Forecast Discussions mentioning any of
"HRRR" "RR" "RUC13" "RUC" received at GSD on 02/13/12
AREA FORECAST DISCUSSION
NWS NEW YORK NY
955 AM EST SAT FEB 11 2012
.SYNOPSIS...
DEVELOPING LOW PRESSURE OFF THE MID ATLANTIC COAST THIS MORNING WILL
PASS WELL SOUTHEAST OF LONG ISLAND THIS AFTERNOON. A STRONG COLD
FRONT WILL FOLLOW LATE TODAY INTO THIS EVENING... FOLLOWED BY A
SECOND COLD FRONT SUNDAY AFTERNOON AND EVENING. HIGH PRESSURE WILL
THEN GRADUALLY BUILD FROM THE CENTRAL PLAINS TO THE MID ATLANTIC
COAST THROUGH EARLY NEXT WEEK. A WEAK FRONTAL BOUNDARY NEARBY WILL
APPROACH ON TUESDAY AND LIFT TO THE NORTH. HIGH PRESSURE WILL THEN
BUILD BACK IN FOR THE REST OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATEST RADAR AND SATELLITE TRENDS CONTINUE TO INDICATE THAT THE
BULK OF THE HEAVIER SNOW WILL STAY TO OUR EAST...WITH OCCASIONAL
MODERATE SNOWFALL CLIPPING THE EAST END OF THE TWIN FORKS AND FAR
EASTERN NEW LONDON COUNTY. TO THE WEST A GENERAL LIGHT SNOW...WITH
PERIODIC BREAKS SHOULD CONTINUE THROUGH AT LEAST LATE
MORNING...THEN TAPER OFF FROM WEST TO EAST IN THE AFTERNOON.
GENERALLY LOOKING AT UNDER AN INCH AT MOST LOCATIONS...BUT COULD
SEE 1-2 INCHES ON EASTERN PORTIONS OF THE TWIN FORKS AND FAR
EASTERN NEW LONDON COUNTY...PLUS SOME ISOLATED 1-2 INCH AMOUNTS
IN HIGHER ELEVATIONS FROM WESTCHESTER COUNTY ON EAST.
THE STORM CONTINUES TO BASICALLY TRACK EAST FROM THE NC OUTERBANKS
IN RESPONSE TO A SOUTHERN STREAM SHORTWAVE THAT IS NOW JUST SOUTH
OF CAPE LOOKOUT NC. THIS SHORTWAVE FINALLY PIVOTS NE THIS
AFTERNOON...BUT TOO LATE FOR THE COASTAL LOW TO HAVE ANYMORE
IMPACT THAN ABOVE. AN ARGUMENT COULD BE MADE THAT WHAT IS REALLY
DRIVING OUR SNOWFALL IS NOT THE COASTAL LOW/SOUTHERN STREAM
SHORTWAVE AT ALL...BUT LOW TO MID LEVEL BAROCLINICITY OUT AHEAD OF
THE ARCTIC AIRMASS HEADING OUR WAY. WILL ALSO GET A LITTLE
ENHANCEMENT LATE THIS MORNING/EARLY THIS AFTERNOON FROM THE LEFT
EXIT REGION OF A 100 KT 250 HPA JET STREAK.
TEMPERATURE FORECAST WAS RUNNING A TAD HIGH...ADJUSTED DOWN A FEW
DEGREES TO A BLEND OF LAV/MET GUIDANCE WITH NAM AND HRRR 2-METER
TEMPERATURES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
STRONG COLD FRONT AND H5 TROUGH AXIS PASS THROUGH LATE THIS
AFTERNOON/EARLY THIS EVENING...ACCOMPANIED BY ISOLD/SCT SNOW SHOWERS
THAT COULD LEAVE AN ADDITIONAL QUICK COATING OF ACCUMULATION.
STRONG CAA AND A TIGHTENING PRES GRADIENT AS THE OFFSHORE LOW
STRENGTHENS WILL INCREASE OUR WINDS THROUGH THE NIGHT.
UPPER TROUGH AXIS EXPECTED TO BE E OF THE AREA BY SUN MORNING.
COULD SEE SOME SNOW SHOWERS OR SNOW SQUALLS IN THE AFTERNOON AND
EARLY EVENING WITH APPROACH/PASSAGE OF AN ARCTIC COLD FRONT.
FCST SOUNDINGS SHOW NEARLY ADIABATIC LAPSE RATES UP TO 750 MB...
SO A BRIEF GUST TO 40-45 MPH AND EVEN A RUMBLE OF THUNDER IN ANY
SNOW SHOWERS/SQUALLS CANNOT BE TOTALLY RULED OUT.
LOW CHANCE OF LAKE EFFECT SHOW SHOWERS MAKING TO WESTERN ZONES ON
SUNDAY...THOUGH DOWNSLOPING EFFECTS MAY MAKE IT DIFFICULT FOR
PRECIP TO MAKE IT OVER THE MOUNTAINS.
QUITE COLD SAT NIGHT THROUGH SUNDAY NIGHT...WITH LOWS IN THE TENS
TO LOWER 20S...AND HIGHS ONLY 30-35 ON SUNDAY. PRES GRADIENT WILL
REMAIN TIGHT BETWEEN DEPARTING LOW PRES TO THE NE AND HIGH PRES
BUILDING OVER THE OH VALLEY...WITH CONTINUED GUSTY WINDS THROUGH
SUNDAY EVENING...DIMINISHING LATE SUNDAY NIGHT.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
FAIR WX AND A RETURN TO NEAR AVG TEMPS EXPECTED ON MON...WITH HIGH
PRES PASSING TO THE S AND AN ARCTIC COLD FRONT RETREATING NE.
UPPER PATTERN GENERALLY ZONAL THROUGH MOST OF THE WEEK WITH A FEW
WEAK SHORTWAVES EMBEDDED IN THE FLOW. THE FIRST LOOKS TO BE ON
TUE/TUE NIGHT AND THE SECOND WED/WED NIGHT. EVAPORATIONAL COOLING
EFFECTS MAY RESULT IN A LIGHT SNOWFALL EVENT ON TUE...BUT IT
ATMOSPHERIC PROFILES LOOK WARMER FOR WED.
THE 12Z EC IS ALSO INDICATING THE POSSIBILITY OF A MORE SIGNIFICANT
STORM LATE NEXT WEEK. SOLUTIONS HAVE BEEN VARYING WITH THIS SYSTEM
FOR THE LAST FEW DAYS...SO HAVE KEPT IT DRY FOR NOW.
LONG TERM TEMPS ARE EXPECTED TO REMAIN ABOVE NORMAL EXCEPT FOR A
BRIEF COLD SNAP ON SUN WHERE TEMPS WILL BE AROUND 10 DEGREES BELOW
CLIMATOLOGICAL NORMS.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
LOW PRES WILL PASS SE OF LONG ISLAND TODAY. LIGHT TO OCCASIONALLY
MODERATE SNOW WILL PRODUCE MVFR TO IFR CIGS/VSBYS OVER THE TERMINALS
INTO EARLY THIS AFTERNOON. CONDITIONS THEN IMPROVE TO VFR.
ARCTIC FRONT PASSES THROUGH THE REGION EARLY THIS EVENING. A BRIEF
PERIOD OF SNOW IS POSSIBLE WITH ITS PASSAGE...AND WILL INTRODUCE A
TEMPO GROUP AROUND ITS PASSAGE WITH THE 15Z TAF AMENDMENT PACKAGE TO
REFLECT THIS RISK.
AS THE LOW CONTINUES TO DEEPEN EAST OF THE AREA GUSTY NORTHWEST TO
NORTH WINDS WILL DEVELOP. SUSTAINED WINDS WILL BE AROUND 15 KT WITH
GUSTS UP TO 30 KT LIKELY...BEFORE INCREASING TO 20-25 KT WITH 30-35
KT GUSTS.
OUTLOOK FOR 15Z SUNDAY THROUGH WEDNESDAY...
SUNDAY...VFR. NW WINDS AROUND 310 TRUE AT 15-20 KT WITH 20-25 KT
GUSTS...BACKING TO THE LEFT OF 310 TRUE IN THE AFTERNOON.
SUNDAY NIGHT...VFR WITH DIMINISHING WEST WINDS.
MONDAY...VFR WITH GUSTY NW WINDS.
TUESDAY THROUGH WEDNESDAY...SUB VFR-POSSIBLE IN SCT LIGHT SNOW
TUESDAY AND RAIN AND SNOW WEDNESDAY.
&&
.MARINE...
SEAS RUNNING ABOUT A FOOT LOWER THAN FORECAST LEVELS...SO LOWERED
SEAS ON THE OCEAN WATERS A FOOT TO GET STARTED - BUT STILL A FOOT
ABOVE WAVEWATCH III GUIDANCE.
EXPECT QUIET CONDITIONS TODAY WITH MAINLY LIGHT
N-NE FLOW IN THE WAKE OF LOW PRES PASSING WELL TO THE SE.
TONIGHT...WINDS AND SEAS INCREASE. HAVE CONVERTED THE GALE WATCH TO
A GALE WARNING THE OCEAN WATERS. GUSTS TO 35 KT WILL BE LIKELY WITH
STRONG GUSTY WINDS ON COLD AIR ADVECTION. FOR THE REMAINDER OF THE
WATERS...HAVE HOISTED A SMALL CRAFT ADVISORY WHERE GUSTS WILL BE
LESS LIKELY. THERE DOES HOWEVER REMAIN A CHANCE THAT SOME GUSTS
REACH GALE FORCE. WINDS AND SEAS SLOWLY SUBSIDE ON MONDAY WITH SCA
CONDITIONS LIKELY THROUGH MON MORNING. OCEAN SEAS WILL TAKE LONGER
TO SUBSIDE...SO MAY NEED SCA THERE INTO MON NIGHT.
&&
.HYDROLOGY...
LIQUID EQUIVALENT QPF WITH THE ONGOING EVENT NOW LESS THAN 1/10
INCH NW OF NYC...AND 1/10 TO 1/4 INCH ELSEWHERE. NO SIGNIFICANT
PRECIPITATION EXPECTED EARLY NEXT WEEK.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 PM EST SUNDAY
FOR ANZ330-335-338-340-345.
GALE WARNING FROM 6 PM THIS EVENING TO 6 PM EST SUNDAY FOR
ANZ350-353-355.
&&
$$
SYNOPSIS...BC/GOODMAN
NEAR TERM...GOODMAN/MALOIT
SHORT TERM...GOODMAN
LONG TERM...GOODMAN/24
AVIATION...MPS
MARINE...BC/MALOIT
HYDROLOGY...GOODMAN
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
858 PM EST SUN FEB 12 2012
.SYNOPSIS...
HIGH PRESSURE WILL BUILD TOWARD THE REGION TONIGHT...THEN PASS SOUTH
OF THE AREA MONDAY INTO TUESDAY. A WARM FRONT WILL APPROACH THE AREA
TUESDAY EVENING...THEN LOW PRESSURE WILL DEVELOP ON THE FRONT AND
MOVE EAST OF THE AREA WEDNESDAY. HIGH PRESSURE WILL BUILD IN BEHIND
THE FRONT FOR THURSDAY...THEN MOVE OFFSHORE THURSDAY EVENING. ANOTHER
WARM FRONT WILL APPROACH THE REGION LATER THURSDAY EVENING. LOW PRESSURE
WILL DEVELOP ON THE FRONT LATE THURSDAY NIGHT BEFORE ITS MOVES INTO
NEW ENGLAND FRIDAY. A COLD FRONT WILL BRING COLDER WEATHER NEXT
WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
THE RESIDUAL LAKE EFFECT BANDS OF SNOW SHOWERS AND FLURRIES ACROSS
THE CENTRAL PART OF OUR CWA ARE STARTING TO RUN ON FUMES. THIS
SEEMS CONSISTENT WITH THE RECENT HRRR RUNS, THE WRF-NMMB INCREASING
THE SHEAR BELOW 850MB AND THE SUBSIDENCE INVERSION LOWERING. SO WE
PRETTY MUCH ARE NOT EXTENDING THAT MENTION OF FLURRIES AND SNOW
SHOWERS MUCH BEYOND 03Z. WE DID EXTEND THE MENTION OF FLURRIES IN
THE POCONOS SLIGHTLY LONGER, BUT EVEN THERE ONE SPOTTER TOLD US HE
IS STARTING TO SEE STARS NOW.
THE 00Z UA ANALYSIS IS SHOWING THAT THE THERMAL TROF IS THROUGH
AND WITH WINDS EXPECTED TO REMAIN UP THROUGH THE NIGHT, DID NOT
CHANGE MIN TEMPS MUCH. CLOUDINESS A BIT MORE PROBLEMATICAL AS IT
IS DISSIPATING AS IT MOVES EAST. SO CONFIDENCE ABOUT THOSE GRIDS
ARE NOT AS HIGH AS OTHER WEATHER ELEMENTS OVERNIGHT.
THE STRONG NORTHWEST FLOW IS EXPECTED TO DIMINISH SOME THIS EVENING
AND INTO THE OVERNIGHT AS THE PRESSURE GRADIENT SLACKENS AS LOW
PRESSURE CONTINUES TO MOVE WELL INTO NORTHERN CANADA. WINDS MAY
REMAIN GUSTY OVERNIGHT, BUT THE STRENGTH IS EXPECTED TO DROP.
OTHERWISE, ANOTHER COLD NIGHT CAN BE EXPECTED, WITH TEMPERATURES
EXPECTED TO BE A FEW DEGREES BELOW NORMAL, BUT FEEL NOT QUITE AS
COLD AS LAST NIGHT WITH WINDS DIMINISHING.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
HIGH PRESSURE IS EXPECTED TO CONTINUE TO BUILD TO OUR SOUTH ON
MONDAY, GIVING US MORE OF A WESTERLY FLOW AT THE SURFACE, WHILE THE
FLOW ALOFT BECOMES MORE WESTERLY AS WELL. THIS SHOULD CUT OFF THE
STRONG LAKE EFFECT FLOW FOR OUR AREA, AND WITH NO SHORT WAVES/VORT
MAXES EXPECTED, WE DO NOT ANTICIPATE ANY PRECIPITATION AT THIS TIME.
THICKNESSES AND 925 MB TEMPERATURES WILL BE ON THE RISE MONDAY, SO
TEMPERATURES WILL BE WARMER THAN TODAY, BUT STILL MAY BE A COUPLE OF
DEGREES BELOW NORMAL.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
IT LOOKS LIKE THERE WILL BE TWO SYSTEMS WITH PRECIPITATION CHANCES
DURING THIS PERIOD. THE PERIOD STARTS FAIRLY WARM...BUT COOLS DOWN
FOR THE UPCOMING WEEKEND.
ANY LEFTOVER CUMULUS OR STRATOCUMULUS SHOULD MELT AWAY MONDAY
EVENING. THE GRADIENT SHOULD ALSO BACK OFF...AS HIGH PRESSURE DUCKS
TO THE SOUTH OF THE AREA. WINDS MAY NOT GO CALM...AS THE THERE MAY
BE JUST ENOUGH OF A WESTERLY FLOW TO PREVENT THIS. CLEAR SKIES IN
THE EVENING WILL GIVE WAY OF INCREASING HIGH AND EVENTUALLY MID
LEVEL CLOUDS AHEAD OF A NORTHERN STREAM SHORT WAVE. THE COMBINATION
OF CLOUDS AND WIND SHOULD PREVENT A GOOD RADIATIONAL COOLING
NIGHT...AND LOWS WERE GENERALLY BASED ON A MOS BLEND.
THE WARM AIR ADVECTION AHEAD OF THE SHORT WAVE TUESDAY WILL GO INTO
MOISTENING THE COLUMN...AND THE 1200 UTC GFS APPEARS TO BE TOO
AGGRESSIVE BRINGING PRECIPITATION INTO THE INITIALLY DRY AIR. AS
SUCH...MUCH OF THE DAY SHOULD BE DRY. WINDS WILL START TO BACK AHEAD
OF A SURFACE WARM FRONT SNAKING EAST FROM THE LOWER OHIO VALLEY.
THIS COULD KEEP COASTAL WATERS FROM WARMING...BUT ELSEWHERE HIGHS
WERE GENERALLY BASED ON A MOS BLEND.
WHILE THE MASS FIELDS FOR THE SHORT RANGE MODELS ARE FAIRLY
CLOSE...THE 1200 UTC IS FLATTER AND WEAKER WITH THE SURFACE WAVE
TUESDAY NIGHT. THE WARM AIR ADVECTION IS IMPRESSIVE (WITH A 35 KNOT
LOW LEVEL JET LATE TUESDAY NIGHT?)...BUT IS IT UNCLEAR JUST HOW MUCH
OF THIS WILL GO INTO PRECIPITATION PRODUCTION. FOR NOW...THE BEST
CHANCE OF PRECIPITATION WAS LIMITED TO NORTHERN AREAS...WITH THE
BEST OVERRUNNING POTENTIAL
THE COLUMN IS COLD THROUGH MUCH THE WARM AIR ADVECTION AND
OVERRUNNING...BUT A WARMING BOUNDARY LAYER MAY CAUSE SOME
PRECIPITATION TYPE FORECAST PROBLEMS. AGAIN...IT IS UNCLEAR JUST HOW
IN THE WAY OF PRECIPITATION WILL OCCUR TUESDAY NIGHT...BUT ACROSS THE
HIGHER TERRAIN THIS COULD BE LIGHT SNOW. LOWS WERE GENERALLY BASED
ON THE WARMER NAM MOS NUMBERS.
A SURFACE WAVE LOOKS TO FORM ON THE FRONT WEDNESDAY MORNING...AS THE
MID LEVEL SHORT WAVE PASSES TO THE NORTH. THE BEST DEEPENING SHOULD
OCCUR WELL TO THE NORTHEAST OF THE REGION (AS HAS BEEN THE CASE MOST
OF THE COOL SEASON). THUS...THE BEST CHANCE OF PRECIPITATION WILL BE
IN THE MORNING. THE GRADIENT COULD INCREASE ENOUGH ON THE BACK SIDE
OF THE LOW TO ALLOW WEST TO NORTHWEST WINDS TO BECOME GUSTY IN THE
AFTERNOON...AND THIS COULD ALSO AID IN CLEARING.
AFTER A DRY WEDNESDAY NIGHT AND THURSDAY...THE SECOND PRECIPITATION
EVENT STARTS TO DEVELOP. THE WARM AIR ADVECTION IN THIS EVENT
APPEARS TO BE STRONGER AND BETTER ORGANIZED...AGAIN WITH THE WARM
FRONT AS THE FOCUS. UNLIKE TUESDAY NIGHT...HOWEVER...THE COLUMN WILL
BE IN THE PROCESS OF WARMING...AND THIS SHOULD ULTIMATELY LIMIT
WINTRY PRECIPITATION TO NORTHWEST AREAS AND THE HIGHER TERRAIN. THE
MAIN HOLDOUT IN THIS SCENARIO IS THE 1200 ECMWF...WHICH IS SLOWER
WITH THE MAIN PUNCH OF WARM AIR ADVECTION AND COULD BE SLOWER TO
WARM THE COLUMN.
AT ANY RATE...THE HIGHEST QPF POTENTIAL APPEARS TO FOCUS ON THE WARM
FRONT...WITH LESS THAN ONE-HALF INCH OF QPF FOR AREAS THAT COULD BE
COLD ENOUGH AT THE START FOR WINTRY PRECIPITATION. RIGHT NOW...THIS
DOES NOT LOOKS TO BE A SIGNIFICANT WINTER WEATHER EVENT FOR THE AREA.
THE PRECIPITATION WILL WIND DOWN FRIDAY MORNING AS LOW PRESSURE
DEVELOPS ON THE FRONT...IN RESPONSE TO YET ANOTHER NORTHERN STREAM
MID LEVEL SHORT WAVE.
THE PATTERN LOOKS TO CHANGE TO COLDER WEATHER FOR THE UPCOMING
WEEKEND AS THE LONG WAVE TROUGH POSITION MOVES INTO THE EASTERN
UNITED STATES. HOWEVER...THIS LOOKS TRANSITORY...AS HEIGHTS START TO
RISE IN THE WAKE OF THE EXITING MID LEVEL TROUGH.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
VFR FORECAST WILL BE ISSUED WITH THE LATEST TAFS. WINDS WILL
REMAIN GUSTY INTO THIS EVENING AS FORECAST SOUNDINGS ARE
SUGGESTING 30 PLUS KNOT WIND GUSTS STILL POSSIBLE. THE SUGGESTED
GUSTS HAVE BEEN RUNNING A BIT HOT, SO WE WERE NOT AS ROBUST AS
THEIR SUGGESTIONS. WE KEPT A TRANSITION ZONE OF WEAKER WIND GUSTS
LATER THIS EVENING BEFORE DROPPING THEM OVERNIGHT.
AS FAR AS THE VFR CIGS GO, THE TREND TOWARD LESS IS CONTINUED THIS
EVENING LINGERING IT THE LONGEST AT KABE AND THEN KRDG AND KTTN.
THE DEVELOPING FORECAST INVERSION WE BELIEVE WILL NOT BE STRONG
ENOUGH TO TRAP A VFR CIG BELOW IT AT THE TAF SITES OVERNIGHT.
ON MONDAY VFR CONDITIONS ARE FORECAST TO CONTINUE. THE LATEST
SOUNDING FORECAST CONVECTIVE TEMPERATURES ARE TOO HIGH TO DEVELOP
ANY HOME GROWN CUMULUS OR STRATOCUMULUS. WE CARRIED A BIT OF
CIRRUS ASSOCIATED WITH THE NEXT SYSTEM EXITING THE ROCKIES. WINDS
WILL INCREASE AGAIN ONCE THE SUN RISES AND MIXING STARTS AGAIN.
WHILE IT WILL BE WINDY, PEAK WIND GUSTS SHOULD BE DOWN FROM
TODAY, GENERALLY BETWEEN 20 AND 25 KNOTS. THE GUSTINESS WITH THIS
EVENT SHOULD BE GONE FOR GOOD ONCE THE SUN SETS AS PER THE 30HR
KPHL TAF.
OUTLOOK...
MONDAY NIGHT LOOKS VFR. HIGH AND EVENTUALLY MID LEVEL CLOUDINESS
WILL INCREASE MONDAY NIGHT AND CONTINUE INTO TUESDAY MORNING.
VFR CONDITIONS ARE EXPECTED TUESDAY AS A WARM FRONT APPROACHES. IT
IS NOT CLEAR JUST HOW MUCH PRECIPITATION WILL OCCUR WITH THE
FRONT...AND FOR NOW IT APPEARS AS THOUGH CONDITIONS MAY DROP TO MVFR
TUESDAY NIGHT AS THE FRONT BISECTS THE AREA. IF PRECIPITATION DOES
DEVELOP...LOCAL IFR CONDITIONS ARE POSSIBLE...BUT THIS LOOKS LIKE A
LONG SHOT.
CONDITIONS WILL IMPROVE WEDNESDAY AS LOW PRESSURE DEVELOPS ON THE
FRONT AND MOVES NORTHEAST. HIGH PRESSURE WILL BRING VFR CONDITIONS
LATE WEDNESDAY INTO THURSDAY AFTERNOON. WINDS COULD GUST TO 25 KNOTS
FROM THE WEST NORTHWEST AT TIMES WEDNESDAY EVENING...BUT THIS LOOKS
LIKE A 3 TO 6 HOUR POSSIBILITY AT MOST.
ANOTHER WARM FRONT WILL APPROACH THURSDAY. CONDITIONS COULD DROP TO
MVFR AHEAD OF THE FRONT...AS WINDS ASSUME PRE WARM FRONTAL
DIRECTIONS. MOST MID RANGE MODELS SUGGEST THERE IS A BETTER CHANCE
OF PRECIPITATION WITH THIS WARM FRONT...AND MVFR CONDITIONS ARE
EXPECTED. THERE IS A CHANCE FOR IFR CONDITIONS...ESPECIALLY IF LOW
PRESSURE FORMS ON THE FRONT LATER THURSDAY NIGHT...AND THIS COULD
CONTINUE INTO FRIDAY MORNING.
AS THE LOW PULLS AWAY FRIDAY MORNING...VFR CONDITIONS ARE EXPECTED
TO RETURN. WEST TO NORTHWEST WINDS COULD GUST TO 25 TO 30 KNOTS AT
TIMES FRIDAY AS THE GRADIENT TIGHTENS DURING THE MORNING.
&&
.MARINE...
WE HAVE DECIDED TO LEAVE THE GALE WARNING UP AT LEAST INTO THE
EVENING HOURS SINCE WINDS ARE STILL GUSTING IN THE LOW 30S ACROSS
THE LAND AND AT A FEW BUOYS. FORECAST SOUNDINGS ARE SUGGESTING
GALE FORCE GUSTS REMAIN POSSIBLE THROUGH MIDNIGHT. ONCE THE GALE
WARNING GETS CANCELLED OR IS ALLOWED TO EXPIRE, A SMALL CRAFT
ADVISORY WILL REPLACE IT. ONCE A SMALL CRAFT ADVISORY IS ISSUED,
IT WILL LIKELY CONTINUE INTO THE DAY ON MONDAY AS WINDS ARE STILL
EXPECTED TO GUST AROUND 25-30 KNOTS, ALTHOUGH WINDS ARE EXPECTED
TO DIMINISH LATE IN THE DAY MONDAY.
THE GRADIENT FLOW WILL BE SLACKENING MONDAY EVENING...AS THE SURFACE
HIGH BUILDS TOWARD THE REGION. WINDS COULD BE CLOSE TO SMALL CRAFT
VALUES IN GUSTS MONDAY EVENING.. EVEN THIS BACKS OFF LATER MONDAY
NIGHT AND SUB SMALL CRAFT CONDITIONS ARE EXPECTED INTO TUESDAY
EVENING.
A WARM FRONT WILL APPROACH THE WATERS TUESDAY NIGHT. IT IS NOT CLEAR
WHETHER THE FRONT ACTUALLY GETS NORTH OF THE WATERS INTO WEDNESDAY
MORNING BEFORE A WAVE DEVELOPS ON IT. IN ANY CASE...THE GRADIENT
FLOW ASSOCIATED WITH THE FRONT AND ASSOCIATED WAVE LOOK FAIRLY WEAK
INTO WEDNESDAY AFTERNOON. AS THE SURFACE DEEPENS NORTHEAST OF THE
AREA LATER WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING...THE GRADIENT
ON THE BACK SIDE COULD GET CLOSE TO BEING ABLE TO SUPPORT SMALL
CRAFT GUSTS...ESPECIALLY ON THE SOUTHERN OCEAN WATERS. THIS LOOKS
FAIRLY TRANSITORY...AS SURFACE HIGH PRESSURE BUILDS IN BEHIND THE
LOW.
HIGH PRESSURE BUILDS BACK OVER THE WATERS FOR THURSDAY AND THURSDAY
EVENING...AGAIN WITH WINDS AND SEAS REMAINING BELOW SMALL CRAFT
LEVELS. SURFACE LOW PRESSURE TRACKING THROUGH THE GREAT LAKES
THURSDAY NIGHT WILL BRING A WARM FRONT TOWARD THE WATERS. THE
GRADIENT AHEAD OF THE FRONT COULD GET CLOSE TO SMALL CRAFT
LEVELS...ESPECIALLY ACROSS THE SOUTHERN WATERS. HOWEVER...AS IT
USUALLY THE CASE DURING WARM AIR ADVECTION SCENARIOS...THE DEPTH OF
THE MIXED LAYER WILL DETERMINE WHETHER THIS CAN OCCUR.
MID RANGE MODELS ARE SHOWING A SURFACE LOW SPINNING UP ON THE FRONT
LATER THURSDAY NIGHT...THEN DEEPENING AS IT MOVES INTO NEW ENGLAND
FRIDAY. THE BEST COLD AIR ADVECTION PROBABLY OCCURS DURING THE
MORNING HOURS...WHICH SHOULD BE COINCIDENT WITH THE BEST PRESSURE
GRADIENT. THE FLOW DOES NOT APPEAR AS THOUGH IT WILL SUPPORT GALE
FORE WINDS...BUT SMALL CRAFT WINDS APPEAR TO BE A GOOD BET FOR
FRIDAY INTO FRIDAY EVENING.
&&
.TIDES/COASTAL FLOODING...
REEDY POINT AND PHILADELPHIA GOT CLOSE TO BLOW OUT TIDES WITH THE
LAST LOW TIDE (WITHIN A COUPLE OF TENTHS). BEING THE WINDS ARE
EXPECTED TO DIMINISH A BIT THIS EVENING AND INTO THE OVERNIGHT
HOURS, TIDES SHOULD RETURN CLOSER TO THE ASTRONOMICAL PREDICTIONS,
BUT THE LOW TIDE OVERNIGHT MAY STILL BE CLOSE TO A FOOT BELOW MLLW.
WE WILL CONTINUE TO MONITOR THE LEVELS IN CASE THEY DO GET LOW AGAIN.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...GALE WARNING UNTIL 1 AM EST MONDAY FOR NJZ025-026.
DE...NONE.
MD...NONE.
MARINE...GALE WARNING UNTIL 1 AM EST MONDAY FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...HAYES
NEAR TERM...GIGI/ROBERTSON
SHORT TERM...ROBERTSON
LONG TERM...HAYES
AVIATION...GIGI/HAYES
MARINE...HAYES/ROBERTSON/GIGI
TIDES/COASTAL FLOODING...HAYES
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
619 PM EST SUN FEB 12 2012
.SYNOPSIS...
HIGH PRESSURE WILL BUILD TOWARD THE REGION TONIGHT...THEN PASS SOUTH
OF THE AREA MONDAY INTO TUESDAY. A WARM FRONT WILL APPROACH THE AREA
TUESDAY EVENING...THEN LOW PRESSURE WILL DEVELOP ON THE FRONT AND
MOVE EAST OF THE AREA WEDNESDAY. HIGH PRESSURE WILL BUILD IN BEHIND
THE FRONT FOR THURSDAY...THEN MOVE OFFSHORE THURSDAY EVENING. ANOTHER
WARM FRONT WILL APPROACH THE REGION LATER THURSDAY EVENING. LOW PRESSURE
WILL DEVELOP ON THE FRONT LATE THURSDAY NIGHT BEFORE ITS MOVES INTO
NEW ENGLAND FRIDAY. A COLD FRONT WILL BRING COLDER WEATHER NEXT
WEEKEND.
&&
.NEAR TERM /THROUGH MONDAY/...
THE ESTF UPDATE WAS BASICALLY TO FOLLOW A COUPLE OF NARROW FLURRY
AND SNOW SHOWER BANDS WORKING ITS WAY INTO NORTHERN NJ. THE HRRR IS
HANDLING THIS PRETTY WELL. 18Z NAM ALSO NOT SHOWING ANY SHEAR
AT 925MB AND 850MB THROUGH 00Z AND THEN START PARTING THEIR WAYS.
REST OF FCST REMAINS PRETTY GOOD.
THE STRONG NORTHWEST FLOW IS EXPECTED TO DIMINISH SOME THIS EVENING
AND INTO THE OVERNIGHT AS THE PRESSURE GRADIENT SLACKENS AS LOW
PRESSURE CONTINUES TO MOVE WELL INTO NORTHERN CANADA. WINDS MAY
REMAIN GUSTY OVERNIGHT, BUT THE STRENGTH IS EXPECTED TO DROP. A VORT
MAX CROSSED OUR AREA THIS AFTERNOON, AND MOSTLY JUST PARTLY TO
MOSTLY CLOUDY SKIES ACCOMPANIED IT; ALTHOUGH, THERE ARE SOME SNOW
SHOWERS/FLURRIES IN THE POCONOS. HOWEVER, THESE SHOULD DIMINISH AS
WELL AS THE VORT MAX MOVES EAST, AND THE NORTHWEST FLOW ALOFT AND AT
THE SURFACE BECOME MORE WESTERLY TOWARD MONDAY MORNING. OTHERWISE,
ANOTHER COOL NIGHT CAN BE EXPECTED, WITH TEMPERATURES EXPECTED TO BE
A FEW DEGREES BELOW NORMAL, BUT NOT QUITE AS COOL AS LAST NIGHT.
&&
.SHORT TERM / MONDAY THROUGH 6 AM MONDAY/...
HIGH PRESSURE IS EXPECTED TO CONTINUE TO BUILD TO OUR SOUTH ON
MONDAY, GIVING US MORE OF A WESTERLY FLOW AT THE SURFACE, WHILE THE
FLOW ALOFT BECOMES MORE WESTERLY AS WELL. THIS SHOULD CUT OFF THE
STRONG LAKE EFFECT FLOW FOR OUR AREA, AND WITH NO SHORT WAVES/VORT
MAXES EXPECTED, WE DO NOT ANTICIPATE ANY PRECIPITATION AT THIS TIME.
THICKNESSES AND 925 MB TEMPERATURES WILL BE ON THE RISE MONDAY, SO
TEMPERATURES WILL BE WARMER THAN TODAY, BUT STILL MAY BE A COUPLE OF
DEGREES BELOW NORMAL.
&&
.LONG TERM /MONDAY THROUGH SUNDAY/...
IT LOOKS LIKE THERE WILL BE TWO SYSTEMS WITH PRECIPITATION CHANCES
DURING THIS PERIOD. THE PERIOD STARTS FAIRLY WARM...BUT COOLS DOWN
FOR THE UPCOMING WEEKEND.
ANY LEFTOVER CUMULUS OR STRATOCUMULUS SHOULD MELT AWAY MONDAY
EVENING. THE GRADIENT SHOULD ALSO BACK OFF...AS HIGH PRESSURE DUCKS
TO THE SOUTH OF THE AREA. WINDS MAY NOT GO CALM...AS THE THERE MAY
BE JUST ENOUGH OF A WESTERLY FLOW TO PREVENT THIS. CLEAR SKIES IN
THE EVENING WILL GIVE WAY OF INCREASING HIGH AND EVENTUALLY MID
LEVEL CLOUDS AHEAD OF A NORTHERN STREAM SHORT WAVE. THE COMBINATION
OF CLOUDS AND WIND SHOULD PREVENT A GOOD RADIATIONAL COOLING
NIGHT...AND LOWS WERE GENERALLY BASED ON A MOS BLEND.
THE WARM AIR ADVECTION AHEAD OF THE SHORT WAVE TUESDAY WILL GO INTO
MOISTENING THE COLUMN...AND THE 1200 UTC GFS APPEARS TO BE TOO
AGGRESSIVE BRINGING PRECIPITATION INTO THE INITIALLY DRY AIR. AS
SUCH...MUCH OF THE DAY SHOULD BE DRY. WINDS WILL START TO BACK AHEAD
OF A SURFACE WARM FRONT SNAKING EAST FROM THE LOWER OHIO VALLEY.
THIS COULD KEEP COASTAL WATERS FROM WARMING...BUT ELSEWHERE HIGHS
WERE GENERALLY BASED ON A MOS BLEND.
WHILE THE MASS FIELDS FOR THE SHORT RANGE MODELS ARE FAIRLY
CLOSE...THE 1200 UTC IS FLATTER AND WEAKER WITH THE SURFACE WAVE
TUESDAY NIGHT. THE WARM AIR ADVECTION IS IMPRESSIVE (WITH A 35 KNOT
LOW LEVEL JET LATE TUESDAY NIGHT?)...BUT IS IT UNCLEAR JUST HOW MUCH
OF THIS WILL GO INTO PRECIPITATION PRODUCTION. FOR NOW...THE BEST
CHANCE OF PRECIPITATION WAS LIMITED TO NORTHERN AREAS...WITH THE
BEST OVERRUNNING POTENTIAL
THE COLUMN IS COLD THROUGH MUCH THE WARM AIR ADVECTION AND
OVERRUNNING...BUT A WARMING BOUNDARY LAYER MAY CAUSE SOME
PRECIPITATION TYPE FORECAST PROBLEMS. AGAIN...IT IS UNCLEAR JUST HOW
IN THE WAY OF PRECIPITATION WILL OCCUR TUESDAY NIGHT...BUT ACROSS THE
HIGHER TERRAIN THIS COULD BE LIGHT SNOW. LOWS WERE GENERALLY BASED
ON THE WARMER NAM MOS NUMBERS.
A SURFACE WAVE LOOKS TO FORM ON THE FRONT WEDNESDAY MORNING...AS THE
MID LEVEL SHORT WAVE PASSES TO THE NORTH. THE BEST DEEPENING SHOULD
OCCUR WELL TO THE NORTHEAST OF THE REGION (AS HAS BEEN THE CASE MOST
OF THE COOL SEASON). THUS...THE BEST CHANCE OF PRECIPITATION WILL BE
IN THE MORNING. THE GRADIENT COULD INCREASE ENOUGH ON THE BACK SIDE
OF THE LOW TO ALLOW WEST TO NORTHWEST WINDS TO BECOME GUSTY IN THE
AFTERNOON...AND THIS COULD ALSO AID IN CLEARING.
AFTER A DRY WEDNESDAY NIGHT AND THURSDAY...THE SECOND PRECIPITATION
EVENT STARTS TO DEVELOP. THE WARM AIR ADVECTION IN THIS EVENT
APPEARS TO BE STRONGER AND BETTER ORGANIZED...AGAIN WITH THE WARM
FRONT AS THE FOCUS. UNLIKE TUESDAY NIGHT...HOWEVER...THE COLUMN WILL
BE IN THE PROCESS OF WARMING...AND THIS SHOULD ULTIMATELY LIMIT
WINTRY PRECIPITATION TO NORTHWEST AREAS AND THE HIGHER TERRAIN. THE
MAIN HOLDOUT IN THIS SCENARIO IS THE 1200 ECMWF...WHICH IS SLOWER
WITH THE MAIN PUNCH OF WARM AIR ADVECTION AND COULD BE SLOWER TO
WARM THE COLUMN.
AT ANY RATE...THE HIGHEST QPF POTENTIAL APPEARS TO FOCUS ON THE WARM
FRONT...WITH LESS THAN ONE-HALF INCH OF QPF FOR AREAS THAT COULD BE
COLD ENOUGH AT THE START FOR WINTRY PRECIPITATION. RIGHT NOW...THIS
DOES NOT LOOKS TO BE A SIGNIFICANT WINTER WEATHER EVENT FOR THE AREA.
THE PRECIPITATION WILL WIND DOWN FRIDAY MORNING AS LOW PRESSURE
DEVELOPS ON THE FRONT...IN RESPONSE TO YET ANOTHER NORTHERN STREAM
MID LEVEL SHORT WAVE.
THE PATTERN LOOKS TO CHANGE TO COLDER WEATHER FOR THE UPCOMING
WEEKEND AS THE LONG WAVE TROUGH POSITION MOVES INTO THE EASTERN
UNITED STATES. HOWEVER...THIS LOOKS TRANSITORY...AS HEIGHTS START TO
RISE IN THE WAKE OF THE EXITING MID LEVEL TROUGH.
&&
.AVIATION /23Z SUNDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
VFR FORECAST WILL BE ISSUED WITH THE LATEST TAFS. WINDS WILL
REMAIN GUSTY INTO THIS EVENING AS FORECAST SOUNDINGS ARE
SUGGESTING 30 PLUS KNOT WIND GUSTS STILL POSSIBLE. THE SUGGESTED
GUSTS HAVE BEEN RUNNING A BIT HOT, SO WE WERE NOT AS ROBUST AS
THEIR SUGGESTIONS. WE KEPT A TRANSITION ZONE OF WEAKER WIND GUSTS
LATER THIS EVENING BEFORE DROPPING THEM OVERNIGHT.
AS FAR AS THE VFR CIGS GO, THE TREND TOWARD LESS IS CONTINUED THIS
EVENING LINGERING IT THE LONGEST AT KABE AND THEN KRDG AND KTTN.
THE DEVELOPING FORECAST INVERSION WE BELIEVE WILL NOT BE STRONG
ENOUGH TO TRAP A VFR CIG BELOW IT AT THE TAF SITES OVERNIGHT.
ON MONDAY VFR CONDITIONS ARE FORECAST TO CONTINUE. THE LATEST
SOUNDING FORECAST CONVECTIVE TEMPERATURES ARE TOO HIGH TO DEVELOP
ANY HOME GROWN CUMULUS OR STRATOCUMULUS. WE CARRIED A BIT OF
CIRRUS ASSOCIATED WITH THE NEXT SYSTEM EXITING THE ROCKIES. WINDS
WILL INCREASE AGAIN ONCE THE SUN RISES AND MIXING STARTS AGAIN.
WHILE IT WILL BE WINDY, PEAK WIND GUSTS SHOULD BE DOWN FROM
TODAY, GENERALLY BETWEEN 20 AND 25 KNOTS. THE GUSTINESS WITH THIS
EVENT SHOULD BE GONE FOR GOOD ONCE THE SUN SETS AS PER THE 30HR
KPHL TAF.
OUTLOOK...
MONDAY NIGHT LOOKS VFR. HIGH AND EVENTUALLY MID LEVEL CLOUDINESS
WILL INCREASE MONDAY NIGHT AND CONTINUE INTO TUESDAY MORNING.
VFR CONDITIONS ARE EXPECTED TUESDAY AS A WARM FRONT APPROACHES. IT
IS NOT CLEAR JUST HOW MUCH PRECIPITATION WILL OCCUR WITH THE
FRONT...AND FOR NOW IT APPEARS AS THOUGH CONDITIONS MAY DROP TO MVFR
TUESDAY NIGHT AS THE FRONT BISECTS THE AREA. IF PRECIPITATION DOES
DEVELOP...LOCAL IFR CONDITIONS ARE POSSIBLE...BUT THIS LOOKS LIKE A
LONG SHOT.
CONDITIONS WILL IMPROVE WEDNESDAY AS LOW PRESSURE DEVELOPS ON THE
FRONT AND MOVES NORTHEAST. HIGH PRESSURE WILL BRING VFR CONDITIONS
LATE WEDNESDAY INTO THURSDAY AFTERNOON. WINDS COULD GUST TO 25 KNOTS
FROM THE WEST NORTHWEST AT TIMES WEDNESDAY EVENING...BUT THIS LOOKS
LIKE A 3 TO 6 HOUR POSSIBILITY AT MOST.
ANOTHER WARM FRONT WILL APPROACH THURSDAY. CONDITIONS COULD DROP TO
MVFR AHEAD OF THE FRONT...AS WINDS ASSUME PRE WARM FRONTAL
DIRECTIONS. MOST MID RANGE MODELS SUGGEST THERE IS A BETTER CHANCE
OF PRECIPITATION WITH THIS WARM FRONT...AND MVFR CONDITIONS ARE
EXPECTED. THERE IS A CHANCE FOR IFR CONDITIONS...ESPECIALLY IF LOW
PRESSURE FORMS ON THE FRONT LATER THURSDAY NIGHT...AND THIS COULD
CONTINUE INTO FRIDAY MORNING.
AS THE LOW PULLS AWAY FRIDAY MORNING...VFR CONDITIONS ARE EXPECTED
TO RETURN. WEST TO NORTHWEST WINDS COULD GUST TO 25 TO 30 KNOTS AT
TIMES FRIDAY AS THE GRADIENT TIGHTENS DURING THE MORNING.
&&
.MARINE...
WE HAVE DECIDED TO LEAVE THE GALE WARNING UP AT LEAST INTO THE
EVENING HOURS SINCE WINDS ARE STILL GUSTING IN THE LOW 30S ACROSS
THE LAND AND AT A FEW BUOYS. THE GALE WARNING MAY BE ABLE TO BE
CANCELLED BEFORE THE CURRENT EXPIRATION, AT WHICH TIME A SMALL CRAFT
ADVISORY WILL LIKELY NEED TO REPLACE IT. ONCE A SMALL CRAFT ADVISORY
IS ISSUED, IT WILL LIKELY CONTINUE INTO THE DAY ON MONDAY AS WINDS
ARE STILL EXPECTED TO GUST AROUND 25-30 KNOTS, ALTHOUGH WINDS ARE
EXPECTED TO DIMINISH LATE IN THE DAY MONDAY.
THE GRADIENT FLOW WILL BE SLACKENING MONDAY EVENING...AS THE SURFACE
HIGH BUILDS TOWARD THE REGION. WINDS COULD BE CLOSE TO SMALL CRAFT
VALUES IN GUSTS MONDAY EVENING.. EVEN THIS BACKS OFF LATER MONDAY
NIGHT AND SUB SMALL CRAFT CONDITIONS ARE EXPECTED INTO TUESDAY
EVENING.
A WARM FRONT WILL APPROACH THE WATERS TUESDAY NIGHT. IT IS NOT CLEAR
WHETHER THE FRONT ACTUALLY GETS NORTH OF THE WATERS INTO WEDNESDAY
MORNING BEFORE A WAVE DEVELOPS ON IT. IN ANY CASE...THE GRADIENT
FLOW ASSOCIATED WITH THE FRONT AND ASSOCIATED WAVE LOOK FAIRLY WEAK
INTO WEDNESDAY AFTERNOON. AS THE SURFACE DEEPENS NORTHEAST OF THE
AREA LATER WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING...THE GRADIENT
ON THE BACK SIDE COULD GET CLOSE TO BEING ABLE TO SUPPORT SMALL
CRAFT GUSTS...ESPECIALLY ON THE SOUTHERN OCEAN WATERS. THIS LOOKS
FAIRLY TRANSITORY...AS SURFACE HIGH PRESSURE BUILDS IN BEHIND THE
LOW.
HIGH PRESSURE BUILDS BACK OVER THE WATERS FOR THURSDAY AND THURSDAY
EVENING...AGAIN WITH WINDS AND SEAS REMAINING BELOW SMALL CRAFT
LEVELS. SURFACE LOW PRESSURE TRACKING THROUGH THE GREAT LAKES
THURSDAY NIGHT WILL BRING A WARM FRONT TOWARD THE WATERS. THE
GRADIENT AHEAD OF THE FRONT COULD GET CLOSE TO SMALL CRAFT
LEVELS...ESPECIALLY ACROSS THE SOUTHERN WATERS. HOWEVER...AS IT
USUALLY THE CASE DURING WARM AIR ADVECTION SCENARIOS...THE DEPTH OF
THE MIXED LAYER WILL DETERMINE WHETHER THIS CAN OCCUR.
MID RANGE MODELS ARE SHOWING A SURFACE LOW SPINNING UP ON THE FRONT
LATER THURSDAY NIGHT...THEN DEEPENING AS IT MOVES INTO NEW ENGLAND
FRIDAY. THE BEST COLD AIR ADVECTION PROBABLY OCCURS DURING THE
MORNING HOURS...WHICH SHOULD BE COINCIDENT WITH THE BEST PRESSURE
GRADIENT. THE FLOW DOES NOT APPEAR AS THOUGH IT WILL SUPPORT GALE
FORE WINDS...BUT SMALL CRAFT WINDS APPEAR TO BE A GOOD BET FOR
FRIDAY INTO FRIDAY EVENING.
&&
.TIDES/COASTAL FLOODING...
REEDY POINT AND PHILADELPHIA GOT CLOSE TO BLOW OUT TIDES WITH THE
LAST LOW TIDE (WITHIN A COUPLE OF TENTHS). BEING THE WINDS ARE
EXPECTED TO DIMINISH A BIT THIS EVENING AND INTO THE OVERNIGHT
HOURS, TIDES SHOULD RETURN CLOSER TO THE ASTRONOMICAL PREDICTIONS,
BUT THE LOW TIDE OVERNIGHT MAY STILL BE CLOSE TO A FOOT BELOW MLLW.
WE WILL CONTINUE TO MONITOR THE LEVELS IN CASE THEY DO GET LOW AGAIN.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...GALE WARNING UNTIL 1 AM EST MONDAY FOR NJZ025-026.
DE...NONE.
MD...NONE.
MARINE...GALE WARNING UNTIL 1 AM EST MONDAY FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...HAYES
NEAR TERM...GIGI/ROBERTSON
SHORT TERM...ROBERTSON
LONG TERM...HAYES
AVIATION...GIGI/HAYES
MARINE...HAYES/ROBERTSON
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
346 PM EST SAT FEB 11 2012
.SYNOPSIS...
LOW PRESSURE EXITING TO THE CANADIAN MARITIMES AND HIGH PRESSURE TO
OUR WEST OVER THE PLAINS STATES WILL PRODUCE A STRONG NORTHWESTERLY
FLOW WITH COLDER AIR MOVING INTO OUR REGION. LATE SUNDAY, A FRONTAL
BOUNDARY WILL PASS THROUGH THE AREA. HIGH PRESSURE BUILDS INTO THE
MID ATLANTIC ON MONDAY, FOLLOWED BY A COUPLE OF WEAK SYSTEMS
AFFECTING THE REGION DURING THE MIDDLE TO END OF THE UPCOMING WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
TWO FORECAST ISSUES FOR TONIGHT INCLUDE SNOW SHOWERS/SQUALLS WITH
THE ARCTIC FRONT...AND WIND GUSTS IN THE COLD AIR ADVECTION BEHIND
THE FRONT. A WIND ADVISORY WILL BE ISSUED FOR SOUTHERN PORTIONS OF
THE AREA WITH THE NEW FORECAST.
CURRENTLY...THE ARCTIC FRONT STRETCHES ACROSS CENTRAL PENNSYLVANIA
AND CENTRAL MARYLAND. SNOW SHOWERS WITH THE FRONT ARE FAIRLY
IMPRESSIVE (AND ALMOST LOOKS LIKE A SUMMER LIKE SQUALL LINE). THE
SNOW SHOWERS ARE BEING SUPPORTED BY A FAIRLY POTENT MID LEVEL SHORT
WAVE LOCATED ACROSS WESTERN PENNSYLVANIA...WHERE MID LEVEL LAPSE
RATES ARE STEEPENING QUICKLY. AHEAD OF THE FRONT...SCATTERED SNOW
SHOWERS NORTH AND RAIN SHOWERS SOUTH HAVE DEVELOPED IN THE BROAD ARE
OF LIFT AHEAD OF THE SHORT WAVE.
EXTRAPOLATION AND THE LATEST HRRR MODEL RUN (WHICH HAS HAD A GOOD
HANDLE ON THE FRONTAL POSITION AND STRENGTH ALL DAY) PLACES THE
FRONT IN THE DELAWARE VALLEY CLOSE TO 2300 UTC. SINCE THERE IS SNOW
SHOWER COVERAGE SHOULD MORE OR LESS MAINTAIN ITSELF...THE BEST
CHANCE OF SNOW SHOWERS SHOULD OCCUR ACROSS THE SOUTHERN HALF OF THE
AREA...WHERE THE MOISTURE WITH THE FRONT IS DEEPEST.
SOME LOCATIONS COULD SEE AN INCH OF SNOW WITH THIS FEATURE. SINCE
SURFACE TEMPERATURES ARE ABOVE FREEZING IN MOST PLACES (AND SHOULD
REMAIN THERE THROUGH THE FRONTAL PASSAGE)...WE HAVE DECIDED NOT TO
GO WITH AN WINTER WEATHER ADVISORY FOR THE SNOW SHOWERS. HOWEVER...
THE SNOW SHOWERS COULD HAVE GUSTY WINDS AS WELL...AND THREAT SHOULD
BEST BE HANDLED BY A SPECIAL WEATHER STATEMENT.
THE ARCTIC FRONT WILL CLEAR THE COAST AFTER ABOUT 1000 PM...WITH THE
BEST CHANCE OF SNOW SHOWERS FOLLOWING CLOSELY BEHIND. AFTER
THIS...IMPRESSIVE COLD AIR ADVECTION AND A TIGHTENING GRADIENT RAISE
THE SPECTER FOR STRONG WINDS OVERNIGHT...MAINLY ACROSS SOUTHERN
AREAS.
THE PRESSURE GRADIENT LOOKS TO FALL OUT ACROSS THE SOUTHERN HALF OF
THE FORECAST AREA...WITH THE TIGHTEST GRADIENT BETWEEN 0600 AND 1200
UTC SUNDAY. DURING THE BEST COLD AIR ADVECTION...MODEL SOUNDINGS
FROM BOTH THE 1200 UTC NAM AND GFS SHOW 45 KNOT WINDS AT THE TOP OF
THE INVERSION NEAR 2100 FEET...PEAKING BETWEEN 0600 UTC AND 0900
UTC. THIS IS PROBABLY BORDERLINE FOR WIND ADVISORY CRITERIA...BUT 3
HOUR PRESSURE RISES NEAR 5 MB MAY BE ENOUGH TO ALLOW SOME OF THAT
MOMENTUM TO REACH THE SURFACE.
THE WIND ADVISORY COVERS NORTHEAST MARYLAND...DELAWARE...A PART OF
SOUTHEAST PENNSYLVANIA (INCLUDING PHILADELPHIA)...AND THE SOUTHERN
HALF OF NEW JERSEY. WHILE THE STRONGEST WINDS MAY BE JUST SOUTH OF
AN KMQS-KPHL-KMJX...THE NORTHERN EDGE OF THE WIND ADVISORY WILL
INCLUDE THE METRO AREA.
LOWS TONIGHT SHOULD OCCUR TOWARD DAYBREAK IN THE BEST COLD AIR
ADVECTION. GIVEN WHAT IS OCCURRING TO THE WEST NOW...LOWS WERE BASED
ON THE COLDER GFS MOS NUMBERS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
COLD AIR ADVECTION WILL BE IN PROGRESS SUNDAY MORNING...AS THE
STRONGEST LOW TO MID LEVEL WINDS MOVE JUST OFFSHORE. THE PRESSURE
GRADIENT IS AT ITS TIGHTEST IN THE MORNING...AND AT THIS POINT DOES
NOT APPEAR TO SUPPORT WIND ADVISORY LEVELS GUSTS. MODEL SOUNDINGS
ALSO SUGGEST THAT THE GUST POTENTIAL REMAINS BELOW WIND ADVISORY
LEVELS AS WELL.
A SECONDARY COLD FRONT WILL CROSS THE REGION IN THE AFTERNOON...
SUPPORTED BY A FAIRLY VIGOROUS MID LEVEL SHORT WAVE. THE COLD AIR
ADVECTION BEHIND THESE FEATURES COULD RESULT IN WIND GUSTS GETTING
CLOSE TO WIND ADVISORY LEVELS DURING THE MID TO LATE AFTERNOON
(WHICH IS SUPPORTED BY MODEL SOUNDINGS AROUND 2100 UTC). WHILE THERE
IS SOME POTENTIAL FOR GUSTS TO REACH 45 MPH SUNDAY AFTERNOON...WILL
HOLD OFF ON DOING THAT JUST YET.
SOME CLEARING IS POSSIBLE IN THE MORNING AS THE COLD AIR ADVECTION
MAXIMIZES AND DRY AIR SETTLES IN BEHIND THE ARCTIC FRONT. THIS MAY
END UP BEING SHORT LIVED HOWEVER...AS THE CONVECTIVE TEMPERATURES
PLUMMET IN THE NEW AIRMASS. MODEL SOUNDINGS SUGGEST THAT CUMULUS
WILL DEVELOP DURING THE MID MORNING HOURS...AND WILL SPREAD OUT
UNDER THE INVERSION DURING THE AFTERNOON. IN ADDITION...MID LEVEL
CLOUDINESS WITH THE ABOVEMENTIONED SHORT WAVE PROBABLY COVERS MOST
OF THE NORTHERN TWO THIRDS OF THE AREA IN THE AFTERNOON. SO...MOST
PLACES SHOULD SEE SOME SUNSHINE FADE BEHIND CLOUDINESS (WHILE THE
TERRAIN MAY SEE LITTLE IF ANY SUN DURING THE DAY SUNDAY.
THE SHORT WAVE WILL ALSO INCREASE THE UPSLOPE FLOW ACROSS THE HIGHER
TERRAIN...AND THIS COULD RESULT IN SCATTERED SNOW SHOWERS IN THE
MOUNTAINS DURING THE MORNING. THE REINFORCING COLD FRONT IN THE
AFTERNOON MAY ENHANCE THIS...BUT FOR NOW THE SNOW SHOWER CHANCES
WERE CAPPED. IN ADDITION...FLURRIES WITH THE SHORT WAVE WERE CARRIED
ACROSS THE UPPER DELAWARE VALLEY...AS WELL AS MUCH OF NORTHERN NEW
JERSEY.
850 MB TEMPERATURES STABILIZING NEAR MINUS 14 CELSIUS SUGGEST THAT
HIGHS IN MOST PLACES OUTSIDE THE TERRAIN SHOULD TOP OUT NEAR THE
FREEZING MARK. THIS IS CLOSER TO THE COLDER NAM MOS NUMBERS...WHICH
WERE USED FOR HIGHS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
TO BEGIN THE LONG TERM, A STRONG MID LEVEL TROUGH AND A WEAK FRONT
WILL BE EXITING OFF TO OUR EAST. OTHER THAN SOME LEFTOVER FLURRIES
IN THE NORTHWEST FLOW OVER THE HIGHER TERRAIN OF THE POCONOS, A DRY
FORECAST HAS BEEN MAINTAINED FOR SUNDAY NIGHT AS THE ABOVE FEATURES
MOVE EAST AND HIGH PRESSURE TO OUR SOUTHWEST GRADUALLY BEGINS TO
BUILD INTO THE REGION. HIGH PRESSURE NEARBY WILL YIELD FAIR WEATHER
ACROSS THE REGION ON MONDAY WITH AMPLE SUN AND TEMPERATURES A FEW
DEGREES MILDER THAN OVER THE WEEKEND. FOR THE TUESDAY TO WEDNESDAY
TIMEFRAME, THE ECMWF AND GFS CONTINUE TO SHOW A FAIRLY DISORGANIZED
MID LEVEL DISTURBANCE PASSING THROUGH THE MID ATLANTIC REGION. WITH
DIFFERENCES BETWEEN THE MODELS ON THE HANDLING OF THIS SYSTEM, FEW
CHANGES WERE MADE IN THIS TIMEFRAME WITH SLIGHT CHANCE POPS FOR
RAIN/SNOW SHOWERS MAINTAINED. OF NOTE WILL BE THE MODERATING TREND
IN TEMPERATURES AS MORE OF A SOUTHWESTERLY FLOW WILL BE IN PLACE
DURING THIS TIMEFRAME. FOR THE END OF THE WEEK, A STRONGER SYSTEM
MAY POTENTIALLY AFFECT THE REGION. FOR NOW, THE MODELS HAVE LOW
PRESSURE APPROACHING FROM THE OHIO VALLEY REGION ON THURSDAY, WITH
THIS SYSTEM REACHING OUR AREA THURSDAY NIGHT INTO FRIDAY. HOWEVER,
THERE IS QUITE A BIT OF DIFFERENCE BETWEEN THE MODELS WITH THE TRACK
AND STRENGTH OF LOW PRESSURE. FOR NOW, CHANCE AND SLIGHT CHANCE POPS
WERE KEPT FROM THURSDAY NIGHT INTO FRIDAY WITH THE PASSAGE OF THIS
SYSTEM. WHAT DOES LOOK TO CONTINUE THROUGH THE END OF THE WEEK ARE
THE MODERATING TEMPERATURES, WITH HIGH TEMPERATURES RANGING FROM THE
MID 40S NORTH TO THE LOW 50S SOUTH ON FRIDAY. FOR THE MOST PART, A
BLEND OF MOS AND HPC GUIDANCE ALONG WITH CONTINUITY WAS USED FOR
TEMPERATURES THROUGH THE LONG TERM PERIOD.
&&
.AVIATION /21Z SATURDAY THROUGH THURSDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
VARYING CONDITIONS EARLY THIS AFTERNOON WERE SLOWING IMPROVING AS
THE PRECIPITATION ENDS FROM WEST TO EAST. HOWEVER...MOISTURE REMAINS
TRAPPED UNDER THE INVERSION. A RECENT AMDAR SOUNDING FROM KPHL
SUGGESTS THAT THE INVERSION MAY BE READY TO BREAK...AND MVFR
CONDITIONS SHOULD BE THE RULE THROUGH 2200 UTC.
AN ARCTIC FRONT WILL CROSS THE REGION THIS EVENING...CENTERED AROUND
0000 UTC. FOR THE MOST PART...MVFR CONDITIONS HAVE BEEN ACCOMPANYING
THE FRONTAL PASSAGE ACROSS WESTERN AND CENTRAL PENNSYLVANIA.
THUS...MVFR CONDITIONS ARE FORECAST BETWEEN 0000 UTC AND 0400
UTC...WITH THE LOWEST CONDITIONS FROM KPHL SOUTH.
AFTER THE FRONT PASSES AND THE INVERSION ASSOCIATED WITH THE FRONT
INCREASES...VFR CONDITIONS SHOULD RETURN AFTER 0600 UTC SUNDAY.
HOWEVER...THE GRADIENT BEHIND THE ARCTIC FRONT TIGHTENS FAIRLY
QUICKLY...AND SHOULD EASILY SUPPORT SUSTAINED WINDS BETWEEN 17 AND
22 KNOTS ACROSS THE BOARD. MODEL SOUNDINGS SUGGEST THAT WINDS WILL
RANGE BETWEEN 35 AND 41 KNOTS AT THE TOP OF THE INVERSION DURING THE
BEST OF THE COLD AIR ADVECTION...SO GUSTS TO 35 KNOTS ARE EXPECTED
DURING THE OVERNIGHT HOURS...WITH THE STRONGEST GUSTS FROM KPHL
SOUTH.
VFR CEILINGS COULD BREAK FOR A TIME LATER TONIGHT AND SUNDAY
MORNING. THE NEW AIRMASS HAS FAIRLY LOW CONVECTIVE TEMPERATURES
ASSOCIATED WITH IT...SO SUNSHINE WILL BE SELF DESTRUCTIVE...ALLOWING
CUMULUS/STRATOCUMULUS TO DEVELOP. THE GRADIENT CONTINUES TO SUPPORT
SUSTAINED WINDS BETWEEN 18 AND 25 KNOTS FOR THE REMAINDER OF THE
DAY...AFTER A BRIEF LULL NEAR SUNRISE. MODEL SOUNDINGS SUGGEST THAT
THE GUST POTENTIAL IS NOT QUITE AS HIGH AS TONIGHT...AS THE MOMENTUM
TRANSFER IS NOT AS EFFICIENT AS TONIGHT.
OUTLOOK...
WITH HIGH PRESSURE GRADUALLY BUILDING INTO THE REGION FROM SUNDAY
NIGHT THROUGH MONDAY, VFR CONDITIONS ARE EXPECTED. IN THE LATE
TUESDAY TO WEDNESDAY TIMEFRAME, A WEAK SYSTEM MAY BRING
PRECIPITATION AND SOME LOWERING IN CEILINGS OR VISIBILITIES TO THE
AREA.
&&
.MARINE...
THE GRADIENT IS STARTING TO INCREASE AS THE SURFACE LOW DEEPENS WELL
TO THE EAST OF THE NORTH CAROLINA COAST. WINDS AND SEAS ARE ON THE
THRESHOLD OF SMALL CRAFT LIMITS...ESPECIALLY ACROSS THE SOUTHERN
WATERS.
AN ARCTIC COLD FRONT WILL CROSS THE WATERS THIS EVENING...REACHING
THE DELAWARE BAY BEFORE 0100 UTC...AND REACHING THE COASTAL WATERS
AFTER 0400 UTC SUNDAY. THE GRADIENT BEHIND THE FRONT IN THE COLD AIR
ADVECTION IS IMPRESSIVE OVER LAND TO THE WEST...WHERE GUSTS TO 35
KNOTS HAVE BEEN COMMON. THE GALE FORCE GUSTS ARE EXPECTED TO
COMMENCE SHORTLY AFTER THE PASSAGE OF THE ARCTIC FRONT. THE PRESSURE
GRADIENT REACHES IT MAXIMUM BETWEEN 0600 UTC AND 1200 UTC SUNDAY.
DURING THIS TIME...THE GRADIENT LOOKS TO SUPPORT GALE FORCE WINDS
ACROSS ALL WATERS...WITH THE HIGHEST GUST POTENTIAL ACROSS THE
SOUTHERN OCEAN WATERS AND LOWER DELAWARE BAY.
THE GRADIENT MAINTAINS AN INTENSITY SLIGHTLY LOWER THAN LATE TONIGHT
FOR MOST OF SUNDAY. THE HIGHEST WINDS GUSTS PROBABLY OCCUR IN THE
MORNING ACROSS THE SOUTHERN WATERS. IN FACT...WINDS COULD DROP BELOW
GALE FORCE FOR A TIME LATE IN THE MORNING AND EARLY AFTERNOON.
ANOTHER COLD FRONT DROPPING ACROSS THE WATERS IN THE AFTERNOON COULD
BRING WINDS BACK TO GALE FORCE...AS ANOTHER SHORT OF COLD AIR
CROSSES THE WATERS. MODEL SOUNDINGS SUGGEST THAT GUSTS BETWEEN 35
AND 40 KNOTS ARE POSSIBLE ACROSS THE NORTHERN OCEAN WATERS...WITH
SLIGHTLY LESS POTENTIAL ACROSS THE SOUTHERN WATERS.
GALE CONDITIONS ARE ANTICIPATED TO LINGER INTO SUNDAY NIGHT, WITH
DECREASING WINDS AND DIMINISHING SEAS GOING INTO EARLY MONDAY. IN
FACT, FROM MONDAY THROUGH MID-WEEK, WINDS AND SEAS ARE EXPECTED TO
BE BELOW ADVISORY CRITERIA, WITH HIGH PRESSURE OVER THE REGION ON
MONDAY AND A WEAK SYSTEM MOVING THROUGH THE AREA FOR MID-WEEK.
&&
.TIDES/COASTAL FLOODING...
AS THE STRONG NORTHWEST FLOW DEVELOPS...ANY POSITIVE TIDE DEPARTURES
ON THE OCEAN AND ACROSS THE BAYS SHOULD DISAPPEAR. NONE OF THE TIDAL
GUIDANCE SUGGESTS THAT BLOWOUT TIDES WILL BE AN ISSUE TONIGHT AND
SUNDAY.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WIND ADVISORY FROM 7 PM THIS EVENING TO 5 AM EST SUNDAY FOR
PAZ067-070-071.
NJ...WIND ADVISORY FROM 7 PM THIS EVENING TO 5 AM EST SUNDAY FOR
NJZ016>024-026-027.
DE...WIND ADVISORY FROM 7 PM THIS EVENING TO 5 AM EST SUNDAY FOR
DEZ001>004.
MD...WIND ADVISORY FROM 7 PM THIS EVENING TO 5 AM EST SUNDAY FOR
MDZ008-012-015-019-020.
MARINE...GALE WARNING UNTIL 1 AM EST MONDAY FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...KLINE
NEAR TERM...HAYES
SHORT TERM...HAYES
LONG TERM...KLINE
AVIATION...HAYES/KLINE
MARINE...HAYES/KLINE
TIDES/COASTAL FLOODING...HAYES
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
1239 PM EST SAT FEB 11 2012
.SYNOPSIS...
LOW PRESSURE SOUTHEAST OF THE AREA WILL DEEPEN AS IT MOVE
NORTHEAST THIS AFTERNOON. A COLD FRONT WILL CROSS OUR AREA THIS
LATE AFTERNOON AND THIS EVENING. THERE WILL BE A STRONG NORTHWEST FLOW
AND SOME COLDER AIR IN THE WAKE OF THE FRONT. A SECONDARY COLD
FRONT WILL CROSS THE AREA LATE SUNDAY. HIGH PRESSURE WILL BUILD IN
ON MONDAY, THEN TWO WEAK SYSTEMS COULD AFFECT THE REGION DURING
THE MIDDLE TO LATTER PART OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE BANDED FEATURES HAVE MOVED OFFSHORE WITH THE LAST OF THE MID
LEVEL FRONTOGENETIC FORCING. PATCHES OF LIGHT SNOW CONTINUE TO
FORM IN THE MOIST COLUMN LEFT IN PLACE ACROSS EASTERN PENNSYLVANIA
AND MARYLAND EARLY THIS AFTERNOON.
ANOTHER BATCH OF SNOW SHOWERS IS MOVING STEADILY ACROSS EAST
CENTRAL MARYLAND...AND SHOULD IMPACT THE NORTHEAST MARYLAND ZONES
LATER THIS AFTERNOON. THE LATEST HRRR SHOWS AN ALMOST SQUALL- LIKE
STRUCTURE MOVING THROUGH THE PENNSYLVANIA AND EASTERN MARYLAND BY
ABOUT 2200 UTC. GIVEN THE LAPSE RATES IN THE LOW AND MID
LEVELS...THIS TYPE OF STRUCTURE LOOKS POSSIBLE. A BURST OF SNOW IS
POSSIBLE WITH THE FRONT ITSELF.
FOR NOW...THE POTENTIAL FOR SNOW SHOWERS WAS INCREASED ACROSS
SOUTHERN AREAS. IF THE CONVECTIVE ELEMENTS PERSIST...A SPECIAL
WEATHER STATEMENT WILL BE ISSUED TO HIGHLIGHT THE POTENTIAL FOR A
BRIEF PERIOD OF MODERATE SNOW THERE. ELSEWHERE...NOT MUCH CHANGE
TO THE ONGOING FORECAST...AS TEMPERATURES PROBABLY DO NOT MOVE
MUCH FROM WHERE THEY ARE NOW.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
THE UPPER TROUGH WILL CROSS THE REGION TONIGHT. A SHARP SFC COLD
FRONT WILL CROSS THE AREA THIS EVENING. IT WILL BE ACCOMPANIED BY
GUSTY WINDS...FALLING TEMPERATURES AND SCATTERED SNOW SHOWERS. A
BETTER CHC FOR THE SNOW SHOWERS WILL BE ACROSS THE DELMARVA CLOSER
TO THE VORT MAX ALONG THE H5 TROUGH. HIGH CHC OR LOW LIKELY POPS
WILL BE OVER THE DELMARVA (AND CHESTER CTY PA) WHILE LOWER CHC POPS
WILL BE OVER THE REST OF PA AND NJ. TEMPERATURES WILL PLUNGE INTO
THE TEENS OVER THE POCONOS...LEHIGH VALLEY AND NRN NJ AND INTO THE
20S ELSEWHERE. WIND CHILL VALUES WILL BE IN THE SINGLE DIGITS WITH
SOME SUB-ZERO READINGS OVER THE SRN POCONOS. WINDS WILL GUST IN THE
25 TO 35 KT RANGE TONIGHT...ESPECIALLY OVER THE SRN COUNTIES.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
THE FAIRLY SHARP MID LEVEL TROUGH AXIS WILL DEVELOP A NEGATIVE
TILT AS IT LIFTS AWAY FROM OUR AREA ON SUNDAY, AND A SECONDARY
IMPULSE WILL DROP DOWN THE BACK SIDE OF IT AROUND SUNDAY EVENING.
SURFACE PRESSURE RISES IN THE WAKE OF THE TROUGH ARE ROBUST ENOUGH
TO FORECAST LAND WIND GUSTS IN EXCESS OF 30 MPH, BUT MODEL
SOUNDINGS AREN`T PRESENTLY SHOWING A WIND ADVISORY LEVEL FLOW. THE
SECONDARY IMPULSE ALSO CARRIES SOME LESSER PRESSURE RISES IN ITS
WAKE. THE SOUNDINGS ACROSS THE NORTH ARE CAPPED AT ABOUT 7000 FT
AND WE CARRY A CYCLONIC SURFACE FLOW SUNDAY INTO SUNDAY NIGHT, SO
WE CONTINUE TO CARRY FLURRIES NORTH DURING THIS TIME FRAME.
THE MODELS THEN AGREE TO TAKE A MID LEVEL IMPULSE ACROSS THE AREA IN
THE TUESDAY TO WEDNESDAY TIME FRAME, AND THEN START TO DIVERGE ON
THE HANDLING OF ANOTHER AND POSSIBLY MORE ROBUST SYSTEM TOWARD THE
END OF THE WORK WEEK. WE MADE MODEST CHANGES WITH RESPECT TO THE
FORMER AND FOLLOWED CONTINUITY WITH RESPECT TO THE LATTER.
TEMPERATURES WILL START OFF BELOW NORMAL EARLY THIS PERIOD,
TRANSITION TO NORMAL EARLY IN THE WORK WEEK AND THEN GO ABOVE
NORMAL FOR THE LATTER PART OF THE PERIOD.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
VARYING CONDITIONS EARLY THIS AFTERNOON WERE SLOWING IMPROVING AS
THE PRECIPITATION ENDS FROM WEST TO EAST. HOWEVER...MOISTURE REMAINS
TRAPPED UNDER THE INVERSION. A RECENT AMDAR SOUNDING FROM KPHL
SUGGESTS THAT THE INVERSION MAY BE READY TO BREAK...AND MVFR
CONDITIONS SHOULD BE THE RULE THROUGH 2200 UTC.
AN ARCTIC FRONT WILL CROSS THE REGION THIS EVENING...CENTERED AROUND
0000 UTC. FOR THE MOST PART...MVFR CONDITIONS HAVE BEEN ACCOMPANYING
THE FRONTAL PASSAGE ACROSS WESTERN AND CENTRAL PENNSYLVANIA.
THUS...MVFR CONDITIONS ARE FORECAST BETWEEN 0000 UTC AND 0400
UTC...WITH THE LOWEST CONDITIONS FROM KPHL SOUTH.
AFTER THE FRONT PASSES AND THE INVERSION ASSOCIATED WITH THE FRONT
INCREASES...VFR CONDITIONS SHOULD RETURN AFTER 0600 UTC SUNDAY.
HOWEVER...THE GRADIENT BEHIND THE ARCTIC FRONT TIGHTENS FAIRLY
QUICKLY...AND SHOULD EASILY SUPPORT SUSTAINED WINDS BETWEEN 17 AND
22 KNOTS ACROSS THE BOARD. MODEL SOUNDINGS SUGGEST THAT WINDS WILL
RANGE BETWEEN 35 AND 41 KNOTS AT THE TOP OF THE INVERSION DURING THE
BEST OF THE COLD AIR ADVECTION...SO GUSTS TO 35 KNOTS ARE EXPECTED
DURING THE OVERNIGHT HOURS...WITH THE STRONGEST GUSTS FROM KPHL
SOUTH.
VFR CEILINGS COULD BREAK FOR A TIME LATER TONIGHT AND SUNDAY
MORNING. THE NEW AIRMASS HAS FAIRLY LOW CONVECTIVE TEMPERATURES
ASSOCIATED WITH IT...SO SUNSHINE WILL BE SELF DESTRUCTIVE...ALLOWING
CUMULUS/STRATOCUMULUS TO DEVELOP. THE GRADIENT CONTINUES TO SUPPORT
SUSTAINED WINDS BETWEEN 18 AND 25 KNOTS FOR THE REMAINDER OF THE
DAY...AFTER A BRIEF LULL NEAR SUNRISE. MODEL SOUNDINGS SUGGEST THAT
THE GUST POTENTIAL IS NOT QUITE AS HIGH AS TONIGHT...AS THE MOMENTUM
TRANSFER IS NOT AS EFFICIENT AS TONIGHT.
OUTLOOK...
OUTSIDE OF ANY SNOW SHOWER ACTIVITY THAT MAY OCCUR ON SUNDAY INTO
SUNDAY EVENING (ESPECIALLY NORTHWEST), WE EXPECT VFR CONDITIONS INTO
TUESDAY. THE WEAK WEATHER SYSTEM DURING THE MIDWEEK PERIOD MAY CAUSE
SOME DETERIORATION IN CONDITIONS.
&&
.MARINE...
WE WILL CONVERT THE GALE WATCH TO A WARNING AND EXTEND IT OUT UNTIL
06Z MONDAY.
LOW PRESSURE WILL DEEPEN OFF THE EAST COAST AND TRACK WELL TO OUR
EAST TODAY THROUGH SUNDAY. THE GRADIENT OVER THE WATERS WILL NOT BE
VERY STRONG TODAY...BUT WILL STRENGTHEN SIGNIFICANTLY LATER TODAY
AND REMAIN STRONG INTO EARLY NEXT WEEK. A COLD FRONT WILL CROSS THE
WATERS THIS EVENING AND THE STRONG WIND GUSTS WILL FOLLOW IT. GUSTS
TO 40 KTS ARE POSSIBLE. SCATTERED SNOW SHOWERS WITH LOWER VSBYS MAY
ACCOMPANY THE FRONT. GUSTY WINDS AND ENHANCED SEAS WILL CONTINUE
THROUGH TONIGHT.
GALES ARE EXPECTED TO LAST INTO SUNDAY, AND THEY MAY LINGER INTO
SUNDAY EVENING WITH A SECONDARY FRONT CROSSING THE AREA. AFTER
THAT, CONDITIONS SHOULD DROP TO SUB-ADVISORY AND REMAIN SO THROUGH
THE MIDDLE OF THE WEEK.
&&
.TIDES/COASTAL FLOODING...
NONE OF THE LATEST OFS PROGS ARE TAKING ANY OF THE REFERENCE GAUGES
TO WITHIN A HALF FOOT OF THE MINOR TIDAL FLOODING BENCHMARKS. NO
DEPARTURES THIS MORNING WERE MUCH IN EXCESS OF 0.5 FT. WE WILL
CONTINUE TO MONITOR TIDES IN THE EVENT THAT THE PROGS ARE UNDERDONE,
BUT ANY THREAT OF MINOR TIDAL FLOODING WILL DIMINISH ONCE WINDS COME
AROUND TO NORTHWEST. WE THEN WILL TURN OUR CONCERN TO THE POSSIBILITY
OF BLOWOUT TIDES, WHICH ALSO IS DOWNPLAYED BY OFS PROGS.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...GALE WARNING FROM 6 PM THIS EVENING TO 1 AM EST MONDAY FOR
NJZ025-026.
DE...NONE.
MD...NONE.
MARINE...GALE WARNING FROM 6 PM THIS EVENING TO 1 AM EST MONDAY FOR
ANZ430-431-450>455.
&&
$$
SYNOPSIS...DELISI
NEAR TERM...HAYES
SHORT TERM...O`HARA
LONG TERM...DELISI/KRUZDLO
AVIATION...DELISI/HAYES
MARINE...DELISI/O`HARA
TIDES/COASTAL FLOODING...DELISI
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
944 AM EST SAT FEB 11 2012
.SYNOPSIS...
A BROAD AREA OF LOW PRESSURE ALONG THE SOUTHERN MID ATLANTIC COAST
EARLY THIS MORNING WILL CONSOLIDATE AND DEEPEN AS IT MOVES NORTHEAST
AND OUT TO SEA TODAY, AND A COLD FRONT WILL CROSS OUR AREA THIS
AFTERNOON. THERE WILL BE A STRONG NORTHWEST FLOW AND SOME COLDER AIR
IN THE WAKE OF THE FRONT. A SECONDARY COLD FRONT WILL CROSS THE AREA
LATE SUNDAY. HIGH PRESSURE WILL BUILD IN ON MONDAY, THEN TWO WEAK
SYSTEMS COULD AFFECT THE REGION DURING THE MIDDLE TO LATTER PART OF
NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SOME BANDED FEATURES ARE STARTING TO APPEAR ON RADAR AS THE BEST
MID LEVEL FRONTOGENETIC CROSSES NEW JERSEY AT THIS TIME. THE
FEATURE APPEARS TO BE PROGRESSIVE. OTHERWISE...1200 UTC SOUNDINGS
ARE SHOWING MOIST CONDITIONS THROUGH THE MID LEVELS...WITHOUT MUCH
IN THE WAY OF FORCING THROUGH MID AFTERNOON TO REMOVE IT. THIS
PROBABLY MEANS LIGHT SNOW/RAIN MAY CONTINUE INTO THE EARLY
AFTERNOON...BUT LITTLE ADDITIONAL ACCUMULATION IS EXPECTED.
TEMPERATURES PROBABLY RISE JUST A COUPLE OF DEGREES...AS ANY
MEANINGFUL CLEARING LOOKS DOUBTFUL GIVEN THE AMOUNT OF MOISTURE IN
THE COLUMN.
CONDITIONS COULD BECOME ACTIVE LATE THIS AFTERNOON AND THIS
EVENING AS THE ARCTIC FRONT ACROSS EASTERN OHIO THIS MORNING
APPROACHES. MID LEVEL LAPSE RATES WILL STEEPEN (LAPSE RATES WERE
NEAR 7 C/KM ACROSS THE GREAT LAKES WITH THE SHORT WAVE PUSHING THE
FRONT ALONG). 500 MB TEMPERATURES WERE NEAR MINUS 36 CELSIUS IN
THE MID LEVELS...AND THE LOW LEVEL TEMPERATURE GRADIENT BETWEEN
KPBZ AND KDTX WAS VERY IMPRESSIVE.
THE LATEST HRRR SHOWS AN ALMOST SQUALL-LIKE STRUCTURE MOVING
THROUGH THE PENNSYLVANIA AND EASTERN MARYLAND BY ABOUT 2200 UTC.
GIVEN THE LAPSE RATES IN THE LOW AND MID LEVELS...THIS TYPE OF
STRUCTURE LOOKS POSSIBLE. A BURST OF SNOW IS POSSIBLE WITH THE
FRONT ITSELF...AND THIS POTENTIAL WILL BE ADDRESSED LATER THIS
MORNING AND THIS AFTERNOON.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
THE UPPER TROUGH WILL CROSS THE REGION TONIGHT. A SHARP SFC COLD
FRONT WILL CROSS THE AREA THIS EVENING. IT WILL BE ACCOMPANIED BY
GUSTY WINDS...FALLING TEMPERATURES AND SCATTERED SNOW SHOWERS. A
BETTER CHC FOR THE SNOW SHOWERS WILL BE ACROSS THE DELMARVA CLOSER
TO THE VORT MAX ALONG THE H5 TROUGH. HIGH CHC OR LOW LIKELY POPS
WILL BE OVER THE DELMARVA (AND CHESTER CTY PA) WHILE LOWER CHC POPS
WILL BE OVER THE REST OF PA AND NJ. TEMPERATURES WILL PLUNGE INTO
THE TEENS OVER THE POCONOS...LEHIGH VALLEY AND NRN NJ AND INTO THE
20S ELSEWHERE. WIND CHILL VALUES WILL BE IN THE SINGLE DIGITS WITH
SOME SUB-ZERO READINGS OVER THE SRN POCONOS. WINDS WILL GUST IN THE
25 TO 35 KT RANGE TONIGHT...ESPECIALLY OVER THE SRN COUNTIES.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
THE FAIRLY SHARP MID LEVEL TROUGH AXIS WILL DEVELOP A NEGATIVE
TILT AS IT LIFTS AWAY FROM OUR AREA ON SUNDAY, AND A SECONDARY
IMPULSE WILL DROP DOWN THE BACK SIDE OF IT AROUND SUNDAY EVENING.
SURFACE PRESSURE RISES IN THE WAKE OF THE TROUGH ARE ROBUST ENOUGH
TO FORECAST LAND WIND GUSTS IN EXCESS OF 30 MPH, BUT MODEL
SOUNDINGS AREN`T PRESENTLY SHOWING A WIND ADVISORY LEVEL FLOW. THE
SECONDARY IMPULSE ALSO CARRIES SOME LESSER PRESSURE RISES IN ITS
WAKE. THE SOUNDINGS ACROSS THE NORTH ARE CAPPED AT ABOUT 7000 FT
AND WE CARRY A CYCLONIC SURFACE FLOW SUNDAY INTO SUNDAY NIGHT, SO
WE CONTINUE TO CARRY FLURRIES NORTH DURING THIS TIME FRAME.
THE MODELS THEN AGREE TO TAKE A MID LEVEL IMPULSE ACROSS THE AREA IN
THE TUESDAY TO WEDNESDAY TIME FRAME, AND THEN START TO DIVERGE ON
THE HANDLING OF ANOTHER AND POSSIBLY MORE ROBUST SYSTEM TOWARD THE
END OF THE WORK WEEK. WE MADE MODEST CHANGES WITH RESPECT TO THE
FORMER AND FOLLOWED CONTINUITY WITH RESPECT TO THE LATTER.
TEMPERATURES WILL START OFF BELOW NORMAL EARLY THIS PERIOD,
TRANSITION TO NORMAL EARLY IN THE WORK WEEK AND THEN GO ABOVE
NORMAL FOR THE LATTER PART OF THE PERIOD.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
THE LAST OF THE BANDED SNOW IS MOVING THROUGH THE KPHL METRO AREA
THIS MORNING...AND SHOULD CONTINUE TO SHRINK AS IT MOVES EAST.
THIS COULD RESULT IN LOCALLY IFR VISIBILITIES THROUGH ABOUT 1600
UTC. OTHERWISE...1200 UTC SOUNDINGS SHOW MOISTURE THROUGH THE MID
LEVELS...WITH LITTLE IN THE WAY OF PUSH TO SCOUR THE MOISTURE OUT.
WITH THIS IN MIND...THE TERMINAL FORECASTS WERE UPDATED TO INCLUDE
IFR CEILINGS FOR THROUGH ABOUT 1700 UTC. AFTER THIS...A SLOW
IMPROVEMENT IS POSSIBLE AS BOUNDARY LAYER WINDS INCREASE FROM THE
NORTH.
AN ARCTIC FRONT WILL CROSS THE AREA THIS EVENING. BASED ON WHAT IS
OCCURRING WITH THE FRONT ACROSS WESTERN PENNSYLVANIA...A SMALL
WINDOW (PERHAPS 2 HOURS) OF MVFR CONDITIONS WITH CEILINGS AND
VISIBILITIES IN SNOW SHOWERS IS POSSIBLE CENTERED AROUND 2300 UTC.
IN ADDITION...WINDS WILL SHIFT TO THE NORTHWEST AND COULD GUST TO
35 KNOTS DURING THE EVENING.
OUTLOOK...
OUTSIDE OF ANY SNOW SHOWER ACTIVITY THAT MAY OCCUR ON SUNDAY INTO
SUNDAY EVENING (ESPECIALLY NORTHWEST), WE EXPECT VFR CONDITIONS INTO
TUESDAY. THE WEAK WEATHER SYSTEM DURING THE MIDWEEK PERIOD MAY CAUSE
SOME DETERIORATION IN CONDITIONS.
&&
.MARINE...
WE WILL CONVERT THE GALE WATCH TO A WARNING AND EXTEND IT OUT UNTIL
06Z MONDAY.
LOW PRESSURE WILL DEEPEN OFF THE EAST COAST AND TRACK WELL TO OUR
EAST TODAY THROUGH SUNDAY. THE GRADIENT OVER THE WATERS WILL NOT BE
VERY STRONG TODAY...BUT WILL STRENGTHEN SIGNIFICANTLY LATER TODAY
AND REMAIN STRONG INTO EARLY NEXT WEEK. A COLD FRONT WILL CROSS THE
WATERS THIS EVENING AND THE STRONG WIND GUSTS WILL FOLLOW IT. GUSTS
TO 40 KTS ARE POSSIBLE. SCATTERED SNOW SHOWERS WITH LOWER VSBYS MAY
ACCOMPANY THE FRONT. GUSTY WINDS AND ENHANCED SEAS WILL CONTINUE
THROUGH TONIGHT.
GALES ARE EXPECTED TO LAST INTO SUNDAY, AND THEY MAY LINGER INTO
SUNDAY EVENING WITH A SECONDARY FRONT CROSSING THE AREA. AFTER
THAT, CONDITIONS SHOULD DROP TO SUB-ADVISORY AND REMAIN SO THROUGH
THE MIDDLE OF THE WEEK.
&&
.TIDES/COASTAL FLOODING...
NONE OF THE LATEST OFS PROGS ARE TAKING ANY OF THE REFERENCE GAUGES
TO WITHIN A HALF FOOT OF THE MINOR TIDAL FLOODING BENCHMARKS. NO
DEPARTURES THIS MORNING WERE MUCH IN EXCESS OF 0.5 FT. WE WILL
CONTINUE TO MONITOR TIDES IN THE EVENT THAT THE PROGS ARE UNDERDONE,
BUT ANY THREAT OF MINOR TIDAL FLOODING WILL DIMINISH ONCE WINDS COME
AROUND TO NORTHWEST. WE THEN WILL TURN OUR CONCERN TO THE POSSIBILITY
OF BLOWOUT TIDES, WHICH ALSO IS DOWNPLAYED BY OFS PROGS.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...GALE WARNING FROM 6 PM THIS EVENING TO 1 AM EST MONDAY FOR
ANZ430-431-450>455.
&&
$$
SYNOPSIS...DELISI
NEAR TERM...HAYES
SHORT TERM...O`HARA
LONG TERM...DELISI/KRUZDLO
AVIATION...DELISI/HAYES
MARINE...DELISI/O`HARA
TIDES/COASTAL FLOODING...DELISI
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
856 AM EST SAT FEB 11 2012
.SYNOPSIS...
A BROAD AREA OF LOW PRESSURE ALONG THE SOUTHERN MID ATLANTIC COAST
EARLY THIS MORNING WILL CONSOLIDATE AND DEEPEN AS IT MOVES NORTHEAST
AND OUT TO SEA TODAY, AND A COLD FRONT WILL CROSS OUR AREA THIS
AFTERNOON. THERE WILL BE A STRONG NORTHWEST FLOW AND SOME COLDER AIR
IN THE WAKE OF THE FRONT. A SECONDARY COLD FRONT WILL CROSS THE AREA
LATE SUNDAY. HIGH PRESSURE WILL BUILD IN ON MONDAY, THEN TWO WEAK
SYSTEMS COULD AFFECT THE REGION DURING THE MIDDLE TO LATTER PART OF
NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SOME BANDED FEATURES ARE STARTING TO APPEAR ON RADAR AS THE BEST
MID LEVEL FRONTOGENETIC CROSSES NEW JERSEY AT THIS TIME. THE
FEATURE APPEARS TO BE PROGRESSIVE...SO UNLESS IT SLOWS DOWN THE
WINTER WEATHER ADVISORY WILL BE ALLOWED TO EXPIRE ON TIME OR
CANCELED AT THE NEXT FORECAST UPDATE.
OTHERWISE...1200 UTC SOUNDINGS ARE SHOWING MOIST CONDITIONS
THROUGH THE MID LEVELS...WITHOUT MUCH IN THE WAY OF FORCING
THROUGH MID AFTERNOON TO REMOVE IT. THIS PROBABLY MEANS LIGHT
SNOW/RAIN MAY CONTINUE INTO THE EARLY AFTERNOON...BUT LITTLE
ADDITIONAL ACCUMULATION IS EXPECTED. TEMPERATURES PROBABLY RISE
JUST A COUPLE OF DEGREES...AS ANY MEANINGFUL CLEARING LOOKS
DOUBTFUL GIVEN THE AMOUNT OF MOISTURE IN THE COLUMN.
CONDITIONS COULD BECOME ACTIVE LATE THIS AFTERNOON AND THIS
EVENING AS THE ARCTIC FRONT ACROSS EASTERN OHIO THIS MORNING
APPROACHES. MID LEVEL LAPSE RATES WILL STEEPEN (LAPSE RATES WERE
NEAR 7 C/KM ACROSS THE GREAT LAKES WITH THE SHORT WAVE PUSHING THE
FRONT ALONG). 500 MB TEMPERATURES WERE NEAR MINUS 36 CELSIUS IN
THE MID LEVELS...AND THE LOW LEVEL TEMPERATURE GRADIENT BETWEEN
KPBZ AND KDTX WAS VERY IMPRESSIVE.
THE LATEST HRRR SHOWS AN ALMOST SQUALL-LIKE STRUCTURE MOVING
THROUGH THE PENNSYLVANIA AND EASTERN MARYLAND BY ABOUT 2200 UTC.
GIVEN THE LAPSE RATES IN THE LOW AND MID LEVELS...THIS TYPE OF
STRUCTURE LOOKS POSSIBLE. A BURST OF SNOW IS POSSIBLE WITH THE
FRONT ITSELF...AND THIS POTENTIAL WILL BE ADDRESSED LATER THIS
MORNING AND THIS AFTERNOON.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
THE UPPER TROUGH WILL CROSS THE REGION TONIGHT. A SHARP SFC COLD
FRONT WILL CROSS THE AREA THIS EVENING. IT WILL BE ACCOMPANIED BY
GUSTY WINDS...FALLING TEMPERATURES AND SCATTERED SNOW SHOWERS. A
BETTER CHC FOR THE SNOW SHOWERS WILL BE ACROSS THE DELMARVA CLOSER
TO THE VORT MAX ALONG THE H5 TROUGH. HIGH CHC OR LOW LIKELY POPS
WILL BE OVER THE DELMARVA (AND CHESTER CTY PA) WHILE LOWER CHC POPS
WILL BE OVER THE REST OF PA AND NJ. TEMPERATURES WILL PLUNGE INTO
THE TEENS OVER THE POCONOS...LEHIGH VALLEY AND NRN NJ AND INTO THE
20S ELSEWHERE. WIND CHILL VALUES WILL BE IN THE SINGLE DIGITS WITH
SOME SUB-ZERO READINGS OVER THE SRN POCONOS. WINDS WILL GUST IN THE
25 TO 35 KT RANGE TONIGHT...ESPECIALLY OVER THE SRN COUNTIES.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
THE FAIRLY SHARP MID LEVEL TROUGH AXIS WILL DEVELOP A NEGATIVE
TILT AS IT LIFTS AWAY FROM OUR AREA ON SUNDAY, AND A SECONDARY
IMPULSE WILL DROP DOWN THE BACK SIDE OF IT AROUND SUNDAY EVENING.
SURFACE PRESSURE RISES IN THE WAKE OF THE TROUGH ARE ROBUST ENOUGH
TO FORECAST LAND WIND GUSTS IN EXCESS OF 30 MPH, BUT MODEL
SOUNDINGS AREN`T PRESENTLY SHOWING A WIND ADVISORY LEVEL FLOW. THE
SECONDARY IMPULSE ALSO CARRIES SOME LESSER PRESSURE RISES IN ITS
WAKE. THE SOUNDINGS ACROSS THE NORTH ARE CAPPED AT ABOUT 7000 FT
AND WE CARRY A CYCLONIC SURFACE FLOW SUNDAY INTO SUNDAY NIGHT, SO
WE CONTINUE TO CARRY FLURRIES NORTH DURING THIS TIME FRAME.
THE MODELS THEN AGREE TO TAKE A MID LEVEL IMPULSE ACROSS THE AREA IN
THE TUESDAY TO WEDNESDAY TIME FRAME, AND THEN START TO DIVERGE ON
THE HANDLING OF ANOTHER AND POSSIBLY MORE ROBUST SYSTEM TOWARD THE
END OF THE WORK WEEK. WE MADE MODEST CHANGES WITH RESPECT TO THE
FORMER AND FOLLOWED CONTINUITY WITH RESPECT TO THE LATTER.
TEMPERATURES WILL START OFF BELOW NORMAL EARLY THIS PERIOD,
TRANSITION TO NORMAL EARLY IN THE WORK WEEK AND THEN GO ABOVE
NORMAL FOR THE LATTER PART OF THE PERIOD.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
LOW CIGS/VSBYS IN SNOW CONTINUE AT THE TERMINALS EARLY THIS MORNING.
AVIATION CONDITIONS WILL START TO IMPROVE BY THE MID-MORNING...LOW
CONFID IN WHETHER CONDITIONS TODAY WILL GET BACK TO VFR OR REMAIN
MVFR. 12Z TAFS MAY INCORPORATE CHANGES TO THE ONGOING TERMINALS. SKY
COVER WILL BE BKN-OVC TODAY WITH MOST OF THE PRECIPITATION ENDING
BEFORE NOON. A SHARP COLD FRONT CROSSES THE TERMINALS THIS EVENING
WITH WINDS SHIFTING NW AND INCREASING WITH 25-30 KT GUSTS OVERNIGHT.
SCATTERED SNOW SHOWERS AND BRIEFLY LOWER CIGS MAY ACCOMPANY THE
FRONT. VFR CONDITIONS WILL RETURN BEHIND THE FRONT.
OUTLOOK...
OUTSIDE OF ANY SNOW SHOWER ACTIVITY THAT MAY OCCUR ON SUNDAY INTO
SUNDAY EVENING (ESPECIALLY NORTHWEST), WE EXPECT VFR CONDITIONS INTO
TUESDAY. THE WEAK WEATHER SYSTEM DURING THE MIDWEEK PERIOD MAY CAUSE
SOME DETERIORATION IN CONDITIONS.
&&
.MARINE...
WE WILL CONVERT THE GALE WATCH TO A WARNING AND EXTEND IT OUT UNTIL
06Z MONDAY.
LOW PRESSURE WILL DEEPEN OFF THE EAST COAST AND TRACK WELL TO OUR
EAST TODAY THROUGH SUNDAY. THE GRADIENT OVER THE WATERS WILL NOT BE
VERY STRONG TODAY...BUT WILL STRENGTHEN SIGNIFICANTLY LATER TODAY
AND REMAIN STRONG INTO EARLY NEXT WEEK. A COLD FRONT WILL CROSS THE
WATERS THIS EVENING AND THE STRONG WIND GUSTS WILL FOLLOW IT. GUSTS
TO 40 KTS ARE POSSIBLE. SCATTERED SNOW SHOWERS WITH LOWER VSBYS MAY
ACCOMPANY THE FRONT. GUSTY WINDS AND ENHANCED SEAS WILL CONTINUE
THROUGH TONIGHT.
GALES ARE EXPECTED TO LAST INTO SUNDAY, AND THEY MAY LINGER INTO
SUNDAY EVENING WITH A SECONDARY FRONT CROSSING THE AREA. AFTER
THAT, CONDITIONS SHOULD DROP TO SUB-ADVISORY AND REMAIN SO THROUGH
THE MIDDLE OF THE WEEK.
&&
.TIDES/COASTAL FLOODING...
NONE OF THE LATEST OFS PROGS ARE TAKING ANY OF THE REFERENCE GAUGES
TO WITHIN A HALF FOOT OF THE MINOR TIDAL FLOODING BENCHMARKS. NO
DEPARTURES THIS MORNING WERE MUCH IN EXCESS OF 0.5 FT. WE WILL
CONTINUE TO MONITOR TIDES IN THE EVENT THAT THE PROGS ARE UNDERDONE,
BUT ANY THREAT OF MINOR TIDAL FLOODING WILL DIMINISH ONCE WINDS COME
AROUND TO NORTHWEST. WE THEN WILL TURN OUR CONCERN TO THE POSSIBILITY
OF BLOWOUT TIDES, WHICH ALSO IS DOWNPLAYED BY OFS PROGS.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
PAZ070-071.
NJ...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
NJZ016>020-027.
DE...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
DEZ001.
MD...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
MDZ008.
MARINE...GALE WARNING FROM 6 PM THIS EVENING TO 1 AM EST MONDAY FOR
ANZ430-431-450>455.
&&
$$
SYNOPSIS...DELISI
NEAR TERM...HAYES
SHORT TERM...O`HARA
LONG TERM...DELISI/KRUZDLO
AVIATION...DELISI/O`HARA
MARINE...DELISI/O`HARA
TIDES/COASTAL FLOODING...DELISI
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1045 AM CST SAT FEB 11 2012
.DISCUSSION...
ISSUED 1045 AM CST SAT FEB 11 2012
FORECAST GENERALLY LOOKS ON TRACK TODAY AND ONLY MINOR ADJUSTMENTS
TO THE HOURLY WEATHER ELEMENTS LIKE BUMPING UP THE WIND SPEEDS A
TAD. BLUSTERY NW WINDS OF 15 TO 25 MPH AND GUSTS OF 25 TO 35 MPH
ARE EXPECTED TODAY. HIGHS MOSTLY IN THE LOWER 20S...WITH
LAWRENCEVILLE NEAR 25F. A 1 TO 2.5 INCH SNOW COVER ALONG AND WEST
OF A MACOMB TO JACKSONVILLE LINE WILL KEEP THAT AREA A BIT COOLER
ESPECIALLY FOR LOWS TONIGHT. ALSO A LIGHT SNOW COVER LESS THAN 1
INCH FROM BLOOMINGTON TO OLNEY EAST WILL ALSO KEEP THEM A BIT
COOLER ESPECIALLY TONIGHT. NAM AND GFS BUFKIT MOMENTUM SHOWS GUSTS
IN THE UPPER 20S AND LOWER 30S KNOTS RANGE TODAY INTO EARLY
EVENING AND DROP OFF BY MID EVENING. AMPLE SUNSHINE TO PREVAIL
TODAY WITH JUST FEW TO SCATTERED CUMULUS CLOUDS EXPECTED OVER
EASTERN IL WHERE MOSTLY SUNNY SKIES EXPECTED AND THESE CLOUDS HAVE
JUST RECENTLY DEVELOPED BY LATE MORNING.
WIND CHILLS CURRENTLY IN THE SINGLE DIGITS ABOVE ZERO...EXCEPT
ZERO TO 5 BELOW ZERO FROM BLOOMINGTON TO CHAMPAIGN NE WILL MOSTLY
STAY IN THE SINGLE DIGITS TODAY...SO WILL FEEL LIKE ONE OF THE
COLDER DAYS SO FAR DURING THIS RELATIVELY MILD WINTER OVER CENTRAL
IL. STRONG 1046 MB ARCTIC HIGH PRESSURE OVER THE CENTRAL PLAINS
EDGE CLOSER TO THE MS VALLEY THROUGH SUNDAY MORNING AND KEEP IL
DRY AND COLD THIS WEEKEND.
HUETTL
&&
.AVIATION...
ISSUED 525 AM CST SAT FEB 11 2012
STRONG HIGH PRESSURE CENTERED IN SOUTH DAKOTA WILL BE THE MAIN
WEATHER INFLUENCE IN CENTRAL AND EASTERN IL TODAY AND SUNDAY.
PLENTY OF SUBSIDENCE AND DRY AIR WILL RESULT IN VFR CONDITIONS THE
NEXT 24 HOURS. WILL GO WITH A CLEAR SKY AT ALL TAF SITES AS A
RESULT. THE RUC WAS TRYING TO INDICATE SOME SCT-BKN CU NEAR KCMI
AND POINTS EAST FROM LAKE MICHIGAN LATE THIS MORNING. HOWEVER THE
FETCH DOWN THE LAKE SHOULD BECOME MORE NORTH-NORTHWESTERLY...WHICH
WOULD KEEP ANY CLOUDS EAST OF THE AREA.
THE WIND HAS RELAXED A LITTLE BIT IN PARTS OF CENTRAL IL EARLY
THIS MORNING...DESPITE A CONTINUED TIGHT PRESSURE GRADIENT. I
EXPECT THIS TO INCREASE AGAIN BY LATE MORNING AS THE LOWER
ATMOSPHERE STARTS TO MIX. BUFKIT SOUNDINGS AND MOMENTUM TRANSFER
POINT TO GUSTS IN THE 20-28KT RANGE TODAY...SO WILL FOLLOW THAT
GUIDANCE CLOSELY.
MILLER
&&
.PREV DISCUSSION...
ISSUED 322 AM CST SAT FEB 11 2012
COLD AIR MOVING INTO THE REGION BEHIND A FRONTAL SYSTEM AND A DEEP
UPPER TROF...FINALLY BRINGING SOME COLDER AND MORE SEASONABLE TEMPS
INTO THE MIDWEST FOR THE WEEKEND. HIGH PRESSURE BUILDING IN OVER
THE NORTHERN PLAINS...AND CLEARING SKIES SCOURING OUT THE REMNANT
FLURRIES OVER ILX. MAIN ISSUES FOR THE FORECAST REVOLVE AROUND THE
NEXT SYSTEM ON APPROACH FOR MON/TUES. SOME MINOR TIMING ISSUES
AFFECT THE ONSET OF SNOW ON MONDAY...BUT THE ABUNDANCE OF COLD AIR HAS
EFFECTIVELY REMOVED MOST CONCERNS ABOUT PRECIP TYPE. FORECAST
REMAINS A SLIGHT BLEND...BUT MOST OF THE PARAMETERS ARE IN
RELATIVE AGREEMENT. NEXT ISSUES IN THE FORECAST WILL BE THE TEMPS
ON THE OTHER SIDE OF THE SNOW AT THE END OF THE WORK WEEK. MOS
NUMBERS LOOK A LITTLE TOO WARM CONSIDERING ANOTHER SHOT OF COLD
AIR MOVING IN AT MID LEVELS.
SHORT TERM...TODAY AND TOMORROW...
COLD. TEMPS CHILLY THIS MORNING IN THE TEENS ACROSS CENTRAL
ILLINOIS...AND BRISK NORTHERLY FLOW WILL KEEP THE HIGHS
CONSIDERABLY COOLER...HIGHS ONLY CLIMBING INTO THE
20S...REGARDLESS OF AMPLE SUNSHINE. SAME CONTINUES TONIGHT...WITH
CLEAR SKIES AND AN ARCTIC AIRMASS PUSHING THE TEMPS DOWN INTO THE
SINGLE DIGITS AND AROUND 10F. HIGH PRESSURE RIDGE SHIFTS ENOUGH TO
BRING WINDS TO A MORE WESTERLY DIRECTION FOR TOMORROW...AND TEMPS
WILL CLIMB BACK UP TO UPPER 20S...AND DROP INTO THE TEENS SUN
NIGHT IN ADVANCE OF THE CLOUDS ASSOCIATED WITH THE NEXT DEVELOPING
SYSTEM MOVING OUT OF THE WEST.
LONG TERM...MONDAY THROUGH FRIDAY...
WAVE MOVING INTO THE PAC NW WILL PUSH OVER THE ROCKIES AND INTO
THE MIDWEST MID-MONDAY AND BRING THE NEXT CHANCE FOR SNOW. MODELS
IN ENOUGH ARGUMENT TO GO CATEGORICAL AT THIS POINT...WITH THE GFS
JUST SLIGHTLY AHEAD...BRINGING IN THE SNOW ACROSS THE WRN HALF OF
THE CWA BY NOON. BETTER CHANCES STILL LATER MONDAY AFTERNOON AND
MON EVENING INTO THE OVERNIGHT. HPC AND PREV FORECAST RATHER
CONSISTENT IN THE 1 TO 2 INCH STORM TOTALS. SLR AROUND 13
CONSISTENT WITH CLIMATOLOGY...AND FORECAST SOUNDINGS ACROSS THE
BOARD SHOWING PLENTY OF MOISTURE TO WORK WITH THROUGHOUT THE
COLUMN MON LATE AFTERNOON. SNOW TAPERING OFF DURING THE DAY ON
TUESDAY. ANOTHER SYSTEM QUICK ON ITS HEELS MOVING OUT OF THE
ROCKIES EARLY THU. CURIOUS AGREEMENT IN THE EXTENDED BTWN THE GFS
AND THE ECMWF...AND POPS WILL COME UP IF THE AGREEMENT
CONTINUES...EVEN AT DAY 6. HOWEVER...THE TRACK OF THE GFS IS A BIT
FURTHER SOUTH WHICH WOULD MAKE A RATHER SIG DIFFERENCE FOR AREAS
NORTH OF ILLINOIS RIVER VALLEY AS FAR AS IMPACT. TEMPS FOR THU AND
FRI A BIT WARM AT THIS POINT. CONCERNED THAT THE ECMWF IS BRINGING
THROUGH SOME RATHER COLD AIR AT MID LEVELS AND PLENTY OF
CLOUDS...NOT CONVINCED THAT THE SFC TEMPS WILL GET THAT WARM AND
HAVE PULLED THEM DOWN SLIGHTLY. THIS MISREPRESENTATION WILL DEF
HAVE IMPACT ON THE PRECIP TYPE. NOT SUPER CONFIDENT JUST YET IN
THE EXTENDED.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
525 AM CST SAT FEB 11 2012
.DISCUSSION...
ISSUED 322 AM CST SAT FEB 11 2012
COLD AIR MOVING INTO THE REGION BEHIND A FRONTAL SYSTEM AND A DEEP
UPPER TROF...FINALLY BRINGING SOME COLDER AND MORE SEASONABLE TEMPS
INTO THE MIDWEST FOR THE WEEKEND. HIGH PRESSURE BUILDING IN OVER
THE NRN PLAINS...AND CLEARING SKIES SCOURING OUT THE REMNANT
FLURRIES OVER ILX. MAIN ISSUES FOR THE FORECAST REVOLVE AROUND THE
NEXT SYSTEM ON APPROACH FOR MON/TUES. SOME MINOR TIMING ISSUES
AFFECT THE ONSET OF SNOW ON MONDAY...BUT THE ABUNDANCE OF COLD AIR HAS
EFFECTIVELY REMOVED MOST CONCERNS ABOUT PRECIP TYPE. FORECAST
REMAINS A SLIGHT BLEND...BUT MOST OF THE PARAMETERS ARE IN
RELATIVE AGREEMENT. NEXT ISSUES IN THE FORECAST WILL BE THE TEMPS
ON THE OTHER SIDE OF THE SNOW AT THE END OF THE WORK WEEK. MOS
NUMBERS LOOK A LITTLE TOO WARM CONSIDERING ANOTHER SHOT OF COLD
AIR MOVING IN AT MID LEVELS.
SHORT TERM...TODAY AND TOMORROW...
COLD. TEMPS CHILLY THIS MORNING IN THE TEENS ACROSS CENTRAL
ILLINOIS...AND BRISK NORTHERLY FLOW WILL KEEP THE HIGHS
CONSIDERABLY COOLER...HIGHS ONLY CLIMBING INTO THE
20S...REGARDLESS OF AMPLE SUNSHINE. SAME CONTINUES TONIGHT...WITH
CLEAR SKIES AND AN ARCTIC AIRMASS PUSHING THE TEMPS DOWN INTO THE
SINGLE DIGITS AND AROUND 10F. HIGH PRESSURE RIDGE SHIFTS ENOUGH TO
BRING WINDS TO A MORE WESTERLY DIRECTION FOR TOMORROW...AND TEMPS
WILL CLIMB BACK UP TO UPPER 20S...AND DROP INTO THE TEENS SUN
NIGHT IN ADVANCE OF THE CLOUDS ASSOCIATED WITH THE NEXT DEVELOPING
SYSTEM MOVING OUT OF THE WEST.
LONG TERM...MONDAY THROUGH FRIDAY...
WAVE MOVING INTO THE PAC NW WILL PUSH OVER THE ROCKIES AND INTO
THE MIDWEST MID-MONDAY AND BRING THE NEXT CHANCE FOR SNOW. MODELS
IN ENOUGH ARGUMENT TO GO CATEGORICAL AT THIS POINT...WITH THE GFS
JUST SLIGHTLY AHEAD...BRINGING IN THE SNOW ACROSS THE WRN HALF OF
THE CWA BY NOON. BETTER CHANCES STILL LATER MONDAY AFTERNOON AND
MON EVENING INTO THE OVERNIGHT. HPC AND PREV FORECAST RATHER
CONSISTENT IN THE 1 TO 2 INCH STORM TOTALS. SLR AROUND 13
CONSISTENT WITH CLIMATOLOGY...AND FORECAST SOUNDINGS ACROSS THE
BOARD SHOWING PLENTY OF MOISTURE TO WORK WITH THROUGHOUT THE
COLUMN MON LATE AFTERNOON. SNOW TAPERING OFF DURING THE DAY ON
TUESDAY. ANOTHER SYSTEM QUICK ON ITS HEELS MOVING OUT OF THE
ROCKIES EARLY THU. CURIOUS AGREEMENT IN THE EXTENDED BTWN THE GFS
AND THE ECMWF...AND POPS WILL COME UP IF THE AGREEMENT
CONTINUES...EVEN AT DAY 6. HOWEVER...THE TRACK OF THE GFS IS A BIT
FURTHER SOUTH WHICH WOULD MAKE A RATHER SIG DIFFERENCE FOR AREAS
NORTH OF ILLINOIS RIVER VALLEY AS FAR AS IMPACT. TEMPS FOR THU AND
FRI A BIT WARM AT THIS POINT. CONCERNED THAT THE ECMWF IS BRINGING
THROUGH SOME RATHER COLD AIR AT MID LEVELS AND PLENTY OF
CLOUDS...NOT CONVINCED THAT THE SFC TEMPS WILL GET THAT WARM AND
HAVE PULLED THEM DOWN SLIGHTLY. THIS MISREPRESENTATION WILL DEF
HAVE IMPACT ON THE PRECIP TYPE. NOT SUPER CONFIDENT JUST YET IN
THE EXTENDED.
&&
.AVIATION...
ISSUED 525 AM CST SAT FEB 11 2012
STRONG HIGH PRESSURE CENTERED IN SOUTH DAKOTA WILL BE THE MAIN
WEATHER INFLUENCE IN CENTRAL AND EASTERN IL TODAY AND SUNDAY.
PLENTY OF SUBSIDENCE AND DRY AIR WILL RESULT IN VFR CONDITIONS THE
NEXT 24 HOURS. WILL GO WITH A CLEAR SKY AT ALL TAF SITES AS A
RESULT. THE RUC WAS TRYING TO INDICATE SOME SCT-BKN CU NEAR KCMI
AND POINTS EAST FROM LAKE MICHIGAN LATE THIS MORNING. HOWEVER THE
FETCH DOWN THE LAKE SHOULD BECOME MORE NORTH-NORTHWESTERLY...WHICH
WOULD KEEP ANY CLOUDS EAST OF THE AREA.
THE WIND HAS RELAXED A LITTLE BIT IN PARTS OF CENTRAL IL EARLY
THIS MORNING...DESPITE A CONTINUED TIGHT PRESSURE GRADIENT. I
EXPECT THIS TO INCREASE AGAIN BY LATE MORNING AS THE LOWER
ATMOSPHERE STARTS TO MIX. BUFKIT SOUNDINGS AND MOMENTUM TRANSFER
POINT TO GUSTS IN THE 20-28KT RANGE TODAY...SO WILL FOLLOW THAT
GUIDANCE CLOSELY.
MILLER
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1150 PM CST FRI FEB 10 2012
.DISCUSSION...
1150 PM CST
HAVE UPGRADED PORTER COUNTY TO A BLIZZARD WARNING FOR THE
REMAINDER OF THE OVERNIGHT HOURS. AFTER MAKING NUMEROUS CALLS TO
LAW ENFORCEMENT AND PUBLIC ACROSS NORTHERN PORTER COUNTY REALIZED
THAT CONDITIONS WERE EVEN MORE SEVERE THAN PREVIOUSLY THOUGHT.
VISBILITIES HAVE BEEN REPORTED TO BE LESS THAN ONE CAR LENGTH AND
ONE PERSON WAS QUOTED AS SAYING THIS STORM MAKES LAST YEARS
BLIZZARD SEEM LIKE NOTHING. COMBINATION OF EXCELLATION OF WINDS
WITHIN THE CONVERGENCE BAND AND CONVECTIVELY MIXING DOWN WIND
GUSTS AM CONFIDENT THAT THE WIND SPEED AND VISIBILITY CRITERIA FOR
A BLIZZARD WILL BE MET. REPORTS OF 8-10 INCHES HAVING FALLEN SO
FAR WITH SEVERAL MORE HOURS OF INTENSE SNOW WITH RATES OF 2-4
INCHES PER HOUR EXPECTED. STORM TOTALS OF A FOOT AND A HALF STILL
LOOK LIKE A DISTINCT POSSIBILITY.
IN ADDITION...BURNS HARBOR JUST CAME IN WITH A 52 KT GUST AT 0521Z
UNDERNEATH THE INTENSE LES BAND. STILL THINK THERE IS A POSSIBILITY
OF ISOLATED THUNDERSTORMS OVERNIGHT WITHIN THE BAND AS WELL GIVEN
THE EXTREME LAKE INDUCED INSTABILITY.
IZZI
&&
.PREV DISCUSSION...
1008 PM CST
REMAINING ADVISORIES HAVE BEEN ALLOWED TO EXPIRE THIS
EVENING...HAVE CONTINUED LAKE EFFECT WARNING FOR LAKE AND PORTER
IN INDIANA...AND HAVE UPGRADED JASPER COUNTY TO A LAKE EFFECT
WARNING.
LATEST RADAR ANALYSIS CONTINUES TO SHOW LAKE EFFECT SNOW SHOWERS
DEVELOPING BUT PRIMARILY REMAINING IN INDIANA...WITH THE MORE
SYNOPTICALLY DRIVEN SNOW HAVING SINCE DIMINISHED OVER THE LAST
COUPLE OF THE HOURS. LATEST TRENDS IN LINE WITH CURRENT HEADLINES
IN PLACE WITH LAKE EFFECT SNOW SHOWERS CONTINUING OVERNIGHT. OVER
THE LAST COUPLE OF HOURS...A STRONGER AND MORE DEFINED SNOW BAND
HAS DEVELOPED AND SITUATED ITSELF OVER LAKE AND PORTER COUNTIES IN
INDIANA. LATEST RUC ANALYSIS SHOWING CONDITIONS OVER THE LAKE HAVE
IMPROVED SIGNIFICANTLY IN REGARDS TO SNOW POTENTIAL WITH 850 DELTA
TS IN UPWARDS OF 18C AND STRONG CONVERGENCE SETTING UP ACROSS THE
LAKE...AS ALSO INDICATED BY LATEST SURFACE/MARINE OBS. LATEST
GUIDANCE IN GOOD AGREEMENT WITH CONDITIONS OVER THE LAKE TO
CONTINUE IMPROVING OVER THE NEXT SEVERAL HOURS. THIS COINCIDING
WITH A LONG FETCH OVER THE LAKE AND DECENT INVERSION
HEIGHTS...SHOULD ALLOW FOR CONTINUED DEVELOPMENT INTO THE EARLY
MORNING HOURS ON SATURDAY. SHORT RANGE GUIDANCE IS INDICATING THAT
THIS BAND WILL REMAIN SITUATED OVER THE LAKE/PORTER COUNTY LINE
BEFORE LOW LEVEL/BOUNDARY LAYER FLOW SHIFTS MORE EAST AND HELPS
STEER IT MORE OVER PORTER COUNTY BY THE EARLY MORNING HOURS. HAVE
INCREASE SNOW AMOUNTS ACROSS JASPER COUNTY AS LATEST RADAR RETURNS
HAVE BEEN REACHING THE NORTHERN PORTIONS OF THE COUNTY. WITH
CONDITIONS EXPECTED TO ONLY BECOME MORE FAVORABLE TONIGHT AND WITH
STRONG FLOW IN PLACE...PORTIONS OF JASPER COUNTY SHOULD SEE
WARNING CRITERIA SNOW. FORECASTED SNOW AMOUNTS CONTINUE TO BE IN
LINE WITH THE HIGHEST AMOUNTS STILL EXPECTED WITHIN PORTER
COUNTY...BEFORE THIS BAND SHIFTS EAST WITH TIME SATURDAY MORNING.
RODRIGUEZ
//PREV DISCUSSION...
355 PM CST
THE ONGOING SNOW EVENT WILL TRANSITION TO MORE OF A TRUE LAKE
EFFECT SNOW STORM INTO MAINLY NORTHWEST INDIANA THIS EVENING. THE
COMBINATION OF THE SNOW...GUSTY WINDS...AND FALLING TEMPERATURES
FREEZING SOME OF THE EARLIER MELTED SNOWFALL WILL CONTINUE TO
CREATE IMPACTS FOR A LARGE PART OF THE AREA INTO EARLY
EVENING...AND NORTHWEST INDIANA ALL NIGHT LONG.
LATE THIS AFTERNOON THROUGH SATURDAY
THE ARCTIC FRONT WILL CONTINUE TO MOVE SOUTHWARD...CLEARING THE
AREA BY EARLY EVENING. NORTHERLY WINDS GUSTING UP TO 35 MPH HAVE
USHERED IN A MUCH COLDER AIR ACROSS THE AREA WITH WIND CHILLS
HAVING DROPPED TO NEAR ZERO ALREADY ALONG THE WI STATE LINE. WATER
VAPOR SATELLITE SHOWS THE MAIN UPPER LEVEL WAVE MOVING OVER THE
AREA...WHICH COMBINED WITH THE STEEP LOW-LEVEL LAPSE RATES WILL
CONTINUE GENERAL SNOWFALL ACROSS THE IL AREA THROUGH EARLY TO MID
EVENING. SOME LAKE ENHANCEMENT IMMEDIATELY NEAR THE LAKE MICHIGAN
SHORE IS LIKELY.
A TRUE LAKE EFFECT BAND HAS ALREADY DEVELOPED JUST OFFSHORE BASED
ON KMKX/TORD RADAR SIGNATURES. THIS WILL CONTINUE TO BECOME
BETTER ESTABLISHED INTO COOK AND NORTHWEST LAKE COUNTIES THROUGH
EARLY EVENING BASED ON SHORT TERM GUIDANCE DEPICTION OF LOW-LEVEL
CONVERGENCE AND INSTABILITY. BY 9 PM AND AFTER...THE
EMPHASIS WILL BE SHIFTING INTO FAR SOUTHEAST COOK AND LAKE
COUNTIES WITH HIGH CONFIDENCE IN SHORT TERM MODELS. IT IS POSSIBLE
THE ADVISORY WILL NEED TO BE EXTENDED FOR COOK COUNTY AFTER 9
PM...AS SNOWFALL RATES WITHIN SUCH A BAND ARE LIKELY TO BE HEAVY
WITH EFFICIENT SNOW-TO-LIQUID RATIOS AND THE PRESENT INSTABILITY.
THE STRONG TEMPERATURE DIFFERENCE BETWEEN THE AIR MOVING OVER THE
LAKE AND THE 38 TO 43 DEGREE OPEN WATER LAKE TEMPERATURES ACROSS
THE SOUTHERN HALF WILL HELP TO GENERATE LAKE-INDUCED CAPE VALUES
TO 500 J/KG BY AFTER 9 PM...LASTING THROUGH THE OVERNIGHT AND
SHIFTING SLOWLY EAST. FAR SOUTHEAST COOK COUNTY COULD SEE TOTAL
SNOWFALL AMOUNTS APPROACH SIX INCHES.
THE CONVERGENT AXIS WILL ROTATE EAST FOCUSING INTO LAKE AND PORTER
COUNTIES OVERNIGHT. THE RATIOS SHOULD CONTINUE TO INCREASE...WITH
THE FAVORABLE SNOW GROWTH ZONE LOCATED BELOW THE EQUILIBRIUM
LEVEL. THE HIGHER WIND SPEEDS ARE LIKELY TO BREAK UP THE FLAKES
SOME...BUT THE HEAVY RATES SHOULD STILL COMPENSATE FOR THAT.
SIMULATED REFLECTIVITY ON SHORT TERM GUIDANCE ALSO RAMPS UP DURING
THAT TIME. THE TREND WITH ALMOST ALL HIGH RESOLUTION GUIDANCE WAS
TO SHIFT THIS EAST SLIGHTLY...REALLY FOCUSING INTO PORTER COUNTY
OVERNIGHT. THE HIGHEST SNOWFALL AMOUNTS TOWARD TEN INCHES IN OUR
FORECAST ARE FOCUSED IN EASTERN LAKE AND PORTER COUNTIES. THE
WIDTH OF THE BAND LOOKS TO NARROW AS IT SHIFTS EAST THOUGH...SO
AGAIN SOME UNCERTAINTY CONTINUES DUE TO THE LIKELY TIGHT GRADIENT
IN SNOWFALL. GIVEN THE LARGE VALUES OF LOW-LEVEL INSTABILITY
PRESENT...SEE NO REASON WHY SOME HIGHER AMOUNTS IN EXCESS OF TEN
INCHES TOWARDS 15 INCHES WOULD NOT BE OBSERVED IF THE BAND WERE
TO BE AS SLOW MOVING AFTER 9 PM AS FORECAST. WINDS GUSTING TO 40
MPH OR HIGHER ARE FAVORED BY OVERNIGHT IN NORTHWEST INDIANA DUE TO
THE LONG FRICTIONLESS FETCH OFF THE LAKE OF THE WIND COMPONENT AND
THE ENHANCED MIXING. THAT WILL AID IN NEAR WHITEOUT CONDITIONS AT
TIMES ACROSS NAMELY LAKE AND PORTER COUNTIES.
OVERALL NO CHANGES MADE TO THE GOING HEADLINES AT THIS TIME. THE
TIMING OF SNOW DEPARTURE IN PORTER COUNTY LOOKS TO BE BETWEEN 8 AM
AND NOON ON SATURDAY...SO THE TIMING OF ENDING THE HEADLINES LOOKS
GOOD. CLEARING TONIGHT HAS BEEN SLOWED IN THE FORECAST...BUT STILL
A STRONG DRY PUSH SHOULD LEAD TO MOST AREAS SEEING SUN BY
DAYBREAK SATURDAY.
MTF
SUNDAY THROUGH FRIDAY
PRIMARY CONCERN IS WHAT IS LOOKING TO BE A LONG DURATION LIGHT SNOW
EVENT ON MONDAY INTO EARLY TUESDAY. GENERALLY STAYED CLOSE TO BLEND
OF GUIDANCE AND PREVIOUS FORECAST THEREAFTER DUE TO LARGE MODEL
DIFFERENCES AND UNCERTAINTY.
SUNDAY THROUGH TUESDAY...
AFTER COLD START TO SUNDAY ON NORTHERN EDGE OF LARGE OF HIGH
PRESSURE...FULL SUN AND H85 TEMPERATURES WARMING TO -6 OR SO SHOULD
ALLOW RECOVERY TO 20S TO AROUND 30 DEGREES...WITH LOW 30S IN
DOWNTOWN CHICAGO. LIMITING FACTOR WILL BE NEW...DEEP SNOW COVER OVER
NORTHERN PORTIONS OF NW INDIANA...SO EXPECTING MID 20S THERE. IN
GENERAL...HIGH TEMPERATURES ARE CLOSE TO MOS GUIDANCE. ON SUNDAY
NIGHT...SHOULD BE UNDER RIDGE AXIS AND WITH CLEAR
SKIES AND DIMINISHED WINDS...TEMPERATURES WILL LIKELY FALL TO NEAR
OR BELOW NORMAL LEVELS DESPITE WARMING ALOFT. COLDEST TEMPERATURES
AGAIN EXPECTED FOR DEEP SNOW COVER AREA IN NORTHWEST INDIANA...WHERE
I WENT BELOW GUIDANCE AND FORECASTED LOW TEENS IN PORTER COUNTY.
CLOUDS WILL LIKELY INCREASE TOWARD DAYBREAK ACROSS NORTHWEST AND
NORTH CENTRAL ILLINOIS...SO TEMPERATURE DROP MAY SLOW OR STOP AFTER
INITIAL QUICK FALL AFTER DARK.
ON MONDAY...HIGH PRESSURE RIDGE WILL LOSE INFLUENCE OVER AREA AS WE
ENTER A PERSISTENT ISENTROPIC ASCENT/WARM ADVECTION
REGIME...ALLOWING INCREASE IN CLOUD COVER FIRST AND THEN
OVERSPREADING OF WIDESPREAD LIGHT PRECIPITATION. AFTER LATEST ECMWF
CAME IN A BIT SLOWER WITH PRECIP...SOME CONCERNS THAT POPS MAY HAVE
TO BE TRIMMED BACK/SLOWED SOME IN NORTHERN ILLINOIS MONDAY MONDAY MORNING
THROUGH NOON. NONETHELESS...AFOREMENTIONED ISENTROPIC ASCENT ALONG
WITH SOME MODEST MID AND UPPER LEVEL SUPPORT FROM MIDLEVEL TROUGH
PIVOTING THROUGH UPPER MIDWEST WILL BRING ENOUGH OMEGA THROUGH
SATURATED COLUMN FOR DECENT SNOW CRYSTAL GROWTH. COLD START TO DAY
PLUS H85 TEMPERATURES REMAINING AT -5C OR LESS THROUGH THE EVENT
WILL ENSURE PRECIP FALLS AS ALL SNOW. AFTERNOON TEMPS SHOULD TOP OUT
NEAR OR SLIGHTLY ABOVE 30F. BASED ON CURRENT PROGGED TRACK OF H5
TROUGH...BEST FORCING LOOKS LIKE IT WILL LINE UP CLOSER TO WISCONSIN
BORDER...BUT GOOD MODEL AGREEMENT LENT ENOUGH CONFIDENCE IN
WIDESPREAD PRECIP FOR ENTIRE CWA TO RAISE POPS TO LIKELY ACROSS THE
AREA INTO MONDAY NIGHT...TAPERING OFF OVERNIGHT INTO TUESDAY.
OVERALL...LOOKING LIKE A LIGHT QPF EVENT...PROBABLY STAYING BELOW
0.20" LE. THUS IN ALL LIKELIHOOD...IT WONT BE A BIG SNOW EVENT...BUT
POTENTIAL EXISTS FOR A COUPLE INCHES FOR AT LEAST A PORTION OF
CWA...WITH RATIOS SLIGHTLY ABOVE 10:1. HAVE LINGERING SLIGHT POPS ON
TUESDAY DUE TO UPPER TROUGH AXIS STAYING NEARBY...WITH TEMPERATURES
MODERATING A BIT MORE.
WEDNESDAY THROUGH FRIDAY...
POLAR VORTEX FULLY RETREATS INTO NORTHERN
CANADA...BRINGING US BACK TO A ZONAL...PACIFIC DOMINATED JET STREAM
PATTERN...ALLOWING TEMPERATURES TO WARM BACK ABOVE NORMAL LEVELS.
WARMING COULD BE LIMITED BY LINGERING SNOW COVER...BUT 40S ARE
CERTAINLY POSSIBLE DURING THE PERIOD...WITH H85 TEMPS WARMING TO AT
OR ABOVE 0C. AS MENTIONED...HOWEVER...LARGE MODEL DIFFERENCES AND
UNCERTAINTY ON MIDLEVEL AND SURFACE FEATURES...WITH ECMWF BRINGING
MIDLEVEL LOW AND SURFACE REFLECTION ACROSS AREA WEDNESDAY INTO
THURSDAY...WHILE GFS HAS A DRY LOOK TO IT. HAVE SLIGHT TO LOW END
CHANCE POPS FROM ALL BLEND DURING THIS PERIOD AND A RAIN OR SNOW
MENTION DUE TO MARGINAL AT BEST THERMAL PROFILE.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* NORTH-NORTHWEST WINDS GUSTING 25-30 KT THROUGH MUCH OF THE NIGHT
WHILE POSSIBLY EASING TO 20-25 KT IN THE MORNING.
MDB
//DISCUSSION...UPDATED 06Z...
VERY WELL ORGANIZED NORTH-SOUTH LAKE EFFECT SNOW BAND CONTINUES TO
BRING VERY HEAVY SNOW IN THE NORTHWEST INDIANA. GYY REMAINS JUST
TO THE WEST OF THE BAND WITH PERIODS OF LIGHT SNOW BUT THE BAND
DOES CONTINUE TO WOBBLE EAST AND WEST SLIGHTLY KEEPING THE
POTNEITAL FOR SHORT PERIODS OF MORE INTENSE SNOWFALL TO THE
TERMINAL OF THE SEVERAL HOURS. THE BAND WILL LIKELY BEGIN TO SHIFT
MORE TO THE EAST OVERNIGHT ALLOWING SNOW TO END AT GYY...BUT IT IS
NOT CLEAR WHEN EXACTLY THIS WILL OCCUR. NORTHWEST WINDS GUSTING
ANYWHERE FROM 30 TO NEAR 40 KT AT TIMES WILL CAUSE BLOWING AND
DRIFTING AND KEEP VSBY LIMITED EVEN WHEN SNOW IS NOT FALLING.
ELSEHWERE...VFR HAS SPREAD ACROSS THE NORTHERN ILLINOIS TERMINALS
AND WILL CONTINUE OVERNIGHT. NORTH-NORTHWEST WINDS CONTINUE TO
GUST INTO THE 25-30 KT RANGE AT THE CHI METRO TERMINALS THANKS TO
TIGHT PRESSURE GRADIENT CLOSER TO THE LAKE. SPEEDS MAY EASE OFF A
BIT BUT LIKELY REMAIN GUSTY SATURDAY MORNING WHILE TURNING A BIT
MORE WESTERLY. GUSTS TO AROUND 25 KT ARE EXPECTED DURING THE
AFTERNOON. VFR CONDITIONS EXPECTED TO PREVAIL WITH AN UPPER LEVEL
WAVE BRINGING SOME MID CLOUD COVER AT TIMES DURING THE DAY. THE
VERY DRY LOW LEVELS SHOULD PRECLUDE ANY STRATO CU DEVELOPMENT. WINDS
WILL EASE SOMEWHAT SATURDAY EVENING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN NORTH-NORTHWEST WINDS GUSTING 25-30 KT
THROUGH MUCH OF THE NIGHT BUT LOW-MEDIUM CONFIDENCE IN GUST
SPEEDS SATURDAY MORNING AND AFTERNOON.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...VFR.
MONDAY/TUESDAY...LIGHT SNOW LIKELY WITH IFR POSSIBLE.
WEDNESDAY...VFR.
THURSDAY...CHANCE OF RAIN AND SNOW.
MDB
&&
.MARINE...
156 PM CST
THE MAIN CONCERNS CONTINUE TO FOCUS ON THE STRONG WINDS ACROSS LAKE
MICHIGAN TONIGHT INTO SATURDAY. THE STRONG SURFACE COLD FRONT IS
MOVING ACROSS THE SOUTHERN TIP OF LAKE MICHIGAN EARLY THIS
AFTERNOON. I EXPECT NORTHERLY GALE FORCE WINDS AROUND 35 KNOTS IN
THE WAKE OF THIS FRONT. AS VERY COLD AIR CONTINUES TO SPILL OVER THE
LAKE THIS EVENING...A FAVORABLE THERMODYNAMIC SETUP WILL OCCUR FOR A
BANDS OF INTENSE LAKE EFFECT SNOW TO DEVELOP. THERE IS ALSO A GOOD
POSSIBILITY THAT AS SOME AREAS ACROSS THE SOUTHERN END OF THE LAKE
MAY SEE GALES INCREASE TO 40 KT FOR A PERIOD TONIGHT AS THESE
CONVERGENT BANDS OF SNOW DEVELOP. THESE STRONG WINDS WILL LIKELY
ALSO AFFECT THE INDIANA NEAR SHORE WATERS.
WINDS WILL ABATE SOME ON SATURDAY. HOWEVER...THE PRESSURE GRADIENT
WILL REMAIN FAIRLY TIGHT ACROSS THE LAKE AS HIGH PRESSURE DROPS OUT
OF SOUTHERN CANADA AND BUILDS ACROSS THE LOWER AND MIDDLE MISSOURI
RIVER VALLEY. THEREFORE...EXPECT NORTHWEST WINDS TO 30 KT TO
CONTINUE ON SATURDAY AND SATURDAY NIGHT. THIS SURFACE HIGH WILL
BUILD EASTWARD ACROSS THE OHIO VALLEY ON SUNDAY AND SUNDAY NIGHT.
ONCE THIS OCCURS THE WINDS WILL BECOME WEST SOUTHWESTERLY BY MONDAY.
WIND SPEEDS WILL DIMINISH INTO MONDAY.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...BLIZZARD WARNING...INZ002 UNTIL 9 AM SATURDAY.
LAKE EFFECT SNOW WARNING...INZ001 UNTIL 4 AM SATURDAY.
LAKE EFFECT SNOW WARNING...INZ011 UNTIL 9 AM SATURDAY.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 AM
SATURDAY.
GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 UNTIL 6
AM SATURDAY.
GALE WARNING...ILLINOIS NEARSHORE WATERS UNTIL 4 AM SATURDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...4 AM SATURDAY TO 6
AM SUNDAY.
GALE WARNING...INDIANA NEARSHORE WATERS UNTIL 10 AM SATURDAY.
SMALL CRAFT ADVISORY...LMZ743-LMZ744-LMZ745...10 AM SATURDAY TO
2 PM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1100 PM CST FRI FEB 10 2012
.DISCUSSION...
1008 PM CST
REMAINING ADVISORIES HAVE BEEN ALLOWED TO EXPIRE THIS
EVENING...HAVE CONTINUED LAKE EFFECT WARNING FOR LAKE AND PORTER
IN INDIANA...AND HAVE UPGRADED JASPER COUNTY TO A LAKE EFFECT
WARNING.
LATEST RADAR ANALYSIS CONTINUES TO SHOW LAKE EFFECT SNOW SHOWERS
DEVELOPING BUT PRIMARILY REMAINING IN INDIANA...WITH THE MORE
SYNOPTICALLY DRIVEN SNOW HAVING SINCE DIMINISHED OVER THE LAST
COUPLE OF THE HOURS. LATEST TRENDS IN LINE WITH CURRENT HEADLINES
IN PLACE WITH LAKE EFFECT SNOW SHOWERS CONTINUING OVERNIGHT. OVER
THE LAST COUPLE OF HOURS...A STRONGER AND MORE DEFINED SNOW BAND
HAS DEVELOPED AND SITUATED ITSELF OVER LAKE AND PORTER COUNTIES IN
INDIANA. LATEST RUC ANALYSIS SHOWING CONDITIONS OVER THE LAKE HAVE
IMPROVED SIGNIFICANTLY IN REGARDS TO SNOW POTENTIAL WITH 850 DELTA
TS IN UPWARDS OF 18C AND STRONG CONVERGENCE SETTING UP ACROSS THE
LAKE...AS ALSO INDICATED BY LATEST SURFACE/MARINE OBS. LATEST
GUIDANCE IN GOOD AGREEMENT WITH CONDITIONS OVER THE LAKE TO
CONTINUE IMPROVING OVER THE NEXT SEVERAL HOURS. THIS COINCIDING
WITH A LONG FETCH OVER THE LAKE AND DECENT INVERSION
HEIGHTS...SHOULD ALLOW FOR CONTINUED DEVELOPMENT INTO THE EARLY
MORNING HOURS ON SATURDAY. SHORT RANGE GUIDANCE IS INDICATING THAT
THIS BAND WILL REMAIN SITUATED OVER THE LAKE/PORTER COUNTY LINE
BEFORE LOW LEVEL/BOUNDARY LAYER FLOW SHIFTS MORE EAST AND HELPS
STEER IT MORE OVER PORTER COUNTY BY THE EARLY MORNING HOURS. HAVE
INCREASE SNOW AMOUNTS ACROSS JASPER COUNTY AS LATEST RADAR RETURNS
HAVE BEEN REACHING THE NORTHERN PORTIONS OF THE COUNTY. WITH
CONDITIONS EXPECTED TO ONLY BECOME MORE FAVORABLE TONIGHT AND WITH
STRONG FLOW IN PLACE...PORTIONS OF JASPER COUNTY SHOULD SEE
WARNING CRITERIA SNOW. FORECASTED SNOW AMOUNTS CONTINUE TO BE IN
LINE WITH THE HIGHEST AMOUNTS STILL EXPECTED WITHIN PORTER
COUNTY...BEFORE THIS BAND SHIFTS EAST WITH TIME SATURDAY MORNING.
RODRIGUEZ
//PREV DISCUSSION...
355 PM CST
THE ONGOING SNOW EVENT WILL TRANSITION TO MORE OF A TRUE LAKE
EFFECT SNOW STORM INTO MAINLY NORTHWEST INDIANA THIS EVENING. THE
COMBINATION OF THE SNOW...GUSTY WINDS...AND FALLING TEMPERATURES
FREEZING SOME OF THE EARLIER MELTED SNOWFALL WILL CONTINUE TO
CREATE IMPACTS FOR A LARGE PART OF THE AREA INTO EARLY
EVENING...AND NORTHWEST INDIANA ALL NIGHT LONG.
LATE THIS AFTERNOON THROUGH SATURDAY
THE ARCTIC FRONT WILL CONTINUE TO MOVE SOUTHWARD...CLEARING THE
AREA BY EARLY EVENING. NORTHERLY WINDS GUSTING UP TO 35 MPH HAVE
USHERED IN A MUCH COLDER AIR ACROSS THE AREA WITH WIND CHILLS
HAVING DROPPED TO NEAR ZERO ALREADY ALONG THE WI STATE LINE. WATER
VAPOR SATELLITE SHOWS THE MAIN UPPER LEVEL WAVE MOVING OVER THE
AREA...WHICH COMBINED WITH THE STEEP LOW-LEVEL LAPSE RATES WILL
CONTINUE GENERAL SNOWFALL ACROSS THE IL AREA THROUGH EARLY TO MID
EVENING. SOME LAKE ENHANCEMENT IMMEDIATELY NEAR THE LAKE MICHIGAN
SHORE IS LIKELY.
A TRUE LAKE EFFECT BAND HAS ALREADY DEVELOPED JUST OFFSHORE BASED
ON KMKX/TORD RADAR SIGNATURES. THIS WILL CONTINUE TO BECOME
BETTER ESTABLISHED INTO COOK AND NORTHWEST LAKE COUNTIES THROUGH
EARLY EVENING BASED ON SHORT TERM GUIDANCE DEPICTION OF LOW-LEVEL
CONVERGENCE AND INSTABILITY. BY 9 PM AND AFTER...THE
EMPHASIS WILL BE SHIFTING INTO FAR SOUTHEAST COOK AND LAKE
COUNTIES WITH HIGH CONFIDENCE IN SHORT TERM MODELS. IT IS POSSIBLE
THE ADVISORY WILL NEED TO BE EXTENDED FOR COOK COUNTY AFTER 9
PM...AS SNOWFALL RATES WITHIN SUCH A BAND ARE LIKELY TO BE HEAVY
WITH EFFICIENT SNOW-TO-LIQUID RATIOS AND THE PRESENT INSTABILITY.
THE STRONG TEMPERATURE DIFFERENCE BETWEEN THE AIR MOVING OVER THE
LAKE AND THE 38 TO 43 DEGREE OPEN WATER LAKE TEMPERATURES ACROSS
THE SOUTHERN HALF WILL HELP TO GENERATE LAKE-INDUCED CAPE VALUES
TO 500 J/KG BY AFTER 9 PM...LASTING THROUGH THE OVERNIGHT AND
SHIFTING SLOWLY EAST. FAR SOUTHEAST COOK COUNTY COULD SEE TOTAL
SNOWFALL AMOUNTS APPROACH SIX INCHES.
THE CONVERGENT AXIS WILL ROTATE EAST FOCUSING INTO LAKE AND PORTER
COUNTIES OVERNIGHT. THE RATIOS SHOULD CONTINUE TO INCREASE...WITH
THE FAVORABLE SNOW GROWTH ZONE LOCATED BELOW THE EQUILIBRIUM
LEVEL. THE HIGHER WIND SPEEDS ARE LIKELY TO BREAK UP THE FLAKES
SOME...BUT THE HEAVY RATES SHOULD STILL COMPENSATE FOR THAT.
SIMULATED REFLECTIVITY ON SHORT TERM GUIDANCE ALSO RAMPS UP DURING
THAT TIME. THE TREND WITH ALMOST ALL HIGH RESOLUTION GUIDANCE WAS
TO SHIFT THIS EAST SLIGHTLY...REALLY FOCUSING INTO PORTER COUNTY
OVERNIGHT. THE HIGHEST SNOWFALL AMOUNTS TOWARD TEN INCHES IN OUR
FORECAST ARE FOCUSED IN EASTERN LAKE AND PORTER COUNTIES. THE
WIDTH OF THE BAND LOOKS TO NARROW AS IT SHIFTS EAST THOUGH...SO
AGAIN SOME UNCERTAINTY CONTINUES DUE TO THE LIKELY TIGHT GRADIENT
IN SNOWFALL. GIVEN THE LARGE VALUES OF LOW-LEVEL INSTABILITY
PRESENT...SEE NO REASON WHY SOME HIGHER AMOUNTS IN EXCESS OF TEN
INCHES TOWARDS 15 INCHES WOULD NOT BE OBSERVED IF THE BAND WERE
TO BE AS SLOW MOVING AFTER 9 PM AS FORECAST. WINDS GUSTING TO 40
MPH OR HIGHER ARE FAVORED BY OVERNIGHT IN NORTHWEST INDIANA DUE TO
THE LONG FRICTIONLESS FETCH OFF THE LAKE OF THE WIND COMPONENT AND
THE ENHANCED MIXING. THAT WILL AID IN NEAR WHITEOUT CONDITIONS AT
TIMES ACROSS NAMELY LAKE AND PORTER COUNTIES.
OVERALL NO CHANGES MADE TO THE GOING HEADLINES AT THIS TIME. THE
TIMING OF SNOW DEPARTURE IN PORTER COUNTY LOOKS TO BE BETWEEN 8 AM
AND NOON ON SATURDAY...SO THE TIMING OF ENDING THE HEADLINES LOOKS
GOOD. CLEARING TONIGHT HAS BEEN SLOWED IN THE FORECAST...BUT STILL
A STRONG DRY PUSH SHOULD LEAD TO MOST AREAS SEEING SUN BY
DAYBREAK SATURDAY.
MTF
SUNDAY THROUGH FRIDAY
PRIMARY CONCERN IS WHAT IS LOOKING TO BE A LONG DURATION LIGHT SNOW
EVENT ON MONDAY INTO EARLY TUESDAY. GENERALLY STAYED CLOSE TO BLEND
OF GUIDANCE AND PREVIOUS FORECAST THEREAFTER DUE TO LARGE MODEL
DIFFERENCES AND UNCERTAINTY.
SUNDAY THROUGH TUESDAY...
AFTER COLD START TO SUNDAY ON NORTHERN EDGE OF LARGE OF HIGH
PRESSURE...FULL SUN AND H85 TEMPERATURES WARMING TO -6 OR SO SHOULD
ALLOW RECOVERY TO 20S TO AROUND 30 DEGREES...WITH LOW 30S IN
DOWNTOWN CHICAGO. LIMITING FACTOR WILL BE NEW...DEEP SNOW COVER OVER
NORTHERN PORTIONS OF NW INDIANA...SO EXPECTING MID 20S THERE. IN
GENERAL...HIGH TEMPERATURES ARE CLOSE TO MOS GUIDANCE. ON SUNDAY
NIGHT...SHOULD BE UNDER RIDGE AXIS AND WITH CLEAR
SKIES AND DIMINISHED WINDS...TEMPERATURES WILL LIKELY FALL TO NEAR
OR BELOW NORMAL LEVELS DESPITE WARMING ALOFT. COLDEST TEMPERATURES
AGAIN EXPECTED FOR DEEP SNOW COVER AREA IN NORTHWEST INDIANA...WHERE
I WENT BELOW GUIDANCE AND FORECASTED LOW TEENS IN PORTER COUNTY.
CLOUDS WILL LIKELY INCREASE TOWARD DAYBREAK ACROSS NORTHWEST AND
NORTH CENTRAL ILLINOIS...SO TEMPERATURE DROP MAY SLOW OR STOP AFTER
INITIAL QUICK FALL AFTER DARK.
ON MONDAY...HIGH PRESSURE RIDGE WILL LOSE INFLUENCE OVER AREA AS WE
ENTER A PERSISTENT ISENTROPIC ASCENT/WARM ADVECTION
REGIME...ALLOWING INCREASE IN CLOUD COVER FIRST AND THEN
OVERSPREADING OF WIDESPREAD LIGHT PRECIPITATION. AFTER LATEST ECMWF
CAME IN A BIT SLOWER WITH PRECIP...SOME CONCERNS THAT POPS MAY HAVE
TO BE TRIMMED BACK/SLOWED SOME IN NORTHERN ILLINOIS MONDAY MONDAY MORNING
THROUGH NOON. NONETHELESS...AFOREMENTIONED ISENTROPIC ASCENT ALONG
WITH SOME MODEST MID AND UPPER LEVEL SUPPORT FROM MIDLEVEL TROUGH
PIVOTING THROUGH UPPER MIDWEST WILL BRING ENOUGH OMEGA THROUGH
SATURATED COLUMN FOR DECENT SNOW CRYSTAL GROWTH. COLD START TO DAY
PLUS H85 TEMPERATURES REMAINING AT -5C OR LESS THROUGH THE EVENT
WILL ENSURE PRECIP FALLS AS ALL SNOW. AFTERNOON TEMPS SHOULD TOP OUT
NEAR OR SLIGHTLY ABOVE 30F. BASED ON CURRENT PROGGED TRACK OF H5
TROUGH...BEST FORCING LOOKS LIKE IT WILL LINE UP CLOSER TO WISCONSIN
BORDER...BUT GOOD MODEL AGREEMENT LENT ENOUGH CONFIDENCE IN
WIDESPREAD PRECIP FOR ENTIRE CWA TO RAISE POPS TO LIKELY ACROSS THE
AREA INTO MONDAY NIGHT...TAPERING OFF OVERNIGHT INTO TUESDAY.
OVERALL...LOOKING LIKE A LIGHT QPF EVENT...PROBABLY STAYING BELOW
0.20" LE. THUS IN ALL LIKELIHOOD...IT WONT BE A BIG SNOW EVENT...BUT
POTENTIAL EXISTS FOR A COUPLE INCHES FOR AT LEAST A PORTION OF
CWA...WITH RATIOS SLIGHTLY ABOVE 10:1. HAVE LINGERING SLIGHT POPS ON
TUESDAY DUE TO UPPER TROUGH AXIS STAYING NEARBY...WITH TEMPERATURES
MODERATING A BIT MORE.
WEDNESDAY THROUGH FRIDAY...
POLAR VORTEX FULLY RETREATS INTO NORTHERN
CANADA...BRINGING US BACK TO A ZONAL...PACIFIC DOMINATED JET STREAM
PATTERN...ALLOWING TEMPERATURES TO WARM BACK ABOVE NORMAL LEVELS.
WARMING COULD BE LIMITED BY LINGERING SNOW COVER...BUT 40S ARE
CERTAINLY POSSIBLE DURING THE PERIOD...WITH H85 TEMPS WARMING TO AT
OR ABOVE 0C. AS MENTIONED...HOWEVER...LARGE MODEL DIFFERENCES AND
UNCERTAINTY ON MIDLEVEL AND SURFACE FEATURES...WITH ECMWF BRINGING
MIDLEVEL LOW AND SURFACE REFLECTION ACROSS AREA WEDNESDAY INTO
THURSDAY...WHILE GFS HAS A DRY LOOK TO IT. HAVE SLIGHT TO LOW END
CHANCE POPS FROM ALL BLEND DURING THIS PERIOD AND A RAIN OR SNOW
MENTION DUE TO MARGINAL AT BEST THERMAL PROFILE.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* NORTH-NORTHWEST WINDS GUSTING 25-30 KT THROUGH MUCH OF THE NIGHT
WHILE POSSIBLY EASING TO 20-25 KT IN THE MORNING.
MDB
//DISCUSSION...UPDATED 06Z...
VERY WELL ORGANIZED NORTH-SOUTH LAKE EFFECT SNOW BAND CONTINUES TO
BRING VERY HEAVY SNOW IN THE NORTHWEST INDIANA. GYY REMAINS JUST
TO THE WEST OF THE BAND WITH PERIODS OF LIGHT SNOW BUT THE BAND
DOES CONTINUE TO WOBBLE EAST AND WEST SLIGHTLY KEEPING THE
POTNEITAL FOR SHORT PERIODS OF MORE INTENSE SNOWFALL TO THE
TERMINAL OF THE SEVERAL HOURS. THE BAND WILL LIKELY BEGIN TO SHIFT
MORE TO THE EAST OVERNIGHT ALLOWING SNOW TO END AT GYY...BUT IT IS
NOT CLEAR WHEN EXACTLY THIS WILL OCCUR. NORTHWEST WINDS GUSTING
ANYWHERE FROM 30 TO NEAR 40 KT AT TIMES WILL CAUSE BLOWING AND
DRIFTING AND KEEP VSBY LIMITED EVEN WHEN SNOW IS NOT FALLING.
ELSEHWERE...VFR HAS SPREAD ACROSS THE NORTHERN ILLINOIS TERMINALS
AND WILL CONTINUE OVERNIGHT. NORTH-NORTHWEST WINDS CONTINUE TO
GUST INTO THE 25-30 KT RANGE AT THE CHI METRO TERMINALS THANKS TO
TIGHT PRESSURE GRADIENT CLOSER TO THE LAKE. SPEEDS MAY EASE OFF A
BIT BUT LIKELY REMAIN GUSTY SATURDAY MORNING WHILE TURNING A BIT
MORE WESTERLY. GUSTS TO AROUND 25 KT ARE EXPECTED DURING THE
AFTERNOON. VFR CONDITIONS EXPECTED TO PREVAIL WITH AN UPPER LEVEL
WAVE BRINGING SOME MID CLOUD COVER AT TIMES DURING THE DAY. THE
VERY DRY LOW LEVELS SHOULD PRECLUDE ANY STRATO CU DEVELOPMENT. WINDS
WILL EASE SOMEWHAT SATURDAY EVENING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN NORTH-NORTHWEST WINDS GUSTING 25-30 KT
THROUGH MUCH OF THE NIGHT BUT LOW-MEDIUM CONFIDENCE IN GUST
SPEEDS SATURDAY MORNING AND AFTERNOON.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...VFR.
MONDAY/TUESDAY...LIGHT SNOW LIKELY WITH IFR POSSIBLE.
WEDNESDAY...VFR.
THURSDAY...CHANCE OF RAIN AND SNOW.
MDB
&&
.MARINE...
156 PM CST
THE MAIN CONCERNS CONTINUE TO FOCUS ON THE STRONG WINDS ACROSS LAKE
MICHIGAN TONIGHT INTO SATURDAY. THE STRONG SURFACE COLD FRONT IS
MOVING ACROSS THE SOUTHERN TIP OF LAKE MICHIGAN EARLY THIS
AFTERNOON. I EXPECT NORTHERLY GALE FORCE WINDS AROUND 35 KNOTS IN
THE WAKE OF THIS FRONT. AS VERY COLD AIR CONTINUES TO SPILL OVER THE
LAKE THIS EVENING...A FAVORABLE THERMODYNAMIC SETUP WILL OCCUR FOR A
BANDS OF INTENSE LAKE EFFECT SNOW TO DEVELOP. THERE IS ALSO A GOOD
POSSIBILITY THAT AS SOME AREAS ACROSS THE SOUTHERN END OF THE LAKE
MAY SEE GALES INCREASE TO 40 KT FOR A PERIOD TONIGHT AS THESE
CONVERGENT BANDS OF SNOW DEVELOP. THESE STRONG WINDS WILL LIKELY
ALSO AFFECT THE INDIANA NEAR SHORE WATERS.
WINDS WILL ABATE SOME ON SATURDAY. HOWEVER...THE PRESSURE GRADIENT
WILL REMAIN FAIRLY TIGHT ACROSS THE LAKE AS HIGH PRESSURE DROPS OUT
OF SOUTHERN CANADA AND BUILDS ACROSS THE LOWER AND MIDDLE MISSOURI
RIVER VALLEY. THEREFORE...EXPECT NORTHWEST WINDS TO 30 KT TO
CONTINUE ON SATURDAY AND SATURDAY NIGHT. THIS SURFACE HIGH WILL
BUILD EASTWARD ACROSS THE OHIO VALLEY ON SUNDAY AND SUNDAY NIGHT.
ONCE THIS OCCURS THE WINDS WILL BECOME WEST SOUTHWESTERLY BY MONDAY.
WIND SPEEDS WILL DIMINISH INTO MONDAY.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW WARNING...INZ001 UNTIL 4 AM SATURDAY.
LAKE EFFECT SNOW WARNING...INZ002-INZ011 UNTIL 9 AM SATURDAY.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 AM
SATURDAY.
GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 UNTIL 6
AM SATURDAY.
GALE WARNING...ILLINOIS NEARSHORE WATERS UNTIL 4 AM SATURDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...4 AM SATURDAY TO 6
AM SUNDAY.
GALE WARNING...INDIANA NEARSHORE WATERS UNTIL 10 AM SATURDAY.
SMALL CRAFT ADVISORY...LMZ743-LMZ744-LMZ745...10 AM SATURDAY TO
2 PM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1009 PM CST FRI FEB 10 2012
.DISCUSSION...
1008 PM CST
REMAINING ADVISORIES HAVE BEEN ALLOWED TO EXPIRE THIS
EVENING...HAVE CONTINUED LAKE EFFECT WARNING FOR LAKE AND PORTER
IN INDIANA...AND HAVE UPGRADED JASPER COUNTY TO A LAKE EFFECT
WARNING.
LATEST RADAR ANALYSIS CONTINUES TO SHOW LAKE EFFECT SNOW SHOWERS
DEVELOPING BUT PRIMARILY REMAINING IN INDIANA...WITH THE MORE
SYNOPTICALLY DRIVEN SNOW HAVING SINCE DIMINISHED OVER THE LAST
COUPLE OF THE HOURS. LATEST TRENDS IN LINE WITH CURRENT HEADLINES
IN PLACE WITH LAKE EFFECT SNOW SHOWERS CONTINUING OVERNIGHT. OVER
THE LAST COUPLE OF HOURS...A STRONGER AND MORE DEFINED SNOW BAND
HAS DEVELOPED AND SITUATED ITSELF OVER LAKE AND PORTER COUNTIES IN
INDIANA. LATEST RUC ANALYSIS SHOWING CONDITIONS OVER THE LAKE HAVE
IMPROVED SIGNIFICANTLY IN REGARDS TO SNOW POTENTIAL WITH 850 DELTA
TS IN UPWARDS OF 18C AND STRONG CONVERGENCE SETTING UP ACROSS THE
LAKE...AS ALSO INDICATED BY LATEST SURFACE/MARINE OBS. LATEST
GUIDANCE IN GOOD AGREEMENT WITH CONDITIONS OVER THE LAKE TO
CONTINUE IMPROVING OVER THE NEXT SEVERAL HOURS. THIS COINCIDING
WITH A LONG FETCH OVER THE LAKE AND DECENT INVERSION
HEIGHTS...SHOULD ALLOW FOR CONTINUED DEVELOPMENT INTO THE EARLY
MORNING HOURS ON SATURDAY. SHORT RANGE GUIDANCE IS INDICATING THAT
THIS BAND WILL REMAIN SITUATED OVER THE LAKE/PORTER COUNTY LINE
BEFORE LOW LEVEL/BOUNDARY LAYER FLOW SHIFTS MORE EAST AND HELPS
STEER IT MORE OVER PORTER COUNTY BY THE EARLY MORNING HOURS. HAVE
INCREASE SNOW AMOUNTS ACROSS JASPER COUNTY AS LATEST RADAR RETURNS
HAVE BEEN REACHING THE NORTHERN PORTIONS OF THE COUNTY. WITH
CONDITIONS EXPECTED TO ONLY BECOME MORE FAVORABLE TONIGHT AND WITH
STRONG FLOW IN PLACE...PORTIONS OF JASPER COUNTY SHOULD SEE
WARNING CRITERIA SNOW. FORECASTED SNOW AMOUNTS CONTINUE TO BE IN
LINE WITH THE HIGHEST AMOUNTS STILL EXPECTED WITHIN PORTER
COUNTY...BEFORE THIS BAND SHIFTS EAST WITH TIME SATURDAY MORNING.
RODRIGUEZ
&&
.PREV DISCUSSION...
355 PM CST
THE ONGOING SNOW EVENT WILL TRANSITION TO MORE OF A TRUE LAKE
EFFECT SNOW STORM INTO MAINLY NORTHWEST INDIANA THIS EVENING. THE
COMBINATION OF THE SNOW...GUSTY WINDS...AND FALLING TEMPERATURES
FREEZING SOME OF THE EARLIER MELTED SNOWFALL WILL CONTINUE TO
CREATE IMPACTS FOR A LARGE PART OF THE AREA INTO EARLY
EVENING...AND NORTHWEST INDIANA ALL NIGHT LONG.
LATE THIS AFTERNOON THROUGH SATURDAY
THE ARCTIC FRONT WILL CONTINUE TO MOVE SOUTHWARD...CLEARING THE
AREA BY EARLY EVENING. NORTHERLY WINDS GUSTING UP TO 35 MPH HAVE
USHERED IN A MUCH COLDER AIR ACROSS THE AREA WITH WIND CHILLS
HAVING DROPPED TO NEAR ZERO ALREADY ALONG THE WI STATE LINE. WATER
VAPOR SATELLITE SHOWS THE MAIN UPPER LEVEL WAVE MOVING OVER THE
AREA...WHICH COMBINED WITH THE STEEP LOW-LEVEL LAPSE RATES WILL
CONTINUE GENERAL SNOWFALL ACROSS THE IL AREA THROUGH EARLY TO MID
EVENING. SOME LAKE ENHANCEMENT IMMEDIATELY NEAR THE LAKE MICHIGAN
SHORE IS LIKELY.
A TRUE LAKE EFFECT BAND HAS ALREADY DEVELOPED JUST OFFSHORE BASED
ON KMKX/TORD RADAR SIGNATURES. THIS WILL CONTINUE TO BECOME
BETTER ESTABLISHED INTO COOK AND NORTHWEST LAKE COUNTIES THROUGH
EARLY EVENING BASED ON SHORT TERM GUIDANCE DEPICTION OF LOW-LEVEL
CONVERGENCE AND INSTABILITY. BY 9 PM AND AFTER...THE
EMPHASIS WILL BE SHIFTING INTO FAR SOUTHEAST COOK AND LAKE
COUNTIES WITH HIGH CONFIDENCE IN SHORT TERM MODELS. IT IS POSSIBLE
THE ADVISORY WILL NEED TO BE EXTENDED FOR COOK COUNTY AFTER 9
PM...AS SNOWFALL RATES WITHIN SUCH A BAND ARE LIKELY TO BE HEAVY
WITH EFFICIENT SNOW-TO-LIQUID RATIOS AND THE PRESENT INSTABILITY.
THE STRONG TEMPERATURE DIFFERENCE BETWEEN THE AIR MOVING OVER THE
LAKE AND THE 38 TO 43 DEGREE OPEN WATER LAKE TEMPERATURES ACROSS
THE SOUTHERN HALF WILL HELP TO GENERATE LAKE-INDUCED CAPE VALUES
TO 500 J/KG BY AFTER 9 PM...LASTING THROUGH THE OVERNIGHT AND
SHIFTING SLOWLY EAST. FAR SOUTHEAST COOK COUNTY COULD SEE TOTAL
SNOWFALL AMOUNTS APPROACH SIX INCHES.
THE CONVERGENT AXIS WILL ROTATE EAST FOCUSING INTO LAKE AND PORTER
COUNTIES OVERNIGHT. THE RATIOS SHOULD CONTINUE TO INCREASE...WITH
THE FAVORABLE SNOW GROWTH ZONE LOCATED BELOW THE EQUILIBRIUM
LEVEL. THE HIGHER WIND SPEEDS ARE LIKELY TO BREAK UP THE FLAKES
SOME...BUT THE HEAVY RATES SHOULD STILL COMPENSATE FOR THAT.
SIMULATED REFLECTIVITY ON SHORT TERM GUIDANCE ALSO RAMPS UP DURING
THAT TIME. THE TREND WITH ALMOST ALL HIGH RESOLUTION GUIDANCE WAS
TO SHIFT THIS EAST SLIGHTLY...REALLY FOCUSING INTO PORTER COUNTY
OVERNIGHT. THE HIGHEST SNOWFALL AMOUNTS TOWARD TEN INCHES IN OUR
FORECAST ARE FOCUSED IN EASTERN LAKE AND PORTER COUNTIES. THE
WIDTH OF THE BAND LOOKS TO NARROW AS IT SHIFTS EAST THOUGH...SO
AGAIN SOME UNCERTAINTY CONTINUES DUE TO THE LIKELY TIGHT GRADIENT
IN SNOWFALL. GIVEN THE LARGE VALUES OF LOW-LEVEL INSTABILITY
PRESENT...SEE NO REASON WHY SOME HIGHER AMOUNTS IN EXCESS OF TEN
INCHES TOWARDS 15 INCHES WOULD NOT BE OBSERVED IF THE BAND WERE
TO BE AS SLOW MOVING AFTER 9 PM AS FORECAST. WINDS GUSTING TO 40
MPH OR HIGHER ARE FAVORED BY OVERNIGHT IN NORTHWEST INDIANA DUE TO
THE LONG FRICTIONLESS FETCH OFF THE LAKE OF THE WIND COMPONENT AND
THE ENHANCED MIXING. THAT WILL AID IN NEAR WHITEOUT CONDITIONS AT
TIMES ACROSS NAMELY LAKE AND PORTER COUNTIES.
OVERALL NO CHANGES MADE TO THE GOING HEADLINES AT THIS TIME. THE
TIMING OF SNOW DEPARTURE IN PORTER COUNTY LOOKS TO BE BETWEEN 8 AM
AND NOON ON SATURDAY...SO THE TIMING OF ENDING THE HEADLINES LOOKS
GOOD. CLEARING TONIGHT HAS BEEN SLOWED IN THE FORECAST...BUT STILL
A STRONG DRY PUSH SHOULD LEAD TO MOST AREAS SEEING SUN BY
DAYBREAK SATURDAY.
MTF
SUNDAY THROUGH FRIDAY
PRIMARY CONCERN IS WHAT IS LOOKING TO BE A LONG DURATION LIGHT SNOW
EVENT ON MONDAY INTO EARLY TUESDAY. GENERALLY STAYED CLOSE TO BLEND
OF GUIDANCE AND PREVIOUS FORECAST THEREAFTER DUE TO LARGE MODEL
DIFFERENCES AND UNCERTAINTY.
SUNDAY THROUGH TUESDAY...
AFTER COLD START TO SUNDAY ON NORTHERN EDGE OF LARGE OF HIGH
PRESSURE...FULL SUN AND H85 TEMPERATURES WARMING TO -6 OR SO SHOULD
ALLOW RECOVERY TO 20S TO AROUND 30 DEGREES...WITH LOW 30S IN
DOWNTOWN CHICAGO. LIMITING FACTOR WILL BE NEW...DEEP SNOW COVER OVER
NORTHERN PORTIONS OF NW INDIANA...SO EXPECTING MID 20S THERE. IN
GENERAL...HIGH TEMPERATURES ARE CLOSE TO MOS GUIDANCE. ON SUNDAY
NIGHT...SHOULD BE UNDER RIDGE AXIS AND WITH CLEAR
SKIES AND DIMINISHED WINDS...TEMPERATURES WILL LIKELY FALL TO NEAR
OR BELOW NORMAL LEVELS DESPITE WARMING ALOFT. COLDEST TEMPERATURES
AGAIN EXPECTED FOR DEEP SNOW COVER AREA IN NORTHWEST INDIANA...WHERE
I WENT BELOW GUIDANCE AND FORECASTED LOW TEENS IN PORTER COUNTY.
CLOUDS WILL LIKELY INCREASE TOWARD DAYBREAK ACROSS NORTHWEST AND
NORTH CENTRAL ILLINOIS...SO TEMPERATURE DROP MAY SLOW OR STOP AFTER
INITIAL QUICK FALL AFTER DARK.
ON MONDAY...HIGH PRESSURE RIDGE WILL LOSE INFLUENCE OVER AREA AS WE
ENTER A PERSISTENT ISENTROPIC ASCENT/WARM ADVECTION
REGIME...ALLOWING INCREASE IN CLOUD COVER FIRST AND THEN
OVERSPREADING OF WIDESPREAD LIGHT PRECIPITATION. AFTER LATEST ECMWF
CAME IN A BIT SLOWER WITH PRECIP...SOME CONCERNS THAT POPS MAY HAVE
TO BE TRIMMED BACK/SLOWED SOME IN NORTHERN ILLINOIS MONDAY MONDAY MORNING
THROUGH NOON. NONETHELESS...AFOREMENTIONED ISENTROPIC ASCENT ALONG
WITH SOME MODEST MID AND UPPER LEVEL SUPPORT FROM MIDLEVEL TROUGH
PIVOTING THROUGH UPPER MIDWEST WILL BRING ENOUGH OMEGA THROUGH
SATURATED COLUMN FOR DECENT SNOW CRYSTAL GROWTH. COLD START TO DAY
PLUS H85 TEMPERATURES REMAINING AT -5C OR LESS THROUGH THE EVENT
WILL ENSURE PRECIP FALLS AS ALL SNOW. AFTERNOON TEMPS SHOULD TOP OUT
NEAR OR SLIGHTLY ABOVE 30F. BASED ON CURRENT PROGGED TRACK OF H5
TROUGH...BEST FORCING LOOKS LIKE IT WILL LINE UP CLOSER TO WISCONSIN
BORDER...BUT GOOD MODEL AGREEMENT LENT ENOUGH CONFIDENCE IN
WIDESPREAD PRECIP FOR ENTIRE CWA TO RAISE POPS TO LIKELY ACROSS THE
AREA INTO MONDAY NIGHT...TAPERING OFF OVERNIGHT INTO TUESDAY.
OVERALL...LOOKING LIKE A LIGHT QPF EVENT...PROBABLY STAYING BELOW
0.20" LE. THUS IN ALL LIKELIHOOD...IT WONT BE A BIG SNOW EVENT...BUT
POTENTIAL EXISTS FOR A COUPLE INCHES FOR AT LEAST A PORTION OF
CWA...WITH RATIOS SLIGHTLY ABOVE 10:1. HAVE LINGERING SLIGHT POPS ON
TUESDAY DUE TO UPPER TROUGH AXIS STAYING NEARBY...WITH TEMPERATURES
MODERATING A BIT MORE.
WEDNESDAY THROUGH FRIDAY...
POLAR VORTEX FULLY RETREATS INTO NORTHERN
CANADA...BRINGING US BACK TO A ZONAL...PACIFIC DOMINATED JET STREAM
PATTERN...ALLOWING TEMPERATURES TO WARM BACK ABOVE NORMAL LEVELS.
WARMING COULD BE LIMITED BY LINGERING SNOW COVER...BUT 40S ARE
CERTAINLY POSSIBLE DURING THE PERIOD...WITH H85 TEMPS WARMING TO AT
OR ABOVE 0C. AS MENTIONED...HOWEVER...LARGE MODEL DIFFERENCES AND
UNCERTAINTY ON MIDLEVEL AND SURFACE FEATURES...WITH ECMWF BRINGING
MIDLEVEL LOW AND SURFACE REFLECTION ACROSS AREA WEDNESDAY INTO
THURSDAY...WHILE GFS HAS A DRY LOOK TO IT. HAVE SLIGHT TO LOW END
CHANCE POPS FROM ALL BLEND DURING THIS PERIOD AND A RAIN OR SNOW
MENTION DUE TO MARGINAL AT BEST THERMAL PROFILE.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* NORTH-NORTHWEST WINDS GUSTING TO 25-30 KT THROUGH THE EVENING
THEN EASING TO AROUND 25 KT OVERNIGHT.
* STRONG LAKE EFFECT SNOW BAND REMAINING JUST OFF SHORE OF
ILLINOIS THROUGH THE EVENING THEN SHIFTING EASTWARD OVERNIGHT.
MDB
//DISCUSSION...UPDATED 03Z...
LAKE EFFECT SNOW BAND BECOMING BETTER ORGANIZED AND MORE INTENSE.
BAND EXPECTED TO WOBBLE BACK AND FORTH FROM EAST TO WEST FOR A FEW
HOURS BEFORE MAKING A STEADIER MOVE TO THE EAST. LATEST RADAR
TRENDS SUPPORT GYY SEEING A PERIOD OF HEAVIER SNOW FOR PERHAPS A
FEW HOURS WITH VERY INTENSE SNOWFALL RATES. THE BULK OF THE BAND
WILL LIKELY REMAIN JUST TO THE EAST. ONCE THE HEAVIEST SNOW EXITS
LATER THIS EVENING SNOW SHOWERS WILL PROBABLY CONTINUE BUT VSBY
WILL LIKELY BE IMPROVED TO A FEW MILES...BUT ADDITIONAL BURSTS OF
SNOW MAY REMAIN POSSIBLE A FEW HOURS BEYOND MIDNIGHT. STRONG
NORTH-NORTHWEST WINDS WILL CONTINUE TO GUST TO AROUND 35 KT WITH
PERIODIC GUSTS CLOSER TO 40 KT NOT OUT OF THE QUESTION. THIS WILL
YIELD BLOWING SNOW AND REDUCED VSBY EVEN IF FALLING SNOW IS LESS
INTENSE.
ELSEWHERE...SKIES ARE QUICKLY CLEARING ACROSS NORTHERN ILLINOIS
WITH MAINLY SKC EXPECTED ACROSS THE WESTERN CHI METRO AND POINTS
WEST WITH SOME LOWER END VFR CLOUDS LINGERING CLOSER TO THE
LAKESHORE/ORD/MDW THROUGH THE EVENING. NORTH-NORTHWEST WINDS WILL
CONTINUE TO GUST IN THE 25-30 KT RANGE ACROSS THE CHI METRO
TERMINALS WITH LESSER GUSTS TO THE WEST.
FROM 00Z...
LAST OF THE LARGE SCALE SNOW IS MOVING SOUTHEAST ACROSS
ORD/MDW AT 00Z WHILE LAKE EFFECT BAND CONTINUES TO IMPACT GYY AND
VICINITY. SOME LIGHT SNOW SHOWERS OR FLURRIES MAY TRAIL THE MAIN
AREA OF SNOW AT RFD/DPA/ORD INTO MID EVENING. MDW IS A BIT TOUGHER
WITH THE BULK OF THE SNOW EXITING OVER THE NEXT HOUR OR SO BUT
WITH THE PROXIMITY OF THE FLOW FROM THE LAKE ADDITIONAL SNOW
SHOWERS MAY CONTINUE THROUGH MID EVENING. WILL CONTINUE WITH LIGHT
SNOW AND SOME REDUCED VSBY THERE FOR NOW.
GYY...THE LAKE BAND IS EXPECTED TO BECOME BETTER ORGANIZED INTO
MID EVENING LIKELY CONTINUING TO AFFECT GYY INTO THE OVERNIGHT
BEFORE SHIFTING EAST. STRONG NORTH WINDS GUSTING IN THE 35-45 KT
RANGE WILL CONTINUE AT GYY LEADING TO SIGNIFICANT BLOWING AND
DRIFTING SNOW. EXTREME SNOWFALL RATES OF 1-3 INCHES PER HOUR ARE
EXPECTED WITH THE SNOW BAND ONCE IT BECOMES BETTER ORGANIZED THIS
EVENING. THE MAIN CHALLENGE WILL BE TRACKING HOW LONG THE BAND
WILL AFFECT THE TERMINAL WHICH AT THIS POINT LOOKS TO BE THROUGH
MOST OF THE EVENING AND POSSIBLY INTO THE EARLY OVERNIGHT HOURS.
ONCE THE BAND MOVES OFF TO THE EAST SNOW WILL QUICKLY LET UP BUT
BLOWING SNOW WILL LIKELY CONTINUE RESULTING IN CONTINUED REDUCED
VISIBILITY.
THE ILLINOIS TERMINALS WILL LIKELY SCATTER OUT OVERNIGHT BUT SPECIFIC
TIMING IS A BIT UNCERTAIN. NORTH-NORTHWEST WINDS WILL TURN MORE
NORTHWEST SATURDAY MORNING BUT REMAIN GUSTY INTO THE 20-25 KT
THROUGH MUCH OF THE DAY. VFR CONDITIONS ARE EXPECTED FOR SATURDAY
WITH LOWER END VFR CIGS POSSIBLY IN THE MORNING BUT CLEARING FOR
THE AFTERNOON.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE IN WIND FORECAST.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...VFR.
MONDAY/TUESDAY...LIGHT SNOW LIKELY WITH IFR POSSIBLE.
WEDNESDAY...VFR.
THURSDAY...CHANCE OF RAIN AND SNOW.
MDB
&&
.MARINE...
156 PM CST
THE MAIN CONCERNS CONTINUE TO FOCUS ON THE STRONG WINDS ACROSS LAKE
MICHIGAN TONIGHT INTO SATURDAY. THE STRONG SURFACE COLD FRONT IS
MOVING ACROSS THE SOUTHERN TIP OF LAKE MICHIGAN EARLY THIS
AFTERNOON. I EXPECT NORTHERLY GALE FORCE WINDS AROUND 35 KNOTS IN
THE WAKE OF THIS FRONT. AS VERY COLD AIR CONTINUES TO SPILL OVER THE
LAKE THIS EVENING...A FAVORABLE THERMODYNAMIC SETUP WILL OCCUR FOR A
BANDS OF INTENSE LAKE EFFECT SNOW TO DEVELOP. THERE IS ALSO A GOOD
POSSIBILITY THAT AS SOME AREAS ACROSS THE SOUTHERN END OF THE LAKE
MAY SEE GALES INCREASE TO 40 KT FOR A PERIOD TONIGHT AS THESE
CONVERGENT BANDS OF SNOW DEVELOP. THESE STRONG WINDS WILL LIKELY
ALSO AFFECT THE INDIANA NEAR SHORE WATERS.
WINDS WILL ABATE SOME ON SATURDAY. HOWEVER...THE PRESSURE GRADIENT
WILL REMAIN FAIRLY TIGHT ACROSS THE LAKE AS HIGH PRESSURE DROPS OUT
OF SOUTHERN CANADA AND BUILDS ACROSS THE LOWER AND MIDDLE MISSOURI
RIVER VALLEY. THEREFORE...EXPECT NORTHWEST WINDS TO 30 KT TO
CONTINUE ON SATURDAY AND SATURDAY NIGHT. THIS SURFACE HIGH WILL
BUILD EASTWARD ACROSS THE OHIO VALLEY ON SUNDAY AND SUNDAY NIGHT.
ONCE THIS OCCURS THE WINDS WILL BECOME WEST SOUTHWESTERLY BY MONDAY.
WIND SPEEDS WILL DIMINISH INTO MONDAY.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW WARNING...INZ001 UNTIL 4 AM SATURDAY.
LAKE EFFECT SNOW WARNING...INZ002-INZ011 UNTIL 9 AM SATURDAY.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 AM
SATURDAY.
GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 UNTIL 6
AM SATURDAY.
GALE WARNING...ILLINOIS NEARSHORE WATERS UNTIL 4 AM SATURDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...4 AM SATURDAY TO 6
AM SUNDAY.
GALE WARNING...INDIANA NEARSHORE WATERS UNTIL 10 AM SATURDAY.
SMALL CRAFT ADVISORY...LMZ743-LMZ744-LMZ745...10 AM SATURDAY TO
2 PM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
112 PM EST SAT FEB 11 2012
.AVIATION /18 UTC TAFS/...
LES EVENT BEGINNING TO WANE AS UPSTREAM WITHIN CLOUD SHEAR INCRS.
OVERALL STEERING FLOW CONTS TO BACK DRAWING MUCH DRIER AIR INTO
SYSTEM...SQUELCHING VERTICAL EXTENT OF CONVECTION. KSBN SHOULD BE
IN FINAL HOURS OF LIFR POTNL AT KSBN BEFORE MUCH IMPROVED CONDS
BYND 20 UTC. STRONG WINDS AND MORE CELLULAR SHSN COULD STILL LEAD
TO HIGHLY VARIABLE VSBYS THEREAFTER INTO THE EVENING HOURS BEFORE
ENDING. FURTHER INLAND AT KFWA SERN TERMINUS OF LES BANDS SHOULD
SKIRT IN/OUT OF VCNTY INTO MID AFTN...THOUGH OVERALL IMPACT QUITE
MARGINAL/BRIEF AND KEPT TEMPO GROUP ABOVE FUEL ALT REQRMNTS.
CLEARING SKIES AND WINDS RELAX AS SUBSIDENCE INVERSION
STRENGTHENS.
&&
.PREV DISCUSSION... /ISSUED 423 AM EST SAT FEB 11 2012/
SHORT TERM.../TODAY THROUGH SUNDAY NIGHT/
..LAKE EFFECT SNOW EVENT UNDERWAY...
ARCTIC COLD FRONT HAS SWEPT ACROSS THE FORECAST AREA WITH
TEMPERATURES IN THE TEENS AND DEWPTS FALLING INTO THE SINGLE DIGITS.
SOME LEFTOVER LIGHT SNOW WAS SEEN ON OBS AND RADAR ACROSS PORTIONS
OF NORTHEASTERN INDIANA AND NORTHWESTERN OHIO. MAIN FOCUS WAS WELL
DEFINED INTENSE LAKE EFFECT SNOW BAND THAT RAPIDLY DEVELOPED ACROSS
LAKE AND PORTER COUNTIES THIS PAST EVENING AND AFTER A BRIEF SHIFT
WEST AND INCREASE IN EASTERN PROGRESS HAS BEEN NOTED WITH THE BAND
CURRENTLY SITUATED ACROSS LAPORTE AND STARKE COUNTIES AHEAD OF
SCHEDULE. REPORT FROM VALPO UNIV OF LIGHTNING WAS RECEIVED AS THE
HEAVIEST PART OF THE BAND SHIFTED ACROSS THAT AREA. RADAR TRENDS
ACROSS THE FORECAST AREA HAS SHOWN A DOWNWARD TREND IN SOUTHERN
EXTENT AND INTENSITY OF THE BAND. UPSTREAM ACROSS THE LAKE KGRR
RADAR SHOWING AN INCREASE IN RETURNS AS THE BAND SHIFTED MORE ALONG
THE EASTERN SHORE OF THE LAKE. A FEW RUNS OF THE HRRR SUGGESTED THIS
MAY OCCUR WITH THE INITIAL BAND WEAKENING WITH TIME AS CONVERGENCE
WEAKENED AND MORE OF A MULTI BAND SETUP BEGAN TO ESTABLISH WITH TIME
THIS MORNING. WHILE FULL WARNING CRITERIA MAY NOT BE
MET...DETERIORATING CONDITIONS STILL WARRANT HOLDING ONTO CURRENT
HEADLINES. RISK FOR WARNING CRITERIA STILL POSSIBLE OVER BERRIEN
COUNTY AS BAND REORIENTS AND PERSISTS INTO EARLY AFTERNOON. DID
EXPAND POPS FURTHER SOUTH AND EAST AS INLAND EXTENT OF BANDS MAY
INCREASE AS OVERALL FLOW INCREASES SOMEWHAT WITH STRONGER GRADIENT
SHIFTING ACROSS THE AREA. WOULD NOT EXPECT MUCH IMPACT BUT FELT AT
LEAST CHC POPS WERE NEEDED DOWNSTREAM OF THE BAND.
GIVEN UNCERTAINTY OF EXTENT AND INTENSITY OF HEAVIEST BANDS HAVE
WENT WITH LIKELY POPS INTO THE AFTERNOON WITH ONLY LIGHT ADDITIONAL
ACCUMS.
NW FLOW WILL PERSIST ACROSS THE REGION INTO SUNDAY. HOWEVER...LL
TEMPS WILL QUICKLY UNDERGO MODERATION TONIGHT INTO SUNDAY CAUSING
DELTA T`S TO DECREASE AND INVERSION HGTS TO LOWER. THE RESULT WILL
BE SOME LINGERING VERY LIGHT SNOW OR FLURRIES INTO TONIGHT BEFORE
ENDING. SUNDAY/SUNDAY NIGHT APPEAR DRY AT THIS POINT WITH HIGH
PRESSURE BUILDING IN. MEAN RH VALUES DROPS CONSIDERABLY BY SUNDAY
AFTERNOON INTO SUNDAY NIGHT...ALLOWING FOR MOSTLY CLEAR TO CLEAR
SKIES AND MODERATING TEMPS.
LONG TERM...MONDAY THROUGH FRIDAY
OVERALL VERY FEW CHANGES REQUIRED TO THE LONG TERM PERIOD FOR THIS
FORECAST CYCLE.
FOR MONDAY...LOW LEVEL ANTICYCLONE WILL SHIFT EASTWARD THROUGH THE
LOWER MS RIVER VALLEY INTO THE SOUTHEAST US...EVENTUALLY ALLOWING
LOW LEVEL RETURN SOUTHWESTERLY FLOW TO SETUP. A SHEARED UPPER VORT
MAX DIVORCED FROM STRONGER STEERING FLOW AS A RESULT OF WESTERN
CONUS SPLIT FLOW SHOULD GRADUALLY GET PHASED WITH A MORE AMPLIFIED
SOUTHERN STREAM TROUGH KICKING OUT OF THE FOUR CORNERS REGION. AS
THIS OCCURS...STRONGER LOW LEVEL THETAE ADVECTION/ISENTROPIC LIFT
SHOULD BE FOCUSED JUST WEST OF THE AREA. NAM/GFS ISENTROPIC PROGS IN
290-280K LAYER DO INDICATE MORE SUBSTANTIAL LOWERING OF
CONDENSATIONAL PRESSURE DEFICITS THROUGHOUT THIS LAYER BY LATE IN
THE DAY MONDAY...BUT SUBCLOUD LAYER MAY BE TOO DRY FOR MOST AREAS TO
RECEIVE ANY PRECIP MONDAY AFTERNOON. A SHARP LOW LEVEL GRADIENT
NOTED IN MIXING RATIOS THROUGHOUT THIS LAYER FROM WEST TO EAST ON
MONDAY...AND PREVIOUS POP GRADIENT MONDAY AFTERNOON FROM LOW CHANCE
WEST TO SLIGHT CHANCE EAST STILL APPEARS REASONABLE. STRONGER
ISENTROPIC UPGLIDE AND MID LEVEL FORCING TO MOVE IN FOR MONDAY NIGHT
WHICH STILL APPEARS TO BE SHAPING UP AS A HIGH POP/LOW QPF EVENT
BASED ON A RELATIVELY SHORT DURATION OF BETTER LOW/MID LEVEL
MOISTURE PROFILES AND RATHER DISJOINTED NATURE OF MID/UPPER LEVEL
FORCING WITH ONLY PARTIAL PHASING OF THESE AFOREMENTIONED SHORT
WAVES. MOST OF PRECIP EXPECTED MONDAY NIGHT BUT WILL CONTINUE TO
CARRY CHANCE -SN MENTION INTO TUESDAY WITH LAGGING SHORT WAVE SLOW
TO EXIT THE AREA. PRECIP MAY END AS A PERIOD OF DRIZZLE/FLURRIES
TUESDAY NIGHT...ESPECIALLY ACROSS EASTERN AREAS...AS MOISTURE
PROFILES BECOMING INCREASING SHALLOW WITH ONLY WEAK MID LEVEL
FORCING.
MEDIUM RANGE MODELS HAVE STARTED TO CONVERGE A BIT MORE IN REGARDS
TO MID/LATE WEEK SYSTEM WITH ECMWF EXHIBITING SOME BETTER RUN TO RUN
CONTINUITY IN COMPARISON TO 24 HOURS AGO. FLOW PATTERN QUITE COMPLEX
FOR THIS PERIOD WITH MAIN QUESTION REGARDING PHASING ISSUES OF NEXT
SOUTHERN STEAM UPPER TROUGH WITH ACTIVE SOUTHERN CANADIAN NORTHERN
STREAM. GENERALLY FOLLOWED HPC PREFERENCE OF A SLIGHTLY SLOWER THAN
ECMWF SOLUTION GIVEN EXPECTED FAST BIASED EJECTION OF SOUTHWEST US
WAVE. THIS CENTERS HIGHEST POPS IN THE THURS NIGHT PERIOD BUT
DEPENDING ON RATE OF EJECTION OF THIS TROUGH...PRECIP MAY EVENTUALLY
HAVE TO BE ADDED INTO FRIDAY. HARD TO DEVIATE AT THIS TIME FROM A
BROADBRUSH RAIN/SNOW PTYPE MENTION FOR THURSDAY/THURSDAY NIGHT GIVEN
EXPECTED MARGINAL LOW LEVEL THERMAL PROFILES DURING THIS PERIOD.
TEMPS SHOULD TREND SLIGHTLY ABOVE SEASONABLE NORMS FOR THE WED-FRI
PERIOD WITH SOME SUGGESTIONS OF A BRIEF SHOT OF COLD ADVECTION
TOWARD THE END OF THE PERIOD AS LARGER SCALE NORTHERN STREAM TROUGH
DIGS ACROSS THE GREAT LAKES REGION.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR INZ004-
014.
MI...WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR MIZ077.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST MONDAY FOR LMZ043-046.
&&
$$
SHORT TERM...FISHER
LONG TERM...MARSILI
AVIATION...MURPHY
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
650 AM EST SAT FEB 11 2012
.AVIATION...
12Z TAFS...LAKE EFFECT SNOW EVENT ALREADY UNDERWAY ACROSS NORTHERN
INDIANA WILL BE THE MAIN FOCUS FOR THE AVIATION FORECAST. BACKING
OF LARGER SCALE LOW LEVEL WIND FLOW HAS TAKEN MAIN LAKE EFFECT
BAND ACROSS EASTERN LAKE MICHIGAN INTO NORTHWEST INDIANA THIS
MORNING. THE COMBINATION OF HEAVIER BURSTS OF SNOW WITH GUSTY
NORTH WINDS/BLSN WILL RESULT IN VSBYS DROPPING TO A HALF MILE OR LESS
AT TIMES THROUGH 15Z OR 16Z AT KSBN. AFTER 16Z...INVERSION HEIGHTS
SHOULD BEGIN TO DROP MORE STEADILY...WHICH LOWERS THE CONFIDENCE
IN SNOW RATES AFTER THIS TIME. OVERALL...NOT MUCH CHANGE TO THE
06Z TAFS WITH RESPECT TO PERIOD OF HEAVIEST SNOW AT KSBN FROM 12Z
TO 16Z. WINDS HAVE TEMPORARILY SUBSIDED AT KSBN IN ASSOCIATION
WITH LAKE INDUCED CONVERGENCE AXIS...BUT EXPECTING GUSTS BACK
CLOSE TO 25 KNOTS BY MID MORNING WITH INCREASING MIXING. LOW LEVEL
TRAJECTORIES WILL SUPPORT CONTINUED SCT SNOW SHOWERS INTO THE
AFTERNOON...WITH A PERIOD OF SOME SCT SNOW SHOWERS AND FLURRIES
POSSIBLE AT KFWA LATE MORNING THROUGH MID AFTERNOON. MVFR
CONDITIONS THIS AFTERNOON SHOULD TREND TO VFR THIS EVENING AS
DRIER LOW LEVEL AIR ADVECTS SOUTHEASTWARD.
&&
.PREV DISCUSSION... /ISSUED 423 AM EST SAT FEB 11 2012/
SHORT TERM.../TODAY THROUGH SUNDAY NIGHT/
..LAKE EFFECT SNOW EVENT UNDERWAY...
ARCTIC COLD FRONT HAS SWEPT ACROSS THE FORECAST AREA WITH
TEMPERATURES IN THE TEENS AND DEWPTS FALLING INTO THE SINGLE DIGITS.
SOME LEFTOVER LIGHT SNOW WAS SEEN ON OBS AND RADAR ACROSS PORTIONS
OF NORTHEASTERN INDIANA AND NORTHWESTERN OHIO. MAIN FOCUS WAS WELL
DEFINED INTENSE LAKE EFFECT SNOW BAND THAT RAPIDLY DEVELOPED ACROSS
LAKE AND PORTER COUNTIES THIS PAST EVENING AND AFTER A BRIEF SHIFT
WEST AND INCREASE IN EASTERN PROGRESS HAS BEEN NOTED WITH THE BAND
CURRENTLY SITUATED ACROSS LAPORTE AND STARKE COUNTIES AHEAD OF
SCHEDULE. REPORT FROM VALPO UNIV OF LIGHTNING WAS RECEIVED AS THE
HEAVIEST PART OF THE BAND SHIFTED ACROSS THAT AREA. RADAR TRENDS
ACROSS THE FORECAST AREA HAS SHOWN A DOWNWARD TREND IN SOUTHERN
EXTENT AND INTENSITY OF THE BAND. UPSTREAM ACROSS THE LAKE KGRR
RADAR SHOWING AN INCREASE IN RETURNS AS THE BAND SHIFTED MORE ALONG
THE EASTERN SHORE OF THE LAKE. A FEW RUNS OF THE HRRR SUGGESTED THIS
MAY OCCUR WITH THE INITIAL BAND WEAKENING WITH TIME AS CONVERGENCE
WEAKENED AND MORE OF A MULTI BAND SETUP BEGAN TO ESTABLISH WITH TIME
THIS MORNING. WHILE FULL WARNING CRITERIA MAY NOT BE
MET...DETERIORATING CONDITIONS STILL WARRANT HOLDING ONTO CURRENT
HEADLINES. RISK FOR WARNING CRITERIA STILL POSSIBLE OVER BERRIEN
COUNTY AS BAND REORIENTS AND PERSISTS INTO EARLY AFTERNOON. DID
EXPAND POPS FURTHER SOUTH AND EAST AS INLAND EXTENT OF BANDS MAY
INCREASE AS OVERALL FLOW INCREASES SOMEWHAT WITH STRONGER GRADIENT
SHIFTING ACROSS THE AREA. WOULD NOT EXPECT MUCH IMPACT BUT FELT AT
LEAST CHC POPS WERE NEEDED DOWNSTREAM OF THE BAND.
GIVEN UNCERTAINTY OF EXTENT AND INTENSITY OF HEAVIEST BANDS HAVE
WENT WITH LIKELY POPS INTO THE AFTERNOON WITH ONLY LIGHT ADDITIONAL
ACCUMS.
NW FLOW WILL PERSIST ACROSS THE REGION INTO SUNDAY. HOWEVER...LL
TEMPS WILL QUICKLY UNDERGO MODERATION TONIGHT INTO SUNDAY CAUSING
DELTA T`S TO DECREASE AND INVERSION HGTS TO LOWER. THE RESULT WILL
BE SOME LINGERING VERY LIGHT SNOW OR FLURRIES INTO TONIGHT BEFORE
ENDING. SUNDAY/SUNDAY NIGHT APPEAR DRY AT THIS POINT WITH HIGH
PRESSURE BUILDING IN. MEAN RH VALUES DROPS CONSIDERABLY BY SUNDAY
AFTERNOON INTO SUNDAY NIGHT...ALLOWING FOR MOSTLY CLEAR TO CLEAR
SKIES AND MODERATING TEMPS.
&&
LONG TERM...MONDAY THROUGH FRIDAY
OVERALL VERY FEW CHANGES REQUIRED TO THE LONG TERM PERIOD FOR THIS
FORECAST CYCLE.
FOR MONDAY...LOW LEVEL ANTICYCLONE WILL SHIFT EASTWARD THROUGH THE
LOWER MS RIVER VALLEY INTO THE SOUTHEAST US...EVENTUALLY ALLOWING
LOW LEVEL RETURN SOUTHWESTERLY FLOW TO SETUP. A SHEARED UPPER VORT
MAX DIVORCED FROM STRONGER STEERING FLOW AS A RESULT OF WESTERN
CONUS SPLIT FLOW SHOULD GRADUALLY GET PHASED WITH A MORE AMPLIFIED
SOUTHERN STREAM TROUGH KICKING OUT OF THE FOUR CORNERS REGION. AS
THIS OCCURS...STRONGER LOW LEVEL THETAE ADVECTION/ISENTROPIC LIFT
SHOULD BE FOCUSED JUST WEST OF THE AREA. NAM/GFS ISENTROPIC PROGS IN
290-280K LAYER DO INDICATE MORE SUBSTANTIAL LOWERING OF
CONDENSATIONAL PRESSURE DEFICITS THROUGHOUT THIS LAYER BY LATE IN
THE DAY MONDAY...BUT SUBCLOUD LAYER MAY BE TOO DRY FOR MOST AREAS TO
RECEIVE ANY PRECIP MONDAY AFTERNOON. A SHARP LOW LEVEL GRADIENT
NOTED IN MIXING RATIOS THROUGHOUT THIS LAYER FROM WEST TO EAST ON
MONDAY...AND PREVIOUS POP GRADIENT MONDAY AFTERNOON FROM LOW CHANCE
WEST TO SLIGHT CHANCE EAST STILL APPEARS REASONABLE. STRONGER
ISENTROPIC UPGLIDE AND MID LEVEL FORCING TO MOVE IN FOR MONDAY NIGHT
WHICH STILL APPEARS TO BE SHAPING UP AS A HIGH POP/LOW QPF EVENT
BASED ON A RELATIVELY SHORT DURATION OF BETTER LOW/MID LEVEL
MOISTURE PROFILES AND RATHER DISJOINTED NATURE OF MID/UPPER LEVEL
FORCING WITH ONLY PARTIAL PHASING OF THESE AFOREMENTIONED SHORT
WAVES. MOST OF PRECIP EXPECTED MONDAY NIGHT BUT WILL CONTINUE TO
CARRY CHANCE -SN MENTION INTO TUESDAY WITH LAGGING SHORT WAVE SLOW
TO EXIT THE AREA. PRECIP MAY END AS A PERIOD OF DRIZZLE/FLURRIES
TUESDAY NIGHT...ESPECIALLY ACROSS EASTERN AREAS...AS MOISTURE
PROFILES BECOMING INCREASING SHALLOW WITH ONLY WEAK MID LEVEL
FORCING.
MEDIUM RANGE MODELS HAVE STARTED TO CONVERGE A BIT MORE IN REGARDS
TO MID/LATE WEEK SYSTEM WITH ECMWF EXHIBITING SOME BETTER RUN TO RUN
CONTINUITY IN COMPARISON TO 24 HOURS AGO. FLOW PATTERN QUITE COMPLEX
FOR THIS PERIOD WITH MAIN QUESTION REGARDING PHASING ISSUES OF NEXT
SOUTHERN STEAM UPPER TROUGH WITH ACTIVE SOUTHERN CANADIAN NORTHERN
STREAM. GENERALLY FOLLOWED HPC PREFERENCE OF A SLIGHTLY SLOWER THAN
ECMWF SOLUTION GIVEN EXPECTED FAST BIASED EJECTION OF SOUTHWEST US
WAVE. THIS CENTERS HIGHEST POPS IN THE THURS NIGHT PERIOD BUT
DEPENDING ON RATE OF EJECTION OF THIS TROUGH...PRECIP MAY EVENTUALLY
HAVE TO BE ADDED INTO FRIDAY. HARD TO DEVIATE AT THIS TIME FROM A
BROADBRUSH RAIN/SNOW PTYPE MENTION FOR THURSDAY/THURSDAY NIGHT GIVEN
EXPECTED MARGINAL LOW LEVEL THERMAL PROFILES DURING THIS PERIOD.
TEMPS SHOULD TREND SLIGHTLY ABOVE SEASONABLE NORMS FOR THE WED-FRI
PERIOD WITH SOME SUGGESTIONS OF A BRIEF SHOT OF COLD ADVECTION
TOWARD THE END OF THE PERIOD AS LARGER SCALE NORTHERN STREAM TROUGH
DIGS ACROSS THE GREAT LAKES REGION.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER STORM WARNING UNTIL 10 AM CST THIS MORNING FOR INZ003-012.
WINTER WEATHER ADVISORY UNTIL 11 AM EST THIS MORNING FOR INZ013.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR INZ004-
014.
MI...WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR MIZ077.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST MONDAY FOR LMZ043.
SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 7 AM EST MONDAY
FOR LMZ046.
GALE WARNING UNTIL 11 AM EST THIS MORNING FOR LMZ046.
&&
$$
SHORT TERM...FISHER
LONG TERM...MARSILI
AVIATION...MARSILI
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
423 AM EST SAT FEB 11 2012
.SHORT TERM.../TODAY THROUGH SUNDAY NIGHT/
...LAKE EFFECT SNOW EVENT UNDERWAY...
ARCTIC COLD FRONT HAS SWEPT ACROSS THE FORECAST AREA WITH
TEMPERATURES IN THE TEENS AND DEWPTS FALLING INTO THE SINGLE DIGITS.
SOME LEFTOVER LIGHT SNOW WAS SEEN ON OBS AND RADAR ACROSS PORTIONS
OF NORTHEASTERN INDIANA AND NORTHWESTERN OHIO. MAIN FOCUS WAS WELL
DEFINED INTENSE LAKE EFFECT SNOW BAND THAT RAPIDLY DEVELOPED ACROSS
LAKE AND PORTER COUNTIES THIS PAST EVENING AND AFTER A BRIEF SHIFT
WEST AND INCREASE IN EASTERN PROGRESS HAS BEEN NOTED WITH THE BAND
CURRENTLY SITUATED ACROSS LAPORTE AND STARKE COUNTIES AHEAD OF
SCHEDULE. REPORT FROM VALPO UNIV OF LIGHTNING WAS RECEIVED AS THE
HEAVIEST PART OF THE BAND SHIFTED ACROSS THAT AREA. RADAR TRENDS
ACROSS THE FORECAST AREA HAS SHOWN A DOWNWARD TREND IN SOUTHERN
EXTENT AND INTENSITY OF THE BAND. UPSTREAM ACROSS THE LAKE KGRR
RADAR SHOWING AN INCREASE IN RETURNS AS THE BAND SHIFTED MORE ALONG
THE EASTERN SHORE OF THE LAKE. A FEW RUNS OF THE HRRR SUGGESTED THIS
MAY OCCUR WITH THE INITIAL BAND WEAKENING WITH TIME AS CONVERGENCE
WEAKENED AND MORE OF A MULTI BAND SETUP BEGAN TO ESTABLISH WITH TIME
THIS MORNING. WHILE FULL WARNING CRITERIA MAY NOT BE
MET...DETERIORATING CONDITIONS STILL WARRANT HOLDING ONTO CURRENT
HEADLINES. RISK FOR WARNING CRITERIA STILL POSSIBLE OVER BERRIEN
COUNTY AS BAND REORIENTS AND PERSISTS INTO EARLY AFTERNOON. DID
EXPAND POPS FURTHER SOUTH AND EAST AS INLAND EXTENT OF BANDS MAY
INCREASE AS OVERALL FLOW INCREASES SOMEWHAT WITH STRONGER GRADIENT
SHIFTING ACROSS THE AREA. WOULD NOT EXPECT MUCH IMPACT BUT FELT AT
LEAST CHC POPS WERE NEEDED DOWNSTREAM OF THE BAND.
GIVEN UNCERTAINTY OF EXTENT AND INTENSITY OF HEAVIEST BANDS HAVE
WENT WITH LIKELY POPS INTO THE AFTERNOON WITH ONLY LIGHT ADDITIONAL
ACCUMS.
NW FLOW WILL PERSIST ACROSS THE REGION INTO SUNDAY. HOWEVER...LL
TEMPS WILL QUICKLY UNDERGO MODERATION TONIGHT INTO SUNDAY CAUSING
DELTA T`S TO DECREASE AND INVERSION HGTS TO LOWER. THE RESULT WILL
BE SOME LINGERING VERY LIGHT SNOW OR FLURRIES INTO TONIGHT BEFORE
ENDING. SUNDAY/SUNDAY NIGHT APPEAR DRY AT THIS POINT WITH HIGH
PRESSURE BUILDING IN. MEAN RH VALUES DROPS CONSIDERABLY BY SUNDAY
AFTERNOON INTO SUNDAY NIGHT...ALLOWING FOR MOSTLY CLEAR TO CLEAR
SKIES AND MODERATING TEMPS.
&&
.LONG TERM...MONDAY THROUGH FRIDAY
OVERALL VERY FEW CHANGES REQUIRED TO THE LONG TERM PERIOD FOR THIS
FORECAST CYCLE.
FOR MONDAY...LOW LEVEL ANTICYCLONE WILL SHIFT EASTWARD THROUGH THE
LOWER MS RIVER VALLEY INTO THE SOUTHEAST US...EVENTUALLY ALLOWING
LOW LEVEL RETURN SOUTHWESTERLY FLOW TO SETUP. A SHEARED UPPER VORT
MAX DIVORCED FROM STRONGER STEERING FLOW AS A RESULT OF WESTERN
CONUS SPLIT FLOW SHOULD GRADUALLY GET PHASED WITH A MORE AMPLIFIED
SOUTHERN STREAM TROUGH KICKING OUT OF THE FOUR CORNERS REGION. AS
THIS OCCURS...STRONGER LOW LEVEL THETAE ADVECTION/ISENTROPIC LIFT
SHOULD BE FOCUSED JUST WEST OF THE AREA. NAM/GFS ISENTROPIC PROGS IN
290-280K LAYER DO INDICATE MORE SUBSTANTIAL LOWERING OF
CONDENSATIONAL PRESSURE DEFICITS THROUGHOUT THIS LAYER BY LATE IN
THE DAY MONDAY...BUT SUBCLOUD LAYER MAY BE TOO DRY FOR MOST AREAS TO
RECEIVE ANY PRECIP MONDAY AFTERNOON. A SHARP LOW LEVEL GRADIENT
NOTED IN MIXING RATIOS THROUGHOUT THIS LAYER FROM WEST TO EAST ON
MONDAY...AND PREVIOUS POP GRADIENT MONDAY AFTERNOON FROM LOW CHANCE
WEST TO SLIGHT CHANCE EAST STILL APPEARS REASONABLE. STRONGER
ISENTROPIC UPGLIDE AND MID LEVEL FORCING TO MOVE IN FOR MONDAY NIGHT
WHICH STILL APPEARS TO BE SHAPING UP AS A HIGH POP/LOW QPF EVENT
BASED ON A RELATIVELY SHORT DURATION OF BETTER LOW/MID LEVEL
MOISTURE PROFILES AND RATHER DISJOINTED NATURE OF MID/UPPER LEVEL
FORCING WITH ONLY PARTIAL PHASING OF THESE AFOREMENTIONED SHORT
WAVES. MOST OF PRECIP EXPECTED MONDAY NIGHT BUT WILL CONTINUE TO
CARRY CHANCE -SN MENTION INTO TUESDAY WITH LAGGING SHORT WAVE SLOW
TO EXIT THE AREA. PRECIP MAY END AS A PERIOD OF DRIZZLE/FLURRIES
TUESDAY NIGHT...ESPECIALLY ACROSS EASTERN AREAS...AS MOISTURE
PROFILES BECOMING INCREASING SHALLOW WITH ONLY WEAK MID LEVEL
FORCING.
MEDIUM RANGE MODELS HAVE STARTED TO CONVERGE A BIT MORE IN REGARDS
TO MID/LATE WEEK SYSTEM WITH ECMWF EXHIBITING SOME BETTER RUN TO RUN
CONTINUITY IN COMPARISON TO 24 HOURS AGO. FLOW PATTERN QUITE COMPLEX
FOR THIS PERIOD WITH MAIN QUESTION REGARDING PHASING ISSUES OF NEXT
SOUTHERN STEAM UPPER TROUGH WITH ACTIVE SOUTHERN CANADIAN NORTHERN
STREAM. GENERALLY FOLLOWED HPC PREFERENCE OF A SLIGHTLY SLOWER THAN
ECMWF SOLUTION GIVEN EXPECTED FAST BIASED EJECTION OF SOUTHWEST US
WAVE. THIS CENTERS HIGHEST POPS IN THE THURS NIGHT PERIOD BUT
DEPENDING ON RATE OF EJECTION OF THIS TROUGH...PRECIP MAY EVENTUALLY
HAVE TO BE ADDED INTO FRIDAY. HARD TO DEVIATE AT THIS TIME FROM A
BROADBRUSH RAIN/SNOW PTYPE MENTION FOR THURSDAY/THURSDAY NIGHT GIVEN
EXPECTED MARGINAL LOW LEVEL THERMAL PROFILES DURING THIS PERIOD.
TEMPS SHOULD TREND SLIGHTLY ABOVE SEASONABLE NORMS FOR THE WED-FRI
PERIOD WITH SOME SUGGESTIONS OF A BRIEF SHOT OF COLD ADVECTION
TOWARD THE END OF THE PERIOD AS LARGER SCALE NORTHERN STREAM TROUGH
DIGS ACROSS THE GREAT LAKES REGION.
&&
.AVIATION...
06Z TAFS.
SYNOPTIC SNOW SHOULD BEGIN TO MOVE OUT OF KFWA OVER THE NEXT FEW
HOURS WITH ATTENTION TURNING TO INTENSE LAKE EFFECT SNOW BAND
CURRENTLY ACROSS NORTHWEST INDIANA. LOW LEVEL WINDS SHOULD
CONTINUE TO BACK THROUGH THE OVERNIGHT HOURS ALLOWING THIS BAND TO
EVENTUALLY SHIFT EASTWARD AND AFFECT KSBN BY THE 11Z-13Z
TIME FRAME. HAVE MAINTAINED IDEA FROM PREVIOUS TAFS WITH A PERIOD
OF LIFR CONDITIONS IN ASSOCIATION WITH THIS BAND GIVEN MODERATE TO
STRONG LAKE INDUCED INSTABILITY AND A MORE FAVORABLE NORTH
NORTHWEST FETCH FOR KSBN. IT APPEARS AS THOUGH THERE WILL BE A
THREE HOUR WINDOW OF INTENSE SNOWFALL RATES OF POTENTIALLY 1 TO 2
INCHES PER HOUR AT KSBN IN THE 12Z TO 16Z TIME FRAME. BLOWING SNOW
ALSO LIKELY TO CAUSE SOME CONTINUED VSBY RESTRICTIONS THROUGH THE
LATE MORNING HOURS. INVERSION HEIGHTS WILL BEGIN TO LOWER BY LATE
MORNING WITH STRONGER LAKE EFFECT SNOW SHOWERS SHIFTING NORTH AND
EAST OF KSBN LATE MORNING. DESPITE LOWERING INVERSION
HEIGHTS...DID KEEP SCT SNOW SHOWERS AND FLURRIES THROUGH THIS
FORECAST VALID PERIOD ALONG WITH MVFR CIGS.
&&
.MARINE...
WILL CONTINUE GALE WARNINGS THROUGH THE MORNING. SUSTAINED WINDS
IN THE 35 TO 40 KT RANGE HAVE PERSISTED FOR SEVERAL HOURS AT
MICHIGAN CITY WITH GUSTS OF 40 TO 44 KTS. WINDS MUCH LIGHTER AT ST
JOE/BENTON HARBOR BUT EXPECT THEM TO INCREASE AS STRONG GRADIENT
SHIFTS OVER HEAD THIS MORNING.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER STORM WARNING UNTIL 10 AM CST THIS MORNING FOR INZ003-012.
WINTER WEATHER ADVISORY UNTIL 11 AM EST THIS MORNING FOR INZ013.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR INZ004-
014.
MI...WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR MIZ077.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST SUNDAY FOR LMZ043-046.
GALE WARNING UNTIL 5 AM EST EARLY THIS MORNING FOR LMZ043-046.
&&
$$
SHORT TERM...FISHER
LONG TERM...MARSILI
AVIATION...MARSILI
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
109 AM EST SAT FEB 11 2012
.AVIATION...
06Z TAFS.
SYNOPTIC SNOW SHOULD BEGIN TO MOVE OUT OF KFWA OVER THE NEXT FEW
HOURS WITH ATTENTION TURNING TO INTENSE LAKE EFFECT SNOW BAND
CURRENTLY ACROSS NORTHWEST INDIANA. LOW LEVEL WINDS SHOULD
CONTINUE TO BACK THROUGH THE OVERNIGHT HOURS ALLOWING THIS BAND TO
EVENTUALLY SHIFT EASTWARD AND AFFECT KSBN BY THE 11Z-13Z
TIME FRAME. HAVE MAINTAINED IDEA FROM PREVIOUS TAFS WITH A PERIOD
OF LIFR CONDITIONS IN ASSOCIATION WITH THIS BAND GIVEN MODERATE TO
STRONG LAKE INDUCED INSTABILITY AND A MORE FAVORABLE NORTH
NORTHWEST FETCH FOR KSBN. IT APPEARS AS THOUGH THERE WILL BE A
THREE HOUR WINDOW OF INTENSE SNOWFALL RATES OF POTENTIALLY 1 TO 2
INCHES PER HOUR AT KSBN IN THE 12Z TO 16Z TIME FRAME. BLOWING SNOW
ALSO LIKELY TO CAUSE SOME CONTINUED VSBY RESTRICTIONS THROUGH THE
LATE MORNING HOURS. INVERSION HEIGHTS WILL BEGIN TO LOWER BY LATE
MORNING WITH STRONGER LAKE EFFECT SNOW SHOWERS SHIFTING NORTH AND
EAST OF KSBN LATE MORNING. DESPITE LOWERING INVERSION
HEIGHTS...DID KEEP SCT SNOW SHOWERS AND FLURRIES THROUGH THIS
FORECAST VALID PERIOD ALONG WITH MVFR CIGS.
&&
.UPDATE...
UPDATED ZONES JUST SENT TO REMOVE ALL WINTER WEATHER HEADLINES
EXCEPT FAR NW/W COUNTIES WHERE LAKE EFFECT CONCERNS WILL INCREASE
IN THE COMING HOURS.
LARGE SCALE SYNOPTIC FORCING HAS WOUND DOWN RAPIDLY OVER THE PAST
COUPLE OF HOURS. FLURRIES OR AREAS OF LIGHT SNOW WILL STILL BE
SEEN EAST OF US 131 THROUGH THE REMAINDER OF THE NIGHT. EVEN
THOUGH SOME BLOWING AND DRIFTING WILL TAKE PLACE...OVERALL THREAT
HAD DIMINISHED SO WILL GET RID OF HEADLINES.
FOCUS WILL THEN SHIFT TO SINGLE LAKE EFFECT BAND THAT HAS DROPPED
UPWARDS OF 6 TO 10 INCHES OF SNOW ACROSS PORTIONS OF PORTER
COUNTY. SECONDARY COLD FRONT DROPPED THROUGH THE AREA CAUSING A
BRIEF SHIFT WESTWARD IN THE BAND AND SLIGHT DECREASE IN INTENSITY.
WITH THE FRONT HAVING CLEARED THAT AREA...BAND WAS RAPIDLY GAINING
STRENGTH ONCE AGAIN...BUT WAS ALSO BEGINNING TO TRANSITION EAST A
BIT FASTER THAN PREVIOUSLY FORECAST. BY 130 AM EST/1230 AM CST/
BAND WILL LIKELY BE IN OR CLOSE TO WESTERN PORTIONS OF LA PORTE
AND STARKE COUNTIES WHERE 1 TO 2 INCHES PER HOURS AND NEAR
WHITEOUT CONDITIONS MAY BE SEEN FOR SEVERAL HOURS. HRRR RUNS DO
PROGRESS THE BAND SLOWY EASTWARD...POSSIBLY REACHING THE SOUTH
BEND AREAS IN THE 9 TO 12Z WINDOW. FOR NOW WILL LEAVE LAKE EFFECT
RELATED HEADLINES IN PLACE AND RE-EVALUATE IN A FEW HOURS WITH
NORMAL PACKAGE ISSUANCE.
.PREV DISCUSSION... /ISSUED 424 PM EST FRI FEB 10 2012/
SHORT TERM...
TONIGHT THROUGH SATURDAY NIGHT. MAJOR CHGS WRT WDSPRD SYNOPTIC SNWFL
FOLLOWED BY SIG LES EVENT...THOUGH ALL IN ALL IN STEP WITH TRENDS
SEEN THROUGH PAST 36 HRS. SIG EWD PLACEMENT OF MAJOR AXIS BAND NOTE
IN NMM/ARW/NAM AND HAVE BUY IN GIVEN NEAR TERM DVLPMNTS WRT
SWRN/WCNTL MICHIGAN SFC RESPONSE SEEN ERLIER TODAY. A DEEPER MORE
STACKED SYSTEM GOING INTO SAT MORNING ACRS LWR GRTLKS TO PROVIDE FOR
MORE WELL DVLPD MAJOR AXIS BAND AND FURTHERMORE KEEPS DRY AIR ACRS
WI IN PLACE AND NOT ALLOW NEAR AS MUCH ENTRAINMENT INTO BAND AS WAS
FEARED YDAY AND ERLIER TDY. FURTHERMORE LESSER SHEARED AND MORE
CYCLONIC UPSTREAM LAKE SUPR/NRN LAKE MICHIGAN SHOULD AID IN FORMING
MORE RESOLUTE BAND. NEARNESS OF EVENT COMBINED WITH INCRSD INTENSITY
OF PRESENT SYNOPTIC EVENT UNDERWAY NECESSITATES HOISTING OF
WARNINGS/ADVISORIES. FURTHER COMPLICATING MATTERS IS VERY BRIEF LULL
BETWN DWINDLING SYNOPTIC EVENT AND LES INTO NCNTL IN. TOO AVOID
MULTIPLE HEADLINES HAVE OPTED FOR MORE GENERAL WINTER WX
WARNING/ADVISORIES AND HOLD LONGER DURATION TO LES TARGETED
COUNTIES. BEST THERMAL INSTABILITY NOTED AROUND 12 UTC SAT WITH
LK/8H THERMAL DIFFERENTIALS NEARING 20C. ALSO OF NOTE IS SRN LAKE
MICHIGAN MODEL MUCAPE OF 150 J/KG COINCIDENT WITH LONG AXIS LLVL
CONVERGENCE. DEEPER MOISTURE INTO DGZ SUGGESTIVE OF LARGE AGGREGATED
FLAKES AND HAVE FINER DETAIL/HIGHER LIQUID TO SNOW RATIOS IN LES
AREAS DIFFERENTIATING DEPARTING SERN CWA SYNOPTIC EVENT THAT SHOULD
HAVE RATIOS CLOSER TO CLIMO. WIDE VARIABILITY OF SNOWFALL AMOUNTS
ANTICIPATED WITH HVST AMOUNTS ALONG/W OF 421 EXPECTED WHERE
GREATEST SNOWFALL RATE POTNL MAINTAINS LONGEST DURATION. THEREAFTER
BACKING CBL TO 330 DEGREES BY MIDDAY SAT AND 310 BY LATE AFTN WITH
LES BAND SWINGING NORTHEAST WHILST LAKE INDUCED EQL LOWERS FM 10KFT
TO NEAR 5KFT.
LONG TERM... / SUNDAY THROUGH FRIDAY /
UPPER LEVEL HEIGHTS WILL BE ON THE RISE SUNDAY...BRINGING ABOUT A
MODEST RESPONSE THERMALLY AS 925/850 MB TEMPS WARM AROUND 10 DEG C
FROM SATURDAY INTO SUNDAY. HOWEVER...HIGHS WILL LIKELY ONLY RECOVER
INTO THE UPPER 20S TO NEAR 30F GIVEN SHALLOW MIXING. ALSO...BRISK NW
WINDS WILL LIKELY PERSIST INTO SUNDAY AS A LOW LVL ANTICYCLONE
DRIFTS SEWD TOWARDS THE MID/LOWER MS VALLEY. THIS LOW LVL TRAJECTORY
SHOULD ALLOW LAKE CLOUDS TO LINGER FOR MUCH OF THE DAY ACROSS
NORTHERN PORTIONS OF THE FA AS BOUNDARY LAYER MOISTURE LOCKS IN
UNDER A STRENGTHENING SUBSIDENCE INVERSION.
QUASI-ZONAL SPLIT FLOW WILL TAKE HOLD ON THE LOWER 48 NEXT WEEK WITH
TEMPS MODERATING TO ABOVE NORMAL VALUES BY WEDNESDAY. A LIGHT SNOW
EVENT CONTINUES TO LOOK POSSIBLE LATE MONDAY INTO TUESDAY AS LOWER
AMPLITUDE SHORTWAVE ENERGY PROPAGATES INTO THE MIDWEST. HEIGHT FALLS
WITH THIS ENERGY WILL ELICIT ENOUGH OF A LOW LVL RESPONSE TO SUPPORT
INCREASING ISENTROPIC UPGLIDE AND THETA-E RISES MAINLY IN THE 9-7H
LAYER. MODEL QPF HAS REMAINED RELATIVELY CONSISTENT...GENERALLY BTW
A TENTH AND TWO TENTHS...HINTING AT A 0.5-2.0" TYPE EVENT. OPTED TO
REMAIN SOMEWHAT CONSERVATIVE WRT POPS DURING THIS TIME AS MID/UPPER
LVL SUPPORT APPEARS DISJOINTED GIVEN UNCERTAINTIES WRT
TIMING/INTERACTION BTW STREAMS.
LITTLE TO NO CHANGES TO THE FCST BEYOND WEDNESDAY AS MODELS CONTINUE
TO SHOW LITTLE RUN-TO-RUN CONSISTENCY. THIS IS EXPECTED IN A SPLIT
FLOW REGIME AS LARGE DIFFERENCES REMAIN WITH TIMING AND INTERACTION
OF STREAMS. SOME GUIDANCE INDICATES LESS RIDGING ACROSS THE SE CONUS
WITH MORE IN THE WAY OF MID LVL CONFLUENCE LOCALLY SUPPORTING DRY
CONDITIONS AND LOW LVL RIDGING. THE LATEST ECMWF AND 00Z/06Z GFS
SHOW GREATER AMPLIFICATION/SE RIDGING ALLOWING A STRONGER SOUTHERN
STREAM SHORTWAVE TO BRING HEAVIER PCPN NEWD INTO THE FA BY THURSDAY
OR FRIDAY. HARD TO PUT MORE STOCK ON EITHER SOLUTION GIVEN THE LACK
OF INTRA-RUN CONSISTENCY SEEN IN THE GFS AND ECMWF.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER STORM WARNING UNTIL 10 AM CST SATURDAY FOR INZ003-012.
WINTER WEATHER ADVISORY UNTIL 11 AM EST THIS MORNING FOR INZ013.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR INZ004-
014.
MI...WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR MIZ077.
OH...NONE.
LM...SMALL CRAFT ADVISORY FROM 5 AM EARLY THIS MORNING TO 7 PM EST
SUNDAY FOR LMZ043-046.
GALE WARNING UNTIL 5 AM EST EARLY THIS MORNING FOR LMZ043-046.
&&
$$
SHORT TERM...MURPHY
LONG TERM...STEINWEDEL
AVIATION...MARSILI
UPDATE...FISHER
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1129 PM CST FRI FEB 10 2012
.AVIATION...
VFR CONDITIONS TO PREVAIL THROUGH TAF CYCLE. TIGHT PRESSURE GRADIENT
BETWEEN CANADIAN HIGH BUILDING THROUGH THE PLAINS AND LOW TO THE
EAST WILL CONTINUE GUSTY N/NW WINDS AT 10-20 KTS FOR MUCH OF THE PD.
&&
.PREV DISCUSSION... /ISSUED 305 PM CST FRI FEB 10 2012/
SYNOPSIS...
12Z UA ANALYSIS HAS A COLD FRONT FROM THE MACKINAC STRAITS INTO
NORTHERN KANSAS WITH TROFS FROM THE MID ATLANTIC BACK INTO THE
PLAINS. SATELLITE AND RADAR TRENDS THROUGH MID AFTERNOON SHOWS AREAS
OF LIGHT SNOW AND SNOW SHOWERS ACROSS THE WESTERN GREAT LAKES WITH
CLEARING SKIES IN MINNESOTA.
18Z SFC ANALYSIS HAS A LOW JUST EAST OF KMKG AND ANOTHER JUST
NORTHEAST OF KORD. THE ARCTIC FRONT RAN FROM THE SECOND LOW
SOUTHWEST INTO NORTHERN TEXAS. DEW POINTS WERE IN THE 20S AND 30S
AHEAD AND IMMEDIATELY BEHIND THE FRONT WITH SINGLE DIGITS ABOVE AND
BELOW ZERO ACROSS THE NORTHERN PLAINS.
SHORT TERM...TONIGHT AND SATURDAY...
RUC TRENDS USING THE 900-950MB AND 0.5-1.0KM RH LAYERS ARE DOING A
REASONABLY GOOD JOB OF DEPICTING THE CURRENT CLOUD COVER ACROSS THE
AREA. SNOW SHOWERS/FLURRIES WILL CONTINUE THROUGH THE AFTERNOON WITH
MOST SNOW SHOWERS DISSIPATING WITH SUNSET. STRONG CYCLONIC FLOW AND
VORT MAXES ROTATING THROUGH THE AREA SHOULD PROLONG THE FLURRIES
INTO THE EARLY EVENING OVER ROUGHLY THE EASTERN HALF OF THE CWFA.
GENERAL ACCUMULATIONS SHOULD RANGE FROM A TRACE TO A DUSTING.
A FEW HOURS AGO THE RUC WAS INDICATING CLEARING WOULD OCCUR FROM THE
NORTHWEST AFTER MID EVENING AND THEN TAKE MOST OF THE NIGHT TO CLEAR
OUT EAST OF THE MISSISSIPPI. HOWEVER...A NEW CLEAR AREA HAS
DEVELOPED IN AN AREA OF SUBSIDENCE ACROSS NORTHERN WISCONSIN. RUC
TRENDS USING THE 900-950MB AND 0.5-1.0KM RH LAYERS ARE NOW
SUGGESTING THE CWFA MAY SEE CLEARING STARTING FROM THE NORTHWEST AND
WEST AFTER MID-EVENING AND ALSO FROM THE NORTHEAST. IF THIS DOES
OCCUR THEN ROUGHLY THE SOUTHEAST QUADRANT OF THE CWFA WOULD BE THE
LAST TO CLEAR OUT AFTER MIDNIGHT.
TEMPERATURES WILL BE INTERESTING. AREAS THAT CLEAR OUT SOONER WILL
DROP QUICKLY DUE TO THE CAA THAT WILL CONTINUE OVERNIGHT. THE FACT
THAT WINDS WILL NOT DECOUPLE FROM THE BOUNDARY LAYER WILL BE WHAT
KEEPS LOWS ABOVE ZERO. FAVORED COLD AREAS IN THE WAPSI AND SAUK
VALLEYS MAY APPROACH ZERO IN SPITE OF THE WINDS. THE WIND AND
TEMPERATURES WILL DROP WIND CHILLS WELL BELOW ZERO BUT ARE EXPECTED
TO REMAIN JUST ABOVE ADVISORY CRITERIA.
SATURDAY WILL BE A COLD BRISK DAY. ARCTIC HIGH PRESSURE BUILDING
INTO THE AREA WILL RESULT IN SUNNY SKIES BUT WIND CHILLS ARE
EXPECTED TO REMAIN BELOW ZERO FOR MUCH OF THE MORNING. MAX
TEMPERATURES WILL STRUGGLE TO GET INTO THE UPPER TEENS AND LOWER 20S
BY MID AFTERNOON.
08..
LONG TERM...SATURDAY NIGHT THROUGH NEXT FRIDAY...
A HIGH PRESSURE RIDGE CENTERED OVER WESTERN IOWA SATURDAY EVENING
WILL MOVE EAST THROUGH THE MID MISSISSIPPI RIVER VALLEY BY MONDAY
MORNING. TEMPERATURES WILL BE THE MAIN CONCERN SATURDAY NIGHT AND
SUNDAY WITH THE RIDGE AXIS JUST WEST OF THE CWFA. THERE SHOULD BE
ENOUGH OF A PRESSURE GRADIENT TO KEEP WINDS FROM DECOUPLING. THE
WIND ALONG ALONG WITH BARE GROUND SHOULD KEEP MIN TEMPS SATURDAY
NIGHT ABOVE ZERO. ALTHOUGH A SMALL PART OF THE SOUTHWEST CWFA COULD
SLIP BELOW ZERO SINCE VISIBLE SATELLITE IMAGERY SHOWS SOME SNOW
COVER NOSING INTO THE AREA. TEMPS ARE EXPECTED TO REBOUND INTO THE
20S FOR SUNDAY.
PRECIPITATION CHANCES ENTER THE PICTURE SUNDAY NIGHT THROUGH TUESDAY
AS RETURN FLOW SETS UP BEHIND THE RETREATING LOW LEVEL RIDGE AND A
SHORT WAVE MOVES FROM THE NORTHERN PLAINS THROUGH THE MID AND UPPER
MISSISSIPPI VALLEY. THE GFS/NAM ARE THE MOST BULLISH ON PRECIP
DURING THIS PERIOD...GENERATING ABOUT 2 TO 3 TENTHS OF INCH WATER
EQUIVALENT WHILE THE ECMWF PRODUCES 1 TO 2 TENTHS. TEMPERATURES
WILL BE COLD ENOUGH THROUGH THE EVENT FOR ALL SNOW. KEPT AMOUNTS
IN THE 1 TO 3 INCH RANGE WITH THE HIGHEST AMOUNTS WEST AND NORTH.
IF THE GFS VERIFIES THEN THE 3 INCH AMOUNTS SHOULD BE REALIZED WHILE
THE ECMWF WOULD SUPPORT AMOUNTS CLOSER TO AN INCH. THE MEASURABLE
SNOW SHOULD END MONDAY EVENING WITH SOME FLURRIES LINGERING INTO
TUESDAY...SPECIALLY EAST OF THE MISSISSIPPI RIVER.
MODELS CONTINUE TO SHOW A SPLIT FLOW REGIME THROUGH THE REST OF THE
FORECAST PERIOD WITH TEMPERATURES RETURNING TO NEAR OR JUST ABOVE
NORMAL. MOST OF THE SOLUTIONS MOVE A NORTHERN STREAM TROF THROUGH
THE REGION THURSDAY OR FRIDAY BUT KEEP THE SYSTEM UN-PHASED AND
MOISTURE STARVED. THE LONE EXCEPTION IS THE 12Z ECMWF WHICH PHASES
THE TROF WITH THE SOUTHERN STREAM...RESULTING IN A MODERATE PRECIP
EVENT FOR THE REGION. AT THIS POINT THERE IS LOW CONFIDENCE IN THE
EXTENDED PROGS SO KEPT SOME SLIGHT CHANCE POPS IN FOR ALL OR PART OF
THE AREA WEDNESDAY THROUGH FRIDAY. ..DLF..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
434 AM MST SAT FEB 11 2012
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 231 AM MST SAT FEB 11 2012
04Z WATER VAPOR IMAGERY INDICATED SHORT WAVE RIDGING ACROSS THE
CENTRAL ROCKIES...WITH CWA ON WESTERN PERIPHERY OF LONG WAVE
TROUGH. PV FIELDS INDICATED SHORT WAVE TROUGH ACROSS MONTANA
MOVING TO THE SOUTHEAST. AT THE SFC...1043MB SFC HIGH WAS BUILDING
INTO THE PLAINS WITH COLD TEMPERATURES ALREADY OCCURRING NEAR THE
CENTER IN SOUTH DAKOTA...WITH AREA OF LIGHT SNOW AND FOG ALONG
WESTERN FLANK OF SFC HIGH ACROSS NW CWA.
MAIN FORECAST CONCERNS WILL BE COVERAGE/INTENSITY/AMOUNTS OF SNOW
THIS MORNING FOLLOWED BY TEMPS THROUGH SUNDAY MORNING.
TODAY-TONIGHT...AREA OF LIGHT TO OCCASIONALLY MODERATE SNOW WILL
CONTINUE THROUGH THE MORNING HOURS...JUST TO THE SOUTH OF STRONG
AREA OF H7-H6 FRONTOGENESIS. GIVEN THE HIGH SNOW TO LIQUID RATIOS
ALREADY OBSERVED (AROUND 20 TO 1 AT GLD AT 6Z) AND POTENTIAL FOR AT
LEAST A FEW STRONGER BANDS GIVEN INSTABILITY PROFILE...EXPECT A SPOT
OR TWO TO SEE A LITTLE OVER 3 INCHES BEFORE SNOW ENDS...AS LAW
ENFORCEMENT REPORTS 1-2 INCHES OF SNOW HAS FALLEN THROUGH 9Z. WITH
SHORT WAVE RIDGE SHIFTING TO THE EAST DURING THE MORNING
HOURS...STATIC STABILITY INCREASING AND FRONTOGENESIS AND JET STREAK
SUPPORT DECREASING THROUGH THE MORNING HOURS EXPECT PRECIPITATION TO
WEAKEN THROUGH THE MORNING HOURS WITH PRECIPITATION CHANCES
DECREASING THROUGH 18Z...AND THINK ANY KIND OF SNOW ADVISORY NOW
WOULD LIKELY BE TOO SHORT LIVED TO BE WORTH WHILE. WITH SNOW
DIMINISHING EXPECT QUIET WEATHER THROUGH THE AFTERNOON AND
EVENING...BUT WITH STRONG WAA EXPECTED TO REDEVELOP OVERNIGHT SOME
ADVECTION FOG/PATCHY FREEZING DRIZZLE STILL POSSIBLE ALTHOUGH LATEST
VERTICAL PROFILES WILL KEEP PROBABILITIES FAIRLY LOW. WITH SFC
RIDGE...CLOUD COVER AND FRESH SNOW COVER THINK TEMPS WILL STRUGGLE
TO CLIMB BACK INTO THE TEENS IN SOME LOCATIONS AND DEPENDING ON THE
STRENGTH OF CAA THE NEXT FEW HOURS...MAY HAVE WIND CHILL ADVISORY
CONDITIONS IN EASTERN CWA.
SUNDAY-MONDAY...SHORT WAVE RIDGE WILL CONTINUE TO SHIFT TO THE EAST
THROUGH THE DAY SUNDAY MORNING AS ANOTHER SHORT WAVE TROUGH MOVES
INTO THE FOUR CORNERS AREA...BEFORE BEGINNING TO LIFT OUT ACROSS THE
PLAINS BY SUNDAY NIGHT. MID LEVEL LAPSE RATES SUGGEST ATMOSPHERE
WILL BE POTENTIALLY UNSTABLE SUNDAY AFTERNOON THROUGH THE
EVENING...BUT AM GOING TO SIDE WITH GEFS POPS FOR THE AFTERNOON
PERIODS AND HOLD OFF ON ANY MEANINGFUL PRECIP CHANCES UNTIL THE
EVENING...WHEN LARGE SCALE FORCING FOR ASCENT AND POTENTIAL
INSTABILITY BETTER ALIGNED. AM A LITTLE MORE CONFIDENT ABOUT PRECIP
POTENTIAL THIS PERIOD...BUT WITH SOME MODELS INDICATING A PRONOUNCED
DRY SLOT AM GOING TO HOLD THINGS IN THE CHANCE RANGE FOR NOW. WHILE
SOUNDINGS SUGGEST A WARM LAYER WILL BE PRESENT THAT COULD
POTENTIALLY CREATE SOME MIXED PHASE ISSUES...WETBULB PROFILES
CONTINUE TO SUGGEST ALL SNOW AND PLAN ON LEAVING PTYPES THAT WAY FOR
THE TIME BEING. SYSTEM SHOULD QUICKLY MOVE TO THE EAST MONDAY
MORNING AND WHILE SOME LIGHT PRECIPITATION POSSIBLE EARLY...WITH
DOWNWARD MOTION QUICKLY OVERSPREADING THE AREA AND POTENTIAL DRY
SLOT NEARBY DO NOT THINK CHANCES WILL BE AS GOOD AS OVERNIGHT
SUNDAY. DID NOT MAKE A LOT OF CHANGES TO CURRENT FORECAST FOR
TEMPS...BUT DID WARM THINGS UP A FEW DEGREES AS APPROACHING SYSTEM
WILL LIKELY SHIFT COLDER AIR MASS EAST AWAY FROM THE AREA.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 231 AM MST SAT FEB 11 2012
WITH AN UPPER LEVEL RIDGE OVER THE TRI-STATE AREA TUESDAY...FOCUS
FOR THIS PERIOD WILL BE THE STORM SYSTEM THAT WILL MOVE INTO THE
AREA TUESDAY NIGHT AND LAST THROUGH WEDNESDAY NIGHT.
MODELS HAVE MOVED THE UPPER LEVEL TROUGH FURTHER NORTH AS IT CROSSES
THE DESERT SOUTHWEST TUESDAY NIGHT. AHEAD OF THE UPPER LEVEL TROUGH
THE LEFT EXIT REGION OF THE 500MB JET MOVES OVER WESTERN PORTIONS OF
THE AREA...BRINGING PRECIPITATION CHANCES WITH IT. GENERALLY PRECIPITATION
CHANCES IMPROVE WEDNESDAY AS THE UPPER LEVEL TROUGH MOVES
THROUGH...THEN BEGIN TO DECLINE DURING THE EVENING AS THE TROUGH MOVES
EAST OUT OF THE AREA.
THE GFS AND ECMWF CONTINUE TO DISAGREE WITH THE TIMING AND PLACEMENT
OF 700-500MB FRONTOGENESIS AND Q-VECTOR CONVERGENCE AS THE STORM
SYSTEM MOVES THROUGH. HOWEVER HIGHER CHANCES SEEMED WARRANTED FOR
MOST OF THE AREA WEDNESDAY AND WEDNESDAY NIGHT SINCE MODELS HAVE
BEEN FAIRLY CONSISTENT WITH THE PATH OF THE UPPER LEVEL TROUGH OVER
NEW MEXICO AND INTO KANSAS.
AN UPPER LEVEL TROUGH DROPS THROUGH THE AREA FROM THE NORTHWEST
BEHIND THE EXITING STORM SYSTEM THURSDAY NIGHT. WITH DRIER AIR IN
PLACE BEHIND THE STORM SYSTEM FROM WEDNESDAY...AM NOT ANTICIPATING
ANY PRECIPITATION WITH THE TROUGH PASSAGE. A SPLIT FLOW PATTERN
THEN SETS UP OVER THE AREA FRIDAY WITH AN UPPER LEVEL TROUGH OVER
THE GREAT LAKES AND A CLOSED LOW OVER NORTHERN MEXICO.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 419 AM MST SAT FEB 11 2012
MVFR TO VFR CONDITIONS WILL BE POSSIBLE FOR THE 12Z TAFS. MAIN
CONCERNS WILL BE THE DURATION OF THE MVFR VIS WITH THE LIGHT SNOW
FOR KGLD AND IF THE CEILINGS BE MVFR OR LOW VFR DURING THE DAY.
LATEST OBSERVATIONS UP STREAM OVER NORTHEAST COLORADO AND EXTREME NORTHWEST
KANSAS HAVE MVFR TO LOW VFR VIS AND VFR CEILINGS. THE SNOWFALL
WILL CONTINUE TO TAPER OFF THROUGH THE MORNING...SO THE VIS SHOULD
CONTINUE TO IMPROVE. DESPITE MODELS PLACING KGLD UNDER MVFR
CEILINGS THROUGH THE DAY AM THINKING THE CEILINGS WILL BE LOW VFR
INSTEAD...KEYING OFF OF THE OBSERVATIONS OF LOWEST CEILINGS BEING
VFR EVEN IN THE LIGHT SNOWFALL. HRRR HAS LOW MVFR CEILINGS MOVING
IN DURING THE AFTERNOON AS THE SURFACE HIGH OVER NEBRASKA MOVES
SOUTH INTO KANSAS. WITH WARMER TEMPERATURES AND THE ENVIRONMENT
DRYING OUT THROUGH THE DAY...WILL KEEP WITH THE LOW VFR CEILINGS
BUT WILL ADJUST IF NEEDED. OVERNIGHT FREEZING FOG AND LOW STRATUS
ARE POSSIBLE FOR KGLD.
KMCK WILL REMAIN IN THE DRIER AIR TODAY. AS SUCH CONDITIONS WILL
BE VFR WITH LIGHT WINDS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
KS...NONE.
NE...NONE.
&&
$$
SHORT TERM...JRM
LONG TERM....JTL
AVIATION...JTL
AREA FORECAST DISCUSSION
NWS GOODLAND KS
942 PM MST FRI FEB 10 2012
.UPDATE...
600 PM MST FRI FEB 10 2012
STARTING GET A NICE NW-SE NARROW BAND OF SNOW FROM YUMA COUNTY
THROUGH SAINT FRANCIS TOWARD COLBY IN GOOD 700 FRONTOGENESIS FROM
GFS AND MID TO RIGHT REAR PORTION OF UPPER JET. YUMA WEB-CAM
SHOWING ROADS COVERED WITH PROBABLY AN INCH OR SO ALREADY ON THE
GROUND.
HAVE BUMPED UP SNOWFALL AMOUNTS SLIGHTLY...ESPECIALLY THROUGH 06Z
GIVEN RADAR AND MODEL TRENDS. ALSO BUMPED UP POPS INTO THE LIKELY
TO CATEGORICAL RANGE WHERE CONFIDENCE HIGHEST THAT THE CURRENT
BAND OF SNOW IS AND IS EXPECTED TO BE THROUGH EARLY TONIGHT. AS
DRIER AIR MOVES IN FROM THE NORTH BETTER CHANCES OF SNOW WILL
SHIFT SOUTHWEST OF CURRENT POSITION.
WILL AWAIT 00Z DATA BEFORE ADDRESSING TEMPS AND WINDS BUT I DID
TWEAK DEWPOINTS DOWN BASED ON CURRENT OBS WHICH ARENT TOO FAR OFF
FROM MET/MAV GUIDANCE.
007
&&
.SYNOPSIS...
ISSUED AT 222 PM MST FRI FEB 10 2012
EARLY AFTERNOON WV IMAGERY AND RUC H5 ANALYSIS SHOW LARGE SCALE
TROUGH ACROSS SOUTHERN CANADA EXTENDING SOUTH ACROSS THE GREAT
LAKES AND NORTHERN PLAINS. AT THE SURFACE THE COLD FRONT THAT
PASSED THROUGH THE CWA THIS MORNING HAS STALLED ALONG THE W/SW
PART OF THE CWA.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 222 PM MST FRI FEB 10 2012
TONIGHT THROUGH EARLY SATURDAY...A FRONTAL BOUNDARY WILL REMAIN
NEARLY STATIONARY ACROSS THE HIGHER TERRAIN OF THE CENTRAL HIGH
PLAINS. EXPECT AREAS OF LIGHT SNOW TO DEVELOP OVERNIGHT IN THE
VICINITY OF THIS BOUNDARY AS WEAK WAVES MOVE THROUGH THE NORTHWEST
FLOW ALOFT. THERE IS A SLIGHT CHANCE OF SOME FREEZING FOG IN VERY
CLOSE PROXIMITY TO THE FRONT OVERNIGHT OVER FAR EASTERN COLORADO
WHERE THE LOW CLOUDS WILL INTERSECT THE TERRAIN. HAVE TRIMMED THE
AREAS OF FREEZING FOG DOWN SOME...BUT HAVE KEPT IT IN THERE. THE
AIRMASS BEGINS DRYING OUT OVERNIGHT AS THE COLD AIR CONTINUES TO
PUSH FURTHER INTO THE REGION...SO HAVE DECREASED PRECIPITATION AND
CLOUD COVER FROM NORTHEAST TO SOUTHWEST OVERNIGHT THROUGH EARLY
SATURDAY MORNING.
LOCKHART
SATURDAY THROUGH SATURDAY NIGHT...WITH BAROCLINIC ZONE AND
LINGERING H85-H7 FRONTOGENSIS ACROSS THE WESTERN CWA...CANT RULE
OUT CONTINUED LIGHT SNOW THROUGH MID AFTERNOON SATURDAY. AIRMASS
CONTINUES TO DRY OUT THROUGH MIDDAY FROM THE NORTHEAST...SO I HAVE
KEPT CHANCE MENTION LIMITED TO FAR WESTERN CWA THROUGH 21Z. WITH
LINGERING CLOUD COVER AND VERY COLD AIRMASS IN PLACE TEMPERATURES
WILL STRUGGLE TO WARM MUCH. CURRENT FORECAST ALLOWS FOR SOME
DIURNAL WARMING WITH TEMPS IN THE MID TEENS TO LOW 20S ACROSS MUCH
OF THE CWA...AND AROUND 12 NEAR MCCOOK. CONSIDERING THE COLD
AIRMASS ALOFT AND LINGERING LOW CLOUDS...THIS MAY BE TOO
OPTIMISTIC. MODEL SOUNDINGS STILL SHOWING WARM LAYER ABOVE H85
ACROSS THE WESTERN PARTS OF THE CWA SATURDAY NIGHT...WITH SHALLOW
COLD NEAR SATURATED LAYER BELOW THIS. WITH UPSLOPE STILL
PERSISTING ALONG BAROCLINIC ZONE IN EASTERN COLORADO CANT RULE
OUT FREEZING FOG OR FREEZING DRIZZLE THROUGH EARLY SUNDAY MORNING.
I SAW NO NEED TO MAKE ANY MAJOR CHANGES TO PREVIOUS FORECAST WHICH
ALREADY HAD AREAS OF FREEZING FOG/DRIZZLE SATURDAY NIGHT THROUGH
EARLY SUNDAY MORNING.
DR
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 222 PM MST FRI FEB 10 2012
SUNDAY THROUGH MONDAY...SHORTWAVE RIDGING SHOULD KEEP CONDITIONS
DRY DURING THE DAY SUNDAY...WITH TEMPERATURES MODERATING ALOFT
FROM THE WEST. LINGERING CLOUD COVER WILL STILL LIMIT THE AMOUNT
OF DIURNAL WARMING AT THE SURFACE...SO TEMPS WILL LIKELY STILL
REMAIN BELOW FREEZING IN THE E/NE HALF OF THE CWA. A SHORTWAVE
TROUGH WILL MOVE IN THE REGION BY SUNDAY NIGHT. THIS SYSTEM DOES
NOT APPEAR TO BE VERY WELL ORGANIZED WITH MAIN H25-H3 JET OVER
OKLAHOMA PANHANDLE. THERE STILL APPEARS TO BE ENOUGH LIFT/MOISTURE
THAT I CANT RULE OUT SNOW SUNDAY NIGHT THROUGH MONDAY MORNING. BY
MONDAY AFTERNOON SHORTWAVE RIDGING BUILDS BACK OVER CWA.
TUESDAY THROUGH FRIDAY...SPLIT FLOW DOMINATES THE PATTERN
THROUGH THE REMAINING EXTENDED PERIODS. WHILE GUIDANCE IN MODERATE
AGREEMENT ON THE OVERALL PATTER...THERE IS VERY POOR RUN TO RUN
CONSISTENCY IN REGARDS TO THE HANDLING OF SMALLER SCALE FEATURES.
BEST CHANCE FOR PRECIP STILL APPEARS TO BE TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT AS A SERIES OF SHORTWAVE TROUGHS MOVE THROUGH THE
PLAINS. POSITION/TIMING OF THESE FEATURES HAS BEEN ALL OVER THE
PLACE THE LAST FEW DAYS. THE 00Z ECMWF AND 00Z/12 GFS WERE
STARTING TO SHOW SIMILAR TRENDS FOR PRECIP OVER OUR CWA...WITH
LIGHT SNOW PREDOMINATELY OVER THE SOUTHERN HALF OF THE CWA QUICKLY
EXITING THE REGION BY TUESDAY AFTERNOON/WEDNESDAY NIGHT. THE 12Z
ECMWF AND GEM ARE BOTH MUCH MORE BULLISH WITH THIS SYSTEM
PRODUCING A CLOSED H5 CENTER AND MUCH MORE PRECIPITATION...WITH
THE 12Z ECMWF FURTHER NORTH AND LINGERS PRECIP THROUGH THURSDAY.
THIS IS SIGNIFICANT DEVIATION FROM PREVIOUS RUN AND ENSEMBLE DATA.
CONFIDENCE IS PRETTY LOW RIGHT NOW IN ANY PARTICULAR SOLUTION AT
THIS POINT CONSIDERING THE CHAOTIC NATURE OF THIS TYPE OF PATTER.
I KEPT THE FORECAST ON THE CONSERVATIVE END OF THE MODEL
SPREAD...WITH SLIGHT CHANCE POPS TUESDAY NIGHT THROUGH WEDNESDAY
NIGHT. TEMPERATURES THROUGH THIS PERIOD SHOULD REMAIN SLIGHTLY
BELOW NORMAL WITH HIGHS IN THE UPPER 30S/LOW 40S.
DR
&&
.AVIATION...
942 PM MST FRI FEB 10 2012
FOR THE 06Z TAFS...ONGOING ON AND OFF SNOW WILL CONTINUE TO
CONTRIBUTE TO BOUNCING CIGS/VIS BETWEEN LOW VFR AND IFR AT KGLD
WHICH WILL CONTINUE THROUGH THE OVERNIGHT HOURS. SNOW WILL
DECREASE TOWARDS 12Z AT WHICH TIME CONDITIONS WILL IMPROVE TO VFR WITH
A CLOUD DECK AROUND 5K FEET. AT KMCK...WITH DRYING OF THE LOW
LEVELS...HARD PRESSED TO SEE ANY SNOW WHICH WILL KEEP KMCK VFR
THROUGH THE PERIOD WITH MAINLY MID CLOUDS THROUGH THE PERIOD.
WINDS WILL SWITCH FROM THE NORTHEAST TO THE SOUTHEAST TOWARD
MIDDAY ON SATURDAY AS SURFACE HIGH PRESSURE MOVES TO THE EAST.
BAS
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1217 AM EST SAT FEB 11 2012
.Update...
Issued at 715 PM EST Feb 10 2012
Regional radars this evening show the first wave of precipitation
has all but exited the forecast area. Back to the west precipitation
has increased in coverage both ahead of and just behind the cold
front. Have decreased pops over the eastern portion of the forecast
area for the next few hours ahead of this next batch of snow. With a
bit of warmer air filtering in ahead of the front, there have been
some reports of sleet in southern Indiana and west central Kentucky,
so have included this in the grids for a few hours. However, a
change over to all snow is still expected. Updated grids have
already been sent. Products will be out soon.
.Short Term (Today and Tonight)...
Updated at 317 PM EST Feb 10 2012
First in a series of mid-level wave continues to push eastward into
the lower Ohio Valley this afternoon. Out ahead of this feature,
widespread precipitation shield has been affecting southern Indiana
and central Kentucky this afternoon. Colder thermal profiles across
the north have resulted in precipitation remaining in the form of
snow. However, across southern Kentucky, slightly warmer air aloft
has worked into that region which has resulted in a mix of rain
and/or just plain rain in areas down around Bowling Green and
Glasgow. This band of precipitation continues to head east and will
likely clear the I-65 corridor by 5PM EST and the Bluegrass region
by 7-8 PM tonight. Temperatures this afternoon have warmed into the
upper 30s in the west and with lower 30s in the east. Temperatures
have been taking a dip when the snow bands have moved through...then
have rebounded by a couple of degrees once the precipitation had
ended. For the remainder of the afternoon...we expect temperatures
to remain close to their current values and actually rise a degree
or two once the precipitation has ended as southerly flow attempts
to bring a little warmer air into the area ahead of the approaching
cold front to the northwest of the region. Snowfall accumulations
of a dusting or so will be possible with this afternoon snow
activity...but do not be surprised to see it melt rather quickly
once the precipitation ends. With temps expected to remain above
freezing this afternoon and this evening...am not anticipating much
in the way of travel problems for the afternoon rush and for evening
activities.
For Tonight, the next weather feature will be a strong cold front
that will surge through the region. Currently the front out to our
west near St. Louis. The front has been moving a bit slower than
the models had been forecasting an it is expected to hit our area a
little later than previously forecast. As the front approaches,
temperatures will likely rise slightly and we`ll see a return of
snow showers. The front looks to pass through the I-65 corridor
between 11P-12A EST tonight and then through the I-75 corridor by
2-3AM. Colder air will quickly rush in behind the front and
temperatures will fall into the lower 20s by sunrise on Saturday.
The latest HRRR, our local Hi-Res ARW WRF, and RUC data all show
snow shower activity occurring ahead and behind the front. Vertical
sounding profiles actually have a bit of a convective look to them
and I would not be surprised to see more of a snow shower/snow
squall type of activity to develop later tonight. In addition, the
pressure gradient will really tighten up and winds of 15-20 MPH with
gusts up to 30 MPH will be possible. These snow showers will be the
ones that bring the accumulating snow to the region. The snow
combined with temperatures falling into the lower 20s will result in
slick spots developing later tonight. Therefore we will leave the
current winter weather advisory intact...though much of the expected
snowfall and hazardous travel conditions will be delayed until later
tonight and into Saturday morning.
The front will continue to surge eastward on Saturday and
precipitation will end from west to east during the morning hours.
The models are trying to develop a fetch off of Lake Michigan.
However, the models have been often too aggressive with these during
this winter. Nonetheless...some snow shower activity looks to
persist into the morning hours on Saturday and that will likely add
a little more accumulation over in the Bluegrass region. Skies will
likely remain mostly cloudy through much of the day with
temperatures remaining in the 20s. Surface winds will remain
elevated during the day with winds of 10-20 MPH and gusts up to 25
MPH or so. This will keep wind chills down in the single digits at
times on Saturday.
As far as snowfall accumulations...the consensus guidance suggests
around an inch of accumulation for areas generally north of the WK
and BG Parkways. Little accumulation is expected in the far south
and southwest where a 1/2 inch or less will be possible. Highest
accumulations are going to be in the northeast generally east of
U.S. 27 where 1-2 inches of snowfall will be possible by the time
precipitation comes to an end on Saturday.
.Long Term (Saturday Night - Friday)...
Updated at 300 PM EST Feb 10 2012
1040mb high pressure will be over the central Plains Saturday night,
with an equally significant low off the New England coast. The
gradient in between will mean northwesterly winds that will just
start to weaken some as the night progresses. By the day Sunday, the
high will move to around Arkansas, making the strongest winds over
the Bluegrass and weaker across the southwest forecast area.
Temperatures will remain chilly however, with readings only getting
up to around freezing for highs. Wind chills Sunday morning again
look to be in the single digits for most of the area.
The next weather system to impact the region still looks to be
Monday night. Multiple waves within a strengthening southwesterly
flow will allow for precip all along the MS river valley Monday
afternoon and expect this moisture to advect east for the night.
Given forecast temperatures, expect at least a wintry mix for the
night, if not all snow for the north. By midnight, most of the
region should be into light to moderate snow. We could have another
advisory level event over southern Indiana with still some potential
over norther central Kentucky, but it is too early to be that
specific.
The difference with this system, compared to tonight`s snows, will
be that it looks to be followed by some warming for midweek. Models
are still not handling the longer term that well, so do not have
high confidence at this point. The 12Z GFS had a vortmax cross the
region Wednesday that was not in the previous forecast. the 00Z
ECMWF and now the 12Z have hinted at this as well, but there is not
much moisture associated with the impulse. Conversely, the system
that was expected for Thursday has now backed off as well in the 12Z
GFS, but the new ECMWF continues with a large storm system moving
into the midwest. Given such run-to-run inconsistency, will keep in
some precip chances each day, though with lower pops. Also, have
leaned more towards the precip type as rain, with highs into the 50s
Wednesday through Friday.
&&
.Aviation (06Z TAF Issuance)...
Updated at 0017 AM EST Feb 11 2012
Winds will increase abruptly from the northwest once a strong cold
front passes through each TAF site. Northwest winds will have
already arrived at SDF with winds averaging 15kt with gusts up to
25kt.
At BWG, expect a sharp wind shift to the northwest around 0530Z. At
LEX, winds will shift to the northwest around 08z. As this front
exits the region, blustery northwest winds will continue all the way
through 00z Sunday. with winds averaging 15 to 18kt and gusts up to
30kt at times around 18z.
Light snow showers and flurries will continue at SDF and BWG through
09z with visibilities remaining above 4sm within the heaviest
showers. After 09z, just flurries with VFR visibilities are
expected. Ceilings at BWG and SDF will rise to over 1k feet after
07z and stay within the MVFR range through 14z.
At LEX, light snow and snow showers will continue longer, through
12z with occasional high end IFR ceilings. Ceilings will rise
gradually after 14z at LEX into the MVFR range.
After 18z, broken clouds will scatter out at SDF and BWG, while
remaining broken to overcast in the MVFR range at LEX. Brisk
northwest winds will finally start to diminish to around 11kt around
00z Sunday.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL NOON EST /11 AM CST/ TODAY FOR
INZ076>079-083-084-089>092.
KY...WINTER WEATHER ADVISORY UNTIL NOON EST /11 AM CST/ TODAY FOR
KYZ023>043-045>049-053>057-061>067-070>078-081-082.
$$
Update...........EER
Short Term.......MJ
Long Term........RJS
Aviation.........JSD
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
554 PM EST SAT FEB 11 2012
.SYNOPSIS...
BLUSTERY NORTHWEST WINDS WILL MAINTAIN SNOW SHOWERS AND BLOWING
SNOW INTO EARLY SUNDAY MORNING, AND CAUSE SUBZERO WIND CHILL.
INCOMING MIDWEST HIGH PRESSURE WILL PROVIDE MODERATING TEMPERATURES
MONDAY AFTERNOON.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
WILL ALLOW ADVISORY FOR ZANESVILLE AREA TO EXPIRE AS MAIN BANDS OF
SNOW ARE EAST OF THAT REGION. MAIN BAND OF HEAVY SNOW CONTINUES
FROM COLUMBIANA COUNTY TO NEAR STEUBENVILLE AND SOUTH ACROSS
WASHINGTON COUNTY AND INTO THE RIDGES. THIS BAND HAS PRODUCED
RATES OVER AN INCH AN HOUR LAST 3-4 HOURS BUT IS BEGINNING TO
BREAK DOWN AS SHORTWAVE BEGINNING TO MOVE SOUTH ACROSS EASTERN
LAKES APPROACHES TO DISTURB FLOW. BANDS WILL CONTINUE ACROSS
GREATER PITTSBURGH REGION BEFORE DIMINISHING FOR A TIME LATE
EVENING AHEAD OF SHORTWAVE. PREVIOUS POPS SEEM IN LINE OVERALL.
PREVIOUS DISCUSSION FOLLOWS.
PER BLEND OF RECENT SURFACE AND RADAR DATA COUPLED WITH HRRR AND
NAM MODEL OUTPUT, EXPECT COLD BLUSTERY NORTHWEST WINDS TO PROVIDE
SNOW SHOWERS AND BLOWING SNOW FOR THE UPPER OHIO VALLEY EAST OF
THE OHIO LINE INTO EARLY SUNDAY MORNING. SO HAVE MAINTAINED THE
WINTER WEATHER HEADLINES.
WIND GUSTS ACROSS THE HIGHER MOUNTAINS CAN APPROACH 45 MPH,
ELSEWHERE 35-40 MPH. WITH TEMPERATURES IN THE TEENS, EXPECT WIND
CHILLS TO GO SUBZERO. ACROSS THE HIGHER MOUNTAINS, WIND CHILL CAN
GO TO MINUS 15, SO HAVE ADDED WIND CHILL ADVISORY THERE THROUGH
SUNDAY MORNING.
REGARDING SNOW SHOWER DETAILS, RECENT WRF-NMM AND HRRR SHOW THE
LAKE EFFECT SNOW BANDS SHIFTING SOUTH. ALSO NAM MODEL PROFILES
SHOW THE SUBSIDENCE INVERSION CAN LOWER, SO SNOW SHOWER INTENSITY
SHOULD DECREASE LATE TONIGHT. HOWEVER KEPT SNOW SHOWERS ACROSS THE
HIGHER ELEVATIONS, AS OROGRAPHIC INFLUENCES SOMETIMES MAINTAIN
SNOW SHOWERS LONGER THEN EXPECTED.
TEMPERATURE AND WIND DETAILS WERE BASED ON CONSENSUS OF GFS LAMP
AND NAM MODEL OUTPUT.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
RECENT NAM AND GFS MODEL OUTPUT SHOW HIGH PRESSURE PROVIDING DRY
CONDITIONS SUNDAY NIGHT INTO MONDAY NIGHT. TEMPERATURES WILL STILL
BE QUITE COLD INTO MONDAY MORNING, BUT THEN MODERATE TO WITHIN 5
DEGREES OF NORMAL MONDAY AFTERNOON.
MODELS THEN SHOW A WEAK LOW PRESSURE SYSTEM, COMING EAST FROM THE
PLAINS TO PROVIDE MIX OF SNOW AND RAIN SHOWERS TUESDAY, WITH
TEMPERATURES TUESDAY AFTERNOON NEAR NORMAL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
GENERALLY FOLLOWED EC AND HPC GUIDANCE. HIGH PRESSURE ACROSS REGION
WEDNESDAY WITH FAIR WEATHER. MODELS CONTINUE TO STRUGGLE WITH
STRENGTH OF LOW PRESSURE MOVING THROUGH OHIO RIVER VALLEY ON
THURSDAY...BUT EXPECT MOSTLY RAIN ON THURSDAY WITH SOME SNOW
POSSIBLE ACROSS FAR NORTH. BY FRIDAY SYSTEM IS WELL EAST OF AREA
WITH CHANCE OF SNOW SHOWERS IN NORTHWEST FLOW. HIGH PRESSURE
REMAINS WEST OF REGION WITH NORTHWEST FLOW. THIS SHOULD KEEP SOME
CLOUDINESS OF REGION...BUT LACK OF COLD AIR PRECLUDES SNOW SHOWER
ACTIVITY SATURDAY.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
COLD FRONT EAST OF CWA. THROUGH 12/00Z GENERAL CIGS 015-025 AND VSBY
2-4 MILES WITH CONDS LOWERING TO CIG 005 VSBY 3/4-1 MILE IN HEAVIER
SNOW BANDS.
MODELS SHOW SOME DRYING EARLY TONIGHT WITH ANOTHER BAND OF DEEPER
MOISTURE RETURNING AFTER MIDNIGHT. RAISED CONDITIONS TO MVFR AFTER
00Z THROUGH 06Z...THEN LOWERED TO IFR AFTER 07Z. LOWERING INVERSION
LAYER WILL CRUSH CONVECTION AFTER 15Z SUNDAY WITH CONDITIONS
BECOMING MVFR TO VFR.
OUTLOOK...MONDAY THROUGH THURSDAY...
BUILDING HIGH PRESSURE WILL RETURN BY MONDAY WITH VFR CONDITIONS.
SHORTWAVE IN ZONAL FLOW IS PROGGED TO GENERATE MORE LIGHT SNOW BY
EARLY TUESDAY. AT LEAST MVFR CAN BE EXPECTED WITH THAT SYSTEM.
REBUILDING HIGH PRESSURE WILL RETURN VFR BY LATE TUESDAY AND
WEDNESDAY.
STRONGER SYSTEM MOVES THROUGH REGION ON THURSDAY WITH LOW PASSING
WEST OF CWA. RAIN REACHING WESTERN TERMINALS THURSDAY MORNING AND
SPREADING ACROSS REGION BY AFTERNOON. CONDITIONS DETERIORATING TO
MVFR IN MOSTLY RAIN. SOME SNOW OR RAIN AND SNOW POSSIBLE AT NORTHERN
TERMINALS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR MDZ001.
WIND CHILL ADVISORY UNTIL NOON EST SUNDAY FOR MDZ001.
OH...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR OHZ039-
048-057-058-068.
WINTER WEATHER ADVISORY UNTIL 6 AM EST SUNDAY FOR OHZ040-041-
049-050-059-069.
PA...WINTER WEATHER ADVISORY UNTIL 6 AM EST SUNDAY FOR PAZ007>009-
013>016-020>023-029-031-073-075.
WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR PAZ074-076.
WIND CHILL ADVISORY UNTIL NOON EST SUNDAY FOR PAZ074-076.
WV...WINTER WEATHER ADVISORY UNTIL 6 AM EST SUNDAY FOR WVZ001>004-
012-021-022.
WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR WVZ023-041.
WIND CHILL ADVISORY UNTIL NOON EST SUNDAY FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
359 PM EST SAT FEB 11 2012
.SYNOPSIS...
BLUSTERY NORTHWEST WINDS WILL MAINTAIN SNOW SHOWERS AND BLOWING
SNOW INTO EARLY SUNDAY MORNING, AND CAUSE SUBZERO WIND CHILL.
INCOMING MIDWEST HIGH PRESSURE WILL PROVIDE MODERATING TEMPERATURE
MONDAY AFTERNOON.
&&
.NEAR TERM /UNTIL 6 PM SUNDAY/...
PER BLEND OF RECENT SURFACE AND RADAR DATA COUPLED WITH HRRR AND
NAM MODEL OUTPUT, EXPECT COLD BLUSTERY NORTHWEST WINDS TO PROVIDE
SNOW SHOWERS AND BLOWING SNOW FOR THE UPPER OHIO VALLEY EAST OF
THE OHIO LINE INTO EARLY SUNDAY MORNING. SO HAVE MAINTAINED THE
WINTER WEATHER HEADLINES.
WIND GUSTS ACROSS THE HIGHER MOUNTAINS CAN APPROACH 45 MPH,
ELSEWHERE 35-40 MPH. WITH TEMPERATURES IN THE TEENS, EXPECT WIND
CHILLS TO GO SUBZERO. ACROSS THE HIGHER MOUNTAINS, WIND CHILL CAN
GO TO MINUS 15, SO HAVE ADDED WIND CHILL ADVISORY THERE THROUGH
SUNDAY MORNING.
REGARDING SNOW SHOWER DETAILS, RECENT WRF-NMM AND HRRR SHOW THE
LAKE EFFECT SNOW BANDS SHIFTING SOUTH. ALSO NAM MODEL PROFILES
SHOW THE SUBSIDENCE INVERSION CAN LOWER, SO SNOW SHOWER INTENSITY
SHOULD DECREASE LATE TONIGHT. HOWEVER KEPT SNOW SHOWERS ACROSS THE
HIGHER ELEVATIONS, AS OROGRAPHIC INFLUENCES SOMETIMES MAINTAIN
SNOW SHOWERS LONGER THEN EXPECTED.
TEMPERATURE AND WIND DETAILS WERE BASED ON CONSENSUS OF GFS LAMP
AND NAM MODEL OUTPUT.
&&
.SHORT TERM /SUNDAY EVENING THROUGH TUESDAY/...
RECENT NAM AND GFS MODEL OUTPUT SHOW HIGH PRESSURE PROVIDING DRY
CONDITIONS SUNDAY NIGHT INTO MONDAY NIGHT. TEMPERATURES WILL STILL
BE QUITE COLD INTO MONDAY MORNING, BUT THEN MODERATE TO WITHIN 5
DEGREES OF NORMAL MONDAY AFTERNOON.
MODELS THEN SHOW A WEAK LOW PRESSURE SYSTEM, COMING EAST FROM THE
PLAINS TO PROVIDE MIX OF SNOW AND RAIN SHOWERS TUESDAY, WITH
TEMPERATURES TUESDAY AFTERNOON NEAR NORMAL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
GENERALLY FOLLOWED EC AND HPC GUIDANCE. HIGH PRESSURE ACROSS REGION
WEDNESDAY WITH FAIR WEATHER. MODELS CONTINUE TO STRUGGLE WITH
STRENGTH OF LOW PRESSURE MOVING THROUGH OHIO RIVER VALLEY ON
THURSDAY...BUT EXPECT MOSTLY RAIN ON THURSDAY WITH SOME SNOW
POSSIBLE ACROSS FAR NORTH. BY FRIDAY SYSTEM IS WELL EAST OF AREA
WITH CHANCE OF SNOW SHOWERS IN NORTHWEST FLOW. HIGH PRESSURE
REMAINS WEST OF REGION WITH NORTHWEST FLOW. THIS SHOULD KEEP SOME
CLOUDINESS OF REGION...BUT LACK OF COLD AIR PRECLUDES SNOW SHOWER
ACTIVITY SATURDAY.
&&
.AVIATION /21Z SATURDAY THROUGH THURSDAY/...
COLD FRONT EAST OF CWA. THROUGH 12/00Z GENERAL CIGS 015-025 AND VSBY
2-4 MILES WITH CONDS LOWERING TO CIG 005 VSBY 3/4-1 MILE IN HEAVIER
SNOW BANDS.
MODELS SHOW SOME DRYING EARLY TONIGHT WITH ANOTHER BAND OF DEEPER
MOISTURE RETURNING AFTER MIDNIGHT. RAISED CONDITIONS TO MVFR AFTER
00Z THROUGH 06Z...THEN LOWERED TO IFR AFTER 07Z. LOWERING INVERSION
LAYER WILL CRUSH CONVECTION AFTER 15Z SUNDAY WITH CONDITIONS
BECOMING MVFR TO VFR.
OUTLOOK...MONDAY THROUGH THURSDAY...
BUILDING HIGH PRESSURE WILL RETURN BY MONDAY WITH VFR CONDITIONS.
SHORTWAVE IN ZONAL FLOW IS PROGGED TO GENERATE MORE LIGHT SNOW BY
EARLY TUESDAY. AT LEAST MVFR CAN BE EXPECTED WITH THAT SYSTEM.
REBUILDING HIGH PRESSURE WILL RETURN VFR BY LATE TUESDAY AND
WEDNESDAY.
STRONGER SYSTEM MOVES THROUGH REGION ON THURSDAY WITH LOW PASSING
WEST OF CWA. RAIN REACHING WESTERN TERMINALS THURSDAY MORNING AND
SPREADING ACROSS REGION BY AFTERNOON. CONDITIONS DETERIORATING TO
MVFR IN MOSTLY RAIN. SOME SNOW OR RAIN AND SNOW POSSIBLE AT NORTHERN
TERMINALS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR MDZ001.
WIND CHILL ADVISORY UNTIL NOON EST SUNDAY FOR MDZ001.
OH...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR OHZ039-
048-057-058-068.
WINTER WEATHER ADVISORY UNTIL 6 AM EST SUNDAY FOR OHZ040-041-
049-050-059-069.
PA...WINTER WEATHER ADVISORY UNTIL 6 AM EST SUNDAY FOR PAZ007>009-
013>016-020>023-029-031-073-075.
WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR PAZ074-076.
WIND CHILL ADVISORY UNTIL NOON EST SUNDAY FOR PAZ074-076.
WV...WINTER WEATHER ADVISORY UNTIL 6 AM EST SUNDAY FOR WVZ001>004-
012-021-022.
WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR WVZ023-041.
WIND CHILL ADVISORY UNTIL NOON EST SUNDAY FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
947 AM EST SAT FEB 11 2012
.SYNOPSIS...
THE ARCTIC COLD FRONT WILL HAVE EXITED EAST PAST THE MOUNTAINS BY
MIDDAY. IN ITS WAKE, EXPECT SNOW SHOWERS, GUSTY WINDS,
TEMPERATURES IN THE TEENS WITH WIND CHILL GOING SUBZERO TONIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
PER BLEND OF RECENT SURFACE AND RADAR DATA COUPLED WITH HRRR AND
NAM MODEL OUTPUT, EXPECT THE ARCTIC COLD FRONT TO HAVE EXITED EAST
PAST THE MOUNTAINS BY NOON. IN ITS WAKE, BANDS OF LAKE-ENHANCED SNOW
SHOWERS WILL CONTINUE INTO TONIGHT. NORTHWEST WINDS CAN GUST OVER
35 MPH...UP TO 45 MPH ACROSS THE HIGHER ELEVATIONS.
TEMPERATURES WILL BE IN THE TEENS ALL LOCATIONS BY MID AFTERNOON,
IF NOT SOONER. WIND CHILLS WILL BE IN THE SINGLE DIGITS, GOING
SUBZERO TONIGHT. WIND CHILLS ACROSS THE WV-MD MOUNTAINS MAY GO TO
MINUS 10.
AT THIS JUNCTURE, HAVE MAINTAINED CURRENT FORECAST OF SNOW
AMOUNTS. THESE WILL BE QUITE VARIABLE DUE TO SNOW BANDING. IN
GENERAL, MOST LOCATIONS CAN EXPECT 1 OR 2 INCHES THIS AFTERNOON.
HIGHER ELEVATIONS AND POINTS NORTH UP TO 4 INCHES.
TONIGHT, MOST LOCATIONS WILL ADD AN INCH OF SNOW, BUT NORTH AND
MOUNTAINS, UP TO 4 INCHES.
NAM MODEL PROFILES CONTINUE TO SHOW A LOWERING SUBSIDENCE
INVERSION LATE TONIGHT, WHICH WILL CAP THE INSTABILITY, AND WEAKEN
SNOW SHOWERS WEST OF THE MOUNTAINS BY MIDNIGHT, AND OVER THE
MOUNTAINS EARLY SUNDAY MORNING.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY/...
FLOW CONTINUING OFF LAKE ERIE WILL ALLOW FOR LAKE ENHANCED SNOW
SHOWERS TO CONTINUE. LOW INVERSION LEVELS WILL CONTINUE TO KEEP
ACCUMULATIONS IN CHECK...WITH ONLY AN INCH OR SO EXPECTED. CONTINUED
STRONG WINDS WILL BRING ANOTHER DAY OF GUSTY WINDS...AND CANNOT RULE
OUT THE POSSIBILITY THAT A WIND ADVISORY MAY BE NEEDED IN THE HIGHER
ELEVATIONS ON SUNDAY. HIGH PRESSURE WILL MOVE IN FROM THE SOUTHWEST
SUNDAY NIGHT. THIS WILL SHIFT THE WIND DIRECTION OFF LAKE
ERIE...BRINGING AN END TO ALL SNOW SHOWERS.
EXPECT DRY CONDITIONS ON MONDAY WITH HIGH PRESSURE IN THE
VICINITY. CLOUDS WILL BE ON THE INCREASE MONDAY NIGHT AS AN UPPER
LEVEL TROUGH APPROACHES FROM THE WEST. BUMPED UP POPS TO HIGH
CHANCE ON TUESDAY WITH THE APPROACH OF THE TROUGH. TEMPERATURES
WILL SLOWLY MODERATE...BUT WILL REMAIN BELOW NORMAL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
THERE IS CONSIDERABLE DISAGREEMENT IN OPERATION MODEL SOLUTIONS,
SO FORECAST SIDES CLOSEST TO THE HPC/ECMWF SOLUTION. THUS, LOW
CONFIDENCE FORECAST HAS A FAST- MOVING CLOSED LOW MOVING ACROSS
THE AREA AND BRINGING THE CHANCE OF SNOW ON THURSDAY, FOLLOWED BY
HIGH PRESSURE DRYING OUT THE FORECAST FOR THE END OF THE WEEK.
TEMPERATURES ON WEDNESDAY WILL MODERATE TO NEAR NORMAL VALUES AND
CONTINUE TO WARM TO 5 DEGREES ABOVE NORMAL FOR THURSDAY AND
FRIDAY.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
CDFNT WL COMPLETE A SWEEP OF THE UPR OH REGION THIS MRNG WITH IFR
CONDITIONS IN -SN CONTG.
AS THE CDFNT PUSHES EWD BY THIS AFTERNOON...NW FLOW WL MAINTAIN RESTRICTIONS
IN -SHSN AND REDUCED CIGS. WIND GUSTS OF 30 TO 35KTS WL ALSO
HAMPER AVIATION. DRY ADVCTN AND GRADUALLY LOWERING INVERSION WL
IMPROVE CONDITIONS TONIGHT...BUT MVFR SC AND AT CONTG SCT -SHSN
SHOULD BE ANTICIPATED.
OUTLOOK...SUNDAY THROUGH WEDNESDAY...
COLD NWLY FLOW WL SUPPORT MVFR...TO BARELY VFR SC ON SUNDAY...BUT
BUILDING HIGH PRES SHOULD RTN PREDOMINATE VFR BY MONDAY.
SHORTWV IN ZONAL FLOW IS PROGGED TO GENERATE MORE -SN FOR MONDAY NGT
AND EARLY TUESDAY. TIMING WL HAVE TO BE MONITORED WITH THAT
PROGRESSIVE SYSTEM...BUT AT LEAST MVFR CAN BE EXPECTED WITH THAT
SYSTEM. REBUILDING HIGH PRES WOULD THEN RTN VFR BY LATE TUESDAY AND
WEDNESDAY WITH THIS SCENARIO.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR MDZ001.
OH...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR OHZ039-
048-057-058-068.
WINTER WEATHER ADVISORY UNTIL 6 AM EST SUNDAY FOR OHZ040-041-
049-050-059-069.
PA...WINTER WEATHER ADVISORY UNTIL 6 AM EST SUNDAY FOR PAZ007>009-
013>016-020>023-029-031-073-075.
WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR PAZ074-076.
WV...WINTER WEATHER ADVISORY UNTIL 6 AM EST SUNDAY FOR WVZ001>004-
012-021-022.
WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
124 PM EST SAT FEB 11 2012
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 446 AM EST SAT FEB 11 2012
LATEST WV IMAGERY AND RUC ANALYSIS REVEALS THE CENTER OF THE POLAR
VORTEX EAST OF HUDSON BAY WITH A MID/UPPER LEVEL TROUGH AXIS
EXTENDING SOUTH INTO THE CENTRAL GREAT LAKES. AT THE SFC...A 1044 MB
ARCTIC HIGH WAS CENTERED OVER THE DAKOTAS. RADAR IMAGERY AND SFC OBS
SHOW WIND PARALLEL LES BANDS FROM EAST OF MQT TO GRAND MARAIS BEING
SUPPORTED BY ENHANCED LOW-LVL CONVERGENCE FROM NW WIND FLOW ACROSS
MUCH OF LAKE SUPERIOR AND THEN LAND BREEZE CIRCULATION OFF OF
ONTARIO CAUSING A NE WIND OVER FAR ERN LAKE SUPERIOR. LES BANDS WITH
RETURNS TO 30 DBZ ARE FAIRLY WELL SPACED APART DUE TO VERY DRY
UPSTREAM AND LARGE SCALE ANTICYCLONIC FLOW ACROSS THE AREA. SURGE OF
MID TO LOW-LVL MOISTURE IN WAA PATTERN MOVING IN FROM NORTH OF LAKE
SUPERIOR IS SHOWING SIGNS OF ENHANCING LES BANDS ACROSS THE LAKE IN
THE PAST HR OR SO. THIS WILL BE SOMETHING TO MONITOR AS THE DAY
PROGRESSES TO SEE IF IT WILL BOOST LES ACCUMS DOWNWIND OF THE LAKE.
TODAY...AS 850-700 MB MOISTURE INCREASES IN A DEVELOPING WAA PATTERN
THERE COULD BE A BRIEF INCREASE IN LES INTENSITY FOR THE ERN
COUNTIES FAVORED BY A WNW/NW WIND. AS I SAID...BELIEVE ANY FLARE UP
IN LES WILL BE SHORT-LIVED SINCE WAA AND RISING 850 MB TEMPS WILL
EVENTUALLY FORCE THE DGZ ABV THE BEST OMEGA/UPWARD MOTION WITHIN THE
CONVECTIVE BOUNDARY LAYER BY THE LATE AFTERNOON/EVENING HRS. LONGER
FETCH ACROSS THE LAKE ALONG WITH MORE FAVORABLE LES PARAMETERS
SUGGEST BEST SNOW ACCUMULATIONS WILL BE OVER THE NE FCST
AREA...WHERE AMOUNTS IN THE 2 TO 4 INCH RANGE ARE POSSIBLE...JUST
BLO ADVISORY CRITERIA. ELSEWHERE...NEAR LAKE SUPERIOR EXPECT LES
AMTS GENERALLY 2 INCHES OR LESS.
TONIGHT...TROF ASSOCIATED WITH POLAR VORTEX E OF HUDSON BAY WILL
BEGIN SHIFTING E OF THE REGION...ALLOWING FOR PROMINENT RIDGING AND
WAA REGIME TO SET UP AND CONTINUE INTO SUN. LES WILL BE ONGOING SAT
EVENING OVER THE E AT LOCATIONS FAVORED BY A WNW/NW WIND OFF LAKE
SUPERIOR. HOWEVER...INVERSION QUICKLY SETTLES DOWN TO 4KFT OR LWR BY
LATE EVENING AND OVERNIGHT. ALSO...CONTINUED WAA WILL KEEP THE
DENDRITIC SNOW GROWTH TEMP ZONE (DGZ) UP ABOVE BEST UPWARD MOTION.
IN GENERAL...MIGHT SEE ANOTHER 1-2...POSSIBLY UP TO 3 INCHES OF SNOW
OVER THE NE FCST AREA SAT NIGHT. OUT W...INVERSION WILL ALREADY BE
SETTLING TO 3KFT OR LWR EARLY IN THE EVENING WITH DGZ ABOVE THE
INVERSION. GIVEN THE LOW INVERSION AND MODERATING AIRMASS...THERE
MAY NOT BE MUCH LEFT OTHER THAN FLURRIES THIS EVENING WITH GRADUAL
CLEARING THEN FOLLOWING DURING THE NIGHT FROM THE W. WITH
CLEARING...MINS COULD DROP NEAR ZERO IN THE TRADITIONAL COLD SPOTS
OVER THE INTERIOR W HALF. NEAR LAKE SUPERIOR WHERE THERE WILL BE
BETTER MIXING AND MODERATION FROM ONSHORE NW FLOW TO KEEP MIN TEMPS
IN THE TEENS.
SUNDAY...LINGERING LIGHT LES/FLURRIES OVER THE NE FCST AREA WILL END
IN THE MORNING AS THE INVERSION CONTINUES TO LWR AND MORE
IMPORTANTLY TEMPS AT INVERSION BASE RISE ABOVE -10C. AWAY FROM
DIMINISHING LIGHT LES E...IT SHOULD TURN OUT TO BE A MAINLY SUNNY
DAY UNDER A DEEP DRY AIR MASS. DRY AIR MASS AND SUNSHINE WORKING ON
THE LWR ALBEDO FORESTED LANDSCAPE OF UPPER MI WILL ASSIST THE WARM
UP...BUT STRONG INVERSION WILL HOLD BACK THE WARMING POTENTIAL OVER
WHAT IT COULD BE. FCST SOUNDINGS SUGGEST MIXING TO JUST ABV 925 MB
LOOK FOR HIGHS GENERALLY IN THE MID/UPPER 20S.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 446 AM EST SAT FEB 11 2012
UPPER TROUGH WILL BE ROTATING E OF THE AREA AT THE START OF THE LONG
TERM PERIOD...LEADING TO THE AREA BEING BETWEEN THE SPLIT FLOW OF
THE NRN STREAM RIDGE OVER THE CANADIAN PRAIRIES AND THE SRN STREAM
RUNNING ACROSS THE SRN FOURTH OF THE CONUS. THIS WILL KEEP THE AREA
UNDER QUIET WEATHER TO START THE PERIOD WITH A HIGH PRESSURE RIDGE
PUSHING OVER THE WRN CWA SUN NIGHT AND MON...WHILE BROAD H850-700
WAA INTENSIFIES OVER STATIONARY FRONT OVER SE ONTARIO.
SUN NIGHT...EXPECT A MOSTLY CLEAR NIGHT WITH THE HIGH PRESSURE RIDGE
PUSHING OVER THE AREA. LOWS WILL DEPEND ON HOW QUICKLY WINDS CAN
DECOUPLE ON MON NIGHT...AS GRADIENT BETWEEN STATIONARY FRONT AND
APPROACHING SFC RIDGE TRIES TO KEEP WINDS UP. BEST CHANCE FOR LIGHT
WINDS WILL BE CLOSER TO THE SFC RIDGE OVER THE SW HALF OF THE
CWA...WHERE PWAT VALUES FALL TO 40 PERCENT OF NORMAL. HAVE TRENDED
TOWARDS THE LOW END OF GUIDANCE...BUT NOT QUITE AS COLD AS IF THE
WAS HIGHER CONF FOR LIGHT WINDS.
MON...AREA WILL BE BETWEEN SFC TROUGH IN SE ONTARIO AND H500
SHORTWAVE AND ASSOCIATED HEIGHT FALLS MOVING THROUGH THE MID MISS
VALLEY AND APPROACHING THE LOWER GREAT LKS MON NIGHT. EXPECT A
MOSTLY SUNNY DAY FOR MUCH OF THE AREA...ALTHOUGH CLOUDS WILL ATTEMPT
TO PUSH ACROSS THE WI BORDER LATE IN THE AFTN WITH MOISTURE
INCREASING AHEAD OF THE SHORTWAVE. HIGHS WILL DEPEND ON AMNT OF
MIXING. MODELS INDICATING MIXING UP TO H900...WHICH WOULD PRODUCE
HIGHS OF 30-35. WITH ABUNDANT SUNSHINE TO START THE DAY...FELT TEMPS
WILL WARM UP QUICKLY AND ONLY MADE A DEGREE OR TWO ADJUSTMENT UP TO
GOING HIGHS.
MODELS CONSISTENT IN H850-650 MOISTURE MOVING INTO THE SRN HALF OF
THE AREA MON NIGHT AS THE SHORTWAVE MOVES SOUTH OF THE CWA. BUT WITH
LACK OF ISENTROPIC ASCENT...WAA...AND MAIN FORCING S OF THE CWA WITH
H500 HEIGHT FALLS...THINK PCPN CHANCES ARE FAIRLY LIMITED.
THEREFORE...HAVE JUST A SLIGHT CHANCE OVER THE SCNTRL CWA AND
CHANCES BRUSHING THE CITY OF MENOMINEE.
DAYS 4 THROUGH 7 /TUES THROUGH FRIDAY/...
SRN STREAM TROUGH WILL BEGIN TO DIG OVER THE SW CONUS ON
TUES...ALLOWING RIDGING TO DEVELOP OVER THE SRN/CNTRL PLAINS AND
CONTINUE INTO WED. MEANWHILE...TROUGH WILL START TO AMPLIFY OVER THE
CANADIAN ROCKIES IN THE NRN STREAM ON TUES AND ATTEMPT TO MERGE WITH
THE SRN STREAM WED NIGHT INTO THURS. THESE SITUATIONS TEND TO BE
DIFFICULT FOR MODELS...BUT 00Z GFS/ECMWF/GEM AND ASSOCIATED ENS
MEANS HANDLE THE LARGE SCALE FEATURES SIMILARLY BUT DO HAVE
DIFFICULTY WITH THE EMBEDDED SHORTWAVES. THUS...HAVE AVERAGE CONF
FOR MUCH OF THE EXTENDED PERIOD.
INITIAL SYSTEM EXITS THE AREA ON TUES...LEAVING AREA IN WSWRLY LLVL
FLOW AND H850 TEMPS AROUND -8C. THIS PROVIDES LIMITED POTENTIAL FOR
LES AND WILL LIKELY SEE MOSTLY CLOUDY SKIES LINGERING INTO WED WITH
NEXT POTENTIAL SHORTWAVE MOVING THROUGH...ALTHOUGH MODELS HAVE LARGE
DIFFERENCES IN INTENSITY.
NRN/SRN STREAMS LOOK TO PHASE ON THURS. WITH THE MORE DOMINATE SRN
STREAM...EXPECT SFC LOW DEVELOPMENT TO FOLLOW THE SRN STREAM TRACK
THAT WILL LIKELY TAKE IT THROUGH THE OHIO VALLEY OR LOWER GREAT LKS.
THIS WOULD BRUSH THE SE CWA AS BEST FORCING/MOISTURE REMAINS CLOSER
TO THE LOW. 00Z ECMWF DID TREND A LITTLE FARTHER NW WITH THE TRACK
OF THE LOW...SO WILL NEED TO WATCH ON FUTURE SHIFTS.
MODELS BEGIN TO DIVERGE HEADING INTO FRI WITH THE HANDLING OF THE
NRN STREAM FEATURES AND WHERE THE SRN STREAM UPPER TROUGH IS LOCATED
OVER THE SW CONUS. H850 TEMPS AROUND -11C WOULD LEAD TO SOME LES
POTENTIAL UNDER NW WINDS...BUT LLVL MOISTURE OVER THE W MAY BE
LIMITED. THEREFORE...ONLY MENTIONED CHANCE POPS OVER THE ERN AREAS
FAVORED BY NW WINDS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 123 PM EST SAT FEB 11 2012
POCKETS OF CLEARING HAVE DEVELOPED IN THE MORE NW FLOW OFF LAKE
SUPERIOR...AT BOTH IWD AND SAW. THE RESULT IS TEMPORARY SCATTERED
CLOUDS...WHICH CMX REMAINS STUCK IN THE MVFR CEILINGS WITH VIS
DROPPING TO LIFR AT TIMES. THE DEEPER MOISTURE OVER THE LAKE WILL
SLOWLY WEAKEN OVERNIGHT..ALTHROUGH NW WINDS WILL STAY WITH GUSTS IN
THE 20 TO 30KT RANGE OVER THE ENTIRE PERIOD. LLWS WILL LIKELY
DEVELOP AT SAW...GIVEN THE NW WIND DIRECTION DURING THE LATE
EVENING/OVERNIGHT HOURS. OTHERWISE...VFR CEILINGS AND VIS WILL TAKE
HOLD AT ALL 3 SITES BY 06Z SUNDAY AS A RIDGE OF HIGH PRESSURE SLIDES
ACROSS THE REGION.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 446 AM EST SAT FEB 11 2012
NNW WINDS TO 30KT WILL PERSIST WITH AMPLE INSTABILITY IN THE ARCTIC
AIRMASS MOVING OVER THE REGION. NW WINDS APPROACHING GALES TO 35 KT
ARE ALSO POSSIBLE THIS AFTERNOON INTO THIS EVENING OVER ERN LAKE
SUPERIOR. EXPECT HEAVY FREEZING SPRAY ACROSS THE ENTIRE LAKE THROUGH
TONIGHT WITH THE STRONG WINDS AND WAVE ACTION. LOOK FOR HEAVY
FREEZING SPRAY TO END ON SUNDAY AS THE AIRMASS WARMS AND WINDS
GRADUALLY DIMINISH. CONDITIONS WILL QUIET DOWN FOR THE EARLY PART OF
THE WORK WEEK AS A HIGH PRES RIDGE MOVES OVER THE UPPER GREAT LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ SUNDAY
FOR LSZ162-240>251-263>267.
GALE WARNING FROM 5 PM THIS AFTERNOON TO 3 AM EST SUNDAY FOR
LSZ248>250-265-266.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...SRF
AVIATION...KF
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
832 AM EST SAT FEB 11 2012
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 446 AM EST SAT FEB 11 2012
LATEST WV IMAGERY AND RUC ANALYSIS REVEALS THE CENTER OF THE POLAR
VORTEX EAST OF HUDSON BAY WITH A MID/UPPER LEVEL TROUGH AXIS
EXTENDING SOUTH INTO THE CENTRAL GREAT LAKES. AT THE SFC...A 1044 MB
ARCTIC HIGH WAS CENTERED OVER THE DAKOTAS. RADAR IMAGERY AND SFC OBS
SHOW WIND PARALLEL LES BANDS FROM EAST OF MQT TO GRAND MARAIS BEING
SUPPORTED BY ENHANCED LOW-LVL CONVERGENCE FROM NW WIND FLOW ACROSS
MUCH OF LAKE SUPERIOR AND THEN LAND BREEZE CIRCULATION OFF OF
ONTARIO CAUSING A NE WIND OVER FAR ERN LAKE SUPERIOR. LES BANDS WITH
RETURNS TO 30 DBZ ARE FAIRLY WELL SPACED APART DUE TO VERY DRY
UPSTREAM AND LARGE SCALE ANTICYCLONIC FLOW ACROSS THE AREA. SURGE OF
MID TO LOW-LVL MOISTURE IN WAA PATTERN MOVING IN FROM NORTH OF LAKE
SUPERIOR IS SHOWING SIGNS OF ENHANCING LES BANDS ACROSS THE LAKE IN
THE PAST HR OR SO. THIS WILL BE SOMETHING TO MONITOR AS THE DAY
PROGRESSES TO SEE IF IT WILL BOOST LES ACCUMS DOWNWIND OF THE LAKE.
TODAY...AS 850-700 MB MOISTURE INCREASES IN A DEVELOPING WAA PATTERN
THERE COULD BE A BRIEF INCREASE IN LES INTENSITY FOR THE ERN
COUNTIES FAVORED BY A WNW/NW WIND. AS I SAID...BELIEVE ANY FLARE UP
IN LES WILL BE SHORT-LIVED SINCE WAA AND RISING 850 MB TEMPS WILL
EVENTUALLY FORCE THE DGZ ABV THE BEST OMEGA/UPWARD MOTION WITHIN THE
CONVECTIVE BOUNDARY LAYER BY THE LATE AFTERNOON/EVENING HRS. LONGER
FETCH ACROSS THE LAKE ALONG WITH MORE FAVORABLE LES PARAMETERS
SUGGEST BEST SNOW ACCUMULATIONS WILL BE OVER THE NE FCST
AREA...WHERE AMOUNTS IN THE 2 TO 4 INCH RANGE ARE POSSIBLE...JUST
BLO ADVISORY CRITERIA. ELSEWHERE...NEAR LAKE SUPERIOR EXPECT LES
AMTS GENERALLY 2 INCHES OR LESS.
TONIGHT...TROF ASSOCIATED WITH POLAR VORTEX E OF HUDSON BAY WILL
BEGIN SHIFTING E OF THE REGION...ALLOWING FOR PROMINENT RIDGING AND
WAA REGIME TO SET UP AND CONTINUE INTO SUN. LES WILL BE ONGOING SAT
EVENING OVER THE E AT LOCATIONS FAVORED BY A WNW/NW WIND OFF LAKE
SUPERIOR. HOWEVER...INVERSION QUICKLY SETTLES DOWN TO 4KFT OR LWR BY
LATE EVENING AND OVERNIGHT. ALSO...CONTINUED WAA WILL KEEP THE
DENDRITIC SNOW GROWTH TEMP ZONE (DGZ) UP ABOVE BEST UPWARD MOTION.
IN GENERAL...MIGHT SEE ANOTHER 1-2...POSSIBLY UP TO 3 INCHES OF SNOW
OVER THE NE FCST AREA SAT NIGHT. OUT W...INVERSION WILL ALREADY BE
SETTLING TO 3KFT OR LWR EARLY IN THE EVENING WITH DGZ ABOVE THE
INVERSION. GIVEN THE LOW INVERSION AND MODERATING AIRMASS...THERE
MAY NOT BE MUCH LEFT OTHER THAN FLURRIES THIS EVENING WITH GRADUAL
CLEARING THEN FOLLOWING DURING THE NIGHT FROM THE W. WITH
CLEARING...MINS COULD DROP NEAR ZERO IN THE TRADITIONAL COLD SPOTS
OVER THE INTERIOR W HALF. NEAR LAKE SUPERIOR WHERE THERE WILL BE
BETTER MIXING AND MODERATION FROM ONSHORE NW FLOW TO KEEP MIN TEMPS
IN THE TEENS.
SUNDAY...LINGERING LIGHT LES/FLURRIES OVER THE NE FCST AREA WILL END
IN THE MORNING AS THE INVERSION CONTINUES TO LWR AND MORE
IMPORTANTLY TEMPS AT INVERSION BASE RISE ABOVE -10C. AWAY FROM
DIMINISHING LIGHT LES E...IT SHOULD TURN OUT TO BE A MAINLY SUNNY
DAY UNDER A DEEP DRY AIR MASS. DRY AIR MASS AND SUNSHINE WORKING ON
THE LWR ALBEDO FORESTED LANDSCAPE OF UPPER MI WILL ASSIST THE WARM
UP...BUT STRONG INVERSION WILL HOLD BACK THE WARMING POTENTIAL OVER
WHAT IT COULD BE. FCST SOUNDINGS SUGGEST MIXING TO JUST ABV 925 MB
LOOK FOR HIGHS GENERALLY IN THE MID/UPPER 20S.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 446 AM EST SAT FEB 11 2012
UPPER TROUGH WILL BE ROTATING E OF THE AREA AT THE START OF THE LONG
TERM PERIOD...LEADING TO THE AREA BEING BETWEEN THE SPLIT FLOW OF
THE NRN STREAM RIDGE OVER THE CANADIAN PRAIRIES AND THE SRN STREAM
RUNNING ACROSS THE SRN FOURTH OF THE CONUS. THIS WILL KEEP THE AREA
UNDER QUIET WEATHER TO START THE PERIOD WITH A HIGH PRESSURE RIDGE
PUSHING OVER THE WRN CWA SUN NIGHT AND MON...WHILE BROAD H850-700
WAA INTENSIFIES OVER STATIONARY FRONT OVER SE ONTARIO.
SUN NIGHT...EXPECT A MOSTLY CLEAR NIGHT WITH THE HIGH PRESSURE RIDGE
PUSHING OVER THE AREA. LOWS WILL DEPEND ON HOW QUICKLY WINDS CAN
DECOUPLE ON MON NIGHT...AS GRADIENT BETWEEN STATIONARY FRONT AND
APPROACHING SFC RIDGE TRIES TO KEEP WINDS UP. BEST CHANCE FOR LIGHT
WINDS WILL BE CLOSER TO THE SFC RIDGE OVER THE SW HALF OF THE
CWA...WHERE PWAT VALUES FALL TO 40 PERCENT OF NORMAL. HAVE TRENDED
TOWARDS THE LOW END OF GUIDANCE...BUT NOT QUITE AS COLD AS IF THE
WAS HIGHER CONF FOR LIGHT WINDS.
MON...AREA WILL BE BETWEEN SFC TROUGH IN SE ONTARIO AND H500
SHORTWAVE AND ASSOCIATED HEIGHT FALLS MOVING THROUGH THE MID MISS
VALLEY AND APPROACHING THE LOWER GREAT LKS MON NIGHT. EXPECT A
MOSTLY SUNNY DAY FOR MUCH OF THE AREA...ALTHOUGH CLOUDS WILL ATTEMPT
TO PUSH ACROSS THE WI BORDER LATE IN THE AFTN WITH MOISTURE
INCREASING AHEAD OF THE SHORTWAVE. HIGHS WILL DEPEND ON AMNT OF
MIXING. MODELS INDICATING MIXING UP TO H900...WHICH WOULD PRODUCE
HIGHS OF 30-35. WITH ABUNDANT SUNSHINE TO START THE DAY...FELT TEMPS
WILL WARM UP QUICKLY AND ONLY MADE A DEGREE OR TWO ADJUSTMENT UP TO
GOING HIGHS.
MODELS CONSISTENT IN H850-650 MOISTURE MOVING INTO THE SRN HALF OF
THE AREA MON NIGHT AS THE SHORTWAVE MOVES SOUTH OF THE CWA. BUT WITH
LACK OF ISENTROPIC ASCENT...WAA...AND MAIN FORCING S OF THE CWA WITH
H500 HEIGHT FALLS...THINK PCPN CHANCES ARE FAIRLY LIMITED.
THEREFORE...HAVE JUST A SLIGHT CHANCE OVER THE SCNTRL CWA AND
CHANCES BRUSHING THE CITY OF MENOMINEE.
DAYS 4 THROUGH 7 /TUES THROUGH FRIDAY/...
SRN STREAM TROUGH WILL BEGIN TO DIG OVER THE SW CONUS ON
TUES...ALLOWING RIDGING TO DEVELOP OVER THE SRN/CNTRL PLAINS AND
CONTINUE INTO WED. MEANWHILE...TROUGH WILL START TO AMPLIFY OVER THE
CANADIAN ROCKIES IN THE NRN STREAM ON TUES AND ATTEMPT TO MERGE WITH
THE SRN STREAM WED NIGHT INTO THURS. THESE SITUATIONS TEND TO BE
DIFFICULT FOR MODELS...BUT 00Z GFS/ECMWF/GEM AND ASSOCIATED ENS
MEANS HANDLE THE LARGE SCALE FEATURES SIMILARLY BUT DO HAVE
DIFFICULTY WITH THE EMBEDDED SHORTWAVES. THUS...HAVE AVERAGE CONF
FOR MUCH OF THE EXTENDED PERIOD.
INITIAL SYSTEM EXITS THE AREA ON TUES...LEAVING AREA IN WSWRLY LLVL
FLOW AND H850 TEMPS AROUND -8C. THIS PROVIDES LIMITED POTENTIAL FOR
LES AND WILL LIKELY SEE MOSTLY CLOUDY SKIES LINGERING INTO WED WITH
NEXT POTENTIAL SHORTWAVE MOVING THROUGH...ALTHOUGH MODELS HAVE LARGE
DIFFERENCES IN INTENSITY.
NRN/SRN STREAMS LOOK TO PHASE ON THURS. WITH THE MORE DOMINATE SRN
STREAM...EXPECT SFC LOW DEVELOPMENT TO FOLLOW THE SRN STREAM TRACK
THAT WILL LIKELY TAKE IT THROUGH THE OHIO VALLEY OR LOWER GREAT LKS.
THIS WOULD BRUSH THE SE CWA AS BEST FORCING/MOISTURE REMAINS CLOSER
TO THE LOW. 00Z ECMWF DID TREND A LITTLE FARTHER NW WITH THE TRACK
OF THE LOW...SO WILL NEED TO WATCH ON FUTURE SHIFTS.
MODELS BEGIN TO DIVERGE HEADING INTO FRI WITH THE HANDLING OF THE
NRN STREAM FEATURES AND WHERE THE SRN STREAM UPPER TROUGH IS LOCATED
OVER THE SW CONUS. H850 TEMPS AROUND -11C WOULD LEAD TO SOME LES
POTENTIAL UNDER NW WINDS...BUT LLVL MOISTURE OVER THE W MAY BE
LIMITED. THEREFORE...ONLY MENTIONED CHANCE POPS OVER THE ERN AREAS
FAVORED BY NW WINDS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 832 AM EST SAT FEB 11 2012
LES IS EXPECTED TO REDEVELOP AT CMX AND IWD TODAY AS MOISTURE
INCREASES AGAIN WITH NW FLOW. EXPECT MVFR CONDITIONS TO GENERALLY
PREVAIL WITH ONLY BRIEF PERIODS OF IFR POSSIBLE. KCMX WILL HAVE THE
BEST CHANCE OF SEEING IFR CONDITIONS GIVEN MORE FAVORABLE WRLY FLOW
FOR LES AND POSSIBLE BLOWING SNOW AS WIND GUSTS EXCEED 25 KTS.
CONDITIONS WILL IMPROVE AT BOTH KIWD AND KCMX THIS EVENING AS WAA
WILL HELP SHUT OFF LES CHCS. AT SAW...NW FLOW WILL NOT BE FAVORABLE
FOR LES. MVFR CIGS SHOULD GIVE WAY TO VFR CONDITIONS THIS EVENING AS
WINDS BACK TO THE WNW.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 446 AM EST SAT FEB 11 2012
NNW WINDS TO 30KT WILL PERSIST WITH AMPLE INSTABILITY IN THE ARCTIC
AIRMASS MOVING OVER THE REGION. NW WINDS APPROACHING GALES TO 35 KT
ARE ALSO POSSIBLE THIS AFTERNOON INTO THIS EVENING OVER ERN LAKE
SUPERIOR. EXPECT HEAVY FREEZING SPRAY ACROSS THE ENTIRE LAKE THROUGH
TONIGHT WITH THE STRONG WINDS AND WAVE ACTION. LOOK FOR HEAVY
FREEZING SPRAY TO END ON SUNDAY AS THE AIRMASS WARMS AND WINDS
GRADUALLY DIMINISH. CONDITIONS WILL QUIET DOWN FOR THE EARLY PART OF
THE WORK WEEK AS A HIGH PRES RIDGE MOVES OVER THE UPPER GREAT LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ SUNDAY
FOR LSZ162-240>251-263>267.
GALE WARNING FROM 5 PM THIS AFTERNOON TO 3 AM EST SUNDAY FOR
LSZ248>250-265-266.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...SRF
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
447 AM EST SAT FEB 11 2012
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 446 AM EST SAT FEB 11 2012
LATEST WV IMAGERY AND RUC ANALYSIS REVEALS THE CENTER OF THE POLAR
VORTEX EAST OF HUDSON BAY WITH A MID/UPPER LEVEL TROUGH AXIS
EXTENDING SOUTH INTO THE CENTRAL GREAT LAKES. AT THE SFC...A 1044 MB
ARCTIC HIGH WAS CENTERED OVER THE DAKOTAS. RADAR IMAGERY AND SFC OBS
SHOW WIND PARALLEL LES BANDS FROM EAST OF MQT TO GRAND MARAIS BEING
SUPPORTED BY ENHANCED LOW-LVL CONVERGENCE FROM NW WIND FLOW ACROSS
MUCH OF LAKE SUPERIOR AND THEN LAND BREEZE CIRCULATION OFF OF
ONTARIO CAUSING A NE WIND OVER FAR ERN LAKE SUPERIOR. LES BANDS WITH
RETURNS TO 30 DBZ ARE FAIRLY WELL SPACED APART DUE TO VERY DRY
UPSTREAM AND LARGE SCALE ANTICYCLONIC FLOW ACROSS THE AREA. SURGE OF
MID TO LOW-LVL MOISTURE IN WAA PATTERN MOVING IN FROM NORTH OF LAKE
SUPERIOR IS SHOWING SIGNS OF ENHANCING LES BANDS ACROSS THE LAKE IN
THE PAST HR OR SO. THIS WILL BE SOMETHING TO MONITOR AS THE DAY
PROGRESSES TO SEE IF IT WILL BOOST LES ACCUMS DOWNWIND OF THE LAKE.
TODAY...AS 850-700 MB MOISTURE INCREASES IN A DEVELOPING WAA PATTERN
THERE COULD BE A BRIEF INCREASE IN LES INTENSITY FOR THE ERN
COUNTIES FAVORED BY A WNW/NW WIND. AS I SAID...BELIEVE ANY FLARE UP
IN LES WILL BE SHORT-LIVED SINCE WAA AND RISING 850 MB TEMPS WILL
EVENTUALLY FORCE THE DGZ ABV THE BEST OMEGA/UPWARD MOTION WITHIN THE
CONVECTIVE BOUNDARY LAYER BY THE LATE AFTERNOON/EVENING HRS. LONGER
FETCH ACROSS THE LAKE ALONG WITH MORE FAVORABLE LES PARAMETERS
SUGGEST BEST SNOW ACCUMULATIONS WILL BE OVER THE NE FCST
AREA...WHERE AMOUNTS IN THE 2 TO 4 INCH RANGE ARE POSSIBLE...JUST
BLO ADVISORY CRITERIA. ELSEWHERE...NEAR LAKE SUPERIOR EXPECT LES
AMTS GENERALLY 2 INCHES OR LESS.
TONIGHT...TROF ASSOCIATED WITH POLAR VORTEX E OF HUDSON BAY WILL
BEGIN SHIFTING E OF THE REGION...ALLOWING FOR PROMINENT RIDGING AND
WAA REGIME TO SET UP AND CONTINUE INTO SUN. LES WILL BE ONGOING SAT
EVENING OVER THE E AT LOCATIONS FAVORED BY A WNW/NW WIND OFF LAKE
SUPERIOR. HOWEVER...INVERSION QUICKLY SETTLES DOWN TO 4KFT OR LWR BY
LATE EVENING AND OVERNIGHT. ALSO...CONTINUED WAA WILL KEEP THE
DENDRITIC SNOW GROWTH TEMP ZONE (DGZ) UP ABOVE BEST UPWARD MOTION.
IN GENERAL...MIGHT SEE ANOTHER 1-2...POSSIBLY UP TO 3 INCHES OF SNOW
OVER THE NE FCST AREA SAT NIGHT. OUT W...INVERSION WILL ALREADY BE
SETTLING TO 3KFT OR LWR EARLY IN THE EVENING WITH DGZ ABOVE THE
INVERSION. GIVEN THE LOW INVERSION AND MODERATING AIRMASS...THERE
MAY NOT BE MUCH LEFT OTHER THAN FLURRIES THIS EVENING WITH GRADUAL
CLEARING THEN FOLLOWING DURING THE NIGHT FROM THE W. WITH
CLEARING...MINS COULD DROP NEAR ZERO IN THE TRADITIONAL COLD SPOTS
OVER THE INTERIOR W HALF. NEAR LAKE SUPERIOR WHERE THERE WILL BE
BETTER MIXING AND MODERATION FROM ONSHORE NW FLOW TO KEEP MIN TEMPS
IN THE TEENS.
SUNDAY...LINGERING LIGHT LES/FLURRIES OVER THE NE FCST AREA WILL END
IN THE MORNING AS THE INVERSION CONTINUES TO LWR AND MORE
IMPORTANTLY TEMPS AT INVERSION BASE RISE ABOVE -10C. AWAY FROM
DIMINISHING LIGHT LES E...IT SHOULD TURN OUT TO BE A MAINLY SUNNY
DAY UNDER A DEEP DRY AIR MASS. DRY AIR MASS AND SUNSHINE WORKING ON
THE LWR ALBEDO FORESTED LANDSCAPE OF UPPER MI WILL ASSIST THE WARM
UP...BUT STRONG INVERSION WILL HOLD BACK THE WARMING POTENTIAL OVER
WHAT IT COULD BE. FCST SOUNDINGS SUGGEST MIXING TO JUST ABV 925 MB
LOOK FOR HIGHS GENERALLY IN THE MID/UPPER 20S.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 446 AM EST SAT FEB 11 2012
UPPER TROUGH WILL BE ROTATING E OF THE AREA AT THE START OF THE LONG
TERM PERIOD...LEADING TO THE AREA BEING BETWEEN THE SPLIT FLOW OF
THE NRN STREAM RIDGE OVER THE CANADIAN PRAIRIES AND THE SRN STREAM
RUNNING ACROSS THE SRN FOURTH OF THE CONUS. THIS WILL KEEP THE AREA
UNDER QUIET WEATHER TO START THE PERIOD WITH A HIGH PRESSURE RIDGE
PUSHING OVER THE WRN CWA SUN NIGHT AND MON...WHILE BROAD H850-700
WAA INTENSIFIES OVER STATIONARY FRONT OVER SE ONTARIO.
SUN NIGHT...EXPECT A MOSTLY CLEAR NIGHT WITH THE HIGH PRESSURE RIDGE
PUSHING OVER THE AREA. LOWS WILL DEPEND ON HOW QUICKLY WINDS CAN
DECOUPLE ON MON NIGHT...AS GRADIENT BETWEEN STATIONARY FRONT AND
APPROACHING SFC RIDGE TRIES TO KEEP WINDS UP. BEST CHANCE FOR LIGHT
WINDS WILL BE CLOSER TO THE SFC RIDGE OVER THE SW HALF OF THE
CWA...WHERE PWAT VALUES FALL TO 40 PERCENT OF NORMAL. HAVE TRENDED
TOWARDS THE LOW END OF GUIDANCE...BUT NOT QUITE AS COLD AS IF THE
WAS HIGHER CONF FOR LIGHT WINDS.
MON...AREA WILL BE BETWEEN SFC TROUGH IN SE ONTARIO AND H500
SHORTWAVE AND ASSOCIATED HEIGHT FALLS MOVING THROUGH THE MID MISS
VALLEY AND APPROACHING THE LOWER GREAT LKS MON NIGHT. EXPECT A
MOSTLY SUNNY DAY FOR MUCH OF THE AREA...ALTHOUGH CLOUDS WILL ATTEMPT
TO PUSH ACROSS THE WI BORDER LATE IN THE AFTN WITH MOISTURE
INCREASING AHEAD OF THE SHORTWAVE. HIGHS WILL DEPEND ON AMNT OF
MIXING. MODELS INDICATING MIXING UP TO H900...WHICH WOULD PRODUCE
HIGHS OF 30-35. WITH ABUNDANT SUNSHINE TO START THE DAY...FELT TEMPS
WILL WARM UP QUICKLY AND ONLY MADE A DEGREE OR TWO ADJUSTMENT UP TO
GOING HIGHS.
MODELS CONSISTENT IN H850-650 MOISTURE MOVING INTO THE SRN HALF OF
THE AREA MON NIGHT AS THE SHORTWAVE MOVES SOUTH OF THE CWA. BUT WITH
LACK OF ISENTROPIC ASCENT...WAA...AND MAIN FORCING S OF THE CWA WITH
H500 HEIGHT FALLS...THINK PCPN CHANCES ARE FAIRLY LIMITED.
THEREFORE...HAVE JUST A SLIGHT CHANCE OVER THE SCNTRL CWA AND
CHANCES BRUSHING THE CITY OF MENOMINEE.
DAYS 4 THROUGH 7 /TUES THROUGH FRIDAY/...
SRN STREAM TROUGH WILL BEGIN TO DIG OVER THE SW CONUS ON
TUES...ALLOWING RIDGING TO DEVELOP OVER THE SRN/CNTRL PLAINS AND
CONTINUE INTO WED. MEANWHILE...TROUGH WILL START TO AMPLIFY OVER THE
CANADIAN ROCKIES IN THE NRN STREAM ON TUES AND ATTEMPT TO MERGE WITH
THE SRN STREAM WED NIGHT INTO THURS. THESE SITUATIONS TEND TO BE
DIFFICULT FOR MODELS...BUT 00Z GFS/ECMWF/GEM AND ASSOCIATED ENS
MEANS HANDLE THE LARGE SCALE FEATURES SIMILARLY BUT DO HAVE
DIFFICULTY WITH THE EMBEDDED SHORTWAVES. THUS...HAVE AVERAGE CONF
FOR MUCH OF THE EXTENDED PERIOD.
INITIAL SYSTEM EXITS THE AREA ON TUES...LEAVING AREA IN WSWRLY LLVL
FLOW AND H850 TEMPS AROUND -8C. THIS PROVIDES LIMITED POTENTIAL FOR
LES AND WILL LIKELY SEE MOSTLY CLOUDY SKIES LINGERING INTO WED WITH
NEXT POTENTIAL SHORTWAVE MOVING THROUGH...ALTHOUGH MODELS HAVE LARGE
DIFFERENCES IN INTENSITY.
NRN/SRN STREAMS LOOK TO PHASE ON THURS. WITH THE MORE DOMINATE SRN
STREAM...EXPECT SFC LOW DEVELOPMENT TO FOLLOW THE SRN STREAM TRACK
THAT WILL LIKELY TAKE IT THROUGH THE OHIO VALLEY OR LOWER GREAT LKS.
THIS WOULD BRUSH THE SE CWA AS BEST FORCING/MOISTURE REMAINS CLOSER
TO THE LOW. 00Z ECMWF DID TREND A LITTLE FARTHER NW WITH THE TRACK
OF THE LOW...SO WILL NEED TO WATCH ON FUTURE SHIFTS.
MODELS BEGIN TO DIVERGE HEADING INTO FRI WITH THE HANDLING OF THE
NRN STREAM FEATURES AND WHERE THE SRN STREAM UPPER TROUGH IS LOCATED
OVER THE SW CONUS. H850 TEMPS AROUND -11C WOULD LEAD TO SOME LES
POTENTIAL UNDER NW WINDS...BUT LLVL MOISTURE OVER THE W MAY BE
LIMITED. THEREFORE...ONLY MENTIONED CHANCE POPS OVER THE ERN AREAS
FAVORED BY NW WINDS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1228 AM EST SAT FEB 11 2012
LES IS EXPECTED TO REDEVELOP AT CMX AND IWD OVERNIGHT AS MOISTURE
INCREASES AGAIN WITH NW FLOW. HOWEVER...MAINLY MVFR CONDITIONS WILL
PREVAIL WITH ONLY BRIEF PERIODS OF IFR POSSIBLE. AT SAW...LES WILL
MOVE OVER TONIGHT BEFORE WINDS BECOME MORE NWLY LATE TONIGHT.
ANOTHER SURGE OF MOISTURE WILL PUSH INTO THE AREA EARLY SAT
AFTERNOON...INTENSIFYING LES AT CMX AND IWD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 446 AM EST SAT FEB 11 2012
NNW WINDS TO 30KT WILL PERSIST WITH AMPLE INSTABILITY IN THE ARCTIC
AIRMASS MOVING OVER THE REGION. NW WINDS APPROACHING GALES TO 35 KT
ARE ALSO POSSIBLE THIS AFTERNOON INTO THIS EVENING OVER ERN LAKE
SUPERIOR. EXPECT HEAVY FREEZING SPRAY ACROSS THE ENTIRE LAKE THROUGH
TONIGHT WITH THE STRONG WINDS AND WAVE ACTION. LOOK FOR HEAVY
FREEZING SPRAY TO END ON SUNDAY AS THE AIRMASS WARMS AND WINDS
GRADUALLY DIMINISH. CONDITIONS WILL QUIET DOWN FOR THE EARLY PART OF
THE WORK WEEK AS A HIGH PRES RIDGE MOVES OVER THE UPPER GREAT LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ SUNDAY
FOR LSZ162-240>251-263>267.
GALE WARNING FROM 5 PM THIS AFTERNOON TO 3 AM EST SUNDAY FOR
LSZ248>250-265-266.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...SRF
AVIATION...TITUS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1230 AM EST SAT FEB 11 2012
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 423 PM EST FRI FEB 10 2012
WV IMAGERY AND RUC ANALYSIS INDICATED CENTER OF THE POLAR VORTEX
EAST OF HUDSON BAY WITH A MID/UPPER LEVEL TROUGH AIX TO THE
SOUTHWEST THROUGH ERN LAKE SUPERIOR INTO CTNRL WI. AT THE SFC...A
1046 MB ARCTIC HIGH WAS LOCATED OVER SASK WITH A RIDGE EXTENDING
INTO NRN ONTARIO AND THROUGH THE PLAINS. NNW WINDS IN THE VERY COLD
AIRMASS SUPPORTED LES FOR LOCATIONS FAVORED BY NRLY WINDS.
HOWEVER...LES WAS DIMINISHING AND BANDS WERE SHIFTING WITH THE ACYC
FLOW...BACKING WINDS AND VERY DRY AIR WELL MIXED LOW LEVEL AIR
UPSTREAM WITH SFC DEWPOINTS TO NEAR -20F.
TONIGHT...WITH 850MB TEMPS AROUND -20C...LES WILL BE ONGOING IN
AREAS FAVORED BY NW WINDS. THE DRY AIR AND LOW INVERSION AOB 3KFT
WILL KEEP LES LIGHT INITIALLY. HOWEVER...WITH THE DENDRITIC SNOW
GROWTH TEMP ZONE (DGZ) FIRMLY IN THE CONVECTIVE LAYER...SHOULD STILL
BE ABLE TO GET A FEW INCHES OF FLUFFY SNOW MAINLY OVER THE NE FCST
AREA WHERE ENOUGH MOISTENING CAN OCCUR DESPITE THE DRY AIR.
WINDS OVER FAR SW UPPER MI MAY BACK SUFFICIENTLY TO CUT OVERWATER
TRAJECTORIES ENOUGH TO ALLOW FOR SOME CLEARING. EXPECT TEMPS THERE
TO FALL INTO THE SINGLE DIGITS BLO ZERO. ELSEWHERE...TEMPS ARE
EXPECTED TO REMAIN IN THE SINGLE DIGITS AND LOWER TEENS AS SFC-925MB
WINDS GENERALLY MAINTAIN SOME MODIFICATION OFF OF LAKE SUPERIOR.
SATURDAY...EXPECT LES INTENSITY TO INCREASE BY SAT AFTERNOON AS
850-700 MB MOISTURE INCREASES IN A DEVELOPING WAA PATTERN. WITH
850MB TEMPS MODERATING THROUGH THE DAY THE DGZ WILL CLIMB...BECOMING
MORE FAVORABLY POSITIONED IN THE CONVECTIVE LAYER/UPWARD MOTION
REGION. LONGER FETCH AND LONGER DURATION OF MORE FAVORABLE LES
PARAMETERS SUGGEST BEST SNOW ACCUMULATIONS WILL BE OVER THE NE FCST
AREA...WHERE AMOUNTS IN THE 2 TO 4 INCH RANGE ARE EXPECTED.
OVER WRN LAKE SUPERIOR...FLOW IS MORE WESTERLY AND ENHANCED
CONVERGENCE COULD DEVELOP BTWN THE PORCUPINE MTNS AND HOUGHTON. THIS
AREA OVER THE WRN CWA COULD ALSO SEE INCREASE IN LES.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 423 PM EST FRI FEB 10 2012
CURRENT PUSH OF ARCTIC AIR INTO THE UPPER LAKES WILL BE SHORT LIVED
AS POLAR VORTEX E OF HUDSON BAY RETREATS/REFORMS BACK TOWARD THE
POLE NEXT WEEK. THE RETREAT OF THE NRN STREAM AND A DISTINCT SPLIT
FLOW REGIME NEXT WEEK WILL BRING A RETURN OF THIS WINTERS PREVAILING
THEME OF ABOVE NORMAL TEMPS. WHETHER OR NOT THIS SPLIT FLOW LEADS TO
ANY SRN STREAM SYSTEMS REACHING THE UPPER GREAT LAKES REMAINS TO BE
SEEN. AT THIS POINT...IT STILL APPEARS THAT THE OVERALL DRY PATTERN
WILL PERSIST NEXT WEEK THOUGH THERE ARE MUCH INCREASED UNCERTAINTIES
IN POSSIBLE STREAM INTERACTIONS THAT MAY LEAD TO SOME STORMINESS IN
THE GREAT LAKES LATE IN THE WEEK.
BEGINNING SAT NIGHT...TROF ASSOCIATED WITH POLAR VORTEX E OF HUDSON
BAY WILL BEGIN SHIFTING E...RESULTING IN THE BEGINNINGS OF A WAA
REGIME WHICH WILL CONTINUE THRU SUN. LES WILL BE ONGOING SAT EVENING
OVER THE E AT LOCATIONS FAVORED BY A WNW/NW WIND OFF LAKE SUPERIOR.
HOWEVER...INVERSION QUICKLY SETTLES DOWN TO 4KFT OR LWR LATE EVENING
AND OVERNIGHT. ALSO...WAA BEGINS TO SHIFT DENDRITIC SNOW GROWTH TEMP
ZONE (DGZ) UP ABOVE BEST UPWARD MOTION. IN GENERAL...MIGHT SEE
ANOTHER 1-2 MAYBE 3 INCHES OF SNOW OVER THE NE FCST AREA SAT NIGHT.
OUT W...INVERSION WILL ALREADY BE SETTLING TO 3KFT OR LWR EARLY IN
THE EVENING WITH DGZ ABOVE THE INVERSION. GIVEN THE LOW INVERSION
AND MODERATING AIRMASS...THERE MAY NOT BE MUCH LEFT OTHER THAN
FLURRIES SAT EVENING WITH GRADUAL CLEARING THEN FOLLOWING DURING THE
NIGHT FROM THE W. FROM AN ISENTROPIC STANDPOINT...CONDENSATION PRES
DEFICITS ARE QUITE HIGH SAT NIGHT IN DEVELOPING WAA REGIME...SO
THERE SHOULDN`T BE MUCH IN THE WAY OF WAA CLOUDINESS. ALTHOUGH SKIES
WILL BE CLEARING FROM THE W...MAY NOT BE ABLE TO DECOUPLE COMPLETELY
AS A STRONG PRESSURE GRADIENT STILL EXISTS BETWEEN A 1040MB HIGH
SINKING INTO THE CENTRAL PLAINS AND A 1008MB TROUGH OVER WESTERN
HUDSON BAY/FAR NRN ONTARIO. MINS SHOULD END UP NEAR ZERO IN THE
TRADITIONAL COLD SPOTS OVER THE INTERIOR W HALF...RANGING UP TO THE
TEENS E NEAR LAKE SUPERIOR.
LINGERING LIGHT LES OVER THE NE FCST AREA WILL END SUN AS INVERSION
CONTINUES TO LWR AND MORE IMPORTANTLY TEMPS AT INVERSION BASE RISE
ABOVE -10C. AWAY FROM DIMINISHING LIGHT LES E...SUN SHOULD TURN OUT
TO BE A MAINLY SUNNY DAY UNDER A DEEP DRY AIR MASS. DRY AIR MASS AND
SUNSHINE WORKING ON THE LWR ALBEDO FORESTED LANDSCAPE OF UPPER MI
WILL ASSIST THE WARM UP...BUT STRONG INVERSION WILL HOLD BACK THE
WARMING POTENTIAL OVER WHAT IT COULD BE. FCST SOUNDINGS SUGGEST
MIXING TO 900MB...BUT THAT MIGHT BE A LITTLE OPTIMISTIC. MID/UPPER
20S SHOULD BE THE RULE.
POLAR VORTEX WILL BE RETREATING MON WITH UPSTREAM SPLIT FLOW
ADVANCING INTO THE CNTRL CONUS. IN THE SPLIT...MODEL GUIDANCE
CONTINUES TO INDICATE A SRN STREAM SHORTWAVE MOVING INTO THE MID
MISSISSIPPI VALLEY LATE MON. THERE HASN`T BEEN MUCH MODEL SPREAD
WITH THIS SYSTEM IN RECENT RUNS...AND LATEST ROUND OF GUIDANCE
MAINTAINS THE IDEA THAT THE BULK OF ASSOCIATED PCPN WILL PASS S OF
UPPER MI. SEE NO REASON TO STRAY FROM THAT SCENARIO RIGHT NOW.
SO...CLEAR SKIES SUN NIGHT WILL GIVE WAY TO A SLOW INCREASE IN
HIGH/MID CLOUDS FROM THE SW MON. MAINTAINED SLIGHT CHC POPS ACROSS
THE FAR S/SE MON NIGHT AS THE NRN FRINGE OF PCPN MAY BRUSH THAT
AREA.
TUE THRU FRI...UNDER SPLIT FLOW WITH MORE PROGRESSIVE NRN STREAM...
ARCTIC AIR WILL BE BOTTLED UP WELL TO THE N DURING THE MIDDLE AND
END OF NEXT WEEK. BENIGN/DRY WEATHER SHOULD CONTINUE TUE/WED. EVEN
LES WON`T BE A CONCERN WITH CONSENSUS 850MB TEMPS WARMER THAN -8C.
HEADING INTO THU/FRI...SOME RECENT GFS RUNS HAVE SUGGESTED POSSIBLE
STREAM INTERACTIONS SOMEWHERE FROM THE MISSISSIPPI VALLEY EASTWARD
THAT COULD LEAD TO A STORM SYSTEM IN THE GREAT LAKES AREA. TODAYS
12Z ECMWF RUN IS NOW BEGINNING TO SUGGEST THAT AS WELL. AS ALWAYS...
THERE IS LOW CONFIDENCE IN STREAM PHASING...AND IT GOES WITHOUT
SAYING THAT THERE IS TREMENDOUS UNCERTAINTY IN ANY TYPE OF
INTERACTION THAT FAR OUT IN A MODEL RUN. WILL BE SOMETHING TO
MONITOR IN THE COMING DAYS...BUT FOR NOW...FAVORED THE MORE
DISTINCT...SEPARATED FLOW REPRESENTED BY PREVIOUS ECMWF RUNS. AS A
RESULT...MAINTAINED A DRY FCST FOR THU/FRI THOUGH THERE COULD BE A
LITTLE -SN AT SOME POINT. AIR MASS REMAINS WARM ENOUGH TO PRECLUDE
ANY MENTION OF LES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1228 AM EST SAT FEB 11 2012
LES IS EXPECTED TO REDEVELOP AT CMX AND IWD OVERNIGHT AS MOISTURE
INCREASES AGAIN WITH NW FLOW. HOWEVER...MAINLY MVFR CONDITIONS WILL
PREVAIL WITH ONLY BRIEF PERIODS OF IFR POSSIBLE. AT SAW...LES WILL
MOVE OVER TONIGHT BEFORE WINDS BECOME MORE NWLY LATE TONIGHT.
ANOTHER SURGE OF MOISTURE WILL PUSH INTO THE AREA EARLY SAT
AFTERNOON...INTENSIFYING LES AT CMX AND IWD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 423 PM EST FRI FEB 10 2012
NNW WINDS TO 30KT WILL PERSIST WITH AMPLE INSTABILITY IN THE ARCTIC
AIRMASS MOVING OVER THE REGION. NW WINDS APPROACHING GALES TO 35 KT
ARE ALSO POSSIBLE SAT AFTERNOON INTO SAT EVENING OVER ERN LAKE
SUPERIOR. EXPECT HEAVY FREEZING SPRAY ACROSS THE ENTIRE LAKE TONIGHT
THROUGH SAT NIGHT WITH THE STRONG WINDS AND WAVE ACTION. LOOK FOR
HEAVY FREEZING SPRAY TO END ON SUNDAY AS THE AIRMASS WARMS AND WINDS
GRADUALLY DIMINISH. CONDITIONS WILL QUIET DOWN FOR THE EARLY PART OF
THE WORK WEEK AS A HIGH PRES RIDGE MOVES OVER THE UPPER GREAT LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ SUNDAY
FOR LSZ162-240>251-263>267.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...ROLFSON
AVIATION...TITUS
MARINE...JLB
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
655 PM EST SUN FEB 12 2012
.SYNOPSIS...
COLD AIR COMING ACROSS LAKE ONTARIO WILL KEEP LAKE EFFECT SNOWS
OVER PORTIONS OF CENTRAL NEW YORK INTO MONDAY. ON TUESDAY...LOW
PRESSURE WILL MOVE FROM THE OHIO VALLEY...THROUGH OUR
REGION...WHICH WILL BRING A CHANCE OF LIGHT SNOW.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
7 PM UPDATE...FORECAST ADJUSTED TO BE DEFINITIVE ON DETAILS FOR
LAKE EFFECT THIS EVENING THROUGH TONIGHT. TRANSITION FROM
MULTIBAND TO PREDOMINANT SINGLE BAND WILL OCCUR THE NEXT FEW
HOURS. HIGH RESOLUTION MODELS SUCH AS WRFARW...HRRR..AND RUC ARE
AGREEING THAT AS WIND FLOW CONTINUES TO BACK THIS EVENING...FETCH
DOWN LONG AXIS OF LAKE ONTARIO IGNITES MORE OF A SINGLE MAIN BAND
WITH HELP OF UPSTREAM HURON CONNECTION AS WELL /AT LEAST
INITIALLY/. PORTIONS OF THE ADVISORY THAT DID NOT GET AS MUCH SNOW
TODAY...LOOK TO GET IN A BETTER SET UP FOR TONIGHT AS THAT BAND
DEVELOPS...AND THEN SHIFTS FROM THE NORTHERN FINGER
LAKES...EASTWARD TO THE MOHAWK VALLEY WITH TIME OVERNIGHT INTO
MONDAY MORNING.
EXPECTED SNOW AMOUNTS HAVE BEEN ADJUSTED ACCORDINGLY...WITH A
SOLID 3 TO 5 ADDITIONAL INCHES EXPECTED IN THE HEAVIEST PART OF
THE BAND. LOCALIZED HIGHER AMOUNTS ARE POSSIBLE IF THE BAND CAN
STAY STATIONARY...BUT AT THIS TIME IT APPEARS THAT BAND WILL BE
SHIFTING WITH TIME. ACROSS THE REST OF THE AREA...WHAT REMAINS OF
SNOW SHOWERS WILL CONTINUE TO DIMINISH THIS EVENING AS BACKING
WINDS CUT OFF ACCESS TO MOISTURE...AND WARM AIR ADVECTION
CONTINUES ALOFT. YATES AND TIOGA COUNTIES HAVE NOW BEEN DROPPED
EARLY FROM THE ADVISORY. OTHER ZONES WILL PROBABLY FOLLOW AS THE
MAIN BAND FURTHER DEVELOPS AND THEN STARTS SHIFTING NORTH AND EAST
WITH TIME.
PREVIOUS DISCUSSION...
AS USUAL...SUBTLE FEATURES MAKING ALL THE DIFFERENCE
IN THE CRNT LE EVENT. SCNDRY FNT PASSING THIS AFTN BROKE A BAND
AWY FROM THE LAKE AND PRODUCED BRIEF HEAVIER SQUALLS WELL AWAY
FROM THE LAKE INTO THE TWIN TIERS. THIS AFTN AND EVE...BHD THE
FNT...WNW FLOW PRODUCING STREAMERS AND ADTNL LE OVER THE FINGER
LAKES WHERE UPWARDS OF 6 TO 10 INCHES HAS ALREADY FALLEN LAST NGT
AND TODAY. THIS EVE...FINAL APRCHG WV BEGINS WAA AND THE FLOW
BECOMES MORE WLY....AND IS FCST TO HOLD THERE THRU THE NGT INTO
MON. WRKG AGAINST HIER SNOW AMTS OVER ONEIDA WILL BE THE LACK OF A
GOOD UPSTREAM LAKE CONNECTION AS WAA LIMITS THE DELTA T AND
REACTION FROM THE LAKE. SO...XPCT SOLID ADVISORY SNOWS OVER ONEIDA
COUNTY TNGT WITH SOME LE LINGERING INTO MON. TO THE SOUTH...WILL
CONT THE ADVISORY AS ADTNL SNOWS SHD BE IN THE 2 TO 4 INCH
RANGE...BLO THE 12 HR CRITERIA FOR A WARNING.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
ENUF FLOW AND COLD AIR TO KEEP LE CONTG INTO MON.WAA...RDGG AND DRY AIR
SHD END THE SNOW DURING THE AFTN. MON NGT...DRY CONDS WITH WEAK
SFC HIPRES...ALTHOUGH HI CLDS SHD INCRS AND THE OH SYSTEM APRCHS.
ON TUE...NAM SEEMS A BIT STRONGER WITH THE WV AND EVENTUALLY FORMS
A CLSD SFC LOW OFF NEW ENG. EC STILL WEAKER WITH THE WV AND THE
SFC FEATURES. WITH THE STRONGER LOOK OF THE NAM...AND SURROUNDING
OFFICE/S LIKELY POPS...NUDGED OUR FCST POPS UP A BIT AS IT SEEMS
AS THOUGH AT LEAST SOME LGT PCPN SHD FALL OVER THE PD INTO WED
MRNG.
ON WED...AN EQUALLY WEAK SFC HI SLIDES IN FROM OH BRINGING LTL CHG
TO THE WX. LINGERING PCPN SHD END AND TEMPS RECOVER AS SOME SUN
PSBL.
ONCE AGAIN...TEMPS TO RETURN TO NEAR OR ABV NRML FOR THE SHRT TERM
WITH ARCTIC AIR LOCKED TO THE NORTH. THIS HAS INCRSD CONFIDENCE IN
TEMPS FCSTS AS MODEL GUID IN GOOD AGREEMENT FOR THE PD.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
WEDNESDAY NIGHT BEGINS WITH HIGH PRESSURE OVER THE CWA BEGINNING
TO WEAKEN AS A STRONG LOW PRESSURE SYSTEM DEVELOPS OVER THE
CENTRAL PLAINS AND MOVES NORTHEASTWARD INTO THE MIDWEST. MODELS
AGREE THAT THERE WILL BE SYSTEM, BUT HAVE SOME DISCREPANCY
REGARDING ITS EVOLUTION AND TRACK. THE GFS IS A LITTLE QUICKER
WITH IT AND A LITTLE FURTHER EAST, WITH THE LOW CENTERED OVER LAKE
ERIE BY 18Z THURSDAY. THE ECMWF HAS IT JUST TO THE WEST, NEAR
CHICAGO AT THE SAME TIME. THE ECMWF HAS THE LOW MORE DEVELOPED
THAN THE GFS, AS WELL AS IT WORKING WITH A STRONGER UPPER LEVEL
TROUGH. THIS ALLOWS MORE WARM AIR TO SURGE NORTH AHEAD OF THE COLD
FRONT ASSOCIATED WITH THE LOW, WHERE, THE GFS HAS SOME MINOR WAA.
GIVEN THE SIMILARITIES AS WELL AS DIFFERENCES, HAVE TIMED THE
PRECIPITATION THAT WILL BE CAUSED BY THIS SYSTEM TO BEGIN TO MOVE
IN LATER THURSDAY. HAVE ALLOWED FOR A MIX OF RAIN AND SNOW ATTM,
ALTHOUGH IT COULD BE A MIX BAG OF PRECIP, BUT THAT WOULD BE MORE
APPARENT AS TIME DRAWS SOMEWHAT CLOSER.
THE COLD FRONT WILL MAKE ITS PASSAGE THURSDAY NIGHT, WITH THE
ECMWF A LITTLE SLOWER AND MORE OF AN OCCLUDED FRONT MAKING ITS
WAY THROUGH. BUT, EITHER MODEL SHOWS A FRONTAL PASSAGE BY FRIDAY
MORNING. BEHIND THE FRONT, THE FLOW WILL TURN THE TYPICAL NW AND
THE SFC FLOW WILL LINE UP WITH THE 700MB FLOW. THIS WILL PROBABLY
CAUSE SOME LIGHT LAKE EFFECT SNOW TO DEVELOP. BY SATURDAY MORNING,
THE SFC FLOW WEAKENS AND THE 700MB FLOW SHOULD TURN MORE WESTERLY.
THIS WILL PUSH MOST OF THE LES NORTH TOWARDS THE TUG HILL, BUT MAY
KEEP SOME LIGHT SHOWERS AND/OR FLURRIES OVER THE REST OF THE CWA.
THIS WILL CONTINUE AS HIGH PRESSURE VERY SLOWLY BUILDS OVER THE
FORECAST AREA ON SUNDAY.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
A WEAK SURFACE TROUGH AND AN UPPER LEVEL LOW WILL KEEP A
NORTHWESTERLY FLOW ACROSS LAKE ONTARIO TONIGHT, WHICH WILL KEEP
LAKE EFFECT SNOW GOING THROUGH THE OVER NIGHT HOURS. THE FLOW DOES
SLOWLY AND SLIGHTLY SHIFT A LITTLE MORE WESTERLY AND HIGH PRESSURE
TRIES TO SLOWLY BUILD IN OVER THE AREA. THIS WILL PUSH MOST OF THE
BANDS OF SNOW TO THE NORTH, CAUSING THEM TO EVENTUALLY AFFECT ONLY
SYR AND RME. TAF SITES FURTHER TO THE SOUTH ARE BEGINNING TO SEE
VERY SLOW IMPROVEMENT AND ARE BOUNCING FROM VFR DOWN TO MVFR AND
EVEN IFR IN SOME CASES. THIS WILL COME TO AN END BY AROUND 04Z OR
SO. SNOW WILL END FIRST, THE CIGS WILL RISE. BY TOMORROW MORNING,
AVP, BGM, ELM, AND ITH SHOULD EVENTUALLY SCATTER OUT. THE OTHER
CONCERN WITH THE SNOW, IS, OF COURSE, VSBYS. THEY WILL DROP TO
POSSIBLY IFR TO LIFR LEVEL IN LOCALIZED AREAS UNDER THE HEAVIEST
OF SNOW BANDS. THIS SHOULD BE FOUND MORE TOWARDS THE LAKE PLAIN,
TO POSSIBLY AS FAR SOUTH AS CORTLAND COUNTY (KNO3).
WINDS ARE ALSO BEGINNING TO DIMINISH THIS EVENING. GUSTS ARE
DROPPING OFF AND WILL CONTINUE TO DO SO OVER THROUGH THE EARLY
EVENING HOURS. MOST SITES SHOULD SEE WINDS OUT OF THE WEST AROUND
10KTS. THEY WILL PICK UP AGAIN TOMORROW FROM THE NW BETWEEN 10 AND
15KTS, WITH SOME HIGHER GUSTS POSSIBLE.
.OUTLOOK...
TUE/WED...MVFR/IFR PSBL AT ALL TAF SITES IN LGT SNOW.
THUR...VFR.
FRI...MVFR POSSIBLE IN RAIN/SNOW.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...LAKE EFFECT SNOW ADVISORY FROM 10 PM THIS EVENING TO 1 PM EST
MONDAY FOR NYZ009-037.
LAKE EFFECT SNOW ADVISORY UNTIL 6 AM EST MONDAY FOR NYZ016>018-
025-036-044-045.
&&
$$
SYNOPSIS...DGM
NEAR TERM...DGM/MDP
SHORT TERM...DGM
LONG TERM...SLI
AVIATION...SLI
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
1030 PM EST SUN FEB 12 2012
.SYNOPSIS...
STRONG ARCTIC HIGH PRESSURE WILL BUILD OVER THE REGION THROUGH
MONDAY. AN AREA OF LOW PRESSURE WILL MOVE BY TO THE SOUTH ON
TUESDAY. HIGH PRESSURE WILL AGAIN BUILD OVER THE MID ATLANTIC ON
WEDNESDAY BEFORE ANOTHER SYSTEM APPROACHES THE REGION THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
AS OF 10 PM SUN...WEAK LEE TROFFING OVER WRN NC HAS RESULTED IN
LIGHT SW WINDS DEVELOPING OVER INLAND SECTIONS OF ERN NC PAST FEW
HOURS...PRODUCING STEADY TEMPS AND EVEN RISING IN A FEW LOCATIONS.
LATEST RUC13 AND NAM12 HAVE PICKED UP ON THIS TREND AND SHOW TROF
MOVING OFF COAST AFTER MIDNIGHT WITH RIDGING BUILDING IN OVERNIGHT.
OTHER THAN WIND DIRECTIONS AND HOURLY TEMP TRENDS...MAIN CHANGE WITH
UPDATE WERE TO RAISE MIN TEMPS A FEW DEGS ON OUTER BANKS WHERE WINDS
EXPECTED TO KEEP READINGS ABOVE MID 20S.
/PREVIOUS DISCUSSION/
AS OF 130 PM SUN...HIGH PRES CENTERED OVER THE LOWER MISS RIVER
VALLEY WILL CONTINUE TO BUILD INTO THE REGION TONIGHT. WINDS ARE
GRADUALLY DIMINISHING THIS AFTERNOON AND HAVE ALLOWED THE WIND
ADVISORY TO EXPIRE ACROSS THE OBX AND DOWNEAST BUT WILL LIKELY SEE
GUSTS TO AROUND 30 MPH ACROSS THE OBX THIS AFTERNOON. THE NAM/CMC
MODELS INDICATING A SLIGHT SURGE IN WINDS THIS EVENING BUT IT IS
NOT SO EVIDENT IN COARSER MODELS SUCH AS THE ECMWF AND GFS. WITH A
STRONG INVERSION DEVELOPING EARLY THIS EVENING AWAY FROM THE COAST
DON`T THINK IT WILL SO EVIDENT INLAND OTHER THAN MAINTAINING LIGHT
MIXING AROUND 5-10 MPH...HOWEVER COASTAL AREAS AND ESPECIALLY THE
OBX WILL LIKELY SEE 15-25 MPH WINDS THIS EVENING BEFORE
DIMINISHING TO AROUND 10-15 MPH AFTER MIDNIGHT. WITH CLEAR SKIES
AND A STRONG INVERSION DEVELOPING THIS EVENING EXPECT TEMPS TO
QUICKLY FALL INTO THE 20S...HOWEVER LIGHT MIXING MAY PREVENT
MAXIMUM RADIATIONAL COOLING OVERNIGHT. MOS GUIDANCE INDICATING
LOWS AROUND 20 INLAND TO M/U20S COAST BUT WITH DEWPOINTS IN THE
SINGLE DIGITS THIS AFTERNOON THINK SHELTERED AREAS COULD EASILY
DROP INTO THE TEENS. WILL LIKELY GO A LITTLE BELOW GUIDANCE FOR
LOWS TONIGHT THINKING WINDS MAY BECOME LIGHT ENOUGH A FEW HOURS
BEFORE DAYBREAK FOR ADDITIONAL RADIATIONAL COOLING TO TAKE EFFECT.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
AS OF 130 PM SUN...HIGH PRES WILL BECOME CENTERED ACROSS ERN NC
MONDAY WITH SHORTWAVE RIDGING BUILDING ALOFT. EXPECT ABUNDANT
SUNSHINE ACROSS THE AREA WITH A VERY DRY AIRMASS IN PLACE...PW`S
AROUND 0.15"...BUT COULD SEE HIGH CLOUDS INCREASE THROUGH THE DAY
IN ADVANCE OF A SHORTWAVE TROUGH MOVING INTO THE MISS RIVER
VALLEY. LOW LEVEL THICKNESSES INCREASE TO AROUND 1310M WHICH
SHOULD ALLOW TEMPS TO WARM TO A FEW DEGREES EITHER SIDE OF 50
EXCEPT M40S ALONG THE COAST.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
AS OF 200 PM SUN...HIGH PRESSURE WILL CONTINUE JUST OFFSHORE MON
NIGHT. SHLD HAVE ENOUGH BREAKS IN CLOUDS...ESPCLY EARLY...FOR
TEMPS TO DROP TO AROUND 30 MOST SPOTS. THE WEAK SRT WAVE WILL
MOVE THROUGH TUE...LOOKS LIKE ANY PRECIP WITH THIS WOULD BE LIGHT
AND MAINLY NEAR OR E OF CST AND MADE VERY LITTLE CHANGE TO PREV
FCST WHICH ALREADY INDICATED BEST PRECIP CHCS OVER ERN SECTIONS.
WEAK HIGH WILL BUILD OVER WED WITH NO PRECIP AND TEMPS IN THE UPR
50S TO LOWER 60S. COLD FRONT WILL APPROACH FROM THE W
THU...MOISTURE WILL BE INCREASING LATE AND CONT CHC POPS INLAND.
WITH SW FLOW SHLD HAVE HIGHS MOSTLY IN THE 60 TO 65 DGR RANGE. THE
FRONT WILL CROSS AREA LATER THU NIGHT AND EARLY FRI AND CONT CHC
POPS THIS PERIOD WITH DRYING FROM W TO E EXPECTED FRI AS FRONT
MOVES OFFSHORE. WITH WARM START FRI AND CAA NOT LOOKING OVERLY
IMPRESSIVE EXPECT HIGHS IN THE UPR 50S TO LOWER 60S. A BIT COOLER
OVER THE WEEKEND AS HGTS ALOFT DROP...HIGHS MOSTLY IN THE 50S WITH
NO PRECIP EXPECTED AT THIS TIME.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
SHORT TERM /00Z MONDAY THROUGH 00Z TUESDAY/...
AS OF 630 PM SUN...HIGH CONFIDENCE IN VFR SKC CONDITIONS THROUGH TAF
PERIOD....WITH HIGH PRES AND VERY DRY AIRMASS CONTINUING TO BUILD
OVER AREA.
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 200 PM SUN...PREDOMINATE VFR CONDITIONS EXPECTED THROUGH THE
TAF PERIOD. SUB-VFR CONDITIONS POSSIBLE LATE TUE AND TUE NIGHT AS
WEAK SHORTWAVE CROSSES WITH LIGHT SHRA POSSIBLE. ANOTHER ROUND OF
SHRA WILL ALSO BE POSSIBLE LATE THU/THU NIGHT AHEAD OF COLD FRONT
WITH REDUCED CIGS. SOME PATCHY LATE NIGHT FOG CANNOT BE RULED OUT
ESPCLY MON NIGHT AND WED NIGHT WHEN WINDS SHLD BE QUITE LIGHT.
&&
.MARINE...
SHORT TERM /THROUGH MONDAY/
AS OF 1000 PM SUN...WITH RECENT OBS OF GUSTS TO 24 KT AT CAPE
LOOKOUT AND 25 KT AT FRYING PAN BUOY...WILL LET MARGINAL SCA FOR SRN
WATERS CONTINUE UNTIL MIDNIGHT. SEAS OVER OUTER PORTIONS OF NRN
WATERS STILL LIKELY AROUND 6 FT THUS SCA THERE UNTIL LATE TONIGHT.
/PREVIOUS DISCUSSION/
AS OF 130 PM SUN...WINDS CONTINUE TO DIMINISH ACROSS THE WATERS
THIS AFTERNOON AND ARE LESS THAN 25 KT AT AVAILABLE SENSORS ACROSS
THE WATERS. COULD SEE A SLIGHT SURGE BACK TO AROUND 25 KT ACROSS
THE COASTAL WATERS THIS EVENING AS INDICATED BY THE NAM AND CMC
MODELS BUT COARSER MODELS AREN`T AS STRONG WITH THE SURGE. WILL
HANG ON TO THE SCA SOUTH OF OCRACOKE INLET THROUGH THIS EVENING
BECAUSE OF THIS POTENTIAL SURGE. DON`T THINK THE SURGE WILL BE
QUITE AS STRONG ACROSS THE SOUNDS BUT COULD SEE OCCASIONAL GUSTS
25 KT THIS EVENING MAINLY ACROSS THE PAMLICO SOUND BUT DON`T PLAN
ON HOLDING ONTO THE SMALL CRAFT ADVISORY IN THE SOUNDS AT THIS
TIME.
SEAS ARE SUBSIDING THIS AFTERNOON AND ARE GENERALLY 6-9 FT
NORTHERN WATERS AND 2-5 FT SOUTHERN WATERS. SEAS WILL CONTINUE TO
SUBSIDE THROUGH THE OVERNIGHT AND WAVEWATCH PROGS SEAS TO BE BELOW
6 FT ACROSS THE WATERS NORTH OF OCRACOKE INLET BY LATE TONIGHT.
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 200 PM SUN...GOOD BOATING CONDITIONS EXPECTED MON NIGHT THRU
WED NIGHT WITH WEAK GRDNT OVER THE REGION PRODUCING WINDS 15 KTS
OR LESS AND SEAS 1 TO 3 FEET. SW WINDS WILL BEGIN TO INCREASE THU
AND PEAK THU NIGHT AHEAD OF APPROACHING COLD FRONT...FOR NOW KEPT
WINDS AND SEAS BELOW SCA THU NIGHT WITH POSS SOME 5 FT SEAS FAR
OUTER WTRS IN SW FLOW. AT THIS POINT LITTLE TO NO SURGE EXPECTED
IN WAKE OF FRONT FRI SO W TO NW SHLD BE MAINLY AOB 15 KTS WITH
SEAS 2 TO 4 FT.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST MONDAY FOR AMZ150-152-154.
SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR AMZ156-158.
&&
$$
SYNOPSIS...SK
NEAR TERM...JBM/SK
SHORT TERM...SK
LONG TERM...RF
AVIATION...JBM/RF
MARINE...JBM/RF/SK
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
956 PM CST SUN FEB 12 2012
.DISCUSSION...
UPPER LEVEL RIDGE WAS OVER WESTERN CANADA WITH AN UPPER TROUGH
EMBEDDED TO THE SOUTHEAST. LARGE SCALE TROUGH WAS OVER THE DESERT
SOUTHWEST. BOTH RIDGE AND TROUGH FORECAST TO SLOW MOVE EAST. WATER
VAPOR LOOP INDICATE A SHORT WAVE OVER FAR SOUTHERN SASK AND WAS
MOVING EAST ABOUT 15 KNOTS.
SURFACE DEWPOINTS WERE SLOWLY RISING TO THE SOUTH AND WEST AND SHOULD
CONTINUE OVERNIGHT. PRECIPITABLE WATER RISES FROM THE SOUTH AND WEST
OVERNIGHT. SURFACE RIDGE AXIS WAS OVER THE FAR EASTERN ZONES
MID LEVEL CLOUDS WERE DEVELOPING OVER EASTERN SD. MODELS ARE FAST
WITH THE MOISTURE/CLOUDS MOVING NORTHEAST. RUC WAS THE SLOWEST OF
THE MODELS BUT STILL TOO FAST. WILL GO A LITTLE COLDER IN THE SNOW
FIELD. TEMPERATURES WERE FALLING FAST IN EASTERN ZONES UNDER SURFACE
RIDGE AXIS. SO COLDER EAST. LITTLE CHANGE TO TEMPS OVER
SOUTH/SOUTHWEST ZONES.
&&
.PREVIOUS DISCUSSION.../ISSUED 227 PM CST SUN FEB 12 2012/
WITH THE CONTINUED ABSENCE OF ANY PCPN CHANCES TEMPS WILL REMAIN
THE MAIN FORECAST ISSUE OVER THE SHORT TERM. WILL STICK WITH A
MODEL BLEND FOR THIS PORTION OF THE FORECAST.
TONIGHT...REGION STILL CLOUD FREE BUT THERE MAY ACTUALLY BE SOME
CLOUD COVER ACROSS PORTIONS OF THE FA TONIGHT. MODELS SHOW SOME
INCREASING POTENTIAL FOR A LITTLE CLOUD COVER ACROSS MAINLY THE
SOUTHERN FA TONIGHT. WINDS LOOK STAY UP THROUGH THE NIGHT WITH
MAINLY A SOUTHERLY DIRECTION. TEMPS WILL BE MILDEST ACROSS THE
SNOW FREE AREAS LIKE THEY HAVE BEEN THE PAST FEW NIGHTS.
MON-WED...WILL HAVE VERY LITTLE WIND AROUND AGAIN ON MON WITH
QUITE A BIT OF SUN. MAY HAVE SOME LINGERING CLOUDS ACROSS THE
SOUTH/SE. 850MB TEMPS ON MONDAY LOOK TO WARM A COUPLE OF DEGREES
OVER TODAYS THEN COOL BACK DOWN A BIT ON TUE. 850MB TEMPS THEN
RISE A FEW DEGREES ON WED SO OVERALL NOT A LOT OF DIFFERENCE OVER
THE NEXT THREE DAYS. HOWEVER THE MID FEBRUARY SUN IS DOING A GOOD
JOB WARMING THE BARREN BLACK FIELDS. MAY ALSO GET SOME WESTERLY
COMPONENT TO THE SFC WINDS WHICH COULD ALSO HELP BOOST TEMPS.
LONG TERM (THU-SUN)...
BROAD SOMEWHAT SPLIT MID LEVEL TROUGH ACROSS FA WITH ENERGY WELL TO
OUR SOUTH. MODELS NOT HANDLING WHAT HAPPENS IN THE NORTHERN STREAM
WITH FLOW SO WEAK. WITH MOISTURE/FORCING LACKING WILL KEEP FORECAST
DRY WITH AT OR ABOVE AVERAGE TEMPERATURES CONTINUING.
&&
.AVIATION...
FOG LOOP/SURFACE OBS INDICATED SCT CIGS AROUND 10 THOUSAND FT OVER
PARTS OF EASTERN SD. CLOUD PATCHES WERE MOVING NORTHEAST ABOUT 15 TO
20 KNOTS. CLOUD PATCHES TRYING TO DEVELOP OVER SOUTHEAST ND WHICH
APPEAR THEN DISAPPEAR. MAY ADD MID LEVEL CLOUDS LATE FOR BJI AND
POSSIBLY FAR.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
HOPPES
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1154 AM CST SAT FEB 11 2012
.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
249 AM CST SAT FEB 11 2012
MAIN FORECAST CONCERN IS ON PRECIPITATION FOR MONDAY
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS
SHOWED TROUGHING COMING INTO CALIFORNIA...RIDGING FROM ARIZONA INTO
SASKATCHEWAN...AND TROUGHING FROM QUEBEC INTO ILLINOIS. THE FORECAST
AREA LIES IN SUBSIDENCE IN THE WAKE OF THE TROUGHING...PROMOTING A
FEED OF DRIER AIR INTO THE FORECAST AREA. 00Z MPX SOUNDING AS WELL
AS A PRECIPITABLE WATER PLOT OF 00Z RAOB DATA ACROSS THE UPPER
MIDWEST REFLECTIVE OF THE DRY AIR...WITH VALUES AROUND 0.05 OF AN
INCH OR 25 PERCENT OF NORMAL. WITH ALL THE DRY AIR...SKIES ARE
CLEAR. ARCTIC AIR SLOWLY FLOWING IN TOO WITH THE DRY AIR ON A
SUSTAINED 10 TO 15 MPH NORTHWEST WIND. TEMPERATURES HAVE FALLEN INTO
THE SINGLE DIGITS ABOVE ZERO. THE LACK OF SNOW COVER AND PERSISTENT
WIND KEEPING TEMPERATURES FROM FALLING MUCH LOWER. COMBINATION OF
THE WIND AND TEMPERATURES RESULTING IN WIND CHILLS MOSTLY IN THE
SINGLE DIGITS OR TEENS BELOW ZERO. AREA OF HIGH PRESSURE ASSOCIATED
WITH THE SUBSIDENCE FAR OFF TO THE WEST...OVER THE DAKOTAS. NO BIG
CHANGE IN 850MB TEMPS FROM 12Z FRI TO 00Z SATURDAY AT BIS...ABR AND
MPX...ALL SITTING BETWEEN -17 AND -20C. HOWEVER...DVN AND GRB WHICH
WERE ALONG THE ARCTIC FRONT AT 12Z DROPPED 9 TO 11C BY 00Z.
TODAY THROUGH SUNDAY...UPPER RIDGING SEEN OVER ARIZONA AND UTAH IS
FORECAST TO BUILD EAST INTO THE PLAINS AND EVENTUALLY THE UPPER
MISSISSIPPI RIVER VALLEY BY LATE SUNDAY...DUE TO TROUGHING MOVING
INTO THE ROCKIES AND FOUR CORNERS REGION. THE FORECAST AREA WILL
REMAIN ON THE EAST SIDE OF THE UPPER RIDGING...PROMOTING SUBSIDENCE
AND CONTINUED DRY AIR ADVECTION. HOWEVER...THE BUILDING HEIGHTS IN
CONJUNCTION WITH THE LACK OF SNOW COVER AND PLENTY OF SUN SHOULD
HELP THE ARCTIC AIRMASS MODERATE THIS WEEKEND. 850MB TEMPS REFLECT
THE MODERATING...CLIMBING TO AROUND -12C AT 00Z SUNDAY AND -6C AT
00Z MONDAY. THE DRY AIRMASS IN PLACE SHOULD ALSO PROMOTE GOOD
MIXING. GIVEN 850MB TEMPS TODAY...HIGHS ARE ONLY EXPECTED IN THE MID
TEENS TO AROUND 20. THE BLUSTERY NORTHWEST WIND WILL MAKE IT FEEL
COOLER...THOUGH...WITH WIND CHILLS ONLY CLIMBING TO AROUND ZERO.
PLENTY OF WIND ANTICIPATED TONIGHT GIVEN THE SURFACE RIDGE TAKING A
TRACK TO OUR SOUTHWEST. THIS WIND SHOULD KEEP LOWS MOSTLY IN THE
SINGLE DIGITS ABOVE ZERO. ANTICIPATING WE CAN TACK ON ANOTHER 10
DEGREES OF WARMING FOR SUNDAY GIVEN THE 6C JUMP IN 850MB TEMPS.
REGARDING THE WIND CHILL ADVISORY...VERY MARGINAL CONDITIONS AT
BEST. SINCE IT IS ALREADY UP AND WIND CHILLS ARE AT LEAST IN THE
TEENS BELOW ZERO...FIGURE IT IS NOT WORTH CANCELING.
SUNDAY NIGHT THROUGH MONDAY NIGHT...FOCUS TURNS TO THE TROUGHING
OVER THE WESTERN U.S AT 00Z MONDAY. GOOD MODEL AGREEMENT EXISTS FOR
THIS TROUGHING TO CROSS THE PLAINS ON MONDAY...THEN SHEAR APART
MONDAY NIGHT AS IT CROSSES THE FORECAST AREA AND THROUGH THE OHIO
VALLEY. BEST 500MB HEIGHT FALLS FOR THE FORECAST AREA OCCUR MONDAY
AFTERNOON AND EVENING...RANGING FROM 40 TO 70 METERS PER 12 HOURS...
HIGHEST IN THE FAR SOUTHERN SECTIONS OF THE AREA. SO THE DPVA
FORCING IS FAIRLY DECENT. ISENTROPIC LIFT FIELDS...ON THE OTHER
HAND...ARE TERRIBLE WITH BASICALLY VERY LITTLE IF ANY NET ADIABATIC
OMEGA FROM EITHER THE 11.00Z NAM OR GFS. BEST 850 TO 700MB MOISTURE
TRANSPORT ALSO NOT THAT IMPRESSIVE...MOSTLY FOCUSED IN MISSOURI...
ILLINOIS AND ARKANSAS. SO BASICALLY ALL PRECIPITATION PRODUCTION
WILL COME FROM THE 500MB HEIGHT FALLS ACTING ON THE WEAKER MOISTURE
BEING TRANSPORTED UP INTO THE AREA. CERTAINLY GOOD MODEL AGREEMENT
EXISTS OF PRECIPITATION SPREADING SOUTHWEST TO NORTHEAST ACROSS MUCH
OF THE FORECAST AREA ON MONDAY...ESPECIALLY DURING THE AFTERNOON...
WHICH SEEMS REASONABLE. RAISED PRECIPITATION CHANCES UP A LITTLE
MORE FOR THE AFTERNOON...MAINLY ALONG AND SOUTH OF I-90. THINK THE
11.00Z NAM QPF IS A LITTLE TOO HIGH GIVEN LACK OF ISENTROPIC LIFT
AND STRONGER MOISTURE TRANSPORT. STILL...COULD PICK UP ANYWHERE FROM
A HALF INCH TO TWO INCHES OF SNOW OUT OF THE EVENT...HIGHEST ACROSS
THE SOUTH WHERE THE BETTER FORCING IS. PRECIPITATION SHOULD SLOWLY
DIMINISH MONDAY NIGHT AS THE UPPER TROUGHING SHEARS APART...REDUCING
THE DPVA LIFT. REGARDING TEMPERATURES...WITH THE PRECIPITATION AND
CLOUDS TRENDING SLOWER TO MOVE IN FOR SUNDAY NIGHT INTO MONDAY
MORNING...LOWERED TEMPERATURES A FEW DEGREES SUNDAY NIGHT AND STAYED
WITH A NORMAL DIURNAL TREND. POTENTIAL DOES EXIST MONDAY MORNING FOR
A LITTLE SUN NORTH OF I-94...THUS HIGHS ON MONDAY END UP WARMEST
NORTH OF I-94. SOUTHERLY ADVECTION OF WARM AIR AHEAD OF THE TROUGH
SHOULD RESULT IN HIGHS AGAIN IN THE UPPER 20S TO AROUND 30. WITH
PLENTY OF CLOUDS LINGERING MONDAY NIGHT AND LITTLE IN THE WAY OF
COLD ADVECTION...ANTICIPATING TEMPERATURES TO ONLY DROP AROUND 5
DEGREES.
.LONG TERM...TUESDAY THROUGH FRIDAY NIGHT
249 AM CST SAT FEB 11 2012
LONG TERM FORECAST LOOKS A LITTLE MORE UNCERTAIN TODAY...THOUGH THE
FEATURES SEEN YESTERDAY OF A SPLIT FLOW PATTERN REMAIN. THE BIGGEST
UNCERTAINTY IS WEDNESDAY NIGHT AND THURSDAY. DURING THIS PERIOD...
THE NEW 11.00Z ECMWF SUGGESTS TROUGHING COMING OUT OF THE SOUTHWEST
U.S. AND EVENTUALLY PHASING WITH A NORTHERN STREAM SHORTWAVE TROUGH
NEAR THE FORECAST AREA. THE RESULT WOULD PROBABLY BE AN
ADVISORY-TYPE WET SNOW EVENT FOR THE SOUTHEASTERN HALF OF THE
FORECAST AREA. PROBLEM IS...THE ECMWF IS THE ONLY MODEL SHOWING THIS
PHASING POTENTIAL. THE 11.00Z GFS/UKMET KEEP THE TWO SEPARATED WITH
THE SOUTHWESTERN TROUGH EJECTING FARTHER SOUTH. MEANWHILE...THE
11.00Z CANADIAN HAS MORE FOCUS ON THE NORTHERN STREAM FEATURE AND
PRODUCES A FAIRLY AMPLIFIED TROUGH OVER MINNESOTA ON THURSDAY. THE
11.00Z GFS ENSEMBLES DEPICT A SIMILAR AMOUNT OF UNCERTAINTY.
THEREFORE...FOR NOW FOLLOWED A CONSENSUS BLEND FOR PRECIPITATION
CHANCES WHICH END UP 20-40. PLUS...IT IS HARD TO TRUST PHASING THIS
FAR OUT.
OTHERWISE...PRECIPITATION FROM MONDAY NIGHT SHOULD FOR THE MOST PART
END TUESDAY AS THE LINGERING SHORTWAVE TROUGH FALLS APART. THIS
LEAVES DRY CONDITIONS FOR TUESDAY NIGHT AND WEDNESDAY...WHICH SHOULD
ALSO BE ASSOCIATED WITH SOME SMALL 500MB HEIGHT RISES AND A SURFACE
RIDGE OF HIGH PRESSURE. AFTER WHATEVER HAPPENS WITH THE WEDNESDAY
NIGHT THROUGH THURSDAY TIME PERIOD...GOOD AGREEMENT EXISTS OF A
WEST-NORTHWEST FLOW PATTERN HEADING INTO NEXT WEEKEND WITH HARD TO
TIME SHORTWAVES MOVING THROUGH THE FLOW. GIVEN THAT HIGH PRESSURE
SHOULD DOMINATE ACROSS THE SOUTHERN U.S. IN THE WAKE OF THE THURSDAY
SYSTEM...PREVENTING MOISTURE RETURN FROM THE GULF OF MEXICO FOR A
LITTLE WHILE...KEPT CONDITIONS DRY FOR FRIDAY.
ONE THING THAT DOES LOOK CERTAIN FOR THE LONG TERM PERIOD IS
TEMPERATURES TO REMAIN AT OR ABOVE NORMAL. A BRIEF SHOT OF COOL AIR
MAY COME THROUGH ON THURSDAY WITH 850MB TEMPS FALLING TO -6 TO -8C.
STILL...THIS WOULD BE ABOVE NORMAL. STAYED PRETTY MUCH WITH A BLEND
OF ALL GUIDANCE FOR TEMPERATURES AS IT SEEMS REASONABLE AT THIS
POINT.
&&
.AVIATION...THROUGH 18Z SUNDAY
1152 AM CST SAT FEB 11 2012
BRISK NORTHWEST WINDS WILL PERSIST THROUGH THIS AFTERNOON AS THE
AREA REMAINS UNDER A TIGHT PRESSURE GRADIENT. THE WINDS WILL
SUBSIDE THIS EVENING WITH SUNSET. OTHERWISE...LOOK FOR MOSTLY
CLEAR/VFR CONDITIONS THROUGH SUNDAY AS HIGH PRESSURE REMAINS THE
DOMINANT WEATHER FEATURE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
746 AM CST SAT FEB 11 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...DAS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
532 AM CST SAT FEB 11 2012
.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
249 AM CST SAT FEB 11 2012
MAIN FORECAST CONCERN IS ON PRECIPITATION FOR MONDAY
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS
SHOWED TROUGHING COMING INTO CALIFORNIA...RIDGING FROM ARIZONA INTO
SASKATCHEWAN...AND TROUGHING FROM QUEBEC INTO ILLINOIS. THE FORECAST
AREA LIES IN SUBSIDENCE IN THE WAKE OF THE TROUGHING...PROMOTING A
FEED OF DRIER AIR INTO THE FORECAST AREA. 00Z MPX SOUNDING AS WELL
AS A PRECIPITABLE WATER PLOT OF 00Z RAOB DATA ACROSS THE UPPER
MIDWEST REFLECTIVE OF THE DRY AIR...WITH VALUES AROUND 0.05 OF AN
INCH OR 25 PERCENT OF NORMAL. WITH ALL THE DRY AIR...SKIES ARE
CLEAR. ARCTIC AIR SLOWLY FLOWING IN TOO WITH THE DRY AIR ON A
SUSTAINED 10 TO 15 MPH NORTHWEST WIND. TEMPERATURES HAVE FALLEN INTO
THE SINGLE DIGITS ABOVE ZERO. THE LACK OF SNOW COVER AND PERSISTENT
WIND KEEPING TEMPERATURES FROM FALLING MUCH LOWER. COMBINATION OF
THE WIND AND TEMPERATURES RESULTING IN WIND CHILLS MOSTLY IN THE
SINGLE DIGITS OR TEENS BELOW ZERO. AREA OF HIGH PRESSURE ASSOCIATED
WITH THE SUBSIDENCE FAR OFF TO THE WEST...OVER THE DAKOTAS. NO BIG
CHANGE IN 850MB TEMPS FROM 12Z FRI TO 00Z SATURDAY AT BIS...ABR AND
MPX...ALL SITTING BETWEEN -17 AND -20C. HOWEVER...DVN AND GRB WHICH
WERE ALONG THE ARCTIC FRONT AT 12Z DROPPED 9 TO 11C BY 00Z.
TODAY THROUGH SUNDAY...UPPER RIDGING SEEN OVER ARIZONA AND UTAH IS
FORECAST TO BUILD EAST INTO THE PLAINS AND EVENTUALLY THE UPPER
MISSISSIPPI RIVER VALLEY BY LATE SUNDAY...DUE TO TROUGHING MOVING
INTO THE ROCKIES AND FOUR CORNERS REGION. THE FORECAST AREA WILL
REMAIN ON THE EAST SIDE OF THE UPPER RIDGING...PROMOTING SUBSIDENCE
AND CONTINUED DRY AIR ADVECTION. HOWEVER...THE BUILDING HEIGHTS IN
CONJUNCTION WITH THE LACK OF SNOW COVER AND PLENTY OF SUN SHOULD
HELP THE ARCTIC AIRMASS MODERATE THIS WEEKEND. 850MB TEMPS REFLECT
THE MODERATING...CLIMBING TO AROUND -12C AT 00Z SUNDAY AND -6C AT
00Z MONDAY. THE DRY AIRMASS IN PLACE SHOULD ALSO PROMOTE GOOD
MIXING. GIVEN 850MB TEMPS TODAY...HIGHS ARE ONLY EXPECTED IN THE MID
TEENS TO AROUND 20. THE BLUSTERY NORTHWEST WIND WILL MAKE IT FEEL
COOLER...THOUGH...WITH WIND CHILLS ONLY CLIMBING TO AROUND ZERO.
PLENTY OF WIND ANTICIPATED TONIGHT GIVEN THE SURFACE RIDGE TAKING A
TRACK TO OUR SOUTHWEST. THIS WIND SHOULD KEEP LOWS MOSTLY IN THE
SINGLE DIGITS ABOVE ZERO. ANTICIPATING WE CAN TACK ON ANOTHER 10
DEGREES OF WARMING FOR SUNDAY GIVEN THE 6C JUMP IN 850MB TEMPS.
REGARDING THE WIND CHILL ADVISORY...VERY MARGINAL CONDITIONS AT
BEST. SINCE IT IS ALREADY UP AND WIND CHILLS ARE AT LEAST IN THE
TEENS BELOW ZERO...FIGURE IT IS NOT WORTH CANCELING.
SUNDAY NIGHT THROUGH MONDAY NIGHT...FOCUS TURNS TO THE TROUGHING
OVER THE WESTERN U.S AT 00Z MONDAY. GOOD MODEL AGREEMENT EXISTS FOR
THIS TROUGHING TO CROSS THE PLAINS ON MONDAY...THEN SHEAR APART
MONDAY NIGHT AS IT CROSSES THE FORECAST AREA AND THROUGH THE OHIO
VALLEY. BEST 500MB HEIGHT FALLS FOR THE FORECAST AREA OCCUR MONDAY
AFTERNOON AND EVENING...RANGING FROM 40 TO 70 METERS PER 12 HOURS...
HIGHEST IN THE FAR SOUTHERN SECTIONS OF THE AREA. SO THE DPVA
FORCING IS FAIRLY DECENT. ISENTROPIC LIFT FIELDS...ON THE OTHER
HAND...ARE TERRIBLE WITH BASICALLY VERY LITTLE IF ANY NET ADIABATIC
OMEGA FROM EITHER THE 11.00Z NAM OR GFS. BEST 850 TO 700MB MOISTURE
TRANSPORT ALSO NOT THAT IMPRESSIVE...MOSTLY FOCUSED IN MISSOURI...
ILLINOIS AND ARKANSAS. SO BASICALLY ALL PRECIPITATION PRODUCTION
WILL COME FROM THE 500MB HEIGHT FALLS ACTING ON THE WEAKER MOISTURE
BEING TRANSPORTED UP INTO THE AREA. CERTAINLY GOOD MODEL AGREEMENT
EXISTS OF PRECIPITATION SPREADING SOUTHWEST TO NORTHEAST ACROSS MUCH
OF THE FORECAST AREA ON MONDAY...ESPECIALLY DURING THE AFTERNOON...
WHICH SEEMS REASONABLE. RAISED PRECIPITATION CHANCES UP A LITTLE
MORE FOR THE AFTERNOON...MAINLY ALONG AND SOUTH OF I-90. THINK THE
11.00Z NAM QPF IS A LITTLE TOO HIGH GIVEN LACK OF ISENTROPIC LIFT
AND STRONGER MOISTURE TRANSPORT. STILL...COULD PICK UP ANYWHERE FROM
A HALF INCH TO TWO INCHES OF SNOW OUT OF THE EVENT...HIGHEST ACROSS
THE SOUTH WHERE THE BETTER FORCING IS. PRECIPITATION SHOULD SLOWLY
DIMINISH MONDAY NIGHT AS THE UPPER TROUGHING SHEARS APART...REDUCING
THE DPVA LIFT. REGARDING TEMPERATURES...WITH THE PRECIPITATION AND
CLOUDS TRENDING SLOWER TO MOVE IN FOR SUNDAY NIGHT INTO MONDAY
MORNING...LOWERED TEMPERATURES A FEW DEGREES SUNDAY NIGHT AND STAYED
WITH A NORMAL DIURNAL TREND. POTENTIAL DOES EXIST MONDAY MORNING FOR
A LITTLE SUN NORTH OF I-94...THUS HIGHS ON MONDAY END UP WARMEST
NORTH OF I-94. SOUTHERLY ADVECTION OF WARM AIR AHEAD OF THE TROUGH
SHOULD RESULT IN HIGHS AGAIN IN THE UPPER 20S TO AROUND 30. WITH
PLENTY OF CLOUDS LINGERING MONDAY NIGHT AND LITTLE IN THE WAY OF
COLD ADVECTION...ANTICIPATING TEMPERATURES TO ONLY DROP AROUND 5
DEGREES.
.LONG TERM...TUESDAY THROUGH FRIDAY NIGHT
249 AM CST SAT FEB 11 2012
LONG TERM FORECAST LOOKS A LITTLE MORE UNCERTAIN TODAY...THOUGH THE
FEATURES SEEN YESTERDAY OF A SPLIT FLOW PATTERN REMAIN. THE BIGGEST
UNCERTAINTY IS WEDNESDAY NIGHT AND THURSDAY. DURING THIS PERIOD...
THE NEW 11.00Z ECMWF SUGGESTS TROUGHING COMING OUT OF THE SOUTHWEST
U.S. AND EVENTUALLY PHASING WITH A NORTHERN STREAM SHORTWAVE TROUGH
NEAR THE FORECAST AREA. THE RESULT WOULD PROBABLY BE AN
ADVISORY-TYPE WET SNOW EVENT FOR THE SOUTHEASTERN HALF OF THE
FORECAST AREA. PROBLEM IS...THE ECMWF IS THE ONLY MODEL SHOWING THIS
PHASING POTENTIAL. THE 11.00Z GFS/UKMET KEEP THE TWO SEPARATED WITH
THE SOUTHWESTERN TROUGH EJECTING FARTHER SOUTH. MEANWHILE...THE
11.00Z CANADIAN HAS MORE FOCUS ON THE NORTHERN STREAM FEATURE AND
PRODUCES A FAIRLY AMPLIFIED TROUGH OVER MINNESOTA ON THURSDAY. THE
11.00Z GFS ENSEMBLES DEPICT A SIMILAR AMOUNT OF UNCERTAINTY.
THEREFORE...FOR NOW FOLLOWED A CONSENSUS BLEND FOR PRECIPITATION
CHANCES WHICH END UP 20-40. PLUS...IT IS HARD TO TRUST PHASING THIS
FAR OUT.
OTHERWISE...PRECIPITATION FROM MONDAY NIGHT SHOULD FOR THE MOST PART
END TUESDAY AS THE LINGERING SHORTWAVE TROUGH FALLS APART. THIS
LEAVES DRY CONDITIONS FOR TUESDAY NIGHT AND WEDNESDAY...WHICH SHOULD
ALSO BE ASSOCIATED WITH SOME SMALL 500MB HEIGHT RISES AND A SURFACE
RIDGE OF HIGH PRESSURE. AFTER WHATEVER HAPPENS WITH THE WEDNESDAY
NIGHT THROUGH THURSDAY TIME PERIOD...GOOD AGREEMENT EXISTS OF A
WEST-NORTHWEST FLOW PATTERN HEADING INTO NEXT WEEKEND WITH HARD TO
TIME SHORTWAVES MOVING THROUGH THE FLOW. GIVEN THAT HIGH PRESSURE
SHOULD DOMINATE ACROSS THE SOUTHERN U.S. IN THE WAKE OF THE THURSDAY
SYSTEM...PREVENTING MOISTURE RETURN FROM THE GULF OF MEXICO FOR A
LITTLE WHILE...KEPT CONDITIONS DRY FOR FRIDAY.
ONE THING THAT DOES LOOK CERTAIN FOR THE LONG TERM PERIOD IS
TEMPERATURES TO REMAIN AT OR ABOVE NORMAL. A BRIEF SHOT OF COOL AIR
MAY COME THROUGH ON THURSDAY WITH 850MB TEMPS FALLING TO -6 TO -8C.
STILL...THIS WOULD BE ABOVE NORMAL. STAYED PRETTY MUCH WITH A BLEND
OF ALL GUIDANCE FOR TEMPERATURES AS IT SEEMS REASONABLE AT THIS
POINT.
&&
.AVIATION...TODAY AND TONIGHT
526 AM CST SAT FEB 11 2012
A TIGHT PRESSURE GRADIENT WILL REMAIN ACROSS THE AREA TODAY.
SUSTAINED NORTHWEST WINDS WILL REMAIN IN THE 15 TO 20 KNOT RANGE
TODAY...AND 10 TO 15 KNOTS TONIGHT. IN ADDITION TO THESE WINDS
WILL GUST TO AROUND 25 KNOTS BETWEEN 11.16Z AND 12.02Z. BOTH
CEILINGS AND VISIBILITIES WILL REMAIN VFR THROUGH THIS TIME PERIOD.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
249 AM CST SAT FEB 11 2012
WI...WIND CHILL ADVISORY UNTIL 9 AM CST THIS MORNING FOR WIZ017-029-
034.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
249 AM CST SAT FEB 11 2012
.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
249 AM CST SAT FEB 11 2012
MAIN FORECAST CONCERN IS ON PRECIPITATION FOR MONDAY
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS
SHOWED TROUGHING COMING INTO CALIFORNIA...RIDGING FROM ARIZONA INTO
SASKATCHEWAN...AND TROUGHING FROM QUEBEC INTO ILLINOIS. THE FORECAST
AREA LIES IN SUBSIDENCE IN THE WAKE OF THE TROUGHING...PROMOTING A
FEED OF DRIER AIR INTO THE FORECAST AREA. 00Z MPX SOUNDING AS WELL
AS A PRECIPITABLE WATER PLOT OF 00Z RAOB DATA ACROSS THE UPPER
MIDWEST REFLECTIVE OF THE DRY AIR...WITH VALUES AROUND 0.05 OF AN
INCH OR 25 PERCENT OF NORMAL. WITH ALL THE DRY AIR...SKIES ARE
CLEAR. ARCTIC AIR SLOWLY FLOWING IN TOO WITH THE DRY AIR ON A
SUSTAINED 10 TO 15 MPH NORTHWEST WIND. TEMPERATURES HAVE FALLEN INTO
THE SINGLE DIGITS ABOVE ZERO. THE LACK OF SNOW COVER AND PERSISTENT
WIND KEEPING TEMPERATURES FROM FALLING MUCH LOWER. COMBINATION OF
THE WIND AND TEMPERATURES RESULTING IN WIND CHILLS MOSTLY IN THE
SINGLE DIGITS OR TEENS BELOW ZERO. AREA OF HIGH PRESSURE ASSOCIATED
WITH THE SUBSIDENCE FAR OFF TO THE WEST...OVER THE DAKOTAS. NO BIG
CHANGE IN 850MB TEMPS FROM 12Z FRI TO 00Z SATURDAY AT BIS...ABR AND
MPX...ALL SITTING BETWEEN -17 AND -20C. HOWEVER...DVN AND GRB WHICH
WERE ALONG THE ARCTIC FRONT AT 12Z DROPPED 9 TO 11C BY 00Z.
TODAY THROUGH SUNDAY...UPPER RIDGING SEEN OVER ARIZONA AND UTAH IS
FORECAST TO BUILD EAST INTO THE PLAINS AND EVENTUALLY THE UPPER
MISSISSIPPI RIVER VALLEY BY LATE SUNDAY...DUE TO TROUGHING MOVING
INTO THE ROCKIES AND FOUR CORNERS REGION. THE FORECAST AREA WILL
REMAIN ON THE EAST SIDE OF THE UPPER RIDGING...PROMOTING SUBSIDENCE
AND CONTINUED DRY AIR ADVECTION. HOWEVER...THE BUILDING HEIGHTS IN
CONJUNCTION WITH THE LACK OF SNOW COVER AND PLENTY OF SUN SHOULD
HELP THE ARCTIC AIRMASS MODERATE THIS WEEKEND. 850MB TEMPS REFLECT
THE MODERATING...CLIMBING TO AROUND -12C AT 00Z SUNDAY AND -6C AT
00Z MONDAY. THE DRY AIRMASS IN PLACE SHOULD ALSO PROMOTE GOOD
MIXING. GIVEN 850MB TEMPS TODAY...HIGHS ARE ONLY EXPECTED IN THE MID
TEENS TO AROUND 20. THE BLUSTERY NORTHWEST WIND WILL MAKE IT FEEL
COOLER...THOUGH...WITH WIND CHILLS ONLY CLIMBING TO AROUND ZERO.
PLENTY OF WIND ANTICIPATED TONIGHT GIVEN THE SURFACE RIDGE TAKING A
TRACK TO OUR SOUTHWEST. THIS WIND SHOULD KEEP LOWS MOSTLY IN THE
SINGLE DIGITS ABOVE ZERO. ANTICIPATING WE CAN TACK ON ANOTHER 10
DEGREES OF WARMING FOR SUNDAY GIVEN THE 6C JUMP IN 850MB TEMPS.
REGARDING THE WIND CHILL ADVISORY...VERY MARGINAL CONDITIONS AT
BEST. SINCE IT IS ALREADY UP AND WIND CHILLS ARE AT LEAST IN THE
TEENS BELOW ZERO...FIGURE IT IS NOT WORTH CANCELING.
SUNDAY NIGHT THROUGH MONDAY NIGHT...FOCUS TURNS TO THE TROUGHING
OVER THE WESTERN U.S AT 00Z MONDAY. GOOD MODEL AGREEMENT EXISTS FOR
THIS TROUGHING TO CROSS THE PLAINS ON MONDAY...THEN SHEAR APART
MONDAY NIGHT AS IT CROSSES THE FORECAST AREA AND THROUGH THE OHIO
VALLEY. BEST 500MB HEIGHT FALLS FOR THE FORECAST AREA OCCUR MONDAY
AFTERNOON AND EVENING...RANGING FROM 40 TO 70 METERS PER 12 HOURS...
HIGHEST IN THE FAR SOUTHERN SECTIONS OF THE AREA. SO THE DPVA
FORCING IS FAIRLY DECENT. ISENTROPIC LIFT FIELDS...ON THE OTHER
HAND...ARE TERRIBLE WITH BASICALLY VERY LITTLE IF ANY NET ADIABATIC
OMEGA FROM EITHER THE 11.00Z NAM OR GFS. BEST 850 TO 700MB MOISTURE
TRANSPORT ALSO NOT THAT IMPRESSIVE...MOSTLY FOCUSED IN MISSOURI...
ILLINOIS AND ARKANSAS. SO BASICALLY ALL PRECIPITATION PRODUCTION
WILL COME FROM THE 500MB HEIGHT FALLS ACTING ON THE WEAKER MOISTURE
BEING TRANSPORTED UP INTO THE AREA. CERTAINLY GOOD MODEL AGREEMENT
EXISTS OF PRECIPITATION SPREADING SOUTHWEST TO NORTHEAST ACROSS MUCH
OF THE FORECAST AREA ON MONDAY...ESPECIALLY DURING THE AFTERNOON...
WHICH SEEMS REASONABLE. RAISED PRECIPITATION CHANCES UP A LITTLE
MORE FOR THE AFTERNOON...MAINLY ALONG AND SOUTH OF I-90. THINK THE
11.00Z NAM QPF IS A LITTLE TOO HIGH GIVEN LACK OF ISENTROPIC LIFT
AND STRONGER MOISTURE TRANSPORT. STILL...COULD PICK UP ANYWHERE FROM
A HALF INCH TO TWO INCHES OF SNOW OUT OF THE EVENT...HIGHEST ACROSS
THE SOUTH WHERE THE BETTER FORCING IS. PRECIPITATION SHOULD SLOWLY
DIMINISH MONDAY NIGHT AS THE UPPER TROUGHING SHEARS APART...REDUCING
THE DPVA LIFT. REGARDING TEMPERATURES...WITH THE PRECIPITATION AND
CLOUDS TRENDING SLOWER TO MOVE IN FOR SUNDAY NIGHT INTO MONDAY
MORNING...LOWERED TEMPERATURES A FEW DEGREES SUNDAY NIGHT AND STAYED
WITH A NORMAL DIURNAL TREND. POTENTIAL DOES EXIST MONDAY MORNING FOR
A LITTLE SUN NORTH OF I-94...THUS HIGHS ON MONDAY END UP WARMEST
NORTH OF I-94. SOUTHERLY ADVECTION OF WARM AIR AHEAD OF THE TROUGH
SHOULD RESULT IN HIGHS AGAIN IN THE UPPER 20S TO AROUND 30. WITH
PLENTY OF CLOUDS LINGERING MONDAY NIGHT AND LITTLE IN THE WAY OF
COLD ADVECTION...ANTICIPATING TEMPERATURES TO ONLY DROP AROUND 5
DEGREES.
.LONG TERM...TUESDAY THROUGH FRIDAY NIGHT
249 AM CST SAT FEB 11 2012
LONG TERM FORECAST LOOKS A LITTLE MORE UNCERTAIN TODAY...THOUGH THE
FEATURES SEEN YESTERDAY OF A SPLIT FLOW PATTERN REMAIN. THE BIGGEST
UNCERTAINTY IS WEDNESDAY NIGHT AND THURSDAY. DURING THIS PERIOD...
THE NEW 11.00Z ECMWF SUGGESTS TROUGHING COMING OUT OF THE SOUTHWEST
U.S. AND EVENTUALLY PHASING WITH A NORTHERN STREAM SHORTWAVE TROUGH
NEAR THE FORECAST AREA. THE RESULT WOULD PROBABLY BE AN
ADVISORY-TYPE WET SNOW EVENT FOR THE SOUTHEASTERN HALF OF THE
FORECAST AREA. PROBLEM IS...THE ECMWF IS THE ONLY MODEL SHOWING THIS
PHASING POTENTIAL. THE 11.00Z GFS/UKMET KEEP THE TWO SEPARATED WITH
THE SOUTHWESTERN TROUGH EJECTING FARTHER SOUTH. MEANWHILE...THE
11.00Z CANADIAN HAS MORE FOCUS ON THE NORTHERN STREAM FEATURE AND
PRODUCES A FAIRLY AMPLIFIED TROUGH OVER MINNESOTA ON THURSDAY. THE
11.00Z GFS ENSEMBLES DEPICT A SIMILAR AMOUNT OF UNCERTAINTY.
THEREFORE...FOR NOW FOLLOWED A CONSENSUS BLEND FOR PRECIPITATION
CHANCES WHICH END UP 20-40. PLUS...IT IS HARD TO TRUST PHASING THIS
FAR OUT.
OTHERWISE...PRECIPITATION FROM MONDAY NIGHT SHOULD FOR THE MOST PART
END TUESDAY AS THE LINGERING SHORTWAVE TROUGH FALLS APART. THIS
LEAVES DRY CONDITIONS FOR TUESDAY NIGHT AND WEDNESDAY...WHICH SHOULD
ALSO BE ASSOCIATED WITH SOME SMALL 500MB HEIGHT RISES AND A SURFACE
RIDGE OF HIGH PRESSURE. AFTER WHATEVER HAPPENS WITH THE WEDNESDAY
NIGHT THROUGH THURSDAY TIME PERIOD...GOOD AGREEMENT EXISTS OF A
WEST-NORTHWEST FLOW PATTERN HEADING INTO NEXT WEEKEND WITH HARD TO
TIME SHORTWAVES MOVING THROUGH THE FLOW. GIVEN THAT HIGH PRESSURE
SHOULD DOMINATE ACROSS THE SOUTHERN U.S. IN THE WAKE OF THE THURSDAY
SYSTEM...PREVENTING MOISTURE RETURN FROM THE GULF OF MEXICO FOR A
LITTLE WHILE...KEPT CONDITIONS DRY FOR FRIDAY.
ONE THING THAT DOES LOOK CERTAIN FOR THE LONG TERM PERIOD IS
TEMPERATURES TO REMAIN AT OR ABOVE NORMAL. A BRIEF SHOT OF COOL AIR
MAY COME THROUGH ON THURSDAY WITH 850MB TEMPS FALLING TO -6 TO -8C.
STILL...THIS WOULD BE ABOVE NORMAL. STAYED PRETTY MUCH WITH A BLEND
OF ALL GUIDANCE FOR TEMPERATURES AS IT SEEMS REASONABLE AT THIS
POINT.
&&
.AVIATION...THROUGH 06Z SUNDAY
1100 PM CST FRI FEB 10 2012
A TIGHT PRESSURE GRADIENT ON THE EAST SIDE OF AN AREA OF HIGH
PRESSURE OVER THE NORTHERN PLAINS WILL KEEP WINDS UP FROM THE
NORTH-NORTHWEST FOR THE REST OF TONIGHT AND THROUGH MUCH OF SAT.
MOMENTUM TRANSFER VIA BUFKIT SOUNDINGS SUGGEST GUSTS UPWARD OF 20 TO
25 KTS. WOULDN/T BE SURPRISED IF THEY ARE SLIGHTLY HIGHER AT KRST.
THE WINDS WILL WEAKEN BY SUNDOWN SAT...ALTHOUGH LIKELY STILL BE NEAR
10 KTS.
OTHERWISE...VFR CONDITIONS WILL CONTINUE AS THE HIGH PRESSURE
INFLUENCES THE REGION INTO SUNDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
249 AM CST SAT FEB 11 2012
WI...WIND CHILL ADVISORY UNTIL 9 AM CST THIS MORNING FOR WIZ017-029-
034.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
257 AM CST MON FEB 13 2012
.SHORT TERM...TODAY THROUGH THURSDAY
257 AM CST MON FEB 13 2012
MAIN FORECAST CONCERNS ARE ON SNOW FOR TODAY AND TONIGHT...THEN A
SYSTEM TO WATCH FOR WEDNESDAY THROUGH THURSDAY.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS
SHOWED RIDGING OVER SOUTH CENTRAL CANADA...SHORTWAVE TROUGHING
DROPPING INTO NORTHERN CALIFORNIA...A BROAD TROUGH ACROSS THE
CENTRAL AND SOUTHERN PLAINS...AND RIDGING UP AND DOWN THE
MISSISSIPPI RIVER VALLEY. THE FORECAST AREA REMAINS IN SUBSIDENCE
UNDER THE UPPER RIDGE...AS WELL AS IN AN AXIS OF DRY AIR ASSOCIATED
WITH A RIDGE OF HIGH PRESSURE AT THE SURFACE. A LAPS SOUNDING OVER
LA CROSSE AT 08Z DEPICTED A VERY DRY SOUNDING WITH PRECIPITABLE
WATER VALUE OF 0.08 INCHES. THIS DRY AIR KEPT SKIES MAINLY CLEAR IN
THE EVENING...BUT NOW MID LEVEL CLOUDS ARE STREAMING TO AREAS WEST
OF THE MISSISSIPPI RIVER. OAX 00Z RAOB AND 04Z TAMDAR SOUNDING
SHOWED A SATURATED LAYER BETWEEN 725-825MB...REFLECTING THE MID
LEVEL CLOUDS. RADAR LOOP AND SURFACE OBS SHOW THE EASTERN EDGE OF
PRECIPITATION...ASSOCIATED WITH MOISTURE TRANSPORT AND DPVA AHEAD OF
THE CENTRAL PLAINS TROUGH...NOW INTO WESTERN IOWA. PRECIPITABLE WATER
VALUES DEFINITELY HIGHER OVER THE CENTRAL PLAINS...THANKS TO A
SOUTHERLY LOW LEVEL JET OUT OF THE GULF OF MEXICO. 00Z RAOBS SHOWED
VALUES BETWEEN 0.4 AND 0.5 INCHES AT DDC...OUN AND AMA.
TODAY AND TONIGHT...TROUGHING OVER THE CENTRAL AND SOUTHERN PLAINS
IS PROGGED TO CONTINUE TRACKING EASTWARD THROUGH TONIGHT...MOVING
THROUGH THE OHIO VALLEY AND SORT OF SHEARING OUT AS IT TRIES TO GET
THROUGH THE RIDGING. AS A RESULT...FORCING FOR THIS TROUGH IS
STRONGEST TODAY AND THEN WEAKENS TONIGHT. 500MB HEIGHT FALLS IN 12
HOURS PROGGED BETWEEN 50-70 METERS OVER THE FORECAST AREA...GREATEST
BETWEEN 18-06Z. THEREFORE...JUST FROM FORCING THIS LOOKS TO BE THE
BEST POTENTIAL FOR PRECIPITATION. MOISTURE TRANSPORT AND ISENTROPIC
LIFT PLOTS STILL LOOK TERRIBLE IN TERMS OF THIS KIND OF FORCING...
WITH MOST OF IT FOCUSED SOUTH OF I-80. STILL...THE HEIGHT FALLS
ACTING ON THE MOISTURE BEING BROUGHT UP OUT OF THE GULF OF MEXICO
SHOULD BE ENOUGH TO SPREAD LIGHT SNOW ACROSS THE AREA. TIMING VARIES
ON MODEL...LIKELY DUE TO UNCERTAINTY ON HOW FAST THE DRY AIR CAN
ERODE. THE 13.00Z GFS AND 12.21Z SREF MEANS ARE FASTEST SPREADING IT
NORTHEAST...WHILE THE 13.00Z NAM/ECMWF ARE A LITTLE SLOWER. IN FACT
IN THIS LATTER GROUP...THEY KEEP PRECIPITATION ENTIRELY ALONG AND
SOUTH OF I-94 BEFORE 00Z. FOR NOW STAYED WITH A COMPROMISE...IN
AGREEMENT WITH THE LATEST HRRR RUNS WHICH HAVE BEEN DOING WELL THUS
FAR. THIS RESULTS IN THE FORECAST ENDING UP PRETTY SIMILAR TO WHAT
HAS BEEN FORECAST THE PAST FEW DAYS FOR PRECIPITATION CHANCES. SNOW
STILL LOOKS TO DIMINISH AFTER 06Z AS THE TROUGH WEAKENS AND MOVES
EAST OF THE AREA. VERY GOOD MODEL AGREEMENT ON QPF TODAY AND LOOKS
REASONABLE GIVEN HEIGHT FALLS THE ONLY FORCING. TOTAL SNOWFALL
AMOUNTS STILL LOOKING IN THAT 0.5-2 INCH RANGE WITH SNOW TO WATER
RATIOS BETWEEN 10-15 TO 1. HIGHEST SNOW AMOUNTS SOUTH OF I-90. ON A
PRECIPITATION TYPE SIDE NOTE...THERE ARE SOME HINTS THIS EVENING OF
A POSSIBLE LOSS OF ICE IN THE GRANT COUNTY AREA. HARD TO SAY WITH
THE MOISTURE INTERSECTING AT -10/-11C...WHICH SHOULD BE ABLE TO KEEP
IT AS SNOW...SO NO FREEZING DRIZZLE MENTIONED AT THIS TIME.
REGARDING CLOUD COVER...SHOULD SEE CLOUDS SPREAD NORTHEAST ACROSS
THE AREA THIS MORNING...THEN STAY IN PLACE THROUGH TONIGHT. THESE
CLOUDS WILL LIMIT TEMPERATURE FALL TONIGHT GIVEN LACK OF COLD
ADVECTION...PROBABLY ONLY FALLING ABOUT 5 DEGREES FROM TODAYS
HIGHS. AS FOR TODAYS HIGHS...INCREASING SOUTHERLY FLOW WILL ADVECT
WARMER AIR INTO THE AREA. A BLEND OF GUIDANCE SEEMS REASONABLE.
TUESDAY AND TUESDAY NIGHT...IN THE WAKE OF TODAY AND TONIGHTS
TROUGH...MODELS SHOW ANOTHER WEAK SHORTWAVE CROSSING THE FORECAST
AREA TUESDAY EVENING. THIS SHORTWAVE CAN BE SEEN ON WATER VAPOR OVER
NORTH DAKOTA. VERY LITTLE GOING ON WITH IT AND MODELS SUGGEST THE
SAME WHEN IT COMES ACROSS. PLUS...THE SHORTWAVE DOES NOT HAVE MUCH
FORCING OR MOISTURE TO WORK WITH. THEREFORE...THE DRY FORECAST
DURING THIS PERIOD STILL SEEMS REASONABLE. CLOUDS SHOULD TAKE AWHILE
CLEARING...THOUGH...DUE TO A LACK OF ANY STRONG SUBSIDENCE. THERE IS
A WESTERLY WIND PUSH OF SOME DRIER AIR FROM THE PLAINS ON
TUESDAY...BUT THERE ARE HINTS THAT COME TUESDAY EVENING A SURGE OF
800-900MB MOISTURE LIKELY WITH THE SHORTWAVE MOVES IN. THEREFORE
HAVE INCREASED CLOUD COVER. THIS PUTS A CONCERN ON TEMPERATURES. A
SOUTHWEST WIND ON TUESDAY BRINGING IN SOME WARMER AIR SHOULD HELP
TEMPERATURES CLIMB INTO THE LOW TO MID 30S. OF COURSE...IF SUN DOES
DEVELOP...READINGS COULD TOUCH 40. WITH THE IDEA OF MORE CLOUDS
PRESENT TUESDAY NIGHT...DID RAISE LOWS A COUPLE DEGREES.
WEDNESDAY THROUGH THURSDAY...THIS TIME PERIOD HAS BECOME A LITTLE
MORE INTERESTING THIS 13.00Z MODEL CYCLE. A SECOND SHORTWAVE
TROUGH...WHICH IS SEEN RIGHT NOW DIGGING INTO CALIFORNIA...IS
PROGGED TO LIFT NORTHEAST OUT OF THE SOUTHWEST AND EVENTUALLY INTO
LOWER MICHIGAN OR OHIO BY THURSDAY. WITH THIS SHORTWAVE TROUGH
MODELS SHOW A DECENT LOW PRESSURE AREA LIFTING NORTHEAST WITH IT. ON
THE NORTH SIDE IS THE TYPICAL DEFORMATION ZONE OF PRECIPITATION. HOW
FAR NORTH THE SHORTWAVE TROUGH LIFTS AND DEEPENS DEPENDS ON TIMING
AND DISTANCE FROM A NORTHERN STREAM TYPE SHORTWAVE TROUGH DIGGING
INTO THE DAKOTAS. IF THESE TWO CAN MEET UP...WHICH HAS BEEN SHOWN
THE PAST FEW DAYS FROM THE CANADIAN AND SOME ECMWF RUNS...THEN THE
LOW PRESSURE AREA LIFTS FARTHER NORTH. WE COULD BE DEALING WITH AN
ADVISORY TYPE SNOWFALL...AND POSSIBLY RAIN MIXING IN FOR SOME
SOUTHERN LOCATIONS. ON THE OTHER HAND...IF THEY DO NOT MEET UP WHICH
HAS BEEN SHOWN BY SOME PAST GFS/ECMWF RUNS...THE SYSTEM STAYS SOUTH
AND THE FORECAST AREA IS DRY. CERTAINLY TREND IN THE 13.00Z MODEL
CYCLE HAS BEEN FARTHER NORTH AND FASTER...SO HAVE ADJUSTED THE
FORECAST THIS WAY. DID NOT GO COMPLETELY WITH THE 13.00Z
GFS/ECMWF/CANADIAN...THOUGH...BECAUSE THE GFS ENSEMBLES STILL SHOW
QUITE A BIT OF SPREAD. PLUS...MODEL CONSISTENCY HAS NOT BEEN THE
BEST. CHANGES THIS FORECAST INCLUDE BRINGING LOW PRECIPITATION
CHANCES INTO NORTHEAST IOWA WEDNESDAY AFTERNOON...RAISING CHANCES
10-20 PERCENT WEDNESDAY NIGHT...THEN ENDING MOST OF THE
PRECIPITATION FOR THURSDAY AFTERNOON. AN ADDITIONAL CHANGE IS
RAISING LOWS 3-5 DEGREES WEDNESDAY NIGHT...BUT THESE ARE TRICKY. IF
MORE SUN IS OBSERVED WEDNESDAY...THE LOWS MAY NEED TO BE RAISED
FURTHER. THE SAME WOULD OCCUR WITH A FARTHER NORTH TRACK. NEEDLESS
TO SAY...A LOT TO BE IRONED OUT.
.LONG TERM...THURSDAY NIGHT THROUGH SUNDAY NIGHT
257 AM CST MON FEB 13 2012
13.00Z ECMWF/CANADIAN/GFS AND GFS ENSEMBLES REMAIN IN DISAGREEMENT
ON A LOT OF THE LONG TERM PERIOD WITH REGARDS TO INDIVIDUAL
SHORTWAVE DETAILS. AGAIN...THIS IS PROBABLY RELATED TO FAST...ZONAL
PACIFIC FLOW RUNNING INTO A SPLIT FLOW PATTERN OVER NORTH AMERICA.
STILL...DESPITE THE DIFFERENCES...THERE IS GOOD AGREEMENT THAT THE
GULF OF MEXICO WILL BE CUT-OFF FROM BRINGING MOISTURE BACK NORTHWARD
UNTIL SOMETIME EARLY NEXT WEEK. THE MOISTURE CUT-OFF IS DUE TO THE
WEDNESDAY NIGHT/THURSDAY SYSTEM...WHICH ALLOWS A DRIER HIGH PRESSURE
AREA TO MOVE DOWN TO THE GULF COAST. THEREFORE...THE ENTIRE LONG
TERM FORECAST REMAINS DRY. 850MB TEMPS ARE HINTED TO BE SLIGHTLY
COOLER FOR FRIDAY AND SATURDAY COMPARED TO THE PREVIOUS
FORECAST...DUE TO SOME SEMI-DECENT AGREEMENT ON NORTHERN STREAM
TROUGHING AFFECTING THE FORECAST AREA DURING THIS TIME.
HOWEVER...READINGS ARE STILL LIKELY TO END UP AT OR ABOVE NORMAL FOR
HIGHS AND LOWS WITH A LOT OF THE COLD AIR STAYING WELL NORTH INTO
CANADA. NO REAL STRONG WARM SURGES EITHER DUE TO THE SPLIT FLOW
PATTERN.
&&
.AVIATION...THROUGH 06Z TUESDAY
1120 PM CST SUN FEB 12 2012
CLOUDS WILL INCREASE OVERNIGHT...LOWERING INTO MVFR RANGE AROUND
18Z. -SN WILL ACCOMPANY THE LOW CIGS FOR THE AFTERNOON...AND A
PERIOD OF 2SM LOOKS PROBABLE FROM MID AFTERNOON INTO EARLY EVENING.
STILL...OVERALL ACCUMULATIONS WILL BE MINOR AT THE TAF
SITES...EXPECTED TO STAY BELOW AN INCH.
THE LOW MVFR CIGS WILL PERSIST THROUGH MON NIGHT AS THE RESPONSIBLE
UPPER LEVEL TROUGH EXITS EAST. -SN WILL LIKELY LINGER INTO THE
OVERNIGHT HOURS...BUT THERE SHOULD BE IMPROVEMENT IN THE VSBYS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
257 AM CST MON FEB 13 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS PUEBLO CO
353 AM MST MON FEB 13 2012
.SHORT TERM...
(TODAY AND TONIGHT)
CURRENTLY...SATELLITE IMAGERY INDICATES AN UPPER LEVEL TROUGH
LIFTING NORTHEAST ACROSS EASTERN COLORADO EARLY THIS MORNING. AREA
OBSERVATIONS ARE INDICATING A FEW AREAS OF PATCHY FOG OVER PUEBLO
AND EL PASO COUNTIES. WHERE FOG IS OCCURRING...IT CAN BE DENSE SO
CAUTION IS ADVISED WHEN FOG IS ENCOUNTERED. BESIDES FOG...LIGHT
SNOW CONTINUES ALONG THE CONTINENTAL DIVIDE WITH THE CENTRAL
MOUNTAINS FAVORED IN THE NORTHWEST FLOW. RADAR IS INDICATING LIGHT
SNOW OVER THE EASTERN MOUNTAINS AS WELL. A FEW ECHOES ARE ALSO
SHOWING UP OVER KIOWA COUNTY...BUT THIS IS LIKELY NOT REACHING THE
GROUND AT THIS TIME.
TODAY...THE UPPER LEVEL TROUGH WILL CONTINUE EAST INTO KANSAS
THROUGH THIS AFTERNOON WITH NORTHWESTERLY FLOW REMAINING ENTRENCHED
ACROSS THE REGION. THIS WILL LEAD TO CONTINUED LIGHT SNOW FOR THE
CONTINENTAL DIVIDE...ESPECIALLY OVER THE CENTRAL MOUNTAINS. ANY
ADDITIONAL ACCUMULATIONS TODAY WILL TOTAL 2 TO 4 INCHES WITH THE
HIGHEST AMOUNTS OVER THE CENTRAL MOUNTAINS. THE TROUBLE SPOT FOR
THIS AFTERNOON LOOKS LIKE TELLER COUNTY. THE GFS AND NAM ARE
PRINTING OUT A PERIOD OF LIGHT SNOWFALL OVER TELLER COUNTY THIS
AFTERNOON WHILE THE HIGHER RESOLUTION WRF RUNS AND HRRR KEEP THE
AREA DRY. KEPT LOW POPS OVER TELLER COUNTY FOR LATE THIS AFTERNOON
AND THIS EVENING TO ACCOUNT FOR THE LOW CHANCES THERE. ANY SNOWFALL
WILL BE LIGHT WITH ONLY AN INCH OR TWO POSSIBLE. TEMPERATURES TODAY
WILL BE THE OTHER ISSUE. GUIDANCE CAME IN VERY WARM...HIGHS WELL
INTO THE 50S. GIVEN THE CLOUD COVER AND HIGH RES MODELS PROJECTING
WEAK NORTH TO EASTERLY FLOW FOR THE NORTHERN HALF OF THE
PLAINS...HAVE A FEELING HIGHS WILL BE MUCH COOLER THAN THIS. FOR
NOW HAVE HIGHS GENERALLY IN THE LOWER TO MID 40S FOR THE PLAINS.
THE EXCEPTION WILL LIKELY BE ALONG THE LEE SLOPES OF THE EASTERN
MOUNTAINS WHERE DOWNSLOPE WILL LIKELY ADD A FEW DEGREES TO THE HIGHS.
TONIGHT...HIGH PRESSURE WILL BUILD ACROSS THE REGION AHEAD OF THE
NEXT STORM SYSTEM WHICH IS FORECAST TO DIG ACROSS THE GREAT BASIN.
LIGHT SNOW WILL CONTINUE ALONG THE CONTINENTAL DIVIDE AND LIKELY
INCREASE SOME TOWARDS TUESDAY MORNING AS FLOW TRANSITIONS TO
SOUTHWESTERLY. LOWS WILL BE IN THE LOWER 20S FOR MUCH OF THE
REGION. MOZLEY
.LONG TERM...
(TUESDAY THROUGH MONDAY)
...TUES/WED WX SYSTEM A BIT WEAKER...
LATEST SIMULATIONS HAVE BACKED OFF A BIT ON THE INTENSITY OF THE WX
SYSTEM THAT WILL TRACK ACROSS THE REGION DURING THE TUE/WED TIME PD.
SIMULATIONS ARE NOW A BIT FARTHER SOUTH AND NOT AS "WRAPPED UP" AS
THEY WERE 24H AGO. WE WILL STILL LIKELY SEE SNOWS ALONG THE
CONTDVD BUT THE PRECIP ON THE PLAINS...ESPECIALLY THE PALMER
DVD...LOOKS TO BE QUITE A BIT LESS. FOR NOW HAVE KEPT HIGH POPS
ALONG THE CONTDVD STARTING TOMORROW AFTERNOON AND LASTING THROUGH
THE NIGHT. IT APPEARS THAT THE HEAVIEST SNOW WILL LIKELY FALL ON
THE SW FACING SLOPES OF THE SAN JUANS WERE UP TO A FOOT WILL BE
POSSIBLE. WINTER WX HILITES WILL LIKELY BE NEEDED FOR THIS REGION
LATER TODAY.
PRECIPITATION WILL LIKELY DEVELOP OVER THE PIKES PEAK REGION LATE
TUESDAY NIGHT AND DECREASE BY WED AFTERNOON. THE HEAVY SNOW WHICH
WAS FCST 24H AGO FOR THIS REGION HAS BACKED OFF CONSIDERABLY...AND
NOW IT LOOKS LIKE AMOUNTS WILL BE IN THE 1 TO 2" AMOUNTS...IF
THAT.
LOOKING AT THE REST OF THE FCST...IT STILL APPEARS MOST AREAS WILL
BE DRY FROM THU INTO EARLY NEXT WEEK. THE EXCEPTION WILL BE ALONG
THE CONTDVD WERE OCCNL SNOW SHOWERS WILL BE POSSIBLE THROUGHOUT
THE PERIOD.
TEMPS THROUGH THE PERIOD WILL STAY ON THE COOL SIDE...WITH MAINLY
40S OVER THE PLAINS AND 20S AND 30S IN THE MTNS. OCCNL MAINLY DRY
COOL FRONTS WILL MOVE ACROSS THE PLAINS IN THE NW FLOW ALOFT.
/HODANISH
&&
.AVIATION...
KPUB...PATCHY FOG HAVE DEVELOPED THIS MORNING AROUND THE KPUB
TERMINAL AND HAVE LOWERED VIS TO MVFR. FOG SHOULD DIMINISH AND VFR
CONDITIONS WILL PREVAIL BY 13Z THIS MORNING. MODELS HINTING AT FOG
DEVELOPING AGAIN TONIGHT AFTER AROUND 04Z.
KALS...CURRENT OBSERVATIONS INDICATE LOW CLOUDS HAVE DEVELOPED OVER
THE TERMINAL WITH CIGS LOWERING TO 500 FEET. EXPECT THESE LOW CIGS
THROUGH THE NEXT SEVERAL HOURS WITH IMPROVING CONDITIONS BY 16Z.
EXPECT VFR CONDITIONS ONCE THE LOW STRATUS DISSIPATE.
KCOS...EXPECT VFR CONDITIONS THROUGH TONIGHT. MOZLEY
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 11 AM MST THIS MORNING FOR
COZ058>060-066.
WINTER STORM WARNING UNTIL 11 AM MST THIS MORNING FOR COZ068.
&&
$$
88/34
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
943 AM CST MON FEB 13 2012
.DISCUSSION...FORECAST CHALLENGE FOR UPDATE CONCERNS CLOUD TRENDS
AND TEMPERATURES. TWO AREAS OF CLOUD COVER OF INTEREST TODAY. MID
LEVEL CLOUDS ASSOCIATED WITH UPPER LOW ACROSS NW CORNER OF ND TO
DRIFT EASTWARD TODAY BUT NOT LIKELY TO HAVE A SIGNIFICANT IMPACT ON
TEMPERATURES. THE OTHER AREA IS THE NORTHERN FRINGE OF A CLOUD
SHIELD ACROSS SE FA FROM CENTRAL PLAINS SYSTEM. RUC SEEMS TO HAVE A
GOOD HANDLE ON CLOUD TRENDS EXPANDING CLOUDS NORTHWARD ACROSS FAR
EASTERN FA WHILE WHOLE CLOUD SHIELD PROPAGATES SLOWLY EAST. SO WITH
CLOUDS HOLDING LONGER ACROSS FAR E-SE FA WILL NEED TO LOWER
TEMPERATURES A COUPLE OF DEGREES. OTHERWISE MAXIMUM VALUES LOOK GOOD
AS TEMPERATURES SHOULD RECOVER TO AT OR A LITTLE WARMER THAN
YESTERDAY MAXIMUMS WITH WARMER START...SOLAR AND CONTINUED WEAK WARM
ADVECTION ALTHOUGH MIXING WILL BE LIGHT. WILL MAKE MINOR ADJUSTMENTS
TO CLOUD COVER OTHERWISE FORECAST IN GOOD SHAPE.
&&
.AVIATION...VFR CONDITIONS WILL CONTINUE THROUGH THE PERIOD. COULD
BE SOME MID-LEVEL (10KFT) CIGS TODAY WITH LOWER VFR CIGS ACROSS MN
LAKES COUNTRY.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
VOELKER
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
548 AM CST MON FEB 13 2012
.SHORT TERM...TODAY THROUGH THURSDAY
257 AM CST MON FEB 13 2012
MAIN FORECAST CONCERNS ARE ON SNOW FOR TODAY AND TONIGHT...THEN A
SYSTEM TO WATCH FOR WEDNESDAY THROUGH THURSDAY.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS
SHOWED RIDGING OVER SOUTH CENTRAL CANADA...SHORTWAVE TROUGHING
DROPPING INTO NORTHERN CALIFORNIA...A BROAD TROUGH ACROSS THE
CENTRAL AND SOUTHERN PLAINS...AND RIDGING UP AND DOWN THE
MISSISSIPPI RIVER VALLEY. THE FORECAST AREA REMAINS IN SUBSIDENCE
UNDER THE UPPER RIDGE...AS WELL AS IN AN AXIS OF DRY AIR ASSOCIATED
WITH A RIDGE OF HIGH PRESSURE AT THE SURFACE. A LAPS SOUNDING OVER
LA CROSSE AT 08Z DEPICTED A VERY DRY SOUNDING WITH PRECIPITABLE
WATER VALUE OF 0.08 INCHES. THIS DRY AIR KEPT SKIES MAINLY CLEAR IN
THE EVENING...BUT NOW MID LEVEL CLOUDS ARE STREAMING TO AREAS WEST
OF THE MISSISSIPPI RIVER. OAX 00Z RAOB AND 04Z TAMDAR SOUNDING
SHOWED A SATURATED LAYER BETWEEN 725-825MB...REFLECTING THE MID
LEVEL CLOUDS. RADAR LOOP AND SURFACE OBS SHOW THE EASTERN EDGE OF
PRECIPITATION...ASSOCIATED WITH MOISTURE TRANSPORT AND DPVA AHEAD OF
THE CENTRAL PLAINS TROUGH...NOW INTO WESTERN IOWA. PRECIPITABLE WATER
VALUES DEFINITELY HIGHER OVER THE CENTRAL PLAINS...THANKS TO A
SOUTHERLY LOW LEVEL JET OUT OF THE GULF OF MEXICO. 00Z RAOBS SHOWED
VALUES BETWEEN 0.4 AND 0.5 INCHES AT DDC...OUN AND AMA.
TODAY AND TONIGHT...TROUGHING OVER THE CENTRAL AND SOUTHERN PLAINS
IS PROGGED TO CONTINUE TRACKING EASTWARD THROUGH TONIGHT...MOVING
THROUGH THE OHIO VALLEY AND SORT OF SHEARING OUT AS IT TRIES TO GET
THROUGH THE RIDGING. AS A RESULT...FORCING FOR THIS TROUGH IS
STRONGEST TODAY AND THEN WEAKENS TONIGHT. 500MB HEIGHT FALLS IN 12
HOURS PROGGED BETWEEN 50-70 METERS OVER THE FORECAST AREA...GREATEST
BETWEEN 18-06Z. THEREFORE...JUST FROM FORCING THIS LOOKS TO BE THE
BEST POTENTIAL FOR PRECIPITATION. MOISTURE TRANSPORT AND ISENTROPIC
LIFT PLOTS STILL LOOK TERRIBLE IN TERMS OF THIS KIND OF FORCING...
WITH MOST OF IT FOCUSED SOUTH OF I-80. STILL...THE HEIGHT FALLS
ACTING ON THE MOISTURE BEING BROUGHT UP OUT OF THE GULF OF MEXICO
SHOULD BE ENOUGH TO SPREAD LIGHT SNOW ACROSS THE AREA. TIMING VARIES
ON MODEL...LIKELY DUE TO UNCERTAINTY ON HOW FAST THE DRY AIR CAN
ERODE. THE 13.00Z GFS AND 12.21Z SREF MEANS ARE FASTEST SPREADING IT
NORTHEAST...WHILE THE 13.00Z NAM/ECMWF ARE A LITTLE SLOWER. IN FACT
IN THIS LATTER GROUP...THEY KEEP PRECIPITATION ENTIRELY ALONG AND
SOUTH OF I-94 BEFORE 00Z. FOR NOW STAYED WITH A COMPROMISE...IN
AGREEMENT WITH THE LATEST HRRR RUNS WHICH HAVE BEEN DOING WELL THUS
FAR. THIS RESULTS IN THE FORECAST ENDING UP PRETTY SIMILAR TO WHAT
HAS BEEN FORECAST THE PAST FEW DAYS FOR PRECIPITATION CHANCES. SNOW
STILL LOOKS TO DIMINISH AFTER 06Z AS THE TROUGH WEAKENS AND MOVES
EAST OF THE AREA. VERY GOOD MODEL AGREEMENT ON QPF TODAY AND LOOKS
REASONABLE GIVEN HEIGHT FALLS THE ONLY FORCING. TOTAL SNOWFALL
AMOUNTS STILL LOOKING IN THAT 0.5-2 INCH RANGE WITH SNOW TO WATER
RATIOS BETWEEN 10-15 TO 1. HIGHEST SNOW AMOUNTS SOUTH OF I-90. ON A
PRECIPITATION TYPE SIDE NOTE...THERE ARE SOME HINTS THIS EVENING OF
A POSSIBLE LOSS OF ICE IN THE GRANT COUNTY AREA. HARD TO SAY WITH
THE MOISTURE INTERSECTING AT -10/-11C...WHICH SHOULD BE ABLE TO KEEP
IT AS SNOW...SO NO FREEZING DRIZZLE MENTIONED AT THIS TIME.
REGARDING CLOUD COVER...SHOULD SEE CLOUDS SPREAD NORTHEAST ACROSS
THE AREA THIS MORNING...THEN STAY IN PLACE THROUGH TONIGHT. THESE
CLOUDS WILL LIMIT TEMPERATURE FALL TONIGHT GIVEN LACK OF COLD
ADVECTION...PROBABLY ONLY FALLING ABOUT 5 DEGREES FROM TODAYS
HIGHS. AS FOR TODAYS HIGHS...INCREASING SOUTHERLY FLOW WILL ADVECT
WARMER AIR INTO THE AREA. A BLEND OF GUIDANCE SEEMS REASONABLE.
TUESDAY AND TUESDAY NIGHT...IN THE WAKE OF TODAY AND TONIGHTS
TROUGH...MODELS SHOW ANOTHER WEAK SHORTWAVE CROSSING THE FORECAST
AREA TUESDAY EVENING. THIS SHORTWAVE CAN BE SEEN ON WATER VAPOR OVER
NORTH DAKOTA. VERY LITTLE GOING ON WITH IT AND MODELS SUGGEST THE
SAME WHEN IT COMES ACROSS. PLUS...THE SHORTWAVE DOES NOT HAVE MUCH
FORCING OR MOISTURE TO WORK WITH. THEREFORE...THE DRY FORECAST
DURING THIS PERIOD STILL SEEMS REASONABLE. CLOUDS SHOULD TAKE AWHILE
CLEARING...THOUGH...DUE TO A LACK OF ANY STRONG SUBSIDENCE. THERE IS
A WESTERLY WIND PUSH OF SOME DRIER AIR FROM THE PLAINS ON
TUESDAY...BUT THERE ARE HINTS THAT COME TUESDAY EVENING A SURGE OF
800-900MB MOISTURE LIKELY WITH THE SHORTWAVE MOVES IN. THEREFORE
HAVE INCREASED CLOUD COVER. THIS PUTS A CONCERN ON TEMPERATURES. A
SOUTHWEST WIND ON TUESDAY BRINGING IN SOME WARMER AIR SHOULD HELP
TEMPERATURES CLIMB INTO THE LOW TO MID 30S. OF COURSE...IF SUN DOES
DEVELOP...READINGS COULD TOUCH 40. WITH THE IDEA OF MORE CLOUDS
PRESENT TUESDAY NIGHT...DID RAISE LOWS A COUPLE DEGREES.
WEDNESDAY THROUGH THURSDAY...THIS TIME PERIOD HAS BECOME A LITTLE
MORE INTERESTING THIS 13.00Z MODEL CYCLE. A SECOND SHORTWAVE
TROUGH...WHICH IS SEEN RIGHT NOW DIGGING INTO CALIFORNIA...IS
PROGGED TO LIFT NORTHEAST OUT OF THE SOUTHWEST AND EVENTUALLY INTO
LOWER MICHIGAN OR OHIO BY THURSDAY. WITH THIS SHORTWAVE TROUGH
MODELS SHOW A DECENT LOW PRESSURE AREA LIFTING NORTHEAST WITH IT. ON
THE NORTH SIDE IS THE TYPICAL DEFORMATION ZONE OF PRECIPITATION. HOW
FAR NORTH THE SHORTWAVE TROUGH LIFTS AND DEEPENS DEPENDS ON TIMING
AND DISTANCE FROM A NORTHERN STREAM TYPE SHORTWAVE TROUGH DIGGING
INTO THE DAKOTAS. IF THESE TWO CAN MEET UP...WHICH HAS BEEN SHOWN
THE PAST FEW DAYS FROM THE CANADIAN AND SOME ECMWF RUNS...THEN THE
LOW PRESSURE AREA LIFTS FARTHER NORTH. WE COULD BE DEALING WITH AN
ADVISORY TYPE SNOWFALL...AND POSSIBLY RAIN MIXING IN FOR SOME
SOUTHERN LOCATIONS. ON THE OTHER HAND...IF THEY DO NOT MEET UP WHICH
HAS BEEN SHOWN BY SOME PAST GFS/ECMWF RUNS...THE SYSTEM STAYS SOUTH
AND THE FORECAST AREA IS DRY. CERTAINLY TREND IN THE 13.00Z MODEL
CYCLE HAS BEEN FARTHER NORTH AND FASTER...SO HAVE ADJUSTED THE
FORECAST THIS WAY. DID NOT GO COMPLETELY WITH THE 13.00Z
GFS/ECMWF/CANADIAN...THOUGH...BECAUSE THE GFS ENSEMBLES STILL SHOW
QUITE A BIT OF SPREAD. PLUS...MODEL CONSISTENCY HAS NOT BEEN THE
BEST. CHANGES THIS FORECAST INCLUDE BRINGING LOW PRECIPITATION
CHANCES INTO NORTHEAST IOWA WEDNESDAY AFTERNOON...RAISING CHANCES
10-20 PERCENT WEDNESDAY NIGHT...THEN ENDING MOST OF THE
PRECIPITATION FOR THURSDAY AFTERNOON. AN ADDITIONAL CHANGE IS
RAISING LOWS 3-5 DEGREES WEDNESDAY NIGHT...BUT THESE ARE TRICKY. IF
MORE SUN IS OBSERVED WEDNESDAY...THE LOWS MAY NEED TO BE RAISED
FURTHER. THE SAME WOULD OCCUR WITH A FARTHER NORTH TRACK. NEEDLESS
TO SAY...A LOT TO BE IRONED OUT.
.LONG TERM...THURSDAY NIGHT THROUGH SUNDAY NIGHT
257 AM CST MON FEB 13 2012
13.00Z ECMWF/CANADIAN/GFS AND GFS ENSEMBLES REMAIN IN DISAGREEMENT
ON A LOT OF THE LONG TERM PERIOD WITH REGARDS TO INDIVIDUAL
SHORTWAVE DETAILS. AGAIN...THIS IS PROBABLY RELATED TO FAST...ZONAL
PACIFIC FLOW RUNNING INTO A SPLIT FLOW PATTERN OVER NORTH AMERICA.
STILL...DESPITE THE DIFFERENCES...THERE IS GOOD AGREEMENT THAT THE
GULF OF MEXICO WILL BE CUT-OFF FROM BRINGING MOISTURE BACK NORTHWARD
UNTIL SOMETIME EARLY NEXT WEEK. THE MOISTURE CUT-OFF IS DUE TO THE
WEDNESDAY NIGHT/THURSDAY SYSTEM...WHICH ALLOWS A DRIER HIGH PRESSURE
AREA TO MOVE DOWN TO THE GULF COAST. THEREFORE...THE ENTIRE LONG
TERM FORECAST REMAINS DRY. 850MB TEMPS ARE HINTED TO BE SLIGHTLY
COOLER FOR FRIDAY AND SATURDAY COMPARED TO THE PREVIOUS
FORECAST...DUE TO SOME SEMI-DECENT AGREEMENT ON NORTHERN STREAM
TROUGHING AFFECTING THE FORECAST AREA DURING THIS TIME.
HOWEVER...READINGS ARE STILL LIKELY TO END UP AT OR ABOVE NORMAL FOR
HIGHS AND LOWS WITH A LOT OF THE COLD AIR STAYING WELL NORTH INTO
CANADA. NO REAL STRONG WARM SURGES EITHER DUE TO THE SPLIT FLOW
PATTERN.
&&
.AVIATION...TODAY AND TONIGHT
548 AM CST MON FEB 13 2012
CLOUDS HAVE RAPIDLY INCREASED ACROSS THE AREA THIS MORNING. THESE
CLOUDS ARE IN AVANCE OF A WEAK LOW PRESSURE SYSTEM MOVING OUT OF
THE CENTRAL PLAINS. CEILINGS WILL BE MAINLY VFR THROUGH MID MORNING...
AND THEN BECOME MVFR LATE THIS MORNING AND EARLY AFTERNOON. THIS
SHOULD COINCIDE CLOSELY TO THE DEVELOPMENT OF SNOW. THIS SHOULD
OCCUR AT KRST AROUND 13.17Z AND AT KLSE AROUND 13.19Z. VISIBILITY
REDUCTION DUE TO THE SNOW SHOULD FALL INTO THE 1 TO 2 STATUE MILE
RANGE WITHIN AN HOUR OF SNOW ONSET. ONCE THE SNOW BEGINS IT SHOULD
CONTINUE TO FALL THROUGH THE EVENING...AND THE GRADUALLY END EARLY
TUESDAY MORNING. AS THIS OCCURS...VISIBILITIES SHOULD QUICKLY
CLIMB TO P6SM. SNOW TOTALS AT BOTH TAF SITES SHOULD BE AROUND AN
INCH.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
257 AM CST MON FEB 13 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1114 AM MST MON FEB 13 2012
.UPDATE...
UPDATED TO EXPIRE WINTER WEATHER HIGHLIGHTS FOR THE SOUTHWEST AND
CENTRAL MOUNTAINS. ALSO INCREASED HIGH TEMPERATURES ALONG THE I-25
CORRIDOR AND EASTERN PLAINS TO MATCH CURRENT TRENDS. -PJC
&&
.PREV DISCUSSION... /ISSUED 1051 AM MST MON FEB 13 2012/
AVIATION...
OTHER THAN SOME AREAS OF LOW CLOUDS AND PATCHY FOG IN THE VICINITY
OF KALS THROUGH APPROXIMATELY 20Z/13TH...ANTICIPATE THAT VFR
CONDITIONS SHOULD BE NOTED AT THE KPUB...KCOS AND KALS TAF SITES
FROM THIS AFTERNOON INTO THIS EVENING.
PREV DISCUSSION... /ISSUED 353 AM MST MON FEB 13 2012/
SHORT TERM...
(TODAY AND TONIGHT)
CURRENTLY...SATELLITE IMAGERY INDICATES AN UPPER LEVEL TROUGH
LIFTING NORTHEAST ACROSS EASTERN COLORADO EARLY THIS MORNING. AREA
OBSERVATIONS ARE INDICATING A FEW AREAS OF PATCHY FOG OVER PUEBLO
AND EL PASO COUNTIES. WHERE FOG IS OCCURRING...IT CAN BE DENSE SO
CAUTION IS ADVISED WHEN FOG IS ENCOUNTERED. BESIDES FOG...LIGHT
SNOW CONTINUES ALONG THE CONTINENTAL DIVIDE WITH THE CENTRAL
MOUNTAINS FAVORED IN THE NORTHWEST FLOW. RADAR IS INDICATING LIGHT
SNOW OVER THE EASTERN MOUNTAINS AS WELL. A FEW ECHOES ARE ALSO
SHOWING UP OVER KIOWA COUNTY...BUT THIS IS LIKELY NOT REACHING THE
GROUND AT THIS TIME.
TODAY...THE UPPER LEVEL TROUGH WILL CONTINUE EAST INTO KANSAS
THROUGH THIS AFTERNOON WITH NORTHWESTERLY FLOW REMAINING ENTRENCHED
ACROSS THE REGION. THIS WILL LEAD TO CONTINUED LIGHT SNOW FOR THE
CONTINENTAL DIVIDE...ESPECIALLY OVER THE CENTRAL MOUNTAINS. ANY
ADDITIONAL ACCUMULATIONS TODAY WILL TOTAL 2 TO 4 INCHES WITH THE
HIGHEST AMOUNTS OVER THE CENTRAL MOUNTAINS. THE TROUBLE SPOT FOR
THIS AFTERNOON LOOKS LIKE TELLER COUNTY. THE GFS AND NAM ARE
PRINTING OUT A PERIOD OF LIGHT SNOWFALL OVER TELLER COUNTY THIS
AFTERNOON WHILE THE HIGHER RESOLUTION WRF RUNS AND HRRR KEEP THE
AREA DRY. KEPT LOW POPS OVER TELLER COUNTY FOR LATE THIS AFTERNOON
AND THIS EVENING TO ACCOUNT FOR THE LOW CHANCES THERE. ANY SNOWFALL
WILL BE LIGHT WITH ONLY AN INCH OR TWO POSSIBLE. TEMPERATURES TODAY
WILL BE THE OTHER ISSUE. GUIDANCE CAME IN VERY WARM...HIGHS WELL
INTO THE 50S. GIVEN THE CLOUD COVER AND HIGH RES MODELS PROJECTING
WEAK NORTH TO EASTERLY FLOW FOR THE NORTHERN HALF OF THE
PLAINS...HAVE A FEELING HIGHS WILL BE MUCH COOLER THAN THIS. FOR
NOW HAVE HIGHS GENERALLY IN THE LOWER TO MID 40S FOR THE PLAINS.
THE EXCEPTION WILL LIKELY BE ALONG THE LEE SLOPES OF THE EASTERN
MOUNTAINS WHERE DOWNSLOPE WILL LIKELY ADD A FEW DEGREES TO THE HIGHS.
TONIGHT...HIGH PRESSURE WILL BUILD ACROSS THE REGION AHEAD OF THE
NEXT STORM SYSTEM WHICH IS FORECAST TO DIG ACROSS THE GREAT BASIN.
LIGHT SNOW WILL CONTINUE ALONG THE CONTINENTAL DIVIDE AND LIKELY
INCREASE SOME TOWARDS TUESDAY MORNING AS FLOW TRANSITIONS TO
SOUTHWESTERLY. LOWS WILL BE IN THE LOWER 20S FOR MUCH OF THE
REGION. 88
LONG TERM...
(TUESDAY THROUGH MONDAY)
.TUES/WED WX SYSTEM A BIT WEAKER...
LATEST SIMULATIONS HAVE BACKED OFF A BIT ON THE INTENSITY OF THE WX
SYSTEM THAT WILL TRACK ACROSS THE REGION DURING THE TUE/WED TIME PD.
SIMULATIONS ARE NOW A BIT FARTHER SOUTH AND NOT AS "WRAPPED UP" AS
THEY WERE 24H AGO. WE WILL STILL LIKELY SEE SNOWS ALONG THE
CONTDVD BUT THE PRECIP ON THE PLAINS...ESPECIALLY THE PALMER
DVD...LOOKS TO BE QUITE A BIT LESS. FOR NOW HAVE KEPT HIGH POPS
ALONG THE CONTDVD STARTING TOMORROW AFTERNOON AND LASTING THROUGH
THE NIGHT. IT APPEARS THAT THE HEAVIEST SNOW WILL LIKELY FALL ON
THE SW FACING SLOPES OF THE SAN JUANS WERE UP TO A FOOT WILL BE
POSSIBLE. WINTER WX HILITES WILL LIKELY BE NEEDED FOR THIS REGION
LATER TODAY.
PRECIPITATION WILL LIKELY DEVELOP OVER THE PIKES PEAK REGION LATE
TUESDAY NIGHT AND DECREASE BY WED AFTERNOON. THE HEAVY SNOW WHICH
WAS FCST 24H AGO FOR THIS REGION HAS BACKED OFF CONSIDERABLY...AND
NOW IT LOOKS LIKE AMOUNTS WILL BE IN THE 1 TO 2" AMOUNTS...IF
THAT.
LOOKING AT THE REST OF THE FCST...IT STILL APPEARS MOST AREAS WILL
BE DRY FROM THU INTO EARLY NEXT WEEK. THE EXCEPTION WILL BE ALONG
THE CONTDVD WERE OCCNL SNOW SHOWERS WILL BE POSSIBLE THROUGHOUT
THE PERIOD.
TEMPS THROUGH THE PERIOD WILL STAY ON THE COOL SIDE...WITH MAINLY
40S OVER THE PLAINS AND 20S AND 30S IN THE MTNS. OCCNL MAINLY DRY
COOL FRONTS WILL MOVE ACROSS THE PLAINS IN THE NW FLOW ALOFT.
/34
AVIATION...
KPUB...PATCHY FOG HAVE DEVELOPED THIS MORNING AROUND THE KPUB
TERMINAL AND HAVE LOWERED VIS TO MVFR. FOG SHOULD DIMINISH AND VFR
CONDITIONS WILL PREVAIL BY 13Z THIS MORNING. MODELS HINTING AT FOG
DEVELOPING AGAIN TONIGHT AFTER AROUND 04Z.
KALS...CURRENT OBSERVATIONS INDICATE LOW CLOUDS HAVE DEVELOPED OVER
THE TERMINAL WITH CIGS LOWERING TO 500 FEET. EXPECT THESE LOW CIGS
THROUGH THE NEXT SEVERAL HOURS WITH IMPROVING CONDITIONS BY 16Z.
EXPECT VFR CONDITIONS ONCE THE LOW STRATUS DISSIPATE.
KCOS...EXPECT VFR CONDITIONS THROUGH TONIGHT. 88
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
81/50
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1051 AM MST MON FEB 13 2012
.AVIATION...
OTHER THAN SOME AREAS OF LOW CLOUDS AND PATCHY FOG IN THE VICINITY
OF KALS THROUGH APPROXIMATELY 20Z/13TH...ANTICIPATE THAT VFR
CONDITIONS SHOULD BE NOTED AT THE KPUB...KCOS AND KALS TAF SITES
FROM THIS AFTERNOON INTO THIS EVENING.
&&
.PREV DISCUSSION... /ISSUED 353 AM MST MON FEB 13 2012/
SHORT TERM...
(TODAY AND TONIGHT)
CURRENTLY...SATELLITE IMAGERY INDICATES AN UPPER LEVEL TROUGH
LIFTING NORTHEAST ACROSS EASTERN COLORADO EARLY THIS MORNING. AREA
OBSERVATIONS ARE INDICATING A FEW AREAS OF PATCHY FOG OVER PUEBLO
AND EL PASO COUNTIES. WHERE FOG IS OCCURRING...IT CAN BE DENSE SO
CAUTION IS ADVISED WHEN FOG IS ENCOUNTERED. BESIDES FOG...LIGHT
SNOW CONTINUES ALONG THE CONTINENTAL DIVIDE WITH THE CENTRAL
MOUNTAINS FAVORED IN THE NORTHWEST FLOW. RADAR IS INDICATING LIGHT
SNOW OVER THE EASTERN MOUNTAINS AS WELL. A FEW ECHOES ARE ALSO
SHOWING UP OVER KIOWA COUNTY...BUT THIS IS LIKELY NOT REACHING THE
GROUND AT THIS TIME.
TODAY...THE UPPER LEVEL TROUGH WILL CONTINUE EAST INTO KANSAS
THROUGH THIS AFTERNOON WITH NORTHWESTERLY FLOW REMAINING ENTRENCHED
ACROSS THE REGION. THIS WILL LEAD TO CONTINUED LIGHT SNOW FOR THE
CONTINENTAL DIVIDE...ESPECIALLY OVER THE CENTRAL MOUNTAINS. ANY
ADDITIONAL ACCUMULATIONS TODAY WILL TOTAL 2 TO 4 INCHES WITH THE
HIGHEST AMOUNTS OVER THE CENTRAL MOUNTAINS. THE TROUBLE SPOT FOR
THIS AFTERNOON LOOKS LIKE TELLER COUNTY. THE GFS AND NAM ARE
PRINTING OUT A PERIOD OF LIGHT SNOWFALL OVER TELLER COUNTY THIS
AFTERNOON WHILE THE HIGHER RESOLUTION WRF RUNS AND HRRR KEEP THE
AREA DRY. KEPT LOW POPS OVER TELLER COUNTY FOR LATE THIS AFTERNOON
AND THIS EVENING TO ACCOUNT FOR THE LOW CHANCES THERE. ANY SNOWFALL
WILL BE LIGHT WITH ONLY AN INCH OR TWO POSSIBLE. TEMPERATURES TODAY
WILL BE THE OTHER ISSUE. GUIDANCE CAME IN VERY WARM...HIGHS WELL
INTO THE 50S. GIVEN THE CLOUD COVER AND HIGH RES MODELS PROJECTING
WEAK NORTH TO EASTERLY FLOW FOR THE NORTHERN HALF OF THE
PLAINS...HAVE A FEELING HIGHS WILL BE MUCH COOLER THAN THIS. FOR
NOW HAVE HIGHS GENERALLY IN THE LOWER TO MID 40S FOR THE PLAINS.
THE EXCEPTION WILL LIKELY BE ALONG THE LEE SLOPES OF THE EASTERN
MOUNTAINS WHERE DOWNSLOPE WILL LIKELY ADD A FEW DEGREES TO THE HIGHS.
TONIGHT...HIGH PRESSURE WILL BUILD ACROSS THE REGION AHEAD OF THE
NEXT STORM SYSTEM WHICH IS FORECAST TO DIG ACROSS THE GREAT BASIN.
LIGHT SNOW WILL CONTINUE ALONG THE CONTINENTAL DIVIDE AND LIKELY
INCREASE SOME TOWARDS TUESDAY MORNING AS FLOW TRANSITIONS TO
SOUTHWESTERLY. LOWS WILL BE IN THE LOWER 20S FOR MUCH OF THE
REGION. 88
LONG TERM...
(TUESDAY THROUGH MONDAY)
..TUES/WED WX SYSTEM A BIT WEAKER...
LATEST SIMULATIONS HAVE BACKED OFF A BIT ON THE INTENSITY OF THE WX
SYSTEM THAT WILL TRACK ACROSS THE REGION DURING THE TUE/WED TIME PD.
SIMULATIONS ARE NOW A BIT FARTHER SOUTH AND NOT AS "WRAPPED UP" AS
THEY WERE 24H AGO. WE WILL STILL LIKELY SEE SNOWS ALONG THE
CONTDVD BUT THE PRECIP ON THE PLAINS...ESPECIALLY THE PALMER
DVD...LOOKS TO BE QUITE A BIT LESS. FOR NOW HAVE KEPT HIGH POPS
ALONG THE CONTDVD STARTING TOMORROW AFTERNOON AND LASTING THROUGH
THE NIGHT. IT APPEARS THAT THE HEAVIEST SNOW WILL LIKELY FALL ON
THE SW FACING SLOPES OF THE SAN JUANS WERE UP TO A FOOT WILL BE
POSSIBLE. WINTER WX HILITES WILL LIKELY BE NEEDED FOR THIS REGION
LATER TODAY.
PRECIPITATION WILL LIKELY DEVELOP OVER THE PIKES PEAK REGION LATE
TUESDAY NIGHT AND DECREASE BY WED AFTERNOON. THE HEAVY SNOW WHICH
WAS FCST 24H AGO FOR THIS REGION HAS BACKED OFF CONSIDERABLY...AND
NOW IT LOOKS LIKE AMOUNTS WILL BE IN THE 1 TO 2" AMOUNTS...IF
THAT.
LOOKING AT THE REST OF THE FCST...IT STILL APPEARS MOST AREAS WILL
BE DRY FROM THU INTO EARLY NEXT WEEK. THE EXCEPTION WILL BE ALONG
THE CONTDVD WERE OCCNL SNOW SHOWERS WILL BE POSSIBLE THROUGHOUT
THE PERIOD.
TEMPS THROUGH THE PERIOD WILL STAY ON THE COOL SIDE...WITH MAINLY
40S OVER THE PLAINS AND 20S AND 30S IN THE MTNS. OCCNL MAINLY DRY
COOL FRONTS WILL MOVE ACROSS THE PLAINS IN THE NW FLOW ALOFT.
/34
AVIATION...
KPUB...PATCHY FOG HAVE DEVELOPED THIS MORNING AROUND THE KPUB
TERMINAL AND HAVE LOWERED VIS TO MVFR. FOG SHOULD DIMINISH AND VFR
CONDITIONS WILL PREVAIL BY 13Z THIS MORNING. MODELS HINTING AT FOG
DEVELOPING AGAIN TONIGHT AFTER AROUND 04Z.
KALS...CURRENT OBSERVATIONS INDICATE LOW CLOUDS HAVE DEVELOPED OVER
THE TERMINAL WITH CIGS LOWERING TO 500 FEET. EXPECT THESE LOW CIGS
THROUGH THE NEXT SEVERAL HOURS WITH IMPROVING CONDITIONS BY 16Z.
EXPECT VFR CONDITIONS ONCE THE LOW STRATUS DISSIPATE.
KCOS...EXPECT VFR CONDITIONS THROUGH TONIGHT. 88
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1257 PM CST MON FEB 13 2012
.UPDATE...
TEMPERATURES CONTINUE TO CLIMB IN THE EASTERN CWFA AND ELSEWHERE
WHERE THE SNOW IS EXTREMELY LIGHT.
RUC TRENDS SHOW THE STRONGEST LIFT/FORCING IS GENERALLY ABOVE OR
BELOW THE FAVORED DENDRITIC ZONE. THIS EXPLAINS THE VERY SMALL
NATURE OF THE SNOWFLAKES THAT HAVE BEEN OBSERVED OR REPORTED. SUCH
SMALL FLAKES COMBINED WITH THE WARM TEMPERATURES WILL LIKELY
RESULT IN SOMEWHAT LOWER SNOW AMOUNTS. SO FAR MOST SNOWFALL
REPORTS HAVE BEEN BETWEEN A TRACE AND ONE HALF INCH.
WATER VAPOR AND RUC TRENDS CONTINUE TO SHOW THE WAA WIND OF
VORTICITY ROTATING OUT OF THE CWFA BY MID AFTERNOON WHICH MAY
RESULT IN A LULL IN OVERALL SNOWFALL. HOWEVER...THE RUC ALSO HAS
AN EVEN WEAKER WAVE WITH VORT MAXES THAT ROTATES THROUGH DURING
THE SECOND HALF OF THE AFTERNOON AND EARLY EVENING. WATER VAPOR
SUGGESTS THIS BUT IT IS VERY SUBTLE IN NATURE.
BASED ON THIS A MAJORITY OF THE SNOWFALL FROM THIS SYSTEM WILL
HAVE ALREADY OCCURRED BY THE EVENING COMMUTE.
..08..
&&
.PREV DISCUSSION... /ISSUED 1130 AM CST MON FEB 13 2012/
AVIATION...
CONDITIONS RANGE FROM VFR TO MVFR BASED ON THE BANDED NATURE OF
THE PRECIPITATION. LOCALIZED BRIEF IFR CONDITIONS ARE ALSO
OCCURRING IN THE HEAVIER SNOW BANDS. CONDITIONS ARE EXPECTED TO
DETERIORATE TO MVFR AND IFR CONDITIONS THROUGH 00Z/14 BUT BRIEF
PERIODS OF VFR ARE POSSIBLE. FORECAST SOUNDINGS STILL INDICATE THE
POTENTIAL FOR FZDZ AND SEVERAL SITES IN WESTERN IOWA ARE REPORTING
UP FOR PRESENT WX. BASED ON THIS THE START TIME FOR FZDZ HAS BEEN
MOVED FORWARD WITH THE 18Z TAFS.
.08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1130 AM CST MON FEB 13 2012
.AVIATION...
CONDITIONS RANGE FROM VFR TO MVFR BASED ON THE BANDED NATURE OF
THE PRECIPITATION. LOCALIZED BRIEF IFR CONDITIONS ARE ALSO
OCCURRING IN THE HEAVIER SNOW BANDS. CONDITIONS ARE EXPECTED TO
DETERIORATE TO MVFR AND IFR CONDITIONS THROUGH 00Z/14 BUT BRIEF
PERIODS OF VFR ARE POSSIBLE. FORECAST SOUNDINGS STILL INDICATE THE
POTENTIAL FOR FZDZ AND SEVERAL SITES IN WESTERN IOWA ARE REPORTING
UP FOR PRESENT WX. BASED ON THIS THE START TIME FOR FZDZ HAS BEEN
MOVED FORWARD WITH THE 18Z TAFS.
..08..
&&
.PREV DISCUSSION... /ISSUED 1047 AM CST MON FEB 13 2012/
UPDATE...
THE FCST HAS BEEN UPDATED TO REFLECT CURRENT TRENDS.
THE INITIAL BURST OF SNOW ACROSS THE AREA IS ASSOCIATED WITH A
WING OF VORTICITY WITH A WEAK WAVE. RUC TRENDS HAVE THIS VORT
LOBE ROTATING INTO SOUTHERN WISCONSIN EARLY THIS AFTERNOON. BASED
ON OBSERVATIONS AND SNOW AMOUNTS UPSTREAM...THIS VORT LOBE WILL
LIKELY ACCOUNT FOR ONE THIRD TO 40 PERCENT OF THE TOTAL SNOWFALL
FOR THIS STORM SYSTEM.
RUC TRENDS BRING IN SOME ADDITIONAL VORT MAXES ASSOCIATED WITH
ANOTHER ALBEIT WEAKER WAVE ALOFT THAT SHOULD ALLOW LIGHT SNOW TO
PERSIST THROUGH THE AFTERNOON AND GIVE SOME ADDITIONAL LIGHT
ACCUMULATIONS.
OVERALL SNOW ACCUMULATIONS THROUGH SUNSET SHOULD RANGE FROM ABOUT
ONE HALF OF AN INCH TO JUST OVER AN INCH.
TONIGHT THE MAIN WAVE IS PROGGED TO ROTATE THROUGH THE AREA
BRINGING SOME ADDITIONAL SNOW. HOWEVER...FCST SOUNDINGS SHOW
DRYING OUT OCCURRING ALOFT SO THE POTENTIAL FOR FZDZ APPEARS
VALID. TIMING THE DRYING ALOFT TONIGHT WILL BE THE KEY TO WHEN THE
FZDZ BEGINS.
.08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1047 AM CST MON FEB 13 2012
.UPDATE...
THE FCST HAS BEEN UPDATED TO REFLECT CURRENT TRENDS.
THE INITIAL BURST OF SNOW ACROSS THE AREA IS ASSOCIATED WITH A
WING OF VORTICITY WITH A WEAK WAVE. RUC TRENDS HAVE THIS VORT
LOBE ROTATING INTO SOUTHERN WISCONSIN EARLY THIS AFTERNOON. BASED
ON OBSERVATIONS AND SNOW AMOUNTS UPSTREAM...THIS VORT LOBE WILL
LIKELY ACCOUNT FOR ONE THIRD TO 40 PERCENT OF THE TOTAL SNOWFALL
FOR THIS STORM SYSTEM.
RUC TRENDS BRING IN SOME ADDITIONAL VORT MAXES ASSOCIATED WITH
ANOTHER ALBEIT WEAKER WAVE ALOFT THAT SHOULD ALLOW LIGHT SNOW TO
PERSIST THROUGH THE AFTERNOON AND GIVE SOME ADDITIONAL LIGHT
ACCUMULATIONS.
OVERALL SNOW ACCUMULATIONS THROUGH SUNSET SHOULD RANGE FROM ABOUT
ONE HALF OF AN INCH TO JUST OVER AN INCH.
TONIGHT THE MAIN WAVE IS PROGGED TO ROTATE THROUGH THE AREA
BRINGING SOME ADDITIONAL SNOW. HOWEVER...FCST SOUNDINGS SHOW
DRYING OUT OCCURRING ALOFT SO THE POTENTIAL FOR FZDZ APPEARS
VALID. TIMING THE DRYING ALOFT TONIGHT WILL BE THE KEY TO WHEN THE
FZDZ BEGINS.
..08..
&&
.AVIATION...
CONDITIONS RANGE FROM VFR TO IFR IN BANDS OF -SN WITH THE WINTER
STORM. RADAR SHOWS ANOTHER BAND MOVING NORTHEAST FROM MISSOURI
AND SOUTHERN IOWA WHICH SHOULD GIVE ANOTHER BURST OF -SN AND IFR
CONDITIONS THROUGH 00Z. AFT 00Z/14 FORECAST SOUNDINGS SHOW DRYING
OUT ALOFT DVLPG WHICH SHOULD ALLOW -FZDZ TO DVLP.
..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1152 AM EST MON FEB 13 2012
.SYNOPSIS...
HIGH PRESSURE WILL PROVIDE DRY WEATHER AND SLOWLY MODERATING
TEMPERATURES TODAY. LOW PRESSURE, COMING EAST FROM KANSAS, WILL
BRING A MIX OF SNOW AND RAIN SHOWERS TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
PER RECENT SATELLITE AND SURFACE DATA, EXPECT NO MORE THAN A FEW
CUMULUS AND CIRRUS CLOUDS PASSING ACROSS THE UPPER OHIO VALLEY
THIS AFTERNOON. HENCE IT WILL STAY SUNNY.
H8 TEMPERATURES HAVE BEEN WARMING, SO SURFACE TEMPERATURES WILL
CONTINUE MODERATING THIS AFTERNOON, ALTHOUGH SNOW PACK REFLECTION
AND SUBLIMATION WILL SERVE AS RESTRICTIONS. RECENT HRRR AND GFS
LAMP MODEL OUTPUT SUPPORT PREVIOUS NAM AND GFS MOS VALUES IN
FORECASTING HIGHS, EXPECT HIGHS IN THE LOWER TO MID 30S, WHICH IS
5 TO 8 DEGREES COLDER THAN NORMAL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
RECENT SREF AND NAM MODEL OUTPUT CONTINUE TO SHOW A LOW PRESSURE
SYSTEM COMING EAST FROM KANSAS PASSING THROUGH THE UPPER OHIO
VALLEY TUESDAY.
BASED ON RECENT NAM MODEL PROFILES, THE INITIAL PRECIPITATION
TYPE WILL BE SNOW TUESDAY MORNING. PREFRONTAL SOUTHERLY WINDS MAY
PUSH ENOUGH SURFACE LAYER WARMTH TO PROMOTE A CHANGE TO RAIN
SHOWERS AS FAR NORTH AS THE I-70 CORRIDOR AND PITTSBURGH TUESDAY
AFTERNOON. DUE TO A ZONAL JETSTREAM ALOFT, POST FRONTAL COOLING
WILL BE WEAK, SO CORRESPONDING POST FRONTAL SNOW SHOWERS WILL
LIKEWISE BE WEAK AND SHORT-LIVED.
THE ENTIRE SYSTEM PASSAGE WILL PRODUCE LIGHT PRECIPITATION AMOUNTS.
SO ANY SNOW AMOUNTS TUESDAY INTO TUESDAY NIGHT SHOULD BE LIMITED
TO NO MORE THAN 2 INCHES NORTH AND MOUNTAINS, AND 1 INCH SOUTH.
HIGH PRESSURE WILL BRING DRY CONDITIONS WEDNESDAY.
FORECASTED HIGH TEMPERATURES, BASED ON RECENT GFS AND NAM MOS VALUES, TO
BE NEAR NORMAL BOTH TUESDAY AND WEDNESDAY, WHILE CLOUDY SKIES WILL
PROMOTE WARMER THAN NORMAL NIGHTTIME LOWS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
MEDIUM RANGE MODELS SHOW A BROAD UPPER TROUGH MOVING ACROSS THE
NORTHERN MS VALLEY TO THE GREAT LAKES REGION BY FRIDAY. ASSOCIATED
SURFACE LOW IS PROGGED TO TRACK FROM THE PLAINS NORTHEASTWARD ACROSS
THE GREAT LAKES. MIXED RAIN AND SNOW SHOWERS SHOULD CHANGE TO MAINLY
ALL RAIN BY THURSDAY AFTERNOON AS TEMPERATURES WARM....THEN BACK TO
SCATTERED SNOW SHOWERS THURSDAY NIGHT.
THE SYSTEM WILL MOVE EAST OF THE REGION FRIDAY...BUT LINGERING
MOISTURE AND NORTHWEST FLOW SHOULD MAINTAIN A FEW SHOWERS OVER THE
FORECAST AREA ESPECIALLY NORTH OF I-80. A WEAK SYSTEM PASSING TO OUR
NORTH COUPLED WITH NORTHWEST FLOW WILL KEEP CLOUDINESS AND ISOLATED
SHOWERS OVER THE REGION DURING THE WEEKEND.
TEMPERATURES ARE FORECAST TO BE A FEW DEGREES ABOVE NORMAL DURING
THE EXTENDED PERIOD.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
PER RECENT SURFACE AND SATELLITE DATA, EXPECT VFR WITH FEW
CUMULUS THIS AFTERNOON. CIRRUS CLOUDS WILL BE ON THE INCREASE
EARLY TONIGHT, FOLLOWED BY ALTOCUMULUS CLOUDS LATE TONIGHT, FROM
THE LOW PRESSURE SYSTEM COMING EASTBOUND FROM KANSAS.
WINDS WILL BE 5-10KTS OUT OF THE SOUTHWEST.
OUTLOOK...TUESDAY THROUGH FRIDAY...
MIX OF SNOW AND RAIN SHOWERS WITH MAINLY MVFR RESTRICTIONS TUESDAY
INTO TUESDAY NIGHT WITH LOW PRESSURE SYSTEM PASSAGE. ENSUING HIGH
PRESSURE WILL BRING VFR WEDNESDAY. RESTRICTIONS POSSIBLE THURSDAY
INTO FRIDAY, DUE TO A MIX OF RAIN AND SNOW SHOWERS ASSOCIATED WITH
THE PASSAGE OF A STRONGER LOW PRESSURE SYSTEM, COMING NORTHEAST FROM
THE PLAINS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
546 PM EST MON FEB 13 2012
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 400 PM EST MON FEB 13 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL SHORTWAVE
TROUGH MOVING FROM THE CNTRL PLAINS TOWARD THE MID MS VALLEY AND
CONFLUENT FLOW FROM NRN ONTARIO INTO THE NRN LAKES ON THE PERIPHERY OF
THE DEEP TROUGH OVER ERN CANADA. LIGHT SNOW ASSOCIATED WITH THE
SHRTWV HAD ADVANCED INTO SRN WI. AT THE SFC...SRLY FLOW PREVAILED
FROM MO/IA INTO WI UPPER MI AHEAD OF A TROUGH OVER THE PLAINS.
VIS LOOP SHOWED MID CLOUDS HAD SPREAD FROM NRN WI THROUGH THE SW
HALF OF UPPER MI WITH LOW/MID LEVEL MOISTURE ADVECTION AHEAD OF THE
LOW.
TONIGHT INTO TUESDAY...EXPECT CLOUDS TO SPREAD ACROSS THE REST OF
THE CWA LATE THIS AFTERNOON AND PERSIST THROUGH TUESDAY...PER
SATELLITE TRENDS AND NAM/GFS SFC-850 RH FCST. ALTHOUGH THE PCPN OVER
SRN WI CONTINUED TO SPREAD TO THE NORTH...WITH ONLY VERY WEAK FORCING
QVECTOR CONV...FGEN OR ISENTROPIC LIFT...ANY LIGHT SNOW MOVING INTO
THE AREA SHOULD BE VERY LIGHT AND BE CONFINED TO THE FAR SOUTH CWA
(SOUTH OF US-2)...PER GFS/ECMWF AND REGIONAL GEM. CLOUDS WILL HOLD
TEMPS UP TONIGHT WITH MIN READINGS MAINLY IN THE 20S. WITH THE
RELATIVELY MILD AIRMASS LINGERING OVER THE AREA TUESDAY...MAX
READINGS SHOULD STILL CLIMB INTO THE LOWER TO MID 30S...DESPITE THE
LINGERING CLOUDS.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 400 PM EST MON FEB 13 2012
WED THRU MON...UNDER SPLIT FLOW REGIME...ARCTIC AIR WILL BE BOTTLED
UP WELL TO THE N INTO NEXT WEEKEND...RESULTING IN TEMPS CONTINUING
TO AVERAGE ABOVE NORMAL. MODELS HINT AT A WEAK SHORTWAVE TO PASS
OVER THE UPPER GREAT LAKES WEDNESDAY. HOWEVER...MID AND UPPER LEVEL
DRY AIR ALONG WITH VERY LITTLE LIFT WILL KEEP MUCH OF UPPER MI
PREDOMINATELY DRY DURING THIS TIME FRAME.
CENTRALIZED SHORTWAVE TRAVERSING CALIFORNIA DURING THE DAY TODAY
WILL SLOWLY MOVE E TO THE CENTRAL PLAINS THROUGH WEDNESDAY...THEN
SHIFT TO A MORE NW DIRECTION...REACHING LAKE MI BY 12Z THURSDAY.
SOME MEDIUM RANGE MODELS ARE ALSO POINTING AT THE POTENTIAL FOR NRN
STREAM ENERGY TO PHASE WITH AND POSSIBLY STRENGTHEN THIS SRN STREAM
SYSTEM AS IT NEARS THE GREAT LAKES REGION. MODEL CONSENSUS KEEPS
MOST OF THE PRECIP CENTERED ALONG EASTERN EDGE OF THE PRESSURE
SYSTEM WHERE THE DEEPEST QVECTOR CONV/LIFT WILL BE LOCATED...AS WELL
AS ALONG THE ADJOINING COLD FRONT TO THE SOUTH. SOME OF THIS DEEP
MOISTURE AND QVECTOR CONV COULD REACH SC AND E UPPER MI DURING THE
DAY THURSDAY...ESPECIALLY AS SYSTEM BECOMES MORE WRAPPED UP. MODELS
HINT AT A TROWEL DEVELOPING...PULLING THE COLD FRONT ACROSS SOUTHERN
MENOMINEE COUNTY AND CENTRAL WI ALONG WITH 0.25 TO 0.5 INCH QPF
VALUES. THIS HAS BEEN CONSISTENT IN THE PREVIOUS TWO RUNS OF THE
GFS/ECMWF/AND NAM...THOUGH LATEST 13/12Z GFS AND GEM SEEMED TO PUSH
PRECIP FARTHER SOUTH. AS A RESULT...HAVE CONTINUED WITH EARLIER
CONSENSUS RUNS AND INCREASED POPS AND QPF ACROSS THE CWA. LATEST
MODEL RUNS ALSO SHOW COLDER 850 TEMPERATURE TRENDS...WHILE SURFACE
TEMPS WILL REMAIN RIGHT AT FREEZING...SO EXPECT SNOW TO BE THE MAIN
PRECIP TYPE. WILL CONTINUE TO MONITOR LATEST MODEL RUNS FOR ANY
CHANGE IN PLACEMENTS/WIND DIRECTIONS AND RESULTING PRECIP
TYPES/LOCATIONS.
MIDLEVEL DRY AIR AHEAD OF APPROACHING RIDGE WILL THEN CUT IN BY
THURSDAY NIGHT AS SHORTWAVE MOVES OFF TO THE NORTHEAST...REDUCING
PRECIP CHANCES FROM WEST TO EAST OVERNIGHT. THE RESULT OF THIS UPPER
LEVEL RIDGING WILL BE TO TURN WINDS MORE NORTHWESTERLY BY FRIDAY
INTO SATURDAY...ALLOWING ARCTIC AIR TO PENETRATE SOUTHWARD ACROSS
THE GREAT LAKES. 13/12Z GFS HAS H850 TEMPS DROPPING TO -17C
SATURDAY. THIS...ALONG WITH LINGERING LOW LEVEL MOISTURE...WILL
CREATE THE CONVERGENCE NEEDED FOR LAKE EFFECT SNOW FRIDAY THROUGH
SATURDAY IN AREAS ALONG LAKE SUPERIOR FAVORED BY NW WINDS. 13/12Z
ECMWF ALSO KEEPS WITH THIS TREND...THOUGH FALLING TEMPERATURES AND
AMOUNT OF CONVERGENCE ARE SLIGHTLY LESS MAGNIFIED. AS A
RESULT...HAVE INCREASED SLIGHT CHANCE TO CHANCE POPS ALONG LAKE
SUPERIOR IN AREAS FAVORED BY A NW WIND DIRECTION...KEEPING WITH
PREVIOUS FORECASTS.
ANY LINGERING LES EAST WILL COME TO AN END LATE SATURDAY...AS WINDS
BECOME MORE SOUTHWESTERLY...AHEAD OF THE NEXT SFC LOW/500MB TROUGH
APPROACHING FROM CENTRAL CANADA AND MN. THERE ARE SIGNIFICANT ENOUGH
TIMING DIFFERENCE TO RESULT IN MODERATE CONFIDENCE IN THE FCST
BEYOND THIS PERIOD. WHILE THE GFS AND ECMWF ARE IN FAIRLY GOOD SHAPE
UP UNTIL THIS POINT...THE 13/06Z RUN OF THE GFS BECOMES ROUGHLY 12
HRS SLOWER THAN THE MORE CONSISTENT ECMWF WITH THE HANDLING OF THIS
WAVE /CENTERED ACROSS THE UPPER GREAT LAKES AT 00Z MONDAY...WHILE
THE ECMWF HAS IT OVER THE LOWER GREAT LAKES/. WHILE THE ECMWF
INDICATES A DRY FRONTAL PASSAGE WITH THE SFC LOW CENTERED OVER
NORTHERN ONTARIO. GIVEN THE SLOWER AND MORE SOUTHERN GFS...A BROAD
SFC LOW WILL LIKELY DEVELOP OVER THE GREAT LAKES...WITH LIGHT PRECIP
AND PLENTY OF CLOUD COVER BEFORE THE SYSTEM EJECTS EASTWARD MONDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 546 PM EST MON FEB 13 2012
A DISTURBANCE MOVING FROM THE CNTRL PLAINS TO THE LOWER GREAT LKS
WILL HAVE THE LOWER TO MID CLOUDS TO LOWER THROUGH THE NIGHT AND
LIKELY BE IN THE MVFR CAT AFTER 06Z.
MODELS WERE HINTING AT PLENTY OF LLVL MOISTENING...WHICH COULD LEAD
TO SOME REDUCED VSBYS FROM BR. WITH LIMITED LLVL LIFT AND SINCE
WINDS WILL BE OUT OF AN UNFAVORABLE SWRLY DIRECTION...WILL KEEP VSBY
REDUCTION OUT AT THIS TIME.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 400 PM EST MON FEB 13 2012
A HIGH PRESSURE RIDGE BUILDING OVER THE AREA WILL KEEP WINDS BELOW
20KTS TONIGHT THROUGH WEDNESDAY. A LOW PRESSURE SYSTEM
DEVELOPING OVER THE CENTRAL PLAINS ON WED NIGHT WILL MOVE THROUGH
THE GREAT LAKES REGION FROM THURSDAY INTO FRIDAY. THIS WILL
LEAD TO NW WINDS UP TO 25KTS OVER ERN LK SUPERIOR. HIGH PRESSURE
WILL THEN MOVE OVER THE AREA FOR THE FIRST PART OF THE WEEKEND AND
KEEP WINDS BELOW 20KTS. WITH ABOVE NORMAL TEMPERATURES THROUGH THE
PERIOD...LITTLE TO NO FREEZING SPRAY IS EXPECTED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JMW
AVIATION...07
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
400 PM EST MON FEB 13 2012
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 400 PM EST MON FEB 13 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL SHORTWAVE
TROUGH MOVING FROM THE CNTRL PLAINS TOWARD THE MID MS VALLEY AND
CONFLUENT FLOW FROM NRN ONTARIO INTO THE NRN LAKES ON THE PERIPHERY OF
THE DEEP TROUGH OVER ERN CANADA. LIGHT SNOW ASSOCIATED WITH THE
SHRTWV HAD ADVANCED INTO SRN WI. AT THE SFC...SRLY FLOW PREVAILED
FROM MO/IA INTO WI UPPER MI AHEAD OF A TROUGH OVER THE PLAINS.
VIS LOOP SHOWED MID CLOUDS HAD SPREAD FROM NRN WI THROUGH THE SW
HALF OF UPPER MI WITH LOW/MID LEVEL MOISTURE ADVECTION AHEAD OF THE
LOW.
TONIGHT INTO TUESDAY...EXPECT CLOUDS TO SPREAD ACROSS THE REST OF
THE CWA LATE THIS AFTERNOON AND PERSIST THROUGH TUESDAY...PER
SATELLITE TRENDS AND NAM/GFS SFC-850 RH FCST. ALTHOUGH THE PCPN OVER
SRN WI CONTINUED TO SPREAD TO THE NORTH...WITH ONLY VERY WEAK FORCING
QVECTOR CONV...FGEN OR ISENTROPIC LIFT...ANY LIGHT SNOW MOVING INTO
THE AREA SHOULD BE VERY LIGHT AND BE CONFINED TO THE FAR SOUTH CWA
(SOUTH OF US-2)...PER GFS/ECMWF AND REGIONAL GEM. CLOUDS WILL HOLD
TEMPS UP TONIGHT WITH MIN READINGS MAINLY IN THE 20S. WITH THE
RELATIVELY MILD AIRMASS LINGERING OVER THE AREA TUESDAY...MAX
READINGS SHOULD STILL CLIMB INTO THE LOWER TO MID 30S...DESPITE THE
LINGERING CLOUDS.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 400 PM EST MON FEB 13 2012
WED THRU MON...UNDER SPLIT FLOW REGIME...ARCTIC AIR WILL BE BOTTLED
UP WELL TO THE N INTO NEXT WEEKEND...RESULTING IN TEMPS CONTINUING
TO AVERAGE ABOVE NORMAL. MODELS HINT AT A WEAK SHORTWAVE TO PASS
OVER THE UPPER GREAT LAKES WEDNESDAY. HOWEVER...MID AND UPPER LEVEL
DRY AIR ALONG WITH VERY LITTLE LIFT WILL KEEP MUCH OF UPPER MI
PREDOMINATELY DRY DURING THIS TIME FRAME.
CENTRALIZED SHORTWAVE TRAVERSING CALIFORNIA DURING THE DAY TODAY
WILL SLOWLY MOVE E TO THE CENTRAL PLAINS THROUGH WEDNESDAY...THEN
SHIFT TO A MORE NW DIRECTION...REACHING LAKE MI BY 12Z THURSDAY.
SOME MEDIUM RANGE MODELS ARE ALSO POINTING AT THE POTENTIAL FOR NRN
STREAM ENERGY TO PHASE WITH AND POSSIBLY STRENGTHEN THIS SRN STREAM
SYSTEM AS IT NEARS THE GREAT LAKES REGION. MODEL CONSENSUS KEEPS
MOST OF THE PRECIP CENTERED ALONG EASTERN EDGE OF THE PRESSURE
SYSTEM WHERE THE DEEPEST QVECTOR CONV/LIFT WILL BE LOCATED...AS WELL
AS ALONG THE ADJOINING COLD FRONT TO THE SOUTH. SOME OF THIS DEEP
MOISTURE AND QVECTOR CONV COULD REACH SC AND E UPPER MI DURING THE
DAY THURSDAY...ESPECIALLY AS SYSTEM BECOMES MORE WRAPPED UP. MODELS
HINT AT A TROWEL DEVELOPING...PULLING THE COLD FRONT ACROSS SOUTHERN
MENOMINEE COUNTY AND CENTRAL WI ALONG WITH 0.25 TO 0.5 INCH QPF
VALUES. THIS HAS BEEN CONSISTENT IN THE PREVIOUS TWO RUNS OF THE
GFS/ECMWF/AND NAM...THOUGH LATEST 13/12Z GFS AND GEM SEEMED TO PUSH
PRECIP FARTHER SOUTH. AS A RESULT...HAVE CONTINUED WITH EARLIER
CONSENSUS RUNS AND INCREASED POPS AND QPF ACROSS THE CWA. LATEST
MODEL RUNS ALSO SHOW COLDER 850 TEMPERATURE TRENDS...WHILE SURFACE
TEMPS WILL REMAIN RIGHT AT FREEZING...SO EXPECT SNOW TO BE THE MAIN
PRECIP TYPE. WILL CONTINUE TO MONITOR LATEST MODEL RUNS FOR ANY
CHANGE IN PLACEMENTS/WIND DIRECTIONS AND RESULTING PRECIP
TYPES/LOCATIONS.
MIDLEVEL DRY AIR AHEAD OF APPROACHING RIDGE WILL THEN CUT IN BY
THURSDAY NIGHT AS SHORTWAVE MOVES OFF TO THE NORTHEAST...REDUCING
PRECIP CHANCES FROM WEST TO EAST OVERNIGHT. THE RESULT OF THIS UPPER
LEVEL RIDGING WILL BE TO TURN WINDS MORE NORTHWESTERLY BY FRIDAY
INTO SATURDAY...ALLOWING ARCTIC AIR TO PENETRATE SOUTHWARD ACROSS
THE GREAT LAKES. 13/12Z GFS HAS H850 TEMPS DROPPING TO -17C
SATURDAY. THIS...ALONG WITH LINGERING LOW LEVEL MOISTURE...WILL
CREATE THE CONVERGENCE NEEDED FOR LAKE EFFECT SNOW FRIDAY THROUGH
SATURDAY IN AREAS ALONG LAKE SUPERIOR FAVORED BY NW WINDS. 13/12Z
ECMWF ALSO KEEPS WITH THIS TREND...THOUGH FALLING TEMPERATURES AND
AMOUNT OF CONVERGENCE ARE SLIGHTLY LESS MAGNIFIED. AS A
RESULT...HAVE INCREASED SLIGHT CHANCE TO CHANCE POPS ALONG LAKE
SUPERIOR IN AREAS FAVORED BY A NW WIND DIRECTION...KEEPING WITH
PREVIOUS FORECASTS.
ANY LINGERING LES EAST WILL COME TO AN END LATE SATURDAY...AS WINDS
BECOME MORE SOUTHWESTERLY...AHEAD OF THE NEXT SFC LOW/500MB TROUGH
APPROACHING FROM CENTRAL CANADA AND MN. THERE ARE SIGNIFICANT ENOUGH
TIMING DIFFERENCE TO RESULT IN MODERATE CONFIDENCE IN THE FCST
BEYOND THIS PERIOD. WHILE THE GFS AND ECMWF ARE IN FAIRLY GOOD SHAPE
UP UNTIL THIS POINT...THE 13/06Z RUN OF THE GFS BECOMES ROUGHLY 12
HRS SLOWER THAN THE MORE CONSISTENT ECMWF WITH THE HANDLING OF THIS
WAVE /CENTERED ACROSS THE UPPER GREAT LAKES AT 00Z MONDAY...WHILE
THE ECMWF HAS IT OVER THE LOWER GREAT LAKES/. WHILE THE ECMWF
INDICATES A DRY FRONTAL PASSAGE WITH THE SFC LOW CENTERED OVER
NORTHERN ONTARIO. GIVEN THE SLOWER AND MORE SOUTHERN GFS...A BROAD
SFC LOW WILL LIKELY DEVELOP OVER THE GREAT LAKES...WITH LIGHT PRECIP
AND PLENTY OF CLOUD COVER BEFORE THE SYSTEM EJECTS EASTWARD MONDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1225 PM EST MON FEB 13 2012
A DISTURBANCE MOVING FROM THE CNTRL PLAINS TO THE LOWER GREAT LKS
WILL BRING INCREASING MID CLOUDS LATE THIS AFTN INTO
TONIGHT. EXPECT THE CLOUDS TO LOWER THROUGH THE NIGHT AND LIKELY BE
IN THE MVFR CAT AFTER 06Z.
MODELS WERE HINTING AT PLENTY OF LLVL MOISTENING...WHICH COULD LEAD
TO SOME REDUCED VSBYS FROM BR. WITH LIMITED LLVL LIFT AND SINCE
WINDS WILL BE OUT OF AN UNFAVORABLE SWRLY DIRECTION...WILL KEEP VSBY
REDUCTION OUT AT THIS TIME.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 400 PM EST MON FEB 13 2012
A HIGH PRESSURE RIDGE BUILDING OVER THE AREA WILL KEEP WINDS BELOW
20KTS TONIGHT THROUGH WEDNESDAY. A LOW PRESSURE SYSTEM
DEVELOPING OVER THE CENTRAL PLAINS ON WED NIGHT WILL MOVE THROUGH
THE GREAT LAKES REGION FROM THURSDAY INTO FRIDAY. THIS WILL
LEAD TO NW WINDS UP TO 25KTS OVER ERN LK SUPERIOR. HIGH PRESSURE
WILL THEN MOVE OVER THE AREA FOR THE FIRST PART OF THE WEEKEND AND
KEEP WINDS BELOW 20KTS. WITH ABOVE NORMAL TEMPERATURES THROUGH THE
PERIOD...LITTLE TO NO FREEZING SPRAY IS EXPECTED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JMW
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS BILLINGS MT
958 AM MST MON FEB 13 2012
.SHORT TERM...VALID FOR TDY AND TUE...
ONLY MINOR CHANGES ARE BEING MADE TO TODAY/S FORECAST. WE HAVE HAD
A BIT OF SHOWER ACTIVITY THIS MORNING IN RESPONSE TO CYCLONIC FLOW
ASSOCIATED WITH A SHORT WAVE CENTERED NEAR WILLISTON ND AT 16 UTC.
WE HAVE DECIDED TO CARRY A SLIGHT CHANCE FOR RAIN AND SNOW SHOWERS
ACROSS MUCH OF THE PLAINS THIS AFTERNOON SINCE THIS SITUATION WILL
CONTINUE FOR AT LEAST A FEW MORE HOURS. TEMPERATURES AT THIS POINT
ARE ACTUALLY RUNNING A BIT AHEAD OF THE FORECAST CURVE IN RESPONSE
TO THE CLOUD COVER THAT INHIBITED SUBSTANTIAL SURFACE COOLING THIS
MORNING. HOWEVER...THOSE SAME CLOUDS LOOK TO HOLD TIGHT OVER A LOT
OF THE AREA THIS AFTERNOON BASED ON SATELLITE IMAGERY...SO WE WILL
NOT INCREASE HIGH TEMPERATURES MUCH AT THIS POINT. MIXING TO ABOUT
850 HPA YIELDS HIGHS CLOSE TO THE CURRENT FORECAST...THOUGH WE DID
NOTE THAT THE LATEST RUC MIXES SOME PLACES ON THE PLAINS DEEPER TO
NEAR 800 HPA TODAY...WHICH WOULD RESULT IN HIGHS ABOUT 5 F GREATER
THAN WHAT WE CURRENTLY HAVE ADVERTISED. SCHULTZ
.LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN...
BETTER MODEL AGREEMENT FOR THE EXTENDED PERIOD AS MODELS ARE
CONSISTENT WITH KEEPING MONTANA AND WYOMING UNDER NORTHERN BRANCH
OF ENERGY FOR WEDNESDAY WITH THE SPLIT FLOW STAYING SOUTH OF THE
AREA. THIS BRINGS A SERIES A DISTURBANCES BEHIND TUESDAY MAIN WAVE
FOR A CHANCE OF LINGERING SHOWER ACTIVITY ESPECIALLY FOR THE
SOUTHEAST CORNER OF THE FORECAST AREA. DID RAISE WINDS A BIT
WITH SOME MIXING POSSIBLE AND LOWERED TEMPERATURES A BIT. THURSDAY
HAS A BREAK IN THE WEATHER WITH AGAIN BOTH MODELS SHOWING ANOTHER
WAVE FOR FRIDAY. THIS SYSTEM DOES NOT LOOK SIGNIFICANT SO WOULD
ONLY EXPECT SPOTTY SNOW SHOWERS WITH LITTLE ACCUMULATION.
SATURDAY LOOKS LIKE A NICE DAY AS A RIDGE MOVES OVER THE REGION
AND HAVE ELIMINATED CHANCE OF SNOW FOR THE MOUNTAINS. MODELS
CARRYING THE NEXT SYSTEM SOUTHWEST OF THE AREA WITH THE ECMWF
SHOWING SOME SOUTHWEST DIFFLUENT FLOW FOR THE MOUNTAINS WHILE THE
GFS HAS MORE OF A MOUNTAIN OROGRAPHIC FLOW LOOK TO IT. EITHER WAY
DRY FOR THE PLAINS AND KEEPING SOME SNOW FOR THE MOUNTAINS.
CONFIDENCE DECREASES FOR EARLY NEXT WEEK BUT NO SIGNIFICANT
WEATHER MAKERS EXPECTED.
SEASONAL TEMPERATURES LOOK LIKELY THROUGH THE PERIOD WITH NORMAL
HIGH TEMPERATURES THIS TIME OF YEAR IN THE LOWER 40S AND LOWS IN
THE 20S. BORSUM
&&
.AVIATION...
WIDELY SCATTERED RAIN AND SNOW SHOWERS WILL BE OVER THE AREA THIS
AFTERNOON...MAINLY FROM KBIL TO KSHR E. MVFR CONDITIONS WILL
ACCOMPANY SOME OF PRECIPITATION. IN ADDITION...OCCASIONAL MVFR
CEILINGS WILL OCCUR W OF KBIL TO KSHR. EXPECT AREAS OF MOUNTAIN
OBSCURATION AS WELL. THE WIDELY SCATTERED SHOWERS WILL END THIS
EVENING...BUT OCCASIONAL MVFR CEILINGS WILL BE LIKELY ACROSS THE
AREA TONIGHT...ALONG WITH AREAS OF MOUNTAIN OBSCURATION. A SLIGHT
CHANCE OF RAIN AND SNOW SHOWERS WILL MOVE OVER THE AREA FROM W TO E
ON TUE MORNING WITH POSSIBLE MVFR CONDITIONS. EXPECT AREAS OF
MOUNTAIN OBSCURATION AS WELL. ARTHUR
&&
.PRELIMINARY POINT TEMP/POPS...
TDY TUE WED THU FRI SAT SUN
-------------------------------------------------------
BIL 042 024/039 020/038 022/042 025/043 024/040 021/040
2/W 13/W 30/B 00/B 12/W 11/B 01/B
LVM 042 018/036 017/035 018/041 021/040 022/037 021/037
1/B 14/J 41/B 00/B 12/J 11/B 11/E
HDN 042 022/040 021/039 020/042 020/043 021/042 019/042
2/W 12/W 31/B 00/B 12/J 11/B 01/B
MLS 042 021/038 018/037 021/040 021/041 021/040 020/040
2/W 12/J 21/B 00/B 11/B 11/B 11/B
4BQ 042 021/039 019/035 020/039 020/042 020/041 019/041
2/W 12/J 32/J 00/B 12/J 11/U 01/B
BHK 040 020/036 017/036 019/036 017/040 018/037 017/037
2/W 11/B 21/B 00/B 01/B 11/U 01/B
SHR 040 018/037 017/036 017/040 018/042 018/040 018/040
2/W 13/J 61/B 11/B 12/J 21/U 11/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
302 PM CST MON FEB 13 2012
.SHORT TERM...TONIGHT THROUGH THURSDAY.
REGIONAL MOSAIC 88D AND SATL PIX SHOWING NARROW LIGHT BAND SNOW
THROUGH NORTHWEST IOWA/CENTRAL NEB/NORTH CENTRAL KS ASSOCIATED WITH
UPPER DEFORMATION ZONE AND SUBTLE POCKET OF UPGLIDE. HIGH RES HRRR
AND RUC SHOWING THAT SNOW ACTIVITY SHOW BE OUT OF THE CWA BY LATE
THIS AFTERNOON.
MODELS IN VERY GOOD AGREEMENT THAT LARGE SCALE FLOW WILL CONSIST OF A
BROAD TROF PREVAILING ACROSS THE CONUS WITH SEVERAL EMBEDDED
SHORTWAVE MIGRATING THROUGH. FOR OUR AREA...SHORTWAVE OF PARTICULAR
INTEREST WAS CURRENTLY DIGGING DOWN THE WEST COAST AND SHOULD BOTTOM
OUT OVER THE FOUR CORNERS REGION TUESDAY...THEN LIFT INTO THE CENTRAL
PLAINS ON WEDNESDAY WITH DPVA INDUCING SURFACE CYCLOGENESIS IN TX
PANHANDLE. MODELS ALSO ADVERTISE STOUT MOISTURE ADVECTION WRAPPING
INTO THE SYSTEM. EXPECT AREAL COVERAGE OF PCPN WILL INCREASE AS IT
EXPANDS NORTHWARD THROUGH THE DAY. GIVEN TRACK OF BEST DYNAMIC
FORCING...HAVE HIGHEST POPS TO THE SOUTH. PCPN TYPE WILL BE HARD TO
PIN DOWN. BUFKIT SHOWING LOW LEVEL THERMAL STRUCTURE IN FLUX WITH
POSSIBLE MIX OF FREEZING RAIN/SNOW AT ONSET OF MORNING PCPN. SYSTEM
IS PROGGED TO SWEEP THROUGH QUICKLY AND PCPN SHOULD BE COMING TO
AN END WEDNESDAY EVENING. NO SIGNIFICANT SNOW ACCUMULATIONS EXPECTED.
DEE
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY.
QUIET AND DRY CONDITIONS EXPECTED THROUGH THE WEEKEND DESPITE
FAST/ACTIVE NWRLY FLOW THANKS TO LIMITED AVAILABLE MOISTURE. UPPER
RIDGING BUILDS OVER THE AREA LATE IN THE WEEKEND WHICH SHOULD HELP
TEMPS RISE INTO THE LOWER 40S. A POTENT MID LEVEL WAVE MOVING OUT OF
THE SOUTHWEST IS FORECAST TO MOVE INTO THE REGION MONDAY INTO
TUESDAY. STRENGTH AND TIMING ARE STILL UNRESOLVED BUT TEMPS EARLY IN
THE SYSTEM LOOK WARM ENOUGH TO SUPPORT RAIN.
KERN
&&
.AVIATION...18Z TAFS FOR KOFK...KOMA AND KLNK.
A MIX OF IFR AND MVFR CONDS ARE EXPECTED THROUGH THE AFTN AT ALL 3
TAF LOCATIONS. AS A WEAKENING AREA OF LIFT MOVS THROUGH OFK BY MID
AFTN SOME ADDITIONAL -SN WILL BE POSSIBLE THERE...BUT OTHERWISE JUST
SOME PATCHY FZDZ IS EXPECTED AT OMA FOR A COUPLE MORE HOURS WITH DRY
CONDS AT LNK. UNCERTAINTY INCREASES THOUGH TONIGHT AS TO WHETHER FOG
WILL FORM AS THE LOW CLOUDS ATTEMPT TO MOVE OUT. ATTM WILL NOT HIT
THE FOG TO HARD AND CONT TO MONITOR THRU THE AFTN. STRATUS MAY ALSO
TRY AND REDEVELOP THIS EVENING AND INTO THE OVERNIGHT HOURS AT
OMA/LNK...BUT THERE IS A GOOD DEAL OF UNCERTAINTY THERE AS WELL.
REGARDLESS...VFR CONDS SHOULD RETURN AT ALL SITES BY MID MORNING ON
TUE.
BOUSTEAD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORMAN OK
307 PM CST MON FEB 13 2012
.DISCUSSION...
ALTHOUGH STILL SOMEWHAT GUSTY THIS AFTERNOON... WINDS WILL BECOME
LIGHT OVERNIGHT. BUT WITH THESE LIGHTER WINDS... THE REDEVELOPMENT
OF A MOIST BOUNDARY LAYER /AND FRESH SNOW IN SOME LOCATIONS/ WILL
LIKELY LEAD TO FOG DEVELOPMENT OVERNIGHT. THE RUC... HRRR AND NAM
ARE VERY AGGRESSIVE WITH FOG DEVELOPMENT OVERNIGHT AND A FOG
ADVISORY OR EVEN A FREEZING FOG ADVISORY MAY BE NEEDED
TONIGHT/TUESDAY MORNING BUT WILL NOT ISSUE WITH THIS PACKAGE YET.
WARMING TEMPERATURES ARE EXPECTED OVER THE NEXT COUPLE OF DAYS.
NEXT STORM SYSTEM WILL MOVE THROUGH THE PLAINS ON WEDNESDAY WITH
PRECIP MOVING EAST FOLLOWED BY GUSTY SOUTHWEST WINDS BEHIND A
DRYLINE. LATER IN THE FORECAST... HAVE ADDED LOW POPS FRIDAY
NIGHT WITH SOME QPF SIGNAL FROM BOTH GFS AND ECMWF... BUT
OTHERWISE NO SIGNIFICANT CHANGES HAVE BEEN MADE TO THE EXTENDED
PERIODS.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 28 58 41 60 / 0 0 20 50
HOBART OK 26 54 39 61 / 0 0 10 20
WICHITA FALLS TX 33 65 46 69 / 0 0 30 40
GAGE OK 19 57 34 57 / 0 0 10 10
PONCA CITY OK 21 50 40 58 / 0 0 20 60
DURANT OK 35 57 50 70 / 0 0 30 70
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
01/01
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1209 PM CST MON FEB 13 2012
.UPDATE...
TEMPS EXPECTED TO HOLD FAIRLY STEADY THROUGH THE AFTERNOON. SURFACE
OBS INDICATING VERY DRY AIR IN NORTHEAST HALF OF CWA WITH DEWPOINTS
MOSTLY IN THE SINGLE DIGITS. AREA OF SNOWFALL ADVANCING
NORTHEASTWARD...WITH TIMING GENERALLY ON TRACK WITH PREVIOUS
FORECAST. THE SNOW WILL HAVE TO OVERCOME THE DRY AIR...BUT OBS
SUGGEST IT WILL DO SO FAIRLY QUICKLY ONCE OVERHEAD. 1200Z NAM/GFS
QPF ALONG WITH MORNING HRRR REFLECTIVITY/QPF SUPPORTED CATEGORICAL
POPS FOR THE LATE AFTERNOON PERIOD. STILL EXPECTING AROUND AN INCH
THIS AFTERNOON IN THE SOUTHWEST...AND A DUSTING NORTHEAST.
&&
.AVIATION/18Z TAFS/...
SNOW CURRENTLY MOVING INTO SOUTHERN WISCONSIN FROM THE SOUTHWEST.
DID NOT MAKE MANY CHANGES TO TAFS...WITH EVERYTHING LOOKING MAINLY
ON TRACK. PERIOD OF MORE MODERATE SNOWFALL WILL LIKELY BE FROM MID
AFTERNOON INTO EARLY EVENING...WITH LIGHT SNOW THEN LINGERING
THROUGH THE NIGHT INTO TUESDAY MORNING. TOTAL SNOW AMOUNTS STILL
EXPECTED TO BE AROUND AN INCH...GIVE OR TAKE A HALF AN INCH.
MODEL SOUNDINGS STILL INDICATING THE POSSIBILITY FOR FREEZING
DRIZZLE LATER TONIGHT INTO THE MORNING...THOUGH CHANCE SEEMS TOO
SMALL TO MENTION IN TAFS FOR NOW.
CONDITIONS WILL LIKELY LOWER TO IFR AS THE MORE MODERATE SNOW
MOVES IN...WITH IFR/MVFR CIGS PROBABLY HANGING AROUND FOR MUCH OF
TUESDAY.
&&
.PREV DISCUSSION... /ISSUED 333 AM CST MON FEB 13 2012/
TODAY AND TONIGHT...FORECAST CONFIDENCE MEDIUM TO HIGH
SNOW UNDER ENHANCED CLOUDS ON IR SATELLITE LOOPS FROM EASTERN
OKLAHOMA UP INTO SOUTHEAST NEBRASKA RIDING CONVERGENCE ON NOSE OF
30-50KT LOW-LEVEL JET...AHEAD OF SHORT WAVE TROUGH IN EASTERN
COLORADO. CURRENT PRECIPITATION IS IN REGION OF STRONG 850-700MB
Q-VECTOR CONVERGENCE AND NARROW AXIS OF INCREASING MOISTURE/LOW TO
MID 20F DEW POINTS/ AS GULF MOISTURE IS TAPPED BY SOUTHERLY FLOW
BETWEEN SPRAWLING SURFACE HIGH CENTERED ON MS/AL BORDER AT 07Z AND
DEVELOPING SURFACE LOW IN EASTERN COLORADO.
MODELS WEAKEN THESE LOW LEVEL WINDS AS THEY APPROACH THE WESTERN
GREAT LAKES...WITH THE NAM AND ECMWF KEEPING THE 30+ KNOT LOW-LEVEL
WINDS AND ASSOCIATED 850 MB CONVERGENCE MAINLY TO THE SOUTH OF THE
STATE THOUGH BRUSHING SOUTHERN WISCONSIN BETWEEN 18Z AND 00Z...WHILE
GFS BRINGS CONVERGENCE FARTHER NORTH INTO THE STATE.
OMEGA ON SOUNDINGS IS WEAK OVERALL...AND MAINLY DUE TO DIFFERENTIAL
CVA AHEAD OF VORTICITY MAXIMA AND 700MB WARM AIR ADVECTION LIFTING
INTO SOUTHERN WISCONSIN...AS WE ARE ACTUALLY COLD ADVECTING AT 850
MB. THIS REFLECTED IN BETTER 700MB AND ABOVE LAYER Q-VECTOR
CONVERGENCE OVER SRN WI...WHILE THE STRONGER 850-700MB Q-VECTOR
CONVERGENCE REMAINS IN CENTRAL/SRN IL.
LIFT OVER WISCONSIN IS FURTHER AIDED BY BROAD AREA OF WEAK UPPER
DIVERGENCE DUE TO DIFFLUENT FLOW AHEAD OF TROUGH THIS AFTERNOON AND
INTO THE EVENING. LIFT WILL BE SUFFICIENT TO ACT WITH INCREASING
DEEP LAYER MOISTURE...AS THE MID-20 DEW POINTS MOVE INTO THE REGION
AND OVERCOME INITIALLY VERY DRY LOW LAYERS...TO PRODUCE A RATHER
PROLONGED PERIOD OF LIGHT SNOW THOUGH ACCUMULATIONS WILL MAINLY
OCCUR IN THE MIDDLE 3 OR 4 HOURS WITH BETTER OMEGA.
WITH SNOW/LIQUID RATIOS BETWEEN 13:1 AND 15:1 DURING THE EVENT AND
QPF FROM AROUND 0.05 INCH IN THE FAR NORTHEAST TO AROUND 0.10 IN THE
SOUTHWEST...SNOW TOTALS WILL RANGE FROM AROUND 1/2 INCH IN THE
NORTHEAST...TO AROUND 1 INCH IN A CORRIDOR CENTERED FROM KENOSHA TO
MADISON TO THE DELLS...WITH BETWEEN 1 INCH AND 1.5 INCHES TO THE
SOUTHWEST OF THE ONE INCH CORRIDOR. MOST OF THESE ACCUMULATIONS WILL
BE REACHED BY 06Z.
WHILE NOT AS MUCH FILTERED SUNSHINE AS ORIGINALLY EXPECTED IN THE
SOUTHWEST...STILL SOME WEAK MORNING SUN NORTHEAST AND EAST TO BRING
HIGHS INTO THE MID 30S BEFORE THE SNOW BEGINS...WHILE THE WEST WILL
SEE MAINLY LOWER 30S.
TOP-DOWN PRECIPITATION TYPE METHODOLOGY SUGGESTS A POTENTIAL FOR
FREEZING DRIZZLE AFTER 06Z TO 09Z IN THE SOUTHEAST AS WEAK 700 MB
DRY PUNCH DRIES OUT THE DENDRITE GROWTH ZONE...WHICH IS AT/ABOVE
700 MB. LOW CONFIDENCE BUT WILL ADD A SLIGHT CHANCE OF FZDZ AFTER
09Z IN SOUTHEAST. CLOUDS AND ABSENCE OF COLD ADVECTION WITH WEAK
SURFACE TROUGH AXIS NOT PASSING THROUGH REGION UNTIL TUESDAY MORNING
WILL KEEP TEMPERATURES IN THE UPPER 20S MOST OF THE NIGHT...WITH A
DIP INTO THE MID 20S JUST BEFORE DAWN.
SHORT TERM...TUESDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE
MEDIUM.
NAM/GFS/CANADIAN MODELS SHOWING SOME LIGHT QPF LINGERING ACROSS
THE AREA DURING THE MORNING ON TUESDAY...AS VORTICITY MAXIMUM
SHIFTS EAST THROUGH THE AREA. FAIRLY DEEP MOISTURE SEEN ON
FORECAST SOUNDINGS DURING THIS TIME...SO KEPT POPS GOING. DENDRITE
ZONE LOSES SATURATION...SO POTENTIAL FOR LIGHT FREEZING DRIZZLE
EXISTS DURING THE MORNING. DRIER AIR WORKING INTO THE AREA DURING
THE AFTERNOON SHOULD BRING AN END TO THE LIGHT SNOW/LIGHT FREEZING
DRIZZLE.
ANOTHER SHORTWAVE TROUGH PUSHING THROUGH THE REGION LATE TUESDAY
AND TUESDAY NIGHT SHOULD BRING SOME MID LEVEL CLOUDS. NAM HOLDS
ONTO LOW LEVEL MOISTURE TUESDAY THROUGH MOST OF WEDNESDAY...WITH
THE GFS NOT SHOWING THIS LAYER. WEAK LOW LEVEL WARM AIR ADVECTION
ON WEDNESDAY WOULD HELP ANY LOW LEVEL MOISTURE LINGER. INCREASED
CLOUD COVER FOR TUESDAY THROUGH WEDNESDAY. THIS WILL AFFECT
TEMPERATURES DURING THIS TIME...AND KEPT HIGHS TUESDAY AND
WEDNESDAY IN THE MID TO UPPER 30S...AND INCREASE LOWS TUESDAY
NIGHT IN THE MID 20S TO AROUND 30.
LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY...FORECAST CONFIDENCE
MEDIUM.
MAIN ISSUE IS POTENTIAL FOR ACCUMULATING SNOW WEDNESDAY NIGHT AND
THURSDAY ACROSS THE AREA. GFS/ECMWF GENERALLY SHOWING LOW PRESSURE
MOVING FROM THE SOUTHERN PLAINS LATE WEDNESDAY TO FAR NORTHWEST
INDIANA BY 12Z THURSDAY. THE CANADIAN HAS THE LOW FURTHER INTO FAR
EASTERN IOWA AT 12Z THURSDAY...WITH THE NAM SLOWER AND OVER
NORTHEAST ILLINOIS. THESE LOW POSITIONS REFLECT THE POSITIONS OF
THE NEGATIVELY TILTED SHORTWAVE TROUGH IN EACH OF THE MODELS. WILL
FOLLOW THE ECMWF/GFS MOVEMENT OF THIS SYSTEM.
ORGANIZED MID LEVEL FRONTOGENESIS RESPONSE BAND PUSHES SOUTHWEST
TO NORTHEAST ACROSS THE FORECAST AREA WEDNESDAY NIGHT...HELPING
ENHANCE UPWARD VERTICAL MOTION ACROSS THE AREA. GOOD AMOUNT OF QPF
MOVES THROUGH WEDNESDAY NIGHT...WITH GRADUALLY LOWER AMOUNTS
THURSDAY AS SYSTEM MOVES OFF TO THE EAST. MILD AIR OVER THE
SOUTHEASTERN COUNTIES WEDNESDAY NIGHT INTO THURSDAY WILL ALLOW
FOR A MIX OF RAIN AND SNOW...REDUCING SNOWFALL ACCUMULATIONS
THERE. GIVEN THE EXPECTED QPF AMOUNTS...SNOW ACCUMULATIONS OF 2 TO
4 INCHES APPEAR LIKELY ACROSS MOST OF THE AREA. THE FAR SOUTHEAST
WILL SEE LOWER AMOUNTS WITH THE MILDER AIR ALLOWING FOR A MIX.
KEPT LIKELY POPS IN THE SOUTH AND EAST FOR MOST OF THIS PERIOD.
QUIET WEATHER FOR THE REST OF THE EXTENDED PERIOD...SO FOLLOWED
CONSENSUS POPS AND TEMPERATURES.
AVIATION/12Z TAFS/...
CIRRUS AHEAD OF APPROACHING TROUGH CURRENTLY SPREADING INTO
REGION...WITH CLOUDS TO THICKEN AND SLOWLY LOWER THROUGH THE
MORNING. VFR CIGS UNTIL MIDDAY WITH NOTHING LOWER THAN 4K FT...THEN
A RAPID DROP TO MVFR AROUND 1400 TO 1500 FEET FROM WEST TO EAST
AFTER 18Z ALONG WITH LIGHT SNOW. VISIBILITIES MAINLY 3-5 MILES WITH
THE LIGHT SNOW...THOUGH AN OCCASIONAL 1-2SM DURING THE MID TO LATE
AFTERNOON AT KMSN AND LATE AFTERNOON/EVENING AT EASTERN TAF SITES
WHEN ACCUMULATIONS ARE MOST LIKELY. ONLY LOOKING AT AROUND AN INCH
AT TAF SITES WITH THESE TOTALS BEING REACHED BY 06Z. SOME
INDICATIONS OF PATCHY FREEZING DRIZZLE...ESPECIALLY AT THE EASTERN
TAF SITES AFTER 09Z TUESDAY...BUT TOO LOW A CHANCE TO MENTION AT
THIS TIME.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...WIMBERLEY/DDV
TODAY/TONIGHT AND AVIATION/MARINE...REM
TUESDAY THROUGH SUNDAY...WOOD
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1144 AM CST MON FEB 13 2012
.SHORT TERM...TODAY THROUGH THURSDAY
257 AM CST MON FEB 13 2012
MAIN FORECAST CONCERNS ARE ON SNOW FOR TODAY AND TONIGHT...THEN A
SYSTEM TO WATCH FOR WEDNESDAY THROUGH THURSDAY.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS
SHOWED RIDGING OVER SOUTH CENTRAL CANADA...SHORTWAVE TROUGHING
DROPPING INTO NORTHERN CALIFORNIA...A BROAD TROUGH ACROSS THE
CENTRAL AND SOUTHERN PLAINS...AND RIDGING UP AND DOWN THE
MISSISSIPPI RIVER VALLEY. THE FORECAST AREA REMAINS IN SUBSIDENCE
UNDER THE UPPER RIDGE...AS WELL AS IN AN AXIS OF DRY AIR ASSOCIATED
WITH A RIDGE OF HIGH PRESSURE AT THE SURFACE. A LAPS SOUNDING OVER
LA CROSSE AT 08Z DEPICTED A VERY DRY SOUNDING WITH PRECIPITABLE
WATER VALUE OF 0.08 INCHES. THIS DRY AIR KEPT SKIES MAINLY CLEAR IN
THE EVENING...BUT NOW MID LEVEL CLOUDS ARE STREAMING TO AREAS WEST
OF THE MISSISSIPPI RIVER. OAX 00Z RAOB AND 04Z TAMDAR SOUNDING
SHOWED A SATURATED LAYER BETWEEN 725-825MB...REFLECTING THE MID
LEVEL CLOUDS. RADAR LOOP AND SURFACE OBS SHOW THE EASTERN EDGE OF
PRECIPITATION...ASSOCIATED WITH MOISTURE TRANSPORT AND DPVA AHEAD OF
THE CENTRAL PLAINS TROUGH...NOW INTO WESTERN IOWA. PRECIPITABLE WATER
VALUES DEFINITELY HIGHER OVER THE CENTRAL PLAINS...THANKS TO A
SOUTHERLY LOW LEVEL JET OUT OF THE GULF OF MEXICO. 00Z RAOBS SHOWED
VALUES BETWEEN 0.4 AND 0.5 INCHES AT DDC...OUN AND AMA.
TODAY AND TONIGHT...TROUGHING OVER THE CENTRAL AND SOUTHERN PLAINS
IS PROGGED TO CONTINUE TRACKING EASTWARD THROUGH TONIGHT...MOVING
THROUGH THE OHIO VALLEY AND SORT OF SHEARING OUT AS IT TRIES TO GET
THROUGH THE RIDGING. AS A RESULT...FORCING FOR THIS TROUGH IS
STRONGEST TODAY AND THEN WEAKENS TONIGHT. 500MB HEIGHT FALLS IN 12
HOURS PROGGED BETWEEN 50-70 METERS OVER THE FORECAST AREA...GREATEST
BETWEEN 18-06Z. THEREFORE...JUST FROM FORCING THIS LOOKS TO BE THE
BEST POTENTIAL FOR PRECIPITATION. MOISTURE TRANSPORT AND ISENTROPIC
LIFT PLOTS STILL LOOK TERRIBLE IN TERMS OF THIS KIND OF FORCING...
WITH MOST OF IT FOCUSED SOUTH OF I-80. STILL...THE HEIGHT FALLS
ACTING ON THE MOISTURE BEING BROUGHT UP OUT OF THE GULF OF MEXICO
SHOULD BE ENOUGH TO SPREAD LIGHT SNOW ACROSS THE AREA. TIMING VARIES
ON MODEL...LIKELY DUE TO UNCERTAINTY ON HOW FAST THE DRY AIR CAN
ERODE. THE 13.00Z GFS AND 12.21Z SREF MEANS ARE FASTEST SPREADING IT
NORTHEAST...WHILE THE 13.00Z NAM/ECMWF ARE A LITTLE SLOWER. IN FACT
IN THIS LATTER GROUP...THEY KEEP PRECIPITATION ENTIRELY ALONG AND
SOUTH OF I-94 BEFORE 00Z. FOR NOW STAYED WITH A COMPROMISE...IN
AGREEMENT WITH THE LATEST HRRR RUNS WHICH HAVE BEEN DOING WELL THUS
FAR. THIS RESULTS IN THE FORECAST ENDING UP PRETTY SIMILAR TO WHAT
HAS BEEN FORECAST THE PAST FEW DAYS FOR PRECIPITATION CHANCES. SNOW
STILL LOOKS TO DIMINISH AFTER 06Z AS THE TROUGH WEAKENS AND MOVES
EAST OF THE AREA. VERY GOOD MODEL AGREEMENT ON QPF TODAY AND LOOKS
REASONABLE GIVEN HEIGHT FALLS THE ONLY FORCING. TOTAL SNOWFALL
AMOUNTS STILL LOOKING IN THAT 0.5-2 INCH RANGE WITH SNOW TO WATER
RATIOS BETWEEN 10-15 TO 1. HIGHEST SNOW AMOUNTS SOUTH OF I-90. ON A
PRECIPITATION TYPE SIDE NOTE...THERE ARE SOME HINTS THIS EVENING OF
A POSSIBLE LOSS OF ICE IN THE GRANT COUNTY AREA. HARD TO SAY WITH
THE MOISTURE INTERSECTING AT -10/-11C...WHICH SHOULD BE ABLE TO KEEP
IT AS SNOW...SO NO FREEZING DRIZZLE MENTIONED AT THIS TIME.
REGARDING CLOUD COVER...SHOULD SEE CLOUDS SPREAD NORTHEAST ACROSS
THE AREA THIS MORNING...THEN STAY IN PLACE THROUGH TONIGHT. THESE
CLOUDS WILL LIMIT TEMPERATURE FALL TONIGHT GIVEN LACK OF COLD
ADVECTION...PROBABLY ONLY FALLING ABOUT 5 DEGREES FROM TODAYS
HIGHS. AS FOR TODAYS HIGHS...INCREASING SOUTHERLY FLOW WILL ADVECT
WARMER AIR INTO THE AREA. A BLEND OF GUIDANCE SEEMS REASONABLE.
TUESDAY AND TUESDAY NIGHT...IN THE WAKE OF TODAY AND TONIGHTS
TROUGH...MODELS SHOW ANOTHER WEAK SHORTWAVE CROSSING THE FORECAST
AREA TUESDAY EVENING. THIS SHORTWAVE CAN BE SEEN ON WATER VAPOR OVER
NORTH DAKOTA. VERY LITTLE GOING ON WITH IT AND MODELS SUGGEST THE
SAME WHEN IT COMES ACROSS. PLUS...THE SHORTWAVE DOES NOT HAVE MUCH
FORCING OR MOISTURE TO WORK WITH. THEREFORE...THE DRY FORECAST
DURING THIS PERIOD STILL SEEMS REASONABLE. CLOUDS SHOULD TAKE AWHILE
CLEARING...THOUGH...DUE TO A LACK OF ANY STRONG SUBSIDENCE. THERE IS
A WESTERLY WIND PUSH OF SOME DRIER AIR FROM THE PLAINS ON
TUESDAY...BUT THERE ARE HINTS THAT COME TUESDAY EVENING A SURGE OF
800-900MB MOISTURE LIKELY WITH THE SHORTWAVE MOVES IN. THEREFORE
HAVE INCREASED CLOUD COVER. THIS PUTS A CONCERN ON TEMPERATURES. A
SOUTHWEST WIND ON TUESDAY BRINGING IN SOME WARMER AIR SHOULD HELP
TEMPERATURES CLIMB INTO THE LOW TO MID 30S. OF COURSE...IF SUN DOES
DEVELOP...READINGS COULD TOUCH 40. WITH THE IDEA OF MORE CLOUDS
PRESENT TUESDAY NIGHT...DID RAISE LOWS A COUPLE DEGREES.
WEDNESDAY THROUGH THURSDAY...THIS TIME PERIOD HAS BECOME A LITTLE
MORE INTERESTING THIS 13.00Z MODEL CYCLE. A SECOND SHORTWAVE
TROUGH...WHICH IS SEEN RIGHT NOW DIGGING INTO CALIFORNIA...IS
PROGGED TO LIFT NORTHEAST OUT OF THE SOUTHWEST AND EVENTUALLY INTO
LOWER MICHIGAN OR OHIO BY THURSDAY. WITH THIS SHORTWAVE TROUGH
MODELS SHOW A DECENT LOW PRESSURE AREA LIFTING NORTHEAST WITH IT. ON
THE NORTH SIDE IS THE TYPICAL DEFORMATION ZONE OF PRECIPITATION. HOW
FAR NORTH THE SHORTWAVE TROUGH LIFTS AND DEEPENS DEPENDS ON TIMING
AND DISTANCE FROM A NORTHERN STREAM TYPE SHORTWAVE TROUGH DIGGING
INTO THE DAKOTAS. IF THESE TWO CAN MEET UP...WHICH HAS BEEN SHOWN
THE PAST FEW DAYS FROM THE CANADIAN AND SOME ECMWF RUNS...THEN THE
LOW PRESSURE AREA LIFTS FARTHER NORTH. WE COULD BE DEALING WITH AN
ADVISORY TYPE SNOWFALL...AND POSSIBLY RAIN MIXING IN FOR SOME
SOUTHERN LOCATIONS. ON THE OTHER HAND...IF THEY DO NOT MEET UP WHICH
HAS BEEN SHOWN BY SOME PAST GFS/ECMWF RUNS...THE SYSTEM STAYS SOUTH
AND THE FORECAST AREA IS DRY. CERTAINLY TREND IN THE 13.00Z MODEL
CYCLE HAS BEEN FARTHER NORTH AND FASTER...SO HAVE ADJUSTED THE
FORECAST THIS WAY. DID NOT GO COMPLETELY WITH THE 13.00Z
GFS/ECMWF/CANADIAN...THOUGH...BECAUSE THE GFS ENSEMBLES STILL SHOW
QUITE A BIT OF SPREAD. PLUS...MODEL CONSISTENCY HAS NOT BEEN THE
BEST. CHANGES THIS FORECAST INCLUDE BRINGING LOW PRECIPITATION
CHANCES INTO NORTHEAST IOWA WEDNESDAY AFTERNOON...RAISING CHANCES
10-20 PERCENT WEDNESDAY NIGHT...THEN ENDING MOST OF THE
PRECIPITATION FOR THURSDAY AFTERNOON. AN ADDITIONAL CHANGE IS
RAISING LOWS 3-5 DEGREES WEDNESDAY NIGHT...BUT THESE ARE TRICKY. IF
MORE SUN IS OBSERVED WEDNESDAY...THE LOWS MAY NEED TO BE RAISED
FURTHER. THE SAME WOULD OCCUR WITH A FARTHER NORTH TRACK. NEEDLESS
TO SAY...A LOT TO BE IRONED OUT.
.LONG TERM...THURSDAY NIGHT THROUGH SUNDAY NIGHT
257 AM CST MON FEB 13 2012
13.00Z ECMWF/CANADIAN/GFS AND GFS ENSEMBLES REMAIN IN DISAGREEMENT
ON A LOT OF THE LONG TERM PERIOD WITH REGARDS TO INDIVIDUAL
SHORTWAVE DETAILS. AGAIN...THIS IS PROBABLY RELATED TO FAST...ZONAL
PACIFIC FLOW RUNNING INTO A SPLIT FLOW PATTERN OVER NORTH AMERICA.
STILL...DESPITE THE DIFFERENCES...THERE IS GOOD AGREEMENT THAT THE
GULF OF MEXICO WILL BE CUT-OFF FROM BRINGING MOISTURE BACK NORTHWARD
UNTIL SOMETIME EARLY NEXT WEEK. THE MOISTURE CUT-OFF IS DUE TO THE
WEDNESDAY NIGHT/THURSDAY SYSTEM...WHICH ALLOWS A DRIER HIGH PRESSURE
AREA TO MOVE DOWN TO THE GULF COAST. THEREFORE...THE ENTIRE LONG
TERM FORECAST REMAINS DRY. 850MB TEMPS ARE HINTED TO BE SLIGHTLY
COOLER FOR FRIDAY AND SATURDAY COMPARED TO THE PREVIOUS
FORECAST...DUE TO SOME SEMI-DECENT AGREEMENT ON NORTHERN STREAM
TROUGHING AFFECTING THE FORECAST AREA DURING THIS TIME.
HOWEVER...READINGS ARE STILL LIKELY TO END UP AT OR ABOVE NORMAL FOR
HIGHS AND LOWS WITH A LOT OF THE COLD AIR STAYING WELL NORTH INTO
CANADA. NO REAL STRONG WARM SURGES EITHER DUE TO THE SPLIT FLOW
PATTERN.
&&
.AVIATION...THROUGH 18Z TUESDAY
1143 AM CST MON FEB 13 2012
LOOK FOR AN EXTENDED PERIOD OF -SN THIS AFTERNOON INTO TONIGHT AS
A VIGOROUS MID-LEVEL WAVE OF LOW PRESSURE TRACKS EAST ACROSS THE
REGION. IFR VIS/CIGS WILL BE SEEN AT BOTH KRST/KLSE THIS AFTERNOON
IN -SN. LOOK FOR THE LIGHT SNOW TO TAPER OFF FROM WEST TO EAST
AFTER MIDNIGHT TONIGHT WITH AROUND 2 INCHES OF SNOWFALL WHEN ALL
IS SAID AND DONE AT THE TAF SITES. LINGERING MOISTURE TRAPPED IN
THE LOWER BOUNDARY LAYER BEHIND THE DEPARTING WAVE OF LOW PRESSURE
EXPECTED TO PRODUCE IFR CIGS AND VIS AT KRST...AND IFR CIGS AT
KLSE THROUGH NOON AND POSSIBLY INTO THE AFTERNOON HOURS TUESDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
257 AM CST MON FEB 13 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...DAS