Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/15/13
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1002 PM CDT THU MAR 14 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 03Z...
* POTENTIAL FOR FOG WITH MVFR VISIBILITY TO DEVELOP OVERNIGHT.
* LIGHT SOUTH TO SOUTHWEST WINDS.
PAW
//DISCUSSION...UPDATED 00Z...
AN UPPER LEVEL WAVE MOVED ACROSS NORTHERN IL THIS AFTERNOON WITH
AN AREA OF LIGHT SNOW AND FLURRIES. THE AREA OF SNOW HAS PUSHED
TO THE SOUTH OF THE TERMINALS BUT LEFT SCATTERED TO BROKEN CLOUDS
BASED AT 800 TO 1500 FEET IN ITS WAKE. THESE CLOUDS WILL CLEAR FROM
THE NORTHWEST OVERNIGHT. THE CLEARING WILL BE SHORT LIVED AS THE
NEXT SYSTEM MOVES INTO THE AREA FROM THE WEST ON FRIDAY WITH VFR-
LEVEL CEILINGS AND RA/SHRA.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* LOW CONFIDENCE IN FOG DEVELOPING.
* HIGH CONFIDENCE IN WIND TREND.
PAW
//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 CHICAGO/ROMEOVILLE IL
823 PM CDT THU MAR 14 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 00Z...
* MVFR AND IFR CEILINGS NOT FAR TO THE SOUTHWEST OF ORD AND MDW
COULD SPREAD INTO EITHER AIRPORT THIS EVENING.
* LIGHT SOUTH TO SOUTHWEST WINDS.
PAW
//DISCUSSION...UPDATED 00Z...
AN UPPER LEVEL WAVE MOVED ACROSS NORTHERN IL THIS AFTERNOON WITH
AN AREA OF LIGHT SNOW AND FLURRIES. THE AREA OF SNOW HAS PUSHED
TO THE SOUTH OF THE TERMINALS BUT LEFT SCATTERED TO BROKEN CLOUDS
BASED AT 800 TO 1500 FEET IN ITS WAKE. THESE CLOUDS WILL CLEAR FROM
THE NORTHWEST OVERNIGHT. THE CLEARING WILL BE SHORT LIVED AS THE
NEXT SYSTEM MOVES INTO THE AREA FROM THE WEST ON FRIDAY WITH VFR-
LEVEL CEILINGS AND RA/SHRA.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* LOW CONFIDENCE IN CEILING FORECAST THIS EVENING.
* HIGH CONFIDENCE IN WIND TREND.
PAW
//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 TOPEKA KS
555 PM CDT WED MAR 13 2013
.DISCUSSION...
SEE PREV DISCUSSION.
&&
.AVIATION...
MODELS SHOW LITTLE IN THE WAY OF FORCING OR DEEP MOISTURE. THEREFORE
A VFR FORECAST IS EXPECTED TO PERSISTS WITH A WEAK SFC TROUGH MOVING
ACROSS THE AREA THROUGH THE DAY THURSDAY. THE RAP AND NAM SHOW THE
LOW LEVEL JET INCREASING TO AROUND 40KTS OVERNIGHT SO CONTINUED WITH
LLWS.
WOLTERS
&&
.PREV DISCUSSION... /314 PM CDT WED MAR 13 2013/
TONIGHT THROUGH TOMORROW...VERY LITTLE SENSIBLE WEATHER ON TAP FOR
THE SHORT TERM PORTION OF THE FORECAST. ONCE BAND OF MID CLOUDS MOVE
SOUTHEAST EXPECT MOSTLY CLEAR SKIES OVERNIGHT. HIGH PRESSURE CENTER
WILL MOVE EAST AND WINDS WILL STRENGTHEN FROM THE SOUTH ...USHERING
IN WARMER TEMPERATURES. WEAK BOUNDARY DOES MOVE THROUGH TOMORROW BY
MIDDAY...WHICH ONLY SERVES TO SWITCH WINDS TO THE WEST AND CONTINUE
WARMING TREND.
HARDING
THURSDAY NIGHT THROUGH WEDNESDAY...A NORTHWESTERLY ZONAL FLOW WILL
BE IN PLACE ACROSS THE CONUS BY THE END OF THE WORK WEEK WITH A
SOUTHWESTERLY SURFACE FLOW AS AN AREA OF LOW PRESSURE OVER THE
NORTHERN PLAINS SINKS SOUTHWARD INTO THE CENTRAL PLAINS. WITH A MILD
DAY EXPECTED ON THURSDAY...LOWS THURSDAY NIGHT WILL ONLY DROP INTO
THE UPPER 30S/LOWER 40S DESPITE MOSTLY CLEAR SKIES. AS A
RESULT...CAN EXPECT A MILD START TO THE DAY ON FRIDAY...WITH MODELS
SHOWING 850MB TEMPERATURES SOARING UPWARDS OF 14C-16C DEGREES BY THE
AFTERNOON HOURS. WITH THE SOUTHWESTERLY SURFACE FLOW INCREASING
THROUGH THE DAY...COULD SEE AFTERNOON HIGHS TOPPING OUT IN THE
LOW/MID 70S ACROSS FAR NORTHERN AND NORTHEAST KANSAS AND INTO THE
MID/UPPER 70S ACROSS CENTRAL AND EAST CENTRAL KANSAS. MODELS SHOW
THE SURFACE LOW TRACKING EASTWARD ACROSS THE FORECAST AREA BY FRIDAY
AFTERNOON...WITH A COLD FRONT MOVING THROUGH THE CWA FRIDAY NIGHT
AND IT LOOKS TO BE SOUTH OF THE AREA AFTER MIDNIGHT.
SATURDAY AND SUNDAY...SURFACE HIGH PRESSURE WILL SPREAD SOUTHWARD
ACROSS THE NORTHERN AND CENTRAL PLAINS BEHIND THE FRONT WITH
TEMPERATURES EXPECTED TO DROP BACK DOWN TO JUST BELOW THE SEASONAL
NORMALS AS SURFACE WINDS SHIFT TO THE NORTHEAST. MODELS CONTINUE TO
SHOW A FEW WEAK WAVES DEVELOPING WITHIN THE ZONAL FLOW DURING THE
SATURDAY TO SUNDAY TIMEFRAME. THERE IS STILL UNCERTAINTY
AMONGST THE MODELS REGARDING THE EXACT TRACKING OF THESE WAVES AND
THE BEST TIMING OF ANY LIGHT PRECIPITATION...BUT PRECIPITATION
CHANCES CURRENTLY LOOK TO INCREASE BY SATURDAY NIGHT AS A BIT MORE
MOISTURE MOVES INTO THE AREA. WITH TEMPERATURES DROPPING TO
AROUND THE FREEZING MARK EARLY SUNDAY MORNING OVER NORTHERN AND
NORTHEAST KANSAS...COULD SEE A BRIEF PERIOD OF A RAIN/SNOW MIX. HIGH
TEMPERATURES SATURDAY AND SUNDAY ARE EXPECTED TO BE IN THE UPPER 40S
TO LOWER 50S.
SUNDAY NIGHT THROUGH MONDAY...A MORE WELL-DEFINED SHORTWAVE TROUGH
WILL DEVELOP ACROSS THE NORTHERN PLAINS SUNDAY NIGHT AND PROGRESS
EASTWARD TOWARD THE GREAT LAKES REGION ON MONDAY. SURFACE LOW
PRESSURE ASSOCIATED WITH THIS WAVE WILL DRAG A COLD FRONT EASTWARD
THROUGH THE FORECAST AREA LATE SUNDAY NIGHT INTO MONDAY
MORNING...BRINGING A BETTER CHANCE FOR PRECIPITATION BEFORE EXITING
EAST OF THE AREA BY MONDAY AFTERNOON. ONCE AGAIN...LOW TEMPERATURES
EARLY MONDAY MORNING COULD BE NEAR THE FREEZING MARK ACROSS NORTHERN
AND NORTHEAST KANSAS SO THERE MAY BE A BIT OF A RAIN/SNOW MIX BEFORE
TRANSITIONING BACK OVER TO RAIN.
TUESDAY AND WEDNESDAY...ONCE THIS WAVE PASSES TO THE
EAST...NORTHWESTERLY ZONAL FLOW WILL RETURN TO THE CENTRAL CONUS
WITH DRY CONDITIONS EXPECTED AS SURFACE HIGH PRESSURE BUILDS INTO
THE NORTHERN AND CENTRAL PLAINS. TEMPERATURES LOOK TO BE BACK ON THE
RISE BY WEDNESDAY WITH A RETURN OF ABOVE-NORMAL TEMPERATURES.
ACH
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
755 PM EDT THU MAR 14 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 357 PM EDT THU MAR 14 2013
WATER VAPOR LOOP AND RUC ANALYSIS SHOWS A NW ALOFT OVER THE UPPER
GREAT LAKES BETWEEN THE WRN CONUS RDG AND TROF OVER THE EAST COAST.
ONE SHORTWAVE MOVING INTO NW ONTARIO WAS BRINGING AN INCREASE IN
CLOUD COVER THERE SOUTHWARD INTO THE ARROWHEAD OF MN AND NW WI. HIGH
PRESSURE OVER MUCH OF THE WRN GREAT LAKES HAS SUPPORTED MOSTLY SUNNY
SKIES INTO THE AFTERNOON HOURS ACROSS MUCH OF THE CWA. AS A RESULT
OF THE SUNNY SKIES...TEMPERATURES THUS FAR HAVE RISEN INTO THE MID
30S ACROSS MUCH OF THE INTERIOR WEST THIS AFTERNOON.
THE ONTARIO SHORTWAVE IS EXPECTED TO REMAIN WELL NORTH OF LAKE
SUPERIOR AS IT CONTINUES TO TRACK ESE ACROSS THE PROVINCE TONIGHT.
MUCH OF THE MOISTURE/FORCING AND THUS SNOW SHOULD STAY OVER THE
NORTHEAST HALF OF LAKE SUPERIOR...BUT THE ASSOCIATED SURFACE TROUGH
AND LOW LEVEL MOISTURE ON THE BACK SIDE SHOULD BE ENOUGH TO PRODUCE
A SOME SNOW SHOWERS ACROSS UPPER MICHIGAN TONIGHT. WILL CONTINUE
MENTION OF HIGHER CHC TO LIKELY POPS ACROSS THE NRN TIER WITH THE
PASSAGE OF THE FRONT. AS WINDS SHIFT TO THE WEST AND THEN
NORTHERLY...EXPECT A TRANSITION TO LAKE ENHANCED/LAKE EFFECT SNOW
AND WILL CONTINUE HIGHER POPS FOR NORTH FACING HIGHER TERRAIN WHERE
UPSLOPE WILL AID PRECIPITATION. SNOWFALL AMOUNTS WILL LIKELY BE
LIMITED AS TEMPS AT TOP OF MIXED LAYER (BTWN 900-875 MB) ONLY LOWER
TO ONLY AROUND -11C. OVER MOST OF THE NORTHERN AREAS...THE
PRECIPITATION WILL LIKELY BE SNOW. BUT FCST SNDGS SUGGEST DRYING
ALOFT BEHIND THE FRONT LATE TONIGHT...ESPECIALLY TOWARDS THE
IRONWOOD AREA...WHERE CLOUD LAYER IS IN THE MARGINAL AREA FOR ICE
CRYSTALS. WILL MENTION SLIGHT CHC FOR -FZDZ ALONG WITH SNOW LATE
TONIGHT. GIVEN MARGINALLY COLD TEMPS...EXPECT TOTAL SNOW
ACCUMULATION TO BE INCH OR LESS ACROSS THE NRN TIER COUNTIES.
MODELS CONTINUE TO TREND WEAKER AND FARTHER SOUTH WITH NEXT
SHORTWAVE MOVING IN OFF THE PAC NW FOR FRI AFTERNOON WITH MAJORITY
OF MODELS KEEPING RESULTING PCPN TO THE SOUTH...MAINLY OVER CENTRAL
AND SRN WI. DUE TO THESE TRENDS HAVE DECIDED TO CUT BACK POPS EVEN
MORE DRAMATICALLY OVER THE CWA ON FRIDAY. JUST HAVE SLIGHT CHC POPS
IN OVER THE NRN COUNTIES FOR LINGERING LIGHT LES...MAINLY IN THE
MORNING. HAVE TRIMMED BACK POPS FOR SYSTEM SNOW TO SLIGHT CHC ALONG
THE WI BDR FRIDAY MORNING...ONLY RAISING TO 30 PCT POPS IN THE
AFTERNOON AS SYSTEM SLIDES JUST TO THE SOUTH.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 357 PM EDT THU MAR 14 2013
FRI NGT...MODELS HAVE CONTINUED TREND TOWARD A FARTHER S TRACK FOR
CLIPPER LO THRU THE OH RIVER VALLEY...ALLOWING DRY AIR ASSOCIATED
WITH HI PRES OVER ONTARIO TO HAVE A MORE SGNFT INFLUENCE ON UPR MI
WX. ALTHOUGH SOME DPVA/H85-5 QVECTOR CNVGC ASSOCIATED WITH A
TRAILING SHRTWV IS FCST TO MOVE OVER UPR MI AND H85 TEMPS FCST AS LO
AS -18C WOULD BE SUFFICIENT FOR LES...THE ACYC NATURE OF THE FCST
H925-85 FLOW...INVRN BASE NOT FAR FM 3K FT AGL...AND H85 DEWPTS FCST
AS LO AS -20C TO -40C WL NEGATIVELY IMPACT THIS POTENTIAL. GIVEN
THESE NEGATIVES AND THE OVERALL TREND TOWARD A FARTHER S TRACK FOR
THE CLIPPER...CUT PREVIOUS FCST POPS A BIT...WITH THE SOMEWHAT HIER
CHC POPS ALONG THE WI BORDER CLOSER TO THE LO TRACK AND IN THE
UPSLOPE AREAS OF THE NCNTRL IN LLVL NNE FLOW.
SAT...ANY LINGERING PCPN FM FRI NGT SHOULD DIMINISH EARLY AS THE
LLVL FLOW SHIFTS TO THE WSW IN ADVANCE OF APRCHG COLD FNT ASSOCIATED
WITH NEXT ARCTIC BRANCH SHRTWV DIGGING SEWD THRU ONTARIO. THIS FNT
IS FCST TO PUSH THRU THE NW ZNS LATE IN THE DAY. SINCE THE MOST
IMPRESSIVE ASSOCIATED DPVA AND LARGER SCALE FORCING ARE FCST TO PASS
TO THE N ON THE CYC SIDE OF UPR JET AXIS ACRS LK SUP AND MSTR RETURN
AHEAD OF THE COLD FROPA WL BE QUITE LIMITED WITH FCST PWAT UNDER
0.20 INCH...SUSPECT ACCOMPANYING PCPN WL BE LIMITED TO THE W HALF
WITH ONLY LO CHC POPS APPROPRIATE. THE ONE EXCEPTION MIGHT BE THE
AREA FM ONTONAGON COUNTY THRU THE KEWEENAW...WHICH WL BE CLOSER TO
THE SHARPER DPVA...WHERE UPSLOPE W FLOW ACCOMPANYING THE FROPA MIGHT
RESULT IN SOME ENHANCEMENT...AND WHERE FCST SDNGS SHOW FAIRLY DEEP
UNSTABLE LYR AS WELL AS SOME SHARP UVV WITHIN A DGZ SEVERAL THOUSAND
FEET DEEP. AT LEAST A BRIEF PERIOD OF HEAVIER... MORE NMRS SHSN
APPEAR PSBL IN THIS AREA IN THE AFTN.
SAT NGT...AS COLD FNT SWINGS THRU THE UPR LKS IN THE EVNG...EXPECT
THE SAME ADVANTAGES THAT WOULD BRING HIER POPS TO THE KEWEENAW TO
CAUSE MORE NMRS SHSN OVER AREAS NEAR LK SUP E OF MQT. BUT QUICK
ARRIVAL OF LARGER SCALE SUBSIDENCE IN THE DNVA/CAD BEHIND THE
SHRTWV...FCST STEADY TRANSITION TO MORE ACYC FLOW...AND EXPECTED
DRYNESS OF INCOMING AIRMASS WL TEND TO LIMIT THE LES IN THE WAKE OF
THE FROPA DESPITE ARRIVAL OF H85 THERMAL TROF/TEMPS ARND -20C. BEST
CHC FOR MORE PERSISTENT SHSN WL BE IN THE NW WIND SN BELTS E OF
MQT...WHERE LONGER FETCH/MOISTENING ACRS THE LK IN LLVL NW FLOW WL
MITIGATE THE LARGER SCALE DRYING. THE FROPA SHOULD BE DRY OVER THE
SCENTRAL GIVEN TRACK OF DYNAMIC SUPPORT/LACK OF MOISTENING.
SUN...EXPECT SFC HI PRES TO BLD OVER THE CWA IN ADVANCE OF APRCHG H5
SHRTWV RDG AND UNDER CONFLUENT WNW FLOW ALF. LINGERING SHSN NEAR LK
SUP SHOULD END BY AFTN WITH A COMBINATION OF NEGATIVE DYNAMICS/
INCRSG ACYC FLOW/DRYING/DAYTIME HEATING WITH INCRSG MARCH INSOLATION
DISRUPTING THE LES PROCESS. IN FACT...THE DAY IS LIKELY TO TURN
MOSUNNY IN THE AFTN W-E WITH WSHFT TO THE S FOLLOWING PASSAGE OF HI
PRES RDG AXIS. DESPITE THE RETURN OF MORE SUNSHINE...THE DAY WL
FEATURE BLO NORMAL MAX TEMPS MAINLY IN THE 20S WITH H85 TEMPS
RECOVERING TO -12C TO -14C IN THE AFTN.
SUN NGT THRU TUE...ALTHOUGH THERE IS INCRSG CONSENSUS A SGNFT LO
PRES WL DVLP SOMEWHERE NEAR THE GRT LKS EARLY NEXT WEEK...THE EXACT
DETAILS ON TIMING AND LOCATION/IMPACT ON UPR MI WL DEPEND ON THE
PHASING OF SHRTWVS EMBEDDED IN THE ARCTIC AND POLAR BRANCHES. SOME
FCSTS SUCH AS THE 00Z CNDN MODEL SHOW THE SHRTWVS REMAINING OUT OF
PHASE FOR A LONGER TIME WITH SFC LO INTENSIFICATION TOO FAR TO THE E
TO HAVE A REAL BIG IMPACT ON UPR MI. THE 00Z ECWMF ON THE OTHER HAND
INDICATED A QUICKER PHASING WITH A DEEP SFC LO OVER LOWER MI MON NGT
HAVING A SGNFT IMPACT ON THE CWA. ALTHOUGH THE NUMERICAL MODELS
OFTEN HAVE A DIFFICULT TIME WITH THE DETAILS OF THESE
INTERACTIONS...THE 12Z RUNS HAVE TRENDED TOWARD THE FASTER PHASING/
DEEPER LO CLOSER TO UPR MI. SO BUMPED POPS UP A BIT TO LIKELY OVER
THE CONSENSUS CHC POPS FCST.
EXTENDED...AS HAS BEEN COMMON RECENTLY...THE UPR FLOW DURING THE
EXTENDED WL FEATURE A BLOCKING PATTERN WITH AN UPR RDG OVER NE
CANADA HOLDING IN PLACE A CUTOFF LO OVER THE NE CONUS/FAR SE CANADA.
THIS NEGATIVE NAO PATTERN COMMONLY RESULTS IN BLO NORMAL TEMPS OVER
THE GREAT LKS AS COLD AIR IS LOCKED IN PLACE WITH N-NE FLOW BTWN
HUDSON BAY HI PRES AND THE CLOSED LO TO THE E. COMBINATION OF TREND
TOWARD DRIER...MORE ACYC FLOW WITH HUDSON BAY HI PRES RDG
DOMINATING/SUBSIDENCE WARMING OF H85 TEMPS/STRENGTHENING MAR SUN WL
TEND TO DISSIPATE LES THAT WL STILL BE ONGOING ON TUE NGT INTO WED
IN LLVL CYC NW FLOW LEFT IN THE WAKE OF SLOWLY DEPARTING SFC LO PRES
TOWARD THE CNDN MARITIMES/CUTOFF LO IN PLACE THERE. CONSIDERING THE
STRENGTH OF THE HUDSON BAY HI PRES/NEGATIVE NAO...THE 12Z GFS SEEMS
TOO AGGRESSIVE AT LIFTING A LO PRES NE TOWARD THE UPR LKS NEXT
WED/THU. EXCEPT FOR LINGERING LES ON WED...WENT DRY FOR THESE DAYS.
&&
.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 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 357 PM EDT THU MAR 14 2013
HIGH PRESSURE CURRENTLY OVER THE UPPER GREAT LAKES REGION WILL SLIDE
EAST TODAY AND LEAD TO INCREASING SOUTHERLY FLOW AHEAD OF AN
APPROACHING COLD FRONT. THIS FRONT WILL MOVE ACROSS LAKE SUPERIOR
TONIGHT AND SHIFT WINDS TO THE NORTH AT 20-30KTS. A HIGH PRESSURE
RIDGE WILL THEN NOSE OVER LAKE SUPERIOR ON FRIDAY FROM A PARENT HIGH
OVER NORTHERN ALBERTA AS NORTH WINDS GRADUALLY DIMINISH TO 15-25
KTS.
STEADY NE WINDS UP TO 25 KTS WILL DIMINISH FRI NIGHT AS HI PRES
RIDGE AXIS BUILDS OVER THE UPPER GREAT LAKES. A SHARP COLD FRONT
WILL SWING ACROSS THE AREA LATE SAT...WITH NW WINDS IN ITS WAKE
CLIMBING UP TO 30 KTS AND FREEZING SPRAY DEVELOPING. EXPECT THESE
WINDS TO DIMINISH QUICKLY SUN AS ANOTHER AREA OF HI PRES BUILDS INTO
THE UPPER LAKES. ANOTHER PERIOD OF STRONG N-NW WINDS ARE LIKELY ON
MON INTO TUE AS A LO PRES DEEPENS NEAR LOWER MI AND SHIFTS SLOWLY
INTO SE ONTARIO. DEPENDING ON HOW QUICKLY THIS LO DEVELOPS...NW
GALES/HEAVY FREEZING SPRAY WILL BE POSSIBLE...ESPECIALLY MON NIGHT
AND TUE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...KC
AVIATION...JLB
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
423 PM EDT WED MAR 13 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 421 PM EDT WED MAR 13 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF/
CLOSED UPR LO CENTERED JUST S OF JAMES BAY MOVING STEADILY TO THE
E...ALLOWING A RDG OVER THE ROCKIES TO EXPAND TO THE E...WITH
00Z-12Z H3 HGT RISES UP TO 150M EVIDENT OVER THE NRN PLAINS/UPR MS
RIVER VALLEY. ALTHOUGH A STEADY NNW FLOW BTWN ASSOCIATED SFC LO OVER
SE CANADA AND HI PRES RDG AXIS STRETCHING FM NW ONTARIO INTO THE
CENTRAL PLAINS IS PUSHING H85 TEMPS AS LO AS -13C TO -15C INTO THE
UPR LKS...THE AIRMASS IMMEDIATELY UPSTREAM IS SO DRY PER 12Z INL
RAOB THAT THERE ARE NO -SHSN OR EVEN MUCH IN THE WAY OF LK CLDS OVER
UPR MI ATTM. LOOKING A BIT FARTHER TO THE NW...THERE WAS SOME SC
NOTED EARLIER OVER PORTIONS OF NW ONTARIO ASSOCIATED WITH A BIT MORE
MSTR SHOWN ON THE 12Z YPL RAOB...BUT SUBSIDENCE ASSOCIATED WITH THE
APRCHG H3 HGT RISES/SFC ACYC FLOW AS WELL AS SOME DAYTIME HEATING
HAS CAUSED THIS CLD TO DISSIPATE. FARTHER TO THE NW...A SHRTWV
MOVING THRU ALBERTA AND INTO SASKATCHEWAN IS ROUNDING THE UPR RDG
OVER THE ROCKIES. MID/HI CLDS AHEAD OF THIS DISTURBANCE AND
ASSOCIATED WARM FNT OVER THE HI PLAINS ARE PUSHING E THRU THE
DAKOTAS/SCENTRAL CANADA THIS AFTN.
MAIN FCST CONCERNS IN THE SHORT TERM ARE CLD TRENDS/IMPACT ON TEMPS.
TNGT...ALTHOUGH LK CLDS HAVE DISSIPATED WITH ARRIVAL OF DRIER AIR/
DAYTIME HEATING WITH HIER MARCH SUN ANGLE THAT TENDS TO CAUSE
SUBSIDENCE OVER LK SUP...CONCERNED SOME CLDS WL REFORM THIS EVNG
WITH LOSS OF HEATING/ARRIVAL OF MSTR NOTED IN NW ONTARIO IN THE
PRESENCE OF H85 TEMPS NEAR -12C AND THEN SPREAD INLAND INTO MAINLY
THE NCENTRL AND ERN CWA IN NW FLOW AHEAD OF APRCHG HI PRES RDG AXIS.
BUT AS THE HI PRES RDG AXIS APRCHS FM THE W...INCRSG SUBSIDENCE/MORE
ACYC LLVL FLOW IS FCST TO SINK THE SUBSIDENCE INVRN LO ENUF ANY LO
CLD SHOULD DSPT W-E. ALTHOUGH FCST H85 TEMPS ARE MARGINAL FOR LES...
LO INVRN BASE 2-3K FT AGL WL LIMIT LES TO PERHAPS SOME FLURRIES OVER
THE ERN ZNS DOWNWIND OF THE LK IN LLVL NW FLOW. PREVIOUS FCST HAD A
REASONABLE HANDLE ON THESE EXPECTATIONS...SO MADE FEW CHANGES TO
THESE GRIDS. SOME MID/HI CLDS WELL IN ADVANCE OF APRCHG SHRTWV/WARM
FNT TO THE W ARE FCST TO MOVE INTO THE WRN ZNS LATE TNGT. BUT WITH A
PERIOD OF MAINLY CLR SKIES/LGT WINDS...WL MAINTAIN MIN TEMPS FCST
NEAR LO END OF GUIDANCE OVER MUCH OF THE INTERIOR W HALF.
THU...SHRTWV NOW MOVING THRU SCENTRAL CANADA OVER TOP OF ROCKIES RDG
IS FCST TO MOVE THRU NW ONTARIO. ALTHOUGH CLD WL OVERSPREAD UPR MI
W-E AHEAD OF THE WARM FNT...PASSAGE OF SHARPER DPVA/DEEP LYR QVECTOR
CNVGC TO THE N CLOSER TO TRACK OF DISTURBANCE AS WELL AS LIMITED
DEPTH OF ABSOLUTE MSTR RETURN SHOULD RESULT IN A DRY DAY. H85 TEMPS
ARE FCST TO RISE TO BTWN ABOUT -2C OVER THE W AND -8C OVER THE E BY
00Z FRI AS A SW FLOW DVLPS ON THE WRN FLANK OF RETREATING HI PRES...
SO EXPECT A WARMER DAY ESPECIALLY OVER THE W HALF.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 421 PM EDT WED MAR 13 2013
UPPER LEVEL PATTERN STARTS OFF LONG TERM WITH ELONGATED TROUGH OVER
MOST OF NORTHERN AND EASTERN CANADA AND RIDGING OVER WESTERN CANADA.
OVER TIME RIDGE IS FLATTENED AS TROUGHING OVR CANADA SETTLES INTO
NORTHERN TIER OF CONUS THROUGH THE UPCOMING WEEKEND. ZONAL WNW FLOW
RESULTS AND WILL BRING STRONGER SHORTWAVE ACROSS NORTHERN PLAINS AND
UPPER GREAT LAKES THURSDAY NIGHT AND FRIDAY. TRICKY SYSTEM WITH
REGARD TO NORTHERN EXTENT OF HEAVIER SNOW. AS ALLUDED TO YDY...WILL
GREATLY DEPEND ON HOW FAR SOUTH SFC-H85 BAROCLINIC ZONE ALLIGNS IN
WAKE OF NORTHERN STREAM SHORTWAVE MOVING THROUGH THURSDAY NIGHT. GFS
AND GEM-NH FARTHER SOUTH /12Z GFS TRENDED EVEN FARTHER SOUTH/ WHILE
NAM IS MUCH FARTHER NORTH. ECMWF/UKMET A COMPROMISE...BUT THE ECMWF
DID TREND FARTHER SOUTH COMPARED TO THE 12Z RUN FROM YDY/12 MARCH.
SEEMS LIKE THE NAM IS BECOMING MORE OF A NORTHERN OUTLIER...SO WILL
TEND TO TREND AWAY FROM THAT IDEA AND ANY MODELS THAT ARE
INITIALIZED OFF OF IT SUCH AS OUR LOCAL WRF. STILL THINK THAT THE
LOCATION OF TIGHTER LOW-LEVEL TEMPERATURE GRADIENT WILL BE
ULTIMATELY WHERE HEAVIEST QPF/SNOW SETS UP ON FRIDAY AS SHORTWAVE
AND SFC-H85 LOWS MOVE IN FROM NORTHERN PLAINS.
WHERE THE TIGHT THERMAL GRADIENT OCCURS THERE IS A POTENTIAL FOR A
NARROW STRIPE OF HEAVY SNOW DUE TO LOW-MID LEVEL FRONTOGENESIS AMD
DIVERGENCE ALOFT FROM RIGHT ENTRANCE REGION OF JET STREAK DROPPING
INTO GREAT LAKES FROM ONTARIO ALONG WITH DECENT MOISTURE ADVECTION
WITH H7 MIXING RATIOS 3-4G/KG. SFC-H85 LOWS/LOW-LEVEL FLOW IS
SHOWING A STRENGTHENING TREND OVERALL AS WELL. BASED ON MODEL
CONSENSUS...SEEMS LIKE BETTER CHANCE FOR ENHANCEMENT/HEAVIER SNOW TO
COME TOGETHER MAY END UP JUST TO OUR SOUTH. WILL KEEP POPS LIKELY
TOWARD THE WEST AND SOUTH...WHERE MODEL AGREEMENT IS HIGHER THAT
SNOW OCCURS. MAY NEED HEADLINES...LIKELY ADVISORIES...IN THESE AREAS
FRIDAY INTO FRIDAY EVENING. WWD DAY2 GRAPHICS INDICATE SWATH OF 2-4
INCHES OF SNOW FRIDAY ALONG WI BORDER...WITH JUST A COUPLE INCHES
OVER NORTHERN UPR MICHIGAN. BASED ON CROSS SECTIONS FROM GFS AND
JUST THE LOOK FROM QPF FIELDS...COULD BE A VERY SHARP CUTOFF TO SNOW
ON NORTH SIDE. AS AGEOSTROPIC CIRCULATION WITHIN H85-H7 FRONTOGENEIS
OCCURS THERE ARE INDICATIONS THAT SUBSIDENCE AREA OVER NORTHERN UPR
MICHIGAN WILL DRAW INCREASINGLY DRIER AIR IN FROM CANADA. GRADIENT
OF SNOW AMOUNTS MAY END UP SIMILAR TO SNOW EVENT FROM LATE MARCH OF
2011 THAT IMPACTED FAR SOUTH CENTRAL CWA WITH OVER A FOOT OF SNOW
WHILE NORTHERN CWA ONLY SAW FLURRIES. WE SHALL SEE. ONCE SNOW TAPERS
OFF...DESPITE SUFFICIENT COLD AIR IN LOW-LEVELS...UNSURE ON EXTENT
OF LK EFFECT GIVEN CONCERNS WITH THE DRY AIR.
FAIRLY QUIET LATER FRIDAY NIGHT INTO SATURDAY MORNING. MAY SEE SOME
SNOW SHOWERS FLARE UP SATURDAY AFTN INTO SATURDAY NIGHT WITH ARRIVAL
OF SHORTWAVE/COLD AIR ADVECTION DRIVING H85 TEMPS DOWN TO NEAR -20C.
MODELS HINT AT SHARPER LOW-LEVEL TROUGH MOVING THROUGH SATURDAY
EVENING WHICH MAY ALSO ENHANCE THE SNOW. INCREASED POPS A BIT INTO
SATURDAY NIGHT. GIVEN FAVORABLE LOCATION OF DGZ WITHIN MOIST LAYER
PRESENT WITH LAKE EQLS UP TO 10KFT...MAY SEE SEVERAL INCHES OF
FLUFFY SNOW ALONG LK SUPERIOR. INVERSION LOWERS BLO 5KFT THROUGH
DAY ON SUNDAY...BUT ENOUGH COLD AIR LINGERS FOR NW FLOW AREAS TO SEE
SCT LK EFFECT SNOW SHOWERS.
ATTN THEN TURNS TO SHORTWAVE TROUGHING DIGGING ACROSS ROCKIES BY
SUNDAY HELPING TO DEEPEN SFC LOW ON THE LEE SIDE OF THE ROCKIES.
UPPER TROUGH/SFC LOW IS FORECAST TO HEAD EAST AND DEEPEN AS
SHORTWAVE IN THE NORTHERN BRANCH ATTEMPTS TO PHASE WITH THE SOUTHERN
STREAM SYSTEM. SFC LOW DEEPENS FURTHER AND LIFTS ACROSS GREAT LAKES
WHICH MAY LEAD TO A SIGNIFICANT SNOW STORM OVER PORTIONS OF THE
UPPER GREAT LAKES. UP TO 12Z THERE WAS ACTUALLY GOOD AGREEMENT FROM
THE ECMWF AND GFS ON TRACK OF THE LOW. 12Z ECMWF JOGGED FARTHER WEST
THOUGH IT WOULD STILL BE MAINLY A SNOW EVENT. WAVES PRODUCING THIS
WEATHER SYSTEM ARE STILL WELL TO THE NORTH...UNDERSTATEMENT...OVER
THE NORTHWEST TERRITORIES OF CANADA...AND IN THE VCNTY OF THE NORTH
POLE. THERE IS A LOT OF INTERACTION THAT HAS TO OCCUR YET BTWN THESE
WAVES...AND LIKELY OTHERS AS WELL...BEFORE A FINAL SOLUTION IS
DETERMINED. CERTAINLY A SYSTEM TO WATCH THOUGH AS IT WILL HAVE GULF
MOISTURE TO WORK ON. CONVECTION TO THE SOUTH TOO SO THAT INTERACTION
WILL NEED TO BE ADDRESSED BY MODELS AS WELL. MID SHIFT PUT A MENTION
IN HWO...WHICH SEEMS LIKE GOOD CALL IN THIS SITUATION. STRONGER
SYSTEM DRAWS DOWN CONTINUAL COLD AIR ACROSS LK SUPERIOR THROUGH
MIDWEEK SO PUT CHANCE POPS IN OVER NORTHERN CWA. LAST PANELS OF GFS
AND ECMWF INDICATE SOME POTENTIAL FOR MODERATING TEMPS TOWARD LAST
WEEK OF MARCH AS MEAN TROUGH ATTEMPTS TO SHIFT INTO EASTERN CANADA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 126 PM EDT WED MAR 13 2013
EXPECT PREDOMINANT VFR CONDITIONS AND SLOWLY DIMINISHING WINDS THIS
AFTN AS HI PRES RDG AXIS/AREA OF DRIER LLVL AIR MOVES SLOWLY EWD AND
PRES GRADIENT WEAKENS. NEXT CONCERN IS IMPACT OF AREA OF LLVL MSTR
THAT IS PRESENT OVER NW ONTARIO. NUMERICAL GUIDANCE SHOWS THIS MOIST
AIR STREAMING SEWD ACRS LK SUP AND INTO MAINLY NCENTRAL AND ERN UPR
MI IN THE NW FLOW AHEAD OF THE ENCROACHING HI. CONCERNED THERE COULD
BE SOME LK CLDS THAT FORM WITHIN THE CHILLY AIRMASS AFTER SUNSET
ESPECIALLY AT CMX/SAW...SO RETAINED FCST OF HI END MVFR CIGS BTWN
00Z-06Z AT CMX/SAW. AS THE HI PRES RDG MOVES CLOSER...EXPECT
SUBSIDENCE INVRN TO LOWER ENUF LATE TNGT TO DISSIPATE ANY MVFR CLDS
THAT DO FORM. ALTHOUGH SOME MID/HI CLDS WL INVADE THE AREA ON THU...
PREVAILING DRY LLVL AIR WL RESULT IN VFR CONDITIONS.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 421 PM EDT WED MAR 13 2013
AS HI PRES RIDGE AXIS MOVES IN FROM THE W TONIGHT...THE PRES
GRADIENT WILL WEAKEN OVER LAKE SUP...CAUSING NNW WINDS UP TO 30 KTS
LATE THIS AFTERNOON OVER THE E HALF TO DIMINISH AND FREEZING SPRAY
TO END. WINDS WILL SHIFT TO THE SW ON THU AS THE RIDGE AXIS MOVES TO
THE E...BUT WINDS WILL BE UNDER 20 KTS UNTIL LATE IN THE DAY OVER
THE W AS ANOTHER TROF APPROACHES FROM THE NW AND SHARPENS THE PRES
GRADIENT.
DUE TO THAT TIGHTER PRESSURE GRADIENT...W WINDS TO 25 KTS INCREASE TO
30 KTS WHILE SHIFTING N-NW ON THU NIGHT. SLIGHT RISK THAT GALE GUSTS
COULD OCCUR RIGHT IN WAKE OF THE WIND SHIFT THURSDAY EVENING OVER
EASTERN LK SUPERIOR. EXPECT N-NE WINDS TO 25 KTS THROUGH FRI AS LOW
PRESSURE PASSES SOUTH OF THE REGION. AFTER LIGHTER WINDS INTO SAT
MORNING ANOTHER TROUGH WILL SHIFT WINDS TO NW TO 25 KTS SAT NIGHT.
WINDS DIMINISH ON SUN BUT INCREASE YET AGAIN LATE ON MON AS STRONG
LOW PRESSURE SYSTEM LIFTS ACROSS THE UPR LAKES REGION. &&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...JLA
AVIATION...KC
MARINE...KC/JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
127 PM EDT WED MAR 13 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 447 AM EDT WED MAR 13 2013
WV IMAGERY AND RUC ANALYSIS UPPER TROUGH IS STILL ROTATING OVER THE
GREAT LAKES REGION THIS MORNING. THE ABUNDANT MOISTURE WITH THIS
UPPER LOW AND 850MB TEMPERATURES AROUND -16C LED TO MODERATE TO
HEAVY LAKE EFFECT SNOW OFF LAKE SUPERIOR YESTERDAY INTO THE
OVERNIGHT HOURS. AS OF 2AM...THE SNOWFALL TOTAL AT OUR OFFICE HAD
REACHED 8.7 INCHES. BUT MID LEVEL DRYING...SEEN ON THE 00Z KINL AND
CWPL SOUNDINGS ALONG WITH IR SATELLITE OVER WESTERN LAKE
SUPERIOR...HAD BROUGHT A QUICK END TO THE SNOW OVER THE WESTERN CWA
SHORTLY AFTER MIDNIGHT AND RECENT RADAR TRENDS OVER THE CENTRAL AND
EAST SHOW SIMILAR QUICK DECREASE.
UPPER RIDGE AND SURFACE HIGH PRESSURE WILL BE BUILDING IN TODAY AND
REMAINING INTO TONIGHT. THIS WILL CONTINUE TO PULL THE DRY AIR OVER
THE AREA AND SHOULD BRING AN END TO THE LINGERING SNOW SHOWERS OVER
THE EAST DURING THE MORNING HOURS. WITH THE QUICK DECREASE TO THE
SNOW...DECIDED TO DROP THE REMAINING WINTER WX ADVISORIES OVER THE
EAST. THE GUSTY WINDS TODAY WILL KEEP SOME BLOWING SNOW IN THE
FORECAST...WITH THE BEST CHANCES NEAR LAKE SUPERIOR EAST OF
MARQUETTE.
BASED ON LATEST TRENDS...HAVE OPTED TO GO MORE A LITTLE MORE
OPTIMISTIC ON THE CLOUD COVER FOR TODAY. THE QUICK TRANSITION TO
VFR AND MID CLOUDS OVER THE WEST SHOWS A LACK OF LOW LEVEL MOISTURE
EVENTHOUGH 850MB TEMPS ARE STILL AROUND -14C. THERE IS JUST ENOUGH
TERRAIN ENHANCEMENT TO AID CLOUD COVER OVER THE WEST AND THAT COULD
BE THE CASE TODAY...ESPECIALLY WITH SOME DIURNAL HEATING HELP.
THUS...AFTER THE DEEPER MOISTURE DEPARTS THIS
MORNING...TRANSITIONED TO A PARTLY CLOUDY SKY WITH THE GREATEST
CLEARING NEAR THE WISCONSIN BORDER. HIGHS TODAY WILL REMAIN BELOW
NORMAL WITH MOST LOCATIONS IN THE MID-UPPER 20S.
FOR TONIGHT...MODELS STILL HINTING AT A INCREASE IN THE MOISTURE IN
THE 925-875MB RANGE LATE THIS AFTERNOON INTO THIS EVENING FROM THE
KEWEENAW SOUTHEAST THROUGH MARQUETTE/ALGER COUNTIES. 875MB TEMPS
AROUND -12.5C WOULD SUPPORT ENOUGH INSTABILITY FOR SOME SNOW
SHOWERS...BUT CONCERN IS THE DEPTH OF THE CLOUD LAYER WHICH WILL
LIKELY ONLY BE 2-3KFT. THERE WAS A THIN AREA OF CLOUDS THIS PAST
EVENING WHERE THE MODELS ARE SHOWING THE LOW MOISTURE...BUT IT HAS
SINCE DISSIPATED. THAT MOISTURE MAY STILL BE PRESENT AND WITH THE
INFLUENCE OF LAKE SUPERIOR...PUT IN A MENTION OF ISOLATED
FLURRIES FOR ALGER/LUCE/SCHOOLCRAFT COUNTIES.
OTHERWISE...HIGH PRESSURE SHOULD BE IN PLACE OVER THE AREA AND LEAD
TO A QUIET NIGHT. THE WESTERN CWA WILL LIKELY BE MOSTLY CLEAR
DURING THE EVENING HOURS BEFORE MID/HIGH CLOUDS START STREAMING IN
AHEAD OF THE NEXT SHORTWAVE DROPPING THROUGH THE NORTHWEST FLOW
ALOFT. THINKING THE HIGH CLOUDS WILL BE IN BY MIDNIGHT AND THEN
THEY WILL THICKEN/LOWER THROUGH THE NIGHT AND COVER ALL OF THE
WESTERN CWA BY MORNING. THIS GIVES CONCERN TO LOWS FOR TONIGHT...AS
THE CLOUD COVER WILL HAVE A GREAT INFLUENCE ON TEMPERATURES WITH THE
OTHERWISE GOOD RADIATIONALLY COOLING NIGHT WITH LIGHT WINDS AND
PWATS AROUND 50 PERCENT OF NORMAL. THE REGIONAL GEM...WHICH USUALLY
DOES WELL IN THESE RADIATIONAL AND CLOUD SITUATIONS HAS LOWS AROUND
ZERO AROUND IRON COUNTY AND THAT COMBINED WITH THE PREVIOUS FORECAST
SEEMS LIKE THE WAY TO GO. UNFORTUNATELY IN THESE SITUATIONS...AN
HOUR OR TWO DIFFERENCE IN CLOUD COVER TIMING CAN EASILY BUST THE
FORECAST IN EITHER DIRECTION.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 447 AM EDT WED MAR 13 2013
UPPER AIR PATTERN CONSISTS OF A 500 MB RIDGE OVER THE WESTERN U.S.
WITH A TROUGH OVER THE EASTERN U.S. 12Z THU. THE RIDGE GETS
FLATTENED WITH TIME ON FRI WITH A SHORTWAVE MOVING INTO THE NORTHERN
PLAINS LATE FRI. NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE
AND DEEPER MOISTURE MOVING IN ON FRI AND FRI NIGHT.
FOR THIS FORECAST...NOT REAL CONFIDENT IN THE STORM SYSTEM FOR
FRIDAY FOR NOW. ECMWF AND GFS ARE TAKING THE SYSTEM A BIT FURTHER
SOUTH WHILE THE NAM IS NORTH WITH IT. NO REAL CONTINUITY IN THE
MODELS EITHER WITH THEIR FORECASTS...SO CONFIDENCE IS FAIRLY LOW.
WITH THE DIFFERENCE IN PLACEMENT OF THE SYSTEM...THIS WILL AFFECT
HOW COLD 850 MB TEMPERATURES ARE. 12Z ECMWF WAS MUCH WARMER AT 850
MB WITH TEMPERATURES OF -4C TO -8C ON FRI. 00Z ECMWF NOW IS COLDER
WITH 850 MB TEMPERATURES -8C TO -14C WHILE THE GFS IS -10C TO -12C.
WITH NORTH WINDS AND DELTA-T GREATER THAN 11C...THIS IS ENOUGH FOR
LAKE ENHANCEMENT OF THE SNOW. COULD SEE UP TO 5 INCHES OF SNOW ON
FRIDAY INTO FRIDAY NIGHT AND WILL PROBABLY NEED SOME HEADLINES UP
FOR FRIDAY AND FRIDAY NIGHT. WENT LIKELY POPS ON FRIDAY FOR THE LAKE
ENHANCEMENT. FOR THU...LOOKS LIKE A SYSTEM WILL STAY TO THE WEST OF
THE AREA AND ENDED UP GOING DRIER FOR THE FORECAST AS 850 MB
TEMPERATURES ARE NOT COLD ENOUGH FOR LAKE ENHANCEMENT.
OVERALL...LOWERED HIGH TEMPERATURES A COUPLE DEGREES ALONG WITH
OVERNIGHT LOWS DUE TO TRENDS LATELY WHERE FORECASTS HAVE BEEN TOO
WARM.
IN THE EXTENDED...GFS AND ECMWF SHOW A BROAD 500 MB TROUGH OVER THE
NORTHERN U.S. 12Z SAT. THIS TROUGH REMAINS OVER THE AREA ON SUN. A
TROUGH DIGS IN THE NORTHERN PLAINS ON MON AND AFFECTS THE UPPER
GREAT LAKES MON NIGHT INTO TUE. TEMPERATURES CONTINUE TO LOOK COLDER
THAN NORMAL THROUGH THE PERIOD WITH NO WARM UP IN SIGHT. WITH COLD
TEMPERATURES IN PLACE...LAKE EFFECT SNOW WILL BE POSSIBLE THIS
EXTENDED PERIOD FOR SAT AND SUNDAY. ANOTHER SYSTEM ARRIVES FOR MON
INTO TUE AND BRINGS A CHANCE FOR SNOW. THIS SYSTEM WILL HAVE TO BE
WATCHED AS COULD BE ANOTHER SIGNIFICANT WINTER STORM AND WILL HIT UP
THIS POTENTIAL IN THE HWO PRODUCT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 126 PM EDT WED MAR 13 2013
EXPECT PREDOMINANT VFR CONDITIONS AND SLOWLY DIMINISHING WINDS THIS
AFTN AS HI PRES RDG AXIS/AREA OF DRIER LLVL AIR MOVES SLOWLY EWD AND
PRES GRADIENT WEAKENS. NEXT CONCERN IS IMPACT OF AREA OF LLVL MSTR
THAT IS PRESENT OVER NW ONTARIO. NUMERICAL GUIDANCE SHOWS THIS MOIST
AIR STREAMING SEWD ACRS LK SUP AND INTO MAINLY NCENTRAL AND ERN UPR
MI IN THE NW FLOW AHEAD OF THE ENCROACHING HI. CONCERNED THERE COULD
BE SOME LK CLDS THAT FORM WITHIN THE CHILLY AIRMASS AFTER SUNSET
ESPECIALLY AT CMX/SAW...SO RETAINED FCST OF HI END MVFR CIGS BTWN
00Z-06Z AT CMX/SAW. AS THE HI PRES RDG MOVES CLOSER...EXPECT
SUBSIDENCE INVRN TO LOWER ENUF LATE TNGT TO DISSIPATE ANY MVFR CLDS
THAT DO FORM. ALTHOUGH SOME MID/HI CLDS WL INVADE THE AREA ON THU...
PREVAILING DRY LLVL AIR WL RESULT IN VFR CONDITIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 447 AM EDT WED MAR 13 2013
A SURFACE TROUGH THAT DROPPED SOUTH ACROSS LAKE SUPERIOR LAST NIGHT
WILL CONTINUE TO PRODUCE NORTHWEST WINDS OF 20-30KTS OVER THE
EASTERN LAKE TODAY. BUT WITH THE PARENT LOW MOVING NORTHEAST THROUGH
QUEBEC...THIS TIGHT PRESSURE GRADIENT WILL WEAKEN THIS AFTERNOON AS
HIGH PRESSURE MOVES OVER THE LAKE TONIGHT. WINDS HAVE DROPPED
BELOW GALES AT OBSERVATION SITES AND HAVE DROPPED THE GALE WARNING.
THERE COULD STILL BE A FEW GALE FORCE GUSTS OVER THE EASTERN LAKE
DURING THE MORNING...BUT THE COVERAGE SHOULD BE LIMITED. TONIGHT/S
HIGH WILL BEGIN TO SHIFT EAST ON THURSDAY...ALLOWING A COLD FRONT TO
DROP SOUTHEAST ACROSS LAKE SUPERIOR ON THURSDAY NIGHT. A SECONDARY
LOW PRESSURE SYSTEM WILL MOVE SOUTHEAST FROM THE UPPER MISSISSIPPI
VALLEY TO THE LOWER GREAT LAKES ON FRIDAY INTO FRIDAY
NIGHT...SHIFTING WINDS TO A NORTHERLY DIRECTION AT 15-30KTS. BEHIND
THIS LOW...A LARGE AREA OF HIGH PRESSURE WILL MOVE INTO THE UPPER
GREAT LAKES FOR SATURDAY. ANOTHER WEAK TROUGH WILL MOVE ACROSS LAKE
SUPERIOR ON SATURDAY NIGHT BEFORE THE HIGH PRESSURE RIDGE RESETS
OVER THE UPPER GREAT LAKES.
THERE WILL BE FREEZING SPRAY OVER CENTRAL AND EASTERN LAKE SUPERIOR
THROUGH THIS EVENING.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...07
AVIATION...KC
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
650 AM EDT WED MAR 13 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 447 AM EDT WED MAR 13 2013
WV IMAGERY AND RUC ANALYSIS UPPER TROUGH IS STILL ROTATING OVER THE
GREAT LAKES REGION THIS MORNING. THE ABUNDANT MOISTURE WITH THIS
UPPER LOW AND 850MB TEMPERATURES AROUND -16C LED TO MODERATE TO
HEAVY LAKE EFFECT SNOW OFF LAKE SUPERIOR YESTERDAY INTO THE
OVERNIGHT HOURS. AS OF 2AM...THE SNOWFALL TOTAL AT OUR OFFICE HAD
REACHED 8.7 INCHES. BUT MID LEVEL DRYING...SEEN ON THE 00Z KINL AND
CWPL SOUNDINGS ALONG WITH IR SATELLITE OVER WESTERN LAKE
SUPERIOR...HAD BROUGHT A QUICK END TO THE SNOW OVER THE WESTERN CWA
SHORTLY AFTER MIDNIGHT AND RECENT RADAR TRENDS OVER THE CENTRAL AND
EAST SHOW SIMILAR QUICK DECREASE.
UPPER RIDGE AND SURFACE HIGH PRESSURE WILL BE BUILDING IN TODAY AND
REMAINING INTO TONIGHT. THIS WILL CONTINUE TO PULL THE DRY AIR OVER
THE AREA AND SHOULD BRING AN END TO THE LINGERING SNOW SHOWERS OVER
THE EAST DURING THE MORNING HOURS. WITH THE QUICK DECREASE TO THE
SNOW...DECIDED TO DROP THE REMAINING WINTER WX ADVISORIES OVER THE
EAST. THE GUSTY WINDS TODAY WILL KEEP SOME BLOWING SNOW IN THE
FORECAST...WITH THE BEST CHANCES NEAR LAKE SUPERIOR EAST OF
MARQUETTE.
BASED ON LATEST TRENDS...HAVE OPTED TO GO MORE A LITTLE MORE
OPTIMISTIC ON THE CLOUD COVER FOR TODAY. THE QUICK TRANSITION TO
VFR AND MID CLOUDS OVER THE WEST SHOWS A LACK OF LOW LEVEL MOISTURE
EVENTHOUGH 850MB TEMPS ARE STILL AROUND -14C. THERE IS JUST ENOUGH
TERRAIN ENHANCEMENT TO AID CLOUD COVER OVER THE WEST AND THAT COULD
BE THE CASE TODAY...ESPECIALLY WITH SOME DIURNAL HEATING HELP.
THUS...AFTER THE DEEPER MOISTURE DEPARTS THIS
MORNING...TRANSITIONED TO A PARTLY CLOUDY SKY WITH THE GREATEST
CLEARING NEAR THE WISCONSIN BORDER. HIGHS TODAY WILL REMAIN BELOW
NORMAL WITH MOST LOCATIONS IN THE MID-UPPER 20S.
FOR TONIGHT...MODELS STILL HINTING AT A INCREASE IN THE MOISTURE IN
THE 925-875MB RANGE LATE THIS AFTERNOON INTO THIS EVENING FROM THE
KEWEENAW SOUTHEAST THROUGH MARQUETTE/ALGER COUNTIES. 875MB TEMPS
AROUND -12.5C WOULD SUPPORT ENOUGH INSTABILITY FOR SOME SNOW
SHOWERS...BUT CONCERN IS THE DEPTH OF THE CLOUD LAYER WHICH WILL
LIKELY ONLY BE 2-3KFT. THERE WAS A THIN AREA OF CLOUDS THIS PAST
EVENING WHERE THE MODELS ARE SHOWING THE LOW MOISTURE...BUT IT HAS
SINCE DISSIPATED. THAT MOISTURE MAY STILL BE PRESENT AND WITH THE
INFLUENCE OF LAKE SUPERIOR...PUT IN A MENTION OF ISOLATED
FLURRIES FOR ALGER/LUCE/SCHOOLCRAFT COUNTIES.
OTHERWISE...HIGH PRESSURE SHOULD BE IN PLACE OVER THE AREA AND LEAD
TO A QUIET NIGHT. THE WESTERN CWA WILL LIKELY BE MOSTLY CLEAR
DURING THE EVENING HOURS BEFORE MID/HIGH CLOUDS START STREAMING IN
AHEAD OF THE NEXT SHORTWAVE DROPPING THROUGH THE NORTHWEST FLOW
ALOFT. THINKING THE HIGH CLOUDS WILL BE IN BY MIDNIGHT AND THEN
THEY WILL THICKEN/LOWER THROUGH THE NIGHT AND COVER ALL OF THE
WESTERN CWA BY MORNING. THIS GIVES CONCERN TO LOWS FOR TONIGHT...AS
THE CLOUD COVER WILL HAVE A GREAT INFLUENCE ON TEMPERATURES WITH THE
OTHERWISE GOOD RADIATIONALLY COOLING NIGHT WITH LIGHT WINDS AND
PWATS AROUND 50 PERCENT OF NORMAL. THE REGIONAL GEM...WHICH USUALLY
DOES WELL IN THESE RADIATIONAL AND CLOUD SITUATIONS HAS LOWS AROUND
ZERO AROUND IRON COUNTY AND THAT COMBINED WITH THE PREVIOUS FORECAST
SEEMS LIKE THE WAY TO GO. UNFORTUNATELY IN THESE SITUATIONS...AN
HOUR OR TWO DIFFERENCE IN CLOUD COVER TIMING CAN EASILY BUST THE
FORECAST IN EITHER DIRECTION.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 447 AM EDT WED MAR 13 2013
UPPER AIR PATTERN CONSISTS OF A 500 MB RIDGE OVER THE WESTERN U.S.
WITH A TROUGH OVER THE EASTERN U.S. 12Z THU. THE RIDGE GETS
FLATTENED WITH TIME ON FRI WITH A SHORTWAVE MOVING INTO THE NORTHERN
PLAINS LATE FRI. NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE
AND DEEPER MOISTURE MOVING IN ON FRI AND FRI NIGHT.
FOR THIS FORECAST...NOT REAL CONFIDENT IN THE STORM SYSTEM FOR
FRIDAY FOR NOW. ECMWF AND GFS ARE TAKING THE SYSTEM A BIT FURTHER
SOUTH WHILE THE NAM IS NORTH WITH IT. NO REAL CONTINUITY IN THE
MODELS EITHER WITH THEIR FORECASTS...SO CONFIDENCE IS FAIRLY LOW.
WITH THE DIFFERENCE IN PLACEMENT OF THE SYSTEM...THIS WILL AFFECT
HOW COLD 850 MB TEMPERATURES ARE. 12Z ECMWF WAS MUCH WARMER AT 850
MB WITH TEMPERATURES OF -4C TO -8C ON FRI. 00Z ECMWF NOW IS COLDER
WITH 850 MB TEMPERATURES -8C TO -14C WHILE THE GFS IS -10C TO -12C.
WITH NORTH WINDS AND DELTA-T GREATER THAN 11C...THIS IS ENOUGH FOR
LAKE ENHANCEMENT OF THE SNOW. COULD SEE UP TO 5 INCHES OF SNOW ON
FRIDAY INTO FRIDAY NIGHT AND WILL PROBABLY NEED SOME HEADLINES UP
FOR FRIDAY AND FRIDAY NIGHT. WENT LIKELY POPS ON FRIDAY FOR THE LAKE
ENHANCEMENT. FOR THU...LOOKS LIKE A SYSTEM WILL STAY TO THE WEST OF
THE AREA AND ENDED UP GOING DRIER FOR THE FORECAST AS 850 MB
TEMPERATURES ARE NOT COLD ENOUGH FOR LAKE ENHANCEMENT.
OVERALL...LOWERED HIGH TEMPERATURES A COUPLE DEGREES ALONG WITH
OVERNIGHT LOWS DUE TO TRENDS LATELY WHERE FORECASTS HAVE BEEN TOO
WARM.
IN THE EXTENDED...GFS AND ECMWF SHOW A BROAD 500 MB TROUGH OVER THE
NORTHERN U.S. 12Z SAT. THIS TROUGH REMAINS OVER THE AREA ON SUN. A
TROUGH DIGS IN THE NORTHERN PLAINS ON MON AND AFFECTS THE UPPER
GREAT LAKES MON NIGHT INTO TUE. TEMPERATURES CONTINUE TO LOOK COLDER
THAN NORMAL THROUGH THE PERIOD WITH NO WARM UP IN SIGHT. WITH COLD
TEMPERATURES IN PLACE...LAKE EFFECT SNOW WILL BE POSSIBLE THIS
EXTENDED PERIOD FOR SAT AND SUNDAY. ANOTHER SYSTEM ARRIVES FOR MON
INTO TUE AND BRINGS A CHANCE FOR SNOW. THIS SYSTEM WILL HAVE TO BE
WATCHED AS COULD BE ANOTHER SIGNIFICANT WINTER STORM AND WILL HIT UP
THIS POTENTIAL IN THE HWO PRODUCT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 649 AM EDT WED MAR 13 2013
SYSTEM THAT HAS BROUGHT THE SNOW TO THE AREA OVER THE LAST COUPLE
OF DAYS AS STARTED TO EXIT AND DRIER AIR HAS SURGED SOUTH ACROSS
LAKE SUPERIOR. THIS SHOULD LEAD TO VFR CONDITIONS FOR MUCH OF THE
FORECAST PERIOD. THERE ARE A COUPLE ITEMS TO NOTE THOUGH.
FIRST...THERE WILL STILL BE GUSTY WINDS THROUGH THE EARLY
AFTERNOON...ESPECIALLY AT KSAW. THIS COULD PRODUCE A SOME BLOWING
SNOW...BUT LEFT VISIBILITY RESTRICTIONS OUT OF THE TAF.
SECOND...MODELS ARE SHOWING A POCKET OF LOWER LEVEL MOISTURE MOVING
SOUTHEAST ACROSS LAKE SUPERIOR LATE THIS AFTERNOON AND INTO THE
EVENING HOURS. CONFIDENCE IS LIMITED ON THIS OCCURRING WITH THE
LACK OF CLOUDS UPSTREAM...BUT DID PUT A MENTION OF BORDERLINE MVFR
CEILINGS FOR KCMX/KSAW. FINALLY...A SHORTWAVE WILL BE MOVING
THROUGH WISCONSIN TOMORROW...WHICH WILL SPREAD MID CLOUDS OVER THE
AREA AND COULD BRUSH KIWD WITH -SHSN AT THE END OR JUST AFTER THE
TAF PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 447 AM EDT WED MAR 13 2013
A SURFACE TROUGH THAT DROPPED SOUTH ACROSS LAKE SUPERIOR LAST NIGHT
WILL CONTINUE TO PRODUCE NORTHWEST WINDS OF 20-30KTS OVER THE
EASTERN LAKE TODAY. BUT WITH THE PARENT LOW MOVING NORTHEAST THROUGH
QUEBEC...THIS TIGHT PRESSURE GRADIENT WILL WEAKEN THIS AFTERNOON AS
HIGH PRESSURE MOVES OVER THE LAKE TONIGHT. WINDS HAVE DROPPED
BELOW GALES AT OBSERVATION SITES AND HAVE DROPPED THE GALE WARNING.
THERE COULD STILL BE A FEW GALE FORCE GUSTS OVER THE EASTERN LAKE
DURING THE MORNING...BUT THE COVERAGE SHOULD BE LIMITED. TONIGHT/S
HIGH WILL BEGIN TO SHIFT EAST ON THURSDAY...ALLOWING A COLD FRONT TO
DROP SOUTHEAST ACROSS LAKE SUPERIOR ON THURSDAY NIGHT. A SECONDARY
LOW PRESSURE SYSTEM WILL MOVE SOUTHEAST FROM THE UPPER MISSISSIPPI
VALLEY TO THE LOWER GREAT LAKES ON FRIDAY INTO FRIDAY
NIGHT...SHIFTING WINDS TO A NORTHERLY DIRECTION AT 15-30KTS. BEHIND
THIS LOW...A LARGE AREA OF HIGH PRESSURE WILL MOVE INTO THE UPPER
GREAT LAKES FOR SATURDAY. ANOTHER WEAK TROUGH WILL MOVE ACROSS LAKE
SUPERIOR ON SATURDAY NIGHT BEFORE THE HIGH PRESSURE RIDGE RESETS
OVER THE UPPER GREAT LAKES.
THERE WILL BE FREEZING SPRAY OVER CENTRAL AND EASTERN LAKE SUPERIOR
THROUGH THIS EVENING.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...07
AVIATION...SRF
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
449 AM EDT WED MAR 13 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 447 AM EDT WED MAR 13 2013
WV IMAGERY AND RUC ANALYSIS UPPER TROUGH IS STILL ROTATING OVER THE
GREAT LAKES REGION THIS MORNING. THE ABUNDANT MOISTURE WITH THIS
UPPER LOW AND 850MB TEMPERATURES AROUND -16C LED TO MODERATE TO
HEAVY LAKE EFFECT SNOW OFF LAKE SUPERIOR YESTERDAY INTO THE
OVERNIGHT HOURS. AS OF 2AM...THE SNOWFALL TOTAL AT OUR OFFICE HAD
REACHED 8.7 INCHES. BUT MID LEVEL DRYING...SEEN ON THE 00Z KINL AND
CWPL SOUNDINGS ALONG WITH IR SATELLITE OVER WESTERN LAKE
SUPERIOR...HAD BROUGHT A QUICK END TO THE SNOW OVER THE WESTERN CWA
SHORTLY AFTER MIDNIGHT AND RECENT RADAR TRENDS OVER THE CENTRAL AND
EAST SHOW SIMILAR QUICK DECREASE.
UPPER RIDGE AND SURFACE HIGH PRESSURE WILL BE BUILDING IN TODAY AND
REMAINING INTO TONIGHT. THIS WILL CONTINUE TO PULL THE DRY AIR OVER
THE AREA AND SHOULD BRING AN END TO THE LINGERING SNOW SHOWERS OVER
THE EAST DURING THE MORNING HOURS. WITH THE QUICK DECREASE TO THE
SNOW...DECIDED TO DROP THE REMAINING WINTER WX ADVISORIES OVER THE
EAST. THE GUSTY WINDS TODAY WILL KEEP SOME BLOWING SNOW IN THE
FORECAST...WITH THE BEST CHANCES NEAR LAKE SUPERIOR EAST OF
MARQUETTE.
BASED ON LATEST TRENDS...HAVE OPTED TO GO MORE A LITTLE MORE
OPTIMISTIC ON THE CLOUD COVER FOR TODAY. THE QUICK TRANSITION TO
VFR AND MID CLOUDS OVER THE WEST SHOWS A LACK OF LOW LEVEL MOISTURE
EVENTHOUGH 850MB TEMPS ARE STILL AROUND -14C. THERE IS JUST ENOUGH
TERRAIN ENHANCEMENT TO AID CLOUD COVER OVER THE WEST AND THAT COULD
BE THE CASE TODAY...ESPECIALLY WITH SOME DIURNAL HEATING HELP.
THUS...AFTER THE DEEPER MOISTURE DEPARTS THIS
MORNING...TRANSITIONED TO A PARTLY CLOUDY SKY WITH THE GREATEST
CLEARING NEAR THE WISCONSIN BORDER. HIGHS TODAY WILL REMAIN BELOW
NORMAL WITH MOST LOCATIONS IN THE MID-UPPER 20S.
FOR TONIGHT...MODELS STILL HINTING AT A INCREASE IN THE MOISTURE IN
THE 925-875MB RANGE LATE THIS AFTERNOON INTO THIS EVENING FROM THE
KEWEENAW SOUTHEAST THROUGH MARQUETTE/ALGER COUNTIES. 875MB TEMPS
AROUND -12.5C WOULD SUPPORT ENOUGH INSTABILITY FOR SOME SNOW
SHOWERS...BUT CONCERN IS THE DEPTH OF THE CLOUD LAYER WHICH WILL
LIKELY ONLY BE 2-3KFT. THERE WAS A THIN AREA OF CLOUDS THIS PAST
EVENING WHERE THE MODELS ARE SHOWING THE LOW MOISTURE...BUT IT HAS
SINCE DISSIPATED. THAT MOISTURE MAY STILL BE PRESENT AND WITH THE
INFLUENCE OF LAKE SUPERIOR...PUT IN A MENTION OF ISOLATED
FLURRIES FOR ALGER/LUCE/SCHOOLCRAFT COUNTIES.
OTHERWISE...HIGH PRESSURE SHOULD BE IN PLACE OVER THE AREA AND LEAD
TO A QUIET NIGHT. THE WESTERN CWA WILL LIKELY BE MOSTLY CLEAR
DURING THE EVENING HOURS BEFORE MID/HIGH CLOUDS START STREAMING IN
AHEAD OF THE NEXT SHORTWAVE DROPPING THROUGH THE NORTHWEST FLOW
ALOFT. THINKING THE HIGH CLOUDS WILL BE IN BY MIDNIGHT AND THEN
THEY WILL THICKEN/LOWER THROUGH THE NIGHT AND COVER ALL OF THE
WESTERN CWA BY MORNING. THIS GIVES CONCERN TO LOWS FOR TONIGHT...AS
THE CLOUD COVER WILL HAVE A GREAT INFLUENCE ON TEMPERATURES WITH THE
OTHERWISE GOOD RADIATIONALLY COOLING NIGHT WITH LIGHT WINDS AND
PWATS AROUND 50 PERCENT OF NORMAL. THE REGIONAL GEM...WHICH USUALLY
DOES WELL IN THESE RADIATIONAL AND CLOUD SITUATIONS HAS LOWS AROUND
ZERO AROUND IRON COUNTY AND THAT COMBINED WITH THE PREVIOUS FORECAST
SEEMS LIKE THE WAY TO GO. UNFORTUNATELY IN THESE SITUATIONS...AN
HOUR OR TWO DIFFERENCE IN CLOUD COVER TIMING CAN EASILY BUST THE
FORECAST IN EITHER DIRECTION.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 447 AM EDT WED MAR 13 2013
UPPER AIR PATTERN CONSISTS OF A 500 MB RIDGE OVER THE WESTERN U.S.
WITH A TROUGH OVER THE EASTERN U.S. 12Z THU. THE RIDGE GETS
FLATTENED WITH TIME ON FRI WITH A SHORTWAVE MOVING INTO THE NORTHERN
PLAINS LATE FRI. NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE
AND DEEPER MOISTURE MOVING IN ON FRI AND FRI NIGHT.
FOR THIS FORECAST...NOT REAL CONFIDENT IN THE STORM SYSTEM FOR
FRIDAY FOR NOW. ECMWF AND GFS ARE TAKING THE SYSTEM A BIT FURTHER
SOUTH WHILE THE NAM IS NORTH WITH IT. NO REAL CONTINUITY IN THE
MODELS EITHER WITH THEIR FORECASTS...SO CONFIDENCE IS FAIRLY LOW.
WITH THE DIFFERENCE IN PLACEMENT OF THE SYSTEM...THIS WILL AFFECT
HOW COLD 850 MB TEMPERATURES ARE. 12Z ECMWF WAS MUCH WARMER AT 850
MB WITH TEMPERATURES OF -4C TO -8C ON FRI. 00Z ECMWF NOW IS COLDER
WITH 850 MB TEMPERATURES -8C TO -14C WHILE THE GFS IS -10C TO -12C.
WITH NORTH WINDS AND DELTA-T GREATER THAN 11C...THIS IS ENOUGH FOR
LAKE ENHANCEMENT OF THE SNOW. COULD SEE UP TO 5 INCHES OF SNOW ON
FRIDAY INTO FRIDAY NIGHT AND WILL PROBABLY NEED SOME HEADLINES UP
FOR FRIDAY AND FRIDAY NIGHT. WENT LIKELY POPS ON FRIDAY FOR THE LAKE
ENHANCEMENT. FOR THU...LOOKS LIKE A SYSTEM WILL STAY TO THE WEST OF
THE AREA AND ENDED UP GOING DRIER FOR THE FORECAST AS 850 MB
TEMPERATURES ARE NOT COLD ENOUGH FOR LAKE ENHANCEMENT.
OVERALL...LOWERED HIGH TEMPERATURES A COUPLE DEGREES ALONG WITH
OVERNIGHT LOWS DUE TO TRENDS LATELY WHERE FORECASTS HAVE BEEN TOO
WARM.
IN THE EXTENDED...GFS AND ECMWF SHOW A BROAD 500 MB TROUGH OVER THE
NORTHERN U.S. 12Z SAT. THIS TROUGH REMAINS OVER THE AREA ON SUN. A
TROUGH DIGS IN THE NORTHERN PLAINS ON MON AND AFFECTS THE UPPER
GREAT LAKES MON NIGHT INTO TUE. TEMPERATURES CONTINUE TO LOOK COLDER
THAN NORMAL THROUGH THE PERIOD WITH NO WARM UP IN SIGHT. WITH COLD
TEMPERATURES IN PLACE...LAKE EFFECT SNOW WILL BE POSSIBLE THIS
EXTENDED PERIOD FOR SAT AND SUNDAY. ANOTHER SYSTEM ARRIVES FOR MON
INTO TUE AND BRINGS A CHANCE FOR SNOW. THIS SYSTEM WILL HAVE TO BE
WATCHED AS COULD BE ANOTHER SIGNIFICANT WINTER STORM AND WILL HIT UP
THIS POTENTIAL IN THE HWO PRODUCT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 130 AM EDT WED MAR 13 2013
WITH DISTURBANCE/TROF EXITING...DRIER AIR IS FLOWING INTO THE
AREA...RESULTING IN MUCH IMPROVED CONDITIONS FROM EARLIER IN THE
NIGHT. AT KIWD/KCMX/KSAW...MVFR/VFR CONDITIONS SHOULD PREVAIL OVERNIGHT.
SOME LINGERING SHSN ARE POSSIBLE FOR THE NEXT FEW HRS AT KSAW...BUT
SHOULD ONLY RESULT IN BRIEF REDUCTION OF VIS BLO MVFR. WITH CONTINUED
DRYING...MVFR CIGS SHOULD TEND TO SCATTER OUT TODAY OR LIFT JUST
ABOVE 3KFT...AND THAT COULD HAPPEN AS EARLY AS THE MORNING HRS. VFR
CONDITIONS WILL ROUND OUT THE FCST DURING THE EVENING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 447 AM EDT WED MAR 13 2013
A SURFACE TROUGH THAT DROPPED SOUTH ACROSS LAKE SUPERIOR LAST NIGHT
WILL CONTINUE TO PRODUCE NORTHWEST WINDS OF 20-30KTS OVER THE
EASTERN LAKE TODAY. BUT WITH THE PARENT LOW MOVING NORTHEAST THROUGH
QUEBEC...THIS TIGHT PRESSURE GRADIENT WILL WEAKEN THIS AFTERNOON AS
HIGH PRESSURE MOVES OVER THE LAKE TONIGHT. WINDS HAVE DROPPED
BELOW GALES AT OBSERVATION SITES AND HAVE DROPPED THE GALE WARNING.
THERE COULD STILL BE A FEW GALE FORCE GUSTS OVER THE EASTERN LAKE
DURING THE MORNING...BUT THE COVERAGE SHOULD BE LIMITED. TONIGHT/S
HIGH WILL BEGIN TO SHIFT EAST ON THURSDAY...ALLOWING A COLD FRONT TO
DROP SOUTHEAST ACROSS LAKE SUPERIOR ON THURSDAY NIGHT. A SECONDARY
LOW PRESSURE SYSTEM WILL MOVE SOUTHEAST FROM THE UPPER MISSISSIPPI
VALLEY TO THE LOWER GREAT LAKES ON FRIDAY INTO FRIDAY
NIGHT...SHIFTING WINDS TO A NORTHERLY DIRECTION AT 15-30KTS. BEHIND
THIS LOW...A LARGE AREA OF HIGH PRESSURE WILL MOVE INTO THE UPPER
GREAT LAKES FOR SATURDAY. ANOTHER WEAK TROUGH WILL MOVE ACROSS LAKE
SUPERIOR ON SATURDAY NIGHT BEFORE THE HIGH PRESSURE RIDGE RESETS
OVER THE UPPER GREAT LAKES.
THERE WILL BE FREEZING SPRAY OVER CENTRAL AND EASTERN LAKE SUPERIOR
THROUGH THIS EVENING.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...07
AVIATION...ROLFSON/SRF
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
133 AM EDT WED MAR 13 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 408 PM EDT TUE MAR 12 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF
CENTERED OVER THE GREAT LKS BTWN UPR RDGS ALONG THE W COAST AND OFF
THE E COAST. WITH DEEP CYC NW FLOW...ABUNDANT MSTR SHOWN ON THE 12Z
GRB RAOB...AND H85 TEMPS IN THE -13C TO -16C RANGE...SHSN HAVE BEEN
COMMON OVER THE CWA TODAY UNDER CLDY SKIES...ESPECIALLY NEAR LK SUP
IN AREAS FAVORED BY THE NW LLVL FLOW. THE SN HAS BEEN RATHER FLUFFY
AS MODEL SDNGS INDICATE THE DGZ IS SEVERAL THOUSAND FEET DEEP GIVEN
FVRBL H85 TEMPS. THERE IS A SHRTWV DROPPING SEWD THRU MN ACCOMPANIED
BY A FAIRLY WELL DEFINED TROF AT H85-7. UPSTREAM OBS AT GRAND MARAIS
ON THE MN NORTH SHORE AND AT THUNDER BAY IN ONTARIO INDICATE SOME
HEAVIER SHSN ACCOMPANY THIS TROF PASSAGE FARTHER TO THE E-SE AWAY FM
DRIER AIR SHOWN ON THE 12Z INL/YPL RAOBS. APRCHG FCST ISSUANCE...
SOME OF THE HEAVIER SHSN HAVE ARRIVED OVER THE WRN COUNTIES. CMX HAS
REPORTED VSBY DOWN TO 1/4SM AT TIMES...AND REPORTS FM GOGEBIC COUNTY
INDICATE AS MUCH AS 5 INCHES OF SN FELL THERE THRU 18Z.
LATE THIS AFTN/TNGT...AS SHRTWV IN MN DIGS SEWD...GUIDANCE SHOWS
PRONOUNCED H85 WSHFT ASSOCIATED WITH TROF PASSAGE AS WELL AS AREA OF
H85-5 QVECTOR CNVGC CROSSING THE CWA NW-SE. EXPECT SHSN TO INCRS IN
INTENSITY WITH THIS ENHANCED SUPPORT IN PRESENCE OF DEEP MSTR. FCST
SDNGS CONTINUE TO SHOW UVV FOCUSED IN THE DGZ...SO EXPECT HI SN/
WATER RATIOS AOA 20:1. LATER TNGT IN THE WAKE OF THE TROF PASSAGE...
DEEP LYR QVECTOR DVGC/SUBSIDENCE IN THE WAKE OF THE SHRTWV/TROF WL
CONSPIRE TO LOWER INVRN BASES DOWN TO 2-3K FT AGL. WITH ARRIVAL OF
LLVL DRY AIR SHOWN ON THE 12Z INL/YPL RAOBS...EXPECT LES TO DIMINISH
FAIRLY STEADILY AFT 06Z. OVERALL...SHIFTING WINDS FM NW TO N AND
LIMITED 6-9HR WINDOW OR SO FOR HEAVIER SHSN WL LIMIT TOTAL SN
FALL...SO EXPECT SN TOTALS TO REMAIN WITHIN ADVY LIMITS DESPITE
FVRBL SN/WATER RATIOS. THGE ONLY EXCEPTION IS OVER THE FAR W...WHERE
SOME HEAVY SN FELL DURING THE AFTN AS NOTED ABV. SINCE THERE WL BE
PERIODS OF +SHSN THRU THIS EVNG IN THAT AREA WITH SOME FOCUSED LLVL
CNVGC IN FVRBL CYC NNW FLOW...OPTED TO UPGRADE ADVY TO A WARNING FOR
GOGEBIC/ONTONAGON COUNTIES. ALSO EXTENDED ADVY OVER THE ERN ZNS THRU
12Z GIVEN MORE PERSISTENT FORCING/DEEPER MSTR THERE.
WED...AXIS OF MUCH DRIER AIR WITH H85 DEWPTS AS LO AS -40C AS WELL
AS DEEP LYR QVECTOR DVGC/SUBSIDENCE UNDER STEADILY RISING H5 HGTS
FOLLOWING SHIFT OF UPR TROF AXIS TO THE E WL RESULT IN MAINLY DRY WX
AFTER LINGERING SHSN OVER MAINLY THE E DIMINISH IN THE MRNG. IN
FACT...FCST SDNGS SUG SKIES MAY TURN MOSUNNY IN THE AFTN...
ESPECIALLY NEAR LK SUP WITH A TENDENCY FOR CLRG OVER THE WATER UNDER
STRENGTHENING LATE WINTER SUNSHINE.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 408 PM EDT TUE MAR 12 2013
TO START THE LONG TERM PERIOD...OVERVIEW OF LARGE SCALE FEATURES
TROUGH OVER GREAT LAKES AND EASTERN CANADA WITH BROAD RIDGING
EXTENDING WELL UPSTREAM INTO EASTERN PORTION OF PACIFIC OCEAN.
FARTHER UPSTREAM TROUGHING IS PRESENT NORTH OF HAWAII. THAT TROUGH
IS ESSENTIALLY EXTENSION OF TROUGHING RESIDING OVER NORTHERN
PORTIONS OF CANADA ON NORTHERN PORTION OF WESTERN CONUS RIDGE. OVER
TIME...TROUGH OVER GREAT LAKES SYNCS UP WITH TROUGHING OVER NORTHERN
CANADA RESULTING IN FAST AND ACTIVE WEST-NORTHWEST FLOW ACROSS
MOST OF THE CONUS THROUGH THE UPCOMING WEEKEND.
TWO SHORTWAVES PROGGED TO DROP THROUGH IN THIS FLOW PATTERN INTO
THIS WEEKEND. FIRST WAVE ALONG WITH WEAK SFC-H85 LOW-LEVEL WARM AIR
ADVECTION GLANCES UPR LAKES TO WEST ON THURSDAY. WAVE IS DIGGING
INTO THE MEAN TROUGH WHICH FAVORS MORE OF A SOUTH AND/OR WEST TRACK
AND IS PRETTY PROGRESSIVE. ALSO LOOKS LIKE ANY UPPER JET SUPPORT
REMAINS WEST OF UPR MICHIGAN. MODELS VARY WILDLY FROM SOUTH TO NORTH
WHERE THE MOST QPF/SNOW IS EXPECTED. GEM-NH ON SOUTHERN EXTREME...
TRACKING ACROSS IOWA...WHILE NAM IS OVER WESTERN UPR MICHIGAN. NAM
IS ON NORTH EDGE OF EVEN SREF...SO IT IS CERTAINLY AN OUTLIER. GFS
AND ECMWF IN BTWN...BUT ARE STILL MAINLY OVER WISCONSIN. SINCE THERE
IS A SLIGHT EASTWARD TREND IN MODELS...WILL BRING CHANCE POPS OVER
WESTERN CWA ON THURSDAY. OTHER ISSUE...PREVIOUSLY MENTIONED BY MID
SHIFT...IS POSSIBLE FREEZING DRIZZLE LATER THURSDAY INTO THURSDAY
NIGHT. BASED ON FORECAST SOUNDINGS...WI BORDER/SCNTRL...WILL HAVE
BEST CHANCE SEEING THIS ONCE ANY SNOW DECREASES. ELSEWHERE...THINK
TOO MUCH DRIER AIR IS AROUND BLO H85 TO HAVE IN THERE. SINCE AM NOT
CERTAIN WHERE ULTIMATELY THE STEADIER SNOW SETS UP OVR CWA...IF IT
DOES AT ALL...WILL KEEP FZDZ OUT OF FCST.
COUPLE OF SUBTLE THINGS HAPPEN LATER THURSDAY INTO THURSDAY NIGHT
THAT MAY HAVE LARGE IMPACT ON FORECAST FOR FRIDAY. ALL MODELS INDICATE
STRONGER NORTHERN STREAM WAVE TRACKS WELL TO THE NORTH OVER NORTHWEST
ONTARIO THURSDAY NIGHT. WE ARE GOOD THERE. TROUBLE IS THAT SAME
MODELS DIFFER ON HOW FAR SOUTH TO BRING LOW-LEVEL COLD AIR IN WAKE OF
SHORTWAVE BY FRIDAY MORNING. GEM-NH FARTHER SOUTH WITH COLD AIR AND
TRENDS FROM GFS ALSO INDICATE FARTHER SOUTH LOW-LEVEL TEMPERATURE
GRADIENT AT SFC-H85. ECMWF NOT AS COLD THOUGH. LOCATION OF TIGHTER
LOW-LEVEL TEMPERATURE GRADIENT COULD PAVE THE WAY FOR WHERE HEAVIER
QPF/SNOW SETS UP ON FRIDAY AS SHORTWAVE AND SFC-H85 LOWS MOVE IN FROM
NORTHERN PLAINS.
THIS SECOND SHORTWAVE IS MUCH STRONGER THAN ONE MOVING THROUGH 24 HR
EARLIER AND HAS POTENTIAL TO BRING WIDESRPEAD SNOW TO UPPER LAKES ON
FRIDAY. WHERE EVER LOW-LEVEL BAROCLINIC ZONE SETS UP THERE ARE
ENHANCING FACTORS THAT MAY RESULT IN SWATH OF MODERATE TO HEAVY SNOW
INCLUDING DIVERGENCE ALOFT FROM RIGHT ENTRANCE REGION OF JET STREAK
DROPPING INTO GREAT LAKES FROM ONTARIO...DECENT MOISTURE ADVECTION
WITH H7 MIXING RATIOS OVR 3G/KG...AND OVERALL STRENGTHENING SFC-H85
LOWS/LOW-LEVEL FLOW. ADVY LEVEL SNOWS CERTAINLY POSSIBLE. INCREASED
POPS TO LIKELY OVER WEST AND SOUTH...WHERE MODEL AGREEMENT IS HIGHER
THAT SNOW OCCURS. WWD DAY 3 GRAPHICS INDICATE UP TO 4 INCHES OVER
WEST THIRD OF CWA ON FRIDAY. IF FARTHER NORTH ECMWF AND GEM-NH ARE
CORRECT...THEN LIKELY POPS WILL BE NEEDED FOR MOST AREAS ON FRIDAY.
AT FIRST GLANCE A MAINLY QUIET WEEKEND AS HIGH PRESSURE IS MAIN
FEATURE OVER REGION. COULD BE RE-INFORCING SHOT OF COLDER AIR AND
SOME DEEPER MOISTURE COME IN LATER SATURDAY AND SATURDAY NIGHT.
GFS/ECMWF INDICATE INCREASE IN POPS DURING THAT TIME. KEPT CHANCY
POPS IN ALONG LK SUPERIOR WITH ADDED POTENTIAL FOR LK EFFECT AS H85
TEMPS DROP INTO THE -15C TO -20C RANGE. RECORD SETTING WARMTH OF MID
MARCH IN 2012 WILL BE BUT A DISTANT MEMORY COMPARED TO THE CHILL OF
THIS YEAR.
COOL AND ACTIVE PATTERN CONTINUES INTO EARLY NEXT WEEK...AND
PROBABLY EVEN INTO LATER MARCH AS WELL. CERTAINLY NOT DONE WITH
WINTER YET. DEEPER SHORTWAVE TROUGH EMERGES FROM TROUGHING OVER
NORTHERN CANADA AND EVENTUALLY TRACKS ACROSS ROCKIES LATE IN THE
WEEKEND. THIS TROUGH THEN DEEPENS ACROSS THE MIDDLE CONUS MONDAY AND
MOVES INTO THE GREAT LAKES ON TUESDAY. DEEPENING LOW PRESSURE SYSTEM
RESULTS WHICH DRAWS UP GULF MOISTURE AND COULD LEAD TO SIGNIFICANT
SNOW SOMEWHERE UPPER MIDWEST THROUGH THE GREAT LAKES...INCLUDING UPR
MICHIGAN. OVERALL THE ECMWF IS DEEPER AND FARTHER NORTH WITH SFC
LOW...THOUGH LATEST RUN BACKED OFF WITH STRENGTH OF LOW. GFS IS MORE
SUPPRESSED WITH TRACK OF SFC LOW. WPC...FORMALLY HPC...HAND DRAWN
PROGS BTWN THE TWO WITH LOW MOVING ACROSS LOWER LAKES AND UPR
MICHIGAN JUST ON THE FRINGE. CONSENSUS POPS ARE IN THE CHANCE RANGE
WHICH IS FINE AT THIS POINT. GIVEN NORTHEAST WINDS AND COOLER
AIR...INCREASED POPS CLOSER TO LK SUPERIOR.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 130 AM EDT WED MAR 13 2013
WITH DISTURBANCE/TROF EXITING...DRIER AIR IS FLOWING INTO THE
AREA...RESULTING IN MUCH IMPROVED CONDITIONS FROM EARLIER IN THE
NIGHT. AT KIWD/KCMX/KSAW...MVFR/VFR CONDITIONS SHOULD PREVAIL OVERNIGHT.
SOME LINGERING SHSN ARE POSSIBLE FOR THE NEXT FEW HRS AT KSAW...BUT
SHOULD ONLY RESULT IN BRIEF REDUCTION OF VIS BLO MVFR. WITH CONTINUED
DRYING...MVFR CIGS SHOULD TEND TO SCATTER OUT TODAY OR LIFT JUST
ABOVE 3KFT...AND THAT COULD HAPPEN AS EARLY AS THE MORNING HRS. VFR
CONDITIONS WILL ROUND OUT THE FCST DURING THE EVENING.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 408 PM EDT TUE MAR 12 2013
UNDER THE TIGHTENING PRES GRADIENT IN THE WAKE OF A TROF PASSAGE
THIS EVENING...EXPECT A N GALE UP TO 35 KTS OVER PORTIONS OF
NCENTRAL LAKE SUP MUCH OF TONIGHT. FREEZING SPRAY WILL BE
WIDESPREAD. AS THE GRADIENT WEAKENS LATE TONIGHT THRU WED...THE
WINDS WILL GRADUALLY DIMINISH AND BACK TOWARD THE NW WITH APPROACH
OF HI PRES FROM THE W. WINDS OF LESS THAN 20 KTS PERSIST INTO
THURSDAY AS HIGH PRESSURE SLIDES ACROSS. SOUTHWESTERLY RETURN FLOW
ON BACK SIDE OF HIGH MAY GET GUSTY OVER 25 KTS BY THU NIGHT. COLD
FRONT SHIFTS THROUGH OVERNIGHT THURSDAY NIGHT WITH NORTHWEST WINDS
TRYING TO REACH 30 KTS. NORTHERLY WINDS TO 25 KTS CONTINUE INTO FRI.
WINDS DIMINISH THROUGH REST OF WEEKEND AS HIGH PRESSURE RETURNS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL 8 AM EDT THIS MORNING FOR MIZ006-
007-085.
LAKE EFFECT SNOW WARNING UNTIL 2 AM EDT /1 AM CDT/ EARLY THIS
MORNING FOR MIZ002-009.
WINTER WEATHER ADVISORY UNTIL 2 AM EDT EARLY THIS MORNING FOR
MIZ001-003-004-084.
WINTER WEATHER ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
MIZ005.
LAKE SUPERIOR...
GALE WARNING UNTIL 5 AM EDT EARLY THIS MORNING FOR LSZ243-244-
248>250-264>266.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...JLA
AVIATION...ROLFSON/SRF
MARINE...KC/JLA
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1152 PM CDT TUE MAR 12 2013
.AVIATION...
06Z TAFS FOR KOMA...KOFK...KLNK
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. THE SC DECK THAT WAS
AFFECTING THE TAF SITES EARLIER THIS EVENING HAS SHIFTED EAST
LEAVING GENERALLY CLEAR SKIES CURRENTLY. SOME MID AND HIGH LEVEL
CLOUDS WILL INCREASE TOWARD MORNING...BUT THESE ARE EXPECTED TO BE
AOA 8 K FT. WINDS WILL CONTINUE TO DIMINISH OVERNIGHT BEFORE
BECOMING SOUTH ON WED WITH SPEEDS BELOW 12 KT.
&&
.PREV DISCUSSION... /ISSUED 325 PM CDT TUE MAR 12 2013/
SHORT TERM...TONIGHT THROUGH FRIDAY.
MOSTLY CLOUDY CONDITIONS HAD DEVELOPED THROUGH THE DAY IN THE
NORTHEASTERN 2/3 OF THE FORECAST AREA...WITHIN AN AREA CYCLONIC
NORTHWESTERLY FLOW AROUND STRONG CLOSED LOW PRESSURE ACROSS THE
WESTERN GREAT LAKES. A FEW FLURRIES HAD DEVELOPED IN NORTHEAST
NEBRASKA AND NORTHWEST IOWA...BUT MORE IMPORTANTLY...WINDS GUSTING
30 TO 35 MPH HAS ALSO CREATED AREAS OF BLOWING SNOW OUT IN OPEN
RURAL AREAS. THIS WAS CREATING SOME VISIBILITY ISSUES...AS WELL
AS SOME SLICK ROADWAYS. THIS TREND WILL CONTINUE THROUGH EARLY
EVENING UNTIL THE WINDS BEGIN TO DIMINISH BY 5 TO 7 PM...ALTHOUGH
ISOLATED FLURRIES COULD STILL BE POSSIBLE IN WESTERN IOWA FOR
ANOTHER HOUR OR TWO BEYOND THAT. CLOUD TRENDS OVERNIGHT WILL BE
ALSO BE TRICKY TO FORECAST. SURFACE HIGH PRESSURE RIDGE WILL
CONTINUE MOVING IN FROM THE WEST. THIS WILL ALLOW SOME OF THE
DIURNAL CLOUDS TO DISSIPATE ON THE SOUTHWEST EDGE...HOWEVER AS
WITH PAST SEVERAL SYSTEMS...THE RAP SEEMS TO HAVE A MUCH BETTER
HANDLE ON THE LOW LEVEL CLOUDINESS...LINGERING IT MUCH LONGER THAN
OTHER MODELS WOULD SUGGEST. THIS COULD ALSO AFFECT HOURLY
TEMPERATURES...AS SKIES CLEAR IN SOME AREAS AND WINDS BECOME LIGHT
AND PERHAPS EVEN CALM IN OUR WESTERN CWA. SOME CIRRUS COULD ALSO
BEGIN TO MOVE INTO THESE SAME AREAS TOWARD DAYBREAK...AS AREAS
ALONG/EAST OF THE MISSOURI RIVER FINALLY BEGIN TO SCATTER OUT.
SOUTHEASTERLY SURFACE FLOW DEVELOPS ON WEDNESDAY AS THE MID/HIGH
CLOUDS MOVE ACROSS THE REGION. TEMPS SHOULD WARM INTO THE MID 30S
OVER THE SNOWFIELD, AND THE LOWER/MID 40S ELSEWHERE.
MEANWHILE...WARM AIR ADVECTION ALOFT WILL CONTINUE THROUGH THE
REMAINDER OF THE PERIOD. ANOTHER WEAK CLIPPER SYSTEM WILL MOVE
THROUGH THE DAKOTAS WEDNESDAY NIGHT. WHILE THIS COULD GENERATE A
SPRINKLE OR TWO IN OUR AREA AND MAYBE EVEN MEASURABLE PRECIP JUST
TO OUR NORTH/NORTHEAST...WILL MAINTAIN A DRY FORECAST AT THIS
TIME WITH PARTLY TO MOSTLY CLOUDY SKIES EXPECTED. THIS SHOULD
TRANSLATE TO DECENT WARMING ON THURSDAY...UPPER 40S OVER THE
DIMINISHING SNOW PACK...WHICH IS STILL UNDER MAV/MET GUIDANCE...
TO THE LOWER 60S OVER THE SNOW FREE AREAS. FRIDAY SHOULD BE THE
WARMEST DAY OF THE WEEK AS TEMPERATURES WARM SIGNIFICANTLY AHEAD
OF THE NEXT COLD FRONT EXPECTED FOR THE WEEKEND. TEMPS FRIDAY
SHOULD REACH THE MID 50S WHERE SOME SNOW STILL EXISTS...AND EVEN
IN THE MID TO UPPER 60S ELSEWHERE.
DEWALD
LONG TERM...FRIDAY NIGHT THROUGH TUESDAY.
THE EXTENDED PERIOD LOOKS TO BE A PERIOD OF BELOW NORMAL
TEMPERATURES WITH UNSETTLED WEATHER SATURDAY THROUGH MONDAY. WEATHER
DISTURBANCES MOVING THROUGH THE WEST AND NORTHWEST FLOW ALOFT AND
WILL BRING CHANCES OF PRECIPITATION. THE LONG RANGE MODELS ARE NOT
IN GOOD AGREEMENT IN SPECIFIC TIMING AND STRENGTH OF THE
SYSTEMS...THUS LOW CONFIDENCE IN PINNING DOWN THE THERMAL STRUCTURE
AND TIMING. A WEAK WAVE APPEARS TO MOVE THROUGH THE CENTRAL/NORTHER
PLAINS SATURDAY AND SATURDAY NIGHT...AND THE GFS LINGERS IT INTO
SUNDAY...WITH SNOW...SLEET...AND RAIN POSSIBLE. SUNDAY NIGHT INTO
MONDAY...ANOTHER STRONGER SYSTEM MOVES THROUGH. THE EC IS STRONGER
WITH THE WAVE...FARTHER NORTH WITH THE PRECIP AND MOVES IT THROUGH
FASTER WITH MORE COLD AIR AND STRONGER WINDS AVAILABLE. FOR NOW HAVE
CHANCE POPS FOR RAIN OR SNOW MENTIONED FOR SUNDAY NIGHT AND MONDAY.
ZAPOTOCNY
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
345 PM EDT WED MAR 13 2013
.SYNOPSIS...
COLD NORTHWEST WINDS FLOWING OVER THE RELATIVELY WARM WATERS OF
LAKE ONTARIO WILL BRING SNOW SHOWERS TO THE AREA TONIGHT INTO
THURSDAY. A FEW INCHES OF SNOW COULD ACCUMULATE OVER OUR NORTHERN
COUNTIES... WITH LESS TO THE SOUTH. HIGH PRESSURE WILL BRING DRY
WEATHER THURSDAY NIGHT INTO FRIDAY... THEN THE NEXT STORM SYSTEM
APPROACHING FROM THE WEST WILL BRING A CHANCE OF LIGHT SNOW OR
MIXED PRECIPITATION BY LATE FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY/...
SNOW SHOWERS ASSOCIATED WITH A POOL OF COLD AIR ALOFT WILL MOVE
ACROSS THE AREA LATE THIS AFTERNOON THROUGH MID-EVENING... WITH
SNOW SHOWERS DIMINISHING AFTER SUNSET. LATEST RAP SHORT-RANGE
FORECAST SOUNDINGS ARE STILL SHOWING SOME CAPE... GENERALLY 50 TO
150 J/KG ALONG WITH STEEP LOW-LEVEL LAPSE RATES. AS A RESULT SOME
REPORTS OF THUNDER HAVE BEEN RECEIVED FROM THE HEAVIEST SNOW
SHOWERS. WILL HAVE TO WATCH FOR SOME LOCALIZED AREAS OF SLICK
TRAVEL EARLY THIS EVENING AS ANY HEAVIER SQUALL COULD BRING A
QUICK COATING TO AN INCH OF SNOW ALONG WITH TEMPERATURES FALLING
TO NEAR OR JUST BELOW FREEZING.
SOME LAKE EFFECT SNOW BANDS WILL DEVELOP LATER THIS EVENING
THROUGH THE OVERNIGHT HOURS AS LOSS OF DIURNAL HEATING ALLOWS FOR
MORE ORGANIZATION OF THE RADAR ECHOES. LATEST GUIDANCE INDICATES
THAT 850 MB TEMPERATURES WILL FALL ALL THE WAY TO -20 C LATE
TONIGHT WHICH CERTAINLY WILL BE COLD ENOUGH FOR SOME LAKE EFFECT
GIVEN ADEQUATE SYNOPTIC-SCALE MOISTURE WHICH WILL ALSO BE IN
PLACE. FLOW WILL BE FROM AROUND 270 DEGREES LATE THIS EVENING
WHICH WILL FAVOR ANY ORGANIZED BAND TO BE NORTH OF SYRACUSE AND
THE THRUWAY. LATER TONIGHT THE FLOW SHIFTS TO BETWEEN 300 AND 310
DEGREES WHICH WILL FAVOR MULTIBANDS ACROSS A WIDE SECTION OF
CENTRAL NY. AT THIS POINT EXPECTING 2 OR 3 INCHES ACROSS MUCH OF
THE NORTHERN 1/3 OF THE FORECAST AREA BY THURSDAY MORNING.
&&
.SHORT TERM /6 AM THURSDAY THROUGH SATURDAY/...
SNOW SHOWERS WILL CONTINUE THURSDAY WITH A FLOW VECTOR FROM AROUND
300 DEGREES. ANOTHER COUPLE OF INCHES COULD FALL OVER THE NORTHERN
1/3 OF THE FORECAST AREA THROUGH LATE MORNING. DURING THE
AFTERNOON EXPECT SNOW SHOWERS TO BECOME DISORGANIZED WITH
INCREASING DIURNAL HEATING. 850 MB TEMPERATURES WILL RISE ONLY
SLIGHTLY DURING THE DAY AND ENOUGH SYNOPTIC SCALE MOISTURE WILL
REMAIN IN PLACE TO KEEP SOME SNOW SHOWERS GOING INTO THURSDAY
EVENING. TEMPERATURES WILL LIKELY REMAIN BELOW FREEZING ACROSS THE
ENTIRE AREA THROUGH THURSDAY DESPITE THE STRONG MARCH SUNSHINE.
A WEAK RIDGE OF HI PRESSURE WILL BRING A PERIOD OF DRY WEATHER
THURSDAY NIGHT INTO FRIDAY MORNING. LOW PRESSURE WILL TRACK ACROSS
SOUTHERN CANADA ON FRIDAY... DRAGGING A FRONTAL BOUNDARY SOUTH
ACROSS THE AREA DURING THE AFTERNOON. SOME MOISTURE STREAKING OUT
AHEAD OF AN APPROACHING CLIPPER SYSTEM MAY TRAIN ALONG THIS FRONT
FRIDAY AFTERNOON ALLOWING FOR SOME LIGHT SNOW OR A MIX OF LIGHT
RAIN AND SNOW TO BREAK OUT ACROSS THE AREA DURING THE DAY.
TEMPERATURES WILL RECOVER BACK ABOVE FREEZING FRIDAY AFTERNOON SO
THAT ANY SNOW THAT DOES FALL WILL LIKELY NOT ACCUMULATE MUCH.
CLIPPER SYSTEM PASSES SOUTH OF OUR AREA FRIDAY NIGHT INTO
SATURDAY. MODELS ARE IN REASONABLY GOOD AGREEMENT WITH THE TRACK
AND INTENSITY OF THIS SYSTEM... AND AS OF NOW IT LOOKS LIKE THIS
SYSTEM WILL PRODUCE A PERIOD OF ACCUMULATING SNOW FRIDAY NIGHT
INTO SATURDAY MORNING ACROSS AT LEAST A PORTION OF THE AREA.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
A HIGHLY ACTIVE PATTERN WILL DOMINATE THE NORTHERN HEMISPHERE
DURING THIS PERIOD WITH A SERIES OF FRONTAL SYSTEMS AND LOW
PRESSURE SYSTEMS PASSING THROUGH...OR NEAR THE NORTHEASTERN
AND MID-ATLANTIC STATES.
THE INITIAL WAVE IN THE SERIES IS HANDLED DIFFERENTLY BY THE GFS
AND ECMWF MODEL TRENDS. THE 13/00Z EC WOULD BRING A PERIOD OF SNOW
THROUGH PA AND SOUTHERN NY DURING SUNDAY AFTERNOON AND EVENING
WHILE THE 13/12Z GFS REMAINS SUPPRESSED FURTHER SOUTH. THE 13/12Z
CANADIAN GGEM MODEL LEANS WITH A DRIER SOLUTION FOR THIS REGION.
AT THIS TIME IT IS PRUDENT TO MENTION A CHANCE OF PRECIP EXTENDING
ACROSS NEPA AND THE SOUTHERN HALF OF CNY.
A MORE SUBSTANTIAL SYSTEM IS GENERALLY AGREED UPON WITHIN THE
MODEL SOLUTIONS TO SLIDE THROUGH THE REGION LATER MONDAY INTO
TUESDAY AS AN OCCLUDED SYSTEM. THE GFS IS A LITTLE MORE WRAPPED UP
AND FURTHER N/W. THE SYSTEM GENERALLY LOOKS MILD WITH RAIN...ALTHOUGH
A MIX WITH SNOW IS STILL HIGHLY POSSIBLE. THIS SYSTEM WILL ALSO
USHER IN AN ANOMALOUSLY SHOT OF COLD AIR TO THE REGION FOR THE
LATTER HALF OF THE WEEK.
&&
.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
18Z WED UPDATE...AN UNSTABLE ATMOSPHERE WITH A POTENT DISTURBANCE
MOVING THROUGH THE REGION HAS SPAWNED NUMEROUS BANDS OF SNOW
SHOWERS AND SQUALLS THIS AFTERNOON WHICH WILL CONTINUE INTO THE
EARLY EVENING. IN GENERAL...VFR/MVFR CIGS WILL PREVAIL BUT VSBYS
WILL BE HIGHLY VARIABLE IN AND OUT OF SQUALLS. MOST SNOW SHOWERS
WILL PRODUCE IFR VSBYS...BUT THE HEAVIEST SQUALLS COULD PRODUCE
NEAR WHITEOUT CONDITIONS FOR A SHORT AMOUNT OF TIME OVER THE
TERMINAL.
BEYOND ABOUT 00Z...SNOW SHOWERS WILL BECOME MORE SPORADIC AND
BECOME FOCUSED ALONG THE DOWNWIND TRAJECTORY OF LAKE ONTARIO
MAINLY AFFECTING KSYR-KRME WITH THE MOST RESTRICTIONS. ELSEWHERE...
DEEPENING COLD AIR WILL KEEP CIGS IN THE MVFR CATEGORY THROUGH
THURSDAY MORNING WITH SOME IMPROVEMENT TO VFR.
WINDS SW 10-15 KTS INTO THIS EVENING...BECOMING W-NW AND
INCREASING 15-25 KTS AND GUSTY LATER TONIGHT AND THURSDAY.
.OUTLOOK...
FRIDAY...MAINLY VFR BY AFTERNOON.
FRIDAY NIGHT/SATURDAY EVE...RESTRICTIONS POSSIBLE IN LIGHT SNOW.
SUNDAY...VFR.
MONDAY...BECOMING MVFR IN A RAIN/SNOW MIX.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MSE
NEAR TERM...MSE
SHORT TERM...MSE
LONG TERM...JAB
AVIATION...JAB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1000 PM EDT THU MAR 14 2013
.SYNOPSIS...
HIGH PRESSURE WILL HOLD OVER THE GULF COAST AND SOUTHEAST STATES
THROUGH EARLY FRIDAY. A WARM FRONT WILL MOVE NORTHEASTWARD THROUGH
THE CAROLINAS ON FRIDAY... THEN A BACKDOOR COLD FRONT WILL DROP INTO
THE AREA FROM THE NORTH BY LATE SATURDAY... AND REMAIN ACROSS NORTH
CAROLINA THROUGH SUNDAY.
&&
.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 730 PM THURSDAY...
VFR CONDITIONS CONTINUE ACROSS CENTRAL NC UNDER NORTHWEST FLOW ALOFT
AND PERIODS OF MID AND HIGH CLOUDS. NORTHWESTERLY WINDS HAVE
WEAKENED WITH SUNSET...BUT WILL REMAIN AROUND 5KT OVERNIGHT. AN
UPPER LEVEL DISTURBANCE CURRENTLY OVER IL/KY WILL DIVE SOUTHEAST
ACROSS SC/GA BETWEEN 03Z AND 09Z. WHILE THERE ARE SOME LIGHT
SHOWERS UPSTREAM OF THE MOUNTAINS...THERE IS HIGH CONFIDENCE THAT
CONDITIONS WILL REMAIN DRY EAST OF THE MOUNTAINS ACROSS CENTRAL NC.
THUS...VFR CONDITIONS ARE EXPECTED TO PREVAIL.
AHEAD OF A COLD FRONT MOVING THROUGH THE MIDWEST... WINDS WILL SHIFT
TO SOUTHWESTERLY DURING THE DAY ON FRIDAY...STRENGTHENING TO AROUND
12KT ONCE AGAIN BY MIDDAY WITH PERIODIC GUSTS TO AROUND 20KT.
OUTLOOK...
VFR CONDITIONS WILL CONTINUE THROUGH SATURDAY. SOME LOW-LEVEL WIND
SHEAR OR TURBULENCE IS POSSIBLE FRIDAY NIGHT AS WINDS JUST ABOVE THE
SURFACE INCREASE ABOVE 30KT WHILE SURFACE WINDS REMAIN WEAK. A COLD
FRONT WILL SLIP SOUTH INTO THE AREA BY SUNDAY MORNING...WITH PERIODS
OF RAIN AND MVFR/IFR CONDITIONS THROUGH MONDAY. THE FRONT IS
EXPECTED TO LIFT NORTH OF THE AREA LATE MONDAY...WITH ANOTHER COLD
FRONT TO SWEEP ACROSS THE AREA TUESDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...BSD/HARTFIELD
SHORT TERM..WSS
LONG TERM...WSS
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
730 PM EDT THU MAR 14 2013
.SYNOPSIS...
HIGH PRESSURE WILL HOLD OVER THE GULF COAST AND SOUTHEAST STATES
THROUGH EARLY FRIDAY. A WARM FRONT WILL MOVE NORTHEASTWARD THROUGH
THE CAROLINAS ON FRIDAY... THEN A BACKDOOR COLD FRONT WILL DROP INTO
THE AREA FROM THE NORTH BY LATE SATURDAY... AND REMAIN ACROSS NORTH
CAROLINA THROUGH SUNDAY.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 305 PM THURSDAY...
THROUGH TONIGHT: WE`RE ALREADY SEEING SOME OROGRAPHIC CIRRUS OVER
THE FAR WRN CWA... AND THE MID/HIGH CLOUDS ASSOCIATED WITH THE MID
LEVEL SHORTWAVE DIVING QUICKLY TO THE SOUTHEAST TOWARD GA/SC IS ON
TRACK TO OVERSPREAD THE CAROLINAS WITHIN THE NEXT HOUR OR TWO.
EXPECT SKIES TO BECOME PARTLY TO MOSTLY CLOUDY... WITH THE THICKEST
CLOUDS IN THE SOUTHWEST CWA. CLOUD COVER IS EXPECTED TO DECREASE
TOWARD MORNING AS THE WAVE PUSHES OFF THE GA/SC COAST. WITH THE
CLOUDS EXPECTED TO PROVIDE ENOUGH DOWNWARD IR TO TEMPER NIGHTTIME
COOLING... HAVE ADJUSTED LOWS UP SLIGHTLY... TO 28-34.
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 730 PM THURSDAY...
VFR CONDITIONS CONTINUE ACROSS CENTRAL NC UNDER NORTHWEST FLOW ALOFT
AND PERIODS OF MID AND HIGH CLOUDS. NORTHWESTERLY WINDS HAVE
WEAKENED WITH SUNSET...BUT WILL REMAIN AROUND 5KT OVERNIGHT. AN
UPPER LEVEL DISTURBANCE CURRENTLY OVER IL/KY WILL DIVE SOUTHEAST
ACROSS SC/GA BETWEEN 03Z AND 09Z. WHILE THERE ARE SOME LIGHT
SHOWERS UPSTREAM OF THE MOUNTAINS...THERE IS HIGH CONFIDENCE THAT
CONDITIONS WILL REMAIN DRY EAST OF THE MOUNTAINS ACROSS CENTRAL NC.
THUS...VFR CONDITIONS ARE EXPECTED TO PREVAIL.
AHEAD OF A COLD FRONT MOVING THROUGH THE MIDWEST... WINDS WILL SHIFT
TO SOUTHWESTERLY DURING THE DAY ON FRIDAY...STRENGTHENING TO AROUND
12KT ONCE AGAIN BY MIDDAY WITH PERIODIC GUSTS TO AROUND 20KT.
OUTLOOK...
VFR CONDITIONS WILL CONTINUE THROUGH SATURDAY. SOME LOW-LEVEL WIND
SHEAR OR TURBULENCE IS POSSIBLE FRIDAY NIGHT AS WINDS JUST ABOVE THE
SURFACE INCREASE ABOVE 30KT WHILE SURFACE WINDS REMAIN WEAK. A COLD
FRONT WILL SLIP SOUTH INTO THE AREA BY SUNDAY MORNING...WITH PERIODS
OF RAIN AND MVFR/IFR CONDITIONS THROUGH MONDAY. THE FRONT IS
EXPECTED TO LIFT NORTH OF THE AREA LATE MONDAY...WITH ANOTHER COLD
FRONT TO SWEEP ACROSS THE AREA TUESDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM..WSS
LONG TERM...WSS
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
253 AM EDT WED MAR 13 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD TOWARD THE REGION FROM THE WEST TODAY
THROUGH THURSDAY. A CLIPPER LOW WILL TRACK RAPIDLY SOUTHEAST INTO
THE MID ATLANTIC AND CAROLINAS THURSDAY NIGHT.
&&
.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
AS OF 930 PM TUESDAY...
THROUGH TONIGHT: SKIES HAVE CLEARED ACROSS ALL OF CENTRAL NC AS THE
COLD FRONT WHICH BROUGHT TODAY`S RAIN HAS SHIFTED TO COASTAL
SECTIONS AND IS POISED TO MOVE OFFSHORE... PROPELLED BY COOL HIGH
PRESSURE EXTENDING FROM CENTRAL CANADA DOWN THROUGH THE PLAINS AND
LOWER MISS VALLEY. THE DIFFERENCE BETWEEN THE 00Z SOUNDINGS AT MHX
(SOME LINGERING MOISTURE BELOW 850 MB) AND GSO (VERY DRY AIR THROUGH
THE COLUMN) TELLS THE STORY... AS DOES THE WATER VAPOR IMAGERY
SHOWING WELL THE SLUG OF DRY AIR SWEEPING TO THE NE THROUGH CENTRAL
NC. UPPER LEVEL TRAJECTORIES DO SUGGEST HOWEVER THAT THE HIGH CLOUDS
NOW STREAMING ACROSS ARK AND THE MEMPHIS AREA WILL SWEEP ACROSS NC
TOWARD MIDNIGHT AND DURING THE OVERNIGHT HOURS... ALSO INDICATED BY
THE RAP SOUNDINGS. WILL INCLUDE A THIN VEIL OF CLOUDS OVERNIGHT...
BUT OTHERWISE SKIES SHOULD BE CLEAR. AS THE SURFACE RIDGE BUILDS IN
OVERNIGHT WITH NORTHEASTERLY SURFACE WINDS AND COLD AIR ADVECTION...
THICKNESSES ARE EXPECTED TO PLUMMET... FROM MUCH ABOVE NORMAL
READINGS TODAY TO JUST BELOW NORMAL READINGS BY MORNING... ALTHOUGH
THE MORE SIGNIFICANT DROP COMES WEDNESDAY INTO WEDNESDAY NIGHT WITH
THE ARRIVAL OF THE POLAR FRONT. BOTH TEMPS AND DEW POINTS ARE
TRENDING VERY CLOSE TO THE FORECAST PACE...AND LOWS OF 34-42 STILL
LOOK REASONABLE. -GIH
WEDNESDAY AND WEDNESDAY NIGHT: POTENT SHORTWAVE ENERGY UPSTREAM OVER
MINNESOTA WILL DIG SOUTHEAST INTO THE TN VALLEY TONIGHT AND THEN
THROUGH THE CAROLINAS AND VIRGINIA ON WEDNESDAY. AS THE POTENT
VORTMAX SWINGS THROUGH THE AREA...STRONG DCVA AIDED BY COOLING ALOFT
WILL RESULT IN STRONG MID AND UPPER LEVEL ASCENT. AIRMASS WILL BE
TOO DRY TO SUPPORT OTHER THAN A PERIOD OF A PERIOD OF BROKEN TO
OVERCAST MID CLOUDS WEDNESDAY AFTERNOON. AN ATYPICALLY COLD AIRMASS
ALOFT (H85 TEMPS 1-2 STD DEVIATIONS BELOW NORMAL)IN THE PRESENCE OF
DEEP VERTICAL MIXING WILL RESULT IN BELOW NORMAL TEMPERATURES WITH
BREEZY NWLY WIND GUSTS BETWEEN 20 TO 25KTS. BOTH THE DRY-ADIABATIC
AND LOW-LEVEL THICKNESS TEMPERATURES SCHEME SUGGEST AFTERNOON HIGHS
A GOOD 5 TO 8 DEGREES BELOW STATISTICAL MOS GUIDANCE.
HOWEVER...CONSIDERING THE EVER INCREASING SUN ANGLE THIS TIME OF
YEAR...AM CONCERNED CURRENT FORECAST MAY BE A TOUCH TOO COOL...BUT
THE EXPECTED PERIOD OF BROKEN MID-LEVEL CLOUD COVER SHOULD HELP.
HIGHS NEAR 50 NW TO MID/UPPER 50S SOUTHEAST.
A SECONDARY ROUND OF LOW-LEVEL COLD ADVECTION WILL OCCUR WEDNESDAY
EVENING/NIGHT IN ASSOCIATION WITH RENEWED LOW-LEVEL NWLY FLOW
IN THE WAKE OF THE EXITING UPPER LEVEL TROUGH. MINS FOR THE SECOND
CONSECUTIVE NIGHT WILL BE DRIVEN BY CAA. LOWS WED NIGHT IN THE UPPER
20S TO LOWER 30S. -CBL
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
AS OF 320 PM TUESDAY...
A STRONG UPPER LEVEL TROUGH WILL STILL BE IN PLACE ALONG THE EASTERN
US ON THURSDAY. THIS...ALONG WITH CONTINUED COLD AIR ADVECTION
(NORTHWESTERLY WINDS OF 10-15 MPH WILL LEAD TO ANOTHER DAY OF BELOW
NORMAL TEMPS. HIGHS ARE ONLY EXPECTED TO BE IN THE LOW 50S (POSSIBLY
STRUGGLING TO EVEN REACH 50 DEGREES IN SOME LOCATIONS). THE UPPER
LEVEL TROUGH AXIS WILL MOVE OFFSHORE THURSDAY NIGHT...BUT A
DISTURBANCE WITHIN THE NORTHWEST FLOW ALOFT WILL MOVE SOUTHEASTWARD
ACROSS THE REGION THURSDAY NIGHT INTO FRIDAY MORNING. IT STILL
APPEARS THE MAIN IMPACT FROM THIS FEATURE WILL BE AN INCREASE IN MID
LEVEL CLOUD COVER AS THE BOUNDARY LAYER IS PROGGED TO BE RATHER DRY.
HOWEVER...CANNOT COMPLETELY SOME SPRINKLES OR A LIGHT SHOWER...
ESPECIALLY ACROSS THE WESTERN PORTIONS OF THE FORECAST AREA. DESPITE
CLOUD COVER...OVERNIGHT LOWS WILL GENERALLY BE WITHIN A DEGREE OR
TWO OF FREEZING. CLOUDS WILL DECREASE THROUGHOUT THE DAY ON FRIDAY
AS SUBSIDENCE INCREASES ON THE BACKSIDE OF THE DEPARTING SHORTWAVE.
AS HEIGHTS INCREASE SOME...TEMPS WILL BEGIN TO MODERATE...WITH
HIGHS IN THE MID/UPPER 50S AND OVERNIGHT LOWS IN THE MID/UPPER 30S
EXPECTED.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 250 AM WEDNESDAY...
FRIDAY NIGHT THROUGH SUNDAY NIGHT:
THE H85 RIDGE OVER THE GULF SHOULD DEAMPLIFY AS A LOW PRESSURE
SYSTEM MOVES ACROSS THE GREAT LAKES REGION FRIDAY NIGHT INTO
SATURDAY. A GOOD DEAL OF UNCERTAINTY STILL REMAINS BETWEEN THE 00Z
GFS AND 12Z ECMWF WITH REGARD TO STRENGTH AND TIMING OF THE SYSTEM
AND ASSOCIATED BACKDOOR COLD FRONT...WHICH WILL IN TURN HAVE AN
IMPACT ON TEMPS AND PRECIP THROUGH THE PERIOD. THE ECMWF TENDS TO
AMPLIFY THE TROUGH A BIT MORE THAN THE 00Z GFS... HOWEVER BOTH
MODELS AGREE ON A WEST TO EAST ORIENTED FRONTAL BOUNDARY IN THE
VICINITY OF CENTRAL NC SATURDAY THROUGH SUNDAY NIGHT. THE GFS
PLACES THE FRONT IN THE VICINITY OF THE NC/SC BORDER AND THE ECMWF
PLACES IT FARTHER NORTH...NEAR THE NC/VA BORDER. THIS DIFFERENCE HAS
SIGNIFICANT IMPACTS ON PRECIP LOCATION AND TEMPS FOR THE PERIOD. IN
GENERAL...EXPECT HIGH TEMPS SLIGHTLY ABOVE NORMAL SATURDAY AND...
BASED ON THE GFS FRONTAL POSITIONING...SLIGHTLY BELOW NORMAL ON
SUNDAY. OVERNIGHT LOWS GENERALLY IN THE LOW TO MID 40S. GFS FORECAST
SOUNDINGS INDICATE MOISTURE INCREASING FROM THE TOP DOWN STARTING
SATURDAY...SATURATING THROUGHOUT THE COLUMN FROM NORTH TO SOUTH BY
SUNDAY NIGHT. GIVEN THE CURRENT MODEL DIFFERENCES AND DEGREE OF
UNCERTAINTY...WILL CONTINUE TO LEAN TOWARD THE MORE CONSISTENT GFS
SOLUTION...WITH SLIGHT CHANCE OF RAIN ACROSS THE NORTH BEGINNING
SATURDAY AFTERNOON...EXTENDING ACROSS THE ENTIRE AREA BY SUNDAY.
MONDAY THROUGH TUESDAY:
THE MODELS AGREE THAT A STRONG LOW PRESSURE SYSTEM WILL DEVELOP IN
THE LEE OF THE ROCKIES SUNDAY NIGHT AND DEEPEN AS IT MOVES EAST AND
NORTHEAST THROUGH THE GREAT LAKES TOWARD THE END OF THE PERIOD. AT
THE SURFACE...THE LOW AND ASSOCIATED COLD FRONT WILL PUSH THE HIGH
OUT OF THE NE AND BRING THE CHANCE FOR ANOTHER ROUND OF PRECIP
THROUGH THE AREA. THERE IS SOME INDICATION IN THE MODELS OF A PERIOD
OF LIGHT PRECIP ACROSS THE WEST AHEAD OF THE MAIN SYSTEM...LIKELY
THE PRODUCT OF SOME ISENTROPIC LIFT AS THE ENE RETURN FLOW ADVECTS
LOW LEVEL MOISTURE INTO THE AREA. MODELS ARE TRENDING DRIER WITH THE
FROPA TUESDAY...AS WESTERLY FLOW OFF THE APPALACHIANS INDUCES
SUBSIDENCE. WITH SOME UNCERTAINTY WITH REGARD TO LOCATION OF THE
PARENT LOW AND TIMING OF THE FROPA...WILL CARRY SLIGHT CHANCE OF
RAIN INTO TUESDAY...WITH GFS FORECAST SOUNDINGS INDICATING DRYING
BEHIND IT. HIGH TEMPS MONDAY AND TUESDAY IN THE UPPER 50S NORTH TO
MID 60S SOUTH. LOW TEMPS MONDAY NIGHT IN THE MID TO UPPER 40S...
DECREASING TUESDAY NIGHT BEHIND THE FRONT...MID 30S NORTHWEST TO LOW
40S SOUTHEAST.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 115 AM WEDNESDAY...
24-HR TAF PERIOD:
VFR CONDITIONS WILL RULE THROUGH THE TAF PERIOD IN ASSOCIATION WITH
A DRY AIRMASS IN PLACE OVER THE REGION. NORTHWEST WINDS AT 5-10 KT
WILL PREVAIL THROUGH 12Z THIS MORNING. WINDS WILL BACK TO A MORE
WESTERLY DIRECTION AND INCREASE TO ~15 KT SUSTAINED WITH GUSTS UP TO
~25 KT BY 15-18Z. WINDS WILL VEER TO THE NORTHWEST AT 10-15 KT WITH
GUSTS UP TO 20 KT BY 00Z THIS EVENING...WITH GUSTS BECOMING MORE
SPORADIC IN NATURE OVERNIGHT.
LOOKING AHEAD:
VFR CONDITIONS AND A NORTHWEST BREEZE WILL PERSIST ON THURSDAY. A
FAST MOVING CLIPPER LOW WILL TRACK SOUTHEAST THROUGH THE CAROLINAS
THURSDAY NIGHT AND EARLY FRIDAY MORNING...HOWEVER...AT THIS TIME
ANTICIPATE THAT CEILINGS WILL REMAIN AT OR ABOVE 4-5 KFT AGL. VFR
CONDITIONS WILL PERSIST THROUGH FRIDAY NIGHT...WITH THE NEXT CHANCE
OF SUB-VFR CONDITIONS ON SAT/SUN IN ASSOCIATION WITH A COLD FRONT
EXPECTED TO MOVE INTO THE REGION FROM THE NORTH. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...HARTFIELD/CBL
SHORT TERM..KRR
LONG TERM...KC
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
118 AM EDT WED MAR 13 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD TOWARD THE REGION FROM THE WEST TODAY
THROUGH THURSDAY. A CLIPPER LOW WILL TRACK RAPIDLY SOUTHEAST INTO
THE MID ATLANTIC AND CAROLINAS THURSDAY NIGHT.
&&
.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
AS OF 930 PM TUESDAY...
THROUGH TONIGHT: SKIES HAVE CLEARED ACROSS ALL OF CENTRAL NC AS THE
COLD FRONT WHICH BROUGHT TODAY`S RAIN HAS SHIFTED TO COASTAL
SECTIONS AND IS POISED TO MOVE OFFSHORE... PROPELLED BY COOL HIGH
PRESSURE EXTENDING FROM CENTRAL CANADA DOWN THROUGH THE PLAINS AND
LOWER MISS VALLEY. THE DIFFERENCE BETWEEN THE 00Z SOUNDINGS AT MHX
(SOME LINGERING MOISTURE BELOW 850 MB) AND GSO (VERY DRY AIR THROUGH
THE COLUMN) TELLS THE STORY... AS DOES THE WATER VAPOR IMAGERY
SHOWING WELL THE SLUG OF DRY AIR SWEEPING TO THE NE THROUGH CENTRAL
NC. UPPER LEVEL TRAJECTORIES DO SUGGEST HOWEVER THAT THE HIGH CLOUDS
NOW STREAMING ACROSS ARK AND THE MEMPHIS AREA WILL SWEEP ACROSS NC
TOWARD MIDNIGHT AND DURING THE OVERNIGHT HOURS... ALSO INDICATED BY
THE RAP SOUNDINGS. WILL INCLUDE A THIN VEIL OF CLOUDS OVERNIGHT...
BUT OTHERWISE SKIES SHOULD BE CLEAR. AS THE SURFACE RIDGE BUILDS IN
OVERNIGHT WITH NORTHEASTERLY SURFACE WINDS AND COLD AIR ADVECTION...
THICKNESSES ARE EXPECTED TO PLUMMET... FROM MUCH ABOVE NORMAL
READINGS TODAY TO JUST BELOW NORMAL READINGS BY MORNING... ALTHOUGH
THE MORE SIGNIFICANT DROP COMES WEDNESDAY INTO WEDNESDAY NIGHT WITH
THE ARRIVAL OF THE POLAR FRONT. BOTH TEMPS AND DEW POINTS ARE
TRENDING VERY CLOSE TO THE FORECAST PACE... AND LOWS OF 34-42 STILL
LOOK REASONABLE. -GIH
WEDNESDAY AND WEDNESDAY NIGHT: POTENT SHORTWAVE ENERGY UPSTREAM OVER
MINNESOTA WILL DIG SOUTHEAST INTO THE TN VALLEY TONIGHT AND THEN
THROUGH THE CAROLINAS AND VIRGINIA ON WEDNESDAY. AS THE POTENT
VORTMAX SWINGS THROUGH THE AREA...STRONG DCVA AIDED BY COOLING ALOFT
WILL RESULT IN STRONG MID AND UPPER LEVEL ASCENT. AIRMASS WILL BE
TOO DRY TO SUPPORT OTHER THAN A PERIOD OF A PERIOD OF BROKEN TO
OVERCAST MID CLOUDS WEDNESDAY AFTERNOON. AN ATYPICALLY COLD AIRMASS
ALOFT (H85 TEMPS 1-2 STD DEVIATIONS BELOW NORMAL)IN THE PRESENCE OF
DEEP VERTICAL MIXING WILL RESULT IN BELOW NORMAL TEMPERATURES WITH
BREEZY NWLY WIND GUSTS BETWEEN 20 TO 25KTS. BOTH THE DRY-ADIABATIC
AND LOW-LEVEL THICKNESS TEMPERATURES SCHEME SUGGEST AFTERNOON HIGHS
A GOOD 5 TO 8 DEGREES BELOW STATISTICAL MOS GUIDANCE.
HOWEVER...CONSIDERING THE EVER INCREASING SUN ANGLE THIS TIME OF
YEAR...AM CONCERNED CURRENT FORECAST MAY BE A TOUCH TOO COOL...BUT
THE EXPECTED PERIOD OF BROKEN MID-LEVEL CLOUD COVER SHOULD HELP.
HIGHS NEAR 50 NW TO MID/UPPER 50S SOUTHEAST.
A SECONDARY ROUND OF LOW-LEVEL COLD ADVECTION WILL OCCUR WEDNESDAY
EVENING/NIGHT IN ASSOCIATION WITH RENEWED LOW-LEVEL NWLY FLOW
IN THE WAKE OF THE EXITING UPPER LEVEL TROUGH. MINS FOR THE SECOND
CONSECUTIVE NIGHT WILL BE DRIVEN BY CAA. LOWS WED NIGHT IN THE UPPER
20S TO LOWER 30S. -CBL
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
AS OF 320 PM TUESDAY...
A STRONG UPPER LEVEL TROUGH WILL STILL BE IN PLACE ALONG THE EASTERN
US ON THURSDAY. THIS...ALONG WITH CONTINUED COLD AIR ADVECTION
(NORTHWESTERLY WINDS OF 10-15 MPH WILL LEAD TO ANOTHER DAY OF BELOW
NORMAL TEMPS. HIGHS ARE ONLY EXPECTED TO BE IN THE LOW 50S (POSSIBLY
STRUGGLING TO EVEN REACH 50 DEGREES IN SOME LOCATIONS). THE UPPER
LEVEL TROUGH AXIS WILL MOVE OFFSHORE THURSDAY NIGHT...BUT A
DISTURBANCE WITHIN THE NORTHWEST FLOW ALOFT WILL MOVE SOUTHEASTWARD
ACROSS THE REGION THURSDAY NIGHT INTO FRIDAY MORNING. IT STILL
APPEARS THE MAIN IMPACT FROM THIS FEATURE WILL BE AN INCREASE IN MID
LEVEL CLOUD COVER AS THE BOUNDARY LAYER IS PROGGED TO BE RATHER DRY.
HOWEVER...CANNOT COMPLETELY SOME SPRINKLES OR A LIGHT SHOWER...
ESPECIALLY ACROSS THE WESTERN PORTIONS OF THE FORECAST AREA. DESPITE
CLOUD COVER...OVERNIGHT LOWS WILL GENERALLY BE WITHIN A DEGREE OR
TWO OF FREEZING. CLOUDS WILL DECREASE THROUGHOUT THE DAY ON FRIDAY
AS SUBSIDENCE INCREASES ON THE BACKSIDE OF THE DEPARTING SHORTWAVE.
AS HEIGHTS INCREASE SOME...TEMPS WILL BEGIN TO MODERATE...WITH
HIGHS IN THE MID/UPPER 50S AND OVERNIGHT LOWS IN THE MID/UPPER 30S
EXPECTED.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 320 PM TUESDAY...
UNCERTAINTY REMAINS HIGH DURING THE LONG TERM PERIOD. OVERALL...THE
FLOW ALOFT IS PROGGED TO DEAMPLIFY AND TEMPS SHOULD GRADUALLY MODIFY
THROUGH THE WEEKEND. MODELS ARE STILL INDICATING A BACKDOOR FRONT
MOVING INTO THE AREA ON SATURDAY...BUT THERE IS CONSIDERABLE
DISAGREEMENT ON HOW TO HANDLE THIS FRONT. THE LAST COUPLE OF RUNS OF
THE GFS PUSH THE FRONT SOUTH OF THE AREA SATURDAY NIGHT...WHILE THE
ECMWF STALLS THE FRONT SOMEWHERE NEAR THE FORECAST AREA. THIS
CREATES A LOT OF DISAGREEMENT WITH RESPECT TO BOTH PRECIP CHANCES
AND TEMPS. THEN MODELS SHOW A WAVE OF LOW PRESSURE DEVELOPING ON THE
FRONT SUNDAY INTO MONDAY AND TRACKING EAST...ALTHOUGH WHERE EXACTLY
THIS FRONT WILL BE (AND ASSOCIATED LOW TRACK) IS STILL IN QUESTION.
MODELS ARE THEN IN GENERAL AGREEMENT WITH A MORE AMPLIFIED TROUGH
ALOFT MOVING INTO THE MIDWEST ON TUESDAY...WITH AN ASSOCIATED
SURFACE FRONT PROGGED TO CROSS THE REGION TUESDAY/TUESDAY NIGHT.
GIVEN ALL THE UNCERTAINTY WILL NOT CHANGE THE FORECAST TOO
MUCH...WITH SLIGHT CHANCE POPS OVER THE WEEKEND...BEFORE SLIGHTLY
HIGHER POPS FOR EARLY NEXT WEEK. TEMPS ARE EXPECTED TO BE ABOVE
NORMAL ON SATURDAY (AHEAD OF THE BACKDOOR FRONT)...WITH NEAR NORMAL
TEMPS FOR THE REMAINDER OF THE PERIOD (ALTHOUGH IT WILL BE HIGHLY
DEPENDENT ON FRONTAL POSITION).
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 115 AM WEDNESDAY...
24-HR TAF PERIOD:
VFR CONDITIONS WILL RULE THROUGH THE TAF PERIOD IN ASSOCIATION WITH
A DRY AIRMASS IN PLACE OVER THE REGION. NORTHWEST WINDS AT 5-10 KT
WILL PREVAIL THROUGH 12Z THIS MORNING. WINDS WILL BACK TO A MORE
WESTERLY DIRECTION AND INCREASE TO ~15 KT SUSTAINED WITH GUSTS UP TO
~25 KT BY 15-18Z. WINDS WILL VEER TO THE NORTHWEST AT 10-15 KT WITH
GUSTS UP TO 20 KT BY 00Z THIS EVENING...WITH GUSTS BECOMING MORE
SPORADIC IN NATURE OVERNIGHT.
LOOKING AHEAD:
VFR CONDITIONS AND A NORTHWEST BREEZE WILL PERSIST ON THURSDAY. A
FAST MOVING CLIPPER LOW WILL TRACK SOUTHEAST THROUGH THE CAROLINAS
THURSDAY NIGHT AND EARLY FRIDAY MORNING...HOWEVER...AT THIS TIME
ANTICIPATE THAT CEILINGS WILL REMAIN AT OR ABOVE 4-5 KFT AGL. VFR
CONDITIONS WILL PERSIST THROUGH FRIDAY NIGHT...WITH THE NEXT CHANCE
OF SUB-VFR CONDITIONS ON SAT/SUN IN ASSOCIATION WITH A COLD FRONT
EXPECTED TO MOVE INTO THE REGION FROM THE NORTH. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...HARTFIELD/CBL
SHORT TERM..KRR
LONG TERM...KRR
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1158 AM CDT WED MAR 13 2013
.DISCUSSION...LATEST SURFACE ANALYSIS SHOWS SURFACE LOW PRESSURE
IN SOUTHEAST ALBERTA WITH MAX PRESSURE FALLS IN EASTERN SASKATCHEWAN
SOUTH INTO NORTH CENTRAL NORTH DAKOTA. THE LOW WILL TRACK TOWARD
THE SOUTHEAST THROUGH THIS EVENING...TO NEAR BISMARCK BY 06Z THURSDAY.
STRONG WARM AIR ADVECTION WITH THIS WAVE AS H85 TEMPS PER RAP MODEL
ADVERTISING +8 TO +10C SOUTHEASTERN ALBERTA. THIS WILL SHIFT INTO
WESTERN AND PORTIONS OF CENTRAL NORTH DAKOTA FOLLOWING THE PASSAGE
OF THE SURFACE LOW LATE TONIGHT INTO THURSDAY. IN ADVANCE OF THE
LOW THIS AFTERNOON...WILL CONTINUE TO MENTION AN ISOLATED MIX IN
THE NORTH AS VERTICAL MOTION INCREASES IN ASSOCIATION WITH THE
LEFT EXIT REGION OF A 120KT JET. THE LIGHT PRECIPITATION THREAT
WILL EXPAND INTO THE JAMES RIVER VALLEY TONIGHT PER LATEST RAP/NAM/GFS.
PRECIPITATION AMOUNTS ARE VERY LIGHT. ADJUSTED THE HIGHS IN THE
SOUTHWEST UP A FEW DEGREES BASED ON LATEST OBSERVATIONS AND STILL
PLENTY OF TIME WITH AMPLE SUNSHINE THIS AFTERNOON TO RISE.
LATEST 12Z MODEL SUITE STILL ON TRACK FOR SNOW IN THE NORTH THURSDAY
NIGHT AND FRIDAY. THE POTENTIAL FOR FREEZING RAIN CONTINUES TO
SHRINK. THUS THE CURRENT THINKING RIGHT IS DOING A SPECIAL WEATHER
STATEMENT MOST LIKELY ALONG AND NORTH OF HIGHWAY 2 FOR THURSDAY
NIGHT AND FRIDAY WITH POSSIBLE ADVISORY LEVEL SNOW AMOUNTS. WILL
CONTINUE TO LOOK AT THINGS...BUT THAT IS THE DIRECTION WE ARE
LEANING TOWARDS AT THIS TIME.
&&
.AVIATION...FOR THE UPCOMING 18 UTC TAF CYCLE...VFR CONDITIONS WILL
PREVAIL ACROSS WESTERN AND CENTRAL NORTH DAKOTA FOR THE AFTERNOON
AND INTO THE EARLY EVENING AS HIGH PRESSURE ACROSS EASTERN NORTH
DAKOTA SHIFTS SLOWLY SOUTHEAST. HOWEVER...MVFR STRATUS CURRENTLY
ACROSS ALBERTA AS OF 17 UTC WILL CONTINUE TO MOVE SOUTHEAST SPREADING
ACROSS WESTERN AND CENTRAL NORTH DAKOTA LATE THIS EVENING AND
TONIGHT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...KS
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
404 AM CDT WED MAR 13 2013
.SHORT TERM...TODAY THROUGH THURSDAY...
THE MAIN HIGHLIGHT OF THE SHORT TERM PERIOD IS PRECIPITATION
CHANCES THIS MORNING AND AGAIN TONIGHT.
CURRENTLY...LATEST RADAR REFLECTIVITIES AT 0830Z SHOW SCATTERED
SNOW SHOWERS OVER EASTERN MONTANA THROUGH NORTHWEST SOUTH DAKOTA
ASSOCIATED WITH AN EASTWARD MOVING WARM FRONT. ACROSS THE
WEST...SURFACE OBSERVATIONS OVER THE LAST COUPLE OF HOURS HAVE YET
TO REFLECT ANY SNOW REACHING THE SURFACE. THE 00Z SUITE OF
DETERMINISTIC MODELS ARE IN DISAGREEMENT REGARDING PRECIP AND QPF.
THE 00Z ECWMF/GFS PAINT LIGHT QPF OVER THE WEST OVER THE NEXT FEW
HOURS...WHILE THE NAM/GEM KEEP THE WEST DRY. THE 07Z RAP HAS THE
AREA OF SNOW SHOWERS CONTINUING TO MOVE EAST...BUT THEN STALL AND
DIMINISH ACROSS THE WEST LATER THIS MORNING. FOR NEAR TERM
POPS...HAVE USED A BLEND OF THE GFS/ECWMF/RAP. SNOW ACCUMULATIONS
ARE EXPECTED TO BE UNDER A HALF INCH.
THE AFOREMENTIONED WARM FRONT WILL CONTINUE TO PUSH EAST AND OVER
NORTH DAKOTA TODAY. WITH WARM AIR ADVECTION TAKING
PLACE OVER THE AREA...THERE WILL BE SHARP TEMPERATURE GRADIENT
DEVELOPING. WHERE RECENT SNOW HAS FALLEN AND IS STILL IN
PLACE...TEMPERATURES WILL REMAIN SEASONABLE AND IN THE UPPER 20S
AND LOWER 30S. THE GREATEST WARM UP WILL BE FOR THE SNOWLESS
SOUTHWEST...WHERE TEMPERATURES WILL WARM INTO THE MID TO UPPER 50S.
FOR TONIGHT...A WEAK UPPER LEVEL IMPULSE WILL MOVE ACROSS THE
AREA...BRINGING A PERIOD OF LIGHT PRECIPITATION THROUGH FRIDAY MORNING.
THERE IS DISAGREEMENT BETWEEN THE 00Z MODEL SOLUTIONS...WITH THE
NAM/GEM KEEPING PRECIP FURTHER EAST...THE ECWMF BEING MORE
PROGRESSIVE...AND THE GFS BRINGING LIGHT QPF TO THE AREA. HAVE
UTILIZED A BLEND OF THE 00Z GFS/ECWMF SOLUTIONS. PRECIPITATION
WILL BE IN THE FORM LIGHT RAIN FOR LOCATIONS ALONG THE
MISSOURI...AS THE THERMAL PROFILE WILL BE ABOVE FREEZING...AND AS
LIGHT WINTRY MIX ACROSS THE NORTH. ANY ACCUMULATING SNOW WILL BE
CONFINED TO THE TURTLE MOUNTAINS AND FAR EAST...WHERE OVERNIGHT
TEMPERATURES WILL COOL INTO THE UPPER 20S.
FOR THURSDAY...A DRY AND MILD DAY IS EXPECTED. THURSDAY AFTERNOON
HIGHS WILL BE 10 TO 15 DEGREES WARMER THAN NORMAL FOR THE
SOUTHWEST AND SOUTH CENTRAL...WHERE TEMPERATURES WILL CLIMB INTO
THE MID TO UPPER 50S. FOR THE FAR SOUTHWEST...LOWER 60S ARE A
POSSIBILITY. ELSEWHERE...TEMPERATURES WILL BE IN THE 30S AND 40S.
.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...
FRONTOGENESIS ALONG A BAROCLINIC ZONE OVER NORTHWESTERN NORTH DAKOTA
IS PROGGED TO EXTEND INTO SOUTHEASTERN NORTH DAKOTA THURSDAY NIGHT.
THIS WILL GENERATE CATEGORICAL PRECIP CHANCES NORTH WITH CHANCE POPS
CENTRAL...MAINLY AFTER MIDNIGHT. THE LATEST 00Z MODEL SUITE IS A
LITTLE FASTER THAN PREVIOUS RUNS AND PROGS THE BOUNDARY TO PUSH
SOUTH ACROSS THE STATE FRIDAY MORNING AND INTO SOUTH DAKOTA FRIDAY
AFTERNOON. SUBSEQUENTLY...THE PRECIP TYPE IS PROGGED TO TRANSITION
FROM A WINTRY MIX CENTRAL EARLY FRIDAY MORNING TO ALL SNOW BY MID TO
LATE FRIDAY MORNING. MADE ADJUSTMENTS TO THE HOURLY WX GRIDS
ACCORDINGLY.
THE SNOW CHANCES SHOULD TAPER OFF FROM WEST TO EAST FRIDAY NIGHT AS
HIGH PRESSURE BUILDS INTO THE REGION. A WEAK WAVE IN WESTERLY FLOW
ALOFT IS PROGGED TO GENERATE A SLIGHT CHANCE OF SNOW SATURDAY AND
SATURDAY NIGHT. HOWEVER...ACCUMULATIONS SHOULD BE LIGHT.
A MORE POTENT SHORTWAVE IS THEN PROGGED TO AFFECT THE NORTHERN
PLAINS SUNDAY/SUNDAY NIGHT/MONDAY. THE 00Z ECMWF CONTINUES TO BE
MORE AGGRESSIVE THAN THE GFS/GEM WITH RESPECT TO THE STRENGTH OF
THIS FEATURE. HOWEVER...THE ECMWF IS TRENDING FARTHER SOUTH WITH ITS
TRACK. GIVEN THE MODEL TO MODEL AND RUN TO RUN
INCONSISTENCIES...WENT WITH A BLEND OF SOLUTIONS AND INCREASED POPS
SUNDAY THROUGH MONDAY. HIGH PRESSURE BUILDING INTO THE REGION SHOULD
GENERATE COOL AND DRY CONDITIONS TUESDAY WITH BELOW NORMAL
TEMPERATURES EXPECTED.
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL ACROSS WESTERN AND CENTRAL
NORTH DAKOTA THROUGH THE TAF PERIOD. THERE IS A POTENTIAL FOR LOW
VFR CONDITIONS IN STRATUS AND SNOW AFTER 09 UTC ACROSS NORTHWEST
NORTH DAKOTA...POSSIBLY IMPACTING KISN BETWEEN 09 UTC AND 12 UTC.
FURTHERMORE...THERE WILL BE A SLIGHT CHANCE FOR A RAIN/SNOW MIX
NORTH (KISN/KMOT) LATE THIS AFTERNOON. HOWEVER...CONDITIONS SHOULD
REMAIN VFR.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...LTH
LONG TERM/AVIATION...TM
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
859 PM EDT THU MAR 14 2013
.DISCUSSION...WEAK DISTURBANCE SO FAR THIS EVENING HAS GENERATED AN
AREA OF WEAK RADAR RETURNS OVER MIDDLE TN. THIS ACTIVITY HAS
PRODUCED NOT MUCH MORE THAN SPRINKLES AT NASHVILLE TN AND BOWLING
GREEN KY. 18Z GFS AND LATEST RUC MODEL RUNS ARE SUGGESTING NOT MUCH
MORE THAN SPRINKLES OR FLURRIES FOR REST OF THE EVENING AND EARLY
MORNING HOURS. IN FACT...NOT EXPECTING MUCH AT ALL FOR SW VA AND FAR
NE TN. 15/00Z RNK SOUNDING WAS BONE DRY BELOW 700 MBS WITH DEW POINT
TEMPS IN THE TEENS ACROSS SW VA AND NE CORNER OF TN.
PLAN TO DROP ANY MENTION OF PRECIPITATION FOR SW VA AND NE TN...
MENTION SPRINKLES FOR NRN PLATEAU...AND KEEP SPRINKLES OR A 20
PERCENT CHANCE FOR SEQUATCHIE VALLEY AND CHA AREA FOR NEXT FEW
HOURS. WILL ALSO ADJUST SKY COVER AND HOURLY GRIDS AS NEEDED.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 36 70 47 73 50 / 10 0 10 20 30
KNOXVILLE MCGHEE TYSON AIRPORT, TN 34 65 47 70 49 / 10 0 20 30 40
OAK RIDGE, TN 34 66 47 69 48 / 20 0 20 30 50
TRI CITIES AIRPORT, TN 26 62 44 64 46 / 10 0 40 50 50
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
TG
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
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
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
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 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 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)
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 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 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...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 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 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
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
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 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 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
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