Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/22/13
AREA FORECAST DISCUSSION
NWS TUCSON AZ
845 PM MST THU MAR 21 2013
.SYNOPSIS...A WEATHER SYSTEM PASSING NORTHEAST OF THE AREA WILL
BRING WINDY CONDITIONS TO SOME LOCATIONS FRIDAY AND SATURDAY. EXPECT
A FEW DEGREES OF COOLING OVER THE WEEKEND.
&&
.DISCUSSION...ANOTHER 12 HOURS OF DENSE SHEAVES OF MAINLY CIRRUS
LEVEL CLOUD BEFORE CLEARING FROM THE WEST IN THE MORNING HOURS. 00Z
NAM12 AND LATEST HRRR TRENDS SHOWING NO SURPRISES. GUSTY WINDS THE
MAIN STORY WITH THE SYSTEM OVER THE NEXT 72 HOURS WITH ASSOCIATED
FIRE WEATHER CONCERNS.
PLEASE NOTE THAT THE CURRENT RED FLAG WARNING FOR FRIDAY AFTERNOON
AND FIRE WEATHER WATCH FOR SATURDAY AFTERNOON DOES NOT INCLUDE
EASTERN PIMA COUNTY. IT CURRENTLY INCLUDES ALMOST ALL OF COCHISE AND
GRAHAM COUNTIES...AND APPROXIMATELY THE SOUTHERN HALF OF GREENLEE
COUNTY. THE HAZARD MAP ON THE TWC WEBPAGE INCLUDES EASTERN PIMA AND
SANTA CRUZ COUNTIES DUE TO THE SIZE AND SHAPE OF FIRE WEATHER ZONE
148 (THE 3 FIRE WEATHER ZONES CAN BE SEEN ON THE FIRE WEATHER
FORECAST PAGE AT WWW.WRH.NOAA.GOV/FIREWX/?WFO=TWC). AS OF RIGHT NOW
WE DON`T EXPECT WINDS TO BE QUITE STRONG ENOUGH IN MOST OF EASTERN
PIMA AND SANTA CRUZ COUNTIES TO MERIT INCLUSION IN THE FIRE WEATHER
HEADLINES.
&&
.PREV DISCUSSION...THICK CIRRUS CLOUDS HAVE DOMINATED SOUTHERN
ARIZONA SKIES TODAY ALTHOUGH SOME THINNING OR BREAKS HAVE OCCURRED
NEAR THE INTERNATIONAL BORDER AND IN NORTHERN GRAHAM/GREENLEE
COUNTIES. UPSTREAM CLOUDS WILL CONTINUE ACROSS THE REGION INTO THE
NIGHT THEN THIN OUT FRIDAY MORNING IN MOST AREAS AS A UPPER TROUGH
PASSING WELL TO OUR NORTH PULLS THEM OUT OF THE AREA. THAT SAME
TROUGH WILL BRING ANOTHER SWATH OF CLOUDS ACROSS NRN AZ WHICH WILL
JUST SKIRT THE WHITE MOUNTAINS FRIDAY AFTERNOON. THE COOLER AIR
ALOFT COULD SQUEEZE OUT A STRAY SHOWER UP THERE.
BIGGEST STORY WILL BE THE INCREASED WINDS FRIDAY AND SATURDAY TO THE
SOUTH OF THE AFOREMENTIONED TROUGH PASSING BY. SOUTHERN ARIZONA
WINDS MAY FALL JUST SHORT OF WIND ADVISORY LEVELS OF SUSTAINED AT 30
MPH...BUT SHOULD BE STRONG ENOUGH TO SURPASS CRITICAL FIRE WEATHER
THRESHOLDS. SEE FIRE WEATHER DISCUSSION FOR DETAILS.
WHILE COOLER AIR WILL BEGIN TO ENTER THE AREA FRIDAY...BECAUSE OF
THE AMPLE SUNSHINE...TEMPERATURES SHOULD END UP SIMILAR TO
TODAY...MAYBE EVEN A DEGREE OR TWO WARMER WHERE ZERO SUN OCCURS
TODAY. 5-8 DEGREES OF COOLING IS EXPECTED FOR HIGH TEMPS THIS
WEEKEND...WHICH WILL BE BACK TO NORMAL LEVELS. WE SHOULD WARM BACK
UP AGAIN BY MIDWEEK AS WEAK HIGH PRESSURE RIDGING SETTLES IN...KD
&&
.AVIATION...HIGH CLOUDS WILL CONTINUE THROUGH EARLY FRIDAY MORNING.
WIND DIMINISHING TO LESS THEN 10 KTS THIS EVENING...THEN INCREASING
AFTER 22/18Z BECOMING WESTERLY 15-25 KTS WITH GUSTS ABOVE 35 KTS E
OF KTUS. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...STRONGER WINDS ARE FORECAST FRIDAY AND SATURDAY WITH
CRITICAL FIRE WEATHER CONDITIONS BEING FORECAST FOR MOST OF
GRAHAM...COCHISE AND GREENLEE COUNTIES BELOW 7000 FEET. HAVE
UPGRADED THE FIRE WEATHER WATCH ON FRIDAY TO A RED FLAG WARNING.
THERE IS A SLIGHT CHANCE FOR LIGHT PRECIPITATION IN THE WHITES ON
FRIDAY.
GUSTY WINDS RETURN TO THE AREA SATURDAY AFTERNOON WITH CRITICAL FIRE
WEATHER CONDITIONS BEING FORECAST FOR PRETTY MUCH IN THE SAME AREA
FROM FRIDAYS EVENT INCLUDING FURTHER NORTH INTO NORTHERN GRAHAM AND
GREENLEE COUNTIES. THE FIRE WEATHER WATCH IS STILL IN EFFECT FOR
SATURDAY MAINLY EAST OF TUCSON.
A LITTLE LESS WIND ON SUNDAY WITH A FEW AREAS IN FAR SOUTHEAST
COCHISE COUNTY APPROACHING CRITICAL FIRE WEATHER CONDITIONS DURING
THE AFTERNOON HOURS.
WINDS RETURN TO NORMAL DIURNAL TRENDS MONDAY AND TUESDAY. CONFIDENCE
IS LOW NEXT WEDNESDAY AND THURSDAY WITH RESPECTS TO POSSIBILITY OF
CHANCES OF PRECIPITATION.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FRIDAY NOON TO 8 PM MST FOR EASTERN FIRE
WEATHER ZONE AZZ148...INCLUDING MOST OF COCHISE AND GRAHAM
COUNTIES AND SOUTHERN HALF OF GREENLEE COUNTY.
FIRE WEATHER WATCH SATURDAY AFTERNOON AND EVENING FOR EASTERN FIRE
WEATHER ZONE AZZ148 AND SOUTHERN 2/3RD OF FIRE WEATHER ZONE
AZZ146...INCLUDING MOST OF COCHISE AND GRAHAM COUNTIES AND THE
SOUTHERN 2/3RDS OF GREENLEE COUNTY.
&&
$$
MEYER/DROZD/BROST
VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1029 AM MDT WED MAR 20 2013
.UPDATE...
&&
.SHORT TERM...CURRENT FORECASTS LOOK ON TRACK AT THIS TIME.
MOISTURE TO SPREAD ACROSS MOUNTAINS THIS AFTERNOON ALONG WITH SOME
MID LEVEL ASCENT. WITH LAPSE RATES AROUND 6 C/KM...SHOULD SEE SOME
SNOW SHOWERS DEVELOP...BEST CHANCE FOR SHOWERS LATE THIS AFTERNOON
OVER ZONE 31 AND THE REST OF THE MOUNTAINS TONIGHT WHEN THE LATEST
RAP SHOWS THE BEST ASCENT MOVING OVERHEAD. FAVORED OROGRAPHICS IN
WESTERLY FLOW...THOUGH SNOW AMOUNTS STILL APPEAR LESS THAN
ADVISORY FOR ZONE 31 TONIGHT. ACROSS PLAINS...SOUTHERLY WINDS AND
A BIT OF WARM AIR ADVECTION SHOULD DRIVE TEMPERATURES CLOSE TO 60
DEGREES. BUT LATEST WRF SYNTHETIC SATELLITE IMAGERY INDICATING
SOME INCREASE IN MID AND HIGH LEVEL MOISTURE WHICH COULD HINDER
WARMUP. MAY NEED TO SHAVE A FEW DEGREES OFF THE MAX TEMP GRIDS BUT
WILL WAIT TO SEE WHAT DEVELOPS. PERHAPS A FEW SHOWERS THIS EVENING
ALONG THE WYOMING AND NEBRASKA BORDERS AS SOME MID LEVEL ASCENT
MOVES ACROSS WYOMING.
.AVIATION...WEAK CONVERGENCE ZONE HAS DEVELOPED FROM NORTHEAST OF
DIA TO NORTHERN ELBERT COUNTY...WITH WEAK WEST TO NORTHWEST WINDS
AT KDEN...SOUTHWEST AT KAPA AND NORTHWEST AT KBJC. WINDS APPEARS
THIS ZONE IS SLOWLY SHIFTING EAST...WOULD EXPECT WINDS AT KDEN TO
BECOME A BIT MORE NORTHERLY BY 18Z...THEN NORTHEAST TO EAST DURING
THE AFTERNOON. WILL TREND KAPA MORE SOUTHWEST THROUGH THE
AFTERNOON...KEEPING LIGHT NORTHWEST WINDS AT KBJC. REST OF TAF
TRENDS SEEM ON TRACK. LATEST RAP STILL INDICATING SOME SORT OF A
WESTERLY BOUNDARY MOVING ACROSS THE DENVER AREA BETWEEN 21Z AND
00Z. THIS STILL SEEMS REASONABLE AS SOME MIXING COULD
OCCUR BUT WILL LOWER SPEEDS A BIT.
&&
.PREV DISCUSSION... /ISSUED 322 AM MDT WED MAR 20 2013/
SHORT TERM...THE FLOW ALOFT WILL BECOME MORE WLY TODAY AND
TONIGHT AS MOISTURE GRADUALLY INCREASES IN THE MTNS BY LATER THIS
AFTN AND EVENING. THERE IS VERY LITTLE MID LVL ASCENT WITH LAPSE
RATES ON AVERAGE AROUND 6 C/KM. SHOULD SEE SNOW INCREASE IN ZN 31
LATE THIS AFTN AND ACROSS THE REST OF THE MTNS THIS EVENING.
AMOUNTS THRU 12Z THU LOOK TO BE BLO ADVISORY CRITERIA EXCEPT
POSSIBLY IN ZN 31.
OVER NERN CO SURFACE HIGH PRES WILL MOVE INTO THE CNTRL US AS SFC
LOW PRES DEVELOPS OVER ERN CO BY AFTN. THUS WILL SEE INCREASING
SOUTH WINDS OVER THE PLAINS BY AFTN. ALTHOUGH THERE WILL BY AN
INCREASE IN MID AND HIGH CLOUDS AT THIS TIME IT LOOKS DRY THRU THE
AFTN HOURS. HIGHS THIS AFTN WILL RISE INTO THE UPPER 50S TO LOWER
60S OVER NERN CO EXCEPT POSSIBLE OVER THE FAR NERN CORNER WHERE
READINGS WILL BE SLIGHTLY LOWER. FOR TONIGHT MAY SEE A SLIGHT CHC
OF SHOWERS NR THE WY-NE BORDER SO WILL KEEP IN LOW POPHE TREND WOULD BE TO
S IN THESE AREAS.
LONG TERM...FOR THURSDAY...THERE WILL BE A FAST MOVING EMBEDDED
WAVE IN THE NORTHWEST FLOW PATTERN. THIS WAVE WILL BENEFIT THE
MOUNTAINS THE MOST WITH DECENT OROGRAPHIC FLOW AND STEEPENING
LAPSE RATES BY THURSDAY AFTERNOON. THERE WILL STILL BE A CHANCE OF
SHOWERS OVER THE NORTHEAST PLAINS...BUT DOWNSLOPE NORTHWEST WINDS
WILL LIMIT SHOWER POTENTIAL OVER THE FRONT RANGE. BEST CHANCE WILL
LIKELY BE FURTHER EAST AWAY FROM THE MOUNTAINS. SUBSIDENCE QUICKLY
MOVES IN BEHIND THE WAVE THURSDAY EVENING WITH PRECIP ENDING AND
CLEARING SKIES AND DECREASING WINDS. STILL SOME SNOW SHOWERS IN
THE MOUNTAINS THURSDAY EVENING BEFORE LAPSE RATES STABILIZE AND
MOISTURE BECOMES QUITE SHALLOW.
ATTENTION THEN SHIFTS TOWARDS STRONGER STORM SYSTEM WHICH IS
EXPECTED TO DEVELOP OVER THE NORTHERN GREAT BASIN ON FRIDAY BEFORE
MOVING ACROSS COLORADO ON SATURDAY. YET AGAIN...LONG RANGE MODELS
HAVE TRENDED BACK AWAY FROM THE CLOSED LOW SOLUTION TO A MORE
PROGRESSIVE AND FASTER OPEN WAVE. THE GFS IS NOW THE FASTEST
WHILE THE CANADIAN IS SLOWEST WHILE STILL HOLDING ON TO A CLOSED
LOW NEAR THE 4 CORNERS BY MIDDAY SATURDAY. MOST OF THE GFS
ENSEMBLE MEMBERS SUPPORT THE FASTER MOVING SOLUTION. REGARDLESS OF
EXACT TRACK THERE STILL IS CERTAINLY THE POTENTIAL FOR IMPACT
WINTER WEATHER ON SATURDAY IN THE REGION. NOT MUCH CHANGE TO
ONGOING FORECAST BASED ON MODEL INCONSISTENCIES.
FOR SUNDAY AND MONDAY...MAINLY DRY SUNDAY BUT ANOTHER WEAKER
CLOSED LOW FEATURE OVER THE NORTHERN ROCKIES SLIDES A PIECE OF
ENERGY INTO COLORADO LATE SUNDAY AND MONDAY FOR ANOTHER CHANCE OF
SNOW OVER MUCH OF THE STATE. TEMPERATURES WILL BE BELOW NORMAL FOR
MUCH OF THIS EXTENDED PERIOD.
AVIATION...WINDS HAVE BECOME LIGHT SLY EARLY THIS MORNING. BOTH
THE HRRR AND RAP SHOW WINDS BECOMING MORE ELY BY MIDDAY. BY LATE
AFTN THERE ARE SOME INDICATIONS THE STRONGER WLY FLOW ALOFT WILL
MIX DOWN TO THE SFC AS A BNDRY COMES OFF THE FOOTHILLS WITH WINDS
BECOMING WLY IN THE 23Z-00Z TIMEFRAME AND CONTINUING THRU THE
EARLY EVENING HOURS. BY MID EVENING WINDS SHOULD BECOME MORE SSW
AND CONTINUE OVERNIGHT. VFR CONDITIONS WILL BE IN PLACE THRU THE
PERIOD WITH ONLY SOME MID AND HIGH LVL CLOUD COVER THIS AFTN AND
TONIGHT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....ENTREKIN
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
322 AM MDT WED MAR 20 2013
.SHORT TERM...THE FLOW ALOFT WILL BECOME MORE WLY TODAY AND
TONIGHT AS MOISTURE GRADUALLY INCREASES IN THE MTNS BY LATER THIS
AFTN AND EVENING. THERE IS VERY LITTLE MID LVL ASCENT WITH LAPSE
RATES ON AVERAGE AROUND 6 C/KM. SHOULD SEE SNOW INCREASE IN ZN 31
LATE THIS AFTN AND ACROSS THE REST OF THE MTNS THIS EVENING.
AMOUNTS THRU 12Z THU LOOK TO BE BLO ADVISORY CRITERIA EXCEPT
POSSIBLY IN ZN 31.
OVER NERN CO SURFACE HIGH PRES WILL MOVE INTO THE CNTRL US AS SFC
LOW PRES DEVELOPS OVER ERN CO BY AFTN. THUS WILL SEE INCREASING
SOUTH WINDS OVER THE PLAINS BY AFTN. ALTHOUGH THERE WILL BY AN
INCREASE IN MID AND HIGH CLOUDS AT THIS TIME IT LOOKS DRY THRU THE
AFTN HOURS. HIGHS THIS AFTN WILL RISE INTO THE UPPER 50S TO LOWER
60S OVER NERN CO EXCEPT POSSIBLE OVER THE FAR NERN CORNER WHERE
READINGS WILL BE SLIGHTLY LOWER. FOR TONIGHT MAY SEE A SLIGHT CHC
OF SHOWERS NR THE WY-NE BORDER SO WILL KEEP IN LOW POPHE TREND WOULD BE TO
S IN THESE AREAS.
.LONG TERM...FOR THURSDAY...THERE WILL BE A FAST MOVING EMBEDDED
WAVE IN THE NORTHWEST FLOW PATTERN. THIS WAVE WILL BENEFIT THE
MOUNTAINS THE MOST WITH DECENT OROGRAPHIC FLOW AND STEEPENING
LAPSE RATES BY THURSDAY AFTERNOON. THERE WILL STILL BE A CHANCE OF
SHOWERS OVER THE NORTHEAST PLAINS...BUT DOWNSLOPE NORTHWEST WINDS
WILL LIMIT SHOWER POTENTIAL OVER THE FRONT RANGE. BEST CHANCE WILL
LIKELY BE FURTHER EAST AWAY FROM THE MOUNTAINS. SUBSIDENCE QUICKLY
MOVES IN BEHIND THE WAVE THURSDAY EVENING WITH PRECIP ENDING AND
CLEARING SKIES AND DECREASING WINDS. STILL SOME SNOW SHOWERS IN
THE MOUNTAINS THURSDAY EVENING BEFORE LAPSE RATES STABILIZE AND
MOISTURE BECOMES QUITE SHALLOW.
ATTENTION THEN SHIFTS TOWARDS STRONGER STORM SYSTEM WHICH IS
EXPECTED TO DEVELOP OVER THE NORTHERN GREAT BASIN ON FRIDAY BEFORE
MOVING ACROSS COLORADO ON SATURDAY. YET AGAIN...LONG RANGE MODELS
HAVE TRENDED BACK AWAY FROM THE CLOSED LOW SOLUTION TO A MORE
PROGRESSIVE AND FASTER OPEN WAVE. THE GFS IS NOW THE FASTEST
WHILE THE CANADIAN IS SLOWEST WHILE STILL HOLDING ON TO A CLOSED
LOW NEAR THE 4 CORNERS BY MIDDAY SATURDAY. MOST OF THE GFS
ENSEMBLE MEMBERS SUPPORT THE FASTER MOVING SOLUTION. REGARDLESS OF
EXACT TRACK THERE STILL IS CERTAINLY THE POTENTIAL FOR IMPACT
WINTER WEATHER ON SATURDAY IN THE REGION. NOT MUCH CHANGE TO
ONGOING FORECAST BASED ON MODEL INCONSISTENCIES.
FOR SUNDAY AND MONDAY...MAINLY DRY SUNDAY BUT ANOTHER WEAKER
CLOSED LOW FEATURE OVER THE NORTHERN ROCKIES SLIDES A PIECE OF
ENERGY INTO COLORADO LATE SUNDAY AND MONDAY FOR ANOTHER CHANCE OF
SNOW OVER MUCH OF THE STATE. TEMPERATURES WILL BE BELOW NORMAL FOR
MUCH OF THIS EXTENDED PERIOD.
&&
.AVIATION...WINDS HAVE BECOME LIGHT SLY EARLY THIS MORNING. BOTH
THE HRRR AND RAP SHOW WINDS BECOMING MORE ELY BY MIDDAY. BY LATE
AFTN THERE ARE SOME INDICATIONS THE STRONGER WLY FLOW ALOFT WILL
MIX DOWN TO THE SFC AS A BNDRY COMES OFF THE FOOTHILLS WITH WINDS
BECOMING WLY IN THE 23Z-00Z TIMEFRAME AND CONTINUING THRU THE
EARLY EVENING HOURS. BY MID EVENING WINDS SHOULD BECOME MORE SSW
AND CONTINUE OVERNIGHT. VFR CONDITIONS WILL BE IN PLACE THRU THE
PERIOD WITH ONLY SOME MID AND HIGH LVL CLOUD COVER THIS AFTN AND
TONIGHT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....ENTREKIN
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
909 AM EDT WED MAR 20 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM WELL TO OUR NORTH WILL TRACK INTO THE CANADIAN
MARITIMES TODAY, WITH A COLD FRONT CROSSING OUR REGION LATE TODAY
AND INTO TONIGHT. MEANWHILE, ANOTHER LOW PRESSURE SYSTEM WILL EMERGE
OFF THE SOUTHEASTERN SEABOARD TONIGHT AND INTENSIFY AS IT TRACKS
WELL OFF THE MID ATLANTIC COAST THROUGH THURSDAY. HIGH PRESSURE IS
THEN FORECAST TO INFLUENCE OUR REGION FRIDAY THROUGH SUNDAY. FOR
EARLY NEXT WEEK, A COASTAL LOW MAY AFFECT THE AREA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
BASED ON THE 12Z SOUNDING FULL SUN MACROS, WE BUMPED UP MAX
TEMPERATURES SLIGHTLY. BASED ON THE LATEST HRRR AND ONGOING
ECHOES, WE FILLED IN THE GAP OF FLURRIES IN THE POCONOS.
OTHERWISE, THE REST OF THE FORECAST REMAINS CLOSE AND NO OTHER BIG
CHANGES WERE MADE.
AFTER A SUNNY BRISK START WITH WESTERLY WINDS GUSTING 25 TO 30 MPH
THROUGH MID AFTERNOON...SKIES CLOUD UP RAPIDLY BETWEEN 6 AND 10000
FT VERY LATE IN THE AFTN (5PM IN RESPONSE TO FGEN AHEAD OF OUR
FORMING COLD FRONT). WINDS BELOW 950 MB TURN SSW AND INCREASE ALONG
THE DELMARVA WITH MOISTURE ADVECTION BY EVENING.
TEMPS/WINDS ARE 50 50 BLENDED 00Z/20 NAM/GFS MOS GUIDANCE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
YOU`VE SEEN THE FAR TOO ROBUST NAM QPF FROM THE 06Z CYCLE...
NEVERTHELESS THE MODEL IS CUING FOR WHAT I THINK SHOULD BE 2 NICE
SNOW SHOWER BANDS. THE FIRST MAY BE TOO WARM TO SUPPORT MUCH SNOW
ACCUM PRIOR TO 05Z EXPECT MAYBE CHESTER COUNTY. THE LATTER TWD 10Z
MAY BE MORE PRODUCTIVE NEAR THE S OR CENTRAL NJ COAST.
COULD BE AN INTERESTING HOUR OR TWO DURING THE NIGHT IN AN AXIS
FROM KPHL TO KNEL OR SLIGHTLY FURTHER SOUTH. AXIS OF HIGH TT AND KI
(MID 50S AND MID 20S RESPECTIVELY) REFLECTS FGEN MOISTENING A FAIRLY
STEEP LOW LVL LAPSE RATE THAT SHOULD PRODUCE TWO NE-SW BANDS OF LIGHT
TO MDT SNOW SHOWERS. WHILE THE INITIAL SNOWFALL SHOULD MELT ON CONTACT...I
DO THINK THERE WILL BE AN ACCUMULATION. ITS SNOW SHOWERS...SO
WHERE THE BANDS ARE MOST PRODUCTIVE IS NOT EASY TO BE SURE OF BUT
THINK THAT MANY OF US FROM SE PA INTO NJ AND POSSIBLY N DE WILL
AWAKE THURSDAY MORNING TO A FRESH COVER OF SNOW WITH POTENTIAL FOR
ROAD TREATMENTS. TWO DAYS AGO...THIS LOOKED TO BE BEST FIT FOR THE
HIGHER TERRAIN OF E PA BUT TRENDS HAVE BEEN SEWD AND SO...IT APPEARS
TO ME THAT CENTRAL OR SNJ IS A BEST FIT FOR VARIABLE AMOUNTS OF
1/2 TO 1 INCH SNOW ON GRASS...POTENTIAL EXISTING FOR 2 INCH AMTS IN A
COUPLE OF LOCATIONS. PAVEMENT LESS BUT PAVEMENT CAN BECOME SLIPPERY
FM THIS LATER ON IF THE READ ON THE CONVECTIVE NATURE IS CORRECT.
FCST TEMPERATURES/WINDS WERE A STRAIGHT 50 50 BLEND OF THE 00Z/20
NCEP MOS.
FOR THIS TO BE A FAILED FCST LOOK FOR THE FUTURE 12Z/20 NAM AND GFS
TO QUIT GENERATING PCPN FOR THIS COMING NIGHT. IF THE MODELED
AMOUNTS ARE JUST .01 OR .03 THEN ITS NOT GOING TO BE MUCH IF
ANYTHING AT ALL. BUT...IF THE MODEL AMTS CONTINUE TO ADVERTISE A
12 HOUR TOTAL OF .1 OR GREATER...THEN WE ARE IN BUSINESS.
FOR THOSE WHO LOOK AT OTHER MODELS...MYSELF..I EXPERIENCE MORE
SUCCESS USING THE NCEP MODELS IN QPF GENERATION FOR CONVECTIVE
TYPE EVENTS.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
TO START THE LONG TERM, A WEAK LOW IS PROGGED TO BE NEAR THE MID
ATLANTIC REGION, WITH MID-LEVEL TROUGHING BACK OVER THE
APPALACHIANS. THIS WEAK LOW IS FORECAST TO MERGE WITH A MUCH
STRONGER AREA OF LOW PRESSURE THAT WILL BE ADVANCING NORTHEASTWARD
WELL OFF THE MID ATLANTIC COAST DURING THURSDAY. OVERALL MOISTURE
AND LIFT ASSOCIATED WITH THE WEAK LOW NEAR THE MID ATLANTIC THURSDAY
MORNING ARE NOT OVERLY IMPRESSIVE, BUT WE DID RETAIN SLIGHT CHANCE
POPS FOR LIGHT RAIN/SNOW ACROSS MUCH OF THE REGION FOR A TIME.
RELATIVELY QUIET WEATHER IS THEN EXPECTED FROM FRIDAY THROUGH SUNDAY
AS HIGH PRESSURE FROM CENTRAL CANADA INFLUENCES OUR REGION. A RATHER
COOL NORTHWEST FLOW ALOFT WITH A MID-LEVEL LOW REMAINING PRESENT TO
OUR NORTH THROUGH THIS TIMEFRAME WILL KEEP CONDITIONS ON THE COOL
SIDE WITH TEMPERATURES RUNNING BELOW MID TO LATE MARCH AVERAGES.
GOING INTO EARLY NEXT WEEK, THE GFS AND ECMWF BOTH SHOW DEVELOPING
LOW PRESSURE IN THE OHIO VALLEY. A SECONDARY COASTAL LOW IS ALSO
FORECAST TO EMERGE OFF THE SOUTHEASTERN SEABOARD SUNDAY AFTERNOON
AND SUBSEQUENTLY TRACK NORTHEAST NEAR THE MID ATLANTIC COAST SUNDAY
NIGHT INTO MONDAY BEFORE MOVING OUT TO SEA MONDAY NIGHT. DIFFERENCES
REMAIN AT THIS EXTENDED TIMEFRAME REGARDING THE TRACK AND INTENSITY
OF THESE LOW PRESSURE SYSTEMS, WITH THE GFS GENERALLY SHOWING
STRONGER SURFACE LOWS. THERMAL FIELDS ALSO DIFFER BETWEEN THE
MODELS, AND THIS LOOKS TO BE ANOTHER MIXED RAIN/SNOW EVENT, WITH THE
GREATEST CHANCES FOR MORE IN THE WAY OF FROZEN PRECIPITATION BEING
ACROSS OUR NORTHWEST ZONES. OVERALL, THIS WILL BE THE NEXT
POTENTIALLY SIGNIFICANT SYSTEM ON THE HORIZON TO WATCH, AND OVER THE
NEXT FEW DAYS, THE DETAILS OF PRECIP TYPE AS WELL AS TIMING CAN BE
IRONED OUT AS THE MODELS COME TO CLOSER AGREEMENT.
&&
.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
AFTER 12Z...VFR WITH W GUSTS TO NEAR 25 KT. WINDS BACK LATE IN
THE DAY AND DIMINISH WITH VFR CIGS FORMING BETWEEN 6000 AND 10000
FT NEAR 21Z.
TONIGHT...CIGS LOWER TO 5000 FT MOST TAF LOCATIONS WITH A PERIOD
OF MVFR OR IFR CONDS PROBABLE FOR KILG/KPHL/KPNE/KTTN/KACY/KMIV
IN SNOW SHOWERS. BEST WINDOW OF OPPORTUNITY APPEARS TO BE AFTER
05Z.
LIGHT WINDS BECOMING N 10-15 KTS BY MORNING.
OUTLOOK...
THURSDAY...POSSIBLE MVFR AND LEFTOVER LIGHT SNOW SHOWERS DURING
THE MORNING, WITH IMPROVEMENT TO VFR FROM WEST TO EAST DURING THE
AFTERNOON.
FRIDAY THROUGH SATURDAY...MAINLY VFR CONDITIONS.
SUNDAY...MAINLY VFR. CONDITIONS MAY BEGIN TO LOWER SUNDAY NIGHT WITH
POSSIBLE RAIN/SNOW.
&&
.MARINE...
CONVERTED GALE TO SCA CONDS TODAY. COULD HAVE ISOLATED GALE GUST
DURING MIDDAY BUT ITS NOT WORTH A GALE WARNING... JUST APPEARS TOO
DIFFICULT TO ACHIEVE MULTIPLE HOUR GALE GUSTS TODAY AT ANY ONE
LOCATION.
TONIGHT...NO HEADLINE ANTICIPATED. WINDS EAST OF DE AND AND S NJ
BECOME SSW G 20 KTS FOR A TIME WHILE ELSEWHERE WINDS SHOULD BECOME
LIGHT. THEN ALL AREAS SHIFT TO THE N BY 8AM THURSDAY WITH G TO 20
KTS.
THERE IS A SMALL CHANCE FOR G 25 KTS OFF THE DE WATERS NEAR 12Z
THU.
OUTLOOK...
SCA CONDITIONS MAY BE POSSIBLE FOR A TIME ON THURSDAY WITH GUSTY
WEST TO NORTHWEST WINDS AS AN INTENSIFYING LOW PRESSURE SYSTEM MOVES
WELL OFF THE MID ATLANTIC COAST. FROM FRIDAY AND INTO THE WEEKEND,
CONDITIONS ARE EXPECTED TO BE BELOW SCA CRITERIA AS HIGH PRESSURE
INFLUENCES THE REGION. EARLY NEXT WEEK, A COASTAL LOW MAY AFFECT
THE AREA WATERS.
&&
.FIRE WEATHER...
WE CONTACTED NJ FORESTRY AND NON 10 HR FUELS REMAIN TOO WET FOR THE
RAPID SPREAD OF WILDFIRES.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ430-
431-450>455.
&&
$$
SYNOPSIS...KLINE
NEAR TERM...DRAG/GIGI
SHORT TERM...DRAG
LONG TERM...KLINE
AVIATION...DRAG/KLINE
MARINE...DRAG/KLINE
FIRE WEATHER...GIGI
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
340 PM EDT WED MAR 20 2013
.SHORT TERM (TONIGHT-FRIDAY)...
FOR THE REST OF THIS AFTERNOON...SHOWERS WITH A FEW THUNDERSTORMS
SHOULD BE MOVING OVER THE AREA AS THE CONVECTION IN THE GULF KICKS
OUT WITH THE NEXT UPPER DISTURBANCE. THE WEAK SURFACE LOW OVER THE
PENINSULA SHOULD ALSO CONTINUE TO LIFT E/NE TO OVER THE ATLANTIC
AND DRAG A COLD FRONT THROUGH THE AREA. THE SHOWERS AND
THUNDERSTORMS SHOULD CLEAR QUICKLY OUT OF THE AREA AROUND
00Z...BUT HAVE KEPT 20 PERCENT CHANCES IN THROUGH 06Z AS ITS
DEPENDENT ON HOW STRONG A PUSH THE NEXT BAND OF ENERGY HAS ONCE IT
INTERACTS WITH THE CONVECTION THAT HAS BEEN STREAMING CLOUDS AND
SOME STRATIFORM RAIN ACROSS THE AREA THROUGH THE DAY. WILL BE
PUTTING A PRE-FIRST PERIOD INTO THE ZONES TO SHOW THE CONTINUING
LATE AFTERNOON EXPECTED HIGH RAIN CHANCES. WINDS QUICKLY SHIFT
AROUND TO THE SE FOR FRIDAY ALLOWING FOR SOME MOISTURE RETURN AS
HIGH PRESSURE CONTINUES TO RIDGE ACROSS THE AREA. WITH THE
MOISTURE RETURN HAVE ADDED AN AFTERNOON 20 PERCENT RAIN CHANCE.
TEMPERATURES TONIGHT WILL BE IN THE LOWER 40S NORTH...AND IN THE
UPPER 40S TO MID 50S ELSEWHERE. THURSDAY HIGHS WILL BE IN THE MID
60S NORTH AND COASTAL TO THE MID 70S SOUTH. THURSDAY NIGHT WILL
FALL INTO THE MID 30S NORTH TO THE LOWER 40S TO LOWER 50S CENTRAL
AND SOUTH. AND HIGHS FRIDAY WILL BE WARMING TO THE LOWER 70S NORTH
TO THE LOWER 80S SOUTH.
.LONG TERM (FRIDAY NIGHT-TUESDAY)...
THE LONG TERM PERIOD BEGINS FRIDAY NIGHT WITH SURFACE HIGH
PRESSURE OFF THE EAST COAST OF FLORIDA SLIDING FARTHER EAST.
MEANWHILE A REMNANT FRONTAL BOUNDARY WILL MOVE BACK NORTH THROUGH
FLORIDA AND THE EASTERN GULF AS A WARM FRONT BRINGS WINDS BACK
AROUND TO THE SOUTH. A SHORTWAVE PASSING ALONG THE NORTHERN GULF
COAST SATURDAY AND SATURDAY NIGHT WILL TAKE ADVANTAGE OF THE
SURFACE BOUNDARY AND MOIST SOUTHERLY LOW LEVEL WINDS TO FUEL
SHOWERS AND THUNDERSTORMS OVER THE NORTHERN HALF OF THE AREA.
BEFORE RAIN CHANCES GET AN OPPORTUNITY TO SUBSIDE...A COLD FRONT
ASSOCIATED WITH MID LEVEL TROUGHING WILL MOVE ACROSS THE AREA
SUNDAY AND SUNDAY NIGHT WITH ANOTHER WAVE OF CHANCE POPS MOVING
ACROSS THE ENTIRE AREA. THE FRONT WILL STALL OVER SOUTH FLORIDA
WITH SLIGHT CHANCE (20 PERCENT) POPS LINGERING OVER SOUTHERN AND
CENTRAL FLORIDA THROUGH THE EARLY PART OF THE WEEK.
TEMPERATURES WILL GET A CHANCE TO WARM UP TO SEVERAL DEGREES ABOVE
NORMAL THIS WEEKEND AHEAD OF THE COLD FRONT. MIN TEMPS WILL COOL
OFF SOMEWHAT MONDAY NIGHT WITH LOWS IN THE MID TO UPPER 40S ALONG
THE NATURE COAST...MID 50S OVER CENTRAL FLORIDA...AND AROUND 60
OVER SOUTHWEST FLORIDA.
OVERALL...ECMWF IS A TOUCH FASTER THAN GFS THROUGH THE ENTIRE LONG
TERM PERIOD ESPECIALLY WITH THE COLD FRONT LATE THIS WEEKEND. FOR
THE POPS AND TEMPERATURES...WEIGHTED THIS FORECAST PACKAGE MORE
TOWARDS GFS...BUT BLENDED IN THE ECMWF AS WELL TO STAY ON THE SAFE
SIDE.
&&
.AVIATION...
TIMING OF RAIN AND STORMS CONTINUES TO BE A HUGE PROBLEM AS
MODELS ARE STRUGGLING MIGHTILY WITH THE DETAILS OF TODAY`S
FORECAST. TIMING OF MORE SIGNIFICANT PRECIP AND TSTMS ON THE 18Z
TAFS WAS BASED PARTLY ON RADAR TRENDS THE HOUR BEFORE...BUT SINCE
THEN...STORMS HAVE WEAKENED AND DECREASED IN COVERAGE ACROSS THE
NEARSHORE WATERS. MORE AND MORE...IT APPEARS THE MAIN PRECIP/TSTM
EVENT TODAY IS GOING OCCUR WITH THE LAST MAIN S/WV WHICH IS
CURRENTLY GENERATING A SQUALL LINE SOUTH OF MOB. THIS LINE IS
RACING ESE ACROSS THE GULF. WHAT IS LEFT OF THE LINE WILL IMPACT W
AND SW FL ROUGHLY BETWEEN 22 AND 2Z WHICH IS THE TIME FRAME THE
LATEST RAP IS HINTING AT AS WELL. BASED ON THIS WILL BE UPDATING
THE TAFS TO MOVE BACK PRECIP TIMING MORE IN LINE WITH THIS
THINKING. AFTER MVFR CONDITIONS ASSOC W/ THE SHRA AND TSTMS MOVES
OUT OF THE AREA... EXPECT IMPROVING CONDITIONS OVERNIGHT WITH VFR
CONDITIONS DEVELOPING AS COOL AND DRY AIR MOVES INTO THE REGION
BEHIND A COLD FRONT.
&&
.MARINE...
WINDS AND SEAS ARE EXPECTED TO INCREASE TO SCA CONDITIONS ACROSS
THE NORTHERN AND CENTRAL OFFSHORE WATERS BEHIND THE FRONT THIS
EVENING AS HIGH PRESSURE BEGINS TO BUILD INTO THE AREA. HIGH
PRESSURE THEN REMAINS ACROSS THE WATERS THROUGH SATURDAY NIGHT
WITH WINDS DIMINISHING BY MID THURSDAY MORNING. THE NEXT COLD
FRONT WILL THEN PUSH INTO THE AREA FOR SUNDAY WITH WINDS AND SEAS
INCREASING AGAIN JUST AHEAD OF THE FRONT.
&&
.FIRE WEATHER...
COOLER AND DRIER AIR WILL BE MOVING INTO THE AREA BEHIND THE FRONT
TONIGHT ALLOWING FOR SEVERAL HOURS OF CRITICAL HUMIDITIES THURSDAY
AFTERNOON. WINDS SHOULD BE LIGHT AND ERCS LOW ENOUGH TO PREVENT
ANY NEED FOR A RFW OR RFD. MOISTURE WILL BE RETURNING FRIDAY...BUT
A FEW HOURS OF CRITICAL HUMIDITIES WILL STILL BE POSSIBLE. WILL
CONTINUE TO MONITOR ERC VALUES BUT WINDS SHOULD BE LIGHT AGAIN.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 50 67 48 75 / 20 0 0 20
FMY 56 74 52 81 / 20 0 0 20
GIF 50 71 48 78 / 20 0 0 20
SRQ 54 67 48 75 / 20 0 0 20
BKV 41 67 34 77 / 20 0 0 20
SPG 57 66 55 74 / 20 0 0 20
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 10 AM EDT
THURSDAY FOR ENGLEWOOD TO TARPON SPRINGS OUT 20 TO 60
NM-TARPON SPRINGS TO SUWANNEE RIVER OUT 20 TO 60 NM.
&&
$$
SHORT TERM/MARINE/FIRE WEATHER...24/COLSON
LONG TERM/AVIATION...88/GITTINGER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
224 PM MDT WED MAR 20 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 224 PM MDT WED MAR 20 2013
19Z WATER VAPOR IMAGERY RUC ANALYSIS INDICATED SHORT WAVE RIDGE
ACROSS NORTHERN PLAINS WITH STRONG TROUGH OVER THE PAC NW. AT THE
SFC...TROUGH WAS DEEPENING OVER EASTERN COLORADO WITH STRONG
SOUTH WINDS DEVELOPING ACROSS MUCH OF THE AREA. THICK CIRRUS HAS
SLOWED WARMING DOWN CONSIDERABLY BUT THINK TEMPS WILL EVENTUALLY
CLIMB INTO LOWER/MID 50S AS WINDS AID IN DEEP LAYER MIXING.
TONIGHT...WEAK SHORT WAVE TROUGH WILL UNDERCUT H5 RIDGE TONIGHT AS
STRONG WAA DEVELOPS TO THE NORTH OF DEVELOPING WARM FRONT ACROSS
NORTHERN CWA. HAVE SOME CONCERNS THAT LIGHT PRECIP MAY CLIP THE
NORTHEASTERN CWA IN AREA OF DEEP WAA...BUT VERTICAL PROFILES APPEAR
TO STABLE TO PRODUCE PRECIPITATION RATES NEEDED TO SATURATE SUB
CLOUD LAYER. PROBABILISTIC DATA SEEMS TO SUPPORT ANY PRECIP THREAT
REMAINING NORTH OF AREA AS WELL SO PLAN ON CONTINUING DRY FORECAST.
WILL HAVE TO WATCH UPSTREAM PRECIP POTENTIAL CLOSELY THOUGH AS WARM
LAYER AOB 3C THROUGH MUCH OF THE NIGHT WHICH WOULD REMOVE ANY ICE
FROM SOUNDING INITIALLY ALLOWING FOR RA/FZRA/IP TO FORM IF PRECIP
WERE TO OCCUR. AS MENTIONED BEFORE THIS REMAINS A VERY LOW
PROBABILITY AT THIS TIME AND IF PRECIP WERE TO OCCUR WET BULB
PROCESSES WOULD COOL WARM LAYER QUICKLY RESULTING IN A FAIRLY SHORT
DURATION.
TOMORROW...A FEW AREAS OF MORNING FOG EXPECTED AS WINDS SHIFT TO THE
EAST IN RESPONSE TO NEXT...MORE SIGNIFICANT SHORT WAVE TROUGH MOVING
INTO THE NORTHERN ROCKIES. THINK WEATHER ACROSS CWA WILL BE FAIRLY
QUIET THROUGH MUCH OF THE DAY...ALTHOUGH PRECIP THREAT WILL BEGIN TO
INCREASE IN THE AFTERNOON AS LARGE SCALE FORCING FOR ASCENT
INCREASES AND CAA ALOFT HELPS DESTABILIZE THINGS. DO NOT THINK
STABILITY PROFILES SUPPORT A THUNDER THREAT ATTM AND PLAN ON KEEPING
PRECIP TYPE AS RAIN THROUGH THE DAY.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 224 PM MDT WED MAR 20 2013
FIRST 500 MB SHORT WAVE WILL MOVE ACROSS THE HIGH PLAINS THURSDAY
NIGHT...THOUGH BEST ENERGY IS PROGGED TO BE NORTH OF THE FORECAST
AREA. INVERTED SURFACE TROUGH WILL PROVIDE LOW LEVEL CONVERGENCE
FROM GOODLAND TO MCCOOK. HOWEVER...MODEL SOUNDINGS SHOW THAT THE
AIR MASS WILL BE SLOW TO SATURATE BELOW 700 MB...ESPECIALLY OVER
THE EASTERN PART OF THE FORECAST AREA. LAYER Q VECTOR CONVERGENCE
IS ALSO NOT PARTICULARLY IMPRESSIVE...THOUGH LOW LEVEL
FRONTOGENESIS IS A LITTLE BETTER FROM 00Z-06Z. BOTTOM LINE ON THIS
FIRST WAVE...WILL CARRY POPS THROUGH 06Z WITH DECREASING CHANCES
AFTERWARDS. MOST PRECIPITATION WILL BE IN THE FORM OF RAIN...THOUGH
COLD AIR WILL EVENTUALLY ADVECT OVER THE AREA AFTER 06Z. AGAIN...THOUGH
...BEST DYNAMICS WILL BE EAST OF THE AREA BY THAT TIME...SO DO
NOT EXPECT MUCH SNOW ACCUMULATION.
THE FIRST SYSTEM WILL MOVE EAST FRIDAY...BUT THE NEXT MORE VIGOROUS
WAVE WILL MOVE OVER EASTERN COLORADO BY FRIDAY AFTERNOON. THIS
SYSTEM IS PROGGED TO HAVE EXCELLENT GEOSTROPHIC PARAMETERS THROUGH
SATURDAY TO PRODUCE WIDESPREAD PRECIPITATION. THE BEST WINDOW FOR
PRECIPITATION WILL OCCUR FROM 09Z SATURDAY THROUGH 03Z SUNDAY. BY
12Z SATURDAY...COLD AIR ADVECTION WILL BE OVER THE ENTIRE AREA...SO
EXPECT PRECIPITATION TYPE TO BE ALL SNOW SATURDAY. PROJECTED SNOW
TOTALS RANGE FROM TWO INCHES SOUTH TO SEVEN INCHES NORTH. THESE
PROJECTIONS ARE IN LINE WITH WINTER SEASON ANALOGS AND WPC ESTIMATES.
MODELS AND OTHER EXTERNAL GUIDANCE HAVE SHOWN DECENT RUN-TO-RUN
CONSISTENCY WITH THIS SYSTEM. NORTH WINDS AT 20 TO 30 KNOTS WILL
DEVELOP SATURDAY PRODUCING AREAS OF BLOWING SNOW.
THE SYSTEM WILL MOVE EAST SUNDAY...BUT WILL KEEP SOME LOW POPS OVER
THE EASTERN THIRD. YET ANOTHER SHORT WAVE TROUGH WILL MOVE OVER THE
HIGH PLAINS SUNDAY NIGHT AND MONDAY BRINGING ANOTHER CHANCE OF
PRECIPITATION. FOR TUESDAY AND WEDNESDAY...MODELS DIVERGE. FOR NOW...
WILL KEEP THE FORECAST DRY.
TEMPERATURES WILL BE SIGNIFICANTLY BELOW NORMAL FRIDAY THROUGH
MONDAY GIVEN ABUNDANT CLOUD COVER...SNOW...AND THE AMOUNT OF COLD
AIR WITH THE SYSTEM. MODELS SHOW WARMING TUESDAY AND WEDNESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1142 AM MDT WED MAR 20 2013
SOUTHERLY WINDS WILL INCREASE TO THE 16-22KT RANGE THROUGH THE
AFTERNOON HOURS FIRST AT GLD AND THEN GRADUALLY EXPANDING TO THE
EAST IMPACTING MCK TO SOME DEGREES AROUND 20Z. WEAK DISTURBANCE
WILL MOVE OVER THE MCK AREA DURING THE EVENING HOURS...BUT
CONFIDENCE IN PRECIPITATION DEVELOPING TOO LOW AT THIS POINT TO
INCLUDE IN TERMINAL BUT GIVEN WARM +3C ALOFT THERE IS POTENTIAL
FOR RA/FZRA SHOULD PRECIP DEVELOP. OTHERWISE WITH WINDS SHIFTING
TO THE EAST AND LOW LEVEL ASCENT LINGERING THROUGH THE MORNING
HOURS...POTENTIAL DOES EXIST FOR MORNING STRATUS AND FOG ALTHOUGH
CURRENT CONFIDENCE LEVELS ARE LOW SO HAVE ONLY INCLUDED MINOR
FLIGHT CATEGORY REDUCTIONS WHERE CONFIDENCE IS HIGHEST.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JRM
LONG TERM...MENTZER
AVIATION...JRM
AREA FORECAST DISCUSSION
NWS PADUCAH KY
850 PM CDT THU MAR 21 2013
.UPDATE...
ISSUED AT 850 PM CDT THU MAR 21 2013
FORECAST APPEARS TO BE ON TRACK...WITH NO CHANGES MADE TO SNOWFALL
AMOUNTS OR ADVISORY AREAS. A BUFFER ZONE OF CHANCE POPS WAS EXPANDED
A COUPLE OF COUNTIES TO THE EAST FOR TONIGHT...MAINLY ALONG A KMDH
TO KPAH TO KHOP LINE. THIS WAS BASED MAINLY ON RUC MODEL DATA. THE
21Z RUC WAS MORE AGGRESSIVE THAN PREVIOUS RUNS IN BRINGING THE DEEP
MOISTURE /AS INDICATED BY 1000 TO 500 MB MEAN RH/ EASTWARD. RADAR
TRENDS SUPPORT THE RUC MODEL. WHATEVER PRECIP MAKES IT INTO THE AREA
OF CHANCE POPS WILL BE INSIGNIFICANT...SINCE THE MODELS DECREASE THE
DEEP MOISTURE FROM NORTHWEST TO SOUTHEAST LATE TONIGHT.
ALSO...SURFACE TEMPS WILL BE AT OR ABOVE FREEZING MUCH OF THE NIGHT
WHERE PRECIP OCCURS.
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 259 PM CDT THU MAR 21 2013
NO CHANGES PLANNED TO THE WINTER WEATHER ADVISORY.
THE 12Z MODELS ARE IN AGREEMENT WITH THE SYNOPTIC-SCALE
FEATURES/EVOLUTION THROUGH FRIDAY NIGHT. THE REGION WILL BE
SANDWICHED UNDER A WEAK UPPER RIDGE THAT SEPARATES A LARGE UPPER
LOW OVER QUEBEC FROM A DIGGING TROUGH OVER THE NORTHERN ROCKIES.
A COUPLE OF RELATIVELY WEAK MID-LEVEL DISTURBANCES WILL TRY TO
PUSH THROUGH THE SKINNY RIDGE AND ACROSS OUR AREA TONIGHT AND
FRIDAY. AS THE WESTERN TROUGH DIGS INTO THE CENTRAL ROCKIES...THE
MID/UPPER RIDGE ASSERTS ITSELF OVER OUR REGION FRIDAY NIGHT.
ALTHOUGH THE NAM AND GFS EACH PRODUCE PLENTY OF CLOUD COVER
TONIGHT AND INTO FRIDAY MORNING OVER THE SOUTHWEST THIRD OF THE
AREA...SIGNIFICANT FOCUSED LIFT IS HARDER TO COME BY. THE TWO
MODELS ARE IN AGREEMENT IN SOME FOCUSED LIFT AROUND 00Z OVER
RIPLEY COUNTY. THE LIFT IS MAXIMIZED IN THE DENDRITIC GROWTH ZONE
WHICH COULD LEAD TO QUITE AN INITIAL BURST OF ACCUMULATING SNOW.
THE PROBLEM IS THAT THE LIFT DOES NOT LAST LONG AT ALL...AND
FOCUSED/SIGNIFICANT LIFT IS HARD TO FIND LATE THIS EVENING AND
OVERNIGHT. WOULD NOT BE BE SURPRISED IF THE ADVISORY IS CANCELLED
EARLY. ON TOP OF THE LIFT ISSUE...THE SNOW WILL HAVE TO OVERCOME
A VERY COLD...DRY AIRMASS FOR LATE MARCH. THIS WILL LIKELY RESULT
IN A VERY SHARP NORTHEAST EDGE TO THE ACCUMULATING SNOW. WILL
LEAVE THE ADVISORY AREA ALONE DUE TO COUNTY GEOMETRY ISSUES...BUT
NORTHEASTERN PORTIONS OF STODDARD AND NEW MADRID AND MAYBE EVEN
WAYNE COUNTY MAY STRUGGLE TO GET AN INCH OF SNOW TONIGHT.
USED HPC QPF AND A 10 TO 1 SNOW TO LIQUID RATIO TO GET VERY SIMILAR
STORM TOTAL SNOW ACCUMULATIONS AS PREVIOUSLY FORECAST. 4 INCHES
WILL BE A REAL POSSIBILITY IN SOUTHWEST PORTIONS OF RIPLEY COUNTY
WITH A SHARP GRADIENT DOWN TO AN INCH FROM GREENVILLE TO DEXTER TO
NEW MADRID.
MODEL SOUNDINGS INDICATE THAT THE COLUMN WILL APPROACH THE
FREEZING LINE IN THE FAR SOUTHWEST LATE THIS EVENING...WHICH WOULD
LEAD TO SOME SLEET POTENTIAL. THIS COULD POTENTIALLY LEAD TO
LOWER ACCUMULATIONS. THE MODELS ARE IN AGREEMENT IN WARMING THE
COLUMN QUICKLY FRIDAY MORNING...SO ANY PRECIPITATION THAT IS LEFT
WILL TRANSITION TO RAIN BY MIDDAY. ANY PRECIPITATION WILL BE FOCUSED
ON THE SOUTHERN BORDER OF THE AREA FRIDAY...BUT WOULD BE SURPRISED
TO SEE MUCH AT ALL. FRIDAY NIGHT SHOULD BE DRY...BUT LEFT A 20-30
POP OVER THE SOUTHERN HALF OF THE AREA JUST TO FIT IN.
IT SHOULD BE QUITE COLD IN THE NORTHEAST TONIGHT...GUIDANCE SEEMS
TO HAVE THIS IN HAND. UNDERCUT GUIDANCE FOR HIGHS FRIDAY IN MOST
LOCATIONS WITH PLENTY OF CLOUDS AND AN EAST WIND EXPECTED. KNOCKED
LOWS FRIDAY NIGHT DOWN QUITE A BIT WITH GOOD RADIATIONAL COOLING
EXPECTED. GUIDANCE HAS A GOOD IDEA FOR FRIDAY NIGHT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 259 PM CDT THU MAR 21 2013
THE GENERAL WEATHER SCENARIO FOR THE WEEKEND AND INTO EARLY NEXT
WEEK HAS STABILIZED SOMEWHAT WITH RESPECT TO THE PROMINENT FEATURES
IMPACTING THE WFO PAH FORECAST AREA.
THE MANDATORY LEVEL TEMPERATURES FROM SURFACE TO 700 MB FOR THE 00Z
AND 12Z THURSDAY NUMERICAL MODEL SUITES INITIALIZED ONE HALF TO
ALMOST TWO DEGREES TOO WARM UPSTREAM AND OVER THE WFO PAH FORECAST
AREA. THE LEAST IMPACTED GUIDANCE HAS BEEN THE DETERMINISTIC NAM-WRF
SUITE...FOLLOWED BY THE SREF/GFS GUIDANCE...THE ECMWF AND CANADIAN
GUIDANCE...FOLLOWED BY THE GFS ENSEMBLE /WHICH IRONICALLY WAS ONE OF
THE BETTER PERFORMING MODELS ON WEDNESDAY/.
WITH RESPECT TO A POP/WEATHER/WEATHER TYPE SOLUTION FOR THE EXTENDED
FORECAST PERIOD...THIS MEANS ESSENTIAL TRACK OF THE NORTH-SOUTH
ORIENTED TROUGH IN THE LEE OF THE CENTRAL ROCKIES WILL DIG INTO A
SURFACE LOW SLIGHTLY FURTHER SOUTH. THE MAIN TRACK OF THE SURFACE
LOW WILL LIKELY BE JUST SOUTH OF THE WFO PAH FORECAST
AREA...POSSIBLY NUDGING INTO SOUTHEAST SECTIONS OF THE PENNYRILE
REGION OF WEST KENTUCKY...NEAR /KHOP/ FORT CAMPBELL KY. BOTH THE
UPPER LOW AND SURFACE LOW WILL MOVE IN CONCERT AND DEEPEN RAPIDLY
/BECOME MORE VERTICALLY STACKED OVER THE SOUTHERN HALF OF THE WFO
PAH FORECAST AREA GENERALLY BETWEEN /10 PM CDT/ SATURDAY NIGHT TO /7
AM CDT/ SUNDAY MORNING.
THE BIG QUESTIONS FOR SATURDAY NIGHT INTO SUNDAY MORNING WILL BE
MULTI-FOLD. THE FIRST QUESTION IS TO WHAT DEGREE OF THE VERTICAL
MOMENTUM /UPWARD MOTION/ WILL BE TRANSLATED INTO HORIZONTAL FORCING
ON THE NORTHERN/SOUTHERN ENDS OF THE WFO PAH FORECAST AREA...MAINLY
IN SURFACE WIND AND TEMPERATURE FIELDS FOR SHARPENING GRADIENTS.
MOST OF THE MODEL GUIDANCE IS SUGGESTING THAT A GOOD PORTION OF THE
ENERGY WILL BE EXPENDED VERTICALLY. THIS NOTION CONTINUES TO SUPPORT
A MENTION OF THUNDERSTORMS ALONG THE SOUTHERN COUNTIES OF THE WFO
PAH FORECAST AREA...WHERE LAPSE RATES/VORTICITY/FORCING WILL SUPPORT
UPRIGHT CONVECTION ALONG AND JUST NORTH OF THE SURFACE LOW. THE
SECOND QUESTION WILL BE WHETHER THE TRANSIENT DEFORMATION ZONE ALONG
ROUTE 60 IN SOUTHEAST MO...ROUTE 13 IN SOUTHERN IL AND THE OHIO
RIVER IN SOUTHWEST IN/NORTHWEST KY...WILL CAUSE A SIGNIFICANT PHASE
CHANGE IN PRECIPITATION TYPE. IT IS CONCEIVABLE THAT THERE MAY BE A
1 TO 3 HOUR PERIOD OVERNIGHT IN THE AFOREMENTIONED AREA WHERE
MID-LEVEL FORCING MAY GENERATE UPRIGHT CONVECTION /THUNDERSTORMS/
AND MIXED PRECIPITATION /SLEET...HAIL...SNOW...RAIN/ NEAR THE
DEFORMATION ZONE. ALSO...GIVEN THE DEMARCATION LINE BETWEEN
MEASURABLE SNOW ALONG THE NORTHERN EDGE OF THE WFO PAH FORECAST
AREA...WOULD PREFER TO SEE THE OUTPUT FROM THE 4KM NAM-WRF GUIDANCE
ON FRIDAY BEFORE PINPOINT PRECIPITATION TYPE...INTENSITY AND THE
OCCURRENCE OF THUNDERSTORMS ALONG THE NORTH END OF THE WFO PAH
FORECAST AREA. THE STORM PREDICTION CENTER HAS ALREADY HINTED IN
THEIR DAY THREE OUTLOOK A CHANCE FOR GENERAL THUNDER ACROSS MOST OF
THE WFO PAH FORECAST AREA. PLAN TO ADD A CONDITIONAL MENTION OF
THUNDER ACROSS THE NORTHERN EDGE OF THE WFO PAH FORECAST AREA FOR
PLANNING PURPOSES...ALTHOUGH THERE WILL BE NO MENTION OF
THUNDERSTORMS IN THE NORTH WITH THIS FORECAST PACKAGE.
FOLLOWING THE PASSAGE OF THE SURFACE/UPPER LOW SATURDAY NIGHT INTO
SUNDAY...THE NUMERICAL MODELS HAVE SPED UP THE DEPARTURE OF
MEASURABLE POPS/WEATHER FROM SOUTHWEST TO NORTHEAST BY AS MUCH AS
SIX HOURS OR MORE. THIS SHOULD DRY THINGS OUT ACROSS THE WFO PAH
FORECAST AREA FROM TUESDAY THROUGH WEDNESDAY. ANOTHER...WEAKER
IMPULSE IS FORECAST TO MOVE THROUGH ON THURSDAY...BUT SHOULD
CONTRIBUTE LITTLE TO ANY MEASURABLE PRECIPITATION.
AS MENTIONED NEAR THE TOP OF THE EXTENDED FORECAST
DISCUSSION...TEMPERATURES WERE TOO WARM. ADJUSTMENTS WERE MADE TO
KEEP TEMPERATURES SOME 15 TO 25 DEGREES BELOW NORMAL AS THE FLOW
AROUND THE SEMI-PERMANENT EASTERN U.S. CYCLONIC VORTEX KEEPS
THICKNESSES LOWER AND SUSTAIN COLD AIR ADVECTION ACROSS THE WFO PAH
FORECAST AREA. WOULD NOT BE SURPRISED TO SEE MULTIPLE DAYS OF COLD
AIR STRATOCUMULUS OR STRATUS...ESPECIALLY ALONG THE NORTHERN 1/2 OF
THE WFO PAH FORECAST AREA. A FEW FLURRIES OR SPRINKLES MAY BE
LIKELY...BUT DO NOT PLAN TO MENTION THESE TRACE EVENTS SO FAR OUT IN
THE FORECAST PACKAGE BASED ON POTENTIAL COVERAGE.
THERE MAY BE SOME LIGHT AT THE END OF THE COLD TEMPERATURE
TUNNEL...AS THE 240 HOUR GUIDANCE SHOWS A STRONG RIDGE NOSING INTO
WESTERN MO...IT MAY TAKE UNTIL THE FIRST WEEK OF APRIL BEFORE WE SEE
ANY MEASURABLE WARMING AT OR ABOVE NORMAL /LOW TO MID 60S/ THIS TIME
OF YEAR.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1214 PM CDT THU MAR 21 2013
THE WINTER STORM SYSTEM TONIGHT IS NOT EXPECTED TO IMPACT ANY OF
THE TERMINALS. SOME LOW VFR STRATO CU CEILINGS WILL CONTINUE FOR
MUCH OF THE AFTERNOON IN THE NORTHEAST...ESPECIALLY AT KOWB. SURFACE
HIGH PRESSURE OVER THE REGION WILL KEEP WINDS LIGHT THROUGH THE
PERIOD. THE LONE EXCEPTION WILL BE AT KOWB EARLY THIS AFTERNOON
WHEN A FEW GUSTS INTO THE TEENS WILL BE POSSIBLE.
MID AND HIGH CLOUDS WILL OVERSPREAD KCGI AND KPAH QUICKLY THIS
AFTERNOON...AND THEN WILL GRADUALLY LOWER THROUGH THE PERIOD. SOME
GUIDANCE IS HINTING AT MVFR CEILINGS AT BOTH SITES 09Z-15Z
FRIDAY...BUT CONFIDENCE IS TOO LOW TO MENTION AT THIS TIME. AS FOR
PRECIPITATION...CANNOT RULE OUT A FEW FLURRIES THROUGH THE NIGHT
AND INTO FRIDAY MORNING...BUT FORCING FOR ANY SIGNIFICANT
PRECIPITATION IS HARD TO FIND. KEPT KCGI AND KPAH DRY AND VFR
THROUGHOUT THE 18Z TAF PERIOD.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...WINTER WEATHER ADVISORY UNTIL 7 AM CDT FRIDAY FOR
MOZ100-107>110-114.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...MY
SHORT TERM...DRS
LONG TERM...SMITH
AVIATION...DRS
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
950 PM CDT THU MAR 21 2013
.DISCUSSION...
WARM 60S OVER DEEP E TX AND LOW TO MID 40S ACROSS OUR NORTHERN
COUNTIES WITH 50S IN A THIN BELT BETWEEN. THE FRONT LIES ACROSS NE
TX AND TOLEDO BEND COUNTRY RUNNING EAST UNDER I-20. UNDER CUTTING
IS GUIDANCE IS ONE THING BUT GETTING DOWN A FEW DEGREES BELOW
CURRENT OBSERVATION WAS MORE THE PROCESS WITH THIS UPDATE. THE
EASTERLY FLOW NORTH OF I-20 REMAINS CHILLED WITH 10 PLUS DEGREES
SPREADS FOR MORE EVAPORATIVE COOLING AS WELL. HOPE A FEW DEGREES
WORKS OUT. LITTLE CHANGE NEEDED ELSEWHERE WITH STILL SOUTHERLY
GUSTS OVER OUR SOUTHERN TIERS AND THAT ENERGY IS RIDING OVER THE
FRONTAL BOUNDARY. MOST OF THE RAIN SHIELD OVER ARKANSAS CONTINUES
TO LIFT AWAY WITH SOME NEW DEVELOPMENT ALONG THE RED IN THE I-30
CORRIDOR. THIS TREND IS MODELED TO CONTINUE AMONGST MANY FROM THE
NAM TO RAP TO GFS AND EURO. AND WE CERTAINLY DO NEED THE RAIN JUST
ABOUT AREA WIDE WHILE THE GETTING IS GOOD...BUT THE NORTHERN HALF
WILL FAIR WELL WITH HIGH POPS ALREADY OUT. /24/
&&
.AVIATION...
VFR FLIGHT CONDITIONS TO DETERIORATE TO MVFR/IFR OVERNIGHT AS LOW
LEVEL MOISTURE INCREASES. ALONG WITH RESTRICTED VISIBILITIES...
SHOWERS AND ISOLATED THUNDERSTORMS TO INCREASE IN COVERAGE. LITTLE
IMPROVEMENT EXPECTED ON FRIDAY. SURFACE WIND EAST TO SOUTHEAST
AROUND 5 KNOTS OVERNIGHT TO BECOME SOUTH 5 TO 10 KNOTS AFTER
DAYBREAK THEN SHIFT TO THE NORTHWEST AFTER 18Z. /05/
&&
.PREV DISCUSSION... /ISSUED 703 PM CDT THU MAR 21 2013/
DISCUSSION...
JUST AN UPDATE TO THE ZONE FORECAST AND THE REC TO REMOVE THE LAKE
WIND ADVISORY HEADLINES FROM TONIGHT. /24/
PREV DISCUSSION... /ISSUED 338 PM CDT THU MAR 21 2013/
DISCUSSION...
A COMPLEX FCST CONTINUES TO UNFOLD IN THE NEAR TERM. A SHEAR
AXIS/WARM FRONT IS NOTED FROM NEAR CLARKSVILLE TX...TO MINDEN
LA...TO MONROE...SEPARATING A 10-15 DEGREE TEMP DIFFERENCE EITHER
SIDE. THIS BOUNDARY HAS SERVED AS A FOCUS FOR SHOWERS TODAY AS IT
HAS DRIFTED NEWD. SFC ANALYSIS SHOWS A LOW PRESSURE CENTER
CURRENTLY OVER THE TX PANHANDLE...WHICH HAS TIGHTENED THE PRESSURE
GRADIENT SUCH THAT GUSTY WINDS HAVE BEEN OBSERVED ACROSS MUCH OF
TX. THE REGION IS UNDER DISTURBED WNW FLOW ALOFT...PER THE WV
IMAGERY...WHICH IS PROVIDING JUST ENOUGH LIFT TO GENERATE SHOWERS
AND ISOLD THUNDERSTORMS ACROSS MUCH OF ERN OK/WRN AR.
THE SFC LOW IS FCST TO PUSH ESEWD TONIGHT THROUGH FRIDAY...BEFORE
FILLING AND STALLING /ALONG WITH THE ASSOCIATED FRONTAL BOUNDARY/ OVER
DEEP E TX...ALL THE WHILE KEEPING WIDESPREAD ELEVATED CONVECTION
GOING MAINLY ALONG AND N OF I-20. THIS WOULD LEAVE PARTS OF THE
REGION ALONG AND S OF I-20 IN THE WARM SECTOR FOR FRIDAY. WITH
AMPLE VERTICAL WIND SHEAR AND MODERATE INSTABILITY IN PLACE...AT
LEAST AN ISOLATED SEVERE THREAT APPEARS POSSIBLE. HOWEVER...THIS
AREA IS FCST TO HAVE A SIGNIFICANT CAP IN PLACE...AND MODELS ARE
NOT GENERATING MUCH IF ANY QPF. SO...THERE IS MUCH UNCERTAINTY TO
SAY THE LEAST.
AS WE MOVE INTO FRIDAY NIGHT/SATURDAY MORNING...ANOTHER SFC LOW IS
FCST TO DEVELOP IN THE SRN PLAINS...AS THE MAIN UPPER DISTURBANCE
MOVES ACROSS THE ROCKIES. THE UPPER TROF WILL PUSH THE SFC LOW EWD
ALONG THE RED RIVER THROUGH SATURDAY...AS ANOTHER WAVE OF
CONVECTION RAMPS UP ACROSS OUR REGION. THIS WILL LIKELY BRING A
THREAT FOR SEVERE WEATHER PARTICULARLY IN THE WARM SECTOR S OF THE
STALLED FRONTAL BOUNDARY. THE POSITION OF THE BOUNDARY IS STILL
SOMEWHAT UNCERTAIN ATTM...BUT IS EXPECTED TO BE SOMEWHERE IN THE
VICINITY OF I-20. UPPER LEVEL SUPPORT FOR THIS WAVE WILL BE QUITE
A BIT STRONGER THAN ANY DISTURBANCES FRIDAY...AND THUS WILL CARRY
A BETTER POTENTIAL TO PRODUCE STORMS CAPABLE OF DAMAGING WINDS AND
HAIL.
AS THE UPPER LOW PUSHES EWD SUNDAY...RAIN WILL COME TO AN END FROM
W TO E SUNDAY MORNING THROUGH SUNDAY AFTERNOON...LEAVING THE
REGION UNDER NEAR-ZONAL FLOW ALOFT. ANOTHER UPPER TROF IS FCST TO
DIG SEWD ACROSS THE SRN PLAINS TUESDAY...BRINGING A DRY BACK-DOOR
FRONT INTO THE REGION...WITH HIGH PRESSURE AT THE SFC TO BUILD IN AND
NW FLOW ALOFT IN ITS WAKE. /12/
AVIATION...
VFR FLIGHT CATEGORIES WILL CONTINUE THROUGH THE REMAINDER OF THE
DAYLIGHT HOURS TODAY WITH OCCASIONAL CIGS BETWEEN 5 AND 9 KFT. AS
LOW LEVEL MOISTURE INCREASES...EXPECT CIGS AND VISIBILITY TO
GRADUALLY BECOME MVFR TONIGHT...ESPECIALLY IN AND AROUND SCATTERED
TO NUMEROUS SHOWERS AND ISOLATED TSTMS. ALSO EXPECT PERIODS OF IFR
CIGS AND VISIBILITY AS THE LOWER LEVELS BECOME SATURATED. ONLY
SLOW IMPROVEMENT EXPECTED ON FRIDAY...WITH SOME IMPROVEMENT FROM
WEST TO EAST AFTER 18Z. FREEZING LEVELS WILL RANGE FROM 6 KFT
NORTH TO 11 KFT SOUTH...WITH ICING POSSIBLE ABOVE THESE LEVELS.
MODERATE TURBULENCE EXPECTED VICINITY TSTMS. SURFACE WIND EAST TO
SOUTHEAST... MOSTLY IN THE 10 TO 15 KT RANGE...WITH HIGHER GUSTS.
/14/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 50 70 51 65 47 / 50 30 30 60 20
MLU 48 65 51 67 50 / 50 50 30 60 40
DEQ 39 55 42 56 40 / 70 40 30 60 30
TXK 42 59 45 59 42 / 70 50 30 60 30
ELD 41 58 45 61 43 / 70 50 30 60 40
TYR 60 73 51 65 43 / 30 30 30 50 20
GGG 54 71 52 65 46 / 40 30 30 50 20
LFK 59 79 59 73 46 / 20 30 30 50 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
24/05
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
934 PM EDT THU MAR 21 2013
.SYNOPSIS...
LOW PRESSURE SLOWLY LIFTS NORTH INTO PENNSYLVANIA AS SURFACE HIGH
PRESSURE BUILDS INTO THE MID-ATLANTIC THROUGH SATURDAY. STRONGER LOW
PRESSURE WILL PUSH FROM THE OHIO VALLEY INTO THE AREA SUNDAY AND
MONDAY. LOW PRESSURE WILL REMAIN IN PLACE THROUGH EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
UPPER LOW OVER ERN CANADA REMAINS CUTOFF DUE TO AMPLIFIED
DOWNSTREAM BLOCK PRESENT OVER THE NRN ATLANTIC AND A WEAK POLAR
VORTEX. A NW TRAJECTORY AROUND THE LOW WILL CONTINUE TO KEEP THE
MID-ATLANTIC REGION IN AN WINTER-LIKE PATTERN. WHENEVER HIGHS
DURING THE DAY ARE ONLY NEAR NORMAL MIN TEMPS VALUES...THERE IS A
GOOD BET FOR UNSEASONABLY COLD TEMPS AT NGT. WHILE WINDS WILL KEEP
TEMPS FROM BOTTOMING OUT TNGT...MIN TEMPS IN THE 20S ARE EXPECTED
CWA-WIDE /WHICH ARE ABOUT 10F BELOW NORMAL/.
LAST FEW RUNS OF THE RAP APPEAR TO HAVE A GOOD HANDLE ON A SHORTWAVE
TROUGH APPROACHING THE NRN MID-ATLANTIC STATES LATE THIS EVE AND
ANOTHER LATE TNGT. ENHANCED LIFT AHEAD OF THESE DISTURBANCES MAY
PRODUCE INTERMITTENT SNOW SHOWERS AND FLURRIES ALONG THE WRN
SLOPES OF THE ALLEGHENY FRONT. SNOW ACCUMULATIONS SHOULD BE UNDER
AN INCH TNGT.
WINDS 10-20 MPH IN THE WESTERN MOUNTAINS WILL COMBINE WITH
TEMPERATURES IN THE 20/S TO CREATE WIND CHILLS NEAR ZERO...QUITE
FRIGID FOR THIS TIME OF YEAR.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
SURFACE HIGH PRESSURE PUSHES IN BEHIND THE NEXT WAVE TOMORROW.
TOMORROW MAY BE A LOT LIKE TODAY WITH SLIGHTLY WARMER...THOUGH
CONTINUED BELOW NORMAL TEMPERATURES IN THE 40S IN THE METRO AREAS.
ANY SNOW FLURRIES / SHOWERS WILL END IN THE WESTERN MOUNTAINS BY
EARLY AFTERNOON. COLD TEMPERATURES AND GUSTY WINDS WILL CONTINUE.
AFTER ONE UPPER LOW FINALLY MOVES OFF THE NEW ENGLAND COAST THIS
WEEKEND...ANOTHER WILL QUICKLY TAKE ITS PLACE - KEEPING THE REGION
IN A CONTINUED COOL LATE SEASON PATTERN. THE TRANSITION PERIOD
BETWEEN THESE TWO SYSTEMS WILL FEATURE ANOTHER MIX OF WINTRY PRECIP
OVER THE AREA. SATURDAY WILL BE ANOTHER REPRIEVE FROM THE COOL/DRY
AND BREEZY WX FROM THE LATER HALF OF THE CURRENT WEEK - BUT STILL
BELOW AVG TEMPS. SKIES WILL LARGELY CLEAR OUT AND WINDS WILL DROP
OFF TO A STIFF BREEZE ON SAT AFTN...W/ HIGHS BARELY REACHING 50
ACROSS THE SRN HALF OF THE AREA AND AT LEAST U40S OVER THE NRN
HALF.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
FROM MIDDAY SUNDAY THRU LATE MON...WILL BE THE HIGHLIGHTED TIME FOR
THE CWA TO RECEIVE PRECIP. THE SYSTEM WILL AGAIN BE ANOTHER COMPLEX
DOUBLE SFC LOW SYSTEM...W/ THE SRN LOW PASSING WELL TO OUR SOUTH AND
THE LOW MAINLY AFFECTING OUR AREA BEING THE OHIO VLY LOW. THE SYSTEM
AS A WHOLE WILL BE BLOCKED TO THE NORTH BY AN UPPER VORT STATIONED
OVER THE ST. LAWRENCE VLY...PREVENTING THE LOWS FROM RETREATING
NEWD...SLOWING DOWN AND BECOMING MUCH MORE INFLUENCED BY THE WARMER
COASTAL WATERS. INSTEAD...THIS WAVE OF PRECIP WILL BE MORE
PROGRESSIVE MOVING WEST -> EAST AT A STEADIER PACE.
THE IMPORTANT FACTOR FOR WINTRY PRECIP HOWEVER LIES IN THE SPATIAL
DISTANCE BETWEEN THE TWO LOWS. THE FIRST LOW WILL MOVE OFF THE SRN
ATLC COAST SUN AFTN...CARRYING A LARGE AREA OF PRECIP ACROSS THE
CAROLINAS AND INTO THE MID ATLC. BY THE TIME OF BULK OF THE PRECIP
SLIDES NWD INTO OUR AREA...TEMPS WILL BE WELL ABOVE FREEZING OUTSIDE
OF THE HIGHER TERRAIN. NOW INTO LATE MARCH...THESE SYSTEMS THAT
CONTAIN SNOW AS THEY DROP INTO LOWER LATITUDES WILL BE BATTLING THE
NEAR-SFC CONDITIONS FOR ACCUMULATING SNOWS - OR EVEN STAYING SNOW
WITHIN THE LOWEST FEW HUNDRED FT APPROACHING THE LOWLANDS/COASTAL
AREAS.
THE WRN HALF OF THE CWA WILL SEE THE BEST POTENTIAL FOR ACCUMULATING
SNOW SUN NIGHT INTO EARLY MON...A MIX FROM THE SHEN VLY TO THE I-95
CORRIDOR AND MAINLY RAIN ALONG THE WRN/SRN SHORE COUNTIES OF MD
ALONG THE BAY. TOTAL QPF FROM THIS SYSTEM RANGE FROM QUARTER-HALF
INCH RANGE FOR MOST MED RANGE GUIDANCE...NOTHING SUBSTANTIALLY
HIGHER OUTSIDE THE MTNS W/ ONLY SLIGHTLY HIGHER VALUES THEMSELVES.
AS THIS SECONDARY LOW SHIFTS OFF THE COAST EARLY MONDAY...PLENTY NW
FLOW STRAITED PRECIP BANDS WILL MOVE ACROSS THE AREA. THOUGH SFC
TEMPS WILL LIKELY BE ABOVE FREEZING THROUGHOUT THE DAY...FALLING
PRECIP WILL BE ALL SNOW FOR MUCH OF THE AREA - OUTSIDE THE BAY.
ACCUMULATIONS WILL BE MINIMAL...IF ANY...FROM THE SHORT DURATION AND
LOW EXPECTED QPF. GUSTY WINDS WILL CARRY THIS ACTIVITY OFF THE COAST
INTO TUE...THEN DAILY PASSAGE OF WEAKER UPPER WAVES THAT WILL
BASICALLY REINFORCE THE SAME TYPE OF WEATHER EACH DAY INTO THE
COMING WEEK - HIGHS U40S/LOWS NEAR FREEZING - CLEAR AT NIGHT - MOSTLY
CLOUDY DURING THE AFTN.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS TNGT AND FRI. WITH THE LOSS OF DAYTIME HEATING...
HIGH BASED STRATOCU FIELD HAS JUST ABOUT DIMINISHED WHILE GUSTY NW
WINDS HAVE SUBSIDED A BIT. STILL EXPECT NW WINDS 5-10 KT OVNGT
WITH AN OCCASIONAL HIGHER GUST POSSIBLE.
BREEZY NW WINDS CONTINUE FRI...ESPECIALLY DURING THE MRNG WHEN
GUSTS 20-25 KT EXPECTED. NW SFC WINDS DECREASE BY AFTERNOON TO
5-15 KTS.
QUIET SAT W/ SOLID VFR CONDS UNTIL MID MRNG SUN...WHEN CLOUDS
INCREASE AND PRECIP ARRIVES FROM THE SW. THIS WILL MAINLY BE RAIN
ACROSS THE REGION INTO SUN NIGHT...WHEN A PERIOD OF SNOW/RAIN MIX
WILL BE POSSIBLE FROM THE SHEN VLY TO THE I-95 CORRIDOR. ANY SNOW
ACCUM OUTSIDE THE MTNS SHOULD BE LIGHT...AND ALSO FALLING INTO AN
ENVIRONMENT AT LEAST A COUPLE OF DEG ABOVE FREEZING. SOME LEFTOVER
SNOW BANDS ON MON...BUT GUSTY WINDS AND HIGH-END MVFR CIGS THE
MAIN CONCERN. THESE CLOUD DECKS AND BREEZY NW WINDS WILL RETURN
NEARLY EACH DAY/AFTN FOR THE REMAINDER OF THE WEEK.
&&
.MARINE...
NWLY WINDS HAVE SUBSIDED A BIT AFTER SUNSET...BUT STILL REMAIN IN
THE 15 TO 25 KT RANGE. SCA REMAINS IN EFFECT OVNGT ALTHOUGH A
BRIEF LULL IN THE WINDS ARE POSSIBLE. GUSTY WINDS ARE EXPECTED
AGAIN ON FRIDAY...AND SCA REMAINS IN PLACE.
SCA CONDITIONS NEARLY EACH DAY FROM THE WEEKEND INTO THE MIDDLE OF
NEXT WEEK...AND LIKELY BEYOND. EACH OF THESE WILL BE OF THE
LOWER-END VARIETY BUT STILL BREEZY EACH AFTN AT LEAST. A LOW
PRESSURE SYSTEM WILL SLIDE ACROSS THE REGION FROM LATE SUN THRU
LATE MON. SOME BREEZY CONDITIONS AND MAINLY RAIN FOR THE COASTAL
AREAS. DRY THRU REST OF THE WEEK...OUTSIDE OF A BRIEF SHOWER OR
TWO BUT WINDS WILL DROP OFF AT NIGHT AND PICK UP BY THE NEXT AFTN.
&&
.FIRE WEATHER...
HUMIDITY WILL ONLY RECOVER TO 50-60% TONIGHT...AND WITH HIGH
PRESSURE BUILDING IN AND A SHORT WAVE MOVING BY TOMORROW...LOCALLY
ENHANCED THREATS OF WILDFIRE SPREAD ARE POSSIBLE FRIDAY. WINDS DO
NOT APPEAR TO BE AS STRONG YESTERDAY AFTERNOON...COORDINATION WITH
AREA FIRE MANAGERS EARLIER TODAY SUPPORTS THIS THREAT IS TOO
LOCALIZED FOR THE ISSUANCE OF ANY STATEMENTS AT THIS TIME.
SAT...MAINLY CLEAR SKIES AND RELATIVELY WARMER TEMPS - IN THE
L50S. WINDS WILL BE LIGHTER THOUGH...AND EVEN W/ RH VALUES IN THE
L30S THE HIGHER WIND GUSTS WILL BE ACROSS NRN MD WHERE THE HIGHER
RH VALUES WILL BE LOCATED.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT FRIDAY FOR ANZ530>543.
&&
$$
UPDATE...KLEIN
PREV DISC...SDG/GMS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
146 AM EDT WED MAR 20 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 415 PM EDT TUE MAR 19 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP CLOSED LO
CENTERED OVER ERN LK SUP DOWNSTREAM OF RDG ALONG THE W COAST. DEEP
CYC NW FLOW OF COLD AIR ARND THE SFC LO NEAR WAWA ONTARIO IS
DOMINATING THE CWA...CAUSING LES OVER MAINLY THE WRN ZNS EARLY THIS
AFTN AS -16C H85 TEMPS SHOWN AT INL AT 12Z MOVE OVER THE LAKE. WITH
SHARPENING PRES GRADIENT BTWN PRES RISE CENTER OVER NRN MN AND PRES
FALLS OVER SE ONTARIO TO THE E OF THE SFC LO...THE NW WINDS ARE
STRENGTHENING...WITH WIND GUSTS UP TO 40 MPH REPORTED CAUSING
EXTENSIVE BLSN. THE SN HAS TAPERED OFF OVER THE FAR W AND SCENTRAL
WITH THE ADVECTION OF DRIER AIR OBSVD IN MN AT 12Z/WELL DEPICTED ON
THE 12Z MPX RAOB AND DOWNSLOPE FLOW INTO THE SCENTRAL. PUBLIC
REPORTS INDICATE AS MUCH AS 18 INCHES OF SN HAS FALLEN OVER THE HIER
TERRAIN OF THE W. FARTHER UPSTREAM...ANOTHER SHRTWV IS DIGGING SEWD
THRU LK WINNIPEG.
MAIN FCST CONCERNS THRU WED REMAIN LES/WIND TRENDS AND GOING
HEADLINES AS CLOSED LO DRIFTS ONLY SLOWLY TO THE ENE THRU SE CANADA.
LATE TODAY/TNGT...OVERALL DEEP CYC NW FLOW ARND SLOWLY DEPARTING LO
IS PROGGED TO LINGER AND CAUSE PERSISTENT LES IN THE NW WIND SN
BELTS. THE LES INTENSITY OVER THE FAR W...ESPECIALLY WHERE THE FETCH
ACRS THE OPEN WATER IS SHORTER NEAR IWD...HAS DIMINISHED AS DRIER
AIR IN MN SLID EWD. THIS DRY AIR WL IMPACT MAINLY THE AREAS NEAR THE
WI BORDER. SO THE SCENTRAL SHOULD REMAIN DRY WITH DOWNSLOPING DRIER
FLOW. BUT LATER TNGT...SHRTWV NOW NEAR LK WINNIPEG IS FCST TO DIG
SEWD...CAUSING THE LLVL FLOW TO VEER A BIT AND BRING BACK A RETURN
OF DEEPER MSTR OVER THE ENTIRE CWA ON THE CYC SIDE OF ITS TRACK.
THESE TRENDS SHOULD CAUSE LES TO PICK UP AGAIN AT IWD FOLLOWING A
BREAK THIS EVNG. IN THE NW WIND SN BELTS E OF MQT...THE ARRIVAL OF
COLDER AIR WL LIKELY ENHANCE THE INTENSITY OF THE LES THRU THE NGT
WITH FVRBL WNW LLVL FLOW SHIFTING NW. ANOTHER FACTOR FAVORING HEAVY
SN IS FVRBL ALIGNMENT OF FCST UVV MAX WITHIN THE DGZ EVEN IF STRONG
WINDS THAT CAUSE A BREAK UP OF THE DENDRITES ACT TO REDUCE THE
SN/WATER RATIOS A BIT. BUT THESE STRONG WINDS WL CAUSE EXTENSIVE
BLSN/REDUCED VSBY ESPECIALLY NEAR LK SUP...EVEN WHEN THE LES IS NOT
FALLING HEAVILY.
WED...AS THE CLOSED LO SLOWLY DRIFTS TO THE E...CYC NW FLOW IS
PROGGED TO VEER SLOWLY TO THE NNW. WITH THE ARRIVAL OF SOMEWHAT
WARMER ATLANTIC AIR FM THE NE ARND INTENSE LO PER THE 12Z GFS AND
ESPECIALLY THE NAM...DEEP MSTR IS FCST TO LINGER. ALTHOUGH THE
WARMING WITH H85 TEMPS PROGGED TO RISE TOWARD -10C OVER FAR ERN LK
SUP MIGHT TEND TO REDUCE LES INTENSITY...THE ARRIVAL OF SOME LARGER
SCALE QVECTOR CNVGC/MAINTENANCE OF DEEPER MSTR ASSOCIATED SOME
ISENTROPIC ASCENT WL RETAIN A LK ENHANCED COMPONENT. ALTHOUGH THE
BEST CHC FOR CONTINUED DRY WX WL BE OVER THE SCENTRL...FCST SDNGS
INDICATE THE MSTR WL BE DEEP ENUF TO SUPPORT AT LEAST SCT -SHSN.
SOME OF THE GUIDANCE SUGGESTS SOME DRIER AIR MAY ARRIVE OVER THE W
ON WED AFTN... BUT SLOW MOTION OF THE CLOSED LO TO THE E FAVORS THE
MODELS THAT SHOW A SLOWER EWD PROGRESSION OF THIS DRYING.
GOING HEADLINES LOOK TO BE IN GOOD SHAPE AS LONG DURATION EVENT WL
ADD TO SN ACCUMS THAT HAVE ALREADY HIT WARNING TOTALS IN MOST AREAS
WHERE THESE HEADLINES HAVE BEEN IN EFFECT. EXPECT STORM TOTAL SN TO
REACH 24 INCHES OR MORE OVER THE HIER TERRAIN OF THE W.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 415 PM EDT TUE MAR 19 2013
LOOK FOR A SLOW AND STEADY RISE IN TEMPERATURES THROUGH THE PERIOD
AS WE SLOWLY LOSE THE INFLUENCE OF THE NEARBY 500MB TROUGH.
THE ELONGATED 500MB TROUGH WILL EXTEND FROM JUST NE OF MAINE TO
LOWER MI...AND SOUTHERN UPPER PORTIONS OF UPPER MI AT 00Z
THURSDAY...WITH A SIZABLE RIDGE STRETCHING ACROSS WYOMING AND THE
WESTERN DAKOTAS UP THROUGH SASKATCHEWAN.
WHILE THE 500MB RIDGE WILL PUSH INTO WESTERN UPPER MI/LAKE SUPERIOR
FRIDAY...IT WILL TAKE UNTIL FRIDAY NIGHT UNTIL THE NEARLY STEADY
STATE LOW OVER THE EAST PUSHES OFFSHORE. THE 19/00Z RUNS OF THE
ECMWF AND CANADIAN HOLD ONTO THE TROUGH ACROSS EASTERN UPPER MI A
BIT LONGER THAN THE GFS /BY ROUGHLY 6HRS/. THE SFC TROUGH WILL
LIKELY LINGER ACROSS EASTERN MICHIGAN THROUGH 12Z FRIDAY. THE RESULT
WILL BE CONTINUED LAKE EFFECT SNOW SHOWERS FOR NORTHERLY-NNW WIND
FAVORED LOCATIONS NEAR LAKE SUPERIOR. 850MB TEMPS WILL MODERATE FROM
THE -12 TO -15C AT 00Z THURSDAY TO AROUND -8C BY DAYBREAK FRIDAY.
EXPECT QUICKLY DIMINISHING LAKE EFFECT SNOW SHOWERS AFTER THURSDAY
AFTERNOON...WITH LOWERING INVERSION HEIGHTS
500MB RIDGING WILL BE THE RULE FRIDAY NIGHT THROUGH AT LEAST
SATURDAY NIGHT.
LOOK FOR A CLUSTERED AREA OF LOW PRESSURE CENTERED NEAR MONTANA AT
00Z SATURDAY WILL DIVIDE FRIDAY NIGHT...WITH THE NORTHERN LOW
SPINNING IN PLACE...AND THE SOUTHERN EXTENT OF THE TROUGH DIVING
ACROSS TEXAS AND OKLAHOMA BY LATE SATURDAY AFTERNOON/SATURDAY NIGHT.
THE 00Z RUNS OF THE GFS AND ECMWF WERE FAIRLY CONSISTENT WITH THE
TRACK OF THE SOUTHERN TROUGH...MOVING IT OVER KENTUCKY AND WEST
VIRGINIA BY DAYBREAK MONDAY...WITH THE RIDGE WEAKENING BUT STILL
REMAINING OVER LAKE SUPERIOR AND UPPER MICHIGAN THROUGH AT LEAST
SUNDAY NIGHT. THE 12Z GFS CAME IN WITH THE 500MB LOW SHIFTED APPROX
250MI TO THE NORTHWEST OF THE 00Z RUN TRACK...WHICH WOULD BRING IT
ACROSS LOWER MI AT 00Z TUESDAY. THIS WOULD RESULT IN STRONGER WINDS
FOR CENTRAL AND EASTERN AREAS...AS WELL AS UPSLOPE LES NORTH CENTRAL
WITH SYNOPTIC SNOW HUGGING THE EASTERN COUNTIES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 140 AM EDT WED MAR 20 2013
WITH A COLD CYCLONIC NW FLOW CONTINUING AROUND LOW PRES DEPARTING
SLOWLY THROUGH NORTHERN ONTARIO THIS FCST PERIOD...EXPECT SHSN TO
IMPACT CMX/IWD...WITH IFR/LIFR CONDITIONS PREDOMINATING. THE WORST
CONDITIONS TO VLIFR ARE MOST LIKELY AT THE MORE EXPOSED CMX LOCATION
WITH DEEPER MOISTURE AND STRONGER WINDS. AT SAW...DOWNSLOPING NW
WINDS SHOULD RESULT IN MAINLY MVFR CONDITIONS THRU THE FCST PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 415 PM EDT TUE MAR 19 2013
EXPECT NW GALES/HEAVY FREEZING SPRAY TO LINGER THRU AT LEAST WED
MORNING AS DEEP LO PRES OVER SE ONTARIO EDGES SLOWLY TO THE E AND A
COLD...GUSTY NW WIND CONTINUES. WINDS/FREEZING SPRAY ARE LIKELY TO
DIMINISH OVER THE W WED AFTERNOON FARTHER FROM THE SLOWLY RETREATING
LO.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING UNTIL 8 PM EDT /7 PM CDT/ THIS EVENING FOR
MIZ001>004-009-084.
WINTER STORM WARNING UNTIL 8 AM EDT THURSDAY FOR MIZ006-007-085.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 8 PM EDT /7 PM CDT/ THIS
EVENING FOR LSZ162-240>245-248>251-263>267.
GALE WARNING UNTIL 2 PM EDT /1 PM CDT/ THIS AFTERNOON FOR LSZ162-
243>245-249>251-263>267.
GALE WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR LSZ248.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KF
AVIATION...JLB
MARINE...KC
AREA FORECAST DISCUSSION
NWS DULUTH MN
732 PM CDT THU MAR 21 2013
.AVIATION.../00Z TAF ISSUANCE/
VFR CONDITIONS WILL BE FOUND ACROSS THE REGION DURING THE
EVENING...ALTHOUGH SOME IFR/LIFR CIGS/VSBYS WILL BE POSSIBLE IN
SPOTS AS THE NIGHT WEARS ON DUE TO SOME FOG. CONDITIONS WILL
IMPROVE TO VFR AGAIN ON FRIDAY.
&&
.PREV DISCUSSION... /ISSUED 308 PM CDT THU MAR 21 2013/
SHORT TERM.../NOW - FRIDAY/
AT 3PM/2000Z...THERE WAS A RIDGE OF HIGH PRESSURE OVER THE
NORTHERN PLAINS AND SOUTHERN MINNESOTA. THE NORTHLAND HAD LIGHT NW
WINDS DUE TO A LARGE LOW PRESSURE SYSTEM OVER THE NORTHEASTERN
UNITED STATES AND SOUTHEASTERN CANADA. MOST OF THE NORTHLAND HAD
SUNNY TO MOSTLY SUNNY SKIES...BUT THERE WAS STILL SOME LINGERING
LAKE EFFECT SNOW RELATED OVC CLOUDS OVER THE FAR EASTERN FORECAST
AREA IN NW WISCONSIN. THE OVC CLOUDS WERE QUICKLY DIMINISHING AS
THE WINDS WEAKENED OVER WESTERN LAKE SUPERIOR...CUTTING OFF THE
MOISTURE SUPPLY. TEMPERATURES WERE IN THE LOWER TO UPPER 20S
ACROSS THE NORTHLAND.
TONIGHT...THE HIGH PRESSURE IN THE NORTHERN PLAINS WILL SLOWLY
MOVE INTO THE NORTHLAND. THE NORTHLAND CAN EXPECT CLEAR TO MOSTLY
CLEAR SKIES. THERE COULD BE SOME CLOUDS OVER THE TIP OF THE
ARROWHEAD LATE TONIGHT. THE NAM AND RAP INDICATE SOME ENHANCED LOW
LEVEL MOISTURE MOVING INTO THAT AREA...BUT LEANED ON A CLEAR
FORECAST. THE MODEL GUIDANCE IS LIKELY MUCH TOO WARM CONSIDERING
THE CLEAR SKIES AND VERY LIGHT WINDS EXPECTED FOR TONIGHT...SO
UNDERCUT THE MODEL CONSENSUS BY SEVERAL DEGREES. OVERNIGHT LOWS
WILL PROBABLY BE WELL INTO THE SINGLE DIGITS BELOW ZERO ACROSS
MOST OF THE NORTHLAND.
FRIDAY...THE HIGH PRESSURE OVER THE NORTHLAND WILL PROMOTE SUNNY
TO MOSTLY SUNNY SKIES FOR AT LEAST THE MORNING. THERE COULD BE
SOME INCREASING CLOUD COVER IN THE AFTERNOON BASED ON MODEL RH.
HOWEVER...LEANED ON LESS CLOUD COVER SINCE THE MODELS SEEM TO BE
EXAGGERATING THE POTENTIAL FOR CLOUD COVER. FRIDAY COULD VERY
EASILY BE SUNNY ACROSS THE REGION...SO UPDATES MIGHT NEED TO BE
MADE IN THE FUTURE. HIGH TEMPERATURES WILL LIKELY BE IN THE LOWER
30S.
LONG TERM.../FRIDAY NIGHT - WEDNESDAY NIGHT/
CONTINUED QUIET WEATHER CONDITIONS THROUGH THE WEEKEND AND INTO
THE MIDDLE OF NEXT WEEK WITH A NARROW RIDGE OF HIGH PRESSURE
SITUATED OVER THE UPPER MIDWEST BETWEEN TWO SLOW MOVING UPPER
LOWS. THE LOW TO THE WEST WILL EVENTUALLY UNDERCUT THE HIGH
PRESSURE BY THIS WEEKEND. HOWEVER...THE ACTIVE PATTERN WILL REMAIN
WELL TO THE SOUTH AND LEAVE THE NORTHLAND MOSTLY DEVOID OF
PRECIPITATION. THE LOW LEVEL FLOW WILL BE FAVORABLE FOR A
PERSISTENT E/NE WIND OFF LAKE SUPERIOR AND KEEP MUCH OF THE
NORTHLAND UNDER THE INFLUENCE OF MOSTLY CLOUDY SKIES THROUGH THE
WEEK. THE LACK OF SUN...COMBINED WITH A RELATIVELY COLD AIR
MASS...850MB TEMPS -11 DEG C...WILL KEEP AFTERNOON HIGHS IN THE
LOWER 30S AND OVERNIGHT LOWS IN THE TEENS. ROUGHLY 5-10 DEG BELOW
AVERAGE. COULD SEE A FEW WEAK WAVES ROTATE WWD FROM THE UPPER
TROUGH OVER ERN CANADA EARLY NEXT WEEK...BUT ONLY A SLIGHT CHANCE
OF LIGHT SNOW IS POSSIBLE FROM THESE...WITH LITTLE TO NO SNOW
ACCUMULATING.
AVIATION.../18Z TAF ISSUANCE/
VFR CONDITIONS TODAY WITH A CHANCE OF A LOW/MID LEVEL STRATO-CU
SCT DECK FORMING AFTER 21Z. FAIRLY DRY AIR IN PLACE UNDER HIGH
PRESSURE SO...ANY CLOUDS THAT DO TRY TO FORM TODAY WILL NOT BECOME
THICK ENOUGH FOR BKN CIGS TO FORM. WINDS WILL REMAIN LIGHT AND
FROM THE NORTH. AS HIGH PRESSURE SETTLES IN TONIGHT AND WINDS
BECOME CALM...THE POTENTIAL FOR FOG RETURNS. HAVE INCREASED AMT
AND DURATION OF FOG WITH LOW-END IFR OR LIFR VSBYS POSSIBLE.
&&
.POINT TEMPS/POPS...
DLH -1 30 12 32 / 0 0 10 10
INL -7 29 9 31 / 0 0 10 10
BRD -3 31 12 33 / 0 0 0 10
HYR -5 34 8 34 / 0 0 0 10
ASX 2 32 11 32 / 0 0 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...DAP
AVIATION...DAP
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1226 AM CDT WED MAR 20 2013
.UPDATE...
ISSUED AT 1226 AM CDT WED MAR 20 2013
FCST TEMPS WERE RUNNING A LITTLE TOO COOL AGAINST THE OBSERVED
TEMP CURVES. SO CURRENT OBS WERE MERGED WITH GFS LAMP TEMPS TO
GET THE FCST BACK ON TRACK THE NEXT 3-6 HRS.
SATL SHOWS THE BATCH OF MID-LEVEL CIGS WILL BE OUT OF THE FCST
AREA BY 07Z. THEN JUST SCT MID CLOUDS. FCST HAS THIS GENERAL TREND
SO NO CHANGES NEEDED.
&&
.SHORT TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 357 PM CDT TUE MAR 19 2013
MORNING UPPER AIR ANALYSIS INDICATES LONGWAVE TROUGHING OVER THE
EASTERN-HALF OF THE CONUS WITH RIDGING OVER THE WEST.
NORTHWESTERLY MID AND UPPER LEVEL FLOW PERSISTS OVER THE CENTRAL
PLAINS AS A RESULT. TROPOSPHERIC FLOW OVER OUR AREA MAXES OUT AT
AROUND 120KTS PER 12Z SOUNDING DATA FROM KOAX AND KLBF. WATER
VAPOR IMAGERY ALSO INDICATES A SUBTLE MID LEVEL PERTURBATION OVER
EASTERN MONTANA...MOVING TO THE SOUTHEAST. AT THE SURFACE A TROUGH
IS NOTED EXTENDING FROM WESTERN IOWA INTO SOUTHEASTERN NEBRASKA
AND KANSAS...WITH A COLD FRONT ALSO NOTED OVER THE DAKOTAS. THE
LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM THE NORTHWEST AS
A RESULT.
PROXIMITY SOUNDINGS FROM ACROSS CWA...PER RAP ANALYSIS AND LAPS
DATA...SUGGEST VERY STEEP LOW TO MID LEVEL LAPSE RATES ARE IN
PLACE...WITH NEARLY DRY ADIABATIC LAPSE RATES NOTED FROM THE
SURFACE TO BETWEEN 750MB AND 700MB ACROSS MUCH OF OUR AREA. AS A
RESULT...MODEST SBCAPE VALUES ON THE ORDER OF 100-200J/KG ARE IN
PLACE ACROSS MUCH OF THE CWA. AN EXPANDING CU FIELD AS BEEN NOTED
ON SATELLITE IMAGERY ACROSS MUCH OF NEBRASKA AS A RESULT...WITH
KUEX AND KLNX SUGGESTING ELEVATED PRECIPITATION HAS RESULTED. SOME
OF THIS PRECIPITATION IS MAKING IT TO THE SURFACE IN THE FORM OF
RAIN AND GRAUPEL...BOTH OF WHICH WAS OBSERVED AT THE OFFICE
BETWEEN 19Z AND 20Z. IN ADDITION...A COUPLE OF CG STRIKES HAVE
BEEN DETECTED FROM HALL COUNTY INTO BUFFALO COUNTY WITH SOME OF
THE MORE INTENSE CELLS. WITH ANY OMEGA STILL REMAINING WELL
NORTHWEST OF OUR AREA OVER THE NORTHERN HIGH PLAINS...IN THE
VICINITY OF THE AFOREMENTIONED MID LEVEL PERTURBATION...IT APPEARS
THE CURRENT ACTIVITY IS BEING PROMOTED BY DIABATIC HEATING ALONE.
SO...THIS ACTIVITY SHOULD CONTINUE THROUGH 22Z OR 23Z BEFORE THE
LOSS OF DIABATIC HEATING IS REALIZED LATER THIS EVENING. WENT
AHEAD WITH ISOLATED RAIN AND SNOW SHOWERS...ALONG WITH OCCASIONAL
LIGHTNING...IN THE FORECAST THROUGH 00Z.
THE SAME PROXIMITY SOUNDINGS FROM ACROSS THE CWA ALSO INDICATE
VERY DRY LOWER TROPOSPHERIC AIR IN PLACE ACROSS THE AREA...THUS
RESULTING IN DEEP INVERTED-V SOUNDINGS ACROSS THE ENTIRE CWA.
GIVEN THE ABUNDANT VIRGA NOTED HERE AT THE OFFICE...ALONG WITH THE
UPDRAFT STRENGTH NOTED FROM KUEX THROUGH THE PAST HOUR...FELT IT
PRUDENT TO INTRODUCE BRIEF WIND GUSTS TO AROUND 50 MPH IN THE HWO
THROUGH THIS EVENING.
THE MID LEVEL PERTURBATION...CURRENTLY OVER THE NORTHERN HIGH
PLAINS...IS EXPECTED TO SWEEP OVER OUR AREA TONIGHT. ANY OMEGA IN
ASSOCIATION WITH THIS FEATURE IS EXPECTED TO REMAIN WEAK AND WITH
NO OTHER SIGNIFICANT SOURCE OF LIFT DURING THE SHORT TERM
FORECAST PERIOD...DRY CONDITIONS ARE FORECAST TONIGHT INTO
TOMORROW.
THE PASSAGE OF THE MID LEVEL PERTURBATION WILL ALSO HELP PUSH THE
LOW LEVEL BAROCLINIC ZONE...CURRENTLY OVER THE DAKOTAS...ACROSS
OUR AREA TONIGHT. THIS WILL IN TURN ALLOW A COOLER AIRMASS INTO
OUR REGION THUS RESULTING IN SOMEWHAT COOLER WEDNESDAY MORNING
LOWS WHEN COMPARED TO TUESDAY MORNING. OVERNIGHT LOWS IN THE TEENS
AND 20S ARE CURRENTLY FORECAST FOR TONIGHT AS A RESULT. THE
SURFACE RIDGE IS THEN EXPECTED TO PUSH OFF TO OUR EAST DURING THE
DAY WEDNESDAY...WITH LOW LEVEL RETURN FLOW AND RESULTANT WARM AIR
ADVECTION ALLOWING WEDNESDAY AFTERNOON HIGHS TO CLIMB INTO THE 40S
AND LOWER 50S FOR MOST LOCATIONS ACROSS THE AREA.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 357 PM CDT TUE MAR 19 2013
WEDNESDAY NIGHT THROUGH TUESDAY. PRIMARY FORECAST CONCERN REVOLVES
AROUND A MESSY PATTERN WITH MULTIPLE PRECIPITATION CHANCES
DURING THE LATE WORK WEEK/WEEKEND TIME FRAME.
STILL EXPECTING THE START OF THE LONG TERM PERIOD TO BE DRY...WITH
MODELS IN GOOD AGREEMENT SHOWING NORTHWESTERLY FLOW SET UP IN THE
UPPER LEVELS ACROSS THE REGION WEDNESDAY EVENING INTO THE
OVERNIGHT HOURS...WITH AN ELONGATED LOW PRESSURE SYSTEM SPREAD
FROM THE NORTHEASTERN CONUS THROUGH THE GREAT LAKES...AND
SHORTWAVE RIDGING OVER THE ROCKIES AHEAD OF ANOTHER TROUGH ALONG
THE WEST COAST. AT THE SURFACE...THE CWA SITS BETWEEN A RIDGE OF
HIGH PRESSURE ALONG/JUST EAST OF THE MISSOURI RIVER...AND LOW
PRESSURE EXTENDING FROM THE NORTHERN ROCKIES DOWN INTO SERN
COLORADO...BRINGING SOUTHEASTERLY WINDS TO THE AREA.
AS WE GET INTO EARLY THURSDAY MORNING...STILL SEEING THE MAIN
MID/UPPER LEVEL TROUGH/LOW PRESSURE SYSTEM IN PLACE TO THE
WEST...WITH THE FIRST OF A COUPLE OF DISTURBANCES EJECTED OUT
AHEAD OF IT BEGINNING TO AFFECT THE REGION. MAIN CHANGE WITH THE
MODELS HAS BEEN WITH MORE AGREEMENT BACKING OFF THE COVERAGE OF
PRECIPITATION ACROSS THE CWA...THERE IS PLENTY OF DRIER AIR TO
OVERCOME...AND BETTER CHANCES LOOK TO BE ACROSS EASTERN PORTIONS
OF THE CWA DURING THE DAY ON THURSDAY AS THE MID LEVEL TROUGH AXIS
SWINGS THROUGH AND FRONTOGENETICAL LIFT INCREASES. REALLY TAPERED
BACK POPS...ESP ACROSS THE WRN THIRD OF THE CWA...IT IS POSSIBLE
AFTER 12Z THURSDAY SOME WESTERN LOCATIONS MAY NOT SEE MUCH OF
ANYTHING. DIDNT WANT TO COMPLETELY PULL POPS YET...WANT TO SEE
SOME CONSISTENCY WITH THIS TREND FIRST. DECIDED TO HOLD ON TO THE
MIXED PRECIPITATION ACROSS THE SWRN CWA DURING THE EARLY/MID
MORNING HOURS ON THURSDAY...BUT CONFIDENCE IS NOT HIGH IN IT
OCCURRING. IF PRECIPITATION OCCURS AT ALL IN THAT PART OF THE
CWA...CANT COMPLETELY RULE OUT A BRIEF PERIOD OF MORE OF A
MIX...BUT NOT EXPECTING IT TO AMOUNT TO MUCH.
BUMPED UP HIGH TEMPERATURES ON THURSDAY ONCE AGAIN WITH MODELS
TRENDING TOWARD THE POTENTIAL FOR DRIER CONDITIONS DURING THE
AFTERNOON HOURS...SWRN LOCATIONS COULD REACH INTO THE LOWER/MID
40S. THINK THE NORTHEAST HALF WILL STRUGGLE WITH PRECIP/MORE CLOUD
COVER LINGERING LONGER INTO THE DAY.
SHOULD SEE A LULL IN THE ACTIVITY LATER IN THE DAY THURSDAY AND
INTO THURSDAY EVENING...BUT IT WILL BE A BRIEF BREAK WITH THE
NEXT DISTURBANCE TAKING AIM ON THE REGION. MODELS SHOWING THE MAIN
TROUGH OVER THE NORTHWESTERN CONUS/NRN ROCKIES TRYING TO EVOLVE
INTO A CLOSED CIRCULATION AS ANOTHER 110+KT UPPER LEVEL JET STREAK
DIGS INTO THE WEST COAST. ANOTHER SHORTWAVE DISTURBANCE EJECTED
OUT FROM THIS SYSTEM LOOKS TO BRING ANOTHER CHANCE FOR
PRECIPITATION TO THE CWA. THERE CONTINUE TO BE SOME SLIGHT
DIFFERENCES...BUT MODELS HAVE TRENDED TOWARD MORE AGREEMENT
SHOWING THE TIMING COMING DURING THURSDAY NIGHT INTO THE FIRST
HALF OF THE DAY ON FRIDAY. THINKING THE PRIMARY PRECIPITATION TYPE
FOR MOST WILL BE SNOW...BUT CANT RULE OUT MORE OF A RA/SN
MIX...MAINLY ACROSS THE SOUTHERN CWA. LIKE THURSDAY...TRENDED BACK
POPS ON FRIDAY...THE BETTER CHANCES COME DURING THE 00-12Z FRIDAY
TIME FRAME...WITH VERY LITTLE IN THE WAY OF POPS DURING THE
AFTERNOON HOURS. BECAUSE OF THIS...ALSO BUMPED UP HIGHS ON
FRIDAY...WITH MID 30S IN THE NORTHEAST TO LOWER/MID 40S IN THE
SOUTHWEST.
FRIDAY AFTERNOON AND INTO THE OVERNIGHT HOURS WILL BRING ANOTHER
LULL IN THE ACTIVITY...BEFORE FOCUS QUICKLY TURNS TO A STRONGER
SYSTEM WHICH WILL BRING THE POTENTIAL FOR MORE WIDESPREAD
ACCUMULATING SNOWFALL TO THE REGION. BY EARLY SATURDAY
MORNING...MODELS HAVE STARTED TO COME INTO BETTER AGREEMENT
SHOWING THE DEVELOPMENT OF A LOW PRESSURE SYSTEM OVER THE BORDER
OF MONTANA/CANADA...WHILE A PIECE OF ENERGY SWINGING FURTHER SOUTH
INTO THE ROCKIES DOES THE SAME...AND ITS THIS SOUTHERN ONE WHICH
WILL AFFECT OUR CWA. LIFT WILL BEGIN TO INCREASE ACROSS THE CWA
OUT AHEAD OF THIS SYSTEM LATE FRIDAY NIGHT...ALREADY BRINGING
PRECIPITATION CHANCES TO MAINLY THE WESTERN HALF OF THE CWA.
THROUGH THE DAYTIME HOURS ON SATURDAY THIS UPPER LEVEL LOW WILL
CONTINUE TO PUSH EAST...BRINGING INCREASING PRECIPITATION
CHANCES...AND BY 00Z LOOKS TO BE OVER CENTRAL/ERN PORTIONS OF
COLORADO. THERE ARE SOME TIMING DIFFERENCES...THE ECMWF/GFS ARE IN
PRETTY GOOD AGREEMENT...WITH THE GEM A TOUCH SLOWER. WHAT HAPPENS
THEN THROUGH THE OVERNIGHT HOURS SATURDAY NIGHT AND THEN INTO
SUNDAY IS GOING TO DEPEND ULTIMATELY ON THE PATH/TIMING OF THIS
UPPER LEVEL LOW. THE TIMING/PATH DIFFERENCES BETWEEN THE MODELS
CONTINUE...BUT THEY ALL BRING MORE WIDESPREAD SNOWFALL
ACCUMULATION. THIS IS ESPECIALLY TRUE WITH THE GEM...WHICH IS THE
SLOWEST AND MOST WOUND UP SYSTEM COMPARED TO THE ECMWF/GFS...BUT
ITS PATH IS SOMEWHAT IN BETWEEN THE TWO...TAKING IT MORE THROUGH
CENTRAL KS. THERE ARE PLENTY OF THINGS TO WORK OUT IN THE COMING
DAYS...AND EXPECT MODEL CHANGES...BUT THOSE WITH WEEKEND PLANS
NEED TO KEEP AN EYE ON THIS SYSTEM. AS FAR AS TEMPERATURES
GO...EXPECTING HIGHS TO STRUGGLE TO GET OUT OF THE MID 30S BOTH
SATURDAY AND SUNDAY.
LOOKING AHEAD TO MONDAY AND TUESDAY...KEPT THE FORECAST DRY...BUT
THE MESSY UPPER LEVEL PATTERN REMAINS. MODELS KEEP THE REGION
UNDER THE INFLUENCE OF A BROAD TROUGH...WITH PIECES OF
ENERGY/LOW PRESSURE SYSTEMS ROTATING AROUND EACH OTHER. IN THIS
PATTERN...CERTAINLY WOULNDT BE SEEING MUCH/IF ANY WARM UP...WITH
HIGHS REMAINING IN THE 30S /AVERAGE FOR THIS TIME OF YEAR IS THE
LOWER 50S/...AND ITS NOT OUT OF THE REALM OF POSSIBILITY THAT SOME
OF THIS ENERGY COULD BRING ANOTHER CHANCE FOR PRECIPITATION...ESP
TUESDAY. BUT AT THIS POINT...WITH THERE ALREADY ENOUGH UNCERTAINTY
THROUGH THE WEEKEND...WASNT CONFIDENT ENOUGH TO GO WITH ANY POPS
FOR DAY 7.
&&
.AVIATION...(FOR THE 06Z TAF THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1226 AM CDT WED MAR 20 2013
REST OF TNGT: VFR. A BATCH OF MID-LEVEL CIGS HAS DROPPED S OF THE
TERMINAL AND JUST A FEW-SCT 7-9K FT CLOUDS WILL DRIFT THRU. WINDS
WILL REMAIN NNE BELOW 10 KTS AND GRADUALLY DIMINISHING. AFTER 10Z
WINDS WILL BECOME LGT AND VARIABLE AS HIGH PRES SLIDES THRU.
WED: VFR WITH JUST A COUPLE SKIFFS OF 25K FT CIRRUS. LGT AND
VARIABLE WINDS ORGANIZE FROM THE NW BELOW 10 KTS BEFORE
DIMINISHING AGAIN 21Z-03Z.
WED EVE: VFR MID-LEVEL CIGS INVADE WITH WINDS DEVELOPING FROM THE
ESE AT 10-15 KTS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...BRYANT
LONG TERM...ADO
AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
755 PM EDT THU MAR 21 2013
.SYNOPSIS...
COLD HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTHWEST
THROUGH FRIDAY. A COMPLEX LOW PRESSURE SYSTEM WILL DEVELOP OVER THE
DEEP SOUTH ON SATURDAY...THEN TRACK NORTHEAST INTO THE CAROLINAS AND
MID ATLANTIC ON SUNDAY.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 300 PM THURSDAY...
THROUGH TONIGHT:
SURFACE INSOLATION AND ANOMALOUSLY COLD TEMPS ALOFT (H85 TEMP OF
-10C) DUE TO STRONG COLD ADVECTION EARLIER THIS MORNING HAS RESULTED
IN VERY STEEP LOW-LEVEL LAPSE RATES AND MARGINAL DIURNAL
DESTABILIZATION THIS AFTERNOON...WITH PERHAPS 50-100 J/KG OF SHALLOW
MLCAPE (EQ LEVEL 7-10 KFT) AS OF 18Z. A POTENT SHORTWAVE (PER WV
IMAGERY AND THE LATEST RAP DATA) WAS CENTERED OVER WV/VA AT
18Z...ROUNDING THE BASE OF AN UNSEASONABLY COLD CYCLONIC GYRE
CENTERED OVER NEW ENGLAND. DPVA ASSOCIATED WITH THIS FEATURE WILL
BEGIN TO WANE OVER THE NORTHERN PIEDMONT AND NE COASTAL PLAIN OVER
THE NEXT SEVERAL HOURS AS THE SHORTWAVE PROGRESSES EAST TO THE
DELMARVA. AS A RESULT...ISOLD SNOW SHOWERS ASSOC/W DPVA IN THE
PRESENCE OF MARGINAL INSTABILITY (EXTENDING INTO THE ICE NUCLEATION
ZONE) WILL GRADUALLY WANE AND END OVER THE NEXT FEW HOURS...BETWEEN
18-20Z. NW WINDS WILL INCREASE TO 10-15 MPH SUSTAINED WITH GUSTS UP
TO 25 MPH DURING THE 19-22Z TIME-FRAME AS PRESSURE RISES ENSUE IN
THE WAKE OF THE SHORTWAVE. WINDS WILL GRADUALLY DIMINISH THIS
EVENING INTO TONIGHT AS THE NOCTURNAL INVERSION DEVELOPS AND THE
MSLP GRADIENT WEAKENS FROM W-E. GIVEN CLEAR SKIES AND AN ANOMALOUSLY
COLD/DRY AIRMASS IN PLACE...EXPECT LOWS WELL BELOW NORMAL...PERHAPS
NEAR RECORD COLD FOR MARCH 22. EXACTLY HOW MUCH TEMPS FALL WILL
DEPEND PRIMARILY ON WHEN WINDS DIMINISH...WHICH SHOULD OCCUR EARLIER
IN THE WESTERN PIEDMONT AND LATEST IN THE COASTAL PLAIN. WILL
INDICATE LOWS RANGING FROM THE LOWER TO MID 20S...COLDEST IN RURAL
AND LOW-LYING AREAS...ESP IN THE WESTERN PIEDMONT.
FRIDAY AND FRIDAY NIGHT:
HEIGHTS WILL RISE DURING THE DAY FRIDAY AND FLOW ALOFT WILL BECOME
INCREASINGLY UNIDIRECTIONAL AS THE ANOMALOUSLY COLD CYCLONIC GYRE
CENTERED OVER NEW ENGLAND SHIFTS TOWARD THE CANADIAN MARITIMES.
EXPECT SUNNY SKIES AND WARMER TEMPS THAN TODAY IN ASSOC/W LOW-LEVEL
WARM ADVECTION FROM THE WEST/WSW THROUGHOUT THE DAY. WILL INDICATE
HIGHS IN THE LOWER/MID 50S...SIMILAR TO MOS GUIDANCE...THOUGH IT IS
POSSIBLE THAT A FEW LOCATIONS COULD REACH THE UPPER 50S GIVEN FULL
SUN. EXPECT INCREASING MID/UPPER LEVEL CLOUD COVER FRIDAY NIGHT AS
MOISTURE ADVECTS DOWNSTREAM OF PRECIPITATION EXPECTED TO DEVELOP IN
VICINITY OF A STRENGTHENING FRONTAL ZONE ALONG THE GULF COAST...IN
ADVANCE OF AN UPPER LEVEL TROUGH DIGGING SOUTHEAST INTO THE ROCKIES.
THE BEST LOW-LEVEL MOISTURE RETURN AND WARM ADVECTION IS EXPECTED TO
REMAIN WEST AND SOUTHWEST OF CENTRAL NC...THOUGH IT IS POSSIBLE THAT
MID-LEVEL FRONTOGENESIS MAY ALSO CONTRIBUTE TO ASCENT OVER WESTERN
PORTIONS OF THE STATE. GIVEN THE DRY ANTECEDENT AIRMASS IN PLACE...
AT THIS TIME PREFER TO KEEP THE FORECAST DRY THROUGH FRIDAY NIGHT.
GIVEN INCREASING MID/UPPER LEVEL CLOUD COVER FROM SW-NE...EXPECT
LOWS WARMER THAN TONIGHT...RANGING FROM 30-37F...COOLEST IN RURAL
AND LOW-LYING AREAS EAST AND NE OF THE TRIANGLE. -VINCENT
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
AS OF 1230 PM THURSDAY...
A COLD RAIN EXPECTED LATE SATURDAY THROUGH SUNDAY...
STRONG HIGH LATITUDE BLOCKING DOWNSTREAM AND THE STRONGLY NEGATIVE
PHASE OF BOTH THE ARCTIC OSCILLATION (AO) AND NORTH ATLANTIC
OSCILLATION (NAO) ARE FORECAST TO CONTINUE THROUGH EARLY NEXT
WEEK...KEEPING TEMPERATURES MUCH BELOW NORMAL (LIKELY 15-20 DEGREES)
THROUGH SUNDAY. SEVERAL MID/UPPER DISTURBANCES WILL MOVE EAST OUT OF
THE ROCKIES IN SUPPRESSED FASHION ACROSS THE DEEP SOUTH...WITH THE
POLAR FRONT POSITIONED WELL SOUTH (ALONG THE GULF OF MEXICO).
THE MOST SUBSTANTIAL SHORTWAVE IS FORECAST TO EMERGE ACROSS THE
SOUTHERN PLAINS SUNDAY AND TRACK GENERALLY EAST ACROSS THE TENNESSEE
VALLEY AND CENTRAL APPALACHIANS LATE IN THE WEEKEND INTO EARLY
MONDAY. THIS SHOULD LEAD TO A "MILLER-B" SURFACE LOW PRESSURE
EVOLUTION AND HYBRID COLD AIR DAMMING EVENT SUNDAY INTO EARLY
MONDAY. AHEAD OF THIS WAVE...STRENGTHENING SSW FLOW AND WARM
ADVECTION BETWEEN H925 AND H7 SHOULD SPREAD SOME LIGHT PRECIP ACROSS
THE SOUTHEAST UNITED STATES AS EARLY AS SATURDAY AS THE 850MB FRONT
LIFTS NORTH ACROSS AL/GA/SC. HOWEVER... MODELS CONTINUE TO DISAGREE
ON THE NORTHWARD EXTENT OF MEASURABLE PRECIPITATION.
THE LATEST NAM AND GFS RUNS CONTINUE TO BRING SOME LIGHT MEASURABLE
RAIN INTO OUR WESTERN AND SOUTHERN COUNTIES LATE FRIDAY NIGHT AND
EARLY SATURDAY. THIS WOULD BE ASSOCIATED WITH A LEAD DISTURBANCE AND
PARTIAL THICKNESSES BECOME WARM ENOUGH FOR ALL RAIN. THE EC HAS NOT
BEEN AS AGGRESSIVE WITH THE LIGHT MEASURABLE RAIN WITH THE LEAD WAVE
THIS FAR NORTHEAST...BUT GIVEN THAT THE NAM AND GFS HAVE HAD 4
CONSECUTIVE RUNS WITH THE SAME FORECAST OF LIGHT QPF...WE WILL KEEP
LOW END CHANCES FOR THE SOUTHERN ZONES (ALBEMARLE TO FAYETTEVILLE)
LATE FRIDAY NIGHT INTO MID-DAY SATURDAY. OTHERWISE...GIVEN THE
EXTENT OF THE DRYNESS THE ANTECEDENT AIR MASS IS EXPECTED TO BE...
PREFER TO STICK WITH THE DRY EC OVER THE NORTHERN COUNTIES THROUGH
SATURDAY. HIGHS SATURDAY SHOULD BE FAIRLY UNIFORM ACROSS THE
REGION...WITH THE POSSIBLE LIGHT RAIN EARLY IN THE SOUTH...HIGHS
SHOULD BE ONLY IN THE 50-55 RANGE MOST AREAS. IF SOME LIGHT RAIN IS
MEASURED...TEMPS SHOULD BE EVEN COOLER.
FOR SATURDAY NIGHT AND SUNDAY...EXPECT RAIN TO OVERSPREAD/DEVELOP
NORTHWARD ACROSS OUR REGION WITH THE APPROACH OF THE STRONG
MID/UPPER LEVEL WAVE FROM THE WEST. THE GFS AND NAM CONTINUE TO
DRIVE A STRENGTHENING SURFACE WAVE NE THROUGH THE TENNESSEE VALLEY
INTO THE LOWER OHIO VALLEY SAT NIGHT AND SUNDAY...WITH SECONDARY
BECOMING PRIMARY LOW PRESSURE DEVELOPMENT OFF THE SC COAST SUNDAY.
WITH THE LATTER EXPECTED TO TRACK ALONG THE COAST OF NC LATE SUNDAY
INTO SUNDAY NIGHT...HYBRID CAD WILL BECOME ENTRENCHED OVER CENTRAL
NC THROUGHOUT THE EVENT.
SENSIBLE WEATHER WILL INCLUDE...RAIN DEVELOPING SATURDAY NIGHT WITH
LOWS OF 35-40. RAIN TAPERING TO AREAS OF DRIZZLE LATE SUNDAY. COLD
WITH HIGHS IN THE 40S EXCEPT UPPER 30S NW. QPF ON THE ORDER OF 0.50
TO 0.75 EXPECTED (MAINLY BETWEEN 06Z AND 15Z SUNDAY...TAPERING TO
LIGHT 0.10 AMOUNTS SUNDAY AFTERNOON). STORM TOTALS SHOULD REMAIN
BELOW 1 INCH. STRONG CAA WILL FOLLOW THE STORM INTO NC FROM THE NW
BEGINNING LATE SUNDAY NIGHT. LOWS 35-40 (CLEARING LATE SUNDAY
NIGHT).
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 1230 PM THURSDAY...
STRONG CAA ON MONDAY IN THE REAR OF THE DEPARTING STORM MOVING OUT
INTO THE ATLANTIC WILL KEEP HIGHS ONLY IN THE 40S TO LOWER 50S
(15-20 DEGREES BELOW NORMAL). NW WINDS 15-20 MPH WILL GUST TO 30
MPH. SOME VERY LIGHT SNOW SHOWERS MAY OCCUR ESPECIALLY IN AREAS N-E
OF RALEIGH (NORTHERN COASTAL PLAIN)... BUT NOTHING SIGNIFICANT
EXPECTED. OTHERWISE... PARTLY SUNNY AND WINDY.
CLEAR AND COLD MONDAY NIGHT SHOULD YIELD LOWS IN THE UPPER 20S AND
LOWER 30S (10-15 DEGREES BELOW NORMAL).
TUESDAY THROUGH THURSDAY... A MOSTLY DRY AND CHILLY PATTERN SHOULD
CONTINUE WITH THE DEEP TROUGH EXPECTED TO RELAX A BIT MID-LATE WEEK.
HOWEVER...A STRONG SURFACE HIGH SHOULD EXTEND FROM THE NORTHERN
PLAINS DEEP INTO THE GULF COAST STATES ENSURING CAA WILL BE
DELIVERED DEEP INTO THE SE STATES THROUGH THE PERIOD.
MOSTLY CLEAR/MOSTLY SUNNY SKIES EXPECTED MONDAY NIGHT THROUGH
THURSDAY. LOWS GENERALLY AT OR SLIGHTLY BELOW 32. HIGHS 50-55.
THESE READINGS WILL REMAIN AROUND 15 DEGREES BELOW NORMAL.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AS OF 755 PM THURSDAY...
24 HOUR TAF PERIOD: VFR CONDITIONS WILL PREVAIL THROUGH THE TAF
PERIOD. EXPECT CLEAR SKIES OVERNIGHT WITH WINDS 5-10 KNOTS OUT OF
THE NORTHWEST. ANY REMAINING GUSTS FROM THIS AFTERNOON WILL BE
SUBSIDING OVER THE NEXT HOUR OR TWO. FOR FRIDAY...WINDS WILL PICK UP
TO NEAR 10 KNOTS SUSTAINED WITH LIGHT GUSTING. WINDS WILL SHIFT BY
LATE MORNING OR EARLY AFTERNOON TO MORE OF A WESTERLY OR WEST
SOUTHWESTERLY DIRECTION. SOME HIGH CLOUDS AT 15-20 KFT WILL
OVERSPREAD THE AREA BY THE END OF THE TAF PERIOD.
LONG TERM: VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH FRIDAY
EVENING WITH A CHANCE FOR MVFR CEILINGS EARLY SATURDAY MORNING.
ADVERSE CONDITIONS ARE EXPECTED LATE SATURDAY THROUGH SUNDAY IN
ASSOCIATION WITH A LOW PRESSURE SYSTEM. SUB-VFR CONDITIONS SHOULD
LINGER THROUGH MONDAY BEFORE RETURNING TO VFR LATE MONDAY OR
TUESDAY.
&&
.FIRE WEATHER...
THE SPECIAL WEATHER STATEMENT FOR INCREASED FIRE DANGER WILL BE
ALLOWED TO REMAIN IN EFFECT THROUGH 00Z THIS EVENING IN ASSOC/W RH
VALUES AT OR BELOW 25% AND NW WINDS SUSTAINED AT 10-15 MPH WITH
GUSTS UP TO 25 MPH DURING THE MID/LATE AFTERNOON HOURS. -VINCENT
&&
.RECORD LOWS...
MARCH 22:
RDU: 22F IN 1986
GSO: 22F IN 1986
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...ELLIS
FIRE WEATHER...VINCENT
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
259 PM EDT WED MAR 20 2013
.SYNOPSIS...
A WEAK FRONT WILL MOVE THROUGH EASTERN NORTH CAROLINA TONIGHT. HIGH
PRESSURE WILL BUILD IN THURSDAY NIGHT. A SERIES OF WEAK LOW
PRESSURES WILL MOVE THROUGH THE AREA THROUGH THE WEEKEND. A STRONG
SYSTEM WILL MOVE INTO LATE SUNDAY. HIGH PRESSURE WILL BILD IN MONDAY
NIGHT AND REMAIN THROUGH MIDWEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 245 PM WED...UPPER TROUGH OVER THE PLAINS STATES WILL DEEPEN
AND STRONG SHORT WAVE WILL BRING THE BASE OF THE TROUGH THROUGH
NORTH CAROLINA TONIGHT. MODELS IN GOOD AGREEMENT ON TIMING OF THE
FRONT THROUGH THE AREA...ALTHOUGH RUC IS A LITTLE SLOWER. ALSO SOME
DIFFERENCES IN PTYPE...ECMWF PTYPE FIELD IS CALLING IT FROZEN.
HOWEVER FORECAST SOUNDINGS ALL HAVE ABOVE FREEZING NEAR THE
SURFACE...AND HAVE GONE WITH TEMPERATURES IN THE MID TO UPPER 30S
ACROSS THE AREA TONIGHT. PWS A LESS THAN HALF AN INCH AND SOUNDINGS
DONT COMPLETELY SATURATE. SO WILL KEEP ONLY A SLIGHT CHANCE OF
LIQUID SHOWERS TONIGHT WITH LITTLE TO NO QPF.
&&
.SHORT TERM /THURSDAY/...
AS OF 250 PM WED...SHOWERS WILL MOVE OUT DURING THE MORNING HOURS AS
UPPER LEVEL ENERGY SWINGS THROUGH. 8H TEMPERATURES QUITE COOL FOR
THIS TIME OF YEAR...AND WITH ANOTHER PIECE OF ENERGY SWINGING OVER
THE AREA KEEPING THINGS MIXED UP...TEMPERATURES WILL HAVE A HARD
TIME CLIMBING OUT OF THE MIDDLE 40S DURING THE DAY. LOW PRESSURE
WILL DEEPEN AS IT MOVES OFF THE COAST WITH BREEZES REACHING 15 TO 20
MPH.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
AS OF 240 PM WEDNESDAY...COLD CANADIAN HIGH PRESSURE WILL BUILD OVER
THE AREA WITH BELOW FREEZING TEMPS OVER MUCH OF THE AREA LATE THU
NIGHT INTO EARLY FRI MORN AS WINDS DECOUPLE ESPECIALLY AWAY FROM
THE COAST. THERE IS EVEN THE POSSIBILITY THAT WINDS WILL BECOME
LIGHT ALONG THE OBX WITH A FROST OR FREEZING TEMPERATURES. SINCE
THE SPRING GROWING SEASON HAS ALREADY BEGUN FOR THE OBX...AND
BEGAN TODAY FOR CARTERET AND ONSLOW COUNTIES HAVE ISSUED A FREEZE
WATCH FOR LATE THU NIGHT INTO EARLY FRI MORN FOR THESE AREAS.
UPPER ENERGY WILL MOVE INTO THE FOUR CORNERS REGION WITH
DEVELOPMENT OF A SURFACE LOW LATE FRIDAY. LOW PRESSURE WILL
DEEPEN AS IT MOVES EAST INTO THE MID MISSISSIPPI VALLEY BY EARLY
SUNDAY. ANOTHER SURFACE LOW WILL DEVELOP OVER THE NORTH CENTRAL
GULF OF MEXICO. THIS LOW WILL MOVE UP THE CAROLINA COAST DEEPENING
AS IT MOVES AWAY FROM THE REGION LATE MONDAY. ECMWF NOT AS STRONG
WITH THE DEEPENING AS THE GFS.
WILL CONT WITH LOW POPS FOR THE SOUTHERN COUNTIES FRIDAY
NIGHT/SATURDAY AHEAD OF AN UPR LVL IMPL THEN HIGH CHANCE POPS FOR
SUNDAY AND SUNDAY NIGHT AS THE LOW MOVES UP THE COAST WITH GOOD
LOW LEVEL MOISTURE ADVECTION SPLY ON SUNDAY. MODELS CONT TO SHOW SOME
INSTABILITY NEAR THE COAST ON SUNDAY SO WILL KEEP A SLIGHT CHANCE
OF TSTMS AS WELL.
COOLER THAN NORMAL TEMPS EXPECTED IN THE LONG TERM WITH LOWER 500
MB HEIGHTS CONTINUING. COLDEST TEMPS EXPECTED ON THU NIGHT FRI
MORN FROM THE MID 20S WELL INLAND TO THE LOWER AND MID 30S OBX.
FOR THE REMNDR OF THE LONG TERM PERIOD HIGHS WILL BE IN THE 50S
AND LOWS FROM THE MID 30S INLAND TO THE LWR 40S ON THE COAST.
&&
.AVIATION /18Z WEDNESDAY NIGHT THROUGH SUNDAY/...
SHORT TERM /THROUGH THURSDAY AFTERNOON/...
AS OF 125 PM WED...VFR CONDITIONS EXPECTED THROUGH THE TAF
PERIOD. SOME MID/HIGH CLOUDS ARE STREAMING INTO EASTERN NC FROM
THE SOUTHWEST AHEAD OF A DEVELOPING LOW PRESSURE SYSTEM PROGGED TO
MOVE WELL OFFSHORE. ANTICIPATE CLOUD COVER TO CONTINUE THROUGH
MUCH OF THIS AFTERNOON/EVENING. BRIEF CLEARING IS ANTICIPATED AS
THE SYSTEM MOVES FURTHER OUT TO SEA. HOWEVER..SOME MID LEVEL
CLOUDS ASSOCIATED WITH AN UPPER LEVEL TROUGH WILL PIVOT ACROSS THE
AREA TOMORROW EARLY MORNING. PRECIPITATION WITH THIS SYSTEM SEEMS
MINIMAL AT THIS TIME. WINDS WILL BE VARIABLE THROUGH THE
OVERNIGHT. HOWEVER...AS THE UPPER LEVEL TROUGH MIGRATES OVERHEAD
AND THE STRONG LOW PRESSURE SYSTEM CONTINUES TO MOVE OUT TO
SEA...GUSTY NW WINDS WILL DEVELOP.
LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 240 PM WEDNESDAY...SHOULD SEE GENERALLY VFR CONDITIONS
THURSDAY AND FRIDAY AS COOL CANADIAN HIGH PRESSURE DOMINATES.
MOISTURE RETURNS DURING THE WEEKEND AS LOW PRESSURE MOVES UP THE
NC COAST. EXPECT SUB VFR CONDS IN SHOWERS...ESPECIALLY ON SUNDAY.
&&
.MARINE...
SHORT TERM /THROUGH THURSDAY/...
AS OF 255 PM WED...NORTHEAST WIND OVER THE WATESR THIS AFTERNOON
RUNNING 10 TO 15 KNOTS WITH SEAS 2 TO 3 FEET. AN UPPER LEVEL TROUGH
WILL MOVE THROUGH THE AREA TONIGHT...PUSHING A COLD FRONT THROUGH
THE WATERS AROUND SUNRISE. WINDS AHEAD OF THE FRONT WILL TURN FROM
NORTHEAST TO SOUTHEAST AND THEN SOUTHWEST...THEN BECOME NORTHWEST
AGAIN BEHIND THE FRONT. AS LOW PRESSURE MOVES OFF SHORE IT WILL
START TO DEEPEN...TIGHTENING GRADIENT OVER THE NC COASTAL WATESR
DURING THE AFTERNOON. WIND AND SEAS WILL REACH SCA CRITERIA DURING
THE LATE AFTERNOON HOURS.
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
AS OF 240 PM THURSDAY...NORTHWEST WINDS BEHIND SHORTWAVE SHOULD
CONTINUE IN THE 20 TO 25 KNOT RANGE ACROSS THE NRN AND CNTRL
COASTAL WATERS THROUGH ABOUT 06Z WITH SEAS BUILDING INTO THE 4-7
FT RANGE. SCA HAS BEEN ISSUED FOR THIS AREA. WEAK HIGH PRES WILL
RESULT IN THE WINDS AT 15 KNOTS OR LESS AND SEAS AT 4 FEET OR LESS
FRIDAY AND SATURDAY. LOW PRESSURE THEN MOVES UP THE COAST WITH E
TO NE WINDS INCREASING SUNDAY THEN GUSTY WEST WINDS FOLLOW ON THE
BACKSIDE OF THE LOW ON MONDAY. SEAS ARE EXPECTED TO BE IN THE 4-7
FOOT RANGE FOR SUNDAY AND MONDAY.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...FREEZE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY MORNING
FOR NCZ095-098-103-104.
MARINE...SMALL CRAFT ADVISORY FROM 1 PM THURSDAY TO 2 AM EDT FRIDAY FOR
AMZ150-152-154.
&&
$$
SYNOPSIS...CGG
NEAR TERM...CGG
SHORT TERM...CGG
LONG TERM...JAC
AVIATION...JAC/LEP
MARINE...CGG/JAC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
846 PM CDT THU MAR 21 2013
.DISCUSSION...LATEST RADAR IMAGERY/SURFACE OBSERVATIONS CONTINUE TO
SHOW AN AREA OF LIGHT SNOW IN THE WEST WITH LITTLE MOVEMENT EASTBOUND.
THE RAP MAINTAINS A VERY SLOW PROGRESSION EAST THROUGH FRIDAY AFTERNOON.
WATER VAPOR IMAGERY SHOWS AN UPPER LOW BEGINNING TO FORM OVER
NORTH CENTRAL MONTANA WITH A SURFACE LOW BASICALLY UNDERNEATH THE
UPPER LOW FORMATION. THE SURFACE/UPPER AIR LOW IS FORECAST TO MOVE
TO NEAR BAKER MONTANA BY 12Z FRIDAY. HENCE...EXPECT A CONTINUATION
OF A FAIRLY SHARP DELINEATION FROM SNOW TO NO SNOW. WILL AWAIT THE
00Z NAM...BUT TRENDS ARE FOR ANOTHER DELAY OF THE LIGHT SNOW
SHIELD INTO CENTRAL NORTH DAKOTA...NOT UNTIL MID TO LATE MORNING FOR
KBIS/KMOT. REST OF FORECAST REMAINS ON TRACK.
&&
.AVIATION...LIGHT SNOW ACROSS THE WESTERN AERODROMES OF KISN/KDIK
PER LATEST SURFACE OBSERVATIONS/RADAR IMAGERY WITH MVFR/IFR CIGS/VSBYS
THROUGH FRIDAY MORNING. THE CENTRAL AERODROMES OF KMOT AND KBIS
WILL REMAIN VFR UNTIL 09Z FRIDAY...WITH MVFR CIGS DEVELOPING
THEREAFTER. LIGHT SNOW/IFR VSBYS WILL HOLD OFF UNTIL 13Z TO 16Z
FOR KBIS NORTH TO KMOT. KJMS WILL REMAIN VFR THROUGH 15Z FRIDAY
BEFORE EXPERIENCING MVFR CIGS. THE LIGHT SNOW IS NOT EXPECTED AT
KJMS UNTIL 22Z FRIDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION/AVIATION...KS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1151 PM EDT THU MAR 21 2013
.SYNOPSIS...
AN UPPER LEVEL LOW OVER SOUTHEAST CANADA WILL REMAIN ANCHORED
NORTH OF PENNSYLVANIA THROUGH THE REST OF THE WORKWEEK. GUSTY
WEST TO NORTHWEST WINDS WILL CONTINUE TO FILTER COLD AIR INTO THE
REGION. THIS WILL ALSO PRODUCE OCCASIONAL SNOW SHOWERS ACROSS THE
WESTERN MOUNTAINS. A STORM SYSTEM MAY MOVE OUT OF THE MID-
MISSISSIPPI VALLEY LATER THIS WEEKEND AND COULD BRING ANOTHER
ROUND OF WINTRY PRECIPITATION TO THE REGION LATE SUNDAY NIGHT AND
MONDAY. THERE IS NO WARM-UP IN SIGHT...AS THE MONTH OF MARCH IS
LIKELY TO END ON A WINTRY NOTE.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
MINOR CHANGES MADE FOR THIS 0230Z UPDATE.
UPR SHORTWAVE AND SFC TROUGH AXIS MOVING ACROSS WRN PA LATE THIS
EVENING. MEAN 925-850 MB FLOW OF ABOUT 30 KTS /AND VEERING TO THE
NW/ WILL DRIVE MULTIPLE BANDS OF SNOW SHOWERS AND SOME BRIEFLY
HEAVY SQUALLS WELL INLAND ACROSS THE ALLEGHENY PLATEAU OVERNIGHT.
THIS WILL BRING A LIGHT ACCUMULATION ACROSS MOST OF THE HIGHER
TERRAIN OF WRN AND NRN PENN.
WILL KEEP THE LAKE EFFECT SNOW ADVISORY GOING FOR WARREN COUNTY
THROUGH 16Z FRIDAY WHERE ANOTHER 2 TO 3 INCHES IS LIKELY...
BRINGING 36-HOUR SNOW TOTALS UP TO 4-7 INCHES ACROSS THE SNOWBELT
OF NW WARREN COUNTY.
SCATTERED SNOW SHOWERS JUST EAST OF THE ALLEGHENY FRONT WILL
BRING A LIGHT COATING TO SOME LOCATIONS. CLEAR TO PARTLY CLOUDY
SKIES WILL OCCUR EARLY TONIGHT ACROSS THE LOWER SUSQ
VALLEY...FOLLOWED BY MOSTLY CLOUDY SKIES AFTER MIDNIGHT WITH
FLURRIES AND PERHAPS A BRIEF SNOW SHOWERS. WITH NOTHING
ANOTHER CHILLY...BELOW NORMAL NIGHT IS IN STORE FOR CENTRAL
PENNSYLVANIA...WITH LOW TEMPERATURES RANGING FROM THE MID TEENS
ACROSS THE NORTHERN WESTERN MOUNTAINS...TO THE LOWER 20S IN THE
SOUTHEAST.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
LAKE EFFECT SNOW SHOWERS WILL PERSIST NEAR...AND IMMEDIATELY
DOWNWIND FROM LAKE ERIE OVER WARREN COUNTY. EXPECT A TOTAL OF 4
TO 7 INCHES TO ACCUMULATE BY LATE FRIDAY MORNING IN THE ADVISORY
AREA...WITH LESSER AMOUNTS TO THE SOUTH AND EAST. WEST CENTRAL AND
NORTH CENTRAL MOUNTAIN AREAS WILL GENERALLY SEE A COATING TO 2
INCHES THROUGH FRIDAY MORNING.
UPSLOPE SNOW SHOWERS WILL ALSO CONTINUE THROUGH FRIDAY MORNING
WITH SNOW ACCUMULATIONS OF 1-2 INCHES POSSIBLE OVER THE LAUREL
HIGHLANDS.
SNOW SHOWERS WILL SLOWLY DECREASE LATE FRIDAY AS SFC HIGH PRESSURE
APPROACHES FROM THE OHIO VALLEY. WHILE SCATTERED ACTIVITY IS STILL
EXPECTED INTO FRIDAY NIGHT...BELIEVE THE SIGNIFICANT ACCUMS WILL
BE OVER BY FRIDAY AFTERNOON. MAXES ON FRIDAY WILL CONTINUE TO
BE WELL BELOW NORMAL...RANGING FROM THE UPPER 20S OVER THE
NORTHERN TIER TO THE LOWER TO MIDDLE 40S ACROSS THE SOUTHEAST.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
A SHORT PERIOD OF RISING HEIGHTS WILL MOVE ACROSS PA OVER THE
WEEKEND HELPING TO BRING SNOW SHOWER ACTIVITY TO AN END. THE
SHORTWAVE RIDGE IS AHEAD OF EXPECTED SIGNIFICANT LONGWAVE TROF
DEVELOPMENT FORECAST TO TAKE PLACE ACROSS THE PLAINS OVER THE
WEEKEND AS ENERGY DIVES SOUTH FROM CANADA. THE LARGE-SCALE PATTERN
DOES FAVOR DEVELOPMENT OF A SFC LOW OVER THE MID MS VALLEY AND A
MILLER TYPE-B SCENARIO AFTER THAT AS THE UPPER TROUGH SWINGS TO
THE EAST. BUT...THE DEVIL REMAINS IN THE DETAILS. SO...EYES ARE
CENTERED ON PERHAPS ANOTHER LATE WINTER/EARLY SPRING STORM FOR PA
FROM PERHAPS LATE SUNDAY INTO MONDAY NIGHT. MOST MDLS AND ENSEMBLE
MEMBERS DO BRING SOME PRECIP INTO AT LEAST SRN HALF OF PA FROM
THIS SYSTEM. HOWEVER...THE BIG TROUBLES REMAIN TIMING...NORTHWARD
EXTENT OF PRECIP DUE TO TIMING OF LOW TRANSFER...AND OF COURSE
TEMPS AND P-TYPES DURING THE PRECIP. IN OTHER WORDS...EVERYTHING
IS STILL UNCERTAIN. DID HAVE ENOUGH CONFIDENCE TO MAKE POPS AROUND
50 PCT IN THE S FOR TWO PERIODS...BUT IT IS STILL A DAY 5-6
/POTENTIAL/ STORM. PLENTY OF TIME FOR THE PROGS TO WAGGLE ALL
DIFFERENT DIRECTIONS FOR MANY DAYS.
&&
.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
A COLD NORTHWEST FLOW WILL GATHER MOISTURE FROM THE GREAT LAKES
AND DEPOSIT IT AS SNOW SHOWERS ACROSS THE ALLEGHENY MOUNTAINS
TONIGHT AND FRIDAY. SOME OF THE HEAVIEST SNOW SHOWERS WITH
IFR VSBYS WILL LIKELY OCCUR BTWN 04Z-08Z AT JST WITH PASSAGE OF A
WEAK SFC TROUGH. LATEST RUC SHOWS A TONGUE OF HIGHER LOW LVL
MOISTURE ALONG THIS BOUNDARY SAGGING SOUTH INTO THE LAUREL
HIGHLANDS DURING THIS TIME PERIOD. DRYING...DOWNSLOPING FLOW
SHOULD RESULT IN MUCH BETTER FLYING CONDS OVERNIGHT EAST OF THE
MTNS. CAN/T RULE OUT BRIEF VSBY RESTRICTIONS OVERNIGHT AT
AOO/UNV/IPT...WHILE CONDS AT MDT AND LNS APPEAR VERY LIKELY TO
REMAIN VFR.
EXPECT DIMINISHING -SHSN OVR THE W MTNS ON FRIDAY...AS INVERSION
HEIGHTS LOWER WITH APPROACH OF SFC HIGH. STILL...OCNL MVFR
CIGS/VSBYS REMAIN POSSIBLE AT BFD THRU FRI EVENING. AN INTENSE LOW
PRES SYSTEM OVR THE CANADIAN MARITIMES WILL CONTINUE TO BUFFET THE
AREA WITH A GUSTY WNW WINDS. ALTHOUGH THE GUSTS MAY DIMINISH A BIT
OVERNIGHT...BUFKIT SOUNDINGS SUPPORT WIDESPREAD GUSTS ARND 25KTS
DURING LATE FRI AM AND AFTERNOON.
OUTLOOK...
SAT...NO SIG WX EXPECTED.
SUN...SNOW POSS LATE ACROSS THE SOUTH.
MON...SNOW POSS...ESP SOUTH.
TUE...SNOW POSS...ESP LAUREL HIGHLANDS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
LAKE EFFECT SNOW ADVISORY UNTIL NOON EDT FRIDAY FOR PAZ004.
&&
$$
SYNOPSIS...DANGELO/DEVOIR/COLBERT
NEAR TERM...LAMBERT/COLBERT
SHORT TERM...DEVOIR/LA CORTE/LAMBERT
LONG TERM...DANGELO/CERU
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
821 PM CDT THU MAR 21 2013
.UPDATE...
WEAK MOISTURE CONVERGENCE AND LIMITED INSTABILITY PREVENTED
THUNDERSTORM DEVELOPMENT ALONG THE DRY LINE THIS AFTERNOON/EARLY
THIS EVENING. NOW WITH THE LOSS OF SURFACE HEATING...STORM CHANCES
ALONG THE DRY LINE HAVE DECREASED SIGNIFICANTLY. THERE IS STILL A
CHANCE OF SOME ELEVATED SHOWERS AND THUNDERSTORMS ACROSS THE
NORTHERN HALF OF NORTH TEXAS WITH THE BEST STORM CHANCES ACROSS
THE NORTHEAST ZONES JUST NORTH OF A WARM FRONT. FURTHER
SOUTH...SOME WARM AIR ADVECTION SHOWERS ARE POSSIBLE...ESPECIALLY
TOWARD MORNING.
FOR THIS UPDATE...WE WILL LOWER EVENING POPS IN ALL ZONES AND MAKE
SOME MINOR WIND/CLOUD COVER AND HOURLY TEMP/DEW POINT ADJUSTMENTS.
79
&&
.AVIATION...
CLOUD COVER HAS PREVENTED GOOD SURFACE HEATING EAST OF THE DRY
LINE AND CHANCES OF CONVECTION THIS EVENING NEAR DFW AIRPORTS
LOOK CLOSE TO ZERO. GOOD MOISTURE RETURN THOUGH...AND MVFR
CONDITIONS ARE EXPECTED TO DEVELOP LATER THIS EVENING AS CIGS
CONTINUE TO LOWER. WITH FROPA NEAR SUNRISE...MVFR CIGS WILL
LIKELY LINGER MUCH OF THE DAY...WITH A LIFT TO VFR FRIDAY
AFTERNOON AND THEN MORE MVFR AFTER MIDNIGHT. 84
&&
.PREV DISCUSSION... /ISSUED 319 PM CDT THU MAR 21 2013/
BREEZY AND MOSTLY CLOUDY CONDITIONS CONTINUE ACROSS THE REGION
THIS EVENING BUT SOME CHANGES ARE STILL EXPECTED BY THE LATE
AFTERNOON AND EVENING HOURS. THE SURFACE LOW REMAINS OVER THE
TEXAS PANHANDLE WITH THE LEADING EDGE OF THE DRYLINE NOW LOCATED
ROUGHLY ALONG A LINE FROM VERNON TO SAN ANGELO. DEWPOINTS CONTINUE
TO INCREASE INTO THE LOWER 50S AHEAD OF THE DRYLINE BUT
INSTABILITY IS STILL LACKING. SATELLITE IMAGERY DEPICTS EVIDENCE
OF INCREASING LIFT APPROACHING THE REGION FROM THE WEST. SOME LOW
LEVEL CUMULUS HAS NOW DEVELOPED IN NORTHWEST TEXAS AND SOUTHWEST
OKLAHOMA AND MID LEVEL CLOUDS OVER WEST CENTRAL TEXAS ARE
LOOKING MORE ROBUST. INITIATION IS STILL POSSIBLE NEAR THE DRYLINE
LATE THIS AFTERNOON...AMONGST BREAKS IN THE MID LEVEL CLOUD DECK
BUT THE WINDOW FOR SEVERE POTENTIAL IS DECREASING. INITIATION NEAR
THE DRYLINE JUST WEST OF OUR CWA LIKELY WILL NOT BE UNTIL AFTER 5
PM AND THE SEVERE THREAT WILL BE DIMINISHING WITH THE LOSS OF
HEATING BY 8-9 PM. CONSIDERING THE LATEST TRENDS...WITH THE MID
LEVEL CLOUD COVER THAT IS STRETCHING BACK WEST...SBCAPES NEAR 1000
J/KG AS PREVIOUSLY PREDICTED MAY BE TOO HIGH AND VALUES WILL
REMAIN CLOSER TO 500-800 J/KG. CONVERGENCE ALONG THE DRYLINE IS
NOT VERY GOOD AT THIS TIME AS THE WINDS AHEAD OF THE DRYLINE ARE
ALSO FROM THE SOUTHWEST. THE RAP SHOWS THE SURFACE LOW REMAINING
IN THE TEXAS PANHANDLE FOR THE NEXT FEW HOURS WHICH MEANS THE SURFACE
WINDS WILL LIKELY NOT HAVE A CHANCE TO BACK AS THE DRYLINE MOVES
CLOSER. HOWEVER...WITH STRONG SHEAR...LIFT FROM A SERIES OF
SHORTWAVES MOVING NEAR THE REGION AND THE POTENTIAL FOR INCREASING
INSTABILITY OVER THE NEXT FEW HOURS...STILL EXPECT TO SEE A FEW
THUNDERSTORMS OVER OUR NORTHWESTERN COUNTIES WITH A FEW STRONG TO
SEVERE STORMS POSSIBLE. ANY STORMS THAT DO DEVELOP WILL LIKELY
MOVE EAST OR SOUTHEAST. LARGE HAIL AND DAMAGING WINDS WILL BE THE
MAIN THREATS.
EXPECT THE THUNDERSTORM ACTIVITY TO WANE FAIRLY QUICKLY AROUND OR
AFTER SUNSET BUT ADDITIONAL SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE OVER THE NORTHERN HALF OF THE REGION OVERNIGHT. THE
HIGHEST CHANCES FOR RAIN CONTINUE TO BE OVER THE NORTHEASTERN
COUNTIES. CANNOT RULE OUT A STRONG STORM OR TWO PRODUCING SMALL
HAIL AND/OR GUSTY WINDS BUT THE INSTABILITY OVERNIGHT IS FAIRLY
WEAK. A COLD FRONT WILL MOVE INTO THE REGION LATE TONIGHT AND
CONTINUE TO PROGRESS SOUTH THROUGH THE DAY TOMORROW. THERE
CONTINUES TO BE A CHANCE FOR RAIN AND ISOLATED THUNDERSTORMS OVER
THE EASTERN HALF OF THE REGION TOMORROW. WE COULD SEE A STRONG
STORM OR TWO OVER OUR FAR SOUTHEASTERN COUNTIES TOMORROW AFTERNOON
AHEAD OF THE FRONT.
THE FRONT WILL STALL JUST SOUTH OF THE CWA FRIDAY NIGHT AND THEN
RETREAT NORTH AS A WARM FRONT ON SATURDAY. AS THE WARM FRONT LIFTS
NORTH...WARM AIR ADVECTION OVER THE COOL SURFACE LAYER WILL RESULT
IN SCATTERED RAIN ACTIVITY THROUGHOUT THE DAY WITH ISOLATED
THUNDERSTORMS POSSIBLE. HIGHEST RAIN CHANCES WILL BE OVER THE
EASTERN HALF OF THE REGION. A STRONGER COLD FRONT WILL PUSH ACROSS
THE REGION SATURDAY NIGHT. THE RAIN WILL BE ENDING FROM WEST TO
EAST DURING THE DAY AS A DRYLINE MOVES ACROSS THE REGION. MUCH
COOLER AND DRIER AIR WILL SETTLE INTO THE REGION FOR SEVERAL DAYS
WITH TEMPERATURES FALLING BELOW NORMAL FOR AT LEAST THE FIRST HALF
OF NEXT WEEK. A FREEZE IS NOT EXPECTED REGION-WIDE ON ANY GIVEN
NIGHT BUT NEAR FREEZING TEMPERATURES WILL BE POSSIBLE MAINLY OVER
THE NORTHWESTERN HALF OF THE CWA SUNDAY AND MONDAY NIGHTS. TEMPERATURES
WILL START TO WARM LATER IN THE WEEK AND THE GFS IS MUCH FASTER TO
WARM TEMPERATURES THAN THE ECMWF.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 57 64 47 68 42 / 20 20 20 50 10
WACO, TX 62 71 50 74 42 / 10 20 20 50 5
PARIS, TX 48 58 45 58 37 / 50 30 20 50 20
DENTON, TX 51 60 45 65 39 / 30 20 20 40 10
MCKINNEY, TX 54 60 45 62 40 / 40 20 20 50 10
DALLAS, TX 58 64 48 68 43 / 20 20 20 50 10
TERRELL, TX 58 64 48 65 42 / 30 30 20 50 10
CORSICANA, TX 62 71 50 69 43 / 20 20 20 50 10
TEMPLE, TX 62 76 52 76 41 / 10 20 20 40 5
MINERAL WELLS, TX 50 63 46 74 39 / 20 10 20 30 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
84/79
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
629 PM CDT THU MAR 21 2013
.AVIATION...
CLOUD COVER HAS PREVENTED GOOD SURFACE HEATING EAST OF THE DRY
LINE AND CHANCES OF CONVECTION THIS EVENING NEAR DFW AIRPORTS
LOOK CLOSE TO ZERO. GOOD MOISTURE RETURN THOUGH...AND MVFR
CONDITIONS ARE EXPECTED TO DEVELOP LATER THIS EVENING AS CIGS
CONTINUE TO LOWER. WITH FROPA NEAR SUNRISE...MVFR CIGS WILL
LIKELY LINGER MUCH OF THE DAY...WITH A LIFT TO VFR FRIDAY
AFTERNOON AND THEN MORE MVFR AFTER MIDNIGHT. 84
&&
.PREV DISCUSSION... /ISSUED 319 PM CDT THU MAR 21 2013/
BREEZY AND MOSTLY CLOUDY CONDITIONS CONTINUE ACROSS THE REGION
THIS EVENING BUT SOME CHANGES ARE STILL EXPECTED BY THE LATE
AFTERNOON AND EVENING HOURS. THE SURFACE LOW REMAINS OVER THE
TEXAS PANHANDLE WITH THE LEADING EDGE OF THE DRYLINE NOW LOCATED
ROUGHLY ALONG A LINE FROM VERNON TO SAN ANGELO. DEWPOINTS CONTINUE
TO INCREASE INTO THE LOWER 50S AHEAD OF THE DRYLINE BUT
INSTABILITY IS STILL LACKING. SATELLITE IMAGERY DEPICTS EVIDENCE
OF INCREASING LIFT APPROACHING THE REGION FROM THE WEST. SOME LOW
LEVEL CUMULUS HAS NOW DEVELOPED IN NORTHWEST TEXAS AND SOUTHWEST
OKLAHOMA AND MID LEVEL CLOUDS OVER WEST CENTRAL TEXAS ARE
LOOKING MORE ROBUST. INITIATION IS STILL POSSIBLE NEAR THE DRYLINE
LATE THIS AFTERNOON...AMONGST BREAKS IN THE MID LEVEL CLOUD DECK
BUT THE WINDOW FOR SEVERE POTENTIAL IS DECREASING. INITIATION NEAR
THE DRYLINE JUST WEST OF OUR CWA LIKELY WILL NOT BE UNTIL AFTER 5
PM AND THE SEVERE THREAT WILL BE DIMINISHING WITH THE LOSS OF
HEATING BY 8-9 PM. CONSIDERING THE LATEST TRENDS...WITH THE MID
LEVEL CLOUD COVER THAT IS STRETCHING BACK WEST...SBCAPES NEAR 1000
J/KG AS PREVIOUSLY PREDICTED MAY BE TOO HIGH AND VALUES WILL
REMAIN CLOSER TO 500-800 J/KG. CONVERGENCE ALONG THE DRYLINE IS
NOT VERY GOOD AT THIS TIME AS THE WINDS AHEAD OF THE DRYLINE ARE
ALSO FROM THE SOUTHWEST. THE RAP SHOWS THE SURFACE LOW REMAINING
IN THE TEXAS PANHANDLE FOR THE NEXT FEW HOURS WHICH MEANS THE SURFACE
WINDS WILL LIKELY NOT HAVE A CHANCE TO BACK AS THE DRYLINE MOVES
CLOSER. HOWEVER...WITH STRONG SHEAR...LIFT FROM A SERIES OF
SHORTWAVES MOVING NEAR THE REGION AND THE POTENTIAL FOR INCREASING
INSTABILITY OVER THE NEXT FEW HOURS...STILL EXPECT TO SEE A FEW
THUNDERSTORMS OVER OUR NORTHWESTERN COUNTIES WITH A FEW STRONG TO
SEVERE STORMS POSSIBLE. ANY STORMS THAT DO DEVELOP WILL LIKELY
MOVE EAST OR SOUTHEAST. LARGE HAIL AND DAMAGING WINDS WILL BE THE
MAIN THREATS.
EXPECT THE THUNDERSTORM ACTIVITY TO WANE FAIRLY QUICKLY AROUND OR
AFTER SUNSET BUT ADDITIONAL SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE OVER THE NORTHERN HALF OF THE REGION OVERNIGHT. THE
HIGHEST CHANCES FOR RAIN CONTINUE TO BE OVER THE NORTHEASTERN
COUNTIES. CANNOT RULE OUT A STRONG STORM OR TWO PRODUCING SMALL
HAIL AND/OR GUSTY WINDS BUT THE INSTABILITY OVERNIGHT IS FAIRLY
WEAK. A COLD FRONT WILL MOVE INTO THE REGION LATE TONIGHT AND
CONTINUE TO PROGRESS SOUTH THROUGH THE DAY TOMORROW. THERE
CONTINUES TO BE A CHANCE FOR RAIN AND ISOLATED THUNDERSTORMS OVER
THE EASTERN HALF OF THE REGION TOMORROW. WE COULD SEE A STRONG
STORM OR TWO OVER OUR FAR SOUTHEASTERN COUNTIES TOMORROW AFTERNOON
AHEAD OF THE FRONT.
THE FRONT WILL STALL JUST SOUTH OF THE CWA FRIDAY NIGHT AND THEN
RETREAT NORTH AS A WARM FRONT ON SATURDAY. AS THE WARM FRONT LIFTS
NORTH...WARM AIR ADVECTION OVER THE COOL SURFACE LAYER WILL RESULT
IN SCATTERED RAIN ACTIVITY THROUGHOUT THE DAY WITH ISOLATED
THUNDERSTORMS POSSIBLE. HIGHEST RAIN CHANCES WILL BE OVER THE
EASTERN HALF OF THE REGION. A STRONGER COLD FRONT WILL PUSH ACROSS
THE REGION SATURDAY NIGHT. THE RAIN WILL BE ENDING FROM WEST TO
EAST DURING THE DAY AS A DRYLINE MOVES ACROSS THE REGION. MUCH
COOLER AND DRIER AIR WILL SETTLE INTO THE REGION FOR SEVERAL DAYS
WITH TEMPERATURES FALLING BELOW NORMAL FOR AT LEAST THE FIRST HALF
OF NEXT WEEK. A FREEZE IS NOT EXPECTED REGION-WIDE ON ANY GIVEN
NIGHT BUT NEAR FREEZING TEMPERATURES WILL BE POSSIBLE MAINLY OVER
THE NORTHWESTERN HALF OF THE CWA SUNDAY AND MONDAY NIGHTS. TEMPERATURES
WILL START TO WARM LATER IN THE WEEK AND THE GFS IS MUCH FASTER TO
WARM TEMPERATURES THAN THE ECMWF.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 57 64 47 68 42 / 30 20 20 50 10
WACO, TX 62 71 50 74 42 / 10 20 20 50 5
PARIS, TX 48 58 45 58 37 / 60 30 20 50 20
DENTON, TX 51 60 45 65 39 / 40 20 20 40 10
MCKINNEY, TX 54 60 45 62 40 / 50 20 20 50 10
DALLAS, TX 58 64 48 68 43 / 30 20 20 50 10
TERRELL, TX 58 64 48 65 42 / 30 30 20 50 10
CORSICANA, TX 62 71 50 69 43 / 20 20 20 50 10
TEMPLE, TX 62 76 52 76 41 / 10 20 20 40 5
MINERAL WELLS, TX 50 63 46 74 39 / 40 10 20 30 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/
YOU CAN SEE AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML
...CORRECT TYPO IN THE AVIATION FORECAST DISCUSSION.
.SHORT TERM...TONIGHT AND THURSDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A BROAD AND
ELONGATED UPPER LEVEL LOW PRESSURE SYSTEM SPINNING FROM THE CENTRAL
GREAT LAKES TO NEW ENGLAND EARLY THIS AFTERNOON. CLOUDS HAVE BEEN
SPREADING SOUTH ACROSS THE UPPER PENINSULA AND NORTHERN WISCONSIN SO
FAR TODAY...AS A RESULT OF SHORTWAVE LOBES ROTATING AROUND THE
PARENT VORTEX...AND ALSO STEEPENING LOW LEVEL LAPSE RATES. THESE
CONDITIONS ALSO PROMOTE CONDITIONS FOR SIGNIFICANT LAKE EFFECT
SNOWS...WHICH ARE OCCURRING WITHIN THE SNOW BELTS OF THE WESTERN
UPPER PENINSULA. IN FACT...IRONWOOD HAS OSCILLATED BETWEEN 1/2SM
AND 3/4SM FOR MUCH OF THE DAY. LAKE EFFECT POTENTIAL IS THE MAIN
FORECAST CONCERN OVER THE NEXT 24 HOURS AS WIND TRAJECTORIES BECOME
MORE FAVORABLE FOR N-C WISCONSIN.
TONIGHT...SHORTWAVE TROUGH WILL DIVE SOUTH ACROSS CENTRAL AND
SOUTHERN WISCONSIN THIS EVENING...ON THE WESTERN FLANK OF THE UPPER
LOW. NOT SOLD THAT PRECIP WILL TURN OFF AT SUNSET...THOUGH DIURNAL
INSTABILITY WILL BE LOST. WILL KEEP LIGHT SNOW SHOWERS AND FLURRIES
GOING FOR A GOOD CHUNK OF THE EVENING. BEHIND THE SHORTWAVE...LOW
LEVEL WINDS TURN TO THE NNW. WIND TRAJECTORIES LOOK REALLY GOOD FOR
A SOLID LAKE EFFECT EVENT FOR N-C WISCONSIN. THERMAL PROFILES ARE
ALSO IN THE OPTIMAL DENDRITIC GROWTH ZONE THROUGH THE NIGHT...AND
THERE IS SUFFICIENT MOISTURE IN THE 850-700MB LAYER AS WELL. ON THE
MINUS SIDE...SUBSIDENCE WILL BE INCREASING THROUGH THE NIGHT AND
LAKE INDUCED CAPE WILL GRADUALLY DIMINISH. THE LOCAL LAKE EFFECT
PARAMETER DOES SHOW A SLIGHT DIMINISHING TREND TONIGHT...BUT NOT
THAT SIGNIFICANT. A LIMITING FACTOR MAY BE THE 15 KT BL WINDS...IN
WHICH THE NORTHERN PART OF VILAS COUNTY GETS ADVISORY CRITERIA
SNOW...AND THE SOUTHERN HALF DOES NOT. SO THINK WILL GO WITHOUT AN
ADVISORY AND ISSUE AN SPS FOR THE COUNTY TONIGHT...AND WILL
HIGHLIGHT THAT SEVERAL INCHES OF SNOW ARE POSSIBLE ACROSS THE
NORTHERN PART OF THE COUNTY. PARTIAL CLEARING SHOULD OCCUR OUTSIDE
THE LAKE EFFECT BELT DURING THE OVERNIGHT HOURS...BUT DO NOT THINK
WILL SEE DECOUPLING. AS A RESULT...LOW TEMPS WILL BE COMPARABLE TO
LAST NIGHTS LOWS.
THURSDAY...LAKE EFFECT SNOW SHOWERS WILL CONTINUE OVER N-C WISCONSIN
THROUGH EARLY AFTERNOON...BUT SHOULD DIMINISH AS DRY AIR INVADES
FROM THE NORTH. ELSEWHERE...AFTER A MOSTLY CLEAR TO PARTLY CLOUDY
START TO THE DAY...CLOUDS SHOULD BE INCREASING BY LATE MORNING OR
EARLY AFTERNOON AS WILL STILL HAVE PLENTY OF LOW LEVEL MOISTURE AND
STEEP LOW LEVEL LAPSE RATES AROUND. INCREASED CLOUD COVER...BUT
KEPT THE SNOW CHANCES CONFINED TO THE SNOW BELT. HIGHS SEVERAL
DEGREES WARMER THAN TODAY WITH HIGHS MAINLY IN THE MID TO UPPER 20S.
.LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY...MAIN FCST
CONCERN IS TEMPERATURES.
A LARGE UPPER LEVEL LOW WILL RESIDE OVER EASTERN CANADA AND THE
EASTERN GREAT LAKES REGION EARLY IN THE PERIOD...BUT WILL SHIFT
EAST BY FRI/SAT...ALLOWING WEAK RIDGING TO DEVELOP OVER WI. A
LARGE CANADIAN SFC HIGH WILL RIDGE INTO THE WESTERN GREAT LAKES
DURING THIS PERIOD...BRINGING DRY...BUT CONTINUED COOL CONDITIONS.
WITH LOW-LEVEL WINDS TURNING NNE-NE...CONSIDERED THE POSSIBILITY
OF SOME LIGHT LAKE EFFECT SNOW SHOWERS OR FLURRIES IN EASTERN WI...
BUT WINDS ARE VERY LIGHT ON FRIDAY NIGHT...AND MOISTURE AND
INSTABILITY ARE NOT VERY FAVORABLE ON SATURDAY...SO KEPT A DRY
FCST INTACT.
THE UPPER PATTERN WILL TRANSITION BACK TO A BROAD UPPER TROF LATE
IN THE WEEKEND...AND CONTINUING THROUGH THE MIDDLE OF NEXT WEEK.
THE ONLY SIGNIFICANT STORM OF THE WEEK IS A LOW PRESSURE SYSTEM
WHICH MOVES THROUGH THE SOUTHERN PLAINS ON SATURDAY...THEN LIFTS
NE THROUGH THE TENNESSEE VALLEY AND INTO THE MID-ATLANTIC STATES
BY MONDAY. THIS STORM SHOULD PASS FAR ENOUGH SOUTH AND EAST OF THE
REGION TO PREVENT ANY SIGNIFICANT PCPN DEVELOPMENT OVER C/NE WI.
HOWEVER...LOW-LEVEL CYCLONIC FLOW AND THE PRESENCE OF THE BROAD
UPPER TROF COULD BRING SCT LIGHT SNOW SHOWERS OR FLURRIES AT
TIMES. FOR NOW...WILL MAINLY BE CARRYING SLIGHT CHC POPS FROM THE
LATE WEEKEND THROUGH MIDWEEK.
H8 TEMPS WILL NOT VARY MUCH OVER THE PERIOD...WITH MOST OF THE
MEDIUM RANGE MODELS FORECASTING -8 TO -12 C. THIS SHOULD CONTINUE
THE TREND OF BELOW NORMAL TEMPERATURES FOR THE NEXT WEEK...WITH
LOWS IN THE TEENS AND LOWER 20S...AND HIGHS IN THE 30S.
&&
.AVIATION...BKN TO OVC MVFR DECK TO DEVELOP ACROSS MUCH OF CENTRAL
AND NORTH-CENTRAL WISCONSIN EARLY THIS AFTERNOON. SKY CONDITIONS TO
TURN BKN AND OVC OVER NE WISCONSIN AS WELL...BUT ONLY SLIGHTLY
HIGHER THAN MVFR. BEST CHANCE OF SNOW SHOWERS TO OCCUR MID
AFTERNOON TO EARLY THIS EVENING...AND SOME POTENTIAL THAT VSBYS
COULD DROP TO IFR IN THE SNOW SHOWERS. NNW WINDS TO KEEP LAKE
EFFECT SNOW SHOWERS WITHIN THE SNOW BELTS OF N-C WISCONSIN TONIGHT
WHERE A FEW INCHES OF ACCUMULATION IS POSSIBLE. SKIES TO PARTIALLY
CLEAR EVERYWHERE ELSE. CLOUDS WILL THEN REDEVELOP BY LATE TOMORROW
MORNING ACROSS THE REGION.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/KIECKBUSCH
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
233 PM CDT WED MAR 20 2013
.SHORT TERM...TONIGHT AND THURSDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A BROAD AND
ELONGATED UPPER LEVEL LOW PRESSURE SYSTEM SPINNING FROM THE CENTRAL
GREAT LAKES TO NEW ENGLAND EARLY THIS AFTERNOON. CLOUDS HAVE BEEN
SPREADING SOUTH ACROSS THE UPPER PENINSULA AND NORTHERN WISCONSIN SO
FAR TODAY...AS A RESULT OF SHORTWAVE LOBES ROTATING AROUND THE
PARENT VORTEX...AND ALSO STEEPENING LOW LEVEL LAPSE RATES. THESE
CONDITIONS ALSO PROMOTE CONDITIONS FOR SIGNIFICANT LAKE EFFECT
SNOWS...WHICH ARE OCCURRING WITHIN THE SNOW BELTS OF THE WESTERN
UPPER PENINSULA. IN FACT...IRONWOOD HAS OSCILLATED BETWEEN 1/2SM
AND 3/4SM FOR MUCH OF THE DAY. LAKE EFFECT POTENTIAL IS THE MAIN
FORECAST CONCERN OVER THE NEXT 24 HOURS AS WIND TRAJECTORIES BECOME
MORE FAVORABLE FOR N-C WISCONSIN.
TONIGHT...SHORTWAVE TROUGH WILL DIVE SOUTH ACROSS CENTRAL AND
SOUTHERN WISCONSIN THIS EVENING...ON THE WESTERN FLANK OF THE UPPER
LOW. NOT SOLD THAT PRECIP WILL TURN OFF AT SUNSET...THOUGH DIURNAL
INSTABILITY WILL BE LOST. WILL KEEP LIGHT SNOW SHOWERS AND FLURRIES
GOING FOR A GOOD CHUNK OF THE EVENING. BEHIND THE SHORTWAVE...LOW
LEVEL WINDS TURN TO THE NNW. WIND TRAJECTORIES LOOK REALLY GOOD FOR
A SOLID LAKE EFFECT EVENT FOR N-C WISCONSIN. THERMAL PROFILES ARE
ALSO IN THE OPTIMAL DENDRITIC GROWTH ZONE THROUGH THE NIGHT...AND
THERE IS SUFFICIENT MOISTURE IN THE 850-700MB LAYER AS WELL. ON THE
MINUS SIDE...SUBSIDENCE WILL BE INCREASING THROUGH THE NIGHT AND
LAKE INDUCED CAPE WILL GRADUALLY DIMINISH. THE LOCAL LAKE EFFECT
PARAMETER DOES SHOW A SLIGHT DIMINISHING TREND TONIGHT...BUT NOT
THAT SIGNIFICANT. A LIMITING FACTOR MAY BE THE 15 KT BL WINDS...IN
WHICH THE NORTHERN PART OF VILAS COUNTY GETS ADVISORY CRITERIA
SNOW...AND THE SOUTHERN HALF DOES NOT. SO THINK WILL GO WITHOUT AN
ADVISORY AND ISSUE AN SPS FOR THE COUNTY TONIGHT...AND WILL
HIGHLIGHT THAT SEVERAL INCHES OF SNOW ARE POSSIBLE ACROSS THE
NORTHERN PART OF THE COUNTY. PARTIAL CLEARING SHOULD OCCUR OUTSIDE
THE LAKE EFFECT BELT DURING THE OVERNIGHT HOURS...BUT DO NOT THINK
WILL SEE DECOUPLING. AS A RESULT...LOW TEMPS WILL BE COMPARABLE TO
LAST NIGHTS LOWS.
THURSDAY...LAKE EFFECT SNOW SHOWERS WILL CONTINUE OVER N-C WISCONSIN
THROUGH EARLY AFTERNOON...BUT SHOULD DIMINISH AS DRY AIR INVADES
FROM THE NORTH. ELSEWHERE...AFTER A MOSTLY CLEAR TO PARTLY CLOUDY
START TO THE DAY...CLOUDS SHOULD BE INCREASING BY LATE MORNING OR
EARLY AFTERNOON AS WILL STILL HAVE PLENTY OF LOW LEVEL MOISTURE AND
STEEP LOW LEVEL LAPSE RATES AROUND. INCREASED CLOUD COVER...BUT
KEPT THE SNOW CHANCES CONFINED TO THE SNOW BELT. HIGHS SEVERAL
DEGREES WARMER THAN TODAY WITH HIGHS MAINLY IN THE MID TO UPPER 20S.
.LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY...MAIN FCST
CONCERN IS TEMPERATURES.
A LARGE UPPER LEVEL LOW WILL RESIDE OVER EASTERN CANADA AND THE
EASTERN GREAT LAKES REGION EARLY IN THE PERIOD...BUT WILL SHIFT
EAST BY FRI/SAT...ALLOWING WEAK RIDGING TO DEVELOP OVER WI. A
LARGE CANADIAN SFC HIGH WILL RIDGE INTO THE WESTERN GREAT LAKES
DURING THIS PERIOD...BRINGING DRY...BUT CONTINUED COOL CONDITIONS.
WITH LOW-LEVEL WINDS TURNING NNE-NE...CONSIDERED THE POSSIBILITY
OF SOME LIGHT LAKE EFFECT SNOW SHOWERS OR FLURRIES IN EASTERN WI...
BUT WINDS ARE VERY LIGHT ON FRIDAY NIGHT...AND MOISTURE AND
INSTABILITY ARE NOT VERY FAVORABLE ON SATURDAY...SO KEPT A DRY
FCST INTACT.
THE UPPER PATTERN WILL TRANSITION BACK TO A BROAD UPPER TROF LATE
IN THE WEEKEND...AND CONTINUING THROUGH THE MIDDLE OF NEXT WEEK.
THE ONLY SIGNIFICANT STORM OF THE WEEK IS A LOW PRESSURE SYSTEM
WHICH MOVES THROUGH THE SOUTHERN PLAINS ON SATURDAY...THEN LIFTS
NE THROUGH THE TENNESSEE VALLEY AND INTO THE MID-ATLANTIC STATES
BY MONDAY. THIS STORM SHOULD PASS FAR ENOUGH SOUTH AND EAST OF THE
REGION TO PREVENT ANY SIGNIFICANT PCPN DEVELOPMENT OVER C/NE WI.
HOWEVER...LOW-LEVEL CYCLONIC FLOW AND THE PRESENCE OF THE BROAD
UPPER TROF COULD BRING SCT LIGHT SNOW SHOWERS OR FLURRIES AT
TIMES. FOR NOW...WILL MAINLY BE CARRYING SLIGHT CHC POPS FROM THE
LATE WEEKEND THROUGH MIDWEEK.
H8 TEMPS WILL NOT VARY MUCH OVER THE PERIOD...WITH MOST OF THE
MEDIUM RANGE MODELS FORECASTING -8 TO -12 C. THIS SHOULD CONTINUE
THE TREND OF BELOW NORMAL TEMPERATURES FOR THE NEXT WEEK...WITH
LOWS IN THE TEENS AND LOWER 20S...AND HIGHS IN THE 30S.
&&
.AVIATION...M000 TO 3000 FT CIGS AND A FEW SNOW FLURRIES NEAR THE
MICHIGAN BORDER WILL TRY TO MOVE SOUTH A LITTLE BUT MOST PLACES
WILL BE CLEAR TONIGHT. COLD AIR ALOFT WILL GENERATE MVFR CIGS AND
SNOW SHOWERS WEDNESDAY AS AN UPPER LEVEL LOW MOVES SOUTH TOWARDS
THE REGION.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/KIECKBUSCH
AREA FORECAST DISCUSSION
NWS TAUNTON MA
204 AM EDT FRI MAR 22 2013
.SYNOPSIS...
LOW PRESSURE MOVING SOUTHEAST OF NANTUCKET WILL BRING A PERIOD OF
ACCUMULATING SNOW TO THE SOUTHEAST NEW ENGLAND COAST TONIGHT.
OTHERWISE...MAINLY DRY BUT CHILLY WEATHER FOR LATE MARCH WILL
CONTINUE THROUGH MOST OF NEXT WEEK. WILL HAVE TO KEEP A CLOSE EYE
ON A MID ATLANTIC STORM FOR SUN NIGHT/MON. ODDS FAVOR THE BULK OF
THE STORM PASSING TO OUR SOUTH...BUT STILL A LOW PROBABILITY IT
TRENDS NORTH AND BRINGS MORE SNOW TO THE REGION.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
200 AM UPDATE...
HAS MENTIONED IN PREV AFD HAVE UPGRADED ADV TO A WARNING FOR
SOUTHERN BRISTOL AND PLYMOUTH COUNTIES. HEAVY BAND OF SNOW THAT
WAS SITUATED OVER THOSE COUNTIES HAS SHIFTED TO OVER COASTAL
PLYMOUTH AND THE CANAL. EXPECT SNOW FALL RATES OF 1-2" PER HOUR
AND VSBYS REDUCED TO BELOW ONE HALF OF A MILE. ROADS WILL BECOME
QUICKLY SNOW COVERED. AM CONSIDERING UPGRADING THE WARNING ACROSS
EASTERN PLYMOUTH AND BARNSTABLE COUNTIES. LATEST WEBCAMS SHOW
SNOW COVERED ROADS AND HVY SNOW FALL WITHIN THE BANDS. ALTHOUGH
HAVE NOT RECEIVED ANY REPORTS...WOULD NOT BE SURPRISED IF OVER 6
INCHES WILL BE REPORTED BY MORNING.
IRONICALLY THE GFS MODEL HAS BEEN HANDLING THIS MESOSCALE FEATURE
BETTER THAN THE HI-RES AND THE NAM. THE HRRR IS ALSO DOING FAIRLY
WELL. IN FACT THE NAM DOESNT EVEN HAVE QPF FOR SE MASS RIGHT NOW!
THE 00Z MODELS ARE STILL SHOWING A GOOD AMOUNT OF LIFT AND
MOISTURE WITHIN THE SNOWGROWTH ZONE INTO THE MORNING SO HAVE
EXTENDED THE HAZARDS. DO NOT SEE ANY LARGE FEATURES THAT WILL
PUSH THESE BANDS OUT OF THE AREA ANY TIME SOON. INTERESTING TO SEE
THAT 850MB VAD WIND PROFILES ARE SHOWING GOOD CONVERGENCE WHERE
THE BAND HAS SET UP. BANDS WILL CONTINUE TO MOVE IN A MORE NNE
DIRECTION TO FOLLOW THE MID-LEVEL FLOW.
EXPECT A SLOW MORNING COMMUTE TO AREAS WITHIN THE HAZARDS RIGHT
NOW. ALTHOUGH FORECASTING 4-8 INCHES...ISOLATED HIGHER AMOUNTS ARE
POSSIBLE. THIS IS THE STRUGGLE OF TRYING TO PINPOINT THE EXACT
LOCATION OF THE BANDING FEATURE.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
MID LEVEL TROUGH STAYS PRETTY WELL PUT OVER THE NORTHEASTERN U.S.
THROUGH FRIDAY. THIS...IN COMBINATION WITH THE SURFACE LOW IN THE
MARITIMES WILL ALLOW FOR SOME FLURRIES AND ISOLATED LIGHT SNOW
SHOWERS TO LINGER OVER THE CAPE AND ISLANDS AS WELL AS START UP
ACROSS THE NORTHWESTERN ZONES LATER IN THE AFTERNOON. THESE SHOULD
START TO COME TO AN END OVERNIGHT AS THE MID LEVEL LOW AND SURFACE
LOW LIFT TO THE NORTHEAST TAKING THE LIFT AND MOISTURE WITH IT.
TEMPERATURES WERE A BLEND OF BIAS CORRECTED MOS...WITH HIGH TEMPS
REACHING THE MID TO UPPER 30S TO LOW 40S AND LOW TEMPS IN THE 20S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
HIGHLIGHTS...
* UNSEASONABLY CHILLY WEATHER THROUGH NEXT WEEK
* NEED TO KEEP A CLOSE EYE ON A MID ATLANTIC STORM SUN NIGHT/MON
DETAILS...
THE OVERALL PATTERN WILL CONTINUE TO FEATURE A NEGATIVE AO/NAO WELL
INTO NEXT WEEK. THIS WILL RESULT IN LOWER THAN AVERAGE HEIGHT
FIELDS AND IN TURN BELOW NORMAL TEMPS IN OUR REGION. MUCH OF THE
PERIOD WILL FEATURE DRY NORTHWEST FLOW...SO THE STRONG MARCH SUN
SHOULD STILL BE ENOUGH TO PUSH HIGHS INTO THE UPPER 30S TO MIDDLE
40S MUCH OF THE TIME. THE LATEST MEX GUIDANCE APPEARS TOO MILD
THOUGH AS IT OFTEN TRENDS MORE TOWARDS CLIMATOLOGY IN THE LATER PERIODS.
THE MAIN THING TO WATCH IS THE TRACK OF A MID ATLANTIC STORM SUNDAY
NIGHT INTO MONDAY. MOST OF THE GUIDANCE HAS BEEN IN GOOD AGREEMENT
THAT THE MAIN AFFECTS FROM THIS STORM WILL PASS SOUTH OF OUR REGION.
THIS A RESULT OF VERY STRONG HIGH LATITUDE BLOCKING AND THE CLOSED
UPPER LEVEL LOW NEAR THE CANADIAN MARITIMES. HOWEVER...THIS STORM IS
STILL ABOUT 4 DAYS AWAY AND IT WOULDN/T TAKE MUCH OF A NORTHWARD
ADJUSTMENT TO GET US INTO AT LEAST SOME OF THE PRECIPITATION SHIELD.
IF THIS WERE TO OCCUR...MOST OF THE REGION WOULD BE COLD ENOUGH FOR
A SNOW EVENT. SO WHILE ODDS CURRENTLY FAVOR MORE OF A MISS/GLANCING
BLOW TO THE SOUTH...THERE REMAINS A LOW PROBABILITY FOR ACCUMULATING
SNOW SUNDAY NIGHT INTO MONDAY. LOW POPS WERE INCLUDED IN THE
FORECAST TO ACCOUNT FOR THIS POSSIBILITY.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW...MODERATE CONFIDENCE EARLY THIS MORNING AND HIGH
CONFIDENCE AFTERWARDS.
MVFR TO IFR CONDITIONS ARE EXPECTED IN BANDS OF MODERATE TO HEAVY
SNOW SHOWERS ACROSS SOUTHEAST MA EARLY THIS MORNING. EXPECT
IMPROVING CONDITIONS BY THE MID-MORNING HOURS. VFR CONDITIONS
WILL PERSIST ELSEWHERE. DIURNAL CU WILL DEVELOP TOMORROW AS NW
WINDS MAY GUST TO 20-25 KTS BY THE AFTERNOON...LASTING THROUGH
THE OVERNIGHT HOURS.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SATURDAY AND SUNDAY...HIGH CONFIDENCE IN MAINLY VFR CONDITIONS.
NORTHWEST WIND GUSTS OF 25 TO 35 KNOTS EXPECTING DURING THE DAY
SAT...BUT MUCH LESS WIND ON SUN.
SUNDAY NIGHT AND MONDAY...LOW CONFIDENCE. MVFR-IFR CONDITIONS IN
SNOW WOULD OCCUR ONLY IF STORM ENDS UP TRACKING FURTHER NORTH THAN
CURRENT MODELS INDICATE.
TUESDAY...MODERATE TO HIGH CONFIDENCE. MAINLY VFR CONDITIONS.
&&
.MARINE...
MODERATE TO HIGH CONFIDENCE THROUGH FRIDAY NIGHT.
SEAS BUILD WITH THE PASSAGE OF A SURFACE LOW PRESSURE SOUTH AND EAST
OF THE COASTAL WATERS. 5 TO 6 FOOT SEAS ARE EXPECTED ON THE OUTER
WATERS BY FRIDAY MORNING AND 6 TO 8 FOOT SEAS BY FRIDAY NIGHT.
NORTHEASTERLY WINDS WILL SHIFT TO THE WEST AS THEY INCREASE TO
AROUND 25 KTS. SMALL CRAFT ADVISORIES ARE UP FOR THE SOUTHEASTERN
OUTER WATERS THROUGH FRIDAY AFTERNOON. THESE WILL LIKELY NEED TO BE
EXTENDED INTO FRIDAY NIGHT FOR MORE OF THE WATERS.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SATURDAY AND SATURDAY NIGHT...HIGH CONFIDENCE IN STRONG SCA WIND
GUSTS FROM THE NORTHWEST IN THE COLD AIR ADVECTION PATTERN. LOW
PROBABILITY FOR A PERIOD OF MARGINAL GALE FORCE WIND GUSTS.
SUNDAY...MODERATE TO HIGH CONFIDENCE. WINDS AND SEAS
SUBSIDING...BUT LINGERING SCA LIKELY NEEDED FOR AT LEAST THE MORNING.
SUNDAY NIGHT AND MONDAY...MODERATE CONFIDENCE. SHOULD SEE AT LEAST
SCA NORTHEAST WIND GUSTS DEVELOP LATE SUN NIGHT/MON AS LOW PRESSURE
PASSES SOUTH OF THE WATERS. THERE IS A LOW PROBABILITY FOR A PERIOD
OF GALE FORCE WIND GUSTS IF THE STORM TRACK ENDS UP FURTHER NORTH
THAN CURRENT MODELS INDICATE.
TUESDAY...MODERATE CONFIDENCE. MARGINAL NORTHWEST SCA WIND GUSTS OF
20 TO 25 KNOTS ARE POSSIBLE IN THE COLD AIR ADVECTION PATTERN BEHIND
THE DEPARTING LOW PRESSURE SYSTEM.
&&
.CLIMATE...
NORMAL HIGH TEMP/NORMAL LOW TEMP
BOS 47 / 32
BDL 50 / 29
PVD 49 / 31
ORH 45 / 28
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...WINTER WEATHER ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
MAZ018-019-022-023.
WINTER STORM WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR
MAZ020-021.
NH...NONE.
RI...WINTER WEATHER ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
RIZ007.
MARINE...SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 8 PM EDT THIS
EVENING FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
ANZ254>256.
&&
$$
SYNOPSIS...FRANK/RLG
NEAR TERM...DUNTEN
SHORT TERM...RLG
LONG TERM...FRANK
AVIATION...FRANK/DUNTEN
MARINE...FRANK/RLG
CLIMATE...STAFF
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
431 AM CDT FRI MAR 22 2013
...UPDATED LONG TERM SECTION...
.SYNOPSIS...
ISSUED AT 252 AM CDT FRI MAR 22 2013
THE BULK OF THE POLAR JET ENERGY WAS POSITIONED ACROSS THE SOUTHERN
ROCKIES, THROUGH THE SOUTHERN PLAINS, WRAPPING THROUGH THE SOUTHEAST
UNITED STATES JUST SOUTH OF THE NORTHEAST U.S. BROAD CLOSED LOW. A
SECOND SIGNIFICANT UPPER JET WAS DIVING SOUTHWARD ON THE HEELS OF
THE FIRST, INTO THE NORTHWEST PACIFIC REGION COASTLINE. THE MID
LEVELS EXHIBITES COLD 500 MB AIR TEMPERATURES BELOW -20 DEGREES
ACROSS MOST OF THE CONUS. THE AIR ASSOCIATED WITH THE 500 MB TROUGH
ACROSS THE NORTHWEST U.S. WAS -30 TO NEAR -40 DEGREES C. A STRONG
TEMPERATURE GRADIENT REMAINED IN PLACE FROM CENTRAL KANSAS, WHICH
MARKED THE EDGE OF THE FREEZING AT AT THE 850 MB LEVEL...TO THE
TEXAS PANHANDLE WHERE WARM +20 DEGREE C AIR WAS IN PLACE. RAIN AND
SNOW WERE FALLING ACROSS NORTHWEST KANSAS INTO SOUTH CENTRAL
NEBRASKA, ASSOCIATED WITH A STRONG BAROCLINIC ZONE AND ISENTROPIC
LIFT.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 252 AM CDT FRI MAR 22 2013
NUMEROUS SNOW SHOWERS CONTINUE TO DRIFT FROM WEST CENTRAL INTO
CENTRAL KANSAS THIS MORNING. THE HIGHEST CONCENTRATION OF SNOW
SHOWERS WILL MOVE THROUGH THE RUSH CENTER TO STAFFORD AND SAINT JOHNS
AREAS THOUGH 5 AM. AREAS TO THE SOUTH WILL FIND THE SHOWERS REALIZED
AS EITHER RAIN OR SNOW PRECIPITATION TYPE, AS WARMER TEMPERATURES
ARE FOUND NEAR THE OKLAHOMA LINE. BASED ON THE RAPID REFRESH THE
PRECIPITATION SHOULD CLEAR THE AREA BY 11 UTC. HOWEVER, LOW LEVEL
STRATUS WILL PERSIST THROUGH THE MORNING UNTIL THE STRONG MARCH SUN
CAN WARM THE BOUNDARY LAYER SUFFICIENTLY TO INDUCE MIXING. THE
LATEST NAM MODEL SUGGESTS THIS SHOULD OCCUR RAPIDLY BETWEEN 15 AND
18 UTC. AS A RESULT, DRY AIR IN WESTERN KANSAS WILL ALLOW RAPID
WARMING INTO THE 60S BY THE AFTERNOON, WHILE CENTRAL KANSAS COUNTIES
FROM HAYS TO PRATT AND MEDICINE LODGE WILL BE SLOWER TO RESPOND.
WEAK EASTERLY UPSLOPE WINDS SHOULD PERSIST THROUGH THE DAY, BEFORE
TURNING SLIGHTLY MORE SOUTHEASTERLY FOR A FEW HOURS IN RESPONSE TO
SURFACE CYCLOGENESIS OVER EASTERN COLORADO THROUGH THE EVENING AND
INTO TONIGHT.
WITH THE COOL STABLE BOUNDARY LAYER AIRMASS ACROSS CENTRAL KANSAS IN
PLACE, RAPID STRATUS REDEVELOPMENT SHOULD OCCUR AGAIN BEFORE
MIDNIGHT. MODEL CONSENSUS INDICATES WARM ADVECTION PRECIPITATION
CONVECTIVE SHOWERS ARE POSSIBLE THIS EVENING ACROSS THE FAR
SOUTHWEST KANSAS COUNTIES, ASSOCIATED WITH THE NEXT SYNOPTIC SCALE
STORM. CHANCES ARE GOOD THAT THE INITIAL SHOWERS WILL BECOME MORE
NUMEROUS THROUGH THE OVERNIGHT HOURS, AND LIKELY QUICKLY CAUSE
SURFACE TEMPERATURES ACROSS WESTERN KANSAS TO DROP TO THE WET BULB
TEMPERATURE CAUSING A PHASE CHANGE TO SNOW OVERNIGHT. AN INCH OR TWO
OF SNOW COULD BE POSSIBLE ACROSS ANY AREAS OF WEST CENTRAL KANSAS
THROUGH THE INTERSTATE 70 CORRIDOR BY 12Z SATURDAY.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 429 AM CDT FRI MAR 22 2013
WINTER STORM STILL THE FOCUS OF THE LONG TERM SECTION...WITH IMPACTS
THE MAIN CHALLENGE...IN TERMS OF TIMING AND SEVERITY...AND WHO WILL
GET THE BRUNT OF THE STORM.
400MB POTENTIAL VORTICITY (PV) STREAM EVIDENT ON RAP ANALYSIS AND
WATER VAPOR LOOP THIS MORNING FROM SOUTHWESTER BRITISH COLUMBIA TO
SOUTHWESTERN IDAHO. THIS STREAM OF HIGH PV AIR WILL AID IN THE
FORMATION OF A MID LEVEL CYCLONE BY EARLY SATURDAY OVER WESTERN
COLORADO. THE INCREASED UPPER TROPOSPHERIC JET STREAK DYNAMICS
ASSOCIATED WITH THE STORM WILL AID IN LOW LEVEL CYCLOGENESIS AS WELL
BY EARLY SATURDAY MORNING. SATURATION WILL OCCUR IN THE LOW LEVELS
WITH INITIAL PRECIPITATION BREAKING OUT LATE IN THE FRIDAY NIGHT
PERIOD INTO EARLY SATURDAY AS WARM, MOIST FRONTOGENESIS INCREASES
DRAMATICALLY IN THE 800-700MB LAYER. AS THE LOWER-MID TROPOSPHERIC
COLUMN SATURATES EARLY SATURDAY...THE VERTICAL THERMODYNAMIC PROFILE
WILL QUICKLY SUPPORT SNOW AS THE PROFILE GOES BELOW ZERO DEGC OVER
MUCH OF SOUTHWEST KANSAS...ESPECIALLY BY 18Z SATURDAY. THE SNOW WILL
INITIALLY BE A VERY WET SNOW AS SURFACE TEMPERATURES WILL BE IN THE
32 TO 35 DEGREE RANGE WITH A PREDOMINANTLY EAST TO EAST-NORTHEAST
SURFACE WIND THROUGH MIDDAY. BY AFTERNOON...SURFACE TEMPERATURES
WILL APPROACH 30 AND LOW LEVEL COLD ADVECTION WILL INCREASE WHICH
WILL ENHANCE THE DROP IN TEMPERATURE...ESPECIALLY WEST OF HIGHWAY
83. THE WINDS WEST OF HIGHWAY 83 WILL BECOME NORTH AND INCREASE TO
25 TO 30 MPH. THERE IS SOME CONCERN THAT GIVEN THE MAGNITUDE OF WIND
AND POTENTIAL ONE HALF TO ONE-INCH PER HOUR SNOWFALL RATES BY LATE
IN THE DAY...THAT WHITE-OUT OR NEAR WHITE-OUT CONDITIONS WILL OCCUR.
THE SNOW WILL BECOME INCREASINGLY SUSCEPTIBLE TO BLOWING AS
TEMPERATURES FALL INTO THE UPPER 20S BY 00Z AS FAR EAST AS HIGHWAY
283 (WAKEENEY TO DODGE CITY TO ASHLAND LINE). TEMPERATURE AND TIME
OF DAY WILL HAVE A HUGE IMPACT ON THE BLOWING AND DRIFTING OF
SNOW...LEADING TO THE NEAR-BLIZZARD OR EVEN BLIZZARD THREAT. IF THE
BRUNT OF THE STORM WAS TO OCCUR DURING THE MIDDLE OF THE DAY WITH
SURFACE TEMPERATURES IN THE 32 TO 34 DEGREE RANGE...THE THREAT FOR
BLOWING SNOW WOULD BE GREATLY REDUCED DUE TO THE VERY WET NATURE AND
COMPOSITION OF SNOW (LARGE, WET AGGREGATE FLAKES VS. DRIER
INDIVIDUAL DENDRITES). THE DENDRITIC GROWTH ZONE (-12C TO -16C) WILL
BE IN THE FAVORED 750-650MB LAYER DURING THE 00-09Z TIME FRAME
SUNDAY IN THE MID LEVEL DEFORMATION ZONE WHICH WILL AID IN SLIGHTLY
HIGHER SNOWFALL RATIO THAN WHAT WOULD TYPICALLY BE EXPECTED FOR LATE
MARCH...SO THIS IS SOMETHING TO KEEP IN MIND AS WELL.
GIVEN ALL OF THE ABOVE MENTIONED...AND WITH THE MID LEVEL
FRONTOGENETIC ZONE LIKELY JUST FAR ENOUGH SOUTH TO IMPACT THE
SOUTHERN COUNTIES (USING THE ECMWF AND CANADIAN GEM MORE SOUTHERN
SCENARIO)...WILL ISSUE A WINTER WEATHER ADVISORY IN THE SOUTHERN
COUNTIES NOT CURRENTLY IN THE WINTER STORM WATCH (ROUGHLY ARKANSAS
RIVER SOUTH TO THE OKLAHOMA BORDER). AS FAR AS STORM TOTAL SNOWFALL
AMOUNTS GO...THIS IS STILL A VERY DIFFICULT FORECAST AND WILL LIKELY
COME DOWN TO THE MESOSCALE COMPONENTS OF THE STORM ITSELF (AS IS
TYPICALLY THE CASE). THAT BEING SAID...IT STILL LOOKS LIKE THE
NORTHERN HALF OF THE FORECAST AREA (ARKANSAS RIVER TO INTERSTATE 700
WILL SEE TOTAL SNOWFALL IN THE 4 TO 7 INCH RANGE WITH A FEW 8 INCH
AMOUNTS POSSIBLE IN SOME SPOTS. FROM THE ARKANSAS RIVER SOUTH TO THE
OKLAHOMA BORDER...3 TO 5 INCHES IS THE FORECAST.
THE STORM WILL QUICKLY EXIT EAST SUNDAY MORNING WITH SOME REMNANT
LIGHT BLOWING AND DRIFTING THROUGH THE MORNING HOURS AFTER SUNRISE
SUNDAY. THE MARCH SUN WILL AID IN SNOWMELT ON ROAD SURFACES...BUT IT
WILL HAVE SOME WORK TO DO AS STRONG COLD ADVECTION WILL CONTINUE
THROUGH THE DAY AND 2-METER TEMPERATURES WILL STAY IN THE 20S MOST
OF THE DAY.
UNFORTUNATELY...HAVE HAD NO TIME TO ADDRESS THE FORECAST BEYOND
SUNDAY AND RUNNING WITH THE LATEST ALLBLEND GUIDANCE WHICH CALLS FOR
A SLOW WARM-UP MONDAY AND TUESDAY (30S AND 40S). BY WEDNESDAY...WE
SHOULD SEE A FAIRLY DRAMATIC WARM-UP BACK INTO THE 50S AND PERHAPS
60S. AFTER THIS BRIEF WARM-UP BACK TO CLIMO...WE WILL MOST LIKELY
ENTER ANOTHER COLD SPELL GOING INTO THE DAY 7-10 TIME FRAME AS WE
END THE MONTH OF MARCH.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 110 AM CDT FRI MAR 22 2013
RAPIDLY DEVELOPING STRATUS WILL LIKELY SOON BECOME WIDESPREAD
ACROSS MOST OF CENTRAL AND SOUTHWEST KANSAS. PERIODS OF RAIN/SNOW
SHOWERS ARE LIKELY AT KHYS THROUGH AROUND 10Z AS AN UPPER LEVEL
SHORTWAVE LIFTS THROUGH THE REGION. AS THE PRECIPITATION CLEARS BY
12Z AND STRONG INSOLATION DIMINISHES THE STRATUS, VFR CONDITIONS
ARE EXPECTED THROUGH EARLY FRIDAY EVENING WHEN THE EFFECTS OF THE
NEXT SYNOPTIC SCALE STORM BEGIN TO DEVELOP AS SCATTERED SHOWERS
AND DEVELOPING STRATUS ONCE AGAIN.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 52 35 35 23 / 10 80 90 90
GCK 52 33 33 21 / 10 90 90 90
EHA 56 37 37 21 / 20 90 90 80
LBL 56 38 38 23 / 10 80 90 80
HYS 48 30 31 23 / 10 90 90 90
P28 52 36 38 28 / 10 50 90 80
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
KSZ030-031-043>046-061>066.
WINTER WEATHER ADVISORY FROM 10 AM SATURDAY TO 7 AM CDT SUNDAY
FOR KSZ074>081-084>090.
&&
$$
SYNOPSIS...RUSSELL
SHORT TERM...RUSSELL
LONG TERM...UMSCHEID
AVIATION...RUSSELL
AREA FORECAST DISCUSSION
NWS WICHITA KS
342 AM CDT FRI MAR 22 2013
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 341 AM CDT FRI MAR 22 2013
FORECAST HIGHLIGHTS FOCUS AROUND FREEZING DRIZZLE CHANCES THIS
MORNING...WITH POTENTIALLY HEAVY SNOW SATURDAY-SATURDAY NIGHT.
A FAST MOVING SHORTWAVE APPROACHING FROM THE WEST IN CONCERT WITH A
SUBTLE 850-700MB TROUGH/CONVERGENCE ZONE AND SATURATED LOW-LEVELS IS
RESULTING IN PATCHY LIGHT FREEZING DRIZZLE EARLY THIS MORNING OVER
GENERALLY THE NORTHEAST 1/4 OF KS. GIVEN LATEST OBSERVATIONS AND
SHORT-TERM GUIDANCE...ANTICIPATE THIS ACTIVITY WILL AFFECT FAR
NORTHEAST/EAST PORTIONS OF THE FORECAST AREA EARLY THIS
MORNING...GENERALLY EAST/NORTHEAST OF A LINE EXTENDING FROM
SALINA-HILLSBORO-EUREKA-CHANUTE. GIVEN RELATIVELY WARM PAVEMENT
TEMPERATURES...NOT ANTICIPATING WIDESPREAD PROBLEMS ON
ROADS...ALTHOUGH BRIDGE DECKS AND OTHER ELEVATED SURFACES MAY BE
SLICK. NOT ANTICIPATING ISSUING A WINTER WEATHER ADVISORY.
ADDITIONALLY...PATCHY LIGHT SNOW WILL AFFECT PRIMARILY
CENTRAL/EAST-CENTRAL KS THROUGH EARLY TO MID MORNING...ASSOCIATED
WITH SATURATED MID-LEVELS AHEAD OF APPROACHING SHORTWAVE. SNOW
ACCUMULATIONS WILL LIKELY REMAIN WELL UNDER ONE-HALF INCH.
FURTHERMORE...LOOSELY ORGANIZED BAND OF SHOWERS/THUNDERSTORMS OVER
NORTHERN OK...ASSOCIATED WITH 850-700MB WARM/MOIST ADVECTION...WILL
LIKELY REMAIN SOUTH OF THE KS/OK BORDER AS ACTIVITY SHIFTS EAST
EARLY THIS MORNING.
ATTENTION THEN TURNS TO POTENTIAL WINTER STORM TO AFFECT THE REGION
SATURDAY-SATURDAY NIGHT...AS A SHORTWAVE CURRENTLY OVER THE PACIFIC
NORTHWEST DIVES SOUTHEAST AND STRENGTHENS. DESPITE SOME MINOR TO
MODEST DIFFERENCES IN TRACK AND INTENSITY...MODELS HAVE BEEN
TRENDING INTO BETTER AGREEMENT. IF THERE IS AN OUTLIER...IT`S THE
SLIGHTLY FASTER AND NOT QUITE AS AMPLIFIED GFS SOLUTION...WITH ALL
OTHER MODELS A TAD SLOWER AND DEEPER. MODEL CONSENSUS STILL
BULLSEYES CENTRAL/EAST-CENTRAL KS WITH THE GREATEST ACCUMULATIONS.
GIVEN EXPECTED STRONG FRONTOGENESIS...COUPLED FORCING AND DECENT
SNOW GROWTH ZONE LAPSE RATES...EXPECTING 4-7 INCHES GENERALLY NORTH
OF HIGHWAY 50. FURTHER SOUTH ACROSS SOUTH-CENTRAL/SOUTHEAST KS...A
RAIN/SNOW MIX WILL CUT INTO SNOW AMOUNTS...WITH ACCUMULATIONS OF 1-4
INCHES...LEAST NEAR THE KS/OK BORDER. OTHER THAN PATCHY POCKETS OF
SLEET...PREDOMINANT PRECIPITATION TYPES WILL LIKELY EITHER BE RAIN
OR SNOW GIVEN EXPECTED THERMAL PROFILES.
IT SHOULD BE SAID THERE DOES REMAIN SOME UNCERTAINTY...NAMELY THE
NAM SOLUTION...WHICH WOULD SUGGEST A SWATCH OF HEAVIER SNOW ALONG
THE TURNPIKE AND JUST SOUTHEAST SATURDAY NIGHT. GIVEN ITS TENDENCY
FOR EMBELLISHMENT BEYOND 36 HOURS...WILL NOT BITE JUST YET.
HEADLINES-WISE...WILL EXPAND WINTER STORM WATCH A BIT FURTHER EAST
TO INCLUDE HARVEY-MARION-CHASE COUNTIES. GIVEN LATEST 00Z ECMWF NOT
TRENDING SOUTH...WILL NOT EXPAND WATCH INTO SOUTHERN KS.
ALSO...GIVEN STILL SOME WOBBLE IN THE STORM`S TRACK AND
INTENSITY...WILL LET THE DAY SHIFT MAKE THE CALL ON WINTER STORM
WARNINGS AND ADVISORIES. SNOW SHOULD COME TO AN END SOMETIME LATE
SATURDAY NIGHT OR SUNDAY MORNING OVER EASTERN KS.
ADK
.LONG TERM...(MONDAY THROUGH THURSDAY NIGHT)
ISSUED AT 341 CDT FRI MAR 22 2013
A COLD EARLY TO MID WEEK IS ANTICIPATED...AS LONGWAVE TROUGHING
PERSISTS ACROSS THE CENTRAL AND EASTERN CONUS. GFS/ECMWF CONSENSUS
SUGGESTS BUILDING HEIGHTS/THICKNESS BY MID TO LATE WEEK...WHICH
SHOULD ALLOW TEMPERATURES TO AT LEAST CLIMB INTO THE 50S...WHICH
WOULD GET THEM CLOSER TO NORMAL IN THE 50S-60S.
ADK
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1145 PM CDT THU MAR 21 2013
AVIATION CONCERNS REMAIN LOW CIGS ALONG WITH SOME FREEZING DRIZZLE
POTENTIAL TONIGHT INTO FRI MORNING.
MVFR CIGS CONTINUE TO WORK WEST AND ARE JUST ABOUT READY TO GET
INTO KRSL. CURRENT THINKING IS THAT THESE CIGS WILL CONTINUE TO
LOWER OVERNIGHT WITH WIDESPREAD IFR CIGS LIKELY AFTER 08Z. THE
DRIZZLE THAT HAS OCCURRED SO FAR OVER NORTHEAST KS AND NW MO IS IN
AN AREA OF LOW LEVEL ISENTROPIC LIFT ALONG THE 285K SURFACE. IN FACT
THE LATEST RUC ANALYSIS IS SHOWING A COLD POCKET ALONG THIS SURFACE
RIGHT OVER FAR NORTHEAST KS WHICH IS LIKELY CONTRIBUTING TO THE
FREEZING DRIZZLE. AT THIS TIME FEEL THAT LOCATIONS NORTHEAST OF A
MCPHERSON TO EL DORADO TO CHANUTE LINE WILL HAVE THE BEST CHANCE TO
GET IN ON SOME OF THIS FREEZING DRIZZLE GENERALLY AFTER 10Z.
THEREFORE KCNU IS THE TAF SITE WITH THE BEST CHANCE TO SEE SOME OF
THIS EARLY FRI MORNING. BY AROUND 15-16Z CIGS WILL START TO CLIMB
ABOVE IFR LEVELS FOR LOCATIONS ALONG AND WEST OF I-135 WHILE KCNU
STAYS SOCKED-IN INTO THE AFTERNOON HOURS.
LAWSON
&&
.FIRE WEATHER...
ISSUED AT 341 AM CDT FRI MAR 22 2013
BELOW NORMAL TEMPERATURES THROUGH AT LEAST EARLY TO MID NEXT WEEK
ALONG WITH THE POTENTIAL FOR WIDESPREAD PRECIPITATION SATURDAY AND
SATURDAY NIGHT SHOULD CREATE RELATIVELY LOW FIRE DANGER OVER THE
NEXT SEVERAL DAYS.
ADK
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 51 34 37 28 / 10 40 60 80
HUTCHINSON 50 32 36 27 / 10 50 70 80
NEWTON 49 32 34 26 / 10 40 70 80
ELDORADO 48 33 37 28 / 20 30 60 80
WINFIELD-KWLD 51 35 40 29 / 10 30 60 80
RUSSELL 49 31 33 23 / 10 50 90 90
GREAT BEND 52 31 34 24 / 0 50 80 90
SALINA 48 31 35 27 / 20 40 80 90
MCPHERSON 49 32 34 26 / 10 40 80 90
COFFEYVILLE 47 35 44 31 / 20 20 60 80
CHANUTE 43 33 41 29 / 30 10 60 80
IOLA 42 32 41 28 / 30 10 60 80
PARSONS-KPPF 46 35 43 30 / 20 10 60 80
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY
AFTERNOON FOR KSZ032-033-047>053-067-068.
&&
$$
AREA FORECAST DISCUSSION
NWS WICHITA KS
1145 PM CDT THU MAR 21 2013
.UPDATE...
ISSUED AT 1015 PM CDT THU MAR 21 2013
UPDATED TO MAKE SOME MINOR TWEAKS TO GRIDS.
WATER VAPOR IMAGERY CONTINUES TO SHOW THE UPPER WAVE SLIDING OVER
WEST-CENTRAL KS. MEANWHILE EAST SURFACE WINDS CONTINUE TO ADVECT
HIGHER LOW LEVEL MOISTURE AND LOW CIGS ACROSS THE AREA. LOW LEVEL
ISENTROPIC LIFT IS RESULTING IN SOME DRIZZLE OVER NORTHEAST KS AND
WESTERN MISSOURI. WOULD EXPECTED THIS AREA OF DRIZZLE TO EVENTUALLY
EXPAND OVER SE PORTIONS OF THE FORECAST AREA. THE CHALLENGE TONIGHT
WILL BE KEEPING AN EYE ON SURFACE TEMPS FOR POSSIBLE FREEZING
DRIZZLE. THEY SHOULD HOVER VERY CLOSE TO OR JUST ABOVE FREEZING WITH
A POSSIBLE DECREASE AS SITES START TO WET BULB DOWN SLIGHTLY. THE
PRECIP OVER NW KS SHOULD ALSO IMPACT THE AREA AFTER 06Z AND MAY
BRING A MIX OF SOME SNOW OR LIGHT RAIN.
WHILE CONFIDENCE IS NOT HIGH ENOUGH AT THIS POINT TO RUN WITH AN
ADVISORY FOR FREEZING DRIZZLE...WOULD NOT BE SURPRISED TO SEE A
SMALL SHORT-LIVED ONE OUT FOR THE MORNING COMMUTE.
LAWSON
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 330 PM CDT THU MAR 21 2013
TONIGHT-FRI: LOTS OF DRY AIR IN THE LOWEST 2-3K FEET OF THE
ATMOSPHERE HAS LIMITED PRECIP REACHING THE GROUND TO THE EXTREME
ERN HALF OF THE FORECAST AREA. BUT MID LEVEL LIFT HAS BEEN SLOW TO
MOVE INTO THE AREA...WITH LOWER LAYER LIFT INCREASING INTO THE
EVENING HOURS ACROSS MAINLY ACROSS SRN/SERN KS. AS THIS LIFT
INCREASES...WILL SEE THE LOWER LAYERS SATURATE ENOUGH FOR AT LEAST
A DRIZZLE CHANCE ACROSS CENTRAL AND SRN KS. SFC TEMPS CLOSE TO
FREEZING ALONG OR NORTH OF HIGHWAY 50 MAY LEAD TO SOME VERY LIGHT
FREEZING DRIZZLE. FURTHER TO THE NORTH ALONG I-70 COULD SEE SOME
LIGHT RAIN OR SLEET MIX IN WITH THE FREEZING DRIZZLE AS WELL. SO
WILL CONTINUE THIS MENTION OVERNIGHT. NOT THINKING THIS WINTRY MIX
WILL LEAD TO ANY TRAVEL PROBLEMS AS WARM GROUND TEMPS WILL LEAD TO
FREEZING ONLY ON ELEVATED SURFACES.
AFTER THIS INITIAL LIFT MOVES EAST...LOW LEVEL MOISTURE WILL REMAIN
SOMEWHAT HIGH INTO FRI FOR SOME LOW CLOUDS. BUT FRI WILL BE THE
LULL BETWEEN THIS EVENINGS SYSTEM AND A MUCH MORE SIGNIFICANT SYSTEM
FOR SAT. SO ACTUALLY COULD SEE SOME BREAKS IN THE CLOUDS ON
FRI...WITH SUNSHINE ACTUALLY WARMING MAX TEMPS IN THE 50S FOR MOST
AREAS WEST OF INTERSTATE 135.
SAT-SUN: MODELS ARE COMING TOGETHER ON A MORE SIGNIFICANT STORM
SYSTEM EXPECTED TO MOVE OUT OF THE ROCKIES INTO THE PLAINS ON SAT.
THIS SYSTEM WILL START OUT WITH BETTER LOW LEVEL MOISTURE THAN
TODAYS SYSTEM...WITH WARM ADVECTION AND MOISTURE TRANSPORT AHEAD
OF THIS SHORTWAVE LEADING TO AN INCREASING CHANCE OF WIDESPREAD
SNOW OVER MOST OF CEN KS ON SAT. SATURATION/LIFT INCREASES IN THE
MAIN SNOW GROWTH REGION BY AROUND NOON SAT ACROSS CEN KS. SFC
TEMPS MAY START OUT JUST A LITTLE ABOVE FREEZING IN CEN
KS...BEFORE WET BULB EFFECTS DROP TEMPS ENOUGH FOR A HEAVY WET
SNOW TO BEGIN ACCUMULATING BY LATE SAT AFTN. THIS LIFT AND
SATURATION LASTS THE LONGEST OVER MOST OF CEN KS...FOR MODERATE
SNOW ACCUMULATIONS BY SAT EVE...WITH SOME AREAS IN CEN KS HAVING
THE POTENTIAL TO SEE 4 TO 7 INCHES OF ACCUMULATION. STRONG GUSTY
N-NW WINDS WILL ALSO BEGIN TO RAMP UP AS WELL FOR SAT
AFTN/EVE...SO WITH POSSIBLE TRAVEL IMPACTS ACROSS CEN KS...WILL
HOIST A WINTER STORM WATCH FOR CEN KS. A LITTLE MORE UNCERTAIN ON
HOW FAR SOUTH TO TAKE THIS WATCH...AS A MIX OF RAIN/SNOW WILL
CHANGEOVER TO ALL SNOW ACROSS SOUTH CEN KS AS WELL FOR SAT EVE.
THINK INITIAL SNOWFALL MAY MELT AS IT FALLS WHICH WILL CUT DOWN ON
SNOW TOTALS FOR AREAS NEAR KICT/EL DORADO AND NEWTON. COULD STILL
SEE ACCUMULATIONS AROUND 3 INCHES IN THIS AREA AS WELL...AS BEST
COMBINATION OF LIFT/SATURATION MOVES ACROSS SOUTH CEN KS BETWEEN
00-06Z/SUN. WOULD NOT BE SURPRISED TO SEE CEN KS UPGRADED TO A
WARNING WITH LATER SHIFTS WITH A POSSIBLE ADVISORY FOR AREAS
BETWEEN HIGHWAY 50 AND 54.
KETCHAM
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 327 PM CDT THU MAR 21 2013
AFTER THE WEEKEND SYSTEM MOVES OUT OF THE AREA...A BROAD TROUGH
LOOKS TO REMAIN OVER THE NORTHERN PLAIN FOR MON INTO TUE...WITH A
CANADIAN HIGH PRESSURE AREA SETTLING OVER THE AREA. THIS WILL LEAD
TO TEMPS REMAINING WELL BELOW NORMAL FOR THE START OF THE
WEEK...WITH BOTH THE GFS/ECMWF SHOWING 850H TEMPS OF MINUS 10. SO
EXPECT TEMPS TO STRUGGLE ACROSS THE AREA FOR MON/TUE...WITH TEMPS
EXPECTED TO BE 15 TO 20 DEGREES BELOW NORMAL. EXPECT A SLOW
WARMING TREND TOWARDS WED/THU WHICH WILL LEAD TO TEMPS CLOSER TO
CLIMO NORMS..WITH DRY CONDITIONS EXPECTED.
KETCHAM
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1145 PM CDT THU MAR 21 2013
AVIATION CONCERNS REMAIN LOW CIGS ALONG WITH SOME FREEZING DRIZZLE
POTENTIAL TONIGHT INTO FRI MORNING.
MVFR CIGS CONTINUE TO WORK WEST AND ARE JUST ABOUT READY TO GET
INTO KRSL. CURRENT THINKING IS THAT THESE CIGS WILL CONTINUE TO
LOWER OVERNIGHT WITH WIDESPREAD IFR CIGS LIKELY AFTER 08Z. THE
DRIZZLE THAT HAS OCCURRED SO FAR OVER NORTHEAST KS AND NW MO IS IN
AN AREA OF LOW LEVEL ISENTROPIC LIFT ALONG THE 285K SURFACE. IN FACT
THE LATEST RUC ANALYSIS IS SHOWING A COLD POCKET ALONG THIS SURFACE
RIGHT OVER FAR NORTHEAST KS WHICH IS LIKELY CONTRIBUTING TO THE
FREEZING DRIZZLE. AT THIS TIME FEEL THAT LOCATIONS NORTHEAST OF A
MCPHERSON TO EL DORADO TO CHANUTE LINE WILL HAVE THE BEST CHANCE TO
GET IN ON SOME OF THIS FREEZING DRIZZLE GENERALLY AFTER 10Z.
THEREFORE KCNU IS THE TAF SITE WITH THE BEST CHANCE TO SEE SOME OF
THIS EARLY FRI MORNING. BY AROUND 15-16Z CIGS WILL START TO CLIMB
ABOVE IFR LEVELS FOR LOCATIONS ALONG AND WEST OF I-135 WHILE KCNU
STAYS SOCKED-IN INTO THE AFTERNOON HOURS.
LAWSON
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 33 50 36 39 / 30 10 30 60
HUTCHINSON 31 52 34 36 / 30 10 30 70
NEWTON 29 48 34 35 / 30 10 30 60
ELDORADO 30 49 36 39 / 40 20 20 60
WINFIELD-KWLD 33 54 37 42 / 40 10 20 60
RUSSELL 29 51 31 33 / 30 10 50 80
GREAT BEND 31 54 33 34 / 30 10 50 80
SALINA 30 51 32 36 / 30 20 30 70
MCPHERSON 31 50 33 35 / 30 10 30 70
COFFEYVILLE 33 50 37 45 / 50 20 20 60
CHANUTE 30 48 35 41 / 50 20 20 60
IOLA 29 45 34 39 / 50 30 10 60
PARSONS-KPPF 31 48 37 44 / 50 20 20 60
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY
AFTERNOON FOR KSZ032-033-047>051-067.
&&
$$
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1139 PM CDT THU MAR 21 2013
.UPDATE...
ISSUED AT 1136 PM CDT THU MAR 21 2013
UPDATED AVIATION SECTION FOR 06Z TAF ISSUANCE.
UPDATE ISSUED AT 850 PM CDT THU MAR 21 2013
FORECAST APPEARS TO BE ON TRACK...WITH NO CHANGES MADE TO SNOWFALL
AMOUNTS OR ADVISORY AREAS. A BUFFER ZONE OF CHANCE POPS WAS EXPANDED
A COUPLE OF COUNTIES TO THE EAST FOR TONIGHT...MAINLY ALONG A KMDH
TO KPAH TO KHOP LINE. THIS WAS BASED MAINLY ON RUC MODEL DATA. THE
21Z RUC WAS MORE AGGRESSIVE THAN PREVIOUS RUNS IN BRINGING THE DEEP
MOISTURE /AS INDICATED BY 1000 TO 500 MB MEAN RH/ EASTWARD. RADAR
TRENDS SUPPORT THE RUC MODEL. WHATEVER PRECIP MAKES IT INTO THE AREA
OF CHANCE POPS WILL BE INSIGNIFICANT...SINCE THE MODELS DECREASE THE
DEEP MOISTURE FROM NORTHWEST TO SOUTHEAST LATE TONIGHT.
ALSO...SURFACE TEMPS WILL BE AT OR ABOVE FREEZING MUCH OF THE NIGHT
WHERE PRECIP OCCURS.
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 259 PM CDT THU MAR 21 2013
NO CHANGES PLANNED TO THE WINTER WEATHER ADVISORY.
THE 12Z MODELS ARE IN AGREEMENT WITH THE SYNOPTIC-SCALE
FEATURES/EVOLUTION THROUGH FRIDAY NIGHT. THE REGION WILL BE
SANDWICHED UNDER A WEAK UPPER RIDGE THAT SEPARATES A LARGE UPPER
LOW OVER QUEBEC FROM A DIGGING TROUGH OVER THE NORTHERN ROCKIES.
A COUPLE OF RELATIVELY WEAK MID-LEVEL DISTURBANCES WILL TRY TO
PUSH THROUGH THE SKINNY RIDGE AND ACROSS OUR AREA TONIGHT AND
FRIDAY. AS THE WESTERN TROUGH DIGS INTO THE CENTRAL ROCKIES...THE
MID/UPPER RIDGE ASSERTS ITSELF OVER OUR REGION FRIDAY NIGHT.
ALTHOUGH THE NAM AND GFS EACH PRODUCE PLENTY OF CLOUD COVER
TONIGHT AND INTO FRIDAY MORNING OVER THE SOUTHWEST THIRD OF THE
AREA...SIGNIFICANT FOCUSED LIFT IS HARDER TO COME BY. THE TWO
MODELS ARE IN AGREEMENT IN SOME FOCUSED LIFT AROUND 00Z OVER
RIPLEY COUNTY. THE LIFT IS MAXIMIZED IN THE DENDRITIC GROWTH ZONE
WHICH COULD LEAD TO QUITE AN INITIAL BURST OF ACCUMULATING SNOW.
THE PROBLEM IS THAT THE LIFT DOES NOT LAST LONG AT ALL...AND
FOCUSED/SIGNIFICANT LIFT IS HARD TO FIND LATE THIS EVENING AND
OVERNIGHT. WOULD NOT BE BE SURPRISED IF THE ADVISORY IS CANCELLED
EARLY. ON TOP OF THE LIFT ISSUE...THE SNOW WILL HAVE TO OVERCOME
A VERY COLD...DRY AIRMASS FOR LATE MARCH. THIS WILL LIKELY RESULT
IN A VERY SHARP NORTHEAST EDGE TO THE ACCUMULATING SNOW. WILL
LEAVE THE ADVISORY AREA ALONE DUE TO COUNTY GEOMETRY ISSUES...BUT
NORTHEASTERN PORTIONS OF STODDARD AND NEW MADRID AND MAYBE EVEN
WAYNE COUNTY MAY STRUGGLE TO GET AN INCH OF SNOW TONIGHT.
USED HPC QPF AND A 10 TO 1 SNOW TO LIQUID RATIO TO GET VERY SIMILAR
STORM TOTAL SNOW ACCUMULATIONS AS PREVIOUSLY FORECAST. 4 INCHES
WILL BE A REAL POSSIBILITY IN SOUTHWEST PORTIONS OF RIPLEY COUNTY
WITH A SHARP GRADIENT DOWN TO AN INCH FROM GREENVILLE TO DEXTER TO
NEW MADRID.
MODEL SOUNDINGS INDICATE THAT THE COLUMN WILL APPROACH THE
FREEZING LINE IN THE FAR SOUTHWEST LATE THIS EVENING...WHICH WOULD
LEAD TO SOME SLEET POTENTIAL. THIS COULD POTENTIALLY LEAD TO
LOWER ACCUMULATIONS. THE MODELS ARE IN AGREEMENT IN WARMING THE
COLUMN QUICKLY FRIDAY MORNING...SO ANY PRECIPITATION THAT IS LEFT
WILL TRANSITION TO RAIN BY MIDDAY. ANY PRECIPITATION WILL BE FOCUSED
ON THE SOUTHERN BORDER OF THE AREA FRIDAY...BUT WOULD BE SURPRISED
TO SEE MUCH AT ALL. FRIDAY NIGHT SHOULD BE DRY...BUT LEFT A 20-30
POP OVER THE SOUTHERN HALF OF THE AREA JUST TO FIT IN.
IT SHOULD BE QUITE COLD IN THE NORTHEAST TONIGHT...GUIDANCE SEEMS
TO HAVE THIS IN HAND. UNDERCUT GUIDANCE FOR HIGHS FRIDAY IN MOST
LOCATIONS WITH PLENTY OF CLOUDS AND AN EAST WIND EXPECTED. KNOCKED
LOWS FRIDAY NIGHT DOWN QUITE A BIT WITH GOOD RADIATIONAL COOLING
EXPECTED. GUIDANCE HAS A GOOD IDEA FOR FRIDAY NIGHT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 259 PM CDT THU MAR 21 2013
THE GENERAL WEATHER SCENARIO FOR THE WEEKEND AND INTO EARLY NEXT
WEEK HAS STABILIZED SOMEWHAT WITH RESPECT TO THE PROMINENT FEATURES
IMPACTING THE WFO PAH FORECAST AREA.
THE MANDATORY LEVEL TEMPERATURES FROM SURFACE TO 700 MB FOR THE 00Z
AND 12Z THURSDAY NUMERICAL MODEL SUITES INITIALIZED ONE HALF TO
ALMOST TWO DEGREES TOO WARM UPSTREAM AND OVER THE WFO PAH FORECAST
AREA. THE LEAST IMPACTED GUIDANCE HAS BEEN THE DETERMINISTIC NAM-WRF
SUITE...FOLLOWED BY THE SREF/GFS GUIDANCE...THE ECMWF AND CANADIAN
GUIDANCE...FOLLOWED BY THE GFS ENSEMBLE /WHICH IRONICALLY WAS ONE OF
THE BETTER PERFORMING MODELS ON WEDNESDAY/.
WITH RESPECT TO A POP/WEATHER/WEATHER TYPE SOLUTION FOR THE EXTENDED
FORECAST PERIOD...THIS MEANS ESSENTIAL TRACK OF THE NORTH-SOUTH
ORIENTED TROUGH IN THE LEE OF THE CENTRAL ROCKIES WILL DIG INTO A
SURFACE LOW SLIGHTLY FURTHER SOUTH. THE MAIN TRACK OF THE SURFACE
LOW WILL LIKELY BE JUST SOUTH OF THE WFO PAH FORECAST
AREA...POSSIBLY NUDGING INTO SOUTHEAST SECTIONS OF THE PENNYRILE
REGION OF WEST KENTUCKY...NEAR /KHOP/ FORT CAMPBELL KY. BOTH THE
UPPER LOW AND SURFACE LOW WILL MOVE IN CONCERT AND DEEPEN RAPIDLY
/BECOME MORE VERTICALLY STACKED OVER THE SOUTHERN HALF OF THE WFO
PAH FORECAST AREA GENERALLY BETWEEN /10 PM CDT/ SATURDAY NIGHT TO /7
AM CDT/ SUNDAY MORNING.
THE BIG QUESTIONS FOR SATURDAY NIGHT INTO SUNDAY MORNING WILL BE
MULTI-FOLD. THE FIRST QUESTION IS TO WHAT DEGREE OF THE VERTICAL
MOMENTUM /UPWARD MOTION/ WILL BE TRANSLATED INTO HORIZONTAL FORCING
ON THE NORTHERN/SOUTHERN ENDS OF THE WFO PAH FORECAST AREA...MAINLY
IN SURFACE WIND AND TEMPERATURE FIELDS FOR SHARPENING GRADIENTS.
MOST OF THE MODEL GUIDANCE IS SUGGESTING THAT A GOOD PORTION OF THE
ENERGY WILL BE EXPENDED VERTICALLY. THIS NOTION CONTINUES TO SUPPORT
A MENTION OF THUNDERSTORMS ALONG THE SOUTHERN COUNTIES OF THE WFO
PAH FORECAST AREA...WHERE LAPSE RATES/VORTICITY/FORCING WILL SUPPORT
UPRIGHT CONVECTION ALONG AND JUST NORTH OF THE SURFACE LOW. THE
SECOND QUESTION WILL BE WHETHER THE TRANSIENT DEFORMATION ZONE ALONG
ROUTE 60 IN SOUTHEAST MO...ROUTE 13 IN SOUTHERN IL AND THE OHIO
RIVER IN SOUTHWEST IN/NORTHWEST KY...WILL CAUSE A SIGNIFICANT PHASE
CHANGE IN PRECIPITATION TYPE. IT IS CONCEIVABLE THAT THERE MAY BE A
1 TO 3 HOUR PERIOD OVERNIGHT IN THE AFOREMENTIONED AREA WHERE
MID-LEVEL FORCING MAY GENERATE UPRIGHT CONVECTION /THUNDERSTORMS/
AND MIXED PRECIPITATION /SLEET...HAIL...SNOW...RAIN/ NEAR THE
DEFORMATION ZONE. ALSO...GIVEN THE DEMARCATION LINE BETWEEN
MEASURABLE SNOW ALONG THE NORTHERN EDGE OF THE WFO PAH FORECAST
AREA...WOULD PREFER TO SEE THE OUTPUT FROM THE 4KM NAM-WRF GUIDANCE
ON FRIDAY BEFORE PINPOINT PRECIPITATION TYPE...INTENSITY AND THE
OCCURRENCE OF THUNDERSTORMS ALONG THE NORTH END OF THE WFO PAH
FORECAST AREA. THE STORM PREDICTION CENTER HAS ALREADY HINTED IN
THEIR DAY THREE OUTLOOK A CHANCE FOR GENERAL THUNDER ACROSS MOST OF
THE WFO PAH FORECAST AREA. PLAN TO ADD A CONDITIONAL MENTION OF
THUNDER ACROSS THE NORTHERN EDGE OF THE WFO PAH FORECAST AREA FOR
PLANNING PURPOSES...ALTHOUGH THERE WILL BE NO MENTION OF
THUNDERSTORMS IN THE NORTH WITH THIS FORECAST PACKAGE.
FOLLOWING THE PASSAGE OF THE SURFACE/UPPER LOW SATURDAY NIGHT INTO
SUNDAY...THE NUMERICAL MODELS HAVE SPED UP THE DEPARTURE OF
MEASURABLE POPS/WEATHER FROM SOUTHWEST TO NORTHEAST BY AS MUCH AS
SIX HOURS OR MORE. THIS SHOULD DRY THINGS OUT ACROSS THE WFO PAH
FORECAST AREA FROM TUESDAY THROUGH WEDNESDAY. ANOTHER...WEAKER
IMPULSE IS FORECAST TO MOVE THROUGH ON THURSDAY...BUT SHOULD
CONTRIBUTE LITTLE TO ANY MEASURABLE PRECIPITATION.
AS MENTIONED NEAR THE TOP OF THE EXTENDED FORECAST
DISCUSSION...TEMPERATURES WERE TOO WARM. ADJUSTMENTS WERE MADE TO
KEEP TEMPERATURES SOME 15 TO 25 DEGREES BELOW NORMAL AS THE FLOW
AROUND THE SEMI-PERMANENT EASTERN U.S. CYCLONIC VORTEX KEEPS
THICKNESSES LOWER AND SUSTAIN COLD AIR ADVECTION ACROSS THE WFO PAH
FORECAST AREA. WOULD NOT BE SURPRISED TO SEE MULTIPLE DAYS OF COLD
AIR STRATOCUMULUS OR STRATUS...ESPECIALLY ALONG THE NORTHERN 1/2 OF
THE WFO PAH FORECAST AREA. A FEW FLURRIES OR SPRINKLES MAY BE
LIKELY...BUT DO NOT PLAN TO MENTION THESE TRACE EVENTS SO FAR OUT IN
THE FORECAST PACKAGE BASED ON POTENTIAL COVERAGE.
THERE MAY BE SOME LIGHT AT THE END OF THE COLD TEMPERATURE
TUNNEL...AS THE 240 HOUR GUIDANCE SHOWS A STRONG RIDGE NOSING INTO
WESTERN MO...IT MAY TAKE UNTIL THE FIRST WEEK OF APRIL BEFORE WE SEE
ANY MEASURABLE WARMING AT OR ABOVE NORMAL /LOW TO MID 60S/ THIS TIME
OF YEAR.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 259 PM CDT THU MAR 21 2013
NO CHANGES PLANNED TO THE WINTER WEATHER ADVISORY.
THE 12Z MODELS ARE IN AGREEMENT WITH THE SYNOPTIC-SCALE
FEATURES/EVOLUTION THROUGH FRIDAY NIGHT. THE REGION WILL BE
SANDWICHED UNDER A WEAK UPPER RIDGE THAT SEPARATES A LARGE UPPER
LOW OVER QUEBEC FROM A DIGGING TROUGH OVER THE NORTHERN ROCKIES.
A COUPLE OF RELATIVELY WEAK MID-LEVEL DISTURBANCES WILL TRY TO
PUSH THROUGH THE SKINNY RIDGE AND ACROSS OUR AREA TONIGHT AND
FRIDAY. AS THE WESTERN TROUGH DIGS INTO THE CENTRAL ROCKIES...THE
MID/UPPER RIDGE ASSERTS ITSELF OVER OUR REGION FRIDAY NIGHT.
ALTHOUGH THE NAM AND GFS EACH PRODUCE PLENTY OF CLOUD COVER
TONIGHT AND INTO FRIDAY MORNING OVER THE SOUTHWEST THIRD OF THE
AREA...SIGNIFICANT FOCUSED LIFT IS HARDER TO COME BY. THE TWO
MODELS ARE IN AGREEMENT IN SOME FOCUSED LIFT AROUND 00Z OVER
RIPLEY COUNTY. THE LIFT IS MAXIMIZED IN THE DENDRITIC GROWTH ZONE
WHICH COULD LEAD TO QUITE AN INITIAL BURST OF ACCUMULATING SNOW.
THE PROBLEM IS THAT THE LIFT DOES NOT LAST LONG AT ALL...AND
FOCUSED/SIGNIFICANT LIFT IS HARD TO FIND LATE THIS EVENING AND
OVERNIGHT. WOULD NOT BE BE SURPRISED IF THE ADVISORY IS CANCELLED
EARLY. ON TOP OF THE LIFT ISSUE...THE SNOW WILL HAVE TO OVERCOME
A VERY COLD...DRY AIRMASS FOR LATE MARCH. THIS WILL LIKELY RESULT
IN A VERY SHARP NORTHEAST EDGE TO THE ACCUMULATING SNOW. WILL
LEAVE THE ADVISORY AREA ALONE DUE TO COUNTY GEOMETRY ISSUES...BUT
NORTHEASTERN PORTIONS OF STODDARD AND NEW MADRID AND MAYBE EVEN
WAYNE COUNTY MAY STRUGGLE TO GET AN INCH OF SNOW TONIGHT.
USED HPC QPF AND A 10 TO 1 SNOW TO LIQUID RATIO TO GET VERY SIMILAR
STORM TOTAL SNOW ACCUMULATIONS AS PREVIOUSLY FORECAST. 4 INCHES
WILL BE A REAL POSSIBILITY IN SOUTHWEST PORTIONS OF RIPLEY COUNTY
WITH A SHARP GRADIENT DOWN TO AN INCH FROM GREENVILLE TO DEXTER TO
NEW MADRID.
MODEL SOUNDINGS INDICATE THAT THE COLUMN WILL APPROACH THE
FREEZING LINE IN THE FAR SOUTHWEST LATE THIS EVENING...WHICH WOULD
LEAD TO SOME SLEET POTENTIAL. THIS COULD POTENTIALLY LEAD TO
LOWER ACCUMULATIONS. THE MODELS ARE IN AGREEMENT IN WARMING THE
COLUMN QUICKLY FRIDAY MORNING...SO ANY PRECIPITATION THAT IS LEFT
WILL TRANSITION TO RAIN BY MIDDAY. ANY PRECIPITATION WILL BE FOCUSED
ON THE SOUTHERN BORDER OF THE AREA FRIDAY...BUT WOULD BE SURPRISED
TO SEE MUCH AT ALL. FRIDAY NIGHT SHOULD BE DRY...BUT LEFT A 20-30
POP OVER THE SOUTHERN HALF OF THE AREA JUST TO FIT IN.
IT SHOULD BE QUITE COLD IN THE NORTHEAST TONIGHT...GUIDANCE SEEMS
TO HAVE THIS IN HAND. UNDERCUT GUIDANCE FOR HIGHS FRIDAY IN MOST
LOCATIONS WITH PLENTY OF CLOUDS AND AN EAST WIND EXPECTED. KNOCKED
LOWS FRIDAY NIGHT DOWN QUITE A BIT WITH GOOD RADIATIONAL COOLING
EXPECTED. GUIDANCE HAS A GOOD IDEA FOR FRIDAY NIGHT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 259 PM CDT THU MAR 21 2013
THE GENERAL WEATHER SCENARIO FOR THE WEEKEND AND INTO EARLY NEXT
WEEK HAS STABILIZED SOMEWHAT WITH RESPECT TO THE PROMINENT FEATURES
IMPACTING THE WFO PAH FORECAST AREA.
THE MANDATORY LEVEL TEMPERATURES FROM SURFACE TO 700 MB FOR THE 00Z
AND 12Z THURSDAY NUMERICAL MODEL SUITES INITIALIZED ONE HALF TO
ALMOST TWO DEGREES TOO WARM UPSTREAM AND OVER THE WFO PAH FORECAST
AREA. THE LEAST IMPACTED GUIDANCE HAS BEEN THE DETERMINISTIC NAM-WRF
SUITE...FOLLOWED BY THE SREF/GFS GUIDANCE...THE ECMWF AND CANADIAN
GUIDANCE...FOLLOWED BY THE GFS ENSEMBLE /WHICH IRONICALLY WAS ONE OF
THE BETTER PERFORMING MODELS ON WEDNESDAY/.
WITH RESPECT TO A POP/WEATHER/WEATHER TYPE SOLUTION FOR THE EXTENDED
FORECAST PERIOD...THIS MEANS ESSENTIAL TRACK OF THE NORTH-SOUTH
ORIENTED TROUGH IN THE LEE OF THE CENTRAL ROCKIES WILL DIG INTO A
SURFACE LOW SLIGHTLY FURTHER SOUTH. THE MAIN TRACK OF THE SURFACE
LOW WILL LIKELY BE JUST SOUTH OF THE WFO PAH FORECAST
AREA...POSSIBLY NUDGING INTO SOUTHEAST SECTIONS OF THE PENNYRILE
REGION OF WEST KENTUCKY...NEAR /KHOP/ FORT CAMPBELL KY. BOTH THE
UPPER LOW AND SURFACE LOW WILL MOVE IN CONCERT AND DEEPEN RAPIDLY
/BECOME MORE VERTICALLY STACKED OVER THE SOUTHERN HALF OF THE WFO
PAH FORECAST AREA GENERALLY BETWEEN /10 PM CDT/ SATURDAY NIGHT TO /7
AM CDT/ SUNDAY MORNING.
THE BIG QUESTIONS FOR SATURDAY NIGHT INTO SUNDAY MORNING WILL BE
MULTI-FOLD. THE FIRST QUESTION IS TO WHAT DEGREE OF THE VERTICAL
MOMENTUM /UPWARD MOTION/ WILL BE TRANSLATED INTO HORIZONTAL FORCING
ON THE NORTHERN/SOUTHERN ENDS OF THE WFO PAH FORECAST AREA...MAINLY
IN SURFACE WIND AND TEMPERATURE FIELDS FOR SHARPENING GRADIENTS.
MOST OF THE MODEL GUIDANCE IS SUGGESTING THAT A GOOD PORTION OF THE
ENERGY WILL BE EXPENDED VERTICALLY. THIS NOTION CONTINUES TO SUPPORT
A MENTION OF THUNDERSTORMS ALONG THE SOUTHERN COUNTIES OF THE WFO
PAH FORECAST AREA...WHERE LAPSE RATES/VORTICITY/FORCING WILL SUPPORT
UPRIGHT CONVECTION ALONG AND JUST NORTH OF THE SURFACE LOW. THE
SECOND QUESTION WILL BE WHETHER THE TRANSIENT DEFORMATION ZONE ALONG
ROUTE 60 IN SOUTHEAST MO...ROUTE 13 IN SOUTHERN IL AND THE OHIO
RIVER IN SOUTHWEST IN/NORTHWEST KY...WILL CAUSE A SIGNIFICANT PHASE
CHANGE IN PRECIPITATION TYPE. IT IS CONCEIVABLE THAT THERE MAY BE A
1 TO 3 HOUR PERIOD OVERNIGHT IN THE AFOREMENTIONED AREA WHERE
MID-LEVEL FORCING MAY GENERATE UPRIGHT CONVECTION /THUNDERSTORMS/
AND MIXED PRECIPITATION /SLEET...HAIL...SNOW...RAIN/ NEAR THE
DEFORMATION ZONE. ALSO...GIVEN THE DEMARCATION LINE BETWEEN
MEASURABLE SNOW ALONG THE NORTHERN EDGE OF THE WFO PAH FORECAST
AREA...WOULD PREFER TO SEE THE OUTPUT FROM THE 4KM NAM-WRF GUIDANCE
ON FRIDAY BEFORE PINPOINT PRECIPITATION TYPE...INTENSITY AND THE
OCCURRENCE OF THUNDERSTORMS ALONG THE NORTH END OF THE WFO PAH
FORECAST AREA. THE STORM PREDICTION CENTER HAS ALREADY HINTED IN
THEIR DAY THREE OUTLOOK A CHANCE FOR GENERAL THUNDER ACROSS MOST OF
THE WFO PAH FORECAST AREA. PLAN TO ADD A CONDITIONAL MENTION OF
THUNDER ACROSS THE NORTHERN EDGE OF THE WFO PAH FORECAST AREA FOR
PLANNING PURPOSES...ALTHOUGH THERE WILL BE NO MENTION OF
THUNDERSTORMS IN THE NORTH WITH THIS FORECAST PACKAGE.
FOLLOWING THE PASSAGE OF THE SURFACE/UPPER LOW SATURDAY NIGHT INTO
SUNDAY...THE NUMERICAL MODELS HAVE SPED UP THE DEPARTURE OF
MEASURABLE POPS/WEATHER FROM SOUTHWEST TO NORTHEAST BY AS MUCH AS
SIX HOURS OR MORE. THIS SHOULD DRY THINGS OUT ACROSS THE WFO PAH
FORECAST AREA FROM TUESDAY THROUGH WEDNESDAY. ANOTHER...WEAKER
IMPULSE IS FORECAST TO MOVE THROUGH ON THURSDAY...BUT SHOULD
CONTRIBUTE LITTLE TO ANY MEASURABLE PRECIPITATION.
AS MENTIONED NEAR THE TOP OF THE EXTENDED FORECAST
DISCUSSION...TEMPERATURES WERE TOO WARM. ADJUSTMENTS WERE MADE TO
KEEP TEMPERATURES SOME 15 TO 25 DEGREES BELOW NORMAL AS THE FLOW
AROUND THE SEMI-PERMANENT EASTERN U.S. CYCLONIC VORTEX KEEPS
THICKNESSES LOWER AND SUSTAIN COLD AIR ADVECTION ACROSS THE WFO PAH
FORECAST AREA. WOULD NOT BE SURPRISED TO SEE MULTIPLE DAYS OF COLD
AIR STRATOCUMULUS OR STRATUS...ESPECIALLY ALONG THE NORTHERN 1/2 OF
THE WFO PAH FORECAST AREA. A FEW FLURRIES OR SPRINKLES MAY BE
LIKELY...BUT DO NOT PLAN TO MENTION THESE TRACE EVENTS SO FAR OUT IN
THE FORECAST PACKAGE BASED ON POTENTIAL COVERAGE.
THERE MAY BE SOME LIGHT AT THE END OF THE COLD TEMPERATURE
TUNNEL...AS THE 240 HOUR GUIDANCE SHOWS A STRONG RIDGE NOSING INTO
WESTERN MO...IT MAY TAKE UNTIL THE FIRST WEEK OF APRIL BEFORE WE SEE
ANY MEASURABLE WARMING AT OR ABOVE NORMAL /LOW TO MID 60S/ THIS TIME
OF YEAR.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1136 PM CDT THU MAR 21 2013
RADAR SHOWS SNOW SOUTH/WEST OF KCGI AND MODELS...FOR THE MOST
PART...KEEP IT THERE. LOW VFR CIGS SHOULD SEE A SCATTERED MVFR
DECK BECOME PREVAILING OVERNIGHT/TOWARD MORNING. THIS WILL
TRANSLATE TO PADUCAH AS WELL...AND THEN FURTHER EAST TO KEVV/KOWB
BY THE PLANNING PERIOD. TOWARD THE END OF THE EFFECTIVE VALID
TIME...SOME LIGHT PCPN MAY DEVELOP KCGI/KPAH.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...WINTER WEATHER ADVISORY UNTIL 7 AM CDT FRIDAY FOR MOZ100-107>110-
114.
IN...NONE.
KY...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DULUTH MN
259 AM CDT FRI MAR 22 2013
.SHORT TERM...THROUGH SATURDAY.
THE NORTHLAND WILL REMAIN BETWEEN UPPER TROUGHS TODAY...WITH
NARROW RIDGING...THEN WE WILL BECOME INCREASINGLY UNDER THE
INFLUENCE OF THE WESTERN TROUGH AS IT MOVES TOWARD THE REGION
TONIGHT INTO SATURDAY.
THE MAIN FOCUS TODAY WILL BE ON CLOUD COVER...AS LOW LEVEL
NORTHEASTERLY FLOW WAS ALREADY SPREADING CLOUDS INTO THE THE
ARROWHEAD AND THROUGH NORTHWEST ONTARIO. THE NAM...ECMWF AND THE
RAP...WERE DOING A DECENT JOB HANDLING THESE CLOUDS THIS MORNING.
THE ECMWF SUGGESTS THE CLOUDS WILL DIMINISH THIS AFTERNOON...THE
RAP HOLDS THEM IN TODAY AND SPREADS THEM WELL SOUTH INTO OUR CWA.
THE NAM IS A COMPROMISE. WE DO EXPECT SOME THINNING OF THOSE
CLOUDS THIS AFTERNOON...THE RAP WAS WAY OVERDONE YESTERDAY. WE
INCREASED SKY COVER OVER THE NORTHERN AND EASTERN CWA
TODAY...ESPECIALLY THIS MORNING. WE KEPT THE FORECAST DRY TODAY
INTO TONIGHT...BUT WOULD NOT BE SURPRISED IF SOME FLURRIES
DEVELOPED. OVERALL...WE EXPECT HIGHS TODAY FROM 29F TO 35F.
TONIGHT...WITH PERSISTENT LOW LEVEL NORTHEAST FLOW WE EXPECT THE
CLOUDS TO EXPAND WEST AND SOUTH THROUGH MUCH OF THE CWA AND HAVE
MOST AREAS MOSTLY CLOUDY TONIGHT INTO SATURDAY. THE CLOUDS SHOULD
HOLD TEMPS UP TONIGHT...AND WE HAVE THEM FROM 8F TO 14F. SOME
POCKETS OF COLDER TEMPS WILL BE POSSIBLE IN ANY AREAS THAT SEE AN
EXTENDED PERIOD OF MOSTLY CLEAR SKIES...SINCE WINDS WILL BE LIGHT.
A SHORTWAVE WILL ROTATE THROUGH THE AREA ON SATURDAY...AND SHOULD
BE ENOUGH TO SET OFF SOME FLURRIES. WE HAVE SCATTERED FLURRIES
MAINLY OVER OUR MINNESOTA ZONES...INTO FAR NORTHWEST WISCONSIN.
HIGHS SHOULD REBOUND TO 30F TO 35F FOR MOST AREAS.
.LONG TERM...SAT NIGHT THROUGH FRIDAY.
THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT
OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH
OVER THE ROCKIES THROUGH THE WEEKEND WITH A PERSISTENT NORTH TO
NORTHEAST BDRY LAYER FLOW. MODELS IN GOOD AGREEMENT THAT A VORT MAX
EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST ACROSS THE SRN
PLAINS THROUGH SUNDAY. MEANWHILE...LATEST MODEL RUNS ARE SUGGESTING A
SHORT WAVE BREAKS FREE FROM MAIN FLOW AND LIFTS INTO THE UPPER
PLAINS. THE 00Z RUNS OF THE ECM/NAM/GFS ALL SHOW THE SHORT WAVE
BECOMES A CLOSED H50 LOW IN THE VCNTY OF MONTANA/WRN DAKOTAS BY
SUNDAY MORNING. ATTM...HAVE KEPT FCST DRY THROUGH THE WEEKEND AS THE
FORCING/PRECIP FROM THE WAVE IN THE DAKOTAS LOOKS TO REMAIN TO THE
WEST OF THE FA...WHILE THE SOUTHERN STREAM LOW STAYS WELL OFF TO THE
SOUTH. HOWEVER...RH FIELDS AND LATEST NAM BUFR SOUNDINGS CONTINUE TO
SHOW INCREASING LOW LEVEL MOISTURE SAT NIGHT/SUN...SO HAVE
INTRODUCED BROADBRUSH FLURRIES DURING THIS TIME. THE ONSHORE WINDS
MAY ALLOW FOR ADDITIONAL LIFT/ENHANCEMENT TO PRODUCE A FEW LIGHT SNOW
SHOWERS ALONG SOUTH SHORE OF LAKE SUPERIOR SUNDAY THROUGH EARLY NEXT
WEEK.
BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS
MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST.
LATEST RUNS OF THE ECM/GEM/GFS ARE ALL SUGGESTING A H50 CLOSED LOW
RETROGRADES ACROSS HUDSON BAY AND TRACKS INTO MANITOBA THROUGH
MONDAY. FROM HERE THERE ARE LARGE MODEL DIFFERENCES IN THE TRACK OF
THE VORT MAX AS THE ECM KEEPS THE LOW NEARLY STATIONARY OVER
MANITOBA...WHILE THE GFS DROPS THE LOW ACROSS THE DLH CWA THROUGH
MID-WEEK.
&&
.AVIATION...
A STRATUS DECK WITH CEILINGS AROUND 2 KFT SEEN ON SATELLITE
IMAGERY OVER ONTARIO...WILL PUSH SOUTH AND WEST INTO THE FORECAST
AREA THROUGH DAYBREAK. THIS AREA OF LOW CLOUDS IS EXPECTED TO
MAINLY AFFECT THE THE KINL AND KHIB TERMINALS WHERE HAVE ADDED A
TEMPO FOR MVFR CIGS...THROUGH THE EARLY MORNING. ELSEWHERE...CLEAR
SKIES AND VFR CIGS WILL PREVAIL WITH A BRIEF PERIOD OF LOWER VSBYS
DUE TO LIGHT FG/BR POSSIBLE THROUGH 12Z.
&&
.POINT TEMPS/POPS...
DLH 31 15 32 17 / 10 10 10 10
INL 30 10 32 15 / 10 10 10 10
BRD 32 13 33 18 / 0 10 10 10
HYR 33 8 35 16 / 0 10 10 10
ASX 31 11 32 17 / 10 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...MELDE
LONG TERM....GRANING
AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS DULUTH MN
109 AM CDT FRI MAR 22 2013
.AVIATION...06Z TAF ISSUANCE...
CLOUDS LINGER OVER THE MN ARROWHEAD TOWARDS THE TWIN PORTS HOWEVER
CEILINGS REMAIN VFR FOR THE MAJORITY OF THE SITES. EXPECT VFR TO
PREVAIL THIS PERIOD ALTHOUGH A BRIEF PERIOD OF MVFR MAY DEVELOP OVER
NRN/ERN TERMINALS.
&&
PREV DISCUSSION... /ISSUED 308 PM CDT THU MAR 21 2013/
SHORT TERM.../NOW - FRIDAY/
AT 3PM/2000Z...THERE WAS A RIDGE OF HIGH PRESSURE OVER THE
NORTHERN PLAINS AND SOUTHERN MINNESOTA. THE NORTHLAND HAD LIGHT NW
WINDS DUE TO A LARGE LOW PRESSURE SYSTEM OVER THE NORTHEASTERN
UNITED STATES AND SOUTHEASTERN CANADA. MOST OF THE NORTHLAND HAD
SUNNY TO MOSTLY SUNNY SKIES...BUT THERE WAS STILL SOME LINGERING
LAKE EFFECT SNOW RELATED OVC CLOUDS OVER THE FAR EASTERN FORECAST
AREA IN NW WISCONSIN. THE OVC CLOUDS WERE QUICKLY DIMINISHING AS
THE WINDS WEAKENED OVER WESTERN LAKE SUPERIOR...CUTTING OFF THE
MOISTURE SUPPLY. TEMPERATURES WERE IN THE LOWER TO UPPER 20S
ACROSS THE NORTHLAND.
TONIGHT...THE HIGH PRESSURE IN THE NORTHERN PLAINS WILL SLOWLY
MOVE INTO THE NORTHLAND. THE NORTHLAND CAN EXPECT CLEAR TO MOSTLY
CLEAR SKIES. THERE COULD BE SOME CLOUDS OVER THE TIP OF THE
ARROWHEAD LATE TONIGHT. THE NAM AND RAP INDICATE SOME ENHANCED LOW
LEVEL MOISTURE MOVING INTO THAT AREA...BUT LEANED ON A CLEAR
FORECAST. THE MODEL GUIDANCE IS LIKELY MUCH TOO WARM CONSIDERING
THE CLEAR SKIES AND VERY LIGHT WINDS EXPECTED FOR TONIGHT...SO
UNDERCUT THE MODEL CONSENSUS BY SEVERAL DEGREES. OVERNIGHT LOWS
WILL PROBABLY BE WELL INTO THE SINGLE DIGITS BELOW ZERO ACROSS
MOST OF THE NORTHLAND.
FRIDAY...THE HIGH PRESSURE OVER THE NORTHLAND WILL PROMOTE SUNNY
TO MOSTLY SUNNY SKIES FOR AT LEAST THE MORNING. THERE COULD BE
SOME INCREASING CLOUD COVER IN THE AFTERNOON BASED ON MODEL RH.
HOWEVER...LEANED ON LESS CLOUD COVER SINCE THE MODELS SEEM TO BE
EXAGGERATING THE POTENTIAL FOR CLOUD COVER. FRIDAY COULD VERY
EASILY BE SUNNY ACROSS THE REGION...SO UPDATES MIGHT NEED TO BE
MADE IN THE FUTURE. HIGH TEMPERATURES WILL LIKELY BE IN THE LOWER
30S.
LONG TERM.../FRIDAY NIGHT - WEDNESDAY NIGHT/
CONTINUED QUIET WEATHER CONDITIONS THROUGH THE WEEKEND AND INTO
THE MIDDLE OF NEXT WEEK WITH A NARROW RIDGE OF HIGH PRESSURE
SITUATED OVER THE UPPER MIDWEST BETWEEN TWO SLOW MOVING UPPER
LOWS. THE LOW TO THE WEST WILL EVENTUALLY UNDERCUT THE HIGH
PRESSURE BY THIS WEEKEND. HOWEVER...THE ACTIVE PATTERN WILL REMAIN
WELL TO THE SOUTH AND LEAVE THE NORTHLAND MOSTLY DEVOID OF
PRECIPITATION. THE LOW LEVEL FLOW WILL BE FAVORABLE FOR A
PERSISTENT E/NE WIND OFF LAKE SUPERIOR AND KEEP MUCH OF THE
NORTHLAND UNDER THE INFLUENCE OF MOSTLY CLOUDY SKIES THROUGH THE
WEEK. THE LACK OF SUN...COMBINED WITH A RELATIVELY COLD AIR
MASS...850MB TEMPS -11 DEG C...WILL KEEP AFTERNOON HIGHS IN THE
LOWER 30S AND OVERNIGHT LOWS IN THE TEENS. ROUGHLY 5-10 DEG BELOW
AVERAGE. COULD SEE A FEW WEAK WAVES ROTATE WWD FROM THE UPPER
TROUGH OVER ERN CANADA EARLY NEXT WEEK...BUT ONLY A SLIGHT CHANCE
OF LIGHT SNOW IS POSSIBLE FROM THESE...WITH LITTLE TO NO SNOW
ACCUMULATING.
&&
.POINT TEMPS/POPS...
DLH 12 32 16 32 / 10 10 10 10
INL 9 31 16 32 / 10 10 10 10
BRD 12 33 19 33 / 0 10 10 10
HYR 8 34 16 34 / 0 10 0 10
ASX 11 32 16 33 / 0 0 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS BISMARCK ND
133 AM CDT FRI MAR 22 2013
.DISCUSSION...
MAIN UPDATES WERE TO ADJUST THE EASTWARD PROGRESSION OF THE SNOW
BAND...ADJUST SKY COVER BASED ON LATEST SAT IMAGERY...AND TO
ADJUST TEMPERATURES BASED ON LATEST OBSERVATIONS AND HR NEAR TERM
MODEL DATA. OVERALL...UPDATES WERE MINOR WITH THE INHERITED
FORECAST ON TRACK.
LATEST RADAR IMAGERY/SURFACE OBSERVATIONS CONTINUE TO
SHOW LIGHT SNOW BAND IN THE WEST WITH A SLIGHT MOVEMENT
EASTBOUND. THE RAP MAINTAINS A VERY SLOW PROGRESSION EAST THROUGH
FRIDAY AFTERNOON. WATER VAPOR IMAGERY SHOWS AN UPPER LOW BEGINNING
TO FORM OVER NORTH CENTRAL MONTANA WITH A SURFACE LOW BASICALLY
UNDERNEATH THE UPPER LOW FORMATION. THE SURFACE/UPPER AIR LOW IS
FORECAST TO MOVE TO NEAR BAKER MONTANA BY 12Z FRIDAY.
HENCE...EXPECT A CONTINUATION OF A FAIRLY SHARP DELINEATION FROM
SNOW TO NO SNOW. STILL LOOKS LIKE MID TO LATE MORNING FOR THE SNOW
TO ENTER THE BISMARCK AND MINOT AREAS.
&&
.AVIATION...
FOR THE 06Z FRIDAY TAF ISSUANCE...LIGHT SNOW WILL CONTINUE ACROSS
THE WESTERN AERODROMES OF KISN/KDIK WITH MVFR/IFR CIGS AND VSBYS
THROUGH FRIDAY AFTERNOON. LOW IFR/MVFR CIGS AT KBIS/KMOT ARE
EXPECTED TO DEVELOP BY AROUND 09Z FRIDAY...WITH LIGHT SNOW AND
MVFR VSBYS INITIATING BETWEEN 15Z AND 18Z FRIDAY. EXPECT SCT TO
BKN MVFR CIGS AND PATCHY FOG AT KJMS BY AROUND 09Z
FRIDAY...HOWEVER NO SNOWFALL OCCURRING UNTIL 22Z FRIDAY WITH MVFR
CIGS COMMENCING AT THAT TIME.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...NH
AVIATION...KS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
448 AM EDT FRI MAR 22 2013
.SYNOPSIS...
AN UPPER LEVEL LOW OVER THE CANADIAN MARITIMES WILL REMAIN
NEARLY STATIONARY INTO THE WEEKEND. A NEW STORM SYSTEM MOVING OUT
OF THE OF THE MID- MISSISSIPPI VALLEY LATER THIS WEEKEND COULD
BRING ANOTHER ROUND OF WINTRY PRECIPITATION TO THE REGION LATE
SUNDAY NIGHT AND MONDAY.
THE UNUSUAL BLOCKING PATTERN IN THE UPPER ATMOSPHERE IS EXPECTED
TO KEEP THE PERSISTENT CHILL IN THE AIR RIGHT THROUGH THE END OF
THE MONTH.
&&
.NEAR TERM /THROUGH TODAY/...
AT LEAST TWO LAKE EFFECT SNOW BANDS MANAGED TO MEANDER DOWN INTO
THE CENTRAL MOUNTAINS OVER THE LAST SEVERAL HOURS LEAVING A FRESH
COATING OF SNOW HERE AT THE OFFICE. OTHERWISE THE PATTERN HAS NOT
CHANGED SIGNIFICANTLY...WITH MINOR DISTURBANCES BEING CHANNELED DOWN
THE PERSISTENT COLD NW FLOW...OCCASIONALLY GIVING A POSITIVE BOOST
TO THE VERTICAL MOTIONS.
IT FINALLY LOOKS LIKE WE WILL SEE AT LEAST SOME MINOR IMPROVEMENT
TODAY AS HEIGHTS ALOFT BEGIN TO RISE...INVERSION HEIGHTS COME
DOWN AND LOW LEVEL WINDS BECOME MORE WESTERLY. HAVE NOT CHANGED
THE TIMING OF THE LAKE SNOW ADVISORY SINCE IT LOOKS GOOD FOR THE
SNOW SHOWERS TO BECOME LESS ORGANIZED AS WE GET DEEPER INTO THE
DAY.
TODAY`S HIGHS RANGING FROM THE MID 20S TO MID 40S FROM NW TO SE
WILL BE SOME 10 TO 20 DEG BELOW NORMAL AS THIS UNUSUAL EARLY SPRING
CHILL CONTINUES LOCKED IN OVER THE REGION.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM SATURDAY/...
ANY LINGERING SNOW SHOWERS OVER NWRN AREAS WILL TAPER TO FLURRIES
TONIGHT AS WE FINALLY START TO LOSE THE MOIST CYCLONIC FLOW ON THE
BACK SIDE OF THE CANADIAN LOW. SKIES WILL SCATTER OUT OVER MOST
OF THE FORECAST AREA...ALLOWING TEMPS TO FALL BACK INTO THE TEENS
AND 20S...STILL WELL BELOW NORMAL FOR LATE MARCH.
SATURDAY WILL REPRESENT A PERIOD OF BRIEF TRANQUILITY IN THE WAKE
OF THE SLOW MOVING LOW THAT HAS BEEN KEEPING US CLOUDY-COLD AND
UNSETTLED. HIGH PRESSURE WILL NOSE IN FROM THE LAKES WITH AT LEAST
SOME DRIER WEATHER...THOUGH IT WILL NOT BE SIGNIFICANTLY WARMER
THAN TODAY.
ANY LINGERING FLURRIES WILL REMAIN VERY NEAR AND DOWNWIND OF LAKE
ERIE.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
THE EXTENDED FORECAST WILL BE DOMINATED BY THE PROSPECTS OF YET
MORE LATE WINTER/EARLY SPRING WINTRY WEATHER.
MODELS ARE IN GOOD ACCORD WITH BRINGING A NEW TROF/UPPER LOW
SWINGING AROUND UNDER THE NORTHERN CANADIAN BLOCKING HIGH...AND
TRACKING IT EAST TOWARD THE MID ATLANTIC STATES. THE BIG QUESTIONS
CENTER ON HOW CLOSE THE PRIMARY AND SECONDARY STORMS MANAGE TO
GET TO THE LOCAL AREA AND HOW MUCH PRECIP THEY WILL PRODUCE.
THE 00Z NAM IS VERY AGGRESSIVE AND IMPLIES WE COULD SEE WIDESPREAD
SNOWS IN EXCESS OF 6 INCHES. THE GFS IS SLIGHTLY LESS AGGRESSIVE
BUT STILL IMPLIES WARNING SNOWS FOR MUCH OF CENTRAL AND SOUTHERN
PA. THE ECMWF IS MUCH DRIER...WITH ABOUT .25 TO LESS THAN .50"
QPF OVER THE SRN HALF OF THE FCST AREA.
THE SREF/GEFS BOTH SHOW A HIGH LIKELIHOOD OF AT LEAST .25"/12HR
QPF...WITH THE CHANCES FOR .50"/12HR RUNNING IN THE 50-70% RANGE.
MUCH BOTHERS ME ABOUT THE SREF/GEFS/NAM/GFS SCENARIOS.
TRADITIONALLY WE DO NOT DO REAL WELL FROM THESE MILLER TYPE B
REDEVELOPING LOWS UNLESS THE COASTAL LOW BECOMES THE BIG PRECIP
PLAYER LOCALLY. IT SEEMS THE OPERATIONAL MODELS WANT MOST OF OUR
PRECIP TO BE ASSOCIATED WITH THE DYING PRIMARY LOW AND I AM HARD
PRESSED TO RECALL AN EVENT WHERE WE GOT MORE THAN 6" OF SNOW FROM
SUCH A SET UP. IT SEEMS THE MOISTURE USUALLY RAPIDLY SHIFTS TO
THE COASTAL LOW AND WE GET HIT HARD ONLY IF THE COASTAL TRACKS
CLOSE ENOUGH...WHICH ALL BUT THE NAM ARE INDICATING WILL NOT
HAPPEN.
THE ENSEMBLES HAVE THE REQUISITE ANOMALOUS EASTERLY LOW LEVEL JET
WHICH IS A CHECK MARK ON THE FAVORABLE SIDE OF THE LEDGER...BUT
THE BEST PWATS NEVER GET ANYWHERE NEAR THE REGION...BEING RAPIDLY
PINCHED OFF AND SHUNTED WELL OUT INTO THE ATLANTIC.
OUR MOST RECENT STORM QPF WAS OFF BADLY...BY ABOUT HALF...PERHAPS
BY THE NORTHERN EDGE OF THE PRECIP BEING ROBBED OF MOISTURE BY
CONVECTION FURTHER SOUTH...AND I HAVE TO WONDER IF THIS WILL
HAPPEN AGAIN AS THE MODELS DO INDICATE INSTABILITY SURGING NORTH
TOWARD BOTH THE PRIMARY AND EXPECTED COASTAL LOWS.
AT THIS POINT WE HAVE SNOW/RAIN INDICATED FOR SUNDAY INTO
MONDAY...BUT CONFIDENCE IS VERY LOW AS TO QUANTITIES.
AFTER THE STORM GOES BY...WE ONCE AGAIN LOCK IN UNDER A DEEP NW
FLOW UNDER THE AMAZINGLY PERSISTENT NORTHERN CANADA/GREENLAND
UPPER BLOCKING HIGH. THE GEFS SHOWS THIS RIDGE TO STAY IN PLACE
THROUGH ABOUT MID WEEK WHEN IT FINALLY SHOWS SIGNS OF THE BLOCK
BEGINNING TO BREAK DOWN.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
A COLD NORTHWEST FLOW WILL GATHER MOISTURE FROM THE GREAT LAKES
AND DEPOSIT IT AS SNOW SHOWERS ACROSS THE ALLEGHENY MOUNTAINS
TONIGHT AND FRIDAY. SOME OF THE HEAVIEST SNOW SHOWERS WITH
IFR VSBYS WILL LIKELY OCCUR BTWN 04Z-08Z AT JST WITH PASSAGE OF A
WEAK SFC TROUGH. LATEST RUC SHOWS A TONGUE OF HIGHER LOW LVL
MOISTURE ALONG THIS BOUNDARY SAGGING SOUTH INTO THE LAUREL
HIGHLANDS DURING THIS TIME PERIOD. DRYING...DOWNSLOPING FLOW
SHOULD RESULT IN MUCH BETTER FLYING CONDS OVERNIGHT EAST OF THE
MTNS. CAN/T RULE OUT BRIEF VSBY RESTRICTIONS OVERNIGHT AT
AOO/UNV/IPT...WHILE CONDS AT MDT AND LNS APPEAR VERY LIKELY TO
REMAIN VFR.
EXPECT DIMINISHING -SHSN OVR THE W MTNS ON FRIDAY...AS INVERSION
HEIGHTS LOWER WITH APPROACH OF SFC HIGH. STILL...OCNL MVFR
CIGS/VSBYS REMAIN POSSIBLE AT BFD THRU FRI EVENING. AN INTENSE LOW
PRES SYSTEM OVR THE CANADIAN MARITIMES WILL CONTINUE TO BUFFET THE
AREA WITH A GUSTY WNW WINDS. ALTHOUGH THE GUSTS MAY DIMINISH A BIT
OVERNIGHT...BUFKIT SOUNDINGS SUPPORT WIDESPREAD GUSTS ARND 25KTS
DURING LATE FRI AM AND AFTERNOON.
OUTLOOK...
SAT...NO SIG WX EXPECTED.
SUN...SNOW POSS LATE ACROSS THE SOUTH.
MON...SNOW POSS...ESP SOUTH.
TUE...SNOW POSS...ESP LAUREL HIGHLANDS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
LAKE EFFECT SNOW ADVISORY UNTIL NOON EDT TODAY FOR PAZ004.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...LA CORTE
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1137 PM CDT THU MAR 21 2013
.AVIATION...
MVFR CIGS MOVING NORTH FROM THE GULF NOW AND ARE ALMOST AT TAF
SITES...SO WILL START 06Z TAFS WITH MVFR. HAVE BACKED UP
METROPLEX FROPA A BIT BASED ON NAM/RAP GUIDANCE...AND STILL FEEL
CLOUDS WILL BE VERY SLOW TO BREAK FRIDAY AFTERNOON. WHEN THEY
DO...CLEAR SKIES NORTH OF THE FRONT WITH LIGHT NORTHEAST FLOW
WILL ALLOW TEMPERATURES TO COOL TO SATURATION LATE FRIDAY NIGHT
AND HAVE INCLUDED IFR CIG/VSBY IN THE EXTENDED PORTION OF DFW
TAF. ALL TAF SITES WILL LIKELY BE IFR BEFORE SUNRISE SATURDAY
WITH WIDESPREAD FOG IN THE AREA. 84
&&
.UPDATE...
WEAK MOISTURE CONVERGENCE AND LIMITED INSTABILITY PREVENTED
THUNDERSTORM DEVELOPMENT ALONG THE DRY LINE THIS AFTERNOON/EARLY
THIS EVENING. NOW WITH THE LOSS OF SURFACE HEATING...STORM CHANCES
ALONG THE DRY LINE HAVE DECREASED SIGNIFICANTLY. THERE IS STILL A
CHANCE OF SOME ELEVATED SHOWERS AND THUNDERSTORMS ACROSS THE
NORTHERN HALF OF NORTH TEXAS WITH THE BEST STORM CHANCES ACROSS
THE NORTHEAST ZONES JUST NORTH OF A WARM FRONT. FURTHER
SOUTH...SOME WARM AIR ADVECTION SHOWERS ARE POSSIBLE...ESPECIALLY
TOWARD MORNING.
FOR THIS UPDATE...WE WILL LOWER EVENING POPS IN ALL ZONES AND MAKE
SOME MINOR WIND/CLOUD COVER AND HOURLY TEMP/DEW POINT ADJUSTMENTS.
79
&&
.PREV DISCUSSION... /ISSUED 319 PM CDT THU MAR 21 2013/
BREEZY AND MOSTLY CLOUDY CONDITIONS CONTINUE ACROSS THE REGION
THIS EVENING BUT SOME CHANGES ARE STILL EXPECTED BY THE LATE
AFTERNOON AND EVENING HOURS. THE SURFACE LOW REMAINS OVER THE
TEXAS PANHANDLE WITH THE LEADING EDGE OF THE DRYLINE NOW LOCATED
ROUGHLY ALONG A LINE FROM VERNON TO SAN ANGELO. DEWPOINTS CONTINUE
TO INCREASE INTO THE LOWER 50S AHEAD OF THE DRYLINE BUT
INSTABILITY IS STILL LACKING. SATELLITE IMAGERY DEPICTS EVIDENCE
OF INCREASING LIFT APPROACHING THE REGION FROM THE WEST. SOME LOW
LEVEL CUMULUS HAS NOW DEVELOPED IN NORTHWEST TEXAS AND SOUTHWEST
OKLAHOMA AND MID LEVEL CLOUDS OVER WEST CENTRAL TEXAS ARE
LOOKING MORE ROBUST. INITIATION IS STILL POSSIBLE NEAR THE DRYLINE
LATE THIS AFTERNOON...AMONGST BREAKS IN THE MID LEVEL CLOUD DECK
BUT THE WINDOW FOR SEVERE POTENTIAL IS DECREASING. INITIATION NEAR
THE DRYLINE JUST WEST OF OUR CWA LIKELY WILL NOT BE UNTIL AFTER 5
PM AND THE SEVERE THREAT WILL BE DIMINISHING WITH THE LOSS OF
HEATING BY 8-9 PM. CONSIDERING THE LATEST TRENDS...WITH THE MID
LEVEL CLOUD COVER THAT IS STRETCHING BACK WEST...SBCAPES NEAR 1000
J/KG AS PREVIOUSLY PREDICTED MAY BE TOO HIGH AND VALUES WILL
REMAIN CLOSER TO 500-800 J/KG. CONVERGENCE ALONG THE DRYLINE IS
NOT VERY GOOD AT THIS TIME AS THE WINDS AHEAD OF THE DRYLINE ARE
ALSO FROM THE SOUTHWEST. THE RAP SHOWS THE SURFACE LOW REMAINING
IN THE TEXAS PANHANDLE FOR THE NEXT FEW HOURS WHICH MEANS THE SURFACE
WINDS WILL LIKELY NOT HAVE A CHANCE TO BACK AS THE DRYLINE MOVES
CLOSER. HOWEVER...WITH STRONG SHEAR...LIFT FROM A SERIES OF
SHORTWAVES MOVING NEAR THE REGION AND THE POTENTIAL FOR INCREASING
INSTABILITY OVER THE NEXT FEW HOURS...STILL EXPECT TO SEE A FEW
THUNDERSTORMS OVER OUR NORTHWESTERN COUNTIES WITH A FEW STRONG TO
SEVERE STORMS POSSIBLE. ANY STORMS THAT DO DEVELOP WILL LIKELY
MOVE EAST OR SOUTHEAST. LARGE HAIL AND DAMAGING WINDS WILL BE THE
MAIN THREATS.
EXPECT THE THUNDERSTORM ACTIVITY TO WANE FAIRLY QUICKLY AROUND OR
AFTER SUNSET BUT ADDITIONAL SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE OVER THE NORTHERN HALF OF THE REGION OVERNIGHT. THE
HIGHEST CHANCES FOR RAIN CONTINUE TO BE OVER THE NORTHEASTERN
COUNTIES. CANNOT RULE OUT A STRONG STORM OR TWO PRODUCING SMALL
HAIL AND/OR GUSTY WINDS BUT THE INSTABILITY OVERNIGHT IS FAIRLY
WEAK. A COLD FRONT WILL MOVE INTO THE REGION LATE TONIGHT AND
CONTINUE TO PROGRESS SOUTH THROUGH THE DAY TOMORROW. THERE
CONTINUES TO BE A CHANCE FOR RAIN AND ISOLATED THUNDERSTORMS OVER
THE EASTERN HALF OF THE REGION TOMORROW. WE COULD SEE A STRONG
STORM OR TWO OVER OUR FAR SOUTHEASTERN COUNTIES TOMORROW AFTERNOON
AHEAD OF THE FRONT.
THE FRONT WILL STALL JUST SOUTH OF THE CWA FRIDAY NIGHT AND THEN
RETREAT NORTH AS A WARM FRONT ON SATURDAY. AS THE WARM FRONT LIFTS
NORTH...WARM AIR ADVECTION OVER THE COOL SURFACE LAYER WILL RESULT
IN SCATTERED RAIN ACTIVITY THROUGHOUT THE DAY WITH ISOLATED
THUNDERSTORMS POSSIBLE. HIGHEST RAIN CHANCES WILL BE OVER THE
EASTERN HALF OF THE REGION. A STRONGER COLD FRONT WILL PUSH ACROSS
THE REGION SATURDAY NIGHT. THE RAIN WILL BE ENDING FROM WEST TO
EAST DURING THE DAY AS A DRYLINE MOVES ACROSS THE REGION. MUCH
COOLER AND DRIER AIR WILL SETTLE INTO THE REGION FOR SEVERAL DAYS
WITH TEMPERATURES FALLING BELOW NORMAL FOR AT LEAST THE FIRST HALF
OF NEXT WEEK. A FREEZE IS NOT EXPECTED REGION-WIDE ON ANY GIVEN
NIGHT BUT NEAR FREEZING TEMPERATURES WILL BE POSSIBLE MAINLY OVER
THE NORTHWESTERN HALF OF THE CWA SUNDAY AND MONDAY NIGHTS. TEMPERATURES
WILL START TO WARM LATER IN THE WEEK AND THE GFS IS MUCH FASTER TO
WARM TEMPERATURES THAN THE ECMWF.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 57 64 47 68 42 / 20 20 20 50 10
WACO, TX 62 71 50 74 42 / 10 20 20 50 5
PARIS, TX 48 58 45 58 37 / 50 30 20 50 20
DENTON, TX 51 60 45 65 39 / 30 20 20 40 10
MCKINNEY, TX 54 60 45 62 40 / 40 20 20 50 10
DALLAS, TX 58 64 48 68 43 / 20 20 20 50 10
TERRELL, TX 58 64 48 65 42 / 30 30 20 50 10
CORSICANA, TX 62 71 50 69 43 / 20 20 20 50 10
TEMPLE, TX 62 76 52 76 41 / 10 20 20 40 5
MINERAL WELLS, TX 50 63 46 74 39 / 20 10 20 30 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
752 AM CDT FRI MAR 22 2013
...UPDATED AVIATION SECTION...
.SYNOPSIS...
ISSUED AT 252 AM CDT FRI MAR 22 2013
THE BULK OF THE POLAR JET ENERGY WAS POSITIONED ACROSS THE SOUTHERN
ROCKIES, THROUGH THE SOUTHERN PLAINS, WRAPPING THROUGH THE SOUTHEAST
UNITED STATES JUST SOUTH OF THE NORTHEAST U.S. BROAD CLOSED LOW. A
SECOND SIGNIFICANT UPPER JET WAS DIVING SOUTHWARD ON THE HEELS OF
THE FIRST, INTO THE NORTHWEST PACIFIC REGION COASTLINE. THE MID
LEVELS EXHIBITS COLD 500 MB AIR TEMPERATURES BELOW -20 DEGREES
ACROSS MOST OF THE CONUS. THE AIR ASSOCIATED WITH THE 500 MB TROUGH
ACROSS THE NORTHWEST U.S. WAS -30 TO NEAR -40 DEGREES C. A STRONG
TEMPERATURE GRADIENT REMAINED IN PLACE FROM CENTRAL KANSAS, WHICH
MARKED THE EDGE OF THE FREEZING AT AT THE 850 MB LEVEL...TO THE
TEXAS PANHANDLE WHERE WARM +20 DEGREE C AIR WAS IN PLACE. RAIN AND
SNOW WERE FALLING ACROSS NORTHWEST KANSAS INTO SOUTH CENTRAL
NEBRASKA, ASSOCIATED WITH A STRONG BAROCLINIC ZONE AND ISENTROPIC
LIFT.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 252 AM CDT FRI MAR 22 2013
NUMEROUS SNOW SHOWERS CONTINUE TO DRIFT FROM WEST CENTRAL INTO
CENTRAL KANSAS THIS MORNING. THE HIGHEST CONCENTRATION OF SNOW
SHOWERS WILL MOVE THROUGH THE RUSH CENTER TO STAFFORD AND SAINT JOHNS
AREAS THOUGH 5 AM. AREAS TO THE SOUTH WILL FIND THE SHOWERS REALIZED
AS EITHER RAIN OR SNOW PRECIPITATION TYPE, AS WARMER TEMPERATURES
ARE FOUND NEAR THE OKLAHOMA LINE. BASED ON THE RAPID REFRESH THE
PRECIPITATION SHOULD CLEAR THE AREA BY 11 UTC. HOWEVER, LOW LEVEL
STRATUS WILL PERSIST THROUGH THE MORNING UNTIL THE STRONG MARCH SUN
CAN WARM THE BOUNDARY LAYER SUFFICIENTLY TO INDUCE MIXING. THE
LATEST NAM MODEL SUGGESTS THIS SHOULD OCCUR RAPIDLY BETWEEN 15 AND
18 UTC. AS A RESULT, DRY AIR IN WESTERN KANSAS WILL ALLOW RAPID
WARMING INTO THE 60S BY THE AFTERNOON, WHILE CENTRAL KANSAS COUNTIES
FROM HAYS TO PRATT AND MEDICINE LODGE WILL BE SLOWER TO RESPOND.
WEAK EASTERLY UPSLOPE WINDS SHOULD PERSIST THROUGH THE DAY, BEFORE
TURNING SLIGHTLY MORE SOUTHEASTERLY FOR A FEW HOURS IN RESPONSE TO
SURFACE CYCLOGENESIS OVER EASTERN COLORADO THROUGH THE EVENING AND
INTO TONIGHT.
WITH THE COOL STABLE BOUNDARY LAYER AIRMASS ACROSS CENTRAL KANSAS IN
PLACE, RAPID STRATUS REDEVELOPMENT SHOULD OCCUR AGAIN BEFORE
MIDNIGHT. MODEL CONSENSUS INDICATES WARM ADVECTION PRECIPITATION
CONVECTIVE SHOWERS ARE POSSIBLE THIS EVENING ACROSS THE FAR
SOUTHWEST KANSAS COUNTIES, ASSOCIATED WITH THE NEXT SYNOPTIC SCALE
STORM. CHANCES ARE GOOD THAT THE INITIAL SHOWERS WILL BECOME MORE
NUMEROUS THROUGH THE OVERNIGHT HOURS, AND LIKELY QUICKLY CAUSE
SURFACE TEMPERATURES ACROSS WESTERN KANSAS TO DROP TO THE WET BULB
TEMPERATURE CAUSING A PHASE CHANGE TO SNOW OVERNIGHT. AN INCH OR TWO
OF SNOW COULD BE POSSIBLE ACROSS ANY AREAS OF WEST CENTRAL KANSAS
THROUGH THE INTERSTATE 70 CORRIDOR BY 12Z SATURDAY.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 429 AM CDT FRI MAR 22 2013
WINTER STORM STILL THE FOCUS OF THE LONG TERM SECTION...WITH IMPACTS
THE MAIN CHALLENGE...IN TERMS OF TIMING AND SEVERITY...AND WHO WILL
GET THE BRUNT OF THE STORM.
400MB POTENTIAL VORTICITY (PV) STREAM EVIDENT ON RAP ANALYSIS AND
WATER VAPOR LOOP THIS MORNING FROM SOUTHWESTER BRITISH COLUMBIA TO
SOUTHWESTERN IDAHO. THIS STREAM OF HIGH PV AIR WILL AID IN THE
FORMATION OF A MID LEVEL CYCLONE BY EARLY SATURDAY OVER WESTERN
COLORADO. THE INCREASED UPPER TROPOSPHERIC JET STREAK DYNAMICS
ASSOCIATED WITH THE STORM WILL AID IN LOW LEVEL CYCLOGENESIS AS WELL
BY EARLY SATURDAY MORNING. SATURATION WILL OCCUR IN THE LOW LEVELS
WITH INITIAL PRECIPITATION BREAKING OUT LATE IN THE FRIDAY NIGHT
PERIOD INTO EARLY SATURDAY AS WARM, MOIST FRONTOGENESIS INCREASES
DRAMATICALLY IN THE 800-700MB LAYER. AS THE LOWER-MID TROPOSPHERIC
COLUMN SATURATES EARLY SATURDAY...THE VERTICAL THERMODYNAMIC PROFILE
WILL QUICKLY SUPPORT SNOW AS THE PROFILE GOES BELOW ZERO DEGC OVER
MUCH OF SOUTHWEST KANSAS...ESPECIALLY BY 18Z SATURDAY. THE SNOW WILL
INITIALLY BE A VERY WET SNOW AS SURFACE TEMPERATURES WILL BE IN THE
32 TO 35 DEGREE RANGE WITH A PREDOMINANTLY EAST TO EAST-NORTHEAST
SURFACE WIND THROUGH MIDDAY. BY AFTERNOON...SURFACE TEMPERATURES
WILL APPROACH 30 AND LOW LEVEL COLD ADVECTION WILL INCREASE WHICH
WILL ENHANCE THE DROP IN TEMPERATURE...ESPECIALLY WEST OF HIGHWAY
83. THE WINDS WEST OF HIGHWAY 83 WILL BECOME NORTH AND INCREASE TO
25 TO 30 MPH. THERE IS SOME CONCERN THAT GIVEN THE MAGNITUDE OF WIND
AND POTENTIAL ONE HALF TO ONE-INCH PER HOUR SNOWFALL RATES BY LATE
IN THE DAY...THAT WHITE-OUT OR NEAR WHITE-OUT CONDITIONS WILL OCCUR.
THE SNOW WILL BECOME INCREASINGLY SUSCEPTIBLE TO BLOWING AS
TEMPERATURES FALL INTO THE UPPER 20S BY 00Z AS FAR EAST AS HIGHWAY
283 (WAKEENEY TO DODGE CITY TO ASHLAND LINE). TEMPERATURE AND TIME
OF DAY WILL HAVE A HUGE IMPACT ON THE BLOWING AND DRIFTING OF
SNOW...LEADING TO THE NEAR-BLIZZARD OR EVEN BLIZZARD THREAT. IF THE
BRUNT OF THE STORM WAS TO OCCUR DURING THE MIDDLE OF THE DAY WITH
SURFACE TEMPERATURES IN THE 32 TO 34 DEGREE RANGE...THE THREAT FOR
BLOWING SNOW WOULD BE GREATLY REDUCED DUE TO THE VERY WET NATURE AND
COMPOSITION OF SNOW (LARGE, WET AGGREGATE FLAKES VS. DRIER
INDIVIDUAL DENDRITES). THE DENDRITIC GROWTH ZONE (-12C TO -16C) WILL
BE IN THE FAVORED 750-650MB LAYER DURING THE 00-09Z TIME FRAME
SUNDAY IN THE MID LEVEL DEFORMATION ZONE WHICH WILL AID IN SLIGHTLY
HIGHER SNOWFALL RATIO THAN WHAT WOULD TYPICALLY BE EXPECTED FOR LATE
MARCH...SO THIS IS SOMETHING TO KEEP IN MIND AS WELL.
GIVEN ALL OF THE ABOVE MENTIONED...AND WITH THE MID LEVEL
FRONTOGENETIC ZONE LIKELY JUST FAR ENOUGH SOUTH TO IMPACT THE
SOUTHERN COUNTIES (USING THE ECMWF AND CANADIAN GEM MORE SOUTHERN
SCENARIO)...WILL ISSUE A WINTER WEATHER ADVISORY IN THE SOUTHERN
COUNTIES NOT CURRENTLY IN THE WINTER STORM WATCH (ROUGHLY ARKANSAS
RIVER SOUTH TO THE OKLAHOMA BORDER). AS FAR AS STORM TOTAL SNOWFALL
AMOUNTS GO...THIS IS STILL A VERY DIFFICULT FORECAST AND WILL LIKELY
COME DOWN TO THE MESOSCALE COMPONENTS OF THE STORM ITSELF (AS IS
TYPICALLY THE CASE). THAT BEING SAID...IT STILL LOOKS LIKE THE
NORTHERN HALF OF THE FORECAST AREA (ARKANSAS RIVER TO INTERSTATE 700
WILL SEE TOTAL SNOWFALL IN THE 4 TO 7 INCH RANGE WITH A FEW 8 INCH
AMOUNTS POSSIBLE IN SOME SPOTS. FROM THE ARKANSAS RIVER SOUTH TO THE
OKLAHOMA BORDER...3 TO 5 INCHES IS THE FORECAST.
THE STORM WILL QUICKLY EXIT EAST SUNDAY MORNING WITH SOME REMNANT
LIGHT BLOWING AND DRIFTING THROUGH THE MORNING HOURS AFTER SUNRISE
SUNDAY. THE MARCH SUN WILL AID IN SNOWMELT ON ROAD SURFACES...BUT IT
WILL HAVE SOME WORK TO DO AS STRONG COLD ADVECTION WILL CONTINUE
THROUGH THE DAY AND 2-METER TEMPERATURES WILL STAY IN THE 20S MOST
OF THE DAY.
UNFORTUNATELY...HAVE HAD NO TIME TO ADDRESS THE FORECAST BEYOND
SUNDAY AND RUNNING WITH THE LATEST ALLBLEND GUIDANCE WHICH CALLS FOR
A SLOW WARM-UP MONDAY AND TUESDAY (30S AND 40S). BY WEDNESDAY...WE
SHOULD SEE A FAIRLY DRAMATIC WARM-UP BACK INTO THE 50S AND PERHAPS
60S. AFTER THIS BRIEF WARM-UP BACK TO CLIMO...WE WILL MOST LIKELY
ENTER ANOTHER COLD SPELL GOING INTO THE DAY 7-10 TIME FRAME AS WE
END THE MONTH OF MARCH.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 746 AM CDT FRI MAR 22 2013
MAIN IMPACT ON AVIATION WILL BE THE DEVELOPMENT OF IFR/LIFR
CEILINGS OVERNIGHT TONIGHT AS LOW PRESSURE DEVELOPS IN ADVANCE OF
THE APPROACHING WINTER STORM. CEILINGS WILL DETERIORATE QUICKLY
AROUND THE 08-10Z TIME FRAME AT DDC, GCK, AND HYS. PRECIPITATION
IN THE FORM OF SNOW WILL DEVELOP SHORTLY AFTER DAYBREAK SATURDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 52 35 35 23 / 10 80 90 90
GCK 52 33 33 21 / 10 90 90 90
EHA 56 37 37 21 / 20 90 90 80
LBL 56 38 38 23 / 10 80 90 80
HYS 48 30 31 23 / 10 90 90 90
P28 52 36 38 28 / 10 50 90 80
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
KSZ030-031-043>046-061>066.
WINTER WEATHER ADVISORY FROM 10 AM SATURDAY TO 7 AM CDT SUNDAY
FOR KSZ074>081-084>090.
&&
$$
SYNOPSIS...RUSSELL
SHORT TERM...RUSSELL
LONG TERM...UMSCHEID
AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1040 AM EDT FRI MAR 22 2013
.UPDATE...
ISSUED AT 1040 AM EDT FRI MAR 22 2013
SOME SLIGHTLY DEEPER MOISTURE HAS MOVED INTO THE AREA...JUST ENOUGH
TO ALLOW SOME SNOW TO MIX IN WITH THE FREEZING DRIZZLE DUE TO THE
TOP OF THE CLOUD BEING AROUND -12C. HOWEVER...THIS IS EXPECTED TO
ONLY LAST A FEW HOURS PER THE RAP SOUNDINGS. OTHERWISE...HAVE OPTED
TO KEEP FREEZING DRIZZLE AROUND FOR MUCH OF THE DAY CLOSER TO LAKE
SUPERIOR DUE TO THE PERSISTENT UPSLOPE FLOW THROUGH THE DAY AND
SHALLOW MOISTURE. ANY SURFACES THAT ARE UNTREATED MAY BE SLIPPERY AT
TIMES.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 505 AM EDT FRI MAR 22 2013
UPR LEVEL TROUGH DRIFTS FARTHER EAST OF UPR LAKES WITH RIDGING
POISED TO MOVE IN FOR THE WEEKEND. STRONG SFC LOW SPINS NEAR
CANADIAN MARITIMES WITH WEAKER LOW OVER QUEBEC. WEAK TROUGH STILL
EXTENDS WESTWARD ACROSS UPR LAKES REGION FROM THE QUEBEC LOW. HIGH
PRESSURE UPSTREAM OVER MANITOBA WILL ONLY SLOWLY MOVE TOWARD GREAT
LAKES. RESULT IS WEAK CYCLONIC/NEUTRAL LOW-LEVEL FLOW THAT KEEPS
CHANCES OF SNOW SHOWERS/FLURRIES IN THROUGH SATURDAY. AT A MINIMUM...
SKIES ACROSS MUCH OF CWA WILL TEND TO STAY ON THE CLOUDIER SIDE.
BETTER PRECIP CHANCES...AND THEY ARE ON THE SMALLER SIDE...OCCUR
TODAY AS H95-H9 TROUGH DROPS ACROSS LK SUPERIOR INTO NORTHERN CWA
THIS MORNING. PLENTY OF H95-H9 MOISTURE SEEN UPSTREAM IN ONTARIO ON
00Z YPL AND WZC SOUNDINGS. GENERALLY NAM/GFS/LOCAL-WRF INITIALIZED
YPL SOUNDING WELL BUT WERE TOO MOIST ABOVE H95 AT MOOSINEE. ONCE THE
MOISTURE ARRIVES THROUGH 12Z...THINK IT WILL UPSLOPE AND BE LIFTED
OVER COLD DOME OF AIR IN PLACE AND GRADUALLY LOWER/THICKEN. 925-900MB
TEMPS OF -8C TO -10C JUST COLD ENOUGH FOR LK EFFECT SNOW SHOWERS OR
FLURRIES. COVERAGE WILL BE SPOTTY THOUGH AS OVER-WATER INSTABILITY
IS MARGINAL. PUT SOME FZDZ IN EARLIER AS THERE WERE REPORTS UPSTREAM
IN ONTARIO WITH CIGS BLO 010. CIGS THUS FAR OVR UPR MICHIGAN ARE
MORE TOWARD 2KFT WHICH SEEMS TOO HIGH TO SEE ENOUGH SATURATION FOR
FZDZ. WILL PULL THE MENTION OF FZDZ.
STAYED PESSIMISTIC FOR CLOUD COVER TONIGHT GIVEN AMOUNT OF MOISTURE
UPSTREAM. BUT...TONIGHT THERE IS ALSO MORE DIFFLUENT SFC-H9 FLOW SO
CONVERGENCE WILL BE AT A PREMIUM...LEADING TO BREAKS DEVELOPING IN
THE CLOUD COVER. OTHER THAN ISOLD SHSN IN THE EVENING OVR MARQUETTE
COUNTY WITH WEAK ONSHORE/UPSLOPE FLOW...KEPT FORECAST DRY FOR
TONIGHT. MIN TEMPS WILL BE TRICKY AS IT WILL ALL DEPEND ON WHERE
CLOUDS PERSIST. BETTER CHANCE FOR CLEARING WOULD BE OVER SW CWA WITH
MORE OF SIGNAL FOR LGT AND DIFFLUENT WINDS. MIN TEMPS IN THAT AREA
MAY DROP TO 5 ABOVE. ELSEWHERE WITH THE CLOUDS AND SOME WIND...MIN
TEMPS SHOULD STAY IN THE TEENS. ALL IN ALL...PRETTY QUIET WEATHER
COMPARED TO THE ACTIVE WEATHER PATTERN EXPERIENCED RECENTLY.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 505 AM EDT FRI MAR 22 2013
A BLOCKING PATTERN WITH HIGH LATITUDE RIDGING FROM GREENLAND INTO
NORTHEAST CANADA IS EXPECTED TO PERSIST THROUGH THE PERIOD. THIS WILL
RESULT IN TROUGHING INTO THE N CNTRL AND ERN CONUS KEEPING BELOW
NORMAL TEMPS IN PLACE. HIGHS IN THE LOWER TO MID 30S ARE EXPECTED
WITH LOWS GENERALLY IN THE TEENS TO LOWER 20S.
SAT INTO SAT NIGHT...EVEN THOUGH MODELS SHOW LARGE SCALE SUBSIDENCE
PREVAILING...WITH PERSISTENT NRLY FLOW AND 825-800MB MOISTURE ALONG
WITH 850 MB TEMPS IN THE -10C TO -12C RANGE...SOME LIGHT LAKE EFFECT
SNOW SHOWERS OR FLURRIES WILL REMAIN POSSIBLE. WITH GREATER LATE
MARCH DAYTIME HEATING...A DIURNAL COMPONENT TO THE -SHSN IS ALSO
EXPECTED. SO...ANY FLURRIES SHOULD DIMINISH DURING THE EVENING.
SUN AND MON...AS A MID LEVEL LOW MOVES EAST FROM THE OHIO
VALLEY...THE GFS/ECMWF SUGGEST THAT ANOTHER BATCH OF 850-700 MB
MOISTURE WILL BE DRAWN TOWARD UPPER MICHIGAN FROM THE NORTHEAST. THE
MOISTURE COMBINED WITH NNE FLOW 850 MB TEMPS REMAINING IN THE -10C
TO -12C RANGE WILL BE ENOUGH TO SUPPORT SNOW SHOWERS CHANCES INTO
THE NW HALF OF THE CWA MON THAT MAY LINGER INTO MON NIGHT.
HOWEVER...ANY SNOWFALL AMOUNT SHOULD REMAIN LIGHT...LESS THAN A HALF
INCH.
TUE-THU...THE ECMWF/GEM WERE SLOWER WITH THE COMPACT MID LEVEL LOW
THAT IS EXPECTED TO SLIDE FROM CNTRL CANADA INTO THE UPPER MS VALLEY
OF WRN GREAT LAKES COMPARED TO THE GFS. DESPITE MODEL DIFFERENCES
REGARDING THIS FEATURE...THE PERSISTENT NRLY LOW LEVEL FLOW PATTERN
WILL KEEP POTENTIAL FOR SOME LIGHT SNOW OR FLURRIES GOING. SINCE ANY
SHORTWAVES IN THE NW MID LEVEL FLOW WILL BE WEAK...EXPECT CHANCE FOR
ANY MEASURABLE SNOW WILL REMAIN ONLY SLIGHT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 745 AM EDT FRI MAR 22 2013
LOW-LEVEL MOISTURE HAS RETURNED TO ALL THE TAF SITES THIS MORNING.
EXPECT LOWER MVFR AND EVEN IFR CIGS THROUGH MORNING. MAY SEE -SHSN
AND FZDZ AT TIMES THIS MORNING. FZDZ PATCHY ENOUGH AT THIS POINT TO
KEEP OUT OF TAFS. EXPECT CLOUDS TO SCATTER OUT THIS EVENING AT IWD
WITH DIFFLUENT LOW-LEVEL WINDS. OTHERWISE...PLAN ON BKN-OVC LOWER
MVFR CIGS CMX AND SAW THROUGH END OF TAF PERIOD WITH PERSISTENT LIGHT
NORTHERLY WINDS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 505 AM EDT FRI MAR 22 2013
HIGH PRESSURE OVER CNTRL CANADA EXPANDS INTO THE GREAT LAKES THROUGH
NEXT WEEK. PLAN ON QUIET CONDITIONS ON LK SUPERIOR WITH WINDS LESS
THAN 25 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...MRD
SHORT TERM...JLA
LONG TERM...JLB
AVIATION...JLA
MARINE...JLA
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
753 AM EDT FRI MAR 22 2013
.UPDATE...
ISSUED AT 745 AM EDT FRI MAR 22 2013
FREEZING DRIZZLE HAS INDEED DEVELOPED...AFTER IT WAS REMOVED FROM
FCST. SO IT GOES. ALSO SOME FLURRIES TOO SO IT APPEARS WE ARE RIGHT
ON THE THRESHOLD FOR ICE NUCLEATION. RUC13 925MB TEMPS AROUND -8C SO
THIS MAKES SOME SENSE. ADDED AREAS OF FREEZING DRIZZLE IN OVER HIGHER
TERRAIN OF NW AND NCNTRL UPR MICHIGAN FOR NOW. ALSO PUT OUT SPECIAL
WEATHER STATEMENT AND UPDATED SOCIAL MEDIA TO HIGHLIGHT HAZARD. FOR A
START KEPT MENTION OF FZDZ THROUGH THE MORNING. WOULD THINK THERE MAY
BE ENOUGH MIXING OUT OF NEAR SFC MOISTURE FOR FZDZ TO DISSIPATE BY
AFTN. POSSIBLE THAT FZDZ COULD CONTINUE LONGER FOR UPSLOPE AREAS BUT
NOT QUITE SURE SO WILL LET DAYSHIFT MAKE THAT ADJUSTMENT IF NEEDED.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 505 AM EDT FRI MAR 22 2013
UPR LEVEL TROUGH DRIFTS FARTHER EAST OF UPR LAKES WITH RIDGING
POISED TO MOVE IN FOR THE WEEKEND. STRONG SFC LOW SPINS NEAR
CANADIAN MARITIMES WITH WEAKER LOW OVER QUEBEC. WEAK TROUGH STILL
EXTENDS WESTWARD ACROSS UPR LAKES REGION FROM THE QUEBEC LOW. HIGH
PRESSURE UPSTREAM OVER MANITOBA WILL ONLY SLOWLY MOVE TOWARD GREAT
LAKES. RESULT IS WEAK CYCLONIC/NEUTRAL LOW-LEVEL FLOW THAT KEEPS
CHANCES OF SNOW SHOWERS/FLURRIES IN THROUGH SATURDAY. AT A MINIMUM...
SKIES ACROSS MUCH OF CWA WILL TEND TO STAY ON THE CLOUDIER SIDE.
BETTER PRECIP CHANCES...AND THEY ARE ON THE SMALLER SIDE...OCCUR
TODAY AS H95-H9 TROUGH DROPS ACROSS LK SUPERIOR INTO NORTHERN CWA
THIS MORNING. PLENTY OF H95-H9 MOISTURE SEEN UPSTREAM IN ONTARIO ON
00Z YPL AND WZC SOUNDINGS. GENERALLY NAM/GFS/LOCAL-WRF INITIALIZED
YPL SOUNDING WELL BUT WERE TOO MOIST ABOVE H95 AT MOOSINEE. ONCE THE
MOISTURE ARRIVES THROUGH 12Z...THINK IT WILL UPSLOPE AND BE LIFTED
OVER COLD DOME OF AIR IN PLACE AND GRADUALLY LOWER/THICKEN. 925-900MB
TEMPS OF -8C TO -10C JUST COLD ENOUGH FOR LK EFFECT SNOW SHOWERS OR
FLURRIES. COVERAGE WILL BE SPOTTY THOUGH AS OVER-WATER INSTABILITY
IS MARGINAL. PUT SOME FZDZ IN EARLIER AS THERE WERE REPORTS UPSTREAM
IN ONTARIO WITH CIGS BLO 010. CIGS THUS FAR OVR UPR MICHIGAN ARE
MORE TOWARD 2KFT WHICH SEEMS TOO HIGH TO SEE ENOUGH SATURATION FOR
FZDZ. WILL PULL THE MENTION OF FZDZ.
STAYED PESSIMISTIC FOR CLOUD COVER TONIGHT GIVEN AMOUNT OF MOISTURE
UPSTREAM. BUT...TONIGHT THERE IS ALSO MORE DIFFLUENT SFC-H9 FLOW SO
CONVERGENCE WILL BE AT A PREMIUM...LEADING TO BREAKS DEVELOPING IN
THE CLOUD COVER. OTHER THAN ISOLD SHSN IN THE EVENING OVR MARQUETTE
COUNTY WITH WEAK ONSHORE/UPSLOPE FLOW...KEPT FORECAST DRY FOR
TONIGHT. MIN TEMPS WILL BE TRICKY AS IT WILL ALL DEPEND ON WHERE
CLOUDS PERSIST. BETTER CHANCE FOR CLEARING WOULD BE OVER SW CWA WITH
MORE OF SIGNAL FOR LGT AND DIFFLUENT WINDS. MIN TEMPS IN THAT AREA
MAY DROP TO 5 ABOVE. ELSEWHERE WITH THE CLOUDS AND SOME WIND...MIN
TEMPS SHOULD STAY IN THE TEENS. ALL IN ALL...PRETTY QUIET WEATHER
COMPARED TO THE ACTIVE WEATHER PATTERN EXPERIENCED RECENTLY.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 505 AM EDT FRI MAR 22 2013
A BLOCKING PATTERN WITH HIGH LATITUDE RIDGING FROM GREENLAND INTO
NORTHEAST CANADA IS EXPECTED TO PERSIST THROUGH THE PERIOD. THIS WILL
RESULT IN TROUGHING INTO THE N CNTRL AND ERN CONUS KEEPING BELOW
NORMAL TEMPS IN PLACE. HIGHS IN THE LOWER TO MID 30S ARE EXPECTED
WITH LOWS GENERALLY IN THE TEENS TO LOWER 20S.
SAT INTO SAT NIGHT...EVEN THOUGH MODELS SHOW LARGE SCALE SUBSIDENCE
PREVAILING...WITH PERSISTENT NRLY FLOW AND 825-800MB MOISTURE ALONG
WITH 850 MB TEMPS IN THE -10C TO -12C RANGE...SOME LIGHT LAKE EFFECT
SNOW SHOWERS OR FLURRIES WILL REMAIN POSSIBLE. WITH GREATER LATE
MARCH DAYTIME HEATING...A DIURNAL COMPONENT TO THE -SHSN IS ALSO
EXPECTED. SO...ANY FLURRIES SHOULD DIMINISH DURING THE EVENING.
SUN AND MON...AS A MID LEVEL LOW MOVES EAST FROM THE OHIO
VALLEY...THE GFS/ECMWF SUGGEST THAT ANOTHER BATCH OF 850-700 MB
MOISTURE WILL BE DRAWN TOWARD UPPER MICHIGAN FROM THE NORTHEAST. THE
MOISTURE COMBINED WITH NNE FLOW 850 MB TEMPS REMAINING IN THE -10C
TO -12C RANGE WILL BE ENOUGH TO SUPPORT SNOW SHOWERS CHANCES INTO
THE NW HALF OF THE CWA MON THAT MAY LINGER INTO MON NIGHT.
HOWEVER...ANY SNOWFALL AMOUNT SHOULD REMAIN LIGHT...LESS THAN A HALF
INCH.
TUE-THU...THE ECMWF/GEM WERE SLOWER WITH THE COMPACT MID LEVEL LOW
THAT IS EXPECTED TO SLIDE FROM CNTRL CANADA INTO THE UPPER MS VALLEY
OF WRN GREAT LAKES COMPARED TO THE GFS. DESPITE MODEL DIFFERENCES
REGARDING THIS FEATURE...THE PERSISTENT NRLY LOW LEVEL FLOW PATTERN
WILL KEEP POTENTIAL FOR SOME LIGHT SNOW OR FLURRIES GOING. SINCE ANY
SHORTWAVES IN THE NW MID LEVEL FLOW WILL BE WEAK...EXPECT CHANCE FOR
ANY MEASURABLE SNOW WILL REMAIN ONLY SLIGHT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 745 AM EDT FRI MAR 22 2013
LOW-LEVEL MOISTURE HAS RETURNED TO ALL THE TAF SITES THIS MORNING.
EXPECT LOWER MVFR AND EVEN IFR CIGS THROUGH MORNING. MAY SEE -SHSN
AND FZDZ AT TIMES THIS MORNING. FZDZ PATCHY ENOUGH AT THIS POINT TO
KEEP OUT OF TAFS. EXPECT CLOUDS TO SCATTER OUT THIS EVENING AT IWD
WITH DIFFLUENT LOW-LEVEL WINDS. OTHERWISE...PLAN ON BKN-OVC LOWER
MVFR CIGS CMX AND SAW THROUGH END OF TAF PERIOD WITH PERSISTENT LIGHT
NORTHERLY WINDS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 505 AM EDT FRI MAR 22 2013
HIGH PRESSURE OVER CNTRL CANADA EXPANDS INTO THE GREAT LAKES THROUGH
NEXT WEEK. PLAN ON QUIET CONDITIONS ON LK SUPERIOR WITH WINDS LESS
THAN 25 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SHORT TERM...JLA
LONG TERM...JLB
AVIATION...JLA
MARINE...JLA
AREA FORECAST DISCUSSION
NWS DULUTH MN
924 AM CDT FRI MAR 22 2013
.UPDATE...PROGRESSIONS OF CLOUDS THROUGH THE ARROWHEAD AND ALONG
THE INTERNATIONAL BORDER HAS SLOWED QUITE A BIT. THERE IS SOME
EROSION OCCURRING ALONG THE LEADING EDGE. HAVE UPDATED THE SKY
GRIDS TO ACCOUNT FOR THIS TREND. RAISED MAX TEMPS A BIT AS TEMPS
ARE RECOVERING QUICKLY WHERE THERE IS FULL SUN...AND ESPECIALLY IN
THE FORESTED AREAS IN NW WI. BROUGHT DEWPOINTS UP AS WELL FOR THE
SAME REASON.
&&
.PREV DISCUSSION... /ISSUED 652 AM CDT FRI MAR 22 2013/
AVIATION...12Z TAF ISSUANCE.
A WIDESPREAD STRATUS DECK WITH CEILINGS OF 1-2 KFT IS CURRENTLY
RESIDING OVER ONTARIO...SINKING GRADUALLY OVER NE MINNESOTA AND
WESTERN LAKE SUPERIOR. EXPECTING THE LOW CLOUDS AND MVFR CIGS TO MAINLY
AFFECT THE KINL/KHIB/KDLH TERMINALS THROUGH 18Z...WHERE HAVE
HANDLED WITH TEMPO GROUPS AT THIS TIME. LATEST MODEL RUNS SUGGEST
THE LOW CLOUDS RETREAT BACK TO THE NORTHEAST THROUGH THE LATE
MORNING AND ALLOW WIDESPREAD VFR CIGS ACROSS ALL TERMINALS THIS
AFTERNOON. HOWEVER...THE ANTICIPATED CLEARING IN THE NORTHERN
ZONES WILL BE SHORT LIVED AS ANOTHER ROUND OF LOW CLOUDS ARE
FORECAST TO SPREAD BACK INTO THE REGION OVERNIGHT...MAINLY AFTER
02Z.
PREV DISCUSSION... /ISSUED 259 AM CDT FRI MAR 22 2013/
SHORT TERM...THROUGH SATURDAY.
THE NORTHLAND WILL REMAIN BETWEEN UPPER TROUGHS TODAY...WITH
NARROW RIDGING...THEN WE WILL BECOME INCREASINGLY UNDER THE
INFLUENCE OF THE WESTERN TROUGH AS IT MOVES TOWARD THE REGION
TONIGHT INTO SATURDAY.
THE MAIN FOCUS TODAY WILL BE ON CLOUD COVER...AS LOW LEVEL
NORTHEASTERLY FLOW WAS ALREADY SPREADING CLOUDS INTO THE THE
ARROWHEAD AND THROUGH NORTHWEST ONTARIO. THE NAM...ECMWF AND THE
RAP...WERE DOING A DECENT JOB HANDLING THESE CLOUDS THIS MORNING.
THE ECMWF SUGGESTS THE CLOUDS WILL DIMINISH THIS AFTERNOON...THE
RAP HOLDS THEM IN TODAY AND SPREADS THEM WELL SOUTH INTO OUR CWA.
THE NAM IS A COMPROMISE. WE DO EXPECT SOME THINNING OF THOSE
CLOUDS THIS AFTERNOON...THE RAP WAS WAY OVERDONE YESTERDAY. WE
INCREASED SKY COVER OVER THE NORTHERN AND EASTERN CWA
TODAY...ESPECIALLY THIS MORNING. WE KEPT THE FORECAST DRY TODAY
INTO TONIGHT...BUT WOULD NOT BE SURPRISED IF SOME FLURRIES
DEVELOPED. OVERALL...WE EXPECT HIGHS TODAY FROM 29F TO 35F.
TONIGHT...WITH PERSISTENT LOW LEVEL NORTHEAST FLOW WE EXPECT THE
CLOUDS TO EXPAND WEST AND SOUTH THROUGH MUCH OF THE CWA AND HAVE
MOST AREAS MOSTLY CLOUDY TONIGHT INTO SATURDAY. THE CLOUDS SHOULD
HOLD TEMPS UP TONIGHT...AND WE HAVE THEM FROM 8F TO 14F. SOME
POCKETS OF COLDER TEMPS WILL BE POSSIBLE IN ANY AREAS THAT SEE AN
EXTENDED PERIOD OF MOSTLY CLEAR SKIES...SINCE WINDS WILL BE LIGHT.
A SHORTWAVE WILL ROTATE THROUGH THE AREA ON SATURDAY...AND SHOULD
BE ENOUGH TO SET OFF SOME FLURRIES. WE HAVE SCATTERED FLURRIES
MAINLY OVER OUR MINNESOTA ZONES...INTO FAR NORTHWEST WISCONSIN.
HIGHS SHOULD REBOUND TO 30F TO 35F FOR MOST AREAS.
LONG TERM...SAT NIGHT THROUGH FRIDAY.
THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT
OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH
OVER THE ROCKIES THROUGH THE WEEKEND WITH A PERSISTENT NORTH TO
NORTHEAST BDRY LAYER FLOW. MODELS IN GOOD AGREEMENT THAT A VORT MAX
EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST ACROSS THE SRN
PLAINS THROUGH SUNDAY. MEANWHILE...LATEST MODEL RUNS ARE SUGGESTING A
SHORT WAVE BREAKS FREE FROM MAIN FLOW AND LIFTS INTO THE UPPER
PLAINS. THE 00Z RUNS OF THE ECM/NAM/GFS ALL SHOW THE SHORT WAVE
BECOMES A CLOSED H50 LOW IN THE VCNTY OF MONTANA/WRN DAKOTAS BY
SUNDAY MORNING. ATTM...HAVE KEPT FCST DRY THROUGH THE WEEKEND AS THE
FORCING/PRECIP FROM THE WAVE IN THE DAKOTAS LOOKS TO REMAIN TO THE
WEST OF THE FA...WHILE THE SOUTHERN STREAM LOW STAYS WELL OFF TO THE
SOUTH. HOWEVER...RH FIELDS AND LATEST NAM BUFR SOUNDINGS CONTINUE TO
SHOW INCREASING LOW LEVEL MOISTURE SAT NIGHT/SUN...SO HAVE
INTRODUCED BROAD BRUSH FLURRIES DURING THIS TIME. THE ONSHORE WINDS
MAY ALLOW FOR ADDITIONAL LIFT/ENHANCEMENT TO PRODUCE A FEW LIGHT SNOW
SHOWERS ALONG SOUTH SHORE OF LAKE SUPERIOR SUNDAY THROUGH EARLY NEXT
WEEK.
BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS
MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST.
LATEST RUNS OF THE ECM/GEM/GFS ARE ALL SUGGESTING A H50 CLOSED LOW
RETROGRADES ACROSS HUDSON BAY AND TRACKS INTO MANITOBA THROUGH
MONDAY. FROM HERE THERE ARE LARGE MODEL DIFFERENCES IN THE TRACK OF
THE VORT MAX AS THE ECM KEEPS THE LOW NEARLY STATIONARY OVER
MANITOBA...WHILE THE GFS DROPS THE LOW ACROSS THE DLH CWA THROUGH
MID-WEEK.
&&
.POINT TEMPS/POPS...
DLH 30 15 32 17 / 0 10 10 10
INL 29 10 32 15 / 0 10 10 10
BRD 33 13 33 18 / 0 10 10 10
HYR 33 8 35 16 / 0 10 10 10
ASX 31 11 32 17 / 0 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...GSF
AREA FORECAST DISCUSSION
NWS DULUTH MN
652 AM CDT FRI MAR 22 2013
.AVIATION...12Z TAF ISSUANCE.
A WIDESPREAD STRATUS DECK WITH CEILINGS OF 1-2 KFT IS CURRENTLY
RESIDING OVER ONTARIO...SINKING GRADUALLY OVER NE MINNESOTA AND
WESTERN LAKE SUPERIOR. EXPECTING THE LOW CLOUDS AND MVFR CIGS TO MAINLY
AFFECT THE KINL/KHIB/KDLH TERMINALS THROUGH 18Z...WHERE HAVE
HANDLED WITH TEMPO GROUPS AT THIS TIME. LATEST MODEL RUNS SUGGEST
THE LOW CLOUDS RETREAT BACK TO THE NORTHEAST THROUGH THE LATE
MORNING AND ALLOW WIDESPREAD VFR CIGS ACROSS ALL TERMINALS THIS
AFTERNOON. HOWEVER...THE ANTICIPATED CLEARING IN THE NORTHERN
ZONES WILL BE SHORT LIVED AS ANOTHER ROUND OF LOW CLOUDS ARE
FORECAST TO SPREAD BACK INTO THE REGION OVERNIGHT...MAINLY AFTER
02Z.
&&
.PREV DISCUSSION... /ISSUED 259 AM CDT FRI MAR 22 2013/
SHORT TERM...THROUGH SATURDAY.
THE NORTHLAND WILL REMAIN BETWEEN UPPER TROUGHS TODAY...WITH
NARROW RIDGING...THEN WE WILL BECOME INCREASINGLY UNDER THE
INFLUENCE OF THE WESTERN TROUGH AS IT MOVES TOWARD THE REGION
TONIGHT INTO SATURDAY.
THE MAIN FOCUS TODAY WILL BE ON CLOUD COVER...AS LOW LEVEL
NORTHEASTERLY FLOW WAS ALREADY SPREADING CLOUDS INTO THE THE
ARROWHEAD AND THROUGH NORTHWEST ONTARIO. THE NAM...ECMWF AND THE
RAP...WERE DOING A DECENT JOB HANDLING THESE CLOUDS THIS MORNING.
THE ECMWF SUGGESTS THE CLOUDS WILL DIMINISH THIS AFTERNOON...THE
RAP HOLDS THEM IN TODAY AND SPREADS THEM WELL SOUTH INTO OUR CWA.
THE NAM IS A COMPROMISE. WE DO EXPECT SOME THINNING OF THOSE
CLOUDS THIS AFTERNOON...THE RAP WAS WAY OVERDONE YESTERDAY. WE
INCREASED SKY COVER OVER THE NORTHERN AND EASTERN CWA
TODAY...ESPECIALLY THIS MORNING. WE KEPT THE FORECAST DRY TODAY
INTO TONIGHT...BUT WOULD NOT BE SURPRISED IF SOME FLURRIES
DEVELOPED. OVERALL...WE EXPECT HIGHS TODAY FROM 29F TO 35F.
TONIGHT...WITH PERSISTENT LOW LEVEL NORTHEAST FLOW WE EXPECT THE
CLOUDS TO EXPAND WEST AND SOUTH THROUGH MUCH OF THE CWA AND HAVE
MOST AREAS MOSTLY CLOUDY TONIGHT INTO SATURDAY. THE CLOUDS SHOULD
HOLD TEMPS UP TONIGHT...AND WE HAVE THEM FROM 8F TO 14F. SOME
POCKETS OF COLDER TEMPS WILL BE POSSIBLE IN ANY AREAS THAT SEE AN
EXTENDED PERIOD OF MOSTLY CLEAR SKIES...SINCE WINDS WILL BE LIGHT.
A SHORTWAVE WILL ROTATE THROUGH THE AREA ON SATURDAY...AND SHOULD
BE ENOUGH TO SET OFF SOME FLURRIES. WE HAVE SCATTERED FLURRIES
MAINLY OVER OUR MINNESOTA ZONES...INTO FAR NORTHWEST WISCONSIN.
HIGHS SHOULD REBOUND TO 30F TO 35F FOR MOST AREAS.
LONG TERM...SAT NIGHT THROUGH FRIDAY.
THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT
OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH
OVER THE ROCKIES THROUGH THE WEEKEND WITH A PERSISTENT NORTH TO
NORTHEAST BDRY LAYER FLOW. MODELS IN GOOD AGREEMENT THAT A VORT MAX
EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST ACROSS THE SRN
PLAINS THROUGH SUNDAY. MEANWHILE...LATEST MODEL RUNS ARE SUGGESTING A
SHORT WAVE BREAKS FREE FROM MAIN FLOW AND LIFTS INTO THE UPPER
PLAINS. THE 00Z RUNS OF THE ECM/NAM/GFS ALL SHOW THE SHORT WAVE
BECOMES A CLOSED H50 LOW IN THE VCNY OF MONTANA/WRN DAKOTAS BY
SUNDAY MORNING. ATTM...HAVE KEPT FCST DRY THROUGH THE WEEKEND AS THE
FORCING/PRECIP FROM THE WAVE IN THE DAKOTAS LOOKS TO REMAIN TO THE
WEST OF THE FA...WHILE THE SOUTHERN STREAM LOW STAYS WELL OFF TO THE
SOUTH. HOWEVER...RH FIELDS AND LATEST NAM BUFR SOUNDINGS CONTINUE TO
SHOW INCREASING LOW LEVEL MOISTURE SAT NIGHT/SUN...SO HAVE
INTRODUCED BROADBRUSH FLURRIES DURING THIS TIME. THE ONSHORE WINDS
MAY ALLOW FOR ADDITIONAL LIFT/ENHANCEMENT TO PRODUCE A FEW LIGHT SNOW
SHOWERS ALONG SOUTH SHORE OF LAKE SUPERIOR SUNDAY THROUGH EARLY NEXT
WEEK.
BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS
MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST.
LATEST RUNS OF THE ECM/GEM/GFS ARE ALL SUGGESTING A H50 CLOSED LOW
RETROGRADES ACROSS HUDSON BAY AND TRACKS INTO MANITOBA THROUGH
MONDAY. FROM HERE THERE ARE LARGE MODEL DIFFERENCES IN THE TRACK OF
THE VORT MAX AS THE ECM KEEPS THE LOW NEARLY STATIONARY OVER
MANITOBA...WHILE THE GFS DROPS THE LOW ACROSS THE DLH CWA THROUGH
MID-WEEK.
&&
.POINT TEMPS/POPS...
DLH 31 15 32 17 / 10 10 10 10
INL 30 10 32 15 / 10 10 10 10
BRD 32 13 33 18 / 0 10 10 10
HYR 33 8 35 16 / 0 10 10 10
ASX 31 11 32 17 / 10 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
506 PM CDT FRI MAR 22 2013
.DISCUSSION...
307 PM CDT
TONIGHT THROUGH SATURDAY...
ANTI-CYCLONIC FLOW WILL CONTINUE TO PROVIDE DRY WEATHER THROUGH
TONIGHT...HOWEVER WILL BEGIN TO LIFT NORTH SAT AHEAD OF A POTENT
WINTER WEATHER SYSTEM SET TO ARRIVE LATE SAT NIGHT. VISIBLE
IMAGERY THIS AFTERNOON CONTINUES TO DEPICT THE CHANNEL OF CIRRUS
AND MID-LVL CLOUDS SLIDING NORTHEAST FROM THE NORTHERN PLAINS
SOUTHEAST THROUGH CENTRAL TENNESSEE. ANOTHER CHANNEL OF CLOUDS WAS
SLOWLY DROPPING SOUTH ACROSS THE UPPER PENINSULA OF MI TO
NORTHEAST LOWER MI. SFC TEMPS HAVE WARMED THIS AFTERNOON ACROSS
NORTHERN IL INTO THE MID 30S ACROSS MANY AREAS...HOWEVER WITH THE
LIGHT FLOW AND WARMER SFC TEMPS INITIALLY ACROSS CHICAGO...A LAKE
BREEZE HAS FORMED AND SLOWLY PUSHING INLAND. THIS HAS RESULTED IN
SFC TEMPS ALONG THE IMMEDIATE SHORELINE COOLING. OVERNIGHT TONIGHT
SKIES SHOULD REMAIN RELATIVELY CLEAR...POSSIBLY JUST A THIN CIRRUS
DECK WILL SLIDE OVERHEAD. LCL HI-RES GUIDANCE HAS SUGGESTED AN
ARRIVAL OF A THIN STRATUS LAYER EARLY SAT MORNING ACROSS NORTHEAST
IL...WHICH COULD POSE SIGNIFICANT CHALLENGES WITH THE HIGH
FORECAST FOR SAT.
OVERNIGHT TEMPS WILL COOL INTO THE TEENS ACROSS THE REMAINING
SNOWPACK AREAS OF FAR NORTHERN/NORTHWEST IL...OTHERWISE TEMPS WILL
RADIATE INTO THE LOW/MID 20S. THE WARMEST AREAS MAY END UP BEING THE
AREAS ADJACENT TO LAKE MICHIGAN. WINDS WILL ALSO BE TURNING
NORTHEASTERLY OFF OF THE LAKE OVERNIGHT.
GUIDANCE CONTINUES TO FAVOR THE MID-LVL RIDGE AXIS PUSHING EAST OF
THE AREA SAT EVE...ALLOWING FOR ANOTHER DAY OF DRY WEATHER. ALTHOUGH
IT DOES APPEAR THAT WITH WINDS BECOMING NORTH/NORTHEAST...THE
CHANCES OF TEMPS WARMING FURTHER INTO THE UPR 30S TO LOW 40S LOOKS
MINIMAL. HAVE OPTED TO NUDGE TEMPS DOWN A COUPLE OF DEGREES INTO THE
MID/UPR 30S.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...
LATE SEASON WINTER STORM CONTINUES TO BE THE MAIN FOCUS FOR THE OHIO
VALLEY. AT THIS TIME THE ECMWF CONTINUES TO TAKE THE SYSTEM FURTHER
SOUTH...PULLING THE SNOW TOTALS FURTHER SOUTH INTO CENTRAL IL/IN FOR
THE ENTIRE EVENT. SREF PLUMES HAVE INDICATED THAT MANY LOCATIONS
ALONG AND SOUTH OF I-80 WILL SEE SEVERAL INCHES OF SNOWFALL FOR THE
EVENT...WITH A RANGE FROM 1 INCH TO POSSIBLE IN EXCESS OF 6 INCHES.
GUIDANCE CONTINUES TO SHOW CORRECTIONS ON THE PLACEMENT/INTENSITY OF
THIS SYSTEM...AS WELL AS THE FGEN LOCATION. THE 850MB LOW IS
CURRENTLY PROGGED TO SLIDE EAST FROM CENTRAL MO INTO SOUTHCENTRAL
IL/CENTRAL IN. THIS COULD PLACE THE BEST FGEN BAND ACROSS THE
SOUTHERN CWFA...MAINLY LIVINGSTON/FORD/IROQUOIS COUNTIES STRETCHING
EAST INTO NEWTON/JASPER/BENTON COUNTIES. WILL PROCEED TO POST A
WINTER STORM WATCH FOR THE THESE COUNTIES IN THE SOUTHERN CWFA.
ENSEMBLES HAVE CONTINUED TO SHOW SOME STRENGTHENING IN THE 850MB
EASTERLY U-WIND ANOMS SUN TO NEARLY 4 SIGMA...30-40KTS. ABUNDANT
MOISTURE WILL BE PICKED UP AHEAD OF THIS SYSTEM FROM THE WESTERN
GULF OF MEXICO...IN ADDITION THE ATMOSPHERE ACROSS CENTRAL IL/IN
DOES APPEAR TO BECOME UNSTABLE AT THE PEAK OF THE STORM. ADDING TO
THE POSSIBILITY OF THUNDER/LIGHTNING ACCOMPANYING THE SNOW. THIS
COULD EASILY ENHANCE THE SNOWFALL RATES IN THE 15-00Z SUN TIMEFRAME.
AT THIS TIME IT APPEARS THE BEST LOCATION FOR THIS WOULD OCCUR ALONG
THE FAR SOUTHERN SECTIONS OF FORD/IROQUOIS/LIVINGSTON COUNTIES SUN.
THE LARGEST CAVEAT IS THAT HIGH PRESSURE WILL BE LIFTING TO THE
NORTH OF THE REGION...WITH A TIGHTENING GRADIENT DEVELOPING ALONG
THE NORTHERN PERIPHERY OF THE SYSTEM. THIS SETUP WOULD MOST LIKELY
SHARPEN UP THE SNOW TOTALS FROM WHERE IT SNOWS TO SEVERAL
INCHES...GIVEN THE DRY NEAR SFC ENVIRONMENT. HOWEVER...COMPOUNDING
THIS IS THE FACT THAT THE POTENTIAL FOR LAKE EFFECT SNOW INCREASES
GIVEN HOW COLD THE ENVIRONMENT WILL BE. THERMAL DIFFERENTIALS FROM
THE LAKE SFC/850MB BECOMES FAVORABLE IN THE 12-15 DEG RANGE. SO HAVE
MAINTAINED THE FORMATION OF LAKE SNOW FOR FAR NORTHEAST IL SUN.
WITH THE THICKENING CLOUD COVER AND A COOL BREEZE FROM THE
NORTHEAST...TEMPS SUN MAY STRUGGLE TO WARM BEYOND THE LOW 30S.
CONFIDENCE IN TEMPERATURES...HIGH.
CONFIDENCE IN SNOWFALL...MEDIUM.
CONFIDENCE IN SNOW TIMING...MEDIUM.
MONDAY THROUGH THURSDAY...
500MB TROUGH AXIS CONTINUES TO PIVOT EAST TOWARDS THE EAST COAST
MON...WITH WEAK RIDGING BEGINNING TO FORM ACROSS THE PAC-NW. IT
APPEARS BEYOND MON THROUGH THE REMAINDER OF THE WEEKEND THE UPSTREAM
RIDGE REMAINS ACROSS THE PAC-NW POSSIBLY STRETCHING INTO THE
CANADIAN ROCKIES...WHICH COULD ALLOW FOR A CONTINUED NORTHWEST FLOW
ACROSS THE GREAT LAKES REGION FOR THE BULK OF THE EXTENDED. IN
ADDITION TO THIS GUIDANCE ALSO FAVORS A SLIGHTLY COOLER EXTENDED
FORECAST...HOWEVER DRY. GUIDANCE IS INDICATING WITH A HIGH LEVEL OF
CONFIDENCE THAT SFC RIDGING WILL INFLUENCE THE REGION FOR THE BULK
OF THE EXTENDED.
CONFIDENCE...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT
SATURDAY.
RATZER/IZZI
//DISCUSSION...UPDATED 18Z...
SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE
FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE
TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST
WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT
OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE
BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON.
CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH
EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT
NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND
SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR
OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT
LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE
REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED
ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS
THE SOUTHERN PLAINS.
OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE
POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI
AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON.
SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH
COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH
CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A
SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED
BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM
SYSTEM MOVES INTO THE LOWER OHIO VALLEY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING.
RATZER/IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT.
SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING
THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR
IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE
AFTERNOON AND NIGHT.
MONDAY...MVFR WITH A CHC OF SNOW SHOWERS.
TUESDAY...SLT CHC OF SNOW SHOWERS.
WEDNESDAY AND THURSDAY...MAINLY VFR.
MTF
&&
.MARINE...
225 PM CDT
A SURFACE RIDGE OF HIGH PRESSURE IS CURRENTLY DOMINATING ACROSS THE
WESTERN LAKES. THIS IS PRODUCING FAIRLY WEAK SURFACE FLOW. THE MAIN
CONCERNS DURING THE PERIOD WILL BE LATER THIS WEEKEND AND INTO EARLY
NEXT WEEK. A POTENT STORM SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD
FROM THE LOWER MISSISSIPPI VALLEY ACROSS OHIO VALLEY...AND THIS
SHOULD RESULT IN A PERIOD OF STRONGER NORTH-NORTHEASTERLY WINDS OVER
THE LAKE SUNDAY INTO MONDAY. IT CURRENTLY APPEARS THAT THE WINDS
WILL REALLY RAMP UP TO AROUND 30 KT OUT OF THE NORTHEAST ON SUNDAY
AS THE SURFACE LOW TRACKS ACROSS WESTERN KENTUCKY. AS THE LOW
CONTINUES EASTWARD ACROSS THE OHIO VALLEY SUNDAY NIGHT INTO MONDAY
THE WINDS WILL BECOME NORTHERLY. A PERIOD OF GALES IS POSSIBLE
DURING THIS PERIOD...ESPECIALLY ACROSS THE SOUTHERN END OF LAKE
MICHIGAN. THIS SYSTEM WILL LIKELY RESULT IN SMALL CRAFT CONDITIONS
FOR BOTH THE ILLINOIS AND INDIANA SHORES FROM EARLY SUNDAY THROUGH
TUESDAY.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WATCH...ILZ032-ILZ033-ILZ039...7 AM SUNDAY TO 7 AM
MONDAY.
IN...WINTER STORM WATCH...INZ010-INZ011-INZ019...7 AM SUNDAY TO 7 AM
MONDAY.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
336 PM CDT FRI MAR 22 2013
.DISCUSSION...
307 PM CDT
TONIGHT THROUGH SATURDAY...
ANTI-CYCLONIC FLOW WILL CONTINUE TO PROVIDE DRY WEATHER THROUGH
TONIGHT...HOWEVER WILL BEGIN TO LIFT NORTH SAT AHEAD OF A POTENT
WINTER WEATHER SYSTEM SET TO ARRIVE LATE SAT NIGHT. VISIBLE
IMAGERY THIS AFTERNOON CONTINUES TO DEPICT THE CHANNEL OF CIRRUS
AND MID-LVL CLOUDS SLIDING NORTHEAST FROM THE NORTHERN PLAINS
SOUTHEAST THROUGH CENTRAL TENNESSEE. ANOTHER CHANNEL OF CLOUDS WAS
SLOWLY DROPPING SOUTH ACROSS THE UPPER PENINSULA OF MI TO
NORTHEAST LOWER MI. SFC TEMPS HAVE WARMED THIS AFTERNOON ACROSS
NORTHERN IL INTO THE MID 30S ACROSS MANY AREAS...HOWEVER WITH THE
LIGHT FLOW AND WARMER SFC TEMPS INITIALLY ACROSS CHICAGO...A LAKE
BREEZE HAS FORMED AND SLOWLY PUSHING INLAND. THIS HAS RESULTED IN
SFC TEMPS ALONG THE IMMEDIATE SHORELINE COOLING. OVERNIGHT TONIGHT
SKIES SHOULD REMAIN RELATIVELY CLEAR...POSSIBLY JUST A THIN CIRRUS
DECK WILL SLIDE OVERHEAD. LCL HI-RES GUIDANCE HAS SUGGESTED AN
ARRIVAL OF A THIN STRATUS LAYER EARLY SAT MORNING ACROSS NORTHEAST
IL...WHICH COULD POSE SIGNIFICANT CHALLENGES WITH THE HIGH
FORECAST FOR SAT.
OVERNIGHT TEMPS WILL COOL INTO THE TEENS ACROSS THE REMAINING
SNOWPACK AREAS OF FAR NORTHERN/NORTHWEST IL...OTHERWISE TEMPS WILL
RADIATE INTO THE LOW/MID 20S. THE WARMEST AREAS MAY END UP BEING THE
AREAS ADJACENT TO LAKE MICHIGAN. WINDS WILL ALSO BE TURNING
NORTHEASTERLY OFF OF THE LAKE OVERNIGHT.
GUIDANCE CONTINUES TO FAVOR THE MID-LVL RIDGE AXIS PUSHING EAST OF
THE AREA SAT EVE...ALLOWING FOR ANOTHER DAY OF DRY WEATHER. ALTHOUGH
IT DOES APPEAR THAT WITH WINDS BECOMING NORTH/NORTHEAST...THE
CHANCES OF TEMPS WARMING FURTHER INTO THE UPR 30S TO LOW 40S LOOKS
MINIMAL. HAVE OPTED TO NUDGE TEMPS DOWN A COUPLE OF DEGREES INTO THE
MID/UPR 30S.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...
LATE SEASON WINTER STORM CONTINUES TO BE THE MAIN FOCUS FOR THE OHIO
VALLEY. AT THIS TIME THE ECMWF CONTINUES TO TAKE THE SYSTEM FURTHER
SOUTH...PULLING THE SNOW TOTALS FURTHER SOUTH INTO CENTRAL IL/IN FOR
THE ENTIRE EVENT. SREF PLUMES HAVE INDICATED THAT MANY LOCATIONS
ALONG AND SOUTH OF I-80 WILL SEE SEVERAL INCHES OF SNOWFALL FOR THE
EVENT...WITH A RANGE FROM 1 INCH TO POSSIBLE IN EXCESS OF 6 INCHES.
GUIDANCE CONTINUES TO SHOW CORRECTIONS ON THE PLACEMENT/INTENSITY OF
THIS SYSTEM...AS WELL AS THE FGEN LOCATION. THE 850MB LOW IS
CURRENTLY PROGGED TO SLIDE EAST FROM CENTRAL MO INTO SOUTHCENTRAL
IL/CENTRAL IN. THIS COULD PLACE THE BEST FGEN BAND ACROSS THE
SOUTHERN CWFA...MAINLY LIVINGSTON/FORD/IROQUOIS COUNTIES STRETCHING
EAST INTO NEWTON/JASPER/BENTON COUNTIES. WILL PROCEED TO POST A
WINTER STORM WATCH FOR THE THESE COUNTIES IN THE SOUTHERN CWFA.
ENSEMBLES HAVE CONTINUED TO SHOW SOME STRENGTHENING IN THE 850MB
EASTERLY U-WIND ANOMS SUN TO NEARLY 4 SIGMA...30-40KTS. ABUNDANT
MOISTURE WILL BE PICKED UP AHEAD OF THIS SYSTEM FROM THE WESTERN
GULF OF MEXICO...IN ADDITION THE ATMOSPHERE ACROSS CENTRAL IL/IN
DOES APPEAR TO BECOME UNSTABLE AT THE PEAK OF THE STORM. ADDING TO
THE POSSIBILITY OF THUNDER/LIGHTNING ACCOMPANYING THE SNOW. THIS
COULD EASILY ENHANCE THE SNOWFALL RATES IN THE 15-00Z SUN TIMEFRAME.
AT THIS TIME IT APPEARS THE BEST LOCATION FOR THIS WOULD OCCUR ALONG
THE FAR SOUTHERN SECTIONS OF FORD/IROQUOIS/LIVINGSTON COUNTIES SUN.
THE LARGEST CAVEAT IS THAT HIGH PRESSURE WILL BE LIFTING TO THE
NORTH OF THE REGION...WITH A TIGHTENING GRADIENT DEVELOPING ALONG
THE NORTHERN PERIPHERY OF THE SYSTEM. THIS SETUP WOULD MOST LIKELY
SHARPEN UP THE SNOW TOTALS FROM WHERE IT SNOWS TO SEVERAL
INCHES...GIVEN THE DRY NEAR SFC ENVIRONMENT. HOWEVER...COMPOUNDING
THIS IS THE FACT THAT THE POTENTIAL FOR LAKE EFFECT SNOW INCREASES
GIVEN HOW COLD THE ENVIRONMENT WILL BE. THERMAL DIFFERENTIALS FROM
THE LAKE SFC/850MB BECOMES FAVORABLE IN THE 12-15 DEG RANGE. SO HAVE
MAINTAINED THE FORMATION OF LAKE SNOW FOR FAR NORTHEAST IL SUN.
WITH THE THICKENING CLOUD COVER AND A COOL BREEZE FROM THE
NORTHEAST...TEMPS SUN MAY STRUGGLE TO WARM BEYOND THE LOW 30S.
CONFIDENCE IN TEMPERATURES...HIGH.
CONFIDENCE IN SNOWFALL...MEDIUM.
CONFIDENCE IN SNOW TIMING...MEDIUM.
MONDAY THROUGH THURSDAY...
500MB TROUGH AXIS CONTINUES TO PIVOT EAST TOWARDS THE EAST COAST
MON...WITH WEAK RIDGING BEGINNING TO FORM ACROSS THE PAC-NW. IT
APPEARS BEYOND MON THROUGH THE REMAINDER OF THE WEEKEND THE UPSTREAM
RIDGE REMAINS ACROSS THE PAC-NW POSSIBLY STRETCHING INTO THE
CANADIAN ROCKIES...WHICH COULD ALLOW FOR A CONTINUED NORTHWEST FLOW
ACROSS THE GREAT LAKES REGION FOR THE BULK OF THE EXTENDED. IN
ADDITION TO THIS GUIDANCE ALSO FAVORS A SLIGHTLY COOLER EXTENDED
FORECAST...HOWEVER DRY. GUIDANCE IS INDICATING WITH A HIGH LEVEL OF
CONFIDENCE THAT SFC RIDGING WILL INFLUENCE THE REGION FOR THE BULK
OF THE EXTENDED.
CONFIDENCE...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* WEAK LAKE BREEZE DEVELOPING LATE AFTERNOON WITH WINDS SHIFTING
TO THE NORTHEAST OR EAST-NORTHEAST...10 KTS OR LESS.
* POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT
SATURDAY.
RATZER
//DISCUSSION...UPDATED 18Z...
SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE
FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE
TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST
WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT
OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE
BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON.
CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH
EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT
NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND
SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR
OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT
LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE
REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED
ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS
THE SOUTHERN PLAINS.
OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE
POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI
AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON.
SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH
COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH
CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A
SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED
BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM
SYSTEM MOVES INTO THE LOWER OHIO VALLEY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE ON LAKE BREEZE TIMING.
* LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT.
SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING
THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR
IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE
AFTERNOON AND NIGHT.
MONDAY...MVFR WITH A CHC OF SNOW SHOWERS.
TUESDAY...SLT CHC OF SNOW SHOWERS.
WEDNESDAY AND THURSDAY...MAINLY VFR.
MTF
&&
.MARINE...
225 PM CDT
A SURFACE RIDGE OF HIGH PRESSURE IS CURRENTLY DOMINATING ACROSS THE
WESTERN LAKES. THIS IS PRODUCING FAIRLY WEAK SURFACE FLOW. THE MAIN
CONCERNS DURING THE PERIOD WILL BE LATER THIS WEEKEND AND INTO EARLY
NEXT WEEK. A POTENT STORM SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD
FROM THE LOWER MISSISSIPPI VALLEY ACROSS OHIO VALLEY...AND THIS
SHOULD RESULT IN A PERIOD OF STRONGER NORTH-NORTHEASTERLY WINDS OVER
THE LAKE SUNDAY INTO MONDAY. IT CURRENTLY APPEARS THAT THE WINDS
WILL REALLY RAMP UP TO AROUND 30 KT OUT OF THE NORTHEAST ON SUNDAY
AS THE SURFACE LOW TRACKS ACROSS WESTERN KENTUCKY. AS THE LOW
CONTINUES EASTWARD ACROSS THE OHIO VALLEY SUNDAY NIGHT INTO MONDAY
THE WINDS WILL BECOME NORTHERLY. A PERIOD OF GALES IS POSSIBLE
DURING THIS PERIOD...ESPECIALLY ACROSS THE SOUTHERN END OF LAKE
MICHIGAN. THIS SYSTEM WILL LIKELY RESULT IN SMALL CRAFT CONDITIONS
FOR BOTH THE ILLINOIS AND INDIANA SHORES FROM EARLY SUNDAY THROUGH
TUESDAY.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WATCH...ILZ032-ILZ033-ILZ039...7 AM SUNDAY TO 7 AM
MONDAY.
IN...WINTER STORM WATCH...INZ010-INZ011-INZ019...7 AM SUNDAY TO 7 AM
MONDAY.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
309 PM CDT FRI MAR 22 2013
.DISCUSSION...
307 PM CDT
TONIGHT THROUGH SATURDAY...
ANTI-CYCLONIC FLOW WILL CONTINUE TO PROVIDE DRY WEATHER THROUGH
TONIGHT...HOWEVER WILL BEGIN TO LIFT NORTH SAT AHEAD OF A POTENT
WINTER WEATHER SYSTEM SET TO ARRIVE LATE SAT NIGHT. VISIBLE
IMAGERY THIS AFTERNOON CONTINUES TO DEPICT THE CHANNEL OF CIRRUS
AND MID-LVL CLOUDS SLIDING NORTHEAST FROM THE NORTHERN PLAINS
SOUTHEAST THROUGH CENTRAL TENNESSEE. ANOTHER CHANNEL OF CLOUDS WAS
SLOWLY DROPPING SOUTH ACROSS THE UPPER PENINSULA OF MI TO
NORTHEAST LOWER MI. SFC TEMPS HAVE WARMED THIS AFTERNOON ACROSS
NORTHERN IL INTO THE MID 30S ACROSS MANY AREAS...HOWEVER WITH THE
LIGHT FLOW AND WARMER SFC TEMPS INITIALLY ACROSS CHICAGO...A LAKE
BREEZE HAS FORMED AND SLOWLY PUSHING INLAND. THIS HAS RESULTED IN
SFC TEMPS ALONG THE IMMEDIATE SHORELINE COOLING. OVERNIGHT TONIGHT
SKIES SHOULD REMAIN RELATIVELY CLEAR...POSSIBLY JUST A THIN CIRRUS
DECK WILL SLIDE OVERHEAD. LCL HI-RES GUIDANCE HAS SUGGESTED AN
ARRIVAL OF A THIN STRATUS LAYER EARLY SAT MORNING ACROSS NORTHEAST
IL...WHICH COULD POSE SIGNIFICANT CHALLENGES WITH THE HIGH
FORECAST FOR SAT.
OVERNIGHT TEMPS WILL COOL INTO THE TEENS ACROSS THE REMAINING
SNOWPACK AREAS OF FAR NORTHERN/NORTHWEST IL...OTHERWISE TEMPS WILL
RADIATE INTO THE LOW/MID 20S. THE WARMEST AREAS MAY END UP BEING THE
AREAS ADJACENT TO LAKE MICHIGAN. WINDS WILL ALSO BE TURNING
NORTHEASTERLY OFF OF THE LAKE OVERNIGHT.
GUIDANCE CONTINUES TO FAVOR THE MID-LVL RIDGE AXIS PUSHING EAST OF
THE AREA SAT EVE...ALLOWING FOR ANOTHER DAY OF DRY WEATHER. ALTHOUGH
IT DOES APPEAR THAT WITH WINDS BECOMING NORTH/NORTHEAST...THE
CHANCES OF TEMPS WARMING FURTHER INTO THE UPR 30S TO LOW 40S LOOKS
MINIMAL. HAVE OPTED TO NUDGE TEMPS DOWN A COUPLE OF DEGREES INTO THE
MID/UPR 30S.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...
LATE SEASON WINTER STORM CONTINUES TO BE THE MAIN FOCUS FOR THE OHIO
VALLEY. AT THIS TIME THE ECMWF CONTINUES TO TAKE THE SYSTEM FURTHER
SOUTH...PULLING THE SNOW TOTALS FURTHER SOUTH INTO CENTRAL IL/IN FOR
THE ENTIRE EVENT. SREF PLUMES HAVE INDICATED THAT MANY LOCATIONS
ALONG AND SOUTH OF I-80 WILL SEE SEVERAL INCHES OF SNOWFALL FOR THE
EVENT...WITH A RANGE FROM 1 INCH TO POSSIBLE IN EXCESS OF 6 INCHES.
GUIDANCE CONTINUES TO SHOW CORRECTIONS ON THE PLACEMENT/INTENSITY OF
THIS SYSTEM...AS WELL AS THE FGEN LOCATION. THE 850MB LOW IS
CURRENTLY PROGGED TO SLIDE EAST FROM CENTRAL MO INTO SOUTHCENTRAL
IL/CENTRAL IN. THIS COULD PLACE THE BEST FGEN BAND ACROSS THE
SOUTHERN CWFA...MAINLY LIVINGSTON/FORD/IROQUOIS COUNTIES STRETCHING
EAST INTO NEWTON/JASPER/BENTON COUNTIES. WILL PROCEED TO POST A
WINTER STORM WATCH FOR THE THESE COUNTIES IN THE SOUTHERN CWFA.
ENSEMBLES HAVE CONTINUED TO SHOW SOME STRENGTHENING IN THE 850MB
EASTERLY U-WIND ANOMS SUN TO NEARLY 4 SIGMA...30-40KTS. ABUNDANT
MOISTURE WILL BE PICKED UP AHEAD OF THIS SYSTEM FROM THE WESTERN
GULF OF MEXICO...IN ADDITION THE ATMOSPHERE ACROSS CENTRAL IL/IN
DOES APPEAR TO BECOME UNSTABLE AT THE PEAK OF THE STORM. ADDING TO
THE POSSIBILITY OF THUNDER/LIGHTNING ACCOMPANYING THE SNOW. THIS
COULD EASILY ENHANCE THE SNOWFALL RATES IN THE 15-00Z SUN TIMEFRAME.
AT THIS TIME IT APPEARS THE BEST LOCATION FOR THIS WOULD OCCUR ALONG
THE FAR SOUTHERN SECTIONS OF FORD/IROQUOIS/LIVINGSTON COUNTIES SUN.
THE LARGEST CAVEAT IS THAT HIGH PRESSURE WILL BE LIFTING TO THE
NORTH OF THE REGION...WITH A TIGHTENING GRADIENT DEVELOPING ALONG
THE NORTHERN PERIPHERY OF THE SYSTEM. THIS SETUP WOULD MOST LIKELY
SHARPEN UP THE SNOW TOTALS FROM WHERE IT SNOWS TO SEVERAL
INCHES...GIVEN THE DRY NEAR SFC ENVIRONMENT. HOWEVER...COMPOUNDING
THIS IS THE FACT THAT THE POTENTIAL FOR LAKE EFFECT SNOW INCREASES
GIVEN HOW COLD THE ENVIRONMENT WILL BE. THERMAL DIFFERENTIALS FROM
THE LAKE SFC/850MB BECOMES FAVORABLE IN THE 12-15 DEG RANGE. SO HAVE
MAINTAINED THE FORMATION OF LAKE SNOW FOR FAR NORTHEAST IL SUN.
WITH THE THICKENING CLOUD COVER AND A COOL BREEZE FROM THE
NORTHEAST...TEMPS SUN MAY STRUGGLE TO WARM BEYOND THE LOW 30S.
CONFIDENCE IN TEMPERATURES...HIGH.
CONFIDENCE IN SNOWFALL...MEDIUM.
CONFIDENCE IN SNOW TIMING...MEDIUM.
MONDAY THROUGH THURSDAY...
500MB TROUGH AXIS CONTINUES TO PIVOT EAST TOWARDS THE EAST COAST
MON...WITH WEAK RIDGING BEGINNING TO FORM ACROSS THE PAC-NW. IT
APPEARS BEYOND MON THROUGH THE REMAINDER OF THE WEEKEND THE UPSTREAM
RIDGE REMAINS ACROSS THE PAC-NW POSSIBLY STRETCHING INTO THE
CANADIAN ROCKIES...WHICH COULD ALLOW FOR A CONTINUED NORTHWEST FLOW
ACROSS THE GREAT LAKES REGION FOR THE BULK OF THE EXTENDED. IN
ADDITION TO THIS GUIDANCE ALSO FAVORS A SLIGHTLY COOLER EXTENDED
FORECAST...HOWEVER DRY. GUIDANCE IS INDICATING WITH A HIGH LEVEL OF
CONFIDENCE THAT SFC RIDGING WILL INFLUENCE THE REGION FOR THE BULK
OF THE EXTENDED.
CONFIDENCE...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* WEAK LAKE BREEZE DEVELOPING LATE AFTERNOON WITH WINDS SHIFTING
TO THE NORTHEAST OR EAST-NORTHEAST...10 KTS OR LESS.
* POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT
SATURDAY.
RATZER
//DISCUSSION...UPDATED 18Z...
SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE
FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE
TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST
WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT
OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE
BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON.
CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH
EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT
NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND
SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR
OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT
LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE
REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED
ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS
THE SOUTHERN PLAINS.
OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE
POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI
AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON.
SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH
COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH
CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A
SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED
BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM
SYSTEM MOVES INTO THE LOWER OHIO VALLEY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE ON LAKE BREEZE TIMING.
* LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT.
SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING
THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR
IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE
AFTERNOON AND NIGHT.
MONDAY...MVFR WITH A CHC OF SNOW SHOWERS.
TUESDAY...SLT CHC OF SNOW SHOWERS.
WEDNESDAY AND THURSDAY...MAINLY VFR.
MTF
&&
.MARINE...
225 PM CDT
A SURFACE RIDGE OF HIGH PRESSURE IS CURRENTLY DOMINATING ACROSS THE
WESTERN LAKES. THIS IS PRODUCING FAIRLY WEAK SURFACE FLOW. THE MAIN
CONCERNS DURING THE PERIOD WILL BE LATER THIS WEEKEND AND INTO EARLY
NEXT WEEK. A POTENT STORM SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD
FROM THE LOWER MISSISSIPPI VALLEY ACROSS OHIO VALLEY...AND THIS
SHOULD RESULT IN A PERIOD OF STRONGER NORTH-NORTHEASTERLY WINDS OVER
THE LAKE SUNDAY INTO MONDAY. IT CURRENTLY APPEARS THAT THE WINDS
WILL REALLY RAMP UP TO AROUND 30 KT OUT OF THE NORTHEAST ON SUNDAY
AS THE SURFACE LOW TRACKS ACROSS WESTERN KENTUCKY. AS THE LOW
CONTINUES EASTWARD ACROSS THE OHIO VALLEY SUNDAY NIGHT INTO MONDAY
THE WINDS WILL BECOME NORTHERLY. A PERIOD OF GALES IS POSSIBLE
DURING THIS PERIOD...ESPECIALLY ACROSS THE SOUTHERN END OF LAKE
MICHIGAN. THIS SYSTEM WILL LIKELY RESULT IN SMALL CRAFT CONDITIONS
FOR BOTH THE ILLINOIS AND INDIANA SHORES FROM EARLY SUNDAY THROUGH
TUESDAY.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
239 PM CDT FRI MAR 22 2013
.DISCUSSION...
524 AM CDT
POTENTIAL FOR SIGNIFICANT SNOWFALL SUNDAY AND SUNDAY
NIGHT...ESPECIALLY S OF I-80 AND NEAR THE IL AND IN LAKE SHORE.
ATTENTION FOCUSED ON POTENTIAL OF SPRING SNOW STORM TO AFFECT THE
LOCAL FORECAST AREA BEGINNING OVERNIGHT SATURDAY NIGHT ACROSS THE
SW HALF OF THE FA AND THEN ACROSS THE ENTIRE FA SUNDAY AND SUNDAY
NIGHT. ALSO POTENTIAL FOR LAKE ENHANCED SNOWFALL ALONG THE IL AND
IN SHORES DURING SUNDAY AND SUNDAY NIGHT AS STRONG COLD NE LOW
LEVEL FLOW BACKS TO OUT OF THE N WITH TIME AS THE SURFACE LOW OF
THE STORM SYSTEM PASSES S AND SE OF THE REGION...POTENTIALLY
CONTRIBUTING ENHANCED CONVECTIVE SNOWFALL TOO THE WIDESPREAD
SYSTEM SNOW.
THIS STORM HAS BEEN TOUGH TO NAIL DOWN AS MODELS HAVE BEEN
OFFERING VARIOUS SOLUTIONS TO THE PATH OF THE STORM ACROSS THE
CENTRAL U.S. OVER THE LAST SEVERAL RUNS. LATEST MODEL OUTPUT
SEEMS TO HAVE CONVERGED SIGNIFICANTLY OVER PAST 24 HOURS AND
CONTINUITY OF EACH MODEL FROM PREVIOUS MODEL RUN TO THE LATEST
RUN...WITH ONE EXCEPTION...LENDS CREDENCE AND MORE CONFIDENCE IN
A MORE SOUTHERLY TRACK OF THE UPPER LOW. A JET MAX CURRENTLY
DIVING SSE OVER NV AND NORTHERN CA IS TO TURN SE OVER THE DESERT
SW AND THE SOUTHERN ROCKIES TONIGHT AND SATURDAY MORNING THEN HEAD
E OVER THE SOUTHERN PLAINS SATURDAY AFTERNOON AND EVENING BEFORE
TURNING ENE OVERNIGHT CROSSING THE SOUTHERN MS VALLEY AND
REACHING THE TN VALLEY BY SUNDAY EVENING.
LOOP OF SATELLITE WATER VAPOR IMAGERY ALREADY REVEALS A
DEVELOPING UPPER LOW CIRCULATION OVER THE INTERIOR PACIFIC NW. IN
RESPONSE TO THE JET THIS LOW IS PROGGED TO STRENGHTEN AS IT CURVES
SE AND E OVER THE CENTRAL ROCKIES AND THE CENTRAL PLAINS DURING
SATURDAY AND THEN E OVER THE MID MS VALLEY. BESIDES THE OUTLIER
OPERATIONAL 00Z GFS...MODEL CONSENSUS INCLUDING GFS ENSEMBLE
MEMBERS...GFS ENSEMBLE MEAN...AND SREF MEAN IS FOR THE UPPER LOW
TO TRACK ACROSS SOUTHERN MO OR ALONG THE MO-AR BORDER TO THE
LOWER OH VALLEY DURING SUNDAY. WITH THIS SOUTHERN TRACK THE
ASSOCIATED 850HPA AND SURFACE LOWS ARE PROGGED TO MOVE E ACROSS
SOUTHERN MO SATURDAY NIGHT AND THEN TO THE FA LOWER OH VALLEY BY
18Z SUNDAY.
BEST FORCING FROM ISENTROPIC UPGLIDE AND FRONTOGENESIS IS PROGGED
TO STRETCH FROM NORTHERN MO ACROSS CENTRAL IL AND CENTRAL IN
DURING THE SATURDAY NIGHT TO SUNDAY NIGHT PERIOD. WHILE FEEL
FAIRLY CONFIDENT IN THE SOUTHERN TRACK OF THE SYSTEM A BIT MORE
NORTHERLY TRACK...WHILE A VERY MINOR SHIFT FOR A HEMISPHERIC
MODEL...WOULD BRING THE THREAT OF A HEAVY SPRING SNOWFALL TO THE
SOUTHERN HALF OF THE LOCAL FORECAST AREA. BASED ON LATEST GUIDANCE
HAVE A RANCE OF SNOWFALL FROM 1 INCH ALONG THE WI BORDER TO 6 TO 7
INCHES ACROSS FAR SOUTHERN LASALLE...SOUTHERN FORD...SOUTHERN
IROQUOIS AND BENTON COUNTIES WITH THE 3 INCH TOTAL GENERALLY ALONG
THE I-80 CORRIDOR.
A WILD CARD THROWN INTO THE MIX IS THE POTENTIAL FOR LAKE
EFFECT/ENHANCED SNOW TO OCCUR. DURING SUNDAY AND SUNDAY NIGHT THE
COLD AIR IN PLACE ACROSS CANADA...THE GREAT LAKES AND THE NE U.S.
WILL TRAVEL ACROSS LAKE MI ON NE TO NNE FLOW. FORECAST TEMPERATURE
PROFILES INDICATE A CLOUD DEPTH OVER THE LAKE OF 5 TO 7K FT WITH
TOPS 7-9K FT. EXPECT ENHANCED SNOWFALL NEAR THE IL AND IN SHORES
ESPECIALLY SUN AFTERNOON AND EVENING AS THE BACKING OF THE FLOW
DRAMATICALLY INCREASES THE FETCH OVER THE LAKE. THE LAKE EFFECT
COULD LOCALLY DOUBLE SNOW AMOUNTS ALONG THE IL SHORE AND TRIPP LE
THEM IN NW IN.
ONCE ANY LINGER SNOW OR LAKE EFFECT SNOW SHOWERS END MONDAY AFTER
AN UPPER TROUGH TRAILING W AND NW FROM THE UPPER LOW PROGGED TO BE
WEAKENING AS IT MOVES FROM THE UPPER OH VALLEY ACROSS THE
NORTHEASTERN U.S. THE REST OF THE WEAK LOOKS TO BE TRANQUIL
OUTSIDE OF A SLIGHT CHANCE OF LIGHT SNOW TUESDAY AS ANOTHER UPPER
TROUGH DROPS S FROM THE SOUTHERN GREAT LAKES.
WHILE THE AMPLITUDE OF THE UPPER PATTERN ACROSS THE CONUS
DECREASES WITH TIME DURING MID AND LATE WEEK TEMPERATURES ARE
EXPECTED TO MODERATE SLIGHTLY AND REMAIN WELL BELOW NORMAL FOR
LATE MARCH AS AN UPPER TROUGH REMAINS OVER EASTERN NOAM AND THE
WESTERLIES STAY WELL SOUTH.
TRS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* WEAK LAKE BREEZE DEVELOPING LATE AFTERNOON WITH WINDS SHIFTING
TO THE NORTHEAST OR EAST-NORTHEAST...10 KTS OR LESS.
* POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT
SATURDAY.
RATZER
//DISCUSSION...UPDATED 18Z...
SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE
FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE
TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST
WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT
OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE
BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON.
CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH
EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT
NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND
SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR
OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT
LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE
REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED
ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS
THE SOUTHERN PLAINS.
OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE
POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI
AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON.
SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH
COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH
CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A
SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED
BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM
SYSTEM MOVES INTO THE LOWER OHIO VALLEY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE ON LAKE BREEZE TIMING.
* LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT.
SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING
THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR
IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE
AFTERNOON AND NIGHT.
MONDAY...MVFR WITH A CHC OF SNOW SHOWERS.
TUESDAY...SLT CHC OF SNOW SHOWERS.
WEDNESDAY AND THURSDAY...MAINLY VFR.
MTF
&&
.MARINE...
225 PM CDT
A SURFACE RIDGE OF HIGH PRESSURE IS CURRENTLY DOMINATING ACROSS THE
WESTERN LAKES. THIS IS PRODUCING FAIRLY WEAK SURFACE FLOW. THE MAIN
CONCERNS DURING THE PERIOD WILL BE LATER THIS WEEKEND AND INTO EARLY
NEXT WEEK. A POTENT STORM SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD
FROM THE LOWER MISSISSIPPI VALLEY ACROSS OHIO VALLEY...AND THIS
SHOULD RESULT IN A PERIOD OF STRONGER NORTH-NORTHEASTERLY WINDS OVER
THE LAKE SUNDAY INTO MONDAY. IT CURRENTLY APPEARS THAT THE WINDS
WILL REALLY RAMP UP TO AROUND 30 KT OUT OF THE NORTHEAST ON SUNDAY
AS THE SURFACE LOW TRACKS ACROSS WESTERN KENTUCKY. AS THE LOW
CONTINUES EASTWARD ACROSS THE OHIO VALLEY SUNDAY NIGHT INTO MONDAY
THE WINDS WILL BECOME NORTHERLY. A PERIOD OF GALES IS POSSIBLE
DURING THIS PERIOD...ESPECIALLY ACROSS THE SOUTHERN END OF LAKE
MICHIGAN. THIS SYSTEM WILL LIKELY RESULT IN SMALL CRAFT CONDITIONS
FOR BOTH THE ILLINOIS AND INDIANA SHORES FROM EARLY SUNDAY THROUGH
TUESDAY.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
225 PM CDT FRI MAR 22 2013
.DISCUSSION...
524 AM CDT
POTENTIAL FOR SIGNIFICANT SNOWFALL SUNDAY AND SUNDAY
NIGHT...ESPECIALLY S OF I-80 AND NEAR THE IL AND IN LAKE SHORE.
ATTENTION FOCUSED ON POTENTIAL OF SPRING SNOW STORM TO AFFECT THE
LOCAL FORECAST AREA BEGINNING OVERNIGHT SATURDAY NIGHT ACROSS THE
SW HALF OF THE FA AND THEN ACROSS THE ENTIRE FA SUNDAY AND SUNDAY
NIGHT. ALSO POTENTIAL FOR LAKE ENHANCED SNOWFALL ALONG THE IL AND
IN SHORES DURING SUNDAY AND SUNDAY NIGHT AS STRONG COLD NE LOW
LEVEL FLOW BACKS TO OUT OF THE N WITH TIME AS THE SURFACE LOW OF
THE STORM SYSTEM PASSES S AND SE OF THE REGION...POTENTIALLY
CONTRIBUTING ENHANCED CONVECTIVE SNOWFALL TOO THE WIDESPREAD
SYSTEM SNOW.
THIS STORM HAS BEEN TOUGH TO NAIL DOWN AS MODELS HAVE BEEN
OFFERING VARIOUS SOLUTIONS TO THE PATH OF THE STORM ACROSS THE
CENTRAL U.S. OVER THE LAST SEVERAL RUNS. LATEST MODEL OUTPUT
SEEMS TO HAVE CONVERGED SIGNIFICANTLY OVER PAST 24 HOURS AND
CONTINUITY OF EACH MODEL FROM PREVIOUS MODEL RUN TO THE LATEST
RUN...WITH ONE EXCEPTION...LENDS CREDENCE AND MORE CONFIDENCE IN
A MORE SOUTHERLY TRACK OF THE UPPER LOW. A JET MAX CURRENTLY
DIVING SSE OVER NV AND NORTHERN CA IS TO TURN SE OVER THE DESERT
SW AND THE SOUTHERN ROCKIES TONIGHT AND SATURDAY MORNING THEN HEAD
E OVER THE SOUTHERN PLAINS SATURDAY AFTERNOON AND EVENING BEFORE
TURNING ENE OVERNIGHT CROSSING THE SOUTHERN MS VALLEY AND
REACHING THE TN VALLEY BY SUNDAY EVENING.
LOOP OF SATELLITE WATER VAPOR IMAGERY ALREADY REVEALS A
DEVELOPING UPPER LOW CIRCULATION OVER THE INTERIOR PACIFIC NW. IN
RESPONSE TO THE JET THIS LOW IS PROGGED TO STRENGHTEN AS IT CURVES
SE AND E OVER THE CENTRAL ROCKIES AND THE CENTRAL PLAINS DURING
SATURDAY AND THEN E OVER THE MID MS VALLEY. BESIDES THE OUTLIER
OPERATIONAL 00Z GFS...MODEL CONSENSUS INCLUDING GFS ENSEMBLE
MEMBERS...GFS ENSEMBLE MEAN...AND SREF MEAN IS FOR THE UPPER LOW
TO TRACK ACROSS SOUTHERN MO OR ALONG THE MO-AR BORDER TO THE
LOWER OH VALLEY DURING SUNDAY. WITH THIS SOUTHERN TRACK THE
ASSOCIATED 850HPA AND SURFACE LOWS ARE PROGGED TO MOVE E ACROSS
SOUTHERN MO SATURDAY NIGHT AND THEN TO THE FA LOWER OH VALLEY BY
18Z SUNDAY.
BEST FORCING FROM ISENTROPIC UPGLIDE AND FRONTOGENESIS IS PROGGED
TO STRETCH FROM NORTHERN MO ACROSS CENTRAL IL AND CENTRAL IN
DURING THE SATURDAY NIGHT TO SUNDAY NIGHT PERIOD. WHILE FEEL
FAIRLY CONFIDENT IN THE SOUTHERN TRACK OF THE SYSTEM A BIT MORE
NORTHERLY TRACK...WHILE A VERY MINOR SHIFT FOR A HEMISPHERIC
MODEL...WOULD BRING THE THREAT OF A HEAVY SPRING SNOWFALL TO THE
SOUTHERN HALF OF THE LOCAL FORECAST AREA. BASED ON LATEST GUIDANCE
HAVE A RANCE OF SNOWFALL FROM 1 INCH ALONG THE WI BORDER TO 6 TO 7
INCHES ACROSS FAR SOUTHERN LASALLE...SOUTHERN FORD...SOUTHERN
IROQUOIS AND BENTON COUNTIES WITH THE 3 INCH TOTAL GENERALLY ALONG
THE I-80 CORRIDOR.
A WILD CARD THROWN INTO THE MIX IS THE POTENTIAL FOR LAKE
EFFECT/ENHANCED SNOW TO OCCUR. DURING SUNDAY AND SUNDAY NIGHT THE
COLD AIR IN PLACE ACROSS CANADA...THE GREAT LAKES AND THE NE U.S.
WILL TRAVEL ACROSS LAKE MI ON NE TO NNE FLOW. FORECAST TEMPERATURE
PROFILES INDICATE A CLOUD DEPTH OVER THE LAKE OF 5 TO 7K FT WITH
TOPS 7-9K FT. EXPECT ENHANCED SNOWFALL NEAR THE IL AND IN SHORES
ESPECIALLY SUN AFTERNOON AND EVENING AS THE BACKING OF THE FLOW
DRAMATICALLY INCREASES THE FETCH OVER THE LAKE. THE LAKE EFFECT
COULD LOCALLY DOUBLE SNOW AMOUNTS ALONG THE IL SHORE AND TRIPP LE
THEM IN NW IN.
ONCE ANY LINGER SNOW OR LAKE EFFECT SNOW SHOWERS END MONDAY AFTER
AN UPPER TROUGH TRAILING W AND NW FROM THE UPPER LOW PROGGED TO BE
WEAKENING AS IT MOVES FROM THE UPPER OH VALLEY ACROSS THE
NORTHEASTERN U.S. THE REST OF THE WEAK LOOKS TO BE TRANQUIL
OUTSIDE OF A SLIGHT CHANCE OF LIGHT SNOW TUESDAY AS ANOTHER UPPER
TROUGH DROPS S FROM THE SOUTHERN GREAT LAKES.
WHILE THE AMPLITUDE OF THE UPPER PATTERN ACROSS THE CONUS
DECREASES WITH TIME DURING MID AND LATE WEEK TEMPERATURES ARE
EXPECTED TO MODERATE SLIGHTLY AND REMAIN WELL BELOW NORMAL FOR
LATE MARCH AS AN UPPER TROUGH REMAINS OVER EASTERN NOAM AND THE
WESTERLIES STAY WELL SOUTH.
TRS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* WEAK LAKE BREEZE DEVELOPING LATE AFTERNOON WITH WINDS SHIFTING
TO THE NORTHEAST OR EAST-NORTHEAST...10 KTS OR LESS.
* POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT
SATURDAY.
RATZER
//DISCUSSION...UPDATED 18Z...
SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE
FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE
TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST
WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT
OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE
BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON.
CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH
EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT
NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND
SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR
OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT
LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE
REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED
ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS
THE SOUTHERN PLAINS.
OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE
POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI
AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON.
SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH
COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH
CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A
SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED
BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM
SYSTEM MOVES INTO THE LOWER OHIO VALLEY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM-LOW CONFIDENCE ON LAKE BREEZE TIMING.
* LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT.
SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING
THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR
IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE
AFTERNOON AND NIGHT.
MONDAY...MVFR WITH A CHC OF SNOW SHOWERS.
TUESDAY...SLT CHC OF SNOW SHOWERS.
WEDNESDAY AND THURSDAY...MAINLY VFR.
MTF
&&
.MARINE...
225 PM CDT
A SURFACE RIDGE OF HIGH PRESSURE IS CURRENTLY DOMINATING ACROSS THE
WESTERN LAKES. THIS IS PRODUCING FAIRLY WEAK SURFACE FLOW. THE MAIN
CONCERNS DURING THE PERIOD WILL BE LATER THIS WEEKEND AND INTO EARLY
NEXT WEEK. A POTENT STORM SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD
FROM THE LOWER MISSISSIPPI VALLEY ACROSS OHIO VALLEY...AND THIS
SHOULD RESULT IN A PERIOD OF STRONGER NORTH-NORTHEASTERLY WINDS OVER
THE LAKE SUNDAY INTO MONDAY. IT CURRENTLY APPEARS THAT THE WINDS
WILL REALLY RAMP UP TO AROUND 30 KT OUT OF THE NORTHEAST ON SUNDAY
AS THE SURFACE LOW TRACKS ACROSS WESTERN KENTUCKY. AS THE LOW
CONTINUES EASTWARD ACROSS THE OHIO VALLEY SUNDAY NIGHT INTO MONDAY
THE WINDS WILL BECOME NORTHERLY. A PERIOD OF GALES IS POSSIBLE
DURING THIS PERIOD...ESPECIALLY ACROSS THE SOUTHERN END OF LAKE
MICHIGAN. THIS SYSTEM WILL LIKELY RESULT IN SMALL CRAFT CONDITIONS
FOR BOTH THE ILLINOIS AND INDIANA SHORES FROM EARLY SUNDAY THROUGH
TUESDAY.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1251 PM CDT FRI MAR 22 2013
.DISCUSSION...
524 AM CDT
POTENTIAL FOR SIGNIFICANT SNOWFALL SUNDAY AND SUNDAY
NIGHT...ESPECIALLY S OF I-80 AND NEAR THE IL AND IN LAKE SHORE.
ATTENTION FOCUSED ON POTENTIAL OF SPRING SNOW STORM TO AFFECT THE
LOCAL FORECAST AREA BEGINNING OVERNIGHT SATURDAY NIGHT ACROSS THE
SW HALF OF THE FA AND THEN ACROSS THE ENTIRE FA SUNDAY AND SUNDAY
NIGHT. ALSO POTENTIAL FOR LAKE ENHANCED SNOWFALL ALONG THE IL AND
IN SHORES DURING SUNDAY AND SUNDAY NIGHT AS STRONG COLD NE LOW
LEVEL FLOW BACKS TO OUT OF THE N WITH TIME AS THE SURFACE LOW OF
THE STORM SYSTEM PASSES S AND SE OF THE REGION...POTENTIALLY
CONTRIBUTING ENHANCED CONVECTIVE SNOWFALL TOO THE WIDESPREAD
SYSTEM SNOW.
THIS STORM HAS BEEN TOUGH TO NAIL DOWN AS MODELS HAVE BEEN
OFFERING VARIOUS SOLUTIONS TO THE PATH OF THE STORM ACROSS THE
CENTRAL U.S. OVER THE LAST SEVERAL RUNS. LATEST MODEL OUTPUT
SEEMS TO HAVE CONVERGED SIGNIFICANTLY OVER PAST 24 HOURS AND
CONTINUITY OF EACH MODEL FROM PREVIOUS MODEL RUN TO THE LATEST
RUN...WITH ONE EXCEPTION...LENDS CREDENCE AND MORE CONFIDENCE IN
A MORE SOUTHERLY TRACK OF THE UPPER LOW. A JET MAX CURRENTLY
DIVING SSE OVER NV AND NORTHERN CA IS TO TURN SE OVER THE DESERT
SW AND THE SOUTHERN ROCKIES TONIGHT AND SATURDAY MORNING THEN HEAD
E OVER THE SOUTHERN PLAINS SATURDAY AFTERNOON AND EVENING BEFORE
TURNING ENE OVERNIGHT CROSSING THE SOUTHERN MS VALLEY AND
REACHING THE TN VALLEY BY SUNDAY EVENING.
LOOP OF SATELLITE WATER VAPOR IMAGERY ALREADY REVEALS A
DEVELOPING UPPER LOW CIRCULATION OVER THE INTERIOR PACIFIC NW. IN
RESPONSE TO THE JET THIS LOW IS PROGGED TO STRENGHTEN AS IT CURVES
SE AND E OVER THE CENTRAL ROCKIES AND THE CENTRAL PLAINS DURING
SATURDAY AND THEN E OVER THE MID MS VALLEY. BESIDES THE OUTLIER
OPERATIONAL 00Z GFS...MODEL CONSENSUS INCLUDING GFS ENSEMBLE
MEMBERS...GFS ENSEMBLE MEAN...AND SREF MEAN IS FOR THE UPPER LOW
TO TRACK ACROSS SOUTHERN MO OR ALONG THE MO-AR BORDER TO THE
LOWER OH VALLEY DURING SUNDAY. WITH THIS SOUTHERN TRACK THE
ASSOCIATED 850HPA AND SURFACE LOWS ARE PROGGED TO MOVE E ACROSS
SOUTHERN MO SATURDAY NIGHT AND THEN TO THE FA LOWER OH VALLEY BY
18Z SUNDAY.
BEST FORCING FROM ISENTROPIC UPGLIDE AND FRONTOGENESIS IS PROGGED
TO STRETCH FROM NORTHERN MO ACROSS CENTRAL IL AND CENTRAL IN
DURING THE SATURDAY NIGHT TO SUNDAY NIGHT PERIOD. WHILE FEEL
FAIRLY CONFIDENT IN THE SOUTHERN TRACK OF THE SYSTEM A BIT MORE
NORTHERLY TRACK...WHILE A VERY MINOR SHIFT FOR A HEMISPHERIC
MODEL...WOULD BRING THE THREAT OF A HEAVY SPRING SNOWFALL TO THE
SOUTHERN HALF OF THE LOCAL FORECAST AREA. BASED ON LATEST GUIDANCE
HAVE A RANCE OF SNOWFALL FROM 1 INCH ALONG THE WI BORDER TO 6 TO 7
INCHES ACROSS FAR SOUTHERN LASALLE...SOUTHERN FORD...SOUTHERN
IROQUOIS AND BENTON COUNTIES WITH THE 3 INCH TOTAL GENERALLY ALONG
THE I-80 CORRIDOR.
A WILD CARD THROWN INTO THE MIX IS THE POTENTIAL FOR LAKE
EFFECT/ENHANCED SNOW TO OCCUR. DURING SUNDAY AND SUNDAY NIGHT THE
COLD AIR IN PLACE ACROSS CANADA...THE GREAT LAKES AND THE NE U.S.
WILL TRAVEL ACROSS LAKE MI ON NE TO NNE FLOW. FORECAST TEMPERATURE
PROFILES INDICATE A CLOUD DEPTH OVER THE LAKE OF 5 TO 7K FT WITH
TOPS 7-9K FT. EXPECT ENHANCED SNOWFALL NEAR THE IL AND IN SHORES
ESPECIALLY SUN AFTERNOON AND EVENING AS THE BACKING OF THE FLOW
DRAMATICALLY INCREASES THE FETCH OVER THE LAKE. THE LAKE EFFECT
COULD LOCALLY DOUBLE SNOW AMOUNTS ALONG THE IL SHORE AND TRIPP LE
THEM IN NW IN.
ONCE ANY LINGER SNOW OR LAKE EFFECT SNOW SHOWERS END MONDAY AFTER
AN UPPER TROUGH TRAILING W AND NW FROM THE UPPER LOW PROGGED TO BE
WEAKENING AS IT MOVES FROM THE UPPER OH VALLEY ACROSS THE
NORTHEASTERN U.S. THE REST OF THE WEAK LOOKS TO BE TRANQUIL
OUTSIDE OF A SLIGHT CHANCE OF LIGHT SNOW TUESDAY AS ANOTHER UPPER
TROUGH DROPS S FROM THE SOUTHERN GREAT LAKES.
WHILE THE AMPLITUDE OF THE UPPER PATTERN ACROSS THE CONUS
DECREASES WITH TIME DURING MID AND LATE WEEK TEMPERATURES ARE
EXPECTED TO MODERATE SLIGHTLY AND REMAIN WELL BELOW NORMAL FOR
LATE MARCH AS AN UPPER TROUGH REMAINS OVER EASTERN NOAM AND THE
WESTERLIES STAY WELL SOUTH.
TRS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* WEAK LAKE BREEZE DEVELOPING LATE AFTERNOON WITH WINDS SHIFTING
TO THE NORTHEAST OR EAST-NORTHEAST...10 KTS OR LESS.
* POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT
SATURDAY.
RATZER
//DISCUSSION...UPDATED 18Z...
SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE
FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE
TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST
WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT
OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE
BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON.
CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH
EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT
NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND
SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR
OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT
LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE
REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED
ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS
THE SOUTHERN PLAINS.
OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE
POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI
AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON.
SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH
COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH
CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A
SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED
BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM
SYSTEM MOVES INTO THE LOWER OHIO VALLEY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM-LOW CONFIDENCE ON LAKE BREEZE TIMING.
* LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT.
SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING
THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR
IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE
AFTERNOON AND NIGHT.
MONDAY...MVFR WITH A CHC OF SNOW SHOWERS.
TUESDAY...SLT CHC OF SNOW SHOWERS.
WEDNESDAY AND THURSDAY...MAINLY VFR.
MTF
&&
.MARINE...
159 AM CDT
PERSISTENT LOW PRESSURE OVER SOUTHERN QUEBEC WILL BEGIN TO FINALLY
MOVE EAST LATER TODAY INTO TONIGHT EASING WIND SPEEDS ACROSS THE
NORTHERN PART OF THE LAKE. THIS SYSTEM DEPARTURE WILL ALLOW FOR THE
HIGH PRESSURE OVER THE MISSISSIPPI RIVER VALLEY TO SHIFT EAST OVER
LAKE MI INTO THE DAY SATURDAY. THE MOST PRONOUNCED SYSTEM IMPACTS
FOR THE LAKE WILL COME LATER SUNDAY...SUNDAY NIGHT...INTO THE DAY
MONDAY AS LOW PRESSURE MOVES FROM THE OZARKS REGION UP THE OHIO
RIVER VALLEY. SUCH A PATH WILL TIGHTEN THE PRESSURE GRADIENT ACROSS
LAKE MI...ESPECIALLY THE SOUTH. WINDS TO 30 KT LOOK VERY LIKELY OVER
THE SOUTHERN HALF INCLUDING NEARSHORE AREAS ON THE SOUTH...WITH GALE
FORCE WINDS POSSIBLE DEPENDING ON SYSTEM STRENGTH AND PRECISE PATH.
CIPS ANALOG GUIDANCE FOR SIMILAR REGIME MATCHES INDICATE A 50
PERCENT CHANCE OF WIND GUSTS EXCEEDING 30 KT ON NEARBY LAND AREAS
FOR THIS TIME...SO OVER WATER THE LIKELIHOOD IS HIGHER. SO BEYOND
THIS SYSTEM...GRADUALLY DIMINISHING NORTHERLY FLOW WILL CONTINUE FOR
A WHILE WITH PERSISTENT RIDGING BUILDING ONCE AGAIN OVER THE
MISSISSIPPI RIVER VALLEY.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
347 PM CDT FRI MAR 22 2013
.DISCUSSION...
20Z WATER VAPOR IMAGERY SHOWS A ELONGATED TROUGH FROM WESTERN
CANADA INTO THE NORTHERN ROCKIES WITH ENERGY DIGGING INTO ITS
BASE. AT THE SURFACE WEAK RIDGING REMAINS OVER THE NORTHERN AND
CENTRAL PLAINS WITH A COOL EASTERLY WIND.
FOR TONIGHT...LARGE SCALE FORCING FOR PRECIP LOOKS TO REMAIN TO THE
WEST ACROSS THE ROCKIES...SO THINK CHANCES FOR MEASURABLE PRECIP ARE
FAIRLY LOW. THE NAM AND RAP ARE SHOWING SOME WEAK ISENTROPIC ACCENT
DEVELOPING ON THE 280K SURFACE...SUGGESTING THERE COULD AGAIN BE
SOME PATCHY FREEZING DRIZZLE AFTER MIDNIGHT. BECAUSE OF THIS HAVE
INSERTED A SLIGHT CHANCE FOR FREEZING DRIZZLE. THINK THAT LOWS
TONIGHT SHOULD BE PRETTY SIMILAR TO THE LAST COUPLE NIGHTS GIVEN
OVERCAST SKIES AND LITTLE CHANGE TO THE AIRMASS.
FOR SATURDAY THROUGH SUNDAY...THE MAIN QUESTION IS WHETHER TO
UPGRADE TO A WARNING OR MAINTAIN THE WATCH. MODELS HAVE BEEN
CONSISTENT IN AMPLIFYING A SHORTWAVE AND MOVING IT ACROSS THE
FORECAST AREA. WITH VERY GOOD LARGE SCALE FORCING FROM THE PV
ANOMALY AND Q VECTOR CONVERGENCE...PRECIP IS EXPECTED TO BECOME
WIDESPREAD ACROSS WESTERN KS SATURDAY MORNING AND SPREAD EAST INTO
EASTERN KS BY THE AFTERNOON. THEREFORE POPS HAVE BEEN INCREASED FOR
THE FORECAST AREA SATURDAY AFTERNOON AND SATURDAY NIGHT. THE NAM AND
GFS FORECAST SOUNDINGS HAVE TRENDED WARMER WITH THE BOUNDARY LAYER
SATURDAY WITH SURFACE TEMPS IN THE UPPER 30S THROUGH THE AFTERNOON
ACROSS EAST CENTRAL KS. BECAUSE OF THIS HAVE MOVED THE RAIN/SNOW
LINE BACK NORTHWEST EXPECTING AREAS ALONG AND SOUTH OF THE TURNPIKE
TO SEE MAINLY RAIN THROUGH THE BULK OF THE DAY SATURDAY. ACROSS
NORTH CENTRAL KS...TEMPS LOOK COLD ENOUGH FOR PRECIP TO BE ALL SNOW.
AS THE UPPER WAVE PASSES TO THE EAST EARLY SATURDAY EVENING...THE
COLD AIR SHOULD FILL IN WITH PRECIP CHANGING TO SNOW DURING THE
EVENING. THERE IS SOME UNCERTAINTY IN PRECIP TYPE ACROSS EAST
CENTRAL KS FOR SATURDAY EVENING BECAUSE MODELS SHOW MID LEVEL DRY
AIR LIFTING INTO THE AREA AND DRYING OUT THE DENDRITIC GROWTH ZONE.
WITH NO ICE IN THE CLOUD...THERE COULD BE SIMPLY RAIN FALLING WITH
TEMPS IN THE MID 30S. WITH RAIN EXPECTED INITIALLY SATURDAY AND THE
POTENTIAL FOR A MIX OF PRECIP SATURDAY EVENING...HAVE KNOCKED DOWN
SNOW AMOUNTS ACROSS EAST CENTRAL KS WITH MAYBE AROUND 4 INCHES
POSSIBLE BY SUNDAY AFTERNOON. OTHERWISE IT IS NOT CLEAR WHETHER
SNOWFALL RATES WILL BE ENHANCED BY MESOSCALE FORCING OR IF IT WILL
BE DRIVEN ALL BY SYNOPTIC FORCING. THERE DOES APPEAR TO BE SOME
UPRIGHT INSTABILITY ON SATURDAY WHICH COULD INCREASE SNOWFALL RATES.
AND THE NAM HINTS AT A WEAK TROWAL SATURDAY NIGHT. HOWEVER IT ONLY
REALLY SHOWS UP AROUND 600 MB AND IS NOT VERY DEEP. CONSIDERING THE
SURFACE LOW COULD END UP OVER TN OR MS BY 12Z SUNDAY...AM NOT SURE
THE WARM CONVEYOR BELT WOULD WRAP ALL THE WAY BACK INTO EASTERN KS.
PERHAPS THE ENHANCED QPF FROM THE NAM IS A FUNCTION OF THE UPPER
LEVEL DEFORMATION FROM THE WAVE PROPAGATING EAST. SO FOR FAR
NORTHEAST AND NORTH CENTRAL KS...THE FORECAST IS STILL CALLING FOR
AROUND 5 TO 7 INCHES. HAVE DECIDED TO UPGRADE AREAS WEST OF MHK TO A
WARNING SINCE THEY SHOULD BEGIN TO BE IMPACTED BY THE STORM BY NOON
TOMORROW. SINCE PRECIP MAY END UP BEING MORE RAIN IN EAST CENTRAL KS
AND THE SNOW COULD HOLD OFF UNTIL SATURDAY EVENING...WILL KEEP THE
WATCH GOING FOR AREAS EAST OF MHK AND LET LATER SHIFTS HAVE A LOOK
AT THE NEWER GUIDANCE.
WITH MODELS ADVECTING A LITTLE MORE WARM AIR INTO EASTERN KS...HAVE
BUMPED HIGHS UP TO AROUND 40 IN THE EAST WITH HIGHS NEAR THE
FREEZING MARK ACROSS NORTH CENTRAL KS. LOWS SUNDAY MORNING SHOULD
FALL INTO THE 20S AS NORTHWEST WINDS INCREASE AND BRING COLDER AIR
SOUTH. CLOUD COVER AND BREEZY NORTHWEST WINDS SHOULD KEEP TEMPS FROM
WARMING MUCH ON SUNDAY...SO HIGHS ARE FORECAST TO BE IN THE LOWER TO
MID 30S.
WOLTERS
SUNDAY NIGHT THROUGH FRIDAY...
SECONDARY UPPER TROF SWINGS THROUGH LATE SUNDAY NIGHT AND MONDAY
WITH LIMITED FORCING AND ONLY SHALLOW MOISTURE SO WILL KEEP DRY
FORECAST GOING. NORTHWEST WINDS PERSIST WITH TEMPS OVER THE FRESH
SNOW NOT WARMING MUCH.
SURFACE RIDGE AXIS TAKES RESIDENCE MONDAY NIGHT INTO TUESDAY AS
ZONAL FLOW BEGINS TO TAKE HOLD OF THE SOUTHWESTERN THIRD OF THE
CONUS. SOUTH WINDS KICK IN FOR AT LEAST THE BULK OF THE AREA
WEDNESDAY FOR A MORE SIGNIFICANT WARM-UP...THOUGH MODELS DIVERGE
SOMEWHAT WITH SHORTWAVES COMING SOUTHEAST ACROSS THE NORTHERN PLAINS
AND GREAT LAKES...WHICH COULD LEAVE A MODIFIED BOUNDARY OVER THE
CENTRAL PLAINS. INCREASING LOW LEVEL MOISTURE VIA THE SOUTH WINDS
COMBINED WITH THE CONVERGENCE COULD BE ENOUGH FOR SOME CHANCE FOR
MAINLY RAIN FOR THE LATTER PERIODS. THOUGH CONFIDENCE IS NOT HIGH
GIVEN EASTERLY LOW LEVEL FLOW POTENTIAL...WILL BRING TEMPS UP TO
NEAR LATE MARCH NORMALS.
65
&&
.AVIATION...
IFR CONDITIONS SHOULD CONTINUE THROUGH THE EARLY AFTERNOON HOURS.
THE STRATUS DECK IS BEGINNING TO BREAK UP ACROSS CENTRAL KANSAS
THEREFORE MVFR CONDITIONS ARE EXPECTED AROUND 20Z. THERE MAY BE A
BRIEF PERIOD OF VFR CONDITIONS THIS EVENING BEFORE THE MVFR
CONDITIONS RETURN AGAIN AROUND 07Z. DRIZZLE MAY ALSO DEVELOP
OVERNIGHT AS SOUNDINGS SHOW WEAK LIFT IN A SATURATED LOW LEVEL
LAYER. THE MORE IMPRESSIVE LIFT AND COLUMN SATURATION ASSOCIATED
WITH THE MAIN STORM SYSTEM WILL BEGIN TO EFFECT THE AREA AROUND
15Z. ALTHOUGH CONFIDENCE IN THE START TIME OF PRECIP IS LOW.
THEREFORE LATER SHIFTS WILL MONITOR THE SITUATION AND CONTINUE
UPDATES.
SANDERS
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY
MORNING FOR KSZ011-012-023-024-026-037>040-054>056-058-059.
WINTER STORM WARNING FROM 7 AM SATURDAY TO 7 AM CDT SUNDAY FOR
KSZ008>010-020>022-034>036.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
140 PM CDT FRI MAR 22 2013
...UPDATED WITH A LATE AVIATION DISCUSSION...
.SYNOPSIS...
ISSUED AT 252 AM CDT FRI MAR 22 2013
THE BULK OF THE POLAR JET ENERGY WAS POSITIONED ACROSS THE SOUTHERN
ROCKIES, THROUGH THE SOUTHERN PLAINS, WRAPPING THROUGH THE SOUTHEAST
UNITED STATES JUST SOUTH OF THE NORTHEAST U.S. BROAD CLOSED LOW. A
SECOND SIGNIFICANT UPPER JET WAS DIVING SOUTHWARD ON THE HEELS OF
THE FIRST, INTO THE NORTHWEST PACIFIC REGION COASTLINE. THE MID
LEVELS EXHIBITS COLD 500 MB AIR TEMPERATURES BELOW -20 DEGREES
ACROSS MOST OF THE CONUS. THE AIR ASSOCIATED WITH THE 500 MB TROUGH
ACROSS THE NORTHWEST U.S. WAS -30 TO NEAR -40 DEGREES C. A STRONG
TEMPERATURE GRADIENT REMAINED IN PLACE FROM CENTRAL KANSAS, WHICH
MARKED THE EDGE OF THE FREEZING AT AT THE 850 MB LEVEL...TO THE
TEXAS PANHANDLE WHERE WARM +20 DEGREE C AIR WAS IN PLACE. RAIN AND
SNOW WERE FALLING ACROSS NORTHWEST KANSAS INTO SOUTH CENTRAL
NEBRASKA, ASSOCIATED WITH A STRONG BAROCLINIC ZONE AND ISENTROPIC
LIFT.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 252 AM CDT FRI MAR 22 2013
NUMEROUS SNOW SHOWERS CONTINUE TO DRIFT FROM WEST CENTRAL INTO
CENTRAL KANSAS THIS MORNING. THE HIGHEST CONCENTRATION OF SNOW
SHOWERS WILL MOVE THROUGH THE RUSH CENTER TO STAFFORD AND SAINT JOHNS
AREAS THOUGH 5 AM. AREAS TO THE SOUTH WILL FIND THE SHOWERS REALIZED
AS EITHER RAIN OR SNOW PRECIPITATION TYPE, AS WARMER TEMPERATURES
ARE FOUND NEAR THE OKLAHOMA LINE. BASED ON THE RAPID REFRESH THE
PRECIPITATION SHOULD CLEAR THE AREA BY 11 UTC. HOWEVER, LOW LEVEL
STRATUS WILL PERSIST THROUGH THE MORNING UNTIL THE STRONG MARCH SUN
CAN WARM THE BOUNDARY LAYER SUFFICIENTLY TO INDUCE MIXING. THE
LATEST NAM MODEL SUGGESTS THIS SHOULD OCCUR RAPIDLY BETWEEN 15 AND
18 UTC. AS A RESULT, DRY AIR IN WESTERN KANSAS WILL ALLOW RAPID
WARMING INTO THE 60S BY THE AFTERNOON, WHILE CENTRAL KANSAS COUNTIES
FROM HAYS TO PRATT AND MEDICINE LODGE WILL BE SLOWER TO RESPOND.
WEAK EASTERLY UPSLOPE WINDS SHOULD PERSIST THROUGH THE DAY, BEFORE
TURNING SLIGHTLY MORE SOUTHEASTERLY FOR A FEW HOURS IN RESPONSE TO
SURFACE CYCLOGENESIS OVER EASTERN COLORADO THROUGH THE EVENING AND
INTO TONIGHT.
WITH THE COOL STABLE BOUNDARY LAYER AIRMASS ACROSS CENTRAL KANSAS IN
PLACE, RAPID STRATUS REDEVELOPMENT SHOULD OCCUR AGAIN BEFORE
MIDNIGHT. MODEL CONSENSUS INDICATES WARM ADVECTION PRECIPITATION
CONVECTIVE SHOWERS ARE POSSIBLE THIS EVENING ACROSS THE FAR
SOUTHWEST KANSAS COUNTIES, ASSOCIATED WITH THE NEXT SYNOPTIC SCALE
STORM. CHANCES ARE GOOD THAT THE INITIAL SHOWERS WILL BECOME MORE
NUMEROUS THROUGH THE OVERNIGHT HOURS, AND LIKELY QUICKLY CAUSE
SURFACE TEMPERATURES ACROSS WESTERN KANSAS TO DROP TO THE WET BULB
TEMPERATURE CAUSING A PHASE CHANGE TO SNOW OVERNIGHT. AN INCH OR TWO
OF SNOW COULD BE POSSIBLE ACROSS ANY AREAS OF WEST CENTRAL KANSAS
THROUGH THE INTERSTATE 70 CORRIDOR BY 12Z SATURDAY.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 429 AM CDT FRI MAR 22 2013
WINTER STORM STILL THE FOCUS OF THE LONG TERM SECTION...WITH IMPACTS
THE MAIN CHALLENGE...IN TERMS OF TIMING AND SEVERITY...AND WHO WILL
GET THE BRUNT OF THE STORM.
400MB POTENTIAL VORTICITY (PV) STREAM EVIDENT ON RAP ANALYSIS AND
WATER VAPOR LOOP THIS MORNING FROM SOUTHWESTER BRITISH COLUMBIA TO
SOUTHWESTERN IDAHO. THIS STREAM OF HIGH PV AIR WILL AID IN THE
FORMATION OF A MID LEVEL CYCLONE BY EARLY SATURDAY OVER WESTERN
COLORADO. THE INCREASED UPPER TROPOSPHERIC JET STREAK DYNAMICS
ASSOCIATED WITH THE STORM WILL AID IN LOW LEVEL CYCLOGENESIS AS WELL
BY EARLY SATURDAY MORNING. SATURATION WILL OCCUR IN THE LOW LEVELS
WITH INITIAL PRECIPITATION BREAKING OUT LATE IN THE FRIDAY NIGHT
PERIOD INTO EARLY SATURDAY AS WARM, MOIST FRONTOGENESIS INCREASES
DRAMATICALLY IN THE 800-700MB LAYER. AS THE LOWER-MID TROPOSPHERIC
COLUMN SATURATES EARLY SATURDAY...THE VERTICAL THERMODYNAMIC PROFILE
WILL QUICKLY SUPPORT SNOW AS THE PROFILE GOES BELOW ZERO DEGC OVER
MUCH OF SOUTHWEST KANSAS...ESPECIALLY BY 18Z SATURDAY. THE SNOW WILL
INITIALLY BE A VERY WET SNOW AS SURFACE TEMPERATURES WILL BE IN THE
32 TO 35 DEGREE RANGE WITH A PREDOMINANTLY EAST TO EAST-NORTHEAST
SURFACE WIND THROUGH MIDDAY. BY AFTERNOON...SURFACE TEMPERATURES
WILL APPROACH 30 AND LOW LEVEL COLD ADVECTION WILL INCREASE WHICH
WILL ENHANCE THE DROP IN TEMPERATURE...ESPECIALLY WEST OF HIGHWAY
83. THE WINDS WEST OF HIGHWAY 83 WILL BECOME NORTH AND INCREASE TO
25 TO 30 MPH. THERE IS SOME CONCERN THAT GIVEN THE MAGNITUDE OF WIND
AND POTENTIAL ONE HALF TO ONE-INCH PER HOUR SNOWFALL RATES BY LATE
IN THE DAY...THAT WHITE-OUT OR NEAR WHITE-OUT CONDITIONS WILL OCCUR.
THE SNOW WILL BECOME INCREASINGLY SUSCEPTIBLE TO BLOWING AS
TEMPERATURES FALL INTO THE UPPER 20S BY 00Z AS FAR EAST AS HIGHWAY
283 (WAKEENEY TO DODGE CITY TO ASHLAND LINE). TEMPERATURE AND TIME
OF DAY WILL HAVE A HUGE IMPACT ON THE BLOWING AND DRIFTING OF
SNOW...LEADING TO THE NEAR-BLIZZARD OR EVEN BLIZZARD THREAT. IF THE
BRUNT OF THE STORM WAS TO OCCUR DURING THE MIDDLE OF THE DAY WITH
SURFACE TEMPERATURES IN THE 32 TO 34 DEGREE RANGE...THE THREAT FOR
BLOWING SNOW WOULD BE GREATLY REDUCED DUE TO THE VERY WET NATURE AND
COMPOSITION OF SNOW (LARGE, WET AGGREGATE FLAKES VS. DRIER
INDIVIDUAL DENDRITES). THE DENDRITIC GROWTH ZONE (-12C TO -16C) WILL
BE IN THE FAVORED 750-650MB LAYER DURING THE 00-09Z TIME FRAME
SUNDAY IN THE MID LEVEL DEFORMATION ZONE WHICH WILL AID IN SLIGHTLY
HIGHER SNOWFALL RATIO THAN WHAT WOULD TYPICALLY BE EXPECTED FOR LATE
MARCH...SO THIS IS SOMETHING TO KEEP IN MIND AS WELL.
GIVEN ALL OF THE ABOVE MENTIONED...AND WITH THE MID LEVEL
FRONTOGENETIC ZONE LIKELY JUST FAR ENOUGH SOUTH TO IMPACT THE
SOUTHERN COUNTIES (USING THE ECMWF AND CANADIAN GEM MORE SOUTHERN
SCENARIO)...WILL ISSUE A WINTER WEATHER ADVISORY IN THE SOUTHERN
COUNTIES NOT CURRENTLY IN THE WINTER STORM WATCH (ROUGHLY ARKANSAS
RIVER SOUTH TO THE OKLAHOMA BORDER). AS FAR AS STORM TOTAL SNOWFALL
AMOUNTS GO...THIS IS STILL A VERY DIFFICULT FORECAST AND WILL LIKELY
COME DOWN TO THE MESOSCALE COMPONENTS OF THE STORM ITSELF (AS IS
TYPICALLY THE CASE). THAT BEING SAID...IT STILL LOOKS LIKE THE
NORTHERN HALF OF THE FORECAST AREA (ARKANSAS RIVER TO INTERSTATE 700
WILL SEE TOTAL SNOWFALL IN THE 4 TO 7 INCH RANGE WITH A FEW 8 INCH
AMOUNTS POSSIBLE IN SOME SPOTS. FROM THE ARKANSAS RIVER SOUTH TO THE
OKLAHOMA BORDER...3 TO 5 INCHES IS THE FORECAST.
THE STORM WILL QUICKLY EXIT EAST SUNDAY MORNING WITH SOME REMNANT
LIGHT BLOWING AND DRIFTING THROUGH THE MORNING HOURS AFTER SUNRISE
SUNDAY. THE MARCH SUN WILL AID IN SNOWMELT ON ROAD SURFACES...BUT IT
WILL HAVE SOME WORK TO DO AS STRONG COLD ADVECTION WILL CONTINUE
THROUGH THE DAY AND 2-METER TEMPERATURES WILL STAY IN THE 20S MOST
OF THE DAY.
UNFORTUNATELY...HAVE HAD NO TIME TO ADDRESS THE FORECAST BEYOND
SUNDAY AND RUNNING WITH THE LATEST ALLBLEND GUIDANCE WHICH CALLS FOR
A SLOW WARM-UP MONDAY AND TUESDAY (30S AND 40S). BY WEDNESDAY...WE
SHOULD SEE A FAIRLY DRAMATIC WARM-UP BACK INTO THE 50S AND PERHAPS
60S. AFTER THIS BRIEF WARM-UP BACK TO CLIMO...WE WILL MOST LIKELY
ENTER ANOTHER COLD SPELL GOING INTO THE DAY 7-10 TIME FRAME AS WE
END THE MONTH OF MARCH.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 135 PM CDT FRI MAR 22 2013
FOR THE REST OF TODAY, SKIES WILL BE MOSTLY CLEAR AS A SMALL WEDGE
OF HIGH PRESSURE CONTROLS THE AREA. A LARGE UPPER LEVEL SYSTEM IS
MOVING TOWARD WESTERN KANSAS FROM THE WEST. WINDS WILL BASICALLY
BE LIGHT AND VARIABLE THROUGH 23Z, THEN BECOME EAST AT AROUND 15 KNOTS.
OVERNIGHT, LOW LEVEL MOISTURE WILL RIDE UP FROM THE SOUTH AND
SOUTHEAST, AND DEVELOP INTO IFR CIGS AFTER 09Z TONIGHT. THE BIGGER
SHOW OF DRIZZLE AND THEN SNOW COMES LATER ON SATURDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 34 35 23 30 / 10 90 90 10
GCK 32 33 21 30 / 10 90 90 0
EHA 36 37 21 34 / 10 90 80 10
LBL 37 38 23 34 / 10 90 80 10
HYS 29 31 23 30 / 90 90 90 30
P28 35 38 28 35 / 10 90 80 40
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM 1 AM CDT /MIDNIGHT MDT/ SATURDAY THROUGH
SUNDAY MORNING FOR KSZ030-031-043>046-061>066.
WINTER WEATHER ADVISORY FROM 10 AM SATURDAY TO 7 AM CDT SUNDAY
FOR KSZ074>081-084>090.
&&
$$
SYNOPSIS...RUSSELL
SHORT TERM...RUSSELL
LONG TERM...UMSCHEID
AVIATION...BURKE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
144 PM EDT FRI MAR 22 2013
.UPDATE...
ISSUED AT 1040 AM EDT FRI MAR 22 2013
SOME SLIGHTLY DEEPER MOISTURE HAS MOVED INTO THE AREA...JUST ENOUGH
TO ALLOW SOME SNOW TO MIX IN WITH THE FREEZING DRIZZLE DUE TO THE
TOP OF THE CLOUD BEING AROUND -12C. HOWEVER...THIS IS EXPECTED TO
ONLY LAST A FEW HOURS PER THE RAP SOUNDINGS. OTHERWISE...HAVE OPTED
TO KEEP FREEZING DRIZZLE AROUND FOR MUCH OF THE DAY CLOSER TO LAKE
SUPERIOR DUE TO THE PERSISTENT UPSLOPE FLOW THROUGH THE DAY AND
SHALLOW MOISTURE. ANY SURFACES THAT ARE UNTREATED MAY BE SLIPPERY AT
TIMES.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 505 AM EDT FRI MAR 22 2013
UPR LEVEL TROUGH DRIFTS FARTHER EAST OF UPR LAKES WITH RIDGING
POISED TO MOVE IN FOR THE WEEKEND. STRONG SFC LOW SPINS NEAR
CANADIAN MARITIMES WITH WEAKER LOW OVER QUEBEC. WEAK TROUGH STILL
EXTENDS WESTWARD ACROSS UPR LAKES REGION FROM THE QUEBEC LOW. HIGH
PRESSURE UPSTREAM OVER MANITOBA WILL ONLY SLOWLY MOVE TOWARD GREAT
LAKES. RESULT IS WEAK CYCLONIC/NEUTRAL LOW-LEVEL FLOW THAT KEEPS
CHANCES OF SNOW SHOWERS/FLURRIES IN THROUGH SATURDAY. AT A MINIMUM...
SKIES ACROSS MUCH OF CWA WILL TEND TO STAY ON THE CLOUDIER SIDE.
BETTER PRECIP CHANCES...AND THEY ARE ON THE SMALLER SIDE...OCCUR
TODAY AS H95-H9 TROUGH DROPS ACROSS LK SUPERIOR INTO NORTHERN CWA
THIS MORNING. PLENTY OF H95-H9 MOISTURE SEEN UPSTREAM IN ONTARIO ON
00Z YPL AND WZC SOUNDINGS. GENERALLY NAM/GFS/LOCAL-WRF INITIALIZED
YPL SOUNDING WELL BUT WERE TOO MOIST ABOVE H95 AT MOOSINEE. ONCE THE
MOISTURE ARRIVES THROUGH 12Z...THINK IT WILL UPSLOPE AND BE LIFTED
OVER COLD DOME OF AIR IN PLACE AND GRADUALLY LOWER/THICKEN. 925-900MB
TEMPS OF -8C TO -10C JUST COLD ENOUGH FOR LK EFFECT SNOW SHOWERS OR
FLURRIES. COVERAGE WILL BE SPOTTY THOUGH AS OVER-WATER INSTABILITY
IS MARGINAL. PUT SOME FZDZ IN EARLIER AS THERE WERE REPORTS UPSTREAM
IN ONTARIO WITH CIGS BLO 010. CIGS THUS FAR OVR UPR MICHIGAN ARE
MORE TOWARD 2KFT WHICH SEEMS TOO HIGH TO SEE ENOUGH SATURATION FOR
FZDZ. WILL PULL THE MENTION OF FZDZ.
STAYED PESSIMISTIC FOR CLOUD COVER TONIGHT GIVEN AMOUNT OF MOISTURE
UPSTREAM. BUT...TONIGHT THERE IS ALSO MORE DIFFLUENT SFC-H9 FLOW SO
CONVERGENCE WILL BE AT A PREMIUM...LEADING TO BREAKS DEVELOPING IN
THE CLOUD COVER. OTHER THAN ISOLD SHSN IN THE EVENING OVR MARQUETTE
COUNTY WITH WEAK ONSHORE/UPSLOPE FLOW...KEPT FORECAST DRY FOR
TONIGHT. MIN TEMPS WILL BE TRICKY AS IT WILL ALL DEPEND ON WHERE
CLOUDS PERSIST. BETTER CHANCE FOR CLEARING WOULD BE OVER SW CWA WITH
MORE OF SIGNAL FOR LGT AND DIFFLUENT WINDS. MIN TEMPS IN THAT AREA
MAY DROP TO 5 ABOVE. ELSEWHERE WITH THE CLOUDS AND SOME WIND...MIN
TEMPS SHOULD STAY IN THE TEENS. ALL IN ALL...PRETTY QUIET WEATHER
COMPARED TO THE ACTIVE WEATHER PATTERN EXPERIENCED RECENTLY.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 505 AM EDT FRI MAR 22 2013
A BLOCKING PATTERN WITH HIGH LATITUDE RIDGING FROM GREENLAND INTO
NORTHEAST CANADA IS EXPECTED TO PERSIST THROUGH THE PERIOD. THIS WILL
RESULT IN TROUGHING INTO THE N CNTRL AND ERN CONUS KEEPING BELOW
NORMAL TEMPS IN PLACE. HIGHS IN THE LOWER TO MID 30S ARE EXPECTED
WITH LOWS GENERALLY IN THE TEENS TO LOWER 20S.
SAT INTO SAT NIGHT...EVEN THOUGH MODELS SHOW LARGE SCALE SUBSIDENCE
PREVAILING...WITH PERSISTENT NRLY FLOW AND 825-800MB MOISTURE ALONG
WITH 850 MB TEMPS IN THE -10C TO -12C RANGE...SOME LIGHT LAKE EFFECT
SNOW SHOWERS OR FLURRIES WILL REMAIN POSSIBLE. WITH GREATER LATE
MARCH DAYTIME HEATING...A DIURNAL COMPONENT TO THE -SHSN IS ALSO
EXPECTED. SO...ANY FLURRIES SHOULD DIMINISH DURING THE EVENING.
SUN AND MON...AS A MID LEVEL LOW MOVES EAST FROM THE OHIO
VALLEY...THE GFS/ECMWF SUGGEST THAT ANOTHER BATCH OF 850-700 MB
MOISTURE WILL BE DRAWN TOWARD UPPER MICHIGAN FROM THE NORTHEAST. THE
MOISTURE COMBINED WITH NNE FLOW 850 MB TEMPS REMAINING IN THE -10C
TO -12C RANGE WILL BE ENOUGH TO SUPPORT SNOW SHOWERS CHANCES INTO
THE NW HALF OF THE CWA MON THAT MAY LINGER INTO MON NIGHT.
HOWEVER...ANY SNOWFALL AMOUNT SHOULD REMAIN LIGHT...LESS THAN A HALF
INCH.
TUE-THU...THE ECMWF/GEM WERE SLOWER WITH THE COMPACT MID LEVEL LOW
THAT IS EXPECTED TO SLIDE FROM CNTRL CANADA INTO THE UPPER MS VALLEY
OF WRN GREAT LAKES COMPARED TO THE GFS. DESPITE MODEL DIFFERENCES
REGARDING THIS FEATURE...THE PERSISTENT NRLY LOW LEVEL FLOW PATTERN
WILL KEEP POTENTIAL FOR SOME LIGHT SNOW OR FLURRIES GOING. SINCE ANY
SHORTWAVES IN THE NW MID LEVEL FLOW WILL BE WEAK...EXPECT CHANCE FOR
ANY MEASURABLE SNOW WILL REMAIN ONLY SLIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 144 PM EDT FRI MAR 22 2013
EXPECT -SHSN AND LIGHT DRIZZLE/BR THIS AFTERNOON AT SAW AND CMX TO
DIMINISH AS LOW LEVEL MIXING OCCURS. MOISTURE THEN INCREASES TONIGHT
WITH CONTINUE NLY LOW LEVEL WINDS...SO -FZDZ WILL REOCCUR AS IT DID
THIS MORNING AND CONTINUE INTO SAT MORNING. ONCE LOW LEVEL MIXING
INCREASING LATE SAT MORNING...SHOULD SEE -FZDZ DIMINISH.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 505 AM EDT FRI MAR 22 2013
HIGH PRESSURE OVER CNTRL CANADA EXPANDS INTO THE GREAT LAKES THROUGH
NEXT WEEK. PLAN ON QUIET CONDITIONS ON LK SUPERIOR WITH WINDS LESS
THAN 25 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...MRD
SHORT TERM...JLA
LONG TERM...JLB
AVIATION...TITUS
MARINE...JLA
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1229 PM CDT FRI MAR 22 2013
.AVIATION...18Z TAF ISSUANCE...
AREAS OF BKN MVFR CIGS ARE LINGERING ACROSS THE REGION EARLY THIS
AFTERNOON WITH A BAND OF MID LVL CLOUDS EXTENDING FROM FGN TO TWM
TO PBH. MVFR CIGS HAVE MOVED IN OVER DLH AND COULD REMAIN THROUGH
THE AFTERNOON WITH A WEAK NE WIND OFF THE LAKE SUPPLEMENTING THE
AVAILABLE MOISTURE. QUITE A BIT OF UNCERTAINTY REGARDING CIG
FORECAST TODAY. A BETTER CHANCE OF LOW CLOUDS TONIGHT. WINDS WILL
REMAIN LIGHT THROUGH THE PERIOD.
&&
.PREV DISCUSSION... /ISSUED 924 AM CDT FRI MAR 22 2013/
UPDATE...PROGRESSIONS OF CLOUDS THROUGH THE ARROWHEAD AND ALONG
THE INTERNATIONAL BORDER HAS SLOWED QUITE A BIT. THERE IS SOME
EROSION OCCURRING ALONG THE LEADING EDGE. HAVE UPDATED THE SKY
GRIDS TO ACCOUNT FOR THIS TREND. RAISED MAX TEMPS A BIT AS TEMPS
ARE RECOVERING QUICKLY WHERE THERE IS FULL SUN...AND ESPECIALLY IN
THE FORESTED AREAS IN NW WI. BROUGHT DEWPOINTS UP AS WELL FOR THE
SAME REASON.
PREV DISCUSSION... /ISSUED 652 AM CDT FRI MAR 22 2013/
AVIATION...12Z TAF ISSUANCE.
A WIDESPREAD STRATUS DECK WITH CEILINGS OF 1-2 KFT IS CURRENTLY
RESIDING OVER ONTARIO...SINKING GRADUALLY OVER NE MINNESOTA AND
WESTERN LAKE SUPERIOR. EXPECTING THE LOW CLOUDS AND MVFR CIGS TO MAINLY
AFFECT THE KINL/KHIB/KDLH TERMINALS THROUGH 18Z...WHERE HAVE
HANDLED WITH TEMPO GROUPS AT THIS TIME. LATEST MODEL RUNS SUGGEST
THE LOW CLOUDS RETREAT BACK TO THE NORTHEAST THROUGH THE LATE
MORNING AND ALLOW WIDESPREAD VFR CIGS ACROSS ALL TERMINALS THIS
AFTERNOON. HOWEVER...THE ANTICIPATED CLEARING IN THE NORTHERN
ZONES WILL BE SHORT LIVED AS ANOTHER ROUND OF LOW CLOUDS ARE
FORECAST TO SPREAD BACK INTO THE REGION OVERNIGHT...MAINLY AFTER
02Z.
PREV DISCUSSION... /ISSUED 259 AM CDT FRI MAR 22 2013/
SHORT TERM...THROUGH SATURDAY.
THE NORTHLAND WILL REMAIN BETWEEN UPPER TROUGHS TODAY...WITH
NARROW RIDGING...THEN WE WILL BECOME INCREASINGLY UNDER THE
INFLUENCE OF THE WESTERN TROUGH AS IT MOVES TOWARD THE REGION
TONIGHT INTO SATURDAY.
THE MAIN FOCUS TODAY WILL BE ON CLOUD COVER...AS LOW LEVEL
NORTHEASTERLY FLOW WAS ALREADY SPREADING CLOUDS INTO THE THE
ARROWHEAD AND THROUGH NORTHWEST ONTARIO. THE NAM...ECMWF AND THE
RAP...WERE DOING A DECENT JOB HANDLING THESE CLOUDS THIS MORNING.
THE ECMWF SUGGESTS THE CLOUDS WILL DIMINISH THIS AFTERNOON...THE
RAP HOLDS THEM IN TODAY AND SPREADS THEM WELL SOUTH INTO OUR CWA.
THE NAM IS A COMPROMISE. WE DO EXPECT SOME THINNING OF THOSE
CLOUDS THIS AFTERNOON...THE RAP WAS WAY OVERDONE YESTERDAY. WE
INCREASED SKY COVER OVER THE NORTHERN AND EASTERN CWA
TODAY...ESPECIALLY THIS MORNING. WE KEPT THE FORECAST DRY TODAY
INTO TONIGHT...BUT WOULD NOT BE SURPRISED IF SOME FLURRIES
DEVELOPED. OVERALL...WE EXPECT HIGHS TODAY FROM 29F TO 35F.
TONIGHT...WITH PERSISTENT LOW LEVEL NORTHEAST FLOW WE EXPECT THE
CLOUDS TO EXPAND WEST AND SOUTH THROUGH MUCH OF THE CWA AND HAVE
MOST AREAS MOSTLY CLOUDY TONIGHT INTO SATURDAY. THE CLOUDS SHOULD
HOLD TEMPS UP TONIGHT...AND WE HAVE THEM FROM 8F TO 14F. SOME
POCKETS OF COLDER TEMPS WILL BE POSSIBLE IN ANY AREAS THAT SEE AN
EXTENDED PERIOD OF MOSTLY CLEAR SKIES...SINCE WINDS WILL BE LIGHT.
A SHORTWAVE WILL ROTATE THROUGH THE AREA ON SATURDAY...AND SHOULD
BE ENOUGH TO SET OFF SOME FLURRIES. WE HAVE SCATTERED FLURRIES
MAINLY OVER OUR MINNESOTA ZONES...INTO FAR NORTHWEST WISCONSIN.
HIGHS SHOULD REBOUND TO 30F TO 35F FOR MOST AREAS.
LONG TERM...SAT NIGHT THROUGH FRIDAY.
THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT
OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH
OVER THE ROCKIES THROUGH THE WEEKEND WITH A PERSISTENT NORTH TO
NORTHEAST BDRY LAYER FLOW. MODELS IN GOOD AGREEMENT THAT A VORT MAX
EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST ACROSS THE SRN
PLAINS THROUGH SUNDAY. MEANWHILE...LATEST MODEL RUNS ARE SUGGESTING A
SHORT WAVE BREAKS FREE FROM MAIN FLOW AND LIFTS INTO THE UPPER
PLAINS. THE 00Z RUNS OF THE ECM/NAM/GFS ALL SHOW THE SHORT WAVE
BECOMES A CLOSED H50 LOW IN THE VCNTY OF MONTANA/WRN DAKOTAS BY
SUNDAY MORNING. ATTM...HAVE KEPT FCST DRY THROUGH THE WEEKEND AS THE
FORCING/PRECIP FROM THE WAVE IN THE DAKOTAS LOOKS TO REMAIN TO THE
WEST OF THE FA...WHILE THE SOUTHERN STREAM LOW STAYS WELL OFF TO THE
SOUTH. HOWEVER...RH FIELDS AND LATEST NAM BUFR SOUNDINGS CONTINUE TO
SHOW INCREASING LOW LEVEL MOISTURE SAT NIGHT/SUN...SO HAVE
INTRODUCED BROAD BRUSH FLURRIES DURING THIS TIME. THE ONSHORE WINDS
MAY ALLOW FOR ADDITIONAL LIFT/ENHANCEMENT TO PRODUCE A FEW LIGHT SNOW
SHOWERS ALONG SOUTH SHORE OF LAKE SUPERIOR SUNDAY THROUGH EARLY NEXT
WEEK.
BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS
MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST.
LATEST RUNS OF THE ECM/GEM/GFS ARE ALL SUGGESTING A H50 CLOSED LOW
RETROGRADES ACROSS HUDSON BAY AND TRACKS INTO MANITOBA THROUGH
MONDAY. FROM HERE THERE ARE LARGE MODEL DIFFERENCES IN THE TRACK OF
THE VORT MAX AS THE ECM KEEPS THE LOW NEARLY STATIONARY OVER
MANITOBA...WHILE THE GFS DROPS THE LOW ACROSS THE DLH CWA THROUGH
MID-WEEK.
&&
.POINT TEMPS/POPS...
DLH 14 34 17 31 / 0 10 10 10
INL 8 33 15 32 / 0 10 10 10
BRD 11 35 18 32 / 0 10 10 10
HYR 8 35 16 34 / 0 10 10 10
ASX 12 34 17 32 / 0 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
AVIATION...TENTINGER
AREA FORECAST DISCUSSION...UPDATED
NWS SAN ANGELO TX
103 PM CDT FRI MAR 22 2013
.DISCUSSION...
SEE AVIATION SECTION.
&&
.AVIATION...
THE LOW CLOUD FIELD ACROSS THE BIG COUNTRY WILL CONTINUE TO SLOWLY
ERODE THIS AFTERNOON. EXPECT SCATTERED COVERAGE AT KABI 21-23Z. COLD
FRONTAL BOUNDARY WILL WEAKEN THROUGH THE REMAINDER OF THIS AFTERNOON
AS IT DRIFTS SOUTH ACROSS THE INTERSTATE 10 CORRIDOR. THE FRONTAL
BOUNDARY SHOULD STALL NEAR OR JUST SOUTH OF THE SOUTHERN BORDER OF
OUR FORECAST/WARNING AREA THIS EVENING. THE FRONT WILL RETURN NORTH
AS A WARM FRONT TONIGHT...WITH WINDS BECOMING SOUTHEAST OVERNIGHT.
EXPECT LOW CLOUDS TO DEVELOP AND EXPAND WEST ACROSS PARTS OF OUR AREA
AFTER 06Z...AND CEILINGS TO BE IN THE 1K-2K FT RANGE. WINDS WILL VEER
TO SOUTH EARLY SATURDAY MORNING. PACIFIC FRONT/DRYLINE PASSAGE EXPECTED
IN THE 15Z-18Z TIME FRAME...FOLLOWED BY INCREASING AND GUSTY WEST WINDS.
THIS WILL ALSO QUICKLY SCOUR OUT THE LOW-LEVEL MOISTURE AND CLOUD COVER.
&&
.PREV DISCUSSION... /ISSUED 1124 AM CDT FRI MAR 22 2013/
UPDATE...
FORECAST HAS BEEN UPDATED MAINLY FOR TEMPERATURES TODAY...
SEE DISCUSSION.
DISCUSSION...
SURFACE COLD FRONT HAS PROGRESSED INTO OUR SOUTHERN COUNTIES LATE
THIS MORNING. AT 11 AM THE FRONT EXTENDED FROM JUST SOUTH OF MASON
TO JUST NORTH OF OZONA. THE LATEST RUC13 AND NAM12 MODELS HAVE THE
FRONT MOVING AT A MUCH SLOWER PACE THIS AFTERNOON ACROSS OUR
SOUTHERNMOST COUNTIES. THIS FRONT IS EXPECTED TO STALL NEAR OR JUST
SOUTH OF OUR FORECAST/WARNING AREA THIS EVENING. LOW CLOUD COVER HAS
DEVELOPED AND PERSISTED ACROSS THE BIG COUNTRY...AND WAS MORE
PATCHY ACROSS THE SOUTHERN HEARTLAND AND SOUTHERN CONCHO VALLEY.
THE COMBINATION OF COLD AIR ADVECTION AND CLOUD COVER HAS RESULTED
IN LITTLE TEMPERATURE RECOVERY ACROSS THE BIG COUNTRY. THE MODEL
LOW-LEVEL MOISTURE FIELDS INDICATE THAT THE SOUTHERN END OF THE LOW
CLOUD FIELD ACROSS THE BIG COUNTRY WILL SLOWLY ERODE THIS AFTERNOON...
BUT SHOULD REMAIN PERSISTENT ACROSS THE NORTHERNMOST COUNTIES. WITH
THE COLD AIR ADVECTION BEHIND THE FRONT A LITTLE STRONGER THAN
PREVIOUSLY ANTICIPATED...HAVE LOWERED TEMPERATURES THIS AFTERNOON
ACROSS OUR NORTHERN AND CENTRAL COUNTIES. TEMPERATURES STILL LOOK ON
TARGET ACROSS THE FAR SOUTHERN PART OF OUR AREA. SHOULD END UP WITH
ABOUT A 30 DEGREE NORTH-SOUTH TEMPERATURE GRADIENT ACROSS WEST CENTRAL
TEXAS WITH THE HIGHS THIS AFTERNOON. FORECAST PRODUCTS HAVE BEEN UPDATED.
PREV DISCUSSION... /ISSUED 612 AM CDT FRI MAR 22 2013/
DISCUSSION...
SEE AVIATION DISCUSSION BELOW.
AVIATION...
VFR OR MVFR FLYING CONDITIONS ARE EXPECTED ACROSS WEST CENTRAL
TEXAS THE NEXT 24 HOURS. A COLD FRONT WILL MOVE FROM NORTH TO
SOUTH THROUGH THE FORECAST AREA TODAY. ALTHOUGH NO RAIN IS
EXPECTED FROM THE FRONT SOME LOW CLOUDS ARE EXPECTED TO MOVE
THROUGH THE AREA WITH IT. CLOUD CEILINGS COULD BRIEFLY LOWER
AIRPORT WEATHER CONDITIONS TO MVFR WITH BROKEN CLOUD COVER
POSSIBLY BECOMING OVERCAST BELOW THREE THOUSAND FEET.
ON SATURDAY A PACIFIC FRONT WILL BREEZE THROUGH THE FORECAST AREA
FROM WEST TO EAST BRINGING BRISK WINDS OF 20 TO 25 MPH WITH
HIGHER GUST ACROSS THE AREA SATURDAY AFTERNOON. RELATIVE HUMIDITY
WILL PLUMMET INTO THE TEENS AND SINGLE DIGITS AND WILL CLEAR AWAY
MOST LOW CLOUDS ACROSS THE FORECAST AREA BY AFTERNOON.
A THIRD COLD WILL MOVE FROM NORTH TO SOUTH ACROSS THE FORECAST
AREA LATE SATURDAY NIGHT AND EARLY SUNDAY MORNING. BRISK 20 TO 25
MPH NORTH WINDS WILL ACCOMPANY THIS FRONT AND BRING SIGNIFICANTLY
COOLER MORNING TEMPERATURES ACROSS THE AREA WITH LOWS NEAR OR
SLIGHTLY BELOW FREEZING ON MONDAY AND ON TUESDAY MORNING.
PREV DISCUSSION... /ISSUED 415 AM CDT FRI MAR 22 2013/
SHORT TERM...
LIGHT SOUTH SOUTHWEST WINDS OF 10 TO 15KT WILL PREVAIL THROUGH DAWN
HOURS ACROSS WEST CENTRAL TEXAS. A WEAK SURFACE LOW PRESSURE AREA
ABOUT 50 MILES NORTHEAST OF THROCKMORTON COUNTY WILL MOVE EAST BY
EARLY MORNING HOURS AND A COLD FRONT WILL MOVE THROUGH THE AREA ON
FRIDAY. WINDS FROM THE NORTH AT 12 TO 18KT WITH SOME HIGHER GUSTS
WILL FOLLOW IMMEDIATELY BEHIND THE COLD FRONT THAT WILL BE
ACCOMPANIED BY SOME LOW CLOUDS. BY EARLY FRIDAY EVENING WINDS FROM
THE NORTH WILL WEAKEN TO 10 TO 15KT AND ANY LOW CLOUDS ASSOCIATED
WITH THE FRONT WILL MOVE EAST OUT OF THE FORECAST AREA. LIGHT 5 TO
10 KT EAST AND NORTHEAST WINDS WILL DOMINATE OVERNIGHT FRIDAY INTO
EARLY SATURDAY AND SOME LOW CLOUDS AND MOISTER AIR WILL RETURN FROM
THE EAST TO EASTERN AND CENTRAL COUNTIES.
A FIRE WEATHER WATCH HAS BEEN ISSUED FOR MOST OF WEST CENTRAL TEXAS
FROM NOON TO 7PM SATURDAY...IN ASSOCIATION WITH A PACIFIC COLD FRONT
THAT WILL BLAST EAST THROUGH THE AREA BEGINNING LATE SATURDAY
MORNING. AFTERNOON AND EARLY EVENING WINDS ON SATURDAY WILL BLOW
FROM THE WEST AT 18 TO 22KT WITH HIGHER GUSTS AND WILL BE
ACCOMPANIED BY VERY DRY AIR...RELATIVE HUMIDITY WILL DROP INTO THE
LOW TEENS AND SINGLE DIGITS. NEAR CRITICAL FIRE WEATHER CONDITIONS
ARE EXPECTED AND RED FLAG WARNINGS MAY BE NECESSARY FOR SOME
COUNTIES SATURDAY AFTERNOON AND EARLY SATURDAY EVENING...ESPECIALLY
ACROSS WEST AND SOUTHWEST COUNTIES.
LONG TERM...
A STRONG COLD FRONT WILL PUSH THROUGH WEST CENTRAL TEXAS SATURDAY
EVENING. COULD SEE NORTH WINDS SUSTAINED NEAR 30 MPH...WITH GUSTS
IN THE LOWER 40S FOR SEVERAL HOURS BEHIND THE FRONT. THE AIR WILL
BE QUITE DRY...AND FIRE WEATHER CONDITIONS WILL CONTINUE TO BE
ELEVATED. FIRE DEPARTMENTS WORKING ANY WILDFIRES EARLIER ON
SATURDAY SHOULD BE ALERT TO THE SUDDEN CHANGE IN WIND DIRECTION.
FREEZE POSSIBLE MONDAY AND TUESDAY MORNING AS THE 1030 MB SURFACE
HIGH PRESSURE...WITH ORIGINS IN WESTERN CANADA...BUILDS DIRECTLY
OVER THE REGION. A BIT TOO EARLY TO KNOW HOW COLD IT WILL BE.
MODELS ARE SUGGESTING A LIGHT FREEZE IN THE 30 TO 32 RANGE
MONDAY MORNING...WITH PERHAPS A DEGREE OR TWO LOWER TUESDAY MORNING (DUE
TO WEAKER WINDS). IN ANY CASE...WITH THE GROWING SEASON
STARTING...LOOK FOR POTENTIAL FREEZE WARNINGS ISSUED LATER THIS
WEEKEND...IF CONDITIONS CONTINUE TO WARRANT.
LOW LEVEL MOISTURE WILL FINALLY RETURN MIDWEEK. MODELS DO NOT
INDICATED MUCH LIFT AND MID LEVELS ARE DRY...SO WILL NOT BE
ADDING ANY RAINFALL CHANCES.
04
FIRE WEATHER...
ELEVATED TO FIRE WEATHER CONDITIONS WILL OCCUR FRIDAY FROM THE
COMBINATION OF BRISK NORTH WINDS AND DRY AIR BEHIND A COLD FRONT.
NEAR CRITICAL FIRE WEATHER IS EXPECTED MIDDAY TO EVENING HOURS ON
SATURDAY...A FIRE WEATHER WATCH HAS BEEN ISSUED FOR MOST OF WEST
CENTRAL TEXAS FROM NOON TO 7PM SATURDAY. RED FLAG WARNINGS MAY BE
NECESSARY...WEST AND SOUTHWEST COUNTIES WILL BE MOST THREATENED.
LYONS
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 55 49 79 33 55 / 5 10 10 5 5
SAN ANGELO 72 53 86 38 59 / 0 10 10 5 5
JUNCTION 85 55 87 40 63 / 0 10 10 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY
EVENING FOR THE FOLLOWING ZONES: CALLAHAN...COKE...COLEMAN...
CONCHO...CROCKETT...FISHER...HASKELL...IRION...JONES...KIMBLE...
MASON...MCCULLOCH...MENARD...NOLAN...RUNNELS...SCHLEICHER...
STERLING...SUTTON...TAYLOR...TOM GREEN.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS SAN ANGELO TX
1124 AM CDT FRI MAR 22 2013
.UPDATE...
FORECAST HAS BEEN UPDATED MAINLY FOR TEMPERATURES TODAY...
SEE DISCUSSION.
&&
.DISCUSSION...
SURFACE COLD FRONT HAS PROGRESSED INTO OUR SOUTHERN COUNTIES LATE
THIS MORNING. AT 11 AM THE FRONT EXTENDED FROM JUST SOUTH OF MASON
TO JUST NORTH OF OZONA. THE LATEST RUC13 AND NAM12 MODELS HAVE THE
FRONT MOVING AT A MUCH SLOWER PACE THIS AFTERNOON ACROSS OUR
SOUTHERNMOST COUNTIES. THIS FRONT IS EXPECTED TO STALL NEAR OR JUST
SOUTH OF OUR FORECAST/WARNING AREA THIS EVENING. LOW CLOUD COVER HAS
DEVELOPED AND PERSISTED ACROSS THE BIG COUNTRY...AND WAS MORE
PATCHY ACROSS THE SOUTHERN HEARTLAND AND SOUTHERN CONCHO VALLEY.
THE COMBINATION OF COLD AIR ADVECTION AND CLOUD COVER HAS RESULTED
IN LITTLE TEMPERATURE RECOVERY ACROSS THE BIG COUNTRY. THE MODEL
LOW-LEVEL MOISTURE FIELDS INDICATE THAT THE SOUTHERN END OF THE LOW
CLOUD FIELD ACROSS THE BIG COUNTRY WILL SLOWLY ERODE THIS AFTERNOON...
BUT SHOULD REMAIN PERSISTENT ACROSS THE NORTHERNMOST COUNTIES. WITH
THE COLD AIR ADVECTION BEHIND THE FRONT A LITTLE STRONGER THAN
PREVIOUSLY ANTICIPATED...HAVE LOWERED TEMPERATURES THIS AFTERNOON
ACROSS OUR NORTHERN AND CENTRAL COUNTIES. TEMPERATURES STILL LOOK ON
TARGET ACROSS THE FAR SOUTHERN PART OF OUR AREA. SHOULD END UP WITH
ABOUT A 30 DEGREE NORTH-SOUTH TEMPERATURE GRADIENT ACROSS WEST CENTRAL
TEXAS WITH THE HIGHS THIS AFTERNOON. FORECAST PRODUCTS HAVE BEEN UPDATED.
&&
.PREV DISCUSSION... /ISSUED 612 AM CDT FRI MAR 22 2013/
DISCUSSION...
SEE AVIATION DISCUSSION BELOW.
AVIATION...
VFR OR MVFR FLYING CONDITIONS ARE EXPECTED ACROSS WEST CENTRAL
TEXAS THE NEXT 24 HOURS. A COLD FRONT WILL MOVE FROM NORTH TO
SOUTH THROUGH THE FORECAST AREA TODAY. ALTHOUGH NO RAIN IS
EXPECTED FROM THE FRONT SOME LOW CLOUDS ARE EXPECTED TO MOVE
THROUGH THE AREA WITH IT. CLOUD CEILINGS COULD BRIEFLY LOWER
AIRPORT WEATHER CONDITIONS TO MVFR WITH BROKEN CLOUD COVER
POSSIBLY BECOMING OVERCAST BELOW THREE THOUSAND FEET.
ON SATURDAY A PACIFIC FRONT WILL BREEZE THROUGH THE FORECAST AREA
FROM WEST TO EAST BRINGING BRISK WINDS OF 20 TO 25 MPH WITH
HIGHER GUST ACROSS THE AREA SATURDAY AFTERNOON. RELATIVE HUMIDITY
WILL PLUMMET INTO THE TEENS AND SINGLE DIGITS AND WILL CLEAR AWAY
MOST LOW CLOUDS ACROSS THE FORECAST AREA BY AFTERNOON.
A THIRD COLD WILL MOVE FROM NORTH TO SOUTH ACROSS THE FORECAST
AREA LATE SATURDAY NIGHT AND EARLY SUNDAY MORNING. BRISK 20 TO 25
MPH NORTH WINDS WILL ACCOMPANY THIS FRONT AND BRING SIGNIFICANTLY
COOLER MORNING TEMPERATURES ACROSS THE AREA WITH LOWS NEAR OR
SLIGHTLY BELOW FREEZING ON MONDAY AND ON TUESDAY MORNING.
PREV DISCUSSION... /ISSUED 415 AM CDT FRI MAR 22 2013/
SHORT TERM...
LIGHT SOUTH SOUTHWEST WINDS OF 10 TO 15KT WILL PREVAIL THROUGH DAWN
HOURS ACROSS WEST CENTRAL TEXAS. A WEAK SURFACE LOW PRESSURE AREA
ABOUT 50 MILES NORTHEAST OF THROCKMORTON COUNTY WILL MOVE EAST BY
EARLY MORNING HOURS AND A COLD FRONT WILL MOVE THROUGH THE AREA ON
FRIDAY. WINDS FROM THE NORTH AT 12 TO 18KT WITH SOME HIGHER GUSTS
WILL FOLLOW IMMEDIATELY BEHIND THE COLD FRONT THAT WILL BE
ACCOMPANIED BY SOME LOW CLOUDS. BY EARLY FRIDAY EVENING WINDS FROM
THE NORTH WILL WEAKEN TO 10 TO 15KT AND ANY LOW CLOUDS ASSOCIATED
WITH THE FRONT WILL MOVE EAST OUT OF THE FORECAST AREA. LIGHT 5 TO
10 KT EAST AND NORTHEAST WINDS WILL DOMINATE OVERNIGHT FRIDAY INTO
EARLY SATURDAY AND SOME LOW CLOUDS AND MOISTER AIR WILL RETURN FROM
THE EAST TO EASTERN AND CENTRAL COUNTIES.
A FIRE WEATHER WATCH HAS BEEN ISSUED FOR MOST OF WEST CENTRAL TEXAS
FROM NOON TO 7PM SATURDAY...IN ASSOCIATION WITH A PACIFIC COLD FRONT
THAT WILL BLAST EAST THROUGH THE AREA BEGINNING LATE SATURDAY
MORNING. AFTERNOON AND EARLY EVENING WINDS ON SATURDAY WILL BLOW
FROM THE WEST AT 18 TO 22KT WITH HIGHER GUSTS AND WILL BE
ACCOMPANIED BY VERY DRY AIR...RELATIVE HUMIDITY WILL DROP INTO THE
LOW TEENS AND SINGLE DIGITS. NEAR CRITICAL FIRE WEATHER CONDITIONS
ARE EXPECTED AND RED FLAG WARNINGS MAY BE NECESSARY FOR SOME
COUNTIES SATURDAY AFTERNOON AND EARLY SATURDAY EVENING...ESPECIALLY
ACROSS WEST AND SOUTHWEST COUNTIES.
LONG TERM...
A STRONG COLD FRONT WILL PUSH THROUGH WEST CENTRAL TEXAS SATURDAY
EVENING. COULD SEE NORTH WINDS SUSTAINED NEAR 30 MPH...WITH GUSTS
IN THE LOWER 40S FOR SEVERAL HOURS BEHIND THE FRONT. THE AIR WILL
BE QUITE DRY...AND FIRE WEATHER CONDITIONS WILL CONTINUE TO BE
ELEVATED. FIRE DEPARTMENTS WORKING ANY WILDFIRES EARLIER ON
SATURDAY SHOULD BE ALERT TO THE SUDDEN CHANGE IN WIND DIRECTION.
FREEZE POSSIBLE MONDAY AND TUESDAY MORNING AS THE 1030 MB SURFACE
HIGH PRESSURE...WITH ORIGINS IN WESTERN CANADA...BUILDS DIRECTLY
OVER THE REGION. A BIT TOO EARLY TO KNOW HOW COLD IT WILL BE.
MODELS ARE SUGGESTING A LIGHT FREEZE IN THE 30 TO 32 RANGE
MONDAY MORNING...WITH PERHAPS A DEGREE OR TWO LOWER TUESDAY MORNING (DUE
TO WEAKER WINDS). IN ANY CASE...WITH THE GROWING SEASON
STARTING...LOOK FOR POTENTIAL FREEZE WARNINGS ISSUED LATER THIS
WEEKEND...IF CONDITIONS CONTINUE TO WARRANT.
LOW LEVEL MOISTURE WILL FINALLY RETURN MIDWEEK. MODELS DO NOT
INDICATED MUCH LIFT AND MID LEVELS ARE DRY...SO WILL NOT BE
ADDING ANY RAINFALL CHANCES.
04
FIRE WEATHER...
ELEVATED TO FIRE WEATHER CONDITIONS WILL OCCUR FRIDAY FROM THE
COMBINATION OF BRISK NORTH WINDS AND DRY AIR BEHIND A COLD FRONT.
NEAR CRITICAL FIRE WEATHER IS EXPECTED MIDDAY TO EVENING HOURS ON
SATURDAY...A FIRE WEATHER WATCH HAS BEEN ISSUED FOR MOST OF WEST
CENTRAL TEXAS FROM NOON TO 7PM SATURDAY. RED FLAG WARNINGS MAY BE
NECESSARY...WEST AND SOUTHWEST COUNTIES WILL BE MOST THREATENED.
LYONS
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 55 49 79 34 55 / 5 10 10 5 5
SAN ANGELO 72 53 86 38 59 / 0 10 10 5 5
JUNCTION 85 55 87 43 63 / 0 10 10 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY
EVENING FOR THE FOLLOWING ZONES: CALLAHAN...COKE...COLEMAN...
CONCHO...CROCKETT...FISHER...HASKELL...IRION...JONES...KIMBLE...
MASON...MCCULLOCH...MENARD...NOLAN...RUNNELS...SCHLEICHER...
STERLING...SUTTON...TAYLOR...TOM GREEN.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
559 PM CDT FRI MAR 22 2013
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
310 PM CDT FRI MAR 22 2013
THE FORECAST IS FOCUSED ON THE LATE WEEKEND PRECIPITATION CHANCES
ACROSS PARTS OF THE AREA.
AS OF THIS AFTERNOON...WATER VAPOR LOOP OVERLAID WITH RAP 500MB
HEIGHT FIELDS SHOWS WEAK RIDGING MOVING ACROSS THE UPPER MIDWEST
WITH ANOTHER DIGGING NEGATIVELY TITLED SHORTWAVE TROUGH ACROSS THE
NORTHERN ROCKIES. THERE ARE FEW EMBEDDED VORTICITY IMPULSES IN
THAT FLOW...WHICH ARE THE PLAYERS FOR THE WEEKEND STORM SYSTEM. AT
THE SURFACE...HIGH PRESSURE RIDGE AXIS REMAINS SQUEEZED OVER THE
UPPER MIDWEST AND 24-HR PRESSURE/TEMPERATURE CHANGES ARE MINIMAL.
JUST A UPWARD NUDGE COMPARED TO YESTERDAY.
QUIET CONDITIONS LOOK TO PREVAIL INTO SATURDAY AS WEAK UPPER RIDGING
BUILDS INTO THE AREA DOWNSTREAM OF THE DEVELOPING TROUGH TO THE
WEST. ANOTHER CHILLY NIGHT ON TAP...THOUGH NOT AS COLD AS RECENT
NIGHTS AS THE AIRMASS CONTINUES TO BE MODIFIED. CLOUD TRENDS HAVE
BEEN TRICKY AS DRIER AIRMASS AS OBSERVED BY 22.12Z MPX/GRB/DVN
SOUNDINGS IS ERODING ANY EASTWARD PROGRESS OF HIGH LEVEL CLOUDS.
HAVE KEPT MOSTLY CLEAR SKIES AT LEAST THROUGH 03-06Z FOR MUCH OF
THE AREA. HOWEVER...500-700MB WARM AIR ADVECTION SATURDAY SHOULD BE
ENOUGH TO SPREAD MID/HIGH CLOUDS ACROSS THE AREA FROM THE SOUTHWEST.
HIGHS WERE NUDGED DOWN A FEW DEGREES TO REMOVE SOME OF THE LATE
MARCH CLIMATOLOGY BIAS...BUT LOW TO MID 30S STILL LOOK REASONABLE.
THE WEEKEND STORM SYSTEM THAT YESTERDAY WAS AIMING TO TRACK SOUTH
HAS NOW BECOME SLIGHTLY MORE INTERESTING FOR PARTS OF THE FORECAST
AREA AS THERE HAS BEEN A SHIFT BACK TO THE NORTH. OVERALL...THE MID
TO UPPER LEVEL SUPPORT HAS IMPROVED THANKS TO A STRONGER NORTHERN
STREAM SHORTWAVE...AND SOME IMPRESSIVE LIFT DYNAMICS. ALTHOUGH THE
BULK OF THE FORCING DOES REMAIN TO OUR SOUTH...THERE ARE A FEW
THINGS TO BE NOTED. FIRST...THE AREA IS FAVORABLY LOCATED IN THE
LEFT EXIT REGION OF THE 250MB JET PROVIDING DECENT DIVERGENCE ALOFT.
AS THE SYSTEM EJECTS INTO THE CENTRAL PLAINS AND MID MISSISSIPPI
RIVER VALLEY...BROAD BUT VERY PERSISTENT 280-290K ISENTROPIC LIFT IS
PRESENT SOUTH OF I-90 AND THERE IS A 6 TO 12 HOUR TIME FRAME SUNDAY
MORNING AND AFTERNOON WITH DECENT MID LEVEL WARM AIR ADVECTION. VERY
WEAK 700MB FRONTOGENESIS IS SEEN ACROSS NORTHEAST IOWA AND FAR
SOUTHERN WISCONSIN AS WELL. FINALLY...THE MODEL GUIDANCE SHOWS A
BRIEF PERIOD OF 500-300MB PV ADVECTION. ALL OF THE ABOVE POINT TO A
PERIOD OF LIGHT BUT ACCUMULATING SNOW...HOWEVER...THE BIGGEST
NEGATIVELY COMPETING FACTOR WILL BE THE STRONG NORTHEASTERLY FEED OF
VERY DRY AIR RESULTING IN SATURATION ISSUES...ESPECIALLY IN THE
AREAS WHERE THE FORCING IS GREATEST. THE SATURATION PROBLEMS WILL
EVAPORATE A LOT OF PRECIPITATION EARLY ON...LIMITING POTENTIAL
ACCUMULATIONS.
REGARDING POTENTIAL SNOWFALL AMOUNTS...MODEL GUIDANCE CAME IN WITH
MORE QPF...WITH THE 22.09Z SREF PLUMES SHOWING A MEAN OF 4 INCHES AT
KDBQ. THE SPREAD VARIES FROM SEVERAL MEMBERS AT ONLY AT A
TRACE...THEN A FEW GREATER THAN 8 INCHES. THAT TREND IS SEEN ACROSS
THE AREA...BUT TO A LESSER DEGREE AT KDEH...KLSE...KRST. COBB OUTPUT
FROM 22.12Z NAM VARIED FROM LESS THAN AN INCH ALONG I-90...TO AROUND
6 INCHES AT KDBQ...AND 4 TO 5 INCHES AT KMCW AND KALO. HOWEVER...NOT
CONFIDENT ENOUGH TO MOVE COMPLETELY IN THAT DIRECTION GIVEN
AFOREMENTIONED DRY AIR / SATURATION ISSUES. ATTEMPTED TO CUT MODEL
QPF BY 1/3 TO ACCOUNT FOR THIS AND THIS TRANSLATES INTO AROUND 2
INCHES POSSIBLE ACROSS NORTHEAST IOWA AND FAR SOUTHWEST
WISCONSIN...THEN A TRACE TO MAYBE 1 INCH ALONG THE I-90 CORRIDOR
FROM PRE-SUNRISE SUNDAY THROUGH SUNDAY NIGHT.
IN SHORT...CONFIDENCE IN LIGHT BUT ACCUMULATING SNOWFALL SUNDAY /
SUNDAY EVENING HAS GROWN FOR THE SOUTHERN PORTIONS OF THE AREA WITH
FLURRIES OR OCCASIONAL LIGHT SNOW FOR ALONG AND JUST SOUTH OF I-90.
HAVE INCREASED PRECIPITATION CHANCES FOR THESE AREAS.
.LONG TERM...MONDAY THROUGH FRIDAY
310 PM CDT FRI MAR 22 2013
IN THE WAKE OF THE SUNDAY/SUNDAY NIGHT STORM SYSTEM...A REINFORCING
SHOT OF COLDER AIR LOOKS TO FOLLOW FOR MONDAY INTO MUCH OF NEXT
WEEK. CLIMATE PREDICTION CENTER FORECASTS THE ATLANTIC OSCILLATION
TO REMAIN NEGATIVE THROUGH AT LEAST APRIL 1ST...WHICH SUPPORTS OUR
STRETCH OF UNSEASONABLY COLD TEMPERATURES. THE LATEST CFS
TEMPERATURE ANOMALIES SHOW BELOW NORMAL TEMPERATURES EVEN INTO MID
APRIL POSSIBLY. LONGWAVE TROUGHING CONTINUES ACROSS THE EASTERN HALF
OF THE CONUS...WITH A WESTERN UPPER LEVEL RIDGE DEVELOPING BY THE
END OF NEXT WEEK. 850MB STANDARDIZED ANOMALIES VARY FROM -0.5 TO
-1.5 EACH DAY NEXT WEEK...GIVING HIGHS IN THE LOWER TO MID 30S AND
OVERNIGHT LOWS IN THE TEENS. TO HELP TREND THE FORECAST
BETTER...HAVE COOLED HIGHS/LOWS EACH DAY TO REMOVE CLIMATOLOGY BIAS
IN THE MODEL CONSENSUS THAT IS BEING INTRODUCED. THE THEME OF DRY
BUT COLD CONTINUES...WITH NO STORM SYSTEMS ON THE HORIZON UNTIL NEXT
WEEKEND POSSIBLY.
&&
.AVIATION...TONIGHT AND SATURDAY
559 PM CDT FRI MAR 22 2013
A RIDGE OF HIGH PRESSURE OVER THE TAF SITES IS FORECAST TO BREAK
DOWN OVER THE NEXT 24 HOURS AS LOW PRESSURE DEVELOPS OVER THE
CENTRAL PLAINS. AS THIS OCCURS...NORTHEAST FLOW WILL VERY SLOWLY
DEVELOP IN THE LOWER LEVELS OF THE ATMOSPHERE. LOOKING TO THE
NORTHEAST...THERE IS A MVFR-VFR STRATUS ACROSS FAR NORTHEAST
WISCONSIN INTO UPPER MICHIGAN. WITH WINDS BASICALLY LIGHT AND
VARIABLE TONIGHT...ANTICIPATING THAT THIS STRATUS DECK WILL NOT
MOVE MUCH. A BETTER SHOT OF THE STRATUS MOVING TOWARDS THE TAF
SITES COMES TOMORROW AS THE NORTHEAST WIND PICKS UP. EVEN
THEN...DAYTIME HEATING SHOULD BE ENOUGH TO MIX THE STRATUS DECK TO
A VFR CEILING AT BOTH TAF SITES. OTHERWISE...SOME ALTOSTRATUS WILL
GRADUALLY SPREAD ACROSS THE TAF SITES DURING THE NEXT 24
HOURS...WELL AHEAD OF THE DEVELOPING STORM SYSTEM. THIS
ALTOSTRATUS IS ALREADY APPROACHING KRST THIS EVENING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
310 PM CDT FRI MAR 22 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM...ZT
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
310 PM CDT FRI MAR 22 2013
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
310 PM CDT FRI MAR 22 2013
THE FORECAST IS FOCUSED ON THE LATE WEEKEND PRECIPITATION CHANCES
ACROSS PARTS OF THE AREA.
AS OF THIS AFTERNOON...WATER VAPOR LOOP OVERLAID WITH RAP 500MB
HEIGHT FIELDS SHOWS WEAK RIDGING MOVING ACROSS THE UPPER MIDWEST
WITH ANOTHER DIGGING NEGATIVELY TITLED SHORTWAVE TROUGH ACROSS THE
NORTHERN ROCKIES. THERE ARE FEW EMBEDDED VORTICITY IMPLUSES IN
THAT FLOW...WHICH ARE THE PLAYERS FOR THE WEEKEND STORM SYSTEM. AT
THE SURFACE...HIGH PRESSURE RIDGE AXIS REMAINS SQUEEZED OVER THE
UPPER MIDWEST AND 24-HR PRESSURE/TEMPERATURE CHANGES ARE MINIMAL.
JUST A UPWARD NUDGE COMPARED TO YESTERDAY.
QUIET CONDITIONS LOOK TO PREVAIL INTO SATURDAY AS WEAK UPPER RIDGING
BUILDS INTO THE AREA DOWNSTREAM OF THE DEVELOPING TROUGH TO THE
WEST. ANOTHER CHILLY NIGHT ON TAP...THOUGH NOT AS COLD AS RECENT
NIGHTS AS THE AIRMASS CONTINUES TO BE MODIFIED. CLOUD TRENDS HAVE
BEEN TRICKY AS DRIER AIRMASS AS OBSERVED BY 22.12Z MPX/GRB/DVN
SOUNDINGS IS ERODING ANY EASTWARD PROGRESS OF HIGH LEVEL CLOUDS.
HAVE KEPT MOSTLY CLEAR SKIES AT LEAST THROUGH 03-06Z FOR MUCH OF
THE AREA. HOWEVER...500-700MB WARM AIR ADVECTION SATURDAY SHOULD BE
ENOUGH TO SPREAD MID/HIGH CLOUDS ACROSS THE AREA FROM THE SOUTHWEST.
HIGHS WERE NUDGED DOWN A FEW DEGREES TO REMOVE SOME OF THE LATE
MARCH CLIMATOLOGY BIAS...BUT LOW TO MID 30S STILL LOOK REASONABLE.
THE WEEKEND STORM SYSTEM THAT YESTERDAY WAS AIMING TO TRACK SOUTH
HAS NOW BECOME SLIGHTLY MORE INTERESTING FOR PARTS OF THE FORECAST
AREA AS THERE HAS BEEN A SHIFT BACK TO THE NORTH. OVERALL...THE MID
TO UPPER LEVEL SUPPORT HAS IMPROVED THANKS TO A STRONGER NORTHERN
STREAM SHORTWAVE...AND SOME IMPRESSIVE LIFT DYNAMICS. ALTHOUGH THE
BULK OF THE FORCING DOES REMAIN TO OUR SOUTH...THERE ARE A FEW
THINGS TO BE NOTED. FIRST...THE AREA IS FAVORABLY LOCATED IN THE
LEFT EXIT REGION OF THE 250MB JET PROVIDING DECENT DIVERGENCE ALOFT.
AS THE SYSTEM EJECTS INTO THE CENTRAL PLAINS AND MID MISSISSIPPI
RIVER VALLEY...BROAD BUT VERY PERSISTENT 280-290K ISENTROPIC LIFT IS
PRESENT SOUTH OF I-90 AND THERE IS A 6 TO 12 HOUR TIME FRAME SUNDAY
MORNING AND AFTERNOON WITH DECENT MID LEVEL WARM AIR ADVECTION. VERY
WEAK 700MB FRONTOGENESIS IS SEEN ACROSS NORTHEAST IOWA AND FAR
SOUTHERN WISCONSIN AS WELL. FINALLY...THE MODEL GUIDANCE SHOWS A
BRIEF PERIOD OF 500-300MB PV ADVECTION. ALL OF THE ABOVE POINT TO A
PERIOD OF LIGHT BUT ACCUMULATING SNOW...HOWEVER...THE BIGGEST
NEGATIVELY COMPETING FACTOR WILL BE THE STRONG NORTHEASTERLY FEED OF
VERY DRY AIR RESULTING IN SATURATION ISSUES...ESPECIALLY IN THE
AREAS WHERE THE FORCING IS GREATEST. THE SATURATION PROBLEMS WILL
EVAPORATE A LOT OF PRECIPITATION EARLY ON...LIMITING POTENTIAL
ACCUMULATIONS.
REGARDING POTENTIAL SNOWFALL AMOUNTS...MODEL GUIDANCE CAME IN WITH
MORE QPF...WITH THE 22.09Z SREF PLUMES SHOWING A MEAN OF 4 INCHES AT
KDBQ. THE SPREAD VARIES FROM SEVERAL MEMBERS AT ONLY AT A
TRACE...THEN A FEW GREATER THAN 8 INCHES. THAT TREND IS SEEN ACROSS
THE AREA...BUT TO A LESSER DEGREE AT KDEH...KLSE...KRST. COBB OUTPUT
FROM 22.12Z NAM VARIED FROM LESS THAN AN INCH ALONG I-90...TO AROUND
6 INCHES AT KDBQ...AND 4 TO 5 INCHES AT KMCW AND KALO. HOWEVER...NOT
CONFIDENT ENOUGH TO MOVE COMPLETELY IN THAT DIRECTION GIVEN
AFOREMENTIONED DRY AIR / SATURATION ISSUES. ATTEMPTED TO CUT MODEL
QPF BY 1/3 TO ACCOUNT FOR THIS AND THIS TRANSLATES INTO AROUND 2
INCHES POSSIBLE ACROSS NORTHEAST IOWA AND FAR SOUTHWEST
WISCONSIN...THEN A TRACE TO MAYBE 1 INCH ALONG THE I-90 CORRIDOR
FROM PRE-SUNRISE SUNDAY THROUGH SUNDAY NIGHT.
IN SHORT...CONFIDENCE IN LIGHT BUT ACCUMULATING SNOWFALL SUNDAY /
SUNDAY EVENING HAS GROWN FOR THE SOUTHERN PORTIONS OF THE AREA WITH
FLURRIES OR OCCASIONAL LIGHT SNOW FOR ALONG AND JUST SOUTH OF I-90.
HAVE INCREASED PRECIPITATION CHANCES FOR THESE AREAS.
.LONG TERM...MONDAY THROUGH FRIDAY
310 PM CDT FRI MAR 22 2013
IN THE WAKE OF THE SUNDAY/SUNDAY NIGHT STORM SYSTEM...A REINFORCING
SHOT OF COLDER AIR LOOKS TO FOLLOW FOR MONDAY INTO MUCH OF NEXT
WEEK. CLIMATE PREDICTION CENTER FORECASTS THE ATLANTIC OSCILLATION
TO REMAIN NEGATIVE THROUGH AT LEAST APRIL 1ST...WHICH SUPPORTS OUR
STRETCH OF UNSEASONABLY COLD TEMPERATURES. THE LATEST CFS
TEMPERATURE ANOMALIES SHOW BELOW NORMAL TEMPERATURES EVEN INTO MID
APRIL POSSIBLY. LONGWAVE TROUGHING CONTINUES ACROSS THE EASTERN HALF
OF THE CONUS...WITH A WESTERN UPPER LEVEL RIDGE DEVELOPING BY THE
END OF NEXT WEEK. 850MB STANDARDIZED ANOMALIES VARY FROM -0.5 TO
-1.5 EACH DAY NEXT WEEK...GIVING HIGHS IN THE LOWER TO MID 30S AND
OVERNIGHT LOWS IN THE TEENS. TO HELP TREND THE FORECAST
BETTER...HAVE COOLED HIGHS/LOWS EACH DAY TO REMOVE CLIMATOLOGY BIAS
IN THE MODEL CONSENSUS THAT IS BEING INTRODUCED. THE THEME OF DRY
BUT COLD CONTINUES...WITH NO STORM SYSTEMS ON THE HORIZON UNTIL NEXT
WEEKEND POSSIBLY.
&&
.AVIATION...THROUGH 18Z SATURDAY
1253 PM CDT FRI MAR 22 2013
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. HIGH
PRESSURE WILL REMAIN OVER THE UPPER MISSISSIPPI RIVER VALLEY
THROUGH SATURDAY AFTERNOON PROVIDING QUIET WEATHER. CIRRUS IS
EXPECTED TO SPREAD FROM WEST TO EAST ACROSS THE AREA LATE THIS
EVENING THROUGH THE OVERNIGHT HOURS AS A TROUGH MOVES INTO THE
CENTRAL PLAINS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
310 PM CDT FRI MAR 22 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM...ZT
AVIATION...WETENKAMP