Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/17/13
AREA FORECAST DISCUSSION
NWS EUREKA CA...UPDATED
745 PM PDT SAT MAR 16 2013
.SYNOPSIS...
A WEAKENING FRONT WILL LIMP INTO NORTHWEST CALIFORNIA THIS EVENING
BRINGING A FEW SHOWERS NORTH OF CAPE MENDOCINO. THE NEXT CHANCE OF
RAIN WILL NOT BE UNTIL TUESDAY WHEN A MORE SUBSTANTIAL FRONT WILL
APPROACH.
&&
.EVENING UPDATE...RAIN HAS BEEN VERY LIMITED ACROSS DEL NORTE AND
NORTHERN HUMBOLDT COUNTIES THIS EVENING. HAVE OPTED TO LOWER POPS
FOR THE REST OF THE EVENING AS THE RAP MODEL HAS PULLED
PRECIPITATION BACK. THE 00Z NAM CONTINUES TO SHOW A SIGNIFICANT
AMOUNT OF PRECIP, BUT THE INITIALIZATION IS VERY POOR. LOOKING AT
THE HRRR FROM ESRL, IT IS ALSO SHOWING VERY LIMITED PRECIP ACROSS NW
CALIFORNIA THIS EVENING. WHILE THERE MAY BE A FEW SPRINKLES, DO NOT
THINK THERE WILL MUCH IN THE WAY OF MEASURABLE QPF. BFG
.PREV DISCUSSION...
SOME LIGHT RAIN IS FINALLY BEING REPORTED AROUND CRESCENT CITY WITH
THE COLD FRONT PASSING CAPE BLANCO THIS HOUR. SATELLITE AND RADAR
RETURNS ARE LOOKING EVEN LESS IMPRESSIVE THAN THEY DID EARLIER TODAY
AND WE DONT EXPECT MORE THAN A FEW HUNDREDTHS OF AN INCH OF
RAINFALL. MAY HAVE SOME SHOWERS LINGERING OVER THE SISKIYOUS
OVERNIGHT OTHERWISE MOST AREAS WILL BE DRY AFTER MIDNIGHT. LOW
LEVEL MOISTURE WILL LINGER INTO SUNDAY MORNING WHILE HIGH PRESSURE
BUILDS EASTWARD INTO OREGON...RESULTING IN CLEARING SKIES AS DRIER
AIR PUSHES IN FROM THE NORTH. CLEAR SKIES AND LIGHT WINDS EXPECTED
FOR MONDAY MORNING WILL ALLOW TEMPERATURES TO DROP THROUGH THE 30S
EVEN ALONG THE COAST. KEPT PATCHY FROST IN THE FORECAST AND WILL
NEED TO CONSIDER A FROST ADVISORY WITH THE OVERNIGHT OR SUNDAY
DAYTIME SHIFT. OTHERWISE QUIET WEATHER WILL LAST INTO MONDAY
BEFORE A MORE SUBSTANTIAL STORM SYSTEM APPROACHES. RIDGE AXIS WILL
PASS BY EARLY ON TUESDAY BEFORE A DEEPENING TROUGH REACHES THE
COAST BY WEDNESDAY. MODELS ARE COMING INTO BETTER AGREEMENT ON
TIMING...WITH THE BULK OF THE RAINFALL EXPECTED AHEAD AND ALONG A
COLD FRONT TUESDAY NIGHT. BULK OF THE GUIDANCE IS INDICATING
FAIRLY WIDESPREAD WARM SHOWERS IN WARM ADVECTION ON TUESDAY.
THAT SAID AMOUNTS AND COVERAGE ARE QUESTIONABLE SO KEPT MOSTLY
CHC POPS UNTIL TUE NT. COLD UPPER TROUGH PASSING BY WEDNESDAY
NIGHT WILL KEEP RAIN SHOWERS GOING BUT COLDEST AIR ALOFT AND SUB-
6000FT SNOW LEVELS WILL NOT ARRIVE UNTIL WEDNESDAY NIGHT...AFTER
THE BULK OF THE MOISTURE AND FORCING HAS SHIFTED EAST OF NW
CALIFORNIA. LARGE RIDGE OF HIGH PRESSURE WILL BUILD BACK ACROSS
THE ERN PACIFIC AND CALIFORNIA FOR THE END OF THE UPCOMING WEEK.
WASNT COMPLETELY CONFIDENT ON TIMING SO LEFT LOW CHC POPS WED
NT/THU AM BUT IF CURRENT GUIDANCE WORKS OUT WE WILL BE HIGH AND
DRY BY THAT TIME. AAD
&&
.AVIATION...A WEAK COLD FRONT WILL BRING LIGHT RAIN TO COASTAL AREAS
OF DEL NORTE AND HUMBOLDT COUNTIES THIS EVENING AND TONIGHT. CIGS
MAY FALL INTO IFR LATER TONIGHT BRIEFLY AROUND THE COLD FRONT BEFORE
DRIER AIR FILTERS INTO THE REGION. FARTHER INLAND VFR SHOULD PERSIST
OVERNIGHT THROUGH SUNDAY APART FROM SOME PATCHY VALLEY FOG
OVERNIGHT. RPA
&&
.MARINE...NORTHERLY WINDS WILL DECREASE OVERNIGHT AS A WEAK COLD
FRONT MOVES THROUGH THE WATERS ALLOWING THE SMALL CRAFT ADVISORIES
TO EXPIRE THIS EVENING. WINDS WILL INCREASE AGAIN ON SUNDAY AS HIGH
PRESSURE BUILDS BACK OVER THE EASTERN PACIFIC STRENGTHENING THE
PRESSURE GRADIENT. SCA CONDITIONS WILL LIKELY DEVELOP ACROSS BOTH
OUTER WATER ZONES INTO MONDAY AND MAY STRETCH INTO THE INNER WATERS
AS WELL. A SIGNIFICANT LOW PRESSURE SYSTEM WILL BEGIN TO MOVE ITS
WAY TOWARD THE COAST MONDAY INTO TUESDAY PUSHING THE AREA OF HIGH
PRESSURE OFF TO THE EAST. WINDS WILL QUICKLY SWITCH AROUND TO OUT OF
THE SOUTH ON TUESDAY AND RAMP UP TO NEAR GALE TUESDAY NIGHT INTO
WEDNESDAY MORNING. SEAS WILL BUILD IN RESPONSE TO THE
WINDS...PEAKING BETWEEN 10 AND 12 FEET. A SECONDARY STORM WILL ALSO
DEVELOP SOUTH OF ALASKA PUSHING A NORTHWEST SWELL TOWARD THE COAST
WEDNESDAY INTO THURSDAY. BY THURSDAY HIGH PRESSURE WILL BUILD BACK
OVER THE EASTERN PACIFIC AS THE LOW PRESSURE SYSTEM MOVES INLAND.
THIS WILL TURN THE WINDS BACK OUT OF THE NORTH ONCE AGAIN FOR MID TO
LATE NEXT WEEK. SEAS MAY BUILD BACK OVER 10 FT...AFTER A SHORT
PERIOD OF SMALLER SEAS...ACROSS THE OUTER AND SOUTHERN WATERS AS THE
NORTHERLIES INTENSIFY AND THE SWELL MOVES THROUGH THE WATERS. RPA
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY UNTIL 9 PM PDT THIS EVENING PZZ455-475.
&&
$$
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AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
314 PM MDT FRI MAR 15 2013
.SHORT TERM...
WINDS HAVE BEEN A CHALLENGE TODAY WITH ALL KINDS OF SHIFTING
DIRECTIONS AT SOME OF THE AIRPORTS ALTHOUGH THE IDEA OF MORE
GENERAL WNW TO NW WINDS MOVING OFF THE FOOTHILLS ONTO THE PLAINS
WAS NICELY SHOWN IN EARLIER RUNS OF THE HRRR THOUGH TIMING WAS OFF
A TAD. OTHERWISE DESPITE THE EARLIER CLOUDINESS TEMPERATURES
WARMED SMARTLY TODAY AND DENVER DID INDEAD GET THE RECORD
HIGH...HITTING 76 TO BREAK THE OLD RECORD OF 75 DATING WAY BACK TO
1877. A DIFFERENT DAY IN STORE FOR SATURDAY AS A WEAK FRONT PUSHES
SOUTH OVERNIGHT ACROSS THE PLAINS AND COMBINES WITH A WEAK UPPER
LEVEL SYSTEM ASSOCIATED WITH A JET STREAK IN THE ZONAL FLOW. ALL
IN ALL THIS SYSTEM IS NOT STRAIGHTFORWARD AND CONFIDENCE IN HOW
MUCH PRECIPITATION WE GET FOR THE PLAINS IS RATHER LOW EVEN THOUGH
IT IS ONLY A DAY AHEAD. THE MODELS HAVE BEEN EXUBERANT IN
PRODUCING QUITE A MAXIMUM OF OVER A HALF INCH MELTED EAST OF
DENVER WHERE THEY PREDICT SOME FAIRLY STRONG 700 MB FRONTOGENESIS
AND CONVERGENT WINDS. SOME OF THE RUNS WERE A LITTLE HIGH ON THE
LOWER LEVEL DEWPOINTS WHICH MIGHT EXPLAIN THE HEAVIER
PRECIPITATION AMOUNTS. TOUGH CALL BUT KEPT THE LIKELY POPS ON
PORTIONS OF THE PLAINS WITH TEMPERATURES IN THE 40S FOR HIGHS ON
SATURDAY. COULD EASILY SEE THERE BEING LESS PRECIP...WHILE IF THE
COLD AIR UP IN NEBRASKA COMES DOWN A LITTLE MORE AND PRECIP IS
HEAVIER COULD ALSO SEE IT MIXING WITH OR CHANGING TO SNOW ON
PORTIONS OF THE PLAINS. IN THE MOUNTAINS THE PRECIPITATION SHOULD
BE FAIRLY CONVECTIVE IN GENERALLY ZONAL FLOW SO MODEST AND LIKELY
HIGHLY VARYING SNOW AMOUNTS ARE EXPECTED THROUGH SATURDAY.
.LONG TERM...
SHOWERS ASSOCIATED WITH THE WEAK UPPER LEVEL DISTURBANCE AND
BEHIND THE COLD FRONT WILL GRADUALLY DECREASE FROM WEST TO EAST
SATURDAY NIGHT. MODEL SOUNDINGS ARE SHOWING CLOSE TO FREEZING
TEMPERATURES NEAR THE SURFACE SATURDAY NIGHT SO THERE COULD BE A
MIXTURE OF RAIN AND SNOW SHOWERS OVER THE PLAINS SATURDAY NIGHT.
FOR THE MOUNTAINS SNOW SHOWERS COULD LINGER INTO THE EARLY HOURS
ON SUNDAY MORNING.
ON SUNDAY A FAST MOVING SHORTWAVE TROUGH WILL MOVE OVER THE
WESTERN SLOPES DURING THE LATE MORNING TIME AND MOVE OVER HIGHER
TERRAIN DURING THE AFTERNOON. STRONG NORTHWEST FLOW ALOFT AND GOOD
LIFT WILL AID SNOW IN THE MOUNTAINS...WITH A GOOD CHANCE OF
2 TO 5 INCH ACCUMULATIONS. ON THE PLAINS...CANT RULE OUT A BRIEF
SHOWER WITH THE PASSAGE OF THE UPPER LEVEL DISTURBANCE AS THERE
MAY BE ENOUGH INSTABILITY TO BRIEFLY OFFSET THE STRENGTHENING
DOWNSLOPE. ON THE FAR EASTERN PLAINS...VARIOUS MODELS INDICATE
SOME CAPE VALUES LESS THAN 500 J/KG...THEREFORE HAVE INTRODUCED A
SLIGHT CHANCE OF THUNDER IN THE FAR NORTHEASTERN PLAINS SUNDAY
AFTERNOON. COLD FRONTAL PASSAGE WILL PRODUCE STRONG DOWNSLOPE
WINDS UP TO 50 MPH SUNDAY EVENING INTO MONDAY MORNING.
NORTHWEST FLOW WILL CONTINUE INTO MONDAY AS THE JET EXITS AND
RIDGING BUILDS IN. TEMPERATURES WILL BE BELOW NORMAL ON MONDAY
WITH DRY CONDITIONS RETURNING TO THE REGION...AND RETURN TO NEAR
NORMAL TEMPERATURES BY TUESDAY. A STRONG LOW PRESSURE SYSTEM WILL
MOVE INTO THE NORTHWESTERN STATES TUESDAY EVENING AND CONTINUES TO
DIG INTO THE REGION ON WEDNESDAY. THE STRENGTH AND TRACK OF THE
SYSTEM IS STILL BEING ANALYZED BUT SHOULD BRING SOME PRECIPITATION
TO THE AREA WEDNESDAY NIGHT WITH THE ABILITY TO CONTINUE THROUGH
FRIDAY EVENING.
&&
.AVIATION...
WINDS HAVE BEEN TROUBLING BUT FINALLY SEEING THE WNW FLOW WORKING
ACROSS MOST OF THE AREA AFTER SOME INTERESTING VARIATIONS EARLIER.
WOULD EXPECT THESE WINDS TO DIMINISH AFTER DARK AT LEAST SOMEWHAT.
THEN A SHIFT TO NORTHEAST STILL LOOKS ON TRACK NEAR MIDNIGHT AT
DIA AS IT LOOKS NOW. WINDS ARE LIKELY TO COME AROUND TO SE ON
SATURDAY WHICH COULD LEAD TO AT LEAST A WEAK DENVER CYCLONE WITH A
MORE NE DIRECTION AT DIA.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SZOKE
LONG TERM....BOWEN
AVIATION...SZOKE
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
945 PM EDT SAT MAR 16 2013
.UPDATE...
HAVE MADE SEVERAL MINOR TWEAKS TO THE FORECAST...MAINLY TO SKY
COVER AS PART OF THE 00Z TAF ISSUANCE. BOTH HRRR AND LOCAL WRF
KEEP ALL RAIN NORTH OF THE AREA TONIGHT SO REMOVED POPS FROM
EXTREME NORTH GEORGIA AND ADDED A LITTLE FOG WORDING IN AS
WELL...WITH LOW CLOUDS MOVING IN SUNDAY MORNING EXPECT SOME PATCHY
FOG TO DEVELOP. NO MAJOR CHANGE TO TEMPS EXCEPT FOR MINOR TWEAKS
TO UPDATE FOR TRENDS. UPDATED PRODUCTS WILL BE OUT SHORTLY.
TDP
&&
.PREV DISCUSSION... /ISSUED 833 PM EDT SAT MAR 16 2013/
PREV DISCUSSION... /ISSUED 340 PM EDT SAT MAR 16 2013/
SHORT TERM /TONIGHT THROUGH SUNDAY/...
CURRENT SATELLITE LOOP SHOWS MOSTLY CLEAR SKIES ACROSS NORTH AND
CENTRAL GEORGIA. SURFACE HIGH PRESSURE WILL CONTINUE TO PERSIST
THROUGH THE WEEKEND...WITH WARMING ABOVE NORMAL TEMPERATURES
CONTINUING TODAY AND SUNDAY. EXPECT HIGH TEMPERATURES IN THE LOW TO
MID 70S...AND LOWS IN THE UPPER 40S AND LOW 50S. THE MODELS ARE IN
DECENT AGREEMENT AND FAIRLY CONSISTENT WITH WEAK FRONTAL BOUNDARY
SAGGING INTO THE TENNESSEE VALLEY TODAY. THIS FRONTAL BOUNDARY
SHOULD INCREASE CLOUD COVER ESPECIALLY ACROSS NORTH GA SUN AND MAY
EVEN SEE SOME ISOLATED SHOWERS SUN AFTERNOON ALSO. THE MODELS ARE
ALSO SHOWING A WEAK DISTURBANCE MOVING NORTHWARD INTO THE REGION
FROM THE GULF OF MEXICO WHICH WILL BRING ADDITIONAL MOISTURE INTO THE
AREA SUNDAY AFTERNOON INTO SUN NIGHT FOR NOW...HAVE INDICATED INCREASED
CLOUD COVER ACROSS CENTRAL GEORGIA AS A RESULT...AND ANY RESULTING
RAINFALL SHOULD STAY SOUTH OF THE CWA.
01
LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
WARM FRONT/STALLED FRONTAL BOUNDARY REMAINS ACROSS THE GA/TN BORDER
ON SUNDAY NIGHT. BOTH THE NAM AND GFS ARE PICKING UP ON A SHORTWAVE
MOVING NORTH IN THE SW FLOW FROM THE GULF OF MEXICO SUNDAY NIGHT.
BOTH MODELS PRODUCE PRECIP WITH THIS FEATURE...BUT THE NAM IS
FURTHER SOUTH WITH ITS BULLSEYE. WILL END UP ADDING SOME LOW END
CHANCE POPS FOR SHOWERS IN THE SW PORTION OF THE CWFA SUNDAY
EVENING.
A COLD FRONT IS STILL PROGGED TO MOVE THROUGH THE CWFA ON MONDAY
INTO EARLY TUESDAY. THE MAIN MID LEVEL FORCING WITH THIS SYSTEM
REMAINS WELL TO THE NORTH...BUT THERE WILL BE SOME LIFT/FORCING
ALONG THE FRONT. SURFACE INSTABILITY WILL SPREAD AHEAD OF THE FRONT
MONDAY AFTERNOON AND EVENING...ALONG WITH SOME DECENT SHEAR.
ISOLD/SCT SEVERE STORMS ARE POSSIBLE. BOTH THE NAM AND GFS ARE ALSO
SETTING UP A COOL AIR WEDGE ACROSS THE NE CWFA SUNDAY NIGHT INTO
MONDAY. AREAS IN THE WEDGE WILL STAY MORE STABLE. HOWEVER...ALONG
THE WEDGE FRONT...LOCALIZED HIGH SRH MAY BE ENHANCED.
THE COLD FRONT MAY HANG UP ACROSS THE SOUTHERN CWFA...BUT SHOULD
CLEAR THE AREA BY EARLY TUESDAY MORNING. HAVE TRIED TO ARRANGE POPS
ACCORDINGLY.
MID LEVEL FLOW REMAINS ZONAL FOR THE REMAINDER OF THE LONG TERM
PERIOD. SEVERAL FAST MOVING PIECES OF S/W ENERGY ARE PROGGED TO MOVE
THROUGH THE ATMOS...EACH TRIGGERING CLOUDS/SMALL POPS.
NLISTEMAA
AVIATION...
00Z UPDATE...
VFR OVERNIGHT WITH MVFR CIGS MOVING IN AROUND 11Z SUNDAY...LIFTING
TO BKN VFR AROUND 16Z OR SO. CIGS SHOULD REMAIN VFR THROUGH THE
DAY UNTIL AFTER 00Z MONDAY WHEN MVFR CIGS MOVE IN AGAIN. WINDS
GENERALLY SW THROUGH THE PERIOD BUT FOR ATLANTA WILL BRIEFLY GO
SE AS THE MVFR CIGS COME IN 02Z-03Z MONDAY.
//ATL CONFIDENCE...00Z UPDATE...
MEDIUM ON TIMING OF CIGS AND CIG HEIGHTS.
HIGH ON ALL OTHER ELEMENTS.
TDP
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 50 77 55 72 / 5 20 30 50
ATLANTA 52 73 58 71 / 5 20 30 60
BLAIRSVILLE 46 70 51 62 / 20 20 30 70
CARTERSVILLE 48 74 55 71 / 5 20 30 70
COLUMBUS 51 76 59 75 / 5 10 30 50
GAINESVILLE 50 73 55 66 / 5 20 30 60
MACON 48 76 55 74 / 5 10 30 50
ROME 47 74 56 71 / 10 20 40 70
PEACHTREE CITY 47 74 54 72 / 5 10 30 60
VIDALIA 53 78 55 78 / 5 10 20 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
106 AM CDT FRI MAR 15 2013
.DISCUSSION...
822 PM CDT
ONLY MADE A FEW MINOR TWEAKS TO GOING FORECAST...MAINLY TO END
PRECIP AN HOUR OR TWO AGO WITH PREVIOUS GRID/ZFP UPDATE...AND
CURRENTLY TO TWEAK SKY COVER A BIT PER SATELLITE TRENDS AND TO ADD
MENTION OF SOME PATCHY FOG ACROSS THE FORECAST AREA OVERNIGHT.
MID-LEVEL SHORT WAVE THAT PRODUCED LIGHT PRECIPITATION IN SOME PARTS
OF THE CWA DURING THE DAY WAS DIGGING SOUTHEAST ACROSS THE LOWER
OHIO VALLEY THIS EVENING. RADAR INDICATES PRECIPITATION HAS SHIFTED
WELL SOUTHEAST OF THE CWA...WITH SOME LINGERING LOW CLOUDINESS STILL
NOTED ACROSS THE CENTRAL/SOUTHEAST COUNTIES PER 11-3.9 MICRON GOES
IR IMAGERY. MODEL GUIDANCE DEPICTS MODEST HEIGHT RISES/SUBSIDENCE
SPREADING SOUTHEAST ACROSS IL IN THE WAKE OF THE DEPARTING UPPER
TROUGH...LIKELY HELPING TO MAINTAIN INVERSION SEEN JUST ABOVE 900 MB
IN DVN/ILX 00Z SOUNDINGS. SHORT WAVE HAS OUTRUN WEAKENING SURFACE
LOW PRESSURE OVER MISSOURI...WITH WEAK SFC RIDGE TO THE NORTHEAST
ACROSS WI/NE IL AND INDIANA. RESULTING DISORGANIZED LOW LEVEL WIND
FIELD NOT PROVIDING MUCH IN THE WAY OF DRYING...WITH SFC DEW POINT
TEMPS HOLDING IN THE UPPER 20S/LOW 30S. FORECAST SOUNDINGS FROM 18Z
NAM/ARW AND THE LAST SEVERAL RAP RUNS INDICATE SATURATION OF THE
SHALLOW BOUNDARY LAYER OVERNIGHT...THOUGH FAIRLY PREVALENT THIN HIGH
CIRRUS AND 25 KT WINDS JUST ATOP THE BOUNDARY LAYER WILL LIKELY
PREVENT SIGNIFICANT PATCHES OF DENSE FOG. STILL...T-TD DEPRESSIONS
LESS THAN 3 DEGREES IN MANY SPOTS ALREADY WHICH ALL COMBINES TO
SUGGEST THE POTENTIAL FOR AT LEAST SOME PATCHY SHALLOW FOG
OVERNIGHT. HAVE ADDED A MENTION BEYOND 03Z FOR MOST OF THE CWA SAVE
THE WARMER CLOSE-IN URBAN CORE OF CHICAGO.
OTHERWISE...INHERITED GRIDS/FORECAST APPEAR TO BE IN PRETTY GOOD
SHAPE AND HAVE MADE NO OTHER SIGNIFICANT CHANGES TO THE GOING
FORECAST.
RATZER
//PREV DISCUSSION...
300 PM CDT
TONIGHT...FORECAST CONFIDENCE HIGH.
AN AREA OF SNOW MOVING SOUTHEAST ACROSS MOST OF THE FORECAST AREA IS
ASSOCIATED WITH A FAST-MOVING 500MB SHORTWAVE. THE DRY AIR OVER THE
LAKE IS KEEPING THE SNOW JUST TO THE WEST AND SOUTH OF THE CHICAGO
METRO AREA. THAT SNOW WILL FALL MORE AS RAIN AS IT MOVES FURTHER
SOUTH INTO THE WARMER SURFACE TEMPS. LOOK FOR THE SHORTWAVE TO EXIT
SOUTH CENTRAL IL BY 00Z THIS EVENING.
DRY FORECAST TONIGHT WITH CLOUDS DECREASING. THIS WILL ALLOW TEMPS
TO DIP DOWN INTO THE 25 TO 30F RANGE. THE 925MB BAROCLINIC ZONE WILL
REMAIN FAIRLY STATIONARY ACROSS THE WI/IL BORDER.
FRIDAY...FORECAST CONFIDENCE MEDIUM.
ANOTHER 500MB SHORTWAVE WILL TRACK ALONG THE 850MB BAROCLINIC ZONE
ON FRIDAY WHICH WILL BE SOMEWHERE BETWEEN FAR NORTHERN IL AND
CENTRAL WI...DEPENDING ON THE MODEL. THE NAM CONTINUES TO HAVE THE
FURTHEST NORTH SOLUTION AND THE GFS IS FURTHEST SOUTH. THE LOCATION
OF THIS BAROCLINIC ZONE WILL HAVE A BIG IMPACT ON WHERE THE SOUTHERN
EDGE OF THE PRECIP WILL BE AND ALSO THE PRECIP TYPE.
RIGHT NOW IT LOOKS LIKE THE NORTHERN HALF OF THE FORECAST AREA WILL
HAVE THE BEST CHANCE OF BEING CLIPPED BY THE SOUTHERN EDGE OF THIS
SYSTEM. MOST OF THE MODELS FAVOR NORTHERN IL TO BE IN THE RAIN AREA
ALTHOUGH THERE IS SOME UNCERTAINTY AND A MIX OF RAIN AND SNOW COULD
BE POSSIBLE ESPECIALLY NEAR THE WI BORDER.
FRIDAY NIGHT AND SATURDAY...FORECAST CONFIDENCE IS MEDIUM.
A SECONDARY MID LEVEL SHORT WAVE WILL BE SLIDING SOUTHEAST ALONG
A LOWER LEVEL BAROCLINIC ZONE. THE SLIGHT BACKING OF THE LOW
LEVEL FLOW ACROSS THE TIGHT THERMAL GRADIENT WILL KICK IN SOME
DECENT ISENTROPIC LIFT AND SATURATION FOR CONTINUED PRECIP
CHANCES...OR A SECOND ROUND ANYWAY...THROUGH FRIDAY NIGHT.
HOWEVER...TEMPERATURES WILL BE COOLING AS THE ASSOCIATED SFC COLD
FRONT PUSHES SOUTH THROUGH THE FORECAST AREA. ANY ACCUMS ARE
EXPECTED TO BE AN INCH OR LESS AND LIMITED MAINLY TO NORTH OF A
CHICAGO TO DE KALB LINE. MORE OF A RAIN SNOW MIX ELSEWHERE WILL
LIMIT ANY SNOW ACCUMS.
SOME FLURRIES MAY LINGER INTO SATURDAY...BUT FOR THE MOST PART...
EXPECT DRY WEATHER BUT MOSTLY CLOUDY SKIES AND HIGHS ABOUT 10
DEGREES BELOW NORMAL.
.SATURDAY NIGHT AND SUNDAY...FORECAST CONFIDENCE IS HIGH.
QUIET BUT CONTINUED COLDER THAN NORMAL AS CANADIAN HIGH PRESSURE
SLIDES ACROSS THE GREAT LAKES. SOME RETURN FLOW WARM ADVECTION
COULD BRING A SMALL CHANCE OF RAIN TO AREAS SOUTH OF
KANKAKEE...MAINLY IN THE AFTERNOON ON SUNDAY.
.MONDAY...FORECAST CONFIDENCE IS MEDIUM.
THE ECMWF AND THE GFS ARE COMING INTO BETTER AGREEMENT WITH THE
SYSTEM FOR EARLY NEXT WEEK. A POTENT MID LEVEL SHORT WAVE DIGS
INTO THE NRN TIER OF THE U.S. BY MONDAY MORNING. THE RESULTANT LOW
LEVEL CYCLOGENESIS IS RAPID OVER THE NORTHERN PLAINS WITH A RATHER
ELONGATED SURFACE LOW/TROF STRETCHING FROM A MAIN LOW PRESSURE
CENTER OVER CENTRAL MINNESOTA TO A WEAKER SECONDARY LOW OVER THE
OHIO VALLEY BY MONDAY MORNING. THIS IS ALL LIFTING TO THE EAST
NORTHEAST DURING THE DAY. PRECIP IS LIKELY ON MONDAY WITH THE TYPE
IN QUESTION AS TEMPERATURES BEGIN COLD ENOUGH FOR SNOW OR A RAIN
SNOW MIX...BUT MODIFY QUICKLY AS THE WARMER AIR SURGES IN. THE WINTRY
MIX WILL TRANSITION TO MAINLY RAIN DURING THE MORNING. IMPACT
LOOKS MINIMAL GIVEN THE WARM LOOK TO THIS SYSTEM.
.TUESDAY THROUGH THURSDAY....FORECAST CONFIDENCE IS LOW TO MEDIUM.
HIGH PRESSURE BUILDS IN WITH COLDER AND DRY WEATHER FOR THE MIDDLE
OF NEXT WEEK. THE ECMWF AND THE GFS ARE AT COMPLETE ODDS FOR THE
POTENTIAL STORM SYSTEM TOWARD THE END OF NEXT WEEK. WHERE THE GFS
HAS A BIG LOW OVER THE MIDDLE OF THE GREAT LAKES ON FRIDAY...THE
ECMWF HAS A VERY STRONG HIGH PRESSURE SYSTEM.
MKX
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* LIGHT SOUTHWEST WINDS TURNING TO THE NORTHWEST THIS MORNING WITH
A PERIOD OF LIGHT AND VARIABLE WINDS BY MID/LATE
MORNING...BEFORE TURNING MORE NORTHEAST BY MID DAY.
* VFR CEILINGS GRADUALLY LOWERING TODAY...AND WITH CONDITIONS
BECOMING MVFR LATE THIS AFTERNOON AS RAIN MOVES OVERHEAD.
* MVFR CEILINGS LOWERING TONIGHT WITH IFR CEILINGS POSSIBLE BY THE
END OF THE FORECAST PERIOD...ALSO WITH ANOTHER CHANCE OF A
RAIN/SNOW MIX.
RODRIGUEZ
//DISCUSSION...UPDATED 06Z...
A RELATIVELY QUIET START TO THE FORECAST IS EXPECTED ACROSS THE
TERMINALS AND WILL CONTINUE THROUGH MOST OF THE DAY...ONLY
MONITORING PATCHY FOG THIS MORNING AND WIND DIRECTION TRENDS
THROUGH MID DAY. AN AREA OF LOW PRESSURE AND ASSOCIATED COLD FRONT
WILL DROP SOUTHEAST ACROSS THE REGION TODAY AND AS THIS OCCURS THE
CURRENT SOUTHWEST WINDS WILL SHIFT MORE NORTHWEST LATER THIS
MORNING. THE OVERALL PRESSURE FIELD APPEARS TO RELAX BY MID
MORNING WITH LIGHT AND VARIABLE CONDITIONS POSSIBLE FOR A
PERIOD...BEFORE WINDS TURN NORTHEAST OFF OF THE LAKE BY MID DAY
AND REMAINING THIS DIRECTION THROUGH THE REMAINDER OF THE FORECAST
PERIOD. ONLY MID/HIGH LEVEL CLOUD IS EXPECTED THROUGH MOST OF
TODAY BEFORE VFR CEILINGS CONTINUE TO LOWER INTO THE
AFTERNOON...WITH MVFR CONDITIONS IN LIGHT RAIN EXPECTED THIS
AFTERNOON INTO THE EARLY EVENING. CONDITIONS SHOULD REMAIN MVFR
BUT WITH CONDITIONS TO LIKELY CONTINUE TO WORSEN TOWARDS THE END
OF THE FORECAST PERIOD AS YET ANOTHER CHANCE FOR PRECIP WILL BE
POSSIBLE...BUT THIS TIME IN THE FORM OF A RAIN/SNOW MIX. HAVE
LOWERED CEILINGS MORE TOWARDS THE LOWER END OF THE MVFR SPECTRUM
BY THE END OF THE FORECAST PERIOD...BUT IT WOULD NOT BE OUT OF THE
QUESTION FOR IFR CEILINGS TO BE IN PLACE. WILL CONTINUE TO MONITOR
THIS POTENTIAL AND ADJUST FORECAST AS NEEDED.
RODRIGUEZ
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM HIGH CONFIDENCE WITH WIND SPEED/DIRECTION TRENDS TODAY.
* HIGH CONFIDENCE WITH CEILINGS THROUGH EARLY AFTERNOON...MEDIUM
CONFIDENCE WITH CEILING TRENDS LATER THIS AFTERNOON INTO
TONIGHT.
* MEDIUM CONFIDENCE WITH MVFR CEILINGS AND RAIN/SNOW MIX
TONIGHT...WITH LOW MEDIUM CONFIDENCE OF IFR CEILINGS.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY...VFR CHANCE OF MORNING FLURRIES.
SUNDAY...VFR.
MONDAY...MVFR. CHANCE OF RAIN OR SNOW.
TUESDAY AND WEDNESDAY...VFR.
PAW
&&
.MARINE...
300 PM CDT
A CLIPPER SYSTEM MOVING ACROSS SOUTHERN ONTARIO WILL BRING ELEVATED
SOUTHERLY WINDS TO THE NORTHERN LAKE MICHIGAN TONIGHT. WINDS WILL
SHIFT TO NORTH BEHIND THIS CLIPPER AND HIGHER WINDS WILL EXPAND DOWN
THE LAKE ON FRIDAY WITH PRECIPITATION CHANCES. WINDS WILL DIMINISH
ON SATURDAY AS HIGH PRESSURE BUILDS INTO THE GREAT LAKES REGION.
WINDS WILL INCREASE ONCE AGAIN ON MONDAY AS A LOW PRESSURE SYSTEM
APPROACHES FROM THE NORTHERN PLAINS. GALES MAY BE POSSIBLE WITH THIS
SYSTEM.
MKX
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
221 PM MDT FRI MAR 15 2013
.UPDATE...
ISSUED AT 1236 PM MDT FRI MAR 15 2013
VISIBLE SATELLITE SHOWS THE BACK EDGE OF THE HIGH CLOUDS IS NOW
OVER NORTHEAST COLORADO AND SOUTHWEST NEBRASKA. AT THE SURFACE A
TROUGH OF LOW PRESSURE WAS RUNNING ALMOST PARALLEL TO THE BACK EDGE
OF THE CLOUDS. BEHIND THE SURFACE TROUGH WIND GUSTS UP TO 30 MPH
WERE REPORT ALONG WITH RELATIVE HUMIDITIES OF 10 TO 15 PERCENT.
THE SURFACE TROUGH...CURRENTLY JUST EAST OF THE KS/CO
BORDER...WILL CONTINUE TO MOVE EAST THROUGH THE AFTERNOON. AFTER
SOME DISCUSSION WITHIN THE OFFICE...HAVE DECIDED TO NOT ISSUE A
FIRE WEATHER HIGHLIGHT SINCE BOTH THE CRITERIA AND THE DURATION OF
CRITERIA BEING MET WILL BE JUST ENOUGH TO WARRANT A HIGHLIGHT...AND
THE EAST PART OF THE AREA WILL LIKELY NOT MEET THE DURATION
CRITERIA BY THE TIME THE SURFACE TROUGH MOVES THROUGH LATE THIS
AFTERNOON. HAVE SENT OUT A SPECIAL WEATHER STATEMENT TO HIGHLIGHT
THE THREAT...BUT AGAIN WILL HOLD OFF ISSUING A HIGHLIGHT DUE TO
THE VERY MARGINAL NATURE OF THIS EVENT.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 233 AM MDT FRI MAR 15 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW NW FLOW IN PLACE ACROSS
THE INTERMOUNTAIN WEST AND CENTRAL PLAINS WITH A RIDGE CENTERED
OVER SOUTHERN ARIZONA. AT THE SURFACE SEVERAL WEAK SURFACE TROUGHS
ARE IN PLACE OVER NW KANSAS AND EASTERN COLORADO.
H5 RIDGE IS EXPECTED TO CONTINUE TO WEAKEN WITH NW FLOW BECOMING
WESTERLY THIS AFTERNOON. WITH DEEP WESTERLY/DOWNSLOPE FLOW IN PLACE
ACROSS THE PLAINS WE WILL CONTINUE TO SEE WAA THROUGH THIS
AFTERNOON. CURRENTLY EXPECT NEAR RECORD HIGHS IN THE 80S ACROSS
MUCH OF THE CWA WITH SEVERAL LOCATIONS EXPECTED TO AT LEAST TIE
DAILY RECORDS.
A BACK DOOR COLD FRONT WILL DROP SOUTH OVER THE NORTHERN PLAINS AND
THROUGH THE CWA SATURDAY. SEASONAL TEMPERATURES WILL RETURN TO THIS
WEEKEND WITH HIGHS IN THE UPPER 40S TO MID 50S (COOLEST NORTHEAST-
WARMEST SOUTHWEST) AND OVERNIGHT LOWS NEAR FREEZING.
GUIDANCE CONTINUES TO SHOW SOME LIGHT QPF IN PLACE LATE TONIGHT
AFTER 06Z IN THE NORTHWEST SPREADING SOUTHEAST. HOWEVER...MODEL
SOUNDINGS CONTINUE TO SHOW A DRY LAYER BELOW 600MB THROUGH
SATURDAY MORNING...SO IM SKEPTICAL WHETHER WE WILL SEE MEASURABLE
TONIGHT. I LEFT 20 POPS IN PLACE TO ACCOUNT FOR POTENTIAL. BETTER
CHANCES SHOULD BE LATER IN THE DAY SATURDAY THROUGH SATURDAY NIGHT
AS LARGE SCALE FORCING AND WEAK INSTABILITY OVERSPREAD THE
REGION...WHEN A SHORTWAVE TROUGH MOVES ACROSS THE CENTRAL ROCKIES.
I INCREASE POPS TO LIKELY CATEGORY AROUND 00Z SAT THROUGH SAT
EVENING...WITH A DECREASING IN COVERAGE AFTER 06Z. A SECOND
STRONGER SHORTWAVE TROUGH WILL PASS THROUGH THE REGION
SUNDAY...WITH PRECIP CHANCES INCREASING ONCE AGAIN SUNDAY
AFTERNOON AND EVENING...BEFORE TAPERING OFF LATE SUNDAY NIGHT.
WITH TEMP PROFILES GENERALLY WARM THROUGH THE PERIOD WE SHOULD
MAINLY SEE RAIN AS THE PREDOMINATE PRECIP TYPE...THOUGH EARLY
SUNDAY MORNING AND LATE SUNDAY NIGHT WE COULD SEE A RAIN/SNOW
CHANGE OVER AND LIGHT SNOW ACCUMULATIONS. WITH WARM GROUND
TEMPERATURES AND THE BRIEF NATURE OF ANY CHANGE OVER...I AM NOT
SURE HOW MUCH SNOW ACCUMULATION WE WOULD ACTUALLY SEE. FOR NOW I
HAVE AROUND ONE HALF INCH OF LESS IN THE FORECAST FOR SAT
NIGHT...WITH ONLY A TRACE OF ACCUMULATION SUNDAY NIGHT.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 220 PM MDT FRI MAR 15 2013
SATURDAY NIGHT...500 MB SHORT WAVE TROUGH WILL MOVE ACROSS THE AREA.
GEOSTROPHIC FORCING PER LAYER Q VECTOR CONVERGENCE IS NOT GREAT...
BUT ADEQUATE ENOUGH FOR UPWARD VERTICAL MOTION. FRONTOGENETIC
FORCING IS ALSO LACKING IN THE LOW LEVELS...THOUGH IS A LITTLE
BETTER ABOVE 700 MB. THE CURRENT SET OF POPS SEEM A LITTLE
HIGH...BUT WILL ONLY TWEAK THEM DOWN A LITTLE FOR THE SAKE OF
CONSISTENCY.
THE PHASE OF PRECIPITATION IS PROBLEMATIC FROM 06Z-12Z. MODEL
SOUNDINGS SHOW A MIXED BAG OF DRIZZLE...LIGHT SNOW...AND LIGHT RAIN.
CANNOT RULE OUT A FEW HOURS OF FREEZING DRIZZLE ESPECIALLY IN THE
EASTERN HALF OF THE FORECAST AREA...BUT CONFIDENCE IS NOT HIGH
ENOUGH TO MENTION YET. FOR THE SAKE OF SIMPLICITY...WILL JUST FORECAST
PRECIPITATION TYPE AS A MIXTURE OF LIGHT SNOW/LIGHT RAIN. THERE IS
A POTENTIAL TO GET AN INCH OF SNOW WITH THE SYSTEM BY SUNDAY
MORNING.
SUNDAY...THE FIRST SHORTWAVE WILL MOVE EAST OF THE FORECAST
AREA...BUT ANOTHER WAVE WILL MOVE ACROSS EASTERN COLORADO BY THE
AFTERNOON. LOW LEVEL MOISTURE WILL BE LIMITED...BUT GFS DEPICTS AN
AN AREA OF MIXED LAYER CAPES AROUND 400 J/KG BY THE AFTERNOON.
THOUGH THE NAM IS NOT AS AGGRESSIVE WITH THE INSTABILITY...WILL
INTRODUCE A SLIGHT CHANCE OF THUNDERSTORMS OVER THE COLORADO
COUNTIES. ABUNDANT CLOUD COVER WILL KEEP TEMPERATURES IN THE UPPER
40S AND 50S.
MONDAY...A COLD FRONT WILL SWEEP ACROSS THE AREA EARLY IN THE
MORNING. WINDS BEHIND THE FRONT WILL BE STRONG...LIKELY 20 TO 30
KNOTS WITH GUSTS TO 40 KNOTS. EXPECT TEMPERATURES TO DROP 5-10
DEGREES FROM SUNDAY.
TUESDAY THROUGH WEDNESDAY...MID LEVEL RIDGE WILL KEEP PROVIDE
SLIGHTLY WARMER TEMPERATURES AND DRY WEATHER TO THE REGION.
WEDNESDAY NIGHT THROUGH FRIDAY...LONG RANGE MODELS DEVELOP A DEEP
TROUGH OVER THE WESTERN UNITED STATES. A SERIES OF SHORT WAVES
WILL BRING ENOUGH UPWARD VERTICAL MOTION ACROSS THE HIGH PLAINS TO
MENTION PRECIPITATION THROUGH THE PERIOD. LOW LEVEL MOISTURE WILL
BE SOMEWHAT LIMITED...BUT THERE IS ENOUGH MODEL CONSISTENCY TO
MENTION A CHANCE OF LIGHT RAIN OR SNOW.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1139 AM MDT FRI MAR 15 2013
VFR CONDITIONS FORECAST FOR THE 18Z TAFS. VISIBLE SATELLITE IS
SHOWING SOME CLEARING OVER WESTERN NEBRASKA WHICH IS ALLOWING
GUSTS UP TO 25 KTS TO DEVELOP. FORESEE THIS ALSO HAPPENING TO KMCK
THIS AFTERNOON AND POSSIBLY KGLD..ALTHOUGH THE CLOUDS MAY NOT
CLEAR FOR KGLD WHICH WILL HINDER THE GUSTS FROM DEVELOPING. THE
GUSTS WILL CEASE EARLY THIS EVENING AS TEMPERATURES COOL.
OVERNIGHT WINDS WILL BECOME LIGHT AND CHANGE TO THE NORTH AS A
COLD FRONT MOVES IN FROM THE NORTH. THE NORTHERLY WINDS WILL
CONTINUE UNTIL MID TO LATE SATURDAY MORNING WHEN THEY WILL TURN TO
MORE OF AN EASTERLY DIRECTION. PRECIPITATION CHANCES WILL INCREASE
FROM WEST TO EAST...BUT SHOULD REMAIN MAINLY WEST OF KGLD UNTIL
EARLY AFTERNOON.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JTL
SHORT TERM...DR
LONG TERM...MENTZER
AVIATION...JTL
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1246 PM MDT FRI MAR 15 2013
.UPDATE...
ISSUED AT 1236 PM MDT FRI MAR 15 2013
VISIBLE SATELLITE SHOWS THE BACK EDGE OF THE HIGH CLOUDS IS NOW
OVER NORTHEAST COLORADO AND SOUTHWEST NEBRASKA. AT THE SURFACE A
TROUGH OF LOW PRESSURE WAS RUNNING ALMOST PARALLEL TO THE BACK EDGE
OF THE CLOUDS. BEHIND THE SURFACE TROUGH WIND GUSTS UP TO 30 MPH
WERE REPORT ALONG WITH RELATIVE HUMIDITIES OF 10 TO 15 PERCENT.
THE SURFACE TROUGH...CURRENTLY JUST EAST OF THE KS/CO
BORDER...WILL CONTINUE TO MOVE EAST THROUGH THE AFTERNOON. AFTER
SOME DISCUSSION WITHIN THE OFFICE...HAVE DECIDED TO NOT ISSUE A
FIRE WEATHER HIGHLIGHT SINCE BOTH THE CRITERIA AND THE DURATION OF
CRITERIA BEING MET WILL BE JUST ENOUGH TO WARRANT A HIGHLIGHT...AND
THE EAST PART OF THE AREA WILL LIKELY NOT MEET THE DURATION
CRITERIA BY THE TIME THE SURFACE TROUGH MOVES THROUGH LATE THIS
AFTERNOON. HAVE SENT OUT A SPECIAL WEATHER STATEMENT TO HIGHLIGHT
THE THREAT...BUT AGAIN WILL HOLD OFF ISSUING A HIGHLIGHT DUE TO
THE VERY MARGINAL NATURE OF THIS EVENT.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 233 AM MDT FRI MAR 15 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW NW FLOW IN PLACE ACROSS
THE INTERMOUNTAIN WEST AND CENTRAL PLAINS WITH A RIDGE CENTERED
OVER SOUTHERN ARIZONA. AT THE SURFACE SEVERAL WEAK SURFACE TROUGHS
ARE IN PLACE OVER NW KANSAS AND EASTERN COLORADO.
H5 RIDGE IS EXPECTED TO CONTINUE TO WEAKEN WITH NW FLOW BECOMING
WESTERLY THIS AFTERNOON. WITH DEEP WESTERLY/DOWNSLOPE FLOW IN PLACE
ACROSS THE PLAINS WE WILL CONTINUE TO SEE WAA THROUGH THIS
AFTERNOON. CURRENTLY EXPECT NEAR RECORD HIGHS IN THE 80S ACROSS
MUCH OF THE CWA WITH SEVERAL LOCATIONS EXPECTED TO AT LEAST TIE
DAILY RECORDS.
A BACK DOOR COLD FRONT WILL DROP SOUTH OVER THE NORTHERN PLAINS AND
THROUGH THE CWA SATURDAY. SEASONAL TEMPERATURES WILL RETURN TO THIS
WEEKEND WITH HIGHS IN THE UPPER 40S TO MID 50S (COOLEST NORTHEAST-
WARMEST SOUTHWEST) AND OVERNIGHT LOWS NEAR FREEZING.
GUIDANCE CONTINUES TO SHOW SOME LIGHT QPF IN PLACE LATE TONIGHT
AFTER 06Z IN THE NORTHWEST SPREADING SOUTHEAST. HOWEVER...MODEL
SOUNDINGS CONTINUE TO SHOW A DRY LAYER BELOW 600MB THROUGH
SATURDAY MORNING...SO IM SKEPTICAL WHETHER WE WILL SEE MEASURABLE
TONIGHT. I LEFT 20 POPS IN PLACE TO ACCOUNT FOR POTENTIAL. BETTER
CHANCES SHOULD BE LATER IN THE DAY SATURDAY THROUGH SATURDAY NIGHT
AS LARGE SCALE FORCING AND WEAK INSTABILITY OVERSPREAD THE
REGION...WHEN A SHORTWAVE TROUGH MOVES ACROSS THE CENTRAL ROCKIES.
I INCREASE POPS TO LIKELY CATEGORY AROUND 00Z SAT THROUGH SAT
EVENING...WITH A DECREASING IN COVERAGE AFTER 06Z. A SECOND
STRONGER SHORTWAVE TROUGH WILL PASS THROUGH THE REGION
SUNDAY...WITH PRECIP CHANCES INCREASING ONCE AGAIN SUNDAY
AFTERNOON AND EVENING...BEFORE TAPERING OFF LATE SUNDAY NIGHT.
WITH TEMP PROFILES GENERALLY WARM THROUGH THE PERIOD WE SHOULD
MAINLY SEE RAIN AS THE PREDOMINATE PRECIP TYPE...THOUGH EARLY
SUNDAY MORNING AND LATE SUNDAY NIGHT WE COULD SEE A RAIN/SNOW
CHANGE OVER AND LIGHT SNOW ACCUMULATIONS. WITH WARM GROUND
TEMPERATURES AND THE BRIEF NATURE OF ANY CHANGE OVER...I AM NOT
SURE HOW MUCH SNOW ACCUMULATION WE WOULD ACTUALLY SEE. FOR NOW I
HAVE AROUND ONE HALF INCH OF LESS IN THE FORECAST FOR SAT
NIGHT...WITH ONLY A TRACE OF ACCUMULATION SUNDAY NIGHT.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 302 AM MDT FRI MAR 15 2013
MODELS CONTINUE TO HAVE SOLUTIONS THAT DISAGREE WITH ONE ANOTHER FOR
THE EXTENDED FORECAST. THERE ARE MANY DIFFERENCES WITH RESPECT TO
UPPER LEVEL PATTERN...SURFACE TEMPERATURES...EXTENT OF WARM AIR
ADVECTION TOWARDS THE MIDDLE OF THE WEEK AND THE EXTENT OF COLD AIR
ADVECTION BEHIND THE NEXT WEATHER SYSTEM EXPECTED TO MOVE THROUGH.
AS THE WEEKEND WEATHER SYSTEM MOVES TO THE EAST...DRY WEATHER WILL
RETURN FOR MONDAY. TEMPERATURES SHOULD BE NEAR NORMAL AS A SURFACE
HIGH SETTLES IN FROM THE NORTH ACROSS THE PLAINS. WITH NORTHWEST
FLOW...WARMING SHOULD BE LIMITED AND DRIER AIR WILL FILTER IN.
NORTHWEST WINDS COULD BE BREEZY ON MONDAY AND WITH LOW RELATIVE
HUMIDITIES...FIRE WEATHER COULD BECOME A CONCERN IF PRECIPITATION IS
NOT RECEIVED WITH THIS SYSTEM.
WEAK UPPER LEVEL RIDGING WILL SET UP ACROSS THE PLAINS FOR TUESDAY
AND WEDNESDAY. THIS WILL LEAD TO DRY WEATHER CONTINUE AND A GRADUAL
WARMING TREND. SOUTH WINDS WILL RETURN...ALLOWING MOISTURE TO RETURN
TO THE REGION AHEAD OF THE NEXT WEATHER SYSTEM.
MODEL DIFFERENCES BECOME SIGNIFICANT WITH THE NEXT LONGWAVE TROUGH
TOWARDS THE END OF THE WEEK NEXT WEEK. MODELS TEND TO AGREE THAT A
DISTURBANCE OF SOME SORT WILL CROSS THE ROCKIES AND BEGIN ITS TREK
ACROSS THE PLAINS BY THURSDAY AND INTO FRIDAY. HOWEVER...THE
STRENGTH OF THIS SYSTEM IS VERY MUCH IN QUESTION. THE GFS IS MUCH
WARMER COMPARED TO THE EUROPEAN MODEL. IF THE EUROPEAN SOLUTION PANS
OUT...THE MAJORITY OF THE PRECIPITATION WITH THIS SYSTEM WILL BE
RAIN. THE GFS COUNTERS WITH RAIN THROUGHOUT THE FORECAST. HAVE TAKEN
THE MIDDLE ROAD WITH A SLIGHT LEAN TOWARDS THE GFS SINCE THE 00Z
EUROPEAN SOLUTION IS DRASTICALLY CHANGED FROM THE 12Z RUN.
THE GFS AND EUROPEAN ARE ALSO BEGINNING TO HINT AT NORTHERLY FLOW
ALOFT WITH AN ARCTIC HIGH PRESSURE MOVING SOUTH INTO THE HIGH PLAINS
FOR THE END OF NEXT WEEK AND INTO THE WEEKEND. IF THIS WERE TO
OCCUR...BELOW NORMAL TEMPERATURES CAN BE EXPECTED...POSSIBLY ON THE
ORDER OF 10 TO 15 DEGREES. CPC OUTLOOKS TEND TO FAVOR THE COLDER
SOLUTION SO HAVE NUDGED TEMPERATURES DOWN LATER IN THE EXTEND
FORECAST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1139 AM MDT FRI MAR 15 2013
VFR CONDITIONS FORECAST FOR THE 18Z TAFS. VISIBLE SATELLITE IS
SHOWING SOME CLEARING OVER WESTERN NEBRASKA WHICH IS ALLOWING
GUSTS UP TO 25 KTS TO DEVELOP. FORESEE THIS ALSO HAPPENING TO KMCK
THIS AFTERNOON AND POSSIBLY KGLD..ALTHOUGH THE CLOUDS MAY NOT
CLEAR FOR KGLD WHICH WILL HINDER THE GUSTS FROM DEVELOPING. THE
GUSTS WILL CEASE EARLY THIS EVENING AS TEMPERATURES COOL.
OVERNIGHT WINDS WILL BECOME LIGHT AND CHANGE TO THE NORTH AS A
COLD FRONT MOVES IN FROM THE NORTH. THE NORTHERLY WINDS WILL
CONTINUE UNTIL MID TO LATE SATURDAY MORNING WHEN THEY WILL TURN TO
MORE OF AN EASTERLY DIRECTION. PRECIPITATION CHANCES WILL INCREASE
FROM WEST TO EAST...BUT SHOULD REMAIN MAINLY WEST OF KGLD UNTIL
EARLY AFTERNOON.
&&
.FIRE WEATHER...
ISSUED AT 221 AM MDT FRI MAR 15 2013
RECORD HIGH TEMPERATURES AND LOW TD VALUES IN THE TEENS WILL LEAD TO
LOW RH VALUES THIS AFTERNOON ACROSS THE CWA. WE SHOULD SEE RH VALUES
AROUND 10 PERCENT IN THE SOUTHWEST TO AROUND 15 PERCENT ACROSS OUR
NEBRASKA COUNTIES. GUIDANCE CONTINUES TO SHOW SOME INCREASE IN WINDS
ALOFT WITH UNIDIRECTIONAL FLOW...HOWEVER I AM NOT SURE WE ARE GOING
TO SEE THE THREE HOURS NECESSARY OF GUSTS AROUND 25MPH FOR A RED
FLAG WARNING IN THE NORTH...AND WINDS SHOULD BE LIGHTER IN THE SOUTH.
INCREASING CLOUDS FROM THE NORTHWEST COULD ALSO LEAD TO LESS MIXING
AND LIGHTER GUSTS. WITH TOO MUCH UNCERTAINTY REGARDING WINDS...I
DECIDED AGAINST ISSUING A RED FLAG WARNING...AND WILL ALLOW DAY
SHIFT TO MONITOR TRENDS.
&&
.CLIMATE...
ISSUED AT 810 PM MDT THU MAR 14 2013
THE FOLLOWING IS A LIST OF RECORD HIGH TEMPERATURES FOR FRIDAY
MARCH 15.
GOODLAND......82 IN 1935
HILL CITY.....84 IN 2003
MCCOOK........89 IN 1935
BURLINGTON....77 IN 1935
YUMA..........81
TRIBUNE.......84
COLBY.........86
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JTL
SHORT TERM...DR
LONG TERM...RRH
AVIATION...JTL
FIRE WEATHER...DR
CLIMATE...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1147 AM MDT FRI MAR 15 2013
.UPDATE...
ISSUED AT 834 AM MDT FRI MAR 15 2013
STILL SOME UNCERTAINTY REGARDING CRITICAL FIRE WEATHER CONDITIONS
THIS AFTERNOON. MODELS CONTINUE TO SHOW THE POSSIBILITY OF GUSTS
OF 30 MPH DEVELOPING NORTHEAST OF A LINE FROM HILL CITY TO
STRATTON NEBRASKA. HOWEVER THERE MAY BE SOME MID/HIGH CLOUDS OVER
THAT AREA THIS AFTERNOON WHICH WOULD KEEP THE WIND GUSTS LOWER.
TIMING IN THE BACK EDGE OF THE CLOUD BAND CURRENTLY OVER SOUTHEAST
WYOMING WOULD PLACE IT OVER THOSE LOCATIONS DURING PEAK HEATING
THIS AFTERNOON. IF THIS DOES OCCUR THERE WOULD STILL BE ONLY 3
HOURS AT BEST FOR GUSTS TO MEET CRITERIA...ASSUMING NO CLOUDS
DEVELOP OVER THE AREA LIKE MODELS ARE HINTING AT. WITH THESE
CONSIDERATIONS IN MIND AM STILL GOING TO HOLD OFF ISSUING A FIRE
WEATHER HIGHLIGHT DUE TO UNCERTAINTIES THAT THE WIND GUSTS WILL
LAST THE REQUIRED THREE HOURS.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 233 AM MDT FRI MAR 15 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW NW FLOW IN PLACE ACROSS
THE INTERMOUNTAIN WEST AND CENTRAL PLAINS WITH A RIDGE CENTERED
OVER SOUTHERN ARIZONA. AT THE SURFACE SEVERAL WEAK SURFACE TROUGHS
ARE IN PLACE OVER NW KANSAS AND EASTERN COLORADO.
H5 RIDGE IS EXPECTED TO CONTINUE TO WEAKEN WITH NW FLOW BECOMING
WESTERLY THIS AFTERNOON. WITH DEEP WESTERLY/DOWNSLOPE FLOW IN PLACE
ACROSS THE PLAINS WE WILL CONTINUE TO SEE WAA THROUGH THIS
AFTERNOON. CURRENTLY EXPECT NEAR RECORD HIGHS IN THE 80S ACROSS
MUCH OF THE CWA WITH SEVERAL LOCATIONS EXPECTED TO AT LEAST TIE
DAILY RECORDS.
A BACK DOOR COLD FRONT WILL DROP SOUTH OVER THE NORTHERN PLAINS AND
THROUGH THE CWA SATURDAY. SEASONAL TEMPERATURES WILL RETURN TO THIS
WEEKEND WITH HIGHS IN THE UPPER 40S TO MID 50S (COOLEST NORTHEAST-
WARMEST SOUTHWEST) AND OVERNIGHT LOWS NEAR FREEZING.
GUIDANCE CONTINUES TO SHOW SOME LIGHT QPF IN PLACE LATE TONIGHT
AFTER 06Z IN THE NORTHWEST SPREADING SOUTHEAST. HOWEVER...MODEL
SOUNDINGS CONTINUE TO SHOW A DRY LAYER BELOW 600MB THROUGH
SATURDAY MORNING...SO IM SKEPTICAL WHETHER WE WILL SEE MEASURABLE
TONIGHT. I LEFT 20 POPS IN PLACE TO ACCOUNT FOR POTENTIAL. BETTER
CHANCES SHOULD BE LATER IN THE DAY SATURDAY THROUGH SATURDAY NIGHT
AS LARGE SCALE FORCING AND WEAK INSTABILITY OVERSPREAD THE
REGION...WHEN A SHORTWAVE TROUGH MOVES ACROSS THE CENTRAL ROCKIES.
I INCREASE POPS TO LIKELY CATEGORY AROUND 00Z SAT THROUGH SAT
EVENING...WITH A DECREASING IN COVERAGE AFTER 06Z. A SECOND
STRONGER SHORTWAVE TROUGH WILL PASS THROUGH THE REGION
SUNDAY...WITH PRECIP CHANCES INCREASING ONCE AGAIN SUNDAY
AFTERNOON AND EVENING...BEFORE TAPERING OFF LATE SUNDAY NIGHT.
WITH TEMP PROFILES GENERALLY WARM THROUGH THE PERIOD WE SHOULD
MAINLY SEE RAIN AS THE PREDOMINATE PRECIP TYPE...THOUGH EARLY
SUNDAY MORNING AND LATE SUNDAY NIGHT WE COULD SEE A RAIN/SNOW
CHANGE OVER AND LIGHT SNOW ACCUMULATIONS. WITH WARM GROUND
TEMPERATURES AND THE BRIEF NATURE OF ANY CHANGE OVER...I AM NOT
SURE HOW MUCH SNOW ACCUMULATION WE WOULD ACTUALLY SEE. FOR NOW I
HAVE AROUND ONE HALF INCH OF LESS IN THE FORECAST FOR SAT
NIGHT...WITH ONLY A TRACE OF ACCUMULATION SUNDAY NIGHT.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 302 AM MDT FRI MAR 15 2013
MODELS CONTINUE TO HAVE SOLUTIONS THAT DISAGREE WITH ONE ANOTHER FOR
THE EXTENDED FORECAST. THERE ARE MANY DIFFERENCES WITH RESPECT TO
UPPER LEVEL PATTERN...SURFACE TEMPERATURES...EXTENT OF WARM AIR
ADVECTION TOWARDS THE MIDDLE OF THE WEEK AND THE EXTENT OF COLD AIR
ADVECTION BEHIND THE NEXT WEATHER SYSTEM EXPECTED TO MOVE THROUGH.
AS THE WEEKEND WEATHER SYSTEM MOVES TO THE EAST...DRY WEATHER WILL
RETURN FOR MONDAY. TEMPERATURES SHOULD BE NEAR NORMAL AS A SURFACE
HIGH SETTLES IN FROM THE NORTH ACROSS THE PLAINS. WITH NORTHWEST
FLOW...WARMING SHOULD BE LIMITED AND DRIER AIR WILL FILTER IN.
NORTHWEST WINDS COULD BE BREEZY ON MONDAY AND WITH LOW RELATIVE
HUMIDITIES...FIRE WEATHER COULD BECOME A CONCERN IF PRECIPITATION IS
NOT RECEIVED WITH THIS SYSTEM.
WEAK UPPER LEVEL RIDGING WILL SET UP ACROSS THE PLAINS FOR TUESDAY
AND WEDNESDAY. THIS WILL LEAD TO DRY WEATHER CONTINUE AND A GRADUAL
WARMING TREND. SOUTH WINDS WILL RETURN...ALLOWING MOISTURE TO RETURN
TO THE REGION AHEAD OF THE NEXT WEATHER SYSTEM.
MODEL DIFFERENCES BECOME SIGNIFICANT WITH THE NEXT LONGWAVE TROUGH
TOWARDS THE END OF THE WEEK NEXT WEEK. MODELS TEND TO AGREE THAT A
DISTURBANCE OF SOME SORT WILL CROSS THE ROCKIES AND BEGIN ITS TREK
ACROSS THE PLAINS BY THURSDAY AND INTO FRIDAY. HOWEVER...THE
STRENGTH OF THIS SYSTEM IS VERY MUCH IN QUESTION. THE GFS IS MUCH
WARMER COMPARED TO THE EUROPEAN MODEL. IF THE EUROPEAN SOLUTION PANS
OUT...THE MAJORITY OF THE PRECIPITATION WITH THIS SYSTEM WILL BE
RAIN. THE GFS COUNTERS WITH RAIN THROUGHOUT THE FORECAST. HAVE TAKEN
THE MIDDLE ROAD WITH A SLIGHT LEAN TOWARDS THE GFS SINCE THE 00Z
EUROPEAN SOLUTION IS DRASTICALLY CHANGED FROM THE 12Z RUN.
THE GFS AND EUROPEAN ARE ALSO BEGINNING TO HINT AT NORTHERLY FLOW
ALOFT WITH AN ARCTIC HIGH PRESSURE MOVING SOUTH INTO THE HIGH PLAINS
FOR THE END OF NEXT WEEK AND INTO THE WEEKEND. IF THIS WERE TO
OCCUR...BELOW NORMAL TEMPERATURES CAN BE EXPECTED...POSSIBLY ON THE
ORDER OF 10 TO 15 DEGREES. CPC OUTLOOKS TEND TO FAVOR THE COLDER
SOLUTION SO HAVE NUDGED TEMPERATURES DOWN LATER IN THE EXTEND
FORECAST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1139 AM MDT FRI MAR 15 2013
VFR CONDITIONS FORECAST FOR THE 18Z TAFS. VISIBLE SATELLITE IS
SHOWING SOME CLEARING OVER WESTERN NEBRASKA WHICH IS ALLOWING
GUSTS UP TO 25 KTS TO DEVELOP. FORESEE THIS ALSO HAPPENING TO KMCK
THIS AFTERNOON AND POSSIBLY KGLD..ALTHOUGH THE CLOUDS MAY NOT
CLEAR FOR KGLD WHICH WILL HINDER THE GUSTS FROM DEVELOPING. THE
GUSTS WILL CEASE EARLY THIS EVENING AS TEMPERATURES COOL.
OVERNIGHT WINDS WILL BECOME LIGHT AND CHANGE TO THE NORTH AS A
COLD FRONT MOVES IN FROM THE NORTH. THE NORTHERLY WINDS WILL
CONTINUE UNTIL MID TO LATE SATURDAY MORNING WHEN THEY WILL TURN TO
MORE OF AN EASTERLY DIRECTION. PRECIPITATION CHANCES WILL INCREASE
FROM WEST TO EAST...BUT SHOULD REMAIN MAINLY WEST OF KGLD UNTIL
EARLY AFTERNOON.
&&
.FIRE WEATHER...
ISSUED AT 221 AM MDT FRI MAR 15 2013
RECORD HIGH TEMPERATURES AND LOW TD VALUES IN THE TEENS WILL LEAD TO
LOW RH VALUES THIS AFTERNOON ACROSS THE CWA. WE SHOULD SEE RH VALUES
AROUND 10 PERCENT IN THE SOUTHWEST TO AROUND 15 PERCENT ACROSS OUR
NEBRASKA COUNTIES. GUIDANCE CONTINUES TO SHOW SOME INCREASE IN WINDS
ALOFT WITH UNIDIRECTIONAL FLOW...HOWEVER I AM NOT SURE WE ARE GOING
TO SEE THE THREE HOURS NECESSARY OF GUSTS AROUND 25MPH FOR A RED
FLAG WARNING IN THE NORTH...AND WINDS SHOULD BE LIGHTER IN THE SOUTH.
INCREASING CLOUDS FROM THE NORTHWEST COULD ALSO LEAD TO LESS MIXING
AND LIGHTER GUSTS. WITH TOO MUCH UNCERTAINTY REGARDING WINDS...I
DECIDED AGAINST ISSUING A RED FLAG WARNING...AND WILL ALLOW DAY
SHIFT TO MONITOR TRENDS.
&&
.CLIMATE...
ISSUED AT 810 PM MDT THU MAR 14 2013
THE FOLLOWING IS A LIST OF RECORD HIGH TEMPERATURES FOR FRIDAY
MARCH 15.
GOODLAND......82 IN 1935
HILL CITY.....84 IN 2003
MCCOOK........89 IN 1935
BURLINGTON....77 IN 1935
YUMA..........81
TRIBUNE.......84
COLBY.........86
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JTL
SHORT TERM...DR
LONG TERM...RRH
AVIATION...JTL
FIRE WEATHER...DR
CLIMATE...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
842 AM MDT FRI MAR 15 2013
.UPDATE...
ISSUED AT 834 AM MDT FRI MAR 15 2013
STILL SOME UNCERTAINTY REGARDING CRITICAL FIRE WEATHER CONDITIONS
THIS AFTERNOON. MODELS CONTINUE TO SHOW THE POSSIBILITY OF GUSTS
OF 30 MPH DEVELOPING NORTHEAST OF A LINE FROM HILL CITY TO
STRATTON NEBRASKA. HOWEVER THERE MAY BE SOME MID/HIGH CLOUDS OVER
THAT AREA THIS AFTERNOON WHICH WOULD KEEP THE WIND GUSTS LOWER.
TIMING IN THE BACK EDGE OF THE CLOUD BAND CURRENTLY OVER SOUTHEAST
WYOMING WOULD PLACE IT OVER THOSE LOCATIONS DURING PEAK HEATING
THIS AFTERNOON. IF THIS DOES OCCUR THERE WOULD STILL BE ONLY 3
HOURS AT BEST FOR GUSTS TO MEET CRITERIA...ASSUMING NO CLOUDS
DEVELOP OVER THE AREA LIKE MODELS ARE HINTING AT. WITH THESE
CONSIDERATIONS IN MIND AM STILL GOING TO HOLD OFF ISSUING A FIRE
WEATHER HIGHLIGHT DUE TO UNCERTAINTIES THAT THE WIND GUSTS WILL
LAST THE REQUIRED THREE HOURS.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 233 AM MDT FRI MAR 15 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW NW FLOW IN PLACE ACROSS
THE INTERMOUNTAIN WEST AND CENTRAL PLAINS WITH A RIDGE CENTERED
OVER SOUTHERN ARIZONA. AT THE SURFACE SEVERAL WEAK SURFACE TROUGHS
ARE IN PLACE OVER NW KANSAS AND EASTERN COLORADO.
H5 RIDGE IS EXPECTED TO CONTINUE TO WEAKEN WITH NW FLOW BECOMING
WESTERLY THIS AFTERNOON. WITH DEEP WESTERLY/DOWNSLOPE FLOW IN PLACE
ACROSS THE PLAINS WE WILL CONTINUE TO SEE WAA THROUGH THIS
AFTERNOON. CURRENTLY EXPECT NEAR RECORD HIGHS IN THE 80S ACROSS
MUCH OF THE CWA WITH SEVERAL LOCATIONS EXPECTED TO AT LEAST TIE
DAILY RECORDS.
A BACK DOOR COLD FRONT WILL DROP SOUTH OVER THE NORTHERN PLAINS AND
THROUGH THE CWA SATURDAY. SEASONAL TEMPERATURES WILL RETURN TO THIS
WEEKEND WITH HIGHS IN THE UPPER 40S TO MID 50S (COOLEST NORTHEAST-
WARMEST SOUTHWEST) AND OVERNIGHT LOWS NEAR FREEZING.
GUIDANCE CONTINUES TO SHOW SOME LIGHT QPF IN PLACE LATE TONIGHT
AFTER 06Z IN THE NORTHWEST SPREADING SOUTHEAST. HOWEVER...MODEL
SOUNDINGS CONTINUE TO SHOW A DRY LAYER BELOW 600MB THROUGH
SATURDAY MORNING...SO IM SKEPTICAL WHETHER WE WILL SEE MEASURABLE
TONIGHT. I LEFT 20 POPS IN PLACE TO ACCOUNT FOR POTENTIAL. BETTER
CHANCES SHOULD BE LATER IN THE DAY SATURDAY THROUGH SATURDAY NIGHT
AS LARGE SCALE FORCING AND WEAK INSTABILITY OVERSPREAD THE
REGION...WHEN A SHORTWAVE TROUGH MOVES ACROSS THE CENTRAL ROCKIES.
I INCREASE POPS TO LIKELY CATEGORY AROUND 00Z SAT THROUGH SAT
EVENING...WITH A DECREASING IN COVERAGE AFTER 06Z. A SECOND
STRONGER SHORTWAVE TROUGH WILL PASS THROUGH THE REGION
SUNDAY...WITH PRECIP CHANCES INCREASING ONCE AGAIN SUNDAY
AFTERNOON AND EVENING...BEFORE TAPERING OFF LATE SUNDAY NIGHT.
WITH TEMP PROFILES GENERALLY WARM THROUGH THE PERIOD WE SHOULD
MAINLY SEE RAIN AS THE PREDOMINATE PRECIP TYPE...THOUGH EARLY
SUNDAY MORNING AND LATE SUNDAY NIGHT WE COULD SEE A RAIN/SNOW
CHANGE OVER AND LIGHT SNOW ACCUMULATIONS. WITH WARM GROUND
TEMPERATURES AND THE BRIEF NATURE OF ANY CHANGE OVER...I AM NOT
SURE HOW MUCH SNOW ACCUMULATION WE WOULD ACTUALLY SEE. FOR NOW I
HAVE AROUND ONE HALF INCH OF LESS IN THE FORECAST FOR SAT
NIGHT...WITH ONLY A TRACE OF ACCUMULATION SUNDAY NIGHT.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 302 AM MDT FRI MAR 15 2013
MODELS CONTINUE TO HAVE SOLUTIONS THAT DISAGREE WITH ONE ANOTHER FOR
THE EXTENDED FORECAST. THERE ARE MANY DIFFERENCES WITH RESPECT TO
UPPER LEVEL PATTERN...SURFACE TEMPERATURES...EXTENT OF WARM AIR
ADVECTION TOWARDS THE MIDDLE OF THE WEEK AND THE EXTENT OF COLD AIR
ADVECTION BEHIND THE NEXT WEATHER SYSTEM EXPECTED TO MOVE THROUGH.
AS THE WEEKEND WEATHER SYSTEM MOVES TO THE EAST...DRY WEATHER WILL
RETURN FOR MONDAY. TEMPERATURES SHOULD BE NEAR NORMAL AS A SURFACE
HIGH SETTLES IN FROM THE NORTH ACROSS THE PLAINS. WITH NORTHWEST
FLOW...WARMING SHOULD BE LIMITED AND DRIER AIR WILL FILTER IN.
NORTHWEST WINDS COULD BE BREEZY ON MONDAY AND WITH LOW RELATIVE
HUMIDITIES...FIRE WEATHER COULD BECOME A CONCERN IF PRECIPITATION IS
NOT RECEIVED WITH THIS SYSTEM.
WEAK UPPER LEVEL RIDGING WILL SET UP ACROSS THE PLAINS FOR TUESDAY
AND WEDNESDAY. THIS WILL LEAD TO DRY WEATHER CONTINUE AND A GRADUAL
WARMING TREND. SOUTH WINDS WILL RETURN...ALLOWING MOISTURE TO RETURN
TO THE REGION AHEAD OF THE NEXT WEATHER SYSTEM.
MODEL DIFFERENCES BECOME SIGNIFICANT WITH THE NEXT LONGWAVE TROUGH
TOWARDS THE END OF THE WEEK NEXT WEEK. MODELS TEND TO AGREE THAT A
DISTURBANCE OF SOME SORT WILL CROSS THE ROCKIES AND BEGIN ITS TREK
ACROSS THE PLAINS BY THURSDAY AND INTO FRIDAY. HOWEVER...THE
STRENGTH OF THIS SYSTEM IS VERY MUCH IN QUESTION. THE GFS IS MUCH
WARMER COMPARED TO THE EUROPEAN MODEL. IF THE EUROPEAN SOLUTION PANS
OUT...THE MAJORITY OF THE PRECIPITATION WITH THIS SYSTEM WILL BE
RAIN. THE GFS COUNTERS WITH RAIN THROUGHOUT THE FORECAST. HAVE TAKEN
THE MIDDLE ROAD WITH A SLIGHT LEAN TOWARDS THE GFS SINCE THE 00Z
EUROPEAN SOLUTION IS DRASTICALLY CHANGED FROM THE 12Z RUN.
THE GFS AND EUROPEAN ARE ALSO BEGINNING TO HINT AT NORTHERLY FLOW
ALOFT WITH AN ARCTIC HIGH PRESSURE MOVING SOUTH INTO THE HIGH PLAINS
FOR THE END OF NEXT WEEK AND INTO THE WEEKEND. IF THIS WERE TO
OCCUR...BELOW NORMAL TEMPERATURES CAN BE EXPECTED...POSSIBLY ON THE
ORDER OF 10 TO 15 DEGREES. CPC OUTLOOKS TEND TO FAVOR THE COLDER
SOLUTION SO HAVE NUDGED TEMPERATURES DOWN LATER IN THE EXTEND
FORECAST.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 541 AM MDT FRI MAR 15 2013
VFR CONDITIONS EXPECTED TO PREVAIL AT BOTH KGLD AND KMCK
TERMINALS. SOUTHWEST WINDS WILL BACK TO THE WEST/NORTHWEST BY THIS
AFTERNOON AND INCREASE WITH GUSTS AROUND AROUND 21KT. GUSTS ARE
MOST LIKELY AT KMCK AND MIGHT NOT PREVAIL AT KGLD SO HAVE KEPT
TEMPO GROUP FOR KGLD. WINDS SHOULD DECREASE AROUND SUNSET WITH END
OF DIURNAL HEATING AND THEN BACK TO THE NORTHEAST AROUND 02-03Z
WITH FRONTAL PASSAGE.
&&
.FIRE WEATHER...
ISSUED AT 221 AM MDT FRI MAR 15 2013
RECORD HIGH TEMPERATURES AND LOW TD VALUES IN THE TEENS WILL LEAD TO
LOW RH VALUES THIS AFTERNOON ACROSS THE CWA. WE SHOULD SEE RH VALUES
AROUND 10 PERCENT IN THE SOUTHWEST TO AROUND 15 PERCENT ACROSS OUR
NEBRASKA COUNTIES. GUIDANCE CONTINUES TO SHOW SOME INCREASE IN WINDS
ALOFT WITH UNIDIRECTIONAL FLOW...HOWEVER I AM NOT SURE WE ARE GOING
TO SEE THE THREE HOURS NECESSARY OF GUSTS AROUND 25MPH FOR A RED
FLAG WARNING IN THE NORTH...AND WINDS SHOULD BE LIGHTER IN THE SOUTH.
INCREASING CLOUDS FROM THE NORTHWEST COULD ALSO LEAD TO LESS MIXING
AND LIGHTER GUSTS. WITH TOO MUCH UNCERTAINTY REGARDING WINDS...I
DECIDED AGAINST ISSUING A RED FLAG WARNING...AND WILL ALLOW DAY
SHIFT TO MONITOR TRENDS.
&&
.CLIMATE...
ISSUED AT 810 PM MDT THU MAR 14 2013
THE FOLLOWING IS A LIST OF RECORD HIGH TEMPERATURES FOR FRIDAY
MARCH 15.
GOODLAND......82 IN 1935
HILL CITY.....84 IN 2003
MCCOOK........89 IN 1935
BURLINGTON....77 IN 1935
YUMA..........81
TRIBUNE.......84
COLBY.........86
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JTL
SHORT TERM...DR
LONG TERM...RRH
AVIATION...DR
FIRE WEATHER...DR
CLIMATE...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
541 AM MDT FRI MAR 15 2013
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 233 AM MDT FRI MAR 15 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW NW FLOW IN PLACE ACROSS
THE INTERMOUNTAIN WEST AND CENTRAL PLAINS WITH A RIDGE CENTERED
OVER SOUTHERN ARIZONA. AT THE SURFACE SEVERAL WEAK SURFACE TROUGHS
ARE IN PLACE OVER NW KANSAS AND EASTERN COLORADO.
H5 RIDGE IS EXPECTED TO CONTINUE TO WEAKEN WITH NW FLOW BECOMING
WESTERLY THIS AFTERNOON. WITH DEEP WESTERLY/DOWNSLOPE FLOW IN PLACE
ACROSS THE PLAINS WE WILL CONTINUE TO SEE WAA THROUGH THIS
AFTERNOON. CURRENTLY EXPECT NEAR RECORD HIGHS IN THE 80S ACROSS
MUCH OF THE CWA WITH SEVERAL LOCATIONS EXPECTED TO AT LEAST TIE
DAILY RECORDS.
A BACK DOOR COLD FRONT WILL DROP SOUTH OVER THE NORTHERN PLAINS AND
THROUGH THE CWA SATURDAY. SEASONAL TEMPERATURES WILL RETURN TO THIS
WEEKEND WITH HIGHS IN THE UPPER 40S TO MID 50S (COOLEST NORTHEAST-
WARMEST SOUTHWEST) AND OVERNIGHT LOWS NEAR FREEZING.
GUIDANCE CONTINUES TO SHOW SOME LIGHT QPF IN PLACE LATE TONIGHT
AFTER 06Z IN THE NORTHWEST SPREADING SOUTHEAST. HOWEVER...MODEL
SOUNDINGS CONTINUE TO SHOW A DRY LAYER BELOW 600MB THROUGH
SATURDAY MORNING...SO IM SKEPTICAL WHETHER WE WILL SEE MEASURABLE
TONIGHT. I LEFT 20 POPS IN PLACE TO ACCOUNT FOR POTENTIAL. BETTER
CHANCES SHOULD BE LATER IN THE DAY SATURDAY THROUGH SATURDAY NIGHT
AS LARGE SCALE FORCING AND WEAK INSTABILITY OVERSPREAD THE
REGION...WHEN A SHORTWAVE TROUGH MOVES ACROSS THE CENTRAL ROCKIES.
I INCREASE POPS TO LIKELY CATEGORY AROUND 00Z SAT THROUGH SAT
EVENING...WITH A DECREASING IN COVERAGE AFTER 06Z. A SECOND
STRONGER SHORTWAVE TROUGH WILL PASS THROUGH THE REGION
SUNDAY...WITH PRECIP CHANCES INCREASING ONCE AGAIN SUNDAY
AFTERNOON AND EVENING...BEFORE TAPERING OFF LATE SUNDAY NIGHT.
WITH TEMP PROFILES GENERALLY WARM THROUGH THE PERIOD WE SHOULD
MAINLY SEE RAIN AS THE PREDOMINATE PRECIP TYPE...THOUGH EARLY
SUNDAY MORNING AND LATE SUNDAY NIGHT WE COULD SEE A RAIN/SNOW
CHANGE OVER AND LIGHT SNOW ACCUMULATIONS. WITH WARM GROUND
TEMPERATURES AND THE BRIEF NATURE OF ANY CHANGE OVER...I AM NOT
SURE HOW MUCH SNOW ACCUMULATION WE WOULD ACTUALLY SEE. FOR NOW I
HAVE AROUND ONE HALF INCH OF LESS IN THE FORECAST FOR SAT
NIGHT...WITH ONLY A TRACE OF ACCUMULATION SUNDAY NIGHT.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 302 AM MDT FRI MAR 15 2013
MODELS CONTINUE TO HAVE SOLUTIONS THAT DISAGREE WITH ONE ANOTHER FOR
THE EXTENDED FORECAST. THERE ARE MANY DIFFERENCES WITH RESPECT TO
UPPER LEVEL PATTERN...SURFACE TEMPERATURES...EXTENT OF WARM AIR
ADVECTION TOWARDS THE MIDDLE OF THE WEEK AND THE EXTENT OF COLD AIR
ADVECTION BEHIND THE NEXT WEATHER SYSTEM EXPECTED TO MOVE THROUGH.
AS THE WEEKEND WEATHER SYSTEM MOVES TO THE EAST...DRY WEATHER WILL
RETURN FOR MONDAY. TEMPERATURES SHOULD BE NEAR NORMAL AS A SURFACE
HIGH SETTLES IN FROM THE NORTH ACROSS THE PLAINS. WITH NORTHWEST
FLOW...WARMING SHOULD BE LIMITED AND DRIER AIR WILL FILTER IN.
NORTHWEST WINDS COULD BE BREEZY ON MONDAY AND WITH LOW RELATIVE
HUMIDITIES...FIRE WEATHER COULD BECOME A CONCERN IF PRECIPITATION IS
NOT RECEIVED WITH THIS SYSTEM.
WEAK UPPER LEVEL RIDGING WILL SET UP ACROSS THE PLAINS FOR TUESDAY
AND WEDNESDAY. THIS WILL LEAD TO DRY WEATHER CONTINUE AND A GRADUAL
WARMING TREND. SOUTH WINDS WILL RETURN...ALLOWING MOISTURE TO RETURN
TO THE REGION AHEAD OF THE NEXT WEATHER SYSTEM.
MODEL DIFFERENCES BECOME SIGNIFICANT WITH THE NEXT LONGWAVE TROUGH
TOWARDS THE END OF THE WEEK NEXT WEEK. MODELS TEND TO AGREE THAT A
DISTURBANCE OF SOME SORT WILL CROSS THE ROCKIES AND BEGIN ITS TREK
ACROSS THE PLAINS BY THURSDAY AND INTO FRIDAY. HOWEVER...THE
STRENGTH OF THIS SYSTEM IS VERY MUCH IN QUESTION. THE GFS IS MUCH
WARMER COMPARED TO THE EUROPEAN MODEL. IF THE EUROPEAN SOLUTION PANS
OUT...THE MAJORITY OF THE PRECIPITATION WITH THIS SYSTEM WILL BE
RAIN. THE GFS COUNTERS WITH RAIN THROUGHOUT THE FORECAST. HAVE TAKEN
THE MIDDLE ROAD WITH A SLIGHT LEAN TOWARDS THE GFS SINCE THE 00Z
EUROPEAN SOLUTION IS DRASTICALLY CHANGED FROM THE 12Z RUN.
THE GFS AND EUROPEAN ARE ALSO BEGINNING TO HINT AT NORTHERLY FLOW
ALOFT WITH AN ARCTIC HIGH PRESSURE MOVING SOUTH INTO THE HIGH PLAINS
FOR THE END OF NEXT WEEK AND INTO THE WEEKEND. IF THIS WERE TO
OCCUR...BELOW NORMAL TEMPERATURES CAN BE EXPECTED...POSSIBLY ON THE
ORDER OF 10 TO 15 DEGREES. CPC OUTLOOKS TEND TO FAVOR THE COLDER
SOLUTION SO HAVE NUDGED TEMPERATURES DOWN LATER IN THE EXTEND
FORECAST.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 541 AM MDT FRI MAR 15 2013
VFR CONDITIONS EXPECTED TO PREVAIL AT BOTH KGLD AND KMCK
TERMINALS. SOUTHWEST WINDS WILL BACK TO THE WEST/NORTHWEST BY THIS
AFTERNOON AND INCREASE WITH GUSTS AROUND AROUND 21KT. GUSTS ARE
MOST LIKELY AT KMCK AND MIGHT NOT PREVAIL AT KGLD SO HAVE KEPT
TEMPO GROUP FOR KGLD. WINDS SHOULD DECREASE AROUND SUNSET WITH END
OF DIURNAL HEATING AND THEN BACK TO THE NORTHEAST AROUND 02-03Z
WITH FRONTAL PASSAGE.
&&
.FIRE WEATHER...
ISSUED AT 221 AM MDT FRI MAR 15 2013
RECORD HIGH TEMPERATURES AND LOW TD VALUES IN THE TEENS WILL LEAD TO
LOW RH VALUES THIS AFTERNOON ACROSS THE CWA. WE SHOULD SEE RH VALUES
AROUND 10 PERCENT IN THE SOUTHWEST TO AROUND 15 PERCENT ACROSS OUR
NEBRASKA COUNTIES. GUIDANCE CONTINUES TO SHOW SOME INCREASE IN WINDS
ALOFT WITH UNIDIRECTIONAL FLOW...HOWEVER I AM NOT SURE WE ARE GOING
TO SEE THE THREE HOURS NECESSARY OF GUSTS AROUND 25MPH FOR A RED
FLAG WARNING IN THE NORTH...AND WINDS SHOULD BE LIGHTER IN THE SOUTH.
INCREASING CLOUDS FROM THE NORTHWEST COULD ALSO LEAD TO LESS MIXING
AND LIGHTER GUSTS. WITH TOO MUCH UNCERTAINTY REGARDING WINDS...I
DECIDED AGAINST ISSUING A RED FLAG WARNING...AND WILL ALLOW DAY
SHIFT TO MONITOR TRENDS.
&&
.CLIMATE...
ISSUED AT 810 PM MDT THU MAR 14 2013
THE FOLLOWING IS A LIST OF RECORD HIGH TEMPERATURES FOR FRIDAY
MARCH 15.
GOODLAND......82 IN 1935
HILL CITY.....84 IN 2003
MCCOOK........89 IN 1935
BURLINGTON....77 IN 1935
YUMA..........81
TRIBUNE.......84
COLBY.........86
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...RRH
AVIATION...DR
FIRE WEATHER...DR
CLIMATE...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
302 AM MDT FRI MAR 15 2013
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 233 AM MDT FRI MAR 15 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW NW FLOW IN PLACE ACROSS
THE INTERMOUNTAIN WEST AND CENTRAL PLAINS WITH A RIDGE CENTERED
OVER SOUTHERN ARIZONA. AT THE SURFACE SEVERAL WEAK SURFACE TROUGHS
ARE IN PLACE OVER NW KANSAS AND EASTERN COLORADO.
H5 RIDGE IS EXPECTED TO CONTINUE TO WEAKEN WITH NW FLOW BECOMING
WESTERLY THIS AFTERNOON. WITH DEEP WESTERLY/DOWNSLOPE FLOW IN PLACE
ACROSS THE PLAINS WE WILL CONTINUE TO SEE WAA THROUGH THIS
AFTERNOON. CURRENTLY EXPECT NEAR RECORD HIGHS IN THE 80S ACROSS
MUCH OF THE CWA WITH SEVERAL LOCATIONS EXPECTED TO AT LEAST TIE
DAILY RECORDS.
A BACK DOOR COLD FRONT WILL DROP SOUTH OVER THE NORTHERN PLAINS AND
THROUGH THE CWA SATURDAY. SEASONAL TEMPERATURES WILL RETURN TO THIS
WEEKEND WITH HIGHS IN THE UPPER 40S TO MID 50S (COOLEST NORTHEAST-
WARMEST SOUTHWEST) AND OVERNIGHT LOWS NEAR FREEZING.
GUIDANCE CONTINUES TO SHOW SOME LIGHT QPF IN PLACE LATE TONIGHT
AFTER 06Z IN THE NORTHWEST SPREADING SOUTHEAST. HOWEVER...MODEL
SOUNDINGS CONTINUE TO SHOW A DRY LAYER BELOW 600MB THROUGH
SATURDAY MORNING...SO IM SKEPTICAL WHETHER WE WILL SEE MEASURABLE
TONIGHT. I LEFT 20 POPS IN PLACE TO ACCOUNT FOR POTENTIAL. BETTER
CHANCES SHOULD BE LATER IN THE DAY SATURDAY THROUGH SATURDAY NIGHT
AS LARGE SCALE FORCING AND WEAK INSTABILITY OVERSPREAD THE
REGION...WHEN A SHORTWAVE TROUGH MOVES ACROSS THE CENTRAL ROCKIES.
I INCREASE POPS TO LIKELY CATEGORY AROUND 00Z SAT THROUGH SAT
EVENING...WITH A DECREASING IN COVERAGE AFTER 06Z. A SECOND
STRONGER SHORTWAVE TROUGH WILL PASS THROUGH THE REGION
SUNDAY...WITH PRECIP CHANCES INCREASING ONCE AGAIN SUNDAY
AFTERNOON AND EVENING...BEFORE TAPERING OFF LATE SUNDAY NIGHT.
WITH TEMP PROFILES GENERALLY WARM THROUGH THE PERIOD WE SHOULD
MAINLY SEE RAIN AS THE PREDOMINATE PRECIP TYPE...THOUGH EARLY
SUNDAY MORNING AND LATE SUNDAY NIGHT WE COULD SEE A RAIN/SNOW
CHANGE OVER AND LIGHT SNOW ACCUMULATIONS. WITH WARM GROUND
TEMPERATURES AND THE BRIEF NATURE OF ANY CHANGE OVER...I AM NOT
SURE HOW MUCH SNOW ACCUMULATION WE WOULD ACTUALLY SEE. FOR NOW I
HAVE AROUND ONE HALF INCH OF LESS IN THE FORECAST FOR SAT
NIGHT...WITH ONLY A TRACE OF ACCUMULATION SUNDAY NIGHT.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 302 AM MDT FRI MAR 15 2013
MODELS CONTINUE TO HAVE SOLUTIONS THAT DISAGREE WITH ONE ANOTHER FOR
THE EXTENDED FORECAST. THERE ARE MANY DIFFERENCES WITH RESPECT TO
UPPER LEVEL PATTERN...SURFACE TEMPERATURES...EXTENT OF WARM AIR
ADVECTION TOWARDS THE MIDDLE OF THE WEEK AND THE EXTENT OF COLD AIR
ADVECTION BEHIND THE NEXT WEATHER SYSTEM EXPECTED TO MOVE THROUGH.
AS THE WEEKEND WEATHER SYSTEM MOVES TO THE EAST...DRY WEATHER WILL
RETURN FOR MONDAY. TEMPERATURES SHOULD BE NEAR NORMAL AS A SURFACE
HIGH SETTLES IN FROM THE NORTH ACROSS THE PLAINS. WITH NORTHWEST
FLOW...WARMING SHOULD BE LIMITED AND DRIER AIR WILL FILTER IN.
NORTHWEST WINDS COULD BE BREEZY ON MONDAY AND WITH LOW RELATIVE
HUMIDITIES...FIRE WEATHER COULD BECOME A CONCERN IF PRECIPITATION IS
NOT RECEIVED WITH THIS SYSTEM.
WEAK UPPER LEVEL RIDGING WILL SET UP ACROSS THE PLAINS FOR TUESDAY
AND WEDNESDAY. THIS WILL LEAD TO DRY WEATHER CONTINUE AND A GRADUAL
WARMING TREND. SOUTH WINDS WILL RETURN...ALLOWING MOISTURE TO RETURN
TO THE REGION AHEAD OF THE NEXT WEATHER SYSTEM.
MODEL DIFFERENCES BECOME SIGNIFICANT WITH THE NEXT LONGWAVE TROUGH
TOWARDS THE END OF THE WEEK NEXT WEEK. MODELS TEND TO AGREE THAT A
DISTURBANCE OF SOME SORT WILL CROSS THE ROCKIES AND BEGIN ITS TREK
ACROSS THE PLAINS BY THURSDAY AND INTO FRIDAY. HOWEVER...THE
STRENGTH OF THIS SYSTEM IS VERY MUCH IN QUESTION. THE GFS IS MUCH
WARMER COMPARED TO THE EUROPEAN MODEL. IF THE EUROPEAN SOLUTION PANS
OUT...THE MAJORITY OF THE PRECIPITATION WITH THIS SYSTEM WILL BE
RAIN. THE GFS COUNTERS WITH RAIN THROUGHOUT THE FORECAST. HAVE TAKEN
THE MIDDLE ROAD WITH A SLIGHT LEAN TOWARDS THE GFS SINCE THE 00Z
EUROPEAN SOLUTION IS DRASTICALLY CHANGED FROM THE 12Z RUN.
THE GFS AND EUROPEAN ARE ALSO BEGINNING TO HINT AT NORTHERLY FLOW
ALOFT WITH AN ARCTIC HIGH PRESSURE MOVING SOUTH INTO THE HIGH PLAINS
FOR THE END OF NEXT WEEK AND INTO THE WEEKEND. IF THIS WERE TO
OCCUR...BELOW NORMAL TEMPERATURES CAN BE EXPECTED...POSSIBLY ON THE
ORDER OF 10 TO 15 DEGREES. CPC OUTLOOKS TEND TO FAVOR THE COLDER
SOLUTION SO HAVE NUDGED TEMPERATURES DOWN LATER IN THE EXTEND
FORECAST.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1000 PM MDT THU MAR 14 2013
FOR KGLD AND KMCK...VFR THROUGH THE PERIOD. SFC TROUGH TO MOVE
ACROSS THE AREA BY 12Z FRIDAY MORNING WITH NORTHWEST WINDS GUSTING
20-25KTS IN THE 19Z-23Z TIMEFRAME AT BOTH TERMINALS. WINDS WILL
BECOME NORTHEASTERLY AT 5-10KTS IN THE 01Z-03Z TIMEFRAME AS A COLD
FRONT MOVES THROUGH. CLOUDINESS LIMITED TO THE 18K-25K LEVEL
THROUGH THE PERIOD.
&&
.FIRE WEATHER...
ISSUED AT 221 AM MDT FRI MAR 15 2013
RECORD HIGH TEMPERATURES AND LOW TD VALUES IN THE TEENS WILL LEAD TO
LOW RH VALUES THIS AFTERNOON ACROSS THE CWA. WE SHOULD SEE RH VALUES
AROUND 10 PERCENT IN THE SOUTHWEST TO AROUND 15 PERCENT ACROSS OUR
NEBRASKA COUNTIES. GUIDANCE CONTINUES TO SHOW SOME INCREASE IN WINDS
ALOFT WITH UNIDIRECTIONAL FLOW...HOWEVER I AM NOT SURE WE ARE GOING
TO SEE THE THREE HOURS NECESSARY OF GUSTS AROUND 25MPH FOR A RED
FLAG WARNING IN THE NORTH...AND WINDS SHOULD BE LIGHTER IN THE SOUTH.
INCREASING CLOUDS FROM THE NORTHWEST COULD ALSO LEAD TO LESS MIXING
AND LIGHTER GUSTS. WITH TOO MUCH UNCERTAINTY REGARDING WINDS...I
DECIDED AGAINST ISSUING A RED FLAG WARNING...AND WILL ALLOW DAY
SHIFT TO MONITOR TRENDS.
&&
.CLIMATE...
ISSUED AT 810 PM MDT THU MAR 14 2013
THE FOLLOWING IS A LIST OF RECORD HIGH TEMPERATURES FOR FRIDAY
MARCH 15.
GOODLAND......82 IN 1935
HILL CITY.....84 IN 2003
MCCOOK........89 IN 1935
BURLINGTON....77 IN 1935
YUMA..........81
TRIBUNE.......84
COLBY.........86
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...RRH
AVIATION...99
FIRE WEATHER...DR
CLIMATE...DR
AREA FORECAST DISCUSSION...CORRECTED
NWS GOODLAND KS
234 AM MDT FRI MAR 15 2013
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 233 AM MDT FRI MAR 15 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW NW FLOW IN PLACE ACROSS
THE INTERMOUNTAIN WEST AND CENTRAL PLAINS WITH A RIDGE CENTERED
OVER SOUTHERN ARIZONA. AT THE SURFACE SEVERAL WEAK SURFACE TROUGHS
ARE IN PLACE OVER NW KANSAS AND EASTERN COLORADO.
H5 RIDGE IS EXPECTED TO CONTINUE TO WEAKEN WITH NW FLOW BECOMING
WESTERLY THIS AFTERNOON. WITH DEEP WESTERLY/DOWNSLOPE FLOW IN PLACE
ACROSS THE PLAINS WE WILL CONTINUE TO SEE WAA THROUGH THIS
AFTERNOON. CURRENTLY EXPECT NEAR RECORD HIGHS IN THE 80S ACROSS
MUCH OF THE CWA WITH SEVERAL LOCATIONS EXPECTED TO AT LEAST TIE
DAILY RECORDS.
A BACK DOOR COLD FRONT WILL DROP SOUTH OVER THE NORTHERN PLAINS AND
THROUGH THE CWA SATURDAY. SEASONAL TEMPERATURES WILL RETURN TO THIS
WEEKEND WITH HIGHS IN THE UPPER 40S TO MID 50S (COOLEST NORTHEAST-
WARMEST SOUTHWEST) AND OVERNIGHT LOWS NEAR FREEZING.
GUIDANCE CONTINUES TO SHOW SOME LIGHT QPF IN PLACE LATE TONIGHT
AFTER 06Z IN THE NORTHWEST SPREADING SOUTHEAST. HOWEVER...MODEL
SOUNDINGS CONTINUE TO SHOW A DRY LAYER BELOW 600MB THROUGH
SATURDAY MORNING...SO IM SKEPTICAL WHETHER WE WILL SEE MEASURABLE
TONIGHT. I LEFT 20 POPS IN PLACE TO ACCOUNT FOR POTENTIAL. BETTER
CHANCES SHOULD BE LATER IN THE DAY SATURDAY THROUGH SATURDAY NIGHT
AS LARGE SCALE FORCING AND WEAK INSTABILITY OVERSPREAD THE
REGION...WHEN A SHORTWAVE TROUGH MOVES ACROSS THE CENTRAL ROCKIES.
I INCREASE POPS TO LIKELY CATEGORY AROUND 00Z SAT THROUGH SAT
EVENING...WITH A DECREASING IN COVERAGE AFTER 06Z. A SECOND
STRONGER SHORTWAVE TROUGH WILL PASS THROUGH THE REGION
SUNDAY...WITH PRECIP CHANCES INCREASING ONCE AGAIN SUNDAY
AFTERNOON AND EVENING...BEFORE TAPERING OFF LATE SUNDAY NIGHT.
WITH TEMP PROFILES GENERALLY WARM THROUGH THE PERIOD WE SHOULD
MAINLY SEE RAIN AS THE PREDOMINATE PRECIP TYPE...THOUGH EARLY
SUNDAY MORNING AND LATE SUNDAY NIGHT WE COULD SEE A RAIN/SNOW
CHANGE OVER AND LIGHT SNOW ACCUMULATIONS. WITH WARM GROUND
TEMPERATURES AND THE BRIEF NATURE OF ANY CHANGE OVER...I AM NOT
SURE HOW MUCH SNOW ACCUMULATION WE WOULD ACTUALLY SEE. FOR NOW I
HAVE AROUND ONE HALF INCH OF LESS IN THE FORECAST FOR SAT
NIGHT...WITH ONLY A TRACE OF ACCUMULATION SUNDAY NIGHT.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 255 PM MDT THU MAR 14 2013
LONG TERM FOCUS IS ON COOLER TEMPERATURES AND THE POSSIBILITY OF
PRECIPITATION THROUGH THE WEEKEND.
THE UPPER FLOW CONTINUES TO FLATTEN AND BECOME MORE WESTERLY OVER
THE CENTRAL ROCKIES AND CENTRAL HIGH PLAINS FRIDAY NIGHT AND
SATURDAY. COLDER AIR MOVES INTO THE REGION FRIDAY NIGHT ALONG WITH
LIGHT RAIN AFTER MIDNIGHT FRIDAY NIGHT AND INTO SATURDAY MORNING
AS A COUPLE SHORT WAVE TROUGHS ALSO MOVE THROUGH THE UPPER FLOW
AND ACROSS THE REGION. THERE WILL BE A SOMEWHAT BETTER CHANCE OF
PRECIPITATION SATURDAY NIGHT AS A STRONGER UPPER SHORT WAVE TROUGH
MOVES THROUGH. THAT WAVE EXITS THE REGION BY MID DAY SUNDAY.
AM EXPECTING A DECREASE IN THE POSSIBILITY OF PRECIPITATION LATE
SUNDAY AS SUBSIDENCE BEHIND THE EXITING WAVE IS OVER THE OVERCAST
AREA TO BE FOLLOWED BY THE NEXT UPPER TROUGH TO MOVE THROUGH THE
FLOW. THE UPPER TROUGH IS NOW TAKING A MORE NORTHERLY TRACK AND IS
NOW MOVING THROUGH MAINLY THE NORTHEAST 1/2 OF THE FORECAST AREA.
HAVE MODIFIED AREA OF PRECIPITATION AND POPS TO REFLECT THIS LATE
SUNDAY THROUGH SUNDAY NIGHT.
ANOTHER RIDGE AMPLIFIES OVER THE WEST COAST AND MOVES EAST OVER THE
INTERMOUNTAIN REGION AND THE ROCKIES MONDAY AND TUESDAY. EXPECT
DRY CONDITIONS WITH TEMPERATURES GRADUALLY WARMING AGAIN THROUGH
THE MIDDLE OF THE WEEK AS THE RIDGE CONTINUES EAST OVER THE HIGH
PLAINS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1000 PM MDT THU MAR 14 2013
FOR KGLD AND KMCK...VFR THROUGH THE PERIOD. SFC TROUGH TO MOVE
ACROSS THE AREA BY 12Z FRIDAY MORNING WITH NORTHWEST WINDS GUSTING
20-25KTS IN THE 19Z-23Z TIMEFRAME AT BOTH TERMINALS. WINDS WILL
BECOME NORTHEASTERLY AT 5-10KTS IN THE 01Z-03Z TIMEFRAME AS A COLD
FRONT MOVES THROUGH. CLOUDINESS LIMITED TO THE 18K-25K LEVEL
THROUGH THE PERIOD.
&&
.FIRE WEATHER...
ISSUED AT 221 AM MDT FRI MAR 15 2013
RECORD HIGH TEMPERATURES AND LOW TD VALUES IN THE TEENS WILL LEAD TO
LOW RH VALUES THIS AFTERNOON ACROSS THE CWA. WE SHOULD SEE RH VALUES
AROUND 10 PERCENT IN THE SOUTHWEST TO AROUND 15 PERCENT ACROSS OUR
NEBRASKA COUNTIES. GUIDANCE CONTINUES TO SHOW SOME INCREASE IN WINDS
ALOFT WITH UNIDIRECTIONAL FLOW...HOWEVER I AM NOT SURE WE ARE GOING
TO SEE THE THREE HOURS NECESSARY OF GUSTS AROUND 25MPH FOR A RED
FLAG WARNING IN THE NORTH...AND WINDS SHOULD BE LIGHTER IN THE SOUTH.
INCREASING CLOUDS FROM THE NORTHWEST COULD ALSO LEAD TO LESS MIXING
AND LIGHTER GUSTS. WITH TOO MUCH UNCERTAINTY REGARDING WINDS...I
DECIDED AGAINST ISSUING A RED FLAG WARNING...AND WILL ALLOW DAY
SHIFT TO MONITOR TRENDS.
&&
.CLIMATE...
ISSUED AT 810 PM MDT THU MAR 14 2013
THE FOLLOWING IS A LIST OF RECORD HIGH TEMPERATURES FOR FRIDAY
MARCH 15.
GOODLAND......82 IN 1935
HILL CITY.....84 IN 2003
MCCOOK........89 IN 1935
BURLINGTON....77 IN 1935
YUMA..........81
TRIBUNE.......84
COLBY.........86
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...99
FIRE WEATHER...DR
CLIMATE...DR
AREA FORECAST DISCUSSION...UPDATED
NWS PITTSBURGH PA
920 PM EDT SAT MAR 16 2013
.SYNOPSIS...
PATCHY DRIZZLE AND FOG FOR THE REST OF THE EVENING...AS A COLD
FRONT SAGS SOUTH OF THE REGION. HIGH PRESSURE WILL BUILD OVERHEAD
BRIEFLY SUNDAY BEFORE STRONG LOW PRESSURE BRINGS THE CHANCE FOR
MIXED PRECIPITATION TO THE REGION SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
MINOR ADJUSTMENTS TO OVERNIGHT LOWS AND CLOUD COVER. HAVE REMOVED
MENTION OF DRIZZLE AND FOG WITH THE EXCEPTION OF THE HIGHEST
RIDGES...WHERE THE DRIER AIR HAS YET TO REACH.
PREVIOUS DISCUSSION...
SHOWERS ASSOCIATED WITH BOUNDARY CURRENTLY DRAPED OVER THE REGION
WILL CONTINUE TO SAG SOUTH THROUGH THE AFTERNOON. TEMPERATURES
HAVE REACHED THE MID TO UPPER 50`S OVER THE SOUTHERN HALF OF THE
COUNTY WARNING AREA WHILE TEMPERATURES REMAIN JUST AROUND FREEZING
TO THE NORTH. TEMPERATURES WILL BEGIN TO DECLINE AS THE DAY WEARS
ON AND COLD ADVECTION TAKES OVER. ADJUSTED THE DIURNAL CURVE BASED
OFF OF THE HRRR AND LAMP AS THESE GUIDANCE VALUES REPRESENTED THE
TEMPERATURE TREND QUITE WELL THIS MORNING.
HIGH PRESSURE WILL GRADUALLY BUILD SOUTHWARD BEHIND THE FRONT
OVERNIGHT. WITH NORTHWEST FLOW AND COLD ADVECTION CONTINUING...
THINK CLOUD COVER WILL REMAIN...WHICH SHOULD KEEP TEMPERATURES
FROM DROPPING TOO DRASTICALLY. AS SUCH...KEPT TEMPERATURES NEAR MOS
GUIDANCE.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
WHILE THE NEWEST RUNS OF THE DETERMINISTIC MODELS HAVE A BETTER
HANDLE ON THE PLACEMENT OF THE STATIONARY BOUNDARY ON
SUNDAY...INHERENT DIFFERENCES IN THE ATMOSPHERIC PROFILES CONTINUE
TO OWE TO LOW FORECAST CONFIDENCE. THE GFS AND NAM LINE UP BETTER
THAN THE PREVIOUS DAYS...BOTH BECOMING SIGNIFICANTLY COLDER AT THE
LOWER LEVELS. THIS HAS SIGNIFICANT IMPACT ON THE SNOW AND MIXED
PRECIPITATION FORECAST AS THE BOUNDARY LIFTS NORTHWARD AS A
WARM FRONT SUNDAY NIGHT. AS IT STANDS RIGHT NOW...MODEL PROFILES
HAVE A PROLONGED PERIOD OF SNOW/MIXED PRECIP ESPECIALLY IN THE
HIGHER ELEVATIONS OF WV/MD. HOWEVER...A LOT WILL DEPEND ON
TEMPERATURES....ESPECIALLY CONSIDERING HOW WARM THOSE LOCATIONS
GOT TODAY - MID 50`S AND HOW WARM WE GET DURING THE DAY SUNDAY
. AT THIS POINT...REMAINED CLOSE TO GUIDANCE FOR THE HIGH
TEMPERATURES SUNDAY BUT IF CLOUD COVER BREAKS AT ALL...WHICH IS
SUGGESTED IN ALL THE MODELS...THE WARM MARCH SUN COULD HAVE A
DRASTIC EFFECT ON LATER PRECIPITATION FORECASTS.
THE OTHER QUESTION IS THE EXTENT OF THE LOW LEVEL MIXING AND WARM
ADVECTION. AT THIS POINT...THERE SEEMS TO BE A BIT OF A COLD AIR
DAMMING SITUATION SUGGESTED BY ALL THE MODELS...LEADING TO
EASTERLY UPSLOPE FLOW OUT AHEAD OF THE APPROACHING SURFACE LOW
OVERNIGHT SUNDAY AND MONDAY MORNING. THIS COULD MAINTAIN SNOW IN
THE EASTERN FACING SLOPES WHILE THE WESTERN FACING SLOPES MAINLY
EXPERIENCE RAIN. IN ADDITION...WITH THE SLOWER PROGRESSION OF THE
FRONTAL BOUNDARY TO THE NORTH...THIS COULD GIVE POINTS NORTH OF
I-80 THAT REMAINED JUST NEAR FREEZING TODAY...TIME TO WARM BEFORE
ANY FROZEN PRECIPITATION COULD HAVE IMPACT. NEEDLESS TO SAY...THIS
IS A COMPLICATED FORECAST SITUATION...OWING TO SEVERAL FACTORS
NEEDING TO LINE UP FOR SNOW AND ICE TO HAVE THE IMPACT THIS LATE
IN THE SEASON. FOR NOW AND AFTER COORDINATION WITH OTHER LOCAL
OFFICES...HAVE MAINTAINED THE MENTION OF FREEZING RAIN AND SNOW
IN THE HAZARDOUS WEATHER OUTLOOK AND WILL LET FUTURE SHIFTS
EVALUATE WITH NEWER MODEL GUIDANCE.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
A DEEPENING TROUGH OVER THE NORTHERN PLAINS WILL SWING A COLD
FRONT ACROSS THE REGION BY EARLY TUESDAY. WITH BETTER CONFIDENCE
IN THE TIMING OF THIS SYSTEM...CONTINUED THE LIKELY POPS THROUGH
TUESDAY MORNING WITH RAIN QUICKLY CHANGING TO SNOW SHOWERS BEHIND
THE FRONTAL PASSAGE TUESDAY AFTERNOON. COLD NORTHWEST FLOW WILL
CONTINUE AT LEAST THE CHANCE FOR SNOW SHOWERS THROUGH TUESDAY
NIGHT. A DEEP UPPER LEVEL TROUGH WILL REMAIN OVER THE EASTERN
CONUS THROUGH THE REST OF THE WEEK KEEPING TEMPERATURES BELOW
SEASONAL AVERAGES THROUGH THE REST OF THE PERIOD.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
A SLOW MOVING EAST WEST FRONT HAS PUSHED SOUTH OF KPIT AND KAGC AND
WILL CONTINUE SAGGING SOUTH OVERNIGHT. BEHIND THE FRONT IS WIDESPREAD
IFR STRATUS OVERCAST AND SOME IFR VSBY NEAR THE FRONTAL BOUNDARY WITH
SOME DENSE FOG. AS THE FRONT CONTINUES SOUTH VSBY WILL IMPROVE NORTH
OF THE FRONT WITH DRIER AIR PUSHING IN AT THE LOW LEVELS...BUT THE
STRATUS CEILINGS WILL CONTINUE AND ONLY SLOW RISE TOWARD DAYBREAK.
SOME WIND GUSTS OUT OF THE NORTHWEST OF 15 TO 20 KNOTS ARE POSSIBLE
BRIEFLY BEHIND THE FRONT. SOME LIGHT RAIN OR DRIZZLE IS LIKELY
WITH THE FROPA AS WELL.
IFR CEILINGS WILL LIFT MVFR CEILINGS WILL FINALLY LIFT TO VFR AS
HIGH PRESSURE BUILDS IN FROM THE NORTHWEST ON SUNDAY.
.OUTLOOK.../SUNDAY THROUGH THURSDAY/...
RESTRICTIONS ARE POSSIBLE ALONG WITH A WINTRY MIX OF
RAIN...SNOW...AND FREEZING RAIN EARLY MONDAY. PRECIPITATION WILL
CHANGE TO ALL RAIN ON MONDAY BEFORE A COLD FRONT USHERS COLDER AIR IN
FROM THE NORTHWEST AND ALLOWS FOR PRECIPITATION TO CHANGE OVER TO
SNOW SHOWERS MONDAY NIGHT. A NORTHWESTERLY FLOW IN THE WAKE OF THE
FRONT WILL THEN ALLOW FOR CEILINGS RESTRICTIONS WITH THE SLIGHT
CHANCE OF RAIN AND SNOW SHOWERS TUESDAY INTO THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
732 PM EDT SAT MAR 16 2013
.SYNOPSIS...
PATCHY DRIZZLE AND FOG FOR THE REST OF THE EVENING...AS A COLD
FRONT SAGS SOUTH OF THE REGION. HIGH PRESSURE WILL BUILD OVERHEAD
BRIEFLY SUNDAY BEFORE STRONG LOW PRESSURE BRINGS THE CHANCE FOR
MIXED PRECIPITATION TO THE REGION SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
HAVE UPDATED TO MAKE ADJUSTMENTS TO OVERNIGHT LOWS...SKEWED TOWARD
LATEST LAMP NUMBERS. ALSO ADDED THEM MENTION OF DRIZZLE AND FOG
FOR THE EVENING...WITH DENSE FOG IN THE HIGHER ELEVATIONS.
PREVIOUS DISCUSSION...
SHOWERS ASSOCIATED WITH BOUNDARY CURRENTLY DRAPED OVER THE REGION
WILL CONTINUE TO SAG SOUTH THROUGH THE AFTERNOON. TEMPERATURES
HAVE REACHED THE MID TO UPPER 50`S OVER THE SOUTHERN HALF OF THE
COUNTY WARNING AREA WHILE TEMPERATURES REMAIN JUST AROUND FREEZING
TO THE NORTH. TEMPERATURES WILL BEGIN TO DECLINE AS THE DAY WEARS
ON AND COLD ADVECTION TAKES OVER. ADJUSTED THE DIURNAL CURVE BASED
OFF OF THE HRRR AND LAMP AS THESE GUIDANCE VALUES REPRESENTED THE
TEMPERATURE TREND QUITE WELL THIS MORNING.
HIGH PRESSURE WILL GRADUALLY BUILD SOUTHWARD BEHIND THE FRONT
OVERNIGHT. WITH NORTHWEST FLOW AND COLD ADVECTION CONTINUING...
THINK CLOUD COVER WILL REMAIN...WHICH SHOULD KEEP TEMPERATURES
FROM DROPPING TOO DRASTICALLY. AS SUCH...KEPT TEMPERATURES NEAR MOS
GUIDANCE.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
WHILE THE NEWEST RUNS OF THE DETERMINISTIC MODELS HAVE A BETTER
HANDLE ON THE PLACEMENT OF THE STATIONARY BOUNDARY ON
SUNDAY...INHERENT DIFFERENCES IN THE ATMOSPHERIC PROFILES CONTINUE
TO OWE TO LOW FORECAST CONFIDENCE. THE GFS AND NAM LINE UP BETTER
THAN THE PREVIOUS DAYS...BOTH BECOMING SIGNIFICANTLY COLDER AT THE
LOWER LEVELS. THIS HAS SIGNIFICANT IMPACT ON THE SNOW AND MIXED
PRECIPITATION FORECAST AS THE BOUNDARY LIFTS NORTHWARD AS A
WARM FRONT SUNDAY NIGHT. AS IT STANDS RIGHT NOW...MODEL PROFILES
HAVE A PROLONGED PERIOD OF SNOW/MIXED PRECIP ESPECIALLY IN THE
HIGHER ELEVATIONS OF WV/MD. HOWEVER...A LOT WILL DEPEND ON
TEMPERATURES....ESPECIALLY CONSIDERING HOW WARM THOSE LOCATIONS
GOT TODAY - MID 50`S AND HOW WARM WE GET DURING THE DAY SUNDAY
. AT THIS POINT...REMAINED CLOSE TO GUIDANCE FOR THE HIGH
TEMPERATURES SUNDAY BUT IF CLOUD COVER BREAKS AT ALL...WHICH IS
SUGGESTED IN ALL THE MODELS...THE WARM MARCH SUN COULD HAVE A
DRASTIC EFFECT ON LATER PRECIPITATION FORECASTS.
THE OTHER QUESTION IS THE EXTENT OF THE LOW LEVEL MIXING AND WARM
ADVECTION. AT THIS POINT...THERE SEEMS TO BE A BIT OF A COLD AIR
DAMMING SITUATION SUGGESTED BY ALL THE MODELS...LEADING TO
EASTERLY UPSLOPE FLOW OUT AHEAD OF THE APPROACHING SURFACE LOW
OVERNIGHT SUNDAY AND MONDAY MORNING. THIS COULD MAINTAIN SNOW IN
THE EASTERN FACING SLOPES WHILE THE WESTERN FACING SLOPES MAINLY
EXPERIENCE RAIN. IN ADDITION...WITH THE SLOWER PROGRESSION OF THE
FRONTAL BOUNDARY TO THE NORTH...THIS COULD GIVE POINTS NORTH OF
I-80 THAT REMAINED JUST NEAR FREEZING TODAY...TIME TO WARM BEFORE
ANY FROZEN PRECIPITATION COULD HAVE IMPACT. NEEDLESS TO SAY...THIS
IS A COMPLICATED FORECAST SITUATION...OWING TO SEVERAL FACTORS
NEEDING TO LINE UP FOR SNOW AND ICE TO HAVE THE IMPACT THIS LATE
IN THE SEASON. FOR NOW AND AFTER COORDINATION WITH OTHER LOCAL
OFFICES...HAVE MAINTAINED THE MENTION OF FREEZING RAIN AND SNOW
IN THE HAZARDOUS WEATHER OUTLOOK AND WILL LET FUTURE SHIFTS
EVALUATE WITH NEWER MODEL GUIDANCE.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
A DEEPENING TROUGH OVER THE NORTHERN PLAINS WILL SWING A COLD
FRONT ACROSS THE REGION BY EARLY TUESDAY. WITH BETTER CONFIDENCE
IN THE TIMING OF THIS SYSTEM...CONTINUED THE LIKELY POPS THROUGH
TUESDAY MORNING WITH RAIN QUICKLY CHANGING TO SNOW SHOWERS BEHIND
THE FRONTAL PASSAGE TUESDAY AFTERNOON. COLD NORTHWEST FLOW WILL
CONTINUE AT LEAST THE CHANCE FOR SNOW SHOWERS THROUGH TUESDAY
NIGHT. A DEEP UPPER LEVEL TROUGH WILL REMAIN OVER THE EASTERN
CONUS THROUGH THE REST OF THE WEEK KEEPING TEMPERATURES BELOW
SEASONAL AVERAGES THROUGH THE REST OF THE PERIOD.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
A SLOW MOVING EAST WEST FRONT HAS PUSHED SOUTH OF KPIT AND KAGC AND
WILL CONTINUE SAGGING SOUTH OVERNIGHT. BEHIND THE FRONT IS WIDESPREAD
IFR STRATUS OVERCAST AND SOME IFR VSBY NEAR THE FRONTAL BOUNDARY WITH
SOME DENSE FOG. AS THE FRONT CONTINUES SOUTH VSBY WILL IMPROVE NORTH
OF THE FRONT WITH DRIER AIR PUSHING IN AT THE LOW LEVELS...BUT THE
STRATUS CEILINGS WILL CONTINUE AND ONLY SLOW RISE TOWARD DAYBREAK.
SOME WIND GUSTS OUT OF THE NORTHWEST OF 15 TO 20 KNOTS ARE POSSIBLE
BRIEFLY BEHIND THE FRONT. SOME LIGHT RAIN OR DRIZZLE IS LIKELY
WITH THE FROPA AS WELL.
IFR CEILINGS WILL LIFT MVFR CEILINGS WILL FINALLY LIFT TO VFR AS
HIGH PRESSURE BUILDS IN FROM THE NORTHWEST ON SUNDAY.
.OUTLOOK.../SUNDAY THROUGH THURSDAY/...
RESTRICTIONS ARE POSSIBLE ALONG WITH A WINTRY MIX OF
RAIN...SNOW...AND FREEZING RAIN EARLY MONDAY. PRECIPITATION WILL
CHANGE TO ALL RAIN ON MONDAY BEFORE A COLD FRONT USHERS COLDER AIR IN
FROM THE NORTHWEST AND ALLOWS FOR PRECIPITATION TO CHANGE OVER TO
SNOW SHOWERS MONDAY NIGHT. A NORTHWESTERLY FLOW IN THE WAKE OF THE
FRONT WILL THEN ALLOW FOR CEILINGS RESTRICTIONS WITH THE SLIGHT
CHANCE OF RAIN AND SNOW SHOWERS TUESDAY INTO THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
131 PM EDT FRI MAR 15 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 458 AM EDT FRI MAR 15 2013
COLD FRONT HAS JUST SLIDE THROUGH NORTH CENTRAL UPPER MICHIGAN
/WITH A QUICK WIND SHIFT TO THE NORTH/ AND WILL CONTINUE TO THE
SOUTH-SOUTHEAST AND EXIT UPPER MICHIGAN AROUND 12Z. WITH MUCH OF
THE DEEPER MOISTURE DEPARTING EARLIER IN THE EVENING...SNOW SHOWERS
HAVE QUICKLY DIMINISHED ACROSS THE AREA AND THERE HAVE EVEN BEEN
SOME BREAKS IN THE CLOUDS OVER THE NORTHEAST HALF OF LAKE SUPERIOR
BEHIND THE FRONT. BUT...AS COLDER AIR AS STARTED TO MOVE SOUTH
ACROSS THE LAKE /RAP ANALYZED 850MB TEMPS FALLING TO -13C/ THERE
HAVE BEEN LAKE EFFECT CLOUDS REDEVELOPING FROM NORTH TO SOUTH.
BEHIND THE TROUGH THAT HAS MOVED THROUGH THIS MORNING...HIGH
PRESSURE RIDGE FROM A PARENT HIGH OVER NORTHERN ALBERTA WILL MOVE
OVER LAKE SUPERIOR AND PROVIDE LIGHT NORTHERLY WINDS TO THE AREA.
THIS NORTHERLY FLOW...COMBINED WITH 875MB TEMPS AROUND -16C
WILL PROVIDE PLENTY OF OVER LAKE INSTABILITY AND COULD PRODUCE A FEW
LIGHT LAKE EFFECT/ENHANCED SNOW SHOWERS OVER THE NORTH CENTRAL CWA.
THERE ARE A COUPLE LIMITING FACTORS TO THE STRENGTH AND CHANCES.
FIRST...DRY AIR FROM 875-650MB WILL AID IN LOWERING THE INVERSION TO
3-3.5KFT TODAY. ALSO...WITH THE HIGH PRESSURE MOVING IN...FLOW WILL
BECOME ANTICYCLONIC/DIVERGENT THROUGH THE DAY. THEREFORE...THINK THE
BEST CHANCES WILL BE DURING THE FIRST PART OF THE MORNING HOURS AND
THEN DIMINISH FROM NORTH TO SOUTH AS THE DRIER AIR ARRIVES. DID
LEAVE THE MENTION OF FREEZING DRIZZLE IN OVER THE FAR WEST EARLY
THIS MORNING...DUE TO RAP SOUNDINGS SHOWING THE MORE MARGINAL ICE
PRESENCE THERE.
FARTHER SOUTH TODAY...THE FIRST OF TWO SHORTWAVES MOVING FROM THE
NORTHERN PLAINS TO THE LOWER GREAT LAKES WILL BRUSH THE CWA. AT
THIS TIME...WITH THE SURFACE TROUGH FROM THIS MORNING SLIDING WELL
SOUTH OF THE AREA AND THE WEST-NORTHWEST TO EAST-SOUTHEAST
ORIENTATED ISOTHERMS FROM 850-700MB SETUP FROM CENTRAL MINNESOTA TO
SOUTHEAST WISCONSIN...WOULD EXPECT THE BULK OF THE PRECIPITATION TO
ALIGN WITH THAT AREA. THEREFORE...HAVE CONTINUED THE REDUCTION TO
POPS AND HAVE DROPPED MENTION OF SNOW FROM AREAS NEAR THE WISCONSIN
BORDER EXCEPT FOR THE LAKE INFLUENCE NEAR IRONWOOD.
OVERALL...OTHER THAN A FEW BREAKS IN THE CLOUDS BEHIND THE
TROUGH...EXPECT A MAINLY CLOUDY DAY WITH THE COMBINED LAKE
INFLUENCE AND ADDITIONAL MID/HIGH CLOUDS FROM THE SYSTEM TO THE
SOUTH. WON/T BE MUCH REBOUND TO THE DAYBREAK TEMPERATURES OVER THE
NORTH AS THE COLDER AIR SURGES SOUTH ACROSS THE AREA BEHIND THE
COLD FRONT. THIS WILL LIKELY LEAD TO TEMPERATURES SLOWLY FALLING IN
THE AFTERNOON AND HAVE ADDED THAT TO THE FORECAST. ALL IN ALL...NOT
REALLY MARCH LIKE WEATHER FOR LOCATIONS NEAR LAKE SUPERIOR TODAY
WITH THE NORTHERLY WINDS OFF THE LAKE PRODUCING WIND CHILLS IN THE
SINGLE DIGITS FOR A GOOD PORTION OF THE DAY.
THEN FOR TONIGHT...THE SECOND SHORTWAVE WILL DROPS SOUTHEAST ALONG
A SIMILAR PATH...BUT THE LATEST TRENDS IN THE GLOBAL MODELS HAVE IT
BEING A TOUCH FARTHER TO THE NORTH. THAT BEING SAID...THE NAM SHOWS
IT TRACKING FARTHER SOUTH AND SIMILAR TO TODAY WAVE...WHICH CAUSES
SEVERAL OF THE HIGHER RESOLUTION RUNS THAT ARE BASED OFF THE NAM/S
INITIALIZATION TO FOLLOW SUIT. AGAIN...THE BEST THERMAL GRADIENT
WILL LIKELY BE TO THE SOUTH OF THE AREA...BUT WITH THE TRACK OF THE
SHORTWAVE AND DEEPER MOISTURE OVER THE AREA...FEEL COMFORTABLE
MENTIONING SCATTERED SNOW SHOWERS ALONG THE SOUTHWEST THIRD OF THE
CWA WITH THE HIGHEST AMOUNTS /NEAR AN INCH/ NEAR THE WISCONSIN
BORDER.
FARTHER TO THE NORTH...WITH THE INCREASING MOISTURE AND H850 TEMPS
AROUND -18C...THERE IS AMPLE LAKE INDUCED INSTABILITY FOR LAKE
EFFECT SNOW SHOWERS. HAVE TRENDED POPS UP FOR THE NORTH
CENTRAL...ESPECIALLY AFTER 06Z WHEN 1000-850MB LAPSE RATES APPROACH
8C/KM AND THERE IS SOME INCREASED CONVERGENCE IN THE LOW LEVEL
FLOW. WOULDN/T EXPECT SNOW AMOUNTS TO GET TOO OUT OF CONTROL...DUE
TO SHEAR FROM WINDS ABOVE 850MB BEING OUT OF THE WNW AND THE LOW
LEVELS OUT OF THE NNE. BUT WITH MUCH OF THE CLOUD LAYER WITHIN THE
DGZ...COULD SEE A FLUFFY INCH OR MAYBE TWO OVER THE HIGHER TERRAIN
OF MARQUETTE OR BARAGA COUNTY /HURON MOUNTAINS/. THERE ARE A FEW
HIGHER RESOLUTION MODELS THAT ARE SHOWING AMOUNTS TOWARDS 3
INCHES...SO IT WILL BE SOMETHING TO WATCH FOR FUTURE SHIFTS.
ELSEWHERE...WIND FIELD IS MORE VARIABLE OVER THE WEST AND
LESS FAVORABLE FOR LAKE EFFECT SNOW...BUT WILL MENTION SOME SNOW DUE
TO THE SYNOPTIC FORCING.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 458 AM EDT FRI MAR 15 2013
DURING THE LONG TERM...IT APPEARS BELOW NORMAL TEMPS WILL BE THE
RULE DUE TO HIGH LATITUDE BLOCKING/NEGATIVE NAO. THE MJO REMAINS
ACTIVE AS IT HAS FOR AT LEAST THE LAST 2 MONTHS. ITS FORECASTED
PHASE INITIALLY FAVORS WARMTH FOR THE ERN CONUS...BUT WILL TEND TO
FAVOR BELOW NORMAL TEMPS HEADING INTO THE END OF MAR. FOR THE TIME
BEING...THE HIGH LATITUDE BLOCKING WILL BE THE PRIMARY DRIVER...BUT
SHOULD THAT BREAK DOWN...THE MJO PHASE WILL BECOME MORE IMPORTANT.
IN THE END...THIS POINTS TO BELOW NORMAL TEMPS LIKELY BEING THE RULE
THRU THE END OF THE MONTH...EITHER BY HIGH LATITUDE BLOCKING OR MJO.
THE PATTERN SHOULD BE AN ACTIVE ONE...MAINLY DURING THE FIRST HALF
OR SO OF THIS LONG TERM PERIOD. FARTHER DOWN THE ROAD...LONG RANGE
GFS RUNS HAVE BEEN SUGGESTING THERE MAY CONTINUE TO BE AN ACTIVE
STORM TRACK ACROSS THE CONUS BEYOND THIS 7 DAY FCST. WITH EXPECTED
BELOW NORMAL TEMPS...MORE SNOW EVENTS MAY BE ON THE WAY AS WE HEAD
THRU LATE MAR.
BEGINNING SAT/SAT NIGHT...WITH HIGH LATITUDE POSITIVE HEIGHT
ANOMALIES OVER GREENLAND AND N OF ALASKA...A W-E ELONGATED POLAR
VORTEX WILL DOMINATE MUCH OF CANADA WITH CENTER OVER HUDSON BAY. IN
THE MORNING...A SHORTWAVE TROF WILL EXTEND FROM THE CENTER TO SRN
MANITOBA/SASKATCHEWAN. THIS WAVE WILL QUICKLY SWING THRU THE UPPER
LAKES SAT EVENING. WITH TRACK OF VORT MAX JUST N OF UPPER MI...
BETTER SNOW POTENTIAL WILL LIKELY PASS BY TO THE N. THAT SAID...
850MB TEMPS ACROSS LAKE SUPERIOR ARE PROGGED TO BE BTWN -16 AND
-20C...NORMALLY INDICATING THAT THERE WILL BE A PERIOD OF HVY LAKE
ENHANCED SNOW WITH COLD FROPA. IN THIS CASE...FCST SOUNDINGS SHOW A
WELL MIXED LAYER WHICH WILL BE A NEGATIVE. ON THE OTHER HAND...
VIGOROUS UPWARD MOTION IS FCST THRU A ROUGHLY 3KFT DGZ WITH
INVERSION BASE UP AROUND 8-9KFT. SO...STILL MAY END UP WITH A VERY
BRIEF PERIOD OF MDT/HVY SNOW WITH FROPA ACROSS THE N...ESPECIALLY
THE NW FCST AREA AND AREAS E OF MARQUETTE. EVEN INLAND MAY SEE SOME
RATHER VIGOROUS -SHSN FOR A BRIEF TIME GIVEN STEEP LOW-LEVEL LAPSE
RATES WITH UPWARD MOTION MAX INTERSECTING DGZ...THOUGH DRY AIR WILL
KEEP COVERAGE LOW. AFTER FROPA LATE SAT AFTN/EVENING...INVERSION
FALLS TO 4-5KFT SAT NIGHT. LOWERING INVERSION AND A CONTINUED
WELL-MIXED LAYER WILL WORK TO KEEP LES IN CHECK DESPITE 850MB TEMPS
FALLING TO AROUND -20C. DGZ DOES REMAIN FAVORABLY POSITIONED IN
CONVECTIVE LAYER...SO THERE SHOULD BE LIGHT ACCUMULATIONS OF FLUFFY
SNOW UNDER ADVY CRITERIA. GREATEST ACCUMULATIONS WILL BE OVER THE E
WHERE LONGER FETCH ACROSS LAKE SUPERIOR WILL WORK TO MOISTEN THE
LOW-LEVELS.
SUN...SFC HIGH PRES WILL SLIDE ACROSS THE UPPER LAKES. LINGERING
LES NEAR LAKE SUPERIOR WILL END...PROBABLY NO LATER THAN EARLY AFTN
AS COMBINATION OF NEGATIVE DYNAMICS/INCREASING ANTICYCLONIC
FLOW/DRYING/DAYTIME HEATING WITH INCREASING MARCH INSOLATION
DISRUPTS THE LES PROCESS. IN FACT...THE DAY IS LIKELY TO TURN MOSTLY
SUNNY IN THE AFTN W-E WITH WSHFT TO THE S FOLLOWING PASSAGE OF HIGH
PRES RDG AXIS. DESPITE INCREASING SUNSHINE...THE DAY WILLL FEATURE
BLO NORMAL MAX TEMPS MAINLY IN THE 20S WITH 850MB TEMPS RECOVERING
TO -12C TO -14C IN THE AFTN. QUIET WEATHER SHOULD LINGER THRU SUN
NIGHT.
FOR A FEW DAYS NOW...MEDIUM RANGE GUIDANCE HAS BEEN INDICATING THE
POTENTIAL FOR A WINTER STORM IN THE GREAT LAKES REGION MON/TUE.
SCENARIO IS FAR FROM CERTAIN DUE TO COMPLICATED PHASING ISSUES...
LEAVING TIMING AND LOCATION OF PHASING SYSTEM UNCERTAIN. MODELS HAVE
BEEN AND CONTINUE TO STRUGGLE WITH THE DETAILS. BASED ON TODAYS 00Z
AND YESTERDAYS 12Z RUNS...THE GENERAL THEME OF GUIDANCE IS FOR
PHASING TO OCCUR OVER THE GREAT LAKES...BUT PROBABLY A LITTLE TOO
FAR E TO BRING A WIDESPREAD HVY SNOW EVENT TO UPPER MI. HOWEVER...
GIVEN THE PHASING UNCERTAINTIES...MUCH COULD STILL CHANGE IN THE
NEXT FEW DAYS. CONFIDENCE IS A LITTLE HIGHER FOR HEAVIER SNOW NEAR
LAKE SUPERIOR AS LAKE ENHANCEMENT POTENTIAL LOOKS GOOD DUE TO
DEEPENING MIDLEVEL LOW OVER THE GREAT LAKES AND DEEP CYCLONIC FLOW
AFFECTING UPPER MI/LAKE SUPERIOR. LOW-LEVEL WIND DIRECTION IS AND
WILL CONTINUE TO BE THE IMPORTANT UNCERTAIN POINT...BUT AT THIS
TIME...GUIDANCE GENERALLY INDICATES MID LEVEL LOW CLOSING OFF N OR
NE OF THE AREA. THIS WOULD SUGGEST AREAS FAVORED BY NW WINDS WILL
SEE MAJORITY OF LAKE ENHANCEMENT. LIKELY POPS WILL CONTINUE TO
UTILIZED FOR THIS EVENT WITH PRIME SYNOPTIC SNOW PERIOD PROBABLY MON
AFTN/EVENING...AND THEN MAIN LAKE ENHANCEMENT PERIOD LATE MON NIGHT
THRU TUE.
BEHIND THE SYSTEM...LES WILL PROBABLY CONTINUE THRU WED UNDER
LINGERING MID LEVEL TROFFING WITH 850MB TEMPS AROUND -15C. THEN ON
THU...SYSTEM SHOULD BE FAR ENOUGH TO THE E TO ALLOW THE COMBINATION
OF RISING HEIGHTS/DRYING AND MARCH INSOLATION TO BRING AN END TO
MUCH OF THE LES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 130 PM EDT FRI MAR 15 2013
EXPECT LAKE EFFECT SNOW SHOWERS TO TAPER OFF QUICKLY AT IWD AND CMX
THIS AFTERNOON...WHILE CONTINUING AT SAW. A DISTURBANCE WILL MOVE
THROUGH TONIGHT...BRINGING CHANCES FOR SNOW TO ALL SITES. IN
GENERAL...MVFR CONDITIONS SHOULD BE MOST COMMON TONIGHT...WITH THE
BEST CHANCE AT GETTING TO IFR CONDITIONS AT SAW WHERE LAKE
ENHANCEMENT WILL HELP INTENSIFY SNOW SHOWERS. CONDITIONS SHOULD
IMPROVE LATE IN THE TAF PERIOD AS WINDS BECOME OUT OF THE S AND BEST
LOW LEVEL MOISTURE DEPARTS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 458 AM EDT FRI MAR 15 2013
AFTER A FEW GALE FORCE GUSTS TO 35KTS IMMEDIATELY BEHIND THE COLD
FRONT MOVING THROUGH EARLY THIS MORNING...WINDS WILL SLOWLY
DECREASE BELOW 25 KNOTS THIS AFTERNOON AND STAY OUT OF A NORTHERLY
DIRECTION INTO SATURDAY. ANOTHER TROUGH WILL CUT THROUGH THE HIGH
PRESSURE RIDGE AND SLIDE ACROSS LAKE SUPERIOR ON SATURDAY EVENING.
BEHIND THE TROUGH...THERE WILL BE A FEW GALE FORCE GUSTS TO 35KTS
OVER THE CENTRAL/EASTERN LAKE AND THERE IS ALSO THE POTENTIAL FOR
HEAVY FREEZING SPRAY. HIGH PRESSURE WILL THEN SETTLE BACK OVER THE
AREA FOR SUNDAY INTO SUNDAY NIGHT AND LEAD TO LIGHT WINDS. A LOW
PRESSURE SYSTEM EXITING THE NORTHERN PLAINS ON SUNDAY NIGHT WILL MOVE
INTO THE GREAT LAKES REGION FOR MONDAY NIGHT INTO TUESDAY. WINDS WILL
BE ON THE INCREASE AS THIS SYSTEM CROSSES THE REGION...WITH SOME
PERIODS OF WINDS UP TO 30KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...TITUS
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
740 AM EDT FRI MAR 15 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 458 AM EDT FRI MAR 15 2013
COLD FRONT HAS JUST SLIDE THROUGH NORTH CENTRAL UPPER MICHIGAN
/WITH A QUICK WIND SHIFT TO THE NORTH/ AND WILL CONTINUE TO THE
SOUTH-SOUTHEAST AND EXIT UPPER MICHIGAN AROUND 12Z. WITH MUCH OF
THE DEEPER MOISTURE DEPARTING EARLIER IN THE EVENING...SNOW SHOWERS
HAVE QUICKLY DIMINISHED ACROSS THE AREA AND THERE HAVE EVEN BEEN
SOME BREAKS IN THE CLOUDS OVER THE NORTHEAST HALF OF LAKE SUPERIOR
BEHIND THE FRONT. BUT...AS COLDER AIR AS STARTED TO MOVE SOUTH
ACROSS THE LAKE /RAP ANALYZED 850MB TEMPS FALLING TO -13C/ THERE
HAVE BEEN LAKE EFFECT CLOUDS REDEVELOPING FROM NORTH TO SOUTH.
BEHIND THE TROUGH THAT HAS MOVED THROUGH THIS MORNING...HIGH
PRESSURE RIDGE FROM A PARENT HIGH OVER NORTHERN ALBERTA WILL MOVE
OVER LAKE SUPERIOR AND PROVIDE LIGHT NORTHERLY WINDS TO THE AREA.
THIS NORTHERLY FLOW...COMBINED WITH 875MB TEMPS AROUND -16C
WILL PROVIDE PLENTY OF OVER LAKE INSTABILITY AND COULD PRODUCE A FEW
LIGHT LAKE EFFECT/ENHANCED SNOW SHOWERS OVER THE NORTH CENTRAL CWA.
THERE ARE A COUPLE LIMITING FACTORS TO THE STRENGTH AND CHANCES.
FIRST...DRY AIR FROM 875-650MB WILL AID IN LOWERING THE INVERSION TO
3-3.5KFT TODAY. ALSO...WITH THE HIGH PRESSURE MOVING IN...FLOW WILL
BECOME ANTICYCLONIC/DIVERGENT THROUGH THE DAY. THEREFORE...THINK THE
BEST CHANCES WILL BE DURING THE FIRST PART OF THE MORNING HOURS AND
THEN DIMINISH FROM NORTH TO SOUTH AS THE DRIER AIR ARRIVES. DID
LEAVE THE MENTION OF FREEZING DRIZZLE IN OVER THE FAR WEST EARLY
THIS MORNING...DUE TO RAP SOUNDINGS SHOWING THE MORE MARGINAL ICE
PRESENCE THERE.
FARTHER SOUTH TODAY...THE FIRST OF TWO SHORTWAVES MOVING FROM THE
NORTHERN PLAINS TO THE LOWER GREAT LAKES WILL BRUSH THE CWA. AT
THIS TIME...WITH THE SURFACE TROUGH FROM THIS MORNING SLIDING WELL
SOUTH OF THE AREA AND THE WEST-NORTHWEST TO EAST-SOUTHEAST
ORIENTATED ISOTHERMS FROM 850-700MB SETUP FROM CENTRAL MINNESOTA TO
SOUTHEAST WISCONSIN...WOULD EXPECT THE BULK OF THE PRECIPITATION TO
ALIGN WITH THAT AREA. THEREFORE...HAVE CONTINUED THE REDUCTION TO
POPS AND HAVE DROPPED MENTION OF SNOW FROM AREAS NEAR THE WISCONSIN
BORDER EXCEPT FOR THE LAKE INFLUENCE NEAR IRONWOOD.
OVERALL...OTHER THAN A FEW BREAKS IN THE CLOUDS BEHIND THE
TROUGH...EXPECT A MAINLY CLOUDY DAY WITH THE COMBINED LAKE
INFLUENCE AND ADDITIONAL MID/HIGH CLOUDS FROM THE SYSTEM TO THE
SOUTH. WON/T BE MUCH REBOUND TO THE DAYBREAK TEMPERATURES OVER THE
NORTH AS THE COLDER AIR SURGES SOUTH ACROSS THE AREA BEHIND THE
COLD FRONT. THIS WILL LIKELY LEAD TO TEMPERATURES SLOWLY FALLING IN
THE AFTERNOON AND HAVE ADDED THAT TO THE FORECAST. ALL IN ALL...NOT
REALLY MARCH LIKE WEATHER FOR LOCATIONS NEAR LAKE SUPERIOR TODAY
WITH THE NORTHERLY WINDS OFF THE LAKE PRODUCING WIND CHILLS IN THE
SINGLE DIGITS FOR A GOOD PORTION OF THE DAY.
THEN FOR TONIGHT...THE SECOND SHORTWAVE WILL DROPS SOUTHEAST ALONG
A SIMILAR PATH...BUT THE LATEST TRENDS IN THE GLOBAL MODELS HAVE IT
BEING A TOUCH FARTHER TO THE NORTH. THAT BEING SAID...THE NAM SHOWS
IT TRACKING FARTHER SOUTH AND SIMILAR TO TODAY WAVE...WHICH CAUSES
SEVERAL OF THE HIGHER RESOLUTION RUNS THAT ARE BASED OFF THE NAM/S
INITIALIZATION TO FOLLOW SUIT. AGAIN...THE BEST THERMAL GRADIENT
WILL LIKELY BE TO THE SOUTH OF THE AREA...BUT WITH THE TRACK OF THE
SHORTWAVE AND DEEPER MOISTURE OVER THE AREA...FEEL COMFORTABLE
MENTIONING SCATTERED SNOW SHOWERS ALONG THE SOUTHWEST THIRD OF THE
CWA WITH THE HIGHEST AMOUNTS /NEAR AN INCH/ NEAR THE WISCONSIN
BORDER.
FARTHER TO THE NORTH...WITH THE INCREASING MOISTURE AND H850 TEMPS
AROUND -18C...THERE IS AMPLE LAKE INDUCED INSTABILITY FOR LAKE
EFFECT SNOW SHOWERS. HAVE TRENDED POPS UP FOR THE NORTH
CENTRAL...ESPECIALLY AFTER 06Z WHEN 1000-850MB LAPSE RATES APPROACH
8C/KM AND THERE IS SOME INCREASED CONVERGENCE IN THE LOW LEVEL
FLOW. WOULDN/T EXPECT SNOW AMOUNTS TO GET TOO OUT OF CONTROL...DUE
TO SHEAR FROM WINDS ABOVE 850MB BEING OUT OF THE WNW AND THE LOW
LEVELS OUT OF THE NNE. BUT WITH MUCH OF THE CLOUD LAYER WITHIN THE
DGZ...COULD SEE A FLUFFY INCH OR MAYBE TWO OVER THE HIGHER TERRAIN
OF MARQUETTE OR BARAGA COUNTY /HURON MOUNTAINS/. THERE ARE A FEW
HIGHER RESOLUTION MODELS THAT ARE SHOWING AMOUNTS TOWARDS 3
INCHES...SO IT WILL BE SOMETHING TO WATCH FOR FUTURE SHIFTS.
ELSEWHERE...WIND FIELD IS MORE VARIABLE OVER THE WEST AND
LESS FAVORABLE FOR LAKE EFFECT SNOW...BUT WILL MENTION SOME SNOW DUE
TO THE SYNOPTIC FORCING.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 458 AM EDT FRI MAR 15 2013
DURING THE LONG TERM...IT APPEARS BELOW NORMAL TEMPS WILL BE THE
RULE DUE TO HIGH LATITUDE BLOCKING/NEGATIVE NAO. THE MJO REMAINS
ACTIVE AS IT HAS FOR AT LEAST THE LAST 2 MONTHS. ITS FORECASTED
PHASE INITIALLY FAVORS WARMTH FOR THE ERN CONUS...BUT WILL TEND TO
FAVOR BELOW NORMAL TEMPS HEADING INTO THE END OF MAR. FOR THE TIME
BEING...THE HIGH LATITUDE BLOCKING WILL BE THE PRIMARY DRIVER...BUT
SHOULD THAT BREAK DOWN...THE MJO PHASE WILL BECOME MORE IMPORTANT.
IN THE END...THIS POINTS TO BELOW NORMAL TEMPS LIKELY BEING THE RULE
THRU THE END OF THE MONTH...EITHER BY HIGH LATITUDE BLOCKING OR MJO.
THE PATTERN SHOULD BE AN ACTIVE ONE...MAINLY DURING THE FIRST HALF
OR SO OF THIS LONG TERM PERIOD. FARTHER DOWN THE ROAD...LONG RANGE
GFS RUNS HAVE BEEN SUGGESTING THERE MAY CONTINUE TO BE AN ACTIVE
STORM TRACK ACROSS THE CONUS BEYOND THIS 7 DAY FCST. WITH EXPECTED
BELOW NORMAL TEMPS...MORE SNOW EVENTS MAY BE ON THE WAY AS WE HEAD
THRU LATE MAR.
BEGINNING SAT/SAT NIGHT...WITH HIGH LATITUDE POSITIVE HEIGHT
ANOMALIES OVER GREENLAND AND N OF ALASKA...A W-E ELONGATED POLAR
VORTEX WILL DOMINATE MUCH OF CANADA WITH CENTER OVER HUDSON BAY. IN
THE MORNING...A SHORTWAVE TROF WILL EXTEND FROM THE CENTER TO SRN
MANITOBA/SASKATCHEWAN. THIS WAVE WILL QUICKLY SWING THRU THE UPPER
LAKES SAT EVENING. WITH TRACK OF VORT MAX JUST N OF UPPER MI...
BETTER SNOW POTENTIAL WILL LIKELY PASS BY TO THE N. THAT SAID...
850MB TEMPS ACROSS LAKE SUPERIOR ARE PROGGED TO BE BTWN -16 AND
-20C...NORMALLY INDICATING THAT THERE WILL BE A PERIOD OF HVY LAKE
ENHANCED SNOW WITH COLD FROPA. IN THIS CASE...FCST SOUNDINGS SHOW A
WELL MIXED LAYER WHICH WILL BE A NEGATIVE. ON THE OTHER HAND...
VIGOROUS UPWARD MOTION IS FCST THRU A ROUGHLY 3KFT DGZ WITH
INVERSION BASE UP AROUND 8-9KFT. SO...STILL MAY END UP WITH A VERY
BRIEF PERIOD OF MDT/HVY SNOW WITH FROPA ACROSS THE N...ESPECIALLY
THE NW FCST AREA AND AREAS E OF MARQUETTE. EVEN INLAND MAY SEE SOME
RATHER VIGOROUS -SHSN FOR A BRIEF TIME GIVEN STEEP LOW-LEVEL LAPSE
RATES WITH UPWARD MOTION MAX INTERSECTING DGZ...THOUGH DRY AIR WILL
KEEP COVERAGE LOW. AFTER FROPA LATE SAT AFTN/EVENING...INVERSION
FALLS TO 4-5KFT SAT NIGHT. LOWERING INVERSION AND A CONTINUED
WELL-MIXED LAYER WILL WORK TO KEEP LES IN CHECK DESPITE 850MB TEMPS
FALLING TO AROUND -20C. DGZ DOES REMAIN FAVORABLY POSITIONED IN
CONVECTIVE LAYER...SO THERE SHOULD BE LIGHT ACCUMULATIONS OF FLUFFY
SNOW UNDER ADVY CRITERIA. GREATEST ACCUMULATIONS WILL BE OVER THE E
WHERE LONGER FETCH ACROSS LAKE SUPERIOR WILL WORK TO MOISTEN THE
LOW-LEVELS.
SUN...SFC HIGH PRES WILL SLIDE ACROSS THE UPPER LAKES. LINGERING
LES NEAR LAKE SUPERIOR WILL END...PROBABLY NO LATER THAN EARLY AFTN
AS COMBINATION OF NEGATIVE DYNAMICS/INCREASING ANTICYCLONIC
FLOW/DRYING/DAYTIME HEATING WITH INCREASING MARCH INSOLATION
DISRUPTS THE LES PROCESS. IN FACT...THE DAY IS LIKELY TO TURN MOSTLY
SUNNY IN THE AFTN W-E WITH WSHFT TO THE S FOLLOWING PASSAGE OF HIGH
PRES RDG AXIS. DESPITE INCREASING SUNSHINE...THE DAY WILLL FEATURE
BLO NORMAL MAX TEMPS MAINLY IN THE 20S WITH 850MB TEMPS RECOVERING
TO -12C TO -14C IN THE AFTN. QUIET WEATHER SHOULD LINGER THRU SUN
NIGHT.
FOR A FEW DAYS NOW...MEDIUM RANGE GUIDANCE HAS BEEN INDICATING THE
POTENTIAL FOR A WINTER STORM IN THE GREAT LAKES REGION MON/TUE.
SCENARIO IS FAR FROM CERTAIN DUE TO COMPLICATED PHASING ISSUES...
LEAVING TIMING AND LOCATION OF PHASING SYSTEM UNCERTAIN. MODELS HAVE
BEEN AND CONTINUE TO STRUGGLE WITH THE DETAILS. BASED ON TODAYS 00Z
AND YESTERDAYS 12Z RUNS...THE GENERAL THEME OF GUIDANCE IS FOR
PHASING TO OCCUR OVER THE GREAT LAKES...BUT PROBABLY A LITTLE TOO
FAR E TO BRING A WIDESPREAD HVY SNOW EVENT TO UPPER MI. HOWEVER...
GIVEN THE PHASING UNCERTAINTIES...MUCH COULD STILL CHANGE IN THE
NEXT FEW DAYS. CONFIDENCE IS A LITTLE HIGHER FOR HEAVIER SNOW NEAR
LAKE SUPERIOR AS LAKE ENHANCEMENT POTENTIAL LOOKS GOOD DUE TO
DEEPENING MIDLEVEL LOW OVER THE GREAT LAKES AND DEEP CYCLONIC FLOW
AFFECTING UPPER MI/LAKE SUPERIOR. LOW-LEVEL WIND DIRECTION IS AND
WILL CONTINUE TO BE THE IMPORTANT UNCERTAIN POINT...BUT AT THIS
TIME...GUIDANCE GENERALLY INDICATES MID LEVEL LOW CLOSING OFF N OR
NE OF THE AREA. THIS WOULD SUGGEST AREAS FAVORED BY NW WINDS WILL
SEE MAJORITY OF LAKE ENHANCEMENT. LIKELY POPS WILL CONTINUE TO
UTILIZED FOR THIS EVENT WITH PRIME SYNOPTIC SNOW PERIOD PROBABLY MON
AFTN/EVENING...AND THEN MAIN LAKE ENHANCEMENT PERIOD LATE MON NIGHT
THRU TUE.
BEHIND THE SYSTEM...LES WILL PROBABLY CONTINUE THRU WED UNDER
LINGERING MID LEVEL TROFFING WITH 850MB TEMPS AROUND -15C. THEN ON
THU...SYSTEM SHOULD BE FAR ENOUGH TO THE E TO ALLOW THE COMBINATION
OF RISING HEIGHTS/DRYING AND MARCH INSOLATION TO BRING AN END TO
MUCH OF THE LES.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 736 AM EDT FRI MAR 15 2013
COLD AIR DROPPING SOUTH ACROSS LAKE SUPERIOR WILL COMBINE WITH LOW
LEVEL MOISTURE TO LEAD TO MVFR CEILINGS AT ALL THREE SITES TODAY.
WITH THE AMOUNT OF COLD AIR...WOULDN/T EXPECT ANY SITES TO SCATTER
OUT EVEN WITH THE SHRINKING MOISTURE DEPTH. IF ANY LOCATION
SCATTERED OUT...WOULD EXPECT IT TO BE KIWD WITH THE UNFAVORABLE
NORTHEAST WINDS. OTHERWISE...TWO DISTURBANCES WILL BRUSH THE AREA
TODAY AND TONIGHT...WITH THE SECOND DISTURBANCE HAVING THE BETTER
CHANCE OF BRINGING -SHSN TO THE THREE SITES. KSAW WILL HAVE THE BEST
OPPORTUNITY FOR MODERATE SNOW WITH THE FAVORABLE NORTH-NORTHEAST
WINDS AND DEEP MOISTURE ARRIVING AFTER MIDNIGHT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 458 AM EDT FRI MAR 15 2013
AFTER A FEW GALE FORCE GUSTS TO 35KTS IMMEDIATELY BEHIND THE COLD
FRONT MOVING THROUGH EARLY THIS MORNING...WINDS WILL SLOWLY
DECREASE BELOW 25 KNOTS THIS AFTERNOON AND STAY OUT OF A NORTHERLY
DIRECTION INTO SATURDAY. ANOTHER TROUGH WILL CUT THROUGH THE HIGH
PRESSURE RIDGE AND SLIDE ACROSS LAKE SUPERIOR ON SATURDAY EVENING.
BEHIND THE TROUGH...THERE WILL BE A FEW GALE FORCE GUSTS TO 35KTS
OVER THE CENTRAL/EASTERN LAKE AND THERE IS ALSO THE POTENTIAL FOR
HEAVY FREEZING SPRAY. HIGH PRESSURE WILL THEN SETTLE BACK OVER THE
AREA FOR SUNDAY INTO SUNDAY NIGHT AND LEAD TO LIGHT WINDS. A LOW
PRESSURE SYSTEM EXITING THE NORTHERN PLAINS ON SUNDAY NIGHT WILL MOVE
INTO THE GREAT LAKES REGION FOR MONDAY NIGHT INTO TUESDAY. WINDS WILL
BE ON THE INCREASE AS THIS SYSTEM CROSSES THE REGION...WITH SOME
PERIODS OF WINDS UP TO 30KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...SRF
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
459 AM EDT FRI MAR 15 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 458 AM EDT FRI MAR 15 2013
COLD FRONT HAS JUST SLIDE THROUGH NORTH CENTRAL UPPER MICHIGAN
/WITH A QUICK WIND SHIFT TO THE NORTH/ AND WILL CONTINUE TO THE
SOUTH-SOUTHEAST AND EXIT UPPER MICHIGAN AROUND 12Z. WITH MUCH OF
THE DEEPER MOISTURE DEPARTING EARLIER IN THE EVENING...SNOW SHOWERS
HAVE QUICKLY DIMINISHED ACROSS THE AREA AND THERE HAVE EVEN BEEN
SOME BREAKS IN THE CLOUDS OVER THE NORTHEAST HALF OF LAKE SUPERIOR
BEHIND THE FRONT. BUT...AS COLDER AIR AS STARTED TO MOVE SOUTH
ACROSS THE LAKE /RAP ANALYZED 850MB TEMPS FALLING TO -13C/ THERE
HAVE BEEN LAKE EFFECT CLOUDS REDEVELOPING FROM NORTH TO SOUTH.
BEHIND THE TROUGH THAT HAS MOVED THROUGH THIS MORNING...HIGH
PRESSURE RIDGE FROM A PARENT HIGH OVER NORTHERN ALBERTA WILL MOVE
OVER LAKE SUPERIOR AND PROVIDE LIGHT NORTHERLY WINDS TO THE AREA.
THIS NORTHERLY FLOW...COMBINED WITH 875MB TEMPS AROUND -16C
WILL PROVIDE PLENTY OF OVER LAKE INSTABILITY AND COULD PRODUCE A FEW
LIGHT LAKE EFFECT/ENHANCED SNOW SHOWERS OVER THE NORTH CENTRAL CWA.
THERE ARE A COUPLE LIMITING FACTORS TO THE STRENGTH AND CHANCES.
FIRST...DRY AIR FROM 875-650MB WILL AID IN LOWERING THE INVERSION TO
3-3.5KFT TODAY. ALSO...WITH THE HIGH PRESSURE MOVING IN...FLOW WILL
BECOME ANTICYCLONIC/DIVERGENT THROUGH THE DAY. THEREFORE...THINK THE
BEST CHANCES WILL BE DURING THE FIRST PART OF THE MORNING HOURS AND
THEN DIMINISH FROM NORTH TO SOUTH AS THE DRIER AIR ARRIVES. DID
LEAVE THE MENTION OF FREEZING DRIZZLE IN OVER THE FAR WEST EARLY
THIS MORNING...DUE TO RAP SOUNDINGS SHOWING THE MORE MARGINAL ICE
PRESENCE THERE.
FARTHER SOUTH TODAY...THE FIRST OF TWO SHORTWAVES MOVING FROM THE
NORTHERN PLAINS TO THE LOWER GREAT LAKES WILL BRUSH THE CWA. AT
THIS TIME...WITH THE SURFACE TROUGH FROM THIS MORNING SLIDING WELL
SOUTH OF THE AREA AND THE WEST-NORTHWEST TO EAST-SOUTHEAST
ORIENTATED ISOTHERMS FROM 850-700MB SETUP FROM CENTRAL MINNESOTA TO
SOUTHEAST WISCONSIN...WOULD EXPECT THE BULK OF THE PRECIPITATION TO
ALIGN WITH THAT AREA. THEREFORE...HAVE CONTINUED THE REDUCTION TO
POPS AND HAVE DROPPED MENTION OF SNOW FROM AREAS NEAR THE WISCONSIN
BORDER EXCEPT FOR THE LAKE INFLUENCE NEAR IRONWOOD.
OVERALL...OTHER THAN A FEW BREAKS IN THE CLOUDS BEHIND THE
TROUGH...EXPECT A MAINLY CLOUDY DAY WITH THE COMBINED LAKE
INFLUENCE AND ADDITIONAL MID/HIGH CLOUDS FROM THE SYSTEM TO THE
SOUTH. WON/T BE MUCH REBOUND TO THE DAYBREAK TEMPERATURES OVER THE
NORTH AS THE COLDER AIR SURGES SOUTH ACROSS THE AREA BEHIND THE
COLD FRONT. THIS WILL LIKELY LEAD TO TEMPERATURES SLOWLY FALLING IN
THE AFTERNOON AND HAVE ADDED THAT TO THE FORECAST. ALL IN ALL...NOT
REALLY MARCH LIKE WEATHER FOR LOCATIONS NEAR LAKE SUPERIOR TODAY
WITH THE NORTHERLY WINDS OFF THE LAKE PRODUCING WIND CHILLS IN THE
SINGLE DIGITS FOR A GOOD PORTION OF THE DAY.
THEN FOR TONIGHT...THE SECOND SHORTWAVE WILL DROPS SOUTHEAST ALONG
A SIMILAR PATH...BUT THE LATEST TRENDS IN THE GLOBAL MODELS HAVE IT
BEING A TOUCH FARTHER TO THE NORTH. THAT BEING SAID...THE NAM SHOWS
IT TRACKING FARTHER SOUTH AND SIMILAR TO TODAY WAVE...WHICH CAUSES
SEVERAL OF THE HIGHER RESOLUTION RUNS THAT ARE BASED OFF THE NAM/S
INITIALIZATION TO FOLLOW SUIT. AGAIN...THE BEST THERMAL GRADIENT
WILL LIKELY BE TO THE SOUTH OF THE AREA...BUT WITH THE TRACK OF THE
SHORTWAVE AND DEEPER MOISTURE OVER THE AREA...FEEL COMFORTABLE
MENTIONING SCATTERED SNOW SHOWERS ALONG THE SOUTHWEST THIRD OF THE
CWA WITH THE HIGHEST AMOUNTS /NEAR AN INCH/ NEAR THE WISCONSIN
BORDER.
FARTHER TO THE NORTH...WITH THE INCREASING MOISTURE AND H850 TEMPS
AROUND -18C...THERE IS AMPLE LAKE INDUCED INSTABILITY FOR LAKE
EFFECT SNOW SHOWERS. HAVE TRENDED POPS UP FOR THE NORTH
CENTRAL...ESPECIALLY AFTER 06Z WHEN 1000-850MB LAPSE RATES APPROACH
8C/KM AND THERE IS SOME INCREASED CONVERGENCE IN THE LOW LEVEL
FLOW. WOULDN/T EXPECT SNOW AMOUNTS TO GET TOO OUT OF CONTROL...DUE
TO SHEAR FROM WINDS ABOVE 850MB BEING OUT OF THE WNW AND THE LOW
LEVELS OUT OF THE NNE. BUT WITH MUCH OF THE CLOUD LAYER WITHIN THE
DGZ...COULD SEE A FLUFFY INCH OR MAYBE TWO OVER THE HIGHER TERRAIN
OF MARQUETTE OR BARAGA COUNTY /HURON MOUNTAINS/. THERE ARE A FEW
HIGHER RESOLUTION MODELS THAT ARE SHOWING AMOUNTS TOWARDS 3
INCHES...SO IT WILL BE SOMETHING TO WATCH FOR FUTURE SHIFTS.
ELSEWHERE...WIND FIELD IS MORE VARIABLE OVER THE WEST AND
LESS FAVORABLE FOR LAKE EFFECT SNOW...BUT WILL MENTION SOME SNOW DUE
TO THE SYNOPTIC FORCING.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 458 AM EDT FRI MAR 15 2013
DURING THE LONG TERM...IT APPEARS BELOW NORMAL TEMPS WILL BE THE
RULE DUE TO HIGH LATITUDE BLOCKING/NEGATIVE NAO. THE MJO REMAINS
ACTIVE AS IT HAS FOR AT LEAST THE LAST 2 MONTHS. ITS FORECASTED
PHASE INITIALLY FAVORS WARMTH FOR THE ERN CONUS...BUT WILL TEND TO
FAVOR BELOW NORMAL TEMPS HEADING INTO THE END OF MAR. FOR THE TIME
BEING...THE HIGH LATITUDE BLOCKING WILL BE THE PRIMARY DRIVER...BUT
SHOULD THAT BREAK DOWN...THE MJO PHASE WILL BECOME MORE IMPORTANT.
IN THE END...THIS POINTS TO BELOW NORMAL TEMPS LIKELY BEING THE RULE
THRU THE END OF THE MONTH...EITHER BY HIGH LATITUDE BLOCKING OR MJO.
THE PATTERN SHOULD BE AN ACTIVE ONE...MAINLY DURING THE FIRST HALF
OR SO OF THIS LONG TERM PERIOD. FARTHER DOWN THE ROAD...LONG RANGE
GFS RUNS HAVE BEEN SUGGESTING THERE MAY CONTINUE TO BE AN ACTIVE
STORM TRACK ACROSS THE CONUS BEYOND THIS 7 DAY FCST. WITH EXPECTED
BELOW NORMAL TEMPS...MORE SNOW EVENTS MAY BE ON THE WAY AS WE HEAD
THRU LATE MAR.
BEGINNING SAT/SAT NIGHT...WITH HIGH LATITUDE POSITIVE HEIGHT
ANOMALIES OVER GREENLAND AND N OF ALASKA...A W-E ELONGATED POLAR
VORTEX WILL DOMINATE MUCH OF CANADA WITH CENTER OVER HUDSON BAY. IN
THE MORNING...A SHORTWAVE TROF WILL EXTEND FROM THE CENTER TO SRN
MANITOBA/SASKATCHEWAN. THIS WAVE WILL QUICKLY SWING THRU THE UPPER
LAKES SAT EVENING. WITH TRACK OF VORT MAX JUST N OF UPPER MI...
BETTER SNOW POTENTIAL WILL LIKELY PASS BY TO THE N. THAT SAID...
850MB TEMPS ACROSS LAKE SUPERIOR ARE PROGGED TO BE BTWN -16 AND
-20C...NORMALLY INDICATING THAT THERE WILL BE A PERIOD OF HVY LAKE
ENHANCED SNOW WITH COLD FROPA. IN THIS CASE...FCST SOUNDINGS SHOW A
WELL MIXED LAYER WHICH WILL BE A NEGATIVE. ON THE OTHER HAND...
VIGOROUS UPWARD MOTION IS FCST THRU A ROUGHLY 3KFT DGZ WITH
INVERSION BASE UP AROUND 8-9KFT. SO...STILL MAY END UP WITH A VERY
BRIEF PERIOD OF MDT/HVY SNOW WITH FROPA ACROSS THE N...ESPECIALLY
THE NW FCST AREA AND AREAS E OF MARQUETTE. EVEN INLAND MAY SEE SOME
RATHER VIGOROUS -SHSN FOR A BRIEF TIME GIVEN STEEP LOW-LEVEL LAPSE
RATES WITH UPWARD MOTION MAX INTERSECTING DGZ...THOUGH DRY AIR WILL
KEEP COVERAGE LOW. AFTER FROPA LATE SAT AFTN/EVENING...INVERSION
FALLS TO 4-5KFT SAT NIGHT. LOWERING INVERSION AND A CONTINUED
WELL-MIXED LAYER WILL WORK TO KEEP LES IN CHECK DESPITE 850MB TEMPS
FALLING TO AROUND -20C. DGZ DOES REMAIN FAVORABLY POSITIONED IN
CONVECTIVE LAYER...SO THERE SHOULD BE LIGHT ACCUMULATIONS OF FLUFFY
SNOW UNDER ADVY CRITERIA. GREATEST ACCUMULATIONS WILL BE OVER THE E
WHERE LONGER FETCH ACROSS LAKE SUPERIOR WILL WORK TO MOISTEN THE
LOW-LEVELS.
SUN...SFC HIGH PRES WILL SLIDE ACROSS THE UPPER LAKES. LINGERING
LES NEAR LAKE SUPERIOR WILL END...PROBABLY NO LATER THAN EARLY AFTN
AS COMBINATION OF NEGATIVE DYNAMICS/INCREASING ANTICYCLONIC
FLOW/DRYING/DAYTIME HEATING WITH INCREASING MARCH INSOLATION
DISRUPTS THE LES PROCESS. IN FACT...THE DAY IS LIKELY TO TURN MOSTLY
SUNNY IN THE AFTN W-E WITH WSHFT TO THE S FOLLOWING PASSAGE OF HIGH
PRES RDG AXIS. DESPITE INCREASING SUNSHINE...THE DAY WILLL FEATURE
BLO NORMAL MAX TEMPS MAINLY IN THE 20S WITH 850MB TEMPS RECOVERING
TO -12C TO -14C IN THE AFTN. QUIET WEATHER SHOULD LINGER THRU SUN
NIGHT.
FOR A FEW DAYS NOW...MEDIUM RANGE GUIDANCE HAS BEEN INDICATING THE
POTENTIAL FOR A WINTER STORM IN THE GREAT LAKES REGION MON/TUE.
SCENARIO IS FAR FROM CERTAIN DUE TO COMPLICATED PHASING ISSUES...
LEAVING TIMING AND LOCATION OF PHASING SYSTEM UNCERTAIN. MODELS HAVE
BEEN AND CONTINUE TO STRUGGLE WITH THE DETAILS. BASED ON TODAYS 00Z
AND YESTERDAYS 12Z RUNS...THE GENERAL THEME OF GUIDANCE IS FOR
PHASING TO OCCUR OVER THE GREAT LAKES...BUT PROBABLY A LITTLE TOO
FAR E TO BRING A WIDESPREAD HVY SNOW EVENT TO UPPER MI. HOWEVER...
GIVEN THE PHASING UNCERTAINTIES...MUCH COULD STILL CHANGE IN THE
NEXT FEW DAYS. CONFIDENCE IS A LITTLE HIGHER FOR HEAVIER SNOW NEAR
LAKE SUPERIOR AS LAKE ENHANCEMENT POTENTIAL LOOKS GOOD DUE TO
DEEPENING MIDLEVEL LOW OVER THE GREAT LAKES AND DEEP CYCLONIC FLOW
AFFECTING UPPER MI/LAKE SUPERIOR. LOW-LEVEL WIND DIRECTION IS AND
WILL CONTINUE TO BE THE IMPORTANT UNCERTAIN POINT...BUT AT THIS
TIME...GUIDANCE GENERALLY INDICATES MID LEVEL LOW CLOSING OFF N OR
NE OF THE AREA. THIS WOULD SUGGEST AREAS FAVORED BY NW WINDS WILL
SEE MAJORITY OF LAKE ENHANCEMENT. LIKELY POPS WILL CONTINUE TO
UTILIZED FOR THIS EVENT WITH PRIME SYNOPTIC SNOW PERIOD PROBABLY MON
AFTN/EVENING...AND THEN MAIN LAKE ENHANCEMENT PERIOD LATE MON NIGHT
THRU TUE.
BEHIND THE SYSTEM...LES WILL PROBABLY CONTINUE THRU WED UNDER
LINGERING MID LEVEL TROFFING WITH 850MB TEMPS AROUND -15C. THEN ON
THU...SYSTEM SHOULD BE FAR ENOUGH TO THE E TO ALLOW THE COMBINATION
OF RISING HEIGHTS/DRYING AND MARCH INSOLATION TO BRING AN END TO
MUCH OF THE LES.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 747 PM EDT THU MAR 14 2013
AS A COLD FRONT APPROACHES FROM NORTHWEST MINNESOTA THIS
EVENING...EXPECT CONDITIONS TO FALL TO MVFR AND PRODUCE SNOW SHOWERS
FOR KCMX/KSAW. BEHIND THE FRONT...WINDS WILL TURN
NORTH-NORTHWESTERLY AND LEAD TO LIGHT UPSLOPE AND LAKE ENHANCED
SNOW. MVFR CONDITIONS SHOULD LINGER THROUGH FRIDAY WITH LAKE
CLOUDS/FLURRIES AS COLD AIR MOVES IN ON NNE WINDS ACROSS LAKE
SUPERIOR.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 458 AM EDT FRI MAR 15 2013
AFTER A FEW GALE FORCE GUSTS TO 35KTS IMMEDIATELY BEHIND THE COLD
FRONT MOVING THROUGH EARLY THIS MORNING...WINDS WILL SLOWLY
DECREASE BELOW 25 KNOTS THIS AFTERNOON AND STAY OUT OF A NORTHERLY
DIRECTION INTO SATURDAY. ANOTHER TROUGH WILL CUT THROUGH THE HIGH
PRESSURE RIDGE AND SLIDE ACROSS LAKE SUPERIOR ON SATURDAY EVENING.
BEHIND THE TROUGH...THERE WILL BE A FEW GALE FORCE GUSTS TO 35KTS
OVER THE CENTRAL/EASTERN LAKE AND THERE IS ALSO THE POTENTIAL FOR
HEAVY FREEZING SPRAY. HIGH PRESSURE WILL THEN SETTLE BACK OVER THE
AREA FOR SUNDAY INTO SUNDAY NIGHT AND LEAD TO LIGHT WINDS. A LOW
PRESSURE SYSTEM EXITING THE NORTHERN PLAINS ON SUNDAY NIGHT WILL MOVE
INTO THE GREAT LAKES REGION FOR MONDAY NIGHT INTO TUESDAY. WINDS WILL
BE ON THE INCREASE AS THIS SYSTEM CROSSES THE REGION...WITH SOME
PERIODS OF WINDS UP TO 30KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...JLB
MARINE...SRF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1228 PM CDT FRI MAR 15 2013
.PREV DISCUSSION.../ISSUED AT 444 AM CDT FRI MAR 15 2013/
CERTAINLY WHEN ONE READS THROUGH THE FORECAST FOR THE NEXT
WEEK...THE LAST WORD THAT YOU WOULD ASSOCIATE WITH THIS WEATHER IS
SPRING! HAVE TWO SYSTEMS TO DEAL WITH THIS PERIOD. THE FIRST WILL
COME FROM TWO WAVES SPREAD OUT OVER TODAY AND TONIGHT. FIRST WAVE
THIS MORNING WILL POSE P-TYPE ISSUES...WITH ROUND TWO BRINGING
ANOTHER ROUND OF SNOW FROM LATE THIS AFTERNOON INTO TONIGHT. OTHER
SYSTEM WILL BE A POTENT LOW FOR SUNDAY NIGHT THROUGH MONDAY. AS
FOR TEMPERATURES...THOUGH NORMAL HIGHS ARE NOW RAPIDLY CLIMBING
THROUGH THE 40S...HIGHS THIS WEEKEND INTO NEXT WEEK LOOK TO BE
HEADING BACK INTO THE TEENS AND 20S...WELCOME TO SPRING MN/WI
STYLE!
INTERESTING WEATHER PATTERN UNFOLDING THIS MORNING. RAP H5 ANALYSIS
SHOWS THE POLAR VORTEX MAKING A RETURN TO WRN HUDSON BAY
/WHERE CHURCHILL H5 TEMP LAST NIGHT WAS -45C/ AS A SOMEWHAT FLAT
UPPER RIDGE CENTERED ALONG THE FOOTHILLS OF THE ROCKIES HAS A
RATHER PERTURBED NW FLOW ACROSS THE NRN PLAINS/UPPER MIDWEST. THE
POLAR VORTEX HAS BEEN SENDING ARCTIC AIR BACK SOUTH ACROSS THE
CANADIAN PRAIRIES INTO THIS WARM RIDGE AND AS IT HAS DONE
SO...HAVE REALLY SEEN THERMAL GRADIENTS FROM 925 MB UP THROUGH 500
MB TIGHTEN UP. THIS TIGHTENING OF THE THERMAL GRADIENT HAS INDUCED
STRONG FGEN ALOFT...WITH PRECIP STARTING TO RAPIDLY BREAK OUT FROM
WEST CENTRAL MN BACK THROUGH CENTRAL NODAK. THIS STRONG TEMP
GRADIENT AND FGEN RIBBON WILL REMAIN IN PLACE ACROSS THE REGION
THROUGH TONIGHT AND WILL SERVE AS A FOCUS FOR TWO WAVES OF
PRECIPITATION.
FIRST WAVE OF PRECIP THIS MORNING HAS BEEN REALLY STRUGGLING WITH
DRY AIR AS EVIDENCED BY 00Z SOUNDINGS FROM BIS/ABR/MPX. MODELS HAVE
BEEN A BIT TOO AGGRESSIVE IN BREAKING OUT PRECIP AND CERTAINLY
CURRENT GRIDS MAY BE A LITTLE AGGRESSIVE WITH ERN EXTENT OF PRECIP
RIGHT OUT THE GATES AT 12Z. OF COURSE BESIDE THE DRY AIR...OTHER
ISSUE WITH THE 00Z SOUNDING FOR MPX WAS THE WARM NOSE CENTERED AT
860 MB OF +6C. FORECAST SOUNDING FROM THE RAP/NAM SHOW THAT THIS
ABOVE ZERO WARM NOSE IS STILL MOSTLY IN PLACE THIS MORNING...WITH
THE THREAT FOR FREEZING RAIN CERTAINLY THERE. THOUGH THE
TEMPERATURE IN THE WARM NOSE IS WELL ABOVE FREEZING...WITH DRY AIR
IN PLACE...BOTH THE RAP AND NAM SHOW THE VERTICAL PROFILE OF THE
WET BULB TEMPERATURE IS MORE OR LESS NEAR OR BELOW ZERO FOR MOST
AREAS NORTHEAST OF THE UPPER MN RIVER. AS ATMO MOISTENS FROM TOP
DOWN...EVAP COOLING SHOULD QUICKLY BEAT BACK THIS WARM NOSE...WITH
PRECIP STARTING OUT AS A COUPLE OF HOURS OF FZRA/SN BEFORE GOING
ALL SNOW. BASED ON A RAP/NAM/GEM BLEND EXPECT THIS FIRST ROUND OF
PRECIP TO MAINLY FALL ALONG AND NORTHEAST OF THE MN RIVER...AND BE
BASICALLY CENTERED ON THE I-94 CORRIDOR. SNOW TOTALS ARE A TOUGH
CALL WITH THIS WAVE...AS INITIAL FZRA WILL TAKE A BITE OUT OF SNOW
TOTALS...BUT GENERALLY EXPECT 1-3 INCHES WITH THIS.
EXPECT ABOUT A 4 HOUR LULL BETWEEN FIRST AND SECOND ROUND OF SNOW
AND TRIED TIMING THIS LULL ACROSS THE AREA ON A NAM/GEM TIMING.
WITH THE SAME NAM/GEM BLEND...EXPECT ROUND TWO TO MOVE INTO THE NW
CWA AROUND 20Z AND PUSH BACK INTO WRN WI AROUND 00Z.
FORTUNATELY...BY THE TIME THIS SECOND PUSH OF PRECIP ARRIVES...
CONTINUOUS CAA THROUGH THE DAY WILL MAKE THIS AN ALL SNOW
FEATURE. MODELS SHOW THIS FEATURE TRACKING SLIGHTLY FARTHER SOUTH
OF THE FIRST ONE...BUT AGAIN...PRECIP CHANCES LOOK BEST ALONG
NORTH OF GRANITE FALLS/MANKATO/LA CROSSE LINE. SINCE THIS WAVE
WILL BE ALL SNOW...WILL HAVE TO POTENTIAL TO PRODUCE SLIGHT HIGHER
ACCUMS IN THE 2-4 INCH RANGE. WITH THIS FORECAST PACKAGE...HAVE
BASICALLY 2-4 INCHES OF STORM TOTAL SNOW NE OF A
MORRIS/LITCHFIELD/NORTHFIELD LINE. BASED ON THESE CHANGES...SRN ROWS
OF COUNTIES IN ADVY MAY BE QUESTIONABLE...BUT WITH MODELS SUCH AS
THE GFS/HIRES-ARW SHOWING SNOW OCCURRING A BIT FARTHER SOUTH
TONIGHT...IMPACTING THE SRN END OF THE ADVY...DECIDED THERE IS
ENOUGH UNCERTAINTY WITH WHERE THE SECOND WAVE GOES TO KEEP THE
ADVY UNCHANGED.
BEHIND THIS SYSTEM...ARCTIC HIGH SHOWS UP FOR THE WEEKEND. THIS
WILL DRY THINGS OUT FOR ST. PATRICK`S DAY WEEKEND...BUT WILL HAVE
TO WATCH LOWS FOR SUNDAY MORNING. CLOUDS LOOK TO HOLD TIGHT
THROUGH SATURDAY...BUT SATURDAY NIGHT SKIES LOOK TO CLEAR OUT AS A
1028 MB HIGH MOVES OVER NE MN. THIS COULD SET THE STAGE FOR MORE
BELOW ZERO LOWS...ESPECIALLY ACROSS CENTRAL MN. IN FACT...FOR
SUNDAY MORNING...6 OF THE 21 SREF MEMBERS HAVE A LOW OF -10 F OR
COLDER AT ST. CLOUD. BASED ON THIS COLD SIGNAL...DID KNOCK A FEW
DEGREES OFF OF ALL-BLEND LOWS FOR SUNDAY MORNING. ONLY OTHER CHANGE
MADE FOR SUNDAY WAS TO REMOVE POPS FROM SUNDAY AFTERNOON..AS
PRECIP FROM THE NEXT SYSTEM LOOKS TO ARRIVE IN ERNEST SUNDAY
NIGHT.
AS FOR THAT SUNDAY NIGHT/MONDAY SYSTEM...GFS/ECMWF/GEM CONTINUE
TO SHOW A NEGATIVELY TILTED UPPER WAVE MOVING ACROSS MN/WI MONDAY.
WHAT IS LEADING TO SOME UNCERTAINTY THOUGH WITH THE MODELS IS A
LEAD SRN STREAM SHORTWAVE THAT WILL BE MOVING ACROSS MO ON SUNDAY
AND BE HEADING FOR MICH ON MONDAY. THESE TWO FEATURE WILL PHASE
WITH EACH OTHER AT SOME POINT. ECMWF PHASES THESE SYSTEM MONDAY
AFTERNOON...WHILE THE GFS/GEM ARE ABOUT 12 HOURS BEHIND. WHEN THE
PHASING OCCURS..THIS SFC LOW LOOKS TO DEEPEN BY SEVERAL MB...BUT
THIS DEEPENING LOOKS TO MAINLY HAPPEN TO THE EAST. WHAT THIS WILL
DO THOUGH IS RESULT IN THE DEVELOPMENT IN VERY STRONG WINDS BY
MONDAY AFTERNOON ACROSS WRN AREAS...WITH SUSTAINED WINDS LIKELY
BETWEEN 20 AND 30 MPH...WITH GUSTS POSSIBLY TOPPING 40 MPH. AS FOR
SNOWFALL AMOUNTS...SFC LOW FROM THE ECMWF/GFS LOOKS TO TRACK
ACROSS FROM MORRIS...TO THE NRN TWIN CITIES...TO LADYSMITH WITH
THE MAIN PV ANOMALY GOING ACROSS SRN MN. THIS ALL POINTS TO
CENTRAL MN HAVING THE HIGHEST POTENTIAL FOR SEEING SIGNIFICANT
SNOWS. WITH THE 15.00 RUNS...THE GFS IS GENERALLY PRODUCING 6-9
INCHES OF SNOW...WITH THE ECMWF MORE 4-7. EVEN IF 6 INCH SNOWS ARE
NOT WIDESPREAD...EXPECTED STRONG WINDS MONDAY/MONDAY NIGHT WILL
LIKELY FORCE THE NEED FOR HEADLINES OF SOME VARIETY IN THE FUTURE.
BEHIND THIS SYSTEM BOTH THE GFS/ECMWF SHOW A STRONG REX BLOCK
SETTING UP ACROSS ERN NOAM...WHICH CAUSES AN ARCTIC HIGH WITH SFC
PRESSURES FROM 1030 TO 1040 MB TO MORE OR LESS STAY PARKED OVER
THE CENTER OF THE CONTINENT FOR MUCH OF NEXT WEEK. H85 TEMPS OFF
THE GFS/ECMWF AROUND -10C MUCH OF NEXT WEEK...AND WITH A SFC RIDGE
MORE OR LESS OVERHEAD...DEPENDING ON CLOUD COVER...TUESDAY THROUGH
THURSDAY MORNINGS COULD VERY WILL BRING THREE MORE OPPORTUNITIES
TO SEE BELOW ZERO LOWS. IN ADDITION TO THE WINTER LIKE
LOWS...HIGHS NEXT WEEK WILL BE RUNNING 15 TO 25 DEGS BELOW NORMAL.
IN FACT EVEN LOOKING AT THE CFS...THERE DOES NOT LOOK TO BE ANY
SIGNIFICANT WARM UPS IN SITE POSSIBLY THOUGH THE REST OF THIS
MONTH.
&&
.AVIATION.../18Z TAF ISSUANCE/
FIRST WAVE OF PRECIPITATION HAS MOVED OFF TO THE SE OF MPX TAF
SITES. NEXT BAND OF SNOW HAS ALREADY DEVELOPED ACROSS CENTRAL
ND...AND MOVING TOWARD THE ESE...BRINGING THE NEXT ROUND AT AXN
NEAR 21Z.
MAIN AVIATION CONCERN IS TIMING AND INTENSITY OF NEXT WAVE...AND
WHETHER THERE WILL REMAIN A MIX OF -FZRA/FZDZ/SN IN THE SW FA.
BASED ON THE LATEST REGIONAL RADAR AND OBSERVATIONS UPSTREAM
ACROSS ND...SNOWFALL RATES WILL BEGIN TO INCREASE ONCE THE NEXT
WAVE OF PRECIPITATION DEVELOPS ACROSS MPX FA. THE LATEST DISTANCE
SPEED TOOL HAS THE INITIAL WAVE MOVING INTO AXN ARND 20-21Z...WITH
LIGHT TO MODERATE SNOWFALL LIKELY FOR A 3 TO 4 HR TIME FRAME. THIS
WILL TRANSLATE SE TOWARD STC BY 22-23Z AND AT MSP/RNH AFT 23Z. EAU
WILL LIKELY HOLD OFF UNTIL AFT 01Z. FURTHER TO THE SW...LATEST
RAP/HOPWRF MODEL TRENDS INDICATED THAT THE PRECIPITATION TYPE WILL
REMAIN MIXED ACROSS RWF FOR THE MAIN PRECIPITATION EVENT THIS
AFTN. THICKNESS VALUES AND THE ORIENTATION OF THE 85H WINDS
CONTINUES A WARM LAYER TOWARD 00Z...WITH THE TRANSITION OF -SN AFT
00Z/16. AT THIS TIME...MOST OF THE PRECIPITATION WOULD END IN THE
SW BY 00-02Z/16. ELSEWHERE...THICKNESS VALUES SHOULD REMAIN LOW
ENOUGH FOR ALL SNOW...BUT MSP COULD BE ON THE EDGE. LATER SHIFTS
WILL NEED TO EVALUATE THE WARMER LAYER THIS AFTN/EVENING. THE
PRECIPITATION WILL END BY 6Z...WITH MAINLY FLURRIES AFT THIS TIME
FRAME. IFR CIGS/VSBYS WILL LIKELY OCCUR DURING THE
PRECIPITATION...WITH IFR CIGS AND MVFR VSBYS ONCE THE
PRECIPITATION STOPS. VFR CONDS ARE POSSIBLE AT AXN/STC BY THE END
OF THE TAF PERIOD. WINDS WILL CONTINUE FROM THE NE ARND 10 KTS
THIS AFTN...BECOMING NNE THIS EVENING...THEN NNW/NW BY SATURDAY
MORNING. SPDS WILL REMAIN ARND 10-12 KTS.
KMSP...
TIMING OF THE NEXT WAVE OF PRECIPITATION LOOKS TO BE AROUND
23-00Z. WITH A PERIOD OF IFR CIGS/VSBYS IN SNOW THRU 3Z. THERE IS
SOME CONCERN THAT BEFORE 00Z/16...SOME OF THE PRECIPITATION MAY BE
IN THE FORM OF SLEET AS THICKNESS VALUES ARE CRITICAL JUST SOUTH
OF THE AIRPORT TERMINAL. ANY DEVIATION OF THE COLDER OR WARMER AIR
ALOFT WILL CHG THE PRECIPITATION TYPE. HOWEVER...AFT
00Z/16...CONFIDENCE IN ALL SNOW IS HIGH. EXPECT A DECREASE IN THE
INTENSIFY AFT 3Z...WITH MAINLY FLURRIES OVERNIGHT. CIGS WILL
SLOWLY LIFT SATURDAY MORNING...WITH MVFR CIGS /ABV 1.7K/ LIKELY
AFT 18Z. WINDS WILL BE GENERALLY FROM THE NE THIS AFTN ARND 10
KTS...WITH A TURN TO THE NNE/N THIS EVENING...AND MORE NNW/NW
SATURDAY MORNING AND REMAINING ARND 8-12 KTS.
/OUTLOOK FOR KMSP/
SUN...VFR EARLY WITH MVFR/IFR AND -SN LATE. WINDS E AT 5-10KT.
BECOMING SE AT 10-15KTS
MON...MVFR/IFR CIGS/VSBYS WITH SN. WINDS SE AT 10-15KTS BECOMING
WNW AT 20G30KTS LATE.
TUE...-SN EARLY WITH MVFR...BECOMING VFR. W/WNW WINDS 10 KTS.
..JLT..
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL 1 AM CDT SATURDAY FOR ANOKA-BENTON-
BLUE EARTH-BROWN-CARVER-CHIPPEWA-CHISAGO-DAKOTA-DOUGLAS-
GOODHUE-HENNEPIN-ISANTI-KANABEC-KANDIYOHI-LAC QUI PARLE-LE
SUEUR-MCLEOD-MEEKER-MILLE LACS-MORRISON-NICOLLET-POPE-
RAMSEY-REDWOOD-RENVILLE-RICE-SCOTT-SHERBURNE-SIBLEY-STEARNS-
STEELE-STEVENS-SWIFT-TODD-WASECA-WASHINGTON-WRIGHT-YELLOW
MEDICINE.
WI...WINTER WEATHER ADVISORY UNTIL 1 AM CDT SATURDAY FOR BARRON-
CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX.
&&
$$
MPG/JLT
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
704 AM CDT FRI MAR 15 2013
.UPDATE...
UPDATED FOR 12Z AVIATION DISCUSSION BELOW.
&&
.PREV DISCUSSION.../ISSUED AT 444 AM CDT FRI MAR 15 2013/
CERTAINLY WHEN ONE READS THROUGH THE FORECAST FOR THE NEXT
WEEK...THE LAST WORD THAT YOU WOULD ASSOCIATE WITH THIS WEATHER IS
SPRING! HAVE TWO SYSTEMS TO DEAL WITH THIS PERIOD. THE FIRST WILL
COME FROM TWO WAVES SPREAD OUT OVER TODAY AND TONIGHT. FIRST WAVE
THIS MORNING WILL POSE P-TYPE ISSUES...WITH ROUND TWO BRINGING
ANOTHER ROUND OF SNOW FROM LATE THIS AFTERNOON INTO TONIGHT. OTHER
SYSTEM WILL BE A POTENT LOW FOR SUNDAY NIGHT THROUGH MONDAY. AS
FOR TEMPERATURES...THOUGH NORMAL HIGHS ARE NOW RAPIDLY CLIMBING
THROUGH THE 40S...HIGHS THIS WEEKEND INTO NEXT WEEK LOOK TO BE
HEADING BACK INTO THE TEENS AND 20S...WELCOME TO SPRING MN/WI
STYLE!
INTERESTING WEATHER PATTERN UNFOLDING THIS MORNING. RAP H5 ANALYSIS
SHOWS THE POLAR VORTEX MAKING A RETURN TO WRN HUDSON BAY
/WHERE CHURCHILL H5 TEMP LAST NIGHT WAS -45C/ AS A SOMEWHAT FLAT
UPPER RIDGE CENTERED ALONG THE FOOTHILLS OF THE ROCKIES HAS A
RATHER PERTURBED NW FLOW ACROSS THE NRN PLAINS/UPPER MIDWEST. THE
POLAR VORTEX HAS BEEN SENDING ARCTIC AIR BACK SOUTH ACROSS THE
CANADIAN PRAIRIES INTO THIS WARM RIDGE AND AS IT HAS DONE
SO...HAVE REALLY SEEN THERMAL GRADIENTS FROM 925 MB UP THROUGH 500
MB TIGHTEN UP. THIS TIGHTENING OF THE THERMAL GRADIENT HAS INDUCED
STRONG FGEN ALOFT...WITH PRECIP STARTING TO RAPIDLY BREAK OUT FROM
WEST CENTRAL MN BACK THROUGH CENTRAL NODAK. THIS STRONG TEMP
GRADIENT AND FGEN RIBBON WILL REMAIN IN PLACE ACROSS THE REGION
THROUGH TONIGHT AND WILL SERVE AS A FOCUS FOR TWO WAVES OF
PRECIPITATION.
FIRST WAVE OF PRECIP THIS MORNING HAS BEEN REALLY STRUGGLING WITH
DRY AIR AS EVIDENCED BY 00Z SOUNDINGS FROM BIS/ABR/MPX. MODELS HAVE
BEEN A BIT TOO AGGRESSIVE IN BREAKING OUT PRECIP AND CERTAINLY
CURRENT GRIDS MAY BE A LITTLE AGGRESSIVE WITH ERN EXTENT OF PRECIP
RIGHT OUT THE GATES AT 12Z. OF COURSE BESIDE THE DRY AIR...OTHER
ISSUE WITH THE 00Z SOUNDING FOR MPX WAS THE WARM NOSE CENTERED AT
860 MB OF +6C. FORECAST SOUNDING FROM THE RAP/NAM SHOW THAT THIS
ABOVE ZERO WARM NOSE IS STILL MOSTLY IN PLACE THIS MORNING...WITH
THE THREAT FOR FREEZING RAIN CERTAINLY THERE. THOUGH THE
TEMPERATURE IN THE WARM NOSE IS WELL ABOVE FREEZING...WITH DRY AIR
IN PLACE...BOTH THE RAP AND NAM SHOW THE VERTICAL PROFILE OF THE
WET BULB TEMPERATURE IS MORE OR LESS NEAR OR BELOW ZERO FOR MOST
AREAS NORTHEAST OF THE UPPER MN RIVER. AS ATMO MOISTENS FROM TOP
DOWN...EVAP COOLING SHOULD QUICKLY BEAT BACK THIS WARM NOSE...WITH
PRECIP STARTING OUT AS A COUPLE OF HOURS OF FZRA/SN BEFORE GOING
ALL SNOW. BASED ON A RAP/NAM/GEM BLEND EXPECT THIS FIRST ROUND OF
PRECIP TO MAINLY FALL ALONG AND NORTHEAST OF THE MN RIVER...AND BE
BASICALLY CENTERED ON THE I-94 CORRIDOR. SNOW TOTALS ARE A TOUGH
CALL WITH THIS WAVE...AS INITIAL FZRA WILL TAKE A BITE OUT OF SNOW
TOTALS...BUT GENERALLY EXPECT 1-3 INCHES WITH THIS.
EXPECT ABOUT A 4 HOUR LULL BETWEEN FIRST AND SECOND ROUND OF SNOW
AND TRIED TIMING THIS LULL ACROSS THE AREA ON A NAM/GEM TIMING.
WITH THE SAME NAM/GEM BLEND...EXPECT ROUND TWO TO MOVE INTO THE NW
CWA AROUND 20Z AND PUSH BACK INTO WRN WI AROUND 00Z.
FORTUNATELY...BY THE TIME THIS SECOND PUSH OF PRECIP ARRIVES...
CONTINUOUS CAA THROUGH THE DAY WILL MAKE THIS AN ALL SNOW
FEATURE. MODELS SHOW THIS FEATURE TRACKING SLIGHTLY FARTHER SOUTH
OF THE FIRST ONE...BUT AGAIN...PRECIP CHANCES LOOK BEST ALONG
NORTH OF GRANITE FALLS/MANKATO/LA CROSSE LINE. SINCE THIS WAVE
WILL BE ALL SNOW...WILL HAVE TO POTENTIAL TO PRODUCE SLIGHT HIGHER
ACCUMS IN THE 2-4 INCH RANGE. WITH THIS FORECAST PACKAGE...HAVE
BASICALLY 2-4 INCHES OF STORM TOTAL SNOW NE OF A
MORRIS/LITCHFIELD/NORTHFIELD LINE. BASED ON THESE CHANGES...SRN ROWS
OF COUNTIES IN ADVY MAY BE QUESTIONABLE...BUT WITH MODELS SUCH AS
THE GFS/HIRES-ARW SHOWING SNOW OCCURRING A BIT FARTHER SOUTH
TONIGHT...IMPACTING THE SRN END OF THE ADVY...DECIDED THERE IS
ENOUGH UNCERTAINTY WITH WHERE THE SECOND WAVE GOES TO KEEP THE
ADVY UNCHANGED.
BEHIND THIS SYSTEM...ARCTIC HIGH SHOWS UP FOR THE WEEKEND. THIS
WILL DRY THINGS OUT FOR ST. PATRICK`S DAY WEEKEND...BUT WILL HAVE
TO WATCH LOWS FOR SUNDAY MORNING. CLOUDS LOOK TO HOLD TIGHT
THROUGH SATURDAY...BUT SATURDAY NIGHT SKIES LOOK TO CLEAR OUT AS A
1028 MB HIGH MOVES OVER NE MN. THIS COULD SET THE STAGE FOR MORE
BELOW ZERO LOWS...ESPECIALLY ACROSS CENTRAL MN. IN FACT...FOR
SUNDAY MORNING...6 OF THE 21 SREF MEMBERS HAVE A LOW OF -10 F OR
COLDER AT ST. CLOUD. BASED ON THIS COLD SIGNAL...DID KNOCK A FEW
DEGREES OFF OF ALLBLEND LOWS FOR SUNDAY MORNING. ONLY OTHER CHANGE
MADE FOR SUNDAY WAS TO REMOVE POPS FROM SUNDAY AFTERNOON..AS
PRECIP FROM THE NEXT SYSTEM LOOKS TO ARRIVE IN ERNEST SUNDAY
NIGHT.
AS FOR THAT SUNDAY NIGHT/MONDAY SYSTEM...GFS/ECMWF/GEM CONTINUE
TO SHOW A NEGATIVELY TILTED UPPER WAVE MOVING ACROSS MN/WI MONDAY.
WHAT IS LEADING TO SOME UNCERTAINTY THOUGH WITH THE MODELS IS A
LEAD SRN STREAM SHORTWAVE THAT WILL BE MOVING ACROSS MO ON SUNDAY
AND BE HEADING FOR MICH ON MONDAY. THESE TWO FEATURE WILL PHASE
WITH EACH OTHER AT SOME POINT. ECMWF PHASES THESE SYSTEM MONDAY
AFTERNOON...WHILE THE GFS/GEM ARE ABOUT 12 HOURS BEHIND. WHEN THE
PHASING OCCURS..THIS SFC LOW LOOKS TO DEEPEN BY SEVERAL MB...BUT
THIS DEEPENING LOOKS TO MAINLY HAPPEN TO THE EAST. WHAT THIS WILL
DO THOUGH IS RESULT IN THE DEVELOPMENT IN VERY STRONG WINDS BY
MONDAY AFTERNOON ACROSS WRN AREAS...WITH SUSTAINED WINDS LIKELY
BETWEEN 20 AND 30 MPH...WITH GUSTS POSSIBLY TOPPING 40 MPH. AS FOR
SNOWFALL AMOUNTS...SFC LOW FROM THE ECMWF/GFS LOOKS TO TRACK
ACROSS FROM MORRIS...TO THE NRN TWIN CITIES...TO LADYSMITH WITH
THE MAIN PV ANOMALY GOING ACROSS SRN MN. THIS ALL POINTS TO
CENTRAL MN HAVING THE HIGHEST POTENTIAL FOR SEEING SIGNIFICANT
SNOWS. WITH THE 15.00 RUNS...THE GFS IS GENERALLY PRODUCING 6-9
INCHES OF SNOW...WITH THE ECMWF MORE 4-7. EVEN IF 6 INCH SNOWS ARE
NOT WIDESPREAD...EXPECTED STRONG WINDS MONDAY/MONDAY NIGHT WILL
LIKELY FORCE THE NEED FOR HEADLINES OF SOME VARIETY IN THE FUTURE.
BEHIND THIS SYSTEM BOTH THE GFS/ECMWF SHOW A STRONG REX BLOCK
SETTING UP ACROSS ERN NOAM...WHICH CAUSES AN ARCTIC HIGH WITH SFC
PRESSURES FROM 1030 TO 1040 MB TO MORE OR LESS STAY PARKED OVER
THE CENTER OF THE CONTINENT FOR MUCH OF NEXT WEEK. H85 TEMPS OFF
THE GFS/ECMWF AROUND -10C MUCH OF NEXT WEEK...AND WITH A SFC RIDGE
MORE OR LESS OVERHEAD...DEPENDING ON CLOUD COVER...TUESDAY THROUGH
THURSDAY MORNINGS COULD VERY WILL BRING THREE MORE OPPORTUNITIES
TO SEE BELOW ZERO LOWS. IN ADDITION TO THE WINTER LIKE
LOWS...HIGHS NEXT WEEK WILL BE RUNNING 15 TO 25 DEGS BELOW NORMAL.
IN FACT EVEN LOOKING AT THE CFS...THERE DOES NOT LOOK TO BE ANY
SIGNIFICANT WARM UPS IN SITE POSSIBLY THOUGH THE REST OF THIS
MONTH.
&&
.AVIATION.../12Z TAF ISSUANCE/
PRECIPITATION HAS SPREAD OVER JUST ABOUT THE ENTIRE AREA AT TAF
ISSUANCE TIME. MAINLY FREEZING RAIN IS BEING REPORTED SOUTH OF A
LINE FROM AXN TO STC...RNH...AND EAU WITH SNOW TO THE NORTH. THIS
FZRA/SN LINE WILL SINK SOUTH THIS MORNING AND SHOULD CLEAR MSP
AROUND 14Z. THE FIRST BATCH OF PRECIP WILL SLIDE EAST LATE THIS
MORNING WITH A BREAK EARLY THIS AFTERNOON. LIGHT FOG AND SOME
ON AND OFF LIGHT SNOW SHOULD CONTINUE BEFORE THE SECOND ROUND
ARRIVES LATE THIS AFTERNOON IN THE FORM OF SNOW. VSBYS MAY DROP TO
LIFR LEVELS WITH THIS ROUND. LOOKS LIKE THE MAJORITY OF PRECIP
TODAY AND TONIGHT WILL REMAIN JUST NORTH OF RWF. OTHERWISE...IFR
CONDITIONS EXPECTED FOR THE MAJORITY OF THE TAF PERIOD WITH A
GRADUAL IMPROVEMENT AFTER 06Z TONIGHT.
KMSP...-FZRA SHOULD TRANSITION TO -SN BY 14Z AND TAPER OFF A BIT
EARLY THIS AFTERNOON. THE SECOND ROUND ARRIVES LATE AFTERNOON AND
CONTINUES THROUGH MUCH OF THE EVENING WITH A COUPLE INCHES OF
ACCUMULATION. MVFR CONDS WILL DETERIORATE TO IFR AND LIFR CONDS AT
TIMES TODAY AND THIS EVENING BEFORE A SLOW IMPROVEMENT THEREAFTER.
/OUTLOOK FOR KMSP/
SAT...MVFR WITH -SN POSSIBLE. THEN VFR. WINDS NNW AT 10G15KT.
SUN...VFR EARLY WITH MVFR/IFR AND -SN LATE. WINDS E AT 5-10KT.
BECOMING SE AT 10-15KTS
MON...MVFR/IFR WITH SN. WINDS SE AT 10-15KTS BECOMING WNW AT 20G30KTS
LATE.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL 1 AM CDT SATURDAY FOR ANOKA-BENTON-
BLUE EARTH-BROWN-CARVER-CHIPPEWA-CHISAGO-DAKOTA-DOUGLAS-
GOODHUE-HENNEPIN-ISANTI-KANABEC-KANDIYOHI-LAC QUI PARLE-LE
SUEUR-MCLEOD-MEEKER-MILLE LACS-MORRISON-NICOLLET-POPE-
RAMSEY-REDWOOD-RENVILLE-RICE-SCOTT-SHERBURNE-SIBLEY-STEARNS-
STEELE-STEVENS-SWIFT-TODD-WASECA-WASHINGTON-WRIGHT-YELLOW
MEDICINE.
WI...WINTER WEATHER ADVISORY UNTIL 1 AM CDT SATURDAY FOR BARRON-
CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX.
&&
$$
MPG/BORGHOFF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
444 AM CDT FRI MAR 15 2013
.DISCUSSION...
CERTAINLY WHEN ONE READS THROUGH THE FORECAST FOR THE NEXT
WEEK...THE LAST WORD THAT YOU WOULD ASSOCIATE WITH THIS WEATHER IS
SPRING! HAVE TWO SYSTEMS TO DEAL WITH THIS PERIOD. THE FIRST WILL
COME FROM TWO WAVES SPREAD OUT OVER TODAY AND TONIGHT. FIRST WAVE
THIS MORNING WILL POSE P-TYPE ISSUES...WITH ROUND TWO BRINGING
ANOTHER ROUND OF SNOW FROM LATE THIS AFTERNOON INTO TONIGHT. OTHER
SYSTEM WILL BE A POTENT LOW FOR SUNDAY NIGHT THROUGH MONDAY. AS
FOR TEMPERATURES...THOUGH NORMAL HIGHS ARE NOW RAPIDLY CLIMBING
THROUGH THE 40S...HIGHS THIS WEEKEND INTO NEXT WEEK LOOK TO BE
HEADING BACK INTO THE TEENS AND 20S...WELCOME TO SPRING MN/WI
STYLE!
INTERESTING WEATHER PATTERN UNFOLDING THIS MORNING. RAP H5 ANALYSIS
SHOWS THE POLAR VORTEX MAKING A RETURN TO WRN HUDSON BAY
/WHERE CHURCHILL H5 TEMP LAST NIGHT WAS -45C/ AS A SOMEWHAT FLAT
UPPER RIDGE CENTERED ALONG THE FOOTHILLS OF THE ROCKIES HAS A
RATHER PERTURBED NW FLOW ACROSS THE NRN PLAINS/UPPER MIDWEST. THE
POLAR VORTEX HAS BEEN SENDING ARCTIC AIR BACK SOUTH ACROSS THE
CANADIAN PRAIRIES INTO THIS WARM RIDGE AND AS IT HAS DONE
SO...HAVE REALLY SEEN THERMAL GRADIENTS FROM 925 MB UP THROUGH 500
MB TIGHTEN UP. THIS TIGHTENING OF THE THERMAL GRADIENT HAS INDUCED
STRONG FGEN ALOFT...WITH PRECIP STARTING TO RAPIDLY BREAK OUT FROM
WEST CENTRAL MN BACK THROUGH CENTRAL NODAK. THIS STRONG TEMP
GRADIENT AND FGEN RIBBON WILL REMAIN IN PLACE ACROSS THE REGION
THROUGH TONIGHT AND WILL SERVE AS A FOCUS FOR TWO WAVES OF
PRECIPITATION.
FIRST WAVE OF PRECIP THIS MORNING HAS BEEN REALLY STRUGGLING WITH
DRY AIR AS EVIDENCED BY 00Z SOUNDINGS FROM BIS/ABR/MPX. MODELS HAVE
BEEN A BIT TOO AGGRESSIVE IN BREAKING OUT PRECIP AND CERTAINLY
CURRENT GRIDS MAY BE A LITTLE AGGRESSIVE WITH ERN EXTENT OF PRECIP
RIGHT OUT THE GATES AT 12Z. OF COURSE BESIDE THE DRY AIR...OTHER
ISSUE WITH THE 00Z SOUNDING FOR MPX WAS THE WARM NOSE CENTERED AT
860 MB OF +6C. FORECAST SOUNDING FROM THE RAP/NAM SHOW THAT THIS
ABOVE ZERO WARM NOSE IS STILL MOSTLY IN PLACE THIS MORNING...WITH
THE THREAT FOR FREEZING RAIN CERTAINLY THERE. THOUGH THE
TEMPERATURE IN THE WARM NOSE IS WELL ABOVE FREEZING...WITH DRY AIR
IN PLACE...BOTH THE RAP AND NAM SHOW THE VERTICAL PROFILE OF THE
WET BULB TEMPERATURE IS MORE OR LESS NEAR OR BELOW ZERO FOR MOST
AREAS NORTHEAST OF THE UPPER MN RIVER. AS ATMO MOISTENS FROM TOP
DOWN...EVAP COOLING SHOULD QUICKLY BEAT BACK THIS WARM NOSE...WITH
PRECIP STARTING OUT AS A COUPLE OF HOURS OF FZRA/SN BEFORE GOING
ALL SNOW. BASED ON A RAP/NAM/GEM BLEND EXPECT THIS FIRST ROUND OF
PRECIP TO MAINLY FALL ALONG AND NORTHEAST OF THE MN RIVER...AND BE
BASICALLY CENTERED ON THE I-94 CORRIDOR. SNOW TOTALS ARE A TOUGH
CALL WITH THIS WAVE...AS INITIAL FZRA WILL TAKE A BITE OUT OF SNOW
TOTALS...BUT GENERALLY EXPECT 1-3 INCHES WITH THIS.
EXPECT ABOUT A 4 HOUR LULL BETWEEN FIRST AND SECOND ROUND OF SNOW
AND TRIED TIMING THIS LULL ACROSS THE AREA ON A NAM/GEM TIMING.
WITH THE SAME NAM/GEM BLEND...EXPECT ROUND TWO TO MOVE INTO THE NW
CWA AROUND 20Z AND PUSH BACK INTO WRN WI AROUND 00Z.
FORTUNATELY...BY THE TIME THIS SECOND PUSH OF PRECIP ARRIVES...
CONTINUOUS CAA THROUGH THE DAY WILL MAKE THIS AN ALL SNOW
FEATURE. MODELS SHOW THIS FEATURE TRACKING SLIGHTLY FARTHER SOUTH
OF THE FIRST ONE...BUT AGAIN...PRECIP CHANCES LOOK BEST ALONG
NORTH OF GRANITE FALLS/MANKATO/LA CROSSE LINE. SINCE THIS WAVE
WILL BE ALL SNOW...WILL HAVE TO POTENTIAL TO PRODUCE SLIGHT HIGHER
ACCUMS IN THE 2-4 INCH RANGE. WITH THIS FORECAST PACKAGE...HAVE
BASICALLY 2-4 INCHES OF STORM TOTAL SNOW NE OF A
MORRIS/LITCHFIELD/NORTHFIELD LINE. BASED ON THESE CHANGES...SRN ROWS
OF COUNTIES IN ADVY MAY BE QUESTIONABLE...BUT WITH MODELS SUCH AS
THE GFS/HIRES-ARW SHOWING SNOW OCCURRING A BIT FARTHER SOUTH
TONIGHT...IMPACTING THE SRN END OF THE ADVY...DECIDED THERE IS
ENOUGH UNCERTAINTY WITH WHERE THE SECOND WAVE GOES TO KEEP THE
ADVY UNCHANGED.
BEHIND THIS SYSTEM...ARCTIC HIGH SHOWS UP FOR THE WEEKEND. THIS
WILL DRY THINGS OUT FOR ST. PATRICK`S DAY WEEKEND...BUT WILL HAVE
TO WATCH LOWS FOR SUNDAY MORNING. CLOUDS LOOK TO HOLD TIGHT
THROUGH SATURDAY...BUT SATURDAY NIGHT SKIES LOOK TO CLEAR OUT AS A
1028 MB HIGH MOVES OVER NE MN. THIS COULD SET THE STAGE FOR MORE
BELOW ZERO LOWS...ESPECIALLY ACROSS CENTRAL MN. IN FACT...FOR
SUNDAY MORNING...6 OF THE 21 SREF MEMBERS HAVE A LOW OF -10 F OR
COLDER AT ST. CLOUD. BASED ON THIS COLD SIGNAL...DID KNOCK A FEW
DEGREES OFF OF ALLBLEND LOWS FOR SUNDAY MORNING. ONLY OTHER CHANGE
MADE FOR SUNDAY WAS TO REMOVE POPS FROM SUNDAY AFTERNOON..AS
PRECIP FROM THE NEXT SYSTEM LOOKS TO ARRIVE IN ERNEST SUNDAY
NIGHT.
AS FOR THAT SUNDAY NIGHT/MONDAY SYSTEM...GFS/ECMWF/GEM CONTINUE
TO SHOW A NEGATIVELY TILTED UPPER WAVE MOVING ACROSS MN/WI MONDAY.
WHAT IS LEADING TO SOME UNCERTAINTY THOUGH WITH THE MODELS IS A
LEAD SRN STREAM SHORTWAVE THAT WILL BE MOVING ACROSS MO ON SUNDAY
AND BE HEADING FOR MICH ON MONDAY. THESE TWO FEATURE WILL PHASE
WITH EACH OTHER AT SOME POINT. ECMWF PHASES THESE SYSTEM MONDAY
AFTERNOON...WHILE THE GFS/GEM ARE ABOUT 12 HOURS BEHIND. WHEN THE
PHASING OCCURS..THIS SFC LOW LOOKS TO DEEPEN BY SEVERAL MB...BUT
THIS DEEPENING LOOKS TO MAINLY HAPPEN TO THE EAST. WHAT THIS WILL
DO THOUGH IS RESULT IN THE DEVELOPMENT IN VERY STRONG WINDS BY
MONDAY AFTERNOON ACROSS WRN AREAS...WITH SUSTAINED WINDS LIKELY
BETWEEN 20 AND 30 MPH...WITH GUSTS POSSIBLY TOPPING 40 MPH. AS FOR
SNOWFALL AMOUNTS...SFC LOW FROM THE ECMWF/GFS LOOKS TO TRACK
ACROSS FROM MORRIS...TO THE NRN TWIN CITIES...TO LADYSMITH WITH
THE MAIN PV ANOMALY GOING ACROSS SRN MN. THIS ALL POINTS TO
CENTRAL MN HAVING THE HIGHEST POTENTIAL FOR SEEING SIGNIFICANT
SNOWS. WITH THE 15.00 RUNS...THE GFS IS GENERALLY PRODUCING 6-9
INCHES OF SNOW...WITH THE ECMWF MORE 4-7. EVEN IF 6 INCH SNOWS ARE
NOT WIDESPREAD...EXPECTED STRONG WINDS MONDAY/MONDAY NIGHT WILL
LIKELY FORCE THE NEED FOR HEADLINES OF SOME VARIETY IN THE FUTURE.
BEHIND THIS SYSTEM BOTH THE GFS/ECMWF SHOW A STRONG REX BLOCK
SETTING UP ACROSS ERN NOAM...WHICH CAUSES AN ARCTIC HIGH WITH SFC
PRESSURES FROM 1030 TO 1040 MB TO MORE OR LESS STAY PARKED OVER
THE CENTER OF THE CONTINENT FOR MUCH OF NEXT WEEK. H85 TEMPS OFF
THE GFS/ECMWF AROUND -10C MUCH OF NEXT WEEK...AND WITH A SFC RIDGE
MORE OR LESS OVERHEAD...DEPENDING ON CLOUD COVER...TUESDAY THROUGH
THURSDAY MORNINGS COULD VERY WILL BRING THREE MORE OPPORTUNITIES
TO SEE BELOW ZERO LOWS. IN ADDITION TO THE WINTER LIKE
LOWS...HIGHS NEXT WEEK WILL BE RUNNING 15 TO 25 DEGS BELOW NORMAL.
IN FACT EVEN LOOKING AT THE CFS...THERE DOES NOT LOOK TO BE ANY
SIGNIFICANT WARM UPS IN SITE POSSIBLY THOUGH THE REST OF THIS
MONTH.
&&
.AVIATION.../06Z TAF ISSUANCE/
VERY CHALLENGING FORECAST PERIOD WITH TWO ROUNDS OF PRECIP. THE
FIRST ROUND WILL BE THIS MORNING...AND A WARM LAYER ABOVE GROUND
WILL MELT THE FALLING SNOW...WITH FREEZING RAIN EXPECTED THIS
MORNING. THE PRECIP WILL TRANSITION TO SNOW LATER THIS MORNING.
THERE WILL BE A BREAK IN THE PRECIP MID DAY AS VFR/IFR CEILINGS
WILL SETTLE IN...BUT ANOTHER ROUND OF SNOW WILL MOVE ALONG THE
I-94 CORRIDOR AND BRING VISBYS DOWN TO A MILE. CONFIDENCE IS
HIGHER THAT THIS SECOND ROUND WILL BE ALL SNOW. LOW CEILINGS WILL
LINGER THROUGH FRIDAY NIGHT.
KMSP...
THE 00Z SOUNDING SHOWED 6C (43F) AROUND 3500FT AGL...SO THIS WARM
LAYER WILL MELT ANY PRECIP THAT FALLS THROUGH IT. SURFACE TEMPS
WILL FALL BELOW FREEZING...SO EXPECTING FREEZING RAIN THIS
MORNING...SO WILL LIKELY NEED AN AWW. SURFACE TEMPS WILL RISE
ABOVE FREEZING AROUND 13/14Z...AND EVENTUALLY THAT AFOREMENTIONED
WARM LAYER WILL COOL AND WILL SEE A TRANSITION TO RASN...AND SN BY
MID DAY. THERE WILL BE LULL IN THE PRECIP...BEFORE ANOTHER ROUND
OF SNOW MOVE ACROSS THE METRO DURING THE LATE AFTERNOON/EARLY
EVENING.
/OUTLOOK FOR KMSP/
SAT...MVFR WITH -SN POSSIBLE. THEN VFR. WINDS NNW AT 10G15KT.
SUN...VFR EARLY WITH MVFR/IFR AND -SN LATE. WINDS E AT 05G10KT.
BECOMING SE AT 10G15KT
MON...MVFR/IFR WITH SN. WINDS SE AT 10KTS BECOMING WNW AT 20G25KT
LATE.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL 1 AM CDT SATURDAY FOR ANOKA-BLUE
EARTH-BROWN-CARVER-CHISAGO-DAKOTA-GOODHUE-HENNEPIN-ISANTI-
KANABEC-LE SUEUR-MCLEOD-MILLE LACS-NICOLLET-RAMSEY-RICE-
SCOTT-SHERBURNE-SIBLEY-STEELE-WASECA-WASHINGTON-WRIGHT.
WINTER WEATHER ADVISORY UNTIL 1 AM CDT SATURDAY FOR BENTON-
CHIPPEWA-DOUGLAS-KANDIYOHI-LAC QUI PARLE-MEEKER-MORRISON-
POPE-REDWOOD-RENVILLE-STEARNS-STEVENS-SWIFT-TODD-YELLOW
MEDICINE.
WI...WINTER WEATHER ADVISORY UNTIL 1 AM CDT SATURDAY FOR BARRON-
CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX.
&&
$$
MPG/JRB
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1007 PM EDT SAT MAR 16 2013
.SYNOPSIS...
TONIGHT, HIGH PRESSURE WILL BUILD INTO THE AREA BRINGING DRIER
AIR AND JUST A FEW LIGHT SNOW SHOWERS AND FLURRIES. THE NEXT
WEATHER MAKER FOR THE AREA WILL BE A COMPLEX LOW PRESSURE SYSTEM
OVER THE GREAT LAKES AND MID ATLANTIC COAST MONDAY AND TUESDAY.
THIS SYSTEM WILL BRING SNOW OR MIXED PRECIPITATION TO THE AREA
BEGINNING LATE MONDAY AND CONTINUING INTO TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
1008 PM UPDATE...
LAST FLURRIES ARE TAPERING OFF ON SCHEDULE, AND IR SAT SHOWS THE
FORECAST CLEARING IS BEGINNING FROM NORTHWEST TO SOUTHEAST. HAVE
MADE SOME MINOR ADJUSTMENTS TO THE TEMPERATURE GRIDS, TIMING THE
FALL OFF COINCIDENT WITH THE RAPID CLEARING. EXISTING FORECAST
REMAINS IN VERY GOOD SHAPE.
610 PM UPDATE...
LIGHT SNOW SHOWERS ARE PROVING TO BE STUBBORN HEADING INTO THE
EVENING HOURS. AFTER CHECKING THE LATEST RAP FIELDS, DECIDED TO
KEEP CHC POPS AROUND FOR A FEW EXTRA HOURS THIS EVENING. GRIDS
LOOK TO BE IN GOOD SHAPE, SO JUST A MINOR UPDATE.
3 PM UPDATE...
BACK EDGE OF THE LGT SNOW MVG RAPIDLY ACROSS CNTRL PA ATTM
AND WILL BRING AN END TO THE SNOW QUICKLY THIS AFTN. HWVR...CRNTS
UPSTREAM SHOW PLENTY OF CLDS AND LL MOISTURE HANGING BACK ALONG
THE FNTL BNDRY. SO...DONT XPCT RAPID CLRG THIS EVE...AND A FEW LGT
FLURRIES COULD LINGER THRU THE NGT. FB RPTS HAVE BEEN ANYWHERE
FROM A TRACE TO TWO INCHES SO FAR...SO WITH THE BACK EDGE MVVG
RAPIDLY EAST...REALLY NO NEED FOR ANY FLAGS WITH THIS EVENT. TEMPS
THIS EVE WILL DROP INTO THE MID TEENS OR LWR IN MANY PLACES WITH
CAA BHD THE LOW. MODEL GUID IN GOOD AGREEMENT ON MINS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
SCNDRY TROF/COLD FNT PASSES EARLY SUN MRNG AND MAY BRING SOME LGT
SNOW SHWRS TO THE NRN ZONES. MUCH DRIER AIR BHD THIS TROF SHD
ALLOW FOR GRADUAL CLRG SUN AFTN...WITH LIMITED LAKE CLDS AND
FLURRIES DUE TO THE VERY DRY AIR AND WEAK INSTABILITY OFF THE COLD
LAKE.
1028MB HIGH SLIDES SLOWLY EAST INTO NEW ENG BY EARLY MON. THIS
WILL PROVIDE THE COLD AIR AND BAROCLINIC ZONE THAT HELP DEEPENTHE
SCNDRY LOW THAT DVLPS LATE MON. OLD LOW MVES WELL WEST INTO THE
WRN LAKES...BUT WITH THIS BLOCKING HI...COLD AIR WILL BE SLOW TO
LEAVE AND WILL BE REENFORCED BY THE DVLPG CSTL LOW. THIS WILL
ALLOW SNOW TO BRK OUT FROM WEST TO EAST LATE MON AND CONT INTO
EARLY TUE. INITIAL BURST OF WAA SNOW COULD BE MODERATELY HEAVY MON
EVE. NAM HAS NOW MVD INTO THE EURO/S CAMP AND KEEPS THE AREA
COLDER THRU THE EVENT. MODEL FCST PROFILES GNRLY SUPPORT ALL SNOW
NORTH OF THE NY/PA BRDR AND EAST OF I81. TO THE SOUTH AND
WEST...WRM LAYR SHD ALLOW A CHG TO FRZG RAIN...WITH THE COLD AIR
DAMMING...DOES NOT LOOK LIKE TEMOPS WILL GET ABC FRZG...EVEN OVER
NE PA...THRU 12Z TUE.
LOW WILL MVE RAPIDLY EAST SO THE CHANCE FOR WRAP ARND SNOW FROM
THE CSTL TUE WILL BE LIMITED. ATTM...SNOWFALL AND ANY ICE AMTS
LOOK TO BE PRETTY SOLIDLY IN THE ADVISORY CATEGORY WO WILL NOT BE
ISSUING ANY FLAGS AND JUST CONT THE MENTION IN THE HWO.
GNRLY FLWD THE COLDER NAM GUID FOR THE GRIDS AS THE GFS BASED MAV
SEEMED TOO WARM.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
2 PM SAT UPDATE...
FOLLOWED WPC GUIDANCE. COLDER THAN NORMAL WITH MORE SNOW SHOWERS.
MODELS ARE SIMILAR. A NOREASTER MOVES NE INTO EASTERN NEW ENGLAND
TUESDAY NIGHT BUT A LARGE UPPER LEVEL LOW REMAINS OVER THE
NORTHEAST US AT LEAST THROUGH FRIDAY. THIS TROF KEEPS THE BIG
STORMS TO THE S0UTH BUT WILL KEEP COLD AIR OVER THE AREA. IT WILL
BE COLD ENOUGH FOR LAKE ENHANCEMENT. SLOW WARMING LATE IN THE
WEEK.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
SFC LOW PRES OVER THE MID ATLANTIC IS MOVING OFF THE COAST ATTM AS
LIGHT SNOW ACROSS CENTRAL NY AND NE PA ENDS. BEHIND THIS WAVE A
NORTHWEST FLOW OF COLD AIR WILL PREVAIL THROUGH THIS TAF PERIOD.
FOR THE NEXT FEW HOURS AS FLURRIES AND LOW LEVEL MOISTURE BEHIND
THIS WAVE LINGERS MVFR CIGS ARE POSSIBLE AT KITH/KBGM/KAVP THROUGH
03Z. SOME DRYING OVERNIGHT WILL KEEP CONDITIONS AT LOW VFR CIGS
FOLLOWED BY INCREASING LOW LEVEL MOISTURE LATE TONIGHT EARLY
SUNDAY MORNING WITH CONDITIONS COLD ENOUGH FOR MINOR LAKE ENHANCED
SNOW SHOWERS. MVFR CIGS WILL ONCE AGAIN BE COMMON AT ALL
TERMINALS BETWEEN 08Z-14Z, EXCEPT FOR KAVP. AT KSYR/KRME/KITH,
MVFR VSBY RESTRICTIONS ARE ALSO POSSIBLE DUE TO SNOW SHOWERS. BY
MID MORNING CONDITIONS AT ALL SITES WILL IMPROVE TO VFR WITH CIGS
AROUND 4K FT.
NORTHWEST WINDS AT 5 TO 10 KNOTS..
.OUTLOOK...
SUN NIGHT TO MON MORN...MAINLY VFR.
MIDDAY MON TO TUE PM...MVFR/IFR RESTRICTIONS LIKELY...IN MIXED
PRECIP.
TUE NGT TO THU...MVFR/VFR WITH SCT SNOW SHWRS...MOSTLY IN NY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DGM
NEAR TERM...DGM/DJP
SHORT TERM...DGM
LONG TERM...TAC
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
806 PM EDT SAT MAR 16 2013
.SYNOPSIS...
TONIGHT, HIGH PRESSURE WILL BUILD INTO THE AREA BRINGING DRIER
AIR AND JUST A FEW LIGHT SNOW SHOWERS AND FLURRIES. THE NEXT
WEATHER MAKER FOR THE AREA WILL BE A COMPLEX LOW PRESSURE SYSTEM
OVER THE GREAT LAKES AND MID ATLANTIC COAST MONDAY AND TUESDAY.
THIS SYSTEM WILL BRING SNOW OR MIXED PRECIPITATION TO THE AREA
BEGINNING LATE MONDAY AND CONTINUING INTO TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
610 PM UPDATE...
LIGHT SNOW SHOWERS ARE PROVING TO BE STUBBORN HEADING INTO THE
EVENING HOURS. AFTER CHECKING THE LATEST RAP FIELDS, DECIDED TO
KEEP CHC POPS AROUND FOR A FEW EXTRA HOURS THIS EVENING. GRIDS
LOOK TO BE IN GOOD SHAPE, SO JUST A MINOR UPDATE.
3 PM UPDATE...
BACK EDGE OF THE LGT SNOW MVG RAPIDLY ACROSS CNTRL PA ATTM
AND WILL BRING AN END TO THE SNOW QUICKLY THIS AFTN. HWVR...CRNTS
UPSTREAM SHOW PLENTY OF CLDS AND LL MOISTURE HANGING BACK ALONG
THE FNTL BNDRY. SO...DONT XPCT RAPID CLRG THIS EVE...AND A FEW LGT
FLURRIES COULD LINGER THRU THE NGT. FB RPTS HAVE BEEN ANYWHERE
FROM A TRACE TO TWO INCHES SO FAR...SO WITH THE BACK EDGE MVVG
RAPIDLY EAST...REALLY NO NEED FOR ANY FLAGS WITH THIS EVENT. TEMPS
THIS EVE WILL DROP INTO THE MID TEENS OR LWR IN MANY PLACES WITH
CAA BHD THE LOW. MODEL GUID IN GOOD AGREEMENT ON MINS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
SCNDRY TROF/COLD FNT PASSES EARLY SUN MRNG AND MAY BRING SOME LGT
SNOW SHWRS TO THE NRN ZONES. MUCH DRIER AIR BHD THIS TROF SHD
ALLOW FOR GRADUAL CLRG SUN AFTN...WITH LIMITED LAKE CLDS AND
FLURRIES DUE TO THE VERY DRY AIR AND WEAK INSTABILITY OFF THE COLD
LAKE.
1028MB HIGH SLIDES SLOWLY EAST INTO NEW ENG BY EARLY MON. THIS
WILL PROVIDE THE COLD AIR AND BAROCLINIC ZONE THAT HELP DEEPENTHE
SCNDRY LOW THAT DVLPS LATE MON. OLD LOW MVES WELL WEST INTO THE
WRN LAKES...BUT WITH THIS BLOCKING HI...COLD AIR WILL BE SLOW TO
LEAVE AND WILL BE REENFORCED BY THE DVLPG CSTL LOW. THIS WILL
ALLOW SNOW TO BRK OUT FROM WEST TO EAST LATE MON AND CONT INTO
EARLY TUE. INITIAL BURST OF WAA SNOW COULD BE MODERATELY HEAVY MON
EVE. NAM HAS NOW MVD INTO THE EURO/S CAMP AND KEEPS THE AREA
COLDER THRU THE EVENT. MODEL FCST PROFILES GNRLY SUPPORT ALL SNOW
NORTH OF THE NY/PA BRDR AND EAST OF I81. TO THE SOUTH AND
WEST...WRM LAYR SHD ALLOW A CHG TO FRZG RAIN...WITH THE COLD AIR
DAMMING...DOES NOT LOOK LIKE TEMOPS WILL GET ABC FRZG...EVEN OVER
NE PA...THRU 12Z TUE.
LOW WILL MVE RAPIDLY EAST SO THE CHANCE FOR WRAP ARND SNOW FROM
THE CSTL TUE WILL BE LIMITED. ATTM...SNOWFALL AND ANY ICE AMTS
LOOK TO BE PRETTY SOLIDLY IN THE ADVISORY CATEGORY WO WILL NOT BE
ISSUING ANY FLAGS AND JUST CONT THE MENTION IN THE HWO.
GNRLY FLWD THE COLDER NAM GUID FOR THE GRIDS AS THE GFS BASED MAV
SEEMED TOO WARM.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
2 PM SAT UPDATE...
FOLLOWED WPC GUIDANCE. COLDER THAN NORMAL WITH MORE SNOW SHOWERS.
MODELS ARE SIMILAR. A NOREASTER MOVES NE INTO EASTERN NEW ENGLAND
TUESDAY NIGHT BUT A LARGE UPPER LEVEL LOW REMAINS OVER THE
NORTHEAST US AT LEAST THROUGH FRIDAY. THIS TROF KEEPS THE BIG
STORMS TO THE S0UTH BUT WILL KEEP COLD AIR OVER THE AREA. IT WILL
BE COLD ENOUGH FOR LAKE ENHANCEMENT. SLOW WARMING LATE IN THE
WEEK.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
SFC LOW PRES OVER THE MID ATLANTIC IS MOVING OFF THE COAST ATTM AS
LIGHT SNOW ACROSS CENTRAL NY AND NE PA ENDS. BEHIND THIS WAVE A
NORTHWEST FLOW OF COLD AIR WILL PREVAIL THROUGH THIS TAF PERIOD.
FOR THE NEXT FEW HOURS AS FLURRIES AND LOW LEVEL MOISTURE BEHIND
THIS WAVE LINGERS MVFR CIGS ARE POSSIBLE AT KITH/KBGM/KAVP THROUGH
03Z. SOME DRYING OVERNIGHT WILL KEEP CONDITIONS AT LOW VFR CIGS
FOLLOWED BY INCREASING LOW LEVEL MOISTURE LATE TONIGHT EARLY
SUNDAY MORNING WITH CONDITIONS COLD ENOUGH FOR MINOR LAKE ENHANCED
SNOW SHOWERS. MVFR CIGS WILL ONCE AGAIN BE COMMON AT ALL
TERMINALS BETWEEN 08Z-14Z, EXCEPT FOR KAVP. AT KSYR/KRME/KITH,
MVFR VSBY RESTRICTIONS ARE ALSO POSSIBLE DUE TO SNOW SHOWERS. BY
MID MORNING CONDITIONS AT ALL SITES WILL IMPROVE TO VFR WITH CIGS
AROUND 4K FT.
NORTHWEST WINDS AT 5 TO 10 KNOTS..
.OUTLOOK...
SUN NIGHT TO MON MORN...MAINLY VFR.
MIDDAY MON TO TUE PM...MVFR/IFR RESTRICTIONS LIKELY...IN MIXED
PRECIP.
TUE NGT TO THU...MVFR/VFR WITH SCT SNOW SHWRS...MOSTLY IN NY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DGM
NEAR TERM...DGM/DJP
SHORT TERM...DGM
LONG TERM...TAC
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BUFFALO NY
742 AM EDT FRI MAR 15 2013
.SYNOPSIS...
LOW PRESSURE TRACKING ACROSS SOUTHERN ONTARIO WILL BRING SOME SNOW
SHOWERS TO THE REGION TODAY...THEN ANOTHER LOW PASSING TO THE SOUTH
WILL CONTINUE THIS RISK FOR THE SOUTHERN TIER ON SATURDAY. ANY SNOW
ACCUMULATIONS WILL BE LIGHT...WITH A RETURN TO DRY WEATHER ON
SUNDAY. OTHERWISE...TEMPERATURES ARE EXPECTED TO REMAIN ON THE COOL
SIDE FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
A CLIPPER LOW EMBEDDED IN A NORTHWESTERLY FLOW AT 500 MB WILL DIVE
SOUTHWARD OUT OF CANADA AND INTO NORTHERN NEW YORK THIS
AFTERNOON. MOISTURE IS QUITE LIMITED WITH THIS SYSTEM...BUT THERE
IS AN AREA OF LIFT ASSOCIATED WITH WARM AIR ADVECTION IN THE MID-
LEVELS WHICH EXTENDS SOUTH OF THE LOW. AT DAYBREAK...RADAR SHOWS
ITS STRONGEST RETURNS ALOFT...BUT IN GENERAL SUPPORTS MODEL
GUIDANCE WHICH FORECAST SNOW TO START AROUND OR SHORTLY AFTER 12Z.
WHILE RADAR RETURNS ARE INITIALLY VIRGA...PERSISTENT LIFT WILL
RESULT IN SNOW REACHING THE GROUND BY MID-MORNING IN MOST SPOTS
WEST OF ROCHESTER.
06Z RUNS OF THE NAM AND GFS AND SEVERAL RUNS OF THE HRRR ALL TREND
SLIGHTLY NORTHWARD WITH QPF...AND A BIT HIGHER. THE HIGHER QPFS
APPEAR OVERDONE WHEN COMPARED WITH OBSERVED CONDITIONS...BUT
THE SLIGHTLY NORTHWARD PLACEMENT TRENDS SEEM CORRECT BASED ON
RADAR OBSERVATIONS. WHILE CONFIDENCE IS FAIRLY HIGH THAT SOME
SNOW WILL FALL...ACCUMULATIONS IN WESTERN NEW YORK WILL ALMOST
CERTAINLY BE LIGHT. ALSO...THE MARCH SUN ANGLE SHOULD LIMIT SNOW
ACCUMULATIONS...WITH LIGHT SNOW PROBABLY MAINLY ACCUMULATING ON
GRASSY SURFACES. EXPECT LESS THAN AN INCH IN MOST LOCATIONS...WITH
PERHAPS AN INCH OR TWO ACROSS SLIGHTLY HIGHER TERRAIN IN ERIE AND
WYOMING COUNTIES...WHERE THE BEST LIFT IS EXPECTED.
WITH THE LOW A FAIRLY VIGOROUS SHORTWAVE ALOFT WILL DIVE ACROSS
THE NORTH COUNTRY THIS AFTERNOON. 850 MB TEMPERATURES ARE COLD
ENOUGH THAT IN COMBINATION WITH THE SHORTWAVE THERE PROBABLY WILL
BE SOME LAKE ENHANCEMENT. BECAUSE OF THIS...SNOW SHOWERS MAY BE A
BIT MORE INTENSE BUT ALSO MORE HIT OR MISS. SO WHILE ACCUMULATIONS
WILL VARY...THESE SNOW SHOWERS WILL HAVE A GREATER POTENTIAL TO
LOCALIZED SNOW ACCUMULATIONS OF A COUPLE INCHES.
OTHERWISE...EXPECT ANOTHER CHILLY DAY...WITH HIGHS IN THE MID TO
UPPER 30S IN MOST LOCATIONS. AN ASSOCIATED COLD FRONT WILL PASS
LATE AFTERNOON...WHICH MAY BRING ANOTHER BRIEF PERIOD OF SNOW SHOWERS.
FOR TONIGHT...LOW PRESSURE WILL TRACK ALONG A STALLED FRONTAL
BOUNDARY...WHICH IS FORECAST TO STAY TO THE SOUTH OF OUR REGION.
THERE IS A CHANCE SOME SNOW SHOWERS WILL SNEAK INTO FAR SOUTHERN
PORTIONS OF THE SOUTHERN TIER. OTHERWISE...LINGERING SNOW SHOWERS
EAST OF LAKE ONTARIO SHOULD TAPER OFF AFTER MIDNIGHT. IN BOTH CASES
ANY SNOW ACCUMULATION WOULD BE NEGLIGIBLE...WITH DRY WEATHER
EXPECTED FOR THE VAST MAJORITY OF WESTERN NEW YORK TONIGHT. FAIRY
PERSISTENT CLOUD COVER SHOULD LIMIT RADIATIONAL COOLING
TONIGHT...WITH LOWS MAINLY IN THE LOWER TO MID 20S...UPPER TEENS EAST
OF LAKE ONTARIO.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
FOR THIS PERIOD LARGELY QUIET CONDITIONS THROUGH THE WEEKEND...AND
CONTINUED CHILLY.
SATURDAY MORNING A FRONTAL BOUNDARY WILL BE TO OUR SOUTH...JUST
SOUTH OF THE MASON-DIXON LINE. SEVERAL SURFACE WAVES RIDING ALONG
THIS FRONTAL BOUNDARY WILL BRING CHANCES FOR LIGHT SNOW ACROSS THE
SOUTHERN TIER. SOME OF THE COLDEST AIR (-32C) AT 850 HPA IN THE
NORTHERN HEMISPHERE WILL BE BUILDING SOUTHWARD TO NEAR JAMES BAY FOR
THE START OF THE WEEKEND. WHILE WE WILL NOT SEE 850 HPA TEMPERATURES
THIS LOW...HIGH PRESSURE ASSOCIATED WITH THIS COLD POOL WILL BRING A
CHILLY NORTHERLY FLOW FROM CANADA ACROSS THE REGION SATURDAY. THIS
FLOW WILL KEEP TEMPERATURES 10 DEGREES OR SO BELOW NORMAL THROUGH
THE DAY...AND WITH THE UPSLOPE FLOW SOUTH OF LAKE ONTARIO A PASSING
FLURRY IS POSSIBLE SOUTH OF LAKE ONTARIO.
SATURDAY NIGHT AND SUNDAY THIS HIGH PRESSURE FROM CANADA WILL BUILD
SOUTHWARD TOWARDS THE EASTERN GREAT LAKES REGION. MOISTURE LINGERING
IN THE LOWER LAYERS WILL LIKELY KEEP PARTLY CLOUDY SKIES THROUGH
SATURDAY NIGHT...THOUGH THINNING MOISTURE WILL ALLOW FOR INCREASING
AMOUNTS OF SUNSHINE ON SUNDAY. TEMPERATURES SATURDAY NIGHT AND
SUNDAY WILL STILL AVERAGE 5 TO 10 DEGREES BELOW MID MARCH NORMALS.
SUNDAY NIGHT SHOULD SEE MUCH OF THE AREA CLEARING OUT WITH AGAIN
COLD TEMPERATURES AS THE SURFACE HIGH NEARS THE REGION. WITH THE
LIGHT WINDS AND CLEAR SKIES GOOD RADIATIONAL COOLING CONDITIONS WILL
ALLOW TEMPERATURES TO DROP QUICKLY. OVERNIGHT LOWS WILL DROP INTO
THE TEENS...WITH A FEW LOW 20S ACROSS THE LAKE PLAIN. ACROSS THE
NORTH COUNTRY TEMPERATURES ARE EXPECTED TO DROP INTO THE LOW TEENS
UNDER CLEAR SKIES.
BY LATE SUNDAY NIGHT THE HIGH PRESSURE WILL BE SLIDING TO THE EAST
AND ALLOW FOR MOISTURE TO INCREASE FROM THE SOUTHWEST. THIS WILL
BRING INCREASING LATE TOWARDS SOUTHWESTERN NEW YORK. ANY
PRECIPITATION WILL LIKELY REMAIN JUST TO THE SOUTH AND WEST OF OUR
CWA.
AN UPPER LEVEL SHORTWAVE WILL BE CROSSING THE NORTH COUNTRY SUNDAY
NIGHT...BUT WITH LITTLE MOISTURE IN THE LOWER LEVELS AND THE
MOISTURE THAT IS MOVING INTO THE CWA REMAINING WELL TO THE SOUTH
EXPECT A DRY SUNDAY NIGHT HERE.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE MAIN FOCUS FOR THIS PERIOD CONTINUES TO BE ON THE DEVELOPMENT OF
A LARGE STORM SYSTEM OVER THE NATION/S MID-SECTION SUNDAY
NIGHT...THE RESULT OF THE PHASING OF NORTHERN AND SOUTHERN STREAM
DISTURBANCES. MODELS ARE IN GOOD AGREEMENT ON THE BASIC PICTURE WITH
A LARGE LOW PRESSURE SYSTEM CONSOLIDATING OVER THE WESTERN GREAT
LAKES BY MONDAY EVENING. THIS WILL RESULT IN THE AFOREMENTIONED
BAROCLINIC ZONE BEING ADVECTED NORTHWARDS ACROSS WESTERN/CENTRAL NEW
YORK...BRINGING WARMING TEMPERATURES INTO THE MID TO UPPER 30S.
INCREASING SOUTHERLY/DOWNSLOPING WINDS MAY EVEN PUSH AREAS NEAR THE
LAKES INTO THE LOWER 40S MONDAY AFTERNOON. THE WARM UP WILL COME AT A
PRICE HOWEVER AS PRECIPITATION WILL ACCOMPANY THE WARM FRONTAL
PASSAGE. AT THIS POINT IT APPEARS THAT MOST AREAS SHOULD SEE A BRIEF
PERIOD OF SNOW AHEAD OF THE WARM FRONT FOLLOWED BY A RAPID
TRANSITION OVER TO RAIN AS THE LOW LEVELS WARM SIGNIFICANTLY. BY
MONDAY NIGHT MOST AREAS SHOULD BE SEEING RAIN...A POTENTIALLY QUITE
A BIT AT THAT WITH QPF RUNNING IN THE NEIGHBORHOOD OF ONE QUARTER TO
THREE QUARTERS OF AN INCH.
EXPECT A TRANSITION FROM RAIN BACK TO SNOW AGAIN TUESDAY AS THE LOW
PRESSURE SYSTEM TRACKS ACROSS THE UPPER SAINT LAWRENCE
VALLEY...MERGING WITH A SECONDARY COASTAL LOW OVER NEW ENGLAND AND
SWINGING A COLD FRONT ACROSS THE LOWER GREAT LAKES. THE COMBINATION
OF THE UPPER LEVEL TROUGH MOVING OVERHEAD AND THE INCREASING COLD
ADVECTION WILL MEAN WIDESPREAD SNOW SHOWERS ACROSS THE REGION
DEVELOPING TUESDAY AND LINGERING WELL INTO WEDNESDAY AS TEMPERATURES
DIP BACK BELOW NORMAL.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
WHILE RADAR RETURNS ARE INITIALLY VIRGA...PERSISTENT LIFT WILL
RESULT IN SNOW EVENTUALLY MAKING IT TO THE GROUND AT BUF/IAG...AND
EVENTUALLY AT JHW/ROC AS WELL. SNOW WILL BE ON THE LIGHT
SIDE...MARGINALLY HEAVY ENOUGH TO LOWER VSBY TO 2SM OR LESS. THE
STEADIEST SNOW WILL FALL MID-MORNING THROUGH EARLY AFTERNOON.
AFTER THIS...THERE MAY BE ANOTHER ROUND OF SNOW SHOWERS WITH A
COLD FRONTAL PASSAGE.
AT ART...EXPECT MORE SPORADIC SNOW SHOWERS AS THE UPPER LEVEL
DISTURBANCE KEYS THE PRECIPITATION. CONDITIONS WILL BE MORE
VARIABLE...BUT POTENTIALLY BRIEFLY BELOW 1SM IN SNOW SHOWERS.
CONDITIONS SHOULD IMPROVE AT ALL TAF SITES FOLLOWING THE FRONTAL
PASSAGE WHICH WILL DROP FROM NORTH TO SOUTH BETWEEN 21Z AND 00Z.
EXPECT MAINLY VFR CONDITIONS TONIGHT...HOWEVER THERE MAY BE A
LINGERING -SHSN AT JHW LATE.
OUTLOOK...
SATURDAY...MAINLY VFR. A CHANCE OF SNOW SOUTH.
SUNDAY...VFR.
MONDAY AND TUESDAY...IFR/MVFR. RAIN OR SNOW LIKELY.
&&
.MARINE...
ALTHOUGH NORTHWESTERLY WINDS HAVE DIMINISHED...AN INCREASING
SOUTHWESTERLY FLOW WILL REQUIRE ADDITIONAL SMALL CRAFT HEADLINES
TODAY. WINDS WILL DIMINISH TONIGHT AS WINDS VEER TO THE
NORTHWEST...AND EVENTUALLY THE NORTHEAST ON SATURDAY.
A STRONG AREA OF LOW PRESSURE IS FORECAST TO LIFT ACROSS ONTARIO
PROVINCE ON TUESDAY. THIS WILL RESULT IN A BRISK FLOW ACROSS THE
WATERS...WITH WESTERLY WINDS POSSIBLY APPROACHING GALES ON TUESDAY
DEPENDING ON THE TRACK AND STRENGTH OF THE LOW.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LEZ040-
041.
SMALL CRAFT ADVISORY UNTIL 5 AM EDT SATURDAY FOR
LOZ043.
SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR
LOZ042.
SMALL CRAFT ADVISORY UNTIL 5 AM EDT SATURDAY FOR LOZ044-
045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...WOOD
AVIATION...APFFEL
MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
651 AM EDT FRI MAR 15 2013
.SYNOPSIS...
LOW PRESSURE TRACKING ACROSS SOUTHERN ONTARIO WILL BRING SOME SNOW
SHOWERS TO THE REGION TODAY...THEN ANOTHER LOW PASSING TO THE SOUTH
WILL CONTINUE THIS RISK FOR THE SOUTHERN TIER ON SATURDAY. ANY SNOW
ACCUMULATIONS WILL BE LIGHT...WITH A RETURN TO DRY WEATHER ON
SUNDAY. OTHERWISE...TEMPERATURES ARE EXPECTED TO REMAIN ON THE COOL
SIDE FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
A CLIPPER LOW EMBEDDED IN A NORTHWESTERLY FLOW AT 500 MB WILL DIVE
SOUTHWARD OUT OF CANADA AND INTO NORTHERN NEW YORK THIS
AFTERNOON. MOISTURE IS QUITE LIMITED WITH THIS SYSTEM...BUT THERE
IS AN AREA OF LIFT ASSOCIATED WITH WARM AIR ADVECTION IN THE MID-
LEVELS WHICH EXTENDS SOUTH OF THE LOW. MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT AN AREA OF LIGHT SNOW WILL SPREAD ACROSS WESTERN NEW YORK
DURING THE MORNING HOURS. 06Z RUNS OF THE NAM AND GFS AND SEVERAL RUNS
OF THE HRRR TREND SLIGHTLY NORTHWARD WITH QPF...AND A BIT HIGHER.
THE HIGHER QPFS APPEAR OVERDONE WHEN COMPARED WITH OBSERVED
CONDITIONS...BUT PLACEMENT TRENDS SEEM GOOD. WHILE CONFIDENCE IS
FAIRLY HIGH THAT SOME SNOW WILL FALL...ACCUMULATIONS IN WESTERN
NEW YORK WILL ALMOST CERTAINLY BE LIGHT. ALSO...THE MARCH SUN
ANGLE SHOULD LIMIT SNOW ACCUMULATIONS...WITH LIGHT SNOW PROBABLY
MAINLY ACCUMULATING ON GRASSY SURFACES. EXPECT LESS THAN AN INCH
IN MOST LOCATIONS...WITH PERHAPS AN INCH OR TWO ACROSS SLIGHTLY
HIGHER TERRAIN IN ERIE AND WYOMING COUNTIES...WHERE THE BEST LIFT
IS EXPECTED.
WITH THE LOW A FAIRLY VIGOROUS SHORTWAVE ALOFT WILL DIVE ACROSS
THE NORTH COUNTRY THIS AFTERNOON. 850 MB TEMPERATURES ARE COLD
ENOUGH THAT IN COMBINATION WITH THE SHORTWAVE THERE PROBABLY WILL
BE SOME LAKE ENHANCEMENT. BECAUSE OF THIS...SNOW SHOWERS MAY BE A
BIT MORE INTENSE BUT ALSO MORE HIT OR MISS. SO WHILE ACCUMULATIONS
WILL VARY...THESE SNOW SHOWERS WILL HAVE A GREATER POTENTIAL TO
LOCALIZED SNOW ACCUMULATIONS OF A COUPLE INCHES.
OTHERWISE...EXPECT ANOTHER CHILLY DAY...WITH HIGHS IN THE MID TO
UPPER 30S IN MOST LOCATIONS.
FOR TONIGHT...LOW PRESSURE WILL TRACK ALONG A STALLED FRONTAL
BOUNDARY...WHICH IS FORECAST TO STAY TO THE SOUTH OF OUR REGION.
THERE IS A CHANCE SOME SNOW SHOWERS WILL SNEAK INTO FAR SOUTHERN
PORTIONS OF THE SOUTHERN TIER. OTHERWISE...LINGERING SNOW SHOWERS
EAST OF LAKE ONTARIO SHOULD TAPER OFF AFTER MIDNIGHT. IN BOTH CASES
ANY SNOW ACCUMULATION WOULD BE NEGLIGIBLE...WITH DRY WEATHER
EXPECTED FOR THE VAST MAJORITY OF WESTERN NEW YORK TONIGHT. FAIRY
PERSISTENT CLOUD COVER SHOULD LIMIT RADIATIONAL COOLING
TONIGHT...WITH LOWS MAINLY IN THE LOWER TO MID 20S...UPPER TEENS EAST
OF LAKE ONTARIO.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
FOR THIS PERIOD LARGELY QUIET CONDITIONS THROUGH THE WEEKEND...AND
CONTINUED CHILLY.
SATURDAY MORNING A FRONTAL BOUNDARY WILL BE TO OUR SOUTH...JUST
SOUTH OF THE MASON-DIXON LINE. SEVERAL SURFACE WAVES RIDING ALONG
THIS FRONTAL BOUNDARY WILL BRING CHANCES FOR LIGHT SNOW ACROSS THE
SOUTHERN TIER. SOME OF THE COLDEST AIR (-32C) AT 850 HPA IN THE
NORTHERN HEMISPHERE WILL BE BUILDING SOUTHWARD TO NEAR JAMES BAY FOR
THE START OF THE WEEKEND. WHILE WE WILL NOT SEE 850 HPA TEMPERATURES
THIS LOW...HIGH PRESSURE ASSOCIATED WITH THIS COLD POOL WILL BRING A
CHILLY NORTHERLY FLOW FROM CANADA ACROSS THE REGION SATURDAY. THIS
FLOW WILL KEEP TEMPERATURES 10 DEGREES OR SO BELOW NORMAL THROUGH
THE DAY...AND WITH THE UPSLOPE FLOW SOUTH OF LAKE ONTARIO A PASSING
FLURRY IS POSSIBLE SOUTH OF LAKE ONTARIO.
SATURDAY NIGHT AND SUNDAY THIS HIGH PRESSURE FROM CANADA WILL BUILD
SOUTHWARD TOWARDS THE EASTERN GREAT LAKES REGION. MOISTURE LINGERING
IN THE LOWER LAYERS WILL LIKELY KEEP PARTLY CLOUDY SKIES THROUGH
SATURDAY NIGHT...THOUGH THINNING MOISTURE WILL ALLOW FOR INCREASING
AMOUNTS OF SUNSHINE ON SUNDAY. TEMPERATURES SATURDAY NIGHT AND
SUNDAY WILL STILL AVERAGE 5 TO 10 DEGREES BELOW MID MARCH NORMALS.
SUNDAY NIGHT SHOULD SEE MUCH OF THE AREA CLEARING OUT WITH AGAIN
COLD TEMPERATURES AS THE SURFACE HIGH NEARS THE REGION. WITH THE
LIGHT WINDS AND CLEAR SKIES GOOD RADIATIONAL COOLING CONDITIONS WILL
ALLOW TEMPERATURES TO DROP QUICKLY. OVERNIGHT LOWS WILL DROP INTO
THE TEENS...WITH A FEW LOW 20S ACROSS THE LAKE PLAIN. ACROSS THE
NORTH COUNTRY TEMPERATURES ARE EXPECTED TO DROP INTO THE LOW TEENS
UNDER CLEAR SKIES.
BY LATE SUNDAY NIGHT THE HIGH PRESSURE WILL BE SLIDING TO THE EAST
AND ALLOW FOR MOISTURE TO INCREASE FROM THE SOUTHWEST. THIS WILL
BRING INCREASING LATE TOWARDS SOUTHWESTERN NEW YORK. ANY
PRECIPITATION WILL LIKELY REMAIN JUST TO THE SOUTH AND WEST OF OUR
CWA.
AN UPPER LEVEL SHORTWAVE WILL BE CROSSING THE NORTH COUNTRY SUNDAY
NIGHT...BUT WITH LITTLE MOISTURE IN THE LOWER LEVELS AND THE
MOISTURE THAT IS MOVING INTO THE CWA REMAINING WELL TO THE SOUTH
EXPECT A DRY SUNDAY NIGHT HERE.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE MAIN FOCUS FOR THIS PERIOD CONTINUES TO BE ON THE DEVELOPMENT OF
A LARGE STORM SYSTEM OVER THE NATION/S MID-SECTION SUNDAY
NIGHT...THE RESULT OF THE PHASING OF NORTHERN AND SOUTHERN STREAM
DISTURBANCES. MODELS ARE IN GOOD AGREEMENT ON THE BASIC PICTURE WITH
A LARGE LOW PRESSURE SYSTEM CONSOLIDATING OVER THE WESTERN GREAT
LAKES BY MONDAY EVENING. THIS WILL RESULT IN THE AFOREMENTIONED
BAROCLINIC ZONE BEING ADVECTED NORTHWARDS ACROSS WESTERN/CENTRAL NEW
YORK...BRINGING WARMING TEMPERATURES INTO THE MID TO UPPER 30S.
INCREASING SOUTHERLY/DOWNSLOPING WINDS MAY EVEN PUSH AREAS NEAR THE
LAKES INTO THE LOWER 40S MONDAY AFTERNOON. THE WARM UP WILL COME AT A
PRICE HOWEVER AS PRECIPITATION WILL ACCOMPANY THE WARM FRONTAL
PASSAGE. AT THIS POINT IT APPEARS THAT MOST AREAS SHOULD SEE A BRIEF
PERIOD OF SNOW AHEAD OF THE WARM FRONT FOLLOWED BY A RAPID
TRANSITION OVER TO RAIN AS THE LOW LEVELS WARM SIGNIFICANTLY. BY
MONDAY NIGHT MOST AREAS SHOULD BE SEEING RAIN...A POTENTIALLY QUITE
A BIT AT THAT WITH QPF RUNNING IN THE NEIGHBORHOOD OF ONE QUARTER TO
THREE QUARTERS OF AN INCH.
EXPECT A TRANSITION FROM RAIN BACK TO SNOW AGAIN TUESDAY AS THE LOW
PRESSURE SYSTEM TRACKS ACROSS THE UPPER SAINT LAWRENCE
VALLEY...MERGING WITH A SECONDARY COASTAL LOW OVER NEW ENGLAND AND
SWINGING A COLD FRONT ACROSS THE LOWER GREAT LAKES. THE COMBINATION
OF THE UPPER LEVEL TROUGH MOVING OVERHEAD AND THE INCREASING COLD
ADVECTION WILL MEAN WIDESPREAD SNOW SHOWERS ACROSS THE REGION
DEVELOPING TUESDAY AND LINGERING WELL INTO WEDNESDAY AS TEMPERATURES
DIP BACK BELOW NORMAL.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
CONDITIONS WILL REMAIN VFR THROUGH 12Z...WITH JUST A MID-LEVEL
CLOUD DECK. AFTER THIS...SOME LIGHT SNOW IS FORECAST TO DEVELOP
ACROSS THE REGION...WHICH WILL LIKELY RESULT IN ONLY MODESTLY
LOWER VSBY/CIGS AT SOME TAF SITES. THIS AREA WILL EXIT TO THE
SOUTH AND EAST TOWARD SUNSET...WITH MAINLY VFR CONDITIONS LIKELY DURING
THE EVENING HOURS.
OUTLOOK...
SATURDAY...MAINLY VFR. A CHANCE OF SNOW SOUTH.
SUNDAY...VFR.
MONDAY AND TUESDAY...IFR/MVFR. RAIN OR SNOW LIKELY.
&&
.MARINE...
ALTHOUGH NORTHWESTERLY WINDS HAVE DIMINISHED...AN INCREASING
SOUTHWESTERLY FLOW WILL REQUIRE ADDITIONAL SMALL CRAFT HEADLINES
TODAY. WINDS WILL DIMINISH TONIGHT AS WINDS VEER TO THE
NORTHWEST...AND EVENTUALLY THE NORTHEAST ON SATURDAY.
A STRONG AREA OF LOW PRESSURE IS FORECAST TO LIFT ACROSS ONTARIO
PROVINCE ON TUESDAY. THIS WILL RESULT IN A BRISK FLOW ACROSS THE
WATERS...WITH WESTERLY WINDS POSSIBLY APPROACHING GALES ON TUESDAY
DEPENDING ON THE TRACK AND STRENGTH OF THE LOW.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LEZ040-
041.
SMALL CRAFT ADVISORY UNTIL 5 AM EDT SATURDAY FOR
LOZ043.
SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR
LOZ042.
SMALL CRAFT ADVISORY UNTIL 5 AM EDT SATURDAY FOR LOZ044-
045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...WOOD
AVIATION...APFFEL
MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
258 AM EDT FRI MAR 15 2013
.SYNOPSIS...
HIGH PRESSURE OVER THE GULF COAST AND CARIBBEAN WILL INFLUENCE OUR
AREA UNTIL A COLD FRONT SETTLES SOUTH INTO THE CAROLINAS THIS
WEEKEND.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 10 PM THURSDAY...
TONIGHT:
AN UPPER LEVEL DISTURBANCE CURRENTLY OVER TN/KY IS EXPECTED TO MOVE
ACROSS THE REGION OVERNIGHT IN GENERAL WEST-NORTHWEST TO NORTHWEST
FLOW ALOFT... WITH THE BEST COMBINATION OF MOISTURE AND LIFT
EXPECTED TO REMAIN TO THE SOUTH AND WEST OF CENTRAL NC. WE WILL SEE
PERIODS OF PARTLY TO MOSTLY CLOUDY SKIES (MAINLY MID AND HIGH LEVEL
CLOUD COVER AND POSSIBLY ENHANCED AT TIMES BY OROGRAPHIC EFFECTS
FROM THE MOUNTAINS)THIS EVENING... IN ASSOCIATION WITH THE
DISTURBANCE THROUGH THE EARLY MORNING HOURS. THEN WE SHOULD SEE AN
OVERALL DECREASE IN THE CLOUD COVER BY 09Z... WITH POSSIBLY ONLY
SOME THIN HIGH CIRRUS IN THE FLOW ALOFT TRAVERSING THE AREA. NOT
EXPECTING ANY PRECIP WITH THE DISTURBANCE GIVEN THE DOWNSLOPE FLOW
AND ALREADY DRY AIRMASS IN PLACE. THUS... WILL CONTINUE A DRY
FORECAST. WRT LOW TEMPS... WILL LOWER TEMPS A BIT... AS WE SHOULD
SEE A PERIOD OF THINNER HIGH CLOUDS AND LESS COVERAGE BEHIND THE
EXITING DISTURBANCE. HOWEVER... WE WILL NEED TO KEEP AN EYE ON SOME
OROGRAPHIC ENHANCED CIRRUS POSSIBLY ON THE HEELS OF THE
AFOREMENTIONED DISTURBANCE... AS WATER VAPOR IMAGERY SHOWS
ADDITIONAL MOISTURE UPSTREAM OF THE DISTURBANCE. CONFIDENCE IN HOW
MUCH OF AN ENHANCEMENT OF THE CIRRUS WE WILL SEE FROM THE MOUNTAINS
IS STILL A BIT IN QUESTION... AND HOW MUCH IT WILL AFFECT THE LOW
TEMPS (DEPENDENT ON AMOUNT AND TIMING BOTH). FOR NOW WILL GO WITH
LOWS RANGING FROM THE UPPER 20S TO LOWER 30S ACROSS THE AREA... WITH
SOME OF THE USUAL RURAL COLD LOCATIONS ACROSS THE NORTH/NORTHEAST
(WHERE CLOUDS SHOULD BE THE LEAST) POSSIBLY FALLING INTO THE MID
20S. -BSD
FOR FRIDAY/FRIDAY NIGHT: THE NAM/GFS INDICATE A SHOT OF SHALLOW AND
MARGINALLY MOIST UPGLIDE AROUND 290K FRIDAY... SUGGESTIVE OF AREAS
OF STRATOCU THROUGH THE DAY... ALTHOUGH THE LATTER HOURS OF THE
LATEST RAP RUNS SHOW LESS IN THE WAY OF CLOUDS... AND THE NAM
DEPICTS LESS MOISTURE THAN THE GFS. EXPECT SKIES TO BE PARTLY CLOUDY
FOR MUCH OF THE DAY PARTICULARLY IN THE NORTH WHERE THE UPGLIDE
ITSELF IS STRONGER... ALTHOUGH PERIODS OF MOSTLY SUNNY SKIES ARE
EXPECTED ESPECIALLY IN THE SOUTH DURING THE EARLY TO MID AFTERNOON.
THE MODEL-PROJECTED LOW LEVEL THERMAL STRUCTURE SUPPORTS AN UPWARD
NUDGE TO FORECAST HIGHS... TO 61-67 WITH THE ONSET OF LOW LEVEL WARM
AIR ADVECTION AS WINDS BECOME SOUTHWESTERLY. MID AND HIGH CLOUDS NOW
OVER THE INTERIOR PACIFIC NORTHWEST ASSOCIATED WITH THE SURFACE
FRONTAL SYSTEM ARE EXPECTED TO OVERSPREAD THE REGION FROM MID-LATE
FRIDAY AFTERNOON THROUGH FRIDAY NIGHT. WHILE THE LOW LEVELS ARE
LIKELY TO DECOUPLE WITH AN INCOMING 45-50 KT WRLY 850 MB JET MOVING
IN FROM THE WEST... I SUSPECT THAT FORECAST SOUNDINGS ARE SHOWING
SURFACE TEMPS THAT ARE TOO COOL BASED ON A STEADY SW BREEZE...
TIGHTENING MSLP GRADIENT... AND THE INCREASE AND THICKENING OF
CLOUDS. HAVE BROUGHT UP LOW TEMPS FRIDAY NIGHT TO 43-50... A BIT
ABOVE STATISTICAL GUIDANCE. -GIH
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
AS OF 230 AM FRIDAY...
THERE IS STILL A GOOD BIT OF AGREEMENT BETWEEN THE 00Z GFS AND THE
12Z ECMWF WITH REGARD TO WHERE THE BACKDOOR FRONT WILL STALL AND THE
LOCATION OF THE PRECIP AXIS. BEST RAINFALL CHANCES WILL BE MAINLY
ALONG THE NC/VA BORDER SUNDAY MORNING AND SLOWLY PROGRESS SOUTHWARD
THROUGH SUNDAY NIGHT. HIGH TEMPS SUNDAY WILL DEPEND ON WHERE THE
FRONT SETTLES...BUT REGARDLESS WILL BE A SIGNIFICANT GRADIENT ACROSS
THE AREA...LOW 50S NE TO NEAR 70 SW. A 1028MB H85 HIGH PRESSURE IS
EXPECTED TO MOVE SOUTH AND EAST THROUGH CANADA AND INTO NEW
ENGLAND...WITH THE ASSOCIATED RIDGE AXIS EXTENDING SOUTHEAST INTO VA
AND CENTRAL NC. COMBINED WITH THE CHANCE FOR SOME LIGHT RAINFALL
ACROSS THE NORTHERN TIER OF THE AREA...A HYBRID CAD EVENT IS LIKELY
TO DEVELOP ACROSS THE NORTH/NORTHWEST SUNDAY NIGHT AND MONDAY. AS
THE CAD WEDGE DEVELOPS SUNDAY NIGHT...WILL SEE TEMPS FALL INTO THE
LOW 40S ACROSS THE NORTH WITH MID TO UPPER 40S ACROSS THE SOUTH.
ALTHOUGH THE CHANCE FOR CAD TO DEVELOP IS GOOD...THE STRENGTH...
EXTENT...AND DURATION OF THE WEDGE IS MAKING FOR A DIFFICULT
TEMPERATURE FORECAST FOR MONDAY. TEMPS ACROSS THE AREA WILL DEPEND
ON HOW STRONG THE CAD IS AND HOW FAR NORTH THE WARM FRONT IS ABLE TO
RETREAT BEFORE THE PRE-FRONTAL PRECIP MOVES IN FROM THE WEST. AS OF
RIGHT NOW...EXPECT THE WEDGE AIRMASS ACROSS THE NORTHWEST TO LINGER
THROUGH PEAK HEATING MONDAY...WHILE IT SHOULD ERODE ACROSS THE
SOUTH. AS SUCH...COULD SEE TEMPS IN THE LOW TO MID 50S ACROSS THE
NORTH...WHILE HIGHS ACROSS THE SOUTH COULD REACH 70 DEGREES...
HOWEVER CONFIDENCE IN THESE TEMPS IS SOMEWHAT LOW AT THIS TIME.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 356 AM FRIDAY...
MONDAY NIGHT THROUGH TUESDAY NIGHT:
A COLD FRONT WILL APPROACH FROM THE WEST MONDAY...WITH PRE FRONTAL
RAINFALL EXPECTED TO BEGIN CROSSING THE AREA MONDAY AFTERNOON.
THOUGH THE 12Z ECMWF AND 00Z GFS DIFFER IN REGARD TO THE AMOUNT OF
RAINFALL EXPECTED...BOTH MODELS AGREE THAT THE FRONT SHOULD PASS
THROUGH CENTRAL NC COMPLETELY BETWEEN 18Z TUESDAY AND 00Z WEDNESDAY.
AHEAD OF THE FRONT...LATE MONDAY NIGHT/EARLY TUESDAY MORNING THE GFS
FORECAST SOUNDINGS INDICATE THE POSSIBILITY OF SOME ELEVATED
CONVECTION...WITH LITTLE CIN AND MUCAPE AROUND 1000 J/KG. COMBINED
WITH DESCENT LAPSE RATES AND SHEAR...WILL INTRODUCE A SLIGHT CHANCE
OF THUNDER OUT AHEAD OF THE FRONT. EXPECT HIGH TEMPS ON TUESDAY IN
THE MID 50S TO MID 60S. SKIES SHOULD CLEAR OUT BEHIND THE FRONT...
AND WITH THE COLD AIR ADVECTING IN BEHIND IT...EXPECT LOWS TUESDAY
NIGHT IN THE MID TO UPPER 30S.
WEDNESDAY AND THURSDAY:
MODEL SOLUTIONS REALLY START TO DEVIATE FROM ONE ANOTHER ON
WEDNESDAY AND CONFIDENCE IS FAIRLY LOW FOR THIS PART OF THE FORECAST
AT THIS TIME. IN GENERAL EXPECT HIGH TEMPS IN THE MID 50S TO NEAR 60
DEGREES AND LOWS WEDNESDAY NIGHT IN THE MID 30S TO NEAR 40.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AS OF 245 AM FRIDAY...
UNDER THE INFLUENCE OF HIGH PRESSURE CENTERED OVER THE GULF COAST
REGION...VFR CONDITIONS WILL CONTINUE THROUGH TONIGHT. LIGHT
WESTERLY WINDS THIS MORNING WILL BACK TO SOUTHWESTERLY AND INCREASE
INTO THE 10-15 KT RANGE WITH GUSTS AROUND 20 KTS BY EARLY AFTERNOON.
THE POTENTIAL STILL EXISTS FOR LOW LEVEL WIND SHEAR TONIGHT...AS
WINDS WITHIN A STRENGTHENING INVERSION JUST ABOVE THE SURFACE --
AROUND 2000 FT -- INCREASE TO 40-45 KTS AT KFAY/KRWI/KRDU (WITH
WEAKER WINDS AT TRIAD TERMINALS). IT REMAINS UNCLEAR...HOWEVER...IF
THE BREEZY SOUTHWEST FLOW TODAY WILL INDEED SUBSIDE/BECOME LIGHT
ENOUGH (AT AROUND 5 KTS OR LESS) TO ALLOW SAID LLWS TO DEVELOP...OR
IF MECHANICAL TURBULENCE WILL INSTEAD DOMINATE.
OUTLOOK: A BACKDOOR COLD FRONT WILL SETTLE INTO CENTRAL NC SAT
NIGHT-SUN. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
DEVELOP IMMEDIATELY AHEAD OF THE FRONT LATE SAT AFTERNOON...MAINLY
JUST NORTH OF CENTRAL NC TERMINALS - IN THE VICINITY OF THE VA
BORDER. THE DEVELOPMENT OF SUB-VFR CONDITIONS AND A CHANCE OF RAIN
AND/OR DRIZZLE IN PROBABLE COLD AIR DAMMING AREA-WIDE (BUT FAVORED
AT NORTHERN TERMINALS) CAN BE EXPECTED SUNDAY-MONDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MWS
NEAR TERM...BSD/HARTFIELD
SHORT TERM..KC
LONG TERM...KC
AVIATION...MWS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
250 AM EDT FRI MAR 15 2013
.SYNOPSIS...
HIGH PRESSURE OVER THE GULF COAST AND CARIBBEAN WILL INFLUENCE OUR
AREA UNTIL A COLD FRONT SETTLES SOUTH INTO THE CAROLINAS THIS
WEEKEND.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 10 PM THURSDAY...
TONIGHT:
AN UPPER LEVEL DISTURBANCE CURRENTLY OVER TN/KY IS EXPECTED TO MOVE
ACROSS THE REGION OVERNIGHT IN GENERAL WEST-NORTHWEST TO NORTHWEST
FLOW ALOFT... WITH THE BEST COMBINATION OF MOISTURE AND LIFT
EXPECTED TO REMAIN TO THE SOUTH AND WEST OF CENTRAL NC. WE WILL SEE
PERIODS OF PARTLY TO MOSTLY CLOUDY SKIES (MAINLY MID AND HIGH LEVEL
CLOUD COVER AND POSSIBLY ENHANCED AT TIMES BY OROGRAPHIC EFFECTS
FROM THE MOUNTAINS)THIS EVENING... IN ASSOCIATION WITH THE
DISTURBANCE THROUGH THE EARLY MORNING HOURS. THEN WE SHOULD SEE AN
OVERALL DECREASE IN THE CLOUD COVER BY 09Z... WITH POSSIBLY ONLY
SOME THIN HIGH CIRRUS IN THE FLOW ALOFT TRAVERSING THE AREA. NOT
EXPECTING ANY PRECIP WITH THE DISTURBANCE GIVEN THE DOWNSLOPE FLOW
AND ALREADY DRY AIRMASS IN PLACE. THUS... WILL CONTINUE A DRY
FORECAST. WRT LOW TEMPS... WILL LOWER TEMPS A BIT... AS WE SHOULD
SEE A PERIOD OF THINNER HIGH CLOUDS AND LESS COVERAGE BEHIND THE
EXITING DISTURBANCE. HOWEVER... WE WILL NEED TO KEEP AN EYE ON SOME
OROGRAPHIC ENHANCED CIRRUS POSSIBLY ON THE HEELS OF THE
AFOREMENTIONED DISTURBANCE... AS WATER VAPOR IMAGERY SHOWS
ADDITIONAL MOISTURE UPSTREAM OF THE DISTURBANCE. CONFIDENCE IN HOW
MUCH OF AN ENHANCEMENT OF THE CIRRUS WE WILL SEE FROM THE MOUNTAINS
IS STILL A BIT IN QUESTION... AND HOW MUCH IT WILL AFFECT THE LOW
TEMPS (DEPENDENT ON AMOUNT AND TIMING BOTH). FOR NOW WILL GO WITH
LOWS RANGING FROM THE UPPER 20S TO LOWER 30S ACROSS THE AREA... WITH
SOME OF THE USUAL RURAL COLD LOCATIONS ACROSS THE NORTH/NORTHEAST
(WHERE CLOUDS SHOULD BE THE LEAST) POSSIBLY FALLING INTO THE MID
20S. -BSD
FOR FRIDAY/FRIDAY NIGHT: THE NAM/GFS INDICATE A SHOT OF SHALLOW AND
MARGINALLY MOIST UPGLIDE AROUND 290K FRIDAY... SUGGESTIVE OF AREAS
OF STRATOCU THROUGH THE DAY... ALTHOUGH THE LATTER HOURS OF THE
LATEST RAP RUNS SHOW LESS IN THE WAY OF CLOUDS... AND THE NAM
DEPICTS LESS MOISTURE THAN THE GFS. EXPECT SKIES TO BE PARTLY CLOUDY
FOR MUCH OF THE DAY PARTICULARLY IN THE NORTH WHERE THE UPGLIDE
ITSELF IS STRONGER... ALTHOUGH PERIODS OF MOSTLY SUNNY SKIES ARE
EXPECTED ESPECIALLY IN THE SOUTH DURING THE EARLY TO MID AFTERNOON.
THE MODEL-PROJECTED LOW LEVEL THERMAL STRUCTURE SUPPORTS AN UPWARD
NUDGE TO FORECAST HIGHS... TO 61-67 WITH THE ONSET OF LOW LEVEL WARM
AIR ADVECTION AS WINDS BECOME SOUTHWESTERLY. MID AND HIGH CLOUDS NOW
OVER THE INTERIOR PACIFIC NORTHWEST ASSOCIATED WITH THE SURFACE
FRONTAL SYSTEM ARE EXPECTED TO OVERSPREAD THE REGION FROM MID-LATE
FRIDAY AFTERNOON THROUGH FRIDAY NIGHT. WHILE THE LOW LEVELS ARE
LIKELY TO DECOUPLE WITH AN INCOMING 45-50 KT WRLY 850 MB JET MOVING
IN FROM THE WEST... I SUSPECT THAT FORECAST SOUNDINGS ARE SHOWING
SURFACE TEMPS THAT ARE TOO COOL BASED ON A STEADY SW BREEZE...
TIGHTENING MSLP GRADIENT... AND THE INCREASE AND THICKENING OF
CLOUDS. HAVE BROUGHT UP LOW TEMPS FRIDAY NIGHT TO 43-50... A BIT
ABOVE STATISTICAL GUIDANCE. -GIH
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 245 PM THURSDAY...
SATURDAY INTO SUNDAY...MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT
FOR SATURDAY THROUGH EARLY SUNDAY...DRIFTING A SFC COLD FRONT SWD
INTO CENTRAL NC BY SATURDAY NIGHT...THEN STALLING THIS FEATURE
ACROSS THE SOUTHERN COUNTIES ON SUNDAY. AHEAD OF THIS FEATURE ON
SATURDAY...EXPECT WARM CONDITIONS AS THICKNESSES PROJECTED TO BE IN
THE 1370S...30-35M ABOVE NORMAL. THIS IS SUPPORTIVE OF TEMPS IN THE
70S. RH CROSS SECTIONS SUGGEST THAT UPPER LEVEL MOISTURE MAY BE
PLENTIFUL ENOUGH TO PRODUCE AN OPAQUE VEIL OF HIGH CLOUDS...ENOUGH
TO LIMIT INSOLATION. IF FULL SUN CONDITIONS WERE TO OCCUR...COULD
EASILY SEE TEMPS IN THE 75-80 DEGREE RANGE. SINCE BANKING ON SOME
DEGREE OF CLOUDINESS...FAVOR MAX TEMPS MORE IN THE LOW-MID 70S.
THREAT OF CONVECTION WILL EXIST SATURDAY AFTERNOON AND SATURDAY
NIGHT AS SFC FRONT DRIFTS SWD TOWARD AND INTO THE REGION. BEST
PARAMETERS FOR T-STORMS WILL BE SATURDAY AFTERNOON AS MID LEVEL
LAPSE RATES PROJECTED TO BE AROUND 7 DEG C/KM WITH SFC BASED CAPE IN
THE 500-1000J/KG RANGE...MAINLY ACROSS THE NORTH. PROJECTED BULK
SHEAR VALUES NOT TOO SHABBY WITH VALUES RANGING FROM 35-55KTS. THESE
PARAMETERS SUGGEST POTENTIAL FOR A FEW STRONG T-STORMS BUT LACK OF
LOW LEVEL INSTABILITY SHOULD LIMIT SEVERITY. WILL NEED TO MONITOR
LOW LEVEL CONDITIONS LEADING UP TO SATURDAY AFTERNOON-EVENING.
FOR SUNDAY...NOW APPEARS A LITTLE MORE LIKELY THAT A WEAK HYBRID
DAMMING EVENT MAY OCCUR ACROSS THE NORTH AS A WEAK, NARROW DRY AIR
RIDGE EXTENDS INTO THE NORTHERN COUNTIES. MEANWHILE SSW FLOW ALOFT
WILL SPREAD MOISTURE UP OVER THE STALLED FRONT ACROSS THE
SOUTH...SETTING UP THE POSSIBILITY OF AREAS OF LIGHT RAIN/DRIZZLE
ACROSS THE NORTH LATE SUNDAY INTO SUNDAY NIGHT. NONETHELESS...SHOULD
SEE A WIDE TEMP VARIANCE ACROSS THE FORECAST AREA WITH TEMPS NEAR
AND SOUTH OF THE BOUNDARY NEAR 70...WHILE TEMPS IN THE FAVORED
DAMMING REGION MAY HOLD IN THE 50S.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 245 PM THURSDAY...
MONDAY...WILL LIKELY SEE A CONTINUANCE OF A WEAK CAD OR RESIDUAL CAD
AIR MASS OVER THE NORTHERN PIEDMONT AS STALLED BOUNDARY....DUE TO
LACK OF A MECHANISM TO PUSH BOUNDARY NWD UNTIL LATE...WILL LINGER
OVER THE SOUTH HALF OF THE FORECAST AREA. WILL STILL SEE A THREAT OF
RAIN ALONG AND NORTH OF THE BOUNDARY THOUGH APPEARS PRECIP WILL BE
SPARSE AND LIGHT IN INTENSITY. CLOUDS AND A COOL E-NE SFC FLOW WILL
KEEP TEMPS BELOW NORMAL ACROSS THE NORTH. MEANWHILE S-SW FLOW OVER
THE FAR SOUTH WILL RESULT IN ANOTHER DAY OF MILD TEMPS. MAX TEMPS
55-60 NORTH...NEAR 70 SOUTH.
MONDAY NIGHT AND TUESDAY...A SFC COLD FRONT ASSOCIATED WITH A S/W
TROUGH CROSSING THE GREAT LAKES WILL ADVANCE TOWARD CENTRAL NC
MONDAY NIGHT...AND CROSS THE PIEDMONT PRIOR TO DAYBREAK
TUESDAY...EXITING OUR COASTAL PLAIN COUNTIES PRIOR TO NOON. BEST MID
LEVEL CONFLUENCE AND UPPER LEVEL LIFT/SUPPORT OCCUR NORTH OF CENTRAL
NC. APPEARS THAT A RELATIVELY NARROW BAND OF SHOWERS WILL OCCUR
ALONG/AHEAD OF THE FRONT WITH RAPID DRYING/CLEARING OCCURRING
IMMEDIATELY BEHIND THE FRONT. THUS...APPEARS BEST CHANCE FOR RAIN
WILL OCCUR ACROSS THE WEST BETWEEN 06-12Z TUE...AND 09Z-15Z IN THE
EAST. STRONG CAA BEHIND FRONT BUT DOWNSLOPE COMPONENT TO LOW LEVEL
FLOW WILL OFFSET THE INITIAL SURGE OF COLD AIR. EXPECT MAX TEMPS
UPPER 50S NW TO LOW-MID 60S SE.
WEDNESDAY-THURSDAY...SENSIBLE WEATHER WILL BE DICTATED BY STRENGTH
OF UPPER TROUGH OVER THE NE U.S.. ECMWF DEEPER WITH THIS TROUGH WITH
THE PARENT LOW OVER SOUTHERN NEW ENGLAND. GFS NOT AS DEEP AND HAS
PARENT LOW FARTHER NORTH...OVER THE CANADIAN MARITIME. GFS ALLOWS
MINOR S/W RIDGE TO BUILD INTO THE SE U.S. RESULTING IN MILDER TEMPS
(COMPARED TO THE COLDER ECMWF). IT APPEARS THAT THE GFS IS TOO
PROGRESSIVE WITH THE UPSTREAM UPPER TROUGH MAKING ITS WAYS INTO THE
PACIFIC NW. THUS...WILL LEAN MORE TOWARD THE COLDER ECMWF SOLUTION.
VORTICITY MAXIMUM EMBEDDED IN THE NW FLOW ALOFT MAY CAUSE A PERIOD
OF CLOUDINESS THIS PERIOD BUT LACK OF MOISTURE FEED INTO THE REGION
SUGGEST LITTLE IF ANY CHANCES FOR APPRECIABLE PRECIPITATION.
EXISTENCE OF DEEP TROUGH SUGGEST TEMPS WELL BELOW NORMAL FOR MID
MARCH WITH AFTERNOON MAX TEMPS POSSIBLY AS MUCH AS 10-15 DEGREES
BELOW NORMAL (40S TO LOWER 50S). DO NOT PLAN TO GO THAT EXTREME THIS
FAR OUT. FAVOR MAX TEMPS 4-7 DEGREES BELOW NORMAL WED...AND 3-5
DEGREES BELOW THU.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AS OF 245 AM FRIDAY...
UNDER THE INFLUENCE OF HIGH PRESSURE CENTERED OVER THE GULF COAST
REGION...VFR CONDITIONS WILL CONTINUE THROUGH TONIGHT. LIGHT
WESTERLY WINDS THIS MORNING WILL BACK TO SOUTHWESTERLY AND INCREASE
INTO THE 10-15 KT RANGE WITH GUSTS AROUND 20 KTS BY EARLY AFTERNOON.
THE POTENTIAL STILL EXISTS FOR LOW LEVEL WIND SHEAR TONIGHT...AS
WINDS WITHIN A STRENGTHENING INVERSION JUST ABOVE THE SURFACE --
AROUND 2000 FT -- INCREASE TO 40-45 KTS AT KFAY/KRWI/KRDU (WITH
WEAKER WINDS AT TRIAD TERMINALS). IT REMAINS UNCLEAR...HOWEVER...IF
THE BREEZY SOUTHWEST FLOW TODAY WILL INDEED SUBSIDE/BECOME LIGHT
ENOUGH (AT AROUND 5 KTS OR LESS) TO ALLOW SAID LLWS TO DEVELOP...OR
IF MECHANICAL TURBULENCE WILL INSTEAD DOMINATE.
OUTLOOK: A BACKDOOR COLD FRONT WILL SETTLE INTO CENTRAL NC SAT
NIGHT-SUN. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
DEVELOP IMMEDIATELY AHEAD OF THE FRONT LATE SAT AFTERNOON...MAINLY
JUST NORTH OF CENTRAL NC TERMINALS - IN THE VICINITY OF THE VA
BORDER. THE DEVELOPMENT OF SUB-VFR CONDITIONS AND A CHANCE OF RAIN
AND/OR DRIZZLE IN PROBABLE COLD AIR DAMMING AREA-WIDE (BUT FAVORED
AT NORTHERN TERMINALS) CAN BE EXPECTED SUNDAY-MONDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MWS
NEAR TERM...BSD/HARTFIELD
SHORT TERM..WSS
LONG TERM...WSS
AVIATION...MWS
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
753 PM EDT SAT MAR 16 2013
.SYNOPSIS...
COLD FRONT SLOWLY CROSSES THIS EVENING BUT RETURNS NORTH SUNDAY AND
STALLS NEAR THE REGION. WAVE MOVES ALONG THE FRONT MONDAY. COLD
FRONT MONDAY NIGHT. COLDER TUESDAY.
&&
.NEAR TERM /THROUGH SUNDAY/...
EARLIER FCST THINKING GENERALLY ON TRACK. COVERAGE OF SHRA
INCREASING AS EXPECTED ACROSS WESTERN LOWLANDS AS OF 18Z. THIS
SHOULD CONT TO DEVELOP NEXT FEW HRS AS IT HEADS S WITH COLD FRONT.
SHOULD BEGIN TO SEE SOME CONVECTION AS WELL. DESPITE MEAGER
MOISTURE INFLUX...SOME SFC INSTABILITY REALIZED THIS AFTN ALONG
AND S OF I64 CORRIDOR WHERE SFC TEMPS HAVE CLIMBED INTO THE UPR
60S TO LWR 70S. RAP DEPICTS SFC CAPE GENERALLY 300 TO 500 J/KG
ACROSS SAID AREA. LLVL INVERTED V SOUNDINGS CONT TO SUGGEST SOME
WIND CONCERNS AS WELL. HAVE BEEN SEEING GENERAL 20 TO 25 KTS IN
GUSTS WITHOUT ANY SHRA/TSRA. LOW FZ LVLS MAY RESULT IN SOME HAIL
AS WELL FOR ANY DEEPER CONVECTION.
ALL OF THIS EXITS SW VA AND SE OH BY 00Z WITH FROPA. IMPRESSIVE
CAA THIS EVE WILL MAKE THIS AFTNS 70 DEGREE WX ACROSS PORTIONS OF
AREA...SEEM LIKE A DISTANT MEMORY.
THIS MARKS A TRANSITION BACK TO WINTER HEADING THRU TOMORROW AND
THE NEXT FCST HEADACHE. FRONT WILL BEGIN RETURNING N AS A WARM
DURING THE DAY WITH IMPRESSIVE ISENTROPIC LIFT ALLOW PCPN TO BREAK
OUT ALONG BOUNDARY. MOST OF MDLS ARE IN AGREEMENT WITH THE
POSITION OF THIS BOUNDARY DURING THE DAY...MAKING IT TO I64
CORRIDOR BY 21Z TO NEAR ATH-PKB-W22 BY 00Z. ALL OF THIS LEADS TO
PCPN CONUNDRUMS. DESPITE H85 TEMPS MARGINAL...LIFT IS DEEP ENOUGH
FOR SNOW SOUNDINGS N OF BOUNDARY...PROVIDED SFC TEMPS COOPERATE.
THINK SOME OF THE GUIDANCE NUMBERS ARE TOO HIGH FOR TOMORROW. WILL
HEDGE TOWARD COLDER MET DURING THE DAY WHICH APPEARS TO CAPTURE
WETBULBING DOWN TOWARD LWR 30S. THIS ALLOWS FOR A MIX ALONG I64
CORRIDOR WITH WET SN ON THE HILLS...TRANSITIONING TO MOSTLY SN N
OF I64. WILL KEEP ACCUM DOWN FOR NOW GIVEN TIME OF YEAR...WARM DAY
TDY...AND TIMING OF PCPN IN AFTN. DID CODE UP SOME COATINGS ON THE
HILLS WITH GENERAL 2 TO 3 INCHES IN N MTNS. COULD SEE SOME
COATINGS TOWARD VALLEY FLOORS IF PCPN COMES DOWN HARD ENOUGH. WILL
HOLD OFF ON ANY HEADLINES AFTER COORDINATING WITH SHORT TERM
FCSTER AND SURROUNDING OFFICES. TOO MUCH UNCERTAINTY ATTM GIVEN
SENSITIVE NATURE TO LOCATION OF BOUNDARY AND SFC TEMPS.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
MODELS HAVE BECOME VERY INTERESTING FOR SUNDAY AFTERNOON THROUGH
MONDAY MORNING. THIS WILL DEPEND ULTIMATELY ON HOW FAR SOUTH THE
COLD FRONT MAKES IT...ESPECIALLY THE COLD AIR NORTH OF THE FRONT.
MODELS ARE CURRENTLY INSISTING ON A BAND OF SNOW ACROSS SOUTHEAST
OHIO AND NORTHERN WEST VIRGINIA. WITH MODELS CHANGING CONSIDERABLY
FROM PREVIOUS RUNS AND SNOW BAND EXPECTED TO BE FAIRLY NARROW...WILL
HOLD OFF ON HEADLINES FOR THE MOMENT. SOUTHEAST UPSLOPE COULD ALSO
BE A CRITICAL FACTOR WITH ICING NOT OUT OF THE QUESTION.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
OVERALL...PATTERN NOT CHANGING MUCH AND STILL EXPECT COOLER THAN
NORMAL CONDITIONS IN THE WAKE OF THE STRONG COLD FRONT MONDAY
NIGHT. BIGGEST QUESTION OF THE FORECAST REMAINS THE COLD POOL LOW
LEVEL STRATUS DECK AND POTENTIAL FOR PRECIPITATION...BOTH LOWLANDS
AND THE MOUNTAINS. TRIED TO GO WITH MORE OF A CONSENSUS IN THE
OPERATIONAL GFS AND ECMWF MODELS IN TERMS OF ADDING
PRECIPITATION...BUT KEEP THE BULK OF ANY WEATHER REQUIRING AMOUNTS
IN THE SLIGHT CHANCE RANGE TO LOW END CHANCE.
WILL STRUGGLE TO SEE ANY LOWLAND TEMPERATURES CLIMB ABOVE 50F OVER
THE DURATION...WITH THE HIGHEST MOUNTAINS IN THE NORTHEAST
STRUGGLING TO GET ABOVE FREEZING AT THE HIGHEST
ELEVATIONS...INCLUDING SNOWSHOE. CONTINUE TO CARRY OVERNIGHT LOWS
AREA WIDE DROPPING BELOW FREEZING THROUGH THE DURATION.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
00Z SUNDAY THRU 00Z MONDAY...
COLD FRONT WORKING SEWD INTO SERN WV AT 23Z. SCATTERED LINE OF
SHRA/TSTM WITH FRONT WILL EXIT CWA BY 02Z. LOOKING FOR POST FRONTAL MVFR
STRATUS TONIGHT MOST TAF SITES...WITH PERHAPS SOME IMPROVEMENT NRN
SITES LATE. WILL WATCH FOR BOUNDARY TO RETURN N AS WARM FRONT ON
SUNDAY. IMPRESSIVE LIFT WILL ALLOW PCPN TO BREAK OUT ALONG AND N OF
BOUNDARY IN THE FORM OF A MIX ACROSS THE CENTRAL LOWLANDS AND SOME
WET SN N MTNS. HAVE A MIX IN KCRW AND KHTS TAFS BY 18Z. GENERAL MVFR
CIGS AND IFR VSBY EXPECTED AFTERWARD DEPENDING ON PCPN TYPE.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z MONDAY...
FORECAST CONFIDENCE...MEDIUM.
ALTERNATE SCENARIOS: MVFR CEILINGS MAY VARY OVERNIGHT.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE SUN 03/17/13
UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11
EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07
CRW CONSISTENCY H H H M M H H H H M M H
HTS CONSISTENCY H H H M H H H M M H H H
BKW CONSISTENCY H H H H H H H M M L M M
EKN CONSISTENCY L M H H H L L L L L L L
PKB CONSISTENCY M M H H H H M M M H H H
CKB CONSISTENCY M M H H H M M M M M M M
AFTER 00Z MONDAY...
IFR POSSIBLE SUNDAY INTO MONDAY NIGHT IN PRECIP.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30/26
NEAR TERM...30
SHORT TERM...RPY
LONG TERM...26
AVIATION...JMV
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
623 PM MDT SAT MAR 16 2013
.UPDATE...
ISSUED AT 600 PM MDT SAT MAR 16 2013
VIGOROUS LIFT ASSOCIATED WITH A ZIPPERING TROUGH ALONG A QUASI-
STATIONARY FGEN ZONE...HAS BEEN SUPPORTING HEAVY SNOWFALL ALONG
NARROW BAND OVER WEST CENTRAL SD. LATEST GUIDANCE SUGGEST
CONCENTRATED LIFT WILL CONTINUE ACROSS MAINLY
PENNINGTON/JACKSON/AND INTO MELLETTE COUNTIES THROUGH MUCH OF THIS
EVENING...WITH VERY EFFICIENT SNOW PRODUCTION GIVEN LIFT FOCUSED
IN THE DGZ. LOSS OF INSOLATION WITH FALLING TEMPS HAS SUPPORTED
ACCUMS ON ROADWAYS WITH BLACK ICE LIKELY GIVEN EARLIER SNOW MELT.
LATEST QPF GUIDANCE AND CURRENT RADAR/SAT ANALYSIS SUGGEST THAT
2-5 INCHES OF ADDITIONAL ACCUMS WILL POSSIBLE THROUGH THIS
EVENING...ESP WHERE BANDING PERSISTS. IN ADDITION...SATELLITE
ANALYSIS COUPLED WITH THE 00Z RAP RAOB INDICATED A POTENTIALLY
UNSTABLE ENVIRONMENT WITH LIKELY CONVECTIVE ENHANCEMENT OWING TO
1-2 INCHES AN HOUR SNOWFALL RATES INSIDE THE BAND. HAVE ISSUED A
WINTER WEATHER ADV.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 226 PM MDT SAT MAR 16 2013
UPPER LEVEL ANALYSIS HAS ZONAL FLOW OVER THE NORTHERN PLAINS WITH
WEAK SHORTWAVE CROSSING SOUTHEASTERN MONTANA AND NORTHEASTERN
WYOMING AT THE MOMENT. REGIONAL RADARS SHOWING A LIGHT TO MODERATE
BAND OF SNOW FROM THE CENTRAL AND SOUTHERN BLACK HILLS EXTENDING
EAST ONTO THE PLAINS. SEVERAL INCHES OF SNOW HAS FALLEN IN AREAS
WHERE THE HEAVIEST BANDS HAVE SET UP. AT THE SURFACE...ARCTIC HIGH
HAS SETTLED INTO NORTH DAKOTA WITH COOLER AIR BACKING INTO WESTERN
SOUTH DAKOTA. BROAD AREA OF STRATUS IN PLACE ACROSS SOUTHWESTERN
SOUTH DAKOTA AS WARMER/MOISTER AIR OVERRUNS THE COOLER AIR AT THE
SURFACE.
LATE THIS AFTERNOON AND TONIGHT...BAND OF SNOW EXTENDING FROM THE
BLACK HILLS EASTWARD WILL CONTINUE TO PRODUCE LIGHT TO MODERATE
SNOW FOR THE REMAINDER OF THE AFTERNOON AND EARLY EVENING. ONE TO
TWO ADDITIONAL INCHES OF SNOW WILL BE POSSIBLE...WITH SOME LOCALLY
HIGHER AMOUNTS. LIGHT SNOW WILL FINALLY SHIFT EAST LATER TONIGHT
AS MAIN SHORTWAVE MOVES OUT AND WEAK TRANSIENT RIDGE BUILDS IN.
FOR SUNDAY...STRONG/FAST MOVING SHORTWAVE TROUGH WILL MOVE FROM
WESTERN MT/ID TO MN BY 12Z MONDAY. SURFACE LOW WILL DEVELOP ALONG
THE MT/WY BORDER...MOVING INTO WESTERN SD BY 00Z...AND THEN
NORTHEAST MN BY 12Z MONDAY. IT WILL DRAG A STRONG COLD FRONT
THROUGH THE CWA SUNDAY AFTERNOON/EVENING. AHEAD OF THE FRONT 30KT+
SOUTHERLY JET DEVELOPS WHICH WILL PARTIALLY MIX TO THE GROUND BY
MIDDAY RESULTING IN WINDY SPOTS ACROSS SOUTH CENTRAL SOUTH DAKOTA.
40KT+ 850MB WEST TO NORTHWEST WINDS DEVELOP BEHIND THE COLD FRONT
AS IT SHIFTS EAST. CURRENT HIGH WIND WATCH FOR MUCH OF WESTERN
SOUTH DAKOTA LOOKS GOOD. OTHER IMPACT OF COLD FRONT AND STRONG
WINDS WILL BE LOWER VISIBILITIES WITH SNOW SHOWERS AFTER FRONTAL
PASSAGE. WINDS LOOK TO REMAIN FAIRLY STRONG INTO SUNDAY NIGHT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 226 PM MDT SAT MAR 16 2013
DEEP NORTHWESTERLY FLOW ALOFT IS EXPECTED ACROSS THE REGION FOR THE
FIRST HALF OF THE WORK WEEK. WEAK DISTURBANCES IN THE FLOW WILL
BRING AT LEAST SLIGHT CHANCES FOR SNOW SHOWERS ACROSS FAR
NORTHEASTERN WY...THE BLACK HILLS...AND PORTIONS OF NORTHWESTERN SD
MONDAY THROUGH TUESDAY. OTHERWISE...MAINLY DRY WEATHER IS EXPECTED
THROUGH WEDNESDAY. TEMPERATURES WILL BE A BIT TRICKY EARLY IN THE
WEEK WITH FRONTAL BOUNDARY IN PLACE OVER THE AREA. AM GENERALLY
EXPECTING A WARMING TREND ACROSS WESTERN AREAS THROUGH MIDWEEK...
WITH BELOW AVERAGE TEMPERATURES TO THE EAST OF THE BLACK HILLS. THE
NEXT SERIES OF WEATHER SYSTEMS WILL MOVE INTO THE REGION LATER
WEDNESDAY NIGHT AND THURSDAY. THE STRONGEST OF THESE DISTURBANCES
LOOKS LIKE IT WILL MOVE THROUGH THURSDAY INTO THURSDAY NIGHT. WILL
KEEP POP CHANCES ON THE HIGH SIDE FOR THESE PERIODS. LONG RANGE
MODELS ARE HAVING A HARD TIME HANDLING THE PATTERN BEYOND
FRIDAY...BUT THEY ARE LEANING TOWARD DRIER NORTHWESTERLY FLOW INTO
NEXT WEEKEND...SO WILL GO WITH DRY FORECAST FOR SATURDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 600 PM MDT SAT MAR 16 2013
MVFR/IFR CONDITIONS CAN BE EXPECTED ACROSS MUCH OF THE BLACK HILLS
AREA AND SOUTHWESTERN SD THROUGH MUCH OF THE EVENING...ESP WITH
THE BAND OF SNOW THAT CONTINUES TO SLOWLY MOVE EAST ACROSS THE
AREA. THIS BAND OF PCPN WILL CONTINUE TO MOVE INTO PORTIONS OF
SOUTH CENTRAL SD THIS EVENING AND EVENTUALLY DISSIPATE OVERNIGHT.
HOWEVER...MVFR/IFR CIGS WILL LIKELY PERSIST OR REDEVELOP ACROSS
MUCH OF THE FORECAST AREA OVERNIGHT /ESP OVER THE EASTERN BLACK
HILLS FOOTHILLS/ INTO SUNDAY MORNING AS SOUTH TO SOUTHEAST WINDS
CONTINUE. STRONG GUSTY WEST CAN BE EXPECTED SUNDAY AFTERNOON AS
STRONG COLD FRONT MOVES THROUGH THE AREA. SUSTAINED WINDS OF 25 TO
35 MPH WITH GUSTS OVER 60 WILL BE POSSIBLE...ESP AT KRAP.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...HIGH WIND WATCH FROM SUNDAY AFTERNOON THROUGH LATE SUNDAY NIGHT
FOR SDZ001-002-012-013-025-026-030-031-041>044-072>074.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT /1 AM CDT/ TONIGHT
FOR SDZ031-043-046.
WY...NONE.
&&
$$
UPDATE...JC
SHORT TERM...15
LONG TERM...26
AVIATION...JC
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
831 PM CDT SAT MAR 16 2013
.UPDATE...COLD FRONT HAS NOW PUSHED TO A LINE EXTENDING FROM
SOUTHWEST VIRGINIA...TO JUST NORTH OF CROSSVILLE...TO JUST NORTH
OF COLUMBIA AND JACKSON, TN. COOLER AIR AND LOWER DEW POINTS
SPREADING IN BEHIND FRONT AND EXPECT THIS TO CONTINUE FOR THE REST
OF THE NIGHT. LATEST RUC CONTINUES TO SHOW INCREASING 1000-700MB
MOISTURE BEHIND THE FRONT FOR THE REST OF THE NIGHT, WITH FRONT
NOT EXPECTED TO PUSH MUCH FURTHER SOUTH THAN IT ALREADY IS.
WILL UPDATE TO LOWER MIN TEMP EXPECTATIONS A BIT BEHIND COLD FRONT
TONIGHT, AND UPDATE GRIDS TO AGREE BETTER WITH CURRENT TRENDS.
SINCE FRONT IS NOT EXPECTED TO PUSH MUCH FURTHER SOUTH, BELIEVE
CURRENT POP/WX ARRANGEMENT FOR OVERNIGHT STILL LOOKS REASONABLE
(ESPECIALLY SINCE NOTHING IS SHOWING UP ON THE SCOPE IN OUR CWA AS
OF YET).
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
19
AREA FORECAST DISCUSSION
NWS SPOKANE WA
840 PM PDT Sat Mar 16 2013
.SYNOPSIS...
Breezy to windy conditions and colder temperatures will arrive
tonight as a cold front sweeps through the Inland Northwest. The
mountains will receive several inches of snow tonight into Sunday.
Breezy conditions will persist into Monday and the mountains will
continue to receive rain and snow showers. A break in the active
weather regime is expected on Tuesday before another strong storm
system brings wet and windy weather for Wednesday.
&&
.DISCUSSION...
Valley rain and mountain snow showers continue across the Inland
Northwest tonight. There were a few lightning strikes across the
upper Columbia Basin and the northeast zones as the cold front
moved through. There were a couple reports of small hail and gusty
winds with the thunderstorms. The convective showers will be
limited to extreme northeast WA and the northern panhandle of
Idaho through about 10 pm. There is still a slight chance of a
rumble or two of thunder with these showers but this will be very
localized and will be handled with NOWcasts. The focus for post
frontal snow showers will be on the Cascade Crest and the Puget
Sound convergence zone along with the north Idaho mts and NE
Blues. The HRRR has a pretty good handle on the precip so far,
including the Puget Sound Convergence Zone and the area of showers
headed for the NE Blue Mts. The afternoon forecast package was
leaning toward this model and remains in good shape. No big
changes for the evening update. /Kelch
&&
.AVIATION...
00Z TAFS: Showers will start to diminish after sunset. A few of
the stronger cells may contain some small hail or grauple along
with brief heavy downpours and gusty winds. Windy conditions will
accompany the passage of the cold front through eastern WA by 01Z
and through north ID by 03Z. Post frontal gusts will likely persist
through the night. Gusts of 30kts or more will be possible at
Pullman through the night with gusts of 22-27kt common at KGEG,
KSFF, KMWH and KEAT. Instability rain and snow showers will be
possible again Sunday afternoon. Gusty winds will continue through
00Z Mon. /EK
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 32 45 28 47 29 49 / 70 30 10 20 10 10
Coeur d`Alene 32 44 27 46 28 48 / 90 40 20 40 30 10
Pullman 30 43 28 46 30 50 / 70 30 20 20 10 20
Lewiston 36 50 33 53 34 57 / 40 30 10 10 10 10
Colville 33 48 29 51 28 55 / 50 30 10 20 10 10
Sandpoint 32 42 29 41 28 45 / 90 50 20 40 40 10
Kellogg 31 39 27 39 27 48 / 100 80 50 50 50 10
Moses Lake 35 52 32 56 31 56 / 20 10 0 0 10 30
Wenatchee 34 51 33 53 33 53 / 20 0 10 10 10 40
Omak 32 50 28 53 27 55 / 10 10 10 10 10 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
451 PM PDT Sat Mar 16 2013
.SYNOPSIS...
Breezy to windy conditions and colder temperatures will arrive
tonight as the front sweeps through the Inland Northwest. The
mountains will receive several inches of snow tonight into Sunday.
Breezy conditions will persist into Monday and the mountains will
continue to receive rain and snow showers. A break in the active
weather regime is expected on Tuesday before another strong storm
system brings wet and windy weather for Wednesday.
&&
.DISCUSSION...
Tonight and Sunday...
...Mountain snow and increasing winds tonight into Sunday...
A strong cold front passage will occur this evening bringing an
increase in winds...showers...as well as rapidly falling snow
levels with accumulating snow in the Cascades, Blues, and Central
Panhandle Mountains tonight into Sunday morning.
The air mass will continue to destabilize through the early
evening as 500mb temperatures drop to -30 to -33C which combined
with heating from the afternoon will steepen temperature lapse
rates. The GFS and NAM show the best instability generally north
of Interstate 90 with CAPES around 100-200 J/KG where a stray
lightning strike it not out of the question. Strong prefrontal
southwest winds of 20-30 knots at 850mb will result in strong
downslope flow off the Cascades which will limit precipitation
chances with this front for places like Omak, Wenatchee, and Moses
Lake. Behind the front moist...unstable northwest flow will favor
moderate to heavy snow showers in the Cascades impacting travel
along the stretch from Stevens Pass to Coles Corner. A Puget Sound
Convergence Zone is also likely to develop with the HRRR showing a
band of enhanced snow between 7 pm-11 pm in this area...also
impacting Plain and Leavenworth and possibly even as far east as
Wenatchee...with snow levels in the evening falling to near 2000
feet. The strong westerly flow behind the front will shadow out
most of Central and Eastern Washington overnight but snow showers
will redevelop over the Central Panhandle Mountains, Blues, and
possibly the Camas Prairie. This could also make travel difficult
over Lookout Pass overnight and Sunday morning. A cool and
unstable air mass behind the front will promote additional showers
Sunday afternoon...but the high sun angle will make afternoon
accumulations difficult and confined to brief periods under heavy
showers.
With the strong cold front passage 850mb winds will increase to
30-40 knots behind the front overnight. Soundings show a shallow
stable layer which should keep gusts mostly in the 20-30 mph
range. Although local gusts to 40 mph are possible. As mixing
increases on Sunday wind gusts for most valleys will increase to
35-45 mph however pressure gradients will be subsiding which
should keep most locations below advisory level winds. The
northern valleys will be more sheltered from the west winds. JW
Sunday night through Tuesday...The combination of an exiting
upper level trough moving east of the divide and high pressure
building in the eastern Pacific will keep a cool northwest flow
over the Pacific Northwest Sunday night through late Monday. A
series of weak disturbances in the northwest flow will keep some
mention of precipitation across the the eastern zones. The ridge
will track east and through the region Monday night and
Tuesday ahead of the next upstream weather system and result in a
drying trend.
Sunday night and Monday...The upper level flow will become
northwest Sunday night and Monday. The combination of a conditionally
unstable air mass...some weak short wave disturbances and orographic
flow into the Idaho Panhandle favors showers across the eastern
zones. The one ingredient that is lacking is a good moisture
source...which gets cut off from the main flow. In reality this
will just make showers a little more scattered and keep precipitation
amounts on the light side. Snow levels will be such that all
precipitation will be as snow or possibly a rain/snow mix in the
lower mountain valleys. Gusty southwest to west winds will remain
through the evening but are expected to decrease over night. Winds
will increase slightly on Monday but should be 5-10 mph less than
Sunday. Temperatures will remain on the cool side of normal.
Monday night and Tuesday...There are some timing differences in
the models through this period of the forecast and chose to lean
towards a solution that is just slightly faster than the ECMWF.
As the ridge ambles eastward the region will see a drying trend
overnight and early Tuesday. Clearing skies will result in a return
to chilly morning temperatures with lows on the a few degrees
below normal. By Tuesday afternoon the upper flow will back to
south-southwest and allow Pacific moisture to surge back into the
region. The southwest zones will have a chance to get some light
precipitation as warm front approaches. But this will just be the
early stages as the brunt of the moisture is expected Tuesday
night and Wednesday. /Tobin
Tuesday night through Thursday night: A vigorous shortwave trough
of low pressure will swing through the region around mid week.
This shortwave, moving southeast out of the Gulf of Alaska, will
scoop up a closed low pressure system between 140-150W Longitude
and 30-40N Latitude on Monday. The proximity of this closed low to
the sub-tropics will result in flux of very moist air toward the
Inland Northwest. A warm front will push in across the region from
the southwest on Tuesday night. This will result in widespread
stratiform type precip as the region remains in the warm sector of
the weather system through Wednesday. A strong cold front will
move into the Cascades around early Wednesday afternoon and then
spread eastward across the region through the day. Lift along the
cold front will likely enhance precip amounts, but should begin to
dry things out behind the front from west to east. Winds will also
be on the increase with strong cold air advection resulting in a
tightening of surface pressure gradients across the region.
Precipitation...
*Type: Temps at 850 mbs will start at around +3 to +5 Celsius
across southern WA to 0 to -1 Celsius further north along the
Canadian border. These temps will only increase with the warm
front through Tuesday night into Wednesday. This will result in
rising snow levels and valley rain and mountain snowfall. Wet
bulb affects will act to cool the lower portion of the atmosphere
a bit for Tuesday night. So there is still a bit of uncertainty
with snow level at this time, and we may start out as snow or a
rain/snow mix across the northern valleys.
*Amounts: Expect mainly light precip accumulations with the warm
front. Precip intensity will likely increase with the cold front
on Wednesday. Mid level lapse rates will likely become a bit more
unstable as the upper level trough approaches with cold front
passage. As a result, we should see more moderate precip rates
with the cold front. Post frontal showers will continue across the ID
Panhandle Wednesday night into Thursday with snow levels dropping
down to valley floors.
Winds...
We will see some gusty winds possible with the passage of the cold
front on Wednesday and Wednesday night. Best potential for strongest
winds will be in the afternoon and evening hours on Wednesday. We
should remain breezy through Wednesday night before pressure
gradients weaken substantially on Thursday.
Forecast Confidence...
Confidence is moderate at this time. There is relatively good
agreement with the models; however, there are still some subtle
differences. The NAM and SREF is considerably faster than the GFS
and ECMWF, so these solutions were largely ignored with the timing
of this system. /SVH
Friday through Saturday night...A difference in the extended
forecast as models are now less impressed with the upper level
ridge nosing into the Inland Northwest. A Gulf of Alaska low
pressure now looks to keep the ridge suppressed and offshore.
Shortwaves rotating around the low in northwest or west-northwest
flow will keep chances for precipitation going for the Cascades
and the rising terrain of northern Washington and the Idaho
panhandle. The previous forecast had this trend already, and this
was only adjusted slightly. Temperatures look to be right around
seasonal normals for both Friday and Saturday. ty
&&
.AVIATION...
00Z TAFS: Showers will start to diminish after sunset. A few of
the stronger cells may contain some small hail or grauple along
with brief heavy downpours and gusty winds. Windy conditions will
accompany the passage of the cold front through eastern WA by 01Z
and through north ID by 03Z. Post frontal gusts will likely persist
through the night. Gusts of 30kts or more will be possible at
Pullman through the night with gusts of 22-27kt common at KGEG,
KSFF, KMWH and KEAT. Instability rain and snow showers will be
possible again Sunday afternoon. Gusty winds will continue through
00Z Mon. /EK
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 32 45 28 47 29 49 / 70 30 10 20 10 10
Coeur d`Alene 31 44 27 46 28 48 / 90 40 20 40 30 10
Pullman 30 43 28 46 30 50 / 70 30 20 20 10 20
Lewiston 36 50 33 53 34 57 / 40 30 10 10 10 10
Colville 32 48 29 51 28 55 / 50 30 10 20 10 10
Sandpoint 32 42 29 41 28 45 / 90 50 20 40 40 10
Kellogg 29 39 27 39 27 48 / 100 80 50 50 50 10
Moses Lake 36 52 32 56 31 56 / 20 10 0 0 10 30
Wenatchee 35 51 33 53 33 53 / 20 0 10 10 10 40
Omak 30 50 28 53 27 55 / 10 10 10 10 10 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1013 PM CDT SAT MAR 16 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND SUNDAY.
THE LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW THIS
MORNINGS LIGHT SNOW DIMINISHING AS IT MOVES SOUTH OVER SOUTHERN
WISCONSIN. AFTER A BRIEF MOMENT OF CLEARING...WEST WINDS HAVE
BROUGHT IN ADDITIONAL CLOUD COVER ACROSS MUCH OF NORTHERN WISCONSIN
AND THE UPPER PENINSULA. LOOKING UPSTREAM...A STRONG SHORTWAVE IS
DIVING TO THE SOUTH ALONG THE MANITOBA/ONTARIO BORDER. SNOW SHOWERS
FROM THIS WAVE ARE MAKING IT TO THE NORTHERN MANITOBA BORDER EARLY
THIS AFTERNOON. SNOW SHOWER POTENTIAL FROM THIS WAVE AND
TEMPERATURES ARE THE MAIN FORECAST CONCERNS.
TONIGHT...A STRONG SHORTWAVE WILL SWING SE ACROSS THE SOUTHERN HALF
OF ONTARIO AND LAKE SUPERIOR THIS EVENING. TAIL END OF VORT WILL
BRUSH NORTH-CENTRAL TO NORTHEAST WISCONSIN WITH A FEW HOURS OF
MODERATE MID-LEVEL FORCING. THOUGH THE SHORT RANGE MODELS SUGGEST
PRECIP WOULD BE POSSIBLE AS FAR SOUTH AS THE U.P. BORDER...AREA OF
FORCING AND PRECIP UPSTREAM SUGGEST PRECIP COULD REACH A LITTLE
FARTHER SOUTH INTO WISCONSIN...SO WILL KEEP A SMALL POP OVER THE NE
1/3RD OF THE AREA...WHICH BACKS OFF CHANCES A WEE BIT FROM THE
PREVIOUS FORECAST. NOT EXPECTING MUST ACCUMS HOWEVER. BEHIND THE
SHORTWAVE...WINDS TURN TO THE NORTHWEST AND WILL ADVECT IN ARCTIC
AIR INTO THE REGION. THIS WOULD BE GOOD FOR LAKE EFFECT CHANCES
EXCEPT THAT VERY DRY AIR WILL ALSO ARRIVE AS WELL. SO WILL KEEP
COVERAGE SCT WITH LITTLE ACCUMS. AS HIGH PRESSURE BUILDS IN
LATE...WINDS WILL FALL OFF AND SKIES WILL CLEAR. THIS WILL PROMOTE
TUMBLING TEMPS. LIKE WHAT THE PREVIOUS SHIFT PUT IN FOR MIN TEMPS
AND HAVE ONLY MADE A FEW MINOR CHANGES.
SUNDAY...SURFACE PRESSURE CENTERED ACROSS THE REGION INITIALLY WILL
MOVE TO THE EASTERN GREAT LAKES BY LATE IN THE AFTERNOON. AS WINDS
TURN TO THE EAST AROUND THE HIGH...SHOULD SEE MID LAKE EFFECT BAND
OR BANDS PUSH ONSHORE DURING THE LATE MORNING HOURS. SOME OF THE
REMNANT CLOUDS MAY SPREAD ACROSS INTO CENTRAL WISCONSIN DURING THE
AFTERNOON. SO IN THE END...WILL SEE A MOSTLY SUNNY TO PARTLY CLOUDY
DAY WITH HIGHS A COUPLE DEGREES COOLER THAN TODAY.
.LONG TERM...MAIN FORECAST CONCERNS WILL BE SNOW AMOUNTS LATE
SUNDAY NIGHT INTO MONDAY NIGHT...LAKE EFFECT POTENTIAL...AND
TEMPS. STILL NO SIGNS OF A SPRING-TIME WARM UP AS PERSISTENT
BLOCKING PATTERN REMAINS SITUATED ACROSS EASTERN CANADA AND THE
WESTERN ATLANTIC.
SUNDAY NIGHT WILL START OFF QUIET AS HIGH PRESSURE PUSHES INTO THE
EASTERN GREAT LAKES. THE DEPARTING HIGH WILL ALLOW A SURFACE LOW
PRESSURE TO ORGANIZE AND MOVE INTO THE WESTERN GREAT LAKES...AS A
POTENT SHORTWAVE AND UPPER TROF ALSO PUSH TOWARD THE AREA. FARTHER
SOUTH...A WEAKER SURFACE LOW AND SHORTWAVE WILL BE PUSHING ACROSS
THE OHIO VALLEY. MODELS ARE NOT IN COMPLETE AGREEMENT ON HOW
THESE TWO WILL PHASE OR NOT PHASE...BUT MODELS HAVE BEEN FAIRLY
CONSISTENT FOR THE PAST COUPLE OF RUNS HOLDING OFF ANY POSSIBLE
PHASING UNTIL IT IS EAST OF WISCONSIN. THE SOUTHERN STREAM
SYSTEM STILL LOOKS TO STAY TOO FAR SOUTH TO BRING ANY PRECIP TO
THE AREA SUNDAY AFTERNOON AND EVENING...SO WILL NEED TO WAIT FOR
THE NORTHERN STREAM SYSTEM FOR ANY ACCUMULATING SNOW. CLOUDS WILL
BE INCREASING THROUGH THE NIGHT AS THE NORTHERN SYSTEM APPROACHES.
TEMPS COULD FALL QUICKLY DURING THE EVENING AS SKIES WILL START
OFF PARTLY CLOUDY OR MOSTLY CLEAR...SO LOOK FOR EVENING LOWS WITH
TEMPS SLOWLY RISING OVERNIGHT AS CLOUDS THICKEN AND SNOW
APPROACHES.
SNOW WILL OVERSPREAD THE AREA FROM WEST TO EAST VERY LATE SUNDAY
NIGHT AND MONDAY MORNING AS THE LOW PRESSURE SYSTEM AND POTENT
SHORTWAVE PUSH INTO THE WESTERN GREAT LAKES. MODELS IN DECENT
AGREEMENT WITH THE TRACK...TAKING THE SURFACE LOW TOWARD WESTERN
LAKE SUPERIOR. GEM SEEMS TO REMAIN AN OUTLIER WITH A MUCH SLOWER
SOLUTION. SOME UNCERTAINTY REMAINS ON HOW MUCH (IF ANY) MOISTURE
FROM THE SOUTHERN STREAM WILL GET PULLED INTO THE NORTHERN
SYSTEM...WHICH WILL FACTOR IN TO THE SNOW TOTALS. THIS LOOKS TO BE
A FAIRLY QUICK HITTING SYSTEM WITH THE BEST SNOWS OCCURRING IN A
12 HOUR WINDOW AS BEST Q-G FORCING...LIFT FROM THE LEFT FRONT QUAD
OF AN UPPER JET...AND SURFACE FRONT CROSS THE AREA. STILL LOOKING
FOR A WIDESPREAD 2-5 INCH SNOW THROUGH 06Z TUESDAY...WITH A FEW
HIGHER TOTALS POSSIBLE...ESPECIALLY OVER CENTRAL AND NORTHERN WI.
WILL CONTINUE TO HOLD OFF ON ANY HEADLINE AS QUESTIONS REMAIN ON
HOW MUCH MOISTURE THERE WILL BE...PLUS THE MAJORITY OF THE SNOW
WILL FALL DURING THE DAY WITH TEMPS IN THE UPPER 20S AND LOWER 30S
AND THE MID MARCH SUN WILL HELP WARM THE GROUND...SO DAYTIME
ACCUMULATIONS ON THE ROADS MAY BE LIMITED...ESPECIALLY OVER THE
EAST.
SNOW WILL DIMINISH QUICKLY AS THE BEST DYNAMICS PUSH NORTH/EAST OF
THE AREA MONDAY NIGHT. CYCLONIC FLOW COULD KEEP SOME LIGHT SNOW OR
FLURRIES ACROSS NORTHERN WI OVERNIGHT...BUT WINDS LOOK TOO
WESTERLY TO GET ANY SUBSTANTIAL LAKE EFFECT ACTIVITY INTO NORTH-
CENTRAL WI. AN ADDITIONAL INCH IS POSSIBLE ACROSS THE NORTH. WEST
WINDS WILL KICK UP BEHIND THE SURFACE FRONT...WHICH WILL PRODUCE
SOME BLOWING AND DRIFTING SNOW. STRONG COLD AIR ADVECTION WILL
BEGIN MONDAY NIGHT AND CONTINUE INTO TUESDAY. MODELS HINT AT
ANOTHER SHORTWAVE ROTATING THROUGH THE AREA ON TUESDAY...WITH
CYCLONIC FLOW IN PLACE ALONG WITH LINGERING MOISTURE. WILL ADD
SOME FLURRY MENTION COVER FOR NOW. GUSTY NE WINDS WILL COMBINE
WITH TEMPS ONLY IN THE 20S TO PRODUCE A BLUSTERY/COOL DAY. WINDS
BEGIN TO TURN MORE TO THE NW TUESDAY AFTERNOON...THEN REMAIN NW
INTO THURSDAY MORNING. DELTA T VALUES WILL HOVER IN THE MID TEENS
TO PRODUCE A LONG DURATION LAKE EFFECT SNOW EVENT. HIGHEST
ACCUMULATIONS WILL REMAIN IN UPPER MICHIGAN...BUT DO EXPECT AT
LEAST SOME ACCUMULATION IN THE FAVORED LAKE EFFECT AREAS OF NORTH-
CENTRAL WI.
CYCLONIC FLOW AROUND THE LOW WHICH BY LATE IN THE WEEK WILL ONLY
MOVE INTO THE EASTERN GREAT LAKES WILL KEEP COOL CONDITIONS ACROSS
THE REGION UNDER PARTLY CLOUDY SKIES. MODELS HAVE THE SYSTEM AT
THE END OF THE WEEK WELL SOUTH OF THE REGION...SO WILL CONTINUE
WITH A DRY FORECAST.
&&
.AVIATION...SCT MVFR CIGS ACROSS THE FAR NORTH NEXT FEW
HOURS...OTHERWISE SKIES CLEARING OVERNIGHT AS HIGH PRESSURE
BUILDS INTO THE REGION. VFR CONDITIONS ON SUNDAY. LOWER CIGS AND
VSBYS DVLPG FROM W TO E AFTER 09Z MONDAY AHEAD OF NEXT SYSTEM.
JKL
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
622 PM CDT SAT MAR 16 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND SUNDAY.
THE LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW THIS
MORNINGS LIGHT SNOW DIMINISHING AS IT MOVES SOUTH OVER SOUTHERN
WISCONSIN. AFTER A BRIEF MOMENT OF CLEARING...WEST WINDS HAVE
BROUGHT IN ADDITIONAL CLOUD COVER ACROSS MUCH OF NORTHERN WISCONSIN
AND THE UPPER PENINSULA. LOOKING UPSTREAM...A STRONG SHORTWAVE IS
DIVING TO THE SOUTH ALONG THE MANITOBA/ONTARIO BORDER. SNOW SHOWERS
FROM THIS WAVE ARE MAKING IT TO THE NORTHERN MANITOBA BORDER EARLY
THIS AFTERNOON. SNOW SHOWER POTENTIAL FROM THIS WAVE AND
TEMPERATURES ARE THE MAIN FORECAST CONCERNS.
TONIGHT...A STRONG SHORTWAVE WILL SWING SE ACROSS THE SOUTHERN HALF
OF ONTARIO AND LAKE SUPERIOR THIS EVENING. TAIL END OF VORT WILL
BRUSH NORTH-CENTRAL TO NORTHEAST WISCONSIN WITH A FEW HOURS OF
MODERATE MID-LEVEL FORCING. THOUGH THE SHORT RANGE MODELS SUGGEST
PRECIP WOULD BE POSSIBLE AS FAR SOUTH AS THE U.P. BORDER...AREA OF
FORCING AND PRECIP UPSTREAM SUGGEST PRECIP COULD REACH A LITTLE
FARTHER SOUTH INTO WISCONSIN...SO WILL KEEP A SMALL POP OVER THE NE
1/3RD OF THE AREA...WHICH BACKS OFF CHANCES A WEE BIT FROM THE
PREVIOUS FORECAST. NOT EXPECTING MUST ACCUMS HOWEVER. BEHIND THE
SHORTWAVE...WINDS TURN TO THE NORTHWEST AND WILL ADVECT IN ARCTIC
AIR INTO THE REGION. THIS WOULD BE GOOD FOR LAKE EFFECT CHANCES
EXCEPT THAT VERY DRY AIR WILL ALSO ARRIVE AS WELL. SO WILL KEEP
COVERAGE SCT WITH LITTLE ACCUMS. AS HIGH PRESSURE BUILDS IN
LATE...WINDS WILL FALL OFF AND SKIES WILL CLEAR. THIS WILL PROMOTE
TUMBLING TEMPS. LIKE WHAT THE PREVIOUS SHIFT PUT IN FOR MIN TEMPS
AND HAVE ONLY MADE A FEW MINOR CHANGES.
SUNDAY...SURFACE PRESSURE CENTERED ACROSS THE REGION INITIALLY WILL
MOVE TO THE EASTERN GREAT LAKES BY LATE IN THE AFTERNOON. AS WINDS
TURN TO THE EAST AROUND THE HIGH...SHOULD SEE MID LAKE EFFECT BAND
OR BANDS PUSH ONSHORE DURING THE LATE MORNING HOURS. SOME OF THE
REMNANT CLOUDS MAY SPREAD ACROSS INTO CENTRAL WISCONSIN DURING THE
AFTERNOON. SO IN THE END...WILL SEE A MOSTLY SUNNY TO PARTLY CLOUDY
DAY WITH HIGHS A COUPLE DEGREES COOLER THAN TODAY.
.LONG TERM...MAIN FORECAST CONCERNS WILL BE SNOW AMOUNTS LATE
SUNDAY NIGHT INTO MONDAY NIGHT...LAKE EFFECT POTENTIAL...AND
TEMPS. STILL NO SIGNS OF A SPRING-TIME WARM UP AS PERSISTENT
BLOCKING PATTERN REMAINS SITUATED ACROSS EASTERN CANADA AND THE
WESTERN ATLANTIC.
SUNDAY NIGHT WILL START OFF QUIET AS HIGH PRESSURE PUSHES INTO THE
EASTERN GREAT LAKES. THE DEPARTING HIGH WILL ALLOW A SURFACE LOW
PRESSURE TO ORGANIZE AND MOVE INTO THE WESTERN GREAT LAKES...AS A
POTENT SHORTWAVE AND UPPER TROF ALSO PUSH TOWARD THE AREA. FARTHER
SOUTH...A WEAKER SURFACE LOW AND SHORTWAVE WILL BE PUSHING ACROSS
THE OHIO VALLEY. MODELS ARE NOT IN COMPLETE AGREEMENT ON HOW
THESE TWO WILL PHASE OR NOT PHASE...BUT MODELS HAVE BEEN FAIRLY
CONSISTENT FOR THE PAST COUPLE OF RUNS HOLDING OFF ANY POSSIBLE
PHASING UNTIL IT IS EAST OF WISCONSIN. THE SOUTHERN STREAM
SYSTEM STILL LOOKS TO STAY TOO FAR SOUTH TO BRING ANY PRECIP TO
THE AREA SUNDAY AFTERNOON AND EVENING...SO WILL NEED TO WAIT FOR
THE NORTHERN STREAM SYSTEM FOR ANY ACCUMULATING SNOW. CLOUDS WILL
BE INCREASING THROUGH THE NIGHT AS THE NORTHERN SYSTEM APPROACHES.
TEMPS COULD FALL QUICKLY DURING THE EVENING AS SKIES WILL START
OFF PARTLY CLOUDY OR MOSTLY CLEAR...SO LOOK FOR EVENING LOWS WITH
TEMPS SLOWLY RISING OVERNIGHT AS CLOUDS THICKEN AND SNOW
APPROACHES.
SNOW WILL OVERSPREAD THE AREA FROM WEST TO EAST VERY LATE SUNDAY
NIGHT AND MONDAY MORNING AS THE LOW PRESSURE SYSTEM AND POTENT
SHORTWAVE PUSH INTO THE WESTERN GREAT LAKES. MODELS IN DECENT
AGREEMENT WITH THE TRACK...TAKING THE SURFACE LOW TOWARD WESTERN
LAKE SUPERIOR. GEM SEEMS TO REMAIN AN OUTLIER WITH A MUCH SLOWER
SOLUTION. SOME UNCERTAINTY REMAINS ON HOW MUCH (IF ANY) MOISTURE
FROM THE SOUTHERN STREAM WILL GET PULLED INTO THE NORTHERN
SYSTEM...WHICH WILL FACTOR IN TO THE SNOW TOTALS. THIS LOOKS TO BE
A FAIRLY QUICK HITTING SYSTEM WITH THE BEST SNOWS OCCURRING IN A
12 HOUR WINDOW AS BEST Q-G FORCING...LIFT FROM THE LEFT FRONT QUAD
OF AN UPPER JET...AND SURFACE FRONT CROSS THE AREA. STILL LOOKING
FOR A WIDESPREAD 2-5 INCH SNOW THROUGH 06Z TUESDAY...WITH A FEW
HIGHER TOTALS POSSIBLE...ESPECIALLY OVER CENTRAL AND NORTHERN WI.
WILL CONTINUE TO HOLD OFF ON ANY HEADLINE AS QUESTIONS REMAIN ON
HOW MUCH MOISTURE THERE WILL BE...PLUS THE MAJORITY OF THE SNOW
WILL FALL DURING THE DAY WITH TEMPS IN THE UPPER 20S AND LOWER 30S
AND THE MID MARCH SUN WILL HELP WARM THE GROUND...SO DAYTIME
ACCUMULATIONS ON THE ROADS MAY BE LIMITED...ESPECIALLY OVER THE
EAST.
SNOW WILL DIMINISH QUICKLY AS THE BEST DYNAMICS PUSH NORTH/EAST OF
THE AREA MONDAY NIGHT. CYCLONIC FLOW COULD KEEP SOME LIGHT SNOW OR
FLURRIES ACROSS NORTHERN WI OVERNIGHT...BUT WINDS LOOK TOO
WESTERLY TO GET ANY SUBSTANTIAL LAKE EFFECT ACTIVITY INTO NORTH-
CENTRAL WI. AN ADDITIONAL INCH IS POSSIBLE ACROSS THE NORTH. WEST
WINDS WILL KICK UP BEHIND THE SURFACE FRONT...WHICH WILL PRODUCE
SOME BLOWING AND DRIFTING SNOW. STRONG COLD AIR ADVECTION WILL
BEGIN MONDAY NIGHT AND CONTINUE INTO TUESDAY. MODELS HINT AT
ANOTHER SHORTWAVE ROTATING THROUGH THE AREA ON TUESDAY...WITH
CYCLONIC FLOW IN PLACE ALONG WITH LINGERING MOISTURE. WILL ADD
SOME FLURRY MENTION COVER FOR NOW. GUSTY NE WINDS WILL COMBINE
WITH TEMPS ONLY IN THE 20S TO PRODUCE A BLUSTERY/COOL DAY. WINDS
BEGIN TO TURN MORE TO THE NW TUESDAY AFTERNOON...THEN REMAIN NW
INTO THURSDAY MORNING. DELTA T VALUES WILL HOVER IN THE MID TEENS
TO PRODUCE A LONG DURATION LAKE EFFECT SNOW EVENT. HIGHEST
ACCUMULATIONS WILL REMAIN IN UPPER MICHIGAN...BUT DO EXPECT AT
LEAST SOME ACCUMULATION IN THE FAVORED LAKE EFFECT AREAS OF NORTH-
CENTRAL WI.
CYCLONIC FLOW AROUND THE LOW WHICH BY LATE IN THE WEEK WILL ONLY
MOVE INTO THE EASTERN GREAT LAKES WILL KEEP COOL CONDITIONS ACROSS
THE REGION UNDER PARTLY CLOUDY SKIES. MODELS HAVE THE SYSTEM AT
THE END OF THE WEEK WELL SOUTH OF THE REGION...SO WILL CONTINUE
WITH A DRY FORECAST.
&&
.AVIATION...UPPER LEVEL DISTURBANCE WILL MOVE ACROSS LAKE
SUPERIOR THIS EVENING. POTENTIAL IS THERE FOR SNOW SHOWERS TO
MOVE ACROSS NORTHERN WISCONSIN AHEAD OF THIS FEATURE. PROBABILITY
IS TOO LOW TO INCLUDE IN THE RHI TAF AT THIS TIME...BUT POTENTIAL
FOR A BRIEF PERIOD OF MVFR VSBYS IN LIGHT SNOW IS THERE
THIS EVENING...ESP NORTH OF RHI. SKIES TO CLEAR AFTER MIDNIGHT WHEN
HIGH PRESSURE BUILDS INTO THE REGION. VFR CONDITIONS ON SUNDAY.
JKL
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
313 PM CDT FRI MAR 15 2013
.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
313 PM CDT FRI MAR 15 2013
MAIN FORECAST CONCERNS THIS PACKAGE...PRECIP TYPES/AMOUNTS
TONIGHT...NEXT SYSTEM TO IMPACT THE AREA LATE SUN NIGHT INTO MON
NIGHT...TEMPERATURES.
18Z DATA ANALYSIS HAD A BROAD BUT WEAK AREA OF LOW PRESSURE OVER NEB
WITH A TROUGH/FRONT NORTHEAST TO A LOW IN SOUTHWEST QUEBEC. AREA
RADARS DEPICTED A SHORTWAVE MOVING EAST-SOUTHEAST ACROSS THE AREA AT
MID-DAY...MORESO THAN WV IMAGERY. NEXT UPSTREAM SHORTWAVE OVER
SOUTHERN SASKAT/NORTHWEST ND MUCH MORE EVIDENT IN WV IMAGERY. MIX OF
PRECIP WITH THE FIRST WAVE EXITING EAST OF THE MS RIVER AT 18Z...
WHILE PRECIP /MAINLY SNOW/ WITH THE UPSTREAM WAVE WAS SPREADING
EAST-SOUTHEAST ACROSS ND INTO MN. WITH THE CLOUDS AND MIXED PRECIP
OR SNOW...MID-DAY TEMPS ONCE AGAIN BELOW MID MARCH NORMALS.
15.12Z MODELS INITIALIZED WELL AND OFFER QUITE SIMILAR SOLUTIONS FOR
TONIGHT INTO MON NIGHT. SOME MINOR DIFFERENCES REMAIN WITH SOUTHWARD
EXTENT OF PRECIP TONIGHT AND TIMING/AMOUNTS OF SNOW WITH THE SYSTEM
CENTERED ON MONDAY. THIS NOT UNEXPECTED WITH THE MONDAY SYSTEM
SHORTWAVE TROUGH STILL SOUTH OF THE GULF OF AK. DPROG/DT OF 500MB
HGTS AT 15.12Z SHOWED THE MODEL RUNS OF 13.12Z AND 14.12Z VERIFIED
VERY WELL ACROSS NOAM/EASTERN PAC. TIGHTER CONSENSUS AS ONE
SHORTWAVE PASSES TONIGHT AND THE NEXT STRONGER ONE MOVES ON THE PAC
NORTHWEST COAST SUN. TREND FAVORS FASTER OF EARLIER RUNS WITH THE
PAC NORTHWEST TROUGH LATE SAT. CONSISTENCY REMAINS GOOD AS THIS WAVE
CROSSES THE ROCKIES SAT NIGHT/SUN. BETTER CONSENSUS AS IT CROSSES
THE PLAINS SUN NIGHT BUT DIFFERENCES REMAIN AS IT MOVES INTO THE
UPPER MIDWEST MON. BY LATE MON TREND OF MORE CONSISTENT MODELS
FAVORS SLOWER OF EARLIER RUNS WITH THE TROUGH INTO THE UPPER
MIDWEST. OVERALL BETTER RUN-TO-RUN CONSISTENCY TO GFS/ECMWF THRU
THE PERIOD. NAM DOES APPEAR AS A BIT OF AN OUTLIER IN THE SUN
NIGHT/MON PERIOD...AS DOES THE GEM. CHECK OF OBS VS. MODEL DATA AT
18Z SHOWED ALL TO BE REASONABLE WITH THE CENTRAL CONUS MASS FIELDS.
PER WV IMAGERY...STRONGER/SLOWER OF MODELS LOOKED BETTER WITH THE
MT/ND/SASKAT SHORTWAVE. A BLEND OF THE MODELS LOOKED BEST WITH THE
12-18Z PRECIP ACROSS THE REGION. WITH TREND TOWARD THE TIGHTER
CONSENSUS AND BETTER RUN-TO-RUN CONSISTENCY BY GFS/ECMWF...FAVORED
THE MODEL/ENSEMBLE CONSENSUS WEIGHTED TOWARD THE MORE CONSISTENT
GFS/ECMWF. SHORT-TERM FCST CONFIDENCE AVERAGE TO GOOD THIS CYCLE.
FOR THE SHORT TERM...NEXT ROUND OF DEEPER FORCING/LIFT WITH THE
MT/ND/SASKAT SHORTWAVE SPREADS QUICKLY SOUTHEAST ACROSS THE AREA
THIS EVENING INTO THE OVERNIGHT HOURS. TIGHTER MODEL CONSENSUS
SPREADS PRECIP ACROSS ROUGHLY THE SAME AREA AS PRECIP MOVED ACROSS
THIS MORNING. CONTINUED 80-100 PERCENT PRECIP CHANCES OVER THE
NORTHEAST 3/4 OF THE FCST AREA /MAINLY THIS EVENING/ TRENDING TO 30-
60 PERCENT OVER THE SOUTHWEST QUARTER WHERE LIFT/COLUMN SATURATION
WILL BE WEAKER.
LATEST MODEL SUITE INDICATES MOISTURE WILL BE DEEP ENOUGH WITH ICE
IN THE TOP OF THE CLOUDS AS THE WAVE/LIFT PASS THIS EVENING.
HOWEVER...THE WARM LAYER ALOFT WITH TEMPS AROUND 850MB IN THE 0C TO
+4C RANGE REMAINS OVER THE ABOUT THE SOUTHWEST 1/2 OF THE FCST AREA
AT 00Z...SLOWLY COOLING TO BELOW 0C BY 06Z TONIGHT. BOUNDARY LAYER
TEMPS REMAIN ABOVE 32F THRU THE EARLY EVENING AS WELL...SO PRECIP
TYPE ISSUES CONTINUE THIS EVENING. WITH DEEPER MOISTURE/ICE IN THE
CLOUDS...HAVE TRENDED TOWARD MORE -SN/PL/-RA DURING THE EVENING VS.
-FZDZ/-FZRA AS THE WAVE/LIFT PASS. MOISTURE DOES SHALLOW WITH LOSS
OF ICE ONCE THE WAVE PASSES...SO DID CONTINUE SOME -FZDZ MENTION
WEST OF THE MS RIVER LATE THIS EVENING...SPREADING EAST ACROSS THE
AREA DURING THE OVERNIGHT HOURS. WITH SUNSET AND LOSS OF IR
RADIATION KEEPING ROAD SURFACE WARMER...COLD GROUND AND MIXED PRECIP
TYPES/-SN THIS EVENING...WILL CONTINUE WINTER WEATHER ADVISORY.
FOR SAT...MODEL SOUNDINGS CONTINUE TO SHOW STEEP LOW LEVEL LAPSE
RATES...LOW LEVEL MOISTURE AND WEAK INSTABILITY OVER THE AREA.
FLURRIES MENTION ON SAT STILL LOOKS WELL TRENDED. CONSIDERED ADDING
-SHSN WITH A 15-20 PERCENT PRECIP CHANCE FOR SAT BUT MOISTURE NOT
OVERLY DEEP AND LOWER LEVEL CAPPED BY A STRONG INVERSION NEAR 850MB.
THIS STRONG INVERSION REMAINS OVER THE AREA SAT THRU SUN WITH PLENTY
OF LOW LEVEL MOISTURE LOOKING TO REMAIN TRAPPED UNDER IT. EVEN AS
CAN HIGH PRESSURE WITH ANTI-CYCLONIC FLOW BUILDS IN DURING THIS
PERIOD...NOT CONVINCED CLOUDS WILL CLEAR. BEST SHOT WILL BE LATER
SAT NIGHT/SUN MORNING...WITH HIGH CLOUDS AHEAD OF THE NEXT TROUGH
ALREADY SPREADING EAST ACROSS MN/IA/WI LATER SUN. LEFT SKIES PARTLY-
MOSTLY CLOUDY SAT NIGHT/SUN.
FAVORING A MODEL CONSENSUS WEIGHTED TOWARD THE MORE CONSISTENT
GFS/ECMWF...THE NEXT TROUGH SPREADS INCREASING MOISTURE/FORCING LIFT
WEST TO EAST ACROSS THE FCST AREA LATER SUN NIGHT/MON. MODEL
SOUNDINGS INDICATE COLUMN COLD ENOUGH FOR ALL SNOW WITH THIS WAVE...
OVER ALL BUT THE FAR SOUTHEAST END OF THE FCST AREA WHERE BOUNDARY
LAYER TEMPS MAY WARM ENOUGH FOR A -RA/-SN MIX MON AFTERNOON OR
SHALLOWER MOISTURE/LACK OF ICE IN THE CLOUDS MAY ALLOW FOR SOME
-DZ/-FZDZ. JUST LEFT A -RA/-SN MIX ACROSS THE SOUTHEAST END OF THE
FCST AREA MON AFTERNOON FOR NOW. GFS/ECMWF/SREF CONSENSUS AT THIS
TIME PRODUCES 1.5 TO 5 INCHES OF SNOW ACROSS THE AREA LATE SUN
NIGHT/MON...BUT TOO EARLY TO BE ISSUING ANY POTENTIAL WINTER WEATHER
ADVISORIES FOR THIS SNOW. LATEST MODEL SUITE SWEEPS BULK OF THE
LIFT/PRECIP OUT OF THE AREA BY MON EVENING WITH ONLY LINGERING/
DIMINISHING -SN CHANCES MON NIGHT.
FAVORED A BLEND OF THE NUMERICAL GUIDANCE LOWS/HIGHS FOR TONIGHT
THRU MON NIGHT. WILL HAVE TO WATCH LOWS FOR SUN MORNING...WITH MORE
CLEARING...FCST GRID LOWS FOR SAT NIGHT MAY END UP A CATEGORY OR
TWO TOO WARM. WITH MORE -SN THRU THE DAY...HIGHS MON MAY END UP A
CATEGORY TOO WARM AS WELL.
.LONG TERM...TUESDAY THROUGH FRIDAY
313 PM CDT FRI MAR 15 2013
15.00Z MODELS SHOWING IMPROVED CONSISTENCY ON TUE AS THE MONDAY
TROUGH MOVES INTO EASTERN NOAM AND HGTS RISE OVER THE UPPER MIDWEST.
THE IMPROVED CONSISTENCY IS SHORT-LIVED AS MODELS BEGIN TO DIFFER
WILDLY ON THE AMPLITUDE OF RIDGING TRYING TO BUILD INTO CENTRAL
NOAM...THE NEXT STRONGER TROUGH ONTO THE WEST COAST AND SMALLER
SCALE SHORTWAVES THRU THE FLOW OVER WESTERN/CENTRAL NOAM. THESE
DIFFERENCES CONTINUE THU/FRI AS TROUGHING MOVES THRU THE ROCKIES THU
AND INTO THE CENTRAL CONUS FRI. BOTH BETWEEN MODEL AND RUN-TO-RUN
CONSISTENCY OF 15.00Z MODELS LEAVE QUITE A BIT TO BE DESIRED BY
THU/FRI. CONSIDERABLE SPREAD SEEN AMONG THE ENSEMBLE MEMBERS BY
THU/FRI AS WELL...HOWEVER...15.12Z GFS/ECMWF/GEM MUCH MORE SIMILAR
IN THE DAY 4-7 PERIOD WITH GFS TRENDING STRONGLY TOWARD THE ECMWF IN
THE WED-FRI PERIOD. FCST CONFIDENCE AVERAGE TUE-FRI. WITH TROUGH
EXITING EAST TUE AND HGTS RISING...CAN HIGH PRESSURE BUILDS SOUTH
AND EAST INTO THE REGION...FOR A DRY DAY WITH CONTINUED BELOW NORMAL
TEMPS. THE HIGH DRIFTS EAST ACROSS THE REGION WED...THEN 15.12Z
MODEL CONSENSUS HOLDS THIS HIGH OVER THE REGION WITH NORTH/NORTHWEST
FLOW ALOFT INTO THE END OF THE WEEK. WITH THIS GFS SHIFT...MID TO
LATE NEXT WEEK HAS TRENDED DRY LIKE ECMWF HAS BEEN...THUS NO MENTION
OF PRECIP IN THE DAY 4-7 PERIOD AT THIS TIME. HIGH CONFIDENCE THAT
TEMPS WILL REMAIN BELOW NORMAL IN THE DAY 4-7 PERIOD AND THIS TREND
LOOKS WELL CAPTURED BY THE MODEL/ENSEMBLE CONSENSUS.
&&
.AVIATION...THROUGH 18Z SATURDAY
1219 PM CDT FRI MAR 15 2013
THE FIRST SHORT WAVE TROUGH IS MOVING PAST THE REGION AND TAKING
ITS PRECIPITATION SHIELD WITH IT. WILL NOT INCLUDE ANY
PRECIPITATION FROM THIS WAVE AT KRST AND ONLY FOR AN HOUR AT KLSE.
ONCE THE PRECIPITATION ENDS...CONDITIONS REMAIN IFR AS ENOUGH FOG
IS KEEPING THE VISIBILITY BELOW 3 MILES WITH CEILINGS AT OR BELOW
1K FEET. THE NEXT SHORT WAVE TROUGH IS MOVING INTO NORTH DAKOTA
WITH THE NEXT ROUND OF PRECIPITATION. EXPECT THIS SYSTEM WILL
QUICKLY DROP SOUTHEAST AND START SPREADING PRECIPITATION BACK IN
EARLY THIS EVENING. INITIALLY EXPECTING THIS TO START OUT AS A
RAIN/SNOW MIX BEFORE GOING TO ALL SNOW. THE 15.15Z RAP CONTINUES
TO SUGGEST THE POTENTIAL FOR A LOSS OF ICE IN THE CLOUDS AS THE
PRECIPITATION ENDS. WILL INCLUDE A PERIOD OF A FREEZING
DRIZZLE/SNOW MIX AT THE TAIL END...BUT THERE IS ALSO THE
POSSIBILITY THAT THE PRECIPITATION COULD HAVE ENDED BY THE TIME
THE LOSS OF ICE OCCURS. ONCE THE PRECIPITATION ENDS...SHOULD SEE
THE VISIBILITY IMPROVE TO MVFR WHILE THE CEILINGS WILL EITHER BE
MVFR OR IFR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
313 PM CDT FRI MAR 15 2013
WI...WINTER WEATHER ADVISORY UNTIL 1 AM CDT SATURDAY FOR WIZ017-029-
032>034-041>044-053-055.
MN...WINTER WEATHER ADVISORY UNTIL 1 AM CDT SATURDAY FOR MNZ079-
086>088-096.
IA...NONE.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION.....04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1219 PM CDT FRI MAR 15 2013
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
300 AM CDT FRI MAR 15 2013
FORECAST FOCUS IS ON THE CONTINUATION OF WINTER WEATHER TODAY AND
TONIGHT.
TWO PRONGED PCPN EVENT FOR THE REGION TODAY. THE FIRST WILL COME
THANKS MOSTLY TO LOW LEVEL THERMODYNAMICS...EVIDENCED ON THE 285-300
K ISENTROPIC SFCS AND 850 MB WARM AIR ADVECTION. THIS MOVES
NORTHWEST-SOUTHEAST ACROSS THE FORECAST AREA BETWEEN 12-21Z TODAY.
THE SECOND PART WILL COME AFTER 00Z WHEN AN UPPER LEVEL SHORTWAVE
SLIDES ALONG THE NORTHWEST FLOW...MOVING ACROSS NORTHERN PORTIONS OF
MN/WI...EXITING SOUTHEAST AFTER 06Z. THERE ARE PERIODS OF LOW LEVEL
FRONTOGENETIC LIFT TO AID BOTH OF THESE TIME FRAMES.
BOTH MAIN FORCING MECHANISMS WILL PRODUCE SOME PCPN. QUESTIONS
ABOUND AS TO WHAT TYPE AND HOW MUCH...WITH TEMPERATURE PROFILES AND
ICE IN CLOUD ISSUES MUDDLING THE ISSUE.
LOOKING FIRST AT THE SATURATION...TIME/HEIGHT X-SECTIONS AND BUFKIT
SOUNDINGS SHOW A DEEPENING CLOUD LAYER AS THE THERMODYNAMIC FORCING
MOVES IN...WITH ICE IN THE CLOUD. SATURATION ALSO DEEP ENOUGH FOR
ICE WITH THE SHORTWAVE FOR THIS EVENING. IN BETWEEN THOUGH THERE IS
SOME SHALLOWING OUT OF THE CLOUD LAYER SUCH THAT ICE COULD BE
LOST...THUS MAKING LIQUID A MORE LIKELY PCPN OUTCOME. ON THE
BACKSIDE OF THE SHORTWAVE...COULD LOSE ICE AGAIN...BRINGING LIQUID
PCPN BACK INTO THE PICTURE.
LOOKING AT THE VERTICAL TEMPERATURE PROFILE...NORTH-SOUTH RUNNING
TIME/HEIGHT X-SECTIONS VIA THE GFS AND NAM SHOW A WARM INTRUSION
CENTERED AROUND 850 MB NEAR EAU AT 12Z THIS MORNING...RETREATING
SOUTH OF LSE BY MID AFTERNOON. GFS IS A BIT COLDER...BUT ALSO HAS A
BIT MORE SOUTH TRACK FOR THE PCPN. SOUNDINGS AND X-SECTIONS SUGGEST
THERE WOULD BE PARTIAL MELTING FOR SOUTHERN PORTIONS OR THE MORNING
PCPN BAND...WHICH POINTS TO SLEET AS A PCPN TYPE. HOWEVER...PARTS OF
NORTHEAST IA/SOUTHWEST WI COULD BE WARM/DEEP ENOUGH FOR FULL
MELTING...BEFORE COOLING TO THE WET BULB TEMP...THAT LIQUID WOULD BE
FAVORED. THAT WOULD BE FOR THE FAR SOUTHERN PORTION OF THE MORNING
PCPN...AND MOSTLY IN THE GFS SOLUTION. HOWEVER...ANY ENHANCED RADAR
RETURNS/PCPN RATES WOULD FAVOR MORE COOLING...AND A SLEET/SNOW
MIX.
FOR SFC TEMPS...EXPECT A BUMP ABOVE FREEZING ACROSS NORTHEAST
IA/SOUTHWEST WI THIS MORNING. SO...IF THE PCPN DOES FALL AS A
LIQUID...THE THREAT FOR FREEZING RAIN LOOKS TO BE FOR SHORT PERIOD
DURING THE EARLY MORNING.
MESSY PCPN TYPE FORECAST. FEEL CURRENT SCENARIO FAVORS A FREEZING
RAIN CHANGING TO RAIN LATE MORNING FOR NORTHEAST IA/SOUTHWEST WI.
ACROSS THE MIDDLE PART OF THE FORECAST AREA...A MIX OF JUST ABOUT
EVERYTHING WILL BE POSSIBLE THIS MORNING. FOR THE NORTH...SNOW IS
MOST LIKELY. FOR THE AFTERNOON...MOSTLY SNOW RAIN/SNOW FOR THE
NORTHERN 1/2...WITH RAIN IN THE SOUTH. TONIGHT...LOOKING FOR SNOW
WITH SOME FREEZING DRIZZLE CHANCES.
EXPECT 2 TO 4 INCHES OF SNOW ALONG AND NORTH OF I-94...DROPPING
OFF SOUTH OF THERE. SOME ICING ON EXPOSED...COLD SFCS WILL BE
POSSIBLE EARLY THIS MORNING AND LATER TONIGHT...MOSTLY SOUTH OF
I-90.
WILL CONTINUE THE WINTER WEATHER ADVISORY.
.LONG TERM...MONDAY THROUGH THURSDAY
330 PM CDT THU MAR 14 2013
MAIN FORECAST CONCERNS IN THE LONG TERM CONTINUE TO FOCUS ON A STORM
THAT IS SLATED TO MOVE ACROSS THE REGION ON MONDAY. THE GFS/ECMWF
HAVE GRADUALLY SHIFTED TO THE NORTHWEST OVER THE PAST FEW DAYS WITH
THE TRACK OF THE UPPER LEVEL TROUGH/SFC LOW...SHIFTING THE HEART OF
THE STORM/S HEAVY SNOW/DEFORMATION BAND OVER NORTHERN MN.
HOWEVER...BOTH MODEL/S DEPICT PCPN AROUND THE ASSOCIATED COLD
FRONT...AND SOUNDINGS SUGGEST IT WILL BE COLD ENOUGH THAT SNOW WILL
BE THE DOMINANT PCPN TYPE. ENOUGH VARIABILITY IN THE MODELS THAT A
WINTRY MIX...AT LEAST FOR THE SOUTHERN 1/3...CAN/T BE RULED OUT.
CURRENT SCENARIO WOULD FAVOR A FEW INCHES OF SNOW
ACCUMULATION...MOSTLY NORTH OF THE I-94 CORRIDOR.
BOTH THE GFS/EC DEPICT HIGH PRESSURE FOR TUE NIGHT/WED...AND THEN
START TO STRAY FROM EACH OTHER AFTER THAT. THE EC WOULD KEEP THINGS
RATHER BENIGN FOR THE FORECAST AREA...WITH A RIDGE OF HIGH PRESSURE
OVERHEAD. THE GFS WOULD DRIVE AN UPPER LEVEL SHORTWAVE TROUGH FROM
THE WEST COAST TO ACROSS THE UPPER MISSISSIPPI RIVER VALLEY FOR FRI.
PLENTY OF VARIABILITY WITHIN THE GFS ON THIS THOUGH. WILL HANG WITH
AN EC/CONSENSUS SOLUTION FOR THIS TIME PERIOD.
&&
.AVIATION...THROUGH 18Z SATURDAY
1219 PM CDT FRI MAR 15 2013
THE FIRST SHORT WAVE TROUGH IS MOVING PAST THE REGION AND TAKING
ITS PRECIPITATION SHIELD WITH IT. WILL NOT INCLUDE ANY
PRECIPITATION FROM THIS WAVE AT KRST AND ONLY FOR AN HOUR AT KLSE.
ONCE THE PRECIPITATION ENDS...CONDITIONS REMAIN IFR AS ENOUGH FOG
IS KEEPING THE VISIBILITY BELOW 3 MILES WITH CEILINGS AT OR BELOW
1K FEET. THE NEXT SHORT WAVE TROUGH IS MOVING INTO NORTH DAKOTA
WITH THE NEXT ROUND OF PRECIPITATION. EXPECT THIS SYSTEM WILL
QUICKLY DROP SOUTHEAST AND START SPREADING PRECIPITATION BACK IN
EARLY THIS EVENING. INITIALLY EXPECTING THIS TO START OUT AS A
RAIN/SNOW MIX BEFORE GOING TO ALL SNOW. THE 15.15Z RAP CONTINUES
TO SUGGEST THE POTENTIAL FOR A LOSS OF ICE IN THE CLOUDS AS THE
PRECIPITATION ENDS. WILL INCLUDE A PERIOD OF A FREEZING
DRIZZLE/SNOW MIX AT THE TAIL END...BUT THERE IS ALSO THE
POSSIBILITY THAT THE PRECIPITATION COULD HAVE ENDED BY THE TIME
THE LOSS OF ICE OCCURS. ONCE THE PRECIPITATION ENDS...SHOULD SEE
THE VISIBILITY IMPROVE TO MVFR WHILE THE CEILINGS WILL EITHER BE
MVFR OR IFR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
300 AM CDT FRI MAR 15 2013
WI...WINTER WEATHER ADVISORY FROM 6 AM TODAY TO 1 AM CDT SATURDAY
FOR WIZ017-029-032>034-041>044-053-055.
MN...WINTER WEATHER ADVISORY FROM 6 AM TODAY TO 1 AM CDT SATURDAY
FOR MNZ079-086>088-096.
IA...NONE.
&&
$$
SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION...04
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1202 PM MDT FRI MAR 15 2013
.AVIATION...18Z TAF ISSUANCE...
VFR CONDITIONS THROUGH THE TAF PERIOD. WEST-TO-NORTHWEST WINDS
WILL BE BREEZY THIS AFTERNOON WITH OCCASIONAL GUSTS TO 25-30 KTS.
A WEAK FRONT WILL MOVE ACROSS THE PLAINS OVERNIGHT WITH WEAK
NORTHEASTERLY WINDS BEHIND IT. VFR CIGS WITH BASES 5-10 KFT AGL
WILL BE PREVALENT ACROSS THE PANHANDLE AFTER AROUND 06Z SAT.
SCATTERED SHOWERS WILL ALSO BE POSSIBLE OVER MAINLY THE PANHANDLE
BY SAT MORNING.
&&
PREV DISCUSSION... /ISSUED 320 AM MDT FRI MAR 15 2013/
SHORT TERM...TODAY THROUGH SUNDAY...
WATER VAPOR SATELLITE AND RUC UPPER AIR ANALYSIS SHOWED A RIDGE
AXIS FROM THE DESERT SOUTHWEST TO THE NORTHERN ROCKIES. ABUNDANT
UPPER LEVEL PACIFIC MOISTURE WAS STREAMING EASTWARD OVER THE
REGION. INFRARED SATELLITE IMAGERY AND SURFACE OBSERVATIONS
INDICATED CLOUD CEILINGS ABOVE 12000 FT AGL. A STATIONARY FRONT
WAS LOCATED FROM CENTRAL MONTANA TO NORTHERN SOUTH DAKOTA...WITH
A WEAK TROUGH FROM WESTERN NEBRASKA TO NORTHWEST KANSAS. A RIDGE
OF HIGH PRESSURE EXTENDED FROM WESTERN WYOMING TO THE FOUR CORNERS
REGION. WEST TO NORTHWEST 700MB WINDS 30 TO 40 KT AND 850-700MB
GRADIENT WERE GENERATING GUSTY WESTERLY WINDS ACROSS THE WIND
PRONE AREAS OF SOUTHEAST WYOMING. GUSTS OF 45 TO 50 MPH WERE
REPORTED AT ARLINGTON. TEMPERATURES RANGED FROM THE UPPER 30S TO
LOWER 50S.
FORECAST CHALLENGES DURING THE SHORT TERM INCLUDE NEAR RECORD
WARMTH TODAY FOR THE PLAINS...PRECIPITATION CHANCES THIS WEEKEND...
AND POTENTIAL FOR HIGH WINDS ON SUNDAY.
THE 00Z MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THE OVERALL
LARGE SCALE PATTERN. THE UPPER RIDGE FLATTENS WITH ZONAL FLOW
ALOFT ACROSS THE REGION TODAY AND TONIGHT. SHORTWAVE ENERGY
MOVING SOUTHEAST ACROSS MONTANA AND THE DAKOTAS AND SURFACE
RIDGING TO THE NORTHEAST WILL PUSH A BACKDOOR FRONT INTO EASTERN
WYOMING AND NORTHEAST COLORADO TONIGHT. BEFORE THE FRONT ARRIVES...
IT WILL BE ANOTHER WARM AFTERNOON FOR THE PLAINS AS 700MB
TEMPERATURES RISE TO NEAR 3C. HIGHS TODAY WILL BE SIMILAR TO
YESTERDAY WITH 60S TO MID 70S. HERE ARE THE RECORD HIGH
TEMPERATURES FOR MARCH 15...
CHEYENNE...67 (1877)
RAWLINS...60 (2012)
TORRINGTON...73 (2012)
ALLIANCE...74 (1999)
SCOTTSBLUFF...75 (2012)
SIDNEY...75 (1999)
LIGHT RAIN AND SNOW SHOWERS DEVELOP TONIGHT AND CONTINUE SATURDAY
IN WEAK POST FRONTAL UPSLOPE FLOW. SNOW ACCUMULATIONS OVER THE
HIGHER ELEVATIONS WILL BE AROUND AN INCH. IT WILL BE NOTICEABLY
COOLER SATURDAY WITH 700MB TEMPERATURES AROUND -5C. EXPECT HIGHS
IN THE 40S AND 50S. PRECIPITATION DECREASES IN AREAL COVERAGE
SATURDAY NIGHT WITH THE DEPARTURE OF THE UPPER LEVEL SHORTWAVE.
THE FRONT BECOMES REORIENTED ALONG THE FRONT RANGE SATURDAY NIGHT.
THE LOW LEVEL PRESSURE GRADIENT TIGHTENS SATURDAY NIGHT IN ADVANCE
OF THE NEXT PACIFIC SHORTWAVE TROUGH.
THIS SHORTWAVE TROUGH WILL MOVE SOUTHEAST ACROSS WYOMING SUNDAY.
AHEAD OF THE SHORTWAVE...RAPID CYCLOGENESIS WILL OCCUR ALONG A
QUASI-STATIONARY FRONTAL BOUNDARY SITUATED ALONG THE FRONT RANGE.
THIS WILL STRENGTHEN THE PRESSURE GRADIENT ALONG THE LARAMIE
RANGE...INCREASING WESTERLY WINDS ACROSS SOUTHEAST WYOMING. DEEP
LAYER UNIDIRECTIONAL FLOW WITH LOW LEVEL WINDS OF 45 TO 55 KT
COMBINED WITH THE PASSING SHORTWAVE TROUGH SHOULD TRANSPORT THE
STRONG WINDS TO THE SURFACE ACROSS SOUTHEAST WYOMING. LARGE
PRESSURE RISES SPREAD FROM SOUTHEAST WYOMING INTO THE NEBRASKA
PANHANDLE BY SUNDAY EVENING. CONFIDENCE IS INCREASING FOR THE
POTENTIAL OF A BORA WIND EVENT ACROSS MUCH OF THE FORECAST AREA
SUNDAY.
A COUPLE OF COLD FRONTS WILL MOVE ACROSS THE REGION WITH THIS
SYSTEM AS WELL. SYNOPTIC SCALE LIFT ASSOCIATED WITH THE SHORTWAVE...
WESTERLY UPSLOPE FLOW...AND THE FRONTAL PASSAGES WILL YIELD
CHANCES FOR RAIN SHOWERS AND HIGH ELEVATION SNOW SHOWERS SUNDAY.
DOWNSLOPE WESTERLY FLOW IN THE LOWER LEVELS WILL BRING MILDER
TEMPERATURES FOR THE PLAINS SUNDAY...WITH COOLER TEMPERATURES
OUT WEST.
LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...
SUNDAY NIGHT...PROGRESSIVE FAST MOVING SHORTWAVE TROUGH ALOFT
MOVES FROM EASTERN WYOMING TO EASTERN NEBRASKA WITH FAST NORTHWEST
FLOW IN ITS WAKE. ASSOCIATED COLD FRONT MOVES QUICKLY EASTWARD
FROM WESTERN NEBRASKA EARLY IN THE EVENING WITH STRONG COLD AIR
ADVECTION ACROSS OUR COUNTIES. QUITE WINDY BASED ON PROGGED LOW
AND MID LEVEL GRADIENTS...STRONG UNIDIRECTIONAL NORTHWEST WINDS
AND STRENGTH OF THICKNESS PACKING AND COLD AIR ADVECTION.
DECREASING COVERAGE OF PRECIPITATION OVERNIGHT IN THE WAKE OF THE
SHORTWAVE TROUGH ALOFT AND WITH STRONG DOWNSLOPING AND RAIN
SHADOWING EFFECT DOWNWIND OF THE LARAMIE RANGE.
MONDAY...WINDY AND RAW DAY WITH STRONG NORTHWEST UNIDIRECTIONAL
FLOW FROM THE SURFACE THROUGH 500 MB AND PROGGED LOW AND MID LEVEL
GRADIENTS. COOLER MAXIMUM TEMPERATURES BASED ON PROJECTED
THICKNESSES AND 700 MB TEMPERATURES.
TUESDAY...ANOTHER WARMING TREND ENSUES AS HEIGHTS ALOFT RISE UNDER
ZONAL FLOW ALOFT...AND BASED ON PROJECTED THICKNESS AND 700 MB
TEMPERATURE CHANGES.
WEDNESDAY...15/00Z ECMWF LOOKS WAY TOO BULLISH WITH QPF BASED ON
ITS MESOSCALE AND SYNOPTIC PATTERN BRINGING IN THE NEXT SHORTWAVE
TROUGH ALOFT ACROSS WESTERN WYOMING. PREFER THE MORE BEARISH QPF
DEPICTION FROM THE 15/00Z GFS IN FAST ZONAL FLOW ALOFT...THUS WILL
PAINT LOW AFTERNOON POPS ACROSS OUR MOUNTAINS DUE TO
OROGRAPHICS...AND DRY ELSEWHERE.
THURSDAY...15/00Z ECMWF AND 15/00Z GFS DIFFER SLIGHTLY ON SHORTWAVE
TROUGH PROJECTION WITH THE ECMWF MORE PROGRESSIVE WITH THE TROUGH
OVER WYOMING...WHILE THE GFS HANGS BACK THE TROUGH AXIS OVER IDAHO.
IN EITHER EVENT HOWEVER...WILL SEE AT LEAST A SCATTERED COVERAGE OF
SHOWERS OF RAIN OR SNOW IN THE AFTERNOON.
FIRE WEATHER...
MUCH ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS WILL PREVAIL
TODAY WITH MINIMUM RELATIVE HUMIDITIES AROUND 20 PERCENT DURING
THE AFTERNOON. A TIGHT SURFACE PRESSURE GRADIENT WILL YIELD GUSTY
WESTERLY WINDS TODAY. A WEAK COLD FRONT WILL SINK SOUTH INTO
SOUTHEAST WYOMING AND THE NEBRASKA PANHANDLE THIS WEEKEND. UPSLOPE
FLOW AND MOISTURE WILL RESULT IN INCREASING CHANCES FOR RAIN AND
SNOW SHOWERS...ALONG WITH COOLER TEMPERATURES. THE BEST CHANCES
FOR MEASURABLE PRECIPITATION FOR THE PLAINS WILL BE TONIGHT
THROUGH SATURDAY NIGHT...AND ALONG AND WEST OF THE LARAMIE RANGE
SUNDAY. WINDS WILL BECOME QUITE STRONG AND GUSTY SUNDAY AS LOW
PRESSURE AND A STRONGER COLD FRONT PASS THROUGH THE DISTRICTS.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
AVIATION...FINCH
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
529 AM MDT FRI MAR 15 2013
.AVIATION...12Z TAFS. PERIODS OF SCATTERED TO BROKEN CLOUDS AT OR
ABOVE 5000 FEET AGL. AFTER 15Z...WINDS GUSTING TO 29 TO 32 KNOTS...
WITH WINDS DECREASING AFTER 01Z. RUBIN
&&
.PREV DISCUSSION... /ISSUED 320 AM MDT FRI MAR 15 2013/
SHORT TERM...TODAY THROUGH SUNDAY...
WATER VAPOR SATELLITE AND RUC UPPER AIR ANALYSIS SHOWED A RIDGE
AXIS FROM THE DESERT SOUTHWEST TO THE NORTHERN ROCKIES. ABUNDANT
UPPER LEVEL PACIFIC MOISTURE WAS STREAMING EASTWARD OVER THE
REGION. INFRARED SATELLITE IMAGERY AND SURFACE OBSERVATIONS
INDICATED CLOUD CEILINGS ABOVE 12000 FT AGL. A STATIONARY FRONT
WAS LOCATED FROM CENTRAL MONTANA TO NORTHERN SOUTH DAKOTA...WITH
A WEAK TROUGH FROM WESTERN NEBRASKA TO NORTHWEST KANSAS. A RIDGE
OF HIGH PRESSURE EXTENDED FROM WESTERN WYOMING TO THE FOUR CORNERS
REGION. WEST TO NORTHWEST 700MB WINDS 30 TO 40 KT AND 850-700MB
GRADIENT WERE GENERATING GUSTY WESTERLY WINDS ACROSS THE WIND
PRONE AREAS OF SOUTHEAST WYOMING. GUSTS OF 45 TO 50 MPH WERE
REPORTED AT ARLINGTON. TEMPERATURES RANGED FROM THE UPPER 30S TO
LOWER 50S.
FORECAST CHALLENGES DURING THE SHORT TERM INCLUDE NEAR RECORD
WARMTH TODAY FOR THE PLAINS...PRECIPITATION CHANCES THIS WEEKEND...
AND POTENTIAL FOR HIGH WINDS ON SUNDAY.
THE 00Z MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THE OVERALL
LARGE SCALE PATTERN. THE UPPER RIDGE FLATTENS WITH ZONAL FLOW
ALOFT ACROSS THE REGION TODAY AND TONIGHT. SHORTWAVE ENERGY
MOVING SOUTHEAST ACROSS MONTANA AND THE DAKOTAS AND SURFACE
RIDGING TO THE NORTHEAST WILL PUSH A BACKDOOR FRONT INTO EASTERN
WYOMING AND NORTHEAST COLORADO TONIGHT. BEFORE THE FRONT ARRIVES...
IT WILL BE ANOTHER WARM AFTERNOON FOR THE PLAINS AS 700MB
TEMPERATURES RISE TO NEAR 3C. HIGHS TODAY WILL BE SIMILAR TO
YESTERDAY WITH 60S TO MID 70S. HERE ARE THE RECORD HIGH
TEMPERATURES FOR MARCH 15...
CHEYENNE...67 (1877)
RAWLINS...60 (2012)
TORRINGTON...73 (2012)
ALLIANCE...74 (1999)
SCOTTSBLUFF...75 (2012)
SIDNEY...75 (1999)
LIGHT RAIN AND SNOW SHOWERS DEVELOP TONIGHT AND CONTINUE SATURDAY
IN WEAK POST FRONTAL UPSLOPE FLOW. SNOW ACCUMULATIONS OVER THE
HIGHER ELEVATIONS WILL BE AROUND AN INCH. IT WILL BE NOTICEABLY
COOLER SATURDAY WITH 700MB TEMPERATURES AROUND -5C. EXPECT HIGHS
IN THE 40S AND 50S. PRECIPITATION DECREASES IN AREAL COVERAGE
SATURDAY NIGHT WITH THE DEPARTURE OF THE UPPER LEVEL SHORTWAVE.
THE FRONT BECOMES REORIENTED ALONG THE FRONT RANGE SATURDAY NIGHT.
THE LOW LEVEL PRESSURE GRADIENT TIGHTENS SATURDAY NIGHT IN ADVANCE
OF THE NEXT PACIFIC SHORTWAVE TROUGH.
THIS SHORTWAVE TROUGH WILL MOVE SOUTHEAST ACROSS WYOMING SUNDAY.
AHEAD OF THE SHORTWAVE...RAPID CYCLOGENESIS WILL OCCUR ALONG A
QUASI-STATIONARY FRONTAL BOUNDARY SITUATED ALONG THE FRONT RANGE.
THIS WILL STRENGTHEN THE PRESSURE GRADIENT ALONG THE LARAMIE
RANGE...INCREASING WESTERLY WINDS ACROSS SOUTHEAST WYOMING. DEEP
LAYER UNIDIRECTIONAL FLOW WITH LOW LEVEL WINDS OF 45 TO 55 KT
COMBINED WITH THE PASSING SHORTWAVE TROUGH SHOULD TRANSPORT THE
STRONG WINDS TO THE SURFACE ACROSS SOUTHEAST WYOMING. LARGE
PRESSURE RISES SPREAD FROM SOUTHEAST WYOMING INTO THE NEBRASKA
PANHANDLE BY SUNDAY EVENING. CONFIDENCE IS INCREASING FOR THE
POTENTIAL OF A BORA WIND EVENT ACROSS MUCH OF THE FORECAST AREA
SUNDAY.
A COUPLE OF COLD FRONTS WILL MOVE ACROSS THE REGION WITH THIS
SYSTEM AS WELL. SYNOPTIC SCALE LIFT ASSOCIATED WITH THE SHORTWAVE...
WESTERLY UPSLOPE FLOW...AND THE FRONTAL PASSAGES WILL YIELD
CHANCES FOR RAIN SHOWERS AND HIGH ELEVATION SNOW SHOWERS SUNDAY.
DOWNSLOPE WESTERLY FLOW IN THE LOWER LEVELS WILL BRING MILDER
TEMPERATURES FOR THE PLAINS SUNDAY...WITH COOLER TEMPERATURES
OUT WEST.
LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...
SUNDAY NIGHT...PROGRESSIVE FAST MOVING SHORTWAVE TROUGH ALOFT
MOVES FROM EASTERN WYOMING TO EASTERN NEBRASKA WITH FAST NORTHWEST
FLOW IN ITS WAKE. ASSOCIATED COLD FRONT MOVES QUICKLY EASTWARD
FROM WESTERN NEBRASKA EARLY IN THE EVENING WITH STRONG COLD AIR
ADVECTION ACROSS OUR COUNTIES. QUITE WINDY BASED ON PROGGED LOW
AND MID LEVEL GRADIENTS...STRONG UNIDIRECTIONAL NORTHWEST WINDS
AND STRENGTH OF THICKNESS PACKING AND COLD AIR ADVECTION.
DECREASING COVERAGE OF PRECIPITATION OVERNIGHT IN THE WAKE OF THE
SHORTWAVE TROUGH ALOFT AND WITH STRONG DOWNSLOPING AND RAIN
SHADOWING EFFECT DOWNWIND OF THE LARAMIE RANGE.
MONDAY...WINDY AND RAW DAY WITH STRONG NORTHWEST UNIDIRECTIONAL
FLOW FROM THE SURFACE THROUGH 500 MB AND PROGGED LOW AND MID LEVEL
GRADIENTS. COOLER MAXIMUM TEMPERATURES BASED ON PROJECTED
THICKNESSES AND 700 MB TEMPERATURES.
TUESDAY...ANOTHER WARMING TREND ENSUES AS HEIGHTS ALOFT RISE UNDER
ZONAL FLOW ALOFT...AND BASED ON PROJECTED THICKNESS AND 700 MB
TEMPERATURE CHANGES.
WEDNESDAY...15/00Z ECMWF LOOKS WAY TOO BULLISH WITH QPF BASED ON
ITS MESOSCALE AND SYNOPTIC PATTERN BRINGING IN THE NEXT SHORTWAVE
TROUGH ALOFT ACROSS WESTERN WYOMING. PREFER THE MORE BEARISH QPF
DEPICTION FROM THE 15/00Z GFS IN FAST ZONAL FLOW ALOFT...THUS WILL
PAINT LOW AFTERNOON POPS ACROSS OUR MOUNTAINS DUE TO
OROGRAPHICS...AND DRY ELSEWHERE.
THURSDAY...15/00Z ECMWF AND 15/00Z GFS DIFFER SLIGHTLY ON SHORTWAVE
TROUGH PROJECTION WITH THE ECMWF MORE PROGRESSIVE WITH THE TROUGH
OVER WYOMING...WHILE THE GFS HANGS BACK THE TROUGH AXIS OVER IDAHO.
IN EITHER EVENT HOWEVER...WILL SEE AT LEAST A SCATTERED COVERAGE OF
SHOWERS OF RAIN OR SNOW IN THE AFTERNOON.
AVIATION...06Z TAFS. VFR THROUGH PERIOD. SCATTERED TO BROKEN CLOUDS
AT OR ABOVE 8000 FEET AGL. 16Z TO 02Z...WINDS GUSTING 25 TO 32 KT.
A WEAK SURFACE COLD FRONT OR PREFRONTAL TROUGH PASSES THE AERODROMES
LATE FRIDAY MORNING AND EARLY AFTERNOON WITH WINDS VEERING TO NORTH
AND NORTHWEST.
FIRE WEATHER...
MUCH ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS WILL PREVAIL
TODAY WITH MINIMUM RELATIVE HUMIDITIES AROUND 20 PERCENT DURING
THE AFTERNOON. A TIGHT SURFACE PRESSURE GRADIENT WILL YIELD GUSTY
WESTERLY WINDS TODAY. A WEAK COLD FRONT WILL SINK SOUTH INTO
SOUTHEAST WYOMING AND THE NEBRASKA PANHANDLE THIS WEEKEND. UPSLOPE
FLOW AND MOISTURE WILL RESULT IN INCREASING CHANCES FOR RAIN AND
SNOW SHOWERS...ALONG WITH COOLER TEMPERATURES. THE BEST CHANCES
FOR MEASURABLE PRECIPITATION FOR THE PLAINS WILL BE TONIGHT
THROUGH SATURDAY NIGHT...AND ALONG AND WEST OF THE LARAMIE RANGE
SUNDAY. WINDS WILL BECOME QUITE STRONG AND GUSTY SUNDAY AS LOW
PRESSURE AND A STRONGER COLD FRONT PASS THROUGH THE DISTRICTS.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...JAMSKI
LONG TERM/AVIATION...RUBIN
AREA FORECAST DISCUSSION...CORRECTED
NWS CHEYENNE WY
320 AM MDT FRI MAR 15 2013
.SHORT TERM...TODAY THROUGH SUNDAY...
WATER VAPOR SATELLITE AND RUC UPPER AIR ANALYSIS SHOWED A RIDGE
AXIS FROM THE DESERT SOUTHWEST TO THE NORTHERN ROCKIES. ABUNDANT
UPPER LEVEL PACIFIC MOISTURE WAS STREAMING EASTWARD OVER THE
REGION. INFRARED SATELLITE IMAGERY AND SURFACE OBSERVATIONS
INDICATED CLOUD CEILINGS ABOVE 12000 FT AGL. A STATIONARY FRONT
WAS LOCATED FROM CENTRAL MONTANA TO NORTHERN SOUTH DAKOTA...WITH
A WEAK TROUGH FROM WESTERN NEBRASKA TO NORTHWEST KANSAS. A RIDGE
OF HIGH PRESSURE EXTENDED FROM WESTERN WYOMING TO THE FOUR CORNERS
REGION. WEST TO NORTHWEST 700MB WINDS 30 TO 40 KT AND 850-700MB
GRADIENT WERE GENERATING GUSTY WESTERLY WINDS ACROSS THE WIND
PRONE AREAS OF SOUTHEAST WYOMING. GUSTS OF 45 TO 50 MPH WERE
REPORTED AT ARLINGTON. TEMPERATURES RANGED FROM THE UPPER 30S TO
LOWER 50S.
FORECAST CHALLENGES DURING THE SHORT TERM INCLUDE NEAR RECORD
WARMTH TODAY FOR THE PLAINS...PRECIPITATION CHANCES THIS WEEKEND...
AND POTENTIAL FOR HIGH WINDS ON SUNDAY.
THE 00Z MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THE OVERALL
LARGE SCALE PATTERN. THE UPPER RIDGE FLATTENS WITH ZONAL FLOW
ALOFT ACROSS THE REGION TODAY AND TONIGHT. SHORTWAVE ENERGY
MOVING SOUTHEAST ACROSS MONTANA AND THE DAKOTAS AND SURFACE
RIDGING TO THE NORTHEAST WILL PUSH A BACKDOOR FRONT INTO EASTERN
WYOMING AND NORTHEAST COLORADO TONIGHT. BEFORE THE FRONT ARRIVES...
IT WILL BE ANOTHER WARM AFTERNOON FOR THE PLAINS AS 700MB
TEMPERATURES RISE TO NEAR 3C. HIGHS TODAY WILL BE SIMILAR TO
YESTERDAY WITH 60S TO MID 70S. HERE ARE THE RECORD HIGH
TEMPERATURES FOR MARCH 15...
CHEYENNE...67 (1877)
RAWLINS...60 (2012)
TORRINGTON...73 (2012)
ALLIANCE...74 (1999)
SCOTTSBLUFF...75 (2012)
SIDNEY...75 (1999)
LIGHT RAIN AND SNOW SHOWERS DEVELOP TONIGHT AND CONTINUE SATURDAY
IN WEAK POST FRONTAL UPSLOPE FLOW. SNOW ACCUMULATIONS OVER THE
HIGHER ELEVATIONS WILL BE AROUND AN INCH. IT WILL BE NOTICEABLY
COOLER SATURDAY WITH 700MB TEMPERATURES AROUND -5C. EXPECT HIGHS
IN THE 40S AND 50S. PRECIPITATION DECREASES IN AREAL COVERAGE
SATURDAY NIGHT WITH THE DEPARTURE OF THE UPPER LEVEL SHORTWAVE.
THE FRONT BECOMES REORIENTED ALONG THE FRONT RANGE SATURDAY NIGHT.
THE LOW LEVEL PRESSURE GRADIENT TIGHTENS SATURDAY NIGHT IN ADVANCE
OF THE NEXT PACIFIC SHORTWAVE TROUGH.
THIS SHORTWAVE TROUGH WILL MOVE SOUTHEAST ACROSS WYOMING SUNDAY.
AHEAD OF THE SHORTWAVE...RAPID CYCLOGENESIS WILL OCCUR ALONG A
QUASI-STATIONARY FRONTAL BOUNDARY SITUATED ALONG THE FRONT RANGE.
THIS WILL STRENGTHEN THE PRESSURE GRADIENT ALONG THE LARAMIE
RANGE...INCREASING WESTERLY WINDS ACROSS SOUTHEAST WYOMING. DEEP
LAYER UNIDIRECTIONAL FLOW WITH LOW LEVEL WINDS OF 45 TO 55 KT
COMBINED WITH THE PASSING SHORTWAVE TROUGH SHOULD TRANSPORT THE
STRONG WINDS TO THE SURFACE ACROSS SOUTHEAST WYOMING. LARGE
PRESSURE RISES SPREAD FROM SOUTHEAST WYOMING INTO THE NEBRASKA
PANHANDLE BY SUNDAY EVENING. CONFIDENCE IS INCREASING FOR THE
POTENTIAL OF A BORA WIND EVENT ACROSS MUCH OF THE FORECAST AREA
SUNDAY.
A COUPLE OF COLD FRONTS WILL MOVE ACROSS THE REGION WITH THIS
SYSTEM AS WELL. SYNOPTIC SCALE LIFT ASSOCIATED WITH THE SHORTWAVE...
WESTERLY UPSLOPE FLOW...AND THE FRONTAL PASSAGES WILL YIELD
CHANCES FOR RAIN SHOWERS AND HIGH ELEVATION SNOW SHOWERS SUNDAY.
DOWNSLOPE WESTERLY FLOW IN THE LOWER LEVELS WILL BRING MILDER
TEMPERATURES FOR THE PLAINS SUNDAY...WITH COOLER TEMPERATURES
OUT WEST.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...
SUNDAY NIGHT...PROGRESSIVE FAST MOVING SHORTWAVE TROUGH ALOFT
MOVES FROM EASTERN WYOMING TO EASTERN NEBRASKA WITH FAST NORTHWEST
FLOW IN ITS WAKE. ASSOCIATED COLD FRONT MOVES QUICKLY EASTWARD
FROM WESTERN NEBRASKA EARLY IN THE EVENING WITH STRONG COLD AIR
ADVECTION ACROSS OUR COUNTIES. QUITE WINDY BASED ON PROGGED LOW
AND MID LEVEL GRADIENTS...STRONG UNIDIRECTIONAL NORTHWEST WINDS
AND STRENGTH OF THICKNESS PACKING AND COLD AIR ADVECTION.
DECREASING COVERAGE OF PRECIPITATION OVERNIGHT IN THE WAKE OF THE
SHORTWAVE TROUGH ALOFT AND WITH STRONG DOWNSLOPING AND RAIN
SHADOWING EFFECT DOWNWIND OF THE LARAMIE RANGE.
MONDAY...WINDY AND RAW DAY WITH STRONG NORTHWEST UNIDIRECTIONAL
FLOW FROM THE SURFACE THROUGH 500 MB AND PROGGED LOW AND MID LEVEL
GRADIENTS. COOLER MAXIMUM TEMPERATURES BASED ON PROJECTED
THICKNESSES AND 700 MB TEMPERATURES.
TUESDAY...ANOTHER WARMING TREND ENSUES AS HEIGHTS ALOFT RISE UNDER
ZONAL FLOW ALOFT...AND BASED ON PROJECTED THICKNESS AND 700 MB
TEMPERATURE CHANGES.
WEDNESDAY...15/00Z ECMWF LOOKS WAY TOO BULLISH WITH QPF BASED ON
ITS MESOSCALE AND SYNOPTIC PATTERN BRINGING IN THE NEXT SHORTWAVE
TROUGH ALOFT ACROSS WESTERN WYOMING. PREFER THE MORE BEARISH QPF
DEPICTION FROM THE 15/00Z GFS IN FAST ZONAL FLOW ALOFT...THUS WILL
PAINT LOW AFTERNOON POPS ACROSS OUR MOUNTAINS DUE TO
OROGRAPHICS...AND DRY ELSEWHERE.
THURSDAY...15/00Z ECMWF AND 15/00Z GFS DIFFER SLIGHTLY ON SHORTWAVE
TROUGH PROJECTION WITH THE ECMWF MORE PROGRESSIVE WITH THE TROUGH
OVER WYOMING...WHILE THE GFS HANGS BACK THE TROUGH AXIS OVER IDAHO.
IN EITHER EVENT HOWEVER...WILL SEE AT LEAST A SCATTERED COVERAGE OF
SHOWERS OF RAIN OR SNOW IN THE AFTERNOON.
&&
.AVIATION...06Z TAFS. VFR THROUGH PERIOD. SCATTERED TO BROKEN CLOUDS
AT OR ABOVE 8000 FEET AGL. 16Z TO 02Z...WINDS GUSTING 25 TO 32 KT.
A WEAK SURFACE COLD FRONT OR PREFRONTAL TROUGH PASSES THE AERODROMES
LATE FRIDAY MORNING AND EARLY AFTERNOON WITH WINDS VEERING TO NORTH
AND NORTHWEST.
&&
.FIRE WEATHER...
MUCH ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS WILL PREVAIL
TODAY WITH MINIMUM RELATIVE HUMIDITIES AROUND 20 PERCENT DURING
THE AFTERNOON. A TIGHT SURFACE PRESSURE GRADIENT WILL YIELD GUSTY
WESTERLY WINDS TODAY. A WEAK COLD FRONT WILL SINK SOUTH INTO
SOUTHEAST WYOMING AND THE NEBRASKA PANHANDLE THIS WEEKEND. UPSLOPE
FLOW AND MOISTURE WILL RESULT IN INCREASING CHANCES FOR RAIN AND
SNOW SHOWERS...ALONG WITH COOLER TEMPERATURES. THE BEST CHANCES
FOR MEASURABLE PRECIPITATION FOR THE PLAINS WILL BE TONIGHT
THROUGH SATURDAY NIGHT...AND ALONG AND WEST OF THE LARAMIE RANGE
SUNDAY. WINDS WILL BECOME QUITE STRONG AND GUSTY SUNDAY AS LOW
PRESSURE AND A STRONGER COLD FRONT PASS THROUGH THE DISTRICTS.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...JAMSKI
LONG TERM/AVIATION...RUBIN
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
259 AM EDT SUN MAR 17 2013
.PREV DISCUSSION... /ISSUED 945 PM EDT SAT MAR 16 2013/
UPDATE...
HAVE MADE SEVERAL MINOR TWEAKS TO THE FORECAST...MAINLY TO SKY
COVER AS PART OF THE 00Z TAF ISSUANCE. BOTH HRRR AND LOCAL WRF
KEEP ALL RAIN NORTH OF THE AREA TONIGHT SO REMOVED POPS FROM
EXTREME NORTH GEORGIA AND ADDED A LITTLE FOG WORDING IN AS
WELL...WITH LOW CLOUDS MOVING IN SUNDAY MORNING EXPECT SOME PATCHY
FOG TO DEVELOP. NO MAJOR CHANGE TO TEMPS EXCEPT FOR MINOR TWEAKS
TO UPDATE FOR TRENDS. UPDATED PRODUCTS WILL BE OUT SHORTLY.
TDP
PREV DISCUSSION... /ISSUED 833 PM EDT SAT MAR 16 2013/
PREV DISCUSSION... /ISSUED 340 PM EDT SAT MAR 16 2013/
SHORT TERM /TONIGHT THROUGH SUNDAY/...
CURRENT SATELLITE LOOP SHOWS MOSTLY CLEAR SKIES ACROSS NORTH AND
CENTRAL GEORGIA. SURFACE HIGH PRESSURE WILL CONTINUE TO PERSIST
THROUGH THE WEEKEND...WITH WARMING ABOVE NORMAL TEMPERATURES
CONTINUING TODAY AND SUNDAY. EXPECT HIGH TEMPERATURES IN THE LOW TO
MID 70S...AND LOWS IN THE UPPER 40S AND LOW 50S. THE MODELS ARE IN
DECENT AGREEMENT AND FAIRLY CONSISTENT WITH WEAK FRONTAL BOUNDARY
SAGGING INTO THE TENNESSEE VALLEY TODAY. THIS FRONTAL BOUNDARY
SHOULD INCREASE CLOUD COVER ESPECIALLY ACROSS NORTH GA SUN AND MAY
EVEN SEE SOME ISOLATED SHOWERS SUN AFTERNOON ALSO. THE MODELS ARE
ALSO SHOWING A WEAK DISTURBANCE MOVING NORTHWARD INTO THE REGION
FROM THE GULF OF MEXICO WHICH WILL BRING ADDITIONAL MOISTURE INTO THE
AREA SUNDAY AFTERNOON INTO SUN NIGHT FOR NOW...HAVE INDICATED INCREASED
CLOUD COVER ACROSS CENTRAL GEORGIA AS A RESULT...AND ANY RESULTING
RAINFALL SHOULD STAY SOUTH OF THE CWA.
01
LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
WARM FRONT/STALLED FRONTAL BOUNDARY REMAINS ACROSS THE GA/TN BORDER
ON SUNDAY NIGHT. BOTH THE NAM AND GFS ARE PICKING UP ON A SHORTWAVE
MOVING NORTH IN THE SW FLOW FROM THE GULF OF MEXICO SUNDAY NIGHT.
BOTH MODELS PRODUCE PRECIP WITH THIS FEATURE...BUT THE NAM IS
FURTHER SOUTH WITH ITS BULLSEYE. WILL END UP ADDING SOME LOW END
CHANCE POPS FOR SHOWERS IN THE SW PORTION OF THE CWFA SUNDAY
EVENING.
A COLD FRONT IS STILL PROGGED TO MOVE THROUGH THE CWFA ON MONDAY
INTO EARLY TUESDAY. THE MAIN MID LEVEL FORCING WITH THIS SYSTEM
REMAINS WELL TO THE NORTH...BUT THERE WILL BE SOME LIFT/FORCING
ALONG THE FRONT. SURFACE INSTABILITY WILL SPREAD AHEAD OF THE FRONT
MONDAY AFTERNOON AND EVENING...ALONG WITH SOME DECENT SHEAR.
ISOLD/SCT SEVERE STORMS ARE POSSIBLE. BOTH THE NAM AND GFS ARE ALSO
SETTING UP A COOL AIR WEDGE ACROSS THE NE CWFA SUNDAY NIGHT INTO
MONDAY. AREAS IN THE WEDGE WILL STAY MORE STABLE. HOWEVER...ALONG
THE WEDGE FRONT...LOCALIZED HIGH SRH MAY BE ENHANCED.
THE COLD FRONT MAY HANG UP ACROSS THE SOUTHERN CWFA...BUT SHOULD
CLEAR THE AREA BY EARLY TUESDAY MORNING. HAVE TRIED TO ARRANGE POPS
ACCORDINGLY.
MID LEVEL FLOW REMAINS ZONAL FOR THE REMAINDER OF THE LONG TERM
PERIOD. SEVERAL FAST MOVING PIECES OF S/W ENERGY ARE PROGGED TO MOVE
THROUGH THE ATMOS...EACH TRIGGERING CLOUDS/SMALL POPS.
NLISTEMAA
&&
.AVIATION...
06Z UPDATE...
VFR CONDITIONS EXPECTED THROUGH 11-12Z THIS MORNING WHEN
ADDITIONAL MOISTURE IN THE AREA WILL RESULT IN BKN MVFR CIGS.
CONFIDENCE IN THESE CIG HEIGHTS IS LOW-MEDIUM AS LATEST MODELS
HAVE TRENDED TOWARDS KEEPING CIGS...IF ANY...TO LOW VFR. ANY CIGS
THAT DO DEVELOP ARE EXPECTED TO LIFT BY LATE MORNING. CIGS WILL
ONCE AGAIN DROP SUNDAY NIGHT...WITH MVFR EXPECTED. WINDS WILL BE
SW WINDS AT 7-10KT EXPECTED TODAY...WITH SHIFT TO THE SOUTH AND
POSSIBLY SSE AT 4-6KT AFTER 02-03Z MONDAY.
//ATL CONFIDENCE...06Z UPDATE...
LOW TO MEDIUM CONFIDENCE ON CIGS 12-15Z.
HIGH CONFIDENCE ON ALL OTHER ELEMENTS.
31
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 77 55 72 49 / 20 30 50 60
ATLANTA 73 58 71 49 / 20 30 60 60
BLAIRSVILLE 70 51 62 44 / 20 30 70 60
CARTERSVILLE 74 55 71 48 / 20 30 70 60
COLUMBUS 76 59 75 54 / 10 30 50 60
GAINESVILLE 73 55 66 48 / 20 30 60 60
MACON 76 55 74 53 / 10 30 50 60
ROME 74 56 71 48 / 20 40 70 50
PEACHTREE CITY 74 54 72 50 / 10 30 60 60
VIDALIA 78 55 78 58 / 10 20 40 60
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...31
LONG TERM....ARG
AVIATION...31
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
405 AM CDT SUN MAR 17 2013
.DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* HIGH END MVFR CIGS SCATTERING NEXT HOUR OR SO.
* MVFR CIGS LIKELY RETURNING FOR A FEW HOURS MID/LATE MORNING.
* NORTH WINDS TURN NORTHEAST THROUGH MID MORNING...THEN EAST-
SOUTHEAST LATE THIS AFTERNOON/EARLY THIS EVENING.
MDB
//DISCUSSION...UPDATED 09Z...
EDGE OF HIGH END MVFR CIGS JUST NOW CROSSING THE NORTHERN CHICAGO
METRO AND EXPECT IT TO WORK SOUTHWARD ACROSS THE CHI TERMINALS IN
THE NEXT HOUR OR SO. CHANCE FOR MVFR LAKE EFFECT CIGS TO RETURN
STILL ON TRACK FROM MID MORNING ONWARD AS FLOW TURNS
NORTHEASTERLY.
MDB
FROM 06Z...
HIGH PRESSURE IS SPREADING SOUTHWARD INTO THE UPPER MISSISSIPPI
RIVER VALLEY AND NORTHERN PLAINS EARLY TONIGHT WHILE A WEAK LOW
PRESSURE SYSTEM MOVES ACROSS LAKE HURON. WINDS WILL TURN TO THE
NORTH THEN NORTHEAST THROUGH MID/LATE MORNING AND EVENTUALLY TURN
TO THE EAST-SOUTHEAST LATE THIS AFTERNOON AND EARLY THIS EVENING
AS THE HIGH CROSSES LAKE MICHIGAN. MVFR CIGS CONTINUE ACROSS THE
TERMINALS BUT SCATTERING/CLEARING IS SPREADING SOUTHEASTWARD
TOWARDS THE AREA SO EXPECT THAT SKIES WILL SCATTER IN THE NEXT FEW
HOURS. GYY WILL BE THE WILDCARD AS FLOW WILL CONTINUE DOWN LAKE
MICHIGAN WHICH MAY KEEP BKN-OVC MVFR CIGS IN PLACE CONTINUOUSLY
THROUGH MIDDAY. MVFR LAKE CLOUDS HAVE A GOOD CHANCE OF RETURNING
TO ORD/MDW/DPA AS WELL DURING THE MID MORNING HOURS. SOME FLURRIES
ARE A POSSIBILITY UNDER ANY LAKE CLOUD COVER. LAKE PARAMETERS
BECOME LESS FAVORABLE DURING THE AFTERNOON SO EXPECT A DECREASE IN
CLOUD COVERAGE DURING THAT TIME. VFR WILL THEN PREVAIL INTO EARLY
MONDAY BUT AN APPROACHING SYSTEM WILL SPREAD MVFR CIGS BACK INTO
THE AREA TOWARD DAYBREAK ALONG WITH A CHANCE FOR SOME MIXED
PRECIPITATION BY MID MORNING MONDAY.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* MEDIUM-HIGH CONFIDENCE IN CLOUD COVERAGE TRENDS/TIMING.
* HIGH CONFIDENCE IN WIND TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...MIX OF SN/RA...PSBLY FZRA EARLY. MVFR LIKELY IFR
POSSIBLE.
TUESDAY THROUGH FRIDAY...MAINLY VFR.
RATZER
&&
.MARINE...
324 AM CDT
HIGH PRESSURE IS MOVING SOUTHEASTWARD TOWARD THE WESTERN GREAT LAKES
THIS MORNING WHILE A WEAK SURFACE LOW MOVES ACROSS EASTERN ONTARIO.
A TIGHT PRESSURE GRADIENT IS IN PLACE BETWEEN THESE TWO SYSTEMS WITH
STRONG NORTH-NORTHWEST WINDS BLOWING ACROSS MUCH OF THE CENTRAL AND
NORTHERN SECTIONS OF LAKE MICHIGAN. WINDS WILL DIMINISH THROUGH THE
MORNING ACROSS MOST OF THE LAKE AS THE HIGH MOVES OVERHEAD BUT THERE
WILL BE ENOUGH OF A PRESSURE GRADIENT IN PLACE TO THE SOUTH OF THE
HIGH OR ACROSS SOUTHERN LAKE MICHIGAN TO KEEP SLIGHTLY HIGHER WIND
SPEEDS GOING. WIND DIRECTION WILL SHIFT FROM NORTH-NORTHWEST TO EAST
THEN SOUTHEAST INTO THIS EVENING. SPEEDS WILL THEN INCREASE ACROSS
THE LAKE THIS EVENING AS THE HIGH DEPARTS TO THE EAST AND SURFACE
LOW PRESSURE MOVES EASTWARD ACROSS THE DAKOTAS AND ACROSS LAKE
SUPERIOR AND THE U.P. OF MICHIGAN BY MONDAY NIGHT. WILL GO AHEAD AND
EXTEND THE SMALL CRAFT FOR THE INDIANA NEARSHORE WATERS THROUGH LATE
AFTERNOON TODAY WITH WAVES EXPECTED TO STAY UP WITH THE NORTH TO
NORTHEAST WINDS. WILL ALSO ISSUE A SMALL CRAFT FOR THE ILLINOIS
NEARSHORE WATERS AS THE LONG FETCH OF NORTH THEN NORTHEAST WINDS
WILL BUILD WAVES THIS MORNING. WAVES WILL SUBSIDE LATER IN THE
AFTERNOON BUT WINDS WILL PICK UP TO SMALL CRAFT ADVISORY THRESHOLDS
DURING THE MID OR LATE EVENING WITH WAVES AGAIN BUILDING. WITH THIS
IN MIND WILL RUN THE SMALL CRAFT OUT THROUGH MONDAY MORNING THOUGH
THERE COULD BE A SHORT PERIOD WHERE WAVES FALL BELOW CRITERIA LATE
TODAY AND BEFORE WINDS COME UP ABOVE CRITERIA THIS EVENING.
A FURTHER SHIFT TO SOUTHWEST THEN WEST WINDS WILL OCCUR MONDAY
EVENING. COLDER AIR WILL SPREAD IN INTO TUESDAY AS THE LOW PASSES
AND THE PRESSURE GRADIENT WILL FURTHER STRENGTHEN LEADING TO A
PERIOD OF WEST TO NORTHWEST GALES...LIKELY IN THE 35-40 KT RANGE
STARTING MONDAY EVENING. RIGHT NOW MAINLY THE CENTRAL AND SOUTHERN
PORTIONS OF THE LAKE WILL SEE GALES WHILE THE FAR NORTH REMAINS
UNCERTAIN WITH THE EXPECTED TRACK OF THE LOW SHIFTING SLIGHTLY NORTH
AND SOUTH WITH RECENT FORECAST GUIDANCE. A FURTHER NORTH SOLUTION
WOULD RESULT IN A BETTER CHANCE OF THE NORTHERN THIRD SEEING GALES
AS WELL. SPEEDS WILL EASE LATER TUESDAY AFTERNOON BUT BE SLOW TO
REALLY QUIET DOWN THANKS TO THE LOW SLOWING AS IT PULLS OFF TO THE
EAST AND ANOTHER AREA OF HIGH PRESSURE NOSING INTO THE CENTRAL AND
NORTHERN PLAINS. THE FLOW THEN WEAKENS INTO FRIDAY WITH MAINLY A
NORTH TO NORTHEAST WIND EXPECTED THROUGH NEXT WEEKEND.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
335 AM CDT SUN MAR 17 2013
.SYNOPSIS...
ISSUED AT 335 AM CDT SUN MAR 17 2013
LATEST SFC ANALYSIS WAS INDICATING LARGE AND SEASONABLY STRONG RIDGE
COMPLEX ENGULFING MUCH OF THE UPPER MIDWEST WITH A NEAR 1030 MB
CENTER JUST NORTH OF THE NORTHWEST CORNER ON MN. SOUTHEAST RETURN
FLOW AND SFC PRESSURE GRADIENT TIGHTENING AND ORGANIZING ACRS THE
NORTHWESTERN HIGH PLAINS IN A REGION ALSO BATHED BY ROBUST PRESSURE
FALLS. ALOFT...WATER VAPOR IMAGERY WAS INDICATING A VIGOROUS UPPER
LEVEL WAVE ROLLING IN OFF THE PACIFIC AND ACRS OR/WA ATTM WITH AN
ASSOCIATED BAROCLINIC LEAF PLUME TO THE LEE OF IT ACRS THE WESTERN
ROCKIES. TO THE SOUTH ALONG TIGHTER LLVL BAROCLINIC RIBBON...AN
ISENTROPIC LIFT PRECIP EVENT WAS ONGOING ACRS KS...MO AND INTO
SOUTHERN IL.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 335 AM CDT SUN MAR 17 2013
TODAY...THE ABOVE MENTIONED STRONG RIDGE OF HIGH PRESSURE WILL LOOK
TO SQUEEZE EASTWARD ACRS THE WESTERN GRT LKS TODAY. AS IT DOES...
IT/S DRYING NORTHEAST TO EASTERLY FETCH IN THE BOUNDARY LAYER OR EVEN
DEEPER SHOULD KEEP MOST OF THE OVERRUNNING PRECIP OFF THE UPGLIDE
PROCESS TO THE SOUTH OF THE CWA. BUT WILL KEEP THE ONGOING MENTION
OF SPRINKLES OR A SLIGHT CHC OF LIGHT RAIN IN THE FAR SOUTH THIS
AFTERNOON. CLOUD COVER AND IT/S EFFECT ON TEMPS THE MAIN CHALLENGE
TODAY. THE RAP SEEMS TO HAVE SOME HANDEL ON CURRENT LLVL STRATUS
TRENDS PUSHING SOUTHWARD. AFTER MUCH OF THESE LOWER CLOUDS PUSH
ALMOST OUT OF THE DVN CWA...THE VEERING NORTHERLY FLOW SUGGESTED
BY THE RAP THEN SLOSHES BACK SOME LOWER LEVEL STRATUS BACK ACRS
MUCH OF THE DVN CWA FROM THE EAST AND NORTHEAST THIS MORNING UNDER
THE ONGOING AND SUBSTANTIAL TRAPPING INVERSION BASED AT H85 TO H75
MB. WITH PLUME OF MID AND UPPER LEVEL CLOUDS STREAMING OFF THE
OVERRUNNING PRECIP AND CONVECTION ACRS KS INTO MO...WITH THE CHANCE
OF THE STRATUS COMING BACK WILL KEEP THE FLAVOR OF THE DAY MOSTLY
CLOUDY ALTHOUGH SOME PEAKS OF SUN AT TIMES PROBABLE NORTH OF I80.
WILL KEEP HIGH TEMPS MAINLY IN THE 30S FOR A CHILLY ST PATRICK/S
DAY...BUT AREAS ALONG AND SOUTH OF I80 MAY GET NEAR 40 WITH SOME
CLOUD THINNING AT TIMES.
TONIGHT...THE DVN CWA TO BE MAINLY IN BETWEEN TWO LIFTING/FORCING
PROCESSES FOR MUCH OF THE NIGHT. THE ABOVE MENTIONED VIGOROUS UPPER
LEVEL WAVE CURRENTLY ACRS THE PACIFIC NORTHWEST WILL CONTINUE TO DIG
ACRS THE NORTHERN PLAINS AND MO RVR VALLEY THROUGH 12Z MON...WITH
UPPER LEVEL TROFFINESS EXTENDING ALL THE WAY DOWN INTO THE
SOUTHEASTERN PLAINS. CONCEPTUALLY THIS SHOULD ALLOW LLVL CYCLOGENESIS
BLOSSOM ACRS THE SOUTHEASTERN PLAINS AN UP THE LOWER TO MID MS RVR
VALLEY. NORTHWESTERN REACHING FLANK OF DEF ZONE PRECIP OFF THIS
FEATURE MAY CLIP THE SOUTHERN AND SOUTHEASTERN CWA THIS EVENING AND
INTO THE OVERNIGHT...BUT DRY LOW TO MID LEVELS WILL HAVE TO BE
OVERCOME. WILL KEEP CHC POPS IN THESE AREAS FOR LIGHT RAIN THIS
EVENING...BECOMING MIXED WITH SNOW OR SLEET INTO EARLY MON MORNING
AS EVAPO COOLING PROCESSES HAVE THEIR AFFECT. SFC TEMPS IN THESE
AREAS WILL BE MARGINAL FOR ANY FREEZING RAIN THREAT AND WILL NOT
MENTION. BUT THE MAIN FORCING EVENT IN VIEW OF THE APPROACHING
DIGGING WAVE WILL LOOK TO OCCUR ACRS THE NORTHEASTERN PLAINS INTO MN
AND IA LATER TONIGHT. DEEPENING SFC LOW PRESSURE TO UNDER 1000 MB TO
ROLL OUT OF THE DAKOTAS AND INTO NORTHWESTERN MN BY 12Z MON. THE
TROF ALMOST TAKING A NEG TILT AS IT DOES SUGGESTS A STRONGLY FORCED
EVENT ACRS THE UPPER MS RVR VALLEY REGION. ASSOCIATED PRECIP SWATH
AHEAD OF THIS PROCESS WILL LOOK TO PUSH ACRS IA AND INTO THE WESTERN/
NORTHWESTERN THIRD OF THE DVN CWA AFTER 08Z MON MORNING MAINLY IN
THE FORM OF SNOW. UPWARD VERTICAL VELOCITIES AND THERMODYNAMIC
PROFILES SUGGEST A BURST OF HEAVY WET SNOW POSSIBLE INTO THE FAR
NORTHWESTERN CWA WHERE UP TO AN INCH OF SNOW MAY OCCUR BY 12Z MON
NORTHWEST OF A CEDAR RAPIDS...TO MANCHESTER IA LINE. UP TO A HALF
INCH POSSIBLE ALONG AND NORTHWEST OF AN IOWA CITY...TO DYERSVILLE
LINE. STILL RATHER MILD SFC/GROUND TEMPS TO ACT AS AN ACCUMULATION
INHIBITOR AND PROMOTE COMPACTION AND MELTING EVENTUALLY. BUT SNOW
RATES BEFORE THE SUN RISES MAY STILL OVERCOME THIS FOR A WHILE TO
ALLOW THE POTENTIAL ACCUMS MENTIONED ABOVE. REST OF THE EVENT COVERED
IN DISCUSSION BELOW. ..12..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 17 2013
SNOW AMOUNTS MONDAY MORNING WILL BE THE MAIN CONCERN FOR THE LONG
TERM. AFTER MONDAY NORTHWEST FLOW TO DOMINATE THE REGION KEEPING
COLD AND DRY CONDITIONS OVER THE AREA INTO THE WEEKEND.
A SHORTWAVE OVER THE PACIFIC NORTHWEST EARLY THIS MORNING IS PROGGED
TO MOVE THROUGH THE MID AND UPPER MISSISSIPPI VALLEY MONDAY. THE
S/W WILL DRAG A STRONG COLD FRONT THROUGH THE REGION MONDAY
AFTERNOON AND EVENING WITH VERY COLD TEMPERATURES RUSHING INTO THE
REGION MONDAY AFTERNOON/NIGHT. THE FORECAST MODELS ARE IN GOOD
AGREEMENT IN SPREADING THE SYNOPTIC FORCING AHEAD OF THIS SYSTEM
OVER THE CWFA MONDAY MORNING WITH THE BETTER FORCING CLIPPING THE
NORTHERN COUNTIES. WITH PW/S EXPECTED TO BE AROUND A HALF INCH OR
SO QPF AMOUNTS OF 1 TO 2 TENTHS OF AN INCH LOOK REASONABLE BETWEEN
12Z AND 18Z. H8 TEMPS MONDAY MORNING WILL BE JUST BELOW ZERO
SUPPORTING SNOW RATIOS AROUND 10 TO 1 EARLY MONDAY MORNING WITH
RATIOS INCREASING TO 15 TO 1 BY LATE MORNING AS THE COLDER AIR
REACHES THE AREA. THE EXPECTED QPF AND SNOW RATIOS SUPPORT SNOWFALL
AMOUNTS IN THE 1 TO 2 INCH RANGE /STORM TOTAL/ NORTH OF I80 WITH THE
LOWER AMOUNTS NEAR I80 AND THE HIGHER AMOUNTS ALONG THE HIGHWAY 20
CORRIDOR. THE BIGGEST IMPACTS FROM THE SNOW MAY BE THE TIMING AND
LOW VISIBILITIES. THE SNOW WILL IMPACT THE MORNING COMMUTE
ESPECIALLY OVER EAST CENTRAL IOWA BUT SURFACE TEMPERATURES DURING
THE SNOW SHOULD BE IN THE UPPER 20S TO LOW 30S SUGGESTING MOST OF
THE SNOW WILL HAVE A DIFFICULT TIME ACCUMULATING ON ROADS. THE
OTHER AREA OF CONCERN WILL BE REDUCED VISIBILITIES. MODELS ARE
SHOWING A NARROW BAND OF FGEN WITH GOOD VERTICAL CONTINUITY AND ON
THE GRADIENT OF STEEPER MID LEVEL LAPSE RATES SUGGESTING A NARROW
BAND OF ENHANCED SNOWFALL RATES. IT ALSO APPEARS THAT THE THERMAL
PROFILES WILL SUPPORT DENDRITIC FLAKES DURING THE PERIOD OF ENHANCED
FORCING. IF THESE CONDITIONS VERIFY THEN VISIBILITIES DROPPING TO A
HALF MILE OR LESS WILL BE POSSIBLE AT TIMES MONDAY MORNING.
THE ACCUMULATING SNOW WILL END BY NOON IN THE NORTHEAST AS THE
BETTER FORCING MOVES EAST OF THE AREA. COLDER AIR AND STRONGER WINDS
MOVE IN DURING THE AFTERNOON CAUSING FALLING TEMPERATURES DURING THE
MID TO LATE AFTERNOON OVER THE NORTHWEST COUNTIES. THE BRISK
CONDITIONS WILL CONTINUE OVER NIGHT AS A SURFACE LOW MOVES THROUGH
THE WESTERN GREAT LAKES AND HIGH PRESSURE BUILDS SOUTHEAST INTO THE
MID/LOWER MISSOURI VALLEY. LOWS TUESDAY MORNING ARE EXPECTED TO
RANGE FROM AROUND 10 IN THE NORTH TO THE MID 20S SOUTH.
THE REST OF THE WEEK LOOKS COLD AND DRY WITH NORTHWEST FLOW
REMAINING OVER THE AREA BETWEEN A BROAD EASTERN US TROF AND RIDGING
OVER THE WESTERN U.S./EASTERN PACIFIC. A REINFORCING SHOT OF COLD
AIR IS PROGGED TO MOVE INTO THE REGION TUESDAY NIGHT RESULTING IN
SINGLE DIGIT LOWS NORTH AND AROUND 20 IN THE SOUTH WEDNESDAY MORNING
AND HIGHS WEDNESDAY IN THE LOW TO MID 20S NORTH TO MID 30S SOUTH.
AFTER WEDNESDAY TEMPERATURES WILL MODERATE A LITTLE WITH HIGHS
EXPECTED TO BE IN THE 30S TO LOW 40S AND LOWS IN THE 20S BY FRIDAY
AND SATURDAY. BUT THESE TEMPERATURES ARE STILL WELL BELOW NORMAL AS
WE APPROACH THE LAST WEEK OF MARCH.
DLF
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 335 AM CDT SUN MAR 17 2013
A STORM SYSTEM MOVE THROUGH MISSOURI WILL BRING PERSISTENT MVFR
CIGS TO THE REGION THROUGH SUNDAY EVENING. CIGS OF 1800 TO 3000 FT
WILL BE WIDESPREAD. THERE WILL BE A BREAK IN THE STRATUS THROUGH
MID TO LATE MORNING OVER PORTIONS OF EASTERN IOWA...BUT AS WINDS
ALOFT TURN TO THE EAST...THE STRATUS SHOULD FLOW BACK INTO ALL OF
EASTERN IOWA BY 16 T0 18Z SUNDAY. ANY OTHER BREAKS ARE IMPOSSIBLE
TO PREDICT WELL IN ADVANCE...AND WILL BE HANDLED WITH UPDATES AS
NECESSARY. OTHERWISE...NORTH WINDS WILL GRADUALLY TURN TO EAST
OVERNIGHT...AND SHOULD REMAIN AROUND 8 TO 12 KTS THROUGH THE
PERIOD. EAST WINDS ARE EXPECTED THROUGHOUT THE DAY SUNDAY AND
SUNDAY EVENING. DRY CONDITIONS ARE ANTICIPATED...WITH VISIBILITY 6
MILES OR BETTER. AFTER 06Z MONDAY...AREAS OF SNOW ARE LIKELY OVER
THE AREA AS ANOTHER STORM MOVES EAST. ERVIN
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...12
SHORT TERM...12
LONG TERM...DLF
AVIATION...ERVIN
AREA FORECAST DISCUSSION
NWS TOPEKA KS
333 AM CDT SUN MAR 17 2013
.DISCUSSION...
A MIX OF PRECIPITATION WAS OCCURRING ACROSS NORTH CENTRAL AND
NORTHEAST KANSAS NORTH OF INTERSTATE 70 AT 08Z. A MIX OF
RAIN...SLEET AND SNOW HAS BEEN OBSERVED. EXPECT THIS PRECIPITATION
TO MOVE OUT OF THE AREA LATER THIS MORNING. RUC AND SREF SUGGEST
SOME REDEVELOPMENT OF PRECIPITATION IN CENTRAL KANSAS LATER THIS
AFTERNOON AS SHORTWAVE MOVES OUT OF THE ROCKIES. COULD SEE SOME
LIGHT RAIN APPROACHING NORTH CENTRAL KANSAS BY EVENING. ACROSS THE
EAST CENTRAL THIS MORNING WILL SEE THE BEST CHANCES OF PRECIPITATION
SOUTH OF I-35 IN ZONE OF FRONTOGENESIS FROM SOUTH CENTRAL INTO EAST
CENTRAL KANSAS. THERMAL PROFILES WOULD SUGGEST THAT THIS
PRECIPITATION WILL BE ALL LIQUID. TEMPERATURES TODAY WILL ONLY RISE
INTO THE LOWER 40S FOR HIGHS.
SATELLITE WAS SHOWING AN UPPER LEVEL TROUGH MOVING ACROSS THE
PACIFIC NORTHWEST AND THIS SYSTEM WILL DEEPEN AND MOVE ACROSS THE
ROCKIES AND INTO THE NORTHERN AND CENTRAL PLAINS TONIGHT. FORCING
WILL BE MAXIMIZED TO THE NORTH OF THE NEBRASKA BORDER TONIGHT AS THE
PV ANOMALY MOVES ACROSS THE NORTHERN PLAINS...SO EXPECTING ONLY 30
TO 40 PERCENT CHANCES OF PRECIPITATION TONIGHT WITH LITTLE IN THE
WAY OF QPF. THERMAL PROFILES SUGGEST THAT PRECIPITATION WILL BE ALL
RAIN THIS EVENING THEN A MIX OF RAIN AND SNOW NORTH OF HIGHWAY 56
AND RAIN SOUTH. LOWS TONIGHT COOLING INTO THE LOWER TO MID 30S. THE
UPPER TROUGH AXIS SHOULD MOVE OUT OF EASTERN KANSAS TOWARD SUNRISE
MONDAY.
A DRY PERIOD IS EXPECTED FROM MONDAY THROUGH WEDNESDAY WITH A DRY
NORTHWEST FLOW. NEXT SHOT OF PRECIPITATION OCCURS THURSDAY THROUGH
FRIDAY AS WAA INCREASE ALONG WITH ISENTROPIC LIFT AHEAD OF AN
APPROACHING UPPER TROUGH. MODELS ALSO SUGGEST THAT PIECES OF ENERGY
WILL MOVE OUT OF THE ROCKIES ACROSS KANSAS DURING THIS PERIOD. THE
ECMWF IS COOLER WITH THE THERMAL PROFILES AND FORECAST SOUNDINGS
SUGGEST THAT IT WILL BE COLD ENOUGH FOR SNOW AND ALSO A RAIN AND
SNOW MIX. THIS STILL MAY CHANGE WITH LATER RUNS. THE SYSTEM MOVES
OUT LATE FRIDAY WITH DRY WEATHER FOR THE START OF THE WEEKEND.
53
&&
.AVIATION...
DRY AIR CONTINUES TO KEEP VFR CONDITIONS AT THE TERMINALS...BUT
ISENTROPIC LIFT WILL SATURATE THE LAYER AGAIN TO MVFR BY
07-08Z TIMEFRAME...THEN RA/SN MIX LIKELY EXPECTED BY 09Z. AS WAVE
MOVES PAST EXPECT THIS PRECIP TO END BY 14Z BUT MVFR CIGS SHOULD
REMAIN THROUGH 06Z/18. WILL KEEP NORTHEAST WINDS THROUGH THE FCST
PERIOD AT 10-15 KTS.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
536 AM EDT SUN MAR 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 526 AM EDT SUN MAR 17 2013
LATEST GFS ANALYSIS SHOWS HIGH LATITUDE POSITIVE HEIGHT ANOMALIES
OVER GREENLAND AND N OF ALASKA WITH A W-E ELONGATED POLAR VORTEX TO
THE S DOMINATING MUCH OF CANADA. CENTER OF VORTEX WAS OVER HUDSON
BAY. SHORTWAVE TROF EXTENDING FROM THE CENTER HAS SWEPT E OF THE
UPPER GREAT LAKES DURING THE NIGHT. IN THE WAKE OF THE WAVE...850MB
TEMP WAS -23C ON 00Z KINL RAOB...AND LATEST RUC ANALYSIS SHOWS 850MB
TEMPS AROUND -20C OVER LAKE SUPERIOR. DESPITE STRONG OVERWATER
INSTABILITY...LES HAS BEEN POORLY ORGANIZED (NO REAL BANDING) AND
GENERALLY LIGHT TO PERHAPS ONLY MDT INTENSITY AT TIMES DESPITE DGZ
DOMINATING CONVECTIVE LAYER AND DESPITE KMQT VAD WIND PROFILE
SHOWING CLOUD TOPS TO 6-7KFT MSL AND NEARLY UNIDIRECTIONAL FLOW THRU
CLOUD DEPTH. DRY ADIABATIC LAPSE RATES BELOW INVERSION PER UPSTREAM
00Z KINL/CWPL SOUNDINGS IS PROBABLY A CONTRIBUTOR TO THE POOR
ORGANIZATION AS IS INFLUX OF DRIER AIR. GIVEN THE LACK OF
ORGANIZATION AND WEAK INTENSITY OF LES...OPTED TO CANCEL LES ADVY
NEAR LAKE SUPERIOR OVER THE E.
SFC HIGH PRES OVER NRN MN WILL QUICKLY MOVE ACROSS THE FCST AREA
TODAY. IN FACT...CENTER SHOULD BE OF THE AREA BY LATE AFTN. AS A
RESULT...ONGOING DIMINISHING LES WILL END W TO E AS NW WINDS BECOME
LIGHT/VRBL THEN SOUTHERLY AFTER SFC HIGH PASSES. MAY SEE AN
ADDITIONAL INCH OF FLUFFY SNOW E OF MARQUETTE IN THE MORNING BEFORE
THE LES ENDS. OTHERWISE...SKIES SHOULD TURN MOSTLY SUNNY W-E AFTER
WIND SHIFT TO THE S FOLLOWING PASSAGE OF THE SFC HIGH PRES. THE DAY
WILL PROBABLY BEGIN MOSTLY SUNNY OVER THE SCNTRL WHERE DOWNSLOPING
IS ALREADY LEADING TO MOSTLY CLEAR SKIES. DESPITE INCREASING
SUNSHINE...HIGH TEMPS WILL ONLY REACH INTO THE 20S WITH 850MB TEMPS
RECOVERING TO -8C TO -12C IN THE AFTN.
DRY WEATHER WILL CONTINUE TONIGHT. HIGH AND THEN MID CLOUDS WILL BE
ON THE INCREASE AHEAD OF VIGOROUS SHORTWAVE THAT IS NOW MOVING
ACROSS THE PACIFIC NW INTO THE NRN ROCKIES. INCREASING CLOUDS AND
INCREASING SE WINDS WILL KEEP TEMPS FROM FALLING SIGNIFICANTLY. SOME
OF THE TRADITIONAL COLD SPOTS MAY DROP TO AROUND 10F...BUT MOST
AREAS SHOULD SEE MINS IN THE MID/UPPER TEENS WITH A SLIGHT RISING
TREND TO TEMPS LATE.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 526 AM EDT SUN MAR 17 2013
PRIMARY FOCUS HAS BEEN AND CONTINUES TO BE UPR TROUGH/LOW PRESSURE
SYSTEM MOVING ACROSS UPPER GREAT LAKES ON MONDAY. IN GENERAL MODELS
INDICATE ADVY SNOW EVENT FOR MUCH OF CWA...BUT AT LEAST AS OF THIS
MORNING DOES NOT APPEAR TO BE A BLOCKBUSTER MARCH STORM BY UPPER
LAKES STANDARDS. ONE REASON SYSTEM IS NOT AS STRONG AS IT COULD BE
IS GULF MOISTURE TRYING TO SURGE NORTHWARD IS INTERCEPTED BY SMALLER
AREA OF SFC-H85 LOW PRESSURE SLIDING FROM SOUTHERN PLAINS INTO OHIO
VALLEY. PWATS INTO THAT AREA ARE WELL OVR 200 PCT OF NORMAL WHILE
THEY STAY ONLY AROUND NORMAL INTO WISCONSIN AND UPR MICHIGAN. SECOND
REASON LARGER SCALE SYSTEM IMPACTING AREA ON MONDAY IS NOT AS STRONG
IS DUE TO LIMITED JET ENHANCEMENT/DEEPENING OF H5 LEVEL LOW AS IT
SLIDES ACROSS UPR LAKES REGION. LAST COUPLE RUNS OF GFS/GEM-NH HAVE
TRENDED A BIT DEEPER WITH SFC-H85 LOWS THOUGH AND THIS RESULTS IN A
WETTER TREND FM THE GFS...WITH 12HR QPF OF 0.25-0.30 INCH OVR MOST
OF WEST HALF OF CWA 18Z MONDAY THROUGH 06Z TUESDAY. LARGE SCALE
ENHANCEMENT FACTORS TO BOOST PRECIP ARE MINOR AS NAM/GFS INDICATE
BRIEF PERIOD OF MOISTURE ADVECTION 850-800MB WITH MINIMAL TEMP
ADVECTION IN THAT LAYER. ALSO THERE IS NO JET SUPPORT AND MINIMAL
FRONTOGENESIS SINCE TEMPERATURE GRADIENT SFC-H85 IS LACKING.
THUS...APPERS THAT MOISTURE ADVECTION AND INCREASING CYCLONIC FLOW
AROUND SFC-H85 LOWS WILL DRIVE THE SNOW. EXPECT MOST SNOW TO OCCUR
THROUGH 00Z TUESDAY OVR SW TIER AND 18-21Z MONDAY THROUGH 03Z
TUESDAY IN THE NORTH AND EAST CWA. CONSENSUS OF MODELS FAVOR THAT
TIMING AND THERE IS GOOD AGREEMENT FROM SREF MEMBERS AS WELL. ONE
MESOSCALE EFFECT THAT MAY RESULT IN MORE SNOW IS POSSIBLE LAKE
ENHANCEMENT WITH ESE BLYR WINDS ON THE KEWEENAW AS H85 TEMPS ARE AT
OR COLDER THAN -8C. SHOWED ENHANCED QPF/SNOW FOR KEWEENAW ON MONDAY
AFTN/EVENING TO ACCOUNT FOR THIS. SLR/S FOR THIS EVENT WILL NOT BE TOO
OFF FROM 16:1 CLIMATOLOGY MARK...IF ANYTHING MAY BE SLIGHTLY LOWER
BUT STILL ABOVE 10:1. OVERALL 3"/12HR SEEMS PROBABLE OVER MUCH OF THE
AREA WHICH IS ADVY CRITERIA. MAYBE MORE SNOW OVER FAR WEST AND ACROSS
KEWEENAW PENINUSLA. WPC WWD GRAPHICS INDICATE 4-6 INCHES FOR THOSE
AREAS...WHICH ACTUALLY LINES UP WELL WITH CURRENT FORECAST THINKING.
SINCE BULK OF SNOW OCCURS LATER IN THE 3RD PERIOD...WILL NOT ISSUE
ANY ADVISORIES FOR SYSTEM SNOW ON MONDAY YET.
LK EFFECT INCREASES ON MONDAY NIGHT INTO TUESDAY FOR AREAS FAVORED
BY WNW-NW FLOW. A MAJORITY OF SNOW FROM THE SYSTEM WILL LIKELY COME
DURING THAT TIME AND ADDITIONAL HEADLINES MAY BE NEEDED INTO
TUESDAY. NAM SOUNDINGS INDICATE DEPTH OF LK EFFECT CONVECTIVE LAYER
BUILDS THROUGHOUT THE NIGHT WITH EQL PEAKING OVER 10KFT BTWN 09Z-12Z
ON TUESDAY IN THE WESTERN CWA AND AROUND 15Z ON TUESDAY IN THE
NORTHEAST CWA. GFS /WHICH IS PREFERRED BY WPC WITH TIMING OF THE
SYSTEM DUE TO ITS CONSISTENCY/ SHOWS SIMILAR SETUP BUT IS SLIGHTLY
SLOWER WITH TIMING. SINCE SOUNDINGS INDICATE MAJORITY OF LK
CONVECTIVE LAYER WITHIN THE DGZ...SLR/S WILL PUSH WELL OVER 20:1.
STRONG WINDS OVER 25 KTS IN THE BLYR WILL CUT SLR/S DOWN SLIGHTLY
THOUGH. HIGH SLR/S WITH PERSISTENT CONVERGENCE AND MORE THAN AMPLE
OVER-WATER INSTABILITY WILL RESULT IN AT LEAST MODERATE LK EFFECT
SNOWS FOR FAVORED AREAS. HINT AT REINFORCING SHOT OF COLDER AIR
LATER TUESDAY NIGHT SO AFTER SLIGHT DIMINISHING TREND INTO TUESDAY
EVENING MAY SEE ANOTHER UPTICK IN LK EFFECT AS THE TROUGH AND COLDER
AIR ARRIVE.
STEADY STATE LK EFFECT SETUP CONTINUES INTO WEDNESDAY NIGHT AND
KEPT CATEGORICAL POPS GOING FOR NW FLOW AREAS. SEVERAL INCHES OF
FLUFFY LK EFFECT SNOW SHOULD ACCUMULATE WEDNESDAY AND WEDNESDAY
NIGHT. ACCUMS IN SOME AREAS LIKELY WILL EXCEED A FOOT IN THE 48 HOUR
TIME FRAME TUESDAY THROUGH WEDNESDAY. OTHER HAZARD WILL BE BLOWING
SNOW AND REDUCED VSBY OVER MUCH OF THE EASTERN CWA AS NW WINDS GUST
OVER 25 KTS THROUGH WEDNESDAY. OCCASIONAL WHITEOUTS SEEM LIKELY...
ESPECIALLY ALONG LK SUPERIOR TUESDAY AFTN THROUGH WEDNESDAY MORNING.
WILL CONTINUE TO MENTION THE PROLONGED PERIOD OF MODERATE-HEAVY LK
EFFECT SNOW AND CONSIDERABLE BLSN IN THE HAZARDOUS WEATHER OUTLOOK.
OUR BACKLOADED WINTER JUST WILL NOT LET GO. LK EFFECT GRADUALLY
DIMINISHES INTO THURSDAY AS LOW PRESSURE TROUGH OVER THE REGION
BEGINS TO RELAX. PROBABLY CAN NOT COUNT OUT LGT LK EFFECT OR FLURRIES
INTO AT LEAST FIRST PART OF NEXT WEEKEND THOUGH AS ECMWF/GFS SHOW
WEAK ONSHORE WINDS CONTINUING BTWN HIGH PRESSURE OVER SCNTRL CANADA
AND TROUGHING OVER EASTERN CANADA/NEW ENGLAND. AFTER TEMPS NEAR 30
DEGREES ON MONDAY AHEAD OF DEVELOPING LOW PRESSURE SYSTEM...DAYTIME
TEMPS FOR THE REST OF THE WEEK WILL BE BLO NORMAL. ONLY GRADUAL
WARMING INTO 30S FOR NEXT WEEKEND. &&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 140 AM EDT SUN MAR 17 2013
LAKE EFFECT SNOW SHOWERS WILL CONTINUE TO DIMINISH OVERNIGHT AS HIGH
HIGH PRES BUILDS INTO THE REGION WITH SUBSIDENCE AND LOW LEVEL
DIFFLUENT FLOW. HOWEVER...LAKE EFFECT CLOUDS AND FLURRIES SHOULD
STILL LINGER AT CMX INTO THE MORNING BEFORE CLOUDS SCATTER OUT.
OTHERWISE...EXPECT IMPROVEMENT TO VFR CONDITIONS AT SAW OVERNIGHT AND
CONTINUING VFR AT IWD. AS WINDS BECOME VARIABLE AND THEN SOUTHERLY
TODAY...DRY LOW LEVEL LEVEL AIR WILL PERSIST WITH ONLY SCT-BKN HIGH
CLOUDS PREVAILING INTO THE EVENING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 526 AM EDT SUN MAR 17 2013
WITH HIGH PRES QUICKLY MOVING ACROSS LAKE SUPERIOR TODAY...EXPECT A
PERIOD OF LIGHT WINDS UNDER 15KT. THE DIMINISHING WINDS/WAVES WILL
BRING AN END TO HVY FREEZING SPRAY EARLY THIS MORNING. AS THE HIGH
CONTINUES E...REACHING NEW ENGLAND MON...LOW PRES EMERGING OVER THE
WRN DAKOTAS THIS AFTN WILL TRACK E...REACHING THE UPPER GREAT LAKES
MON NIGHT. TIGHT PRES GRADIENT BTWN THE DEPARTING HIGH AND
APPROACHING LOW WILL BRING SE WINDS UP TO 30KT TONIGHT AND MON. SOME
GALE FORCE GUSTS TO 35KT WILL BE POSSIBLE LATE TONIGHT/MON OVER
PORTIONS OF NCNTRL AND ERN LAKE SUPERIOR. AFTER THE LOW EXITS TO THE
E...NORTHWEST GALES WILL DEVELOP FROM W TO E LATE MON NIGHT/TUE.
THE GALES WILL THEN CONTINUE INTO WED OVER THE E HALF OF THE LAKE.
WINDS WILL SLOWLY DIMINISH TO UNDER 25KT FROM W TO E WED NIGHT/THU.
THE COMBINATION OF COLD AIR/STRONG WINDS/HIGH WAVES WILL LEAD TO
PERIODS OF HVY FREEZING SPRAY TUE THRU WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 9 AM EDT THIS MORNING FOR
LSZ245-248>251-265>267.
HEAVY FREEZING SPRAY WARNING UNTIL 6 AM EDT /5 AM CDT/ EARLY
THIS MORNING FOR LSZ240>244-263-264.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...JLB
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
328 AM CDT SUN MAR 17 2013
.DISCUSSION...
THE CHANCE FOR RAIN AND SNOW TONIGHT THEN WINDS BEHIND COLD FRONT
MONDAY ARE THE PRIMARY FORECAST CONCERNS.
A COUPLE OF AREAS OF PRECIPITATION WERE IN OR NEAR OUR CWA THIS
MORNING. LIGHT SNOW MOVED FROM NORTH CENTRAL INTO NORTHEAST NEBRASKA
DURING THE LATE EVENING...DROPPING A DUSTING TO A HALF INCH OF SNOW
FOR SOME OF OUR NORTHERN AREAS. THIS SEEMED TO BE TIED TO 90-120KT
300MB JET STRETCHING FROM NORTHERN NEBRASKA INTO THE GREAT LAKES.
WITH THAT JET SHIFTING EAST THIS MORNING...THINK ANY LINGERING SNOW
SHOWERS WILL BE SHORT-LIVED AFTER SUNRISE. SHORT RANGE MODELS RAP
AND HRRR CONCUR. THE SECOND AREA OF PRECIPITATION WAS STAYING MOSTLY
SOUTH OF THE CWA ACROSS NORTHERN KANSAS...AND LOOKED TO BE CAUSED BY
MID LEVEL WARM ADVECTION AHEAD OF 700MB SHORTWAVE MIGRATING EAST
THROUGH KANSAS. A FEW RADAR RETURNS MOVED ACROSS THE SOUTHEAST
NEBRASKA BORDER...BUT TRENDS HAVE BEEN TO CONCENTRATE PRECIP JUST
SOUTH OF OUR AREA. SO ONLY SMALL CHANCES EARLY TODAY THERE...WITH
LIGHT SNOW THE MAIN PRECIP TYPE.
ATTENTION THEN TURNS TO STRONG MID LEVEL SHORTWAVE NOW DIVING
THROUGH WASHINGTON AND OREGON INTO IDAHO. THIS FEATURE WILL RACE
EAST AND STRENGTHEN TODAY...REACHING THE WESTERN DAKOTAS BY
00Z...WITH AXIS OF MID LEVEL TROUGH SWINGING THROUGH OUR AREA MONDAY
MORNING. STRONG SURFACE LOW WILL DEVELOP IN THE NORTHERN HIGH PLAINS
THROUGH THE DAY...THEN ROTATE THROUGH THE DAKOTAS OVERNIGHT WHILE
DRIVING A COLD FRONT THROUGH NEBRASKA AND WESTERN IOWA BY SUNRISE
MONDAY. SOUTHEAST TO SOUTH LOW LEVEL FLOW WILL DEVELOP IN OUR AREA
TODAY IN RESPONSE TO LOWERING PRESSURES TO OUR NORTHWEST...AND WILL
PUSH TEMPERATURES TOWARD 40 THIS AFTERNOON. MID LEVEL THETA-E
INCREASE IN DIFFLUENT FLOW REGIME AHEAD OF TROUGH WILL PROVIDE
SUFFICIENT MOISTURE/LIFT FOR PRECIPITATION AS EARLY AS THIS
AFTERNOON IN CENTRAL AND PERHAPS NORTHEAST NEBRASKA. BUT BETTER
CHANCES COME OVERNIGHT AHEAD OF SURFACE COLD FRONT UNDER CORE OF MID
LEVEL JET SEGMENT. HAVE KEPT PRECIPITATION CHANCES RELATIVELY
HIGH...WITH BEST CHANCES ACROSS THE NORTH NEARER BETTER COMBINATION
OF LIFT/MOISTURE.
PRECIPITATION TYPE CONTINUES TO BE AN ISSUE AS SURFACE LAYER REMAINS
ABOVE FREEZING UNTIL COLD FRONT ARRIVES. MODEL DEPICTIONS OF LAYER
TEMPERATURE PROFILES ARE NOT CONSISTENT WITH EACH OTHER...AND
TEMPERATURE TRENDS WITHIN THE SAME MODEL SPORADICALLY MOVE THERMAL
PROFILE FROM JUST ABOVE TO JUST BELOW FREEZING AND BACK AGAIN WITH
TIME. THIS IS LIKELY DUE TO DYNAMIC COOLING EFFECTS GIVEN VIGOROUS
BUT SMALL AREAS OF LIFT UNDER FAST FLOW. SO A VARIETY OF WEATHER
TYPES ARE POSSIBLE FROM TIME TO TIME OVERNIGHT...BUT WILL FOCUS THIS
FORECAST ON TIMING OF PREDOMINANT WEATHER TYPE CHANGING FROM MAINLY
RAIN TO MAINLY SNOW...AND LET POTENTIAL SNOW AMOUNTS FALL OUT OF
THAT THINKING.
THERMAL PROFILES WILL SUPPORT RAIN FROM LATE THIS AFTERNOON THROUGH
MID EVENING...WITH THICKNESS PROGS SUGGESTING A TRANSITION TOWARD
SNOW IN OUR NORTHWEST BY 03Z. THAT TREND WILL QUICKLY SWING EAST AND
SOUTHEAST THROUGH 06Z...WITH MAINLY SNOW EXPECTED IN OUR SOUTH AFTER
09Z. BETTER COOLING REGIME IS EXPECTED ACROSS OUR NORTH...SO HIGHER
POTENTIAL SNOW TOTALS THERE. HOWEVER...STRONG LIFT NEAR AND
NORTH/NORTHEAST OF THE OMAHA METRO AREA AROUND 06Z MAY END UP BEING
THE MAIN SNOW ZONE WITH THIS SYSTEM. AN ENSEMBLE APPROACH TO SNOW
AMOUNT FORECAST SUGGESTS 1 TO 2 INCHES WILL BE COMMON FROM NORTHEAST
NEBRASKA INTO WEST CENTRAL IOWA. THIS COMBINES STRAIGHT MODEL
OUTPUT...COBB CALCULATIONS OF SEVERAL MODELS...AND A GARCIA
MANIPULATION OF MIXING RATIOS TAKING INTO ACCOUNT 6 HOUR PERIOD OF
PRECIPITATION AND A TRANSITION FROM RAIN TO SNOW OCCURRING NEAR THE
MIDWAY POINT OF THE PRECIP.
FAST-MOVING SYSTEM SHOULD TAKE MOST PRECIPITATION EAST OF OUR WESTERN
IOWA COUNTIES BY 12Z MONDAY. STRONG WINDS WILL FOLLOW DURING THE DAY
AS UNIDIRECTIONAL NORTHWEST FLOW AND STRONG COLD ADVECTION POINT TO
EFFECTIVE TRANSFER OF MOMENTUM IN THE BOUNDARY LAYER. FORECAST
SOUNDINGS STILL SHOW THE POTENTIAL FOR 40MPH WIND GUSTS ON MONDAY.
AND AM NOT EXPECTING A LOT OF WARMING MONDAY GIVEN COLD ADVECTION
DESPITE CLEARING SKIES. HAVE HIGHS GENERALLY IN THE 30S NORTH TO
LOWER 40S SOUTH.
THE REST OF THE WEEK STILL LOOKS TO BE COOL. TUESDAY MAY BE THE
WARMEST...OR LEAST COOL...DAY OF THE WEEK WHERE A RELATIVELY MILD
START AND SUNSHINE ALLOW TEMPS TO REBOUND INTO 40S. OTHERWISE
NORTHWEST MID LEVEL FLOW AT MID WEEK WILL BE REPLACED BY WAVE/LOW
APPROACHING FOR THE END OF THE WEEK INTO THE WEEKEND. OFF-AND-ON
PRECIPITATION CHANCES WILL RESULT BEGINNING WEDNESDAY NIGHT...WITH
CLOUDS AND LITTLE IN THE WAY OF WARM/COLD ADVECTION SUGGESTING
TEMPERATURES WILL BE RANGE-BOUND IN THE 20S FOR LOWS AND 30S OR
LOWER 40S FOR HIGHS.
DERGAN
&&
.AVIATION...06Z TAFS FOR KOMA...KLNK...KOFK.
CEILINGS WILL BE THE MAIN CONCERN THROUGH THE PERIOD. LOW CLOUDS
HAD SCATTERED OUT AT THE TAF SITES THIS EVENING...BUT SHOULD MOVE
BACK IN AT LEAST TEMPORARILY OVERNIGHT AND THROUGH MID MORNING
SUNDAY. EXPECT INCREASING SOUTHEAST WINDS AND GENERALLY VFR
CONDITIONS FROM LATE MORNING THROUGH MID AFTERNOON. MVFR CEILINGS
SHOULD MOVE BACK IN WITH NEXT SYSTEM APPROACHING. DID MENTION
POTENTIAL FOR A RAIN/SNOW MIX FOR KOMA AND KOFK SUNDAY EVENING...
BUT NOT FOR KLNK AT THIS TIME. PCPN TYPE WILL NEED TO BE ADJUSTED
AS THE EVENT GETS CLOSER...SINCE PCPN COULD CHANGE TO ALL SNOW...
ESPECIALLY AT KOFK.
MILLER
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1123 PM MDT SAT MAR 16 2013
.UPDATE...
ISSUED AT 600 PM MDT SAT MAR 16 2013
VIGOROUS LIFT ASSOCIATED WITH A ZIPPERING TROUGH ALONG A QUASI-
STATIONARY FGEN ZONE...HAS BEEN SUPPORTING HEAVY SNOWFALL ALONG
NARROW BAND OVER WEST CENTRAL SD. LATEST GUIDANCE SUGGEST
CONCENTRATED LIFT WILL CONTINUE ACROSS MAINLY
PENNINGTON/JACKSON/AND INTO MELLETTE COUNTIES THROUGH MUCH OF THIS
EVENING...WITH VERY EFFICIENT SNOW PRODUCTION GIVEN LIFT FOCUSED
IN THE DGZ. LOSS OF INSOLATION WITH FALLING TEMPS HAS SUPPORTED
ACCUMS ON ROADWAYS WITH BLACK ICE LIKELY GIVEN EARLIER SNOW MELT.
LATEST QPF GUIDANCE AND CURRENT RADAR/SAT ANALYSIS SUGGEST THAT
2-5 INCHES OF ADDITIONAL ACCUMS WILL POSSIBLE THROUGH THIS
EVENING...ESP WHERE BANDING PERSISTS. IN ADDITION...SATELLITE
ANALYSIS COUPLED WITH THE 00Z RAP RAOB INDICATED A POTENTIALLY
UNSTABLE ENVIRONMENT WITH LIKELY CONVECTIVE ENHANCEMENT OWING TO
1-2 INCHES AN HOUR SNOWFALL RATES INSIDE THE BAND. HAVE ISSUED A
WINTER WEATHER ADV.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 226 PM MDT SAT MAR 16 2013
UPPER LEVEL ANALYSIS HAS ZONAL FLOW OVER THE NORTHERN PLAINS WITH
WEAK SHORTWAVE CROSSING SOUTHEASTERN MONTANA AND NORTHEASTERN
WYOMING AT THE MOMENT. REGIONAL RADARS SHOWING A LIGHT TO MODERATE
BAND OF SNOW FROM THE CENTRAL AND SOUTHERN BLACK HILLS EXTENDING
EAST ONTO THE PLAINS. SEVERAL INCHES OF SNOW HAS FALLEN IN AREAS
WHERE THE HEAVIEST BANDS HAVE SET UP. AT THE SURFACE...ARCTIC HIGH
HAS SETTLED INTO NORTH DAKOTA WITH COOLER AIR BACKING INTO WESTERN
SOUTH DAKOTA. BROAD AREA OF STRATUS IN PLACE ACROSS SOUTHWESTERN
SOUTH DAKOTA AS WARMER/MOISTER AIR OVERRUNS THE COOLER AIR AT THE
SURFACE.
LATE THIS AFTERNOON AND TONIGHT...BAND OF SNOW EXTENDING FROM THE
BLACK HILLS EASTWARD WILL CONTINUE TO PRODUCE LIGHT TO MODERATE
SNOW FOR THE REMAINDER OF THE AFTERNOON AND EARLY EVENING. ONE TO
TWO ADDITIONAL INCHES OF SNOW WILL BE POSSIBLE...WITH SOME LOCALLY
HIGHER AMOUNTS. LIGHT SNOW WILL FINALLY SHIFT EAST LATER TONIGHT
AS MAIN SHORTWAVE MOVES OUT AND WEAK TRANSIENT RIDGE BUILDS IN.
FOR SUNDAY...STRONG/FAST MOVING SHORTWAVE TROUGH WILL MOVE FROM
WESTERN MT/ID TO MN BY 12Z MONDAY. SURFACE LOW WILL DEVELOP ALONG
THE MT/WY BORDER...MOVING INTO WESTERN SD BY 00Z...AND THEN
NORTHEAST MN BY 12Z MONDAY. IT WILL DRAG A STRONG COLD FRONT
THROUGH THE CWA SUNDAY AFTERNOON/EVENING. AHEAD OF THE FRONT 30KT+
SOUTHERLY JET DEVELOPS WHICH WILL PARTIALLY MIX TO THE GROUND BY
MIDDAY RESULTING IN WINDY SPOTS ACROSS SOUTH CENTRAL SOUTH DAKOTA.
40KT+ 850MB WEST TO NORTHWEST WINDS DEVELOP BEHIND THE COLD FRONT
AS IT SHIFTS EAST. CURRENT HIGH WIND WATCH FOR MUCH OF WESTERN
SOUTH DAKOTA LOOKS GOOD. OTHER IMPACT OF COLD FRONT AND STRONG
WINDS WILL BE LOWER VISIBILITIES WITH SNOW SHOWERS AFTER FRONTAL
PASSAGE. WINDS LOOK TO REMAIN FAIRLY STRONG INTO SUNDAY NIGHT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 226 PM MDT SAT MAR 16 2013
DEEP NORTHWESTERLY FLOW ALOFT IS EXPECTED ACROSS THE REGION FOR THE
FIRST HALF OF THE WORK WEEK. WEAK DISTURBANCES IN THE FLOW WILL
BRING AT LEAST SLIGHT CHANCES FOR SNOW SHOWERS ACROSS FAR
NORTHEASTERN WY...THE BLACK HILLS...AND PORTIONS OF NORTHWESTERN SD
MONDAY THROUGH TUESDAY. OTHERWISE...MAINLY DRY WEATHER IS EXPECTED
THROUGH WEDNESDAY. TEMPERATURES WILL BE A BIT TRICKY EARLY IN THE
WEEK WITH FRONTAL BOUNDARY IN PLACE OVER THE AREA. AM GENERALLY
EXPECTING A WARMING TREND ACROSS WESTERN AREAS THROUGH MIDWEEK...
WITH BELOW AVERAGE TEMPERATURES TO THE EAST OF THE BLACK HILLS. THE
NEXT SERIES OF WEATHER SYSTEMS WILL MOVE INTO THE REGION LATER
WEDNESDAY NIGHT AND THURSDAY. THE STRONGEST OF THESE DISTURBANCES
LOOKS LIKE IT WILL MOVE THROUGH THURSDAY INTO THURSDAY NIGHT. WILL
KEEP POP CHANCES ON THE HIGH SIDE FOR THESE PERIODS. LONG RANGE
MODELS ARE HAVING A HARD TIME HANDLING THE PATTERN BEYOND
FRIDAY...BUT THEY ARE LEANING TOWARD DRIER NORTHWESTERLY FLOW INTO
NEXT WEEKEND...SO WILL GO WITH DRY FORECAST FOR SATURDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1102 PM MDT SAT MAR 16 2013
IFR TO LIFR CIGS AND VIS WILL CONTINUE ACROSS MOST OF THE FA INTO
SAT MORNING. SOUTHERLY WINDS WILL INCREASE AND MAY ALLOW THE
LIFTING OF SOME OF THE FOG TO STRATUS. AREAS OF FREEZING DRIZZLE
WILL BE POSSIBLE THROUGH MORNING...ESP IN AND AROUND THE BLACK
HILLS. SOUTHERLY WINDS WILL INCREASE THROUGH MORNING...BEING ESP
GUSTY OVER NE WY. STRONG LOW PRESSURE WILL DEVELOP AND PUSH EAST
THROUGH THE REGION SUNDAY...WITH VERY STRONG WESTERLY WINDS
DEVELOPING BEHIND THE SFC TROUGH/COLD FRONT. SUSTAINED WINDS OF 25
TO 40 MPH WITH GUSTS OVER 60 WILL BE POSSIBLE...ESP OVER THE
NORTHERN AND EASTERN FOOTHILLS OF THE BLACK HILLS. ANOTHER PERIOD
OF MVFR CIGS WILL BE POSSIBLE ACROSS THE NORTHERN FA...IN RAIN AND
SNOW BEHIND THE SFC COLD FRONT SUNDAY AFTERNOON AND EVENING.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...HIGH WIND WATCH FROM SUNDAY AFTERNOON THROUGH LATE SUNDAY NIGHT
FOR SDZ001-002-012-013-025-026-030-031-041>044-072>074.
WY...NONE.
&&
$$
UPDATE...JC
SHORT TERM...15
LONG TERM...26
AVIATION...JC
AREA FORECAST DISCUSSION...UPDATED
NWS SAN ANGELO TX
1129 PM CDT SAT MAR 16 2013
.UPDATE...
FORECAST HAS BEEN UPDATED MAINLY FOR OVERNIGHT WINDS AND LOW
TEMPERATURES...SEE DISCUSSION.
&&
.DISCUSSION...
THE COLD FRONT HAS MADE MORE SOUTHWARD PROGRESS DURING THE EVENING THAN
THE MODELS HAD INDICATED...AND HAS ENTERED THE NORTHERN CONCHO VALLEY.
RADAR LOOP INDICATES THAT THE FRONT IS CURRRENTLY SLOWING
DOWN...HOWEVER. THE LATEST RUC13 LOOKS TO HAVE THE BEST HANDLE ON THIS
FRONT...BRINGING IT SOUTH TO SAN ANGELO SHORTLY BEFORE 11Z. THE FRONT
SHOULD BE APPROACHING THE INTERSTATE 10 CORRIDOR AROUND MIDDAY SUNDAY.
BASED ON THESE CONSIDERATIONS...HAVE MADE SLIGHT DOWNWARD ADJUSTMENTS
TO OVERNIGHT LOWS ACROSS THE NORTHERN BIG COUNTRY...AND HAVE ADJUSTED
LOWS UP ACROSS OUR SOUTHERN COUNTIES. HAVE ALSO MADE ADJUSTMENTS TO
THE WIND...TEMPERATURE AND DEWPOINTS GRIDS TO MATCH WHAT HAS OCCURRED
DURING THE PAST FEW HOURS. UPDATED FORECAST PRODUCTS HAVE BEEN SENT.
&&
.PREV DISCUSSION... /ISSUED 544 PM CDT SAT MAR 16 2013/
DISCUSSION...
SEE AVIATION DISCUSSION BELOW...
AVIATION...
A COLD FRONT IS CURRENTLY OVER NORTH TEXAS AND WILL APPROACH KABI
AROUND 09Z...KSJT AROUND 12Z....AND THE SOUTHERN SITES BETWEEN 15
AND 16Z. WINDS WILL BECOME NORTH TO NORTHWEST AT 8 TO 12 KNOTS
BEHIND THE BOUNDARY...WITH SOME POST FRONTAL STRATUS REDUCING
CEILINGS TO AROUND 3K FEET...MAINLY AT KABI. IN
ADDITION...STRATUS DEVELOPMENT IS EXPECTED AROUND 12Z AT
KJCT...AHEAD OF THE FRONT...RESULTING IN MVFR CEILINGS. FOR NOW I
HAVE LEFT KBBD AND KSOA VFR...BUT I WILL CONTINUE TO MONITOR. VFR
CONDITIONS WILL RETURN TO ALL TAF SITES BY MID TO LATE MORNING
SUNDAY.
PREV DISCUSSION... /ISSUED 342 PM CDT SAT MAR 16 2013/
SHORT TERM...
A WEAK COLD FRONT WILL PUSH INTO THE BIG COUNTRY THIS EVENING AND
INTO THE CONCHO VALLEY TOWARD MORNING. THE SLIGHTLY FASTER NAM AND
RAP MODELS APPEAR TO PLACE THE FRONT BETTER THIS AFTERNOON. THE
FRONT MOVES ALONG THE I-20 CORRIDOR TOWARDS MIDNIGHT...AND THE
CONCHO VALLEY EARLY SUNDAY MORNING. WENT CLOSE TO GFS/NAM MOS FOR
HIGHS IN THE BIG COUNTRY SUNDAY...AS BOTH NAM AND GFS MODELS
INDICATE SOME POST FRONTAL STRATUS IN THE MORNING. GOING WARMER
HOWEVER SOUTH OF THE BIG COUNTRY...AS WINDS SHIFT WESTERLY IN THE
AFTERNOON...BRINGING A DOWNSLOPE COMPONENT ALONG WITH NEARLY FULL
SUN.
04
LONG TERM...
A VERY PROGRESSIVE MID/UPPER LEVEL PATTERN WILL UNLEASH A PARADE
OF SHORTWAVE TROUGHS ACROSS THE CENTRAL CONUS THROUGH THE
WEEKEND. WE WILL SEE ONE OF THESE SYSTEMS MOVE ACROSS THE SOUTHERN
PLAINS LATE SUNDAY NIGHT. THIS WILL REINFORCE TOMORROW/S COLD
FRONT WITH ANOTHER GLANCING BLOW OF COOLER AIR FOR MONDAY. TEMPS
ARE STILL EXPECTED TO REMAIN ABOVE NORMAL BUT MOST AREAS SHOULD BE
IN THE 70S FOR AFTERNOON HIGHS. NORTH TO NORTHWEST WINDS MAY BE
GUSTY EARLY BUT ARE FORECAST TO SUBSIDE AFTER 18Z AS THE SURFACE
HIGH BUILDS INTO THE REGION.
MODEL DIFFERENCES ARE ALREADY BECOMING AN ISSUE BY TUESDAY. WE
WILL SEE SOUTHERLY FLOW RETURN MONDAY NIGHT BUT ANOTHER
SHORTWAVE TROUGH WILL MOVE OUT OF THE FOUR CORNERS AND BRING
ANOTHER WEAK COLD FRONT INTO WEST CENTRAL TX. THE GFS IS THE ONLY
MODEL THAT TRIES TO DEVELOP ANY PRECIPITATION /TUESDAY EVENING/
DESPITE IT HAVING NO APPRECIABLE MOISTURE BELOW 10 KFT AGL. WITH
THE REMAINING MODELS SHOW NO SIGN OF THIS SO I HAVE IGNORED THESE
RAIN CHANCES. OTHERWISE...EXPECT HIGHS MAINLY IN THE MID/UPPER
70S. THE AFOREMENTIONED COLD FRONT WILL BRING COOLER TEMPS TO THE
AREA ON WEDNESDAY. I HAVE LOWERED MAX TEMPS INTO THE UPPER 60S TO
LOWER 70S AREAWIDE. EASTERLY WINDS...WEAK COLD ADVECTION AND
ABUNDANT MID/HIGH LEVEL CLOUD COVER SHOULD TEMPER WARMING.
ISENTROPIC ASCENT COULD BE STRONG ENOUGH TO PROVIDE SOME VERY
LIGHT SHOWERS BUT I WOULD LIKE TO SEE MORE CONTINUITY BEFORE
INTRODUCING THIS TO THE FORECAST.
SOUTH WINDS ARE EXPECTED TO RETURN BRIEFLY WEDNESDAY NIGHT WITH A
STRONG LOW LEVEL JET RESULTING IN RAPID POLEWARD MOISTURE
ADVECTION. I THINK DEWPOINTS WILL LIKELY REBOUND INTO THE LOWER
50S BY THURSDAY MORNING AND MAY INCREASE FURTHER AFTER SUNRISE.
THE QUESTION OF THE DAY IS WHETHER OR NOT THE DRYLINE/PACIFIC
FRONT WILL MOVE EAST OF THE CWA BY THURSDAY AFTERNOON OR WILL IT
FOLLOW THE LATEST MODEL TRENDS AND SLOW ENOUGH TO PROVIDE A FOCUS
FOR CONVECTION DURING THE AFTERNOON HOURS ACROSS THE EASTERN
ZONES. THE CONSENSUS /THROWING OUT THE MUCH MORE AGGRESSIVE DGEX/
WAS THAT WE MAY SEE THE BOUNDARY STALL JUST EAST OF AN ABILENE TO
SAN ANGELO LINE...WITH SUFFICIENT MOISTURE TO SUPPORT CONVECTION
IN THE WARM SECTOR. MODIFIED GFS POINT SOUNDINGS STILL SHOW SOME
SEMBLANCE OF AN ELEVATED MIXED LAYER CAPPING SURFACE BASED
CONVECTION BUT THE ECMWF REMOVES THIS CAP A BIT EARLIER AND SHOWS
LITTLE IN THE WAY OF CINH. I THOUGHT THE POTENTIAL WAS GREAT
ENOUGH TO AT LEAST INCLUDE MENTION IN THE FORECAST. SLIGHT CHANCE
POPS WERE ADDED TO AREAS EAST OF A HASKELL...TO BALLINGER...TO
SONORA LINE.
A STRONGER COLD FRONT IS PROGGED BY THE MEDIUM RANGE MODELS FOR
THURSDAY NIGHT INTO FRIDAY. H85 TEMPS ARE FORECAST TO DROP TO 0
TO -4C ACROSS THE BIG COUNTRY WITH LOW SINGLE DIGITS ACROSS THE
SOUTHERN ZONES. STRONG COLD ADVECTION IS EXPECTED TO RESULT IN
MUCH COOLER TEMPS FRIDAY AND SATURDAY. I HAVE KNOCKED HIGHS BACK
QUITE A BIT...SHOWING MAINLY 60S ON FRIDAY WITH 50S ON SATURDAY. I
ALSO LOWERED MIN TEMPS FRIDAY NIGHT INTO THE 30S IN THE DRY POST
FRONTAL AIR. THE ECMWF SUGGESTS THAT HIGHS WOULD REMAIN IN THE 40S
BUT THE GFS AND ENSEMBLES ARE A BIT WARMER.
JOHNSON
FIRE WEATHER...
ELEVATED FIRE WEATHER CONDITIONS WILL CONTINUE THIS AFTERNOON
AHEAD OF A COLD FRONT IN THE SOUTH PLAINS...SOUTH OF A LUBBOCK
TO CHILDRESS LINE. THE COLD FRONT WILL GRADUALLY MOVE SOUTHWARD
INTO THE BIG COUNTRY THIS EVENING... PUSHING SOUTH THE I-20
CORRIDOR AROUND MIDNIGHT...THEN INTO THE CONCHO VALLEY VALLEY
TOWARDS MORNING. THE COLD FRONT WILL BE SHORT LIVED HOWEVER...
WITH WINDS RETURNING TO THE WEST AND NORTHWEST SUNDAY AFTERNOON.
WINDS SPEEDS ON SUNDAY WILL BE LOWER SUNDAY...KEEPING FIRE WEATHER
CONDITIONS FROM BECOMING CRITICAL.
04
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 48 69 51 72 43 / 0 0 5 0 0
SAN ANGELO 52 82 49 78 44 / 0 0 0 0 0
JUNCTION 57 86 47 84 42 / 0 0 0 0 0
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1035 PM PDT Sat Mar 16 2013
.SYNOPSIS...
Breezy to windy conditions and colder temperatures will arrive
tonight as a cold front sweeps through the Inland Northwest. The
mountains will receive several inches of snow tonight into Sunday.
Breezy conditions will persist into Monday and the mountains will
continue to receive rain and snow showers. A break in the active
weather regime is expected on Tuesday before another strong storm
system brings wet and windy weather for Wednesday.
&&
.DISCUSSION...
Valley rain and mountain snow showers continue across the Inland
Northwest tonight. There were a few lightning strikes across the
upper Columbia Basin and the northeast zones as the cold front
moved through. There were a couple reports of small hail and gusty
winds with the thunderstorms. The convective showers will be
limited to extreme northeast WA and the northern panhandle of
Idaho through about 10 pm. There is still a slight chance of a
rumble or two of thunder with these showers but this will be very
localized and will be handled with NOWcasts. The focus for post
frontal snow showers will be on the Cascade Crest and the Puget
Sound convergence zone along with the north Idaho mts and NE
Blues. The HRRR has a pretty good handle on the precip so far,
including the Puget Sound Convergence Zone and the area of showers
headed for the NE Blue Mts. The afternoon forecast package was
leaning toward this model and remains in good shape. No big
changes for the evening update. /Kelch
&&
.AVIATION...
06Z TAFS: Scattered valley rain showers will transition to
snow showers for the Idaho panhandle overnight behind the cold
front. Windy conditions will continue overnight. Gusts of 30kts
or more will be possible at Pullman through the night with gusts
of 22kt to 27kt common at KGEG, KCOE, KMWH and KEAT. Instability
rain and snow showers will be possible again Sunday afternoon.
Gusty winds will continue through 02Z Monday then diminish. /EK
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 32 45 28 47 29 49 / 70 30 10 20 10 10
Coeur d`Alene 32 44 27 46 28 48 / 90 40 20 40 30 10
Pullman 30 43 28 46 30 50 / 70 30 20 20 10 20
Lewiston 36 50 33 53 34 57 / 40 30 10 10 10 10
Colville 33 48 29 51 28 55 / 50 30 10 20 10 10
Sandpoint 31 42 29 41 28 45 / 90 50 20 40 40 10
Kellogg 28 39 27 39 27 48 / 100 80 50 50 50 10
Moses Lake 35 52 32 56 31 56 / 20 10 0 0 10 30
Wenatchee 34 51 33 53 33 53 / 20 0 10 10 10 40
Omak 32 50 28 53 27 55 / 10 10 10 10 10 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
1011 AM CDT SUN MAR 17 2013
.DISCUSSION...
1010 AM CDT
JUST A FEW CHANGES MADE TO GOING FORECAST FOR TODAY...SIMPLY JUST
TO TOUCH UP HOURLY FORECAST TRENDS.
A STRONG CANADIAN HIGH PRESSURE CENTERED OVER THE NORTHERN LAKES
/RESPONSIBLE FOR -20F TO -30F LOWS OVER NORTHERN MN THIS MORNING/
IS HELPING TO DRIVE AN ENE WIND ACROSS THE AREA THAT WILL SHIFT
MORE DUE EAST THIS AFTERNOON. THE FLOW OFF THE LAKE HAS USHERED IN
AN UNSTABLE BOUNDARY LAYER WITH 850MB DELTA T VALUES AROUND -10C
TO -12C. WHILE SHALLOW...THIS STILL IS SUPPORTIVE OF CLOUDS AND
THE VISIBLE SATELLITE TREND INDICATES AN AXIS THAT HAS SWUNG WEST
FROM MID-LAKE NEAR DAYBREAK. THIS WILL CONTINUE TO SHIFT INLAND AND
LIKELY REACH ALL THE WAY TO ROCKFORD PER DISTANCE SPEED TRACKING
ALONG WITH RH SOLUTIONS FROM LOCAL ARW GUIDANCE. THICK HIGH
CLOUDS WILL CONTINUE TO STREAM ACROSS THE SOUTHEAST ALONG THE MID-
LEVEL BAROCLINIC ZONE...AND HAVE TAKEN MAX TEMPS DOWN ONE TO TWO
DEGREES TOWARD GIBSON CITY AND FOWLER.
EARLY LOOK AT TONIGHT INTO MONDAY INDICATES NO MAJOR IMMINENT
CHANGES TO THE FORECAST. THE TWO PRIMARY SHORT WAVES MENTIONED IN
THE PREV DISCUSSION MATCH UP WELL WITH THE NAM ANALYSIS AND
MORNING UPPER AIR CHARTS. LOOKING AT FORECAST SOUNDINGS FROM THE
NEW NAM AS WELL AS PREVIOUS GUIDANCE...PRECIP TONIGHT STILL
PRESENTS CONCERNS THAT COULD BE FREEZING WHERE IT IS
OCCURRING...WITH AROUND HALF OF THE PRECIP-PRODUCING 17.03 SREF
MEMBERS YIELDING FREEZING PRECIP AS FAR NORTH AS AT LEAST ORD
EARLY MONDAY MORNING. WILL LIKELY HAVE TO ADD A HUNDREDTH OR SO OF
ICE ACCUMULATION IN A PORTION OF THE SOUTHEAST HALF OR TWO-THIRDS OF
THE CWA OR SO...BUT WHERE PRECISELY STILL NEEDS TO BE FURTHER
ANALYZED AND REFINED. THE FAR SOUTHEAST WOULD RUN THE RISK OF
SEEING A LITTLE MORE ACCUMULATION DUE TO GETTING INTO THE BETTER
MOISTURE TRANSPORT AND ISENTROPIC ASCENT WITH TONIGHTS SOUTHERN
STREAM WAVE...ALTHOUGH THEIR SURFACE TEMPS MAY SUPPORT JUST LIQUID
RAIN. OTHERWISE...THE LIKELY SNOW AS THE PRIMARY PRECIP TYPE
ACROSS THE NORTH MONDAY MORNING AND EARLY AFTERNOON LOOKS GOOD.
MAY HAVE TO RE-INTRODUCE SOME LIGHT SNOW/FLURRY CHANCES ACROSS FAR
NORTHERN IL MONDAY NIGHT WITH THE UPPER LEVEL LOW PIVOTING ACROSS
WI...BUT DOES NOT LOOK LIKE MUCH FOR ACCUM IN THAT PERIOD WITH THE
BIGGER STORY BEING FALLING TEMPS AND WIND CHILLS.
MTF
&&
.PREV DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* LAKE EFFECT MVFR/VFR CIGS CONTINUING THROUGH MID AFTERNOON.
* NORTH TO NORTHEAST WINDS BECOMING MORE EASTERLY BY LATE
MORNING...AND THEN EAST TO SOUTHEAST THIS EVENING.
* CHANCES OF MIXED PRECIPITATION INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
PAW
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE CONTINUES TO WORK EASTWARD ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY AND LAKE SUPERIOR. AS A RESULT WINDS HAVE
TURNED NORTH-NORTHEAST ACROSS THE TERMINALS AND WILL SHIFT TO
EAST-NORTHEAST INTO EARLY AFTERNOON. MVFR CIGS HAVE CLEARED ALL
BUT GYY BUT WITH COLD AIR IN PLACE AND WINDS BEING DIRECTED DOWN
LAKE MICHIGAN MVFR LAKE EFFECT CLOUDS ARE EXPECTED TO WORK IN FROM
THE NORTHEAST THROUGH THE MORNING. SURFACE OBS SHOW CONVERGENCE
OVER THE LAKE WITH SATELLITE SHOWING ABUNDANT CLOUD COVER ACROSS
THE NORTHERN PART OF THE LAKE WITH CIRRUS SHROUDING THE VIEW OVER
THE SOUTHERN PART. RADAR MOSAIC DOES SHOW A PATCH OF VERY WEAK
REFLECTIVITY TO THE EAST OF MKE DRIFTING SOUTH-SOUTHWEST WHICH IS
LIKELY CLOUD COVER. SO WITH THIS IN MIND EXPECT THAT GYY WILL
CONTINUE AT MVFR THROUGH THE MORNING AND POSSIBLY EARLY AFTERNOON.
ORD/MDW/DPA SHOULD SEE MVFR CIGS ARRIVE OVER THE NEXT FEW HOURS AS
LOW LEVEL FLOW TURNS MORE NORTHEASTERLY. SOME FLURRIES ARE ALSO
POSSIBLE. THE FLOW WILL THEN TURN MORE EASTERLY ABOVE THE SURFACE
THIS AFTERNOON WHICH WILL SHORTEN THE FETCH DOWN THE LAKE WHILE
TEMPERATURES ALOFT WARM RESULTING IN UNFAVORABLE LAKE EFFECT
PARAMETERS...WHICH WILL ALLOW CLOUDS TO SCATTER. RFD MAY SEE A
PERIOD OF BKN MVFR CIGS TOO BUT HAVE LEFT THEM SCATTERED FOR NOW
WITH THE EXPECTATION THAT CLOUDS WILL SCATTER AS WINDS TURN
EASTERLY ENOUGH TO PUSH THEM AS FAR INLAND AS RFD. TIMING OF
SCATTERING WILL BE TRICKY SO ADJUSTMENTS MAY BE NEEDED.
FOCUS THEN TURNS TO LOW PRESSURE THAT WILL MOVE FROM THE LEE OF
THE NORTHERN ROCKIES TO LAKE SUPERIOR THROUGH MONDAY NIGHT. A PUSH
OF WARM/MOIST AIR WILL LEAD TO PRECIPITATION DEVELOPMENT EARLY
MONDAY MORNING WHICH WILL WORK NORTH AND EAST ACROSS THE
TERMINALS. FORECAST SOUNDINGS SHOW THAT MIXED PRECIPITATION IS
LIKELY WITH A GOOD CHANCE FOR A PERIOD OF FREEZING RAIN ACROSS THE
TERMINALS...BUT SNOW AND SLEET MAY MIX IN AT TIMES. MAY NEED TO
MOVE START TIME UP SLIGHTLY BUT 10Z LOOKS TO BE THE EARLIEST IN
THE CHICAGO AREA AND 09Z OR SO OUT TOWARDS RFD. PRECIPITATION
INTENSITY LOOKS LIGHT BUT SOME MINOR GLAZING OR SLUSHY
ACCUMULATION IS POSSIBLE DURING THE MORNING BEFORE TEMPERATURES
WARM WELL ABOVE FREEZING. CIGS WILL ALSO QUICKLY DROP WITH LOW END
MVFR LIKELY AND IFR POSSIBLE MONDAY MORNING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE IN DETAILS OF MVFR/VFR CEILINGS.
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
324 AM CDT
HIGH PRESSURE IS MOVING SOUTHEASTWARD TOWARD THE WESTERN GREAT LAKES
THIS MORNING WHILE A WEAK SURFACE LOW MOVES ACROSS EASTERN ONTARIO.
A TIGHT PRESSURE GRADIENT IS IN PLACE BETWEEN THESE TWO SYSTEMS WITH
STRONG NORTH-NORTHWEST WINDS BLOWING ACROSS MUCH OF THE CENTRAL AND
NORTHERN SECTIONS OF LAKE MICHIGAN. WINDS WILL DIMINISH THROUGH THE
MORNING ACROSS MOST OF THE LAKE AS THE HIGH MOVES OVERHEAD BUT THERE
WILL BE ENOUGH OF A PRESSURE GRADIENT IN PLACE TO THE SOUTH OF THE
HIGH OR ACROSS SOUTHERN LAKE MICHIGAN TO KEEP SLIGHTLY HIGHER WIND
SPEEDS GOING. WIND DIRECTION WILL SHIFT FROM NORTH-NORTHWEST TO EAST
THEN SOUTHEAST INTO THIS EVENING. SPEEDS WILL THEN INCREASE ACROSS
THE LAKE THIS EVENING AS THE HIGH DEPARTS TO THE EAST AND SURFACE
LOW PRESSURE MOVES EASTWARD ACROSS THE DAKOTAS AND ACROSS LAKE
SUPERIOR AND THE U.P. OF MICHIGAN BY MONDAY NIGHT. WILL GO AHEAD AND
EXTEND THE SMALL CRAFT FOR THE INDIANA NEARSHORE WATERS THROUGH LATE
AFTERNOON TODAY WITH WAVES EXPECTED TO STAY UP WITH THE NORTH TO
NORTHEAST WINDS. WILL ALSO ISSUE A SMALL CRAFT FOR THE ILLINOIS
NEARSHORE WATERS AS THE LONG FETCH OF NORTH THEN NORTHEAST WINDS
WILL BUILD WAVES THIS MORNING. WAVES WILL SUBSIDE LATER IN THE
AFTERNOON BUT WINDS WILL PICK UP TO SMALL CRAFT ADVISORY THRESHOLDS
DURING THE MID OR LATE EVENING WITH WAVES AGAIN BUILDING. WITH THIS
IN MIND WILL RUN THE SMALL CRAFT OUT THROUGH MONDAY MORNING THOUGH
THERE COULD BE A SHORT PERIOD WHERE WAVES FALL BELOW CRITERIA LATE
TODAY AND BEFORE WINDS COME UP ABOVE CRITERIA THIS EVENING.
A FURTHER SHIFT TO SOUTHWEST THEN WEST WINDS WILL OCCUR MONDAY
EVENING. COLDER AIR WILL SPREAD IN INTO TUESDAY AS THE LOW PASSES
AND THE PRESSURE GRADIENT WILL FURTHER STRENGTHEN LEADING TO A
PERIOD OF WEST TO NORTHWEST GALES...LIKELY IN THE 35-40 KT RANGE
STARTING MONDAY EVENING. RIGHT NOW MAINLY THE CENTRAL AND SOUTHERN
PORTIONS OF THE LAKE WILL SEE GALES WHILE THE FAR NORTH REMAINS
UNCERTAIN WITH THE EXPECTED TRACK OF THE LOW SHIFTING SLIGHTLY NORTH
AND SOUTH WITH RECENT FORECAST GUIDANCE. A FURTHER NORTH SOLUTION
WOULD RESULT IN A BETTER CHANCE OF THE NORTHERN THIRD SEEING GALES
AS WELL. SPEEDS WILL EASE LATER TUESDAY AFTERNOON BUT BE SLOW TO
REALLY QUIET DOWN THANKS TO THE LOW SLOWING AS IT PULLS OFF TO THE
EAST AND ANOTHER AREA OF HIGH PRESSURE NOSING INTO THE CENTRAL AND
NORTHERN PLAINS. THE FLOW THEN WEAKENS INTO FRIDAY WITH MAINLY A
NORTH TO NORTHEAST WIND EXPECTED THROUGH NEXT WEEKEND.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
910 AM CDT SUN MAR 17 2013
.DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* LAKE EFFECT MVFR/VFR CIGS CONTINUING THROUGH MID AFTERNOON.
* NORTH TO NORTHEAST WINDS BECOMING MORE EASTERLY BY LATE
MORNING...AND THEN EAST TO SOUTHEAST THIS EVENING.
* CHANCES OF MIXED PRECIPITATION INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
PAW
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE CONTINUES TO WORK EASTWARD ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY AND LAKE SUPERIOR. AS A RESULT WINDS HAVE
TURNED NORTH-NORTHEAST ACROSS THE TERMINALS AND WILL SHIFT TO
EAST-NORTHEAST INTO EARLY AFTERNOON. MVFR CIGS HAVE CLEARED ALL
BUT GYY BUT WITH COLD AIR IN PLACE AND WINDS BEING DIRECTED DOWN
LAKE MICHIGAN MVFR LAKE EFFECT CLOUDS ARE EXPECTED TO WORK IN FROM
THE NORTHEAST THROUGH THE MORNING. SURFACE OBS SHOW CONVERGENCE
OVER THE LAKE WITH SATELLITE SHOWING ABUNDANT CLOUD COVER ACROSS
THE NORTHERN PART OF THE LAKE WITH CIRRUS SHROUDING THE VIEW OVER
THE SOUTHERN PART. RADAR MOSAIC DOES SHOW A PATCH OF VERY WEAK
REFLECTIVITY TO THE EAST OF MKE DRIFTING SOUTH-SOUTHWEST WHICH IS
LIKELY CLOUD COVER. SO WITH THIS IN MIND EXPECT THAT GYY WILL
CONTINUE AT MVFR THROUGH THE MORNING AND POSSIBLY EARLY AFTERNOON.
ORD/MDW/DPA SHOULD SEE MVFR CIGS ARRIVE OVER THE NEXT FEW HOURS AS
LOW LEVEL FLOW TURNS MORE NORTHEASTERLY. SOME FLURRIES ARE ALSO
POSSIBLE. THE FLOW WILL THEN TURN MORE EASTERLY ABOVE THE SURFACE
THIS AFTERNOON WHICH WILL SHORTEN THE FETCH DOWN THE LAKE WHILE
TEMPERATURES ALOFT WARM RESULTING IN UNFAVORABLE LAKE EFFECT
PARAMETERS...WHICH WILL ALLOW CLOUDS TO SCATTER. RFD MAY SEE A
PERIOD OF BKN MVFR CIGS TOO BUT HAVE LEFT THEM SCATTERED FOR NOW
WITH THE EXPECTATION THAT CLOUDS WILL SCATTER AS WINDS TURN
EASTERLY ENOUGH TO PUSH THEM AS FAR INLAND AS RFD. TIMING OF
SCATTERING WILL BE TRICKY SO ADJUSTMENTS MAY BE NEEDED.
FOCUS THEN TURNS TO LOW PRESSURE THAT WILL MOVE FROM THE LEE OF
THE NORTHERN ROCKIES TO LAKE SUPERIOR THROUGH MONDAY NIGHT. A PUSH
OF WARM/MOIST AIR WILL LEAD TO PRECIPITATION DEVELOPMENT EARLY
MONDAY MORNING WHICH WILL WORK NORTH AND EAST ACROSS THE
TERMINALS. FORECAST SOUNDINGS SHOW THAT MIXED PRECIPITATION IS
LIKELY WITH A GOOD CHANCE FOR A PERIOD OF FREEZING RAIN ACROSS THE
TERMINALS...BUT SNOW AND SLEET MAY MIX IN AT TIMES. MAY NEED TO
MOVE START TIME UP SLIGHTLY BUT 10Z LOOKS TO BE THE EARLIEST IN
THE CHICAGO AREA AND 09Z OR SO OUT TOWARDS RFD. PRECIPITATION
INTENSITY LOOKS LIGHT BUT SOME MINOR GLAZING OR SLUSHY
ACCUMULATION IS POSSIBLE DURING THE MORNING BEFORE TEMPERATURES
WARM WELL ABOVE FREEZING. CIGS WILL ALSO QUICKLY DROP WITH LOW END
MVFR LIKELY AND IFR POSSIBLE MONDAY MORNING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE IN DETAILS OF MVFR/VFR CEILINGS.
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
324 AM CDT
HIGH PRESSURE IS MOVING SOUTHEASTWARD TOWARD THE WESTERN GREAT LAKES
THIS MORNING WHILE A WEAK SURFACE LOW MOVES ACROSS EASTERN ONTARIO.
A TIGHT PRESSURE GRADIENT IS IN PLACE BETWEEN THESE TWO SYSTEMS WITH
STRONG NORTH-NORTHWEST WINDS BLOWING ACROSS MUCH OF THE CENTRAL AND
NORTHERN SECTIONS OF LAKE MICHIGAN. WINDS WILL DIMINISH THROUGH THE
MORNING ACROSS MOST OF THE LAKE AS THE HIGH MOVES OVERHEAD BUT THERE
WILL BE ENOUGH OF A PRESSURE GRADIENT IN PLACE TO THE SOUTH OF THE
HIGH OR ACROSS SOUTHERN LAKE MICHIGAN TO KEEP SLIGHTLY HIGHER WIND
SPEEDS GOING. WIND DIRECTION WILL SHIFT FROM NORTH-NORTHWEST TO EAST
THEN SOUTHEAST INTO THIS EVENING. SPEEDS WILL THEN INCREASE ACROSS
THE LAKE THIS EVENING AS THE HIGH DEPARTS TO THE EAST AND SURFACE
LOW PRESSURE MOVES EASTWARD ACROSS THE DAKOTAS AND ACROSS LAKE
SUPERIOR AND THE U.P. OF MICHIGAN BY MONDAY NIGHT. WILL GO AHEAD AND
EXTEND THE SMALL CRAFT FOR THE INDIANA NEARSHORE WATERS THROUGH LATE
AFTERNOON TODAY WITH WAVES EXPECTED TO STAY UP WITH THE NORTH TO
NORTHEAST WINDS. WILL ALSO ISSUE A SMALL CRAFT FOR THE ILLINOIS
NEARSHORE WATERS AS THE LONG FETCH OF NORTH THEN NORTHEAST WINDS
WILL BUILD WAVES THIS MORNING. WAVES WILL SUBSIDE LATER IN THE
AFTERNOON BUT WINDS WILL PICK UP TO SMALL CRAFT ADVISORY THRESHOLDS
DURING THE MID OR LATE EVENING WITH WAVES AGAIN BUILDING. WITH THIS
IN MIND WILL RUN THE SMALL CRAFT OUT THROUGH MONDAY MORNING THOUGH
THERE COULD BE A SHORT PERIOD WHERE WAVES FALL BELOW CRITERIA LATE
TODAY AND BEFORE WINDS COME UP ABOVE CRITERIA THIS EVENING.
A FURTHER SHIFT TO SOUTHWEST THEN WEST WINDS WILL OCCUR MONDAY
EVENING. COLDER AIR WILL SPREAD IN INTO TUESDAY AS THE LOW PASSES
AND THE PRESSURE GRADIENT WILL FURTHER STRENGTHEN LEADING TO A
PERIOD OF WEST TO NORTHWEST GALES...LIKELY IN THE 35-40 KT RANGE
STARTING MONDAY EVENING. RIGHT NOW MAINLY THE CENTRAL AND SOUTHERN
PORTIONS OF THE LAKE WILL SEE GALES WHILE THE FAR NORTH REMAINS
UNCERTAIN WITH THE EXPECTED TRACK OF THE LOW SHIFTING SLIGHTLY NORTH
AND SOUTH WITH RECENT FORECAST GUIDANCE. A FURTHER NORTH SOLUTION
WOULD RESULT IN A BETTER CHANCE OF THE NORTHERN THIRD SEEING GALES
AS WELL. SPEEDS WILL EASE LATER TUESDAY AFTERNOON BUT BE SLOW TO
REALLY QUIET DOWN THANKS TO THE LOW SLOWING AS IT PULLS OFF TO THE
EAST AND ANOTHER AREA OF HIGH PRESSURE NOSING INTO THE CENTRAL AND
NORTHERN PLAINS. THE FLOW THEN WEAKENS INTO FRIDAY WITH MAINLY A
NORTH TO NORTHEAST WIND EXPECTED THROUGH NEXT WEEKEND.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
650 AM CDT SUN MAR 17 2013
.DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* LAKE EFFECT MVFR CIGS LIKELY RETURNING MID/LATE MORNING THROUGH
EARLY/MID AFTERNOON.
* NORTH-NORTHEAST WINDS TURNING EAST-NORTHEAST INTO THE
AFTERNOON...THEN EAST-SOUTHEAST THIS EVENING.
* MIXED PRECIPITATION CHANCES INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
MDB
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE CONTINUES TO WORK EASTWARD ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY AND LAKE SUPERIOR. AS A RESULT WINDS HAVE
TURNED NORTH-NORTHEAST ACROSS THE TERMINALS AND WILL SHIFT TO
EAST-NORTHEAST INTO EARLY AFTERNOON. MVFR CIGS HAVE CLEARED ALL
BUT GYY BUT WITH COLD AIR IN PLACE AND WINDS BEING DIRECTED DOWN
LAKE MICHIGAN MVFR LAKE EFFECT CLOUDS ARE EXPECTED TO WORK IN FROM
THE NORTHEAST THROUGH THE MORNING. SURFACE OBS SHOW CONVERGENCE
OVER THE LAKE WITH SATELLITE SHOWING ABUNDANT CLOUD COVER ACROSS
THE NORTHERN PART OF THE LAKE WITH CIRRUS SHROUDING THE VIEW OVER
THE SOUTHERN PART. RADAR MOSAIC DOES SHOW A PATCH OF VERY WEAK
REFLECTIVITY TO THE EAST OF MKE DRIFTING SOUTH-SOUTHWEST WHICH IS
LIKELY CLOUD COVER. SO WITH THIS IN MIND EXPECT THAT GYY WILL
CONTINUE AT MVFR THROUGH THE MORNING AND POSSIBLY EARLY AFTERNOON.
ORD/MDW/DPA SHOULD SEE MVFR CIGS ARRIVE OVER THE NEXT FEW HOURS AS
LOW LEVEL FLOW TURNS MORE NORTHEASTERLY. SOME FLURRIES ARE ALSO
POSSIBLE. THE FLOW WILL THEN TURN MORE EASTERLY ABOVE THE SURFACE
THIS AFTERNOON WHICH WILL SHORTEN THE FETCH DOWN THE LAKE WHILE
TEMPERATURES ALOFT WARM RESULTING IN UNFAVORABLE LAKE EFFECT
PARAMETERS...WHICH WILL ALLOW CLOUDS TO SCATTER. RFD MAY SEE A
PERIOD OF BKN MVFR CIGS TOO BUT HAVE LEFT THEM SCATTERED FOR NOW
WITH THE EXPECTATION THAT CLOUDS WILL SCATTER AS WINDS TURN
EASTERLY ENOUGH TO PUSH THEM AS FAR INLAND AS RFD. TIMING OF
SCATTERING WILL BE TRICKY SO ADJUSTMENTS MAY BE NEEDED.
FOCUS THEN TURNS TO LOW PRESSURE THAT WILL MOVE FROM THE LEE OF
THE NORTHERN ROCKIES TO LAKE SUPERIOR THROUGH MONDAY NIGHT. A PUSH
OF WARM/MOIST AIR WILL LEAD TO PRECIPITATION DEVELOPMENT EARLY
MONDAY MORNING WHICH WILL WORK NORTH AND EAST ACROSS THE
TERMINALS. FORECAST SOUNDINGS SHOW THAT MIXED PRECIPITATION IS
LIKELY WITH A GOOD CHANCE FOR A PERIOD OF FREEZING RAIN ACROSS THE
TERMINALS...BUT SNOW AND SLEET MAY MIX IN AT TIMES. MAY NEED TO
MOVE START TIME UP SLIGHTLY BUT 10Z LOOKS TO BE THE EARLIEST IN
THE CHICAGO AREA AND 09Z OR SO OUT TOWARDS RFD. PRECIPITATION
INTENSITY LOOKS LIGHT BUT SOME MINOR GLAZING OR SLUSHY
ACCUMULATION IS POSSIBLE DURING THE MORNING BEFORE TEMPERATURES
WARM WELL ABOVE FREEZING. CIGS WILL ALSO QUICKLY DROP WITH LOW END
MVFR LIKELY AND IFR POSSIBLE MONDAY MORNING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* MEDIUM-HIGH CONFIDENCE IN MVFR CIGS RETURNING MID/LATE
MORNING...MEDIUM CONFIDENCE IN TIMING OF ARRIVAL/DEPARTURE.
* HIGH CONFIDENCE IN WIND TRENDS.
* MEDIUM CONFIDENCE IN PRECIP ARRIVING MONDAY MORNING...LOW-MEDIUM
CONFIDENCE IN TIMING...MEDIUM CONFIDENCE IN PRECIP TYPE TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
324 AM CDT
HIGH PRESSURE IS MOVING SOUTHEASTWARD TOWARD THE WESTERN GREAT LAKES
THIS MORNING WHILE A WEAK SURFACE LOW MOVES ACROSS EASTERN ONTARIO.
A TIGHT PRESSURE GRADIENT IS IN PLACE BETWEEN THESE TWO SYSTEMS WITH
STRONG NORTH-NORTHWEST WINDS BLOWING ACROSS MUCH OF THE CENTRAL AND
NORTHERN SECTIONS OF LAKE MICHIGAN. WINDS WILL DIMINISH THROUGH THE
MORNING ACROSS MOST OF THE LAKE AS THE HIGH MOVES OVERHEAD BUT THERE
WILL BE ENOUGH OF A PRESSURE GRADIENT IN PLACE TO THE SOUTH OF THE
HIGH OR ACROSS SOUTHERN LAKE MICHIGAN TO KEEP SLIGHTLY HIGHER WIND
SPEEDS GOING. WIND DIRECTION WILL SHIFT FROM NORTH-NORTHWEST TO EAST
THEN SOUTHEAST INTO THIS EVENING. SPEEDS WILL THEN INCREASE ACROSS
THE LAKE THIS EVENING AS THE HIGH DEPARTS TO THE EAST AND SURFACE
LOW PRESSURE MOVES EASTWARD ACROSS THE DAKOTAS AND ACROSS LAKE
SUPERIOR AND THE U.P. OF MICHIGAN BY MONDAY NIGHT. WILL GO AHEAD AND
EXTEND THE SMALL CRAFT FOR THE INDIANA NEARSHORE WATERS THROUGH LATE
AFTERNOON TODAY WITH WAVES EXPECTED TO STAY UP WITH THE NORTH TO
NORTHEAST WINDS. WILL ALSO ISSUE A SMALL CRAFT FOR THE ILLINOIS
NEARSHORE WATERS AS THE LONG FETCH OF NORTH THEN NORTHEAST WINDS
WILL BUILD WAVES THIS MORNING. WAVES WILL SUBSIDE LATER IN THE
AFTERNOON BUT WINDS WILL PICK UP TO SMALL CRAFT ADVISORY THRESHOLDS
DURING THE MID OR LATE EVENING WITH WAVES AGAIN BUILDING. WITH THIS
IN MIND WILL RUN THE SMALL CRAFT OUT THROUGH MONDAY MORNING THOUGH
THERE COULD BE A SHORT PERIOD WHERE WAVES FALL BELOW CRITERIA LATE
TODAY AND BEFORE WINDS COME UP ABOVE CRITERIA THIS EVENING.
A FURTHER SHIFT TO SOUTHWEST THEN WEST WINDS WILL OCCUR MONDAY
EVENING. COLDER AIR WILL SPREAD IN INTO TUESDAY AS THE LOW PASSES
AND THE PRESSURE GRADIENT WILL FURTHER STRENGTHEN LEADING TO A
PERIOD OF WEST TO NORTHWEST GALES...LIKELY IN THE 35-40 KT RANGE
STARTING MONDAY EVENING. RIGHT NOW MAINLY THE CENTRAL AND SOUTHERN
PORTIONS OF THE LAKE WILL SEE GALES WHILE THE FAR NORTH REMAINS
UNCERTAIN WITH THE EXPECTED TRACK OF THE LOW SHIFTING SLIGHTLY NORTH
AND SOUTH WITH RECENT FORECAST GUIDANCE. A FURTHER NORTH SOLUTION
WOULD RESULT IN A BETTER CHANCE OF THE NORTHERN THIRD SEEING GALES
AS WELL. SPEEDS WILL EASE LATER TUESDAY AFTERNOON BUT BE SLOW TO
REALLY QUIET DOWN THANKS TO THE LOW SLOWING AS IT PULLS OFF TO THE
EAST AND ANOTHER AREA OF HIGH PRESSURE NOSING INTO THE CENTRAL AND
NORTHERN PLAINS. THE FLOW THEN WEAKENS INTO FRIDAY WITH MAINLY A
NORTH TO NORTHEAST WIND EXPECTED THROUGH NEXT WEEKEND.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
647 AM CDT SUN MAR 17 2013
.SYNOPSIS...
ISSUED AT 335 AM CDT SUN MAR 17 2013
LATEST SFC ANALYSIS WAS INDICATING LARGE AND SEASONABLY STRONG RIDGE
COMPLEX ENGULFING MUCH OF THE UPPER MIDWEST WITH A NEAR 1030 MB
CENTER JUST NORTH OF THE NORTHWEST CORNER ON MN. SOUTHEAST RETURN
FLOW AND SFC PRESSURE GRADIENT TIGHTENING AND ORGANIZING ACRS THE
NORTHWESTERN HIGH PLAINS IN A REGION ALSO BATHED BY ROBUST PRESSURE
FALLS. ALOFT...WATER VAPOR IMAGERY WAS INDICATING A VIGOROUS UPPER
LEVEL WAVE ROLLING IN OFF THE PACIFIC AND ACRS OR/WA ATTM WITH AN
ASSOCIATED BAROCLINIC LEAF PLUME TO THE LEE OF IT ACRS THE WESTERN
ROCKIES. TO THE SOUTH ALONG TIGHTER LLVL BAROCLINIC RIBBON...AN
ISENTROPIC LIFT PRECIP EVENT WAS ONGOING ACRS KS...MO AND INTO
SOUTHERN IL.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 335 AM CDT SUN MAR 17 2013
TODAY...THE ABOVE MENTIONED STRONG RIDGE OF HIGH PRESSURE WILL LOOK
TO SQUEEZE EASTWARD ACRS THE WESTERN GRT LKS TODAY. AS IT DOES...
IT/S DRYING NORTHEAST TO EASTERLY FETCH IN THE BOUNDARY LAYER OR EVEN
DEEPER SHOULD KEEP MOST OF THE OVERRUNNING PRECIP OFF THE UPGLIDE
PROCESS TO THE SOUTH OF THE CWA. BUT WILL KEEP THE ONGOING MENTION
OF SPRINKLES OR A SLIGHT CHC OF LIGHT RAIN IN THE FAR SOUTH THIS
AFTERNOON. CLOUD COVER AND IT/S EFFECT ON TEMPS THE MAIN CHALLENGE
TODAY. THE RAP SEEMS TO HAVE SOME HANDEL ON CURRENT LLVL STRATUS
TRENDS PUSHING SOUTHWARD. AFTER MUCH OF THESE LOWER CLOUDS PUSH
ALMOST OUT OF THE DVN CWA...THE VEERING NORTHERLY FLOW SUGGESTED
BY THE RAP THEN SLOSHES BACK SOME LOWER LEVEL STRATUS BACK ACRS
MUCH OF THE DVN CWA FROM THE EAST AND NORTHEAST THIS MORNING UNDER
THE ONGOING AND SUBSTANTIAL TRAPPING INVERSION BASED AT H85 TO H75
MB. WITH PLUME OF MID AND UPPER LEVEL CLOUDS STREAMING OFF THE
OVERRUNNING PRECIP AND CONVECTION ACRS KS INTO MO...WITH THE CHANCE
OF THE STRATUS COMING BACK WILL KEEP THE FLAVOR OF THE DAY MOSTLY
CLOUDY ALTHOUGH SOME PEAKS OF SUN AT TIMES PROBABLE NORTH OF I80.
WILL KEEP HIGH TEMPS MAINLY IN THE 30S FOR A CHILLY ST PATRICK/S
DAY...BUT AREAS ALONG AND SOUTH OF I80 MAY GET NEAR 40 WITH SOME
CLOUD THINNING AT TIMES.
TONIGHT...THE DVN CWA TO BE MAINLY IN BETWEEN TWO LIFTING/FORCING
PROCESSES FOR MUCH OF THE NIGHT. THE ABOVE MENTIONED VIGOROUS UPPER
LEVEL WAVE CURRENTLY ACRS THE PACIFIC NORTHWEST WILL CONTINUE TO DIG
ACRS THE NORTHERN PLAINS AND MO RVR VALLEY THROUGH 12Z MON...WITH
UPPER LEVEL TROFFINESS EXTENDING ALL THE WAY DOWN INTO THE
SOUTHEASTERN PLAINS. CONCEPTUALLY THIS SHOULD ALLOW LLVL CYCLOGENESIS
BLOSSOM ACRS THE SOUTHEASTERN PLAINS AN UP THE LOWER TO MID MS RVR
VALLEY. NORTHWESTERN REACHING FLANK OF DEF ZONE PRECIP OFF THIS
FEATURE MAY CLIP THE SOUTHERN AND SOUTHEASTERN CWA THIS EVENING AND
INTO THE OVERNIGHT...BUT DRY LOW TO MID LEVELS WILL HAVE TO BE
OVERCOME. WILL KEEP CHC POPS IN THESE AREAS FOR LIGHT RAIN THIS
EVENING...BECOMING MIXED WITH SNOW OR SLEET INTO EARLY MON MORNING
AS EVAPO COOLING PROCESSES HAVE THEIR AFFECT. SFC TEMPS IN THESE
AREAS WILL BE MARGINAL FOR ANY FREEZING RAIN THREAT AND WILL NOT
MENTION. BUT THE MAIN FORCING EVENT IN VIEW OF THE APPROACHING
DIGGING WAVE WILL LOOK TO OCCUR ACRS THE NORTHEASTERN PLAINS INTO MN
AND IA LATER TONIGHT. DEEPENING SFC LOW PRESSURE TO UNDER 1000 MB TO
ROLL OUT OF THE DAKOTAS AND INTO NORTHWESTERN MN BY 12Z MON. THE
TROF ALMOST TAKING A NEG TILT AS IT DOES SUGGESTS A STRONGLY FORCED
EVENT ACRS THE UPPER MS RVR VALLEY REGION. ASSOCIATED PRECIP SWATH
AHEAD OF THIS PROCESS WILL LOOK TO PUSH ACRS IA AND INTO THE WESTERN/
NORTHWESTERN THIRD OF THE DVN CWA AFTER 08Z MON MORNING MAINLY IN
THE FORM OF SNOW. UPWARD VERTICAL VELOCITIES AND THERMODYNAMIC
PROFILES SUGGEST A BURST OF HEAVY WET SNOW POSSIBLE INTO THE FAR
NORTHWESTERN CWA WHERE UP TO AN INCH OF SNOW MAY OCCUR BY 12Z MON
NORTHWEST OF A CEDAR RAPIDS...TO MANCHESTER IA LINE. UP TO A HALF
INCH POSSIBLE ALONG AND NORTHWEST OF AN IOWA CITY...TO DYERSVILLE
LINE. STILL RATHER MILD SFC/GROUND TEMPS TO ACT AS AN ACCUMULATION
INHIBITOR AND PROMOTE COMPACTION AND MELTING EVENTUALLY. BUT SNOW
RATES BEFORE THE SUN RISES MAY STILL OVERCOME THIS FOR A WHILE TO
ALLOW THE POTENTIAL ACCUMS MENTIONED ABOVE. REST OF THE EVENT COVERED
IN DISCUSSION BELOW. ..12..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 17 2013
SNOW AMOUNTS MONDAY MORNING WILL BE THE MAIN CONCERN FOR THE LONG
TERM. AFTER MONDAY NORTHWEST FLOW TO DOMINATE THE REGION KEEPING
COLD AND DRY CONDITIONS OVER THE AREA INTO THE WEEKEND.
A SHORTWAVE OVER THE PACIFIC NORTHWEST EARLY THIS MORNING IS PROGGED
TO MOVE THROUGH THE MID AND UPPER MISSISSIPPI VALLEY MONDAY. THE
S/W WILL DRAG A STRONG COLD FRONT THROUGH THE REGION MONDAY
AFTERNOON AND EVENING WITH VERY COLD TEMPERATURES RUSHING INTO THE
REGION MONDAY AFTERNOON/NIGHT. THE FORECAST MODELS ARE IN GOOD
AGREEMENT IN SPREADING THE SYNOPTIC FORCING AHEAD OF THIS SYSTEM
OVER THE CWFA MONDAY MORNING WITH THE BETTER FORCING CLIPPING THE
NORTHERN COUNTIES. WITH PW/S EXPECTED TO BE AROUND A HALF INCH OR
SO QPF AMOUNTS OF 1 TO 2 TENTHS OF AN INCH LOOK REASONABLE BETWEEN
12Z AND 18Z. H8 TEMPS MONDAY MORNING WILL BE JUST BELOW ZERO
SUPPORTING SNOW RATIOS AROUND 10 TO 1 EARLY MONDAY MORNING WITH
RATIOS INCREASING TO 15 TO 1 BY LATE MORNING AS THE COLDER AIR
REACHES THE AREA. THE EXPECTED QPF AND SNOW RATIOS SUPPORT SNOWFALL
AMOUNTS IN THE 1 TO 2 INCH RANGE /STORM TOTAL/ NORTH OF I80 WITH THE
LOWER AMOUNTS NEAR I80 AND THE HIGHER AMOUNTS ALONG THE HIGHWAY 20
CORRIDOR. THE BIGGEST IMPACTS FROM THE SNOW MAY BE THE TIMING AND
LOW VISIBILITIES. THE SNOW WILL IMPACT THE MORNING COMMUTE
ESPECIALLY OVER EAST CENTRAL IOWA BUT SURFACE TEMPERATURES DURING
THE SNOW SHOULD BE IN THE UPPER 20S TO LOW 30S SUGGESTING MOST OF
THE SNOW WILL HAVE A DIFFICULT TIME ACCUMULATING ON ROADS. THE
OTHER AREA OF CONCERN WILL BE REDUCED VISIBILITIES. MODELS ARE
SHOWING A NARROW BAND OF FGEN WITH GOOD VERTICAL CONTINUITY AND ON
THE GRADIENT OF STEEPER MID LEVEL LAPSE RATES SUGGESTING A NARROW
BAND OF ENHANCED SNOWFALL RATES. IT ALSO APPEARS THAT THE THERMAL
PROFILES WILL SUPPORT DENDRITIC FLAKES DURING THE PERIOD OF ENHANCED
FORCING. IF THESE CONDITIONS VERIFY THEN VISIBILITIES DROPPING TO A
HALF MILE OR LESS WILL BE POSSIBLE AT TIMES MONDAY MORNING.
THE ACCUMULATING SNOW WILL END BY NOON IN THE NORTHEAST AS THE
BETTER FORCING MOVES EAST OF THE AREA. COLDER AIR AND STRONGER WINDS
MOVE IN DURING THE AFTERNOON CAUSING FALLING TEMPERATURES DURING THE
MID TO LATE AFTERNOON OVER THE NORTHWEST COUNTIES. THE BRISK
CONDITIONS WILL CONTINUE OVER NIGHT AS A SURFACE LOW MOVES THROUGH
THE WESTERN GREAT LAKES AND HIGH PRESSURE BUILDS SOUTHEAST INTO THE
MID/LOWER MISSOURI VALLEY. LOWS TUESDAY MORNING ARE EXPECTED TO
RANGE FROM AROUND 10 IN THE NORTH TO THE MID 20S SOUTH.
THE REST OF THE WEEK LOOKS COLD AND DRY WITH NORTHWEST FLOW
REMAINING OVER THE AREA BETWEEN A BROAD EASTERN US TROF AND RIDGING
OVER THE WESTERN U.S./EASTERN PACIFIC. A REINFORCING SHOT OF COLD
AIR IS PROGGED TO MOVE INTO THE REGION TUESDAY NIGHT RESULTING IN
SINGLE DIGIT LOWS NORTH AND AROUND 20 IN THE SOUTH WEDNESDAY MORNING
AND HIGHS WEDNESDAY IN THE LOW TO MID 20S NORTH TO MID 30S SOUTH.
AFTER WEDNESDAY TEMPERATURES WILL MODERATE A LITTLE WITH HIGHS
EXPECTED TO BE IN THE 30S TO LOW 40S AND LOWS IN THE 20S BY FRIDAY
AND SATURDAY. BUT THESE TEMPERATURES ARE STILL WELL BELOW NORMAL AS
WE APPROACH THE LAST WEEK OF MARCH.
DLF
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 633 AM CDT SUN MAR 17 2013
EXPECT MVFR LEVEL STRATUS OF BKN TO OVC COVERAGE TO INCREASE BACK
OVER ALL OF THE TERMINALS EXCEPT MAYBE DBQ THIS MORNING AS LLVL
FLOW BECOMES MORE EASTERLY. THESE MVFR DECKS TO LINGER INTO EARLY
THIS AFTERNOON BEFORE THEY DIURNALLY RISE UP TO VFR LEVEL DECKS.
GOOD SFC VISIBILITY EXPECTED ALL DAY WITH EAST WINDS OF 10 TO 15
KTS. THEN CIGS MAY LOWER AGAIN TO AT LEAST MVFR LEVELS IN THE VCNTY
OF BRL BY MID EVENING AS SOME LIGHT RAIN OR RAIN MIXED WITH SNOW
DRAWS NEAR FROM THE SOUTH. BUT THE MAIN WEATHER MAKER TONIGHT IN
THE FORM OF A LOW PRESSURE STORM SYSTEM WILL PUSH EASTWARD ACRS
THE NORTHERN PLAINS AND UPPER MS RVR VALLEY. THIS SYSTEM WILL
BRING LIGHT TO MODERATE SNOW AND EVENTUAL IFR CONDITIONS INTO THE
VCNTY OF CID AND THEN DBQ LATE TONIGHT/AFTER 09Z MON MORNING. 12
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...12
SHORT TERM...12
LONG TERM...DLF
AVIATION...12
AREA FORECAST DISCUSSION
NWS TOPEKA KS
646 AM CDT SUN MAR 17 2013
...UPDATE TO AVIATION...
.DISCUSSION...
A MIX OF PRECIPITATION WAS OCCURRING ACROSS NORTH CENTRAL AND
NORTHEAST KANSAS NORTH OF INTERSTATE 70 AT 08Z. A MIX OF
RAIN...SLEET AND SNOW HAS BEEN OBSERVED. EXPECT THIS PRECIPITATION
TO MOVE OUT OF THE AREA LATER THIS MORNING. RUC AND SREF SUGGEST
SOME REDEVELOPMENT OF PRECIPITATION IN CENTRAL KANSAS LATER THIS
AFTERNOON AS SHORTWAVE MOVES OUT OF THE ROCKIES. COULD SEE SOME
LIGHT RAIN APPROACHING NORTH CENTRAL KANSAS BY EVENING. ACROSS THE
EAST CENTRAL THIS MORNING WILL SEE THE BEST CHANCES OF PRECIPITATION
SOUTH OF I-35 IN ZONE OF FRONTOGENESIS FROM SOUTH CENTRAL INTO EAST
CENTRAL KANSAS. THERMAL PROFILES WOULD SUGGEST THAT THIS
PRECIPITATION WILL BE ALL LIQUID. TEMPERATURES TODAY WILL ONLY RISE
INTO THE LOWER 40S FOR HIGHS.
SATELLITE WAS SHOWING AN UPPER LEVEL TROUGH MOVING ACROSS THE
PACIFIC NORTHWEST AND THIS SYSTEM WILL DEEPEN AND MOVE ACROSS THE
ROCKIES AND INTO THE NORTHERN AND CENTRAL PLAINS TONIGHT. FORCING
WILL BE MAXIMIZED TO THE NORTH OF THE NEBRASKA BORDER TONIGHT AS THE
PV ANOMALY MOVES ACROSS THE NORTHERN PLAINS...SO EXPECTING ONLY 30
TO 40 PERCENT CHANCES OF PRECIPITATION TONIGHT WITH LITTLE IN THE
WAY OF QPF. THERMAL PROFILES SUGGEST THAT PRECIPITATION WILL BE ALL
RAIN THIS EVENING THEN A MIX OF RAIN AND SNOW NORTH OF HIGHWAY 56
AND RAIN SOUTH. LOWS TONIGHT COOLING INTO THE LOWER TO MID 30S. THE
UPPER TROUGH AXIS SHOULD MOVE OUT OF EASTERN KANSAS TOWARD SUNRISE
MONDAY.
A DRY PERIOD IS EXPECTED FROM MONDAY THROUGH WEDNESDAY WITH A DRY
NORTHWEST FLOW. NEXT SHOT OF PRECIPITATION OCCURS THURSDAY THROUGH
FRIDAY AS WAA INCREASE ALONG WITH ISENTROPIC LIFT AHEAD OF AN
APPROACHING UPPER TROUGH. MODELS ALSO SUGGEST THAT PIECES OF ENERGY
WILL MOVE OUT OF THE ROCKIES ACROSS KANSAS DURING THIS PERIOD. THE
ECMWF IS COOLER WITH THE THERMAL PROFILES AND FORECAST SOUNDINGS
SUGGEST THAT IT WILL BE COLD ENOUGH FOR SNOW AND ALSO A RAIN AND
SNOW MIX. THIS STILL MAY CHANGE WITH LATER RUNS. THE SYSTEM MOVES
OUT LATE FRIDAY WITH DRY WEATHER FOR THE START OF THE WEEKEND.
53
&&
.AVIATION...
CONFIDENCE IN THIS FORECAST IS LOW. AREA OBSERVATIONS SUGGEST KMHK
IS ON THE EDGE OF MVFR CIGS WITH ANOTHER AREA IN SOUTHEAST KANSAS.
MODELS HAVE PERSISTENTLY TRIED TO BRING KTOP AND KFOE INTO MVFR
CIGS BUT THIS HAS NOT OCCURRED. WILL GO WITH PERSISTENCE AT KMHK
AND WAIT UNTIL AFTER 18Z FOR KTOP AND KFOE WHEN BETTER FORCING
ARRIVES...AND BRING ALL TERMINALS INTO IFR CIGS AS THE NEXT SYSTEM
NEARS. LIGHT PRECIP POSSIBLE THROUGH MUCH OF THE DAY WITH SLOWLY
INCREASING CHANCES FOR AN ALL LIQUID TYPE.
65
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
741 AM EDT SUN MAR 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 526 AM EDT SUN MAR 17 2013
LATEST GFS ANALYSIS SHOWS HIGH LATITUDE POSITIVE HEIGHT ANOMALIES
OVER GREENLAND AND N OF ALASKA WITH A W-E ELONGATED POLAR VORTEX TO
THE S DOMINATING MUCH OF CANADA. CENTER OF VORTEX WAS OVER HUDSON
BAY. SHORTWAVE TROF EXTENDING FROM THE CENTER HAS SWEPT E OF THE
UPPER GREAT LAKES DURING THE NIGHT. IN THE WAKE OF THE WAVE...850MB
TEMP WAS -23C ON 00Z KINL RAOB...AND LATEST RUC ANALYSIS SHOWS 850MB
TEMPS AROUND -20C OVER LAKE SUPERIOR. DESPITE STRONG OVERWATER
INSTABILITY...LES HAS BEEN POORLY ORGANIZED (NO REAL BANDING) AND
GENERALLY LIGHT TO PERHAPS ONLY MDT INTENSITY AT TIMES DESPITE DGZ
DOMINATING CONVECTIVE LAYER AND DESPITE KMQT VAD WIND PROFILE
SHOWING CLOUD TOPS TO 6-7KFT MSL AND NEARLY UNIDIRECTIONAL FLOW THRU
CLOUD DEPTH. DRY ADIABATIC LAPSE RATES BELOW INVERSION PER UPSTREAM
00Z KINL/CWPL SOUNDINGS IS PROBABLY A CONTRIBUTOR TO THE POOR
ORGANIZATION AS IS INFLUX OF DRIER AIR. GIVEN THE LACK OF
ORGANIZATION AND WEAK INTENSITY OF LES...OPTED TO CANCEL LES ADVY
NEAR LAKE SUPERIOR OVER THE E.
SFC HIGH PRES OVER NRN MN WILL QUICKLY MOVE ACROSS THE FCST AREA
TODAY. IN FACT...CENTER SHOULD BE OF THE AREA BY LATE AFTN. AS A
RESULT...ONGOING DIMINISHING LES WILL END W TO E AS NW WINDS BECOME
LIGHT/VRBL THEN SOUTHERLY AFTER SFC HIGH PASSES. MAY SEE AN
ADDITIONAL INCH OF FLUFFY SNOW E OF MARQUETTE IN THE MORNING BEFORE
THE LES ENDS. OTHERWISE...SKIES SHOULD TURN MOSTLY SUNNY W-E AFTER
WIND SHIFT TO THE S FOLLOWING PASSAGE OF THE SFC HIGH PRES. THE DAY
WILL PROBABLY BEGIN MOSTLY SUNNY OVER THE SCNTRL WHERE DOWNSLOPING
IS ALREADY LEADING TO MOSTLY CLEAR SKIES. DESPITE INCREASING
SUNSHINE...HIGH TEMPS WILL ONLY REACH INTO THE 20S WITH 850MB TEMPS
RECOVERING TO -8C TO -12C IN THE AFTN.
DRY WEATHER WILL CONTINUE TONIGHT. HIGH AND THEN MID CLOUDS WILL BE
ON THE INCREASE AHEAD OF VIGOROUS SHORTWAVE THAT IS NOW MOVING
ACROSS THE PACIFIC NW INTO THE NRN ROCKIES. INCREASING CLOUDS AND
INCREASING SE WINDS WILL KEEP TEMPS FROM FALLING SIGNIFICANTLY. SOME
OF THE TRADITIONAL COLD SPOTS MAY DROP TO AROUND 10F...BUT MOST
AREAS SHOULD SEE MINS IN THE MID/UPPER TEENS WITH A SLIGHT RISING
TREND TO TEMPS LATE.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 526 AM EDT SUN MAR 17 2013
PRIMARY FOCUS HAS BEEN AND CONTINUES TO BE UPR TROUGH/LOW PRESSURE
SYSTEM MOVING ACROSS UPPER GREAT LAKES ON MONDAY. IN GENERAL MODELS
INDICATE ADVY SNOW EVENT FOR MUCH OF CWA...BUT AT LEAST AS OF THIS
MORNING DOES NOT APPEAR TO BE A BLOCKBUSTER MARCH STORM BY UPPER
LAKES STANDARDS. ONE REASON SYSTEM IS NOT AS STRONG AS IT COULD BE
IS GULF MOISTURE TRYING TO SURGE NORTHWARD IS INTERCEPTED BY SMALLER
AREA OF SFC-H85 LOW PRESSURE SLIDING FROM SOUTHERN PLAINS INTO OHIO
VALLEY. PWATS INTO THAT AREA ARE WELL OVR 200 PCT OF NORMAL WHILE
THEY STAY ONLY AROUND NORMAL INTO WISCONSIN AND UPR MICHIGAN. SECOND
REASON LARGER SCALE SYSTEM IMPACTING AREA ON MONDAY IS NOT AS STRONG
IS DUE TO LIMITED JET ENHANCEMENT/DEEPENING OF H5 LEVEL LOW AS IT
SLIDES ACROSS UPR LAKES REGION. LAST COUPLE RUNS OF GFS/GEM-NH HAVE
TRENDED A BIT DEEPER WITH SFC-H85 LOWS THOUGH AND THIS RESULTS IN A
WETTER TREND FM THE GFS...WITH 12HR QPF OF 0.25-0.30 INCH OVR MOST
OF WEST HALF OF CWA 18Z MONDAY THROUGH 06Z TUESDAY. LARGE SCALE
ENHANCEMENT FACTORS TO BOOST PRECIP ARE MINOR AS NAM/GFS INDICATE
BRIEF PERIOD OF MOISTURE ADVECTION 850-800MB WITH MINIMAL TEMP
ADVECTION IN THAT LAYER. ALSO THERE IS NO JET SUPPORT AND MINIMAL
FRONTOGENESIS SINCE TEMPERATURE GRADIENT SFC-H85 IS LACKING.
THUS...APPERS THAT MOISTURE ADVECTION AND INCREASING CYCLONIC FLOW
AROUND SFC-H85 LOWS WILL DRIVE THE SNOW. EXPECT MOST SNOW TO OCCUR
THROUGH 00Z TUESDAY OVR SW TIER AND 18-21Z MONDAY THROUGH 03Z
TUESDAY IN THE NORTH AND EAST CWA. CONSENSUS OF MODELS FAVOR THAT
TIMING AND THERE IS GOOD AGREEMENT FROM SREF MEMBERS AS WELL. ONE
MESOSCALE EFFECT THAT MAY RESULT IN MORE SNOW IS POSSIBLE LAKE
ENHANCEMENT WITH ESE BLYR WINDS ON THE KEWEENAW AS H85 TEMPS ARE AT
OR COLDER THAN -8C. SHOWED ENHANCED QPF/SNOW FOR KEWEENAW ON MONDAY
AFTN/EVENING TO ACCOUNT FOR THIS. SLR/S FOR THIS EVENT WILL NOT BE TOO
OFF FROM 16:1 CLIMATOLOGY MARK...IF ANYTHING MAY BE SLIGHTLY LOWER
BUT STILL ABOVE 10:1. OVERALL 3"/12HR SEEMS PROBABLE OVER MUCH OF THE
AREA WHICH IS ADVY CRITERIA. MAYBE MORE SNOW OVER FAR WEST AND ACROSS
KEWEENAW PENINUSLA. WPC WWD GRAPHICS INDICATE 4-6 INCHES FOR THOSE
AREAS...WHICH ACTUALLY LINES UP WELL WITH CURRENT FORECAST THINKING.
SINCE BULK OF SNOW OCCURS LATER IN THE 3RD PERIOD...WILL NOT ISSUE
ANY ADVISORIES FOR SYSTEM SNOW ON MONDAY YET.
LK EFFECT INCREASES ON MONDAY NIGHT INTO TUESDAY FOR AREAS FAVORED
BY WNW-NW FLOW. A MAJORITY OF SNOW FROM THE SYSTEM WILL LIKELY COME
DURING THAT TIME AND ADDITIONAL HEADLINES MAY BE NEEDED INTO
TUESDAY. NAM SOUNDINGS INDICATE DEPTH OF LK EFFECT CONVECTIVE LAYER
BUILDS THROUGHOUT THE NIGHT WITH EQL PEAKING OVER 10KFT BTWN 09Z-12Z
ON TUESDAY IN THE WESTERN CWA AND AROUND 15Z ON TUESDAY IN THE
NORTHEAST CWA. GFS /WHICH IS PREFERRED BY WPC WITH TIMING OF THE
SYSTEM DUE TO ITS CONSISTENCY/ SHOWS SIMILAR SETUP BUT IS SLIGHTLY
SLOWER WITH TIMING. SINCE SOUNDINGS INDICATE MAJORITY OF LK
CONVECTIVE LAYER WITHIN THE DGZ...SLR/S WILL PUSH WELL OVER 20:1.
STRONG WINDS OVER 25 KTS IN THE BLYR WILL CUT SLR/S DOWN SLIGHTLY
THOUGH. HIGH SLR/S WITH PERSISTENT CONVERGENCE AND MORE THAN AMPLE
OVER-WATER INSTABILITY WILL RESULT IN AT LEAST MODERATE LK EFFECT
SNOWS FOR FAVORED AREAS. HINT AT REINFORCING SHOT OF COLDER AIR
LATER TUESDAY NIGHT SO AFTER SLIGHT DIMINISHING TREND INTO TUESDAY
EVENING MAY SEE ANOTHER UPTICK IN LK EFFECT AS THE TROUGH AND COLDER
AIR ARRIVE.
STEADY STATE LK EFFECT SETUP CONTINUES INTO WEDNESDAY NIGHT AND
KEPT CATEGORICAL POPS GOING FOR NW FLOW AREAS. SEVERAL INCHES OF
FLUFFY LK EFFECT SNOW SHOULD ACCUMULATE WEDNESDAY AND WEDNESDAY
NIGHT. ACCUMS IN SOME AREAS LIKELY WILL EXCEED A FOOT IN THE 48 HOUR
TIME FRAME TUESDAY THROUGH WEDNESDAY. OTHER HAZARD WILL BE BLOWING
SNOW AND REDUCED VSBY OVER MUCH OF THE EASTERN CWA AS NW WINDS GUST
OVER 25 KTS THROUGH WEDNESDAY. OCCASIONAL WHITEOUTS SEEM LIKELY...
ESPECIALLY ALONG LK SUPERIOR TUESDAY AFTN THROUGH WEDNESDAY MORNING.
WILL CONTINUE TO MENTION THE PROLONGED PERIOD OF MODERATE-HEAVY LK
EFFECT SNOW AND CONSIDERABLE BLSN IN THE HAZARDOUS WEATHER OUTLOOK.
OUR BACKLOADED WINTER JUST WILL NOT LET GO. LK EFFECT GRADUALLY
DIMINISHES INTO THURSDAY AS LOW PRESSURE TROUGH OVER THE REGION
BEGINS TO RELAX. PROBABLY CAN NOT COUNT OUT LGT LK EFFECT OR FLURRIES
INTO AT LEAST FIRST PART OF NEXT WEEKEND THOUGH AS ECMWF/GFS SHOW
WEAK ONSHORE WINDS CONTINUING BTWN HIGH PRESSURE OVER SCNTRL CANADA
AND TROUGHING OVER EASTERN CANADA/NEW ENGLAND. AFTER TEMPS NEAR 30
DEGREES ON MONDAY AHEAD OF DEVELOPING LOW PRESSURE SYSTEM...DAYTIME
TEMPS FOR THE REST OF THE WEEK WILL BE BLO NORMAL. ONLY GRADUAL
WARMING INTO 30S FOR NEXT WEEKEND.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 740 AM EDT SUN MAR 17 2013
HIGH PRES QUICKLY SLIDING ACROSS THE UPPER GREAT LAKES TODAY WILL
BRING AN END TO LINGERING -SHSN/FLURRIES AT KCMX/KSAW THIS MORNING.
IN FACT...WITH WINDS BECOMING S/SE AFTER PASSAGE OF SFC HIGH PRES...
EXPECT STRATOCU (MVFR CIGS HAVE RECENTLY DEVELOPED AT KIWD/KCMX/KSAW
DUE TO FALLING INVERSION) WILL CLEAR OUT FROM W TO E THIS MORNING.
DRY LOW-LEVELS WILL LINGER TONIGHT...RESULTING IN VFR CONDITIONS
CONTINUING. HOWEVER...UPSLOPE SSE FLOW OFF LAKE MI COULD RESULT IN
MVFR CIGS REDEVELOPING AT KSAW. WILL BE SOMETHING TO MONITOR.
OTHERWISE...TIGHTENING PRES GRADIENT AND NOCTURNAL INVERSION WILL
LIKELY LEAD TO LLWS AT ALL 3 SITES TONIGHT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 526 AM EDT SUN MAR 17 2013
WITH HIGH PRES QUICKLY MOVING ACROSS LAKE SUPERIOR TODAY...EXPECT A
PERIOD OF LIGHT WINDS UNDER 15KT. THE DIMINISHING WINDS/WAVES WILL
BRING AN END TO HVY FREEZING SPRAY EARLY THIS MORNING. AS THE HIGH
CONTINUES E...REACHING NEW ENGLAND MON...LOW PRES EMERGING OVER THE
WRN DAKOTAS THIS AFTN WILL TRACK E...REACHING THE UPPER GREAT LAKES
MON NIGHT. TIGHT PRES GRADIENT BTWN THE DEPARTING HIGH AND
APPROACHING LOW WILL BRING SE WINDS UP TO 30KT TONIGHT AND MON. SOME
GALE FORCE GUSTS TO 35KT WILL BE POSSIBLE LATE TONIGHT/MON OVER
PORTIONS OF NCNTRL AND ERN LAKE SUPERIOR. AFTER THE LOW EXITS TO THE
E...NORTHWEST GALES WILL DEVELOP FROM W TO E LATE MON NIGHT/TUE.
THE GALES WILL THEN CONTINUE INTO WED OVER THE E HALF OF THE LAKE.
WINDS WILL SLOWLY DIMINISH TO UNDER 25KT FROM W TO E WED NIGHT/THU.
THE COMBINATION OF COLD AIR/STRONG WINDS/HIGH WAVES WILL LEAD TO
PERIODS OF HVY FREEZING SPRAY TUE THRU WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 9 AM EDT THIS MORNING FOR
LSZ245-248>251-265>267.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS DULUTH MN
1006 AM CDT SUN MAR 17 2013
.UPDATE...
THE FORECAST WAS UPDATED THROUGH TONIGHT. THE MAIN CHANGES
WERE TO SKY COVER. IT APPEARS THE COMBINATION OF BKN/OVC MID/LOW
LEVEL CLOUDS IN WESTERN MINNESOTA MOVING TOWARDS THE
NORTHLAND AND INCREASING LOW LEVEL CLOUDS ACROSS THE EASTERN
FORECAST AREA THIS AFTERNOON WILL RESULT IN A GENERALLY INCREASING
CLOUD COVER TREND THROUGH THE AFTERNOON. THE 12Z NAM12 SOUNDINGS
ARE SHOWING THAT CONVECTIVE TEMPERATURES WILL BE REACHED EARLY
THIS AFTERNOON AND LIKELY RESULT IN AT LEAST SOME SCATTERED LOW
LEVEL CLOUDS ACROSS THE EASTERN FORECAST. THIS SHOWS UP TOO IN
RECENT HRRR MODEL RUNS. ALSO...THERE IS PLENTY OF BKN/OVC MID/LOW
LEVEL CLOUDS MOVING THROUGH WESTERN MINNESOTA AND THE EASTERN
DAKOTAS ON PATH TOWARDS THE NORTHLAND...AND THERE DOES NOT APPEAR
TO BE MUCH TO STOP IT AS THE HIGH PRESSURE OVER THE GREAT LAKES
CONTINUES TO MOVE EAST. RECENT MODEL GUIDANCE WAS ALSO SHOWING
LOWER HIGH TEMPERATURES TODAY...WHICH SHOULD MAKE SOME SENSE
CONSIDERING HOW COLD IT GOT THIS MORNING AND THE INCREASING CLOUD
COVER TODAY. THEREFORE...DECREASED THE HIGHS A BIT. UPDATED THE
PCPN TIMING LATE THIS AFTERNOON AND INTO TONIGHT A BIT...BUT DID
NOT YET CHANGE THE PCPN/SNOWFALL FORECAST. I WILL LOOK MORE INTO
THIS EARLY THIS AFTERNOON. THE NIGHT SHIFT BRIEFED ME ABOUT THE
DIFFERENCES THE MODELS HAVE IN THE TRACK OF THE SURFACE LOW WITH
THE APPROACHING WINTER STORM SYSTEM. THE 00Z/06Z NAM12 STILL HAD A
MUCH MORE NORTHERN TRACK THAN THE OTHER MODELS...BUT I AM HAPPY TO
SEE THAT THE RECENT 12Z NAM12 CAME IN WITH A TRACK MUCH MORE SOUTH
AND SIMILAR TO THE ECMWF AND GFS. HOPEFULLY THE OTHER 12Z MODEL
RUNS WILL FINALLY FIND SOME CONSENSUS...ESPECIALLY THE GEM...WHICH
IS THE OTHER OUTLIER DUE TO ITS MORE SOUTHERN TRACK.
&&
.PREV DISCUSSION... /ISSUED 640 AM CDT SUN MAR 17 2013/
AVIATION...12Z TAFS.
VFR UNTIL ABOUT 03Z WHEN MVFR CIGS/VSBYS IN LIGHT SNOW BEGIN TO
SPREAD ACROSS THE TERMINALS FROM W TO E. THIS IS IN RESPONSE TO
THE LARGE LOW PRESSURE SYSTEM THAT WILL MOVE OVER MN MONDAY.
PREV DISCUSSION... /ISSUED 341 AM CDT SUN MAR 17 2013/
SHORT TERM...
TODAY THROUGH MONDAY AFTERNOON...
POTENT WINTER SYSTEM EXPECTED TO IMPACT THE NORTHLAND BEGINNING
TONIGHT AND LASTING THROUGH THE DAY MONDAY.
MAIN CONCERNS IN THE SHORT TERM ARE FOCUSED AROUND ACCUMULATING
SNOW...LOCALLY HEAVY AMOUNTS POSSIBLE...BLOWING SNOW AND GUSTY
WINDS.
A WINTER WEATHER ADVISORY IS IN EFFECT FOR THE ENTIRE NORTHLAND
FROM LATE THIS EVENING THROUGH MONDAY NIGHT.
HIGH PRESSURE CURRENTLY SITUATED OVER FAR NE MN/WRN ONTARIO IS
ALLOWING FOR MOSTLY CLEAR SKIES AND VERY COLD TEMPERATURES ACROSS
THE REGION THIS MORNING. A FEW LOCATIONS IN NE MN HAVE DROPPED
BELOW -20 F...WITH MOST AREAS SEEING WIDESPREAD 0 TO -10 DEG
READINGS. TEMPS SHOULD REBOUND RATHER QUICKLY WITH A HIGH SUN
ANGLE AND A RETURN SOUTHERLY FLOW ON THE WEST SIDE OF THE HIGH AS
IT MOVES EWD THROUGH THE GREAT LAKES REGION. HIGHS TODAY WILL TOP
OUT IN THE 20S.
THIS AFTERNOON...A ROBUST SFC LOW WILL DEVELOP IN THE FRONT RANGE
OF THE NRN ROCKIES AND MOVE EWD INTO THE WRN DAKOTAS. AHEAD OF
THIS SYSTEM...STRONG WAA AND MOISTURE TRANSPORT WILL OCCUR WITH
THE HELP OF A ROBUST LLJ...APPROX 40-50 KT AT 2-3K FT. MOST OF THE
FORCING FOR THIS SYSTEM WILL COME FROM MESOSCALE PROCESSES...AS
THE SYNOPTIC DYNAMICS WILL BE LIMITED. THE COMBINATION OF STRONG
ISENTROPIC LIFT...WAA...AND MODEST MID LEVEL F-GEN WILL ALLOW A
WELL-DEFINED AREA OF ENHANCED SNOW TO DEVELOP ON THE LEADING EDGE
OF THE LOW PRESSURE SYSTEM. THE TRACK OF THE LOW WILL BE CRITICAL
IN DETERMINING WHERE THE HIGHEST SNOW AMTS SET UP. IN THE PAST FEW
DAYS...MODELS HAVE BEEN TRENDING THE TRACK FURTHER NWD ACROSS FAR
NERN MN. HOWEVER...THE PAST COUPLE RUNS OF THE GEM AND ECMWF HAVE
TRENDED BACK TO THE SOUTH. THIS WOULD PLACE A GOOD PORTION OF NERN
MN IN THE FAVORABLE AREA OF THE DEFORMATION ZONE AS THE LOW MOVES
E/NEWD. THE HEAVIEST SNOW RATES WILL LIKELY BE SEEN WITH THE
INITIAL BAND/AREA OF SNOW SUNDAY NIGHT/MONDAY MORNING. THERE IS
SOME INDICATION OF A DRY SLOT WRAPPING AROUND AND PUSHING IN FROM
THE SW MON AFTERNOON...WHICH COULD LIMIT THE AMT OF SNOW SOUTH OF
HIGHWAY 2 IN MN AND AREAS TO THE EAST. THE MOST FAVORABLE AREA OF
HEAVY SNOW WILL BE FROM THE IRON RANGE NWD...DUE TO A PROLONGED
PERIOD IN THE DEFORMATION ZONE...AND ALONG THE ELEVATED TERRAIN OF
THE ARROWHEAD FROM TWO HARBORS NWD...DUE TO LAKE/TERRAIN
ENHANCEMENT. MOST AREAS TO THE SOUTH WILL LIKELY SEE 3-5
INCHES...WITH CLOSER TO 4-7 INCHES ACROSS THE NORTH AND ALONG THE
NORTH SHORE. THIS IS AN INITIAL ASSESSMENT...AND
MORNING/AFTERNOON MODEL GUIDANCE WILL SHED MORE LIGHT ON POTENTIAL
SNOW AMOUNTS. HIGHER AMTS NOT OF THE QUESTION...AND UPGRADES TO
WINTER STORM WARNINGS ARE POSSIBLE.
THE OTHER CONCERN WITH THIS SYSTEM WILL BE THE GUSTY W/NW WINDS
AND AREAS OF BLOWING SNOW...CAUSING REDUCED VSBYS AND DANGEROUS
TRAVEL CONDITIONS. A TIGHT PRESSURE GRADIENT ON THE WRN SIDE OF
THE DEPARTING LOW MON AFTERNOON WILL PRODUCE GUSTS UP TO 30 MPH AT
TIMES. LOCALLY HIGHER GUSTS WILL BE POSSIBLE...AND POTENTIALLY
PRODUCE NEAR WHITE-OUT CONDITIONS...ESPECIALLY FROM LEECH LAKE TO
LAKE MILLE LACS AND AROUND THE TWIN PORTS AREA WHERE HIGHER GUSTS
ARE LIKELY.
LONG TERM...
MONDAY NIGHT THROUGH SATURDAY...
THE VERTICALLY STACKED SYSTEM MOVES OVER NORTHERN LAKE SUPERIOR
BY 12Z TUESDAY. WILL CONTINUE TO SEE LIGHT SNOW IN THE CAA PATTERN
AND EMBEDDED SHORT WAVE ENERGY ROTATING AROUND THE LOW MONDAY
NIGHT. AS THIS SYSTEM SLOWLY LIFTS TO THE ENE INTO ONTARIO...COLD
AIR WILL CONTINUE TO SURGE INTO THE FA WITH MORE SHORT WAVE
ENERGY. HOWEVER...DRY HIGH PRESSURE IS WORKING INTO THE FA FROM
THE NORTHERN PLAINS. EXPECT THE LIGHT SNOW TO BE LIMITED TO THE
ARROWHEAD AND SOME FLURRIES IN NW WI. DIALED BACK ON THE LES
MENTION AS MODEL DIFFERENCES MAKE IT DIFFICULT TO GO WITH HIGHER
POPS/QPF/SNOW AMOUNTS. LITTLE CHANGE TO THE UPPER LEVEL PATTERN
WITH A WNW FLOW AND HIGH PRESSURE AT THE SFC. ONLY MENTION OF
LIGHT SNOW WILL BE ALONG THE SOUTH SHORE OF LS OVER ASHLAND AND
IRON COUNTIES THROUGH THURSDAY. QUIET WEATHER THURSDAY NIGHT
THROUGH SATURDAY.
&&
.POINT TEMPS/POPS...
DLH 21 19 27 5 / 0 90 90 20
INL 21 15 24 -1 / 10 100 90 20
BRD 23 21 24 2 / 10 90 70 10
HYR 26 17 29 4 / 0 80 90 20
ASX 25 18 32 10 / 0 80 90 50
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY FROM 7 AM MONDAY TO 5 AM CDT TUESDAY FOR
MNZ012-020-021.
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO MIDNIGHT CDT
MONDAY NIGHT FOR MNZ010-018-025-026-033>036.
WINTER WEATHER ADVISORY FROM 4 AM MONDAY TO MIDNIGHT CDT MONDAY
NIGHT FOR MNZ011-019-037-038.
WI...WINTER WEATHER ADVISORY FROM 4 AM MONDAY TO MIDNIGHT CDT MONDAY
NIGHT FOR WIZ001-006-007.
WINTER WEATHER ADVISORY FROM 7 AM MONDAY TO MIDNIGHT CDT MONDAY
NIGHT FOR WIZ002>004-008-009.
&&
$$
SHORT TERM...GROCHOCINSKI
LONG TERM....DAP
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1017 AM CDT SUN MAR 17 2013
.SYNOPSIS...
ISSUED AT 247 AM CDT SUN MAR 17 2013
IN THE ANALYSIS OF THE 06Z MSL PLOT...LOW PRESSURE WAS CENTERED OVER
SOUTHWEST MONTANA WITH A WARM FRONT DRAPED THROUGH CENTRAL WYOMING
TO EASTERN COLORADO. ALSO...A COLD FRONT STRETCHED FROM THE LOW
THROUGH EASTERN BRITISH COLUMBIA TO THE GULF OF ALASKA.
OTHERWISE...HIGH PRESSURE DOMINATED THE SCENE IN THE WESTERN GREAT
LAKES AND THE NORTHERN PLAINS NEAR THE CANADIAN BORDER.
&&
.UPDATE...
ISSUED AT 1017 AM CDT SUN MAR 17 2013
FORECAST HAS BEEN UPDATED TO SLOW THE TIMING OF RAIN SHOWERS INTO
THE PANHANDLE UNTIL EARLY AFTERNOON AND TO EXTEND THE COVERAGE OF
FREEZING DRIZZLE FOR ANOTHER SEVERAL HOURS IN THE COUNTIES
SURROUNDING THE HIGHWAY 83 CORRIDOR.
AT 15Z...THE WARM FRONT REMAINS OUT ALONG THE FRONT RANGE OF THE
ROCKIES...WITH THE COLD FRONT OUT OVER NORTHWEST WYOMING AND
IDAHO. AS THE PRESSURE GRADIENT TIGHTENS AHEAD OF THE
SYSTEM...WINDS HAVE BEEN INCREASING ACROSS THE LOCAL AREA. THERE
ARE SOME WEAK AND VERY SCATTERED RADAR ECHOES BEING PICKED UP
OVER THE PANHANDLE AHEAD OF THE WARM FRONT...BUT DON/T EXPECT ANY
MEASURABLE RAINFALL UNTIL THE FRONT GETS CLOSER AFTER 18Z.
ALSO...WITH THE STRATUS HANGING IN...TEMPERATURES HAVE BEEN SLOW
TO WARM OVER THE EASTERN 2/3RDS OF THE FORECAST AREA...WITH MOST
OF THESE AREAS REMAINING BELOW FREEZING. ALTHOUGH RADAR IS NOT
SHOWING MUCH...AND ASOS/AWOS OBSERVATIONS ARE NOT PICKING UP ON
THE DRIZZLE...BELIEVE THE LOWERED VISIBILITIES IS WHERE THE
FREEZING DRIZZLE IS OCCURRING...ALTHOUGH IT IS VERY LIGHT. IR
SATELLITE ALSO SHOWS CLOUD TOPS WARMER THAN -10C SO ANYTHING
OCCURRING WOULD BE DRIZZLE. AS WINDS CONTINUE TO PICK UP...WOULD
EXPECT THE STRATUS TO BEGIN BREAKING UP YET THIS MORNING AND THE
DRIZZLE COME TO AN END.
WIND ADVISORY LOOKING ON TRACK...AS WINDS SHOULD CONTINUE TO PICK
UP INTO THE AFTERNOON.WITH THE RAP INDICATING 850MB WINDS AT 55KTS
THIS AFTERNOON OVER NORTH CENTRAL NEBRASKA...CONTINUE TO THINK
GUSTS TO 45 MPH ARE LIKELY.
UPDATE ISSUED AT 640 AM CDT SUN MAR 17 2013
NORTH PLATTE AND PROBABLY OGALLALA AND IMPERIAL HAVE BEEN PICKING
UP SOME DRIZZLE. WITH TEMPERATURES BELOW FREEZING THROUGH THE
SOUTHWEST...FREEZING DRIZZLE IS NOT OUT OF THE QUESTION THROUGH
ABOUT MID-MORNING.
&&
.SHORT TERM...(TODAY AND SUNDAY)
ISSUED AT 247 AM CDT SUN MAR 17 2013
AS THE WARM FRONT MAKES ITS WAY EASTWARD INTO WESTERN NEBRASKA...
AIR IS LIFTED INTO A HYDRO-STATICALLY UNSTABLE ENVIRONMENT AS
INDICATED BY FOLDING IN A CROSS-SECTION OF THETA-E. A LOOK AT
CONVECTIVE PARAMETERS INDICATES SOME INSTABILITY WITH PRECIPITABLE
WATER VALUES APPROACHING 0.5 INCH. FROM THAT...IT APPEARS THAT THERE
WILL BE AT LEAST ISOLATED THUNDERSTORMS EMBEDDED IN THE BROADER AREA
OF SHOWERS. THIS IS REFLECTED FAIRLY WELL IN THE HOURLY
PRECIPITATION SHOWN BY THE RAP13 SHORT RANGE MODEL AND IN THE GFS
OUTPUT AND EVEN IN THE GEM REGIONAL AND EVEN THE NORTHERN HEMISPHERE
GEM. THE RESULT IS THAT WE HAVE FAIRLY HIGH CONFIDENCE THAT MUCH OF
CENTRAL AND WESTERN NEBRASKA WILL HAVE AT LEAST SCATTERED SHOWERS
THROUGHOUT THE AREA WITH ISOLATED THUNDERSTORMS THIS AFTERNOON
THROUGH LATE THIS EVENING IN SOUTHWEST NEBRASKA. THE COLD FRONT
COMING ACROSS LATE THIS EVENING WILL BRING A QUICK END TO ANY
PRECIPITATION SHORTLY AFTER 06Z.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 247 AM CDT SUN MAR 17 2013
MAINLY DRY CONDITIONS WITH NORTHWEST FLOW ALOFT TO START THE WEEK
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. GUSTY NORTHWEST WINDS
ARE EXPECTED IN THE WAKE OF THE SUNDAY NIGHT SYSTEM ON MONDAY.
GOOD MIXING COULD YIELD WIND SPEEDS NEAR WIND ADVISORY. OTHERWISE AN
ARCTIC FRONTAL BOUNDARY WILL OSCILLATE BACK AND FORTH FROM
NORTHEAST TO SOUTHWEST ACROSS THE AREA THROUGH MIDWEEK. THIS FRONT
WILL KEEP THE NORTHEAST SECTIONS OF THE AREA AROUND ONEILL QUITE
CHILLY...WITH TEMPERATURES MOSTLY BELOW NORMAL FOR THIS TIME OF
YEAR. FARTHER SOUTHWEST ACROSS WESTERN AND SOUTHWEST
NEBRASKA...SOMEWHAT WARMER CONDITIONS ARE EXPECTED...WITH
TEMPERATURES RIGHT AROUND NORMAL. ALL AREAS WILL BE BELOW AVERAGE
TEMPERATURE WISE BY THE END OF THE WEEK...AS THE ARCTIC FRONT
MOVES SOUTH IN RESPONSE TO STRONG SFC HIGH PRESSURE NOSING SOUTH
INTO THE NORTHERN PLAINS.
FOLLOWED THE GFS ENSEMBLE MEAN IN REGARDS TO PRECIP CHANCES...AND 30
TO 40 PERCENT SEEMS REASONABLE WEDNESDAY NIGHT THROUGH FRIDAY AS A
SIGNIFICANT DISTURBANCE DROPS SOUTHEAST INTO THE AREA. OPERATIONAL
MODELS HAVE BEEN STRUGGLING ON HOW TO HANDLE THIS ENERGY DROPPING
SOUTHEAST INTO THE AREA. THIS IS LIKELY DUE TO A BLOCKY TYPE UPPER
PATTERN. FELT THE GFS ENSEMBLE MEAN WAS THE WAY TO LEAN AT THIS
POINT...AND FOR WHAT IT/S WORTH...THE MEAN REPRESENTS THE
OPERATIONAL GFS OUTPUT BETTER THAN THE ECMWF. THIS WOULD BE A
WETTER SOLUTION FOR US...AND THE PRECIPITATION WOULD BE MOSTLY IN
THE FORM OF SNOW DUE TO COLD AIR IN PLACE. STAY TUNED.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 640 AM CDT SUN MAR 17 2013
LOW CLOUDS AND DRIZZLE HAVE DEVELOPED OVER PARTS OF SOUTHWEST
NEBRASKA...INCLUDING LBF AND POSSIBLY IML AND OGA. WITH TEMPERATURES
AT OR BELOW 32F...LIGHT FREEZING DRIZZLE IS A THREAT. CEILINGS ARE
ALSO BELOW 1000 FEET AGL IN THAT AREA WITH SOME AS LOW AS 200 FEET
AGL. THE FREEZING DRIZZLE SHOULD END BY 15Z AS TEMPERATURES
INCREASE. THERE IS MORE UNCERTAINTY WITH THE CEILING LIFTING TO
ABOVE 1000 FEET AGL. CONDITIONAL CLIMATOLOGY INDICATES THAT 18Z IS A
GOOD ESTIMATE AND THE SHORT RANGE FORECAST SIMULATIONS FAVOR THAT
TIME AS WELL.
ANOTHER ELEMENT WITH POTENTIAL IMPACT ON FLIGHT OPERATIONS IS WIND.
STRONG WIND AHEAD OF THE FRONT WILL BRING WINDY CONDITION BEGINNING
AS EARLY AS 16Z WITH WIND 190-210 INCREASING TO 26-28G34-38KT AT
ANW... VTN AND TIF. AT BBW...LBF...OGA AND IML THE SPEED WILL BE A
LITTLE LOWER AT 22-25G31-35KT.
ONE OTHER POTENTIAL PROBLEM COULD BE ISOLATED THUNDERSTORMS EMBEDDED
IN A BROADER AREA OF RAINSHOWERS THIS AFTERNOON AND EVENING. THE
COVERAGE OF THE THUNDERSTORMS WILL NOT BE HIGH...SO THE PROBABILITY
OF ANY ON SITE HAVING A THUNDERSTORM IS TOO LOW FOR INCLUSION IN THE
TERMINAL FORECASTS FOR LBF AND VTN.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 8 PM CDT /7 PM MDT/ THIS EVENING FOR NEZ005-
006-008-009-023>025-094.
WIND ADVISORY FROM 3 PM THIS AFTERNOON TO 10 PM MDT THIS EVENING
FOR NEZ004-022-056.
&&
$$
UPDATE1...SPRINGER
UPDATE2...BROOKS
SYNOPSIS...SPRINGER
SHORT TERM...SPRINGER
LONG TERM...TAYLOR
AVIATION...SPRINGER
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
704 AM CDT SUN MAR 17 2013
.AVIATION...
12Z TAFS FOR KOMA...KLNK...KOFK.
VARIABLE MVFR/VFR CIGS THE PRIMARY CONCERN THIS MORNING THEN
DETERIORATING CONDITIONS LATER THIS AFTERNOON AND THIS EVENING.
A WEATHER SYSTEM IS MOVING ACROSS THE PLAINS THIS MORNING...WITH
THE PRIMARY FOCUS FOR PRECIPITATION ACROSS KANSAS AND MISSOURI.
PERIODS OF MVFR CIGS ARE POSSIBLE THROUGH THE MORNING WITH A
WEAKENING AREA OF LIGHT SNOW AND FLURRIES OVER NORTHEAST NEBRASKA.
LATER THIS AFTERNOON ANOTHER STRONGER WEATHER SYSTEM WILL MOVE
ACROSS THE NORTHERN AND CENTRAL PLAINS. THE RAIN COULD HOLD OFF TO
THE WEST BEFORE 00Z...HOWEVER OVERSPREAD THE TAF SITES TONIGHT
BETWEEN 00-06Z WITH RAIN CHANGING TO SNOW...MOVING OUT AFTER 06Z.
CIGS WILL MAINLY BE VFR...HOWEVER MVFR AND LOCAL IFR CONDITIONS
SHOULD EXPAND ACROSS THE TAF SITE THIS EVENING AS PRECIPITATION
DEVELOPS.
EAST WINDS WILL BECOME SOUTHEAST AND INCREASE TO 10 TO 16KTS WITH
SOME HIGHER GUSTS. THE COLD FRONT WILL BEGIN TO SWING THE WINDS
AROUND TO THE NORTHWEST AT KOFK AROUND 07-09Z. STRONG NORTHWEST
WINDS WILL DEVELOP AT ALL SITES LATER MONDAY.
ZAPOTOCNY
&&
.PREV DISCUSSION... /ISSUED 328 AM CDT SUN MAR 17 2013/
DISCUSSION...
THE CHANCE FOR RAIN AND SNOW TONIGHT THEN WINDS BEHIND COLD FRONT
MONDAY ARE THE PRIMARY FORECAST CONCERNS.
A COUPLE OF AREAS OF PRECIPITATION WERE IN OR NEAR OUR CWA THIS
MORNING. LIGHT SNOW MOVED FROM NORTH CENTRAL INTO NORTHEAST NEBRASKA
DURING THE LATE EVENING...DROPPING A DUSTING TO A HALF INCH OF SNOW
FOR SOME OF OUR NORTHERN AREAS. THIS SEEMED TO BE TIED TO 90-120KT
300MB JET STRETCHING FROM NORTHERN NEBRASKA INTO THE GREAT LAKES.
WITH THAT JET SHIFTING EAST THIS MORNING...THINK ANY LINGERING SNOW
SHOWERS WILL BE SHORT-LIVED AFTER SUNRISE. SHORT RANGE MODELS RAP
AND HRRR CONCUR. THE SECOND AREA OF PRECIPITATION WAS STAYING MOSTLY
SOUTH OF THE CWA ACROSS NORTHERN KANSAS...AND LOOKED TO BE CAUSED BY
MID LEVEL WARM ADVECTION AHEAD OF 700MB SHORTWAVE MIGRATING EAST
THROUGH KANSAS. A FEW RADAR RETURNS MOVED ACROSS THE SOUTHEAST
NEBRASKA BORDER...BUT TRENDS HAVE BEEN TO CONCENTRATE PRECIP JUST
SOUTH OF OUR AREA. SO ONLY SMALL CHANCES EARLY TODAY THERE...WITH
LIGHT SNOW THE MAIN PRECIP TYPE.
ATTENTION THEN TURNS TO STRONG MID LEVEL SHORTWAVE NOW DIVING
THROUGH WASHINGTON AND OREGON INTO IDAHO. THIS FEATURE WILL RACE
EAST AND STRENGTHEN TODAY...REACHING THE WESTERN DAKOTAS BY
00Z...WITH AXIS OF MID LEVEL TROUGH SWINGING THROUGH OUR AREA MONDAY
MORNING. STRONG SURFACE LOW WILL DEVELOP IN THE NORTHERN HIGH PLAINS
THROUGH THE DAY...THEN ROTATE THROUGH THE DAKOTAS OVERNIGHT WHILE
DRIVING A COLD FRONT THROUGH NEBRASKA AND WESTERN IOWA BY SUNRISE
MONDAY. SOUTHEAST TO SOUTH LOW LEVEL FLOW WILL DEVELOP IN OUR AREA
TODAY IN RESPONSE TO LOWERING PRESSURES TO OUR NORTHWEST...AND WILL
PUSH TEMPERATURES TOWARD 40 THIS AFTERNOON. MID LEVEL THETA-E
INCREASE IN DIFFLUENT FLOW REGIME AHEAD OF TROUGH WILL PROVIDE
SUFFICIENT MOISTURE/LIFT FOR PRECIPITATION AS EARLY AS THIS
AFTERNOON IN CENTRAL AND PERHAPS NORTHEAST NEBRASKA. BUT BETTER
CHANCES COME OVERNIGHT AHEAD OF SURFACE COLD FRONT UNDER CORE OF MID
LEVEL JET SEGMENT. HAVE KEPT PRECIPITATION CHANCES RELATIVELY
HIGH...WITH BEST CHANCES ACROSS THE NORTH NEARER BETTER COMBINATION
OF LIFT/MOISTURE.
PRECIPITATION TYPE CONTINUES TO BE AN ISSUE AS SURFACE LAYER REMAINS
ABOVE FREEZING UNTIL COLD FRONT ARRIVES. MODEL DEPICTIONS OF LAYER
TEMPERATURE PROFILES ARE NOT CONSISTENT WITH EACH OTHER...AND
TEMPERATURE TRENDS WITHIN THE SAME MODEL SPORADICALLY MOVE THERMAL
PROFILE FROM JUST ABOVE TO JUST BELOW FREEZING AND BACK AGAIN WITH
TIME. THIS IS LIKELY DUE TO DYNAMIC COOLING EFFECTS GIVEN VIGOROUS
BUT SMALL AREAS OF LIFT UNDER FAST FLOW. SO A VARIETY OF WEATHER
TYPES ARE POSSIBLE FROM TIME TO TIME OVERNIGHT...BUT WILL FOCUS THIS
FORECAST ON TIMING OF PREDOMINANT WEATHER TYPE CHANGING FROM MAINLY
RAIN TO MAINLY SNOW...AND LET POTENTIAL SNOW AMOUNTS FALL OUT OF
THAT THINKING.
THERMAL PROFILES WILL SUPPORT RAIN FROM LATE THIS AFTERNOON THROUGH
MID EVENING...WITH THICKNESS PROGS SUGGESTING A TRANSITION TOWARD
SNOW IN OUR NORTHWEST BY 03Z. THAT TREND WILL QUICKLY SWING EAST AND
SOUTHEAST THROUGH 06Z...WITH MAINLY SNOW EXPECTED IN OUR SOUTH AFTER
09Z. BETTER COOLING REGIME IS EXPECTED ACROSS OUR NORTH...SO HIGHER
POTENTIAL SNOW TOTALS THERE. HOWEVER...STRONG LIFT NEAR AND
NORTH/NORTHEAST OF THE OMAHA METRO AREA AROUND 06Z MAY END UP BEING
THE MAIN SNOW ZONE WITH THIS SYSTEM. AN ENSEMBLE APPROACH TO SNOW
AMOUNT FORECAST SUGGESTS 1 TO 2 INCHES WILL BE COMMON FROM NORTHEAST
NEBRASKA INTO WEST CENTRAL IOWA. THIS COMBINES STRAIGHT MODEL
OUTPUT...COBB CALCULATIONS OF SEVERAL MODELS...AND A GARCIA
MANIPULATION OF MIXING RATIOS TAKING INTO ACCOUNT 6 HOUR PERIOD OF
PRECIPITATION AND A TRANSITION FROM RAIN TO SNOW OCCURRING NEAR THE
MIDWAY POINT OF THE PRECIP.
FAST-MOVING SYSTEM SHOULD TAKE MOST PRECIPITATION EAST OF OUR WESTERN
IOWA COUNTIES BY 12Z MONDAY. STRONG WINDS WILL FOLLOW DURING THE DAY
AS UNIDIRECTIONAL NORTHWEST FLOW AND STRONG COLD ADVECTION POINT TO
EFFECTIVE TRANSFER OF MOMENTUM IN THE BOUNDARY LAYER. FORECAST
SOUNDINGS STILL SHOW THE POTENTIAL FOR 40MPH WIND GUSTS ON MONDAY.
AND AM NOT EXPECTING A LOT OF WARMING MONDAY GIVEN COLD ADVECTION
DESPITE CLEARING SKIES. HAVE HIGHS GENERALLY IN THE 30S NORTH TO
LOWER 40S SOUTH.
THE REST OF THE WEEK STILL LOOKS TO BE COOL. TUESDAY MAY BE THE
WARMEST...OR LEAST COOL...DAY OF THE WEEK WHERE A RELATIVELY MILD
START AND SUNSHINE ALLOW TEMPS TO REBOUND INTO 40S. OTHERWISE
NORTHWEST MID LEVEL FLOW AT MID WEEK WILL BE REPLACED BY WAVE/LOW
APPROACHING FOR THE END OF THE WEEK INTO THE WEEKEND. OFF-AND-ON
PRECIPITATION CHANCES WILL RESULT BEGINNING WEDNESDAY NIGHT...WITH
CLOUDS AND LITTLE IN THE WAY OF WARM/COLD ADVECTION SUGGESTING
TEMPERATURES WILL BE RANGE-BOUND IN THE 20S FOR LOWS AND 30S OR
LOWER 40S FOR HIGHS.
DERGAN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
152 AM EDT SUN MAR 17 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD INTO THE AREA OVERNIGHT BRINGING DRIER
AIR AND SO ONLY PATCHY FLURRIES. THE NEXT WEATHER MAKER FOR THE
AREA WILL BE A COMPLEX LOW PRESSURE SYSTEM OVER THE GREAT LAKES
AND MID ATLANTIC COAST MONDAY AND TUESDAY. THIS SYSTEM WILL BRING
SNOW OR MIXED PRECIPITATION TO THE AREA BEGINNING LATE MONDAY AND
CONTINUING INTO TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
1008 PM UPDATE...
LAST FLURRIES ARE TAPERING OFF ON SCHEDULE, AND IR SAT SHOWS THE
FORECAST CLEARING IS BEGINNING FROM NORTHWEST TO SOUTHEAST. HAVE
MADE SOME MINOR ADJUSTMENTS TO THE TEMPERATURE GRIDS, TIMING THE
FALL OFF COINCIDENT WITH THE RAPID CLEARING. EXISTING FORECAST
REMAINS IN VERY GOOD SHAPE.
610 PM UPDATE...
LIGHT SNOW SHOWERS ARE PROVING TO BE STUBBORN HEADING INTO THE
EVENING HOURS. AFTER CHECKING THE LATEST RAP FIELDS, DECIDED TO
KEEP CHC POPS AROUND FOR A FEW EXTRA HOURS THIS EVENING. GRIDS
LOOK TO BE IN GOOD SHAPE, SO JUST A MINOR UPDATE.
3 PM UPDATE...
BACK EDGE OF THE LGT SNOW MVG RAPIDLY ACROSS CNTRL PA ATTM
AND WILL BRING AN END TO THE SNOW QUICKLY THIS AFTN. HWVR...CRNTS
UPSTREAM SHOW PLENTY OF CLDS AND LL MOISTURE HANGING BACK ALONG
THE FNTL BNDRY. SO...DONT XPCT RAPID CLRG THIS EVE...AND A FEW LGT
FLURRIES COULD LINGER THRU THE NGT. FB RPTS HAVE BEEN ANYWHERE
FROM A TRACE TO TWO INCHES SO FAR...SO WITH THE BACK EDGE MVVG
RAPIDLY EAST...REALLY NO NEED FOR ANY FLAGS WITH THIS EVENT. TEMPS
THIS EVE WILL DROP INTO THE MID TEENS OR LWR IN MANY PLACES WITH
CAA BHD THE LOW. MODEL GUID IN GOOD AGREEMENT ON MINS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
SCNDRY TROF/COLD FNT PASSES EARLY SUN MRNG AND MAY BRING SOME LGT
SNOW SHWRS TO THE NRN ZONES. MUCH DRIER AIR BHD THIS TROF SHD
ALLOW FOR GRADUAL CLRG SUN AFTN...WITH LIMITED LAKE CLDS AND
FLURRIES DUE TO THE VERY DRY AIR AND WEAK INSTABILITY OFF THE COLD
LAKE.
1028MB HIGH SLIDES SLOWLY EAST INTO NEW ENG BY EARLY MON. THIS
WILL PROVIDE THE COLD AIR AND BAROCLINIC ZONE THAT HELP DEEPENTHE
SCNDRY LOW THAT DVLPS LATE MON. OLD LOW MVES WELL WEST INTO THE
WRN LAKES...BUT WITH THIS BLOCKING HI...COLD AIR WILL BE SLOW TO
LEAVE AND WILL BE REENFORCED BY THE DVLPG CSTL LOW. THIS WILL
ALLOW SNOW TO BRK OUT FROM WEST TO EAST LATE MON AND CONT INTO
EARLY TUE. INITIAL BURST OF WAA SNOW COULD BE MODERATELY HEAVY MON
EVE. NAM HAS NOW MVD INTO THE EURO/S CAMP AND KEEPS THE AREA
COLDER THRU THE EVENT. MODEL FCST PROFILES GNRLY SUPPORT ALL SNOW
NORTH OF THE NY/PA BRDR AND EAST OF I81. TO THE SOUTH AND
WEST...WRM LAYR SHD ALLOW A CHG TO FRZG RAIN...WITH THE COLD AIR
DAMMING...DOES NOT LOOK LIKE TEMOPS WILL GET ABC FRZG...EVEN OVER
NE PA...THRU 12Z TUE.
LOW WILL MVE RAPIDLY EAST SO THE CHANCE FOR WRAP ARND SNOW FROM
THE CSTL TUE WILL BE LIMITED. ATTM...SNOWFALL AND ANY ICE AMTS
LOOK TO BE PRETTY SOLIDLY IN THE ADVISORY CATEGORY WO WILL NOT BE
ISSUING ANY FLAGS AND JUST CONT THE MENTION IN THE HWO.
GNRLY FLWD THE COLDER NAM GUID FOR THE GRIDS AS THE GFS BASED MAV
SEEMED TOO WARM.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
2 PM SAT UPDATE...
FOLLOWED WPC GUIDANCE. COLDER THAN NORMAL WITH MORE SNOW SHOWERS.
MODELS ARE SIMILAR. A NOREASTER MOVES NE INTO EASTERN NEW ENGLAND
TUESDAY NIGHT BUT A LARGE UPPER LEVEL LOW REMAINS OVER THE
NORTHEAST US AT LEAST THROUGH FRIDAY. THIS TROF KEEPS THE BIG
STORMS TO THE S0UTH BUT WILL KEEP COLD AIR OVER THE AREA. IT WILL
BE COLD ENOUGH FOR LAKE ENHANCEMENT. SLOW WARMING LATE IN THE
WEEK.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
HIGH PRESSURE CONTINUES TO BUILD IN AND WILL BE IN CHARGE FOR THE
TAF PERIOD...WITH MAINLY VFR. THE EXCEPTION WILL BE THAT A WEAK
UPPER WAVE WILL PASS THROUGH DURING THE MORNING...WHICH ALONG WITH
COLD ENOUGH ATMOSPHERE TO YIELD SOME LAKE CLOUDS/LIGHT
FLURRIES...WILL PRODUCE SOME MVFR RESTRICTIONS WITHIN THE 08Z-17Z
WINDOW. SEE TAFS FOR SPECIFICS ON TIMING. AFTER 17Z ENOUGH DRY AIR
TO AT LEAST LIFT CIGS OUT OF MVFR AND EVEN SCATTER THEM OUT WITH
TIME. LIGHT FLOW AT OR BELOW 10 KTS WILL VEER FROM WNW TO NNW
TODAY...TO LIGHT NNE OR VRB THIS EVENING.
.OUTLOOK...
LATE SUN NIGHT THROUGH MON MRNG...MAINLY VFR.
MIDDAY MON TO TUE PM...DEVELOPING IFR RESTRICTIONS LIKELY IN SNOW
MON PM...TRANSITION TO MIXED PRECIP LATE MON NGT/TUE.
TUE NGT TO THU...MVFR/BRIEF IFR IN SCT SNOW SHWRS...MOSTLY IN NY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DGM
NEAR TERM...DGM/DJP
SHORT TERM...DGM
LONG TERM...TAC
AVIATION...MDP
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
958 AM EDT SUN MAR 17 2013
.SYNOPSIS...
PRECIPITATION WILL SLOWLY OVER RUN A STALLED FRONTAL BOUNDARY IN
THE TENNESSEE VALLEY TODAY...AFFECTING SOUTHERN OHIO AND NORTHERN
KENTUCKY. AS A WAVE OF LOW PRESSURE EJECTS NORTHEAST FROM THE
SOUTHERN PLAINS INTO THE GREAT LAKES THE FRONT WILL ADVANCE SLOWLY
NORTHWARD TONIGHT AND MONDAY. THIS WILL INCREASE PRECIPITATION
CHANCES. SOME PLACES MAY SEE A PERIOD OF WINTRY MIX TODAY AND
TONIGHT PRIOR TO CHANGING TO RAIN AS WARMER AIR MOVES INTO THE
REGION. A FEW THUNDERSTORMS WILL BE POSSIBLE ALONG WITH A
SIGNIFICANT RAIN EVENT BEFORE AN ASSOCIATED COLD FRONT FINALLY
MOVES EAST OF THE REGION MONDAY NIGHT. CHILLY HIGH PRESSURE WILL
FOLLOW.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED TO DROP SOME OF THE NORTHERN TIER OF COUNTIES FROM
ADVISORY.
PREV DISCUSSION:
BAND OF HEAVIER PCPN HAS SET UP ALONG THE OHIO RIVER OVER AND ON
INTO FAR SOUTH CENTRAL OHIO. PCPN HAS GENERALLY SWITCHED OVER TO
ALL SNOW ACROSS OUR AREA. WE ARE STARTING TO GET SOME LIGHT
ACCUMULATIONS PRIMARILY ON GRASSY/EXPOSED SURFACES ACROSS NORTHERN
KENTUCKY AND HAVE EVEN AD A REPORT OF 1 INCH IN ROBERSON COUNTY.
THE NORTHERN EXTENT OF THE PCPN IS THE BIGGEST CONCERN AT THIS
POINT AS OUR NORTHERN TIER OF ADVISORY COUNTIES APPEAR TO BE ON
THE NORTHERN FRINGE. HOWEVER...THE LAST FEW RUNS OF THE RAP ARE
TRYING TO BRING AN ENHANCED BAND OF PCPN UP ACROSS THOSE COUNTIES
THROUGH LATE MORNING AND WE MAY BE BEGINNING TO SEE THAT FORMING
NOW ON RADAR OVER EAST CENTRAL INDIANA. AS A RESULT...WILL LIKELY
SIT TIGHT ON THE ADVISORY AT THE MOMENT AND SEE HOW THINGS DEVELOP
OVER THE NEXT HOUR OR SO...BUT IF THIS FAILS TO MATERIALIZE WILL
PROBABLY NEED TO TRIM BACK SOME OF THE NORTHERN COUNTIES FROM THE
ADVISORY. ELSEWHERE...SOME 1 TO LOCALLY 2 INCH ACCUMULATIONS WILL
BE POSSIBLE ON EXPOSED AND GRASSY SURFACES BUT IMPACT WISE...DO
NOT EXPECT MUCH OF AN ISSUE AS ROAD TEMPERATURES ARE STILL RUNNING
WELL INTO THE 40S ACROSS THE ADVISORY AREA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
UPPER LEVEL FLOW BACKS TONIGHT AHD OF TROF MOVING INTO THE
PLAINS. SFC LOW PRES TO EJECT NE INTO THE LOWER OH VLY BY 12Z
MONDAY. FAVORABLE ISENTROPIC LIFT ASSOCIATED WITH STRENGTHENING 50
KT LLJ ALLOWS PCPN TO OVERSPREAD THE ENTIRE FA. BEST LIFT COMES
INTO PLAY BETWEEN 06Z AND 12Z. AS THIS PRECIP ENCOUNTERS COLDER
AIR A WINTRY MIX WILL SPREAD NORTH TO SOUTH. UNDER THE INFLUENCE
OF WAA THE WINTRY MIX WILL BE LIMITED WITH A CHANGE OVER TO ALL
RAIN MONDAY MORNING. EXPECT LOWS TO RANGE FROM THE LOWER 30S NW TO
THE MID 30S SOUTH.
SFC WAVE TO TO LIFT NE FROM THE LWR OHIO VALLEY INTO THE SRN GREAT
LAKES WITH ASSOCIATED COLD FRONT SWEEPING EAST THRU ILN/S FA BY
MONDAY EVENING. FAVORABLE MOISTURE TRANSPORT WILL EXIST WITH PW/S
INCREASING TO ABOVE 1 INCH ACRS THE SOUTH. THESE VALUES ARE ABOUT
200 PERCENT OF NORMAL. THE SE HALF OF THE FA GETS INTO THE WARM
SECTOR WITH FAVORABLE INSTBY INDICATED WILL MENTION A CHC OF
THUNDER WITH MODERATE RAIN. THIS RAINFALL CUD LEAD TO LOCALIZED
FLOODING THREAT...ESPECIALLY IN THE LICKING...LITTLE MIAMI...OHIO
BRUSH CREEK AND LOWER SCIOTO BASINS. THERE WILL BE A GOOD
TEMPERATURE GRADIENT WITH MONDAYS HIGHS RANGING FROM THE MID 40S
NW TO NEAR 60 SE.
UPPER TROF TO SETTLE INTO SETTLE THE NRN GREAT LAKES WITH NW FLO
DEVELOPING ACRS THE OHIO VLY. SYSTEM IS PROGRESSIVE WITH COLD
FRONT SWEEPING TO THE EAST. HAVE ENDED PCPN A LTL QUICKER WITH A
CHANGE OVER TO SNOW PRIOR TO ENDING LATE MONDAY NIGHT. THIS
QUICKER ENDING WILL LIMIT ANY PSBL ACCUMULATION. LOWS WILL RANGE
FROM THE LOWER 20S NW TO THE LOWER 30S SE. COLD HIGH PRESSURE TO
NOSE IN ON TUESDAY. HIGHS TUESDAY WILL BE 10 TO 12 DEGREES BELOW
NORMAL...RANGING FROM THE MID/UPR 30S NORTH TO THE MID 40S SOUTH.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THERE ARE SOME INDICATIONS THAT A SHORT WAVE DROPPING ACROSS THE
REGION ON WEDNESDAY COULD PRODUCE SOME LIGHT PRECIPITATION. BUT
UNCERTAINTIES IN TIMING...PLACEMENT AND STRENGTH PRECLUDE POPS
ABOVE THRESHOLD AT THIS TIME. OTHERWISE THE LONG TERM PERIOD WILL
BE DRY WITH PERSISTENT BELOW NORMAL TEMPERATURES. RIDGING AT THE
SURFACE WITH UPPER LEVEL NORTHWEST FLOW WILL PREDOMINATE.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
MODEL UNCERTAINTY AND BORDERLINE TEMPERATURES CONTRIBUTE TO A LACK
OF CONFIDENCE IN THIS FORECAST. A BAND OF PRECIPITATION ALONG A
SLOW MOVING FRONTAL BOUNDARY WILL AFFECT SOUTHERN TAF SITES CVG
LUK AND TO A LESSER EXTENT ILN. SNOW MIXING WITH RAIN IS EXPECTED
TO DEVELOP THERE WITH VISIBILITIES FALLING AS LOW AS IFR AT CVG
AND LUK. MAIN EFFECTS SHOULD OCCUR LATE MORNING THROUGH EARLY
AFTERNOON. DAY CMH AND LCK WILL CONTINUE TO HAVE MVFR CEILINGS BUT
PROBABLY NO PRECIP THROUGH THIS AFTERNOON.
MODERATE RAIN WILL OVERSPREAD ALL SITES TONIGHT AS A WAVE OF LOW
PRESSURE TRAVELING ALONG THE FRONT BRINGS WARMER TEMPERATURES AND
A WIDE AREA OF PRECIPITATION. WINDS WILL SHIFT FROM NORTH TO EAST
WITH GUSTS TO 20 KNOTS POSSIBLE AT SOUTHERN SITES LATE IN THE
PERIOD. FOR CVG ON MONDAY...RAIN IS EXPECTED TO END MID
MORNING...WITH WINDS SHIFTING TO SOUTHWEST.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES ARE LIKELY MONDAY
INTO TUESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER WEATHER ADVISORY UNTIL 7 PM EDT THIS EVENING FOR OHZ078-
079-081-082-088.
KY...WINTER WEATHER ADVISORY UNTIL 7 PM EDT THIS EVENING FOR
KYZ089>100.
IN...WINTER WEATHER ADVISORY UNTIL 7 PM EDT THIS EVENING FOR INZ075-
080.
&&
$$
SYNOPSIS...AR
NEAR TERM...JGL
SHORT TERM...AR
LONG TERM...
AVIATION...CONIGLIO
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
906 AM EDT SUN MAR 17 2013
.SYNOPSIS...
PRECIPITATION WILL SLOWLY OVER RUN A STALLED FRONTAL BOUNDARY IN
THE TENNESSEE VALLEY TODAY...AFFECTING SOUTHERN OHIO AND NORTHERN
KENTUCKY. AS A WAVE OF LOW PRESSURE EJECTS NORTHEAST FROM THE
SOUTHERN PLAINS INTO THE GREAT LAKES THE FRONT WILL ADVANCE SLOWLY
NORTHWARD TONIGHT AND MONDAY. THIS WILL INCREASE PRECIPITATION
CHANCES. SOME PLACES MAY SEE A PERIOD OF WINTRY MIX TODAY AND
TONIGHT PRIOR TO CHANGING TO RAIN AS WARMER AIR MOVES INTO THE
REGION. A FEW THUNDERSTORMS WILL BE POSSIBLE ALONG WITH A
SIGNIFICANT RAIN EVENT BEFORE AN ASSOCIATED COLD FRONT FINALLY
MOVES EAST OF THE REGION MONDAY NIGHT. CHILLY HIGH PRESSURE WILL
FOLLOW.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
BAND OF HEAVIER PCPN HAS SET UP ALONG THE OHIO RIVER OVER AND ON
INTO FAR SOUTH CENTRAL OHIO. PCPN HAS GENERALLY SWITCHED OVER TO
ALL SNOW ACROSS OUR AREA. WE ARE STARTING TO GET SOME LIGHT
ACCUMULATIONS PRIMARILY ON GRASSY/EXPOSED SURFACES ACROSS NORTHERN
KENTUCKY AND HAVE EVEN AD A REPORT OF 1 INCH IN ROBERSON COUNTY.
THE NORTHERN EXTENT OF THE PCPN IS THE BIGGEST CONCERN AT THIS
POINT AS OUR NORTHERN TIER OF ADVISORY COUNTIES APPEAR TO BE ON
THE NORTHERN FRINGE. HOWEVER...THE LAST FEW RUNS OF THE RAP ARE TRYING
TO BRING AN ENHANCED BAND OF PCPN UP ACROSS THOSE COUNTIES THROUGH
LATE MORNING AND WE MAY BE BEGINNING TO SEE THAT FORMING NOW ON
RADAR OVER EAST CENTRAL INDIANA. AS A RESULT...WILL LIKELY SIT
TIGHT ON THE ADVISORY AT THE MOMENT AND SEE HOW THINGS DEVELOP
OVER THE NEXT HOUR OR SO...BUT IF THIS FAILS TO MATERIALIZE WILL
PROBABLY NEED TO TRIM BACK SOME OF THE NORTHERN COUNTIES FROM THE
ADVISORY. ELSEWHERE...SOME 1 TO LOCALLY 2 INCH ACCUMULATIONS WILL
BE POSSIBLE ON EXPOSED AND GRASSY SURFACES BUT IMPACT WISE...DO
NOT EXPECT MUCH OF AN ISSUE AS ROAD TEMPERATURES ARE STILL RUNNING
WELL INTO THE 40S ACROSS THE ADVISORY AREA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
UPPER LEVEL FLOW BACKS TONIGHT AHD OF TROF MOVING INTO THE
PLAINS. SFC LOW PRES TO EJECT NE INTO THE LOWER OH VLY BY 12Z
MONDAY. FAVORABLE ISENTROPIC LIFT ASSOCIATED WITH STRENGTHENING 50
KT LLJ ALLOWS PCPN TO OVERSPREAD THE ENTIRE FA. BEST LIFT COMES
INTO PLAY BETWEEN 06Z AND 12Z. AS THIS PRECIP ENCOUNTERS COLDER
AIR A WINTRY MIX WILL SPREAD NORTH TO SOUTH. UNDER THE INFLUENCE
OF WAA THE WINTRY MIX WILL BE LIMITED WITH A CHANGE OVER TO ALL
RAIN MONDAY MORNING. EXPECT LOWS TO RANGE FROM THE LOWER 30S NW TO
THE MID 30S SOUTH.
SFC WAVE TO TO LIFT NE FROM THE LWR OHIO VALLEY INTO THE SRN GREAT
LAKES WITH ASSOCIATED COLD FRONT SWEEPING EAST THRU ILN/S FA BY
MONDAY EVENING. FAVORABLE MOISTURE TRANSPORT WILL EXIST WITH PW/S
INCREASING TO ABOVE 1 INCH ACRS THE SOUTH. THESE VALUES ARE ABOUT
200 PERCENT OF NORMAL. THE SE HALF OF THE FA GETS INTO THE WARM
SECTOR WITH FAVORABLE INSTBY INDICATED WILL MENTION A CHC OF
THUNDER WITH MODERATE RAIN. THIS RAINFALL CUD LEAD TO LOCALIZED
FLOODING THREAT...ESPECIALLY IN THE LICKING...LITTLE MIAMI...OHIO
BRUSH CREEK AND LOWER SCIOTO BASINS. THERE WILL BE A GOOD
TEMPERATURE GRADIENT WITH MONDAYS HIGHS RANGING FROM THE MID 40S
NW TO NEAR 60 SE.
UPPER TROF TO SETTLE INTO SETTLE THE NRN GREAT LAKES WITH NW FLO
DEVELOPING ACRS THE OHIO VLY. SYSTEM IS PROGRESSIVE WITH COLD
FRONT SWEEPING TO THE EAST. HAVE ENDED PCPN A LTL QUICKER WITH A
CHANGE OVER TO SNOW PRIOR TO ENDING LATE MONDAY NIGHT. THIS
QUICKER ENDING WILL LIMIT ANY PSBL ACCUMULATION. LOWS WILL RANGE
FROM THE LOWER 20S NW TO THE LOWER 30S SE. COLD HIGH PRESSURE TO
NOSE IN ON TUESDAY. HIGHS TUESDAY WILL BE 10 TO 12 DEGREES BELOW
NORMAL...RANGING FROM THE MID/UPR 30S NORTH TO THE MID 40S SOUTH.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THERE ARE SOME INDICATIONS THAT A SHORT WAVE DROPPING ACROSS THE
REGION ON WEDNESDAY COULD PRODUCE SOME LIGHT PRECIPITATION. BUT
UNCERTAINTIES IN TIMING...PLACEMENT AND STRENGTH PRECLUDE POPS
ABOVE THRESHOLD AT THIS TIME. OTHERWISE THE LONG TERM PERIOD WILL
BE DRY WITH PERSISTENT BELOW NORMAL TEMPERATURES. RIDGING AT THE
SURFACE WITH UPPER LEVEL NORTHWEST FLOW WILL PREDOMINATE.
&&
.AVIATION /13Z SUNDAY THROUGH THURSDAY/...
MODEL UNCERTAINTY AND BORDERLINE TEMPERATURES CONTRIBUTE TO A LACK
OF CONFIDENCE IN THIS FORECAST. A BAND OF PRECIPITATION ALONG A
SLOW MOVING FRONTAL BOUNDARY WILL AFFECT SOUTHERN TAF SITES CVG
LUK AND TO A LESSER EXTENT ILN. SNOW MIXING WITH RAIN IS EXPECTED
TO DEVELOP THERE WITH VISIBILITIES FALLING AS LOW AS IFR AT CVG
AND LUK. MAIN EFFECTS SHOULD OCCUR LATE MORNING THROUGH EARLY
AFTERNOON. DAY CMH AND LCK WILL CONTINUE TO HAVE MVFR CEILINGS BUT
PROBABLY NO PRECIP THROUGH THIS AFTERNOON.
MODERATE RAIN WILL OVERSPREAD ALL SITES TONIGHT AS A WAVE OF LOW
PRESSURE TRAVELING ALONG THE FRONT BRINGS WARMER TEMPERATURES AND
A WIDE AREA OF PRECIPITATION. WINDS WILL SHIFT FROM NORTH TO EAST
WITH GUSTS TO 20 KNOTS POSSIBLE AT SOUTHERN SITES LATE IN THE
PERIOD. FOR CVG ON MONDAY...RAIN IS EXPECTED TO END MID
MORNING...WITH WINDS SHIFTING TO SOUTHWEST.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES ARE LIKELY MONDAY
INTO TUESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER WEATHER ADVISORY UNTIL 7 PM EDT THIS EVENING FOR
OHZ070>072-077>082-088.
KY...WINTER WEATHER ADVISORY UNTIL 7 PM EDT THIS EVENING FOR
KYZ089>100.
IN...WINTER WEATHER ADVISORY UNTIL 7 PM EDT THIS EVENING FOR INZ066-
073>075-080.
&&
$$
SYNOPSIS...AR
NEAR TERM...JGL
SHORT TERM...AR
LONG TERM...
AVIATION...CONIGLIO
AREA FORECAST DISCUSSION
NWS PUEBLO CO
259 PM MDT SUN MAR 17 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 258 PM MDT SUN MAR 17 2013
...STRONG WINDS AND HIGH FIRE DANGER THE MAIN CONCERN FOR THE I-25
CORRIDOR AND ADJACENT PLAINS...
UPPER TROF CURRENTLY MOVING ACROSS THE AREA WITH NICE DRYING ON THE
BACK SIDE MOVING ACROSS THE SOUTHEAST MOUNTAINS. SOUTHWEST WINDS
HAVE BEGUN TO INCREASE ALONG THE I-25 CORRIDOR...WITH THE SOUTHERN
I-25 CORRIDOR SEEING THE STRONGEST GUSTS THUS FAR...WITH I-25 AT
BUTTE CREEK PICKING UP A GUST TO AROUND 54 MPH SHORTLY AFTER 18Z.
THIS WAS ABOUT THE TIME A WAVE OF THUNDERSTORMS MOVED OFF THE
MOUNTAINS IN THAT AREA. THESE THUNDERSTORMS HAVE SINCE PUSHED OFF
INTO THE FAR SOUTHEAST PLAINS...AND WEATHER SPOTTERS IN THE AREA
HAVE REPORTED SOME BRIEF PEA SIZE HAIL WITH THE STRONGER CELLS. SO
FAR...WIND GUSTS HAVE STAYED UNDER 50 MPH. THIS MAY BE DUE TO THE
FACT THAT SURFACE DEW POINTS ARE STILL FAIRLY HIGH...EVEN BEHIND THE
SFC TROF AXIS...AND WITH LESS OF A T/TD SPREAD...ACCELERATION FROM
DOWNDRAFTS HASN/T BEEN STRONG ENOUGH TO GOOSE WIND SPEEDS ABOVE HIGH
WIND CRITERIA. WILL CONTINUE TO MONITOR THOUGH AS THESE CELLS
CONTINUE TO PROGRESS EASTWARD THROUGH THE AFTERNOON.
MEANWHILE...SFC DEW POINTS HAVE BEGUN TO DROP OFF INTO THE TEENS
ALONG THE I-25 CORRIDOR...AND TEMPERATURES HAVE WARMED INTO THE
LOWER TO MID 60S ACROSS THE SOUTHERN I-25 CORRIDOR. STILL WAITING
FOR THE HUMIDITIES TO DROP BELOW 15 PERCENT...THOUGH FCS AND RED
CREEK RAWS ARE AT 16% AS OF 2 PM. LOCAL 4KM WRF STILL SHOWS DEW
POINTS DROPPING INTO THE LOWER TEENS ALONG THE I-25 CORRIDOR BY
22Z...AND SPREADING EASTWARD INTO THE FAR EASTERN COUNTIES BY 00Z.
SINCE LINE OF CONVECTION THUS FAR WASN/T ENOUGH TO GOOSE UP WINDS
ABOVE HIGH WIND CRITERIA...ONE WINDOW HAS CLOSED. HOWEVER...ANOTHER
SHOT FOR SOME SPOTTY HIGH WIND CRITERIA OPENS AGAIN AROUND 00Z AS
STRONGER WINDS ALOFT BEHIND THE FRONT SPREAD INTO THE I-25
CORRIDOR. BOTH WRF...AND HRRR SHOW WIND GUSTS UP TO 40-45 KTS.
LOCAL 4KM WRF HAS TRENDED DOWN WITH THESE GUSTS THOUGH AS COMPARED
TO THE EARLIER 00Z RUN. SO ALTHOUGH I CAN/T ENTIRELY RULE OUT A
SPOTTY HIGH WIND CRITERIA GUST ALONG THE I-25 CORRIDOR THROUGH EARLY
EVENING...IF IT DOES OCCUR...THINK IT WILL BE TOO SPOTTY/BRIEF TO WARRANT
ANY HIGH WIND HIGHLIGHTS. NAM12 MODELS HINT AT A WEAK MTN TOP
STABLE LAYER DEVELOPING BY 03Z...BUT 18Z NAM HAS DONE AWAY WITH THIS
FEATURE. BY 06Z...WINDS QUICKLY ATTAIN QUITE A BIT OF FORWARD
SHEAR...WHICH SHOULD CUT OFF ANY MTN WAVE POTENTIAL. BOTTOM
LINE...PARAMETERS APPEAR TO NOT BE IN PLACE LONG ENOUGH TO JUSTIFY A
HIGH WIND WARNING AT THIS POINT. WITHOUT A CRITICAL LAYER IN
PLACE...A WAVE INDUCED ONE WOULD HAVE TO OCCUR TO BRING STRONG WINDS
DOWN...AND THIS SEEMS LESS AND LESS LIKELY...THOUGH NOT ENTIRELY
IMPOSSIBLE.
MEANWHILE...OROGRAPHIC SNOW SHOWERS WILL CONTINUE ALONG THE
CONTINENTAL DIVIDE...THOUGH SHOULD BE DECREASING RAPIDLY IN COVERAGE
OVERNIGHT. ANOTHER 1 TO 2 INCHES WILL BE POSSIBLE OVERNIGHT WITH
SOME POOR VISIBILITIES AT TIMES IN WIND DRIVEN SNOW. HAVE BEEN
MONITORING WEB CAMS...AND SO FAR VISIBILITY HASN/T BEEN IMPACTED
THAT MUCH TO WARRANT AN ADVISORY. IN FACT...CDOT WEB CAMS OVER WOLF
CREEK AND FREMONT PASSES SHOW THE ROADS HAVE MELTED OUT IN THE PAST
COUPLE HOURS. MOST HAZARDOUS CONDITIONS WILL LIKELY CONTINUE ACROSS
MONARCH PASS WHERE ROAD SFC WILL STAY SNOW COVERED.
FOR TOMORROW...WINDS WILL INCREASE AGAIN ALONG THE I-25 CORRIDOR AND
WITH DEEP DRY AIR OVER THE REGION...SFC DEW POINTS WILL FALL INTO
THE SINGLE DIGITS AND EVEN BELOW ZERO. ALTHOUGH WINDS ARE NOT
EXPECTED TO BE A STRONG AS THEY WERE TODAY...WE COULD BE LOOKING AT
BRIEF CRITICAL FIRE WEATHER CONDITIONS ACROSS
PUEBLO...CROWLEY...OTERO...AND PERHAPS PORTIONS OF LAS ANIMAS COUNTIES
IN THE AFTERNOON. FOR NOW...NOT GETTING A LONG ENOUGH DURATION (3
HRS OR MORE) OF HUMIDITY BELOW 15 PERCENT...SO WILL HOLD OFF ON ANY
FIRE WEATHER HIGHLIGHTS. BUT THIS MAY NEED TO BE REVISITED WITH
FUTURE MODEL RUNS. TEMPERATURES SHOULD BE A LITTLE COOLER
TOMORROW...BUT WITH THE WIND THEY SHOULD STILL WARM INTO THE 50S
ACROSS THE PLAINS...WITH 30S AND 40S ACROSS THE HIGH COUNTRY. -KT
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 258 PM MDT SUN MAR 17 2013
...COOLER AND MORE UNSETTLED WEATHER FOR MID WEEK AND BEYOND...
MONDAY NIGHT-TUESDAY NIGHT...MODERATING WESTERLY FLOW PROGGED
ACROSS THE REGION WITH FLAT RIDGING BUILDING ACROSS THE GREAT BASIN
AND INTO THE ROCKIES. WILL CONTINUE TO SEE SOME LIGHT SNOW SHOWERS
ACROSS THE CENTRAL MTS MONDAY EVENING WITH SHOWERS ENDING THROUGH
THE LATE EVENING AND OVERNIGHT HOURS WITH DEVELOPING WAA. WITH THE
DECREASING FLOW ALOFT AND DECOUPLED WINDS ACROSS THE PLAINS...HAVE
LOWERED OVERNIGHT LOWS A TAD...ESPECIALLY ACROSS VALLEY LOCALES.
SOME MODEL DIFFERENCES CONTINUE TO BE INDICATED FOR TUESDAY
AFTERNOON AND EVENING AS THE LATEST ECMWF CONTINUES TO INDICATE
STRONGER SOUTHERN STREAM ENERGY TRANSLATING ACROSS THE DESERT SW
AND NORTHERN NEW MEXICO AND PRINTS OUT SOME LIGHT QFP ACROSS THE
SOUTHERN MTS TUESDAY AFTERNOON AND EVENING. THE GFS IS A LITTLE
FURTHER SOUTH WITH THIS SYSTEM AND ITS ASSOCIATED QPF. AT ANY
RATE...HAVE FOLLOWED CLOSER TO THE GFS SOLUTION WITH LATEST WPC
(FORMERLY HPC) GUIDANCE TRENDING AWAY FROM A DISTINCT SOUTHERN
STREAM SHORTWAVE AT THIS TIME...AND HAVE STARTED TO TRIM BACK THE
SLIGHT POPS ACROSS THE HIGHER TERRAIN OF THE CONTDVD FOR TUESDAY
AFTERNOON AND EVENING. AS FOR TEMPERATURES...WITH WEAK UPSLOPE FLOW
PROGGED ACROSS THE EASTERN PLAINS...HAVE TRIMMED BACK HIGHS A TAD AS
WELL THOUGH SHOULD STILL BE NEAR SEASONAL AVERAGES.
WEDNESDAY-FRIDAY...COOLER AND MORE UNSETTLED WEATHER REMAINS IN THE
OFFING...THOUGH MODELS HAVE TRENDED SLOWER AND FURTHER NORTH WITH
THE BROAD UPPER TROUGH CARVING OUT ACROSS THE WEST COAST ON
WEDNESDAY WHICH THEN CONTINUES TO TRANSLATE OUT ACROSS THE NORTHERN
GREAT BASIN AND THE NORTHERN ROCKIES THROUGH FRIDAY. THIS FURTHER
NORTH TREND WOULD KEEP THE BULK OF THE PRECIPITATION ACROSS THE
CENTRAL MTS THROUGH NORTHEASTERN COLORADO AND NORTHWESTERN KANSAS
WITH MORE DOWNSLOPE FLOW IN PLACE ACROSS SOUTHEAST COLORADO. AT ANY
RATE...MOISTURE INCREASES ACROSS THE CONTDVD WEDNESDAY WITH SHOWERS
DEVELOPING THROUGH MORNING AND INCREASING IN COVERAGE AND SPREADING
EAST THROUGH THE AFTERNOON AND EVENING. SHOWERS TO CONTINUE ACROSS
THE HIGHER TERRAIN WEDNESDAY NIGHT AND THURSDAY AS BROAD TROUGH
CONTINUES TO MOVE EAST...AND MAY NEED SOME HIGHLIGHTS THROUGH THIS
PERIOD...MAINLY FOR THE CENTRAL MTS. BEST CHANCES OF RAIN AND SNOW
SHOWERS ACROSS THE EASTERN COLORADO LOOKS TO BE THURSDAY AFTERNOON
AND NIGHT AS AN ASSOCIATED COLD FRONT BACKS ACROSS THE PLAINS.
SHOWERS TO PERSIST ACROSS MAINLY THE HIGHER TERRAIN ON FRIDAY WITH
COOL NORTHWEST FLOW AND POSSIBLE TRAILING ENERGY TRANSLATING ACROSS
THE GREAT BASIN. HIGHS ON FRIDAY LOOK TO BE WELL BELOW SEASONAL
LEVELS WITH THE COLD AIRMASS IN PLACE.
SATURDAY-SUNDAY...LOW CONFIDENCE FORECAST CONTINUES INTO THE WEEKEND
AS THE LATEST EC CONTINUES TO INDICATE COOL NORTHWEST FLOW WITH
SEVERAL EMBEDDED SHORTWAVES TRANSLATING THROUGH THE FLOW...WHERE AS
THE GFS HAS SHORT WAVE RIDGING BUILDING ACROSS THE GREAT BASIN AND
INTO THE ROCKIES. WITH THAT SAID...HAVE STAYED WITH MODEL CONSENSUS
WHICH KEEPS ISOLATED POPS ACROSS THE HIGHER TERRAIN ALONG WITH A
SLOW WARMUP TO SEASONAL TEMPERATURES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 258 PM MDT SUN MAR 17 2013
GUSTY WINDS THE MAIN CONCERN IN TAF SITES...WITH WEST TO NORTHWEST
WINDS PICKING UP AND GUSTING TO AROUND 40 KTS AT KCOS AND KPUB
DURING THE LATE AFTERNOON AND EARLY EVENING. KALS COULD SEE GUSTS
TO AROUND 30 KTS. WINDOW FOR VCSH HAS PRIMARILY ENDED FOR THE TAF
SITES...THOUGH THE CENTRAL AND SOUTHWEST MOUNTAINS COULD STILL SEE
SOME MTN OBSCURATIONS THROUGH TONIGHT...ESPECIALLY ACROSS THE
SAWATCH AND MOSQUITO RANGES WHERE OROGRAPHIC SNOW SHOWERS WILL
CONTINUE. WINDS WILL DECREASE AFTER 02Z...THOUGH STILL REMAIN GUSTY
AT TIMES FROM THE NORTHWEST AT 10-25 KTS FOR KCOS AND KPUB. ON
MONDAY...WINDS WILL INCREASE AGAIN AFTER 18Z TO AROUND 15-25 KTS FOR
KCOS AND KPUB. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR COZ227-228-
231>233.
&&
$$
SHORT TERM...KT
LONG TERM...MW
AVIATION...KT
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
512 PM CDT SUN MAR 17 2013
.DISCUSSION...
315 PM CDT
THE FORECAST CHALLENGES REMAIN FIRST ON THE LIKELIHOOD FOR SOME
LIGHT WINTRY PRECIP IN PLACES TONIGHT AND THEN LIGHT SNOW
ACCUMULATIONS ACROSS FAR NORTHERN ILLINOIS ON MONDAY...FOLLOWED BY
WHAT WILL BECOME THE BIG STORY AND THAT IS WELL BELOW NORMAL
TEMPERATURES FROM TUESDAY THROUGH THE END OF THE WORKWEEK.
SYNOPSIS...THE POLAR VORTEX OVER HUDSON BAY DURING MUCH OF LAST
WEEK HAS SHIFTED EAST...TEMPORARILY...ALLOWING FOR A FASTER PACED
DISTURBED FLOW TO HAVE EVOLVED INTO THE MIDDLE OF THE COUNTRY
TODAY. ONE SHORT WAVE IMPULSE OVER THE OZARKS THIS AFTERNOON IS
MOVING NORTHEAST SPREADING A VEIL OF HIGH CLOUDS ACROSS PART OF
THE AREA. THIS WILL BE THE SYSTEM TO BRING LIGHT PRECIP LATER
TONIGHT AS IT CONTINUES ALONG ITS TRACK. FURTHER WEST...A WELL-
DEFINED UPPER LEVEL JET IS MOVING EAST ACROSS THE WESTERN CONUS
AND USHERING A PRONOUNCED UPPER WAVE ACROSS EASTERN WY THIS
AFTERNOON. THIS WILL BE THE MONDAY MORNING INTO EARLY AFTERNOON
PRECIP MAKER AND BRING A POWERFUL COLD FRONT THROUGH MONDAY
EVE. THIS SYSTEM WILL CATCH UP WITH ITS PREDECESSOR ALLOWING
PHASING AND AN OVERALL IMPRESSIVE SYSTEM DEEPENING AND ORGANIZATION
OVER THE GREAT LAKES MONDAY NIGHT INTO TUESDAY. A MASSIVE
ANOMALOUSLY DEEP CLOSED UPPER LOW WILL BE THE RESULT. WITH FURTHER
BLOCKING UPSTREAM OVER THE NORTH ATLANTIC...THIS WILL MOVE LITTLE
THUS SUSTAINING NORTHWEST FLOW OVER THE REGION WITH REGULAR
REINFORCING SHOTS OF REALLY COLD AIR BY MARCH STANDARDS.
TONIGHT...MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON THE SHORT
WAVE OVER MO MOVING NORTHEAST AND BRINGING WITH IT THE ONGOING
WARM MOIST ADVECTION ALOFT THAT HAS PRODUCED PRECIP DOWNSTATE
TODAY. MODEL DIFFERENCES REMAIN IN PRECIP TYPE WHICH CAN BE
EXPECTED WITH HOW CLOSE TO 0C A GOOD PART OF THE FORECAST THERMAL
PROFILES ARE. VARIOUS WRF AND ARW MODELS INDICATE PRECIP SHOULD
SLOWLY SPREAD NORTHWARD THROUGH CENTRAL IL THIS EVE AND FORECAST
ISENTROPIC SURFACES AND ELEVATED MOISTURE CONVERGENCE FROM BOTH
THE RAP AND NAM AGREE WITH THIS DEPICTION. SOME FLURRIES/DRIZZLE
AHEAD OF THE MAIN PRECIP AREA ARE POSSIBLE AS THE ATMOSPHERE
SATURATES.
THERE ARE SEVERAL CULPRITS FOR THE PRECIP TYPE QUESTIONS. FOR
ONE...BECAUSE THE AREA IS GRAZED BY THE LEAD SHORT WAVE AND ITS
DEEPER SATURATION...THERE IS UNCERTAINTY ON WHETHER ICE CRYSTALS
ARE INTRODUCED. SECOND...THERE IS A SEVERAL THOUSAND FT DEEP
LAYER AROUND 0C FORECAST ACROSS A LARGE PART OF THE AREA AS PRECIP
SPREADS IN. AND FINALLY...SURFACE TEMPERATURES ARE LIKELY TO HOLD
STEADY THROUGH LATE EVE AND OVERNIGHT...AND MAY EVEN INCH UP IN
THE FAR SOUTH DEPENDING ON PRECIP STRENGTH...WHICH PRIMARILY LOOKS
LIGHT.
WHILE THERE MAY BE LIGHT SNOW IN THE ONSET SOUTH OF I-80 THIS EVE
AS THE WARM NOSE IS MARGINAL...IT APPEARS THAT BY OVERNIGHT THIS
LAYER WILL BE DEEP ENOUGH TO SUPPORT FULL MELTING. THE MOISTURE
TRANSPORT NOSE FROM THE SHORT WAVE POINTS INTO THE SOUTHEAST
FORECAST AREA...AND DO HAVE AROUND ONE TENTH OF AN INCH OF QPF.
SURFACE TEMPERATURES LOOK TO BE JUST ABOVE FREEZING THERE...BUT
WILL NEED TO BE WATCHED CLOSELY. FURTHER TO THE NORTH...TOWARD
I-80 AND EVEN SOMEWHAT NORTH FROM THERE...QPF LOOKS TO BE LIGHT
OVERNIGHT...BUT PROFILES DO SUPPORT LIGHT FREEZING RAIN OR SLEET
DEPENDING ON WHICH MODEL. THIS DOES INCLUDE FOR DOWNTOWN CHICAGO.
TOWARD FAR NORTHERN IL...THE PROFILES BECOME COOL ENOUGH THAT THE
TYPE SHOULD BE SLEET OR SNOW...BUT AGAIN PRIOR TO DAYBREAK THIS
LOOKS TO BE LIGHT.
AS THE MAIN UPPER WAVE APPROACHES MONDAY MORNING...GUIDANCE
AGREES ON THIS BEING THE STRONGEST PERIOD OF OMEGA/QG FORCING FOR
THE NORTHERN AREA. BECAUSE OF THIS FORCING AND THE ALREADY VERY
MARGINAL PROFILES FOR ANYTHING BUT SNOW THAT FAR NORTH...PRECIP
TYPE LOOKS TO TRANSITION TO A WET SNOW. THE HIGHER RATES SHOULD BE
TO THE NORTH OF THE CWA BUT ENOUGH SUPPORT WITH 31F-33F SURFACE
TEMPERATURES TO SUPPORT UP TO A COUPLE INCHES OF SNOW NEAR THE WI
BORDER. THE BEST TIMING FOR CHICAGO LOOKS TO BE FROM MID TO LATE
MORNING INTO EARLY AFTERNOON...WITH A DUSTING SOUTH TO ONE TO TWO
INCHES IN THE NORTH. STRONG DRYING IN THE MID-LEVELS IS FORECAST
TO FLOOD OVER THE AREA DURING THE AFTERNOON...CUTTING OFF MOST OF
THE FORCING FOR PRECIP. THIS WILL ALLOW TEMPERATURES TO MODERATE
ACROSS MUCH OF THE AREA BEFORE THE INCOMING PLUNGE...AND ITS
POSSIBLE MID 40S ARE REACHED SOUTH OF I-80 DEPENDING ON DEGREE OF
SCATTERING.
BY EARLY MONDAY EVE THE SYSTEMS COLD FRONT WILL BE SWEEPING ACROSS
NORTH CENTRAL IL. THE TEMPERATURE DROP LOOKS TO BE SHARP FOR THE
FIRST COUPLE HOURS AFTER THE FRONT AND HAVE TRIED TO MASSAGE SOME
OF THAT INTO THE HOURLY FORECAST GRIDS GIVEN THE HIGH CONFIDENCE
ALREADY. WITH THE MIXED BOUNDARY LAYER AND STRONG ISALLOBARIC
COMPONENT FORECAST...WINDS LOOK TO BE GUSTING TO 30 AND MAYBE EVEN
40 MPH /ESPECIALLY RIGHT AFTER FROPA/. THE CIPS ANALOG GUIDANCE
DOES HAVE A MAJORITY OF ITS MATCHES FAVORING GUSTS THAT HIGH IN
THE REGION. WIND CHILLS ARE EXPECTED TO FREE FALL INTO THE SINGLE
DIGITS BY MID EVE...AND THEN BELOW ZERO IN NORTHERN AREAS
OVERNIGHT. AS THE UPPER LOW MOVES ACROSS WI...ITS SOUTHERN FLANK
OF MID-LEVEL COLD AIR ADVECTION AND WRAPAROUND LOW-LEVEL MOISTURE
MAY BE ENOUGH TO SUPPORT FLURRIES OR EVEN SHOW SHOWERS. WHILE THIS
WILL BE LIGHT GIVEN LIMITED OVERALL FORCING...WITH THE GUSTY WINDS
AND THE LOWERING WATER CONTENT OF THE SNOW...THERE MAY BE SOME
MARKEDLY REDUCED VISIBILITIES IF AND WHERE SOME OF THIS SNOW
IS ABLE MATERIALIZE ACROSS FAR NORTHERN IL MONDAY EVE.
FOR TUESDAY AND BEYOND...THE COLD AIR ADVECTION CONTINUES TO
REINFORCE ITSELF WITH MULTIPLE COLD FRONTS AND MASSIVE CYCLONIC
FLOW. THIS FLOW WILL KEEP THE POTENTIAL FOR AT LEAST
STRATOCU...ALONG WITH THE CHANCE FOR SNOW SHOWERS.
HOWEVER...TEMPERATURES WERE THE FOCUS...AND THEY LOOK TO BE
REMARKABLY LOW FOR THE LATTER HALF OF MARCH. 850MB TEMPERATURES
ARE FORECAST TO DROP TO AROUND -15C TUE MORNING AND THEN AGAIN WED
MORNING. THE SURFACE WIND COMPONENT REMAINS ELEVATED THROUGH
WED...BUT STILL NIGHTTIME TEMPERATURES WILL FALL INTO THE TEENS
AREA WIDE THANKS TO THE COLD AIR ADVECTION. HIGHS WILL NOT REBOUND
MUCH...AND IN SOME PLACES WILL REMAIN BELOW 30F ON WEDNESDAY. IN
FACT...THE LOW MAXIMUM TEMPERATURE RECORD FOR WED IN ROCKFORD OF
ONLY 22F LOOKS TO BE POTENTIALLY IN JEOPARDY. THE SURFACE
HIGH BUILDS IN LATER THU THROUGH THE EARLY PART OF THE WEEKEND.
WITH THE BLOCKED FLOW...THE COLD AIR MASS HAS NO WHERE TO GO BUT
REINFORCE ITSELF FROM THE NORTH. AND ON THAT NOTE...BACKWARDS
TRAJECTORIES FROM THE GFS FOR WED INDICATE PARCELS ORIGINATING FROM
60 DEGREES NORTH LATITUDE /THE BORDER OF THE NORTHERN AND
SOUTHERN CANADIAN PROVINCES/. ALSO CONSIDERING THE EXTENT OF THE
SNOW COVER TO OUR NORTHWEST...WHICH WILL EXPAND TONIGHT INTO
MONDAY...LITTLE AIR MASS MODIFICATION IS ABLE TO OCCUR.
QUITE FASCINATING FOR LATE MARCH!
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* GUSTY EAST WINDS DIMINISHING FOR A TIME THIS EVENING...THEN
INCREASING FROM THE EAST-SOUTHEAST OVERNIGHT.
* POTENTIAL FOR MIX OF SN/PL INCREASES APPROACHING 12Z MONDAY.
MVFR CIGS EXPECTED...IFR POSSIBLE.
RATZER
//DISCUSSION...UPDATED 18Z...
CEILINGS AT MVFR/VFR LEVELS THAT PUSHED INLAND FROM LAKE MICHIGAN
THIS MORNING WILL BECOME SCATTERED CLOUDS BY LATE THIS AFTERNOON
AS THE LOW LEVEL FLOW TURNS MORE TO THE EAST-SOUTHEAST AND BECOMES
LESS FAVORABLE FOR LAKE EFFECT CLOUDS.
A LOW PRESSURE SYSTEM WILL MOVE FROM THE NORTHERN PLAINS TO LAKE
SUPERIOR THROUGH MONDAY NIGHT. A PUSH OF RELATIVELY WARM AND MOIST
AIR WILL WORK INTO NORTHERN ILLINOIS AND NORTHWEST INDIANA TONIGHT
AHEAD OF THE SYSTEM...AND WILL LEAD TO PRECIPITATION DEVELOPMENT
MONDAY MORNING. START TIME DEPENDS ON WHEN THE LOW LEVELS BECOME
SATURATED AND MAY NEED TO BE ADJUSTED AS DETAILS BECOME CLEARER.
TEMPERATURE FORECASTS SUPPORT MIXED PRECIPITATION WITH A GOOD
CHANCE FOR A PERIOD OF FREEZING RAIN AT THE START. CEILINGS WILL
DROP QUICKLY WHEN PRECIPITATION BEGINS...WITH LOW END MVFR LIKELY
AND IFR POSSIBLE. THE WHOLE SYSTEM WILL MOVE FAIRLY QUICKLY AND
THE PRECIPITATION WILL TAPER OFF BY LATE MONDAY AFTERNOON AND
EVENING.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM-HIGH CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
233 PM CDT
MAIN CONCERN FOR THE MARINE FORECAST WILL BE PERIOD OF GALES
POSSIBLE MONDAY EVENING THROUGH LATE TUESDAY. TODAY...HIGH PRESSURE
IS CENTERED OVER THE GREAT LAKES REGION PROVIDING DIMINISHING
EAST/NORTHEAST FLOW ACROSS LAKE MICHIGAN. TWO AREAS OF LOW PRESSURE
ARE TAKING SHAPE...ONE ACROSS THE NORTHERN ROCKIES AND THE SECOND
OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY. THE NORTHERN LOW
IS EXPECTED TO MOVE EAST INTO MINNESOTA TONIGHT WITH WINDS OVER THE
LAKE BECOMING SOUTHEAST AND INCREASING INTO THE 20 TO 25 KT POSSIBLY
30 KT RANGE. THE GRADIENT AHEAD OF THE LOW THEN QUICKLY DIMINISHES
MONDAY AS THE LOW MOVES INTO WISCONSIN AND BROAD TROUGHING TAKES
PLACES ACROSS LAKE MICHIGAN BETWEEN THE NORTHERN LOW...AND THE
SOUTHERN LOW AS IT MOVES INTO THE SOUTHERN APPALACHIANS. THIS SHOULD
ALLOW WINDS TO DIMINISH FOR A SHORT PERIOD DURING THE DAY MONDAY
BEFORE WINDS TURN SOUTHWEST...THEN WEST AND QUICKLY INCREASE AGAIN
AS THE NORTHERN LOW MOVES EAST OF LAKE MICHIGAN. WITH THE GRADIENT
QUICKLY STRENGTHENS AND STRONG HEIGHT RISES MOVING IN BEHIND THE
DEPARTING LOW...GALES ARE EXPECTED ACROSS PORTIONS OF LAKE MICHIGAN.
CURRENTLY...THE BEST CHANCES FOR GALES APPEAR ACROSS THE SOUTHERN
HALF TO TWO THIRDS OF THE LAKE...WITH THE GRADIENT SLIGHTLY WEAKER
ACROSS FAR NORTHERN LAKE MICHIGAN CLOSER TO THE LOW TRACK. WILL
ISSUE A GALE WATCH FOR THESE AREAS MONDAY EVENING THROUGH TUESDAY
EVENING. WINDS REMAIN ELEVATED AROUND 30 KT THROUGH THE DAY
WEDNESDAY BEFORE GRADUALLY TAPERING LATE IN THE WEEK.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
GALE WATCH...LMZ080-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ872-LMZ874-LMZ876-LMZ878...10 PM MONDAY TO 9 PM
TUESDAY.
GALE WATCH...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
319 PM CDT SUN MAR 17 2013
.DISCUSSION...
315 PM CDT
THE FORECAST CHALLENGES REMAIN FIRST ON THE LIKELIHOOD FOR SOME
LIGHT WINTRY PRECIP IN PLACES TONIGHT AND THEN LIGHT SNOW
ACCUMULATIONS ACROSS FAR NORTHERN ILLINOIS ON MONDAY...FOLLOWED BY
WHAT WILL BECOME THE BIG STORY AND THAT IS WELL BELOW NORMAL
TEMPERATURES FROM TUESDAY THROUGH THE END OF THE WORKWEEK.
SYNOPSIS...THE POLAR VORTEX OVER HUDSON BAY DURING MUCH OF LAST
WEEK HAS SHIFTED EAST...TEMPORARILY...ALLOWING FOR A FASTER PACED
DISTURBED FLOW TO HAVE EVOLVED INTO THE MIDDLE OF THE COUNTRY
TODAY. ONE SHORT WAVE IMPULSE OVER THE OZARKS THIS AFTERNOON IS
MOVING NORTHEAST SPREADING A VEIL OF HIGH CLOUDS ACROSS PART OF
THE AREA. THIS WILL BE THE SYSTEM TO BRING LIGHT PRECIP LATER
TONIGHT AS IT CONTINUES ALONG ITS TRACK. FURTHER WEST...A WELL-
DEFINED UPPER LEVEL JET IS MOVING EAST ACROSS THE WESTERN CONUS
AND USHERING A PRONOUNCED UPPER WAVE ACROSS EASTERN WY THIS
AFTERNOON. THIS WILL BE THE MONDAY MORNING INTO EARLY AFTERNOON
PRECIP MAKER AND BRING A POWERFUL COLD FRONT THROUGH MONDAY
EVE. THIS SYSTEM WILL CATCH UP WITH ITS PREDECESSOR ALLOWING
PHASING AND AN OVERALL IMPRESSIVE SYSTEM DEEPENING AND ORGANIZATION
OVER THE GREAT LAKES MONDAY NIGHT INTO TUESDAY. A MASSIVE
ANOMALOUSLY DEEP CLOSED UPPER LOW WILL BE THE RESULT. WITH FURTHER
BLOCKING UPSTREAM OVER THE NORTH ATLANTIC...THIS WILL MOVE LITTLE
THUS SUSTAINING NORTHWEST FLOW OVER THE REGION WITH REGULAR
REINFORCING SHOTS OF REALLY COLD AIR BY MARCH STANDARDS.
TONIGHT...MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON THE SHORT
WAVE OVER MO MOVING NORTHEAST AND BRINGING WITH IT THE ONGOING
WARM MOIST ADVECTION ALOFT THAT HAS PRODUCED PRECIP DOWNSTATE
TODAY. MODEL DIFFERENCES REMAIN IN PRECIP TYPE WHICH CAN BE
EXPECTED WITH HOW CLOSE TO 0C A GOOD PART OF THE FORECAST THERMAL
PROFILES ARE. VARIOUS WRF AND ARW MODELS INDICATE PRECIP SHOULD
SLOWLY SPREAD NORTHWARD THROUGH CENTRAL IL THIS EVE AND FORECAST
ISENTROPIC SURFACES AND ELEVATED MOISTURE CONVERGENCE FROM BOTH
THE RAP AND NAM AGREE WITH THIS DEPICTION. SOME FLURRIES/DRIZZLE
AHEAD OF THE MAIN PRECIP AREA ARE POSSIBLE AS THE ATMOSPHERE
SATURATES.
THERE ARE SEVERAL CULPRITS FOR THE PRECIP TYPE QUESTIONS. FOR
ONE...BECAUSE THE AREA IS GRAZED BY THE LEAD SHORT WAVE AND ITS
DEEPER SATURATION...THERE IS UNCERTAINTY ON WHETHER ICE CRYSTALS
ARE INTRODUCED. SECOND...THERE IS A SEVERAL THOUSAND FT DEEP
LAYER AROUND 0C FORECAST ACROSS A LARGE PART OF THE AREA AS PRECIP
SPREADS IN. AND FINALLY...SURFACE TEMPERATURES ARE LIKELY TO HOLD
STEADY THROUGH LATE EVE AND OVERNIGHT...AND MAY EVEN INCH UP IN
THE FAR SOUTH DEPENDING ON PRECIP STRENGTH...WHICH PRIMARILY LOOKS
LIGHT.
WHILE THERE MAY BE LIGHT SNOW IN THE ONSET SOUTH OF I-80 THIS EVE
AS THE WARM NOSE IS MARGINAL...IT APPEARS THAT BY OVERNIGHT THIS
LAYER WILL BE DEEP ENOUGH TO SUPPORT FULL MELTING. THE MOISTURE
TRANSPORT NOSE FROM THE SHORT WAVE POINTS INTO THE SOUTHEAST
FORECAST AREA...AND DO HAVE AROUND ONE TENTH OF AN INCH OF QPF.
SURFACE TEMPERATURES LOOK TO BE JUST ABOVE FREEZING THERE...BUT
WILL NEED TO BE WATCHED CLOSELY. FURTHER TO THE NORTH...TOWARD
I-80 AND EVEN SOMEWHAT NORTH FROM THERE...QPF LOOKS TO BE LIGHT
OVERNIGHT...BUT PROFILES DO SUPPORT LIGHT FREEZING RAIN OR SLEET
DEPENDING ON WHICH MODEL. THIS DOES INCLUDE FOR DOWNTOWN CHICAGO.
TOWARD FAR NORTHERN IL...THE PROFILES BECOME COOL ENOUGH THAT THE
TYPE SHOULD BE SLEET OR SNOW...BUT AGAIN PRIOR TO DAYBREAK THIS
LOOKS TO BE LIGHT.
AS THE MAIN UPPER WAVE APPROACHES MONDAY MORNING...GUIDANCE
AGREES ON THIS BEING THE STRONGEST PERIOD OF OMEGA/QG FORCING FOR
THE NORTHERN AREA. BECAUSE OF THIS FORCING AND THE ALREADY VERY
MARGINAL PROFILES FOR ANYTHING BUT SNOW THAT FAR NORTH...PRECIP
TYPE LOOKS TO TRANSITION TO A WET SNOW. THE HIGHER RATES SHOULD BE
TO THE NORTH OF THE CWA BUT ENOUGH SUPPORT WITH 31F-33F SURFACE
TEMPERATURES TO SUPPORT UP TO A COUPLE INCHES OF SNOW NEAR THE WI
BORDER. THE BEST TIMING FOR CHICAGO LOOKS TO BE FROM MID TO LATE
MORNING INTO EARLY AFTERNOON...WITH A DUSTING SOUTH TO ONE TO TWO
INCHES IN THE NORTH. STRONG DRYING IN THE MID-LEVELS IS FORECAST
TO FLOOD OVER THE AREA DURING THE AFTERNOON...CUTTING OFF MOST OF
THE FORCING FOR PRECIP. THIS WILL ALLOW TEMPERATURES TO MODERATE
ACROSS MUCH OF THE AREA BEFORE THE INCOMING PLUNGE...AND ITS
POSSIBLE MID 40S ARE REACHED SOUTH OF I-80 DEPENDING ON DEGREE OF
SCATTERING.
BY EARLY MONDAY EVE THE SYSTEMS COLD FRONT WILL BE SWEEPING ACROSS
NORTH CENTRAL IL. THE TEMPERATURE DROP LOOKS TO BE SHARP FOR THE
FIRST COUPLE HOURS AFTER THE FRONT AND HAVE TRIED TO MASSAGE SOME
OF THAT INTO THE HOURLY FORECAST GRIDS GIVEN THE HIGH CONFIDENCE
ALREADY. WITH THE MIXED BOUNDARY LAYER AND STRONG ISALLOBARIC
COMPONENT FORECAST...WINDS LOOK TO BE GUSTING TO 30 AND MAYBE EVEN
40 MPH /ESPECIALLY RIGHT AFTER FROPA/. THE CIPS ANALOG GUIDANCE
DOES HAVE A MAJORITY OF ITS MATCHES FAVORING GUSTS THAT HIGH IN
THE REGION. WIND CHILLS ARE EXPECTED TO FREE FALL INTO THE SINGLE
DIGITS BY MID EVE...AND THEN BELOW ZERO IN NORTHERN AREAS
OVERNIGHT. AS THE UPPER LOW MOVES ACROSS WI...ITS SOUTHERN FLANK
OF MID-LEVEL COLD AIR ADVECTION AND WRAPAROUND LOW-LEVEL MOISTURE
MAY BE ENOUGH TO SUPPORT FLURRIES OR EVEN SHOW SHOWERS. WHILE THIS
WILL BE LIGHT GIVEN LIMITED OVERALL FORCING...WITH THE GUSTY WINDS
AND THE LOWERING WATER CONTENT OF THE SNOW...THERE MAY BE SOME
MARKEDLY REDUCED VISIBILITIES IF AND WHERE SOME OF THIS SNOW
IS ABLE MATERIALIZE ACROSS FAR NORTHERN IL MONDAY EVE.
FOR TUESDAY AND BEYOND...THE COLD AIR ADVECTION CONTINUES TO
REINFORCE ITSELF WITH MULTIPLE COLD FRONTS AND MASSIVE CYCLONIC
FLOW. THIS FLOW WILL KEEP THE POTENTIAL FOR AT LEAST
STRATOCU...ALONG WITH THE CHANCE FOR SNOW SHOWERS.
HOWEVER...TEMPERATURES WERE THE FOCUS...AND THEY LOOK TO BE
REMARKABLY LOW FOR THE LATTER HALF OF MARCH. 850MB TEMPERATURES
ARE FORECAST TO DROP TO AROUND -15C TUE MORNING AND THEN AGAIN WED
MORNING. THE SURFACE WIND COMPONENT REMAINS ELEVATED THROUGH
WED...BUT STILL NIGHTTIME TEMPERATURES WILL FALL INTO THE TEENS
AREA WIDE THANKS TO THE COLD AIR ADVECTION. HIGHS WILL NOT REBOUND
MUCH...AND IN SOME PLACES WILL REMAIN BELOW 30F ON WEDNESDAY. IN
FACT...THE LOW MAXIMUM TEMPERATURE RECORD FOR WED IN ROCKFORD OF
ONLY 22F LOOKS TO BE POTENTIALLY IN JEOPARDY. THE SURFACE
HIGH BUILDS IN LATER THU THROUGH THE EARLY PART OF THE WEEKEND.
WITH THE BLOCKED FLOW...THE COLD AIR MASS HAS NO WHERE TO GO BUT
REINFORCE ITSELF FROM THE NORTH. AND ON THAT NOTE...BACKWARDS
TRAJECTORIES FROM THE GFS FOR WED INDICATE PARCELS ORIGINATING FROM
60 DEGREES NORTH LATITUDE /THE BORDER OF THE NORTHERN AND
SOUTHERN CANADIAN PROVINCES/. ALSO CONSIDERING THE EXTENT OF THE
SNOW COVER TO OUR NORTHWEST...WHICH WILL EXPAND TONIGHT INTO
MONDAY...LITTLE AIR MASS MODIFICATION IS ABLE TO OCCUR.
QUITE FASCINATING FOR LATE MARCH!
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* GUSTY NORTHEAST TO EAST WINDS...BECOMING EAST TO SOUTHEAST THIS
EVENING.
* CHANCES OF MIXED PRECIPITATION INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
PAW
//DISCUSSION...UPDATED 18Z...
CEILINGS AT MVFR/VFR LEVELS THAT PUSHED INLAND FROM LAKE MICHIGAN
THIS MORNING WILL BECOME SCATTERED CLOUDS BY LATE THIS AFTERNOON
AS THE LOW LEVEL FLOW TURNS MORE TO THE EAST-SOUTHEAST AND BECOMES
LESS FAVORABLE FOR LAKE EFFECT CLOUDS.
A LOW PRESSURE SYSTEM WILL MOVE FROM THE NORTHERN PLAINS TO LAKE
SUPERIOR THROUGH MONDAY NIGHT. A PUSH OF RELATIVELY WARM AND MOIST
AIR WILL WORK INTO NORTHERN ILLINOIS AND NORTHWEST INDIANA TONIGHT
AHEAD OF THE SYSTEM...AND WILL LEAD TO PRECIPITATION DEVELOPMENT
MONDAY MORNING. START TIME DEPENDS ON WHEN THE LOW LEVELS BECOME
SATURATED AND MAY NEED TO BE ADJUSTED AS DETAILS BECOME CLEARER.
TEMPERATURE FORECASTS SUPPORT MIXED PRECIPITATION WITH A GOOD
CHANCE FOR A PERIOD OF FREEZING RAIN AT THE START. CEILINGS WILL
DROP QUICKLY WHEN PRECIPITATION BEGINS...WITH LOW END MVFR LIKELY
AND IFR POSSIBLE. THE WHOLE SYSTEM WILL MOVE FAIRLY QUICKLY AND
THE PRECIPITATION WILL TAPER OFF BY LATE MONDAY AFTERNOON AND
EVENING.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
233 PM CDT
MAIN CONCERN FOR THE MARINE FORECAST WILL BE PERIOD OF GALES
POSSIBLE MONDAY EVENING THROUGH LATE TUESDAY. TODAY...HIGH PRESSURE
IS CENTERED OVER THE GREAT LAKES REGION PROVIDING DIMINISHING
EAST/NORTHEAST FLOW ACROSS LAKE MICHIGAN. TWO AREAS OF LOW PRESSURE
ARE TAKING SHAPE...ONE ACROSS THE NORTHERN ROCKIES AND THE SECOND
OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY. THE NORTHERN LOW
IS EXPECTED TO MOVE EAST INTO MINNESOTA TONIGHT WITH WINDS OVER THE
LAKE BECOMING SOUTHEAST AND INCREASING INTO THE 20 TO 25 KT POSSIBLY
30 KT RANGE. THE GRADIENT AHEAD OF THE LOW THEN QUICKLY DIMINISHES
MONDAY AS THE LOW MOVES INTO WISCONSIN AND BROAD TROUGHING TAKES
PLACES ACROSS LAKE MICHIGAN BETWEEN THE NORTHERN LOW...AND THE
SOUTHERN LOW AS IT MOVES INTO THE SOUTHERN APPALACHIANS. THIS SHOULD
ALLOW WINDS TO DIMINISH FOR A SHORT PERIOD DURING THE DAY MONDAY
BEFORE WINDS TURN SOUTHWEST...THEN WEST AND QUICKLY INCREASE AGAIN
AS THE NORTHERN LOW MOVES EAST OF LAKE MICHIGAN. WITH THE GRADIENT
QUICKLY STRENGTHENS AND STRONG HEIGHT RISES MOVING IN BEHIND THE
DEPARTING LOW...GALES ARE EXPECTED ACROSS PORTIONS OF LAKE MICHIGAN.
CURRENTLY...THE BEST CHANCES FOR GALES APPEAR ACROSS THE SOUTHERN
HALF TO TWO THIRDS OF THE LAKE...WITH THE GRADIENT SLIGHTLY WEAKER
ACROSS FAR NORTHERN LAKE MICHIGAN CLOSER TO THE LOW TRACK. WILL
ISSUE A GALE WATCH FOR THESE AREAS MONDAY EVENING THROUGH TUESDAY
EVENING. WINDS REMAIN ELEVATED AROUND 30 KT THROUGH THE DAY
WEDNESDAY BEFORE GRADUALLY TAPERING LATE IN THE WEEK.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
242 PM CDT SUN MAR 17 2013
.DISCUSSION...
1010 AM CDT
JUST A FEW CHANGES MADE TO GOING FORECAST FOR TODAY...SIMPLY JUST
TO TOUCH UP HOURLY FORECAST TRENDS.
A STRONG CANADIAN HIGH PRESSURE CENTERED OVER THE NORTHERN LAKES
/RESPONSIBLE FOR -20F TO -30F LOWS OVER NORTHERN MN THIS MORNING/
IS HELPING TO DRIVE AN ENE WIND ACROSS THE AREA THAT WILL SHIFT
MORE DUE EAST THIS AFTERNOON. THE FLOW OFF THE LAKE HAS USHERED IN
AN UNSTABLE BOUNDARY LAYER WITH 850MB DELTA T VALUES AROUND -10C
TO -12C. WHILE SHALLOW...THIS STILL IS SUPPORTIVE OF CLOUDS AND
THE VISIBLE SATELLITE TREND INDICATES AN AXIS THAT HAS SWUNG WEST
FROM MID-LAKE NEAR DAYBREAK. THIS WILL CONTINUE TO SHIFT INLAND AND
LIKELY REACH ALL THE WAY TO ROCKFORD PER DISTANCE SPEED TRACKING
ALONG WITH RH SOLUTIONS FROM LOCAL ARW GUIDANCE. THICK HIGH
CLOUDS WILL CONTINUE TO STREAM ACROSS THE SOUTHEAST ALONG THE MID-
LEVEL BAROCLINIC ZONE...AND HAVE TAKEN MAX TEMPS DOWN ONE TO TWO
DEGREES TOWARD GIBSON CITY AND FOWLER.
EARLY LOOK AT TONIGHT INTO MONDAY INDICATES NO MAJOR IMMINENT
CHANGES TO THE FORECAST. THE TWO PRIMARY SHORT WAVES MENTIONED IN
THE PREV DISCUSSION MATCH UP WELL WITH THE NAM ANALYSIS AND
MORNING UPPER AIR CHARTS. LOOKING AT FORECAST SOUNDINGS FROM THE
NEW NAM AS WELL AS PREVIOUS GUIDANCE...PRECIP TONIGHT STILL
PRESENTS CONCERNS THAT COULD BE FREEZING WHERE IT IS
OCCURRING...WITH AROUND HALF OF THE PRECIP-PRODUCING 17.03 SREF
MEMBERS YIELDING FREEZING PRECIP AS FAR NORTH AS AT LEAST ORD
EARLY MONDAY MORNING. WILL LIKELY HAVE TO ADD A HUNDREDTH OR SO OF
ICE ACCUMULATION IN A PORTION OF THE SOUTHEAST HALF OR TWO-THIRDS OF
THE CWA OR SO...BUT WHERE PRECISELY STILL NEEDS TO BE FURTHER
ANALYZED AND REFINED. THE FAR SOUTHEAST WOULD RUN THE RISK OF
SEEING A LITTLE MORE ACCUMULATION DUE TO GETTING INTO THE BETTER
MOISTURE TRANSPORT AND ISENTROPIC ASCENT WITH TONIGHTS SOUTHERN
STREAM WAVE...ALTHOUGH THEIR SURFACE TEMPS MAY SUPPORT JUST LIQUID
RAIN. OTHERWISE...THE LIKELY SNOW AS THE PRIMARY PRECIP TYPE
ACROSS THE NORTH MONDAY MORNING AND EARLY AFTERNOON LOOKS GOOD.
MAY HAVE TO RE-INTRODUCE SOME LIGHT SNOW/FLURRY CHANCES ACROSS FAR
NORTHERN IL MONDAY NIGHT WITH THE UPPER LEVEL LOW PIVOTING ACROSS
WI...BUT DOES NOT LOOK LIKE MUCH FOR ACCUM IN THAT PERIOD WITH THE
BIGGER STORY BEING FALLING TEMPS AND WIND CHILLS.
MTF
//PREV DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* GUSTY NORTHEAST TO EAST WINDS...BECOMING EAST TO SOUTHEAST THIS
EVENING.
* CHANCES OF MIXED PRECIPITATION INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
PAW
//DISCUSSION...UPDATED 18Z...
CEILINGS AT MVFR/VFR LEVELS THAT PUSHED INLAND FROM LAKE MICHIGAN
THIS MORNING WILL BECOME SCATTERED CLOUDS BY LATE THIS AFTERNOON
AS THE LOW LEVEL FLOW TURNS MORE TO THE EAST-SOUTHEAST AND BECOMES
LESS FAVORABLE FOR LAKE EFFECT CLOUDS.
A LOW PRESSURE SYSTEM WILL MOVE FROM THE NORTHERN PLAINS TO LAKE
SUPERIOR THROUGH MONDAY NIGHT. A PUSH OF RELATIVELY WARM AND MOIST
AIR WILL WORK INTO NORTHERN ILLINOIS AND NORTHWEST INDIANA TONIGHT
AHEAD OF THE SYSTEM...AND WILL LEAD TO PRECIPITATION DEVELOPMENT
MONDAY MORNING. START TIME DEPENDS ON WHEN THE LOW LEVELS BECOME
SATURATED AND MAY NEED TO BE ADJUSTED AS DETAILS BECOME CLEARER.
TEMPERATURE FORECASTS SUPPORT MIXED PRECIPITATION WITH A GOOD
CHANCE FOR A PERIOD OF FREEZING RAIN AT THE START. CEILINGS WILL
DROP QUICKLY WHEN PRECIPITATION BEGINS...WITH LOW END MVFR LIKELY
AND IFR POSSIBLE. THE WHOLE SYSTEM WILL MOVE FAIRLY QUICKLY AND
THE PRECIPITATION WILL TAPER OFF BY LATE MONDAY AFTERNOON AND
EVENING.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
233 PM CDT
MAIN CONCERN FOR THE MARINE FORECAST WILL BE PERIOD OF GALES
POSSIBLE MONDAY EVENING THROUGH LATE TUESDAY. TODAY...HIGH PRESSURE
IS CENTERED OVER THE GREAT LAKES REGION PROVIDING DIMINISHING
EAST/NORTHEAST FLOW ACROSS LAKE MICHIGAN. TWO AREAS OF LOW PRESSURE
ARE TAKING SHAPE...ONE ACROSS THE NORTHERN ROCKIES AND THE SECOND
OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY. THE NORTHERN LOW
IS EXPECTED TO MOVE EAST INTO MINNESOTA TONIGHT WITH WINDS OVER THE
LAKE BECOMING SOUTHEAST AND INCREASING INTO THE 20 TO 25 KT POSSIBLY
30 KT RANGE. THE GRADIENT AHEAD OF THE LOW THEN QUICKLY DIMINISHES
MONDAY AS THE LOW MOVES INTO WISCONSIN AND BROAD TROUGHING TAKES
PLACES ACROSS LAKE MICHIGAN BETWEEN THE NORTHERN LOW...AND THE
SOUTHERN LOW AS IT MOVES INTO THE SOUTHERN APPALACHIANS. THIS SHOULD
ALLOW WINDS TO DIMINISH FOR A SHORT PERIOD DURING THE DAY MONDAY
BEFORE WINDS TURN SOUTHWEST...THEN WEST AND QUICKLY INCREASE AGAIN
AS THE NORTHERN LOW MOVES EAST OF LAKE MICHIGAN. WITH THE GRADIENT
QUICKLY STRENGTHENS AND STRONG HEIGHT RISES MOVING IN BEHIND THE
DEPARTING LOW...GALES ARE EXPECTED ACROSS PORTIONS OF LAKE MICHIGAN.
CURRENTLY...THE BEST CHANCES FOR GALES APPEAR ACROSS THE SOUTHERN
HALF TO TWO THIRDS OF THE LAKE...WITH THE GRADIENT SLIGHTLY WEAKER
ACROSS FAR NORTHERN LAKE MICHIGAN CLOSER TO THE LOW TRACK. WILL
ISSUE A GALE WATCH FOR THESE AREAS MONDAY EVENING THROUGH TUESDAY
EVENING. WINDS REMAIN ELEVATED AROUND 30 KT THROUGH THE DAY
WEDNESDAY BEFORE GRADUALLY TAPERING LATE IN THE WEEK.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
234 PM CDT SUN MAR 17 2013
.DISCUSSION...
1010 AM CDT
JUST A FEW CHANGES MADE TO GOING FORECAST FOR TODAY...SIMPLY JUST
TO TOUCH UP HOURLY FORECAST TRENDS.
A STRONG CANADIAN HIGH PRESSURE CENTERED OVER THE NORTHERN LAKES
/RESPONSIBLE FOR -20F TO -30F LOWS OVER NORTHERN MN THIS MORNING/
IS HELPING TO DRIVE AN ENE WIND ACROSS THE AREA THAT WILL SHIFT
MORE DUE EAST THIS AFTERNOON. THE FLOW OFF THE LAKE HAS USHERED IN
AN UNSTABLE BOUNDARY LAYER WITH 850MB DELTA T VALUES AROUND -10C
TO -12C. WHILE SHALLOW...THIS STILL IS SUPPORTIVE OF CLOUDS AND
THE VISIBLE SATELLITE TREND INDICATES AN AXIS THAT HAS SWUNG WEST
FROM MID-LAKE NEAR DAYBREAK. THIS WILL CONTINUE TO SHIFT INLAND AND
LIKELY REACH ALL THE WAY TO ROCKFORD PER DISTANCE SPEED TRACKING
ALONG WITH RH SOLUTIONS FROM LOCAL ARW GUIDANCE. THICK HIGH
CLOUDS WILL CONTINUE TO STREAM ACROSS THE SOUTHEAST ALONG THE MID-
LEVEL BAROCLINIC ZONE...AND HAVE TAKEN MAX TEMPS DOWN ONE TO TWO
DEGREES TOWARD GIBSON CITY AND FOWLER.
EARLY LOOK AT TONIGHT INTO MONDAY INDICATES NO MAJOR IMMINENT
CHANGES TO THE FORECAST. THE TWO PRIMARY SHORT WAVES MENTIONED IN
THE PREV DISCUSSION MATCH UP WELL WITH THE NAM ANALYSIS AND
MORNING UPPER AIR CHARTS. LOOKING AT FORECAST SOUNDINGS FROM THE
NEW NAM AS WELL AS PREVIOUS GUIDANCE...PRECIP TONIGHT STILL
PRESENTS CONCERNS THAT COULD BE FREEZING WHERE IT IS
OCCURRING...WITH AROUND HALF OF THE PRECIP-PRODUCING 17.03 SREF
MEMBERS YIELDING FREEZING PRECIP AS FAR NORTH AS AT LEAST ORD
EARLY MONDAY MORNING. WILL LIKELY HAVE TO ADD A HUNDREDTH OR SO OF
ICE ACCUMULATION IN A PORTION OF THE SOUTHEAST HALF OR TWO-THIRDS OF
THE CWA OR SO...BUT WHERE PRECISELY STILL NEEDS TO BE FURTHER
ANALYZED AND REFINED. THE FAR SOUTHEAST WOULD RUN THE RISK OF
SEEING A LITTLE MORE ACCUMULATION DUE TO GETTING INTO THE BETTER
MOISTURE TRANSPORT AND ISENTROPIC ASCENT WITH TONIGHTS SOUTHERN
STREAM WAVE...ALTHOUGH THEIR SURFACE TEMPS MAY SUPPORT JUST LIQUID
RAIN. OTHERWISE...THE LIKELY SNOW AS THE PRIMARY PRECIP TYPE
ACROSS THE NORTH MONDAY MORNING AND EARLY AFTERNOON LOOKS GOOD.
MAY HAVE TO RE-INTRODUCE SOME LIGHT SNOW/FLURRY CHANCES ACROSS FAR
NORTHERN IL MONDAY NIGHT WITH THE UPPER LEVEL LOW PIVOTING ACROSS
WI...BUT DOES NOT LOOK LIKE MUCH FOR ACCUM IN THAT PERIOD WITH THE
BIGGER STORY BEING FALLING TEMPS AND WIND CHILLS.
MTF
//PREV DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* LAKE EFFECT MVFR/VFR CIGS BECOMING SCATTERED CLOUDS MID TO LATE
AFTERNOON.
* GUSTY NORTHEAST TO EAST WINDS...BECOMING EAST TO SOUTHEAST THIS
EVENING.
* CHANCES OF MIXED PRECIPITATION INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
PAW
//DISCUSSION...UPDATED 18Z...
CEILINGS AT MVFR/VFR LEVELS THAT PUSHED INLAND FROM LAKE MICHIGAN
THIS MORNING WILL BECOME SCATTERED CLOUDS BY LATE THIS AFTERNOON
AS THE LOW LEVEL FLOW TURNS MORE TO THE EAST-SOUTHEAST AND BECOMES
LESS FAVORABLE FOR LAKE EFFECT CLOUDS.
A LOW PRESSURE SYSTEM WILL MOVE FROM THE NORTHERN PLAINS TO LAKE
SUPERIOR THROUGH MONDAY NIGHT. A PUSH OF RELATIVELY WARM AND MOIST
AIR WILL WORK INTO NORTHERN ILLINOIS AND NORTHWEST INDIANA TONIGHT
AHEAD OF THE SYSTEM...AND WILL LEAD TO PRECIPITATION DEVELOPMENT
MONDAY MORNING. START TIME DEPENDS ON WHEN THE LOW LEVELS BECOME
SATURATED AND MAY NEED TO BE ADJUSTED AS DETAILS BECOME CLEARER.
TEMPERATURE FORECASTS SUPPORT MIXED PRECIPITATION WITH A GOOD
CHANCE FOR A PERIOD OF FREEZING RAIN AT THE START. CEILINGS WILL
DROP QUICKLY WHEN PRECIPITATION BEGINS...WITH LOW END MVFR LIKELY
AND IFR POSSIBLE. THE WHOLE SYSTEM WILL MOVE FAIRLY QUICKLY AND
THE PRECIPITATION WILL TAPER OFF BY LATE MONDAY AFTERNOON AND
EVENING.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE IN DETAILS OF MVFR/VFR CEILINGS.
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
233 PM CDT
MAIN CONCERN FOR THE MARINE FORECAST WILL BE PERIOD OF GALES
POSSIBLE MONDAY EVENING THROUGH LATE TUESDAY. TODAY...HIGH PRESSURE
IS CENTERED OVER THE GREAT LAKES REGION PROVIDING DIMINISHING
EAST/NORTHEAST FLOW ACROSS LAKE MICHIGAN. TWO AREAS OF LOW PRESSURE
ARE TAKING SHAPE...ONE ACROSS THE NORTHERN ROCKIES AND THE SECOND
OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY. THE NORTHERN LOW
IS EXPECTED TO MOVE EAST INTO MINNESOTA TONIGHT WITH WINDS OVER THE
LAKE BECOMING SOUTHEAST AND INCREASING INTO THE 20 TO 25 KT POSSIBLY
30 KT RANGE. THE GRADIENT AHEAD OF THE LOW THEN QUICKLY DIMINISHES
MONDAY AS THE LOW MOVES INTO WISCONSIN AND BROAD TROUGHING TAKES
PLACES ACROSS LAKE MICHIGAN BETWEEN THE NORTHERN LOW...AND THE
SOUTHERN LOW AS IT MOVES INTO THE SOUTHERN APPALACHIANS. THIS SHOULD
ALLOW WINDS TO DIMINISH FOR A SHORT PERIOD DURING THE DAY MONDAY
BEFORE WINDS TURN SOUTHWEST...THEN WEST AND QUICKLY INCREASE AGAIN
AS THE NORTHERN LOW MOVES EAST OF LAKE MICHIGAN. WITH THE GRADIENT
QUICKLY STRENGTHENS AND STRONG HEIGHT RISES MOVING IN BEHIND THE
DEPARTING LOW...GALES ARE EXPECTED ACROSS PORTIONS OF LAKE MICHIGAN.
CURRENTLY...THE BEST CHANCES FOR GALES APPEAR ACROSS THE SOUTHERN
HALF TO TWO THIRDS OF THE LAKE...WITH THE GRADIENT SLIGHTLY WEAKER
ACROSS FAR NORTHERN LAKE MICHIGAN CLOSER TO THE LOW TRACK. WILL
ISSUE A GALE WATCH FOR THESE AREAS MONDAY EVENING THROUGH TUESDAY
EVENING. WINDS REMAIN ELEVATED AROUND 30 KT THROUGH THE DAY
WEDNESDAY BEFORE GRADUALLY TAPERING LATE IN THE WEEK.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
GALE WATCH...LMZ080-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ872-LMZ874-LMZ876-LMZ878...10 PM MONDAY TO 9 PM
TUESDAY.
GALE WATCH...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1239 PM CDT SUN MAR 17 2013
.DISCUSSION...
1010 AM CDT
JUST A FEW CHANGES MADE TO GOING FORECAST FOR TODAY...SIMPLY JUST
TO TOUCH UP HOURLY FORECAST TRENDS.
A STRONG CANADIAN HIGH PRESSURE CENTERED OVER THE NORTHERN LAKES
/RESPONSIBLE FOR -20F TO -30F LOWS OVER NORTHERN MN THIS MORNING/
IS HELPING TO DRIVE AN ENE WIND ACROSS THE AREA THAT WILL SHIFT
MORE DUE EAST THIS AFTERNOON. THE FLOW OFF THE LAKE HAS USHERED IN
AN UNSTABLE BOUNDARY LAYER WITH 850MB DELTA T VALUES AROUND -10C
TO -12C. WHILE SHALLOW...THIS STILL IS SUPPORTIVE OF CLOUDS AND
THE VISIBLE SATELLITE TREND INDICATES AN AXIS THAT HAS SWUNG WEST
FROM MID-LAKE NEAR DAYBREAK. THIS WILL CONTINUE TO SHIFT INLAND AND
LIKELY REACH ALL THE WAY TO ROCKFORD PER DISTANCE SPEED TRACKING
ALONG WITH RH SOLUTIONS FROM LOCAL ARW GUIDANCE. THICK HIGH
CLOUDS WILL CONTINUE TO STREAM ACROSS THE SOUTHEAST ALONG THE MID-
LEVEL BAROCLINIC ZONE...AND HAVE TAKEN MAX TEMPS DOWN ONE TO TWO
DEGREES TOWARD GIBSON CITY AND FOWLER.
EARLY LOOK AT TONIGHT INTO MONDAY INDICATES NO MAJOR IMMINENT
CHANGES TO THE FORECAST. THE TWO PRIMARY SHORT WAVES MENTIONED IN
THE PREV DISCUSSION MATCH UP WELL WITH THE NAM ANALYSIS AND
MORNING UPPER AIR CHARTS. LOOKING AT FORECAST SOUNDINGS FROM THE
NEW NAM AS WELL AS PREVIOUS GUIDANCE...PRECIP TONIGHT STILL
PRESENTS CONCERNS THAT COULD BE FREEZING WHERE IT IS
OCCURRING...WITH AROUND HALF OF THE PRECIP-PRODUCING 17.03 SREF
MEMBERS YIELDING FREEZING PRECIP AS FAR NORTH AS AT LEAST ORD
EARLY MONDAY MORNING. WILL LIKELY HAVE TO ADD A HUNDREDTH OR SO OF
ICE ACCUMULATION IN A PORTION OF THE SOUTHEAST HALF OR TWO-THIRDS OF
THE CWA OR SO...BUT WHERE PRECISELY STILL NEEDS TO BE FURTHER
ANALYZED AND REFINED. THE FAR SOUTHEAST WOULD RUN THE RISK OF
SEEING A LITTLE MORE ACCUMULATION DUE TO GETTING INTO THE BETTER
MOISTURE TRANSPORT AND ISENTROPIC ASCENT WITH TONIGHTS SOUTHERN
STREAM WAVE...ALTHOUGH THEIR SURFACE TEMPS MAY SUPPORT JUST LIQUID
RAIN. OTHERWISE...THE LIKELY SNOW AS THE PRIMARY PRECIP TYPE
ACROSS THE NORTH MONDAY MORNING AND EARLY AFTERNOON LOOKS GOOD.
MAY HAVE TO RE-INTRODUCE SOME LIGHT SNOW/FLURRY CHANCES ACROSS FAR
NORTHERN IL MONDAY NIGHT WITH THE UPPER LEVEL LOW PIVOTING ACROSS
WI...BUT DOES NOT LOOK LIKE MUCH FOR ACCUM IN THAT PERIOD WITH THE
BIGGER STORY BEING FALLING TEMPS AND WIND CHILLS.
MTF
//PREV DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* LAKE EFFECT MVFR/VFR CIGS BECOMING SCATTERED CLOUDS MID TO LATE
AFTERNOON.
* GUSTY NORTHEAST TO EAST WINDS...BECOMING EAST TO SOUTHEAST THIS
EVENING.
* CHANCES OF MIXED PRECIPITATION INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
PAW
//DISCUSSION...UPDATED 18Z...
CEILINGS AT MVFR/VFR LEVELS THAT PUSHED INLAND FROM LAKE MICHIGAN
THIS MORNING WILL BECOME SCATTERED CLOUDS BY LATE THIS AFTERNOON
AS THE LOW LEVEL FLOW TURNS MORE TO THE EAST-SOUTHEAST AND BECOMES
LESS FAVORABLE FOR LAKE EFFECT CLOUDS.
A LOW PRESSURE SYSTEM WILL MOVE FROM THE NORTHERN PLAINS TO LAKE
SUPERIOR THROUGH MONDAY NIGHT. A PUSH OF RELATIVELY WARM AND MOIST
AIR WILL WORK INTO NORTHERN ILLINOIS AND NORTHWEST INDIANA TONIGHT
AHEAD OF THE SYSTEM...AND WILL LEAD TO PRECIPITATION DEVELOPMENT
MONDAY MORNING. START TIME DEPENDS ON WHEN THE LOW LEVELS BECOME
SATURATED AND MAY NEED TO BE ADJUSTED AS DETAILS BECOME CLEARER.
TEMPERATURE FORECASTS SUPPORT MIXED PRECIPITATION WITH A GOOD
CHANCE FOR A PERIOD OF FREEZING RAIN AT THE START. CEILINGS WILL
DROP QUICKLY WHEN PRECIPITATION BEGINS...WITH LOW END MVFR LIKELY
AND IFR POSSIBLE. THE WHOLE SYSTEM WILL MOVE FAIRLY QUICKLY AND
THE PRECIPITATION WILL TAPER OFF BY LATE MONDAY AFTERNOON AND
EVENING.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE IN DETAILS OF MVFR/VFR CEILINGS.
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
324 AM CDT
HIGH PRESSURE IS MOVING SOUTHEASTWARD TOWARD THE WESTERN GREAT LAKES
THIS MORNING WHILE A WEAK SURFACE LOW MOVES ACROSS EASTERN ONTARIO.
A TIGHT PRESSURE GRADIENT IS IN PLACE BETWEEN THESE TWO SYSTEMS WITH
STRONG NORTH-NORTHWEST WINDS BLOWING ACROSS MUCH OF THE CENTRAL AND
NORTHERN SECTIONS OF LAKE MICHIGAN. WINDS WILL DIMINISH THROUGH THE
MORNING ACROSS MOST OF THE LAKE AS THE HIGH MOVES OVERHEAD BUT THERE
WILL BE ENOUGH OF A PRESSURE GRADIENT IN PLACE TO THE SOUTH OF THE
HIGH OR ACROSS SOUTHERN LAKE MICHIGAN TO KEEP SLIGHTLY HIGHER WIND
SPEEDS GOING. WIND DIRECTION WILL SHIFT FROM NORTH-NORTHWEST TO EAST
THEN SOUTHEAST INTO THIS EVENING. SPEEDS WILL THEN INCREASE ACROSS
THE LAKE THIS EVENING AS THE HIGH DEPARTS TO THE EAST AND SURFACE
LOW PRESSURE MOVES EASTWARD ACROSS THE DAKOTAS AND ACROSS LAKE
SUPERIOR AND THE U.P. OF MICHIGAN BY MONDAY NIGHT. WILL GO AHEAD AND
EXTEND THE SMALL CRAFT FOR THE INDIANA NEARSHORE WATERS THROUGH LATE
AFTERNOON TODAY WITH WAVES EXPECTED TO STAY UP WITH THE NORTH TO
NORTHEAST WINDS. WILL ALSO ISSUE A SMALL CRAFT FOR THE ILLINOIS
NEARSHORE WATERS AS THE LONG FETCH OF NORTH THEN NORTHEAST WINDS
WILL BUILD WAVES THIS MORNING. WAVES WILL SUBSIDE LATER IN THE
AFTERNOON BUT WINDS WILL PICK UP TO SMALL CRAFT ADVISORY THRESHOLDS
DURING THE MID OR LATE EVENING WITH WAVES AGAIN BUILDING. WITH THIS
IN MIND WILL RUN THE SMALL CRAFT OUT THROUGH MONDAY MORNING THOUGH
THERE COULD BE A SHORT PERIOD WHERE WAVES FALL BELOW CRITERIA LATE
TODAY AND BEFORE WINDS COME UP ABOVE CRITERIA THIS EVENING.
A FURTHER SHIFT TO SOUTHWEST THEN WEST WINDS WILL OCCUR MONDAY
EVENING. COLDER AIR WILL SPREAD IN INTO TUESDAY AS THE LOW PASSES
AND THE PRESSURE GRADIENT WILL FURTHER STRENGTHEN LEADING TO A
PERIOD OF WEST TO NORTHWEST GALES...LIKELY IN THE 35-40 KT RANGE
STARTING MONDAY EVENING. RIGHT NOW MAINLY THE CENTRAL AND SOUTHERN
PORTIONS OF THE LAKE WILL SEE GALES WHILE THE FAR NORTH REMAINS
UNCERTAIN WITH THE EXPECTED TRACK OF THE LOW SHIFTING SLIGHTLY NORTH
AND SOUTH WITH RECENT FORECAST GUIDANCE. A FURTHER NORTH SOLUTION
WOULD RESULT IN A BETTER CHANCE OF THE NORTHERN THIRD SEEING GALES
AS WELL. SPEEDS WILL EASE LATER TUESDAY AFTERNOON BUT BE SLOW TO
REALLY QUIET DOWN THANKS TO THE LOW SLOWING AS IT PULLS OFF TO THE
EAST AND ANOTHER AREA OF HIGH PRESSURE NOSING INTO THE CENTRAL AND
NORTHERN PLAINS. THE FLOW THEN WEAKENS INTO FRIDAY WITH MAINLY A
NORTH TO NORTHEAST WIND EXPECTED THROUGH NEXT WEEKEND.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1104 AM CDT SUN MAR 17 2013
.DISCUSSION...
1010 AM CDT
JUST A FEW CHANGES MADE TO GOING FORECAST FOR TODAY...SIMPLY JUST
TO TOUCH UP HOURLY FORECAST TRENDS.
A STRONG CANADIAN HIGH PRESSURE CENTERED OVER THE NORTHERN LAKES
/RESPONSIBLE FOR -20F TO -30F LOWS OVER NORTHERN MN THIS MORNING/
IS HELPING TO DRIVE AN ENE WIND ACROSS THE AREA THAT WILL SHIFT
MORE DUE EAST THIS AFTERNOON. THE FLOW OFF THE LAKE HAS USHERED IN
AN UNSTABLE BOUNDARY LAYER WITH 850MB DELTA T VALUES AROUND -10C
TO -12C. WHILE SHALLOW...THIS STILL IS SUPPORTIVE OF CLOUDS AND
THE VISIBLE SATELLITE TREND INDICATES AN AXIS THAT HAS SWUNG WEST
FROM MID-LAKE NEAR DAYBREAK. THIS WILL CONTINUE TO SHIFT INLAND AND
LIKELY REACH ALL THE WAY TO ROCKFORD PER DISTANCE SPEED TRACKING
ALONG WITH RH SOLUTIONS FROM LOCAL ARW GUIDANCE. THICK HIGH
CLOUDS WILL CONTINUE TO STREAM ACROSS THE SOUTHEAST ALONG THE MID-
LEVEL BAROCLINIC ZONE...AND HAVE TAKEN MAX TEMPS DOWN ONE TO TWO
DEGREES TOWARD GIBSON CITY AND FOWLER.
EARLY LOOK AT TONIGHT INTO MONDAY INDICATES NO MAJOR IMMINENT
CHANGES TO THE FORECAST. THE TWO PRIMARY SHORT WAVES MENTIONED IN
THE PREV DISCUSSION MATCH UP WELL WITH THE NAM ANALYSIS AND
MORNING UPPER AIR CHARTS. LOOKING AT FORECAST SOUNDINGS FROM THE
NEW NAM AS WELL AS PREVIOUS GUIDANCE...PRECIP TONIGHT STILL
PRESENTS CONCERNS THAT COULD BE FREEZING WHERE IT IS
OCCURRING...WITH AROUND HALF OF THE PRECIP-PRODUCING 17.03 SREF
MEMBERS YIELDING FREEZING PRECIP AS FAR NORTH AS AT LEAST ORD
EARLY MONDAY MORNING. WILL LIKELY HAVE TO ADD A HUNDREDTH OR SO OF
ICE ACCUMULATION IN A PORTION OF THE SOUTHEAST HALF OR TWO-THIRDS OF
THE CWA OR SO...BUT WHERE PRECISELY STILL NEEDS TO BE FURTHER
ANALYZED AND REFINED. THE FAR SOUTHEAST WOULD RUN THE RISK OF
SEEING A LITTLE MORE ACCUMULATION DUE TO GETTING INTO THE BETTER
MOISTURE TRANSPORT AND ISENTROPIC ASCENT WITH TONIGHTS SOUTHERN
STREAM WAVE...ALTHOUGH THEIR SURFACE TEMPS MAY SUPPORT JUST LIQUID
RAIN. OTHERWISE...THE LIKELY SNOW AS THE PRIMARY PRECIP TYPE
ACROSS THE NORTH MONDAY MORNING AND EARLY AFTERNOON LOOKS GOOD.
MAY HAVE TO RE-INTRODUCE SOME LIGHT SNOW/FLURRY CHANCES ACROSS FAR
NORTHERN IL MONDAY NIGHT WITH THE UPPER LEVEL LOW PIVOTING ACROSS
WI...BUT DOES NOT LOOK LIKE MUCH FOR ACCUM IN THAT PERIOD WITH THE
BIGGER STORY BEING FALLING TEMPS AND WIND CHILLS.
MTF
//PREV DISCUSSION...
404 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH CLOUD
TRENDS THROUGH MID DAY...THE POTENTIAL FOR A MIX OF PRECIPITATION
TONIGHT INTO MONDAY...AND WITH BELOW NORMAL TEMPERATURES EXPECTED
THROUGH MUCH OF NEXT WEEK.
IN THE NEAR TERM...LARGE SCALE VORT MAX WELL TO THE NORTHEAST
CONTINUES TO SHIFT EAST WITH SEVERAL RIPPLES OF ENERGY SHIFTING
EAST ACROSS THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY...WHILE
TWO OTHER STRONGER MORE DEFINED MID LEVEL TROUGHS CONTINUE TO
SHIFT EAST ACROSS THE WESTERN CONUS. AT THE SURFACE...A WEAK
TROUGH OF LOW PRESSURE CONTINUES EXIT EAST ACROSS SOUTHERN ONTARIO
WHILE LARGE HIGH PRESSURE BUILDS EAST/SOUTHEAST ACROSS THE REGION.
THIS SURFACE RIDGE HAS BEEN HELPING WITH CLEARING ACROSS THE
REGION THIS MORNING WITH PRIMARILY WISCONSIN OBSERVING THE BULK OF
THIS CLEARING. ALTHOUGH...LATEST TRENDS HAVE THIS CLEARING LINE OF
THIS LOW STRATUS CURRENTLY PUSHING SOUTH/SOUTHEAST THROUGH
NORTHERN ILLINOIS. EXPECT THIS TO CONTINUE OVER THE NEXT SEVERAL
HOURS...UNTIL LOW LEVEL FLOW VEERS MORE TO THE NORTH AND NORTHEAST
TOWARDS THE 12Z TIME FRAME. DURING THIS TIME DO EXPECT THIS
CLEARING TO STOP FOR A TIME BEFORE WHATEVER STRATUS WAS WORKING
ITS WAY SOUTHEAST TO BEGIN MOVING BACK MORE WESTERLY. ALONG WITH
THIS CURRENT STRATUS IN PLACE...LAKE EFFECT CLOUD COVER WILL
CONTINUE TO DEVELOP AND WORK ITS WAY SOUTH DOWN THE LAKE THROUGH
MID MORNING. IN ALL...DO EXPECT LOW LEVEL CLOUD COVER TO LINGER
AROUND THROUGH AT LEAST LATE MORNING BEFORE IT BEGINS TO FINALLY
SHIFT OUT OF THE CWA. LATEST RAP ANALYSIS IS INDICATING MODERATELY
UNSTABLE CONDITIONS OVER THE LAKE WITH DELTA TS SUPPORTIVE OF AT
LEAST CONTINUED CLOUD DEVELOPMENT ALONG THE OUTER FRINGE OF THIS
BUILDING RIDGE OF HIGH PRESSURE. WEAK CONVERGENCE NOTED ON THE
EASTERN SIDE OF THE LAKE IS EXPECTED TO ALSO SHIFT SOUTH WITH TIME
AND EVENTUALLY SETUP BRIEFLY ACROSS SOUTHERN LAKE MICHIGAN. WITH
THESE UNSTABLE CONDITIONS AND WEAK CONVERGENCE NOTED...IT WOULD
NOT BE OUT OF THE QUESTION FOR A BRIEF PERIOD OF AT LEAST FLURRIES
MOVING OFF OF THE LAKE THIS MORNING. INITIALLY OVER INDIANA...AND
THEN ACROSS NORTHEAST ILLINOIS LATER THIS MORNING. DO EXPECT ANY
DEVELOPMENT TO BE BRIEF THIS MORNING...WITH ANY SNOW DEVELOPMENT
TO BE LIGHT AS CONDITIONS OVER THE LAKE NOT SUPPORTIVE OF BETTER
AND PERSISTENT SNOWFALL.
AFTER A QUIET PERIOD LATER TODAY THROUGH EARLY
EVENING...CHALLENGES WITH RESPECT TO APPROACHING PRECIP WILL
PRESENT ITSELF TONIGHT INTO MONDAY. AM MONITORING TWO SEPARATE
FEATURES ACROSS WESTERN CONUS THIS MORNING...ONE EXITING THE FOUR
CORNERS REGION AS WELL AS A STRONGER MID LEVEL TROUGH DROPPING
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE MID LEVEL TROUGH TO
THE SOUTHWEST WILL QUICKLY LIFT NORTHEAST TODAY AND CONTINUE TO
AID IN THE DEVELOPMENT OF THE CURRENT SHOWERS ACROSS THE MID
MISSISSIPPI VALLEY. ALTHOUGH...THIS WAVE AND LARGE SCALE FORCING
WILL FURTHER LIFT NORTHEAST TOWARDS THE SOUTHERN CWA THIS
EVENING...WITH THIS AXIS OF PRECIPITATION LIKEWISE LIFTING NORTH.
GUIDANCE CONTINUES TO VARY WITH THE NORTHWARD PUSH LATER THIS
EVENING...WITH SOME GUIDANCE BRINGING THIS PRECIP ACROSS THE
SOUTHERN TIER OF COUNTIES BY THIS EVENING WHILE OTHERS HAVE THIS
PRECIP STAY COMPLETELY SOUTH/SOUTHEAST OF THE CWA. ALTHOUGH I DO
THINK THE BULK OF THIS PRECIP WILL STAY SOUTH OF THE CWA THIS
EVENING AND OVERNIGHT...DO EXPECT AT LEAST SOME LIGHT PRECIP TO
AFFECT THE SOUTHEAST THIRD OF THE CWA. SO HAVE MAINTAINED CHANCE
POPS...WITH THE HIGHEST POPS MORE TOWARD THE MIDNIGHT TIME FRAME.
PRECIP TYPE WILL BE TRICKY TONIGHT INTO MONDAY AS SEVERAL TYPES OF
PRECIP WILL BE POSSIBLE. THERMAL PROFILES FOR THIS EVENING AND
OVERNIGHT ACROSS THE SOUTHERN CWA ARE SHOWING A BULGE OF WARMER
AIR ALOFT WHILE THE REMAINING OF THE CWA PROFILE REMAINS BELOW
FREEZING. INITIALLY...A RAIN SNOW MIX IS ANTICIPATED BUT AS
TEMPERATURES BEGIN TO DROP TO AROUND FREEZING WHILE THIS WARM
LAYER MAINTAINS ITSELF IF NOT WARMS FURTHER...RAIN OR FREEZING
RAIN WILL LIKELY BE OBSERVED ACROSS THE SOUTHERN CWA. SURFACE
TEMPERATURES WILL BE KEY LATER TONIGHT INTO MONDAY MORNING ACROSS
THE SOUTHERN CWA AS CURRENTLY TEMPS WILL HOVER AROUND FREEZING. IF
TEMPS WERE TO COOL FURTHER BELOW FREEZING...SOME MINOR ICE
ACCUMULATIONS COULD DEVELOP. A SAVING GRACE AT THIS TIME WOULD BE
FOR THE MAJORITY OF THIS PRECIP TO STAY SOUTH OF THE CWA...WITH
LIGHT QPF EXPECTED ACROSS THE CWA. WILL NEED TO CONTINUE TO
MONITOR THIS AREA TONIGHT IF THIS PRECIP WERE TO TRACK FURTHER
NORTH AND TEMPS WERE TO FALL FURTHER BELOW FREEZING.
THE STRONGER MID LEVEL TROUGH WILL WORK ITS WAY EAST ACROSS THE
CENTRAL CONUS TODAY AND TONIGHT...WITH SOME SLOWING IN ITS
EASTWARD PROGRESSION NOTED. LATEST SATELLITE IMAGERY IS SHOWING
THAT THIS FEATURE HAS CLOSED ITSELF OFF WITH SOME GUIDANCE
INDICATING THIS CLOSED WAVE AT LEAST THROUGH A PORTION OF TODAY.
GUIDANCE IS PICKING UP ON THIS SLOWING...WITH GUIDANCE NOT REALLY
BRINGING BETTER FORCING AND PRECIP ACROSS THE CWA UNTIL AFTER
MIDNIGHT AND ESPECIALLY MORE TOWARDS 12Z MONDAY.
NONETHELESS...PRECIP SHOULD ARRIVE EARLY MONDAY MORNING WITH
PRECIP ACROSS THE CENTRAL AND NORTHERN CWA LIKELY TO BE IN THE
FORM OF LIGHT SNOW/SLEET. DONT ANTICIPATE MUCH IN TERMS OF
ACCUMULATION UNTIL BETTER FORCING/PRECIP WORK ITS EAST ACROSS
MAINLY THE NORTHERN THIRD OF THE CWA. COOLING SHOULD SUPPORT MORE
SNOW THROUGH MID DAY WITH SOME MINOR SNOW ACCUMULATIONS OF AROUND
AN INCH POSSIBLE DURING THIS TIME. AS THIS MID LEVEL WAVE SHIFTS
EAST ACROSS THE CWA THROUGH THE REMAINDER OF MONDAY...EXPECT
PRECIP TO EXIT THE CWA LATER IN THE AFTERNOON WITH ONLY THE
NORTHERN TIER OF CONTINUES LIKELY TO OBSERVE LIGHT SNOW WHILE THE
REMAINING CWA OBSERVES EITHER A RAIN/SNOW MIX OR RAIN IN RISING
SURFACE TEMPS. MUCH COLDER AIR THEN WORKS ITS WAY SOUTHEAST ACROSS
THE REGION WITH WELL BELOW NORMAL TEMPS EXPECTED THROUGH THE
REMAINDER OF THE WORK WEEK.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* LAKE EFFECT MVFR/VFR CIGS CONTINUING THROUGH MID AFTERNOON.
* GUSTY NORTHEAST TO EAST WINDS...BECOMING EAST TO SOUTHEAST THIS
EVENING.
* CHANCES OF MIXED PRECIPITATION INCREASE TOWARD DAYBREAK
MONDAY...MVFR CIGS RETURN...IFR POSSIBLE AT TIMES.
PAW
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE CONTINUES TO WORK EASTWARD ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY AND LAKE SUPERIOR. AS A RESULT WINDS HAVE
TURNED NORTH-NORTHEAST ACROSS THE TERMINALS AND WILL SHIFT TO
EAST-NORTHEAST INTO EARLY AFTERNOON. MVFR CIGS HAVE CLEARED ALL
BUT GYY BUT WITH COLD AIR IN PLACE AND WINDS BEING DIRECTED DOWN
LAKE MICHIGAN MVFR LAKE EFFECT CLOUDS ARE EXPECTED TO WORK IN FROM
THE NORTHEAST THROUGH THE MORNING. SURFACE OBS SHOW CONVERGENCE
OVER THE LAKE WITH SATELLITE SHOWING ABUNDANT CLOUD COVER ACROSS
THE NORTHERN PART OF THE LAKE WITH CIRRUS SHROUDING THE VIEW OVER
THE SOUTHERN PART. RADAR MOSAIC DOES SHOW A PATCH OF VERY WEAK
REFLECTIVITY TO THE EAST OF MKE DRIFTING SOUTH-SOUTHWEST WHICH IS
LIKELY CLOUD COVER. SO WITH THIS IN MIND EXPECT THAT GYY WILL
CONTINUE AT MVFR THROUGH THE MORNING AND POSSIBLY EARLY AFTERNOON.
ORD/MDW/DPA SHOULD SEE MVFR CIGS ARRIVE OVER THE NEXT FEW HOURS AS
LOW LEVEL FLOW TURNS MORE NORTHEASTERLY. SOME FLURRIES ARE ALSO
POSSIBLE. THE FLOW WILL THEN TURN MORE EASTERLY ABOVE THE SURFACE
THIS AFTERNOON WHICH WILL SHORTEN THE FETCH DOWN THE LAKE WHILE
TEMPERATURES ALOFT WARM RESULTING IN UNFAVORABLE LAKE EFFECT
PARAMETERS...WHICH WILL ALLOW CLOUDS TO SCATTER. RFD MAY SEE A
PERIOD OF BKN MVFR CIGS TOO BUT HAVE LEFT THEM SCATTERED FOR NOW
WITH THE EXPECTATION THAT CLOUDS WILL SCATTER AS WINDS TURN
EASTERLY ENOUGH TO PUSH THEM AS FAR INLAND AS RFD. TIMING OF
SCATTERING WILL BE TRICKY SO ADJUSTMENTS MAY BE NEEDED.
FOCUS THEN TURNS TO LOW PRESSURE THAT WILL MOVE FROM THE LEE OF
THE NORTHERN ROCKIES TO LAKE SUPERIOR THROUGH MONDAY NIGHT. A PUSH
OF WARM/MOIST AIR WILL LEAD TO PRECIPITATION DEVELOPMENT EARLY
MONDAY MORNING WHICH WILL WORK NORTH AND EAST ACROSS THE
TERMINALS. FORECAST SOUNDINGS SHOW THAT MIXED PRECIPITATION IS
LIKELY WITH A GOOD CHANCE FOR A PERIOD OF FREEZING RAIN ACROSS THE
TERMINALS...BUT SNOW AND SLEET MAY MIX IN AT TIMES. MAY NEED TO
MOVE START TIME UP SLIGHTLY BUT 10Z LOOKS TO BE THE EARLIEST IN
THE CHICAGO AREA AND 09Z OR SO OUT TOWARDS RFD. PRECIPITATION
INTENSITY LOOKS LIGHT BUT SOME MINOR GLAZING OR SLUSHY
ACCUMULATION IS POSSIBLE DURING THE MORNING BEFORE TEMPERATURES
WARM WELL ABOVE FREEZING. CIGS WILL ALSO QUICKLY DROP WITH LOW END
MVFR LIKELY AND IFR POSSIBLE MONDAY MORNING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM CONFIDENCE IN DETAILS OF MVFR/VFR CEILINGS.
* HIGH CONFIDENCE IN WIND TREND.
* MEDIUM CONFIDENCE IN PRECIPITATION TYPE AND TIMING MONDAY
MORNING.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR.
TUESDAY THROUGH SATURDAY...MAINLY VFR.
MDB
&&
.MARINE...
324 AM CDT
HIGH PRESSURE IS MOVING SOUTHEASTWARD TOWARD THE WESTERN GREAT LAKES
THIS MORNING WHILE A WEAK SURFACE LOW MOVES ACROSS EASTERN ONTARIO.
A TIGHT PRESSURE GRADIENT IS IN PLACE BETWEEN THESE TWO SYSTEMS WITH
STRONG NORTH-NORTHWEST WINDS BLOWING ACROSS MUCH OF THE CENTRAL AND
NORTHERN SECTIONS OF LAKE MICHIGAN. WINDS WILL DIMINISH THROUGH THE
MORNING ACROSS MOST OF THE LAKE AS THE HIGH MOVES OVERHEAD BUT THERE
WILL BE ENOUGH OF A PRESSURE GRADIENT IN PLACE TO THE SOUTH OF THE
HIGH OR ACROSS SOUTHERN LAKE MICHIGAN TO KEEP SLIGHTLY HIGHER WIND
SPEEDS GOING. WIND DIRECTION WILL SHIFT FROM NORTH-NORTHWEST TO EAST
THEN SOUTHEAST INTO THIS EVENING. SPEEDS WILL THEN INCREASE ACROSS
THE LAKE THIS EVENING AS THE HIGH DEPARTS TO THE EAST AND SURFACE
LOW PRESSURE MOVES EASTWARD ACROSS THE DAKOTAS AND ACROSS LAKE
SUPERIOR AND THE U.P. OF MICHIGAN BY MONDAY NIGHT. WILL GO AHEAD AND
EXTEND THE SMALL CRAFT FOR THE INDIANA NEARSHORE WATERS THROUGH LATE
AFTERNOON TODAY WITH WAVES EXPECTED TO STAY UP WITH THE NORTH TO
NORTHEAST WINDS. WILL ALSO ISSUE A SMALL CRAFT FOR THE ILLINOIS
NEARSHORE WATERS AS THE LONG FETCH OF NORTH THEN NORTHEAST WINDS
WILL BUILD WAVES THIS MORNING. WAVES WILL SUBSIDE LATER IN THE
AFTERNOON BUT WINDS WILL PICK UP TO SMALL CRAFT ADVISORY THRESHOLDS
DURING THE MID OR LATE EVENING WITH WAVES AGAIN BUILDING. WITH THIS
IN MIND WILL RUN THE SMALL CRAFT OUT THROUGH MONDAY MORNING THOUGH
THERE COULD BE A SHORT PERIOD WHERE WAVES FALL BELOW CRITERIA LATE
TODAY AND BEFORE WINDS COME UP ABOVE CRITERIA THIS EVENING.
A FURTHER SHIFT TO SOUTHWEST THEN WEST WINDS WILL OCCUR MONDAY
EVENING. COLDER AIR WILL SPREAD IN INTO TUESDAY AS THE LOW PASSES
AND THE PRESSURE GRADIENT WILL FURTHER STRENGTHEN LEADING TO A
PERIOD OF WEST TO NORTHWEST GALES...LIKELY IN THE 35-40 KT RANGE
STARTING MONDAY EVENING. RIGHT NOW MAINLY THE CENTRAL AND SOUTHERN
PORTIONS OF THE LAKE WILL SEE GALES WHILE THE FAR NORTH REMAINS
UNCERTAIN WITH THE EXPECTED TRACK OF THE LOW SHIFTING SLIGHTLY NORTH
AND SOUTH WITH RECENT FORECAST GUIDANCE. A FURTHER NORTH SOLUTION
WOULD RESULT IN A BETTER CHANCE OF THE NORTHERN THIRD SEEING GALES
AS WELL. SPEEDS WILL EASE LATER TUESDAY AFTERNOON BUT BE SLOW TO
REALLY QUIET DOWN THANKS TO THE LOW SLOWING AS IT PULLS OFF TO THE
EAST AND ANOTHER AREA OF HIGH PRESSURE NOSING INTO THE CENTRAL AND
NORTHERN PLAINS. THE FLOW THEN WEAKENS INTO FRIDAY WITH MAINLY A
NORTH TO NORTHEAST WIND EXPECTED THROUGH NEXT WEEKEND.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM SUNDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1252 PM CDT SUN MAR 17 2013
.SYNOPSIS...
ISSUED AT 335 AM CDT SUN MAR 17 2013
LATEST SFC ANALYSIS WAS INDICATING LARGE AND SEASONABLY STRONG RIDGE
COMPLEX ENGULFING MUCH OF THE UPPER MIDWEST WITH A NEAR 1030 MB
CENTER JUST NORTH OF THE NORTHWEST CORNER ON MN. SOUTHEAST RETURN
FLOW AND SFC PRESSURE GRADIENT TIGHTENING AND ORGANIZING ACRS THE
NORTHWESTERN HIGH PLAINS IN A REGION ALSO BATHED BY ROBUST PRESSURE
FALLS. ALOFT...WATER VAPOR IMAGERY WAS INDICATING A VIGOROUS UPPER
LEVEL WAVE ROLLING IN OFF THE PACIFIC AND ACRS OR/WA ATTM WITH AN
ASSOCIATED BAROCLINIC LEAF PLUME TO THE LEE OF IT ACRS THE WESTERN
ROCKIES. TO THE SOUTH ALONG TIGHTER LLVL BAROCLINIC RIBBON...AN
ISENTROPIC LIFT PRECIP EVENT WAS ONGOING ACRS KS...MO AND INTO
SOUTHERN IL.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 335 AM CDT SUN MAR 17 2013
TODAY...THE ABOVE MENTIONED STRONG RIDGE OF HIGH PRESSURE WILL LOOK
TO SQUEEZE EASTWARD ACRS THE WESTERN GRT LKS TODAY. AS IT DOES...
IT/S DRYING NORTHEAST TO EASTERLY FETCH IN THE BOUNDARY LAYER OR EVEN
DEEPER SHOULD KEEP MOST OF THE OVERRUNNING PRECIP OFF THE UPGLIDE
PROCESS TO THE SOUTH OF THE CWA. BUT WILL KEEP THE ONGOING MENTION
OF SPRINKLES OR A SLIGHT CHC OF LIGHT RAIN IN THE FAR SOUTH THIS
AFTERNOON. CLOUD COVER AND IT/S EFFECT ON TEMPS THE MAIN CHALLENGE
TODAY. THE RAP SEEMS TO HAVE SOME HANDEL ON CURRENT LLVL STRATUS
TRENDS PUSHING SOUTHWARD. AFTER MUCH OF THESE LOWER CLOUDS PUSH
ALMOST OUT OF THE DVN CWA...THE VEERING NORTHERLY FLOW SUGGESTED
BY THE RAP THEN SLOSHES BACK SOME LOWER LEVEL STRATUS BACK ACRS
MUCH OF THE DVN CWA FROM THE EAST AND NORTHEAST THIS MORNING UNDER
THE ONGOING AND SUBSTANTIAL TRAPPING INVERSION BASED AT H85 TO H75
MB. WITH PLUME OF MID AND UPPER LEVEL CLOUDS STREAMING OFF THE
OVERRUNNING PRECIP AND CONVECTION ACRS KS INTO MO...WITH THE CHANCE
OF THE STRATUS COMING BACK WILL KEEP THE FLAVOR OF THE DAY MOSTLY
CLOUDY ALTHOUGH SOME PEAKS OF SUN AT TIMES PROBABLE NORTH OF I80.
WILL KEEP HIGH TEMPS MAINLY IN THE 30S FOR A CHILLY ST PATRICK/S
DAY...BUT AREAS ALONG AND SOUTH OF I80 MAY GET NEAR 40 WITH SOME
CLOUD THINNING AT TIMES.
TONIGHT...THE DVN CWA TO BE MAINLY IN BETWEEN TWO LIFTING/FORCING
PROCESSES FOR MUCH OF THE NIGHT. THE ABOVE MENTIONED VIGOROUS UPPER
LEVEL WAVE CURRENTLY ACRS THE PACIFIC NORTHWEST WILL CONTINUE TO DIG
ACRS THE NORTHERN PLAINS AND MO RVR VALLEY THROUGH 12Z MON...WITH
UPPER LEVEL TROFFINESS EXTENDING ALL THE WAY DOWN INTO THE
SOUTHEASTERN PLAINS. CONCEPTUALLY THIS SHOULD ALLOW LLVL CYCLOGENESIS
BLOSSOM ACRS THE SOUTHEASTERN PLAINS AN UP THE LOWER TO MID MS RVR
VALLEY. NORTHWESTERN REACHING FLANK OF DEF ZONE PRECIP OFF THIS
FEATURE MAY CLIP THE SOUTHERN AND SOUTHEASTERN CWA THIS EVENING AND
INTO THE OVERNIGHT...BUT DRY LOW TO MID LEVELS WILL HAVE TO BE
OVERCOME. WILL KEEP CHC POPS IN THESE AREAS FOR LIGHT RAIN THIS
EVENING...BECOMING MIXED WITH SNOW OR SLEET INTO EARLY MON MORNING
AS EVAPO COOLING PROCESSES HAVE THEIR AFFECT. SFC TEMPS IN THESE
AREAS WILL BE MARGINAL FOR ANY FREEZING RAIN THREAT AND WILL NOT
MENTION. BUT THE MAIN FORCING EVENT IN VIEW OF THE APPROACHING
DIGGING WAVE WILL LOOK TO OCCUR ACRS THE NORTHEASTERN PLAINS INTO MN
AND IA LATER TONIGHT. DEEPENING SFC LOW PRESSURE TO UNDER 1000 MB TO
ROLL OUT OF THE DAKOTAS AND INTO NORTHWESTERN MN BY 12Z MON. THE
TROF ALMOST TAKING A NEG TILT AS IT DOES SUGGESTS A STRONGLY FORCED
EVENT ACRS THE UPPER MS RVR VALLEY REGION. ASSOCIATED PRECIP SWATH
AHEAD OF THIS PROCESS WILL LOOK TO PUSH ACRS IA AND INTO THE WESTERN/
NORTHWESTERN THIRD OF THE DVN CWA AFTER 08Z MON MORNING MAINLY IN
THE FORM OF SNOW. UPWARD VERTICAL VELOCITIES AND THERMODYNAMIC
PROFILES SUGGEST A BURST OF HEAVY WET SNOW POSSIBLE INTO THE FAR
NORTHWESTERN CWA WHERE UP TO AN INCH OF SNOW MAY OCCUR BY 12Z MON
NORTHWEST OF A CEDAR RAPIDS...TO MANCHESTER IA LINE. UP TO A HALF
INCH POSSIBLE ALONG AND NORTHWEST OF AN IOWA CITY...TO DYERSVILLE
LINE. STILL RATHER MILD SFC/GROUND TEMPS TO ACT AS AN ACCUMULATION
INHIBITOR AND PROMOTE COMPACTION AND MELTING EVENTUALLY. BUT SNOW
RATES BEFORE THE SUN RISES MAY STILL OVERCOME THIS FOR A WHILE TO
ALLOW THE POTENTIAL ACCUMS MENTIONED ABOVE. REST OF THE EVENT COVERED
IN DISCUSSION BELOW. ..12..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 17 2013
SNOW AMOUNTS MONDAY MORNING WILL BE THE MAIN CONCERN FOR THE LONG
TERM. AFTER MONDAY NORTHWEST FLOW TO DOMINATE THE REGION KEEPING
COLD AND DRY CONDITIONS OVER THE AREA INTO THE WEEKEND.
A SHORTWAVE OVER THE PACIFIC NORTHWEST EARLY THIS MORNING IS PROGGED
TO MOVE THROUGH THE MID AND UPPER MISSISSIPPI VALLEY MONDAY. THE
S/W WILL DRAG A STRONG COLD FRONT THROUGH THE REGION MONDAY
AFTERNOON AND EVENING WITH VERY COLD TEMPERATURES RUSHING INTO THE
REGION MONDAY AFTERNOON/NIGHT. THE FORECAST MODELS ARE IN GOOD
AGREEMENT IN SPREADING THE SYNOPTIC FORCING AHEAD OF THIS SYSTEM
OVER THE CWFA MONDAY MORNING WITH THE BETTER FORCING CLIPPING THE
NORTHERN COUNTIES. WITH PW/S EXPECTED TO BE AROUND A HALF INCH OR
SO QPF AMOUNTS OF 1 TO 2 TENTHS OF AN INCH LOOK REASONABLE BETWEEN
12Z AND 18Z. H8 TEMPS MONDAY MORNING WILL BE JUST BELOW ZERO
SUPPORTING SNOW RATIOS AROUND 10 TO 1 EARLY MONDAY MORNING WITH
RATIOS INCREASING TO 15 TO 1 BY LATE MORNING AS THE COLDER AIR
REACHES THE AREA. THE EXPECTED QPF AND SNOW RATIOS SUPPORT SNOWFALL
AMOUNTS IN THE 1 TO 2 INCH RANGE /STORM TOTAL/ NORTH OF I80 WITH THE
LOWER AMOUNTS NEAR I80 AND THE HIGHER AMOUNTS ALONG THE HIGHWAY 20
CORRIDOR. THE BIGGEST IMPACTS FROM THE SNOW MAY BE THE TIMING AND
LOW VISIBILITIES. THE SNOW WILL IMPACT THE MORNING COMMUTE
ESPECIALLY OVER EAST CENTRAL IOWA BUT SURFACE TEMPERATURES DURING
THE SNOW SHOULD BE IN THE UPPER 20S TO LOW 30S SUGGESTING MOST OF
THE SNOW WILL HAVE A DIFFICULT TIME ACCUMULATING ON ROADS. THE
OTHER AREA OF CONCERN WILL BE REDUCED VISIBILITIES. MODELS ARE
SHOWING A NARROW BAND OF FGEN WITH GOOD VERTICAL CONTINUITY AND ON
THE GRADIENT OF STEEPER MID LEVEL LAPSE RATES SUGGESTING A NARROW
BAND OF ENHANCED SNOWFALL RATES. IT ALSO APPEARS THAT THE THERMAL
PROFILES WILL SUPPORT DENDRITIC FLAKES DURING THE PERIOD OF ENHANCED
FORCING. IF THESE CONDITIONS VERIFY THEN VISIBILITIES DROPPING TO A
HALF MILE OR LESS WILL BE POSSIBLE AT TIMES MONDAY MORNING.
THE ACCUMULATING SNOW WILL END BY NOON IN THE NORTHEAST AS THE
BETTER FORCING MOVES EAST OF THE AREA. COLDER AIR AND STRONGER WINDS
MOVE IN DURING THE AFTERNOON CAUSING FALLING TEMPERATURES DURING THE
MID TO LATE AFTERNOON OVER THE NORTHWEST COUNTIES. THE BRISK
CONDITIONS WILL CONTINUE OVER NIGHT AS A SURFACE LOW MOVES THROUGH
THE WESTERN GREAT LAKES AND HIGH PRESSURE BUILDS SOUTHEAST INTO THE
MID/LOWER MISSOURI VALLEY. LOWS TUESDAY MORNING ARE EXPECTED TO
RANGE FROM AROUND 10 IN THE NORTH TO THE MID 20S SOUTH.
THE REST OF THE WEEK LOOKS COLD AND DRY WITH NORTHWEST FLOW
REMAINING OVER THE AREA BETWEEN A BROAD EASTERN US TROF AND RIDGING
OVER THE WESTERN U.S./EASTERN PACIFIC. A REINFORCING SHOT OF COLD
AIR IS PROGGED TO MOVE INTO THE REGION TUESDAY NIGHT RESULTING IN
SINGLE DIGIT LOWS NORTH AND AROUND 20 IN THE SOUTH WEDNESDAY MORNING
AND HIGHS WEDNESDAY IN THE LOW TO MID 20S NORTH TO MID 30S SOUTH.
AFTER WEDNESDAY TEMPERATURES WILL MODERATE A LITTLE WITH HIGHS
EXPECTED TO BE IN THE 30S TO LOW 40S AND LOWS IN THE 20S BY FRIDAY
AND SATURDAY. BUT THESE TEMPERATURES ARE STILL WELL BELOW NORMAL AS
WE APPROACH THE LAST WEEK OF MARCH.
DLF
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1237 PM CDT SUN MAR 17 2013
MVFR TO VFR CIGS EXPECTED FOR MUCH OF TONIGHT. LOW PRESSURE WILL
MOVE FROM THE NORTHERN PLAINS TO LAKE SUPERIOR BY MONDAY NIGHT.
WARM...MOIST ADVECTION IN ADVANCE OF THIS SYSTEM WILL RESULT IN
PRECIPITATION DEVELOPING OVER THE TERMINALS FROM SOUTH TO NORTH
MAINLY OVERNIGHT THROUGH MONDAY MORNING...WITH CONDITIONS LOWERING
TO GENERALLY IFR IN EITHER CIGS AND/OR VSBY. SOUNDINGS SUGGEST
COULD SEE WINTRY MIX OF PRECIPITATION ESPECIALLY AT KBRL AND KMLI
WITH MAINLY SNOW AT KCID AND KDBQ WHERE ACCUMULATIONS OF AN INCH
OR TWO APPEAR LIKELY. PRECIPITATION IS EXPECTED TO END OR TAPER
OFF BY MID TO LATE MORNING FROM SOUTHWEST TO NORTHEAST WITH
CONDITIONS BECOMING MOSTLY MVFR. WINDS EASTERLY AROUND 10 KTS
THROUGH MUCH OF TONIGHT...WITH SOME GUSTS NEAR 18 KTS REST OF THIS
AFTERNOON. LIGHT WINDS MAINLY SOUTHEAST MONDAY TO BECOME WESTERLY
AND INCREASE TO 10-20 KTS BY MIDDAY.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...12
SHORT TERM...12
LONG TERM...DLF
AVIATION...05
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1251 PM CDT SUN MAR 17 2013
...UPDATE TO AVIATION...
.DISCUSSION...
A MIX OF PRECIPITATION WAS OCCURRING ACROSS NORTH CENTRAL AND
NORTHEAST KANSAS NORTH OF INTERSTATE 70 AT 08Z. A MIX OF
RAIN...SLEET AND SNOW HAS BEEN OBSERVED. EXPECT THIS PRECIPITATION
TO MOVE OUT OF THE AREA LATER THIS MORNING. RUC AND SREF SUGGEST
SOME REDEVELOPMENT OF PRECIPITATION IN CENTRAL KANSAS LATER THIS
AFTERNOON AS SHORTWAVE MOVES OUT OF THE ROCKIES. COULD SEE SOME
LIGHT RAIN APPROACHING NORTH CENTRAL KANSAS BY EVENING. ACROSS THE
EAST CENTRAL THIS MORNING WILL SEE THE BEST CHANCES OF PRECIPITATION
SOUTH OF I-35 IN ZONE OF FRONTOGENESIS FROM SOUTH CENTRAL INTO EAST
CENTRAL KANSAS. THERMAL PROFILES WOULD SUGGEST THAT THIS
PRECIPITATION WILL BE ALL LIQUID. TEMPERATURES TODAY WILL ONLY RISE
INTO THE LOWER 40S FOR HIGHS.
SATELLITE WAS SHOWING AN UPPER LEVEL TROUGH MOVING ACROSS THE
PACIFIC NORTHWEST AND THIS SYSTEM WILL DEEPEN AND MOVE ACROSS THE
ROCKIES AND INTO THE NORTHERN AND CENTRAL PLAINS TONIGHT. FORCING
WILL BE MAXIMIZED TO THE NORTH OF THE NEBRASKA BORDER TONIGHT AS THE
PV ANOMALY MOVES ACROSS THE NORTHERN PLAINS...SO EXPECTING ONLY 30
TO 40 PERCENT CHANCES OF PRECIPITATION TONIGHT WITH LITTLE IN THE
WAY OF QPF. THERMAL PROFILES SUGGEST THAT PRECIPITATION WILL BE ALL
RAIN THIS EVENING THEN A MIX OF RAIN AND SNOW NORTH OF HIGHWAY 56
AND RAIN SOUTH. LOWS TONIGHT COOLING INTO THE LOWER TO MID 30S. THE
UPPER TROUGH AXIS SHOULD MOVE OUT OF EASTERN KANSAS TOWARD SUNRISE
MONDAY.
A DRY PERIOD IS EXPECTED FROM MONDAY THROUGH WEDNESDAY WITH A DRY
NORTHWEST FLOW. NEXT SHOT OF PRECIPITATION OCCURS THURSDAY THROUGH
FRIDAY AS WAA INCREASE ALONG WITH ISENTROPIC LIFT AHEAD OF AN
APPROACHING UPPER TROUGH. MODELS ALSO SUGGEST THAT PIECES OF ENERGY
WILL MOVE OUT OF THE ROCKIES ACROSS KANSAS DURING THIS PERIOD. THE
ECMWF IS COOLER WITH THE THERMAL PROFILES AND FORECAST SOUNDINGS
SUGGEST THAT IT WILL BE COLD ENOUGH FOR SNOW AND ALSO A RAIN AND
SNOW MIX. THIS STILL MAY CHANGE WITH LATER RUNS. THE SYSTEM MOVES
OUT LATE FRIDAY WITH DRY WEATHER FOR THE START OF THE WEEKEND.
53
&&
.AVIATION...
MVFR STRATUS EXPECTED TO STICK AROUND FOR REMAINDER OF THE DAY AT
ALL TERMINALS. CIGS WILL LIKELY COME DOWN OVERNIGHT TO IFR LEVELS
WITH PERHAPS A PERIOD OF REDUCED VISIBILITY DUE TO HAZE OR PERHAPS
SOME DRIZZLE. EXPECT SKIES TO RAPIDLY CLEAR EARLY MONDAY
MORNING...WITH CLEAR SKIES FROM ROUGHLY 12Z THROUGH REST OF TAF
PERIOD MONDAY.
JL
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
159 PM EDT SUN MAR 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 526 AM EDT SUN MAR 17 2013
LATEST GFS ANALYSIS SHOWS HIGH LATITUDE POSITIVE HEIGHT ANOMALIES
OVER GREENLAND AND N OF ALASKA WITH A W-E ELONGATED POLAR VORTEX TO
THE S DOMINATING MUCH OF CANADA. CENTER OF VORTEX WAS OVER HUDSON
BAY. SHORTWAVE TROF EXTENDING FROM THE CENTER HAS SWEPT E OF THE
UPPER GREAT LAKES DURING THE NIGHT. IN THE WAKE OF THE WAVE...850MB
TEMP WAS -23C ON 00Z KINL RAOB...AND LATEST RUC ANALYSIS SHOWS 850MB
TEMPS AROUND -20C OVER LAKE SUPERIOR. DESPITE STRONG OVERWATER
INSTABILITY...LES HAS BEEN POORLY ORGANIZED (NO REAL BANDING) AND
GENERALLY LIGHT TO PERHAPS ONLY MDT INTENSITY AT TIMES DESPITE DGZ
DOMINATING CONVECTIVE LAYER AND DESPITE KMQT VAD WIND PROFILE
SHOWING CLOUD TOPS TO 6-7KFT MSL AND NEARLY UNIDIRECTIONAL FLOW THRU
CLOUD DEPTH. DRY ADIABATIC LAPSE RATES BELOW INVERSION PER UPSTREAM
00Z KINL/CWPL SOUNDINGS IS PROBABLY A CONTRIBUTOR TO THE POOR
ORGANIZATION AS IS INFLUX OF DRIER AIR. GIVEN THE LACK OF
ORGANIZATION AND WEAK INTENSITY OF LES...OPTED TO CANCEL LES ADVY
NEAR LAKE SUPERIOR OVER THE E.
SFC HIGH PRES OVER NRN MN WILL QUICKLY MOVE ACROSS THE FCST AREA
TODAY. IN FACT...CENTER SHOULD BE OF THE AREA BY LATE AFTN. AS A
RESULT...ONGOING DIMINISHING LES WILL END W TO E AS NW WINDS BECOME
LIGHT/VRBL THEN SOUTHERLY AFTER SFC HIGH PASSES. MAY SEE AN
ADDITIONAL INCH OF FLUFFY SNOW E OF MARQUETTE IN THE MORNING BEFORE
THE LES ENDS. OTHERWISE...SKIES SHOULD TURN MOSTLY SUNNY W-E AFTER
WIND SHIFT TO THE S FOLLOWING PASSAGE OF THE SFC HIGH PRES. THE DAY
WILL PROBABLY BEGIN MOSTLY SUNNY OVER THE SCNTRL WHERE DOWNSLOPING
IS ALREADY LEADING TO MOSTLY CLEAR SKIES. DESPITE INCREASING
SUNSHINE...HIGH TEMPS WILL ONLY REACH INTO THE 20S WITH 850MB TEMPS
RECOVERING TO -8C TO -12C IN THE AFTN.
DRY WEATHER WILL CONTINUE TONIGHT. HIGH AND THEN MID CLOUDS WILL BE
ON THE INCREASE AHEAD OF VIGOROUS SHORTWAVE THAT IS NOW MOVING
ACROSS THE PACIFIC NW INTO THE NRN ROCKIES. INCREASING CLOUDS AND
INCREASING SE WINDS WILL KEEP TEMPS FROM FALLING SIGNIFICANTLY. SOME
OF THE TRADITIONAL COLD SPOTS MAY DROP TO AROUND 10F...BUT MOST
AREAS SHOULD SEE MINS IN THE MID/UPPER TEENS WITH A SLIGHT RISING
TREND TO TEMPS LATE.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 526 AM EDT SUN MAR 17 2013
PRIMARY FOCUS HAS BEEN AND CONTINUES TO BE UPR TROUGH/LOW PRESSURE
SYSTEM MOVING ACROSS UPPER GREAT LAKES ON MONDAY. IN GENERAL MODELS
INDICATE ADVY SNOW EVENT FOR MUCH OF CWA...BUT AT LEAST AS OF THIS
MORNING DOES NOT APPEAR TO BE A BLOCKBUSTER MARCH STORM BY UPPER
LAKES STANDARDS. ONE REASON SYSTEM IS NOT AS STRONG AS IT COULD BE
IS GULF MOISTURE TRYING TO SURGE NORTHWARD IS INTERCEPTED BY SMALLER
AREA OF SFC-H85 LOW PRESSURE SLIDING FROM SOUTHERN PLAINS INTO OHIO
VALLEY. PWATS INTO THAT AREA ARE WELL OVR 200 PCT OF NORMAL WHILE
THEY STAY ONLY AROUND NORMAL INTO WISCONSIN AND UPR MICHIGAN. SECOND
REASON LARGER SCALE SYSTEM IMPACTING AREA ON MONDAY IS NOT AS STRONG
IS DUE TO LIMITED JET ENHANCEMENT/DEEPENING OF H5 LEVEL LOW AS IT
SLIDES ACROSS UPR LAKES REGION. LAST COUPLE RUNS OF GFS/GEM-NH HAVE
TRENDED A BIT DEEPER WITH SFC-H85 LOWS THOUGH AND THIS RESULTS IN A
WETTER TREND FM THE GFS...WITH 12HR QPF OF 0.25-0.30 INCH OVR MOST
OF WEST HALF OF CWA 18Z MONDAY THROUGH 06Z TUESDAY. LARGE SCALE
ENHANCEMENT FACTORS TO BOOST PRECIP ARE MINOR AS NAM/GFS INDICATE
BRIEF PERIOD OF MOISTURE ADVECTION 850-800MB WITH MINIMAL TEMP
ADVECTION IN THAT LAYER. ALSO THERE IS NO JET SUPPORT AND MINIMAL
FRONTOGENESIS SINCE TEMPERATURE GRADIENT SFC-H85 IS LACKING.
THUS...APPERS THAT MOISTURE ADVECTION AND INCREASING CYCLONIC FLOW
AROUND SFC-H85 LOWS WILL DRIVE THE SNOW. EXPECT MOST SNOW TO OCCUR
THROUGH 00Z TUESDAY OVR SW TIER AND 18-21Z MONDAY THROUGH 03Z
TUESDAY IN THE NORTH AND EAST CWA. CONSENSUS OF MODELS FAVOR THAT
TIMING AND THERE IS GOOD AGREEMENT FROM SREF MEMBERS AS WELL. ONE
MESOSCALE EFFECT THAT MAY RESULT IN MORE SNOW IS POSSIBLE LAKE
ENHANCEMENT WITH ESE BLYR WINDS ON THE KEWEENAW AS H85 TEMPS ARE AT
OR COLDER THAN -8C. SHOWED ENHANCED QPF/SNOW FOR KEWEENAW ON MONDAY
AFTN/EVENING TO ACCOUNT FOR THIS. SLR/S FOR THIS EVENT WILL NOT BE TOO
OFF FROM 16:1 CLIMATOLOGY MARK...IF ANYTHING MAY BE SLIGHTLY LOWER
BUT STILL ABOVE 10:1. OVERALL 3"/12HR SEEMS PROBABLE OVER MUCH OF THE
AREA WHICH IS ADVY CRITERIA. MAYBE MORE SNOW OVER FAR WEST AND ACROSS
KEWEENAW PENINUSLA. WPC WWD GRAPHICS INDICATE 4-6 INCHES FOR THOSE
AREAS...WHICH ACTUALLY LINES UP WELL WITH CURRENT FORECAST THINKING.
SINCE BULK OF SNOW OCCURS LATER IN THE 3RD PERIOD...WILL NOT ISSUE
ANY ADVISORIES FOR SYSTEM SNOW ON MONDAY YET.
LK EFFECT INCREASES ON MONDAY NIGHT INTO TUESDAY FOR AREAS FAVORED
BY WNW-NW FLOW. A MAJORITY OF SNOW FROM THE SYSTEM WILL LIKELY COME
DURING THAT TIME AND ADDITIONAL HEADLINES MAY BE NEEDED INTO
TUESDAY. NAM SOUNDINGS INDICATE DEPTH OF LK EFFECT CONVECTIVE LAYER
BUILDS THROUGHOUT THE NIGHT WITH EQL PEAKING OVER 10KFT BTWN 09Z-12Z
ON TUESDAY IN THE WESTERN CWA AND AROUND 15Z ON TUESDAY IN THE
NORTHEAST CWA. GFS /WHICH IS PREFERRED BY WPC WITH TIMING OF THE
SYSTEM DUE TO ITS CONSISTENCY/ SHOWS SIMILAR SETUP BUT IS SLIGHTLY
SLOWER WITH TIMING. SINCE SOUNDINGS INDICATE MAJORITY OF LK
CONVECTIVE LAYER WITHIN THE DGZ...SLR/S WILL PUSH WELL OVER 20:1.
STRONG WINDS OVER 25 KTS IN THE BLYR WILL CUT SLR/S DOWN SLIGHTLY
THOUGH. HIGH SLR/S WITH PERSISTENT CONVERGENCE AND MORE THAN AMPLE
OVER-WATER INSTABILITY WILL RESULT IN AT LEAST MODERATE LK EFFECT
SNOWS FOR FAVORED AREAS. HINT AT REINFORCING SHOT OF COLDER AIR
LATER TUESDAY NIGHT SO AFTER SLIGHT DIMINISHING TREND INTO TUESDAY
EVENING MAY SEE ANOTHER UPTICK IN LK EFFECT AS THE TROUGH AND COLDER
AIR ARRIVE.
STEADY STATE LK EFFECT SETUP CONTINUES INTO WEDNESDAY NIGHT AND
KEPT CATEGORICAL POPS GOING FOR NW FLOW AREAS. SEVERAL INCHES OF
FLUFFY LK EFFECT SNOW SHOULD ACCUMULATE WEDNESDAY AND WEDNESDAY
NIGHT. ACCUMS IN SOME AREAS LIKELY WILL EXCEED A FOOT IN THE 48 HOUR
TIME FRAME TUESDAY THROUGH WEDNESDAY. OTHER HAZARD WILL BE BLOWING
SNOW AND REDUCED VSBY OVER MUCH OF THE EASTERN CWA AS NW WINDS GUST
OVER 25 KTS THROUGH WEDNESDAY. OCCASIONAL WHITEOUTS SEEM LIKELY...
ESPECIALLY ALONG LK SUPERIOR TUESDAY AFTN THROUGH WEDNESDAY MORNING.
WILL CONTINUE TO MENTION THE PROLONGED PERIOD OF MODERATE-HEAVY LK
EFFECT SNOW AND CONSIDERABLE BLSN IN THE HAZARDOUS WEATHER OUTLOOK.
OUR BACKLOADED WINTER JUST WILL NOT LET GO. LK EFFECT GRADUALLY
DIMINISHES INTO THURSDAY AS LOW PRESSURE TROUGH OVER THE REGION
BEGINS TO RELAX. PROBABLY CAN NOT COUNT OUT LGT LK EFFECT OR FLURRIES
INTO AT LEAST FIRST PART OF NEXT WEEKEND THOUGH AS ECMWF/GFS SHOW
WEAK ONSHORE WINDS CONTINUING BTWN HIGH PRESSURE OVER SCNTRL CANADA
AND TROUGHING OVER EASTERN CANADA/NEW ENGLAND. AFTER TEMPS NEAR 30
DEGREES ON MONDAY AHEAD OF DEVELOPING LOW PRESSURE SYSTEM...DAYTIME
TEMPS FOR THE REST OF THE WEEK WILL BE BLO NORMAL. ONLY GRADUAL
WARMING INTO 30S FOR NEXT WEEKEND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 156 PM EDT SUN MAR 17 2013
WITH SFC HIGH PRES IN CONTROL...DRY LOW-LEVELS WILL CONTINUE KEEPING
VFR CONDITIONS GOING TONIGHT. HOWEVER...UPSLOPE SSE FLOW OFF LAKE
MI COULD RESULT IN MVFR CIGS REDEVELOPING AT KSAW. WILL BE SOMETHING
TO MONITOR INTO THE EVENING HRS TONIGHT. OTHERWISE...TIGHTENING PRES
GRADIENT AND NOCTURNAL INVERSION WILL LIKELY LEAD TO LLWS AT ALL 3
SITES TONIGHT. INCREASING MOISTURE AHEAD OF APPROACHING FRONTAL
SYSTEM WILL CAUSE CIGS TO LOWER BY LATE MON MORNING AT KIWD AND KSAW
AND BY EARLY AFTERNOON AT KCMX. LOOK FOR MVFR CIGS AT BOTH KIWD AND
KSAW BY LATE MON MORNING WITH THE ONSET OF LIGHT SNOW RESTRICTING
VSBY TO MVFR AT KIWD AND THEN MVFR CONDITIONS IN LIGHT SNOW WILL
REACH KCMX BY EARLY MON AFTERNOON.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 526 AM EDT SUN MAR 17 2013
WITH HIGH PRES QUICKLY MOVING ACROSS LAKE SUPERIOR TODAY...EXPECT A
PERIOD OF LIGHT WINDS UNDER 15KT. THE DIMINISHING WINDS/WAVES WILL
BRING AN END TO HVY FREEZING SPRAY EARLY THIS MORNING. AS THE HIGH
CONTINUES E...REACHING NEW ENGLAND MON...LOW PRES EMERGING OVER THE
WRN DAKOTAS THIS AFTN WILL TRACK E...REACHING THE UPPER GREAT LAKES
MON NIGHT. TIGHT PRES GRADIENT BTWN THE DEPARTING HIGH AND
APPROACHING LOW WILL BRING SE WINDS UP TO 30KT TONIGHT AND MON. SOME
GALE FORCE GUSTS TO 35KT WILL BE POSSIBLE LATE TONIGHT/MON OVER
PORTIONS OF NCNTRL AND ERN LAKE SUPERIOR. AFTER THE LOW EXITS TO THE
E...NORTHWEST GALES WILL DEVELOP FROM W TO E LATE MON NIGHT/TUE.
THE GALES WILL THEN CONTINUE INTO WED OVER THE E HALF OF THE LAKE.
WINDS WILL SLOWLY DIMINISH TO UNDER 25KT FROM W TO E WED NIGHT/THU.
THE COMBINATION OF COLD AIR/STRONG WINDS/HIGH WAVES WILL LEAD TO
PERIODS OF HVY FREEZING SPRAY TUE THRU WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS DULUTH MN
109 PM CDT SUN MAR 17 2013
.AVIATION.../18Z TAF ISSUANCE/
VFR CONDITIONS WILL GRADUALLY GIVE WAY TO THICKENING CLOUDS AND
LOWERING CLOUDS BY THIS EVENING. VFR WILL QUICKLY BECOME MVFR
DURING THE EVENING AND THEN IFR/LIFR OVERNIGHT. CIGS AND VSBYS
WILL DROP RAPIDLY AS THE SNOW SPREADS IN FROM A STORM SYSTEM TO
THE WEST OF OUR AREA.
&&
.PREV DISCUSSION... /ISSUED 1006 AM CDT SUN MAR 17 2013/
UPDATE...
THE FORECAST WAS UPDATED THROUGH TONIGHT. THE MAIN CHANGES
WERE TO SKY COVER. IT APPEARS THE COMBINATION OF BKN/OVC MID/LOW
LEVEL CLOUDS IN WESTERN MINNESOTA MOVING TOWARDS THE
NORTHLAND AND INCREASING LOW LEVEL CLOUDS ACROSS THE EASTERN
FORECAST AREA THIS AFTERNOON WILL RESULT IN A GENERALLY INCREASING
CLOUD COVER TREND THROUGH THE AFTERNOON. THE 12Z NAM12 SOUNDINGS
ARE SHOWING THAT CONVECTIVE TEMPERATURES WILL BE REACHED EARLY
THIS AFTERNOON AND LIKELY RESULT IN AT LEAST SOME SCATTERED LOW
LEVEL CLOUDS ACROSS THE EASTERN FORECAST. THIS SHOWS UP TOO IN
RECENT HRRR MODEL RUNS. ALSO...THERE IS PLENTY OF BKN/OVC MID/LOW
LEVEL CLOUDS MOVING THROUGH WESTERN MINNESOTA AND THE EASTERN
DAKOTAS ON PATH TOWARDS THE NORTHLAND...AND THERE DOES NOT APPEAR
TO BE MUCH TO STOP IT AS THE HIGH PRESSURE OVER THE GREAT LAKES
CONTINUES TO MOVE EAST. RECENT MODEL GUIDANCE WAS ALSO SHOWING
LOWER HIGH TEMPERATURES TODAY...WHICH SHOULD MAKE SOME SENSE
CONSIDERING HOW COLD IT GOT THIS MORNING AND THE INCREASING CLOUD
COVER TODAY. THEREFORE...DECREASED THE HIGHS A BIT. UPDATED THE
PCPN TIMING LATE THIS AFTERNOON AND INTO TONIGHT A BIT...BUT DID
NOT YET CHANGE THE PCPN/SNOWFALL FORECAST. I WILL LOOK MORE INTO
THIS EARLY THIS AFTERNOON. THE NIGHT SHIFT BRIEFED ME ABOUT THE
DIFFERENCES THE MODELS HAVE IN THE TRACK OF THE SURFACE LOW WITH
THE APPROACHING WINTER STORM SYSTEM. THE 00Z/06Z NAM12 STILL HAD A
MUCH MORE NORTHERN TRACK THAN THE OTHER MODELS...BUT I AM HAPPY TO
SEE THAT THE RECENT 12Z NAM12 CAME IN WITH A TRACK MUCH MORE SOUTH
AND SIMILAR TO THE ECMWF AND GFS. HOPEFULLY THE OTHER 12Z MODEL
RUNS WILL FINALLY FIND SOME CONSENSUS...ESPECIALLY THE GEM...WHICH
IS THE OTHER OUTLIER DUE TO ITS MORE SOUTHERN TRACK.
PREV DISCUSSION... /ISSUED 640 AM CDT SUN MAR 17 2013/
AVIATION...12Z TAFS.
VFR UNTIL ABOUT 03Z WHEN MVFR CIGS/VSBYS IN LIGHT SNOW BEGIN TO
SPREAD ACROSS THE TERMINALS FROM W TO E. THIS IS IN RESPONSE TO
THE LARGE LOW PRESSURE SYSTEM THAT WILL MOVE OVER MN MONDAY.
PREV DISCUSSION... /ISSUED 341 AM CDT SUN MAR 17 2013/
SHORT TERM...
TODAY THROUGH MONDAY AFTERNOON...
POTENT WINTER SYSTEM EXPECTED TO IMPACT THE NORTHLAND BEGINNING
TONIGHT AND LASTING THROUGH THE DAY MONDAY.
MAIN CONCERNS IN THE SHORT TERM ARE FOCUSED AROUND ACCUMULATING
SNOW...LOCALLY HEAVY AMOUNTS POSSIBLE...BLOWING SNOW AND GUSTY
WINDS.
A WINTER WEATHER ADVISORY IS IN EFFECT FOR THE ENTIRE NORTHLAND
FROM LATE THIS EVENING THROUGH MONDAY NIGHT.
HIGH PRESSURE CURRENTLY SITUATED OVER FAR NE MN/WRN ONTARIO IS
ALLOWING FOR MOSTLY CLEAR SKIES AND VERY COLD TEMPERATURES ACROSS
THE REGION THIS MORNING. A FEW LOCATIONS IN NE MN HAVE DROPPED
BELOW -20 F...WITH MOST AREAS SEEING WIDESPREAD 0 TO -10 DEG
READINGS. TEMPS SHOULD REBOUND RATHER QUICKLY WITH A HIGH SUN
ANGLE AND A RETURN SOUTHERLY FLOW ON THE WEST SIDE OF THE HIGH AS
IT MOVES EWD THROUGH THE GREAT LAKES REGION. HIGHS TODAY WILL TOP
OUT IN THE 20S.
THIS AFTERNOON...A ROBUST SFC LOW WILL DEVELOP IN THE FRONT RANGE
OF THE NRN ROCKIES AND MOVE EWD INTO THE WRN DAKOTAS. AHEAD OF
THIS SYSTEM...STRONG WAA AND MOISTURE TRANSPORT WILL OCCUR WITH
THE HELP OF A ROBUST LLJ...APPROX 40-50 KT AT 2-3K FT. MOST OF THE
FORCING FOR THIS SYSTEM WILL COME FROM MESOSCALE PROCESSES...AS
THE SYNOPTIC DYNAMICS WILL BE LIMITED. THE COMBINATION OF STRONG
ISENTROPIC LIFT...WAA...AND MODEST MID LEVEL F-GEN WILL ALLOW A
WELL-DEFINED AREA OF ENHANCED SNOW TO DEVELOP ON THE LEADING EDGE
OF THE LOW PRESSURE SYSTEM. THE TRACK OF THE LOW WILL BE CRITICAL
IN DETERMINING WHERE THE HIGHEST SNOW AMTS SET UP. IN THE PAST FEW
DAYS...MODELS HAVE BEEN TRENDING THE TRACK FURTHER NWD ACROSS FAR
NERN MN. HOWEVER...THE PAST COUPLE RUNS OF THE GEM AND ECMWF HAVE
TRENDED BACK TO THE SOUTH. THIS WOULD PLACE A GOOD PORTION OF NERN
MN IN THE FAVORABLE AREA OF THE DEFORMATION ZONE AS THE LOW MOVES
E/NEWD. THE HEAVIEST SNOW RATES WILL LIKELY BE SEEN WITH THE
INITIAL BAND/AREA OF SNOW SUNDAY NIGHT/MONDAY MORNING. THERE IS
SOME INDICATION OF A DRY SLOT WRAPPING AROUND AND PUSHING IN FROM
THE SW MON AFTERNOON...WHICH COULD LIMIT THE AMT OF SNOW SOUTH OF
HIGHWAY 2 IN MN AND AREAS TO THE EAST. THE MOST FAVORABLE AREA OF
HEAVY SNOW WILL BE FROM THE IRON RANGE NWD...DUE TO A PROLONGED
PERIOD IN THE DEFORMATION ZONE...AND ALONG THE ELEVATED TERRAIN OF
THE ARROWHEAD FROM TWO HARBORS NWD...DUE TO LAKE/TERRAIN
ENHANCEMENT. MOST AREAS TO THE SOUTH WILL LIKELY SEE 3-5
INCHES...WITH CLOSER TO 4-7 INCHES ACROSS THE NORTH AND ALONG THE
NORTH SHORE. THIS IS AN INITIAL ASSESSMENT...AND
MORNING/AFTERNOON MODEL GUIDANCE WILL SHED MORE LIGHT ON POTENTIAL
SNOW AMOUNTS. HIGHER AMTS NOT OF THE QUESTION...AND UPGRADES TO
WINTER STORM WARNINGS ARE POSSIBLE.
THE OTHER CONCERN WITH THIS SYSTEM WILL BE THE GUSTY W/NW WINDS
AND AREAS OF BLOWING SNOW...CAUSING REDUCED VSBYS AND DANGEROUS
TRAVEL CONDITIONS. A TIGHT PRESSURE GRADIENT ON THE WRN SIDE OF
THE DEPARTING LOW MON AFTERNOON WILL PRODUCE GUSTS UP TO 30 MPH AT
TIMES. LOCALLY HIGHER GUSTS WILL BE POSSIBLE...AND POTENTIALLY
PRODUCE NEAR WHITE-OUT CONDITIONS...ESPECIALLY FROM LEECH LAKE TO
LAKE MILLE LACS AND AROUND THE TWIN PORTS AREA WHERE HIGHER GUSTS
ARE LIKELY.
LONG TERM...
MONDAY NIGHT THROUGH SATURDAY...
THE VERTICALLY STACKED SYSTEM MOVES OVER NORTHERN LAKE SUPERIOR
BY 12Z TUESDAY. WILL CONTINUE TO SEE LIGHT SNOW IN THE CAA PATTERN
AND EMBEDDED SHORT WAVE ENERGY ROTATING AROUND THE LOW MONDAY
NIGHT. AS THIS SYSTEM SLOWLY LIFTS TO THE ENE INTO ONTARIO...COLD
AIR WILL CONTINUE TO SURGE INTO THE FA WITH MORE SHORT WAVE
ENERGY. HOWEVER...DRY HIGH PRESSURE IS WORKING INTO THE FA FROM
THE NORTHERN PLAINS. EXPECT THE LIGHT SNOW TO BE LIMITED TO THE
ARROWHEAD AND SOME FLURRIES IN NW WI. DIALED BACK ON THE LES
MENTION AS MODEL DIFFERENCES MAKE IT DIFFICULT TO GO WITH HIGHER
POPS/QPF/SNOW AMOUNTS. LITTLE CHANGE TO THE UPPER LEVEL PATTERN
WITH A WNW FLOW AND HIGH PRESSURE AT THE SFC. ONLY MENTION OF
LIGHT SNOW WILL BE ALONG THE SOUTH SHORE OF LS OVER ASHLAND AND
IRON COUNTIES THROUGH THURSDAY. QUIET WEATHER THURSDAY NIGHT
THROUGH SATURDAY.
&&
.POINT TEMPS/POPS...
DLH 21 19 27 5 / 0 90 90 20
INL 21 15 24 -1 / 10 100 90 20
BRD 23 21 24 2 / 10 90 70 10
HYR 25 17 29 4 / 0 80 90 20
ASX 25 18 32 10 / 0 80 90 50
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY FROM 7 AM MONDAY TO 5 AM CDT TUESDAY FOR
MNZ012-020-021.
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO MIDNIGHT CDT
MONDAY NIGHT FOR MNZ010-018-025-026-033>036.
WINTER WEATHER ADVISORY FROM 4 AM MONDAY TO MIDNIGHT CDT MONDAY
NIGHT FOR MNZ011-019-037-038.
WI...WINTER WEATHER ADVISORY FROM 4 AM MONDAY TO MIDNIGHT CDT MONDAY
NIGHT FOR WIZ001-006-007.
WINTER WEATHER ADVISORY FROM 7 AM MONDAY TO MIDNIGHT CDT MONDAY
NIGHT FOR WIZ002>004-008-009.
&&
$$
SHORT TERM...GROCHOCINSKI
LONG TERM....DAP
AVIATION...DAP
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
121 PM CDT SUN MAR 17 2013
.SYNOPSIS...
ISSUED AT 247 AM CDT SUN MAR 17 2013
IN THE ANALYSIS OF THE 06Z MSL PLOT...LOW PRESSURE WAS CENTERED OVER
SOUTHWEST MONTANA WITH A WARM FRONT DRAPED THROUGH CENTRAL WYOMING
TO EASTERN COLORADO. ALSO...A COLD FRONT STRETCHED FROM THE LOW
THROUGH EASTERN BRITISH COLUMBIA TO THE GULF OF ALASKA.
OTHERWISE...HIGH PRESSURE DOMINATED THE SCENE IN THE WESTERN GREAT
LAKES AND THE NORTHERN PLAINS NEAR THE CANADIAN BORDER.
&&
.UPDATE...
ISSUED AT 1017 AM CDT SUN MAR 17 2013
FORECAST HAS BEEN UPDATED TO SLOW THE TIMING OF RAIN SHOWERS INTO
THE PANHANDLE UNTIL EARLY AFTERNOON AND TO EXTEND THE COVERAGE OF
FREEZING DRIZZLE FOR ANOTHER SEVERAL HOURS IN THE COUNTIES
SURROUNDING THE HIGHWAY 83 CORRIDOR.
AT 15Z...THE WARM FRONT REMAINS OUT ALONG THE FRONT RANGE OF THE
ROCKIES...WITH THE COLD FRONT OUT OVER NORTHWEST WYOMING AND
IDAHO. AS THE PRESSURE GRADIENT TIGHTENS AHEAD OF THE
SYSTEM...WINDS HAVE BEEN INCREASING ACROSS THE LOCAL AREA. THERE
ARE SOME WEAK AND VERY SCATTERED RADAR ECHOES BEING PICKED UP
OVER THE PANHANDLE AHEAD OF THE WARM FRONT...BUT DON/T EXPECT ANY
MEASURABLE RAINFALL UNTIL THE FRONT GETS CLOSER AFTER 18Z.
ALSO...WITH THE STRATUS HANGING IN...TEMPERATURES HAVE BEEN SLOW
TO WARM OVER THE EASTERN 2/3RDS OF THE FORECAST AREA...WITH MOST
OF THESE AREAS REMAINING BELOW FREEZING. ALTHOUGH RADAR IS NOT
SHOWING MUCH...AND ASOS/AWOS OBSERVATIONS ARE NOT PICKING UP ON
THE DRIZZLE...BELIEVE THE LOWERED VISIBILITIES IS WHERE THE
FREEZING DRIZZLE IS OCCURRING...ALTHOUGH IT IS VERY LIGHT. IR
SATELLITE ALSO SHOWS CLOUD TOPS WARMER THAN -10C SO ANYTHING
OCCURRING WOULD BE DRIZZLE. AS WINDS CONTINUE TO PICK UP...WOULD
EXPECT THE STRATUS TO BEGIN BREAKING UP YET THIS MORNING AND THE
DRIZZLE COME TO AN END.
WIND ADVISORY LOOKING ON TRACK...AS WINDS SHOULD CONTINUE TO PICK
UP INTO THE AFTERNOON.WITH THE RAP INDICATING 850MB WINDS AT 55KTS
THIS AFTERNOON OVER NORTH CENTRAL NEBRASKA...CONTINUE TO THINK
GUSTS TO 45 MPH ARE LIKELY.
UPDATE ISSUED AT 640 AM CDT SUN MAR 17 2013
NORTH PLATTE AND PROBABLY OGALLALA AND IMPERIAL HAVE BEEN PICKING
UP SOME DRIZZLE. WITH TEMPERATURES BELOW FREEZING THROUGH THE
SOUTHWEST...FREEZING DRIZZLE IS NOT OUT OF THE QUESTION THROUGH
ABOUT MID-MORNING.
&&
.SHORT TERM...(TODAY AND MONDAY)
ISSUED AT 247 AM CDT SUN MAR 17 2013
AS THE WARM FRONT MAKES ITS WAY EASTWARD INTO WESTERN NEBRASKA...
AIR IS LIFTED INTO A HYDRO-STATICALLY UNSTABLE ENVIRONMENT AS
INDICATED BY FOLDING IN A CROSS-SECTION OF THETA-E. A LOOK AT
CONVECTIVE PARAMETERS INDICATES SOME INSTABILITY WITH PRECIPITABLE
WATER VALUES APPROACHING 0.5 INCH. FROM THAT...IT APPEARS THAT THERE
WILL BE AT LEAST ISOLATED THUNDERSTORMS EMBEDDED IN THE BROADER AREA
OF SHOWERS. THIS IS REFLECTED FAIRLY WELL IN THE HOURLY
PRECIPITATION SHOWN BY THE RAP13 SHORT RANGE MODEL AND IN THE GFS
OUTPUT AND EVEN IN THE GEM REGIONAL AND EVEN THE NORTHERN HEMISPHERE
GEM. THE RESULT IS THAT WE HAVE FAIRLY HIGH CONFIDENCE THAT MUCH OF
CENTRAL AND WESTERN NEBRASKA WILL HAVE AT LEAST SCATTERED SHOWERS
THROUGHOUT THE AREA WITH ISOLATED THUNDERSTORMS THIS AFTERNOON
THROUGH LATE THIS EVENING IN SOUTHWEST NEBRASKA. THE COLD FRONT
COMING ACROSS LATE THIS EVENING WILL BRING A QUICK END TO ANY
PRECIPITATION SHORTLY AFTER 06Z.
.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 247 AM CDT SUN MAR 17 2013
MAINLY DRY CONDITIONS WITH NORTHWEST FLOW ALOFT TO START THE WEEK
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. GUSTY NORTHWEST WINDS
ARE EXPECTED IN THE WAKE OF THE SUNDAY NIGHT SYSTEM ON MONDAY.
GOOD MIXING COULD YIELD WIND SPEEDS NEAR WIND ADVISORY. OTHERWISE AN
ARCTIC FRONTAL BOUNDARY WILL OSCILLATE BACK AND FORTH FROM
NORTHEAST TO SOUTHWEST ACROSS THE AREA THROUGH MIDWEEK. THIS FRONT
WILL KEEP THE NORTHEAST SECTIONS OF THE AREA AROUND ONEILL QUITE
CHILLY...WITH TEMPERATURES MOSTLY BELOW NORMAL FOR THIS TIME OF
YEAR. FARTHER SOUTHWEST ACROSS WESTERN AND SOUTHWEST
NEBRASKA...SOMEWHAT WARMER CONDITIONS ARE EXPECTED...WITH
TEMPERATURES RIGHT AROUND NORMAL. ALL AREAS WILL BE BELOW AVERAGE
TEMPERATURE WISE BY THE END OF THE WEEK...AS THE ARCTIC FRONT
MOVES SOUTH IN RESPONSE TO STRONG SFC HIGH PRESSURE NOSING SOUTH
INTO THE NORTHERN PLAINS.
FOLLOWED THE GFS ENSEMBLE MEAN IN REGARDS TO PRECIP CHANCES...AND 30
TO 40 PERCENT SEEMS REASONABLE WEDNESDAY NIGHT THROUGH FRIDAY AS A
SIGNIFICANT DISTURBANCE DROPS SOUTHEAST INTO THE AREA. OPERATIONAL
MODELS HAVE BEEN STRUGGLING ON HOW TO HANDLE THIS ENERGY DROPPING
SOUTHEAST INTO THE AREA. THIS IS LIKELY DUE TO A BLOCKY TYPE UPPER
PATTERN. FELT THE GFS ENSEMBLE MEAN WAS THE WAY TO LEAN AT THIS
POINT...AND FOR WHAT IT/S WORTH...THE MEAN REPRESENTS THE
OPERATIONAL GFS OUTPUT BETTER THAN THE ECMWF. THIS WOULD BE A
WETTER SOLUTION FOR US...AND THE PRECIPITATION WOULD BE MOSTLY IN
THE FORM OF SNOW DUE TO COLD AIR IN PLACE. STAY TUNED.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 120 PM CDT SUN MAR 17 2013
FORECAST CONCERNS OVER THE NEXT 24 HOURS DEAL WITH
CEILINGS...SHOWER CHANCES...AND WINDS AS PASSAGES OF BOTH WARM AND
COLD FRONTS WILL OCCUR. MVFR CEILINGS WILL IMPROVE THIS AFTERNOON
AS THE STRATUS BREAKS UP. BREEZY TO STRONG SOUTHERLY WINDS ARE
ONGOING ACROSS WESTERN AND NORTH CENTRAL NEBRASKA EARLY SUNDAY
AFTERNOON. WINDS ARE EXPECTED TO INCREASE FURTHER YET THIS
AFTERNOON...THEN SWITCH TO THW SOUTHWEST AS THE WARM FRONT MOVES
THROUGH THIS EVENING. AHEAD OF THE FRONT...SCATTERED RAIN SHOWERS
AND A FEW EMBEDDED THUNDERSTORMS WILL OCCUR ACROSS THE AREA. WITH
THE NATURE OF JUST ISOLATED THUNDER...DON/T HAVE THE CONFIDENCE IN
THUNDER OCCURING AT EITHER KVTN OR KLBF SO HAVE NOT INCLUDED THE
TS MENTION IN THE FORECAST AND WILL MONITOR AND UPDATE THE
FORECAST IF NEEDED. THE COLD FRONT WILL MOVE THROUGH LATE THIS
EVENING AND OVERNIGHT TO SWITCH WINDS TO THE NORTHWEST. DO EXPECT
STRONG WINDS AGAIN ON MONDAY BEHIND THE FRONT WITH GUSTS BETWEEN
25 AND 35 KTS.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 8 PM CDT /7 PM MDT/ THIS EVENING FOR NEZ005-
006-008-009-023>025-094.
WIND ADVISORY UNTIL 10 PM MDT THIS EVENING FOR NEZ004-022-056.
&&
$$
SYNOPSIS...SPRINGER
SHORT TERM...SPRINGER
LONG TERM...TAYLOR
AVIATION...BROOKS
AREA FORECAST DISCUSSION...UPDATED
NWS OMAHA/VALLEY NE
1246 PM CDT SUN MAR 17 2013
.UPDATE...
&&
.AVIATION...18Z TAFS FOR KOMA...KLNK...KOFK.
MAIN CONCERN IS TIMING PCPN/LOW CIGS LATER TONIGHT. AN UPPER
DISTURBANCE IS EXPECTED TO MOVE ACROSS THE DAKOTAS TONIGHT WITH
ATTENDANT COLD FRONT SWEEPING INTO THE CNTRL PLAINS. AT THIS POINT
ANTICIPATE MVFR CONDITIONS WILL GRADUALLY EXPAND SWD OVER ERN NEB
EARLY THIS EVENING. AS OF NOW BELIEVE BEST CHANCE FOR -RA/SN MIX
OCCURRING GENERALLY BTWN 18 /05Z-11Z...THUS HAVE INCLUDED PROB30
GROUPS AT ALL TERMINALS. CROSS WIND THREAT AT THIS TIME APPEARS
MINIMAL DURING FRONTAL PASSAGE.
DEE
PREV DISCUSSION... /ISSUED 328 AM CDT SUN MAR 17 2013/
DISCUSSION...
THE CHANCE FOR RAIN AND SNOW TONIGHT THEN WINDS BEHIND COLD FRONT
MONDAY ARE THE PRIMARY FORECAST CONCERNS.
A COUPLE OF AREAS OF PRECIPITATION WERE IN OR NEAR OUR CWA THIS
MORNING. LIGHT SNOW MOVED FROM NORTH CENTRAL INTO NORTHEAST NEBRASKA
DURING THE LATE EVENING...DROPPING A DUSTING TO A HALF INCH OF SNOW
FOR SOME OF OUR NORTHERN AREAS. THIS SEEMED TO BE TIED TO 90-120KT
300MB JET STRETCHING FROM NORTHERN NEBRASKA INTO THE GREAT LAKES.
WITH THAT JET SHIFTING EAST THIS MORNING...THINK ANY LINGERING SNOW
SHOWERS WILL BE SHORT-LIVED AFTER SUNRISE. SHORT RANGE MODELS RAP
AND HRRR CONCUR. THE SECOND AREA OF PRECIPITATION WAS STAYING MOSTLY
SOUTH OF THE CWA ACROSS NORTHERN KANSAS...AND LOOKED TO BE CAUSED BY
MID LEVEL WARM ADVECTION AHEAD OF 700MB SHORTWAVE MIGRATING EAST
THROUGH KANSAS. A FEW RADAR RETURNS MOVED ACROSS THE SOUTHEAST
NEBRASKA BORDER...BUT TRENDS HAVE BEEN TO CONCENTRATE PRECIP JUST
SOUTH OF OUR AREA. SO ONLY SMALL CHANCES EARLY TODAY THERE...WITH
LIGHT SNOW THE MAIN PRECIP TYPE.
ATTENTION THEN TURNS TO STRONG MID LEVEL SHORTWAVE NOW DIVING
THROUGH WASHINGTON AND OREGON INTO IDAHO. THIS FEATURE WILL RACE
EAST AND STRENGTHEN TODAY...REACHING THE WESTERN DAKOTAS BY
00Z...WITH AXIS OF MID LEVEL TROUGH SWINGING THROUGH OUR AREA MONDAY
MORNING. STRONG SURFACE LOW WILL DEVELOP IN THE NORTHERN HIGH PLAINS
THROUGH THE DAY...THEN ROTATE THROUGH THE DAKOTAS OVERNIGHT WHILE
DRIVING A COLD FRONT THROUGH NEBRASKA AND WESTERN IOWA BY SUNRISE
MONDAY. SOUTHEAST TO SOUTH LOW LEVEL FLOW WILL DEVELOP IN OUR AREA
TODAY IN RESPONSE TO LOWERING PRESSURES TO OUR NORTHWEST...AND WILL
PUSH TEMPERATURES TOWARD 40 THIS AFTERNOON. MID LEVEL THETA-E
INCREASE IN DIFFLUENT FLOW REGIME AHEAD OF TROUGH WILL PROVIDE
SUFFICIENT MOISTURE/LIFT FOR PRECIPITATION AS EARLY AS THIS
AFTERNOON IN CENTRAL AND PERHAPS NORTHEAST NEBRASKA. BUT BETTER
CHANCES COME OVERNIGHT AHEAD OF SURFACE COLD FRONT UNDER CORE OF MID
LEVEL JET SEGMENT. HAVE KEPT PRECIPITATION CHANCES RELATIVELY
HIGH...WITH BEST CHANCES ACROSS THE NORTH NEARER BETTER COMBINATION
OF LIFT/MOISTURE.
PRECIPITATION TYPE CONTINUES TO BE AN ISSUE AS SURFACE LAYER REMAINS
ABOVE FREEZING UNTIL COLD FRONT ARRIVES. MODEL DEPICTIONS OF LAYER
TEMPERATURE PROFILES ARE NOT CONSISTENT WITH EACH OTHER...AND
TEMPERATURE TRENDS WITHIN THE SAME MODEL SPORADICALLY MOVE THERMAL
PROFILE FROM JUST ABOVE TO JUST BELOW FREEZING AND BACK AGAIN WITH
TIME. THIS IS LIKELY DUE TO DYNAMIC COOLING EFFECTS GIVEN VIGOROUS
BUT SMALL AREAS OF LIFT UNDER FAST FLOW. SO A VARIETY OF WEATHER
TYPES ARE POSSIBLE FROM TIME TO TIME OVERNIGHT...BUT WILL FOCUS THIS
FORECAST ON TIMING OF PREDOMINANT WEATHER TYPE CHANGING FROM MAINLY
RAIN TO MAINLY SNOW...AND LET POTENTIAL SNOW AMOUNTS FALL OUT OF
THAT THINKING.
THERMAL PROFILES WILL SUPPORT RAIN FROM LATE THIS AFTERNOON THROUGH
MID EVENING...WITH THICKNESS PROGS SUGGESTING A TRANSITION TOWARD
SNOW IN OUR NORTHWEST BY 03Z. THAT TREND WILL QUICKLY SWING EAST AND
SOUTHEAST THROUGH 06Z...WITH MAINLY SNOW EXPECTED IN OUR SOUTH AFTER
09Z. BETTER COOLING REGIME IS EXPECTED ACROSS OUR NORTH...SO HIGHER
POTENTIAL SNOW TOTALS THERE. HOWEVER...STRONG LIFT NEAR AND
NORTH/NORTHEAST OF THE OMAHA METRO AREA AROUND 06Z MAY END UP BEING
THE MAIN SNOW ZONE WITH THIS SYSTEM. AN ENSEMBLE APPROACH TO SNOW
AMOUNT FORECAST SUGGESTS 1 TO 2 INCHES WILL BE COMMON FROM NORTHEAST
NEBRASKA INTO WEST CENTRAL IOWA. THIS COMBINES STRAIGHT MODEL
OUTPUT...COBB CALCULATIONS OF SEVERAL MODELS...AND A GARCIA
MANIPULATION OF MIXING RATIOS TAKING INTO ACCOUNT 6 HOUR PERIOD OF
PRECIPITATION AND A TRANSITION FROM RAIN TO SNOW OCCURRING NEAR THE
MIDWAY POINT OF THE PRECIP.
FAST-MOVING SYSTEM SHOULD TAKE MOST PRECIPITATION EAST OF OUR WESTERN
IOWA COUNTIES BY 12Z MONDAY. STRONG WINDS WILL FOLLOW DURING THE DAY
AS UNIDIRECTIONAL NORTHWEST FLOW AND STRONG COLD ADVECTION POINT TO
EFFECTIVE TRANSFER OF MOMENTUM IN THE BOUNDARY LAYER. FORECAST
SOUNDINGS STILL SHOW THE POTENTIAL FOR 40MPH WIND GUSTS ON MONDAY.
AND AM NOT EXPECTING A LOT OF WARMING MONDAY GIVEN COLD ADVECTION
DESPITE CLEARING SKIES. HAVE HIGHS GENERALLY IN THE 30S NORTH TO
LOWER 40S SOUTH.
THE REST OF THE WEEK STILL LOOKS TO BE COOL. TUESDAY MAY BE THE
WARMEST...OR LEAST COOL...DAY OF THE WEEK WHERE A RELATIVELY MILD
START AND SUNSHINE ALLOW TEMPS TO REBOUND INTO 40S. OTHERWISE
NORTHWEST MID LEVEL FLOW AT MID WEEK WILL BE REPLACED BY WAVE/LOW
APPROACHING FOR THE END OF THE WEEK INTO THE WEEKEND. OFF-AND-ON
PRECIPITATION CHANCES WILL RESULT BEGINNING WEDNESDAY NIGHT...WITH
CLOUDS AND LITTLE IN THE WAY OF WARM/COLD ADVECTION SUGGESTING
TEMPERATURES WILL BE RANGE-BOUND IN THE 20S FOR LOWS AND 30S OR
LOWER 40S FOR HIGHS.
DERGAN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
99/99
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
435 PM EDT SUN MAR 17 2013
.SYNOPSIS...
A WEAK COLD FRONT ALONG THE NORTH CAROLINA...SOUTH CAROLINA BORDER
WILL SLOWLY MEANDER ACROSS THE FORECAST AREA THIS EVENING. MEANWHILE
A SECONDARY COLD FRONT WILL SWEEP ACROSS THE DEEP SOUTH ON TUESDAY
ALLOWING COLDER AIR TO FILTER IN BEHIND IT ON WEDNESDAY. COOL HIGH PRESSURE
WILL REMAIN ACROSS THE AREA INTO FRIDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
430 PM UPDATE...REVISED TEMP/DEWPT TRENDS A BIT TO BETTER REFLECT
FRONTAL POSITIONING. FRONTAL BOUNDARY STILL MAKING SLOW SWD PROGRESS
ON TCLT IMGY AND COOLING TREND LIKELY HAS ALREADY STARTED NORTH OF
THE BDY...WHILE SITES WEST/SOUTH OF IT WILL REMAIN FAIRLY STEADY FOR
ANOTHER HR OR TWO. DELAYED SCHC POPS IN NRN MTNS UNTIL EARLY EVENING
AS CONVECTIVE TRENDS ON SATELLITE IMGY NOT ESPECIALLY IMPRESSIVE
THERE DESPITE HAVING A SMALL AMOUNT OF MUCAPE SHOWN ON SPC
MESOANALYSIS.
AS OF 300 PM SUN...THE TCLT RADAR SHOWS THE NASCENT WEDGE BOUNDARY
PUSHING SW ACROSS THE PIEDMONT INTO THE CHARLOTTE METRO
AREA...RUNNING OUT AHEAD OF THE LOWER CLOUDS WHICH ARE THINNING
ACROSS THE NW PIEDMONT. THE BOUNDARY MIGHT FIND IT DIFFICULT MOVING
MUCH FARTHER INTO AN AIR MASS THAT IS BEING HEATED FROM ABOVE... SO
EXPECT IT TO STALL BEFORE RESUMING ITS SW DRIFT AROUND SUNSET.
THAT WILL BEGIN A COLD AIR DAMMING EVENT AS A STRENGTHENING SFC HIGH
SLIDES INTO POSITION OVER NEW ENGLAND THIS EVENING AND LOW PRESSURE
MOVES ACROSS THE MID MS VALLEY. THE SET UP IS SOMEWHAT CLASSIC WITH
A CONFLUENT UPPER FLOW OVER THE NORTHEAST AND DEVELOPING LOW LEVEL
UPGLIDE AND WARM ADVECTION THIS EVENING. IT MIGHT TAKE A WHILE FOR
ANY SORT OF DIABATIC EFFECTS TO KICK IN. THE MODEL GUIDANCE HAS NOT
BEEN VERIFYING PARTICULARLY WELL WITH DEVELOPING PRECIP INTO THE
FOOTHILLS AND PIEDMONT THIS AFTERNOON AND THINK THAT IT WILL NOT BE
UNTIL BETTER UPGLIDE/UPSLOPE DEVELOPS LATER THIS EVENING BEFORE WE
WILL GET ANY APPRECIABLE PRECIP RESPONSE...SO THE ONSET OF THE
CHANCE POP WAS DELAYED. IT SHOULD EVENTUALLY CATCH UP BEFORE
SUNRISE...BUT DID NOT GO INTO THE LIKELY CATEGORY FOR NOW BECAUSE
THE BETTER FORCING REMAINS TO OUR NORTH. TEMPS WILL COOL OFF SLOWLY
WITH THE INCREASE IN CLOUDS. THE LATEST GUIDANCE KEEPS THE ENTIRE
AREA ABOVE FREEZING...MITIGATING ANY POTENTIAL PROBLEMS NEAR THE
BLUE RIDGE.
ON MONDAY...WE SHOULD HAVE A WELL DEVELOPED COOL POOL ENTRENCHED
ACROSS THE REGION E OF THE BLUE RIDGE THAT SHOULD HOLD ON THROUGH
THE BETTER PART OF THE REGION THROUGH THE DAY GIVEN THE WARM
ADVECTION SEEN AT 850MB OVER THE TOP OF IT. THINK THE NAM HAS THE
BETTER DEPICTION OF ONLY THE SRN/SW FRINGE MANAGING TO MAKE IT INTO
THE WARMER AIR. FORCING WILL INCREASE TO THE WEST AND SOUTH DURING
THE AFTERNOON. PREFRONTAL SHOWERS AND STORMS MAY REACH THE WRN SIDE
OF THE NC MTNS BY THE END OF THE PERIOD SO PRECIP CHANCES GRADUALLY
RISE TO CATEGORICAL BY THE END OF THE DAY. TO THE SOUTH...THE MODELS
SHOW EXCELLENT LOW LEVEL FORCING ALONG THE WEDGE BOUNDARY ACROSS NE
GEORGIA AND THE LAKELANDS...SO PRECIP CHANCES ALSO RAMP UP THERE.
TEMPS FAVOR THE COOLER MET GUIDANCE.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 200 PM SUNDAY...THE DETAILS OF THE EVOLVING PRECIPITATION
EVENT MONDAY NIGHT AND EARLY TUESDAY REMAIN A BIT SKETCHY. THE NAM
ACTUALLY DEPICTS TWO WAVES OF PRECIPITATION MOVING ACROSS THE AREA
DURING THIS PERIOD...THE FIRST BEING THE WARM CONVEYOR BELT/PRE-
FRONTAL WAVE...THE SECOND BEING ALONG AND IMMEDIATELY BEHIND THE
FRONT EARLY TUESDAY...AS A STRONG UPPER JET AXIS/ASSOCIATED VORT MAX
LIFTS INTO THE TENN/OHIO VALLEY. IT IS INTERESTING THAT SOME OF THE
HIGH RES MODELS DEPICT SIMILAR EVOLUTION. I THINK IT/S POSSIBLE IF
NOT LIKELY THAT A NARROW BAND OF SHOWERS WILL DEVELOP ALONG THE
FRONT ACROSS THE TENN VALLEY MONDAY EVENING...BUT WITH STRONGLY
VEERING PRE-FRONTAL FLOW...I CAN/T SEE THIS MAKING A LOT OF HEADWAY
EAST OF THE MTNS. THEREFORE...WE WILL CONTINUE TO DEPICT THE HIGHEST
POPS DURING THE EVENING...BUT WILL HOLD ON TO HIGH CHANCE/LOW LIKELY
POPS ACROSS THE WESTERN MTNS AFTER MIDNIGHT. THERE WILL BE A WANING
MARGINAL SEVERE WEATHER THREAT MONDAY EVENING...MAINLY ACROSS THE
FAR WESTERN MTNS WITH ANY WEAKENING CONVECTIVE FRONTAL BAND...AND
PERHAPS OVER THE FAR SOUTHERN ZONES...WHERE A COUPLE OF DISCRETE
CELLS CANNOT BE RULED OUT IN THE VICINITY OF THE LINGERING CAD
BOUNDARY.
CONDITIONS SHOULD IMPROVE RAPIDLY DURING THE DAY TUESDAY...WITH A
WARM AND SUNNY BUT BREEZY AFTERNOON EXPECTED. LOWERING THICKNESS
VALUES IN RESPONSE TO DEVELOPING EASTERN CONUS LONG WAVE TROUGH WILL
RESULT IN COOLER WEATHER FOR WEDNESDAY...WITH MAXES EXPECTED TO
AVERAGE A CATEGORY OR TWO BELOW CLIMO. WEDNESDAY WILL ALSO BE
ANOTHER VERY BREEZY DAY...IN RESPONSE TO AN APPROACHING CLIPPER.
GUSTS AS HIGH AS 40 MPH WILL BE POSSIBLE IN MOST AREAS DURING THE
AFTERNOON.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 230 PM SUNDAY...CONFIDENCE IN THE MEDIUM RANGE IS MUCH LOWER
THAN NORMAL...AS A RATHER COMPLEX LARGE SCALE PATTERN TAKE SHAPE.
THE MOST PROMINENT FEATURE WILL BE THE VERY STRONG POLAR VORTEX THAT
BECOMES ESTABLISHED ACROSS THE NORTHEAST CONUS BY DAY FOUR. THIS
DOES PROVIDE REASONABLE CONFIDENCE THAT TEMPERATURES OVER OUR AREA
WILL BE BELOW NORMAL...IN FACT WELL BELOW NORMAL THROUGH THE LATTER
PART OF THE WEEK. HOWEVER...THE MAJOR GLOBAL MODELS DISAGREE WIDELY
IN THEIR HANDLING OF INDIVIDUAL SHORT WAVE TROUGHS MOVING OUT OF THE
PACIFIC NORTHWEST DURING THE LATTER HALF OF THE PERIOD. IN FACT...BY
DAY SIX...THE NAM AND ECMWF ARE QUITE OUT OF PHASE...WITH A
REINFORCEMENT OF AN EASTERN TROUGH DEPICTED IN THE GFS...AND A
CENTRAL/SOUTHERN ROCKIES TROUGH ADVERTISED IN THE ECMWF. THESE
FACTORS CREATE QUITE THE CONUNDRUM IN TERMS OF THE PRECIP FORECAST
DURING THE LATTER HALF OF THE MEDIUM RANGE. AS SUCH...WE DO NOT FEEL
COMFORTABLE WITH ADVERTISING POPS ANY HIGHER THAN 30 PERCENT DURING
THE PERIOD...NOR DO WE FEEL COMFORTABLE WITH ANYTHING LESS THAN 20
PERCENT. SLIGHT/LOW CHANCE POPS WILL BE ADVERTISED DURING EVERY
PERIOD FROM THURSDAY NIGHT ON. DESPITE THE UNSEASONABLY COOL AIR...
TEMPS ARE EXPECTED TO BE MORE WARM ENOUGH TO SUPPORT MOSTLY RAIN IN
THE PIEDMONT...BUT PERIODS OF SNOW WILL BE POSSIBLE OVER PORTIONS OF
THE MTNS.
&&
.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
21Z KCLT UPDATE...FRONT HAS SLOWLY MOVED SOUTH OF THE AIRFIELD AT A
STEADY RATE AND I HAVE FAIRLY HIGH CONFIDENCE WINDS WILL REMAIN NE
TO ENE...THAT IS...THE FRONT WILL NOT PUSH BACK NORTH. COLD AIR
OUTRAN THE CLOUDS AND SO THERE IS AN AREA FREE OF LOW CLOUD BETWEEN
THE WSHFT LINE AND THE MORE WEDGELIKE MVFR DECK OVER NRN NC. THIS
AND LLVL COLD ADVECTION ALLOWED FOR MIXING WHICH CAUSED WINDS TO
GUST. NOW THAT CIRRUS ARE FILLING IN OVERHEAD GUSTING MAY DIMINISH.
RAP GUIDANCE BRINGS MVFR IN BY 01Z BUT THIS MAY BE OVERDONE. KEPT
SCT MVFR LEVEL CLOUDS IN FCST AT 00Z...BUT LOWERED THEM TO 020 IN
LIGHT OF RAP AND UPSTREAM OBS.
AT KCLT...WITH SUNSET...THERE SHOULD BE NOTHING TO STOP THE SHALLOW
COOLER AIR FROM MOVING DOWN FROM THE NE. ONCE THE NE FLOW IS
ESTABLISHED...THE WEAK LIFT OVER TOP OF IT DUE TO SW WIND ALOFT WILL
BRING THE LOW CLOUDS OVER THE SRN PIEDMONT...SO CEILING WILL START
TO DROP. MVFR SHOULD HAPPEN IN THE MID TO LATE EVENING AND IFR
DEVELOPING IN THE 07Z TO 09Z TIME FRAME LOOKS LIKE A GOOD BET. VSBY
DOES NOT LOOK LIKE IT WILL DROP MUCH... SO CEILING WAS KEPT ABOVE
006. THE CEILING SHOULD START TO LIFT AROUND 16Z ON MONDAY AS TEMPS
STRUGGLE TO WARM UP.
ELSEWHERE...KHKY HAS SAME CONCERNS AS KCLT...PERHAPS A FEW HOURS
EARLIER. THE SC SITES WILL BE LAST TO SEE A WIND SHIFT OUT OF THE NE
AND DEVELOPING STRATUS...PROBABLY NOT UNTIL A FEW HOURS AFTER
SUNSET. GUIDANCE STILL DOES NOT DEVELOP MUCH PRECIP ALONG THE
FRONT...SO IT WAS LEFT OUT OF THE TAFS. OTHERWISE...LOOKS LIKE
IFR/LOW MVFR CONDITIONS MAINLY DUE TO CEILING WITH A NE WIND UNDER A
COLD AIR DAMMING REGIME THROUGH THE END OF THE TAF PERIOD.
OUTLOOK...COLD AIR DAMMING WEDGE WILL PERSIST ON MONDAY AFTERNOON...
PRODUCING RESTRICTIONS IN CIGS AND -RA. ANOTHER COLD FRONT WILL
CROSS THE AREA FROM THE WEST MONDAY NIGHT/EARLY TUESDAY...
INTRODUCING DRIER AIR AND IMPROVING CONDITIONS FOR TUESDAY. VFR FROM
TUESDAY AFTERNOON ONWARD.
CONFIDENCE TABLE...
20-02Z 02-08Z 08-14Z 14-20Z
KCLT HIGH 94% HIGH 90% MED 79% HIGH 85%
KGSP HIGH 100% HIGH 96% MED 78% HIGH 94%
KAVL HIGH 100% MED 79% MED 76% MED 75%
KHKY HIGH 88% HIGH 96% MED 79% HIGH 92%
KGMU HIGH 100% HIGH 96% MED 78% HIGH 89%
KAND HIGH 100% HIGH 98% HIGH 85% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PAT
NEAR TERM...PM/WIMBERLEY
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...PM/WIMBERLEY
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
354 PM CDT SUN MAR 17 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 351 PM CDT SUN MAR 17 2013
STRONG FORCING PUSHING OUT INTO THE SOUTHWESTERN PORTIONS OF THE
RUSHMORE STATE AND NEBRASKA PANHANDLE. VERY STEEP LAPSE RATES IN
PLACE EVIDENCED BY A FEW LIGHTNING STRIKES ACROSS WESTERN AND NORTH
CENTRAL NEBRASKA DURING THE EARLY AND MID AFTERNOON. AHEAD OF THIS
WAVE AND DEVELOPING LOW PRESSURE...STRONG SOUTHERLY WINDS IN
PLACE...WITH ADVISORY LEVEL WINDS AT TIMES AROUND THE LOWER BRULE
AREA. THESE WINDS SHOULD EASE A BIT GOING INTO THE EARLY EVENING...
WHILE THE MAIN GRADIENT LIFTS NORTH AND EAST WITH THE MAIN CYCLONE
CENTER HEADING TOWARD EXTREME NORTHEAST SOUTH DAKOTA BY LATE EVENING.
SEVERAL BANDS OF SHOWERS IN PROCESS OF DEVELOPING ACROSS THE STATE.
HI RES MODELS...INCLUDING RAP AND SREF...HAVE TRENDED QUICKER WITH
THE PRECIP...WITH MUCH OF THE BAND EAST OF I29 BY 07-08Z...WITH
EXCEPTION OF AREA ACROSS NORTHERN CWA CLOSER TO THE MID LEVEL
CIRCULATION. NATURE OF A VERY TRANSIENT BAND WILL BE LIMITING FACTOR
ON AMOUNTS...AS WILL THE TEMPERATURES ALOFT WHICH FIGURE UP JUST A
BIT TOO WARM FOR ANY SNOW IN THE FAR SOUTHWEST...AND WILL KEEP A MIX
IN THE WORKS FROM JAMES THROUGH LOWER MISSOURI VALLEY. ONLY THE
COOLER AND SLIGHTLY DRIER AIRMASS TO THE EAST...ALONG WITH THE
DYNAMIC COOLING RESULTING FROM CONVECTIVE NATURE TO PRECIPTIATION
AND SHARP LIFT FORCING WILL FORCE PRECIPITATION OVER TO SNOWFALL.
AMOUNTS SOMEWHAT DIFFICULT TO PIN DOWN GIVEN THE CONVECTIVE
NATURE...WITH AMOUNTS EXPECTED TO REFLECT THE AREAL AVERAGE...
GREATEST ACROSS PARTS OF NORTHWEST IOWA INTO SOUTHWEST MINNESOTA.
DEBATE FOR THE DAY WAS WHAT IT MIGHT TAKE TO GET BLIZZARD CONDTIONS
GIVEN THE CERTAINTY OF STRONG WINDS ON LATE SUNDAY NIGHT AND THROUGH
THE DAY MONDAY. CERTAINLY NONE OF THE REMAINING SNOWCOVER WILL
CONTRIBUTE DIRECTLY...AND REALLY ONLY HAVE AROUND A TWO INCH BAND
ACROSS THE NORTHERN TIER ALONG HIGHWAY 14. STRONGEST WINDS WITH
GUSTS UPWARD OF 45 MPH AT TIMES WILL BE FROM EAST CENTRAL SOUTH
DAKOTA THROUGH SOUTHWEST MINNESOTA...SPEEDS TAPERING OFF SLIGHTLY TO
THE SOUTHWEST...BUT BALANCED SOMEWHAT BY A DEEPER MIXING PROFILE.
NOT EXPECTING A GREAT DEAL OF ADDITIONAL SNOW BY MONDAY...WITH ONLY
THE STEEP LOW LEVEL LAPSE RATES IN REACH OF FAVORABLE ICE GROWTH
RANGE SUGGESTING BANDED SHALLOW SNOW SQUALLS... SO CONTRIBUTIONS
HERE WILL BE FAIRLY MINIMAL. WHERE WE GET A COUPLE OF INCHES OVER
EXISTING SNOW/ICE COVER...WILL BE VERY CAPABLE OF SOME DECENT
LOFTING. WHERE NO SNOWCOVER CURRENTLY EXISTS...WILL BE MUCH MORE
DIFFICULT TO OBTAIN ANY TRUE BLIZZARD CONDITIONS...BUT DID ADD IN A
COUPLE MORE COUNTIES TOWARD THE SOUTH IN SOUTHWEST MINNESOTA TOWARD
WHERE SOME HEAVIER SNOWFALL MAY OCCUR. FARTHER SOUTH AND WEST...
NOT EXPECTING ANY WHITEOUT CONDITIONS TO BE WIDESPREAD...BUT THAT IS
NOT SAYING THERE WOULD BE ANY WHITEOUT CONDITIONS...JUST NOT
WIDESPREAD OR LONG LASTING. CAUTION IS NEEDED...EVEN THROUGH THE
ADVISORY AREA. DID NOT POST BLIZZARD WARNING RIGHT OFF TO START...
AS STRONGER WINDS WILL COME IN LATER TONIGHT/EARLY MONDAY IN THE
WARNING AREA...SO PRECEDED WITH A WINTER WEATHER ADVISORY UP TO 09Z
IN THE BLIZZARD AREA FOR THE COMBINATION OF SNOWFALL AND SOME LESSER
POTENTIAL BLOWING SNOW WITH THE PREFRONTAL SOUTH/SOUTHWEST WINDS.
PROBABLY NOT A GREAT DEAL OF ROOM FOR RECOVERY IN TEMPS ON MONDAY
WITH STRONG SURGE OF COLDER AIR WRAPPING IN BEHIND SYSTEM. ONLY THE
MORE MIXED MISSOURI VALLEY WHERE LESS SNOW IS EXPECTED SHOULD SEE
ANY LESS THAN MINIMAL RECOVERY IN TEMPS.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 351 PM CDT SUN MAR 17 2013
THE SYSTEM PULLS OUT OF THE REGION ON MONDAY NIGHT...WITH GUSTY
NORTHWESTERLY WINDS DYING THROUGH THE EVENING AS A SURFACE RIDGE
SLIDES SOUTHWARD INTO THE NORTHERN PLAINS CAUSING THE GRADIENT TO
SLACKEN. TEMPERATURES ARE TRICKY THAT NIGHT...DEPENDENT ON HOW
QUICKLY THE WINDS DIE/WHERE NEW FALLEN SNOW IS IN PLACE/AND HOW MUCH
CLEARING IS REALIZED OVERNIGHT. MODEL RH TIME SECTIONS POINT TOWARD
LOWER CLOUDS CLEARING FROM WEST TO EAST DURING THE EVENING...THOUGH
MID/HIGH CLOUDS INCREASING IN THE WEST LATER AT NIGHT. AT THIS
POINT...WENT WITH LOWS AROUND ZERO ALONG HIGHWAY 14 TO THE LOWER
TEENS THROUGH THE MISSOURI RIVER CORRIDOR.
ANOTHER WEAK SHORTWAVE WILL TRACK ACROSS THE AREA ON TUESDAY...AND
MAY BE JUST ENOUGH MOISTURE AROUND TO KICK OFF A FEW FLURRIES IN OUR
EAST. TEMPERATURES WILL STILL BE MUCH BELOW NORMAL FOR THIS TIME OF
YEAR WITH HIGHS GENERALLY IN THE 20S NORTH TO 30S SOUTH. FARTHER
INTO THE EXTENDED...A BROAD UPPER LEVEL LOW OVER THE EASTERN
PORTIONS OF THE COUNTRY WILL KEEP OUR AREA IN A NORTHWESTERLY UPPER
LEVEL FLOW FOR WEDNESDAY AND EARLY THURSDAY BEFORE THE NEXT
SHORTWAVE BEGINS TO ENCROACH ON THE AREA IN THE LATE THURSDAY TO
FRIDAY TIME FRAME. MODELS CONTINUE TO DIFFER ON HOW THEY HANDLE THIS
SYSTEM...WITH BOTH THE ECMWF AND GEM KEEPING IT FARTHER TO THE
SOUTH..AND THE GFS PERSISTING WITH A MORE NORTHERLY SOLUTION. SOME
CONSENSUS...WEIGHED MORE HEAVILY TO THE MORE SOUTHERLY SOLUTION
WOULD BRING A CHANCE OF LIGHT SNOW TO OUR SOUTHWEST DURING THIS TIME
FRAME. MODELS KEEP MUCH BELOW NORMAL THERMAL PROFILES IN PLACE
ACROSS THE REGION THROUGH NEXT WEEKEND...WITH HIGHS GENERALLY 20S AND
30S...AND LOWS SINGLE DIGITS AND TEENS EARLY ON...TO TEENS AND 20S
LATE IN THE PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1249 PM CDT SUN MAR 17 2013
MANY COMPLEX AVIATION ISSUES FOR THIS TAF ISSUANCE SET. STRONG
WAVE SET TO PUSH OUT OF WYOMING INTO WESTERN SD AND THE NEBRASKA
PANHANDLE AT MIDDAY. FAIRLY SCATTERED PRECIPITATION STARTING TO
DEVELOP IN THE WEST THIS AFTERNOON...EXPECTED TO BECOME MORE
WIDESPREAD WITH INCREASED FORCING. MUCH OF INITIAL PRECIP TO THE
WEST SHOULD FAVOR A LIQUID FORM...BUT AS INTENSITY INCREASES AND
MOVEMENT OF LIFT FORCING SHIFTS TOWARD INTO THE COOLER AND DRIER
AIRMASS TO THE EAST...SHOULD GET A FAIRLY RAPID TRANSITION OVER
TOWARD SNOW...OCCURING BY EARLY EVENING AT KHON...MID EVENING FOR
KFSD...AND LATER FOR KFSD. VERY CONVECTIVE COMPONENT TO DEVELOPING
PRECIP...SO MAY BE HEAVY WITH VISIBILITIES LIKELY EVEN LOWER FOR
SHORT PERIODS OF TIME WITHIN CORE OF SNOW BAND...PERHAPS BRIEFLY
INTO VLIFR.
WINDS OF SECONDARY CONCERN. STRONG SOUTHEAST WINDS WITH GUSTS AT
OR ABOVE 35 KNOTS WEST OF THE JAMES VALLEY TODAY. COULD BE A
PERIOD OF MARGINAL LOW LEVEL WIND SHEAR THIS EVENING WITH PARTIAL
DECOUPLING...BUT STRONGEST WINDS ARE LIKELY TO OCCUR LATER TONIGHT
THROUGH MONDAY BEHIND THE COLD FRONT AND EXITING AREA OF LOW
PRESSURE. MOST LIKELY AREA TO EXPERIENCE ANY SEVERELY REDUCED
VISIBILITY WITH BLOWING SNOW/SNOW SQUALLS WOULD BE NORTH AND EAST
OF THE KFSD TAF SITE...MAINLY KBKX/KMML/KMWM CORRIDOR. /CHAPMAN
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 PM CDT
MONDAY FOR SDZ038-054>056-062-067.
WIND ADVISORY FROM 4 AM TO 7 PM CDT MONDAY FOR SDZ050-052-053-
057>061-063>066-068>071.
WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR SDZ050-052-057-058-
063-064.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM CDT
MONDAY FOR SDZ039-040.
BLIZZARD WARNING FROM 4 AM TO 7 PM CDT MONDAY FOR SDZ039-040.
MN...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 PM CDT
MONDAY FOR MNZ089-090-097-098.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM CDT
MONDAY FOR MNZ071-072-080-081.
BLIZZARD WARNING FROM 4 AM TO 7 PM CDT MONDAY FOR MNZ071-072-080-
081.
IA...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 PM CDT
MONDAY FOR IAZ001>003-012>014-020>022-032.
WIND ADVISORY FROM 4 AM TO 7 PM CDT MONDAY FOR IAZ031.
NE...WIND ADVISORY FROM 4 AM TO 7 PM CDT MONDAY FOR NEZ013-014.
&&
$$
SHORT TERM...CHAPMAN
LONG TERM...JM
AVIATION...CHAPMAN
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
556 PM EDT SUN MAR 17 2013
.SYNOPSIS...
COLD AIR DAMMING IS IN CONTROL OF THE AREA WITH A STATIONARY
FRONT TO THE SOUTH...AND WILL REMAIN IN PLACE THROUGH MOST OF THE
DAY MONDAY...UNTIL A COLD FRONT APPROACHES FROM THE WEST LATE IN
THE DAY. THE FRONT WILL TRY TO PUSH BACK NORTH AS A WARM FRONT
LATE IN THE DAY BUT THE WARM AIR WILL LIKELY ONLY WORK ITS WAY
BACK INTO FAR SOUTHWEST VIRGINIA AND PARTS OF THE PIEDMONT BY LATE
MONDAY. WIDESPREAD BUT GENERALLY LIGHT PRECIPITATION... SOME IN
THE FORM OF WINTRY WEATHER ACROSS THE NORTH...WILL OVERSPREAD THE
AREA TONIGHT. THEN WINDY CONDITIONS SPREAD INTO THE REGION BEHIND
THE COLD FRONT BY TUESDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 555 PM EDT SUNDAY...
HAVE ADDED AREAS OF FOG IN THE COLD AIR DAMMING REGION WHERE
VISIBILITIES IN SOME SPOTS WERE BELOW ONE MILE.
AS OF 410 PM EDT SUNDAY...
COLD WEDGE REMAINS IN PLACE ACROSS THE REGION...WITH PATCHES OF
DRIZZLE AND SOME MAINLY LIGHT FOG EXCEPT FOR RIDGES. TEMPERATURES
AND DEW PTS SO FAR REMAIN ABOVE FREEZING AT REPORTING STATIONS IN
THE AREA ALTHOUGH TEMPS HAVE REMAINED STEADY OR SLOWLY FALLING
THIS AFTERNOON WITH MUCH COLDER AIR NOT TOO FAR OFF TO THE NORTH.
MODELS STRUGGLING WITH QPF ALONG 850 FRONT TO OUR NORTHWEST AND
HAVE BEEN TRYING TO PUSH PRECIP IN ACROSS SE WV MOST OF THE DAY.
APPEARS LOOKING AT RADAR AND SOME HELP FROM HRRR THAT THOSE AREAS
WILL HAVE TO WAIT UNTIL AFTER 00Z BEFORE IT BEGINS TO SNEAK INTO
WRN GREENBRIER AGAIN. ALSO MODELS LIKELY OVERDOING SOME UPSLOPE
PRECIP ALONG BLUE RIDGE THIS EVENING...WHICH WILL BE MORE IN THE
FORM OF DRIZZLE...BUT COULD AMOUNT TO A FEW HUNDREDTHS SO WENT
AHEAD AND INCLUDED HIGH CHC TO LIKELY...INCREASING AS THE EVENING
PROGRESSES.
MAIN QSTN OVERNIGHT IS WHICH LOCATIONS WILL SEE FROZEN
PRECIP...AND WITH BIG DIFFERENCES IN TEMP PROFILES ALOFT...THIS IS
TRICKY. NAM STILL HAS STRONG WARM NOSE AND WITH THE COLDEST SFC
TEMPS SUGGEST MANY LOCATIONS FROM NRV NORTHWARD WOULD SEE FREEZING
RAIN. GFS...RAP...AND MANY SREF MEMBERS HAVE WEAK TO NO WARM
NOSE...AND THIS IS THE IDEA WE ARE STILL LEANING WITH IN THE
FORECAST...WHICH WOULD SUGGEST SLEET OR SNOW...THE FARTHER NORTH
UP TOWARD NORTHERN BORDER WITH WFO STERLING...THE MORE SNOW.
PROBLEM IS THE QPF. MOST OF THIS COMES IN BEFORE 06Z...AND MANY
AREAS WOULD STILL BE SEEING RAIN...EXCEPT FOR HIGHEST ELEVATIONS.
ALSO THINK MODELS ARE A BIT OVERDONE ON QPF. WHAT DOES FALL AFTER
MIDNIGHT WOULD BE THE SLEET AND SNOW MIX...BUT PRECIP AMOUNTS WILL
BE FROM A TENTH TO A QUARTER OF AN INCH BY THEN.
BASED ON THIS...LEANED TOWARD LOWER SLEET/SNOW TOTALS THAN
PREVIOUS FORECAST...BUT THIS STILL GIVES 1 TO 3 INCHES ACROSS FAR
NORTH...MAINLY GREENBRIER TO BATH TO ROCKBRIDGE AND INTO HIGHER
ELEVATIONS ALONG BLUE RIDGE. AN INCH OR SO FROM CRAIG TO ROANOKE
TO AMHERST AND PARTS OF GREENBRIER. ONE THING TO CONSIDER IS THE
POSSIBILITY OF SHALLOW MOISTURE UPSLOPING ALONG BLUE
RIDGE...AND/OR THE WARM NOSE AS FCST BY THE NAM BEING A LITTLE
STRONGER...WHICH MIGHT RESULT IN SOME AREAS OF LIGHT FREEZING RAIN
OR FREEZING DRIZZLE. DID NOT INCLUDE THAT SPECIFICALLY IN
FCST... THIS POSSIBILITY IS ONE REASON WHY DECIDED TO LEAVE THE
ADVISORY GOING AS FAR SOUTH AS CRAIG AND BOTETOURT
COUNTIES...SINCE THE SNOW/SLEET ACCUMS WILL BE MINIMAL. ROADS MAY
NOT HAVE MANY PROBLEMS EITHER DUE TO RECENT WARM TEMPS...BUT
BRIDGES AND OVERPASSES...AS WELL AS SIDEWALKS MAY GET A LITTLE
SLICK WITH LIGHT SLEET/SNOW MIX.
WENT WITH COLDER GUIDANCE IN MET FOR LOWS TONIGHT...ACTUALLY 1-2
DEG COLDER IN UPSLOPE AREAS FROM EASTERLY FLOW...AND COLDER THAN
GUIDANCE FOR HIGHS ON MONDAY...WHICH WILL HAPPEN VERY LATE IN THE
DAY MOST PLACES. WITH WEDGE LIKELY ONLY BREAKING IN FAR SW AND
WESTERN RIDGES...AND POSSIBLE ALSO IN NC PIEDMONT AND PARTS OF
SOUTHSIDE VA...MANY LOCATIONS WILL SEE NEARLY STEADY TEMPS MONDAY.
SHOWERS WILL BE MOVING IN FROM THE WEST LATE IN THE DAY...WHICH
WILL PROVIDE MIXING TO HELP BREAK BREAK THE WEDGE...AND DECIDED
THAT TIMING OF ANY CONVECTIVE POTENTIAL LOOKS LATE ENOUGH TO NOT
MENTION UNTIL EVENING TIME FRAME. THE TRICKY PART OF MONDAY`S
FORECAST IS PERHAPS FASTER TIMING OF ARRIVAL OF SHOWERS IN THE
WEST...AND FASTER BREAKING WEDGE FOR PERHAPS MUCH WARMER
TEMPERATURES AROUND THE SOUTHERN PERIPHERY.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 400 PM EDT SUNDAY...
SURFACE FRONT PROGGED TO BE ON OUR DOORSTEP 8PM MONDAY. THIS FRONT
WILL SWEEP ACROSS THE AREA FROM WEST TO EAST DURING THE OVERNIGHT.
ANTICIPATING NEAR CATEGORICAL THREAT FOR RAIN JUST PRIOR TOO THE
FRONTAL PASSAGE WITH RAPID DECREASE IN PRECIP THREAT AFTER FROPA.
MODELS SUGGEST A QUARTER TO ABOUT A HALF INCH OF RAIN TO BE
ASSOCIATED WITH THE FRONTAL PASSAGE...TEMPERATURES WARM ENOUGH
THAT IT SHOULD BE ALL LIQUID...EXCEPT FOR SOME OF THE HIGHEST
ELEVATIONS WHERE PRECIP MAY CHANGE OVER TO BRIEF PERIOD OF SNOW B4
ENDING.
BY DAYBREAK TUESDAY...FRONT WILL BE EAST OF THE FORECAST AREA WITH
DOWNSLOPE WESTERLIES RESULTING IN CLEARING SKIES ALONG AND EAST OF
THE BLUE RIDGE. LINGERING LOW LEVEL MOISTURE IN THE MTNS MAY
RESULT IN A FLURRY OR TWO THERE.
THE UPPER AIR PATTERN DOES NOT CHANGE MUCH THROUGH MID WEEK WITH
RIDGE IN THE WESTERN CONUS AND TROF IN THE EAST. THIS SUPPORTS
COLDER THAN NORMAL TEMPERATURES ACROSS OUR AREA. NORTHWEST FLOW
TUESDAY WILL PERSIST RIGHT ON INTO WEDNESDAY WITH 85H TEMPS BLOW
FREEZING. FOR THE MOST PART...THE FLOW IS DRY. THERE IS AN UPPER
LEVEL DISTURBANCE WHICH IS PROGGED TO COME THROUGH DURING THE DAY
WEDNESDAY. THIS FEATURE MAY BRING SNOW SHOWERS AND FLURRIES...BUT
MORE IMPORTANTLY A REINFORCING SHOT OF COLD AIR THAT WILL SEND
TEMPERATURES WELL BELOW NORMAL WEDNESDAY NIGHT INTO THURSDAY AS
85H TEMPERATURES TEST M14 DEG C.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 400 PM EDT SUNDAY...
A BLOCKY HEMISPHERIC CIRCULATION IS ADVERTISED BY THE LONG RANGE
MODELS THROUGH NEXT WEEKEND...MARKED BY THREE STRONG POSITIVE HEIGHT
ANOMALIES. THE FIRST IS THROUGH THE BERING SEA WHILE THE SECOND AND
THIRD MERGE BETWEEN THE NORTH POLE AND THE DAVIS STRAIT.
TELECONNECTIONS FROM EACH AREA SUPPORT RIDGING JUST OFF THE WEST
COAST WITH BROAD TROUGHING FROM THE CENTRAL CONUS EASTWARD. THIS
VERY NEGATIVE AO PATTERN SUPPORTS BELOW NORMAL TEMPERATURES EAST OF
THE ROCKIES WITH THE POLAR FRONT ALONG THE GULF COAST.
WEATHER CHALLENGE DURING THIS TIME FRAME IS WHETHER ANY SORT OF
CYCLOGENESIS CAN TAKE PLACE ALONG THIS POLAR FRONT WHICH WILL BE
SITUATED SOUTH OF OUR FCST AREA...AND IF SO CAN ANY OF THIS ENERGY
GAIN ANY LATITUDE PER STRONG WESTERLIES WITHIN THE COLD TROUGH WHICH
WILL BE DIRECTLY OVERHEAD DURING THE PERIOD. FORECAST
SPREAD/UNCERTAINTY AND RUN-RUN CONTINUITY INCREASES SIGNIFICANTLY
HEADING INTO NEXT WEEKEND. RECENT ECMWF/ECMWF ENSEMBLES IN
PARTICULAR HAVE OFFERED MORE SUPPRESSED SOLUTIONS THAN RECENT
GFS/GEFS. THE GFS RUNS INSTEAD OFFER A DEEPER SERN US/MID-ATLC
COASTAL STORM. ENSEMBLES ARE MIXED/IN THE MIDDLE BUT OVERALL FAVOR
A SOLUTION WITH EMPHASIS OVER THE SRN/SERN US...THAT SOME SORT OF
SYSTEM WILL GET GENERATED. SINCE THERE IS NO SOLID CONSENSUS ON
HOW FAR NORTH THIS SYSTEM WILL TRACK...WILL ADVERTISE CHC POPS FOR
THE ENTIRE CWA...WITH FOCUS ON THE SUNDAY TIME FRAME...DAY 7. AS
LUCK WOULD HAVE IT...WINTER ISN`T OVER...SO PTYPE CHALLENGE WILL
ALSO COME INTO PLAY IF THE SYSTEM SPREADS ANY MOISTURE THIS FAR
NORTH.
&&
.AVIATION /22Z SUNDAY THROUGH FRIDAY/...
AS OF 115 AM EDT
SUNDAY...
VERY POOR AVIATION CONDITIONS ARE EXPECTED THIS AFTERNOON INTO
TOMORROW MORNING AS A FRONTAL BOUNDARY STALLS TO THE SOUTH OF THE
CWA AND COLD CANADIAN HIGH PRESSURE MOVES TOWARD THE NORTHERN MID-
ATLANTIC. MVFR TO IFR CIGS AND VSBYS WILL ONLY INTENSIFY AS RAIN
SERVES TO INTENSIFY THE WEDGE. AFT 06Z...THERE IS SOME CONCERN
FOR WINTER PCPN AT LWB/BCB/ROA...AND POSSIBLY LYH IN THE FORM OF
SN/PL. DO EXPECT ACCUMULATING SNOW AT LWB...BUT ANY WINTER PCPN
FOR ROA/BCB SHOULD BE CONFINED TO THE 08Z-14Z TIME FRAME AND ONLY
LIMITED ACCUMULATION EXPECTED BEFORE PCPN CHANGES BACK TO -RA.
EXTENDED AVIATION DISCUSSION...
SUNDAY THROUGH WEDNESDAY CAN BEST CHARACTERIZED AS UNSETTLED. THE
FRONTAL BOUNDARY WILL NOT COMPLETELY CLEAR THE AREA UNTIL TUESDAY
MORNING. UNTIL THEN PERIODS OF RAIN AND LOW CEILINGS WILL BRING
EXTENDED PERIODS OF MVFR/IFR CONDITIONS TO ALL TAF LOCATIONS.
CONDITIONS WILL IMPROVE DRAMATICALLY BY TUESDAY AFTERNOON AND LAST
THROUGH WEDNESDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR VAZ018>020-023-024-035.
NC...NONE.
WV...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR WVZ045.
&&
$$
SYNOPSIS...SK
NEAR TERM...AMS/SK
SHORT TERM...PM
LONG TERM...PM
AVIATION...JC/RAB
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
423 PM EDT SUN MAR 17 2013
.SYNOPSIS...
COLD AIR DAMMING IS IN CONTROL OF THE AREA WITH A STATIONARY
FRONT TO THE SOUTH...AND WILL REMAIN IN PLACE THROUGH MOST OF THE
DAY MONDAY...UNTIL A COLD FRONT APPROACHES FROM THE WEST LATE IN
THE DAY. THE FRONT WILL TRY TO PUSH BACK NORTH AS A WARM FRONT
LATE IN THE DAY BUT THE WARM AIR WILL LIKELY ONLY WORK ITS WAY
BACK INTO FAR SOUTHWEST VIRGINIA AND PARTS OF THE PIEDMONT BY LATE
MONDAY. WIDESPREAD BUT GENERALLY LIGHT PRECIPITATION... SOME IN
THE FORM OF WINTRY WEATHER ACROSS THE NORTH...WILL OVERSPREAD THE
AREA TONIGHT. THEN WINDY CONDITIONS SPREAD INTO THE REGION BEHIND
THE COLD FRONT BY TUESDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 410 PM EDT SUNDAY...
COLD WEDGE REMAINS IN PLACE ACROSS THE REGION...WITH PATCHES OF
DRIZZLE AND SOME MAINLY LIGHT FOG EXCAPT FOR RIDGES. TEMPERATURES
AND DEW PTS SO FAR REMAIN ABOVE FREEZING AT REPORTING STATIONS IN
THE AREA ALTHOUGH TEMPS HAVE REMAINED STEADY OR SLOWLY FALLING
THIS AFTERNOON WITH MUCH COLDER AIR NOT TOO FAR OFF TO THE NORTH.
MODELS STRUGGLING WITH QPF ALONG 850 FRONT TO OUR NORTHWEST AND
HAVE BEEN TRYING TO PUSH PRECIP IN ACROSS SE WV MOST OF THE DAY.
APPEARS LOOKING AT RADAR AND SOME HELP FROM HRRR THAT THOSE AREAS
WILL HAVE TO WAIT UNTIL AFTER 00Z BEFORE IT BEGINS TO SNEAK INTO
WRN GREENBRIER AGAIN. ALSO MODELS LIKELY OVERDOING SOME UPSLOPE
PRECIP ALONG BLUE RIDGE THIS EVENING...WHICH WILL BE MORE IN THE
FORM OF DRIZZLE...BUT COULD AMOUNT TO A FEW HUNDREDTHS SO WENT
AHEAD AND INCLUDED HIGH CHC TO LIKELY...INCREASING AS THE EVENING
PROGRESSES.
MAIN QSTN OVERNIGHT IS WHICH LOCATIONS WILL SEE FROZEN
PRECIP...AND WITH BIG DIFFERENCES IN TEMP PROFILES ALOFT...THIS IS
TRICKY. NAM STILL HAS STRONG WARM NOSE AND WITH THE COLDEST SFC
TEMPS SUGGEST MANY LOCATIONS FROM NRV NORTHWARD WOULD SEE FREEZING
RAIN. GFS...RAP...AND MANY SREF MEMBERS HAVE WEAK TO NO WARM
NOSE...AND THIS IS THE IDEA WE ARE STILL LEANING WITH IN THE
FORECAST...WHICH WOULD SUGGEST SLEET OR SNOW...THE FARTHER NORTH
UP TOWARD NORTHWERN BORDER WITH WFO STERLING...THE MORE SNOW.
PROBLEM IS THE QPF. MOST OF THIS COMES IN BEFORE 06Z...AND MANY
AREAS WOULD STILL BE SEEING RAIN...EXCEPT FOR HIGHEST ELEVATIONS.
ALSO THINK MODELS ARE A BIT OVERDONE ON QPF. WHAT DOES FALL AFTER
MIDNIGHT WOULD BE THE SLEET AND SNOW MIX...BUT PRECIP AMOUNTS
WILL BE FROM A TENTH TO A QUARTER OF AN INCH BY THEN.
BASED ON THIS...LEANED TOWARD LOWER SLEET/SNOW TOTALS THAN
PREVIOUS FORECAST...BUT THIS STILL GIVES 1 TO 3 INCHES ACROSS FAR
NORTH...MAINLY GREENBRIER TO BATH TO ROCKBRIDGE AND INTO HIGHER
ELEVATIONS ALONG BLUE RIDGE. AN INCH OR SO FROM CRAIG TO ROANOKE
TO AMHERST AND PARTS OF GREENBRIER. ONE THING TO CONSIDER IS THE
POSSIBILITY OF SHALLOW MOISTURE UPSLOPING ALONG BLUE
RIDGE...AND/OR THE WARM NOSE AS FCST BY THE NAM BEING A LITTLE
STRONGER...WHICH MIGHT RESULT IN SOME AREAS OF LIGHT FREEZING RAIN
OR FREEZING DRIZZLE. DID NOT INCLUDE THAT SPECIFICALLY IN
FCST... THIS POSSIBILITY IS ONE REASON WHY DECIDED TO LEAVE THE
ADVISORY GOING AS FAR SOUTH AS CRAIG AND BOTETOURT
COUNTIES...SINCE THE SNOW/SLEET ACCUMS WILL BE MINIMAL. ROADS MAY
NOT HAVE MANY PROBLEMS EITHER DUE TO RECENT WARM TEMPS...BUT
BRIDGES AND OVERPASSES...AS WELL AS SIDEWALKS MAY GET A LITTLE
SLICK WITH LIGHT SLEET/SNOW MIX.
WENT WITH COLDER GUIDANCE IN MET FOR LOWS TONIGHT...ACTUALLY 1-2
DEG COLDER IN UPSLOPE AREAS FROM EASTERLY FLOW...AND COLDER THAN
GUIDANCE FOR HIGHS ON MONDAY...WHICH WILL HAPPEN VERY LATE IN THE
DAY MOST PLACES. WITH WEDGE LIKELY ONLY BREAKING IN FAR SW AND
WESTERN RIDGES...AND POSSIBLE ALSO IN NC PIEDMONT AND PARTS OF
SOUTHSIDE VA...MANY LOCATIONS WILL SEE NEARLY STEADY TEMPS MONDAY.
SHOWERS WILL BE MOVING IN FROM THE WEST LATE IN THE DAY...WHICH
WILL PROVIDE MIXING TO HELP BREAK BREAK THE WEDGE...AND DECIDED
THAT TIMING OF ANY CONVECTIVE POTENTIAL LOOKS LATE ENOUGH TO NOT
MENTION UNTIL EVENING TIME FRAME. THE TRICKY PART OF MONDAYS
FORECAST IS PERHAPS FASTER TIMING OF ARRIVAL OF SHOWERS IN THE
WEST...AND FASTER BREAKING WEDGE FOR PERHAPS MUCH WARMER
TEMPERATURES AROUND THE SOUTHERN PERIPHERY.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 400 PM EDT SUNDAY...
SURFACE FRONT PROGGED TO BE ON OUR DOORSTEP 8PM MONDAY. THIS FRONT
WILL SWEEP ACROSS THE AREA FROM WEST TO EAST DURING THE OVERNIGHT.
ANTICIPATING NEAR CATEGORICAL THREAT FOR RAIN JUST PRIOR TOO THE
FRONTAL PASSAGE WITH RAPID DECREASE IN PRECIP THREAT AFTER FROPA.
MODELS SUGGEST A QUARTER TO ABOUT A HALF INCH OF RAIN TO BE
ASSICIATED WITH THE FRONTAL PASSAGE...TEMPERATURES WARM ENOUGH THAT
IT SHOULD BE ALL LIQUID...EXCEPT FOR SOME OF THE HIGHEST ELEVATIONS
WHERE PRECIP MAY CHANGE OVER TO BRIEF PERIOD OF SNOW B4 ENDING.
BY DAYBREAK TUESDAY...FRONT WILL BE EAST OF THE FORECAST AREA WITH
DOWNSLOPE WESTERLIES RESULTING IN CLEARING SKIES ALONG AND EAST OF
THE BLUE RIDGE. LINGING LOW LEVEL MOISTURE IN THE MTNS MAY RESULT
IN A FLURRY OR TWO THERE.
THE UPPER AIR PATTERN DOES NOT CHANGE MUCH THROUGH MID WEEK WITH
RIDGE IN THE WESTERN CONUS AND TROF IN THE EAST. THIS SUPPORTS
COLDER THAN NORMAL TEMPERATURES ACROSS OUR AREA. NORTHWEST FLOW
TUESDAY WILL PERSIST RIGHT ON INTO WEDNESDAY WITH 85H TEMPS BLOW
FREEZING. FOR THE MOST PART...THE FLOW IS DRY. THERE IS AN UPPER
LEVEL DISTURBANCE WHICH IS PROGGED TO COME THROUGH DURRING THE DAY
WEDNESDAY. THIS FEATURE MAY BRING SNOW SHOWERS AND FLURRIES...BUT
MORE IMPORTANTLY A REINFORCING SHOT OF COLD AIR THAT WILL SEND
TEMPERATURES WELL BELOW NORMAL WEDNESDAY NIGHT INTO THURSDAY AS 85H
TEMPERATURES TEST M14 DEG C.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 400 PM EDT SUNDAY...
A BLOCKY HEMISPHERIC CIRCULATION IS ADVERTISED BY THE LONG RANGE
MODELS THROUGH NEXT WEEKEND...MARKED BY THREE STRONG POSITIVE HEIGHT
ANOMALIES. THE FIRST IS THROUGH THE BERING SEA WHILE THE SECOND AND
THIRD MERGE BETWEEN THE NORTH POLE AND THE DAVIS STRAIT.
TELECONNECTIONS FROM EACH AREA SUPPORT RIDGING JUST OFF THE WEST
COAST WITH BROAD TROUGHING FROM THE CENTRAL CONUS EASTWARD. THIS
VERY NEGATIVE AO PATTERN SUPPORTS BELOW NORMAL TEMPERATURES EAST OF
THE ROCKIES WITH THE POLAR FRONT ALONG THE GULF COAST.
WEATHER CHALLENGE DURING THIS TIME FRAME IS WHETHER ANY SORT OF
CYCLOGENESIS CAN TAKE PLACE ALONG THIS POLAR FRONT WHICH WILL BE
SITUATED SOUTH OF OUR FCST AREA...AND IF SO CAN ANY OF THIS ENERGY
GAIN ANY LATITUDE PER STRONG WESTERLIES WITHIN THE COLD TROUGH WHICH
WILL BE DIRECTLY OVERHEAD DURING THE PERIOD. FORECAST
SPREAD/UNCERTAINTY AND RUN-RUN CONTINUITY INCREASES SIGNIFICANTLY
HEADING INTO NEXT WEEKEND. RECENT ECMWF/ECMWF ENSEMBLES IN
PARTICULAR HAVE OFFERED MORE SUPPRESSED SOLUTIONS THAN RECENT
GFS/GEFS. THE GFS RUNS INSTEAD OFFER A DEEPER SERN US/MID-ATLC
COASTAL STORM. ENSEMBLES ARE MIXED/IN THE MIDDLE BUT OVERALL FAVOR
A SOLUTION WITH EMPHASIS OVER THE SRN/SERN US...THAT SOME SORT OF
SYSTEM WILL GET GENERATED. SINCE THERE IS NO SOLID CONCENSUS ON HOW
FAR NORTH THIS SYSTEM WILL TRACK...WILL ADVERTISE CHC POPS FOR THE
ENTIRE CWA...WITH FOCUS ON THE SUNDAY TIME FRAME...DAY 7. AS LUCK
WOULD HAVE IT...WINTER AINT OVER...SO PTYPE CHALLENGE WILL ALSO COME
INTO PLAY IF THE SYSTEM SPREADS ANY MOISTURE THIS FAR NORTH.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
AS OF 115 AM EDT
SUNDAY...
VERY POOR AVIATION CONDITIONS ARE EXPECTED THIS AFTERNOON INTO
TOMORROW MORNING AS A FRONTAL BOUNDARY STALLS TO THE SOUTH OF THE
CWA AND COLD CANADIAN HIGH PRESSURE MOVES TOWARD THE NORTHERN MID-
ATLANTIC. MVFR TO IFR CIGS AND VSBYS WILL ONLY INTENSIFY AS RAIN
SERVES TO INTENSIFY THE WEDGE. AFT 06Z...THERE IS SOME CONCERN
FOR WINTER PCPN AT LWB/BCB/ROA...AND POSSIBLY LYH IN THE FORM OF
SN/PL. DO EXPECT ACCUMULATING SNOW AT LWB...BUT ANY WINTER PCPN
FOR ROA/BCB SHOULD BE CONFINED TO THE 08Z-14Z TIME FRAME AND ONLY
LIMITED ACCUMULATION EXPECTED BEFORE PCPN CHANGES BACK TO -RA.
EXTENDED AVIATION DISCUSSION...
SUNDAY THROUGH WEDNESDAY CAN BEST CHARACTERIZED AS UNSETTLED. THE
FRONTAL BOUNDARY WILL NOT COMPLETELY CLEAR THE AREA UNTIL TUESDAY
MORNING. UNTIL THEN PERIODS OF RAIN AND LOW CEILINGS WILL BRING
EXTENDED PERIODS OF MVFR/IFR CONDITIONS TO ALL TAF LOCATIONS.
CONDITIONS WILL IMPROVE DRAMATICALLY BY TUESDAY AFTERNOON AND LAST
THROUGH WEDNESDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR VAZ018>020-023-024-035.
NC...NONE.
WV...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR WVZ045.
&&
$$
SYNOPSIS...SK
NEAR TERM...SK
SHORT TERM...PM
LONG TERM...PM
AVIATION...JC/RAB
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
243 PM CDT SUN MAR 17 2013
.SHORT TERM...SUNDAY NIGHT AND MONDAY
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
CENTERED ACROSS THE CENTRAL GREAT LAKES EARLY THIS AFTERNOON. LIGHT
EAST FLOW OFF LAKE MICHIGAN IS PUSHING CLOUDS AND FLURRIES INTO THE
SHORELINE AREAS...BUT TOO MUCH DRY AIR IN PLACE TO REACH THE FOX
VALLEY. THE NEXT STORM SYSTEM IS EMERGING INTO THE NORTHERN PLAINS
AND LOOKS FAIRLY IMPRESSIVE ON SATELLITE IMAGERY. AS THIS CYCLONE
MOVES ACROSS THE AREA TOMORROW...SNOW AMOUNTS AND HEADLINES ARE THE
MAIN FORECAST CONCERNS.
TONIGHT...HIGH PRESSURE WILL SLIDE TO NEW ENGLAND AS THE NEXT STORM
SYSTEM MOVES EAST ACROSS THE PLAINS. MID AND HIGH CLOUDS WILL BE ON
THE INCREASE THROUGH THE NIGHT...AS THE LOW LEVEL PRESSURE GRADIENT
TIGHTENS. AS A RESULT OF MORE CLOUDS AND WIND...TEMPS WILL BE
SIGNIFICANTLY WARMER THAN LAST NIGHT AND MAINLY IN THE TEENS. THE
12Z MODEL SUITE SHOWS A SIMILAR TIMING OF THE ARRIVAL OF THE PRECIP
COMPARED TO WHAT THE PREVIOUS SHIFT SHOWED IN THE FORECAST.
THEREFORE...WILL ONLY SHOW SMALL CHANCES SNEAKING INTO CENTRAL
WISCONSIN BETWEEN 09-12Z.
MONDAY...THE STRONG SHORTWAVE WILL SWING AROUND THE NORTHERN
MISSISSIPPI VALLEY AND BECOME NEGATIVELY TILTED AS IT REACHES
CENTRAL WISCONSIN BY 00Z TUESDAY. SURFACE LOW PRESSURE WILL SHIFT
EAST FROM NORTHERN MINNESOTA TO NORTHERN WISCONSIN DURING THIS SAME
TIME. AS THE PREVIOUS SHIFT MENTIONED...THE SHORTWAVE WILL BRING
STRONG DYNAMICS AND MIXING RATIOS OF ABOUT 3 G/KG...WHICH WILL BE
SUFFICIENT TO PRODUCE SNOWFALL RATES OF AROUND A HALF INCH TO UP TO
ONE INCH PER HOUR (FOR BRIEF PERIODS OF TIME). THE BAND OF SNOW
SHOULD BE PROGRESSIVE...HOWEVER...AND LAST FOR AROUND 6 HOURS OR
SO. IN ADDITION...THE DENDRITIC GROWTH ZONE IS PRETTY HIGH AND NOT
THAT THICK....AND SURFACE TEMPS WILL BE APPROACHING 32 DEGREES OVER
NE WISCONSIN. THEREFORE...EXPECT LOWER SNOWFALL RATIOS THAT WHAT
THE MODELS INDICATE (13-15 TO 1) AND MORE LIKE 10-13:1. WITH
WIDESPREAD QPF AROUND 0.25-0.35...THIS WOULD PUT SNOWFALL AMOUNTS
AROUND 2-4 INCHES FOR MOST LOCATIONS (HIGHER OVER CENTRAL
WISCONSIN). BECAUSE OF FAIRLY BEEFY SNOWFALL RATES DESPITE SOME
AREAS BEING MARGINAL FOR ADVISORY CRITERIA SNOW...WILL ISSUE A
WINTER WEATHER ADVISORY FOR AREAS EXCEPT THE SOUTHERN FOX VALLEY AND
CENTRAL LAKE MICHIGAN SHORELINE. WEST WINDS KICK UP LATE MONDAY
AFTERNOON AND INTO MONDAY EVENING...SO WILL EXTEND THE ADVISORY
THROUGH MID EVENING OR SO TO COVER BLOWING AND DRIFTING CONCERNS.
.LONG TERM...MONDAY NIGHT THROUGH NEXT SUNDAY
PERIOD WILL BE DOMINATED BY BROAD TROF OVER THE CENTRAL US...WITH
WESTERLIES LYING OVER SOUTHERN HALF OF THE U.S. LOOK FOR PROGRESSIVE
PACIFIC SYSTEMS DIVING THRU THE PLAINS INTO SOUTHEAST U.S...LEAVING
NE WI DRY FOR THE MOST PART...WITH TEMPERATURES RUNNING WELL BELOW
NORMAL.
INITIALLY...UPPER LOW TO MOVE ACROSS THE NORTHERN GREAT LAKES MON
NIGHT. WRAP-AROUND MOISTURE AND CYCLONIC FLOW EXPECTED TO BRING
LIGHT SNOW ACROSS NE WI THRU AT LEAST THE FIRST HALF OF MONDAY NIGHT.
STRONG CAA AND GUSTY WEST WINDS EXPECTED MON NIGHT INTO TUE.
THOUGH WITH CLOUDS AND WINDS...BUMPED MIN TEMPS UP SLIGHTLY FROM
EARLIER SHIFT.
QUESTION THROUGH THE TUE THROUGH WED PERIOD...IS WAVES ROTATING
AROUND THE UPPER LOW AND CHANCE FOR LIGHT PCPN WITH EACH SYSTEM.
DID NOT MAKE CHANGE TO TUE FLURRY FORECAST...THOUGH POTENTIAL
EXIST FOR LIGHT SNOW ON WED...WITH TROF DROPPING SOUTH THROUGH
STATE.
LAKE EFFECT POSSIBLE TUE INTO THU WITH INCOMING COLD AIR MASS AND
MOISTURE CIRCULATING AROUND LOW...THOUGH WITH A W-NW WIND...THE
BETTER ACCUMULATION VALUES ARE EXPECTED TO STAY NORTH OF THE MI/WI
BORDER WITH A TENTH OR TWO OVER NW VILAS COUNTY POSSIBLE.
SOME WEAKENING OF THE BLOCKY PATTERN AT END OF MODEL RUN...THOUGH
NO GREAT WARM-UP IN SIGHT. SPRING POSTPONED FOR AT LEAST ANOTHER
WEEK. DROPPED MAX/MINS TO BELOW GUIDANCE VALUES AS CLIMO EXERTING
TOO MUCH INFLUENCE.
&&
.AVIATION...
A FEW MVFR CIGS WL LINGER ACRS THE N EARLY THIS MORNING. SOME MVFR
CIGS COULD DEVELOP OVER E-C WI LATER THIS MORNING AS WINDS SHIFT
E. OTHERWISE...VFR CONDITIONS EXPECTED. MUCH POORER FLIGHT
CONDITIONS ARE EXPECTED MON AS SNOW BAND MOVES ACRS THE AREA.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 7 AM TO 10 PM CDT MONDAY FOR WIZ005-
010-018-019-030-031-035>037-045.
WINTER WEATHER ADVISORY FROM 10 AM TO 10 PM CDT MONDAY FOR
WIZ011>013-020>022-038-039-073-074.
&&
$$
MPC/TE