Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/02/13
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
349 PM MST THU FEB 28 2013
.SHORT TERM...MOISTURE CONTINUES TO INCREASE ACROSS MOUNTAINS AS
DISTURBANCE BEGINS TO MOVE INTO WESTERN COLORADO. MODERATE
NORTHWEST FLOW ALOFT PROVIDING DECENT OROGRAPHICS WITH OROGRAPHICS
AROUND 6 C/KM. MOUNTAIN WEB CAMS SHOWING SNOW SHOWERS BECOMING
MORE WIDESPREAD...MAINLY ALONG CONTINENTAL DIVIDE OF SUMMIT AND
GRAND COUNTIES AS WELL AS PARK AND GORE RANGES OF WESTERN JACKSON
COUNTY. SO FAR... ACCUMULATIONS MINIMAL BASED ON LATEST SNOTEL
DATA. WINDS HAVE BEEN GUSTY OVER THE HIGHER MOUNTAINS AND ALONG
FOOTHILLS AS WELL AS ACROSS SOUTH PARK. DISTURBANCE TO MOVE ACROSS
MOUNTAINS AND PLAINS THROUGH THE EVENING. LATEST RAP AND NAM QG
VERTICAL VELOCITY PROGS STILL INDICATING ASCENT TO BE MINIMAL...SO
MOUNTAIN SNOWFALL TO BE MAINLY OROGRAPHICALLY DRIVEN WITH SOME
HELP WITH INSTABILITY. ACCUMULATIONS OF 1 TO 4 INCHES STILL
LOOKING ON TRACK THOUGH SOME LOCATIONS ALONG THE FAVORED WEST AND
NORTHWEST ASPECTS COULD RECEIVE A COUPLE EXTRA INCHES. NORTHWEST
FLOW TO PROVIDE DOWNSLOPE IN AND NEAR FOOTHILLS SO SNOW SHOWERS
THERE WILL BE LIMITED. BUT THERE WILL BE SOME WIND GUSTS TO 50 MPH
DUE TO THE DOWNSLOPE. ACROSS PLAINS... SOUTHEAST WINDS DEVELOPED
IN THE DENVER AREA DUE TO WEAK ANTICYCLONE OVER SOUTHERN WELD
COUNTY. LATEST MODELS SHOWING THIS ANTICYCLONE SHIFTING EAST OF
THE DENVER AREA DURING THE EVENING AS DOWNSLOPE OFF FOOTHILLS
BEGINS TO DOMINATE FRONT RANGE. STILL THINKING THIS DOWNSLOPE FLOW
WILL LIMIT SNOW CHANCES ALONG URBAN CORRIDOR. MODELS STILL SHOWING
BEST CHANCE FOR SHOWERS TO BE EAST AND SOUTH OF DENVER...PAINTING
SOME LIGHT QPF AND SNOW ACCUMULATIONS. WILL UP THE POPS TO THE
CHANCE CATEGORY IN THIS AREA...KEEPING REST OF THE POPS AS IS.
LATEST CROSS SECTIONS INDICATE A GRADUAL DECREASE IN MOISTURE
AFTER MIDNIGHT. STILL GOOD OROGRAPHICS FOR CONTINUED MOUNTAIN SNOW
SHOWERS. CLOUD COVER AND WIND TO HELP MODERATE OVERNIGHT
TEMPERATURES. ON FRIDAY...FLOW ALOFT BECOMES A BIT MORE NORTHERLY
AS TROUGH MOVES INTO CENTRAL PLAINS. MOISTURE OVER MOUNTAINS
CONTINUES TO DRY OUT. OROGRAPHICS STILL FAVORABLE FOR MOUNTAIN
SNOW SHOWERS...THOUGH INCREASING STABILITY AND LACK OF LIFT WILL
LIMIT COVERAGE. PERHAPS ANOTHER INCH OR SO OF ACCUMULATION. ACROSS
PLAINS...SOME MID AND HIGH LEVEL CLOUDS TO PREVAIL. AIRMASS TO
WARM SLIGHTLY...SHOULD ALLOW TEMPERATURES TO WARM INTO THE 40S
ACROSS THE PLAINS...THOUGH SNOW COVER COULD KEEP TEMPERATURES IN
THE 30S. WINDS TO BE A BIT GUSTY ACROSS HIGHER RIDGES AND FAR
EASTERN PLAINS.
.LONG TERM...THE CWA WILL BE UNDER FAIRLY STRONG NORTHERLY FLOW
ALOFT BY FRIDAY EVENING AS A VERY FAST MOVING SHORT WAVE TROUGH
WHICH CLIPS THE HIGH PLAINS STATES EARLY FRIDAY MOVES OUT OF THE
AREA. THE 12Z NAM INDICATES A SECOND BUT VERY MINOR DISTURBANCE IN
THE NORTHERLY FLOW WHICH PROVIDES ADDITIONAL BUT SCANT MOISTURE TO
THE HIGH COUNTRY ALONG WITH ANOTHER PUSH OF STRONG NORTHWEST WINDS
ACROSS THE NORTHEAST PLAINS LATE FRIDAY INTO EARLY SATURDAY. DRY
DOWNSLOPE LOOKS TO BE THE RULE ONCE AGAIN WITH NO POPS EXPECETED
AT LOWER ELEVATIONS. IN THE HIGH COUNTRY...CROSS SECTIONS CONTINUE
TO SHOW SHALLOW MOISTURE BEING HELD AGAINST THE DIVIDE WITH
OROGRAPHICS DOING THE ONLY LIFTING FOR ANY SNOW SHOWERS. GFS-QG
FIELDS INDICATE NEUTRAL TO SLIGHT DOWNWARD MOTION FRIDAY EVE
THROUGH LATE SATURDAY AND SEE NO REASON TO BUMP THE POPS OVER THE
ISOLD SNOW SHOWERS CURRENTLY IN THE ZFP. BY MIDDAY/EVE SATURDAY
THE AMPLIFIED RIDGE OF HIGH PRESSURE WITH AN AXIS LOCATED OVER THE
EASTERN EDGE OF THE GREAT BASIN IS ALREADY WEAKENING OUT AHEAD OF
THE NEXT DISTURBANCE EXPECTED FOR THE NORTHERN COLO EARLY SUNDAY.
AS THE WEAKENING RIDGE MOVES OUT OVER THE CENTRAL US...TIGHT
PACKING IN THE MID/UPPER LEVEL HEIGHT FIELDS PROVIDES FOR SOME
BRIEF BUT STRONG WESTERLY FLOW ACROSS THE STATE ON SUNDAY.
SANGSTER HIGH WIND MODEL INDICATES POTENTIAL HIGH WIND CRITERIA
BEING MET FOR THE SUNDAY AFT/EVE. WILL BUMP UP WIND GRIDS FOR THIS
NOTIFICATION AND SHD BE WATCHED IN LATER RUNS. AFTER THIS
INFLECTION POINT IN THE FLOW ALOFT...LATEST GFS/CMC TRAJECTORY
WITH THIS NEXT FAST MOVING WAVE TAKES UPPER LOW OVER WESTERN MT
SOUTHEASTWARD OVER THE BLACK HILLS REGION OF SD AND INTO EAST CENT
NE BY MONDAY NIGHT. THIS WILL DO MUCH LIKE THE PREVIOUS WAVES
GIVING A BRIEF SHOT OF LIGHT SNOW TO THE NORTHERN AND CENT MTNS
WHILE PRODUCING DRY NORTHWEST DOWNSLOPE FLOW EAST OF THE DIVIDE.
ECM IS SLOWER WITH THE FEATURE BUT DRYER AND MORE NORTHERLY.
HOWEVER...HAVE ADJUSTED POP GRIDS AROUND THIS SUNDAY INTO EARLY
MONDAY TIME FRAME FOR THE MTN LOCATIONS FOR A LONGER PERIOD OF
LIGHT SNOW ASSOC WITH TROUGH.
LOOKING TOWARD THE TUESDAY THROUGH THURSDAY PERIOD...A WARM
STABLE RIDGE OF HIGH PRESSURE WILL CONTINUE TO DEVELOP OVER THE
WESTERN US WHILE MAXIMIZING IN THE TUESDAY EVENING TO EARLY
WEDNESDAY TIMEFRAME. WILL EXPECT TUE TO REMAIN COOL AND BREEZY IN
THE MORNING POST TROUGH THEN GOOD WARMING INTO TUESDAY AFTN AND THE
DAYS AHEAD. THIS RIDGE WILL LIKELY TAKE DAYTIME HIGHS WELL ABOVE
SEASONAL NORMALS AT LOWER ELEVATIONS FOR BOTH WED AND THURS AS
WARMER SOUTHWESTERLY FLOW ALOFT PREVAILS BOTH DAYS IN ADVANCE OF THE
NEXT LARGER AND COLDER WAVE BEYOND THURSDAY.
&&
.AVIATION...WEAK ANTICYCLONE NORTH OF DENVER...WITH SOUTHEAST
WINDS AT KDEN WHILE DOWNSLOPE WESTERLIES PREVAILING AT KBJC AND
KAPA. ANTICYCLONE EXPECTED TO MOVE SOUTHEAST OF DENVER DURING THE
EVENING...WITH WINDS SHIFTING TO THE NORTHWEST AT KDEN. CEILINGS
TO LOWER DURING THE EVENING...SHOULD REMAIN ABOVE 10000 FEET WITH
VFR CONDITIONS PREVAILING. SLIGHT CHANCE OF SNOW SHOWERS THIS
EVENING AS DISTURBANCE MOVES ACROSS. STILL THINKING THE BEST
CHANCE FOR SHOWERS WILL BE SOUTHEAST OF DENVER AS THE DOWNSLOPE
WIND SHOULD LIMIT THE SHOWERS. IF A SHOWER DOES OCCUR...IT SHOULD
BE LIGHT AND BRIEF WITH LITTLE OR NO ACCUMULATION. CEILINGS OF
AROUND 6000 FEET AGL COULD ACCOMPANY THE SHOWERS. FOR NOW WILL
LEAVE OUT OF THE TAFS. AFTER MIDNIGHT... WINDS TO SHIFT TO SOUTH
SOUTHWEST AS DRAINAGE DEVELOPS. SOUTHERLY WINDS TO PREVAIL THROUGH
THE DAY FRIDAY WITH SPEEDS LESS THAN 8 KTS. VFR TO CONTINUE.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....FREDIN
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1009 AM MST THU FEB 28 2013
.UPDATE...
&&
.SHORT TERM...CURRENT FORECASTS STILL SEEM ON TRACK. MODERATE
NORTHWEST FLOW CONTINUES AS MODELS STILL INDICATING WEAK MID LEVEL
DISTURBANCE MOVING ACROSS COLORADO TODAY. SOME PRECIPITATION
CURRENTLY OVER UTAH AND IDAHO. LATEST RAP AND NAM QG PROGS
INDICATING MINIMAL ASCENT AS DISTURBANCE PASSES OVERHEAD. LAPSE
RATES FAIRLY REASONABLE ALONG WITH DECENT MOUNTAIN OROGRAPHICS FOR
SNOW SHOWERS AFTER 21Z ONCE AIRMASS MOISTENS WITH SOME
ACCUMULATIONS...MAINLY DURING THE EVENING. AMOUNTS UP TO 4 INCHES
STILL SEEMS REASONABLE. ACROSS PLAINS...DOWNSLOPE FLOW TO KEEP
THINGS DRY THOUGH 00Z. STILL SOME QUESTION THIS EVENING ON THE
POTENTIAL FOR WEAK UPSLOPE FLOW ALONG FRONT RANGE WHICH COULD
INCREASE THE SNOW CHANCES. STILL LOOKING LIKE THE DOWNSLOPE WILL
PREVAIL...AND WILL MAINTAIN THE CURRENT POPS. BETTER CHANCE FOR
SHOWERS STILL EAST AND SOUTHEAST OF DENVER AWAY FROM THE
DOWNSLOPE AND IS WHERE THE LATEST MODELS ARE SHOWING THE QPF AND
LIGHT SNOW AMOUNTS. DOES NOT APPEAR TO BE A DECENT WEATHER
PRODUCER FOR THE PLAINS GIVEN THE MINIMAL ASCENT AND WILL MAINTAIN
THE SLIGHT POPS FOR THE EVENING. WILL CONTINUE TO MONITOR THE
DEVELOPMENT OF THIS SYSTEM TO SEE OF HIGHER POPS WILL BE NEEDED.
.AVIATION...CURRENT TAF TRENDS STILL SEEM ON TRACK. MODELS
CONTINUE TO HINT AT THE DEVELOPMENT OF A WEAK ANTICYCLONE THIS
AFTERNOON WHICH COULD SHIFT WINDS TO THE NORTHEAST OR EAST AT DEN
AND APA. FOR NOW WILL MAINTAIN THE NORTHWEST DIRECTION. CLOUDS TO
GRADUALLY INCREASE THIS AFTERNOON WITH CEILINGS AROUND 10000 FEET
BY 00Z. SIGHT CHANCE FOR A FEW SHOWERS THIS EVENING IN THE DENVER
AREA...MAINLY EAST AND SOUTHEAST OF THE AIRPORTS. IT STILL LOOKS
LIKE THE DOWNSLOPE WINDS WILL PREVAIL...LIMITING CHANCE FOR
SHOWERS AT THE AIRPORTS. THERE IS A SLIGHT CHANCE OF CEILINGS
AROUND 5000 FEET AGL WITH THE SHOWERS...WILL HOLD OFF IN INCLUDING
AT THIS TIME. IF SHOWERS DO AFFECT THE AIRPORT...THEY SHOULD BE
LIGHT AND BRIEF WITH LITTLE OR NO ACCUMULATION.
&&
.PREV DISCUSSION... /ISSUED 409 AM MST THU FEB 28 2013/
SHORT TERM...NORTH-NORTHWESTERLY FLOW ALOFT WILL BEGIN TO VEER TO
THE NORTH BY TONIGHT AS A 110 KT JET MOVES IN FROM THE PACIFIC
NORTHWEST. MOISTURE BROUGHT IN BY THIS SYSTEM WILL BEGIN
INCREASING SNOW OVER THE MOUNTAINS THIS MORNING. THERE IS NOT MUCH
UPWARD QG VERTICAL MOTION WITH THIS SYSTEM...BUT THE WIND
DIRECTION IS OPTIMAL FOR OROGRAPHICALLY FORCED SNOW OVER THE
MOUNTAINS. EXPECT 1-4 INCHES OF SNOW OVER THE HIGHER MOUNTAINS
THROUGH THE DAY AND INTO THE NIGHT HOURS. NORTHWEST FLOW TENDS TO
DOWNSLOPE OVER THE FOOTHILLS AND ADJACENT PLAINS...BUT FURTHER
EAST WILL HAVE A BETTER CHANCE TO SEE SNOW SHOWERS. MODEL
SOUNDINGS SHOW SOME INSTABILITY OUT THERE AND SATURATED PROFILES
FURTHER EAST. SOUNDINGS CLOSER TO THE FOOTHILLS KEEP IT DRY AT
LOWER LEVELS DUE TO THE EXPECTED DOWNSLOPING. THE WILD CARD IS THE
LOW LEVEL WINDS...AS A COUPLE MODELS ARE HINTING AT AN ANTICYCLONE
SETTING UP NEAR OR NORTH OF DENVER. IF THIS OCCURS...IT MAY HELP
TO BRING IN SOME MOISTURE WITH A SLIGHT UPSLOPE FLOW. WILL NEED TO
MONITOR THESE WINDS LATE THIS AFTERNOON. GUSTY NORTHWEST WINDS
WILL ACCOMPANY THE SHOWERS OVER THE PLAINS WITH GUSTS UP TO 25
MPH. THE MOUNTAINS AND UPPER FOOTHILLS WILL SEE STRONGER
WINDS...WITH SPEEDS AROUND 15 TO 30 MPH WITH GUSTS AS HIGH AS 50
MPH. A BRIEF LOOK AT THIS PATTERN MAY LOOK LIKE WHAT OCCURRED LAST
TUESDAY...BUT WE HAVE NO WHERE NEAR THE LIFT WE HAD THAT DAY. QG
VERTICAL MOTION VALUES WERE NEAR -35 UPWARD...WHERE AS TODAY WE
ARE RIGHT AROUND 0. THE JET IS MOVING OVERHEAD HOWEVER...SO THAT
CAN ALWAYS PLAY INTO AMOUNTS. WILL INCREASE POPS OVER THE PLAINS
MAINLY ALONG AND SOUTH OF I70 AND KEEP AMOUNTS LIGHT FOR NOW. MAX
TEMPERATURES TODAY WILL BE SLIGHTLY HIGHER THAN YESTERDAY...WITH
MID TO UPPER 30S FOR THE PLAINS AND 20S FOR THE MOUNTAINS.
MOISTURE WILL BE DECREASING AFTER MIDNIGHT WITH ONLY HIGH CLOUDS
EXPECTED. THIS...ALONG WITH NORTHWEST WINDS REMAINING A BIT
GUSTY...WILL HELP MODERATE MINIMUM TEMPERATURES TONIGHT. WINDS
WILL REMAIN GUSTY OVER THE MOUNTAINS AS WELL...WITH GUSTS UP TO
50 MPH.
LONG TERM...STILL EXPECT ENOUGH MOISTURE AND GOOD OROGRAPHIC FLOW
IN THE MOUNTAINS FOR SNOW SHOWERS TO CONTINUE INTO FRIDAY. ANY
ACCUMULATION WILL BE LIMITED BY INCREASING STATIC STABILITY WITH
AMOUNTS AN INCH OR LESS. ON THE PLAINS...SOME MID/UPPER LEVEL
CLOUDS CAN BE EXPECTED ALTHOUGH SHOULD BE PLENTY OF BREAKS AS WELL
TO ALLOW A DECENT WARMUP.
FOR SATURDAY AND SUNDAY...WARMING TREND WILL CONTINUE WITH
WESTERLY FLOW ALOFT AND SIGNIFICANT MID LEVEL WARMING. 700 MB
TEMPS RISE TO NEAR 0C BY LATE SATURDAY...AND THEN NEAR 2C BY
EARLY SUNDAY. DESPITE SNOW COVER...WE ARE ENTERING MARCH AND
SUNSHINE WILL HAVE MORE EFFECT ON TEMPS. WILL STILL BE A LITTLE
CONSERVATIVE WITH HIGH TEMPS SATURDAY ESPECIALLY EAST OF DENVER
WHERE SLIGHTLY DEEPER INVERSIONS WILL EXIST. THEN EXPECT FURTHER
MODERATION SUNDAY WITH THINNING SNOW COVER AND STRONGER DOWNSLOPE
FLOW AND BETTER MIXING.
BY SUNDAY AFTERNOON...LIFT AND COLD ADVECTION FROM THE NEXT
APPROACHING DISTURBANCE SHOULD REACH THE MOUNTAINS WITH SNOW
DEVELOPING. LATEST GFS...MOST GFS ENSEMBLES...AND ECMWF ARE IN
REASONABLE AGREEMENT WITH TIMING AND LOCATION. THIS WOULD BRING
SNOW TO THE MOUNTAINS FROM SUNDAY AFTERNOON THROUGH SUNDAY
NIGHT...AND ALSO POTENTIAL FOR STRONG WINDS ACROSS THE PLAINS FROM
LATE SUNDAY NIGHT INTO MONDAY IN THIS SYSTEMS WAKE. AS A RESULT...
WE HAVE INCREASED SNOW IN THE HIGH COUNTRY AND WINDS FROM THE
FRONT RANGE DOWN ACROSS ALL OF THE PLAINS. THERE IS JUST A SLIGHT
CHANCE THE UPPER TROUGH COULD DIG A BIT MORE FOR LESS WIND AND A
CHANCE OF PRECIP ON THE PLAINS...SO WILL CONTINUE TO MONITOR THIS
SYSTEM OVER THE NEXT COUPLE DAYS.
AFTER THIS SYSTEM...A HIGH AMPLITUDE UPPER LEVEL RIDGE WILL BUILD
BACK ACROSS THE CENTRAL ROCKIES FOR TUESDAY AND WEDNESDAY. THIS
WILL BRING MORE SPRING-LIKE WEATHER WITH HIGHS PUSHING THE 60S BY
WEDNESDAY.
AVIATION...VFR CONDITIONS TO CONTINUE THIS MORNING WITH AN INCREASE
IN MID AND HIGH LEVEL CLOUDS. DRAINAGE WINDS EXPECTED TO BECOME
NORTHWEST AROUND 16Z...WITH THE POSSIBILITY OF ANOTHER WEAK
ANTICYCLONE DEVELOPING NORTH OF DENVER. THIS COULD SHIFT WINDS TO
A NORTHEAST DIRECTION. FOR NOW WILL MAINTAIN THE NORTHWEST
DIRECTION WITH SPEEDS AROUND 8 KTS...BUT MAY NEED TO SWITCH THEM
OVER TO A NORTHEAST DIRECTION DEPENDING ON HOW WELL MIXED THE
ATMOSPHERE BECOMES. CEILINGS TO GRADUALLY LOWER DURING THE
AFTERNOON...SHOULD REMAIN ABOVE 10000 FEET AGL. A FEW SNOW SHOWERS
COULD DEVELOP AFTER 00Z. AT THIS TIME IT LOOKS LIKE THE DOWNSLOPE
NORTHWEST WINDS WILL HINDER THE DEVELOPMENT AND ANY SNOW SHOWER
ACTIVITY SHOULD REMAIN EAST OF THE AIRPORTS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....BARJENBRUCH
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
925 PM EST FRI MAR 1 2013
.DISCUSSION...
ANOTHER QUIET WX NIGHT AS A STRONG H30-H20 JET STREAK OVER THE SERN
CONUS PULLS A DENSE MID/UPR LVL CLOUD DECK ACRS THE STATE. THE DECK
EXTENDS BACK TO THE BAY OF CAMPECHE AND IS EMBEDDED WITHIN A DEEP
W/SW FLOW...SO NO CHANCE FOR CLEARING OVERNIGHT. IN ADDITION...
LATEST RAP ANALYSIS SHOWS A RATHER TIGHT SFC PGRAD OVER THE ERN
GOMEX/NRN BAHAMAS THAT WILL MAINTAIN A LIGHT BUT STEADY W/NW SFC/LOW
LVL FLOW.
RAP SHOWS A SHALLOW SFC/LOW LVL THERMAL TROF OVER THE ERN GOMEX THAT
WILL SUPPORT SOME COOL AIR ADVECTION OVERNIGHT. HOWEVER...THE
COMBINATION OF WINDS AND CLOUD COVER WILL ALL BUT ELIMINATE THE
POTENTIAL FOR ANY SIGNIFICANT RADIATIONAL COOLING. WILL UPDATE THE
ZONES TO BRING SKIES UP TO CLOUDY...ALSO WILL BUMP MIN TEMPS UP A
FEW DEGS.
&&
.AVIATION...
THRU 03/00Z...VFR ALL SITES...CIGS AOA FL120. AFT 02/17Z...W/NW SFC
WND G22KTS.
&&
.MARINE...
LCL C-MAN/DATA BUOY NETWORK SHOWS WINDS HAVE DIMINISHED TO A LIGHT
TO GENTLE NWRLY BREEZE ACRS THE LCL ATLC. WINDS AREA EXPECTED TO
PICK BACK UP AGAIN OVERNIGHT...HOWEVER...AS A RELATIVELY TIGHT PGRAD
OVER THE ERN GOMEX WORKS ITS WAY ACRS THE STATE. INDEED...THE USAF
915HZ CAPE PROFILER MEASURED WINDS THRU 4KFT INCREASING FROM
10-15KTS TO 15-20KTS SINCE SUNSET...VAD WIND PROFILER FROM THE KTBW
RADAR SHOWS A SOLID 15-20KTS NW FLOW THRU 4KFT.
THE OFFSHORE BREEZE IS REFLECTED IN THE SEA STATE THIS EVNG...FETCH
PROTECTED NEARSHORE BUOYS MEASURING 2-3FT SEAS IN A 12-13SEC PD
SWELL. WIND WAVES ARE MORE PREVALENT AT THE OFFSHORE BUOYS...
MEASURING 3-4FT SEAS WITH DOMINANT PDS BTWN 6-8SEC. EXPECT
CONDITIONS TO DETERIORATE AREAWIDE AS SFC/BNDRY LYR WINDS PICK UP
OVERNIGHT...BUT SHOULD REMAIN BLO SCA CRITERIA. WILL GO WITH
CAUTIONARY STATEMENTS ALL ZONES.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...BRAGAW
LONG TERM/IMPACT WX...KELLY
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
916 PM EST FRI MAR 1 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 257 PM EST FRI MAR 1 2013
ONE LAST DISTURBANCE SLIDING AROUND THE PERIPHERY OF THE LARGE UPPER
LOW TO THE NORTHEAST WILL PUSH THROUGH THE REGION EARLY THIS
EVENING...WITH CONTINUED POTENTIAL FOR LIGHT SNOW SHOWERS OR
FLURRIES IN PORTIONS OF THE SOUTHERN FORECAST AREA. HIGH PRESSURE AT
THE SURFACE WILL RETURN DRY WEATHER TO THE AREA THROUGH THE WEEKEND.
ANOTHER DISTURBANCE IN NORTHWEST FLOW ALOFT MAY PUSH THROUGH THE
AREA EARLY NEXT WEEK...MONDAY NIGHT THROUGH TUESDAY NIGHT WITH
ADDITIONAL PRECIPITATION CHANCES ASSOCIATED WITH IT. HIGH
PRESSURE...DRY WEATHER AND WARMER TEMPERATURES ARE IN STORE FOR THE
END OF NEXT WEEK.
&&
.NEAR TERM /TONIGHT/...
ISSUED AT 257 PM EST FRI MAR 1 2013
PER LATEST RADAR MOSAIC TRENDS AND MOST RECENT HRRR RUN DEPICT SNOW
SHOWERS/FLURRIES AND EVEN SOME DRIZZLE ACROSS THE SOUTH WILL BE A
LITTLE SLOWER IN EXITING THE FORECAST AREA. LEFT IN LOW CHANCES FOR
PRECIP ACROSS THE SOUTH FOR THIS EVENING...THEN WENT DRY FOR THE
OVERNIGHT. BASED ON PERSISTENCE AND THE FACT THAT CLOUDS AND EVEN TO
SOME EXTENT SOME PRECIPITATION WILL HANG AROUND A WHILE
LONGER...BUMPED UP OVERNIGHT LOWS ABOUT 5 DEGREES ABOVE MOS WHICH
YIELDS LOWS IN THE MID TO UPPER 20S.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
ISSUED AT 257 PM EST FRI MAR 1 2013
IT/S LOOKING LIKE A DRY WEEKEND. SURFACE HIGH PRESSURE WILL BUILD
OVER THE AREA AND REMAIN THE DOMINANT WEATHER FIXTURE FOR THE
WEEKEND. MOSTLY CLOUDY SKIES APPEAR TO LINGER OVER CENTRAL INDIANA
FOR THE FIRST HALF OF THE WEEKEND BUT THE COLUMN FINALLY BEGINS TO
DRY OUT BY SUNDAY...ALLOWING MOSTLY SUNNY TO PARTLY CLOUDY SKIES TO
RETURN TO THE AREA. NORTHERLY FLOW WILL KEEP TEMPERATURE BELOW
NORMAL THROUGH THE WEEKEND. NEXT SYSTEM TO IMPACT THE REGION COME
SOMETIME MONDAY OR MONDAY NIGHT. THERE A STARK DIFFERENCE WITH
RESPECT TO TIMING...WITH THE GFS BEING QUITE A FAST AND PROGRESSIVE
OUTLIER...SO LEANED TOWARD THE REST OF THE SLOWER GUIDANCE AND ONLY
INTRODUCED LOW CHANCE POPS LATE IN THE DAY MONDAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
ISSUED AT 257 PM EST FRI MAR 1 2013
THE EXTENDED PERIOD WILL START OUT RATHER ACTIVE AS A SURFACE LOW
FROM THE SOUTHERN PLAINS EVENTUALLY MERGES WITH AN UPPER LEVEL LOW
COMING OUT OF THE NORTHERN PLAINS ON TUESDAY. THE SURFACE LOW WILL
REACH CENTRAL INDIANA FIRST THOUGH BRINGING RAIN AND SNOW CHANCES ON
MONDAY. THE GFS AND EURO CONTINUE TO DIFFER ON TRACK OF UPPER LEVEL
LOW WITH THE GFS DIGGING IT FURTHER INTO THE TENNESSEE VALLEY WHILE
STRENGTHENING IT. MEANWHILE...THE EURO TAKES IT ACROSS CENTRAL
INDIANA AND NOT AS TIGHTLY WRAPPED. FOR NOW...WILL STICK WITH
INITIALIZATION WHICH SEEMS TO BE FAVORING THE GFS A TAD BY
INDICATING LIKELY POPS ACROSS THE SOUTHEAST PORTIONS OF CENTRAL
INDIANA ON TUESDAY.
PRECIP WILL DIMINISH FROM WEST TO EAST ON TUESDAY NIGHT/WEDNESDAY
MORNING WITH ALL PRECIP OUT OF THE AREA BY WEDNESDAY AFTERNOON.
THAT/S WHEN A LARGE RIDGE WILL MOVE INTO CENTRAL INDIANA BRINGING
DRY WEATHER FOR THE REMAINDER OF THE LONG TERM PERIOD. TEMPS WILL
BE SLIGHTLY BELOW NORMAL AT FIRST...BUT WARM UP BY THE END OF THE
EXTENDED PERIOD. INITIALIZATION NUMBERS LOOK REASONABLE...SO WILL
NOT DEVIATE.
&&
.AVIATION /DISCUSSION FOR THE 020300Z KIND TAF UPDATE/...
ISSUED AT 916 PM EST FRI MAR 1 2013
MVFR CEILINGS HAVE SCATTERED OUT INTO A VFR DECK 040-050 AT KIND.
SURROUNDING OBSERVATIONS INDICATE THAT THIS IS PROBABLY
TEMPORARY...WITH A RETURN TO THE LOWER CEILINGS SOON.
THEREFORE...WILL HOLD ONTO THE MVFR CEILINGS ON THE UPDATE FOR NOW.
PREVIOUS DISCUSSION FOLLOWS.
WEAK SURFACE TROUGH CURRENTLY PUSHING SOUTH THROUGH THE SOUTHERN
SECTIONS OF THE FORECAST AREA. AREAS OF IFR CEILINGS/VISIBILITIES IN
LIGHT SNOW/DRIZZLE ASSOCIATED WITH THIS FEATURE..SO EXPECTING THESE
CONDITIONS TO AFFECT KHUF/KBMG THROUGH ABOUT 020200Z.
OTHERWISE...LARGE AREA OF MVFR CEILINGS AROUND 020 ACROSS THE OHIO
VALLEY EXPECTED TO LINGER TONIGHT UNDER AN INVERSION BELOW 035-040.
SURFACE WINDS GENERALLY UNDER 10 KTS AT THE TAF SITES THROUGH
021200Z.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...SMF
NEAR TERM...SMF
SHORT TERM...SMF
LONG TERM....TDUD
AVIATION...JAS
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
847 AM EST THU FEB 28 2013
.SYNOPSIS...
LOW PRESSURE WILL DRIFT EAST FROM THE GREAT LAKES TO NEW ENGLAND
THROUGH THE END OF THE WEEK. AN UPPER LEVEL TROUGH WILL THEN
PERSIST OVER THE EASTERN STATES THROUGH THE WEEKEND. HIGH PRESSURE
IS EXPECTED EARLY NEXT WEEK. LOW PRESSURE LOOKS TO APPROACH THE
MID-ATLANTIC AROUND THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
WITH A LARGE UPPER CLOSED LOW HANGING OVER THE GREAT LAKES AND UPPER
MIDWEST...CONTINUED WAVES OF CLOUDS AND PERIODIC SHOWERS WILL SLIDE
OVER THE REGION. THE WARM SIDE OF THE SYSTEM MOVED ACROSS THE REGION
ON TUE...BUT IS NOW WELL NORTH AND EAST OF THE AREA. AT THIS
POINT...THE MID ATLC IS ON THE SOUTHEASTERN QUADRANT OF THIS LARGE
ENCOMPASSING UPPER FEATURE. MUCH SMALLER-SCALE WAVES OF WEAK LIFT
AND MOISTURE CONVERGENCE HAVE BEEN AND WILL CONTINUE TO GENERATE
LIGHT SHOWERS ACROSS THE LOWLANDS AND MINOR ACCUMULATIONS OF UPSLOPE
SNOW SHOWERS FOR THE MTNS. SAME STORY AT THE MOMENT...W/ BATCHES OF
LIGHT RAIN DEVELOPING OVER THE VA/MD PIEDMONT SINCE MIDNIGHT. SOME
LIGHT SHOWERS WILL AFFECT THE DC/BALT AREAS AND BACK TOWARD THE BLUE
RIDGE...SLOWLY DRIFTING TOWARD THE EAST THRU DAWN.
NEAR TERM GUIDANCE...ESPEC THE HRRR WHICH RECENT RUNS APTLY DEPICTED
THE CURRENT ACTIVITY...SHOW ANOTHER BATCH OF MOISTURE CONVERGENCE
ACROSS THE I-95 CORRIDOR LATER THIS MRNG - TOWARD EARLY AFTN. THIS
WOULD LEAVE A DRY MORNING FROM AROUND DAWN THRU AROUND NOON BEFORE
THE NEXT BATCH OF SCATTERED SHOWERS DEVELOPS. RELATIVELY MILD
OVERNIGHT LOWS IN THE U30S-L40S WILL GRADUALLY RISE TOWARD THE U40S
TO AROUND 50 BY MID AFTN. WLY WINDS WILL AGAIN PICK UP IN THE
AFTN...ONLY CUTTING DOWN THE APPARENT TEMPS BY A FEW DEGREES BUT NOT
PARTICULARLY WINDY - MAINLY A 15-20MPH BREEZE.
BACKING OUT TO A LARGER VIEW AGAIN - THE PARENT UPPER LOW WILL BE
MAKING A SLOW/STEADY WOBBLE TOWARD THE SE OVER THE COURSE OF TODAY
AND INTO TONIGHT FROM UPSTATE NY. ONE OF THE MORE POTENT UPPER VORT
MAXES ASSOCIATED W/ THIS FEATURE WILL BE SWINGING DOWN AROUND THE
BACKSIDE OF THE LOW - DIRECTLY OVER THE REGION LATER TONIGHT. A
BRIEF PERIOD OF GUSTY NW WINDS WILL MOVE OVER THE AREA OVERNIGHT AND
HELP PUSH THE EARLIER PRECIP WELL OFF THE COAST AND DRY OUT THE
REGION HEADING INTO FRI.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
A CUTOFF LOW WILL REMAIN OVER NEW ENGLAND FRIDAY THROUGH FRIDAY
NIGHT WHILE THE UPPER-LEVEL TROUGH ASSOCIATED WITH THIS SYSTEM
REMAINS OVERHEAD.
A NORTHWEST FLOW BETWEEN SURFACE LOW PRESSURE NEAR THE CANADIAN
MARITIMES AND HIGH PRESSURE OVER THE CENTRAL CONUS WILL ALLOW FOR
CHILLY CONDITIONS. MAX TEMPS FRIDAY WILL RANGE FROM THE 20S IN
PORTIONS OF THE ALLEGHENY HIGHLANDS TO THE MIDDLE AND UPPER 40S NEAR
WASHINGTON AND BALTIMORE. MIN TEMPS FRIDAY NIGHT WILL RANGE FROM THE
TEENS IN THE ALLEGHENY HIGHLANDS TO THE LOWER AND MIDDLE 30S IN
DOWNTOWN WASHINGTON/BALTIMORE.
A BKN STRATO CU WILL CAUSE PARTLY TO MOSTLY CLOUDY SKIES. DRIER AIR
ASSOCIATED WITH THE NORTHWEST FLOW WILL KEEP DRY CONDITIONS ACROSS
THE REGION FOR MOST OF THE TIME. HOWEVER...A FEW SPRINKLES AND
FLURRIES ARE POSSIBLE FRIDAY AFTERNOON DUE TO LIMITED INSTABILITY
ASSOCIATED WITH DAYTIME HEATING.
FOR LOCATIONS ALONG AND WEST OF THE ALLEGHENY FRONT. AN UPSLOPE
COMPONENT TO THE LOW-LEVEL FLOW WILL LIKELY TRIGGER SNOW SHOWERS.
ACCUMULATIONS DURING THE DAY FRIDAY SHOULD BE LIGHT. SNOW SHOWERS
ARE POSSIBLE FRIDAY NIGHT...BUT ANY ACCUMULATION WILL BE LIGHT.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
UPR TROUGH AXIS DRIFTS EAST ACROSS THE MID-ATLANTIC SATURDAY THROUGH
SUNDAY WITH SFC PRESSURE BUILDING FROM THE WEST BEHIND THE AXIS.
BELOW NORMAL TEMPERATURES EXPECTED UNDER THE CANADIAN SOURCED
AIR...THOUGH ONLY 5 TO 10 DEGREES BELOW. MAX TEMPS LOW TO MID 40S
SATURDAY...THEN UPR 30S TO LOW 40S SUNDAY. DRY.
THE NEXT LOW LOOKS TO TRACK ACROSS THE MID-SOUTH STATES EARLY NEXT
WEEK AND IMPACT THE MID-ATLANTIC IN THE MIDDLE OF THE WEEK. WAY TOO
EARLY TO TAKE AN OPERATIONAL RUN VERBATIM /AKA THE 00Z ECMWF/...SO
WILL SIMPLY HAVE TO MONITOR THE POTENTIAL FOR LATE SEASON SNOW AS
THE DAYS PROGRESS.
&&
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
PLENTY OF CLOUD COVER OVERNIGHT AND THRU THE DAY TODAY. A FEW
SHOWERS WILL DRIFT OVER THE DC/BALT AREA THRU AROUND 12Z BUT THEN
DRY OUT FOR A FEW HRS. ANOTHER ROUND OF LIGHT SHOWERS EXPECTED
TOWARD THE EARLY AFTN HRS...LAST FOR A FEW HRS THEN ALSO DISSIPATE
AND EXIT TO THE EAST. A FEW NEAR 20KT GUSTS WILL AFFECT THE WRN HALF
OF THE AREA THIS AFTN...INCLUDING THE FOOTHILLS OF THE BLUE RIDGE
TOWARD KCHO AND KIAD. A GENERAL W-NW WIND WILL CONTINUE THRU THE
CURRENT TAF CYCLE.
VFR CONDITIONS ARE EXPECTED MOST OF THE TIME FRIDAY THROUGH THE
WEEKEND. HOWEVER...A BKN STRATOCU DECK MAY APPROACH 3KFT AT TIMES.
NORTHWEST WINDS ARE EXPECTED THROUGH THE PERIOD WITH GUSTS AROUND 15
TO 25 KNOTS.
&&
.MARINE...
LIGHT WINDS OVER THE WATERS...THOUGH SOME MARGINAL SCA GUSTS MAY
APPEAR DURING THE DAYTIME HRS TODAY. A GENERAL 10-15KT WLY BREEZE
WILL BE STEADY...BUT THE HIGHER GUSTS SHOULD HOLD OFF UNTIL
OVERNIGHT AND INTO EARLY FRI MRNG.
A NORTHWEST FLOW BETWEEN LOW PRESSURE NEAR THE CANADIAN MARITIMES
AND HIGH PRESSURE OVER THE CENTRAL CONUS WILL CONTINUE FRIDAY
THROUGH THE WEEKEND. A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE
WATERS FRIDAY AND THE SMALL CRAFT ADVISORY MAY NEED TO BE EXTENDED
INTO SATURDAY FOR PORTIONS OF THE WATERS.
HIGH PRESSURE WILL BUILD TOWARD THE WATERS EARLY NEXT WEEK.
&&
.TIDES/COASTAL FLOODING...
A COASTAL FLOOD ADVISORY HAS BEEN ISSUED FOR THE TIDAL POTOMAC AT
ALEXANDRIA THIS MORNING...WHERE MINOR FLOODING IS EXPECTED AT HIGH
TIDE. IN SPITE OF NW WINDS...POSITIVE ANOMALIES HAVE NOT RECEDED
TO A LARGE DEGREE...IN FACT - MOST SITES ARE STILL AROUND OR JUST
BELOW ONE FT ABOVE AVG. THIS WILL KEEP AN ELEVATED RISK OF NEAR-
MINOR THRESHOLDS FOR THE NEXT HIGH TIDE CYCLE. BESIDES
ALEXANDRIA...NO OTHER SINGLE FORECAST POINT HAS FORECAST CRITERIA
BEING REACHED...THOUGH MOST ARE FAIRLY CLOSE. WILL CONTINUE TO
MONITOR THESE TRENDS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...COASTAL FLOOD ADVISORY UNTIL NOON EST TODAY FOR VAZ054.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST FRIDAY FOR ANZ530-
531-535-536-538-539.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST
FRIDAY FOR ANZ532>534-537-540>543.
&&
$$
SYNOPSIS...BAJ
NEAR TERM...GMS
SHORT TERM...BJL
LONG TERM...BAJ
AVIATION...BJL/GMS
MARINE...BJL/GMS
TIDES/COASTAL FLOODING...KCS
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
317 AM EST THU FEB 28 2013
.SYNOPSIS...
LOW PRESSURE WILL DRIFT EAST FROM THE GREAT LAKES TO NEW ENGLAND
THROUGH THE END OF THE WEEK. AN UPPER LEVEL TROUGH WILL THEN
PERSIST OVER THE EASTERN STATES THROUGH THE WEEKEND. HIGH PRESSURE
IS EXPECTED EARLY NEXT WEEK. LOW PRESSURE LOOKS TO APPROACH THE
MID-ATLANTIC AROUND THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
WITH A LARGE UPPER CLOSED LOW HANGING OVER THE GREAT LAKES AND UPPER
MIDWEST...CONTINUED WAVES OF CLOUDS AND PERIODIC SHOWERS WILL SLIDE
OVER THE REGION. THE WARM SIDE OF THE SYSTEM MOVED ACROSS THE REGION
ON TUE...BUT IS NOW WELL NORTH AND EAST OF THE AREA. AT THIS
POINT...THE MID ATLC IS ON THE SOUTHEASTERN QUADRANT OF THIS LARGE
ENCOMPASSING UPPER FEATURE. MUCH SMALLER-SCALE WAVES OF WEAK LIFT
AND MOISTURE CONVERGENCE HAVE BEEN AND WILL CONTINUE TO GENERATE
LIGHT SHOWERS ACROSS THE LOWLANDS AND MINOR ACCUMULATIONS OF UPSLOPE
SNOW SHOWERS FOR THE MTNS. SAME STORY AT THE MOMENT...W/ BATCHES OF
LIGHT RAIN DEVELOPING OVER THE VA/MD PIEDMONT SINCE MIDNIGHT. SOME
LIGHT SHOWERS WILL AFFECT THE DC/BALT AREAS AND BACK TOWARD THE BLUE
RIDGE...SLOWLY DRIFTING TOWARD THE EAST THRU DAWN.
NEAR TERM GUIDANCE...ESPEC THE HRRR WHICH RECENT RUNS APTLY DEPICTED
THE CURRENT ACTIVITY...SHOW ANOTHER BATCH OF MOISTURE CONVERGENCE
ACROSS THE I-95 CORRIDOR LATER THIS MRNG - TOWARD EARLY AFTN. THIS
WOULD LEAVE A DRY MORNING FROM AROUND DAWN THRU AROUND NOON BEFORE
THE NEXT BATCH OF SCATTERED SHOWERS DEVELOPS. RELATIVELY MILD
OVERNIGHT LOWS IN THE U30S-L40S WILL GRADUALLY RISE TOWARD THE U40S
TO AROUND 50 BY MID AFTN. WLY WINDS WILL AGAIN PICK UP IN THE
AFTN...ONLY CUTTING DOWN THE APPARENT TEMPS BY A FEW DEGREES BUT NOT
PARTICULARLY WINDY - MAINLY A 15-20MPH BREEZE.
BACKING OUT TO A LARGER VIEW AGAIN - THE PARENT UPPER LOW WILL BE
MAKING A SLOW/STEADY WOBBLE TOWARD THE SE OVER THE COURSE OF TODAY
AND INTO TONIGHT FROM UPSTATE NY. ONE OF THE MORE POTENT UPPER VORT
MAXES ASSOCIATED W/ THIS FEATURE WILL BE SWINGING DOWN AROUND THE
BACKSIDE OF THE LOW - DIRECTLY OVER THE REGION LATER TONIGHT. A
BRIEF PERIOD OF GUSTY NW WINDS WILL MOVE OVER THE AREA OVERNIGHT AND
HELP PUSH THE EARLIER PRECIP WELL OFF THE COAST AND DRY OUT THE
REGION HEADING INTO FRI.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
A CUTOFF LOW WILL REMAIN OVER NEW ENGLAND FRIDAY THROUGH FRIDAY
NIGHT WHILE THE UPPER-LEVEL TROUGH ASSOCIATED WITH THIS SYSTEM
REMAINS OVERHEAD.
A NORTHWEST FLOW BETWEEN SURFACE LOW PRESSURE NEAR THE CANADIAN
MARITIMES AND HIGH PRESSURE OVER THE CENTRAL CONUS WILL ALLOW FOR
CHILLY CONDITIONS. MAX TEMPS FRIDAY WILL RANGE FROM THE 20S IN
PORTIONS OF THE ALLEGHENY HIGHLANDS TO THE MIDDLE AND UPPER 40S NEAR
WASHINGTON AND BALTIMORE. MIN TEMPS FRIDAY NIGHT WILL RANGE FROM THE
TEENS IN THE ALLEGHENY HIGHLANDS TO THE LOWER AND MIDDLE 30S IN
DOWNTOWN WASHINGTON/BALTIMORE.
A BKN STRATO CU WILL CAUSE PARTLY TO MOSTLY CLOUDY SKIES. DRIER AIR
ASSOCIATED WITH THE NORTHWEST FLOW WILL KEEP DRY CONDITIONS ACROSS
THE REGION FOR MOST OF THE TIME. HOWEVER...A FEW SPRINKLES AND
FLURRIES ARE POSSIBLE FRIDAY AFTERNOON DUE TO LIMITED INSTABILITY
ASSOCIATED WITH DAYTIME HEATING.
FOR LOCATIONS ALONG AND WEST OF THE ALLEGHENY FRONT. AN UPSLOPE
COMPONENT TO THE LOW-LEVEL FLOW WILL LIKELY TRIGGER SNOW SHOWERS.
ACCUMULATIONS DURING THE DAY FRIDAY SHOULD BE LIGHT. SNOW SHOWERS
ARE POSSIBLE FRIDAY NIGHT...BUT ANY ACCUMULATION WILL BE LIGHT.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
UPR TROUGH AXIS DRIFTS EAST ACROSS THE MID-ATLANTIC SATURDAY THROUGH
SUNDAY WITH SFC PRESSURE BUILDING FROM THE WEST BEHIND THE AXIS.
BELOW NORMAL TEMPERATURES EXPECTED UNDER THE CANADIAN SOURCED
AIR...THOUGH ONLY 5 TO 10 DEGREES BELOW. MAX TEMPS LOW TO MID 40S
SATURDAY...THEN UPR 30S TO LOW 40S SUNDAY. DRY.
THE NEXT LOW LOOKS TO TRACK ACROSS THE MID-SOUTH STATES EARLY NEXT
WEEK AND IMPACT THE MID-ATLANTIC IN THE MIDDLE OF THE WEEK. WAY TOO
EARLY TO TAKE AN OPERATIONAL RUN VERBATIM /AKA THE 00Z ECMWF/...SO
WILL SIMPLY HAVE TO MONITOR THE POTENTIAL FOR LATE SEASON SNOW AS
THE DAYS PROGRESS.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
PLENTY OF CLOUD COVER OVERNIGHT AND THRU THE DAY TODAY. A FEW
SHOWERS WILL DRIFT OVER THE DC/BALT AREA THRU AROUND 12Z BUT THEN
DRY OUT FOR A FEW HRS. ANOTHER ROUND OF LIGHT SHOWERS EXPECTED
TOWARD THE EARLY AFTN HRS...LAST FOR A FEW HRS THEN ALSO DISSIPATE
AND EXIT TO THE EAST. A FEW NEAR 20KT GUSTS WILL AFFECT THE WRN HALF
OF THE AREA THIS AFTN...INCLUDING THE FOOTHILLS OF THE BLUE RIDGE
TOWARD KCHO AND KIAD. A GENERAL W-NW WIND WILL CONTINUE THRU THE
CURRENT TAF CYCLE.
VFR CONDITIONS ARE EXPECTED MOST OF THE TIME FRIDAY THROUGH THE
WEEKEND. HOWEVER...A BKN STRATOCU DECK MAY APPROACH 3KFT AT TIMES.
NORTHWEST WINDS ARE EXPECTED THROUGH THE PERIOD WITH GUSTS AROUND 15
TO 25 KNOTS.
&&
.MARINE...
LIGHT WINDS OVER THE WATERS...THOUGH SOME MARGINAL SCA GUSTS MAY
APPEAR DURING THE DAYTIME HRS TODAY. A GENERAL 10-15KT WLY BREEZE
WILL BE STEADY...BUT THE HIGHER GUSTS SHOULD HOLD OFF UNTIL
OVERNIGHT AND INTO EARLY FRI MRNG.
A NORTHWEST FLOW BETWEEN LOW PRESSURE NEAR THE CANADIAN MARITIMES
AND HIGH PRESSURE OVER THE CENTRAL CONUS WILL CONTINUE FRIDAY
THROUGH THE WEEKEND. A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE
WATERS FRIDAY AND THE SMALL CRAFT ADVISORY MAY NEED TO BE EXTENDED
INTO SATURDAY FOR PORTIONS OF THE WATERS.
HIGH PRESSURE WILL BUILD TOWARD THE WATERS EARLY NEXT WEEK.
&&
.TIDES/COASTAL FLOODING...
MOST OF THE BAY/TP SITES EITHER IN LOW TIDE OR HEADING OUT OF THE
OVERNIGHT LOW TIDE CYCLES. POSITIVE ANOMALIES HAVE NOT RECEDED TO A
LARGE DEGREE...IN FACT - MOST SITES ARE STILL AROUND OR JUST BELOW
ONE FT ABOVE AVG. THIS WILL KEEP AN ELEVATED RISK OF NEAR-MINOR
THRESHOLDS HEADING INTO THE NEXT HIGH TIDE CYCLE. NO SINGLE FORECAST
POINT HAS CRITERIA BEING REACHED...THOUGH MOST ARE FAIRLY CLOSE.
WILL CONTINUE TO MONITOR THESE TRENDS BUT LEVELS SHOULD CONTINUE TO
DROP ALBEIT SLOWLY - FROM CONTINUED W-NWLY WINDS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST FRIDAY FOR ANZ530-
531-535-536-538-539.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST
FRIDAY FOR ANZ532>534-537-540>543.
&&
$$
SYNOPSIS...BAJ
NEAR TERM...GMS
SHORT TERM...BJL
LONG TERM...BAJ
AVIATION...BJL/GMS
MARINE...BJL/GMS
TIDES/COASTAL FLOODING...GMS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1240 AM EST THU FEB 28 2013
.SYNOPSIS...
AN UPPER LEVEL LOW WILL MOVE ACROSS THE AREA OVERNIGHT AND PUSH
INTO THE NORTHEAST FOR THE END OF THE WEEK. AS THE LOW SHIFTS EAST
OF THE REGION...COLDER AIR WILL FILTER INTO THE AREA TONIGHT AND
AND PROVIDE SNOW SHOWERS INTO FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
UPDATE TO REDUCE POPS A BIT OVERNIGHT AS RADAR COVERAGE OF SNOW
SHOWERS HAS DIMINISHED. THE LATEST RAP MID-LEVEL ANALYSIS
INDICATES A RATHER ELONGATED CLOSED UPPER LOW THAT STRETCHES
ACROSS THE SOUTHERN GREAT LAKES AND OHIO VALLEY. AT THE
SURFACE...A 999MB LOW IS CENTERED ACROSS SOUTHERN MICHIGAN WITH
ANOTHER LOW DEVELOPING AS IT MOVES NORTHWARD ACROSS NEW JERSEY.
THE LOW IN MICHIGAN IS DRIVING A SOUTHWESTERLY FLOW ACROSS THE
AREA TODAY. SOUNDINGS INDICATE A SFC-900MB MELTING LAYER STRONG
ENOUGH TO ALLOW FOR PRECIP SOUTH AND WEST OF PITTSBURGH TO BE ALL
RAIN. 1000-700MB 2840M THICKNESS LINE ALSO SEEMS TO COINCIDE
FAIRLY WELL WITH RAIN/SNOW LINE NORTHEAST OF PITTSBURGH.
THIS EVENING...THE BROAD UPPER LOW WILL SLOWLY MEANDER EASTWARD
ACROSS THE OHIO VALLEY...WITH THE NEXT VORT LOBE SWINGING AROUND
ITS BASE. WRF-ARW 1KM SIMULATED REFLECTIVITY DEPICTS MORE
CONVECTIVE SHOWERS EARLY THIS EVENING...SO HAVE GONE WITH
ISOLATED/SCATTERED INCREASING TO MORE NUMEROUS AS THE UPPER LOW
APPROACHES FROM THE WEST. DESPITE COLDER AIR ADVECTING IN WITH
THE COLD POOL ALOFT AND ASSOCIATED UPPER LOW...GFS/NAM SOUNDINGS
CONTINUE TO INDICATE PRECIPITATION WILL FALL INITIALLY AS RAIN
WITH A SUFFICIENT SFC-900MB MELTING LAYER REMAINING IN PLACE.
THUS...FORECAST BEINGS WITH MOSTLY RAIN...EXCEPT FOR SOME RAIN-SNOW
CLOSER TO 1000-700MB CRITICAL THICKNESS ACROSS THE NORTH AND WITH
THE LACK OF A PRONOUNCED MELTING LAYER ACROSS THE RIDGES.
OVERNIGHT...GFS/NAM AGREE THAT THE UPPER LOW WILL CROSS THE AREA AS
IT SHIFTS FROM WESTERN OHIO INTO WESTERN NY. WEAK CAA AND COOLING
SFC-900MB LAYER WILL ALLOW FOR ENTIRE COLUMN TO DROP BELOW
FREEZING AND PRECIPITATION TO CHANGE OVER TO ALL SNOW SHOWERS
TONIGHT. ACCUMULATIONS WILL BE AN INCH OR LESS FOR SOUTHWEST
PA...EASTERN OHIO...AND NORTHERN WV WITH 1 TO 2 INCHES POSSIBLE
TONIGHT ACROSS THE ALLEGHENY FRONT/LAUREL HIGHLANDS AND I-80
CORRIDOR. TEMPS TONIGHT ARE FAIRLY CLOSE TO A MAV/MET BLEND...WITH
LOWS RANGING FROM THE MID 20S ACROSS THE EASTERN RIDGES TO THE
LOWER 30S ELSEWHERE.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
A MODEL CONSENSUS INDICATES THAT THE UPPER LOW WILL SLOWLY MEANDER
EASTWARD INTO NEW ENGLAND THURSDAY AND FRIDAY...LEAVING THE UPPER
OHIO VALLEY IN A MOIST...NORTHWESTERLY FLOW OFF OF THE GREAT
LAKES.
THE LOW-LEVEL FLOW WILL BE CLOSE TO ZONAL MUCH OF THE DAY THURSDAY
AS A SERIES OF VORT LOBES ROTATES AROUND THE UPPER LOW AND INTO
THE AREA. WITH SFC TEMPS WARMING TO THE MID TO UPPER 30S ACROSS
THE LOWLANDS...ANTICIPATE LITTLE ACCUMULATION DURING DAYLIGHT
HOURS ACROSS THE LOWLANDS. WITH SOME UPSLOPING AND TEMPS IN THE
LOWER 30S...1 TO 2 INCHES WILL BE POSSIBLE ACROSS THE HIGHER
ELEVATIONS.
VORT ENERGY WILL SLIDE EAST OF THE UPPER OHIO VALLEY THURSDAY
NIGHT INTO FRIDAY. DURING THIS TIME...THE LOW-LEVEL FLOW WILL
VEER TO MORE NORTH-NORTHWESTERLY...ALLOWING FOR A MOISTURE FETCH
OFF OF LAKE HURON WITH MOISTURE LACKING FROM A PARTIALLY FROZEN
LAKE ERIE. ONE LIMITING FACTOR DESPITE THE NNWRLY FLOW WILL BE
THAT THE AIR MASS WILL NOT BE QUITE COLD ENOUGH TO SUPPORT LAKE
EFFECT. THUS...ANTICIPATE LITTLE MORE THAN SCATTERED SNOW SHOWERS
THROUGH THIS PERIOD WITH AROUND AN INCH FOR THE LOWLANDS AND AN
ADDITIONAL 1 TO 2 FOR THE RIDGES. TEMPS THROUGH THIS PERIOD WILL
BE AROUND 5 DEGREES BELOW NORMAL WITH THE NORTHERLY COMPONENT
CONTINUING TO PULL COOLER...CANADIAN AIR INTO THE AREA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
ECMWF AND GFS INDICATE CONTD MAINTENANCE OF THE ERN NORTH
AMERICAN TROF VIA SHRTWV ENERGY THRU THE LONG TERM PD. THE
EXTENDED FORECAST THUS CONTINUES TO FEATURE SUB AVERAGE TEMPS AND
NR CLIMO/CHC POPS UNTIL THE TROF AXIS SHIFT SUFFICIENTLY
EWD...PROBABLY BY SATURDAY.
SHRTWV RIDGE IN ADVN OF MIDWRN LOW IS CURRENTLY PROGGED TO
SUPPRESS PRECIP PROBABILITIES...UNTIL THE LOW INITIATES PCPN LTR
ON TUE. CONFIDENCE IN THAT PORTION OF THE FORECAST IS MINIMAL
GIVEN PROJECTIONS OF A CUTOFF SYSTEM WITH QUESTIONS OF MAGNITUDE
AND PLACEMENT OF THE LOW CENTERS.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
GENERAL MVFR CIG FORECAST THROUGH THE PERIOD. PERIODS OF IFR CIGS
ARE POSSIBLE...PARTICULARLY DURING MORE PROBABLE TIMES OF -SN.
FOLLOWING TWO SHORTWAVES WHICH WILL BRING A HIGHER RISK OF SNOW
SHOWER ACTIVITY AND POSSIBLY LOWER CLOUDS. FIRST WILL MOVE ACROSS
OHIO DURING THE PREDAWN HOURS...THE SECOND WILL MOVE SOUTHWARD
THROUGH THE ENTIRE REGION THIS AFTERNOON. THE SECOND WAVE WILL BE
PUSHING A SFC FRONT SOUTHWARD. THE AFTERNOON WAVE WILL BRING A
HIGHER PROBABILITY OF WIDESPREAD SNOW SHOWERS AND THUS LOWER
RESTRICTIONS.
SOUTHWEST WINDS THIS MORNING WILL VEER TO WEST THIS AFTERNOON.
SPEEDS WILL GENERALLY BE BETWEEN 10 AND 15KTS.
.OUTLOOK.../THURSDAY NIGHT THROUGH MONDAY/...
MAINLY CIGS RESTRICTIONS ARE LIKELY INTO SUNDAY AS LOW PRES CONTINUES
TO DRIFT EWD. VFR CONDS EXPD TO RETURN MON AS HI PRES BLDS IN.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
215 AM EST THU FEB 28 2013
.UPDATE...
ISSUED AT 714 PM EST WED FEB 27 2013
DECIDED TO GO WITH AN ADVISORY FOR MARQUETTE COUNTY. LOOKING AT
PRESENT RADAR TRENDS...MORE ENHANCEMENT IS OCCURRING TO THE EAST OF
THE AREA AND IS HEADED THIS WAY. INTENSITY OF THE SNOW WITH UPSLOPE
FLOW HAS INCREASED ACROSS MARQUETTE COUNTY AS WELL AND HAD A REPORT
EARLIER AT 630 OF 3 INCHES OF SNOW IN HARVEY. NOT OUT OF THE
QUESTION THAT SOME AREAS COULD SEE 5 INCHES OF SNOW BEFORE THIS IS
ALL OVER. SYSTEM MOISTURE WILL PULL OUT AFTER MIDNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 426 PM EST WED FEB 27 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A BROAD MID LEVEL LOW
CIRCULATION OVER THE GREAT LAKES/OHIO VALLEY. AT THE SFC...A
WEAKENING LOW PRES CENTER WAS LOCATED NEAR FLINT. SYSTEM ENDED UP
SLIGHTLY FARTHER N THAN EXPECTED YESTERDAY...AND THUS THE ASSOCIATED
WEAKENING SNOW SHIELD WAS ABLE TO SPREAD FARTHER N AND W INTO UPPER
MI TODAY...AIDED BY A SHORTWAVE THAT PIVOTED AROUND THE LARGE MID
LEVEL LOW CIRCULATION. THE NW EDGE OF THE -SN HAS SPREAD TO ABOUT A
BIG BAY/CHAMPION/CRYSTAL FALLS LINE. SNOW ACCUMULATIONS HAVE
GENERALLY BEEN 1 INCH OR LESS THOUGH SOME 2-3 INCH AMOUNTS WERE
OBSERVED ACROSS MENOMINEE/DELTA/SRN SCHOOLCRAFT COUNTIES. SINCE THE
WEAKENING SHORTWAVE AND ASSOCIATED DEEP LAYER FORCING ASSOCIATED
WITH THE HEAVIER SNOW HAS ROTATED TO THE SW...-SN HAS BEEN
DIMINISHING IN AREAL COVERAGE FROM LATE MORNING THRU THE AFTN. AS
EXPECTED...THERE HAS NOT BEEN ANY EVIDENCE OF LES TODAY DESPITE
CYCLONIC NE FLOW AS AIR MASS HAS BEEN TOO WARM. IN FACT...ON VIS
SATELLITE IMAGERY...HIGH CLOUDS ARE AT TIMES THIN ENOUGH TO REVEAL
LITTLE IF ANY LAKE EFFECT CLOUDS OVER LAKE SUPERIOR. THE SNOW THAT
HAS RECENTLY INCREASED INTO NCNTRL UPPER MI APPEARS MOSTLY RELATED
TO A LONG ARC OF ISENTROPIC ASCENT EXTENDING W FROM NEW ENGLAND...
BUT IT CERTAINLY LOOKS LIKE THERE MAY NOW BE A LAKE COMPONENT TO
THIS HEAVIER SNOW THAT HAS DEVELOPED.
IN THE SHORT TERM...FOCUS SHIFTS FROM REMNANT -SN ASSOCIATED WITH
SLOWLY DEPARTING GREAT LAKES/OHIO VALLEY MID LEVEL LOW TO POTENTIAL
OF LES OFF LAKE SUPERIOR. WITH NO ADDITIONAL SHORTWAVES EVIDENT
PIVOTING TOWARD UPPER MI AND WITH MODELS INDICATING INCREASING DEEP
LAYER QVECTOR CONVERGENCE WITH TIME...EXPECT LINGERING AREAS OF -SN
OVER ROUGHLY THE E HALF OF UPPER MI TO CONTINUE TO DIMINISH TONIGHT.
ANY ADDITIONAL SNOW ACCUMULATION WILL BE LESS THAN 1 INCH.
ATTENTION THEN TURNS TO POTENTIAL LES OFF LAKE SUPERIOR. HIGHER RES
MODEL GUIDANCE CONTINUES TO POINT TOWARD LES/UPSLOPE ENHANCED SNOW
TONIGHT. ALTHOUGH DEEPER MOISTURE/SATURATION AND SYNOPTIC -SN IS
SPREADING OUT OVER ERN LAKE SUPERIOR...HAVE DOUBTS ON THE INSISTENCE
OF HIGH RES GUIDANCE TO OUTPUT IN WHAT SOME CASES ARE SIGNIFICANT
PCPN TOTALS TONIGHT (REGIONAL GEM SHOWS AROUND 0.5 INCHES OF PCPN
TONIGHT OVER THE HIGHER TERRAIN OF MARQUETTE COUNTY...LOCAL HIGH
RESWRF 0.3-0.4...06Z NAM SHOWED UPWARDS OF 1 INCH BUT 12Z NAM AT
LEAST TRENDED DOWN TO WHAT SHOULD BE A MORE REASONABLE 0.2-0.3).
850MB TEMPS OF ONLY -6 TO -9C ACROSS LAKE SUPERIOR WILL NOT BE
SUFFICIENT FOR LES. SO...ONCE THE ISENTROPIC ASCENT CURRENTLY AIDING
THE SNOW INTO NCNTRL UPPER MI FALLS APART TONIGHT...EXPECT THE SNOW
TO DIMINISH SIGNIFICANTLY. WILL THUS CARRY HIGH POPS INTO NCNTRL
UPPER MI THIS EVENING...THEN DIMINISH PCPN TO JUST SCT -SHSN
OVERNIGHT. EXPECT A FEW INCHES OF SNOW ACCUMULATION THRU THE EVENING
ACROSS THE HIGHER TERRAIN OF THE NCNTRL (MARQUETTE COUNTY IN
PARTICULAR). IF THE ONGOING SNOW SHOWS SIGNS OF PERSISTENCE AND
LITTLE MOVEMENT (HEAVIEST SNOW IS CURRENTLY OCCURRING FROM
MARQUETTE/HARVEY WSW TO ISHPEMING/GWINN) WILL LIKELY NEED TO HOIST
AN ADVY. FARTHER W...LACKING SYNOPTIC FORCING...NOTHING MORE THAN
DEVELOPING CHC POPS/SCT -SHSN APPEAR REASONABLE.
850MB TEMPS FALL ANOTHER DEGREE OR TWO THU...BUT EVEN THAT WILL
STILL NOT BE QUITE COLD ENOUGH FOR LES. WITH ANY DEEPER MOISTURE
EXITING AND SINCE THERE WILL PROBABLY BE SOME NEGATIVE IMPACT DUE TO
DAYTIME HEATING WITH HIGHER SUN ANGLE AT THIS TIME OF YEAR...SCT
-SHSN OFF THE LAKE SHOULD WIND DOWN DURING THE DAY.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 426 PM EST WED FEB 27 2013
PREFERRED THE 00Z/27 ECMWF AND GLOBAL GEM OVER THE 12Z/27 GFS FOR
THE ENTIRE LONG TERM SINCE THE GFS HAS DISPLAYED POOR RUN TO RUN
CONTINUITY AND LACKS AGREEMENT WITH OTHER MODELS.
KEPT DIMINISHING CHANCES OF LAKE EFFECT SNOW THU NIGHT INTO EARLY
FRI IN AREAS FAVORED BY NE LOW LEVEL WINDS...BUT PUSHED BACK WHEN
POPS GO AWAY ENTIRELY BY AROUND 3 HOURS TO 18Z FRI. AFTER
THAT...VERY DRY LOW LEVELS ASSOCIATED WITH A SFC AND 500MB RIDGE
PUSHING INTO THE CWA. LOW LEVEL FLOW WILL CONTINUE TO BE OUT OF THE
N/NE UNTIL THE SFC RIDGE AXIS COMPLETELY PASSES SUN NIGHT WITH
SLIGHTLY COLDER 850MB TEMPS...SO WILL KEEP INCREASED CLOUD COVER NEAR
LAKE SUPERIOR. MAY SEE A BRIEF RETURN OF NE FLOW LES LATE FRI NIGHT
WITH THE PASSAGE OF A 500MB TROUGH...BUT ANY ACCUMULATIONS WILL BE
MINOR.
THE STORY FOR SUN THROUGH NEXT WED IS THAT A 500MB LOW WILL MOVE
OVER THE CWA THROUGH TUE BEFORE MOVE S ON WED. AT THE SAME
TIME...INCREASINGLY STRONG SFC RIDGING WILL MOVE INTO THE CWA...SO
PRECIP WILL BE AT A MINIMUM. PRECIP...IF ANY...WILL BE MINOR SO
SLIGHT CHANCE POPS AT BEST SEEM APPROPRIATE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 215 AM EST THU FEB 28 2013
WIND DIRECTION IS MOST FAVORABLE FOR ENHANCED WINDS AT KSAW...AND
GUSTS THERE SHOULD BE IN THE 20-30KT RANGE THROUGHOUT THE FCST
PERIOD. AT KIWD...UPSLOPE N/NNE WINDS WILL LIKELY KEEP LOW MVFR CIGS
IN PLACE THRU THE FCST PERIOD. AS AIR MASS COOLS SLIGHTLY... LAKE
EFFECT -SHSN MAY GET UNDERWAY OVERNIGHT...BUT EXPECTATION IS FOR ANY
SHSN TO BE LIGHT AND NOT SIGNIFICANTLY REDUCE VIS. AT KCMX... MVFR
CIGS AT KCMX WILL CONTINUE. MAY SEE A FEW FLURRIES LATER TONIGHT AT
KCMX. AT KSAW...IDEAL UPSLOPE FLOW AND PERIODS OF -SN SHOULD RESULT
IN IFR CONDITIONS PREVAILING FOR THE NEXT SEVERAL HRS. SOME
IMPROVEMENT TO LOW MVFR SHOULD OCCUR BY MORNING WITH LOW MVFR
CONDITIONS CONTINUING THRU THE PERIOD UNDER UPSLOPE NORTHERLY FLOW.
WILL GO WITH PERSISTENCE FOR THIS FORECAST.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 426 PM EST WED FEB 27 2013
TIGHT PRES GRADIENT BTWN HIGH PRES TO THE N AND NW AND LOW PRES
TRACKING THRU THE LWR LAKES WILL RESULT IN NORTHEASTERLY WINDS OF
20-30KT ACROSS LAKE SUPERIOR THRU THU. GALE FORCE GUSTS SHOULD BE
FREQUENT ENOUGH TO MAINTAIN GALE WARNING FOR THE E HALF OF LAKE
SUPERIOR. IN ADVANCE OF HIGH PRES RIDGE BUILDING TOWARD THE AREA
FRI...TIGHT PRES GRADIENT WILL REMAIN...RESULTING IN CONTINUED
20-30KT NE WINDS. THE STRONG WINDS/HIGH WAVES AND INFLUX OF COLDER
AIR WILL RESULT IN FREEZING SPRAY DEVELOPING TONIGHT AND CONTINUING
THRU FRI NIGHT. HVY FREEZING SPRAY MAY OCCUR FOR A TIME THU
NIGHT/FRI MORNING. WINDS WILL THEN DIMINISH FROM W TO E FRI NIGHT AS
HIGH PRES RIDGE MOVES CLOSER. ON SAT...WINDS SHOULD BE BLO 20KT
ACROSS THE ENTIRE LAKE. LIGHT WINDS...MOSTLY 10KT OR LESS...ARE
EXPECTED SUN/MON AS SFC HIGH PRES RIDGE WILL EXTEND FROM HUDSON BAY
S ACROSS THE UPPER LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL 7 AM EST THIS MORNING FOR MIZ005.
LAKE SUPERIOR...
GALE WARNING UNTIL 10 AM EST THIS MORNING FOR LSZ244-245-248>250-
264>267.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...07
SHORT TERM...ROLFSON
LONG TERM...TITUS
AVIATION...07
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
253 PM CST THU FEB 28 2013
.DISCUSSION...
AN OVERALL BENIGN 7-DAY FORECAST PERIOD WITH THE EXCEPTION OF THE
MONDAY-TUESDAY TIME FRAME...IN WHICH AT LEAST PART OF THE FORECAST
AREA COULD GET CLIPPED WITH ACCUMULATING SNOWFALL.
IN THE MEANTIME...AFTERNOON WATER VAPOR IMAGERY ILLUSTRATES THE
TROUGH SPINNING OVER THE EASTERN CONUS...WHILE WEAK RIDGING IS IN
PLACE LOCALLY. LOW LEVEL MOISTURE TRAPPED BETWEEN SAID EASTERN
TROUGH AND AN AMPLIFYING WESTERN RIDGE HAS BEEN RESPONSIBLE FOR
PROLONGED LOW CLOUD COVER AND LITTLE VARIATION IN TEMPERATURES
OVER THE LAST SEVERAL DAYS. EXPECT THAT TO BE THE CASE AGAIN
TONIGHT...SO HAVE MAINTAINED A MOSTLY CLOUDY FORECAST FOR TONIGHT
AND LEANED TOWARD THE HIGHER END OF NUMERICAL GUIDANCE FOR LOW
TEMPS.
NORTHERLY FLOW REMAINS IN PLACE OVER THE FORECAST AREA THROUGH THE
WEEKEND AS THE WESTERN RIDGE BUILDS SLOWLY EASTWARD BUT IS SLOWED
BY THE BLOCKING HIGH OVER QUEBEC. HIGH TEMPERATURES FROM FRIDAY
THROUGHT THE WEEKEND WILL NOT STRAY FAR FROM THE 25 TO 35 DEGREE
RANGE /5 TO 10 DEGREES BELOW NORMAL/. THERE COULD BE A FEW
FLURRIES OR VERY LIGHT SNOW ON SATURDAY AND SATURDAY
NIGHT...MAINLY ACROSS CENTRAL MN...AS SHEARED MID LEVEL ENERGY
PASSES OVER. ACCOMPANYING MOISTURE IS NOT ABUNDANT...BUT LOOKS
SUFFICIENT TO WARRANT 20 POPS.
REGARDING THE MONDAY-TUESDAY SYSTEM...WHILE MODELS ARE STILL
FLUCTUATING FROM RUN TO RUN WITH THE TRACK...THE MN RIVER VALLEY
AND AREAS SOUTH STILL LOOK LIKE THE PRIME AREA TO SEE SNOWFALL
ACCUMULATIONS OF SEVERAL INCHES. HAVE MAINTAINED LIKELY POPS IN
FROM FAR WEST CENTRAL INTO SOUTH CENTRAL MN...WHERE IF THE 12Z ECMWF WERE
TO VERIFY...WARNING TYPE SNOWS WOULD BE SEEN.
IN THE AFTERMATH OF THE MONDAY SYSTEM...A HIGHLY AMPLIFIED RIDGE
IS FORECAST TO BUILD OVER THE CENTRAL CONUS...AS A TROUGH IS
CARVED OUT OVER THE WEST COAST. THIS WOULD TRANSLATE TO A WARMING
TREND OVER THE AREA...WITH HIGHS IN THE MID 30S TO MID 40S RANGE.
&&
.AVIATION.../18Z TAF ISSUANCE/
AREA REMAINS UNDER THE INFLUENCE OF BROAD CYCLONIC FLOW ASSOCIATED
WITH OCCLUDED LOW NOW OVER LAKE ONTARIO. EXPANSIVE MVFR CIGS IN
PLACE...AND EXPECT THEM TO REMAIN THERE THROUGH THE AFTERNOON.
CURRENTLY TRACKING A CLEARING IN THESE CIGS OVER THE ARROWHEAD
MOVING SOUTH AT ABOUT 20 KTS. ALL GUIDANCE SWEEPS THIS CLEARING
SOUTH ACROSS MN/WI THIS EVENING...WITH ALL TERMINALS EXPECTED TO
RETURN TO VFR THIS EVENING. SLOWED THE RETURN TO VFR SOME BASED ON
RAP HANDLING OF 925-850 RH...THOUGH THIS MAY BE A LITTLE SLOW.
ONLY CONCERN FOR NOT CLEARING OUT IS AT AXN...AS SFC RIDGE WILL BE
MOVING IN OVERNIGHT...WITH THE RAP INDICATING THAT THIS LOW LEVEL
MOISTURE STAYS TRAPPED UNDER AN INVERSION ASSOCIATED WITH THE
RIDGE. BY LATE FRIDAY MORNING...CU RULES FROM BOTH THE NAM/GFS
REMAIN NEGATIVE...AND DO ANTICIPATE AN MVFR CU FIELD TO DEVELOP BY
THE END OF THE TAF PERIOD.
KMSP...CIGS HAVE SETTLED IN AT 025 AND EXPECT THEM TO REMAIN THERE
UNTIL THEIR DEPARTURE. AS FOR THEIR DEPARTURE...THE NAM PUSHES THEM
OUT AROUND 4Z...WHILE THE RAP HOLDS ON TO THE LOW LEVEL MOISTURE
THROUGH 9Z. BY FRIDAY MORNING CONFIDENCE IS HIGH IN STARTING OUT
WITH VFR CONDS. WITH PLENTY OF LOW LEVEL MOISTURE HANGING
AROUND...EXPECT EXPANSIVE STRATOCU FIELD TO DEVELOP AS WE BEGIN TO
MIX TOMORROW MORNING...AS INDICATED BY THE NEGATIVE CU RULES. CIGS
WILL LIKELY START MVFR AND TREND TOWARD VFR LEVELS IN THE
AFTERNOON...BUT TO HARD TO PIN DOWN WHEN THAT MAY OCCUR AT THIS
POINT...SO KEPT THINGS SIMPLE TOWARD THE END OF THE TAF. NO OTHER
ISSUES ARE EXPECTED...WITH WINDS REMAINING IN THE 010-030 RANGE
FOR THE NEXT 30 HOURS.
/OUTLOOK FOR KMSP/
SAT...VFR. WINDS LGT AND VRB.
SUN...VFR. SE WINDS 5 KTS.
MON...CHANCE OF SN. VFR OUTSIDE OF SNOW...IFR OR LOWER WITH SN.
ESE WINDS 10-20 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
LS/MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1146 AM CST THU FEB 28 2013
.UPDATE...
18Z AVIATION DISCUSSION ADDED BELOW.
&&
.PREV DISCUSSION...
/ISSUED 558 AM CST THU FEB 28 2013/
SHORT TERM...TODAY THROUGH SATURDAY NIGHT.
AT 3 AM...THE LARGE OCCLUDED LOW WAS CENTERED OVER ABOUT LAKE
ONTARIO. THE SYSTEM IS CRAWLING EASTWARD AND CYCLONIC FLOW
EXTENDS ALL THE WAY TO THE DAKOTA STATE LINE. STRATUS ACROSS MUCH
OF THE MIDWEST WILL BE SLOW TO DISSIPATE AND MODELS SHOW STRONGLY
NEGATIVE CU RULE VALUES OVER WRN/SRN MN THIS AFTERNOON...SO ANTICIPATING
A RATHER CLOUDY DAY TODAY. TEMPERATURES ARE SEASONABLY MILD THIS
MORNING...RANGING FROM AROUND 20 WEST AND LOWER 30S ACROSS ERN MN
AND WRN WI. THE CLOUD COVER SHOULD LIMIT THE EXTENT OF WARMING. MID
40 DEGREE TEMPS ARE NOT EXPECTED ACROSS CNTRL MN...UNLIKE WHAT
TRANSPIRED YESTERDAY.
DRY WEATHER IS FORECAST TONIGHT THROUGH FRIDAY NIGHT WITH A
GRADUAL DECREASE IN CLOUD COVER AS THE LOW PULLS WAY AND RIDGING
BUILDS IN FROM THE NORTHERN PLAINS. COULD BE A COLD NIGHT TONIGHT
WITH LOWS IN THE SINGLE DIGITS IN SPOTS AS THAT RIDGING BUILDS
EASTWARD...BUT THE THREAT FOR LINGERING CLOUD COVER MAY KEEP
THINGS MILDER...EVEN MORE SO THAN THE CURRENT FORECAST. CLOUDS
WILL CLEAR BY FRIDAY NIGHT AS THE RIDGE AXIS PUSHES OVERHEAD WHICH
SHOULD ALLOW FOR SINGLE DIGIT LOWS IN MANY LOCATIONS.
THE RIDGE WILL PUSH EAST SATURDAY AS BUILDING THICKNESSES AND WAA
ENGULFS THE PLAINS. THIS WILL BRING A WARM FRONT EASTWARD THROUGH
MN AND WRN WI. SHEARED 500MB VORTICITY MAY BE ENOUGH TO GENERATE A
BAND OF LIGHT SNOW WITH THE FRONT...BUT DRY AIR IN THE BOUNDARY
LAYER SHOULD GOBBLE UP MUCH THAT FALLS FROM THE MID LEVELS.
STILL...SLGT CHC POPS ARE JUSTIFIED.
LONG TERM...SUNDAY THROUGH WEDNESDAY.
A LARGE...WARM RIDGE OVER THE ROCKIES AND WESTERN PLAINS WILL
BECOME SQUASHED AS A POTENT TROUGH DIGS INTO THE PACIFIC NORTHWEST
FROM THE GULF OF ALASKA SUNDAY. MEANWHILE...THE EASTERN TROUGH
WILL LIFT OUT...RESULTING IN A MUCH LESS AMPLIFIED/SPLIT FLOW
PATTERN ACROSS THE CONUS AS THE NWRN U.S. ENERGY PUSHES INTO THE
CENTRAL OR NORTHERN PLAINS SUNDAY NIGHT. THIS SCENARIO IS
WREAKING HAVOC ON MODEL CONSISTENCY. THERE ARE TWO POSSIBLE
SOLUTIONS. ONE...AS THE SPLIT FLOW IN THE UPPER LEVELS TAKES
SHAPE...THE INITIAL CONSOLIDATED ENERGY BREAKS UP AND LEAVES TWO
WEAKENING SURFACE SYSTEMS WELL SOUTH OF MN/WI...AND LITTLE...IF
ANY ACCUMULATING SNOW IN THE CWA. TWO...THE UPPER LEVELS REMAIN
PHASED A BIT LONGER AND RESULTS IN A MORE DEVELOPED...POTENT
SYSTEM THAT TRACKS FURTHER NORTH ACROSS IOWA. THE LATTER SOLUTION
COULD BRING SEVERAL INCHES OF ACCUMULATION TO MUCH OF THE CWA LATE
SUNDAY NIGHT INTO MONDAY NIGHT.
MODELS MADE A SIGNIFICANT JUMP NORTHWARD WITH IT YESTERDAY...
FAVORING THE MORE PHASED SOLUTION. THIS MORNING HOWEVER...THE FIM
AND ECMWF REVERTED BACK TO THE SOUTH AND ONLY CLIP SWRN MN WITH
ACCUMULATING SNOW. THE GEM...GFS...GEFS...AND UKMET ARE MUCH
FURTHER NORTH. THE GEM SEEMS TO HAVE GONE OVERBOARD WITH INTENSITY
AND DURATION OF SNOW THOUGH...GIVING MUCH OF THE MIDWEST MORE
THAN 8 INCHES. THE FORECAST FAVORED A COMPROMISE BETWEEN THE TWO
EXTREMES AND CLOSELY RESEMBLES THE GFS/GEFS WHICH IS A NICE BLEND
OF THE GEM AND ECMWF/FIM.
THAT BEING SAID...DID NOT MAKE TOO MANY CHANGES IN THE SUNDAY
NIGHT/MONDAY TIMEFRAME UNTIL CONFIDENCE INCREASES. KEPT LIKELY
POPS ACROSS SRN MN AND TAPERED THEM OFF TO CHC ACROSS NWRN WI. IT
WILL PROBABLY BE ANOTHER COUPLE DAYS BEFORE WE HAVE A GOOD HANDLE
ON IMPACTS WITH THIS SYSTEM...BUT AT THIS POINT SRN MN STANDS THE
BEST CHANCE AT SEVERAL INCHES OF SNOW.
&&
.AVIATION.../18Z TAF ISSUANCE/
AREA REMAINS UNDER THE INFLUENCE OF BROAD CYCLONIC FLOW ASSOCIATED
WITH OCCLUDED LOW NOW OVER LAKE ONTARIO. EXPANSIVE MVFR CIGS IN
PLACE...AND EXPECT THEM TO REMAIN THERE THROUGH THE AFTERNOON.
CURRENTLY TRACKING A CLEARING IN THESE CIGS OVER THE ARROWHEAD
MOVING SOUTH AT ABOUT 20 KTS. ALL GUIDANCE SWEEPS THIS CLEARING
SOUTH ACROSS MN/WI THIS EVENING...WITH ALL TERMINALS EXPECTED TO
RETURN TO VFR THIS EVENING. SLOWED THE RETURN TO VFR SOME BASED ON
RAP HANDLING OF 925-850 RH...THOUGH THIS MAY BE A LITTLE SLOW.
ONLY CONCERN FOR NOT CLEARING OUT IS AT AXN...AS SFC RIDGE WILL BE
MOVING IN OVERNIGHT...WITH THE RAP INDICATING THAT THIS LOW LEVEL
MOISTURE STAYS TRAPPED UNDER AN INVERSION ASSOCIATED WITH THE
RIDGE. BY LATE FRIDAY MORNING...CU RULES FROM BOTH THE NAM/GFS
REMAIN NEGATIVE...AND DO ANTICIPATE AN MVFR CU FIELD TO DEVELOP BY
THE END OF THE TAF PERIOD.
KMSP...CIGS HAVE SETTLED IN AT 025 AND EXPECT THEM TO REMAIN THERE
UNTIL THEIR DEPARTURE. AS FOR THEIR DEPARTURE...THE NAM PUSHES THEM
OUT AROUND 4Z...WHILE THE RAP HOLDS ON TO THE LOW LEVEL MOISTURE
THROUGH 9Z. BY FRIDAY MORNING CONFIDENCE IS HIGH IN STARTING OUT
WITH VFR CONDS. WITH PLENTY OF LOW LEVEL MOISTURE HANGING
AROUND...EXPECT EXPANSIVE STRATOCU FIELD TO DEVELOP AS WE BEGIN TO
MIX TOMORROW MORNING...AS INDICATED BY THE NEGATIVE CU RULES. CIGS
WILL LIKELY START MVFR AND TREND TOWARD VFR LEVELS IN THE
AFTERNOON...BUT TO HARD TO PIN DOWN WHEN THAT MAY OCCUR AT THIS
POINT...SO KEPT THINGS SIMPLE TOWARD THE END OF THE TAF. NO OTHER
ISSUES ARE EXPECTED...WITH WINDS REMAINING IN THE 010-030 RANGE
FOR THE NEXT 30 HOURS.
/OUTLOOK FOR KMSP/
SAT...VFR. WINDS LGT AND VRB.
SUN...VFR. SE WINDS 5 KTS.
MON...CHANCE OF SN. VFR OUTSIDE OF SNOW...IFR OR LOWER WITH SN.
ESE WINDS 10-20 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
BORGHOFF/MPG
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1120 AM CST THU FEB 28 2013
.AVIATION...18Z TAF ISSUANCE...
DRIER AIR IS MOVING IN FROM THE NORTH THIS MORNING AND WILL
EVENTUALLY SCATTER OUT MVFR CIGS FROM THE NORTH TO SOUTH THROUGH
THE AFTERNOON. NNE WINDS WILL CONTINUE TODAY AROUND 10 KT. SHOULD
SEE VFR CONDITIONS THROUGH THE EVENING AND TONIGHT. ADDITIONAL
MVFR CIGS ARE POSSIBLE BY FRI MORNING AT DLH AND HYR.
&&
.PREV DISCUSSION... /ISSUED 901 AM CST THU FEB 28 2013/
UPDATE...EXTENDED FLURRIES/SNOW SHOWERS ALONG SOUTH SHORE OF LAKE
SUPERIOR THROUGH 18Z AS RADAR INDICATES CONTINUED SNOW OFF LAKE.
THIS PRECIP SHOULD END AS DRIER AIR PUSHES IN FROM NORTH LATER
THIS MORNING. REST OF FCST UNCHANGED.
PREV DISCUSSION... /ISSUED 554 AM CST THU FEB 28 2013/
AVIATION...12Z TAFS
MVFR CEILINGS COVERED THE NORTHLAND THIS MORNING...AND WILL SLOWLY
ERODE FROM THE NORTH TODAY. WE DELAYED THE CLEARING...AS SATELLITE
AND THE LATEST RAP BOTH SUGGEST CLEARING WILL TAKE LONGER. THERE
MAY BE SOME LIGHT SNOW OR FLURRIES IN SPOTS AS WELL...MAINLY OVER
NORTHWEST WISCONSIN.
PREV DISCUSSION... /ISSUED 240 AM CST THU FEB 28 2013/
SHORT TERM...THE FA IS BETWEEN SYSTEMS FOR ANOTHER DAY WITH THE
LARGE HIGH OVER CANADA AND THE AREA OF LOW PRESSURE OVER THE
EASTERN GREAT LAKES. A TIGHT PRESSURE GRADIENT OVER THE EASTERN
HALF OF THE FA IS CREATING GUSTY NE WINDS. MEANWHILE...A SFC TROF
WAS LOCATED JUST TO THE W OF THE FA IN NW MN AT 07Z. THE TROF IS
EXPECTED TO WASH OUT TODAY WHILE A SFC RIDGE AXIS IS FORECAST TO
BEGIN AFFECTING THE NORTHERN TIER OF THE FA. AMONGST THESE
FEATURES ARE EMBEDDED PIECES OF SHORT WAVE ENERGY ROTATING FROM E
TO W THROUGH THE FA WHILE AN UPPER LEVEL TROF CURRENTLY IN THE
DAKOTAS MOVES EWD. WILL SEE SOME FLURRIES THIS MORNING OVER NW WI
IN RESPONSE TO THE EMBEDDED ENERGY. SOME LAKE ENHANCED SNOW
SHOWERS MAY AFFECT THE SOUTH SHORE THIS MORNING WITH THE NE FLOW
OVER THE LAKE AND WEAK CAA. THE SNOW SHOWERS SHOULD DISSIPATE
AROUND NOON WHEN DRIER AIR AND LOW LEVEL WAA IN THE 1000-850MB
LAYER OVERTAKE THE LES MECHANISMS.
THE RIDGING BUILDS OVER THE REST OF THE FA TODAY AND PERSISTS
THROUGH FRIDAY. EVEN THOUGH A WEAK UPPER TROF MOVES ACROSS THE FA
FRIDAY...THE ATMOSPHERE IS VERY DRY AND NO PCPN IS EXPECTED.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY.
A RIDGE OF HIGH PRESSURE WILL EXTEND SOUTH OVER THE NORTHLAND FROM
HIGH PRESSURE OVER HUDSON BAY FRIDAY NIGHT...SHIFTING EAST SATURDAY.
A SHORTWAVE ALOFT WILL MOVE THROUGH THE AREA DURING THE SAME
PERIOD...AND BRING A CHANCE FOR SOME LIGHT SNOW SATURDAY INTO
SATURDAY NIGHT. ANY ACCUMULATION LOOKS TO BE QUITE LIGHT AT THIS
TIME. THE LOW LEVEL FLOW WILL BE NORTH TO NORTHEAST FRIDAY
NIGHT/SATURDAY WITH 850MB TEMPS AROUND -10C TO -12C. THIS WOULD
SUPPORT SOME LES...HOWEVER...AIRMASS IS EXPECTED TO BE VERY DRY AND
WE DID NOT BRING IN ANY LES FRIDAY NIGHT/SATURDAY AT THIS TIME.
THE LOW LEVEL FLOW WILL BE EAST/NORTHEAST SUNDAY INTO MONDAY...WITH
850MB TEMPS AROUND -12C. WE AGAIN DID NOT ADD/INCREASE POPS FOR LES
AT THIS TIME AS THE AIR MASS REMAINS QUITE DRY. HOWEVER...A STRONGER
WAVE AND LOW PRESSURE SYSTEM MAY BRING SOME LIGHT SNOW MONDAY INTO
TUESDAY. AT THIS TIME...BOTH THE GFS AND ECMWF TAKE THE LOW WELL TO
OUR SOUTH...SO THE SIGNIFICANT PRECIP WILL OCCUR WELL SOUTH OF OUR
CWA. ADDED MOISTURE FROM THIS SYSTEM COULD ENHANCE SOME LES...MAINLY
ALONG THE SOUTH SHORE MONDAY NIGHT/TUESDAY...AND WE MAY HAVE TO
INCREASE SNOW CHANCES WITH LATER FORECASTS.
AN UPPER RIDGE WILL BUILD OVER THE REGION...WITH THE SURFACE RIDGE
RE-ESTABLISHING ITSELF MID WEEK...PROVIDING DRY CONDITIONS.
HIGHS THROUGH THE PERIOD WILL BE AROUND NORMAL...TO A FEW DEGREES
ABOVE AT TIMES. FRIDAY NIGHT LOOKS TO BE THE COLDEST
NIGHT...ESPECIALLY ACROSS FAR NORTHERN MINNESOTA WHERE TEMPS COULD
BE SEVERAL DEGREES BELOW ZERO.
&&
.POINT TEMPS/POPS...
DLH 27 13 24 5 / 10 0 0 10
INL 26 2 25 -5 / 10 0 0 0
BRD 29 13 29 5 / 10 0 0 0
HYR 29 12 28 1 / 10 0 0 10
ASX 27 15 25 9 / 20 0 0 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
AVIATION...TENTINGER
AREA FORECAST DISCUSSION
NWS DULUTH MN
901 AM CST THU FEB 28 2013
.UPDATE...EXTENDED FLURRIES/SNOW SHOWERS ALONG SOUTH SHORE OF LAKE
SUPERIOR THROUGH 18Z AS RADAR INDICATES CONTINUED SNOW OFF LAKE.
THIS PRECIP SHOULD END AS DRIER AIR PUSHES IN FROM NORTH LATER
THIS MORNING. REST OF FCST UNCHANGED.
&&
.PREV DISCUSSION... /ISSUED 554 AM CST THU FEB 28 2013/
AVIATION...12Z TAFS
MVFR CEILINGS COVERED THE NORTHLAND THIS MORNING...AND WILL SLOWLY
ERODE FROM THE NORTH TODAY. WE DELAYED THE CLEARING...AS SATELLITE
AND THE LATEST RAP BOTH SUGGEST CLEARING WILL TAKE LONGER. THERE
MAY BE SOME LIGHT SNOW OR FLURRIES IN SPOTS AS WELL...MAINLY OVER
NORTHWEST WISCONSIN.
PREV DISCUSSION... /ISSUED 240 AM CST THU FEB 28 2013/
SHORT TERM...THE FA IS BETWEEN SYSTEMS FOR ANOTHER DAY WITH THE
LARGE HIGH OVER CANADA AND THE AREA OF LOW PRESSURE OVER THE
EASTERN GREAT LAKES. A TIGHT PRESSURE GRADIENT OVER THE EASTERN
HALF OF THE FA IS CREATING GUSTY NE WINDS. MEANWHILE...A SFC TROF
WAS LOCATED JUST TO THE W OF THE FA IN NW MN AT 07Z. THE TROF IS
EXPECTED TO WASH OUT TODAY WHILE A SFC RIDGE AXIS IS FORECAST TO
BEGIN AFFECTING THE NORTHERN TIER OF THE FA. AMONGST THESE
FEATURES ARE EMBEDDED PIECES OF SHORT WAVE ENERGY ROTATING FROM E
TO W THROUGH THE FA WHILE AN UPPER LEVEL TROF CURRENTLY IN THE
DAKOTAS MOVES EWD. WILL SEE SOME FLURRIES THIS MORNING OVER NW WI
IN RESPONSE TO THE EMBEDDED ENERGY. SOME LAKE ENHANCED SNOW
SHOWERS MAY AFFECT THE SOUTH SHORE THIS MORNING WITH THE NE FLOW
OVER THE LAKE AND WEAK CAA. THE SNOW SHOWERS SHOULD DISSIPATE
AROUND NOON WHEN DRIER AIR AND LOW LEVEL WAA IN THE 1000-850MB
LAYER OVERTAKE THE LES MECHANISMS.
THE RIDGING BUILDS OVER THE REST OF THE FA TODAY AND PERSISTS
THROUGH FRIDAY. EVEN THOUGH A WEAK UPPER TROF MOVES ACROSS THE FA
FRIDAY...THE ATMOSPHERE IS VERY DRY AND NO PCPN IS EXPECTED.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY.
A RIDGE OF HIGH PRESSURE WILL EXTEND SOUTH OVER THE NORTHLAND FROM
HIGH PRESSURE OVER HUDSON BAY FRIDAY NIGHT...SHIFTING EAST SATURDAY.
A SHORTWAVE ALOFT WILL MOVE THROUGH THE AREA DURING THE SAME
PERIOD...AND BRING A CHANCE FOR SOME LIGHT SNOW SATURDAY INTO
SATURDAY NIGHT. ANY ACCUMULATION LOOKS TO BE QUITE LIGHT AT THIS
TIME. THE LOW LEVEL FLOW WILL BE NORTH TO NORTHEAST FRIDAY
NIGHT/SATURDAY WITH 850MB TEMPS AROUND -10C TO -12C. THIS WOULD
SUPPORT SOME LES...HOWEVER...AIRMASS IS EXPECTED TO BE VERY DRY AND
WE DID NOT BRING IN ANY LES FRIDAY NIGHT/SATURDAY AT THIS TIME.
THE LOW LEVEL FLOW WILL BE EAST/NORTHEAST SUNDAY INTO MONDAY...WITH
850MB TEMPS AROUND -12C. WE AGAIN DID NOT ADD/INCREASE POPS FOR LES
AT THIS TIME AS THE AIR MASS REMAINS QUITE DRY. HOWEVER...A STRONGER
WAVE AND LOW PRESSURE SYSTEM MAY BRING SOME LIGHT SNOW MONDAY INTO
TUESDAY. AT THIS TIME...BOTH THE GFS AND ECMWF TAKE THE LOW WELL TO
OUR SOUTH...SO THE SIGNIFICANT PRECIP WILL OCCUR WELL SOUTH OF OUR
CWA. ADDED MOISTURE FROM THIS SYSTEM COULD ENHANCE SOME LES...MAINLY
ALONG THE SOUTH SHORE MONDAY NIGHT/TUESDAY...AND WE MAY HAVE TO
INCREASE SNOW CHANCES WITH LATER FORECASTS.
AN UPPER RIDGE WILL BUILD OVER THE REGION...WITH THE SURFACE RIDGE
RE-ESTABLISHING ITSELF MID WEEK...PROVIDING DRY CONDITIONS.
HIGHS THROUGH THE PERIOD WILL BE AROUND NORMAL...TO A FEW DEGREES
ABOVE AT TIMES. FRIDAY NIGHT LOOKS TO BE THE COLDEST
NIGHT...ESPECIALLY ACROSS FAR NORTHERN MINNESOTA WHERE TEMPS COULD
BE SEVERAL DEGREES BELOW ZERO.
&&
.POINT TEMPS/POPS...
DLH 27 13 24 5 / 10 0 0 10
INL 26 2 25 -5 / 10 0 0 0
BRD 29 13 29 5 / 10 0 0 0
HYR 29 12 28 1 / 10 0 0 10
ASX 27 15 25 9 / 20 0 0 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...STEWART
LONG TERM....TENTINGER
AREA FORECAST DISCUSSION
NWS DULUTH MN
554 AM CST THU FEB 28 2013
.AVIATION...12Z TAFS
MVFR CEILINGS COVERED THE NORTHLAND THIS MORNING...AND WILL SLOWLY
ERODE FROM THE NORTH TODAY. WE DELAYED THE CLEARING...AS SATELLITE
AND THE LATEST RAP BOTH SUGGEST CLEARING WILL TAKE LONGER. THERE
MAY BE SOME LIGHT SNOW OR FLURRIES IN SPOTS AS WELL...MAINLY OVER
NORTHWEST WISCONSIN.
&&
.PREV DISCUSSION... /ISSUED 240 AM CST THU FEB 28 2013/
SHORT TERM...THE FA IS BETWEEN SYSTEMS FOR ANOTHER DAY WITH THE
LARGE HIGH OVER CANADA AND THE AREA OF LOW PRESSURE OVER THE
EASTERN GREAT LAKES. A TIGHT PRESSURE GRADIENT OVER THE EASTERN
HALF OF THE FA IS CREATING GUSTY NE WINDS. MEANWHILE...A SFC TROF
WAS LOCATED JUST TO THE W OF THE FA IN NW MN AT 07Z. THE TROF IS
EXPECTED TO WASH OUT TODAY WHILE A SFC RIDGE AXIS IS FORECAST TO
BEGIN AFFECTING THE NORTHERN TIER OF THE FA. AMONGST THESE
FEATURES ARE EMBEDDED PIECES OF SHORT WAVE ENERGY ROTATING FROM E
TO W THROUGH THE FA WHILE AN UPPER LEVEL TROF CURRENTLY IN THE
DAKOTAS MOVES EWD. WILL SEE SOME FLURRIES THIS MORNING OVER NW WI
IN RESPONSE TO THE EMBEDDED ENERGY. SOME LAKE ENHANCED SNOW
SHOWERS MAY AFFECT THE SOUTH SHORE THIS MORNING WITH THE NE FLOW
OVER THE LAKE AND WEAK CAA. THE SNOW SHOWERS SHOULD DISSIPATE
AROUND NOON WHEN DRIER AIR AND LOW LEVEL WAA IN THE 1000-850MB
LAYER OVERTAKE THE LES MECHANISMS.
THE RIDGING BUILDS OVER THE REST OF THE FA TODAY AND PERSISTS
THROUGH FRIDAY. EVEN THOUGH A WEAK UPPER TROF MOVES ACROSS THE FA
FRIDAY...THE ATMOSPHERE IS VERY DRY AND NO PCPN IS EXPECTED.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY.
A RIDGE OF HIGH PRESSURE WILL EXTEND SOUTH OVER THE NORTHLAND FROM
HIGH PRESSURE OVER HUDSON BAY FRIDAY NIGHT...SHIFTING EAST SATURDAY.
A SHORTWAVE ALOFT WILL MOVE THROUGH THE AREA DURING THE SAME
PERIOD...AND BRING A CHANCE FOR SOME LIGHT SNOW SATURDAY INTO
SATURDAY NIGHT. ANY ACCUMULATION LOOKS TO BE QUITE LIGHT AT THIS
TIME. THE LOW LEVEL FLOW WILL BE NORTH TO NORTHEAST FRIDAY
NIGHT/SATURDAY WITH 850MB TEMPS AROUND -10C TO -12C. THIS WOULD
SUPPORT SOME LES...HOWEVER...AIRMASS IS EXPECTED TO BE VERY DRY AND
WE DID NOT BRING IN ANY LES FRIDAY NIGHT/SATURDAY AT THIS TIME.
THE LOW LEVEL FLOW WILL BE EAST/NORTHEAST SUNDAY INTO MONDAY...WITH
850MB TEMPS AROUND -12C. WE AGAIN DID NOT ADD/INCREASE POPS FOR LES
AT THIS TIME AS THE AIR MASS REMAINS QUITE DRY. HOWEVER...A STRONGER
WAVE AND LOW PRESSURE SYSTEM MAY BRING SOME LIGHT SNOW MONDAY INTO
TUESDAY. AT THIS TIME...BOTH THE GFS AND ECMWF TAKE THE LOW WELL TO
OUR SOUTH...SO THE SIGNIFICANT PRECIP WILL OCCUR WELL SOUTH OF OUR
CWA. ADDED MOISTURE FROM THIS SYSTEM COULD ENHANCE SOME LES...MAINLY
ALONG THE SOUTH SHORE MONDAY NIGHT/TUESDAY...AND WE MAY HAVE TO
INCREASE SNOW CHANCES WITH LATER FORECASTS.
AN UPPER RIDGE WILL BUILD OVER THE REGION...WITH THE SURFACE RIDGE
RE-ESTABLISHING ITSELF MID WEEK...PROVIDING DRY CONDITIONS.
HIGHS THROUGH THE PERIOD WILL BE AROUND NORMAL...TO A FEW DEGREES
ABOVE AT TIMES. FRIDAY NIGHT LOOKS TO BE THE COLDEST
NIGHT...ESPECIALLY ACROSS FAR NORTHERN MINNESOTA WHERE TEMPS COULD
BE SEVERAL DEGREES BELOW ZERO.
&&
.POINT TEMPS/POPS...
DLH 27 13 24 5 / 10 0 0 10
INL 26 2 25 -5 / 10 0 0 0
BRD 29 13 29 5 / 10 0 0 0
HYR 29 12 28 1 / 10 0 0 10
ASX 27 15 25 9 / 20 0 0 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...GSF
LONG TERM....MELDE
AVIATION...MELDE
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
928 PM CST FRI MAR 1 2013
.UPDATE...
ISSUED AT 928 PM CST FRI MAR 1 2013
SEEMINGLY NON-STOP...ALBEIT VERY LIGHT...SNOW CONTINUES TO FALL
OVER THE CWA THIS EVENING...WITH ANOTHER BAND OF 10-20DBZ ECHOES
NOW GROWING FROM THE UIN AREA SOUTH TO NEAR THE I-70 CORRIDOR.
A FEW SPOTS COULD STILL SEE A DUSTING OF SNOW BUT FOR MOST OF THE
AREA THINK THE SNOW WILL BE MORE ALONG THE LINE OF FLURRIES...AND
WILL CONTINUE THEM THROUGHOUT THE NIGHT.
OTHER QUESTION IS IF THERE WILL BE ANY CLEARING OVERNIGHT. IR SATELLITE
PICS INDICATE SOME HOLES HAVE FORMED IN THE CLOUDS OVER E MO...BUT
MORE SIGNIFICANT CLEARING AREA IS WORKING S FROM EASTERN
IOWA...AND 900MB RUC RH FORECASTS SEEM TO HAVE A GOOD HANDLE ON
THIS CLEARING LINE. WILL WORK THIS CLEARING..AND DROP MENTION OF
FLURRIES...INTO OUR FAR N COUNTIES INCLUDING UIN...DURING THE
PREDAWN HOURS. WILL ALSO LOWER TEMPS A FEW DEGREES IN THIS PART
OF THE CWA TO ACCOUNT FOR THIS LATE NIGHT CLEARING.
TRUETT
&&
.SHORT TERM...(THROUGH TONIGHT)
ISSUED AT 213 PM CST FRI MAR 1 2013
FOCUS THRU THE PERIOD WILL BE PRECIP CHANCES.
POPS FOR TONIGHT WILL BE A LAST MIN DECISION BASED ON LATEST RADAR
TRENDS. WITH LITTLE IN THE WAY OF FORCING OR SOMETHING TO TRACK FOR
THE SN TONIGHT...WILL BE DIFFICULT TO PIN DOWN EXACTLY WHAT AREAS
WILL SEE LIGHT SN VERSUS FLURRIES AND NOTHING AT ALL. LATEST MDL
GUIDANCE SUGGESTS BEST CHANCES WILL BE IN FAR SRN PORTIONS OF THE
CWA AND PERHAPS A CONTINUING BAND IN CNTL MO. ELSEWHERE...FLURRIES
MAY PERSIST THRU MUCH OF THE EVENING HOURS. CAN NOT COMPLETELY RULE
OUT FLURRIES CONTINUING AFTER MIDNIGHT...BUT SHUD BE CONFINED TO FAR
SRN PORTIONS OF THE CWA IF THEY OCCUR THAT LATE.
WHILE SOME MDL GUIDANCE SUGGESTS CLOUDS DISSIPATING LATE
TONIGHT...GIVEN EXTENSIVE CLOUD COVER UPSTREAM...BELIEVE THAT CLOUDS
WILL STRUGGLE TO DISSIPATE TONIGHT. HAVE THEREFORE CONTINUED A
PERSISTENCE FORECAST FOR TEMPS TONIGHT.
TILLY
&&
.LONG TERM...(SATURDAY THROUGH NEXT FRIDAY)
ISSUED AT 213 PM CST FRI MAR 1 2013
(SATURDAY THROUGH TUESDAY)
FOCUS EARLY IN THE PERIOD WILL BE TEMPS AS THE SFC RIDGE BUILDS
INTO THE REGION. MDLS ARE GENERALLY IN GOOD AGREEMENT THRU SUN.
AS DISCUSSED ABOVE...EXPECT CLOUD COVER TO LINGER THRU MUCH OF THE
DAY SAT. HAVE THEREFORE TRENDED CLOSE TO PERSISTENCE KEEPING TEMPS
AOB THE COLDEST MOS THRU SAT NIGHT. WITH ONE BATCH OF CLOUDS MOVING
OUT OF THE REGION JUST BEFORE CI ASSOCIATED WITH THE NEXT SYSTEM
MOVES IN...SHUD BE A BRIEF TIME WHERE MUCH OF THE AREA IS CLOUD
FREE. WITH THE SFC RIDGE SETTING OVER THE REGION...GOOD
RADIATIONAL COOLING SHUD OCCUR.
FOCUS QUICKLY TURNS TO THE NEXT APPROACHING SYSTEM. MDL
DIFFERENCES BECOME APPARENT STARTING SUN. THERE ARE TWO BASIC
SOLNS AMONG THE MDLS. THE GFS/ECMWF/GEM IN ONE CAMP WITH THE
NAM/DGEX/LOCAL WRF IN THE OTHER. THE SREF AND GEFS MEAN ALSO TREND
AWAY FROM THE NAM SOLN LATE IN THE PERIOD. HAVE THEREFORE TRENDED
TWD THE GFS/ECMWF/GEM SOLNS. THIS RESULTS IN A WETTER FORECAST
WITH SIMILAR THERMAL PROFILES. GIVEN MDL PERFORMANCE WITH THIS
SYSTEM OVER THE PAST FEW DAYS...STILL HAVE SOMEWHAT LOW CONFIDENCE
IN ANY ONE SOLN.
WHILE THE ECMWF/GEM/GFS ARE IN RELATIVELY GOOD AGREEMENT EARLY IN
THE PERIOD...DIFFERENCES BECOME GREATER BY TUES. THE GFS BECOMES A
FAST AND STRONG OUTLIER WITH THE UPPER LOW. THE GEFS MEAN ALSO
TRENDS SLOWER THAN THE OPERATIONAL SOLN. NOT COMPLETELY SURE WHAT
TO MAKE OF THE ECMWF SOLN WHICH HAS THE UPPER LOW SO FAR DETACHED
FROM THE SFC WAVE. WITH SUPPORT FROM THE GEM...HAVE INCREASED POPS
MON NIGHT AND TUES...BUT KEPT GENERAL RA/SN MIX WORDING FOR PRECIP
TYPE FOR NOW.
(WEDNESDAY THROUGH FRIDAY)
WITH LITTLE TO NO PRECIP ANTICIPATED DURING THIS PERIOD...FOCUS
WILL TURN TO TEMPS ONCE AGAIN.
WHAT DIFFERENCES THERE WERE...MDLS HAVE COME INTO A GENERAL
AGREEMENT THRU THIS PERIOD. WITH THE SFC RIDGE IN PLACE ON
WED...TRENDED TWD COOLER GUIDANCE. WITH THE SFC RIDGE MOVING OUT
OF THE AREA BY THURS AND RIDGING ALOFT...STARTED A QUICK WARMING
TREND THRU THE END OF THE PERIOD.
TILLY
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 532 PM CST FRI MAR 1 2013
FLURRIES OR LIGHT SNOW WILL TAPER OFF TONIGHT AS A PERSISTENT
UPPER LEVEL TROF FINALLY BEGINS SHIFTING AWAY FROM THE REGION.
MVFR CIGS WITH OCCASIONAL BREAKS ARE EXPECTED TO CONTINUE
OVERNIGHT AND BEGIN TO BREAK UP TOMORROW WITH THE ARRIVAL OF DRIER
AIR. NLY WINDS WILL GRADUALLY BACK AND BECOME NWLY LATE IN THE TAF
PD.
SPECIFICS FOR KSTL...FLURRIES OR LIGHT SNOW WILL TAPER OFF TONIGHT
HOWEVER MVFR CIGS WITH OCCASIONAL BREAKS ARE EXPECTED TO CONTINUE
OVERNIGHT UNTIL DRIER AIR ARRIVES TOMORROW. NLY WINDS WILL
GRADUALLY BACK AND BECOME NWLY TOMORROW AFTN.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
836 PM CST FRI MAR 1 2013
.UPDATE...ONLY NOTICEABLE CHANGE TO GRIDS SO FAR THIS EVENING WAS
A FAIRLY SHARP REDUCTION IN SKY COVER...ESPECIALLY THROUGH
MIDNIGHT. 11-3.9 MICRON SATELLITE IMAGERY REVEALS NEARLY CLOUD-
FREE SKIES OVER MOST OF THE CWA AT THIS HOUR...WITH A FAIRLY SOLID
LOW STRATUS DECK HOLDING JUST OFF TO OUR EAST...AND A FAIR AMOUNT OF
MID-HIGH LEVEL CLOUDS STILL FOCUSED OVER WESTERN
NEBRASKA...ALTHOUGH THESE WILL GRADUALLY BE INVADING THE CWA AS
THE NIGHT WEARS ON. THE JURY IS STILL OUT ON THE FINE DETAILS
REGARDING THE TIMING AND SEVERITY OF FOG TONIGHT...BUT DESPITE
MODELS SUCH AS THE 01Z RAP LARGELY DOWNPLAYING WIDESPREAD
VISIBILITY RESTRICTIONS...HAVE MADE NO CHANGES TO THE PREVIOUS
FORECAST AS THE SYNOPTIC SETUP OF CLEAR SKIES/LIGHT AND VARIABLE
BREEZES CERTAINLY IS SUPPORTIVE OF SOME DEGREE OF FOG. HAVE ALSO
MADE NO CHANGES TO LOW TEMPS...WITH MOST OF THE CWA STILL ON TRACK
TO BOTTOM OUT SOMEWHERE BETWEEN 13-19 DEGREES.
&&
.SHORT TERM...TONIGHT AND TOMORROW. MAIN FORECAST CONCERNS LIE
WITH FOG POTENTIAL TONIGHT AND TEMPERATURES TOMORROW.
SAW A FEW FLURRIES AFFECT PRIMARILY THE WRN AND ERN FRINGES OF THE
CWA EARLIER THIS MORNING...BUT THE AFTERNOON HAS BEEN QUIET. THE
LOW LEVEL STRATUS HAS REMAINED STUBBORN FOR MOST OF THE AREA...BUT
THERE ARE PEAKS OF SUN OUT THERE. AT THE SURFACE...A RIDGE OF HIGH
PRESSURE EXTENDS FROM CENTRAL CANADA DOWN TO THE SRN
PLAINS...KEEPING WINDS NORTH/NORTHWESTERLY...AND GUSTY AT
TIMES...ESP IN AREAS THAT HAVE BEEN ABLE TO SEE A BIT OF SUN.
LOOKING TO THIS EVENING/OVERNIGHT...DRY CONDITIONS WILL CONTINUE
WITH SHARP UPPER LEVEL NORTHWESTERLY FLOW IN PLACE. EXPECTING CLOUD
COVER TO BE VARIABLE...AND AM INSERTING A FOG MENTION INTO THE
FORECAST. MODELS ARE IN GOOD AGREEMENT SHOWING THE SFC RIDGE AXIS
SLIDING EAST INTO AND THROUGH THE CWA OVERNIGHT...DROPPING WINDS
DOWN TO LIGHT/VARIABLE. EXPECTING FOG TO DEVELOP LATE THIS EVENING
AS TEMPERATURES COOL AND WINDS FALL OFF...WHICH SHOULD LINGER INTO
THE MID MORNING HOURS ON SATURDAY. OVERNIGHT LOWS LOOKING TO FALL
INTO THE MID/UPPER TEENS.
INTO TOMORROW...DRY CONDITIONS CONTINUE...WITH MODELS IN GOOD
AGREEMENT SHOWING THE UPPER LEVEL RIDGE IN PLACE OVER THE ROCKIES
GRADUALLY SLIDING TO THE EAST. AS THE SFC RIDGE AXIS CONTINUES TO
SLIDE EAST...A TROUGH OF LOW PRESSURE DEVELOPS ALONG THE HIGH
PLAINS...BRINGING A MORE SOUTHWEST TO WESTERLY COMPONENT TO THE
WINDS...THOUGH WIND SPEEDS LOOK TO ONLY TOP OUT ARND 10 MPH.
WARMER AIR ALOFT STARTS TO BUILD IN FROM THE WEST...BUT MODEL
SOUNDINGS SHOWING THINGS NOT MIXING OVERLY WELL...SO IT WILL BE
TOUGH TO FULLY TAP INTO THAT WARMER AIR. AS A RESULT WAS HESITANT
TO RAISE FORECAST HIGHS...BUT IT SHOULD STILL BE WARMER THAN
TODAY...ESP IN THE WEST. CURRENT FORECAST CALLS FOR MID 30S IN THE
EAST TO THE LOWER/MID 40S IN THE WEST.
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY. BEGINNING SATURDAY
NIGHT...AN UPPER LEVEL RIDGE OF HIGH PRESSURE OVER THE ROCKIES
WILL BEGIN TO BREAK DOWN/SHIFT EAST AS AN UPSTREAM TROUGH
TRANSLATES SOUTHEAST FM BRITISH COLUMBIA. A MILD AIRMASS WILL
EXPAND EASTWARD ONTO THE CENTRAL PLAINS BY SUNDAY WITH H85 TEMPS
CLIMBING TO NEAR 10C. FORECAST SOUNDING HOWEVER INDICATE VERY
LITTLE MIXING...AND ALTHOUGH WE ARE LOOKING AT A WARMER DAY WITH
THE WARM AIRMASS IN PLACE AHEAD OF AN APPROACHING COLD
FRONT...WILL KEEP TEMPS IN THE UPPER 40S/MID 50S DUE TO LACK OF
GOOD MIXING. WILL NEED TO MONITOR OUR EASTERN ZONES FOR LINGERING
LOW CLOUD COVER AS WELL...MORE SO INDICATED BY GFS...AS LOW CLOUDS
WOULD IMPACT TEMPS.
SUNDAY NIGHT...THE UPPER TROUGH TRANSLATES INTO THE WESTERN
DAKOTAS WITH THE ASSOCIATED COLD FRONTAL BOUNDARY SWEEPING
SOUTHEAST OVERNIGHT. GOOD MID LEVEL FRONTOGENESIS IS PROGGED
BETWEEN H85 AND H7 AFTER 06Z...AND WOULD NOT BE SURPRISED TO SEE
SOME SPRINKLES/BRIEF SHOWER. FORECAST SOUNDINGS INDICATE DENDRITIC
MOISTURE IS LACKING...AND WITH TEMPS NEAR/BELOW FREEZING AM
HESITANT TO INCLUDE FREEZING PCPN POTENTIAL AND WILL LEAVE FCST
DRY FOR NOW AND MONITOR TRENDS GIVEN THIS LOOKS LIKE MAINLY TRACE
AMNTS OF PCPN. WINDS SHIFT NW FOLLOWING FROPA WITH 6HR PRESSURE
RISES PROGGED NEAR 8MB. WINDY CONDITIONS WILL DEVELOP MONDAY IN A
TIGHT PRESSURE GRADIENT AS THE LOW MOVES INTO SOUTHERN MN.
FORECAST SOUNDINGS ON MONDAY SUGGEST MIXING NEAR H8 WITH WINDS AT
THE TOP OF THE LAYER PROGGED AROUND 45KTS. MONDAY LOOKS TO FEATURE
WINDY/COOLER CONDITIONS AND WILL NEED TO WATCH FOR POTENTIAL WIND
ADV.
PCPN CHCS MONDAY/MONDAY NIGHT WILL BE DEPENDENT UPON THE TRACK OF
THE UPPER LOW CROSSING THE PLAINS WITH THE NAM/ECMWF/GFS
ENSEMBLE FAVORING A FARTHER NORTH TRACK THAN THE GFS/GEM. FCST IS
BASED ON THE FARTHER NORTH TRACK OF SYSTEM IN LINE WITH NAM/EC/GEM
WITH SLIGHT CHCS/BUFFER POPS IN OUR NORTHERN/EASTERN ZONES ON THE
BACK SIDE OF THE LOW...AND IF NORTHERN TREND CONTINUES...MAY NOT
NEED POPS AT ALL IN DRY SLOT.
TUESDAY SHLD BE THE COLDEST OF THE WORKWEEK IN THE COLD AIRMASS
BEHIND THE SYSTEM AS A 1035MB SURFACE HIGH BUILDS SOUTH ONTO THE
PLAINS. TEMPS BEGIN TO RECOVER ON WEDNESDAY AS SFC RIDGE AXIS
SHIFTS EAST AND HEIGHTS RISE BEHIND THE DEPARTING LOW. THE PATTERN
ALOFT TRANSITIONS SOUTHWESTERLY BY THE END OF THE WORKWEEK AHEAD
OF AN UPPER TROUGH DEEPENING ALONG THE WEST COAST/SOUTHWEST CONUS.
WARM FRONTAL BOUNDARY LIFTS NORTHWARD WITH TEMPS EXPECTED TO TOP
OUT WELL INTO THE 40S/50S FOR THE LATTER PART OF THE WORKWEEK.
&&
.AVIATION...00Z TAF. MAIN CONCERN FOR THE TAF PERIOD IS THE
POTENTIAL FOR REDUCED VSBYS IN FOG TONIGHT. SFC RIDGE AXIS IS
IN PLACE ACROSS CENTRAL AND EASTERN NEB THIS EVENING AND RIDGE
AXIS WILL GRADUALLY SHIFT EAST TONIGHT. SKIES HAVE CLEARED AND IN
GOOD RADIATIONAL CONDITIONS WITH LIGHT WINDS...FOG DEVELOPMENT IS
POSSIBLE WITH POTENTIAL FOR IFR/LIFR VSBYS/CIGS. HAVE TRENDED
VSBYS LOWER TONIGHT AND WILL MONITOR FOR LIFR CONDITIONS.
CONDITIONS ARE EXPECTED TO IMPROVE MID/LATE MORNING SATURDAY WITH
CIGS INCREASING TO VFR IN AFTN. WINDS WILL TRANSITION SOUTHERLY ON
BACK SIDE OF RIDGE.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...PFANNKUCH
SHORT TERM...ADO
LONG TERM/AVIATION...FAY
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
704 AM CST THU FEB 28 2013
.UPDATE...
ISSUED AT 653 AM CST THU FEB 28 2013
FORECAST REMAINS ON TRACK...NO CHANGES PLANNED AT THIS TIME.
WATCHING AN AREA OF STRATUS THAT HAS SLOWLY ADVANCED TOWARD KLBF.
NEAR TERM SOLUTIONS ARE SPLIT ON WHETHER THE STRATUS WILL CONTINUE
TO ADVANCE AND EVENTUALLY COVER THE SKIES ABOVE LBF. THE GUIDANCE
ALSO IS SPLIT ON THE EVENTUAL BREAKUP OF THE CLOUD DECK...WHICH
WOULD BE OF SIGNIFICANCE TO TEMPERATURES THIS MORNING AND
AFTERNOON. WILL MAINTAIN THE IDEA THAT THE STRATUS WILL REMAIN
GENERALLY EAST OF HIGHWAY 83 THROUGH MORNING...THEN BREAK INTO THE
AFTERNOON.
&&
.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 305 AM CST THU FEB 28 2013
THROUGH 12Z FRIDAY...BROAD AREA OF FRONTOGENESIS REMAINS FIXED
ACROSS NORTH CENTRAL NEBRASKA EARLY THIS MORNING WITH PROGRESSIVE
NORTHWESTERLY FLOW ALOFT USHERING IN A STEADY FEED OF MOISTURE.
STRATUS HAS BACKED WEST THIS MORNING...AS KTIF...KVTN AND POINTS
EAST ARE NOW REPORTING OVC012 OR LOWER. NEAR TERM SOLUTIONS SEEM TO
HAVE A GOOD HANDLE AT THIS POINT WITH THE STRATUS...HOWEVER THE 06Z
RAP RUN SEEMS TO BE A BIT TOO AMBITIOUS WITH THE WESTERN EXTENT OF
THE LOWER CEILINGS...WHEREAS THE 00Z NAM IS SLIGHTLY EAST. FELT THAT
A BLEND OF THE TWO BEST REPRESENTS THE CURRENT CONDITIONS...AND THUS
WILL EMPLOY THE BLEND THROUGH MIDDAY TODAY. WITH THIS
BLEND...STRATUS IS INDICATED TO REMAIN ACROSS MUCH OF NORTH CENTRAL
NEBRASKA AND THE EASTERN SANDHILLS FOR MUCH OF THE DAY. BECAUSE OF
THE CLOUD COVER...HIGH TEMPERATURES MAY ONCE AGAIN STRUGGLE TO REACH
0C EAST OF AN AINSWORTH TO BARTLETT LINE. WEST...ACROSS THE SAND
HILLS AND EASTERN PANHANDLE NEBRASKA...WAA IN THE LOW TO MID LEVELS
AND CLEARING SHOULD PROVIDE FOR TEMPERATURES ABOVE 40F.
FOR THIS EVENING AND OVERNIGHT...INHERITED FORECAST INDICATED THE
POTENTIAL OF --SN ACROSS NORTHERN PORTIONS OF THE CWA. THERE IS A
WEAK UPPER LEVEL SHORTWAVE PROGGED TO PASS THROUGH NORTHWESTERLY
FLOW THAT WILL INCREASE LIFT AND PROVIDE FOR A BRIEF PERIOD OF
SATURATION WITHIN THE DENDRITIC LAYER. LIFT IS WEAK WITH THIS
WAVE...AND DEEP MOISTURE IS LACKING...SO GOING WITH THE
LIGHT/NON-MEASURABLE PRECIPITATION SEEMS THE BEST WAY TO HANDLE THIS
AT THIS POINT IN TIME.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 305 AM CST THU FEB 28 2013
AN UPPER LEVEL DISTURBANCE WILL DIVE SOUTHEAST ACROSS THE AREA
FRIDAY MORNING. SOME VERY WEAK LIFT AND A RATHER MOIST DENDRITIC
LAYER COULD YIELD A FEW FLURRIES BEFORE NOON...OTHERWISE CLOUDS
SHOULD DECREASE DURING THE AFTERNOON AS THE SYSTEM CONTINUES MOVING
SOUTHEAST AWAY FROM THE AREA. AT THE SURFACE...A STATIONARY FRONT
WILL REMAIN ANCHORED FROM NORTH TO SOUTH ACROSS WESTERN NEBRASKA.
THIS FRONT WILL PUSH EAST INTO CENTRAL NEBRASKA SATURDAY...AND
EASTERN NEBRASKA BY SUNDAY. WESTERLY DOWNSLOPE WINDS TO THE WEST OF
THE FRONT WILL BRING 50 DEGREE HIGHS TO WESTERN NEBRASKA
SATURDAY...SPREADING INTO CENTRAL NEBRASKA BY SUNDAY. A 60 DEGREE
READING OR TWO CANNOT BE RULED OUT BY SUNDAY ACROSS FAR SOUTHWEST
NEBRASKA...AS SNOWPACK WILL BE DWINDLING BY THIS TIME.
MONDAY INTO TUESDAY STILL LOOKS INTERESTING. ALL MODELS DROP A
COMPACT CLOSED LOW SOUTHEAST ACROSS THE CENTRAL AND NORTHERN PLAINS.
MODELS HAVE BEEN STRUGGLING WITH THE TRACK OF THE SYSTEM...BUT THE
LATEST 00Z SUITE ARE ACTUALLY ALL FAIRLY CLOSE TOGETHER...AND TRACK
THE CENTER OF THE SYSTEM SOUTHEAST ACROSS NORTHERN NEBRASKA. THE
ECMWF IS FARTHEST SOUTH WITH A TRACK FROM CHADRON TO FALLS
CITY...AND THE GFS IS JUST NORTH OF THIS TRACK ALONG THE NEB/SD
BORDER. MOST OF THE PRECIPITATION WILL FALL TO THE NORTH OF THE
TRACK...SO THE ECMWF SOLUTION WOULD BRING THE HIGHEST POTENTIAL
FOR SOME ACCUMULATING SNOW TO NORTHERN NEBRASKA. ANOTHER THING TO
WATCH WITH THIS SYSTEM IS THE WIND POTENTIAL. THE GFS REALLY
CRANKS UP THE 850 MB WIND SPEEDS /NEAR 55 KTS/ ON THE BACKSIDE OF
THE LOW ACROSS WESTERN NEBRASKA...THE ECMWF IS LESS IMPRESSIVE.
BOTTOM LINE HERE IS THAT WE WILL CONTINUE TO MONITOR THE LATEST
TREND IN THE MODELS. A SHIFT FARTHER SOUTH WOULD MEAN LESS WIND
BUT MORE SNOWFALL POTENTIAL...AND A SHIFT NORTH WOULD MEAN VERY
LITTLE PRECIPITATION BUT MORE WIND.
BY MID WEEK A WARMING TREND WILL DEVELOP ONCE AGAIN AHEAD OF A
DEVELOPING LONG WAVE TROUGH ACROSS THE WESTERN CONUS. SOUTHERLY
WINDS WILL BEGIN TO TRANSPORT MOISTURE NORTHWARD BY WEEKS
END...POSSIBLE LEADING TO PRECIPITATION BY THE WEEKEND.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 537 AM CST THU FEB 28 2013
MVFR CEILINGS ARE FORECAST TO PERSIST AT KVTN UNTIL 18Z/28TH. WHILE
THERE COULD BE TIMES WHEN CEILINGS GO VFR...THE RAP MODEL SEEMS TO BE
HANDLING THE AREAS OF STRATUS BEST...KEEPING KVTN WITHIN THE LOWER
CEILINGS INTO EARLY AFTERNOON. KLBF IS EXPECTED TO CONTINUE TO
REMAIN IN VFR CONDITIONS THROUGH THE FORECAST PERIOD...HOWEVER THE
STRATUS IS JUST TO THE EAST OF THE TERMINAL...SO WILL NEED TO BE
WATCHED CLOSELY AS NEAR TERM SOLUTIONS ARE SPLIT ON WHETHER THE
LOWER CEILINGS MAKE IT AS FAR SOUTHWEST AS KLBF. SHORT-FUSED
AMENDMENTS MAY BE NEEDED AT KLBF AS FORECAST CONFIDENCE IS LOW TO
MEDIUM AT THIS TIME. OTHERWISE SURFACE WINDS SHOULD REMAIN LIGHT
AND FROM THE NORTHWEST AT OR BELOW 10KT FOR BOTH FORECAST SITES
THROUGH THE PERIOD.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JACOBS
SHORT TERM...JACOBS
LONG TERM...TAYLOR
AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
538 AM CST THU FEB 28 2013
.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 305 AM CST THU FEB 28 2013
THROUGH 12Z FRIDAY...BROAD AREA OF FRONTOGENESIS REMAINS FIXED
ACROSS NORTH CENTRAL NEBRASKA EARLY THIS MORNING WITH PROGRESSIVE
NORTHWESTERLY FLOW ALOFT USHERING IN A STEADY FEED OF MOISTURE.
STRATUS HAS BACKED WEST THIS MORNING...AS KTIF...KVTN AND POINTS
EAST ARE NOW REPORTING OVC012 OR LOWER. NEAR TERM SOLUTIONS SEEM TO
HAVE A GOOD HANDLE AT THIS POINT WITH THE STRATUS...HOWEVER THE 06Z
RAP RUN SEEMS TO BE A BIT TOO AMBITIOUS WITH THE WESTERN EXTENT OF
THE LOWER CEILINGS...WHEREAS THE 00Z NAM IS SLIGHTLY EAST. FELT THAT
A BLEND OF THE TWO BEST REPRESENTS THE CURRENT CONDITIONS...AND THUS
WILL EMPLOY THE BLEND THROUGH MIDDAY TODAY. WITH THIS
BLEND...STRATUS IS INDICATED TO REMAIN ACROSS MUCH OF NORTH CENTRAL
NEBRASKA AND THE EASTERN SANDHILLS FOR MUCH OF THE DAY. BECAUSE OF
THE CLOUD COVER...HIGH TEMPERATURES MAY ONCE AGAIN STRUGGLE TO REACH
0C EAST OF AN AINSWORTH TO BARTLETT LINE. WEST...ACROSS THE SAND
HILLS AND EASTERN PANHANDLE NEBRASKA...WAA IN THE LOW TO MID LEVELS
AND CLEARING SHOULD PROVIDE FOR TEMPERATURES ABOVE 40F.
FOR THIS EVENING AND OVERNIGHT...INHERITED FORECAST INDICATED THE
POTENTIAL OF --SN ACROSS NORTHERN PORTIONS OF THE CWA. THERE IS A
WEAK UPPER LEVEL SHORTWAVE PROGGED TO PASS THROUGH NORTHWESTERLY
FLOW THAT WILL INCREASE LIFT AND PROVIDE FOR A BRIEF PERIOD OF
SATURATION WITHIN THE DENDRITIC LAYER. LIFT IS WEAK WITH THIS
WAVE...AND DEEP MOISTURE IS LACKING...SO GOING WITH THE
LIGHT/NON-MEASURABLE PRECIPITATION SEEMS THE BEST WAY TO HANDLE THIS
AT THIS POINT IN TIME.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 305 AM CST THU FEB 28 2013
AN UPPER LEVEL DISTURBANCE WILL DIVE SOUTHEAST ACROSS THE AREA
FRIDAY MORNING. SOME VERY WEAK LIFT AND A RATHER MOIST DENDRITIC
LAYER COULD YIELD A FEW FLURRIES BEFORE NOON...OTHERWISE CLOUDS
SHOULD DECREASE DURING THE AFTERNOON AS THE SYSTEM CONTINUES MOVING
SOUTHEAST AWAY FROM THE AREA. AT THE SURFACE...A STATIONARY FRONT
WILL REMAIN ANCHORED FROM NORTH TO SOUTH ACROSS WESTERN NEBRASKA.
THIS FRONT WILL PUSH EAST INTO CENTRAL NEBRASKA SATURDAY...AND
EASTERN NEBRASKA BY SUNDAY. WESTERLY DOWNSLOPE WINDS TO THE WEST OF
THE FRONT WILL BRING 50 DEGREE HIGHS TO WESTERN NEBRASKA
SATURDAY...SPREADING INTO CENTRAL NEBRASKA BY SUNDAY. A 60 DEGREE
READING OR TWO CANNOT BE RULED OUT BY SUNDAY ACROSS FAR SOUTHWEST
NEBRASKA...AS SNOWPACK WILL BE DWINDLING BY THIS TIME.
MONDAY INTO TUESDAY STILL LOOKS INTERESTING. ALL MODELS DROP A
COMPACT CLOSED LOW SOUTHEAST ACROSS THE CENTRAL AND NORTHERN PLAINS.
MODELS HAVE BEEN STRUGGLING WITH THE TRACK OF THE SYSTEM...BUT THE
LATEST 00Z SUITE ARE ACTUALLY ALL FAIRLY CLOSE TOGETHER...AND TRACK
THE CENTER OF THE SYSTEM SOUTHEAST ACROSS NORTHERN NEBRASKA. THE
ECMWF IS FARTHEST SOUTH WITH A TRACK FROM CHADRON TO FALLS
CITY...AND THE GFS IS JUST NORTH OF THIS TRACK ALONG THE NEB/SD
BORDER. MOST OF THE PRECIPITATION WILL FALL TO THE NORTH OF THE
TRACK...SO THE ECMWF SOLUTION WOULD BRING THE HIGHEST POTENTIAL
FOR SOME ACCUMULATING SNOW TO NORTHERN NEBRASKA. ANOTHER THING TO
WATCH WITH THIS SYSTEM IS THE WIND POTENTIAL. THE GFS REALLY
CRANKS UP THE 850 MB WIND SPEEDS /NEAR 55 KTS/ ON THE BACKSIDE OF
THE LOW ACROSS WESTERN NEBRASKA...THE ECMWF IS LESS IMPRESSIVE.
BOTTOM LINE HERE IS THAT WE WILL CONTINUE TO MONITOR THE LATEST
TREND IN THE MODELS. A SHIFT FARTHER SOUTH WOULD MEAN LESS WIND
BUT MORE SNOWFALL POTENTIAL...AND A SHIFT NORTH WOULD MEAN VERY
LITTLE PRECIPITATION BUT MORE WIND.
BY MID WEEK A WARMING TREND WILL DEVELOP ONCE AGAIN AHEAD OF A
DEVELOPING LONG WAVE TROUGH ACROSS THE WESTERN CONUS. SOUTHERLY
WINDS WILL BEGIN TO TRANSPORT MOISTURE NORTHWARD BY WEEKS
END...POSSIBLE LEADING TO PRECIPITATION BY THE WEEKEND.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 537 AM CST THU FEB 28 2013
MVFR CEILINGS ARE FORECAST TO PERSIST AT KVTN UNTIL 18Z/28TH. WHILE
THERE COULD BE TIMES WHEN CEILINGS GO VFR...THE RAP MODEL SEEMS TO BE
HANDLING THE AREAS OF STRATUS BEST...KEEPING KVTN WITHIN THE LOWER
CEILINGS INTO EARLY AFTERNOON. KLBF IS EXPECTED TO CONTINUE TO
REMAIN IN VFR CONDITIONS THROUGH THE FORECAST PERIOD...HOWEVER THE
STRATUS IS JUST TO THE EAST OF THE TERMINAL...SO WILL NEED TO BE
WATCHED CLOSELY AS NEAR TERM SOLUTIONS ARE SPLIT ON WHETHER THE
LOWER CEILINGS MAKE IT AS FAR SOUTHWEST AS KLBF. SHORT-FUSED
AMENDMENTS MAY BE NEEDED AT KLBF AS FORECAST CONFIDENCE IS LOW TO
MEDIUM AT THIS TIME. OTHERWISE SURFACE WINDS SHOULD REMAIN LIGHT
AND FROM THE NORTHWEST AT OR BELOW 10KT FOR BOTH FORECAST SITES
THROUGH THE PERIOD.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JACOBS
LONG TERM...TAYLOR
AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
305 AM CST THU FEB 28 2013
.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 305 AM CST THU FEB 28 2013
THROUGH 12Z FRIDAY...BROAD AREA OF FRONTOGENESIS REMAINS FIXED
ACROSS NORTH CENTRAL NEBRASKA EARLY THIS MORNING WITH PROGRESSIVE
NORTHWESTERLY FLOW ALOFT USHERING IN A STEADY FEED OF MOISTURE.
STRATUS HAS BACKED WEST THIS MORNING...AS KTIF...KVTN AND POINTS
EAST ARE NOW REPORTING OVC012 OR LOWER. NEAR TERM SOLUTIONS SEEM TO
HAVE A GOOD HANDLE AT THIS POINT WITH THE STRATUS...HOWEVER THE 06Z
RAP RUN SEEMS TO BE A BIT TOO AMBITIOUS WITH THE WESTERN EXTENT OF
THE LOWER CEILINGS...WHEREAS THE 00Z NAM IS SLIGHTLY EAST. FELT THAT
A BLEND OF THE TWO BEST REPRESENTS THE CURRENT CONDITIONS...AND THUS
WILL EMPLOY THE BLEND THROUGH MIDDAY TODAY. WITH THIS
BLEND...STRATUS IS INDICATED TO REMAIN ACROSS MUCH OF NORTH CENTRAL
NEBRASKA AND THE EASTERN SANDHILLS FOR MUCH OF THE DAY. BECAUSE OF
THE CLOUD COVER...HIGH TEMPERATURES MAY ONCE AGAIN STRUGGLE TO REACH
0C EAST OF AN AINSWORTH TO BARTLETT LINE. WEST...ACROSS THE SAND
HILLS AND EASTERN PANHANDLE NEBRASKA...WAA IN THE LOW TO MID LEVELS
AND CLEARING SHOULD PROVIDE FOR TEMPERATURES ABOVE 40F.
FOR THIS EVENING AND OVERNIGHT...INHERITED FORECAST INDICATED THE
POTENTIAL OF --SN ACROSS NORTHERN PORTIONS OF THE CWA. THERE IS A
WEAK UPPER LEVEL SHORTWAVE PROGGED TO PASS THROUGH NORTHWESTERLY
FLOW THAT WILL INCREASE LIFT AND PROVIDE FOR A BRIEF PERIOD OF
SATURATION WITHIN THE DENDRITIC LAYER. LIFT IS WEAK WITH THIS
WAVE...AND DEEP MOISTURE IS LACKING...SO GOING WITH THE
LIGHT/NON-MEASURABLE PRECIPITATION SEEMS THE BEST WAY TO HANDLE THIS
AT THIS POINT IN TIME.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 305 AM CST THU FEB 28 2013
AN UPPER LEVEL DISTURBANCE WILL DIVE SOUTHEAST ACROSS THE AREA
FRIDAY MORNING. SOME VERY WEAK LIFT AND A RATHER MOIST DENDRITIC
LAYER COULD YIELD A FEW FLURRIES BEFORE NOON...OTHERWISE CLOUDS
SHOULD DECREASE DURING THE AFTERNOON AS THE SYSTEM CONTINUES MOVING
SOUTHEAST AWAY FROM THE AREA. AT THE SURFACE...A STATIONARY FRONT
WILL REMAIN ANCHORED FROM NORTH TO SOUTH ACROSS WESTERN NEBRASKA.
THIS FRONT WILL PUSH EAST INTO CENTRAL NEBRASKA SATURDAY...AND
EASTERN NEBRASKA BY SUNDAY. WESTERLY DOWNSLOPE WINDS TO THE WEST OF
THE FRONT WILL BRING 50 DEGREE HIGHS TO WESTERN NEBRASKA
SATURDAY...SPREADING INTO CENTRAL NEBRASKA BY SUNDAY. A 60 DEGREE
READING OR TWO CANNOT BE RULED OUT BY SUNDAY ACROSS FAR SOUTHWEST
NEBRASKA...AS SNOWPACK WILL BE DWINDLING BY THIS TIME.
MONDAY INTO TUESDAY STILL LOOKS INTERESTING. ALL MODELS DROP A
COMPACT CLOSED LOW SOUTHEAST ACROSS THE CENTRAL AND NORTHERN PLAINS.
MODELS HAVE BEEN STRUGGLING WITH THE TRACK OF THE SYSTEM...BUT THE
LATEST 00Z SUITE ARE ACTUALLY ALL FAIRLY CLOSE TOGETHER...AND TRACK
THE CENTER OF THE SYSTEM SOUTHEAST ACROSS NORTHERN NEBRASKA. THE
ECMWF IS FARTHEST SOUTH WITH A TRACK FROM CHADRON TO FALLS
CITY...AND THE GFS IS JUST NORTH OF THIS TRACK ALONG THE NEB/SD
BORDER. MOST OF THE PRECIPITATION WILL FALL TO THE NORTH OF THE
TRACK...SO THE ECMWF SOLUTION WOULD BRING THE HIGHEST POTENTIAL
FOR SOME ACCUMULATING SNOW TO NORTHERN NEBRASKA. ANOTHER THING TO
WATCH WITH THIS SYSTEM IS THE WIND POTENTIAL. THE GFS REALLY
CRANKS UP THE 850 MB WIND SPEEDS /NEAR 55 KTS/ ON THE BACKSIDE OF
THE LOW ACROSS WESTERN NEBRASKA...THE ECMWF IS LESS IMPRESSIVE.
BOTTOM LINE HERE IS THAT WE WILL CONTINUE TO MONITOR THE LATEST
TREND IN THE MODELS. A SHIFT FARTHER SOUTH WOULD MEAN LESS WIND
BUT MORE SNOWFALL POTENTIAL...AND A SHIFT NORTH WOULD MEAN VERY
LITTLE PRECIPITATION BUT MORE WIND.
BY MID WEEK A WARMING TREND WILL DEVELOP ONCE AGAIN AHEAD OF A
DEVELOPING LONG WAVE TROUGH ACROSS THE WESTERN CONUS. SOUTHERLY
WINDS WILL BEGIN TO TRANSPORT MOISTURE NORTHWARD BY WEEKS
END...POSSIBLE LEADING TO PRECIPITATION BY THE WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 305 AM CST CST THU FEB 28 2013
MVFR CEILINGS ARE FORECAST TO PERSIST AT KVTN UNTIL 18Z/28TH. WHILE
THERE COULD BE TIMES WHEN CEILINGS GO VFR...THE RAP MODEL SEEM TO BE
HANDLING THE AREAS OF STRATUS BEST...KEEPING KVTN WITHIN THE STRATUS
AREA. KLBF SHOULD CONTINUE TO REMAIN IN VFR CONDITIONS THROUGH THE
PERIOD. CURRENT HIGH CLOUDINESS SHOULD THIN BY MID MORNING. SURFACE
WINDS SHOULD REMAIN LIGHT NORTHWEST BELOW 10KT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JACOBS
LONG TERM...TAYLOR
AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
135 AM CST THU FEB 28 2013
.SYNOPSIS...
ISSUED AT 253 PM CST WED FEB 27 2013
ANALYSIS OF THE 20Z MSL DATA SHOWED A FRONT ACROSS SOUTH DAKOTA TO A
LOW IN SOUTHEAST MONTANA. A WARM FRONT THEN EXTENDS THROUGH ALBERTA
AND BRITISH COLUMBIA TO A WAVE NORTHWEST OF VANCOUVER ISLAND AND
EVENTUALLY TO A LOW ON THE ALEUTIAN ISLANDS. WATER VAPOR IMAGERY
INDICATED A MATURING VORTEX IN THE PACIFIC NORTHWEST OF VANCOUVER
ISLAND AND ANOTHER BROAD CYCLONIC CIRCULATION ACROSS THE ALEUTIAN
CHAIN. NEARER TO HOME...A DEVELOPING WAVE WAS INDICATED IN THE WATER
VAPOR LOOP OVER NORTHEAST MONTANA. ANOTHER BROAD CYCLONIC
&&
.UPDATE...
ISSUED AT 130 AM CST THU FEB 28 2013
MADE ONLY MINOR REVISIONS TO THE FIRST 36 HRS OF THE
FORECAST...MAINLY TO ACCOUNT FOR THE STRATUS BACKING ACROSS
PORTIONS OF THE CENTRAL SANDHILLS AT THIS HOUR. STILL WATCHING FOR
THE POTENTIAL OF A FLURRY OR TWO THIS EVENING/OVERNIGHT AS A WEAK
DISTURBANCE DROPS THROUGH NORTHWESTERLY FLOW. PROXIMITY SOUNDINGS
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA REVEAL A BRIEF PERIOD OF
SATURATION WITHIN THE DENDRITIC LAYER...THUS WILL MAINTAIN THE
FLURRY MENTION THOUGH CONFIDENCES IN ANY NOTICEABLE QPF IS LOW.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 253 PM CST WED FEB 27 2013
FORECAST CONCERNS THROUGH THURSDAY ARE CLOUD COVER AND TEMPERATURES.
BAND OF STRATUS EXTENDED FROM WESTERN NORTH DAKOTA THROUGH WESTERN
AND CENTRAL NEBRASKA ON WEDNESDAY AFTERNOON. THIS IS IN AN AREA OF
BROAD FRONTOGENESIS...AND WITH NORTHERLY FLOW CONTINUING TO BRING
THIS MOISTURE SOUTH THROUGH TONIGHT...WILL KEEP THE CLOUD COVER IN
THIS SAME VICINITY. GOING INTO THURSDAY...A WEAK BOUNDARY IN THE LOW
LEVELS WILL REMAIN NEARLY STATIONARY ACROSS WESTERN NEBRASKA.
BELIEVE THE CORRIDOR OF WEAK FLOW WILL KEEP THE CLOUDS FROM ERODING
AND MAY KEEP THE STRATUS IN PLACE THROUGH MID DAY. BECAUSE OF THE
CLOUD COVER...DID BUMP TEMPERATURES UP A FEW DEGREES TONIGHT ACROSS
THE AREA WITH HIGHER CLOUD COVER AND THEN DID ADJUST HIGHS DOWN A
FEW DEGREES ON THURSDAY. WINDS WILL DIMINISH THIS EVENING ACROSS
MUCH OF THE FORECAST AREA...BUT NORTH CENTRAL NEBRASKA WILL KEEP
SOME BREEZY CONDITIONS THROUGH THE OVERNIGHT HOURS AND INTO
THURSDAY. HAVE ADDED SOME ISOLATED FLURRIES OR SPRINKLES TO THE
FORECAST FOR THURSDAY AFTERNOON OVER THE FAR NORTHWEST PART OF THE
FORECAST AREA AS A WEAK UPPER LEVEL SHORTWAVE TROUGH /CURRENTLY OVER
WESTERN MONTANA/ MOVES ACROSS SOUTHERN SOUTH DAKOTA. ALTHOUGH LIFT
ISN/T SUBSTANTIAL...AND MOISTURE IS LIMITED...BUT WITH THE NORTHWEST
FLOW...FELT IT WASN/T OUT OF THE QUESTION TO PUT IN THE LIGHT AND
NON-MEASURABLE PRECIPITATION.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 253 PM CST WED FEB 27 2013
ANOTHER SURGE OF COLD AIR WILL GENERATE SOME SYSTEM-RELATIVE
ISENTROPIC LIFT LATE THURSDAY NIGHT AND EARLY FRIDAY. AIR IN THE
285-295K LAYER IS NEARLY SATURATED WITH SATURATION DEFICITS OF 30MB
OR LOWER...BUT THE MIXING RATIOS ARE MOSTLY 2G/KG OR LOWER. LOOKING
IN THE DENDRITIC LAYER...UPWARD MOTION IS INDICATED WITH LAYER
RELATIVE HUMIDITY GREATER THAN 90 PERCENT. THEREFORE...SNOW CRYSTAL
FORMATION IS LIKELY. THE FORECAST SOUNDING INDICATES A PSEUDO-
ADIABATIC LAPSE RATE IN SATURATED AIR...SO SOME INSTABILITY IS
PRESENT AND SOME ACCRETION COULD BE EXPECTED. HOWEVER...WITH LITTLE
MOISTURE IN THE LOWER LAYERS...MOISTURE CONTENT WILL BE MINIMAL. AS
A RESULT...WE WILL INCLUDE ONLY FLURRIES IN THE FORECAST FOR
THURSDAY NIGHT AFTER MIDNIGHT AND FRIDAY.
FOR SATURDAY AND SUNDAY...AN UPPER RIDGE ACROSS THE WESTERN U.S.
WILL KEEP THE WEATHER IN NEBRASKA DRY AND UNSEASONABLY WARM.
THE NEXT SYSTEM OF NOTE IS A FAIRLY STRONG CLIPPER-TYPE SYSTEM
MONDAY AND MONDAY NIGHT. AN UPPER SYSTEM COMING FROM THE NORTH
PACIFIC AND ACROSS THE ROCKIES IN ALBERTA WILL TRIGGER LEE SIDE
CYCLOGENESIS IN SOUTHERN ALBERTA. THE CYCLONE WILL THEN MAKE ITS WAY
INTO THE NORTHERN U.S. AND ACROSS SOUTH DAKOTA AND NEBRASKA.
MOISTURE TRANSPORT VECTORS IN THE 290-300K LAYER SHOW MID-LEVEL
MOISTURE FROM THE PACIFIC CROSSING THE ROCKIES AND SATURATING MIDDLE
LEVELS BY SUNDAY EVENING 00Z. THIS WOULD HAVE MOISTURE IN PLACE FOR
THE STORM SYSTEM COMING ONTO THE NORTHERN PLAINS FROM ALBERTA. AN
EAST-WEST CROSS SECTION INDICATES DRY LOWER LAYERS
INITIALLY...SATURATING TOP DOWN MONDAY AFTERNOON. THE TOP-DOWN
SATURATION WILL RESULT IN FAIRLY RAPID COOLING IN THE BOUNDARY
LAYER. SO...IT LOOKS LIKE IT WILL BEGIN AS RAIN AND CHANGE OVER
QUICKLY TO SNOW BY LATE AFTERNOON OR EARLY EVENING. WITH THE TRACK
OF THE CYCLONE EXPECTED TO BE ACROSS NORTHERN NEBRASKA...THE BEST
CHANCES OF SIGNIFICANT PRECIPITATION WILL BE NORTHERN NEBRASKA.
THERE IS STILL SOME UNCERTAINTY WITH THE ECMWF INDICATING A TRACK
ACROSS SOUTHERN SOUTH DAKOTA...THE GFS INDICATING A TRACK ACROSS
CENTRAL NEBRASKA AND THE GEM INDICATING A TRACK ACROSS NORTHERN
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1115 PM CST WED FEB 27 2013
MVFR CEILINGS ARE FORECAST TO PERSIST AT KVTN UNTIL 18Z/28TH.
WHILE THERE COULD BE TIMES WHEN CEILINGS GO VFR...THE RAP MODEL
SEEM TO BE HANDLING THE AREAS OF STRATUS BEST...KEEPING KVTN
WITHIN THE STRATUS AREA. KLBF SHOULD CONTINUE TO REMAIN IN VFR
CONDITIONS THROUGH THE PERIOD. CURRENT HIGH CLOUDINESS SHOULD THIN
BY MID MORNING. SURFACE WINDS SHOULD REMAIN LIGHT NORTHWEST BELOW
10KT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JACOBS
SYNOPSIS...SPRINGER
SHORT TERM...BROOKS
LONG TERM...SPRINGER
AVIATION...ROBERG
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1115 PM CST WED FEB 27 2013
.SYNOPSIS...
ISSUED AT 253 PM CST WED FEB 27 2013
ANALYSIS OF THE 20Z MSL DATA SHOWED A FRONT ACROSS SOUTH DAKOTA TO A
LOW IN SOUTHEAST MONTANA. A WARM FRONT THEN EXTENDS THROUGH ALBERTA
AND BRITISH COLUMBIA TO A WAVE NORTHWEST OF VANCOUVER ISLAND AND
EVENTUALLY TO A LOW ON THE ALEUTIAN ISLANDS. WATER VAPOR IMAGERY
INDICATED A MATURING VORTEX IN THE PACIFIC NORTHWEST OF VANCOUVER
ISLAND AND ANOTHER BROAD CYCLONIC CIRCULATION ACROSS THE ALEUTIAN
CHAIN. NEARER TO HOME...A DEVELOPING WAVE WAS INDICATED IN THE WATER
VAPOR LOOP OVER NORTHEAST MONTANA. ANOTHER BROAD CYCLONIC
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 253 PM CST WED FEB 27 2013
FORECAST CONCERNS THROUGH THURSDAY ARE CLOUD COVER AND TEMPERATURES.
BAND OF STRATUS EXTENDED FROM WESTERN NORTH DAKOTA THROUGH WESTERN
AND CENTRAL NEBRASKA ON WEDNESDAY AFTERNOON. THIS IS IN AN AREA OF
BROAD FRONTOGENESIS...AND WITH NORTHERLY FLOW CONTINUING TO BRING
THIS MOISTURE SOUTH THROUGH TONIGHT...WILL KEEP THE CLOUD COVER IN
THIS SAME VICINITY. GOING INTO THURSDAY...A WEAK BOUNDARY IN THE LOW
LEVELS WILL REMAIN NEARLY STATIONARY ACROSS WESTERN NEBRASKA.
BELIEVE THE CORRIDOR OF WEAK FLOW WILL KEEP THE CLOUDS FROM ERODING
AND MAY KEEP THE STRATUS IN PLACE THROUGH MID DAY. BECAUSE OF THE
CLOUD COVER...DID BUMP TEMPERATURES UP A FEW DEGREES TONIGHT ACROSS
THE AREA WITH HIGHER CLOUD COVER AND THEN DID ADJUST HIGHS DOWN A
FEW DEGREES ON THURSDAY. WINDS WILL DIMINISH THIS EVENING ACROSS
MUCH OF THE FORECAST AREA...BUT NORTH CENTRAL NEBRASKA WILL KEEP
SOME BREEZY CONDITIONS THROUGH THE OVERNIGHT HOURS AND INTO
THURSDAY. HAVE ADDED SOME ISOLATED FLURRIES OR SPRINKLES TO THE
FORECAST FOR THURSDAY AFTERNOON OVER THE FAR NORTHWEST PART OF THE
FORECAST AREA AS A WEAK UPPER LEVEL SHORTWAVE TROUGH /CURRENTLY OVER
WESTERN MONTANA/ MOVES ACROSS SOUTHERN SOUTH DAKOTA. ALTHOUGH LIFT
ISN/T SUBSTANTIAL...AND MOISTURE IS LIMITED...BUT WITH THE NORTHWEST
FLOW...FELT IT WASN/T OUT OF THE QUESTION TO PUT IN THE LIGHT AND
NON-MEASURABLE PRECIPITATION.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 253 PM CST WED FEB 27 2013
ANOTHER SURGE OF COLD AIR WILL GENERATE SOME SYSTEM-RELATIVE
ISENTROPIC LIFT LATE THURSDAY NIGHT AND EARLY FRIDAY. AIR IN THE
285-295K LAYER IS NEARLY SATURATED WITH SATURATION DEFICITS OF 30MB
OR LOWER...BUT THE MIXING RATIOS ARE MOSTLY 2G/KG OR LOWER. LOOKING
IN THE DENDRITIC LAYER...UPWARD MOTION IS INDICATED WITH LAYER
RELATIVE HUMIDITY GREATER THAN 90 PERCENT. THEREFORE...SNOW CRYSTAL
FORMATION IS LIKELY. THE FORECAST SOUNDING INDICATES A PSEUDO-
ADIABATIC LAPSE RATE IN SATURATED AIR...SO SOME INSTABILITY IS
PRESENT AND SOME ACCRETION COULD BE EXPECTED. HOWEVER...WITH LITTLE
MOISTURE IN THE LOWER LAYERS...MOISTURE CONTENT WILL BE MINIMAL. AS
A RESULT...WE WILL INCLUDE ONLY FLURRIES IN THE FORECAST FOR
THURSDAY NIGHT AFTER MIDNIGHT AND FRIDAY.
FOR SATURDAY AND SUNDAY...AN UPPER RIDGE ACROSS THE WESTERN U.S.
WILL KEEP THE WEATHER IN NEBRASKA DRY AND UNSEASONABLY WARM.
THE NEXT SYSTEM OF NOTE IS A FAIRLY STRONG CLIPPER-TYPE SYSTEM
MONDAY AND MONDAY NIGHT. AN UPPER SYSTEM COMING FROM THE NORTH
PACIFIC AND ACROSS THE ROCKIES IN ALBERTA WILL TRIGGER LEE SIDE
CYCLOGENESIS IN SOUTHERN ALBERTA. THE CYCLONE WILL THEN MAKE ITS WAY
INTO THE NORTHERN U.S. AND ACROSS SOUTH DAKOTA AND NEBRASKA.
MOISTURE TRANSPORT VECTORS IN THE 290-300K LAYER SHOW MID-LEVEL
MOISTURE FROM THE PACIFIC CROSSING THE ROCKIES AND SATURATING MIDDLE
LEVELS BY SUNDAY EVENING 00Z. THIS WOULD HAVE MOISTURE IN PLACE FOR
THE STORM SYSTEM COMING ONTO THE NORTHERN PLAINS FROM ALBERTA. AN
EAST-WEST CROSS SECTION INDICATES DRY LOWER LAYERS
INITIALLY...SATURATING TOP DOWN MONDAY AFTERNOON. THE TOP-DOWN
SATURATION WILL RESULT IN FAIRLY RAPID COOLING IN THE BOUNDARY
LAYER. SO...IT LOOKS LIKE IT WILL BEGIN AS RAIN AND CHANGE OVER
QUICKLY TO SNOW BY LATE AFTERNOON OR EARLY EVENING. WITH THE TRACK
OF THE CYCLONE EXPECTED TO BE ACROSS NORTHERN NEBRASKA...THE BEST
CHANCES OF SIGNIFICANT PRECIPITATION WILL BE NORTHERN NEBRASKA.
THERE IS STILL SOME UNCERTAINTY WITH THE ECMWF INDICATING A TRACK
ACROSS SOUTHERN SOUTH DAKOTA...THE GFS INDICATING A TRACK ACROSS
CENTRAL NEBRASKA AND THE GEM INDICATING A TRACK ACROSS NORTHERN
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1115 PM CST WED FEB 27 2013
MVFR CEILINGS ARE FORECAST TO PERSIST AT KVTN UNTIL 18Z/28TH.
WHILE THERE COULD BE TIMES WHEN CEILINGS GO VFR...THE RAP MODEL
SEEM TO BE HANDLING THE AREAS OF STRATUS BEST...KEEPING KVTN
WITHIN THE STRATUS AREA. KLBF SHOULD CONTINUE TO REMAIN IN VFR
CONDITIONS THROUGH THE PERIOD. CURRENT HIGH CLOUDINESS SHOULD THIN
BY MID MORNING. SURFACE WINDS SHOULD REMAIN LIGHT NORTHWEST BELOW
10KT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...SPRINGER
SHORT TERM...BROOKS
LONG TERM...SPRINGER
AVIATION...ROBERG
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
901 PM CST FRI MAR 1 2013
.UPDATE...
THE LOW CLOUDS HAVE CLEARED WEST OF A LINE STRETCHING FROM
SHEBOYGAN TO WHITEWATER. TO THE EAST...LAKE EFFECT IS KEEPING THE
CLOUDS LOCKED IN AS WELL AS BRINGING A FEW LIGHT SNOW SHOWERS.
THESE SHOWERS ARE QUITE SHALLOW WITH AN INVERSION INDICATED AT
AROUND 2500-3000FT...VERY DRY ABOVE. DELTA T ISN/T BAD AT AROUND
12C. MKE IS REPORTING SOME 10 MILE LIGHT SNOW...ABOUT WHAT CAN BE
EXPECTED IN THE SOUTHEAST OVERNIGHT. ANY ACCUMS WOULD BE A LIGHT
DUSTING.
WHERE SKIES HAVE CLEARED...TEMPS ARE DROPPING QUICKLY. THE CIRRUS
OVERHEAD IS VERY THIN WITH THE LOW CLOUDS VISIBLE BENEATH IT USING
THE 11U-3.9U SATELLITE PRODUCT. MIDDLETON ALREADY REPORTING 9F.
HAVE ALREADY DROPPED LOWS FOR TONIGHT AND WILL HAVE TO WATCH THE
TRENDS.
&&
.AVIATION/06Z TAFS/...
EXPECT LAKE EFFECT SNOW SHOWERS ON AND OFF AT THE SOUTHEAST WI TAF
SITES THROUGH MUCH OF THE NIGHT...DIMINISHING BY AROUND 12Z.
VISIBILITY SHOULD REMAIN AT 5 MI OR BETTER AND ANY ACCUMS WILL BE
LESS THAN 1/2 INCH...OR BARELY A DUSTING. EXPECT CIGS TO CLEAR OUT
OF THE SOUTHEAST BY OR SHORTLY AFTER 12Z WITH VFR CONDITIONS
CONTINUING THROUGH THE REMAINDER OF THE TAF PERIOD. KMSN HAS
ALREADY CLEARED AND VFR CONDITIONS ARE EXPECTED THROUGH THE TAF
PERIOD. EXPECT NORTHERLY WINDS OF 6 TO 12 MPH.
&&
.PREV DISCUSSION... /ISSUED 326 PM CST FRI MAR 1 2013/
SHORT TERM...
TONIGHT AND SATURDAY...FORECAST CONFIDENCE IS MEDIUM
BAND OF LIGHT SNOW SHOWERS HAS WEAKENED TO FLURRIES FROM NEAR
MADISON TO FOND DU LAC...AND SHOULD CONTINUE TO WEAKEN THROUGH
SUNSET...AS DRIER AIR WORKS INTO THE AREA. ANY FLURRIES SHOULD
DISSIPATE ACROSS MOST OF THE REST OF THE AREA SHOULD DISSIPATE BY
EVENING AS WELL...EXCEPT FOR LIGHT LAKE EFFECT SNOW SHOWERS/FLURRIES
NEAR THE SHORELINE EAST AND SOUTHEAST OF MILWAUKEE.
MARGINAL DELTA T VALUES OF 12 TO 14 DEGREES CELSIUS...FAVORABLE
NORTH NORTHEAST FETCH...AND MODEST LOW LEVEL CONVERGENCE MOVING
TOWARD THIS AREA THIS EVENING MAY BRING THIS BAND ONSHORE. HRRR AND
LOCAL WRF 4KM MODELS TRY TO DO THIS...THEN TRY TO SHIFT IT BACK
OFFSHORE AFTER 06Z SATURDAY. LEFT SCATTERED POPS FOR LIGHT SNOW
SHOWERS SOUTH OF MILWAUKEE NEAR THE LAKE TONIGHT. A FEW TENTHS OF AN
INCH COULD FALL IF THESE BANDS MAKE IT ONSHORE. LOW LEVEL FLOW
BECOMES MORE NORTHERLY SATURDAY...WHICH SHOULD KEEP THIS BAND
OFFSHORE. LEFT FLURRIES IN THE FAR SOUTHEAST...WITH LOW LEVEL
MOISTURE LINGERING WITHIN DENDRITE ZONE.
CLOUDS SHOULD GRADUALLY MIX OUT FROM NORTHWEST TO SOUTHEAST ACROSS
THE AREA TONIGHT...AND FINALLY MIX OUT IN THE FAR SOUTHEAST COUNTIES
BY SATURDAY AFTERNOON AS LAKE EFFECT CLOUDS MOVE OFF TO THE
SOUTHEAST. TEMPERATURES WILL BE BELOW SEASONAL NORMALS TONIGHT AND
SATURDAY...WITH 10 TO 15 INLAND WITH AT LEAST PARTIAL CLEARING...AND
UPPER TEENS WITH MORE CLOUDS IN THE FAR SOUTHEAST COUNTIES NEAR THE
LAKE. HIGHS IN THE MID TO UPPER 20S SEEM REASONABLE FOR SATURDAY.
SATURDAY NIGHT THROUGH TUESDAY...FORECAST CONFIDENCE MEDIUM
SFC HIGH PRESSURE TO SETTLE OVER THE REGION SAT NT AND SUN. A
SHORTWAVE TROUGH WILL TRACK DUE SOUTH FROM CANADA TO LOWER MI FOR
THIS TIME PERIOD BUT AIRMASS REMAINS DRY. MID TO HIGH CLOUDS WILL
BE INCREASING LATE SAT NT INTO SUNDAY WITH WARM ADVECTION ALOFT
AND RIDGING. RIDGING IS IN RESPONSE TO A STRONG SHORTWAVE TROUGH
OVER MT THAT WILL MOVE TO THE MIDDLE MS RIVER VALLEY ON TUE AND TO
THE EAST COAST FOR WED. RUN TO RUN MODEL CONSISTENCY IS
STRUGGLING WITH THE EXACT TRACK OF THE STRONG SHORTWAVE
TROUGH. HOWEVER...LATEST MODELS HAVE FAIRLY GOOD AGREEMENT MINUS THE
OUTLIER OF THE NAM. WILL STILL ACCOUNT FOR THE LACK OF RUN TO RUN
CONSISTENCY HOWEVER AND FORECAST SMALL CHANCES OF LIGHT SNOW
BEGINNING LATE SUN NT OVER SOUTH CENTRAL WI AND THEN SPREADING
EAST WITH CHANCES OF LIGHT SNOW THROUGH TUE NT. EXPECT THE MAIN
AXIS OF SNOW TO REMAIN MOSTLY ACROSS IA AND IL WITH BEST CHANCES
FOR THE NRN PORTION OF THE SNOW TO AFFECT SRN WI ON TUE.
WENT WITH FAIRLY COLD TEMPS SAT NT AND SUN NT DUE TO GOOD
RADIATIONAL COOLING WITHIN A POLAR HIGH. THE CLOUDS WILL ARRIVE TOO
LATE ON SAT NT FOR MUCH EFFECT AND ONLY PTLY CLOUDY CONDITIONS
ARE FORECAST FOR SUN NT. 925 MB TEMPS SUGGEST HIGHS WILL BE AROUND
30F FOR SUN-TUE.
LONG TERM...
WEDNESDAY THROUGH FRIDAY...FORECAST CONFIDENCE MEDIUM
RIDGING ALOFT IS EXPECTED FOR WED INTO THU AS A LONGWAVE POLAR
TROUGH MOVES INTO THE WRN USA. AT THE SFC...POLAR HIGH PRESSURE
WILL PREVAIL DURING THIS TIME BUT IT MAY MOVE EAST BY THU
AFTERNOON ALLOWING SLY WINDS TO DEVELOP WITH MILDER TEMPS. BELOW
NORMAL TEMPS ARE EXPECTED BEFOREHAND. A SHORTWAVE TROUGH AND LOW
PRESSURE AREA WILL THEN MOVE NEWD THROUGH THE NRN PLAINS AND MN
FOR THU AND THU NT WITH SLIGHT CHANCES OF LIGHT SNOW OVER SRN WI
DUE TO WARM ADVECTION. SLY WINDS WILL CONTINUE ON FRI AS THE LOW
TRACKS ENEWD ACROSS ONTARIO CANADA. THUS MILD HIGH TEMPS IN THE
40S ARE EXPECTED.
AVIATION/00Z TAFS/...
FOR MADISON AND WAUKESHA TAF SITES...EXPECT FLURRIES TO LINGER UNTIL
AROUND 00Z SATURDAY. VFR VISIBILITIES ARE EXPECTED...WITH CEILINGS
REMAINING BELOW FUEL ALTERNATE THRESHOLDS LATE THIS AFTERNOON AND
PERHAPS THROUGH EARLY THIS EVENING...BEFORE DRIER AIR MIXES OUT THE
CEILINGS LATER THIS EVENING INTO EARLY SATURDAY. GUSTY NORTH
NORTHEAST WINDS LATE THIS AFTERNOON WILL DIMINISH THIS
EVENING...WITH MODEST NORTH WINDS THROUGH SATURDAY.
FOR MILWAUKEE AND KENOSHA TAF SITES...EXPECT LIGHT LAKE EFFECT SNOW
SHOWERS/FLURRIES TO LINGER THROUGH MOST OF TONIGHT...BUT DIMINISH IN
AREAL COVERAGE. A FEW TENTHS OF AN INCH OF ACCUMULATION ARE POSSIBLE
WITH ANY PERSISTENT LIGHT SNOW BANDS...MAINLY AT KENOSHA. MAINLY VFR
VISIBILITIES EXPECTED.
CEILINGS REMAIN BELOW FUEL ALTERNATES THROUGH MOST OF
TONIGHT...BEFORE MIXING OUT BY MID TO LATE SATURDAY MORNING WITH
DRIER AIR MOVING INTO THE AREA. GUSTY NORTH WINDS LATE THIS
AFTERNOON WILL REMAIN SOMEWHAT GUSTY TONIGHT INTO EARLY
SATURDAY...REMAINING NORTHERLY ON SATURDAY.
MARINE...
SMALL CRAFT ADVISORY HAS BEEN EXTENDED UNTIL 09Z SUNDAY ACROSS THE
NEARSHORE WATERS OF LAKE MICHIGAN. TIGHT PRESSURE GRADIENT WILL
REMAIN ACROSS THIS AREA INTO SATURDAY MORNING...BEFORE GRADUALLY
RELAXING DURING THE AFTERNOON. GUSTY NORTH WINDS OF 15 TO 25 KNOTS
WITH GUSTS TO AROUND 30 KNOTS ARE EXPECTED THROUGH TONIGHT...THEN
SLOWLY DECREASE ON SATURDAY.
HIGH WAVES OF 6 TO 9 FEET THIS EVENING WILL GRADUALLY SUBSIDE
THROUGH SATURDAY NIGHT...AS WINDS REMAIN NORTH BEFORE BACKING
NORTHWEST.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 3 AM CST SUNDAY FOR LMZ643>646.
&&
$$
UPDATE...DAVIS
TONIGHT/SATURDAY AND AVIATION/MARINE...WOOD
SATURDAY NIGHT THROUGH FRIDAY...GEHRING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
315 PM CST THU FEB 28 2013
.SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT
315 PM CST THU FEB 28 2013
AT 3 PM...CLOUDS CONTINUE TO PIVOT AROUND A LOW PRESSURE SYSTEM
CENTERED OVER SOUTHEAST ONTARIO. HOWEVER SOME DRIER AIR FILTERING
INTO NORTHERN MINNESOTA...UPPER MICHIGAN...AND NORTHERN WISCONSIN
IS CAUSING SOME BREAKS TO DEVELOP IN THE MVRF DECK. BUFKIT SOUNDINGS
SUGGEST THAT THE CLOUDS WILL LINGER ACROSS THE FORECAST AREA
TONIGHT...AND THEN GRADUALLY BREAK UP FROM NORTHEAST TO SOUTHWEST
ON FRIDAY. AT THE SAME TIME...SOME MID AND HIGH CLOUDS WILL BE
MOVING INTO THE AREA FROM THE WEST AS A WEAKENING SHORT WAVE
/CURRENTLY OVER THE DAKOTAS/ MOVES EAST TOWARD THE FORECAST AREA.
WITH SKIES EXPECTED TO REMAIN CLOUDY TONIGHT...ONCE AGAIN WENT
HIGHER THAN THE MAV AND MET MOS TEMPERATURES. A 50-50 BLEND
OF LAST NIGHT/S MINIMUM TEMPERATURES AND THE BIAS CORRECTED
CONSALL...RAISED THE MINIMUM TEMPERATURES INTO THE MID AND
UPPER TEENS ACROSS NORTH-CENTRAL WISCONSIN...AND LOWER AND MID 20S
ACROSS THE REMAINDER OF THE FORECAST AREA. THIS SEEMS MUCH MORE
REALISTIC THAN THE MOS.
ALSO FOR TONIGHT...A WEAK 850-700 MB WILL MOVE SOUTH THROUGH
THE AREA TONIGHT. IN ADDITION...THERE IS SOME WEAK 275 ISENTROPIC
LIFT. SOUNDINGS SUGGEST THAT THE OMEGA ASSOCIATED WITH THIS
FEATURE WILL BE CO-LOCATED WITH THE LOW LEVEL MOISTURE. AS A
RESULT...KEPT SCATTERED FLURRIES IN THE FORECAST.
ON SATURDAY NIGHT...THE MODELS SHOW THAT A WEAKENING TROUGH WILL
MOVE INTO THE UPPER LEVEL RIDGE. WEAK TO MODERATE 280K ISENTROPIC
LIFT DEVELOPS AHEAD OF THIS TROUGH. THE 28.00Z NAM/WRF CONTINUES
TO SHOW SOME LIGHT PRECIPITATION ASSOCIATED WITH THIS SYSTEM.
THE ECMWF GENERATES SOME FLURRIES WITH THIS SYSTEM. MEANWHILE THE
GEM AND OPERATIONAL GFS KEEPS THE AREA DRY. LOOKING AT THE 12 GFS
MEMBERS...ONLY 3 OF THEM GENERATE ANY MEASURABLE PRECIPITATION.
THE MAIN DIFFERENCE BETWEEN THE GFS AND NAM IN THE BUFKIT
SOUNDINGS IS HOW THEY HANDLE THE DRY AIR BELOW 5K FEET. THE
NAM/WRF SATURATES THIS LAYER. MEANWHILE THE GFS SHOWS THAT THIS
LAYER WILL REMAIN VERY DRY. WITH UNCERTAINTIES IN THE LOW LEVEL
MOISTURE...JUST OPTED TO GO WITH FLURRIES AT THIS TIME.
.LONG TERM...SUNDAY THROUGH THURSDAY
315 PM CST THU FEB 28 2013
FROM LATE SUNDAY NIGHT INTO TUESDAY...THE MAIN FORECAST CONCERN IS
THE TRACK OF A LOW PRESSURE SYSTEM MOVING THROUGH THE REGION. BOTH
THE GFS AND ECMWF HAVE SHIFTED THE TRACK OF THIS LOW EVEN FURTHER
SOUTH OF ITS TRACK AT 28.00Z AND 28.06Z. WITH THIS TRACK...IT
WOULD ONLY AFFECT SOUTHEAST MINNESOTA AND NORTHEAST IOWA. MEANWHILE
THE GEM KEEPS THE SYSTEM TRACKING TO OUR NORTH. WITH THIS
TRACK...IT CONTINUES TO PRODUCE PRECIPITATION ACROSS THE ENTIRE
AREA. WITH THE MODELS STILL TRYING TO SORT OUT THINGS...OPTED TO
STAY WILL ALL BLEND FOR NOW.
BEYOND THIS TIME PERIOD...IT CONTINUES TO LOOK LIKE A 500 MB RIDGE
WILL DEVELOP ACROSS THE CENTRAL UNITED STATES. AS STATED
YESTERDAY...THIS IS ACTUALLY SUPPORTED BY MADDEN JULIAN
OSCILLATIONS FOR PHASES 6 AND 7. WHILE THERE IS AGREEMENT THAT
THIS RIDGE WILL BE BUILDING ACROSS THE AREA...THERE IS STILL SOME
UNCERTAINTY ON HOW WARM WE WILL GET.
&&
.AVIATION...THROUGH 18Z FRIDAY
1130 AM CST THU FEB 28 2013
MAIN AVIATION CONCERN THROUGH THE TAF PERIOD IS THE ERODING OF LOW
STRATUS/MVFR CEILINGS ACROSS THE UPPER GREAT LAKES REGION TONIGHT. LATEST
WATER VAPOR SATELLITE IMAGERY AND SURFACE ANALYSIS SHOW AREA REMAINS
UNDER THE INFLUENCE OF LOW PRESSURE OVER THE EASTERN GREAT LAKES AND
CONTINUES TO WRAP LOW LEVEL MOISTURE/STRATUS DECK INTO THE REGION.
LATEST METARS INDICATE MVFR CEILING CONDITIONS PREVAILING ACROSS
MUCH OF THE AREA. LATEST 28.12Z NAM AND 28.15Z RAP ARE HINTING AT
DRIER AIR OVER SOUTHERN ONTARIO TO ADVECT INTO THE REGION AFTER
03Z FRIDAY. THE 28.12Z NAM IS INDICATING A SLOWER TREND WITH THE
DRIER AIR ADVECTING INTO THE REGION THAN PREVIOUS MODELS RUNS.
CONFIDENCE IS HIGHER THE LOW STRATUS DECK/MVFR CEILINGS WILL ERODE
WITH TIME OVER THE AREA...HOWEVER TIMING OF SKIES CLEARING OUT AND
CONDITIONS BECOMING VFR AT BOTH TAF SITES APPEAR TO BE LATER THAN
PREVIOUS FORECAST. CONFIDENCE IN FORECAST NOT AS HIGH WITH
TIMING. AT THIS TIME...WILL DELAY THE SKIES CLEARING OUT AT BOTH
THE LSE AND RST TAF SITES BETWEEN 05-07Z FRIDAY TIME FRAME. AFTER
07Z FRIDAY VFR CONDITIONS WILL PREVAIL AT TAF SITES.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
228 PM CST THU FEB 28 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...DTJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1130 AM CST THU FEB 28 2013
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
346 AM CST THU FEB 28 2013
MAIN FORECAST CONCERNS THIS PACKAGE...FLURRY/-SHSN CHANCES TODAY AND
AGAIN SAT NIGHT...CLOUDS/TEMPERATURES THRU THE PERIOD.
06Z DATA ANALYSIS HAD A BROAD AREA OF LOW PRESSURE OVER THE NORTH-
EAST CONUS WITH ITS CIRCULATION SPREAD WELL BACK TO THE MID/UPPER MS
VALLEY. MOISTURE...WEAK SHORTWAVES AND LIFT CONTINUED TO ROTATE
AROUND THE BROAD SFC-MID LEVEL LOW AND SOUTHWEST ACROSS WI/EASTERN
MN/IA AT MIDNIGHT...WITH PATCHY TO AREAS OF -SN PERSISTING ACROSS
THE AREA. TIME LAPSE OF AREA RADARS DID SHOW A GRADUAL DECREASE OF
THE -SN COVERAGE/INTENSITY SINCE 03Z...AS THE LOWS SLOWLY MOVE
EAST AND THE AREA GETS FURTHER AND FURTHER FROM THE MOISTURE SOURCE/
FORCING/LIFT WEAKEN. EARLY MORNING TEMPS REMAINED ON THE MILD SIDE
ACROSS MUCH OF THE REGION...MOSTLY IN THE MID 20S TO LOWER 30S UNDER
THE CLOUD BLANKET.
28.00Z MODELS INITIALIZED RATHER WELL. SOLUTIONS QUITE SIMILAR FOR
TODAY THRU FRI NIGHT...THEN DIFFERENCES APPEAR FOR SAT/SAT NIGHT
AS A NORTHERN STREAM SHORTWAVE DROPS INTO THE UPPER MIDWEST.
DPROG/DT OF 500MB HGTS AT 28.00Z SHOWED THE MODEL RUNS OF 26.00Z AND
27.00Z VERIFIED REASONABLY WELL ACROSS NOAM/EASTERN PAC...HOWEVER
PLENTY OF DETAIL NOISE AS THEY CONVERGED ON THE NORTHEAST CONUS LOW
POSITION/STRENGTH. TREND HAS ALSO BEEN STRONGER WITH A SHORTWAVE
APPROACHING THE BC COAST. CONSISTENCY IMPROVING FOR TODAY THRU FRI
NIGHT AS THE FLOW OVER WESTERN/CENTRAL NOAM AMPLIFIES AND THE
NORTHEAST CONUS LOW MOVES EAST. MODEL DIFFERENCES BEGIN TO EMERGE/
INCREASE FOR SAT/SAT NIGHT AS THE RIDGE AXIS MOVES EAST AND
SHORTWAVE ENERGY DROPS DOWN ITS EASTERN SIDE INTO THE UPPER MIDWEST.
NO ONE MODEL WITH BETTER RUN-TO-RUN CONSISTENCY IN THE TODAY THRU
SAT NIGHT PERIOD. CHECK OF OBS VS. MODEL DATA AT 06Z SHOWED ALL TO
BE QUITE GOOD WITH THE CENTRAL/EASTERN CONUS SFC FIELDS. A MODEL
BLEND AGAIN LOOKED TO BE QUITE GOOD WITH THE 00-06Z PRECIP OVER THE
EAST HALF OF THE CONUS. PER WV IMAGERY...ALL LOOKED VERY REASONABLE
WITH THE SHORTWAVE DETAILS OVER NOAM WITH PERHAPS A SLIGHT EDGE TO
THE ECMWF/GEM. NO MODEL FAVORITE THIS CYCLE AND WITH THE TREND
TOWARD AN IMPROVING CONSENSUS AT LEAST THRU FRI NIGHT...FAVORED THE
MODEL/ENSEMBLE CONSENSUS. SHORT TERM FCST CONFIDENCE GOOD THRU FRI
NIGHT THEN AVERAGE SAT/SAT NIGHT.
FOR THE SHORT TERM...SFC-700MB AIRMASS CONTINUES TO SLOWLY DRY
EARLY THIS MORNING. THIS WITH DECREASING FORCING/LIFT AND AN
INCREASING INVERSION IN THE 900-850MB LAYER. MORE WIDESPREAD -SN
COMES TO AN END BY SUNRISE. MODEL SOUNDINGS DO SHOW SOME STEEP SFC
TO 900 OR 850MB LAPSE RATES BY MID-DAY AND FOR THE AFTERNOON...ALONG
WITH ABOUT 75MB WORTH OF MOISTURE TRAPPED UNDER THE INVERSION.
QUESTION IS WILL THE DEPTH OF STEEP LAPSE RATES UNDER THE INVERSION
COMBINED WITH WEAK CYCLONIC CONVERGENCE BE ENOUGH TO GENERATE SOME
FLURRIES/-SHSN TODAY. PREVIOUS GRID SET CARRIED SCT FLURRIES FOR
TODAY AND WILL LEAVE THIS FOR NOW. WITH ALL THE MOISTURE TRAPPED
UNDER THE INVERSION...LEFT SKIES TODAY MOSTLY CLOUDY TO CLOUDY.
CANADIAN HIGH PRESSURE CONTINUES TO BUILD IN TONIGHT WITH CONTINUED
DRYING ALOFT AND UNDER THE INVERSION. HOWEVER PLENTY OF HIGH LEVEL
MOISTURE/CLOUDS...WITH WEAK SHORTWAVES DROPPING DOWN THE EAST SIDE
OF THE BUILDING WESTERN NOAM RIDGE...PROGGED TO REMAIN OVER THE AREA
TONIGHT INTO FRI. LOOKS AS THOUGH CLOUDS WILL BE SLOW TO DECREASE
TONIGHT/FRI...AND TRENDED CLOUD COVER UPWARD THESE PERIODS. CLOUDS
WILL HELP HOLD TEMPS DOWN TODAY/FRI AND UP A BIT TONIGHT AS COLDER
925-850MB AIR SLOWLY ADVECTS INTO THE AREA. GIVEN THE SHALLOW DEPTH
OF LOW LEVEL MOISTURE AND THE INVERSION...LEFT TONIGHT/FRI DRY. DEEP
LAYERED DRYING CONTINUES FRI NIGHT WITH THE SFC RIDGE AXIS SETTLING
OVER THE AREA. REMAINED OPTIMISTIC FOR CLEARING FRI NIGHT. CLEARING
SKIES...LIGHT WINDS AND 925MB TEMPS IN THE -8 TO -12C RANGE...FRI
NIGHT LOOKS TO BE ONE OF THE COLDER NIGHTS OF LATE.
MODELS ALL INDICATING A STRONGER NORTHERN STREAM SHORTWAVE TO DROP
SOUTHEAST TOWARD AND INTO THE REGION SAT/SAT NIGHT. NAM THE FURTHEST
WEST WITH THIS FEATURE BUT OVERALL TREND OF MODELS IS TO THE WEST.
STRONGER NAM BRINGS SOME 275-285K ISENTROPIC LIFT AND 500-300MB PV
ADVECTION WITH THE SHORTWAVE INTO/ACROSS THE AREA SAT AFTERNOON/
EVENING...AND SOME SFC-700MB MOISTURE INTO THE AREA SAT EVENING.
WITH THE WESTWARD TREND AMONG THE MODELS...HONORED THE NAM FOR NOW
WITH A SMALL -SN CHANCE OVER THE WEST HALF OF THE FCST AREA SAT
EVENING. RAISED CLOUD COVER AND LOWS A BIT FOR SAT NIGHT AS WELL.
FAVORING THE MODEL/ENSEMBLE CONSENSUS...PREFERRED A BLEND OF THE
NUMERICAL TEMP GUIDANCE FOR HIGHS/LOWS TODAY THRU SAT NIGHT. WITH
LIGHT WINDS AND POTENTIAL FOR CLEAR SKIES OVER THE SNOW COVERED
LANDSCAPE...DID TREND A BIT TOWARD COLDER OF GUIDANCE LOWS FRI
NIGHT.
.LONG TERM...SUNDAY THROUGH WEDNESDAY
346 AM CST THU FEB 28 2013
28.00Z MEDIUM RANGE MODELS IN DECENT AGREEMENT ON SUN FOR RIDGING TO
BE PUSHED EAST OVER THE NORTH-CENTRAL CONUS. THIS AS THE NEXT STRONG
SHORTWAVE TROUGH DIGS INTO THE NORTHERN ROCKIES. BY MON/TUE...MODELS
CONTINUE TO DIFFER ON THE STRENGTH/TRACK OF THIS FEATURES AT IS
DROPS INTO THE CENTRAL PLAINS MON THEN TRACKS INTO EITHER THE MID OR
UPPER MS VALLEY TUE. UKMET/ECMWF MORE SOUTHERN SOLUTIONS...GFS/GEM
MORE NORTHERN AND WOULD SPREAD A ROUND OF ACCUMULATING SNOW ACROSS
MUCH OF THE FCST AREA MON INTO TUE. ENSEMBLES SHOW CONSIDERABLE
SPREAD AMONG THEIR MEMBERS IN THE MON/TUE TIME-FRAME THUS THE VARIED
DETERMINISTIC MODEL SOLUTIONS NOT UNEXPECTED. FCST CONFIDENCE FOR
MON/TUE ON THE LOW SIDE AT THIS TIME. PER THE MODEL/ENSEMBLE
CONSENSUS...SNOW CHANCES MON/MON NIGHT MOSTLY IN THE 25-55 PERCENT
RANGE MON/MON NIGHT /HIGHEST ACROSS THE SOUTHWEST END/. THESE
PROVIDE SOME CONTINUITY WITH THE PREVIOUS FCST AND ACCEPTABLE FOR
NOW UNTIL MODEL NOISE DECREASES AND A BETTER CONSENSUS DEVELOPS.
BETTER MODEL CONSENSUS/AND IMPROVED FCST CONFIDENCE ON WED...FOR SFC
HIGH PRESSURE AND RIDGING ALOFT TO BUILD ACROSS THE MID/UPPER MS
VALLEY. MODEL/ENSEMBLE CONSENSUS TEMPS NEAR THE SEASONAL NORMALS FOR
SUN-WED LOOKS REASONABLE FOR NOW.
&&
.AVIATION...THROUGH 18Z FRIDAY
1130 AM CST THU FEB 28 2013
MAIN AVIATION CONCERN THROUGH THE TAF PERIOD IS THE ERODING OF LOW
STRATUS/MVFR CEILINGS ACROSS THE UPPER GREAT LAKES REGION TONIGHT. LATEST
WATER VAPOR SATELLITE IMAGERY AND SURFACE ANALYSIS SHOW AREA REMAINS
UNDER THE INFLUENCE OF LOW PRESSURE OVER THE EASTERN GREAT LAKES AND
CONTINUES TO WRAP LOW LEVEL MOISTURE/STRATUS DECK INTO THE REGION.
LATEST METARS INDICATE MVFR CEILING CONDITIONS PREVAILING ACROSS
MUCH OF THE AREA. LATEST 28.12Z NAM AND 28.15Z RAP ARE HINTING AT
DRIER AIR OVER SOUTHERN ONTARIO TO ADVECT INTO THE REGION AFTER
03Z FRIDAY. THE 28.12Z NAM IS INDICATING A SLOWER TREND WITH THE
DRIER AIR ADVECTING INTO THE REGION THAN PREVIOUS MODELS RUNS.
CONFIDENCE IS HIGHER THE LOW STRATUS DECK/MVFR CEILINGS WILL ERODE
WITH TIME OVER THE AREA...HOWEVER TIMING OF SKIES CLEARING OUT AND
CONDITIONS BECOMING VFR AT BOTH TAF SITES APPEAR TO BE LATER THAN
PREVIOUS FORECAST. CONFIDENCE IN FORECAST NOT AS HIGH WITH
TIMING. AT THIS TIME...WILL DELAY THE SKIES CLEARING OUT AT BOTH
THE LSE AND RST TAF SITES BETWEEN 05-07Z FRIDAY TIME FRAME. AFTER
07Z FRIDAY VFR CONDITIONS WILL PREVAIL AT TAF SITES.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
346 AM CST THU FEB 28 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...DTJ
AREA FORECAST DISCUSSION
NWS LINCOLN IL
240 AM CST SAT MAR 2 2013
.DISCUSSION...
ISSUED 240 AM CST SAT MAR 2 2013
PESKY LONG-LASTING LIGHT SNOW IS FINALLY BEGINNING TO EXIT THE
AREA...AND WAS MAINLY SOUTH OF I-70 EARLY THIS MORNING. LOW CLOUD
DECK HAS BEEN ERODING FROM THE NORTH AND SOME BREAKS HAVE
DEVELOPED AS FAR SOUTH AS PEORIA...BUT STILL PLENTY OF CLOUDINESS
OVER THE AREA.
MAIN FORECAST CONCERNS INVOLVE PRECIPITATION CHANCES EARLY NEXT
WEEK.
SHORT TERM...TODAY THROUGH TUESDAY...
MOSTLY DRY CONDITIONS EXPECTED TODAY FOR A CHANGE. WILL NEED TO
MONITOR FOR SOME LINGERING LIGHT SNOW SHOWERS ACROSS THE EASTERN
CWA TODAY...ESPECIALLY WITH THE WIND TRAJECTORY COMING OFF LAKE
MICHIGAN. CLOUDS MAY BE A BIT SLOWER TO ERODE...WITH 925-850 MB
HUMIDITY PLOT OFF THE RAP MODEL KEEPING A FAIR AMOUNT OF
CLOUDINESS EAST OF I-55 WELL INTO THE AFTERNOON. HOWEVER...
CLEARING LATER TODAY AND TONIGHT WILL PRECEDE A RIDGE OF HIGH
PRESSURE THAT WILL CROSS THE STATE ON SUNDAY.
DEEP UPPER TROUGHING OVER THE EASTERN U.S. TO PUSH EASTWARD ON
SUNDAY...AS A SHORTWAVE IN SOUTHWEST CANADA BEGINS TO CLOSE OFF
AND DROP INTO THE NORTHERN PLAINS EARLY NEXT WEEK. PRECIP CHANCES
EARLY NEXT WEEK WILL FOCUS ON A COUPLE FEATURES. THE FIRST WILL BE
WITH THE STRONG WARM AIR ADVECTION THAT WILL TAKE PLACE LATE
SUNDAY NIGHT...WITH EVENING MODELS IN FAIRLY GOOD AGREEMENT IN
DEVELOPMENT OF SOME LIGHT SNOW ACROSS THE WESTERN CWA AFTER
MIDNIGHT...AND SPREADING OVER MUCH OF THE CWA ON MONDAY. SHOULD
SEE SOME TRANSITION OVER TO RAIN DURING THE DAY ACROSS THE SOUTH
HALF OF THE FORECAST AREA...AS TEMPERATURES RISE TO AROUND THE 40
DEGREE MARK. SECOND FOCUS WILL BE AS LOW PRESSURE DEVELOPS OVER
THE CENTRAL PLAINS AND TOWARD THE WESTERN OHIO VALLEY BY TUESDAY
MORNING...WITH AN INVERTED SURFACE TROUGH EXTENDING NORTHWEST
TOWARD THE UPPER LOW. HAVE MAINTAINED HEALTHY PRECIP CHANCES
THROUGH TUESDAY WITH THESE FEATURES...MOSTLY AS SNOW BUT WITH SOME
RAIN ACROSS THE SOUTHEAST. POTENTIAL EXISTS FOR ANOTHER 1 TO 3
INCHES OF SNOW EARLY NEXT WEEK.
LONG TERM...WEDNESDAY THROUGH FRIDAY...
UPPER LOW SHOULD MAKE SOME STEADY PROGRESS SOUTHEAST AND FORM A
STRONG STORM SYSTEM OFF THE CAROLINA COAST BY MIDWEEK. THIS WILL
ALLOW FOR SOME UPPER RIDGING ACROSS THE CENTER OF THE NATION...
WITH MODERATING TEMPERATURES AS A SOUTHWEST UPPER FLOW SETS UP
LATER IN THE WEEK...AND HIGHS ARE LIKELY TO RETURN TO THE 50S BY
FRIDAY. ANY PRECIPITATION IS EXPECTED TO HOLD OFF UNTIL NEXT
WEEKEND...BEYOND THE CURRENT FORECAST PERIOD.
GEELHART
&&
.AVIATION...
ISSUED 1152 PM CST FRI MAR 1 2013...FOR THE 06Z TAFS
MVFR CONDITIONS WILL LIKELY LINGER THROUGH MUCH OF THE MORNING AT
THE TERMINAL SITES. THE NORTHERN TERMINALS WILL HAVE THE BETTER
CHANCES OF SEEING CLEARING ARRIVE FIRST...POSSIBLY IN THE MID TO
LATE MORNING. THE DRY NORTHERLY WINDS AT THE SURFACE AND ALOFT
WILL WORK TO ERODE THE CLOUD LAYER FROM N TO S. LITTLE TO NO SNOW
ACCUMULATION IS EXPECTED...BUT E-W RUNWAYS MAY SEE SOME LIGHT SNOW
ACCUMULATION AGAINST THE GRASS AS NORTH WINDS BLOW ANY LOOSE SNOW
ACROSS TRAVEL SURFACES...POSSIBLY MAKING THEM SLIPPERY.
WIND DIRECTIONS WILL REMAIN NORTH UNTIL LATER ON SATURDAY OR SAT
EVE WHEN WINDS BECOME MORE NW. WIND SPEEDS WILL DIP BELOW 10KT SAT
EVE DUE TO ADVANCING HIGH PRESSURE AND WEAKENING PRESSURE GRADIENT.
SHIMON
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
324 AM CST SAT MAR 2 2013
.SYNOPSIS...
LATEST IR SATELLITE IMAGERY INDICATED THE NORTH TO SOUTH CLEARING
TREND OF LOW CLOUDS HAD COME TO A HALT ROUGHLY ALONG THE I-80
CORRIDOR OVER THE PAST FEW HOURS. SURFACE ANALYSIS INDICATED A LEE
TROUGH ACROSS THE WESTERN HIGH PLAINS FLANKED BY HIGH PRESSURE
REACHING FROM THE EASTERN DAKOTAS TO KS. OVER THE LOCAL AREA...A
LIGHT N-NE 925 MB AND 850 MB FLOW CONTINUED TO FEED MOISTURE FROM
THE GREAT LAKES...AND DEPARTING STORM SYSTEM INTO ESPECIALLY THE IL
SIDE OF THE FORECAST AREA. THIS TRAJECTORY SHOULD FINALLY BREAK DOWN
TODAY AS THE WESTERN U.S. UPPER RIDGE BUILDS AND EDGES EASTWARD...
PUSHING THE SURFACE RIDGE...AND A WEAK MID LEVEL ANTICYCLONE OVER
SOUTHERN LAKE MI EASTWARD.
&&
.SHORT TERM...TODAY AND TONIGHT...
MAIN CHALLENGES ARE CENTERED ON CLOUD AND TEMPERATURE TRENDS. SHORT
TERM MODELS GENERALLY DEPICT THE MOISTURE LAYER AROUND 925 MB
ASSOCIATED WITH THE STRATUS DECK...THAT WAS COVERING MUCH OF WESTERN
AND SOUTHERN IA...SHIFTING SOUTHWARD TODAY. EAST OF THE MS
RIVER...THE EXTENSIVE STRATUS DECK IS SHOWN MAKING A WESTWARD
RESURGENCE IN THE AFTERNOON AFTER CLEARING THIS MORNING. THIS IS
MOST PRONOUNCED IN THE LATEST RAP RH FIELDS. FOR NOW...WILL KEEP A
MORE OPTIMISTIC FORECAST OF MOSTLY SUNNY SKIES OVER THE ENTIRE AREA
BY AFTERNOON...COUNTING ON THE EFFECTS OF INCREASING MID LEVEL
SUBSIDENCE WITH THE INCOMING UPPER LEVEL RIDGE. EVEN WITH
SUNSHINE...LOOKING AT HIGHS FROM UPSTREAM YESTERDAY AND CONSIDERING
925 MB TEMPERATURES THAT WILL BE SIMILAR TO YESTERDAY...HIGHS FROM
THE UPPER 20S NORTH TO LOWER 30S LOOK REASONABLE.
TONIGHT...THE SURFACE RIDGE TO THE WEST WEAKENS AS IT PASSES THROUGH
THE AREA ALLOWING WINDS TO BECOME LIGHT AND VARIABLE TOWARD MORNING.
SKIES SHOULD INITIALLY BE MOSTLY CLEAR...BUT THERE WILL BE A THREAT
OF INCREASING HIGH CLOUDS IN THE NW FLOW ALOFT. THIS WOULD PREVENT
TEMPERATURES FROM BOTTOMING OUT OVER OUR EXTENSIVE SNOWFIELD AND
FOR NOW WILL COUNT ON THIS OCCURRING TO HOLD MINS NO LOWER THAN
AROUND 10 NORTH TO THE MID TEENS SOUTH. IF HIGH CLOUDS DO NOT
MATERIALIZE...WIDESPREAD SINGLE DIGITS WOULD BE LIKELY...SIMILAR
TO WHAT IS OCCURRING THIS MORNING.
SHEETS
.LONG TERM...SUNDAY THROUGH FRIDAY...
SUNDAY NIGHT THROUGH TUESDAY...THE NEXT SYSTEM TO AFFECT THE UPPER
MISSISSIPPI VALLEY WILL OCCUR SUNDAY NIGHT THROUGH TUESDAY. MODEL
FORECASTS ARE INCONSISTENT WITH LARGE DIFFERENCES NOTED IN THE
PLACEMENT OF THE UPPER LOW. 06Z SATURDAY WATER VAPOR SATELLITE
IMAGERY SHOWS THE SYSTEM IS CURRENTLY OVER THE GULF OF ALASKA. MODEL
SOLUTIONS WILL LIKELY CONTINUE TO BE INCONSISTENT UNTIL THE WAVE
MOVES ONSHORE AND GETS BETTER SAMPLED BY THE UPPER AIR NETWORK. AT
12Z MONDAY ALL MODELS SHOW THE UPPER LOW OVER MONTANA BUT LARGE
DIFFERENCE IN PLACEMENT OCCUR AFTER THAT. BY 18Z TUESDAY THE NAM
MOVES THE UPPER LOW FROM MONTANA TO SOUTHERN MINNESOTA...THE
ECMWF/DGEX MOVE THE UPPER LOW ACROSS IOWA/ILLINOIS WHILE THE GFS
TAKES THE LOW SOUTH OF THE REGION ACROSS MISSOURI. EVEN WITH THE
UPPER LOW PLACEMENT PROBLEMS...ALL MODELS SHOW AN ELEVATED WARM
ADVECTION WING AHEAD OF THE SYSTEM WHICH WOULD BREAK OUT SNOW ACROSS
THE AREA BEFORE DAYBREAK MONDAY MORNING. FOR NOW I HAVE HAVE KEPT
CURRENT FORECAST CHANCE POPS FOR SUNDAY NIGHT BUT RAISED POPS TO
LIKELY CATEGORY FOR MONDAY MORNING. SNOW WILL CONTINUE INTO TUESDAY
AS UPPER FORCING INCREASES AS THE UPPER LOW MOVES CROSSES OVER OR
NEAR THE REGION.
BOTTOM LINE...CONFIDENCE IS HIGH SNOW WILL FALL IN OR NEAR OUR
FORECAST AREA MONDAY AND TUESDAY. CONFIDENCE IS LOW AS TO SPECIFIC
LOCATION AND TOTAL SNOW AMOUNTS.
WEDNESDAY THROUGH FRIDAY...LATER IN THE WEEK THE UPPER AIR PATTERN
SHIFTS TO A SOUTHWESTERLY FLOW AS AN UPPER LEVEL RIDGE LOCATED OVER
THE ROCKIES BEGINS TO MOVE EAST. SURFACE WINDS WILL BE SOUTHERLY
COMING AROUND THE WEST SIDE OF HIGH PRESSURE LOCATED OVER THE GREAT
LAKES/OHIO VALLEY. TEMPERATURES SHOULD BE CLOSE TO NORMAL THURSDAY
AND COULD EVEN BE ABOVE NORMAL BY FRIDAY. THE END OF NEXT WEEK LOOKS
TO BE DRY. ..KUHL..
&&
.AVIATION...
VFR CONDITIONS EXPECTED TO PERSIST FOR AT LEAST THE NEXT 24 HOURS.
STRATUS WITH VFR CIGS ACROSS SE IA AND NW IL IS EXPECTED TO
GRADUALLY DECREASE THIS MORNING AS HIGH PRESSURE AND LOW LEVEL DRY
AIR CONTINUES BUILDING IN. FEW TO SCATTERED CUMULUS WITH BASES OF
2500-3500 FT AGL MAY ALSO DEVELOP BY LATE MORNING THROUGH MID
AFTERNOON. NORTHERLY WINDS WILL CONTINUE GENERALLY AT 4-11 KTS
THROUGH AFTERNOON...THEN BECOME NEAR CALM BY EVENING AS HIGH
PRESSURE SETTLES OVERHEAD.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SHEETS/KUHL
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1046 PM CST FRI MAR 1 2013
.UPDATE...
ISSUED AT 928 PM CST FRI MAR 1 2013
SEEMINGLY NON-STOP...ALBEIT VERY LIGHT...SNOW CONTINUES TO FALL
OVER THE CWA THIS EVENING...WITH ANOTHER BAND OF 10-20DBZ ECHOES
NOW GROWING FROM THE UIN AREA SOUTH TO NEAR THE I-70 CORRIDOR.
A FEW SPOTS COULD STILL SEE A DUSTING OF SNOW BUT FOR MOST OF THE
AREA THINK THE SNOW WILL BE MORE ALONG THE LINE OF FLURRIES...AND
WILL CONTINUE THEM THROUGHOUT THE NIGHT.
OTHER QUESTION IS IF THERE WILL BE ANY CLEARING OVERNIGHT. IR SATELLITE
PICS INDICATE SOME HOLES HAVE FORMED IN THE CLOUDS OVER E MO...BUT
MORE SIGNIFICANT CLEARING AREA IS WORKING S FROM EASTERN
IOWA...AND 900MB RUC RH FORECASTS SEEM TO HAVE A GOOD HANDLE ON
THIS CLEARING LINE. WILL WORK THIS CLEARING..AND DROP MENTION OF
FLURRIES...INTO OUR FAR N COUNTIES INCLUDING UIN...DURING THE
PREDAWN HOURS. WILL ALSO LOWER TEMPS A FEW DEGREES IN THIS PART
OF THE CWA TO ACCOUNT FOR THIS LATE NIGHT CLEARING.
TRUETT
&&
.SHORT TERM...(THROUGH TONIGHT)
ISSUED AT 213 PM CST FRI MAR 1 2013
FOCUS THRU THE PERIOD WILL BE PRECIP CHANCES.
POPS FOR TONIGHT WILL BE A LAST MIN DECISION BASED ON LATEST RADAR
TRENDS. WITH LITTLE IN THE WAY OF FORCING OR SOMETHING TO TRACK FOR
THE SN TONIGHT...WILL BE DIFFICULT TO PIN DOWN EXACTLY WHAT AREAS
WILL SEE LIGHT SN VERSUS FLURRIES AND NOTHING AT ALL. LATEST MDL
GUIDANCE SUGGESTS BEST CHANCES WILL BE IN FAR SRN PORTIONS OF THE
CWA AND PERHAPS A CONTINUING BAND IN CNTL MO. ELSEWHERE...FLURRIES
MAY PERSIST THRU MUCH OF THE EVENING HOURS. CAN NOT COMPLETELY RULE
OUT FLURRIES CONTINUING AFTER MIDNIGHT...BUT SHUD BE CONFINED TO FAR
SRN PORTIONS OF THE CWA IF THEY OCCUR THAT LATE.
WHILE SOME MDL GUIDANCE SUGGESTS CLOUDS DISSIPATING LATE
TONIGHT...GIVEN EXTENSIVE CLOUD COVER UPSTREAM...BELIEVE THAT CLOUDS
WILL STRUGGLE TO DISSIPATE TONIGHT. HAVE THEREFORE CONTINUED A
PERSISTENCE FORECAST FOR TEMPS TONIGHT.
TILLY
&&
.LONG TERM...(SATURDAY THROUGH NEXT FRIDAY)
ISSUED AT 213 PM CST FRI MAR 1 2013
(SATURDAY THROUGH TUESDAY)
FOCUS EARLY IN THE PERIOD WILL BE TEMPS AS THE SFC RIDGE BUILDS
INTO THE REGION. MDLS ARE GENERALLY IN GOOD AGREEMENT THRU SUN.
AS DISCUSSED ABOVE...EXPECT CLOUD COVER TO LINGER THRU MUCH OF THE
DAY SAT. HAVE THEREFORE TRENDED CLOSE TO PERSISTENCE KEEPING TEMPS
AOB THE COLDEST MOS THRU SAT NIGHT. WITH ONE BATCH OF CLOUDS MOVING
OUT OF THE REGION JUST BEFORE CI ASSOCIATED WITH THE NEXT SYSTEM
MOVES IN...SHUD BE A BRIEF TIME WHERE MUCH OF THE AREA IS CLOUD
FREE. WITH THE SFC RIDGE SETTING OVER THE REGION...GOOD
RADIATIONAL COOLING SHUD OCCUR.
FOCUS QUICKLY TURNS TO THE NEXT APPROACHING SYSTEM. MDL
DIFFERENCES BECOME APPARENT STARTING SUN. THERE ARE TWO BASIC
SOLNS AMONG THE MDLS. THE GFS/ECMWF/GEM IN ONE CAMP WITH THE
NAM/DGEX/LOCAL WRF IN THE OTHER. THE SREF AND GEFS MEAN ALSO TREND
AWAY FROM THE NAM SOLN LATE IN THE PERIOD. HAVE THEREFORE TRENDED
TWD THE GFS/ECMWF/GEM SOLNS. THIS RESULTS IN A WETTER FORECAST
WITH SIMILAR THERMAL PROFILES. GIVEN MDL PERFORMANCE WITH THIS
SYSTEM OVER THE PAST FEW DAYS...STILL HAVE SOMEWHAT LOW CONFIDENCE
IN ANY ONE SOLN.
WHILE THE ECMWF/GEM/GFS ARE IN RELATIVELY GOOD AGREEMENT EARLY IN
THE PERIOD...DIFFERENCES BECOME GREATER BY TUES. THE GFS BECOMES A
FAST AND STRONG OUTLIER WITH THE UPPER LOW. THE GEFS MEAN ALSO
TRENDS SLOWER THAN THE OPERATIONAL SOLN. NOT COMPLETELY SURE WHAT
TO MAKE OF THE ECMWF SOLN WHICH HAS THE UPPER LOW SO FAR DETACHED
FROM THE SFC WAVE. WITH SUPPORT FROM THE GEM...HAVE INCREASED POPS
MON NIGHT AND TUES...BUT KEPT GENERAL RA/SN MIX WORDING FOR PRECIP
TYPE FOR NOW.
(WEDNESDAY THROUGH FRIDAY)
WITH LITTLE TO NO PRECIP ANTICIPATED DURING THIS PERIOD...FOCUS
WILL TURN TO TEMPS ONCE AGAIN.
WHAT DIFFERENCES THERE WERE...MDLS HAVE COME INTO A GENERAL
AGREEMENT THRU THIS PERIOD. WITH THE SFC RIDGE IN PLACE ON
WED...TRENDED TWD COOLER GUIDANCE. WITH THE SFC RIDGE MOVING OUT
OF THE AREA BY THURS AND RIDGING ALOFT...STARTED A QUICK WARMING
TREND THRU THE END OF THE PERIOD.
TILLY
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1037 PM CST FRI MAR 1 2013
FLURRIES AND LIGHT SNOW WILL EVENTUALLY TAPER OFF OVERNIGHT
ALTHOUGH A BRIEF PD OF MVFR VSBYS WILL BE POSSIBLE IF AN ENHANCED
POCKET OF LIGHT SNOW MOVES DIRECTLY OVER ONE OF THE TAF SITES.
SPATIAL COVERAGE OF MVFR CIGS VARIED WIDELY AT TAF ISSUANCE
HOWEVER THERE WAS ALSO A CLEARING LINE APPROACHING FROM THE NORTH
WHICH WAS ASSOCIATED WITH THE ARRIVAL OF DRIER AIR. ATTM IT
APPEARS THAT THE BACK EDGE OF THE STRATOCU WILL REACH THE
TERMINALS TOMORROW MORNING ALTHOUGH IT IS POSSIBLE THAT THE
LINGERING SNOW COVER OVER NRN MO MAY SLOW DOWN ITS ARRIVAL.
SPECIFICS FOR KSTL...FLURRIES AND LIGHT SNOW WILL EVENTUALLY TAPER
OFF OVERNIGHT ALTHOUGH A BRIEF PD OF MVFR VSBYS WILL BE POSSIBLE
IF AN ENHANCED POCKET OF LIGHT SNOW MOVES DIRECTLY OVER THE
TERMINAL. CIGS SHOULD IMPROVE ONCE DRIER AIR WORKS INTO THE REGION
FROM THE NORTH. ATTM IT APPEARS THAT THE CLEARING LINE WILL REACH
KSTL LATE TOMORROW MORNING.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1216 AM CST SAT MAR 2 2013
.UPDATE...
ISSUED AT 836 PM CST
A FAIRLY SHARP REDUCTION IN SKY COVER...ESPECIALLY
THROUGH MIDNIGHT. 11-3.9 MICRON SATELLITE IMAGERY REVEALS NEARLY
CLOUD- FREE SKIES OVER MOST OF THE CWA AT THIS HOUR...WITH A
FAIRLY SOLID LOW STRATUS DECK HOLDING JUST OFF TO OUR EAST...AND A
FAIR AMOUNT OF MID-HIGH LEVEL CLOUDS STILL FOCUSED OVER WESTERN
NEBRASKA...ALTHOUGH THESE WILL GRADUALLY BE INVADING THE CWA AS
THE NIGHT WEARS ON. THE JURY IS STILL OUT ON THE FINE DETAILS
REGARDING THE TIMING AND SEVERITY OF FOG TONIGHT...BUT DESPITE
MODELS SUCH AS THE 01Z RAP LARGELY DOWNPLAYING WIDESPREAD
VISIBILITY RESTRICTIONS...HAVE MADE NO CHANGES TO THE PREVIOUS
FORECAST AS THE SYNOPTIC SETUP OF CLEAR SKIES/LIGHT AND VARIABLE
BREEZES CERTAINLY IS SUPPORTIVE OF SOME DEGREE OF FOG. HAVE ALSO
MADE NO CHANGES TO LOW TEMPS...WITH MOST OF THE CWA STILL ON TRACK
TO BOTTOM OUT SOMEWHERE BETWEEN 13-19 DEGREES.
&&
.SHORT TERM...TONIGHT AND TOMORROW. MAIN FORECAST CONCERNS LIE
WITH FOG POTENTIAL TONIGHT AND TEMPERATURES TOMORROW.
SAW A FEW FLURRIES AFFECT PRIMARILY THE WRN AND ERN FRINGES OF THE
CWA EARLIER THIS MORNING...BUT THE AFTERNOON HAS BEEN QUIET. THE
LOW LEVEL STRATUS HAS REMAINED STUBBORN FOR MOST OF THE AREA...BUT
THERE ARE PEAKS OF SUN OUT THERE. AT THE SURFACE...A RIDGE OF HIGH
PRESSURE EXTENDS FROM CENTRAL CANADA DOWN TO THE SRN
PLAINS...KEEPING WINDS NORTH/NORTHWESTERLY...AND GUSTY AT
TIMES...ESP IN AREAS THAT HAVE BEEN ABLE TO SEE A BIT OF SUN.
LOOKING TO THIS EVENING/OVERNIGHT...DRY CONDITIONS WILL CONTINUE
WITH SHARP UPPER LEVEL NORTHWESTERLY FLOW IN PLACE. EXPECTING CLOUD
COVER TO BE VARIABLE...AND AM INSERTING A FOG MENTION INTO THE
FORECAST. MODELS ARE IN GOOD AGREEMENT SHOWING THE SFC RIDGE AXIS
SLIDING EAST INTO AND THROUGH THE CWA OVERNIGHT...DROPPING WINDS
DOWN TO LIGHT/VARIABLE. EXPECTING FOG TO DEVELOP LATE THIS EVENING
AS TEMPERATURES COOL AND WINDS FALL OFF...WHICH SHOULD LINGER INTO
THE MID MORNING HOURS ON SATURDAY. OVERNIGHT LOWS LOOKING TO FALL
INTO THE MID/UPPER TEENS.
INTO TOMORROW...DRY CONDITIONS CONTINUE...WITH MODELS IN GOOD
AGREEMENT SHOWING THE UPPER LEVEL RIDGE IN PLACE OVER THE ROCKIES
GRADUALLY SLIDING TO THE EAST. AS THE SFC RIDGE AXIS CONTINUES TO
SLIDE EAST...A TROUGH OF LOW PRESSURE DEVELOPS ALONG THE HIGH
PLAINS...BRINGING A MORE SOUTHWEST TO WESTERLY COMPONENT TO THE
WINDS...THOUGH WIND SPEEDS LOOK TO ONLY TOP OUT ARND 10 MPH.
WARMER AIR ALOFT STARTS TO BUILD IN FROM THE WEST...BUT MODEL
SOUNDINGS SHOWING THINGS NOT MIXING OVERLY WELL...SO IT WILL BE
TOUGH TO FULLY TAP INTO THAT WARMER AIR. AS A RESULT WAS HESITANT
TO RAISE FORECAST HIGHS...BUT IT SHOULD STILL BE WARMER THAN
TODAY...ESP IN THE WEST. CURRENT FORECAST CALLS FOR MID 30S IN THE
EAST TO THE LOWER/MID 40S IN THE WEST.
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY. BEGINNING SATURDAY
NIGHT...AN UPPER LEVEL RIDGE OF HIGH PRESSURE OVER THE ROCKIES
WILL BEGIN TO BREAK DOWN/SHIFT EAST AS AN UPSTREAM TROUGH
TRANSLATES SOUTHEAST FM BRITISH COLUMBIA. A MILD AIRMASS WILL
EXPAND EASTWARD ONTO THE CENTRAL PLAINS BY SUNDAY WITH H85 TEMPS
CLIMBING TO NEAR 10C. FORECAST SOUNDING HOWEVER INDICATE VERY
LITTLE MIXING...AND ALTHOUGH WE ARE LOOKING AT A WARMER DAY WITH
THE WARM AIRMASS IN PLACE AHEAD OF AN APPROACHING COLD
FRONT...WILL KEEP TEMPS IN THE UPPER 40S/MID 50S DUE TO LACK OF
GOOD MIXING. WILL NEED TO MONITOR OUR EASTERN ZONES FOR LINGERING
LOW CLOUD COVER AS WELL...MORE SO INDICATED BY GFS...AS LOW CLOUDS
WOULD IMPACT TEMPS.
SUNDAY NIGHT...THE UPPER TROUGH TRANSLATES INTO THE WESTERN
DAKOTAS WITH THE ASSOCIATED COLD FRONTAL BOUNDARY SWEEPING
SOUTHEAST OVERNIGHT. GOOD MID LEVEL FRONTOGENESIS IS PROGGED
BETWEEN H85 AND H7 AFTER 06Z...AND WOULD NOT BE SURPRISED TO SEE
SOME SPRINKLES/BRIEF SHOWER. FORECAST SOUNDINGS INDICATE DENDRITIC
MOISTURE IS LACKING...AND WITH TEMPS NEAR/BELOW FREEZING AM
HESITANT TO INCLUDE FREEZING PCPN POTENTIAL AND WILL LEAVE FCST
DRY FOR NOW AND MONITOR TRENDS GIVEN THIS LOOKS LIKE MAINLY TRACE
AMNTS OF PCPN. WINDS SHIFT NW FOLLOWING FROPA WITH 6HR PRESSURE
RISES PROGGED NEAR 8MB. WINDY CONDITIONS WILL DEVELOP MONDAY IN A
TIGHT PRESSURE GRADIENT AS THE LOW MOVES INTO SOUTHERN MN.
FORECAST SOUNDINGS ON MONDAY SUGGEST MIXING NEAR H8 WITH WINDS AT
THE TOP OF THE LAYER PROGGED AROUND 45KTS. MONDAY LOOKS TO FEATURE
WINDY/COOLER CONDITIONS AND WILL NEED TO WATCH FOR POTENTIAL WIND
ADV.
PCPN CHCS MONDAY/MONDAY NIGHT WILL BE DEPENDENT UPON THE TRACK OF
THE UPPER LOW CROSSING THE PLAINS WITH THE NAM/ECMWF/GFS
ENSEMBLE FAVORING A FARTHER NORTH TRACK THAN THE GFS/GEM. FCST IS
BASED ON THE FARTHER NORTH TRACK OF SYSTEM IN LINE WITH NAM/EC/GEM
WITH SLIGHT CHCS/BUFFER POPS IN OUR NORTHERN/EASTERN ZONES ON THE
BACK SIDE OF THE LOW...AND IF NORTHERN TREND CONTINUES...MAY NOT
NEED POPS AT ALL IN DRY SLOT.
TUESDAY SHLD BE THE COLDEST OF THE WORKWEEK IN THE COLD AIRMASS
BEHIND THE SYSTEM AS A 1035MB SURFACE HIGH BUILDS SOUTH ONTO THE
PLAINS. TEMPS BEGIN TO RECOVER ON WEDNESDAY AS SFC RIDGE AXIS
SHIFTS EAST AND HEIGHTS RISE BEHIND THE DEPARTING LOW. THE PATTERN
ALOFT TRANSITIONS SOUTHWESTERLY BY THE END OF THE WORKWEEK AHEAD
OF AN UPPER TROUGH DEEPENING ALONG THE WEST COAST/SOUTHWEST CONUS.
WARM FRONTAL BOUNDARY LIFTS NORTHWARD WITH TEMPS EXPECTED TO TOP
OUT WELL INTO THE 40S/50S FOR THE LATTER PART OF THE WORKWEEK.
&&
.AVIATION...(FOR THE 06Z KGRI TAF THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1216 AM CST SAT MAR 2 2013
ALTHOUGH EXPECT PREVAILING VFR CONDITIONS THROUGH THE MAJORITY OF
THE PERIOD...CONFIDENCE ESPECIALLY REGARDING VISIBILITY TRENDS
OVER THE NEXT 6-9 HOURS IS ADMITTEDLY SHAKY. AT LEAST SO FAR
TONIGHT...EARLIER INDICATIONS OF FAIRLY WIDESPREAD IFR TO LIFR
VISIBILITY/CEILING IN FOG HAS NOT COME TO FRUITION...AND CONSENSUS
OF LATEST MODELS SUGGESTS THAT KGRI MAY REMAIN JUST FAR ENOUGH
EAST TO AVOID A MAJOR DEGRADATION IN CONDITIONS. THAT BEING
SAID...GIVEN GENERALLY LIGHT/VARIABLE BREEZES WILL AT LEAST
MAINTAIN SEVERAL HOURS OF MVFR VISIBILITY POTENTIAL...AND AMEND
SHORT TERM TRENDS AS NEEDED. ASSUMING MAJOR FOG PROBLEMS DO NOT
ARISE...EXPECT ANY CEILINGS TO REMAIN VFR THROUGH THE
PERIOD...ALTHOUGH A BROKEN VFR DECK BELOW 10 THOUSAND FEET IS
POSSIBLE FOR PART OF THE DAY. ALTHOUGH SOME MODELS ARE ALREADY
INDICATING ADDITIONAL POTENTIAL FOR FOG TOWARD THE END OF THE
PERIOD MAINLY AFTER 03Z SATURDAY EVENING...CONFIDENCE IS NOT HIGH
IN THIS SCENARIO GIVEN SHAKY MODEL PERFORMANCE IN THE
NEAR-TERM...SO WILL DEFER TO LATER FORECASTS TO POSSIBLY INSERT
SATURDAY NIGHT FOG. SURFACE WINDS WILL NOT BE MUCH OF AN ISSUE
DURING THE PERIOD...WITH SOUTH-SOUTHWEST SPEEDS ONLY TOPPING OUT
AROUND 10KT DURING THE AFTERNOON INTO SATURDAY EVENING.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...PFANNKUCH
SHORT TERM...ADO
LONG TERM...FAY
AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
358 AM EST SAT MAR 2 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL CROSS THE REGION FROM THE WEST
TODAY. LOW PRESSURE WILL MOVE OFF THE EAST COAST ON SUNDAY...WITH A
RETURN OF BRIEF HIGH PRESSURE THROUGH MONDAY. A LOW PRESSURE SYSTEM
DEVELOPING OVER THE MID MISSISSIPPI RIVER VALLEY ON TUESDAY WILL
CROSS THE AREA ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 345 AM...LATEST IR SATELLITE INDICATES COLD TOP CLOUDS
RAPIDLY EXPANDING ACROSS THE SOUTHERN AND CENTRAL NC MTNS...WITH A
BAND OF -22C OR COLDER CLOUDS ACROSS EXTREME NE GA AND THE SC
MTNS. RADAR RETURNS HAVE INCREASED EARLY THIS MORNING...ESPECIALLY
ACROSS NE GA...SC MTNS...AND THE CENTRAL MOUNTAINS...WITH SEVERAL
AREAS OF DBZ AROUND 30 DBZ. DUAL POL PRODUCTS INDICATE THAT THE
MELTING LAYER HAS LOWERED TO AROUND 1 KFT. BASED ON THE LATEST
TRENDS...I WILL ADD THE CENTRAL NC MTNS FROM MACON TO
TRANSYLVANIA...EXTREME NE GA FROM FRANKLIN TO RABUN...AND OCONEE
AND PICKENS MTNS TO THE WINTER WEATHER ADVISORY UNTIL 6 PM.
SHOWERS ARE FORECAST TO SPREAD SLOWLY EAST ACROSS THE FOOTHILLS AND
PIEDMONT THIS MORNING. THE EASTWARD MOVEMENT OF THE PRECIPITATION
WILL BE A RESULT OF THE SPREADING OF H5 15 TO 20 MB/HR VERTICAL
VELOCITIES ALONG AND AHEAD OF THE CLOSED LOW. THE SYNOPTIC SCALE
FORCING SHOULD PEAK AROUND 12Z...THEN GRADUALLY WEAKENING THROUGH
THE REST OF THE DAYLIGHT HOURS. FORECAST SOUNDINGS ACROSS THE
FOOTHILLS AND PIEDMONT...INCLUDING PARTIAL THICKNESSES...SHOULD
SUPPORT SN ACROSS THE MTNS...RASN ACROSS THE FOOTHILLS...WITH RA
ACROSS THE PIEDMONT. HOWEVER...STRONGER SHOWERS SHOULD RESULT IN
PURE SN THIS MORNING...EVEN OVER THE PIEDMONT. BASED ON A BLEND OF
HPC...WRFARW...AND RUC QPF...I WILL FORECAST 2-3 INCHES ACROSS THE
TN BORDER CO...AND THE SOUTHERN AND CENTRAL MTNS...WITH 4 INCHES
POSSIBLE IN SPOTS ALONG THE RIDGELINE OF THE SMOKIES. EXTREME NE GA
MAY SEE 0.5 TO 1.4 INCHES...WITH ACROSS AN INCH ACROSS OCONEE AND
PICKENS MTNS. AREAS EAST...INCLUDING THE GSP AND CLT METRO AREAS MAY
SEE AROUND 0.1-0.2 INCHES. HIGH TEMPERATURES ARE FORECAST TO RANGE
FROM THE 30S ACROSS THE MTNS TO THE LOW TO MID 40S EAST.
LATE THIS AFTERNOON...SREF INDICATES THAT MUCAPE WILL LIKELY POOL TO
AT LEAST 50 J/KG ACROSS THE FOOTHILLS AND PIEDMONT. AS THE H5 TROF
AXIS PIVOTS EAST OF THE MTNS. WEAKLY CONVECTIVE SHOWERS ARE EXPECTED
TO DEVELOP ACROSS THE FOOTHILLS. CONVECTIVE ALLOWING GUIDANCE
INDICATES THAT THE SHOWERS MAINLY ORGANIZE INTO A LINE OR A CLUSTER.
I WILL TIME THE CONVECTION EAST ACROSS THE EASTERN HALF OF THE
FORECAST AREA THIS AFTERNOON...REACHING KGSP AT 19Z...AND CLT BY 22Z.
TONIGHT...NWFS WILL GRADUALLY FADE ALONG THE TN BORDER THIS
EVENING...ENDING DURING THE LATE NIGHT HOURS. WINDS WILL REMAIN FROM
THE NW...RANGING FROM 5 TO 10 KTS. CLOUD COVER WILL DECREASE THROUGH
THE NIGHT...ESPECIALLY EAST OF THE MTNS. LOW TEMPERATURES SHOULD
RANGE FROM THE L20S ACROSS THE MTNS TO THE MID TO U20S EAST.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM SATURDAY...ONE FINAL SHORTWAVE WILL DROP INTO THE EAST
COAST TROUGH AXIS ON SUNDAY BEFORE IT DEPARTS...BRINGING MAINLY
CHANNELED VORTICITY FROM THE WRN GREAT LAKES TO THE WRN CAROLINAS.
DEEP LAYER MOISTURE WILL BE ABSENT WITH THIS FEATURE...BUT LINGERING
LOW LEVEL NW UPSLOPE FLOW MOISTURE MAY PERMIT ISOLATED SNOW SHOWERS
TO LINGER ALONG THE TN BORDER INTO THE MORNING HOURS BEFORE DRYING
UP. CHILLY THICKNESSES...AND LINGERING PATCHY MID AND HIGH
CLOUDS...WILL KEEP TEMPERATURES SEVERAL CATEGORIES BELOW NORMAL.
A FLAT UPPER RIDGE WILL CROSS THE AREA MONDAY THROUGH MONDAY NIGHT.
PLENTY OF HIGH LEVEL CLOUDS SHOULD TOP THE RIDGE AXIS IN THE SWIFT
WESTERLY FLOW ALOFT DURING THIS PERIOD. THE AIRMASS SHOULD MODIFY
ENOUGH TO PUSH MAX TEMPERATURES BACK INTO THE 50S THROUGHOUT MON
AFTN...EXCEPT 40S ALONG THE HIGHER MOUNTAINS.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 310 AM SATURDAY...THERE IS GENERALLY GOOD CONSENSUS AMONG THE
VARIOUS MODELS ON A DEEPENING LOW PRES SYSTEM MOVING SE THROUGH THE
MIDWEST ON TUE...CROSSING THE FORECAST AREA ON WED...THEN DEEPENING
FURTHER ALONG THE IMMEDIATE E COAST WED NIGHT. HOWEVER...DIFFERENCES
AMONG THE MODELS IN THE SFC LOW AND 850 MB LOW CENTER TRACKS WILL
PLAY A CRITICAL ROLE IN PRECIPITATION TYPE AND AMOUNT. THERE IS GOOD
AGREEMENT THAT ISENTROPIC LIFT AHEAD OF THE SYSTEM WILL RETURN TO
THE REGION LATE MON NIGHT...WITH THE BEST BELT OF UPGLIDE ACROSS THE
HEART OF THE AREA MIDDAY TUE. PROFILES SUPPORT MAINLY RAIN ON THE
WARM ADVECTION SIDE OF THE SYSTEM...BUT WITH FREEZING RAIN POSSIBLE
IN SPOTS AT ONSET...ESPECIALLY ACROSS THE NRN NC MOUNTAINS.
THICKNESSES SHOULD CRASH WED MORNING AS THE COLD LOW PRESSURE SYSTEM
TRANSITIONS TOWARD THE COAST. QG FORCING SHOULD BE PLENTIFUL JUST
AHEAD OF THE LOW TUE NIGHT AND WED MORNING...WITH SOME DEGREE OF
FRONTOGENESIS AND DEFORMATION ZONE FORCING TRAILING THE DEPARTING
LOW THROUGH THE PIEDMONT WED AFTN/EVENING. VERY STEEP LAPSE RATES
UNDER THE PASSING UPPER LOW SHOULD SUPPORT AT LEAST ISOLD TO SCT
THUNDERSTORMS/THUNDERSNOW AT TIMES. CONFIDENCE IS HIGHEST ON
SIGNIFICANT ACCUMULATING SNOW OVER THE MTNS AND ALSO NC FOOTHILL AND
PIEDMONT LOCATIONS ALONG AND NORTH OF INTERSTATE 40. MORE OF A
RAIN/SNOW MIX IS EXPECTED TOWARD THE INTERSTATE 85 CORRIDOR AND
POINTS SOUTH...BUT LIKELY ENDING AS SNOW SHOWERS. WILL CONTINUE THE
HWO MENTION FOR THIS POTENTIALLY SIGNIFICANT WINTER STORM SYSTEM.
A WARMER AND DRY RIDGE PATTERN WILL RETURN THU THROUGH FRI...WITH
TEMPERATURES SLOWLY REBOUNDING TO WITHIN 5 DEGREES OF NORMAL.
&&
.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...THE 6Z TAF WILL BEGIN WITH VFR CONDITIONS AND A LIGHT NW
WIND. CEILING BASES SHOULD GRADUALLY LOWER THROUGH THE PRE DAWN
HOURS AS SYNOPTIC SCALE FORCING SPREADS ACROSS THE PIEDMONT. BY
12Z...MID LEVEL FORCING SHOULD PEAK ACROSS THE TERMINAL...THEN
WEAKENING THROUGH THE AFTERNOON HOURS. NAM FORECAST SOUNDINGS
SUPPORTS CEILINGS FALLING TO AT LEAST MVFR BY 12Z...THEN LIFTING
ABOVE 030 BY 22Z. THE ARRIVAL OF THE DEEP FORCING AT DAY BREAK MAY
YIELD ONE OF THE HIGHEST CHCS FOR PRECIP DURING THE PERIOD. I WILL
HIGHLIGHT -SHSN BETWEEN 12Z TO 15Z. ANOTHER BAND OF RASN MAY PASS
ACROSS THE TERMINAL BETWEEN 22Z TO 24Z WITH THE PUSH OF THE DRY
SLOT. ONCE THE DRY SLOT ARRIVES...CEILINGS WILL LIFT AND STEADY NW
WINDS SHOULD REMAIN THROUGH 12Z SUN. I WOULD EXPECT THAT
ACCUMULATING SNOW IS POSSIBLE THIS MORNING AND AGAIN LATE THIS
AFTERNOON...ACCUMS WILL LIKELY REMAIN LESS THAN A HALF INCH.
ELSEWHERE...TIMING SIMILAR TO CLT. HOWEVER...KGSP...KGMU...AND KHKY
SHOULD SEE MVFR CEILINGS DEVELOP AROUND 11Z...BUT DOWNSLOPE FLOW
SHOULD SUPPORT VFR BY MID MORNING. ALL AREAS WILL SEE THE POTENTIAL
FOR LIGHT ACCUMULATING SNOW THIS MORNING....BEST CHC BETWEEN 12Z TO
16Z. HOWEVER...THE FORMATION OF A WEAKLY CONVECTIVE BAND THIS
AFTERNOON WILL NEED CLOSE ATTENTION.
OUTLOOK...SNOW SHOWERS WILL DIMINSIHING THE TENNESSEE BORDER ON
SUNDAY. MONDAY SHOULD REMAIN VFR ACROSS THE FORECAST AREA.
ANOTHER LOW PRESSURE SYSTEM WILL SPREAD LLVL MOISTURE AND
PRECIPITATION ACROSS THE REGION TUESDAY AND WEDNESDAY MORNING.
CONFIDENCE TABLE...
09-15Z 15-21Z 21-03Z 03-09Z
KCLT HIGH 86% HIGH 80% HIGH 94% HIGH 100%
KGSP HIGH 83% HIGH 95% HIGH 94% HIGH 100%
KAVL HIGH 84% HIGH 97% HIGH 100% HIGH 90%
KHKY HIGH 84% HIGH 91% HIGH 100% HIGH 100%
KGMU HIGH 81% MED 68% HIGH 95% HIGH 100%
KAND HIGH 87% MED 78% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR GAZ010-
017-018-026.
NC...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ033-
048>052-058-059-062>064.
SC...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR SCZ001-
002-004.
&&
$$
SYNOPSIS...HG
NEAR TERM...NED
SHORT TERM...HG
LONG TERM...HG
AVIATION...NED
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
350 AM EST SAT MAR 2 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL CROSS THE REGION FROM THE WEST
TODAY. LOW PRESSURE WILL MOVE OFF THE EAST COAST ON SUNDAY...WITH A
RETURN OF BRIEF HIGH PRESSURE THROUGH MONDAY. A LOW PRESSURE SYSTEM
DEVELOPING OVER THE MID MISSISSIPPI RIVER VALLEY ON TUESDAY WILL
CROSS THE AREA ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 330 AM...LATEST IR SATELLITE INDICATES COLD TOP CLOUDS RAPIDLY
EXPANDING ACROSS THE SOUTHERN AND CENTRAL NC MTNS...WITH A BAND OF
-22C OR COLDER CLOUDS ACROSS EXTREME NE GA AND THE SC MTNS. RADAR
RETURNS HAVE INCREASED EARLY THIS MORNING...ESPECIALLY ACROSS NE
GA...SC MTNS...AND THE CENTRAL MOUNTAINS...WITH SEVERAL AREAS OF DBZ
AROUND 30 DBZ. DUAL POL PRODUCTS INDICATE THAT THE MELTING LAYER HAS
LOWERED TO AROUND 1 KFT. BASED ON THE LATEST TRENDS...I WILL ADD THE
CENTRAL NC MTNS FROM MACON TO TRANSYLVANIA...EXTREME NE GA FROM
FRANKLIN TO RABUN...AND OCONEE AND PICKENS MTNS TO THE WINTER
WEATHER ADVISORY UNTIL 6 PM.
SHOWERS ARE FORECAST TO SPREAD SLOWLY EAST ACROSS THE FOOTHILLS AND
PIEDMONT THIS MORNING. THE EASTWARD MOVEMENT OF THE PRECIPITATION
WILL BE A RESULT OF THE SPREADING OF H5 15 TO 20 MB/HR VERTICAL
VELOCITIES ALONG AND AHEAD OF THE CLOSED LOW. THE SYNOPTIC SCALE
FORCING SHOULD PEAK AROUND 12Z...THEN GRADUALLY WEAKENING THROUGH
THE REST OF THE DAYLIGHT HOURS. FORECAST SOUNDINGS ACROSS THE
FOOTHILLS AND PIEDMONT...INCLUDING PARTIAL THICKNESSES...SHOULD
SUPPORT SN ACROSS THE MTNS...RASN ACROSS THE FOOTHILLS...WITH RA
ACROSS THE PIEDMONT. HOWEVER...STRONGER SHOWERS SHOULD RESULT IN
PURE SN THIS MORNING...EVEN OVER THE PIEDMONT. BASED ON A BLEND OF
HPC...WRFARW...AND RUC QPF...I WILL FORECAST 2-3 INCHES ACROSS THE
TN BORDER CO...AND THE SOUTHERN AND CENTRAL MTNS...WITH 4 INCHES
POSSIBLE IN SPOTS ALONG THE RIDGELINE OF THE SMOKIES. EXTREME NE GA
MAY SEE 0.5 TO 1.4 INCHES...WITH ACROSS AN INCH ACROSS OCONEE AND
PICKENS MTNS. AREAS EAST...INCLUDING THE GSP AND CLT METRO AREAS MAY
SEE AROUND 0.1-0.2 INCHES. HIGH TEMPERATURES ARE FORECAST TO RANGE
FROM THE 30S ACROSS THE MTNS TO THE LOW TO MID 40S EAST.
TONIGHT...NWFS WILL GRADUALLY FADE ALONG THE TN BORDER THIS
EVENING...ENDING DURING THE LATE NIGHT HOURS. WINDS WILL REMAIN FROM
THE NW...RANGING FROM 5 TO 10 KTS. CLOUD COVER WILL DECREASE THROUGH
THE NIGHT...ESPECIALLY EAST OF THE MTNS. LOW TEMPERATURES SHOULD
RANGE FROM THE L20S ACROSS THE MTNS TO THE MID TO U20S EAST.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM SATURDAY...ONE FINAL SHORTWAVE WILL DROP INTO THE EAST
COAST TROUGH AXIS ON SUNDAY BEFORE IT DEPARTS...BRINGING MAINLY
CHANNELED VORTICITY FROM THE WRN GREAT LAKES TO THE WRN CAROLINAS.
DEEP LAYER MOISTURE WILL BE ABSENT WITH THIS FEATURE...BUT LINGERING
LOW LEVEL NW UPSLOPE FLOW MOISTURE MAY PERMIT ISOLATED SNOW SHOWERS
TO LINGER ALONG THE TN BORDER INTO THE MORNING HOURS BEFORE DRYING
UP. CHILLY THICKNESSES...AND LINGERING PATCHY MID AND HIGH
CLOUDS...WILL KEEP TEMPERATURES SEVERAL CATEGORIES BELOW NORMAL.
A FLAT UPPER RIDGE WILL CROSS THE AREA MONDAY THROUGH MONDAY NIGHT.
PLENTY OF HIGH LEVEL CLOUDS SHOULD TOP THE RIDGE AXIS IN THE SWIFT
WESTERLY FLOW ALOFT DURING THIS PERIOD. THE AIRMASS SHOULD MODIFY
ENOUGH TO PUSH MAX TEMPERATURES BACK INTO THE 50S THROUGHOUT MON
AFTN...EXCEPT 40S ALONG THE HIGHER MOUNTAINS.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 310 AM SATURDAY...THERE IS GENERALLY GOOD CONSENSUS AMONG THE
VARIOUS MODELS ON A DEEPENING LOW PRES SYSTEM MOVING SE THROUGH THE
MIDWEST ON TUE...CROSSING THE FORECAST AREA ON WED...THEN DEEPENING
FURTHER ALONG THE IMMEDIATE E COAST WED NIGHT. HOWEVER...DIFFERENCES
AMONG THE MODELS IN THE SFC LOW AND 850 MB LOW CENTER TRACKS WILL
PLAY A CRITICAL ROLE IN PRECIPITATION TYPE AND AMOUNT. THERE IS GOOD
AGREEMENT THAT ISENTROPIC LIFT AHEAD OF THE SYSTEM WILL RETURN TO
THE REGION LATE MON NIGHT...WITH THE BEST BELT OF UPGLIDE ACROSS THE
HEART OF THE AREA MIDDAY TUE. PROFILES SUPPORT MAINLY RAIN ON THE
WARM ADVECTION SIDE OF THE SYSTEM...BUT WITH FREEZING RAIN POSSIBLE
IN SPOTS AT ONSET...ESPECIALLY ACROSS THE NRN NC MOUNTAINS.
THICKNESSES SHOULD CRASH WED MORNING AS THE COLD LOW PRESSURE SYSTEM
TRANSITIONS TOWARD THE COAST. QG FORCING SHOULD BE PLENTIFUL JUST
AHEAD OF THE LOW TUE NIGHT AND WED MORNING...WITH SOME DEGREE OF
FRONTOGENESIS AND DEFORMATION ZONE FORCING TRAILING THE DEPARTING
LOW THROUGH THE PIEDMONT WED AFTN/EVENING. VERY STEEP LAPSE RATES
UNDER THE PASSING UPPER LOW SHOULD SUPPORT AT LEAST ISOLD TO SCT
THUNDERSTORMS/THUNDERSNOW AT TIMES. CONFIDENCE IS HIGHEST ON
SIGNIFICANT ACCUMULATING SNOW OVER THE MTNS AND ALSO NC FOOTHILL AND
PIEDMONT LOCATIONS ALONG AND NORTH OF INTERSTATE 40. MORE OF A
RAIN/SNOW MIX IS EXPECTED TOWARD THE INTERSTATE 85 CORRIDOR AND
POINTS SOUTH...BUT LIKELY ENDING AS SNOW SHOWERS. WILL CONTINUE THE
HWO MENTION FOR THIS POTENTIALLY SIGNIFICANT WINTER STORM SYSTEM.
A WARMER AND DRY RIDGE PATTERN WILL RETURN THU THROUGH FRI...WITH
TEMPERATURES SLOWLY REBOUNDING TO WITHIN 5 DEGREES OF NORMAL.
&&
.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...THE 6Z TAF WILL BEGIN WITH VFR CONDITIONS AND A LIGHT NW
WIND. CEILING BASES SHOULD GRADUALLY LOWER THROUGH THE PRE DAWN
HOURS AS SYNOPTIC SCALE FORCING SPREADS ACROSS THE PIEDMONT. BY
12Z...MID LEVEL FORCING SHOULD PEAK ACROSS THE TERMINAL...THEN
WEAKENING THROUGH THE AFTERNOON HOURS. NAM FORECAST SOUNDINGS
SUPPORTS CEILINGS FALLING TO AT LEAST MVFR BY 12Z...THEN LIFTING
ABOVE 030 BY 22Z. THE ARRIVAL OF THE DEEP FORCING AT DAY BREAK MAY
YIELD ONE OF THE HIGHEST CHCS FOR PRECIP DURING THE PERIOD. I WILL
HIGHLIGHT -SHSN BETWEEN 12Z TO 15Z. ANOTHER BAND OF RASN MAY PASS
ACROSS THE TERMINAL BETWEEN 22Z TO 24Z WITH THE PUSH OF THE DRY
SLOT. ONCE THE DRY SLOT ARRIVES...CEILINGS WILL LIFT AND STEADY NW
WINDS SHOULD REMAIN THROUGH 12Z SUN. I WOULD EXPECT THAT
ACCUMULATING SNOW IS POSSIBLE THIS MORNING AND AGAIN LATE THIS
AFTERNOON...ACCUMS WILL LIKELY REMAIN LESS THAN A HALF INCH.
ELSEWHERE...TIMING SIMILAR TO CLT. HOWEVER...KGSP...KGMU...AND KHKY
SHOULD SEE MVFR CEILINGS DEVELOP AROUND 11Z...BUT DOWNSLOPE FLOW
SHOULD SUPPORT VFR BY MID MORNING. ALL AREAS WILL SEE THE POTENTIAL
FOR LIGHT ACCUMULATING SNOW THIS MORNING....BEST CHC BETWEEN 12Z TO
16Z. HOWEVER...THE FORMATION OF A WEAKLY CONVECTIVE BAND THIS
AFTERNOON WILL NEED CLOSE ATTENTION.
OUTLOOK...SNOW SHOWERS WILL DIMINSIHING THE TENNESSEE BORDER ON
SUNDAY. MONDAY SHOULD REMAIN VFR ACROSS THE FORECAST AREA.
ANOTHER LOW PRESSURE SYSTEM WILL SPREAD LLVL MOISTURE AND
PRECIPITATION ACROSS THE REGION TUESDAY AND WEDNESDAY MORNING.
CONFIDENCE TABLE...
09-15Z 15-21Z 21-03Z 03-09Z
KCLT HIGH 86% HIGH 80% HIGH 94% HIGH 100%
KGSP HIGH 83% HIGH 95% HIGH 94% HIGH 100%
KAVL HIGH 84% HIGH 97% HIGH 100% HIGH 90%
KHKY HIGH 84% HIGH 91% HIGH 100% HIGH 100%
KGMU HIGH 81% MED 68% HIGH 95% HIGH 100%
KAND HIGH 87% MED 78% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR GAZ010-
017-018-026.
NC...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ033-
048>052-058-059-062>064.
SC...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR SCZ001-
002-004.
&&
$$
SYNOPSIS...HG
NEAR TERM...NED
SHORT TERM...HG
LONG TERM...HG
AVIATION...NED
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
332 AM CST SAT MAR 2 2013
.SHORT TERM...TODAY THROUGH TUESDAY
332 AM CST SAT MAR 2 2013
UPDATED LAST PARAGRAPH ABOUT THE ACCUMULATING SNOW POTENTIAL FOR
SUNDAY NIGHT THROUGH TUESDAY...MENTIONING THAT WINTER STORM WATCHES
MAY BE REQUIRED.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED RIDGING AGAIN OVER THE WESTERN U.S. AND BEGINNING TO ENTER
THE WESTERN PORTION OF THE PLAINS...WHILE TROUGHING STILL
DOMINATED THE EASTERN U.S. A SHORTWAVE TROUGH WAS EVIDENT OVER THE
FORECAST AREA...PRODUCING SOME CIRRUS AHEAD OF IT OVER EASTERN
WISCONSIN. OTHERWISE...THE AIRMASS HAS DRIED OUT QUITE A
BIT...NOTED BY THE 00Z MPX SOUNDING WITH A PRECIPITABLE WATER OF
0.17 INCHES OR 71 PERCENT OF NORMAL. A LIGHT NORTHERLY BREEZE
CONTINUES AHEAD OF A HIGH PRESSURE RIDGE IN FAR WESTERN MINNESOTA.
THIS BREEZE HAS SO FAR KEPT TEMPERATURES FROM COMPLETELY
PLUMMETING. FARTHER WEST...MID AND HIGH CLOUDS WERE INCREASING
ACROSS THE DAKOTAS AHEAD OF THE BUILDING UPPER RIDGE...IN A
GENERAL WARM ADVECTION PATTERN. NO EVIDENCE YET OF PRECIPITATION
FALLING OUT OF THEM...LIKELY DUE TO THE DRY AIR BETWEEN 600-800MB
ON THE 00Z BIS SOUNDING. AIRMASS AROUND THE NORTHERN PLAINS HAS
WARMED UP SOMEWHAT WITH 850MB TEMPS FROM ABR TO MPX AND GRB AROUND
-8C PER 00Z SOUNDINGS. THE MPX AND GRB OBSERVATIONS WERE ABOUT 2C
WARMER THAN WHAT 01.00Z MODELS FORECASTED. WELL OFF TO THE
WEST...A POTENT UPPER TROUGH WAS LOCATED OVER THE EAST PACIFIC
NEAR 45 N 139 W...WHICH WE ARE WATCHING FOR EARLY NEXT WEEK.
SHORT TERM HIGHLIGHTS / CONCERNS...
1. POTENTIAL FOR SOME LIGHT SNOW LATE TONIGHT/SUNDAY MORNING...
THE AREA OF THICKENING MID/HIGH CLOUDS ACROSS THE DAKOTAS WILL
EVENTUALLY SHIFT OVER THE FORECAST AREA TONIGHT AS THE WESTERN U.S.
RIDGE GETS PUSHED EASTWARD. ACCOMPANYING THE MID/HIGH CLOUDS IS SOME
LOW TO MID LEVEL FRONTOGENESIS AND WEAK ISENTROPIC LIFT ON THE
280-285K SURFACES. THE MAIN QUESTION IS IF ANY SNOW THAT IS PRODUCED
OUT OF THESE CLOUDS AND LIFT CAN MAKE IT TO THE SURFACE. THE 02.00Z
GFS/NAM/ECMWF/CANADIAN ARE ALL DRY...SUGGESTING THAT THE LOW LEVEL
DRY AIR LEFT BEHIND BY THE SURFACE RIDGE CROSSING THE FORECAST AREA
WILL BE ENOUGH TO ABSORB THE SNOW. ONLY THE 01.21Z SREF YIELDS A
SMALL POSSIBILITY OF SNOW ACROSS MUCH OF EASTERN MINNESOTA SUNDAY
MORNING. WILL LEAN TOWARDS THE MAJORITY IDEA AND KEEP A DRY FORECAST
GOING.
2. ACCUMULATING SNOW POTENTIAL SUNDAY NIGHT THROUGH TUESDAY...
GOOD MODEL AGREEMENT EXISTS THAT A FRONTOGENETIC BAND OF
PRECIPITATION WILL FORM FROM THE DAKOTAS SOUTHEAST INTO NORTHWEST
IOWA BY LATE SUNDAY. THIS BAND FORMS BECAUSE OF INTENSIFYING WARM
ADVECTION COMBINING WITH PACIFIC MOISTURE...DOWNSTREAM OF THE POTENT
TROUGH CURRENTLY IN THE EAST PACIFIC MOVING INTO MONTANA.
WHERE THE FRONTOGENETIC BAND GOES FROM HERE IN TIME HAS BEEN
PROBLEMATIC THE LAST COUPLE DAYS...AND THERE REMAINS PROBLEMS TODAY.
PART OF THE ISSUE IS SOLELY JUST ON THE POTENT TROUGH TRACK AND
SPEED. THE SPREAD AT 00Z TUESDAY RANGES FROM THE EASTERN DAKOTAS IN
THE 02.00Z NAM...CENTRAL DAKOTAS IN THE 02.00Z UKMET/ECMWF...AND THE
WESTERN DAKOTAS IN THE 02.00Z CANADIAN/GFS. IT IS WORTH NOTING THAT
THE LOCATION FROM ALL MODELS IS DEFINITELY WEST AND SLOWER THAN
THOSE SEEN FROM THE 01.00Z CYCLE. THE FASTER NAM WOULD BRING THE
FRONTOGENETIC SNOW BAND TO MUCH OF THE AREA ON MONDAY...WITH
POTENTIALLY SOME MODERATE TO HEAVY SNOW IN LA CROSSE. HOWEVER...THE
NAM HAS BEEN CONSIDERED AN OUTLIER SOLUTION. FOR THE WESTERN GROUP
OF THE CANADIAN/GFS...THIS GROUP WOULD ONLY BRING SOME LIGHT SNOW TO
A PORTION OF NORTHEAST IOWA AND THE AUSTIN AREA SUNDAY NIGHT. THE
SNOW THEN EXPANDS EAST A LITTLE ON MONDAY AND EXITS TO THE SOUTHEAST
TUESDAY AFTERNOON. FINALLY THE UKMET/ECMWF ARE KIND OF A COMPROMISE
BETWEEN THE GFS/CANADIAN AND THE NAM.
GIVEN THE DEFINITE SLOW DOWN SIGNAL PRESENT IN ALL MODELS WITH THE
UPPER TROUGH...HAVE TRENDED THE FORECAST THIS WAY. THE RESULT IS TO
THE KEEP THE HIGHEST PRECIPITATION CHANCES IN THE FAR WEST
SOUTHEASTERN MINNESOTA COUNTIES INTO NORTHEAST IOWA FOR LATE SUNDAY
NIGHT THROUGH TUESDAY...WITH LOWER CHANCES TO PRACTICALLY DRY BY THE
TIME YOU HEAD EAST TOWARDS I-94. APPEARS THERE COULD BE TWO
PERIODS OF MORE MODERATE SNOWFALL...ONE WITH THE INITIAL WAVE OF
FRONTOGENESIS/WARM ADVECTION...THEN THE SECOND AND FINAL ONE
ACCOMPANYING THE UPPER TROUGH AS IT DIGS SOUTH INTO MISSOURI ON
TUESDAY.
STILL GIVEN THE MODEL VARIABILITY...IT IS HARD TO SPECULATE ON
SNOWFALL AMOUNTS. ONE CONCERN IS THAT THE MAXIMUM QPF WHEREVER THE
FRONTOGENESIS BAND LAYS UP COULD END UP AT OR ABOVE 1 INCH...
ACCORDING TO THE CANADIAN...GFS...NAM AND SREF. THE ECMWF SUGGEST
HALF OF THAT...BUT THE LOWER TOTAL MAY BE A RESULT OF THE 80 KM
HORIZONTAL RESOLUTION AS WELL AS WEAKER FORCING. THE LIQUID QPF
COMBINED WITH SNOW TO WATER RATIOS LIKELY IN THE 10-15 TO 1 RANGE
FOR THIS EVENT WOULD RESULT IN 36 HOUR TOTALS OF 10 TO 12
INCHES...POSSIBLY MORE. THUS...A WINTER STORM WATCH MAY BE REQUIRED.
RIGHT NOW CONFIDENCE IS JUST NOT HIGH ENOUGH TO ISSUE THE WATCH
BECAUSE OF PLACEMENT PROBLEMS WITH THE SNOW BAND.
3. TEMPERATURES THROUGHOUT THE SHORT TERM...
TEMPERATURES TODAY LOOK TO END UP SIMILAR TO YESTERDAY GIVEN PLENTY
OF SUN BUT THE COOLER START AND 850MB TEMPS HOLDING NEARLY STEADY.
TONIGHT COULD GET QUITE CHILLY...PRIMARILY OVER WISCONSIN WHERE THE
MID/HIGH CLOUDS TAKE LONGER TO ARRIVE. STAYED TOWARDS THE COOL SIDE
OF GUIDANCE OVER WISCONSIN. THE DIURNAL CHANGE SHRINKS FOR SUNDAY
THROUGH MONDAY NIGHT...THOUGH READINGS DO LOOK WARMER... WITH PLENTY
OF CLOUDS AROUND FROM THE SYSTEM AFFECTING THE AREA. WENT WITH A
BLEND OF GUIDANCE FOR HIGHS/LOWS SUNDAY THROUGH MONDAY NIGHT.
.LONG TERM...TUESDAY NIGHT THROUGH FRIDAY NIGHT
215 AM CST SAT MAR 2 2013
MODEL AGREEMENT AMONGST THE 02.00Z ECMWF/CANADIAN/GFS AND GFS
ENSEMBLES IS PRETTY GOOD THROUGH THE LONG TERM PERIOD. GENERAL IDEA
IS THAT THE UPPER TROUGH AFFECTING THE AREA ON TUESDAY WILL HEAD
SOUTHEAST INTO THE MID-ATLANTIC REGION BY WEDNESDAY...PUSHED ALONG
BY UPPER RIDGING BUILDING EAST/NORTH INTO THE PLAINS. THUS...DRIER
CONDITIONS ARE ANTICIPATED ACROSS THE ENTIRE AREA FOR TUESDAY NIGHT
INTO WEDNESDAY.
DEFINITE PATTERN SHIFT FORECAST THROUGH THE REST OF THE WEEK WITH
TROUGHING OVER THE WESTERN U.S. AND RIDGING SHIFTING EAST AND
BUILDING OVER THE EASTERN U.S.. IN ADDITION...IT APPEARS THE UPPER
TROUGHING IN THE WESTERN U.S. IS EVENTUALLY GOING TO SPLIT INTO
TWO...WITH THE SOUTHERN PART CUTTING OFF IN THE SOUTHWEST U.S. AND
THE NORTHERN PART BRINGING A COLD FRONT THROUGH THE AREA COME
FRIDAY. PERHAPS WE MAY SEE SOME LIGHT PRECIPITATION WITH THIS
FRONTAL PASSAGE THURSDAY NIGHT INTO FRIDAY...BUT THE FRONT IS
MOISTURE AND FORCING STARVED. THUS...ONLY HAVE 20 PERCENT CHANCES AT
THE PRESENT TIME. OTHERWISE...DRY CONDITIONS PREVAIL. TEMPERATURES
ARE GOING TO BE ON THE RISE AS WELL...ESPECIALLY COME FRIDAY AHEAD
OF THE COLD FRONT. BY FRIDAY...HIGHS APPEAR ABOVE NORMAL. EVEN
BEHIND THE FRONT LOOKING AHEAD TO THE WEEKEND...THE AIRMASS DOES NOT
LOOK THAT COLD GIVEN A PACIFIC FLOW OF AIR IN ITS WAKE.
&&
.AVIATION...
1010 PM CST FRI MAR 1 2013
LATEST FOG/STRATUS SATELLITE IMAGERY SHOWING THE MVFR CLOUDS WELL
SOUTH OF THE TAF SITES...AND CONTINUING A SOUTHWARD PROPAGATION
ACROSS CENTRAL/SOUTHERN IA. LATEST RAP RH FIELDS HAVE ALSO BACKED
OFF ON ITS PREVIOUS ABUNDANCE OF SUB 900 MB MOISTURE...WHICH LED TO
SOME CONCERNS OF STRATUS FORMATION. THIS LOOKS LIKE LESS OF A
POSSIBILITY AND WILL CONTINUE VFR THROUGH THE OVERNIGHT HOURS INTO
SAT MORNING. NAM/GFS/RAP ALL SHOW SOME INCREASE IN LOW LEVEL
HUMIDITY FOR SAT AFTERNOON...FROM EASTERN WI...DECREASING AS YOU
REACH THE MISSISSIPPI RIVER. BELIEVE THIS WILL TRANSLATE INTO SOME
CU. CAN/T RULE OUT SOME BKN CIGS AT KLSE...AND IF SO...WOULD LIKELY
BE AROUND 2.5 KFT. CONFIDENCE LIES WITH A SCT DECK AT THIS MOMENT
THOUGH...AND WILL STICK WITH IT.
LIGHT WIND FIELD SAT NIGHT AS HIGH PRESSURE WORKS OVERHEAD. EXPECT
SOME HIGH CLOUDS HOWEVER AS AN UPPER LEVEL TROUGH AS TRACKS EASTWARD
ACROSS THE REGION. IF NOT FOR THE HIGH CLOUDS...THERE COULD BE A
THREAT FOR SOME BR. LATEST OBSERVATIONS TO THE WEST UNDER THE HIGH
INDICATE SOME VSBY RESTRICTIONS FROM BR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
215 AM CST SAT MAR 2 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
215 AM CST SAT MAR 2 2013
.SHORT TERM...TODAY THROUGH TUESDAY
215 AM CST SAT MAR 2 2013
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED RIDGING AGAIN OVER THE WESTERN U.S. AND BEGINNING TO ENTER
THE WESTERN PORTION OF THE PLAINS...WHILE TROUGHING STILL
DOMINATED THE EASTERN U.S. A SHORTWAVE TROUGH WAS EVIDENT OVER THE
FORECAST AREA...PRODUCING SOME CIRRUS AHEAD OF IT OVER EASTERN
WISCONSIN. OTHERWISE...THE AIRMASS HAS DRIED OUT QUITE A
BIT...NOTED BY THE 00Z MPX SOUNDING WITH A PRECIPITABLE WATER OF
0.17 INCHES OR 71 PERCENT OF NORMAL. A LIGHT NORTHERLY BREEZE
CONTINUES AHEAD OF A HIGH PRESSURE RIDGE IN FAR WESTERN MINNESOTA.
THIS BREEZE HAS SO FAR KEPT TEMPERATURES FROM COMPLETELY
PLUMMETING. FARTHER WEST...MID AND HIGH CLOUDS WERE INCREASING
ACROSS THE DAKOTAS AHEAD OF THE BUILDING UPPER RIDGE...IN A
GENERAL WARM ADVECTION PATTERN. NO EVIDENCE YET OF PRECIPITATION
FALLING OUT OF THEM...LIKELY DUE TO THE DRY AIR BETWEEN 600-800MB
ON THE 00Z BIS SOUNDING. AIRMASS AROUND THE NORTHERN PLAINS HAS
WARMED UP SOMEWHAT WITH 850MB TEMPS FROM ABR TO MPX AND GRB AROUND
-8C PER 00Z SOUNDINGS. THE MPX AND GRB OBSERVATIONS WERE ABOUT 2C
WARMER THAN WHAT 01.00Z MODELS FORECASTED. WELL OFF TO THE
WEST...A POTENT UPPER TROUGH WAS LOCATED OVER THE EAST PACIFIC
NEAR 45 N 139 W...WHICH WE ARE WATCHING FOR EARLY NEXT WEEK.
SHORT TERM HIGHLIGHTS / CONCERNS...
1. POTENTIAL FOR SOME LIGHT SNOW LATE TONIGHT/SUNDAY MORNING...
THE AREA OF THICKENING MID/HIGH CLOUDS ACROSS THE DAKOTAS WILL
EVENTUALLY SHIFT OVER THE FORECAST AREA TONIGHT AS THE WESTERN U.S.
RIDGE GETS PUSHED EASTWARD. ACCOMPANYING THE MID/HIGH CLOUDS IS SOME
LOW TO MID LEVEL FRONTOGENESIS AND WEAK ISENTROPIC LIFT ON THE
280-285K SURFACES. THE MAIN QUESTION IS IF ANY SNOW THAT IS PRODUCED
OUT OF THESE CLOUDS AND LIFT CAN MAKE IT TO THE SURFACE. THE 02.00Z
GFS/NAM/ECMWF/CANADIAN ARE ALL DRY...SUGGESTING THAT THE LOW LEVEL
DRY AIR LEFT BEHIND BY THE SURFACE RIDGE CROSSING THE FORECAST AREA
WILL BE ENOUGH TO ABSORB THE SNOW. ONLY THE 01.21Z SREF YIELDS A
SMALL POSSIBILITY OF SNOW ACROSS MUCH OF EASTERN MINNESOTA SUNDAY
MORNING. WILL LEAN TOWARDS THE MAJORITY IDEA AND KEEP A DRY FORECAST
GOING.
2. ACCUMULATING SNOW POTENTIAL SUNDAY NIGHT THROUGH TUESDAY...
GOOD MODEL AGREEMENT EXISTS THAT A FRONTOGENETIC BAND OF
PRECIPITATION WILL FORM FROM THE DAKOTAS SOUTHEAST INTO NORTHWEST
IOWA BY LATE SUNDAY. THIS BAND FORMS BECAUSE OF INTENSIFYING WARM
ADVECTION COMBINING WITH PACIFIC MOISTURE...DOWNSTREAM OF THE POTENT
TROUGH CURRENTLY IN THE EAST PACIFIC MOVING INTO MONTANA.
WHERE THE FRONTOGENETIC BAND GOES FROM HERE IN TIME HAS BEEN
PROBLEMATIC THE LAST COUPLE DAYS...AND THERE REMAINS PROBLEMS TODAY.
PART OF THE ISSUE IS SOLELY JUST ON THE POTENT TROUGH TRACK AND
SPEED. THE SPREAD AT 00Z TUESDAY RANGES FROM THE EASTERN DAKOTAS IN
THE 02.00Z NAM...CENTRAL DAKOTAS IN THE 02.00Z UKMET/ECMWF...AND THE
WESTERN DAKOTAS IN THE 02.00Z CANADIAN/GFS. IT IS WORTH NOTING THAT
THE LOCATION FROM ALL MODELS IS DEFINITELY WEST AND SLOWER THAN
THOSE SEEN FROM THE 01.00Z CYCLE. THE FASTER NAM WOULD BRING THE
FRONTOGENETIC SNOW BAND TO MUCH OF THE AREA ON MONDAY...WITH
POTENTIALLY SOME MODERATE TO HEAVY SNOW IN LA CROSSE. HOWEVER...THE
NAM HAS BEEN CONSIDERED AN OUTLIER SOLUTION. FOR THE WESTERN GROUP
OF THE CANADIAN/GFS...THIS GROUP WOULD ONLY BRING SOME LIGHT SNOW TO
A PORTION OF NORTHEAST IOWA AND THE AUSTIN AREA SUNDAY NIGHT. THE
SNOW THEN EXPANDS EAST A LITTLE ON MONDAY AND EXITS TO THE SOUTHEAST
TUESDAY AFTERNOON. FINALLY THE UKMET/ECMWF ARE KIND OF A COMPROMISE
BETWEEN THE GFS/CANADIAN AND THE NAM.
GIVEN THE DEFINITE SLOW DOWN SIGNAL PRESENT IN ALL MODELS WITH THE
UPPER TROUGH...HAVE TRENDED THE FORECAST THIS WAY. THE RESULT IS TO
THE KEEP THE HIGHEST PRECIPITATION CHANCES IN THE FAR WEST
SOUTHEASTERN MINNESOTA COUNTIES INTO NORTHEAST IOWA FOR LATE SUNDAY
NIGHT THROUGH TUESDAY...WITH LOWER CHANCES TO PRACTICALLY DRY BY THE
TIME YOU HEAD EAST TOWARDS I-94. APPEARS THERE COULD BE TWO
PERIODS OF MORE MODERATE SNOWFALL...ONE WITH THE INITIAL WAVE OF
FRONTOGENESIS/WARM ADVECTION...THEN THE SECOND AND FINAL ONE
ACCOMPANYING THE UPPER TROUGH AS IT DIGS SOUTH INTO MISSOURI ON
TUESDAY.
STILL GIVEN THE MODEL VARIABILITY...IT IS HARD TO SPECULATE ON
SNOWFALL AMOUNTS. BEST GUESS AT THIS TIME WOULD BE FLOYD COUNTY IOWA
HAVING THE MOST...PERHAPS UP TO 6 INCHES FROM SUNDAY NIGHT THROUGH
TUESDAY. THIS IS A LONG DRAWN OUT SNOW. SHOULD THE 02.00Z NAM
SCENARIO PLAY OUT...WE DEFINITELY WOULD BE LOOKING AT MORE
SNOW...AND FARTHER EAST.
3. TEMPERATURES THROUGHOUT THE SHORT TERM...
TEMPERATURES TODAY LOOK TO END UP SIMILAR TO YESTERDAY GIVEN PLENTY
OF SUN BUT THE COOLER START AND 850MB TEMPS HOLDING NEARLY STEADY.
TONIGHT COULD GET QUITE CHILLY...PRIMARILY OVER WISCONSIN WHERE THE
MID/HIGH CLOUDS TAKE LONGER TO ARRIVE. STAYED TOWARDS THE COOL SIDE
OF GUIDANCE OVER WISCONSIN. THE DIURNAL CHANGE SHRINKS FOR SUNDAY
THROUGH MONDAY NIGHT...THOUGH READINGS DO LOOK WARMER... WITH PLENTY
OF CLOUDS AROUND FROM THE SYSTEM AFFECTING THE AREA. WENT WITH A
BLEND OF GUIDANCE FOR HIGHS/LOWS SUNDAY THROUGH MONDAY NIGHT.
.LONG TERM...TUESDAY NIGHT THROUGH FRIDAY NIGHT
215 AM CST SAT MAR 2 2013
MODEL AGREEMENT AMONGST THE 02.00Z ECMWF/CANADIAN/GFS AND GFS
ENSEMBLES IS PRETTY GOOD THROUGH THE LONG TERM PERIOD. GENERAL IDEA
IS THAT THE UPPER TROUGH AFFECTING THE AREA ON TUESDAY WILL HEAD
SOUTHEAST INTO THE MID-ATLANTIC REGION BY WEDNESDAY...PUSHED ALONG
BY UPPER RIDGING BUILDING EAST/NORTH INTO THE PLAINS. THUS...DRIER
CONDITIONS ARE ANTICIPATED ACROSS THE ENTIRE AREA FOR TUESDAY NIGHT
INTO WEDNESDAY.
DEFINITE PATTERN SHIFT FORECAST THROUGH THE REST OF THE WEEK WITH
TROUGHING OVER THE WESTERN U.S. AND RIDGING SHIFTING EAST AND
BUILDING OVER THE EASTERN U.S.. IN ADDITION...IT APPEARS THE UPPER
TROUGHING IN THE WESTERN U.S. IS EVENTUALLY GOING TO SPLIT INTO
TWO...WITH THE SOUTHERN PART CUTTING OFF IN THE SOUTHWEST U.S. AND
THE NORTHERN PART BRINGING A COLD FRONT THROUGH THE AREA COME
FRIDAY. PERHAPS WE MAY SEE SOME LIGHT PRECIPITATION WITH THIS
FRONTAL PASSAGE THURSDAY NIGHT INTO FRIDAY...BUT THE FRONT IS
MOISTURE AND FORCING STARVED. THUS...ONLY HAVE 20 PERCENT CHANCES AT
THE PRESENT TIME. OTHERWISE...DRY CONDITIONS PREVAIL. TEMPERATURES
ARE GOING TO BE ON THE RISE AS WELL...ESPECIALLY COME FRIDAY AHEAD
OF THE COLD FRONT. BY FRIDAY...HIGHS APPEAR ABOVE NORMAL. EVEN
BEHIND THE FRONT LOOKING AHEAD TO THE WEEKEND...THE AIRMASS DOES NOT
LOOK THAT COLD GIVEN A PACIFIC FLOW OF AIR IN ITS WAKE.
&&
.AVIATION...
1010 PM CST FRI MAR 1 2013
LATEST FOG/STRATUS SATELLITE IMAGERY SHOWING THE MVFR CLOUDS WELL
SOUTH OF THE TAF SITES...AND CONTINUING A SOUTHWARD PROPAGATION
ACROSS CENTRAL/SOUTHERN IA. LATEST RAP RH FIELDS HAVE ALSO BACKED
OFF ON ITS PREVIOUS ABUNDANCE OF SUB 900 MB MOISTURE...WHICH LED TO
SOME CONCERNS OF STRATUS FORMATION. THIS LOOKS LIKE LESS OF A
POSSIBILITY AND WILL CONTINUE VFR THROUGH THE OVERNIGHT HOURS INTO
SAT MORNING. NAM/GFS/RAP ALL SHOW SOME INCREASE IN LOW LEVEL
HUMIDITY FOR SAT AFTERNOON...FROM EASTERN WI...DECREASING AS YOU
REACH THE MISSISSIPPI RIVER. BELIEVE THIS WILL TRANSLATE INTO SOME
CU. CAN/T RULE OUT SOME BKN CIGS AT KLSE...AND IF SO...WOULD LIKELY
BE AROUND 2.5 KFT. CONFIDENCE LIES WITH A SCT DECK AT THIS MOMENT
THOUGH...AND WILL STICK WITH IT.
LIGHT WIND FIELD SAT NIGHT AS HIGH PRESSURE WORKS OVERHEAD. EXPECT
SOME HIGH CLOUDS HOWEVER AS AN UPPER LEVEL TROUGH AS TRACKS EASTWARD
ACROSS THE REGION. IF NOT FOR THE HIGH CLOUDS...THERE COULD BE A
THREAT FOR SOME BR. LATEST OBSERVATIONS TO THE WEST UNDER THE HIGH
INDICATE SOME VSBY RESTRICTIONS FROM BR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
215 AM CST SAT MAR 2 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1010 PM CST FRI MAR 1 2013
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
318 PM CST FRI MAR 1 2013
AT 3 PM...HIGH PRESSURE WAS LOCATED OVER HUDSON BAY. A RIDGE OF
HIGH PRESSURE EXTENDS SOUTHWEST INTO WESTERN MINNESOTA. CLOSER
HOME...THE FORECAST AREA IS STILL UNDER THE INFLUENCE OF A LOW
PRESSURE SYSTEM OFF OF THE NEW ENGLAND COAST. THIS LOW KEPT THE
AREA MOSTLY CLOUDY THIS MORNING...BUT SKIES HAVE BEEN CLEARING
FROM NORTHEAST TO SOUTHWEST AS DRIER AIR MOVES INTO THE REGION.
THIS TREND IS EXPECTED TO CONTINUE THROUGH THE REMAINDER OF THE
AFTERNOON AND EVENING.
FOR TONIGHT...THE 01.12Z MODELS SHOW A WEAKENING SHORT WAVE TROUGH
MOVE EAST THROUGH THE FORECAST AREA. THIS SYSTEM PRODUCES SOME
WEAK OMEGA BETWEEN 600 AND 300 MB. THIS LIFT WILL AID IN THE
GENERATION OF A FEW MID AND HIGH CLOUDS AS THE 290-310K ISENTROPIC
DEFICITS DECREASE TO 10 TO 30 MB.
ON SATURDAY NIGHT...ANOTHER SHORT WAVE TROUGH WILL MOVE EAST
THROUGH THE REGION. WEAK TO MODERATE 280K ISENTROPIC LIFT DEVELOPS
AHEAD OF THIS WAVE. THIS HELPS THE CONDENSATION PRESSURE DEFICITS
TO DROP TO 10 MB OR LESS. WHILE THERE IS SATURATION BETWEEN 850
AND 750 MB...THE AIR MASS BELOW REMAINS VERY DRY IN THE BUFKIT
SOUNDINGS...THUS KEPT THE FORECAST DRY.
ON SUNDAY NIGHT...MOST OF THE 01.12Z MODELS SHIFTED BACK TO THE
SOUTH FROM THE 01.00Z AND 01.06Z MODELS. THE LONE EXCEPTION IS THE
NAM WHICH IS MUCH FURTHER NORTHEAST WITH ITS TRACK.
OVERALL...PREFER THE GFS TRACK THE BEST. IT HAS BEEN BY FAR...THE
MOST CONSISTENT MODEL WITH THE TRACK OF THIS SYSTEM...THEREFORE...
THE FORECAST WAS TRENDED TOWARD IT. AS A SYSTEM MOVES SOUTHEAST
INTO THE NORTHERN PLAINS FROM THE CANADIAN PROVIDENCES...800 TO
700 MB FRONTOGENESIS WILL DEVELOP ACROSS SOUTHERN MINNESOTA...AND
NORTHERN AND EASTERN IOWA. THIS WILL RESULT IN A BAND OR BANDS OF
SNOW ACROSS THIS AREA. THE HIGHEST PRECIPITATION PROBABILITIES AND
QPF WAS TRENDED TOWARD THAT AREA. AT THIS TIME...SNOW AMOUNTS LOOK
TO BE UP TO AN INCH.
.LONG TERM...MONDAY THROUGH FRIDAY
318 PM CST FRI MAR 1 2013
ON MONDAY...CONTINUED TO TREND THE FORECAST TOWARD THE MORE
CONSISTENT GFS. IT SHOWS WEAK TO MODERATE 800 TO 600 MB FRONTOGENESIS
CONTINUING TO BE FOUND ACROSS SOUTHERN MINNESOTA AND NORTHERN AND
EASTERN IOWA. SOUNDINGS CONTINUE TO SUGGEST THAT THE PRECIPITATION
WILL BE SNOW WITH AMOUNTS LESS THAN AN INCH.
ON MONDAY NIGHT AND TUESDAY...BOTH THE GEM AND GFS SHOW THAT
ANOTHER WAVE WILL MOVE SOUTHWEST OF THE FORECAST AREA. MEANWHILE
THE ECMWF IS MUCH FURTHER NORTHEAST AND IT PRODUCES SNOW ACROSS
SOUTHEAST MINNESOTA AND NORTHEAST IOWA. ORIGINALLY WAS LEANING
TOWARD THE GEM AND GFS SOLUTIONS. HOWEVER 5 OF THE 12 GFS FAMILY
MEMBERS DO SUPPORT THE ECMWF...SO STAYED WITH THE ALL BLEND. SNOW
AMOUNTS AT THIS TIME LOOK TO BE LESS THAN AN INCH.
&&
.AVIATION...
1010 PM CST FRI MAR 1 2013
LATEST FOG/STRATUS SATELLITE IMAGERY SHOWING THE MVFR CLOUDS WELL
SOUTH OF THE TAF SITES...AND CONTINUING A SOUTHWARD PROPAGATION
ACROSS CENTRAL/SOUTHERN IA. LATEST RAP RH FIELDS HAVE ALSO BACKED
OFF ON ITS PREVIOUS ABUNDANCE OF SUB 900 MB MOISTURE...WHICH LED TO
SOME CONCERNS OF STRATUS FORMATION. THIS LOOKS LIKE LESS OF A
POSSIBILITY AND WILL CONTINUE VFR THROUGH THE OVERNIGHT HOURS INTO
SAT MORNING. NAM/GFS/RAP ALL SHOW SOME INCREASE IN LOW LEVEL
HUMIDITY FOR SAT AFTERNOON...FROM EASTERN WI...DECREASING AS YOU
REACH THE MISSISSIPPI RIVER. BELIEVE THIS WILL TRANSLATE INTO SOME
CU. CAN/T RULE OUT SOME BKN CIGS AT KLSE...AND IF SO...WOULD LIKELY
BE AROUND 2.5 KFT. CONFIDENCE LIES WITH A SCT DECK AT THIS MOMENT
THOUGH...AND WILL STICK WITH IT.
LIGHT WIND FIELD SAT NIGHT AS HIGH PRESSURE WORKS OVERHEAD. EXPECT
SOME HIGH CLOUDS HOWEVER AS AN UPPER LEVEL TROUGH AS TRACKS EASTWARD
ACROSS THE REGION. IF NOT FOR THE HIGH CLOUDS...THERE COULD BE A
THREAT FOR SOME BR. LATEST OBSERVATIONS TO THE WEST UNDER THE HIGH
INDICATE SOME VSBY RESTRICTIONS FROM BR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
318 PM CST FRI MAR 1 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM....BOYNE
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS LINCOLN IL
556 AM CST SAT MAR 2 2013
.DISCUSSION...
ISSUED 240 AM CST SAT MAR 2 2013
PESKY LONG-LASTING LIGHT SNOW IS FINALLY BEGINNING TO EXIT THE
AREA...AND WAS MAINLY SOUTH OF I-70 EARLY THIS MORNING. LOW CLOUD
DECK HAS BEEN ERODING FROM THE NORTH AND SOME BREAKS HAVE
DEVELOPED AS FAR SOUTH AS PEORIA...BUT STILL PLENTY OF CLOUDINESS
OVER THE AREA.
MAIN FORECAST CONCERNS INVOLVE PRECIPITATION CHANCES EARLY NEXT
WEEK.
SHORT TERM...TODAY THROUGH TUESDAY...
MOSTLY DRY CONDITIONS EXPECTED TODAY FOR A CHANGE. WILL NEED TO
MONITOR FOR SOME LINGERING LIGHT SNOW SHOWERS ACROSS THE EASTERN
CWA TODAY...ESPECIALLY WITH THE WIND TRAJECTORY COMING OFF LAKE
MICHIGAN. CLOUDS MAY BE A BIT SLOWER TO ERODE...WITH 925-850 MB
HUMIDITY PLOT OFF THE RAP MODEL KEEPING A FAIR AMOUNT OF
CLOUDINESS EAST OF I-55 WELL INTO THE AFTERNOON. HOWEVER...
CLEARING LATER TODAY AND TONIGHT WILL PRECEDE A RIDGE OF HIGH
PRESSURE THAT WILL CROSS THE STATE ON SUNDAY.
DEEP UPPER TROUGHING OVER THE EASTERN U.S. TO PUSH EASTWARD ON
SUNDAY...AS A SHORTWAVE IN SOUTHWEST CANADA BEGINS TO CLOSE OFF
AND DROP INTO THE NORTHERN PLAINS EARLY NEXT WEEK. PRECIP CHANCES
EARLY NEXT WEEK WILL FOCUS ON A COUPLE FEATURES. THE FIRST WILL BE
WITH THE STRONG WARM AIR ADVECTION THAT WILL TAKE PLACE LATE
SUNDAY NIGHT...WITH EVENING MODELS IN FAIRLY GOOD AGREEMENT IN
DEVELOPMENT OF SOME LIGHT SNOW ACROSS THE WESTERN CWA AFTER
MIDNIGHT...AND SPREADING OVER MUCH OF THE CWA ON MONDAY. SHOULD
SEE SOME TRANSITION OVER TO RAIN DURING THE DAY ACROSS THE SOUTH
HALF OF THE FORECAST AREA...AS TEMPERATURES RISE TO AROUND THE 40
DEGREE MARK. SECOND FOCUS WILL BE AS LOW PRESSURE DEVELOPS OVER
THE CENTRAL PLAINS AND TOWARD THE WESTERN OHIO VALLEY BY TUESDAY
MORNING...WITH AN INVERTED SURFACE TROUGH EXTENDING NORTHWEST
TOWARD THE UPPER LOW. HAVE MAINTAINED HEALTHY PRECIP CHANCES
THROUGH TUESDAY WITH THESE FEATURES...MOSTLY AS SNOW BUT WITH SOME
RAIN ACROSS THE SOUTHEAST. POTENTIAL EXISTS FOR ANOTHER 1 TO 3
INCHES OF SNOW EARLY NEXT WEEK.
LONG TERM...WEDNESDAY THROUGH FRIDAY...
UPPER LOW SHOULD MAKE SOME STEADY PROGRESS SOUTHEAST AND FORM A
STRONG STORM SYSTEM OFF THE CAROLINA COAST BY MIDWEEK. THIS WILL
ALLOW FOR SOME UPPER RIDGING ACROSS THE CENTER OF THE NATION...
WITH MODERATING TEMPERATURES AS A SOUTHWEST UPPER FLOW SETS UP
LATER IN THE WEEK...AND HIGHS ARE LIKELY TO RETURN TO THE 50S BY
FRIDAY. ANY PRECIPITATION IS EXPECTED TO HOLD OFF UNTIL NEXT
WEEKEND...BEYOND THE CURRENT FORECAST PERIOD.
GEELHART
&&
.AVIATION...
ISSUED 556 AM CST SAT MAR 2 2013
PREDOMINANTLY VFR CONDITIONS EXPECTED ACROSS THE CENTRAL ILLINOIS
TERMINALS THROUGH THE 12Z TAF VALID TIME. THE PERSISTENT AREA OF
LOW CLOUDINESS...AS WELL AS A FEW FLURRIES...WILL GRADUALLY MOVE
OUT OF THE AREA TODAY AS HIGH PRESSURE STARTS TO BUILD ACROSS THE
TERMINALS. NORTHERLY WINDS TO THE EAST OF THE RIDGE AXIS SHOULD
TREND LIGHT/VARIABLE TONIGHT WITH THE APPROACH OF THE RIDGE.
BAK
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
523 AM CST SAT MAR 2 2013
.AVIATION...
A RIDGE OF HIGH PRESSURE WILL MIGRATE EAST OUT OF THE PLAINS...
PROVIDING VFR CONDITIONS TODAY AND TONIGHT. THERE IS A LOW
POTENTIAL FOR PATCHY FOG TOWARD SUNDAY MORNING...BUT CONFIDENCE IS
TOO LOW TO INCLUDE IN THE FORECASTS. LIGHT NORTH TO NORTHWEST
WINDS WILL INCREASE TO NEAR 10 KNOTS TODAY...THEN BECOME LIGHT AND
VARIABLE OVERNIGHT.
SHEETS
&&
.PREV DISCUSSION... /ISSUED 324 AM CST SAT MAR 2 2013/
SYNOPSIS...
LATEST IR SATELLITE IMAGERY INDICATED THE NORTH TO SOUTH CLEARING
TREND OF LOW CLOUDS HAD COME TO A HALT ROUGHLY ALONG THE I-80
CORRIDOR OVER THE PAST FEW HOURS. SURFACE ANALYSIS INDICATED A LEE
TROUGH ACROSS THE WESTERN HIGH PLAINS FLANKED BY HIGH PRESSURE
REACHING FROM THE EASTERN DAKOTAS TO KS. OVER THE LOCAL AREA...A
LIGHT N-NE 925 MB AND 850 MB FLOW CONTINUED TO FEED MOISTURE FROM
THE GREAT LAKES...AND DEPARTING STORM SYSTEM INTO ESPECIALLY THE IL
SIDE OF THE FORECAST AREA. THIS TRAJECTORY SHOULD FINALLY BREAK DOWN
TODAY AS THE WESTERN U.S. UPPER RIDGE BUILDS AND EDGES EASTWARD...
PUSHING THE SURFACE RIDGE...AND A WEAK MID LEVEL ANTICYCLONE OVER
SOUTHERN LAKE MI EASTWARD.
SHORT TERM...TODAY AND TONIGHT...
MAIN CHALLENGES ARE CENTERED ON CLOUD AND TEMPERATURE TRENDS. SHORT
TERM MODELS GENERALLY DEPICT THE MOISTURE LAYER AROUND 925 MB
ASSOCIATED WITH THE STRATUS DECK...THAT WAS COVERING MUCH OF WESTERN
AND SOUTHERN IA...SHIFTING SOUTHWARD TODAY. EAST OF THE MS
RIVER...THE EXTENSIVE STRATUS DECK IS SHOWN MAKING A WESTWARD
RESURGENCE IN THE AFTERNOON AFTER CLEARING THIS MORNING. THIS IS
MOST PRONOUNCED IN THE LATEST RAP RH FIELDS. FOR NOW...WILL KEEP A
MORE OPTIMISTIC FORECAST OF MOSTLY SUNNY SKIES OVER THE ENTIRE AREA
BY AFTERNOON...COUNTING ON THE EFFECTS OF INCREASING MID LEVEL
SUBSIDENCE WITH THE INCOMING UPPER LEVEL RIDGE. EVEN WITH
SUNSHINE...LOOKING AT HIGHS FROM UPSTREAM YESTERDAY AND CONSIDERING
925 MB TEMPERATURES THAT WILL BE SIMILAR TO YESTERDAY...HIGHS FROM
THE UPPER 20S NORTH TO LOWER 30S LOOK REASONABLE.
TONIGHT...THE SURFACE RIDGE TO THE WEST WEAKENS AS IT PASSES THROUGH
THE AREA ALLOWING WINDS TO BECOME LIGHT AND VARIABLE TOWARD MORNING.
SKIES SHOULD INITIALLY BE MOSTLY CLEAR...BUT THERE WILL BE A THREAT
OF INCREASING HIGH CLOUDS IN THE NW FLOW ALOFT. THIS WOULD PREVENT
TEMPERATURES FROM BOTTOMING OUT OVER OUR EXTENSIVE SNOWFIELD AND
FOR NOW WILL COUNT ON THIS OCCURRING TO HOLD MINS NO LOWER THAN
AROUND 10 NORTH TO THE MID TEENS SOUTH. IF HIGH CLOUDS DO NOT
MATERIALIZE...WIDESPREAD SINGLE DIGITS WOULD BE LIKELY...SIMILAR
TO WHAT IS OCCURRING THIS MORNING.
SHEETS
LONG TERM...SUNDAY THROUGH FRIDAY...
SUNDAY NIGHT THROUGH TUESDAY...THE NEXT SYSTEM TO AFFECT THE UPPER
MISSISSIPPI VALLEY WILL OCCUR SUNDAY NIGHT THROUGH TUESDAY. MODEL
FORECASTS ARE INCONSISTENT WITH LARGE DIFFERENCES NOTED IN THE
PLACEMENT OF THE UPPER LOW. 06Z SATURDAY WATER VAPOR SATELLITE
IMAGERY SHOWS THE SYSTEM IS CURRENTLY OVER THE GULF OF ALASKA. MODEL
SOLUTIONS WILL LIKELY CONTINUE TO BE INCONSISTENT UNTIL THE WAVE
MOVES ONSHORE AND GETS BETTER SAMPLED BY THE UPPER AIR NETWORK. AT
12Z MONDAY ALL MODELS SHOW THE UPPER LOW OVER MONTANA BUT LARGE
DIFFERENCE IN PLACEMENT OCCUR AFTER THAT. BY 18Z TUESDAY THE NAM
MOVES THE UPPER LOW FROM MONTANA TO SOUTHERN MINNESOTA...THE
ECMWF/DGEX MOVE THE UPPER LOW ACROSS IOWA/ILLINOIS WHILE THE GFS
TAKES THE LOW SOUTH OF THE REGION ACROSS MISSOURI. EVEN WITH THE
UPPER LOW PLACEMENT PROBLEMS...ALL MODELS SHOW AN ELEVATED WARM
ADVECTION WING AHEAD OF THE SYSTEM WHICH WOULD BREAK OUT SNOW ACROSS
THE AREA BEFORE DAYBREAK MONDAY MORNING. FOR NOW I HAVE HAVE KEPT
CURRENT FORECAST CHANCE POPS FOR SUNDAY NIGHT BUT RAISED POPS TO
LIKELY CATEGORY FOR MONDAY MORNING. SNOW WILL CONTINUE INTO TUESDAY
AS UPPER FORCING INCREASES AS THE UPPER LOW MOVES CROSSES OVER OR
NEAR THE REGION.
BOTTOM LINE...CONFIDENCE IS HIGH SNOW WILL FALL IN OR NEAR OUR
FORECAST AREA MONDAY AND TUESDAY. CONFIDENCE IS LOW AS TO SPECIFIC
LOCATION AND TOTAL SNOW AMOUNTS.
WEDNESDAY THROUGH FRIDAY...LATER IN THE WEEK THE UPPER AIR PATTERN
SHIFTS TO A SOUTHWESTERLY FLOW AS AN UPPER LEVEL RIDGE LOCATED OVER
THE ROCKIES BEGINS TO MOVE EAST. SURFACE WINDS WILL BE SOUTHERLY
COMING AROUND THE WEST SIDE OF HIGH PRESSURE LOCATED OVER THE GREAT
LAKES/OHIO VALLEY. TEMPERATURES SHOULD BE CLOSE TO NORMAL THURSDAY
AND COULD EVEN BE ABOVE NORMAL BY FRIDAY. THE END OF NEXT WEEK LOOKS
TO BE DRY. ..KUHL..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1003 AM EST SAT MAR 2 2013
.SYNOPSIS...
ISSUED AT 315 AM EST SAT MAR 2 2013
HIGH PRESSURE WILL BRING FAIR AND DRY BUT COLD WEATHER THROUGH THE
WEEKEND. TEMPERATURES WILL UNDERGO A GRADUAL MODERATING TREND FOR
THE UPCOMING WEEK WITH TRANQUIL WEATHER EXPECTED TO CONTINUE.
&&
.UPDATE...
ISSUED AT 956 AM EST SAT MAR 2 2013
I UPDATED THE Z0NES FOR MORE CLOUDINESS INTO SUNDAY. I ALSO ADDED
FLURRIES INTO THIS EVENING. THE LATEST SATELLITE LOOPS SHOW ONLY
THE AREA NEAR AND EAST OF US-131 AND SOUTH OF BIG RAPIDS HAVING
ANY SUNSHINE. ALL OF THE MODELS SHOW THE CLOUDS WILL FILL IN THERE
TOO AS THE THERMAL TROUGH MOVES THROUGH. MOST OF THE REPORTING
STATIONS NORTH AND EAST OF GRR HAVE FLURRIES AND OUR RADAR HAS
SOME WEAK RETURNS EAST OF THE OFFICE WHICH ARE INCREASING AND
MOVING TO THE SOUTH SOUTHWEST. GIVEN THE FLURRIES ALREADY THERE AND
THE RAP MODEL SUGGESTING .03 AT GRR BTW 18Z AND 06Z IT SEEMS
PRUDENT TO PUT AT LEAST A FEW FLURRIES IN THE FORECAST. IF THE
SNOW SHOWER ACTIVITY INCREASES THAN I WILL UPDATE AGAIN.
&&
.SHORT TERM...(TODAY THROUGH MONDAY AFTERNOON)
ISSUED AT 315 AM EST SAT MAR 2 2013
HIGH PRESSURE WILL PRODUCE DRY BUT COLD WX THROUGH MONDAY WITH MAX
TEMPS THIS WEEKEND ONLY REACHING THE UPPER 20S TO LOWER 30S AND MIN
TEMPS MAINLY IN THE TEENS. SOME SINGLE DIGIT MINS ARE POSSIBLE THE
NEXT FEW NIGHTS NORTH OF I-96 GIVEN EXPANSIVE SNOW COVER AND
DEPENDENT LARGELY ON EXTENT OF CLEARING.
CURRENT IR SAT TREND CORROBORATED WITH 00Z NAM/GFS GUIDANCE TIME
HEIGHT RH PROGS SUGGEST WE WILL HAVE A MIX OF SUN AND CLOUDS TODAY
FOLLOWED BY A LITTLE MORE CLEARING TONIGHT. 00Z NUMERICAL GUIDANCE
AND TIME HEIGHT RH X-SECTIONS SUGGEST THE MOST EXTENSIVE CLEARING
SHOULD COME FOR MONDAY. THE EARLY MARCH SUNSHINE WILL HELP TO BOOST
MAX TEMPS INTO THE 30 TO 35 DEGREE RANGE MONDAY... WHICH IS STILL
SEVERAL DEGREES BELOW NORMAL FOR THIS TIME OF YEAR.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 315 AM EST SAT MAR 2 2013
MAIN FOCUS OF THE LONG TERM IS ON THE SHORTWAVE SEEN SPINNING TOWARD
THE BRITISH COLUMBIA COAST IN THE GULF OF ALASKA. THE WAVE PROVIDES
THE ONLY POSSIBILITY OF PRECIPITATION IN THE LONG TERM. THE GFS AND
ECMWF ARE AT ODDS WITH ONE ANOTHER IN THE TRACK OF THE WAVE SO IT IS
FAR FROM CERTAIN AS TO WHETHER IT BRINGS SW LOWER MI ANY PRECIP. THE
GFS DRIVES IT INTO THE HEART OF THE WESTERN RIDGE...WHILE THE ECMWF
SLIDES IT OVER THE TOP OF THE RIDGE A BIT MORE. THE ECMWF SEEMS A
BIT MORE PLAUSIBLE AND RESULTS IN A FARTHER NORTH TRACK. HAVE THROWN
SOME SMALL POPS (20/30 PCT) BACK INTO THE FORECAST DURING THE MONDAY
NIGHT THROUGH TUESDAY NIGHT TIME FRAME. THE ECMWF WOULD EVEN IMPLY
SOME LIGHT ACCUMULATING SNOW TUESDAY NIGHT...A COUPLE INCHES
POTENTIALLY. WILL MONITOR THE TREND HERE...BUT WOULD NOT BE
SURPRISED TO SEE THE GFS DRIFT TOWARD THE ECMWF TRACK/EVOLUTION.
ALSO CAN SEE AN INCREASE IN POPS WITH TIME IF THE TREND HOLDS.
OTHERWISE...RIDGING BUILDS IN BEHIND THE EARLY WEEK SHORTWAVE
RESULTING IN MORE IN THE WAY OF SUNSHINE AND WARMING TEMPS.
TEMPERATURES WILL BE BACK TO AROUND NORMALS MID/LATE WEEK. HIGHS ON
FRIDAY SHOULD PUSH WELL INTO THE 40S...WITH 850MB TEMPS FORECAST TO
BE IN THE +3 TO +5 C RANGE.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 656 AM EST SAT MAR 2 2013
MAIN AVIATION CONCERN THE NEXT 24 HOURS HOURS...WILL BE THE SAME
AS THE PREVIOUS 24 HOURS...VARIABLE CEILINGS. CLOUDS WILL VARY
BETWEEN SCT-OVC DOWN WIND OF THE GREAT LAKES IN NORTH TO
NORTHWEST FLOW. IN ADDITION THE CEILING HEIGHTS WILL VARY BETWEEN
MVFR (1800-3000FT) AND VFR (3100-4000FT).
IN GENERAL...CEILINGS WILL BE A BIT LOWER TODAY (MVFR) AND TREND
VFR TONIGHT AS CLOUDS LIFT A BIT AND EVEN TRY TO SCATTER OUT.
&&
.MARINE...
ISSUED AT 956 AM EST SAT MAR 2 2013
THE WAVE MODEL SUGGESTS 3 TO 5 FOOT WAVES INTO SUNDAY MORNING NEAR
AND SOUTH OF HOLLAND SO I ISSUED A SMALL CRAFT ADVISORY TO COVER THIS.
I WILL ADMIT THE WEB CAMS DO NOT LOOK ALL THAT IMPRESSIVE BUT THERE
ARE NORTH WINDS AND THIS IS COLD AIR SO I WENT AHEAD WITH THIS ANYWAY.
ALSO IT MATCHES WHAT IWX HAD OUT.
&&
.HYDROLOGY...
ISSUED AT 315 AM EST SAT MAR 2 2013
THERE IS SOME POTENTIAL FOR INCREASING ICE ON THE MUSKEGON RIVER
THROUGH THE WEEKEND. HOWEVER WATER TEMPERATURES ON THE PINE AND
GRAND RIVERS ARE SEVERAL DEGREES ABOVE FREEZING SO ICE SHOULD BE
DECREASING. STRONGER MARCH SUNSHINE THE NEXT FEW DAYS MAY OFFSET ANY
INCREASE IN ICE AT NIGHT.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST SUNDAY FOR LMZ844>846.
&&
$$
UPDATE...WDM
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...DUKE
AVIATION...DUKE
HYDROLOGY...LAURENS
MARINE...WDM
AREA FORECAST DISCUSSION
NWS HASTINGS NE
622 AM CST SAT MAR 2 2013
.SHORT TERM...(TODAY THROUGH MONDAY NIGHT)
ISSUED AT 403 AM CST SAT MAR 2 2013
TODAY...THERE HAS BEEN SOME EARLY MORNING FOG WEST OF HIGHWAY 281
WITH PATCHY DENSE FOG AT TIMES WEST OF HIGHWAY 183. THE HRRR MODEL
LINGERS THIS FOG ALL THE WAY THROUGH THE ENTIRE MORNING AND
EXPANDS THE FOG EASTWARD IN AREA TO INCLUDE THE HIGHWAY 281
CORRIDOR. THE WIND WILL BE LIGHT...WHICH WILL MAKE IT DIFFICULT
FOR THE FOG TO DISPERSE TOO QUICKLY. HOWEVER...GIVEN THE LIMITED
EXTENT OF THE FOG THUS FAR AS OF 4 AM...BELIEVE THAT THE FOG WILL
NOT BE AS BIG OF A DEAL AS INDICATED BY THE HRRR MODEL.
THEREFORE...WILL BE CALLING FOR ANY FOG TO LIFT BY MID MORNING.
THE WIND WILL GRADUALLY INCREASE FROM THE SOUTH THIS AFTERNOON AND
WARMER AIR ALOFT WILL ALSO WORK IN FROM THE WEST AS AN UPPER RIDGE
BEGINS TO SLIDE EAST INTO THE PLAINS. THEREFORE...EXPECT A WARMER
DAY WITH HIGHS A GOOD DEAL ABOVE FREEZING DESPITE THE SNOW COVER.
HIGHS SHOULD RANGE FROM THE MID 30S ALONG HIGHWAY 81 TO THE MID 40S
WEST OF HIGHWAY 183.
SUNDAY...THIS WILL BE THE NICEST DAY OF THE WEEKEND WITH MUCH OF
THE REMAINING SNOW COVER MELTING. THE WIND WILL REMAIN SOUTHERLY
AND 850MB TEMPERATURES WILL CONTINUE TO CLIMB INTO THE 8-12C RANGE
WITH RIDGING ALOFT.
MONDAY INTO MONDAY NIGHT...A POTENT LITTLE STORM SYSTEM IS
PROJECTED TO TRACK ACROSS THE DAKOTAS AND SHOULD SEND A FAIRLY
SHARP SFC COLD FRONT THROUGH NEBRASKA. HOWEVER...MOST OF THE
PRECIPITATION/SNOW WILL BE WELL NORTH OF OUR FORECAST AREA IN
ASSOCIATION WITH THE UPPER LOW AND SHOULD TRACK SOUTHEAST INTO
MINNESOTA AND EASTERN IOWA. THE LATEST RUN OF THE 00Z ECWMF IS
EVEN FURTHER NORTH WITH THIS SYSTEM THAN PREVIOUS RUNS RESULTING
IN DECREASING POPS ACROSS OUR FORECAST AREA. MOST AREAS WILL FAIL
TO SEE MEASURABLE PRECIPITATION IF THIS NORTHERN TRACK HOLDS TRUE.
IT WILL BE BREEZY BEHIND THE COLD FRONT...BUT EXPECT THE STRONGER
WIND MAY NOT MOVE INTO OUR AREA UNTIL THE UPPER LOW PASSES FURTHER
TO OUR EAST...WHICH WOULD BE ON TUESDAY. TEMPERATURES WILL BE
COOLER ON MONDAY BEHIND THE COLD FRONT.
.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 403 AM CST SAT MAR 2 2013
ALTHOUGH THIS 4-DAY PERIOD DOES NOT APPEAR TO CONTAIN ANY TRULY HIGH
IMPACT WEATHER...AND IS OFFICIALLY PRECIP-FREE IN OUR PRODUCTS AT
LEAST FOR NOW...WILL HAVE TO KEEP AN EYE OUT FOR VARIOUS ELEMENTS
INCLUDING THE POSSIBILITY OF SOME LINGERING FLURRIES/LIGHT SNOW
TUESDAY...POTENTIALLY STRONG NORTH WINDS TUESDAY...AND POTENTIALLY
FAIRLY STRONG SOUTH WINDS BY THURSDAY.
STARTING OFF TUESDAY/TUESDAY NIGHT...UNFORTUNATELY MODEL AGREEMENT
AMONGST THE 00Z ECMWF/GFS/GEM SOLUTIONS LEAVES A BIT TO BE DESIRED.
ON A BASIC SYNOPTIC SCALE ALOFT...ALL 3 MODELS AT LEAST SHOW A
FAIRLY STOUT NORTHWEST-FLOW SHORTWAVE TROUGH DIVING SOUTHEAST FROM A
POSITION IN THE THE NORTHERN OR CENTRAL PLAINS TUESDAY MORNING...TO
THE TENNESSEE VICINITY BY WEDNESDAY MORNING. HOWEVER...GETTING MORE
INTO THE DETAILS...THE GFS/GEM TRACKS THE HEART OF THE 500MB VORT
MAX ACROSS AT LEAST EASTERN IF NOT CENTRAL PORTIONS OF NEB/KS DURING
THE DAY...WHILE THE ECMWF KEEPS THE MAIN FORCING A FEW HUNDRED MILES
FARTHER NORTHEAST OVER SOUTHERN MN/IA. CERTAINLY IF THE FARTHER
SOUTHWEST SOLUTIONS ARE CORRECT...WE MAY VERY WELL NEED SOME
FLURRIES OR MAYBE EVEN A MEASURABLE POP FOR LIGHT SNOW INTRODUCED IN
LATER FORECASTS MAINLY ACROSS THE NORTHEAST 1/2 OF THE CWA FOR
TUESDAY DAYTIME. HOWEVER...GIVEN THAT THIS IS STILL 7 PERIODS OUT
WILL HOLD OFF FOR NOW. OF LIKELY GREATER IMPORTANCE...AND WHAT ALL
OF THESE MODELS SEEM TO AGREE ON...IS THAT TUESDAY IS TRENDING
WINDIER AS THIS AFOREMENTIONED SHORTWAVE PASSES AND SURFACE PRESSURE
RISES RAMP UP IN RESPONSE TO STRONG HIGH PRESSURE NOSING IN FROM THE
NORTH. FOR NOW HAVE RAISED SUSTAINED SPEEDS GENERALLY 5-10 MPH FROM
PREVIOUS FORECAST...GETTING UP IN THE 20-25 MPH RANGE BUT STILL
SOLIDLY 5 MPH SHORT OF ADVISORY CRITERIA. THIS WILL BEAR WATCHING
HOWEVER...AND IF THESE SPEEDS PICK UP MUCH MORE A STRONG WIND
MENTION MAY SOON BE WARRANTED IN THE HAZARDOUS WEATHER OUTLOOK. BY
TUESDAY EVENING...WIND SPEEDS SHOULD SUBSIDE FAIRLY STEADILY AS THE
HIGH PRESSURE AXIS SETTLES INTO THE CENTRAL PLAINS. TEMP-WISE...MADE
ONLY SMALL TWEAKS WITH DAYTIME HIGHS SOMEWHERE IN THE 30S AND TUES
NIGHT LOWS MAINLY IN THE TEENS.
WEDNESDAY/WEDNESDAY NIGHT...THE ECMWF/GFS/GEM ARE IN FAIRLY GOOD
AGREEMENT FOR THIS TIME RANGE IN DEPICTING A BRIEF PERIOD OF
SHORTWAVE RIDGING ALOFT TRANSLATING OVER THE CENTRAL PLAINS IN
ADVANCE OF THE NEXT UPSTREAM OPEN WAVE MAKING INROADS ACROSS THE
WESTERN CONUS. THIS GIVES A RATHER HIGH CONFIDENCE IN A DRY 24
HOURS. WITH THE SURFACE RIDGE AXIS QUICKLY MOVING OFF TO THE EAST
AND HIGH PLAINS SURFACE PRESSURE FALLS COMMENCING TO OUR
EAST...WEDNESDAY SHOULD HAVE SOUTH-SOUTHEAST BREEZES AROUND 15 MPH
OR HIGHER...WITH THESE SPEEDS MAINTAINING THROUGH THE NIGHT.
DESPITE THE SOUTHERLY WIND DIRECTION...NOT SURE HOW STRONG WARMING
WILL BE GIVEN THAT COLD AIR WILL BE RE-CIRCULATED AROUND THE
DEPARTING RIDGE AXIS TO SOME EXTENT. AS A RESULT...ACTUALLY NUDGED
DOWN HIGHS A FEW DEGREES ALL AREAS...BUT STILL INTO THE 40S EXCEPT
UPPER 30S FAR NORTHEAST. WEDNESDAY NIGHT LOW TEMPS SHOULD AVERAGE
AROUND 10 DEGREES WARMER THAN TUESDAY NIGHT WITH MAINLY UPPER 20S TO
NEAR 30.
THURSDAY/THURSDAY NIGHT...CONFIDENCE STARTS TO WANE A LITTLE BIT
THAT THIS 24 HOURS WILL TRULY STAY PRECIP-FREE...AS THE
ECMWF/GFS/GEM START TO DIVERGE REGARDING HOW THE WESTERN CONUS
TROUGH IS HANDLED. WHILE THE ECMWF/GFS TRACK A LEAD MID LEVEL
SHORTWAVE MAINLY TO OUR NORTH INTO THE DAKOTAS DURING THIS
TIME...THE GEM SOLUTION TAKES THIS LEAD WAVE RIGHT INTO WESTERN
NEB/KS BY THURS EVENING...SUGGESTING SOME POSSIBLE RAIN SHOWER
POTENTIAL. FOR NOW WILL MAINTAIN THE DRY COURSE. AT THE
SURFACE...SOUTHERLY WINDS WILL LIKELY RAMP UP ANOTHER NOTCH IN A
TIGHTENED PRESSURE GRADIENT...AND ALTHOUGH THE OFFICIAL GRIDS ONLY
DEPICT AROUND 20 MPH SUSTAINED SPEEDS AT THIS TIME...ACTUAL SPEEDS
COULD ULTIMATELY PROVE TO BE AT LEAST 5-10 MPH HIGHER IF TRENDS
HOLD. TEMP-WISE...THURSDAY STILL LOOKS LIKE THE LIKELY CANDIDATE FOR
THE WARMEST DAY OF THE WEEK...ALTHOUGH EVEN THE DEGREE OF WARMING
ABOVE THE SURFACE AT 850MB IS NOT SHOWING GREAT MODEL AGREEMENT.
GIVEN THIS UNCERTAINTY...OPTED TO MAKE NO CHANGES WHATSOEVER TO
PREVIOUS HIGHS...PUSHING THE ENTIRE CWA SOMEWHERE INTO THE
50S...WITH FAR WESTERN COUNTIES MAYBE CRACKING 60. PER THE
ECMWF/GFS...A COLD FRONT THEN STARTS SAGGING SOUTHWARD INTO THE CWA
THURSDAY NIGHT.
FRIDAY...THE GENERAL THEME PER THE ECMWF/GFS IS THAT BROAD SOUTHWEST
FLOW ALOFT PERSISTS OVER THE CENTRAL PLAINS...DOWNSTREAM FROM A
LARGE TROUGH/CLOSED LOW DIGGING INTO THE SOUTHERN CA/AZ REGION.
THERE ARE SUGGESTIONS THAT SOME RAIN SHOWERS COULD BREAK OUT MAINLY
LATE IN THE DAY IN PARTS OF THE CWA PER THE ECMWF...BUT WILL HOLD
POPS IN SILENT TERRITORY FOR NOW...WITH POTENTIALLY MUCH BETTER
PRECIP CHANCES ENTERING THE PICTURE JUST BEYOND THE OFFICIAL
FORECAST PERIODS FOR FRI NIGHT-SATURDAY. HOWEVER...EVEN THIS WEEKEND
PRECIP CHANCE IS IN QUESTION REGARDING WHETHER IT SQUARELY AFFECTS
THE CWA...OR TRENDS MORE TO OUR SOUTH. TEMP-WISE...FRIDAY CERTAINLY
LOOKS COOLER THAN THURSDAY WITH STEADY NORTHEAST WINDS IN PLACE
BEHIND A COLD FRONT...JUST A MATTER OF HOW MUCH COOLER. FOR NOW WILL
RUN WITH A RANGE FROM MID 40S NORTH TO LOW 50S SOUTH...WHICH IS JUST
A TOUCH COOLER THAN PREVIOUS FORECAST.
&&
.AVIATION...(FOR THE 12Z KGRI TAF THROUGH 12Z SUNDAY MORNING)
ISSUED AT 604 AM CST SAT MAR 2 2013
ALTHOUGH THE MAJORITY OF THE PERIOD IS EXPECTED TO FEATURE VFR
CONDITIONS...CONFIDENCE ESPECIALLY REGARDING VISIBILITY TRENDS IS
NOT OVERLY HIGH. STARTING OUT EARLY THIS MORNING...HAVE BEEN WAITING
ALL NIGHT FOR THE POSSIBLE ONSET OF FOG THAT HAS NOT SET IN...AND
NOW THAT INCREASING MID LEVEL CLOUDS ARE MOVING IN...FOG IS
SEEMING LESS AND LESS LIKELY. HOWEVER...JUST TO HINT AT THE
POSSIBILITY OF LIMITED FOG DEVELOPMENT HAVE INDICATED SOME 6SM BR
VISIBILITY THROUGH 16Z. OTHERWISE...EXPECT PLENTY OF VFR MID-
CLOUDS DURING THE DAYTIME HOURS...AS BREEZES TOP OUT AROUND 10KT
FROM THE SOUTH-SOUTHWEST. A FEW SNOW FLURRIES ARE NOT EVEN OUT OF
THE QUESTION THIS MORNING...BUT THIS DOES NOT SEEM WORTHY OF A
MENTION. TURNING TO SATURDAY NIGHT...CONFIDENCE IN VISIBILITY
TRENDS AGAIN LOWERS CONSIDERABLY...AS VARIOUS MODEL/GUIDANCE
SOLUTIONS OFFER DIFFERING OPINIONS ON FOG DEVELOPMENT. ON ONE
HAND...AT LEAST LIMITED SNOW MELT TODAY WOULD FAVOR A MORE ROBUST
ONSET OF FOG...BUT A LIGHT BUT STEADY SOUTHWESTERLY BREEZE IS
NORMALLY NOT CONDUCIVE FOR MAJOR FOG ISSUES. FOR THE TIME
BEING...WILL INTRODUCE PREVAILING MVFR VSBY AT 04Z AND KEEP IT
GOING THROUGH THE END OF THE PERIOD...BUT PLEASE ALLOW FOR PLENTY
OF WIGGLE ROOM ON BOTH THE OPTIMISTIC AND PESSIMISTIC SIDE OF THIS
VALUE.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...WESELY
LONG TERM...PFANNKUCH
AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
426 AM CST SAT MAR 2 2013
.SHORT TERM...(TODAY THROUGH MONDAY NIGHT)
ISSUED AT 403 AM CST SAT MAR 2 2013
TODAY...THERE HAS BEEN SOME EARLY MORNING FOG WEST OF HIGHWAY 281
WITH PATCHY DENSE FOG AT TIMES WEST OF HIGHWAY 183. THE HRRR MODEL
LINGERS THIS FOG ALL THE WAY THROUGH THE ENTIRE MORNING AND
EXPANDS THE FOG EASTWARD IN AREA TO INCLUDE THE HIGHWAY 281
CORRIDOR. THE WIND WILL BE LIGHT...WHICH WILL MAKE IT DIFFICULT
FOR THE FOG TO DISPERSE TOO QUICKLY. HOWEVER...GIVEN THE LIMITED
EXTENT OF THE FOG THUS FAR AS OF 4 AM...BELIEVE THAT THE FOG WILL
NOT BE AS BIG OF A DEAL AS INDICATED BY THE HRRR MODEL.
THEREFORE...WILL BE CALLING FOR ANY FOG TO LIFT BY MID MORNING.
THE WIND WILL GRADUALLY INCREASE FROM THE SOUTH THIS AFTERNOON AND
WARMER AIR ALOFT WILL ALSO WORK IN FROM THE WEST AS AN UPPER RIDGE
BEGINS TO SLIDE EAST INTO THE PLAINS. THEREFORE...EXPECT A WARMER
DAY WITH HIGHS A GOOD DEAL ABOVE FREEZING DESPITE THE SNOW COVER.
HIGHS SHOULD RANGE FROM THE MID 30S ALONG HIGHWAY 81 TO THE MID 40S
WEST OF HIGHWAY 183.
SUNDAY...THIS WILL BE THE NICEST DAY OF THE WEEKEND WITH MUCH OF
THE REMAINING SNOW COVER MELTING. THE WIND WILL REMAIN SOUTHERLY
AND 850MB TEMPERATURES WILL CONTINUE TO CLIMB INTO THE 8-12C RANGE
WITH RIDGING ALOFT.
MONDAY INTO MONDAY NIGHT...A POTENT LITTLE STORM SYSTEM IS
PROJECTED TO TRACK ACROSS THE DAKOTAS AND SHOULD SEND A FAIRLY
SHARP SFC COLD FRONT THROUGH NEBRASKA. HOWEVER...MOST OF THE
PRECIPITATION/SNOW WILL BE WELL NORTH OF OUR FORECAST AREA IN
ASSOCIATION WITH THE UPPER LOW AND SHOULD TRACK SOUTHEAST INTO
MINNESOTA AND EASTERN IOWA. THE LATEST RUN OF THE 00Z ECWMF IS
EVEN FURTHER NORTH WITH THIS SYSTEM THAN PREVIOUS RUNS RESULTING
IN DECREASING POPS ACROSS OUR FORECAST AREA. MOST AREAS WILL FAIL
TO SEE MEASURABLE PRECIPITATION IF THIS NORTHERN TRACK HOLDS TRUE.
IT WILL BE BREEZY BEHIND THE COLD FRONT...BUT EXPECT THE STRONGER
WIND MAY NOT MOVE INTO OUR AREA UNTIL THE UPPER LOW PASSES FURTHER
TO OUR EAST...WHICH WOULD BE ON TUESDAY. TEMPERATURES WILL BE
COOLER ON MONDAY BEHIND THE COLD FRONT.
.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 403 AM CST SAT MAR 2 2013
ALTHOUGH THIS 4-DAY PERIOD DOES
NOT LOOK TO CONTAIN ANY TRULY HIGH IMPACT WEATHER...AND IS
OFFICIALLY PRECIP-FREE IN OUR PRODUCTS AT LEAST FOR NOW...WILL HAVE TO
KEEP AN EYE OUT FOR VARIOUS ELEMENTS INCLUDING THE POSSIBILITY OF SOME
LINGERING FLURRIES/LIGHT SNOW TUESDAY...POTENTIALLY STRONG
NORTH WINDS TUESDAY...AND POTENTIALLY FAIRLY STRONG SOUTH WINDS BY
THURSDAY.
STARTING OFF TUESDAY/TUESDAY NIGHT...UNFORTUNATELY MODEL AGREEMENT
AMONGST THE 00Z ECMWF/GFS/GEM SOLUTIONS LEAVES A BIT TO BE DESIRED.
ON A BASIC SYNOPTIC SCALE ALOFT...ALL 3 MODELS AT LEAST SHOW A
FAIRLY STOUT NORTHWEST-FLOW SHORTWAVE TROUGH DIVING SOUTHEAST FROM A
POSITION IN THE THE NORTHERN OR CENTRAL PLAINS TUESDAY MORNING...TO
THE TENNESSEE VICINITY BY WEDNESDAY MORNING. HOWEVER...GETTING MORE
INTO THE DETAILS...THE GFS/GEM TRACKS THE HEART OF THE 500MB VORT
MAX ACROSS AT LEAST EASTERN IF NOT CENTRAL PORTIONS OF NEB/KS DURING
THE DAY...WHILE THE ECMWF KEEPS THE MAIN FORCING A FEW HUNDRED MILES
FARTHER NORTHEAST OVER SOUTHERN MN/IA. CERTAINLY IF THE FARTHER
SOUTHWEST SOLUTIONS ARE CORRECT...WE MAY VERY WELL NEED SOME
FLURRIES OR MAYBE EVEN A MEASURABLE POP FOR LIGHT SNOW INTRODUCED IN
LATER FORECASTS MAINLY ACROSS THE NORTHEAST 1/2 OF THE CWA FOR
TUESDAY DAYTIME. HOWEVER...GIVEN THAT THIS IS STILL 7 PERIODS OUT
WILL HOLD OFF FOR NOW. OF LIKELY GREATER IMPORTANCE...AND WHAT ALL
OF THESE MODELS SEEM TO AGREE ON...IS THAT TUESDAY IS TRENDING
WINDIER AS THIS AFOREMENTIONED SHORTWAVE PASSES AND SURFACE PRESSURE
RISES RAMP UP IN RESPONSE TO STRONG HIGH PRESSURE NOSING IN FROM THE
NORTH. FOR NOW HAVE RAISED SUSTAINED SPEEDS GENERALLY 5-10 MPH FROM
PREVIOUS FORECAST...GETTING UP IN THE 20-25 MPH RANGE BUT STILL
SOLIDLY 5 MPH SHORT OF ADVISORY CRITERIA. THIS WILL BEAR WATCHING
HOWEVER...AND IF THESE SPEEDS PICK UP MUCH MORE A STRONG WIND
MENTION MAY SOON BE WARRANTED IN THE HAZARDOUS WEATHER OUTLOOK. BY
TUESDAY EVENING...WIND SPEEDS SHOULD SUBSIDE FAIRLY STEADILY AS THE
HIGH PRESSURE AXIS SETTLES INTO THE CENTRAL PLAINS. TEMP-WISE...MADE
ONLY SMALL TWEAKS WITH DAYTIME HIGHS SOMEWHERE IN THE 30S AND TUES
NIGHT LOWS MAINLY IN THE TEENS.
WEDNESDAY/WEDNESDAY NIGHT...THE ECMWF/GFS/GEM ARE IN FAIRLY GOOD
AGREEMENT FOR THIS TIME RANGE IN DEPICTING A BRIEF PERIOD OF
SHORTWAVE RIDGING ALOFT TRANSLATING OVER THE CENTRAL PLAINS IN
ADVANCE OF THE NEXT UPSTREAM OPEN WAVE MAKING INROADS ACROSS THE
WESTERN CONUS. THIS GIVES A RATHER HIGH CONFIDENCE IN A DRY 24
HOURS. WITH THE SURFACE RIDGE AXIS QUICKLY MOVING OFF TO THE EAST
AND HIGH PLAINS SURFACE PRESSURE FALLS COMMENCING TO OUR
EAST...WEDNESDAY SHOULD HAVE SOUTH-SOUTHEAST BREEZES AROUND 15 MPH
OR HIGHER...WITH THESE SPEEDS MAINTAINING THROUGH THE NIGHT.
DESPITE THE SOUTHERLY WIND DIRECTION...NOT SURE HOW STRONG WARMING
WILL BE GIVEN THAT COLD AIR WILL BE RE-CIRCULATED AROUND THE
DEPARTING RIDGE AXIS TO SOME EXTENT. AS A RESULT...ACTUALLY NUDGED
DOWN HIGHS A FEW DEGREES ALL AREAS...BUT STILL INTO THE 40S EXCEPT
UPPER 30S FAR NORTHEAST. WEDNESDAY NIGHT LOW TEMPS SHOULD AVERAGE
AROUND 10 DEGREES WARMER THAN TUESDAY NIGHT WITH MAINLY UPPER 20S TO
NEAR 30.
THURSDAY/THURSDAY NIGHT...CONFIDENCE STARTS TO WANE A LITTLE BIT
THAT THIS 24 HOURS WILL TRULY STAY PRECIP-FREE...AS THE
ECMWF/GFS/GEM START TO DIVERGE REGARDING HOW THE WESTERN CONUS
TROUGH IS HANDLED. WHILE THE ECMWF/GFS TRACK A LEAD MID LEVEL
SHORTWAVE MAINLY TO OUR NORTH INTO THE DAKOTAS DURING THIS
TIME...THE GEM SOLUTION TAKES THIS LEAD WAVE RIGHT INTO WESTERN
NEB/KS BY THURS EVENING...SUGGESTING SOME POSSIBLE RAIN SHOWER
POTENTIAL. FOR NOW WILL MAINTAIN THE DRY COURSE. AT THE
SURFACE...SOUTHERLY WINDS WILL LIKELY RAMP UP ANOTHER NOTCH IN A
TIGHTENED PRESSURE GRADIENT...AND ALTHOUGH THE OFFICIAL GRIDS ONLY
DEPICT AROUND 20 MPH SUSTAINED SPEEDS AT THIS TIME...ACTUAL SPEEDS
COULD ULTIMATELY PROVE TO BE AT LEAST 5-10 MPH HIGHER IF TRENDS
HOLD. TEMP-WISE...THURSDAY STILL LOOKS LIKE THE LIKELY CANDIDATE FOR
THE WARMEST DAY OF THE WEEK...ALTHOUGH EVEN THE DEGREE OF WARMING
ABOVE THE SURFACE AT 850MB IS NOT SHOWING GREAT MODEL AGREEMENT.
GIVEN THIS UNCERTAINTY...OPTED TO MAKE NO CHANGES WHATSOEVER TO
PREVIOUS HIGHS...PUSHING THE ENTIRE CWA SOMEWHERE INTO THE
50S...WITH FAR WESTERN COUNTIES MAYBE CRACKING 60. PER THE
ECMWF/GFS...A COLD FRONT THEN STARTS SAGGING SOUTHWARD INTO THE CWA
THURSDAY NIGHT.
FRIDAY...THE GENERAL THEME PER THE ECMWF/GFS IS THAT BROAD SOUTHWEST
FLOW ALOFT PERSISTS OVER THE CENTRAL PLAINS...DOWNSTREAM FROM A
LARGE TROUGH/CLOSED LOW DIGGING INTO THE SOUTHERN CA/AZ REGION.
THERE ARE SUGGESTIONS THAT SOME RAIN SHOWERS COULD BREAK OUT MAINLY
LATE IN THE DAY IN PARTS OF THE CWA PER THE ECMWF...BUT WILL HOLD
POPS IN SILENT TERRITORY FOR NOW...WITH POTENTIALLY MUCH BETTER
PRECIP CHANCES ENTERING THE PICTURE JUST BEYOND THE OFFICIAL
FORECAST PERIODS FOR FRI NIGHT-SATURDAY. HOWEVER...EVEN THIS WEEKEND
PRECIP CHANCE IS IN QUESTION REGARDING WHETHER IT SQUARELY AFFECTS
THE CWA...OR TRENDS MORE TO OUR SOUTH. TEMP-WISE...FRIDAY CERTAINLY
LOOKS COOLER THAN THURSDAY WITH STEADY NORTHEAST WINDS IN PLACE
BEHIND A COLD FRONT...JUST A MATTER OF HOW MUCH COOLER. FOR NOW WILL
RUN WITH A RANGE FROM MID 40S NORTH TO LOW 50S SOUTH...WHICH IS JUST
A TOUCH COOLER THAN PREVIOUS FORECAST.
&&
.AVIATION...(FOR THE 06Z KGRI TAF THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1216 AM CST SAT MAR 2 2013
ALTHOUGH EXPECT PREVAILING VFR CONDITIONS THROUGH THE MAJORITY OF
THE PERIOD...CONFIDENCE ESPECIALLY REGARDING VISIBILITY TRENDS
OVER THE NEXT 6-9 HOURS IS ADMITTEDLY SHAKY. AT LEAST SO FAR
TONIGHT...EARLIER INDICATIONS OF FAIRLY WIDESPREAD IFR TO LIFR
VISIBILITY/CEILING IN FOG HAS NOT COME TO FRUITION...AND CONSENSUS
OF LATEST MODELS SUGGESTS THAT KGRI MAY REMAIN JUST FAR ENOUGH
EAST TO AVOID A MAJOR DEGRADATION IN CONDITIONS. THAT BEING
SAID...GIVEN GENERALLY LIGHT/VARIABLE BREEZES WILL AT LEAST
MAINTAIN SEVERAL HOURS OF MVFR VISIBILITY POTENTIAL...AND AMEND
SHORT TERM TRENDS AS NEEDED. ASSUMING MAJOR FOG PROBLEMS DO NOT
ARISE...EXPECT ANY CEILINGS TO REMAIN VFR THROUGH THE
PERIOD...ALTHOUGH A BROKEN VFR DECK BELOW 10 THOUSAND FEET IS
POSSIBLE FOR PART OF THE DAY. ALTHOUGH SOME MODELS ARE ALREADY
INDICATING ADDITIONAL POTENTIAL FOR FOG TOWARD THE END OF THE
PERIOD MAINLY AFTER 03Z SATURDAY EVENING...CONFIDENCE IS NOT HIGH
IN THIS SCENARIO GIVEN SHAKY MODEL PERFORMANCE IN THE
NEAR-TERM...SO WILL DEFER TO LATER FORECASTS TO POSSIBLY INSERT
SATURDAY NIGHT FOG. SURFACE WINDS WILL NOT BE MUCH OF AN ISSUE
DURING THE PERIOD...WITH SOUTH-SOUTHWEST SPEEDS ONLY TOPPING OUT
AROUND 10KT DURING THE AFTERNOON INTO SATURDAY EVENING.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...WESELY
LONG TERM...PFANNKUCH
AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
957 AM EST SAT MAR 2 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL CROSS THE REGION FROM THE WEST
TODAY. LOW PRESSURE WILL MOVE OFF THE EAST COAST ON SUNDAY...WITH A
RETURN OF BRIEF HIGH PRESSURE THROUGH MONDAY. A LOW PRESSURE SYSTEM
DEVELOPING OVER THE MID MISSISSIPPI RIVER VALLEY ON TUESDAY WILL
CROSS THE AREA ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM...AS THE CENTER OF A COMPACT 500 MB LOW CROSSES THE
CWFA THIS MORNING...PRECIP BANDS HAVE EXPANDED TO ITS EAST ACRS THE
SRN NC PIEDMONT AND MUCH OF THE UPSTATE. I BUMPED UP THE POPS TO
LIKELY IN THESE AREAS. AS THE PRECIP RATES INCREASE...RAIN HAS BEEN
MIXING WITH AND CHANGING OVER TO SNOW. A FEW BANDS HAVE BECOME
SOMEWHAT INTENSE IN THE CHARLOTTE METRO AREA. FORTUNATELY...GROUND
TEMPS ARE WARM...AND THE BANDS ARE SMALL AND TRANSITORY. A LOOK AT
AREA WEBCAMS SHOW SNOW STILL NOT STICKING IN MOST SPOTS. SO WILL
HANDLE THIS WITH AN SPS...RATHER THAN A WSW. AS FOR THE CURRENT
WSW...THAT AREA IS IN THE NVA SIDE OF THE VORTMAX...AND CLEARING IS
REALLY EXPANDING ON VIS SAT IMAGERY. I WILL ENTERTAIN CUTTING THE
WINTER WX ADV BACK WITH THE NEXT UPDATE GIVEN TRENDS.
ONE REASON I DID NOT WITH THIS UPDATE WAS THAT HIGH RES MODELS STILL
IN AGREEMENT ON ENUF CONVECTIVE INSTBY FOR SHOWERS TO DEVELOP ALONG
THE BLUE RIDGE...WITH ENUF CONVERGENCE TO HOLD TOGETHER AS THEY
TRACK E/SE ACRS THE PIEDMONT THIS AFTN. THE CLEARING WILL HELP WITH
DESTABILIZATION...BUT WILL ALSO WARM THE BL. SO THERE IS UNCERTAINTY
ON HOW MUCH OF THE PRECIP WILL FALL AS SNOW...EVEN IN SOME OF THE
HIGHER ELEVATIONS OF THE SRN NC MTNS AND THE GA/SC MTNS. I WILL
REASSESS THE GUIDANCE AND TRENDS AND MAKE A DECISION WITH THE NEXT
UPDATE BEFORE NOON.
PREVIOUS DISCUSSION...
AS OF 345 AM...LATEST IR SATELLITE INDICATES COLD TOP CLOUDS RAPIDLY
EXPANDING ACROSS THE SOUTHERN AND CENTRAL NC MTNS...WITH A BAND OF
-22C OR COLDER CLOUDS ACROSS EXTREME NE GA AND THE SC MTNS. RADAR
RETURNS HAVE INCREASED EARLY THIS MORNING...ESPECIALLY ACROSS NE
GA...SC MTNS...AND THE CENTRAL MOUNTAINS...WITH SEVERAL AREAS OF DBZ
AROUND 30 DBZ. DUAL POL PRODUCTS INDICATE THAT THE MELTING LAYER HAS
LOWERED TO AROUND 1 KFT. BASED ON THE LATEST TRENDS...I WILL ADD THE
CENTRAL NC MTNS FROM MACON TO TRANSYLVANIA...EXTREME NE GA FROM
FRANKLIN TO RABUN...AND OCONEE AND PICKENS MTNS TO THE WINTER
WEATHER ADVISORY UNTIL 6 PM.
SHOWERS ARE FORECAST TO SPREAD SLOWLY EAST ACROSS THE FOOTHILLS AND
PIEDMONT THIS MORNING. THE EASTWARD MOVEMENT OF THE PRECIPITATION
WILL BE A RESULT OF THE SPREADING OF H5 15 TO 20 MB/HR VERTICAL
VELOCITIES ALONG AND AHEAD OF THE CLOSED LOW. THE SYNOPTIC SCALE
FORCING SHOULD PEAK AROUND 12Z...THEN GRADUALLY WEAKENING THROUGH
THE REST OF THE DAYLIGHT HOURS. FORECAST SOUNDINGS ACROSS THE
FOOTHILLS AND PIEDMONT...INCLUDING PARTIAL THICKNESSES...SHOULD
SUPPORT SN ACROSS THE MTNS...RASN ACROSS THE FOOTHILLS...WITH RA
ACROSS THE PIEDMONT. HOWEVER...STRONGER SHOWERS SHOULD RESULT IN
PURE SN THIS MORNING...EVEN OVER THE PIEDMONT. BASED ON A BLEND OF
HPC...WRFARW...AND RUC QPF...I WILL FORECAST 2-3 INCHES ACROSS THE
TN BORDER CO...AND THE SOUTHERN AND CENTRAL MTNS...WITH 4 INCHES
POSSIBLE IN SPOTS ALONG THE RIDGELINE OF THE SMOKIES. EXTREME NE GA
MAY SEE 0.5 TO 1.4 INCHES...WITH ACROSS AN INCH ACROSS OCONEE AND
PICKENS MTNS. AREAS EAST...INCLUDING THE GSP AND CLT METRO AREAS MAY
SEE AROUND 0.1-0.2 INCHES. HIGH TEMPERATURES ARE FORECAST TO RANGE
FROM THE 30S ACROSS THE MTNS TO THE LOW TO MID 40S EAST.
LATE THIS AFTERNOON...SREF INDICATES THAT MUCAPE WILL LIKELY POOL TO
AT LEAST 50 J/KG ACROSS THE FOOTHILLS AND PIEDMONT. AS THE H5 TROF
AXIS PIVOTS EAST OF THE MTNS. WEAKLY CONVECTIVE SHOWERS ARE EXPECTED
TO DEVELOP ACROSS THE FOOTHILLS. CONVECTIVE ALLOWING GUIDANCE
INDICATES THAT THE SHOWERS MAINLY ORGANIZE INTO A LINE OR A CLUSTER.
I WILL TIME THE CONVECTION EAST ACROSS THE EASTERN HALF OF THE
FORECAST AREA THIS AFTERNOON...REACHING KGSP AT 19Z...AND CLT BY 22Z.
TONIGHT...NWFS WILL GRADUALLY FADE ALONG THE TN BORDER THIS
EVENING...ENDING DURING THE LATE NIGHT HOURS. WINDS WILL REMAIN FROM
THE NW...RANGING FROM 5 TO 10 KTS. CLOUD COVER WILL DECREASE THROUGH
THE NIGHT...ESPECIALLY EAST OF THE MTNS. LOW TEMPERATURES SHOULD
RANGE FROM THE L20S ACROSS THE MTNS TO THE MID TO U20S EAST.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM SATURDAY...ONE FINAL SHORTWAVE WILL DROP INTO THE EAST
COAST TROUGH AXIS ON SUNDAY BEFORE IT DEPARTS...BRINGING MAINLY
CHANNELED VORTICITY FROM THE WRN GREAT LAKES TO THE WRN CAROLINAS.
DEEP LAYER MOISTURE WILL BE ABSENT WITH THIS FEATURE...BUT LINGERING
LOW LEVEL NW UPSLOPE FLOW MOISTURE MAY PERMIT ISOLATED SNOW SHOWERS
TO LINGER ALONG THE TN BORDER INTO THE MORNING HOURS BEFORE DRYING
UP. CHILLY THICKNESSES...AND LINGERING PATCHY MID AND HIGH
CLOUDS...WILL KEEP TEMPERATURES SEVERAL CATEGORIES BELOW NORMAL.
A FLAT UPPER RIDGE WILL CROSS THE AREA MONDAY THROUGH MONDAY NIGHT.
PLENTY OF HIGH LEVEL CLOUDS SHOULD TOP THE RIDGE AXIS IN THE SWIFT
WESTERLY FLOW ALOFT DURING THIS PERIOD. THE AIRMASS SHOULD MODIFY
ENOUGH TO PUSH MAX TEMPERATURES BACK INTO THE 50S THROUGHOUT MON
AFTN...EXCEPT 40S ALONG THE HIGHER MOUNTAINS.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 310 AM SATURDAY...THERE IS GENERALLY GOOD CONSENSUS AMONG THE
VARIOUS MODELS ON A DEEPENING LOW PRES SYSTEM MOVING SE THROUGH THE
MIDWEST ON TUE...CROSSING THE FORECAST AREA ON WED...THEN DEEPENING
FURTHER ALONG THE IMMEDIATE E COAST WED NIGHT. HOWEVER...DIFFERENCES
AMONG THE MODELS IN THE SFC LOW AND 850 MB LOW CENTER TRACKS WILL
PLAY A CRITICAL ROLE IN PRECIPITATION TYPE AND AMOUNT. THERE IS GOOD
AGREEMENT THAT ISENTROPIC LIFT AHEAD OF THE SYSTEM WILL RETURN TO
THE REGION LATE MON NIGHT...WITH THE BEST BELT OF UPGLIDE ACROSS THE
HEART OF THE AREA MIDDAY TUE. PROFILES SUPPORT MAINLY RAIN ON THE
WARM ADVECTION SIDE OF THE SYSTEM...BUT WITH FREEZING RAIN POSSIBLE
IN SPOTS AT ONSET...ESPECIALLY ACROSS THE NRN NC MOUNTAINS.
THICKNESSES SHOULD CRASH WED MORNING AS THE COLD LOW PRESSURE SYSTEM
TRANSITIONS TOWARD THE COAST. QG FORCING SHOULD BE PLENTIFUL JUST
AHEAD OF THE LOW TUE NIGHT AND WED MORNING...WITH SOME DEGREE OF
FRONTOGENESIS AND DEFORMATION ZONE FORCING TRAILING THE DEPARTING
LOW THROUGH THE PIEDMONT WED AFTN/EVENING. VERY STEEP LAPSE RATES
UNDER THE PASSING UPPER LOW SHOULD SUPPORT AT LEAST ISOLD TO SCT
THUNDERSTORMS/THUNDERSNOW AT TIMES. CONFIDENCE IS HIGHEST ON
SIGNIFICANT ACCUMULATING SNOW OVER THE MTNS AND ALSO NC FOOTHILL AND
PIEDMONT LOCATIONS ALONG AND NORTH OF INTERSTATE 40. MORE OF A
RAIN/SNOW MIX IS EXPECTED TOWARD THE INTERSTATE 85 CORRIDOR AND
POINTS SOUTH...BUT LIKELY ENDING AS SNOW SHOWERS. WILL CONTINUE THE
HWO MENTION FOR THIS POTENTIALLY SIGNIFICANT WINTER STORM SYSTEM.
A WARMER AND DRY RIDGE PATTERN WILL RETURN THU THROUGH FRI...WITH
TEMPERATURES SLOWLY REBOUNDING TO WITHIN 5 DEGREES OF NORMAL.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...THE 12Z TAF WILL BEGIN WITH VFR CONDITIONS AND A LIGHT NE
WIND. CEILING BASES SHOULD GRADUALLY LOWER THROUGH MID MORNING AS
SYNOPTIC SCALE FORCING SPREADS ACROSS THE PIEDMONT. BETWEEN 12Z TO
18Z...MID LEVEL FORCING SHOULD PEAK ACROSS THE TERMINAL...THEN
WEAKEN THROUGH THE AFTERNOON HOURS. NAM FORECAST SOUNDINGS SUPPORTS
CEILINGS FALLING TO LVFR BETWEEN 12Z TO 15Z. THE ARRIVAL OF THE DEEP
FORCING AT DAY BREAK MAY YIELD ONE OF THE HIGHEST CHCS FOR PRECIP
DURING THE PERIOD. ANOTHER BAND OF RASN MAY PASS ACROSS THE TERMINAL
BETWEEN 22Z TO 24Z WITH THE PUSH OF THE DRY SLOT. ONCE THE DRY SLOT
ARRIVES...CEILINGS WILL LIFT AND STEADY NW WINDS SHOULD REMAIN
THROUGH 12Z SUN. I WOULD EXPECT THAT ACCUMULATING SNOW IS POSSIBLE
THIS MORNING AND AGAIN LATE THIS AFTERNOON...ACCUMS WILL LIKELY
REMAIN LESS THAN A HALF INCH.
ELSEWHERE...TIMING SIMILAR TO CLT. HOWEVER...KGSP...KGMU...AND KHKY
SHOULD SEE WINDOWS OF MVFR CEILINGS DEVELOP BETWEEN 12 TO 15Z...BUT
DOWNSLOPE FLOW SHOULD SUPPORT VFR BY MID MORNING. ALL AREAS WILL SEE
THE POTENTIAL FOR LIGHT ACCUMULATING SNOW THIS MORNING....BEST CHC
BETWEEN 12Z TO 16Z. HOWEVER...THE FORMATION OF A WEAKLY CONVECTIVE
BAND THIS AFTERNOON WILL NEED CLOSE ATTENTION.
OUTLOOK...SNOW SHOWERS WILL DIMINSIHING THE TENNESSEE BORDER ON
SUNDAY. MONDAY SHOULD REMAIN VFR ACROSS THE FORECAST AREA.
ANOTHER LOW PRESSURE SYSTEM WILL SPREAD LLVL MOISTURE AND
PRECIPITATION ACROSS THE REGION TUESDAY AND WEDNESDAY MORNING.
CONFIDENCE TABLE...
15-21Z 21-03Z 03-09Z 09-15Z
KCLT HIGH 89% HIGH 98% HIGH 100% HIGH 100%
KGSP HIGH 97% HIGH 100% HIGH 100% HIGH 100%
KAVL HIGH 95% HIGH 100% HIGH 100% HIGH 100%
KHKY HIGH 94% HIGH 100% HIGH 100% HIGH 100%
KGMU HIGH 94% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 92% HIGH 100% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR GAZ010-
017-018-026.
NC...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ033-
048>052-058-059-062>064.
SC...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR SCZ001-
002-004.
&&
$$
SYNOPSIS...HG
NEAR TERM...ARK/NED
SHORT TERM...HG
LONG TERM...HG
AVIATION...NED
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
655 AM EST SAT MAR 2 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL CROSS THE REGION FROM THE WEST
TODAY. LOW PRESSURE WILL MOVE OFF THE EAST COAST ON SUNDAY...WITH A
RETURN OF BRIEF HIGH PRESSURE THROUGH MONDAY. A LOW PRESSURE SYSTEM
DEVELOPING OVER THE MID MISSISSIPPI RIVER VALLEY ON TUESDAY WILL
CROSS THE AREA ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 645 AM...RECENT RADAR RETURNS HAVE TRENDED HIGHER ACROSS THE
NC NRN PIEDMONT. I WILL UPDATE THE FORECAST TO ADJUST POP TRENDS TO
RECENT RADAR IMAGES AND SFC OBS. IN ADDITION...I WILL REDUCE THE
MENTION OF SN ACROSS THE FOOTHILLS AND PIEDMONT EARLY THIS
MORNING...MIXING TO SNOW LATER THIS MORNING.
AS OF 345 AM...LATEST IR SATELLITE INDICATES COLD TOP CLOUDS RAPIDLY
EXPANDING ACROSS THE SOUTHERN AND CENTRAL NC MTNS...WITH A BAND OF
-22C OR COLDER CLOUDS ACROSS EXTREME NE GA AND THE SC MTNS. RADAR
RETURNS HAVE INCREASED EARLY THIS MORNING...ESPECIALLY ACROSS NE
GA...SC MTNS...AND THE CENTRAL MOUNTAINS...WITH SEVERAL AREAS OF DBZ
AROUND 30 DBZ. DUAL POL PRODUCTS INDICATE THAT THE MELTING LAYER HAS
LOWERED TO AROUND 1 KFT. BASED ON THE LATEST TRENDS...I WILL ADD THE
CENTRAL NC MTNS FROM MACON TO TRANSYLVANIA...EXTREME NE GA FROM
FRANKLIN TO RABUN...AND OCONEE AND PICKENS MTNS TO THE WINTER
WEATHER ADVISORY UNTIL 6 PM.
SHOWERS ARE FORECAST TO SPREAD SLOWLY EAST ACROSS THE FOOTHILLS AND
PIEDMONT THIS MORNING. THE EASTWARD MOVEMENT OF THE PRECIPITATION
WILL BE A RESULT OF THE SPREADING OF H5 15 TO 20 MB/HR VERTICAL
VELOCITIES ALONG AND AHEAD OF THE CLOSED LOW. THE SYNOPTIC SCALE
FORCING SHOULD PEAK AROUND 12Z...THEN GRADUALLY WEAKENING THROUGH
THE REST OF THE DAYLIGHT HOURS. FORECAST SOUNDINGS ACROSS THE
FOOTHILLS AND PIEDMONT...INCLUDING PARTIAL THICKNESSES...SHOULD
SUPPORT SN ACROSS THE MTNS...RASN ACROSS THE FOOTHILLS...WITH RA
ACROSS THE PIEDMONT. HOWEVER...STRONGER SHOWERS SHOULD RESULT IN
PURE SN THIS MORNING...EVEN OVER THE PIEDMONT. BASED ON A BLEND OF
HPC...WRFARW...AND RUC QPF...I WILL FORECAST 2-3 INCHES ACROSS THE
TN BORDER CO...AND THE SOUTHERN AND CENTRAL MTNS...WITH 4 INCHES
POSSIBLE IN SPOTS ALONG THE RIDGELINE OF THE SMOKIES. EXTREME NE GA
MAY SEE 0.5 TO 1.4 INCHES...WITH ACROSS AN INCH ACROSS OCONEE AND
PICKENS MTNS. AREAS EAST...INCLUDING THE GSP AND CLT METRO AREAS MAY
SEE AROUND 0.1-0.2 INCHES. HIGH TEMPERATURES ARE FORECAST TO RANGE
FROM THE 30S ACROSS THE MTNS TO THE LOW TO MID 40S EAST.
LATE THIS AFTERNOON...SREF INDICATES THAT MUCAPE WILL LIKELY POOL TO
AT LEAST 50 J/KG ACROSS THE FOOTHILLS AND PIEDMONT. AS THE H5 TROF
AXIS PIVOTS EAST OF THE MTNS. WEAKLY CONVECTIVE SHOWERS ARE EXPECTED
TO DEVELOP ACROSS THE FOOTHILLS. CONVECTIVE ALLOWING GUIDANCE
INDICATES THAT THE SHOWERS MAINLY ORGANIZE INTO A LINE OR A CLUSTER.
I WILL TIME THE CONVECTION EAST ACROSS THE EASTERN HALF OF THE
FORECAST AREA THIS AFTERNOON...REACHING KGSP AT 19Z...AND CLT BY 22Z.
TONIGHT...NWFS WILL GRADUALLY FADE ALONG THE TN BORDER THIS
EVENING...ENDING DURING THE LATE NIGHT HOURS. WINDS WILL REMAIN FROM
THE NW...RANGING FROM 5 TO 10 KTS. CLOUD COVER WILL DECREASE THROUGH
THE NIGHT...ESPECIALLY EAST OF THE MTNS. LOW TEMPERATURES SHOULD
RANGE FROM THE L20S ACROSS THE MTNS TO THE MID TO U20S EAST.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM SATURDAY...ONE FINAL SHORTWAVE WILL DROP INTO THE EAST
COAST TROUGH AXIS ON SUNDAY BEFORE IT DEPARTS...BRINGING MAINLY
CHANNELED VORTICITY FROM THE WRN GREAT LAKES TO THE WRN CAROLINAS.
DEEP LAYER MOISTURE WILL BE ABSENT WITH THIS FEATURE...BUT LINGERING
LOW LEVEL NW UPSLOPE FLOW MOISTURE MAY PERMIT ISOLATED SNOW SHOWERS
TO LINGER ALONG THE TN BORDER INTO THE MORNING HOURS BEFORE DRYING
UP. CHILLY THICKNESSES...AND LINGERING PATCHY MID AND HIGH
CLOUDS...WILL KEEP TEMPERATURES SEVERAL CATEGORIES BELOW NORMAL.
A FLAT UPPER RIDGE WILL CROSS THE AREA MONDAY THROUGH MONDAY NIGHT.
PLENTY OF HIGH LEVEL CLOUDS SHOULD TOP THE RIDGE AXIS IN THE SWIFT
WESTERLY FLOW ALOFT DURING THIS PERIOD. THE AIRMASS SHOULD MODIFY
ENOUGH TO PUSH MAX TEMPERATURES BACK INTO THE 50S THROUGHOUT MON
AFTN...EXCEPT 40S ALONG THE HIGHER MOUNTAINS.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 310 AM SATURDAY...THERE IS GENERALLY GOOD CONSENSUS AMONG THE
VARIOUS MODELS ON A DEEPENING LOW PRES SYSTEM MOVING SE THROUGH THE
MIDWEST ON TUE...CROSSING THE FORECAST AREA ON WED...THEN DEEPENING
FURTHER ALONG THE IMMEDIATE E COAST WED NIGHT. HOWEVER...DIFFERENCES
AMONG THE MODELS IN THE SFC LOW AND 850 MB LOW CENTER TRACKS WILL
PLAY A CRITICAL ROLE IN PRECIPITATION TYPE AND AMOUNT. THERE IS GOOD
AGREEMENT THAT ISENTROPIC LIFT AHEAD OF THE SYSTEM WILL RETURN TO
THE REGION LATE MON NIGHT...WITH THE BEST BELT OF UPGLIDE ACROSS THE
HEART OF THE AREA MIDDAY TUE. PROFILES SUPPORT MAINLY RAIN ON THE
WARM ADVECTION SIDE OF THE SYSTEM...BUT WITH FREEZING RAIN POSSIBLE
IN SPOTS AT ONSET...ESPECIALLY ACROSS THE NRN NC MOUNTAINS.
THICKNESSES SHOULD CRASH WED MORNING AS THE COLD LOW PRESSURE SYSTEM
TRANSITIONS TOWARD THE COAST. QG FORCING SHOULD BE PLENTIFUL JUST
AHEAD OF THE LOW TUE NIGHT AND WED MORNING...WITH SOME DEGREE OF
FRONTOGENESIS AND DEFORMATION ZONE FORCING TRAILING THE DEPARTING
LOW THROUGH THE PIEDMONT WED AFTN/EVENING. VERY STEEP LAPSE RATES
UNDER THE PASSING UPPER LOW SHOULD SUPPORT AT LEAST ISOLD TO SCT
THUNDERSTORMS/THUNDERSNOW AT TIMES. CONFIDENCE IS HIGHEST ON
SIGNIFICANT ACCUMULATING SNOW OVER THE MTNS AND ALSO NC FOOTHILL AND
PIEDMONT LOCATIONS ALONG AND NORTH OF INTERSTATE 40. MORE OF A
RAIN/SNOW MIX IS EXPECTED TOWARD THE INTERSTATE 85 CORRIDOR AND
POINTS SOUTH...BUT LIKELY ENDING AS SNOW SHOWERS. WILL CONTINUE THE
HWO MENTION FOR THIS POTENTIALLY SIGNIFICANT WINTER STORM SYSTEM.
A WARMER AND DRY RIDGE PATTERN WILL RETURN THU THROUGH FRI...WITH
TEMPERATURES SLOWLY REBOUNDING TO WITHIN 5 DEGREES OF NORMAL.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...THE 12Z TAF WILL BEGIN WITH VFR CONDITIONS AND A LIGHT NE
WIND. CEILING BASES SHOULD GRADUALLY LOWER THROUGH MID MORNING AS
SYNOPTIC SCALE FORCING SPREADS ACROSS THE PIEDMONT. BETWEEN 12Z TO
18Z...MID LEVEL FORCING SHOULD PEAK ACROSS THE TERMINAL...THEN
WEAKEN THROUGH THE AFTERNOON HOURS. NAM FORECAST SOUNDINGS SUPPORTS
CEILINGS FALLING TO LVFR BETWEEN 12Z TO 15Z. THE ARRIVAL OF THE DEEP
FORCING AT DAY BREAK MAY YIELD ONE OF THE HIGHEST CHCS FOR PRECIP
DURING THE PERIOD. ANOTHER BAND OF RASN MAY PASS ACROSS THE TERMINAL
BETWEEN 22Z TO 24Z WITH THE PUSH OF THE DRY SLOT. ONCE THE DRY SLOT
ARRIVES...CEILINGS WILL LIFT AND STEADY NW WINDS SHOULD REMAIN
THROUGH 12Z SUN. I WOULD EXPECT THAT ACCUMULATING SNOW IS POSSIBLE
THIS MORNING AND AGAIN LATE THIS AFTERNOON...ACCUMS WILL LIKELY
REMAIN LESS THAN A HALF INCH.
ELSEWHERE...TIMING SIMILAR TO CLT. HOWEVER...KGSP...KGMU...AND KHKY
SHOULD SEE WINDOWS OF MVFR CEILINGS DEVELOP BETWEEN 12 TO 15Z...BUT
DOWNSLOPE FLOW SHOULD SUPPORT VFR BY MID MORNING. ALL AREAS WILL SEE
THE POTENTIAL FOR LIGHT ACCUMULATING SNOW THIS MORNING....BEST CHC
BETWEEN 12Z TO 16Z. HOWEVER...THE FORMATION OF A WEAKLY CONVECTIVE
BAND THIS AFTERNOON WILL NEED CLOSE ATTENTION.
OUTLOOK...SNOW SHOWERS WILL DIMINSIHING THE TENNESSEE BORDER ON
SUNDAY. MONDAY SHOULD REMAIN VFR ACROSS THE FORECAST AREA.
ANOTHER LOW PRESSURE SYSTEM WILL SPREAD LLVL MOISTURE AND
PRECIPITATION ACROSS THE REGION TUESDAY AND WEDNESDAY MORNING.
CONFIDENCE TABLE...
12-18Z 18-24Z 00-06Z 06-12Z
KCLT HIGH 87% HIGH 90% HIGH 100% HIGH 100%
KGSP HIGH 89% HIGH 100% HIGH 100% HIGH 100%
KAVL MED 75% HIGH 98% HIGH 100% HIGH 100%
KHKY HIGH 83% HIGH 99% HIGH 100% HIGH 100%
KGMU HIGH 87% HIGH 98% HIGH 100% HIGH 100%
KAND HIGH 88% HIGH 99% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR GAZ010-
017-018-026.
NC...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ033-
048>052-058-059-062>064.
SC...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR SCZ001-
002-004.
&&
$$
SYNOPSIS...HG
NEAR TERM...NED
SHORT TERM...HG
LONG TERM...HG
AVIATION...NED
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
505 AM CST SAT MAR 2 2013
.DISCUSSION.../ISSUED AT 400 AM CST/
NEAR TERM CHALLENGE IS THE LAST REMNANTS OF SOME STRATUS NOSING UP
INTO PARTS OF NORTHWEST IA...ALONG AND JUST EAST OF THE BIG SIOUX
RIVER AT THIS TIME. SITUATED NEAR 925MB...IT IS SLOWLY EDGING
SOUTHWARD AND SHOULD CONTINUE TO PROCEED IN THAT DIRECTION THROUGH
15Z THIS MORNING. AT THAT TIME...BOTH THE NAM12 AND RAP ARE IN GOOD
AGREEMENT IN SHIFTING THE 925MB WINDS FROM THE NORTH/NORTHWEST TO
THE SOUTH BETWEEN 15Z AND 18Z. THEREFORE IF ANY STRATUS IS STILL IN
OUR FAR SOUTHEAST ZONES AT 15Z...IT MAY HAVE TROUBLE LEAVING THAT
AREA UNLESS IT MIXES OUT SOME. OTHERWISE...MID AND HIGH LEVEL CLOUDS
WILL INCREASE TODAY GIVING A PARTLY SUNNY TO MOSTLY CLOUDY SKY
OVERALL. SURFACE RIDGING IS MOVING EASTWARD AT THIS TIME ACROSS OUR
FORECAST AREA WHICH WILL SHIFT THE SURFACE WINDS TO THE SOUTH. GIVEN
THE NAM AND GFS 925MB TEMPERATURES...ANOTHER SEASONALLY COOL DAY
WILL BE IN STORE FOR AREAS ALONG AND EAST OF I 29. HOWEVER OUR
CENTRAL SD ZONES SHOULD WARM INTO THE LOWER AND MID 40S.
NO CHANGES REALLY NEEDED FOR THE TONIGHT PERIOD...WITH A SOUTHEAST
BREEZE STAYING BRISK. THEREFORE NOT ANTICIPATING TEMPERATURES
FALLING OFF ALL THAT MUCH. DUE TO THE BREEZE...WE MAY BE A BIT TOO
COOL WITH THE LOWS TONIGHT SO THAT IS SOMETHING TO WATCH FOR.
ON SUNDAY...WELL ADVERTISED UPPER WAVE BEGINS TO MOVE INTO THE IDAHO
AND WESTERN MT REGION. AHEAD OF IT...SURFACE LOW PRESSURE FORMS IN A
NORTH TO SOUTH ELONGATION ALONG THE FRONT RANGE OF THE ROCKIES. THE
NORTHERN PORTION OF THE LOW THEN EXTENDS A DECENT WARM FRONT
SOUTHEASTWARD INTO THE CENTRAL PLAINS. TO THE NORTH OF THE WARM
FRONT...INDICATIONS ARE INCREASING THAT THERE MAY BE ENOUGH
SATURATION AND ISENTROPIC LIFT TO PRODUCE SOME LIGHT
PRECIPITATION...WITH THE TYPE DEPENDING ON SURFACE TO 850MB
TEMPERATURES. THE MOST CONCERN AT THIS TIME IS IN AN AREA FROM
EASTERN KINGSBURY AND WESTERN BROOKINGS COUNTIES...WHERE THERE COULD
BE SOME LIGHT FREEZING RAIN. RIGHT NOW...HAVE VERY MINIMAL
ACCUMULATIONS OF ICE IN THOSE AREAS BECAUSE SURFACE TEMPERATURES
SHOULD WARM INTO THE LOWER 30S DURING THE AFTERNOON. BUT WILL LIKELY
MENTION THIS POSSIBILITY IN THE FORTH COMING HWO. CLOSER TO THE WARM
FRONT...TEMPERATURES WILL BE QUITE MILD IN OUR CENTRAL SD ZONES...
WITH 40S WIDESPREAD IN THOSE AREAS. CONVERSELY IN OUR NORTHEAST
ZONES...LOWER 30S IS LIKELY ALL THE WARMING THEY WILL GET.
FOR THE REST OF THE FORECAST SUNDAY NIGHT THROUGH MONDAY NIGHT...
FOLLOWED A BLEND OF THE 00Z GFS/00Z GEM GLOBAL AND 12Z ECMWF. THE
NAM LOOKS TO BE A NORTHERN OUTLIER AT THIS TIME AS IT SO OFTEN IS
WITH SYSTEMS IN THE NORTHERN JET STREAM MOVING OUT OF THE NORTHERN
ROCKIES. THAT SAID...THE 00Z ECMWF DID ALSO TREND A BIT FURTHER
NORTHWARD WITH THE STORM TRACK COMPARED WITH ITS 12Z COUNTERPART.
HAVE NOTICED THE LAST COUPLE OF DAYS THAT THE ECMWF IS BATTLING
ITSELF WITH THE 00Z RUNS FURTHER NORTH THEN THE 12Z RUNS WHICH IS
INTERESTING.
ON SUNDAY NIGHT...MOST OF THE PRECIPITATION WILL STILL LIKELY LIE
NEAR THE 850MB BAROCLINIC ZONE CLOSE TO THE AFOREMENTIONED WARM
FRONT. BROAD LIFT IS PRETTY STRONG IN OUR NORTHERN AND EASTERN ZONES
ALL NIGHT. AND WITH TEMPERATURES COOLING ALOFT TO SUB ZERO...AGAIN
USING THE ABOVE MENTIONED MODEL BLEND...SNOW WILL BE LIKELY FOR
AREAS NORTH OF OUR MISSOURI RIVER VALLEY COUNTIES. AT THIS TIME...
IT APPEARS UPWARDS OF 3 TO 3.5 INCHES COULD FALL IN AN AXIS FROM
FROM AROUND BROOKINGS...TO WORTHINGTON...TO SPENCER IOWA. LIGHTER
AMOUNTS WILL THEN FOLLOW SUIT ON BOTH SIDES OF THAT AXIS BUT ANY
DEVIATION IN THE STORM TRACK COULD REALLY FOUL UP THIS THINKING. LOW
TEMPERATURES WILL AGAIN NOT LIKELY FALL TOO MUCH FROM DAYTIME
HIGHS...WITH A LOT OF 20S ANTICIPATED. BECAUSE OF TEMPERATURES BELOW
FREEZING COUPLED WITH WARM TEMPERATURES ALOFT...EVEN ON THE SOUTHERN
TRACK SOLUTIONS...AM A BIT CONCERNED ABOUT MORE LIGHT FREEZING RAIN
POTENTIAL LATE SUNDAY NIGHT IN AN AREA FROM CHAMBERLAIN TO LAKE
ANDES.
THEN ON MONDAY AND MONDAY NIGHT...THE AFOREMENTIONED MODEL BLEND
DIVES THE UPPER LOW SOUTHEASTWARD TOWARD TOPEKA KS/KANSAS CITY AREA
BY 12Z TUESDAY. THIS TRACK WOULD BE FAVORABLE FOR GIVING THE
NORTHEAST HALF OF OUR FORECAST AREA ACCUMULATING SNOW EITHER IN THE
ADVISORY OR WARNING CRITERIA CATEGORIES. GFS UPPER QG FORCING IS
MAXIMIZED IN A TRACK JUST SOUTH OF OUR MISSOURI RIVER VALLEY ZONES
WITH STRONG PV FORCING FOLLOWING SUIT. NOW ONE THING TO MENTION...IS
IT IS DIFFICULT TO TELL AT THIS POINT WHERE ANY MESOSCALE TO
MICROSCALE FRONTAL BANDING WILL TAKE PLACE OR ANY POTENTIAL UPPER
INSTABILITY. THE GLOBAL TYPE MODELS HAVE A TENDENCY TO WASH OUT
THESE FEATURES OUT AND THE ONE MODEL THAT COULD SHOW THIS...
THE NAM...WAS NOT USED. SO HEAVIER AMOUNTS OF SNOW IN FRONTAL
INSTABILITY BANDS COULD OCCUR...AND IF THEY DO...RIGHT NOW THE MOST
LIKELY PLACE WOULD PROBABLY BE ALONG AND EAST OF A BROOKINGS SD TO
SPENCER IA LINE. THEREFORE PUT THESE AREAS IN A WINTER STORM WATCH.
AND EVEN WITHOUT THE FRONTAL BANDING...THESE AREAS ADD UP TO AROUND
8 INCHES OF STORM TOTAL SNOW IN A 24 TO 36 HOUR PERIOD. IT REALLY
NEEDS TO BE STRESSED HOWEVER THAT ANY STORM TRACK DEVIATION COULD
HAVE HUGE CONSEQUENCES ON SNOW AMOUNTS. THERE WILL LIKELY BE AN
EXTREMELY SHARP CUTOFF OF PRECIPITATION ON THE SOUTHERN END OF THE
SNOW SHIELD. AND IF THE NAM TURNS OUT TO BE MORE CORRECT IN
PLACEMENT AND KEEPING THINGS FURTHER NORTH...OUR FORECAST AREA WILL
BE MUCH MORE DRY SLOTTED. CONVERSELY...IF THE TRACK HEDGES SOUTH...
THEN WE WILL NEED TO PUT HEAVIER SNOW TOTALS AND HEADLINES TO THE
WEST OF OUR CURRENT WATCH. SO ADJUSTMENTS IN FUTURE FORECASTS WILL
BE LIKELY. /MJF
IN THE EXTENDED PERIOD...TUESDAY THROUGH FRIDAY...THE SYSTEM BEGINS
TO PULL AWAY FROM THE AREA WITH LINGERING LIGHT SNOW...MAINLY IN OUR
EAST...DIMINISHING THROUGH THE DAY. THERMAL PROFILES CONTINUE TO
COOL ON TUESDAY...AND WITH CLOUD COVER AND LIKELY SNOW COVER STAYED
ON THE COOLER SIDE OF GUIDANCE WITH HIGHS IN THE UPPER 20S ALONG THE
MISSOURI RIVER CORRIDOR TO THE LOWER 20S NORTHEAST. A SURFACE RIDGE
AXIS BUILDS SOUTHWARD INTO OUR AREA DURING THE DAY...BECOMING
SITUATED DIRECTLY OVERHEAD ON TUESDAY NIGHT. WITH CLEARING
SKIES...DYING WINDS...AND FRESH SNOW COVER...WENT BELOW ALL BLEND
GUIDANCE...AND IT MAY ACTUALLY BE EVEN COLDER IF THINGS SET UP
RIGHT. AT THIS POINT HAVE LOWS IN THE LOWER SINGLE DIGITS NORTHEAST
TO THE LOWER AND MID TEENS IN THE FAR WEST.
UPPER LEVEL RIDGING BEGINS TO BUILD INTO THE REGION ON
WEDNESDAY...AS THE SURFACE HIGH PRESSURE PUSHES OFF TO THE EAST WITH
A SOUTHERLY LOW LEVEL FLOW DEVELOPING ON THE BACKSIDE OF THE HIGH.
AS A RESULT...TEMPERATURES WILL ATTEMPT TO WARM ACROSS THE
AREA...THOUGH STUNTED BY SNOW COVER. THE BEST WARMING POTENTIAL
LOOKS TO BE IN OUR SOUTHWEST WITH HIGHS INTO THE UPPER
30S...TAPERING DOWN TO THE EAST WITH READINGS ONLY IN THE MID 20S
NORTH AND EAST OF A GENERAL BROOKINGS TO SPENCER LINE. WINDS WILL
BEGIN TO PICK UP ON WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT AS THE
GRADIENT TIGHTENS IN RESPONSE TO A DEVELOPING LOW PRESSURE TROUGH
OVER THE EASTERN ROCKIES/WESTERN HIGH PLAINS. AS A RESULT...IT WILL
BE A MUCH MILDER NIGHT ON WEDNESDAY NIGHT WITH LOWS UPPER 20S WEST
TO MID/UPPER TEENS EAST.
THURSDAY WILL BE THE WARM DAY OF THE WEEK IN A STRONG SOUTHERLY FLOW
OUT AHEAD OF THE AFOREMENTIONED SURFACE TROUGH. AGAIN...DEEPER SNOW
COVER IN SOME AREAS WILL TEMPER HIGHS SOMEWHAT...THOUGH PORTIONS OF
OUR SOUTH CENTRAL SOUTH DAKOTA ZONES MAY MAKE IT UP INTO THE UPPER
40S WHERE PROGGED 925 MB TEMPS WILL REACH JUST EITHER SIDE OF 10C ON
THURSDAY AFTERNOON. BACK TO THE NORTH AND EAST...WHERE THERE IS THE
POTENTIAL FOR DEEPER SNOW COVER...HIGHS WILL MOST LIKELY BE STUCK IN
THE 30S.
ON FRIDAY...THE GFS AND ECMWF IN DECENT AGREEMENT ON BRINGING UPPER
LEVEL ENERGY ACROSS NORTH DAKOTA...PROBABLY KEEPING ANY
PRECIPITATION POTENTIAL TO THE NORTH OF US...THOUGH PULLING A COLD
FRONT THROUGH OUR AREA LATE THURSDAY NIGHT INTO FRIDAY. LOOKS TO BE
A DRY FRONTAL PASSAGE FOR THE MOST PART WITH LIMITED MOISTURE WITH
THE SYSTEM...THOUGH WILL RESULT IN A COOL DOWN FOR FRIDAY.
&&
.AVIATION.../FOR THE 12Z TAF ISSUANCE/
LINGERING STRATUS JUST TO THE EAST OF KSUX VERY EARLY THIS MORNING
WILL CONTINUE TO PUSH OFF TO THE SOUTHEAST THROUGH THE MORNING WITH
925 MB WINDS OUT OF THE NORTHWEST OVER THAT AREA.
OTHERWISE...POCKETS OF STRATUS OVER THE AREA WILL DISSIPATE THROUGH
THE MORNING WITH SCATTERED MID AND HIGH CLOUDS REMAINING THROUGH THE
DAY. GUIDANCE POINTING TOWARD STRATUS RETURNING TO THE AREA BY LATE
THIS AFTERNOON OR EVENING.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WINTER STORM WATCH FROM SUNDAY EVENING THROUGH LATE MONDAY NIGHT
FOR SDZ040.
MN...WINTER STORM WATCH FROM SUNDAY EVENING THROUGH LATE MONDAY NIGHT
FOR MNZ071-072-080-081-089-090-097.
IA...WINTER STORM WATCH FROM SUNDAY EVENING THROUGH LATE MONDAY NIGHT
FOR IAZ002-003-014.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
400 AM CST SAT MAR 2 2013
.DISCUSSION.../ISSUED AT 400 AM CST/
NEAR TERM CHALLENGE IS THE LAST REMNANTS OF SOME STRATUS NOSING UP
INTO PARTS OF NORTHWEST IA...ALONG AND JUST EAST OF THE BIG SIOUX
RIVER AT THIS TIME. SITUATED NEAR 925MB...IT IS SLOWLY EDGING
SOUTHWARD AND SHOULD CONTINUE TO PROCEED IN THAT DIRECTION THROUGH
15Z THIS MORNING. AT THAT TIME...BOTH THE NAM12 AND RAP ARE IN GOOD
AGREEMENT IN SHIFTING THE 925MB WINDS FROM THE NORTH/NORTHWEST TO
THE SOUTH BETWEEN 15Z AND 18Z. THEREFORE IF ANY STRATUS IS STILL IN
OUR FAR SOUTHEAST ZONES AT 15Z...IT MAY HAVE TROUBLE LEAVING THAT
AREA UNLESS IT MIXES OUT SOME. OTHERWISE...MID AND HIGH LEVEL CLOUDS
WILL INCREASE TODAY GIVING A PARTLY SUNNY TO MOSTLY CLOUDY SKY
OVERALL. SURFACE RIDGING IS MOVING EASTWARD AT THIS TIME ACROSS OUR
FORECAST AREA WHICH WILL SHIFT THE SURFACE WINDS TO THE SOUTH. GIVEN
THE NAM AND GFS 925MB TEMPERATURES...ANOTHER SEASONALLY COOL DAY
WILL BE IN STORE FOR AREAS ALONG AND EAST OF I 29. HOWEVER OUR
CENTRAL SD ZONES SHOULD WARM INTO THE LOWER AND MID 40S.
NO CHANGES REALLY NEEDED FOR THE TONIGHT PERIOD...WITH A SOUTHEAST
BREEZE STAYING BRISK. THEREFORE NOT ANTICIPATING TEMPERATURES
FALLING OFF ALL THAT MUCH. DUE TO THE BREEZE...WE MAY BE A BIT TOO
COOL WITH THE LOWS TONIGHT SO THAT IS SOMETHING TO WATCH FOR.
ON SUNDAY...WELL ADVERTISED UPPER WAVE BEGINS TO MOVE INTO THE IDAHO
AND WESTERN MT REGION. AHEAD OF IT...SURFACE LOW PRESSURE FORMS IN A
NORTH TO SOUTH ELONGATION ALONG THE FRONT RANGE OF THE ROCKIES. THE
NORTHERN PORTION OF THE LOW THEN EXTENDS A DECENT WARM FRONT
SOUTHEASTWARD INTO THE CENTRAL PLAINS. TO THE NORTH OF THE WARM
FRONT...INDICATIONS ARE INCREASING THAT THERE MAY BE ENOUGH
SATURATION AND ISENTROPIC LIFT TO PRODUCE SOME LIGHT
PRECIPITATION...WITH THE TYPE DEPENDING ON SURFACE TO 850MB
TEMPERATURES. THE MOST CONCERN AT THIS TIME IS IN AN AREA FROM
EASTERN KINGSBURY AND WESTERN BROOKINGS COUNTIES...WHERE THERE COULD
BE SOME LIGHT FREEZING RAIN. RIGHT NOW...HAVE VERY MINIMAL
ACCUMULATIONS OF ICE IN THOSE AREAS BECAUSE SURFACE TEMPERATURES
SHOULD WARM INTO THE LOWER 30S DURING THE AFTERNOON. BUT WILL LIKELY
MENTION THIS POSSIBILITY IN THE FORTH COMING HWO. CLOSER TO THE WARM
FRONT...TEMPERATURES WILL BE QUITE MILD IN OUR CENTRAL SD ZONES...
WITH 40S WIDESPREAD IN THOSE AREAS. CONVERSELY IN OUR NORTHEAST
ZONES...LOWER 30S IS LIKELY ALL THE WARMING THEY WILL GET.
FOR THE REST OF THE FORECAST SUNDAY NIGHT THROUGH MONDAY NIGHT...
FOLLOWED A BLEND OF THE 00Z GFS/00Z GEM GLOBAL AND 12Z ECMWF. THE
NAM LOOKS TO BE A NORTHERN OUTLIER AT THIS TIME AS IT SO OFTEN IS
WITH SYSTEMS IN THE NORTHERN JET STREAM MOVING OUT OF THE NORTHERN
ROCKIES. THAT SAID...THE 00Z ECMWF DID ALSO TREND A BIT FURTHER
NORTHWARD WITH THE STORM TRACK COMPARED WITH ITS 12Z COUNTERPART.
HAVE NOTICED THE LAST COUPLE OF DAYS THAT THE ECMWF IS BATTLING
ITSELF WITH THE 00Z RUNS FURTHER NORTH THEN THE 12Z RUNS WHICH IS
INTERESTING.
ON SUNDAY NIGHT...MOST OF THE PRECIPITATION WILL STILL LIKELY LIE
NEAR THE 850MB BAROCLINIC ZONE CLOSE TO THE AFOREMENTIONED WARM
FRONT. BROAD LIFT IS PRETTY STRONG IN OUR NORTHERN AND EASTERN ZONES
ALL NIGHT. AND WITH TEMPERATURES COOLING ALOFT TO SUB ZERO...AGAIN
USING THE ABOVE MENTIONED MODEL BLEND...SNOW WILL BE LIKELY FOR
AREAS NORTH OF OUR MISSOURI RIVER VALLEY COUNTIES. AT THIS TIME...
IT APPEARS UPWARDS OF 3 TO 3.5 INCHES COULD FALL IN AN AXIS FROM
FROM AROUND BROOKINGS...TO WORTHINGTON...TO SPENCER IOWA. LIGHTER
AMOUNTS WILL THEN FOLLOW SUIT ON BOTH SIDES OF THAT AXIS BUT ANY
DEVIATION IN THE STORM TRACK COULD REALLY FOUL UP THIS THINKING. LOW
TEMPERATURES WILL AGAIN NOT LIKELY FALL TOO MUCH FROM DAYTIME
HIGHS...WITH A LOT OF 20S ANTICIPATED. BECAUSE OF TEMPERATURES BELOW
FREEZING COUPLED WITH WARM TEMPERATURES ALOFT...EVEN ON THE SOUTHERN
TRACK SOLUTIONS...AM A BIT CONCERNED ABOUT MORE LIGHT FREEZING RAIN
POTENTIAL LATE SUNDAY NIGHT IN AN AREA FROM CHAMBERLAIN TO LAKE
ANDES.
THEN ON MONDAY AND MONDAY NIGHT...THE AFOREMENTIONED MODEL BLEND
DIVES THE UPPER LOW SOUTHEASTWARD TOWARD TOPEKA KS/KANSAS CITY AREA
BY 12Z TUESDAY. THIS TRACK WOULD BE FAVORABLE FOR GIVING THE
NORTHEAST HALF OF OUR FORECAST AREA ACCUMULATING SNOW EITHER IN THE
ADVISORY OR WARNING CRITERIA CATEGORIES. GFS UPPER QG FORCING IS
MAXIMIZED IN A TRACK JUST SOUTH OF OUR MISSOURI RIVER VALLEY ZONES
WITH STRONG PV FORCING FOLLOWING SUIT. NOW ONE THING TO MENTION...IS
IT IS DIFFICULT TO TELL AT THIS POINT WHERE ANY MESOSCALE TO
MICROSCALE FRONTAL BANDING WILL TAKE PLACE OR ANY POTENTIAL UPPER
INSTABILITY. THE GLOBAL TYPE MODELS HAVE A TENDENCY TO WASH OUT
THESE FEATURES OUT AND THE ONE MODEL THAT COULD SHOW THIS...
THE NAM...WAS NOT USED. SO HEAVIER AMOUNTS OF SNOW IN FRONTAL
INSTABILITY BANDS COULD OCCUR...AND IF THEY DO...RIGHT NOW THE MOST
LIKELY PLACE WOULD PROBABLY BE ALONG AND EAST OF A BROOKINGS SD TO
SPENCER IA LINE. THEREFORE PUT THESE AREAS IN A WINTER STORM WATCH.
AND EVEN WITHOUT THE FRONTAL BANDING...THESE AREAS ADD UP TO AROUND
8 INCHES OF STORM TOTAL SNOW IN A 24 TO 36 HOUR PERIOD. IT REALLY
NEEDS TO BE STRESSED HOWEVER THAT ANY STORM TRACK DEVIATION COULD
HAVE HUGE CONSEQUENCES ON SNOW AMOUNTS. THERE WILL LIKELY BE AN
EXTREMELY SHARP CUTOFF OF PRECIPITATION ON THE SOUTHERN END OF THE
SNOW SHIELD. AND IF THE NAM TURNS OUT TO BE MORE CORRECT IN
PLACEMENT AND KEEPING THINGS FURTHER NORTH...OUR FORECAST AREA WILL
BE MUCH MORE DRY SLOTTED. CONVERSELY...IF THE TRACK HEDGES SOUTH...
THEN WE WILL NEED TO PUT HEAVIER SNOW TOTALS AND HEADLINES TO THE
WEST OF OUR CURRENT WATCH. SO ADJUSTMENTS IN FUTURE FORECASTS WILL
BE LIKELY. /MJF
IN THE EXTENDED PERIOD...TUESDAY THROUGH FRIDAY...THE SYSTEM BEGINS
TO PULL AWAY FROM THE AREA WITH LINGERING LIGHT SNOW...MAINLY IN OUR
EAST...DIMINISHING THROUGH THE DAY. THERMAL PROFILES CONTINUE TO
COOL ON TUESDAY...AND WITH CLOUD COVER AND LIKELY SNOW COVER STAYED
ON THE COOLER SIDE OF GUIDANCE WITH HIGHS IN THE UPPER 20S ALONG THE
MISSOURI RIVER CORRIDOR TO THE LOWER 20S NORTHEAST. A SURFACE RIDGE
AXIS BUILDS SOUTHWARD INTO OUR AREA DURING THE DAY...BECOMING
SITUATED DIRECTLY OVERHEAD ON TUESDAY NIGHT. WITH CLEARING
SKIES...DYING WINDS...AND FRESH SNOW COVER...WENT BELOW ALL BLEND
GUIDANCE...AND IT MAY ACTUALLY BE EVEN COLDER IF THINGS SET UP
RIGHT. AT THIS POINT HAVE LOWS IN THE LOWER SINGLE DIGITS NORTHEAST
TO THE LOWER AND MID TEENS IN THE FAR WEST.
UPPER LEVEL RIDGING BEGINS TO BUILD INTO THE REGION ON
WEDNESDAY...AS THE SURFACE HIGH PRESSURE PUSHES OFF TO THE EAST WITH
A SOUTHERLY LOW LEVEL FLOW DEVELOPING ON THE BACKSIDE OF THE HIGH.
AS A RESULT...TEMPERATURES WILL ATTEMPT TO WARM ACROSS THE
AREA...THOUGH STUNTED BY SNOW COVER. THE BEST WARMING POTENTIAL
LOOKS TO BE IN OUR SOUTHWEST WITH HIGHS INTO THE UPPER
30S...TAPERING DOWN TO THE EAST WITH READINGS ONLY IN THE MID 20S
NORTH AND EAST OF A GENERAL BROOKINGS TO SPENCER LINE. WINDS WILL
BEGIN TO PICK UP ON WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT AS THE
GRADIENT TIGHTENS IN RESPONSE TO A DEVELOPING LOW PRESSURE TROUGH
OVER THE EASTERN ROCKIES/WESTERN HIGH PLAINS. AS A RESULT...IT WILL
BE A MUCH MILDER NIGHT ON WEDNESDAY NIGHT WITH LOWS UPPER 20S WEST
TO MID/UPPER TEENS EAST.
THURSDAY WILL BE THE WARM DAY OF THE WEEK IN A STRONG SOUTHERLY FLOW
OUT AHEAD OF THE AFOREMENTIONED SURFACE TROUGH. AGAIN...DEEPER SNOW
COVER IN SOME AREAS WILL TEMPER HIGHS SOMEWHAT...THOUGH PORTIONS OF
OUR SOUTH CENTRAL SOUTH DAKOTA ZONES MAY MAKE IT UP INTO THE UPPER
40S WHERE PROGGED 925 MB TEMPS WILL REACH JUST EITHER SIDE OF 10C ON
THURSDAY AFTERNOON. BACK TO THE NORTH AND EAST...WHERE THERE IS THE
POTENTIAL FOR DEEPER SNOW COVER...HIGHS WILL MOST LIKELY BE STUCK IN
THE 30S.
ON FRIDAY...THE GFS AND ECMWF IN DECENT AGREEMENT ON BRINGING UPPER
LEVEL ENERGY ACROSS NORTH DAKOTA...PROBABLY KEEPING ANY
PRECIPITATION POTENTIAL TO THE NORTH OF US...THOUGH PULLING A COLD
FRONT THROUGH OUR AREA LATE THURSDAY NIGHT INTO FRIDAY. LOOKS TO BE
A DRY FRONTAL PASSAGE FOR THE MOST PART WITH LIMITED MOISTURE WITH
THE SYSTEM...THOUGH WILL RESULT IN A COOL DOWN FOR FRIDAY.
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
MVFR STRATUS WILL SLOWLY ERODE ACROSS NORTHWEST IOWA. SOME SHORT
LIVED FOG DEVELOPED IN THE JAMES VALLEY...BUT WILL SEE INCREASE IN
EASTERLY WINDS AND INCREASE IN CIRRUS SHOULD LIMIT FURTHER
DEVELOPMENT. NEAR LOW LEVEL RIDGE AXIS AS IT SHIFTS CLOSER TO THE
I29 CORRIDOR LIKELY THAT AREAS OF MVFR FOG WILL DEVELOP IN THE
08Z-15Z TIMEFRAME...BUT COVERAGE WILL BE SOMEWHAT DEPENDENT ON
THICKNESS OF APPROACHING CIRRUS SHIELD AND HOW QUICKLY THE
SOUTHEASTERLY GRADIENT INCREASES. INCREASE IN VFR CEILING COVERAGE
WILL OCCUR ON SATURDAY. HOWEVER...LOWER MVFR CEILINGS EXPECTED TO
DEVELOP IN STABLY STRATIFIED AIRMASS ACROSS THE ENTIRE AREA DURING
THE EVENING ON SATURDAY. /CHAPMAN
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WINTER STORM WATCH FROM SUNDAY EVENING THROUGH LATE MONDAY NIGHT
FOR SDZ040.
MN...WINTER STORM WATCH FROM SUNDAY EVENING THROUGH LATE MONDAY NIGHT
FOR MNZ071-072-080-081-089-090-097.
IA...WINTER STORM WATCH FROM SUNDAY EVENING THROUGH LATE MONDAY NIGHT
FOR IAZ002-003-014.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
518 AM CST SAT MAR 2 2013
.SHORT TERM...TODAY THROUGH TUESDAY
332 AM CST SAT MAR 2 2013
UPDATED LAST PARAGRAPH ABOUT THE ACCUMULATING SNOW POTENTIAL FOR
SUNDAY NIGHT THROUGH TUESDAY...MENTIONING THAT WINTER STORM WATCHES
MAY BE REQUIRED.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED RIDGING AGAIN OVER THE WESTERN U.S. AND BEGINNING TO ENTER
THE WESTERN PORTION OF THE PLAINS...WHILE TROUGHING STILL
DOMINATED THE EASTERN U.S. A SHORTWAVE TROUGH WAS EVIDENT OVER THE
FORECAST AREA...PRODUCING SOME CIRRUS AHEAD OF IT OVER EASTERN
WISCONSIN. OTHERWISE...THE AIRMASS HAS DRIED OUT QUITE A
BIT...NOTED BY THE 00Z MPX SOUNDING WITH A PRECIPITABLE WATER OF
0.17 INCHES OR 71 PERCENT OF NORMAL. A LIGHT NORTHERLY BREEZE
CONTINUES AHEAD OF A HIGH PRESSURE RIDGE IN FAR WESTERN MINNESOTA.
THIS BREEZE HAS SO FAR KEPT TEMPERATURES FROM COMPLETELY
PLUMMETING. FARTHER WEST...MID AND HIGH CLOUDS WERE INCREASING
ACROSS THE DAKOTAS AHEAD OF THE BUILDING UPPER RIDGE...IN A
GENERAL WARM ADVECTION PATTERN. NO EVIDENCE YET OF PRECIPITATION
FALLING OUT OF THEM...LIKELY DUE TO THE DRY AIR BETWEEN 600-800MB
ON THE 00Z BIS SOUNDING. AIRMASS AROUND THE NORTHERN PLAINS HAS
WARMED UP SOMEWHAT WITH 850MB TEMPS FROM ABR TO MPX AND GRB AROUND
-8C PER 00Z SOUNDINGS. THE MPX AND GRB OBSERVATIONS WERE ABOUT 2C
WARMER THAN WHAT 01.00Z MODELS FORECASTED. WELL OFF TO THE
WEST...A POTENT UPPER TROUGH WAS LOCATED OVER THE EAST PACIFIC
NEAR 45 N 139 W...WHICH WE ARE WATCHING FOR EARLY NEXT WEEK.
SHORT TERM HIGHLIGHTS / CONCERNS...
1. POTENTIAL FOR SOME LIGHT SNOW LATE TONIGHT/SUNDAY MORNING...
THE AREA OF THICKENING MID/HIGH CLOUDS ACROSS THE DAKOTAS WILL
EVENTUALLY SHIFT OVER THE FORECAST AREA TONIGHT AS THE WESTERN U.S.
RIDGE GETS PUSHED EASTWARD. ACCOMPANYING THE MID/HIGH CLOUDS IS SOME
LOW TO MID LEVEL FRONTOGENESIS AND WEAK ISENTROPIC LIFT ON THE
280-285K SURFACES. THE MAIN QUESTION IS IF ANY SNOW THAT IS PRODUCED
OUT OF THESE CLOUDS AND LIFT CAN MAKE IT TO THE SURFACE. THE 02.00Z
GFS/NAM/ECMWF/CANADIAN ARE ALL DRY...SUGGESTING THAT THE LOW LEVEL
DRY AIR LEFT BEHIND BY THE SURFACE RIDGE CROSSING THE FORECAST AREA
WILL BE ENOUGH TO ABSORB THE SNOW. ONLY THE 01.21Z SREF YIELDS A
SMALL POSSIBILITY OF SNOW ACROSS MUCH OF EASTERN MINNESOTA SUNDAY
MORNING. WILL LEAN TOWARDS THE MAJORITY IDEA AND KEEP A DRY FORECAST
GOING.
2. ACCUMULATING SNOW POTENTIAL SUNDAY NIGHT THROUGH TUESDAY...
GOOD MODEL AGREEMENT EXISTS THAT A FRONTOGENETIC BAND OF
PRECIPITATION WILL FORM FROM THE DAKOTAS SOUTHEAST INTO NORTHWEST
IOWA BY LATE SUNDAY. THIS BAND FORMS BECAUSE OF INTENSIFYING WARM
ADVECTION COMBINING WITH PACIFIC MOISTURE...DOWNSTREAM OF THE POTENT
TROUGH CURRENTLY IN THE EAST PACIFIC MOVING INTO MONTANA.
WHERE THE FRONTOGENETIC BAND GOES FROM HERE IN TIME HAS BEEN
PROBLEMATIC THE LAST COUPLE DAYS...AND THERE REMAINS PROBLEMS TODAY.
PART OF THE ISSUE IS SOLELY JUST ON THE POTENT TROUGH TRACK AND
SPEED. THE SPREAD AT 00Z TUESDAY RANGES FROM THE EASTERN DAKOTAS IN
THE 02.00Z NAM...CENTRAL DAKOTAS IN THE 02.00Z UKMET/ECMWF...AND THE
WESTERN DAKOTAS IN THE 02.00Z CANADIAN/GFS. IT IS WORTH NOTING THAT
THE LOCATION FROM ALL MODELS IS DEFINITELY WEST AND SLOWER THAN
THOSE SEEN FROM THE 01.00Z CYCLE. THE FASTER NAM WOULD BRING THE
FRONTOGENETIC SNOW BAND TO MUCH OF THE AREA ON MONDAY...WITH
POTENTIALLY SOME MODERATE TO HEAVY SNOW IN LA CROSSE. HOWEVER...THE
NAM HAS BEEN CONSIDERED AN OUTLIER SOLUTION. FOR THE WESTERN GROUP
OF THE CANADIAN/GFS...THIS GROUP WOULD ONLY BRING SOME LIGHT SNOW TO
A PORTION OF NORTHEAST IOWA AND THE AUSTIN AREA SUNDAY NIGHT. THE
SNOW THEN EXPANDS EAST A LITTLE ON MONDAY AND EXITS TO THE SOUTHEAST
TUESDAY AFTERNOON. FINALLY THE UKMET/ECMWF ARE KIND OF A COMPROMISE
BETWEEN THE GFS/CANADIAN AND THE NAM.
GIVEN THE DEFINITE SLOW DOWN SIGNAL PRESENT IN ALL MODELS WITH THE
UPPER TROUGH...HAVE TRENDED THE FORECAST THIS WAY. THE RESULT IS TO
THE KEEP THE HIGHEST PRECIPITATION CHANCES IN THE FAR WEST
SOUTHEASTERN MINNESOTA COUNTIES INTO NORTHEAST IOWA FOR LATE SUNDAY
NIGHT THROUGH TUESDAY...WITH LOWER CHANCES TO PRACTICALLY DRY BY THE
TIME YOU HEAD EAST TOWARDS I-94. APPEARS THERE COULD BE TWO
PERIODS OF MORE MODERATE SNOWFALL...ONE WITH THE INITIAL WAVE OF
FRONTOGENESIS/WARM ADVECTION...THEN THE SECOND AND FINAL ONE
ACCOMPANYING THE UPPER TROUGH AS IT DIGS SOUTH INTO MISSOURI ON
TUESDAY.
STILL GIVEN THE MODEL VARIABILITY...IT IS HARD TO SPECULATE ON
SNOWFALL AMOUNTS. ONE CONCERN IS THAT THE MAXIMUM QPF WHEREVER THE
FRONTOGENESIS BAND LAYS UP COULD END UP AT OR ABOVE 1 INCH...
ACCORDING TO THE CANADIAN...GFS...NAM AND SREF. THE ECMWF SUGGEST
HALF OF THAT...BUT THE LOWER TOTAL MAY BE A RESULT OF THE 80 KM
HORIZONTAL RESOLUTION AS WELL AS WEAKER FORCING. THE LIQUID QPF
COMBINED WITH SNOW TO WATER RATIOS LIKELY IN THE 10-15 TO 1 RANGE
FOR THIS EVENT WOULD RESULT IN 36 HOUR TOTALS OF 10 TO 12
INCHES...POSSIBLY MORE. THUS...A WINTER STORM WATCH MAY BE REQUIRED.
RIGHT NOW CONFIDENCE IS JUST NOT HIGH ENOUGH TO ISSUE THE WATCH
BECAUSE OF PLACEMENT PROBLEMS WITH THE SNOW BAND.
3. TEMPERATURES THROUGHOUT THE SHORT TERM...
TEMPERATURES TODAY LOOK TO END UP SIMILAR TO YESTERDAY GIVEN PLENTY
OF SUN BUT THE COOLER START AND 850MB TEMPS HOLDING NEARLY STEADY.
TONIGHT COULD GET QUITE CHILLY...PRIMARILY OVER WISCONSIN WHERE THE
MID/HIGH CLOUDS TAKE LONGER TO ARRIVE. STAYED TOWARDS THE COOL SIDE
OF GUIDANCE OVER WISCONSIN. THE DIURNAL CHANGE SHRINKS FOR SUNDAY
THROUGH MONDAY NIGHT...THOUGH READINGS DO LOOK WARMER... WITH PLENTY
OF CLOUDS AROUND FROM THE SYSTEM AFFECTING THE AREA. WENT WITH A
BLEND OF GUIDANCE FOR HIGHS/LOWS SUNDAY THROUGH MONDAY NIGHT.
.LONG TERM...TUESDAY NIGHT THROUGH FRIDAY NIGHT
215 AM CST SAT MAR 2 2013
MODEL AGREEMENT AMONGST THE 02.00Z ECMWF/CANADIAN/GFS AND GFS
ENSEMBLES IS PRETTY GOOD THROUGH THE LONG TERM PERIOD. GENERAL IDEA
IS THAT THE UPPER TROUGH AFFECTING THE AREA ON TUESDAY WILL HEAD
SOUTHEAST INTO THE MID-ATLANTIC REGION BY WEDNESDAY...PUSHED ALONG
BY UPPER RIDGING BUILDING EAST/NORTH INTO THE PLAINS. THUS...DRIER
CONDITIONS ARE ANTICIPATED ACROSS THE ENTIRE AREA FOR TUESDAY NIGHT
INTO WEDNESDAY.
DEFINITE PATTERN SHIFT FORECAST THROUGH THE REST OF THE WEEK WITH
TROUGHING OVER THE WESTERN U.S. AND RIDGING SHIFTING EAST AND
BUILDING OVER THE EASTERN U.S.. IN ADDITION...IT APPEARS THE UPPER
TROUGHING IN THE WESTERN U.S. IS EVENTUALLY GOING TO SPLIT INTO
TWO...WITH THE SOUTHERN PART CUTTING OFF IN THE SOUTHWEST U.S. AND
THE NORTHERN PART BRINGING A COLD FRONT THROUGH THE AREA COME
FRIDAY. PERHAPS WE MAY SEE SOME LIGHT PRECIPITATION WITH THIS
FRONTAL PASSAGE THURSDAY NIGHT INTO FRIDAY...BUT THE FRONT IS
MOISTURE AND FORCING STARVED. THUS...ONLY HAVE 20 PERCENT CHANCES AT
THE PRESENT TIME. OTHERWISE...DRY CONDITIONS PREVAIL. TEMPERATURES
ARE GOING TO BE ON THE RISE AS WELL...ESPECIALLY COME FRIDAY AHEAD
OF THE COLD FRONT. BY FRIDAY...HIGHS APPEAR ABOVE NORMAL. EVEN
BEHIND THE FRONT LOOKING AHEAD TO THE WEEKEND...THE AIRMASS DOES NOT
LOOK THAT COLD GIVEN A PACIFIC FLOW OF AIR IN ITS WAKE.
&&
.AVIATION...TODAY AND TONIGHT
518 AM CST SAT MAR 2 2013
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. HIGH
PRESSURE WILL SLIDE OVER THE TAF SITES TODAY PROVIDING MOSTLY
SUNNY SKIES AND LIGHT NORTHERLY WINDS. LINGERING LOW LEVEL
MOISTURE ACROSS THE AREA COULD LEAD TO A FEW CUMULUS TODAY WITH
CLOUD BASES AROUND 2 KFT. A STORM SYSTEM MOVING INTO THE HIGH
PLAINS TONIGHT INTO SUNDAY WILL SPREAD HIGH/MID LEVEL CLOUDS INTO
TO THE AREA TONIGHT WITH CLOUD BASES IN THE 10 KFT TO 15 KFT
RANGE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
215 AM CST SAT MAR 2 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1205 PM CST SAT MAR 2 2013
.DISCUSSION...
ISSUED 1049 AM CST SAT MAR 2 2013
NORTHERLY WINDS MOVING IN OVER THE FA WITH A NARROW RIDGE OF HIGH
PRESSURE JUST TO THE WEST OF THE MISS RIVER VALLEY SLOWLY
ADVANCING INTO THE MIDWEST. PERSISTENT CLOUDS FROM THE LAST FEW
DAYS SLOWLY RETREATING WEST TO EAST THIS MORNING. HAVE MADE A FEW
TWEAKS TO THE FORECAST FOR THE END TO THE FLURRIES FOR THE
AFTERNOON...THE RETREAT OF THE CLOUDS AND SOME MINOR UPDATES TO
THE HOURLY TEMPS. ALL IN ALL...NO MAJOR ADJUSTMENTS TO THE SHORT
TERM...AND NO ZONE UPDATES ARE NECESSARY AT THIS TIME.
&&
.AVIATION...
ISSUED 1202 PM CST SAT MAR 2 2013
SFC RIDGE SLOWLY ADVANCING INTO THE MISS RIVER VALLEY...N/NWRLY
WINDS DOMINATING...BUT WILL LIGHTEN IN THE OVERNIGHT HOURS.
CLEARING THE STRATUS THIS AFTERNOON FROM WEST TO EAST FOR ILX
TERMINALS. SCT CIRRUS WILL REMAIN...AND SOME MID LEVEL MOISTURE
COULD RESULT IN SOME SCT MID LEVEL CLOUDS AFTER MIDNIGHT. LIGHTER
WINDS IN THE OVERNIGHT AND SOME EFFICIENT RADIATIONAL COOLING MAY
ADD TO THE THREAT FOR SOME MINOR VIS REDUCTIONS FOR PIA AND BMI.
WILL WATCH THIS AFTERNOONS XOVER TEMPS FOR ADDING IN A FEW HOURS
TOWARDS DAWN IF NECESSARY.
HJS
&&
.PREV DISCUSSION...
ISSUED 240 AM CST SAT MAR 2 2013
PESKY LONG-LASTING LIGHT SNOW IS FINALLY BEGINNING TO EXIT THE
AREA...AND WAS MAINLY SOUTH OF I-70 EARLY THIS MORNING. LOW CLOUD
DECK HAS BEEN ERODING FROM THE NORTH AND SOME BREAKS HAVE
DEVELOPED AS FAR SOUTH AS PEORIA...BUT STILL PLENTY OF CLOUDINESS
OVER THE AREA.
MAIN FORECAST CONCERNS INVOLVE PRECIPITATION CHANCES EARLY NEXT
WEEK.
SHORT TERM...TODAY THROUGH TUESDAY...
MOSTLY DRY CONDITIONS EXPECTED TODAY FOR A CHANGE. WILL NEED TO
MONITOR FOR SOME LINGERING LIGHT SNOW SHOWERS ACROSS THE EASTERN
CWA TODAY...ESPECIALLY WITH THE WIND TRAJECTORY COMING OFF LAKE
MICHIGAN. CLOUDS MAY BE A BIT SLOWER TO ERODE...WITH 925-850 MB
HUMIDITY PLOT OFF THE RAP MODEL KEEPING A FAIR AMOUNT OF
CLOUDINESS EAST OF I-55 WELL INTO THE AFTERNOON. HOWEVER...
CLEARING LATER TODAY AND TONIGHT WILL PRECEDE A RIDGE OF HIGH
PRESSURE THAT WILL CROSS THE STATE ON SUNDAY.
DEEP UPPER TROUGHING OVER THE EASTERN U.S. TO PUSH EASTWARD ON
SUNDAY...AS A SHORTWAVE IN SOUTHWEST CANADA BEGINS TO CLOSE OFF
AND DROP INTO THE NORTHERN PLAINS EARLY NEXT WEEK. PRECIP CHANCES
EARLY NEXT WEEK WILL FOCUS ON A COUPLE FEATURES. THE FIRST WILL BE
WITH THE STRONG WARM AIR ADVECTION THAT WILL TAKE PLACE LATE
SUNDAY NIGHT...WITH EVENING MODELS IN FAIRLY GOOD AGREEMENT IN
DEVELOPMENT OF SOME LIGHT SNOW ACROSS THE WESTERN CWA AFTER
MIDNIGHT...AND SPREADING OVER MUCH OF THE CWA ON MONDAY. SHOULD
SEE SOME TRANSITION OVER TO RAIN DURING THE DAY ACROSS THE SOUTH
HALF OF THE FORECAST AREA...AS TEMPERATURES RISE TO AROUND THE 40
DEGREE MARK. SECOND FOCUS WILL BE AS LOW PRESSURE DEVELOPS OVER
THE CENTRAL PLAINS AND TOWARD THE WESTERN OHIO VALLEY BY TUESDAY
MORNING...WITH AN INVERTED SURFACE TROUGH EXTENDING NORTHWEST
TOWARD THE UPPER LOW. HAVE MAINTAINED HEALTHY PRECIP CHANCES
THROUGH TUESDAY WITH THESE FEATURES...MOSTLY AS SNOW BUT WITH SOME
RAIN ACROSS THE SOUTHEAST. POTENTIAL EXISTS FOR ANOTHER 1 TO 3
INCHES OF SNOW EARLY NEXT WEEK.
LONG TERM...WEDNESDAY THROUGH FRIDAY...
UPPER LOW SHOULD MAKE SOME STEADY PROGRESS SOUTHEAST AND FORM A
STRONG STORM SYSTEM OFF THE CAROLINA COAST BY MIDWEEK. THIS WILL
ALLOW FOR SOME UPPER RIDGING ACROSS THE CENTER OF THE NATION...
WITH MODERATING TEMPERATURES AS A SOUTHWEST UPPER FLOW SETS UP
LATER IN THE WEEK...AND HIGHS ARE LIKELY TO RETURN TO THE 50S BY
FRIDAY. ANY PRECIPITATION IS EXPECTED TO HOLD OFF UNTIL NEXT
WEEKEND...BEYOND THE CURRENT FORECAST PERIOD.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1052 AM CST SAT MAR 2 2013
.DISCUSSION...
ISSUED 1049 AM CST SAT MAR 2 2013
NORTHERLY WINDS MOVING IN OVER THE FA WITH A NARROW RIDGE OF HIGH
PRESSURE JUST TO THE WEST OF THE MISS RIVER VALLEY SLOWLY
ADVANCING INTO THE MIDWEST. PERSISTENT CLOUDS FROM THE LAST FEW
DAYS SLOWLY RETREATING WEST TO EAST THIS MORNING. HAVE MADE A FEW
TWEAKS TO THE FORECAST FOR THE END TO THE FLURRIES FOR THE
AFTERNOON...THE RETREAT OF THE CLOUDS AND SOME MINOR UPDATES TO
THE HOURLY TEMPS. ALL IN ALL...NO MAJOR ADJUSTMENTS TO THE SHORT
TERM...AND NO ZONE UPDATES ARE NECESSARY AT THIS TIME.
HJS
&&
.AVIATION...
ISSUED 556 AM CST SAT MAR 2 2013
PREDOMINANTLY VFR CONDITIONS EXPECTED ACROSS THE CENTRAL ILLINOIS
TERMINALS THROUGH THE 12Z TAF VALID TIME. THE PERSISTENT AREA OF
LOW CLOUDINESS...AS WELL AS A FEW FLURRIES...WILL GRADUALLY MOVE
OUT OF THE AREA TODAY AS HIGH PRESSURE STARTS TO BUILD ACROSS THE
TERMINALS. NORTHERLY WINDS TO THE EAST OF THE RIDGE AXIS SHOULD
TREND LIGHT/VARIABLE TONIGHT WITH THE APPROACH OF THE RIDGE.
BAK
&&
.PREV DISCUSSION...
ISSUED 240 AM CST SAT MAR 2 2013
PESKY LONG-LASTING LIGHT SNOW IS FINALLY BEGINNING TO EXIT THE
AREA...AND WAS MAINLY SOUTH OF I-70 EARLY THIS MORNING. LOW CLOUD
DECK HAS BEEN ERODING FROM THE NORTH AND SOME BREAKS HAVE
DEVELOPED AS FAR SOUTH AS PEORIA...BUT STILL PLENTY OF CLOUDINESS
OVER THE AREA.
MAIN FORECAST CONCERNS INVOLVE PRECIPITATION CHANCES EARLY NEXT
WEEK.
SHORT TERM...TODAY THROUGH TUESDAY...
MOSTLY DRY CONDITIONS EXPECTED TODAY FOR A CHANGE. WILL NEED TO
MONITOR FOR SOME LINGERING LIGHT SNOW SHOWERS ACROSS THE EASTERN
CWA TODAY...ESPECIALLY WITH THE WIND TRAJECTORY COMING OFF LAKE
MICHIGAN. CLOUDS MAY BE A BIT SLOWER TO ERODE...WITH 925-850 MB
HUMIDITY PLOT OFF THE RAP MODEL KEEPING A FAIR AMOUNT OF
CLOUDINESS EAST OF I-55 WELL INTO THE AFTERNOON. HOWEVER...
CLEARING LATER TODAY AND TONIGHT WILL PRECEDE A RIDGE OF HIGH
PRESSURE THAT WILL CROSS THE STATE ON SUNDAY.
DEEP UPPER TROUGHING OVER THE EASTERN U.S. TO PUSH EASTWARD ON
SUNDAY...AS A SHORTWAVE IN SOUTHWEST CANADA BEGINS TO CLOSE OFF
AND DROP INTO THE NORTHERN PLAINS EARLY NEXT WEEK. PRECIP CHANCES
EARLY NEXT WEEK WILL FOCUS ON A COUPLE FEATURES. THE FIRST WILL BE
WITH THE STRONG WARM AIR ADVECTION THAT WILL TAKE PLACE LATE
SUNDAY NIGHT...WITH EVENING MODELS IN FAIRLY GOOD AGREEMENT IN
DEVELOPMENT OF SOME LIGHT SNOW ACROSS THE WESTERN CWA AFTER
MIDNIGHT...AND SPREADING OVER MUCH OF THE CWA ON MONDAY. SHOULD
SEE SOME TRANSITION OVER TO RAIN DURING THE DAY ACROSS THE SOUTH
HALF OF THE FORECAST AREA...AS TEMPERATURES RISE TO AROUND THE 40
DEGREE MARK. SECOND FOCUS WILL BE AS LOW PRESSURE DEVELOPS OVER
THE CENTRAL PLAINS AND TOWARD THE WESTERN OHIO VALLEY BY TUESDAY
MORNING...WITH AN INVERTED SURFACE TROUGH EXTENDING NORTHWEST
TOWARD THE UPPER LOW. HAVE MAINTAINED HEALTHY PRECIP CHANCES
THROUGH TUESDAY WITH THESE FEATURES...MOSTLY AS SNOW BUT WITH SOME
RAIN ACROSS THE SOUTHEAST. POTENTIAL EXISTS FOR ANOTHER 1 TO 3
INCHES OF SNOW EARLY NEXT WEEK.
LONG TERM...WEDNESDAY THROUGH FRIDAY...
UPPER LOW SHOULD MAKE SOME STEADY PROGRESS SOUTHEAST AND FORM A
STRONG STORM SYSTEM OFF THE CAROLINA COAST BY MIDWEEK. THIS WILL
ALLOW FOR SOME UPPER RIDGING ACROSS THE CENTER OF THE NATION...
WITH MODERATING TEMPERATURES AS A SOUTHWEST UPPER FLOW SETS UP
LATER IN THE WEEK...AND HIGHS ARE LIKELY TO RETURN TO THE 50S BY
FRIDAY. ANY PRECIPITATION IS EXPECTED TO HOLD OFF UNTIL NEXT
WEEKEND...BEYOND THE CURRENT FORECAST PERIOD.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1119 AM CST SAT MAR 2 2013
.AVIATION...
VFR CONDITIONS THROUGH 03/18Z. HIGH PRESSURE WILL MOVE OVERHEAD
TONIGHT KEEPING SKIES CLEAR TO MOSTLY CLEAR WITH LIGHT WINDS INTO
MID MORNING ON SUNDAY. A DEVELOPING STORM SYSTEM IN THE NORTHERN
PLAINS WILL MOVE SOUTHEAST ON SUNDAY SPREADING INCREASING HIGH
CLOUDS ACROSS ALL THE TERMINALS TOWARD SUNRISE AND ESPECIALLY
SUNDAY MORNING. WINDS WILL SHIFT TO THE SOUTHEAST AT LESS THAN 10
KTS AFTER SUNRISE. CEILINGS WILL CONTINUE TO LOWER AFTER 18Z
SUNDAY AS THE STORM SYSTEM APPROACHES.
NICHOLS
&&
.PREV DISCUSSION... /ISSUED 324 AM CST SAT MAR 2 2013/
SYNOPSIS...
LATEST IR SATELLITE IMAGERY INDICATED THE NORTH TO SOUTH CLEARING
TREND OF LOW CLOUDS HAD COME TO A HALT ROUGHLY ALONG THE I-80
CORRIDOR OVER THE PAST FEW HOURS. SURFACE ANALYSIS INDICATED A LEE
TROUGH ACROSS THE WESTERN HIGH PLAINS FLANKED BY HIGH PRESSURE
REACHING FROM THE EASTERN DAKOTAS TO KS. OVER THE LOCAL AREA...A
LIGHT N-NE 925 MB AND 850 MB FLOW CONTINUED TO FEED MOISTURE FROM
THE GREAT LAKES...AND DEPARTING STORM SYSTEM INTO ESPECIALLY THE IL
SIDE OF THE FORECAST AREA. THIS TRAJECTORY SHOULD FINALLY BREAK DOWN
TODAY AS THE WESTERN U.S. UPPER RIDGE BUILDS AND EDGES EASTWARD...
PUSHING THE SURFACE RIDGE...AND A WEAK MID LEVEL ANTICYCLONE OVER
SOUTHERN LAKE MI EASTWARD.
SHORT TERM...TODAY AND TONIGHT...
MAIN CHALLENGES ARE CENTERED ON CLOUD AND TEMPERATURE TRENDS. SHORT
TERM MODELS GENERALLY DEPICT THE MOISTURE LAYER AROUND 925 MB
ASSOCIATED WITH THE STRATUS DECK...THAT WAS COVERING MUCH OF WESTERN
AND SOUTHERN IA...SHIFTING SOUTHWARD TODAY. EAST OF THE MS
RIVER...THE EXTENSIVE STRATUS DECK IS SHOWN MAKING A WESTWARD
RESURGENCE IN THE AFTERNOON AFTER CLEARING THIS MORNING. THIS IS
MOST PRONOUNCED IN THE LATEST RAP RH FIELDS. FOR NOW...WILL KEEP A
MORE OPTIMISTIC FORECAST OF MOSTLY SUNNY SKIES OVER THE ENTIRE AREA
BY AFTERNOON...COUNTING ON THE EFFECTS OF INCREASING MID LEVEL
SUBSIDENCE WITH THE INCOMING UPPER LEVEL RIDGE. EVEN WITH
SUNSHINE...LOOKING AT HIGHS FROM UPSTREAM YESTERDAY AND CONSIDERING
925 MB TEMPERATURES THAT WILL BE SIMILAR TO YESTERDAY...HIGHS FROM
THE UPPER 20S NORTH TO LOWER 30S LOOK REASONABLE.
TONIGHT...THE SURFACE RIDGE TO THE WEST WEAKENS AS IT PASSES THROUGH
THE AREA ALLOWING WINDS TO BECOME LIGHT AND VARIABLE TOWARD MORNING.
SKIES SHOULD INITIALLY BE MOSTLY CLEAR...BUT THERE WILL BE A THREAT
OF INCREASING HIGH CLOUDS IN THE NW FLOW ALOFT. THIS WOULD PREVENT
TEMPERATURES FROM BOTTOMING OUT OVER OUR EXTENSIVE SNOWFIELD AND
FOR NOW WILL COUNT ON THIS OCCURRING TO HOLD MINS NO LOWER THAN
AROUND 10 NORTH TO THE MID TEENS SOUTH. IF HIGH CLOUDS DO NOT
MATERIALIZE...WIDESPREAD SINGLE DIGITS WOULD BE LIKELY...SIMILAR
TO WHAT IS OCCURRING THIS MORNING.
SHEETS
LONG TERM...SUNDAY THROUGH FRIDAY...
SUNDAY NIGHT THROUGH TUESDAY...THE NEXT SYSTEM TO AFFECT THE UPPER
MISSISSIPPI VALLEY WILL OCCUR SUNDAY NIGHT THROUGH TUESDAY. MODEL
FORECASTS ARE INCONSISTENT WITH LARGE DIFFERENCES NOTED IN THE
PLACEMENT OF THE UPPER LOW. 06Z SATURDAY WATER VAPOR SATELLITE
IMAGERY SHOWS THE SYSTEM IS CURRENTLY OVER THE GULF OF ALASKA. MODEL
SOLUTIONS WILL LIKELY CONTINUE TO BE INCONSISTENT UNTIL THE WAVE
MOVES ONSHORE AND GETS BETTER SAMPLED BY THE UPPER AIR NETWORK. AT
12Z MONDAY ALL MODELS SHOW THE UPPER LOW OVER MONTANA BUT LARGE
DIFFERENCE IN PLACEMENT OCCUR AFTER THAT. BY 18Z TUESDAY THE NAM
MOVES THE UPPER LOW FROM MONTANA TO SOUTHERN MINNESOTA...THE
ECMWF/DGEX MOVE THE UPPER LOW ACROSS IOWA/ILLINOIS WHILE THE GFS
TAKES THE LOW SOUTH OF THE REGION ACROSS MISSOURI. EVEN WITH THE
UPPER LOW PLACEMENT PROBLEMS...ALL MODELS SHOW AN ELEVATED WARM
ADVECTION WING AHEAD OF THE SYSTEM WHICH WOULD BREAK OUT SNOW ACROSS
THE AREA BEFORE DAYBREAK MONDAY MORNING. FOR NOW I HAVE HAVE KEPT
CURRENT FORECAST CHANCE POPS FOR SUNDAY NIGHT BUT RAISED POPS TO
LIKELY CATEGORY FOR MONDAY MORNING. SNOW WILL CONTINUE INTO TUESDAY
AS UPPER FORCING INCREASES AS THE UPPER LOW MOVES CROSSES OVER OR
NEAR THE REGION.
BOTTOM LINE...CONFIDENCE IS HIGH SNOW WILL FALL IN OR NEAR OUR
FORECAST AREA MONDAY AND TUESDAY. CONFIDENCE IS LOW AS TO SPECIFIC
LOCATION AND TOTAL SNOW AMOUNTS.
WEDNESDAY THROUGH FRIDAY...LATER IN THE WEEK THE UPPER AIR PATTERN
SHIFTS TO A SOUTHWESTERLY FLOW AS AN UPPER LEVEL RIDGE LOCATED OVER
THE ROCKIES BEGINS TO MOVE EAST. SURFACE WINDS WILL BE SOUTHERLY
COMING AROUND THE WEST SIDE OF HIGH PRESSURE LOCATED OVER THE GREAT
LAKES/OHIO VALLEY. TEMPERATURES SHOULD BE CLOSE TO NORMAL THURSDAY
AND COULD EVEN BE ABOVE NORMAL BY FRIDAY. THE END OF NEXT WEEK LOOKS
TO BE DRY.
KUHL
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
NICHOLS
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1037 AM MST SAT MAR 2 2013
.UPDATE...
ISSUED AT 941 AM MST SAT MAR 2 2013
JUST COMPLETED AN UPDATE. FIRST INCREASED CLOUD COVER THROUGH THE
DAY. THIS ADJUSTED TONIGHTS AND SUNDAYS CLOUD COVER PER LATEST
GUIDANCE AND TRENDS. DESPITE THE CLOUD COVER...TEMPERATURES ARE
RAPIDLY RISING ESPECIALLY IN THE WEST. MIXING APPEARS TO BE BETTER
THAN MOST MODEL OUTPUT SINCE THE MODELS PERCEIVED SNOW COVER IS
OVER AFFECTING ITS FORECAST. HRRR CONFIRMED BY LATEST 850 MB
TEMPERATURE GUIDANCE IS CATCHING THIS VERY WELL AND USED THEM FOR
THE UPDATE. WILL PROBABLY HAVE TO RAISE TOMORROWS MAXES PER TODAYS
TRENDS AND GUIDANCE. ALSO USED THE HRRR WINDS FOR THE REST OF THE
DAY AS WELL.
&&
.SHORT TERM...(TODAY AND MONDAY NIGHT)
ISSUED AT 247 AM MST SAT MAR 2 2013
SHORT TERM FORECAST CONCERNS ARE THE WARM TEMPERATURES THROUGH THE
WEEKEND FOLLOWED BY COOLER TEMPERATURES AND WINDY CONDITIONS ON
MONDAY.
MODELS ARE IN REASONABLE AGREEMENT...BUT BEGIN TO DIVERGE BY
MONDAY NIGHT AS THE APPROACHING UPPER LOW CENTER MOVES EAST OF THE
ROCKIES.
THE LARGE UPPER RIDGE CURRENTLY OVER THE WESTERN UNITED STATES
WILL MOVE EAST OVER THE ROCKIES AND HIGH PLAINS TODAY AND TONIGHT
AS IT BEGINS TO FLATTEN WITH THE APPROACH OF A LOW CENTER OVER THE
PACIFIC NORTHWEST. THE UPPER FLOW OVER THE CENTRAL HIGH PLAINS
CONTINUES TO FLATTEN THROUGH SUNDAY AND SUNDAY NIGHT AS THE UPPER
LOW MOVES INTO THE NORTHERN HIGH PLAINS BY EARLY MONDAY MORNING.
SURFACE FLOW ACROSS THE FORECAST AREA THROUGH EARLY SUNDAY WILL
BE OUT OF THE SOUTHWEST TO WEST AHEAD OF THE DEEPENING SURFACE LEE
TROUGH WITH WARMER TEMPERATURES GENERALLY OVER THE WEST AND
COOLER TEMPERATURES IN THE EASTERN SECTIONS WHERE THE SNOW COVER
WILL STILL AFFECT DAYTIME TEMPERATURES. A COLD FRONT PUSHES INTO
THE REGION EARLY MONDAY MORNING AHEAD OF THE UPPER LOW...WITH GUSTY
NORTHWEST WINDS EXPECTED THROUGH THE DAY ON MONDAY BEHIND THE
FRONT. HAVE KEPT WIND SPEEDS BELOW ADVISORY CRITERIA FOR NOW AS
WIND SPEED VALUES ARE FLIP-FLOPPING SOMEWHAT WITH EACH RUN. THE UPPER
LOW MOVES INTO THE CENTRAL PLAINS STATES OVERNIGHT MONDAY NIGHT.
MODELS ARE HINTING AT POSSIBLE PRECIPITATION MONDAY INTO MONDAY
NIGHT...BUT HAVE SO FAR KEPT DRY CONDITIONS IN THE FORECAST AND
NUDGED THE POPS SLIGHTLY HIGHER DURING THAT PERIOD.
.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 247 AM MST SAT MAR 2 2013
TUESDAY-SATURDAY...H5 RIDGE BUILDS BACK OVER CWA WITH DRY CONDITIONS
AND WARMING TREND THROUGH THE PERIODS. TUESDAY SHOULD BE BELOW
NORMAL WITH NORTHERLY FLOW STILL IN PLACE AND COOL AIR MASS
LINGERING. CURRENTLY EXPECTING HIGHS IN THE UPPER 30S TO MID 40S FROM
EAST TO WEST. WARMING TREND KICKS IN ON WED WHEN HIGHS COULD BE
NEAR 60F ACROSS WESTERN LOCATIONS. HIGHS ON THU SHOULD BE IN THE 60S
ACROSS MOST OF THE CWA. LARGE SCALE TROUGH WITH CLOSED CENTER IS
PROGGED TO DEVELOP OVER THE FOUR CORNERS REGION. A COLD FRONT IS
EXPECTED TO DROP SOUTH OVER THE CWA FRI OR FRI NIGHT WHICH SHOULD
BRING TEMPS BACK TO SEASONAL VALUES NEAR 50F. TROUGH WILL STILL BE
WELL WEST OF CWA...HOWEVER GUIDANCE IS SHOWING DECENT FORCING AND
MOISTURE SPREADING OUT AHEAD OF THE MAIN TROUGH...WITH
SHOWERS/THUNDERSTORMS POSSIBLE OVER CENTRAL KS AHEAD OF COLD FRONT.
CURRENT GUIDANCE KEEPS BETTER CHANCES SOUTH AND EAST DURING THE DAY
FRI...SO I KEPT FORECAST DRY FOR NOW.
GUIDANCE SHOWS BETTER PRECIP CHANCES FRI NIGHT THROUGH SAT NIGHT
WHICH IS OUTSIDE THE VALID FORECAST PERIOD. THE CLOSED LOW OVER THE
FOUR CORNERS REGION IS PROGGED TO MOVE INTO THE PLAINS...WITH QUITE
A BIT OF SPREAD BETWEEN MODELS ON HOW THIS SYSTEM EVOLVES...AND
WHERE IT TRACKS. BECAUSE OF THIS...CONFIDENCE IS LOW ON WHAT IMPACTS
WE CAN ANTICIPATE OVER OUR CWA. FOR NOW GUIDANCE WOULD AT LEAST
INDICATE A STRONG STORM SYSTEM IMPACTING THE SOUTHERN OR CENTRAL
PLAINS NEXT WEEKEND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1037 AM MST SAT MAR 2 2013
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...BULLER
SHORT TERM...LOCKHART
LONG TERM...DR
AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
947 AM MST SAT MAR 2 2013
.UPDATE...
ISSUED AT 941 AM MST SAT MAR 2 2013
JUST COMPLETED AN UPDATE. FIRST INCREASED CLOUD COVER THROUGH THE
DAY. THIS ADJUSTED TONIGHTS AND SUNDAYS CLOUD COVER PER LATEST
GUIDANCE AND TRENDS. DESPITE THE CLOUD COVER...TEMPERATURES ARE
RAPIDLY RISING ESPECIALLY IN THE WEST. MIXING APPEARS TO BE BETTER
THAN MOST MODEL OUTPUT SINCE THE MODELS PERCEIVED SNOW COVER IS
OVER AFFECTING ITS FORECAST. HRRR CONFIRMED BY LATEST 850 MB
TEMPERATURE GUIDANCE IS CATCHING THIS VERY WELL AND USED THEM FOR
THE UPDATE. WILL PROBABLY HAVE TO RAISE TOMORROWS MAXES PER TODAYS
TRENDS AND GUIDANCE. ALSO USED THE HRRR WINDS FOR THE REST OF THE
DAY AS WELL.
&&
.SHORT TERM...(TODAY AND MONDAY NIGHT)
ISSUED AT 247 AM MST SAT MAR 2 2013
SHORT TERM FORECAST CONCERNS ARE THE WARM TEMPERATURES THROUGH THE
WEEKEND FOLLOWED BY COOLER TEMPERATURES AND WINDY CONDITIONS ON
MONDAY.
MODELS ARE IN REASONABLE AGREEMENT...BUT BEGIN TO DIVERGE BY
MONDAY NIGHT AS THE APPROACHING UPPER LOW CENTER MOVES EAST OF THE
ROCKIES.
THE LARGE UPPER RIDGE CURRENTLY OVER THE WESTERN UNITED STATES
WILL MOVE EAST OVER THE ROCKIES AND HIGH PLAINS TODAY AND TONIGHT
AS IT BEGINS TO FLATTEN WITH THE APPROACH OF A LOW CENTER OVER THE
PACIFIC NORTHWEST. THE UPPER FLOW OVER THE CENTRAL HIGH PLAINS
CONTINUES TO FLATTEN THROUGH SUNDAY AND SUNDAY NIGHT AS THE UPPER
LOW MOVES INTO THE NORTHERN HIGH PLAINS BY EARLY MONDAY MORNING.
SURFACE FLOW ACROSS THE FORECAST AREA THROUGH EARLY SUNDAY WILL
BE OUT OF THE SOUTHWEST TO WEST AHEAD OF THE DEEPENING SURFACE LEE
TROUGH WITH WARMER TEMPERATURES GENERALLY OVER THE WEST AND
COOLER TEMPERATURES IN THE EASTERN SECTIONS WHERE THE SNOW COVER
WILL STILL AFFECT DAYTIME TEMPERATURES. A COLD FRONT PUSHES INTO
THE REGION EARLY MONDAY MORNING AHEAD OF THE UPPER LOW...WITH GUSTY
NORTHWEST WINDS EXPECTED THROUGH THE DAY ON MONDAY BEHIND THE
FRONT. HAVE KEPT WIND SPEEDS BELOW ADVISORY CRITERIA FOR NOW AS
WIND SPEED VALUES ARE FLIP-FLOPPING SOMEWHAT WITH EACH RUN. THE UPPER
LOW MOVES INTO THE CENTRAL PLAINS STATES OVERNIGHT MONDAY NIGHT.
MODELS ARE HINTING AT POSSIBLE PRECIPITATION MONDAY INTO MONDAY
NIGHT...BUT HAVE SO FAR KEPT DRY CONDITIONS IN THE FORECAST AND
NUDGED THE POPS SLIGHTLY HIGHER DURING THAT PERIOD.
.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 247 AM MST SAT MAR 2 2013
TUESDAY-SATURDAY...H5 RIDGE BUILDS BACK OVER CWA WITH DRY CONDITIONS
AND WARMING TREND THROUGH THE PERIODS. TUESDAY SHOULD BE BELOW
NORMAL WITH NORTHERLY FLOW STILL IN PLACE AND COOL AIR MASS
LINGERING. CURRENTLY EXPECTING HIGHS IN THE UPPER 30S TO MID 40S FROM
EAST TO WEST. WARMING TREND KICKS IN ON WED WHEN HIGHS COULD BE
NEAR 60F ACROSS WESTERN LOCATIONS. HIGHS ON THU SHOULD BE IN THE 60S
ACROSS MOST OF THE CWA. LARGE SCALE TROUGH WITH CLOSED CENTER IS
PROGGED TO DEVELOP OVER THE FOUR CORNERS REGION. A COLD FRONT IS
EXPECTED TO DROP SOUTH OVER THE CWA FRI OR FRI NIGHT WHICH SHOULD
BRING TEMPS BACK TO SEASONAL VALUES NEAR 50F. TROUGH WILL STILL BE
WELL WEST OF CWA...HOWEVER GUIDANCE IS SHOWING DECENT FORCING AND
MOISTURE SPREADING OUT AHEAD OF THE MAIN TROUGH...WITH
SHOWERS/THUNDERSTORMS POSSIBLE OVER CENTRAL KS AHEAD OF COLD FRONT.
CURRENT GUIDANCE KEEPS BETTER CHANCES SOUTH AND EAST DURING THE DAY
FRI...SO I KEPT FORECAST DRY FOR NOW.
GUIDANCE SHOWS BETTER PRECIP CHANCES FRI NIGHT THROUGH SAT NIGHT
WHICH IS OUTSIDE THE VALID FORECAST PERIOD. THE CLOSED LOW OVER THE
FOUR CORNERS REGION IS PROGGED TO MOVE INTO THE PLAINS...WITH QUITE
A BIT OF SPREAD BETWEEN MODELS ON HOW THIS SYSTEM EVOLVES...AND
WHERE IT TRACKS. BECAUSE OF THIS...CONFIDENCE IS LOW ON WHAT IMPACTS
WE CAN ANTICIPATE OVER OUR CWA. FOR NOW GUIDANCE WOULD AT LEAST
INDICATE A STRONG STORM SYSTEM IMPACTING THE SOUTHERN OR CENTRAL
PLAINS NEXT WEEKEND.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 441 AM MST SAT MAR 2 2013
VFR CONDITIONS WILL PREVAIL AT GLD WITH NORTHWEST WINDS
INCREASING SLIGHTLY DURING DAYLIGHT HOURS...BECOMING LIGHT
WESTERLY AFTER SUNSET.
MCK WILL START OUT MVFR WITH CALM WINDS AND LOWER VISIBILITIES
PRODUCED BY AREAS OF FOG. AREAS OF FOG WILL DISSIPATE BY LATE
MORNING AS WESTERLY WINDS BECOME LIGHT WITH CONDITIONS BECOMING
VFR. VFR CONDITIONS WILL CONTINUE THROUGH THE REMAINDER OF THE TAF
PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...BULLER
SHORT TERM...LOCKHART
LONG TERM...DR
AVIATION...LOCKHART
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
402 PM EST SAT MAR 2 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 400 PM EST SAT MAR 2 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A RIDGE OVER THE WRN CONUS AND
AND TROUGHING OVER THE EAST...RESULTING IN NW MID/UPPER LEVEL FLOW
FROM WRN CANADA THROUGH THE PLAINS INTO THE LOWER MS VALLEY. AT THE
SFC...A RIDGE EXTENDED FROM HUDSON BAY AN NW ONTARIO THROUGH WRN
LAKE SUPERIOR. DAYTIME MIXING AND LOW LEVEL DRYING UPSTREAM
(DEWPOINT DEPRESSIONS AOA 30F) HAS SUBSTANTIALLY REDUCED THE
COVERAGE/INTENSITY OF LES INTO N CNTRL UPPER MI THIS AFTERNOON.
TONIGHT...A WEAK SHORTWAVE TROUGH TO NEAR INL WILL DIVE SE
REINFORCING THE MID LEVEL TROUGH OVER THE NRN GREAT LAKES.
HOWEVER..THE SFC RIDGE EXTENDING SOUTH FROM THE HUDSON BAY HIGH WILL
CONTINUE TO BE THE DOMINANT FEATURE OVER THE AREA. INVERSION HEIGHTS
BETWEEN 2K TO 3K FT AND THE VERY DRY AIR UPSTREAM NORTH OF LAKE
SUPERIOR...WILL HELP SUPPRESS LAKE EFFECT SNOW CHANCES/INTENSITY
DESPITE TEMPS FCST NEAR -14C AT THE BASE OF THE INVERSION.
AS LAND BREEZES DEVELOP TONIGHT...INCREASING LOW LEVEL CONVERGENCE
SHOULD STRENGTHEN LES WITH SCT -SHSN INTO NORTH CENTRAL UPPER MI FROM
MARQUETTE TO MUNISING. ANY SNOWFALL AMOUNTS...HOWEVER SHOULD BE
LIGHT AMOUNTS OF A HALF INCH OR LESS. LAKE CLOUDS ARE EXPECTED TO
LIMIT TEMP FALL OVER CNTRL AND EAST PORTIONS OF THE CWA...BUT WITH
LIGHT/CALM WINDS AND SOME CLEARING INLAND WEST...TEMPS SHOULD DROP
INTO THE SINGLE DIGITS BLO ZERO...WITH SOME LOCALLY COLDER TEMPS
POSSIBLE.
SUNDAY...SIMILAR TO TODAY...EXPECT THAT LES IN THE MORNING MAINLY
INTO N CNTRL UPPER MI WILL DIMINISH IN THE AFTERNOON WITH THE SFC
RIDGE REMAINING OVER THE REGION. EXPECT MAX TEMPERATURES TO CLIMB
INTO THE MID AND UPPER 20S AS THE ARCTIC AIRMASS SLOWLY MODIFIES.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 400 PM EST SAT MAR 2 2013
TROUGH THAT HAS BEEN STUCK OVER THE GREAT LAKES THROUGH MOST OF THIS
PAST WEEK LOOKS TO FINALLY EASE BY MID-LATE WEEK. A MORE SIGNIFICANT
SHORTWAVE TROUGH DIGS INTO THE MEAN TROUGH MONDAY THROUGH WEDNESDAY.
BASED ON TRACK OF SHORTWAVE AND H85-H5 Q-VECTOR CONVERGENCE...MOST
OF THE SNOW FROM THAT SYSTEM WILL IMPACT MOST OF MINNESOTA THROUGH
WISCONSIN AND INTO LOWER MICHIGAN. EVEN THOUGH SFC-H85 LOWS REMAIN
WELL TO SOUTH OF UPR MICHIGAN...NORTHEAST WINDS BTWN THE LOWS AND
HIGH PRESSURE OVER HUDSON BAY AND ENOUGH LOW-LEVEL MOISTURE THROUGH
H9 ALONG WITH COLD ENOUGH TEMPS AT TOP OF INVERSION SHOULD SUPPORT
LIGHT LK EFFECT THROUGH WEDNESDAY BEFORE WINDS BECOME LIGHT AND
VARIABLE. SIMILAR TO WHAT WE HAVE SEEN LATELY THE SNOW WILL BE
AROUND BUT NOT ACCUMULATE MUCH AS INVERSION HEIGHTS REMAINING
BLO 3KFT LIMIT LK EFFECT INTENSITY AND MARGINALLY COLD AIR LIMITS
FLUXES OFF THE LAKES. INCREASING MOISTURE THROWN TO NORTH OF EARLY
WEEK LOW PRESSURE SYSTEM MAY HELP ENHANCE THE SNOW SLIGHTLY MONDAY
NIGHT AND TUESDAY IN AREAS FAVORED BY NORTHEAST WINDS. PERHAPS SOME
LIGHT SNOW ACCUMULATIONS OF A FEW INCHES MAY OCCUR DURING THAT TIME.
TEMPERATURES THROUGH WEDNESDAY WILL BE GRADUALLY WARMING...BUT STILL
ONLY INTO LOWER 30S. TRICKY FORECAST NIGHTTIME LOWS SUNDAY NIGHT AS
AREAS AWAY FROM THE CLOUDS AND SNOW SHOWERS NEAR LK SUPERIOR MAY
EASILY DROP BLO ZERO. MORE CLOUDS ON MONDAY NIGHT AND TUESDAY NIGHT
SHOULD RESULT IN READINGS STAYING MOSTLY IN THE TEENS ABOVE ZERO.
HIGH PRESSURE MOVING INTO THE AREA WEDNESDAY NIGHT WILL BEGIN TO
TURN WINDS TO THE SOUTH AND WILL FINALLY END LIGHT LK EFFECT BY
THURSDAY. BY FRIDAY...UPPER LEVEL TROUGH DEVELOPS FROM WESTERN
CONUS THROUGH NORTHERN PLAINS WHILE RIDGING MOVES ACROSS GREAT LAKES
IN WAKE OF THE EARLY WEEK SYSTEM. EXPECT LOW PRESSURE TO FORM ON
LEADING EDGE OF TROUGH OVER THE PLAINS...THOUGH THE STORM SHOULD NOT
BE TOO STRONG AS LOW-LEVEL TEMPERATURE CONTRAST PRECEEDING THE
SYSTEM IS MINIMAL. GFS AND ECMWF THEN SHOW TROUGH SPLITTING BY
FRIDAY WITH SOUTHERN STREAM PORTION CLOSING OFF OVER SOUTHWEST
CONUS WHILE NORTHERN BRANCH SHORTWAVE MOVES EAST ACROSS SOUTH
CENTRAL CANADA. NORTHERN TROUGH MOVING EAST WILL DRAG THE WEAKER LOW
PRESSURE SYSTEM AND ASSOCIATED COLD FRONT ACROSS GREAT LAKES LATER
ON FRIDAY. GFS REMAINS QUICKER WITH THIS COLD FROPA COMPARED TO
ECMWF AND GEM-NH. COULD BE SOME PRECIPITATION WITH THE SYSTEM...BUT
SINCE THE H85 LOW IS OPENING UP AND BECOMING MORE PROGRESSIVE...AND
MOVING THROUGH QUICKLY...DO NOT EXPECT SIGNIFICANT PRECIPITATION.
HAVING SMALL CHANCE POPS IN THERE FOR THURSDAY NIGHT THROUGH FRIDAY
NIGHT SEEM JUSTIFIED DURING THIS TIME FRAME.
AFTER THE PERSISTENT TROUGHING KEEPS TEMPS ON THE COOLER SIDE OF
AVERAGE TO START THE WEEK...EXPECT WARMER READINGS THURSDAY INTO
FRIDAY WITH SOUTH-SOUTHWEST WINDS BTWN THE HIGH PRESSURE AND THE LOW
PRESSURE SYSTEM TO THE WEST. BASED ON 925-900MB TEMPS...SHOULD SEE
HIGHS ON THURSDAY REACH THE 30S WITH JUST A SMALL DROP IN READINGS
ON THURSDAY NIGHT IN WARM AIR ADVECTION AHEAD OF THE COLD FRONT.
TEMPERATURES ON FRIDAY PROBABLY REACH WELL INTO THE 30S. IF NOT FOR
A MOSTLY CLOUDY SKY...COULD EVEN SEE A FEW LOW-MID 40S WHERE MIXING
IS STRONGER. DID TWEAK TEMPS UPWARD NEAR LK SUPERIOR WITH DOWNSLOPE
WINDS FCST. TIGHTER PRESSURE GRADIENT WILL LEAD TO BREEZY CONDITIONS
THURSDAY NIGHT AND FRIDAY. TURNING BLUSTERY FOR SATURDAY FOLLOWING
THE COLD FRONT PASSAGE. TEMPS WILL NOT DROP TOO MUCH THOUGH...MAINLY
STAYING IN THE LOW-MID 30S...WHICH IS NEAR NORMAL FOR EARLY MARCH.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1235 PM EST SAT MAR 2 2013
LAKE EFFECT CLOUDS WITH NORTH UPSLOPE WINDS WILL BRING MVFR
CONDITIONS TO ALL TAF SITES INTO THIS EVENING. MIXING AND
INCREASINGLY DIFLUENT FLOW SHOULD ALLOW CONDITIONS TO IMPROVE AT
CMX/IWD WITH VFR CONDITIONS TONIGHT INTO SUNDAY. HOWEVER...MVFR CIGS
ARE LIKELY TO PERSIST AT SAW TONIGHT AS INCREASING LOW-LVL
CONVERGENCE LEADS TO LAKE CLOUD FORMATION/FLURRIES.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 400 PM EST SAT MAR 2 2013
WINDS LESS THAN 20 KTS THROUGH MONDAY...THEN EXPECT NORTHEAST WINDS
TO INCREASE TO 30 KTS OVER WESTERN SECTIONS BY MONDAY NIGHT AS LOW
PRESSURE SYSTEM MOVES BY TO THE SOUTH OVER THE NORTHERN MISSISSIPPI
RIVER VALLEY. WINDS 20-30 KTS CONTINUE OVER MOST OF LK SUPERIOR
THROUGH TUESDAY BEFORE SETTLING DOWN TO LESS 20 KTS BY WEDNESDAY.
WINDS INCREASE TO 25 KTS FROM THE SOUTH THURSDAY NIGHT AND FRIDAY
AHEAD OF COLD FRONT. NO GALES ARE EXPECTED THIS WEEK...THOUGH COULD
SEE GALE GUSTS OVER WESTERN LK SUPERIOR MONDAY NIGHT CLOSER TO
MINNESOTA SHORELINE DUE TO COASTAL CONVERGENCE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...JLB
MARINE...JLA
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
117 PM EST SAT MAR 2 2013
.SYNOPSIS...
ISSUED AT 315 AM EST SAT MAR 2 2013
HIGH PRESSURE WILL BRING FAIR AND DRY BUT COLD WEATHER THROUGH THE
WEEKEND. TEMPERATURES WILL UNDERGO A GRADUAL MODERATING TREND FOR
THE UPCOMING WEEK WITH TRANQUIL WEATHER EXPECTED TO CONTINUE.
&&
.UPDATE...
ISSUED AT 956 AM EST SAT MAR 2 2013
I UPDATED THE Z0NES FOR MORE CLOUDINESS INTO SUNDAY. I ALSO ADDED
FLURRIES INTO THIS EVENING. THE LATEST SATELLITE LOOPS SHOW ONLY
THE AREA NEAR AND EAST OF US-131 AND SOUTH OF BIG RAPIDS HAVING
ANY SUNSHINE. ALL OF THE MODELS SHOW THE CLOUDS WILL FILL IN THERE
TOO AS THE THERMAL TROUGH MOVES THROUGH. MOST OF THE REPORTING
STATIONS NORTH AND EAST OF GRR HAVE FLURRIES AND OUR RADAR HAS
SOME WEAK RETURNS EAST OF THE OFFICE WHICH ARE INCREASING AND
MOVING TO THE SOUTH SOUTHWEST. GIVEN THE FLURRIES ALREADY THERE AND
THE RAP MODEL SUGGESTING .03 AT GRR BTW 18Z AND 06Z IT SEEMS
PRUDENT TO PUT AT LEAST A FEW FLURRIES IN THE FORECAST. IF THE
SNOW SHOWER ACTIVITY INCREASES THAN I WILL UPDATE AGAIN.
&&
.SHORT TERM...(TODAY THROUGH MONDAY AFTERNOON)
ISSUED AT 315 AM EST SAT MAR 2 2013
HIGH PRESSURE WILL PRODUCE DRY BUT COLD WX THROUGH MONDAY WITH MAX
TEMPS THIS WEEKEND ONLY REACHING THE UPPER 20S TO LOWER 30S AND MIN
TEMPS MAINLY IN THE TEENS. SOME SINGLE DIGIT MINS ARE POSSIBLE THE
NEXT FEW NIGHTS NORTH OF I-96 GIVEN EXPANSIVE SNOW COVER AND
DEPENDENT LARGELY ON EXTENT OF CLEARING.
CURRENT IR SAT TREND CORROBORATED WITH 00Z NAM/GFS GUIDANCE TIME
HEIGHT RH PROGS SUGGEST WE WILL HAVE A MIX OF SUN AND CLOUDS TODAY
FOLLOWED BY A LITTLE MORE CLEARING TONIGHT. 00Z NUMERICAL GUIDANCE
AND TIME HEIGHT RH X-SECTIONS SUGGEST THE MOST EXTENSIVE CLEARING
SHOULD COME FOR MONDAY. THE EARLY MARCH SUNSHINE WILL HELP TO BOOST
MAX TEMPS INTO THE 30 TO 35 DEGREE RANGE MONDAY... WHICH IS STILL
SEVERAL DEGREES BELOW NORMAL FOR THIS TIME OF YEAR.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 315 AM EST SAT MAR 2 2013
MAIN FOCUS OF THE LONG TERM IS ON THE SHORTWAVE SEEN SPINNING TOWARD
THE BRITISH COLUMBIA COAST IN THE GULF OF ALASKA. THE WAVE PROVIDES
THE ONLY POSSIBILITY OF PRECIPITATION IN THE LONG TERM. THE GFS AND
ECMWF ARE AT ODDS WITH ONE ANOTHER IN THE TRACK OF THE WAVE SO IT IS
FAR FROM CERTAIN AS TO WHETHER IT BRINGS SW LOWER MI ANY PRECIP. THE
GFS DRIVES IT INTO THE HEART OF THE WESTERN RIDGE...WHILE THE ECMWF
SLIDES IT OVER THE TOP OF THE RIDGE A BIT MORE. THE ECMWF SEEMS A
BIT MORE PLAUSIBLE AND RESULTS IN A FARTHER NORTH TRACK. HAVE THROWN
SOME SMALL POPS (20/30 PCT) BACK INTO THE FORECAST DURING THE MONDAY
NIGHT THROUGH TUESDAY NIGHT TIME FRAME. THE ECMWF WOULD EVEN IMPLY
SOME LIGHT ACCUMULATING SNOW TUESDAY NIGHT...A COUPLE INCHES
POTENTIALLY. WILL MONITOR THE TREND HERE...BUT WOULD NOT BE
SURPRISED TO SEE THE GFS DRIFT TOWARD THE ECMWF TRACK/EVOLUTION.
ALSO CAN SEE AN INCREASE IN POPS WITH TIME IF THE TREND HOLDS.
OTHERWISE...RIDGING BUILDS IN BEHIND THE EARLY WEEK SHORTWAVE
RESULTING IN MORE IN THE WAY OF SUNSHINE AND WARMING TEMPS.
TEMPERATURES WILL BE BACK TO AROUND NORMALS MID/LATE WEEK. HIGHS ON
FRIDAY SHOULD PUSH WELL INTO THE 40S...WITH 850MB TEMPS FORECAST TO
BE IN THE +3 TO +5 C RANGE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 118 PM EST SAT MAR 2 2013
IT/S A TRICKY CLOUD FORECAST TODAY. THE WRN TAF SITES MAY SCATTER
OUT THIS AFTERNOON. LATEST VIS LOOP SHOWS THINNING CLOUDS OVER NW
LWR MI. HOWEVER...CLOUDS OVER LAKE MICHIGAN ARE ALSO MOVING SOUTH
AND MAY CLIP KMKG. ADDITIONALLY...MVFR CIGS ELSEWHERE KEEP
BOUNCING BETWEEN 1900-2100 FEET. KLAN/KJXN WILL LIKELY SEE THE
LOWER CIGS WHILE THE WRN TAF SITES WILL LIKELY SEE CIGS GREATER
THAN 2000 FT. KAZO SHOULD BE JUST FAR ENOUGH SOUTHWEST TO SEE
SCATTERED CLOUDS. IF A CIG DEVELOPS THERE IT LIKELY WON/T LAST
LONG.
&&
.MARINE...
ISSUED AT 956 AM EST SAT MAR 2 2013
THE WAVE MODEL SUGGESTS 3 TO 5 FOOT WAVES INTO SUNDAY MORNING NEAR
AND SOUTH OF HOLLAND SO I ISSUED A SMALL CRAFT ADVISORY TO COVER THIS.
I WILL ADMIT THE WEB CAMS DO NOT LOOK ALL THAT IMPRESSIVE BUT THERE
ARE NORTH WINDS AND THIS IS COLD AIR SO I WENT AHEAD WITH THIS ANYWAY.
ALSO IT MATCHES WHAT IWX HAD OUT.
&&
.HYDROLOGY...
ISSUED AT 315 AM EST SAT MAR 2 2013
THERE IS SOME POTENTIAL FOR INCREASING ICE ON THE MUSKEGON RIVER
THROUGH THE WEEKEND. HOWEVER WATER TEMPERATURES ON THE PINE AND
GRAND RIVERS ARE SEVERAL DEGREES ABOVE FREEZING SO ICE SHOULD BE
DECREASING. STRONGER MARCH SUNSHINE THE NEXT FEW DAYS MAY OFFSET ANY
INCREASE IN ICE AT NIGHT.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST SUNDAY FOR LMZ844>846.
&&
$$
UPDATE...WDM
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...DUKE
AVIATION...93
HYDROLOGY...LAURENS
MARINE...WDM
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1245 PM EST SAT MAR 2 2013
.SYNOPSIS...
ISSUED AT 315 AM EST SAT MAR 2 2013
HIGH PRESSURE WILL BRING FAIR AND DRY BUT COLD WEATHER THROUGH THE
WEEKEND. TEMPERATURES WILL UNDERGO A GRADUAL MODERATING TREND FOR
THE UPCOMING WEEK WITH TRANQUIL WEATHER EXPECTED TO CONTINUE.
&&
.UPDATE...
ISSUED AT 956 AM EST SAT MAR 2 2013
I UPDATED THE Z0NES FOR MORE CLOUDINESS INTO SUNDAY. I ALSO ADDED
FLURRIES INTO THIS EVENING. THE LATEST SATELLITE LOOPS SHOW ONLY
THE AREA NEAR AND EAST OF US-131 AND SOUTH OF BIG RAPIDS HAVING
ANY SUNSHINE. ALL OF THE MODELS SHOW THE CLOUDS WILL FILL IN THERE
TOO AS THE THERMAL TROUGH MOVES THROUGH. MOST OF THE REPORTING
STATIONS NORTH AND EAST OF GRR HAVE FLURRIES AND OUR RADAR HAS
SOME WEAK RETURNS EAST OF THE OFFICE WHICH ARE INCREASING AND
MOVING TO THE SOUTH SOUTHWEST. GIVEN THE FLURRIES ALREADY THERE AND
THE RAP MODEL SUGGESTING .03 AT GRR BTW 18Z AND 06Z IT SEEMS
PRUDENT TO PUT AT LEAST A FEW FLURRIES IN THE FORECAST. IF THE
SNOW SHOWER ACTIVITY INCREASES THAN I WILL UPDATE AGAIN.
&&
.SHORT TERM...(TODAY THROUGH MONDAY AFTERNOON)
ISSUED AT 315 AM EST SAT MAR 2 2013
HIGH PRESSURE WILL PRODUCE DRY BUT COLD WX THROUGH MONDAY WITH MAX
TEMPS THIS WEEKEND ONLY REACHING THE UPPER 20S TO LOWER 30S AND MIN
TEMPS MAINLY IN THE TEENS. SOME SINGLE DIGIT MINS ARE POSSIBLE THE
NEXT FEW NIGHTS NORTH OF I-96 GIVEN EXPANSIVE SNOW COVER AND
DEPENDENT LARGELY ON EXTENT OF CLEARING.
CURRENT IR SAT TREND CORROBORATED WITH 00Z NAM/GFS GUIDANCE TIME
HEIGHT RH PROGS SUGGEST WE WILL HAVE A MIX OF SUN AND CLOUDS TODAY
FOLLOWED BY A LITTLE MORE CLEARING TONIGHT. 00Z NUMERICAL GUIDANCE
AND TIME HEIGHT RH X-SECTIONS SUGGEST THE MOST EXTENSIVE CLEARING
SHOULD COME FOR MONDAY. THE EARLY MARCH SUNSHINE WILL HELP TO BOOST
MAX TEMPS INTO THE 30 TO 35 DEGREE RANGE MONDAY... WHICH IS STILL
SEVERAL DEGREES BELOW NORMAL FOR THIS TIME OF YEAR.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 315 AM EST SAT MAR 2 2013
MAIN FOCUS OF THE LONG TERM IS ON THE SHORTWAVE SEEN SPINNING TOWARD
THE BRITISH COLUMBIA COAST IN THE GULF OF ALASKA. THE WAVE PROVIDES
THE ONLY POSSIBILITY OF PRECIPITATION IN THE LONG TERM. THE GFS AND
ECMWF ARE AT ODDS WITH ONE ANOTHER IN THE TRACK OF THE WAVE SO IT IS
FAR FROM CERTAIN AS TO WHETHER IT BRINGS SW LOWER MI ANY PRECIP. THE
GFS DRIVES IT INTO THE HEART OF THE WESTERN RIDGE...WHILE THE ECMWF
SLIDES IT OVER THE TOP OF THE RIDGE A BIT MORE. THE ECMWF SEEMS A
BIT MORE PLAUSIBLE AND RESULTS IN A FARTHER NORTH TRACK. HAVE THROWN
SOME SMALL POPS (20/30 PCT) BACK INTO THE FORECAST DURING THE MONDAY
NIGHT THROUGH TUESDAY NIGHT TIME FRAME. THE ECMWF WOULD EVEN IMPLY
SOME LIGHT ACCUMULATING SNOW TUESDAY NIGHT...A COUPLE INCHES
POTENTIALLY. WILL MONITOR THE TREND HERE...BUT WOULD NOT BE
SURPRISED TO SEE THE GFS DRIFT TOWARD THE ECMWF TRACK/EVOLUTION.
ALSO CAN SEE AN INCREASE IN POPS WITH TIME IF THE TREND HOLDS.
OTHERWISE...RIDGING BUILDS IN BEHIND THE EARLY WEEK SHORTWAVE
RESULTING IN MORE IN THE WAY OF SUNSHINE AND WARMING TEMPS.
TEMPERATURES WILL BE BACK TO AROUND NORMALS MID/LATE WEEK. HIGHS ON
FRIDAY SHOULD PUSH WELL INTO THE 40S...WITH 850MB TEMPS FORECAST TO
BE IN THE +3 TO +5 C RANGE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1241 PM EST SAT MAR 2 2013
LATEST VIS LOOP SHOWS CLOUDS BEGINNING TO SCATTER OUT ACROSS NRN
LWR. WE/RE THINKING THAT WILL OCCUR AT THE TAF SITES TOO LATER
TONIGHT. SCATTERED OUT THE CIGS OVERNIGHT. ERN TAF SITES SHOULD BE
THE LAST TO SCATTER OUT.
&&
.MARINE...
ISSUED AT 956 AM EST SAT MAR 2 2013
THE WAVE MODEL SUGGESTS 3 TO 5 FOOT WAVES INTO SUNDAY MORNING NEAR
AND SOUTH OF HOLLAND SO I ISSUED A SMALL CRAFT ADVISORY TO COVER THIS.
I WILL ADMIT THE WEB CAMS DO NOT LOOK ALL THAT IMPRESSIVE BUT THERE
ARE NORTH WINDS AND THIS IS COLD AIR SO I WENT AHEAD WITH THIS ANYWAY.
ALSO IT MATCHES WHAT IWX HAD OUT.
&&
.HYDROLOGY...
ISSUED AT 315 AM EST SAT MAR 2 2013
THERE IS SOME POTENTIAL FOR INCREASING ICE ON THE MUSKEGON RIVER
THROUGH THE WEEKEND. HOWEVER WATER TEMPERATURES ON THE PINE AND
GRAND RIVERS ARE SEVERAL DEGREES ABOVE FREEZING SO ICE SHOULD BE
DECREASING. STRONGER MARCH SUNSHINE THE NEXT FEW DAYS MAY OFFSET ANY
INCREASE IN ICE AT NIGHT.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST SUNDAY FOR LMZ844>846.
&&
$$
UPDATE...WDM
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...DUKE
AVIATION...93
HYDROLOGY...LAURENS
MARINE...WDM
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1122 AM CST SAT MAR 2 2013
.AVIATION...18Z KGRI TAF. QUIET CONDITIONS ARE EXPECTED THROUGH
THE TAF PERIOD...WITH THE PRIMARY CONCERN LYING WITH FOG POTENTIAL
TONIGHT. THROUGH THE REST OF THIS AFTERNOON...SCT MID LEVEL
CLOUDS WILL LINGER ON...AND WINDS WILL REMAIN S/SWRLY WITH SPEEDS
ARND 10KTS AHEAD OF A FRONTAL BOUNDARY OVER WRN NEB/KS. SOME
MODELS/GUIDANCE SUGGEST THAT WITH THE DIMINISHING WINDS EXPECTED
OVERNIGHT THAT FOG WILL DEVELOP...AND CONTINUED THE MVFR
VISIBILITIES. THERE ARE ENOUGH DIFFERENCES IN THE MODELS TO NOT
GO ANY LOWER THAN THAT AT THIS POINT.
&&
.PREV DISCUSSION... /ISSUED 622 AM CST SAT MAR 2 2013/
SHORT TERM...(TODAY THROUGH MONDAY NIGHT)
ISSUED AT 403 AM CST SAT MAR 2 2013
TODAY...THERE HAS BEEN SOME EARLY MORNING FOG WEST OF HIGHWAY 281
WITH PATCHY DENSE FOG AT TIMES WEST OF HIGHWAY 183. THE HRRR MODEL
LINGERS THIS FOG ALL THE WAY THROUGH THE ENTIRE MORNING AND
EXPANDS THE FOG EASTWARD IN AREA TO INCLUDE THE HIGHWAY 281
CORRIDOR. THE WIND WILL BE LIGHT...WHICH WILL MAKE IT DIFFICULT
FOR THE FOG TO DISPERSE TOO QUICKLY. HOWEVER...GIVEN THE LIMITED
EXTENT OF THE FOG THUS FAR AS OF 4 AM...BELIEVE THAT THE FOG WILL
NOT BE AS BIG OF A DEAL AS INDICATED BY THE HRRR MODEL.
THEREFORE...WILL BE CALLING FOR ANY FOG TO LIFT BY MID MORNING.
THE WIND WILL GRADUALLY INCREASE FROM THE SOUTH THIS AFTERNOON AND
WARMER AIR ALOFT WILL ALSO WORK IN FROM THE WEST AS AN UPPER RIDGE
BEGINS TO SLIDE EAST INTO THE PLAINS. THEREFORE...EXPECT A WARMER
DAY WITH HIGHS A GOOD DEAL ABOVE FREEZING DESPITE THE SNOW COVER.
HIGHS SHOULD RANGE FROM THE MID 30S ALONG HIGHWAY 81 TO THE MID 40S
WEST OF HIGHWAY 183.
SUNDAY...THIS WILL BE THE NICEST DAY OF THE WEEKEND WITH MUCH OF
THE REMAINING SNOW COVER MELTING. THE WIND WILL REMAIN SOUTHERLY
AND 850MB TEMPERATURES WILL CONTINUE TO CLIMB INTO THE 8-12C RANGE
WITH RIDGING ALOFT.
MONDAY INTO MONDAY NIGHT...A POTENT LITTLE STORM SYSTEM IS
PROJECTED TO TRACK ACROSS THE DAKOTAS AND SHOULD SEND A FAIRLY
SHARP SFC COLD FRONT THROUGH NEBRASKA. HOWEVER...MOST OF THE
PRECIPITATION/SNOW WILL BE WELL NORTH OF OUR FORECAST AREA IN
ASSOCIATION WITH THE UPPER LOW AND SHOULD TRACK SOUTHEAST INTO
MINNESOTA AND EASTERN IOWA. THE LATEST RUN OF THE 00Z ECWMF IS
EVEN FURTHER NORTH WITH THIS SYSTEM THAN PREVIOUS RUNS RESULTING
IN DECREASING POPS ACROSS OUR FORECAST AREA. MOST AREAS WILL FAIL
TO SEE MEASURABLE PRECIPITATION IF THIS NORTHERN TRACK HOLDS TRUE.
IT WILL BE BREEZY BEHIND THE COLD FRONT...BUT EXPECT THE STRONGER
WIND MAY NOT MOVE INTO OUR AREA UNTIL THE UPPER LOW PASSES FURTHER
TO OUR EAST...WHICH WOULD BE ON TUESDAY. TEMPERATURES WILL BE
COOLER ON MONDAY BEHIND THE COLD FRONT.
LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 403 AM CST SAT MAR 2 2013
ALTHOUGH THIS 4-DAY PERIOD DOES NOT APPEAR TO CONTAIN ANY TRULY HIGH
IMPACT WEATHER...AND IS OFFICIALLY PRECIP-FREE IN OUR PRODUCTS AT
LEAST FOR NOW...WILL HAVE TO KEEP AN EYE OUT FOR VARIOUS ELEMENTS
INCLUDING THE POSSIBILITY OF SOME LINGERING FLURRIES/LIGHT SNOW
TUESDAY...POTENTIALLY STRONG NORTH WINDS TUESDAY...AND POTENTIALLY
FAIRLY STRONG SOUTH WINDS BY THURSDAY.
STARTING OFF TUESDAY/TUESDAY NIGHT...UNFORTUNATELY MODEL AGREEMENT
AMONGST THE 00Z ECMWF/GFS/GEM SOLUTIONS LEAVES A BIT TO BE DESIRED.
ON A BASIC SYNOPTIC SCALE ALOFT...ALL 3 MODELS AT LEAST SHOW A
FAIRLY STOUT NORTHWEST-FLOW SHORTWAVE TROUGH DIVING SOUTHEAST FROM A
POSITION IN THE THE NORTHERN OR CENTRAL PLAINS TUESDAY MORNING...TO
THE TENNESSEE VICINITY BY WEDNESDAY MORNING. HOWEVER...GETTING MORE
INTO THE DETAILS...THE GFS/GEM TRACKS THE HEART OF THE 500MB VORT
MAX ACROSS AT LEAST EASTERN IF NOT CENTRAL PORTIONS OF NEB/KS DURING
THE DAY...WHILE THE ECMWF KEEPS THE MAIN FORCING A FEW HUNDRED MILES
FARTHER NORTHEAST OVER SOUTHERN MN/IA. CERTAINLY IF THE FARTHER
SOUTHWEST SOLUTIONS ARE CORRECT...WE MAY VERY WELL NEED SOME
FLURRIES OR MAYBE EVEN A MEASURABLE POP FOR LIGHT SNOW INTRODUCED IN
LATER FORECASTS MAINLY ACROSS THE NORTHEAST 1/2 OF THE CWA FOR
TUESDAY DAYTIME. HOWEVER...GIVEN THAT THIS IS STILL 7 PERIODS OUT
WILL HOLD OFF FOR NOW. OF LIKELY GREATER IMPORTANCE...AND WHAT ALL
OF THESE MODELS SEEM TO AGREE ON...IS THAT TUESDAY IS TRENDING
WINDIER AS THIS AFOREMENTIONED SHORTWAVE PASSES AND SURFACE PRESSURE
RISES RAMP UP IN RESPONSE TO STRONG HIGH PRESSURE NOSING IN FROM THE
NORTH. FOR NOW HAVE RAISED SUSTAINED SPEEDS GENERALLY 5-10 MPH FROM
PREVIOUS FORECAST...GETTING UP IN THE 20-25 MPH RANGE BUT STILL
SOLIDLY 5 MPH SHORT OF ADVISORY CRITERIA. THIS WILL BEAR WATCHING
HOWEVER...AND IF THESE SPEEDS PICK UP MUCH MORE A STRONG WIND
MENTION MAY SOON BE WARRANTED IN THE HAZARDOUS WEATHER OUTLOOK. BY
TUESDAY EVENING...WIND SPEEDS SHOULD SUBSIDE FAIRLY STEADILY AS THE
HIGH PRESSURE AXIS SETTLES INTO THE CENTRAL PLAINS. TEMP-WISE...MADE
ONLY SMALL TWEAKS WITH DAYTIME HIGHS SOMEWHERE IN THE 30S AND TUES
NIGHT LOWS MAINLY IN THE TEENS.
WEDNESDAY/WEDNESDAY NIGHT...THE ECMWF/GFS/GEM ARE IN FAIRLY GOOD
AGREEMENT FOR THIS TIME RANGE IN DEPICTING A BRIEF PERIOD OF
SHORTWAVE RIDGING ALOFT TRANSLATING OVER THE CENTRAL PLAINS IN
ADVANCE OF THE NEXT UPSTREAM OPEN WAVE MAKING INROADS ACROSS THE
WESTERN CONUS. THIS GIVES A RATHER HIGH CONFIDENCE IN A DRY 24
HOURS. WITH THE SURFACE RIDGE AXIS QUICKLY MOVING OFF TO THE EAST
AND HIGH PLAINS SURFACE PRESSURE FALLS COMMENCING TO OUR
EAST...WEDNESDAY SHOULD HAVE SOUTH-SOUTHEAST BREEZES AROUND 15 MPH
OR HIGHER...WITH THESE SPEEDS MAINTAINING THROUGH THE NIGHT.
DESPITE THE SOUTHERLY WIND DIRECTION...NOT SURE HOW STRONG WARMING
WILL BE GIVEN THAT COLD AIR WILL BE RE-CIRCULATED AROUND THE
DEPARTING RIDGE AXIS TO SOME EXTENT. AS A RESULT...ACTUALLY NUDGED
DOWN HIGHS A FEW DEGREES ALL AREAS...BUT STILL INTO THE 40S EXCEPT
UPPER 30S FAR NORTHEAST. WEDNESDAY NIGHT LOW TEMPS SHOULD AVERAGE
AROUND 10 DEGREES WARMER THAN TUESDAY NIGHT WITH MAINLY UPPER 20S TO
NEAR 30.
THURSDAY/THURSDAY NIGHT...CONFIDENCE STARTS TO WANE A LITTLE BIT
THAT THIS 24 HOURS WILL TRULY STAY PRECIP-FREE...AS THE
ECMWF/GFS/GEM START TO DIVERGE REGARDING HOW THE WESTERN CONUS
TROUGH IS HANDLED. WHILE THE ECMWF/GFS TRACK A LEAD MID LEVEL
SHORTWAVE MAINLY TO OUR NORTH INTO THE DAKOTAS DURING THIS
TIME...THE GEM SOLUTION TAKES THIS LEAD WAVE RIGHT INTO WESTERN
NEB/KS BY THURS EVENING...SUGGESTING SOME POSSIBLE RAIN SHOWER
POTENTIAL. FOR NOW WILL MAINTAIN THE DRY COURSE. AT THE
SURFACE...SOUTHERLY WINDS WILL LIKELY RAMP UP ANOTHER NOTCH IN A
TIGHTENED PRESSURE GRADIENT...AND ALTHOUGH THE OFFICIAL GRIDS ONLY
DEPICT AROUND 20 MPH SUSTAINED SPEEDS AT THIS TIME...ACTUAL SPEEDS
COULD ULTIMATELY PROVE TO BE AT LEAST 5-10 MPH HIGHER IF TRENDS
HOLD. TEMP-WISE...THURSDAY STILL LOOKS LIKE THE LIKELY CANDIDATE FOR
THE WARMEST DAY OF THE WEEK...ALTHOUGH EVEN THE DEGREE OF WARMING
ABOVE THE SURFACE AT 850MB IS NOT SHOWING GREAT MODEL AGREEMENT.
GIVEN THIS UNCERTAINTY...OPTED TO MAKE NO CHANGES WHATSOEVER TO
PREVIOUS HIGHS...PUSHING THE ENTIRE CWA SOMEWHERE INTO THE
50S...WITH FAR WESTERN COUNTIES MAYBE CRACKING 60. PER THE
ECMWF/GFS...A COLD FRONT THEN STARTS SAGGING SOUTHWARD INTO THE CWA
THURSDAY NIGHT.
FRIDAY...THE GENERAL THEME PER THE ECMWF/GFS IS THAT BROAD SOUTHWEST
FLOW ALOFT PERSISTS OVER THE CENTRAL PLAINS...DOWNSTREAM FROM A
LARGE TROUGH/CLOSED LOW DIGGING INTO THE SOUTHERN CA/AZ REGION.
THERE ARE SUGGESTIONS THAT SOME RAIN SHOWERS COULD BREAK OUT MAINLY
LATE IN THE DAY IN PARTS OF THE CWA PER THE ECMWF...BUT WILL HOLD
POPS IN SILENT TERRITORY FOR NOW...WITH POTENTIALLY MUCH BETTER
PRECIP CHANCES ENTERING THE PICTURE JUST BEYOND THE OFFICIAL
FORECAST PERIODS FOR FRI NIGHT-SATURDAY. HOWEVER...EVEN THIS WEEKEND
PRECIP CHANCE IS IN QUESTION REGARDING WHETHER IT SQUARELY AFFECTS
THE CWA...OR TRENDS MORE TO OUR SOUTH. TEMP-WISE...FRIDAY CERTAINLY
LOOKS COOLER THAN THURSDAY WITH STEADY NORTHEAST WINDS IN PLACE
BEHIND A COLD FRONT...JUST A MATTER OF HOW MUCH COOLER. FOR NOW WILL
RUN WITH A RANGE FROM MID 40S NORTH TO LOW 50S SOUTH...WHICH IS JUST
A TOUCH COOLER THAN PREVIOUS FORECAST.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AVIATION...ADO
SHORT TERM...WESELY
LONG TERM...PFANNKUCH
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
335 PM CST SAT MAR 2 2013
.SHORT TERM...TONIGHT THROUGH TUESDAY
MAIN FORECAST ISSUES ARE RELATED TO TIMING...LOCATION AND PRECIP
AMOUNTS WITH THE APPROACHING WINTER STORM... EXPECTED TO IMPACT THE
AREA FROM LATE SUNDAY THROUGH EARLY TUESDAY.
FOR TONIGHT... PATCHY LIGHT SNOW OR SNOW FLURRIES ARE POSSIBLE
THROUGH EARLY EVENING ACROSS NORTHWEST TO NCNTRL MN WITH VARIABLE
CLOUDS AND LIGHT EAST SOUTHEAST WINDS OVER ERN ND AND THE RED RIVER
VALLEY CORRIDOR.
SUNDAY...CLOUDS SHOULD INCREASE THROUGH THE DAY AS THE NEXT STORM
SYSTEM APPROACHES. WITH LIGTH TO MODERATE SOUTH SOUTHEAST BLAYER
FLOW AND MIXED CLOUDS EARLY... EXPECT TEMPS TO WARM TO NEAR SEASONAL
NORMALS THROUGH THE FA.
SUNDAY NIGHT AND MONDAY...HAVE GENERALLY USED A MODEL BLEND OF THE
12Z NAM...GFS AND ECMWF TO ACHIEVE A COHERENT PICTURE OF SNOWFALL
AMOUNTS AND TIMING ACROSS THE AREA. OVER THE PAST FEW MODEL CYCLES
THE NAM HAS FAVORED HEAVIER AMOUNTS IN THE NORTH VALLEY WHILE THE
GFS HAS FAVORED THE SOUTH VALLEY. A MODEL BLEND PRODUCES WIDESPREAD
6 TO 10 INCH SNOWFALLS ACROSS ALL OF CNTRL AND ERN ND INTO THE RED
RIVER BASIN AND THEN SOUTHEASTWARD CLOSE TO THE I-94 AND HWY 10
CORRIDORS. THE LOW PRESSURE SYSTEM SOMEWHAT RESEMBLES AN ALBERTA
CLIPPER... BUT WITH SLOWER OVERALL SPEED AND ABUNDANT LOW LEVEL
MOISTURE FEED... LOOKS ABLE TO PRODUCE HEAVIER SNOWFALL AMOUNTS.
MONDAY NIGHT AND TUESDAY...STILL SOME LIGHT SNOW AND BLOWING SNOW
POTENTIAL AS SYSTEM EXITS THE AREA. ABSENCE OF TRAILING DENSE AND
COLD AIRMASS REDUCES THE THREAT OF SIGNIFICANT BLOWING AND DRIFTING.
HOWEVER... WILL NEED TO BE WATCHED AS MODELS INDICATE SOEM POTENTIAL
FOR AN OVERALL DEEPER LOW PRESSURE AND SOMEWHAT HIGHER WINDS.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
MEDIUM-RANGE MODELS NOT IN THE BEST OF AGREEMENT NEXT WEEK...BUT
OVERALL SYNOPTIC PATTERN SHOWS NORTHWEST FLOW ALOFT ON WEDNESDAY
TRANSITIONING TO THE SOUTHWEST FOR THURSDAY AS A SHORT-WAVE RIDGE
MOVES ACROSS THE NORTHERN PLAINS. WILL SEE LOW (20 TO 30 PERCENT)
SNOW CHANCES THURSDAY AND EARLY FRIDAY ACROSS THE NORTH AS A
NORTHERN ROCKIES SURFACE LOW MOVES ACROSS THE DAKOTAS. OTHERWISE...
EXPECT MOSTLY DRY CONDITIONS. A SPLIT-FLOW REGIME DEVELOPS FRIDAY/
SATURDAY AND THIS SHOULD KEEP THE PRIMARY STORM TRACK ACROSS THE
SOUTHERN CONUS AS A LARGE LOW DEVELOPS ACROSS THE FOUR CORNERS. NO
BIG SWINGS IN AIR MASSES...SO EXPECT MINIMAL DAY-TO-DAY TEMPERATURE
CHANGES WITH DAYTIME HIGHS IN THE 20S AND LOWER 30S AND NIGHTTIME
LOWS IN THE SINGLE DIGITS TO TEENS ABOVE ZERO.
&&
.AVIATION...
ALL MODELS OVERESTIMATING LOW CLOUDS IN THE BOUNDARY LAYER THIS
AFTERNOON WITH THE LATEST RAP SEEMING TO HAVE THE BEST HANDLE ON
CURRENT CONDITIONS. IT SHOWS A BAND OF MVFR/IFR CEILINGS MOVING
INTO THE VALLEY THIS EVENING AND OVERNIGHT. HOWEVER...CONFIDENCE
IN THIS SCENARIO IS LOW GIVEN CURRENT MODEL PERFORMANCE. WILL
MAINTAIN A VFR PERSISTENCE FORECAST AT THIS TIME...BUT LOWER
CEILINGS MAY NEED TO BE INTRODUCED LATER TONIGHT. SOUTH-SOUTHEAST
WIND WILL PERSIST THROUGH THE NIGHT BETWEEN 5 AND 15 KTS.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...WINTER STORM WATCH FROM SUNDAY EVENING THROUGH LATE MONDAY
NIGHT FOR NDZ006>008-014>016-024-026>030-038-039-049-052>054.
MN...WINTER STORM WATCH FROM SUNDAY EVENING THROUGH LATE MONDAY
NIGHT FOR MNZ001>004-007-008-013>015-022-027>032-040.
&&
$$
GUST/ROGERS/WJB
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1035 AM CST SAT MAR 2 2013
.DISCUSSION...
THROUGH 16Z...SFC HIGH PRESSURE RIDGE EXTENDS SOUTHWARD ACROSS WRN
ONT AND ERN MN INTO CNTRL IA...WITH LOW LOW PRESSURE DIGGING INTO
THE WRN DKTAS. SOUTHERLY WINDS ARE PICKING UP ACROSS ERN ND AND THE
RRV CORRIDOR AND MORING EMP RECOVERY IS WELL UNDERWAY. SAT IMAGERY
SHOWS N/S ORIENTED WARM FRONTAL MID TO UPR LVL CLOUD BAND STRETCHING
ACROSS ERN ND/SD INTO WRN EDGE OF MN. A FEW SITES HAVE REPORTED
BRIEF PERIODS OF VERY LIGHT SNOW OUT OF MAINLY VFR CIGS. RADAR
INDICATES THAT THIS WEAKLY FORCED LIGHT PRECIP BAND IS MAINLY IN THE
COUNTIES STRADDLING THE ND/MN BORDER ATTM...WITH A VERY SLOW EWD
PROGRESSION INDICATED.
REST OF TDY...12Z NAM AND RAP GUIDANCE SHOWING GOOD AGREEMENT WITH
CURRENT WARM FRONTAL BAND AND SHOW LIGHT PRECIP AND MID LVL CLOUDS
PROGRESSING ACROSS THE RRV THROUGH MIDDAY AND SLOLY EDGING EWD ACROSS
NW MN DURING THE AFTERNOON. SOME MID LVL DRYING IS CURRENTLY EVIDENT
ACROSS CNTRL ND WHICH IS NOT WELL DEPICTED IN MODEL GUIDANCE. WILL
UPDATE FCST GRIDS TO SHOW SOME RECUCTION IN CLOUDS /PATCHY SUNSHINE/
OVER ERN ND THROUGH EARLY AFTERNOON. CLOUDS SHOULD INCREASE AGAIN
THROUUGH LATE AFTERNOON... AHEAD OF THE APPROACHING STORM SYSTEM.
TONIGHT INTO SUNDAY...12Z NAM CONTINUES TO BE THE MORE NORTHERN SOLN
FOR THE TRACK OF OUR NEXT STORM SYSTEM. WILL ADDRESS ANY ADJUSTMENTS
TO FORECAST TRACK...INTENSITY AND PRECIP AMOUNTS WITH AFTERNOON
PACKAGE. OTHERWISE...EXPECT CLDS TO THICKEN IN OVER THE AREA AND
WINDS BECOME VARIABLE OUT OF THE EAST SOUTHEAST AS AREA RESPONDS TO
DEEPENING LOW PRESSURE IN EASTERN MT AND WRN ND.
&&
.AVIATION...
FOG ACROSS THE AREA THIS MORNING HAS DISSIPATED...BUT STILL MAY SEE
SOME REDUCTION IN VISIBILITY DUE TO BR/HZ IN THE 4 TO 6 SM RANGE
ALONG THE VALLEY FLOOR. SOME MID CLOUDS AND BRIEF MVFR CEILINGS MAY
SPREAD INTO THE VALLEY WITH WARM FRONT AND SOME PATCHY LIGHT SNOW
THIS AFTERNOON. SOUTHEAST TO SOUTH WINDS WILL INCREASE TO NEAR 15 KTS
IN THE VALLEY MIDDAY-AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 343 AM CST SAT MAR 2 2013/
SUNDAY WILL SEE WINDS INCREASE FROM THE SOUTHEAST AHD OF NEXT
SYSTEM. EARLY THIS SATURDAY MORNING WATER VAPOR SHOWS A STRONG PLUME
OF MOISTURE FROM THE TROPICS NORTH INTO WCNTRL BRITISH COLUMBIA.
MAIN SHORT WAVE SEEN OFF SHORE OF CNTRL B.C. COAST AND IT IS THIS
SHORT WAVE WHICH MODELS CONTINUE TO HAVE ISSUES WITH IN HOW MUCH TO
DIG IT SOUTH OR KEEP IT FARTHER NORTH. 00Z EURO CAME IN SLOWER AND
FARTHER NORTH THAN PREV RUN AND ALMOST A COMPROMISE BTWN
NAM/GFS/GEM. USING 00Z EURO WOULD HAVE SFC AND UPR LOW IN SRN
ALBERTA 18Z SUN AND THEM MOVING EAST-SOUTHEAST INTO WRN ND 06Z MON
THEN MOVING SFC-UPR LOW INTO EITHER NE SD OR SE ND REGION 18Z MON.
USING THIS CONSENSUS MODEL APPROACH WOULD BRING SIGNIFCANT SNOWS
FARTHER NORTH INTO MOST OF ERN ND AND PARTS OF WCNTRL MN. PER COORD
WITH OTHER OFFICES AND CONSIDERING WE HAVE HAD TWO SPECIAL WEATHER
STATEMENTS FOR THIS EVENT ON FRIDAY FEEL LIKE THE NEXT STEP IS WATCH
PHASE. SO ISSUED A WINTER STORM WATCH FOR SUN NIGHT-MON NIGHT FOR
ALL OF ERN ND INTO WCNTRL MN....GENERALLY WEST OF A
HALLOCK-FOSSTON-WADENA LINE. STILL A LOT COULD CHANGE...BUT THAT
AREA ABOVE IS AT LEAST 50 PCT CONFIDENCE RANGE OF GETTING WARNING
CONDITIONS. WINDS DONT APPEAR STRONG WITH THIS SYSTEM AND SNOWFALL
SPREAD OUT OVER A 18-24 PD BUT CERTAINLY 6+ INCH AMOUNTS APPEAR
LIKELY.
.LONG TERM...TUESDAY THROUGH FRIDAY
LONG RANGE PERIOD STARTS WITH SYSTEM MOVING OUT OF THE FA. EXPECT
LIGHT SNOW TO LINGER ACROSS EASTERN ZONES. MODELS SUGGEST A TROUGH
ASSOCIATED WITH DEPARTING UPPER LOW. AS HAS BEEN THE CASE RECENTLY
VARIED SOLUTIONS EXIST...YET ECMWF/GEM/DGEX SHOWING MOISTURE AND
ISENTROPIC UPGLIDE SUFFICIENT TO WARRANT POPS. HIGH BUILDS IN DRYING
THE COLUMN AND DECREASING WINDS. LOWERED TEMPERATURES A BIT
WEDNESDAY MORNING AS SURFACE RIDGE FORECAST TO LAY ALONG AND EAST OF
CWFA.
RETURN FLOW QUICKLY SETS IN AFTER 00Z THURSDAY...WITH LOW LEVEL WAA
HOLDING STEADY INTO EVENING. MODELS CONTINUE TO OFFER A VARIETY OF
SOLUTIONS FOR LATER IN THE WEEK. GENERAL CONSENSUS IS FOR
PRECIPITATION TO AGAIN BREAK OUT THURSDAY WITH SOUTHWEST FLOW ALOFT.
SURFACE TROUGH / LOW OVER FA...INCREASING MOISTURE AND LIFT ARGUE
FOR THE 20 TO 30 POPS DEPICTED BY BLENDS. WARMING COLUMN COULD
RESULT IN -RA MIX CLOSER TO THE BOUNDARY OVER SOUTHERN FA. YET WITH
HIGH LEVEL OF UNCERTAINTY KEPT PRECIP ALL -SN FOR NOW.
LINGERING -SN POSSIBLE INTO FRIDAY AS UPPER SHORT WAVE MOVES ACROSS
NORTHEAST CWFA.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...WINTER STORM WATCH FROM SUNDAY EVENING THROUGH LATE MONDAY
NIGHT FOR NDZ006>008-014>016-024-026>030-038-039-049-052>054.
MN...WINTER STORM WATCH FROM SUNDAY EVENING THROUGH LATE MONDAY
NIGHT FOR MNZ001>003-027-029>031-040.
&&
$$
GUST/ROGERS/WJB
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1251 PM EST SAT MAR 2 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL CROSS THE REGION FROM THE WEST
REACHING THE THE EAST COAST LATE SUNDAY. HIGH PRESSURE WILL BRIEFLY
MOVE INTO THE AREA ON MONDAY AHEAD OF A LOW PRESSURE SYSTEM THAT
WILL DEVELOP OVER THE MID MISSISSIPPI RIVER VALLEY. THIS LOW IS
EXPECTED TO QUICKLY CROSS THE AREA ON WEDNESDAY WITH COLD HIGH
PRESSURE FILLING IN BEHIND IT ON THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1115 AM...THE AXIS OF THE MID-UPR VORT LOBE IS JUST ABOUT TO
EXIT THE SE CORNER OF THE CWFA. A NICE LITTLE SNOW BAND CONSOLIDATED
FROM THE LAURENS AREA...ENE THRU ROCK HILL AND INTO MONROE NC. THERE
HAVE BEEN A FEW REPORTS OF UP TO 1.5" OF SNOW ACCUM WITH THE BAND.
BUT ROADS SEEM TO BE STAYING WET. THE BAND LOOKS TO BE PICKING UP
SOME SPEED...AS IT SHIFTS TO THE SE...AND MAY BE LOSING SOME
INTENSITY. SO NOT EXPECTING ANY MAJOR IMPACTS WITH IT FOR THE REST
OF ITS TRACK THRU THE REMAINDER OF THE CWFA.
IN THE WAKE OF THE VORT LOBE...CLEARING HAS BEEN OCCURRING ACRS MUCH
OF THE BLUE RIDGE ESCARPMENT AND ADJACENT FOOTHILLS FROM NE GA UP
THRU WRN NC. THE INSOLATION IS QUICKLY DESTABILIZING THE BL...WITH
LAPS ALREADY SHOWING 100-150 J/KG OF CAPE AT 16Z. THE LTST RAP SEEMS
TO BE INITIALIZING BOTH THE QPF AND THE INSTBY THE BEST...AND IT
DOES HAVE UP TO 200-300 J/KG OF CAPE THIS AFTN ACRS THE PIEDMONT
WITH ENUF CONVERGENCE FOR SHWR DEVELOPMENT. THE MAIN LIMITING FACTOR
APPEARS TO BE THE MID AND UPR SUPPORT WILL BE LACKING. EVEN THE
NAM...WHICH INITIALIZES ANOTHER VORT MAX OVR ERN TN...DOES NOT
TRANSLATE THAT FEATURE INTO APPRECIABLE QG FORCING ACRS THE CWFA
THIS AFTN. SO I TRIMMED POPS BACK SLIGHTLY IN THE WEST...BUT OPTED
TO KEEP A HIGH-END CHC TO LIKELY POP IN THE EAST LATER FOR NOW (DUE
TO THE INSTBY AND HI-RES MODELS DEPICTING CONVECTION). THE UPSHOT IS
THAT THE WINTER WX ADV FOR THE SRN NC MTNS/NE GA AND SC MTNS CAN BE
CANCELLED. THE REST OF THE ADV LOOKS GOOD THRU 6 PM...GIVEN THE
CONVECTIVE TRENDS ON THE MRX RADAR.
TONIGHT...NWFS WILL GRADUALLY FADE ALONG THE TN BORDER THIS
EVENING...ENDING DURING THE LATE NIGHT HOURS. WINDS WILL REMAIN FROM
THE NW...RANGING FROM 5 TO 10 KTS. CLOUD COVER WILL DECREASE THROUGH
THE NIGHT...ESPECIALLY EAST OF THE MTNS. LOW TEMPERATURES SHOULD
RANGE FROM THE L20S ACROSS THE MTNS TO THE MID TO U20S EAST.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM SATURDAY...ONE FINAL SHORTWAVE WILL DROP INTO THE EAST
COAST TROUGH AXIS ON SUNDAY BEFORE IT DEPARTS...BRINGING MAINLY
CHANNELED VORTICITY FROM THE WRN GREAT LAKES TO THE WRN CAROLINAS.
DEEP LAYER MOISTURE WILL BE ABSENT WITH THIS FEATURE...BUT LINGERING
LOW LEVEL NW UPSLOPE FLOW MOISTURE MAY PERMIT ISOLATED SNOW SHOWERS
TO LINGER ALONG THE TN BORDER INTO THE MORNING HOURS BEFORE DRYING
UP. CHILLY THICKNESSES...AND LINGERING PATCHY MID AND HIGH
CLOUDS...WILL KEEP TEMPERATURES SEVERAL CATEGORIES BELOW NORMAL.
A FLAT UPPER RIDGE WILL CROSS THE AREA MONDAY THROUGH MONDAY NIGHT.
PLENTY OF HIGH LEVEL CLOUDS SHOULD TOP THE RIDGE AXIS IN THE SWIFT
WESTERLY FLOW ALOFT DURING THIS PERIOD. THE AIRMASS SHOULD MODIFY
ENOUGH TO PUSH MAX TEMPERATURES BACK INTO THE 50S THROUGHOUT MON
AFTN...EXCEPT 40S ALONG THE HIGHER MOUNTAINS.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
AS OF 310 AM SATURDAY...THERE IS GENERALLY GOOD CONSENSUS AMONG THE
VARIOUS MODELS ON A DEEPENING LOW PRES SYSTEM MOVING SE THROUGH THE
MIDWEST ON TUE...CROSSING THE FORECAST AREA ON WED...THEN DEEPENING
FURTHER ALONG THE IMMEDIATE E COAST WED NIGHT. HOWEVER...DIFFERENCES
AMONG THE MODELS IN THE SFC LOW AND 850 MB LOW CENTER TRACKS WILL
PLAY A CRITICAL ROLE IN PRECIPITATION TYPE AND AMOUNT. THERE IS GOOD
AGREEMENT THAT ISENTROPIC LIFT AHEAD OF THE SYSTEM WILL RETURN TO
THE REGION LATE MON NIGHT...WITH THE BEST BELT OF UPGLIDE ACROSS THE
HEART OF THE AREA MIDDAY TUE. PROFILES SUPPORT MAINLY RAIN ON THE
WARM ADVECTION SIDE OF THE SYSTEM...BUT WITH FREEZING RAIN POSSIBLE
IN SPOTS AT ONSET...ESPECIALLY ACROSS THE NRN NC MOUNTAINS.
THICKNESSES SHOULD CRASH WED MORNING AS THE COLD LOW PRESSURE SYSTEM
TRANSITIONS TOWARD THE COAST. QG FORCING SHOULD BE PLENTIFUL JUST
AHEAD OF THE LOW TUE NIGHT AND WED MORNING...WITH SOME DEGREE OF
FRONTOGENESIS AND DEFORMATION ZONE FORCING TRAILING THE DEPARTING
LOW THROUGH THE PIEDMONT WED AFTN/EVENING. VERY STEEP LAPSE RATES
UNDER THE PASSING UPPER LOW SHOULD SUPPORT AT LEAST ISOLD TO SCT
THUNDERSTORMS/THUNDERSNOW AT TIMES. CONFIDENCE IS HIGHEST ON
SIGNIFICANT ACCUMULATING SNOW OVER THE MTNS AND ALSO NC FOOTHILL AND
PIEDMONT LOCATIONS ALONG AND NORTH OF INTERSTATE 40. MORE OF A
RAIN/SNOW MIX IS EXPECTED TOWARD THE INTERSTATE 85 CORRIDOR AND
POINTS SOUTH...BUT LIKELY ENDING AS SNOW SHOWERS. WILL CONTINUE THE
HWO MENTION FOR THIS POTENTIALLY SIGNIFICANT WINTER STORM SYSTEM.
A WARMER AND DRY RIDGE PATTERN WILL RETURN THU THROUGH FRI...WITH
TEMPERATURES SLOWLY REBOUNDING TO WITHIN 5 DEGREES OF NORMAL.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AT KCLT...THE BAND OF SNOW AND ASSOCIATED RESTRICTIONS HAS PUSHED
OFF TO THE SE...ALLOWING KCLT TO GO TO VFR BEFORE THE 18Z TAF
ISSUANCE. THERE IS STILL SOME LOW CLOUDS ACRS THE REGION PER
METARS...SO I WILL KEEP AN HOUR TEMPO FOR MVFR CIGS. OTHERWISE...THE
MAIN CONCERN WILL BE ANOTHER ROUND OF PRECIP THIS AFTN IN THE FORM
OF SCATTERED TO NUMEROUS SHOWERS. MOST OF THE ACTIVITY SHUD REMAIN
LIGHT RAIN...BUT THE HEAVIEST SHOWERS COULD PRODUCE SNOW/GRAUPEL
MIX. CONFIDENCE ON ONE OF THOSE HITTING THE TERMINAL IS TOO LOW TO
MENTION IN THE TAF AT THIS TIME. SO OVERALL EXPECTING VFR THRU THE
PERIOD. WINDS WILL INCREASE OUT OF THE NW...BUT REMAIN UNDER 10 KTS.
ELSEWHERE...SHOWERS ARE BLOSSOMING ON THE RADAR ACRS THE FOOTHILLS
AT TIME OF 18Z TAF ISSUANCE...AND SOME OF THIS ACTIVITY HAS BEEN
REPORTED TO BE PRODUCING GRAUPEL. THE COVERAGE DOES SEEM TO WARRANT
A MENTION OF SHRA AT ALL SITES (EXCEPT KAVL). MOST OF THE ACTIVITY
IS STILL LIGHT...SO CONFIDENCE ON RESTRICTIONS IS TOO LOW TO ADD
MENTION ATTM. SO OVERALL...EXPECTING VFR CONDITIONS THRU THE PERIOD.
MEANWHILE...NW FLOW SNOW SHOWER ACTIVITY WILL CONTINUE ALONG THE
TN/NC BORDER. NOT EXPECTING THIS TO AFFECT KAVL...BUT THERE IS A
POSSIBILITY OF BRIEF CIG AND/OR VSBY RESTRICTIONS THIS AFTN OR EVE.
OUTLOOK...SNOW SHOWERS WILL DIMINSIHING THE TENNESSEE BORDER ON
SUNDAY. MONDAY SHOULD REMAIN VFR ACROSS THE FORECAST AREA.
ANOTHER LOW PRESSURE SYSTEM WILL SPREAD LLVL MOISTURE AND
PRECIPITATION ACROSS THE REGION TUESDAY AND WEDNESDAY MORNING.
CONFIDENCE TABLE...
18-24Z 00-06Z 06-12Z 12-18Z
KCLT HIGH 88% HIGH 100% HIGH 100% HIGH 100%
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAVL HIGH 87% HIGH 100% HIGH 100% HIGH 94%
KHKY HIGH 97% HIGH 100% HIGH 100% HIGH 100%
KGMU HIGH 92% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 94% HIGH 100% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ033-
048>052-058-059.
SC...NONE.
&&
$$
SYNOPSIS...HG
NEAR TERM...ARK/NED
SHORT TERM...HG
LONG TERM...HG
AVIATION...ARK
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1145 AM EST SAT MAR 2 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL CROSS THE REGION FROM THE WEST
REACHING THE THE EAST COAST LATE SUNDAY. HIGH PRESSURE WILL BRIEFLY
MOVE INTO THE AREA ON MONDAY AHEAD OF A LOW PRESSURE SYSTEM THAT
WILL DEVELOP OVER THE MID MISSISSIPPI RIVER VALLEY. THIS LOW IS
EXPECTED TO QUICKLY CROSS THE AREA ON WEDNESDAY WITH COLD HIGH
PRESSURE FILLING IN BEHIND IT ON THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1115 AM...THE AXIS OF THE MID-UPR VORT LOBE IS JUST ABOUT TO
EXIT THE SE CORNER OF THE CWFA. A NICE LITTLE SNOW BAND CONSOLIDATED
FROM THE LAURENS AREA...ENE THRU ROCK HILL AND INTO MONROE NC. THERE
HAVE BEEN A FEW REPORTS OF UP TO 1.5" OF SNOW ACCUM WITH THE BAND.
BUT ROADS SEEM TO BE STAYING WET. THE BAND LOOKS TO BE PICKING UP
SOME SPEED...AS IT SHIFTS TO THE SE...AND MAY BE LOSING SOME
INTENSITY. SO NOT EXPECTING ANY MAJOR IMPACTS WITH IT FOR THE REST
OF ITS TRACK THRU THE REMAINDER OF THE CWFA.
IN THE WAKE OF THE VORT LOBE...CLEARING HAS BEEN OCCURRING ACRS MUCH
OF THE BLUE RIDGE ESCARPMENT AND ADJACENT FOOTHILLS FROM NE GA UP
THRU WRN NC. THE INSOLATION IS QUICKLY DESTABILIZING THE BL...WITH
LAPS ALREADY SHOWING 100-150 J/KG OF CAPE AT 16Z. THE LTST RAP SEEMS
TO BE INITIALIZING BOTH THE QPF AND THE INSTBY THE BEST...AND IT
DOES HAVE UP TO 200-300 J/KG OF CAPE THIS AFTN ACRS THE PIEDMONT
WITH ENUF CONVERGENCE FOR SHWR DEVELOPMENT. THE MAIN LIMITING FACTOR
APPEARS TO BE THE MID AND UPR SUPPORT WILL BE LACKING. EVEN THE
NAM...WHICH INITIALIZES ANOTHER VORT MAX OVR ERN TN...DOES NOT
TRANSLATE THAT FEATURE INTO APPRECIABLE QG FORCING ACRS THE CWFA
THIS AFTN. SO I TRIMMED POPS BACK SLIGHTLY IN THE WEST...BUT OPTED
TO KEEP A HIGH-END CHC TO LIKELY POP IN THE EAST LATER FOR NOW (DUE
TO THE INSTBY AND HI-RES MODELS DEPICTING CONVECTION). THE UPSHOT IS
THAT THE WINTER WX ADV FOR THE SRN NC MTNS/NE GA AND SC MTNS CAN BE
CANCELLED. THE REST OF THE ADV LOOKS GOOD THRU 6 PM...GIVEN THE
CONVECTIVE TRENDS ON THE MRX RADAR.
TONIGHT...NWFS WILL GRADUALLY FADE ALONG THE TN BORDER THIS
EVENING...ENDING DURING THE LATE NIGHT HOURS. WINDS WILL REMAIN FROM
THE NW...RANGING FROM 5 TO 10 KTS. CLOUD COVER WILL DECREASE THROUGH
THE NIGHT...ESPECIALLY EAST OF THE MTNS. LOW TEMPERATURES SHOULD
RANGE FROM THE L20S ACROSS THE MTNS TO THE MID TO U20S EAST.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM SATURDAY...ONE FINAL SHORTWAVE WILL DROP INTO THE EAST
COAST TROUGH AXIS ON SUNDAY BEFORE IT DEPARTS...BRINGING MAINLY
CHANNELED VORTICITY FROM THE WRN GREAT LAKES TO THE WRN CAROLINAS.
DEEP LAYER MOISTURE WILL BE ABSENT WITH THIS FEATURE...BUT LINGERING
LOW LEVEL NW UPSLOPE FLOW MOISTURE MAY PERMIT ISOLATED SNOW SHOWERS
TO LINGER ALONG THE TN BORDER INTO THE MORNING HOURS BEFORE DRYING
UP. CHILLY THICKNESSES...AND LINGERING PATCHY MID AND HIGH
CLOUDS...WILL KEEP TEMPERATURES SEVERAL CATEGORIES BELOW NORMAL.
A FLAT UPPER RIDGE WILL CROSS THE AREA MONDAY THROUGH MONDAY NIGHT.
PLENTY OF HIGH LEVEL CLOUDS SHOULD TOP THE RIDGE AXIS IN THE SWIFT
WESTERLY FLOW ALOFT DURING THIS PERIOD. THE AIRMASS SHOULD MODIFY
ENOUGH TO PUSH MAX TEMPERATURES BACK INTO THE 50S THROUGHOUT MON
AFTN...EXCEPT 40S ALONG THE HIGHER MOUNTAINS.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 310 AM SATURDAY...THERE IS GENERALLY GOOD CONSENSUS AMONG THE
VARIOUS MODELS ON A DEEPENING LOW PRES SYSTEM MOVING SE THROUGH THE
MIDWEST ON TUE...CROSSING THE FORECAST AREA ON WED...THEN DEEPENING
FURTHER ALONG THE IMMEDIATE E COAST WED NIGHT. HOWEVER...DIFFERENCES
AMONG THE MODELS IN THE SFC LOW AND 850 MB LOW CENTER TRACKS WILL
PLAY A CRITICAL ROLE IN PRECIPITATION TYPE AND AMOUNT. THERE IS GOOD
AGREEMENT THAT ISENTROPIC LIFT AHEAD OF THE SYSTEM WILL RETURN TO
THE REGION LATE MON NIGHT...WITH THE BEST BELT OF UPGLIDE ACROSS THE
HEART OF THE AREA MIDDAY TUE. PROFILES SUPPORT MAINLY RAIN ON THE
WARM ADVECTION SIDE OF THE SYSTEM...BUT WITH FREEZING RAIN POSSIBLE
IN SPOTS AT ONSET...ESPECIALLY ACROSS THE NRN NC MOUNTAINS.
THICKNESSES SHOULD CRASH WED MORNING AS THE COLD LOW PRESSURE SYSTEM
TRANSITIONS TOWARD THE COAST. QG FORCING SHOULD BE PLENTIFUL JUST
AHEAD OF THE LOW TUE NIGHT AND WED MORNING...WITH SOME DEGREE OF
FRONTOGENESIS AND DEFORMATION ZONE FORCING TRAILING THE DEPARTING
LOW THROUGH THE PIEDMONT WED AFTN/EVENING. VERY STEEP LAPSE RATES
UNDER THE PASSING UPPER LOW SHOULD SUPPORT AT LEAST ISOLD TO SCT
THUNDERSTORMS/THUNDERSNOW AT TIMES. CONFIDENCE IS HIGHEST ON
SIGNIFICANT ACCUMULATING SNOW OVER THE MTNS AND ALSO NC FOOTHILL AND
PIEDMONT LOCATIONS ALONG AND NORTH OF INTERSTATE 40. MORE OF A
RAIN/SNOW MIX IS EXPECTED TOWARD THE INTERSTATE 85 CORRIDOR AND
POINTS SOUTH...BUT LIKELY ENDING AS SNOW SHOWERS. WILL CONTINUE THE
HWO MENTION FOR THIS POTENTIALLY SIGNIFICANT WINTER STORM SYSTEM.
A WARMER AND DRY RIDGE PATTERN WILL RETURN THU THROUGH FRI...WITH
TEMPERATURES SLOWLY REBOUNDING TO WITHIN 5 DEGREES OF NORMAL.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AT KCLT...THE 12Z TAF WILL BEGIN WITH VFR CONDITIONS AND A LIGHT NE
WIND. CEILING BASES SHOULD GRADUALLY LOWER THROUGH MID MORNING AS
SYNOPTIC SCALE FORCING SPREADS ACROSS THE PIEDMONT. BETWEEN 12Z TO
18Z...MID LEVEL FORCING SHOULD PEAK ACROSS THE TERMINAL...THEN
WEAKEN THROUGH THE AFTERNOON HOURS. NAM FORECAST SOUNDINGS SUPPORTS
CEILINGS FALLING TO LVFR BETWEEN 12Z TO 15Z. THE ARRIVAL OF THE DEEP
FORCING AT DAY BREAK MAY YIELD ONE OF THE HIGHEST CHCS FOR PRECIP
DURING THE PERIOD. ANOTHER BAND OF RASN MAY PASS ACROSS THE TERMINAL
BETWEEN 22Z TO 24Z WITH THE PUSH OF THE DRY SLOT. ONCE THE DRY SLOT
ARRIVES...CEILINGS WILL LIFT AND STEADY NW WINDS SHOULD REMAIN
THROUGH 12Z SUN. I WOULD EXPECT THAT ACCUMULATING SNOW IS POSSIBLE
THIS MORNING AND AGAIN LATE THIS AFTERNOON...ACCUMS WILL LIKELY
REMAIN LESS THAN A HALF INCH.
ELSEWHERE...TIMING SIMILAR TO CLT. HOWEVER...KGSP...KGMU...AND KHKY
SHOULD SEE WINDOWS OF MVFR CEILINGS DEVELOP BETWEEN 12 TO 15Z...BUT
DOWNSLOPE FLOW SHOULD SUPPORT VFR BY MID MORNING. ALL AREAS WILL SEE
THE POTENTIAL FOR LIGHT ACCUMULATING SNOW THIS MORNING....BEST CHC
BETWEEN 12Z TO 16Z. HOWEVER...THE FORMATION OF A WEAKLY CONVECTIVE
BAND THIS AFTERNOON WILL NEED CLOSE ATTENTION.
OUTLOOK...SNOW SHOWERS WILL DIMINSIHING THE TENNESSEE BORDER ON
SUNDAY. MONDAY SHOULD REMAIN VFR ACROSS THE FORECAST AREA.
ANOTHER LOW PRESSURE SYSTEM WILL SPREAD LLVL MOISTURE AND
PRECIPITATION ACROSS THE REGION TUESDAY AND WEDNESDAY MORNING.
CONFIDENCE TABLE...
16-22Z 22-04Z 04-10Z 10-16Z
KCLT HIGH 84% HIGH 100% HIGH 100% HIGH 100%
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAVL HIGH 90% HIGH 100% HIGH 100% HIGH 100%
KHKY HIGH 90% HIGH 100% HIGH 100% HIGH 100%
KGMU HIGH 91% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 89% HIGH 100% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ033-
048>052-058-059.
SC...NONE.
&&
$$
SYNOPSIS...HG
NEAR TERM...ARK/NED
SHORT TERM...HG
LONG TERM...HG
AVIATION...NED
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1105 AM CST SAT MAR 2 2013
.DISCUSSION...
OVERALL...FORECAST IN GOOD SHAPE THIS MORNING. STRATUS ACROSS THE
JAMES RIVER VALLEY PRODUCING A FEW FLURRIES...BUT DRY SUB CLOUD
LAYER ABSORBING PRECIPITATION BEFORE IT REACHES THE SURFACE. GOING
FORECAST HIGHS LOOK REASONABLE...BUT HAVE RAISED FORECAST HIGHS A
FEW DEGREES ACROSS CENTRAL SOUTH DAKOTA WITH APPROACHING WARM FRONT.
&&
.AVIATION.../FOR THE 18Z TAF ISSUANCE/
VFR CONDITIONS ARE EXPECTED THROUGHOUT THE DAYLIGHT HOURS WITH
SOUTHERLY WINDS AROUND 10 KNOTS. MODELS DEPICT LOW LEVEL SATURATION
INCREASING ACROSS THE REGION THIS EVENING IN ADVANCE OF NEXT WAVE TO
IMPACT THE REGION ON SUNDAY. WILL LIKELY BE DIFFICULT TO SCOUR OUT
LOW LEVEL CLOUD ON SUNDAY WITH INCREASING EASTERLY FLOW.
&&
.PREV DISCUSSION.../ISSUED AT 400 AM CST/
NEAR TERM CHALLENGE IS THE LAST REMNANTS OF SOME STRATUS NOSING UP
INTO PARTS OF NORTHWEST IA...ALONG AND JUST EAST OF THE BIG SIOUX
RIVER AT THIS TIME. SITUATED NEAR 925MB...IT IS SLOWLY EDGING
SOUTHWARD AND SHOULD CONTINUE TO PROCEED IN THAT DIRECTION THROUGH
15Z THIS MORNING. AT THAT TIME...BOTH THE NAM12 AND RAP ARE IN GOOD
AGREEMENT IN SHIFTING THE 925MB WINDS FROM THE NORTH/NORTHWEST TO
THE SOUTH BETWEEN 15Z AND 18Z. THEREFORE IF ANY STRATUS IS STILL IN
OUR FAR SOUTHEAST ZONES AT 15Z...IT MAY HAVE TROUBLE LEAVING THAT
AREA UNLESS IT MIXES OUT SOME. OTHERWISE...MID AND HIGH LEVEL CLOUDS
WILL INCREASE TODAY GIVING A PARTLY SUNNY TO MOSTLY CLOUDY SKY
OVERALL. SURFACE RIDGING IS MOVING EASTWARD AT THIS TIME ACROSS OUR
FORECAST AREA WHICH WILL SHIFT THE SURFACE WINDS TO THE SOUTH. GIVEN
THE NAM AND GFS 925MB TEMPERATURES...ANOTHER SEASONALLY COOL DAY
WILL BE IN STORE FOR AREAS ALONG AND EAST OF I 29. HOWEVER OUR
CENTRAL SD ZONES SHOULD WARM INTO THE LOWER AND MID 40S.
NO CHANGES REALLY NEEDED FOR THE TONIGHT PERIOD...WITH A SOUTHEAST
BREEZE STAYING BRISK. THEREFORE NOT ANTICIPATING TEMPERATURES
FALLING OFF ALL THAT MUCH. DUE TO THE BREEZE...WE MAY BE A BIT TOO
COOL WITH THE LOWS TONIGHT SO THAT IS SOMETHING TO WATCH FOR.
ON SUNDAY...WELL ADVERTISED UPPER WAVE BEGINS TO MOVE INTO THE IDAHO
AND WESTERN MT REGION. AHEAD OF IT...SURFACE LOW PRESSURE FORMS IN A
NORTH TO SOUTH ELONGATION ALONG THE FRONT RANGE OF THE ROCKIES. THE
NORTHERN PORTION OF THE LOW THEN EXTENDS A DECENT WARM FRONT
SOUTHEASTWARD INTO THE CENTRAL PLAINS. TO THE NORTH OF THE WARM
FRONT...INDICATIONS ARE INCREASING THAT THERE MAY BE ENOUGH
SATURATION AND ISENTROPIC LIFT TO PRODUCE SOME LIGHT
PRECIPITATION...WITH THE TYPE DEPENDING ON SURFACE TO 850MB
TEMPERATURES. THE MOST CONCERN AT THIS TIME IS IN AN AREA FROM
EASTERN KINGSBURY AND WESTERN BROOKINGS COUNTIES...WHERE THERE COULD
BE SOME LIGHT FREEZING RAIN. RIGHT NOW...HAVE VERY MINIMAL
ACCUMULATIONS OF ICE IN THOSE AREAS BECAUSE SURFACE TEMPERATURES
SHOULD WARM INTO THE LOWER 30S DURING THE AFTERNOON. BUT WILL LIKELY
MENTION THIS POSSIBILITY IN THE FORTH COMING HWO. CLOSER TO THE WARM
FRONT...TEMPERATURES WILL BE QUITE MILD IN OUR CENTRAL SD ZONES...
WITH 40S WIDESPREAD IN THOSE AREAS. CONVERSELY IN OUR NORTHEAST
ZONES...LOWER 30S IS LIKELY ALL THE WARMING THEY WILL GET.
FOR THE REST OF THE FORECAST SUNDAY NIGHT THROUGH MONDAY NIGHT...
FOLLOWED A BLEND OF THE 00Z GFS/00Z GEM GLOBAL AND 12Z ECMWF. THE
NAM LOOKS TO BE A NORTHERN OUTLIER AT THIS TIME AS IT SO OFTEN IS
WITH SYSTEMS IN THE NORTHERN JET STREAM MOVING OUT OF THE NORTHERN
ROCKIES. THAT SAID...THE 00Z ECMWF DID ALSO TREND A BIT FURTHER
NORTHWARD WITH THE STORM TRACK COMPARED WITH ITS 12Z COUNTERPART.
HAVE NOTICED THE LAST COUPLE OF DAYS THAT THE ECMWF IS BATTLING
ITSELF WITH THE 00Z RUNS FURTHER NORTH THEN THE 12Z RUNS WHICH IS
INTERESTING.
ON SUNDAY NIGHT...MOST OF THE PRECIPITATION WILL STILL LIKELY LIE
NEAR THE 850MB BAROCLINIC ZONE CLOSE TO THE AFOREMENTIONED WARM
FRONT. BROAD LIFT IS PRETTY STRONG IN OUR NORTHERN AND EASTERN ZONES
ALL NIGHT. AND WITH TEMPERATURES COOLING ALOFT TO SUB ZERO...AGAIN
USING THE ABOVE MENTIONED MODEL BLEND...SNOW WILL BE LIKELY FOR
AREAS NORTH OF OUR MISSOURI RIVER VALLEY COUNTIES. AT THIS TIME...
IT APPEARS UPWARDS OF 3 TO 3.5 INCHES COULD FALL IN AN AXIS FROM
FROM AROUND BROOKINGS...TO WORTHINGTON...TO SPENCER IOWA. LIGHTER
AMOUNTS WILL THEN FOLLOW SUIT ON BOTH SIDES OF THAT AXIS BUT ANY
DEVIATION IN THE STORM TRACK COULD REALLY FOUL UP THIS THINKING. LOW
TEMPERATURES WILL AGAIN NOT LIKELY FALL TOO MUCH FROM DAYTIME
HIGHS...WITH A LOT OF 20S ANTICIPATED. BECAUSE OF TEMPERATURES BELOW
FREEZING COUPLED WITH WARM TEMPERATURES ALOFT...EVEN ON THE SOUTHERN
TRACK SOLUTIONS...AM A BIT CONCERNED ABOUT MORE LIGHT FREEZING RAIN
POTENTIAL LATE SUNDAY NIGHT IN AN AREA FROM CHAMBERLAIN TO LAKE
ANDES.
THEN ON MONDAY AND MONDAY NIGHT...THE AFOREMENTIONED MODEL BLEND
DIVES THE UPPER LOW SOUTHEASTWARD TOWARD TOPEKA KS/KANSAS CITY AREA
BY 12Z TUESDAY. THIS TRACK WOULD BE FAVORABLE FOR GIVING THE
NORTHEAST HALF OF OUR FORECAST AREA ACCUMULATING SNOW EITHER IN THE
ADVISORY OR WARNING CRITERIA CATEGORIES. GFS UPPER QG FORCING IS
MAXIMIZED IN A TRACK JUST SOUTH OF OUR MISSOURI RIVER VALLEY ZONES
WITH STRONG PV FORCING FOLLOWING SUIT. NOW ONE THING TO MENTION...IS
IT IS DIFFICULT TO TELL AT THIS POINT WHERE ANY MESOSCALE TO
MICROSCALE FRONTAL BANDING WILL TAKE PLACE OR ANY POTENTIAL UPPER
INSTABILITY. THE GLOBAL TYPE MODELS HAVE A TENDENCY TO WASH OUT
THESE FEATURES OUT AND THE ONE MODEL THAT COULD SHOW THIS...
THE NAM...WAS NOT USED. SO HEAVIER AMOUNTS OF SNOW IN FRONTAL
INSTABILITY BANDS COULD OCCUR...AND IF THEY DO...RIGHT NOW THE MOST
LIKELY PLACE WOULD PROBABLY BE ALONG AND EAST OF A BROOKINGS SD TO
SPENCER IA LINE. THEREFORE PUT THESE AREAS IN A WINTER STORM WATCH.
AND EVEN WITHOUT THE FRONTAL BANDING...THESE AREAS ADD UP TO AROUND
8 INCHES OF STORM TOTAL SNOW IN A 24 TO 36 HOUR PERIOD. IT REALLY
NEEDS TO BE STRESSED HOWEVER THAT ANY STORM TRACK DEVIATION COULD
HAVE HUGE CONSEQUENCES ON SNOW AMOUNTS. THERE WILL LIKELY BE AN
EXTREMELY SHARP CUTOFF OF PRECIPITATION ON THE SOUTHERN END OF THE
SNOW SHIELD. AND IF THE NAM TURNS OUT TO BE MORE CORRECT IN
PLACEMENT AND KEEPING THINGS FURTHER NORTH...OUR FORECAST AREA WILL
BE MUCH MORE DRY SLOTTED. CONVERSELY...IF THE TRACK HEDGES SOUTH...
THEN WE WILL NEED TO PUT HEAVIER SNOW TOTALS AND HEADLINES TO THE
WEST OF OUR CURRENT WATCH. SO ADJUSTMENTS IN FUTURE FORECASTS WILL
BE LIKELY. /MJF
IN THE EXTENDED PERIOD...TUESDAY THROUGH FRIDAY...THE SYSTEM BEGINS
TO PULL AWAY FROM THE AREA WITH LINGERING LIGHT SNOW...MAINLY IN OUR
EAST...DIMINISHING THROUGH THE DAY. THERMAL PROFILES CONTINUE TO
COOL ON TUESDAY...AND WITH CLOUD COVER AND LIKELY SNOW COVER STAYED
ON THE COOLER SIDE OF GUIDANCE WITH HIGHS IN THE UPPER 20S ALONG THE
MISSOURI RIVER CORRIDOR TO THE LOWER 20S NORTHEAST. A SURFACE RIDGE
AXIS BUILDS SOUTHWARD INTO OUR AREA DURING THE DAY...BECOMING
SITUATED DIRECTLY OVERHEAD ON TUESDAY NIGHT. WITH CLEARING
SKIES...DYING WINDS...AND FRESH SNOW COVER...WENT BELOW ALL BLEND
GUIDANCE...AND IT MAY ACTUALLY BE EVEN COLDER IF THINGS SET UP
RIGHT. AT THIS POINT HAVE LOWS IN THE LOWER SINGLE DIGITS NORTHEAST
TO THE LOWER AND MID TEENS IN THE FAR WEST.
UPPER LEVEL RIDGING BEGINS TO BUILD INTO THE REGION ON
WEDNESDAY...AS THE SURFACE HIGH PRESSURE PUSHES OFF TO THE EAST WITH
A SOUTHERLY LOW LEVEL FLOW DEVELOPING ON THE BACKSIDE OF THE HIGH.
AS A RESULT...TEMPERATURES WILL ATTEMPT TO WARM ACROSS THE
AREA...THOUGH STUNTED BY SNOW COVER. THE BEST WARMING POTENTIAL
LOOKS TO BE IN OUR SOUTHWEST WITH HIGHS INTO THE UPPER
30S...TAPERING DOWN TO THE EAST WITH READINGS ONLY IN THE MID 20S
NORTH AND EAST OF A GENERAL BROOKINGS TO SPENCER LINE. WINDS WILL
BEGIN TO PICK UP ON WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT AS THE
GRADIENT TIGHTENS IN RESPONSE TO A DEVELOPING LOW PRESSURE TROUGH
OVER THE EASTERN ROCKIES/WESTERN HIGH PLAINS. AS A RESULT...IT WILL
BE A MUCH MILDER NIGHT ON WEDNESDAY NIGHT WITH LOWS UPPER 20S WEST
TO MID/UPPER TEENS EAST.
THURSDAY WILL BE THE WARM DAY OF THE WEEK IN A STRONG SOUTHERLY FLOW
OUT AHEAD OF THE AFOREMENTIONED SURFACE TROUGH. AGAIN...DEEPER SNOW
COVER IN SOME AREAS WILL TEMPER HIGHS SOMEWHAT...THOUGH PORTIONS OF
OUR SOUTH CENTRAL SOUTH DAKOTA ZONES MAY MAKE IT UP INTO THE UPPER
40S WHERE PROGGED 925 MB TEMPS WILL REACH JUST EITHER SIDE OF 10C ON
THURSDAY AFTERNOON. BACK TO THE NORTH AND EAST...WHERE THERE IS THE
POTENTIAL FOR DEEPER SNOW COVER...HIGHS WILL MOST LIKELY BE STUCK IN
THE 30S.
ON FRIDAY...THE GFS AND ECMWF IN DECENT AGREEMENT ON BRINGING UPPER
LEVEL ENERGY ACROSS NORTH DAKOTA...PROBABLY KEEPING ANY
PRECIPITATION POTENTIAL TO THE NORTH OF US...THOUGH PULLING A COLD
FRONT THROUGH OUR AREA LATE THURSDAY NIGHT INTO FRIDAY. LOOKS TO BE
A DRY FRONTAL PASSAGE FOR THE MOST PART WITH LIMITED MOISTURE WITH
THE SYSTEM...THOUGH WILL RESULT IN A COOL DOWN FOR FRIDAY.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WINTER STORM WATCH FROM SUNDAY EVENING THROUGH LATE MONDAY NIGHT
FOR SDZ040.
MN...WINTER STORM WATCH FROM SUNDAY EVENING THROUGH LATE MONDAY NIGHT
FOR MNZ071-072-080-081-089-090-097.
IA...WINTER STORM WATCH FROM SUNDAY EVENING THROUGH LATE MONDAY NIGHT
FOR IAZ002-003-014.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1133 AM CST SAT MAR 2 2013
.SHORT TERM...TODAY THROUGH TUESDAY
332 AM CST SAT MAR 2 2013
UPDATED LAST PARAGRAPH ABOUT THE ACCUMULATING SNOW POTENTIAL FOR
SUNDAY NIGHT THROUGH TUESDAY...MENTIONING THAT WINTER STORM WATCHES
MAY BE REQUIRED.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED RIDGING AGAIN OVER THE WESTERN U.S. AND BEGINNING TO ENTER
THE WESTERN PORTION OF THE PLAINS...WHILE TROUGHING STILL
DOMINATED THE EASTERN U.S. A SHORTWAVE TROUGH WAS EVIDENT OVER THE
FORECAST AREA...PRODUCING SOME CIRRUS AHEAD OF IT OVER EASTERN
WISCONSIN. OTHERWISE...THE AIRMASS HAS DRIED OUT QUITE A
BIT...NOTED BY THE 00Z MPX SOUNDING WITH A PRECIPITABLE WATER OF
0.17 INCHES OR 71 PERCENT OF NORMAL. A LIGHT NORTHERLY BREEZE
CONTINUES AHEAD OF A HIGH PRESSURE RIDGE IN FAR WESTERN MINNESOTA.
THIS BREEZE HAS SO FAR KEPT TEMPERATURES FROM COMPLETELY
PLUMMETING. FARTHER WEST...MID AND HIGH CLOUDS WERE INCREASING
ACROSS THE DAKOTAS AHEAD OF THE BUILDING UPPER RIDGE...IN A
GENERAL WARM ADVECTION PATTERN. NO EVIDENCE YET OF PRECIPITATION
FALLING OUT OF THEM...LIKELY DUE TO THE DRY AIR BETWEEN 600-800MB
ON THE 00Z BIS SOUNDING. AIRMASS AROUND THE NORTHERN PLAINS HAS
WARMED UP SOMEWHAT WITH 850MB TEMPS FROM ABR TO MPX AND GRB AROUND
-8C PER 00Z SOUNDINGS. THE MPX AND GRB OBSERVATIONS WERE ABOUT 2C
WARMER THAN WHAT 01.00Z MODELS FORECASTED. WELL OFF TO THE
WEST...A POTENT UPPER TROUGH WAS LOCATED OVER THE EAST PACIFIC
NEAR 45 N 139 W...WHICH WE ARE WATCHING FOR EARLY NEXT WEEK.
SHORT TERM HIGHLIGHTS / CONCERNS...
1. POTENTIAL FOR SOME LIGHT SNOW LATE TONIGHT/SUNDAY MORNING...
THE AREA OF THICKENING MID/HIGH CLOUDS ACROSS THE DAKOTAS WILL
EVENTUALLY SHIFT OVER THE FORECAST AREA TONIGHT AS THE WESTERN U.S.
RIDGE GETS PUSHED EASTWARD. ACCOMPANYING THE MID/HIGH CLOUDS IS SOME
LOW TO MID LEVEL FRONTOGENESIS AND WEAK ISENTROPIC LIFT ON THE
280-285K SURFACES. THE MAIN QUESTION IS IF ANY SNOW THAT IS PRODUCED
OUT OF THESE CLOUDS AND LIFT CAN MAKE IT TO THE SURFACE. THE 02.00Z
GFS/NAM/ECMWF/CANADIAN ARE ALL DRY...SUGGESTING THAT THE LOW LEVEL
DRY AIR LEFT BEHIND BY THE SURFACE RIDGE CROSSING THE FORECAST AREA
WILL BE ENOUGH TO ABSORB THE SNOW. ONLY THE 01.21Z SREF YIELDS A
SMALL POSSIBILITY OF SNOW ACROSS MUCH OF EASTERN MINNESOTA SUNDAY
MORNING. WILL LEAN TOWARDS THE MAJORITY IDEA AND KEEP A DRY FORECAST
GOING.
2. ACCUMULATING SNOW POTENTIAL SUNDAY NIGHT THROUGH TUESDAY...
GOOD MODEL AGREEMENT EXISTS THAT A FRONTOGENETIC BAND OF
PRECIPITATION WILL FORM FROM THE DAKOTAS SOUTHEAST INTO NORTHWEST
IOWA BY LATE SUNDAY. THIS BAND FORMS BECAUSE OF INTENSIFYING WARM
ADVECTION COMBINING WITH PACIFIC MOISTURE...DOWNSTREAM OF THE POTENT
TROUGH CURRENTLY IN THE EAST PACIFIC MOVING INTO MONTANA.
WHERE THE FRONTOGENETIC BAND GOES FROM HERE IN TIME HAS BEEN
PROBLEMATIC THE LAST COUPLE DAYS...AND THERE REMAINS PROBLEMS TODAY.
PART OF THE ISSUE IS SOLELY JUST ON THE POTENT TROUGH TRACK AND
SPEED. THE SPREAD AT 00Z TUESDAY RANGES FROM THE EASTERN DAKOTAS IN
THE 02.00Z NAM...CENTRAL DAKOTAS IN THE 02.00Z UKMET/ECMWF...AND THE
WESTERN DAKOTAS IN THE 02.00Z CANADIAN/GFS. IT IS WORTH NOTING THAT
THE LOCATION FROM ALL MODELS IS DEFINITELY WEST AND SLOWER THAN
THOSE SEEN FROM THE 01.00Z CYCLE. THE FASTER NAM WOULD BRING THE
FRONTOGENETIC SNOW BAND TO MUCH OF THE AREA ON MONDAY...WITH
POTENTIALLY SOME MODERATE TO HEAVY SNOW IN LA CROSSE. HOWEVER...THE
NAM HAS BEEN CONSIDERED AN OUTLIER SOLUTION. FOR THE WESTERN GROUP
OF THE CANADIAN/GFS...THIS GROUP WOULD ONLY BRING SOME LIGHT SNOW TO
A PORTION OF NORTHEAST IOWA AND THE AUSTIN AREA SUNDAY NIGHT. THE
SNOW THEN EXPANDS EAST A LITTLE ON MONDAY AND EXITS TO THE SOUTHEAST
TUESDAY AFTERNOON. FINALLY THE UKMET/ECMWF ARE KIND OF A COMPROMISE
BETWEEN THE GFS/CANADIAN AND THE NAM.
GIVEN THE DEFINITE SLOW DOWN SIGNAL PRESENT IN ALL MODELS WITH THE
UPPER TROUGH...HAVE TRENDED THE FORECAST THIS WAY. THE RESULT IS TO
THE KEEP THE HIGHEST PRECIPITATION CHANCES IN THE FAR WEST
SOUTHEASTERN MINNESOTA COUNTIES INTO NORTHEAST IOWA FOR LATE SUNDAY
NIGHT THROUGH TUESDAY...WITH LOWER CHANCES TO PRACTICALLY DRY BY THE
TIME YOU HEAD EAST TOWARDS I-94. APPEARS THERE COULD BE TWO
PERIODS OF MORE MODERATE SNOWFALL...ONE WITH THE INITIAL WAVE OF
FRONTOGENESIS/WARM ADVECTION...THEN THE SECOND AND FINAL ONE
ACCOMPANYING THE UPPER TROUGH AS IT DIGS SOUTH INTO MISSOURI ON
TUESDAY.
STILL GIVEN THE MODEL VARIABILITY...IT IS HARD TO SPECULATE ON
SNOWFALL AMOUNTS. ONE CONCERN IS THAT THE MAXIMUM QPF WHEREVER THE
FRONTOGENESIS BAND LAYS UP COULD END UP AT OR ABOVE 1 INCH...
ACCORDING TO THE CANADIAN...GFS...NAM AND SREF. THE ECMWF SUGGEST
HALF OF THAT...BUT THE LOWER TOTAL MAY BE A RESULT OF THE 80 KM
HORIZONTAL RESOLUTION AS WELL AS WEAKER FORCING. THE LIQUID QPF
COMBINED WITH SNOW TO WATER RATIOS LIKELY IN THE 10-15 TO 1 RANGE
FOR THIS EVENT WOULD RESULT IN 36 HOUR TOTALS OF 10 TO 12
INCHES...POSSIBLY MORE. THUS...A WINTER STORM WATCH MAY BE REQUIRED.
RIGHT NOW CONFIDENCE IS JUST NOT HIGH ENOUGH TO ISSUE THE WATCH
BECAUSE OF PLACEMENT PROBLEMS WITH THE SNOW BAND.
3. TEMPERATURES THROUGHOUT THE SHORT TERM...
TEMPERATURES TODAY LOOK TO END UP SIMILAR TO YESTERDAY GIVEN PLENTY
OF SUN BUT THE COOLER START AND 850MB TEMPS HOLDING NEARLY STEADY.
TONIGHT COULD GET QUITE CHILLY...PRIMARILY OVER WISCONSIN WHERE THE
MID/HIGH CLOUDS TAKE LONGER TO ARRIVE. STAYED TOWARDS THE COOL SIDE
OF GUIDANCE OVER WISCONSIN. THE DIURNAL CHANGE SHRINKS FOR SUNDAY
THROUGH MONDAY NIGHT...THOUGH READINGS DO LOOK WARMER... WITH PLENTY
OF CLOUDS AROUND FROM THE SYSTEM AFFECTING THE AREA. WENT WITH A
BLEND OF GUIDANCE FOR HIGHS/LOWS SUNDAY THROUGH MONDAY NIGHT.
.LONG TERM...TUESDAY NIGHT THROUGH FRIDAY NIGHT
215 AM CST SAT MAR 2 2013
MODEL AGREEMENT AMONGST THE 02.00Z ECMWF/CANADIAN/GFS AND GFS
ENSEMBLES IS PRETTY GOOD THROUGH THE LONG TERM PERIOD. GENERAL IDEA
IS THAT THE UPPER TROUGH AFFECTING THE AREA ON TUESDAY WILL HEAD
SOUTHEAST INTO THE MID-ATLANTIC REGION BY WEDNESDAY...PUSHED ALONG
BY UPPER RIDGING BUILDING EAST/NORTH INTO THE PLAINS. THUS...DRIER
CONDITIONS ARE ANTICIPATED ACROSS THE ENTIRE AREA FOR TUESDAY NIGHT
INTO WEDNESDAY.
DEFINITE PATTERN SHIFT FORECAST THROUGH THE REST OF THE WEEK WITH
TROUGHING OVER THE WESTERN U.S. AND RIDGING SHIFTING EAST AND
BUILDING OVER THE EASTERN U.S.. IN ADDITION...IT APPEARS THE UPPER
TROUGHING IN THE WESTERN U.S. IS EVENTUALLY GOING TO SPLIT INTO
TWO...WITH THE SOUTHERN PART CUTTING OFF IN THE SOUTHWEST U.S. AND
THE NORTHERN PART BRINGING A COLD FRONT THROUGH THE AREA COME
FRIDAY. PERHAPS WE MAY SEE SOME LIGHT PRECIPITATION WITH THIS
FRONTAL PASSAGE THURSDAY NIGHT INTO FRIDAY...BUT THE FRONT IS
MOISTURE AND FORCING STARVED. THUS...ONLY HAVE 20 PERCENT CHANCES AT
THE PRESENT TIME. OTHERWISE...DRY CONDITIONS PREVAIL. TEMPERATURES
ARE GOING TO BE ON THE RISE AS WELL...ESPECIALLY COME FRIDAY AHEAD
OF THE COLD FRONT. BY FRIDAY...HIGHS APPEAR ABOVE NORMAL. EVEN
BEHIND THE FRONT LOOKING AHEAD TO THE WEEKEND...THE AIRMASS DOES NOT
LOOK THAT COLD GIVEN A PACIFIC FLOW OF AIR IN ITS WAKE.
&&
.AVIATION...THROUGH 18Z SUNDAY
1133 AM CST SAT MAR 2 2013
A SHORT WAVE TROUGH OVER THE NORTHERN PLAINS WILL MOVE SOUTHEAST
THROUGH THE ARE TONIGHT. MID CLOUDS /AROUND 12K FEET/ WILL MOVE
INTO THE AREA LATE THIS AFTERNOON AND EARLY EVENING. THESE CLOUDS
WILL EVENTUALLY LOWER INTO THE 5-8K FOOT RANGE OVERNIGHT AND
REMAIN THERE THROUGH SUNDAY MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
215 AM CST SAT MAR 2 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BOYNE
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1107 AM CST SAT MAR 2 2013
.UPDATE...
QUIET WEATHER IN THE TODAY PERIOD AS HIGH PRESSURE MOVES IN FROM
WESTERN ONTARIO AND MINNESOTA. MAIN CONCERNS ARE SKY COVER AND
TEMPS. VIS SAT SHOWS MOSTLY SUNNY SKIES WEST OF THE LAKE SHORE
COUNTIES AND THE NORTHEAST QUAD OF THE CWA. CLOUDS THOUGH ARE
BETTER SEEN LOOKING AT THE FOG/11-3.9 MICRON PRODUCT. WHEREIN...A
SWATH OF CLOUDS WITH 1700 FT BASES ARE MORE EVIDENT AND ARE
DOWNSTREAM OF KGRB-TO-KFLD. IN ADDITION...THERE ARE LAKE-ENHANCED
CLOUDS WITH 2500-3000 FT BASES THAT ARE PRESENT ACROSS THE LAKE
SHORE COUNTIES.
SATELLITE TRENDS IN CONJUNCTION WITH RH AND WIND PROGS FAVOR
CLOUDS STICKING AROUND IN THE LAKE SHORE COUNTIES AT LEAST UNTIL
THE LOW LEVEL WINDS BECOME MORE N-TO-NW LATE IN THE
AFTERNOON/EVENING. THE SWATH OF CLOUDS DOWN STREAM OF KGRB ARE
EXPECTED TO DRIFT SOUTH WITH TIME TODAY. WITH EROSION ALREADY
EVIDENT AROUND THE EDGES OF THE SWATH...DO ANTICIPATE IT TO THIN
AND SHRINK AS IT DRIFTS SOUTHWARD. NAM AND RAP BUFKIT SOUNDINGS AT
KOSH SUPPORT IT STICKING AROUND WITH THE LOW-LEVEL MOISTURE
PLENTIFUL JUST BELOW THE INVERSION/ALMOST NEAR ISOTHERMAL LEVEL
THAT BEGINS AROUND 900-850 HPA.
RADAR MOSAIC SHOWS A SHORE-PARALLEL LES BAND ACROSS LAKE MICHIGAN.
HOWEVER...GIVEN BUFKIT SOUNDINGS AND WIND PROFILES...DO NOT
ANTICIPATE IT DRIFTING BACK TOWARDS THE SE WI SHORE. ALSO THE
LATEST HRRR AND LOCAL WRF MODEL RUNS SUPPORT THIS AS THEY KEEP ANY
PRECIP MID-LAKE/DOWN INTO IN/IL.
TEMP TRENDS WERE ALSO MODIFIED SLIGHTLY. 925 HPA TEMPS SHOW A
GENERAL CONSENSUS OF AROUND -8 TO -10 C. IN THE WEST HALF OF THE
CWA...THIS WOULD CORRESPOND TO AROUND 27/28 F IF MIXED DOWN DRY
ADIABATICALLY WHICH SEEMS REASONABLE...THOUGH MUST STILL ACCOUNT
FOR SNOW COVER. IN THE EAST HALF OF THE CWA...A BIT MORE TRICKY
GIVEN THE SKY COVER SITUATION. AS SUCH...HIGHS WERE KEPT THERE
BETWEEN 24-26 F BUT WILL MONITOR AS SKIES EVOLVE TODAY.
ET
&&
.AVIATION/18Z TAFS/...
FOR THE EASTERN TAF SITES...CEILINGS WILL LINGER BETWEEN VFR AND
MVFR LEVELS THROUGH THIS AFTERNOON...FINALLY PUSHING SOUTHEAST OF
THE AREA BY 00Z SUNDAY. VFR CONDITIONS THEN EXPECTED TONIGHT AND
SUNDAY. NORTH WINDS WILL LINGER THIS AFTERNOON...BEFORE WEAKENING
AND BECOMING NORTHWEST TONIGHT. LIGHT NORTHWEST WINDS WILL VEER
NORTHEAST BY LATE SUNDAY. MAY SEE A FEW HIGH CLOUDS SUNDAY.
FOR MADISON...EXPECT VFR CONDITIONS THROUGH SUNDAY. NORTH WINDS
WILL WEAKEN AND BECOME LIGHT AND VARIABLE TONIGHT. MAY SEE
SCATTERED HIGH CLOUDS MOVE INTO THE AREA LATER TONIGHT INTO
SUNDAY. LIGHT WINDS WILL GRADUALLY BECOME EAST SUNDAY.
WOOD
&&
.MARINE...
SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 3 AM CST SUNDAY FOR
THE NEARSHORE WATERS OF LAKE MICHIGAN. TIGHT PRESSURE GRADIENT
WILL SLOWLY RELAX THIS AFTERNOON AND TONIGHT...WHICH WILL ALLOW
NORTH WINDS TO GRADUALLY WEAKEN. SUBSEQUENT HIGH WAVES WILL LINGER
THIS AFTERNOON AND INTO TONIGHT...SLOWLY SUBSIDING BY LATER
TONIGHT AS WINDS WEAKEN.
WOOD
&&
.PREV DISCUSSION... /ISSUED 348 AM CST SAT MAR 2 2013/
SHORT TERM...
TODAY AND TONIGHT...FORECAST CONFIDENCE IS MEDIUM.
TEMPERATURES REALLY DROPPED OUT IN PORTIONS OF WESTERN CWA WITH ONLY
WISPY HIGH CLOUDS AND LIGHT WINDS PROVIDING FAVORABLE RADIATIONAL
CONDITIONS. RADAR LOOPS SHOWING MORE FOCUSED SINGLE LAKE-EFFECT SNOW
BAND DRIFTING AWAY FROM THE SE WI SHORELINE...WITH THE WEST EDGE OF
THE BROADER AREA OF FLURRIES EXTENDING FROM SHEBOYGAN TO EASTERN
WALWORTH COUNTY.
OPERATIONAL AND HI-RES/RAPID UPDATE MODELS DIFFER ON HOW FAR EAST
OVER THE LAKE THIS BAND WILL SET-UP FOR TODAY. COLD AIR ADVECTION
DEEPENS EQUILIBRIUM LEVELS TO AROUND 4100 FT WITH LAKE-INDUCED CAPE
OF 165 J/KG TO GO WITH DELTA T/S AROUND 13C THIS AFTERNOON. BUT BY
THIS TIME 1000-900MB WINDS FAVOR A MORE OFFSHORE CONVERGENCE
ZONE...THOUGH CLOSE TO THE WESTERN SHORE. WILL KEEP IDEA OF MAINLY
FLURRIES WITH LOW POPS HUGGING THE SHORE...WHILE KEEPING A WATCHFUL
EYE ON MOVEMENT OF BAND THROUGH THE EARLY MORNING.
CLOUDS WILL EVENTUALLY DECREASE OVER EASTERN CWA AS FLOW BECOMES NNW
AND PUSHES LOW-LEVEL/LAKE ENHANCED MOISTURE EAST OF FORECAST AREA BY
LATE AFTERNOON/EVENING. ALONG WITH COLD AIR ADVECTION MENTIONED
ABOVE...SINGLE DIGIT LOWS RETURN FOR TONIGHT.
SUNDAY AND SUNDAY NIGHT...FORECAST CONFIDENCE MEDIUM TO HIGH
A SHORTWAVE MOVING ACROSS CENTRAL WI ALONG WITH WEAK 850MB WARM AIR
ADVECTION WILL LEAD TO INCREASING MID AND HIGH CLOUDS OVER THE
FORECAST AREA SUN NIGHT. UNCERTAIN ABOUT HOW QUICKLY THE CLOUDS WILL
MOVE IN WHICH WILL AFFECT SUN NIGHT MIN TEMPS. TRENDED A LITTLE
WARMER THAN CONSENSUS AND WARMER THAN THE ECMWF.
MONDAY THROUGH TUESDAY...FORECAST CONFIDENCE MEDIUM TO LOW
A STRONG SHORTWAVE REACHING THE PACIFIC NORTHWEST 00Z SUN WILL TRACK
ACROSS MONTANA AND SLOW DOWN OVER THE NORTHERN PLAINS SUN NIGHT AND
MONDAY...ALONG WITH AN ASSOCIATED SURFACE LOW. MEANWHILE...A
SOUTHERN STREAM UPPER SHORTWAVE WILL CROSS THE CENTRAL ROCKIES AND A
LEE CYCLONE WILL DEVELOP AND MOVE OVER OK/KS ON MON. THE TWO SURFACE
LOWS ARE FORECAST TO BECOME SORT OF AN INVERTED TROUGH AS THE SYSTEM
MOVES ACROSS THE MIDWEST ON TUESDAY. A BAND OF SNOW IS FORECAST TO
DEVELOP ON THE NORTHEAST SIDE OF THIS SPRAWLING LOW PRESSURE TROUGH
AND THEN SHIFT EAST ACROSS SOUTHERN WI AND MAYBE CENTRAL WI MON
NIGHT THROUGH TUE NIGHT.
DELAYED THE ONSET OF CHANCE POPS INTO SOUTH CENTRAL WI UNTIL MONDAY
MORNING DUE TO DRY EASTERLY FLOW IN THE LOW AND MID LEVELS.
THERE IS VERY LITTLE AGREEMENT BETWEEN THE MODELS REGARDING THE
INTENSITY OF THE NORTHERN STREAM UPPER CLOSED LOW...THE TRACK OF THE
SURFACE LOW(S)...WHERE THE PRECIP BAND WILL SET UP AND THE QPF
AMOUNTS. EVEN THE RUN-TO-RUN CONSISTENCY WITH INDIVIDUAL MODELS IS
POOR. THE 00Z ECMWF LOOKS SIMILAR TO THE NAM NOW AND THE GFS AND
CANADIAN MODELS NOW LOOK SOMEWHAT ALIKE. PLAN ON PLENTY OF CHANGES
IN THE UPCOMING FORECASTS.
THIS MAY BE A LONG DURATION SNOW EVENT ONCE AGAIN...WITH ECMWF
HANGING ON TO PRECIP CHANCES THROUGH EARLY WED MORNING IN SOUTHEAST
WI.
HIGHS EXPECTED IN THE LOWER 30S THROUGH WED. INCREASED SKY COVER TO
ACCOUNT FOR THIS SYSTEM IN THE VICINITY OF SOUTHERN WI. INCREASED
MIN TEMPS DUE TO THE CLOUDY SKIES AS WELL.
LONG TERM...
WEDNESDAY THROUGH FRIDAY...FORECAST CONFIDENCE MEDIUM
HIGH PRESSURE WILL MOVE ACROSS THE UPPER MIDWEST ON WED INTO THU.
WARM ADVECTION IN SOUTHERN WI AHEAD OF THE NEXT UPPER TROUGH WILL
LEAD TO TEMPS RISING INTO THE UPPER 30S AND LOWER 40S BY THE END OF
NEXT WEEK. THERE COULD BE SOME LIGHT PRECIP IN THE FORM OF EITHER
RAIN OR SNOW OR DRIZZLE THU NIGHT/FRI WITH THE WARM AIR ADVECTION
PATTERN AND A SHORTWAVE.
AVIATION/12Z TAFS/...
MVFR CLOUD DECK TO HANG ON IN EASTERN TAF SITES UNTIL MID-LATE
AFTERNOON. OCCASIONAL FLURRIES OR A BRIEF LIGHT SNOW SHOWER WILL
AFFECT MKE AND ENW...ENDING AROUND MID-MORNING AS FLOW PUSHES LIGHT
SNOW/FLURRIES OFFSHORE. MAY BE A FEW WIND GUSTS MIXING DOWN THIS
MORNING...BUT THEN WINDS SLOWLY EASE THROUGH THE DAY. NAM SHOWING
SHALLOW LOW-LEVEL MOISTURE BRINGING MVFR DECK BACK IN TONIGHT...BUT
WILL FOLLOW MORE OPTIMISTIC MODEL SOLUTION AND KEEP VFR CONDITIONS
THROUGH THE FORECAST.
MARINE...
NO CHANGE TO SMALL CRAFT ADVISORY. WHILE WINDS HAVE EASED BELOW
CRITERIA...THEY WILL REMAIN STRONG ENOUGH THAT WITH PERSISTENT
NORTHERLY FETCH WILL REQUIRE SOME TIME FOR WAVES TO SUBSIDE.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 3 AM CST SUNDAY FOR LMZ643>646.
&&
$$
UPDATE...ET/WOOD
TODAY/TONIGHT AND AVIATION/MARINE...REM
SUNDAY THROUGH FRIDAY...MRC