Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/13/12
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
839 PM MST WED DEC 12 2012
.UPDATE...
&&
.SHORT TERM...SATELLITE PICTURES ARE SHOWING A PRETTY DECENT
BATCH OF UPPER LEVEL CLOUDINESS OVER THE WESTERN HALF OF COLORADO
AND THE SOUTHEASTERN QUARTER OF THE STATE TOO. THE NEW (00Z) NAM
DOES NOT SEEM TO INITIALIZE THIS VERY WELL? NOT MUCH TO CHANGE
THIS UPDATE.
.AVIATION...WINDS ARE A BIT QUIRKY THIS EVENING. THE LOW LEVEL
PRESSURE GRADIENT IS PRETTY WEAK SO I WOULD EXPECTED THE NORMAL
DRAINAGE PATTERNS TO KICK IN ANY TIME NOW. THEY ARE ALREADY TO
SOME EXTENT IN SOME AREAS...BUT THEY ARE PRETTY LIGHT. RJK
&&
.PREV DISCUSSION... /ISSUED 332 PM MST WED DEC 12 2012/
SHORT TERM...WEST SOUTHWEST FLOW ALOFT CURRENTLY ACROSS REGION
WITH UPPER LEVEL RIDGE OVER COLORADO. MOUNTAIN WAVE PRODUCING
GUSTY WINDS ACROSS MOUNTAINS AND ALONG FOOTHILLS...WITH GUSTS
AROUND 50 MPH OVER THE HIGHER RIDGES. ACROSS PLAINS...WAVE CLOUD
HAD DISSIPATED WHICH ALLOWED FOR DECENT MIXING. THIS ALLOWED
SOUTHWESTERLIES TO MIX TO THE SURFACE WITH SOME GUSTS TO 20 KTS.
LATEST RUC CROSS SECTION SHOWING CROSS MOUNTAIN FLOW OF 40 KTS AT
MOUNTAIN TOP INCREASING TO 45 KTS BY 00Z. SHOULD SEE GUSTY WINDS
CONTINUE ACROSS MOUNTAINS AND FOOTHILLS INTO THE EVENING WITH SOME
GUSTS TO 60 MPH POSSIBLE ACROSS THE HIGHER RIDGES. WESTERLIES
SHOULD ALSO MOVE ONTO THE ADJACENT PLAINS. UPPER LEVEL RIDGE TO
MOVE ONTO THE CENTRAL PLAINS BY MIDNIGHT WITH THE FLOW ALOFT
BECOMING MORE SOUTHWEST. MODELS SHOW THE WINDS ALOFT WEAKENING
THOUGH CROSS MOUNTAIN FLOW REMAINS AT 40 KTS AT MOUNTAIN TOP.
COULD STILL SEE SOME GUSTS ACROSS THE HIGHER RIDGES. WRF SYNTHETIC
SATELLITE IMAGERY SHOW SOME DEVELOPMENT OF A WAVE CLOUD ACROSS THE
SOUTHERN FOOTHILLS DURING THE EVENING SPREADING NORTHEAST ACROSS
THE PLAINS OVERNIGHT. ENOUGH TO MAINTAIN PARTLY CLOUDY CONDITIONS.
ON THURSDAY...SOUTHWEST FLOW ALOFT TO PREVAIL AS UPPER TROUGH
MOVES ONSHORE OVER THE WEST COAST. 600 MB WINDS 30-35 KTS WITH
MOUNTAIN TOP WINDS 20-25 KTS. NOT MUCH OF A MOUNTAIN WAVE EXPECTED
BUT APPEARS THERE WILL BE ENOUGH MIXING BY THE AFTERNOON FOR GUSTY
SOUTHWEST WINDS ACROSS THE MOUNTAINS AND FOOTHILLS. SHOULD ALSO
SEE SOUTHWESTERLIES ACROSS THE PLAINS DURING THE AFTERNOON. SHOULD
AGAIN SEE TEMPERATURES REACH THE 50S ACROSS THE PLAINS...PERHAPS
NOT AS WARM AS TODAY`S READINGS.
LONG TERM...AN UPPER LEVEL LOW OVER SOUTHERN CALIFORNIA THURSDAY
EVENING WILL OPEN UP AND MOVE NORTHEAST OVER THE STATE BY FRIDAY
AFTERNOON. AREAS OF PRECIPITATION WILL BEGIN TO INCREASE FRIDAY
MORNING WITH SNOW IN THE MOUNTAINS AND A MIX OF RAIN AND SNOW OVER
THE PLAINS. THE 700 MB FLOW IS NOT PARTICULARLY FAVORED FOR
SIGNIFICANT ACCUMULATIONS WITH HELP FROM OROGRAPHICS...HOWEVER
GOOD QG VERTICAL VELOCITIES WILL LIKELY HAVE SOME CONVECTIVE
CHARACTERISTIC TO ADD TO ISOLATED AREAS. THE 700 MB FLOW WILL ALSO
TEND TO KEEP MOST OF THE WESTERN PLAINS...THE URBAN CORRIDOR
MOSTLY DRY WILL ALLOWING SOME SHOWERS TO OCCUR FURTHER EAST.
COOLER AIR MOVING IN WITH THE SYSTEM ALONG WITH CLOUD COVER WILL
PRODUCE MAX TEMPERATURES ABOUT 5-10 DEGREES COOLER THAN THURSDAY.
FRIDAY NIGHT INTO SATURDAY...THE SNOW WILL LIKELY CONTINUE IN THE
MOUNTAINS...ALBEIT LIGHT...WITH CLEARING CONDITIONS OVER THE
PLAINS. TOTAL SNOW ACCUMULATIONS FROM FRIDAY MORNING INTO SATURDAY
MORNING FOR THE MOUNTAINS COULD BE IN THE 3-8 INCHES...SO NO NEED
FOR ANY HIGHLIGHT RIGHT NOW. WILL CONTINUE TO MONITOR THE TRACK OF
THIS STORM.
SATURDAY NIGHT THROUGH SUNDAY WILL FEATURE TWO MORE SHORTWAVE
SYSTEMS TO KEEP A GOOD CHANCE OF SNOW FOR THE MOUNTAINS...BUT
LIKELY KEEPING THE PLAINS DRY.
STARTING SUNDAY...MODEL SOLUTIONS START TO SPREAD QUITE FAR APART
FROM EACH OTHER EVEN THOUGH THEY ARE MORE CONSISTENT IN
THEMSELVES. WILL HAVE A SLIGHT CHANCE FOR SNOW CONTINUE IN THE
MOUNTAINS THROUGH MONDAY WITH SLIGHT DRYING AFTERWARD. CONFIDENCE
IS QUITE LOW FOR THIS PERIOD HOWEVER.
AVIATION...SOUTHWESTERLIES HAVE MIXED TO THE SURFACE ACROSS THE
DENVER AIRPORTS...THOUGH THE WESTERLIES HAVEN`T MOVED INTO BJC.
LATEST RAP AND RUC STILL INDICATING A WESTERLY PUSH ACROSS AREA
00Z-02Z. WILL CONTINUE TO SHOW SOME SORT OF A WESTERLY COMPONENT
THROUGH 02Z BEFORE SOUTHWEST DRAINAGE PATTERN DEVELOPS. GUSTY
DOWNSLOPE WINDS SHOULD PREVAIL AT BJC OVERNIGHT. WAVE CLOUD COULD
REDEVELOP SOUTH AND EAST OF THE AREA OVERNIGHT...THOUGH CEILINGS
WILL REMAIN ABOVE 14000 FEET AGL. ON THURSDAY...SOUTHERLY
WINDS TO PREVAIL WITH MORE OF A WEST SOUTHWEST COMPONENT AT BJC.
WINDS COULD BECOME MORE SOUTHEAST AT DEN AND APA.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....KRIEDERMAN
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
928 PM MST MON DEC 10 2012
.UPDATE...IT APPEARS THAT THE NORTHERLY JET MOVING OVER THE STATE
FROM THE NORTHWEST IS GOING TO HAVE ENOUGH DYNAMICS UNDER ITS LEFT
EXIT REGION TO PRODUCE PERSISTENT LIGHT SNOW SHOWERS THROUGH MOST
OF THE NIGHT...EVEN ON THE PLAINS. WILL BE UPDATING THE FORECAST
TO INCLUDE A CHANCE OF SNOW THROUGH MIDNIGHT...THEN A SLIGHT
CHANCE OF SNOW DURING THE PRE-DAWN HOURS. THE SNOW MAY OR MAY NOT
EXTEND ALL THE WAY BACK TO THE FOOTHILLS...DEPENDING ON HOW MUCH
DOWNSLOPE DRYING WILL BE CONTAINED IN THE NORTHWEST WINDS FLOWING
OVER THE MOUNTAINS. MOUNTAIN AREAS PREVIOUSLY HAD SNOW FORECAST
THROUGH MOST OF THE NIGHT...SO NO CHANGES THERE. ACCUMULATIONS ON
THE PLAINS WILL BE LESS THAN AN INCH...AS IT WILL BE A VERY DRY
SNOW THAT IS FALLING.
&&
.AVIATION...WILL BE ADDING SNOW TO THE DENVER AREA TAFS THROUGH
09Z. BAND OF SNOWFALL IS WORKING ITS WAY SOUTHWARD FROM GREELEY AT
THE PRESENT TIME. LIGHT SNOW OR FLURRIES WILL LAST FOR A FEW
HOURS...BUT ACCUMULATIONS SHOULD BE LESS THAN AN INCH.
&&
.PREV DISCUSSION... /ISSUED 320 PM MST MON DEC 10 2012/
SHORT TERM...STILL DEALING WITH A MODERATE NORTHWEST FLOW PATTERN
ACROSS COLORADO AND STILL PLENTY OF MOISTURE UPSTREAM TO KEEP
LIGHT SNOW GOING IN THE MOUNTAINS. DEEPEST MOISTURE WILL BE UNTIL
MIDNIGHT AND THEN GRADUALLY MOISTURE DEPTH GETS MORE SHALLOW
DURING THE DAY ON TUESDAY. WILL KEEP LIKELY POPS IN THE MOUNTAINS
THROUGH EARLY TUESDAY THEN DIMINISHING LATE IN THE PERIOD. CROSS
SECTIONS INDICATE ANOTHER 2-4 INCHES IN THE MOUNTAINS TONIGHT AND
THEN ANOTHER INCH TUESDAY MORNING. AS FOR THE NORTHEAST
PLAINS...THE GUSTY NORTHWEST WINDS WILL DECREASE THIS EVENING AS
WINDS DECOUPLE FROM THE STRONGER FLOW ALOFT AND WEAK SURGE SHIFTS
WINDS A BIT MORE NORTHERLY. RUC AND GFS HINTS AT SOME LOW QPF
OVER PORTIONS OF THE PLAINS...ESPECIALLY OVER THE PALMER DIVIDE.
GIVEN THE NORTHERLY FLOW WILL KEEP A VERY LOW POP IN THOSE
LOCATIONS BUT NOT OVER THE FRONT RANGE. SKIES WILL CLEAR LATER
TONIGHT BEHIND THIS WEAK WAVE.
LONG TERM...UPPER TROF AXIS MOVES INTO CENTAL PLAINS TUESDAY
EVENING WITH MODERATE TO STRONG NORTHWEST FLOW ALOFT ACROSS
COLORADO. SUBSIDENCE MID LEVEL SUBSIDENCE TO SPREAD ACROSS AREA
WITH DECREASING MID LEVEL MOISTURE. WITH INCREASING WARM AIR
ADVECTION AND STABILITY...SHOULD SEE MOUNTAIN SNOW SHOWERS END
DURING THE EVENING. MODELS SHOW WEAK MOUNTAIN WAVE DEVELOPING
OVERNIGHT TUESDAY WITH CROSS MOUNTAIN FLOW INCREASING TO AROUND 50
KTS AT MOUNTAIN TOP INTO EARLY WEDNESDAY MORNING. SHOULD CONTINUE
TO BE GUSTY ACROSS THE MOUNTAINS AND HIGHER FOOTHILLS...THOUGH THE
STRONGEST WINDS APPEAR TO REMAIN ACROSS THE HIGHER RIDGES. SPEEDS
SHOULD REMAIN BELOW HIGH WIND CRITERIA. RIDGE AXIS TO MOVE ACROSS
THE STATE WEDNESDAY INTO THURSDAY WITH WESTERLY FLOW ALOFT
BECOMING MORE SOUTHWEST AS UPPER TROUGH MOVES INTO THE GREAT
BASIN. DRY CONDITIONS TO PREVAIL WEDNESDAY AND THURSDAY WITH
TEMPERATURES EXPECTED TO WARM BACK TO SEASONAL NORMALS. FOR
FRIDAY...BOTH DGEX AND ECMWF SHOW UPPER TROUGH MOVING ACROSS
COLORADO WHILE GFS BRINGS TROUGH ACROSS THE STATE FRIDAY EVENING.
AT THIS TIME NOT SURE WHICH SOLUTIONS WILL BE CORRECT...BUT THERE
IS A GENERAL CONSENSUS OF MOISTURE INCREASING ACROSS COLORADO
ALONG WITH SOME MID LEVEL ASCENT. SHOULD BE ENOUGH FOR A CHANCE OF
MOUNTAIN SNOW. DGEX AND ECMWF ALSO GENERATE SOME LIGHT PRECIP
ACROSS SOUTHERN AND FAR EASTERN COLORADO LATE AFTERNOON AND
EVENING. WILL INCLUDE SOME LOW POPS FAR EASTERN ZONES TO ACCOUNT
FOR THIS WITH DRY CONDITIONS ELSEWHERE.
ON SATURDAY...FLOW ALOFT TO BECOME NORTHWEST AS UPPER TROUGH MOVES
ACROSS CENTRAL PLAINS. MODELS SHOW MAINLY DRY AIRMASS OVER
COLORADO...BUT STILL DECENT MOISTURE AND OROGRAPHICS ACROSS
MOUNTAINS TO KEEP SOME SNOW GOING. OTHERWISE DRY CONDITIONS TO
PREVAIL. FOR SUNDAY AND MONDAY...NORTHWEST FLOW ALOFT TO CONTINUE
ENOUGH OROGRAPHIC SUNDAY FOR A SLIGHT CHANCE OF MOUNTAIN SNOW. .
LATEST ECMWF HI RES MODEL HINTS AT A WEAK DISTURBANCE EMBEDDED IN
THE FLOW MOVING ACROSS THE STATE SUNDAY NIGHT AND MONDAY WHICH
MAY HELP INCREASE SNOW CHANCES ACROSS MOUNTAINS AND BRING A
PERHAPS A SLIGHT CHANCE OF SNOW THE THE PLAINS. LATEST DGEX AND
GFS KEEP THINGS DRY MONDAY. FOR NOW WILL LEAN TOWARD THE DRIER
SOLUTIONS OF THE DGEX AND GFS WITH A SLOW WARMING TREND.
AVIATION...NORTHWEST SURFACE WINDS AT 15-25KT HAVE SURFACED AT
BJC AND APA AND STILL TRYING TO DEVELOP AT KDEN. WILL KEEP THE
IDEA OF SOME BETTER MIXING WITH GUSTY WINDS TO MATERIALIZE AT DEN
FOR A SHORT TIME THROUGH 00Z. FOR TONIGHT A NON DESCRIPT SURFACE
PATTERN WITH A DISORGANIZED FRONT WHICH MAY KEEP SOME WEAK
NORTHERLY FLOW IN THE TERMINALS THROUGH MIDNIGHT BEFORE SLOWLY
RETURNING TO DRAINAGE WINDS LATER IN THE NIGHT. WITH THE MOISTURE
UPSTREAM MAY SEE SOME CEILINGS DIPPING INTO THE 6000-7000 FOOT AGL
RANGE AND MAYBE A BIT LOWER AT APA. WILL STILL KEEP TERMINALS DRY
EXCEPT A VCSH AT APA.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...DANKERS
LONG TERM....D-L
AVIATION...RTG
AREA FORECAST DISCUSSION
NWS MIAMI FL
1001 PM EST WED DEC 12 2012
.UPDATE...
THE EVENING SURFACE ANALYSIS SHOWED A FRONTAL BOUNDARY EXTENDING
SOUTHWEST ACROSS THE FLORIDA PENINSULA NORTH OF OUR LOCAL AREA AND
A DECENT DEWPOINT GRADIENT FROM NORTH TO CENTRAL FLORIDA.
OBSERVATIONS SHOWED MAINLY LIGHT SOUTH-SOUTHWEST FLOW SOUTH OF THE
BOUNDARY ACROSS SOUTH FLORIDA WITH DEWPOINTS RANGING FROM THE
UPPER 60S TO LOWER 70S. RECENTLY ANIMATED WATER VAPOR LOOP SHOWED
A FAIRLY STRONG SHORTWAVE TROUGH BEGINNING TO LIFT NORTHEAST
TOWARD THE CAROLINAS WITH PLENTY OF MID/UPPER MOISTURE SPREADING
NORTHEAST ACROSS THE STATE...WITH THE EXCEPTION BEING THE FLORIDA
PANHANDLE WHERE DRY AIR HAS BEGUN SPREAD EAST IN THE WAKE OF THE
SHORTWAVE TROUGH. THE LATEST RUC ANALYSIS HAS INITIALIZED WELL
WITH THESE SYNOPTIC FEATURES AND GENERALLY INDICATES THE FRONTAL
BOUNDARY CONTINUING TO SLOWLY MAKE ITS WAY SOUTH INTO OUR AREA
THROUGH THE REMAINDER OF THE NIGHT AND INTO THURSDAY. LIGHT WINDS
ALONG WITH THE POTENTIAL FOR SOME CLEARING COULD RESULT IN FOG
DEVELOPMENT THROUGH THE LATE NIGHT HOURS. THE LATEST SREF
PROBABILITIES REFLECT THIS POTENTIAL AND REMAIN QUITE AGGRESSIVE
INDICATING VISIBILITIES DROPPING TO LESS THAN A MILE AFTER 06Z AND
CONTINUING THROUGH DAYBREAK ACROSS THE INLAND LOCATIONS. THE
LATEST FORECAST PACKAGE WAS UPDATED...MAINLY TO REDUCE THE RAIN
CHANCES THIS EVENING. OTHERWISE...THE PREVIOUS FORECAST PACKAGE
REMAINS ON TRACK WITH NO OTHER UPDATES NECESSARY AT THIS TIME.
85/AG
&&
.PREV DISCUSSION... /ISSUED 641 PM EST WED DEC 12 2012/
AVIATION...WEAK COLD FRONT WILL MOVE ACROSS SOUTH FLORIDA EARLY
THURSDAY WITH EXTENSIVE CLOUD FIELD AHEAD OF THE FRONT. VERY
LITTLE SHRA ACTIVITY WITH ABUNDANT MID LEVEL DRY AIR. GUIDANCE
INDICATED IFR CIGS DEVELOPING AFT 06-08Z BUT CONFIDENCE NOT HIGH
ENOUGH TO GO WITH THAT BUT SSW-SW LIGHT WIND FLOW LESS THAN 5 KT
GIVES MORE CREDENCE TO THIS SET UP SO INTRODUCED MVFR CIGS
PERSISTING TO BTWN 13-15Z. SFC WIND WILL SHIFT TO THE NNW BEHIND
THE FRONT AT 8-10KT EARLY THURSDAY AND WILL ATTEMPT TO VEER TO THE
NNE LATE IN THE PERIOD. SO AT THIS TIME, ONLY INDICATED THIS AT KFLL.
KOB
PREV DISCUSSION... /ISSUED 308 PM EST WED DEC 12 2012/
.A FEW STRONG STORMS ARE POSSIBLE NORTH OF ALLIGATOR ALLEY THIS
AFTERNOON INTO EARLY THIS EVENING...
.DRIER AND COOLER WEATHER IS EXPECTED FOR LATE THIS WEEK INTO
THIS WEEKEND...
SHORT TERM...
A COLD FRONT OVER CENTRAL FLORIDA WILL CONTINUE TO MOVE SLOWLY
SOUTH THIS AFTERNOON AND SHOULD BE AROUND THE LAKE OKEECHOBEE AREA
TONIGHT. THIS WILL KEEP THE STEERING FLOW SOUTHWEST OVER THE CWA
THIS AFTERNOON AND KEEP THE DEEP TROPICAL MOISTURE IN PLACE.
AT THE SAME TIME...THE SHORTWAVE OVER THE EASTERN GULF OF MEXICO
WILL CONTINUE TO MOVE EAST THROUGH CENTRAL/SOUTH FLORIDA THIS
AFTERNOON. THESE TWO WEATHER SYSTEMS ALONG WITH THE DEEP TROPICAL
MOISTURE WILL ALLOW FOR SCATTERED SHOWERS AND THUNDERSTORMS TO
DEVELOP OVER MOST OF THE CWA THIS AFTERNOON INTO THIS EVENING WITH
THE HIGHEST CHANCE OVER THE LAKE OKEECHOBEE AREA.
THE 500 MB LEVEL OF THE ATMOSPHERE CONTINUES TO BE IN THE -9C TO
-10C FROM THE SPECIAL 18Z MIA SOUNDING THIS AFTERNOON. THIS SHOULD
ALLOW FOR A FEW STRONG STORMS TO DEVELOP THROUGH THE AFTERNOON AND
EARLY EVENING HOURS...ESPECIALLY AROUND THE LAKE OKEECHOBEE AND
NORTHEAST AREAS OF THE CWA. SO WILL CONTINUE TO MENTION STRONG
STORM WORDING IN THE HWO PRODUCT AND THE NORTHERN ZONES OF THE CWA
FOR THIS AFTERNOON INTO EARLY THIS EVENING.
PATCHY TO AREAS OF FOG ARE ALSO POSSIBLE OVER SOUTH FLORIDA
TONIGHT AHEAD OF THE COLD FRONT...AS THE WINDS WILL BE LIGHT FROM
THE SOUTHWEST ALONG WITH THE DEEP TROPICAL MOISTURE. SO WILL BE
ADDING FOG WORDING TO MOST OF THE CWA FOR LATE TONIGHT INTO EARLY
THURSDAY MORNING.
THURSDAY INTO THIS WEEKEND...
THE COLD FRONT OVER LAKE OKEECHOBEE WILL CONTINUE TO MOVE
SOUTHWARD THROUGH THE CWA THURSDAY MORNING AND INTO THE FLORIDA
KEYS THURSDAY AFTERNOON INTO THURSDAY NIGHT. THIS WILL ALLOW FOR
DRIER AIR TO START TO WORK INTO THE CWA FROM THE NORTH.
HOWEVER...THERE COULD STILL BE A FEW SHOWERS THAT COULD AFFECT THE
EAST COAST METRO AREAS ON THURSDAY. SO WILL CONTINUE THE SLIGHT
CHANCE OF POPS FOR THE EAST COAST METRO AREAS ON THURSDAY...BEFORE
GOING DRY FOR ALL OF SOUTH FLORIDA THURSDAY NIGHT. THE DRY WEATHER
WILL THEN CONTINUE TO REMAIN IN PLACE OVER SOUTH FLORIDA THIS
WEEKEND...AS HIGH PRESSURE BUILDS INTO THE SOUTHEAST UNITED STATES
FROM THE CENTRAL UNITED STATES.
TEMPERATURES WILL ALSO GET BACK TO MORE NEAR NORMAL CONDITIONS
OVER SOUTH FLORIDA THIS WEEKEND WITH HIGHS IN THE 70S TO AROUND 80
AND LOWS IN THE 50S INTERIOR AREAS TO 60S OVER THE METRO AREAS.
LONG TERM...
THE LONG RANGE MODELS CONTINUE TO SHOW A LOW PRESSURE DEVELOPING
IN THE CENTRAL UNITED STATES EARLY NEXT WEEK...BEFORE MOVING INTO
THE SOUTHEAST UNITED STATES BY MIDDLE OF NEXT WEEK. THE MODELS ARE
ALSO SHOWING THAT A STRONG COLD FRONT ASSOCIATED WITH THE LOW WILL
BE MOVING THROUGH SOUTH FLORIDA ON TUESDAY. HOWEVER...THE MODELS
ARE NOW SHOWING THAT MOST OF THE ENERGY WILL NOT BE MORE CLOSER TO
THE LOW AND NOT ALONG THE FRONT. SO WILL KEEP THE SLIGHT CHANCE OF
SHOWERS IN THE FORECAST FOR TUESDAY.
MARINE...
THE WINDS OVER THE LOCAL SOUTH FLORIDA WATERS WILL BE SOUTHERLY
THIS AFTERNOON INTO TONIGHT...BEFORE SWINGING TO A NORTHERLY
DIRECTION THURSDAY INTO FRIDAY. THE SPEEDS WILL ALSO INCREASE FROM
10 TO 15 KNOTS TONIGHT TO 15 TO 20 KNOTS THURSDAY AFTERNOON INTO
FRIDAY. THIS WILL ALLOW FOR THE ATLANTIC SEAS TO INCREASE FROM 2
TO 3 FEET TONIGHT UP TO AROUND 7 FEET BY THURSDAY NIGHT INTO
FRIDAY. THE GULF SIDE SEAS WILL REMAIN BELOW 6 FEET TONIGHT INTO
FRIDAY. SO A SCEC AND OR SCA WILL MORE LIKELY BE NEEDED BY
THURSDAY AFTERNOON INTO THURSDAY NIGHT FOR THE LOCAL WATERS OF
SOUTH FLORIDA.
FIRE WEATHER...
THE RELATIVE HUMIDITIES OVER SOUTH FLORIDA WILL REMAIN ABOVE THE
35 PERCENT CRITICAL VALUE FOR REST OF THE WEEK INTO THIS WEEKEND.
SO NO PROBLEMS ARE EXPECTED WITH THE FIRE WEATHER PRODUCTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 68 76 64 78 / 20 20 10 10
FORT LAUDERDALE 70 78 66 78 / 20 20 10 10
MIAMI 70 79 67 79 / 20 20 10 10
NAPLES 66 76 58 77 / 20 10 - -
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...85/AG
AVIATION/RADAR...30/KOB
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
351 PM EST TUE DEC 11 2012
.DISCUSSION...
TONIGHT...LATEST RAP ANALYSIS SHOWS THE H85-H50 FLOW HAS BECOME
PARALLEL TO THE ORIENTATION OF THE APPROACHING COLD FRONT...A SET UP
THAT SHOULD FORCE IT TO STALL OVER N FL OVERNIGHT. INDEED... FORWARD
MOTION HAS DECREASED OVER THE PAST SVRL HRS. INTERACTION BTWN THE
FRONTAL TROF AND AN H100-H70 RIDGE AXIS OVER CUBA AN THE FL STRAITS
WILL GENERATE A STRONG AND DEEP SW FLOW ACRS CENTRAL FL. THESE WINDS
WILL TAP A DEEP MOISTURE BAND OVER THE SE GOMEX/YUCATAN CHANNEL AND
PULL IT ACRS THE AREA.
POCKETS OF ENHANCED MID LVL VORTICITY/OMEGA AND UPR LVL DIVERGENCE
NOTED WITHIN THE MOISTURE BAND. MODEL SOUNDINGS INDICATE PWAT VALUES
INCREASING TO 2.0" BY 06Z WITH STRAIT LINE HODOGRAPHS THRU DAYBREAK
ALONG AND N OF I-4...H85-H50 LAPSE RATES BTWN 6.0-6.5C/KM. LOSS OF
DAYTIME HEATING WILL REDUCE SFC BUOYANCY...BUT WITH SFC DEWPOINTS
REMAINING IN THE M60S/L70S... PRECIP CHANCES WILL BE HIGH ACRS E
CENT FL. ADDED DYNAMIC SUPPORT ALOFT WILL ENHANCE STORM POTENTIAL...
ESP WHERE MID/UPR LVL CLOUD COVER THINS OUT AND ALLOWS LATE AFTN
HEATING.
WILL GO WITH 80 POPS FROM NW OSCEOLA/N BREVARD NWD...DECREASING TO
60 POPS MARTIN/ST. LUCIE. WARM SW FLOW AND HIGH CLOUD COVER WILL
KEEP MIN TEMPS IN THE M/U60S...A SOLID 10-15F ABV CLIMO.
WEDNESDAY...LITTLE CHANGE TO THE WET WX PATTERN FOR MOST OF THE DAY
AS THE RIDGE OVER THE FL STRAITS CONTINUES TO INTERACT WITH THE
FRONTAL TROF STRUNG OUT ACROSS N FL. A MID LVL SHORT WAVE IS
EXPECTED TO BACK OVER THE SRN PLAINS WILL PUNCH ACRS THE DEEP
SOUTH/NORTHERN GOMEX AND INDUCE WEAK SURFACE LOW ALONG STALLED FRNTL
BNDRY. AS THE LOW PULLS INTO THE ATLC...IT WILL PROVIDE THE
NECESSARY TORQUE TO CRANK THE FRONT INTO CENTRAL FL BY LATE AFTN.
MODERATE TO STRONG UPPER LEVEL FORCING WILL REMAIN IN PLACE AS A
100-140KT LIFTING H25 JET EXTENDING FROM THE CANADIAN MARITIMES TO
THE NW GOMEX DRAGS ITS ASCENDING RIGHT REAR QUADRANT ACRS THE
PENINSULA. LOW LVL CONVERGENCE AHEAD OF THE FRONT COUPLED WITH
APPROACHING SHORTWAVE AND JET STREAK WILL SUPPORT 60-80 POPS THRU
THE DAY. SPC KEEPS CENTRAL FL UNDER A SEE TEXT FOR SVR WX FOR THE
PSBLY OF A FEW STRONG WIND GUSTS WITHIN STORMS. WHILE SOME SHOWERS
AND STORMS MAY CONTAIN HEAVY RAIN...FLOODING CONCERNS REMAIN MINIMAL
WITH ANNUAL PRECIP DEFICITS RANGING FROM 2" TO 12".
WED NIGHT-THURSDAY...SHOWER/STORM ACTIVITY LINGERING INTO WED
EVENING BEFORE PASSING SHORTWAVE HELPS PUSH THE FRONT DOWN THE
PENINSULA OVERNIGHT INTO EARLY THURSDAY. BRIEF COOLDOWN BEHIND THE
FRONT FOR THURSDAY BUT FLOW WILL QUICKLY TAKE ON AN ONSHORE
COMPONENT BY LATER IN THE DAY. HAVE SCATTERED POPS IN FOR EARLY WED
EVENING THEN JUST A SLIGHT POP SOUTHERN FOR COUNTIES THURSDAY
MORNING. LOW TEMPS WED NIGHT RANGING FROM THE MID 50S NORTHWESTERN
SECTIONS TO THE MID 60S SOUTHERN TREASURE COAST. DAYTIME HIGHS
THURSDAY IN THE LOWER 70S NORTH AND MID 70S SOUTHERN SECTIONS OF
EC FL.
PREVIOUS EXTENDED DISCUSSION FOLLOWS...
FRIDAY-MONDAY...THE SURFACE HIGH BEHIND THE FRONT WILL QUICKLY
STRING OUT ACROSS THE DEEP SOUTH AND WESTERN ATLANTIC BY THE END OF
THE WEEK...BRINGING THE FLOW AROUND TO THE EAST BY FRIDAY AND
MODERATING ANY POST-FRONTAL COOLDOWN.
BOTH THE GFS AND ECMWF SHOW ENOUGH LOW LEVEL MOISTURE THAT LOW
TOPPED ONSHORE MOVING SHOWERS MAY BE A POSSIBILITY FRIDAY NIGHT INTO
SATURDAY...HOWEVER WILL KEEP THE MENTION OUT OF THE FORECAST FOR NOW
AS THE EXACT TIMING/COVERAGE OF THESE CAN BE HARD TO PINPOINT MORE
THAN A DAY OR TWO OUT. BY SUNDAY TIMING DIFFERENCE ARISE BETWEEN THE
GFS AND ECMWF IN THE NEXT SHORTWAVE AND ACCOMPANYING SURFACE LOW
THAT MOVES ACROSS THE MIDWEST. HOWEVER BOTH INDICATE THE APPROACH OF
ANOTHER FRONTAL BOUNDARY IN THE SUNDAY/MONDAY TIMEFRAME AND HAVE
INTRODUCE ISOLATED SHOWERS INTO THE FORECAST FOR THOSE TWO DAYS.
SEASONABLE TEMPERATURES THROUGH THE PERIOD WITH HIGHS IN THE
MID-UPPER 70S AND LOWS IN THE 50S.
&&
.AVIATION...THRU 12/03Z...VCTS ALL SITES...AREAS MVFR CIGS...NMRS
MVFR SHRAS/SCT IFR TSRAS...LIFR CIGS/VSBYS ALNG THE COAST BTWN
KOMN-KTIX IN SEA FOG. BTWN 12/03Z-12-06Z...IFR CIGS DVLPG ALL SITES
CONTG THRU 12/18Z...AREAS LIFR CIGS/IFR VSBYS IN FG N OF
KMLB-KISM...MVFR VSBYS IN BR S OF KMLB-KISM.
&&
.MARINE...TONIGHT...LIGHT AND VARIABLE SFC/BNDRY LYR WINDS WILL
INCREASE OUT OF THE S/SW TO 10-15KTS OVERNIGHT AS THE APPROACHING
COLD FRONT STALLS OVER N FL. SEAS 2-3FT NEARSHORE AND 3-4FT
OFFSHORE. NMRS/WDSRPD SHRAS AND SCT TSRAS MOVING OFFSHORE...
INCREASED POTENTIAL FOR SFC G34KTS OR HIGHER
WEDNESDAY...MODERATE TO FRESH S/SW BREEZE THRU MOST OF THE DAY.
WNDSHFT TO W/NW BCMG GENTLE TO MODERATE N OF CAPE CANAVERAL BY MID
AFTN AS THE COLD FRONT BEGINS TO PUSH INTO THE CENTRAL PENINSULA.
SEAS 2-4FT NEARSHORE AND 3-5FT OFFSHORE. NMRS/WDSRPD SHRAS AND SCT
TSRAS MOVING OFFSHORE.
WED NIGHT/THURSDAY...FRONT PUSHES DOWN THE STATE WEDNESDAY NIGHT
INTO THURSDAY. BRIEF NORTHERLY WIND SURGE BEHIND THE FRONT WITH
WINDS PICKING UP NEAR 20KT BEFORE VEERING NORTHEAST AND DECREASING
BACK TO 15-20KT THURSDAY NIGHT. SEAS PICKING UP TO 5 FEET NEAR SHORE
AND UP TO 8 FEET WELL OFFSHORE BEHIND THE FRONT.
PREVIOUS EXTENDED DISCUSSION...
FRI-SUN...PROGRESSIVE FLOW PATTERN WILL BE IN PLACE THROUGH THE
WEEKEND AS THE SURFACE HIGH PUSHES ACROSS THE DEEP SOUTH AND OFF THE
MID ATLANTIC COAST...BRINGING WINDS AROUND TO THE EAST FOR FRIDAY AT
AROUND 15KTS...WITH SPEEDS DROPPING TO AROUND 10KTS INTO SATURDAY AS
THE RIDGE AXIS SINKS FURTHER SOUTH THROUGH THE STATE. BY
SUNDAY...WIND ARE FORECAST TO VEER TO THE SOUTH AND SOUTHWEST AS THE
RIDGE CONTINUES ITS SOUTHERLY MOVEMENT IN ADVANCE OF ANOTHER SYSTEM
MOVING INTO THE SOUTHEAST. DEPENDING ON THE TIMING OF THE NEXT
FRONT...SOUTH-SOUTHWEST WINDS COULD INCREASE TO 15-20KTS BY LATE
SUNDAY AFTERNOON.
WITH WINDS CONTINUING TO VEER THROUGH THE PERIOD...THERE WILL NOT BE
ENOUGH TIME FOR A LONG FETCH TO SET UP AND SEAS ARE EXPECTED TO
SLOWLY SUBSIDE FROM 7-8FT OFFSHORE FRIDAY TO 5-6FT BY SAT EVENING.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 65 74 57 72 / 80 90 40 10
MCO 66 79 58 75 / 80 70 40 10
MLB 69 79 61 76 / 70 70 50 20
VRB 68 80 62 77 / 70 60 50 20
LEE 64 75 54 73 / 80 80 40 10
SFB 66 77 58 74 / 80 80 40 10
ORL 66 78 58 74 / 80 80 40 10
FPR 68 80 62 77 / 60 60 50 20
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...BRAGAW
LONG TERM....GLITTO
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1238 PM EST TUE DEC 11 2012
.SYNOPSIS...
A FRONTAL ZONE WILL REMAIN NEAR THE COAST THROUGH WEDNESDAY NIGHT.
A SERIES OF LOW PRESSURE SYSTEMS WILL MOVE NORTHEASTWARD ALONG THE
FRONT. THE LAST IN THE SERIES OF LOWS IS FORECAST TO BEGIN LIFTING
NORTHEAST OF THE AREA WEDNESDAY NIGHT. DRY AND COOL HIGH PRESSURE
WILL FOLLOW FOR THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
A FRONT WILL CONTINUE TO BE STALLED NEAR THE COAST. THE FRONT WILL
BE PARALLEL TO THE SOUTHWEST FLOW ALOFT. A MID-LEVEL SHORTWAVE
TROUGH OVER THE GULF OF MEXICO SHOULD RESULT IN A MOISTURE
INCREASE LATER THIS AFTERNOON. THE RAP SHOWS THIS INCREASE. THERE
MAY BE ENOUGH MOISTURE FOR RAIN. FORECASTED CHANCE POPS WITH THE
GREATEST CHANCE IN THE SOUTHEAST PART.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
WEDNESDAY IS A CHALLENGING FORECAST IN TERMS OF PLACEMENT OF POPS.
THERE SHOULD BE A SIGNIFICANT EAST/WEST GRADIENT IN MOISTURE...POP
AND QPF. HAVE FORECAST POP TO RANGE FROM 20-30 PERCENT FAR WEST
CWA TO 80-90 PERCENT FAR EAST. THIS DUE TO FRONTAL ZONE OVER THE
AREA AND LOW PRESSURE MOVING NORTH OFF THE COAST DURING THE DAY AS
AN UPPER LEVEL SHORT WAVE APPROACHES THE AREA. THE SHORT WAVE WILL
CROSS THE AREA WEDNESDAY NIGHT AND MOISTURE/PRECIPITATION WILL
MOVE EAST. SKIES WILL CLEAR THURSDAY MORNING AND THE PERIOD
THURSDAY THROUGH FRIDAY NIGHT WILL BE DRY AND MOSTLY CLEAR AS HIGH
PRESSURE BUILDS OVER THE AREA. TEMPERATURES SHOULD BE CLOSE TO
GUIDANCE VALUES.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
HIGH PRESSURE OVER THE AREA ON SATURDAY WILL MOVE OFF THE COAST ON
SUNDAY. THE MODELS SHOW A MOISTURE INCREASE SUNDAY AS A COLD FRONT
MOVES INTO THE AREA FROM THE WEST. WILL INCREASE POPS TO 20-35
PERCENT SATURDAY NIGHT INTO SUNDAY NIGHT TO ACCOUNT FOR POSSIBLE
SHOWER ACTIVITY ASSOCIATED WITH THE FRONT. MODELS DEVELOP A LOW
PRESSURE SYSTEM AHEAD OF A CLOSE UPPER LOW OVER THE SOUTHERN
PLAINS. THIS IS FORECAST IN THE MONDAY/TUESDAY TIME FRAME WITH THE
GFS FASTER THAN THE ECMWF. WILL INCREASE POPS AGAIN ON TUESDAY
INTO THE 30 PERCENT RANGE BUT THERE IS HIGH UNCERTAINTY AT THIS
TIME WITH RESPECT TO THIS FEATURE...ESPECIALLY THE TIMING. EXPECT
TEMPERATURES ABOVE NORMAL THROUGH SUNDAY THEN CLOSER TO NORMAL
MONDAY AND TUESDAY AFTER THE FRONTAL PASSAGE.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
A COLD FRONT WILL CONTINUE TO PUSH EASTWARD THIS AFTERNOON ALLOWING
DRIER AIR TO ENTER THE REGION. THE FRONT WILL STALL OFFSHORE OVERNIGHT
AND LOW PRESSURE WILL DEVELOP ON THE FRONT LATE TONIGHT AND CONTINUE
INTO WEDNESDAY. THIS WILL BRING DEEPER MOISTURE IN AFTER MIDNIGHT
AND WEDGE LIKE CONDITIONS ARE EXPECTED DURING THE DAY WEDNESDAY.
VFR CONDITIONS ARE EXPECTED INITIALLY WITH SCATTERED TO BROKEN CLOUDS
8-10 KT FT. CIGS WILL LOWER TO 3-4 KFT AFTER MIDNIGHT AND MVFR CIGS
NEAR 2 KFT SHOULD BECOME WIDESPREAD BY 12Z WEDNESDAY MORNING. EXPECT
MAINLY VFR VSBYS THIS AFTERNOON THROUGH THE OVERNIGHT PERIOD AS CLOUD
COVER INCREASES ALTHOUGH GFS AND NAM MOS GUIDANCE BROUGHT IFR-MVFR
VSBYS IN FOG WEDNESDAY MORNING WHILE GFS LAMP GUIDANCE HAD NONE WITH
A GOOD AMOUNT OF CLOUD COVER. LEANED MORE TOWARD THE LAMP GUIDANCE
WITH VERY LITTLE FOG. RAIN CHANCES EXPECTED TO INCREASE WEDNESDAY
MORNING BUT DECIDED TO JUST SAY SHOWERS IN THE VICINITY DUE TO
UNCERTAINTY AS TO LOCATION AND TIMING. BUT LIGHT RAIN IS POSSIBLE
BY LATE WEDNESDAY MORNING AND EARLY AFTERNOON AND THIS COULD RESTRICT
VSBYS TO THE MVFR CATEGORY.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE IN SHOWERS
ASSOCIATED WITH A WAVE OF LOW PRESSURE LIFTING NORTHWARD WEDNESDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1233 PM EST TUE DEC 11 2012
.SYNOPSIS...
A FRONTAL ZONE WILL REMAIN NEAR THE COAST THROUGH WEDNESDAY NIGHT.
A SERIES OF LOW PRESSURE SYSTEMS WILL MOVE NORTHEASTWARD ALONG THE
FRONT. THE LAST IN THE SERIES OF LOWS IS FORECAST TO BEGIN LIFTING
NORTHEAST OF THE AREA WEDNESDAY NIGHT. DRY AND COOL HIGH PRESSURE
WILL FOLLOW FOR THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
A FRONT WILL CONTINUE TO BE STALLED NEAR THE COAST. THE FRONT WILL
BE PARALLEL TO THE SOUTHWEST FLOW ALOFT. A MID-LEVEL SHORTWAVE
TROUGH OVER THE GULF OF MEXICO SHOULD RESULT IN A MOISTURE
INCREASE LATER THIS AFTERNOON. THE RAP SHOWS THIS INCREASE. THERE
MAY BE ENOUGH MOISTURE FOR RAIN. FORECASTED CHANCE POPS WITH THE
GREATEST CHANCE IN THE SOUTHEAST PART.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
WEDNESDAY IS A CHALLENGING FORECAST IN TERMS OF PLACEMENT OF POPS.
THERE SHOULD BE A SIGNIFICANT EAST/WEST GRADIENT IN MOISTURE...POP
AND QPF. HAVE FORECAST POP TO RANGE FROM 20-30 PERCENT FAR WEST
CWA TO 80-90 PERCENT FAR EAST. THIS DUE TO FRONTAL ZONE OVER THE
AREA AND LOW PRESSURE MOVING NORTH OFF THE COAST DURING THE DAY AS
AN UPPER LEVEL SHORT WAVE APPROACHES THE AREA. THE SHORT WAVE WILL
CROSS THE AREA WEDNESDAY NIGHT AND MOISTURE/PRECIPITATION WILL
MOVE EAST. SKIES WILL CLEAR THURSDAY MORNING AND THE PERIOD
THURSDAY THROUGH FRIDAY NIGHT WILL BE DRY AND MOSTLY CLEAR AS HIGH
PRESSURE BUILDS OVER THE AREA. TEMPERATURES SHOULD BE CLOSE TO
GUIDANCE VALUES.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
HIGH PRESSURE OVER THE AREA ON SATURDAY WILL MOVE OFF THE COAST ON
SUNDAY. THE MODELS SHOW A MOISTURE INCREASE SUNDAY AS A COLD FRONT
MOVES INTO THE AREA FROM THE WEST. WILL INCREASE POPS TO 20-35
PERCENT SATURDAY NIGHT INTO SUNDAY NIGHT TO ACCOUNT FOR POSSIBLE
SHOWER ACTIVITY ASSOCIATED WITH THE FRONT. MODELS DEVELOP A LOW
PRESSURE SYSTEM AHEAD OF A CLOSE UPPER LOW OVER THE SOUTHERN
PLAINS. THIS IS FORECAST IN THE MONDAY/TUESDAY TIME FRAME WITH THE
GFS FASTER THAN THE ECMWF. WILL INCREASE POPS AGAIN ON TUESDAY
INTO THE 30 PERCENT RANGE BUT THERE IS HIGH UNCERTAINTY AT THIS
TIME WITH RESPECT TO THIS FEATURE...ESPECIALLY THE TIMING. EXPECT
TEMPERATURES ABOVE NORMAL THROUGH SUNDAY THEN CLOSER TO NORMAL
MONDAY AND TUESDAY AFTER THE FRONTAL PASSAGE.
&&
.AVIATION /17Z TUESDAY THROUGH SATURDAY/...
COLD FRONT PUSHING THROUGH THE AREA THIS MORNING WITH DRIER AIR
WORKING IN FROM THE WEST. THIS HAS BROUGHT MAINLY VFR CIGS ABOVE
3 KFT TO THE TAF SITES. HOWEVER...IR SATELLITE SHOWS DEEPER MOISTURE
MOVING NORTHEAST FROM THE GULF AND THIS MAY LOWER CIGS BACK BELOW
3 KFT LATER THIS AFTERNOON OR EARLY THIS EVENING. SINCE TIMING IS
AN ISSUE...DECIDED TO KEEP VFR CONDITIONS DURING THIS TIME PERIOD.
SOUTHWESTERLY FLOW ALOFT WILL KEEP A BLANKET OF MID AND HIGH
CLOUDS OVER THE AREA THROUGH THE FORECAST PERIOD. WINDS WILL BE
FROM THE WEST AROUND 5 TO 8 KNOTS THROUGH THE DAY BEFORE
DIMINISHING AND TURNING MORE NORTHERLY LATE IN THE FORECAST
PERIOD. SOME ISOLATED SHOWERS CANNOT BE RULED OUT BUT EVEN IF RAIN
DOES OCCUR IT SHOULD NOT RESULT IN ANY REDUCTION OF VSBYS/CIGS.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE IN SHOWERS
ASSOCIATED WITH A WAVE OF LOW PRESSURE LIFTING NORTHWARD TONIGHT
AND WEDNESDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1041 AM EST TUE DEC 11 2012
.SYNOPSIS...
A FRONTAL ZONE WILL REMAIN NEAR THE COAST THROUGH WEDNESDAY NIGHT.
A SERIES OF LOW PRESSURE SYSTEMS WILL MOVE NORTHEASTWARD ALONG THE
FRONT. THE LAST IN THE SERIES OF LOWS IS FORECAST TO BEGIN LIFTING
NORTHEAST OF THE AREA WEDNESDAY NIGHT. DRY AND COOL HIGH PRESSURE
WILL FOLLOW FOR THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
THIS MORNING...A FRONTAL BOUNDARY WILL DRIFT SLOWLY EASTWARD AS
THE UPPER FLOW CONTINUES TO BE SOUTHWEST. THEREFORE...THERE SHOULD
NOT BE MUCH TO PUSH THE COLD FRONT. 13 KM RUC DOES SHOW SOME LOW
LEVEL COLD AIR ADVECTION AT 925 MB. MADE MINOR TWEAKS TO TEMPS
USING LATEST MAV GUIDANCE AND RAN MAX TEMP SMART TOOL. NOT MUCH
CHANGE THOUGH. DECIDED TO KEEP INCREASING POPS MAINLY SOUTH AND
EAST PORTIONS AS DEEPER MOISTURE ON IR SATELLITE MOVING TOWARD
THE REGION.
THIS AFTERNOON....THE FRONT WILL BE STALLED NEAR THE COAST. THE
FRONT WILL BE PARALLEL TO THE SOUTHWEST FLOW ALOFT. A MID-LEVEL
SHORTWAVE TROUGH OVER THE GULF OF MEXICO SHOULD RESULT IN A
MOISTURE INCREASE LATER THIS AFTERNOON. THE RAP SHOWS THIS
INCREASE. THERE MAY BE ENOUGH MOISTURE FOR RAIN. FORECASTED CHANCE
POPS WITH THE GREATEST CHANCE IN THE SOUTHEAST PART.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
EXPECT A CONTINUED SERIES OF LOW PRESSURE SYSTEMS MOVING
NORTHEASTWARD ALONG THE STALLED FRONTAL ZONE. THE MODELS GENERALLY
SHOW DEEPER MOISTURE JUST EAST OF THE FORECAST AREA WITH THE
FARTHEST EXTENT WESTWARD WEDNESDAY AND WEDNESDAY NIGHT ASSOCIATED
WITH THE MAIN MID-LEVEL SHORTWAVE TROUGH. THE NAM...GFS...AND
ECMWF APPEAR TO INDICATE ENOUGH MOISTURE IN THE EAST PART FOR
LIKELY POPS WEDNESDAY OR WEDNESDAY NIGHT. THE GUIDANCE CONSENSUS
SUPPORTED POPS OF LIKELY EAST TO CHANCE WEST. THERE WILL BE A
TIGHT MOISTURE GRADIENT FROM WEST TO EAST AND THIS MAKES FORECAST
CONFIDENCE LOW. THE GUIDANCE TEMPERATURES APPEAR TOO WARM
WEDNESDAY BECAUSE OF A WEDGE PATTERN. OTHERWISE...USED THE
CONSENSUS.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
HIGH PRESSURE OVER THE AREA ON SATURDAY WILL MOVE OFF THE COAST ON
SUNDAY. THE MODELS SHOW A MOISTURE INCREASE SUNDAY AS A COLD FRONT
MOVES INTO THE AREA FROM THE WEST. WILL INCREASE POPS TO 20-35
PERCENT SATURDAY NIGHT INTO SUNDAY NIGHT TO ACCOUNT FOR POSSIBLE
SHOWER ACTIVITY ASSOCIATED WITH THE FRONT. MODELS DEVELOP A LOW
PRESSURE SYSTEM AHEAD OF A CLOSE UPPER LOW OVER THE SOUTHERN
PLAINS. THIS IS FORECAST IN THE MONDAY/TUESDAY TIME FRAME WITH THE
GFS FASTER THAN THE ECMWF. WILL INCREASE POPS AGAIN ON TUESDAY
INTO THE 30 PERCENT RANGE BUT THERE IS HIGH UNCERTAINTY AT THIS
TIME WITH RESPECT TO THIS FEATURE...ESPECIALLY THE TIMING. EXPECT
TEMPERATURES ABOVE NORMAL THROUGH SUNDAY THEN CLOSER TO NORMAL
MONDAY AND TUESDAY AFTER THE FRONTAL PASSAGE.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
COLD FRONT PUSHING THROUGH THE AREA THIS MORNING WITH DRIER AIR
WORKING IN FROM THE WEST. THIS HAS BROUGHT MAINLY VFR CIGS ABOVE
3 KFT TO THE TAF SITES. HOWEVER...IR SATELLITE SHOWS DEEPER MOISTURE
MOVING NORTHEAST FROM THE GULF AND THIS MAY LOWER CIGS BACK BELOW
3 KFT LATER THIS AFTERNOON OR EARLY THIS EVENING. SINCE TIMING IS
AN ISSUE...DECIDED TO KEEP VFR CONDITIONS DURING THIS TIME PERIOD.
SOUTHWESTERLY FLOW ALOFT WILL KEEP A BLANKET OF MID AND HIGH
CLOUDS OVER THE AREA THROUGH THE FORECAST PERIOD. WINDS WILL BE
FROM THE WEST AROUND 5 TO 8 KNOTS THROUGH THE DAY BEFORE
DIMINISHING AND TURNING MORE NORTHERLY LATE IN THE FORECAST
PERIOD. SOME ISOLATED SHOWERS CANNOT BE RULED OUT BUT EVEN IF RAIN
DOES OCCUR IT SHOULD NOT RESULT IN ANY REDUCTION OF VSBYS/CIGS.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE IN SHOWERS
ASSOCIATED WITH A WAVE OF LOW PRESSURE LIFTING NORTHWARD TONIGHT
AND WEDNESDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
911 AM EST TUE DEC 11 2012
.SYNOPSIS...
A FRONTAL ZONE WILL REMAIN NEAR THE COAST THROUGH WEDNESDAY NIGHT.
A SERIES OF LOW PRESSURE SYSTEMS WILL MOVE NORTHEASTWARD ALONG THE
FRONT. THE LAST IN THE SERIES OF LOWS IS FORECAST TO BEGIN LIFTING
NORTHEAST OF THE AREA WEDNESDAY NIGHT. DRY AND COOL HIGH PRESSURE
WILL FOLLOW FOR THURSDAY AND FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THIS MORNING...A FRONTAL BOUNDARY WILL DRIFT SLOWLY EASTWARD AS
THE UPPER FLOW CONTINUES TO BE SOUTHWEST. THEREFORE...THERE SHOULD
NOT BE MUCH TO PUSH THE COLD FRONT. 13 KM RUC DOES SHOW SOME LOW
LEVEL COLD AIR ADVECTION AT 925 MB. MADE MINOR TWEAKS TO TEMPS
USING LATEST MAV GUIDANCE AND RAN MAX TEMP SMART TOOL. NOT MUCH
CHANGE THOUGH. DECIDED TO KEEP INCREASING POPS MAINLY SOUTH AND
EAST PORTIONS AS DEEPER MOISTURE ON IR SATELLITE MOVING TOWARD
THE REGION.
THIS AFTERNOON....THE FRONT WILL BE STALLED NEAR THE COAST. THE
FRONT WILL BE PARALLEL TO THE SOUTHWEST FLOW ALOFT. A MID-LEVEL
SHORTWAVE TROUGH OVER THE GULF OF MEXICO SHOULD RESULT IN A
MOISTURE INCREASE LATER THIS AFTERNOON. THE RAP SHOWS THIS
INCREASE. THERE MAY BE ENOUGH MOISTURE FOR RAIN. FORECASTED CHANCE
POPS WITH THE GREATEST CHANCE IN THE SOUTHEAST PART.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
EXPECT A CONTINUED SERIES OF LOW PRESSURE SYSTEMS MOVING
NORTHEASTWARD ALONG THE STALLED FRONTAL ZONE. THE MODELS GENERALLY
SHOW DEEPER MOISTURE JUST EAST OF THE FORECAST AREA WITH THE
FARTHEST EXTENT WESTWARD WEDNESDAY AND WEDNESDAY NIGHT ASSOCIATED
WITH THE MAIN MID-LEVEL SHORTWAVE TROUGH. THE NAM...GFS...AND
ECMWF APPEAR TO INDICATE ENOUGH MOISTURE IN THE EAST PART FOR
LIKELY POPS WEDNESDAY OR WEDNESDAY NIGHT. THE GUIDANCE CONSENSUS
SUPPORTED POPS OF LIKELY EAST TO CHANCE WEST. THERE WILL BE A
TIGHT MOISTURE GRADIENT FROM WEST TO EAST AND THIS MAKES FORECAST
CONFIDENCE LOW. THE GUIDANCE TEMPERATURES APPEAR TOO WARM
WEDNESDAY BECAUSE OF A WEDGE PATTERN. OTHERWISE...USED THE
CONSENSUS.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
THE LATEST GFS AND ECMWF AGREE SHOWING DRY RIDGING BECOMING
DOMINATE THURSDAY AND CONTINUING OVER THE AREA FRIDAY. THE MODELS
SHOW A MOISTURE INCREASE SATURDAY WITH A FRONT IN THE AREA SUNDAY.
THE GFS ENSEMBLE MEANS SUPPORT LOW POPS AT THIS TIME. EXPECT
TEMPERATURES ABOVE NORMAL PRIOR TO FRONTAL PASSAGE.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
COLD FRONT PUSHING THROUGH THE AREA THIS MORNING WITH DRIER AIR
WORKING IN FROM THE WEST. THIS HAS BROUGHT MAINLY VFR CIGS ABOVE
3 KFT TO THE TAF SITES. HOWEVER...IR SATELLITE SHOWS DEEPER MOISTURE
MOVING NORTHEAST FROM THE GULF AND THIS MAY LOWER CIGS BACK BELOW
3 KFT LATER THIS AFTERNOON OR EARLY THIS EVENING. SINCE TIMING IS
AN ISSUE...DECIDED TO KEEP VFR CONDITIONS DURING THIS TIME PERIOD.
SOUTHWESTERLY FLOW ALOFT WILL KEEP A BLANKET OF MID AND HIGH
CLOUDS OVER THE AREA THROUGH THE FORECAST PERIOD. WINDS WILL BE
FROM THE WEST AROUND 5 TO 8 KNOTS THROUGH THE DAY BEFORE
DIMINISHING AND TURNING MORE NORTHERLY LATE IN THE FORECAST
PERIOD. SOME ISOLATED SHOWERS CANNOT BE RULED OUT BUT EVEN IF RAIN
DOES OCCUR IT SHOULD NOT RESULT IN ANY REDUCTION OF VSBYS/CIGS.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE IN SHOWERS
ASSOCIATED WITH A WAVE OF LOW PRESSURE LIFTING NORTHWARD TONIGHT
AND WEDNESDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
635 AM EST TUE DEC 11 2012
.SYNOPSIS...
A FRONTAL ZONE WILL REMAIN NEAR THE COAST THROUGH WEDNESDAY NIGHT.
A SERIES OF LOW PRESSURE SYSTEMS WILL MOVE NORTHEASTWARD ALONG THE
FRONT. THE LAST IN THE SERIES OF LOWS IS FORECAST TO BEGIN LIFTING
NORTHEAST OF THE AREA WEDNESDAY NIGHT. DRY AND COOL HIGH PRESSURE
WILL FOLLOW FOR THURSDAY AND FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE FRONT WILL BE STALLED NEAR THE COAST TODAY. THE FRONT WILL BE
PARALLEL TO THE SOUTHWEST FLOW ALOFT. A MID-LEVEL SHORTWAVE TROUGH
OVER THE GULF OF MEXICO EARLY THIS MORNING SHOULD RESULT IN A
MOISTURE INCREASE LATER THIS AFTERNOON. THE RAP SHOWS THIS
INCREASE. THERE MAY BE ENOUGH MOISTURE FOR RAIN. FORECASTED CHANCE
POPS WITH THE GREATEST CHANCE IN THE SOUTHEAST PART. USED THE
GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
EXPECT A CONTINUED SERIES OF LOW PRESSURE SYSTEMS MOVING
NORTHEASTWARD ALONG THE STALLED FRONTAL ZONE. THE MODELS GENERALLY
SHOW DEEPER MOISTURE JUST EAST OF THE FORECAST AREA WITH THE
FARTHEST EXTENT WESTWARD WEDNESDAY AND WEDNESDAY NIGHT ASSOCIATED
WITH THE MAIN MID-LEVEL SHORTWAVE TROUGH. THE NAM...GFS...AND
ECMWF APPEAR TO INDICATE ENOUGH MOISTURE IN THE EAST PART FOR
LIKELY POPS WEDNESDAY OR WEDNESDAY NIGHT. THE GUIDANCE CONSENSUS
SUPPORTED POPS OF LIKELY EAST TO CHANCE WEST. THERE WILL BE A
TIGHT MOISTURE GRADIENT FROM WEST TO EAST AND THIS MAKES FORECAST
CONFIDENCE LOW. THE GUIDANCE TEMPERATURES APPEAR TOO WARM
WEDNESDAY BECAUSE OF A WEDGE PATTERN. OTHERWISE...USED THE
CONSENSUS.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
THE LATEST GFS AND ECMWF AGREE SHOWING DRY RIDGING BECOMING
DOMINATE THURSDAY AND CONTINUING OVER THE AREA FRIDAY. THE MODELS
SHOW A MOISTURE INCREASE SATURDAY WITH A FRONT IN THE AREA SUNDAY.
THE GFS ENSEMBLE MEANS SUPPORT LOW POPS AT THIS TIME. EXPECT
TEMPERATURES ABOVE NORMAL PRIOR TO FRONTAL PASSAGE.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
COLD FRONT PUSHING THROUGH THE AREA THIS MORNING WITH LINGERING MVFR
AND LOW VFR CIGS. EXPECT MVFR CIGS ABOVE 2000 FT 12Z-15Z THEN CIGS
LIFT TO VFR AS DRIER AIR WORKS INTO THE REGION. SOUTHWESTERLY FLOW
ALOFT WILL KEEP A BLANKET OF MID AND HIGH CLOUDS OVER THE AREA
THROUGH THE FORECAST PERIOD. WINDS WILL BE FROM THE WEST AROUND 5
TO 8 KNOTS THROUGH THE DAY BEFORE DIMINISHING AND TURNING MORE
NORTHERLY LATE IN THE FORECAST PERIOD. SOME ISOLATED SHOWERS
CANNOT BE RULED OUT BUT EVEN IF RAIN DOES OCCUR IT SHOULD NOT
RESULT IN ANY REDUCTION OF VSBYS/CIGS.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE IN SHOWERS
ASSOCIATED WITH A WAVE OF LOW PRESSURE LIFTING NORTHWARD TONIGHT
AND WEDNESDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
99
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
552 AM EST TUE DEC 11 2012
.SYNOPSIS...
A FRONTAL ZONE WILL REMAIN NEAR THE COAST THROUGH WEDNESDAY NIGHT.
A SERIES OF LOW PRESSURE SYSTEMS WILL MOVE NORTHEASTWARD ALONG THE
FRONT. THE LAST IN THE SERIES OF LOWS IS FORECAST TO BEGIN LIFTING
NORTHEAST OF THE AREA WEDNESDAY NIGHT. DRY AND COOL HIGH PRESSURE
WILL FOLLOW FOR THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH TODAY/...
THE FRONT WILL BE STALLED NEAR THE COAST TODAY. THE FRONT WILL BE
PARALLEL TO THE SOUTHWEST FLOW ALOFT. A MID-LEVEL SHORTWAVE TROUGH
OVER THE GULF OF MEXICO EARLY THIS MORNING SHOULD RESULT IN A
MOISTURE INCREASE LATER THIS AFTERNOON. THE RAP SHOWS THIS
INCREASE. THERE MAY BE ENOUGH MOISTURE FOR RAIN. FORECASTED CHANCE
POPS WITH THE GREATEST CHANCE IN THE SOUTHEAST PART. USED THE
GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
EXPECT A CONTINUED SERIES OF LOW PRESSURE SYSTEMS MOVING
NORTHEASTWARD ALONG THE STALLED FRONTAL ZONE. THE MODELS GENERALLY
SHOW DEEPER MOISTURE JUST EAST OF THE FORECAST AREA WITH THE
FARTHEST EXTENT WESTWARD WEDNESDAY AND WEDNESDAY NIGHT ASSOCIATED
WITH THE MAIN MID-LEVEL SHORTWAVE TROUGH. THE NAM...GFS...AND
ECMWF APPEAR TO INDICATE ENOUGH MOISTURE IN THE EAST PART FOR
LIKELY POPS WEDNESDAY OR WEDNESDAY NIGHT. THE GUIDANCE CONSENSUS
SUPPORTED POPS OF LIKELY EAST TO CHANCE WEST. THERE WILL BE A
TIGHT MOISTURE GRADIENT FROM WEST TO EAST AND THIS MAKES FORECAST
CONFIDENCE LOW. THE GUIDANCE TEMPERATURES APPEAR TOO WARM
WEDNESDAY BECAUSE OF A WEDGE PATTERN. OTHERWISE...USED THE
CONSENSUS.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
THE LATEST GFS AND ECMWF AGREE SHOWING DRY RIDGING BECOMING
DOMINATE THURSDAY AND CONTINUING OVER THE AREA FRIDAY. THE MODELS
SHOW A MOISTURE INCREASE SATURDAY WITH A FRONT IN THE AREA SUNDAY.
THE GFS ENSEMBLE MEANS SUPPORT LOW POPS AT THIS TIME. EXPECT
TEMPERATURES ABOVE NORMAL PRIOR TO FRONTAL PASSAGE.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
COLD FRONT REMAINS JUST WEST OF THE TERMINALS BUT WILL PUSH EAST
DURING THE 06Z-12Z TIME FRAME. VFR CONDITIONS TO START THE
FORECAST BUT EXPECT MVFR CIGS TO ACCOMPANY THE FRONTAL ZONE AS IT
MOVES EAST ACROSS THE AREA. MVFR CIGS EXPECTED 09Z-15Z WITH
POSSIBLE IFR CIGS AGS/DNL. LIGHT WEST TO SOUTHWEST WINDS THROUGH
15Z THEN PICKING UP FROM THE WEST AROUND 5 TO 8 KNOTS. COLD FRONT
TO STALL EAST OF THE AREA TODAY AND EXPECT MID AND HIGH CLOUDS TO
CONTINUE TO PROVIDE A VFR CLOUD DECK THROUGH THE END OF THE
FORECAST PERIOD.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE IN SHOWERS
ASSOCIATED WITH A WAVE OF LOW PRESSURE LIFTING NORTHWARD TUESDAY
NIGHT THROUGH WEDNESDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
243 AM EST TUE DEC 11 2012
.SYNOPSIS...
A FRONTAL ZONE WILL REMAIN NEAR THE COAST THROUGH WEDNESDAY NIGHT.
A SERIES OF LOW PRESSURE SYSTEMS WILL MOVE NORTHEASTWARD ALONG THE
FRONT. THE LAST IN THE SERIES OF LOWS IS FORECAST TO BEGIN LIFTING
NORTHEAST OF THE AREA WEDNESDAY NIGHT. DRY AND COOL HIGH PRESSURE
WILL FOLLOW FOR THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH TODAY/...
THE FRONT WILL BE STALLED NEAR THE COAST TODAY. THE FRONT WILL BE
PARALLEL TO THE SOUTHWEST FLOW ALOFT. A MID-LEVEL SHORTWAVE TROUGH
OVER THE GULF OF MEXICO EARLY THIS MORNING SHOULD RESULT IN A
MOISTURE INCREASE LATER THIS AFTERNOON. THE RAP SHOWS THIS
INCREASE. THERE MAY BE ENOUGH MOISTURE FOR RAIN. FORECASTED CHANCE
POPS WITH THE GREATEST CHANCE IN THE SOUTHEAST PART. USED THE
GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
EXPECT A CONTINUED SERIES OF LOW PRESSURE SYSTEMS MOVING
NORTHEASTWARD ALONG THE STALLED FRONTAL ZONE. THE MODELS
GENERALLY SHOW DEEPER MOISTURE JUST EAST OF THE FORECAST AREA WITH
THE FARTHEST EXTENT WESTWARD WEDNESDAY AND WEDNESDAY NIGHT
ASSOCIATED WITH THE MAIN MID-LEVEL SHORTWAVE TROUGH. THE
NAM...GFS...AND ECMWF APPEAR TO INDICATE ENOUGH MOISTURE IN THE
EAST PART FOR LIKELY POPS WEDNESDAY OR WEDNESDAY NIGHT. THE
GUIDANCE CONSENSUS SUPPORTED POPS OF LIKELY EAST TO CHANCE WEST.
THERE WILL BE A TIGHT MOISTURE GRADIENT FROM WEST TO EAST AND THIS
MAKES FORECAST CONFIDENCE LOW. THE GUIDANCE TEMPERATURES APPEAR
TOO WARM WEDNESDAY BECAUSE OF A WEDGE PATTERN. OTHERWISE...USED
THE CONSENSUS.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
THE LATEST GFS AND ECMWF AGREE SHOWING DRY RIDGING BECOMING
DOMINATE THURSDAY AND CONTINUING OVER THE AREA FRIDAY. THE MODELS
SHOW A MOISTURE INCREASE SATURDAY WITH A FRONT IN THE AREA SUNDAY.
THE GFS ENSEMBLE MEANS SUPPORT LOW POPS AT THIS TIME. EXPECT
TEMPERATURES ABOVE NORMAL PRIOR TO FRONTAL PASSAGE.
&&
.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
COLD FRONT REMAINS JUST WEST OF THE TERMINALS BUT WILL PUSH EAST
DURING THE 06Z-12Z TIME FRAME. VFR CONDITIONS TO START THE
FORECAST BUT EXPECT MVFR CIGS TO ACCOMPANY THE FRONTAL ZONE AS IT
MOVES EAST ACROSS THE AREA. MVFR CIGS EXPECTED 09Z-15Z WITH
POSSIBLE IFR CIGS AGS/DNL. LIGHT WEST TO SOUTHWEST WINDS THROUGH
15Z THEN PICKING UP FROM THE WEST AROUND 5 TO 8 KNOTS. COLD FRONT
TO STALL EAST OF THE AREA TODAY AND EXPECT MID AND HIGH CLOUDS TO
CONTINUE TO PROVIDE A VFR CLOUD DECK THROUGH THE END OF THE
FORECAST PERIOD.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE IN SHOWERS
ASSOCIATED WITH A WAVE OF LOW PRESSURE LIFTING NORTHWARD TUESDAY
NIGHT THROUGH WEDNESDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1152 PM CST MON DEC 10 2012
.DISCUSSION...
302 PM CST
SURFACE TROUGH EXTENDS WEST-EAST FROM ABOUT KRPJ TO KMDW AND OVER
INTO BERRIEN COUNTY MICHIGAN PER 20Z ANALYSIS. SCATTERED SNOW
SHOWERS HAVE BEEN CONFINED TO THE VICINITY OF THE TROUGH AXIS FOR
THE MOST PART THIS AFTERNOON...WITH SOMEWHAT HEAVIER SNOW SHOWERS
OVER LAKE MICHIGAN EXTENDING INTO FAR NORTHEAST PORTER AND LAPORTE
COUNTIES. WHILE A FEW OF THE SNOW SHOWERS OVER NORTHERN IL HAVE
PRODUCED RADAR RETURNS NEAR 35 DBZ AT TIMES...IT APPEARS THE
POTENTIAL FOR PICKING UP ANY MEASURABLE SNOW OF ANY SIGNIFICANCE IS
QUITE LOW. WITH THE BOUNDARY SAFELY SOUTH OF BOTH RFD AND ORD...AND
BOTH LOCATIONS ONLY PICKING UP TRACE AMOUNTS OF SNOW TODAY...IT
LOOKS AS IF THE STREAK OF DAYS WITHOUT MEASURABLE SNOW WILL CONTINUE
PAST 280 DAYS! THUS UNLESS SOMETHING ODD OCCURS...CHICAGO WILL VERY
LIKELY SET A NEW RECORD OF 281 CONSECUTIVE DAYS WITHOUT MEASURABLE
SNOW.
AS COLDER AIR CONTINUES TO SPREAD ACROSS LAKE MICHIGAN THIS
EVENING...LAKE EFFECT SNOW SHOWERS SHOULD BECOME MORE ORGANIZED WITH
NORTH-SOUTH BANDING DEVELOPING OVER MID AND EASTERN LAKE MICHIGAN.
LATEST HIGH-RES GUIDANCE INCLUDING WRF-NMM...WRF-NAM AND RAP RUNS
ALL SUGGEST THAT PORTIONS OF PORTER COUNTY MAY SEE A BRIEF PERIOD OF
LAKE EFFECT INTO THIS EVENING...BEFORE BOUNDARY LAYER WINDS BACK
MORE WESTERLY AFTER MIDNIGHT AND PUSH THE LOW LEVEL CONVERGENT FOCUS
EAST TOWARD THE MICHIGAN SHORE. CURRENT LAKE-ENHANCED BAND OVER FAR
SOUTHERN LAKE MICHIGAN HAS PRODUCED VISIBILITY AS LOW AS 1/2SM-1/4SM
AT SOUTH BEND IN THE LAST HOUR OR SO...AN INDICATION THAT SOME
RELATIVELY HEAVY SNOW MAY FALL FOR AT LEAST A SHORT TIME. 850 HPA
TEMPS COOLING TO AROUND -9C...AND RESULTING LAKE-850 HPA DELTA T
VALUES AROUND 16/17C WOULD POTENTIALLY SUPPORT 1-3/2-4 INCHES IF IT
WERE ABLE TO FOCUS ON A LOCALE FOR A FEW HOURS. GIVEN TRANSIENT
NATURE AND RELATIVELY SHORT DURATION EXPECTED FOR BAND TO REALLY
FOCUS ON NORTHEAST PORTER COUNTY...WOULD THINK THAT THE LOWER END OF
THIS RANGE IS MORE LIKELY THROUGH MIDNIGHT TONIGHT. AGAIN...SNOW
SHOULD END FOR PORTER COUNTY BY 06-09Z TONIGHT AS THE FOCUS DRIFTS
EAST OF THE AREA.
OTHERWISE...CONSIDERABLE AREA OF STRATUS/STRATOCU NOTED PER
AFTERNOON VISIBLE SATELLITE IMAGERY WITHIN LOW LEVEL COLD ADVECTION
BENEATH BROAD UPPER TROUGH WITH SERIES OF WEAK VORTS TRANSITING THE
REGION THROUGH TUESDAY. CLOUDS/FEW FLURRIES THIS AFTERNOON SHOULD
GRADUALLY TRANSITION TO PARTLY CLOUDY CONDITIONS FROM THE WEST LATE
TONIGHT/EARLY TUESDAY...WITH LARGE SCALE UPPER TROUGH AXIS FINALLY
MOVING EAST OF THE AREA TUESDAY NIGHT. BROAD...FLAT UPPER RIDGING
THEN BUILDS ACROSS THE GREAT LAKES AND SOUTHEAST WEDNESDAY/THURSDAY
WITH A PERIOD OF DRY AND SLOWLY MODERATING WEATHER.
NEXT WEATHER MAKER TO MONITOR IS AN UPPER TROUGH CURRENTLY
PROPAGATING ACROSS THE GULF OF ALASKA. MEDIUM RANGE GUIDANCE REMAINS
CONSISTENT IN DIGGING THIS SYSTEM SOUTH ALONG THE WEST COAST THROUGH
MID-WEEK...DEVELOPING INTO A CLOSED LOW ALONG THE CALIFORNIA COAST
BY LATE THURSDAY. THIS SYSTEM IS THEN PROGGED TO MOVE OUT ACROSS THE
PLAINS FRIDAY/FRIDAY NIGHT AND ACROSS OUR REGION SATURDAY. THERE
REMAINS SOME MODEL SPREAD WITH THE TRACK OF THE LOW ACROSS
MISSOURI/ILLINOIS BY SATURDAY...BUT THATS TO BE EXPECTED AT THIS
DISTANCE ESPECIALLY WITH LOWS EJECTING FROM THE SOUTHWESTERN STATES.
BOTH THE ECMWF AND GFS RUNS ARE A LITTLE FARTHER SOUTH THAN THOSE
FROM 24 HOURS AGO...THOUGH STILL APPEARS TO BE MAINLY A WARM/RAIN
EVENT FOR THE FORECAST AREA. CONTINUED TO FAVOR THE CONSISTENT ECMWF
SOLUTION FOR TIMING OF PRECIP/PRECIP TYPE FRIDAY NIGHT THROUGH
SATURDAY.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* LOWER END VFR CIGS TO PERSIST THROUGH THE EARLY MORNING HOURS.
* SOME LIGHT SNOW/FLURRIES POSSIBLY OVERNIGHT WITH MINIMAL VSBY
REDUCTIONS...AND POSSIBLY CIG REDUCTION TO MVFR.
* SOUTHWEST WINDS WILL GUST TO AROUND 20KT TUESDAY LATE MORNING
INTO THE AFTERNOON.
KREIN
//DISCUSSION...UPDATED 06Z...
A LINGERING LOWER END VFR ST/SC DECK HAS BEEN SLOW TO CLEAR THE
REGION UNDER CYCLONIC FLOW ALOFT. A WEAK SHORT WAVE CROSSING NRN
IL HAS HELPED GENERATE SOME -SHSN...WHICH HAVE BEEN MOST PREVALENT
OVER NCNTRL IL...WITH ANOTHER PATCH MOVING THROUGH NWRN IN...PER
LATEST RADAR TRENDS. EXPECT THAT THERE IS STILL SOME POTENTIAL FOR
SOME -SN/-SHSN UNTIL ARND 09Z WHEN THE SHORTWAVE WILL FINALLY MOVE
OFF TO THE EAST AND WEAK RIDGING WILL DEVELOP ALOFT. LATEST
SATELLITE IMAGERY SHOWS A BACK EDGE TO THE CLOUD DECK APPROACHING
THE MS RIVER AND SHOULD STEADILY PUSH EWD...LEADING TO MOSTLY
CLEAR SKIES SHORTLY BEFORE DAYBREAK.
WITH A LOW PRESSURE SYSTEM TRACKING EWD THROUGH SCNTRL CANADA AND
HIGH PRESSURE SETTING OVER THE OHIO VALLEY...WINDS WILL BECOME
SWLY THROUGH THE MORNING. WITH AMPLE SUNSHINE AIDING DEEP LAYER
MIXING AND A STRENGTHENING PRESSURE GRADIENT...THERE SHOULD BE
FREQUENT GUSTS TO ARND 20KT FROM LATE MORNING THROUGH SUNSET.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM CONFIDENCE IN CIGS TONIGHT AND TIMING OF CLEARING.
* LOW TO MEDIUM CONFIDENCE IN -SN OVERNIGHT.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS
KREIN
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY THROUGH FRIDAY...VFR.
SATURDAY...RAIN LIKELY. IFR PROBABLE.
SUNDAY...MVFR CIGS LIKELY.
IZZI
&&
.MARINE...
313 PM CST
N AND NE WINDS WILL DIMINISH TONIGHT AS LOW PRESSURE IN SW QUEBEC
MOVES E TO THE GULF OF SAINT LAWRENCE OVERNIGHT ALLOWING HIGH
PRESSURE OVER ONTARIO TO DROP SSE TO THE LOWER GREAT LAKES. S AND
SW WINDS WILL BE ON THE INCREASE TUE AS THE HIGH MERGES WITH
ANOTHER HIGH PRESSURE RIDGE OVER THE SOUTHERN PLAINS...OZARKS AND
LOWER OH VALLEY. WINDS SLACKEN AGAIN OVERNIGHT TUE BEFORE
FRESHENING AGAIN DURING WED AS LOW PRESSURE IN THE NORTHERN HIGH
PLAINS ELONGATES ACROSS THE UPPER MIDWEST INTO ONTARIO BY THU.
WINDS MAY REACH GALE FORCE BY WED NIGHT ON NORTHERN LAKE MI...AND
PERSIST INTO THU. THE LOW PRESSURE TROUGH DROPS S ACROSS THE GREAT
LAKES FRI WHILE LOW PRESSURE DEEPENS AS IT MOVES E FROM THE
CENTRAL ROCKIES TO THE CENTRAL PLAINS FRI AND FRI NIGHT. THIS LOW
TURNS NE TO THE MID MS VALLEY SAT AND MOVES INTO THE UPPER GREAT
LAKES SAT NIGHT.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 AM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
125 AM EST MON DEC 10 2012
.AVIATION... /06 UTC TAFS/
PRIMARY FOCUS ON DWINDLING LES EVENT. BACKED CLOUD BEARING LAYER
FLOW HAS SHUNTED PRIMARY BAND WELL NORTH OF KSBN ATTM. LESSER
MULTIPLE BANDS CONT TO SW...WITH BACK EDGE INTO NCNLT LA PORTE CO.
SHARP DECRS IN MSTR DEPTH/DWINDLING DENDRITIC GROWTH LAYER ALONG
WITH INCSRG DRY AIR ADVECTION WITHIN 925-850MB LYR TO FURTHER WEAKEN
REMNG LES BANDS THRU 08 UTC. MAINTAIN TEMPO IFR AT KSBN TIL THEN
WITH BRIEF THOUGH SIG HORIZONTAL VSBY LWRG IN 25-30 DBZ CELLS. WITH
DCRSD MSTR AND SUBSIDENCE /MID LVL HGHT RISES/ ANTICIPATE END TO
SPOTTY IFR CIGS ACRS NCNTL/NERN IN AS WELL BYND 08 UTC. INCRSD
SSWRLY FLOW BY MIDDAY INADVOF CLIPPER SYSTEM...THOUGH ANY PRECIP
ASSOCD SHOULD TUE NIGHT SHOULD HOLD N OF RGN.
&&
.UPDATE...
LAKE EFFECT SNOW SHOWERS WILL CONTINUE TO BE THE PRIMARY SHORT
TERM CONCERN. SFC TROUGH WHICH BROUGHT A PERIOD OF SNOW AND EVEN
SOME LIGHT RAIN TO NORTHERN SECTIONS OF FORECAST AREAS NOW APPEARS
TO EXTEND FROM A LINE FROM SOUTHERN LA PORE COUNTY EXTENDING
EASTWARD ALONG THE ROUTE 30 CORRIDOR. LIGHT SNOW PERSISTS ALONG
THIS CONVERGENCE AXIS WITH SNOWFALL AMOUNTS GENERALLY LESS THAN A
HALF INCH OBSERVED AS THIS AREA HAS DROPPED SOUTHWARD. LAKE EFFECT
SNOW SHOWERS HAVE INCREASED SIGNIFICANTLY OVER PAST TWO HOURS
ACROSS FAR EASTERN LAKE MICHIGAN WHERE THERMALLY INDUCED SFC
CONVERGENCE APPEARS TO BE AIDING IN FOCUSING LAKE EFFECT SNOW
SHOWERS. LAKE EFFECT PARAMETERS STILL APPEAR TO BE QUITE FAVORABLE
FOR A SHORT PERIOD OF MORE SIGNIFICANT LAKE EFFECT SNOW SHOWERS
ESPECIALLY IN THE 03Z-08Z TIMEFRAME...WHEN INVERSION HEIGHTS RISE
TO NEAR 7500 FT...AND LAKE INDUCED EQUILIBRIUM LEVELS REACH NEAR
13K FT. ORIENTATION OF THERMALLY INDUCED SFC TROUGH WOULD SUGGEST
THAT BERRIEN/WESTERN CASS COUNTY INLINE TO SEE MORE SIGNIFICANT
LAKE EFFECT SNOW SHOWERS...AND POSSIBLY EXTENDING INTO NORTH
CENTRAL/NORTHEAST PORTIONS OF LA PORTE COUNTY.
SECONDARY BAND ALSO APPEARS TO BE DEVELOPING WEST OF MICHIGAN CITY
WHICH APPEARS TO BE AIDED BY LARGER SCALE LOW LEVEL CONVERGENCE
FROM REMNANTS OF SLOW MOVING SFC TROUGH. LONGEVITY OF A FAVORABLE
WIND FIELD APPEARS MORE QUESTIONABLE WITH THIS BAND HOWEVER WITH
STRONGER CONVERGENCE LIKELY REMAINING ANCHORED CLOSER TO THE
EASTERN SHORELINE. GIVEN LINGERING UNCERTAINTIES AS TO HOW BANDING
WILL UNFOLD THE REMAINDER OF THE EVENING...HAVE MAINTAINED A
BROADBRUSH 1 TO 3 INCH MENTION IN FORECAST AND WILL HOLD OFF ON
ANY HEADLINES AT THIS TIME...ALTHOUGH IF HEADLINES ARE NEEDED IT
APPEARS AS THOUGH BERRIEN COUNTY WOULD HAVE A GREATER RISK AT
REACHING LOCALIZED ADVISORY LEVEL AMOUNTS. IT STILL APPEARS AS
THOUGH THERMAL CONVERGENCE SHOULD BEGIN TO BREAK DOWN AFTER
09Z...AS LARGE SCALE SYNOPTIC WINDS BEGIN TO FAVOR MORE WESTERLY
DIRECTIONS ALSO ACTING TO LIMIT FETCH AND LAKE SUPERIOR CONNECTION.
&&
.PREV DISCUSSION... /ISSUED 247 PM EST MON DEC 10 2012/
SHORT TERM...
DIFFICULT PD EARLY ON GIVEN SCOPE OF DVLPG LK RESPONSE. SFC TROUGH
ACRS NRN CONTS TO DROP SWD AND EMBOLDENING A BROADER RESPONSE
UNDERNEATH BALLOONING MID LVL MSTR PLUME. BRIEF PD OF FZDZ AND
PERHAPS SLEET AT ONSET BUT QUICKLY CHANGING OVR TO SHSN N-S TIMED
W/ARRIVAL OF LK MSTR ENTRAINMENT PLUME AND DEEPENING CAA WEDGE.
PRIMARY PROB THIS EVENING IS TEA KETTLE LK SETUP AND DENOTED QUITE
WELL IN RUC13 AND OTHER HIGHRES GUIDANCE. LK SP CONNECTION NOTED
THIS AFTN WITHIN FVRBLY VEERED LONG AXIS CYCLONIC FETCH AS SEEN IN
VIS IMAGERY AND SUSPECT LK CONVERGENCE ZONE WILL ABRUPTLY BLOSSOM
AFT SUNSET IN TANDEM W/MAXIMIZING LL THERMAL TROUGH OF WHICH MAY
LEAD TO A BRIEF PD OF SIG LK EFFECT SNOWFALL CNTRD THROUGH EXTREME
SW BERRIEN...NRN LAPORTE AND WRN ST JOE COUNTIES. TEMPTED TO
CONSIDER AN ADVISORY BUT GIVEN UPSTREAM LK DVLPMNTS HAVE YET TO
PLAY THEIR CARD...CONFIDENCE LACKING. WILL CONT TO MONITOR AND
PASS CONCERNS ONWARD.
OTRWS LG SCALE SFC RIDGE WILL BUILD ALG THE APPALACHIAN SPINE
THROUGH THE END OF THE PD AS WK SECONDARY SYS DIPS THROUGH SRN
ONTARIO. LL FLW BACKS ABRUPTLY LT TONIGHT TO WRLY W/DWINDLING LK
EFFECT LIFTING OUT BFR BACKING FURTHER TO SWRLY ON TUE. THIS WILL
YIELD SW-NE CLRG W/SOME INSOLATION HELPING TO BOOST TEMPS A BIT
WARMER THAN TDA.
LONG TERM...WEDNESDAY THROUGH MONDAY.
ENERGY CURRENTLY IN THE GULF OF ALASKA WILL DIG ALONG THE PACIFIC
COAST THROUGH THE UPCOMING WEEK...REACHING CALIFORNIA BY THURSDAY.
THIS WILL ALLOW FOR INCREASING HGTS WITH A SEMI ZONAL FLOW TO SET UP
THROUGH FRIDAY. TEMPS ARE EXPECTED TO MODERATE TO ABOVE NORMAL
LEVELS IN THE 40S.
LEE SIDE CYCLOGENESIS WILL TAKE PLACE STARTING LATE FRIDAY WITH THE
SYSTEM EJECTING TOWARDS THE GREAT LAKES. MODELS VARYING SOMEWHAT ON
TIMING AND OVERALL TRACK...BUT SEEM TO POINT TOWARDS THE FORECAST
AREA BEING ON THE WARM SIDE ONCE AGAIN...YIELDING RAIN CHANCES FOR
THE WEEKEND FOLLOWED BY A MIXTURE OF RAIN/SNOW IN ITS WAKE. PREV
GRIDS HAD DECENT HANDLE ON TRENDS. ONLY CHANGES MADE WAS TO BREAK UP
WITH SOMEWHAT MORE DETAIL TO TRY TO ADD SOME TIMING TO BETTER
CHANCES OF PRECIP. QUICK SHOT OF COLD AIR WILL ARRIVE BEHIND THE
SYSTEM...BUT NOTHING SUBSTANTIALLY COLDER WITH A RETURN TO NEAR OR
SLIGHTLY BELOW NORMAL READINGS.
ENERGIZED PATTERN WILL CONTINUE OUTSIDE THE LONG TERM PERIOD WITH
NEXT SYSTEM ALREADY TAKING SHAPE OVER TEXAS BY MONDAY NIGHT. ECMWF
OVER THE PAST SEVERAL RUNS HAS HINTED THAT THIS COULD BRING A DECENT
SHOT OF ACCUMULATING SNOWFALL TO THE REGION BOTH IN ADVANCE OF THE
SYSTEM AND WITH WHAT COULD BE A PERSISTENT DEFORMATION ZONE AS THE
LOW CUTS OFF SOMEWHERE IN THE EASTERN GREAT LAKES. PLENTY OF TIME TO
WATCH AT THIS POINT CONSIDERING STILL A WAYS TO GO.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 4 AM EST TUESDAY FOR LMZ043-046.
&&
$$
SHORT TERM...T
LONG TERM...FISHER
UPDATE...MARSILI
AVIATION...MURPHY
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1020 AM MST TUE DEC 11 2012
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 216 AM MST TUE DEC 11 2012
04Z WATER VAPOR IMAGERY/RUC ANALYSIS INDICATED BROAD TROUGHING
ACROSS MUCH OF THE CONUS. PV ANALYSIS INDICATED SHORT WAVE TROUGH
MOVING INTO NORTHERN COLORADO...WITH AREA OF LIGHT SNOW OCCURRING TO
THE SOUTHWEST OF MAIN ANOMALY. AT THE SFC...HIGH PRESSURE WAS
CENTERED ACROSS THE AREA WITH AREA OF VERY LOW DEWPOINTS NOTED
ACROSS SOUTHWEST KANSAS...WITH HIGHER DEWPOINTS MOVING INTO THE AREA
FROM THE NORTH. 00Z RAOBS UPSTREAM OF THE AREA INDICATED MUCH
HIGHER LAPSE RATES THAN 24 HOURS AGO...AND WHILE LAPSE RATES WERE
NOT DRY ADIABATIC THEY WOULD SUPPORT CONDITIONAL INSTABILITY OR
NEUTRAL CONDITIONS SHOULD SATURATION OCCUR.
MAIN FORECAST CONCERNS WILL BE LIGHT SNOW POTENTIAL THROUGH THE
EARLY MORNING HOURS FOLLOWED BUY RISING TEMPS AND FIRE WX POTENTIAL
THROUGH THURSDAY.
TODAY...INITIAL CONCERN WILL BE AREA OF LIGHT SNOW TO THE WEST OF THE
AREA OCCURRING AHEAD OF WEAK PV ANOMALY. RUC SEEMS TO BE ONLY NEAR
TERM MODEL THAT HAS CAUGHT ON TO THIS...ALTHOUGH PRECIP AREA LOOKS
TOO LARGE FOR WHAT IS OCCURRING. FROM WHAT I CAN TELL FROM THE POINT
SOUNDINGS...FORCED ASCENT REALLY CONCENTRATED IN THE LOW LEVELS
AROUND THE DGZ WHICH IS LOCATED AROUND H7. GIVEN THE OVERALL PATTERN
THINK PRECIP THREAT WILL CONTINUE UNTIL H8-H7 FLOW BECOMES MORE
NORTHWESTERLY LEADING TO WEAK CAA AFTER 09Z. THERE IS SOME
INSTABILITY TO WORK WITH...BUT BASED ON LATEST RADAR TRENDS SEEMS
DOUBTFUL THAT SIG SNOW AMOUNTS WOULD OCCUR IN CWA. OTHERWISE...THINK
PRECIP CHANCES WILL END QUICKLY WITH SKIES CLEARING THROUGH THE DAY
AS LARGE SCALE SUBSIDENCE MOVES OVER THE AREA BEHIND TROUGH.
TONIGHT-TOMORROW...SHORT WAVE RIDGE WILL AMPLIFY OVER THE AREA
DURING THE PERIOD BRINGING DRY CONDITIONS AND A FEW HIGH CLOUDS.
OVERALL DO NOT THINK CLOUDS WILL HAVE A BIG IMPACT ON
TEMPS...ALTHOUGH AM A LITTLE CONCERNED THAT STRONG H3 FLOW
PERPENDICULAR TO ROCKIES MAY CREATE AN ENHANCED AREA OF CIRRUS DURING
THE AFTERNOON. DESPITE THE LOW LEVEL WESTERLY FLOW...THE POTENTIAL
FOR HIGH CLOUD COVER AND LATEST ROUND OF OPERATIONAL DATA HAS
TEMPERED MY CONFIDENCE IN A SIG WARM UP SOMEWHAT AND HAVE LOWERED
HIGHS A FEW DEGREES ACROSS EASTERN CWA. FOR THE AREAS THAT DO MIX
OUT/WARM STRONGLY UPPER 50S AND AFTERNOON HUMIDITIES AROUND 15
PERCENT LIKELY. WILL HAVE NEAR CRITICAL FIRE WX CONDITIONS IN THIS
AREA...BUT NOT A LOT OF SUPPORT FOR STRONG WINDS EVEN WITH
DEVELOPING LEE TROUGH. CANNOT RULE OUT RED FLAG CONDITIONS
DEVELOPING...BUT CONFIDENCE TOO LOW IN WINDS MATERIALIZING TO ISSUE
WATCH ATTM.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 216 AM MST TUE DEC 11 2012
WED NIGHT-THUR NIGHT...SHORT WAVE RIDGE WILL BE PRIMARY INFLUENCE OF
WEATHER ACROSS THE CWA AS FLOW ALOFT BECOMES MORE AMPLIFIED IN
RESPONSE TO WEST COAST TROUGH. GIVEN THE PATTERN AND VERTICAL
MOISTURE/STABILITY PROFILES...SEE NO REASON WHY DRY CONDITIONS WILL
NOT CONTINUE THROUGH THE PERIOD. SHOULD SEE WARMING TREND THROUGH
THE PERIOD...ESPECIALLY IN OVERNIGHT LOWS. GENERALLY KEPT WELL ABOVE
NORMAL MAX T FORECAST GOING...ALTHOUGH AM A LITTLE CONCERNED THAT
LATEST GUIDANCE INDICATING WEAK FRONTAL ZONE MOVING THROUGH AREA
RESULTING IN LIGHT...BACKED WINDS THURSDAY.
FRIDAY-MONDAY...
MAIN FOCUS CONTINUES TO BE ON UPPER LOW WHICH IS EXPECTED TO DEVELOP
OVER THE SW US AND POSSIBLY IMPACT OUR CWA FRIDAY AFTERNOON THROUGH
EARLY SATURDAY MORNING. AS HAS BEEN THE CASE THE LAST FEW DAYS THE
GEFS AND ECMWF CONTINUE TO SHOW LARGE SPREAD IN SOLUTIONS RUN TO RUN
FOR THIS SYSTEM...WITH THE OPERATIONAL GFS SLIGHTLY MORE CONSISTENT.
THIS TROUGH IS STILL SOUTH OF THE ALEUTIAN ISLANDS OVER THE NORTHERN
PACIFIC....AND UNTIL IT IS BETTER SAMPLED IT IS HARD FOR ME TO MAKE
LARGE CHANGES TO THIS FORECAST PERIOD. CONFIDENCE IS STILL HIGHEST
ACROSS OUR EASTERN CWA...THOUGH I HAVE EXPANDED CHANCE POPS FURTHER
WEST TO ACCOUNT FOR LATEST ECMWF TRENDS. OTHER COMPLICATING FACTOR
IS WAA ADVERTISED BY ECMWF AND GFS WHICH COULD DELAY SNOW CHANGE
OVER. CONSIDERING THE ABSENCE OF STRONG CAA BEHIND THIS SYSTEM...AND
RELIANCE ON EVAPORATIVE PROCESSES FOR CHANGE OVER I AM NOT CONFIDENT
THAT WE WOULD SEE LARGE SNOW ACCUMULATIONS EVEN WITH THE MOST
FAVORABLE TRACKS. I BUMPED UP THE LOW TEMP FORECAST TO LOW 30S
FRIDAY NIGHT AND THIS STILL MIGHT BE TOO COOL IF WE SEE THICK CLOUD
COVER.
SHORTWAVE RIDGING SHOULD KEEP CONDITIONS DRY SATURDAY AND SUNDAY. BY
MONDAY GFS/ECMWF ARE BOTH INDICATING ANOTHER TROUGH IMPACTING THE
HIGH/CENTRAL PLAINS...THOUGH THERE ARE SIGNIFICANT DIFFERENCES IN
EVOLUTION. I DECIDED TO KEEP SLIGHT CHANCE POPS IN PLACE MONDAY AS A
STARTING POINT...SINCE RAIN OR SNOW CANT BE RULED OUT WITH
ADVERTISED PATTERN.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1016 AM MST TUE DEC 11 2012
VFR CONDITIONS EXPECTED AT BOTH KGLD AND KMCK THROUGH THE TAF
PERIOD. SURFACE TROUGH OVER EASTERN COLORADO WILL KEEP WINDS
MAINLY OUT OF THE SOUTHWEST. A FEW HIGH CLOUDS WILL SPILL OVER THE
ROCKIES.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JRM
LONG TERM...JRM/DR
AVIATION...024
AREA FORECAST DISCUSSION
NWS GOODLAND KS
439 AM MST TUE DEC 11 2012
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 216 AM MST TUE DEC 11 2012
04Z WATER VAPOR IMAGERY/RUC ANALYSIS INDICATED BROAD TROUGHING
ACROSS MUCH OF THE CONUS. PV ANALYSIS INDICATED SHORT WAVE TROUGH
MOVING INTO NORTHERN COLORADO...WITH AREA OF LIGHT SNOW OCCURRING TO
THE SOUTHWEST OF MAIN ANOMALY. AT THE SFC...HIGH PRESSURE WAS
CENTERED ACROSS THE AREA WITH AREA OF VERY LOW DEWPOINTS NOTED
ACROSS SOUTHWEST KANSAS...WITH HIGHER DEWPOINTS MOVING INTO THE AREA
FROM THE NORTH. 00Z RAOBS UPSTREAM OF THE AREA INDICATED MUCH
HIGHER LAPSE RATES THAN 24 HOURS AGO...AND WHILE LAPSE RATES WERE
NOT DRY ADIABATIC THEY WOULD SUPPORT CONDITIONAL INSTABILITY OR
NEUTRAL CONDITIONS SHOULD SATURATION OCCUR.
MAIN FORECAST CONCERNS WILL BE LIGHT SNOW POTENTIAL THROUGH THE
EARLY MORNING HOURS FOLLOWED BUY RISING TEMPS AND FIRE WX POTENTIAL
THROUGH THURSDAY.
TODAY...INITIAL CONCERN WILL BE AREA OF LIGHT SNOW TO THE WEST OF THE
AREA OCCURRING AHEAD OF WEAK PV ANOMALY. RUC SEEMS TO BE ONLY NEAR
TERM MODEL THAT HAS CAUGHT ON TO THIS...ALTHOUGH PRECIP AREA LOOKS
TOO LARGE FOR WHAT IS OCCURRING. FROM WHAT I CAN TELL FROM THE POINT
SOUNDINGS...FORCED ASCENT REALLY CONCENTRATED IN THE LOW LEVELS
AROUND THE DGZ WHICH IS LOCATED AROUND H7. GIVEN THE OVERALL PATTERN
THINK PRECIP THREAT WILL CONTINUE UNTIL H8-H7 FLOW BECOMES MORE
NORTHWESTERLY LEADING TO WEAK CAA AFTER 09Z. THERE IS SOME
INSTABILITY TO WORK WITH...BUT BASED ON LATEST RADAR TRENDS SEEMS
DOUBTFUL THAT SIG SNOW AMOUNTS WOULD OCCUR IN CWA. OTHERWISE...THINK
PRECIP CHANCES WILL END QUICKLY WITH SKIES CLEARING THROUGH THE DAY
AS LARGE SCALE SUBSIDENCE MOVES OVER THE AREA BEHIND TROUGH.
TONIGHT-TOMORROW...SHORT WAVE RIDGE WILL AMPLIFY OVER THE AREA
DURING THE PERIOD BRINGING DRY CONDITIONS AND A FEW HIGH CLOUDS.
OVERALL DO NOT THINK CLOUDS WILL HAVE A BIG IMPACT ON
TEMPS...ALTHOUGH AM A LITTLE CONCERNED THAT STRONG H3 FLOW
PERPENDICULAR TO ROCKIES MAY CREATE AN ENHANCED AREA OF CIRRUS DURING
THE AFTERNOON. DESPITE THE LOW LEVEL WESTERLY FLOW...THE POTENTIAL
FOR HIGH CLOUD COVER AND LATEST ROUND OF OPERATIONAL DATA HAS
TEMPERED MY CONFIDENCE IN A SIG WARM UP SOMEWHAT AND HAVE LOWERED
HIGHS A FEW DEGREES ACROSS EASTERN CWA. FOR THE AREAS THAT DO MIX
OUT/WARM STRONGLY UPPER 50S AND AFTERNOON HUMIDITIES AROUND 15
PERCENT LIKELY. WILL HAVE NEAR CRITICAL FIRE WX CONDITIONS IN THIS
AREA...BUT NOT A LOT OF SUPPORT FOR STRONG WINDS EVEN WITH
DEVELOPING LEE TROUGH. CANNOT RULE OUT RED FLAG CONDITIONS
DEVELOPING...BUT CONFIDENCE TOO LOW IN WINDS MATERIALIZING TO ISSUE
WATCH ATTM.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 216 AM MST TUE DEC 11 2012
WED NIGHT-THUR NIGHT...SHORT WAVE RIDGE WILL BE PRIMARY INFLUENCE OF
WEATHER ACROSS THE CWA AS FLOW ALOFT BECOMES MORE AMPLIFIED IN
RESPONSE TO WEST COAST TROUGH. GIVEN THE PATTERN AND VERTICAL
MOISTURE/STABILITY PROFILES...SEE NO REASON WHY DRY CONDITIONS WILL
NOT CONTINUE THROUGH THE PERIOD. SHOULD SEE WARMING TREND THROUGH
THE PERIOD...ESPECIALLY IN OVERNIGHT LOWS. GENERALLY KEPT WELL ABOVE
NORMAL MAX T FORECAST GOING...ALTHOUGH AM A LITTLE CONCERNED THAT
LATEST GUIDANCE INDICATING WEAK FRONTAL ZONE MOVING THROUGH AREA
RESULTING IN LIGHT...BACKED WINDS THURSDAY.
FRIDAY-MONDAY...
MAIN FOCUS CONTINUES TO BE ON UPPER LOW WHICH IS EXPECTED TO DEVELOP
OVER THE SW US AND POSSIBLY IMPACT OUR CWA FRIDAY AFTERNOON THROUGH
EARLY SATURDAY MORNING. AS HAS BEEN THE CASE THE LAST FEW DAYS THE
GEFS AND ECMWF CONTINUE TO SHOW LARGE SPREAD IN SOLUTIONS RUN TO RUN
FOR THIS SYSTEM...WITH THE OPERATIONAL GFS SLIGHTLY MORE CONSISTENT.
THIS TROUGH IS STILL SOUTH OF THE ALEUTIAN ISLANDS OVER THE NORTHERN
PACIFIC....AND UNTIL IT IS BETTER SAMPLED IT IS HARD FOR ME TO MAKE
LARGE CHANGES TO THIS FORECAST PERIOD. CONFIDENCE IS STILL HIGHEST
ACROSS OUR EASTERN CWA...THOUGH I HAVE EXPANDED CHANCE POPS FURTHER
WEST TO ACCOUNT FOR LATEST ECMWF TRENDS. OTHER COMPLICATING FACTOR
IS WAA ADVERTISED BY ECMWF AND GFS WHICH COULD DELAY SNOW CHANGE
OVER. CONSIDERING THE ABSENCE OF STRONG CAA BEHIND THIS SYSTEM...AND
RELIANCE ON EVAPORATIVE PROCESSES FOR CHANGE OVER I AM NOT CONFIDENT
THAT WE WOULD SEE LARGE SNOW ACCUMULATIONS EVEN WITH THE MOST
FAVORABLE TRACKS. I BUMPED UP THE LOW TEMP FORECAST TO LOW 30S
FRIDAY NIGHT AND THIS STILL MIGHT BE TOO COOL IF WE SEE THICK CLOUD
COVER.
SHORTWAVE RIDGING SHOULD KEEP CONDITIONS DRY SATURDAY AND SUNDAY. BY
MONDAY GFS/ECMWF ARE BOTH INDICATING ANOTHER TROUGH IMPACTING THE
HIGH/CENTRAL PLAINS...THOUGH THERE ARE SIGNIFICANT DIFFERENCES IN
EVOLUTION. I DECIDED TO KEEP SLIGHT CHANCE POPS IN PLACE MONDAY AS A
STARTING POINT...SINCE RAIN OR SNOW CANT BE RULED OUT WITH
ADVERTISED PATTERN.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 435 AM MST TUE DEC 11 2012
VFR CONDITIONS WILL CONTINUE THROUGH THE PERIODS WITH WESTERLY
WINDS INCREASING TO AROUND 13 KTS THIS AFTERNOON BEFORE DECREASING
AROUND SUNSET.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JRM
LONG TERM...JRM/DR
AVIATION...JRM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
217 AM MST TUE DEC 11 2012
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 216 AM MST TUE DEC 11 2012
04Z WATER VAPOR IMAGERY/RUC ANALYSIS INDICATED BROAD TROUGHING
ACROSS MUCH OF THE CONUS. PV ANALYSIS INDICATED SHORT WAVE TROUGH
MOVING INTO NORTHERN COLORADO...WITH AREA OF LIGHT SNOW OCCURRING TO
THE SOUTHWEST OF MAIN ANOMALY. AT THE SFC...HIGH PRESSURE WAS
CENTERED ACROSS THE AREA WITH AREA OF VERY LOW DEWPOINTS NOTED
ACROSS SOUTHWEST KANSAS...WITH HIGHER DEWPOINTS MOVING INTO THE AREA
FROM THE NORTH. 00Z RAOBS UPSTREAM OF THE AREA INDICATED MUCH
HIGHER LAPSE RATES THAN 24 HOURS AGO...AND WHILE LAPSE RATES WERE
NOT DRY ADIABATIC THEY WOULD SUPPORT CONDITIONAL INSTABILITY OR
NEUTRAL CONDITIONS SHOULD SATURATION OCCUR.
MAIN FORECAST CONCERNS WILL BE LIGHT SNOW POTENTIAL THROUGH THE
EARLY MORNING HOURS FOLLOWED BUY RISING TEMPS AND FIRE WX POTENTIAL
THROUGH THURSDAY.
TODAY...INITIAL CONCERN WILL BE AREA OF LIGHT SNOW TO THE WEST OF THE
AREA OCCURRING AHEAD OF WEAK PV ANOMALY. RUC SEEMS TO BE ONLY NEAR
TERM MODEL THAT HAS CAUGHT ON TO THIS...ALTHOUGH PRECIP AREA LOOKS
TOO LARGE FOR WHAT IS OCCURRING. FROM WHAT I CAN TELL FROM THE POINT
SOUNDINGS...FORCED ASCENT REALLY CONCENTRATED IN THE LOW LEVELS
AROUND THE DGZ WHICH IS LOCATED AROUND H7. GIVEN THE OVERALL PATTERN
THINK PRECIP THREAT WILL CONTINUE UNTIL H8-H7 FLOW BECOMES MORE
NORTHWESTERLY LEADING TO WEAK CAA AFTER 09Z. THERE IS SOME
INSTABILITY TO WORK WITH...BUT BASED ON LATEST RADAR TRENDS SEEMS
DOUBTFUL THAT SIG SNOW AMOUNTS WOULD OCCUR IN CWA. OTHERWISE...THINK
PRECIP CHANCES WILL END QUICKLY WITH SKIES CLEARING THROUGH THE DAY
AS LARGE SCALE SUBSIDENCE MOVES OVER THE AREA BEHIND TROUGH.
TONIGHT-TOMORROW...SHORT WAVE RIDGE WILL AMPLIFY OVER THE AREA
DURING THE PERIOD BRINGING DRY CONDITIONS AND A FEW HIGH CLOUDS.
OVERALL DO NOT THINK CLOUDS WILL HAVE A BIG IMPACT ON
TEMPS...ALTHOUGH AM A LITTLE CONCERNED THAT STRONG H3 FLOW
PERPENDICULAR TO ROCKIES MAY CREATE AN ENHANCED AREA OF CIRRUS DURING
THE AFTERNOON. DESPITE THE LOW LEVEL WESTERLY FLOW...THE POTENTIAL
FOR HIGH CLOUD COVER AND LATEST ROUND OF OPERATIONAL DATA HAS
TEMPERED MY CONFIDENCE IN A SIG WARM UP SOMEWHAT AND HAVE LOWERED
HIGHS A FEW DEGREES ACROSS EASTERN CWA. FOR THE AREAS THAT DO MIX
OUT/WARM STRONGLY UPPER 50S AND AFTERNOON HUMIDITIES AROUND 15
PERCENT LIKELY. WILL HAVE NEAR CRITICAL FIRE WX CONDITIONS IN THIS
AREA...BUT NOT A LOT OF SUPPORT FOR STRONG WINDS EVEN WITH
DEVELOPING LEE TROUGH. CANNOT RULE OUT RED FLAG CONDITIONS
DEVELOPING...BUT CONFIDENCE TOO LOW IN WINDS MATERIALIZING TO ISSUE
WATCH ATTM.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 216 AM MST TUE DEC 11 2012
WED NIGHT-THUR NIGHT...SHORT WAVE RIDGE WILL BE PRIMARY INFLUENCE OF
WEATHER ACROSS THE CWA AS FLOW ALOFT BECOMES MORE AMPLIFIED IN
RESPONSE TO WEST COAST TROUGH. GIVEN THE PATTERN AND VERTICAL
MOISTURE/STABILITY PROFILES...SEE NO REASON WHY DRY CONDITIONS WILL
NOT CONTINUE THROUGH THE PERIOD. SHOULD SEE WARMING TREND THROUGH
THE PERIOD...ESPECIALLY IN OVERNIGHT LOWS. GENERALLY KEPT WELL ABOVE
NORMAL MAX T FORECAST GOING...ALTHOUGH AM A LITTLE CONCERNED THAT
LATEST GUIDANCE INDICATING WEAK FRONTAL ZONE MOVING THROUGH AREA
RESULTING IN LIGHT...BACKED WINDS THURSDAY.
FRIDAY-MONDAY...
MAIN FOCUS CONTINUES TO BE ON UPPER LOW WHICH IS EXPECTED TO DEVELOP
OVER THE SW US AND POSSIBLY IMPACT OUR CWA FRIDAY AFTERNOON THROUGH
EARLY SATURDAY MORNING. AS HAS BEEN THE CASE THE LAST FEW DAYS THE
GEFS AND ECMWF CONTINUE TO SHOW LARGE SPREAD IN SOLUTIONS RUN TO RUN
FOR THIS SYSTEM...WITH THE OPERATIONAL GFS SLIGHTLY MORE CONSISTENT.
THIS TROUGH IS STILL SOUTH OF THE ALEUTIAN ISLANDS OVER THE NORTHERN
PACIFIC....AND UNTIL IT IS BETTER SAMPLED IT IS HARD FOR ME TO MAKE
LARGE CHANGES TO THIS FORECAST PERIOD. CONFIDENCE IS STILL HIGHEST
ACROSS OUR EASTERN CWA...THOUGH I HAVE EXPANDED CHANCE POPS FURTHER
WEST TO ACCOUNT FOR LATEST ECMWF TRENDS. OTHER COMPLICATING FACTOR
IS WAA ADVERTISED BY ECMWF AND GFS WHICH COULD DELAY SNOW CHANGE
OVER. CONSIDERING THE ABSENCE OF STRONG CAA BEHIND THIS SYSTEM...AND
RELIANCE ON EVAPORATIVE PROCESSES FOR CHANGE OVER I AM NOT CONFIDENT
THAT WE WOULD SEE LARGE SNOW ACCUMULATIONS EVEN WITH THE MOST
FAVORABLE TRACKS. I BUMPED UP THE LOW TEMP FORECAST TO LOW 30S
FRIDAY NIGHT AND THIS STILL MIGHT BE TOO COOL IF WE SEE THICK CLOUD
COVER.
SHORTWAVE RIDGING SHOULD KEEP CONDITIONS DRY SATURDAY AND SUNDAY. BY
MONDAY GFS/ECMWF ARE BOTH INDICATING ANOTHER TROUGH IMPACTING THE
HIGH/CENTRAL PLAINS...THOUGH THERE ARE SIGNIFICANT DIFFERENCES IN
EVOLUTION. I DECIDED TO KEEP SLIGHT CHANCE POPS IN PLACE MONDAY AS A
STARTING POINT...SINCE RAIN OR SNOW CANT BE RULED OUT WITH
ADVERTISED PATTERN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1000 PM MST MON DEC 10 2012
VFR THROUGH THE PERIOD AT KGLD AND KMCK. WINDS WILL BACK TO THE
WEST THEN SOUTHWEST WITH SPEEDS AROUND 10KTS OR SO THROUGH THE
DAY TUESDAY AS A LEE TROUGH DEVELOPS TO THE WEST OF THE AREA.
DURING THE EVENING HOURS SOUTH-SOUTHWEST WINDS WILL INCREASE
SLIGHTLY AT KGLD WITH SPEEDS OF 12-15KTS. CLOUDINESS WILL BE
LIMITED TO MID AND UPPER LEVELS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JRM
LONG TERM...JRM/DR
AVIATION...99
AREA FORECAST DISCUSSION
NWS JACKSON KY
307 PM EST TUE DEC 11 2012
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 307 PM EST TUE DEC 11 2012
QUIET WEATHER IS ON TAP FOR THE NEXT SEVERAL DAYS AS HIGH PRESSURE
BUILDS INTO THE REGION TONIGHT AND TOMORROW. HOWEVER...THE MID LEVEL
TROUGH AXIS IS EXPECTED TO STALL JUST TO OUR NORTHWEST TONIGHT.
ONGOING CLOUD COVER WILL LIKELY PERSIST THROUGH TONIGHT AND PERHAPS
EVEN EXPAND BACK INTO AREAS IN THE SOUTHWEST THAT HAVE TEMPORARILY
CLEARED OUT THIS AFTERNOON. THIS MAY HAPPEN DUE TO LIGHT NORTHEAST
LOW LEVEL WINDS. AS MENTIONED EARLIER TODAY...THE CLEARING IN THE
SOUTHWEST WILL ALLOW THOSE AREAS TO BE THE COLDEST TONIGHT WITH LOW
BOTTOMING OUT AROUND 20 OR PERHAPS EVEN A FEW TEENS.
MEANWHILE...FURTHER NORTHEAST...THE CLOUDS WILL KEEP TEMPERATURES IN
THE MIDDLE TO UPPER 20S.
THE MID LEVEL RIDGE AXIS WILL FINALLY PUSH THROUGH EASTERN KENTUCKY
TOMORROW...WITH CLOUDS FINALLY GIVING WAY TO SUNSHINE. THIS WILL HELP
BOOST THE COOL EARLY MORNING READINGS INTO THE 40S BY THE AFTERNOON.
CLEAR SKIES WILL PERSIST INTO WEDNESDAY NIGHT SETTING UP A COLD NIGHT
FOR ALL OF EASTERN KENTUCKY. SEVERAL VALLEY LOCATIONS MAY SEE
TEMPERATURES IN THE TEENS WITH 20S ON THE RIDGES.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 307 PM EST TUE DEC 11 2012
THE EXTENDED PERIOD BEGINS ON THURSDAY MORNING...WITH A LARGE AREA
OF HIGH PRESSURE DOMINATING THE WEATHER ACROSS EASTERN KENTUCKY
THROUGH FRIDAY NIGHT INTO EARLY SATURDAY MORNING. BOTH THE GFS AND
ECMWF MODELS ARE IN VERY GOOD AGREEMENT TO BEGIN THE PERIOD. THE
MODELS HAVE SUBTLE DIFFERENCES IN TIMING OF THE PASSAGE OF ANOTHER
WEATHER SYSTEM OVER THE WEEKEND...SO EITHER MODEL REALLY WOULD HAVE
BEEN A SUITABLE CHOICE FOR THE WEEKENDS WEATHER. HOWEVER...SINCE THE
ECMWF IS USUALLY THE MORE RELIABLE OF THE TWO MODELS...ITS SOLUTION
WAS PREFERRED. THE CONSENSUS IS FOR A WEAKENING COLD FRONT TO MOVE
ACROSS THE OHIO AND TENNESSEE VALLEYS SATURDAY AND SATURDAY NIGHT.
IT APPEARS THAT THE FRONT BEGINS TO SHEAR OUT AS IT MOVES ACROSS THE
AREA THIS WEEKEND...WITH SOME RETURN UPSLOPE FLOW BEHIND IT
PROMOTING LINGERING LIGHT RAIN SHOWERS INTO EARLY SUNDAY NIGHT.
GENERALLY LIGHT RAIN SHOWERS WILL ACCOMPANY THE FRONT AS IT MOVES
PAST.
ANOTHER AREA OF HIGH PRESSURE WILL SETTLE OVER THE REGION MONDAY AND
MONDAY NIGHT...BEFORE ANOTHER AREA OF LOW PRESSURE TAKES SHAPE OVER
THE MIDDLE MISSISSIPPI VALLEY. HOWEVER...IT IS DURING THIS TIME
FRAME THAT THE GFS AND ECMWF MODELS DIVERGE QUITE A BIT...WITH THE
GFS MOVING A LARGE SHIELD OF PRECIPITATION INTO THE AREA BY LATE
TUESDAY MORNING...AND THE ECMWF KEEPING THE AREA DRY FROM MONDAY
NIGHT THROUGH THE END OF THE DAY ON TUESDAY. THE ECWMF COULD BE
UNDERDONE THINGS A LITTLE WITH THE AFOREMENTIONED WEATHER
SYSTEM...SO ADJUSTED THE GRIDS MORE TOWARD THE 12Z RUN OF THE GFS
FOR NOW TO ACCOUNT FOR THIS. THE LATEST VERSION OF THE LONG TERM
ECMWF MOS IS ALSO SHOWING AT LEAST A CHANCE OF RAIN FOR TUESDAY...SO
IT MADE SENSE TO HAVE AT LEAST A CHANCE IN THE FORECAST.
TEMPERATURES WILL CONTINUE TO RUN ABOVE NORMAL THROUGH SUNDAY IN A
SOUTHERLY FLOW REGIME. TEMPERATURES WILL COOL TO NEAR SEASONABLE
LEVELS ON MONDAY AND TUESDAY...AS COOLER AIR SPILLS INTO THE AREA
BEHIND A DEPARTING AREA OF LOW PRESSURE. IN SUMMARY...HIGHS WILL RUN
IN THE LOWER TO MIDDLE 50S FROM THURSDAY THROUGH SUNDAY...BEFORE
COOLING INTO THE MID TO UPPER 40S FROM MONDAY ONWARD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1228 PM EST TUE DEC 11 2012
PESKY MVFR CLOUDS CONTINUE TO HANG AROUND EASTERN KENTUCKY THIS
AFTERNOON. THE 16Z RUC SHOWS THESE CLOUDS HANGING IN THROUGH THE
EVENING AND PERHAPS THROUGH TONIGHT. THUS...HAVE EXTENDED THE CLOUD
COVER IN THE TAFS TO HAVE IT BURN OFF AFTER 13 OR 14Z TOMORROW
MORNING. SOME LOWERING OF THE CIGS CAN BE ANTICIPATED AS THE STRATUS
TRIED TO BUILD DOWNWARDS TONIGHT. CIGS SHOULD BOTTOM OUT AROUND 1500
FEET...BUT COULD GO LOWER IN A FEW AREAS. AFTER TOMORROW
MORNING...VFR CONDITIONS SHOULD BE IN PLACE FOR QUITE SOME TIME TO COME.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...KAS
LONG TERM....AR
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS JACKSON KY
1228 PM EST TUE DEC 11 2012
.UPDATE...
ISSUED AT 1228 PM EST TUE DEC 11 2012
A FEW BREAKS IN THE CLOUDS HAVE FINALLY DEVELOPED ACROSS THE FAR
SOUTHWEST AROUND SOMERSET AND MONTICELLO. THIS MAY BE EVIDENCE THAT
THE WEAK UPSLOPE FLOW MAY HAVE A TOUGH TIME HOLDING CLOUDS ACROSS
THIS AREA. MEANWHILE...CLOUDS STILL LOCKED IN PRETTY GOOD ACROSS THE
REMAINDER OF THE AREA. WILL MAKE NECESSARY TWEAKS TO THE SKY COVER.
IF THE SOUTHWEST CLEARS OUT TONIGHT...WE MAY SEE OUR COOLEST READINGS
DOWN THAT WAY TONIGHT...WHILE SLIGHTLY HIGHER LOWS CAN BE EXPECTED
UNDER THE CLOUD COVER. MAY NEED TO TWEAK THE TEMPERATURE GRIDS TO GET
THIS GRADIENT THIS AFTERNOON. NO PLAN TO ISSUE AN UPDATE AT THIS
TIME...BUT WILL RESEND TO THE NDFD.
UPDATE ISSUED AT 905 AM EST TUE DEC 11 2012
NO EVIDENCE THE CLOUDS ARE GOING TO CLEAR OUT ANYTIME IN THE NEXT 6
TO 12 HOURS AS THE LOW CLOUDS EXTEND WELL BACK TO OUR NORTHWEST. THE
DRIZZLE HAS DIMINISHED WITH THE LACK OF RETURNS ON LOCAL RADAR. THE
12Z RUC HAS A GOOD DEAL OF LOW LEVEL MOISTURE IN PLACE THROUGH 00Z
THIS EVENING. WHILE OTHER OPERATIONAL MODELS SHOW NO SUGGESTION OF
THE CLOUDS CONTINUING...OPTING TO KEEP THEM LONGER THAN PREVIOUSLY
ADVERTISED. IN FACT...GOING TO CARRY A GOOD DEAL OF CLOUD COVER
THROUGH TONIGHT. THIS MAY IMPACT LOWS...BUT DECIDED TO FOCUS ON CLOUD
COVER WITH THIS UPDATE. THERE IS STILL SOME UNCERTAINTY IF/WHEN
CLOUDS MAY CLEAR TONIGHT. IF WE CAN CLEAR OUT LATE...LOWS MAY STILL
BE REALIZED. HOWEVER...CLOUDS WOULD OBVIOUSLY KEEP THINGS A BIT
MILDER. FORECAST UPDATE WILL BE OUT SHORTLY.
UPDATE ISSUED AT 650 AM EST TUE DEC 11 2012
CLOUDS ARE HOLDING ON FAR TO THE WEST EARLY THIS MORNING. WITH SUCH
AN EXPANSE UPSTREAM AND WEAK COLD AIR ADVECTION AND UPSLOPE FLOW TO
PERSIST TODAY...HAVE EXTENDED MOSTLY CLOUDY SKIES THROUGH MORE OF THE
DAY TODAY. WEAK RETURNS ON RADAR HAVE BECOME LIGHTER AND SHIFTED
SOUTHEAST...AND PREVIOUS UPDATE FOR TIMING THE END OF
DRIZZLE/FREEZING DRIZZLE THIS MORNING LOOKS ON TRACK.
UPDATE ISSUED AT 501 AM EST TUE DEC 11 2012
DRIZZLE AND FREEZING DRIZZLE WERE OCCURRING OVER PORTIONS OF THE
SOUTHEAST PART OF THE FORECAST AREA EARLY THIS MORNING...AND HAVE
ADDED IT TO THE FORECAST. AS MOISTURE BECOMES MORE SHALLOW...THIS
SHOULD END LATER THIS MORNING.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 222 AM EST TUE DEC 11 2012
AFTER A PROLONGED PERIOD OF PRECIP...LOW LEVEL MOISTURE LINGERS
IN COLD AIR ADVECTION AND UPSLOPE FLOW BEHIND A COLD FRONT. THE NAM
USED TO BE FAIRLY REASONABLE IN HANDLING COLD UPSLOPE FLOW IN COLD
SEASONS IN YEARS PAST. HOWEVER...IT SEEMS TO BE BEHAVING DIFFERENTLY
THIS AUTUMN. IT IS HANDLING THE LOW LEVEL MOISTURE VERY POORLY
EARLY THIS MORNING WHEN COMPARED TO REALITY ON SATELLITE
IMAGERY...SIMILAR TO AN EARLIER MOIST UPSLOPE FLOW EVENT THIS AUTUMN.
THE GFS LOOKS MORE REASONABLE IN ITS FORECAST...BUT STILL MAY BE A
BIT TOO FAST TO DRY THINGS OUT. WILL TENTATIVELY LOOK FOR CLOUDS TO
BREAK UP THIS AFTERNOON AS SURFACE RIDGING BUILDS IN...BUT
CONFIDENCE IN TIMING IS NOT HIGH. WITH THAT IN MIND...PREFER THE
COOLER HIGH TEMPS SHOWN IN THE GFS MOS FOR TODAY.
ONLY HIGH AND MAINLY THIN CLOUDS ARE EXPECTED OVERNIGHT TONIGHT. WITH
LIGHT WINDS AND A DRY SURFACE AIR MASS HAVING ARRIVED...WILL LOOK
FOR A MODEST RIDGE/VALLEY TEMPERATURE DIFFERENCE FOR LOWS. THE CLOUDS
AND WEAK COLD AIR ADVECTION SHOULD PRECLUDE A LARGER DIFFERENCE.
SURFACE RIDGING WILL REMAIN IN PLACE FOR WEDNESDAY...WITH SUNSHINE
AND SLIGHT WARMER TEMPERATURES.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 222 AM EST TUE DEC 11 2012
THE EXTENDED FORECAST PERIOD BEGINS ON WEDNESDAY NIGHT WITH AN
EXITING TROUGH OFF THE EAST COAST. AFTERWORDS...THE UPPER LEVEL
PATTERN BECOMES ZONAL THROUGH THE REST OF THE WORK WEEK. AT THE
SURFACE...STRONG HIGH PRESSURE WILL STAY POSITIONED OVER APPALACHIA
THROUGH THE WEEK AND INTO SATURDAY. BY FRIDAY...AN TROUGH MOVES
ASHORE THE SOUTHWEST COAST AND INTO THE FOUR CORNERS REGION. MODELS
AGREE ON THE WAVE EJECTING INTO THE CENTRAL PLAINS AND EVENTUALLY
INTO THE MS VALLEY BY 12Z TO 18Z SATURDAY. THE TIMING OF THE GFS AND
EURO ON THE ARRIVAL DO DIVERGE A BIT. ONSET OF PRECIP LOOKS TO BE
LATE SATURDAY. AS WELL...THE 00Z SOLUTION OF THE EURO WOULD SUPPORT
THIS MINDSET AS WELL. WILL ADJUST FOR A SLIGHTLY LATER ARRIVAL FROM
THE SOLUTION PROVIDED FROM THE ALL BLEND MODEL. MODEL SOUNDINGS
WOULD SUGGEST THE POSSIBILITY OF THUNDER WITH THE FRONT INTO SUNDAY.
WILL GO WITH SHOWERS FOR NOW AND WAIT TO SEE IF MODELS HAVE A BETTER
HANDLE ON STABILITY.
CONCERNING TEMPERATURES...A ZONAL PATTERN AND LACK OF ANY
SIGNIFICANT CHANGE IN AIR MASS WILL DURING MUCH OF THE EXTENDED WILL
KEEP TEMPS NEAR IF NOT SLIGHTLY ABOVE NORMAL FOR THE FORECAST AREA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1228 PM EST TUE DEC 11 2012
PESKY MVFR CLOUDS CONTINUE TO HANG AROUND EASTERN KENTUCKY THIS
AFTERNOON. THE 16Z RUC SHOWS THESE CLOUDS HANGING IN THROUGH THE
EVENING AND PERHAPS THROUGH TONIGHT. THUS...HAVE EXTENDED THE CLOUD
COVER IN THE TAFS TO HAVE IT BURN OFF AFTER 13 OR 14Z TOMORROW
MORNING. SOME LOWERING OF THE CIGS CAN BE ANTICIPATED AS THE STRATUS
TRIED TO BUILD DOWNWARDS TONIGHT. CIGS SHOULD BOTTOM OUT AROUND 1500
FEET...BUT COULD GO LOWER IN A FEW AREAS. AFTER TOMORROW
MORNING...VFR CONDITIONS SHOULD BE IN PLACE FOR QUITE SOME TIME TO COME.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...HAL
LONG TERM....SHALLENBERGER
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1221 PM EST TUE DEC 11 2012
...Updated Aviation Discussion...
.Short Term (Today through Wednesday)...
Issued at 300 AM EST Tue Dec 11 2012
In the wake of rapidly exiting low pressure over New England, dry
air has returned to the Lower Ohio Valley. High pressure currently
extends across the southern plains towards the Commonwealth.
Eventually, high pressure will become centered right over Kentucky
by mid-day Wednesday.
Mostly clear, cool, benign weather with light winds will develop
later today and continue through Friday. A stubborn deck of low
clouds will remain in place until after daybreak however. These
strato-cu have not been well forecast by recent mesoscale models,
and persist due to our recent wet weather and quite light winds at
the boundary layer. The RUC is one of the few models that accurately
depict our current strato-cu extending well west across southern
Illinois.
Expect that some clearing will develop across west-central Kentucky
and southwestern Indiana a little bit after dawn. However, the RUC
doesn`t really develop clearing east of Interstate 65 until as late
as noon. To be pessimistic, it is possible that our Bluegrass and
eastern counties may not clear until mid-afternoon or so.
Under light west winds, temperatures will stay cool this afternoon,
with highs ranging from the upper 30s to the lower 40s. For tonight,
expect cold frosty clear conditions with lows falling well down into
the mid 20s. Under clear skies and light winds, Wednesday`s highs
will warm a bit into the mid to upper 40s.
.Long Term (Wednesday Night through Monday)...
Issued at 325 AM EST Tue Dec 11 2012
==============================================
Wednesday Night through Friday Night
Model Preference : Multi-Model Consensus
Forecast Confidence: Medium-High
==============================================
Massive polar vortex looks to stay north of Alaska in the Bering Sea
throughout the upcoming forecast period. This feature combined with
anomalously positive height anomalies across the central Pacific
will lead to a very strong Pacific jet flooding the western US coast
while promoting a deep layer trough to develop. This is not
surprising as the PNA has generally been negative of late and looks
to stay that way through the forecast period according to the
multi-model consensus for which this forecast will lean towards.
With developing trough in the west, downstream ridging is expected
from the Plains and into the eastern US through the period. Small
mid-level wave embedded within the mean flow should be south and
east of our area by Wednesday night. Mid-level heights will rise as
the west coast trough develops, and that combined with surface high
pressure will lead to a dry and quiet weather period through Friday
night. With the upper level ridging building in, we should see a
fairly good moderation in temperatures as the work week ends.
Lows Thursday morning will likely drop into the lower-middle 20s
with possibly some upper teens in the typical colder spots.
However, high temperatures should rebound nicely during the day with
highs reaching the upper 40s across southern Indiana and the
northern half of KY with lower 50s across southern KY. Lows
Thursday night probably will not cool off all that much due to the
increased southerly flow expected. Nonetheless, temperatures should
be near seasonal norms with lows in the upper 20s to around 30.
High temperatures on Friday should be a bit warmer with readings
generally in the 50-55 degree range across southern Indiana and
northern Kentucky. Highs in the mid-upper 50s are likely across
southern Kentucky. Lows Friday night should not be as cold as
clouds will be on the increase ahead of the next weather system.
Probably will see some sort of NE to SW gradient across the area by
late Friday and early Saturday with lows in the lower-mid 30s in the
northeast with upper 30s to around 40 in the central and southwest
sections.
==============================================
Saturday through Tuesday
Model Preference : Euro/Euro Ensembles
Forecast Confidence: Low-Medium
==============================================
Forecast through this period looks rather stormy as a pair of
weather systems will likely affect the region through the period.
The first system is likely to affect the region on Saturday as a
mid-level wave ejects out of the southwestern US and heads northeast
across the Plains and into the Great Lakes. This system will
probably result in another snow storm across the northern plains and
into the western Great Lakes as the low pressure system head
northwest of us. Surface warm front will surge through the region
on Saturday placing us in the warm sector for this storm. Plenty of
clouds and showers will likely accompany the front as it passes
through. As the low slowly heads into the Great Lakes, a surface
cold front will swing through the region sometime on Sunday.
Additional showers and possibly some thunderstorms will be possible
ahead and along the front depending on the instability with the
system. Precipitation will likely push off to the east late Sunday
with cooler, yet seasonal air, pushing back into the region.
After a brief quiet period on Monday, eyes will turn to the next
weather system that is poised to kick out of the southwest US during
the day on Monday. The eventual track of this system is a bit in
question due to the models handling of the developing blocking
pattern across Canada late in the period. While both the GFS and
Euro show the NAO trending negative, each model is very different in
its block configuration. Given the recent 7-day verification of the
Euro and its ensembles over the GFS, have trended the forecast more
toward the Euro at this juncture. With that said, a very strong
closed upper low should eject out of the southern Plains and head
east-northeastward through the Ohio Valley. At the surface, a
strong low pressure system will develop in the lower-Mississippi
Valley and then head north-northeast. The track of the storm looks
to be west of the Ohio Valley, yielding yet another possible snow
storm for the Midwest and western Great Lakes. With the Ohio Valley
remaining on the east side of the system, we`re likely to be warm
sectored again with several round of showers and possible
thunderstorms from Monday night through Tuesday.
Highs Saturday will be above seasonal averages with readings in the
upper middle-upper 50s in the north and upper 50s to around 60 in
the south. Lows Saturday night will cool back into the lower-middle
40s, but only rise slightly on Sunday into the mid-upper 40s. Main
cold push looks to be Sunday night and early Monday with
temperatures falling into the lower-mid 30s. Highs on Monday should
warm back into the lower-middle 40s with overnight lows cooling back
into the middle 30s. Highs on Tuesday look to be in the
middle-upper 40s.
&&
.Aviation (18Z TAF Issuance)...
Issued at 1220 PM EST Tue Dec 11 2012
Main challenge is when the current high-end MVFR ceilings will lift
and/or dissipate. Expect SDF and BWG to scatter out by 19Z and clear
by 20Z, but will take a few hrs longer at LEX. The other fly in the
ointment at LEX is that the ceiling could briefly go VFR before it
scatters out, but either way we are above the fuel-alternate
threshold. The bulk of the clearing in LEX should take place between
20-23Z.
Elongated high pressure will remain parked over the Ohio Valley, so
light west winds this afternoon will go light and variable within
the next few hours, and remain so for the rest of the TAF period.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......JSD
Long Term........MJ
Aviation.........RAS
AREA FORECAST DISCUSSION
NWS JACKSON KY
906 AM EST TUE DEC 11 2012
.UPDATE...
ISSUED AT 905 AM EST TUE DEC 11 2012
NO EVIDENCE THE CLOUDS ARE GOING TO CLEAR OUT ANYTIME IN THE NEXT 6
TO 12 HOURS AS THE LOW CLOUDS EXTEND WELL BACK TO OUR NORTHWEST. THE
DRIZZLE HAS DIMINISHED WITH THE LACK OF RETURNS ON LOCAL RADAR. THE
12Z RUC HAS A GOOD DEAL OF LOW LEVEL MOISTURE IN PLACE THROUGH 00Z
THIS EVENING. WHILE OTHER OPERATIONAL MODELS SHOW NO SUGGESTION OF
THE CLOUDS CONTINUING...OPTING TO KEEP THEM LONGER THAN PREVIOUSLY
ADVERTISED. IN FACT...GOING TO CARRY A GOOD DEAL OF CLOUD COVER
THROUGH TONIGHT. THIS MAY IMPACT LOWS...BUT DECIDED TO FOCUS ON CLOUD
COVER WITH THIS UPDATE. THERE IS STILL SOME UNCERTAINTY IF/WHEN
CLOUDS MAY CLEAR TONIGHT. IF WE CAN CLEAR OUT LATE...LOWS MAY STILL
BE REALIZED. HOWEVER...CLOUDS WOULD OBVIOUSLY KEEP THINGS A BIT
MILDER. FORECAST UPDATE WILL BE OUT SHORTLY.
UPDATE ISSUED AT 650 AM EST TUE DEC 11 2012
CLOUDS ARE HOLDING ON FAR TO THE WEST EARLY THIS MORNING. WITH SUCH
AN EXPANSE UPSTREAM AND WEAK COLD AIR ADVECTION AND UPSLOPE FLOW TO
PERSIST TODAY...HAVE EXTENDED MOSTLY CLOUDY SKIES THROUGH MORE OF THE
DAY TODAY. WEAK RETURNS ON RADAR HAVE BECOME LIGHTER AND SHIFTED
SOUTHEAST...AND PREVIOUS UPDATE FOR TIMING THE END OF
DRIZZLE/FREEZING DRIZZLE THIS MORNING LOOKS ON TRACK.
UPDATE ISSUED AT 501 AM EST TUE DEC 11 2012
DRIZZLE AND FREEZING DRIZZLE WERE OCCURRING OVER PORTIONS OF THE
SOUTHEAST PART OF THE FORECAST AREA EARLY THIS MORNING...AND HAVE
ADDED IT TO THE FORECAST. AS MOISTURE BECOMES MORE SHALLOW...THIS
SHOULD END LATER THIS MORNING.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 222 AM EST TUE DEC 11 2012
AFTER A PROLONGED PERIOD OF PRECIP...LOW LEVEL MOISTURE LINGERS
IN COLD AIR ADVECTION AND UPSLOPE FLOW BEHIND A COLD FRONT. THE NAM
USED TO BE FAIRLY REASONABLE IN HANDLING COLD UPSLOPE FLOW IN COLD
SEASONS IN YEARS PAST. HOWEVER...IT SEEMS TO BE BEHAVING DIFFERENTLY
THIS AUTUMN. IT IS HANDLING THE LOW LEVEL MOISTURE VERY POORLY
EARLY THIS MORNING WHEN COMPARED TO REALITY ON SATELLITE
IMAGERY...SIMILAR TO AN EARLIER MOIST UPSLOPE FLOW EVENT THIS AUTUMN.
THE GFS LOOKS MORE REASONABLE IN ITS FORECAST...BUT STILL MAY BE A
BIT TOO FAST TO DRY THINGS OUT. WILL TENTATIVELY LOOK FOR CLOUDS TO
BREAK UP THIS AFTERNOON AS SURFACE RIDGING BUILDS IN...BUT
CONFIDENCE IN TIMING IS NOT HIGH. WITH THAT IN MIND...PREFER THE
COOLER HIGH TEMPS SHOWN IN THE GFS MOS FOR TODAY.
ONLY HIGH AND MAINLY THIN CLOUDS ARE EXPECTED OVERNIGHT TONIGHT. WITH
LIGHT WINDS AND A DRY SURFACE AIR MASS HAVING ARRIVED...WILL LOOK
FOR A MODEST RIDGE/VALLEY TEMPERATURE DIFFERENCE FOR LOWS. THE CLOUDS
AND WEAK COLD AIR ADVECTION SHOULD PRECLUDE A LARGER DIFFERENCE.
SURFACE RIDGING WILL REMAIN IN PLACE FOR WEDNESDAY...WITH SUNSHINE
AND SLIGHT WARMER TEMPERATURES.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 222 AM EST TUE DEC 11 2012
THE EXTENDED FORECAST PERIOD BEGINS ON WEDNESDAY NIGHT WITH AN
EXITING TROUGH OFF THE EAST COAST. AFTERWORDS...THE UPPER LEVEL
PATTERN BECOMES ZONAL THROUGH THE REST OF THE WORK WEEK. AT THE
SURFACE...STRONG HIGH PRESSURE WILL STAY POSITIONED OVER APPALACHIA
THROUGH THE WEEK AND INTO SATURDAY. BY FRIDAY...AN TROUGH MOVES
ASHORE THE SOUTHWEST COAST AND INTO THE FOUR CORNERS REGION. MODELS
AGREE ON THE WAVE EJECTING INTO THE CENTRAL PLAINS AND EVENTUALLY
INTO THE MS VALLEY BY 12Z TO 18Z SATURDAY. THE TIMING OF THE GFS AND
EURO ON THE ARRIVAL DO DIVERGE A BIT. ONSET OF PRECIP LOOKS TO BE
LATE SATURDAY. AS WELL...THE 00Z SOLUTION OF THE EURO WOULD SUPPORT
THIS MINDSET AS WELL. WILL ADJUST FOR A SLIGHTLY LATER ARRIVAL FROM
THE SOLUTION PROVIDED FROM THE ALL BLEND MODEL. MODEL SOUNDINGS
WOULD SUGGEST THE POSSIBILITY OF THUNDER WITH THE FRONT INTO SUNDAY.
WILL GO WITH SHOWERS FOR NOW AND WAIT TO SEE IF MODELS HAVE A BETTER
HANDLE ON STABILITY.
CONCERNING TEMPERATURES...A ZONAL PATTERN AND LACK OF ANY
SIGNIFICANT CHANGE IN AIR MASS WILL DURING MUCH OF THE EXTENDED WILL
KEEP TEMPS NEAR IF NOT SLIGHTLY ABOVE NORMAL FOR THE FORECAST AREA.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 650 AM EST TUE DEC 11 2012
MVFR CEILINGS PREVAILED AT THE START OF THE PERIOD...WITH LOCALIZED
IFR. THIS SHOULD PERSIST INTO THIS AFTERNOON...WITH CEILINGS THEN
BREAKING UP. VFR IS FORECAST TO RETURN FROM NORTHWEST TO SOUTHEAST
BETWEEN ABOUT 19Z AND 00Z...BUT CONFIDENCE IN THIS TIMING IS
TENTATIVE/LOW CONFIDENCE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...HAL
LONG TERM....SHALLENBERGER
AVIATION...HAL
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
626 AM EST TUE DEC 11 2012
...Updated Aviation Discussion...
.Short Term (Today through Wednesday)...
Issued at 300 AM EST Tue Dec 11 2012
In the wake of rapidly exiting low pressure over New England, dry
air has returned to the Lower Ohio Valley. High pressure currently
extends across the southern plains towards the Commonwealth.
Eventually, high pressure will become centered right over Kentucky
by mid-day Wednesday.
Mostly clear, cool, benign weather with light winds will develop
later today and continue through Friday. A stubborn deck of low
clouds will remain in place until after daybreak however. These
strato-cu have not been well forecast by recent mesoscale models,
and persist due to our recent wet weather and quite light winds at
the boundary layer. The RUC is one of the few models that accurately
depict our current strato-cu extending well west across southern
Illinois.
Expect that some clearing will develop across west-central Kentucky
and southwestern Indiana a little bit after dawn. However, the RUC
doesn`t really develop clearing east of Interstate 65 until as late
as noon. To be pessimistic, it is possible that our Bluegrass and
eastern counties may not clear until mid-afternoon or so.
Under light west winds, temperatures will stay cool this afternoon,
with highs ranging from the upper 30s to the lower 40s. For tonight,
expect cold frosty clear conditions with lows falling well down into
the mid 20s. Under clear skies and light winds, Wednesday`s highs
will warm a bit into the mid to upper 40s.
.Long Term (Wednesday Night through Monday)...
Issued at 325 AM EST Tue Dec 11 2012
==============================================
Wednesday Night through Friday Night
Model Preference : Multi-Model Consensus
Forecast Confidence: Medium-High
==============================================
Massive polar vortex looks to stay north of Alaska in the Bering Sea
throughout the upcoming forecast period. This feature combined with
anomalously positive height anomalies across the central Pacific
will lead to a very strong Pacific jet flooding the western US coast
while promoting a deep layer trough to develop. This is not
surprising as the PNA has generally been negative of late and looks
to stay that way through the forecast period according to the
multi-model consensus for which this forecast will lean towards.
With developing trough in the west, downstream ridging is expected
from the Plains and into the eastern US through the period. Small
mid-level wave embedded within the mean flow should be south and
east of our area by Wednesday night. Mid-level heights will rise as
the west coast trough develops, and that combined with surface high
pressure will lead to a dry and quiet weather period through Friday
night. With the upper level ridging building in, we should see a
fairly good moderation in temperatures as the work week ends.
Lows Thursday morning will likely drop into the lower-middle 20s
with possibly some upper teens in the typical colder spots.
However, high temperatures should rebound nicely during the day with
highs reaching the upper 40s across southern Indiana and the
northern half of KY with lower 50s across southern KY. Lows
Thursday night probably will not cool off all that much due to the
increased southerly flow expected. Nonetheless, temperatures should
be near seasonal norms with lows in the upper 20s to around 30.
High temperatures on Friday should be a bit warmer with readings
generally in the 50-55 degree range across southern Indiana and
northern Kentucky. Highs in the mid-upper 50s are likely across
southern Kentucky. Lows Friday night should not be as cold as
clouds will be on the increase ahead of the next weather system.
Probably will see some sort of NE to SW gradient across the area by
late Friday and early Saturday with lows in the lower-mid 30s in the
northeast with upper 30s to around 40 in the central and southwest
sections.
==============================================
Saturday through Tuesday
Model Preference : Euro/Euro Ensembles
Forecast Confidence: Low-Medium
==============================================
Forecast through this period looks rather stormy as a pair of
weather systems will likely affect the region through the period.
The first system is likely to affect the region on Saturday as a
mid-level wave ejects out of the southwestern US and heads northeast
across the Plains and into the Great Lakes. This system will
probably result in another snow storm across the northern plains and
into the western Great Lakes as the low pressure system head
northwest of us. Surface warm front will surge through the region
on Saturday placing us in the warm sector for this storm. Plenty of
clouds and showers will likely accompany the front as it passes
through. As the low slowly heads into the Great Lakes, a surface
cold front will swing through the region sometime on Sunday.
Additional showers and possibly some thunderstorms will be possible
ahead and along the front depending on the instability with the
system. Precipitation will likely push off to the east late Sunday
with cooler, yet seasonal air, pushing back into the region.
After a brief quiet period on Monday, eyes will turn to the next
weather system that is poised to kick out of the southwest US during
the day on Monday. The eventual track of this system is a bit in
question due to the models handling of the developing blocking
pattern across Canada late in the period. While both the GFS and
Euro show the NAO trending negative, each model is very different in
its block configuration. Given the recent 7-day verification of the
Euro and its ensembles over the GFS, have trended the forecast more
toward the Euro at this juncture. With that said, a very strong
closed upper low should eject out of the southern Plains and head
east-northeastward through the Ohio Valley. At the surface, a
strong low pressure system will develop in the lower-Mississippi
Valley and then head north-northeast. The track of the storm looks
to be west of the Ohio Valley, yielding yet another possible snow
storm for the Midwest and western Great Lakes. With the Ohio Valley
remaining on the east side of the system, we`re likely to be warm
sectored again with several round of showers and possible
thunderstorms from Monday night through Tuesday.
Highs Saturday will be above seasonal averages with readings in the
upper middle-upper 50s in the north and upper 50s to around 60 in
the south. Lows Saturday night will cool back into the lower-middle
40s, but only rise slightly on Sunday into the mid-upper 40s. Main
cold push looks to be Sunday night and early Monday with
temperatures falling into the lower-mid 30s. Highs on Monday should
warm back into the lower-middle 40s with overnight lows cooling back
into the middle 30s. Highs on Tuesday look to be in the
middle-upper 40s.
&&
.Aviation (06Z TAF Issuance)...
Issued at 0020 AM EST Tue Dec 11 2012
Ceilings will be slow to rise and dissipate over the next 6 to 12
hours due to low level moisture and very light winds at the boundary
models. The NAM guidance is too fast in clearing out this moisture
and feel that the RUC is more accurate. Ceilings will slowly lift
before clearing, but MVFR/VFR borderline ceilings will probably
persist through around 12 to 14z at BWG and SDF, after which skies
should clear pretty readily.
Initially lower ceilings at LEX will slowly rise above 2k feet after
10z, before clearing out as late as 15 to 16z. Once skies clear,
expect clear skies through the rest of today and overnight into
Wednesday.
Winds will stay light through the TAF period, starting from the
northwest around 5kt this morning, then slowly backing to the
southwest at less than 5kt by this evening.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......JSD
Long Term........MJ
Aviation.........JSD
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
329 AM EST TUE DEC 11 2012
.Short Term (Today through Wednesday)...
Issued at 300 AM EST Tue Dec 11 2012
In the wake of rapidly exiting low pressure over New England, dry
air has returned to the Lower Ohio Valley. High pressure currently
extends across the southern plains towards the Commonwealth.
Eventually, high pressure will become centered right over Kentucky
by mid-day Wednesday.
Mostly clear, cool, benign weather with light winds will develop
later today and continue through Friday. A stubborn deck of low
clouds will remain in place until after daybreak however. These
strato-cu have not been well forecast by recent mesoscale models,
and persist due to our recent wet weather and quite light winds at
the boundary layer. The RUC is one of the few models that accurately
depict our current strato-cu extending well west across southern
Illinois.
Expect that some clearing will develop across west-central Kentucky
and southwestern Indiana a little bit after dawn. However, the RUC
doesn`t really develop clearing east of Interstate 65 until as late
as noon. To be pessimistic, it is possible that our Bluegrass and
eastern counties may not clear until mid-afternoon or so.
Under light west winds, temperatures will stay cool this afternoon,
with highs ranging from the upper 30s to the lower 40s. For tonight,
expect cold frosty clear conditions with lows falling well down into
the mid 20s. Under clear skies and light winds, Wednesday`s highs
will warm a bit into the mid to upper 40s.
.Long Term (Wednesday Night through Monday)...
Issued at 325 AM EST Tue Dec 11 2012
==============================================
Wednesday Night through Friday Night
Model Preference : Multi-Model Consensus
Forecast Confidence: Medium-High
==============================================
Massive polar vortex looks to stay north of Alaska in the Bering Sea
throughout the upcoming forecast period. This feature combined with
anomalously positive height anomalies across the central Pacific
will lead to a very strong Pacific jet flooding the western US coast
while promoting a deep layer trough to develop. This is not
surprising as the PNA has generally been negative of late and looks
to stay that way through the forecast period according to the
multi-model consensus for which this forecast will lean towards.
With developing trough in the west, downstream ridging is expected
from the Plains and into the eastern US through the period. Small
mid-level wave embedded within the mean flow should be south and
east of our area by Wednesday night. Mid-level heights will rise as
the west coast trough develops, and that combined with surface high
pressure will lead to a dry and quiet weather period through Friday
night. With the upper level ridging building in, we should see a
fairly good moderation in temperatures as the work week ends.
Lows Thursday morning will likely drop into the lower-middle 20s
with possibly some upper teens in the typical colder spots.
However, high temperatures should rebound nicely during the day with
highs reaching the upper 40s across southern Indiana and the
northern half of KY with lower 50s across southern KY. Lows
Thursday night probably will not cool off all that much due to the
increased southerly flow expected. Nonetheless, temperatures should
be near seasonal norms with lows in the upper 20s to around 30.
High temperatures on Friday should be a bit warmer with readings
generally in the 50-55 degree range across southern Indiana and
northern Kentucky. Highs in the mid-upper 50s are likely across
southern Kentucky. Lows Friday night should not be as cold as
clouds will be on the increase ahead of the next weather system.
Probably will see some sort of NE to SW gradient across the area by
late Friday and early Saturday with lows in the lower-mid 30s in the
northeast with upper 30s to around 40 in the central and southwest
sections.
==============================================
Saturday through Tuesday
Model Preference : Euro/Euro Ensembles
Forecast Confidence: Low-Medium
==============================================
Forecast through this period looks rather stormy as a pair of
weather systems will likely affect the region through the period.
The first system is likely to affect the region on Saturday as a
mid-level wave ejects out of the southwestern US and heads northeast
across the Plains and into the Great Lakes. This system will
probably result in another snow storm across the northern plains and
into the western Great Lakes as the low pressure system head
northwest of us. Surface warm front will surge through the region
on Saturday placing us in the warm sector for this storm. Plenty of
clouds and showers will likely accompany the front as it passes
through. As the low slowly heads into the Great Lakes, a surface
cold front will swing through the region sometime on Sunday.
Additional showers and possibly some thunderstorms will be possible
ahead and along the front depending on the instability with the
system. Precipitation will likely push off to the east late Sunday
with cooler, yet seasonal air, pushing back into the region.
After a brief quiet period on Monday, eyes will turn to the next
weather system that is poised to kick out of the southwest US during
the day on Monday. The eventual track of this system is a bit in
question due to the models handling of the developing blocking
pattern across Canada late in the period. While both the GFS and
Euro show the NAO trending negative, each model is very different in
its block configuration. Given the recent 7-day verification of the
Euro and its ensembles over the GFS, have trended the forecast more
toward the Euro at this juncture. With that said, a very strong
closed upper low should eject out of the southern Plains and head
east-northeastward through the Ohio Valley. At the surface, a
strong low pressure system will develop in the lower-Mississippi
Valley and then head north-northeast. The track of the storm looks
to be west of the Ohio Valley, yielding yet another possible snow
storm for the Midwest and western Great Lakes. With the Ohio Valley
remaining on the east side of the system, we`re likely to be warm
sectored again with several round of showers and possible
thunderstorms from Monday night through Tuesday.
Highs Saturday will be above seasonal averages with readings in the
upper middle-upper 50s in the north and upper 50s to around 60 in
the south. Lows Saturday night will cool back into the lower-middle
40s, but only rise slightly on Sunday into the mid-upper 40s. Main
cold push looks to be Sunday night and early Monday with
temperatures falling into the lower-mid 30s. Highs on Monday should
warm back into the lower-middle 40s with overnight lows cooling back
into the middle 30s. Highs on Tuesday look to be in the
middle-upper 40s.
&&
.Aviation (06Z TAF Issuance)...
Issued at 0020 AM EST Tue Dec 11 2012
Ceilings will be slow to rise and dissipate over the next 6 to 12
hours due to low level moisture and very light winds at the boundary
models. The NAM guidance is too fast in clearing out this moisture
and feel that the RUC is more accurate. Ceilings will slowly lift
before clearing, but MVFR/VFR borderline ceilings will probably
persist through around 12 to 14z at BWG and SDF, after which skies
should clear pretty readily.
Initially lower ceilings at LEX will slowly rise above 2k feet after
10z, before clearing out as late as 15 to 16z. Once skies clear,
expect clear skies through the rest of today and overnight into
Wednesday.
Winds will stay light through the TAF period, starting from the
northwest around 5kt this morning, then slowly backing to the
southwest at less than 5kt by this evening.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......JSD
Long Term........MJ
Aviation.........JSD
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1223 AM EST TUE DEC 11 2012
...Updated Aviation Discussion...
.Short Term (Tonight through Tuesday night)...
Issued at 300 PM EST Mon Dec 10 2012
Cold front that moved through before daybreak today is exiting to
the south and east, but the upper trough axis is still working its
way across western Kentucky, and should push through our area by
this evening. Until that happens, low clouds and a mix of cold rain,
snow, and even a few sleet pellets will persist. However, air
temperatures remain a few degrees above freezing, and both soil and
pavement temperatures range from mid-40s to mid-50s, so would not
expect any frozen precip to have a real impact. Most likely scenario
is that snow will melt on contact with the ground.
Biggest question in terms of impact is the potential for wet
roadways to freeze late tonight and early Tuesday morning. Min temps
will drop into the upper 20s in most locations, with mid 20s in the
typical cold spots. WNW winds will stay up around 5-8 mph through
the night, which will help to dry a lot of the residual water on
roadways. This potential drying introduces too much uncertainty to
warrant a travelers advisory, but will provide a heads-up to
transportation officials and possibly mention in HWO.
Chilly high pressure will dominate Tuesday and Tuesday night, with
winds becoming light and variable by mid-afternoon. Max temps will
struggle to crack 40 in this air mass, even under full sunshine.
Went on the low end of guidance because the models do tend to
struggle with these shallow cold air masses. Better radiational
cooling conditions on Tuesday night will allow temps to drop into
the 20s again, only with a bigger spread between urban Louisville
and the sheltered valleys. Some of the traditional cold spots could
bottom out around 20.
.Long Term (Wednesday through Monday)...
Issued at 300 PM EST Mon Dec 10 2012
An upper-level trough will swing through the Ohio Valley Wednesday.
While this will be a dry passage, it will act to clear out the
eastern CONUS and allow for ridging to take hold across the
southeast states. This ridging is also in response to a large low
pressure system diving south along the western CONUS through the end
of the work week. This will set the stage for broad southwest flow
aloft and dry conditions through the end of the work week.
Surface high pressure will shift east across the Ohio Valley and
settle in the southeastern CONUS. Surface winds will transition to
southerly and become breezy by perhaps Friday afternoon, but
especially Saturday as a surface low pressure system moves through
Kansas and Missouri. Dry conditions, mostly clear skies, and warming
temperatures are expected through Friday. Temperatures will continue
to warm through Saturday. High temperatures Wednesday will generally
be in the mid 40s, but will warm solidly into the mid and upper 50s
for Saturday.
Clouds will increase late Friday and precip chances will be on the
rise for the weekend as a low pressure system passes by to the
north. Models agree to disagree with this system, but it appears the
low will pass by to the north, just not sure how far to the north.
The GFS keeps the surface low closer to our area, while the ECMWF
takes it across northern Illinois and is now a little slower with
the front. The GFS is slowly trending toward the ECMWF and the NAEFS
mean solution is much closer to the ECMWF. So, will continue to
trend that direction, which falls in line with the previous forecast.
The trailing cold front is projected to sweep through the forecast
area Saturday night into Sunday, with another shot at area-wide rain
showers. As mentioned in the previous forecast, the trailing cold
front is of Pacific origin. This will cool temperatures slightly
Sunday and Monday. Skies should start to clear late Sunday with
temperatures early next week close to mid-December normals.
&&
.Aviation (06Z TAF Issuance)...
Issued at 0020 AM EST Tue Dec 11 2012
Ceilings will be slow to rise and dissipate over the next 6 to 12
hours due to low level moisture and very light winds at the boundary
models. The NAM guidance is too fast in clearing out this moisture
and feel that the RUC is more accurate. Ceilings will slowly lift
before clearing, but MVFR/VFR borderline ceilings will probably
persist through around 12 to 14z at BWG and SDF, after which skies
should clear pretty readily.
Initially lower ceilings at LEX will slowly rise above 2k feet after
10z, before clearing out as late as 15 to 16z. Once skies clear,
expect clear skies through the rest of today and overnight into
Wednesday.
Winds will stay light through the TAF period, starting from the
northwest around 5kt this morning, then slowly backing to the
southwest at less than 5kt by this evening.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......RS
Long Term........MP
Aviation.........JSD
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
936 PM EST WED DEC 12 2012
.UPDATE...
ISSUED AT 934 PM EST WED DEC 12 2012
STRONG S WINDS...WITH GUST AS HI AS 40 MPH AT PARENT BAY ON THE
SHORE OF SCHOOLCRAFT COUNTY UNDER 37KT WIND REPORTED ON THE 00Z GRB
RAOB AT 2K FT AGL...IN ADVANCE OF LO PRES IN MN HAS LIFTED
TEMPERATURES INTO THE 30S AT MOST LOCATIONS. SO TENDED TO BUMP UP
TEMPS A COUPLE OF DEGREES FM PREVIOUS FCST UNDER MID/HI OVC. WINDS WL
DIMINISH LATER...SO TEMPS MIGHT FALL AGAIN A BIT LATER.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 427 PM EST WED DEC 12 2012
WATER VAPOR LOOP AND RUC ANALYSIS SHOWS AN AMPLIFIED TROF OFF THE
WEST COAST WITH BROAD TROUGH CENTERED OVER HUDSON BAY DOMINATING
MUCH OF CANADA. AT THE SFC...A STATIONARY FRONT IS DRAPED OVER NORTH
DAKOTA...NRN MN INTO WRN UPR MI. A SHORTWAVE MOVING ACROSS SOUTHERN
CANADA ALONG WITH ITS ASSOC MID-LVL Q-VECT CONV AND 800 MB FGEN HAS
SUPPORTED AN AREA OF LIGHT SNOW THIS AFTERNOON OVER SRN MANITOBA AND
WRN ONTARIO.
TONIGHT...BEST FGEN FORCING AND Q-VECT CONV WITH SRN CANADA
SHORTWAVE IS FCST BY MODELS TO STAY MAINLY NORTH OF THE CWA TONIGHT.
THUS...IT ALSO MAKES SENSE THAT MODEL QPF ALSO STAYS MAINLY NORTH OF
THE AREA. MAINTAINED SLGT CHC POPS OVER THE TIP OF THE KEWEENAW AND
NRN LAKE SUPERIOR AS WEAK FORCING COULD BRUSH THESE AREAS WITH LIGHT
SNOW AND POSSIBLY DZ/FZDZ AS THERE IS A DRY LAYER ALOFT WHICH COULD
TEMPORARILY DISRUPT ICE CRYSTAL NUCLEATION. TEMPS SHOULDN`T DROP
MUCH TONIGHT UNDER CLOUDS AND INCREASING BLYR WINDS. EXPECT LOWS
FROM THE MID 20S INTERIOR WEST TO THE UPPER 20S/LOWER 30S
ELSEWHERE.
THURSDAY...A 120 KT 3H JET STREAK STREAMING EAST FROM THE CENTRAL
ROCKIES COMBINED WITH INCREASING 850-800 MB FGEN IN LEFT EXIT REGION
OF JET HAVE MOST MODELS SUPPORTING A NARROW BAND OF PCPN OVER THE
KEWEENAW PENINSULA LATE THU MORNING INTO EARLY AFTERNOON. CONTINUED
DRY LAYER AT MID-LVLS MAY DISRUPT ICE CRYSTAL NUCLEATION TO SUPPORT
SOME DZ/FZDZ MIXING IN WITH LIGHT SNOW. EXPECT ONLY A DUSTING OF
SNOW (HALF INCH OF LESS) OVER THE KEWEENAW AND MAINTAINED JUST HIGH
CHC POPS FOR NOW.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 427 PM EST WED DEC 12 2012
A MORE ACTIVE PATTERN LOOKS TO BE DEVELOPING BY THE END OF THE
WEEK...WITH THE MAIN FOCUS ON A POTENTIAL FOR MODERATE SNOWFALL
ACROSS MUCH OF THE AREA ON SATURDAY...AND THEN LIGHTER SNOW LASTING
INTO NEXT WEEK.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...THE LARGE SCALE FLOW WILL BE
GENERALLY ZONAL OVER THE GREAT LAKES REGION SOUTH OF A BROAD
MID-LEVEL LOW ACROSS HUDSON BAY AND NORTHERN QUEBEC. MEANWHILE...A
WEAK SHORTWAVE TROUGH WILL BE MOVING ESE ACROSS SOUTHERN MANITOBA
INTO WESTERN ONTARIO...AND A DEEP TROUGH WILL BE MOVING ONSHORE IN
CENTRAL AND SOUTHERN CA. THE DEEP WESTERN TROUGH WILL BE THE FOCUS
FOR SATURDAY ONWARD. BEFORE THEN...THE SHORTWAVE TROUGH IN SOUTHERN
CANADA WILL TRACK ACROSS WESTERN ONTARIO THURSDAY NIGHT...AND INTO
EASTERN ONTARIO BY FRIDAY AFTERNOON. INFLUENCE OF THIS TROUGH IS A
BIT WEAK ACROSS UPPER MI...AND MID-RANGE MODELS HAVE SOME
DISAGREEMENT ON PRECIP CHANCES. MID/UPPER FORCING IS NOT IMPRESSIVE
BY ANY MEANS UNTIL THE RIGHT ENTRANCE OF A 120KT UPPER JET CROSSES
THE CWA FRIDAY MORNING. BY THIS TIME...THE MID-LEVEL TROUGH WILL
ALMOST BE THROUGH THE AREA...WITH MID-LEVEL SUBSIDENCE/DRYING TAKING
HOLD. HOWEVER...LOW-LEVEL MOISTURE LINGERS...ESPECIALLY ACROSS THE
NORTHERN HALF OF THE CWA. WIND IS RATHER LIGHT AND VARIABLE THURSDAY
NIGHT THROUGH FRIDAY MORNING...BUT FAVORABLE DIRECTION IS BETWEEN N
AND E. WILL KEEP GENERAL SLIGHT CHANCE OF FZDZ NORTH...AND HAVE
EXPANDED IT SLIGHTLY TO ACCOUNT FOR TERRAIN EFFECTS.
OVERALL...EXPECT THE BEST CHANCE OF FZDZ TO BE LATE THURSDAY NIGHT
BEFORE DIMINISHING FRIDAY MORNING AS WINDS VEER TO THE SE.
BY FRIDAY EVENING...LOW LEVEL MOISTURE ADVECTING NORTHWARD AHEAD OF
THE NEXT SYSTEM WILL BRING ANOTHER POTENTIAL FOR FREEZING
DRIZZLE...THIS TIME ACROSS THE SOUTH-CENTRAL. SOUTHEAST WINDS OFF OF
LAKE MICHIGAN WILL ASSIST WITH THE MOISTURE SUPPLY...BUT THE
MOISTURE WILL BE SHALLOW (2KFT) AS A RESULT OF DRYING/SUBSIDENCE
UNDER A DEPARTING RIDGE. HAVE MENTIONED A SLIGHT CHANCE OF FREEZING
DRIZZLE IN THE HIGHER TERRAIN ACROSS THE SOUTH-CENTRAL...MAINLY
FOCUSED IN DICKINSON AND SOUTHERN MARQUETTE COUNTIES. INCREASING
CLOUD COVER COMBINED WITH STRENGTHENING WINDS SHOULD RESULT IN A
STEADY TEMP RISE THROUGHOUT THE NIGHT...WITH LOCATIONS ALONG LAKE
MICHIGAN REACHING ABOVE FREEZING BY DAY BREAK.
SATURDAY...RATHER COMPLICATED FORECAST CONCERNING THE POTENTIAL FOR
A STRONG LOW PRESSURE SYSTEM MOVING INTO THE AREA SATURDAY.
CONFIDENCE IS RUNNING LOW WITH THIS SYSTEM ATTM FOR SEVERAL REASONS.
FIRST...THE MID-LEVEL TROUGH IS STILL BARRELING SOUTHWARD ALONG THE
CA COAST THIS AFTERNOON...SO WHERE IT MAKES AN EASTWARD TURN WILL
HAVE SOME IMPLICATION ON OVERALL PLACEMENT AS IT MOVES OUT OF THE
LEE OF THE ROCKIES. ALL LONG TERM MODELS ARE IN GENERAL AGREEMENT OF
THE INITIAL PROGRESSION TAKING THE TROUGH THROUGH NORTHERN AZ. THIS
IS THE POINT WHERE THE MODELS DIVERGE...WITH THE EMERGENCE OF THE
LEE LOW RANGING FROM NEAR DENVER TO THE OK PANHANDLE. DIFFERENCES
CONTINUE TO GROW FROM THERE ON.
THE SECOND ISSUE COMES FROM THE TIMING OF ANOTHER SHORTWAVE TROUGH
MOVING ACROSS SOUTHERN CANADA AS EACH MODEL IS HANDLING THE STRENGTH
AND TIMING DIFFERENTLY. THE NAM IS THE STRONGEST/QUICKEST WITH THE
NORTHERN TROUGH...RESULTING IN AN INTERACTION WITH THE SOUTHERN
TROUGH MUCH FARTHER WEST ACROSS MN. MEANWHILE...THE ECMWF IS MUCH
MORE OPEN WITH THE TROUGH...AND INTERACTS WITH THE SOUTHERN TROUGH
OVER WI.
FINALLY...THE NAM AND GFS ARE BOTH PRODUCING AROUND 1 INCH OF LIQUID
PRECIP ACROSS IL ON SATURDAY...WHICH COULD RESULT IN A LACK OF
MOISTURE AVAILABILITY THIS FAR NORTH.
OVERALL THINKING IS THAT THE WESTWARD TRENDS OF THE MODELS ARE
BELIEVABLE...ESPECIALLY AS THE GFS COMES INTO LINE WITH THE MORE
CONSISTENT ECMWF. THEREFORE...A BLEND OF THOSE TWO MODELS WAS USED
FOR THIS SYSTEM. THE TWO TRACK THE SFC LOW THROUGH SOUTHERN WI LATE
SATURDAY AFTERNOON...AND INTO NORTHERN LOWER MI BY SUNDAY MORNING.
EVEN THOUGH H8 TEMPS CREEP ABOVE FREEZING AHEAD OF THE SYSTEM ON
SATURDAY...DRY AIR UNDER THE DEPARTING RIDGE WILL KEEP WET BULB
TEMPS BELOW FREEZING THROUGHOUT THE COLUMN. THERMAL PROFILES SUGGEST
A VERY WET SNOWFALL FOR THE CWA...WITH RAIN MIXING IN ACROSS THE
SOUTH CENTRAL AND EAST NEAR LAKE MICHIGAN. THOUGH THERE ARE SO MANY
DISCREPANCIES AMONG THE MODELS...THERE IS FAIRLY GOOD AGREEMENT THAT
A SHIELD OF MODERATE SNOW WILL MOVE NORTHEASTWARD THROUGH THE
CWA...BEGINNING SATURDAY MORNING NEAR THE MI/WI BORDER...AND
SATURDAY AFTERNOON ALONG LAKE SUPERIOR. PINPOINTING ANY AREAS FOR
ENHANCED SNOWFALL ATTM IS QUITE DIFFICULT...BUT THERE IS A STRONG
SIGNAL OF A H8-H7 FRONTOGENESIS BAND JUST NORTH OF THE LEFT EXIT OF
THE UPPER JET...WHEREVER THOSE FEATURES END UP.
NOT LOOKING LIKE WE WILL REACH WARNING CRITERIA (6IN/12HR)
SNOWFALL...BUT SNOW COULD ACCUMULATE QUICKLY AT TIMES ON SATURDAY.
GIVEN THE WATER CONTENT OF THE SNOW...THINGS COULD GET SLOPPY ACROSS
THE CWA.
SUNDAY THROUGH WEDNESDAY...THE FORECAST BECOMES MUDDLED BY THE END
OF THE WEEKEND AS THE MID-LEVEL LOW RESPONSIBLE FOR SATURDAYS SYSTEM
BECOMES WRAPPED UP ACROSS ONTARIO. THIS WILL PUT UPPER MI IN WEAK
NORTH TO NORTHWEST FLOW THROUGH MUCH OF THE REMAINDER OF THE PERIOD.
THE MAIN RESERVOIR OF COLD AIR IS CURRENTLY WELL TO THE NORTH ACROSS
THE ARCTIC AND SIBERIA...AND NOT REALLY A MAJOR FACTOR FOR LAKE
ENHANCEMENT/LAKE EFFECT OVER THE NEXT WEEK. THE COLDEST H8 AIR
BEHIND THE SYSTEM WILL MOVE ACROSS LAKE SUPERIOR SUNDAY NIGHT. EVEN
THEN...TEMPS ARE STILL ONLY AS LOW AS -10C. ALSO...INVERSION LEVELS
ARE ONLY ABOUT 4-5KFT FOR MUCH OF THE PERIOD. THE EXPECTATION IS
THAT THERE WILL BE INTERMITTENT SNOW SHOWERS...MAINLY NEAR LAKE
SUPERIOR...INTO THE MIDDLE OF NEXT WEEK. ACCUMULATIONS WILL BE LIGHT.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 644 PM EST WED DEC 12 2012
WITH SW FLOW OF DRY AIR TO THE S OF WARM FNT OVER NRN LK SUP...
EXPECT VFR CONDITIONS TO PREDOMINATE INTO THU MRNG. THERE WL BE SOME
LLWS AT ALL 3 SITES AS WELL INTO THE EARLY MRNG HRS ON THU WITH LLJ
MOVING OVHD. THE APRCH OF AN UPPER DISTURBANCE FM THE NRN PLAINS AND
A SLOW MOVING COLD FNT COULD RESULT IN SOME LGT PCPN TO MAINLY CMX
ON THU. WITH RELATIVELY SHALLOW INFUSION OF COLDER/MOISTER AIR
BEHIND THE FROPA...CONDITIONS ARE LIKELY TO FALL TO MVFR FIRST AT
CMX BY NOON AND THEN AT IWD LATER IN THE AFTN. IFR CONDITIONS AND
SOME -FZDZ ARE POSSIBLE AT CMX. RIGHT NOW...IT APPEARS THE FROPA WL
OCCUR TOO LATE AT SAW TO IMPACT THAT SITE DURING THIS TAF PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 934 PM EST WED DEC 12 2012
UPDATE FOR 10 PM LAKE ISSUANCE...OPTED TO ISSUE GALE WARNING FOR THE
2 EAST ZONES GIVEN SHIP OB OF GUST UP TO 41 KTS AND 01Z CARIBOU
ISLAND REPORT OF 33 KT GUST. THE 00Z GREEN BAY WI RAOB SHOWED A 37KT
WIND AT 2K FT AGL...AND SUSPECT THIS HIER MOMENTUM WILL IMPACT THE E
PART OF LK SUP TO THE S OF PRES FALL CENTER THAT IS FORECAST TO DRIFT
ACROSS THE N PORTIONS OF THE LK THRU EARLY THU MORNING. RATHER
UNSTABLE TEMP PROFILE ALSO SHOULD SUPPORT MIXING OF THE HIER WINDS.
EXPECT SOUTH WINDS TO INCREASE OVER MOST OF LK SUPERIOR LATE THIS
AFTN AND ESPECIALLY TONIGHT. GUSTS TO GALES POSSIBLE EAST...BUT NOT
FREQUENT/STRONG ENOUGH TO ISSUE GALE WARNING. WINDS DIMINISH
STEADILY BLO 20 KTS LATER THURSDAY INTO THURSDAY NIGHT AS A WEAK
TROUGH CROSSES THE LAKE. WINDS STAY BLO 20 KTS THROUGH FRIDAY NIGHT
AS PRESSURE GRADIENT IS WEAK.
A LOW PRESSURE SYSTEM DEVELOPING IN THE PLAINS STILL ON TRACK TO
PUSH INTO WESTERN GREAT LAKES LATE SATURDAY INTO SUNDAY WHILE HIGH
PRESSURE MOVES ACROSS NEW ENGLAND. WINDS SHOULD INCREASE FROM THE
EAST TO 30 KTS LATE SATURDAY OVER LAKE SUPERIOR. EXACT TRACK AND
DEPTH OF SFC LOW REMAINS UNCERTAIN THOUGH SO KEPT WINDS BELOW GALE
IN THIS FORECAST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING UNTIL 4 AM EST THURSDAY FOR LSZ266-267.
LAKE MICHIGAN...
GALE WARNING UNTIL 7 AM EST THURSDAY FOR LMZ248-250.
&&
$$
UPDATE...KC
SHORT TERM...VOSS
LONG TERM...TK
AVIATION...KC
MARINE...VOSS/KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
644 PM EST WED DEC 12 2012
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 427 PM EST WED DEC 12 2012
WATER VAPOR LOOP AND RUC ANALYSIS SHOWS AN AMPLIFIED TROF OFF THE
WEST COAST WITH BROAD TROUGH CENTERED OVER HUDSON BAY DOMINATING
MUCH OF CANADA. AT THE SFC...A STATIONARY FRONT IS DRAPED OVER NORTH
DAKOTA...NRN MN INTO WRN UPR MI. A SHORTWAVE MOVING ACROSS SOUTHERN
CANADA ALONG WITH ITS ASSOC MID-LVL Q-VECT CONV AND 800 MB FGEN HAS
SUPPORTED AN AREA OF LIGHT SNOW THIS AFTERNOON OVER SRN MANITOBA AND
WRN ONTARIO.
TONIGHT...BEST FGEN FORCING AND Q-VECT CONV WITH SRN CANADA
SHORTWAVE IS FCST BY MODELS TO STAY MAINLY NORTH OF THE CWA TONIGHT.
THUS...IT ALSO MAKES SENSE THAT MODEL QPF ALSO STAYS MAINLY NORTH OF
THE AREA. MAINTAINED SLGT CHC POPS OVER THE TIP OF THE KEWEENAW AND
NRN LAKE SUPERIOR AS WEAK FORCING COULD BRUSH THESE AREAS WITH LIGHT
SNOW AND POSSIBLY DZ/FZDZ AS THERE IS A DRY LAYER ALOFT WHICH COULD
TEMPORARILY DISRUPT ICE CRYSTAL NUCLEATION. TEMPS SHOULDN`T DROP
MUCH TONIGHT UNDER CLOUDS AND INCREASING BLYR WINDS. EXPECT LOWS
FROM THE MID 20S INTERIOR WEST TO THE UPPER 20S/LOWER 30S
ELSEWHERE.
THURSDAY...A 120 KT 3H JET STREAK STREAMING EAST FROM THE CENTRAL
ROCKIES COMBINED WITH INCREASING 850-800 MB FGEN IN LEFT EXIT REGION
OF JET HAVE MOST MODELS SUPPORTING A NARROW BAND OF PCPN OVER THE
KEWEENAW PENINSULA LATE THU MORNING INTO EARLY AFTERNOON. CONTINUED
DRY LAYER AT MID-LVLS MAY DISRUPT ICE CRYSTAL NUCLEATION TO SUPPORT
SOME DZ/FZDZ MIXING IN WITH LIGHT SNOW. EXPECT ONLY A DUSTING OF
SNOW (HALF INCH OF LESS) OVER THE KEWEENAW AND MAINTAINED JUST HIGH
CHC POPS FOR NOW.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 427 PM EST WED DEC 12 2012
A MORE ACTIVE PATTERN LOOKS TO BE DEVELOPING BY THE END OF THE
WEEK...WITH THE MAIN FOCUS ON A POTENTIAL FOR MODERATE SNOWFALL
ACROSS MUCH OF THE AREA ON SATURDAY...AND THEN LIGHTER SNOW LASTING
INTO NEXT WEEK.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...THE LARGE SCALE FLOW WILL BE
GENERALLY ZONAL OVER THE GREAT LAKES REGION SOUTH OF A BROAD
MID-LEVEL LOW ACROSS HUDSON BAY AND NORTHERN QUEBEC. MEANWHILE...A
WEAK SHORTWAVE TROUGH WILL BE MOVING ESE ACROSS SOUTHERN MANITOBA
INTO WESTERN ONTARIO...AND A DEEP TROUGH WILL BE MOVING ONSHORE IN
CENTRAL AND SOUTHERN CA. THE DEEP WESTERN TROUGH WILL BE THE FOCUS
FOR SATURDAY ONWARD. BEFORE THEN...THE SHORTWAVE TROUGH IN SOUTHERN
CANADA WILL TRACK ACROSS WESTERN ONTARIO THURSDAY NIGHT...AND INTO
EASTERN ONTARIO BY FRIDAY AFTERNOON. INFLUENCE OF THIS TROUGH IS A
BIT WEAK ACROSS UPPER MI...AND MID-RANGE MODELS HAVE SOME
DISAGREEMENT ON PRECIP CHANCES. MID/UPPER FORCING IS NOT IMPRESSIVE
BY ANY MEANS UNTIL THE RIGHT ENTRANCE OF A 120KT UPPER JET CROSSES
THE CWA FRIDAY MORNING. BY THIS TIME...THE MID-LEVEL TROUGH WILL
ALMOST BE THROUGH THE AREA...WITH MID-LEVEL SUBSIDENCE/DRYING TAKING
HOLD. HOWEVER...LOW-LEVEL MOISTURE LINGERS...ESPECIALLY ACROSS THE
NORTHERN HALF OF THE CWA. WIND IS RATHER LIGHT AND VARIABLE THURSDAY
NIGHT THROUGH FRIDAY MORNING...BUT FAVORABLE DIRECTION IS BETWEEN N
AND E. WILL KEEP GENERAL SLIGHT CHANCE OF FZDZ NORTH...AND HAVE
EXPANDED IT SLIGHTLY TO ACCOUNT FOR TERRAIN EFFECTS.
OVERALL...EXPECT THE BEST CHANCE OF FZDZ TO BE LATE THURSDAY NIGHT
BEFORE DIMINISHING FRIDAY MORNING AS WINDS VEER TO THE SE.
BY FRIDAY EVENING...LOW LEVEL MOISTURE ADVECTING NORTHWARD AHEAD OF
THE NEXT SYSTEM WILL BRING ANOTHER POTENTIAL FOR FREEZING
DRIZZLE...THIS TIME ACROSS THE SOUTH-CENTRAL. SOUTHEAST WINDS OFF OF
LAKE MICHIGAN WILL ASSIST WITH THE MOISTURE SUPPLY...BUT THE
MOISTURE WILL BE SHALLOW (2KFT) AS A RESULT OF DRYING/SUBSIDENCE
UNDER A DEPARTING RIDGE. HAVE MENTIONED A SLIGHT CHANCE OF FREEZING
DRIZZLE IN THE HIGHER TERRAIN ACROSS THE SOUTH-CENTRAL...MAINLY
FOCUSED IN DICKINSON AND SOUTHERN MARQUETTE COUNTIES. INCREASING
CLOUD COVER COMBINED WITH STRENGTHENING WINDS SHOULD RESULT IN A
STEADY TEMP RISE THROUGHOUT THE NIGHT...WITH LOCATIONS ALONG LAKE
MICHIGAN REACHING ABOVE FREEZING BY DAY BREAK.
SATURDAY...RATHER COMPLICATED FORECAST CONCERNING THE POTENTIAL FOR
A STRONG LOW PRESSURE SYSTEM MOVING INTO THE AREA SATURDAY.
CONFIDENCE IS RUNNING LOW WITH THIS SYSTEM ATTM FOR SEVERAL REASONS.
FIRST...THE MID-LEVEL TROUGH IS STILL BARRELING SOUTHWARD ALONG THE
CA COAST THIS AFTERNOON...SO WHERE IT MAKES AN EASTWARD TURN WILL
HAVE SOME IMPLICATION ON OVERALL PLACEMENT AS IT MOVES OUT OF THE
LEE OF THE ROCKIES. ALL LONG TERM MODELS ARE IN GENERAL AGREEMENT OF
THE INITIAL PROGRESSION TAKING THE TROUGH THROUGH NORTHERN AZ. THIS
IS THE POINT WHERE THE MODELS DIVERGE...WITH THE EMERGENCE OF THE
LEE LOW RANGING FROM NEAR DENVER TO THE OK PANHANDLE. DIFFERENCES
CONTINUE TO GROW FROM THERE ON.
THE SECOND ISSUE COMES FROM THE TIMING OF ANOTHER SHORTWAVE TROUGH
MOVING ACROSS SOUTHERN CANADA AS EACH MODEL IS HANDLING THE STRENGTH
AND TIMING DIFFERENTLY. THE NAM IS THE STRONGEST/QUICKEST WITH THE
NORTHERN TROUGH...RESULTING IN AN INTERACTION WITH THE SOUTHERN
TROUGH MUCH FARTHER WEST ACROSS MN. MEANWHILE...THE ECMWF IS MUCH
MORE OPEN WITH THE TROUGH...AND INTERACTS WITH THE SOUTHERN TROUGH
OVER WI.
FINALLY...THE NAM AND GFS ARE BOTH PRODUCING AROUND 1 INCH OF LIQUID
PRECIP ACROSS IL ON SATURDAY...WHICH COULD RESULT IN A LACK OF
MOISTURE AVAILABILITY THIS FAR NORTH.
OVERALL THINKING IS THAT THE WESTWARD TRENDS OF THE MODELS ARE
BELIEVABLE...ESPECIALLY AS THE GFS COMES INTO LINE WITH THE MORE
CONSISTENT ECMWF. THEREFORE...A BLEND OF THOSE TWO MODELS WAS USED
FOR THIS SYSTEM. THE TWO TRACK THE SFC LOW THROUGH SOUTHERN WI LATE
SATURDAY AFTERNOON...AND INTO NORTHERN LOWER MI BY SUNDAY MORNING.
EVEN THOUGH H8 TEMPS CREEP ABOVE FREEZING AHEAD OF THE SYSTEM ON
SATURDAY...DRY AIR UNDER THE DEPARTING RIDGE WILL KEEP WET BULB
TEMPS BELOW FREEZING THROUGHOUT THE COLUMN. THERMAL PROFILES SUGGEST
A VERY WET SNOWFALL FOR THE CWA...WITH RAIN MIXING IN ACROSS THE
SOUTH CENTRAL AND EAST NEAR LAKE MICHIGAN. THOUGH THERE ARE SO MANY
DISCREPANCIES AMONG THE MODELS...THERE IS FAIRLY GOOD AGREEMENT THAT
A SHIELD OF MODERATE SNOW WILL MOVE NORTHEASTWARD THROUGH THE
CWA...BEGINNING SATURDAY MORNING NEAR THE MI/WI BORDER...AND
SATURDAY AFTERNOON ALONG LAKE SUPERIOR. PINPOINTING ANY AREAS FOR
ENHANCED SNOWFALL ATTM IS QUITE DIFFICULT...BUT THERE IS A STRONG
SIGNAL OF A H8-H7 FRONTOGENESIS BAND JUST NORTH OF THE LEFT EXIT OF
THE UPPER JET...WHEREVER THOSE FEATURES END UP.
NOT LOOKING LIKE WE WILL REACH WARNING CRITERIA (6IN/12HR)
SNOWFALL...BUT SNOW COULD ACCUMULATE QUICKLY AT TIMES ON SATURDAY.
GIVEN THE WATER CONTENT OF THE SNOW...THINGS COULD GET SLOPPY ACROSS
THE CWA.
SUNDAY THROUGH WEDNESDAY...THE FORECAST BECOMES MUDDLED BY THE END
OF THE WEEKEND AS THE MID-LEVEL LOW RESPONSIBLE FOR SATURDAYS SYSTEM
BECOMES WRAPPED UP ACROSS ONTARIO. THIS WILL PUT UPPER MI IN WEAK
NORTH TO NORTHWEST FLOW THROUGH MUCH OF THE REMAINDER OF THE PERIOD.
THE MAIN RESERVOIR OF COLD AIR IS CURRENTLY WELL TO THE NORTH ACROSS
THE ARCTIC AND SIBERIA...AND NOT REALLY A MAJOR FACTOR FOR LAKE
ENHANCEMENT/LAKE EFFECT OVER THE NEXT WEEK. THE COLDEST H8 AIR
BEHIND THE SYSTEM WILL MOVE ACROSS LAKE SUPERIOR SUNDAY NIGHT. EVEN
THEN...TEMPS ARE STILL ONLY AS LOW AS -10C. ALSO...INVERSION LEVELS
ARE ONLY ABOUT 4-5KFT FOR MUCH OF THE PERIOD. THE EXPECTATION IS
THAT THERE WILL BE INTERMITTENT SNOW SHOWERS...MAINLY NEAR LAKE
SUPERIOR...INTO THE MIDDLE OF NEXT WEEK. ACCUMULATIONS WILL BE LIGHT.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 644 PM EST WED DEC 12 2012
WITH SW FLOW OF DRY AIR TO THE S OF WARM FNT OVER NRN LK SUP...
EXPECT VFR CONDITIONS TO PREDOMINATE INTO THU MRNG. THERE WL BE SOME
LLWS AT ALL 3 SITES AS WELL INTO THE EARLY MRNG HRS ON THU WITH LLJ
MOVING OVHD. THE APRCH OF AN UPPER DISTURBANCE FM THE NRN PLAINS AND
A SLOW MOVING COLD FNT COULD RESULT IN SOME LGT PCPN TO MAINLY CMX
ON THU. WITH RELATIVELY SHALLOW INFUSION OF COLDER/MOISTER AIR
BEHIND THE FROPA...CONDITIONS ARE LIKELY TO FALL TO MVFR FIRST AT
CMX BY NOON AND THEN AT IWD LATER IN THE AFTN. IFR CONDITIONS AND
SOME -FZDZ ARE POSSIBLE AT CMX. RIGHT NOW...IT APPEARS THE FROPA WL
OCCUR TOO LATE AT SAW TO IMPACT THAT SITE DURING THIS TAF PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 427 PM EST WED DEC 12 2012
EXPECT SOUTH WINDS TO INCREASE OVER MOST OF LK SUPERIOR LATE THIS
AFTN AND ESPECIALLY TONIGHT. GUSTS TO GALES POSSIBLE EAST...BUT NOT
FREQUENT/STRONG ENOUGH TO ISSUE GALE WARNING. WINDS DIMINISH
STEADILY BLO 20 KTS LATER THURSDAY INTO THURSDAY NIGHT AS A WEAK
TROUGH CROSSES THE LAKE. WINDS STAY BLO 20 KTS THROUGH FRIDAY NIGHT
AS PRESSURE GRADIENT IS WEAK.
A LOW PRESSURE SYSTEM DEVELOPING IN THE PLAINS STILL ON TRACK TO
PUSH INTO WESTERN GREAT LAKES LATE SATURDAY INTO SUNDAY WHILE HIGH
PRESSURE MOVES ACROSS NEW ENGLAND. WINDS SHOULD INCREASE FROM THE
EAST TO 30 KTS LATE SATURDAY OVER LAKE SUPERIOR. EXACT TRACK AND
DEPTH OF SFC LOW REMAINS UNCERTAIN THOUGH SO KEPT WINDS BELOW GALE
IN THIS FORECAST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
GALE WARNING UNTIL 7 AM EST THURSDAY FOR LMZ248-250.
&&
$$
SHORT TERM...VOSS
LONG TERM...TK
AVIATION...KC
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
425 PM EST TUE DEC 11 2012
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 424 PM EST TUE DEC 11 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
FROM NRN HUDSON BAY INTO THE CNTRL CONUS. WEAK SHORTWAVES MOVING
THROUGH THIS TROUGH HAVE SUPPORTED AREAS OF VERY LIGHT SNOW AND
FLURRIES TODAY. SOUTHERLY CONVERGENT FLOW OFF LAKE MICHIGAN
SUPPORTED A DOMINANT LAKE EFFECT BAND INTO LUCE COUNTY THIS MORNING
AND EARLY AFTERNOON WHICH DROPPED AT LEAST 7 INCHES OF SNOW NEAR
MCMILLAN. THIS BAND HAS SINCE WEAKENED AND MOVED EAST.
MAIN FCST CONCERN TONIGHT IS POSSIBILITY OF MODERATE LAKE EFFECT
SNOW SHOWERS OVER THE NW CWA.
TONIGHT...THE NW ONTARIO TROUGH WILL MOVE EAST AND DRAG A COLD
FRONT INTO WRN LAKE SUPERIOR. THE COLDER AIR ALONG WITH WINDS
VEERING WRLY WILL PROVIDE FAVORABLE CONDITIONS FOR LES INTO THE
KEWEENAW. WITH 850 MB TEMPS DROPPING TO AROUND -15C...INVERSION
HEIGHTS AOA 7K FT...AND LOW LEVEL CONVERGENCE STRENGTHENING DOWNWIND
FROM THE APOSTLE ISLANDS...A MODERATE TO POSSIBLE HEAVY LES BAND IS
EXPECTED TO DEVELOP. SNOWFALL AMOUNTS OF AT LEAST 2 TO 5 INCHES ARE
POSSIBLE...ESPECIALLY IN THE HIGHER TERRAIN FROM TWIN LAKES TO
CALUMET. SINCE MODELS ARE IN FAIRLY GOOD AGREEMENT THAT A HEAVIER
BAND WILL SET UP OVER THIS AREA...HAVE ELECTED TO GO WITH AN
ADVISORY FOR NORTHERN HOUGHTON COUNTY. THERE IS STILL TOO MUCH
UNCERTAINTY TO INCLUDE KEWEENAW OR ONTONAGON IN AN ADVISORY AT THIS
TIME AS IT LOOKS LIKE THEY MAY BE ON THE FRINGE OF WHERE THE HEAVIER
SNOW BAND WILL SET UP. MODEL SNDGS INDICATE SUBSIDENCE WITH QUICKLY
LOWERING INVERSION HEIGHTS AFTER MIDNIGHT SO EXPECT DIMINISHING LES
INTENSITY BY THAT TIME. COLDEST TEMPS TONIGHT SHOULD BE ALONG THE
WISCONSIN BORDER WHERE SINGLE DIGITS COULD BE REACHED UNDER LIGHT
WINDS AND CLEARING SKIES OF SFC RDG. ELSEWHERE EXPECT LOWS TO BE
GENERALLY IN THE TEENS.
WEDNESDAY...THERE COULD BE SOME LINGERING LES OVER THE KEWEENAW
EARLY IN THE DAY BUT OTHERWISE SUBSIDENCE/DRYING AND LOWERING
INVERSION ALONG WITH QUICKLY BACKING FLOW SHOULD QUICKLY END LES.
SHORTWAVE QUICKLY MOVING ACROSS THE US/CANADIAN BORDER LATE IN THE
DAY MAY BRUSH THE NW PART OF LAKE SUPERIOR WITH LIGHT SNOW/FLURRIES
BUT OTHERWISE FORCING INDICATES BETTER CHC OF SNOW WILL STAY NORTH
AND WEST OF THE CWA. INCREASING H925 WINDS TO 35-45 KTS LATE IN
THE DAY ALONG WITH NEUTRAL TO SLIGHLY UNSTABLE TEMPERATURE PROFILE
FM SFC-H9 AND INCREASING PRESSURE FALLS OVR LK SUPERIOR AND INTO
ONTARIO MAY RESULT IN AREAS NEAR LK SUPERIOR OVR NCNTRL AREAS TO
GUST AOA 30 MPH TOWARD EVENING. EXPECT HIGHS IN THE UPR 20S AND
LOWER 30S.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 424 PM EST TUE DEC 11 2012
JET STREAK WILL BE PUSHING THROUGH THE NEARLY ZONAL NORTHERN FLOW AT
THE START OF THE PERIOD. THE LEFT FRONT OF THIS 110KT STREAK WILL BE
OVER UPPER MICHIGAN AND AIDING A WEAK 1012MB SFC LOW TRACKING ALONG
THE WARM FRONT ON WEDNESDAY NIGHT. FAIRLY DRY SURFACE TO H850 LAYER
OVER MUCH OF THE LAND CWA...SO DON/T THINK THERE WOULD BE MUCH SNOW
HITTING THE SURFACE EVEN WITH THE STRONG WAA ALOFT. THUS...WILL
LIMIT THE EVENING SLIGHT CHANCES TO THE TIP OF THE KEWEENAW
PENINSULA WITH THE CHANCES OVER NORTHERN LAKE SUPERIOR. THIS FORCING
WILL SHIFT EAST DURING THE OVERNIGHT HOURS AND FOLLOW THE LOW INTO
ONTARIO.
BEFORE THE LOW DEPARTS THERE WILL BE STRONG WINDS ALOFT...ESPECIALLY
ABOVE THE INVERSION WHERE H900 WINDS APPROACH 45-50KTS ON WEDNESDAY
EVENING. BUT BELOW THE INVERSION WINDS ARE LIGHTER AND ONLY APPROACH
30-35KTS. AREA OF HIGHER PRESSURE FALLS OVER THE NORTHERN LAKE
INDICATES THE POTENTIAL FOR GUSTY WINDS ON WEDNESDAY EVENING. WITH
IT OCCURRING AT NIGHT...EXPECT THE SUSTAINED WINDS TO BE
HIGHER...BUT THE GUSTS MORE OCCASIONAL AND THE STRONGEST OVER THE
DOWNSLOPE AREAS OF THE NORTH CENTRAL. LOW LEVEL JET DIMINISHES
THROUGH THE NIGHT WITH THE LOW SHIFTING TO THE NORTHEAST AND EXPECT
THE SURFACE WINDS TO FOLLOW SUIT. THESE NIGHT TIME STRONG LOW LEVEL
JET ABOVE AN INVERSION ARE ALWAYS DIFFICULT TO DETERMINE THE AMOUNT
OF WIND THAT WILL MAKE IT TO THE SURFACE. BUFKIT MOMENTUM TRANSFER
IS USUALLY DECENT AT APPROXIMATE SUSTAINED WINDS/GUSTS...AND BOTH
NAM/GFS SOUNDINGS FOR STDM4 AND EAST BUOY ONLY SHOW A 6HR PERIOD
WEDNESDAY EVENING OF 30-35KTS. WILL LEAVE THE GALE WATCH AS
IS...SINCE HIGHER PLATFORMS WILL LIKELY SEE SOME OF THESE WINDS.
AREA WILL BE SOUTH OF THE TRAILING SURFACE TROUGH ON THURSDAY AND
EXPECT AN ABOVE NORMAL DAY OVER UPPER MICHIGAN. REMAINING
SOUTHERLY FLOW AND A FEW BREAKS IN THE MID CLOUDS SHOULD LEAD
TO ALL OF THE AREAS RISING ABOVE FREEZING DURING THE DAY.
MODELS HAVE THE IDEA OF THE TROUGH SAGGING SOUTH OVER SOUTHERN LAKE
SUPERIOR THURSDAY AFTERNOON AND REMAINING IN PLACE INTO FRIDAY
EVENING. THIS IS IN RESPONSE TO A SHORTWAVE THAT STREAKS THROUGH
THE ZONAL FLOW ON THURSDAY. AS THE TROUGH TRIES TO SAG SOUTH...LOW
LEVEL MOISTURE WILL INCREASE ON THE NORTH SIDE OF IT...BUT THERE IS
LITTLE TO NO CONVERGENCE ALONG THE TROUGH TO SUPPORT PRECIPITATION.
THUS...THE MAIN FORCING MECHANISM COMES FROM UPSLOPE FLOW. WITH THIS
SURFACE TROUGH STALLING OVER THE AREA...THE LOW LEVEL FLOW IS VERY
COMPLICATED AND UNCERTAIN AND MAKES PINPOINTING THE LIGHT
PRECIPITATION VERY DIFFICULT. SINCE THE TOP OF THE CLOUDS ARE
AROUND -8C AT 4KFT...DON/T EXPECT THERE TO BE MANY ICE CRYSTALS
IN THE CLOUDS AND REMOVE THE SNOW MENTION AND JUST GO WITH
DRIZZLE OR FREEZING DRIZZLE. LIGHT WESTERLY FLOW WOULD
FAVOR IT TO BE MAINLY OVER THE KEWEENAW ON THURSDAY AFTERNOON.
AFTER THAT...THERE ARE NO STRONG INDICATIONS ON WIND DIRECTIONS AND
WILL KEEP IT HIGHLIGHTED TO THE KEWEENAW FOR MUCH OF THE PERIOD
SINCE THEY WOULD HAVE MORE OPPORTUNITIES WITH THE VARIED WIND
DIRECTIONS. IN ADDITION...PICKED OUT A FEW LOCALIZED AREAS IN THE
NORTH CENTRAL TO HIGHLIGHT A SLIGHT CHANCE OF FREEZING
DRIZZLE BASED ON CONSENSUS WIND DIRECTIONS.
MODELS IN MUCH BETTER AGREEMENT THAN YESTERDAY HEADING INTO THE
WEEKEND...WITH THE GFS SHIFTING TOWARDS THE ECMWF/UKMET/GEM
SOLUTION. BUT...WITH THE INTERACTION OF SEVERAL DIFFERENT WAVES BY
THE TIME IT GETS HERE LEADS TO SOME UNCERTAINTY. THAT BEING
SAID...WITH THE CONSISTENCY OF THE ECMWF OVER THE LAST COUPLE DAYS
AND IT/S SUPERIOR SATELLITE BASED INITIALIZATION...WOULD WANT TO
LEAN TOWARDS THAT IDEA. WITH THE CURRENT TRACK...MUCH OF THE CWA
WILL SEE MEASURABLE...BUT LIGHT SNOW DUE TO THE BROAD AREA OF
CIRCULATION. BEST CHANCES WILL BE OVER THE SOUTHEAST HALF OF THE
CWA AND CLOSER TO THE LOW TRACK AND ALSO OVER NORTH CENTRAL UPPER
MICHIGAN WHERE UPSLOPE FLOW MAY INCREASE AMOUNTS. WITH THE ZONAL
FLOW IN PLACE AHEAD OF THIS WAVE...THERE WON/T BE MUCH COLD AIR TO
WORK WITH AND THAT LIMITS ANY LAKE ENHANCED POTENTIAL DURING THE
SYSTEM AND ALSO ON THE BACKSIDE. 12Z ECMWF HAS COME IN WITH A SLIGHT
SHIFT TO THE NORTH WITH THE LOW...SO FUTURE SHIFTS WILL HAVE TO
MONITOR IF THIS TREND CONTINUES.
FORECAST BECOMES MORE UNCERTAIN FOR MONDAY/TUESDAY OF NEXT
WEEK...WITH THE 00Z ECMWF HOLDING THE UPPER TROUGH OVER THE UPPER
GREAT LAKES REGION AND THE GFS AND IT/S ENSEMBLE PUSHING THE WAVE
OFF TO THE NEW ENGLAND STATES. 12Z ECMWF HAS TRENDED MORE
PROGRESSIVE...SO THERE COULD BE LIGHT LES OFF LAKE SUPERIOR MONDAY
AND TUESDAY AND SLIGHT CHANCE POPS REPRESENTS THAT WELL AT THIS
POINT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 109 PM EST TUE DEC 11 2012
LOOKING UPSTREAM OVER NRN WI/NRN MN WOULD EXPECT CIGS AT OR SLIGHTLY
ABOVE MVFR MOST OF THE DAY WITH INCREASING SW FLOW AHEAD OF AN
APPROACHING TROUGH. FOLLOWING THE TROF PASSAGE AND WIND SHIFT TO THE
W IN THE EARLY EVNG...EXPECT SHSN TO IMPACT THE EXPOSED KEWEENAW
PENINSULA...WITH IFR OR LIFR CONDITIONS LIKELY AT CMX. DOWNSLOPE
NATURE OF W WIND BEHIND THIS TROF PASSAGE WL LIKELY RESULT IN VFR
CIGS AT SAW BY EARLY EVENING. WINDS BACKING SW AGAIN BY WED MORNING
SHOULD LEAD TO VFR CONDITIONS AT ALL SITES.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 424 PM EST TUE DEC 11 2012
SOUTHWEST WINDS TO 25 KTS WILL SHIFT WESTERLY THIS EVENING AS A
TROUGH MOVES THROUGH THE AREA AND THEN DIMINISH BRIEFLY BLO 20 KNOTS
LATE TONIGHT INTO WED MORNING. EXPECT INCREASING SOUTH TO SOUTHWEST
WINDS LATE WEDNESDAY INTO WEDNESDAY NIGHT. MARGINAL GALES TO 35
KNOTS ARE POSSIBLE OVER EASTERN PORTIONS OF LAKE SUPERIOR SO WILL
KEEP GALE WATCH IN EFFECT. A WEAK TROUGH DROPS ACROSS THE LAKE BY
THURSDAY EVENING. WINDS WILL DIMINISH SIGNIFICANTLY THURSDAY NIGHT
INTO FRIDAY IN THE WAKE OF THIS TROUGH. A LOW PRESSURE SYSTEM
DEVELOPING IN THE PLAINS PUSHES INTO WESTERN GREAT LAKES LATE
SATURDAY INTO SUNDAY WHILE HIGH PRESSURE MOVES ACROSS NEW ENGLAND.
WINDS SHOULD INCREASE FROM THE EAST ON SATURDAY OVER LAKE SUPERIOR.
SINCE EXACT TRACK AND DEPTH OF SFC LOW REMAINS UNCERTAIN AT THIS
TIME...WILL KEEP WINDS SUB-GALE FOR NOW.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST WEDNESDAY FOR MIZ003.
LAKE SUPERIOR...
GALE WATCH FROM WEDNESDAY EVENING THROUGH LATE WEDNESDAY NIGHT
FOR LSZ265>267.
LAKE MICHIGAN...
GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY MORNING FOR
LMZ248-250.
&&
$$
SHORT TERM...VOSS
LONG TERM...SRF
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
110 PM EST TUE DEC 11 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 545 AM EST TUE DEC 11 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
FROM NRN HUDSON BAY INTO THE CNTRL CONUS. WEAK SHORTWAVE TROUGHS
FROM CNTRL UPPER MI INTO ERN WI AND OVER MN SUPPORTED AREAS OF VERY
LIGHT SNOW AND FLURRIES. ALTHOUGH RADARS SHOWED DECENT COVERAGE WITH
WEAK RETURNS...OBS INDICATED UPSTREAM VISIBILITIES WERE GENERALLY
AOA 6SM. AT THE SFC...SRLY WINDS WERE INCREASING OVER THE REGION
AHEAD OF TROUGH THAT EXTENDED FROM NW ONTARIO INTO MN.
WITH LIGHT WINDS OVER LAKE MICHIGAN AND LAND BREEZES BECOMING MORE
PROMINENT...MID LAKE LES HAD DEVELOPED OFFSHORE FROM NW LOWER MI.
MAIN FCST CONCERNS ARE LAKE EFFECT SNOW TRENDS/AMOUNTS OFF OF LAKE
MICHIGAN TODAY AND INTO THE KEWEENAW TONIGHT.
TODAY...AS THE MOISTURE AND LIGHT PCPN ASSOCIATED WITH THE SHRTWVS
ADVANCE TO THE EAST AND CONVERGENT SRLY FLOW INCREASES ACROSS LAKE
MICHIGAN...MDLS SUGGEST THAT A DOMINANT LES BAND IS LIKELY TO
DEVELOP. THE HIGH RES MODELS CONSENSUS ALSO INDICATE THAT THE BAND WOULD
LIKELY MOVE ONSHORE EAST OF ISQ AND SPREAD QUICKLY TO THE NORTH AND
EAST INTO LUCE COUNTY BY MID MORNING. ALTHOUGH CONFIDENCE IS HIGH
THAT A BAND WILL MOVE INTO EASTERN UPPER MICHIGAN...THERE IS STILL
UNCERTAINTY WITH THE DETAILS OF TIMING/LOCATION OF THE BAND. WITH A
LONG FETCH ACROSS THE LAKE...AND MODERATE INSTABILITY (850 MB TEMP
OF -11C AND LAKE SFC NEAR 6C)...MODERATE TO STRONG CONV...AND
INVERSION HEIGHTS TO AROUND 10K FT...SNOWFALL INTENSITY SHOULD
BECOME HEAVY AT TIMES. EVEN IF 1-2 INCH PER HOUR SNOWFALL RATES
DEVELOP...THE STEADY EASTWARD PROGRESSION SHOULD LIMIT LCL MAX SNOW
AMOUNTS TO AROUND 4 INCHES. SO...AN LES ADVY WAS POSTED FOR SRN
SCHOOLCRAFT AND LUCE COUNTIES.
OTHERWISE...THE BEST CHANCE FOR ADDITIONAL FLURRIES OR LIGHT SNOW
SHOWERS THIS AFTERNOON WILL BE OVER THE WRN CWA AS YET ANOTHER WEAK
SHRTWV MOVES FROM WRN MN MOVES TOWARD THE AREA.
TONIGHT...THE NW ONTARIO TROUGH WILL MOVE TO THE EAST DRAGGING A
COLD FRONT INTO WRN LAKE SUPERIOR. THE COLDER AIR ALONG WITH WINDS
VEERING WRLY WILL PROVIDE FAVORABLE CONDITIONS FOR LES INTO THE
KEWEENAW. WITH 850 MB TEMPS DROPPING TO AROUND -14C...INVERSION
HEIGHTS AROUND 7K FT...AND LOW LEVEL CONVERGENCE STRENGTHENING
DOWNWIND FROM THE APOSTLE ISLANDS...A MODERATE TO HEAVY LES BAND IS
EXPECTED TO DEVELOP. SNOWFALL AMOUNTS OF AT LEAST 2 TO 4 INCHES ARE
LIKELY...ESPECIALLY IN THE HIGHER TERRAIN FROM TWIN LAKES TO CALUMET.
SINCE THERE STILL IS UNCERTAINTY WITH THE DURATION AND LOCATION OF
THE MAIN LES BAND(S)...NO HEADLINE WAS ISSUED AT THIS TIME.
SUBSIDENCE WITH QUICKLY LOWERING INVERSION HEIGHTS AND DIMINISHING
LES INTENSITY IS EXPECTED AFTER MIDNIGHT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 545 AM EST TUE DEC 11 2012
AS STRONG H3 JET REFOCUSES OVER EASTERN SEABOARD BY THURSDAY...
EXPECT AMPLIFIED TROUGHING CURRENTLY IN PLACE OVER MUCH OF CONUS
TO TRANSITION TO SPLIT ZONAL FLOW. NORTHERN PLAINS AND UPPER GREAT
LAKES WILL BE AFFECTED BY NORTHERN STREAM THROUGH REST OF THE WORK
WEEK. DISTURBANCES IN THE NORTHERN STREAM NOT FORECAST TO BE ALL
THAT STRONG AND SINCE MAJORITY THE ENERGY FROM STRONGER SHORTWAVES
STAYS MORE OVER CANADA...EXPECT ONLY MINOR IMPACT TO SENSIBLE WX OVR
LAKE SUPERIOR AND UPR MICHIGAN.
A BIT OF LK EFFECT SNOW TO CONTEND WITH OVER THE KEWEENAW TO OPEN
THE LONG TERM PERIOD ON WEDNESDAY MORNING. KEPT 20 POPS IN THROUGH
MID MORNING...BUT THE SUBSIDENCE/DRYING AOA 850MB/LOWERING INVERSION
AND QUICKLY BACKING BLYR FLOW WILL END ANY WHATEVER LK EFFECT
LINGERS PAST 12Z IN SHORT ORDER. ATTN THEN TURNS TO LEAD WAVE
ZIPPING ALONG US/CANADIAN BORDER LATER WEDNESDAY IN INCREASINGLY
ZONAL FLOW. LARGER SCALE DYNAMICS WITH THE WAVE /H7-H5 Q-VECTOR
CONVERGENCE AND LEFT EXIT REGION JET FORCING/ STAYS MOSTLY OVER
ONTARIO WEDNESDAY AFTN AND WEDNESDAY NIGHT. ONLY MODELS THAT GRAZE
NORTHERN CWA /KEWEENAW AND LUCE COUNTY/ WITH QPF ARE THE 00Z
CANADIAN GEM-NH AND UKMET. OTHER MODELS ARE QUITE DRY BLO THE CLOUD
BASE AROUND H7...SO IT TAKES UNTIL PARCELS REACH OVER NORTHERN LK
SUPERIOR/NORTHERN ONTARIO TO SATURATE/PRECIPITATE. DID NOT WANT TO
COMPLETELY IGNORE GEM-NH AND UKMET...BUT KEPT POPS IN THE FAR NORTH
NO MORE THAN 20 PCT. BEGINNING TO THINK THAT INSTEAD OF PRECIP THAT
GUSTY SW WINDS AND STEADY TEMPS IN THE UPR 20S TO MID 30S MAY BE
MAIN PRIMARY RESULT FROM THIS INITIAL WAVE. H925-H85 WINDS 35-45 KTS
ALONG WITH NEUTRAL TO SLIGHLY UNSTABLE TEMPERATURE PROFILE SFC-H9
ALONG WITH PRESSURE FALLS OVR LK SUPERIOR AND INTO ONTARIO MAY
RESULT IN AREAS NEAR LK SUPERIOR OVR NCNTRL UPR MICHIGAN...NEAR LK
MICHIGAN AND OVER MUCH OF EASTERN CWA GUSTING SEEING WINDS GUSTING
20-35 MPH THROUGH THE NIGHT WITH MINIMAL TEMP FALL. WENT WITH
NON-DIURNAL TEMP TREND TO COVER THIS POSSIBILITY.
LEAD WAVE HEADS TOWARD QUEBEC BY DAYBREAK THURSDAY AS SFC TROUGH
EASES ACROSS LK SUPERIOR/NORTHERN UPR MICHIGAN. ANOTHER WAVE IS
LURKING UPSTREAM IN THE QUICK ZONAL FLOW ALOFT. UKMET/GEM-NH
STRONGEST WITH WAVE...GFS/ECMWF NOT SO MUCH. SINCE THE LOW-LEVEL
TROUGH BECOMES PARALLEL WITH UPPER FLOW...NOT TOO KEEN ON PUSHING
TROUGH AS FAR SOUTH AS GEM-NH HAS IT BY THURSDAY AFTN. INSTEAD KEPT
BOUNDARY HUNG UP OVR KEWEENAW WITH JUST A SMALL CHANCE OF SNOW
SHOWERS BY AFTN AS SHALLOW COLD AIR TRIES TO SETTLE BACK ACROSS
NORTHERN CWA. TEMPS AHEAD OF FRONT...WHEREVER IT ENDS UP...COULD
GET FAIRLY WARM WITH READINGS WELL INTO THE 30S...ESPECIALLY EAST.
FOR THURSDAY NIGHT INTO FRIDAY...MAY BE SETTING UP FOR ANOTHER
DZ/FZDZ OR SNOW SCENARIO. GFS IS COLDER...BUT GFS/ECMWF/GEM-NHEM
INDICATE H85 TEMPS BORDERLINE TO GET ICE NUCLEATION/SNOW. ALSO GFS
AND ECMWF INDICATE A LOT OF LOW-LEVEL MOISTURE BUT NOT AS MUCH H85
MOISTURE. INTRODUCED SOME DZ/FZDZ FOR FRIDAY AND FRIDAY NIGHT
BETWEEN THE TROUGH THAT DROPS THROUGH LATE THURSDAY AND OUT AHEAD
OF STRONGER LOW PRESSURE SYSTEM MOVING INTO REGION NEXT WEEKEND.
UPSLOPE NE THEN SE WINDS WOULD ONLY HELP OUT THE DZ/FZDZ.
AS FLOW BECOMES SPLIT LATE THIS WEEK...STRONG SOUTHERN STREAM WAVE
TAKES SHAPE OVER DESERT SOUTHWEST. IT IS THIS WAVE THAT BECOMES MAIN
INSTIGATOR FOR LEE ROCKIES CYCLOGENESIS LATE FRIDAY INTO SATURDAY.
THIS SOUTHERN STREAM WAVE/ASSOCIATED SFC LOW ARE FORECAST TO EJECT
OUT OF SOUTHERN PLAINS INTO WESTERN GREAT LAKES OR OHIO VALLEY TO
END THE WEEKEND. FLOW PATTERN BECOMES QUITE MESSY THOUGH AS ANOTHER
WAVE WILL BE QUICKLY FOLLOWING INTO SOUTHERN PLAINS AND THERE IS
EVEN A WAVE IN THE NORTHERN STREAM THAT WILL TRY TO MAKE A RUN INTO
THE NORTHERN PLAINS...THOUGH IT DOES SEEM AT LEAST AT THIS POINT...
THAT THAT WAVE MAY GET DEFLECTED OFF INTO CANADA AWAY FROM THE FRAY.
ALL THE WAVES PROBABLY WILL END UP INTERACTING WITH EACH OTHER IN
SOME FORM OR ANOTHER. NET RESULT IS A NOT SO CLEAR CUT FORECAST OF
THE SFC LOW/THERMAL PROFILE/PRECIPITATION COVERAGE AND INTENSITY
ACROSS UPPER LAKES REGION LATER SATURDAY INTO SUNDAY. ONLY REAL
MODEL TREND OF NOTE IS GFS HAS TRENDED TOWARD ECMWF IDEA OF A MORE
CLOSED OFF SOUTHERN STREAM/SFC LOW SINCE THE 18Z RUN ON MONDAY AFTN.
TROUBLE IS THAT THIS WAVE IS STILL OVER GULF OF ALASKA THIS MORNING
AND REALLY WILL NOT BE ONSHORE OVER CONUS FOR BETTER ROAB SAMPLING
UNTIL LIKELY FRIDAY MORNING AT THE EARLIEST. EXPECT UNCERTAINTY TO
CLOUD THE FORECAST UNTIL THAT POINT WITH THE SPECIFICS OF THE TRACK
OF SFC LOW. A CONSENSUS WAS RETAINED FOR POPS NOW. FOR OVERALL PTYPE
LEANED ON LARGE SCALE THICKNESSES...THOUGH WHERE FLOW WAS ONSHORE
OFF THE GREAT LAKES...KEPT SOME MENTION OF RAIN AS WELL WITH TEMPS
EXPECTED TO BE IN THE MID 30S. LINGERED CHANCE POPS FOR MAINLY SNOW
OVER THE EAST ON SUNDAY. NOT A LOT OF COLD AIR FCST TO BE AROUND IN
WAKE OF THE MAINLY SOUTHERN STREAM ORIGIN SYSTEM...SO KEPT POPS FOR
ANY LK EFFECT INTO MONDAY ON THE LOW SIDE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 109 PM EST TUE DEC 11 2012
LOOKING UPSTREAM OVER NRN WI/NRN MN WOULD EXPECT CIGS AT OR SLIGHTLY
ABOVE MVFR MOST OF THE DAY WITH INCREASING SW FLOW AHEAD OF AN
APPROACHING TROUGH. FOLLOWING THE TROF PASSAGE AND WIND SHIFT TO THE
W IN THE EARLY EVNG...EXPECT SHSN TO IMPACT THE EXPOSED KEWEENAW
PENINSULA...WITH IFR OR LIFR CONDITIONS LIKELY AT CMX. DOWNSLOPE
NATURE OF W WIND BEHIND THIS TROF PASSAGE WL LIKELY RESULT IN VFR
CIGS AT SAW BY EARLY EVENING. WINDS BACKING SW AGAIN BY WED MORNING
SHOULD LEAD TO VFR CONDITIONS AT ALL SITES.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 545 AM EST TUE DEC 11 2012
WINDS 25 KTS OR BLO THROUGH MIDDAY WEDNESDAY THEN EXPECT INCREASING
SOUTH TO SOUTHWEST WINDS LATE WEDNESDAY/WEDNESDAY NIGHT AND INTO
EARLY THURSDAY MORNING. GALES LIKELY OVER EASTERN PORTIONS OF LAKE
SUPERIOR SO HAVE ISSUED GALE WATCH. TROUGH DROPS ACROSS THE LAKE BY
THURSDAY EVENING. WINDS WILL DIMINISH SIGNIFICANTLY THURSDAY NIGHT
INTO FRIDAY IN WAKE OF THIS TROUGH. LOW PRESSURE SYSTEM DEVELOPING
IN THE PLAINS PUSHES INTO WESTERN GREAT LAKES LATE SATURDAY INTO
SUNDAY WHILE HIGH PRESSURE MOVES ACROSS NEW ENGLAND. WINDS SHOULD
INCREASE FROM THE EAST ON SATURDAY OVER LAKE SUPERIOR. EXACT TRACK
AND DEPTH OF SFC LOW REMAINS UNCERTAIN THOUGH...SO DID NOT GO STRONG
ON WINDS AT THIS TIME. POSSIBLE THAT WINDS MAY EVENTUALLY NEED TO BE
INCREASED COMPARED TO WHAT IS IN THE CURRENT FORECAST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR
MIZ007.
LAKE SUPERIOR...
GALE WATCH FROM WEDNESDAY EVENING THROUGH LATE WEDNESDAY NIGHT
FOR LSZ265>267.
LAKE MICHIGAN...
GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY MORNING FOR
LMZ248-250.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...VOSS
MARINE...JLA
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1253 PM EST TUE DEC 11 2012
.AVIATION...
//DISCUSSION...
DAYTIME HEATING AND MOISTURE FROM FLOW OFF LAKE MICHIGAN ARE BEING
AIDED BY A WEAK UPPER LEVEL DISTURBANCE PASSING THROUGH THE
AREA...AND ARE ALLOWING FOR THE DEVELOPMENT OF AN MVFR STRATOCU
DECK. THIS DECK SHOULD BREAK IN THE EARLY EVENING AS THE WAVE
PASSES...AND AS WE LOSE DIURNAL INFLUENCES.
FLOW WILL TURN MORE WESTERLY OFF THE GREAT LAKES TONIGHT...BECOMING
MORE FAVORABLE FOR LAKE EFFECT CLOUDS TO STREAM INLAND ONCE AGAIN.
EXPECT MVFR TO LOW VFR CEILING TO FILL IN LATE...STARTING AT MBS AND
WORKING SOUTH BEFORE DAYBREAK. THIS DECK SHOULD THEN MIX BACK OUT
EARLY WEDNESDAY AFTERNOON AS FLOW TURNS MORE SOUTHERLY.
FOR DTW... BKN CEILINGS BETWEEN 2500 AND 3000 FEET WILL PREVAIL
THROUGH THE REMAINDER OF THE AFTERNOON AND INTO THE EARLY EVENING
(UNTIL ABOUT 22-23Z)...BEFORE DAYTIME HEATING CEASES AND THE DECK IS
ALLOWED TO BREAK UP. MOSTLY CLEAR CONDITIONS WILL THEN LAST UNTIL
CLOSE TO SUNRISE WEDNESDAY WHEN PATCHES OF VFR STRATOCU BELOW 5000
FEET WILL AGAIN BE POSSIBLE FROM AS LAKE EFFECT CLOUDS DEVELOP FROM
OFF LAKE MICHIGAN.
//DTW THRESHOLD THREATS...
* MODERATE CONFIDENCE IN TIMING AND COVERAGE OF CEILING BELOW 5000
TODAY AND LATE TONIGHT.
&&
.PREV DISCUSSION...ISSUED 349 AM EST TUE DEC 11 2012
SHORT TERM... TODAY AND TONIGHT
COMPLEXITIES IN THE FORECAST FOR TODAY INCLUDE EVOLUTION OF LAKE
EFFECT SNOW NEAR THE LAKE HURON SHORELINE DURING THE MORNING ALONG
WITH INLAND CLOUD COVERAGE THROUGHOUT THE DAY.
EARLY MORNING OBSERVATIONS FROM THE CANADIAN RADAR IN EXETER
INDICATE A BAND OF LAKE EFFECT SNOW PERCOLATING OVER THE SOUTH HALF
OF LAKE HURON WITHIN THE INCREASINGLY CONVERGENT LAKE INDUCED
SURFACE TROUGH. MODEL DEPICTIONS OF 850 MB TEMPERATURE SUGGEST
INSTABILITY IS ALREADY MORE THAN ADEQUATE WITH DELTA-T AVERAGING 18C
OVER THE SOUTH HALF OF THE LAKE. THE SOMEWHAT MUTED CONVECTION
DURING THE EARLY MORNING IS LIKELY A RESULT OF MID LEVEL SUBSIDENCE
INDICATED IN WATER VAPOR IMAGERY ON THE HEELS OF THE SHEAR AXIS
DEPARTING TO THE EAST. THIS IS EXPECTED TO CHANGE AS A SMALL BUT
SUFFICIENTLY STRONG SHORT WAVE SLIDES THROUGH LOWER MICHIGAN TOWARD
SUNRISE. THIS FEATURE HELPED SUPPORT A STRONG LAKE EFFECT BAND OVER
SOUTHERN LAKE MICHIGAN DURING THE NIGHT WITH CONVECTION DEEP ENOUGH
FOR SNOW SHOWERS TO REACH NORTHWEST OHIO. AS THE WAVE MOVES TOWARD
LAKE HURON DURING THE REST OF THE MORNING, IT IS EXPECTED TO BOOST
THE CIRCULATION WITHIN THE LAKE TROUGH AND HELP FLARE UP LAKE EFFECT
SNOW THERE AS WELL BEFORE QUICKLY SLIDING EASTWARD BY LATE MORNING.
AS THE WAVE APPROACHES, IT IS EXPECTED TO DRAW THE LAKE TROUGH
TOWARD THE SHORELINE OF THE THUMB FOR A FEW HOURS AROUND SUNRISE
BEFORE THE PASSAGE OF THE LARGE SCALE SURFACE RIDGE BACKS THE LOW
LEVEL FLOW TOWARD THE SOUTHWEST. MODIFIED RAP MODEL SOUNDINGS
INDICATE LAKE INDUCED CAPE APPROACHING 500 J/KG AND EQUILIBRIUM
LEVEL PUSHING 10 KFT BY 12Z, INGREDIENTS FOR HEAVY LAKE EFFECT SNOW
SHOWERS, BUT A LATE START AND SHORT DURATION WILL BE THE LIMITING
FACTORS IN SUPPORT OF A 1 TO 2 INCH FORECAST.
ELSEWHERE AROUND SE MICHIGAN, THE NORTHERLY LOW LEVEL FLOW HAS
BECOME JUST NEUTRAL ENOUGH TO ALLOW FOR SOME BREAKS IN THE STRATUS
DURING THE EARLY MORNING. EXPECT THIS WILL CONTINUE THROUGH LATE
MORNING BUT IN A RANDOM FASHION THAT WILL PROVIDE INTERVALS OF
PARTLY SUNNY CONDITIONS THROUGH CENTRAL PORTIONS OF LOWER MICHIGAN.
THE BACKING LOW LEVEL FLOW WILL THEN DIRECT CLOUDS, AND PERHAPS EVEN
A FEW SNOW SHOWERS, EASTWARD FROM LAKE MICHIGAN AS PART OF A LARGER
AREA OF STRATUS COVERING THE WESTERN GREAT LAKES. THE EXTRA CLOUD
COVER COMBINED WITH LATE DEVELOPING SOUTHWEST SURFACE WIND WILL
CONFINE MAX TEMPS TO THE LOWER AND MID 30S TODAY. THE SOUTHWEST FLOW
WILL CARRY IN DRY AIR FROM THE MID MISSISSIPPI VALLEY BY TONIGHT
WHICH WILL SCOUR OUT THE LOW CLOUDS BUT NOT RESULT IN MUCH WARMING.
THE INCREASED GRADIENT FLOW WILL BATTLE THE TENDENCY FOR SURFACE
WIND DECOUPLING AND RESULTANT RADIATIONAL COOLING FOR LOWS DROPPING
BACK INTO THE LOWER TO MID 20S.
LONG TERM...WEDNESDAY THROUGH MONDAY
VERY LITTLE TO DISCUSS IN THE WEDNESDAY TO FRIDAY TIMEFRAME. THE MAIN
TROUGH AXIS WILL BE OVER LOWER MICHIGAN AT THE START OF THE
PERIOD...WHICH WILL GIVE WAY TO A GENERAL RISING OF GEOPOTENTIAL
HEIGHTS THROUGH THE END OF THE WORK WEEK. SPLIT FLOW IS STILL
FORECASTED TO DEVELOP WITH THE POLAR JET AXIS REMAINING NORTH OF
LAKES SUPERIOR/HURON ALONG WITH THE PERSISTENCE OF A VERY NOTEWORTHY
SOUTHERN STREAM AXIS. GUIDANCE CAME IN MARKEDLY WARMER FOR WEDNESDAY
AND BOOSTED TEMPERATURES UPWARDS A COUPLE OF DEGREES. DAYTIME HIGHS
ARE EXPECTED TO REACH/CLIMB ABOVE 40 DEGREES FOR BOTH THURSDAY AND
FRIDAY.
A TON OF UNCERTAINTY EXISTS WITH REGARDS TO HOW THIS WEEKEND WILL
PLAY OUT. THE PERTINENT WEATHER ASPECTS WILL COME DOWN TO THE
DETAILS. UNFORTUNATELY...THE MODEL DATA SUGGESTS THAT IT WILL TAKE
UNTIL FRIDAY MORNING BEFORE THE MAIN TROUGH AXIS OF THE IMPORTANT
SHORTWAVE WILL COME ONSHORE OF SOUTHERN CA/BAJA OF MEXICO. THAT IS A
LONG TIME TO WAIT. LATEST TRENDING FOR THE 11.00Z SUITE WAS THAT THE
ECMWF ARRIVED IN MORE AGREEMENT WITH THE GFS SOLUTION. THE GFS HAS
BEEN ADVERTISING THE FIRST DEVELOPED SYSTEM (ARRIVING OVER THE GREAT
LAKES ON SATURDAY) WILL RUN INTO A EASTERN CANADIAN/GREENLAND
BLOCKING RIDGE. THE MODELS SUGGEST THAT WHAT BEGINS AS RATHER CRISP
BAROCLINIC DYNAMICS TURNS MUSHY IN AS LITTLE AS 12 HOURS. THE HIGHER
CONFIDENCE PORTION OF THIS FORECAST IS THE HIGH AMOUNT OF MOISTURE
IN TOW WITH THE SYSTEM. THE LIKELIHOOD OF WIDESPREAD PRECIPITATION
IS HIGH AND WENT AHEAD AND HIKED POPS INTO THE HIGH LIKELY RANGE FOR
SATURDAY AND SATURDAY NIGHT. THE ECMWF BRINGS THE MAIN UPPER LEVEL
PV ANOMALY NORTH OF THE SOO...WHICH SUGGESTS THAT PRECIPITATION TYPE
WILL BE ON THE WARM END OF THE SPECTRUM. THE GFS REMAINS A LITTLE
FARTHER SOUTH WITH THE PV ANOMALY...OVER LOWER MICHIGAN AND IS JUST
ONE OF MANY POINTS OF CONTENTION AMONGST THE SUITE.
MARINE...
WEAK HIGH PRESSURE WILL MOVE QUICKLY THROUGH LAKE HURON AND LOWER
MICHIGAN DURING THE AFTERNOON IN A FAVOR OF THE NEXT LOW PRESSURE
SYSTEM MOVING THROUGH NORTHERN ONTARIO. INCREASING SOUTHWEST WIND
WILL REACH GUSTS TO 30 KNOTS TONIGHT OVER THE OPEN WATERS OF CENTRAL
AND NORTHERN LAKE HURON. THE WIND WILL NOT BE QUITE AS STRONG OVER
SAGINAW BAY BUT STRONG ENOUGH TO BUILD WAVES OVER 4 FEET TONIGHT
THROUGH WEDNESDAY REQUIRING A SMALL CRAFT ADVISORY THERE. A LARGER
SYSTEM IS THEN EXPECTED TO TRACK THROUGH NORTHERN ONTARIO AS WELL
DURING WEDNESDAY NIGHT INTO THURSDAY THAT WILL MAINTAIN SOUTHWEST
WIND OVER THE LAKES AND BRING WARMER AIR OVER THE WATER. THE
INCREASED STABILITY BY THIS TIME WILL LIMIT GUST POTENTIAL TO 30
KNOTS OR LESS THROUGH THURSDAY BEFORE THE TRAILING COLD FRONT
SETTLES OVER THE REGION BY FRIDAY. THE FRONT WILL STALL OVER THE
CENTRAL LAKES AS A STRONG LOW PRESSURE SYSTEM TAKES SHAPE OVER THE
PLAINS STATES AND MOVES INTO THE GREAT LAKES DURING THE WEEKEND.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS
FROM PORT AUSTIN TO HARBOR BEACH...FROM 7 PM TUESDAY TO 4 PM
WEDNESDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....HLO
SHORT TERM...BT
LONG TERM....CB
MARINE.......BT
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
714 AM EST TUE DEC 11 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 545 AM EST TUE DEC 11 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
FROM NRN HUDSON BAY INTO THE CNTRL CONUS. WEAK SHORTWAVE TROUGHS
FROM CNTRL UPPER MI INTO ERN WI AND OVER MN SUPPORTED AREAS OF VERY
LIGHT SNOW AND FLURRIES. ALTHOUGH RADARS SHOWED DECENT COVERAGE WITH
WEAK RETURNS...OBS INDICATED UPSTREAM VISIBILITIES WERE GENERALLY
AOA 6SM. AT THE SFC...SRLY WINDS WERE INCREASING OVER THE REGION
AHEAD OF TROUGH THAT EXTENDED FROM NW ONTARIO INTO MN.
WITH LIGHT WINDS OVER LAKE MICHIGAN AND LAND BREEZES BECOMING MORE
PROMINENT...MID LAKE LES HAD DEVELOPED OFFSHORE FROM NW LOWER MI.
MAIN FCST CONCERNS ARE LAKE EFFECT SNOW TRENDS/AMOUNTS OFF OF LAKE
MICHIGAN TODAY AND INTO THE KEWEENAW TONIGHT.
TODAY...AS THE MOISTURE AND LIGHT PCPN ASSOCIATED WITH THE SHRTWVS
ADVANCE TO THE EAST AND CONVERGENT SRLY FLOW INCREASES ACROSS LAKE
MICHIGAN...MDLS SUGGEST THAT A DOMINANT LES BAND IS LIKELY TO
DEVELOP. THE HIGH RES MODELS CONSENSUS ALSO INDICATE THAT THE BAND WOULD
LIKELY MOVE ONSHORE EAST OF ISQ AND SPREAD QUICKLY TO THE NORTH AND
EAST INTO LUCE COUNTY BY MID MORNING. ALTHOUGH CONFIDENCE IS HIGH
THAT A BAND WILL MOVE INTO EASTERN UPPER MICHIGAN...THERE IS STILL
UNCERTAINTY WITH THE DETAILS OF TIMING/LOCATION OF THE BAND. WITH A
LONG FETCH ACROSS THE LAKE...AND MODERATE INSTABILITY (850 MB TEMP
OF -11C AND LAKE SFC NEAR 6C)...MODERATE TO STRONG CONV...AND
INVERSION HEIGHTS TO AROUND 10K FT...SNOWFALL INTENSITY SHOULD
BECOME HEAVY AT TIMES. EVEN IF 1-2 INCH PER HOUR SNOWFALL RATES
DEVELOP...THE STEADY EASTWARD PROGRESSION SHOULD LIMIT LCL MAX SNOW
AMOUNTS TO AROUND 4 INCHES. SO...AN LES ADVY WAS POSTED FOR SRN
SCHOOLCRAFT AND LUCE COUNTIES.
OTHERWISE...THE BEST CHANCE FOR ADDITIONAL FLURRIES OR LIGHT SNOW
SHOWERS THIS AFTERNOON WILL BE OVER THE WRN CWA AS YET ANOTHER WEAK
SHRTWV MOVES FROM WRN MN MOVES TOWARD THE AREA.
TONIGHT...THE NW ONTARIO TROUGH WILL MOVE TO THE EAST DRAGGING A
COLD FRONT INTO WRN LAKE SUPERIOR. THE COLDER AIR ALONG WITH WINDS
VEERING WRLY WILL PROVIDE FAVORABLE CONDITIONS FOR LES INTO THE
KEWEENAW. WITH 850 MB TEMPS DROPPING TO AROUND -14C...INVERSION
HEIGHTS AROUND 7K FT...AND LOW LEVEL CONVERGENCE STRENGTHENING
DOWNWIND FROM THE APOSTLE ISLANDS...A MODERATE TO HEAVY LES BAND IS
EXPECTED TO DEVELOP. SNOWFALL AMOUNTS OF AT LEAST 2 TO 4 INCHES ARE
LIKELY...ESPECIALLY IN THE HIGHER TERRAIN FROM TWIN LAKES TO CALUMET.
SINCE THERE STILL IS UNCERTAINTY WITH THE DURATION AND LOCATION OF
THE MAIN LES BAND(S)...NO HEADLINE WAS ISSUED AT THIS TIME.
SUBSIDENCE WITH QUICKLY LOWERING INVERSION HEIGHTS AND DIMINISHING
LES INTENSITY IS EXPECTED AFTER MIDNIGHT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 545 AM EST TUE DEC 11 2012
AS STRONG H3 JET REFOCUSES OVER EASTERN SEABOARD BY THURSDAY...
EXPECT AMPLIFIED TROUGHING CURRENTLY IN PLACE OVER MUCH OF CONUS
TO TRANSITION TO SPLIT ZONAL FLOW. NORTHERN PLAINS AND UPPER GREAT
LAKES WILL BE AFFECTED BY NORTHERN STREAM THROUGH REST OF THE WORK
WEEK. DISTURBANCES IN THE NORTHERN STREAM NOT FORECAST TO BE ALL
THAT STRONG AND SINCE MAJORITY THE ENERGY FROM STRONGER SHORTWAVES
STAYS MORE OVER CANADA...EXPECT ONLY MINOR IMPACT TO SENSIBLE WX OVR
LAKE SUPERIOR AND UPR MICHIGAN.
A BIT OF LK EFFECT SNOW TO CONTEND WITH OVER THE KEWEENAW TO OPEN
THE LONG TERM PERIOD ON WEDNESDAY MORNING. KEPT 20 POPS IN THROUGH
MID MORNING...BUT THE SUBSIDENCE/DRYING AOA 850MB/LOWERING INVERSION
AND QUICKLY BACKING BLYR FLOW WILL END ANY WHATEVER LK EFFECT
LINGERS PAST 12Z IN SHORT ORDER. ATTN THEN TURNS TO LEAD WAVE
ZIPPING ALONG US/CANADIAN BORDER LATER WEDNESDAY IN INCREASINGLY
ZONAL FLOW. LARGER SCALE DYNAMICS WITH THE WAVE /H7-H5 Q-VECTOR
CONVERGENCE AND LEFT EXIT REGION JET FORCING/ STAYS MOSTLY OVER
ONTARIO WEDNESDAY AFTN AND WEDNESDAY NIGHT. ONLY MODELS THAT GRAZE
NORTHERN CWA /KEWEENAW AND LUCE COUNTY/ WITH QPF ARE THE 00Z
CANADIAN GEM-NH AND UKMET. OTHER MODELS ARE QUITE DRY BLO THE CLOUD
BASE AROUND H7...SO IT TAKES UNTIL PARCELS REACH OVER NORTHERN LK
SUPERIOR/NORTHERN ONTARIO TO SATURATE/PRECIPITATE. DID NOT WANT TO
COMPLETELY IGNORE GEM-NH AND UKMET...BUT KEPT POPS IN THE FAR NORTH
NO MORE THAN 20 PCT. BEGINNING TO THINK THAT INSTEAD OF PRECIP THAT
GUSTY SW WINDS AND STEADY TEMPS IN THE UPR 20S TO MID 30S MAY BE
MAIN PRIMARY RESULT FROM THIS INITIAL WAVE. H925-H85 WINDS 35-45 KTS
ALONG WITH NEUTRAL TO SLIGHLY UNSTABLE TEMPERATURE PROFILE SFC-H9
ALONG WITH PRESSURE FALLS OVR LK SUPERIOR AND INTO ONTARIO MAY
RESULT IN AREAS NEAR LK SUPERIOR OVR NCNTRL UPR MICHIGAN...NEAR LK
MICHIGAN AND OVER MUCH OF EASTERN CWA GUSTING SEEING WINDS GUSTING
20-35 MPH THROUGH THE NIGHT WITH MINIMAL TEMP FALL. WENT WITH
NON-DIURNAL TEMP TREND TO COVER THIS POSSIBILITY.
LEAD WAVE HEADS TOWARD QUEBEC BY DAYBREAK THURSDAY AS SFC TROUGH
EASES ACROSS LK SUPERIOR/NORTHERN UPR MICHIGAN. ANOTHER WAVE IS
LURKING UPSTREAM IN THE QUICK ZONAL FLOW ALOFT. UKMET/GEM-NH
STRONGEST WITH WAVE...GFS/ECMWF NOT SO MUCH. SINCE THE LOW-LEVEL
TROUGH BECOMES PARALLEL WITH UPPER FLOW...NOT TOO KEEN ON PUSHING
TROUGH AS FAR SOUTH AS GEM-NH HAS IT BY THURSDAY AFTN. INSTEAD KEPT
BOUNDARY HUNG UP OVR KEWEENAW WITH JUST A SMALL CHANCE OF SNOW
SHOWERS BY AFTN AS SHALLOW COLD AIR TRIES TO SETTLE BACK ACROSS
NORTHERN CWA. TEMPS AHEAD OF FRONT...WHEREVER IT ENDS UP...COULD
GET FAIRLY WARM WITH READINGS WELL INTO THE 30S...ESPECIALLY EAST.
FOR THURSDAY NIGHT INTO FRIDAY...MAY BE SETTING UP FOR ANOTHER
DZ/FZDZ OR SNOW SCENARIO. GFS IS COLDER...BUT GFS/ECMWF/GEM-NHEM
INDICATE H85 TEMPS BORDERLINE TO GET ICE NUCLEATION/SNOW. ALSO GFS
AND ECMWF INDICATE A LOT OF LOW-LEVEL MOISTURE BUT NOT AS MUCH H85
MOISTURE. INTRODUCED SOME DZ/FZDZ FOR FRIDAY AND FRIDAY NIGHT
BETWEEN THE TROUGH THAT DROPS THROUGH LATE THURSDAY AND OUT AHEAD
OF STRONGER LOW PRESSURE SYSTEM MOVING INTO REGION NEXT WEEKEND.
UPSLOPE NE THEN SE WINDS WOULD ONLY HELP OUT THE DZ/FZDZ.
AS FLOW BECOMES SPLIT LATE THIS WEEK...STRONG SOUTHERN STREAM WAVE
TAKES SHAPE OVER DESERT SOUTHWEST. IT IS THIS WAVE THAT BECOMES MAIN
INSTIGATOR FOR LEE ROCKIES CYCLOGENESIS LATE FRIDAY INTO SATURDAY.
THIS SOUTHERN STREAM WAVE/ASSOCIATED SFC LOW ARE FORECAST TO EJECT
OUT OF SOUTHERN PLAINS INTO WESTERN GREAT LAKES OR OHIO VALLEY TO
END THE WEEKEND. FLOW PATTERN BECOMES QUITE MESSY THOUGH AS ANOTHER
WAVE WILL BE QUICKLY FOLLOWING INTO SOUTHERN PLAINS AND THERE IS
EVEN A WAVE IN THE NORTHERN STREAM THAT WILL TRY TO MAKE A RUN INTO
THE NORTHERN PLAINS...THOUGH IT DOES SEEM AT LEAST AT THIS POINT...
THAT THAT WAVE MAY GET DEFLECTED OFF INTO CANADA AWAY FROM THE FRAY.
ALL THE WAVES PROBABLY WILL END UP INTERACTING WITH EACH OTHER IN
SOME FORM OR ANOTHER. NET RESULT IS A NOT SO CLEAR CUT FORECAST OF
THE SFC LOW/THERMAL PROFILE/PRECIPITATION COVERAGE AND INTENSITY
ACROSS UPPER LAKES REGION LATER SATURDAY INTO SUNDAY. ONLY REAL
MODEL TREND OF NOTE IS GFS HAS TRENDED TOWARD ECMWF IDEA OF A MORE
CLOSED OFF SOUTHERN STREAM/SFC LOW SINCE THE 18Z RUN ON MONDAY AFTN.
TROUBLE IS THAT THIS WAVE IS STILL OVER GULF OF ALASKA THIS MORNING
AND REALLY WILL NOT BE ONSHORE OVER CONUS FOR BETTER ROAB SAMPLING
UNTIL LIKELY FRIDAY MORNING AT THE EARLIEST. EXPECT UNCERTAINTY TO
CLOUD THE FORECAST UNTIL THAT POINT WITH THE SPECIFICS OF THE TRACK
OF SFC LOW. A CONSENSUS WAS RETAINED FOR POPS NOW. FOR OVERALL PTYPE
LEANED ON LARGE SCALE THICKNESSES...THOUGH WHERE FLOW WAS ONSHORE
OFF THE GREAT LAKES...KEPT SOME MENTION OF RAIN AS WELL WITH TEMPS
EXPECTED TO BE IN THE MID 30S. LINGERED CHANCE POPS FOR MAINLY SNOW
OVER THE EAST ON SUNDAY. NOT A LOT OF COLD AIR FCST TO BE AROUND IN
WAKE OF THE MAINLY SOUTHERN STREAM ORIGIN SYSTEM...SO KEPT POPS FOR
ANY LK EFFECT INTO MONDAY ON THE LOW SIDE.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 714 AM EST TUE DEC 11 2012
EXPECT CIGS AT OR SLIGHTLY ABOVE MVFR MOST OF THE DAY WITH
INCREASING SW FLOW AHEAD OF A AN APPROACHING TROUGH. MORE
PERSISTENT MVFR CONDITIONS MIGHT IMPACT CMX/IWD IN THE AFTN AS
THIS TROF CLOSES IN...LIMITED LLVL MSTR RETURN WL LIKELY LEAD TO A
PERSISTENCE OF MAINLY VFR WX. FOLLOWING THE TROF PASSAGE AND WIND
SHIFT TO THE W IN THE EARLY EVNG...EXPECT SHSN TO IMPACT THE EXPOSED
KEWEENAW PENINSULA...WITH IFR OR LIFT CONDITIONS LIKELY AT CMX.
DOWNSLOPE NATURE OF W WIND BEHIND THIS TROF PASSAGE WL LIKELY RESULT
IN VFR CIGS AT SAW.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 545 AM EST TUE DEC 11 2012
WINDS 25 KTS OR BLO THROUGH MIDDAY WEDNESDAY THEN EXPECT INCREASING
SOUTH TO SOUTHWEST WINDS LATE WEDNESDAY/WEDNESDAY NIGHT AND INTO
EARLY THURSDAY MORNING. GALES LIKELY OVER EASTERN PORTIONS OF LAKE
SUPERIOR SO HAVE ISSUED GALE WATCH. TROUGH DROPS ACROSS THE LAKE BY
THURSDAY EVENING. WINDS WILL DIMINISH SIGNIFICANTLY THURSDAY NIGHT
INTO FRIDAY IN WAKE OF THIS TROUGH. LOW PRESSURE SYSTEM DEVELOPING
IN THE PLAINS PUSHES INTO WESTERN GREAT LAKES LATE SATURDAY INTO
SUNDAY WHILE HIGH PRESSURE MOVES ACROSS NEW ENGLAND. WINDS SHOULD
INCREASE FROM THE EAST ON SATURDAY OVER LAKE SUPERIOR. EXACT TRACK
AND DEPTH OF SFC LOW REMAINS UNCERTAIN THOUGH...SO DID NOT GO STRONG
ON WINDS AT THIS TIME. POSSIBLE THAT WINDS MAY EVENTUALLY NEED TO BE
INCREASED COMPARED TO WHAT IS IN THE CURRENT FORECAST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
MIZ014.
LAKE EFFECT SNOW ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR
MIZ007.
LAKE SUPERIOR...
GALE WATCH FROM WEDNESDAY EVENING THROUGH LATE WEDNESDAY NIGHT
FOR LSZ265>267.
LAKE MICHIGAN...
GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY MORNING FOR
LMZ248-250.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...JLB
MARINE...JLA
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
700 AM EST TUE DEC 11 2012
.AVIATION...
//DISCUSSION...
A POCKET OF DRY AIR HELPED SCOUR OUT STRATUS OVER THE TERMINAL SITES
DURING THE EARLY MORNING. THIS PROMISES VFR SCATTERED CLOUD
CONDITIONS THROUGH MID MORNING BEFORE CLOUDS MOVE BACK IN AS THE LOW
LEVEL FLOW BACKS TOWARD THE SOUTHWEST. EVEN THEN, VFR IS EXPECTED TO
PERSIST WITH SOME QUESTION WHETHER MVFR TO OUR SOUTH AND WEST WILL
BE ABLE TO SURVIVE THE TRIP THROUGH THE INCREASED SOUTHWEST FLOW.
DRY AIR OVER THE MID MISSISSIPPI VALLEY WILL THEN SCOUR ANY
REMAINING CLOUDS FROM THE AREA BY TONIGHT. THE EXCEPTION MAY BE AT
MBS WHERE SOUTHWEST FLOW WILL REMAIN COLD ENOUGH TO GENERATE
STRATOCU FROM LAKE MICHIGAN WHICH COULD SUSTAIN A MVFR/LOW VFR
CEILING THROUGH THE NIGHT. THESE CLOUDS COULD EVENTUALLY FILL IN
OVER POINTS SOUTH AS THE LOW LEVEL WINDS TURN MORE TOWARD THE WEST
BY SUNRISE WEDNESDAY.
FOR DTW... THE RETURN OF CLOUDS DURING THE MORNING WILL BE IN THE
VFR RANGE WITH CEILING ABOVE 5000 FEET INITIALLY, BUT ARE EXPECTED
TO LOWER TO VFR BELOW 5000 FEET BY LATE MORNING. CONFIDENCE IS HIGH
THAT DRY AIR OVER ILLINOIS WILL MOVE IN TONIGHT AND SCOUR ANY
REMAINING LOWER CLOUDS OUT OF THE AREA. MOSTLY CLEAR CONDITIONS WILL
THEN LAST UNTIL CLOSE TO SUNRISE WEDNESDAY WHEN PATCHES OF VFR
STRATOCU BELOW 5000 FEET WILL AGAIN BE POSSIBLE FROM LAKE MICHIGAN.
//DTW THRESHOLD THREATS...
* MODERATE CONFIDENCE IN TIMING AND COVERAGE OF CEILING BELOW 5000
TODAY AND LATE TONIGHT.
&&
.PREV DISCUSSION...ISSUED 349 AM EST TUE DEC 11 2012
SHORT TERM... TODAY AND TONIGHT
COMPLEXITIES IN THE FORECAST FOR TODAY INCLUDE EVOLUTION OF LAKE
EFFECT SNOW NEAR THE LAKE HURON SHORELINE DURING THE MORNING ALONG
WITH INLAND CLOUD COVERAGE THROUGHOUT THE DAY.
EARLY MORNING OBSERVATIONS FROM THE CANADIAN RADAR IN EXETER
INDICATE A BAND OF LAKE EFFECT SNOW PERCOLATING OVER THE SOUTH HALF
OF LAKE HURON WITHIN THE INCREASINGLY CONVERGENT LAKE INDUCED
SURFACE TROUGH. MODEL DEPICTIONS OF 850 MB TEMPERATURE SUGGEST
INSTABILITY IS ALREADY MORE THAN ADEQUATE WITH DELTA-T AVERAGING 18C
OVER THE SOUTH HALF OF THE LAKE. THE SOMEWHAT MUTED CONVECTION
DURING THE EARLY MORNING IS LIKELY A RESULT OF MID LEVEL SUBSIDENCE
INDICATED IN WATER VAPOR IMAGERY ON THE HEELS OF THE SHEAR AXIS
DEPARTING TO THE EAST. THIS IS EXPECTED TO CHANGE AS A SMALL BUT
SUFFICIENTLY STRONG SHORT WAVE SLIDES THROUGH LOWER MICHIGAN TOWARD
SUNRISE. THIS FEATURE HELPED SUPPORT A STRONG LAKE EFFECT BAND OVER
SOUTHERN LAKE MICHIGAN DURING THE NIGHT WITH CONVECTION DEEP ENOUGH
FOR SNOW SHOWERS TO REACH NORTHWEST OHIO. AS THE WAVE MOVES TOWARD
LAKE HURON DURING THE REST OF THE MORNING, IT IS EXPECTED TO BOOST
THE CIRCULATION WITHIN THE LAKE TROUGH AND HELP FLARE UP LAKE EFFECT
SNOW THERE AS WELL BEFORE QUICKLY SLIDING EASTWARD BY LATE MORNING.
AS THE WAVE APPROACHES, IT IS EXPECTED TO DRAW THE LAKE TROUGH
TOWARD THE SHORELINE OF THE THUMB FOR A FEW HOURS AROUND SUNRISE
BEFORE THE PASSAGE OF THE LARGE SCALE SURFACE RIDGE BACKS THE LOW
LEVEL FLOW TOWARD THE SOUTHWEST. MODIFIED RAP MODEL SOUNDINGS
INDICATE LAKE INDUCED CAPE APPROACHING 500 J/KG AND EQUILIBRIUM
LEVEL PUSHING 10 KFT BY 12Z, INGREDIENTS FOR HEAVY LAKE EFFECT SNOW
SHOWERS, BUT A LATE START AND SHORT DURATION WILL BE THE LIMITING
FACTORS IN SUPPORT OF A 1 TO 2 INCH FORECAST.
ELSEWHERE AROUND SE MICHIGAN, THE NORTHERLY LOW LEVEL FLOW HAS
BECOME JUST NEUTRAL ENOUGH TO ALLOW FOR SOME BREAKS IN THE STRATUS
DURING THE EARLY MORNING. EXPECT THIS WILL CONTINUE THROUGH LATE
MORNING BUT IN A RANDOM FASHION THAT WILL PROVIDE INTERVALS OF
PARTLY SUNNY CONDITIONS THROUGH CENTRAL PORTIONS OF LOWER MICHIGAN.
THE BACKING LOW LEVEL FLOW WILL THEN DIRECT CLOUDS, AND PERHAPS EVEN
A FEW SNOW SHOWERS, EASTWARD FROM LAKE MICHIGAN AS PART OF A LARGER
AREA OF STRATUS COVERING THE WESTERN GREAT LAKES. THE EXTRA CLOUD
COVER COMBINED WITH LATE DEVELOPING SOUTHWEST SURFACE WIND WILL
CONFINE MAX TEMPS TO THE LOWER AND MID 30S TODAY. THE SOUTHWEST FLOW
WILL CARRY IN DRY AIR FROM THE MID MISSISSIPPI VALLEY BY TONIGHT
WHICH WILL SCOUR OUT THE LOW CLOUDS BUT NOT RESULT IN MUCH WARMING.
THE INCREASED GRADIENT FLOW WILL BATTLE THE TENDENCY FOR SURFACE
WIND DECOUPLING AND RESULTANT RADIATIONAL COOLING FOR LOWS DROPPING
BACK INTO THE LOWER TO MID 20S.
LONG TERM...WEDNESDAY THROUGH MONDAY
VERY LITTLE TO DISCUSS IN THE WEDNESDAY TO FRIDAY TIMEFRAME. THE MAIN
TROUGH AXIS WILL BE OVER LOWER MICHIGAN AT THE START OF THE
PERIOD...WHICH WILL GIVE WAY TO A GENERAL RISING OF GEOPOTENTIAL
HEIGHTS THROUGH THE END OF THE WORK WEEK. SPLIT FLOW IS STILL
FORECASTED TO DEVELOP WITH THE POLAR JET AXIS REMAINING NORTH OF
LAKES SUPERIOR/HURON ALONG WITH THE PERSISTENCE OF A VERY NOTEWORTHY
SOUTHERN STREAM AXIS. GUIDANCE CAME IN MARKEDLY WARMER FOR WEDNESDAY
AND BOOSTED TEMPERATURES UPWARDS A COUPLE OF DEGREES. DAYTIME HIGHS
ARE EXPECTED TO REACH/CLIMB ABOVE 40 DEGREES FOR BOTH THURSDAY AND
FRIDAY.
A TON OF UNCERTAINTY EXISTS WITH REGARDS TO HOW THIS WEEKEND WILL
PLAY OUT. THE PERTINENT WEATHER ASPECTS WILL COME DOWN TO THE
DETAILS. UNFORTUNATELY...THE MODEL DATA SUGGESTS THAT IT WILL TAKE
UNTIL FRIDAY MORNING BEFORE THE MAIN TROUGH AXIS OF THE IMPORTANT
SHORTWAVE WILL COME ONSHORE OF SOUTHERN CA/BAJA OF MEXICO. THAT IS A
LONG TIME TO WAIT. LATEST TRENDING FOR THE 11.00Z SUITE WAS THAT THE
ECMWF ARRIVED IN MORE AGREEMENT WITH THE GFS SOLUTION. THE GFS HAS
BEEN ADVERTISING THE FIRST DEVELOPED SYSTEM (ARRIVING OVER THE GREAT
LAKES ON SATURDAY) WILL RUN INTO A EASTERN CANADIAN/GREENLAND
BLOCKING RIDGE. THE MODELS SUGGEST THAT WHAT BEGINS AS RATHER CRISP
BAROCLINIC DYNAMICS TURNS MUSHY IN AS LITTLE AS 12 HOURS. THE HIGHER
CONFIDENCE PORTION OF THIS FORECAST IS THE HIGH AMOUNT OF MOISTURE
IN TOW WITH THE SYSTEM. THE LIKELIHOOD OF WIDESPREAD PRECIPITATION
IS HIGH AND WENT AHEAD AND HIKED POPS INTO THE HIGH LIKELY RANGE FOR
SATURDAY AND SATURDAY NIGHT. THE ECMWF BRINGS THE MAIN UPPER LEVEL
PV ANOMALY NORTH OF THE SOO...WHICH SUGGESTS THAT PRECIPITATION TYPE
WILL BE ON THE WARM END OF THE SPECTRUM. THE GFS REMAINS A LITTLE
FARTHER SOUTH WITH THE PV ANOMALY...OVER LOWER MICHIGAN AND IS JUST
ONE OF MANY POINTS OF CONTENTION AMONGST THE SUITE.
MARINE...
WEAK HIGH PRESSURE WILL MOVE QUICKLY THROUGH LAKE HURON AND LOWER
MICHIGAN DURING THE AFTERNOON IN A FAVOR OF THE NEXT LOW PRESSURE
SYSTEM MOVING THROUGH NORTHERN ONTARIO. INCREASING SOUTHWEST WIND
WILL REACH GUSTS TO 30 KNOTS TONIGHT OVER THE OPEN WATERS OF CENTRAL
AND NORTHERN LAKE HURON. THE WIND WILL NOT BE QUITE AS STRONG OVER
SAGINAW BAY BUT STRONG ENOUGH TO BUILD WAVES OVER 4 FEET TONIGHT
THROUGH WEDNESDAY REQUIRING A SMALL CRAFT ADVISORY THERE. A LARGER
SYSTEM IS THEN EXPECTED TO TRACK THROUGH NORTHERN ONTARIO AS WELL
DURING WEDNESDAY NIGHT INTO THURSDAY THAT WILL MAINTAIN SOUTHWEST
WIND OVER THE LAKES AND BRING WARMER AIR OVER THE WATER. THE
INCREASED STABILITY BY THIS TIME WILL LIMIT GUST POTENTIAL TO 30
KNOTS OR LESS THROUGH THURSDAY BEFORE THE TRAILING COLD FRONT
SETTLES OVER THE REGION BY FRIDAY. THE FRONT WILL STALL OVER THE
CENTRAL LAKES AS A STRONG LOW PRESSURE SYSTEM TAKES SHAPE OVER THE
PLAINS STATES AND MOVES INTO THE GREAT LAKES DURING THE WEEKEND.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS
FROM PORT AUSTIN TO HARBOR BEACH...FROM 7 PM TUESDAY TO 4 PM
WEDNESDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....BT
SHORT TERM...BT
LONG TERM....CB
MARINE.......BT
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
546 AM EST TUE DEC 11 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 545 AM EST TUE DEC 11 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
FROM NRN HUDSON BAY INTO THE CNTRL CONUS. WEAK SHORTWAVE TROUGHS
FROM CNTRL UPPER MI INTO ERN WI AND OVER MN SUPPORTED AREAS OF VERY
LIGHT SNOW AND FLURRIES. ALTHOUGH RADARS SHOWED DECENT COVERAGE WITH
WEAK RETURNS...OBS INDICATED UPSTREAM VISIBILITIES WERE GENERALLY
AOA 6SM. AT THE SFC...SRLY WINDS WERE INCREASING OVER THE REGION
AHEAD OF TROUGH THAT EXTENDED FROM NW ONTARIO INTO MN.
WITH LIGHT WINDS OVER LAKE MICHIGAN AND LAND BREEZES BECOMING MORE
PROMINENT...MID LAKE LES HAD DEVELOPED OFFSHORE FROM NW LOWER MI.
MAIN FCST CONCERNS ARE LAKE EFFECT SNOW TRENDS/AMOUNTS OFF OF LAKE
MICHIGAN TODAY AND INTO THE KEWEENAW TONIGHT.
TODAY...AS THE MOISTURE AND LIGHT PCPN ASSOCIATED WITH THE SHRTWVS
ADVANCE TO THE EAST AND CONVERGENT SRLY FLOW INCREASES ACROSS LAKE
MICHIGAN...MDLS SUGGEST THAT A DOMINANT LES BAND IS LIKELY TO
DEVELOP. THE HIGH RES MODELS CONSENSUS ALSO INDICATE THAT THE BAND WOULD
LIKELY MOVE ONSHORE EAST OF ISQ AND SPREAD QUICKLY TO THE NORTH AND
EAST INTO LUCE COUNTY BY MID MORNING. ALTHOUGH CONFIDENCE IS HIGH
THAT A BAND WILL MOVE INTO EASTERN UPPER MICHIGAN...THERE IS STILL
UNCERTAINTY WITH THE DETAILS OF TIMING/LOCATION OF THE BAND. WITH A
LONG FETCH ACROSS THE LAKE...AND MODERATE INSTABILITY (850 MB TEMP
OF -11C AND LAKE SFC NEAR 6C)...MODERATE TO STRONG CONV...AND
INVERSION HEIGHTS TO AROUND 10K FT...SNOWFALL INTENSITY SHOULD
BECOME HEAVY AT TIMES. EVEN IF 1-2 INCH PER HOUR SNOWFALL RATES
DEVELOP...THE STEADY EASTWARD PROGRESSION SHOULD LIMIT LCL MAX SNOW
AMOUNTS TO AROUND 4 INCHES. SO...AN LES ADVY WAS POSTED FOR SRN
SCHOOLCRAFT AND LUCE COUNTIES.
OTHERWISE...THE BEST CHANCE FOR ADDITIONAL FLURRIES OR LIGHT SNOW
SHOWERS THIS AFTERNOON WILL BE OVER THE WRN CWA AS YET ANOTHER WEAK
SHRTWV MOVES FROM WRN MN MOVES TOWARD THE AREA.
TONIGHT...THE NW ONTARIO TROUGH WILL MOVE TO THE EAST DRAGGING A
COLD FRONT INTO WRN LAKE SUPERIOR. THE COLDER AIR ALONG WITH WINDS
VEERING WRLY WILL PROVIDE FAVORABLE CONDITIONS FOR LES INTO THE
KEWEENAW. WITH 850 MB TEMPS DROPPING TO AROUND -14C...INVERSION
HEIGHTS AROUND 7K FT...AND LOW LEVEL CONVERGENCE STRENGTHENING
DOWNWIND FROM THE APOSTLE ISLANDS...A MODERATE TO HEAVY LES BAND IS
EXPECTED TO DEVELOP. SNOWFALL AMOUNTS OF AT LEAST 2 TO 4 INCHES ARE
LIKELY...ESPECIALLY IN THE HIGHER TERRAIN FROM TWIN LAKES TO CALUMET.
SINCE THERE STILL IS UNCERTAINTY WITH THE DURATION AND LOCATION OF
THE MAIN LES BAND(S)...NO HEADLINE WAS ISSUED AT THIS TIME.
SUBSIDENCE WITH QUICKLY LOWERING INVERSION HEIGHTS AND DIMINISHING
LES INTENSITY IS EXPECTED AFTER MIDNIGHT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 545 AM EST TUE DEC 11 2012
AS STRONG H3 JET REFOCUSES OVER EASTERN SEABOARD BY THURSDAY...
EXPECT AMPLIFIED TROUGHING CURRENTLY IN PLACE OVER MUCH OF CONUS
TO TRANSITION TO SPLIT ZONAL FLOW. NORTHERN PLAINS AND UPPER GREAT
LAKES WILL BE AFFECTED BY NORTHERN STREAM THROUGH REST OF THE WORK
WEEK. DISTURBANCES IN THE NORTHERN STREAM NOT FORECAST TO BE ALL
THAT STRONG AND SINCE MAJORITY THE ENERGY FROM STRONGER SHORTWAVES
STAYS MORE OVER CANADA...EXPECT ONLY MINOR IMPACT TO SENSIBLE WX OVR
LAKE SUPERIOR AND UPR MICHIGAN.
A BIT OF LK EFFECT SNOW TO CONTEND WITH OVER THE KEWEENAW TO OPEN
THE LONG TERM PERIOD ON WEDNESDAY MORNING. KEPT 20 POPS IN THROUGH
MID MORNING...BUT THE SUBSIDENCE/DRYING AOA 850MB/LOWERING INVERSION
AND QUICKLY BACKING BLYR FLOW WILL END ANY WHATEVER LK EFFECT
LINGERS PAST 12Z IN SHORT ORDER. ATTN THEN TURNS TO LEAD WAVE
ZIPPING ALONG US/CANADIAN BORDER LATER WEDNESDAY IN INCREASINGLY
ZONAL FLOW. LARGER SCALE DYNAMICS WITH THE WAVE /H7-H5 Q-VECTOR
CONVERGENCE AND LEFT EXIT REGION JET FORCING/ STAYS MOSTLY OVER
ONTARIO WEDNESDAY AFTN AND WEDNESDAY NIGHT. ONLY MODELS THAT GRAZE
NORTHERN CWA /KEWEENAW AND LUCE COUNTY/ WITH QPF ARE THE 00Z
CANADIAN GEM-NH AND UKMET. OTHER MODELS ARE QUITE DRY BLO THE CLOUD
BASE AROUND H7...SO IT TAKES UNTIL PARCELS REACH OVER NORTHERN LK
SUPERIOR/NORTHERN ONTARIO TO SATURATE/PRECIPITATE. DID NOT WANT TO
COMPLETELY IGNORE GEM-NH AND UKMET...BUT KEPT POPS IN THE FAR NORTH
NO MORE THAN 20 PCT. BEGINNING TO THINK THAT INSTEAD OF PRECIP THAT
GUSTY SW WINDS AND STEADY TEMPS IN THE UPR 20S TO MID 30S MAY BE
MAIN PRIMARY RESULT FROM THIS INITIAL WAVE. H925-H85 WINDS 35-45 KTS
ALONG WITH NEUTRAL TO SLIGHLY UNSTABLE TEMPERATURE PROFILE SFC-H9
ALONG WITH PRESSURE FALLS OVR LK SUPERIOR AND INTO ONTARIO MAY
RESULT IN AREAS NEAR LK SUPERIOR OVR NCNTRL UPR MICHIGAN...NEAR LK
MICHIGAN AND OVER MUCH OF EASTERN CWA GUSTING SEEING WINDS GUSTING
20-35 MPH THROUGH THE NIGHT WITH MINIMAL TEMP FALL. WENT WITH
NON-DIURNAL TEMP TREND TO COVER THIS POSSIBILITY.
LEAD WAVE HEADS TOWARD QUEBEC BY DAYBREAK THURSDAY AS SFC TROUGH
EASES ACROSS LK SUPERIOR/NORTHERN UPR MICHIGAN. ANOTHER WAVE IS
LURKING UPSTREAM IN THE QUICK ZONAL FLOW ALOFT. UKMET/GEM-NH
STRONGEST WITH WAVE...GFS/ECMWF NOT SO MUCH. SINCE THE LOW-LEVEL
TROUGH BECOMES PARALLEL WITH UPPER FLOW...NOT TOO KEEN ON PUSHING
TROUGH AS FAR SOUTH AS GEM-NH HAS IT BY THURSDAY AFTN. INSTEAD KEPT
BOUNDARY HUNG UP OVR KEWEENAW WITH JUST A SMALL CHANCE OF SNOW
SHOWERS BY AFTN AS SHALLOW COLD AIR TRIES TO SETTLE BACK ACROSS
NORTHERN CWA. TEMPS AHEAD OF FRONT...WHEREVER IT ENDS UP...COULD
GET FAIRLY WARM WITH READINGS WELL INTO THE 30S...ESPECIALLY EAST.
FOR THURSDAY NIGHT INTO FRIDAY...MAY BE SETTING UP FOR ANOTHER
DZ/FZDZ OR SNOW SCENARIO. GFS IS COLDER...BUT GFS/ECMWF/GEM-NHEM
INDICATE H85 TEMPS BORDERLINE TO GET ICE NUCLEATION/SNOW. ALSO GFS
AND ECMWF INDICATE A LOT OF LOW-LEVEL MOISTURE BUT NOT AS MUCH H85
MOISTURE. INTRODUCED SOME DZ/FZDZ FOR FRIDAY AND FRIDAY NIGHT
BETWEEN THE TROUGH THAT DROPS THROUGH LATE THURSDAY AND OUT AHEAD
OF STRONGER LOW PRESSURE SYSTEM MOVING INTO REGION NEXT WEEKEND.
UPSLOPE NE THEN SE WINDS WOULD ONLY HELP OUT THE DZ/FZDZ.
AS FLOW BECOMES SPLIT LATE THIS WEEK...STRONG SOUTHERN STREAM WAVE
TAKES SHAPE OVER DESERT SOUTHWEST. IT IS THIS WAVE THAT BECOMES MAIN
INSTIGATOR FOR LEE ROCKIES CYCLOGENESIS LATE FRIDAY INTO SATURDAY.
THIS SOUTHERN STREAM WAVE/ASSOCIATED SFC LOW ARE FORECAST TO EJECT
OUT OF SOUTHERN PLAINS INTO WESTERN GREAT LAKES OR OHIO VALLEY TO
END THE WEEKEND. FLOW PATTERN BECOMES QUITE MESSY THOUGH AS ANOTHER
WAVE WILL BE QUICKLY FOLLOWING INTO SOUTHERN PLAINS AND THERE IS
EVEN A WAVE IN THE NORTHERN STREAM THAT WILL TRY TO MAKE A RUN INTO
THE NORTHERN PLAINS...THOUGH IT DOES SEEM AT LEAST AT THIS POINT...
THAT THAT WAVE MAY GET DEFLECTED OFF INTO CANADA AWAY FROM THE FRAY.
ALL THE WAVES PROBABLY WILL END UP INTERACTING WITH EACH OTHER IN
SOME FORM OR ANOTHER. NET RESULT IS A NOT SO CLEAR CUT FORECAST OF
THE SFC LOW/THERMAL PROFILE/PRECIPITATION COVERAGE AND INTENSITY
ACROSS UPPER LAKES REGION LATER SATURDAY INTO SUNDAY. ONLY REAL
MODEL TREND OF NOTE IS GFS HAS TRENDED TOWARD ECMWF IDEA OF A MORE
CLOSED OFF SOUTHERN STREAM/SFC LOW SINCE THE 18Z RUN ON MONDAY AFTN.
TROUBLE IS THAT THIS WAVE IS STILL OVER GULF OF ALASKA THIS MORNING
AND REALLY WILL NOT BE ONSHORE OVER CONUS FOR BETTER ROAB SAMPLING
UNTIL LIKELY FRIDAY MORNING AT THE EARLIEST. EXPECT UNCERTAINTY TO
CLOUD THE FORECAST UNTIL THAT POINT WITH THE SPECIFICS OF THE TRACK
OF SFC LOW. A CONSENSUS WAS RETAINED FOR POPS NOW. FOR OVERALL PTYPE
LEANED ON LARGE SCALE THICKNESSES...THOUGH WHERE FLOW WAS ONSHORE
OFF THE GREAT LAKES...KEPT SOME MENTION OF RAIN AS WELL WITH TEMPS
EXPECTED TO BE IN THE MID 30S. LINGERED CHANCE POPS FOR MAINLY SNOW
OVER THE EAST ON SUNDAY. NOT A LOT OF COLD AIR FCST TO BE AROUND IN
WAKE OF THE MAINLY SOUTHERN STREAM ORIGIN SYSTEM...SO KEPT POPS FOR
ANY LK EFFECT INTO MONDAY ON THE LOW SIDE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1222 AM EST TUE DEC 11 2012
THERE IS VERY MUCH UNCERTAINTY ON THE EVOLUTION OF THE LO CLDS OVER
UPR MI EARLY THIS MRNG. THESE CLDS HAVE PROVEN TO BE MORE TENACIOUS
THAN EARLIER EXPECTED...WITH MVFR AND EVEN SOME IFR CONDITIONS STILL
PRESENT TO THE SSW. SO TENDED TO BE MORE PESSIMISTIC WITH CIG FCSTS
DESPITE PASSAGE OF SFC HI PRES RDG/WSHFT TO THE SSW. BY LATER IN THE
MRNG...SUSPECT DRIER AIR NOW OVER MN WL MOVE INTO THE AREA WITH
INCRSG SW FLOW AHEAD OF APRCHG LO PRES TROF. ALTHOUGH SOME MVFR
CONDITIONS MIGHT IMPACT CMX/IWD IN THE AFTN AS THIS TROF CLOSES
IN...LIMITED LLVL MSTR RETURN WL LIKELY LEAD TO A PERSISTENCE OF
MAINLY VFR WX. FOLLOWING THE TROF PASSAGE/WSHFT TO THE W IN THE
EARLY EVNG...EXPECT SOME SHSN TO IMPACT THE EXPOSED KEWEENAW
PENINSULA...WITH IFR CONDITIONS LIKELY AT CMX. DOWNSLOPE NATURE OF W
WIND BEHIND THIS TROF PASSAGE WL LIKELY MAINTAIN VFR CIGS AT SAW.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 545 AM EST TUE DEC 11 2012
WINDS 25 KTS OR BLO THROUGH MIDDAY WEDNESDAY THEN EXPECT INCREASING
SOUTH TO SOUTHWEST WINDS LATE WEDNESDAY/WEDNESDAY NIGHT AND INTO
EARLY THURSDAY MORNING. GALES LIKELY OVER EASTERN PORTIONS OF LAKE
SUPERIOR SO HAVE ISSUED GALE WATCH. TROUGH DROPS ACROSS THE LAKE BY
THURSDAY EVENING. WINDS WILL DIMINISH SIGNIFICANTLY THURSDAY NIGHT
INTO FRIDAY IN WAKE OF THIS TROUGH. LOW PRESSURE SYSTEM DEVELOPING
IN THE PLAINS PUSHES INTO WESTERN GREAT LAKES LATE SATURDAY INTO
SUNDAY WHILE HIGH PRESSURE MOVES ACROSS NEW ENGLAND. WINDS SHOULD
INCREASE FROM THE EAST ON SATURDAY OVER LAKE SUPERIOR. EXACT TRACK
AND DEPTH OF SFC LOW REMAINS UNCERTAIN THOUGH...SO DID NOT GO STRONG
ON WINDS AT THIS TIME. POSSIBLE THAT WINDS MAY EVENTUALLY NEED TO BE
INCREASED COMPARED TO WHAT IS IN THE CURRENT FORECAST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
MIZ014.
LAKE EFFECT SNOW ADVISORY FROM 9 AM THIS MORNING TO 3 PM EST
THIS AFTERNOON FOR MIZ007.
LAKE SUPERIOR...
GALE WATCH FROM WEDNESDAY EVENING THROUGH LATE WEDNESDAY NIGHT
FOR LSZ265>267.
LAKE MICHIGAN...
GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY MORNING FOR
LMZ248-250.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...KC
MARINE...JLA
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
349 AM EST TUE DEC 11 2012
.SHORT TERM... TODAY AND TONIGHT
COMPLEXITIES IN THE FORECAST FOR TODAY INCLUDE EVOLUTION OF LAKE
EFFECT SNOW NEAR THE LAKE HURON SHORELINE DURING THE MORNING ALONG
WITH INLAND CLOUD COVERAGE THROUGHOUT THE DAY.
EARLY MORNING OBSERVATIONS FROM THE CANADIAN RADAR IN EXETER
INDICATE A BAND OF LAKE EFFECT SNOW PERCOLATING OVER THE SOUTH HALF
OF LAKE HURON WITHIN THE INCREASINGLY CONVERGENT LAKE INDUCED
SURFACE TROUGH. MODEL DEPICTIONS OF 850 MB TEMPERATURE SUGGEST
INSTABILITY IS ALREADY MORE THAN ADEQUATE WITH DELTA-T AVERAGING 18C
OVER THE SOUTH HALF OF THE LAKE. THE SOMEWHAT MUTED CONVECTION
DURING THE EARLY MORNING IS LIKELY A RESULT OF MID LEVEL SUBSIDENCE
INDICATED IN WATER VAPOR IMAGERY ON THE HEELS OF THE SHEAR AXIS
DEPARTING TO THE EAST. THIS IS EXPECTED TO CHANGE AS A SMALL BUT
SUFFICIENTLY STRONG SHORT WAVE SLIDES THROUGH LOWER MICHIGAN TOWARD
SUNRISE. THIS FEATURE HELPED SUPPORT A STRONG LAKE EFFECT BAND OVER
SOUTHERN LAKE MICHIGAN DURING THE NIGHT WITH CONVECTION DEEP ENOUGH
FOR SNOW SHOWERS TO REACH NORTHWEST OHIO. AS THE WAVE MOVES TOWARD
LAKE HURON DURING THE REST OF THE MORNING, IT IS EXPECTED TO BOOST
THE CIRCULATION WITHIN THE LAKE TROUGH AND HELP FLARE UP LAKE EFFECT
SNOW THERE AS WELL BEFORE QUICKLY SLIDING EASTWARD BY LATE MORNING.
AS THE WAVE APPROACHES, IT IS EXPECTED TO DRAW THE LAKE TROUGH
TOWARD THE SHORELINE OF THE THUMB FOR A FEW HOURS AROUND SUNRISE
BEFORE THE PASSAGE OF THE LARGE SCALE SURFACE RIDGE BACKS THE LOW
LEVEL FLOW TOWARD THE SOUTHWEST. MODIFIED RAP MODEL SOUNDINGS
INDICATE LAKE INDUCED CAPE APPROACHING 500 J/KG AND EQUILIBRIUM
LEVEL PUSHING 10 KFT BY 12Z, INGREDIENTS FOR HEAVY LAKE EFFECT SNOW
SHOWERS, BUT A LATE START AND SHORT DURATION WILL BE THE LIMITING
FACTORS IN SUPPORT OF A 1 TO 2 INCH FORECAST.
ELSEWHERE AROUND SE MICHIGAN, THE NORTHERLY LOW LEVEL FLOW HAS
BECOME JUST NEUTRAL ENOUGH TO ALLOW FOR SOME BREAKS IN THE STRATUS
DURING THE EARLY MORNING. EXPECT THIS WILL CONTINUE THROUGH LATE
MORNING BUT IN A RANDOM FASHION THAT WILL PROVIDE INTERVALS OF
PARTLY SUNNY CONDITIONS THROUGH CENTRAL PORTIONS OF LOWER MICHIGAN.
THE BACKING LOW LEVEL FLOW WILL THEN DIRECT CLOUDS, AND PERHAPS EVEN
A FEW SNOW SHOWERS, EASTWARD FROM LAKE MICHIGAN AS PART OF A LARGER
AREA OF STRATUS COVERING THE WESTERN GREAT LAKES. THE EXTRA CLOUD
COVER COMBINED WITH LATE DEVELOPING SOUTHWEST SURFACE WIND WILL
CONFINE MAX TEMPS TO THE LOWER AND MID 30S TODAY. THE SOUTHWEST FLOW
WILL CARRY IN DRY AIR FROM THE MID MISSISSIPPI VALLEY BY TONIGHT
WHICH WILL SCOUR OUT THE LOW CLOUDS BUT NOT RESULT IN MUCH WARMING.
THE INCREASED GRADIENT FLOW WILL BATTLE THE TENDENCY FOR SURFACE
WIND DECOUPLING AND RESULTANT RADIATIONAL COOLING FOR LOWS DROPPING
BACK INTO THE LOWER TO MID 20S.
&&
.LONG TERM...WEDNESDAY THROUGH MONDAY
VERY LITTLE TO DISCUSS IN THE WEDNESDAY TO FRIDAY TIMEFRAME. THE MAIN
TROUGH AXIS WILL BE OVER LOWER MICHIGAN AT THE START OF THE
PERIOD...WHICH WILL GIVE WAY TO A GENERAL RISING OF GEOPOTENTIAL
HEIGHTS THROUGH THE END OF THE WORK WEEK. SPLIT FLOW IS STILL
FORECASTED TO DEVELOP WITH THE POLAR JET AXIS REMAINING NORTH OF
LAKES SUPERIOR/HURON ALONG WITH THE PERSISTENCE OF A VERY NOTEWORTHY
SOUTHERN STREAM AXIS. GUIDANCE CAME IN MARKEDLY WARMER FOR WEDNESDAY
AND BOOSTED TEMPERATURES UPWARDS A COUPLE OF DEGREES. DAYTIME HIGHS
ARE EXPECTED TO REACH/CLIMB ABOVE 40 DEGREES FOR BOTH THURSDAY AND
FRIDAY.
A TON OF UNCERTAINTY EXISTS WITH REGARDS TO HOW THIS WEEKEND WILL
PLAY OUT. THE PERTINENT WEATHER ASPECTS WILL COME DOWN TO THE
DETAILS. UNFORTUNATELY...THE MODEL DATA SUGGESTS THAT IT WILL TAKE
UNTIL FRIDAY MORNING BEFORE THE MAIN TROUGH AXIS OF THE IMPORTANT
SHORTWAVE WILL COME ONSHORE OF SOUTHERN CA/BAJA OF MEXICO. THAT IS A
LONG TIME TO WAIT. LATEST TRENDING FOR THE 11.00Z SUITE WAS THAT THE
ECMWF ARRIVED IN MORE AGREEMENT WITH THE GFS SOLUTION. THE GFS HAS
BEEN ADVERTISING THE FIRST DEVELOPED SYSTEM (ARRIVING OVER THE GREAT
LAKES ON SATURDAY) WILL RUN INTO A EASTERN CANADIAN/GREENLAND
BLOCKING RIDGE. THE MODELS SUGGEST THAT WHAT BEGINS AS RATHER CRISP
BAROCLINIC DYNAMICS TURNS MUSHY IN AS LITTLE AS 12 HOURS. THE HIGHER
CONFIDENCE PORTION OF THIS FORECAST IS THE HIGH AMOUNT OF MOISTURE
IN TOW WITH THE SYSTEM. THE LIKELIHOOD OF WIDESPREAD PRECIPITATION
IS HIGH AND WENT AHEAD AND HIKED POPS INTO THE HIGH LIKELY RANGE FOR
SATURDAY AND SATURDAY NIGHT. THE ECMWF BRINGS THE MAIN UPPER LEVEL
PV ANOMALY NORTH OF THE SOO...WHICH SUGGESTS THAT PRECIPITATION TYPE
WILL BE ON THE WARM END OF THE SPECTRUM. THE GFS REMAINS A LITTLE
FARTHER SOUTH WITH THE PV ANOMALY...OVER LOWER MICHIGAN AND IS JUST
ONE OF MANY POINTS OF CONTENTION AMONGST THE SUITE.
&&
.MARINE...
WEAK HIGH PRESSURE WILL MOVE QUICKLY THROUGH LAKE HURON AND LOWER
MICHIGAN DURING THE AFTERNOON IN A FAVOR OF THE NEXT LOW PRESSURE
SYSTEM MOVING THROUGH NORTHERN ONTARIO. INCREASING SOUTHWEST WIND
WILL REACH GUSTS TO 30 KNOTS TONIGHT OVER THE OPEN WATERS OF CENTRAL
AND NORTHERN LAKE HURON. THE WIND WILL NOT BE QUITE AS STRONG OVER
SAGINAW BAY BUT STRONG ENOUGH TO BUILD WAVES OVER 4 FEET TONIGHT
THROUGH WEDNESDAY REQUIRING A SMALL CRAFT ADVISORY THERE. A LARGER
SYSTEM IS THEN EXPECTED TO TRACK THROUGH NORTHERN ONTARIO AS WELL
DURING WEDNESDAY NIGHT INTO THURSDAY THAT WILL MAINTAIN SOUTHWEST
WIND OVER THE LAKES AND BRING WARMER AIR OVER THE WATER. THE
INCREASED STABILITY BY THIS TIME WILL LIMIT GUST POTENTIAL TO 30
KNOTS OR LESS THROUGH THURSDAY BEFORE THE TRAILING COLD FRONT
SETTLES OVER THE REGION BY FRIDAY. THE FRONT WILL STALL OVER THE
CENTRAL LAKES AS A STRONG LOW PRESSURE SYSTEM TAKES SHAPE OVER THE
PLAINS STATES AND MOVES INTO THE GREAT LAKES DURING THE WEEKEND.
&&
.AVIATION...ISSUED 1207 AM EST TUE DEC 11 2012
//DISCUSSION...
MVFR STRATUS WILL REMAIN IN PLACE OVER THE AREA WITHIN CYCLONICALLY
CURVED NORTHWEST FLOW THROUGH THE CENTRAL GREAT LAKES. THIS REGIME
WILL COME TO AN END MID/LATE MORNING AS SOUTHWEST WINDS DEVELOP
BETWEEN HIGH PRESSURE DEPARTING INTO QUEBEC AND LOW PRESSURE
TRACKING ALONG THE FAR NORTHERN GREAT LAKES/SOUTHERN ONTARIO.
DURING THE 14Z-16Z TIME FRAME...EXPECT STRATUS TO BEGIN BREAKING
UP WITH VFR CONDITIONS EXPECTED IN THE AFTERNOON/TUESDAY EVENING.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILINGS BELOW 5000 FEET PERSISTING THROUGH
14Z-16Z.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS
FROM PORT AUSTIN TO HARBOR BEACH...FROM 7 PM TUESDAY TO 4 PM
WEDNESDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...BT
LONG TERM....CB
MARINE.......BT
AVIATION.....DG
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
941 PM CST WED DEC 12 2012
.UPDATE...FCST ON TRACK. MAIN FEATURE IS AREA OF LOW/MID LVL
FRONTOGENESIS OVER NORTH DAKOTA MOVING EAST. SHORT RANGE HI-RES MODELS
DIFFER SOMEWHAT ON FUTURE MOVEMENT OF THIS AXIS OF FORCING. HRRR
TAKES AXIS FROM CASS LAKE TO TWO HARBORS WHILE NAM12 TRACKS THE
AXIS FROM BRAINERD TO ASHLAND. SHOULD SEE UP TO AN INCH
ACCUMULATION WITHIN THE AXIS.
&&
.PREV DISCUSSION... /ISSUED 538 PM CST WED DEC 12 2012/
AVIATION...00Z TAF ISSUANCE...
MAINTAINED STRONG CONTINUITY WITH PREVIOUS FCSTS WHICH KEEPS MOST
LIKELY AREA OF MVFR CEILINGS NEAR KINL THIS EVENING. THIS IS
ASSOCIATED WITH INVERTED SFC TROUGH/85H LOW TRACKING NORTH OF
BORDER OVERNIGHT. POTENTIAL LOWERING OF CEILING TO MVFR AT
KHIB/KBRD/KDLH BY EARLY MORNING WITH AREA OF SNOW PRODUCED BY MID
LVL FORCING.
PREV DISCUSSION... /ISSUED 310 PM CST WED DEC 12 2012/
SHORT TERM.../NOW - THURSDAY NIGHT/
THE FOCUSES FOR THIS FORECAST INCLUDE CHANCES OF LIGHT SNOW
THROUGH THIS EVENING...AND AGAIN FOR LATE TONIGHT INTO THURSDAY
AFTERNOON...BOTH OF WHICH MAINLY AFFECT THE NORTHERN TIER OF NE
MINNESOTA COUNTIES.
LIGHT SNOW WILL CONTINUE TO BE POSSIBLE ACROSS PARTS OF THE FAR
NORTHERN FA...MAINLY FAR NE MINNESOTA...THROUGH THIS EVENING DUE
TO THE WARM SOUTHERLY FLOW OVER A PASSING INVERTED TROUGH.
HOWEVER...MOST OF THE SNOW WILL FALL IN ONTARIO. ADDED PATCHY FOG
TO THE FAR NORTH SHORE OF THE ARROWHEAD THROUGH EARLY THIS EVENING
DUE TO THE ONSHORE WINDS WITH LONG FETCH...BUT THE FOG SHOULD
BEGIN TO DISSIPATE LATER THIS EVENING WHEN THE WIND DIRECTION
CHANGES. AS THE INVERTED TROUGH MOVES THROUGH THE FA TONIGHT...THE
SOUTHERLY WINDS WILL SUBSIDE AND BEGIN TO BECOME NORTHERLY. CLOUD
COVER WILL HELP PROP UP OVERNIGHT TEMPERATURES WITH LOWS MAINLY IN
THE TEENS AND TWENTIES...EXCEPT FOR SINGLE DIGITS IN THE FAR NW
FA.
THE MODELS ARE IN FAIRLY GOOD AGREEMENT ABOUT A FRONTOGENETICAL
BAND OF LIGHT SNOW MOVING IN FROM NW MINNESOTA INTO NE MINNESOTA
LATE TONIGHT AND TOMORROW MORNING. THIS BAND OF LIGHT SNOW NORTH
OF THE STATIONARY FRONT COULD LINGER INTO THURSDAY AFTERNOON. MOST
AFFECTED AREAS ACROSS NE MINNESOTA WILL PROBABLY GET AT LEAST A
COUPLE TENTHS OF AN INCH...BUT WOULD NOT BE SURPRISED BY IF SOME
AREAS GET AROUND AN INCH. EXPECT A CLOUDY DAY...EXCEPT IN PARTS OF
THE FAR SE FA WHERE THERE SHOULD BE SOME PEAKS OF SUNSHINE. HIGH
TEMPERATURES SHOULD RANGE FROM THE LOW 30S ACROSS THE SE FA TO THE
TEENS IN THE NW FA.
HIGH PRESSURE WILL MOVE INTO THE NORTHLAND THURSDAY NIGHT...SO
BESIDES SOME POSSIBLE LINGERING LIGHT SNOW OVER THE
ARROWHEAD...THE REST OF THE FA SHOULD BE DRY. THE PARTLY TO MOSTLY
CLOUDY SKIES WILL HELP PROP UP TEMPERATURES. OVERNIGHT LOWS WILL
RANGE FROM THE UPPER TEENS IN THE SE FA TO THE LOWER SINGLE DIGITS
IN THE NW FA.
LONG TERM.../FRIDAY - WEDNESDAY/
FOCUS DURING THIS PERIOD WILL BE ON A SYSTEM BRINGING
PRECIPITATION TO THE NORTHLAND THIS WEEKEND...POSSIBLY A MIX
FRIDAY NIGHT INTO SATURDAY MORNING. THE MODELS ARE IN PRETTY GOOD
AGREEMENT WITH THE SYSTEM THIS WEEKEND...AND A BLEND OF THE GFS
AND ECMWF WAS USED FOR MOST OF THE FORECAST DETAILS. THE NAM IS
FURTHER NORTH WITH THE TRACK...AND IS WARMER IN THE LOW LEVELS AS
A RESULT.
THE UPPER LEVEL SYSTEM OF CONCERN THIS WEEKEND WILL START OVER THE
CA/AZ/MEXICO AREA FRIDAY MORNING...THEN MOVE NORTHEAST TOWARD
THE NORTHLAND. FRIDAY WILL BE DRY OVER THE REGION. WARM AIR
ADVECTION AND THE APPROACHING UPPER TROUGH MAY BE ENOUGH TO CAUSE
SOME LIGHT PRECIPITATION LATE FRIDAY NIGHT...MAINLY OVER THE
SOUTHERN HALF OF THE CWA. PRECIPITATION TYPE IS IN QUESTION...AS
THE MODELS DO SHOW A WARM NOSE WHICH COULD CAUSE A WINTRY MIX OF
SNOW/FREEZING RAIN OR SLEET FRIDAY NIGHT/SATURDAY MORNING OVER
SOUTHERN AREAS. SEVERAL OF THE MODELS HAVE TRENDED A BIT FURTHER
NORTH WITH THIS SYSTEM WHICH DOES TWO THINGS 1) BRINGS A BETTER
CHANCE FOR PRECIPITATION INTO THE NORTHLAND AND 2) BRINGS IN
WARMER LOW LEVEL TEMPERATURES COMPLICATING THE PRECIPITATION TYPE
FORECAST. AS THE UPPER TROUGH AND SURFACE LOW MOVE OVER WISCONSIN
SATURDAY...PRECIPITATION SHOULD BECOME MORE WIDESPREAD AND BOTH
THE GFS AND ECMWF SUGGEST MAINLY SNOW WILL FALL DURING THE DAY
SATURDAY. AT THIS POINT...IT APPEARS SEVERAL INCHES OF SNOW WILL
BE POSSIBLE BY LATE SATURDAY EVENING...WITH THE BEST CHANCE
OCCURRING OVER NORTHWEST WISCONSIN. THE STRONGEST FORCING LOOKS TO
REMAIN SOUTH OF THE NORTHLAND...AND AT THIS POINT THERE DOES NOT
LOOK TO BE A SIGNIFICANT CONTRIBUTION OF LIFT FROM FGEN. WARMER
TEMPERATURES AT 850MB ALSO MEANS ANY LAKE CONTRIBUTION WILL BE
QUITE LIMITED. IT`S JUST TOO EARLY TO FORECAST SPECIFIC SNOW
AMOUNTS...AND DETAILS WILL BE ADDED LATER. THOSE WITH TRAVEL PLANS
OVER THE WEEKEND SHOULD MONITOR LATER FORECASTS AND STATEMENTS. WE
EXPECT HIGHS SATURDAY NEAR 30 OVER THE FAR NORTH...AND THE LOWER
THIRTIES OVER NORTHWEST WISCONSIN.
THE REST OF THE EXTENDED PERIOD LOOKS RELATIVELY QUIET AND WE HAVE
PERIODIC CHANCES FOR LIGHT SNOW. TEMPERATURES SHOULD BE SEVERAL
DEGREES ABOVE NORMAL THIS WEEKEND...THEN COOL TO NORMAL BY TUESDAY
INTO WEDNESDAY.
AVIATION.../18Z TAF ISSUANCE/
MAINLY VFR CONDITIONS COVERED THE NORTHLAND AS OF LATE
MORNING...WITH SOME LOWER CEILINGS AND SOME LIGHT SNOW ALONG THE
NORTH SHORE DUE TO ONSHORE WINDS THERE. WAA CONTINUED OVER THE
NORTHLAND...AND STILL MAY LEAD TO SOME LIGHT SNOW AND LOWERING
CEILINGS OVER THE FAR NORTH THIS AFTERNOON. WE DID DELAY THE LOWER
CEILINGS...AND REMOVED THE MENTION FROM KDLH. KDLH WAS
EXPERIENCING A SCATTERED DECK AS LOW AS 400FT THIS MORNING...BUT
AS TEMPS WARM THIS AFTERNOON...LAKE GENERATED CLOUDS SHOULD BECOME
MORE SCARCE. THE RAP AND NAM BOTH SUGGEST LOWER CEILINGS WILL
DEVELOP OVER THE NORTH...MAINLY AFFECTING KINL.
TONIGHT...WE COULD SEE SOME FOG IN SPOTS. A WEAK WAVE WILL MOVE
THROUGH THE AREA AS WELL...AND WITH THIS THERMAL GRADIENT IN
PLACE...SOME LIGHT SNOW WILL BE POSSIBLE. WE ADDED THE MENTION TO
ALL TAFS EXCEPT KHYR. SOME LOWER CEILINGS...WILL ALSO BECOME MORE
LIKELY AS THE NIGHT PROGRESSES. WINDS WILL TURN TO THE NORTH TO
NORTHEAST LATE TONIGHT INTO THURSDAY MORNING.
&&
.POINT TEMPS/POPS...
DLH 22 30 15 28 / 20 20 10 10
INL 7 17 4 21 / 10 10 10 10
BRD 19 27 11 28 / 20 10 10 10
HYR 24 34 16 32 / 10 0 0 10
ASX 25 33 21 32 / 10 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 4 AM CST THURSDAY FOR LSZ140-141.
&&
$$
SHORT TERM...CANNON
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
538 PM CST WED DEC 12 2012
.AVIATION...00Z TAF ISSUANCE...
MAINTAINED STRONG CONTINUITY WITH PREVIOUS FCSTS WHICH KEEPS MOST
LIKELY AREA OF MVFR CEILINGS NEAR KINL THIS EVENING. THIS IS
ASSOCIATED WITH INVERTED SFC TROUGH/85H LOW TRACKING NORTH OF
BORDER OVERNIGHT. POTENTIAL LOWERING OF CEILING TO MVFR AT
KHIB/KBRD/KDLH BY EARLY MORNING WITH AREA OF SNOW PRODUCED BY MID
LVL FORCING.
&&
.PREV DISCUSSION... /ISSUED 310 PM CST WED DEC 12 2012/
SHORT TERM.../NOW - THURSDAY NIGHT/
THE FOCUSES FOR THIS FORECAST INCLUDE CHANCES OF LIGHT SNOW
THROUGH THIS EVENING...AND AGAIN FOR LATE TONIGHT INTO THURSDAY
AFTERNOON...BOTH OF WHICH MAINLY AFFECT THE NORTHERN TIER OF NE
MINNESOTA COUNTIES.
LIGHT SNOW WILL CONTINUE TO BE POSSIBLE ACROSS PARTS OF THE FAR
NORTHERN FA...MAINLY FAR NE MINNESOTA...THROUGH THIS EVENING DUE
TO THE WARM SOUTHERLY FLOW OVER A PASSING INVERTED TROUGH.
HOWEVER...MOST OF THE SNOW WILL FALL IN ONTARIO. ADDED PATCHY FOG
TO THE FAR NORTH SHORE OF THE ARROWHEAD THROUGH EARLY THIS EVENING
DUE TO THE ONSHORE WINDS WITH LONG FETCH...BUT THE FOG SHOULD
BEGIN TO DISSIPATE LATER THIS EVENING WHEN THE WIND DIRECTION
CHANGES. AS THE INVERTED TROUGH MOVES THROUGH THE FA TONIGHT...THE
SOUTHERLY WINDS WILL SUBSIDE AND BEGIN TO BECOME NORTHERLY. CLOUD
COVER WILL HELP PROP UP OVERNIGHT TEMPERATURES WITH LOWS MAINLY IN
THE TEENS AND TWENTIES...EXCEPT FOR SINGLE DIGITS IN THE FAR NW
FA.
THE MODELS ARE IN FAIRLY GOOD AGREEMENT ABOUT A FRONTOGENETICAL
BAND OF LIGHT SNOW MOVING IN FROM NW MINNESOTA INTO NE MINNESOTA
LATE TONIGHT AND TOMORROW MORNING. THIS BAND OF LIGHT SNOW NORTH
OF THE STATIONARY FRONT COULD LINGER INTO THURSDAY AFTERNOON. MOST
AFFECTED AREAS ACROSS NE MINNESOTA WILL PROBABLY GET AT LEAST A
COUPLE TENTHS OF AN INCH...BUT WOULD NOT BE SURPRISED BY IF SOME
AREAS GET AROUND AN INCH. EXPECT A CLOUDY DAY...EXCEPT IN PARTS OF
THE FAR SE FA WHERE THERE SHOULD BE SOME PEAKS OF SUNSHINE. HIGH
TEMPERATURES SHOULD RANGE FROM THE LOW 30S ACROSS THE SE FA TO THE
TEENS IN THE NW FA.
HIGH PRESSURE WILL MOVE INTO THE NORTHLAND THURSDAY NIGHT...SO
BESIDES SOME POSSIBLE LINGERING LIGHT SNOW OVER THE
ARROWHEAD...THE REST OF THE FA SHOULD BE DRY. THE PARTLY TO MOSTLY
CLOUDY SKIES WILL HELP PROP UP TEMPERATURES. OVERNIGHT LOWS WILL
RANGE FROM THE UPPER TEENS IN THE SE FA TO THE LOWER SINGLE DIGITS
IN THE NW FA.
LONG TERM.../FRIDAY - WEDNESDAY/
FOCUS DURING THIS PERIOD WILL BE ON A SYSTEM BRINGING
PRECIPITATION TO THE NORTHLAND THIS WEEKEND...POSSIBLY A MIX
FRIDAY NIGHT INTO SATURDAY MORNING. THE MODELS ARE IN PRETTY GOOD
AGREEMENT WITH THE SYSTEM THIS WEEKEND...AND A BLEND OF THE GFS
AND ECMWF WAS USED FOR MOST OF THE FORECAST DETAILS. THE NAM IS
FURTHER NORTH WITH THE TRACK...AND IS WARMER IN THE LOW LEVELS AS
A RESULT.
THE UPPER LEVEL SYSTEM OF CONCERN THIS WEEKEND WILL START OVER THE
CA/AZ/MEXICO AREA FRIDAY MORNING...THEN MOVE NORTHEAST TOWARD
THE NORTHLAND. FRIDAY WILL BE DRY OVER THE REGION. WARM AIR
ADVECTION AND THE APPROACHING UPPER TROUGH MAY BE ENOUGH TO CAUSE
SOME LIGHT PRECIPITATION LATE FRIDAY NIGHT...MAINLY OVER THE
SOUTHERN HALF OF THE CWA. PRECIPITATION TYPE IS IN QUESTION...AS
THE MODELS DO SHOW A WARM NOSE WHICH COULD CAUSE A WINTRY MIX OF
SNOW/FREEZING RAIN OR SLEET FRIDAY NIGHT/SATURDAY MORNING OVER
SOUTHERN AREAS. SEVERAL OF THE MODELS HAVE TRENDED A BIT FURTHER
NORTH WITH THIS SYSTEM WHICH DOES TWO THINGS 1) BRINGS A BETTER
CHANCE FOR PRECIPITATION INTO THE NORTHLAND AND 2) BRINGS IN
WARMER LOW LEVEL TEMPERATURES COMPLICATING THE PRECIPITATION TYPE
FORECAST. AS THE UPPER TROUGH AND SURFACE LOW MOVE OVER WISCONSIN
SATURDAY...PRECIPITATION SHOULD BECOME MORE WIDESPREAD AND BOTH
THE GFS AND ECMWF SUGGEST MAINLY SNOW WILL FALL DURING THE DAY
SATURDAY. AT THIS POINT...IT APPEARS SEVERAL INCHES OF SNOW WILL
BE POSSIBLE BY LATE SATURDAY EVENING...WITH THE BEST CHANCE
OCCURRING OVER NORTHWEST WISCONSIN. THE STRONGEST FORCING LOOKS TO
REMAIN SOUTH OF THE NORTHLAND...AND AT THIS POINT THERE DOES NOT
LOOK TO BE A SIGNIFICANT CONTRIBUTION OF LIFT FROM FGEN. WARMER
TEMPERATURES AT 850MB ALSO MEANS ANY LAKE CONTRIBUTION WILL BE
QUITE LIMITED. IT`S JUST TOO EARLY TO FORECAST SPECIFIC SNOW
AMOUNTS...AND DETAILS WILL BE ADDED LATER. THOSE WITH TRAVEL PLANS
OVER THE WEEKEND SHOULD MONITOR LATER FORECASTS AND STATEMENTS. WE
EXPECT HIGHS SATURDAY NEAR 30 OVER THE FAR NORTH...AND THE LOWER
THIRTIES OVER NORTHWEST WISCONSIN.
THE REST OF THE EXTENDED PERIOD LOOKS RELATIVELY QUIET AND WE HAVE
PERIODIC CHANCES FOR LIGHT SNOW. TEMPERATURES SHOULD BE SEVERAL
DEGREES ABOVE NORMAL THIS WEEKEND...THEN COOL TO NORMAL BY TUESDAY
INTO WEDNESDAY.
AVIATION.../18Z TAF ISSUANCE/
MAINLY VFR CONDITIONS COVERED THE NORTHLAND AS OF LATE
MORNING...WITH SOME LOWER CEILINGS AND SOME LIGHT SNOW ALONG THE
NORTH SHORE DUE TO ONSHORE WINDS THERE. WAA CONTINUED OVER THE
NORTHLAND...AND STILL MAY LEAD TO SOME LIGHT SNOW AND LOWERING
CEILINGS OVER THE FAR NORTH THIS AFTERNOON. WE DID DELAY THE LOWER
CEILINGS...AND REMOVED THE MENTION FROM KDLH. KDLH WAS
EXPERIENCING A SCATTERED DECK AS LOW AS 400FT THIS MORNING...BUT
AS TEMPS WARM THIS AFTERNOON...LAKE GENERATED CLOUDS SHOULD BECOME
MORE SCARCE. THE RAP AND NAM BOTH SUGGEST LOWER CEILINGS WILL
DEVELOP OVER THE NORTH...MAINLY AFFECTING KINL.
TONIGHT...WE COULD SEE SOME FOG IN SPOTS. A WEAK WAVE WILL MOVE
THROUGH THE AREA AS WELL...AND WITH THIS THERMAL GRADIENT IN
PLACE...SOME LIGHT SNOW WILL BE POSSIBLE. WE ADDED THE MENTION TO
ALL TAFS EXCEPT KHYR. SOME LOWER CEILINGS...WILL ALSO BECOME MORE
LIKELY AS THE NIGHT PROGRESSES. WINDS WILL TURN TO THE NORTH TO
NORTHEAST LATE TONIGHT INTO THURSDAY MORNING.
&&
.POINT TEMPS/POPS...
DLH 20 30 15 28 / 20 20 10 10
INL 7 17 4 21 / 10 10 10 10
BRD 18 27 11 28 / 20 10 10 10
HYR 22 34 16 32 / 0 0 0 10
ASX 25 34 21 32 / 0 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 4 AM CST THURSDAY FOR LSZ140-141.
&&
$$
AVIATION...CANNON
AREA FORECAST DISCUSSION...CORRECTED
NWS DULUTH MN
314 PM CST TUE DEC 11 2012
.SHORT TERM...THROUGH WEDNESDAY NIGHT.
LAKE EFFECT SNOW ALONG THE NORTH SHORE HAS DIMINISHED THIS
AFTERNOON AS WINDS HAVE TURNED MORE WESTERLY BEHIND THE DEPARTING
LOW. A LAKE BAND OF LIGHT SNOW SHOWERS ALSO EXTENDED FROM JUST OFF
SHORE OF DOUGLAS COUNTY...ALONG THE BAYFIELD PENINSULA TOWARD RED
CLIFF. THIS WILL LIKELY CONTINUE THROUGH MOST OF THE EVENING AS
THE LOW LEVEL FLOW REMAINS WEST-SOUTHWEST. FETCH WILL BE
LIMITED...AND THE NAM AND RUC BOTH SHOW LOWERING RH THROUGH THE
EVENING...SO WE THINK ACCUMULATIONS WILL BE LIMITED. PLENTY OF CLOUDS
REMAIN OVER THE REST OF THE NORTHLAND...WITH FLURRIES/LIGHT SNOW
STILL OCCURRING. A WEAK SHORTWAVE WAS MOVING THROUGH CENTRAL
MINNESOTA THIS AFTERNOON...WITH RADAR HIGHER RETURNS WELL SOUTH OF
THE CWA.
HIGH PRESSURE WILL MOVE QUICKLY THROUGH THE NORTHLAND
TONIGHT...WITH WAA INCREASING OVERNIGHT AHEAD OF AN AREA OF LOW
PRESSURE. WE HAVE A CHANCE FOR LIGHT SNOW LATER TONIGHT OVER
NORTHWEST AREAS...AND INCREASED POPS TO LIKELY BETWEEN 09-12Z OVER
KOOCHICHING COUNTY. THE WAA AND WEAK SHORT WAVE WILL CONTINUE TO
IMPACT FAR NORTHERN AREAS WEDNESDAY...AND WE HAVE INCREASED POPS
TO LIKELY AS ACCUMULATIONS UP TO TWO INCHES WILL BE POSSIBLE IN
SPOTS. THERE MAY ALSO BE A NARROW WINDOW FOR LAKE EFFECT SNOW
WEDNESDAY MORNING BETWEEN LITTLE MARAIS AND GRAND PORTAGE AGAIN.
FETCH BECOMES FAVORABLE WEDNESDAY MORNING...BUT WAA WILL CAUSE
850MB TEMPS TO RISE QUICKLY. WE`LL HAVE TO KEEP A CLOSE EYE ON
THAT AREA AS WE COULD GET A QUICK BURST OF SEVERAL INCHES OF SNOW
IF THE TEMPS ALOFT DON`T WARM AS FAST AS ANTICIPATED.
TEMPERATURES TONIGHT WILL BE A CHALLENGE...AS THEY WILL BE HIGHLY
DEPENDENT ON CLEARING. WE DID DROP THEM MOST AREAS...HAVE SOME
WELL BELOW ZERO OVER NORTHEAST MINNESOTA. EVENING SHIFT WILL HAVE
TO MONITOR CLOUD TRENDS CLOSELY...AS WE MAY NOT BE COLD ENOUGH IF
IT CLEARS LONGER THAN ANTICIPATED. HIGHS WEDNESDAY WILL BE WARMER
THAN TODAY...WITH SOME AREAS REACHING AROUND THIRTY OVER NORTHWEST
WISCONSIN.
CONFIDENCE WEDNESDAY NIGHT IS LOWER THAN AVERAGE REGARDING SNOW
POTENTIAL. NAM WAS SHOWING A WEAK CIRCULATION AT 850MB AND
FORECASTS SOME LIGHT SNOW OVER THE FAR NORTH. THE MODELS ARE NOT
IN VERY GOOD AGREEMENT DURING THIS PERIOD. WE KEPT A MENTION OF
LIGHT SNOW OVER THE NORTH...AND EXPANDED A BIT SOUTH OVER OUR
WESTERN COUNTIES. IF THE MODELS TREND TOWARD THE NAM...WE WILL
NEED HIGHER POPS FOR SOME LIGHT SNOW ACCUMULATIONS OVER THE WEST
AND NORTHERN CWA.
.LONG TERM...THURSDAY - MONDAY.
THE NORTHLAND SHOULD FIND ITSELF THURSDAY MORNING WITH A STATIONARY
FRONT NEAR OR SOUTH OF THE FA. THERE MAY BE SOME LIGHT SNOW ACROSS
THE NORTHERN FA THURSDAY ASSOCIATED WITH PLENTIFUL LOW CLOUDS NORTH
OF THE FRONT. HIGH PRESSURE IN CANADA WILL BEGIN TO EXERT GREATER
INFLUENCE ON THE NORTHLAND THURSDAY NIGHT...PROVIDING DRY WEATHER
THROUGH FRIDAY NIGHT. THE MODELS ARE LATCHING ONTO A STRONG LOW
PRESSURE SYSTEM MOVING FROM THE CENTRAL PLAINS TO UPPER MIDWEST ON
SATURDAY. THIS SYSTEM COULD BRING SIGNIFICANT SNOWFALL TO PARTS OF
THE FA...ESPECIALLY THE SOUTHEASTERN FA WHICH WILL BE IN BETTER
PROXIMITY TO THE SYSTEM. TEMPERATURES THROUGH THE PERIOD SHOULD BE
NEAR OR SLIGHTLY ABOVE NORMAL.
&&
.AVIATION...18Z TAFS
IFR/MVFR CONDITIONS ACROSS NE MINNESOTA AND NW MINNESOTA ARE
EXPECTED TO CONTINUE THROUGH THIS AFTERNOON AND INTO EARLY THIS
EVENING. CIGS WILL LIKELY RANGE FROM 1500 TO 3000 FT...AND THE
-SN WILL OCCASIONALLY REDUCE VIS TO IFR. THE SNOW SHOULD BEGIN TO
SUBSIDE LATER THIS AFTERNOON. THE CLOUDS WILL BEGIN TO CLEAR AT
KINL BY MID AFTERNOON...AND THEN AT OTHER TERMINALS LATE THIS
AFTERNOON AND EARLY THIS EVENING. EXPECT THE 5 TO 10 KNOT W TO SW
WINDS TO BECOME S TO SE TONIGHT. KINL COULD SEE MVFR CIGS
REDEVELOP LATE TONIGHT AND TOMORROW MORNING...BUT VFR CONDITIONS
ARE LIKELY TO RETURN TO KDLH/KHIB/KBRD/KHYR TONIGHT.
&&
.POINT TEMPS/POPS...
DLH 3 28 20 29 / 10 10 10 20
INL -9 23 8 19 / 60 70 30 20
BRD -5 29 17 28 / 10 10 20 10
HYR 2 32 22 33 / 20 10 10 0
ASX 5 33 25 35 / 20 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 10 PM CST THIS EVENING FOR LSZ140.
&&
$$
SHORT TERM...MELDE
LONG TERM....GROCHOCINSKI
AVIATION...GROCHOCINSKI
AREA FORECAST DISCUSSION
NWS DULUTH MN
306 PM CST TUE DEC 11 2012
.SHORT TERM...THROUGH WEDNESDAY NIGHT.
LAKE EFFECT SNOW ALONG THE NORTH SHORE HAS DIMINISHED THIS
AFTERNOON AS WINDS HAVE TURNED MORE WESTERLY BEHIND THE DEPARTING
LOW. A LAKE BAND OF LIGHT SNOW SHOWERS ALSO EXTENDED FROM JUST OFF
SHORE OF DOUGLAS COUNTY...ALONG THE BAYFIELD PENINSULA TOWARD RED
CLIFF. THIS WILL LIKELY CONTINUE THROUGH MOST OF THE EVENING AS
THE LOW LEVEL FLOW REMAINS WEST-SOUTHWEST. FETCH WILL BE
LIMITED...AND THE NAM AND RUC BOTH SHOW LOWERING RH THROUGH THE
EVENING...SO WE THINK ACCUMULATIONS WILL BE LIMITED. PLENTY OF CLOUDS
REMAIN OVER THE REST OF THE NORTHLAND...WITH FLURRIES/LIGHT SNOW
STILL OCCURRING. A WEAK SHORTWAVE WAS MOVING THROUGH CENTRAL
MINNESOTA THIS AFTERNOON...WITH RADAR HIGHER RETURNS WELL SOUTH OF
THE CWA.
HIGH PRESSURE WILL MOVE QUICKLY THROUGH THE NORTHLAND
TONIGHT...WITH WAA INCREASING OVERNIGHT AHEAD OF AN AREA OF LOW
PRESSURE. WE HAVE A CHANCE FOR LIGHT SNOW LATER TONIGHT OVER
NORTHWEST AREAS...AND INCREASED POPS TO LIKELY BETWEEN 09-12Z OVER
KOOCHICHING COUNTY. THE WAA AND WEAK SHORT WAVE WILL CONTINUE TO
IMPACT FAR NORTHERN AREAS WEDNESDAY...AND WE HAVE INCREASED POPS
TO LIKELY AS ACCUMULATIONS UP TO TWO INCHES WILL BE POSSIBLE IN
SPOTS. TEMPERATURES TONIGHT WILL BE A CHALLENGE...AS THEY WILL BE
HIGHLY DEPENDENT ON CLEARING. WE DID DROP THEM MOST AREAS...HAVE
SOME WELL BELOW ZERO OVER NORTHEAST MINNESOTA. EVENING SHIFT WILL
HAVE TO MONITOR CLOUD TRENDS CLOSELY...AS WE MAY NOT BE COLD
ENOUGH IF IT CLEARS LONGER THAN ANTICIPATED. HIGHS WEDNESDAY
WILL BE WARMER THAN TODAY...WITH SOME AREAS REACHING AROUND THIRTY
OVER NORTHWEST WISCONSIN.
CONFIDENCE WEDNESDAY NIGHT IS LOWER THAN AVERAGE REGARDING SNOW
POTENTIAL. NAM WAS SHOWING A WEAK CIRCULATION AT 850MB AND
FORECASTS SOME LIGHT SNOW OVER THE FAR NORTH. THE MODELS ARE NOT
IN VERY GOOD AGREEMENT DURING THIS PERIOD. WE KEPT A MENTION OF
LIGHT SNOW OVER THE NORTH...AND EXPANDED A BIT SOUTH OVER OUR
WESTERN COUNTIES. IF THE MODELS TREND TOWARD THE NAM...WE WILL
NEED HIGHER POPS FOR SOME LIGHT SNOW ACCUMULATIONS OVER THE WEST
AND NORTHERN CWA.
.LONG TERM...THURSDAY - MONDAY.
THE NORTHLAND SHOULD FIND ITSELF THURSDAY MORNING WITH A STATIONARY
FRONT NEAR OR SOUTH OF THE FA. THERE MAY BE SOME LIGHT SNOW ACROSS
THE NORTHERN FA THURSDAY ASSOCIATED WITH PLENTIFUL LOW CLOUDS NORTH
OF THE FRONT. HIGH PRESSURE IN CANADA WILL BEGIN TO EXERT GREATER
INFLUENCE ON THE NORTHLAND THURSDAY NIGHT...PROVIDING DRY WEATHER
THROUGH FRIDAY NIGHT. THE MODELS ARE LATCHING ONTO A STRONG LOW
PRESSURE SYSTEM MOVING FROM THE CENTRAL PLAINS TO UPPER MIDWEST ON
SATURDAY. THIS SYSTEM COULD BRING SIGNIFICANT SNOWFALL TO PARTS OF
THE FA...ESPECIALLY THE SOUTHEASTERN FA WHICH WILL BE IN BETTER
PROXIMITY TO THE SYSTEM. TEMPERATURES THROUGH THE PERIOD SHOULD BE
NEAR OR SLIGHTLY ABOVE NORMAL.
&&
.AVIATION...18Z TAFS
IFR/MVFR CONDITIONS ACROSS NE MINNESOTA AND NW MINNESOTA ARE
EXPECTED TO CONTINUE THROUGH THIS AFTERNOON AND INTO EARLY THIS
EVENING. CIGS WILL LIKELY RANGE FROM 1500 TO 3000 FT...AND THE
-SN WILL OCCASIONALLY REDUCE VIS TO IFR. THE SNOW SHOULD BEGIN TO
SUBSIDE LATER THIS AFTERNOON. THE CLOUDS WILL BEGIN TO CLEAR AT
KINL BY MID AFTERNOON...AND THEN AT OTHER TERMINALS LATE THIS
AFTERNOON AND EARLY THIS EVENING. EXPECT THE 5 TO 10 KNOT W TO SW
WINDS TO BECOME S TO SE TONIGHT. KINL COULD SEE MVFR CIGS
REDEVELOP LATE TONIGHT AND TOMORROW MORNING...BUT VFR CONDITIONS
ARE LIKELY TO RETURN TO KDLH/KHIB/KBRD/KHYR TONIGHT.
&&
.POINT TEMPS/POPS...
DLH 3 28 20 29 / 10 10 10 20
INL -9 23 8 19 / 60 70 30 20
BRD -5 29 17 28 / 10 10 20 10
HYR 2 32 22 33 / 20 10 10 0
ASX 5 33 25 35 / 20 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 10 PM CST THIS EVENING FOR LSZ140.
&&
$$
SHORT TERM...MELDE
LONG TERM....GROCHOCINSKI
AVIATION...GROCHOCINSKI
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
613 PM MST WED DEC 12 2012
.SHORT TERM...VALID FOR THU AND FRI...
DID A QUICK UPDATE TO THE FORECAST THIS EVENING TO REDUCE POPS
FROM KBIL W AND TO ADD RAIN TO THE FORECAST. RADAR AND OBSERVATION
TRENDS SHOWED THE WESTERN EDGE OF PRECIPITATION WAS ADVANCING
RAPIDLY E TOWARD KBIL THIS EVENING. IN ADDITION...TEMPERATURES IN
THE 30S WERE SUPPORTING A MIX OF RAIN AND SNOW OVER PORTIONS OF
THE AREA...SO ADJUSTED EVENING PRECIPITATION TYPE. TWEAKED WINDS
THROUGH 03Z TO MATCH RECENT LAPS OBSERVATIONS AS WELL. REMAINDER
OF FORECAST LOOKED GOOD. AREAS THAT RECEIVED PRECIPITATION LOOKED
PRIMED FOR FOG BASED ON TEMPERATURE/DEWPOINT SPREADS. WILL
CONTINUE TO MONITOR THE FOG POTENTIAL THIS EVENING. ARTHUR
.PREVIOUS DISCUSSION...
A CHALLENGING FORECAST DEALING WITH POTENTIAL LINGERING SNOW THIS
EVENING WILL EASE INTO A QUIET AND SEASONABLY COOL PERIOD FOR THE
END OF THE WEEK BENEATH SPLIT FLOW ALOFT.
TONIGHT...EXTRAPOLATING THE DISTINCT DRYING OBSERVED ON AFTERNOON
MOISTURE CHANNEL IMAGES IN ID AND SOUTHWESTERN MT SUGGESTS AN END
TO PRECIPITATION AT LIVINGSTON BY 00 UTC...AND AROUND BILLINGS BY
ABOUT 03 UTC. OF COURSE...THE LEADING EDGE OF THAT DRYING IS TIED
TO A STEEPENING OF MID-LEVEL LAPSE RATES...SO UPSTREAM SNOW RATES
HAVE ACTUALLY INTENSIFIED FOR A SHORT TIME JUST AHEAD OF IT. WITH
THAT IN MIND...WE KEPT LIKELY POPS IN PLACE EVEN AT BILLINGS THIS
EVENING...EVEN THOUGH THE MAIN BAND OF MOISTURE UP THROUGH 22 UTC
HAS BEEN NORTH OF THE CITY. THE SHIELD OF PRECIPITATION WHICH HAS
BEEN GOING ON NORTH AND EVEN NORTHEAST OF BILLINGS TODAY SEEMS TO
BE DRIVEN BY SOME WEAK FRONTOGENESIS...BUT THE BETTER FORCING HAS
BEEN OBSERVED ON ISENTROPIC SURFACES...WITH PRESSURE ADVECTION AT
THE 290 K LEVEL SIGNIFICANT FROM ROUNDUP TO FORSYTH. THIS FORCING
ON ISENTROPIC SURFACES EVEN DIMINISHES TOWARD 00 UTC...BUT WE DID
LEAVE IN LIKELY POPS ROUGHLY ALONG AND NORTH OF INTERSTATE 94 FOR
THE EVENING BASED ON RECENT RADAR TRENDS...THE LAST FEW HRRR RUNS
AND THE 12 UTC GFS...WHICH HAS SIMULATED THIS MOISTURE WELL. SOME
ROADS COULD BE SLICK...MUCH LIKE HAS BEEN SEEN TODAY IN THE SPOTS
THAT HAVE RECEIVED SNOW INSTEAD OF A MIX OF RAIN AND SNOW...WHICH
IS WHY WE WILL CONTINUE MENTIONING SOME TRAVEL IMPACTS OVER PARTS
OF THE AREA INTO THE EVENING. WE DO NOT ANTICIPATE ENOUGH SNOW TO
NECESSITATE A WINTER WEATHER ADVISORY ANYWHERE...BUT WE WILL NEED
TO KEEP A CLOSE EYE ON THAT POTENTIAL THIS EVENING.
BEYOND MIDNIGHT...WE EXPECT MOST AREAS TO BE DRY...MUCH LIKE MOST
12 UTC GUIDANCE SUGGESTS. WE LINGERED SOME 20 AND 30 PERCENT POPS
IN SOUTHEASTERN MT THOUGH. THE 12 UTC MET GUIDANCE SUGGESTS THERE
MAY BE SOME FOG WHERE PRECIPITATION FELL TODAY...AND BUFKIT-BASED
SOUNDING TOOLS ALSO SUPPORT THAT RISK. THUS...PATCHY FOG IS SHOWN
IN THE FORECAST AFTER 06 UTC FOR HARLOWTON...ROUNDUP...MILES CITY
AND EVEN BAKER. IF A TENTH OF AN INCH OF MOISTURE OR MORE HAPPENS
TO FALL IN BILLINGS THIS EVENING...THEN WE WILL NEED TO GIVE SOME
CONSIDERATION TO ADDING FOG TO THE FORECAST THERE TOO.
THU...WEAK LOW- AND MID-LEVEL WARM AIR ADVECTION WILL OCCUR...BUT
FORECAST SOUNDINGS SUGGEST BOUNDARY LAYER MIXING WILL BE SEVERELY
LIMITED BENEATH SPLIT FLOW ALOFT. THIS ENVIRONMENT WILL FAVOR THE
PERSISTENCE OF ANY FOG THAT FORMS TONIGHT INTO THU MORNING...WITH
SOME POTENTIAL FOR STRATUS TO LINGER OVER SOUTHEASTERN MT ALL DAY
LIKE THE 12 UTC MET MOS SUGGESTS AT MILES CITY AND BAKER. WE KEPT
HIGHS IN THOSE SPOTS COOLER THAN THE 12 UTC BIAS-CORRECTED FLAVOR
OF THE MULTI-MODEL CONSENSUS IN RESPECT TO THAT POTENTIAL...WHILE
INCREASING HIGHS SLIGHTLY IN PLACES LIKE BILLINGS IN ORDER TO TAG
ALONG WITH THAT GUIDANCE WHERE SUNSHINE IS EXPECTED. FINALLY...WE
MAINTAINED CONTINUITY IN SHOWING SOME SLIGHT CHANCE POPS UNTIL 18
UTC OVER SOUTHEASTERN MT AHEAD OF THE AXIS OF THE NORTHERN STREAM
500-HPA TROUGH...BUT CONFIDENCE IN PRECIPITATION IS VERY LOW.
FRI...LOW-LEVEL FLOW WILL BECOME MORE SOUTHWESTERLY IN ADVANCE OF
A MODEST SURFACE COLD FRONT THAT THE 12 UTC GFS...NAM...AND ECMWF
ALL SWING THROUGH THE AREA FRI EVENING. THIS SCENARIO SHOULD HELP
ADD A FEW MORE DEGREES F TO HIGHS OVER THOSE EXPECTED THU...WHICH
IS WHAT THE 12 UTC BIAS-CORRECTED MULTI-MODEL CONSENSUS PICKED UP
ON AS WELL. THE FRONTAL PASSAGE TIED TO A WEAK 500-HPA SHORT WAVE
IN THE NORTHERN STREAM OF THE WESTERLIES LOOKS DRY. HOWEVER...ONE
AREA WHERE WE MAY NEED TO CONSIDER SOME LOW POPS DOWN THE ROAD IS
ALONG THE FOOTHILLS BY LATE FRI NIGHT AS WEAK UPSLOPE DEVELOPS AS
A SURFACE HIGH DROPS INTO CENTRAL AND EASTERN MT. THERE WAS A BIT
OF A SIGNAL IN THE 12 UTC GFS FOR THAT...BUT NOT ENOUGH FOR US TO
PUT LOWER-ELEVATION POPS IN THE FORECAST YET. THE 09 UTC SREF WAS
MORE AGGRESSIVE WITH SOME LIGHT PRECIPITATION IN SOUTH CENTRAL MT
LATE FRI NIGHT...BUT IT IS ALSO AN OUTLIER SOLUTION. SCHULTZ
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
DRY CONDITIONS WILL PREVAIL FOR MOST LOCATIONS ON SATURDAY. AN
UPPER-LEVEL TROUGH WILL DIVE SOUTH ACROSS THE REGION DURING THIS
TIME. THE STRONGEST FORCING SHOULD TRACK SOUTH OF THE CWA. THE
FIRST IN A SERIES OF DISTURBANCES WILL MOVE ACROSS THE CWA ON
SUNDAY. BROAD-BRUSHED LOW POPS DURING THIS TIME. A SECOND WAVE
WILL TRACK ACROSS THE CWA ON MONDAY. AGAIN...KEPT POPS LOW AND
BROAD-BRUSHED. TUESDAY WILL GENERALLY BE DRY. A THIRD WAVE WILL
IMPACT THE CWA TUESDAY NIGHT INTO WEDNESDAY. BLENDED MAX/MIN
TEMPERATURES WITH THE BEST-PERFORMING 12Z GUIDANCE...ALLBLEND /
MOSGUIDE. TEMPERATURES WILL GENERALLY BE SEASONAL THROUGHOUT THE
PERIOD. BRS
&&
.AVIATION...
PRECIPITATION WILL CONTINUE OVER THE MOUNTAINS THROUGHOUT THE TAF
PERIOD. PRECIPITATION WILL CONTINUE OVER THE PLAINS THROUGH
TONIGHT. EXPECT BRIEF MVFR/IFR CONDITIONS. PRECIPITATION WILL
DIMINISH OVERNIGHT. PATCHY FOG WILL BE POSSIBLE EARLY THURSDAY
MORNING. VFR CONDITIONS WILL PREVAIL ON THURSDAY. BRS
&&
.PRELIMINARY POINT TEMP/POPS...
THU FRI SAT SUN MON TUE WED
-----------------------------------------------------------
BIL 023/040 021/041 020/037 019/038 021/036 024/040 021/035
41/B 01/U 11/B 02/J 22/J 11/B 22/J
LVM 022/037 019/040 018/033 024/035 019/033 026/036 020/034
41/B 01/B 11/B 12/W 22/J 11/N 22/J
HDN 023/038 017/039 016/035 015/037 019/037 019/040 018/036
51/B 00/B 11/B 01/B 22/J 11/B 22/J
MLS 021/033 016/035 018/032 015/035 018/036 019/036 020/035
72/J 00/B 00/B 01/B 12/J 11/B 22/J
4BQ 019/036 017/037 017/034 015/036 017/036 018/036 018/037
22/J 00/B 00/B 01/U 12/J 11/B 22/J
BHK 019/031 013/036 016/031 015/033 016/033 017/035 018/036
52/J 00/B 00/B 01/B 12/J 11/B 22/J
SHR 019/036 016/037 013/033 015/035 015/034 017/037 016/032
20/B 00/B 11/B 01/B 22/J 11/B 22/J
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1250 PM EST TUE DEC 11 2012
.SYNOPSIS...
A WESTERLY FLOW OF SEASONABLY COLD AIR WILL PREVAIL THROUGH MID-
WEEK...ALONG WITH MAINLY DRY WEATHER...AS HIGH PRESSURE GRADUALLY
BUILDS INTO THE REGION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
953 AM UPDATE...
STRONG COLD AIR ADVECTION CONTINUES THIS MORNING. LOW LEVEL DRY
AIR AND SHEAR IS WORKING TO UNDERMINE ATTEMPTS AT LES OFF OF
ONTARIO, SO CONTINUE TO EXPECT LITTLE IN THE WAY OF SNOW
ACCUMULATION.
TEMPS WON`T RISE MORE THAN A FEW DEGREES FROM CURRENT LEVELS, PER
PREVIOUS FORECAST. WE HAVE INCREASED SKY COVER IN GRIDS THROUGH
THIS EVENING HOWEVER, AS DENSE CLOUD COVER EXTENDS WELL INTO
ONTARIO PROVINCE AND OHIO. LATEST RAP SOUNDINGS SUGGEST MAINLY
CLOUDY SKIES FOR INTERIOR FA THROUGH MIDNIGHT.
4 AM TUE UPDATE... MAIN PCPN SHIELD CONTS TO QUICKLY EXIT EARLY
THIS MRNG...AS AN UPR-LVL WAVE LIFTS INTO NEW ENG...AND A SFC COLD
FRNT PUSHES OFF THE EAST COAST.
IN THE WAKE OF THE AFOREMENTIONED SYSTEMS...A W TO NW FLOW AND STG
LOW-LVL CAA WILL PREVAIL FOR THE REST OF THE MRNG HRS.
HOWEVER...DESPITE THIS SYNOPTIC SET-UP...THE LAKE RESPONSE SHOULD
BE LIMITED...AS PRONOUNCED DRY ADVECTION OCCURS ABV 900 MB...AND
THE MIXED LYR FLOW REMAINS FAIRLY SHEARED IN A DIR SENSE.
THUS...WE EXPECT NOTHING MORE THAN SCTD -SHSN/FLRYS...WITH LIMITED
ACCUMS (UNDER AN INCH) ACRS THE MOHAWK VLY/SRN TUG HILL RGN.
FROM THE TWIN TIERS SWD...AM CLDS SHOULD BREAK FOR SOME AFTN
SUNSHINE...WITH STG DRYING/DVM AT PLAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
415 AM UPDATE... QUIET WX TO PREVAIL THIS PD.
WRLY LOW-LVL FLOW PERSISTS TNT...WED...AND INTO WED EVE.
AGN...THOUGH...SHALLOW MOIST/POOR DZ MECHANICS AND DIR SHEAR IN
THE VERTICAL SHOULD SERIOUSLY MUTE ANY LAKE RESPONSE. THE "BEST"
COVERAGE OF SHSN COULD OCCUR WED AFTN INTO THE EARLY EVE IN OUR
FAR NRN ZNS...AS A PROGRESSIVE NRN STREAM UPR WAVE COMES
THROUGH...ALG WITH A WEAK SFC TROUGH. VERY MINOR ACCUMS...IF
ANY...ARE FORESEEN.
BY THU...RIDGING COMES IN...ALG WITH BACKING LOW-LVL FLOW AND WAA.
THUS...HIGH TEMPS SHOULD MODERATE INTO THE LWR 40S MANY LOCALES BY
THU AFTN.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
XTNDD PD BEGINS WIL A FLAT RDG OVER THE MID ATLANTIC AND A WLY
FLOW OVER THE FCST AREA. A LOW DVLPG OVER THE WRN GREAT LAKES WILL
BEGIN TO PUSH MOISTURE INTO THE AREA LATE SAT...CONTG THRU THE END
OF THE PD. SYSTEM IS A SLOW MVR WITH A CLSD UPR LOW...AND DFCLT TO
FCST AS THE DETAILS OF A CSTL DVLPMT LATE IN THE PD ARE STILL
FUZZY. IN ANY EVENT...MODELS ARE IN SOMEWHAT BETTER AGREEMENT AND
HAVE TRENDED TWRD A COOLER SOLN AS A CONFLUENT UPR FLOW OVER NEW
ENG BLDS A SFC HIPRES NORTHEAST OF THE AREA KEEPING COLDER AIR IN
PLACE. THIS WILL CAUSE MIXED PCPN AT TIMES AND THE LOW MEANDERS
EWRD THRU THE PD.
GNRLY FLWD HPC GUID THRU THE PD WHICH WAS CLOSER TO THE MEX GUID
THIS TIME ARND...LDG TO HIER CONFIDENCE IN THE TEMP FCST. CHANCE
POPS THUR THE PD WERE ALSO IN BETTER AGREEMENT.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
WLY FLOW OFF THE GREAT LAKES IS KEEPING LL MOISTURE IN THE AREA
THIS AFTN. THIS HAS RESULTED IN MSTLY MVFR CIGS ALIONG WITH SOME
VERY LGT SNOW SHWRS. MDL SNDG FCSTS SHOW LTL CHG OVRNGT...WITH
PERHAPS EVEN SOME LWRG OF CIGS AS WE LOSE MIXING AND WINDS GO LGT.
XCPTN WILLBE AT AVP AS SOMEWHAT DRIER AIR MAY RESULT IN A SCT CLD
DECK. AFT 12Z...FLOW BWECOMES MORE SWLY AND STRENGTHENS WHICH MAY
BRING SOME LE INTO RME...OTRW THIS FLOW WILL BEGIN A SLOW IMPRVMT
IN CONDS THRU THE END OF THE PD...AND BEYOND.
OUTLOOK...
WED NGT-SAT...VFR.
SUN...MVFR/IFR IN RAIN AND SNOW.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MLJ
NEAR TERM...DJP/MLJ
SHORT TERM...MLJ
LONG TERM...DGM
AVIATION...DGM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
951 AM EST TUE DEC 11 2012
.SYNOPSIS...
A WESTERLY FLOW OF SEASONABLY COLD AIR WILL PREVAIL THROUGH MID-
WEEK...ALONG WITH MAINLY DRY WEATHER...AS HIGH PRESSURE GRADUALLY
BUILDS INTO THE REGION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
953 AM UPDATE...
STRONG COLD AIR ADVECTION CONTINUES THIS MORNING. LOW LEVEL DRY
AIR AND SHEAR IS WORKING TO UNDERMINE ATTEMPTS AT LES OFF OF
ONTARIO, SO CONTINUE TO EXPECT LITTLE IN THE WAY OF SNOW
ACCUMULATION.
TEMPS WON`T RISE MORE THAN A FEW DEGREES FROM CURRENT LEVELS, PER
PREVIOUS FORECAST. WE HAVE INCREASED SKY COVER IN GRIDS THROUGH
THIS EVENING HOWEVER, AS DENSE CLOUD COVER EXTENDS WELL INTO
ONTARIO PROVINCE AND OHIO. LATEST RAP SOUNDINGS SUGGEST MAINLY
CLOUDY SKIES FOR INTERIOR FA THROUGH MIDNIGHT.
4 AM TUE UPDATE... MAIN PCPN SHIELD CONTS TO QUICKLY EXIT EARLY
THIS MRNG...AS AN UPR-LVL WAVE LIFTS INTO NEW ENG...AND A SFC COLD
FRNT PUSHES OFF THE EAST COAST.
IN THE WAKE OF THE AFOREMENTIONED SYSTEMS...A W TO NW FLOW AND STG
LOW-LVL CAA WILL PREVAIL FOR THE REST OF THE MRNG HRS.
HOWEVER...DESPITE THIS SYNOPTIC SET-UP...THE LAKE RESPONSE SHOULD
BE LIMITED...AS PRONOUNCED DRY ADVECTION OCCURS ABV 900 MB...AND
THE MIXED LYR FLOW REMAINS FAIRLY SHEARED IN A DIR SENSE.
THUS...WE EXPECT NOTHING MORE THAN SCTD -SHSN/FLRYS...WITH LIMITED
ACCUMS (UNDER AN INCH) ACRS THE MOHAWK VLY/SRN TUG HILL RGN.
FROM THE TWIN TIERS SWD...AM CLDS SHOULD BREAK FOR SOME AFTN
SUNSHINE...WITH STG DRYING/DVM AT PLAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
415 AM UPDATE... QUIET WX TO PREVAIL THIS PD.
WRLY LOW-LVL FLOW PERSISTS TNT...WED...AND INTO WED EVE.
AGN...THOUGH...SHALLOW MOIST/POOR DZ MECHANICS AND DIR SHEAR IN
THE VERTICAL SHOULD SERIOUSLY MUTE ANY LAKE RESPONSE. THE "BEST"
COVERAGE OF SHSN COULD OCCUR WED AFTN INTO THE EARLY EVE IN OUR
FAR NRN ZNS...AS A PROGRESSIVE NRN STREAM UPR WAVE COMES
THROUGH...ALG WITH A WEAK SFC TROUGH. VERY MINOR ACCUMS...IF
ANY...ARE FORESEEN.
BY THU...RIDGING COMES IN...ALG WITH BACKING LOW-LVL FLOW AND WAA.
THUS...HIGH TEMPS SHOULD MODERATE INTO THE LWR 40S MANY LOCALES BY
THU AFTN.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
4 AM UPDATE...
NOT MANY CHANGES TO THE EXTENDED. MAIN FOCUS WILL BE ON THE
SATURDAY NIGHT THROUGH SUNDAY PERIOD WITH THE POTENTIAL OF MIXED
PRECIP ACROSS THE AREA. WHILE THE 0Z GFS AND EURO DIFFER ON WHEN
THE PRECIP ARRIVES IN OUR AREA LATE SATURDAY NIGHT/EARLY
SUNDAY...BOTH MODELS ARE CONSISTENT IN SHOWING ENOUGH COLD AIR
AROUND FOR A WINTRY MIX FOR PART OF SUNDAY. MAIN PLAYER WILL BE A
1030 MB HIGH REMAINING ANCHORED OVER QUEBEC WHICH WILL HELP TO
LOCK ANY COLD AIR AROUND WHILE A LOW PRESSURE SYSTEM MOVES OUT OF
THE OHIO VALLEY. IT APPEARS WE SHOULD HAVE ENOUGH COLD AIR AROUND FOR
AT LEAST A BRIEF WINTRY MIX OVER MOST OF THE AREA SUNDAY. IT MAY
LAST MUCH LONGER OVER THE NORMALLY COLDER SPOTS OVER THE FAR EAST
WITH BOTH MODELS SHOWING 925 TEMPS BELOW 0C THROUGH 0Z MONDAY. IF
THIS TREND CONTINUES ADDITIONAL WORDING MAY BE ADDED TO THE HWO IN
THE COMING DAYS. THE PREVIOUS AFD IS BELOW...
THU THRU SAT PD DOMINATED BY A FLAT RDG WITH NEAR OR
SLGTLY ABV NRML TEMPS. DRY AIR WITH THE RDG WILL KEEP SKIES PTLY
CDY AT WORST...WITH WITH WLY FLOW AND MRGNL TEMPS KEEPING ANY LE
OUT OF THE AREA. CHGS BEGIN LATE SAT INTO SUN AS A SYSTEM MVES
INTO THE MIDWEST. CNSDRBL DFRNCS BETWEEN THE OPERATIONAL MODELS
WITH THE ECMWF WINDING UP A DEEPER LOW WEST OF THE AREA PUMPING UP
THE RDG AND DVLPG STRONGER WAA. THE GFS MORE QUICKLY TRANSFERS
ENERGY TO THE ERN SYSTEM KEEPING THE AREA COLDER AND BRINGING A
CHANCE OF MIXED PCPN. HPC GUID TENDS TO FOLLOW THE EURO SOLN AND
IS MILDER. FOR THE GRIDS...LEANED TWRDS HPC AND THE EURO BUT DID
LWR TEMPS A FEW DEGREES TO BETTER BLEND WITH SURROUNDING OFFICES
WHICH SEEM TO FVR THE GFS. COOLER MON WITH AN UPR LOW NORTH OF THE
LAKES AND A NW FLOW...BUT STILL NEAR SEASONAL TEMPS.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
640 AM UPDATE...
LOW END MVFR CIGS THIS MORNING WILL GRADUALLY RISE TO VFR BY LATE
MORNING DRIER AIR MOVES IN FROM THE WEST. THIS PROCESS WILL BE
FASTEST AT KAVP WITH VFR POSSIBLE IN THE NEXT HOUR OR TWO. FARTHER
NORTH A BIT MORE TRICKY OF A CALL. BASED ON MODEL SOUNDINGS WE
SHOULD BE SEEING VFR CIGS WITHIN THE HOUR. HOWEVER WE HAVE PLENTY
OF MVFR BACK ACROSS WESTERN NY AND AS THE FLOW BACKS MORE INTO THE
WEST...IT MAKES SENSE THAT THE CIGS MAY TAKE LONGER TO RISE THAN
WHAT THE MODELS INDICATE. BKN CIGS AROUND 5KFT THIS AFTERNOON WITH
A CLEARING SKY EXPECTED TONIGHT.
WNW WINDS 5 T0 1O KTS THROUGH THIS AFTERNOON BECOMING
LIGHT/VARIABLE TONIGHT.
OUTLOOK...
TUE NGT-SAT...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MLJ
NEAR TERM...DJP/MLJ
SHORT TERM...MLJ
LONG TERM...DGM/HEDEN
AVIATION...HEDEN
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
1229 AM EST TUE DEC 11 2012
.SYNOPSIS...
WIDESPREAD LIGHT RAIN WILL MIX WITH AND CHANGE TO LIGHT SNOW
LATER THIS EVENING BEFORE TAPERING OFF OVERNIGHT. A FEW INCHES
ARE POSSIBLE...MAINLY OVER THE HIGHER TERRAIN OF THE NORTHERN
MOUNTAINS. SEASONABLY COLD AND MAINLY DRY WEATHER IS THEN
EXPECTED FROM TUESDAY ONWARD INTO NEXT WEEKEND AS HIGH PRESSURE
DOMINATES REGIONAL WEATHER CONDITIONS. SEASONABLY COLD
TEMPERATURES TUESDAY INTO WEDNESDAY...WILL MODERATE BY LATE WEEK
INTO NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 919 PM EST MONDAY...SFC OBS INDICATE SLK/WNK AND LKP ACRS
THE DACKS HAVE CHANGED TO SNOW WITH TEMPS NEAR FREEZING ATTM.
LLVL CAA CONTS FROM NW TO SE ACRS OUR CWA THIS EVENING WITH
WHITEFACE AT NEAR 85H DOWN TO 23F. LITTLE SNOW ACCUMULATION HAS
BEEN OBSERVED SO FAR VIA WEB CAMS OR SPOTTER REPORTS. IN
ADDITION...DRIER AIR CONTS TO ALSO ADVECT INTO OUR CWA THIS
EVENING ON NW TO NORTH WINDS BEHIND THE SFC BOUNDARIES. THIS HAS
RESULTED IN A DECREASE IN AREAL COVERAGE/INTENSITY OF PRECIP ACRS
NORTHERN NY AS EXPECTED...WITH MOST OF THE SLV DRY ATTM. HAVE
DECREASED POPS ACRS THE SLV THRU THE REST OF TONIGHT BASED ON
RADAR TRENDS. ELSEWHERE...1000 TO 700MB RH CONTS THRU 05Z ACRS
THE DACKS AND UNTIL 09Z FOR MOST OF CENTRAL/NORTHERN VT
MTNS...SUPPORTING SOME LIGHT SNOWFALL. IN ADDITION...SOME BLOCKED
FLW AND ADDITIONAL LAKE CHAMPLAIN MOISTURE INTERACTION WL HELP TO
KEEP SNOW ACTIVITY GOING A BIT LONGER ACRS THE WESTERN
SLOPES/EASTERN CPV EARLY TUESDAY MORNING. STILL THINKING A
DUSTING TO A COUPLE OF INCHES WITH SOME ISOLATED AREAS ALONG THE
WESTERN SLOPE GETTING 3 INCHES OR SO BY MORNING. LITTLE SNOW
ACCUMULATION IS EXPECTED ON THE WESTERN SIDE OF THE CPV AND CT
RIVER VALLEY. WITH A DUSTING TO 2 INCHES POSSIBLE FOR THE MTNS OF
THE NEK BY TUES AM. TEMPS WL BE TRICKY WITH SHARP NW TO SE
THERMAL GRADIENT ASSOCIATED WITH CAA ACRS OUR CWA. THINKING MID
TEEN SLV/SLK TO L/M30S VSF. AS TEMPS SLOWLY DROP BLW FREEZING
AREAS OF PATCHY BLACK ICE WL BE POSSIBLE AND COULD CREATE A FEW
SLICK SPOTS DURING THE MORNING COMMUTE.
OVERALL FCST IN GOOD SHAPE WITH ONLY SOME MINOR ADJUSTMENTS BASED
ON CRNT TRENDS. LATEST SFC ANALYSIS PLACES LOW PRES NORTH OF THE
BORDER WITH ONE COLD FRNT ACRS THE CPV ATTM...AND ANOTHER ONE
APPROACHING THE SLV...WITH MUCH COLDER AIR BEHIND THIS FRNT. THE
FIRST FRNT HAS RESULTED IN AN OVERALL INCREASE IN AREAL
COVERAGE/INTENSITY OF RAIN SHOWERS ACRS THE CPV AND PARTS OF
CENTRAL/NORTHERN VT THIS EVENING...WITH ADDITIONAL SHOWERS ACRS
NORTHERN NY. WL CONT TO MENTION POPS AT 100% THRU 00Z...THEN
START TO TAPER POPS OFF FROM THE SLV EASTWARD. WHITEFACE OBS DOWN
TO 28F...WHICH INDICATES THE COLDER AIR IS MOVING IN ALOFT...BUT
SFC TEMPS STILL REMAIN ABOVE 0C ACRS OUR CWA...WHICH WL MAKE RAIN
TO SNOW AND AMOUNT OF ACCUMULATION DIFFICULT TONIGHT. BASED ON
OBS AND LATEST RAP MODEL...THINKING CHANGE OVER TO SNOW WL OCCUR
AT SLK BTWN 01Z-02Z...MPV/BTV BY 05Z...AND ACRS EASTERN/SOUTHERN
VT AFT 06Z. NEXT QUESTION WL BE AMOUNT OF RH LEFTOVER...WHICH
RAP/NAM SHOW QUICKLY DISSIPATING AS THERMAL PROFILES BECM COLD
ENOUGH FOR SNOW. THINKING THE COMBINATION OF UPSLOPE FLW...SOME
1000 TO 700MB RH...AND FAVORABLE BLOCKING/CONVERGENCE ACRS THE
CPV...WL RESULT IN A PERIOD OF SNOW SHOWERS WITH SOME
ACCUMULATIONS...WHICH CRNT FCST HAS COVERED NICELY. THINKING
DUSTING TO AN INCH BTV/PBG...AROUND 2" FOR ESSEX/JERICHO...AND UP
TO 3" POSSIBLE NEAR UNDERHILL/STOWE/JAY PEAK BY 12Z TUES AND A
DUSTING TO SEVERAL INCHES FOR THE DACKS...AND ONLY LIGHT AMOUNTS
CT RIVER VALLEY AND SLV. WL CONT TO MONITOR CRNT TRENDS FOR
POTENTIAL ADJUSTMENTS...BUT OVERALL FCST IN GOOD SHAPE.
FORECAST REMAINS ON TRACK FOR TONIGHT WITH NEAR TERM CHALLENGES
BEING THE OVERALL COVERAGE OF PCPN...AND THE EXTENT TO WHICH
COOLING NEAR-SFC THERMAL PROFILES OVERNIGHT LEAD TO MINOR
SNOWFALL ACCUMULATIONS. PARENT LOW PRESSURE SYSTEM RESPONSIBLE
FOR THIS AFTERNOON`S RAIN/SHOWERS CURRENTLY PASSING NORTHEAST
THROUGH THE SLV NEAR MONTREAL AND EXPECT THIS TREND TO CONTINUE
TONIGHT. A GENERAL REBLOSSOMING OF RAINFALL IS NOW OCCURRING
ACROSS THE REGION ASSOCIATED WITH WEAK SFC WAVE RIDING NORTHEAST
ALONG LEAD FRONTAL BOUNDARY FROM CENTRAL PA INTO CENTRAL/WRN NY
STATE UP TO THE PARENT LOW. AN ADDITIONAL 0.15 TO 0.25 INCHES OR
SO IS EXPECTED WITH THIS ACTIVITY THROUGH THE 00-02Z TIME FRAME
AS THE FRONT SWINGS THROUGH THE REGION. TEMPERATURES QUITE MILD
THROUGH EARLY EVENING...NOTED BY MANY READINGS IN THE 40S AND
INTO LOWER AND MID 50S IN SOME CASES AS OF 3 PM.
OF ADDITIONAL INTEREST IS THE PRIMARY POLAR FRONT STILL
STATIONARY FURTHER OFF TO THE NORTHWEST BEHIND THE LEADING FRONT.
MUCH COLDER AIR BACK BEHIND THIS SECONDARY BOUNDARY AND AS
AFOREMENTIONED SFC LOW SWINGS AWAY TO THE NORTHEAST...THIS FRONT
WILL SURGE SOUTHEAST AND OVERTAKE THE LEAD FRONT LATER THIS
EVENING. FLOW TRENDS NORTHWEST BEHIND THIS PASSAGE WITH STRONG
CAA SETTING UP AS 925-850 MB THERMAL PROFILES CRASH AFTER
MIDNIGHT. ALL RELIABLE MODELS SHOW AT LEAST SOME CHANGEOVER TO
SNOW DURING A 3-6 HOUR PERIOD FROM ABOUT 02Z-07Z AS THIS OCCURS
AND BACK EDGE OF PCPN EXITS TO THE EAST. LOW FROUDE NUMBER
PROFILES SUPPORT AMPLE LOW LEVEL BLOCKING FAVORING THE WESTERN
SLOPES AS MEAN PBL WINDFLOW TRENDS NORTHWEST. HOWEVER...
PROBLEMATIC ISSUES ON POTENTIAL ACCUMULATIONS EXIST AS
USUAL...AND MAINLY CONCERN A NARROWING COLUMNAR MOISTURE DEPTH
OVER TIME AND HOW QUICKLY THE NEAR-SFC 2M TEMPERATURES CAN COOL
AS EVIDENCED BY 12Z 3-HRLY MOS NUMBERS. AFTER USING SEVERAL
METHODS...MY BEST ESTIMATE IS FOR ONLY VERY LIGHT ACCUMULATIONS
TO OCCUR IN THE LOWER ELEVATIONS...SAY A DUSTING TO PERHAPS AN
INCH...WITH A GENERAL 1-3 INCH ACCUMULATION EXPECTED ABOVE 1 KFT
AND PERHAPS 3-5" NEAR THE SUMMIT LEVEL. TEMPERATURES TO HOLD MILD
THROUGH EARLY...THAN FALL RATHER SHARPLY LATER TONIGHT BOTTOMING
OUT FROM THE UPPER TEENS TO MID 20S NORTH AND WEST...AND UPPER
20S/LOWER 30S SOUTH/SOUTHEAST.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 317 PM EST MONDAY...REMAINDER OF THE SHORT TERM THEN TRENDS
RELATIVELY QUITE AS CANADIAN HIGH PRESSURE SETTLES ATOP THE
REGION. OTHER THAN SOME LINGERING NRN MTN FLURRIES IN THE
MORNING...EXPECTING A CHILLY DAY ON TAP FOR TOMORROW (TUESDAY) AS
925 MB TEMPERATURES CONTINUE TO FALL INTO THE -8C TO -12C RANGE
BY MID-AFTERNOON UNDER MODEST NORTHWESTERLY GRADIENT. THIS
SUPPORTS HIGHS HOLDING MAINLY STEADY IN THE 20S FOR MOST
LOCALES...THOUGH A FEW LOWER 30S POSSIBLE IN FAVORED DOWNSLOPE
REGIONS OF SOUTHERN VT.
THEREAFTER...CLEAR TO PTLY CLOUDY SKIES CONTINUE TUESDAY NIGHT
INTO WEDNESDAY NIGHT WITH AFOREMENTIONED HIGH SLIDING SLOWLY ATOP
AND EAST OF THE REGION. AFTER A CHILLY NIGHT TUESDAY NIGHT IN THE
SINGLE DIGITS TO TEENS...READINGS TO REBOUND BACK TO NEAR
SEASONAL NORMS BY WEDNESDAY AS MODEST SOUTHWESTERLY RETURN FLOW
DEVELOPS. AS MENTIONED EARLIER...MAINLY DRY WEATHER EXPECTED
DURING THESE PERIODS...THOUGH I HAVE HINTED AT A FEW FLURRIES
ACROSS THE SLV/DACKS TO ACCT FOR ANY WEAK LAKE ENHANCED ACTIVITY
THAT HI-RES MODELS SUGGEST MAY BE DRIFTING AROUND.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 317 PM EST MONDAY...FIRST HALF OF THE EXTENDED PERIOD WILL
CONTINUE TO FEATURE RATHER QUIET WEATHER THANKS TO HIGH PRESSURE
RIDGING. THINGS GET MORE INTERESTING FOR LATER IN THE WEEKEND AND
EARLY NEXT WEEK WHEN IT APPEARS A MORE UNSETTLED PATTERN WILL SET
UP. UNFORTUNATELY, THE SPREAD IN GUIDANCE IS RATHER LARGE BY THIS
POINT, SO ALTHOUGH CONFIDENCE IS MODERATE/HIGH FOR THURSDAY AND
FRIDAY, IT`S LOW/VERY LOW BY SUNDAY & MONDAY. DAILY SPECIFICS
BELOW:
THURSDAY & FRIDAY: LOW/MID LEVEL RIDGE WILL PERSIST, RESULTING IN
A COUPLE OF DRY AND FAIRLY SUNNY DAYS. TEMPERATURES WILL BE
SLIGHTLY ABOVE NORMAL BOTH DAYS -- LOTS OF 30S THURSDAY AND 30S
AND 40S (LOWER ELEVATIONS) FOR FRIDAY AS 925MB TEMPERATURES CLIMB
TO -2C TO 0C RANGE. STUCK CLOSE TO GUIDANCE FOR HIGH AND LOW
TEMPERATURES.
SATURDAY: 12Z GFS AND EURO RUNS START TO DIVERGE AT THIS POINT.
GFS INDICATES A VERY WEAK UPPER TROF AND ASSOCIATED WEAK SURFACE
LOW WILL ZIP BY TO OUR NORTH, PERHAPS PRODUCING A FEW MOUNTAIN
FLURRIES. EURO IS EVEN WEAKER WITH THE FEATURE. SHOULD END OUT TO
BE ANOTHER DRY DAY OVERALL, BUT A LITTLE COOLER THAN FRIDAY AS
THE MEAN FLOW SHIFTS MORE WEST/NORTHWEST. AGAIN, STAYED CLOSE TO
GUIDANCE FOR TEMPERATURES.
SUNDAY: MODELS FOR SEVERAL RUNS HAVE BEEN SHOWING SOME SORT OF
UPPER TROF DIGGING TO OUR WEST, WHILE SURFACE LOW PRESSURE PUSHES
OUT OF THE GREAT LAKES AND TOWARD THE COAST. ALL RUNS HAVE BEEN
DIFFERENT IN THE DETAILS. EURO HAS BEEN MORE PROGRESSIVE AND
FASTER WITH THIS, AND THE 12Z EURO IS NO DIFFERENT -- WOULD
SUGGEST LOTS OF CLOUDS AND LIGHT PRECIPITATION BREAKING OUT
SUNDAY MORNING. GFS HOLDS BACK A MORE CUT-OFF LOW FARTHER TO THE
SOUTHWEST, KEEPING THE DAY HERE DRY, AND ONLY SKIMMING THE
SOUTHERN HALF OF THE REGION WITH LIGHT PRECIPITATION SUNDAY NIGHT
AS IT SLIDES THE LOW SOUTH OF NEW ENGLAND. GIVEN OVERALL TRACK
RECORD OF EURO AND HPC`S FAVORING THAT MODEL, HAVE PAINTED IN
CHANCE LEVEL POPS FOR SUNDAY. MODEL PROFILES SUGGEST THAT THERE
COULD BE SOME MIXED PRECIPITATION, BUT THIS FAR OUT I KEPT IT TO
A SIMPLE RAIN/SNOW OPTION. TEMPERATURES -- STUCK A BIT CLOSER TO
THE EURO WHICH FEATURES MOST AREAS REACHING THE 35-40F RANGE.
GOOD DEAL OF BUST POTENTIAL HERE.
MONDAY: MODELS ARE ALL OVER THE PLACE, THOUGH ALL FEATURE SOME
SORT OF STRENGTHENING LOW PRESSURE -- WHETHER FAR SOUTHEAST OF
NEW ENGLAND (12Z GFS), EAST OF MAINE (00Z EURO), OR OVER THE MID-
ATLANTIC (12Z EURO). AT THIS POINT, BEST COURSE IS TO HAVE AT
LEAST CHANCE LEVEL POPS PAINTED IN ACROSS THE ENTIRE REGION. THE
12Z EURO TAKEN AT FACE VALUE WOULD SUGGEST A WET/WINDY/WARM
STORM. FOR TEMPERATURES, STARTED WITH THE EURO, BUT TOOK SEVERAL
DEGREES OFF. STILL ENDED UP WITH A LOT OF 40S FOR HIGHS.
I SUSPECT THE FORECASTS FOR THE WEEKEND AND EARLY NEXT WEEK ARE
GOING TO CHANGE QUITE A BIT BETWEEN NOW AND THEN...
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
THROUGH 06Z WEDNESDAY...COLD FRONT CONTINUES TO PUSH EAST ACROSS
THE NORTH COUNTRY...HAS ALREADY CLEARED MSS...SLK AND PBG...WILL
SOON CLEAR BTV. HAVE KEPT SHOWERS IN FOR A COUPLE MORE HOURS AT
RUT AND MPV. SOME MVFR CONDITIONS MAY LINGER WITH SOME LOW CLOUDS
AROUND...BUT CONDITIONS GRADUALLY IMPROVE THROUGH THE PERIOD.
OUTLOOK 06Z WEDNESDAY THROUGH SATURDAY...SURFACE HIGH PRESSURE
WILL PROVIDE THE ENTIRE REGION WITH VFR CONDITIONS.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...JMG
NEAR TERM...JMG/TABER
SHORT TERM...JMG
LONG TERM...NASH
AVIATION...NEILES
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
754 PM CST WED DEC 12 2012
.DISCUSSION...
THE MAIN CHALLENGE OVERNIGHT WILL BE SNOW POTENTIAL IN A FAIRLY
NARROW BAND ALONG THE I 94 CORRIDOR. A MID LEVEL BAND OF FGEN IN
THE 850-700MB LEVEL IS SETTING UP FROM KDIK-KBIS THIS
EVENING...AND EXPECT THIS TO PROGRESS TO THE E/NE OVERNIGHT. THE
GFS HAD THE BEST HANDLE ON THIS...AND THE RAP SLOWLY WEAKENS THIS
SNOW OVERNIGHT WITH SFC HIGH BUILDING IN. THE INHERITED POPS
REALLY LOOK GOOD WITH THE POTENTIAL FOR UP TO AN INCH OF SNOW IN A
NARROW BAND...SO WILL MAINTAIN THIS POTENTIAL. THESE SNOW BANDS
SOMETIMES DEVELOP A BIT MORE THAN MODELS INDICATE...SO WILL
CONTINUE TO MONITOR...BUT GRIDS ARE IN GOOD SHAPE. WILL RAISE
OVERNIGHT MINIMUMS IN THE NORTH AND THE SOUTH...WITH PLENTY OF
CLOUDS AND COOLING RELYING ON LOW LEVEL CAA BEHIND THE COLD FRONT.
&&
.AVIATION...
EXPECT MVFR CIGS THROUGH THE PERIOD WITH SOME LIGHT SNOW POSSIBLE
LATER TONIGHT INTO THU. WINDS SHOULD BE NORTHERLY WITH HIGH PRESSURE
BUILDING IN FROM CANADA. VSBYS COULD LOWER INTO IFR RANGE NEAR
KFAR FROM A BETTER DEFINED SNOW BAND IF IT DEVELOPS...SO WE WILL
MONITOR THIS POTENTIAL.
&&
.PREV DISCUSSION... /ISSUED 230 PM CST WED DEC 12 2012/
DISCUSSION...FORECAST CHALLENGE CONCERNS TEMPERATURES AND SNOW
CHANCES. MODELS SHOWING SOME MINOR DIFFERENCES WITH SNOW BAND LATE
TONIGHT INTO TOMORROW AND WILL CONTINUE WITH A BLEND.
NEXT WAVE PUSHING INTO WESTERN WYO IN MID LEVEL ZONAL FLOW AND WILL
IMPACT THE REGION LATE TONIGHT INTO THURSDAY. MAIN JET AXIS THROUGH
THE CENTRAL PLAINS AND UPPER SUPPORT AT THIS TIME LOOKS RELATIVELY
WEAK. THERE IS A BAND OF LOWER CONDENSATION PRESSURE DEFICIT/MODEST
ISENTROPIC LIFT AND FRONTOGENETIC FORCING GENERALLY BETWEEN HIGHWAY
2 AND I 94 FROM MIDNIGHT ON. MODELS HAVE BEEN RELATIVELY CONSISTENT
WITH THIS AND WILL INCREASE POPS. AT THIS POINT WITH RELATIVELY WEAK
ABOVE MENTIONED FORCING MECHANISMS FEEL GENERAL SNOW AMOUNTS IN THE
1-2 INCH RANGE LOOK REASONABLE AT THIS TIME INTO MID DAY THURSDAY.
BAROCLINIC ZONE SAG SLOWLY SOUTH TONIGHT HOWEVER EXTENSIVE CLOUD
LAYER SHOULD LIMIT DROP TONIGHT. COULD STILL SEE A FAIRLY
RESPECTABLE TEMPERATURE CONTRAST ACROSS THE REGION WITH COLDEST
TEMPERATURES ACROSS FAR NORTH WHERE TEMPERATURES CURRENTLY BLO
ZERO.
MODELS DIFFER ON DURATION OF -SN ALONG NARROW CORRIDOR THURSDAY
HOWEVER WOULD EXPECT BAND TO SHIFT EAST WITH WAVE REPRESENTED BY
NAM/GFS 290K ISENTROPIC SURFACE AND WILL TIME POPS ACCORDINGLY. LOW
LEVEL RH REMAINS IN PLACE SO CLOUD TRENDS WITH WAVE PASSAGE IN
QUESTION. WITH LIGHT MIXING AS SURFACE HIGH BUILDS IN TEMPERATURE
RECOVER WILL BE MINOR AND HAVE TRIMMED BACK ON MAXIMUM VALUES.
SHOULD BE QUIET REMAINDER OF WORK WEEK WITH SLIGHTLY MODERATING
THERMAL COLUMN. LOW LEVEL RH REMAINS ACROSS FA SO CLOUDS REMAIN A
QUESTION AND THIS TIME OF YEAR A MAJOR PLAYER WITH TEMPERATURES.
GEM A SIGNIFICANT OUTLIER WITH NORTHWARD EXTEND OF QPF FRIDAY NIGHT
AND WILL BE DISCARDED. NAM/ECMWF STILL CLIP FAR SE-E FA SAT AND WILL
MAKE SOME MINOR POP ADJUSTMENTS.
LONG TERM... /SAT NIGHT THROUGH WED/
LONG TERM MODELS IN REASONABLE AGREEMENT EARLY IN THE PERIOD...BUT
DIVERGE SIGNIFICANTLY FOR EARLY NEXT WEEK. STRONG LOW PRESSURE
SYSTEM EXPECTED TO LIFT OUT OF THE CENTRAL PLAINS AND INTO THE GREAT
LAKES OVER THE WEEKENDS...WITH WRAP AROUND SNOW POSSIBLY IMPACTING
MY EASTERN ZONES SAT NIGHT AND SUN. 12Z ECWMF MORE IN LINE WITH THE
00Z/12Z GFS...WHICH PULLS PRECIP OUT OF THE AREA BY NOON SUN. PREV
ECMWF KEPT LINGERING PRECIP IN THE EAST THROUGH MONDAY. GFS THEN
SIGNIFICANTLY DIVERGES FROM ECWMF WITH A CLIPPER LIKE SYSTEM MOVING
ACROSS NORTHERN TIER MON NIGHT INTO TUE. CURRENT ALLBLEND SOLUTION
CONTINUES TO KEEP A DRY FCST IN FOR TUE...BUT GFS SOLUTION WOULD
CERTAINLY BRING SNOW SNOWFALL ACROSS OUR NORTHERN ZONES MON NIGHT
AND TUE. DUE TO LOW CONFIDENCE...WILL GO WITH DRY SOLUTION.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
DK
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
256 PM CST TUE DEC 11 2012
.SHORT TERM... /TONIGHT THROUGH FRIDAY/
THE FORECAST CHALLENGE FOR THE SHORT TERM WILL BE OVERNIGHT LOWS
AND SNOWFALL AMOUNTS ACROSS THE FAR NORTHERN ZONES. MODELS ARE IN
GENERAL AGREEMENT TODAY...ALTHOUGH THE RUC HAS A MUCH BETTER
HANDLE ON CLOUDS CURRENTLY ACROSS WESTERN NORTH DAKOTA. THEREFORE
WILL USE A FORECAST BLEND.
MAJORITY OF OUR CWA IS CLEAR OR UNDER THIN STRATUS...WITH SOME
REMNANTS OF TODAYS CLOUD COVER OVER THE CENTRAL VALLEY EXTENDING
EASTWARD INTO SOUTHERN BELTRAMI COUNTY. RADAR ECHOES HAVE BEEN
WEAK TODAY...AND DESPITE SNOW AT SEVERAL METARS IN WEST CENTRAL MN
EARLIER THIS AFTN...CONTINUE TO EXPECT THIS TO BE FLURRY ACTIVITY
WITH NO ACCUMULATION.
TONIGHT...THE LATEST RUC HAS THE BEST HANDLE ON MOISTURE ADVECTION
AND PLACEMENT OF CLOUDS JUST WEST OF THE MISSOURI RIVER IN WRN ND.
WILL CONSIDER THE RUC TIMING OF CLOUDS INTO MY WESTERN ZONES FOR
FCST LOWS...WHICH WILL OCCUR EARLY IN THE EVENING AS CLOUDS
ENCROACH FROM THE WEST. THINK THE NAM IS TOO FAST AND THE GEM HAS
A DECENT HANDLE ON THE COLDEST TEMPS...BUT THE LATTER MAY STILL BE
TOO FAST IN BRINGING CLOUD COVER IN. THUS WILL LEAN TOWARD GEM
SOLUTION BUT CUT TEMPS FURTHER DOWN ALONG WESTERN ZONES AS I
BELIEVE WE WILL HAVE A COUPLE OF HOURS FOR TEMPS TO DROP BEFORE
CLOUDS MOVE IN...GIVEN SNOW ESP IN THE NORTHWEST...AND OVERNIGHT
TEMPS BEGIN TO RISE. COLDEST TEMPS SHOULD BE IN NORTHWEST
MINNESOTA NORTH OF THE PRESENT CLOUDS. COULD SEE TEMPS DOWN INTO
DOUBLE DIGITS...PER GEM GUIDANCE...BUT GENERALLY KEPT TEMPS IN THE
5 TO 10 BELOW RANGE.
LOW PRESSURE WILL THEN MOVE ACROSS THE NORTHERN TIER WITH MODEST
WARM ADVECTION / ISENTROPIC LIFT AFT 03Z. MODELS IN DECENT
AGREEMENT ON PLACEMENT OF SNOWFALL...WITH THE NORTHERN VALLEY
EXPECTED TO RECEIVE THE MOST AS NORTHEASTERN ND EXPECTED TO HAVE
THE STRONGEST ISENTROPIC LIFT. GENERALLY 1 TO 3 INCHES ACROSS THE
NORTH AS THIS SYSTEM MOVES BY. CLOUD ADVECTION WILL CAUSE MOST
SITES TO SEE OVERNIGHT TEMPS BEGIN TO RISE BY 06Z TO 09Z (EARLIER
IN THE WEST). BEST ISENTROPIC LIFT / LOWEST CONDENSATION PRESSURE
DEFICITS GENERALLY NORTH OF THE HWY 2 CORRIDOR SO EXPECT A SHARP
CUTOFF ACROSS SOUTHERN ZONES...BUT SOME FLURRIES ARE POSSIBLE.
WEDNESDAY AND WED NIGHT...MODELS GENERALLY PULL PRECIP OUT OF REGION BY
EARLY AFTERNOON TUESDAY. THUS HAVE REDUCED POPS FOR AFTN HOURS.
NORTHERLY FLOW THEN USHERS IN A COLD CANADIAN AIR MASS. MODELS
ARE PRODUCING PRECIP WEDNESDAY NIGHT AS A JET MAX MOVES ACROSS
SOUTH DAKOTA. WHILE ISENTROPIC SURFACES DO BRING A SWATH OF LOWER
CONDENSATION PRESSURE DEFICITS ACROSS THE AREA...ISENTROPIC LIFT
IS WEAK. HOWEVER DO SEE POTENTIAL FOR MORE STRATUS AND FLURRIES AS
MODELS INDICATE LOW LEVEL MOISTURE MOVING IN AFT 06Z. WILL
CONTINUE FLURRIES FOR WED NIGHT.
THURSDAY... RETURN FLOW WILL SLOWLY BEGIN OVER DEVILS LAKE REGION
ON THU. GFS SHOWS MODEST ISENTROPIC LIFT OVER WESTERN
ZONES...WITH MODERATELY LOW CONDENSATION PRESSURE DEFICITS WHILE
THE NAM IS DRY. WILL CONTINUE SLIGHT CHANCE POPS IN THE
WEST...HOWEVER CONFIDENCE FOR MEASURABLE PRECIP WITH THIS WAVE IS
LOW GIVEN MODEL DIFFERENCES.
FRIDAY...SOUTHEASTERLY FLOW AND INCREASED SOLAR SHOULD ALLOW TEMPS
TO RISE INTO THE UPPER TEENS IN THE NORTH AND LOWER 20S ACROSS THE
SOUTH...WITH FRIDAY BEING THE WARMEST DAY OF THE SHORT TERM.
.LONG TERM... /FRIDAY NIGHT THROUGH TUESDAY/
PSEUDO SPLIT FLOW THROUGH THE PERIOD WITH THE MAIN STORM TRACK SOUTH
OF FA THIS WEEKEND. FARTHER NORTH SOLUTIONS OF GEM/ECMWF HAVE FAR
SE/E FA ON NORTHERN FRINGE OF SNOW SHIELD SO WILL MAINTAIN LOW POPS
THIS AREA. TEMPERATURES LOOK SEASONAL WITH NO REAL COLD AIR
INTRUSION THROUGH THE PERIOD.
&&
.AVIATION...
CLEARING CONTINUES TO SPREAD FROM NW-SE WITH MOST OF FA VFR BY LATE
AFTERNOON. VFR CIGS WILL SPREAD IN LATER TONIGHT WITH -SN DEVELOPING
ACROSS FAR NORTH LATE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
SPEICHER/VOELKER
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1028 AM CST TUE DEC 11 2012
.DISCUSSION...
MORNING UPDATE WILL ADDRESS SKY TRENDS AND TEMPS. CURRENT VIS
SATELLITE SHOWING SOME CLEARING OVER NORTH CENTRAL AND NORTHEAST
NORTH DAKOTA WITH MORE CLOUD COVER ENCROACHING INTO THE FAR
WESTERN PART OF THE STATE. WILL REDUCE SKY SOMEWHAT BUT EXPECT
THIS TO BE 4 TO 6 HOURS OF PARTLY CLOUD BEFORE CLOUDS MOVE BACK IN
EARLY EVENING. COLDEST TEMPS SO FAR THIS MORNING IN THE FOOTHILLS
OF THE TURTLE MTS. WHILE RUC IS TOO COLD...IT IS DOING REASONABLY
WELL ON HIGHLIGHTING COLD SPOTS THIS MORNING SO WILL USE ITS TEMPS
FOR GUIDANCE...WARMING THINGS UP A DEG OR TWO AS NECESSARY.
CURRENT SN AT GFK IS VERY FINE FLURRIES...THUS NO PLAN TO UPDATE
TO MEASURABLE SNOWFALL THIS MORNING. VERY LITTLE ON RADAR...SO
FLURRIES LOOK GOOD.
&&
.AVIATION...
PATCHY STRATUS CONTINUES TO COVER THE SOUTHERN VALLEY AND WEST
CENTRAL MINNESOTA. MUCH OF NORTH CENTRAL NORTH DAKOTA APPEARS
CLEAR ON SATELLITE HOWEVER MORE CLOUD COVER TO THE WEST WILL MOVE
IN BY EVENING. EXPECT TO SEE IN AND OUT CLOUDS FROM THE VALLEY
WEST TODAY. STRATUS OVER MINNESOTA IS VERY THIN...WITH LAND
FEATURES APPEARING ON VIS SAT...BUT NONETHELESS MVFR CIGS FOR THE
COMING HOURS. ANY FLURRIES CREATING RESTRICTIONS TO VIS WILL NOT
BE WIDESPREAD ENOUGH TO INCLUDE IN THE TAFS AT THIS POINT.
CEILINGS COULD LIFT A BIT BY AFTERNOON...BUT REMAIN ON THE LOWER
END OF VFR. LIGHT AND VARIABLE WINDS WILL PICK UP FROM THE SOUTH
AFTER 00Z AT 10 KTS OR SO.
&&
.PREV DISCUSSION... /ISSUED 345 AM CST TUE DEC 11 2012/
SHORT TERM...
CHANCES FOR SNOW AND TEMPERATURES WILL BE THE PRIMARY FORECAST
ISSUE FOR THE PERIOD.
NORTHWESTERLY FLOW ALOFT WILL CONTINUE TODAY WITH WEAK HIGH
PRESSURE OVER THE REGION. MODELS SHOW QUITE A BIT OF LOW LEVEL
MOISTURE UNDER THE SFC HIGH...WHICH FITS WITH THE AREAS OF STRATUS
SEEN ON SAT LOOP OVER ND AND SOUTHERN CANADA. THERE HAVE ALSO BEEN
SEVERAL LOCATIONS UNDER THE STRATUS REPORTING FLURRIES. THINK THAT
THIS TREND WILL CONTINUE INTO THE MORNING HOURS SO BUMPED UP CLOUD
COVER AND INCLUDED A FLURRY MENTION. THERE WILL BE SOME DECENT
COLD AIR ADVECTION ON THE BACKSIDE OF THE DEPARTING SFC
TROUGH...MOSTLY OVER THE NORTHEASTERN CWA. WITH CLOUDS AND SNOW
COVER KEPT HIGHS MOSTLY IN THE SINGLE DIGITS WITH SOME AREAS
SEEING NON-DIURNAL TEMPERATURES.
TONIGHT...THE UPPER FLOW BECOMES MORE SPLIT WITH A NORTHERN BRANCH
WEAK SHORTWAVE MOVING THROUGH SOUTHERN CANADA. THIS SHOULD HELP
STRENGTHEN THE SFC LOW OVER THE WESTERN PLAINS...WITH STRONG WARM
AIR ADVECTION OVER MOST OF THE CWA. THINK THAT MANY AREAS WILL SEE
STEADY OR RISING TEMPS OVERNIGHT. THERE SHOULD BE SOME GOOD
ISENTROPIC LIFT OVER THE NORTHERN CWA TONIGHT...WITH THE BEST
CONDENSATION PRESSURE DEFICITS ENTERING THE DEVILS LAKE BASIN
SOMETIME AROUND MIDNIGHT. MODELS COMING INTO TO BETTER AGREEMENT
ON THE QPF OVER THE NORTHERN CWA...ALTHOUGH THERE ARE STILL SOME
DIFFERENCES IN EXACT TIMING AND IF THE HIGHEST AMOUNTS WILL BE
NORTH OR SOUTH OF THE CANADIAN BORDER. BUMPED UP POPS FOR THE
NORTHERN CWA...MAINLY DURING THE LATE TONIGHT/TOMORROW MORNING
TIME FRAME. A COUPLE OF INCHES OF ACCUMULATION ALONG THE CANADIAN
BORDER CONTINUES TO SEEM MOST LIKELY AT THIS POINT.
THE UPPER SHORTWAVE CONTINUES TO MOVE THROUGH SOUTHERN
CANADA WEDNESDAY...WITH ANOTHER WEAK SHORTWAVE COMING IN QUICKLY
FROM THE WEST. KEPT POPS GOING IN THE NORTHERN CWA THROUGHOUT THE
DAY ON WEDNESDAY. THE GFS TRIES TO BRING COLD AIR DOWN A BIT
FASTER THAN THE NAM AND ECMWF...WHICH KEEP THE CWA IN THE WARM AIR
FOR MUCH OF THE DAY. AS THE GFS SEEMS TO BE AN OUTLIER WILL LEAN
TOWARDS KEEPING WEDNESDAY AS THE WARMEST DAY...BUT WILL HAVE TO
KEEP AN EYE ON TH SITUATION.
THE COLD AIR MOVES IN WEDNESDAY NIGHT...WITH A FAIR AMOUNT OF LOW
LEVEL MOISTURE...SO THINK ANOTHER NIGHT OF STRATUS AND FLURRIES IS
POSSIBLE SO KEPT THE MENTION WE HAD GOING. ANOTHER WEAK SHORTWAVE
WILL MOVE THROUGH SOUTHERN CANADA THURSDAY INTO THURSDAY
NIGHT...SO KEPT SOME LOW POPS GOING FOR THE FAR NORTH ALTHOUGH THE
BEST CHANCES FOR ANYTHING SIGNIFICANT WILL BE IN MANITOBA. WITH
MORE COLD AIR MOVING IN HIGHS THURSDAY WILL BE KNOCKED BACK DOWN
INTO THE TEENS WITH LOWS MAINLY IN THE SINGLE DIGITS.
LONG TERM (FRIDAY-MONDAY)...
FAIRLY TRANQUIL WEATHER IS EXPECTED THROUGHOUT THIS PERIOD. FORECAST
CONFIDENCE QUICKLY DECREASES THOUGH FOR SUNDAY/MONDAY WITH COMPLEX
SPLIT FLOW PATTERN ACROSS THE NATION. INITIALLY...00Z MODELS ARE IN
GOOD AGREEMENT FOR FRIDAY SHOWING WEAK RETURN FLOW/WARM AIR
ADVECTION...WITH TEMPS MODERATING CLOSER TO NORMAL. ON SATURDAY...A
SOUTHERN STREAM DISTURBANCE IS EXPECTED TO LIFT NORTHEAST...WITH THE
SFC LOW TRACKING FROM THE CENTRAL PLAINS TO THE WESTERN GREAT LAKES
BY EARLY SUNDAY. THIS TRACK WOULD KEEP MUCH OF THE PRECIP FROM THIS
SYSTEM SOUTH AND EAST OF THE REGION...AND KEPT DRY FORECAST INTACT.
WENT WITH A DRY FORECAST BEYOND SATURDAY...ALTHOUGH SIGNIFICANT MODEL
SPREAD LEADS TO VERY LOW FORECAST CONFIDENCE. MODELS INDICATE A
PRONOUNCED SPLIT FLOW PATTERN CONTINUING WITH AN ENHANCED SOUTHERN
STREAM. MODELS DIFFER QUITE A BIT ON THE TIMING AND SUBSEQUENT
AMPLIFICATION/EVOLUTION OF SHORTWAVE TROUGHS...ALTHOUGH BOTH THE 00Z
GFS/ECMWF DO SHOW ANOTHER SIGNIFICANT SHORTWAVE TROUGH DIVING INTO
THE SOUTHERN PLAINS BY LATE IN THE PERIOD. WITH RELATIVELY ZONAL
FLOW ALOFT...NO SIGNIFICANT COLD AIR INTRUSIONS WOULD BE EXPECTED
THROUGH THE END OF THE PERIOD...WITH TEMPS NEAR NORMAL OR EVEN
SLIGHTLY ABOVE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
SPEICHER
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
437 AM EST TUE DEC 11 2012
.SYNOPSIS...
A LARGE HIGH PRESSURE AREA WILL SETTLE OVER THE REGION FOR THE
REST OF THE WEEK. EXPECT DRY WEATHER WITH SEASONABLY COOL
TEMPERATURES AT FIRST...BUT A GRADUAL WARMING WILL OCCUR LATER IN
THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LIGHT SNOW OR RAIN SHOWERS OCCURRING OVER PORTIONS OF THE LAUREL
HIGHLANDS AND NORTHWEST MOUNTAINS. CLOUD LAYER NOT ALL THAT
COLD...AND RATHER SHALLOW. THUS...WHERE TEMPS ARE AT OR BELOW
FREEZING...THERE COULD BE A FEW PATCHES OF FREEZING DRIZZLE. BUT
THE AIR WILL ACTUALLY GET COLDER THROUGH THE MORNING. MANY
LOCATIONS WILL HAVE TO WAIT UNTIL LATE MORNING OF EARLY AFTERNOON
TO SEE THE THERMOMETER RISE...AND THEN ONLY SLIGHTLY. THERE COULD
STILL BE A COATING OF SNOW ON THE HIGHER RIDGES AS SCT SHSN KEEP
GOING FOR MUCH OF THE MORNING. WILL CUT OFF ALL POPS AFTER
THAT...AS ANYTHING WILL BE FLURRIES AFTER THAT. 8H TEMPS LEVEL OFF
AND THEN BEGIN TO RISE LATE TODAY AND THE INVERSION LOWERS
SIGNIFICANTLY BY THE END OF THE DAY. THIS SHOULD SPELL THE END OF
THE STRATO CU. BUT WILL LINGER BKN SKY COVER MOST OF THE DAY IN
THE WEST AND INTO THE EARLY EVENING FOR THE NRN MTS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
HIGH PRESSURE TAKES OVER TONIGHT AND THE RIDGE SETTLES IN FOR THE
LONG HAUL. BEGINNING A PROLONGED PERIOD OF RATHER BRIGHT AND FAIR
WEATHER. HIGHS IN THE 30S AND 40S WILL AVERAGE A FEW DEG EITHER
SIDE OF NORMAL.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
ALL MODEL GUIDANCE SHOWS A LARGE AREA OF HIGH PRESSURE DOMINATING
THE REGIONAL WEATHER PATTERN THROUGH FRIDAY...SUPPORTING A HIGH
CONFIDENCE FCST OF FAIR WEATHER AND LGT WINDS. WITH THE BENEFIT OF
MSUNNY SKIES...DAYTIME HIGHS SHOULD REMAIN NEAR TO SLIGHTLY ABOVE
NORMAL. HOWEVER...OVERNIGHT LOWS SHOULD BE NEAR DECEMBER NORMS DUE
TO THE CLEAR SKIES/CALM WIND.
LOW PRESSURE WILL EJECT NEWD FROM THE S/CNTRL PLAINS THEN AFFECT
THE CNTRL-ERN STATES INTO THE WEEKEND. SOME WINTRY PCPN IS PSBL ON
THE NRN SIDE OF THE MSTR SHIELD ASSOC WITH THIS SYSTEM. THERE IS
STILL A HIGH LEVEL OF UNCERTAINTY IN STORM TRACK AND EXACT
LOCATION OF THE RAIN/SNOW LINE...BUT CURRENTLY EXPECT ANY WINTRY
WEATHER TO BE CONFINED TO SOME PORTION OF AN AREA COVERING THE
GRTLKS INTO THE NORTHEAST STATES. STAY TUNED FOR MORE DETAILS ON
POTENTIAL FOR WINTRY WEATHER THIS WEEKEND.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
COLD FRONT HAS PUSHED SOUTHEAST OF THE ENTIRE REGION AS OF 09Z.
HOWEVER...A WEAK WAVE OF LOW PRES ALONG FRONT IS PRODUCING
LINGERING SHRA ACROSS SOUTHEAST PA. RADAR TRENDS SUGGEST THE SHRA
WILL MOVE EAST OF MDT/LNS BY ARND 11Z.
NW WINDS WILL CONTINUE TO FORCE RESIDUAL LOW LVL MOISTURE OVR THE
ALLEGHENY MTNS...LIKELY RESULTING IN IFR CIGS AND OCNL -SHSN AT
BFD AND JST THRU ARND DAWN. MDL SOUNDINGS INDICATE SHALLOW CLOUD
HGTS COULD EVEN YIELD A BIT OF -FZDA POSSIBLE AT JST EARLY THIS
AM. LATEST RAP MDL OUTPUT SUPPORTS THE IDEA OF GRADUALLY IMPROVING
CIGS/VSBYS AT BFD AND JST BY ARND 12Z...AS DRIER AIR WORKS IN FROM
THE WEST.
EAST OF THE MTNS...DRYING/DOWNSLOPING NW FLOW SHOULD YIELD MAINLY
VFR CONDS AT IPT/MDT/LNS THIS MORNING. HOWEVER...MDL SOUNDINGS
AND CLIMATOLOGY WOULD SUGGEST AOO AND UNV COULD SEE OCNL MVFR
STRATOCU EARLY THIS AM.
HIGH PRESSURE WILL BUILD INTO THE REGION BY TUE AFTN...LIKELY
CAUSING ANY LINGERING MVFR STRATOCU TO BREAK UP OVR THE W MTNS.
HIGH PRES DIRECTLY OVR THE REGION TUE NIGHT SHOULD ENSURE VFR
CONDS AND A NEARLY CALM WIND.
OUTLOOK...
WED-FRI...NO SIG WX EXPECTED.
SAT...RAIN/FZRA POSSIBLE LATE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO
SHORT TERM...DANGELO/RXR
LONG TERM...STEINBUGL
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
420 AM EST TUE DEC 11 2012
.SYNOPSIS...
A LARGE HIGH PRESSURE AREA WILL SETTLE OVER THE REGION FOR THE
REST OF THE WEEK. EXPECT DRY WEATHER WITH SEASONABLY COOL
TEMPERATURES AT FIRST...BUT A GRADUAL WARMING WILL OCCUR LATER IN
THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LIGHT SNOW SHOWERS OCCURRING OVER PORTIONS OF THE LAUREL
HIGHLANDS AND NORTHWEST MOUNTAINS. BUT THE SFC TEMPS STILL TOO
WARM FOR ACCUM IN MOST PLACES...AS THEY ARE JUST GETTING DOWN TO
FREEZING NOW. STILL EXPECT A COATING OF SNOW ON THE HIGHER
RIDGES AS SCT SHSN KEEP GOING INTO MID MORNING. WILL CUT OFF ALL
POPS AFTER THAT...AS ANYTHING WILL BE FLURRIES AFTER THAT. 8H
TEMPS BEGIN TO RISE LATER TODAY AND THIS SHOULD SPELL THE END OF
THE STRATO CU. BUT WILL LINGER BKN SKY COVER INTO THE EARLY
EVENING FOR THE NRN MTS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
HIGH PRESSURE TAKES OVER TONIGHT AND THE RIDGE SETTLES IN FOR THE
LONG HAUL. BEGINNING A PROLONGED PERIOD OF RATHER BRIGHT AND FAIR
WEATHER. HIGHS IN THE 30S AND 40S WILL AVERAGE A FEW DEG EITHER
SIDE OF NORMAL.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
ALL MODEL GUIDANCE SHOWS A LARGE AREA OF HIGH PRESSURE DOMINATING
THE REGIONAL WEATHER PATTERN THROUGH FRIDAY...SUPPORTING A HIGH
CONFIDENCE FCST OF FAIR WEATHER AND LGT WINDS. WITH THE BENEFIT OF
MSUNNY SKIES...DAYTIME HIGHS SHOULD REMAIN NEAR TO SLIGHTLY ABOVE
NORMAL. HOWEVER...OVERNIGHT LOWS SHOULD BE NEAR DECEMBER NORMS DUE
TO THE CLEAR SKIES/CALM WIND.
LOW PRESSURE WILL EJECT NEWD FROM THE S/CNTRL PLAINS THEN AFFECT
THE CNTRL-ERN STATES INTO THE WEEKEND. SOME WINTRY PCPN IS PSBL ON
THE NRN SIDE OF THE MSTR SHIELD ASSOC WITH THIS SYSTEM. THERE IS
STILL A HIGH LEVEL OF UNCERTAINTY IN STORM TRACK AND EXACT
LOCATION OF THE RAIN/SNOW LINE...BUT CURRENTLY EXPECT ANY WINTRY
WEATHER TO BE CONFINED TO SOME PORTION OF AN AREA COVERING THE
GRTLKS INTO THE NORTHEAST STATES. STAY TUNED FOR MORE DETAILS ON
POTENTIAL FOR WINTRY WEATHER THIS WEEKEND.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
COLD FRONT HAS PUSHED SOUTHEAST OF THE ENTIRE REGION AS OF 09Z.
HOWEVER...A WEAK WAVE OF LOW PRES ALONG FRONT IS PRODUCING
LINGERING SHRA ACROSS SOUTHEAST PA. RADAR TRENDS SUGGEST THE SHRA
WILL MOVE EAST OF MDT/LNS BY ARND 11Z.
NW WINDS WILL CONTINUE TO FORCE RESIDUAL LOW LVL MOISTURE OVR THE
ALLEGHENY MTNS...LIKELY RESULTING IN IFR CIGS AND OCNL -SHSN AT
BFD AND JST THRU ARND DAWN. MDL SOUNDINGS INDICATE SHALLOW CLOUD HGTS
COULD EVEN YIELD A BIT OF -FZDA POSSIBLE AT JST EARLY THIS AM.
LATEST RAP MDL OUTPUT SUPPORTS THE IDEA OF GRADUALLY IMPROVING
CIGS/VSBYS AT BFD AND JST BY ARND 12Z...AS DRIER AIR WORKS IN FROM
THE WEST.
EAST OF THE MTNS...DRYING/DOWNSLOPING NW FLOW SHOULD YIELD MAINLY
VFR CONDS AT IPT/MDT/LNS THIS MORNING. HOWEVER...MDL SOUNDINGS AND CLIMATOLOGY
WOULD SUGGEST AOO AND UNV COULD SEE OCNL MVFR STRATOCU EARLY THIS
AM.
HIGH PRESSURE WILL BUILD INTO THE REGION BY TUE AFTN...LIKELY
CAUSING ANY LINGERING MVFR STRATOCU TO BREAK UP OVR THE W MTNS.
HIGH PRES DIRECTLY OVR THE REGION TUE NIGHT SHOULD ENSURE VFR
CONDS AND A NEARLY CALM WIND.
OUTLOOK...
WED-FRI...NO SIG WX EXPECTED.
SAT...RAIN/FZRA POSSIBLE LATE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO
SHORT TERM...DANGELO/RXR
LONG TERM...STEINBUGL
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
135 AM EST TUE DEC 11 2012
.SYNOPSIS...
A LARGE HIGH PRESSURE AREA WILL SETTLE OVER THE REGION FOR THE
REST OF THE WEEK. EXPECT DRY WEATHER WITH SEASONABLY COOL
TEMPERATURES AT FIRST...BUT A GRADUAL WARMING WILL OCCUR LATER IN
THE WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
LIGHT SNOW SHOWERS OCCURRING OVER PORTIONS OF THE LAUREL
HIGHLANDS AND NORTHWEST MOUNTAINS. BUT THE SFC TEMPS STILL TOO
WARM FOR ACCUM IN MOST PLACES...AS THEY ARE JUST GETTING DOWN TO
FREEZING NOW. STILL EXPECT A COATING OF SNOW ON THE HIGHER
RIDGES AS SCT SHSN KEEP GOING INTO MID MORNING. WILL CUT OFF ALL
POPS AFTER THAT...AS ANYTHING WILL BE FLURRIES AFTER THAT. 8H
TEMPS BEGIN TO RISE LATER TODAY AND THIS SHOULD SPELL THE END OF
THE STRATO CU. BUT WILL LINGER BKN SKY COVER INTO THE EARLY
EVENING FOR THE NRN MTS.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM WEDNESDAY/...
HIGH PRESSURE TAKES OVER TONIGHT AND THE RIDGE SETTLES IN FOR THE
LONG HAUL. BEGINNING A PROLONGED PERIOD OF RATHER BRIGHT AND FAIR
WEATHER. HIGHS IN THE 30S AND 40S WILL AVERAGE A FEW DEG EITHER
SIDE OF NORMAL.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
ALL MODEL GUIDANCE SHOWS A LARGE AREA OF HIGH PRESSURE DOMINATING
THE REGIONAL WEATHER PATTERN THROUGH FRIDAY...SUPPORTING A HIGH
CONFIDENCE FCST OF FAIR WEATHER AND LGT WINDS. WITH THE BENEFIT OF
MSUNNY SKIES...DAYTIME HIGHS SHOULD REMAIN NEAR TO SLIGHTLY ABOVE
NORMAL. HOWEVER...OVERNIGHT LOWS SHOULD BE NEAR DECEMBER NORMS DUE
TO THE CLEAR SKIES/CALM WIND.
LOW PRESSURE WILL EJECT NEWD FROM THE S/CNTRL PLAINS THEN AFFECT
THE CNTRL-ERN STATES INTO THE WEEKEND. SOME WINTRY PCPN IS PSBL ON
THE NRN SIDE OF THE MSTR SHIELD ASSOC WITH THIS SYSTEM. THERE IS
STILL A HIGH LEVEL OF UNCERTAINTY IN STORM TRACK AND EXACT
LOCATION OF THE RAIN/SNOW LINE...BUT CURRENTLY EXPECT ANY WINTRY
WEATHER TO BE CONFINED TO SOME PORTION OF AN AREA COVERING THE
GRTLKS INTO THE NORTHEAST STATES. STAY TUNED FOR MORE DETAILS ON
POTENTIAL FOR WINTRY WEATHER THIS WEEKEND.
&&
.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
COLD FRONT HAS PUSHED SOUTHEAST OF THE ENTIRE REGION AT 06Z. UPPER
LVL TROF LIFTING THRU CENTRAL PA...PRODUCING LAST BATCH OF STEADY
RAIN ACROSS EASTERN PA AT 0530Z. BEHIND THIS FEATURE NW WINDS
WILL CONTINUE TO FORCE RESIDUAL LOW LVL MOISTURE OVR THE ALLEGHENY
MTNS...LIKELY RESULTING IN IFR CIGS AND OCNL -SHSN AT JST THRU
ARND 12Z. LATEST RAP MDL OUTPUT SUPPORTS THIS IDEA OF PERSISTENT
IFR CONDS AT JST THRU DAWN. AT BFD...ARRIVAL OF DRIER AIR AND
LESS SIGNIFICANT OROGRAPHIC FORCING SHOULD YIELD MAINLY MVFR
STRATOCU THIS MORNING.
EAST OF THE MTNS...DRYING/DOWNSLOPING NW FLOW SHOULD YIELD MAINLY
VFR CONDS AFTER 06Z. HOWEVER...CLIMATOLOGY WOULD SUGGEST AOO AND
UNV COULD SEE OCNL MVFR STRATOCU EARLY THIS AM.
HIGH PRESSURE WILL BUILD INTO THE REGION BY TUE AFTN...LIKELY
CAUSING ANY LINGERING MVFR STRATOCU TO BREAK UP OVR THE W MTNS.
HIGH PRES DIRECTLY OVR THE REGION TUE NIGHT SHOULD ENSURE VFR
CONDS AND A NEARLY CALM WIND.
OUTLOOK...
WED-FRI...NO SIG WX EXPECTED.
SAT...RAIN/FZRA POSSIBLE LATE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO
SHORT TERM...DANGELO/RXR
LONG TERM...STEINBUGL
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1241 AM EST TUE DEC 11 2012
.SYNOPSIS...
COLDER AIR WILL SWEEP INTO THE REGION TONIGHT BEHIND A COLD FRONT.
RECENT WET WEATHER WILL GIVE WAY TO COLDER AND DRIER CONDITIONS
FOR TUESDAY AND THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
SFC COLD FRONT IN NOW EXITING LANCASTER COUNTY. RAIN SHOWERS HAVE
CHANGED TO SNOW SHOWERS OVER PORTIONS OF THE LAUREL HIGHLANDS...
WEST CENTRAL MOUNTAINS AND NORTHWEST MOUNTAINS. WITH FROPA...TEMPS
IN THE LOWER 50S HAVEN FALLEN BACK THROUGH THE 40S AND INTO THE
MID TO UPPER 30S OVER THE WEST AND NORTH. DESPITE MARGINAL TEMPS...
STILL EXPECT A COATING OF SNOW ON THE HIGHER RIDGES. ELSEWHERE..NO
ACCUMS ARE EXPECTED.
COLDER AIR CONTINUES TO WORK IN OVERNIGHT...TAKING A GOOD PORTION OF
THE OVERNIGHT TO REACH THE LOWER SUSQ. AIR STILL NOT FORMIDABLE
FOR DECEMBER THOUGH...AS THESE READINGS REMAIN WELL ABOVE NORMAL
FOR THIS TIME OF YEAR. HIGH PRESSURE BEGINS TO BUILD IN LATE
TONIGHT INTO TUE AS CONDITIONS IMPROVE BACK TO VFR BY TUES MORNING
FOR MOST...POSS TUE AFT IN THE HIGHER TERRAIN.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
HIGH PRESSURE NOSES IN PRETTY QUICKLY TUESDAY SHUTTING DOWN
WHATEVER SNOW SHOWERS THAT ARE ONGOING IN THE WEST...AND BEGINNING
A PROLONGED PERIOD OF RATHER BRIGHT AND FAIR WEATHER.
HIGHS IN THE 30S AND 40S WILL AVERAGE A FEW DEG EITHER SIDE OF
NORMAL.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
ALL MODEL GUIDANCE SHOWS A LARGE AREA OF HIGH PRESSURE DOMINATING
THE REGIONAL WEATHER PATTERN THROUGH FRIDAY...SUPPORTING A HIGH
CONFIDENCE FCST OF FAIR WEATHER AND LGT WINDS. WITH THE BENEFIT OF
MSUNNY SKIES...DAYTIME HIGHS SHOULD REMAIN NEAR TO SLIGHTLY ABOVE
NORMAL. HOWEVER...OVERNIGHT LOWS SHOULD BE NEAR DECEMBER NORMS DUE
TO THE CLEAR SKIES/CALM WIND.
LOW PRESSURE WILL EJECT NEWD FROM THE S/CNTRL PLAINS THEN AFFECT
THE CNTRL-ERN STATES INTO THE WEEKEND. SOME WINTRY PCPN IS PSBL ON
THE NRN SIDE OF THE MSTR SHIELD ASSOC WITH THIS SYSTEM. THERE IS
STILL A HIGH LEVEL OF UNCERTAINTY IN STORM TRACK AND EXACT
LOCATION OF THE RAIN/SNOW LINE...BUT CURRENTLY EXPECT ANY WINTRY
WEATHER TO BE CONFINED TO SOME PORTION OF AN AREA COVERING THE
GRTLKS INTO THE NORTHEAST STATES. STAY TUNED FOR MORE DETAILS ON
POTENTIAL FOR WINTRY WEATHER THIS WEEKEND.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
COLD FRONT HAS PUSHED SOUTHEAST OF THE ENTIRE REGION AT 06Z. UPPER
LVL TROF LIFTING THRU CENTRAL PA...PRODUCING LAST BATCH OF STEADY
RAIN ACROSS EASTERN PA AT 0530Z. BEHIND THIS FEATURE NW WINDS
WILL CONTINUE TO FORCE RESIDUAL LOW LVL MOISTURE OVR THE ALLEGHENY
MTNS...LIKELY RESULTING IN IFR CIGS AND OCNL -SHSN AT JST THRU
ARND 12Z. LATEST RAP MDL OUTPUT SUPPORTS THIS IDEA OF PERSISTENT
IFR CONDS AT JST THRU DAWN. AT BFD...ARRIVAL OF DRIER AIR AND
LESS SIGNIFICANT OROGRAPHIC FORCING SHOULD YIELD MAINLY MVFR
STRATOCU THIS MORNING.
EAST OF THE MTNS...DRYING/DOWNSLOPING NW FLOW SHOULD YIELD MAINLY
VFR CONDS AFTER 06Z. HOWEVER...CLIMATOLOGY WOULD SUGGEST AOO AND
UNV COULD SEE OCNL MVFR STRATOCU EARLY THIS AM.
HIGH PRESSURE WILL BUILD INTO THE REGION BY TUE AFTN...LIKELY
CAUSING ANY LINGERING MVFR STRATOCU TO BREAK UP OVR THE W MTNS.
HIGH PRES DIRECTLY OVR THE REGION TUE NIGHT SHOULD ENSURE VFR
CONDS AND A NEARLY CALM WIND.
OUTLOOK...
WED-FRI...NO SIG WX EXPECTED.
SAT...RAIN/FZRA POSSIBLE LATE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE/RXR
NEAR TERM...DEVOIR/RXR
SHORT TERM...RXR
LONG TERM...STEINBUGL
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
937 PM EST WED DEC 12 2012
.SYNOPSIS...
HIGH PRESSURE WILL PERSIST OVER THE AREA INTO SATURDAY. A FRONTAL
SYSTEM WILL THEN APPROACH THE NORTH CAROLINA MOUNTAINS EARLY SUNDAY
AND CROSS EAST OF THE FORECAST AREA BY EARLY MONDAY. ANOTHER FRONTAL
SYSTEM WILL APPROACH THE REGION ON TUESDAY.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 935 PM...AREAS OF LIGHT RAIN WITH A FEW EMBEDDED HEAVIER SHRA
CONTINUE TO MOVE ACROSS MAINLY THE SRN PORTION OF THE CWFA ALONG AND
SOUTH OF I-85. THIS IS THE RAIN MOVING IN WITH THE PREVIOUSLY
MENTIONED SHORT WAVE AND JET MAX. STILL EXPECT THIS RAIN TO ONLY
SLOWLY MOVE ACROSS THEN EAST OF THE AREA THRU THE NITE. DO EXPECT
THE RAIN TO BE EAST OF THE AREA BY DAYBREAK HOWEVER. THE 00Z FFC
RAOB SHOWED AN AREA OF ELEVATED INSTABILITY...CAPE AROUND 200
J/KG...WITH PARCELS LIFTED FROM NEAR H7. IN FACT...THE HEAVIER SHRA
HAVE INCREASED IN THE PAST HOUR AND COULD CROSS THE FAR SRN CWFA
THRU THE EVENING. NO CG LIGHTNING STRIKES SHOWING UP...BUT
EXPERIMENTAL IN CLOUD LIGHTNING PRODUCT NOW SHOWING A STRIKE MOVING
JUST SOUTH OF ABBEVILLE AND GREENWOOD COUNTY. CANNOT RULE OUT A
BRIEF RUMBLE OF THUNDER...OR SOME SMALL HAIL AND GUSTY WINDS. TEMPS
ARE CURRENTLY RUNNING A LITTLE WARMER THAN FCST. HOWEVER...STILL
EXPECT LOWS TO COOL TO THE PREV UPDATED MINS.
AS OF 650 PM... AREAS OF LIGHT RAIN WILL MOVE BACK INTO THE AREA
THIS EVENING AHEAD OF A SHORT WAVE AND DEVELOPING UPPER DIVERGENCE
ASSOCIATED WITH THE RIGHT ENTRANCE REGION OF THE POLAR JET. EVEN
WITH A STRONG COLD POOL MOVING ACROSS OR NEAR THE AREA...EXPECT ANY
HEAVIER SHRA TO REMAIN SOUTH OF THE CWFA. THAT SAID...CANNOT RULE
OUT A HEAVIER SHRA OVER THE SRN CWFA WITH SOME VERY SMALL HAIL OR
GRAUPEL. ANY OF THESE WOULD BE SHORT LIVED. 18Z GUIDANCE KEEPS THE
PRECIP AND LOW CLOUDS IN A LITTLE LONGER THAN PREV GUIDANCE. HAVE
FOLLOWED THESE TRENDS WITH THE FCST GIVEN THE POSITION AND MOVEMENT
OF UPSTREAM PRECIP. MADE SOME MINOR ADJUSTMENTS TO OVERNIGHT LOWS IN
LINE WITH THIS GUIDANCE AS WELL. LOW END GUSTY WINDS WILL DEVELOP
FROM TIME TO TIME TONIGHT AND EARLY THU MORN.
PREVIOUS DISCUSSION...STRONG UPPER DIVERGENCE IN THE ENTRANCE REGION
OF A 130 KT POLAR JET HAS RESULTED IN LIGHT RAIN OVER PARTS OF THE
UPSTATE AND THE SRN NC PIEDMONT. THE LATEST RUC SHOWS THE DIVERGENCE
WEAKENING FOR A FEW HOURS THIS AFTERNOON...THEN INCREASING OVER THE
SRN HALF OF THE FORECAST AREA AGAIN EARLY THIS EVENING AS A SHORT
WAVE CURRENTLY OVER MISSISSIPPI EJECTS QUICKLY TO THE NE. THE GFS
ALSO HAS AN IMPRESSIVE QPF MAX OVER THE SRN PART OF THE UPSTATE AND
CHARLOTTE METRO AREA FROM 00-06 UTC THIS EVENING. WHILE IT/S
0.25-0.50 INCH RAINFALL AMOUNTS ARE ALMOST CERTAINLY TOO
HIGH...LIGHT RAIN SHOULD FILL BACK IN THIS EVENING ACROSS THE SAME
AREAS THAT HAVE BEEN SEEING IT THIS AFTERNOON. THIS WILL BASICALLY
BE AREAS ALONG AND SOUTH OF I-85. IT STILL APPEARS THAT THE RAIN
WILL END BEFORE TEMPERATURES FALL BELOW FREEZING TONIGHT AND I/M NOT
ANTICIPATING ANY P-TYPE PROBLEMS OVERNIGHT. EVEN DURING THE DAYLIGHT
HOURS TODAY THE PCPN SHOULD BE ALL RAIN. WHILE THE DUAL-POL
HYDROMETEOR CLASSIFICATION ALGORITHM IS SHOWING SOME MIXED PCPN OVER
THE CHARLOTTE METRO AREA...THIS IS UP AT 7KFT AND IS NOT REFLECTIVE
OF WHAT IS FALLING AT THE SFC. LAPS SOUNDINGS OVER THIS AREA SHOW
AIR TEMPS WELL ABOVE FREEZING IN THE LOWEST SEVERAL THOUSAND FEET OF
THE ATMOSPHERE.
CLOUDS WILL CLEAR OUT OF THE EASTERN ZONES EARLY TOMORROW AND WE
SHOULD SEE CLEAR BLUE SKIES AND SLIGHTLY BELOW NORMAL TEMPERATURES
FOR THURSDAY.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 2 PM WEDNESDAY...SHORT RANGE MODELS INDICATE THAT THE
FORECAST AREA WILL REMAIN WITHIN THE CENTER OF 1025 MB SFC HIGH AND
UNDER DEEP RIDGING ALOFT. FORECAST SOUNDINGS INDICATE THAT WIDE
DEWPOINT DEPRESSIONS WILL EXIST FROM THE SFC TO THE
TROPOPAUSE...SUPPORTING A 0 PERCENT SKY COVER FORECAST FRIDAY
MORNING. HOWEVER...CIRRUS LEVEL MOISTURE WILL BEGIN TO INCREASE
DURING THE AFTERNOON...LIKELY SUPPORTING A FEW CONTRAILS OR THIN
CIRRUS. CALM WINDS...CLEAR SKY...AND DEEP DRY AIR WILL PROVIDE GOOD
RADIATIONAL COOLING CONDITIONS FRIDAY MORNING. USING A BLEND OF MOS
GUIDANCE...MIN TEMPERATURES SHOULD RANGE FROM THE MID 20S ACROSS THE
MTN VALLEYS TO THE L30S EAST. UNDER SUNNY TO MOSTLY SUNNY
CONDITIONS...HIGH TEMPERATURES ARE FORECAST TO RANGE FROM THE U50S
ACROSS THE MTNS TO THE L60S EAST.
FRIDAY NIGHT...CIRRUS CLOUD COVER WILL INCREASE THROUGH THE
NIGHT...POSSIBLY BECOMING GREATER THAN 5KFT THICK BY 12Z SAT. SFC
CONDITIONS WILL LIKELY REMAIN DRY WITH LIGHT AND VARIABLE TO CALM
WINDS. HOWEVER...THE INCREASING SKY COVER WILL FAVOR MIN
TEMPERATURES AROUND 5 DEGREES WARMER THAN EXPECTED FRIDAY MORNING.
ON SATURDAY...A COLD FRONT WILL APPROACH FROM THE WEST...LIKELY
REMAINING WEST OF THE APPALACHIAN THROUGH 0Z SUNDAY. HOWEVER...LIGHT
RETURN FLOW WILL DEVELOP ACROSS THE FORECAST AREA...RESULTING IN
WEAK WAA. FORECAST SOUNDINGS INDICATE THAT CLOUD BASES WILL LOWER TO
AROUND 10 KFT BY THE LATE AFTERNOON...REMAINING RATHER THICK ALOFT.
CLOUD COVER IS FORECAST TO BECOME MOSTLY CLOUDY BY THE AFTERNOON.
GIVEN THE WAA ON RETURN FLOW...TEMPERATURE GUIDANCE SUPPORTS HIGH
TEMPERATURES WITHIN A DEGREE OR TWO OF FRIDAY/S VALUES. A FEW PRE
FRONTAL RAIN SHOWERS MAY REACH THE EXTREME WESTERN NC MTNS DURING
THE EARLY EVENING HOURS ON SATURDAY...I WILL INDICATE CHC POPS WITH
LOW QPF.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 230 PM WEDNESDAY...A COMPLEX WX PATTERN IS EXPECTED IN THE
MEDIUM RANGE...AS SPLIT UPPER FLOW IN THE WEST WILL BE QUITE
ACTIVE...AND THE MODELS DISAGREE ON THE DETAILS.
SATURDAY NIGHT AND SUNDAY...ALREADY PLENTY OF DISAGREEMENT WITH A
LEADING LOW PRES SYSTEM LIFTING NE ACRS THE MID MS VLY TO THE GREAT
LAKES...DRAGGING A COLD FRONT ACRS THE TN VLY TO THE SRN
APPALACHIANS. THE 12Z GFS IS SIMILAR TO PREV FEW RUNS IN BEING
MOISTURE-STARVED...WITH MORE VEERED LLVL FLOW AND WEAK ISENT LIFT.
MEANWHILE...THE 00Z ECMWF CONTINUES TO BE MUCH WETTER...WITH DEEP
SWLY FLOW TRANSPORTING GULF MOISTURE AHEAD OF THE FRONT...WITH
PLENTY OF LLVL LIFT. THE HPC GUIDE TAKES A BLEND OF THE GFS AND
ECMWF WITH THIS SYSTEM...WHICH RESULTS IN GENERALLY LOW-END
POPS...EXCEPT IN THE WEST WHERE THE BEST MOISTURE AND FORCING WILL
BE. TEMPS ARE EXPECTED TO BE TOO WARM FOR ANY WINTRY PRECIP WITH
THIS FIRST FRONT.
BOTH THE GFS AND ECMWF TAKE SOUTHERN STREAM SHORTWAVE ENERGY ACRS
THE SOUTHERN PLAINS...INDUCING WEAK CYCLOGENESIS ALONG A STALLED
FRONTAL BNDRY INVOF THE MID SOUTH. BUT THEY DIFFER ON THE
TIMING...WITH THE ECMWF ABOUT 12 HOURS FASTER. AN HPC BLEND WITH
PREVIOUS FCST WAS USED...RESULTING IN A SHOTGUN 30-40 POP FOR THREE
PERIODS FROM MONDAY THRU TUESDAY. THEN THINGS DRY OUT QUICKLY
TUESDAY NIGHT THRU WEDNESDAY. THIS ALSO RESULTS IN NO WINTRY PRECIP
IN THE FCST...AS CENTER OF LOW PRES LIFTS NE...KEEPING THE FA IN THE
WARM SECTOR. THERE MAY BE INSTBY AND SHEAR FOR SEVERE WX ACRS
PORTIONS OF THE PIEDMONT IF THE LOW IS STRONG ENUF AND TAKES THIS
KIND OF TRACK. AS I TYPED THIS...THE 12Z ECMWF CAME IN. IT HAS
ANOTHER SOUTHERN STREAM SYSTEM QUICKLY DEVELOP TUESDAY AND CROSS TO
OUR SOUTH...TURNING INTO A NOREASTER THAT RIDES UP THE EAST COAST
TUESDAY NIGHT THRU THURSDAY. THIS IS A NEW DEVELOPMENT...SO IS NOT
IN THIS FCST PACKAGE.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
AT KCLT...PATCHES OF LIGHT RAIN WILL MOVE OVER OR NEAR THE AIRFIELD
THIS EVENING. DO NOT EXPECT ANY VSBY RESTRICTIONS WITH THIS PRECIP.
OTHERWISE...MVFR CIGS WILL CONTINUE OVERNIGHT...WITH CIGS LESS THAN
2K FT LATE TONIGHT. DRIER AIR BEGINS TO MOVE IN BEHIND THIS SYSTEM
AFTER DAYBREAK. EXPECT LOW VFR TO DEVELOP BY MID MORNING THEN
SCATTER OUT BY NOON. NELY WINDS WITH LOW END GUSTS WILL CONTINUE
THRU THE EVENING AND COULD REDEVELOP WITH MIXING THU MORN.
OTHERWISE...WIND SPEEDS WILL REMAIN AROUND 10 KTS UNTIL LATE
AFTERNOON WHEN THE SLACKEN.
ELSEWHERE...SIMILAR CONDITIONS TO KCLT. EXPECT MVFR AT KAVL TO LIFT
AFTER MIDNIGHT WITH LOW VFR TIL NEAR DAYBREAK. KHKY SHUD SEE LOW VFR
UNTIL NEAR DAYBREAK. CIGS GO LOW VFR EARLIER AT THE SC SITES. ALL
AREAS SCATTER OUT BEFORE NOON. NELY WINDS WITH LOW END GUSTS AT ANY
TIME FOR SC WITH LOWER SPEEDS AT KHKY AND NLY WINDS AT KAVL
OVERNIGHT AND THU MORN. LIGHTER WINDS DEVELOP BY LATE AFTERNOON.
OUTLOOK...VFR CONDITIONS ARE EXPECTED THURSDAY NITE AND FRIDAY
THANKS TO HIGH PRESSURE BUILDING IN FROM THE WEST. MOISTURE AND THE
CHANCES OF RESTRICTIONS WILL INCREASE OVER THE WEEKEND.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...MCAVOY/RWH
SHORT TERM...NED
LONG TERM...ARK
AVIATION...RWH
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
651 PM EST WED DEC 12 2012
.SYNOPSIS...
HIGH PRESSURE WILL PERSIST OVER THE AREA INTO SATURDAY. A FRONTAL
SYSTEM WILL THEN APPROACH THE NORTH CAROLINA MOUNTAINS EARLY SUNDAY
AND CROSS EAST OF THE FORECAST AREA BY EARLY MONDAY. ANOTHER FRONTAL
SYSTEM WILL APPROACH THE REGION ON TUESDAY.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 650 PM... AREAS OF LIGHT RAIN WILL MOVE BACK INTO THE AREA
THIS EVENING AHEAD OF A SHORT WAVE AND DEVELOPING UPPER DIVERGENCE
ASSOCIATED WITH THE RIGHT ENTRANCE REGION OF THE POLAR JET. EVEN
WITH A STRONG COLD POOL MOVING ACROSS OR NEAR THE AREA...EXPECT ANY
HEAVIER SHRA TO REMAIN SOUTH OF THE CWFA. THAT SAID...CANNOT RULE
OUT A HEAVIER SHRA OVER THE SRN CWFA WITH SOME VERY SMALL HAIL OR
GRAUPEL. ANY OF THESE WOULD BE SHORT LIVED. 18Z GUIDANCE KEEPS THE
PRECIP AND LOW CLOUDS IN A LITTLE LONGER THAN PREV GUIDANCE. HAVE
FOLLOWED THESE TRENDS WITH THE FCST GIVEN THE POSITION AND MOVEMENT
OF UPSTREAM PRECIP. MADE SOME MINOR ADJUSTMENTS TO OVERNIGHT LOWS IN
LINE WITH THIS GUIDANCE AS WELL. LOW END GUSTY WINDS WILL DEVELOP
FROM TIME TO TIME TONIGHT AND EARLY THU MORN.
PREVIOUS DISCUSSION...STRONG UPPER DIVERGENCE IN THE ENTRANCE REGION
OF A 130 KT POLAR JET HAS RESULTED IN LIGHT RAIN OVER PARTS OF THE
UPSTATE AND THE SRN NC PIEDMONT. THE LATEST RUC SHOWS THE DIVERGENCE
WEAKENING FOR A FEW HOURS THIS AFTERNOON...THEN INCREASING OVER THE
SRN HALF OF THE FORECAST AREA AGAIN EARLY THIS EVENING AS A SHORT
WAVE CURRENTLY OVER MISSISSIPPI EJECTS QUICKLY TO THE NE. THE GFS
ALSO HAS AN IMPRESSIVE QPF MAX OVER THE SRN PART OF THE UPSTATE AND
CHARLOTTE METRO AREA FROM 00-06 UTC THIS EVENING. WHILE IT/S
0.25-0.50 INCH RAINFALL AMOUNTS ARE ALMOST CERTAINLY TOO
HIGH...LIGHT RAIN SHOULD FILL BACK IN THIS EVENING ACROSS THE SAME
AREAS THAT HAVE BEEN SEEING IT THIS AFTERNOON. THIS WILL BASICALLY
BE AREAS ALONG AND SOUTH OF I-85. IT STILL APPEARS THAT THE RAIN
WILL END BEFORE TEMPERATURES FALL BELOW FREEZING TONIGHT AND I/M NOT
ANTICIPATING ANY P-TYPE PROBLEMS OVERNIGHT. EVEN DURING THE DAYLIGHT
HOURS TODAY THE PCPN SHOULD BE ALL RAIN. WHILE THE DUAL-POL
HYDROMETEOR CLASSIFICATION ALGORITHM IS SHOWING SOME MIXED PCPN OVER
THE CHARLOTTE METRO AREA...THIS IS UP AT 7KFT AND IS NOT REFLECTIVE
OF WHAT IS FALLING AT THE SFC. LAPS SOUNDINGS OVER THIS AREA SHOW
AIR TEMPS WELL ABOVE FREEZING IN THE LOWEST SEVERAL THOUSAND FEET OF
THE ATMOSPHERE.
CLOUDS WILL CLEAR OUT OF THE EASTERN ZONES EARLY TOMORROW AND WE
SHOULD SEE CLEAR BLUE SKIES AND SLIGHTLY BELOW NORMAL TEMPERATURES
FOR THURSDAY.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 2 PM WEDNESDAY...SHORT RANGE MODELS INDICATE THAT THE
FORECAST AREA WILL REMAIN WITHIN THE CENTER OF 1025 MB SFC HIGH AND
UNDER DEEP RIDGING ALOFT. FORECAST SOUNDINGS INDICATE THAT WIDE
DEWPOINT DEPRESSIONS WILL EXIST FROM THE SFC TO THE
TROPOPAUSE...SUPPORTING A 0 PERCENT SKY COVER FORECAST FRIDAY
MORNING. HOWEVER...CIRRUS LEVEL MOISTURE WILL BEGIN TO INCREASE
DURING THE AFTERNOON...LIKELY SUPPORTING A FEW CONTRAILS OR THIN
CIRRUS. CALM WINDS...CLEAR SKY...AND DEEP DRY AIR WILL PROVIDE GOOD
RADIATIONAL COOLING CONDITIONS FRIDAY MORNING. USING A BLEND OF MOS
GUIDANCE...MIN TEMPERATURES SHOULD RANGE FROM THE MID 20S ACROSS THE
MTN VALLEYS TO THE L30S EAST. UNDER SUNNY TO MOSTLY SUNNY
CONDITIONS...HIGH TEMPERATURES ARE FORECAST TO RANGE FROM THE U50S
ACROSS THE MTNS TO THE L60S EAST.
FRIDAY NIGHT...CIRRUS CLOUD COVER WILL INCREASE THROUGH THE
NIGHT...POSSIBLY BECOMING GREATER THAN 5KFT THICK BY 12Z SAT. SFC
CONDITIONS WILL LIKELY REMAIN DRY WITH LIGHT AND VARIABLE TO CALM
WINDS. HOWEVER...THE INCREASING SKY COVER WILL FAVOR MIN
TEMPERATURES AROUND 5 DEGREES WARMER THAN EXPECTED FRIDAY MORNING.
ON SATURDAY...A COLD FRONT WILL APPROACH FROM THE WEST...LIKELY
REMAINING WEST OF THE APPALACHIAN THROUGH 0Z SUNDAY. HOWEVER...LIGHT
RETURN FLOW WILL DEVELOP ACROSS THE FORECAST AREA...RESULTING IN
WEAK WAA. FORECAST SOUNDINGS INDICATE THAT CLOUD BASES WILL LOWER TO
AROUND 10 KFT BY THE LATE AFTERNOON...REMAINING RATHER THICK ALOFT.
CLOUD COVER IS FORECAST TO BECOME MOSTLY CLOUDY BY THE AFTERNOON.
GIVEN THE WAA ON RETURN FLOW...TEMPERATURE GUIDANCE SUPPORTS HIGH
TEMPERATURES WITHIN A DEGREE OR TWO OF FRIDAY/S VALUES. A FEW PRE
FRONTAL RAIN SHOWERS MAY REACH THE EXTREME WESTERN NC MTNS DURING
THE EARLY EVENING HOURS ON SATURDAY...I WILL INDICATE CHC POPS WITH
LOW QPF.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 230 PM WEDNESDAY...A COMPLEX WX PATTERN IS EXPECTED IN THE
MEDIUM RANGE...AS SPLIT UPPER FLOW IN THE WEST WILL BE QUITE
ACTIVE...AND THE MODELS DISAGREE ON THE DETAILS.
SATURDAY NIGHT AND SUNDAY...ALREADY PLENTY OF DISAGREEMENT WITH A
LEADING LOW PRES SYSTEM LIFTING NE ACRS THE MID MS VLY TO THE GREAT
LAKES...DRAGGING A COLD FRONT ACRS THE TN VLY TO THE SRN
APPALACHIANS. THE 12Z GFS IS SIMILAR TO PREV FEW RUNS IN BEING
MOISTURE-STARVED...WITH MORE VEERED LLVL FLOW AND WEAK ISENT LIFT.
MEANWHILE...THE 00Z ECMWF CONTINUES TO BE MUCH WETTER...WITH DEEP
SWLY FLOW TRANSPORTING GULF MOISTURE AHEAD OF THE FRONT...WITH
PLENTY OF LLVL LIFT. THE HPC GUIDE TAKES A BLEND OF THE GFS AND
ECMWF WITH THIS SYSTEM...WHICH RESULTS IN GENERALLY LOW-END
POPS...EXCEPT IN THE WEST WHERE THE BEST MOISTURE AND FORCING WILL
BE. TEMPS ARE EXPECTED TO BE TOO WARM FOR ANY WINTRY PRECIP WITH
THIS FIRST FRONT.
BOTH THE GFS AND ECMWF TAKE SOUTHERN STREAM SHORTWAVE ENERGY ACRS
THE SOUTHERN PLAINS...INDUCING WEAK CYCLOGENESIS ALONG A STALLED
FRONTAL BNDRY INVOF THE MID SOUTH. BUT THEY DIFFER ON THE
TIMING...WITH THE ECMWF ABOUT 12 HOURS FASTER. AN HPC BLEND WITH
PREVIOUS FCST WAS USED...RESULTING IN A SHOTGUN 30-40 POP FOR THREE
PERIODS FROM MONDAY THRU TUESDAY. THEN THINGS DRY OUT QUICKLY
TUESDAY NIGHT THRU WEDNESDAY. THIS ALSO RESULTS IN NO WINTRY PRECIP
IN THE FCST...AS CENTER OF LOW PRES LIFTS NE...KEEPING THE FA IN THE
WARM SECTOR. THERE MAY BE INSTBY AND SHEAR FOR SEVERE WX ACRS
PORTIONS OF THE PIEDMONT IF THE LOW IS STRONG ENUF AND TAKES THIS
KIND OF TRACK. AS I TYPED THIS...THE 12Z ECMWF CAME IN. IT HAS
ANOTHER SOUTHERN STREAM SYSTEM QUICKLY DEVELOP TUESDAY AND CROSS TO
OUR SOUTH...TURNING INTO A NOREASTER THAT RIDES UP THE EAST COAST
TUESDAY NIGHT THRU THURSDAY. THIS IS A NEW DEVELOPMENT...SO IS NOT
IN THIS FCST PACKAGE.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AT KCLT...PATCHES OF LIGHT RAIN WILL MOVE OVER OR NEAR THE AIRFIELD
THIS EVENING. DO NOT EXPECT ANY VSBY RESTRICTIONS WITH THIS PRECIP.
OTHERWISE...MVFR CIGS WILL CONTINUE OVERNIGHT...WITH CIGS LESS THAN
2K FT LATE TONIGHT. DRIER AIR BEGINS TO MOVE IN BEHIND THIS SYSTEM
AFTER DAYBREAK. EXPECT LOW VFR TO DEVELOP BY MID MORNING THEN
SCATTER OUT BY NOON. NELY WINDS WITH LOW END GUSTS WILL CONTINUE
THRU THE EVENING AND COULD REDEVELOP WITH MIXING THU MORN.
OTHERWISE...WIND SPEEDS WILL REMAIN AROUND 10 KTS UNTIL LATE
AFTERNOON WHEN THE SLACKEN.
ELSEWHERE...SIMILAR CONDITIONS TO KCLT. EXPECT MVFR AT KAVL TO LIFT
AFTER MIDNIGHT WITH LOW VFR TIL NEAR DAYBREAK. KHKY SHUD SEE LOW VFR
UNTIL NEAR DAYBREAK. CIGS GO LOW VFR EARLIER AT THE SC SITES. ALL
AREAS SCATTER OUT BEFORE NOON. NELY WINDS WITH LOW END GUSTS AT ANY
TIME FOR SC WITH LOWER SPEEDS AT KHKY AND NLY WINDS AT KAVL
OVERNIGHT AND THU MORN. LIGHTER WINDS DEVELOP BY LATE AFTERNOON.
OUTLOOK...VFR CONDITIONS ARE EXPECTED THURSDAY NITE AND FRIDAY
THANKS TO HIGH PRESSURE BUILDING IN FROM THE WEST. MOISTURE AND THE
CHANCES OF RESTRICTIONS WILL INCREASE OVER THE WEEKEND.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...MCAVOY/RWH
SHORT TERM...NED
LONG TERM...ARK
AVIATION...RWH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
531 PM CST WED DEC 12 2012
.SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT
248 PM CST WED DEC 12 2012
FORECAST CONCERN REMAINS FOCUSED ON WEEKEND STORM SYSTEM AND THE
IMPACT ON OUR AREA.
WATER VAPOR LOOP THIS AFTERNOON SHOWING A TRANSITION TO A FAIRLY
HIGH-ZONAL FLOW ACROSS THE NORTHERN TIER CONUS. THE SURFACE MAP
SHOWS LOW PRESSURE OVER SOUTHERN MT/NORTHERN WY WIT A WARM
FRONTAL/STATIONARY FRONTAL BOUNDARY EXTENDING NORTHEAST THROUGH THE
DAKOTAS AND NORTHERN MN. SOUTHERLY FLOW ACROSS THE CENTRAL
PLAINS/UPPER MISSISSIPPI RIVER AND PARTIAL /FULL SUNSHINE HELPING TO
BOOST TEMPERATURES INTO THE MIDDLE 30S AND EVEN A FEW LOWER/MID 40
READINGS ACROSS PARTS OF NORTHEAST IA INTO FAR SOUTHWEST WI.
12.12Z NCEP MODELS ALONG WITH EC AND SREF ALL IN GOOD AGREEMENT
THROUGH THE NEAR SHORT TERM PERIOD...AND REMAIN IN AGREEMENT THAT A
STORM SYSTEM WILL DEFINITELY BE AFFECTING THE AREA FRIDAY NIGHT
THROUGH SATURDAY NIGHT. QUESTION REMAINS ON EXACT TRACK OF THE LOW
AND RESULTING PRECIPITATION TYPES.
QUIET/DRY CONDITIONS EXPECTED THROUGH FRIDAY WITH A COUPLE MID-LEVEL
TROUGHS RIPPLING THROUGH THE FLOW ALONG THE U.S./CANADIAN BORDER.
THIS KEEPS BULK OF MID/HIGH CLOUD AND ANY PRECIPITATION CHANCES
NORTH OF THE AREA WITH RELATIVELY MILD FLOW PREVAILING. BASED ON
TEMPERATURE TREND TODAY...HAVE BUMPED HIGHS UP A FEW DEGREES
THURSDAY AND ESPECIALLY FRIDAY AS 925MB TEMPERATURES WARMING INTO
THE 0 TO +7C.
FOCUS THEN SHIFTS TO STORM SYSTEM MOVING OUT OF THE CENTRAL ROCKIES
TOWARD THE AREA FRIDAY NIGHT/SATURDAY. MODELS ALL IN GOOD AGREEMENT
THAT PRECIPITATION WILL BREAK OUT SOON AFTER MIDNIGHT WEST OF THE
MISSISSIPPI RIVER...AND EAST OF THE RIVER BETWEEN 3 AM AND 6 AM.
MODELS SOUNDINGS/THERMAL PROFILES FAIRLY TRICKY WITH THIS SYSTEM.
APPEARS AREAS ALONG AND SOUTH OF I-90 WILL SEE MOSTLY RAIN WITH
SURFACE TEMPERATURES AS RISING AT THE ONSET. FARTHER NORTH ACROSS
THE I-94 CORRIDOR AND NORTH...LOOKS LIKE A WINTRY MIX OF SLEET/SNOW
AND FREEZING RAIN COULD OCCUR. FOR SATURDAY MORNING...WILL LIKELY
SEE MOSTLY RAIN SOUTH OF I-94 WITH A WINTRY MIX REMAINING NORTH OF
I-94. FOR SATURDAY AFTERNOON AS DYNAMIC COOLING TAKES PLACE WITH
SURFACE/UPPER LEVEL LOW TRACKING OVERHEAD...LOOKING FOR A TRANSITION
TO SNOW NORTHWEST OF A LINE FROM NEAR NEILSVILLE AND WINONA...DOWN
THROUGH PRESTON MN AND CHARLES CITY IA. SO...BOTTOM LINE...COULD BE
SOME ICE ISSUES FOR LATE FRIDAY NIGHT INTO SATURDAY MORNING...THEN
SOME ACCUMULATING SNOW FOR NORTHWESTERN PORTIONS OF OF THE FORECAST
AREA GOING INTO THE AFTERNOON HOURS. SOME LIGHT SNOW/RAIN
TRANSITIONING TO ALL SNOW MAY LINGER INTO SATURDAY EVENING ON THE
BACK SIDE OF THE LOW WITH COLD AIR ADVECTION FILLING IN ACROSS THE
AREA. WILL HAVE TO KEEP A CLOSE EYE ON THE TRACK AND DYNAMICS OF
THIS STORM SYSTEM. IF CURRENT TRENDS REMAIN IN TACT...WILL PROBABLY
BE LOOKING AT EVENTUAL ISSUANCE OF WINTER WEATHER HEADLINES.
.LONG TERM...SUNDAY THROUGH WEDNESDAY
248 PM CST WED DEC 12 2012
NOT TOO GOOD OF AGREEMENT BETWEEN THE 12.12Z GFS AND ECMWF. THE
ECMWF KEEPS FAIRLY DEEP/COOLER CYCLONIC FLOW LINGERING ACROSS THE AREA
THROUGH WEDNESDAY WHEREAS THE GFS MOVES THE TROUGH EAST WITH A FLAT
RIDGE BUILDING IN. EITHER WAY...LOOK OVERALL DRY THROUGH THE PERIOD
WITH MODEL CONSENSUS HIGH TEMPERATURES RUNNING CLOSE TO NORMAL IN
THE 20S TO MIDDLE 30S.
&&
.AVIATION...TONIGHT AND THURSDAY
531 PM CST WED DEC 12 2012
VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD...WITH JUST A
SCATTERED TO BROKEN DECK OF HIGH CLOUDS. OF MORE CONCERN IS THE
STRONGER LOW LEVEL JET IN PLACE. 12.21Z RAP AND 12.18Z NAM BUFKIT
SOUNDINGS CONTINUE TO SHOW 50 KNOT WINDS AT O15K FEET THROUGHOUT
THE NIGHT AND THUS HAVE CONTINUED THE MENTION OF LLWS AT BOTH
SITES AS SURFACE WINDS ARE EXPECTED TO DROP INTO THE 10 TO 15 KNOT RANGE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
248 PM CST WED DEC 12 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
257 PM CST TUE DEC 11 2012
.SYNOPSIS...QUIET WEATHER WITH A LITTLE ABOVE NORMAL TEMPERATURES
FOR THE REST OF THE WORK WEEK...THEN SOME PRECIPITATION THIS
WEEKEND.
THE LARGE SCALE PATTERN ACRS NOAM WL GRADUALLY TRANSITION INTO A
SPLIT FLOW REGIME BY THIS WEEKEND. THIS WL ALLOW TEMPS TO WARM
BACK TO SOMEWHAT TO ABV NORMAL. THE MAIN PCPN EVENT WL COME WITH
SRN STREAM CYCLONE TRACKING THROUGH THE RGN THIS WEEKEND.
&&
.SHORT TERM...TONIGHT AND WEDNESDAY.
SNOW POTENTIAL AND TEMPERATURES WERE THE MAIN CONCERNS FOR THE SHORT
TERM. WV IMAGERY SHOWED SHORT WAVES PASSING THROUGH THE WESTERN
GREAT LAKES REGION TODAY. MODELS SEEMED TO AGREE THAT THE SHORT
WAVE OVER MINNESOTA EARLY THIS AFTERNOON WOULD PRODUCE SOME QPF
ACROSS THE FAR SOUTHERN PART OF THE FORECAST AREA THIS EVENING AS
IT MOVES THROUGH WISCONSIN. HAVE OPTED TO INCLUDE POPS A BIT
FARTHER NORTH IN TEXT PRODUCTS THAT IN GRIDS...TO PROVIDE SOME
MARGIN FOR ERROR.
A NARROW SURFACE RIDGE IS EXPECTED TO PUSH EAST TONIGHT...RESULTING
IN DECREASING WINDS. MODELS WERE KEEPING SOME LOWER LEVEL MOISTURE
AROUND SO HAVE 50 PERCENT OR HIGHER SKY COVER THROUGHOUT THE
NIGHT. THE LIGHT WINDS SHOULD STILL ALLOW TEMPERATURES TO FALL INTO
THE SINGLE DIGITS AND TEENS WITHOUT MUCH CLEARING. IF CLOUDS DO
NOT HANG AROUND TEMPERATURES WILL LIKELY END UP MUCH COLDER...EVEN
WITH WAA OCCURRING.
THERE SHOULD STILL BE SOME MIDDLE AND HIGH CLOUDS ACROSS THE AREA
ON WEDNESDAY ACCORDING TO MODEL TIME/HEIGHT SECTIONS SO FULL
SUNSHINE IS NOT LIKELY. CONTINUED WARM ADVECTION SHOULD RESULT IN
WARMER HIGH TEMPERATURES THAT TODAY...AT OR A SLIGHTLY WARMER THAN
NORMAL. 850MB BAROCLINIC ZONE SHOULD BE NORTH OF THE STATE AND
THERE WAS NO QPF SHOWING UP ON GRAPHICS SO HAVE KEPT THE FORECAST
DRY DURING THE DAY.
.LONG TERM...WED NGT THRU NEXT TUE. RELATIVELY QUIET WX EXPECTED
FOR THE REST OF THE WORK WEEK. WLY FLOW ALOFT WL ALLOW TEMPS TO
WARM BACK TO AT LEAST SOMEWHAT ABV NORMAL...THOUGH DEEP SNOWCOVER
TO THE WEST AND VERY LOW SUN ANGLE AT THIS TIME OF YR WL KEEP THE
WARMING IN CHECK.
SRN STREAM CYCLONE TRACKING THROUGH THE RGN WL PROBABLY BRING PCPN
TO THE AREA THIS WEEKEND. MODELS WERE SIMILAR IN SHOWING THE
SYSTEM AFFECTING THE AREA...BUT DIFFERED SOMEWHAT ON THE TRACK.
PCPN CHCS WL BE SOMEWHAT GREATER OVER THE S AND DECR TO THE N. AS
TYPICAL OF SUCH SYSTEMS...PCPN TYPE WL BE A MAJOR FCST ISSUE.
&&
.AVIATION...SHORT WAVES PASSING THROUGH THE AREA TODAY WERE
PRODUCING SNOW SHOWERS AND FLURRIES...ALONG WITH MAINLY MVFR CIGS
AND MVFR/IFR VSBYS. RUC13 SHOWED A TENDENCY FOR SHORT WAVES TO
WEAKEN...OR AT LEAST PRODUCE SMALL OR NO QPF AS THEY MOVE INTO THE
EASTERN PART OF THE FORECAST AREA. MVFR CIGS MAY PERSIST THROUGH
THE EVENING BEFORE LOW CLOUDS START TO CLEAR...LEAVING JUST SOME HIGH
CLOUDS. LOOKS DRY AFTER 06Z AND WEDNESDAY SHOULD BE DRY WITH VFR
CONDITIONS PREVAILING.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MG/SKOWRONSKI
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1216 PM CST TUE DEC 11 2012
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
.SHORT TERM...TODAY THROUGH WEDNESDAY...SNOW CHANCES TODAY AND
EARLY TONIGHT...AND SKY COVER AND TEMPERATURES THROUGHOUT THE
PERIOD...ARE THE MAIN FCST CONCERNS.
WV IMAGERY SHOWED A S/W TROF MOVG THROUGH NE WI...AND ADDITIONAL SHORT-
WAVES LOCATED UPSTREAM OVER MINNESOTA AND SE SASK. THESE DISTURBANCES
WILL PASS THROUGH GRB CWA TODAY INTO THIS EVENING...PRODUCING SCT SNOW
SHOWERS AND FLURRIES. THERE WILL BE PERIODIC BREAKS IN THE SNOW SHOWERS
DUE TO SUBSIDENCE BETWEEN THE WAVES. EVEN THOUGH THERE IS ONLY A SMALL
CHANCE OF MEASURABLE WATER EQUIVALENT PCPN...TEMPERATURES WITHIN
THE MOISTURE LAYERS ARE FAVORABLE FOR DENDRITES...SO MOST PLACES
SHOULD RECEIVE A DUSTING TO A HALF INCH OF FLUFFY SNOW. THE SNOW
WILL END AS THE FINAL S/W TROF EXITS THE REGION AND A RIDGE OF
HIGH PRESSURE ARRIVES AFTER MIDNIGHT. THIS RIDGE SHOULD BRING
PARTIAL CLEARING OVERNIGHT...LEADING TO COOLER TEMPS IN THE SINGLE
DIGITS AND TEENS.
WAA WILL CAUSE H8 TEMPS TO WARM TO AROUND ZERO C BY WEDNESDAY...BUT
FCST SOUNDINGS ONLY SUPPORT SHALLOW MIXING TO 950-925 MB. LINGERING
SNOW PACK MAY HINDER A GOOD WARM-UP...SO DIDN`T STRAY TOO FAR FROM
PREVIOUS FCST HIGHS...WHICH RANGED FROM THE UPPER 20S TO MID 30S.
.LONG TERM...WEDNESDAY NIGHT THROUGH NEXT MONDAY.
THE LATEST GFS ENSEMBLE MEAN INDICATES THAT SPLIT FLOW WILL DOMINATE
THE WEATHER PATTERN ACROSS NORTH AMERICA THROUGHOUT THE EXTENDED
FORECAST. WITH THE STATE OF WISCONSIN LOCATED BETWEEN THE NORTHERN
STREAM WHICH WILL GENERALLY RESIDE JUST NORTH OF THE CANADIAN
BORDER...AND THE SOUTHERN STREAM OVER THE MID-MISSISSIPPI VALLEY...A
PERIOD OF QUIET WEATHER IS EXPECTED. THE ONLY WEATHER-MAKER OVER
THIS PERIOD WILL OCCUR EARLY THIS WEEKEND WHEN A SYSTEM EJECTS OUT
OF THE SW CONUS AND MOVES ACROSS THE CENTRAL MISSISSIPPI VALLEY TO
THE SOUTH-CENTRAL GREAT LAKES. THE GFS IS QUITE FAST...BUT ITS
TRACK LOOKS LIKE IN THE MIDDLE OF THE GUIDANCE. WILL TAKE A BLEND
OF THE ECMWF/GEM.
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...A WEAK AREA OF LOW PRESSURE
WILL MOVE FROM NORTHERN MINNESOTA AND ACROSS LAKE SUPERIOR WEDNESDAY
NIGHT THROUGH THURSDAY MORNING. FORCING WILL RESIDE ALONG AND NORTH
OF THE SURFACE LOW TRACK...WHILE DRY LOW LEVEL AIR WILL PUSH NORTH
ACROSS THE STATE FROM THE SOUTHERN PLAINS. THE DRY AIR WILL KEEP
THE AREA PRECIP-FREE...THOUGH PARTLY CLOUDY CONDITIONS WILL REMAIN
THANKS TO A CIRRUS SHIELD...AND SW WINDS WILL BE QUITE BREEZY.
TEMPS WILL BE MILD WITH HIGHS IN THE MID TO UPPER 30S ON THURSDAY.
A COLD FRONT EXTENDING SW FROM THE SURFACE LOW WILL SLOWLY SAG INTO
THE REGION THURSDAY NIGHT. A BKN LOW CLOUD DECK WILL TRY TO MOVE
INTO N-C WISCONSIN BEHIND THE FRONT. BUT OTHERWISE...A LACK OF
FORCING ALOFT WILL PREVENT ANY THREAT OF PRECIP. LOWS IN THE MID
TEENS TO LOWER 20S.
REST OF THE FORECAST...DIFFUSE COOL FRONT WILL SLOWLY SAG SOUTH
ACROSS THE FORECAST AREA FRIDAY INTO FRIDAY NIGHT WITHOUT MUCH
OF AN IMPACT EXCEPT FOR A LOW STRATUS DECK THAT MAY SLIDE INTO
NORTHERN WISCONSIN. HIGH CLOUDS WILL BE INCREASING FRIDAY NIGHT AS
A STORM SYSTEM MOVES ACROSS THE CENTRAL PLAINS. THERE IS A SMALL
CHANCE THAT PRECIP FROM THE SYSTEM WILL REACH CENTRAL WISCONSIN LATE
FRIDAY NIGHT...BUT WILL PROBABLY HAVE TO WAIT UNTIL SATURDAY WHEN
LOW PRESSURE MOVES ACROSS CENTRAL TO NORTHEAST ILLINOIS. ISENTROPIC
ASCENT WILL BE INCREASING AHEAD OF THIS SYSTEM ON SATURDAY TO SPREAD
PRECIP NORTHEAST ACROSS THE REGION. PRECIP TYPE WILL AGAIN BE TOUGH
TO NAIL DOWN...BUT MILD PACIFIC AIR IN PLACE COMBINED WITH A DAYTIME
ARRIVAL OF THE PRECIP MAKES ME THINK A RAIN/SNOW MIX ACROSS MUCH OF
THE AREA EXCEPT FOR NORTH-CENTRAL WISCONSIN. PRECIP WILL CONTINUE
INTO SATURDAY NIGHT WHEN COOLING LOW LEVEL TEMPS WILL LEAD TO ACCUM
SNOW CHANCES FARTHER SOUTH. LIGHT SNOW SHOWERS AND FLURRIES WILL
CONTINUE THROUGH SUNDAY THANKS TO CYCLONIC FLOW. QUIET CONDITIONS
RETURN ON MONDAY.
&&
.AVIATION...SHORT WAVES PASSING THROUGH THE AREA TODAY WERE
PRODUCING SNOW SHOWERS AND FLURRIES...ALONG WITH MAINLY MVFR CIGS
AND MVFR/IFR VSBYS. RUC13 SHOWED A TENDENCY FOR SHORT WAVES TO
WEAKEN...OR AT LEAST PRODUCE SMALL OR NO QPF AS THEY MOVE INTO THE
EASTERN PART OF THE FORECAST AREA. MVFR CIGS MAY PERSIST THROUGH
THE EVENING BEFORE LOW CLOUDS START TO CLEAR...LEAVING JUST SOME HIGH
CLOUDS. LOOKS DRY AFTER 06Z AND WEDNESDAY SHOULD BE DRY WITH VFR
CONDITIONS PREVAILING.
MG
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1045 PM CST MON DEC 10 2012
.SHORT TERM...TONIGHT THROUGH WEDNESDAY
725 PM CST MON DEC 10 2012
725 PM UPDATE...LATEST RADAR IMAGERY...WEB CAM HERE AT OUR OFFICE
AS WELL AS THE 01Z OBSERVATION FROM KOVS ALL SHOWING AN INCREASE
IN SNOW DEVELOPMENT IN THE STRATUS DECK THAT ENCOMPASSES MOST
LOCATIONS ALONG AND EAST OF THE MISSISSIPPI RIVER. BEST GUESS IS
THAT THERE IS SOME INCREASING TURBULENCE IN THE STRATUS DECK AHEAD
OF THE HIGH PRESSURE RIDGE BUILDING INTO THE AREA...AND GIVEN THAT
THE STRATUS DECK LIES IN THE DENDRITIC GROWTH ZONE PER 00Z GRB/DVN
SOUNDINGS...IT DOES NOT TAKE MUCH TO GET SNOW GOING. OVER THE LAST
TWO HOURS...THE MOTION OF THE SNOW ON RADAR IS FOLLOWING AN
EASTWARD PROGRESSION AROUND 11 KT. HAVE USED THIS MOTION IN
SHOWING AN EXTRAPOLATION OF THE CURRENT RADAR IMAGERY FOR THE
PRECIPITATION CHANCE FORECAST THROUGH THE NIGHT. REGARDING THE
CHANCES...GIVING THAT WE ARE DEALING WITH DENDRITES AND THE
FORCING IS WEAK AT BEST...IT IS LIKELY WE MAY NOT SEE MUCH LIQUID
EQUIVALENT QPF OUT OF THIS. HOWEVER...A FEW TENTHS OF AN INCH OF
SNOW COULD ACCUMULATE. SINCE THE PRECIPITATION CHANCE DEFINITION
IS FOR A 0.01 OF LIQUID EQUIVALENT...ONLY HAVE 20 TO 30 PERCENT
CHANCES AT THE MOMENT WITH UP TO A HALF INCH OF SNOWFALL
ACCUMULATION.
PREVIOUS DISCUSSION ISSUED AT 332 PM...
AT 3 PM...LOW CLOUDS PERSISTED ACROSS MUCH OF THE FORECAST AREA.
THIS MOISTURE WAS TRAPPED BELOW A SUBSIDENCE INVERSION. THE
VISIBLE AND FOG PRODUCT /11-3.9 MICRON CHANNEL/ SHOW THAT THE
CLOUDS ARE STARTING TO BREAK UP IN THE DODGE CENTER...AUSTIN...
CHARLES CITY AREAS. THE RAP SEEMS TO BE HANDLING THIS THE BEST.
THEY SHOW THAT A NARROW AREA OF CLEARING WILL MOVE EAST ACROSS
NORTHEAST IOWA AND SOUTHEAST MINNESOTA THIS EVENING. THIS AREA
REMAINS NARROW DUE TO ANOTHER AREA OF CLOUDS MOVING INTO THE
REGION FROM THE DAKOTAS. THIS CLEARING WILL ALLOW A RAPID DROP IN
TEMPERATURES DUE TO FRESH SNOW AND LIGHT WINDS...AND THEN THE
TEMPERATURES WILL RISE AS THE CLOUDS MOVE BACK INTO THE AREA.
ON TUESDAY AFTERNOON AND EVENING...A SHORT WAVE TROUGH WILL MOVE
ACROSS THE AREA. AHEAD OF THIS WAVE...MODERATE 270 TO 280K
ISENTROPIC LEADS TO SATURATION UP TO 775 MB. HOWEVER AS THE WAVE
IS MOVING THROUGH THE REGION...THERE IS VERY LITTLE OMEGA AND THE
LOW LEVEL LAPSE RATES ARE NOT THAT STEEP. AS A RESULT...NOT
EXPECTING ANY ACCUMULATING SNOW. HOWEVER WOULD NOT BE TOO
SURPRISED TO SEE A FEW FLURRIES. SINCE THIS WAVE IS CURRENTLY NOT
PRODUCING ANYTHING UPSTREAM AND THE FORCING AND MOISTURE LOOKS
SIMILAR...DID NOT INCLUDE THEM IN THE FORECAST AT THIS TIME.
ON WEDNESDAY...THE 500 MB FLOW BECOMES ZONAL. THIS KEEPS THE NEXT
2 SHORT WAVE TROUGHS /WEDNESDAY AND THURSDAY/ NEAR THE
U.S./CANADIAN BORDER. BOTH OF THESE SYSTEMS WILL DRAW WARMER AIR
INTO THE REGION. WHILE THE MODELS WERE PUSHING MUCH OF THE AREA
INTO THE 35 TO 45 DEGREE RANGE FOR HIGH TEMPERATURES...LOWERED THEM
A COUPLE OF DEGREES DUE TO THE SNOW PACK.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
332 PM CST MON DEC 10 2012
FROM FRIDAY NIGHT INTO SATURDAY NIGHT...THE MAIN CONCERN WILL BE THE
TRACK OF A SYSTEM MOVING OUT OF THE SOUTHWEST UNITED STATES. AS
THIS SYSTEM MOVES NORTHEAST IT WILL BRING WARM AIR AND GULF
MOISTURE WITH IT. PRECIPITABLE WATER VALUES CLIMB ANYWHERE FROM
150 TO 200 PERCENT OF NORMAL. BOTH THE ECMWF AND GEM HAVE A MUCH
FURTHER NORTH TRACK THAN THE GFS. AS A RESULT...THEY BRING RAIN
INTO SOUTHWEST WISCONSIN AND NORTHEAST IOWA...AND A WINTRY MIX OF
SNOW AND SLEET OR ALL SNOW ACROSS THE REMAINDER OF THE AREA FROM
FRIDAY NIGHT INTO SATURDAY...AND THE PRECIPITATION CHANGES OVER TO
ALL SNOW BEFORE IT ENDS ON SATURDAY NIGHT. MEANWHILE THE GFS IS
ABOUT 6 HOURS SLOWER AND IT ALSO IS FAR ENOUGH SOUTH THAT ONLY THE
AREAS SOUTH OF THE INTERSTATE 90 CORRIDOR WOULD SEE SNOW FROM THIS
SYSTEM. THE GFS ENSEMBLE CONTINUES TO SHOW A WIDESPREAD OF
SOLUTIONS. A FEW OF THEM ARE SIMILAR TO THE ECMWF AND GEM...BUT
THERE ARE ALSO A FEW THAT NO PRECIPITATION AT ALL. OVERALL THE
ECMWF HAS BEEN THE MOST CONSISTENT...SO TRENDED THE FORECAST
TOWARD IT.
&&
.AVIATION...THROUGH 06Z WEDNESDAY
1044 PM CST MON DEC 10 2012
A SURFACE RIDGE OF HIGH PRESSURE CROSSING THE TAF SITES HAS
YIELDED VFR CONDITIONS TO BEGIN THE FORECAST. TO THE WEST...A LOW
PRESSURE TROUGH HAS MOVED INTO WESTERN MINNESOTA. EXPECT THIS
TROUGH TO CROSS THE TAF SITES THIS MORNING. ALONG AND AROUND
IT...OBSERVATIONS ARE SHOWING A BAND OF MVFR STRATUS...THUS HAVE
MOVED UP THE TIMING OF THE MVFR CEILINGS TO 12Z AT KRST AND 13Z AT
KLSE. SOME LIGHT SNOW OR FLURRIES COULD OCCUR WITH THIS TROUGH AS
WELL...BUT CONFIDENCE AGAIN REMAINS TOO LOW TO MENTION. IF SNOW
DOES OCCUR...VISIBILITIES COULD BRIEFLY GO MVFR. IN THE WAKE OF
THE TROUGH...MODELS HAVE BEEN SUGGESTING AN EXPANSIVE MVFR STRATUS
TO MOVE IN. HOWEVER...SATELLITE AND SURFACE OBSERVATIONS ACROSS
THE DAKOTAS SHOW MAINLY VFR CONDITIONS. A FEW MVFR STRATOCUMULUS
ARE PRESENT...WHILE AT THE SAME TIME THERE ARE AREAS OF CLEAR
SKIES. GIVEN THE CONDITIONS UPSTREAM IN THE DAKOTAS...HAVE WENT
WITH THE IDEA OF A BROKEN VFR STRATUS DECK FOR THE AFTERNOON AND
EVENING. WITH THE TROUGH PASSAGE...EXPECT WINDS TO SWING AROUND
MORE WESTERLY AND INCREASE TO 10-15 KT. THE WINDS WILL DIMINISH IN
THE EVENING AS THE PRESSURE GRADIENT RELAXES SOME.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
332 PM CST MON DEC 10 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE/AJ
LONG TERM...BOYNE
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS MIAMI FL
101 AM EST THU DEC 13 2012
.AVIATION...
THE MAIN CONCERN FOR THE EARLY MORNING HOURS WILL BE LOW CEILING
AND VISIBILITY RESTRICTIONS WITH THE CAVEAT THAT THERE IS A LOT OF
UNCERTAINTY. REGIONAL OBSERVATIONS INDICATE FOG AND MIST ACROSS
CENTRAL AND WEST CENTRAL PORTIONS OF THE PENINSULA WITH
IFR VISIBILITY RESTRICTIONS. AND THE CURRENT GUIDANCE IS STRONGLY
HINTING AT LOW STRATUS AND/OR FOG DURING THE EARLY MORNING HOURS
TODAY. FOR NOW WENT ALONG WITH PREVIOUS TAF`S SUGGESTING CEILINGS
NEAR 1500 FT STARTING AROUND 09Z BUT GUIDANCE INDICATED CEILINGS
NEAR 700 FEET POSSIBLE. WILL AMEND AS NECESSARY BUT PERIODS OF IFR
CONDITIONS MAY BE POSSIBLE EARLY THIS MORNING.
60
&&
.PREV DISCUSSION... /ISSUED 1001 PM EST WED DEC 12 2012/
UPDATE...
THE EVENING SURFACE ANALYSIS SHOWED A FRONTAL BOUNDARY EXTENDING
SOUTHWEST ACROSS THE FLORIDA PENINSULA NORTH OF OUR LOCAL AREA AND
A DECENT DEWPOINT GRADIENT FROM NORTH TO CENTRAL FLORIDA.
OBSERVATIONS SHOWED MAINLY LIGHT SOUTH-SOUTHWEST FLOW SOUTH OF THE
BOUNDARY ACROSS SOUTH FLORIDA WITH DEWPOINTS RANGING FROM THE
UPPER 60S TO LOWER 70S. RECENTLY ANIMATED WATER VAPOR LOOP SHOWED
A FAIRLY STRONG SHORTWAVE TROUGH BEGINNING TO LIFT NORTHEAST
TOWARD THE CAROLINAS WITH PLENTY OF MID/UPPER MOISTURE SPREADING
NORTHEAST ACROSS THE STATE...WITH THE EXCEPTION BEING THE FLORIDA
PANHANDLE WHERE DRY AIR HAS BEGUN SPREAD EAST IN THE WAKE OF THE
SHORTWAVE TROUGH. THE LATEST RUC ANALYSIS HAS INITIALIZED WELL
WITH THESE SYNOPTIC FEATURES AND GENERALLY INDICATES THE FRONTAL
BOUNDARY CONTINUING TO SLOWLY MAKE ITS WAY SOUTH INTO OUR AREA
THROUGH THE REMAINDER OF THE NIGHT AND INTO THURSDAY. LIGHT WINDS
ALONG WITH THE POTENTIAL FOR SOME CLEARING COULD RESULT IN FOG
DEVELOPMENT THROUGH THE LATE NIGHT HOURS. THE LATEST SREF
PROBABILITIES REFLECT THIS POTENTIAL AND REMAIN QUITE AGGRESSIVE
INDICATING VISIBILITIES DROPPING TO LESS THAN A MILE AFTER 06Z AND
CONTINUING THROUGH DAYBREAK ACROSS THE INLAND LOCATIONS. THE
LATEST FORECAST PACKAGE WAS UPDATED...MAINLY TO REDUCE THE RAIN
CHANCES THIS EVENING. OTHERWISE...THE PREVIOUS FORECAST PACKAGE
REMAINS ON TRACK WITH NO OTHER UPDATES NECESSARY AT THIS TIME.
85/AG
PREV DISCUSSION... /ISSUED 641 PM EST WED DEC 12 2012/
AVIATION...WEAK COLD FRONT WILL MOVE ACROSS SOUTH FLORIDA EARLY
THURSDAY WITH EXTENSIVE CLOUD FIELD AHEAD OF THE FRONT. VERY
LITTLE SHRA ACTIVITY WITH ABUNDANT MID LEVEL DRY AIR. GUIDANCE
INDICATED IFR CIGS DEVELOPING AFT 06-08Z BUT CONFIDENCE NOT HIGH
ENOUGH TO GO WITH THAT BUT SSW-SW LIGHT WIND FLOW LESS THAN 5 KT
GIVES MORE CREDENCE TO THIS SET UP SO INTRODUCED MVFR CIGS
PERSISTING TO BTWN 13-15Z. SFC WIND WILL SHIFT TO THE NNW BEHIND
THE FRONT AT 8-10KT EARLY THURSDAY AND WILL ATTEMPT TO VEER TO THE
NNE LATE IN THE PERIOD. SO AT THIS TIME, ONLY INDICATED THIS AT KFLL.
KOB
PREV DISCUSSION... /ISSUED 308 PM EST WED DEC 12 2012/
A FEW STRONG STORMS ARE POSSIBLE NORTH OF ALLIGATOR ALLEY THIS
AFTERNOON INTO EARLY THIS EVENING...
DRIER AND COOLER WEATHER IS EXPECTED FOR LATE THIS WEEK INTO
THIS WEEKEND...
SHORT TERM...
A COLD FRONT OVER CENTRAL FLORIDA WILL CONTINUE TO MOVE SLOWLY
SOUTH THIS AFTERNOON AND SHOULD BE AROUND THE LAKE OKEECHOBEE AREA
TONIGHT. THIS WILL KEEP THE STEERING FLOW SOUTHWEST OVER THE CWA
THIS AFTERNOON AND KEEP THE DEEP TROPICAL MOISTURE IN PLACE.
AT THE SAME TIME...THE SHORTWAVE OVER THE EASTERN GULF OF MEXICO
WILL CONTINUE TO MOVE EAST THROUGH CENTRAL/SOUTH FLORIDA THIS
AFTERNOON. THESE TWO WEATHER SYSTEMS ALONG WITH THE DEEP TROPICAL
MOISTURE WILL ALLOW FOR SCATTERED SHOWERS AND THUNDERSTORMS TO
DEVELOP OVER MOST OF THE CWA THIS AFTERNOON INTO THIS EVENING WITH
THE HIGHEST CHANCE OVER THE LAKE OKEECHOBEE AREA.
THE 500 MB LEVEL OF THE ATMOSPHERE CONTINUES TO BE IN THE -9C TO
-10C FROM THE SPECIAL 18Z MIA SOUNDING THIS AFTERNOON. THIS SHOULD
ALLOW FOR A FEW STRONG STORMS TO DEVELOP THROUGH THE AFTERNOON AND
EARLY EVENING HOURS...ESPECIALLY AROUND THE LAKE OKEECHOBEE AND
NORTHEAST AREAS OF THE CWA. SO WILL CONTINUE TO MENTION STRONG
STORM WORDING IN THE HWO PRODUCT AND THE NORTHERN ZONES OF THE CWA
FOR THIS AFTERNOON INTO EARLY THIS EVENING.
PATCHY TO AREAS OF FOG ARE ALSO POSSIBLE OVER SOUTH FLORIDA
TONIGHT AHEAD OF THE COLD FRONT...AS THE WINDS WILL BE LIGHT FROM
THE SOUTHWEST ALONG WITH THE DEEP TROPICAL MOISTURE. SO WILL BE
ADDING FOG WORDING TO MOST OF THE CWA FOR LATE TONIGHT INTO EARLY
THURSDAY MORNING.
THURSDAY INTO THIS WEEKEND...
THE COLD FRONT OVER LAKE OKEECHOBEE WILL CONTINUE TO MOVE
SOUTHWARD THROUGH THE CWA THURSDAY MORNING AND INTO THE FLORIDA
KEYS THURSDAY AFTERNOON INTO THURSDAY NIGHT. THIS WILL ALLOW FOR
DRIER AIR TO START TO WORK INTO THE CWA FROM THE NORTH.
HOWEVER...THERE COULD STILL BE A FEW SHOWERS THAT COULD AFFECT THE
EAST COAST METRO AREAS ON THURSDAY. SO WILL CONTINUE THE SLIGHT
CHANCE OF POPS FOR THE EAST COAST METRO AREAS ON THURSDAY...BEFORE
GOING DRY FOR ALL OF SOUTH FLORIDA THURSDAY NIGHT. THE DRY WEATHER
WILL THEN CONTINUE TO REMAIN IN PLACE OVER SOUTH FLORIDA THIS
WEEKEND...AS HIGH PRESSURE BUILDS INTO THE SOUTHEAST UNITED STATES
FROM THE CENTRAL UNITED STATES.
TEMPERATURES WILL ALSO GET BACK TO MORE NEAR NORMAL CONDITIONS
OVER SOUTH FLORIDA THIS WEEKEND WITH HIGHS IN THE 70S TO AROUND 80
AND LOWS IN THE 50S INTERIOR AREAS TO 60S OVER THE METRO AREAS.
LONG TERM...
THE LONG RANGE MODELS CONTINUE TO SHOW A LOW PRESSURE DEVELOPING
IN THE CENTRAL UNITED STATES EARLY NEXT WEEK...BEFORE MOVING INTO
THE SOUTHEAST UNITED STATES BY MIDDLE OF NEXT WEEK. THE MODELS ARE
ALSO SHOWING THAT A STRONG COLD FRONT ASSOCIATED WITH THE LOW WILL
BE MOVING THROUGH SOUTH FLORIDA ON TUESDAY. HOWEVER...THE MODELS
ARE NOW SHOWING THAT MOST OF THE ENERGY WILL NOT BE MORE CLOSER TO
THE LOW AND NOT ALONG THE FRONT. SO WILL KEEP THE SLIGHT CHANCE OF
SHOWERS IN THE FORECAST FOR TUESDAY.
MARINE...
THE WINDS OVER THE LOCAL SOUTH FLORIDA WATERS WILL BE SOUTHERLY
THIS AFTERNOON INTO TONIGHT...BEFORE SWINGING TO A NORTHERLY
DIRECTION THURSDAY INTO FRIDAY. THE SPEEDS WILL ALSO INCREASE FROM
10 TO 15 KNOTS TONIGHT TO 15 TO 20 KNOTS THURSDAY AFTERNOON INTO
FRIDAY. THIS WILL ALLOW FOR THE ATLANTIC SEAS TO INCREASE FROM 2
TO 3 FEET TONIGHT UP TO AROUND 7 FEET BY THURSDAY NIGHT INTO
FRIDAY. THE GULF SIDE SEAS WILL REMAIN BELOW 6 FEET TONIGHT INTO
FRIDAY. SO A SCEC AND OR SCA WILL MORE LIKELY BE NEEDED BY
THURSDAY AFTERNOON INTO THURSDAY NIGHT FOR THE LOCAL WATERS OF
SOUTH FLORIDA.
FIRE WEATHER...
THE RELATIVE HUMIDITIES OVER SOUTH FLORIDA WILL REMAIN ABOVE THE
35 PERCENT CRITICAL VALUE FOR REST OF THE WEEK INTO THIS WEEKEND.
SO NO PROBLEMS ARE EXPECTED WITH THE FIRE WEATHER PRODUCTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 76 64 78 65 / 20 10 10 10
FORT LAUDERDALE 78 66 78 67 / 20 10 10 10
MIAMI 79 67 79 66 / 20 10 10 10
NAPLES 76 58 77 59 / 10 - - -
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...23/SK
AVIATION/RADAR...60/BD
AREA FORECAST DISCUSSION
NWS GOODLAND KS
201 AM MST THU DEC 13 2012
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 158 AM MST THU DEC 13 2012
04Z WATER VAPOR IMAGERY AND RAP ANALYSIS INDICATED LOW AMPLITUDE H5
RIDGE IN PLACE ACROSS THE REGION WITH STRONG TROUGH ALONG AND JUST
OF THE WEST COAST. THIS SYSTEM WILL PLAY A LARGE ROLE ON EXPECTED
WEATHER THROUGH THE START OF THE WEEKEND...AND IS STILL NOT TOTALLY
BEING SAMPLED BY UPPER AIR NETWORK. 00Z SOUNDINGS INDICATED A DRY
AND MUCH WARMER AIRMASS THAN 24 HOURS AGO...WITH STRONGEST WARMING
BETWEEN H8 AND H6. AT THE SFC...TROUGH AXIS WAS IN PLACE ALONG
ROUGHLY A KLBF TO KTRB LINE.
MAIN FORECAST CONCERNS WILL BE SKY COVER THIS MORNING AND TONIGHT
DUE TO GEMINID METEOR SHOWER AND PRECIPITATION POTENTIAL FRIDAY.
TODAY-TONIGHT...SHORT WAVE RIDGING WILL CONTINUE ACROSS THE AREA
THROUGH THE EVENING AND ALTHOUGH WEAK AMPLITUDE WILL NOT CREATE ANY
STRONG SUBSIDENCE DRY AND STABLE CONDITIONS EXPECTED SO ANY WEAK
ASCENT WILL NOT HAVE MUCH OF AN IMPACT ON SENSIBLE WEATHER. ALREADY
SEEING A LOT OF CIRRUS MOVING OVER THE AREA...WITH 80-90KT H3 WINDS
HELPING INDUCE CIRRUS DOWNSTREAM OF THE MOUNTAINS. GIVEN EXPECTED
FLOW ALOFT...EXPECT CLOUD COVER TO PERSIST THROUGH THE MORNING HOURS
WHICH WILL LIKELY INHIBIT THE VIEWING OF METEOR SHOWER IN SOME
LOCATIONS. SKIES WILL CLEAR DURING THE AFTERNOON AS FLOW ALOFT
BECOMES LESS PERPENDICULAR TO MOUNTAINS AND RRQ OF H3 JET STREAK
SHIFT TO THE NORTH AND EAST ACROSS SOUTH DAKOTA. WHILE CIRRUS WILL
LINGER ACROSS NORTHERN CWA TONIGHT...SHOULD BE A FEW PERIODS WHERE
CLOUDS CLEAR UP ALTHOUGH CLOUD COVER WILL BEGIN TO INCREASE RAPIDLY
FROM THE SOUTHWEST AFTER 2 AM MST (3 AM CST) AS NEXT SYSTEM
APPROACHES.
FRIDAY...MUCH MORE ACTIVE WEATHER IS EXPECTED ACROSS THE CWA ON
FRIDAY AS STRONG TROUGH BEGINS TO MOVE OVER THE AREA. MODELS HAVE
COME INTO MUCH BETTER AGREEMENT WITH TIMING OF FAIRLY PROGRESSIVE
TROUGH ACROSS THE PLAINS...ALTHOUGH LOOKING AT THE INDIVIDUAL
DYNAMIC TROP ANALYSIS FROM THE GFS AND NAM...AM A LITTLE CONCERNED
WITH GFS DEPICTING A MUCH LESS CONSOLIDATED PV ANOMALY WHICH OFTEN
TENDS TO HINDER WIDESPREAD PERSISTENT PRECIPITATION RATHER THAN HELP.
WHILE THE POSSIBILITY OF TROUGH COMING OUT IN PIECES LOWERS
CONFIDENCE SOMEWHAT...ENOUGH AGREEMENT BETWEEN OPERATIONAL MODELS TO
SUPPORT PROBABLY ONE OF THE BETTER CHANCES FOR PRECIP OVER THE PAST
MONTH AND BASED ON ALL FACTORS THINK 30-60 PROBABILITIES WARRANTED.
BEST CHANCES WILL BE ACROSS EASTERN CWA WHERE ISENTROPIC ANALYSIS
INDICATES STRONGEST MOISTURE TRANSPORT IN THIS AREA WITH A SECOND
MAXIMUM IN FORCING LOCATED TO NORTH OF SFC WARM FRONT IN NORTHWEST
CWA. DEPENDING ON HOW QUICKLY CLEARING OCCURS ONCE DRY SLOT
CIRCULATION BEGINS TO ENTER CWA COULD POSSIBLY SEE A SFC BASED
THUNDERSTORM ALONG DRY LINE IN SOUTHEASTERN ZONES AROUND SUNSET.
WHILE THERE IS SOME DATA SUGGESTING A CHANGE OVER TO SNOW IS
POSSIBLE IN THE WEST DURING THE AFTERNOON...AM GOING TO LEAN TOWARDS
A CONSENSUS OF AVAILABLE DATA AND HOLD OFF ON ANY COMPLETE CHANGE
OVER UNTIL AFTER 00Z.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 158 AM MST THU DEC 13 2012
FRIDAY NIGHT-SATURDAY NIGHT...EXPECT PRECIP CHANCES TO BE MAXIMIZED
RIGHT AROUND SUNSET ON FRIDAY NIGHT BEFORE PRECIP CHANCES BEGIN TO
END FROM SOUTHWEST TO NORTHEAST AS DOWNWARD MOTION INTENSIFIES
BEHIND DEPARTING TROUGH. AM A LITTLE CONCERNED ABOUT POTENTIAL FOR
ACCUMULATING SNOW ACROSS NORTHWEST CWA WITH POTENTIAL INSTABILITY
PRESENT AND PERSISTENT...NEARLY STATIONARY AREA OF LOW LEVEL
FRONTOGENESIS. HOWEVER...THIS AREA WOULD BE ONE OF THE FIRST AREAS
FOR FORCING TO DIMINISH AS UPPER LEVEL FLOW BECOMES SUBSIDENT AND
AFTER LOOKING AT PAST FEW ROUNDS OF ANALOG GUIDANCE...DO NOT THINK
PROBABILITY FOR MEANINGFUL SNOWFALL ACCUMULATIONS IS ALL THAT HIGH.
WINDS WILL LIKELY PICK UP INTO THE 20-30 MPH RANGE AS SYSTEM
DEPARTS...BUT EXPECT ANY POTENTIAL SNOW TO BE OVER WITH BEFORE WINDS
DEVELOP.
ON SATURDAY...STRONG DOWNWARD MOTION WILL BRING AN END TO THE
PRECIPITATION THREAT AND BRING SOME CLEARING TO THE AREA IN THE
MORNING...WITH CLOUDS BEGINNING TO INCREASE LATE IN THE AFTERNOON AS
A WEAK SHORT WAVE TROUGH APPROACHES. WHILE MODELS/ENSEMBLES
GENERALLY SUPPORT A PRECIPITATION THREAT...HAVE CONCERNS THAT A LOW
AMPLITUDE/TRANSIENT DISTURBANCE WILL PROVIDE ENOUGH FORCED ASCENT TO
SATURATE DRY LOWER LEVELS LEFT IN WAKE OF PREVIOUS SYSTEM AND WILL
KEEP POPS LIMITED TO 10-20 FOR THE EVENING PERIOD.
SUNDAY THROUGH WEDNESDAY...DETERMINISTIC AND ENSEMBLE OUTPUT
CONTINUE TO SHOW A LOT OF SPREAD THROUGH THE ENTIRE PERIOD.
HOWEVER...IN GENERAL THEY ARE SHOWING A FAST FLOW WITH MULTIPLE
EMBEDDED SHORTWAVE TROUGHS MOVING THROUGH THIS FLOW. FOR THE AREA
THIS IS NOT A FAVORABLE FLOW FOR PULLING IN SIGNIFICANT MOISTURE FOR
THESE SYSTEMS TO WORK WITH. BASED ON THAT...MODEL TRENDS IN THE LAST
24 HOURS...AND COLLABORATION...REMOVED WHAT WAS LEFT OF THE CHANCE
OF PRECIPITATION THAT THE CRH INIT GAVE ME FOR MONDAY. SO IT IS NOW DRY
THROUGH THIS PERIOD. OTHER THAN THAT...SAW NO NEED TO MAKE ANY
CHANGES TO THE GUIDANCE GIVEN TO ME.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1000 PM MST WED DEC 12 2012
VFR THROUGH THE PERIOD AT KGLD AND KMCK. SFC TROUGH TO MOVE
THROUGH IN THE NEXT FEW HOURS WITH W/NW AT 5-10KTS. WINDS BECOME
SOUTHEASTERLY BY 18Z-19Z THURSDAY MORNING AT 5-10KTS AHEAD OF A
SFC LOW EXPECTED TO BE IN SOUTHEAST COLORADO. ONLY HIGH LEVEL
CLOUDINESS EXPECTED...MAINLY THROUGH THE MORNING HOURS BEFORE
LIFTING NORTH OF THE AREA. ANOTHER BATCH MAY DEVELOP ALONG THE
FRONT RANGE THURSDAY AFTERNOON BRINGING ANOTHER INCREASE OVER OUR
TERMINALS DURING THAT PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JRM
LONG TERM...JRM/BULLER
AVIATION...99
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1247 AM EST THU DEC 13 2012
.UPDATE...
ISSUED AT 934 PM EST WED DEC 12 2012
STRONG S WINDS...WITH GUST AS HI AS 40 MPH AT PARENT BAY ON THE
SHORE OF SCHOOLCRAFT COUNTY UNDER 37KT WIND REPORTED ON THE 00Z GRB
RAOB AT 2K FT AGL...IN ADVANCE OF LO PRES IN MN HAS LIFTED
TEMPERATURES INTO THE 30S AT MOST LOCATIONS. SO TENDED TO BUMP UP
TEMPS A COUPLE OF DEGREES FM PREVIOUS FCST UNDER MID/HI OVC. WINDS WL
DIMINISH LATER...SO TEMPS MIGHT FALL AGAIN A BIT LATER.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 427 PM EST WED DEC 12 2012
WATER VAPOR LOOP AND RUC ANALYSIS SHOWS AN AMPLIFIED TROF OFF THE
WEST COAST WITH BROAD TROUGH CENTERED OVER HUDSON BAY DOMINATING
MUCH OF CANADA. AT THE SFC...A STATIONARY FRONT IS DRAPED OVER NORTH
DAKOTA...NRN MN INTO WRN UPR MI. A SHORTWAVE MOVING ACROSS SOUTHERN
CANADA ALONG WITH ITS ASSOC MID-LVL Q-VECT CONV AND 800 MB FGEN HAS
SUPPORTED AN AREA OF LIGHT SNOW THIS AFTERNOON OVER SRN MANITOBA AND
WRN ONTARIO.
TONIGHT...BEST FGEN FORCING AND Q-VECT CONV WITH SRN CANADA
SHORTWAVE IS FCST BY MODELS TO STAY MAINLY NORTH OF THE CWA TONIGHT.
THUS...IT ALSO MAKES SENSE THAT MODEL QPF ALSO STAYS MAINLY NORTH OF
THE AREA. MAINTAINED SLGT CHC POPS OVER THE TIP OF THE KEWEENAW AND
NRN LAKE SUPERIOR AS WEAK FORCING COULD BRUSH THESE AREAS WITH LIGHT
SNOW AND POSSIBLY DZ/FZDZ AS THERE IS A DRY LAYER ALOFT WHICH COULD
TEMPORARILY DISRUPT ICE CRYSTAL NUCLEATION. TEMPS SHOULDN`T DROP
MUCH TONIGHT UNDER CLOUDS AND INCREASING BLYR WINDS. EXPECT LOWS
FROM THE MID 20S INTERIOR WEST TO THE UPPER 20S/LOWER 30S
ELSEWHERE.
THURSDAY...A 120 KT 3H JET STREAK STREAMING EAST FROM THE CENTRAL
ROCKIES COMBINED WITH INCREASING 850-800 MB FGEN IN LEFT EXIT REGION
OF JET HAVE MOST MODELS SUPPORTING A NARROW BAND OF PCPN OVER THE
KEWEENAW PENINSULA LATE THU MORNING INTO EARLY AFTERNOON. CONTINUED
DRY LAYER AT MID-LVLS MAY DISRUPT ICE CRYSTAL NUCLEATION TO SUPPORT
SOME DZ/FZDZ MIXING IN WITH LIGHT SNOW. EXPECT ONLY A DUSTING OF
SNOW (HALF INCH OF LESS) OVER THE KEWEENAW AND MAINTAINED JUST HIGH
CHC POPS FOR NOW.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 427 PM EST WED DEC 12 2012
A MORE ACTIVE PATTERN LOOKS TO BE DEVELOPING BY THE END OF THE
WEEK...WITH THE MAIN FOCUS ON A POTENTIAL FOR MODERATE SNOWFALL
ACROSS MUCH OF THE AREA ON SATURDAY...AND THEN LIGHTER SNOW LASTING
INTO NEXT WEEK.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...THE LARGE SCALE FLOW WILL BE
GENERALLY ZONAL OVER THE GREAT LAKES REGION SOUTH OF A BROAD
MID-LEVEL LOW ACROSS HUDSON BAY AND NORTHERN QUEBEC. MEANWHILE...A
WEAK SHORTWAVE TROUGH WILL BE MOVING ESE ACROSS SOUTHERN MANITOBA
INTO WESTERN ONTARIO...AND A DEEP TROUGH WILL BE MOVING ONSHORE IN
CENTRAL AND SOUTHERN CA. THE DEEP WESTERN TROUGH WILL BE THE FOCUS
FOR SATURDAY ONWARD. BEFORE THEN...THE SHORTWAVE TROUGH IN SOUTHERN
CANADA WILL TRACK ACROSS WESTERN ONTARIO THURSDAY NIGHT...AND INTO
EASTERN ONTARIO BY FRIDAY AFTERNOON. INFLUENCE OF THIS TROUGH IS A
BIT WEAK ACROSS UPPER MI...AND MID-RANGE MODELS HAVE SOME
DISAGREEMENT ON PRECIP CHANCES. MID/UPPER FORCING IS NOT IMPRESSIVE
BY ANY MEANS UNTIL THE RIGHT ENTRANCE OF A 120KT UPPER JET CROSSES
THE CWA FRIDAY MORNING. BY THIS TIME...THE MID-LEVEL TROUGH WILL
ALMOST BE THROUGH THE AREA...WITH MID-LEVEL SUBSIDENCE/DRYING TAKING
HOLD. HOWEVER...LOW-LEVEL MOISTURE LINGERS...ESPECIALLY ACROSS THE
NORTHERN HALF OF THE CWA. WIND IS RATHER LIGHT AND VARIABLE THURSDAY
NIGHT THROUGH FRIDAY MORNING...BUT FAVORABLE DIRECTION IS BETWEEN N
AND E. WILL KEEP GENERAL SLIGHT CHANCE OF FZDZ NORTH...AND HAVE
EXPANDED IT SLIGHTLY TO ACCOUNT FOR TERRAIN EFFECTS.
OVERALL...EXPECT THE BEST CHANCE OF FZDZ TO BE LATE THURSDAY NIGHT
BEFORE DIMINISHING FRIDAY MORNING AS WINDS VEER TO THE SE.
BY FRIDAY EVENING...LOW LEVEL MOISTURE ADVECTING NORTHWARD AHEAD OF
THE NEXT SYSTEM WILL BRING ANOTHER POTENTIAL FOR FREEZING
DRIZZLE...THIS TIME ACROSS THE SOUTH-CENTRAL. SOUTHEAST WINDS OFF OF
LAKE MICHIGAN WILL ASSIST WITH THE MOISTURE SUPPLY...BUT THE
MOISTURE WILL BE SHALLOW (2KFT) AS A RESULT OF DRYING/SUBSIDENCE
UNDER A DEPARTING RIDGE. HAVE MENTIONED A SLIGHT CHANCE OF FREEZING
DRIZZLE IN THE HIGHER TERRAIN ACROSS THE SOUTH-CENTRAL...MAINLY
FOCUSED IN DICKINSON AND SOUTHERN MARQUETTE COUNTIES. INCREASING
CLOUD COVER COMBINED WITH STRENGTHENING WINDS SHOULD RESULT IN A
STEADY TEMP RISE THROUGHOUT THE NIGHT...WITH LOCATIONS ALONG LAKE
MICHIGAN REACHING ABOVE FREEZING BY DAY BREAK.
SATURDAY...RATHER COMPLICATED FORECAST CONCERNING THE POTENTIAL FOR
A STRONG LOW PRESSURE SYSTEM MOVING INTO THE AREA SATURDAY.
CONFIDENCE IS RUNNING LOW WITH THIS SYSTEM ATTM FOR SEVERAL REASONS.
FIRST...THE MID-LEVEL TROUGH IS STILL BARRELING SOUTHWARD ALONG THE
CA COAST THIS AFTERNOON...SO WHERE IT MAKES AN EASTWARD TURN WILL
HAVE SOME IMPLICATION ON OVERALL PLACEMENT AS IT MOVES OUT OF THE
LEE OF THE ROCKIES. ALL LONG TERM MODELS ARE IN GENERAL AGREEMENT OF
THE INITIAL PROGRESSION TAKING THE TROUGH THROUGH NORTHERN AZ. THIS
IS THE POINT WHERE THE MODELS DIVERGE...WITH THE EMERGENCE OF THE
LEE LOW RANGING FROM NEAR DENVER TO THE OK PANHANDLE. DIFFERENCES
CONTINUE TO GROW FROM THERE ON.
THE SECOND ISSUE COMES FROM THE TIMING OF ANOTHER SHORTWAVE TROUGH
MOVING ACROSS SOUTHERN CANADA AS EACH MODEL IS HANDLING THE STRENGTH
AND TIMING DIFFERENTLY. THE NAM IS THE STRONGEST/QUICKEST WITH THE
NORTHERN TROUGH...RESULTING IN AN INTERACTION WITH THE SOUTHERN
TROUGH MUCH FARTHER WEST ACROSS MN. MEANWHILE...THE ECMWF IS MUCH
MORE OPEN WITH THE TROUGH...AND INTERACTS WITH THE SOUTHERN TROUGH
OVER WI.
FINALLY...THE NAM AND GFS ARE BOTH PRODUCING AROUND 1 INCH OF LIQUID
PRECIP ACROSS IL ON SATURDAY...WHICH COULD RESULT IN A LACK OF
MOISTURE AVAILABILITY THIS FAR NORTH.
OVERALL THINKING IS THAT THE WESTWARD TRENDS OF THE MODELS ARE
BELIEVABLE...ESPECIALLY AS THE GFS COMES INTO LINE WITH THE MORE
CONSISTENT ECMWF. THEREFORE...A BLEND OF THOSE TWO MODELS WAS USED
FOR THIS SYSTEM. THE TWO TRACK THE SFC LOW THROUGH SOUTHERN WI LATE
SATURDAY AFTERNOON...AND INTO NORTHERN LOWER MI BY SUNDAY MORNING.
EVEN THOUGH H8 TEMPS CREEP ABOVE FREEZING AHEAD OF THE SYSTEM ON
SATURDAY...DRY AIR UNDER THE DEPARTING RIDGE WILL KEEP WET BULB
TEMPS BELOW FREEZING THROUGHOUT THE COLUMN. THERMAL PROFILES SUGGEST
A VERY WET SNOWFALL FOR THE CWA...WITH RAIN MIXING IN ACROSS THE
SOUTH CENTRAL AND EAST NEAR LAKE MICHIGAN. THOUGH THERE ARE SO MANY
DISCREPANCIES AMONG THE MODELS...THERE IS FAIRLY GOOD AGREEMENT THAT
A SHIELD OF MODERATE SNOW WILL MOVE NORTHEASTWARD THROUGH THE
CWA...BEGINNING SATURDAY MORNING NEAR THE MI/WI BORDER...AND
SATURDAY AFTERNOON ALONG LAKE SUPERIOR. PINPOINTING ANY AREAS FOR
ENHANCED SNOWFALL ATTM IS QUITE DIFFICULT...BUT THERE IS A STRONG
SIGNAL OF A H8-H7 FRONTOGENESIS BAND JUST NORTH OF THE LEFT EXIT OF
THE UPPER JET...WHEREVER THOSE FEATURES END UP.
NOT LOOKING LIKE WE WILL REACH WARNING CRITERIA (6IN/12HR)
SNOWFALL...BUT SNOW COULD ACCUMULATE QUICKLY AT TIMES ON SATURDAY.
GIVEN THE WATER CONTENT OF THE SNOW...THINGS COULD GET SLOPPY ACROSS
THE CWA.
SUNDAY THROUGH WEDNESDAY...THE FORECAST BECOMES MUDDLED BY THE END
OF THE WEEKEND AS THE MID-LEVEL LOW RESPONSIBLE FOR SATURDAYS SYSTEM
BECOMES WRAPPED UP ACROSS ONTARIO. THIS WILL PUT UPPER MI IN WEAK
NORTH TO NORTHWEST FLOW THROUGH MUCH OF THE REMAINDER OF THE PERIOD.
THE MAIN RESERVOIR OF COLD AIR IS CURRENTLY WELL TO THE NORTH ACROSS
THE ARCTIC AND SIBERIA...AND NOT REALLY A MAJOR FACTOR FOR LAKE
ENHANCEMENT/LAKE EFFECT OVER THE NEXT WEEK. THE COLDEST H8 AIR
BEHIND THE SYSTEM WILL MOVE ACROSS LAKE SUPERIOR SUNDAY NIGHT. EVEN
THEN...TEMPS ARE STILL ONLY AS LOW AS -10C. ALSO...INVERSION LEVELS
ARE ONLY ABOUT 4-5KFT FOR MUCH OF THE PERIOD. THE EXPECTATION IS
THAT THERE WILL BE INTERMITTENT SNOW SHOWERS...MAINLY NEAR LAKE
SUPERIOR...INTO THE MIDDLE OF NEXT WEEK. ACCUMULATIONS WILL BE LIGHT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1243 AM EST THU DEC 13 2012
WITH SW FLOW OF DRY AIR TO THE S OF WARM FNT OVER NRN LK SUP...
EXPECT VFR CONDITIONS TO PREDOMINATE THRU SUNRISE. THERE WL BE SOME
LLWS OR GUSTY WINDS AT ALL 3 SITES FOR THE FIRST COUPLE HRS AFTER
TAF ISSUANCE UNTIL LLJ PASSES FARTHER TO THE E. THEN A COLD FNT WL
PRESS SEWD THRU THE UPR LKS LATER TODAY. WITH RELATIVELY SHALLOW
INFUSION OF COLDER/MOISTER AIR BEHIND THE FROPA...CONDITIONS ARE
LIKELY TO FALL TO MVFR FIRST AT CMX BY NOON...AT IWD BY MID
AFTN...AND THEN AT SAW EARLY IN THE EVNG. BEST CHC FOR SOME
-SN/-FZDZ AND IFR CONDITIONS WL BE AT CMX/IWD WITH A BIT OF AN
UPSLOPE WNW WIND BEHIND THE FROPA.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 934 PM EST WED DEC 12 2012
UPDATE FOR 10 PM LAKE ISSUANCE...OPTED TO ISSUE GALE WARNING FOR THE
2 EAST ZONES GIVEN SHIP OB OF GUST UP TO 41 KTS AND 01Z CARIBOU
ISLAND REPORT OF 33 KT GUST. THE 00Z GREEN BAY WI RAOB SHOWED A 37KT
WIND AT 2K FT AGL...AND SUSPECT THIS HIER MOMENTUM WILL IMPACT THE E
PART OF LK SUP TO THE S OF PRES FALL CENTER THAT IS FORECAST TO DRIFT
ACROSS THE N PORTIONS OF THE LK THRU EARLY THU MORNING. RATHER
UNSTABLE TEMP PROFILE ALSO SHOULD SUPPORT MIXING OF THE HIER WINDS.
EXPECT SOUTH WINDS TO INCREASE OVER MOST OF LK SUPERIOR LATE THIS
AFTN AND ESPECIALLY TONIGHT. GUSTS TO GALES POSSIBLE EAST...BUT NOT
FREQUENT/STRONG ENOUGH TO ISSUE GALE WARNING. WINDS DIMINISH
STEADILY BLO 20 KTS LATER THURSDAY INTO THURSDAY NIGHT AS A WEAK
TROUGH CROSSES THE LAKE. WINDS STAY BLO 20 KTS THROUGH FRIDAY NIGHT
AS PRESSURE GRADIENT IS WEAK.
A LOW PRESSURE SYSTEM DEVELOPING IN THE PLAINS STILL ON TRACK TO
PUSH INTO WESTERN GREAT LAKES LATE SATURDAY INTO SUNDAY WHILE HIGH
PRESSURE MOVES ACROSS NEW ENGLAND. WINDS SHOULD INCREASE FROM THE
EAST TO 30 KTS LATE SATURDAY OVER LAKE SUPERIOR. EXACT TRACK AND
DEPTH OF SFC LOW REMAINS UNCERTAIN THOUGH SO KEPT WINDS BELOW GALE
IN THIS FORECAST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING UNTIL 4 AM EST EARLY THIS MORNING FOR LSZ266-267.
LAKE MICHIGAN...
GALE WARNING UNTIL 7 AM EST THIS MORNING FOR LMZ248-250.
GALE WARNING UNTIL 5 AM EST EARLY THIS MORNING FOR LMZ221.
&&
$$
UPDATE...KC
SHORT TERM...VOSS
LONG TERM...TK
AVIATION...KC
MARINE...VOSS/KC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
328 AM CST THU DEC 13 2012
.SHORT TERM...TODAY THROUGH FRIDAY...
THE HIGHLIGHT OF THE SHORT TERM IS PERSISTENT STRATUS AND ITS
IMPACT ON TEMPERATURES.
WIDESPREAD STRATUS IS IN PLACE ACROSS NORTH DAKOTA...MUCH OF
EASTERN MONTANA AND INTO SASKATCHEWAN AND ALBERTA. WITH A WEAK LOW
LEVEL WIND FIELD WITH WEAK WARM AIR ADVECTION REINFORCING THE
INVERSION TO TRAP THE STRATUS...EXPECT THE LOW LEVEL CLOUD COVER
TO LAST THROUGH AT LEAST TOMORROW MORNING...WITH THE LATEST RUNS
OF THE HRRR AND RAP KEEPING THE STRATUS ACROSS THE AREA THROUGH
THEIR ENTIRE VALID PERIODS. AS A RESULT...TEMPERATURE RECOVERY
THROUGH THE DAY WILL BE WEAK. MOST PLACES ARE ONLY EXPECTED TO RECOVER
ABOUT 5 DEGREES OR SO FROM MORNING LOWS...WITH HIGHS IN THE SINGLE
DIGITS NORTH TO THE UPPER 20S FAR SOUTHWEST. DID ADD FLURRIES TO
THE ENTIRE AREA THROUGH TODAY UNDER THE STRATUS...WITH A MENTION
OF MORNING FOG ACROSS THE SOUTHWEST IN WEAK UPSLOPE FLOW.
FOR TONIGHT...WITH STRATUS IN PLACE TEMPERATURES DECLINES WILL
ALSO BE MINIMAL...AGAIN ABOUT 5 DEGREES AT THE MOST FOR MUCH OF
THE AREA. DID NOT ADD FOG...HOWEVER...THIS WILL HAVE TO BE
MONITORED AS A BUILD DOWN OF THE STRATUS MAY BE POSSIBLE.
THE FORECAST FOR FRIDAY IS A BIT UNCERTAIN AS THE MODELS DO NOT
HAVE THE BEST HANDLE ON THE STRATUS EVOLUTION FOR TODAY. DID TRY
TO HOLD THE STRATUS THROUGH THE MORNING HOURS ON
FRIDAY...HOWEVER...WOULD NOT BE SURPRISED IF THE STRATUS HOLDS
LONGER UNDER AN INVERSION THAT IS REINFORCED BY STRONGER WARM
AIR ADVECTION. THUS...IMPACTS ON THERMAL FIELDS FROM SKY COVER ARE
SIGNIFICANT FOR FRIDAY.
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
BROAD CYCLONIC FLOW OVER CONUS WITH BELT OF STRONGEST
WESTERLIES WELL SOUTH OF THE REGION. WESTERN AND CENTRAL NORTH
DAKOTA GENERALLY CUTOFF FROM GULF MOISTURE WITH MAJOR SYSTEMS
SHUNTED FAR TO THE SOUTH. TEMPERATURES ARE MODERATE SLIGHTLY BELOW
NORMAL WITH NO MAJOR COLD OUTBREAKS. NO PRECIPITATION IS GENERATED
BY A BLEND OF MODEL SOLUTIONS THOUGH NEAR THE END OF THE EXTENDED
ECMWF BRINGS MORE SIGNIFICANT SYSTEM TO THE NORTHERN PLAINS WHICH IS
NOT SEEN IN THE GEFS.
&&
.AVIATION...
MOIST AIRMASS TRAPPED BENEATH DOME OF HIGH PRESSURE WILL
BRING MVFR TO IFR CEILINGS TO WESTERN AND CENTRAL NORTH DAKOTA. SOME
LINGERING FLURRIES AND FOG ARE POSSIBLE IN THE EAST AND IN THE
SOUTHWEST WHERE GREATEST UPSLOPE FLOW IS OCCURRING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...AYD
LONG TERM/AVIATION...HW
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
1226 AM CST THU DEC 13 2012
.UPDATE...BAND OF SNOW HAS NOW SET UP ALONG I-94 IN NORTH DAKOTA
AND EASTWARD INTO MINNESOTA. BISMARCK RECEIVED ABOUT 3 INCHES THIS
EVENING...AND ANTICIPATE 1-3 INCHES ALONG THIS NARROW BAND BY
MORNING. 05Z RAP INDICATES THE BAND WILL HOLD TOGETHER THROUGH THE
FA (ALTHOUGH ITS LOCATION IS TOO FAR SOUTH) WITH UP TO 3 INCHES
POSSIBLE.
&&
.AVIATION...EXPECT MVFR CIGS THROUGH THE PERIOD WITH SOME LIGHT
SNOW POSSIBLE LATER TONIGHT INTO THU. WINDS SHOULD BE NORTHERLY
WITH HIGH PRESSURE BUILDING IN FROM CANADA. VSBYS COULD LOWER INTO
IFR RANGE NEAR KFAR FROM A BETTER DEFINED SNOW BAND IF IT
DEVELOPS...SO WE WILL MONITOR THIS POTENTIAL.
&&
.PREV DISCUSSION... /ISSUED 754 PM CST WED DEC 12 2012/
DISCUSSION...
THE MAIN CHALLENGE OVERNIGHT WILL BE SNOW POTENTIAL IN A FAIRLY
NARROW BAND ALONG THE I 94 CORRIDOR. A MID LEVEL BAND OF FGEN IN
THE 850-700MB LEVEL IS SETTING UP FROM KDIK-KBIS THIS
EVENING...AND EXPECT THIS TO PROGRESS TO THE E/NE OVERNIGHT. THE
GFS HAD THE BEST HANDLE ON THIS...AND THE RAP SLOWLY WEAKENS THIS
SNOW OVERNIGHT WITH SFC HIGH BUILDING IN. THE INHERITED POPS
REALLY LOOK GOOD WITH THE POTENTIAL FOR UP TO AN INCH OF SNOW IN A
NARROW BAND...SO WILL MAINTAIN THIS POTENTIAL. THESE SNOW BANDS
SOMETIMES DEVELOP A BIT MORE THAN MODELS INDICATE...SO WILL
CONTINUE TO MONITOR...BUT GRIDS ARE IN GOOD SHAPE. WILL RAISE
OVERNIGHT MINIMUMS IN THE NORTH AND THE SOUTH...WITH PLENTY OF
CLOUDS AND COOLING RELYING ON LOW LEVEL CAA BEHIND THE COLD FRONT.
PREV DISCUSSION... /ISSUED 230 PM CST WED DEC 12 2012/
DISCUSSION...FORECAST CHALLENGE CONCERNS TEMPERATURES AND SNOW
CHANCES. MODELS SHOWING SOME MINOR DIFFERENCES WITH SNOW BAND LATE
TONIGHT INTO TOMORROW AND WILL CONTINUE WITH A BLEND.
NEXT WAVE PUSHING INTO WESTERN WYO IN MID LEVEL ZONAL FLOW AND WILL
IMPACT THE REGION LATE TONIGHT INTO THURSDAY. MAIN JET AXIS THROUGH
THE CENTRAL PLAINS AND UPPER SUPPORT AT THIS TIME LOOKS RELATIVELY
WEAK. THERE IS A BAND OF LOWER CONDENSATION PRESSURE DEFICIT/MODEST
ISENTROPIC LIFT AND FRONTOGENETIC FORCING GENERALLY BETWEEN HIGHWAY
2 AND I 94 FROM MIDNIGHT ON. MODELS HAVE BEEN RELATIVELY CONSISTENT
WITH THIS AND WILL INCREASE POPS. AT THIS POINT WITH RELATIVELY WEAK
ABOVE MENTIONED FORCING MECHANISMS FEEL GENERAL SNOW AMOUNTS IN THE
1-2 INCH RANGE LOOK REASONABLE AT THIS TIME INTO MID DAY THURSDAY.
BAROCLINIC ZONE SAG SLOWLY SOUTH TONIGHT HOWEVER EXTENSIVE CLOUD
LAYER SHOULD LIMIT DROP TONIGHT. COULD STILL SEE A FAIRLY
RESPECTABLE TEMPERATURE CONTRAST ACROSS THE REGION WITH COLDEST
TEMPERATURES ACROSS FAR NORTH WHERE TEMPERATURES CURRENTLY BLO
ZERO.
MODELS DIFFER ON DURATION OF -SN ALONG NARROW CORRIDOR THURSDAY
HOWEVER WOULD EXPECT BAND TO SHIFT EAST WITH WAVE REPRESENTED BY
NAM/GFS 290K ISENTROPIC SURFACE AND WILL TIME POPS ACCORDINGLY. LOW
LEVEL RH REMAINS IN PLACE SO CLOUD TRENDS WITH WAVE PASSAGE IN
QUESTION. WITH LIGHT MIXING AS SURFACE HIGH BUILDS IN TEMPERATURE
RECOVER WILL BE MINOR AND HAVE TRIMMED BACK ON MAXIMUM VALUES.
SHOULD BE QUIET REMAINDER OF WORK WEEK WITH SLIGHTLY MODERATING
THERMAL COLUMN. LOW LEVEL RH REMAINS ACROSS FA SO CLOUDS REMAIN A
QUESTION AND THIS TIME OF YEAR A MAJOR PLAYER WITH TEMPERATURES.
GEM A SIGNIFICANT OUTLIER WITH NORTHWARD EXTEND OF QPF FRIDAY NIGHT
AND WILL BE DISCARDED. NAM/ECMWF STILL CLIP FAR SE-E FA SAT AND WILL
MAKE SOME MINOR POP ADJUSTMENTS.
LONG TERM... /SAT NIGHT THROUGH WED/
LONG TERM MODELS IN REASONABLE AGREEMENT EARLY IN THE PERIOD...BUT
DIVERGE SIGNIFICANTLY FOR EARLY NEXT WEEK. STRONG LOW PRESSURE
SYSTEM EXPECTED TO LIFT OUT OF THE CENTRAL PLAINS AND INTO THE GREAT
LAKES OVER THE WEEKENDS...WITH WRAP AROUND SNOW POSSIBLY IMPACTING
MY EASTERN ZONES SAT NIGHT AND SUN. 12Z ECWMF MORE IN LINE WITH THE
00Z/12Z GFS...WHICH PULLS PRECIP OUT OF THE AREA BY NOON SUN. PREV
ECMWF KEPT LINGERING PRECIP IN THE EAST THROUGH MONDAY. GFS THEN
SIGNIFICANTLY DIVERGES FROM ECWMF WITH A CLIPPER LIKE SYSTEM MOVING
ACROSS NORTHERN TIER MON NIGHT INTO TUE. CURRENT ALLBLEND SOLUTION
CONTINUES TO KEEP A DRY FCST IN FOR TUE...BUT GFS SOLUTION WOULD
CERTAINLY BRING SNOW SNOWFALL ACROSS OUR NORTHERN ZONES MON NIGHT
AND TUE. DUE TO LOW CONFIDENCE...WILL GO WITH DRY SOLUTION.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
TG
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
411 AM PST THU DEC 13 2012
.SHORT TERM DISCUSSION...
IR SATELLITE IMAGERY SHOWS UPPER LOW NOW CENTERED ROUGHLY OVER THE
SIERRA FOOTHILLS THIS MORNING. SHORTWAVE DISTURBANCES ROTATING
AROUND THIS LOW BROUGHT A FEW SHOWERS OVER THE SIERRA AND FOOTHILLS
OVER NIGHT WITH SNOW LEVELS DROPPING SNOW DOWN TO THE 2500 FOOT
LEVEL. ONE DISTURBANCE ROTATING AROUND THE BASE OF THE LOW BROUGHT A
FEW SHOWERS TO THE SOUTHERN SACRAMENTO VALLEY. THESE SHOWERS SHOULD
DISSIPATE WITHIN THE NEXT FEW HOURS. OVERALL...CWA WILL REMAIN UNDER
PARTLY CLOUDY SKIES TODAY. THERE HAS BEEN ENOUGH CLEARING IN SOME
AREAS FOR SOME AREAS OF MORNING FOG. SOME RAP AROUND MOISTURE COULD
KEEP A FEW SHOWERS GOING OVER THE NORTHERN SIERRA THROUGH THE DAY.
THE UPPER LOW AND ASSOCIATED TROUGH IS FORECAST TO SHIFT EAST OF THE
STATE BY THIS EVENING WITH NORTHERLY FLOW DEVELOPING OVER THE
NORTHERN HALF OF THE STATE. THURSDAY NIGHT LOOKS DRY UNDER
SMALL SCALE RIDGING. A PACIFIC FRONT NOW IN THE GULF OF ALASKA WILL
DROP QUICKLY TOWARDS THE NORCAL COAST THURSDAY NIGHT. MODELS ARE
STILL INDICATING THAT THIS SYSTEM WILL SPLIT AS IT MOVES INLAND.
MODELS VARY ON THE EXACT PATH OF THE SOUTHERN PORTION OF THIS SYSTEM
BUT IN GENERAL THIS LOW DROPS SOUTHWARD. MODELS VARY ON AMOUNT OF
PRECIP OVER THE FORECAST AREA WITH ECMWF KEEPING MOST PRECIP OFF THE
COAST WHILE GFS AND GEM BRING LARGER THREAT OF PRECIP INLAND. EITHER
WAY...PRECIP AMOUNTS REMAIN ON THE LIGHT SIDE. BRIEF RIDGING FRIDAY
NIGHT WITH A RE-CONSOLIDATION OF THE PACIFIC STORM TRACK BACK INTO
THE PACIFIC NORTHWEST BY SATURDAY AFTERNOON. THEREFORE...LOOKS LIKE
FIRST PORTION OF UPCOMING WEEKEND WILL BE MAINLY DRY OVER THE REGION
WITH A RETURN TO A WETTER PERIOD FOR THE SECOND PORTION AND GOING
INTO NEXT WEEK. QPF VALUES FOR THIS SYSTEM LOOK A LITTLE LARGER THAN
FOR THE PREVIOUS COUPLE BUT STILL FAIRLY LOW COMPARED TO THE LARGER
STORMS EARLIER THIS MONTH.
.EXTENDED DISCUSSION (MONDAY THROUGH THURSDAY)
UNSETTLE PATTERN PERSISTS DURING THE EXTENDED FORECAST WHERE
WEATHER WILL YO-YO BETWEEN PERIODS OF RAIN/SNOW AND DRY
CONDITIONS. TIMING OF THE WET PERIODS HAS NOT BEEN CONSISTENT IN
THE MODEL RUNS. THE MOST RECENT GFS & ECMWF RUNS INDICATE A
WAVE ON MONDAY INTO TUESDAY...DRIER ON WEDNESDAY WITH LINGERING
ISOLATED SHOWERS POSSIBLE. THEN THE NEXT WAVE ARRIVING LATE
WED/EARLY THURSDAY. HAVE KEPT A SLIGHT CHANCE TO CHANCE OF
PRECIPITATION THROUGHOUT THE EXTENDED FORECAST. SNOW LEVELS WILL
BE FAIRLY LOW AS COLD AIR ALOFT STREAMS OVER THE REGION...
GENERALLY BETWEEN 2000-4000 FEET. JBB
&&
.AVIATION...
PARTLY CLOUDY SKIES CONTINUE DURING THE MORNING HOURS WITH SCT-
BKN-OVC MID TO HIGH LEVEL CLOUDS. NEAR THE SURFACE...SOME FOG/LOW LEVEL
STRATUS HAS BEEN DEVELOPING IN PORTIONS OF THE NORTHERN SAN
JOAQUIN VALLEY AND COULD SPREAD INTO THE SOUTHERN SACRAMENTO
VALLEY WITH VSBYS RANGING LIFR UP TO MVFR THROUGH ABOUT 16Z THIS MORNING.
LIGHT WINDS OVER THE AREA DURING THE NEXT 24 HRS.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
1050 AM EST Thu Dec 13 2012
.NEAR TERM [Through Tonight]...
15z CONUS NAM/Regional RAP analysis depict the mid-level shortwave
trough axis positioned north to south along the Mid-Atlantic
states. Locally, subsidence on the back side of the wave has
resulted in very dry air spreading through the upper/middle levels
of the atmosphere. At the surface, northeasterly flow between a
developing low in the western Atlantic, and high pressure spanning
the entire eastern third of the country, is providing a continuous
low level moisture feed to the Southeast. As a result, low clouds
currently hold a firm grip on the Tri-State region. This mornings
KTAE sounding indicates that the saturated layer is about 3000 ft
deep. With the subsidence inversion atop the moist layer, and very
little insolation due to the thick, continuous nature of the
stratus deck, it is likely that the clouds will stick around for
much, if not all of the day. This is especially true for the
Tallahassee and Valdosta areas, whereas communities near Dothan,
Albany, and Panama City may break out along the edge of the cloud
deck later today. It is likely that the drizzle experienced this
morning has ended for most locations, and the main impact of the
cloud cover will be to keep chilly temperatures in the forecast
all afternoon. Expect all locations throughout the Tri-State
region to remain below 60 degrees today, with areas under the
thickest cloud cover hovering in the lower 50s.
At this point, all indications are that the low clouds will linger
through the overnight hours tonight.
&&
.SHORT TERM [Friday Through Saturday]...
Deep layer ridging firmly in place Friday with seasonal afternoon
temps and dry conditions. Temps won`t be as cold Friday night as
winds swing around to the east and mid to upper level clouds spread
in from the west ahead of the next low pressure system. Saturday
will be a day of transition as the upper ridge flattens and the
surface ridge weakens allowing a cold front to edge closer to our
CWA. Clouds will further increase throughout the CWA but only a
slight chance for rain across SE Alabama in the afternoon.
Temperatures will elevate above seasonal levels as winds shifting to
the southeast and south.
&&
.LONG TERM [Saturday Night through next Thursday]...
We continue to see model to model and run to run inconsistencies
with respect to the evolution of the upper level flow pattern and
associated frontal systems through the mid/long range periods.
Confidence in this part of the forecast remains below average. We
generally used a blend of HPC guidance and gridded MOS for most
fields. Details will need to be resolved later, but the general
trend shows a retreating ridge at the start of the period which
brings another day of warm temps on Sunday. A frontal system will
approach from the west. Chance PoPs (30-50%) were used with
highest northwest. As short wave energy moves from the Southern
Plains out into the Mid South, a wave develops on the front and
highest PoPs (40-60%) are realized on Monday as the front moves
through. We generally followed the GFS solution after that with
high pressure building eastward along the Gulf Coast in the wake
of the front. Since this air mass is of Pacific origin, temps will
generally be close to average behind the cold front. The next
frontal system is progged to approach on Thursday.
It should be noted that the 12/12Z Euro was much less progressive
and showed a deepening trough with a massive coastal low bombing
along the Southeast U.S. coast on Tuesday. The latest 00Z Euro is
closer to our preferred solution, at least in terms of sensible
weather locally.
&&
.AVIATION [Beginning 16Z Thursday]...
Low end MVFR to high end IFR ceilings prevail at all terminals as
of 16z. It is possible that KABY and KDHN will scatter out to VFR
conditions later this afternoon. Elsewhere, MVFR ceilings are
expected for the remainder of the day. Low clouds will likely
linger overnight, and updated restrictions will be re-introduced
with the 18z TAF.
&&
.MARINE...
Cautionary conditions over the coastal waters should gradually drop
below these levels later this afternoon as the pressure gradient
slowly weakens. Then, we expect winds and seas to remain below
headline criteria through the weekend as winds gradually veer from
northeast to southwest. Winds may reach advisory levels Sunday Night
into Monday with the approach and passage of a strong cold front.
&&
.FIRE WEATHER...
Relative humidity is expected to remain above critical levels
through much of the next week.
&&
.HYDROLOGY...
No river rises of any significance are expected at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 54 39 66 46 71 / 10 0 0 0 10
Panama City 58 43 65 52 69 / 10 0 0 0 10
Dothan 58 38 63 46 68 / 10 0 0 0 10
Albany 56 36 64 44 68 / 10 0 0 0 10
Valdosta 53 40 65 45 71 / 0 0 0 0 10
Cross City 56 42 71 48 76 / 0 0 0 0 10
Apalachicola 58 43 64 51 69 / 10 0 0 0 10
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Harrigan
SHORT TERM...Barry
LONG TERM...Wool
AVIATION...Harrigan
MARINE...Gould
FIRE WEATHER...Wool
HYDROLOGY...Harrigan
AREA FORECAST DISCUSSION
NWS GOODLAND KS
418 AM MST THU DEC 13 2012
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 158 AM MST THU DEC 13 2012
04Z WATER VAPOR IMAGERY AND RAP ANALYSIS INDICATED LOW AMPLITUDE H5
RIDGE IN PLACE ACROSS THE REGION WITH STRONG TROUGH ALONG AND JUST
OF THE WEST COAST. THIS SYSTEM WILL PLAY A LARGE ROLE ON EXPECTED
WEATHER THROUGH THE START OF THE WEEKEND...AND IS STILL NOT TOTALLY
BEING SAMPLED BY UPPER AIR NETWORK. 00Z SOUNDINGS INDICATED A DRY
AND MUCH WARMER AIRMASS THAN 24 HOURS AGO...WITH STRONGEST WARMING
BETWEEN H8 AND H6. AT THE SFC...TROUGH AXIS WAS IN PLACE ALONG
ROUGHLY A KLBF TO KTRB LINE.
MAIN FORECAST CONCERNS WILL BE SKY COVER THIS MORNING AND TONIGHT
DUE TO GEMINID METEOR SHOWER AND PRECIPITATION POTENTIAL FRIDAY.
TODAY-TONIGHT...SHORT WAVE RIDGING WILL CONTINUE ACROSS THE AREA
THROUGH THE EVENING AND ALTHOUGH WEAK AMPLITUDE WILL NOT CREATE ANY
STRONG SUBSIDENCE DRY AND STABLE CONDITIONS EXPECTED SO ANY WEAK
ASCENT WILL NOT HAVE MUCH OF AN IMPACT ON SENSIBLE WEATHER. ALREADY
SEEING A LOT OF CIRRUS MOVING OVER THE AREA...WITH 80-90KT H3 WINDS
HELPING INDUCE CIRRUS DOWNSTREAM OF THE MOUNTAINS. GIVEN EXPECTED
FLOW ALOFT...EXPECT CLOUD COVER TO PERSIST THROUGH THE MORNING HOURS
WHICH WILL LIKELY INHIBIT THE VIEWING OF METEOR SHOWER IN SOME
LOCATIONS. SKIES WILL CLEAR DURING THE AFTERNOON AS FLOW ALOFT
BECOMES LESS PERPENDICULAR TO MOUNTAINS AND RRQ OF H3 JET STREAK
SHIFT TO THE NORTH AND EAST ACROSS SOUTH DAKOTA. WHILE CIRRUS WILL
LINGER ACROSS NORTHERN CWA TONIGHT...SHOULD BE A FEW PERIODS WHERE
CLOUDS CLEAR UP ALTHOUGH CLOUD COVER WILL BEGIN TO INCREASE RAPIDLY
FROM THE SOUTHWEST AFTER 2 AM MST (3 AM CST) AS NEXT SYSTEM
APPROACHES.
FRIDAY...MUCH MORE ACTIVE WEATHER IS EXPECTED ACROSS THE CWA ON
FRIDAY AS STRONG TROUGH BEGINS TO MOVE OVER THE AREA. MODELS HAVE
COME INTO MUCH BETTER AGREEMENT WITH TIMING OF FAIRLY PROGRESSIVE
TROUGH ACROSS THE PLAINS...ALTHOUGH LOOKING AT THE INDIVIDUAL
DYNAMIC TROP ANALYSIS FROM THE GFS AND NAM...AM A LITTLE CONCERNED
WITH GFS DEPICTING A MUCH LESS CONSOLIDATED PV ANOMALY WHICH OFTEN
TENDS TO HINDER WIDESPREAD PERSISTENT PRECIPITATION RATHER THAN HELP.
WHILE THE POSSIBILITY OF TROUGH COMING OUT IN PIECES LOWERS
CONFIDENCE SOMEWHAT...ENOUGH AGREEMENT BETWEEN OPERATIONAL MODELS TO
SUPPORT PROBABLY ONE OF THE BETTER CHANCES FOR PRECIP OVER THE PAST
MONTH AND BASED ON ALL FACTORS THINK 30-60 PROBABILITIES WARRANTED.
BEST CHANCES WILL BE ACROSS EASTERN CWA WHERE ISENTROPIC ANALYSIS
INDICATES STRONGEST MOISTURE TRANSPORT IN THIS AREA WITH A SECOND
MAXIMUM IN FORCING LOCATED TO NORTH OF SFC WARM FRONT IN NORTHWEST
CWA. DEPENDING ON HOW QUICKLY CLEARING OCCURS ONCE DRY SLOT
CIRCULATION BEGINS TO ENTER CWA COULD POSSIBLY SEE A SFC BASED
THUNDERSTORM ALONG DRY LINE IN SOUTHEASTERN ZONES AROUND SUNSET.
WHILE THERE IS SOME DATA SUGGESTING A CHANGE OVER TO SNOW IS
POSSIBLE IN THE WEST DURING THE AFTERNOON...AM GOING TO LEAN TOWARDS
A CONSENSUS OF AVAILABLE DATA AND HOLD OFF ON ANY COMPLETE CHANGE
OVER UNTIL AFTER 00Z.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 158 AM MST THU DEC 13 2012
FRIDAY NIGHT-SATURDAY NIGHT...EXPECT PRECIP CHANCES TO BE MAXIMIZED
RIGHT AROUND SUNSET ON FRIDAY NIGHT BEFORE PRECIP CHANCES BEGIN TO
END FROM SOUTHWEST TO NORTHEAST AS DOWNWARD MOTION INTENSIFIES
BEHIND DEPARTING TROUGH. AM A LITTLE CONCERNED ABOUT POTENTIAL FOR
ACCUMULATING SNOW ACROSS NORTHWEST CWA WITH POTENTIAL INSTABILITY
PRESENT AND PERSISTENT...NEARLY STATIONARY AREA OF LOW LEVEL
FRONTOGENESIS. HOWEVER...THIS AREA WOULD BE ONE OF THE FIRST AREAS
FOR FORCING TO DIMINISH AS UPPER LEVEL FLOW BECOMES SUBSIDENT AND
AFTER LOOKING AT PAST FEW ROUNDS OF ANALOG GUIDANCE...DO NOT THINK
PROBABILITY FOR MEANINGFUL SNOWFALL ACCUMULATIONS IS ALL THAT HIGH.
WINDS WILL LIKELY PICK UP INTO THE 20-30 MPH RANGE AS SYSTEM
DEPARTS...BUT EXPECT ANY POTENTIAL SNOW TO BE OVER WITH BEFORE WINDS
DEVELOP.
ON SATURDAY...STRONG DOWNWARD MOTION WILL BRING AN END TO THE
PRECIPITATION THREAT AND BRING SOME CLEARING TO THE AREA IN THE
MORNING...WITH CLOUDS BEGINNING TO INCREASE LATE IN THE AFTERNOON AS
A WEAK SHORT WAVE TROUGH APPROACHES. WHILE MODELS/ENSEMBLES
GENERALLY SUPPORT A PRECIPITATION THREAT...HAVE CONCERNS THAT A LOW
AMPLITUDE/TRANSIENT DISTURBANCE WILL PROVIDE ENOUGH FORCED ASCENT TO
SATURATE DRY LOWER LEVELS LEFT IN WAKE OF PREVIOUS SYSTEM AND WILL
KEEP POPS LIMITED TO 10-20 FOR THE EVENING PERIOD.
SUNDAY THROUGH WEDNESDAY...DETERMINISTIC AND ENSEMBLE OUTPUT
CONTINUE TO SHOW A LOT OF SPREAD THROUGH THE ENTIRE PERIOD.
HOWEVER...IN GENERAL THEY ARE SHOWING A FAST FLOW WITH MULTIPLE
EMBEDDED SHORTWAVE TROUGHS MOVING THROUGH THIS FLOW. FOR THE AREA
THIS IS NOT A FAVORABLE FLOW FOR PULLING IN SIGNIFICANT MOISTURE FOR
THESE SYSTEMS TO WORK WITH. BASED ON THAT...MODEL TRENDS IN THE LAST
24 HOURS...AND COLLABORATION...REMOVED WHAT WAS LEFT OF THE CHANCE
OF PRECIPITATION THAT THE CRH INIT GAVE ME FOR MONDAY. SO IT IS NOW DRY
THROUGH THIS PERIOD. OTHER THAN THAT...SAW NO NEED TO MAKE ANY
CHANGES TO THE GUIDANCE GIVEN TO ME.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 417 AM MST THU DEC 13 2012
VFR CONDITIONS EXPECTED THROUGH 12Z FRIDAY WITH LIGHT WINDS
GRADUALLY BECOMING SOUTHEAST THROUGH THE DAY.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JRM
LONG TERM...JRM/BULLER
AVIATION...JRM
AREA FORECAST DISCUSSION
NWS GAYLORD MI
944 AM EST THU DEC 13 2012
.SYNOPSIS...
ISSUED AT 348 AM EST THU DEC 13 2012
A BROAD AREA OF HIGH PRESSURE OVER THE EAST COAST OF THE U. S. WILL
BRING QUIET...WARM WEATHER TO NORTHERN MICHIGAN THROUGH FRIDAY. LOW
PRESSURE WILL MOVE INTO THE WESTERN GREAT LAKES THIS WEEKEND AND
GENERATE RAIN OR SNOW OVER NORTHERN MICHIGAN SATURDAY AND SUNDAY.
COLDER AIR AND SNOW SHOWERS WILL SETTLE INTO THE GREAT LAKES TO
BEGIN THE UPCOMING WORK WEEK.
&&
.UPDATE...
ISSUED AT 943 AM EST THU DEC 13 2012
INCREASINGLY GUSTY SOUTHWEST FLOW ON BACKSIDE OF NEW ENGLAND
CENTERED HIGH PRESSURE ONCE AGAIN SPREADING ABOVE NORMAL WARMTH
ACROSS THE NORTH WOODS...WITH MID MORNING READINGS ALREADY PUSHING
40 DEGREES ALONG THE LAKE MICHIGAN SHORELINE. THESE TRENDS SHOULD
CONTINUE...WITH MAINTENANCE OF GUSTY SOUTHWEST WINDS RESULTING IN
AFTERNOON HIGHS MAKING A RUN INTO THE LOWER AND MIDDLE 40S. DESPITE
JUST OFF THE DECK LOW LEVEL WIND MAX...UPWARDS OF 40 KNOTS AT H925
PER LATEST HIGH RES RAP GUIDANCE...SHALLOW MIXING PREVENTING FULL
WIND POTENTIAL FROM REACHING THE SURFACE...SAFELY PUTTING WIND GUSTS
BELOW ADVISORY CRITERIA. STILL NO DOUBT A WINDY ONE...WITH GUSTS
THIS AFTERNOON LIKELY TOPPING 30 MPH. STILL A PLETHORA OF MID AND
UPPER LEVEL CLOUDS...ESPECIALLY ACROSS THE NORTH HALF OF THE
AREA...AHEAD OF LOW AMPLITUDE WAVE PIVOTING EAST ACROSS NORTHWEST
WISCONSIN/WESTERN LAKE SUPERIOR. SOME LIGHT RETURNS NOTED OVER
EASTERN UPPER MICHIGAN THIS MORNING FALLING FROM 11KFT CLOUD
DECK...ALTHOUGH DEARTH OF SUB H70 MOISTURE (SEE LOCAL 12Z SOUNDING)
PREVENTING ANYTHING FROM REACHING THE SURFACE. SOMEWHAT DEEPER
MOISTURE/FGEN DYNAMICS ASSOCIATED BACK CLOSER TO THE WAVE...WHERE
SOME LIGHT SNOW IS REACHING THE SURFACE. DEEPEST MOISTURE AND FGEN
DYNAMICS LOOK TO SLIDE ACROSS LAKE SUPERIOR THIS AFTERNOON...KEEPING
MOST...IF NOT ALL...RAIN/SNOW NORTH OF EASTERN UPPER. MAY YET SEE A
FEW SPRINKLES/FLURRIES...AND WILL SIMPLY RIDE WITH THIS GOING
INHERITED THEME.
UPDATE ISSUED AT 635 AM EST THU DEC 13 2012
FRESHENED UP SKY COVER GRIDS BASED ON SATELLITE TRENDS...OTHERWISE
NO MAJOR FORECAST CHANGES.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 348 AM EST THU DEC 13 2012
EARLY MORNING SURFACE ANALYSIS FINDS A WAVY FRONTAL BOUNDARY THAT
EXTENDS FROM NORTHWEST QUEBEC...BACK ACROSS NORTHERN ONTARIO TO A
FRONTAL WAVE OVER NORTHEAST MINNESOTA. ANOTHER QUASI-WARM FRONT RAN
NORTHWEST-SOUTHEAST FROM EASTERN LAKE SUPERIOR INTO THE LOWER GREAT
LAKES/NORTHERN NEW YORK. TIGHT GRADIENT BETWEEN THE MINNESOTA LOW
AND A 1031MB HIGH OVER WESTERN PENNSYLVANIA FUNNELING INCREASING
SOUTHERLY WINDS INTO MICHIGAN EARLY THIS MORNING. MAIN CENTERS OF
ACTION ALOFT ARE A DIGGING TROUGH INTO SOUTHERN CALIFORNIA...AND
ANOTHER SHORT WAVE TROUGH LIFTING OUT OVER THE SOUTHEASTERN U.S..
WATER VAPOR IMAGERY ALSO REVEALS A SMALL VORTICITY CENTER OVER THE
DAKOTAS ASSOCIATED WITH A 60KT MID LEVEL JET STREAK. WARM ADVECTION
HAS DRAGGED MID/HIGH CLOUDS ACROSS THE FORECAST AREA EARLY THIS
MORNING...WITH RADAR RETURNS ACROSS NORTHERN MICHIGAN EXTENDING BACK
ACROSS THE UPPER PENINSULA. BUT DRY AIR BELOW 725MB PER 00Z APX/GRB
SOUNDINGS PRECLUDING MUCH IN THE WAY OF SURFACE PRECIPITATION
REPORTS (SOME LIGHT PRECIP AT ERY/YAM).
SURFACE WAVE OVER MINNESOTA EXPECTED TO HEAD EAST-NORTHEAST TODAY
TOWARD WEAK PRESSURE FALL CENTER NORTH OF LAKE SUPERIOR. ASSOCIATED
FRONTAL BOUNDARY WILL GET STRETCHED IN A NORTHEAST-SOUTHWEST
FASHION ACROSS THE UPPER MIDWEST AND THE UPPER PENINSULA...WITH THE
BOUNDARY EXPECTED TO DROOP INTO THE STRAITS REGION OVERNIGHT. SHEAR
VORTICITY CENTER OVER THE DAKOTAS WILL EVENTUALLY SLIDE ACROSS
NORTHERN MICHIGAN THIS AFTERNOON. BUT OVERALL FORECAST CONCERNS ARE
MINIMAL...MAINLY DEALING WITH TEMPERATURES/WINDS TODAY...AND
TEMPERATURES TONIGHT WITH THE SAGGING COLD FRONT.
NORTH-SOUTH "GRADIENT" IN CLOUD COVER EXPECTED TODAY WITH SATELLITE
TRENDS SUPPORTING THE IDEA OF THICKER MID CLOUDS REMAINING ACROSS
UPPER MICHIGAN TODAY...AIDED BY ARRIVAL OF ABOVE MENTIONED SHORT
WAVE/SHEAR VORTICITY CENTER...WHILE CLOUD COVER THINS OUT FROM NORTH
TO SOUTH ACROSS THE LOWER PENINSULA. 00Z 850MB ANALYSIS SHOWS AN
AREA OF HIGHER DEW POINTS ACROSS EASTERN SOUTH DAKOTA/NORTHERN
MINNESOTA THAT GETS PULLED EAST ACROSS THE UPPER PENINSULA...AND
WITH THE ARRIVAL OF ADDITIONAL FORCING LATER TODAY QUESTION IS THERE
WHERE DRY LAYER CAN BE ERODED SUFFICIENTLY TO ALLOW FOR SOME LIGHT
PRECIPITATION. PROBABLY NOT WORTH A MEASURABLE POP MENTION OUTSIDE
OF MAYBE WHITEFISH BAY AND POINTS NORTH. WINDS ARE GOING TO BE
ANOTHER CONCERN...WITH FORECAST SOUNDINGS SHOWING TYPICAL INABILITY
TO DEPICT MIXING OVER SNOW COVER. A 30-40KT SOUTHWESTERLY LOW LEVEL
JET RIGHT OFF THE DECK (3K FEET AGL WIND OFF KAPX VWP ALREADY
35-40KT) WON`T REQUIRE MUCH MIXING TO PULL STRONGER GUSTS DOWN TO
THE SURFACE (EVIDENT IN 35KT GUST IN ERY 0735Z OB...THOUGH POSSIBLY
AIDED BY EVAPORATIVE COOLING WITH SOME LIGHT RAIN AT THE TIME).
ANTICIPATE WIND GUSTS OF 30-40 MPH ACROSS NORTHERN LOWER THIS
AFTERNOON...DIMINISHING TOWARD EVENING. TEMPERATURES ALREADY ON THE
WAY UP THIS MORNING...WITH WIDESPREAD MID/UPPER 30S WITH A FEW 40
DEGREE READINGS. A MILD START COMBINED WITH GOOD MECHANICAL MIXING
SHOULD PUSH TEMPERATURES WELL INTO THE 40S THIS AFTERNOON...A GOOD
10-15 DEGREES ABOVE MID DECEMBER NORMALS.
STRETCHED OUT COLD FRONT GRADUALLY SINKS INTO UPPER MICHIGAN AND THE
STRAITS REGION OVERNIGHT. GOOD DEAL OF POST-FRONTAL LOW CLOUD
ALREADY IN PLACE...AND COMBINED WITH LOW LEVEL COLD ADVECTION
LEADING TO SHALLOW INSTABILITY DEVELOPING OVER LAKE SUPERIOR AND FAR
NORTHERN LAKE MICHIGAN...EXPECT SKIES TO REMAIN ON THE CLOUDY SIDE
ACROSS UPPER MICHIGAN TONIGHT...WITH CLOUDS SPILLING INTO NORTHERN
LOWER MICHIGAN OVERNIGHT WITH THE FRONT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 348 AM EST THU DEC 13 2012
FRIDAY...500 MB HEIGHTS RISE AND THE 850 MB TEMPERATURES REMAIN
AROUND 0C IN N LOWER. 850 MB RH IS AROUND 50% AND WITH THE
MID-LEVELS (700-500 MB) STILL PRETTY DRY. THIS WILL LEAVE THE REGION
DRY.
FRIDAY NIGHT...THE MOISTURE FROM THE NEXT SYSTEM MOVES INTO THE
REGION AND CLOUDS WILL INCREASE. LOOKS LIKE WITH THE 500 MB RIDGE
OVER US THAT THE RAIN/SNOW WILL BE HELD OFF UNTIL THE DAY ON
SATURDAY.
SATURDAY...AS THE LOW MOVES OUT OF THE CENTRAL PLAINS, THE MOISTURE
MOVES ACROSS THE REGION. BOTH MODELS START OUT WITH 850 MB
TEMPERATURES OVER NW LOWER WARM ENOUGH TO PRODUCE SNOW/RAIN/FREEZING
RAIN IN THE MORNING. HOWEVER, BY THE AFTERNOON, IT LOOKS LIKE A
SNOW/RAIN MIX ON THE ECMWF AS THE BELOW 0C AIR AT 850 MB HAS DROPPED
SOUTH INTO S LOWER. THIS SEEMS TO BE FROM EVAP COOLING. THE ECMWF
SOUNDINGS FOR 12Z SHOWED A LAYER OF DRY AIR OVER THE FORECAST AREA,
THAT WOULD ALLOW THE COOLING AT 850 MB. THE GFS SHOWS THE MOISTURE
MOVING IN RAPIDLY AND ALLOWING THE WARMER AIR CONTINUE SO THAT IT IS
ONLY RAIN IN THE SOUTHERN COUNTIES OF THE FORECAST AREA. SO LOOKS
LIKE THERE IS A CHANCE FOR RAIN OR SNOW OR SOME KIND OF MIX.
OVERNIGHT, THE MODELS CONTINUE THE TOSS UP, HOWEVER, IT DOES LOOK
LIKE E UPPER SHOULD BE COLD ENOUGH FOR A SNOW ONLY FORECAST FROM THE
OUTSET. HOWEVER, THE AMOUNTS SHOULD BE MINOR TO LIGHT AS E UPPER
REMAINS A GOOD DISTANCE FROM THE MAIN FORCING. OVERNIGHT, THE WARMER
AIR MOVES INTO AN AREA SOUTH AND EAST OF A LINE FROM APN TO MBL. SO
WILL HAVE RAIN LIKELY, AND A RAIN/SNOW MIX NORTH AND WEST TO THE
STRAITS, NORTH OF WHICH WILL BE ALL SNOW. AFTER THE ECMWF MADE ITS
COURSE CORRECTION A COUPLE OF DAYS AGO, IT LOOKED LIKE IT WAS
HOLDING PRETTY CONSISTENT ON THE TRACK OF THE LOW ALONG I-96.
HOWEVER, WITH THE 00Z, THE ECMWF HAS INTRODUCED WARM AIR AT 850 MB
FARTHER NORTH IN N LOWER, SO THAT NOW SATURDAY NIGHT LOOKS LIKE RAIN
UP TO M-72 AND RAIN OR SNOW NORTH.
EXTENDED (SUNDAY THROUGH WEDNESDAY)...SUNDAY, AND THIS WARM TRACK
FOR THE ECMWF CONTINUES ON INTO THE DAY AND NOT UNTIL THE SFC LOW
MOVES EAST OF THE REGION WILL THE COLD AIR MOVE BACK INTO THE REGION
AND SNOW BECOMES DOMINATE AGAIN AND THAT DOESN`T LOOK LIKELY UNTIL
SUNDAY NIGHT. CONSIDERING THE LIKELIHOOD OF THE EAST COASTAL SYSTEM
BEGINNING TO DEVELOP, NOT SURE WHICH MODEL HAS THE UPPER HAND.
MONDAY, NE TO N FLOW WITH THE 850 MB TEMPERATURES IN N LAKE MICHIGAN
AROUND -6C PUTS US AROUND 13-14C DELTA T. SO MARGINAL DELTA T AND NE
FLOW DOESN`T DO MUCH LES IN NW LOWER. IN NE LOWER, THE 850 MB
TEMPERATURES ARE WARMER, SO UNLIKELY THERE WILL BE MUCH IN THE WAY
OF ENHANCEMENT. TEMPERATURE CONTINUE TO COOL AND THE WINDS GO NNW
OVERNIGHT, SO HAVE INCREASED THE POPS TO ALLOW SOME CHANCE POPS IN
THE NNW FLOW AREAS. TUESDAY, THE REAL COLD AIR WITH THIS SYSTEM
STAYS BOTTLED UP UNTIL TUESDAY MORNING WITH THE SYSTEM MOVING UP THE
EAST COAST AND THE WINDS OUT OF THE NW OVER THE FORECAST AREA. SO
BUMPED UP THE POPS FOR LOW CHANCE SNOW FROM LES. WEDNESDAY, THE 500
MB RIDGE MOVE THROUGH THE REGION AND THE WINDS REVERSE OUT OF THE SE
AGAIN. THIS BRINGS WARM AIR NORTH AHEAD OF THE NEXT FRONT. THE GFS
HAS SOME SNOW, AND THE ECMWF IS DRY, SO LOW CHANCE POPS FOR SNOW FOR
NOW.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 635 AM EST THU DEC 13 2012
VFR PREVAILING CONDITIONS EXPECTED THROUGH TONIGHT. GUSTY WINDS
TODAY FROM THE SOUTHWEST...PERHAPS A BRIEF PERIOD OF LOW LEVEL
WIND SHEAR THIS EVENING BEFORE WINDS SLACK OFF.
&&
.MARINE...
ISSUED AT 348 AM EST THU DEC 13 2012
GUSTY SOUTH/SOUTHWEST WINDS THIS MORNING...WITH SOME MARGINAL GALE
FORCE GUSTS ON NORTHERN LAKE MICHIGAN. WILL KEEP GALE WARNINGS FOR
THIS MORNING ON NORTHERN LAKE MICHIGAN...WHICH WILL NEED TO
TRANSITION OF SMALL CRAFT ADVISORIES FOR AT LEAST THIS AFTERNOON IF
NOT INTO TONIGHT DUE TO CHOPPY SEAS. ALSO ANTICIPATE SMALL CRAFT
ADVISORIES FOR REMAINING NEARSHORE ZONES THROUGH TODAY WITH THE
POSSIBLE EXCEPTION OF WHITEFISH BAY. WIND SPEEDS WILL DROP THIS
EVENING AND WINDS WILL VEER TO A MORE WEST OR NORTHWEST DIRECTION AS
A COLD FRONT SAGS ACROSS THE UPPER PENINSULA.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
LHZ345>349.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR LMZ323.
GALE WARNING UNTIL 11 AM EST THIS MORNING FOR LMZ341-342-344>346.
LS...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR LSZ322.
&&
$$
UPDATE...MB
SYNOPSIS...JSL
SHORT TERM...JPB
LONG TERM...JSL
MARINE...JPB
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1050 AM MST THU DEC 13 2012
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 158 AM MST THU DEC 13 2012
04Z WATER VAPOR IMAGERY AND RAP ANALYSIS INDICATED LOW AMPLITUDE H5
RIDGE IN PLACE ACROSS THE REGION WITH STRONG TROUGH ALONG AND JUST
OF THE WEST COAST. THIS SYSTEM WILL PLAY A LARGE ROLE ON EXPECTED
WEATHER THROUGH THE START OF THE WEEKEND...AND IS STILL NOT TOTALLY
BEING SAMPLED BY UPPER AIR NETWORK. 00Z SOUNDINGS INDICATED A DRY
AND MUCH WARMER AIRMASS THAN 24 HOURS AGO...WITH STRONGEST WARMING
BETWEEN H8 AND H6. AT THE SFC...TROUGH AXIS WAS IN PLACE ALONG
ROUGHLY A KLBF TO KTRB LINE.
MAIN FORECAST CONCERNS WILL BE SKY COVER THIS MORNING AND TONIGHT
DUE TO GEMINID METEOR SHOWER AND PRECIPITATION POTENTIAL FRIDAY.
TODAY-TONIGHT...SHORT WAVE RIDGING WILL CONTINUE ACROSS THE AREA
THROUGH THE EVENING AND ALTHOUGH WEAK AMPLITUDE WILL NOT CREATE ANY
STRONG SUBSIDENCE DRY AND STABLE CONDITIONS EXPECTED SO ANY WEAK
ASCENT WILL NOT HAVE MUCH OF AN IMPACT ON SENSIBLE WEATHER. ALREADY
SEEING A LOT OF CIRRUS MOVING OVER THE AREA...WITH 80-90KT H3 WINDS
HELPING INDUCE CIRRUS DOWNSTREAM OF THE MOUNTAINS. GIVEN EXPECTED
FLOW ALOFT...EXPECT CLOUD COVER TO PERSIST THROUGH THE MORNING HOURS
WHICH WILL LIKELY INHIBIT THE VIEWING OF METEOR SHOWER IN SOME
LOCATIONS. SKIES WILL CLEAR DURING THE AFTERNOON AS FLOW ALOFT
BECOMES LESS PERPENDICULAR TO MOUNTAINS AND RRQ OF H3 JET STREAK
SHIFT TO THE NORTH AND EAST ACROSS SOUTH DAKOTA. WHILE CIRRUS WILL
LINGER ACROSS NORTHERN CWA TONIGHT...SHOULD BE A FEW PERIODS WHERE
CLOUDS CLEAR UP ALTHOUGH CLOUD COVER WILL BEGIN TO INCREASE RAPIDLY
FROM THE SOUTHWEST AFTER 2 AM MST (3 AM CST) AS NEXT SYSTEM
APPROACHES.
FRIDAY...MUCH MORE ACTIVE WEATHER IS EXPECTED ACROSS THE CWA ON
FRIDAY AS STRONG TROUGH BEGINS TO MOVE OVER THE AREA. MODELS HAVE
COME INTO MUCH BETTER AGREEMENT WITH TIMING OF FAIRLY PROGRESSIVE
TROUGH ACROSS THE PLAINS...ALTHOUGH LOOKING AT THE INDIVIDUAL
DYNAMIC TROP ANALYSIS FROM THE GFS AND NAM...AM A LITTLE CONCERNED
WITH GFS DEPICTING A MUCH LESS CONSOLIDATED PV ANOMALY WHICH OFTEN
TENDS TO HINDER WIDESPREAD PERSISTENT PRECIPITATION RATHER THAN HELP.
WHILE THE POSSIBILITY OF TROUGH COMING OUT IN PIECES LOWERS
CONFIDENCE SOMEWHAT...ENOUGH AGREEMENT BETWEEN OPERATIONAL MODELS TO
SUPPORT PROBABLY ONE OF THE BETTER CHANCES FOR PRECIP OVER THE PAST
MONTH AND BASED ON ALL FACTORS THINK 30-60 PROBABILITIES WARRANTED.
BEST CHANCES WILL BE ACROSS EASTERN CWA WHERE ISENTROPIC ANALYSIS
INDICATES STRONGEST MOISTURE TRANSPORT IN THIS AREA WITH A SECOND
MAXIMUM IN FORCING LOCATED TO NORTH OF SFC WARM FRONT IN NORTHWEST
CWA. DEPENDING ON HOW QUICKLY CLEARING OCCURS ONCE DRY SLOT
CIRCULATION BEGINS TO ENTER CWA COULD POSSIBLY SEE A SFC BASED
THUNDERSTORM ALONG DRY LINE IN SOUTHEASTERN ZONES AROUND SUNSET.
WHILE THERE IS SOME DATA SUGGESTING A CHANGE OVER TO SNOW IS
POSSIBLE IN THE WEST DURING THE AFTERNOON...AM GOING TO LEAN TOWARDS
A CONSENSUS OF AVAILABLE DATA AND HOLD OFF ON ANY COMPLETE CHANGE
OVER UNTIL AFTER 00Z.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 158 AM MST THU DEC 13 2012
FRIDAY NIGHT-SATURDAY NIGHT...EXPECT PRECIP CHANCES TO BE MAXIMIZED
RIGHT AROUND SUNSET ON FRIDAY NIGHT BEFORE PRECIP CHANCES BEGIN TO
END FROM SOUTHWEST TO NORTHEAST AS DOWNWARD MOTION INTENSIFIES
BEHIND DEPARTING TROUGH. AM A LITTLE CONCERNED ABOUT POTENTIAL FOR
ACCUMULATING SNOW ACROSS NORTHWEST CWA WITH POTENTIAL INSTABILITY
PRESENT AND PERSISTENT...NEARLY STATIONARY AREA OF LOW LEVEL
FRONTOGENESIS. HOWEVER...THIS AREA WOULD BE ONE OF THE FIRST AREAS
FOR FORCING TO DIMINISH AS UPPER LEVEL FLOW BECOMES SUBSIDENT AND
AFTER LOOKING AT PAST FEW ROUNDS OF ANALOG GUIDANCE...DO NOT THINK
PROBABILITY FOR MEANINGFUL SNOWFALL ACCUMULATIONS IS ALL THAT HIGH.
WINDS WILL LIKELY PICK UP INTO THE 20-30 MPH RANGE AS SYSTEM
DEPARTS...BUT EXPECT ANY POTENTIAL SNOW TO BE OVER WITH BEFORE WINDS
DEVELOP.
ON SATURDAY...STRONG DOWNWARD MOTION WILL BRING AN END TO THE
PRECIPITATION THREAT AND BRING SOME CLEARING TO THE AREA IN THE
MORNING...WITH CLOUDS BEGINNING TO INCREASE LATE IN THE AFTERNOON AS
A WEAK SHORT WAVE TROUGH APPROACHES. WHILE MODELS/ENSEMBLES
GENERALLY SUPPORT A PRECIPITATION THREAT...HAVE CONCERNS THAT A LOW
AMPLITUDE/TRANSIENT DISTURBANCE WILL PROVIDE ENOUGH FORCED ASCENT TO
SATURATE DRY LOWER LEVELS LEFT IN WAKE OF PREVIOUS SYSTEM AND WILL
KEEP POPS LIMITED TO 10-20 FOR THE EVENING PERIOD.
SUNDAY THROUGH WEDNESDAY...DETERMINISTIC AND ENSEMBLE OUTPUT
CONTINUE TO SHOW A LOT OF SPREAD THROUGH THE ENTIRE PERIOD.
HOWEVER...IN GENERAL THEY ARE SHOWING A FAST FLOW WITH MULTIPLE
EMBEDDED SHORTWAVE TROUGHS MOVING THROUGH THIS FLOW. FOR THE AREA
THIS IS NOT A FAVORABLE FLOW FOR PULLING IN SIGNIFICANT MOISTURE FOR
THESE SYSTEMS TO WORK WITH. BASED ON THAT...MODEL TRENDS IN THE LAST
24 HOURS...AND COLLABORATION...REMOVED WHAT WAS LEFT OF THE CHANCE
OF PRECIPITATION THAT THE CRH INIT GAVE ME FOR MONDAY. SO IT IS NOW DRY
THROUGH THIS PERIOD. OTHER THAN THAT...SAW NO NEED TO MAKE ANY
CHANGES TO THE GUIDANCE GIVEN TO ME.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1043 AM MST THU DEC 13 2012
VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE PREVAILING TAF
PERIOD. WINDS WILL REMAIN LIGHT AND VARIABLE AT BOTH TERMINALS
THROUGH TOMORROW MORNING BEFORE BECOMING PREDOMINATELY SOUTHERLY
AHEAD OF AN INCOMING STORM SYSTEM. CLOUD COVER WILL INCREASE AND
CIGS WILL BEGIN TO LOWER LATE IN THE PERIOD AS THIS SYSTEM APPROACHES
THE REGION.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JRM
LONG TERM...JRM/BULLER
AVIATION...PMM
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1251 PM EST THU DEC 13 2012
.SYNOPSIS...
ISSUED AT 348 AM EST THU DEC 13 2012
A BROAD AREA OF HIGH PRESSURE OVER THE EAST COAST OF THE U. S. WILL
BRING QUIET...WARM WEATHER TO NORTHERN MICHIGAN THROUGH FRIDAY. LOW
PRESSURE WILL MOVE INTO THE WESTERN GREAT LAKES THIS WEEKEND AND
GENERATE RAIN OR SNOW OVER NORTHERN MICHIGAN SATURDAY AND SUNDAY.
COLDER AIR AND SNOW SHOWERS WILL SETTLE INTO THE GREAT LAKES TO
BEGIN THE UPCOMING WORK WEEK.
&&
.UPDATE...
ISSUED AT 1246 PM EST THU DEC 13 2012
NO NOTEWORTHY CHANGES NEEDED AS ABOVE NORMAL WARMTH VIA GUSTY
SOUTHWEST WINDS CONTINUE.
UPDATE ISSUED AT 943 AM EST THU DEC 13 2012
INCREASINGLY GUSTY SOUTHWEST FLOW ON BACKSIDE OF NEW ENGLAND
CENTERED HIGH PRESSURE ONCE AGAIN SPREADING ABOVE NORMAL WARMTH
ACROSS THE NORTH WOODS...WITH MID MORNING READINGS ALREADY PUSHING
40 DEGREES ALONG THE LAKE MICHIGAN SHORELINE. THESE TRENDS SHOULD
CONTINUE...WITH MAINTENANCE OF GUSTY SOUTHWEST WINDS RESULTING IN
AFTERNOON HIGHS MAKING A RUN INTO THE LOWER AND MIDDLE 40S. DESPITE
JUST OFF THE DECK LOW LEVEL WIND MAX...UPWARDS OF 40 KNOTS AT H925
PER LATEST HIGH RES RAP GUIDANCE...SHALLOW MIXING PREVENTING FULL
WIND POTENTIAL FROM REACHING THE SURFACE...SAFELY PUTTING WIND GUSTS
BELOW ADVISORY CRITERIA. STILL NO DOUBT A WINDY ONE...WITH GUSTS
THIS AFTERNOON LIKELY TOPPING 30 MPH. STILL A PLETHORA OF MID AND
UPPER LEVEL CLOUDS...ESPECIALLY ACROSS THE NORTH HALF OF THE
AREA...AHEAD OF LOW AMPLITUDE WAVE PIVOTING EAST ACROSS NORTHWEST
WISCONSIN/WESTERN LAKE SUPERIOR. SOME LIGHT RETURNS NOTED OVER
EASTERN UPPER MICHIGAN THIS MORNING FALLING FROM 11KFT CLOUD
DECK...ALTHOUGH DEARTH OF SUB H70 MOISTURE (SEE LOCAL 12Z SOUNDING)
PREVENTING ANYTHING FROM REACHING THE SURFACE. SOMEWHAT DEEPER
MOISTURE/FGEN DYNAMICS ASSOCIATED BACK CLOSER TO THE WAVE...WHERE
SOME LIGHT SNOW IS REACHING THE SURFACE. DEEPEST MOISTURE AND FGEN
DYNAMICS LOOK TO SLIDE ACROSS LAKE SUPERIOR THIS AFTERNOON...KEEPING
MOST...IF NOT ALL...RAIN/SNOW NORTH OF EASTERN UPPER. MAY YET SEE A
FEW SPRINKLES/FLURRIES...AND WILL SIMPLY RIDE WITH THIS GOING
INHERITED THEME.
UPDATE ISSUED AT 635 AM EST THU DEC 13 2012
FRESHENED UP SKY COVER GRIDS BASED ON SATELLITE TRENDS...OTHERWISE
NO MAJOR FORECAST CHANGES.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 348 AM EST THU DEC 13 2012
EARLY MORNING SURFACE ANALYSIS FINDS A WAVY FRONTAL BOUNDARY THAT
EXTENDS FROM NORTHWEST QUEBEC...BACK ACROSS NORTHERN ONTARIO TO A
FRONTAL WAVE OVER NORTHEAST MINNESOTA. ANOTHER QUASI-WARM FRONT RAN
NORTHWEST-SOUTHEAST FROM EASTERN LAKE SUPERIOR INTO THE LOWER GREAT
LAKES/NORTHERN NEW YORK. TIGHT GRADIENT BETWEEN THE MINNESOTA LOW
AND A 1031MB HIGH OVER WESTERN PENNSYLVANIA FUNNELING INCREASING
SOUTHERLY WINDS INTO MICHIGAN EARLY THIS MORNING. MAIN CENTERS OF
ACTION ALOFT ARE A DIGGING TROUGH INTO SOUTHERN CALIFORNIA...AND
ANOTHER SHORT WAVE TROUGH LIFTING OUT OVER THE SOUTHEASTERN U.S..
WATER VAPOR IMAGERY ALSO REVEALS A SMALL VORTICITY CENTER OVER THE
DAKOTAS ASSOCIATED WITH A 60KT MID LEVEL JET STREAK. WARM ADVECTION
HAS DRAGGED MID/HIGH CLOUDS ACROSS THE FORECAST AREA EARLY THIS
MORNING...WITH RADAR RETURNS ACROSS NORTHERN MICHIGAN EXTENDING BACK
ACROSS THE UPPER PENINSULA. BUT DRY AIR BELOW 725MB PER 00Z APX/GRB
SOUNDINGS PRECLUDING MUCH IN THE WAY OF SURFACE PRECIPITATION
REPORTS (SOME LIGHT PRECIP AT ERY/YAM).
SURFACE WAVE OVER MINNESOTA EXPECTED TO HEAD EAST-NORTHEAST TODAY
TOWARD WEAK PRESSURE FALL CENTER NORTH OF LAKE SUPERIOR. ASSOCIATED
FRONTAL BOUNDARY WILL GET STRETCHED IN A NORTHEAST-SOUTHWEST
FASHION ACROSS THE UPPER MIDWEST AND THE UPPER PENINSULA...WITH THE
BOUNDARY EXPECTED TO DROOP INTO THE STRAITS REGION OVERNIGHT. SHEAR
VORTICITY CENTER OVER THE DAKOTAS WILL EVENTUALLY SLIDE ACROSS
NORTHERN MICHIGAN THIS AFTERNOON. BUT OVERALL FORECAST CONCERNS ARE
MINIMAL...MAINLY DEALING WITH TEMPERATURES/WINDS TODAY...AND
TEMPERATURES TONIGHT WITH THE SAGGING COLD FRONT.
NORTH-SOUTH "GRADIENT" IN CLOUD COVER EXPECTED TODAY WITH SATELLITE
TRENDS SUPPORTING THE IDEA OF THICKER MID CLOUDS REMAINING ACROSS
UPPER MICHIGAN TODAY...AIDED BY ARRIVAL OF ABOVE MENTIONED SHORT
WAVE/SHEAR VORTICITY CENTER...WHILE CLOUD COVER THINS OUT FROM NORTH
TO SOUTH ACROSS THE LOWER PENINSULA. 00Z 850MB ANALYSIS SHOWS AN
AREA OF HIGHER DEW POINTS ACROSS EASTERN SOUTH DAKOTA/NORTHERN
MINNESOTA THAT GETS PULLED EAST ACROSS THE UPPER PENINSULA...AND
WITH THE ARRIVAL OF ADDITIONAL FORCING LATER TODAY QUESTION IS THERE
WHERE DRY LAYER CAN BE ERODED SUFFICIENTLY TO ALLOW FOR SOME LIGHT
PRECIPITATION. PROBABLY NOT WORTH A MEASURABLE POP MENTION OUTSIDE
OF MAYBE WHITEFISH BAY AND POINTS NORTH. WINDS ARE GOING TO BE
ANOTHER CONCERN...WITH FORECAST SOUNDINGS SHOWING TYPICAL INABILITY
TO DEPICT MIXING OVER SNOW COVER. A 30-40KT SOUTHWESTERLY LOW LEVEL
JET RIGHT OFF THE DECK (3K FEET AGL WIND OFF KAPX VWP ALREADY
35-40KT) WON`T REQUIRE MUCH MIXING TO PULL STRONGER GUSTS DOWN TO
THE SURFACE (EVIDENT IN 35KT GUST IN ERY 0735Z OB...THOUGH POSSIBLY
AIDED BY EVAPORATIVE COOLING WITH SOME LIGHT RAIN AT THE TIME).
ANTICIPATE WIND GUSTS OF 30-40 MPH ACROSS NORTHERN LOWER THIS
AFTERNOON...DIMINISHING TOWARD EVENING. TEMPERATURES ALREADY ON THE
WAY UP THIS MORNING...WITH WIDESPREAD MID/UPPER 30S WITH A FEW 40
DEGREE READINGS. A MILD START COMBINED WITH GOOD MECHANICAL MIXING
SHOULD PUSH TEMPERATURES WELL INTO THE 40S THIS AFTERNOON...A GOOD
10-15 DEGREES ABOVE MID DECEMBER NORMALS.
STRETCHED OUT COLD FRONT GRADUALLY SINKS INTO UPPER MICHIGAN AND THE
STRAITS REGION OVERNIGHT. GOOD DEAL OF POST-FRONTAL LOW CLOUD
ALREADY IN PLACE...AND COMBINED WITH LOW LEVEL COLD ADVECTION
LEADING TO SHALLOW INSTABILITY DEVELOPING OVER LAKE SUPERIOR AND FAR
NORTHERN LAKE MICHIGAN...EXPECT SKIES TO REMAIN ON THE CLOUDY SIDE
ACROSS UPPER MICHIGAN TONIGHT...WITH CLOUDS SPILLING INTO NORTHERN
LOWER MICHIGAN OVERNIGHT WITH THE FRONT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 348 AM EST THU DEC 13 2012
FRIDAY...500 MB HEIGHTS RISE AND THE 850 MB TEMPERATURES REMAIN
AROUND 0C IN N LOWER. 850 MB RH IS AROUND 50% AND WITH THE
MID-LEVELS (700-500 MB) STILL PRETTY DRY. THIS WILL LEAVE THE REGION
DRY.
FRIDAY NIGHT...THE MOISTURE FROM THE NEXT SYSTEM MOVES INTO THE
REGION AND CLOUDS WILL INCREASE. LOOKS LIKE WITH THE 500 MB RIDGE
OVER US THAT THE RAIN/SNOW WILL BE HELD OFF UNTIL THE DAY ON
SATURDAY.
SATURDAY...AS THE LOW MOVES OUT OF THE CENTRAL PLAINS, THE MOISTURE
MOVES ACROSS THE REGION. BOTH MODELS START OUT WITH 850 MB
TEMPERATURES OVER NW LOWER WARM ENOUGH TO PRODUCE SNOW/RAIN/FREEZING
RAIN IN THE MORNING. HOWEVER, BY THE AFTERNOON, IT LOOKS LIKE A
SNOW/RAIN MIX ON THE ECMWF AS THE BELOW 0C AIR AT 850 MB HAS DROPPED
SOUTH INTO S LOWER. THIS SEEMS TO BE FROM EVAP COOLING. THE ECMWF
SOUNDINGS FOR 12Z SHOWED A LAYER OF DRY AIR OVER THE FORECAST AREA,
THAT WOULD ALLOW THE COOLING AT 850 MB. THE GFS SHOWS THE MOISTURE
MOVING IN RAPIDLY AND ALLOWING THE WARMER AIR CONTINUE SO THAT IT IS
ONLY RAIN IN THE SOUTHERN COUNTIES OF THE FORECAST AREA. SO LOOKS
LIKE THERE IS A CHANCE FOR RAIN OR SNOW OR SOME KIND OF MIX.
OVERNIGHT, THE MODELS CONTINUE THE TOSS UP, HOWEVER, IT DOES LOOK
LIKE E UPPER SHOULD BE COLD ENOUGH FOR A SNOW ONLY FORECAST FROM THE
OUTSET. HOWEVER, THE AMOUNTS SHOULD BE MINOR TO LIGHT AS E UPPER
REMAINS A GOOD DISTANCE FROM THE MAIN FORCING. OVERNIGHT, THE WARMER
AIR MOVES INTO AN AREA SOUTH AND EAST OF A LINE FROM APN TO MBL. SO
WILL HAVE RAIN LIKELY, AND A RAIN/SNOW MIX NORTH AND WEST TO THE
STRAITS, NORTH OF WHICH WILL BE ALL SNOW. AFTER THE ECMWF MADE ITS
COURSE CORRECTION A COUPLE OF DAYS AGO, IT LOOKED LIKE IT WAS
HOLDING PRETTY CONSISTENT ON THE TRACK OF THE LOW ALONG I-96.
HOWEVER, WITH THE 00Z, THE ECMWF HAS INTRODUCED WARM AIR AT 850 MB
FARTHER NORTH IN N LOWER, SO THAT NOW SATURDAY NIGHT LOOKS LIKE RAIN
UP TO M-72 AND RAIN OR SNOW NORTH.
EXTENDED (SUNDAY THROUGH WEDNESDAY)...SUNDAY, AND THIS WARM TRACK
FOR THE ECMWF CONTINUES ON INTO THE DAY AND NOT UNTIL THE SFC LOW
MOVES EAST OF THE REGION WILL THE COLD AIR MOVE BACK INTO THE REGION
AND SNOW BECOMES DOMINATE AGAIN AND THAT DOESN`T LOOK LIKELY UNTIL
SUNDAY NIGHT. CONSIDERING THE LIKELIHOOD OF THE EAST COASTAL SYSTEM
BEGINNING TO DEVELOP, NOT SURE WHICH MODEL HAS THE UPPER HAND.
MONDAY, NE TO N FLOW WITH THE 850 MB TEMPERATURES IN N LAKE MICHIGAN
AROUND -6C PUTS US AROUND 13-14C DELTA T. SO MARGINAL DELTA T AND NE
FLOW DOESN`T DO MUCH LES IN NW LOWER. IN NE LOWER, THE 850 MB
TEMPERATURES ARE WARMER, SO UNLIKELY THERE WILL BE MUCH IN THE WAY
OF ENHANCEMENT. TEMPERATURE CONTINUE TO COOL AND THE WINDS GO NNW
OVERNIGHT, SO HAVE INCREASED THE POPS TO ALLOW SOME CHANCE POPS IN
THE NNW FLOW AREAS. TUESDAY, THE REAL COLD AIR WITH THIS SYSTEM
STAYS BOTTLED UP UNTIL TUESDAY MORNING WITH THE SYSTEM MOVING UP THE
EAST COAST AND THE WINDS OUT OF THE NW OVER THE FORECAST AREA. SO
BUMPED UP THE POPS FOR LOW CHANCE SNOW FROM LES. WEDNESDAY, THE 500
MB RIDGE MOVE THROUGH THE REGION AND THE WINDS REVERSE OUT OF THE SE
AGAIN. THIS BRINGS WARM AIR NORTH AHEAD OF THE NEXT FRONT. THE GFS
HAS SOME SNOW, AND THE ECMWF IS DRY, SO LOW CHANCE POPS FOR SNOW FOR
NOW.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1246 PM EST THU DEC 13 2012
GUSTY SOUTHWEST WINDS EXPECTED FOR THE REMAINDER OF THIS AFTERNOON
WELL AHEAD OF A DECAYING COLD FRONT DROPPING IN FROM THE NORTHWEST
LAKES. LOW LEVEL MOISTURE WILL DEEPEN TONIGHT...AND COMBINED WITH
PASSING FRONTAL FEATURE AND QUICKLY SUBSIDING WINDS...WILL LIKELY
KICK OFF AN EXPANDING AREA OF MVFR STRATUS...WITH EVEN SOME FOG
POTENTIAL (ALTHOUGH FOG POTENTIAL IS GREATEST OVER THE INTERIOR
HIGHLANDS). WILL NEED TO MONITOR CLOSELY...AS POTENTIAL FOR IFR
OVERCAST EXISTS AND FOG MAY BECOME MORE EXTENSIVE THAN CURRENTLY
FORECAST. SLOW IMPROVEMENT FRIDAY IN LIGHT WIND REGIME.
&&
.MARINE...
ISSUED AT 348 AM EST THU DEC 13 2012
GUSTY SOUTH/SOUTHWEST WINDS THIS MORNING...WITH SOME MARGINAL GALE
FORCE GUSTS ON NORTHERN LAKE MICHIGAN. WILL KEEP GALE WARNINGS FOR
THIS MORNING ON NORTHERN LAKE MICHIGAN...WHICH WILL NEED TO
TRANSITION OF SMALL CRAFT ADVISORIES FOR AT LEAST THIS AFTERNOON IF
NOT INTO TONIGHT DUE TO CHOPPY SEAS. ALSO ANTICIPATE SMALL CRAFT
ADVISORIES FOR REMAINING NEARSHORE ZONES THROUGH TODAY WITH THE
POSSIBLE EXCEPTION OF WHITEFISH BAY. WIND SPEEDS WILL DROP THIS
EVENING AND WINDS WILL VEER TO A MORE WEST OR NORTHWEST DIRECTION AS
A COLD FRONT SAGS ACROSS THE UPPER PENINSULA.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
LHZ345>349.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR LMZ323-
341-342-344>346.
LS...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR LSZ322.
&&
$$
UPDATE...MB
SYNOPSIS...JSL
SHORT TERM...JPB
LONG TERM...JSL
AVIATION...MB
MARINE...JPB
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
359 PM CST THU DEC 13 2012
.DISCUSSION...
MAIN WEATHER ISSUE IS OBVIOUSLY THE CHANCE FOR MIXED PCPN TOMORROW
NIGHT INTO SATURDAY NIGHT AS THE UPPER LOW CURRENTLY MOVING INTO
THE SOUTHWEST CONUS MAKES ITS WAY NORTH AND EAST INTO OUR AREA.
MODEL GUIDANCE HAS NOT CHANGED TOO DRAMATICALLY SINCE LAST
NIGHT... KEEPING THE GENERAL THEME OF DEVELOPING A SURFACE LOW IN
EASTERN COLORADO TOMORROW EVENING... THEN TAKING IT NORTHEAST
ACROSS IOWA SATURDAY MORNING... AND INTO SOUTHERN WISCONSIN BY
SATURDAY NIGHT. ALL OF THE SOLUTIONS STILL SUGGEST GOOD WARMING IN
THE BOTTOM 5K FT OR SO OF THE PROFILE AHEAD OF THE SYSTEM...
MAKING PCPN-TYPE ISSUES THE MAIN FORECAST CHALLENGE. THERE ARE
DIFFERENCES IN THE DEGREE TO WHICH THE MODELS WARM THINGS ALOFT...
AND EQUALLY IF NOT MORE IMPORTANT DIFFERENCES IN HOW THEY HANDLE
NEAR SURFACE TEMPERATURES. ALSO OF CONCERN IS EXACTLY HOW MUCH
PCPN WILL OCCUR... WITH THAT VARYING QUITE A BIT OVER THE WESTERN
PORTION OF THE CWFA... WHERE THE NAM AND ECMWF BOTH DEVELOP MORE
IN THE WAY OF MID-LEVEL DEFORMATION AND FRONTOGENESIS IN
COMPARISON TO THE GFS AND MANY OF THE SREF MEMBERS. WITH THE UPPER
WAVE JUST NOW COMING ONSHORE WE SHOULD SEE A BIT BETTER SAMPLING
OF ITS DETAILS WITH THE UPPER AIR NETWORK THIS EVENING... WHICH
MAY HAVE MORE OF AN IMPACT THAN IN SOME SITUATIONS GIVEN LIMITED
SATELLITE SAMPLING WHILE IT/S BEEN OFFSHORE DUE TO THE DRY
ATMOSPHERIC PROFILE WHICH HAS LIMITED GETTING MUCH VERTICAL
RESOLUTION SAMPLING OF THE TROUGH OVER THE PAST FEW DAYS. FOR
NOW... WILL NOT LATCH ONTO THE SPECIFICS OF ANY PARTICULAR
SOLUTION... AND INSTEAD GO IN LINE WITH MORE OF GFS/NAM/ECMWF
BLEND... LEANING SLIGHTLY MORE TOWARD THE GFS AT THIS POINT SINCE
ITS QPF SEEMS TO BETTER MATCH THE ANTICIPATED LARGE SCALE FORCING.
THE 12Z FIM IS ALSO FAIRLY SIMILAR TO THE GFS IN ITS HANDLING OF
THINGS.
FOR TONIGHT... WE WILL SEE THE WEAK SURFACE RIDGE TO OUR NORTHWEST
BUILD IN ACROSS THE AREA IN THE WAKE OF TODAY/S COLD FRONTAL
PASSAGE. THE WIDESPREAD STRATUS UPSTREAM HAS MADE LITTLE PROGRESS
SOUTHEAST TODAY... SO THE NIGHT AT LEAST LOOKS TO START OUT CLEAR
TO PARTLY CLOUDY. HOWEVER... WITH DEWPOINTS STILL IN THE 20S
ACROSS MUCH OF THE AREA... AND WITH SOME ADDITIONAL MELTING HAVING
OCCURRED AT LEAST OVER THE SOUTH AND EAST... WOULD EXPECT TO SEE
AREAS OF FOG AND SOME STRATUS TO DEVELOP IN SITU TONIGHT. WHATEVER
DEVELOPS SHOULD BE MOVED OUT RATHER QUICKLY TOMORROW AS FAIRLY
ROBUST WARM ADVECTION GETS GOING DURING THE MORNING AND EARLY
AFTERNOON AHEAD OF THE NEXT SYSTEM. THE 300K ISENTROPIC SURFACES
FROM THE NAM AND GFS HAVE DECENT WARM ADVECTION THROUGH THE
EVENING... BUT DON/T APPEAR TO LOWER CONDENSATION PRESSURE
DEFICITS ENOUGH FOR PCPN UNTIL AFTER 06Z FOR MOST OF THE AREA...
AND PARTICULARLY BY 12Z SATURDAY. AT THAT POINT... 925MB
TEMPERATURES LOOK TO BE ABOVE FREEZING OVER MOST OF THE AREA...
WITH 850MB TEMPERATURE ABOVE FREEZING OVER THE ENTIRE AREA. WE
WILL BE MOISTENING THROUGH THE DEPTH OF THE COLUMN RATHER QUICKLY
SATURDAY MORNING... SO WOULD EXPECT WHAT IS INITIALLY TO BE LIGHT
PRECIPITATION TO BECOME SOMEWHAT HEAVIER AROUND AND AFTER 12Z.
WITH TEMPERATURES ALOFT EXPECTED TO BE ABOVE FREEZING OVER THE
ENTIRE AREA... WE WILL BE LOOKING AT THE POTENTIAL FOR WIDESPREAD
SLEET AND/OR FREEZING RAIN. 2M TEMPERATURES OVER THE SOUTHERN CWFA
LOOK TO BE ABOVE ZERO AT THAT POINT... WHICH MAY ALSO BE IN THE
CASE IN THE TWIN CITIES METRO... BUT MOST OTHER LOCATIONS SHOULD
STILL BE BELOW FREEZING... WHICH COULD MAKE FOR SEVERAL HOURS OF
MESSY CONDITIONS BEFORE LOW LEVEL TEMPERATURES CLIMB ABOVE
FREEZING DUE TO CONTINUED WARM ADVECTION FROM EAST AND SOUTHEAST
FLOW. THE FAR WEST AND NORTHWEST CWFA ALSO LOOKS LIKE IT WILL HAVE
ABOVE FREEZING TEMPERATURES ALOFT SATURDAY MORNING... BUT PERHAPS
NOT QUITE AS WARM... SO THEY COULD SEE A BIT MORE IN THE WAY OF
SLEET VS FREEZING RAIN. HOWEVER... PCPN AMOUNTS IN THAT AREA MAY
BE LIMITED DEPENDING UPON WHETHER THINGS WINDS UP MORE LIKE THE
GFS/FIM OR LIKE THE NAM/ECMWF.
LARGE SCALE FORCING FOR THE SATURDAY SYSTEM LOOKS A BIT TRICKY...
SINCE IT IS NOT GOING TO BE A PHASED NORTHERN/SOUTHERN STREAM
SHORTWAVE TROUGH... BUT A SOUTHERN STREAM WAVE LIFTING NORTHEAST
INTO THE PREVAILING UPPER RIDGE. THIS WILL MAKE IT DIFFICULT FOR
IT TO ESTABLISH ANY PERSISTENT AREA OF MID-LEVEL DEFORMATION
NORTHWEST OF THE SURFACE LOW... AND MOST OF THE UPPER DIVERGENCE
ASSOCIATED WITH ITS UPPER JET WILL PUSH EAST OF OUR AREA VERY
QUICKLY ON SATURDAY. THE 850-500MB Q-VECTOR CONVERGENCE FROM THE
NAM SUGGESTS THIS AS WELL... PUSHING MOST OF THE FORCING ACROSS
OUR AREA EARLY SATURDAY MORNING... THEN SUGGESTING WEAK FORCING
AND EVEN SOME SUBSIDENCE BY LATER IN THE DAY. IT DOES HANG ONTO
SOME FORCING ACROSS THE WEST... WHERE IT ALSO INDICATES AND AREA
OF 850-700MB FRONTOGENESIS ASSOCIATED WITH THE SECONDARY PCPN AREA
IT DEPICTS. HOWEVER... FEEL IT IS TOO EARLY TO BUY INTO THAT
MESOSCALE FEATURE... PARTICULARLY WITH THE GFS... FIM... AND MANY
OF THE SREF MEMBERS NOT DOING SO. THE THALER-QG DIAGNOSTICS FOR
THE NAM... WHICH MAINLY CONSIDER THE OVERALL LARGE SCALE
FORCING... SHOW A MUCH SIMILAR PATTERN OF VERTICAL MOTION AS THE
GFS DOES... AND HAVE SIMILAR QG-INDUCED NORTHWEST-SOUTHEAST PCPN
GRADIENT AS THE FULL SOLUTION OF THE GFS. WITH WARM TEMPERATURES
ALOFT LOOKING TO LIMIT SNOWFALL POTENTIAL FOR FRIDAY NIGHT AND
MUCH OF SATURDAY... THE MAIN CONCERN BECOMES FREEZING
PRECIPITATION AS WELL AS SOME POTENTIAL FOR SLEET. IT IS LIKELY
THAT A WINTER WEATHER ADVISORY WILL BE ISSUED AT SOME POINT LATER
TONIGHT OR FRIDAY MORNING TO ACCOUNT FOR THE MIXED PCPN
POTENTIAL... BUT AT THIS POINT THE LOCATION... TIMING... AND
AMOUNTS ARE TOO UNCERTAIN TO ISSUE ANYTHING. AND... THE MAGNITUDE
IS ALSO IN QUESTION... WITH THE LOCATIONS MOST LIKELY TO SEE A
LONGER DURATION OF FZRA/IP ALSO LOOKING LIKE THEY WILL RECEIVE
LOWER AMOUNTS OF PCPN. THE PRIMARY THREAT WILL LIKELY BE WITH THE
INITIAL SURGE OF PCPN THAT LIFTS NORTHEAST THROUGH THE AREA
SATURDAY MORNING AHEAD OF THE UPPER WAVE IN THE INITIAL AREA OF
UPPER DIVERGENCE AND DPVA... MAKING THE THERMAL PROFILE AND AMOUNT
OF PCPN THAT OCCURS AT THAT TIME THE KEY ISSUES. THOSE FACTORS
SHOULD BECOME BETTER DEFINED WITH TONIGHT/S NUMERICAL GUIDANCE. AT
THIS POINT... ALL BUT THE SOUTHERN PORTION OF THE AREA SHOULD AT
LEAST PREPARE FOR A PERIOD OF SOME FREEZING RAIN AND/OR SLEET WITH
SOME ACCUMULATION OF ICE POSSIBLE FROM LATE TONIGHT INTO SATURDAY
MORNING.
SATURATION AND SOME DYNAMIC COOLING ASSOCIATED WITH THE PV ANOMALY
MOVING NEARBY SHOULD ALLOW FOR THE PROFILE TO COOL DURING THE
AFTERNOON AND INTO THE EVENING HOURS... ALLOWING PCPN TO
TRANSITION BACK TO SNOW. HOWEVER... BEFORE THAT OCCURS... THERE
CERTAINLY COULD BE A PERIOD OF LIGHT RAIN ACROSS A GOOD PART OF
THE SOUTHERN AND EASTERN PORTION OF THE AREA FROM LATE SATURDAY
MORNING INTO THE AFTERNOON. ONCE THINGS TRANSITION TO SNOW WE WILL
ALREADY BE ON THE BACKSIDE OF THE UPPER WAVE AND WITH IT QUICKLY
EJECTING NORTHEAST IT DOESN/T APPEAR WE WILL KEEP MUCH OF A
COMBINATION OF MOISTURE AND FORCING AROUND FOR LONG. SO... ANY
SNOW ACCUMULATIONS LOOK TO BE FAIRLY LIMITED AT THIS POINT...
TYPICALLY UNDER THREE INCHES. HOWEVER... SHOULD WE NOT WARM AS
MUCH AS ANTICIPATED INITIALLY... THEN SOME OF THE EARLY PCPN COULD
FALL AS SNOW AND THE TRANSITION BACK TO SNOW WOULD OCCUR SOONER...
WHICH COULD BOOST THOSE TOTAL SOME. BUT... WITH OVERALL LIQUID PCPN
EXPECTED TO RANGE FROM 0.10-0.50... IT WILL BE TOUGH FOR ANYONE TO
SEE MUCH MORE THAN 4 OR 5 INCHES EVEN IF THEY WERE SOMEHOW ABLE TO
STAY ALL SNOW. CURIOUSLY... NORTHERN PORTION OF THE WEST CENTRAL
WISCONSIN COUNTIES AND THE NORTH CENTRAL PORTION OF THE CWFA LOOK
LIKE THEY MAY SEE THE COOLEST PROFILE FOR MUCH OF THE EVENT...
MAKING THOSE AREAS THE MOST LIKELY TO SEE THE GREATER SNOW IF IT
IS A BIT COOLER THAN EXPECTED AND/OR MORE SUBSTANTIAL FZRA/IP
SHOULD WE BE ON THE WARMER END OF THINGS.
A WEAK RIDGE OF HIGH PRESSURE WILL BUILD INTO THE AREA ON
SUNDAY... WITH COOLER BUT CERTAINLY NOT COLD TEMPERATURES. NEAR TO
ABOVE NORMAL TEMPERATURES THEN LOOK TO REIGN THROUGH THE WEEK...
WITH THE NEXT CHANCE FOR MORE WIDESPREAD PCPN HOLDING OFF UNTIL
THE MIDDLE TO LATTER HALF OF THE WEEK AS ANOTHER SYSTEM DEVELOPS
IN THE LEE OF THE ROCKIES AND LIFTS NORTHEAST TOWARD THE GREAT
LAKES. THE GFS AND ECMWF ARE ACTUALLY IN DECENT AGREEMENT AT THIS
POINT... AND BOTH HAVE A TRACK WHICH WARRANTS KEEPING AN EYE ON
THINGS... SINCE WE WOULD BE UNDER OR NEAR THE PCPN SWATH
ASSOCIATED WITH IT. AT THIS POINT... THIS SYSTEM ALSO APPEARS TO
BE BETTER PHASED WITH THE NORTHERN STREAM AND RESERVOIR OF COLD
AIR TO OUR NORTH... PERHAPS MAKING PCPN-TYPE LESS OF AN ISSUE IF
AT ALL.
&&
.AVIATION.../18Z TAF ISSUANCE/
/ISSUED 1145 AM CST THU DEC 13 2012/
COLD FRONT EXITING SLOWLY TO THE EAST THIS AFTERNOON. BAND OF MVFR
CLOUDS BEHIND THE FRONT...BKN AT THE MOMENT AND HIGHER CLOUDS TO
THE NORTH. MODELS CONTINUE TO INDICATE FURTHER DEVELOPMENT TO THE
SOUTH AND WEST DURING THE AFTERNOON. WILL TREND TO MVFR OVER THE
SOUTHERN AND EASTERN SITES THIS AFTERNOON. AM UNCERTAIN ONTO HOW
QUICKLY AND HOW MUCH CLOUDS WILL REMAIN INTO THE NIGHT. VARIOUS
PROG CHARTS INDICATE MAINTAIN MVFR CONDITIONS THROUGH THE NIGHT.
LATEST RAP DOES SHOW THIS AS WELL. WILL HOLD ONTO THE MVFR AND
LOWER SOME INTO THE NIGHT...GOING IFR TO THE NORTH AS IN THE
PREVIOUS FORECAST. WILL ALSO INCLUDE SOME MVFR VSBYS IN FOG IF WE
RETAIN CLOUDS OVERNIGHT. LIGHT NORTH/NORTHWEST WIND THIS
AFTERNOON...LIGHT/VRBL OVERNIGHT BECOMING EAST SOUTHEAST AHEAD OF
DEVELOPING LOW PRESSURE SYSTEM FRIDAY.
KMSP...MODELS CONTINUE TO SUGGEST AT LEAST BKK025 MOVING INTO THE
PICTURE THIS AFTERNOON. WILL MENTION THAT AFTER 21Z. ALSO WILL
MAINTAIN LOW CLOUDS INTO TONIGHT AFTER COLLABORATION WITH VARIOUS
PARTNERS. THIS SHOULD EVENTUALLY LIFT NORTH AND WEST AGAIN INTO
FRIDAY AS LOW LEVEL FLOW BECOMES MORE SOUTHEAST. SURFACE WINDS WILL
REMAIN NORTH/NORTHWEST AND LIGHT THIS AFTERNOON WITH THE MORE EAST
SOUTHEAST FLOW INTO FRIDAY. ANY PRECIPITATION WILL HOLD OFF UNTIL
LATER FRIDAY NIGHT.
/OUTLOOK FOR KMSP/
FRI NIGHT...MVFR CONDS DEVELOPING LATE. SE WIND 5-10 KT.
SAT...IFR/MVFR CONDS LIKELY IN RA/SN/ZR...E TO NE WIND 5-10 KT.
SUN...IFR/MVFR CONDS EARLY...SLOW IMPROVEMENT DURING THE DAY. NW
WIND 5-10 KT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$