IN SOME SPOTS. FOG AND CLOUDS WILL LINGER INTO THE LATE MORNING HOURS FOR NORTHEAST PORTIONS OF THE FORECAST AREA. THIS WILL KEEP HIGH TEMPERATURES CONFINED TO THE LOWER 50S NEAR MCCOOK NEBRASKA AND HILL CITY KANSAS. LIGHT AND VARIABLE WINDS IN THE MORNING WILL BECOME SOUTHEAST AT 10 TO 15 MPH DURING THE AFTERNOON HOURS. AT THIS TIME...FIRE WEATHER IS NOT EXPECTED TO BECOME A CONCERN FOR TOMORROW. RELATIVE HUMIDITIES WILL DROP INTO THE 15 TO 25 PERCENT RANGE FOR CHEYENNE AND KIT CARSON COUNTIES IN COLORADO AND SHERMAN...WALLACE AND GREELEY COUNTIES IN KANSAS. HOWEVER...LIGHT WINDS ARE EXPECTED WHICH WILL REDUCE THE FIRE WEATHER DANGER FOR TOMORROW AFTERNOON. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 205 PM MST WED MAR 6 2013 THURSDAY NIGHT-FRIDAY...UPPER LOW CENTER JUST OFF THE CALIFORNIA COAST AT THE BEGINNING OF THE PERIOD MOVING SOUTHEAST TOWARD THE SOUTHERN TIP OF CALIFORNIA/SOUTHWEST ARIZONA AREA BY 00Z SATURDAY. AT THE SURFACE LOW PRESSURE SLOWLY DEEPENS IN SOUTHEAST COLORADO THROUGH THE PERIOD. STRATUS/FOG EXPECTED ACROSS THE NORTHEAST 1/2 OF THE AREA MID THURSDAY NIGHT EXPANDING SOUTHWESTWARD BY 12Z FRIDAY AS WINDS TURN NORTHEAST IN RESPONSE TO DEEPENING LOW. STRATUS/FOG SHOULD RETREAT NORTH AND EAST FRIDAY AFTERNOON BUT COULD STILL POSE A PROBLEM ACROSS THE FAR EAST AND NORTHEAST WHERE BOUNDARY LAYER RH STILL HIGH. OTHERWISE SHOULD SEE AN INCREASE IN CLOUDINESS MOVING IN FROM THE SOUTHWEST AHEAD OF UPPER LOW. NOT TERRIBLY CONFIDENT IN PRECIPITATION CHANCES FRIDAY BUT ALSO CANT RULE IT OUT EITHER. HAVE KEPT SLIGHT CHANCE POPS GOING FOR NOW. THERE IS SOME INSTABILITY THAT MOVES IN FROM THE SOUTH DURING THE AFTERNOON AS WELL AS NOSE OF UPPER JET. WILL KEEP THUNDER MENTION GOING AS WELL. LOWS MID 20S TO LOW 30S WITH HIGHS LOW TO MID 50S NORTH OF I-70...UPPER 50S TO MID 60S SOUTH. FRIDAY NIGHT-SATURDAY...12Z GFS/NAM/09Z SREF BRING UPPER LOW OVER FORECAST AREA BY 00Z SUNDAY WITH 00Z ECWMF A BIT SLOWER OVER NORTH CENTRAL NEW MEXICO. FOR FRIDAY NIGHT MID LEVEL DRY SLOT TRIES TO WORK ITS WAY INTO THE AREA AFTER MIDNIGHT WITH BETTER PRECIPITATION CHANCES GENERALLY NORTH OF INTERSTATE 70 AND BETTER ALONG THE NEBRASKA/KANSAS BORDER. PREVIOUS FORECAST HAD THE GENERAL IDEA JUST TWEAKED POPS DOWN A BIT WHERE CONFIDENCE HIGHER IN WHERE DRY SLOT WOULD BE. STRATUS/FOG WILL BE A CONCERN AS WELL AND ADDED TO FORECAST. UPPER JET OVER THE AREA WITH GOOD DIVERGENCE. STILL SOME WEAK INSTABILITY OVER THE AREA SO HAVE ALSO KEPT SMALL CHANCE FOR THUNDERSTORMS. FOR SATURDAY SFC LOW MOVES INTO CENTRAL OR SOUTHWEST KANSAS DEPENDING ON THE MODEL CHOICE. DRY SLOT WORKS ITS WAY EAST LIMITING PRECIP POTENTIAL WHILE FURTHER WEST/NORTHWEST WRAPAROUND PRECIPITATION MOVES IN. LOWERED POPS A BIT WHERE DRY SLOT EXPECTED BUT WITH DIFFERENCES IN OPINION MODEL WISE DIDNT GET TOO SPECIFIC AS CONFIDENCE NOT TERRIBLY HIGH. DEFINING RAIN/SNOW LINE ALSO DEPENDENT ON SFC LOW LOCATION AND EXTENT OF WRAPAROUND PRECIP. AGAIN WILL TRY AND BLEND MODEL SOLUTIONS FOR NOW. LOW TEMPERATURES MILD IN THE MID 30S TO MID 40S. HIGHS SATURDAY LOW 40S FAR NORTHWEST...50-60 ELSEWHERE...WARMEST FROM HILL CITY TO LEOTI. SATURDAY NIGHT-SUNDAY NIGHT...MODELS COMING INTO BETTER AGREEMENT. UPPER LOW EXPECTED TO MOVE SLOWLY EAST/NORTHEAST AS UPPER RIDGE BUILDS IN FROM THE WEST. BEST CHANCE OF ACCUMULATING SNOW LOOKS TO BE SATURDAY NIGHT AS COLDER AIR MOVES IN FROM THE WEST/NORTHWEST ON THE BACKSIDE OF THE LOW. NORTH WINDS WILL ALSO INCREASE PRODUCING SOME BLOWING SNOW AND REDUCED VISIBILITIES. ON SUNDAY SNOW WILL DECREASE FROM WEST TO EAST AND SHOULD BE OUT OF THE AREA SUNDAY NIGHT. LOWS SATURDAY NIGHT IN THE MID 20S TO LOW 30S...FALLING INTO THE UPPER TEENS TO LOW 20S SUNDAY NIGHT. HIGHS SUNDAY IN THE 30S. MONDAY-WEDNESDAY...WARMING TREND COMMENCES WITH SLIGHTLY BELOW NORMAL TEMPERATURES MONDAY AND ABOVE NORMAL TEMPERATURES TUESDAY AND WEDNESDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1030 PM MST WED MAR 6 2013 POTENTIAL FOR OVERNIGHT FOG/STRATUS CONTINUES...WITH BEST CHANCES FOR REDUCTIONS IN FLIGHT CATEGORIES AT MCK. CONFIDENCE SOMEWHAT LOW ATTM THOUGH AS 00Z RAOBS AND RAP DATA LOWER CONFIDENCE IN HOW WIDESPREAD FOG POTENTIAL WILL BE. FOR THE TIME BEING...BROUGHT MCK DOWN TO MIDDLE OF THE ROAD/OPERATIONAL SIGNIFICANT MVFR FOR A PORTION OF THE OVERNIGHT HOURS. OTHERWISE...VFR CONDITIONS EXPECTED FOR THE REST OF THE PERIOD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...RRH LONG TERM...99 AVIATION...JRM
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1216 PM EST THU MAR 07 2013 ...Updated Aviation Discussion... .Forecast Update... Issued at 1059 AM EST Wed Mar 5 2013 Morning satellite imagery shows widespread low clouds across the forecast area this morning. Combination of inversion aloft along with light winds will keep the low clouds socked in for much of the day. Some very light drizzle and snow flurries will be possible in areas throughout the day as well. With the expected cloud cover to persist, have adjusted temperatures down several degrees to account for the loss of solar insolation. Highs probably will only top out in the lower 30s in the east with mid to upper 30s across the central and west. Updated forecast products are in production and will be available shortly. && .Short Term (Now - Friday)... Issued at 305 AM EST Thu Mar 7 2013 Although a few flurries or instances of drizzle aren`t out of the realm of possibilities this morning, believe most areas should be dry through the short term period. Sfc high pressure and upper level ridging will work into the area through Friday. The main short term challenges will be the exit of low level stratus this afternoon/evening and temperatures. For today, think that the morning hours will remain cloudy. Latest model runs keep pushing back the erosion of stratus across the area which makes sense...thick stratus is stubborn to erode in most cases. Thus, think that south central KY may see some sunshine by mid afternoon, but southern Indiana and north central KY will stay cloudy for much of the day. For the northern portions of the area, clouds will likely erode sometime this evening from SW to NE. Tonight and Friday should be mostly clear or only partly cloudy. As for temperatures, think that low clouds will prohibit much of a diurnal rise today except for maybe in south central KY where stratus is expected to become more scattered in nature. Thus, have gone below guidance for high temps over much of the area today. A good temp gradient will likely set up along the edge of the stratus deck which will be tough to nail down. Highs should range from the upper 30s to mid 40s from NE to SW. For tonight, think we`ll see good cooling with light northeasterly winds and clear skies in place. Low temps should fall into the low to mid 20s. Friday will feature plenty of sunshine and temperatures warming into the upper 40s and lower 50s. .Long Term (Friday Night through Wednesday)... Issued at 315 AM EST Thu Mar 7 2013 Friday Night - Saturday Night... Upper level ridge axis will be directly overhead Friday night, with surface high pressure anchored over the eastern Great Lakes. These two features will slide east, albeit slowly due to downstream blocking, through the majority of the weekend. This will set the stage for a dry and much milder period of weather. Friday night lows will be slightly below normal for this time of year due to good radiational cooling conditions, however temperatures will quickly recover on Saturday into the upper 50s and low 60s across the region. Saturday Night will feature much milder lows as steady southerly flow sets in between high to our east and the next developing storm system to our west. Lows will only drop to the 40-45 degree range. One thing worth noting, is that models have sped up with respect to first wave of warm advection rainfall around dawn on Sunday. Will leave western fringes dry for now, but may eventually have to introduce small chances of measurable rain very late in the period Saturday night due to the isentropic lift regime that will be in place. Sunday - Tuesday... By Sunday, upper level ridge axis will be along the Atlantic Coast with split upper level flow across the western two-thirds of the CONUS. Broad southwest flow aloft will develop over the region between ridging to our east and troughing over the SW CONUS, with elongated surface trough/boundary just to our west. The trend has continued to be faster with precipitation arrival on Sunday, however confidence is not all that high due to split upper level flow and general inconsistency in model performance to this point. Don`t want to totally buy into how fast models are with the system yet due to the downstream blocking, and tendency for more amplified/slower overall progression of systems. Nevertheless, have introduced 30-40 percent chances of rain mainly across southern Indiana for Sunday. Sunday will continue the warming trend as steady southerly flow persists and temperatures jump into the low and mid 60s, however will stay away from the warmest guidance as increasing cloud cover and perhaps some precipitation will keep temps down slightly. Periodic rain will be likely for Sunday night and Monday as a couple of waves ride along a slowly eastward progressing boundary oriented nearly parallel to the upper level flow. Could end up getting a pretty decent amount of rainfall as the system will be slow and PWATS up around 1.25" through the column overspread the region. Will continue to leave thunder out as thermal profiles are moist adiabatic at best, however will continue to monitor. The frontal boundary looks to move through by Monday afternoon/evening with precipitation beginning to taper off Monday night. Will only keep lingering pops in the east on Tuesday. Still keeping any snow mention out of the forecast as cold air does not look to catch up to deep moisture in time, but this will be another portion of the forecast that needs continued monitoring. Lows Monday and Tuesday nights will be in the mid and upper 30s, with highs on Tuesday and Wednesday in the upper 40s to around 50. && .Aviation (18Z TAF Issuance)... Issued at 1215 PM EST Thu Mar 7 2013 Main TAF issue through the period will be the lingering low-level stratus deck across the region. Strong capping inversion aloft is keeping the low-level moisture locked in place. While the latest NAM and GFS runs are suggestive of the clouds scouring out this afternoon, it seems more likely that it will be later tonight before things clear out in earnest. Given that the RAP model seems to have a pretty good handle on things, plan on leaving the MVFR cigs in the forecast for this afternoon and a good part of the evening and into the overnight period. It is very possible that we may not scour out to VFR until Friday morning. However, we`ll continue to look at future datasets and adjust the forecast as necessary. Winds will be light across the region and out of the north and northwest. Winds will gradually shift to the northeast tonight and remain light. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Update...........MJ Short Term.......AMS Long Term........BJS Aviation.........MJ
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1226 AM EST THU MAR 7 2013 .SYNOPSIS... LOW PRESSURE MOVES FURTHER OUT TO SEA THIS MORNING. HIGH PRESSURE BUILDS INTO THE AREA THIS AFTERNOON INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... INTENSE LOW PRS CONTS TO MOVE FRTR OFFSHORE ATTM. ONLY PCPN LEFT WAS ALONG THE IMMEDIATE COASTS WITH A MIX OF RAIN/SNOW SHWRS. LATEST DATA SHOWING M CLR SKIES W OF I95. DESPITE GUSTS OVR 30 MPH ALONG THE COASTS...WNDS HAVE DMNSHD BELOW WND ADVSRY CRITERIA PAST FEW HRS SO HAVE DROPPED THE ADVSRY ALL CSTL AREAS XCPT AT ORF/VA BCH/CURRITUCK NC WHERE GUSTS AOA 40 KTS CONT. LOWS U20S-M30S. && .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY/... LO PRES CONTS TO MOVE OUT TO SEA THU THROUGH SAT. A SECOND S/W DIVING SSE FM WRN NEW ENG/NY STATE ON FRI PSBLY RESULTING IN BKN/OVC CLDNS (ESP E OF I 95) AND ISOLD/SCT PCPN. NNW WINDS WILL RMN GUSTY AS WELL...ESP NR THE CST...THROUGH FRI. SFC HI PRES IS SLO TO BUILD SWD INTO THE MDATLC RGN BY SAT...FINALLY RESULTING IN DRY WX FOR ALL AREAS. P/MCLDY TNGT...THEN PCLDY OR VRB CLDNS THU. PCLDY W/MCLDY E THU NGT THROUGH FRI...THEN MSTLY SKC ON SAT. HI TEMPS RANGING THROUGH THE 40S N AND CNTRL AREAS...TO L50S S THU/FRI...THEN FM THE U40S TO M50S SAT. LO TEMPS IN THE U20S TO L30S THU/FRI NGTS. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... GOING WITH A COMBINATION OF THE 12Z GFS/ECMWF FOR THE EXTENDED PERIOD...ESPLY WITH REGARD TO TIMING OF APPROACH AND PASSAGE OF COLD FRONT MON NGT THRU TUE. UA RDG/LRG AREA OF SFC HI PRES WILL PROVIDE DRY WX SAT NGT INTO MON MORNG. LO PRES AND ASSOC COLD FRONT WILL THEN AFFECT THE REGION MON EVENG THRU TUE...WITH DECENT CHC FOR SHOWERS. MILDER TEMPS EXPECTED SUN INTO TUE. DRY WX RETURNS FOR TUE NGT THRU WED...AS HI PRES WILL GRADUALLY BLD IN FM THE NW. MIN TEMPS WILL BE IN THE LWR TO MID 30S SUN MORNG...IN THE UPR 30S TO LWR 40S MON MORNG...IN THE 40S TUE MORNG...AND IN THE MID 30S TO ARND 40 WED MORNG. MAX TEMPS WILL BE IN THE MID 50S TO LWR 60S SUN...IN THE LWR TO MID 60S MON...IN THE MID 50S TO LWR 60S TUE...AND IN THE MID TO UPR 50S WED. && .AVIATION /05Z THURSDAY THROUGH MONDAY/... LOW PRESSURE HAS MOVED OFF THE VA/NC COAST AND STRONG WINDS ARE GUSTING FROM THE N/NNW AT ALL TAF SITES. GUSTS TO 40-45 KT REMAIN PSBL AT TIMES THROUGH THE OVERNIGHT HOURS...ESPECIALLY ALONG THE COAST. RAIN AND SNOW WILL TAPER OFF TONIGHT. CIGS AND VSBYS WILL CONTINUE TO BE IN AND OUT OF IFR CONDS WITH MAINLY IFR ON THE BACKSIDE OF THE LOW. PCPN ENDS AND DRYING WILL ALLOW CIGS TO IMPROVE AFT 05Z. VFR CONDS ARE EXPECTED TOWARD MORNING WITH WINDS GUSTING TO 25KT IN THE AFTN. THE LOW WILL CONTINUE TO SLOWLY PUSH OFFSHORE ALLOWING HIGH PRESSURE TO BUILD IN FROM THE NW. FAIR WEATHER/VFR CONDITIONS WILL PREVAIL INTO EARLY NEXT WEEK WITH GUSTY WINDS CONTINUING DUE TO THE STRONG PRESSURE GRADIENT THAT WILL REMAIN OVER THE AREA. && .MARINE... UPDATE: HAVE HOISTED STORM WARNING FOR ATLANTIC COASTAL WATERS NORTH OF VA/NC BORDER. HAVE BEEN HANDLING WITH SPECIAL MARINE WARNINGS THUS FAR, BUT WITH HRRR SHOWING THIS SURGE LASTING A FEW HOURS LONGER, FEEL A BIT MORE COMFORTABLE HOISTING STORM HEADLINE THROUGH 2AM, WITH A PERIOD OF GALES LIKELY AFTER WINDS DIMINISH SOME AFTER MIDNIGHT. OTHERWISE, HAVE DROPPED GALES OVER THE RIVERS TO SCA...IN EFFECT UNTIL MORNING. PREVIOUS DISCUSSION.... A STRENGTHENING SFC LOW PRESSURE WILL ROTATE OVER THE MID ATLANTIC COAST THIS EVENING...THEN PUSH OUT TO SEA OVERNIGHT. WIND DIRECTIONS ARE PRIMARILY N LATE THIS AFTN AND WILL BECOME MORE NWLY AS THE EVENING PROGRESSES. A NRLY SURGE HAS BEGUN OVER NRN CHES BAY AND WILL CONTINUE TO PUSH SWD THROUGH THE EVENING. CURRENT FORECAST ALREADY HAS THIS TREND IN PLACE. FOR COASTAL WATERS N OF CHINCOTEAGUE...A STORM WARNING HAS BEEN ISSUED THROUGH EARLY THU MORNING AS THE NRLY SURGE COMMENCES LATE THIS AFTN INTO THE EVENING AND GUSTS REACH 50-55 KT. IN ADDITION...GALE WARNINGS HAVE BEEN ISSUED FOR THE RIVERS TO ACCOUNT FOR THE NRLY SURGE AND FOR WHEN WINDS BECOME NWLY...WHICH IS A FAVORABLE ORIENTATION FOR STRONG WINDS TO OCCUR. GALES ARE EXPECTED TO FALL BELOW 34 KT AT VARIOUS TIMES TONIGHT AND THU MORNING...AND WILL BE REPLACED BY SOLID SCA FLAGS AS DEEMED NECESSARY. SEAS ARE ANYWHERE FROM 10-19 FEET N OF CAPE CHARLES AND 5-9 FT S OF CAPE CHARLES. THEY SHOULD STAY ELEVATED THROUGH THU MORNING AND THEN FALL VERY SLOWLY THROUGH THE REST OF THE WEEK. AS THE SFC LOW PUSHES EAST OF LONGITUDE 70W LATE THU NIGHT INTO FRI...THE PRESSURE GRADIENT REMAINS TIGHT AND A SECONDARY SHORTWAVE FEATURE MOVES SE ACROSS THE WATERS. THIS FEATURE WILL BRING A REINFORCING SHOT OF COLD AIR INTO THE REGION AND THE SUBSEQUENT CAA WILL PRODUCE ANOTHER ROUND OF SOLID SCA CONDITIONS (POSSIBLY GALES OVER COASTAL WATERS) THU NIGHT INTO FRI MORNING. WINDS THEN SHIFT TO THE N FRI NIGHT AND HIGH PRESSURE BEGINS TO BUILD INTO THE AREA FROM NW...BRINGING MORE QUIET CONDITIONS TO AREA WATERS THROUGH THE WEEKEND. && .TIDES/COASTAL FLOODING... UPDATE...COASTAL FLOOD WARNING HAS BEEN UPDATED TO RUN THROUGH EARLY FRIDAY OVER ALL COASTAL AREAS NORTH OF VA/NC BORDER, WITH THE EXCEPTION OF LANCASTER/NORTHUMBERLAND COUNTIES, WHERE SLIGHTLY LOWER WATER LEVELS NECESSITATES ONLY AN ADVISORY. TIDAL DEPARTURES ON THE ORDER OF 2.5 TO 4 FT ABOVE NORMAL HAVE LED TO MODERATE COASTAL FLOODING IMPACTS ALREADY OVER MUCH OF THIS AREA, WITH ADDITIONAL ANOMALIES EXPECTED TONIGHT AND OVERNIGHT. MDL AND CBOFS GUIDANCE HAVE BOTH UNDERESTIMATED THIS NORTHERLY SURGE THIS EVENING, AND HAVE SIDED CLOSE TO/JUST ABV VIMS GUIDANCE FOR THIS PACKAGE, AS IT APPEARS TO BE THE MOST ACCURATE IN DEPICTING TIDAL LEVELS OCCURRING RIGHT NOW. THIS GUIDANCE INDICATING ANOTHER TIDE CYCLE BETWEEN 2.5 TO 4 FT ABOVE NORMAL (HIGHEST ALONG MD EASTERN SHORE). IF THIS GUIDANCE COMES TO FRUITION...MODERATE TO SEVER COASTAL FLOODING IMPACTS ARE EXPECTED AT OCEAN CITY INLET, WITH WIDESPREAD MODERATE COASTAL FLOODING EXPECTED ON WESTERN SHORE OF CHES BAY SOUTH OF NEW PT COMFORT DURING THE THU MORNING HIGH TIDE. SEE CFWAKQ FOR SITE SPECIFIC DETAILS. UNFORTUNATELY, THE SLOW MOVEMENT OF THE SFC LOW WILL KEEP POSITIVE TIDAL ANOMALIES THROUGH FRIDAY. AND WHILE THE TIDE CYCLE THURSDAY NIGHT APPEARS TO BE CLOSER TO MINOR, THE HIGHER ASTRONOMICAL TIDE FOR FRIDAY MORNING COULD APPROACH MODERATE CCOASTAL FLOODING IMPACTS YET AGAIN. SUBSTANTIAL IMPROVEMENT IS EXPECTED LATER FRIDAY AND ESPECIALLY ON SATURDAY. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...COASTAL FLOOD WARNING UNTIL 7 AM EST FRIDAY FOR MDZ024-025. NC...WIND ADVISORY UNTIL 9 AM EST THIS MORNING FOR NCZ017-102. VA...COASTAL FLOOD WARNING UNTIL 7 AM EST FRIDAY FOR VAZ084>086-091- 094>096-098>100. WIND ADVISORY UNTIL 9 AM EST THIS MORNING FOR VAZ095-098. COASTAL FLOOD ADVISORY UNTIL 7 AM EST FRIDAY FOR VAZ077-078. MARINE...STORM WARNING UNTIL 2 AM EST EARLY THIS MORNING FOR ANZ652-654- 656. STORM WARNING UNTIL 5 AM EST EARLY THIS MORNING FOR ANZ650. GALE WARNING UNTIL 7 AM EST FRIDAY FOR ANZ658. SMALL CRAFT ADVISORY UNTIL 7 AM EST THIS MORNING FOR ANZ635>637. GALE WARNING UNTIL 7 AM EST THIS MORNING FOR ANZ630>634-638. && $$ SYNOPSIS...MPR NEAR TERM...MPR SHORT TERM...ALB LONG TERM...BMD AVIATION...DAP/LSA MARINE...BMD/MAM TIDES/COASTAL FLOODING...AKQ
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
625 PM EST FRI MAR 8 2013 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 431 PM EST FRI MAR 8 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW DOMINATING NAMERICA. IN THE SRN STREAM...POTENT LOOKING SHORTWAVE HAS MOVED ONSHORE OVER SRN CA WHILE ANOTHER WAVE IS DROPPING S OVER WRN OR/NRN CA. BOTH OF THESE WAVES WILL PLAY A ROLE IN THE WX ACROSS THE GREAT LAKES IN THE COMING DAYS. DOWNSTREAM OF THE WRN TROF...RIDGING IS OVER THE CNTRL CONUS. TO THE N...ONE SHORTWAVE IS TRACKING THRU NRN ONTARIO. ANOTHER WAVE IS DROPPING SE INTO ALBERTA ON THE PERIPHERY OF POLAR VORTEX CENTERED JUST N OF HUDSON BAY. THIS WAVE WILL ALSO PLAY A ROLE IN THE WX OVER THE GREAT LAKES IN THE COMING DAYS. CLOSER TO HOME...LOW CLOUDS HAVE LINGERED OVER THE ERN FCST AREA IN SRLY FLOW OFF LAKE MI. HOWEVER...RECENTLY...ONLY A SMALL AREA OF STRATOCU REMAINS...STREAMING ONSHORE IN SRN SCHOOLCRAFT COUNTY. ELSEWHERE...EARLY MARCH SUNSHINE IS DOING ITS JOB ON THE LOWER ALBEDO FORESTED LAND OF THE U.P. TEMPS HAVE PUSHED INTO THE 40S AT A NUMBER OF OBS SITES OVER WRN UPPER MI. IN THE SHORT TERM...QUIET WX TONIGHT WILL GIVE WAY TO INCREASING PCPN CHANCES SAT UNDER STRENGTHENING WAA REGIME AHEAD OF NRN STREAM WAVE THAT WILL BE MOVING INTO SRN MANITOBA/ND AND SRN STREAM WAVE EMERGING OVER THE SRN HIGH PLAINS. TONIGHT...SRLY FLOW WILL BE ON THE INCREASE AHEAD OF THE AFOREMENTIONED SHORTWAVES. THERE IS THE USUAL CONCERN UNDER SRLY FLOW THAT LOW CLOUDS MAY DEVELOP. IN THIS CASE...HOWEVER...THE NAM AND GFS SHOW DRY AIR ADVECTION TONIGHT AT THE LOW-LEVELS AS TRAJECTORIES STILL HAVE SUFFICIENT COMPONENT EMANATING FROM RETREATING HIGH PRES. SO...LOW CLOUDS MAY NOT REALLY BE AN ISSUE TONIGHT. IF ANY VERY LOW/SHALLOW STRATUS DOES DEVELOP... IT SHOULD ONLY BE IN THE AREAS WITH BEST UPSLOPING OVER CNTRL UPPER MI. OTHERWISE...EXPECT GENERALLY PARTLY CLOUDY SKIES IN THE EVENING...AND THEN AN INCREASE IN HIGH CLOUDS OVERNIGHT. TYPICAL FOR THIS TYPE OF INITIALLY RATHER WEAK SRLY FLOW...EXPECT LOWEST MINS NEAR THE BAY OF GREEN BAY AS ICE COVER ENHANCES COOLING AND STRENGTHENS NOCTURNAL INVERSION IN THAT AREA. LOWS SHOULD BE AROUND 20F THERE. ON SAT...UNDER STRONG WAA AND ISENTROPIC ASCENT (295K SFC)...EXPECT PCPN TO DEVELOP FROM W TO E AS LOW-LEVEL DRY AIR IS EVENTUALLY OVERCOME. TRAJECTORIES SUGGEST THERE WILL BE SOME MAINTENANCE OF THE LOW-LEVEL DRY AIR OVER THE E EVEN AS FORCING AND RESULTING PCPN ALOFT OVERSPREAD THAT AREA. SO...POPS WILL SHOW A GRADIENT FROM CATEGORICAL W TO JUST CHC E LATE. IT`S QUITE POSSIBLE THE E MAY NOT SEE ANY PCPN SAT. AS FOR PTYPE...IT`S A CHALLENGE AS IT ALMOST ALWAYS IS WHEN IT`S NOT COLD ENOUGH FOR JUST SNOW OR WARM ENOUGH FOR JUST RAIN. THERE WILL BE THE USUAL BATTLE BETWEEN STRONG WAA AND THE COOLING IT GENERATES THRU ASCENT AS WELL AS EVAPORATIVE COOLING EARLY ON. BELIEVE THE EVAPORATIVE COOLING EARLY ON WILL LEAD TO PREDOMINANTLY SNOW AS THE PTYPE INITIALLY. THEREAFTER...FCST SOUNDINGS SHOW PROFILE GENERALLY HOVERING AROUND 0C IN THE LOWER LEVELS...FLUCTUATING BASED ON ASCENT/PCPN INTENSITY. MEANWHILE...THE NEAR SFC LAYER MAY RESPOND A LITTLE TO DAYTIME HEATING...PUSHING THE ODDS TOWARD RAIN. AT THIS POINT...WILL INCLUDE SNOW AS THE GENERAL PREVAILING PTYPE IN MOST AREAS WITH A MENTION OF RAIN. INCLUDED FZRA AS WELL WHERE TEMPS ARE AROUND FREEZING. IF THERE IS FZRA...IT SHOULD BE CONFINED TO THE MORNING/EARLY AFTN BEFORE SURFACES RESPOND TO WEAK DAYTIME HEATING. WITH TEMPS PUSHING INTO THE MID 30S... WET/SLUSHY SNOW ACCUMULATIONS WILL BE MINOR...MAYBE AROUND AN INCH. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 431 PM EST FRI MAR 8 2013 SATURDAY NIGHT... THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE EVOLUTION OF THE SYOPTIC PATTERN WITH A PROGRESSIVE PATTERN AND LITTLE PHASING BETWEEN THE NRN STREAM MID LEVEL TROUGH MOVING THROUGH NRN ONTARIO AND THE NRN GREATLAKES AND THE SRN STREAM SHORTWAVE MOVING EAST FROM THE PLAINS. ABUNDANT MOISTURE INFLOW WITH MODERATE TO STRONG 285K-300K ISENTROPIC LIFT AND A PERIOD OF 700-600 MB FGEN SHOULD SUPPORT A BAND OF PCPN THROUGH THE CWA...ESPECIALLY BTWN 00Z-06Z WITH QPF AMOUNTS TO AROUND 0.25 INCH. CONFIDENCE IS ALSO HIGHER THAT A SIGNIFCANT (1C TO 3C) WARM LAYER WILL SPREAD THROUGH MOST OF THE CWA GIVEN STRONG WAA WITH SW 40-45 KT 850 MB WINDS BY 00Z/SUN. GENERALLY UTILIZED NAM/GEM LOW LEVEL THERMAL PROFILE TO DELINEATE PCPN TYPE PATTERN. WITH ENOUGH WARMTH LINGERING FROM DAYTIME HEATING...ANY SFC COLD LAYER WILL BE LESS PRONOUNCED LIMITING POTENTIAL FOR FZRA. SO...MAINLY RA/SN MIX EXPECTED WITH THE GREATEST SNOW CHANCES OVER THE WEST HALF. WITH LOW SLR AOB 10/1...ANY WET SNOWFALL AMOUNTS SHOULD ONLY AMOUNT TO AN INCH OR TWO AT MOST. SUNDAY...THERE WERE GREATER MODEL DIFFERENCES AS THE GFS ALLOWS ANOTHER DEFORMATION BAND OF PCPN TO LIFT INTO UPPER ASSOCIATED WITH THE SRN STREAM SHRTWV. SINCE THE GLOBAL GEM/ECMWF CONTINUE TO SHOW A MORE PROGRESSIVE SOLUTION...THE FCST CONTINUES WITH THE IDEA OF TAPERING OFF POPS/QPF FROM WEST TO EAST WITH MAINLY JUST CHANCE POPS BY AFTERNOON. SOME LAKE ENHANCED SNOW MAY DEVELOP BUT WITH THE SYNOPTIC SCALE UPWARD MOTION AND DEEPER MOISTURE DEPARTING...ANY AMOUNTS SHOULD BE LIGHT. SUN NIGHT INTO MON...850 MB TEMPS DROPPING INTO THE -12C TO -14C ALONG WITH CONTINUED CYCLONIC NRLY FLOW COULD STILL SUPPORT SOME LES. HOWEVER...WITH STRONG 850-700 MB DRYING...ANY AMOUNTS ARE EXPECTED TO BE LIGHT TUE-FRI...MDLS WERE CONSISTENT WITH A WEAK CLIPPER SHORTWAVE AND SFC TROUGH MOVING THROUGH THE UPPER GREAT LAKES MON NIGHT INTO TUE. THE FAVORED ECMWF REMAINED MORE AMPLIFIED WITH THE ERN GREAT LAKES TROUGH BY WED WITH COLDER AIR AVAILABLE FOR SOME NW FLOW LES COMPARED TO THE THE GFS. CONFIDENCE IN DETAILS DROPS OFF BY THU-FRI WITH REGARD TO THE POSITION/STRENGTH OF THE NEXT SHORTWAVE THAT COULD BRING SNOW CHANCES INTO THE REGION. TEMPS SHOULD REMAIN AT OR BELOW SEASONAL AVERAGES. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 622 PM EST FRI MAR 8 2013 EXPECT VFR CONDITIONS TO PREVAIL THRU TNGT WITH S WIND ON THE WRN FLANK OF HI PRES IN LOWER MI AND DRYNESS OF UPSTREAM AIRMASS TO THE S. THE ONLY EXCEPTION MIGHT BE AT SAW WITH AN UPSLOPE FLOW DOWNSTREAM OF AN AREA OVER SCENTRAL UPR MI WHERE RADIATIONAL COOLING MIGHT BE ENHANCED ENUF TO RESULT IN SOME LO CLDS/FOG. MAINTAINED MENTION OF SCT LO CLDS TO REFLECT THIS POTENTIAL THAT WOULD LINGER JUST PAST SUNRISE ON SAT. THEN AN APRCHG LO PRES TROF WL BRING AN INCRSG THREAT OF SOME SN OR MIXED RA/SN DURING THE LATE MRNG/AFTN ON SAT. LINGERING LLVL DRYNESS WL SLOW DOWN THE ONSET OF LOWER CIGS/VSBY...BUT THESE CONDITIONS SHOULD DVLP WITH PERSISTENT PCPN/MOISTENING. THE BEST SHOT AT IFR WX WL BE AT CMX...FARTHER FM DEPARTING LLVL DRY AIR AND WHERE NEAR SFC SE FLOW WL UPSLOPE. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 431 PM EST FRI MAR 8 2013 SOUTHERLY FLOW WILL DOMINATE TONIGHT THRU SAT EVENING AHEAD OF AN APPROACHING LOW PRES TROF. TYPICAL FOR SOUTHERLY FLOW...STRONGEST WINDS WILL BE OVER ERN LAKE SUPERIOR...REACHING UPWARDS OF 30KT SAT AFTN/EVENING. TROF WILL THEN PASS ACROSS LAKE SUPERIOR LATE SAT NIGHT/SUN...BRINGING A SHIFT TO 20-30KT NW WINDS. WINDS WILL THEN SLOWLY SUBSIDE LATE SUN NIGHT/MON...FALLING TO UNDER 15KT FOR MON NIGHT/TUE. MAY SEE A SLIGHT INCREASE IN WINDS WED. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...JLB AVIATION...KC MARINE...JLB
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1235 PM EST THU MAR 7 2013 .SYNOPSIS... ISSUED AT 328 AM EST THU MAR 7 2013 LAKE SHORE AREAS WILL SEE OCCASIONAL FLURRIES OR LIGHT SNOW TODAY...OTHERWISE IT WILL BE PARTLY TO MOSTLY CLOUDY WITH TEMPERATURES IN THE 30S. DRY WEATHER IS EXPECTED FOR FRIDAY AND MUCH OF SATURDAY. TEMPERATURES WILL WARM TO AROUND 40 ON FRIDAY AND INTO THE 40S FOR SATURDAY. A RATHER UNSETTLED PERIOD IS EXPECTED LATE IN THE WEEKEND AND INTO EARLY NEXT WEEK. RAIN IS EXPECTED BY LATE SATURDAY OR SATURDAY NIGHT AND CONTINUING INTO SUNDAY. THE PRECIPITATION MAY CHANGE TO SNOW...OR A MIX OF RAIN AND SNOW SUNDAY NIGHT THROUGH MONDAY NIGHT...AS TEMPERATURES COOL FOR NEXT WEEK. && .UPDATE... ISSUED AT 1046 AM EST THU MAR 7 2013 I DECREASED CLOUD COVER FOR THE REMAINDER OF THE DAY. MANY OF THE CLOUDS THAT WERE AROUND THIS MORNING HAVE CONTINUED TO ERODE AND EXIT TO EAST. CLEARING WILL CONTINUE FROM WEST TO EAST THIS AFTERNOON AND THIS IS SHOWN BY THE NAM AND RAP MODEL SUGGESTIONS. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 328 AM EST THU MAR 7 2013 A SMALL AREA OF LAKE EFFECT SNOW SHOWERS/FLURRIES WAS CLIPPING WESTERN VAN BUREN COUNTY THIS MORNING. EXPECT THIS MAY LINGER MUCH OF TODAY AS COLD ADVECTION PEAKS AROUND MID DAY. THE FLOW REMAINS 330-350 SO ONLY THE LAKE SHORE WILL EXPERIENCE OCCASIONAL FLURRIES OR LIGHT SNOW. IT COULD RESULT IN A LIGHT DUSTING IN SOME LOCALES. INLAND AREAS SHOULD SEE A MIX OF CLOUDS AND SUN...WITH THE CLOUDS MORE FREQUENT THAN SUN. SLIGHTLY COOLER THAN YESTERDAY WITH MOSTLY LOW AND MID 30S FOR HIGHS. UPPER RIDGING MOVES FOR THE END OF THE WORK WEEK. ALONG WITH THIS WILL COME WARM ADVECTION. ANY LAKE SNOW SHOULD END BY THIS EVENING ON THE HEELS OF THE WARM ADVECTION. SKIES SHOULD GRADUALLY CLEAR LEADING TO A MOSTLY SUNNY FRIDAY WITH TEMPS APPROACHING 40. CLOUDS SHOULD THICKEN THROUGH SATURDAY WITH WARM ADVECTION CLOUDS AND AN INCREASING GULF MOISTURE FLOW. THE WARM FETCH WILL PUSH TEMPS WELL INTO THE 40S. WE MAY SEE A FEW RAIN SHOWERS TOWARD SATURDAY EVENING AS THE LOW LEVELS MOISTEN AHEAD OF A SYSTEM DEVELOPING OVER THE CENTRAL PLAINS. .LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 328 AM EST THU MAR 7 2013 SCATTERED TO NUMEROUS RAIN SHOWERS ARE EXPECTED SATURDAY NIGHT AND SUNDAY AS A WARM AIR ADVECTION PATTERN IMPACTS THE REGION. 40 TO 50 KT SOUTHERLY LOW LEVEL JET IS PROGGED OUT AHEAD OF AN APPROACHING FRONTAL BOUNDARY... WITH NARROW CORRIDOR OF PWATS AROUND ONE INCH STREAMING NORTH. WILL NOT INCLUDE THUNDER AT THIS POINT... BUT WILL HAVE TO WATCH FOR THAT POSSIBILITY. MODELS ARE STILL STRUGGLING WITH TIMING/STRENGTH OF JET STREAK ENERGY EJECTING NORTHEAST FROM THE FOUR CORNERS REGION... BUT IT DOES LIKE A STRONG SHORTWAVE WILL BE MOVING INTO IOWA AROUND 12Z SUNDAY. CURRENT MODEL SOLUTIONS IMPLY THAT THE SHORTWAVE MOVING NEWD FROM THE CENTRAL PLAINS REGION ON SUNDAY WILL WEAKEN AND SHEAR OUT AS IT COMES INTO MI AND GETS ABSORBED IN WITH AN APPROACHING NRN STREAM TROUGH. THE SFC FRONTAL BOUNDARY ALSO WEAKENS BUT DOES SLIP THROUGH THE ENTIRE CWFA BY 12Z MONDAY. MODELS HAVE BEEN VERY INCONSISTENT IN REGARDS TO WHAT HAPPENS AFTER THAT... BUT CONTINUE TO SUGGEST THE POSSIBILITY OF ANOTHER WAVE MOVING MOVING NORTHEAST ALONG THE SFC FRONT EARLY NEXT WEEK. PRECIP TYPE REMAINS PROBLEMATIC... SINCE IF THE FRONT GETS HUNG UP THEN THE LOW LEVEL COLD AIR MAY HAVE A TOUGH TIME FILTERING INTO THE REGION FROM THE NORTH. DESPITE THE MODEL INCONSISTENCIES FOR EARLY NEXT WEEK... ALL SOLUTIONS SEEM TO EVENTUALLY CONVERGE ON A RATHER CHILLY PATTERN BY MID WEEK WITH TROUGHING AND COLD AIR ALOFT. THIS WOULD LEAD TO SCATTERED SNOW OR MIXED RAIN AND SNOW SHOWERS AND HIGHS IN THE 30S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1235 PM EST THU MAR 7 2013 CONFIDENCE IS HIGH THAT VFR CONDITIONS WILL PREVAIL THROUGH THIS EVENING. CEILINGS IN THE 3000-4000 FT AGL RANGE SHOULD SLOWLY RISE THIS AFTERNOON AND MAY EVEN SLOWLY DISSIPATE FROM NORTHWEST TO SOUTHEAST DURING THIS TIME. THE EASTERNMOST TERMINALS (KLAN AND KJXN) HAVE THE BEST CHANCE OF HOLDING ON TO CEILINGS FOR MOST OF THE DAY. ALTHOUGH NOT ADVERTISED SPECIFICALLY IN THE TAFS...A LOSS OF CEILINGS OVERNIGHT COMBINED WITH LIGHT WINDS WILL MAKE PATCHY FOG POSSIBLE. IF FOG WERE TO OCCUR AT THE TERMINALS...IT WOULD MOST LIKELY START AFTER 06Z AND HAVE A GOOD CHANCE OF DROPPING BELOW IFR VISIBILITY THRESHOLDS OF 3 MILES. THIS WILL BE THE MAIN THING TO WATCH THROUGH THE NEXT SCHEDULED TAF UPDATE. && .MARINE... ISSUED AT 328 AM EST THU MAR 7 2013 RATHER LIGHT NW WINDS TODAY WILL KEEP WAVES ON THE LOWER SIDE. WINDS REMAIN LIGHT THROUGH MUCH OF THE SHORT TERM. HOWEVER WINDS AND WAVES SHOULD INCREASE BY SATURDAY AFTERNOON AS THE NEXT SYSTEM APPROACHES. && .HYDROLOGY... ISSUED AT 328 AM EST THU MAR 7 2013 A GRADUAL THAW WILL CONTINUE WITH ABOVE FREEZING DAYTIME TEMPS AND DROPPING BELOW FREEZING AT NIGHT. WARMER CONDITIONS ARRIVE OVER THE WEEKEND ALONG WITH SOME RAIN. THIS COMBINATION WILL BE MONITORED FOR POSSIBLE HYDRO IMPACTS. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ UPDATE...JAM WDM SYNOPSIS...JK SHORT TERM...JK LONG TERM...MEADE AVIATION...TJT HYDROLOGY...JK MARINE...JK
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1048 AM EST THU MAR 7 2013 .SYNOPSIS... ISSUED AT 328 AM EST THU MAR 7 2013 LAKE SHORE AREAS WILL SEE OCCASIONAL FLURRIES OR LIGHT SNOW TODAY...OTHERWISE IT WILL BE PARTLY TO MOSTLY CLOUDY WITH TEMPERATURES IN THE 30S. DRY WEATHER IS EXPECTED FOR FRIDAY AND MUCH OF SATURDAY. TEMPERATURES WILL WARM TO AROUND 40 ON FRIDAY AND INTO THE 40S FOR SATURDAY. A RATHER UNSETTLED PERIOD IS EXPECTED LATE IN THE WEEKEND AND INTO EARLY NEXT WEEK. RAIN IS EXPECTED BY LATE SATURDAY OR SATURDAY NIGHT AND CONTINUING INTO SUNDAY. THE PRECIPITATION MAY CHANGE TO SNOW...OR A MIX OF RAIN AND SNOW SUNDAY NIGHT THROUGH MONDAY NIGHT...AS TEMPERATURES COOL FOR NEXT WEEK. && .UPDATE... ISSUED AT 1046 AM EST THU MAR 7 2013 I DECREASED CLOUD COVER FOR THE REMAINDER OF THE DAY. MANY OF THE CLOUDS THAT WERE AROUND THIS MORNING HAVE CONTINUED TO ERODE AND EXIT TO EAST. CLEARING WILL CONTINUE FROM WEST TO EAST THIS AFTERNOON AND THIS IS SHOWN BY THE NAM AND RAP MODEL SUGGESTIONS. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 328 AM EST THU MAR 7 2013 A SMALL AREA OF LAKE EFFECT SNOW SHOWERS/FLURRIES WAS CLIPPING WESTERN VAN BUREN COUNTY THIS MORNING. EXPECT THIS MAY LINGER MUCH OF TODAY AS COLD ADVECTION PEAKS AROUND MID DAY. THE FLOW REMAINS 330-350 SO ONLY THE LAKE SHORE WILL EXPERIENCE OCCASIONAL FLURRIES OR LIGHT SNOW. IT COULD RESULT IN A LIGHT DUSTING IN SOME LOCALES. INLAND AREAS SHOULD SEE A MIX OF CLOUDS AND SUN...WITH THE CLOUDS MORE FREQUENT THAN SUN. SLIGHTLY COOLER THAN YESTERDAY WITH MOSTLY LOW AND MID 30S FOR HIGHS. UPPER RIDGING MOVES FOR THE END OF THE WORK WEEK. ALONG WITH THIS WILL COME WARM ADVECTION. ANY LAKE SNOW SHOULD END BY THIS EVENING ON THE HEELS OF THE WARM ADVECTION. SKIES SHOULD GRADUALLY CLEAR LEADING TO A MOSTLY SUNNY FRIDAY WITH TEMPS APPROACHING 40. CLOUDS SHOULD THICKEN THROUGH SATURDAY WITH WARM ADVECTION CLOUDS AND AN INCREASING GULF MOISTURE FLOW. THE WARM FETCH WILL PUSH TEMPS WELL INTO THE 40S. WE MAY SEE A FEW RAIN SHOWERS TOWARD SATURDAY EVENING AS THE LOW LEVELS MOISTEN AHEAD OF A SYSTEM DEVELOPING OVER THE CENTRAL PLAINS. .LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 328 AM EST THU MAR 7 2013 SCATTERED TO NUMEROUS RAIN SHOWERS ARE EXPECTED SATURDAY NIGHT AND SUNDAY AS A WARM AIR ADVECTION PATTERN IMPACTS THE REGION. 40 TO 50 KT SOUTHERLY LOW LEVEL JET IS PROGGED OUT AHEAD OF AN APPROACHING FRONTAL BOUNDARY... WITH NARROW CORRIDOR OF PWATS AROUND ONE INCH STREAMING NORTH. WILL NOT INCLUDE THUNDER AT THIS POINT... BUT WILL HAVE TO WATCH FOR THAT POSSIBILITY. MODELS ARE STILL STRUGGLING WITH TIMING/STRENGTH OF JET STREAK ENERGY EJECTING NORTHEAST FROM THE FOUR CORNERS REGION... BUT IT DOES LIKE A STRONG SHORTWAVE WILL BE MOVING INTO IOWA AROUND 12Z SUNDAY. CURRENT MODEL SOLUTIONS IMPLY THAT THE SHORTWAVE MOVING NEWD FROM THE CENTRAL PLAINS REGION ON SUNDAY WILL WEAKEN AND SHEAR OUT AS IT COMES INTO MI AND GETS ABSORBED IN WITH AN APPROACHING NRN STREAM TROUGH. THE SFC FRONTAL BOUNDARY ALSO WEAKENS BUT DOES SLIP THROUGH THE ENTIRE CWFA BY 12Z MONDAY. MODELS HAVE BEEN VERY INCONSISTENT IN REGARDS TO WHAT HAPPENS AFTER THAT... BUT CONTINUE TO SUGGEST THE POSSIBILITY OF ANOTHER WAVE MOVING MOVING NORTHEAST ALONG THE SFC FRONT EARLY NEXT WEEK. PRECIP TYPE REMAINS PROBLEMATIC... SINCE IF THE FRONT GETS HUNG UP THEN THE LOW LEVEL COLD AIR MAY HAVE A TOUGH TIME FILTERING INTO THE REGION FROM THE NORTH. DESPITE THE MODEL INCONSISTENCIES FOR EARLY NEXT WEEK... ALL SOLUTIONS SEEM TO EVENTUALLY CONVERGE ON A RATHER CHILLY PATTERN BY MID WEEK WITH TROUGHING AND COLD AIR ALOFT. THIS WOULD LEAD TO SCATTERED SNOW OR MIXED RAIN AND SNOW SHOWERS AND HIGHS IN THE 30S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 655 AM EST THU MAR 7 2013 MVFR CIGS WERE IMPACTING MUCH OF THE AREA THIS MORNING... BUT CONDITIONS SHOULD TREND TOWARD MOSTLY VFR BY NOON AS HIGH PRESSURE OVER WISCONSIN MOVES EAST. THERE HAS BEEN AREAS OF IFR/LIFR FOG ASSOCIATED WITH THE SFC HIGH PRESSURE RIDGE CURRENTLY TO OUR WEST. THAT MAY BE A CONCERN ACROSS MICHIGAN LATE TONIGHT SINCE THE RIDGE WILL BE OVERHEAD. HOWEVER AT THIS POINT OPTED TO LEAVE IT OUT OF THE TAFS AS CONFIDENCE IN FOG DEVELOPMENT IS LOW AND IT IS DEPENDENT ON CLEARING OF THE CURRENT CLOUD COVER. && .MARINE... ISSUED AT 328 AM EST THU MAR 7 2013 RATHER LIGHT NW WINDS TODAY WILL KEEP WAVES ON THE LOWER SIDE. WINDS REMAIN LIGHT THROUGH MUCH OF THE SHORT TERM. HOWEVER WINDS AND WAVES SHOULD INCREASE BY SATURDAY AFTERNOON AS THE NEXT SYSTEM APPROACHES. && .HYDROLOGY... ISSUED AT 328 AM EST THU MAR 7 2013 A GRADUAL THAW WILL CONTINUE WITH ABOVE FREEZING DAYTIME TEMPS AND DROPPING BELOW FREEZING AT NIGHT. WARMER CONDITIONS ARRIVE OVER THE WEEKEND ALONG WITH SOME RAIN. THIS COMBINATION WILL BE MONITORED FOR POSSIBLE HYDRO IMPACTS. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ UPDATE...JAM WDM SYNOPSIS...JK SHORT TERM...JK LONG TERM...MEADE AVIATION...MEADE HYDROLOGY...JK MARINE...JK
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1126 PM CST WED MAR 6 2013 .SHORT TERM...(TONIGHT THROUGH THURSDAY) ISSUED AT 353 PM CST WED MAR 6 2013 BIGGEST CHALLENGE WILL BE DETERMINING SKY COVER AND VISIBILITY FOR TONIGHT INTO EARLY THURSDAY MORNING. THE STRATUS THAT STUCK AROUND AND RETROGRADED WESTWARD INTO THE EASTERN HALF OF THE CWA HAS LONG MIXED OUT...WITH ONLY SOME CIRRUS MAKING ITS WAY INTO OUR CWA FROM THE SOUTH/SOUTHWEST. SATELLITE AND WATER VAPOR REVEAL SPLIT FLOW IN UPPER LEVELS...PLACING OUR CWA BETWEEN. THE SURFACE RIDGE CONTINUES TO TREK EAST...WHICH WILL EVENTUALLY TURN WIND TO A MORE SE TO S/SE WIND DIRECTION. MODELS ARE STILL KEYING IN ON SOME POSSIBLE STRATUS/FOG IN THE WESTERN CWA OVERNIGHT AND INTO THURSDAY MORNING...AND WITH THIS CONSISTENT SIGNAL...HAVE LEFT IN THE FOG FROM THE PREVIOUS FORECAST AND EXPANDED THIS A LITTLE FARTHER TO THE WEST. THE RAP IS PICKING UP SOME INCREASED STRATUS IN THE WEST AND EVENTUALLY NORTH AS A LOW-LEVEL JET INCREASED DURING THE OVERNIGHT. THE NMM ALSO INDICATES SOME INCREASE STRATUS OVERNIGHT...BUT OVER A LARGER PORTION OF THE CWA. CONFIDENCE REMAINS LOW FOR SKY COVER TONIGHT AS MODELS DO NOT HAVE A GREAT HANDLE ON LOW-LEVEL SKY COVER AND FRANKLY...HAVE NOT DONE THAT GREAT FOR AWHILE. THE NAM ADVERTISES SOME LIGHT QPF IN THE NORTHERN CWA...SOMEWHAT NEAR THE NOSE OF THE MODEST LOW-LEVEL JET DEVELOPING TONIGHT. WITH SUCH A DRY PROFILE...I DOUBT IF THERE IS MUCH CHANCE AT ALL OF MEASURABLE PRECIPITATION...ALTHOUGH THIS COULD BE AN INDICATOR OF SOME DEVELOPING STRATUS...WHICH SEEMS TO BE SUPPORTED BY THE USING RECENT VERIFICATION STATISTICS...I MADE SOME MINOR CHANGES TO TEMPERATURES FOR TONIGHT AND THURSDAY...WITH THE REMAINING SNOWPACK IN THE WESTERN CWA STILL HAVING SOME INFLUENCE WITH HIGH TEMPERATURES THURSDAY. THIS SNOWPACK MAY HAVE LIMITED EFFECT ON THE VISIBILITY FOR OVERNIGHT TONIGHT INTO THURSDAY MORNING AS WELL. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 353 PM CST WED MAR 6 2013 MAIN FORECAST CONCERNS ARE PRECIPITATION FRIDAY NIGHT THROUGH SUNDAY NIGHT AND TEMPERATURES THROUGH THE PERIOD. AN UPPER LEVEL RIDGE WILL MOVE THROUGH THE AREA THURSDAY NIGHT INTO FRIDAY. THERE IS WARM ADVECTION ACROSS THE AREA AND TEMPERATURES SHOULD BE WARMER. IN ADDITION...THE SOUTH WINDS INCREASE THE MOISTURE ACROSS THE AREA AND CLOUDS WILL INCREASE. A COUPLE OF THE MODELS HAVE STARTED SHOWING SOME LIGHT QPF ASSOCIATED WITH THE WARM ADVECTION. HAVE KEPT THE FORECAST DRY FOR NOW AND WILL WAIT FOR FURTHER RUNS. BY FRIDAY NIGHT AN UPPER LEVEL LOW PRESSURE SYSTEM MOVING OUT OF THE ROCKIES WILL START TO AFFECT THE AREA. PRECIPITATION SPREADS ACROSS THE AREA. WARM TEMPERATURES WILL KEEP PRECIPITATION IN THE FORM OF RAIN. THERE IS SOME WEAK INSTABILITY WITH MUCAPE UP TO 500 J/KG ACROSS THE AREA. THERE COULD BE SOME ISOLATED THUNDERSTORMS FRIDAY NIGHT INTO SATURDAY. SATURDAY WILL CONTINUE TO BE WARM AHEAD OF THE SURFACE LOW WITH SOUTHERLY WINDS. THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE TRACK OF THE UPPER LOW AS IT MOVES THROUGH THE PLAINS. AS THE UPPER LOW MOVES THROUGH THE PLAINS THE COLDER AIR MOVES INTO THE AREA FROM THE WEST. SATURDAY NIGHT THE PRECIPITATION CHANGES FROM RAIN TO SNOW IN THE WEST DURING THE EVENING THEN THE SNOW SPREADS ACROSS THE AREA DURING NIGHT. BY MORNING EXPECT SNOW IN THE NORTHWEST WITH RAIN AND SNOW FURTHER SOUTHEAST. ON SUNDAY SNOW WILL BE FOUND ACROSS MUCH OF THE AREA WITH SOME RAIN OR SNOW POSSIBLE IN THE SOUTHEAST. THE UPPER LOW WILL SLIDE TO THE EAST SUNDAY NIGHT AND PRECIPITATION WILL COME TO AN END. PRECIPITATION AMOUNTS ARE NOT VERY HIGH AND EXPECT SOME SNOW ACCUMULATIONS. SUNDAY WILL BE COLDER WITH HIGHS ONLY IN THE 30S BEHIND THE COLD FRONT. THE UPPER LOW WILL BE TO THE EAST AND THERE WILL BE NORTHWEST FLOW ACROSS THE AREA MONDAY THROUGH WEDNESDAY. THERE COULD BE SOME CLOUDS AS A FEW WEAK UPPER LEVEL WAVES MOVE THROUGH THE AREA...BUT THERE IS WARM ADVECTION AND TEMPERATURES SHOULD START TO WARM UP. DEPENDING ON HOW MUCH SNOW THERE IS SATURDAY NIGHT INTO SUNDAY THE TEMPERATURES MAY REMAIN A LITTLE COOLER FOR MONDAY...BUT WARM FOR TUESDAY AND WEDNESDAY. && .AVIATION...(FOR THE 06Z TAF THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1126 PM CST WED MAR 6 2013 VFR CONDITIONS ARE CURRENTLY FORECAST FOR THE TAF TONIGHT. MODELS ARE VERY INCONSISTENT WITH THE POSSIBILITY OF LOW STRATUS CEILINGS AND LLWS OVERNIGHT. HAVE HIGHER CONFIDENCE WITH LLWS SETTING UP THAN THE POSSIBILITY OF STRATUS...WILL CONTINUE TO MONITOR FOR STATUS SETTING UP LATER TONIGHT. VISIBILITIES SHOULD REMAIN VFR OVERNIGHT AS THE SURFACE WINDS WILL BE AROUND 10KTS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...HEINLEIN LONG TERM...JCB AVIATION...BEDA/BRYANT
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
634 PM EST FRI MAR 8 2013 .SYNOPSIS... SURFACE HIGH PRESSURE ACROSS THE CENTRAL GREAT LAKES WILL SHIFT INTO THE NORTHEAST OVER THE WEEKEND. THIS WILL RESULT IN MOSTLY CLEAR SKIES AND MUCH ABOVE NORMAL TEMPERATURES...ESPECIALLY HIGHS ON SUNDAY. THE NEXT CHANCE FOR PRECIPITATION MAINLY IN THE FORM OF RAIN SHOWERS WILL BE LATE MONDAY INTO TUESDAY. A SLOW COOLING TREND WILL DEVELOP TOWARD THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 623 PM EST FRIDAY...MINOR ADJUSTMENTS AS OF EARLY EVENING MAINLY TO TWEAK SKY COVER SLIGHTLY...AND BLEND CURRENT T/TD OBSERVATIONAL DATA AHEAD TO THE MIDNIGHT HOUR OR SO. CURRENT READINGS ARE RUNNING SOMEWHAT ABOVE PRIOR INDICATIONS...MAINLY DUE TO CONTINUED WIND/MIXED PBL AND IF LATEST RAP 2M TEMP DATA IS ANY INDICATION...WE MAY END UP A TAD MILDER OVERNIGHT. NO WHOLESALE CHANGES IN THAT REGARD AT THIS POINT AS I WANT TO SEE HOW THINGS TREND OVER THE NEXT FEW HOURS. REST OF FCST REMAINS LARGELY UNCHANGED. HAVE A GREAT EVENING. PRIOR DISCUSSION FOLLOWS... TONIGHT...MID/UPPER LVL RIDGE AND ASSOCIATED SFC HIGH PRES WL SLOWLY MOVE FROM THE CENTRAL GREAT LAKES INTO THE NE CONUS. THIS WL RESULT IN CLRING SKIES AND LIGHTER WINDS. RAP/GFS AND NAM SOUNDINGS SHOW PLENTY OF LLVL RH SFC SFC THRU 875MB TONIGHT...ESPECIALLY AT SLK...BUT BL WINDS REMAIN BTWN 6-10 KNTS. GIVEN GOOD RADIATIONAL COOLING...EXPECT SFC TEMPS TO REACH SFC DWPT TEMPS IN DEEPER/SHELTERED VALLEYS...WITH AREAS OF LOW CLOUDS/FG POSSIBLE...ESPECIALLY NORTHERN NY NEAR SLK. IN ADDITION...SOUNDINGS SHOW A SHARP INVERSION DEVELOPING WITH VALLEYS IN THE SINGLE DIGITS/LWR TEENS. MEANWHILE...MTN TOPS/MID SLOPES HOLD IN THE 20S TO NEAR 30F. AS SOUNDINGS SHOW A THERMAL BELT BTWN 2KFT AND 3KFT FEET OF TEMPS ABOVE 0C. CPV/SLV TEMPS WL RANGE IN THE UPPER TEENS TO LOWER 20S...WITH MAINLY SINGLE DIGITS/TEENS FOR THE NEK. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... AS OF 310 PM EST FRIDAY...BY SATURDAY...MID/UPPER LVL RIDGE MOVES OVERHEAD AND SOUNDINGS SHOW A DEEP DRY LAYER. THIS WL RESULT IN PLENTY OF SUNSHINE AND LIGHT WINDS. STILL SOME UNCERTAINTY WITH REGARDS TO AMOUNT OF MIXING...ESPECIALLY OVER THE SNOWPACK ACRS THE MTN VALLEYS OF THE DACK AND CENTRAL/EASTERN VT. PROGGED 85H TEMPS WARM TO 0C BY 18Z SAT...BUT SOUNDINGS SHOW MIXING ONLY TO 975MB...WHERE TEMPS ARE BTWN -1C AND -3C...ESPECIALLY CPV AND DEEPER VALLEYS. THESE THERMAL PROFILES AND SNOWPACK SUGGEST L/M40S CPV AND PARTS OF THE SLV/DACKS WITH M/U 30S OVER THE SNOWPACK VALLEYS OF CENTRAL/EASTERN VT...INCLUDING THE NEK. WOULD NOT BE SURPRISED IF MID SLOPE LOCATIONS BTWN 1200 AND 2500 FEET WARM INTO THE MID/UPPER 40S SATURDAY...GIVEN THE SHARP VERTICAL THERMAL GRADIENT. ANY LOW CLOUDS/BR SHOULD BURN OFF BY 14Z SATURDAY. MID/UPPER LVL RIDGE THEN SHIFTS INTO EASTERN NEW ENGLAND BY 12Z SUNDAY AS A WARM SOUTHERLY FLW CONTS ACRS OUR CWA. TEMPS WL BE TRICKY SAT NIGHT/SUNDAY MORNING WITH WARM READINGS IN THE 20S/30S IN THE MTNS AND COLDEST VALUES IN THE TEENS/LWR 20S IN DEEPER SNOWPACK VALLEYS. THERMAL PROFILES CONT TO SHOW A SHARP INVERSION ACRS OUR CWA. ON SUNDAY...HAVE NOTICED SE SFC TO 925MB FLW DEVELOPING ACRS OUR CENTRAL/EASTERN VT ZNS...WHICH MAY HELP TO ADVECT A LLVL COOL MARITIME AIRMASS INTO OUR FA. THIS WOULD LIMIT AMOUNT OF WARMING AND COULD KEEP TEMPS IN CENTRAL/EASTERN VT IN THE U30S TO M40S. MEANWHILE...NAM12 SHOWS 925MB TEMPS ACRS THE SE DOWNSLOPE REGIONS OF THE DACKS FROM GOUVERNEUR TO CANTON TO POTSDAM BTWN 8 AND 10C BY 00Z MONDAY...SUPPORTING HIGHS WELL INTO THE 50S TO NEAR 60F. PROGGED 925MB TEMPS ACRS EASTERN/CENTRAL VT...EAST OF THE GREENS ARE ONLY BTWN 2 AND 4C...WITH LIMITED MIXING...SUPPORTING MUCH COOLER TEMPS. MID/UPPER LVL MOISTURE INCREASES AFT 18Z SUNDAY ACRS OUR WESTERN CWA...AS NEXT S/W TROF APPROACHES. ON SUNDAY NIGHT...WARM SOUTHERLY FLW WL CONT ACRS OUR CENTRAL/WESTERN CWA...WITH TEMPS MUCH ABOVE NORMAL ANTICIPATED. EXPECT LOWS ONLY IN THE U30S TO M40S SUNDAY NIGHT ACRS THE SLV/CPV...WITH READINGS IN THE 20S ACRS EASTERN VT. BEST DEEP LAYER MOISTURE AND LIFT WL HOLD OFF UNTIL AFT 12Z MONDAY...THEREFORE WL CONT TO KEEP A MAINLY DRY FCST THRU THE PERIOD. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 315 PM EST FRIDAY...UPPER RIDGE MOVES EAST OF THE AREA EARLY MONDAY AND PRONOUNCED SOUTHWEST FLOW ALOFT DEVELOPS. WARM AIR ADVECTION WILL ALLOW TEMPERATURES TO CLIMB WELL INTO THE 40S AHEAD OF A COLD FRONT...THAT WILL NOT REALLY MOVE INTO THE AREA UNTIL LATER MONDAY NIGHT. WITH THE HIGHER AMPLITUDE FLOW...PRECIPITATION WILL BE CLOSELY TIED TO THE UPPER TROUGH AXIS/COLD FRONT. THUS MOST OF THE AREA WILL STAY DRY WITH SHOWERS MOVING IN LATE IN THE DAY ON MONDAY...ESPECIALLY OVER NORTHERN NEW YORK. GIVEN WARM TEMPERATURES...ANY PRECIPITATION WILL FALL IN THE FORM OF RAIN. COLD FRONT MOVES ACROSS THE AREA LATE MONDAY NIGHT INTO TUESDAY MORNING AND THIS WILL BE WHEN SHOWERS ARE LIKELY ACROSS THE ENTIRE AREA. GOING FORECAST HAS THIS COVERED WELL AND ONLY TWEAK WAS TO KEEP PRECIPITATION LASTING A BIT LONGER TUESDAY MORNING. THERE IS SOME COLDER AIR MOVING IN ON THE BACKSIDE OF THE UPPER TROUGH...THUS WE COULD SEE A COUPLE OF INCHES OVER THE HIGHER TERRAIN VERY LATE MONDAY NIGHT AND ESPECIALLY TUESDAY MORNING. OTHERWISE...MAIN PRECIPITATION SHIELD MOVES EAST OF THE AREA TUESDAY AFTERNOON AS UPPER TROUGH AXIS APPROACHES LATE TUESDAY NIGHT AND ESPECIALLY ON WEDNESDAY. COULD SEE SOME STEEPER LAPSE RATES KICKING OFF SOME RAIN/SNOW SHOWERS ON WEDNESDAY BEFORE TROUGH AXIS MOVES EAST AND WE WIND UP IN NORTHWEST FLOW ALOFT. DESPITE THE NORTHWEST FLOW ALOFT...TEMPERATURES WILL GENERALLY BE RIGHT AROUND SEASONAL NORMALS DURING THE DAY THURSDAY AND FRIDAY WITH ABOVE NORMAL TEMPERATURES AT NIGHT. HIGH PRESSURE BUILDING IN ON THE NORTHWEST FLOW ALOFT THURSDAY AND FRIDAY SUGGESTS DRY WEATHER WILL BE THE RULE. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... THROUGH 00Z SUNDAY...PREDOMINANTLY VFR EXPECTED THROUGH THE PERIOD. MAINLY CLEAR SKIES WITH ONLY FEW-SCT VFR HIGH CLOUDS FOR TONIGHT. GUSTY WINDS THIS EVENING WILL QUICKLY DIMINISH AFTER 00Z TO 5 KNOTS OT LESS. THE COMBINATION OF CLEAR SKIES AND LIGHT WINDS MAY ALLOW FOR SOME DEVELOPMENT OF FOG/BR AT MSS/SLK AFTER 08Z TONIGHT. HOWEVER WIDESPREAD COVERAGE IS NOT ANTICIPATED SO ONLY WENT TEMPO 3-4SM BR AT THIS TIME. LOW LEVEL DRYING SHOULD PROHIBIT FOG DEVELOPMENT AT ANY OTHER SITES. ANY FOG/BR WILL CLEAR AFTER 13Z SATURDAY MORNING WITH CLEAR SKIES EXPECTED FOR THE REMAINDER OF THE DAY WITH LIGHT NORTH WINDS. OUTLOOK 00Z SUNDAY THROUGH WEDNESDAY... 00Z SUNDAY THROUGH 12Z MONDAY...VFR UNDER HIGH PRESSURE. 12Z MONDAY THROUGH 00Z WEDNESDAY...PERIODS OF MVFR/IFR POSSIBLE IN RAIN SHOWERS AS COLD FRONT CROSSES THE REGION. 00Z WEDNESDAY ONWARD...PREDOMINANTLY VFR AS SYSTEM DEPARTS. A FEW MOUNTAIN SNOW SHOWERS POSSIBLE AT SLK/MPV. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...TABER NEAR TERM...JMG/TABER SHORT TERM...TABER LONG TERM...EVENSON AVIATION...MUCCILLI
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
623 PM EST FRI MAR 8 2013 .SYNOPSIS... SURFACE HIGH PRESSURE ACROSS THE CENTRAL GREAT LAKES WILL SHIFT INTO THE NORTHEAST OVER THE WEEKEND. THIS WILL RESULT IN MOSTLY CLEAR SKIES AND MUCH ABOVE NORMAL TEMPERATURES...ESPECIALLY HIGHS ON SUNDAY. THE NEXT CHANCE FOR PRECIPITATION MAINLY IN THE FORM OF RAIN SHOWERS WILL BE LATE MONDAY INTO TUESDAY. A SLOW COOLING TREND WILL DEVELOP TOWARD THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 623 PM EST FRIDAY...MINOR ADJUSTMENTS AS OF EARLY EVENING MAINLY TO TWEAK SKY COVER SLIGHTLY...AND BLEND CURRENT T/TD OBSERVATIONAL DATA AHEAD TO THE MIDNIGHT HOUR OR SO. CURRENT READINGS ARE RUNNING SOMEWHAT ABOVE PRIOR INDICATIONS...MAINLY DUE TO CONTINUED WIND/MIXED PBL AND IF LATEST RAP 2M TEMP DATA IS ANY INDICATION...WE MAY END UP A TAD MILDER OVERNIGHT. NO WHOLESALE CHANGES IN THAT REGARD AT THIS POINT AS I WANT TO SEE HOW THINGS TREND OVER THE NEXT FEW HOURS. REST OF FCST REMAINS LARGELY UNCHANGED. HAVE A GREAT EVENING. PRIOR DISCUSSION FOLLOWS... TONIGHT...MID/UPPER LVL RIDGE AND ASSOCIATED SFC HIGH PRES WL SLOWLY MOVE FROM THE CENTRAL GREAT LAKES INTO THE NE CONUS. THIS WL RESULT IN CLRING SKIES AND LIGHTER WINDS. RAP/GFS AND NAM SOUNDINGS SHOW PLENTY OF LLVL RH SFC SFC THRU 875MB TONIGHT...ESPECIALLY AT SLK...BUT BL WINDS REMAIN BTWN 6-10 KNTS. GIVEN GOOD RADIATIONAL COOLING...EXPECT SFC TEMPS TO REACH SFC DWPT TEMPS IN DEEPER/SHELTERED VALLEYS...WITH AREAS OF LOW CLOUDS/FG POSSIBLE...ESPECIALLY NORTHERN NY NEAR SLK. IN ADDITION...SOUNDINGS SHOW A SHARP INVERSION DEVELOPING WITH VALLEYS IN THE SINGLE DIGITS/LWR TEENS. MEANWHILE...MTN TOPS/MID SLOPES HOLD IN THE 20S TO NEAR 30F. AS SOUNDINGS SHOW A THERMAL BELT BTWN 2KFT AND 3KFT FEET OF TEMPS ABOVE 0C. CPV/SLV TEMPS WL RANGE IN THE UPPER TEENS TO LOWER 20S...WITH MAINLY SINGLE DIGITS/TEENS FOR THE NEK. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... AS OF 310 PM EST FRIDAY...BY SATURDAY...MID/UPPER LVL RIDGE MOVES OVERHEAD AND SOUNDINGS SHOW A DEEP DRY LAYER. THIS WL RESULT IN PLENTY OF SUNSHINE AND LIGHT WINDS. STILL SOME UNCERTAINTY WITH REGARDS TO AMOUNT OF MIXING...ESPECIALLY OVER THE SNOWPACK ACRS THE MTN VALLEYS OF THE DACK AND CENTRAL/EASTERN VT. PROGGED 85H TEMPS WARM TO 0C BY 18Z SAT...BUT SOUNDINGS SHOW MIXING ONLY TO 975MB...WHERE TEMPS ARE BTWN -1C AND -3C...ESPECIALLY CPV AND DEEPER VALLEYS. THESE THERMAL PROFILES AND SNOWPACK SUGGEST L/M40S CPV AND PARTS OF THE SLV/DACKS WITH M/U 30S OVER THE SNOWPACK VALLEYS OF CENTRAL/EASTERN VT...INCLUDING THE NEK. WOULD NOT BE SURPRISED IF MID SLOPE LOCATIONS BTWN 1200 AND 2500 FEET WARM INTO THE MID/UPPER 40S SATURDAY...GIVEN THE SHARP VERTICAL THERMAL GRADIENT. ANY LOW CLOUDS/BR SHOULD BURN OFF BY 14Z SATURDAY. MID/UPPER LVL RIDGE THEN SHIFTS INTO EASTERN NEW ENGLAND BY 12Z SUNDAY AS A WARM SOUTHERLY FLW CONTS ACRS OUR CWA. TEMPS WL BE TRICKY SAT NIGHT/SUNDAY MORNING WITH WARM READINGS IN THE 20S/30S IN THE MTNS AND COLDEST VALUES IN THE TEENS/LWR 20S IN DEEPER SNOWPACK VALLEYS. THERMAL PROFILES CONT TO SHOW A SHARP INVERSION ACRS OUR CWA. ON SUNDAY...HAVE NOTICED SE SFC TO 925MB FLW DEVELOPING ACRS OUR CENTRAL/EASTERN VT ZNS...WHICH MAY HELP TO ADVECT A LLVL COOL MARITIME AIRMASS INTO OUR FA. THIS WOULD LIMIT AMOUNT OF WARMING AND COULD KEEP TEMPS IN CENTRAL/EASTERN VT IN THE U30S TO M40S. MEANWHILE...NAM12 SHOWS 925MB TEMPS ACRS THE SE DOWNSLOPE REGIONS OF THE DACKS FROM GOUVERNEUR TO CANTON TO POTSDAM BTWN 8 AND 10C BY 00Z MONDAY...SUPPORTING HIGHS WELL INTO THE 50S TO NEAR 60F. PROGGED 925MB TEMPS ACRS EASTERN/CENTRAL VT...EAST OF THE GREENS ARE ONLY BTWN 2 AND 4C...WITH LIMITED MIXING...SUPPORTING MUCH COOLER TEMPS. MID/UPPER LVL MOISTURE INCREASES AFT 18Z SUNDAY ACRS OUR WESTERN CWA...AS NEXT S/W TROF APPROACHES. ON SUNDAY NIGHT...WARM SOUTHERLY FLW WL CONT ACRS OUR CENTRAL/WESTERN CWA...WITH TEMPS MUCH ABOVE NORMAL ANTICIPATED. EXPECT LOWS ONLY IN THE U30S TO M40S SUNDAY NIGHT ACRS THE SLV/CPV...WITH READINGS IN THE 20S ACRS EASTERN VT. BEST DEEP LAYER MOISTURE AND LIFT WL HOLD OFF UNTIL AFT 12Z MONDAY...THEREFORE WL CONT TO KEEP A MAINLY DRY FCST THRU THE PERIOD. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 315 PM EST FRIDAY...UPPER RIDGE MOVES EAST OF THE AREA EARLY MONDAY AND PRONOUNCED SOUTHWEST FLOW ALOFT DEVELOPS. WARM AIR ADVECTION WILL ALLOW TEMPERATURES TO CLIMB WELL INTO THE 40S AHEAD OF A COLD FRONT...THAT WILL NOT REALLY MOVE INTO THE AREA UNTIL LATER MONDAY NIGHT. WITH THE HIGHER AMPLITUDE FLOW...PRECIPITATION WILL BE CLOSELY TIED TO THE UPPER TROUGH AXIS/COLD FRONT. THUS MOST OF THE AREA WILL STAY DRY WITH SHOWERS MOVING IN LATE IN THE DAY ON MONDAY...ESPECIALLY OVER NORTHERN NEW YORK. GIVEN WARM TEMPERATURES...ANY PRECIPITATION WILL FALL IN THE FORM OF RAIN. COLD FRONT MOVES ACROSS THE AREA LATE MONDAY NIGHT INTO TUESDAY MORNING AND THIS WILL BE WHEN SHOWERS ARE LIKELY ACROSS THE ENTIRE AREA. GOING FORECAST HAS THIS COVERED WELL AND ONLY TWEAK WAS TO KEEP PRECIPITATION LASTING A BIT LONGER TUESDAY MORNING. THERE IS SOME COLDER AIR MOVING IN ON THE BACKSIDE OF THE UPPER TROUGH...THUS WE COULD SEE A COUPLE OF INCHES OVER THE HIGHER TERRAIN VERY LATE MONDAY NIGHT AND ESPECIALLY TUESDAY MORNING. OTHERWISE...MAIN PRECIPITATION SHIELD MOVES EAST OF THE AREA TUESDAY AFTERNOON AS UPPER TROUGH AXIS APPROACHES LATE TUESDAY NIGHT AND ESPECIALLY ON WEDNESDAY. COULD SEE SOME STEEPER LAPSE RATES KICKING OFF SOME RAIN/SNOW SHOWERS ON WEDNESDAY BEFORE TROUGH AXIS MOVES EAST AND WE WIND UP IN NORTHWEST FLOW ALOFT. DESPITE THE NORTHWEST FLOW ALOFT...TEMPERATURES WILL GENERALLY BE RIGHT AROUND SEASONAL NORMALS DURING THE DAY THURSDAY AND FRIDAY WITH ABOVE NORMAL TEMPERATURES AT NIGHT. HIGH PRESSURE BUILDING IN ON THE NORTHWEST FLOW ALOFT THURSDAY AND FRIDAY SUGGESTS DRY WEATHER WILL BE THE RULE. && .AVIATION /23Z FRIDAY THROUGH WEDNESDAY/... THROUGH 18Z SATURDAY...LARGE CLOUD SHIELD CONTINUES TO MOVE SOUTH THIS AFTERNOON AND MOST LOCATIONS ARE REPORTING VFR CEILINGS AND VISIBILITIES. THE ONLY EXCEPTION TO THIS IS AT KBTV AND KPBG WHERE MVFR CEILINGS EXIST EARLY THIS AFTERNOON...BUT SHOULD BECOME VFR BY 22Z. EXPECT VFR CONDITIONS FOR THE REMAINDER OF THE PERIOD WITH THE ONLY EXCEPTION BEING KSLK...WHERE MVFR CEILINGS AND VISIBILITIES WILL DEVELOP BETWEEN 06Z AND 13Z. WIND GUSTS FROM THE NORTH WILL CONTINUE IN THE 15 TO 25 KNOT RANGE THIS AFTERNOON...BUT DROP QUICKLY AROUND 00Z. LIGHT AND VARIABLE WINDS ARE THEN EXPECTED FOR THE REMAINDER OF THE PERIOD. OUTLOOK 18Z SATURDAY THROUGH TUESDAY... 18Z SATURDAY THROUGH 18Z SUNDAY...VFR UNDER HIGH PRESSURE. 18Z SUNDAY THROUGH TUESDAY...VFR TRENDING TO MVFR IN PERIODS OF RAIN/SNOW SHOWERS AS A COLD FRONT PUSHES THROUGH THE REGION. BRIEF IFR POSSIBLE IN HEAVIER SNOW. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...TABER NEAR TERM...JMG/TABER SHORT TERM...TABER LONG TERM...EVENSON AVIATION...EVENSON/LAHIFF
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
109 AM EST THU MAR 7 2013 .SYNOPSIS... A WINTER STORM WILL MOVE OFF THE MID ATLANTIC COAST AND SLOW DOWN AS IT MOVES UP THE NORTHEASTERN SEABOARD TONIGHT THROUGH THURSDAY NIGHT. AN UPPER LEVEL LOW WILL TRACK SOUTHEAST FROM THE UPPER GREAT LAKES TONIGHT THROUGH THURSDAY NIGHT AND SPREAD MORE SNOW TO MUCH OF CENTRAL NEW YORK AND NORTHEAST PENNSYLVANIA THURSDAY AFTERNOON AND NIGHT. THE SNOW COULD MIX WITH RAIN AT TIMES IN THE VALLEYS THURSDAY AFTERNOON. ALL THE PRECIPITATION WILL TAPER OFF FRIDAY. HIGH PRESSURE AND MILDER WEATHER WILL MOVE INTO THE REGION FOR THE WEEKEND. && .NEAR TERM /THROUGH TODAY/... RECENT RADAR TRENDS SHOWING ANY LINGERING SNOW ACTIVITY QUICKLY EXITING OFF THE EAST COAST THIS EVENING AS MAIN SFC LOW CONTINUES TO EXIT TOWARDS THE 40N/70W BENCHMARK. LATEST HRRR AND NEWLY ARRIVING 00Z NAM BOTH VALIDATE CURRENT RADAR TRENDS AND KEEP ANY QPF OVERNIGHT EAST OF THE CWA. AS A RESULT...HAVE TRIMMED BACK ON POPS ACCORDINGLY AND FEEL MUCH IF NOT THE WHOLE NIGHT SHOULD BE PRECIP FREE. ASIDE FROM THAT...HOURLY TEMPS ADJUSTED AS COLD AIR ADVECTION ON BACKSIDE OF DEPARTING LOW HAS YET TO ARRIVE. BY EARLY MORNING...LOWS SHOULD BOTTOM OUT TOWARDS THE UPPER 20S ACROSS MOST LOCATIONS. && .SHORT TERM /TONIGHT THROUGH SATURDAY/... 1025 PM UPDATE... NEWLY ARRIVING 00Z MODEL GUIDANCE FURTHER SUPPORTING CONCERNS FOR SNOWFALL BEGINNING LATE THURSDAY AFTERNOON AS WRAP AROUND MOISTURE ON THE BACKSIDE OF AFOREMENTIONED UPPER LOW GETS PULLED WESTWARD IN ADVANCE OF ANOTHER NORTHERN STREAM TROUGH/CLOSED LOW DIVING SOUTHEAST FROM THE NORTHERN LAKES. IN FACT...LATEST WATER VAPOR IMAGERY NOW SHOWING THE APPROACHING WAVE QUITE WELL AND THIS FEATURE WILL CONTINUE DIVING SOUTHEAST THROUGH CENTRAL PA THU NGT/EARLY FRI. 24-HR QPF TOTALS FROM THE NAM SUGGEST OVER 1" OF WATER EQUIVALENT FOR THE EASTERN ZONES...WITH UP TO .7" AS FAR WEST AS THE I-81 CORRIDOR. FOR WHAT ITS WORTH...18Z GFS ALSO SHOWING SOME WESTWARD DISPLACEMENT OF MAIN QPF AXIS WHICH LENDS SUPPORT TO AT LEAST HIGH-END ADVISORY SNOWFALLS FOR THE EASTERN ZONES. FOR NOW...WILL HOLD OFF ON MAKING ANY WHOLESALE CHANGES AND ALLOW THE OVERNIGHT SHIFT TO EVALUATE THE FULL MODEL SUITE BEFORE MAKING ANY HEADLINE ADJUSTMENTS. PREVIOUS SHORT TERM DISCUSSION... WATER VAPOR IMAGERY SHOWS A POTENT UPPER LEVEL LOW DIVING SOUTHEASTWARD FROM THE UPPER GREAT LAKES AT PRESENT. THIS FEATURE WILL CONT SE REACHING WRN NY THU EVE AND THEN DOWN TO THE DELMARVA PENINSULA BY 12Z FRI. MEANWHILE THE LARGE CYCLONE THAT WAS MOVG THRU THE MID- ATLANTIC STATES AT PRESENT WILL MOVE OFFSHORE BUT SLOW DOWN AND EXPAND ITS LOW TO MID LEVEL EASTERLY FLOW TO ENCOMPASS ALL OF C NY AND NE PA THU AFTERNOON AND NIGHT. MOISTURE ADVECTION IN THIS LOW TO MID LEVEL EASTERLY FLOW WILL RISE ISENTROPICALLY ESP ACRS ERN NY AND NE PA AS THE UPPER LEVEL LOW MOVING SE ALSO LIFTS THE ISENTROPES. THIS IS AN EXCELLENT DYNAMICAL SET-UP TO FORCE PRECIPITATION OVER MUCH OF C NY/NE PA LATE THU AFTERNOON AND NIGHT. SINCE MOST OF THE PRECIPITATION WILL FALL AT NIGHT AND ALSO FOCUS ON OUR HIGHER TERRAIN AREAS IN OTSEGO...DELAWARE AND SULLIVAN CO/S IT WILL BE MAINLY SNOW. HEAVIEST PRECIPITATION WILL BE IN OUR EASTERN ZONES WHERE THE LIFTG WILL BE THE HIGHEST AND THE MOISTURE WILL BE DEEPER. HENCE OPTED FOR A WINTER WX ADVY IN DELAWARE...OTSEGO AND SULLIVAN CO/S THU PM TO FRI AM GIVEN THE CONSENSUS OF THE 12Z GFS...12Z CMC...12Z HI RES NMM...AND THE 15Z SREF. BLENDED MODEL SNOWFALL FROM THESE SOURCES AND CAME UP WITH BASICALLY 3-4 INCHES IN THE DEEPEST VALLEYS OF DELAWARE...SULLIVAN AND OTSEGO CO/S TO 6-8 INCHES OVER THE HIGHEST TERRAIN. MOST OF THESE COUNTIES ARE FAIRLY ELEVATED SO MOST AREAS LIKELY WILL SEE 4-6 INCHES. REST OF C NY AND NE PA LIKELY WILL SEE LESS THAN 1 INCH IN VALLEYS TO AS MUCH AS 3 INCHES HIGHER TERRAIN ALONG THE I-81 CORRIDOR IN NY. WE DISCOUNTED THE NAM WHICH BURIES THE POCONOS AND CATSKILLS WITH 10-20 INCHES OF SNOW AND GIVES A LARGE PART OF THE REST OF OUR AREA 5-10 INCHES OF SNOW. BUT THIS TYPE OF SCENARIO DOES BEAR WATCHING AS THEIR IS STRG MID-LVL FGEN FRCG IN THE PRESENCE OF WEAK TO NEGATIVE EPV IN THESE AREAS. FOR NOW WAY TOO UNCERTAIN TO JUMP ON THIS BAND WAGON AND GIVEN THE TRACK RECORD OF THE NAM/S SNOWFALL RECENTLY WE DID NOT USE FOR NOW. THE SNOW PEAKS THURSDAY NIGHT AND TAPERS DOWN TO SNOW SHOWERS FLURRIES AND POTENTIALLY EVEN SOME SPRINKLES/RAIN SHOWERS IN THE LOWER ELEVATIONS FRIDAY. FRIDAY NIGHT AND SATURDAY LOOK FAIR WITH MILDER TEMPERATURES ON SATURDAY AS A RDG OF HIGH PRESSURE BUILDS IN. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... GIVEN TDA`S FOCUS ON SHORT TERM CONCERNS...WE USED HPC GUIDANCE FOR THE MED RNG. WE DID MAKE SOME MINOR TWEEKS...PRIMARILY TO CLD COVER (MORE PESSIMISTIC) AND TO A LESSER XTNT WINDS AND TEMPS AS A BACK DOOR CDFNT TRIES TO DROP SWD ON SUN NGT. THIS FEATURE COULD HAVE A SIG EFFECT ON TEMPS ACRS NRN ZONES ON MON...IN ADVANCE OF THE OCCLUDED FNT FCST TO PASS LATE ON MON NGT. AFTER SOME MILD TEMPS THIS WEEKEND...READINGS WILL COOL BY MID WEEK TO MORE SEASONABLE VALUES. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... A THICK VFR STRATUS DECK WILL HANG OVER THE TERMINALS INTO THE AFTERNOON HOURS ON THURSDAY. TEMPO MVFR CEILINGS ARE POSSIBLE AT KBGM MAINLY DUE TO ELEVATION EFFECTS. A STORM SYSTEM OFF THE ATLANTIC COAST WILL WRAP MOISTURE BACK ACROSS NY AND PA THURSDAY NIGHT. SNOW MAY REACH INTO THE I-81 CORRIDOR, BRINGING LOW MVFR AND TEMPO IFR RESTRICTIONS TO MOST OF THE TERMINALS. TIMING SUGGESTS THE SNOW WILL BEGIN BETWEEN 23Z AND 02Z, AND CONTINUE THROUGH LATE MORNING FRIDAY. THE BEST CHANCE FOR LONG TERM RESTRICTIONS WILL BE AT AVP AND BGM. .OUTLOOK... FRI/SAT/SUN...MVFR IN -SN INTO MIDDAY FRI. VFR OTHERWISE. MON...MVFR IN -SHRA. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...WINTER WEATHER ADVISORY FROM 1 PM THIS AFTERNOON TO 11 AM EST FRIDAY FOR NYZ046-057-062. && $$ SYNOPSIS...DJN NEAR TERM...CMG/DJN SHORT TERM...DJN LONG TERM... AVIATION...DJP
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1150 AM EST THU MAR 7 2013 .SYNOPSIS... STRONG LOW PRESSURE OFF THE MIDATLANTIC COAST WILL MOVE FURTHER OUT TO SEA TODAY. DRY HIGH PRESSURE WILL BUILD INTO THE REGION THIS AFTERNOON... AND LINGER THROUGH THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1022 AM THURSDAY... REST OF TODAY: A MUCH QUIETER DAY THAN THE LAST FEW... ALTHOUGH WE`LL STILL SEE SOME CLOUDINESS (ESPECIALLY FAR WEST AND IN THE NORTHEAST) ALONG WITH BELOW-NORMAL TEMPS AND GUSTY WINDS. THE POWERFUL STORM SYSTEM IS CENTERED WELL OFF THE MIDATLANTIC COAST ACCORDING TO THE LATEST SURFACE ANALYSIS... ALTHOUGH ITS CIRCULATION WILL CONTINUE TO PULL LOW LEVEL MOISTURE (BENEATH THE SUBSIDENCE INVERSION ALOFT) INTO NORTH CENTRAL AND NORTHEAST NC. 925-850 MB PROGS FROM THE 12KM NAM AS WELL AS THE HRRR INDICATE STRATOCU SPREADING TO THE SSE INTO THIS AREA TODAY... AND MORNING SOUNDINGS AND TRAJECTORIES ALONG WITH SATELLITE IMAGERY SUPPORT A PERIOD OF PARTLY SUNNY TO MOSTLY CLOUDY SKIES OVER THE COASTAL PLAIN AND NORTHEAST PIEDMONT THROUGH THE REST OF THE DAY. OVER THE FAR WESTERN PIEDMONT... OROGRAPHICALLY ENHANCED CIRRUS IS LIKELY TO PERSIST FOR A FEW MORE HOURS GIVEN THAT OBSERVED AND FORECAST SOUNDINGS SHOW A FAVORABLE WIND PROFILE. THE THICKER CLOUDS IN THE NORTHEAST WILL IMPACT TEMPS... AS SUGGESTED BY THE LATEST HRRR OUTPUT... SUGGESTING HIGHS THERE IN THE LOWER 50S... WHEREAS AREAS FROM THE TRIANGLE AND TRIAD TO THE SOUTH AND SW SHOULD SEE HIGHS IN THE MID-UPPER 50S. THE MIXED LAYER NOTED IN FORECAST SOUNDINGS SUPPORTS GUSTS AROUND 20-25 MPH IN THE FAR NORTHEAST (NEAREST THE TIGHTER MSLP GRADIENT) BUT JUST 15-20 ELSEWHERE... BEFORE THE DEPARTURE OF THE STORM SYSTEM RESULTS IN A SLOW DIMINISHING OF WINDS TOWARD NIGHTFALL. -GIH TONIGHT...STRONG VORT MAX IN THE NW FLOW ALOFT WILL DROP SEWD FROM THE NORTHERN GREAT LAKES INTO NORTHERN MID ATLANTIC TONIGHT THEN OFF THE VIRGINIA CAPE BY EARLY FRI. THIS SYSTEM WILL BE MOISTURE STARVED SO EXPECT LITTLE IN THE MANNER OF CLOUDS. HOWEVER...THIS SYSTEM WILL MAINTAIN A FAIRLY TIGHT PRESSURE GRADIENT SO WINDS WILL MAINTAIN 5-9KTS OVERNIGHT. THIS MIXING WILL AID TO KEEP TEMPS UP A BIT. IF SFC WINDS DECOUPLE...MORE LIKELY IN THE WESTERN PIEDMONT...COULD SEE TEMPS TUMBLE 4-5 DEGREES COLDER THAN FORECAST. MIN TEMPS UPPER 20S WEST TO LOWER 30S COASTAL PLAIN. -WSS && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 300 AM THURSDAY... FRIDAY AND FRIDAY NIGHT...AS STRONG VORT EXITS OFF THE MID ATLANTIC COAST...LOW LEVEL FLOW WILL BECOME MORE N-NE. SOME MODELS (ESPECIALLY NAM) DEPICT MORE OF A FETCH OFF THE ATLANTIC WHILE THE GFS AND ECMWF MAINTAIN A NLY FLOW (MAINLY OVER LAND). CONSIDERING THE AMOUNT OF MOISTURE ON THE BACK SIDE OF THE DEEP LOW...NAM MAY BE ONTO SOMETHING. THUS HAVE INCREASED CLOUD COVERAGE IN THE EAST LATE FRI INTO FRIDAY NIGHT. WITH A FEW MORE CLOUDS EXPECTED NE VERSUS SW...SHOULD SEE COOLER MAX TEMPS NE AND WARMER SW. MAX TEMPS NEAR 50 NORTHERN COASTAL PLAIN TO MID-UPPER 50S SW. MIN TEMPS FRIDAY NIGHT HIGHLY DEPENDENT ON EXTENT OF CLOUD COVERAGE. USED A BLEND OF MOS GUIDANCE FOR MIN TEMPS. HOWEVER IF CLOUDS DO MATERIALIZE...MIN TEMPS WILL NEED TO BE ADJUSTED UP A FEW DEGREES. CONVERSELY...IF CLOUDS DO NOT FORM AND SFC WINDS DECOUPLE...MIN TEMPS WILL NEED TO BE ADJUSTED DOWN 4-5 DEGREES. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 250 AM THURSDAY... THIS WEEKEND: BENEATH A BUILDING AND SLOWLY PROGRESSIVE RIDGE ALOFT...1030 MB SURFACE HIGH PRESSURE WILL SPAN THE LENGTH OF THE EAST COAST. THE RIDGING WILL PROVIDE FOR GENERALLY CLEAR AND MODERATING CONDITIONS FOR CENTRAL NC...WITH THE ONLY APPRECIABLE CLOUD COVER...ASIDE FROM CIRRUS...LIKELY TO HOLD WEST OF THE YADKIN IN RETURN LOW LEVEL FLOW SUN NIGHT-MON MORNING. STEADILY RISING THICKNESSES SUGGEST HIGHS AROUND 60 DEGREES SAT...AND IN THE LOWER-MIDDLE 60S SUN. BELOW GUIDANCE LOWS IN THE 29 TO 34 DEGREE RANGE WITH EXCELLENT RADIATIONAL SAT NIGHT...AND ABOUT 10 DEGREES MILDER SUN NIGHT. MONDAY THROUGH WEDNESDAY: THE DEEP LAYER RIDGING WILL CONTINUE EASTWARD IN THE AFOREMENTIONED SLOWLY PROGRESSIVE FLOW...IN ADVANCE OF A COMPLEX TROUGH ALOFT OVER AND OFFSHORE THE PAC NW COAST THIS MORNING. MEDIUM RANGE GUIDANCE IS IN REASONABLY GOOD AGREEMENT REGARDING THE PROGRESSION OF THIS TROUGH AND ACCOMPANYING WET LOW LEVEL FRONTAL ZONE ACROSS CENTRAL NC MON NIGHT-TUE...WITH A PRECEDING RESIDUAL CAPPING INVERSION LIKELY TO HOLD THROUGH THE DAY MON. INHERENT UNCERTAINTY AT THIS TIME RANGE FAVORS HOLDING POP IN THE 50-60 PERCENT RANGE...BUT CATEGORICAL PROBABILITIES WILL ULTIMATELY BE WARRANTED WITH TIME GIVEN THE EXPECTED WIDE-OPEN AND STRONG GULF INFLOW INTO THE FRONTAL ZONE. POST-FRONTAL COOLER AND DRIER CONDITIONS WILL PREVAIL FOR MID-LATE WEEK. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 1150 AM THURSDAY... HIGH CONFIDENCE IN CONTINUED VFR CONDITIONS THROUGH FRIDAY. THE LOW PRESSURE SYSTEM FROM THE LAST FEW DAYS WILL CONTINUE A STEADY EASTWARD DRIFT OUT TO SEA TODAY... HOWEVER THE CIRCULATION WILL STILL INFLUENCE US AS WE WILL MAINTAIN A MAINLY NORTHERLY BREEZE THIS AFTERNOON -- STRONGER (10-15 KTS GUSTING TO 20-25 KTS) AT RWI TAPERING WEAKER (AROUND 10 KTS WITH INFREQUENT GUSTS AROUND 15 KTS) AT INT/GSO. SURFACE HIGH PRESSURE CENTERED OVER ONTARIO AND THE UPPER GREAT LAKES WILL EXTEND WELL SOUTHWARD... BUILDING SLOWLY EASTWARD OVER EASTERN NOAM OVER THE NEXT 36 HOURS. ANY CLOUDS TODAY WILL BE BASED ABOVE 3 THOUSAND FT AGL... MOST EXTENSIVE AT RWI/RDU/FAY. SKIES WILL BECOME UNLIMITED THIS EVENING AND REMAIN SO WELL INTO FRIDAY WITH JUST LIGHT (10 KTS OR LOWER) WINDS FROM THE NORTH. LOOKING BEYOND FRIDAY AFTERNOON... MID-LEVEL LOW PRESSURE OVER LAKE SUPERIOR THIS MORNING WILL DROP SOUTHEASTWARD BRUSHING NORTHEAST NC LATE FRIDAY INTO FRIDAY NIGHT... AND THIS MAY BRING A PERIOD OF SCT-BKN CLOUDS AT 2500-3000 FT AGL LATE FRIDAY NIGHT AT RDU/RWI. OTHERWISE VFR CONDITIONS WILL HOLD INTO LATE SUNDAY MORNING THROUGH MONDAY MORNING... WHEN MOIST LOW LEVEL FLOW WILL BRING A RISK OF IFR CONDITIONS. BREEZY WINDS FROM THE SOUTHWEST AND MVFR CIGS/VSBYS WITH SHOWERS ARE POSSIBLE LATE MONDAY INTO TUESDAY AS FRONTAL SYSTEM CROSSES THE REGION. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD/WSS SHORT TERM...WSS LONG TERM...MWS AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1022 AM EST THU MAR 7 2013 .SYNOPSIS... STRONG LOW PRESSURE OFF THE MIDATLANTIC COAST WILL MOVE FURTHER OUT TO SEA TODAY. DRY HIGH PRESSURE WILL BUILD INTO THE REGION THIS AFTERNOON... AND LINGER THROUGH THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1022 AM THURSDAY... REST OF TODAY: A MUCH QUIETER DAY THAN THE LAST FEW... ALTHOUGH WE`LL STILL SEE SOME CLOUDINESS (ESPECIALLY FAR WEST AND IN THE NORTHEAST) ALONG WITH BELOW-NORMAL TEMPS AND GUSTY WINDS. THE POWERFUL STORM SYSTEM IS CENTERED WELL OFF THE MIDATLANTIC COAST ACCORDING TO THE LATEST SURFACE ANALYSIS... ALTHOUGH ITS CIRCULATION WILL CONTINUE TO PULL LOW LEVEL MOISTURE (BENEATH THE SUBSIDENCE INVERSION ALOFT) INTO NORTH CENTRAL AND NORTHEAST NC. 925-850 MB PROGS FROM THE 12KM NAM AS WELL AS THE HRRR INDICATE STRATOCU SPREADING TO THE SSE INTO THIS AREA TODAY... AND MORNING SOUNDINGS AND TRAJECTORIES ALONG WITH SATELLITE IMAGERY SUPPORT A PERIOD OF PARTLY SUNNY TO MOSTLY CLOUDY SKIES OVER THE COASTAL PLAIN AND NORTHEAST PIEDMONT THROUGH THE REST OF THE DAY. OVER THE FAR WESTERN PIEDMONT... OROGRAPHICALLY ENHANCED CIRRUS IS LIKELY TO PERSIST FOR A FEW MORE HOURS GIVEN THAT OBSERVED AND FORECAST SOUNDINGS SHOW A FAVORABLE WIND PROFILE. THE THICKER CLOUDS IN THE NORTHEAST WILL IMPACT TEMPS... AS SUGGESTED BY THE LATEST HRRR OUTPUT... SUGGESTING HIGHS THERE IN THE LOWER 50S... WHEREAS AREAS FROM THE TRIANGLE AND TRIAD TO THE SOUTH AND SW SHOULD SEE HIGHS IN THE MID-UPPER 50S. THE MIXED LAYER NOTED IN FORECAST SOUNDINGS SUPPORTS GUSTS AROUND 20-25 MPH IN THE FAR NORTHEAST (NEAREST THE TIGHTER MSLP GRADIENT) BUT JUST 15-20 ELSEWHERE... BEFORE THE DEPARTURE OF THE STORM SYSTEM RESULTS IN A SLOW DIMINISHING OF WINDS TOWARD NIGHTFALL. -GIH TONIGHT...STRONG VORT MAX IN THE NW FLOW ALOFT WILL DROP SEWD FROM THE NORTHERN GREAT LAKES INTO NORTHERN MID ATLANTIC TONIGHT THEN OFF THE VIRGINIA CAPE BY EARLY FRI. THIS SYSTEM WILL BE MOISTURE STARVED SO EXPECT LITTLE IN THE MANNER OF CLOUDS. HOWEVER...THIS SYSTEM WILL MAINTAIN A FAIRLY TIGHT PRESSURE GRADIENT SO WINDS WILL MAINTAIN 5-9KTS OVERNIGHT. THIS MIXING WILL AID TO KEEP TEMPS UP A BIT. IF SFC WINDS DECOUPLE...MORE LIKELY IN THE WESTERN PIEDMONT...COULD SEE TEMPS TUMBLE 4-5 DEGREES COLDER THAN FORECAST. MIN TEMPS UPPER 20S WEST TO LOWER 30S COASTAL PLAIN. -WSS && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 300 AM THURSDAY... FRIDAY AND FRIDAY NIGHT...AS STRONG VORT EXITS OFF THE MID ATLANTIC COAST...LOW LEVEL FLOW WILL BECOME MORE N-NE. SOME MODELS (ESPECIALLY NAM) DEPICT MORE OF A FETCH OFF THE ATLANTIC WHILE THE GFS AND ECMWF MAINTAIN A NLY FLOW (MAINLY OVER LAND). CONSIDERING THE AMOUNT OF MOISTURE ON THE BACK SIDE OF THE DEEP LOW...NAM MAY BE ONTO SOMETHING. THUS HAVE INCREASED CLOUD COVERAGE IN THE EAST LATE FRI INTO FRIDAY NIGHT. WITH A FEW MORE CLOUDS EXPECTED NE VERSUS SW...SHOULD SEE COOLER MAX TEMPS NE AND WARMER SW. MAX TEMPS NEAR 50 NORTHERN COASTAL PLAIN TO MID-UPPER 50S SW. MIN TEMPS FRIDAY NIGHT HIGHLY DEPENDENT ON EXTENT OF CLOUD COVERAGE. USED A BLEND OF MOS GUIDANCE FOR MIN TEMPS. HOWEVER IF CLOUDS DO MATERIALIZE...MIN TEMPS WILL NEED TO BE ADJUSTED UP A FEW DEGREES. CONVERSELY...IF CLOUDS DO NOT FORM AND SFC WINDS DECOUPLE...MIN TEMPS WILL NEED TO BE ADJUSTED DOWN 4-5 DEGREES. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 250 AM THURSDAY... THIS WEEKEND: BENEATH A BUILDING AND SLOWLY PROGRESSIVE RIDGE ALOFT...1030 MB SURFACE HIGH PRESSURE WILL SPAN THE LENGTH OF THE EAST COAST. THE RIDGING WILL PROVIDE FOR GENERALLY CLEAR AND MODERATING CONDITIONS FOR CENTRAL NC...WITH THE ONLY APPRECIABLE CLOUD COVER...ASIDE FROM CIRRUS...LIKELY TO HOLD WEST OF THE YADKIN IN RETURN LOW LEVEL FLOW SUN NIGHT-MON MORNING. STEADILY RISING THICKNESSES SUGGEST HIGHS AROUND 60 DEGREES SAT...AND IN THE LOWER-MIDDLE 60S SUN. BELOW GUIDANCE LOWS IN THE 29 TO 34 DEGREE RANGE WITH EXCELLENT RADIATIONAL SAT NIGHT...AND ABOUT 10 DEGREES MILDER SUN NIGHT. MONDAY THROUGH WEDNESDAY: THE DEEP LAYER RIDGING WILL CONTINUE EASTWARD IN THE AFOREMENTIONED SLOWLY PROGRESSIVE FLOW...IN ADVANCE OF A COMPLEX TROUGH ALOFT OVER AND OFFSHORE THE PAC NW COAST THIS MORNING. MEDIUM RANGE GUIDANCE IS IN REASONABLY GOOD AGREEMENT REGARDING THE PROGRESSION OF THIS TROUGH AND ACCOMPANYING WET LOW LEVEL FRONTAL ZONE ACROSS CENTRAL NC MON NIGHT-TUE...WITH A PRECEDING RESIDUAL CAPPING INVERSION LIKELY TO HOLD THROUGH THE DAY MON. INHERENT UNCERTAINTY AT THIS TIME RANGE FAVORS HOLDING POP IN THE 50-60 PERCENT RANGE...BUT CATEGORICAL PROBABILITIES WILL ULTIMATELY BE WARRANTED WITH TIME GIVEN THE EXPECTED WIDE-OPEN AND STRONG GULF INFLOW INTO THE FRONTAL ZONE. POST-FRONTAL COOLER AND DRIER CONDITIONS WILL PREVAIL FOR MID-LATE WEEK. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 625 AM THURSDAY... VFR CONDITIONS ARE EXPECTED ACROSS CENTRAL NC TODAY THROUGH FRIDAY. A DEEP LOW PRESSURE SYSTEM OFFSHORE WILL CONTINUE TO INFLUENCE OUR SENSIBLE WEATHER. PRONOUNCED CYCLONIC FLOW WILL RESULT IN BREEZY CONDITIONS TODAY WITH FREQUENT GUSTS 20-25KTS...ESPECIALLY OVER THE COASTAL PLAIN (KRWI). NLY FLOW IN THE 925-850MB LAYER HAS ADVECTED MOISTURE INTO THE WESTERN PIEDMONT...RESULTING IN A DECK OF STRATUS BETWEEN 3500-4500FT. AS LOW LEVEL FLOW BACKS AND BECOMES NW...CLOUD COVERAGE WILL DIMINISH. OTHERWISE A DECK OF STRATOCU WILL DEVELOP LATER THIS MORNING WITH BASES BETWEEN 4000-5000FT. THIS CLOUD DECK SHOULD BE RELATIVELY THIN AND SHOULD DISSIPATE WITHIN A FEW HOURS AFTER SUNSET. HIGH PRESSURE WILL BEGIN TO EXERT ITS INFLUENCE ON OUR WEATHER FRIDAY AND MORE SO SATURDAY INTO SUNDAY AS THIS WEATHER FEATURE WILL EXTEND SW-NE ACROSS THE AREA. MAINLY CLEAR SKIES AND LIGHT WINDS WILL BE ASSOCIATED WITH THE HIGH. THE HIGH WILL DRIFT EAST MONDAY...SETTING UP A RETURN FLOW REGIME...LEADING TO MORE CLOUDS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD/WSS SHORT TERM...WSS LONG TERM...MWS AVIATION...WSS
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
300 PM EST THU MAR 7 2013 .SYNOPSIS... LOW PRESSURE OFF THE EAST COAST DRIFTS SLOWLY AWAY THROUGH FRIDAY...ALLOWING HIGH PRESSURE TO BUILD IN THIS WEEKEND. A COLD FRONT AND WAVE OF LOW PRESSURE MOVE THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH FRIDAY NIGHT/... STILL COULD SEE A PEAK OF SUN OR TWO INTO THE KANAWHA VALLEY THIS AFTERNOON...BUT CANNOT ELIMINATING THE LOW LEVEL MOISTURE IN PLACE DOWNWIND OF THE GREAT LAKES. RUC HAS THE STRATUS DECK THROUGH 05Z TONIGHT...AND OTHER MODELS DRYING OUT THE WESTERN LOWLANDS AFTER 06Z. THE SUN MAKES AN APPEARANCE FRIDAY WITH HIGH PRESSURE DRIFTING ACROSS THE SOUTHERN GREAT LAKES AND DRYING LOW LEVELS. NAM AT 925MB STILL HAS NORTHERLY FLOW AND SATURATION IN A LINGERING THERMAL TROUGH...SO KEPT THE CLOUDS IN PLACE OVER THE TYGART AND GREENBRIER VALLEYS. WILL SEE A SLOW IMPROVEMENT TO THE 850MB TEMPERATURES...BUT WILL NOT QUITE GET INTO THE EFFICIENT WARM UP WITH A NORTHERLY COMPONENT TO THE WIND AT THE SURFACE AN LOW LEVELS THROUGH 00Z SATURDAY. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... HIGH PRESSURE IS IN CONTROL AT THE SURFACE FOR THE FIRST HALF OF THE WEEKEND...WITH A RIDGE BUILDING IN ALOFT. THIS WILL SPELL ABOVE NORMAL AFTERNOON HIGHS ACROSS MUCH OF THE FORECAST AREA. HIGHS MAY BE TEMPERED A BIT BY LINGERING SNOW COVER IN THE NORTHERN MOUNTAINS OF WEST VIRGINIA SO STAY A BIT BELOW GUIDANCE THERE. MODEL TIMING A LITTLE DIFFERENT ON WHEN THE LEADING PRECIP AHEAD OF THE NEXT SYSTEM MAY ENTER OUR WESTERN ZONES. ONLY MADE LITTLE CHANGES FROM PREVIOUS POP FORECAST...WITH SLIGHT CHANCE POPS ENTERING FROM THE WEST SATURDAY AFTERNOON. DESPITE INCREASING HIGH CLOUDS...SUNDAY SHOULD BE THE WARMER DAY OF THE WEEKEND...WITH LOW TO MID 60S PRETTY WIDESPREAD ACROSS THE LOWER ELEVATIONS...AND UPPER 40S TO 50S IN THE MOUNTAINS AS SNOW PACK CONTINUES TO MELT. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... MOISTURE FROM THE LEADING EDGE OF THE NEXT FRONTAL SYSTEM WILL BEGIN TO SPREAD OVER THE WESTERN PORTIONS OF THE FORECAST AREA LATE SUNDAY NIGHT AS THE WEEKENDS UPPER LEVEL RIDGE SLIDES EAST INTO THE ATLANTIC. RAINFALL WILL BECOME MORE WIDESPREAD THROUGH THE DAY MONDAY AS A FRONTAL SYSTEM WITH A GOOD SOUTHERLY FETCH SHIFTS EAST. WITH TEMPERATURES REMAINING WARM DURING THIS TIME PERIOD WILL NEED TO WATCH THE FRONT CLOSELY FOR HYDRO CONCERNS. SO FAR MODELS ARE SHIFTING IT EAST QUICKLY ENOUGH TO KEEP PRECIPITATION AMOUNTS IN THE INCH RANGE BUT IF WAVES END UP FORMING ALONG THE FRONTAL BOUNDARY AND IT STALLS...THE NORTH TO SOUTH ORIENTATION OF THE SYSTEM WOULD BE FAVORABLE FOR PICKING A GOOD BIT MORE RAIN. AGAIN AT MOMENT IT DOES NOT LOOK LIKE THE FRONT WILL STALL BUT RATHER JUST SOMETHING TO WATCH. COOLER AIR WILL SWING DOWN BEHIND THE FRONTAL MIDWEEK BUT LOOKS FAR ENOUGH BEHIND THAT MOST OF THE LINGERING POST FRONTAL SHOWERS WILL BE OVER WITH BY THEN. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... LOW LEVEL MOISTURE WILL BE PERSISTENT INTO TONIGHT...AND CONTINUE TO HANG ON IN THE MOUNTAINS THROUGH THE TAF PERIOD. THIS WILL LEAD TO PRIMARILY MVFR CEILINGS AREA WIDE...WITH BRIEF VFR POSSIBLE THIS AFTERNOON FOR THE LOWLAND TERMINALS. CEILINGS TO LOWER A LITTLE BIT TONIGHT...AND WILL FLIRT WITH IFR ONCE AGAIN. BKW TO CONTINUE WITH LIFR CONDITIONS THROUGH THIS EVENING. NORTHWEST FLOW TO 10KTS...WITH THE OCCASIONAL GUST TO 15KTS...LIKELY THROUGH FRIDAY. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY... FORECAST CONFIDENCE...MEDIUM TO HIGH. ALTERNATE SCENARIOS: MAY NEED MORE IFR TONIGHT FROM LOWER CEILINGS. TIME OF LOW LEVEL MOISTURE EXIT AND CLOUD BREAK UP COULD VARY INTO TONIGHT AND FRIDAY. 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 20 21 22 23 00 01 02 03 04 05 06 07 EST 1HRLY 15 16 17 18 19 20 21 22 23 00 01 02 CRW CONSISTENCY H H H H H M M M H M L L HTS CONSISTENCY H H H H M M M M M H M M BKW CONSISTENCY L L H H M H M M M L L L EKN CONSISTENCY L L L L L L L L L L L L PKB CONSISTENCY H H H H H H H H M M H H CKB CONSISTENCY H H H H M M M M M H H L AFTER 18Z FRIDAY... NO WIDESPREAD IFR EXPECTED. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...MZ/26/JR NEAR TERM...26 SHORT TERM...MZ LONG TERM...JR AVIATION...26
AREA FORECAST DISCUSSION
NWS PORTLAND OR
850 PM PST WED MAR 6 2013 .SYNOPSIS...LOW PRESSURE ESSENTIALLY STALLED OVER THE PACIFIC NORTHWEST WILL LINGER AND WEAKEN THROUGH THURSDAY. THIS WILL KEEP THE WEATHER UNSETTLED WITH LIGHT TO MODERATE RAIN AT TIMES THROUGH THURSDAY. SNOW LEVELS WILL HOVER AROUND 2500 FT THROUGH THURSDAY NIGHT...THOUGH HEAVIER SHOWERS MAY TEMPORARILY LOWER THE SNOW LEVEL AT TIMES. THIS SYSTEM WILL SLOWLY MOVE EAST INTO THE ROCKIES... ALLOWING AN UPPER RIDGE TO BUILD IN FOR WARMER AND DRIER WEATHER FRIDAY AND POSSIBLY THROUGH THE WEEKEND. && .SHORT TERM...A BROAD UPPER LEVEL TROUGH JUST OFF THE OREGON COAST CONTINUES TO PRODUCE AN UNSETTLED AND MESSY PATTERN ACROSS THE PACIFIC NORTHWEST. THE MAIN UPPER LEVEL LOW SPINNING OFF THE SOUTH OREGON COAST WILL CONTINUE TO DROP SOUTHWARD PLACING MUCH OF WESTERN OREGON UNDER DEEP SOUTHWESTERLY FLOW. A DEFORMATION AXIS EXTENDING NORTHEASTWARD FROM THIS LOW PRESSURE TO THE MOUTH OF THE COLUMBIA RIVER AND PORTIONS OF SOUTHWEST WASHINGTON IS CURRENTLY PRODUCING STEADIER PRECIPITATION ACROSS PACIFIC COUNTY AND PRIMARILY POINTS NOW NORTH OF OUR CWA. THE GFS AND EC GENERALLY AGREE THIS DEFORMATION AXIS SHOULD GRADUALLY WEAKEN NEAR ITS CURRENT LOCATION OVER THE NEXT 12 HOURS. MEANWHILE...THE NAM ACTUALLY MOVES THIS BOUNDARY BACK TOWARDS THE SOUTHEAST OVERNIGHT TOWARDS PORTLAND...ALBEIT THE LATEST MODEL RUN HAS TRENDED TOWARDS THE GLOBAL MODELS. AS A RESULT...POPS WERE HEDGED HIGHEST TOWARDS ASTORIA AND THE WILLAPA HILLS OVERNIGHT INTO THURSDAY MORNING AS THIS FEATURE DECAYS IN PLACE. MEANWHILE...A RELATIVELY MOIST AND UNSTABLE AIRMASS IS PRODUCING ISOLATED TO SCATTERED SHOWERS OVER THE WILLAMETTE VALLEY THIS EVENING. OROGRAPHIC ASCENT INTO THE SOUTH WASHINGTON CASCADES HAS BEEN QUITE PRONOUNCED IN THE SOUTHWESTERLY FLOW AS SHOWERS CONTINUE TO DEVELOP RAPIDLY IN THE FOOTHILLS NORTHEAST OF VANCOUVER. MANY SITES ACROSS THE SOUTH WASHINGTON CASCADES HAVE ALREADY REACHED WINTER WX ADVISORY CRITERIA AND THE MODELS GENERALLY AGREE DECENT OROGRAPHICS WILL CONTINUE THROUGH ABOUT 12Z TONIGHT. AS A RESULT...WE WENT AHEAD AND ISSUED A WINTER WX ADVISORY. UPON FURTHER INSPECTION...RADAR RETURNS HAVE LET UP AT LEAST A BIT IN THE LAST HOUR. THIS IS LIKELY IN RESPONSE TO THE BEST OMEGA BECOMING INCREASINGLY CONFINED TO BELOW THE DENDRITIC LAYER AS SEEN IN THE LATEST NAM AND RUC CROSS SECTIONS. AS A RESULT...CONFIDENCE IS LOW THAT ANOTHER 6 INCHES WILL FALL TONIGHT...BUT WILL KEEP THE ADVISORY GOING FOR NOW. ALSO WENT AHEAD AND REMOVED THE MENTION OF THUNDER FROM THE CENTRAL OREGON COAST AS CONVECTION HAS REMAINED TOO SHALLOW TO PRODUCE ENOUGH CHARGE SEPARATION TO GENERATE LIGHTNING. /NEUMAN PREVIOUS DISCUSSION BELOW...BELIEVE MODELS ARE A LITTLE OVERDONE ON CLOUD COVER THURSDAY...BUT NONETHELESS IT SHOULD BE A MOSTLY CLOUDY DAY WITH PLENTY OF STRATOCUMULUS. THERE PROBABLY WILL BE ENOUGH SUN BREAKS TO GENERATE ENOUGH SHALLOW INSTABILITY FOR MORE SHOWERS THURSDAY...ESPECIALLY OVER THE HIGHER TERRAIN. WITH FREEZING LEVELS LOW...THE MORE VIGOROUS SHOWERS COULD PRODUCE SMALL HAIL. HOWEVER THESE SHOWERS SHOULD BE CAPPED AROUND 10-12 KFT...WHICH SHOULD LIMIT THE THREAT FOR THUNDER. CLEARING TREND BEGINS IN EARNEST THU NIGHT...WITH A CHILLY NIGHT EXPECTED FOR THE VALLEYS. AFTER STARTING OFF WITH SOME PATCHES OF FOG...FRIDAY WILL BE PARTLY TO MOSTLY SUNNY ASIDE FROM SOME MOUNTAIN CLOUDS AND ISOLATED SHOWERS. UPPER LEVEL RIDGING BUILDS FRI NIGHT AND SATURDAY...WITH MORE NIGHT/MORNING FOG POSSIBLE. SINCE THIS RIDGE IS RATHER FLAT...THERE COULD BE SOME HIGH CLOUDS ESPECIALLY IN THE NORTHERN ZONES...OTHERWISE MILD AND SUNNY CONDITIONS EXPECTED FOR SATURDAY. WEAGLE .LONG TERM...SATURDAY EVENING THROUGH TUESDAY...A BREAK IN THE WEATHER IS EXPECTED FOR THE WEEKEND AS A FLAT UPPER LEVEL RIDGE BUILDS OVER THE AREA. MODELS AGREE ON KEEPING ANY SYSTEMS TO THE NORTH THROUGH SUNDAY...THOUGH WITH THE FLAT RIDGE OVER THE AREA AND WESTERLY FLOW ALOFT BRINGING MOISTURE INTO WASHINGTON...THE PRECIPITATION IS NEVER VERY DISTANT FROM OUR AREA. CURRENTLY MODELS AGREE ON LIMITING PRECIPITATION GENERALLY TO WASHINGTON. SOUTHWEST WASHINGTON ISNT LIKELY TO SEE MUCH PRECIPITATION UNLESS THE JET STREAM SLIPS SOUTHWARD A BIT. MODEL CONSENSUS IS TO DROP THE RIDGE SOUTH BY LATE TUESDAY AND BRING A CHANCE OF RAIN TO THE AREA. A STRONGER TROUGH FOLLOWS SOMETIME NEAR THE END OF THE WEEK. KWELSON && .AVIATION...THE STEADY RAIN HAS MOVED NORTH INTO WESTERN WASHINGTON WITH SCATTERED SHOWERS NOW STREAMING INTO NW OREGON. COASTAL AREAS LIKELY TO REMAIN IN MVFR CIGS TONIGHT AND THU MORNING BUT MODEL TRENDS INDICATE LOW VFR IS LIKELY THU AFTERNOON. INLAND AREAS SHOULD REMAIN VFR THROUGH 10Z THU THEN MVFR WITH CIGS AROUND 2000 TO 2500 FT BECOMING MORE COMMON. BUT THAT SHOULD LAST THROUGH ABOUT 17Z TO 20Z THU. THE COAST RANGE AND CASCADES WILL BE FREQUENTLY OBSCURED THROUGH AROUND 06Z THU...WITH THE S WA CASCADES AND FAR N OREGON CASCADES OBSCURED THROUGH AT LEAST 18Z THU. KPDX AND APPROACHES...PREDOMINANT VFR EXPECTED THROUGH ABOUT 10Z. MOIST BOUNDARY LAYER AND INCREASING STABILITY OVERNIGHT SHOULD LEAD TO MVFR CIGS AROUND 10Z AND CONTINUING UNTIL 18Z THU OR SO. VFR EXPECTED AFTER THAT AND LIKELY CONTINUING THROUGH 06Z FRI. && .MARINE...SURFACE TROUGH LAY NORTH TO SOUTH ACROSS THE WATERS TONIGHT. A SMALL SURFACE LOW OFF THE SOUTH COAST IS BRINGING ADVISORY WINDS TO THE CENTRAL COASTAL WATERS. MODELS ARE IN SOME DISAGREEMENT WITH THE EVOLUTION OF THE TROUGH AND LOW OVERNIGHT INTO THU MORNING. FOR NOW WILL KEEP THE ADVISORY FOR WINDS THROUGH 7 AM THU...BUT IT COULD LAST A LITTLE LONGER. SEAS WILL HOVER IN THE 5 TO 7 FOOT RANGE THROUGH FRI NIGHT. HOWEVER SEAS WILL BE CLOSE TO 10 FT OVER THE CENTRAL WATERS MAINLY DUE TO SHORTER PERIOD WIND WAVES. LATEST MODEL GUIDANCE SHOWS A SET OF LONGER-PERIOD SEAS REACHING THE WATERS SATURDAY...BUT NOT QUITE UP TO 10 FT. && .PQR WATCHES/WARNINGS/ADVISORIES... OR...NONE. WA...WINTER WEATHER ADVISORY UNTIL 4 AM PST THURSDAY FOR SOUTH WASHINGTON CASCADES. PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 7 AM PST THURSDAY FOR COASTAL WATERS FROM CASCADE HEAD OR TO FLORENCE OR OUT 60 NM. && $$ 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 FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1042 AM MST THU MAR 7 2013 .UPDATE... ISSUED AT 830 AM MST THU MAR 7 2013 15Z SURFACE ANALYSIS HAD WEAK LOW OVER NORTHEAST WY WITH GENTLE COOL FRONT/TROUGH FROM CENTRAL MT INTO SOUTHWEST SD. MID/HIGH CLOUDS STREAMING OVER CWA ON 90KT UPPER LEVEL JET...BUT THEY ARE PARTIALLY TRANSPARENT. 12Z RAP MESHES WELL WITH CURRENT TRENDS. WILL TWEAK TEMPERATURES WEST OF THE FRONT A COUPLE OF DEGREES UP BASED ON 12Z RAP/KUNR SOUNDING...AND EAST OF THE FRONT A TAD LOWER GIVEN UPSTREAM SURFACE TRAJECTORIES. REST OF FORECAST IN GOOD SHAPE. && .SHORT TERM...(TODAY THROUGH FRIDAY NIGHT) ISSUED AT 305 AM MST THU MAR 7 2013 WESTERN CONUS TROUGHING CONTINUES...SUPPORTING FAST DISTURBED OVER THE LOCAL REGION. ASSOCIATED ADVECTING IMPULSE CONTINUES TO PROPAGATE ENE ACROSS THE NORTHERN PLAINS...WITH AN ASSOCIATED LL TROUGH REFLECTION. THIS IMPULSE WILL CONTINUE EAST TODAY...SUPPORTING WEAK CAA IN IT/S WAKE. FLOW WILL QUICKLY RESPOND TO THE NEXT ADVANCING SHORTWAVE TOUGH AS THE MAIN WESTERN CONUS LONG WAVE TROUGH CONTINUES TO DIG SOUTH INTO THE SW CONUS. WAA WILL AGAIN SPREAD OVER THE REGION FRIDAY AHEAD OF THE NEXT ADVANCING DISTURBANCE...WITH LL FLOW RESPONDING TO ONGOING PRESSURE FALLS. WEAK DEFORMATION ZONE WILL DEVELOP OVER PORTIONS OF NE WY AND MT...AND EAST INTO NORTH DAKOTA....POSSIBLY SUPPORTING SOME LIGHT PRECIP ACTIVITY LATE FRIDAY MORNING INTO FRIDAY AFTERNOON THERE. LATEST GUIDANCE CONTINUES TO TREND THIS AREA OF LIFT NW...WITH ONLY LOW TO MID RANGE CHANCE POPS RETAINED OVER THE NW FA. OTHERWISE...ATTENTION TURNS TOWARD INCREASING LARGE SCALE ASCENT WITH THE AFOREMENTIONED LEAD SHORTWAVE TROUGH. INCREASING LL MOISTURE PER SE LL FLOW WILL SUPPORT SUFFICIENT LL MOISTURE FLUX FOR RAIN/SNOW/WITH THE POTENTIAL FOR FREEZING RAIN REMAINING OVER SCENTRAL SD INTO CENTRAL SD...GIVEN A STRONG ELEVATED WARM TONGUE ADVANCING NW AHEAD OF THIS WAVE. MEANWHILE...AN EXPECTED NORTHERN STREAM TROUGH WILL QUICKLY ADVECT INTO THE NORTHERN PLAINS LATER FRIDAY NIGHT...SUPPORTING INCREASING LL CAA AND INDUCED LL PRESSURE FALLS. THIS WAVE AND ASSOCIATED COLD FRONT WILL INTRODUCE ENOUGH COLD AIR TO END ALL MIXED PRECIP CHANCES SAT MORNING...WITH SNOW BEING THE DOMINANT PRECIP TYPE ALL PLACES AS THE MAIN SW CONUS UPPER TROUGH BEGINS TO EJECT TOWARD THE REGION. FORECAST MODELS ARE STILL WAVERING ON THE EXACT DETAILS PER THIS EVOLUTION...WITH STILL MANY DETAILS TO BE WORKED OUT. HOWEVER...CONFIDENCE HAS INCREASED THAT THERE WILL BE A PERIOD OF MIXED PRECIP IN SCENTRAL SD FRIDAY NIGHT. STRONG WARM NOSE /2-3C/ IN A THETA-E ADV REGIME WITH INCREASING LSA WILL BE MORE THAN AMPLE TO SUPPORT PRECIP DEVELOPMENT. FORECAST MODELS SUGGEST UP TO A QUARTER INCH QPF IN FAR SCENTRAL SD...MAINLY RAIN AT FIRST WITH A PERIOD OF ICING LIKELY LATER /WHICH IS IN LINE WITH CURRENT SREF PROGS/. ATTM IT DOES NOT APPEAR TO THAT SIG ICING IS EXPECTED GIVEN A RATHER WARM BL THROUGH FRI NIGHT. HOWEVER...SOME SOLUTIONS SUGGEST UP TO A TENTH OF INCH OF ICE ACCUMS IS POSSIBLE ESP AROUND THE WINNER AREA. THIS WILL NEED TO BE WATCHED. SMALL ADJUSTMENT MADE TO HIGH TEMPS...WHICH WILL BE TRICKY TODAY GIVEN THE ADVANCING COLD FRONT AND ASSOCIATED CAA TIMING. STILL EXPECT 50S AND SOME LOWER 60S WILL BE POSSIBLE IN SW SD...WITH TEMPS ONLY REACHING THE 40S OVER NW SD AND NE WY. COOLER TEMPS EXPECTED FRI. .LONG TERM...(SATURDAY THROUGH WEDNESDAY) ISSUED AT 305 AM MST THU MAR 7 2013 LARGE UPPER LEVEL TROF WILL CROSS THE NORTHERN PLAINS THIS WEEKEND WITH A RIDGE BUILDING IN FOR EARLY NEXT WEEK. POTENT SYSTEM WITHIN THE TROF WILL CROSS THE CENTRAL PLAINS ON SATURDAY AND SUNDAY...WITH THE NORTHERN EDGE OF THE SYSTEM BRINGING ACCUMULATING SNOWS TO SOUTHERN PORTIONS OF THE FORECAST AREA. LATEST MODEL RUNS CONTINUE TO SHOW UPPER LOW SWINGING THROUGH THE FOUR CORNERS AREA VERY EARLY SATURDAY MORNING...AND TRACKING EAST-NORTHEASTWARD THROUGH THE WEEKEND. MID LEVEL LOW DEVELOPS ACROSS EASTERN COLORADO BY MIDDAY SATURDAY AS NORTHERN EDGE OF PRECIP SHIELD SHIFTS NORTH INTO THE AREA. AMPLE MOISTURE AND NORTHERLY BOUNDARY LAYER FLOW WILL ALSO BRING UPSLOPE SNOW TO THE NORTHERN BLACK HILLS AREA SATURDAY AND SATURDAY EVENING. SYSTEM QUICKLY SHIFTS EAST SATURDAY NIGHT...WITH SNOW TAPERING OFF BY EARLY SUNDAY MORNING. THE BEST CHANCES FOR SIGNIFICANT PCPN AMOUNTS WILL BE ACROSS FAR SOUTHERN SD...ESPECIALLY SOUTH CENTRAL SD...AND ACROSS THE NORTHERN BLACK HILLS. UP TO 6 INCHES OF SNOWFALL WILL BE POSSIBLE IN THESE AREAS. BEYOND THAT...TEMPERATURES WILL GRADUALLY WARM INTO EARLY NEXT WEEK AS RIDGE BUILDS OVER THE WESTERN CONUS. MOSTLY DRY WEATHER IS EXPECTED ACROSS THE AREA...BUT WILL KEEP SOME LOW CHANCES FOR RAIN AND SNOW SHOWERS FOR MONDAY AFTERNOON INTO TUESDAY ACROSS PORTIONS OF NORTHEASTERN WY AND INTO THE BLACK HILLS AS WEAK UPPER LEVEL ENERGY PASSES OVER THE RIDGE. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1041 AM MST THU MAR 7 2013 VFR CONDITIONS ARE GENERALLY EXPECTED THROUGH FRIDAY MORNING. THERE IS A CHANCE FOR SNOW SHOWERS LATE TONIGHT AND FRIDAY MORNING ACROSS FAR NORTHEASTERN WY INTO FAR NORTHWESTERN SD...WITH LOCAL MVFR CONDITIONS EXPECTED. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ UPDATE...HELGESON SHORT TERM...JC LONG TERM...15 AVIATION...26
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
834 AM MST THU MAR 7 2013 .UPDATE... ISSUED AT 830 AM MST THU MAR 7 2013 15Z SURFACE ANALYSIS HAD WEAK LOW OVER NORTHEAST WY WITH GENTLE COOL FRONT/TROUGH FROM CENTRAL MT INTO SOUTHWEST SD. MID/HIGH CLOUDS STREAMING OVER CWA ON 90KT UPPER LEVEL JET...BUT THEY ARE PARTIALLY TRANSPARENT. 12Z RAP MESHES WELL WITH CURRENT TRENDS. WILL TWEAK TEMPERATURES WEST OF THE FRONT A COUPLE OF DEGREES UP BASED ON 12Z RAP/KUNR SOUNDING...AND EAST OF THE FRONT A TAD LOWER GIVEN UPSTREAM SURFACE TRAJECTORIES. REST OF FORECAST IN GOOD SHAPE. && .SHORT TERM...(TODAY THROUGH FRIDAY NIGHT) ISSUED AT 305 AM MST THU MAR 7 2013 WESTERN CONUS TROUGHING CONTINUES...SUPPORTING FAST DISTURBED OVER THE LOCAL REGION. ASSOCIATED ADVECTING IMPULSE CONTINUES TO PROPAGATE ENE ACROSS THE NORTHERN PLAINS...WITH AN ASSOCIATED LL TROUGH REFLECTION. THIS IMPULSE WILL CONTINUE EAST TODAY...SUPPORTING WEAK CAA IN IT/S WAKE. FLOW WILL QUICKLY RESPOND TO THE NEXT ADVANCING SHORTWAVE TOUGH AS THE MAIN WESTERN CONUS LONG WAVE TROUGH CONTINUES TO DIG SOUTH INTO THE SW CONUS. WAA WILL AGAIN SPREAD OVER THE REGION FRIDAY AHEAD OF THE NEXT ADVANCING DISTURBANCE...WITH LL FLOW RESPONDING TO ONGOING PRESSURE FALLS. WEAK DEFORMATION ZONE WILL DEVELOP OVER PORTIONS OF NE WY AND MT...AND EAST INTO NORTH DAKOTA....POSSIBLY SUPPORTING SOME LIGHT PRECIP ACTIVITY LATE FRIDAY MORNING INTO FRIDAY AFTERNOON THERE. LATEST GUIDANCE CONTINUES TO TREND THIS AREA OF LIFT NW...WITH ONLY LOW TO MID RANGE CHANCE POPS RETAINED OVER THE NW FA. OTHERWISE...ATTENTION TURNS TOWARD INCREASING LARGE SCALE ASCENT WITH THE AFOREMENTIONED LEAD SHORTWAVE TROUGH. INCREASING LL MOISTURE PER SE LL FLOW WILL SUPPORT SUFFICIENT LL MOISTURE FLUX FOR RAIN/SNOW/WITH THE POTENTIAL FOR FREEZING RAIN REMAINING OVER SCENTRAL SD INTO CENTRAL SD...GIVEN A STRONG ELEVATED WARM TONGUE ADVANCING NW AHEAD OF THIS WAVE. MEANWHILE...AN EXPECTED NORTHERN STREAM TROUGH WILL QUICKLY ADVECT INTO THE NORTHERN PLAINS LATER FRIDAY NIGHT...SUPPORTING INCREASING LL CAA AND INDUCED LL PRESSURE FALLS. THIS WAVE AND ASSOCIATED COLD FRONT WILL INTRODUCE ENOUGH COLD AIR TO END ALL MIXED PRECIP CHANCES SAT MORNING...WITH SNOW BEING THE DOMINANT PRECIP TYPE ALL PLACES AS THE MAIN SW CONUS UPPER TROUGH BEGINS TO EJECT TOWARD THE REGION. FORECAST MODELS ARE STILL WAVERING ON THE EXACT DETAILS PER THIS EVOLUTION...WITH STILL MANY DETAILS TO BE WORKED OUT. HOWEVER...CONFIDENCE HAS INCREASED THAT THERE WILL BE A PERIOD OF MIXED PRECIP IN SCENTRAL SD FRIDAY NIGHT. STRONG WARM NOSE /2-3C/ IN A THETA-E ADV REGIME WITH INCREASING LSA WILL BE MORE THAN AMPLE TO SUPPORT PRECIP DEVELOPMENT. FORECAST MODELS SUGGEST UP TO A QUARTER INCH QPF IN FAR SCENTRAL SD...MAINLY RAIN AT FIRST WITH A PERIOD OF ICING LIKELY LATER /WHICH IS IN LINE WITH CURRENT SREF PROGS/. ATTM IT DOES NOT APPEAR TO THAT SIG ICING IS EXPECTED GIVEN A RATHER WARM BL THROUGH FRI NIGHT. HOWEVER...SOME SOLUTIONS SUGGEST UP TO A TENTH OF INCH OF ICE ACCUMS IS POSSIBLE ESP AROUND THE WINNER AREA. THIS WILL NEED TO BE WATCHED. SMALL ADJUSTMENT MADE TO HIGH TEMPS...WHICH WILL BE TRICKY TODAY GIVEN THE ADVANCING COLD FRONT AND ASSOCIATED CAA TIMING. STILL EXPECT 50S AND SOME LOWER 60S WILL BE POSSIBLE IN SW SD...WITH TEMPS ONLY REACHING THE 40S OVER NW SD AND NE WY. COOLER TEMPS EXPECTED FRI. .LONG TERM...(SATURDAY THROUGH WEDNESDAY) ISSUED AT 305 AM MST THU MAR 7 2013 LARGE UPPER LEVEL TROF WILL CROSS THE NORTHERN PLAINS THIS WEEKEND WITH A RIDGE BUILDING IN FOR EARLY NEXT WEEK. POTENT SYSTEM WITHIN THE TROF WILL CROSS THE CENTRAL PLAINS ON SATURDAY AND SUNDAY...WITH THE NORTHERN EDGE OF THE SYSTEM BRINGING ACCUMULATING SNOWS TO SOUTHERN PORTIONS OF THE FORECAST AREA. LATEST MODEL RUNS CONTINUE TO SHOW UPPER LOW SWINGING THROUGH THE FOUR CORNERS AREA VERY EARLY SATURDAY MORNING...AND TRACKING EAST-NORTHEASTWARD THROUGH THE WEEKEND. MID LEVEL LOW DEVELOPS ACROSS EASTERN COLORADO BY MIDDAY SATURDAY AS NORTHERN EDGE OF PRECIP SHIELD SHIFTS NORTH INTO THE AREA. AMPLE MOISTURE AND NORTHERLY BOUNDARY LAYER FLOW WILL ALSO BRING UPSLOPE SNOW TO THE NORTHERN BLACK HILLS AREA SATURDAY AND SATURDAY EVENING. SYSTEM QUICKLY SHIFTS EAST SATURDAY NIGHT...WITH SNOW TAPERING OFF BY EARLY SUNDAY MORNING. THE BEST CHANCES FOR SIGNIFICANT PCPN AMOUNTS WILL BE ACROSS FAR SOUTHERN SD...ESPECIALLY SOUTH CENTRAL SD...AND ACROSS THE NORTHERN BLACK HILLS. UP TO 6 INCHES OF SNOWFALL WILL BE POSSIBLE IN THESE AREAS. BEYOND THAT...TEMPERATURES WILL GRADUALLY WARM INTO EARLY NEXT WEEK AS RIDGE BUILDS OVER THE WESTERN CONUS. MOSTLY DRY WEATHER IS EXPECTED ACROSS THE AREA...BUT WILL KEEP SOME LOW CHANCES FOR RAIN AND SNOW SHOWERS FOR MONDAY AFTERNOON INTO TUESDAY ACROSS PORTIONS OF NORTHEASTERN WY AND INTO THE BLACK HILLS AS WEAK UPPER LEVEL ENERGY PASSES OVER THE RIDGE. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 305 AM MST THU MAR 7 2013 VFR CONDITIONS ARE EXPECTED THROUGH FRIDAY MORNING. THE EXCEPTION WILL BE ACROSS PARTS OF NORTHEAST WYOMING...WHERE SOME LIGHT SNOW SHOWERS WILL BE POSSIBLE AFTER MIDNIGHT. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ UPDATE...HELGESON SHORT TERM...JC LONG TERM...15 AVIATION...15
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1152 AM CST THU MAR 7 2013 .UPDATE...FOR 18Z TAFS. && .AVIATION... MVFR STRATUS DECK CONTINUES TO LINGER ACROSS THE FORECAST AREA. CLEARING SHOWING UP ON VISIBILE SATELLITE IN SOUTHERN COUNTIES. LOOK FOR CLEARING SKIES TO CONTINUE THROUGH 00Z. WITH LOW LEVEL MOISTURE NOT MIXING OUT LOOK FOR SCT CU AT ALL TERMINALS THIS AFTERNOON. LATE TONIGHT MVFR CONDITIONS WILL REAPPEAR FOR BNA AND CKV AROUND 06Z. MVFR TO IFR CONDITIONS WILL TAKE PLACE AROUND CSV. 72/MD && .PREV DISCUSSION... /ISSUED 1124 AM CST THU MAR 7 2013/ UPDATE... LOW LEVEL MOISTURE IS PREVENTING TEMPERATURES FROM RISING THIS MORNING AS PREVIOUSLY FORECAST. NEWEST RUC AND HRRR INDICATE THIS CLOUD COVER SHOULD ERODE OVER THE NEXT FEW HOURS AND TEMPERATURES WILL BEGIN TO RISE MORE RAPIDLY AT THAT POINT. HAVE LOWERED HIGHS A FEW DEGREES BASED OFF THIS SKY TREND AND EDITED SKY GRIDS TO REFLECT THE LATEST RUC DEPICTION. PREV DISCUSSION... /ISSUED 526 AM CST THU MAR 7 2013/ UPDATE...FOR 12Z AVIATION FORECAST AVIATION... LOW DECK REMAINS ACROSS MUCH OF MID STATE EXCEPT FOR SOUTHWEST CORNER. SHORT RANGE MODELS BEGIN ERODING LOW DECK FROM SOUTHWEST AFTER 12Z. I HAVE CLARKSVILLE SCATTERED AT 25 HNDRD BY 15Z WITH NASHVILLE GOING SCATTERED AT SAME LEVEL AROUND 16Z. NOT REAL OPTIMISTIC ABOUT CROSSVILLE SCATTERING OUT DURING THE DAY BUT SINCE MOIST LAYER IS QUITE THIN WOULD THINK IT WOULD MIX OUT DURING THE DAY AT SOME POINT. I WENT WITH LOW DECK SCATTERING OUT AROUND 20Z AT CROSSVILLE. BOYD PREV DISCUSSION... /ISSUED 211 AM CST THU MAR 7 2013/ DISCUSSION...SURFACE HIGH PRESSURE REMAINS SITUATED WEST OF MIDDLE TENNESSEE WITH STUBBORN LOW CLOUDS STILL COVERING MOST OF THE MID STATE. EVENING SOUNDING FROM OHX SHOWS THE CLOUD DECK ONLY AROUND 1400 FT THICK, SO MORNING SUN SHOULD PROVIDE ENOUGH HEAT TO QUICKLY ERODE CLOUD COVER AND FINALLY SCATTER US OUT. AFTERWARDS, LOOK FOR SEVERAL DAYS OF MILD, QUIET WEATHER, WITH SIGNIFICANTLY WARMER TEMPERATURES IN STORE THIS WEEKEND. SURFACE RIDGE WILL LIKELY SLIDE EAST OF MIDDLE TENNESSEE FRIDAY OR FRIDAY NIGHT, WITH A SW FLOW DEVELOPING ALOFT. NEXT ACTIVE WEATHER SYSTEM WILL MOVE IN SUNDAY NIGHT, WITH THUNDERSTORMS ON MONDAY, ALTHOUGH MIDDLE TENNESSEE IS NOWHERE NEAR ANY SEVERE WEATHER RISK AREA THROUGH DAY 8. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 72
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1124 AM CST THU MAR 7 2013 .UPDATE... LOW LEVEL MOISTURE IS PREVENTING TEMPERATURES FROM RISING THIS MORNING AS PREVIOUSLY FORECAST. NEWEST RUC AND HRRR INDICATE THIS CLOUD COVER SHOULD ERODE OVER THE NEXT FEW HOURS AND TEMPERATURES WILL BEGIN TO RISE MORE RAPIDLY AT THAT POINT. HAVE LOWERED HIGHS A FEW DEGREES BASED OFF THIS SKY TREND AND EDITED SKY GRIDS TO REFLECT THE LATEST RUC DEPICTION. && .PREV DISCUSSION... /ISSUED 526 AM CST THU MAR 7 2013/ UPDATE...FOR 12Z AVIATION FORECAST AVIATION... LOW DECK REMAINS ACROSS MUCH OF MID STATE EXCEPT FOR SOUTHWEST CORNER. SHORT RANGE MODELS BEGIN ERODING LOW DECK FROM SOUTHWEST AFTER 12Z. I HAVE CLARKSVILLE SCATTERED AT 25 HNDRD BY 15Z WITH NASHVILLE GOING SCATTERED AT SAME LEVEL AROUND 16Z. NOT REAL OPTIMISTIC ABOUT CROSSVILLE SCATTERING OUT DURING THE DAY BUT SINCE MOIST LAYER IS QUITE THIN WOULD THINK IT WOULD MIX OUT DURING THE DAY AT SOME POINT. I WENT WITH LOW DECK SCATTERING OUT AROUND 20Z AT CROSSVILLE. BOYD PREV DISCUSSION... /ISSUED 211 AM CST THU MAR 7 2013/ DISCUSSION...SURFACE HIGH PRESSURE REMAINS SITUATED WEST OF MIDDLE TENNESSEE WITH STUBBORN LOW CLOUDS STILL COVERING MOST OF THE MID STATE. EVENING SOUNDING FROM OHX SHOWS THE CLOUD DECK ONLY AROUND 1400 FT THICK, SO MORNING SUN SHOULD PROVIDE ENOUGH HEAT TO QUICKLY ERODE CLOUD COVER AND FINALLY SCATTER US OUT. AFTERWARDS, LOOK FOR SEVERAL DAYS OF MILD, QUIET WEATHER, WITH SIGNIFICANTLY WARMER TEMPERATURES IN STORE THIS WEEKEND. SURFACE RIDGE WILL LIKELY SLIDE EAST OF MIDDLE TENNESSEE FRIDAY OR FRIDAY NIGHT, WITH A SW FLOW DEVELOPING ALOFT. NEXT ACTIVE WEATHER SYSTEM WILL MOVE IN SUNDAY NIGHT, WITH THUNDERSTORMS ON MONDAY, ALTHOUGH MIDDLE TENNESSEE IS NOWHERE NEAR ANY SEVERE WEATHER RISK AREA THROUGH DAY 8. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ TB12
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SYNOPSIS... ISSUED AT 240 PM CST THU MAR 7 2013 SEASONABLE TEMPERATURES...WITH THE NEXT CHANCE FOR SIGNIFICANT PRECIPITATION COMING DURING THE WEEKEND. AMPLIFIED SPLIT FLOW REGIME IN PLACE ACRS NOAM. THAT WL PERSIST THROUGH THE WEEKND AS STG SRN STREAM TROF MIGRATES EWD ACRS THE COUNTRY. THE TREND NEXT WK WL BE FOR THE FLOW TO BECOME MORE CONSOLIDATED AND LOSE AMPLITUDE. THE PATTERN WILL NOT SUPPORT ANY SIG COLD INTRUSIONS INTO THE AREA...SO TEMPS SHOULD BE NR OR A LITTLE ABV NORMAL FOR THE MOST PART. MAIN PCPN EVENT WL BE WITH THE CYCLONE CROSSING THE RGN THIS WEEKEND...WITH AMNTS PROBABLY ENDING UP NR OR A LITTLE ABV NORMAL. && .SHORT TERM...TONIGHT AND FRIDAY ISSUED AT 240 PM CST THU MAR 7 2013 LOW CLDS OFF LAKE SUPERIOR PROVED TOUGH TO DISLODGE FM NRN WI THIS MORNING. BUT MARCH SUNSHINE WAS ABLE TO HELP MIXING WORK THROUGH THE CLOUD LAYER...WITH ONLY SCT LOW CLDS NOW REMAINING. HIGH AND MIDDLE CLDS WERE STREAMING IN FM THE W...AND WL BE WORKING ACRS THE AREA TNGT. SFC RIDGE WL BE RIGHT ACRS THE AREA...SO WINDS WL BE LIGHT. COUNTING ON HIGH AND MIDDLE CLDS TO KEEP FG FROM GETTING OUT OF HAND. CONTD WITH PREV FCST OF JUST HAVING PATCHY FOG DEVELOPING AFTER MIDNIGHT...AND CONTG INTO FRI MORNING. ALSO COUNTING ON CLDS KEEPING TEMPS FROM GOING INTO FREE FALL. BLENDED THE MIN OF THE VARIOUS GUID PRODUCTS WITH THE WITH ECMWF AND BIAS-CORRECTED ECMWF...WHICH HAVE BEEN PERFORMING WELL LATELY. THE RESULT WAS A LOWERING OF THE MINS IN MOST AREAS BY A FEW DEGREES. QUIET WX WL CONT FRIDAY. TEMPS SHOULD BE A FEW DEGREES WARMER THAN TDA. .LONG TERM...FRIDAY NIGHT THROUGH THURSDAY ISSUED AT 240 PM CST THU MAR 7 2013 COMPLEX WEATHER PATTERN TAKING SHAPE ACROSS THE CONUS DURING THE EXTENDED PERIOD. ALREADY NEED TO DEAL WITH APPROACHING NRN STREAM SHORTWAVE TROF/CDFNT FRI NGT/SAT WITH PCPN TYPE ISSUES ONGOING. THIS WL BE FOLLOWED BY THE WEAKENING SRN STREAM UPR LOW/ SFC WAVE ON THE CDFNT LIFTING NE SUNDAY NGT/MON. THERE ARE THEN TIMING ISSUES WITH REGARDS TO A NRN STREAM CLIPPER SYSTEM AROUND TUE AND FINALLY THERE ARE QUESTIONS AS TO THE OVERALL ORIENTATION OF THE MEAN FLOW BY THE MIDDLE OF NEXT WEEK. THE ONLY WEATHER ELEMENT THAT LOOKS FAIRLY STABLE WL BE TEMPS WHICH APPEAR TO BE CLOSE TO NORMAL. EVEN AT THIS LATE DATE...THE MDLS DISAGREE ON WHEN TO BRING PCPN INTO NE WI STARTING LATE FRI NGT. THE NAM IS NOW SLOWER AND THE GFS IS NOW FASTER. THE ONLY COMMON GROUND IS THAT THE HEAVIER PCPN WL STILL BE TO OUR WEST AND SW FRI NGT ALONG A NE EXTENDED INVERTED SFC TROF RUNNING FROM WRN NEBRASKA TO CNTRL MN. CLOUDS WL STEADILY THICKEN THRU THE NGT AS A 40-50 KT S-SW LOW-LEVEL JET BRINGS GULF MOISTURE NWD INTO THE WRN GREAT LAKES. EXPECT TO SEE THE LEADING EDGE OF PCPN TO REACH CNTRL WI TOWARD DAYBREAK AND WITH SFC TEMPS STIL EXPECTED TO BE BELOW FREEZING...THIS LEADS TO THE POSSIBILITY OF MIXED PCPN AS WARMER AIR ALOFT ARRIVES. FCST SOUNDINGS INDICATE THAT N-CNTRL WI WOULD REMAIN ALL SNOW...BUT WITH TEMPS JUST ABOVE THE SFC CREEPING ABOVE 0C...CNTRL WI MAY SEE MORE OF A SNOW/SLEET COMBINATION. THE INVERTED SFC TROF IS PROGGED TO REMAIN WELL TO OUR WEST ON SAT... HOWEVER THE COMBINATION OF A LEAD SHORTWAVE EJECTED NEWD FROM THE SRN ROCKIES UPR LOW AND STRONG ISEN LIFT...WL BRING PCPN TO ALL OF NE WI. PCPN TYPE REMAINS THE BIGGEST FCST CHALLENGE AS SFC TEMPS STRUGGLE TO GET ABOVE THE FREEZING MARK SAT MORNING. SOUNDINGS CONT TO SHOW A WARM LAYER JUST SLIGHTLY ABOVE 0C WHICH WOULD INDICATE A MIXED PCPN POTENTIAL FOR ALL BUT THE LAKESHORE WHERE SE WINDS TO KEEP ANY PCPN MORE RAIN. BY SAT AFTERNOON...CNTRL/E-CNTRL WI WARM UP SUFFICIENTLY ENUF TO BRING MAINLY RAIN TO THIS PART OF THE FCST AREA. NRN WI SHOULD SEE MORE OF A RAIN/SNOW MIX IN THE AFTERNOON AS SFC TEMPS GET FAR ENUF ABOVE FREEZING. AS THE ENTIRE SYSTEM SHIFTS EAST SAT NGT...THE INVERTED TROF BECOMES MORE OF A CDFNT AND DRIVES EWD REACHING CNTRL WI BY 12Z SUNDAY. VARIETY OF PCPN WL CONT OVER NE WI WITH RAIN OVER E-CNTRL WI...RAIN BEGINNING TO MIX WITH SNOW LATE CNTRL/FAR NE WI AND A MIX CHANGING TO ALL SNOW IN N-CNTRL WI. UP TO A COUPLE INCHES OF WET SNOW CANNOT BE RULED OUT IN THE NORTH...OTHERWISE FOG MAY BECOME A BIGGER ISSUE DUE TO SNOWMELT AND LIGHT WINDS IN THE VICINITY OF THE CDFNT. THE CDFNT TO COMPLETE ITS PASSAGE THRU ERN WI SUNDAY MORNING...TO BE FOLLOWED BY THE PASSAGE OF THE SHORTWAVE TROF SUNDAY AFTERNOON. BETTER FORCING/LIFT TO ACCOMPANY THE CDFNT...THUS EXPECT HIGHER POPS WOULD BE NECESSARY DURING THE MORNING HOURS. DESPITE COOLER AIR CONTINUING TO FILTER INTO WI BEHIND THE FNT...THE MILD START TO THE DAY MAY STILL ALLOW FOR PCPN TO REMAIN ALL RAIN OVER E-CNTRL AND PARTS OF CNTRL WI SUNDAY AFTERNOON. THE NORTH SHOULD REMAIN ALL SNOW AND WOULD NOT BE SURPRISED TO SEE AN ADDITIONAL LIGHT ACCUMULATION OF SNOW. DO NOT ANTICIPATE MUCH OF A DIURNAL RISE IN TEMPS AS CAA TAKES OVER THRU THE DAY. PERHAPS A 3 TO 5 DEG RISE FROM MORNING LOWS IS ABOUT ALL WE WL ABLE TO MUSTER. IT NOW APPEARS THAT THE SRN STREAM WEAKENING UPR LOW/SFC WAVE ON THE OLD CDFNT WL PASS FAR ENUF TO OUR SE AS TO NOT HAVE ANY INFLUENCE ON OUR WEATHER. INSTEAD...A RDG OF HI PRES IS FCST TO BUILD INTO THE WRN GREAT LAKES SUNDAY NGT AND END THE GENERAL PCPN THREAT OVER NE WI. NORTH WINDS COULD BRING A FEW FLURRIES ACROSS THE MI BORDER SUNDAY NGT INTO MON...BUT EXPECT PARTLY CLOUDY SKIES TO PREVAIL WITH TEMPS TO BE SLIGHTLY BELOW NORMAL. MDLS CONT TO HAVE DIFFERENT IDEAS ON THE HANDLING OF A NRN STREAM CLIPPER-TYPE SYSTEM NEXT WEEK. THE ECWMF/ UKMET/GEM ARE FASTER/WEAKER WITH THE ASSOCIATED SFC LOW...WHILE THE GFS IS SLOWER/STRONGER. AT THIS POINT...EITHER SOLUTION COULD END UP BEING CORRECT...THUS HAVE TAKEN A DIPLOMATIC APPROACH (ESSENTIALLY SPLITTING THE DIFFERENCE) WHICH ENDED UP BRINGING A SMALL CHC OF SNOW INTO N-CNTRL WI MON NGT AND THEN A GENERAL CHC POP AREA-WIDE ON TUE. LINGERING ISOLATED SNOW SHWRS OR FLURRIES ARE POSSIBLE TUE NGT...BUT ANOTHER RDG OF HI PRES SHOULD BRING QUIET CONDITIONS ON WED. THE MAIN FCST PROBLEM FOR THE MIDDLE OF NEXT WEEK WL BE THE ORIENTATION OF THE MEAN FLOW AS THE ECMWF ADVERTISES A DEEPER ERN CONUS UPR TROF THAN THE GFS. THIS DIFFERENCE WL BE KEY TO THE TIMING OF THE NEXT PACIFIC SYSTEM WHICH WOULD ARRIVE WED NGT/THU (GFS) VERSUS THU NGT (ECWMF). GENERAL CONSENSUS WOULD FAVOR THE ECMWF...THUS HAVE LEANED TOWARD A DRY THU AS WELL. && .AVIATION...FOR 18Z TAF ISSUANCE ISSUED AT 1035 AM CST THU MAR 7 2013 CLOUDS HANGING TOUGH ACRS THE N. RAP RH PROGS SUGGEST THEY WL BE TOUGH TO DISLODGE...AND COULD OVERSPREAD MUCH OF THE REST OF THE AREA. BUT NOT READY TO GO ALONG WITH THAT AS MID-MARCH SUN SHOULD HELP MIXING NR THE EDGES OF THE CLD BAND. WL STAY THE COURSE AND HAVE A GRADUAL DECR IN CLDS ACRS THE N THIS AFTN. SOME MIDDLE AND HIGH CLDS STREAMING ACRS RM THE W SHOULD PREVENT WIDESPREAD DENSE FG OVERNIGHT. WL STICK WITH SOME OCNL MVFR CONDITIONS AS IN PREV TAFS. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS.......SKOWRONSKI SHORT TERM.....SKOWRONSKI LONG TERM......KALLAS AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1038 AM CST THU MAR 7 2013 UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE .SHORT TERM...TODAY THROUGH FRIDAY. CLOUDS AND TEMPERATURES CONTINUE TO BE THE ISSUE THIS PERIOD. UPPER RIDGE TO BUILD IN OVER THE STATE THROUGH FRIDAY WITH SURFACE RIDGE AXIS OVER CWA TONIGHT. STRUGGLING WITH TEMPERATURES EARLY THIS MORNING...AS LOW CLOUDS SLOW TO EXIT THE FOX VALLEY AND PARTS OF THE LAKESHORE. LAKE CLOUDS ALSO MOVING SOUTH INTO NORTHERN WI. OVERNIGHT TEMPERATURES SHOWING SIG VARIABILITY...BOUNCING AROUND AS CLOUDS MOVE IN AND OUT. TRENDS OFF SATELLITE... SUBSIDENCE/LOWERING INVERSION HEIGHTS AND DIMINISHING LLVL WINDS WOULD SUGGEST THE LOW CLOUDS WILL DIMINISH FAIRLY QUICKLY THIS MORNING...LEAVING ONLY PASSING MID/HIGH CLOUDS. COLD START THIS MORNING WOULD SUGGEST GOING BIT COOLER ON TODAYS HIGHS THAN PREVIOUS FORECAST. GUIDANCE ALSO POINTING COLDER...THOUGH WITH MARCH SUN AND PERSONAL BIAS TOWARDS BEING COLD ON THESE SHIFTS WILL NOT MAKE ANY SIG CHANGE. SURFACE RIDGE AXIS OVER STATE TONIGHT WITH LIGHT WINDS. ADDED PATCHY FOG TO FORECAST BASED ON UPSTREAM TRENDS. TEMP FALL TO BE LIMITED SOME BY MID/HIGH CLOUDS. WARMER ON FRI WITH SOUTHWEST FLOW ALOFT. 850 MB TEMPS FLOATING WITH ZERO BY END OF DAY. .LONG TERM...FRIDAY NIGHT THROUGH NEXT WEDNESDAY. THE MAIN FOCUS OF THIS PORTION OF THE FORECAST IS THE PRECIPITATION IMPACTS FROM A COLD FRONT PASSING ACROSS THE STATE SATURDAY INTO SUNDAY. MEDIUM RANGE MODELS TONIGHT HAVE TIMING DIFFERENCES WITH THE SW CONUS UPPER LOW AS IT TRACKS ACROSS THE CENTRAL PLAINS THIS WEEKEND TOWARDS THE GREAT LAKES. THE GFS AND GEM ARE NOTABLY ON THE FASTER SIDE OF THE SOLUTION ENVELOP STARTING BY 00Z SUNDAY COMPARED TO THE ECMWF AND NAM. THE LATTER MODELS HAVE MORE SUPPORT FROM THE GFS ENSEMBLE MEAN AND WILL STICK WITH THOSE MODELS...AS THEY ALSO HAVE SUPPORT FROM HPC. FRIDAY NIGHT THROUGH SATURDAY NIGHT...STRONG WARM ADVECTION WILL BE OCCURRING ACROSS THE GREAT PLAINS AND SOUTH-CENTRAL CANADA FRIDAY NIGHT AHEAD OF STRONG SHORTWAVES CONVERGING WITHIN THE NORTHERN AND SOUTHERN BRANCH OF THE JET STREAM. PRECIPITATION WILL BE SPREADING NORTHEAST ACROSS THE PLAINS...ON THE NOSE OF A 45-50 KT LLJ....AND SHOULD BE APPROACHING THE NORTHERN MISSISSIPPI VALLEY BY LATE FRIDAY NIGHT. BOTH THE NAM AND ECMWF SHOW DRY SE FLOW IN THE LOW LEVELS OCCURRING FRIDAY NIGHT...WHICH WILL HAVE TO BE OVERCOME FOR PRECIP TO REACH THE GROUND. THE PREVIOUS SHIFT INCREASED POPS TO MATCH OFFICES TO OUR WEST...BUT EVIDENCE IS NOT THERE TO INCREASE POPS FURTHER. THIS CHANGES INTO SATURDAY AS THE WARM ADVECTION SPREADS ACROSS THE WESTERN GREAT LAKES. THE NOSE OF THE 850MB THETAE AXIS POINTS TOWARDS CENTRAL MINNESOTA AND WESTERN WISCONSIN AND THIS IS WHERE THE HEAVIEST PRECIP SHOULD RESIDE. BUT ENOUGH MOISTURE SHIFTS INTO THE AREA THAT LIGHT PRECIP SHOULD ARRIVE INTO NORTH-CENTRAL WISCONSIN SATURDAY MORNING. PTYPE UPON ARRIVAL OF THE PRECIP REMAINS MESSY. THE SREF PORTRAYS A FAIRLY HIGH THREAT OF FREEZING RAIN OVER CENTRAL AND NORTH-CENTRAL WISCONSIN SATURDAY MORNING. BUT PROGGED SOUNDINGS INDICATE MAINLY A SNOW/SLEET THREAT AS PRECIP DYNAMICALLY COOLS THE COLUMN. ENOUGH WARM ADVECTION SHOULD OCCUR BY AFTERNOON THAT A MIXED PRECIP THREAT IS DIMINISHED AS SURFACE TEMPS RISE ABOVE FREEZING EVEN OVER NORTH-CENTRAL WISCONSIN. WILL BACK OFF PRECIP AMOUNTS ON SATURDAY...BUT NORTH-CENTRAL WISCONSIN COULD STILL SEE AN INCH OR TWO OF SNOW BY SATURDAY EVENING. MOST OF THE PRECIP SHOULD BE FALLING SATURDAY NIGHT AS THE COLD FRONT WORKS ACROSS THE STATE. INCREASING UPPER DIVERGENCE AND MID-LEVEL FGEN WILL SUPPORT A WIDESPREAD BAND OF PRECIP THAT SHOULD MOSTLY FALL AS RAIN EXCEPT OVER N-C WISCONSIN WHERE A RAIN/SNOW MIX WILL CHANGE OVER TO SNOW. WILL SLOW DOWN THE TRANSITION TO SNOW AS THE COLDER AIR LOOKS TO BE SLOWER ARRIVING BEHIND THE FRONT. THERE HAS BEEN SOME CONCERN ABOUT PRECIP AMOUNTS LEADING TO FLOODING. INITIAL GUESS POINTS TOWARDS A QUARTER TO A HALF INCH OF PRECIP WILL FALL. HEAVIER AMOUNTS MAY SPLIT THE REGION TO THE NORTH AND SOUTH...DIRECTLY AHEAD OF THE SHORTWAVES. UNLESS THERE IS MORE EVIDENCE THAT THE NOSE OF A LLJ WORKS INTO THE AREA...THINK FLOODING POTENTIAL IS MINOR. BELIEVE E-C WISCONSIN STANDS THE BEST CHANCE THOUGH...IF WERE FORCED TO PICK AN AREA THAT COULD SEE SOME FLOODING. WILL CONTINUE TO HIGHLIGHT THREAT IN THE HWO UNTIL EVIDENCE BECOMES MORE CLEAR. REST OF THE FORECAST...THE FRONT WILL FINISH CROSSING THE EASTERN PART OF THE FORECAST AREA ON SUNDAY AND LIGHT PRECIP WILL BE ONGOING SUNDAY MORNING. PTYPE WILL BE GRADUALLY CHANGING FROM RAIN TO SNOW OVER CENTRAL AND NORTHEAST WISCONSIN OVER THE COURSE OF THE DAY. ANY SNOW AMOUNTS WILL LIKELY BE UP TO AN INCH. PRECIP PUSHES TO THE SOUTHEAST SUNDAY NIGHT. HIGH PRESSURE WILL BUILD INTO THE AREA ON MONDAY...WHEN WE SHOULD HAVE A PERIOD OF CLEARING SKIES. BUT A CLIPPER SYSTEM WILL QUICKLY ARRIVE MONDAY NIGHT AND PASS OVER THE AREA ON TUESDAY...WHICH WILL RETURN SNOW CHANCES. COULD SEE AN INCH OR TWO OUT OF THIS CLIPPER. HIGH PRESSURE RETURNS ON WEDNESDAY. COULD SEE A BIG WARMUP AT THE END OF THE WEEK THOUGH. && .AVIATION...FOR 18Z TAF ISSUANCE ISSUED AT 1035 AM CST THU MAR 7 2013 CLOUDS HANGING TOUGH ACRS THE N. RAP RH PROGS SUGGEST THEY WL BE TOUGH TO DISLODGE...AND COULD OVERSPREAD MUCH OF THE REST OF THE AREA. BUT NOT READY TO GO ALONG WITH THAT AS MID-MARCH SUN SHOULD HELP MIXING NR THE EDGES OF THE CLD BAND. WL STAY THE COURSE AND HAVE A GRADUAL DECR IN CLDS ACRS THE N THIS AFTN. SOME MIDDLE AND HIGH CLDS STREAMING ACRS RM THE W SHOULD PREVENT WIDESPREAD DENSE FG OVERNIGHT. WL STICK WITH SOME OCNL MVFR CONDITIONS AS IN PREV TAFS. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....TE LONG TERM......MPC AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
346 AM CST THU MAR 7 2013 .SHORT TERM...TODAY THROUGH SATURDAY 346 AM CST THU MAR 7 2013 MAIN FORECAST CONCERNS ARE ON THE STORM SYSTEM EXPECTED TO IMPACT THE AREA FRIDAY NIGHT THROUGH SUNDAY. LATEST WATER VAPOR IMAGERY SHOWED A WEAK UPPER LOW OVER NORTHERN LAKE SUPERIOR MOVING SOUTHEAST. A BROAD UPPER TROUGH WAS MOVING INTO THE WEST COAST AS RIDGING WAS OCCURRING OVER THE CENTRAL CONUS. SURFACE OBSERVATIONS INDICATED HIGH PRESSURE OVER THE FORECAST AREA...WITH THE RIDGE AXIS EXTENDING FROM WESTERN ONTARIO SOUTH THROUGH THE MID MISSISSIPPI RIVER VALLEY. AFTER SOME PATCHY DENSE FOG THIS MORNING...HIGH PRESSURE WILL BE IN CONTROL ACROSS THE AREA TODAY PROVIDING QUIET WEATHER. PASSING HIGH CLOUDS...CIRRUS...ARE EXPECTED TO MOVE OVER THE AREA TODAY AS THEY SPILL OVER THE RIDGE AHEAD OF THE TROUGH DIVING INTO THE WESTERN U.S. PLAN ON MOSTLY SUNNY SKIES TODAY WITH HIGHS RANGING FROM THE LOWER TO MID 30S. THE HIGH WILL START TO SLIDE EAST TONIGHT. MEANWHILE THE WESTERN TROUGH IS EXPECTED TO DIG SOUTH THROUGH SOUTHERN CALIFORNIA. SURFACE LOW PRESSURE WILL DEVELOP IN THE LEE OF THE ROCKIES PRODUCING SOUTHERLY FLOW ACROSS THE PLAINS INTO THE UPPER MISSISSIPPI RIVER VALLEY. SLIGHTLY WARMER AIR WILL ADVECT NORTHWARD STARTING TONIGHT AND CONTINUING INTO FRIDAY. 925 MB TEMPERATURES START OUT AROUND -7C ACROSS MOST OF THE AREA TODAY...WARMING TO AROUND 1C OVER SOUTHEAST MINNESOTA AND TO AROUND -5 C OVER CENTRAL WISCONSIN OVERNIGHT. PLAN ON PARTLY CLOUDY SKIES TONIGHT WITH LOWS RANGING FORM THE LOWER 20S WEST OF THE MISSISSIPPI RIVER TO THE TEENS FOR LOCATIONS TO THE EAST. A WEAK SHORTWAVE LOOKS TO MOVE ACROSS NORTH DAKOTA AND INTO WESTERN ONTARIO ON FRIDAY...PASSING WELL TO THE NORTH OF THE FORECAST AREA. CLOUDS WILL BE ON THE INCREASE ACROSS THE UPPER MISSISSIPPI RIVER VALLEY ON ON FRIDAY AS THE WESTERN TROUGH MOVES THROUGH THE FOUR CORNERS REGION AND LOW PRESSURE DEEPENS OVER EASTERN COLORADO. FLOW ALOFT WILL TURN SOUTHWEST LATE IN THE DAY ON FRIDAY OVER THE FORECAST AREA. MEANWHILE...A NORTHERN STREAM TROUGH IS EXPECTED TO RACE ACROSS SOUTHERN ALBERTA/SASKATCHEWAN AND MERGE WITH THE ENERGY LIFTING OUT OF THE SOUTHWEST. AN INVERTED SURFACE TROUGH DEVELOPS ACROSS THE UPPER MIDWEST FRIDAY NIGHT EXTENDING FROM SOUTHWEST NEBRASKA NORTHEAST INTO NORTHWEST WISCONSIN. GULF MOISTURE SURGES NORTHWARD FRIDAY NIGHT INTO SATURDAY WITH DEWPOINTS CLIMBING INTO THE UPPER 40S TO LOWER 50S OVER THE CENTRAL PLAINS. A MOISTURE RICH AIRMASS STREAMS INTO THE FORECAST AREA FRIDAY NIGHT INTO SATURDAY MORNING WITH PRECIPITABLE WATER VALUES CLIMBING TO 8/10 OF AN INCH BY EARLY SATURDAY MORNING...THEN INCREASING THROUGH THE DAY TO AROUND 9/10 OF AN INCH BY SATURDAY EVENING...WHICH IS AROUND 270 PERCENT OF NORMAL. EXPECT A MIXTURE OF FREEZING RAIN AND SLEET FRIDAY NIGHT AS THIS AIRMASS MOVES. THE MIX SHOULD SWITCH OVER TO ALL RAIN BY MID SATURDAY MORNING. ICE ACCUMULATIONS OF 1/10 OF AN INCH ARE POSSIBLE FROM LATE FRIDAY NIGHT INTO EARLY SATURDAY MORNING. IN ADDITION...PATCHY FOG LOOKS TO DEVELOP WEST OF THE MISSISSIPPI RIVER FRIDAY NIGHT AN COULD BE LOCALLY DENSE AT TIMES. THE RAIN WILL CONTINUE THROUGH THE DAY ON SATURDAY. TEMPERATURES ARE EXPECTED TO WARM GRADUALLY WARM FROM LATE FRIDAY NIGHT INTO SATURDAY MORNING. HIGHS ON SATURDAY WILL RANGE FROM THE MID TO UPPER 30S OVER NORTH CENTRAL WISCONSIN TO THE LOWER 40S ACROSS PORTIONS OF NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN. RAINFALL AMOUNTS ON SATURDAY INTO SATURDAY NIGHT WILL RANGE FROM 1/2 INCH OVER NORTH CENTRAL WISCONSIN TO AROUND 8/10 OF AN INCH OVER PORTIONS OF NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN. CANNOT RULE OUT SOME 1 INCH REPORTS FOR A FEW AREAS SOUTH OF INTERSTATE 90 BY EARLY SUNDAY MORNING. SOME MELTING SNOW AND THE EXPECTED RAINFALL COULD LEAD TO RUNOFF INTO AREA RIVERS AND STREAMS RESULTING IN SOME RISES AND POSSIBLY ICE JAMS...SEE HYDROLOGY SECTION BELOW. THE SURFACE TROUGH SLIDES OVER THE FORECAST AREA SATURDAY NIGHT WITH WINDS BECOMING LIGHT. THESE LIGHT WINDS COUPLED WITH A MOIST AIRMASS OVER THE AREA AND MELTING SNOW WILL LEAD TO DENSE FOG CONCERNS. AREAS OF DENSE FOG COULD DEVELOP SATURDAY EVENING AND CONTINUE THROUGH THE OVERNIGHT HOURS. .LONG TERM...SUNDAY THROUGH WEDNESDAY 346 AM CST THU MAR 7 2013 07.00 MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT SUNDAY INTO MONDAY SHOWING THE UPPER TROUGH PROGRESSING EAST THROUGH THE FORECAST AREA ON SUNDAY AND INTO THE EASTER GREAT LAKES REGION SUNDAY NIGHT. RAIN SHOULD GRADUALLY SWITCH OVER TO SNOW FROM THE NORTHWEST TO SOUTHEAST ON SUNDAY AS THE TROUGH MOVES IN. THE PRECIPITATION WILL END BY SUNDAY EVENING AS HIGH PRESSURE BUILDS IN FROM THE NORTHERN PLAINS. TEMPERATURES WILL RETURN TO MORE SEASONABLE VALUES ON MONDAY WITH HIGHS IN THE UPPER 20S TO LOWER 30S. A FAST MOVING SHORTWAVE IS EXPECTED TO MOVE ACROSS NORTHERN MINNESOTA INTO NORTHERN WISCONSIN MONDAY NIGHT THROUGH TUESDAY BRINGING SNOW CHANCES TO FAR NORTH CENTRAL WISCONSIN. HIGH PRESSURE RETURNS BY MIDWEEK WITH QUIET WEATHER EXPECTED. HIGH TEMPERATURES TUESDAY THROUGH THURSDAY WILL RANGE FROM THE MID TO UPPER 30S. && .AVIATION...THROUGH 06Z FRIDAY 1120 PM CST WED MAR 6 2013 AS THE HIGH PRESSURE RIDGE CONTINUES TO BUILD INTO THE AREA THIS EVENING...THE CLOUDS OVER MINNESOTA HAVE CONTINUED TO RETREAT TO THE WEST. THESE ARE NOW MAINLY WEST OF A KMKT TO KAXA LINE AND THE 07.03Z RAP SUGGESTS THESE CLOUDS WILL NOW REMAIN WEST OF THE AREA. SOME PATCHY DENSE FOG HAS FORMED BUT IS VARIABLE ON HOW MUCH OF VISIBILITY RESTRICTION OCCURS. BOTH KTOB AND KAUM WERE DOWN TO 1/4SM AT 07.04Z BUT KAUM IMPROVED TO 1SM AT 07.05Z. KRST BOUNCED FROM 6SM DOWN TO 1SM BACK UP TO 4SM BETWEEN 07.04Z AND 07.05Z. WITH THE LIGHT WINDS AND CLEAR SKIES OVERHEAD...WOULD EXPECT THE FOG TO CONTINUE FORMING AND HAVE TAKEN KRST DOWN TO IFR CONDITIONS FOR THE OVERNIGHT HOURS. THE RAP IS NOT AS AGGRESSIVE WITH THE FOG AT KLSE WITH THE BUFKIT SOUNDING SUGGESTING SATURATION AT THE SURFACE WILL NOT OCCUR. CONFIDENCE IS NOT HIGH ON WHAT THE VISIBILITY WILL DO AT KLSE BUT FOR NOW HAVE STAYED WITH MVFR CONDITIONS. EXPECTING THE FOG TO DISSIPATE BY MID MORNING THURSDAY AS THE MIXING INCREASES ON THE BACK SIDE OF THE SURFACE HIGH WITH SOUTHEAST WINDS. ONCE THE FOG IS GONE...VFR CONDITIONS EXPECTED FOR THE REMAINDER OF THE PERIOD. && .HYDROLOGY... 346 AM CST THU MAR 7 2013 THE EXPECTED RAINFALL AND SNOWMELT FROM FRIDAY NIGHT THROUGH SATURDAY COULD RESULT IN RUNOFF INTO AREA RIVERS AND STREAMS...LEADING TO RISES AND POTENTIAL ICE JAMS. THE CURRENT SNOWPACK IN PLACE ACROSS THE AREA WILL ABSORB SOME OF THE RAINFALL. HOWEVER...THE BOTTOM LAYER OF THE SNOW PACK IS FAIRLY HARD/CRUSTED. MOST OF THE ABSORPTION SHOULD OCCUR IN THE TOP MOST RECENTLY FALLEN SNOW LAYER. THE TOP LAYER OF SOIL IS FROZEN SOLID WITH CONCRETE FROST SO WHAT THE SNOW DOES NOT ABSORB WILL GO DIRECTLY INTO RUNOFF. AT THIS TIME RAINFALL AMOUNTS OF 1/2 INCH TO AROUND 1 INCH ARE POSSIBLE. THE HIGHER AMOUNTS WOULD MOST LIKELY FALL ACROSS FAR NORTHEAST IOWA INTO SOUTHWEST WISCONSIN. WILL MAINTAIN A VERY CLOSE WATCH ON THIS SITUATION. && .ARX WATCHES/WARNINGS/ADVISORIES... 335 AM CST THU MAR 7 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...04 HYDROLOGY...DAS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1120 PM CST WED MAR 6 2013 .SHORT TERM...TONIGHT THROUGH SATURDAY 248 PM CST WED MAR 6 2013 FORECAST CONCERNS THROUGH THE SHORT TERM PERIOD INCLUDE FOG POTENTIAL TONIGHT AND THEN LIKELIHOOD OF PRECIPITATION FRIDAY NIGHT THROUGH SATURDAY. HAVE BEEN WATCHING SATELLITE CLOSELY TODAY REGARDING CLEARING TREND OF STRATOCUMULUS OR LACK THEREOF IN SOME CASES AS A RIDGE OF HIGH PRESSURE BUILDS EAST ACROSS MN/IA. FAIRLY LARGE HOLE IN THE CLOUDS NOW EXTENDING SOUTH WARD FROM WESTERN LAKE SUPERIOR THROUGH SOUTHEAST MN/WESTERN WI. THIS WAS DO TO SOME MIXING ALBEIT VERY LIGHT UNDER SUBSIDENT REGIME. FARTHER WEST UNDER THE RIDGE AXIS ITSELF ACROSS SOUTHWEST MN/CENTRAL IA...STRATOCUMULUS WAS THICKER WITH LACK OF MIXING. THIS COULD LEND TO A TRICKY CLOUD/FOG/TEMPERATURES FORECAST TONIGHT. MODEL-WISE...LOOKS LIKE REALLY NO MAJOR DIFFERENCES WERE NOTED WITH THE 12Z RUN. FOR TONIGHT...AS MENTIONED ABOVE...COULD BE A TRICKY FORECAST DEPENDING ON WHAT CLOUDS DO. WHERE THE CLOUDS STICK AROUND OUT WEST...TEMPERATURES SHOULD TREND WARMER. HOWEVER...WHERE CLEARING OCCURS ALONG AND EAST OF THE MISSISSIPPI RIVER...TEMPERATURES COULD REALLY TANK. THINKING FAVORED LOW-LYING BOG COUNTRY AND RELATIVELY FRESH SNOW PACK WILL LIKELY DRIVE LOWS TONIGHT INTO THE SINGLE DIGITS BELOW ZERO. MEANWHILE...WHERE CLOUDS LINGER...WILL LIKELY SEE LOWS IN THE TEENS. WILL ALSO HAVE TO WATCH FOG POTENTIAL TONIGHT GIVEN LOWER BOUNDARY LAYER MOISTURE LOADING FROM TODAY/S PARTIAL SNOWMELT WITH DEW POINTS IN THE UPPER TEENS AS OF 2 PM. HAVE MAINTAINED AREAS OF FOG FOR TONIGHT/EARLY THURSDAY MORNING...BUT NOT CONFIDENT HOW THICK IT WILL BECOME DUE TO THE CLOUD ISSUE UNDER THE RIDGE AXIS. PLAN ON WARMING FOR THURSDAY INTO FRIDAY AS SURFACE HIGH PRESSURE EXITS EAST OF THE AREA AND FLOW TURNS MORE SOUTHERLY. NAM HAS 925-850MB TEMPERATURES IN THE -5C TO 0C RANGE ON THURSDAY...AND -1C TO +3C ON FRIDAY. THIS SHOULD EQUATE TO HIGHS IN THE UPPER 20S TO LOWER 30S THURSDAY AND NEAR NORMAL LEVELS IN THE MIDDLE 30S TO AROUND 40 ON FRIDAY. FOR FRIDAY NIGHT INTO SATURDAY...A STRONG MID-LEVEL TROUGH COMBINED WITH CYCLOGENESIS ON THE LEESIDE OF THE COLORADO ROCKIES/HIGH PLAINS WILL TAP GULF MOISTURE NORTHWARD TOWARD THE AREA. NAM/GFS SHOWING NOSE OF INCREASING 925-850MB MOISTURE TRANSPORT GETTING INTO THE AREA BY FRIDAY EVENING WITH PRECIPITABLE WATER VALUES REACHING AROUND 0.75 INCH OR 200-250 PERCENT ABOVE NORMAL BY SATURDAY 12Z. NAM SOUNDINGS SHOW INITIALLY DRY LOWER LEVELS WITH COLUMN SATURATION OCCURRING AT OR ABOVE 700MB BEFORE MIDNIGHT...THEN TOTAL COLUMN SATURATION BY 12Z SATURDAY MORNING. AS SUCH...HELD PRECIPITATION TO CHANCE CATEGORY BEFORE MIDNIGHT FRIDAY...AND THEN LIKELY CATEGORY //WEST OF THE MISSISSIPPI RIVER//AFTER MIDNIGHT. NOW...AS FAR AS P-TYPE...THERMAL PROFILES SUPPORT A WINTRY MIX THROUGH FRIDAY NIGHT WITH FREEZING RAIN AND SLEET THE LIKELY OUTCOME. THROUGH THE DAY SATURDAY...WILL LIKELY SEE A TRANSITION FROM A WINTRY MIX TO ALL RAIN AS WARMING CONTINUES AHEAD OF THE MID-LEVEL TROUGH AND SURFACE LOW MOVING OUT OF THE PLAINS. GULF MOISTURE TAP CONTINUES INTO THE AREA WITH PRECIPITABLE WATER VALUES INCREASING INTO THE 0.75-1.00 INCH RANGE. MELTING SNOW AND RAINFALL INCREASES HYDROLOGY CONCERNS. HAVE INCLUDED A SEPARATE DISCUSSION SECTION BELOW TO SORT OUT THE DETAILS. MAY HAVE TO CONSIDER EVENTUAL HEADLINES FRIDAY NIGHT INTO SATURDAY MORNING FOR WINTRY MIX SCENARIO. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY 248 PM CST WED MAR 6 2013 06.12Z MEDIUM RANGE MODELS IN GOOD AGREEMENT. EXPECT A TRANSITION FROM RAIN TO SNOW AND PERHAPS SOME SLEET SATURDAY NIGHT AS A COLD FRONT DROPS THROUGH THE UPPER MISSISSIPPI RIVER VALLEY REGION. THEN FOR SUNDAY THROUGH MONDAY...A WAVE OF LOW PRESSURE RIPPLES NORTHEAST ALONG THIS FRONTAL BOUNDARY WITH DEFORMATION RAIN/SNOW EXTENDING NORTHWESTWARD INTO THE FORECAST AREA. WEATHER LOOKS FAIRLY QUIET MONDAY NIGHT THROUGH WEDNESDAY WITH WEST/NORTHWEST FLOW ACROSS THE AREA. WILL KEEP A EYE ON A WEAK MID-LEVEL TROUGH DROPPING INTO THE AREA MONDAY NIGHT/TUESDAY TIME FRAME FOR A CHANCE OF LIGHT SNOW MAINLY NORTH OF I-94. OTHERWISE...WITH WEST/NORTHWEST FLOW ALOFT...LOOK FOR NORMAL TO SLIGHTLY BELOW NORMAL TEMPERATURES THROUGH THE PERIOD WITH HIGHS MAINLY IN THE MIDDLE/UPPER 30S. && .AVIATION...THROUGH 06Z FRIDAY 1120 PM CST WED MAR 6 2013 AS THE HIGH PRESSURE RIDGE CONTINUES TO BUILD INTO THE AREA THIS EVENING...THE CLOUDS OVER MINNESOTA HAVE CONTINUED TO RETREAT TO THE WEST. THESE ARE NOW MAINLY WEST OF A KMKT TO KAXA LINE AND THE 07.03Z RAP SUGGESTS THESE CLOUDS WILL NOW REMAIN WEST OF THE AREA. SOME PATCHY DENSE FOG HAS FORMED BUT IS VARIABLE ON HOW MUCH OF VISIBILITY RESTRICTION OCCURS. BOTH KTOB AND KAUM WERE DOWN TO 1/4SM AT 07.04Z BUT KAUM IMPROVED TO 1SM AT 07.05Z. KRST BOUNCED FROM 6SM DOWN TO 1SM BACK UP TO 4SM BETWEEN 07.04Z AND 07.05Z. WITH THE LIGHT WINDS AND CLEAR SKIES OVERHEAD...WOULD EXPECT THE FOG TO CONTINUE FORMING AND HAVE TAKEN KRST DOWN TO IFR CONDITIONS FOR THE OVERNIGHT HOURS. THE RAP IS NOT AS AGGRESSIVE WITH THE FOG AT KLSE WITH THE BUFKIT SOUNDING SUGGESTING SATURATION AT THE SURFACE WILL NOT OCCUR. CONFIDENCE IS NOT HIGH ON WHAT THE VISIBILITY WILL DO AT KLSE BUT FOR NOW HAVE STAYED WITH MVFR CONDITIONS. EXPECTING THE FOG TO DISSIPATE BY MID MORNING THURSDAY AS THE MIXING INCREASES ON THE BACK SIDE OF THE SURFACE HIGH WITH SOUTHEAST WINDS. ONCE THE FOG IS GONE...VFR CONDITIONS EXPECTED FOR THE REMAINDER OF THE PERIOD. && .HYDROLOGY... 248 PM CST WED MAR 6 2013 CONCERN INCREASING SLIGHTLY WITH ANTICIPATED RAINFALL/SNOWMELT FRIDAY NIGHT THROUGH SATURDAY NIGHT. MODELS INDICATING A GOOD SLUG OF GULF MOISTURE ADVECTING NORTHWARD INTO THE UPPER MISSISSIPPI RIVER REGION. RIGHT NOW...EXPECTING RAINFALL//CENTERED ON SATURDAY// OF A 1/4 TO 1/2 INCH. THINKING THAT CURRENT SNOWPACK IN PLACE WOULD BE ABLE TO ABSORB MOST OF THIS RAINFALL AS SNOWPACK TEMPERATURES STILL IN THE TEENS ACROSS NORTH CENTRAL WISCONSIN...AND IN THE MIDDLE 20S ACROSS SOUTHERN WI/NORTHEAST IA. HOWEVER...IF WE DO END UP WITH MORE RAINFALL GIVEN FAIRLY HIGH PRECIPITABLE WATER VALUES IN THE COLUMN OF ATMOSPHERE...OR WARMER TEMPERATURES AND FURTHER RIPENING OF THE SNOWPACK...RUNOFF COULD BECOME A PROBLEM. FROST DEPTH IS QUITE DEEP /1.5 TO 3 FEET/ AND THE TOP SEVERAL INCHES ARE FROZEN SOLID WITH CONCRETE FROST. ANY SNOWMELT OR RAINFALL WILL ALL RUN OFF INTO WATERWAYS. THERE IS ALSO ICE IN SOME OF OUR CREEKS AND RIVERS...SO IF THERE IS A RISE...WE COULD ALSO SEE SOME ICE ACTION. AS SUCH...WE WILL CONTINUE TO KEEP A CLOSE EYE ON THIS SITUATION. && .ARX WATCHES/WARNINGS/ADVISORIES... 248 PM CST WED MAR 6 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...04 HYDROLOGY...DAS
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
321 AM CST SAT MAR 9 2013 .DISCUSSION... 924 PM CST NO REAL BIG CHANGES TO GOING FORECAST TONIGHT...WITH ONLY MINOR EDITS TO POP/WX FOR AREAS ACROSS NORTHWEST ILLINOIS. LATEST SATELLITE IMAGERY DEPICTING MID/UPPER LEVEL CLOUD COVER CONTINUING TO STREAM NORTHEAST ACROSS THE REGION THIS EVENING...AS SOUTHWESTERLY FLOW CONTINUES OUT AHEAD OF AN APPROACHING LONGWAVE TROUGH OVER THE WESTERN CONUS. THIS IS USHERING IN A WARMER AND MORE MOIST ENVIRONMENT WITH LATEST RAP ANALYSIS DEPICTING STRONG WAA OCCURRING ACROSS MUCH OF THE PLAINS...AND CAN BE NOTED VIA THE ABUNDANCE OF CLOUD COVER AS WELL AS THE WIDESPREAD PRECIP SHIELD IN THIS LOCATION. ALTHOUGH THE STRONGEST WAA WILL REMAIN JUST TO THE WEST OF THE CWA...LATEST SHORT TERM GUIDANCE IS INDICATING THAT SOME LIGHT PRECIP DEVELOPMENT COULD OCCUR ACROSS NORTHWEST ILLINOIS TONIGHT AS THIS WAA WING CONTINUES TO LIFT NORTH/NORTHEAST. PRECIP DEVELOPMENT LATE TONIGHT ACROSS AREAS ALONG AND WEST OF INTERSTATE 39 DOES SEEM REASONABLE WITH THIS BETTER FORCING ALREADY INCHING CLOSER TO THE CWA. ALTHOUGH THIS FORCING WILL REMAIN RATHER WEAK...IT MAY BE ENOUGH OF A PERSISTENT FEATURE TO OVERCOME SOME DRIER AIR IN PLACE. THERMAL PROFILES WILL SUPPORT PRECIP OF THE LIQUID TYPE...BUT WITH THE POSSIBILITY OF A BRIEF WINDOW OF LIGHT FREEZING RAIN. ALTHOUGH...WARMING TONIGHT SHOULD MITIGATE ANY OVERALL FREEZING RAIN POTENTIAL WITH SURFACE TEMPERATURES EXPECTED TO BE HOVERING AROUND FREEZING IF NOT BEGINNING TO RISE JUST ABOVE BY THE TIME THIS PRECIP ARRIVES. SO HAVE MADE MENTION OF A SLIGHT CHANCE OF LIGHT RAIN/LIGHT FREEZING RAIN FOR LATE TONIGHT INTO EARLY SATURDAY MORNING BEFORE TEMPERATURES CONTINUE TO RISE THROUGH MID SATURDAY MORNING WITH ONLY RAIN THEN EXPECTED. RODRIGUEZ //PREV DISCUSSION... 234 PM CST THE AREA WILL QUICKLY SHIFT FROM WINTER TO SPRING WEATHER THIS WEEKEND WITH EXPECTED RAINFALL/SNOW MELT WITH WARMING TEMPERATURES POSING A FLOOD THREAT...WITH THUNDERSTORMS NOT OUT OF THE QUESTION BY SUNDAY. UPS AND DOWNS IN TEMPERATURES ARE EXPECTED NEXT WEEK WITH A SERIES OF WEAKER SYSTEMS BRINGING PERIODIC LOW CHANCES FOR PRECIPITATION. SYNOPSIS...EARLY AFTERNOON WATER VAPOR IMAGERY SHOWS UPPER RIDGING BUILDING ACROSS THE MISSISSIPPI RIVER VALLEY INTO THE LOCAL AREA IN RESPONSE TO A DEEP CLOSED UPPER LOW ROTATING INTO THE DESERT SOUTHWEST. THIS TROUGH IS SPLIT FROM A TROUGH THAT IS POSITIONED OVER CENTRAL CANADA WITH A TROUGH AXIS SHIFTING TOWARDS WESTERN SASKATCHEWAN. THESE TWO FEATURES WILL BE THE MAIN DRIVERS OF EXPECTED RAINFALL THIS WEEKEND. AT THE SURFACE...A LARGE AREA OF HIGH PRESSURE IS EXITING THE LOCAL AREA TO THE EAST. WEAK LOW PRESSURE IS OVER SOUTHERN MANITOBA AND IS DRIFTING EASTWARD. TONIGHT AND SATURDAY...QUIET WEATHER WILL CONTINUE TONIGHT WITH THE UPPER RIDGE CRESTING THE AREA THIS EVENING. THE BIG SOUTHWEST TROUGH WILL BE MOVING EASTWARD WITH HEIGHT FALLS AHEAD OF IT AND BEHIND THE RIDGE ALLOWING LOW PRESSURE TO DEVELOP IN THE LEE OF THE ROCKIES. A 50+KT LOW LEVEL JET WILL SET UP ACROSS THE PLAINS RESULTING IN A STRONG PUSH OF HIGH THETA-E LOW LEVEL AIR ACROSS THE SOUTHERN AND CENTRAL PLAINS. HIGH LEVEL MOISTURE WILL BE SPREAD NORTHEASTWARD SUPPORTING AN INCREASE IN MID AND HIGH LEVEL CLOUD COVER OVERNIGHT. THE PRESSURE GRADIENT WILL BE WEAK ACROSS THE AREA EARLY BUT WILL TIGHTEN OVERNIGHT SO WINDS MAY DROP OFF FOR A TIME EARLY BEFORE INCREASING SOMEWHAT OVERNIGHT. LOW TEMPS WILL BE THE MAIN CHALLENGE AND MAY OCCUR DURING THE EVENING BUT SOME WARMING MAY OCCUR LATE AS CLOUDS AND WINDS INCREASE AND WARM ADVECTION IS UNDERWAY ALOFT. WILL GO AHEAD AND SHOW A STEADY OR WARMING TREND OVERNIGHT. LIGHT PRECIP BECOMES A CONCERN BY SATURDAY MORNING AS WAVES OF WARM ADVECTION BECOME MORE FOCUSED AND MOISTURE DEEPENS. THIS IS WHERE TEMPS WILL BECOME CRITICAL BECAUSE CHANCES FOR LIGHT PRECIP MAY BEGIN EARLY ENOUGH TO FALL AS FREEZING RAIN. SIGNALS FOR PRECIP ARE NOT ALL THAT ORGANIZED UNTIL SATURDAY AFTERNOON BUT WESTERN AREAS MAY HAVE DEEP ENOUGH MOISTURE AND ENOUGH WARM ASCENT OCCURRING ALOFT TO SEE LIGHT RAIN...OR FREEZING RAIN IF TEMPS START OUT BELOW FREEZING...BY LATE SATURDAY MORNING. ANY FREEZING PRECIP WILL QUICKLY END AS TEMPS WARM WELL ABOVE FREEZING BY EARLY AFTERNOON. PRECIP CHANCES WILL THEN EXPAND EASTWARD...ESPECIALLY ACROSS THE NORTHERN CWA SATURDAY AFTERNOON BUT CHANCES STILL LOOK RATHER LOW BUT STILL WORTH A MENTION GIVEN STEADILY INCREASING DEEP LAYER MOISTURE /PRECIPITABLE WATER VALUES REACH 0.75 INCHES OR SO BY LATE DAY/ AND WARM ADVECTION. SOUTH TO SOUTHEAST WINDS WILL BECOME BREEZY WHICH WILL HELP HIGHS WARM INTO LOW TO MID 40S NORTH AND MID TO UPPER 40S SOUTH. IT IS ALSO IMPORTANT TO NOTE THAT DEW POINTS WILL BE ON THE RISE AS WELL WHICH WILL COMBINE WITH THE STEADY WINDS AND MILD TEMPS TO PROVIDE INCREASINGLY EFFICIENT SNOW MELT THROUGH THE AFTERNOON. MORE ON THIS BELOW... SATURDAY NIGHT AND SUNDAY...THE SOUTHWEST UPPER LOW WILL BE LIFTING ACROSS THE SOUTHERN HIGH PLAINS AND PHASING WITH THE CENTRAL CANADA UPPER TROUGH WHICH WILL BE SHARPENING AS IT PIVOTS SOUTHEASTWARD. THE MAIN SURFACE LOW IS EXPECTED TO ORGANIZE IN VICINITY OF THE SOUTHERN UPPER LOW ACROSS WESTERN KANSAS BY SATURDAY EVENING WITH AN INVERTED TROUGH EXTENDING NORTHWARD INTO WESTERN ONTARIO. GULF MOISTURE WILL CONTINUE TO STREAM NORTHWARD AHEAD OF THE LOW AS 60KT LOW LEVEL JET SPREADS ACROSS MISSOURI...ILLINOIS...AND LAKE MICHIGAN LATER SATURDAY EVENING. PRECIPITABLE WATER VALUES WILL FURTHER SURGE REACHING THE 1 TO PERHAPS 1.25 INCH RANGE WHICH WILL COMBINE WITH INCREASED ASCENT TO PRODUCE WIDESPREAD RAIN ACROSS THE MID-MISSISSIPPI RIVER VALLEY WHICH WILL THEN SPREAD EASTWARD DURING THE EVENING AND OVERNIGHT HOURS. THE UPPER LOW WILL BE TO THE WEST OF THE AREA BY SUNDAY MORNING WHICH WILL LIKELY BRING A DRY SLOT INTO THE AREA SOMETIME SUNDAY MORNING. INSTABILITY DOES INCREASE AS WELL...POTENTIALLY WITH ENOUGH ELEVATED INSTABILITY TO SUPPORT SOME THUNDER POTENTIAL ON THE LEADING EDGE OF THE DRY SLOT. FURTHERMORE...SOME MINIMAL SURFACE INSTABILITY COULD DEVELOP AS WELL WHICH WOULD POSE AN ADDITIONAL THUNDER THREAT...ESPECIALLY ALONG THE APPROACHING COLD FRONT WHICH WILL CROSS THE AREA LATER IN THE DAY. HOWEVER...THE DEEPER DRY AIR OF THE DRY SLOT MAY PRECLUDE MUCH IF ANY DEVELOPMENT ALONG THE FRONT IF SURFACE BASED INSTABILITY DOES IN FACT DEVELOP. STILL TOO EARLY TO HAVE ANY HIGH DEGREE OF CONFIDENCE IN THUNDER POTENTIAL BUT FEEL THIS BEARS WATCHING GIVEN THE HIGH DEGREE OF DEEP LAYER WIND SHEAR AND FAIRLY STRONG LOW LEVEL WIND FIELD. HIGH TEMPS SUNDAY LOOK TO RANGE FROM THE MID 40S NORTHWEST TO THE MID 50S SOUTHEAST. PRECIP AMOUNTS/FLOODING POTENTIAL...FORECAST GUIDANCE IS IN PRETTY GOOD AGREEMENT WITH THE TRACK OF LOW LEVEL FEATURES BUT DO DIFFER IN THE PLACEMENT OF OTHER FEATURES SUCH AS THE PATH OF THE UPPER JET CORE. QPF OUTPUT DOES DIFFER SOMEWHAT AS A RESULT...ESPECIALLY IN PLACEMENT OF HEAVIEST VALUES. ARRIVAL TIMING MAY ALSO NEED ADJUSTMENT WITH SOME GUIDANCE BEING SLOWER BUT RIGHT NOW THE DIFFERENCES ARE ON THE ORDER OF A FEW HOURS. THE WESTERN AND NORTHERN CWA CONTINUES TO LOOK TO HAVE THE BEST CHANCE AT RECEIVING PEAK RAINFALL AMOUNTS...OR ROUGHLY FROM CHICAGO TO PONTIAC AND POINTS WEST BUT THE ENTIRE CWA DOES LOOK TO SEE RAINFALL. GIVEN THE PRECIPITABLE WATER VALUES AND DURATION OF FORCING...AMOUNTS OF 0.75-1.00 INCHES ARE PLAUSIBLE IN THE NORTH AND WEST WITH LESSER AMOUNTS SOUTHEAST. IF CONVECTION CAN DEVELOP SUNDAY MORNING THEN AMOUNTS WOULD BE HIGHER IN SPOTS BUT IT IS POSSIBLE THAT THE BEST CHANCE FOR CONVECTION COULD END UP BEING ACROSS THE SOUTHERN/EASTERN CWA GIVEN THE LIKELY TRACK OF THE DRY SLOT AND ARRIVAL OF INSTABILITY. SO CONFIDENCE IN SPECIFIC AMOUNTS AND WHERE THEY OCCUR IS STILL LIMITED. HOWEVER...EVEN SOMEWHAT LOWER AMOUNTS THAN THOSE ABOVE ARE STILL A CONCERN GIVEN THE AMOUNT OF WATER IN THE CURRENT SNOW PACK. REFERENCE HYDROLOGY SECTION BELOW AND ESFLOT PRODUCT FOR MORE DETAILS. SUNDAY NIGHT AND MONDAY...TIMING DIFFERENCES BECOME MORE CRITICAL AS THE SYSTEM DEPARTS SUNDAY NIGHT AND MONDAY. IN TERMS OF FRONTAL TIMING...THERE IS GOOD AGREEMENT ON HAVING THE COLD FRONT SWEEP ACROSS THE AREA SUNDAY AFTERNOON WHICH ALLOWS COLDER AIR TO ARRIVE...BUT THE SPEED WITH WHICH IT ARRIVES IS NOT QUITE CLEAR. THE ECMWF/GEM REMAIN SLOWER WITH THE PASSAGE OF THE UPPER TROUGH AXIS DELAYING THE ARRIVAL OF COLDEST AIR...AS WELL AS THE ATTENDANT DEFORMATION FORCING HOLDING IT OFF UNTIL CLOSER TO MONDAY MORNING. THE NAM AND GFS ARE FASTER WITH THE UPPER TROUGH AND ARRIVAL OF COLD AIR. THIS WILL PLAY HAVOC WITH PRECIP TIMING AND TYPE BEHIND THE FRONT INTO MONDAY MORNING. WILL NEED TO MONITOR THIS PERIOD AS THERE IS AT LEAST SOME SUPPORT FOR MEASURABLE PRECIP MONDAY. MDB LONG TERM...MONDAY NIGHT THROUGH FRIDAY... THE EXTENDED PERIOD WILL FEATURE A FAIRLY PROGRESSIVE NORTHWEST TO PERHAPS ZONAL FLOW WITH SEVERAL WEAK SYSTEMS TO AFFECT PART OF THE REGION/GREAT LAKES. TIMING ANY OF THESE FEATURES IS SOMEWHAT DIFFICULT AS THEIR STRENGTH/LOCATION CONTINUES TO FLUCTUATE FROM RUN TO RUN AS WELL AS FROM MODEL TO MODEL. WHILE THERE WILL BE A FEW CHANCES FOR PRECIP...WILL CONTINUE WITH MAINLY A DRY FORECAST DUE TO LOW CONFIDENCE THOUGH HAVE INCLUDED A SLIGHT CHANCE OF SHOWERS ON FRIDAY AS THERE HAS BEEN SOME CONTINUITY DURING THIS TIME PERIOD. SHOULD PRECIP CHANCES/TRENDS INCREASE...PRECIP TYPE WILL BECOME A CONCERN DEPENDING ON TIME OF DAY. TEMPERATURES ARE EQUALLY CHALLENGING...DEPENDING ON THE TIMING OF THESE FEATURES AND THE EXTENT OF COLD AIR THEY BRING WITH THEM. ECMWF HAD BEEN FAIRLY CONSISTENT WITH A PUSH OF COLDER AIR THURSDAY INTO FRIDAY WHICH IS NOW GONE WHILE THE GFS IS NOW MUCH COLDER. HAVE TRENDED MIDDLE OF THE ROAD WITH TEMPS AND GIVEN MID MARCH SUNSHINE... LACK OF ANY SIGNIFICANT COLD AIR PUSH WOULD SUPPORT TEMPS NEAR SEASONAL NORMALS. CMS && .HYDROLOGY... 234 PM CST SOME AREAS OF THE FORECAST AREA MAY SEE 0.75-1.00 INCHES OF RAINFALL FROM SATURDAY THROUGH SUNDAY...WITH THE BULK EXPECTED SATURDAY EVENING/NIGHT. AT THIS POINT...THESE RAINFALL AMOUNTS ARE EXPECTED GENERALLY WEST OF A LINE FROM CHICAGO TO PONTIAC WITH LESSER AMOUNTS SOUTHEAST BUT THERE IS SOME OPPORTUNITY FOR THE LOCATION TO NEED ADJUSTMENT. IN ADDITION...SOME CONVECTIVE RAINFALL IS POSSIBLE WHICH COULD RESULT IN LOCALLY HIGHER AMOUNTS. OBSERVED SNOW CORE WATER EQUIVALENTS RANGE FROM AROUND AN INCH TO AROUND 2.5 INCHES WHERE THE DEEPEST SNOW EXISTS...MAINLY NORTH OF INTERSTATE 80. FROST DEPTH REMAINS IN THE 6 TO 10 INCH RANGE. THE EXPECTATION IS THAT THE SNOW WILL MELT AND RUNOFF WILL BE REALIZED BEFORE THE FROST MELTS SIGNIFICANTLY DUE TO THE INSULATING EFFECTS OF THE SNOW PACK. SNOW MELT WILL COMMENCE BEFORE THE BULK OF THE RAINFALL WHICH COULD ALLOW SOME OF THE RUNOFF INTO AREA RIVERS AND STREAMS TO MAKE PROGRESS DOWNSTREAM BUT THIS WOULD LIKELY BE MINIMAL. MOST MELT WILL LIKELY OCCUR WITH THE RAINFALL SO RIVER RISES WILL OCCUR AND SOME RIVERS COULD EXCEED FLOOD STAGE LATER SUNDAY/MONDAY. AREAL OVERLAND FLOODING IS A POSSIBILITY...MAINLY IN LOW LYING AND POORLY DRAINED AREAS. REFERENCE ESFLOT FOR ADDITIONAL INFORMATION. && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * CHANCE OF SOME LIGHT RAIN THIS AFTERNOON. * RAIN AND FOG TIMING TONIGHT. * MVFR CIGS AND VISIBILITY LIKELY AFTER 06 UTC SATURDAY NIGHT. * IFR CIGS AND VISIBILITY POSSIBLE BY DAYBREAK ON SUNDAY MORNING. * LLWS POSSIBLE SATURDAY NIGHT. KJB //DISCUSSION...UPDATED 06Z... THE MAIN CONCERNS DURING THE PERIOD WILL BE WITH OUR NEXT STORM SYSTEM...WHICH IS CURRENTLY TAKING SHAPE ACROSS THE FRONT RANGE OF THE COLORADO ROCKIES. THIS SYSTEM IS ALREADY TRANSPORTING WARM AND MOIST AIR NORTHWARD ACROSS THE PLAINS AND INTO THE MID MISSOURI VALLEY WITH SCATTERED SHOWERS AND EVEN SOME THUNDERSTORMS ONGOING ACROSS THIS REGION. IT APPEARS SOME OF THESE SHOWERS MAY EFFECT KRFD AROUND DAYBREAK...AND WITH TEMPERATURES POSSIBLY NEAR FREEZING...I OPTED TO LEAVE THE -FZRA IN THE NEW TAF FROM 12-14 UTC THIS MORNING. HOWEVER...I HAVE LOW CONFIDENCE IN THE FREEZING THREAT AS TEMPERATURES MAY ACTUALLY JUMP ABOVE FREEZING PRIOR TO THE ONSET OF THE PRECIPITATION. IN ADDITION...I AM NOT SURE HOW MUCH IF ANY PRECIP WILL ACTUALLY FALL THIS MORNING. THERE IS STILL SOME DRY AIR IN THE LOW LEVELS TO OVERCOME...AND IT APPEARS THAT CIGS WILL STILL BE AT OR ABOVE 9000 FEET THROUGH 15 UTC. WITH THIS IN MIND...WE MAY NOT SEE MORE THAN A FEW SPRINKLES DURING THE EARLY MORNING HOURS AT KRFD. IT APPEARS MOST OF THE DAY PRIOR TO 20 UTC WILL BE DRY. AFTER 20 UTC WE COULD GET ANOTHER BATCH OF LIGHT RAIN ACROSS THE TAF SITES. THIS ALSO APPEARS AS THOUGH IT WILL BE RATHER LIGHT...AND I HAVE OPTED TO KEEP THE PROB 30 GROUP GOING FOR THIS ACTIVITY. I DID...HOWEVER...TRIM THE END TIME OF THE PROB 30 GROUP TO 01 UTC AS IT APPEARS THERE WILL BE QUITE A BIT OF DRY TIME THIS EVENING AHEAD OF THE MAIN BATCH OF RAIN. RAIN SHOULD ONSET AROUND OR SHORTLY AFTER 03 UTC THIS EVENING AT KRFD AND AFTER 06 UTC AT THE EASTERN TERMINALS AS THE MAIN STORM SYSTEM APPROACHES THE AREA. IT APPEARS THE RAIN WILL BE MODERATE AT TIMES WITH CIGS GRADUALLY LOWERING INTO THE IFR CATEGORY BY EARLY SUNDAY. VISIBILITIES WILL ALSO BE DEGRADING INTO AT LEAST THE MVFR RANGE IN RAIN AND FOG. LOW CLOUDS AND FOG LOOK TO CONTINUE INTO THE DAY ON SUNDAY AS THE SURFACE LOW MOVES OVERHEAD AND SURFACE DEW POINTS PEAK IN THE LOWER TO MIDDLE 40S. THERE IS ALSO A CHANCE OF LLWS SATURDAY NIGHT AS IT APPEARS THE A SOUTHWESTERLY 50-55 LOW LEVEL JET WILL DEVELOP AROUND 2,000 FT AGL. SURFACE WINDS DURING THIS TIME ARE EXPECTED TO BE AROUND 10 KT OUT OF THE SOUTH. I HAVE OPTED NOT TO ADD THIS TO THE NEW TAF...BUT IT MAY NEED TO BE ADDED AT A LATER TIME IF THESE CONDITIONS APPEAR TO BE SETTING UP. KJB //ORD AND MDW CONFIDENCE...UPDATED 09Z... * LOW CONFIDENCE ON ANY LIGHT RAIN AFFECTING THE TERMINALS THIS AFTERNOON. * MEDIUM TO HIGH CONFIDENCE IN RAIN AND FOG REDUCING VISIBILITIES UNDER 4 MILES LATER SUNDAY NIGHT AFTER 06 UTC. * MEDIUM CONFIDENCE IN IFR CIGS TOWARDS DAYBREAK SUNDAY. * LOW TO MEDIUM CONFIDENCE IN LLWS SATURDAY NIGHT. KJB //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY...RAIN AND FOG WITH LIKELY IFR. A CHANCE FOR A MIX WITH SNOW DURING THE NIGHT. MONDAY...SLIGHT CHANCE OF RAIN AND SNOW WITH MVFR. TUESDAY-THURSDAY...VFR. MTF && .MARINE... 228 AM CST A STORM SYSTEM...CURRENTLY TAKING SHAPE ACROSS THE FRONT RANGE OF THE COLORADO ROCKIES...WILL SPLIT OFF INTO TWO SYSTEMS. ONE WILL RACE NORTHEASTWARD ACROSS ONTARIO BY SUNDAY...WHILE THE SECOND SYSTEM MOVES TOWARDS THE SOUTHERN END OF LAKE MICHIGAN BY SUNDAY EVENING. THIS SECOND SYSTEM LOOKS TO HAVE A LARGE IMPACT ON THE WINDS OVER THE LAKE THROUGH THE WEEKEND. SOUTHERLY WINDS WILL OCCUR TODAY AND TONIGHT...UP AROUND 25 KT AHEAD OF THIS SYSTEM. THEN AS THE SURFACE LOW APPROACHES THE LAKE ON SUNDAY...THE WINDS WILL BECOME NORTH-NORTHEASTERLY AND INCREASE UP AROUND 30 KT...ESPECIALLY ACROSS THE NORTHERN END OF THE LAKE. GALE FORCE WINDS ARE QUITE POSSIBLE WITH THIS SYSTEM...BUT UNCERTAINTIES REMAIN AS TO THE EXACT TRACK OF THIS SYSTEM...AND HENCE WHERE THE STRONGEST WINDS WILL BE. ONCE THIS LOW PASSES OVER THE LAKE...A PERIOD OF NORTHWESTERLY WINDS OF 25 TO 30 KT LOOKS LIKELY INTO AT LEAST MONDAY. HOWEVER...THESE NORTHWESTERLY WINDS COULD CONTINUE INTO MIDWEEK AS IT APPEARS A WEAK CLIPPER SYSTEM MAY MOVE ACROSS THE LAKE SOMETIME ON TUESDAY OR TUESDAY EVENING. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
229 AM CST SAT MAR 9 2013 .DISCUSSION... 924 PM CST NO REAL BIG CHANGES TO GOING FORECAST TONIGHT...WITH ONLY MINOR EDITS TO POP/WX FOR AREAS ACROSS NORTHWEST ILLINOIS. LATEST SATELLITE IMAGERY DEPICTING MID/UPPER LEVEL CLOUD COVER CONTINUING TO STREAM NORTHEAST ACROSS THE REGION THIS EVENING...AS SOUTHWESTERLY FLOW CONTINUES OUT AHEAD OF AN APPROACHING LONGWAVE TROUGH OVER THE WESTERN CONUS. THIS IS USHERING IN A WARMER AND MORE MOIST ENVIRONMENT WITH LATEST RAP ANALYSIS DEPICTING STRONG WAA OCCURRING ACROSS MUCH OF THE PLAINS...AND CAN BE NOTED VIA THE ABUNDANCE OF CLOUD COVER AS WELL AS THE WIDESPREAD PRECIP SHIELD IN THIS LOCATION. ALTHOUGH THE STRONGEST WAA WILL REMAIN JUST TO THE WEST OF THE CWA...LATEST SHORT TERM GUIDANCE IS INDICATING THAT SOME LIGHT PRECIP DEVELOPMENT COULD OCCUR ACROSS NORTHWEST ILLINOIS TONIGHT AS THIS WAA WING CONTINUES TO LIFT NORTH/NORTHEAST. PRECIP DEVELOPMENT LATE TONIGHT ACROSS AREAS ALONG AND WEST OF INTERSTATE 39 DOES SEEM REASONABLE WITH THIS BETTER FORCING ALREADY INCHING CLOSER TO THE CWA. ALTHOUGH THIS FORCING WILL REMAIN RATHER WEAK...IT MAY BE ENOUGH OF A PERSISTENT FEATURE TO OVERCOME SOME DRIER AIR IN PLACE. THERMAL PROFILES WILL SUPPORT PRECIP OF THE LIQUID TYPE...BUT WITH THE POSSIBILITY OF A BRIEF WINDOW OF LIGHT FREEZING RAIN. ALTHOUGH...WARMING TONIGHT SHOULD MITIGATE ANY OVERALL FREEZING RAIN POTENTIAL WITH SURFACE TEMPERATURES EXPECTED TO BE HOVERING AROUND FREEZING IF NOT BEGINNING TO RISE JUST ABOVE BY THE TIME THIS PRECIP ARRIVES. SO HAVE MADE MENTION OF A SLIGHT CHANCE OF LIGHT RAIN/LIGHT FREEZING RAIN FOR LATE TONIGHT INTO EARLY SATURDAY MORNING BEFORE TEMPERATURES CONTINUE TO RISE THROUGH MID SATURDAY MORNING WITH ONLY RAIN THEN EXPECTED. RODRIGUEZ //PREV DISCUSSION... 234 PM CST THE AREA WILL QUICKLY SHIFT FROM WINTER TO SPRING WEATHER THIS WEEKEND WITH EXPECTED RAINFALL/SNOW MELT WITH WARMING TEMPERATURES POSING A FLOOD THREAT...WITH THUNDERSTORMS NOT OUT OF THE QUESTION BY SUNDAY. UPS AND DOWNS IN TEMPERATURES ARE EXPECTED NEXT WEEK WITH A SERIES OF WEAKER SYSTEMS BRINGING PERIODIC LOW CHANCES FOR PRECIPITATION. SYNOPSIS...EARLY AFTERNOON WATER VAPOR IMAGERY SHOWS UPPER RIDGING BUILDING ACROSS THE MISSISSIPPI RIVER VALLEY INTO THE LOCAL AREA IN RESPONSE TO A DEEP CLOSED UPPER LOW ROTATING INTO THE DESERT SOUTHWEST. THIS TROUGH IS SPLIT FROM A TROUGH THAT IS POSITIONED OVER CENTRAL CANADA WITH A TROUGH AXIS SHIFTING TOWARDS WESTERN SASKATCHEWAN. THESE TWO FEATURES WILL BE THE MAIN DRIVERS OF EXPECTED RAINFALL THIS WEEKEND. AT THE SURFACE...A LARGE AREA OF HIGH PRESSURE IS EXITING THE LOCAL AREA TO THE EAST. WEAK LOW PRESSURE IS OVER SOUTHERN MANITOBA AND IS DRIFTING EASTWARD. TONIGHT AND SATURDAY...QUIET WEATHER WILL CONTINUE TONIGHT WITH THE UPPER RIDGE CRESTING THE AREA THIS EVENING. THE BIG SOUTHWEST TROUGH WILL BE MOVING EASTWARD WITH HEIGHT FALLS AHEAD OF IT AND BEHIND THE RIDGE ALLOWING LOW PRESSURE TO DEVELOP IN THE LEE OF THE ROCKIES. A 50+KT LOW LEVEL JET WILL SET UP ACROSS THE PLAINS RESULTING IN A STRONG PUSH OF HIGH THETA-E LOW LEVEL AIR ACROSS THE SOUTHERN AND CENTRAL PLAINS. HIGH LEVEL MOISTURE WILL BE SPREAD NORTHEASTWARD SUPPORTING AN INCREASE IN MID AND HIGH LEVEL CLOUD COVER OVERNIGHT. THE PRESSURE GRADIENT WILL BE WEAK ACROSS THE AREA EARLY BUT WILL TIGHTEN OVERNIGHT SO WINDS MAY DROP OFF FOR A TIME EARLY BEFORE INCREASING SOMEWHAT OVERNIGHT. LOW TEMPS WILL BE THE MAIN CHALLENGE AND MAY OCCUR DURING THE EVENING BUT SOME WARMING MAY OCCUR LATE AS CLOUDS AND WINDS INCREASE AND WARM ADVECTION IS UNDERWAY ALOFT. WILL GO AHEAD AND SHOW A STEADY OR WARMING TREND OVERNIGHT. LIGHT PRECIP BECOMES A CONCERN BY SATURDAY MORNING AS WAVES OF WARM ADVECTION BECOME MORE FOCUSED AND MOISTURE DEEPENS. THIS IS WHERE TEMPS WILL BECOME CRITICAL BECAUSE CHANCES FOR LIGHT PRECIP MAY BEGIN EARLY ENOUGH TO FALL AS FREEZING RAIN. SIGNALS FOR PRECIP ARE NOT ALL THAT ORGANIZED UNTIL SATURDAY AFTERNOON BUT WESTERN AREAS MAY HAVE DEEP ENOUGH MOISTURE AND ENOUGH WARM ASCENT OCCURRING ALOFT TO SEE LIGHT RAIN...OR FREEZING RAIN IF TEMPS START OUT BELOW FREEZING...BY LATE SATURDAY MORNING. ANY FREEZING PRECIP WILL QUICKLY END AS TEMPS WARM WELL ABOVE FREEZING BY EARLY AFTERNOON. PRECIP CHANCES WILL THEN EXPAND EASTWARD...ESPECIALLY ACROSS THE NORTHERN CWA SATURDAY AFTERNOON BUT CHANCES STILL LOOK RATHER LOW BUT STILL WORTH A MENTION GIVEN STEADILY INCREASING DEEP LAYER MOISTURE /PRECIPITABLE WATER VALUES REACH 0.75 INCHES OR SO BY LATE DAY/ AND WARM ADVECTION. SOUTH TO SOUTHEAST WINDS WILL BECOME BREEZY WHICH WILL HELP HIGHS WARM INTO LOW TO MID 40S NORTH AND MID TO UPPER 40S SOUTH. IT IS ALSO IMPORTANT TO NOTE THAT DEW POINTS WILL BE ON THE RISE AS WELL WHICH WILL COMBINE WITH THE STEADY WINDS AND MILD TEMPS TO PROVIDE INCREASINGLY EFFICIENT SNOW MELT THROUGH THE AFTERNOON. MORE ON THIS BELOW... SATURDAY NIGHT AND SUNDAY...THE SOUTHWEST UPPER LOW WILL BE LIFTING ACROSS THE SOUTHERN HIGH PLAINS AND PHASING WITH THE CENTRAL CANADA UPPER TROUGH WHICH WILL BE SHARPENING AS IT PIVOTS SOUTHEASTWARD. THE MAIN SURFACE LOW IS EXPECTED TO ORGANIZE IN VICINITY OF THE SOUTHERN UPPER LOW ACROSS WESTERN KANSAS BY SATURDAY EVENING WITH AN INVERTED TROUGH EXTENDING NORTHWARD INTO WESTERN ONTARIO. GULF MOISTURE WILL CONTINUE TO STREAM NORTHWARD AHEAD OF THE LOW AS 60KT LOW LEVEL JET SPREADS ACROSS MISSOURI...ILLINOIS...AND LAKE MICHIGAN LATER SATURDAY EVENING. PRECIPITABLE WATER VALUES WILL FURTHER SURGE REACHING THE 1 TO PERHAPS 1.25 INCH RANGE WHICH WILL COMBINE WITH INCREASED ASCENT TO PRODUCE WIDESPREAD RAIN ACROSS THE MID-MISSISSIPPI RIVER VALLEY WHICH WILL THEN SPREAD EASTWARD DURING THE EVENING AND OVERNIGHT HOURS. THE UPPER LOW WILL BE TO THE WEST OF THE AREA BY SUNDAY MORNING WHICH WILL LIKELY BRING A DRY SLOT INTO THE AREA SOMETIME SUNDAY MORNING. INSTABILITY DOES INCREASE AS WELL...POTENTIALLY WITH ENOUGH ELEVATED INSTABILITY TO SUPPORT SOME THUNDER POTENTIAL ON THE LEADING EDGE OF THE DRY SLOT. FURTHERMORE...SOME MINIMAL SURFACE INSTABILITY COULD DEVELOP AS WELL WHICH WOULD POSE AN ADDITIONAL THUNDER THREAT...ESPECIALLY ALONG THE APPROACHING COLD FRONT WHICH WILL CROSS THE AREA LATER IN THE DAY. HOWEVER...THE DEEPER DRY AIR OF THE DRY SLOT MAY PRECLUDE MUCH IF ANY DEVELOPMENT ALONG THE FRONT IF SURFACE BASED INSTABILITY DOES IN FACT DEVELOP. STILL TOO EARLY TO HAVE ANY HIGH DEGREE OF CONFIDENCE IN THUNDER POTENTIAL BUT FEEL THIS BEARS WATCHING GIVEN THE HIGH DEGREE OF DEEP LAYER WIND SHEAR AND FAIRLY STRONG LOW LEVEL WIND FIELD. HIGH TEMPS SUNDAY LOOK TO RANGE FROM THE MID 40S NORTHWEST TO THE MID 50S SOUTHEAST. PRECIP AMOUNTS/FLOODING POTENTIAL...FORECAST GUIDANCE IS IN PRETTY GOOD AGREEMENT WITH THE TRACK OF LOW LEVEL FEATURES BUT DO DIFFER IN THE PLACEMENT OF OTHER FEATURES SUCH AS THE PATH OF THE UPPER JET CORE. QPF OUTPUT DOES DIFFER SOMEWHAT AS A RESULT...ESPECIALLY IN PLACEMENT OF HEAVIEST VALUES. ARRIVAL TIMING MAY ALSO NEED ADJUSTMENT WITH SOME GUIDANCE BEING SLOWER BUT RIGHT NOW THE DIFFERENCES ARE ON THE ORDER OF A FEW HOURS. THE WESTERN AND NORTHERN CWA CONTINUES TO LOOK TO HAVE THE BEST CHANCE AT RECEIVING PEAK RAINFALL AMOUNTS...OR ROUGHLY FROM CHICAGO TO PONTIAC AND POINTS WEST BUT THE ENTIRE CWA DOES LOOK TO SEE RAINFALL. GIVEN THE PRECIPITABLE WATER VALUES AND DURATION OF FORCING...AMOUNTS OF 0.75-1.00 INCHES ARE PLAUSIBLE IN THE NORTH AND WEST WITH LESSER AMOUNTS SOUTHEAST. IF CONVECTION CAN DEVELOP SUNDAY MORNING THEN AMOUNTS WOULD BE HIGHER IN SPOTS BUT IT IS POSSIBLE THAT THE BEST CHANCE FOR CONVECTION COULD END UP BEING ACROSS THE SOUTHERN/EASTERN CWA GIVEN THE LIKELY TRACK OF THE DRY SLOT AND ARRIVAL OF INSTABILITY. SO CONFIDENCE IN SPECIFIC AMOUNTS AND WHERE THEY OCCUR IS STILL LIMITED. HOWEVER...EVEN SOMEWHAT LOWER AMOUNTS THAN THOSE ABOVE ARE STILL A CONCERN GIVEN THE AMOUNT OF WATER IN THE CURRENT SNOW PACK. REFERENCE HYDROLOGY SECTION BELOW AND ESFLOT PRODUCT FOR MORE DETAILS. SUNDAY NIGHT AND MONDAY...TIMING DIFFERENCES BECOME MORE CRITICAL AS THE SYSTEM DEPARTS SUNDAY NIGHT AND MONDAY. IN TERMS OF FRONTAL TIMING...THERE IS GOOD AGREEMENT ON HAVING THE COLD FRONT SWEEP ACROSS THE AREA SUNDAY AFTERNOON WHICH ALLOWS COLDER AIR TO ARRIVE...BUT THE SPEED WITH WHICH IT ARRIVES IS NOT QUITE CLEAR. THE ECMWF/GEM REMAIN SLOWER WITH THE PASSAGE OF THE UPPER TROUGH AXIS DELAYING THE ARRIVAL OF COLDEST AIR...AS WELL AS THE ATTENDANT DEFORMATION FORCING HOLDING IT OFF UNTIL CLOSER TO MONDAY MORNING. THE NAM AND GFS ARE FASTER WITH THE UPPER TROUGH AND ARRIVAL OF COLD AIR. THIS WILL PLAY HAVOC WITH PRECIP TIMING AND TYPE BEHIND THE FRONT INTO MONDAY MORNING. WILL NEED TO MONITOR THIS PERIOD AS THERE IS AT LEAST SOME SUPPORT FOR MEASURABLE PRECIP MONDAY. MDB LONG TERM...MONDAY NIGHT THROUGH FRIDAY... THE EXTENDED PERIOD WILL FEATURE A FAIRLY PROGRESSIVE NORTHWEST TO PERHAPS ZONAL FLOW WITH SEVERAL WEAK SYSTEMS TO AFFECT PART OF THE REGION/GREAT LAKES. TIMING ANY OF THESE FEATURES IS SOMEWHAT DIFFICULT AS THEIR STRENGTH/LOCATION CONTINUES TO FLUCTUATE FROM RUN TO RUN AS WELL AS FROM MODEL TO MODEL. WHILE THERE WILL BE A FEW CHANCES FOR PRECIP...WILL CONTINUE WITH MAINLY A DRY FORECAST DUE TO LOW CONFIDENCE THOUGH HAVE INCLUDED A SLIGHT CHANCE OF SHOWERS ON FRIDAY AS THERE HAS BEEN SOME CONTINUITY DURING THIS TIME PERIOD. SHOULD PRECIP CHANCES/TRENDS INCREASE...PRECIP TYPE WILL BECOME A CONCERN DEPENDING ON TIME OF DAY. TEMPERATURES ARE EQUALLY CHALLENGING...DEPENDING ON THE TIMING OF THESE FEATURES AND THE EXTENT OF COLD AIR THEY BRING WITH THEM. ECMWF HAD BEEN FAIRLY CONSISTENT WITH A PUSH OF COLDER AIR THURSDAY INTO FRIDAY WHICH IS NOW GONE WHILE THE GFS IS NOW MUCH COLDER. HAVE TRENDED MIDDLE OF THE ROAD WITH TEMPS AND GIVEN MID MARCH SUNSHINE... LACK OF ANY SIGNIFICANT COLD AIR PUSH WOULD SUPPORT TEMPS NEAR SEASONAL NORMALS. CMS && .HYDROLOGY... 234 PM CST SOME AREAS OF THE FORECAST AREA MAY SEE 0.75-1.00 INCHES OF RAINFALL FROM SATURDAY THROUGH SUNDAY...WITH THE BULK EXPECTED SATURDAY EVENING/NIGHT. AT THIS POINT...THESE RAINFALL AMOUNTS ARE EXPECTED GENERALLY WEST OF A LINE FROM CHICAGO TO PONTIAC WITH LESSER AMOUNTS SOUTHEAST BUT THERE IS SOME OPPORTUNITY FOR THE LOCATION TO NEED ADJUSTMENT. IN ADDITION...SOME CONVECTIVE RAINFALL IS POSSIBLE WHICH COULD RESULT IN LOCALLY HIGHER AMOUNTS. OBSERVED SNOW CORE WATER EQUIVALENTS RANGE FROM AROUND AN INCH TO AROUND 2.5 INCHES WHERE THE DEEPEST SNOW EXISTS...MAINLY NORTH OF INTERSTATE 80. FROST DEPTH REMAINS IN THE 6 TO 10 INCH RANGE. THE EXPECTATION IS THAT THE SNOW WILL MELT AND RUNOFF WILL BE REALIZED BEFORE THE FROST MELTS SIGNIFICANTLY DUE TO THE INSULATING EFFECTS OF THE SNOW PACK. SNOW MELT WILL COMMENCE BEFORE THE BULK OF THE RAINFALL WHICH COULD ALLOW SOME OF THE RUNOFF INTO AREA RIVERS AND STREAMS TO MAKE PROGRESS DOWNSTREAM BUT THIS WOULD LIKELY BE MINIMAL. MOST MELT WILL LIKELY OCCUR WITH THE RAINFALL SO RIVER RISES WILL OCCUR AND SOME RIVERS COULD EXCEED FLOOD STAGE LATER SUNDAY/MONDAY. AREAL OVERLAND FLOODING IS A POSSIBILITY...MAINLY IN LOW LYING AND POORLY DRAINED AREAS. REFERENCE ESFLOT FOR ADDITIONAL INFORMATION. && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * CHANCE OF SOME LIGHT RAIN THIS AFTERNOON. * RAIN AND FOG TIMING TONIGHT. * MVFR CIGS AND VISIBILITY LIKELY AFTER 06 UTC SATURDAY NIGHT. * IFR CIGS AND VISIBILITY POSSIBLE BY DAYBREAK ON SUNDAY MORNING. * LLWS POSSIBLE SATURDAY NIGHT. KJB //DISCUSSION...UPDATED 06Z... THE MAIN CONCERNS DURING THE PERIOD WILL BE WITH OUR NEXT STORM SYSTEM...WHICH IS CURRENTLY TAKING SHAPE ACROSS THE FRONT RANGE OF THE COLORADO ROCKIES. THIS SYSTEM IS ALREADY TRANSPORTING WARM AND MOIST AIR NORTHWARD ACROSS THE PLAINS AND INTO THE MID MISSOURI VALLEY WITH SCATTERED SHOWERS AND EVEN SOME THUNDERSTORMS ONGOING ACROSS THIS REGION. IT APPEARS SOME OF THESE SHOWERS MAY EFFECT KRFD AROUND DAYBREAK...AND WITH TEMPERATURES POSSIBLY NEAR FREEZING...I OPTED TO LEAVE THE -FZRA IN THE NEW TAF FROM 12-14 UTC THIS MORNING. HOWEVER...I HAVE LOW CONFIDENCE IN THE FREEZING THREAT AS TEMPERATURES MAY ACTUALLY JUMP ABOVE FREEZING PRIOR TO THE ONSET OF THE PRECIPITATION. IN ADDITION...I AM NOT SURE HOW MUCH IF ANY PRECIP WILL ACTUALLY FALL THIS MORNING. THERE IS STILL SOME DRY AIR IN THE LOW LEVELS TO OVERCOME...AND IT APPEARS THAT CIGS WILL STILL BE AT OR ABOVE 9000 FEET THROUGH 15 UTC. WITH THIS IN MIND...WE MAY NOT SEE MORE THAN A FEW SPRINKLES DURING THE EARLY MORNING HOURS AT KRFD. IT APPEARS MOST OF THE DAY PRIOR TO 20 UTC WILL BE DRY. AFTER 20 UTC WE COULD GET ANOTHER BATCH OF LIGHT RAIN ACROSS THE TAF SITES. THIS ALSO APPEARS AS THOUGH IT WILL BE RATHER LIGHT...AND I HAVE OPTED TO KEEP THE PROB 30 GROUP GOING FOR THIS ACTIVITY. I DID...HOWEVER...TRIM THE END TIME OF THE PROB 30 GROUP TO 01 UTC AS IT APPEARS THERE WILL BE QUITE A BIT OF DRY TIME THIS EVENING AHEAD OF THE MAIN BATCH OF RAIN. RAIN SHOULD ONSET AROUND OR SHORTLY AFTER 03 UTC THIS EVENING AT KRFD AND AFTER 06 UTC AT THE EASTERN TERMINALS AS THE MAIN STORM SYSTEM APPROACHES THE AREA. IT APPEARS THE RAIN WILL BE MODERATE AT TIMES WITH CIGS GRADUALLY LOWERING INTO THE IFR CATEGORY BY EARLY SUNDAY. VISIBILITIES WILL ALSO BE DEGRADING INTO AT LEAST THE MVFR RANGE IN RAIN AND FOG. LOW CLOUDS AND FOG LOOK TO CONTINUE INTO THE DAY ON SUNDAY AS THE SURFACE LOW MOVES OVERHEAD AND SURFACE DEW POINTS PEAK IN THE LOWER TO MIDDLE 40S. THERE IS ALSO A CHANCE OF LLWS SATURDAY NIGHT AS IT APPEARS THE A SOUTHWESTERLY 50-55 LOW LEVEL JET WILL DEVELOP AROUND 2,000 FT AGL. SURFACE WINDS DURING THIS TIME ARE EXPECTED TO BE AROUND 10 KT OUT OF THE SOUTH. I HAVE OPTED NOT TO ADD THIS TO THE NEW TAF...BUT IT MAY NEED TO BE ADDED AT A LATER TIME IF THESE CONDITIONS APPEAR TO BE SETTING UP. KJB //ORD AND MDW CONFIDENCE...UPDATED 06Z... * LOW CONFIDENCE ON ANY LIGHT RAIN AFFECTING THE TERMINALS THIS AFTERNOON. * MEDIUM TO HIGH CONFIDENCE IN RAIN AND FOG REDUCING VISIBILITIES UNDER 4 MILES LATER SUNDAY NIGHT AFTER 06 UTC. * MEDIUM CONFIDENCE IN IFR CIGS TOWARDS DAYBREAK SUNDAY. * LOW TO MEDIUM CONFIDENCE IN LLWS SATURDAY NIGHT. KJB //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY...RAIN AND FOG WITH LIKELY IFR. A CHANCE FOR A MIX WITH SNOW DURING THE NIGHT. MONDAY...SLIGHT CHANCE OF RAIN AND SNOW WITH MVFR. TUESDAY-THURSDAY...VFR. MTF && .MARINE... 228 AM CST A STORM SYSTEM...CURRENTLY TAKING SHAPE ACROSS THE FRONT RANGE OF THE COLORADO ROCKIES...WILL SPLIT OFF INTO TWO SYSTEMS. ONE WILL RACE NORTHEASTWARD ACROSS ONTARIO BY SUNDAY...WHILE THE SECOND SYSTEM MOVES TOWARDS THE SOUTHERN END OF LAKE MICHIGAN BY SUNDAY EVENING. THIS SECOND SYSTEM LOOKS TO HAVE A LARGE IMPACT ON THE WINDS OVER THE LAKE THROUGH THE WEEKEND. SOUTHERLY WINDS WILL OCCUR TODAY AND TONIGHT...UP AROUND 25 KT AHEAD OF THIS SYSTEM. THEN AS THE SURFACE LOW APPROACHES THE LAKE ON SUNDAY...THE WINDS WILL BECOME NORTH-NORTHEASTERLY AND INCREASE UP AROUND 30 KT...ESPECIALLY ACROSS THE NORTHERN END OF THE LAKE. GALE FORCE WINDS ARE QUITE POSSIBLE WITH THIS SYSTEM...BUT UNCERTAINTIES REMAIN AS TO THE EXACT TRACK OF THIS SYSTEM...AND HENCE WHERE THE STRONGEST WINDS WILL BE. ONCE THIS LOW PASSES OVER THE LAKE...A PERIOD OF NORTHWESTERLY WINDS OF 25 TO 30 KT LOOKS LIKELY INTO AT LEAST MONDAY. HOWEVER...THESE NORTHWESTERLY WINDS COULD CONTINUE INTO MIDWEEK AS IT APPEARS A WEAK CLIPPER SYSTEM MAY MOVE ACROSS THE LAKE SOMETIME ON TUESDAY OR TUESDAY EVENING. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1227 AM CST SAT MAR 9 2013 .DISCUSSION... 924 PM CST NO REAL BIG CHANGES TO GOING FORECAST TONIGHT...WITH ONLY MINOR EDITS TO POP/WX FOR AREAS ACROSS NORTHWEST ILLINOIS. LATEST SATELLITE IMAGERY DEPICTING MID/UPPER LEVEL CLOUD COVER CONTINUING TO STREAM NORTHEAST ACROSS THE REGION THIS EVENING...AS SOUTHWESTERLY FLOW CONTINUES OUT AHEAD OF AN APPROACHING LONGWAVE TROUGH OVER THE WESTERN CONUS. THIS IS USHERING IN A WARMER AND MORE MOIST ENVIRONMENT WITH LATEST RAP ANALYSIS DEPICTING STRONG WAA OCCURRING ACROSS MUCH OF THE PLAINS...AND CAN BE NOTED VIA THE ABUNDANCE OF CLOUD COVER AS WELL AS THE WIDESPREAD PRECIP SHIELD IN THIS LOCATION. ALTHOUGH THE STRONGEST WAA WILL REMAIN JUST TO THE WEST OF THE CWA...LATEST SHORT TERM GUIDANCE IS INDICATING THAT SOME LIGHT PRECIP DEVELOPMENT COULD OCCUR ACROSS NORTHWEST ILLINOIS TONIGHT AS THIS WAA WING CONTINUES TO LIFT NORTH/NORTHEAST. PRECIP DEVELOPMENT LATE TONIGHT ACROSS AREAS ALONG AND WEST OF INTERSTATE 39 DOES SEEM REASONABLE WITH THIS BETTER FORCING ALREADY INCHING CLOSER TO THE CWA. ALTHOUGH THIS FORCING WILL REMAIN RATHER WEAK...IT MAY BE ENOUGH OF A PERSISTENT FEATURE TO OVERCOME SOME DRIER AIR IN PLACE. THERMAL PROFILES WILL SUPPORT PRECIP OF THE LIQUID TYPE...BUT WITH THE POSSIBILITY OF A BRIEF WINDOW OF LIGHT FREEZING RAIN. ALTHOUGH...WARMING TONIGHT SHOULD MITIGATE ANY OVERALL FREEZING RAIN POTENTIAL WITH SURFACE TEMPERATURES EXPECTED TO BE HOVERING AROUND FREEZING IF NOT BEGINNING TO RISE JUST ABOVE BY THE TIME THIS PRECIP ARRIVES. SO HAVE MADE MENTION OF A SLIGHT CHANCE OF LIGHT RAIN/LIGHT FREEZING RAIN FOR LATE TONIGHT INTO EARLY SATURDAY MORNING BEFORE TEMPERATURES CONTINUE TO RISE THROUGH MID SATURDAY MORNING WITH ONLY RAIN THEN EXPECTED. RODRIGUEZ //PREV DISCUSSION... 234 PM CST THE AREA WILL QUICKLY SHIFT FROM WINTER TO SPRING WEATHER THIS WEEKEND WITH EXPECTED RAINFALL/SNOW MELT WITH WARMING TEMPERATURES POSING A FLOOD THREAT...WITH THUNDERSTORMS NOT OUT OF THE QUESTION BY SUNDAY. UPS AND DOWNS IN TEMPERATURES ARE EXPECTED NEXT WEEK WITH A SERIES OF WEAKER SYSTEMS BRINGING PERIODIC LOW CHANCES FOR PRECIPITATION. SYNOPSIS...EARLY AFTERNOON WATER VAPOR IMAGERY SHOWS UPPER RIDGING BUILDING ACROSS THE MISSISSIPPI RIVER VALLEY INTO THE LOCAL AREA IN RESPONSE TO A DEEP CLOSED UPPER LOW ROTATING INTO THE DESERT SOUTHWEST. THIS TROUGH IS SPLIT FROM A TROUGH THAT IS POSITIONED OVER CENTRAL CANADA WITH A TROUGH AXIS SHIFTING TOWARDS WESTERN SASKATCHEWAN. THESE TWO FEATURES WILL BE THE MAIN DRIVERS OF EXPECTED RAINFALL THIS WEEKEND. AT THE SURFACE...A LARGE AREA OF HIGH PRESSURE IS EXITING THE LOCAL AREA TO THE EAST. WEAK LOW PRESSURE IS OVER SOUTHERN MANITOBA AND IS DRIFTING EASTWARD. TONIGHT AND SATURDAY...QUIET WEATHER WILL CONTINUE TONIGHT WITH THE UPPER RIDGE CRESTING THE AREA THIS EVENING. THE BIG SOUTHWEST TROUGH WILL BE MOVING EASTWARD WITH HEIGHT FALLS AHEAD OF IT AND BEHIND THE RIDGE ALLOWING LOW PRESSURE TO DEVELOP IN THE LEE OF THE ROCKIES. A 50+KT LOW LEVEL JET WILL SET UP ACROSS THE PLAINS RESULTING IN A STRONG PUSH OF HIGH THETA-E LOW LEVEL AIR ACROSS THE SOUTHERN AND CENTRAL PLAINS. HIGH LEVEL MOISTURE WILL BE SPREAD NORTHEASTWARD SUPPORTING AN INCREASE IN MID AND HIGH LEVEL CLOUD COVER OVERNIGHT. THE PRESSURE GRADIENT WILL BE WEAK ACROSS THE AREA EARLY BUT WILL TIGHTEN OVERNIGHT SO WINDS MAY DROP OFF FOR A TIME EARLY BEFORE INCREASING SOMEWHAT OVERNIGHT. LOW TEMPS WILL BE THE MAIN CHALLENGE AND MAY OCCUR DURING THE EVENING BUT SOME WARMING MAY OCCUR LATE AS CLOUDS AND WINDS INCREASE AND WARM ADVECTION IS UNDERWAY ALOFT. WILL GO AHEAD AND SHOW A STEADY OR WARMING TREND OVERNIGHT. LIGHT PRECIP BECOMES A CONCERN BY SATURDAY MORNING AS WAVES OF WARM ADVECTION BECOME MORE FOCUSED AND MOISTURE DEEPENS. THIS IS WHERE TEMPS WILL BECOME CRITICAL BECAUSE CHANCES FOR LIGHT PRECIP MAY BEGIN EARLY ENOUGH TO FALL AS FREEZING RAIN. SIGNALS FOR PRECIP ARE NOT ALL THAT ORGANIZED UNTIL SATURDAY AFTERNOON BUT WESTERN AREAS MAY HAVE DEEP ENOUGH MOISTURE AND ENOUGH WARM ASCENT OCCURRING ALOFT TO SEE LIGHT RAIN...OR FREEZING RAIN IF TEMPS START OUT BELOW FREEZING...BY LATE SATURDAY MORNING. ANY FREEZING PRECIP WILL QUICKLY END AS TEMPS WARM WELL ABOVE FREEZING BY EARLY AFTERNOON. PRECIP CHANCES WILL THEN EXPAND EASTWARD...ESPECIALLY ACROSS THE NORTHERN CWA SATURDAY AFTERNOON BUT CHANCES STILL LOOK RATHER LOW BUT STILL WORTH A MENTION GIVEN STEADILY INCREASING DEEP LAYER MOISTURE /PRECIPITABLE WATER VALUES REACH 0.75 INCHES OR SO BY LATE DAY/ AND WARM ADVECTION. SOUTH TO SOUTHEAST WINDS WILL BECOME BREEZY WHICH WILL HELP HIGHS WARM INTO LOW TO MID 40S NORTH AND MID TO UPPER 40S SOUTH. IT IS ALSO IMPORTANT TO NOTE THAT DEW POINTS WILL BE ON THE RISE AS WELL WHICH WILL COMBINE WITH THE STEADY WINDS AND MILD TEMPS TO PROVIDE INCREASINGLY EFFICIENT SNOW MELT THROUGH THE AFTERNOON. MORE ON THIS BELOW... SATURDAY NIGHT AND SUNDAY...THE SOUTHWEST UPPER LOW WILL BE LIFTING ACROSS THE SOUTHERN HIGH PLAINS AND PHASING WITH THE CENTRAL CANADA UPPER TROUGH WHICH WILL BE SHARPENING AS IT PIVOTS SOUTHEASTWARD. THE MAIN SURFACE LOW IS EXPECTED TO ORGANIZE IN VICINITY OF THE SOUTHERN UPPER LOW ACROSS WESTERN KANSAS BY SATURDAY EVENING WITH AN INVERTED TROUGH EXTENDING NORTHWARD INTO WESTERN ONTARIO. GULF MOISTURE WILL CONTINUE TO STREAM NORTHWARD AHEAD OF THE LOW AS 60KT LOW LEVEL JET SPREADS ACROSS MISSOURI...ILLINOIS...AND LAKE MICHIGAN LATER SATURDAY EVENING. PRECIPITABLE WATER VALUES WILL FURTHER SURGE REACHING THE 1 TO PERHAPS 1.25 INCH RANGE WHICH WILL COMBINE WITH INCREASED ASCENT TO PRODUCE WIDESPREAD RAIN ACROSS THE MID-MISSISSIPPI RIVER VALLEY WHICH WILL THEN SPREAD EASTWARD DURING THE EVENING AND OVERNIGHT HOURS. THE UPPER LOW WILL BE TO THE WEST OF THE AREA BY SUNDAY MORNING WHICH WILL LIKELY BRING A DRY SLOT INTO THE AREA SOMETIME SUNDAY MORNING. INSTABILITY DOES INCREASE AS WELL...POTENTIALLY WITH ENOUGH ELEVATED INSTABILITY TO SUPPORT SOME THUNDER POTENTIAL ON THE LEADING EDGE OF THE DRY SLOT. FURTHERMORE...SOME MINIMAL SURFACE INSTABILITY COULD DEVELOP AS WELL WHICH WOULD POSE AN ADDITIONAL THUNDER THREAT...ESPECIALLY ALONG THE APPROACHING COLD FRONT WHICH WILL CROSS THE AREA LATER IN THE DAY. HOWEVER...THE DEEPER DRY AIR OF THE DRY SLOT MAY PRECLUDE MUCH IF ANY DEVELOPMENT ALONG THE FRONT IF SURFACE BASED INSTABILITY DOES IN FACT DEVELOP. STILL TOO EARLY TO HAVE ANY HIGH DEGREE OF CONFIDENCE IN THUNDER POTENTIAL BUT FEEL THIS BEARS WATCHING GIVEN THE HIGH DEGREE OF DEEP LAYER WIND SHEAR AND FAIRLY STRONG LOW LEVEL WIND FIELD. HIGH TEMPS SUNDAY LOOK TO RANGE FROM THE MID 40S NORTHWEST TO THE MID 50S SOUTHEAST. PRECIP AMOUNTS/FLOODING POTENTIAL...FORECAST GUIDANCE IS IN PRETTY GOOD AGREEMENT WITH THE TRACK OF LOW LEVEL FEATURES BUT DO DIFFER IN THE PLACEMENT OF OTHER FEATURES SUCH AS THE PATH OF THE UPPER JET CORE. QPF OUTPUT DOES DIFFER SOMEWHAT AS A RESULT...ESPECIALLY IN PLACEMENT OF HEAVIEST VALUES. ARRIVAL TIMING MAY ALSO NEED ADJUSTMENT WITH SOME GUIDANCE BEING SLOWER BUT RIGHT NOW THE DIFFERENCES ARE ON THE ORDER OF A FEW HOURS. THE WESTERN AND NORTHERN CWA CONTINUES TO LOOK TO HAVE THE BEST CHANCE AT RECEIVING PEAK RAINFALL AMOUNTS...OR ROUGHLY FROM CHICAGO TO PONTIAC AND POINTS WEST BUT THE ENTIRE CWA DOES LOOK TO SEE RAINFALL. GIVEN THE PRECIPITABLE WATER VALUES AND DURATION OF FORCING...AMOUNTS OF 0.75-1.00 INCHES ARE PLAUSIBLE IN THE NORTH AND WEST WITH LESSER AMOUNTS SOUTHEAST. IF CONVECTION CAN DEVELOP SUNDAY MORNING THEN AMOUNTS WOULD BE HIGHER IN SPOTS BUT IT IS POSSIBLE THAT THE BEST CHANCE FOR CONVECTION COULD END UP BEING ACROSS THE SOUTHERN/EASTERN CWA GIVEN THE LIKELY TRACK OF THE DRY SLOT AND ARRIVAL OF INSTABILITY. SO CONFIDENCE IN SPECIFIC AMOUNTS AND WHERE THEY OCCUR IS STILL LIMITED. HOWEVER...EVEN SOMEWHAT LOWER AMOUNTS THAN THOSE ABOVE ARE STILL A CONCERN GIVEN THE AMOUNT OF WATER IN THE CURRENT SNOW PACK. REFERENCE HYDROLOGY SECTION BELOW AND ESFLOT PRODUCT FOR MORE DETAILS. SUNDAY NIGHT AND MONDAY...TIMING DIFFERENCES BECOME MORE CRITICAL AS THE SYSTEM DEPARTS SUNDAY NIGHT AND MONDAY. IN TERMS OF FRONTAL TIMING...THERE IS GOOD AGREEMENT ON HAVING THE COLD FRONT SWEEP ACROSS THE AREA SUNDAY AFTERNOON WHICH ALLOWS COLDER AIR TO ARRIVE...BUT THE SPEED WITH WHICH IT ARRIVES IS NOT QUITE CLEAR. THE ECMWF/GEM REMAIN SLOWER WITH THE PASSAGE OF THE UPPER TROUGH AXIS DELAYING THE ARRIVAL OF COLDEST AIR...AS WELL AS THE ATTENDANT DEFORMATION FORCING HOLDING IT OFF UNTIL CLOSER TO MONDAY MORNING. THE NAM AND GFS ARE FASTER WITH THE UPPER TROUGH AND ARRIVAL OF COLD AIR. THIS WILL PLAY HAVOC WITH PRECIP TIMING AND TYPE BEHIND THE FRONT INTO MONDAY MORNING. WILL NEED TO MONITOR THIS PERIOD AS THERE IS AT LEAST SOME SUPPORT FOR MEASURABLE PRECIP MONDAY. MDB LONG TERM...MONDAY NIGHT THROUGH FRIDAY... THE EXTENDED PERIOD WILL FEATURE A FAIRLY PROGRESSIVE NORTHWEST TO PERHAPS ZONAL FLOW WITH SEVERAL WEAK SYSTEMS TO AFFECT PART OF THE REGION/GREAT LAKES. TIMING ANY OF THESE FEATURES IS SOMEWHAT DIFFICULT AS THEIR STRENGTH/LOCATION CONTINUES TO FLUCTUATE FROM RUN TO RUN AS WELL AS FROM MODEL TO MODEL. WHILE THERE WILL BE A FEW CHANCES FOR PRECIP...WILL CONTINUE WITH MAINLY A DRY FORECAST DUE TO LOW CONFIDENCE THOUGH HAVE INCLUDED A SLIGHT CHANCE OF SHOWERS ON FRIDAY AS THERE HAS BEEN SOME CONTINUITY DURING THIS TIME PERIOD. SHOULD PRECIP CHANCES/TRENDS INCREASE...PRECIP TYPE WILL BECOME A CONCERN DEPENDING ON TIME OF DAY. TEMPERATURES ARE EQUALLY CHALLENGING...DEPENDING ON THE TIMING OF THESE FEATURES AND THE EXTENT OF COLD AIR THEY BRING WITH THEM. ECMWF HAD BEEN FAIRLY CONSISTENT WITH A PUSH OF COLDER AIR THURSDAY INTO FRIDAY WHICH IS NOW GONE WHILE THE GFS IS NOW MUCH COLDER. HAVE TRENDED MIDDLE OF THE ROAD WITH TEMPS AND GIVEN MID MARCH SUNSHINE... LACK OF ANY SIGNIFICANT COLD AIR PUSH WOULD SUPPORT TEMPS NEAR SEASONAL NORMALS. CMS && .HYDROLOGY... 234 PM CST SOME AREAS OF THE FORECAST AREA MAY SEE 0.75-1.00 INCHES OF RAINFALL FROM SATURDAY THROUGH SUNDAY...WITH THE BULK EXPECTED SATURDAY EVENING/NIGHT. AT THIS POINT...THESE RAINFALL AMOUNTS ARE EXPECTED GENERALLY WEST OF A LINE FROM CHICAGO TO PONTIAC WITH LESSER AMOUNTS SOUTHEAST BUT THERE IS SOME OPPORTUNITY FOR THE LOCATION TO NEED ADJUSTMENT. IN ADDITION...SOME CONVECTIVE RAINFALL IS POSSIBLE WHICH COULD RESULT IN LOCALLY HIGHER AMOUNTS. OBSERVED SNOW CORE WATER EQUIVALENTS RANGE FROM AROUND AN INCH TO AROUND 2.5 INCHES WHERE THE DEEPEST SNOW EXISTS...MAINLY NORTH OF INTERSTATE 80. FROST DEPTH REMAINS IN THE 6 TO 10 INCH RANGE. THE EXPECTATION IS THAT THE SNOW WILL MELT AND RUNOFF WILL BE REALIZED BEFORE THE FROST MELTS SIGNIFICANTLY DUE TO THE INSULATING EFFECTS OF THE SNOW PACK. SNOW MELT WILL COMMENCE BEFORE THE BULK OF THE RAINFALL WHICH COULD ALLOW SOME OF THE RUNOFF INTO AREA RIVERS AND STREAMS TO MAKE PROGRESS DOWNSTREAM BUT THIS WOULD LIKELY BE MINIMAL. MOST MELT WILL LIKELY OCCUR WITH THE RAINFALL SO RIVER RISES WILL OCCUR AND SOME RIVERS COULD EXCEED FLOOD STAGE LATER SUNDAY/MONDAY. AREAL OVERLAND FLOODING IS A POSSIBILITY...MAINLY IN LOW LYING AND POORLY DRAINED AREAS. REFERENCE ESFLOT FOR ADDITIONAL INFORMATION. && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * CHANCE OF SOME LIGHT RAIN THIS AFTERNOON. * RAIN AND FOG TIMING TONIGHT. * MVFR CIGS AND VISIBILITY LIKELY AFTER 06 UTC SATURDAY NIGHT. * IFR CIGS AND VISIBILITY POSSIBLE BY DAYBREAK ON SUNDAY MORNING. * LLWS POSSIBLE SATURDAY NIGHT. KJB //DISCUSSION...UPDATED 06Z... THE MAIN CONCERNS DURING THE PERIOD WILL BE WITH OUR NEXT STORM SYSTEM...WHICH IS CURRENTLY TAKING SHAPE ACROSS THE FRONT RANGE OF THE COLORADO ROCKIES. THIS SYSTEM IS ALREADY TRANSPORTING WARM AND MOIST AIR NORTHWARD ACROSS THE PLAINS AND INTO THE MID MISSOURI VALLEY WITH SCATTERED SHOWERS AND EVEN SOME THUNDERSTORMS ONGOING ACROSS THIS REGION. IT APPEARS SOME OF THESE SHOWERS MAY EFFECT KRFD AROUND DAYBREAK...AND WITH TEMPERATURES POSSIBLY NEAR FREEZING...I OPTED TO LEAVE THE -FZRA IN THE NEW TAF FROM 12-14 UTC THIS MORNING. HOWEVER...I HAVE LOW CONFIDENCE IN THE FREEZING THREAT AS TEMPERATURES MAY ACTUALLY JUMP ABOVE FREEZING PRIOR TO THE ONSET OF THE PRECIPITATION. IN ADDITION...I AM NOT SURE HOW MUCH IF ANY PRECIP WILL ACTUALLY FALL THIS MORNING. THERE IS STILL SOME DRY AIR IN THE LOW LEVELS TO OVERCOME...AND IT APPEARS THAT CIGS WILL STILL BE AT OR ABOVE 9000 FEET THROUGH 15 UTC. WITH THIS IN MIND...WE MAY NOT SEE MORE THAN A FEW SPRINKLES DURING THE EARLY MORNING HOURS AT KRFD. IT APPEARS MOST OF THE DAY PRIOR TO 20 UTC WILL BE DRY. AFTER 20 UTC WE COULD GET ANOTHER BATCH OF LIGHT RAIN ACROSS THE TAF SITES. THIS ALSO APPEARS AS THOUGH IT WILL BE RATHER LIGHT...AND I HAVE OPTED TO KEEP THE PROB 30 GROUP GOING FOR THIS ACTIVITY. I DID...HOWEVER...TRIM THE END TIME OF THE PROB 30 GROUP TO 01 UTC AS IT APPEARS THERE WILL BE QUITE A BIT OF DRY TIME THIS EVENING AHEAD OF THE MAIN BATCH OF RAIN. RAIN SHOULD ONSET AROUND OR SHORTLY AFTER 03 UTC THIS EVENING AT KRFD AND AFTER 06 UTC AT THE EASTERN TERMINALS AS THE MAIN STORM SYSTEM APPROACHES THE AREA. IT APPEARS THE RAIN WILL BE MODERATE AT TIMES WITH CIGS GRADUALLY LOWERING INTO THE IFR CATEGORY BY EARLY SUNDAY. VISIBILITIES WILL ALSO BE DEGRADING INTO AT LEAST THE MVFR RANGE IN RAIN AND FOG. LOW CLOUDS AND FOG LOOK TO CONTINUE INTO THE DAY ON SUNDAY AS THE SURFACE LOW MOVES OVERHEAD AND SURFACE DEW POINTS PEAK IN THE LOWER TO MIDDLE 40S. THERE IS ALSO A CHANCE OF LLWS SATURDAY NIGHT AS IT APPEARS THE A SOUTHWESTERLY 50-55 LOW LEVEL JET WILL DEVELOP AROUND 2,000 FT AGL. SURFACE WINDS DURING THIS TIME ARE EXPECTED TO BE AROUND 10 KT OUT OF THE SOUTH. I HAVE OPTED NOT TO ADD THIS TO THE NEW TAF...BUT IT MAY NEED TO BE ADDED AT A LATER TIME IF THESE CONDITIONS APPEAR TO BE SETTING UP. KJB //ORD AND MDW CONFIDENCE...UPDATED 06Z... * LOW CONFIDENCE ON ANY LIGHT RAIN AFFECTING THE TERMINALS THIS AFTERNOON. * MEDIUM TO HIGH CONFIDENCE IN RAIN AND FOG REDUCING VISIBILITIES UNDER 4 MILES LATER SUNDAY NIGHT AFTER 06 UTC. * MEDIUM CONFIDENCE IN IFR CIGS TOWARDS DAYBREAK SUNDAY. * LOW TO MEDIUM CONFIDENCE IN LLWS SATURDAY NIGHT. KJB //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY...RAIN AND FOG WITH LIKELY IFR. A CHANCE FOR A MIX WITH SNOW DURING THE NIGHT. MONDAY...SLIGHT CHANCE OF RAIN AND SNOW WITH MVFR. TUESDAY-THURSDAY...VFR. MTF && .MARINE... 125 PM CST THE HIGH PRESSURE THAT BROUGHT LIGHT AND VARIABLE WINDS TO LAKE MICHIGAN HAS MOVED EAST OF THE LAKE AND WINDS HAVE BECOME SOUTHERLY. AS DEEPENING LOW PRESSURE MOVES OUT OF THE ROCKIES AND INTO THE SOUTHERN PLAINS...WHILE THE HIGH MOVES SLOWLY TO THE EAST...THE GENERALLY SOUTHERLY WINDS WILL STRENGTHEN THROUGH THE WEEKEND. BY SATURDAY EVENING...THE HIGH WILL MOVE TO THE EASTERN SEABOARD WHILE THE LOW PRESSURE MOVER THE SOUTH HIGH PLAINS DEEPENS AND A TROUGH OF LOW PRESSURE ELONGATES TO ANOTHER...WEAKER LOW JUST NORTH OF MINNESOTA. SOUTHERLY WINDS WILL INCREASE TO AROUND 30 KT AS THE TROUGH OF LOW PRESSURE AND AN ASSOCIATED COLD FRONT APPROACH THE LAKE. THE COLD FRONT IS EXPECTED TO SWEEP ACROSS THE LAKE SUNDAY...WITH WINDS QUICKLY VEERING TO NORTHERLY. WITH HIGH PRESSURE QUICKLY BUILDING IN ACROSS THE LAKE BEHIND THE COLD FRONT...THE NORTHERLY WINDS WILL ONLY BRIEFLY INCREASE TO AROUND 25 KT SUNDAY NIGHT BEFORE DROPPING OFF TO 5 TO 10 KT BY MONDAY NIGHT. KREIN && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1151 PM CST FRI MAR 8 2013 .DISCUSSION... ISSUED 855 PM CST FRI MAR 8 2013 UPDATED THE FORECAST TO INCREASE CLOUD COVER TONIGHT AND ELEVATE LOW TEMPERATURES UP A DEGREE OR TWO. LOWS RANGE FROM NEAR 30F OVER EAST CENTRAL IL TO THE UPPER 30S FROM SPRINGFIELD SW. CONTINUE A CHANCE OF LIGHT RAIN SHOWERS OVERNIGHT OVER THE IL RIVER VALLEY... WITH BEST CHANCES NW OF THE IL RIVER LATE TONIGHT. 1031 MB HIGH PRESSURE OVER SE LOWER MI INTO OHIO AND EASTERN KY THAT PROVIDE A NICE DAY TO CENTRAL/SE IL WITH AMPLE SUNSHINE AND MILDER 40S WILL DRIFT INTO THE EASTERN GREAT LAKES SAT MORNING. 1001 MB LOW PRESSURE OVER SE CO WILL DEEPEN TO 997 MB NEAR THE SE CO/SW KS BORDER BY MIDDAY SAT WITH A FRONTAL BOUNDARY EXTENDING NE INTO FAR NW IA AND INTO MN. A WARM FRONT OVER SW MO INTO SOUTH CENTRAL NE WILL LIFT NE TOWARD SW IL SAT MORNING. STRONG WAA ADVECTION AND ISENTROPIC LIFT TO DEVELOP AND SPREAD LIGHT RAIN SHOWERS FROM CENTRAL AND WESTERN MO/IA INTO THE IL RIVER VALLEY OVERNIGHT INTO SAT MORNING MAINLY AFTER 09Z/3 AM. HRRR APPEARS TO WET WITH SHOWERS OVER MOST OF CWA OVERNIGHT. SINCE SOUNDINGS ARE QUITE DRY ESPECIALLY FROM I-55 EAST...THIS SHOULD KEEP AREAS FROM I-55 EAST DRY TONIGHT. TEMPS CURRENTLY IN THE MID TO UPPER 30S FROM MACOMB TO LINCOLN TO MATTOON NE AND 40-45F SW WILL SLIP ONLY A FEW MORE DEGREES DUE TO INCREASING/THICKENING MID/HIGH CLOUDS AND ESE WINDS OF 5-15 MPH. 07 && .AVIATION... ISSUED 1150 PM CST FRI MAR 8 2013 VFR CONDITIONS GENERALLY EXPECTED TO PREVAIL ACROSS THE CENTRAL IL TERMINAL AIRPORTS NEXT 24 HOURS THROUGH 06Z/MIDNIGHT SAT NIGHT. EXPECT BROKEN TO OVERCAST MID LEVEL CLOUDS TO LOWER FROM 10-15K FT TO 5-10K FT DURING OVERNIGHT INTO SAT MORNING...THEN LIFT BACK UP TO AROUND 10K FT SAT AFTERNOON INTO MID EVENING SAT. STRONG WAA AND ISENTROPIC LIFT TO GENERATE A LIGHT BAND OF SHOWERS OVER CENTRAL IL OVERNIGHT (SPI RECENTLY REPORTED SPRINKLES) WITH VSBYS STAYING ABOVE 5 MILES. MORE WIDESPREAD SHOWERS COULD BRUSH THE IL RIVER VALLEY NEAR PIA SAT MORNING AND POSSIBLY LINGER INTO EARLY SAT AFTERNOON WITH CEILINGS DOWN TO 3-5K FT AND VSBYS DOWN TO 5 MILES. SE WINDS 10-15 KTS OVERNIGHT TO INCREASE TO AROUND 15 KTS WITH GUSTS 20-25 KTS BY 15Z/SAT AND VEER SSE SAT EVENING. 1000 MB LOW PRESSURE OVER SE CO TO MOVE INTO SE KS BY 06Z/MID SAT NIGHT WITH A FRONTAL BOUNDARY INTO EASTERN IA. THIS WILL BRING A WIDESPREAD BAND OF MODERATE SHOWERS EAST TOWARD THE IL RIVER VALLEY AFTER 04Z/10 PM SAT AND LIKELY TO AFFECT PIA AND NEAR I-55 AT BMI AND SPI NEAR OR JUST AFTER 06Z/MID SAT NIGHT. 07 && .PREV DISCUSSION... ISSUED 300 PM CST FRI MAR 8 2013 OUR SURFACE PATTERN IS CURRENTLY DOMINATED BY HIGH PRESSURE EXTENDING FROM THE WESTERN GREAT LAKES ON SOUTH TO MISSISSIPPI...WHILE LOW PRESSURE IN THE SOUTHWEST STATES BEGINS TO MOVE ONSHORE AND DEVELOP UNDER A STRENGTHENING JET STREAM. THAT SYSTEM WILL BECOME OUR MAIN WEATHER ISSUE FOR THE NEXT 3 DAYS OR SO. OUTSIDE OF A BRIEF COOL DOWN ON MONDAY INTO TUESDAY...TEMPERATURES OVER THE NEXT WEEK WILL BE AT OR ABOVE NORMAL. SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT. MID AND HIGH CLOUDS WILL ADVANCE INTO ILLINOIS TONIGHT AS MID LEVEL WARM ADVECTION AND MOISTURE FLOWS BEGIN TO SATURATE THE LOWER TROPOSPHERE. FORECAST SOUNDINGS ARE INDICATING MOST AREAS WILL REMAIN DRY OVERNIGHT...ALTHOUGH WE CANT RULE OUT SOME LIGHT RAIN SHOWERS FOR OUR FAR WESTERN COUNTIES FROM SCHUYLER TO KNOX LATE TONIGHT. THE GFS IS THE ONLY MODEL TO BRING MUCH IN THE WAY OF MEASURABLE RAIN BEFORE 12Z TO OUR WESTERN COUNTIES...SO WE OPTED TO TREND VERY LOW ON THE POPS TONIGHT. ON SATURDAY...THE PRIMARY FORCING FOR PRECIP WILL REMAIN FOCUSED NORTHWEST OF I-55...WHILE AREAS SOUTHEAST OF I-55 REMAIN MAINLY DRY. WE KEPT LIKELY POPS TOWARD FULTON AND KNOX COUNTIES...WITH CHANCE POPS DOWN TO I-55. SOUTHEAST WINDS WILL BEGIN TO RESPOND TO THE PRESSURE FALLS BY SATURDAY AFTERNOON...WITH WINDS IN THE 20-30 MPH RANGE AT TIMES. THE GUSTY WINDS WILL CONTINUE TO AID THE MOISTURE TRANSPORT IN THE BOUNDARY LAYER SATURDAY NIGHT. WE KEPT CATEGORICAL POPS SAT EVENING AND EXPANDED THEM NEARLY EVERYWHERE AFTER MIDNIGHT. THE BULK OF OUR RAINFALL AMOUNTS LOOK TO BE FOCUSED FROM MIDNIGHT SATURDAY NIGHT THROUGH NOON ON SUNDAY...WITH ELEVATED THUNDERSTORMS EVEN POSSIBLE AT TIMES LATE SAT NIGHT AND SUNDAY MORNING AS THE COLD FRONT MOVES ACROSS THE AREA. WE KEPT THE MENTION OF THUNDER MAINLY CONFINED WEST OF SPI SAT NIGHT AND SOUTH OF LINCOLN ON SUNDAY MORNING. STRONG SOUTH WINDS WILL ACCOMPANY THE RAIN SHOWERS AND STORMS AS THEY PUSH ACROSS THE AREA. WIND GUSTS OVER 30MPH WILL BE POSSIBLE. BY SUNDAY AFTERNOON THE BEST INSTABILITY WILL HAVE SHIFTED EAST INTO INDIANA AS COLDER AIR BEGINS TO INVADE CENTRAL IL ON NORTHWEST WINDS. DOWNWARD ISENTROPIC MOTIONS AND A DRY PUSH ALOFT WILL HELP TO DIMINISH PRECIP SUNDAY NIGHT FROM NW TO SE. WE KEPT CHANCE POPS IN THE SOUTHEAST HALF...WITH THE POTENTIAL FOR SOME LIGHT SNOW NW OF I-70 AFTER MIDNIGHT. LITTLE IN THE WAY OF SNOW ACCUMULATION IS EXPECTED...AS THE WET AND WARM GROUND MELTS MOST OF ANY SNOWFALL. LONG TERM...MONDAY THROUGH FRIDAY. LINGERING LIGHT SNOW OR RAIN ON MONDAY MORNING SHOULD TAPER TO SPRINKLES BY AFTERNOON. WE KEPT SLIGHT CHANCE POPS IN THE SOUTHEAST...BUT MOST PRECIP SHOULD BE TRACE AMOUNTS BY THAT TIME. THE COLDEST TEMPS OF THE NEXT WEEK SHOULD BE ON MONDAY AND MONDAY NIGHT...WITH HIGHS ONLY AROUND 40 AND LOWS IN THE MID 20S. TEMPS WILL BEGIN A WARMING TREND ON TUESDAY WHICH WILL CONTINUE THROUGH THURSDAY WHEN HIGHS RETURN TO THE 50S. A COOL DOWN IS PROJECTED FOR THURSDAY NIGHT INTO FRIDAY AS THE NEXT COLD FRONT MOVES ACROSS THE AREA EITHER EARLY THURSDAY MORNING /GFS/ OR LATE THURSDAY /ECMWF/. STILL THE COLDER AIR WILL NOT PLUNGE VERY FAR SOUTH INTO OUR COUNTIES...SO THE COOL DOWN WILL BE TEMPORARY. PRECIP CHANCES HAVE BEEN KEPT IN THE SLIGHT CHANCE CATEGORY...AND ONLY ON FRIDAY FOR NOW. SHIMON && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS WICHITA KS
1150 PM CST FRI MAR 8 2013 .AVIATION...06Z TAFS KRSL/KSLN/KHUT/KICT/KCNU EXPECT DETERIORATING AVIATION CONDITIONS OVERNIGHT TO IFR CONDITIONS BETWEEN 06-12Z/SAT AT MOST LOCATIONS AS WIDESPREAD SHOWERS MOVE INTO THE AREA. THIS INITIAL ROUND OF SHOWERS AND EMBEDDED THUNDERSTORMS WILL MOVE INTO AREAS WEST OF INTERSTATE 135 IN THE NEXT COUPLE OF HOURS. WILL SEE ANOTHER ROUND OF SHOWERS AND EMBEDDED THUNDER MOVE IN AROUND 12Z/SAT...WITH WIDESPREAD SHOWERS REMAINING ACROSS THE AREA THROUGH 18Z/SAT. THE DRY LINE ASSOCIATED WITH THIS STORM SYSTEM WILL PUSH INTO THE KRSL/KHUT AND KICT TAF SITES FOR SAT AFTERNOON...WHICH WILL SCOUR OUT THE IFR CEILINGS...AS A MID LEVEL DRY SLOT MOVES ACROSS THE AREA. THIS DRYING OUT OF THE LOW LAYERS...AND SOME POSSIBLE HEATING DUE SOME PEAKS OF SUNSHINE MAY ALSO LEAD TO A RENEWED CHANCE OF THUNDERSTORMS FOR THE KHUT/KICT AND KSLN TAFS...SO WILL INCLUDE A VCTS FOR THIS CHANCE FOR NOW. MAIN LOW PRESSURE AREA ASSOCIATED WITH THIS STORM SYSTEM WILL MOVE ACROSS THE FORECAST AREA FOR SAT EVENING. THIS WILL KEEP THE WINDS OUT OF THE SOUTH FOR THE EVENING HOURS...BUT A STRONG COLD FRONT WILL BEGIN PUSH SOUTH INTO CEN KS BY AROUND 06Z/SUN...WHICH IS BEYOND THIS TAF SET. KETCHAM && .PREV DISCUSSION... /ISSUED 905 PM CST FRI MAR 8 2013/ UPDATE... THE SCATTERED SHOWER CHANCES HAVE BEEN SLOW TO GET GOING ACROSS MOST OF THE FORECAST AREA AT THIS TIME. WITH MAINLY SOME WIDELY SCATTERED SPRITZES/SPRINKLES OR DRIZZLE. LOW LEVEL ISENTROPIC LIFT CONTINUES TO LEAD TO LOTS OF LOW-MID CLOUDS WITH THIS LOW LEVEL SATURATION LEADING TO GRADUALLY LOWER CEILINGS. THINK THE WIDESPREAD SHOWER CHANCES WILL WAIT UNTIL THE INITIAL IMPULSE /THAT IS LEADING TO THE LINE OF CONVECTION IN THE TX PANHANDLE/ BEGINS TO LIFT NORTHEAST INTO SRN KS AFTER MIDNIGHT.. THINK AS THIS IMPULSE LIFTS NORTH...SHOWERS WILL BECOME MORE WIDESPREAD FOR AREAS WEST OF INTERSTATE 135...WHERE BETTER MOISTURE TRANSPORT IS ALREADY IN PLACE. SHORT TERM RUC ALSO SHOWS SOME ELEVATED MUCAPE AROUND 400-600 J/KG MOVING INTO THIS AREA AS WELL...SO THINK SOME RUMBLES OF EMBEDDED THUNDER MAY ALSO MOVE IN AS WELL. CURRENT GRIDS/ZONES LOOK RIGHT ON TRACK...WITH POPS A LITTLE HIGH EARLY ON...BUT THEY LOOK FINE FOR AFTER MIDNIGHT. KETCHAM PREV DISCUSSION... /ISSUED 558 PM CST FRI MAR 8 2013/ AVIATION...00Z TAFS KRSL/KSLN/KHUT/KICT/KCNU MVFR CEILINGS WILL GRADUALLY MOVE INTO MOST OF THE TAF SITES THIS EVENING. EXPECT DETERIORATING AVIATION CONDITIONS OVERNIGHT TO IFR CONDITIONS BETWEEN 06-12Z/SAT AT MOST LOCATIONS AS WIDESPREAD SHOWERS DEVELOP. COULD ALSO SEE SOME EMBEDDED THUNDER AS WELL FOR MOST TAF LOCATIONS BETWEEN 12-18Z/SAT. THE DRY LINE ASSOCIATED WITH THIS STORM SYSTEM WILL PUSH INTO THE KRSL/KHUT AND KICT TAF SITES LATE IN THE TAF PERIOD...WHICH WILL SCOUR OUT THE IFR CEILINGS. THIS DRYING OUT OF THE LOW LAYERS...AND SOME POSSIBLE HEATING DUE SOME PEAKS OF SUNSHINE MAY ALSO LEAD TO A RENEWED CHANCE OF THUNDERSTORMS...SO WILL INCLUDE A VCTS FOR THIS CHANCE FOR THE KHUT/KRSL/KSLN AND KICT TAF SITES. KETCHAM PREV DISCUSSION... /ISSUED 328 PM CST FRI MAR 8 2013/ DISCUSSION... FORECAST HIGHLIGHTS FOCUS AROUND PRECIPITATION CHANCES TONIGHT-SUNDAY...INCLUDING THE POTENTIAL FOR A FEW STRONG SEVERE STORMS SATURDAY AFTERNOON-EVENING...AND SNOW SATURDAY NIGHT-SUNDAY MORNING. IMPRESSIVE LOOKING UPPER LOW WITH QUITE A BIT OF LIGHTNING IS CURRENTLY SPINNING OVER THE DESERT SOUTHWEST. AS THIS STORM SYSTEM APPROACHES THE REGION TONIGHT...ANTICIPATING WIDESPREAD SHOWERS WITH EMBEDDED THUNDERSTORMS TO BE ON THE INCREASE...ESPECIALLY AFTER MIDNIGHT GENERALLY OVER CENTRAL AND SOUTH-CENTRAL KS. GIVEN WEAK INSTABILITY...CANNOT RULE OUT SMALL HAIL WITH THE STRONGEST STORMS. THIS WIDESPREAD SHIELD OF SHOWERS/THUNDERSTORMS WILL GRADUALLY SHIFT EAST ACROSS THE AREA DURING THE DAY SATURDAY...IN ZONE OF STRONG LOW TO MID-LEVEL WARM/MOIST ADVECTION AHEAD OF APPROACHING UPPER WAVE. BY TOMORROW MID-AFTERNOON...BRUNT OF MAIN PRECIPITATION SHIELD SHOULD BE OVER THE EASTERN 1/3 OF KS...WITH SURFACE DRYLINE HANGING BACK WESTWARD OVER CENTRAL/SOUTH-CENTRAL KS...AND COOLING/DRYING ALOFT OVERSPREADING THE WARM SECTOR AHEAD OF APPROACHING SHORTWAVE. IF BREAKS IN OVERCAST CAN DEVELOP ALLOWING SOME HEATING IN WAKE OF MAIN PRECIPITATION SHIELD...THINKING THERE COULD BE A WINDOW OF OPPORTUNITY FROM MID-AFTERNOON THROUGH EARLY EVENING FOR SCATTERED SHALLOW/LOW-TOPPED SURFACE BASED CONVECTION GENERALLY ALONG/WEST OF I-135 CORRIDOR. IF ENOUGH INSTABILITY CAN MATERIALIZE FOR STORMS...LOW-TOPPED SUPERCELLS WILL BE POSSIBLE GIVEN STRONGLY SHEARED ENVIRONMENT...WITH THE POTENTIAL FOR SOME LARGE HAIL. ADDITIONALLY...NAM BUFR SOUNDINGS INDICATE DECENT LOW-LEVEL CAPE OWING TO MID-UPPER 50F DEWPOINTS AND STEEPENING LAPSE RATES...WHICH WOULD SUPPORT THE POTENTIAL FOR AN ISOLATED TORNADO OR TWO. WILL NOT COMPLETELY BITE ONTO THE OMINOUS NAM SOLUTION JUST YET GIVEN AFTERNOON HEATING/INSTABILITY QUESTIONS...BUT DEFINITELY SOMETHING FOR THE NIGHT SHIFT TO EVALUATE FURTHER. BY SATURDAY NIGHT-EARLY SUNDAY...AS UPPER LOW SHIFTS EAST AND MUCH COLDER AIR FILTERS SOUTH...THINKING CENTRAL KS COULD SEE A PERIOD OF LIGHT SNOW. CURRENT INDICATIONS SUGGEST HEAVIEST SNOW WILL REMAIN OFF TO THE NORTH/NORTHWEST...BUT PORTIONS OF CENTRAL KS COULD RECEIVE UP TO 1 INCH OR SO AFTER MIDNIGHT SATURDAY NIGHT THROUGH SUNDAY MORNING. SUNDAY WILL LIKELY BE THE COLDEST DAY OF THE NEXT 7-10 DAYS...WITH HIGHS IN THE 30S-40S AND A STOUT NORTH WIND. GIVEN CURRENT MODEL CONSENSUS...CONFIDENCE IS MODERATE TO HIGH THAT DRY AND WARMING CONDITIONS WILL PREVAIL MONDAY THROUGH NEXT WEEKEND...AS MID/UPPER FLOW FLATTENS OUT SOME AND ATMOSPHERIC HEIGHTS/THICKNESS INCREASES. HIGHS IN THE 50S-60S APPEAR LIKELY. ADK && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 52 62 35 40 / 70 80 40 30 HUTCHINSON 52 63 33 39 / 70 70 40 40 NEWTON 51 61 33 38 / 70 80 50 40 ELDORADO 51 60 35 41 / 70 80 50 30 WINFIELD-KWLD 52 61 37 42 / 70 80 50 20 RUSSELL 52 65 29 38 / 50 50 60 60 GREAT BEND 53 67 30 39 / 50 50 60 60 SALINA 52 63 32 38 / 60 70 50 50 MCPHERSON 52 63 32 38 / 70 70 50 50 COFFEYVILLE 53 61 44 46 / 50 90 70 30 CHANUTE 51 59 42 44 / 50 90 70 40 IOLA 50 59 41 44 / 50 90 70 40 PARSONS-KPPF 52 60 42 45 / 50 90 70 30 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1238 AM EST SAT MAR 9 2013 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 431 PM EST FRI MAR 8 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW DOMINATING NAMERICA. IN THE SRN STREAM...POTENT LOOKING SHORTWAVE HAS MOVED ONSHORE OVER SRN CA WHILE ANOTHER WAVE IS DROPPING S OVER WRN OR/NRN CA. BOTH OF THESE WAVES WILL PLAY A ROLE IN THE WX ACROSS THE GREAT LAKES IN THE COMING DAYS. DOWNSTREAM OF THE WRN TROF...RIDGING IS OVER THE CNTRL CONUS. TO THE N...ONE SHORTWAVE IS TRACKING THRU NRN ONTARIO. ANOTHER WAVE IS DROPPING SE INTO ALBERTA ON THE PERIPHERY OF POLAR VORTEX CENTERED JUST N OF HUDSON BAY. THIS WAVE WILL ALSO PLAY A ROLE IN THE WX OVER THE GREAT LAKES IN THE COMING DAYS. CLOSER TO HOME...LOW CLOUDS HAVE LINGERED OVER THE ERN FCST AREA IN SRLY FLOW OFF LAKE MI. HOWEVER...RECENTLY...ONLY A SMALL AREA OF STRATOCU REMAINS...STREAMING ONSHORE IN SRN SCHOOLCRAFT COUNTY. ELSEWHERE...EARLY MARCH SUNSHINE IS DOING ITS JOB ON THE LOWER ALBEDO FORESTED LAND OF THE U.P. TEMPS HAVE PUSHED INTO THE 40S AT A NUMBER OF OBS SITES OVER WRN UPPER MI. IN THE SHORT TERM...QUIET WX TONIGHT WILL GIVE WAY TO INCREASING PCPN CHANCES SAT UNDER STRENGTHENING WAA REGIME AHEAD OF NRN STREAM WAVE THAT WILL BE MOVING INTO SRN MANITOBA/ND AND SRN STREAM WAVE EMERGING OVER THE SRN HIGH PLAINS. TONIGHT...SRLY FLOW WILL BE ON THE INCREASE AHEAD OF THE AFOREMENTIONED SHORTWAVES. THERE IS THE USUAL CONCERN UNDER SRLY FLOW THAT LOW CLOUDS MAY DEVELOP. IN THIS CASE...HOWEVER...THE NAM AND GFS SHOW DRY AIR ADVECTION TONIGHT AT THE LOW-LEVELS AS TRAJECTORIES STILL HAVE SUFFICIENT COMPONENT EMANATING FROM RETREATING HIGH PRES. SO...LOW CLOUDS MAY NOT REALLY BE AN ISSUE TONIGHT. IF ANY VERY LOW/SHALLOW STRATUS DOES DEVELOP... IT SHOULD ONLY BE IN THE AREAS WITH BEST UPSLOPING OVER CNTRL UPPER MI. OTHERWISE...EXPECT GENERALLY PARTLY CLOUDY SKIES IN THE EVENING...AND THEN AN INCREASE IN HIGH CLOUDS OVERNIGHT. TYPICAL FOR THIS TYPE OF INITIALLY RATHER WEAK SRLY FLOW...EXPECT LOWEST MINS NEAR THE BAY OF GREEN BAY AS ICE COVER ENHANCES COOLING AND STRENGTHENS NOCTURNAL INVERSION IN THAT AREA. LOWS SHOULD BE AROUND 20F THERE. ON SAT...UNDER STRONG WAA AND ISENTROPIC ASCENT (295K SFC)...EXPECT PCPN TO DEVELOP FROM W TO E AS LOW-LEVEL DRY AIR IS EVENTUALLY OVERCOME. TRAJECTORIES SUGGEST THERE WILL BE SOME MAINTENANCE OF THE LOW-LEVEL DRY AIR OVER THE E EVEN AS FORCING AND RESULTING PCPN ALOFT OVERSPREAD THAT AREA. SO...POPS WILL SHOW A GRADIENT FROM CATEGORICAL W TO JUST CHC E LATE. IT`S QUITE POSSIBLE THE E MAY NOT SEE ANY PCPN SAT. AS FOR PTYPE...IT`S A CHALLENGE AS IT ALMOST ALWAYS IS WHEN IT`S NOT COLD ENOUGH FOR JUST SNOW OR WARM ENOUGH FOR JUST RAIN. THERE WILL BE THE USUAL BATTLE BETWEEN STRONG WAA AND THE COOLING IT GENERATES THRU ASCENT AS WELL AS EVAPORATIVE COOLING EARLY ON. BELIEVE THE EVAPORATIVE COOLING EARLY ON WILL LEAD TO PREDOMINANTLY SNOW AS THE PTYPE INITIALLY. THEREAFTER...FCST SOUNDINGS SHOW PROFILE GENERALLY HOVERING AROUND 0C IN THE LOWER LEVELS...FLUCTUATING BASED ON ASCENT/PCPN INTENSITY. MEANWHILE...THE NEAR SFC LAYER MAY RESPOND A LITTLE TO DAYTIME HEATING...PUSHING THE ODDS TOWARD RAIN. AT THIS POINT...WILL INCLUDE SNOW AS THE GENERAL PREVAILING PTYPE IN MOST AREAS WITH A MENTION OF RAIN. INCLUDED FZRA AS WELL WHERE TEMPS ARE AROUND FREEZING. IF THERE IS FZRA...IT SHOULD BE CONFINED TO THE MORNING/EARLY AFTN BEFORE SURFACES RESPOND TO WEAK DAYTIME HEATING. WITH TEMPS PUSHING INTO THE MID 30S... WET/SLUSHY SNOW ACCUMULATIONS WILL BE MINOR...MAYBE AROUND AN INCH. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 431 PM EST FRI MAR 8 2013 SATURDAY NIGHT... THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE EVOLUTION OF THE SYOPTIC PATTERN WITH A PROGRESSIVE PATTERN AND LITTLE PHASING BETWEEN THE NRN STREAM MID LEVEL TROUGH MOVING THROUGH NRN ONTARIO AND THE NRN GREATLAKES AND THE SRN STREAM SHORTWAVE MOVING EAST FROM THE PLAINS. ABUNDANT MOISTURE INFLOW WITH MODERATE TO STRONG 285K-300K ISENTROPIC LIFT AND A PERIOD OF 700-600 MB FGEN SHOULD SUPPORT A BAND OF PCPN THROUGH THE CWA...ESPECIALLY BTWN 00Z-06Z WITH QPF AMOUNTS TO AROUND 0.25 INCH. CONFIDENCE IS ALSO HIGHER THAT A SIGNIFCANT (1C TO 3C) WARM LAYER WILL SPREAD THROUGH MOST OF THE CWA GIVEN STRONG WAA WITH SW 40-45 KT 850 MB WINDS BY 00Z/SUN. GENERALLY UTILIZED NAM/GEM LOW LEVEL THERMAL PROFILE TO DELINEATE PCPN TYPE PATTERN. WITH ENOUGH WARMTH LINGERING FROM DAYTIME HEATING...ANY SFC COLD LAYER WILL BE LESS PRONOUNCED LIMITING POTENTIAL FOR FZRA. SO...MAINLY RA/SN MIX EXPECTED WITH THE GREATEST SNOW CHANCES OVER THE WEST HALF. WITH LOW SLR AOB 10/1...ANY WET SNOWFALL AMOUNTS SHOULD ONLY AMOUNT TO AN INCH OR TWO AT MOST. SUNDAY...THERE WERE GREATER MODEL DIFFERENCES AS THE GFS ALLOWS ANOTHER DEFORMATION BAND OF PCPN TO LIFT INTO UPPER ASSOCIATED WITH THE SRN STREAM SHRTWV. SINCE THE GLOBAL GEM/ECMWF CONTINUE TO SHOW A MORE PROGRESSIVE SOLUTION...THE FCST CONTINUES WITH THE IDEA OF TAPERING OFF POPS/QPF FROM WEST TO EAST WITH MAINLY JUST CHANCE POPS BY AFTERNOON. SOME LAKE ENHANCED SNOW MAY DEVELOP BUT WITH THE SYNOPTIC SCALE UPWARD MOTION AND DEEPER MOISTURE DEPARTING...ANY AMOUNTS SHOULD BE LIGHT. SUN NIGHT INTO MON...850 MB TEMPS DROPPING INTO THE -12C TO -14C ALONG WITH CONTINUED CYCLONIC NRLY FLOW COULD STILL SUPPORT SOME LES. HOWEVER...WITH STRONG 850-700 MB DRYING...ANY AMOUNTS ARE EXPECTED TO BE LIGHT TUE-FRI...MDLS WERE CONSISTENT WITH A WEAK CLIPPER SHORTWAVE AND SFC TROUGH MOVING THROUGH THE UPPER GREAT LAKES MON NIGHT INTO TUE. THE FAVORED ECMWF REMAINED MORE AMPLIFIED WITH THE ERN GREAT LAKES TROUGH BY WED WITH COLDER AIR AVAILABLE FOR SOME NW FLOW LES COMPARED TO THE THE GFS. CONFIDENCE IN DETAILS DROPS OFF BY THU-FRI WITH REGARD TO THE POSITION/STRENGTH OF THE NEXT SHORTWAVE THAT COULD BRING SNOW CHANCES INTO THE REGION. TEMPS SHOULD REMAIN AT OR BELOW SEASONAL AVERAGES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1237 AM EST SAT MAR 9 2013 EXPECT VFR CONDITIONS TO PREVAIL THRU SUNRISE GIVEN DRYNESS OF UPSTREAM AIRMASS TO THE S AND A STEADY S WIND ON THE WRN FLANK OF RETREATING HI PRES OVER SE LWR MI THAT IS LIMITING THE POTENTIAL FOR FOG FORMATION. AN APRCHG LO PRES TROF WL BRING AN INCRSG THREAT W-E OF SOME SN OR MIXED RA/SN DURING THE LATE MRNG/AFTN ON SAT. LINGERING LLVL DRYNESS WL SLOW DOWN THE ONSET OF LOWER CIGS/ VSBY...BUT THESE CONDITIONS SHOULD DVLP WITH PERSISTENT PCPN/ MOISTENING. THE BEST SHOT AT IFR OR EVEN LIFR WX WL BE AT CMX... FARTHER FM DEPARTING LLVL DRY AIR AND WHERE NEAR SFC SE FLOW WL UPSLOPE. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 431 PM EST FRI MAR 8 2013 SOUTHERLY FLOW WILL DOMINATE TONIGHT THRU SAT EVENING AHEAD OF AN APPROACHING LOW PRES TROF. TYPICAL FOR SOUTHERLY FLOW...STRONGEST WINDS WILL BE OVER ERN LAKE SUPERIOR...REACHING UPWARDS OF 30KT SAT AFTN/EVENING. TROF WILL THEN PASS ACROSS LAKE SUPERIOR LATE SAT NIGHT/SUN...BRINGING A SHIFT TO 20-30KT NW WINDS. WINDS WILL THEN SLOWLY SUBSIDE LATE SUN NIGHT/MON...FALLING TO UNDER 15KT FOR MON NIGHT/TUE. MAY SEE A SLIGHT INCREASE IN WINDS WED. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...JLB AVIATION...KC MARINE...JLB
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
348 AM CST SAT MAR 9 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 345 AM CST SAT MAR 9 2013 TWO ROUNDS OF THOUGHT WITH THE STORM. ONE IS FOR A STRONG FGEN FORCED BAND OF SNOW DEVELOPING ACROSS NORTHWEST NEBRASKA TODAY WHICH MOST SOLNS AGREE ON TO VARYING DEGREES. THE SECOND IS FOR ANOTHER STRONG BAND OF SNOW TO DEVELOP ACROSS SOUTH CENTRAL NEBRASKA TONIGHT AS THE FIRST BAND DECAYS. THE GEM REGIONAL AND GFS ARE VERY FAR NORTHWEST WITH THIS BAND SIGNALING A WINTER STORM FOR NCNTL NEB WHILE THE NAM AND ECM ARE SAFELY EAST OF THE FCST AREA. A BLEND OF NAM...GEM AND ECM WERE USED FOR THE LATEST FCST WHICH PROVIDES A WINTER STORM ACROSS THE NORTHWEST AND A WINTER WEATHER ADVISORY ELSEWHERE. HOWEVER THE NAM AND RAP SHOW A VERY STRONG BARRIER JET DEVELOPING THIS EVENING STRETCHING NORTH-SOUTH ALONG AND WEST OF HIGHWAY 83 WHICH COULD EASILY SUPPORT A WINTER STORM IF THE FRONTOGENESIS WAS APPROPRIATELY JUXTAPOSED. THIS IS NOT THE CASE AS THE NAM SHOWS THE FGEN AND HEAVY QPF MOSTLY EAST OF THE FCST AREA. THE RAP MEANWHILE NOSES THE PV1.5 ANOMALY INTO SRN NEB AT 02Z AND DEVELOPS SOME HEAVY SNOW ACROSS SWRN NEB. THIS IS A CONCERN WHICH WILL BE CLOSELY MONITORED. THE STRONG BARRIER JET WILL EASILY SUPPORT 30 MPH WINDS WITH GUSTS TO 45 MPH. IN FACT THE NAM AND RAP SHOW GUSTS TO 60 MPH AT 00Z-03Z...THE HEIGHT OF THE STORM ACROSS SWRN AND NCNTL NEB. SO EVERYONE OUTSIDE OF THE WINTER STORM WARNING HAS BEEN PLACED IN A WINTER WEATHER ADVISORY FOR 3 TO 5 INCHES OF SNOW AND 30 TO 45 MPH WINDS. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 345 AM CST SAT MAR 9 2013 MAJOR SPRING/WINTER STORM WILL BE EXITING SUNDAY MORNING WITH SOME LINGERING LIGHT SNOW ACROSS THE FAR EASTERN COUNTIES. WINDS WILL CONTINUE TO BE GUSTY...AND WILL HIGHLIGHT PATCHY BLOWING SNOW WHERE FALLING SNOW IS EXPECTED. PENDING TOTAL SNOW AND HOW FLUFFY IT IS...MAY NEED TO CONTINUE BLOWING SNOW FURTHER WEST EARLY SUNDAY. STILL QUESTIONING HOW FAR WEST THE HEAVY BAND OF SNOW OVER CENTRAL NEB WILL BE. SUNDAY HIGHS...WITH COLD HIGH PRESSURE BUILDING SOUTH ACROSS THE NORTHERN PLAINS AND MUCH IF NOT ALL OF THE AREA EXPECTED TO SEE A SNOW COVER...SHOULD HOLD CLOSE TO 30 DEGREES. ALTHOUGH THE SUN WILL SPREADING FROM WEST TO EAST...WHICH SHOULD HELP TO START TO MELT ROADWAYS. SUNDAY NIGHT WITH AN ELONGATED HIGH ACROSS THE WESTERN PLAINS...LIGHT WINDS AND MOSTLY CLEAR SKIES ALONG WITH SNOW PACK...TEMPS SHOULD TANK. WIDESPREAD TEENS...WHICH MAY BE CONSERVATIVE. MONDAY INTO MID WEEK RIDGE BUILDS ACROSS THE WEST...WITH A TROUGH TO PUSH ALONG THE NORTHERN STREAM...ACROSS SOUTHERN CANADA AND THE GREAT LAKES. WEAK DISTURBANCE TO MOVE ALONG THE NW FLOW ACROSS THE AREA...HOWEVER MOISTURE LIMITED AND DOUBT ANYTHING WILL REACH THE GROUND AS TIMING IS A LITTLE SLOWER WITH PASSAGE MORE OF A DAYTIME AND THE HEAT OF THE DAY SHOULD BE ENOUGH TO KEEP ANYTHING FROM HITTING THE GROUND. ALSO EARLY IN THE WEEK AS THE SNOW MELTS WILL NEED TO MONITOR FOR OVERNIGHT/MORNING FOG. RIDGE EXPANDS AS THE WEEK CONTINUES...WITH STRONG WAA ALOFT WITH THE WESTERN PART OF THE CWA SEEING DOUBLE DIGIT 850 TEMPS. QUESTION WILL BE HOW LONG CAN THE SNOW REMAIN AND DAMPEN TEMPS. GUIDANCE PUSHES HIGHS INTO THE 50S AND 60S FOR WEDNESDAY AND THURSDAY. AS IS TYPICAL WITH MANY MARCH SNOW STORMS...EXPECT THIS SNOW NOT TO STAY LONG. ALTHOUGH WEST WINDS ON THE LIGHT SIDE...LESS THAN 15 MPH...SHOULD BE ENOUGH TO HELP MIX WITH THE DOWNSLOPE COMPONENT AND HAVE FOLLOWED CLOSER TO GUIDANCE FOR THE LATER HALF OF THE WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1153 PM CST FRI MAR 8 2013 ISOLATED THUNDERSTORMS ARE EXPECTED IN EXTREME SOUTHWEST NEBRASKA NEAR A SURFACE TROUGH AND WARM FRONT. AT THIS TIME...IT APPEARS THAT CELLS THAT HAVE DEVELOPED ALREADY WILL PASS A LITTLE EAST OF LBF AND DISSIPATE BEFORE GOING VERY FAR. WIDESPREAD LIGHT RAIN OR DRIZZLE DEVELOPING NORTH AND WEST OF BBW-LBF IS LIKELY TO SPREAD WESTWARD AS IT MOVES NORTH...AND IT WILL PROBABLY REACH VTN 08-10Z. BY ABOUT 12Z...A BAND OF PRECIPITATION IS EXPECTED TO DEVELOP NORTH AND WEST OF AN ONL-OGA LINE. INITIALLY...IT WILL PROBABLY BE RAIN OR A RAIN/SNOW MIX CHANGING TO SNOW BY ABOUT 14Z AND CONTINUING THROUGH THE DAY SATURDAY. IN CENTRAL THROUGH SOUTHWEST NEBRASKA...SNOW IS NOT EXPECTED BEFORE 00Z. && .LBF WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ006-008-025-026-036-057-058-069. WINTER WEATHER ADVISORY FROM NOON CST TODAY TO 7 AM CDT SUNDAY FOR NEZ007-009-010-027>029-037-038-059-070-071. WINTER STORM WARNING UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ004- 005-022>024-035-056-094. && $$ SHORT TERM...CDC LONG TERM...MASEK AVIATION...SPRINGER
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
156 AM CST SAT MAR 9 2013 .SYNOPSIS... UPPER CLOSED LOW MOVING ON SHORE IN SOUTHERN CALIFORNIA AND WILL CONTINUE ACROSS DESERT SOUTHWEST INTO FOUR CORNERS OVER NIGHT. RIDGE SHARPENING INTO MISSOURI RIVER BASIN WITH CLOSED LOW OVER NORTHWEST ATLANTIC. && .UPDATE... ISSUED AT 156 AM CST SAT MAR 9 2013 GIVEN THE PROJECTED SNOWFALL TOTALS AND STRONG WINDS...IT WOULD BE PRUDENT TO ISSUE A WINTER WEATHER ADVISORY. SO ADDITIONAL COUNTIES HAVE BEEN ADDED TO THE WINTER WEATHER ADVISORY WHICH NOW INCLUDES THE REMAINING PORTION OF NORTH CENTRAL NEBRASKA THAT PREVIOUSLY WAS EXCLUDED FROM A WINTER WEATHER HIGHLIGHT. UPDATE ISSUED AT 103 AM CST SAT MAR 9 2013 A NEW FORECAST IS OUT USING A BLEND OF THE NAM AND GEM. USING AN 8 TO 1 RATIO PRODUCED SIGNIFICANT SNOW ACCUMULATIONS ACROSS THE WARNED AREA AND ELSEWHERE SOUTH AND EAST. ALSO A 50 50 BLEND OF MODEL WINDS AND MAV MET GUIDANCE EASILY PRODUCED WINDS OVER 30 MPH IN THE SNOW SO WINTER WEATHER CONDITIONS SHOULD BE IN FULL SWING TODAY AND TONIGHT. THE RAP13 MODEL SHOWS AN AREA OF STRONG FRONTOGENESIS DEVELOPING ACROSS NW NEB THIS MORNING WHICH APPEARS TO BE IN GOOD AGREEMENT WITH THE NAM AND GEM MODELS. THE RAP THEN SLOWLY PUSHES THE FGEN AND ASSOCIATED SNOW SOUTH AND EAST DURING THE DAY BUT WEAKENS IT AT THE SAME TIME. THUS IT WOULD APPEAR THAT SIGNIFICANT SNOW AND WINTER WEATHER CONDITIONS WILL DEVELOP ACROSS A GOOD PORTION OF THE FCST AREA TODAY AND TONIGHT. UPDATE ISSUED AT 943 PM CST FRI MAR 8 2013 PRECIPITATION IS SLOWER DEVELOPING THAN WE THOUGHT WHEN WE ISSUED THE FORECAST THIS AFTERNOON. THE UPDATED FORECAST REFLECTS THIS IDEA. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ATTENTION IN THE SHORT TERM IS FOCUSED ON THE IMPINGING EARLY SPRING LIKE STORM. A MYRIAD OF WEATHER IS ANTICIPATED...INCLUDING TSTMS AND FREEZING RAIN. WILL UPGRADE THE CURRENT WINTER STORM WATCH TO A WARNING...AND INCLUDE EASTERN CHERRY AND HOOKER COUNTY AS THE HEAVIEST SNOW IS EXPECTED TO BE SLIGHTLY EAST AND SOUTH THAN ORIGINALLY THOUGHT. WILL ALSO ISSUE A WINTER WEATHER ADVISORY FOR THE COUNTIES ADJACENT TO OUR CURRENT WARNING...AS MINOR ICE ACCUMULATIONS AND MODERATE SNOW ACCUMULATIONS ARE EXPECTED. FOR THE REST OF TODAY AND TONIGHT...OUR STORM OF INTEREST IS CURRENTLY MOVING ACROSS SOCAL AND NORTHERN BAJA...TOWARD EASTERN ARIZONA...AND WILL EVENTUALLY PHASE WITH A PROGRESSIVE NORTHERN STREAM TROUGH. SHORT TERM SOLUTIONS ALL AGREE THAT THE PHASED WAVE WILL CROSS THE ROCKIES AND SUPPORT CONTINUED CYCLOGENESIS OVER THE EASTERN HIGH PLAINS OF COLORADO. MEANWHILE STRONG MOISTURE ADVECTION...CURRENTLY ONGOING...WILL CONTINUE TO TARGET THE SOUTHERN AND CENTRAL PLAINS...WITH MOISTURE FOCUSED ACROSS WESTERN NEBRASKA MAINLY IN THE 290-300K SURFACES. THE INCREASING WAA WILL PROVIDE FOR AN OPPORTUNITY OF -SHRA THIS EVENING. BUFR SOUNDINGS DO SUPPORT THE CONTINUED MENTION OF THUNDER AS WELL...AS ELEVATED INSTABILITY INCREASES TO 200-400 J/KG BEFORE MIDNIGHT. WILL TARGET THE HIGHEST THREATS OF STORMS EAST AND SOUTH OF AN IMPERIAL TO NORTH PLATTE TO BARTLETT LINE. AS THE EVENING PROGRESSES INTO THE OVERNIGHT...LARGE SCALE FORCING FOR ASCENT WILL SPREAD EAST WITH THE ENCROACHING WAVE/UPPER JET...SHOWERS WILL BECOME MORE WIDESPREAD ACROSS THE CWA...WITH THE POSSIBILITY OF MIXED OR FREEZING PRECIPITATION OVER OUR NORTHWEST. BUFKIT SOUNDINGS INDICATE THE HIGHEST PROBS OF FREEZING RAIN NEAR KVTN AROUND DAWN...BUT AMOUNTS SHOULD REMAIN LESS THAN A TENTH OF AN INCH. SNOW BEGINS TO COLLECT OVERNIGHT OR JUST BEFORE DAWN ACROSS NORTHWEST NEBRASKA AS MIDLEVEL FRONTOGENETIC BAND TIGHTENS AND DYNAMIC COOLING ALLOWS FOR ACCUMULATIONS. ALL THE SHORT TERM MODELS HAVE CONVERGED ON A SOUTHWEST TO NORTHEAST DEFORMATION BAND...FROM THE SOUTHWESTERN PANHANDLE TO NEAR KVTN. SNOW ACCUMULATIONS OF 6 INCHES OR MORE WILL BE POSSIBLE IN THE WARNED AREA. IN ADDITION...NORTHERLY WINDS AT H85 ARE INDICATED TO BE IN THE 35-40KT RANGE...WE CERTAINLY COULD SEE SOME BLOWING/DRIFTING OF THE SNOW AS THE WIND GUSTS IN EXCESS OF 25 MPH TOMORROW AFTERNOON. THE RAIN/SNOW CHANGE OVER LINE WILL BE FOCUSED ALONG THE ADVANCING COLD FRONT...WHICH IS INDICATED TO CROSS THE MAJORITY OF THE CWA...SAVE FAR SOUTHEASTERN PORTIONS...BY EARLY AFTERNOON TOMORROW...WIDESPREAD SNOW SHOULD PREVAIL FOR MOST LOCATIONS AFTER 21Z. THE INITIAL DEFORMATION ACROSS OUR CWA IS SHOWN TO WEAKEN AND RE-FOCUS ACROSS SOUTH CENTRAL/CENTRAL NEBRASKA LATE AFTERNOON TOMORROW...WITH THE HEAVIEST LATE AFTERNOON ACCUMULATIONS ACROSS EASTERN CUSTER/WHEELER/HOLT COUNTIES. DEPENDING ON THE PROGRESSION OF THE SYSTEM...AN ADDITIONAL WINTER WEATHER ADVISORY MAY BE NEEDED FOR THESE AREAS. WILL WAIT AND SEE HOWEVER...MODEL GUIDANCE WAS TOO FAR WEST WITH THE NORTHERN STREAM PV ANOMALY THIS MORNING AS COMPARED TO THE ACTUAL OBSERVATIONS...A MORE EASTWARD PROGRESSIVE NORTHERN STREAM WOULD FAVOR A FURTHER SOUTHERN AND EASTWARD TREND IN THE SYSTEM...WHICH MAY FOCUS THIS SECONDARY BAND OUTSIDE OUR CWA. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) MODELS HAVE SLIGHT VARIATIONS IN THE LONG TERM. MAIN CONCERN IS DEFORMATION ZONE MOVING SOUTH AND EAST THROUGH THE DAY ON SATURDAY INTO SATURDAY NIGHT. THE ECMWF IS STRONGEST WITH THE ZONE COMING ACROSS AND THEN VARYING DEGREES WITH GFS AND NAM. THE NAM IS FURTHER EAST. HAVE HELD OFF ON ANY HIGH LIGHTS FOR SATURDAY NIGHT WITH WINDS DECREASING AND THEN TRENDS TOWARDS MODELS SHIFTING SYSTEM FURTHER EAST. PRECIPITATION ENDING SUNDAY MORNING TEMPERATURES IN THE 20S AND 30S FOR DAYTIME HIGHS. KEPT COOLER TEMPERATURES OVER SNOW COVER THROUGH MONDAY. POSSIBILITY OF FOG SUNDAY MORNING AND MONDAY NIGHT TUESDAY MORNING WITH MELTING SNOW. COULD BE SOME JET INDUCED SNOW SHOWERS TUESDAY IN FAST NORTHWEST FLOW. UPPER JET CURLS NORTH WEDNESDAY AND PACIFIC AIR MOVES INTO FORECAST AREA. NICE WARMING TREND WITH TEMPERATURES RISING INTO THE UPPER 40S NORTHEAST TO AROUND 60 SOUTHWEST AND WEST. GENERALLY DRY AFTER TUESDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1153 PM CST FRI MAR 8 2013 SOLATED THUNDERSTORMS ARE EXPECTED IN EXTREME SOUTHWEST NEBRASKA NEAR A SURFACE TROUGH AND WARM FRONT. AT THIS TIME...IT APPEARS THAT CELLS THAT HAVE DEVELOPED ALREADY WILL PASS A LITTLE EAST OF LBF AND DISSIPATE BEFORE GOING VERY FAR. WIDESPREAD LIGHT RAIN OR DRIZZLE DEVELOPING NORTH AND WEST OF BBW-LBF IS LIKELY TO SPREAD WESTWARD AS IT MOVES NORTH...AND IT WILL PROBABLY REACH VTN 08-10Z. BY ABOUT 12Z...A BAND OF PRECIPITATION IS EXPECTED TO DEVELOP NORTH AND WEST OF AN ONL-OGA LINE. INITIALLY...IT WILL PROBABLY BE RAIN OR A RAIN/SNOW MIX CHANGING TO SNOW BY ABOUT 14Z AND CONTINUING THROUGH THE DAY SATURDAY. IN CENTRAL THROUGH SOUTHWEST NEBRASKA...SNOW IS NOT EXPECTED BEFORE 00Z. && .LBF WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ006-008-025-026-036-057-058-069. WINTER WEATHER ADVISORY FROM NOON CST TODAY TO 7 AM CDT SUNDAY FOR NEZ007-009-010-027>029-037-038-059-070-071. WINTER STORM WARNING UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ004- 005-022>024-035-056-094. && $$ UPDATE...CDC SYNOPSIS...POWER SHORT TERM...JACOBS LONG TERM...POWER AVIATION...SPRINGER
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
111 AM CST SAT MAR 9 2013 .SYNOPSIS... UPPER CLOSED LOW MOVING ON SHORE IN SOUTHERN CALIFORNIA AND WILL CONTINUE ACROSS DESERT SOUTHWEST INTO FOUR CORNERS OVER NIGHT. RIDGE SHARPENING INTO MISSOURI RIVER BASIN WITH CLOSED LOW OVER NORTHWEST ATLANTIC. && .UPDATE... ISSUED AT 103 AM CST SAT MAR 9 2013 A NEW FORECAST IS OUT USING A BLEND OF THE NAM AND GEM. USING AN 8 TO 1 RATIO PRODUCED SIGNIFICANT SNOW ACCUMULATIONS ACROSS THE WARNED AREA AND ELSEWHERE SOUTH AND EAST. ALSO A 50 50 BLEND OF MODEL WINDS AND MAV MET GUIDANCE EASILY PRODUCED WINDS OVER 30 MPH IN THE SNOW SO WINTER WEATHER CONDITIONS SHOULD BE IN FULL SWING TODAY AND TONIGHT. THE RAP13 MODEL SHOWS AN AREA OF STRONG FRONTOGENESIS DEVELOPING ACROSS NW NEB THIS MORNING WHICH APPEARS TO BE IN GOOD AGREEMENT WITH THE NAM AND GEM MODELS. THE RAP THEN SLOWLY PUSHES THE FGEN AND ASSOCIATED SNOW SOUTH AND EAST DURING THE DAY BUT WEAKENS IT AT THE SAME TIME. THUS IT WOULD APPEAR THAT SIGNIFICANT SNOW AND WINTER WEATHER CONDITIONS WILL DEVELOP ACROSS A GOOD PORTION OF THE FCST AREA TODAY AND TONIGHT. UPDATE ISSUED AT 943 PM CST FRI MAR 8 2013 PRECIPITATION IS SLOWER DEVELOPING THAN WE THOUGHT WHEN WE ISSUED THE FORECAST THIS AFTERNOON. THE UPDATED FORECAST REFLECTS THIS IDEA. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ATTENTION IN THE SHORT TERM IS FOCUSED ON THE IMPINGING EARLY SPRING LIKE STORM. A MYRIAD OF WEATHER IS ANTICIPATED...INCLUDING TSTMS AND FREEZING RAIN. WILL UPGRADE THE CURRENT WINTER STORM WATCH TO A WARNING...AND INCLUDE EASTERN CHERRY AND HOOKER COUNTY AS THE HEAVIEST SNOW IS EXPECTED TO BE SLIGHTLY EAST AND SOUTH THAN ORIGINALLY THOUGHT. WILL ALSO ISSUE A WINTER WEATHER ADVISORY FOR THE COUNTIES ADJACENT TO OUR CURRENT WARNING...AS MINOR ICE ACCUMULATIONS AND MODERATE SNOW ACCUMULATIONS ARE EXPECTED. FOR THE REST OF TODAY AND TONIGHT...OUR STORM OF INTEREST IS CURRENTLY MOVING ACROSS SOCAL AND NORTHERN BAJA...TOWARD EASTERN ARIZONA...AND WILL EVENTUALLY PHASE WITH A PROGRESSIVE NORTHERN STREAM TROUGH. SHORT TERM SOLUTIONS ALL AGREE THAT THE PHASED WAVE WILL CROSS THE ROCKIES AND SUPPORT CONTINUED CYCLOGENESIS OVER THE EASTERN HIGH PLAINS OF COLORADO. MEANWHILE STRONG MOISTURE ADVECTION...CURRENTLY ONGOING...WILL CONTINUE TO TARGET THE SOUTHERN AND CENTRAL PLAINS...WITH MOISTURE FOCUSED ACROSS WESTERN NEBRASKA MAINLY IN THE 290-300K SURFACES. THE INCREASING WAA WILL PROVIDE FOR AN OPPORTUNITY OF -SHRA THIS EVENING. BUFR SOUNDINGS DO SUPPORT THE CONTINUED MENTION OF THUNDER AS WELL...AS ELEVATED INSTABILITY INCREASES TO 200-400 J/KG BEFORE MIDNIGHT. WILL TARGET THE HIGHEST THREATS OF STORMS EAST AND SOUTH OF AN IMPERIAL TO NORTH PLATTE TO BARTLETT LINE. AS THE EVENING PROGRESSES INTO THE OVERNIGHT...LARGE SCALE FORCING FOR ASCENT WILL SPREAD EAST WITH THE ENCROACHING WAVE/UPPER JET...SHOWERS WILL BECOME MORE WIDESPREAD ACROSS THE CWA...WITH THE POSSIBILITY OF MIXED OR FREEZING PRECIPITATION OVER OUR NORTHWEST. BUFKIT SOUNDINGS INDICATE THE HIGHEST PROBS OF FREEZING RAIN NEAR KVTN AROUND DAWN...BUT AMOUNTS SHOULD REMAIN LESS THAN A TENTH OF AN INCH. SNOW BEGINS TO COLLECT OVERNIGHT OR JUST BEFORE DAWN ACROSS NORTHWEST NEBRASKA AS MIDLEVEL FRONTOGENETIC BAND TIGHTENS AND DYNAMIC COOLING ALLOWS FOR ACCUMULATIONS. ALL THE SHORT TERM MODELS HAVE CONVERGED ON A SOUTHWEST TO NORTHEAST DEFORMATION BAND...FROM THE SOUTHWESTERN PANHANDLE TO NEAR KVTN. SNOW ACCUMULATIONS OF 6 INCHES OR MORE WILL BE POSSIBLE IN THE WARNED AREA. IN ADDITION...NORTHERLY WINDS AT H85 ARE INDICATED TO BE IN THE 35-40KT RANGE...WE CERTAINLY COULD SEE SOME BLOWING/DRIFTING OF THE SNOW AS THE WIND GUSTS IN EXCESS OF 25 MPH TOMORROW AFTERNOON. THE RAIN/SNOW CHANGE OVER LINE WILL BE FOCUSED ALONG THE ADVANCING COLD FRONT...WHICH IS INDICATED TO CROSS THE MAJORITY OF THE CWA...SAVE FAR SOUTHEASTERN PORTIONS...BY EARLY AFTERNOON TOMORROW...WIDESPREAD SNOW SHOULD PREVAIL FOR MOST LOCATIONS AFTER 21Z. THE INITIAL DEFORMATION ACROSS OUR CWA IS SHOWN TO WEAKEN AND RE-FOCUS ACROSS SOUTH CENTRAL/CENTRAL NEBRASKA LATE AFTERNOON TOMORROW...WITH THE HEAVIEST LATE AFTERNOON ACCUMULATIONS ACROSS EASTERN CUSTER/WHEELER/HOLT COUNTIES. DEPENDING ON THE PROGRESSION OF THE SYSTEM...AN ADDITIONAL WINTER WEATHER ADVISORY MAY BE NEEDED FOR THESE AREAS. WILL WAIT AND SEE HOWEVER...MODEL GUIDANCE WAS TOO FAR WEST WITH THE NORTHERN STREAM PV ANOMALY THIS MORNING AS COMPARED TO THE ACTUAL OBSERVATIONS...A MORE EASTWARD PROGRESSIVE NORTHERN STREAM WOULD FAVOR A FURTHER SOUTHERN AND EASTWARD TREND IN THE SYSTEM...WHICH MAY FOCUS THIS SECONDARY BAND OUTSIDE OUR CWA. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) MODELS HAVE SLIGHT VARIATIONS IN THE LONG TERM. MAIN CONCERN IS DEFORMATION ZONE MOVING SOUTH AND EAST THROUGH THE DAY ON SATURDAY INTO SATURDAY NIGHT. THE ECMWF IS STRONGEST WITH THE ZONE COMING ACROSS AND THEN VARYING DEGREES WITH GFS AND NAM. THE NAM IS FURTHER EAST. HAVE HELD OFF ON ANY HIGH LIGHTS FOR SATURDAY NIGHT WITH WINDS DECREASING AND THEN TRENDS TOWARDS MODELS SHIFTING SYSTEM FURTHER EAST. PRECIPITATION ENDING SUNDAY MORNING TEMPERATURES IN THE 20S AND 30S FOR DAYTIME HIGHS. KEPT COOLER TEMPERATURES OVER SNOW COVER THROUGH MONDAY. POSSIBILITY OF FOG SUNDAY MORNING AND MONDAY NIGHT TUESDAY MORNING WITH MELTING SNOW. COULD BE SOME JET INDUCED SNOW SHOWERS TUESDAY IN FAST NORTHWEST FLOW. UPPER JET CURLS NORTH WEDNESDAY AND PACIFIC AIR MOVES INTO FORECAST AREA. NICE WARMING TREND WITH TEMPERATURES RISING INTO THE UPPER 40S NORTHEAST TO AROUND 60 SOUTHWEST AND WEST. GENERALLY DRY AFTER TUESDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1153 PM CST FRI MAR 8 2013 SOLATED THUNDERSTORMS ARE EXPECTED IN EXTREME SOUTHWEST NEBRASKA NEAR A SURFACE TROUGH AND WARM FRONT. AT THIS TIME...IT APPEARS THAT CELLS THAT HAVE DEVELOPED ALREADY WILL PASS A LITTLE EAST OF LBF AND DISSIPATE BEFORE GOING VERY FAR. WIDESPREAD LIGHT RAIN OR DRIZZLE DEVELOPING NORTH AND WEST OF BBW-LBF IS LIKELY TO SPREAD WESTWARD AS IT MOVES NORTH...AND IT WILL PROBABLY REACH VTN 08-10Z. BY ABOUT 12Z...A BAND OF PRECIPITATION IS EXPECTED TO DEVELOP NORTH AND WEST OF AN ONL-OGA LINE. INITIALLY...IT WILL PROBABLY BE RAIN OR A RAIN/SNOW MIX CHANGING TO SNOW BY ABOUT 14Z AND CONTINUING THROUGH THE DAY SATURDAY. IN CENTRAL THROUGH SOUTHWEST NEBRASKA...SNOW IS NOT EXPECTED BEFORE 00Z. && .LBF WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ006-008-025-026-036-057-058-069. WINTER STORM WARNING UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ004- 005-022>024-035-056-094. && $$ UPDATE...CDC SYNOPSIS...POWER SHORT TERM...JACOBS LONG TERM...POWER AVIATION...SPRINGER
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
439 AM EST SAT MAR 9 2013 .SYNOPSIS... HIGH PRESSURE WILL PROVIDE CLEAR SKIES AND MODERATING TEMPERATURES THROUGH THE WEEKEND. A COLD FRONT IS EXPECTED TO APPROACH THE REGION MONDAY NIGHT AND BRING THE AREA SCATTERED RAIN SHOWERS BY LATE MONDAY AFTERNOON. TEMPERATURES WILL FALL BACK TO MORE SEASONAL VALUES BY THE MIDDLE OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 330 AM UPDATE... HIPRES WL DOMINATE THE WX TDA. 1030MB SFC HIGH WL BUILD EAST INTO NERN U.S. THIS AFTN. UPR-LVL RIDGING OCCURRING BTWN H5 LOW SPINNING OVR WRN ATLANTIC AND DIGGING INTO 4-CRNRS REGION. THIS HIGH ALOFT WL INFLUENCE THE AREA WX OVR THE WEEKEND AND LEAD TO SUBSIDENCE TDA WITH SUNNY SKIES EXPECTED. H9 TEMPS INCRS FM -2C TO -4C TO +3C ACRS NEPA AND NR 0C OVR THE LK PLAIN. THESE TEMPS WL YIELD HIGHS FM ARND 40F ACRS NRN ZONES TO ARND 50F OVR SRN ZONES. WITH LGT WINDS EXPECTED AND SUNNY SKIES THIS AFTN DO NOT THINK 50S ARE OUT OF THE QUESTION UNDER STRENGTHENING MARCH SUN. THUS FOR MAX TEMP GRIDS HV BUMPED LAV NUMBERS UP BY A DEGREE OR TWO. HIGH CIRRUS WL BEGIN TO OVRSPRD THE REGION FM THE WEST BY 00Z SUNDAY PER LATEST GEM CLD FIELDS. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... 330 AM UPDATE... CIRRUS WL THICKEN UP OVRNGT AS SUN GOES DOWN AND EVENTUALLY LEAD TO PCLDY SKIES BY 12Z SUNDAY. DEPENDING ON HOW THICK CIRRUS WL BE POTENTIAL LOOKS TO EXIST FOR RIDGE/VLY SPLIT IN TEMPS WITH FCST MINS EXPECTED TO BE LWR 20S IN DEEPEST VLYS AND ARND 30 ON RIDGETOPS. LEE-SIDE CYCLOGENESIS OCCURS THIS WEEKEND AS H5 LOW CROSSES FRONT-RANGE. UL SYSTEM WL STEER SFC LOW EVER CLSR TO CWA THO WL STILL RMN FAR ENUF BACK TO OUR WEST ON SUNDAY TO ALLOW HIPRES TO CONT ITS GRIP ON THE REGION. H5 HEIGHTS APPCHG 570 SUN AFTN WL ALLOW TEMPS TO RISE INTO THE 50S AREAWIDE. WITH SW FLOW IN THE BL AND H9 TEMPS APPCHG 7C TO 8C IN THE LK PLAIN SUN AFTN CANNOT RULE OUT UPR 50S IN NRN ZONES THUS HV RAISED HIGHS INTO THE MID-50S FOLLOWING MAV/GMOS NUMBERS. LATEST MODELS ADVERTISING SLOWING DOWN OF SYSTEM AND DELAY PCPN FM ENTERING CWA UNTIL MON AFTN AT THE EARLIEST. 12Z EURO AND 00Z NAM12 INDICATE RAIN WL BE DELAYED UNTIL AFT 00Z TUE THUS HV SLOWED TIMING OF POPS DOWN DRG THE DAY MONDAY WITH ONLY CHC POPS EXPECTED AFT 18Z MONDAY. SFC BNDRY EXPECTED TO RMN BACK TO THE WEST ON MONDAY WITH SRLY FLOW WARMING TEMPS TO NR 50 ONCE AGAIN UNDER CLDY SKIES. MAIN FROPA OCCURS MON NGT/TUE MRNG, THUS HV BUMPED POPS TO 70% DRG THIS TIME WITH RAIN EXPECTED. QPF AMNTS LOOK TO AVG ANYWHERE FM 0.50-0.75 INCHES BY 12Z TUESDAY PER LATEST EURO THO SLIGHTLY HIGHER ON 00Z GFS/NAM. TIMING OF FNT WL PLAY A ROLE IN PTYPE WITH DELAYED FROPA LEADING TO ALL RAIN MON NGT THEREFORE HV BACKED OFF ON RA/SN MIX UNTIL CLOSER TO 09Z. 00Z EURO IS EVEN SLOWER THAN 12Z RUN BY ABOUT 6 HRS. TRENDS INDICATING THAT IMPENDING SYSTEM WL SLOW DOWN EVEN FURTHER AND LATER SHIFTS WL HV TO MONITOR PROGRESS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... 330 AM UPDATE...MINOR TWEEKS TO MED RNG BASED ON LATEST HPC GUIDANCE...BUT OVERALL GIST OF FCST REMAINS UNCHANGED. PREV BLO... 2 PM UPDATE... FOLLOWED HPC GUIDANCE. BEST SHOT FOR PRECIPITATION WILL COME EARLY IN THE PERIOD AS A COLD FRONT MOVES THROUGH MONDAY NIGHT. MAY END AS SOME LIGHT SNOW...ESPECIALLY OVER THE HIGHER TERRAIN EARLY TUESDAY MORNING. PREFERRED THE MORE UNSETTLED HPC GUIDANCE (MORE EURO BASED) THAN THE GFS. THIS SOLUTION SHOWS A TROF...COLDER AIR...AND SNOW SHOWERS THROUGH MID-WEEK. THE GFS IS MORE ZONAL (NORTHWEST FLOW) WITH VARIOUS SHORT WAVES BEFORE A TROF DEVELOPS IN THE EAST BY THE END OF THE WEEK. && .AVIATION /10Z SATURDAY THROUGH WEDNESDAY/... 430 AM UPDATE...AREA OF LOW CLD/STRATUS HAS DVLPD ACRS THE ERN FINGER LAKES. 1000-950 RUC RH APPEARS TO CAPTURE THIS...SUGGESTING THAT THE WRN PERIPHERY COULD BRUSH ITH...AND HAVE ADDED POTNL IFR FOR EARLY THIS MRNG THERE. IF THIS AREA HOLDS TOGETHER AS IT DROPS SWD IT COULD AFFECT BGM TWDS 12Z. PREV BLO... 330 AM UPDATE...ADDED POTNL FOR IFR AT SYR THIS MRNG AS PATCHY STRATUS/FOG HAS DVLPD SE OF LAKE ONTARIO. PREV BLO... VFR WILL PREVAIL THRU 06Z SUN WITH SKC TO BKN250 XPCTD. PATCHY LOW LVL STRATUS COULD DVLP TWDS DAYBREAK OVER PORTIONS OF CNTRL NY BUT PROBS TOO LOW TO INCLUDE IN TAFS. WINDS TDA N TO NW 5-10 KTS...BECMG E TO SE TNGT ARND 5 KTS. .OUTLOOK... SAT NIGHT/SUN...VFR. SUN NGT TO MON...MVFR IN -SHRA. MON NGT TO TUE...MVFR/IFR WITH RAIN CHANGING TO SNOW. WED...MVFR POSSIBLE ESPECIALLY CNY TERMINALS IN SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...PVN NEAR TERM...PVN SHORT TERM...PVN LONG TERM...HEDEN AVIATION...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1036 PM CST FRI MAR 8 2013 .DISCUSSION.../ISSUED AT 1010 PM CST/ PRECIPITATION BEGINNING TO EXPAND ACROSS THE AREA WITHS STRONG MID LEVEL WARM AIR ADVECTION. TEMPERATURES ACROSS THE CWA HAVE GENERALLY RISEN ABOVE FREEZING AT THIS POINT. THE RAP SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT SURFACE TEMPERATURES...AND IT SUGGESTS MOST OF OUR NORTH STAYS JUST ABOVE FREEZING THROUGH THE NIGHT. THUS THINKING MAINLY PLAIN RAIN...ALTHOUGH SOME ICY SPOTS ARE STILL POSSIBLE ALONG THE HIGHWAY 14 CORRIDOR WHERE TEMPERATURES WILL FLIRT WITH THE FREEZING MARK TROUGH THE NIGHT. STARTING TO SEE SOME THUNDER ACROSS NORTHEAST NEBRASKA...AND WITH ELEVATED INSTABILITY MOVING INTO OUR AREA...THINK A FEW LIGHTNING STRIKES WILL BE POSSIBLE...MAINLY ALONG AND SOUTH OF INTERSTATE 90. MODELS COMING INTO BETTER AGREEMENT ON EVOLUTION OF THE SYSTEM TOMORROW...ALTHOUGH UNCERTAINTY STILL EXISTS. NAM...GFS AND SREF ALL SHOWING WHAT COULD BE AN INTENSE MID LEVEL FRONT WEST OF THE JAMES RIVER WITH SOME ELEVATED INSTABILITY AS WELL. THUS THOUGHT IS WE COULD SEE A NARROW INTENSE BAND OF SNOW SOMEWHERE OUT THERE...BEST GUESS AT THIS POINT FROM AROUND GREGORY COUNTY TO BEADLE. AS THE NORTHERN STREAM WAVE PUSHES SOUTHEAST EXPECT DRY AIR AND INCREASING SUBSIDENCE TO ENCROACH FROM THE NORTHWEST DURING THE AFTERNOON AND EVENING. THIS SHOULD ACT TO DISSIPATE THIS BAND AS IT PUSHES OFF SOUTHEAST. HOWEVER AS THE SOUTHERN STREAM WAVE AND PV ANOMALY EJECT INTO THE CENTRAL PLAINS...EXPECT THE BAND TO REFORM FROM CENTRAL NEBRASKA TO NORTHWEST IOWA. THIS WILL ALSO LIKELY BE A SOMEWHAT NARROW CORRIDOR OF MODERATE TO POTENTIALLY HEAVY SNOW FOR SATURDAY NIGHT. SO...CURRENT THOUGHTS ARE FOR LIGHT ICING ACROSS OUR FAR NORTH AND ALSO WEST...GIVING WAY TO 3 TO 6 INCHES OF SNOW WEST OF THE JAMES RIVER IN THAT INITIAL BAND. COULD EVEN SEE ISOLATED HIGHER AMOUNTS...AND FUTURE SHIFTS WILL HAVE TO MONITOR NEW MODEL RUNS AND POSSIBLY CONSIDER UPGRADING A FEW OF THOSE COUNTIES TO WARNINGS. ANOTHER AREA OF 2 TO 6 INCHES SEEMS PROBABLE FROM YANKTON EAST INTO NORTHWEST IOWA WITH THE SECOND BAND THAT FORMS. AGAIN ISOLATED HIGHER AMOUNTS WILL BE POSSIBLE THERE AS WELL. PRETTY CONFIDENT WE WILL NEED AN ADVISORY IN THAT AREA TOMORROW NIGHT...BUT CONFIDENCE WAS TOO LOW FOR A WATCH. WINDS WILL PICK UP SATURDAY NIGHT INTO SUNDAY LIKELY CREATING BLOWING AND DRIFTING ISSUES WITH ANY SNOW THAT FALLS. SO FUTURE SHIFTS WILL ALSO HAVE TO DECIDE IF SNOW AMOUNTS WILL BE HIGH ENOUGH...THAT COMBINED WITH THE WINDS...WOULD WARRANT A WARNING FOR NORTHWEST IOWA. IN BETWEEN THESE TWO BANDS...GENERALLY EXPECTING AN INCH OR TWO OF SNOW. IN SUMMARY...MAINLY RAIN TONIGHT...CHANGING TO SNOW FROM NORTHWEST TO SOUTHEAST TOMORROW INTO TOMORROW EVENING...ROUGHLY AFTER 9 AM HURON...AFTER 1 PM MITCHELL...AFTER 6 PM SIOUX FALLS AND AFTER 9 PM SIOUX CITY. EXPECTING TWO BANDS OF POTENTIALLY UP TO 6 INCHES OF SNOW...ONE WEST OF THE JAMES RIVER AND ONE ACROSS NORTHWEST IOWA...AND LESS IN BETWEEN. WITH THAT SAID...UNCERTAINTY STILL EXISTS IN PLACEMENT OF THESE BANDS...AND WILL DEPEND ON STRENGTH OF BOTH THE NORTHERN AND SOUTHERN STREAM. NEW 0Z GFS AND 0Z GEM HAVE GONE AGAINST THE 12Z EC...0Z NAM AND 21Z SREF...IN THAT THEY ARE SLIGHTLY FURTHER NORTH WITH BOTH BANDS...SUGGESTING A BIT MORE SNOW FOR SIOUX FALLS. THUS STILL A FLUID SITUATION THAT WILL HAVE TO BE MONITORED CLOSELY TONIGHT AND TOMORROW. CURRENT FORECAST FAVORS THE MORE SOUTHERN SREF...NAM AND EC. /CHENARD .PREVIOUS DISCUSSION.../ISSUED AT 253 PM CST/ QUITE A LOT OF CONVECTION IN THE DESERT SOUTHWEST WITH THE COMPACT UPPER LEVEL LOW PRESSURE THAT WILL SOON BE AFFECTING OUR PART OF THE COUNTRY. AS THIS WAVE MOVES INTO THE FOUR CORNERS REGION TONIGHT SOUTHERLY FLOW WILL INCREASE ACROSS THE PLAINS. WITH DECENT LAPSE RATES ALOFT AND VERY STRONG THERMAL/MOISTURE ADVECTION IN THE MID LEVELS SUSPECT RAIN WILL DEVELOP QUICKLY TONIGHT OVER NEBRASKA INTO SOUTH DAKOTA...IOWA AND MINNESOTA. THE LEAD WAVE CAUSING THIS PRECIPITATION WILL SWING A DRY SLOT NORTHWARD LATE TONIGHT INTO TOMORROW MORNING WHICH COULD SHUT DOWN THE SOUTHEAST HALF OF THE CWA FOR AWHILE ON SATURDAY MORNING AND EARLY AFTERNOON AS SATURATION ALOFT IS LOST AND TEMPERATURES LOWER ARE NOT COLD ENOUGH. RAINFALL AMOUNTS TONIGHT IN MANY LOCATIONS LIKELY A QUARTER TO A HALF AN INCH. WILL GO WITH A WINTER WEATHER ADVISORY FROM CHAMBERLAIN TO HURON TO MARSHALL STARTING TONIGHT AND CONTINUING THROUGH SATURDAY AFTERNOON. THE MAIN THREAT WILL BE FREEZING RAIN FROM ABOUT MIDNIGHT THROUGH SUNRISE SATURDAY MORNING WHERE A TENTH TO TWO TENTHS OF AN INCH OF ICING WILL BE POSSIBLE. WILL CONTINUE THROUGH THE AFTERNOON AS SNOW WILL LIKELY DEVELOP...POSSIBLY ACCUMULATING AN INCH OR TWO...AND WINDS WILL SIGNIFICANTLY INCREASE WITH GUSTS TO ABOUT 40 MPH POSSIBLE. ON TOP OF THE PRECIPITATION TONIGHT THE SOUTHERN HALF OF THE CWA...MAINLY SOUTH OF INTERSTATE 90...COULD HEAR A LITTLE THUNDER. AS THIS POTENT WAVE SWINGS ONTO THE PLAINS SATURDAY DYNAMIC COOLING WILL BEGIN TO QUICKLY SHIFT COLDER AIR INTO THE MID AND LOW LEVELS AND TRANSITION THIS COLD AIR FROM WEST TO EAST. FREEZING RAIN WILL TRANSITION TO SNOW IN THE WEST IN THE MORNING THEN CHANGE TO SNOW FROM ABOUT MARSHALL TO SIOUX FALLS TO YANKTON AROUND 600 PM...THEN IN NW IA AROUND 900 PM. THE STRONGEST FORCING LOOKS TO OCCUR FROM ABOUT 0Z THROUGH 9Z IN THE SOUTHERN THIRD OF THE CWA. RIGHT NOW THINKING MAINLY 1 TO 3 INCHES OF SNOW MOST LOCATIONS BUT THE BAND THAT DEVELOPS IN NORTHERN NEBRASKA INTO NORTHWEST IOWA WILL HAVE THE POTENTIAL TO PRODUCE 6 INCHES OR MORE OF SNOW IN A FAIRLY SHORT PERIOD OF TIME. WILL HAVE TO KEEP AN EYE ON THE POTENTIAL FOR BLOWING SNOW ON SATURDAY NIGHT AND SUNDAY MORNING IF MORE SNOW OCCURS THAN EXPECTED AS GUSTS TO AROUND 40 TO 45 MPH IS NOT OUT OF THE QUESTION. SUSPECT WHAT WILL HAPPEN ON SATURDAY IS THE WARM ADVECTION BAND IN THE NORTHERN CWA WILL FALL APART RATHER THAN TRANSITION FROM WEST TO EAST. WHEN THE COLD FRONT ALOFT SWINGS INTO NORTHERN NEBRASKA SATURDAY AFTERNOON A NEW BAND OF PRECIPITATION WILL DEVELOP AND BECOME THE DOMINANT FEATURE. TRIED TO GET THIS POINT ACROSS IN THE GRIDS BUT NOT EASY TO ACCOMPLISH. THIS SECOND BAND WILL BE THE ONE THAT COULD PRODUCE SOME HEAVY SNOW AND ITS LOCATION WILL BE VERY IMPORTANT. MOST OF THE SNOWFALL WILL BE EAST OF THE CWA BY 12Z SUNDAY WITH A COLD AND WINDY SUNDAY EXPECTED. HIGH PRESSURE RIDGE AXIS SLIDES ACROSS THE REGION ON SUNDAY NIGHT...BRINGING DYING WINDS AND DECREASING CLOUDS. THIS IN CONJUNCTION WITH LOW LEVEL COLD AIR ADVECTION WILL RESULT IN A CHILLY NIGHT WITH LOWS IN THE SINGLE DIGITS AND TEENS. THE HIGH MOVES EASTWARD ON MONDAY AS A SURFACE TROUGH APPROACHES FROM THE WEST. THIS WILL PUT MUCH OF OUR AREA IN A RETURNING SOUTHERLY FLOW...AND TEMPERATURES WILL RESPOND IN LIKE...ESPECIALLY IN OUR SOUTHWEST...WITH HIGHS INTO THE MID 40S OVER THAT THAT AREA. BACK TO THE EAST READINGS WILL TAPER DOWN INTO THE 30S...WITH TEMPERATURES A LITTLE TRICKY DEPENDENT ON WHERE FRESH SNOW COVER IS IS IN PLACE WITH SAT/SUN STORM. THE SURFACE TROUGH/BOUNDARY BEGINS TO SLIDE INTO THE WEST LATE IN THE AFTERNOON...THEN SLIDING ACROSS THE AREA ON MONDAY NIGHT. THE ECMWF/GEM WANTING TO SPIT OUT A LITTLE PRECIPITATION WITH THIS IN THE LATE AFTERNOON OR EVENING AS AN UPPER LEVEL SHORTWAVE TRACKS FROM NORTH DAKOTA TO THE LOWER GREAT LAKES REGION OVERNIGHT. AT THE SAME TIME...THE GFS/NAM KEEP IT DRY AND DECIDED TO GO THAT WAY WITH MOISTURE LOOKING TO BE PRETTY LIMITED. IN THE EXTENDED...TUESDAY THROUGH FRIDAY...MODELS IN GOOD AGREEMENT ON KEEPING OUR AREA IN A NORTHWESTERLY UPPER LEVEL FLOW THROUGH THE THE PERIOD. HOWEVER...MODELS ARE IN LESS IN AGREEMENT ON THE MESOSCALE FEATURES...WITH LOOSE CONSENSUS ON POSSIBLE PRECIPITATION SOMETIME IN THE WEDNESDAY AND FRIDAY TIME FRAME AND KEPT SMALL CHANCE POPS IN FOR THOSE PERIODS. TEMPERATURES THROUGH THE EXTENDED LOOK TO REMAIN AT OR ABOVE NORMALS FOR THIS TIME OF YEAR. && .AVIATION.../FOR THE 06Z TAF ISSUANCE/ MVFR CEILINGS WILL CONTINUE TO EXPAND ACROSS THE CWA TONIGHT AND WILL BECOME IFR ACROSS THE ENTIRE AREA BY 12Z SATURDAY. WIDESPREAD RAIN IS ALSO EXPECTED OVERNIGHT MIXING WITH FREEZING RAIN AND CHANGING TO SNOW WEST OF INTERSTATE 29 DURING THE DAY ON SATURDAY AND EAST OF INTERSTATE 29 AFTER 00Z SUNDAY. VISIBILITIES WILL DROP BELOW ONE MILE AT TIMES...ESPECIALLY IN THE SNOW ON SATURDAY. GUSTY NORTH WINDS OF 20 TO 30 KNOTS WILL DEVELOP WEST OF INTERSTATE 29 BY SATURDAY AFTERNOON AND PERSIST THROUGH 06Z SUNDAY. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 6 PM CST SATURDAY FOR SDZ038>040-050-052-053-057-058-063. MN...WINTER WEATHER ADVISORY UNTIL 6 PM CST SATURDAY FOR MNZ071-072. IA...NONE. NE...NONE. && $$
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1012 PM CST FRI MAR 8 2013 .DISCUSSION.../ISSUED AT 1010 PM CST/ PRECIPITATION BEGINNING TO EXPAND ACROSS THE AREA WITHS STRONG MID LEVEL WARM AIR ADVECTION. TEMPERATURES ACROSS THE CWA HAVE GENERALLY RISEN ABOVE FREEZING AT THIS POINT. THE RAP SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT SURFACE TEMPERATURES...AND IT SUGGESTS MOST OF OUR NORTH STAYS JUST ABOVE FREEZING THROUGH THE NIGHT. THUS THINKING MAINLY PLAIN RAIN...ALTHOUGH SOME ICY SPOTS ARE STILL POSSIBLE ALONG THE HIGHWAY 14 CORRIDOR WHERE TEMPERATURES WILL FLIRT WITH THE FREEZING MARK TROUGH THE NIGHT. STARTING TO SEE SOME THUNDER ACROSS NORTHEAST NEBRASKA...AND WITH ELEVATED INSTABILITY MOVING INTO OUR AREA...THINK A FEW LIGHTNING STRIKES WILL BE POSSIBLE...MAINLY ALONG AND SOUTH OF INTERSTATE 90. MODELS COMING INTO BETTER AGREEMENT ON EVOLUTION OF THE SYSTEM TOMORROW...ALTHOUGH UNCERTAINTY STILL EXISTS. NAM...GFS AND SREF ALL SHOWING WHAT COULD BE AN INTENSE MID LEVEL FRONT WEST OF THE JAMES RIVER WITH SOME ELEVATED INSTABILITY AS WELL. THUS THOUGHT IS WE COULD SEE A NARROW INTENSE BAND OF SNOW SOMEWHERE OUT THERE...BEST GUESS AT THIS POINT FROM AROUND GREGORY COUNTY TO BEADLE. AS THE NORTHERN STREAM WAVE PUSHES SOUTHEAST EXPECT DRY AIR AND INCREASING SUBSIDENCE TO ENCROACH FROM THE NORTHWEST DURING THE AFTERNOON AND EVENING. THIS SHOULD ACT TO DISSIPATE THIS BAND AS IT PUSHES OFF SOUTHEAST. HOWEVER AS THE SOUTHERN STREAM WAVE AND PV ANOMALY EJECT INTO THE CENTRAL PLAINS...EXPECT THE BAND TO REFORM FROM CENTRAL NEBRASKA TO NORTHWEST IOWA. THIS WILL ALSO LIKELY BE A SOMEWHAT NARROW CORRIDOR OF MODERATE TO POTENTIALLY HEAVY SNOW FOR SATURDAY NIGHT. SO...CURRENT THOUGHTS ARE FOR LIGHT ICING ACROSS OUR FAR NORTH AND ALSO WEST...GIVING WAY TO 3 TO 6 INCHES OF SNOW WEST OF THE JAMES RIVER IN THAT INITIAL BAND. COULD EVEN SEE ISOLATED HIGHER AMOUNTS...AND FUTURE SHIFTS WILL HAVE TO MONITOR NEW MODEL RUNS AND POSSIBLY CONSIDER UPGRADING A FEW OF THOSE COUNTIES TO WARNINGS. ANOTHER AREA OF 2 TO 6 INCHES SEEMS PROBABLE FROM YANKTON EAST INTO NORTHWEST IOWA WITH THE SECOND BAND THAT FORMS. AGAIN ISOLATED HIGHER AMOUNTS WILL BE POSSIBLE THERE AS WELL. PRETTY CONFIDENT WE WILL NEED AN ADVISORY IN THAT AREA TOMORROW NIGHT...BUT CONFIDENCE WAS TOO LOW FOR A WATCH. WINDS WILL PICK UP SATURDAY NIGHT INTO SUNDAY LIKELY CREATING BLOWING AND DRIFTING ISSUES WITH ANY SNOW THAT FALLS. SO FUTURE SHIFTS WILL ALSO HAVE TO DECIDE IF SNOW AMOUNTS WILL BE HIGH ENOUGH...THAT COMBINED WITH THE WINDS...WOULD WARRANT A WARNING FOR NORTHWEST IOWA. IN BETWEEN THESE TWO BANDS...GENERALLY EXPECTING AN INCH OR TWO OF SNOW. IN SUMMARY...MAINLY RAIN TONIGHT...CHANGING TO SNOW FROM NORTHWEST TO SOUTHEAST TOMORROW INTO TOMORROW EVENING...ROUGHLY AFTER 9 AM HURON...AFTER 1 PM MITCHELL...AFTER 6 PM SIOUX FALLS AND AFTER 9 PM SIOUX CITY. EXPECTING TWO BANDS OF POTENTIALLY UP TO 6 INCHES OF SNOW...ONE WEST OF THE JAMES RIVER AND ONE ACROSS NORTHWEST IOWA...AND LESS IN BETWEEN. WITH THAT SAID...UNCERTAINTY STILL EXISTS IN PLACEMENT OF THESE BANDS...AND WILL DEPEND ON STRENGTH OF BOTH THE NORTHERN AND SOUTHERN STREAM. NEW 0Z GFS AND 0Z GEM HAVE GONE AGAINST THE 12Z EC...0Z NAM AND 21Z SREF...IN THAT THEY ARE SLIGHTLY FURTHER NORTH WITH BOTH BANDS...SUGGESTING A BIT MORE SNOW FOR SIOUX FALLS. THUS STILL A FLUID SITUATION THAT WILL HAVE TO BE MONITORED CLOSELY TONIGHT AND TOMORROW. CURRENT FORECAST FAVORS THE MORE SOUTHERN SREF...NAM AND EC. /CHENARD .PREVIOUS DISCUSSION.../ISSUED AT 253 PM CST/ QUITE A LOT OF CONVECTION IN THE DESERT SOUTHWEST WITH THE COMPACT UPPER LEVEL LOW PRESSURE THAT WILL SOON BE AFFECTING OUR PART OF THE COUNTRY. AS THIS WAVE MOVES INTO THE FOUR CORNERS REGION TONIGHT SOUTHERLY FLOW WILL INCREASE ACROSS THE PLAINS. WITH DECENT LAPSE RATES ALOFT AND VERY STRONG THERMAL/MOISTURE ADVECTION IN THE MID LEVELS SUSPECT RAIN WILL DEVELOP QUICKLY TONIGHT OVER NEBRASKA INTO SOUTH DAKOTA...IOWA AND MINNESOTA. THE LEAD WAVE CAUSING THIS PRECIPITATION WILL SWING A DRY SLOT NORTHWARD LATE TONIGHT INTO TOMORROW MORNING WHICH COULD SHUT DOWN THE SOUTHEAST HALF OF THE CWA FOR AWHILE ON SATURDAY MORNING AND EARLY AFTERNOON AS SATURATION ALOFT IS LOST AND TEMPERATURES LOWER ARE NOT COLD ENOUGH. RAINFALL AMOUNTS TONIGHT IN MANY LOCATIONS LIKELY A QUARTER TO A HALF AN INCH. WILL GO WITH A WINTER WEATHER ADVISORY FROM CHAMBERLAIN TO HURON TO MARSHALL STARTING TONIGHT AND CONTINUING THROUGH SATURDAY AFTERNOON. THE MAIN THREAT WILL BE FREEZING RAIN FROM ABOUT MIDNIGHT THROUGH SUNRISE SATURDAY MORNING WHERE A TENTH TO TWO TENTHS OF AN INCH OF ICING WILL BE POSSIBLE. WILL CONTINUE THROUGH THE AFTERNOON AS SNOW WILL LIKELY DEVELOP...POSSIBLY ACCUMULATING AN INCH OR TWO...AND WINDS WILL SIGNIFICANTLY INCREASE WITH GUSTS TO ABOUT 40 MPH POSSIBLE. ON TOP OF THE PRECIPITATION TONIGHT THE SOUTHERN HALF OF THE CWA...MAINLY SOUTH OF INTERSTATE 90...COULD HEAR A LITTLE THUNDER. AS THIS POTENT WAVE SWINGS ONTO THE PLAINS SATURDAY DYNAMIC COOLING WILL BEGIN TO QUICKLY SHIFT COLDER AIR INTO THE MID AND LOW LEVELS AND TRANSITION THIS COLD AIR FROM WEST TO EAST. FREEZING RAIN WILL TRANSITION TO SNOW IN THE WEST IN THE MORNING THEN CHANGE TO SNOW FROM ABOUT MARSHALL TO SIOUX FALLS TO YANKTON AROUND 600 PM...THEN IN NW IA AROUND 900 PM. THE STRONGEST FORCING LOOKS TO OCCUR FROM ABOUT 0Z THROUGH 9Z IN THE SOUTHERN THIRD OF THE CWA. RIGHT NOW THINKING MAINLY 1 TO 3 INCHES OF SNOW MOST LOCATIONS BUT THE BAND THAT DEVELOPS IN NORTHERN NEBRASKA INTO NORTHWEST IOWA WILL HAVE THE POTENTIAL TO PRODUCE 6 INCHES OR MORE OF SNOW IN A FAIRLY SHORT PERIOD OF TIME. WILL HAVE TO KEEP AN EYE ON THE POTENTIAL FOR BLOWING SNOW ON SATURDAY NIGHT AND SUNDAY MORNING IF MORE SNOW OCCURS THAN EXPECTED AS GUSTS TO AROUND 40 TO 45 MPH IS NOT OUT OF THE QUESTION. SUSPECT WHAT WILL HAPPEN ON SATURDAY IS THE WARM ADVECTION BAND IN THE NORTHERN CWA WILL FALL APART RATHER THAN TRANSITION FROM WEST TO EAST. WHEN THE COLD FRONT ALOFT SWINGS INTO NORTHERN NEBRASKA SATURDAY AFTERNOON A NEW BAND OF PRECIPITATION WILL DEVELOP AND BECOME THE DOMINANT FEATURE. TRIED TO GET THIS POINT ACROSS IN THE GRIDS BUT NOT EASY TO ACCOMPLISH. THIS SECOND BAND WILL BE THE ONE THAT COULD PRODUCE SOME HEAVY SNOW AND ITS LOCATION WILL BE VERY IMPORTANT. MOST OF THE SNOWFALL WILL BE EAST OF THE CWA BY 12Z SUNDAY WITH A COLD AND WINDY SUNDAY EXPECTED. HIGH PRESSURE RIDGE AXIS SLIDES ACROSS THE REGION ON SUNDAY NIGHT...BRINGING DYING WINDS AND DECREASING CLOUDS. THIS IN CONJUNCTION WITH LOW LEVEL COLD AIR ADVECTION WILL RESULT IN A CHILLY NIGHT WITH LOWS IN THE SINGLE DIGITS AND TEENS. THE HIGH MOVES EASTWARD ON MONDAY AS A SURFACE TROUGH APPROACHES FROM THE WEST. THIS WILL PUT MUCH OF OUR AREA IN A RETURNING SOUTHERLY FLOW...AND TEMPERATURES WILL RESPOND IN LIKE...ESPECIALLY IN OUR SOUTHWEST...WITH HIGHS INTO THE MID 40S OVER THAT THAT AREA. BACK TO THE EAST READINGS WILL TAPER DOWN INTO THE 30S...WITH TEMPERATURES A LITTLE TRICKY DEPENDENT ON WHERE FRESH SNOW COVER IS IS IN PLACE WITH SAT/SUN STORM. THE SURFACE TROUGH/BOUNDARY BEGINS TO SLIDE INTO THE WEST LATE IN THE AFTERNOON...THEN SLIDING ACROSS THE AREA ON MONDAY NIGHT. THE ECMWF/GEM WANTING TO SPIT OUT A LITTLE PRECIPITATION WITH THIS IN THE LATE AFTERNOON OR EVENING AS AN UPPER LEVEL SHORTWAVE TRACKS FROM NORTH DAKOTA TO THE LOWER GREAT LAKES REGION OVERNIGHT. AT THE SAME TIME...THE GFS/NAM KEEP IT DRY AND DECIDED TO GO THAT WAY WITH MOISTURE LOOKING TO BE PRETTY LIMITED. IN THE EXTENDED...TUESDAY THROUGH FRIDAY...MODELS IN GOOD AGREEMENT ON KEEPING OUR AREA IN A NORTHWESTERLY UPPER LEVEL FLOW THROUGH THE THE PERIOD. HOWEVER...MODELS ARE IN LESS IN AGREEMENT ON THE MESOSCALE FEATURES...WITH LOOSE CONSENSUS ON POSSIBLE PRECIPITATION SOMETIME IN THE WEDNESDAY AND FRIDAY TIME FRAME AND KEPT SMALL CHANCE POPS IN FOR THOSE PERIODS. TEMPERATURES THROUGH THE EXTENDED LOOK TO REMAIN AT OR ABOVE NORMALS FOR THIS TIME OF YEAR. && .AVIATION.../FOR THE 00Z TAF ISSUANCE/ VFR CEILINGS THIS EVENING WILL GRADUALLY BECOME MVFR BY 06Z AND THEN BECOME IFR 06Z THROUGH 00Z SUNDAY. LIGHT RAIN WILL BECOME WIDESPREAD THIS EVENING WITH FREEZING RAIN POSSIBLE NORTH OF A HON-MWM LINE. ISOLATED THUNDERSTORMS WILL DEVELOP ACROSS NORTHWEST IOWA AND NORTHEAST NEBRASKA AFTER 06Z. BETWEEN 15Z AND 00Z ON SATURDAY...THE RAIN AND FREEZING RAIN WILL GRADUALLY CHANGE TO SNOW WEST OF INTERSTATE 29. VISIBILITIES WILL FREQUENTLY DROP BELOW 3 MILES AS THE RAIN BECOMES WIDESPREAD TONIGHT. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 6 PM CST SATURDAY FOR SDZ038>040- 050-052-053-057-058-063. MN...WINTER WEATHER ADVISORY UNTIL 6 PM CST SATURDAY FOR MNZ071-072. IA...NONE. NE...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
719 AM CST SAT MAR 9 2013 .UPDATE... ISSUED AT 700 AM CST SAT MAR 9 2013 NO NEW DATA WAS AVAILABLE FOR THE QPF FORECAST BUT INDICATIONS ARE THE RAP13 IS VERIFYING ACROSS NRN NEB WITH OVER 1/2 INCH OF ICE AT THE KVTN ASOS. AFTER SLOWING THE EASTERN PROGRESSION OF THE RAIN CHANGE LINE USING THE RUC...NORTH WINDS HAVE INCREASED AND NOW THE RAIN CHANGE LINE IS ROUGHLY FROM CHAPPELL TO THEDFORD TO AINSWORTH. SO THE NAM MAY BE VERIFYING BETTER AND IT WAS USED IN THE NEW FORECAST. A NEW WIND FORECAST USING NAM...GEM...MET AND MAV GUIDANCE PRODUCED GUSTS TO 50 MPH THIS AFTERNOON AND THIS EVENING WHICH IS CONSISTENT WITH THE 60KT BARRIER JET FCST BY BOTH MODELS. THIS STRUCTURE IS FCST TO SET UP ACROSS THE ERN PANHANDLE THIS MORNING AND MOVE SLOWLY EAST THIS AFTN AND TONIGHT ACTING AS A FOCUS FOR SNOW AND STRONG WINDS. THERE IS NO CHANGE TO THE DYNAMICS. STRONG FRONTOGENESIS HANGS UP ACROSS THE NORTHWEST TODAY AND DECAYS WHILE A NEW STRUCTURE DEVELOPS FARTHER EAST THIS EVENING. THE RAP HAS COME IN LINE WITH THE NAM AND ECM DEVELOPING THE NEW SNOW EAST OF THE FCST AREA WHILE THE 06Z GFS HANGS IT UP ACROSS NCNTL AND SWRN NEB...VERY TROUBLING. GIVEN THE VERY STRONG WINDS DEVELOPING...EVEN AN 1/2 INCH PER HOUR SNOWFALL RATE COULD PRODUCE BLIZZARD CONDITIONS. THE SNOW SHOULD GRADUALLY END OVERNIGHT AND SUNDAY MORNING WEST TO EAST WITH CLEARING SKIES TO FOLLOW. WINDY CONDITIONS CONTINUE SUNDAY MORNING IN THE EAST. UPDATE ISSUED AT 527 AM CST SAT MAR 9 2013 THE RAP13 MODEL SHOWS A SLOWER TRANSITION TO SNOW THAN THE NAM. IN FACT THE RAP CARRIES A BROAD AREA OF FREEZING RAIN AHEAD OF THE CHANGEOVER TO SNOW. THIS IS WELL SUPPORTED IN THE MODEL TEMPERATURE FIELDS. SO A NEW FORECAST IS OUT WHICH HEIGHTENS THE THREAT OF FREEZING RAIN. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 345 AM CST SAT MAR 9 2013 TWO ROUNDS OF THOUGHT WITH THE STORM. ONE IS FOR A STRONG FGEN FORCED BAND OF SNOW DEVELOPING ACROSS NORTHWEST NEBRASKA TODAY WHICH MOST SOLNS AGREE ON TO VARYING DEGREES. THE SECOND IS FOR ANOTHER STRONG BAND OF SNOW TO DEVELOP ACROSS SOUTH CENTRAL NEBRASKA TONIGHT AS THE FIRST BAND DECAYS. THE GEM REGIONAL AND GFS ARE VERY FAR NORTHWEST WITH THIS BAND SIGNALING A WINTER STORM FOR NCNTL NEB WHILE THE NAM AND ECM ARE SAFELY EAST OF THE FCST AREA. A BLEND OF NAM...GEM AND ECM WERE USED FOR THE LATEST FCST WHICH PROVIDES A WINTER STORM ACROSS THE NORTHWEST AND A WINTER WEATHER ADVISORY ELSEWHERE. HOWEVER THE NAM AND RAP SHOW A VERY STRONG BARRIER JET DEVELOPING THIS EVENING STRETCHING NORTH-SOUTH ALONG AND WEST OF HIGHWAY 83 WHICH COULD EASILY SUPPORT A WINTER STORM IF THE FRONTOGENESIS WAS APPROPRIATELY JUXTAPOSED. THIS IS NOT THE CASE AS THE NAM SHOWS THE FGEN AND HEAVY QPF MOSTLY EAST OF THE FCST AREA. THE RAP MEANWHILE NOSES THE PV1.5 ANOMALY INTO SRN NEB AT 02Z AND DEVELOPS SOME HEAVY SNOW ACROSS SWRN NEB. THIS IS A CONCERN WHICH WILL BE CLOSELY MONITORED. THE STRONG BARRIER JET WILL EASILY SUPPORT 30 MPH WINDS WITH GUSTS TO 45 MPH. IN FACT THE NAM AND RAP SHOW GUSTS TO 60 MPH AT 00Z-03Z...THE HEIGHT OF THE STORM ACROSS SWRN AND NCNTL NEB. SO EVERYONE OUTSIDE OF THE WINTER STORM WARNING HAS BEEN PLACED IN A WINTER WEATHER ADVISORY FOR 3 TO 5 INCHES OF SNOW AND 30 TO 45 MPH WINDS. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 345 AM CST SAT MAR 9 2013 MAJOR SPRING/WINTER STORM WILL BE EXITING SUNDAY MORNING WITH SOME LINGERING LIGHT SNOW ACROSS THE FAR EASTERN COUNTIES. WINDS WILL CONTINUE TO BE GUSTY...AND WILL HIGHLIGHT PATCHY BLOWING SNOW WHERE FALLING SNOW IS EXPECTED. PENDING TOTAL SNOW AND HOW FLUFFY IT IS...MAY NEED TO CONTINUE BLOWING SNOW FURTHER WEST EARLY SUNDAY. STILL QUESTIONING HOW FAR WEST THE HEAVY BAND OF SNOW OVER CENTRAL NEB WILL BE. SUNDAY HIGHS...WITH COLD HIGH PRESSURE BUILDING SOUTH ACROSS THE NORTHERN PLAINS AND MUCH IF NOT ALL OF THE AREA EXPECTED TO SEE A SNOW COVER...SHOULD HOLD CLOSE TO 30 DEGREES. ALTHOUGH THE SUN WILL SPREADING FROM WEST TO EAST...WHICH SHOULD HELP TO START TO MELT ROADWAYS. SUNDAY NIGHT WITH AN ELONGATED HIGH ACROSS THE WESTERN PLAINS...LIGHT WINDS AND MOSTLY CLEAR SKIES ALONG WITH SNOW PACK...TEMPS SHOULD TANK. WIDESPREAD TEENS...WHICH MAY BE CONSERVATIVE. MONDAY INTO MID WEEK RIDGE BUILDS ACROSS THE WEST...WITH A TROUGH TO PUSH ALONG THE NORTHERN STREAM...ACROSS SOUTHERN CANADA AND THE GREAT LAKES. WEAK DISTURBANCE TO MOVE ALONG THE NW FLOW ACROSS THE AREA...HOWEVER MOISTURE LIMITED AND DOUBT ANYTHING WILL REACH THE GROUND AS TIMING IS A LITTLE SLOWER WITH PASSAGE MORE OF A DAYTIME AND THE HEAT OF THE DAY SHOULD BE ENOUGH TO KEEP ANYTHING FROM HITTING THE GROUND. ALSO EARLY IN THE WEEK AS THE SNOW MELTS WILL NEED TO MONITOR FOR OVERNIGHT/MORNING FOG. RIDGE EXPANDS AS THE WEEK CONTINUES...WITH STRONG WAA ALOFT WITH THE WESTERN PART OF THE CWA SEEING DOUBLE DIGIT 850 TEMPS. QUESTION WILL BE HOW LONG CAN THE SNOW REMAIN AND DAMPEN TEMPS. GUIDANCE PUSHES HIGHS INTO THE 50S AND 60S FOR WEDNESDAY AND THURSDAY. AS IS TYPICAL WITH MANY MARCH SNOW STORMS...EXPECT THIS SNOW NOT TO STAY LONG. ALTHOUGH WEST WINDS ON THE LIGHT SIDE...LESS THAN 15 MPH...SHOULD BE ENOUGH TO HELP MIX WITH THE DOWNSLOPE COMPONENT AND HAVE FOLLOWED CLOSER TO GUIDANCE FOR THE LATER HALF OF THE WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 537 AM CST SAT MAR 9 2013 EXPECTING IFR/LIFR TO CONTINUE THROUGH 03Z THIS EVENING IN SNOW...BLOWING SNOW...FOG...RAIN AND FREEZING RAIN. THEREAFTER AN IMPROVEMENT TO MVFR/VFR SHOULD COMMENCE FROM NORTHWEST TO SOUTHEAST. WINDS TODAY WILL INCREASE TO 36030G40KT AND DIMINISH LATE THIS EVENING TO 34020G30KT BY 12Z SUNDAY. && .LBF WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ006-008-025-026-036-057-058-069. WINTER WEATHER ADVISORY FROM NOON CST TODAY TO 7 AM CDT SUNDAY FOR NEZ007-009-010-027>029-037-038-059-070-071. WINTER STORM WARNING UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ004- 005-022>024-035-056-094. && $$ UPDATE...CDC SHORT TERM...CDC LONG TERM...MASEK AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
540 AM CST SAT MAR 9 2013 .UPDATE... ISSUED AT 527 AM CST SAT MAR 9 2013 THE RAP13 MODEL SHOWS A SLOWER TRANSITION TO SNOW THAN THE NAM. IN FACT THE RAP CARRIES A BROAD AREA OF FREEZING RAIN AHEAD OF THE CHANGEOVER TO SNOW. THIS IS WELL SUPPORTED IN THE MODEL TEMPERATURE FIELDS. SO A NEW FORECAST IS OUT WHICH HEIGHTENS THE THREAT OF FREEZING RAIN. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 345 AM CST SAT MAR 9 2013 TWO ROUNDS OF THOUGHT WITH THE STORM. ONE IS FOR A STRONG FGEN FORCED BAND OF SNOW DEVELOPING ACROSS NORTHWEST NEBRASKA TODAY WHICH MOST SOLNS AGREE ON TO VARYING DEGREES. THE SECOND IS FOR ANOTHER STRONG BAND OF SNOW TO DEVELOP ACROSS SOUTH CENTRAL NEBRASKA TONIGHT AS THE FIRST BAND DECAYS. THE GEM REGIONAL AND GFS ARE VERY FAR NORTHWEST WITH THIS BAND SIGNALING A WINTER STORM FOR NCNTL NEB WHILE THE NAM AND ECM ARE SAFELY EAST OF THE FCST AREA. A BLEND OF NAM...GEM AND ECM WERE USED FOR THE LATEST FCST WHICH PROVIDES A WINTER STORM ACROSS THE NORTHWEST AND A WINTER WEATHER ADVISORY ELSEWHERE. HOWEVER THE NAM AND RAP SHOW A VERY STRONG BARRIER JET DEVELOPING THIS EVENING STRETCHING NORTH-SOUTH ALONG AND WEST OF HIGHWAY 83 WHICH COULD EASILY SUPPORT A WINTER STORM IF THE FRONTOGENESIS WAS APPROPRIATELY JUXTAPOSED. THIS IS NOT THE CASE AS THE NAM SHOWS THE FGEN AND HEAVY QPF MOSTLY EAST OF THE FCST AREA. THE RAP MEANWHILE NOSES THE PV1.5 ANOMALY INTO SRN NEB AT 02Z AND DEVELOPS SOME HEAVY SNOW ACROSS SWRN NEB. THIS IS A CONCERN WHICH WILL BE CLOSELY MONITORED. THE STRONG BARRIER JET WILL EASILY SUPPORT 30 MPH WINDS WITH GUSTS TO 45 MPH. IN FACT THE NAM AND RAP SHOW GUSTS TO 60 MPH AT 00Z-03Z...THE HEIGHT OF THE STORM ACROSS SWRN AND NCNTL NEB. SO EVERYONE OUTSIDE OF THE WINTER STORM WARNING HAS BEEN PLACED IN A WINTER WEATHER ADVISORY FOR 3 TO 5 INCHES OF SNOW AND 30 TO 45 MPH WINDS. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 345 AM CST SAT MAR 9 2013 MAJOR SPRING/WINTER STORM WILL BE EXITING SUNDAY MORNING WITH SOME LINGERING LIGHT SNOW ACROSS THE FAR EASTERN COUNTIES. WINDS WILL CONTINUE TO BE GUSTY...AND WILL HIGHLIGHT PATCHY BLOWING SNOW WHERE FALLING SNOW IS EXPECTED. PENDING TOTAL SNOW AND HOW FLUFFY IT IS...MAY NEED TO CONTINUE BLOWING SNOW FURTHER WEST EARLY SUNDAY. STILL QUESTIONING HOW FAR WEST THE HEAVY BAND OF SNOW OVER CENTRAL NEB WILL BE. SUNDAY HIGHS...WITH COLD HIGH PRESSURE BUILDING SOUTH ACROSS THE NORTHERN PLAINS AND MUCH IF NOT ALL OF THE AREA EXPECTED TO SEE A SNOW COVER...SHOULD HOLD CLOSE TO 30 DEGREES. ALTHOUGH THE SUN WILL SPREADING FROM WEST TO EAST...WHICH SHOULD HELP TO START TO MELT ROADWAYS. SUNDAY NIGHT WITH AN ELONGATED HIGH ACROSS THE WESTERN PLAINS...LIGHT WINDS AND MOSTLY CLEAR SKIES ALONG WITH SNOW PACK...TEMPS SHOULD TANK. WIDESPREAD TEENS...WHICH MAY BE CONSERVATIVE. MONDAY INTO MID WEEK RIDGE BUILDS ACROSS THE WEST...WITH A TROUGH TO PUSH ALONG THE NORTHERN STREAM...ACROSS SOUTHERN CANADA AND THE GREAT LAKES. WEAK DISTURBANCE TO MOVE ALONG THE NW FLOW ACROSS THE AREA...HOWEVER MOISTURE LIMITED AND DOUBT ANYTHING WILL REACH THE GROUND AS TIMING IS A LITTLE SLOWER WITH PASSAGE MORE OF A DAYTIME AND THE HEAT OF THE DAY SHOULD BE ENOUGH TO KEEP ANYTHING FROM HITTING THE GROUND. ALSO EARLY IN THE WEEK AS THE SNOW MELTS WILL NEED TO MONITOR FOR OVERNIGHT/MORNING FOG. RIDGE EXPANDS AS THE WEEK CONTINUES...WITH STRONG WAA ALOFT WITH THE WESTERN PART OF THE CWA SEEING DOUBLE DIGIT 850 TEMPS. QUESTION WILL BE HOW LONG CAN THE SNOW REMAIN AND DAMPEN TEMPS. GUIDANCE PUSHES HIGHS INTO THE 50S AND 60S FOR WEDNESDAY AND THURSDAY. AS IS TYPICAL WITH MANY MARCH SNOW STORMS...EXPECT THIS SNOW NOT TO STAY LONG. ALTHOUGH WEST WINDS ON THE LIGHT SIDE...LESS THAN 15 MPH...SHOULD BE ENOUGH TO HELP MIX WITH THE DOWNSLOPE COMPONENT AND HAVE FOLLOWED CLOSER TO GUIDANCE FOR THE LATER HALF OF THE WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 537 AM CST SAT MAR 9 2013 EXPECTING IFR/LIFR TO CONTINUE THROUGH 03Z THIS EVENING IN SNOW...BLOWING SNOW...FOG...RAIN AND FREEZING RAIN. THEREAFTER AN IMPROVEMENT TO MVFR/VFR SHOULD COMMENCE FROM NORTHWEST TO SOUTHEAST. WINDS TODAY WILL INCREASE TO 36030G40KT AND DIMINISH LATE THIS EVENING TO 34020G30KT BY 12Z SUNDAY. && .LBF WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ006-008-025-026-036-057-058-069. WINTER WEATHER ADVISORY FROM NOON CST TODAY TO 7 AM CDT SUNDAY FOR NEZ007-009-010-027>029-037-038-059-070-071. WINTER STORM WARNING UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ004- 005-022>024-035-056-094. && $$ UPDATE...CDC SHORT TERM...CDC LONG TERM...MASEK AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
528 AM CST SAT MAR 9 2013 .UPDATE... ISSUED AT 527 AM CST SAT MAR 9 2013 THE RAP13 MODEL SHOWS A SLOWER TRANSITION TO SNOW THAN THE NAM. IN FACT THE RAP CARRIES A BROAD AREA OF FREEZING RAIN AHEAD OF THE CHANGEOVER TO SNOW. THIS IS WELL SUPPORTED IN THE MODEL TEMPERATURE FIELDS. SO A NEW FORECAST IS OUT WHICH HEIGHTENS THE THREAT OF FREEZING RAIN. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 345 AM CST SAT MAR 9 2013 TWO ROUNDS OF THOUGHT WITH THE STORM. ONE IS FOR A STRONG FGEN FORCED BAND OF SNOW DEVELOPING ACROSS NORTHWEST NEBRASKA TODAY WHICH MOST SOLNS AGREE ON TO VARYING DEGREES. THE SECOND IS FOR ANOTHER STRONG BAND OF SNOW TO DEVELOP ACROSS SOUTH CENTRAL NEBRASKA TONIGHT AS THE FIRST BAND DECAYS. THE GEM REGIONAL AND GFS ARE VERY FAR NORTHWEST WITH THIS BAND SIGNALING A WINTER STORM FOR NCNTL NEB WHILE THE NAM AND ECM ARE SAFELY EAST OF THE FCST AREA. A BLEND OF NAM...GEM AND ECM WERE USED FOR THE LATEST FCST WHICH PROVIDES A WINTER STORM ACROSS THE NORTHWEST AND A WINTER WEATHER ADVISORY ELSEWHERE. HOWEVER THE NAM AND RAP SHOW A VERY STRONG BARRIER JET DEVELOPING THIS EVENING STRETCHING NORTH-SOUTH ALONG AND WEST OF HIGHWAY 83 WHICH COULD EASILY SUPPORT A WINTER STORM IF THE FRONTOGENESIS WAS APPROPRIATELY JUXTAPOSED. THIS IS NOT THE CASE AS THE NAM SHOWS THE FGEN AND HEAVY QPF MOSTLY EAST OF THE FCST AREA. THE RAP MEANWHILE NOSES THE PV1.5 ANOMALY INTO SRN NEB AT 02Z AND DEVELOPS SOME HEAVY SNOW ACROSS SWRN NEB. THIS IS A CONCERN WHICH WILL BE CLOSELY MONITORED. THE STRONG BARRIER JET WILL EASILY SUPPORT 30 MPH WINDS WITH GUSTS TO 45 MPH. IN FACT THE NAM AND RAP SHOW GUSTS TO 60 MPH AT 00Z-03Z...THE HEIGHT OF THE STORM ACROSS SWRN AND NCNTL NEB. SO EVERYONE OUTSIDE OF THE WINTER STORM WARNING HAS BEEN PLACED IN A WINTER WEATHER ADVISORY FOR 3 TO 5 INCHES OF SNOW AND 30 TO 45 MPH WINDS. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 345 AM CST SAT MAR 9 2013 MAJOR SPRING/WINTER STORM WILL BE EXITING SUNDAY MORNING WITH SOME LINGERING LIGHT SNOW ACROSS THE FAR EASTERN COUNTIES. WINDS WILL CONTINUE TO BE GUSTY...AND WILL HIGHLIGHT PATCHY BLOWING SNOW WHERE FALLING SNOW IS EXPECTED. PENDING TOTAL SNOW AND HOW FLUFFY IT IS...MAY NEED TO CONTINUE BLOWING SNOW FURTHER WEST EARLY SUNDAY. STILL QUESTIONING HOW FAR WEST THE HEAVY BAND OF SNOW OVER CENTRAL NEB WILL BE. SUNDAY HIGHS...WITH COLD HIGH PRESSURE BUILDING SOUTH ACROSS THE NORTHERN PLAINS AND MUCH IF NOT ALL OF THE AREA EXPECTED TO SEE A SNOW COVER...SHOULD HOLD CLOSE TO 30 DEGREES. ALTHOUGH THE SUN WILL SPREADING FROM WEST TO EAST...WHICH SHOULD HELP TO START TO MELT ROADWAYS. SUNDAY NIGHT WITH AN ELONGATED HIGH ACROSS THE WESTERN PLAINS...LIGHT WINDS AND MOSTLY CLEAR SKIES ALONG WITH SNOW PACK...TEMPS SHOULD TANK. WIDESPREAD TEENS...WHICH MAY BE CONSERVATIVE. MONDAY INTO MID WEEK RIDGE BUILDS ACROSS THE WEST...WITH A TROUGH TO PUSH ALONG THE NORTHERN STREAM...ACROSS SOUTHERN CANADA AND THE GREAT LAKES. WEAK DISTURBANCE TO MOVE ALONG THE NW FLOW ACROSS THE AREA...HOWEVER MOISTURE LIMITED AND DOUBT ANYTHING WILL REACH THE GROUND AS TIMING IS A LITTLE SLOWER WITH PASSAGE MORE OF A DAYTIME AND THE HEAT OF THE DAY SHOULD BE ENOUGH TO KEEP ANYTHING FROM HITTING THE GROUND. ALSO EARLY IN THE WEEK AS THE SNOW MELTS WILL NEED TO MONITOR FOR OVERNIGHT/MORNING FOG. RIDGE EXPANDS AS THE WEEK CONTINUES...WITH STRONG WAA ALOFT WITH THE WESTERN PART OF THE CWA SEEING DOUBLE DIGIT 850 TEMPS. QUESTION WILL BE HOW LONG CAN THE SNOW REMAIN AND DAMPEN TEMPS. GUIDANCE PUSHES HIGHS INTO THE 50S AND 60S FOR WEDNESDAY AND THURSDAY. AS IS TYPICAL WITH MANY MARCH SNOW STORMS...EXPECT THIS SNOW NOT TO STAY LONG. ALTHOUGH WEST WINDS ON THE LIGHT SIDE...LESS THAN 15 MPH...SHOULD BE ENOUGH TO HELP MIX WITH THE DOWNSLOPE COMPONENT AND HAVE FOLLOWED CLOSER TO GUIDANCE FOR THE LATER HALF OF THE WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1153 PM CST FRI MAR 8 2013 ISOLATED THUNDERSTORMS ARE EXPECTED IN EXTREME SOUTHWEST NEBRASKA NEAR A SURFACE TROUGH AND WARM FRONT. AT THIS TIME...IT APPEARS THAT CELLS THAT HAVE DEVELOPED ALREADY WILL PASS A LITTLE EAST OF LBF AND DISSIPATE BEFORE GOING VERY FAR. WIDESPREAD LIGHT RAIN OR DRIZZLE DEVELOPING NORTH AND WEST OF BBW-LBF IS LIKELY TO SPREAD WESTWARD AS IT MOVES NORTH...AND IT WILL PROBABLY REACH VTN 08-10Z. BY ABOUT 12Z...A BAND OF PRECIPITATION IS EXPECTED TO DEVELOP NORTH AND WEST OF AN ONL-OGA LINE. INITIALLY...IT WILL PROBABLY BE RAIN OR A RAIN/SNOW MIX CHANGING TO SNOW BY ABOUT 14Z AND CONTINUING THROUGH THE DAY SATURDAY. IN CENTRAL THROUGH SOUTHWEST NEBRASKA...SNOW IS NOT EXPECTED BEFORE 00Z. && .LBF WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ006-008-025-026-036-057-058-069. WINTER WEATHER ADVISORY FROM NOON CST TODAY TO 7 AM CDT SUNDAY FOR NEZ007-009-010-027>029-037-038-059-070-071. WINTER STORM WARNING UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ004- 005-022>024-035-056-094. && $$ UPDATE...CDC SHORT TERM...CDC LONG TERM...MASEK AVIATION...SPRINGER
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
602 AM EST SAT MAR 9 2013 .SYNOPSIS... HIGH PRESSURE WILL PROVIDE CLEAR SKIES AND MODERATING TEMPERATURES THROUGH THE WEEKEND. A COLD FRONT IS EXPECTED TO APPROACH THE REGION MONDAY NIGHT AND BRING THE AREA SCATTERED RAIN SHOWERS BY LATE MONDAY AFTERNOON. TEMPERATURES WILL FALL BACK TO MORE SEASONAL VALUES BY THE MIDDLE OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 6 AM UPDATE... QUICK UPDATE TO ADD IN LOW STRATUS OVR FINGER LKS AS THAT HAS DEVELOPED SINCE 08Z UNDER CALM WINDS AND LWRNG DWPT DEPRESSIONS. EXPECT BY THE TIME MIXING STARTS LOW CLOUDS SHUD SCATTER OUT AND LEAVE A SUNNY DAY ON TAP. PREV DISCO BLO... 330 AM UPDATE... HIPRES WL DOMINATE THE WX TDA. 1030MB SFC HIGH WL BUILD EAST INTO NERN U.S. THIS AFTN. UPR-LVL RIDGING OCCURRING BTWN H5 LOW SPINNING OVR WRN ATLANTIC AND DIGGING INTO 4-CRNRS REGION. THIS HIGH ALOFT WL INFLUENCE THE AREA WX OVR THE WEEKEND AND LEAD TO SUBSIDENCE TDA WITH SUNNY SKIES EXPECTED. H9 TEMPS INCRS FM -2C TO -4C TO +3C ACRS NEPA AND NR 0C OVR THE LK PLAIN. THESE TEMPS WL YIELD HIGHS FM ARND 40F ACRS NRN ZONES TO ARND 50F OVR SRN ZONES. WITH LGT WINDS EXPECTED AND SUNNY SKIES THIS AFTN DO NOT THINK 50S ARE OUT OF THE QUESTION UNDER STRENGTHENING MARCH SUN. THUS FOR MAX TEMP GRIDS HV BUMPED LAV NUMBERS UP BY A DEGREE OR TWO. HIGH CIRRUS WL BEGIN TO OVRSPRD THE REGION FM THE WEST BY 00Z SUNDAY PER LATEST GEM CLD FIELDS. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... 330 AM UPDATE... CIRRUS WL THICKEN UP OVRNGT AS SUN GOES DOWN AND EVENTUALLY LEAD TO PCLDY SKIES BY 12Z SUNDAY. DEPENDING ON HOW THICK CIRRUS WL BE POTENTIAL LOOKS TO EXIST FOR RIDGE/VLY SPLIT IN TEMPS WITH FCST MINS EXPECTED TO BE LWR 20S IN DEEPEST VLYS AND ARND 30 ON RIDGETOPS. LEE-SIDE CYCLOGENESIS OCCURS THIS WEEKEND AS H5 LOW CROSSES FRONT-RANGE. UL SYSTEM WL STEER SFC LOW EVER CLSR TO CWA THO WL STILL RMN FAR ENUF BACK TO OUR WEST ON SUNDAY TO ALLOW HIPRES TO CONT ITS GRIP ON THE REGION. H5 HEIGHTS APPCHG 570 SUN AFTN WL ALLOW TEMPS TO RISE INTO THE 50S AREAWIDE. WITH SW FLOW IN THE BL AND H9 TEMPS APPCHG 7C TO 8C IN THE LK PLAIN SUN AFTN CANNOT RULE OUT UPR 50S IN NRN ZONES THUS HV RAISED HIGHS INTO THE MID-50S FOLLOWING MAV/GMOS NUMBERS. LATEST MODELS ADVERTISING SLOWING DOWN OF SYSTEM AND DELAY PCPN FM ENTERING CWA UNTIL MON AFTN AT THE EARLIEST. 12Z EURO AND 00Z NAM12 INDICATE RAIN WL BE DELAYED UNTIL AFT 00Z TUE THUS HV SLOWED TIMING OF POPS DOWN DRG THE DAY MONDAY WITH ONLY CHC POPS EXPECTED AFT 18Z MONDAY. SFC BNDRY EXPECTED TO RMN BACK TO THE WEST ON MONDAY WITH SRLY FLOW WARMING TEMPS TO NR 50 ONCE AGAIN UNDER CLDY SKIES. MAIN FROPA OCCURS MON NGT/TUE MRNG, THUS HV BUMPED POPS TO 70% DRG THIS TIME WITH RAIN EXPECTED. QPF AMNTS LOOK TO AVG ANYWHERE FM 0.50-0.75 INCHES BY 12Z TUESDAY PER LATEST EURO THO SLIGHTLY HIGHER ON 00Z GFS/NAM. TIMING OF FNT WL PLAY A ROLE IN PTYPE WITH DELAYED FROPA LEADING TO ALL RAIN MON NGT THEREFORE HV BACKED OFF ON RA/SN MIX UNTIL CLOSER TO 09Z. 00Z EURO IS EVEN SLOWER THAN 12Z RUN BY ABOUT 6 HRS. TRENDS INDICATING THAT IMPENDING SYSTEM WL SLOW DOWN EVEN FURTHER AND LATER SHIFTS WL HV TO MONITOR PROGRESS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... 330 AM UPDATE...MINOR TWEEKS TO MED RNG BASED ON LATEST HPC GUIDANCE...BUT OVERALL GIST OF FCST REMAINS UNCHANGED. PREV BLO... 2 PM UPDATE... FOLLOWED HPC GUIDANCE. BEST SHOT FOR PRECIPITATION WILL COME EARLY IN THE PERIOD AS A COLD FRONT MOVES THROUGH MONDAY NIGHT. MAY END AS SOME LIGHT SNOW...ESPECIALLY OVER THE HIGHER TERRAIN EARLY TUESDAY MORNING. PREFERRED THE MORE UNSETTLED HPC GUIDANCE (MORE EURO BASED) THAN THE GFS. THIS SOLUTION SHOWS A TROF...COLDER AIR...AND SNOW SHOWERS THROUGH MID-WEEK. THE GFS IS MORE ZONAL (NORTHWEST FLOW) WITH VARIOUS SHORT WAVES BEFORE A TROF DEVELOPS IN THE EAST BY THE END OF THE WEEK. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... 430 AM UPDATE...AREA OF LOW CLD/STRATUS HAS DVLPD ACRS THE ERN FINGER LAKES. 1000-950 RUC RH APPEARS TO CAPTURE THIS...SUGGESTING THAT THE WRN PERIPHERY COULD BRUSH ITH...AND HAVE ADDED POTNL IFR FOR EARLY THIS MRNG THERE. IF THIS AREA HOLDS TOGETHER AS IT DROPS SWD IT COULD AFFECT BGM TWDS 12Z. PREV BLO... 330 AM UPDATE...ADDED POTNL FOR IFR AT SYR THIS MRNG AS PATCHY STRATUS/FOG HAS DVLPD SE OF LAKE ONTARIO. PREV BLO... VFR WILL PREVAIL THRU 06Z SUN WITH SKC TO BKN250 XPCTD. PATCHY LOW LVL STRATUS COULD DVLP TWDS DAYBREAK OVER PORTIONS OF CNTRL NY BUT PROBS TOO LOW TO INCLUDE IN TAFS. WINDS TDA N TO NW 5-10 KTS...BECMG E TO SE TNGT ARND 5 KTS. .OUTLOOK... SAT NIGHT/SUN...VFR. SUN NGT TO MON...MVFR IN -SHRA. MON NGT TO TUE...MVFR/IFR WITH RAIN CHANGING TO SNOW. WED...MVFR POSSIBLE ESPECIALLY CNY TERMINALS IN SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...PVN NEAR TERM...PVN SHORT TERM...PVN LONG TERM...HEDEN AVIATION...
AREA FORECAST DISCUSSION
NWS BISMARCK ND
856 AM CST SAT MAR 9 2013 .DISCUSSION...LATEST WATER VAPOR IMAGERY SHOWS THE NORTHERN STREAM TROUGH NOW WORKING THROUGH NORTHWEST NORTH DAKOTA...WHILE THE SOUTHERN STREAM UPPER LOW IS CIRCULATING OVER NORTHWEST NEW MEXICO. RADAR IMAGERY AND LATEST RAP MODEL INDICATE LIGHT SNOW ASSOCIATED WITH THE NORTHERN STREAM TROUGH WILL CONTINUE THROUGH THE MORNING IN NORTH CENTRAL NORTH DAKOTA AND WANE THIS AFTERNOON AS THE BEST LIFT SHUTS DOWN AND EXITS TO THE EAST. HAVE BUMPED POPS TO CATEGORICAL FOR THE REST OF THE MORNING IN MOST OF THE NORTH CENTRAL BASED ON RADAR AND SURFACE OBS. ALL INDICATIONS ARE THAT THE NEXT AREA OF PRECIPITATION ASSOCIATED WITH THE SOUTHERN STREAM LOW NOW IN SOUTH CENTRAL/SOUTHEAST SOUTH DAKOTA WILL GET SHUNTED EAST AND REMAIN EAST OF OUR FORECAST AREA. WILL CONTINUE TO ADVERTISE SLIGHT CHC POPS FOR SOME WAFFLING FURTHER WEST BASED ON THE 06Z RUN OF THE GFS/ECMWF. FOG WILL CONTINUE THROUGH THE MORNING WITH ISOLATED DENSE FOG OVER THE NEXT HOUR OR TWO. NO OTHER CHANGES WERE MADE TO THE CURRENT FORECAST. && .AVIATION...WIDESPREAD FOG AND IFR CIGS AND IFR/MVFR VSBYS WILL PREVAIL THROUGH MUCH OF THE MORNING WITH IMPROVING CONDITIONS DURING THE EARLY AFTERNOON. EXPECT PERIODS OF LIGHT SNOW...MAINLY AT KMOT THROUGH MID AFTERNOON. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...KS AVIATION...KS/LTH
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
855 AM MST SAT MAR 9 2013 .UPDATE... ISSUED AT 855 AM MST SAT MAR 9 2013 15Z SURFACE ANALYSIS HAD LOW OVER SOUTHEAST CO WITH NEARLY STATIONARY BOUNDARY INTO EASTERN ND. FIRST IMPULSE FROM STORM SYSTEM BROUGHT A BRIEF PERIOD OF -FZRA TO SOUTH CENTRAL SD...BUT CALLS TO SPOTTERS INDICATE CHANGEOVER TO SN HAS OCCURRED WITH 1-2 INCHES IN THE LAST COUPLE OF HOURS. 12Z RAP HAD A GOOD HANDLE ON CURRENT SENSIBLE WEATHER. NARROW BAND OF -SN/SN WILL CONTINUE THROUGH THIS AFTERNOON OVER SOUTH CENTRAL SD AS MAIN IMPULSE MOVES NORTHEAST INTO THE CENTRAL PLAINS. SNOW COINCIDENT WITH STRONG BAND OF 850-700MB FRONTOGENESIS...NORTHERN EDGE OF 700-500MB QG- FORCING...AND UNDER LEFT EXIT REGION OF 90KT JET STREAK RACING UP FRONT SIDE OF UPPER TROUGH OVER CO/NM. NORTHERN STREAM TROUGH WILL RACE SOUTHEAST...BRINGING MUCH DRIER AIR INTO CWA...AND THUS...AN END TO LINGERING -SN OVER NORTHWEST 2/3RDS OF CWA. 25-30KT 850MB WINDS WILL MIX OVER NORTHWEST SD LEADING TO WINDY CONDITIONS AS IN CURRENT FORECAST. UPDATE OUT SHORTLY. && .SHORT TERM...(TODAY THROUGH SUNDAY NIGHT) ISSUED AT 303 AM MST SAT MAR 9 2013 SW CONUS UPPER TROUGH CONTINUES TO PUSH ENE TOWARD THE REGION AS A NORTHERN STREAM TROUGH DROPS SE INTO THE DAKOTAS. VERY STRONG WAA RESPONSE ONGOING ACROSS THE CENTRAL PLAINS WILL SPREAD NORTH INTO SOUTH DAKOTA AND CONTINUE TO SUPPORT RAIN/ZR/AND EVEN A PERIOD OF TS CHANCES THIS MORNING GIVEN STEEP MID LEVEL LAPSE RATES AND A CONDITIONALLY UNSTABLE LAYER ALOFT. WAA WILL EVENTUALLY SUPPORT THE DEVELOPMENT OF A PRONOUNCED DEFORMATION ZONE ACROSS SCENTRAL SD...WITH VIGOROUS DEEP LAYER ASCENT AS THE NORTHERN STREAM TROUGH DROPS SOUTH AND SUPPORTS DEEP LAYER CAA. A PERIOD OF HEAVY SNOW CAN BE EXPECTED IN THE DEFORMATION BAND...WITH HIGH LIQUID WATER CONTENT AND LOW RATIO. THE LOCATION OF THIS SNOW BAND REMAINS SEMI-ELUSIVE GIVEN THE PRESENCE OF A STRONG WARM NOSE...AND FORECAST MODELS HAVE WAVERED PER ITS PLACEMENT. HOWEVER...LATEST GUIDANCE /ESP FROM THE NAM/ HAVE HONED THE LOCATION TO EASTERN TODD/MELLETTE AND MUCH OF TRIPP COUNTY. OTHERWISE...THE REMAINDER OF THE FA LOOKS TO BE FAIRLY DRY SAVE PERHAPS A LITTLE LIGHT SNOW OVER THE NORTHERN HILLS WHICH LOOKS IFFY AT THIS POINT GIVEN A SHARPLY DRYING BL. SUBSIDING FLOW WILL PREVAIL ON SUNDAY...WITH DEEP LAYER RIDGING AND DRY CONDITIONS. ROBUST WAA RESPONSE WILL PUSH NORTH IN SCENTRAL SD THIS MORNING...SUPPORTING RAIN/FREEZING RAIN/AND SNOW. RAIN AND FREEZING RAIN IS EXPECTED TO LAST THROUGH MID MORNING OVER PORTIONS OF MELLETTE/TODD/AND TRIPP COUNTIES WHERE SOME LIGHT ICING UP TO ONE TENTH OF A INCH WILL BE POSSIBLE UNTIL ALL PRECIP TRANSITIONS TO SNOW. MAIN LOBE OF DEEP LAYER ASCENT WILL SPREAD INTO SCENTRAL SD MID TO LATE MORNING...WITH A STRENGTHENING LL DEFORMATION ZONE. STRONG LIFT CENTERED IN THE SNOW GROWTH ZONE WILL SUPPORT A VERY INTENSE BAND OF HEAVY SNOW FOR 3-6 HOURS. HEAVY SNOWFALL RATES ARE EXPECTED WITH LOCATIONS IN THE BAND EXPECTED TO SEE 3-5 INCHES. LOCALLY HIGHER AMOUNTS WILL BE POSSIBLE BEFORE SNOW TAPERS OFF THIS EVENING. A SHARP CUT OFF IN PRECIP IS EXPECTED...SUPPORTING MAINLY DRY CONDITIONS ACROSS THE NW 1/2-2/3. HAVE DROPPED THE WINTER WEATHER ADV FOR THE TWO NW COUNTIES...GIVEN LACK OF SIG PRECIP. STRONG PRESSURE RISES WILL ENSUE IN A CAA REGIME SUPPORTING GUSTY NW WINDS. STRONGEST WINDS WILL BE IN THE LEE OF THE BH AND ADJACENT PLAINS GIVEN FLOW ENHANCEMENT AROUND THE BH. SUSTAINED WINDS OF 25 TO 30 MPH WITH GUSTS TO AROUND 50 MPH ARE EXPECTED. HAVE ISSUED A WIND ADV FOR THIS. 15 TO 30 MPH WINDS WILL SPREAD INTO SCNTRL SD THIS AFTERNOON AND EVENING AND MAY SUPPORT AREAS OF BLOWING SNOW DEPENDING ON BL TEMPS. MANY FORECAST SOLUTIONS OFFER TEMPS IN LOWER 30S BY AFTERNOON WHICH COULD HAMPER SNOW LIFTING POTENTIAL THERE. ADJUSTED POPS TO FIT ABOVE CONCERNS...WITH SOME ADJUSTMENT TO TEMPS. SUNDAY...FAIRLY QUIET WEATHER TO PREVAIL WITH A PERIOD OF SHORTWAVE RIDGING. WAA EXPECTED TO INFLUENCE TEMPS ACROSS THE WESTERN HALF OF THE FA...WITH EASTERN AREAS LIKELY REMAINING UNDER A SUBSIDENCE INVERSION AND CONTINUED NORTHERLY FLOW. SNOW COVER WILL ALSO INFLUENCE TEMPS OVER SCENTRAL AREAS. LOWS WILL BE TRICKY SUNDAY NIGHT OVER THE SNOW PACK...WHERE SIG T DROP OFFS ARE POSSIBLE GIVEN CLEAR SKIES AND LIGHT WINDS. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 303 AM MST SAT MAR 9 2013 RIDGE BUILDS OVER THE WESTERN CONUS...WITH AXIS SLOWLY SHIFTING TOWARDS THE PLAINS THROUGH THE EXTENDED. THIS WILL BRING MILD TEMPS THROUGH MID-WEEK...WITH WARMER TEMPS EXPECTED FOR THE LAST PART OF THE WORK WEEK. OCCASIONAL WEAK DISTURBANCES MOVING THROUGH MAY BRING A FEW LIGHT SHOWERS THROUGH MID-WEEK...WITH GENERALLY DRY CONDITIONS FOR THE END OF THE WORK WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 303 AM MST SAT MAR 9 2013 WIDESPREAD IFR CONDITIONS WILL CONT THRU WRN SD INTO PTNS OF NERN WY THROUGH MUCH OF THE DAY. OVER S CNTRL SD FZRA/SN EXPECTED THIS MORN...WITH A TRANSITION TO ALL SN THIS AFTERNOON. ELSEWHERE... PERIODS OF SNOW ARE EXPECTED WITH THE GREATEST CHANCES TOWARDS THE NEBRASKA BORDER. PRECIP WILL DIMINISH FROM NORTHWEST TO SOUTHEAST LATER THIS AFTERNOON INTO THIS EVE WITH CIGS/VIS IMPROVING. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 5 PM MST /6 PM CST/ THIS AFTERNOON FOR SDZ044-046-047-049. WIND ADVISORY UNTIL 7 PM MST THIS EVENING FOR SDZ026-030-031- 072>074. WY...NONE. && $$ UPDATE...HELGESON SHORT TERM...JC LONG TERM...77 AVIATION...77
AREA FORECAST DISCUSSION
NWS GOODLAND KS
147 PM MST SAT MAR 9 2013 .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 145 PM MST SAT MAR 9 2013 LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW LARGE SCALE TROUGH EXTENDING FROM CENTRAL CANADA AND ACROSS THE INTERMOUNTAIN WEST...WITH A CLOSED CENTER OVER NORTHERN NEW MEXICO. H7 TROUGH AXIS ALONG KS/CO BORDER. SATELLITE IMAGERY AND REGIONAL RADAR SHOWS DEFORMATION BAND JUST WEST OF H7 TROUGH AXIS ACROSS EASTERN EASTERN COLORADO EXTENDING NORTH THROUGH THE NEBRASKA PANHANDLE AND INTO SOUTH DAKOTA. DRY SLOT DEVELOPED AHEAD OF THE TROUGH EARLY THIS MORNING AND IS CURRENTLY IN PLACE OVER ALL BUT THE FAR WESTERN EXTENT OF CWA. AXIS OF MODEST INSTABILITY HAS DEVELOPED JUST EAST OF OUR CWA IN RESPONSE TO VERY MOIST BL AND STRONG WAA AHEAD OF SURFACE LOW. THUNDERSTORMS HAVE DEVELOPED ACROSS NORTH CENTRAL KANSAS AND CENTRAL NEBRASKA. SURFACE TD HAVE ALREADY BEEN DECREASING AT NORTON AND HILL CITY...SO THE THREAT FOR THUNDERSTORMS MAY BE DECREASING FOR OUR AREA. WE COULD STILL SEE A WINDOW FOR THUNDERSTORMS TO DEVELOP IN OUR EASTERN CWA THIS AFTERNOON BEFORE THE COLD FRONT PUSHES EAST...SO I KEPT A SLIGHT CHANCE OF THUNDERSTORMS GOING THROUGH 00Z FOR EASTERN LOCATIONS. THERE ARE DIFFERENCES REGARDING THE EVOLUTION OF SNOW BAND TONIGHT THOUGH MODEL CONSENSUS STILL SHOWS THIS BAND MOVING EAST AND PRODUCING HEAVY SNOW ACCUMULATIONS AROUND 7 INCHES ACROSS OUR NORTHWEST...AND LESSER AMOUNTS SOUTH AND EAST. THERE SHOULD BE A QUICK RAIN/SNOW CHANGE OVER IN THE WEST...WITH CHANGEOVER THIS EVENING IN THE EAST WHERE WARMER TEMPERATURES ARE STILL IN PLACE. UPSTREAM OBS ALREADY SHOW LIGHT SNOW IN YUMA COUNTY...IN LINE WITH CURRENT FORECAST TIMING. THE DEFORMATION BAND SHOULD WEAKEN AFTER 06Z AS LARGE SCALE FORCING BEGINS TO PULL EAST...AND DRY AIR ACROSS THE NORTHERN ROCKIES PUSHES SOUTH AND EAST. IT IS WORTH NOTING THAT THE LATEST GFS AND ECMWF ACTUALLY INDICATE THAT THIS SNOW BAND WILL HOLD TOGETHER IF NOT INTENSIFY AFTER 06Z WITH HIGHER AMOUNTS BY AS MUCH AS 2-3 INCHES MORE THAN CURRENT FORECAST. WITH RUC/NAM/GFS ALL SHOWING INSTABILITY WITHIN 700-500MB LAYER WITH THIS BAND...THERE MAY BE A CONNECTIVE COMPONENT THAT COULD SUPPORT LOCALLY HIGHER AMOUNTS IN LINE WITH THESE HIGHER TOTALS...HOWEVER IT IS HARD TO GAUGE WHERE THIS WILL SET UP AND HOW WIDESPREAD IT WILL BE. I ALSO THINK THE WINDOW FOR CONVECTIVE BANDING WILL BE DURING THE EVENING RATHER THAN AFTER 06Z...SINCE MODELS ARE GENERALLY INDICATING A DECREASE IN INSTABILITY AS DRY/STABLE AIR MOVES IN FROM THE NW BEHIND THIS BAND. WARM GROUND TEMPERATURES COULD LEAD TO ADDITIONAL MELTING WHICH COULD EAT INTO OUR SNOW AMOUNTS EARLY ON...HOWEVER AS SNOWFALL INTENSIFIES AND TEMPERATURES BEGIN TO DROP WE SHOULD START TO OVERCOME THIS. MODELS ARE STILL SHOWING STRONG H85 JET DEVELOPING BEHIND FRONT LATE THIS AFTERNOON AND EVENING. NAM WOULD INDICATE A SMALLER WINDOW FOR THE STRONGEST WINDS UP NORTH...HOWEVER IT STILL SHOWS POTENTIAL FOR GUSTS AROUND 35MPH THROUGH THE NIGHT UP NORTH...AND GUSTS 40-50MPH ACROSS THE SOUTH THROUGH MOST OF THE NIGHT. THIS SHOULD SUPPORT WIDESPREAD BLOWING SNOW WITH WHITE OUT CONDITIONS ACROSS THE AREA. I DECIDED AGAINST MAKING ANY WHOLESALE CHANGES TO FORECAST OR BLIZZARD WARNING TONIGHT WITH ONLY ADJUSTMENTS TO DETAILS AND RAIN/SNOW TIMING BASED ON CURRENT TRENDS. WE MAY NEED TO MAKE FURTHER ADJUSTMENTS AS THIS BAND STARTS MOVING EAST AND WE GET A BETTER HANDLE ON HOW QUICKLY IT WEAKENS LATE TONIGHT. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 145 PM MST SAT MAR 9 2013 THE STORM THAT IS AFFECTING OUR FORECAST AREA THIS WEEKEND WILL BE HEADING OUT OF THE PLAINS REGION AND WILL BE MOVING TOWARDS THE GREAT LAKES AND MISSISSIPPI VALLEY REGIONS ON SUNDAY NIGHT AND MONDAY. A COUPLE OF WEAK SHORT WAVE TROUGHS WILL MOVE ACROSS THE CENTRAL HIGH PLAINS REGION IN THE UPPER NORTHWEST FLOW MONDAY MORNING AND DURING THE DAY ON WEDNESDAY...OTHERWISE THE RIDGE THAT MOVES INTO THE WESTERN UNITED STATES DURING THE FIRST PART OF NEXT WEEK BECOMES A BROAD RIDGE OVER THE WESTERN UNITED STATES...EXTENDING FROM THE INTERMOUNTAIN REGION TO THE PLAINS STATES BY THE END OF THE WEEK. THE RIDGE APPEARS TO WEAKEN SOMEWHAT BY NEXT WEEKEND AS ANOTHER TROUGH APPROACHES THE WEST COAST...BUT THERE IS CURRENTLY A LARGE AMOUNT OF DISAGREEMENT IN THE MODELS OVER THE WEST COAST DURING THAT TIME PERIOD. BY NEXT SATURDAY...THE CENTRAL HIGH PLAINS REGION SEEMS TO STILL BE UNDER A WEAK RIDGE WITH A TRANSITION IN THE PATTERN UNDERWAY OVER THE WESTERN UNITED STATES. WITH UNIDIRECTIONAL NORTH TO NORTHWEST FLOW THROUGH THE ATMOSPHERE SUNDAY NIGHT AND MONDAY...BREEZY CONDITIONS COULD PERSIST THROUGH THAT TIME ACROSS THE FORECAST AREA. OTHER THAN SOME WIND EARLY IN THE LONG TERM PERIOD...THE CONDITIONS DURING THE LONG TERM PORTION OF THE FORECAST APPEAR TO BE BENIGN WITH NO PRECIPITATION EXPECTED AND GOOD AGREEMENT BETWEEN MODEL SOLUTIONS. TEMPERATURES WILL CONTINUE TO RISE EACH DAY WITH HIGH TEMPERATURES INCREASING FROM THE UPPER 40S AND LOWER 50S ON MONDAY TO THE UPPER 60S AND LOWER 70S BY FRIDAY. LOW TEMPERATURES WILL INCREASE FROM THE UPPER TEENS ON SUNDAY NIGHT TO THE UPPER 30S BY FRIDAY NIGHT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1035 AM MST SAT MAR 9 2013 EARLY IN THE TAF PERIOD IFR CIGS ASSOCIATED WITH STRATUS DECK WILL LINGER AT BOTH KGLD/KMCK...WITH LIGHT FOG AND MVFR VIS LINGERING. MAIN BAND OF RAIN/SNOW OVER EASTERN COLORADO IS EXPECTED TO OVERSPREAD BOTH TERMINALS THIS AFTERNOON WITH COVERAGE INCREASING LATE THIS AFTERNOON THROUGH THE EVENING. SHOULD SEE A GRADUAL REDUCTION IN AVIATION CONDITIONS WITH LIFR ASSOCIATED WITH SNOW AND BLOWING SNOW THIS EVENING THROUGH EARLY SUNDAY MORNING. BASED ON CURRENT TIMING I EXPECT THE MAIN BAND SHOULD WEAKEN AND SHIFT TO THE EAST WITH CONDITIONS IMPROVING AT KGLD AFTER 09Z AND THEN AROUND 10Z AT KMCK. VFR CIG/VIS IS EXPECTED BY MID MORNING AT BOTH TERMINALS WITH DRY/STABLE AIR MOVING IN ON BACK SIDE OF UPPER LOW. IT IS WORTH NOTING THAT THERE COULD BE A FEW THUNDERSTORM DEVELOP THIS AFTERNOON AHEAD OF COLD FRONT...HOWEVER THIS SHOULD BE EAST OF BOTH TERMINALS...SO I LEFT MENTION OF OUT TAFS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...BLIZZARD WARNING UNTIL 9 AM MDT /10 AM CDT/ SUNDAY FOR KSZ001- 013-027. BLIZZARD WARNING FROM 5 PM MST /6 PM CST/ THIS AFTERNOON TO 9 AM MDT /10 AM CDT/ SUNDAY FOR KSZ002>004-014>016-028-029-041- 042. CO...BLIZZARD WARNING UNTIL 9 AM MDT SUNDAY FOR COZ090>092. NE...BLIZZARD WARNING UNTIL 9 AM MDT /10 AM CDT/ SUNDAY FOR NEZ079- 080. BLIZZARD WARNING FROM 6 PM CST THIS EVENING TO 10 AM CDT SUNDAY FOR NEZ081. && $$ SHORT TERM...DR FS LONG TERM...LOCKHART AVIATION...DR
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1233 PM CST SAT MAR 9 2013 .UPDATE... ISSUED AT 1232 PM CST SAT MAR 9 2013 EARLY AFTERNOON UPDATE...SNOW REPORTS OF 3-6 INCHES ARE COMING IN FOR SEVERAL LOCATIONS ACROSS NORTH WESTERN/CENTRAL NEBRASKA...THUS THE MAIN DEFORMATION BAND IS BEHAVING AS IT SHOULD. OTHERWISE THE ONLY SIGNIFICANT CHANGE TO THE ONGOING FORECAST WAS TO INCLUDE THE MENTION OF THUNDER ACROSS FAR SOUTHEASTERN PORTIONS OF THE CWA. STORMS HAVE ALREADY DEVELOPED...WITH CG NOTED SOUTH OF MASON CITY OVER THE PAST HALF HOUR. UPDATE ISSUED AT 1021 CST SAT MAR 9 2013 OVERALL IDEA OF THE FORECAST REMAINS ON TRACK WITH ONLY MINOR REVISIONS TO FRESHEN UP WIND SPEEDS...TIMING OF THE SNOW CHANGEOVER...AND FREEZING RAIN AMOUNTS. PHONE CALLS IN AND AROUND KVTN THIS MORNING SUGGESTED ABOUT A TENTH OF AN INCH OF ICE OR LESS ACCUMULATION...THUS WILL TREND DOWN THE QUARTER OF AN INCH WE HAD GOING FOR THE CENTRAL SAND HILLS...WITH WORDING OF MINOR ICE ACCUMULATIONS. OTHERWISE ONCE THE CHANGE OVER TO SNOW OCCURS...SNOW RATES OF AN INCH PER HOUR HAVE BEEN NOTED UNDER THE HEAVIEST OF BANDS. 12Z NAM APPEARS REASONABLE AT THIS JUNCTURE...THUS TRENDED IN THAT DIRECTION. THE NARROW BAND OF QPF WILL CONTINUE THROUGH MID AFTERNOON ACROSS NORTHWEST NEBRASKA ALONG A STRONG BAND OF H7 FRONTOGENESIS AND WITH AID FROM THE LFQ OF A 90KT JET. SNOW ACCUMULATIONS OF 6 INCHES OR GREATER STILL APPEARS LIKELY ACROSS NORTHWEST NEBRASKA. BUT LATER TODAY...SNOW WILL BEGIN TO TAPER OFF BY LATE AFTERNOON AS THE NORTHERN STREAM RACES SOUTHEAST ACROSS THE NORTHERN PLAINS AND ALLOWS FOR THE INTRUSION OF DRIER AIR INTO THE NORTHERN REACHES OF THE CWA. HOWEVER ALL NEAR TERM SOLUTIONS DO INDICATE THE FORMATION OF A SECOND AREA OF DEFORMATION ACROSS FAR SOUTHEASTERN PORTIONS OF THE FORECAST AREA...ALIGNED NORTHEAST TO SOUTHWEST WITH THE EASTWARD ADVANCING MID LEVEL FRONTOGENETIC FORCING...FORECAST FOR THIS SECOND BAND APPEARS ON TRACK AT THIS TIME...WILL REVISIT EXPECTED SNOW AMOUNTS AS ADDITIONAL GUIDANCE COMES IN THIS MORNING. UPDATE ISSUED AT 700 AM CST SAT MAR 9 2013 NO NEW DATA WAS AVAILABLE FOR THE QPF FORECAST BUT INDICATIONS ARE THE RAP13 IS VERIFYING ACROSS NRN NEB WITH OVER 1/2 INCH OF ICE AT THE KVTN ASOS. AFTER SLOWING THE EASTERN PROGRESSION OF THE RAIN CHANGE LINE USING THE RUC...NORTH WINDS HAVE INCREASED AND NOW THE RAIN CHANGE LINE IS ROUGHLY FROM CHAPPELL TO THEDFORD TO AINSWORTH. SO THE NAM MAY BE VERIFYING BETTER AND IT WAS USED IN THE NEW FORECAST. A NEW WIND FORECAST USING NAM...GEM...MET AND MAV GUIDANCE PRODUCED GUSTS TO 50 MPH THIS AFTERNOON AND THIS EVENING WHICH IS CONSISTENT WITH THE 60KT BARRIER JET FCST BY BOTH MODELS. THIS STRUCTURE IS FCST TO SET UP ACROSS THE ERN PANHANDLE THIS MORNING AND MOVE SLOWLY EAST THIS AFTN AND TONIGHT ACTING AS A FOCUS FOR SNOW AND STRONG WINDS. THERE IS NO CHANGE TO THE DYNAMICS. STRONG FRONTOGENESIS HANGS UP ACROSS THE NORTHWEST TODAY AND DECAYS WHILE A NEW STRUCTURE DEVELOPS FARTHER EAST THIS EVENING. THE RAP HAS COME IN LINE WITH THE NAM AND ECM DEVELOPING THE NEW SNOW EAST OF THE FCST AREA WHILE THE 06Z GFS HANGS IT UP ACROSS NCNTL AND SWRN NEB...VERY TROUBLING. GIVEN THE VERY STRONG WINDS DEVELOPING...EVEN AN 1/2 INCH PER HOUR SNOWFALL RATE COULD PRODUCE BLIZZARD CONDITIONS. THE SNOW SHOULD GRADUALLY END OVERNIGHT AND SUNDAY MORNING WEST TO EAST WITH CLEARING SKIES TO FOLLOW. WINDY CONDITIONS CONTINUE SUNDAY MORNING IN THE EAST. UPDATE ISSUED AT 527 AM CST SAT MAR 9 2013 THE RAP13 MODEL SHOWS A SLOWER TRANSITION TO SNOW THAN THE NAM. IN FACT THE RAP CARRIES A BROAD AREA OF FREEZING RAIN AHEAD OF THE CHANGEOVER TO SNOW. THIS IS WELL SUPPORTED IN THE MODEL TEMPERATURE FIELDS. SO A NEW FORECAST IS OUT WHICH HEIGHTENS THE THREAT OF FREEZING RAIN. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 345 AM CST SAT MAR 9 2013 TWO ROUNDS OF THOUGHT WITH THE STORM. ONE IS FOR A STRONG FGEN FORCED BAND OF SNOW DEVELOPING ACROSS NORTHWEST NEBRASKA TODAY WHICH MOST SOLNS AGREE ON TO VARYING DEGREES. THE SECOND IS FOR ANOTHER STRONG BAND OF SNOW TO DEVELOP ACROSS SOUTH CENTRAL NEBRASKA TONIGHT AS THE FIRST BAND DECAYS. THE GEM REGIONAL AND GFS ARE VERY FAR NORTHWEST WITH THIS BAND SIGNALING A WINTER STORM FOR NCNTL NEB WHILE THE NAM AND ECM ARE SAFELY EAST OF THE FCST AREA. A BLEND OF NAM...GEM AND ECM WERE USED FOR THE LATEST FCST WHICH PROVIDES A WINTER STORM ACROSS THE NORTHWEST AND A WINTER WEATHER ADVISORY ELSEWHERE. HOWEVER THE NAM AND RAP SHOW A VERY STRONG BARRIER JET DEVELOPING THIS EVENING STRETCHING NORTH-SOUTH ALONG AND WEST OF HIGHWAY 83 WHICH COULD EASILY SUPPORT A WINTER STORM IF THE FRONTOGENESIS WAS APPROPRIATELY JUXTAPOSED. THIS IS NOT THE CASE AS THE NAM SHOWS THE FGEN AND HEAVY QPF MOSTLY EAST OF THE FCST AREA. THE RAP MEANWHILE NOSES THE PV1.5 ANOMALY INTO SRN NEB AT 02Z AND DEVELOPS SOME HEAVY SNOW ACROSS SWRN NEB. THIS IS A CONCERN WHICH WILL BE CLOSELY MONITORED. THE STRONG BARRIER JET WILL EASILY SUPPORT 30 MPH WINDS WITH GUSTS TO 45 MPH. IN FACT THE NAM AND RAP SHOW GUSTS TO 60 MPH AT 00Z-03Z...THE HEIGHT OF THE STORM ACROSS SWRN AND NCNTL NEB. SO EVERYONE OUTSIDE OF THE WINTER STORM WARNING HAS BEEN PLACED IN A WINTER WEATHER ADVISORY FOR 3 TO 5 INCHES OF SNOW AND 30 TO 45 MPH WINDS. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 345 AM CST SAT MAR 9 2013 MAJOR SPRING/WINTER STORM WILL BE EXITING SUNDAY MORNING WITH SOME LINGERING LIGHT SNOW ACROSS THE FAR EASTERN COUNTIES. WINDS WILL CONTINUE TO BE GUSTY...AND WILL HIGHLIGHT PATCHY BLOWING SNOW WHERE FALLING SNOW IS EXPECTED. PENDING TOTAL SNOW AND HOW FLUFFY IT IS...MAY NEED TO CONTINUE BLOWING SNOW FURTHER WEST EARLY SUNDAY. STILL QUESTIONING HOW FAR WEST THE HEAVY BAND OF SNOW OVER CENTRAL NEB WILL BE. SUNDAY HIGHS...WITH COLD HIGH PRESSURE BUILDING SOUTH ACROSS THE NORTHERN PLAINS AND MUCH IF NOT ALL OF THE AREA EXPECTED TO SEE A SNOW COVER...SHOULD HOLD CLOSE TO 30 DEGREES. ALTHOUGH THE SUN WILL SPREADING FROM WEST TO EAST...WHICH SHOULD HELP TO START TO MELT ROADWAYS. SUNDAY NIGHT WITH AN ELONGATED HIGH ACROSS THE WESTERN PLAINS...LIGHT WINDS AND MOSTLY CLEAR SKIES ALONG WITH SNOW PACK...TEMPS SHOULD TANK. WIDESPREAD TEENS...WHICH MAY BE CONSERVATIVE. MONDAY INTO MID WEEK RIDGE BUILDS ACROSS THE WEST...WITH A TROUGH TO PUSH ALONG THE NORTHERN STREAM...ACROSS SOUTHERN CANADA AND THE GREAT LAKES. WEAK DISTURBANCE TO MOVE ALONG THE NW FLOW ACROSS THE AREA...HOWEVER MOISTURE LIMITED AND DOUBT ANYTHING WILL REACH THE GROUND AS TIMING IS A LITTLE SLOWER WITH PASSAGE MORE OF A DAYTIME AND THE HEAT OF THE DAY SHOULD BE ENOUGH TO KEEP ANYTHING FROM HITTING THE GROUND. ALSO EARLY IN THE WEEK AS THE SNOW MELTS WILL NEED TO MONITOR FOR OVERNIGHT/MORNING FOG. RIDGE EXPANDS AS THE WEEK CONTINUES...WITH STRONG WAA ALOFT WITH THE WESTERN PART OF THE CWA SEEING DOUBLE DIGIT 850 TEMPS. QUESTION WILL BE HOW LONG CAN THE SNOW REMAIN AND DAMPEN TEMPS. GUIDANCE PUSHES HIGHS INTO THE 50S AND 60S FOR WEDNESDAY AND THURSDAY. AS IS TYPICAL WITH MANY MARCH SNOW STORMS...EXPECT THIS SNOW NOT TO STAY LONG. ALTHOUGH WEST WINDS ON THE LIGHT SIDE...LESS THAN 15 MPH...SHOULD BE ENOUGH TO HELP MIX WITH THE DOWNSLOPE COMPONENT AND HAVE FOLLOWED CLOSER TO GUIDANCE FOR THE LATER HALF OF THE WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1153 AM CST SAT MAR 9 2013 EXPECTING WIDESPREAD IFR/LIFR CONDITIONS TO CONTINUE THROUGH 03Z TONIGHT...WITH SNOW...BLOWING SNOW...FREEZING RAIN...THUNDERSTORMS...AND RAIN ALL POSSIBLE FOR AREA TERMINALS. KVTN...KTIF...KANW AND KOGA HAVE SWITCHED OVER TO SNOW...WITH PERIODIC VISIBILITY REDUCTIONS TO 1/2SM. AT KLBF...KIML...KONL & KBBW...ONLY LIGHT RAIN HAS THUS FAR BEEN OBSERVED...HOWEVER CONDITIONS ARE EXPECTED TO DETERIORATE THIS AFTERNOON AS COLD AIR UNDERCUTS THE FALLING PRECIPITATION. A BRIEF PERIOD OF FREEZING RAIN MAY BE POSSIBLE WHERE THE CHANGE OVER TO SNOW HAS NOT OCCURRED...INCLUDING THE KLBF TERMINAL. IN ADDITION...STRONG NORTHERLY WIND GUSTS IN EXCESS OF 30KTS WILL CONTINUE THROUGH THE TAF FORECAST PERIOD...WHICH WOULD LOWER VISIBILITY FURTHER IF SNOW IS FALLING. LATE THIS EVENING...IMPROVEMENT TO MVFR/VFR SHOULD COMMENCE FROM NORTHWEST TO SOUTHEAST. && .LBF WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ006>010-025>029-036>038-057>059-069>071. WINTER STORM WARNING UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ004- 005-022>024-035-056-094. && $$ UPDATE...JACOBS SHORT TERM...CDC LONG TERM...MASEK AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1154 AM CST SAT MAR 9 2013 .UPDATE... ISSUED AT 1021 CST SAT MAR 9 2013 OVERALL IDEA OF THE FORECAST REMAINS ON TRACK WITH ONLY MINOR REVISIONS TO FRESHEN UP WIND SPEEDS...TIMING OF THE SNOW CHANGEOVER...AND FREEZING RAIN AMOUNTS. PHONE CALLS IN AND AROUND KVTN THIS MORNING SUGGESTED ABOUT A TENTH OF AN INCH OF ICE OR LESS ACCUMULATION...THUS WILL TREND DOWN THE QUARTER OF AN INCH WE HAD GOING FOR THE CENTRAL SAND HILLS...WITH WORDING OF MINOR ICE ACCUMULATIONS. OTHERWISE ONCE THE CHANGE OVER TO SNOW OCCURS...SNOW RATES OF AN INCH PER HOUR HAVE BEEN NOTED UNDER THE HEAVIEST OF BANDS. 12Z NAM APPEARS REASONABLE AT THIS JUNCTURE...THUS TRENDED IN THAT DIRECTION. THE NARROW BAND OF QPF WILL CONTINUE THROUGH MID AFTERNOON ACROSS NORTHWEST NEBRASKA ALONG A STRONG BAND OF H7 FRONTOGENESIS AND WITH AID FROM THE LFQ OF A 90KT JET. SNOW ACCUMULATIONS OF 6 INCHES OR GREATER STILL APPEARS LIKELY ACROSS NORTHWEST NEBRASKA. BUT LATER TODAY...SNOW WILL BEGIN TO TAPER OFF BY LATE AFTERNOON AS THE NORTHERN STREAM RACES SOUTHEAST ACROSS THE NORTHERN PLAINS AND ALLOWS FOR THE INTRUSION OF DRIER AIR INTO THE NORTHERN REACHES OF THE CWA. HOWEVER ALL NEAR TERM SOLUTIONS DO INDICATE THE FORMATION OF A SECOND AREA OF DEFORMATION ACROSS FAR SOUTHEASTERN PORTIONS OF THE FORECAST AREA...ALIGNED NORTHEAST TO SOUTHWEST WITH THE EASTWARD ADVANCING MID LEVEL FRONTOGENETIC FORCING...FORECAST FOR THIS SECOND BAND APPEARS ON TRACK AT THIS TIME...WILL REVISIT EXPECTED SNOW AMOUNTS AS ADDITIONAL GUIDANCE COMES IN THIS MORNING. UPDATE ISSUED AT 700 AM CST SAT MAR 9 2013 NO NEW DATA WAS AVAILABLE FOR THE QPF FORECAST BUT INDICATIONS ARE THE RAP13 IS VERIFYING ACROSS NRN NEB WITH OVER 1/2 INCH OF ICE AT THE KVTN ASOS. AFTER SLOWING THE EASTERN PROGRESSION OF THE RAIN CHANGE LINE USING THE RUC...NORTH WINDS HAVE INCREASED AND NOW THE RAIN CHANGE LINE IS ROUGHLY FROM CHAPPELL TO THEDFORD TO AINSWORTH. SO THE NAM MAY BE VERIFYING BETTER AND IT WAS USED IN THE NEW FORECAST. A NEW WIND FORECAST USING NAM...GEM...MET AND MAV GUIDANCE PRODUCED GUSTS TO 50 MPH THIS AFTERNOON AND THIS EVENING WHICH IS CONSISTENT WITH THE 60KT BARRIER JET FCST BY BOTH MODELS. THIS STRUCTURE IS FCST TO SET UP ACROSS THE ERN PANHANDLE THIS MORNING AND MOVE SLOWLY EAST THIS AFTN AND TONIGHT ACTING AS A FOCUS FOR SNOW AND STRONG WINDS. THERE IS NO CHANGE TO THE DYNAMICS. STRONG FRONTOGENESIS HANGS UP ACROSS THE NORTHWEST TODAY AND DECAYS WHILE A NEW STRUCTURE DEVELOPS FARTHER EAST THIS EVENING. THE RAP HAS COME IN LINE WITH THE NAM AND ECM DEVELOPING THE NEW SNOW EAST OF THE FCST AREA WHILE THE 06Z GFS HANGS IT UP ACROSS NCNTL AND SWRN NEB...VERY TROUBLING. GIVEN THE VERY STRONG WINDS DEVELOPING...EVEN AN 1/2 INCH PER HOUR SNOWFALL RATE COULD PRODUCE BLIZZARD CONDITIONS. THE SNOW SHOULD GRADUALLY END OVERNIGHT AND SUNDAY MORNING WEST TO EAST WITH CLEARING SKIES TO FOLLOW. WINDY CONDITIONS CONTINUE SUNDAY MORNING IN THE EAST. UPDATE ISSUED AT 527 AM CST SAT MAR 9 2013 THE RAP13 MODEL SHOWS A SLOWER TRANSITION TO SNOW THAN THE NAM. IN FACT THE RAP CARRIES A BROAD AREA OF FREEZING RAIN AHEAD OF THE CHANGEOVER TO SNOW. THIS IS WELL SUPPORTED IN THE MODEL TEMPERATURE FIELDS. SO A NEW FORECAST IS OUT WHICH HEIGHTENS THE THREAT OF FREEZING RAIN. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 345 AM CST SAT MAR 9 2013 TWO ROUNDS OF THOUGHT WITH THE STORM. ONE IS FOR A STRONG FGEN FORCED BAND OF SNOW DEVELOPING ACROSS NORTHWEST NEBRASKA TODAY WHICH MOST SOLNS AGREE ON TO VARYING DEGREES. THE SECOND IS FOR ANOTHER STRONG BAND OF SNOW TO DEVELOP ACROSS SOUTH CENTRAL NEBRASKA TONIGHT AS THE FIRST BAND DECAYS. THE GEM REGIONAL AND GFS ARE VERY FAR NORTHWEST WITH THIS BAND SIGNALING A WINTER STORM FOR NCNTL NEB WHILE THE NAM AND ECM ARE SAFELY EAST OF THE FCST AREA. A BLEND OF NAM...GEM AND ECM WERE USED FOR THE LATEST FCST WHICH PROVIDES A WINTER STORM ACROSS THE NORTHWEST AND A WINTER WEATHER ADVISORY ELSEWHERE. HOWEVER THE NAM AND RAP SHOW A VERY STRONG BARRIER JET DEVELOPING THIS EVENING STRETCHING NORTH-SOUTH ALONG AND WEST OF HIGHWAY 83 WHICH COULD EASILY SUPPORT A WINTER STORM IF THE FRONTOGENESIS WAS APPROPRIATELY JUXTAPOSED. THIS IS NOT THE CASE AS THE NAM SHOWS THE FGEN AND HEAVY QPF MOSTLY EAST OF THE FCST AREA. THE RAP MEANWHILE NOSES THE PV1.5 ANOMALY INTO SRN NEB AT 02Z AND DEVELOPS SOME HEAVY SNOW ACROSS SWRN NEB. THIS IS A CONCERN WHICH WILL BE CLOSELY MONITORED. THE STRONG BARRIER JET WILL EASILY SUPPORT 30 MPH WINDS WITH GUSTS TO 45 MPH. IN FACT THE NAM AND RAP SHOW GUSTS TO 60 MPH AT 00Z-03Z...THE HEIGHT OF THE STORM ACROSS SWRN AND NCNTL NEB. SO EVERYONE OUTSIDE OF THE WINTER STORM WARNING HAS BEEN PLACED IN A WINTER WEATHER ADVISORY FOR 3 TO 5 INCHES OF SNOW AND 30 TO 45 MPH WINDS. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 345 AM CST SAT MAR 9 2013 MAJOR SPRING/WINTER STORM WILL BE EXITING SUNDAY MORNING WITH SOME LINGERING LIGHT SNOW ACROSS THE FAR EASTERN COUNTIES. WINDS WILL CONTINUE TO BE GUSTY...AND WILL HIGHLIGHT PATCHY BLOWING SNOW WHERE FALLING SNOW IS EXPECTED. PENDING TOTAL SNOW AND HOW FLUFFY IT IS...MAY NEED TO CONTINUE BLOWING SNOW FURTHER WEST EARLY SUNDAY. STILL QUESTIONING HOW FAR WEST THE HEAVY BAND OF SNOW OVER CENTRAL NEB WILL BE. SUNDAY HIGHS...WITH COLD HIGH PRESSURE BUILDING SOUTH ACROSS THE NORTHERN PLAINS AND MUCH IF NOT ALL OF THE AREA EXPECTED TO SEE A SNOW COVER...SHOULD HOLD CLOSE TO 30 DEGREES. ALTHOUGH THE SUN WILL SPREADING FROM WEST TO EAST...WHICH SHOULD HELP TO START TO MELT ROADWAYS. SUNDAY NIGHT WITH AN ELONGATED HIGH ACROSS THE WESTERN PLAINS...LIGHT WINDS AND MOSTLY CLEAR SKIES ALONG WITH SNOW PACK...TEMPS SHOULD TANK. WIDESPREAD TEENS...WHICH MAY BE CONSERVATIVE. MONDAY INTO MID WEEK RIDGE BUILDS ACROSS THE WEST...WITH A TROUGH TO PUSH ALONG THE NORTHERN STREAM...ACROSS SOUTHERN CANADA AND THE GREAT LAKES. WEAK DISTURBANCE TO MOVE ALONG THE NW FLOW ACROSS THE AREA...HOWEVER MOISTURE LIMITED AND DOUBT ANYTHING WILL REACH THE GROUND AS TIMING IS A LITTLE SLOWER WITH PASSAGE MORE OF A DAYTIME AND THE HEAT OF THE DAY SHOULD BE ENOUGH TO KEEP ANYTHING FROM HITTING THE GROUND. ALSO EARLY IN THE WEEK AS THE SNOW MELTS WILL NEED TO MONITOR FOR OVERNIGHT/MORNING FOG. RIDGE EXPANDS AS THE WEEK CONTINUES...WITH STRONG WAA ALOFT WITH THE WESTERN PART OF THE CWA SEEING DOUBLE DIGIT 850 TEMPS. QUESTION WILL BE HOW LONG CAN THE SNOW REMAIN AND DAMPEN TEMPS. GUIDANCE PUSHES HIGHS INTO THE 50S AND 60S FOR WEDNESDAY AND THURSDAY. AS IS TYPICAL WITH MANY MARCH SNOW STORMS...EXPECT THIS SNOW NOT TO STAY LONG. ALTHOUGH WEST WINDS ON THE LIGHT SIDE...LESS THAN 15 MPH...SHOULD BE ENOUGH TO HELP MIX WITH THE DOWNSLOPE COMPONENT AND HAVE FOLLOWED CLOSER TO GUIDANCE FOR THE LATER HALF OF THE WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1153 AM CST SAT MAR 9 2013 EXPECTING WIDESPREAD IFR/LIFR CONDITIONS TO CONTINUE THROUGH 03Z TONIGHT...WITH SNOW...BLOWING SNOW...FREEZING RAIN...THUNDERSTORMS...AND RAIN ALL POSSIBLE FOR AREA TERMINALS. KVTN...KTIF...KANW AND KOGA HAVE SWITCHED OVER TO SNOW...WITH PERIODIC VISIBILITY REDUCTIONS TO 1/2SM. AT KLBF...KIML...KONL & KBBW...ONLY LIGHT RAIN HAS THUS FAR BEEN OBSERVED...HOWEVER CONDITIONS ARE EXPECTED TO DETERIORATE THIS AFTERNOON AS COLD AIR UNDERCUTS THE FALLING PRECIPITATION. A BRIEF PERIOD OF FREEZING RAIN MAY BE POSSIBLE WHERE THE CHANGE OVER TO SNOW HAS NOT OCCURRED...INCLUDING THE KLBF TERMINAL. IN ADDITION...STRONG NORTHERLY WIND GUSTS IN EXCESS OF 30KTS WILL CONTINUE THROUGH THE TAF FORECAST PERIOD...WHICH WOULD LOWER VISIBILITY FURTHER IF SNOW IS FALLING. LATE THIS EVENING...IMPROVEMENT TO MVFR/VFR SHOULD COMMENCE FROM NORTHWEST TO SOUTHEAST. && .LBF WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ006-008-025-026-036-057-058-069. WINTER WEATHER ADVISORY UNTIL 7 AM CDT SUNDAY FOR NEZ007-009-010- 027>029-037-038-059-070-071. WINTER STORM WARNING UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ004- 005-022>024-035-056-094. && $$ UPDATE...JACOBS SHORT TERM...CDC LONG TERM...MASEK AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1021 AM CST SAT MAR 9 2013 .UPDATE... ISSUED AT 1021 CST SAT MAR 9 2013 OVERALL IDEA OF THE FORECAST REMAINS ON TRACK WITH ONLY MINOR REVISIONS TO FRESHEN UP WIND SPEEDS...TIMING OF THE SNOW CHANGEOVER...AND FREEZING RAIN AMOUNTS. PHONE CALLS IN AND AROUND KVTN THIS MORNING SUGGESTED ABOUT A TENTH OF AN INCH OF ICE OR LESS ACCUMULATION...THUS WILL TREND DOWN THE QUARTER OF AN INCH WE HAD GOING FOR THE CENTRAL SAND HILLS...WITH WORDING OF MINOR ICE ACCUMULATIONS. OTHERWISE ONCE THE CHANGE OVER TO SNOW OCCURS...SNOW RATES OF AN INCH PER HOUR HAVE BEEN NOTED UNDER THE HEAVIEST OF BANDS. 12Z NAM APPEARS REASONABLE AT THIS JUNCTURE...THUS TRENDED IN THAT DIRECTION. THE NARROW BAND OF QPF WILL CONTINUE THROUGH MID AFTERNOON ACROSS NORTHWEST NEBRASKA ALONG A STRONG BAND OF H7 FRONTOGENESIS AND WITH AID FROM THE LFQ OF A 90KT JET. SNOW ACCUMULATIONS OF 6 INCHES OR GREATER STILL APPEARS LIKELY ACROSS NORTHWEST NEBRASKA. BUT LATER TODAY...SNOW WILL BEGIN TO TAPER OFF BY LATE AFTERNOON AS THE NORTHERN STREAM RACES SOUTHEAST ACROSS THE NORTHERN PLAINS AND ALLOWS FOR THE INTRUSION OF DRIER AIR INTO THE NORTHERN REACHES OF THE CWA. HOWEVER ALL NEAR TERM SOLUTIONS DO INDICATE THE FORMATION OF A SECOND AREA OF DEFORMATION ACROSS FAR SOUTHEASTERN PORTIONS OF THE FORECAST AREA...ALIGNED NORTHEAST TO SOUTHWEST WITH THE EASTWARD ADVANCING MID LEVEL FRONTOGENETIC FORCING...FORECAST FOR THIS SECOND BAND APPEARS ON TRACK AT THIS TIME...WILL REVISIT EXPECTED SNOW AMOUNTS AS ADDITIONAL GUIDANCE COMES IN THIS MORNING. UPDATE ISSUED AT 700 AM CST SAT MAR 9 2013 NO NEW DATA WAS AVAILABLE FOR THE QPF FORECAST BUT INDICATIONS ARE THE RAP13 IS VERIFYING ACROSS NRN NEB WITH OVER 1/2 INCH OF ICE AT THE KVTN ASOS. AFTER SLOWING THE EASTERN PROGRESSION OF THE RAIN CHANGE LINE USING THE RUC...NORTH WINDS HAVE INCREASED AND NOW THE RAIN CHANGE LINE IS ROUGHLY FROM CHAPPELL TO THEDFORD TO AINSWORTH. SO THE NAM MAY BE VERIFYING BETTER AND IT WAS USED IN THE NEW FORECAST. A NEW WIND FORECAST USING NAM...GEM...MET AND MAV GUIDANCE PRODUCED GUSTS TO 50 MPH THIS AFTERNOON AND THIS EVENING WHICH IS CONSISTENT WITH THE 60KT BARRIER JET FCST BY BOTH MODELS. THIS STRUCTURE IS FCST TO SET UP ACROSS THE ERN PANHANDLE THIS MORNING AND MOVE SLOWLY EAST THIS AFTN AND TONIGHT ACTING AS A FOCUS FOR SNOW AND STRONG WINDS. THERE IS NO CHANGE TO THE DYNAMICS. STRONG FRONTOGENESIS HANGS UP ACROSS THE NORTHWEST TODAY AND DECAYS WHILE A NEW STRUCTURE DEVELOPS FARTHER EAST THIS EVENING. THE RAP HAS COME IN LINE WITH THE NAM AND ECM DEVELOPING THE NEW SNOW EAST OF THE FCST AREA WHILE THE 06Z GFS HANGS IT UP ACROSS NCNTL AND SWRN NEB...VERY TROUBLING. GIVEN THE VERY STRONG WINDS DEVELOPING...EVEN AN 1/2 INCH PER HOUR SNOWFALL RATE COULD PRODUCE BLIZZARD CONDITIONS. THE SNOW SHOULD GRADUALLY END OVERNIGHT AND SUNDAY MORNING WEST TO EAST WITH CLEARING SKIES TO FOLLOW. WINDY CONDITIONS CONTINUE SUNDAY MORNING IN THE EAST. UPDATE ISSUED AT 527 AM CST SAT MAR 9 2013 THE RAP13 MODEL SHOWS A SLOWER TRANSITION TO SNOW THAN THE NAM. IN FACT THE RAP CARRIES A BROAD AREA OF FREEZING RAIN AHEAD OF THE CHANGEOVER TO SNOW. THIS IS WELL SUPPORTED IN THE MODEL TEMPERATURE FIELDS. SO A NEW FORECAST IS OUT WHICH HEIGHTENS THE THREAT OF FREEZING RAIN. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 345 AM CST SAT MAR 9 2013 TWO ROUNDS OF THOUGHT WITH THE STORM. ONE IS FOR A STRONG FGEN FORCED BAND OF SNOW DEVELOPING ACROSS NORTHWEST NEBRASKA TODAY WHICH MOST SOLNS AGREE ON TO VARYING DEGREES. THE SECOND IS FOR ANOTHER STRONG BAND OF SNOW TO DEVELOP ACROSS SOUTH CENTRAL NEBRASKA TONIGHT AS THE FIRST BAND DECAYS. THE GEM REGIONAL AND GFS ARE VERY FAR NORTHWEST WITH THIS BAND SIGNALING A WINTER STORM FOR NCNTL NEB WHILE THE NAM AND ECM ARE SAFELY EAST OF THE FCST AREA. A BLEND OF NAM...GEM AND ECM WERE USED FOR THE LATEST FCST WHICH PROVIDES A WINTER STORM ACROSS THE NORTHWEST AND A WINTER WEATHER ADVISORY ELSEWHERE. HOWEVER THE NAM AND RAP SHOW A VERY STRONG BARRIER JET DEVELOPING THIS EVENING STRETCHING NORTH-SOUTH ALONG AND WEST OF HIGHWAY 83 WHICH COULD EASILY SUPPORT A WINTER STORM IF THE FRONTOGENESIS WAS APPROPRIATELY JUXTAPOSED. THIS IS NOT THE CASE AS THE NAM SHOWS THE FGEN AND HEAVY QPF MOSTLY EAST OF THE FCST AREA. THE RAP MEANWHILE NOSES THE PV1.5 ANOMALY INTO SRN NEB AT 02Z AND DEVELOPS SOME HEAVY SNOW ACROSS SWRN NEB. THIS IS A CONCERN WHICH WILL BE CLOSELY MONITORED. THE STRONG BARRIER JET WILL EASILY SUPPORT 30 MPH WINDS WITH GUSTS TO 45 MPH. IN FACT THE NAM AND RAP SHOW GUSTS TO 60 MPH AT 00Z-03Z...THE HEIGHT OF THE STORM ACROSS SWRN AND NCNTL NEB. SO EVERYONE OUTSIDE OF THE WINTER STORM WARNING HAS BEEN PLACED IN A WINTER WEATHER ADVISORY FOR 3 TO 5 INCHES OF SNOW AND 30 TO 45 MPH WINDS. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 345 AM CST SAT MAR 9 2013 MAJOR SPRING/WINTER STORM WILL BE EXITING SUNDAY MORNING WITH SOME LINGERING LIGHT SNOW ACROSS THE FAR EASTERN COUNTIES. WINDS WILL CONTINUE TO BE GUSTY...AND WILL HIGHLIGHT PATCHY BLOWING SNOW WHERE FALLING SNOW IS EXPECTED. PENDING TOTAL SNOW AND HOW FLUFFY IT IS...MAY NEED TO CONTINUE BLOWING SNOW FURTHER WEST EARLY SUNDAY. STILL QUESTIONING HOW FAR WEST THE HEAVY BAND OF SNOW OVER CENTRAL NEB WILL BE. SUNDAY HIGHS...WITH COLD HIGH PRESSURE BUILDING SOUTH ACROSS THE NORTHERN PLAINS AND MUCH IF NOT ALL OF THE AREA EXPECTED TO SEE A SNOW COVER...SHOULD HOLD CLOSE TO 30 DEGREES. ALTHOUGH THE SUN WILL SPREADING FROM WEST TO EAST...WHICH SHOULD HELP TO START TO MELT ROADWAYS. SUNDAY NIGHT WITH AN ELONGATED HIGH ACROSS THE WESTERN PLAINS...LIGHT WINDS AND MOSTLY CLEAR SKIES ALONG WITH SNOW PACK...TEMPS SHOULD TANK. WIDESPREAD TEENS...WHICH MAY BE CONSERVATIVE. MONDAY INTO MID WEEK RIDGE BUILDS ACROSS THE WEST...WITH A TROUGH TO PUSH ALONG THE NORTHERN STREAM...ACROSS SOUTHERN CANADA AND THE GREAT LAKES. WEAK DISTURBANCE TO MOVE ALONG THE NW FLOW ACROSS THE AREA...HOWEVER MOISTURE LIMITED AND DOUBT ANYTHING WILL REACH THE GROUND AS TIMING IS A LITTLE SLOWER WITH PASSAGE MORE OF A DAYTIME AND THE HEAT OF THE DAY SHOULD BE ENOUGH TO KEEP ANYTHING FROM HITTING THE GROUND. ALSO EARLY IN THE WEEK AS THE SNOW MELTS WILL NEED TO MONITOR FOR OVERNIGHT/MORNING FOG. RIDGE EXPANDS AS THE WEEK CONTINUES...WITH STRONG WAA ALOFT WITH THE WESTERN PART OF THE CWA SEEING DOUBLE DIGIT 850 TEMPS. QUESTION WILL BE HOW LONG CAN THE SNOW REMAIN AND DAMPEN TEMPS. GUIDANCE PUSHES HIGHS INTO THE 50S AND 60S FOR WEDNESDAY AND THURSDAY. AS IS TYPICAL WITH MANY MARCH SNOW STORMS...EXPECT THIS SNOW NOT TO STAY LONG. ALTHOUGH WEST WINDS ON THE LIGHT SIDE...LESS THAN 15 MPH...SHOULD BE ENOUGH TO HELP MIX WITH THE DOWNSLOPE COMPONENT AND HAVE FOLLOWED CLOSER TO GUIDANCE FOR THE LATER HALF OF THE WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 537 AM CST SAT MAR 9 2013 EXPECTING IFR/LIFR TO CONTINUE THROUGH 03Z THIS EVENING IN SNOW...BLOWING SNOW...FOG...RAIN AND FREEZING RAIN. THEREAFTER AN IMPROVEMENT TO MVFR/VFR SHOULD COMMENCE FROM NORTHWEST TO SOUTHEAST. WINDS TODAY WILL INCREASE TO 36030G40KT AND DIMINISH LATE THIS EVENING TO 34020G30KT BY 12Z SUNDAY. && .LBF WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ006-008-025-026-036-057-058-069. WINTER WEATHER ADVISORY UNTIL 7 AM CDT SUNDAY FOR NEZ007-009-010- 027>029-037-038-059-070-071. WINTER STORM WARNING UNTIL 7 AM CDT /6 AM MDT/ SUNDAY FOR NEZ004- 005-022>024-035-056-094. && $$ UPDATE...JACOBS SHORT TERM...CDC LONG TERM...MASEK AVIATION...CDC
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1142 AM MST SAT MAR 9 2013 .UPDATE... ISSUED AT 1137 AM MST SAT MAR 9 2013 CALLS TO SPOTTERS INDICATE 2 TO 5 INCHES OF SNOW HAS FALLEN ON PORTIONS OF SOUTH CENTRAL SD...MAINLY FROM SPRING CREEK TO FAR NORTHWEST TRIPP COUNTY. A BAND OF HEAVY SNOW...LOOKING CONVECTIVE AT TIMES ON RADAR/SATELLITE...HAS DEVELOPED IN NORTH CENTRAL NEBRASKA...MOVING INTO SOUTH CENTRAL SD. LATEST RAP MODEL INDICATES BAND WILL PERSIST FOR SEVERAL MORE HOURS WITH SNOWFALL RATES UP TO 1 INCH PER HOUR. STORM TOTAL SNOW WILL BE 4 TO 9 INCHES...SO HAVE UPGRADE TO A WARNING FOR TODD...MELLETTE...AND TRIPP COUNTIES. && .SHORT TERM...(TODAY THROUGH SUNDAY NIGHT) ISSUED AT 303 AM MST SAT MAR 9 2013 SW CONUS UPPER TROUGH CONTINUES TO PUSH ENE TOWARD THE REGION AS A NORTHERN STREAM TROUGH DROPS SE INTO THE DAKOTAS. VERY STRONG WAA RESPONSE ONGOING ACROSS THE CENTRAL PLAINS WILL SPREAD NORTH INTO SOUTH DAKOTA AND CONTINUE TO SUPPORT RAIN/ZR/AND EVEN A PERIOD OF TS CHANCES THIS MORNING GIVEN STEEP MID LEVEL LAPSE RATES AND A CONDITIONALLY UNSTABLE LAYER ALOFT. WAA WILL EVENTUALLY SUPPORT THE DEVELOPMENT OF A PRONOUNCED DEFORMATION ZONE ACROSS SCENTRAL SD...WITH VIGOROUS DEEP LAYER ASCENT AS THE NORTHERN STREAM TROUGH DROPS SOUTH AND SUPPORTS DEEP LAYER CAA. A PERIOD OF HEAVY SNOW CAN BE EXPECTED IN THE DEFORMATION BAND...WITH HIGH LIQUID WATER CONTENT AND LOW RATIO. THE LOCATION OF THIS SNOW BAND REMAINS SEMI-ELUSIVE GIVEN THE PRESENCE OF A STRONG WARM NOSE...AND FORECAST MODELS HAVE WAVERED PER ITS PLACEMENT. HOWEVER...LATEST GUIDANCE /ESP FROM THE NAM/ HAVE HONED THE LOCATION TO EASTERN TODD/MELLETTE AND MUCH OF TRIPP COUNTY. OTHERWISE...THE REMAINDER OF THE FA LOOKS TO BE FAIRLY DRY SAVE PERHAPS A LITTLE LIGHT SNOW OVER THE NORTHERN HILLS WHICH LOOKS IFFY AT THIS POINT GIVEN A SHARPLY DRYING BL. SUBSIDING FLOW WILL PREVAIL ON SUNDAY...WITH DEEP LAYER RIDGING AND DRY CONDITIONS. ROBUST WAA RESPONSE WILL PUSH NORTH IN SCENTRAL SD THIS MORNING...SUPPORTING RAIN/FREEZING RAIN/AND SNOW. RAIN AND FREEZING RAIN IS EXPECTED TO LAST THROUGH MID MORNING OVER PORTIONS OF MELLETTE/TODD/AND TRIPP COUNTIES WHERE SOME LIGHT ICING UP TO ONE TENTH OF A INCH WILL BE POSSIBLE UNTIL ALL PRECIP TRANSITIONS TO SNOW. MAIN LOBE OF DEEP LAYER ASCENT WILL SPREAD INTO SCENTRAL SD MID TO LATE MORNING...WITH A STRENGTHENING LL DEFORMATION ZONE. STRONG LIFT CENTERED IN THE SNOW GROWTH ZONE WILL SUPPORT A VERY INTENSE BAND OF HEAVY SNOW FOR 3-6 HOURS. HEAVY SNOWFALL RATES ARE EXPECTED WITH LOCATIONS IN THE BAND EXPECTED TO SEE 3-5 INCHES. LOCALLY HIGHER AMOUNTS WILL BE POSSIBLE BEFORE SNOW TAPERS OFF THIS EVENING. A SHARP CUT OFF IN PRECIP IS EXPECTED...SUPPORTING MAINLY DRY CONDITIONS ACROSS THE NW 1/2-2/3. HAVE DROPPED THE WINTER WEATHER ADV FOR THE TWO NW COUNTIES...GIVEN LACK OF SIG PRECIP. STRONG PRESSURE RISES WILL ENSUE IN A CAA REGIME SUPPORTING GUSTY NW WINDS. STRONGEST WINDS WILL BE IN THE LEE OF THE BH AND ADJACENT PLAINS GIVEN FLOW ENHANCEMENT AROUND THE BH. SUSTAINED WINDS OF 25 TO 30 MPH WITH GUSTS TO AROUND 50 MPH ARE EXPECTED. HAVE ISSUED A WIND ADV FOR THIS. 15 TO 30 MPH WINDS WILL SPREAD INTO SCNTRL SD THIS AFTERNOON AND EVENING AND MAY SUPPORT AREAS OF BLOWING SNOW DEPENDING ON BL TEMPS. MANY FORECAST SOLUTIONS OFFER TEMPS IN LOWER 30S BY AFTERNOON WHICH COULD HAMPER SNOW LIFTING POTENTIAL THERE. ADJUSTED POPS TO FIT ABOVE CONCERNS...WITH SOME ADJUSTMENT TO TEMPS. SUNDAY...FAIRLY QUIET WEATHER TO PREVAIL WITH A PERIOD OF SHORTWAVE RIDGING. WAA EXPECTED TO INFLUENCE TEMPS ACROSS THE WESTERN HALF OF THE FA...WITH EASTERN AREAS LIKELY REMAINING UNDER A SUBSIDENCE INVERSION AND CONTINUED NORTHERLY FLOW. SNOW COVER WILL ALSO INFLUENCE TEMPS OVER SCENTRAL AREAS. LOWS WILL BE TRICKY SUNDAY NIGHT OVER THE SNOW PACK...WHERE SIG T DROP OFFS ARE POSSIBLE GIVEN CLEAR SKIES AND LIGHT WINDS. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 303 AM MST SAT MAR 9 2013 RIDGE BUILDS OVER THE WESTERN CONUS...WITH AXIS SLOWLY SHIFTING TOWARDS THE PLAINS THROUGH THE EXTENDED. THIS WILL BRING MILD TEMPS THROUGH MID-WEEK...WITH WARMER TEMPS EXPECTED FOR THE LAST PART OF THE WORK WEEK. OCCASIONAL WEAK DISTURBANCES MOVING THROUGH MAY BRING A FEW LIGHT SHOWERS THROUGH MID-WEEK...WITH GENERALLY DRY CONDITIONS FOR THE END OF THE WORK WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1035 AM MST SAT MAR 9 2013 CONDITIONS IMPROVING OVER NE WY AND EXTRM WRN SD WITH CIGS AND VSBYS QUICKLY BECOMING VFR EXCEPT SOME LOW CLOUDS PERSISTING OVER THE BLACK HILLS. ELSEWHERE...OVER S CNTRL SD WIDESPREAD IFR AND LIFR CIGS AND VSBYS IN SNOW WILL CONTINUE INTO MID AFTN BEFORE GRADUALLY IMPROVING FROM NW TO SE AS SNOW MOVES OUT OF THE AREA. LOW CLOUDS WILL PERSIST UNTIL NEAR SUNSET OVER S CNTRL SD. NORTH AND NORTHWESTERLY WINDS OF 25-30 KTS WITH GUSTS UP TO 40KTS WILL COVER MOST OF THE FCST AREA...WITH STRONGEST WINDS JUST EAST OF THE BLACK HILLS BEFORE GRADUALLY DIMINISHING AFTER SUNSET. PATCHY LOW STRATUS IS LIKELY TO REDEVELOP OVER NE WY AND WRN PORTIONS OF SD AROUND 06Z TONIGHT. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 6 PM MST THIS EVENING FOR SDZ044. WINTER STORM WARNING UNTIL 7 PM CST THIS EVENING FOR SDZ046-047- 049. WIND ADVISORY UNTIL 7 PM MST THIS EVENING FOR SDZ026-030-031- 072>074. WY...NONE. && $$ UPDATE...HELGESON SHORT TERM...JC LONG TERM...77 AVIATION...BARBER
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1038 AM MST SAT MAR 9 2013 .UPDATE... ISSUED AT 855 AM MST SAT MAR 9 2013 15Z SURFACE ANALYSIS HAD LOW OVER SOUTHEAST CO WITH NEARLY STATIONARY BOUNDARY INTO EASTERN ND. FIRST IMPULSE FROM STORM SYSTEM BROUGHT A BRIEF PERIOD OF -FZRA TO SOUTH CENTRAL SD...BUT CALLS TO SPOTTERS INDICATE CHANGEOVER TO SN HAS OCCURRED WITH 1-2 INCHES IN THE LAST COUPLE OF HOURS. 12Z RAP HAD A GOOD HANDLE ON CURRENT SENSIBLE WEATHER. NARROW BAND OF -SN/SN WILL CONTINUE THROUGH THIS AFTERNOON OVER SOUTH CENTRAL SD AS MAIN IMPULSE MOVES NORTHEAST INTO THE CENTRAL PLAINS. SNOW COINCIDENT WITH STRONG BAND OF 850-700MB FRONTOGENESIS...NORTHERN EDGE OF 700-500MB QG- FORCING...AND UNDER LEFT EXIT REGION OF 90KT JET STREAK RACING UP FRONT SIDE OF UPPER TROUGH OVER CO/NM. NORTHERN STREAM TROUGH WILL RACE SOUTHEAST...BRINGING MUCH DRIER AIR INTO CWA...AND THUS...AN END TO LINGERING -SN OVER NORTHWEST 2/3RDS OF CWA. 25-30KT 850MB WINDS WILL MIX OVER NORTHWEST SD LEADING TO WINDY CONDITIONS AS IN CURRENT FORECAST. UPDATE OUT SHORTLY. && .SHORT TERM...(TODAY THROUGH SUNDAY NIGHT) ISSUED AT 303 AM MST SAT MAR 9 2013 SW CONUS UPPER TROUGH CONTINUES TO PUSH ENE TOWARD THE REGION AS A NORTHERN STREAM TROUGH DROPS SE INTO THE DAKOTAS. VERY STRONG WAA RESPONSE ONGOING ACROSS THE CENTRAL PLAINS WILL SPREAD NORTH INTO SOUTH DAKOTA AND CONTINUE TO SUPPORT RAIN/ZR/AND EVEN A PERIOD OF TS CHANCES THIS MORNING GIVEN STEEP MID LEVEL LAPSE RATES AND A CONDITIONALLY UNSTABLE LAYER ALOFT. WAA WILL EVENTUALLY SUPPORT THE DEVELOPMENT OF A PRONOUNCED DEFORMATION ZONE ACROSS SCENTRAL SD...WITH VIGOROUS DEEP LAYER ASCENT AS THE NORTHERN STREAM TROUGH DROPS SOUTH AND SUPPORTS DEEP LAYER CAA. A PERIOD OF HEAVY SNOW CAN BE EXPECTED IN THE DEFORMATION BAND...WITH HIGH LIQUID WATER CONTENT AND LOW RATIO. THE LOCATION OF THIS SNOW BAND REMAINS SEMI-ELUSIVE GIVEN THE PRESENCE OF A STRONG WARM NOSE...AND FORECAST MODELS HAVE WAVERED PER ITS PLACEMENT. HOWEVER...LATEST GUIDANCE /ESP FROM THE NAM/ HAVE HONED THE LOCATION TO EASTERN TODD/MELLETTE AND MUCH OF TRIPP COUNTY. OTHERWISE...THE REMAINDER OF THE FA LOOKS TO BE FAIRLY DRY SAVE PERHAPS A LITTLE LIGHT SNOW OVER THE NORTHERN HILLS WHICH LOOKS IFFY AT THIS POINT GIVEN A SHARPLY DRYING BL. SUBSIDING FLOW WILL PREVAIL ON SUNDAY...WITH DEEP LAYER RIDGING AND DRY CONDITIONS. ROBUST WAA RESPONSE WILL PUSH NORTH IN SCENTRAL SD THIS MORNING...SUPPORTING RAIN/FREEZING RAIN/AND SNOW. RAIN AND FREEZING RAIN IS EXPECTED TO LAST THROUGH MID MORNING OVER PORTIONS OF MELLETTE/TODD/AND TRIPP COUNTIES WHERE SOME LIGHT ICING UP TO ONE TENTH OF A INCH WILL BE POSSIBLE UNTIL ALL PRECIP TRANSITIONS TO SNOW. MAIN LOBE OF DEEP LAYER ASCENT WILL SPREAD INTO SCENTRAL SD MID TO LATE MORNING...WITH A STRENGTHENING LL DEFORMATION ZONE. STRONG LIFT CENTERED IN THE SNOW GROWTH ZONE WILL SUPPORT A VERY INTENSE BAND OF HEAVY SNOW FOR 3-6 HOURS. HEAVY SNOWFALL RATES ARE EXPECTED WITH LOCATIONS IN THE BAND EXPECTED TO SEE 3-5 INCHES. LOCALLY HIGHER AMOUNTS WILL BE POSSIBLE BEFORE SNOW TAPERS OFF THIS EVENING. A SHARP CUT OFF IN PRECIP IS EXPECTED...SUPPORTING MAINLY DRY CONDITIONS ACROSS THE NW 1/2-2/3. HAVE DROPPED THE WINTER WEATHER ADV FOR THE TWO NW COUNTIES...GIVEN LACK OF SIG PRECIP. STRONG PRESSURE RISES WILL ENSUE IN A CAA REGIME SUPPORTING GUSTY NW WINDS. STRONGEST WINDS WILL BE IN THE LEE OF THE BH AND ADJACENT PLAINS GIVEN FLOW ENHANCEMENT AROUND THE BH. SUSTAINED WINDS OF 25 TO 30 MPH WITH GUSTS TO AROUND 50 MPH ARE EXPECTED. HAVE ISSUED A WIND ADV FOR THIS. 15 TO 30 MPH WINDS WILL SPREAD INTO SCNTRL SD THIS AFTERNOON AND EVENING AND MAY SUPPORT AREAS OF BLOWING SNOW DEPENDING ON BL TEMPS. MANY FORECAST SOLUTIONS OFFER TEMPS IN LOWER 30S BY AFTERNOON WHICH COULD HAMPER SNOW LIFTING POTENTIAL THERE. ADJUSTED POPS TO FIT ABOVE CONCERNS...WITH SOME ADJUSTMENT TO TEMPS. SUNDAY...FAIRLY QUIET WEATHER TO PREVAIL WITH A PERIOD OF SHORTWAVE RIDGING. WAA EXPECTED TO INFLUENCE TEMPS ACROSS THE WESTERN HALF OF THE FA...WITH EASTERN AREAS LIKELY REMAINING UNDER A SUBSIDENCE INVERSION AND CONTINUED NORTHERLY FLOW. SNOW COVER WILL ALSO INFLUENCE TEMPS OVER SCENTRAL AREAS. LOWS WILL BE TRICKY SUNDAY NIGHT OVER THE SNOW PACK...WHERE SIG T DROP OFFS ARE POSSIBLE GIVEN CLEAR SKIES AND LIGHT WINDS. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 303 AM MST SAT MAR 9 2013 RIDGE BUILDS OVER THE WESTERN CONUS...WITH AXIS SLOWLY SHIFTING TOWARDS THE PLAINS THROUGH THE EXTENDED. THIS WILL BRING MILD TEMPS THROUGH MID-WEEK...WITH WARMER TEMPS EXPECTED FOR THE LAST PART OF THE WORK WEEK. OCCASIONAL WEAK DISTURBANCES MOVING THROUGH MAY BRING A FEW LIGHT SHOWERS THROUGH MID-WEEK...WITH GENERALLY DRY CONDITIONS FOR THE END OF THE WORK WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1035 AM MST SAT MAR 9 2013 CONDITIONS IMPROVING OVER NE WY AND EXTRM WRN SD WITH CIGS AND VSBYS QUICKLY BECOMING VFR EXCEPT SOME LOW CLOUDS PERSISTING OVER THE BLACK HILLS. ELSEWHERE...OVER S CNTRL SD WIDESPREAD IFR AND LIFR CIGS AND VSBYS IN SNOW WILL CONTINUE INTO MID AFTN BEFORE GRADUALLY IMPROVING FROM NW TO SE AS SNOW MOVES OUT OF THE AREA. LOW CLOUDS WILL PERSIST UNTIL NEAR SUNSET OVER S CNTRL SD. NORTH AND NORTHWESTERLY WINDS OF 25-30 KTS WITH GUSTS UP TO 40KTS WILL COVER MOST OF THE FCST AREA...WITH STRONGEST WINDS JUST EAST OF THE BLACK HILLS BEFORE GRADUALLY DIMINISHING AFTER SUNSET. PATCHY LOW STRATUS IS LIKELY TO REDEVELOP OVER NE WY AND WRN PORTIONS OF SD AROUND 06Z TONIGHT. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 5 PM MST /6 PM CST/ THIS AFTERNOON FOR SDZ044-046-047-049. WIND ADVISORY UNTIL 7 PM MST THIS EVENING FOR SDZ026-030-031- 072>074. WY...NONE. && $$ UPDATE...HELGESON SHORT TERM...JC LONG TERM...77 AVIATION...BARBER
AREA FORECAST DISCUSSION...UPDATED
NWS SAN ANGELO TX
212 PM CST SAT MAR 9 2013 .UPDATE... FORECAST WAS UPDATED TO INCREASE POPS ACROSS EASTERN SECTIONS THIS AFTERNOON AND TO INCLUDE SEVERE THUNDERSTORM WATCH 49. && .DISCUSSION... CONVECTION CONTINUES TO INCREASE ALONG THE PACIFIC FRONT/DRYLINE EARLY THIS AFTERNOON WHICH CURRENTLY EXTENDS FROM JUST EAST OF ABILENE...SOUTHWEST TO NEAR OZONA. LATEST RUC SEEMS TO HAVE A DECENT HANDLE ON CURRENT ACTIVITY AND INDICATES ADDITIONAL DEVELOPMENT ACROSS EASTERN PORTIONS THE HEARTLAND AND NORTHWEST HILL COUNTRY LATER THIS AFTERNOON. PER SPC COORDINATION...SEVERE THUNDERSTORM WATCH IS IN NOW IN EFFECT UNTIL 11 PM FOR THE HEARTLAND AND CALLAHAN COUNTY. INCREASED POPS ACCORDINGLY ACROSS EASTERN SECTIONS AND MADE ADJUSTMENTS TO TEMPS...DEWPOINTS AND WINDS TO ACCOUNT FOR TRENDS. UPDATED ZONES SENT. THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE ACROSS THE HEARTLAND AND NORTHWEST HILL COUNTRY LATER THIS EVENING WITH AN ADDITIONAL THREAT FOR SEVERE STORMS INTO THE OVERNIGHT HOURS. THE MAIN SEVERE WEATHER THREAT THIS AFTERNOON THROUGH TONIGHT WILL BE LARGE HAIL AND DAMAGING WINDS BUT AN ISOLATED TORNADO CANNOT BE RULED OUT. && .PREV DISCUSSION... /ISSUED 1201 PM CST SAT MAR 9 2013/ DISCUSSION... SEE 18Z AVIATION DISCUSSION. AVIATION... MAINLY AND MVFR FORECAST OVER THE NEXT 24 HOURS. SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS MOST OF WEST CENTRAL TEXAS TODAY AND INTO THIS EVENING AS A PACIFIC FRONT MOVE ACROSS THE AREA. SHOWERS AND ISOLATED THUNDERSTORMS ARE POSSIBLE OVER KABI...KSJT AND KSOA THROUGH MID AFTERNOON BUT CONFIDENCE NOT HIGH ENOUGH TO INCLUDE ANYTHING BUT VICINITY FOR NOW. EXPECT MORE CONVECTION TO DEVELOP OVER THE SOUTHEAST TERMINALS LATER THIS EVENING. WILL INCLUDE VCTS OVER KBBD AND KJCT 03-06Z AND AND REFINE THE FORECAST AS NEEDED BASED ON TRENDS. STORMS ARE EXPECTED TO CLEAR OUT TOMORROW MORNING AFTER 10Z WITH A COLD MOVING ACROSS THE AREA SUNDAY MORNING. EXPECT GUSTY NORTH TO NORTHWEST WINDS BEHIND THE FRONT TO PERSIST INTO THE AFTERNOON HOURS. PREV DISCUSSION... /ISSUED 539 AM CST SAT MAR 9 2013/ DISCUSSION... SEE THE 12Z AVIATION DISCUSSION BELOW. AVIATION... WIDESPREAD MVFR CIGS ARE AFFECTING MUCH OF WEST CENTRAL TX. HOWEVER...IT APPEARS THAT GRAVITY WAVES ASSOCIATED WITH THE VERY STRONG LOW LEVEL JET HAVE RESULTED IN AREAS OF SUBSIDENCE ON THE LEE SIDE OF THE HIGHER TERRAIN FEATURES...CREATING EAST/WEST CORRIDORS OF VFR CONDITIONS AT BOTH KABI AND KSJT. THESE AREAS MAY BRIEFLY FILL IN BUT AS DRIER AIR ADVECTS INTO THE AREA WE WILL SEE IMPROVING CIG HEIGHTS. CIGS ARE EXPECTED TO HANG ON THE LONGEST AT KABI/KJCT BUT THESE AREAS SHOULD EVENTUALLY GO VFR AS WELL BY MIDDAY. WINDS WILL VEER TO THE WEST SOUTHWEST AND REMAIN GUSTY THIS MORNING. THESE GUSTY CONDITIONS WILL CONTINUE AT KSJT/KABI BUT THE REMAINING AREAS SHOULD SEE SUSTAINED WINDS GENERALLY 12 KTS OR LESS THIS AFTERNOON. A SECONDARY COLD FRONT WILL MOVE ACROSS THE CWA OVERNIGHT AND SHIFT WINDS TO THE NORTHWEST. THE OTHER CONCERN THIS TAF PERIOD IS CONVECTION. A POTENT SYSTEM WILL PROVIDE ISOLATED LIGHT RAIN SHOWERS THIS MORNING BUT THE PRIMARY FOCUS WILL BE THIS EVENING IN THE VICINITY OF A PACIFIC COLD FRONT...MAINLY OVER THE SOUTHEAST TERMINALS. I DID INCLUDE A PROB30 GROUP FOR THUNDER AND MVFR CIGS AT KBBD/KJCT BEGINNING AT 23Z AS THUNDERSTORMS ARE EXPECTED TO DEVELOP IN THIS AREA AFTER PEAK HEATING. JOHNSON PREV DISCUSSION... /ISSUED 403 AM CST SAT MAR 9 2013/ SHORT TERM... A BROAD TROUGH CONTINUES TO MOVE SLOWLY ACROSS THE WESTERN CONUS...WITH THE PRIMARY CIRCULATION CURRENTLY LOCATED NEAR THE FOUR CORNERS. SYNOPTIC SCALE ASCENT WILL CONTINUE TO OVERSPREAD THE REGION AS THIS CYCLONE APPROACHES...INTERACTING WITH MORE FOCUSED MESOSCALE FORCING AND ABUNDANT LOWER TROPOSPHERIC MOISTURE TO ENHANCE CLOUD COVER AND PRECIP CHANCES. THE DYNAMICALLY ENHANCED LOW LEVEL JET IS HOWLING AT AROUND 50 KTS...BUT THE CORE OF THIS JET WILL SHIFT EAST DURING THE DAY AS THE TROUGH AXIS MOVES INTO WEST CENTRAL TX. SOUTH WINDS ARE CURRENTLY 20-30 MPH AT MANY AREAS WITH TEMPS IN THE LOW TO MID 60S. LIGHT RAIN SHOWERS HAVE DEVELOPED IN THE PAST HOUR OVER WESTERN NORTH TX...FROM ASPERMONT TO VERNON...AND SHOULD CONTINUE THIS TREND OVER THE NEXT SEVERAL HOURS. LIGHT RAIN SHOWERS WILL BE POSSIBLE ACROSS WEST CENTRAL TX THROUGH 18Z AND SHOULD BECOME MORE ORGANIZED AS THE SURFACE TROUGH /OR WEAK PACIFIC COLD FRONT/ MOVES EAST AND PROVIDES A STRONG LIFTING MECHANISM. OPTIMISTICALLY SPEAKING...I THINK WE WILL SEE A BROKEN LINE OF SHOWERS MOVE ACROSS THE BIG COUNTRY AND CONCHO VALLEY BETWEEN 12-18Z...SHIFTING INTO THE HEARTLAND AND EASTERN BIG COUNTRY AFTER 18Z. POINT SOUNDINGS STILL INDICATE THE PRESENCE OF AN ELEVATED MIXED LAYER...WHICH IS EFFECTIVELY ERODED BY 16Z OR SO. UNFORTUNATELY...THE BEST LIFT WILL BE OVER THE EASTERN ZONES BY THIS TIME...MEANING THAT DEEP CONVECTION IS UNLIKELY FOR THE WESTERN COUNTIES AND ONLY LIGHT PRECIPITATION IS ANTICIPATED THIS MORNING. TEMPS WILL WARM INTO THE LOW/MID 70S ACROSS THE CWA THIS AFTERNOON. AS THE SURFACE BOUNDARY SLOWS UP OVER THE EASTERN ZONES...THE LARGE SCALE ASCENT WILL CATCH UP AND ENHANCE THUNDERSTORM CHANCES DURING THE AFTERNOON/EVENING. WITH THE CAP GONE...UPDRAFTS SHOULD BE ABLE TO TAP INTO THE ANTICIPATED 1000-1500 J/KG OF INSTABILITY. STRONG DEEP LAYER SHEAR SHOULD PROMOTE ORGANIZED CONVECTION THIS AFTERNOON AND EVENING...MAINLY SOUTHEAST OF A BROWNWOOD TO SONORA LINE. SEVERE STORMS WILL BE A POSSIBILITY ACROSS THE SOUTHEAST THIS EVENING... WITH THE PRIMARY THREATS BEING LARGE HAIL AND DAMAGING WINDS. THIS CONVECTION WILL LIKELY CONTINUE ACROSS THE SOUTHEAST ZONES THROUGH 06Z BEFORE SLOWLY SHIFTING TO THE SOUTH AS DRIER AIR ADVECTS INTO THE CWA FROM THE WEST. JOHNSON LONG TERM... NEXT WEEK APPEARS DRY IN THE COMPUTER MODELS. MID/UPPER LEVEL MOISTURE SUNDAY MORNING WILL PUSH EAST AS THE AXIS OF AN UPPER SHORTWAVE MOVES THROUGH THE REGION. IT WILL BE WINDY SUNDAY WITH A TIGHT PRESSURE GRADIENT BEHIND A COLD FRONT. ALOFT...DRY NORTHWEST FLOW WILL BECOME ZONAL BY TUESDAY. CLEAR SKIES AND LIGHT WINDS ASSOCIATED WITH SURFACE RIDGING WILL BRING GOOD RADIATIONAL COOLING MONDAY AND TUESDAY MORNINGS...WITH LOW LYING AREAS FALLING BELOW THE FREEZING MARK. THERE WILL BE NICE REBOUND IN TEMPERATURES TUESDAY WITH RETURN OF SOUTHERLY WINDS. A DRY ATMOSPHERE AND SUNNY SKIES...WILL OTHERWISE ALLOW A LARGE DIURNAL VARIATION IN TEMPERATURE NEXT WEEK. FIRE WEATHER... CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED TODAY DURING THE MID/LATE AFTERNOON HOURS ACROSS THE WESTERN BIG COUNTRY AND NORTHWEST CONCHO VALLEY. WEST SOUTHWEST 20 FT WINDS ARE EXPECTED TO INCREASE TO 20 MPH IN THE WAKE OF A PACIFIC COLD FRONT WITH RELATIVE HUMIDITY VALUES FALLING TO 15 TO 20 PERCENT. THE CRITICAL FIRE WEATHER AREA WILL GENERALLY REMAIN ALONG/WEST OF A LINE FROM HASKELL TO ROBERT LEE. WE MAY SEE A FEW SHOWERS THIS MORNING BUT FINE FUELS ARE EXPECTED TO QUICKLY DRY. FARTHER SOUTH...WIND SPEEDS ARE EXPECTED TO REMAIN 15-20 MPH...RESULTING IN ELEVATED FIRE WEATHER CONDITIONS. RELATIVE HUMIDITIES WILL RECOVER TO 50-60 PERCENT TONIGHT WITH WEST TO NORTHWEST 20 FT WINDS GENERALLY 15 MPH OR LESS. EXPECT NORTH 20 FT WINDS OF 15-25 MPH ON SUNDAY AS A SECONDARY COLD FRONT MOVES THROUGH THE AREA. HOWEVER...COOLER CONDITIONS WILL KEEP RELATIVE HUMIDITIES ABOVE 20 PERCENT. MINIMUM RELATIVE HUMIDITIES WILL FALL TO NEAR 15 PERCENT ON MONDAY WITH 20 FT WINDS WILL REMAIN UNDER 15 MPH. THE REST OF THE WEEK LOOKS RELATIVELY QUIET. JOHNSON && .PRELIMINARY POINT TEMPS/POPS... ABILENE 74 41 55 27 60 / 20 10 5 5 0 SAN ANGELO 79 42 59 28 66 / 20 10 5 5 0 JUNCTION 79 46 63 25 66 / 20 80 10 5 0 && .SJT WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 6 PM CST THIS EVENING FOR THE FOLLOWING ZONES: COKE...FISHER...HASKELL...JONES...NOLAN...STERLING. && $$ 99/99
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1142 AM CST SAT MAR 9 2013 .AVIATION... GUSTY WESTERLY WINDS SUSTAINED AT 25-30 KTS WILL BE COMMON AT THE TERMINALS THROUGH THE AFTERNOON HOURS...AND A AWW REMAIN IN EFFECT AT KLBB THROUGH 23Z. THESE WINDS WILL CONTINUE TO LOFT BLDU WHICH MAY DROP VISIBILITIES INTO MVFR LEVELS AT KLBB. IN ADDITION...A FEW SPRINKLES COULD LOCALLY ENHANCE THE WINDS AT KLBB INTO EARLY THIS AFTERNOON. THE WINDS WILL GRADUALLY EASE A BIT THIS EVENING BUT ANOTHER COLD FRONT WILL MOVE THROUGH EARLY SUNDAY MORNING. WINDS WILL INCREASE AND SHIFT TO THE NORTH BEHIND THE FRONT AND SPEEDS COULD AGAIN APPROACH AWW CRITERION. IN ADDITION...SCT-BKN LOW CLOUDS MAY FILL IN BEHIND THE FRONT...AND COULD THREATEN OR BREACH MVFR LEVELS. && .PREV DISCUSSION... /ISSUED 1049 AM CST SAT MAR 9 2013/ UPDATE... ONGOING FORECAST REMAINS IN GOOD SHAPE. PACIFIC FRONT HAS CLEARED ALL BUT THE FAR SOUTHEAST ZONES AS OF 1030 AM. THUS...HAVE TRIMMED POPS FOR ALL BUT THE FAR SOUTHEAST ZONES WHERE A FEW SHOWERS AND ISOLATED STORMS WILL BE POSSIBLE FOR THE NEXT HOUR OR TWO. BEHIND THE FRONT...GUSTY WESTERLY WIND WERE ALREADY SPILLING IN FROM EASTERN NEW MEXICO WHERE SUSTAINED WINDS SPEEDS OF 30 TO 35 MPH WERE ALREADY NOTED IN THE WTM DATA AT HOBBS...TATUM...DORA AND MORTON. THESE STOUT WESTERLY WINDS WILL OVERSPREAD THE REMAINDER OF THE FA THROUGH THE LATE MORNING AND INTO THE AFTERNOON HOURS. THE LATEST RAP AND WRF-NAM DO INDICATE THE STRONGEST LOW TO MIDDLE LEVEL WIND CORES WILL BE POSITIONED ACROSS THE TEXAS PANHANDLE AND OVER THE SOUTHERN SOUTH AND ROLLING PLAINS INTO THE NORTHERN PERMIAN BASIN THIS AFTERNOON. THIS MAY BE WHERE THE STRONGEST WINDS OCCUR THROUGH THE AFTERNOON HOURS...THOUGH THE ENTIRE CWA SHOULD SEE SUSTAINED WESTERLY WINDS OF 25 TO 35 MPH...INITIALLY ON THE CAPROCK AND THEN SPREADING INTO THE ROLLING PLAINS THIS AFTERNOON. ONGOING WIND ADVISORY REMAINS VALID. IN ADDITION...THE GUSTY WINDS WILL ADVECT IN MUCH DRIER AIR AND LEAD TO A PERIOD OF ELEVATED TO CRITICAL FIRE WEATHER THIS AFTERNOON...THOUGH THE STATE OF THE FUELS SHOULD HELP MITIGATE THE OVERALL FIRE DANGER AND THE ONGOING FIRE DANGER STATEMENT REMAINS VALID. WINDS WILL DECREASE THIS EVENING...BUT THEY WILL BE REINVIGORATED EARLY SUNDAY BEHIND A CANADIAN COLD FRONT. PREV DISCUSSION... /ISSUED 449 AM CST SAT MAR 9 2013/ SHORT TERM... DRYLINE HAS REMAINED STATIONED OVER EASTERN NEW MEXICO THIS MORNING AS UPPER LOW CONTINUES SPINNING NEAR THE FOUR CORNERS REGION. EXPECT THIS FEATURE AND ASSOCIATED LIFT TO PUSH QUICKLY EAST WITH SOME ADDITIONAL SHOWER AND THUNDERSTORM ACTIVITY FORMING ALONG THE ATTENDANT PACIFIC FRONT. BOUNDARY LAYER STABILIZATION WILL LIKELY LIMIT THE SEVERITY OF ANY STORMS THAT DEVELOP...BUT ELEVATED INSTABILITY OWING TO STEEPENING LAPSE RATES WILL NONETHELESS PROMOTE THE THREAT OF SOME SMALL SIZED HAIL IF STORMS CAN BECOME ESTABLISHED IN OUR REGION. FOCUS WILL QUICKLY TURN TO DRIER AND WINDIER CONDITIONS IN WAKE OF THIS LOW. AN INCREASING PRESSURE GRADIENT WILL DEVELOP AS THE UPPER LOW PUSHES TOWARD WESTERN KANSAS AND CAUSES A SURFACE LOW TO DEEPEN. WHILE THE 200 NAUTICAL MILE H70 HEIGHT GRADIENT HAS TRENDED DOWNWARD TO NEAR 70 METERS...SUSTAINED SURFACE WINDS OF 30-35 MPH STILL LOOK INEVITABLE...THUS WARRANTING A WIND ADVISORY FROM 16-00Z TODAY. TROPOSPHERIC WIND MAXIMUMS WILL QUICKLY PUSH EAST THIS AFTERNOON OVER THE ROLLING PLAINS...NEGATING HIGH WIND WARNING CRITERIA ON THE FAVORED CAPROCK. BLOWING DUST WILL BE A CONCERN...ESPECIALLY ON THE CAPROCK. HIGHER RAINFALL AMOUNTS AND COVERAGE LAST NIGHT AND THIS MORNING WOULD HAVE LIMITED THIS POTENTIAL...BUT LOCATIONS SOUTHWEST OF LUBBOCK GENERALLY ONLY PICKED UP A FEW HUNDREDTHS OF AN INCH. AREAS AROUND PLAINVIEW TO LITTLEFIELD AND NORTHWEST RECEIVED A QUARTER OF AN INCH WITH ISOLATED REPORTS UP TO NEAR HALF AN INCH...BUT WIDESPREAD SIGNIFICANT RAIN BY AND LARGE WAS NOT THE RULE AS SITES SOUTH AND EAST OF LUBBOCK REMAINED DRY. A NORTHWEST TO SOUTHEAST GRADIENT IN TEMPERATURES WILL OCCUR THIS AFTERNOON AS THE COOL NATURED PACIFIC FRONT PUSHES THROUGH...RANGING FROM THE UPPER 50S ACROSS NORTHWEST ZONES TO MID 70S FOR THE SOUTHEASTERN REACHES OF THE FORECAST AREA. A CANADIAN FRONT WILL MOVE THROUGH TONIGHT FROM THE NORTHWEST AND KEEP WINDS IN THE 15-25 MPH RANGE. COLD AIR ADVECTION WILL AID IN COOLING OVERNIGHT LOWS INTO THE UPPER 20S TO MID 30S WEST OF THE ESCARPMENT...WHILE AREAS TO THE EAST WILL ONLY BOTTOM OUT IN THE UPPER 30S TO AROUND 40. LONG TERM... BY SUNDAY MORNING...THIS MORNING/S WEATHER MAKER SHOULD BE SITUATED OVER THE CENTRAL PLAINS WITH A TROUGH TRAILING BACK TO THE BAJA PENINSULA. A SUBTENDING LOBE WILL ROTATE AROUND THE BACK SIDE OF THE LOW ON SUNDAY BRINGING A BIT OF REINFORCING ENERGY FOR A CANADIAN FRONT DUE IN TONIGHT. NORTHWEST FLOW WILL THEN PERSIST FOR THE REMAINDER OF THE EXTENDED THOUGH SLOWLY FLATTENING AS NEGATIVELY TILTED RIDGE EXTENDS FROM THE DESERT SOUTHWEST INTO EXTREME WESTERN CANADA. AS FRONT PUSHES THROUGH EARLY SUNDAY...CONVECTION LOOKS TO BREAK OUT TO OUR SOUTHEAST AND CONTINUE IN THAT DIRECTION. TO OUR NORTH...SOME LIGHT WRAP-AROUND PRECIPITATION SHOULD BE ABLE TO GET GOING ON THE WESTERN PERIPHERY OF THE UPPER LOW AND MAY MAKE IT AS FAR SOUTH AS THE TEXAS PANHANDLE. STILL...WILL KEEP FORECAST DRY FOR OUR CWFA. WINDS WILL BE QUITE STOUT ON SUNDAY BEHIND THE FRONT WITH SPEEDS IN THE 20 TO 30 MPH RANGE. AFTER RETURN FLOW STARTS TO GET GOING LATE MONDAY...NEXT WEAK FRONT WILL TRY TO MAKE IT INTO THE NORTHWESTERN PANHANDLE TUESDAY MORNING AND AGAIN THURSDAY AND SATURDAY MORNINGS WITH LITTLE TO SHOW OTHER THAN A WIND SHIFT. DRY CONDITIONS TO PREVAIL WITH LOTS OF SUN FOR SPRING BREAK. FIRE WEATHER... MUCH DRIER AND WINDIER CONDITIONS BEHIND A PACIFIC FRONT WILL DROP MINIMUM RELATIVE HUMIDITY VALUES INTO THE TEENS TO LOW 20S AREAWIDE. PORTIONS OF THE SOUTHERN SOUTH PLAINS WILL DIP TO 15 PERCENT OR BELOW ALONG WITH MUCH OF THE ROLLING PLAINS WHERE TEMPERATURES WILL BE WARMER. WINDS WILL BE SUSTAINED AROUND 30 MPH WITH GUSTS OF 40-50 MPH. TEMPERATURES NOT TOO FAR ABOVE AVERAGE...A LACK OF DRY FUELS...AND A QUICKLY EASTWARD MOVING MID LEVEL JET MAXIMUM SHOULD PRECLUDE WIDESPREAD AND LONG DURATION RED FLAG MINUTES. WILL STILL EXPERIENCE ELEVATED TO CRITICAL CONDITIONS THIS AFTERNOON...SO WILL ISSUE A FIRE DANGER STATEMENT TO CONVEY THIS THREAT. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 57 27 47 25 60 / 0 0 0 0 0 TULIA 60 31 45 23 61 / 10 0 0 0 0 PLAINVIEW 61 31 47 23 62 / 10 0 0 0 0 LEVELLAND 63 33 51 27 64 / 0 0 0 0 0 LUBBOCK 64 34 50 26 63 / 10 0 0 0 0 DENVER CITY 63 33 52 29 63 / 0 0 0 0 0 BROWNFIELD 65 35 52 28 64 / 10 0 0 0 0 CHILDRESS 70 37 50 29 60 / 10 0 0 0 0 SPUR 69 40 52 28 62 / 10 0 0 0 0 ASPERMONT 76 39 52 29 61 / 30 0 0 0 0 && .LUB WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 6 PM CST THIS EVENING FOR THE FOLLOWING ZONES: TXZ021>044. && $$ 23/07/23
AREA FORECAST DISCUSSION...UPDATED
NWS LUBBOCK TX
1049 AM CST SAT MAR 9 2013 .UPDATE... ONGOING FORECAST REMAINS IN GOOD SHAPE. PACIFIC FRONT HAS CLEARED ALL BUT THE FAR SOUTHEAST ZONES AS OF 1030 AM. THUS...HAVE TRIMMED POPS FOR ALL BUT THE FAR SOUTHEAST ZONES WHERE A FEW SHOWERS AND ISOLATED STORMS WILL BE POSSIBLE FOR THE NEXT HOUR OR TWO. BEHIND THE FRONT...GUSTY WESTERLY WIND WERE ALREADY SPILLING IN FROM EASTERN NEW MEXICO WHERE SUSTAINED WINDS SPEEDS OF 30 TO 35 MPH WERE ALREADY NOTED IN THE WTM DATA AT HOBBS...TATUM...DORA AND MORTON. THESE STOUT WESTERLY WINDS WILL OVERSPREAD THE REMAINDER OF THE FA THROUGH THE LATE MORNING AND INTO THE AFTERNOON HOURS. THE LATEST RAP AND WRF-NAM DO INDICATE THE STRONGEST LOW TO MIDDLE LEVEL WIND CORES WILL BE POSITIONED ACROSS THE TEXAS PANHANDLE AND OVER THE SOUTHERN SOUTH AND ROLLING PLAINS INTO THE NORTHERN PERMIAN BASIN THIS AFTERNOON. THIS MAY BE WHERE THE STRONGEST WINDS OCCUR THROUGH THE AFTERNOON HOURS...THOUGH THE ENTIRE CWA SHOULD SEE SUSTAINED WESTERLY WINDS OF 25 TO 35 MPH...INITIALLY ON THE CAPROCK AND THEN SPREADING INTO THE ROLLING PLAINS THIS AFTERNOON. ONGOING WIND ADVISORY REMAINS VALID. IN ADDITION...THE GUSTY WINDS WILL ADVECT IN MUCH DRIER AIR AND LEAD TO A PERIOD OF ELEVATED TO CRITICAL FIRE WEATHER THIS AFTERNOON...THOUGH THE STATE OF THE FUELS SHOULD HELP MITIGATE THE OVERALL FIRE DANGER AND THE ONGOING FIRE DANGER STATEMENT REMAINS VALID. WINDS WILL DECREASE THIS EVENING...BUT THEY WILL BE REINVIGORATED EARLY SUNDAY BEHIND A CANADIAN COLD FRONT. && .PREV DISCUSSION... /ISSUED 558 AM CST SAT MAR 9 2013/ AVIATION... AN ISOLATED SHOWER OR THUNDERSTORM MAY STILL DEVELOP AHEAD OF THE PACIFIC FRONT THIS MORNING...BUT CHANCES ARE TOO LOW FOR MENTION WITHIN EITHER THE KLBB OR KCDS TERMINALS. KCDS SHOULD SEE SOME MVFR CEILINGS EARLY THIS MORNING BEFORE LIFTING BY MID MORNING. SOUTH WINDS WILL INCREASE AND VEER FROM NEAR 12 KNOTS EARLY THIS MORNING TO NEAR 30 KNOTS WITH GUSTS OF 40-45 KNOTS OUT OF THE WEST BY LATE MORNING. BLOWING DUST SHOULD BE PREVALENT ENOUGH TO PRODUCE MVFR VISIBILITIES AT KLBB FOR MUCH OF THE TIME LATER THIS MORNING AND THIS AFTERNOON GIVEN THE LACK OF ANY RAINFALL LAST NIGHT OR THIS MORNING. A LULL IN WINDS WILL TAKE PLACE AT BOTH TERMINALS FROM SHORTLY AFTER SUNSET THROUGH AN HOUR OR TWO AFTER MIDNIGHT...BEFORE A CANADIAN COLD FRONT MOVES IN FROM THE NORTH TO RAMP NORTHWEST WINDS UP TO NEAR 20 KNOTS WITH GUSTS TO 30 KNOTS. CLOUDS SHOULD BECOME REESTABLISHED AROUND FL030...BUT PREVAILING CEILINGS ARE NOT FORECASTED AT THIS TIME. PREV DISCUSSION... /ISSUED 449 AM CST SAT MAR 9 2013/ SHORT TERM... DRYLINE HAS REMAINED STATIONED OVER EASTERN NEW MEXICO THIS MORNING AS UPPER LOW CONTINUES SPINNING NEAR THE FOUR CORNERS REGION. EXPECT THIS FEATURE AND ASSOCIATED LIFT TO PUSH QUICKLY EAST WITH SOME ADDITIONAL SHOWER AND THUNDERSTORM ACTIVITY FORMING ALONG THE ATTENDANT PACIFIC FRONT. BOUNDARY LAYER STABILIZATION WILL LIKELY LIMIT THE SEVERITY OF ANY STORMS THAT DEVELOP...BUT ELEVATED INSTABILITY OWING TO STEEPENING LAPSE RATES WILL NONETHELESS PROMOTE THE THREAT OF SOME SMALL SIZED HAIL IF STORMS CAN BECOME ESTABLISHED IN OUR REGION. FOCUS WILL QUICKLY TURN TO DRIER AND WINDIER CONDITIONS IN WAKE OF THIS LOW. AN INCREASING PRESSURE GRADIENT WILL DEVELOP AS THE UPPER LOW PUSHES TOWARD WESTERN KANSAS AND CAUSES A SURFACE LOW TO DEEPEN. WHILE THE 200 NAUTICAL MILE H70 HEIGHT GRADIENT HAS TRENDED DOWNWARD TO NEAR 70 METERS...SUSTAINED SURFACE WINDS OF 30-35 MPH STILL LOOK INEVITABLE...THUS WARRANTING A WIND ADVISORY FROM 16-00Z TODAY. TROPOSPHERIC WIND MAXIMUMS WILL QUICKLY PUSH EAST THIS AFTERNOON OVER THE ROLLING PLAINS...NEGATING HIGH WIND WARNING CRITERIA ON THE FAVORED CAPROCK. BLOWING DUST WILL BE A CONCERN...ESPECIALLY ON THE CAPROCK. HIGHER RAINFALL AMOUNTS AND COVERAGE LAST NIGHT AND THIS MORNING WOULD HAVE LIMITED THIS POTENTIAL...BUT LOCATIONS SOUTHWEST OF LUBBOCK GENERALLY ONLY PICKED UP A FEW HUNDREDTHS OF AN INCH. AREAS AROUND PLAINVIEW TO LITTLEFIELD AND NORTHWEST RECEIVED A QUARTER OF AN INCH WITH ISOLATED REPORTS UP TO NEAR HALF AN INCH...BUT WIDESPREAD SIGNIFICANT RAIN BY AND LARGE WAS NOT THE RULE AS SITES SOUTH AND EAST OF LUBBOCK REMAINED DRY. A NORTHWEST TO SOUTHEAST GRADIENT IN TEMPERATURES WILL OCCUR THIS AFTERNOON AS THE COOL NATURED PACIFIC FRONT PUSHES THROUGH...RANGING FROM THE UPPER 50S ACROSS NORTHWEST ZONES TO MID 70S FOR THE SOUTHEASTERN REACHES OF THE FORECAST AREA. A CANADIAN FRONT WILL MOVE THROUGH TONIGHT FROM THE NORTHWEST AND KEEP WINDS IN THE 15-25 MPH RANGE. COLD AIR ADVECTION WILL AID IN COOLING OVERNIGHT LOWS INTO THE UPPER 20S TO MID 30S WEST OF THE ESCARPMENT...WHILE AREAS TO THE EAST WILL ONLY BOTTOM OUT IN THE UPPER 30S TO AROUND 40. LONG TERM... BY SUNDAY MORNING...THIS MORNING/S WEATHER MAKER SHOULD BE SITUATED OVER THE CENTRAL PLAINS WITH A TROUGH TRAILING BACK TO THE BAJA PENINSULA. A SUBTENDING LOBE WILL ROTATE AROUND THE BACK SIDE OF THE LOW ON SUNDAY BRINGING A BIT OF REINFORCING ENERGY FOR A CANADIAN FRONT DUE IN TONIGHT. NORTHWEST FLOW WILL THEN PERSIST FOR THE REMAINDER OF THE EXTENDED THOUGH SLOWLY FLATTENING AS NEGATIVELY TILTED RIDGE EXTENDS FROM THE DESERT SOUTHWEST INTO EXTREME WESTERN CANADA. AS FRONT PUSHES THROUGH EARLY SUNDAY...CONVECTION LOOKS TO BREAK OUT TO OUR SOUTHEAST AND CONTINUE IN THAT DIRECTION. TO OUR NORTH...SOME LIGHT WRAP-AROUND PRECIPITATION SHOULD BE ABLE TO GET GOING ON THE WESTERN PERIPHERY OF THE UPPER LOW AND MAY MAKE IT AS FAR SOUTH AS THE TEXAS PANHANDLE. STILL...WILL KEEP FORECAST DRY FOR OUR CWFA. WINDS WILL BE QUITE STOUT ON SUNDAY BEHIND THE FRONT WITH SPEEDS IN THE 20 TO 30 MPH RANGE. AFTER RETURN FLOW STARTS TO GET GOING LATE MONDAY...NEXT WEAK FRONT WILL TRY TO MAKE IT INTO THE NORTHWESTERN PANHANDLE TUESDAY MORNING AND AGAIN THURSDAY AND SATURDAY MORNINGS WITH LITTLE TO SHOW OTHER THAN A WIND SHIFT. DRY CONDITIONS TO PREVAIL WITH LOTS OF SUN FOR SPRING BREAK. FIRE WEATHER... MUCH DRIER AND WINDIER CONDITIONS BEHIND A PACIFIC FRONT WILL DROP MINIMUM RELATIVE HUMIDITY VALUES INTO THE TEENS TO LOW 20S AREAWIDE. PORTIONS OF THE SOUTHERN SOUTH PLAINS WILL DIP TO 15 PERCENT OR BELOW ALONG WITH MUCH OF THE ROLLING PLAINS WHERE TEMPERATURES WILL BE WARMER. WINDS WILL BE SUSTAINED AROUND 30 MPH WITH GUSTS OF 40-50 MPH. TEMPERATURES NOT TOO FAR ABOVE AVERAGE...A LACK OF DRY FUELS...AND A QUICKLY EASTWARD MOVING MID LEVEL JET MAXIMUM SHOULD PRECLUDE WIDESPREAD AND LONG DURATION RED FLAG MINUTES. WILL STILL EXPERIENCE ELEVATED TO CRITICAL CONDITIONS THIS AFTERNOON...SO WILL ISSUE A FIRE DANGER STATEMENT TO CONVEY THIS THREAT. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 57 27 47 25 60 / 0 0 0 0 0 TULIA 60 31 45 23 61 / 10 0 0 0 0 PLAINVIEW 61 31 47 23 62 / 10 0 0 0 0 LEVELLAND 63 33 51 27 64 / 0 0 0 0 0 LUBBOCK 64 34 50 26 63 / 10 0 0 0 0 DENVER CITY 63 33 52 29 63 / 0 0 0 0 0 BROWNFIELD 65 35 52 28 64 / 10 0 0 0 0 CHILDRESS 70 37 50 29 60 / 10 0 0 0 0 SPUR 69 40 52 28 62 / 10 0 0 0 0 ASPERMONT 76 39 52 29 61 / 30 0 0 0 0 && .LUB WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 6 PM CST THIS EVENING FOR THE FOLLOWING ZONES: TXZ021>044. && $$ 23/07