AREA FORECAST DISCUSSION
NWS CHICAGO IL
616 AM CST MON JAN 28 2008
.DISCUSSION...
402 AM CST
UPPER TROUGH DEEPENING ACROSS WESTERN NORTH AMERICA TODAY...WITH
SERIES OF MINOR SHORT WAVES RIPPLING NORTHEAST ALONG PERIPHERY OF
STRONG JET INTO MIDWEST AND NORTHERN GREAT LAKES. SURFACE
PRESSURES CONTINUE TO FALL ACROSS THE PLAINS IN RESPONSE TO JET
AND UPPER TROUGH...STRENGTHENING SOUTHERLY LOW LEVEL FLOW INTO
FORECAST AREA AND DRAWING WARM AIR RAPIDLY NORTH. PROFILER NETWORK
INDICATES 50-60 KNOT SOUTHWEST 850 HPA JET SPREADING FROM TEXAS
PANHANDLE NORTHEAST INTO UPPER MISSISSIPPI VALLEY PROVIDING
IMPRESSIVE WARM ADVECTION AND HIGH CLOUDINESS TO THE REGION...
THOUGH REGIONAL RADAR MOSAIC INDICATES LITTLE ORGANIZED
PRECIPITATION. 00Z RAOB ANALYSIS INDICATES WHY...WITH 15-20
DEGREE DEW POINT DEPRESSIONS IN 925-850 HPA LAYER IN LOW LEVEL JET
SOURCE REGION. SHORT TERM MODEL GUIDANCE DOES INDICATE SATURATION
WILL EVENTUALLY OCCUR ACROSS THE AREA LATER TODAY...BUT HAVE
REMOVED MENTION OF SHOWERS FOR THIS MORNING. SOUTHERN CALIFORNIA
SHORT WAVE LIFTS ACROSS REGION THIS EVENING WITH 850 HPA WARM
FRONT PUSHING NORTHEAST OF AREA OVERNIGHT...THUS EXPECT SHOWER
COVERAGE TO BE HIGHEST DURING EVENING...THEN DECREASE SOMEWHAT
OVERNIGHT AS STRONGER FORCING MOVES NORTHEAST OF FORECAST AREA.
BIGGER CHALLENGE PERHAPS TODAY AND TONIGHT ARE TEMPERATURES...WITH
BATTLE BETWEEN STRONG LOW LEVEL THERMAL ADVECTION AND REMAINING
SNOW COVER ACROSS ESPECIALLY FAR NORTHERN IL. LOW LEVEL PARCEL
TRAJECTORIES AND MODEL FORECAST 950 HPA TEMPS INDICATE 50S
POSSIBLE ACROSS SOUTHERN PARTS OF CWA AND HAVE GENERALLY GONE
ABOVE GUIDANCE TEMPS THERE...THOUGH HAVE STAYED CLOSER TO GUIDANCE
IN MID 40S FARTHER NORTH WHERE RECEDING SNOW COVER WILL HAVE
SOME EFFECT. WITH SURFACE PRESSURE GRADIENT MAINTAINING STRONG
SOUTH WINDS OVERNIGHT...APPEARS ALL MOS GUIDANCE MUCH TOO COOL
WITH OVERNIGHT MINS.
MAIN UPPER TROUGH PUSHES TOWARD AREA ON TUESDAY...WITH STRONG
HEIGHT FALLS DEVELOPING ACROSS THE AREA DURING THE DAY.
COMBINATION OF STRONG LOW LEVEL FRONTOGENESIS AND FAVORABLE LEFT
EXIT REGION OF UPPER JET STREAK SUPPORT MODEL DEPICTIONS OF DEEP
VERTICAL MOTION DURING THE PERIOD...WITH STEEPENING MID LEVEL
LAPSE RATES AND LOW LEVEL MOIST AXIS AHEAD OF COLD FRONT
INCREASING POTENTIAL FOR CONVECTION. WRF AND GFS BOTH DEPICT WEAK
ELEVATED CAPE FOR PARCELS JUST BELOW 850 HPA TUESDAY MORNING THUS
WILL MAINTAIN MENTION OF ISOLATED THUNDER. APPEARS FROPA WILL
OCCUR BY MIDDAY AT ROCKFORD...DURING EARLY/MID AFTERNOON IN
CHICAGO AND DURING THE MID/LATE AFTERNOON FOR INDIANA COUNTIES.
MODELS CONTINUE TO DEPICT THICKNESS VALUES FALLING RAPIDLY WITH
FAIRLY QUICK CHANGE FROM RAIN TO SNOW EXPECTED...AND
WEST/NORTHWEST WINDS GUSTING 30 TO 40 MPH. POTENTIAL FOR AN INCH
OR SO OF SNOW TUESDAY AFTERNOON/EVENING...THOUGH WINDS WILL KEEP
IT FROM ACCUMULATING UNIFORMLY AND WILL MENTION BLOWING SNOW AS
WELL. PRECIP TO TAPER OFF FROM WEST TO EAST DURING THE EVENING
WITH SUBSIDENCE AND STRONG LOW LEVEL DRY ADVECTION ALLOWING
DECREASING CLOUDS/CLEARING AS ARCTIC AIR POURS IN. WITH TEMPS
CRASHING INTO SINGLE DIGITS AND EVEN SOME SUBZERO READINGS...GUSTY
WINDS WILL LIKELY SEND WIND CHILL READINGS INTO -20 TO -25 RANGE
ACROSS NORTHERN IL BY EARLY WEDNESDAY MORNING.
STORM EXITS QUICKLY TO THE EAST BY WEDNESDAY WITH WEAK SURFACE
RIDGE MOVING ACROSS THE AREA AND ALLOWING WINDS TO DIMINISH THOUGH
WITH COLD TEMPS CONTINUING BY AFTERNOON. MODELS REMAIN QUITE
SIMILAR IN DIGGING ANOTHER UPPER TROUGH ACROSS THE WEST
HOWEVER...RESULTING IN QUICK RETURN OF LOW LEVEL WARM ADVECTION
ACROSS PLAINS TO OUR WEST WITH AREA OF LIGHT WAA SNOW INDICATED
PERHAPS AS FAR EAST AS NORTHWEST IL/SOUTHERN WI WEDNESDAY NIGHT.
LONGER RANGE GUIDANCE CONTINUES TO DEPICT STRONGER STORM SYSTEM
THURSDAY/FRIDAY...THOUGH SIGNIFICANT DIFFERENCES CONTINUE WITH
RESPECT TO TRACK OF SURFACE LOW. ECMWF CONTINUES TO BE FARTHEST
WEST WITH LOW LIFTING FROM SOUTHERN PLAINS TO SOUTHERN LAKE
MICHIGAN...00Z GFS CONTINUES TO FAVOR A TRACK FARTHER EAST UP THE
OHIO RIVER...WHILE THE GEM IS IN BETWEEN WITH A TRACK MORE ACROSS
OHIO. AT THIS DISTANCE WILL MAINTAIN CHANCE FOR SNOW ACROSS CWA
THURSDAY NIGHT THROUGH FRIDAY AND CONTINUE TO HIGHLIGHT POTENTIAL
FOR WINTER STORM SOMEWHERE NEARBY IN HAZARDOUS WEATHER OUTLOOK.
RATZER
&&
.AVIATION...
615 AM CST
1200 UTC TAFS...MAIN AVIATION CONCERNS TODAY WILL CENTER ON WINDS
AND POTENTIAL OF RAIN SHOWERS THIS AFTERNOON AND EVENING.
SURFACE PRESSURE GRADIENT WILL CONTINUE TO STRENGTHEN TODAY IN
RESPONSE TO DEEPENING LOW PRESSURE ACROSS THE NORTHERN PLAINS.
WIND SPEEDS HAVE BEEN SLOW TO INCREASE DURING THE NIGHT DUE TO A
STRONG LOW LEVEL INVERSION EVIDENT ON ACARS SOUNDINGS. WINDS ALOFT
HAVE BEEN STEADILY INCREASING WITH ACARS SOUNDING AT 09Z
INDICATING LOW LEVEL WIND SHEAR CRITERIA BEING MET IN A LAYER
FROM APPROX 1100-1400 FT. BEFORE LOW LEVEL INVERSION BEGINS TO
WEAKEN A BIT THIS MORNING...WILL CONTINUE TO CARRY MENTION OF LOW LEVEL
WIND SHEAR THROUGH MID MORNING. AS THIS INVERSION BEGINS TO WEAKEN
SOMEWHAT...WIND SPEEDS SHOULD INCREASE INTO THE 20G30KT
NEIGHBORHOOD BY LATE MORNING. IN TERMS OF SKY COVER...THICKER HIGH
LEVEL CLOUDINESS WILL CONTINUE TO OVERSPREAD NORTHERN ILLINOIS
THIS MORNING. MODEL GUIDANCE HAS BEEN SOMEWHAT CONSISTENT OVER
PAST FEW DAYS IN INDICATING SHOWERS DEVELOPING ACROSS NORTHEAST
ILLINOIS/NORTHWEST INDIANA IN ASSOCIATION WITH STRONG LOW LEVEL
WARM/MOIST ADVECTION. GIVEN STRENGTH OF THIS ADVECTION WITH 55
KNOT LLJ DEVELOPING TODAY...WILL INCLUDE MENTION OF RAIN LATE THIS
AFTERNOON.
WINDY CONDITIONS WILL CONTINUE INTO TONIGHT WITH CHANCE OF RAIN
PERSISTING IN ASSOCIATION WITH AN UPPER LEVEL SHORT WAVE TROUGH
APPROACHING FROM THE PLAINS. THIS SHORT WAVE WILL LIFT NORTHEAST
INTO THE UPPER GREAT LAKES OVERNIGHT WHICH SHOULD DECREASE RAIN
CHANCES TOWARD MIDNIGHT. DID INTRODUCE MVFR CIGS/VSBYS AFT 00Z
TONIGHT IN ASSOCIATION WITH PRECIP...WITH MVFR CIGS/VSBYS LIKELY
LINGERING THROUGH THE OVERNIGHT HOURS.
MARSILI
&&
.MARINE...
315 AM CST
A VERY ACTIVE MARINE PERIOD IN TERMS OF WINDS IS IN STORE FROM TODAY
THROUGH WEDNESDAY. SOUTHERLY SURFACE PRESSURE GRADIENT WILL CONTINUE
TO STRENGTHEN THIS MORNING. WINDS HAVE BEEN A BIT SLOW TO RESPONSE
DUE TO WARM ADVECTION OVER COLD LAKE WATERS...BUT TOWARD MIDDAY
EXPECTING SOUTH GALES TO BECOME PREVALENT. IT APPEARS AS THROUGH
STRONGEST WINDS TO AROUND 40 KNOTS WILL OCCUR IN THE 21Z-06Z TIME
FRAME...WITH WINDS SLOWLY DECREASING OVERNIGHT AND INTO TUESDAY
MORNING. BY TUESDAY MORNING...A TROUGH OF LOW PRESSURE WILL BE
APPROACHING LAKE MICHIGAN WITH A WEAKENING SFC PRESSURE GRADIENT
THAT SHOULD ALLOW SOUTHWEST WINDS TO DROP INTO THE 15 TO 25 KNOT
RANGE. THIS LULL IN WIND SPEEDS WILL BE SHORT LIVED AS ANOTHER LOW
PRESSURE AREA DEVELOPS ACROSS THE CENTRAL PLAINS AND APPROACHES LAKE
MICHIGAN TUESDAY AFTERNOON. AN ARCTIC AIR MASS WILL SPREAD OVER THE
REGION IN THE WAKE OF THIS LOW PRESSURE ON TUESDAY EVENING...AND
ANOTHER PERIOD OF GALES IS EXPECTED LATE TUESDAY AFTERNOON INTO
TUESDAY NIGHT FROM THE WEST NORTHWEST. SFC GRADIENT SHOULD SUPPORT
CONTINUED GALES INTO WEDNESDAY MORNING ACROSS THE NORTH HALF OF THE
LAKE. A RIDGE OF HIGH PRESSURE WILL BUILD IN BEHIND THE DEPARTING
LOW PRESSURE AREA LATE WEDNESDAY...ALLOWING FOR WINDS AND WAVES TO
SUBSIDE. LATE WEEK PERIOD SHOULD FEATURE EAST NORTHEAST WINDS AS LOW
PRESSURE DEVELOPS ACROSS THE SOUTHERN PLAINS AND AS THE RIDGE OF
HIGH PRESSURE DEPARTS TO THE EAST.
IN TERMS OF HEADLINES...WILL EXTEND GALE WARNING FOR NEARSHORE AND
OPEN WATERS TO COVER THE EXPECTED SOUTH GALES TODAY/TONIGHT...AND
THEN WEST GALES LATE TUESDAY AFTERNOON THROUGH EARLY WEDNESDAY.
MARSILI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING FROM 9 AM THIS MORNING TO 6 AM CST WEDNESDAY FOR
LMZ740>745-777-779.
&&
$$
WFO LOT
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
835 AM EST MON JAN 28 2008
.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER THE AREA TODAY. THE HIGH WILL DRIFT
OFF THE COAST EARLY TUESDAY ALLOWING FOR A COLD FRONT TO MOVE THROUGH
THE REGION TUESDAY NIGHT.
HIGH PRESSURE WILL BUILD IN BEHIND THIS FRONT FOR WEDNESDAY AND
THURSDAY. THE NEXT STORM SYSTEM WILL ARRIVE THURSDAY NIGHT AND
FRIDAY. HIGH PRESSURE WILL RETURN FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WATER VAPOR LOOP SHOWS UPPER LOW MOVING NORTHEAST OVER NEW ENGLAND
WATERS. MEANWHILE...RIDGING IS BUILDING IN FROM THE MIDWEST...AHEAD
OF A WEST COAST TROUGH. ACARS 400-250MB WIND OBSERVATIONS REVEAL
NORTHWESTERLY FLOW ALOFT ON PERIPHERY OF UPPER RIDGE. A 125-150KT
JET IS EXITING THE WEST COAST TROUGH ACROSS THE ROCKIES. 11Z SURFACE
ANALYSIS PLACED AN OCCLUDED CYCLONE WELL OFF OF NEW ENGLAND...WITH A
SECONDARY COLD FRONT SINKING SOUTH THROUGH NEW ENGLAND...BECOMING
STATIONARY ACROSS NEW YORK STATE AND WESTERN QUEBEC. A 1024MB
ANTICYCLONE WAS LOCATED ACROSS THE APPALACHIANS...WITH A TROUGH IN
THE LEE OF THE MOUNTAINS.
CORRIDOR OF STRATO-CU...WHICH DEVELOPED AS SUBSIDENCE INVERSION
TRAPPED A THIN LAYER OF MOISTURE LAST NIGHT...IS MOVING TO THE
NORTHEAST AT 5 MPH AS RIDGING BUILDS IN FROM THE WEST. COMBINATION
OF CLOUD MOVEMENT...AND DIURNAL MIXING...SHOULD END UP YIELDING A
MOSTLY SUNNY AFTERNOON ACROSS EASTERN ZONES. FURTHER WEST...EXPECT
SUNSHINE WITH A FEW THIN CIRRUS INVADING FROM THE OHIO VALLEY THIS
AFTERNOON.
AS WARM ADVECTION CONTINUES TO OCCUR...SUNNY LOCATIONS WILL SEE
TEMPERATURES CLIMB NEAR OR ABOVE 50F. TEMPERATURES MAY BE A FEW
DEGREES TOO OPTIMISTIC EAST OF INTERSTATE 95 IF CLOUDS HOLD INTO THE
EARLY AFTERNOON. WINDS BECOME LIGHT AS HIGH PRESSURE BUILDS INTO THE
REGION.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
HIGH OVER THE AREA FOR THE 1ST PART OF NGT...MOVG OFFSHORE OVRNGT.
MDLS ARE GIVING LO CHC POPS TOWARDS TUE MRNG AS A WARM FNT MOVES
INTO THE AREA. I AM A TOUCH SKEPTICAL ON THE PCPN CHCS - RDG STILL
LOOKS ALONG THE CST BY 12Z...SO I`LL STAY W/ OUR CURRENT FCST OF
SLT CHC ALONG THE BLUE RDG BY 12Z TUE. TEMPS MON NGT GNRLY U20S/L30S.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
RAISED TEMPS A FEW DEGREES TUES AFTN W/ INCR PRE-FRONTAL S/RLY
WINDS. EVEN W/ INCR CLOUD COVER AND INCOMING PRECIP...SR MODELS
PLACING A WEAK WARM FRONT...MORE OF A WEAK SFC TROF THO A BAROCLINIC
ZONE REGARDLESS...JUST SOUTH OF MASON/DIXON LINE...ALLOWING FOR
HIGHS NEAR 50 ACROSS THE PIEDMONT...U40S N OF THE BNDRY. NAM/GFS
KEYING IN ON AN ELONGATED BAND OF PRECIP SPREADING NE ACROSS THE CWA
TUES AFTN AND OVERNIGHT. NOT A VERY STRONG SIGNAL OF WAA...SO THE
ISENTROPIC ASCENT WILL BE MINIMAL AND LOWER QPFS SHOULD RESULT FROM
THE BEGINNING. RISING MOTION ALONG THE SFC TROF/BNDRY WILL BE THE
MAIN FORCING...AS SW/RLY WINDS RIDE ALONG THE SLOW MOVING BNDRY.
OVERNIGHT...THE SFC LOW BACK ACROSS THE GREAT LAKES REGION WILL
STRENGTHEN...ALONG W/ A SHARPLY DEEPENING NEGATIVELY TILTED ACROSS
THE EASTERN OHIO RIVER VALLEY. THE RESULTS WILL MOST LIKELY BE A
STRONGER COLD FRONT W/ A MORE NORTH/SOUTH ORIENTATION...WHICH IS
MORE FAVORABLE TO SPREAD PRECIP ACROSS THE MID ATLANTIC WHEREAS THE
HIGHER ELEVATIONS WOULD NORMALLY SCATTER IT OUT BEFORE MAKING IT
INTO THE PIEDMONT. LOW LEVEL WINDS WILL ALSO INCR JUST AHEAD OF A
BEHIND THE FRONT...W/ 20-25KT GUSTS COMMON FOR THIS EVENT. THE
STRONGEST WINDS LOOK TO BE OVERNIGHT AND EARLY WED W/ THE FRONTAL
PASSAGE...MAINLY BEFORE 18Z WED.
ANOTHER LEE TROF OVER THE CENTRAL/SRN PLAINS WILL GEAR UP THE NEXT
SYSTEM AS A 1030MB HIGH SETTLES OVER THE MID ATLANTIC WED AND THURS.
THE SFC HIGH WILL BRING MAINLY CLEAR SKIES...BUT KEEP TEMPS IN THE
MID/U 40S W/ A WEAK N/RLY SFC FLOW AND COOLER TEMPS RIDING DOWN INTO
THE REGION. THIS FLOW WILL ALSO BE THE FOCAL POINT FOR A POSSIBLE
WEAK IN-SITU DAMMING SCENARIO. ANY CAD SITU THAT DEVELOPS WOULD
LIKELY BE QUICKLY ERODED AS S/RLY FLOW INCR ON FRI AFTN. GFS SLIDES
THE SFC LOW ACROSS LAKE ERIE...W/ THE ECMWF FURTHER WEST ACROSS MI.
THE TRACK WILL HELP DETERMINE HOW STRONG THE PRE-FRONTAL S/RLY FLOW
WILL BE IN AND IF ANY FROZEN PRECIP WILL RESULT. THICKNESS SUPPORT A
RA/SN MIX FOR A BRIEF PERIOD EARLY FRI W/ THE ONSET...AND MAINLY
ACROSS THE WESTERN HALF OF THE CWA. RA PREDOMINANT ACROSS THE
COASTAL AND PIEDMONT REGIONS FRI MRNG/AFTN. HIGH PRESSURE OVER THE
EASTERN HALF OF THE U.S. FOR THE END OF THE WEEK...INTO EARLY NEXT
WEEK.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
EXPECT STRATO-CU TO DISSIPATE WITH DIURNAL MIXING AS CLOUDS
GRADUALLY MOVE TO THE NORTHEAST LATE THIS MORNING.
TWO SYSTEMS TO WATCH...MAINLY RAINMAKERS. TUES AFTN PRECIP WILL
BEGIN TO REACH THE I-95 TAF SITES...MAINLY LIGHT/INTERMTNT TILL TUES
NIGHT AHEAD OF THE COLD FRONT. S/RLY WINDS WILL INCR LATE TUES AND
GUST TO 20-30KT RANGE W/ THE FRONTAL PASSAGE EARLY WED. WINDS WILL
STAY IN THE 15-25KT RANGE THRU WED AS THE UPPER TROF PASSES. THURS
FAIRLY QUIET...AHEAD OF ANOTHER LOW PRESSURE SYSTEM ON FRI AND
EXITING THE REGION EARLY SAT. HIGH PRES FOR NEXT WEEKEND.
&&
.MARINE...
NORTHWEST WINDS BECOME LIGHT LATE THIS AFTERNOON AS THE SURFACE
RIDGE MOVES OVER THE WATERS.
SCA COND/S LATE TUES AND THRU MUCH OF WED. GUSTY WINDS WILL CHANNEL
ACROSS THE BAY LATE TUES...AHEAD OF STRONG COLD FRONT...EXPTD TO
MOVE ACROSS THE BAY EARLY WED. THE NEXT COLD FRONT EARLY SAT
MRNG...W/ MORE SCA COND/S POSSIBLE FRI INTO EARLY SAT.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ABW
NEAR TERM...ROGOWSKI
SHORT TERM...ABW
LONG TERM...GMS
AVIATION...ROGOWSKI/GMS
MARINE...ROGOWSKI/GMS
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1125 AM EST MON JAN 28 2008
.UPDATE...
FORECAST IS RATHER TRICKY FOR THIS AFTERNOON...PARTICULARLY WITH
REGARDS TO PCPN POTENTIAL.
15Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED GENERAL
UPPER LEVEL SW FLOW...BETWEEN A TROUGH OVER THE WESTERN U.S. AND A
RIDGE FROM THE SOUTHERN PLAINS INTO THE EASTERN GREAT LAKES. PLENTY
OF UPPER LEVEL MOISTURE STREAMING UP FROM THE EAST PACIFIC INTO THE
GREAT LAKES REGION AS SEEN ON WATER VAPOR...WHICH VISIBLE SATELLITE
IMAGERY AND SURFACE OBS INDICATES IS MOSTLY IN THE FORM OF HIGH
CLOUDS. BELOW THESE HIGH CLOUDS...12Z RAOB AND TAMDAR SOUNDINGS ARE
QUITE DRY...WITH 10-20C DEWPOINT DEPRESSIONS ACROSS THE REGION
BETWEEN 900-500MB. THE SOUNDINGS DEPICT A STRONG INVERSION BETWEEN
900-850MB THANKS TO 850MB TEMPS OF 3C AT APX...7C AT GRB AND 12C AT
MPX. NORMALLY THIS INVERSION WOULD MEAN TRAPPED LOW CLOUDS OVER THE
AREA. HOWEVER...VISIBLE IMAGERY AND MOST SURFACE OBS (EXCLUDING SAW)
SHOW VERY FEW IF ANY LOW CLOUDS ACROSS THE MIDWEST OR GREAT LAKES.
THIS APPEARS MOSTLY DUE TO THE LACK OF LOW LEVEL MOISTURE...THOUGH
DEWPOINTS ARE GENERALLY ON THE WAY UP NOW WITH MOST READINGS IN THE
25 TO 30 F RANGE. HIGHER DEWPOINTS...NEAR 40...ARE MOVING NORTHEAST
THROUGH KS INTO SW IA ON A STRONG LOW LEVEL JET. 850MB WINDS ARE SW
AT 60-65 KT AT PROFILERS ACROSS KS INTO NORTHERN MO. AT THE
SURFACE...A 987MB LOW IS SITUATED NEAR BISMARCK...WITH ALL OF THE
UPPER MISSISSIPPI VALLEY INTO THE GREAT LAKES IN THE WARM SECTOR.
GIVEN THE PRESENCE OF SO MUCH DRY AIR IN THE LOW AND MID LEVELS...AM
HIGHLY UNCERTAIN ON ANY PCPN OCCURRING TODAY. FOLLOWED THE DRIER
NAM/RUC SCENARIO OVER THE GFS AS THEY SEEM TO BE DOING BETTER WITH
RESPECT TO MOISTURE IN CURRENT TAMDAR SOUNDINGS. PLUS...
CLIMATOLOGICALLY SPEAKING THE WARM SECTOR OF A SYSTEM IN WINTER IS
NOT VERY FAVORABLE FOR PCPN BECAUSE MOISTURE IS HARDER TO COME BY.
THEREFORE MADE A SOMEWHAT DRASTIC CHANGE AND WENT COMPLETELY DRY FOR
TODAY. RAISED TEMPS SLIGHTLY GIVEN CURRENT READINGS ARE NEAR
PREVIOUS FORECAST HIGHS...BUT HIGH CLOUDS WHICH SHOULD INCREASE
THROUGH THE AFTERNOON WILL TEMPER READINGS FROM CLIMBING TOO HIGH.
AS FAR AS TONIGHT GOES...WANTED TO LOWER POPS ACROSS THE BOARD...BUT
THERE IS A BIT MORE DYNAMICAL FORCING TAKING PLACE. OVER THE WESTERN
U.P....MODELS INDICATE SOME MID-LEVEL FRONTOGENESIS AND POSSIBLE JET
COUPLING TAKING PLACE...WHICH COULD FORCE SATURATION AND PCPN. IN
THE FAR EASTERN U.P....ISENTROPIC LIFT MOVING UP THROUGH MISSOURI
INTO ILLINOIS (NOTED BY THICK MID-CLOUDS THERE) HEADS NORTHEAST AND
COULD PRODUCE SOME LIGHT PCPN. THE CENTRAL U.P. GETS STUCK
IN-BETWEEN PERHAPS INTO A DRIZZLE/FREEZING DRIZZLE. WILL SOMEWHAT
HEDGE THE GOING FORECAST TOWARDS THIS SCENARIO...WITH MORE CHANGES
FORTHCOMING ONCE THE 12Z GFS COMES IN TO SEE IF IT HANDLES THE
MOISTURE BETTER.
&&
.DISCUSSION...
THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE STORM POTENTIAL
FOR TUESDAY THROUGH WEDNESDAY.
WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER THE
PACIFIC NORTHWEST AND A FLATTEN RIDGE OVER GREAT LAKES REGION. A
CLOSED LOW IS JUST OFF THE COAST OF THE MID ATLANTIC STATES. WEAK
SHORTWAVES ARE OVER WESTERN ONTARIO...NORTH DAKOTA...AND WYOMING.
SURFACE ANALYSIS DEPICTS A LOW OVER NORTH DAKOTA WITH A WARM FRONT
LEADING IT STRETCHING INTO ILLINOIS. ANOTHER FRONTAL SYSTEM EXTENDS
FROM WINNIPEG EAST TO JAMES BAY. AN ELONGATED RIDGE STRETCHES FROM
GEORGIA NORTHEAST INTO SOUTHERN QUEBEC. THERE IS SOME FOG OVER THE
EASTERN OHIO RIVER VALLEY AND THE LOWER GREAT LAKES.
THE PACIFIC NORTHWEST LONGWAVE WILL SHIFT INTO THE NORTHERN HIGH
PLAINS TODAY. THE RIDGE OVER THE GREAT LAKES WILL SHIFT INTO THE
LOWER GREAT LAKES REGION AS THE LOW OFF THE ATLANTIC COAST WORKS
NORTHEAST. THE SHORTWAVE CLIMBING THE RIDGE WILL GENERALLY STAY
NORTH OF THE AREA TODAY...EXCEPT FOR THE SHORTWAVE OVER WYOMING
WHICH WILL RACE UP THE RIDGE INTO THE FORECAST AREA THIS AFTERNOON.
THE NOSE OF A 100+ KNOT UPPER LEVEL JET WILL SHIFT INTO WESTERN U.P.
BY LATE AFTERNOON. THE SURFACE LOW OVER MONTANA WILL CATCH UP WITH
THE LOW OVER NORTH DAKOTA AND MERGE AS THEY MOVE INTO WESTERN
MINNESOTA. THE ACCOMPANYING WARM FRONT WILL SHIFT INTO WISCONSIN.
THE LARGE RIDGE OVER THE EAST COAST APPEARS TO BE STEERING
EVERYTHING NORTHEAST. THE RIDGE KEEPS A SOUTHERLY FLOW THROUGHOUT
THE EASTERN CONUS DRAWING WARM AIR INTO THE GREAT LAKES REGION. THIS
SHOULD PUSH TEMPERATURES INTO THE MID AND UPPER 30S OVER THE U.P.
TODAY. THE INSTABILITY WITH THE SHORTWAVE...ISENTROPIC ASCENT AHEAD
OF THE FRONTAL SYSTEM...AND LOW LEVEL MOISTURE WILL GENERATE
PRECIPITATION. AN 850MB THERMAL TROUGH WILL SHIFT INTO THE AREA BY
LATE AFTERNOON ALONG WITH CLOUD COVER. THE FORECAST SOUNDING PROFILE
AND WARMER SURFACE TEMPERATURES SUGGEST THAT THERE WILL BE A MIX OF
RAIN AND SNOW. A 50KNOT LOW LEVEL JET WILL SWEEP ACROSS THE FORECAST
AREA TODAY. THE WARM SURFACE TEMPERATURES WILL HELP TO MIX SOME OF
THESE WINDS TO THE SURFACE.
MODELS IN PRETTY GOOD AGREEMENT WITH THE SYSTEM MOVING INTO THE
GREAT LAKES WITH THE NAM ONLY A LITTLE FARTHER NORTH THAN THE
CONSENSUS AND THE UKMET SLIGHTLY SLOWER. AS SUGGESTED BY HPC WILL GO
WITH THE GFS/ECMWF BLEND. THE LONGWAVE TROUGH WILL MOVE INTO THE
DAKOTA AND CENTRAL CANADA TONIGHT. SHORTWAVES EJECTED OUT AHEAD OF
THE TROUGH WILL SWEEP THROUGH THE AREA TONIGHT. THE SURFACE LOW WILL
MOVE OUT OF MINNESOTA AND INTO CENTRAL ONTARIO BY MIDNIGHT DRAGGING
THE COLD FRONT INTO THE WESTERN U.P. AND LAKE SUPERIOR. WINDS AT
THAT TIME WILL BEGIN TO VEER WEST AND NORTHWEST. ISENTROPIC ASCENT
AHEAD OF THE FRONT AND WARM MOISTURE AIR WILL CONTINUE TO FEED RAINS
OVER THE AREA. AS THE FRONT MOVES INTO THE AREA LATE TONIGHT...COLD
AIR WILL ADVECT IN AND CHANGE THE RAIN TO SNOW OVER THE WESTERN U.P.
THE TEMPERATURES WILL DROP RAPIDLY FOLLOWING THE FROPA. A SECONDARY
LOW DEVELOPING ALONG THIS FRONT WILL WORK NORTHWARD ALONG THE FRONT
AND REACH EASTERN IOWA BY SUNRISE.
THE LONGWAVE TROUGH WILL REACH MINNESOTA AND EASTERN MANITOBA BY
LATE TUESDAY AFTERNOON. WEAK SHORTWAVES AHEAD OF THE TROUGH WILL
SWEEP THROUGH THE FORECAST AREA. THE SURFACE LOW WILL LIFT INTO
NORTHEAST ONTARIO DRAGGING THE COLD FRONT INTO THE EASTERN U.P. THE
SURFACE LOW MOVING UP THE FRONT AND WILL REACH NORTHERN LOWER
MICHIGAN BY LATE TUESDAY. A -32C 850MB THERMAL WILL SHIFT INTO
MINNESOTA. LOW LEVEL MOISTURE AND INSTABILITY ALONG WITH THE COLD
AIR SPREADING ACROSS THE AREA WILL CHANGE THE PRECIPITATION TO SNOW
BY LATE MORNING. THE TIGHT GRADIENTS BEHIND THE FRONT WILL INCREASE
THE WINDS OVER THE WEST. THIS WILL PRODUCE SOME BLOWING SNOW BY LATE
AFTERNOON.
THE LONGWAVE TROUGH WILL MOVE OVER THE FORECAST AREA TUESDAY NIGHT.
THE SURFACE LOW WILL TRACK TO EAST CENTRAL ONTARIO DRAGGING THE COLD
FRONT THROUGH THE LOWER GREAT LAKES INTO THE MID ATLANTIC STATES.
THE CENTRAL PLAINS RIDGE WILL ADVANCE INTO THE MIDDLE MISSISSIPPI
RIVER VALLEY. THE 850MB THERMAL TROUGH WILL SHIFT INTO WESTERN LAKE
SUPERIOR. WINDS WILL BE MAINLY FROM THE WEST TO NORTHWEST ACROSS
LAKE SUPERIOR. A 40KNOT LOW LEVEL JET WILL SETTLE OVER THE FORECAST
AREA OVERNIGHT. THE COLD 850MB TEMPERATURES WILL PROMOTE MIXING SOME
OF THESE WINDS TO THE SURFACE. THE COLD TEMPERATURES AND WINDS WILL
GENERATE LAKE EFFECT SNOWS AND BLOWING SNOW MAINLY OVER THE WEST
END. A WINTER STORMS WATCH MAY BE WARRANTED. WIND CHILLS COULD REACH
ADVISORY CATEGORY LATE. SINCE IT COULD BE AN ADVISORY WILL HOLD OFF
ON ISSUING IT AT THIS TIME.
THE LONGWAVE TROUGH WILL SWING INTO NORTHERN ONTARIO AND SOUTHERN
QUEBEC ON WEDNESDAY. THE SURFACE LOW WILL LIKEWISE SWING INTO QUEBEC
WHILE THE RIDGE PUSHES DEEPER INTO THE UPPER MISSISSIPPI RIVER
VALLEY. ANTI-CYCLONIC FLOW WILL DRAW COLDER AIR INTO THE UPPER GREAT
LAKES REGION. DRY AIR WILL OVERSPREAD THE REGION AS WELL. THE
THERMAL TROUGH WILL SUPPORT LOW LEVEL INSTABILITY AND LAKE EFFECT
SNOWS. THE WINDS WILL MIX DOWN OVER LAKE SUPERIOR SO EXPECT TO SEE
MORE BLOWING SNOW. WITH THE TEMPERATURES AS COLD AS IT WILL
BE...EXPECT TO SEE FINER FLAKES WHICH WITH THE WINDS WILL REDUCE
VISIBILITY GREATLY. THE LONGER FETCH ACROSS THE CENTRAL AND EASTERN
PART OF LAKE SUPERIOR WILL CONTRIBUTE GREATLY TO SIGNIFICANT LES
OVER THE LUCE...ALGER AND EVEN NORTHERN SCHOOLCRAFT COUNTIES.
&&
.AVIATION (FOR THE 12Z TAF ISSUANCE)...
UPDATE FOR SAW...AMENDED THE TAF AS LOW CLOUDS HAVE COMPLETELY
DISSIPATED. 12Z SOUNDINGS AND AREA TAMDARS SHOW PLENTY OF DRY AIR
EVEN IN THE LOW LEVELS...WHICH COMBINED WITH THE STRONG SOUTHERLY
WIND HAS ALLOWED LOW CLOUDS TO SCATTER OUT. HAVE STILL FOLLOWED THE
IDEA OF LOW CLOUDS COMING IN...BUT NOT UNTIL 01Z. EVEN THIS MIGHT BE
A LITTLE TOO PESSIMISTIC. MORE DETAILS COMING WITH THE 18Z TAF
ISSUANCE.
PREVIOUS AVIATION DISCUSSION...
TRICKY FCST FOR SAW WITH SHALLOW INVRN AND SOME LO CLD/FOG UPSTREAM
TO THE S. TENDED ON THE PESSIMISTIC SIDE WITH LO CLD AS UPSLOPE SLY
FLOW THERE WL TEND TO MAINTAIN HI RH IN SHALLOW COLD WEDGE THAT
MIGHT HAVE DIFFICULTY MIXING OUT COMPLETELY. A LIGHT WINTRY MIX OF
PCPN IS LIKELY LATE TDAY/THIS EVNG AS SOMEWHAT HIER MSTR IS
STREAMING NEWD FM THE SRN PLAINS...BUT PCPN SHOULD BE ON THE LGT
SIDE WITH PERSISTENT DRY MID LVLS TRYING TO HANG ON. COOLING OF
LLVLS TNGT WL MAINTAIN MORE LO CLD/FOG AND PSBLY SOME FZDZ AT SAW.
THE FCST FOR CMX IS A BIT MORE STRAIGHT FORWARD AS UPSRTREAM AIRMASS
TO THE SSW IS WARMED/DRIED BY DOWNSLOPING OFF THE HIER TERRAIN.
SO... EXPECT VFR CONDITIONS TO PREDOMINATE THERE THRU THE DAY. APRCH
OF LO PRES TO THE NW OF LK SUP TNGT MAY RESULT IN A PD OF
RASN...WITH DETERIORATING CONDITIONS AS LLVLS BEGIN TO MOISTEN.
&&
.MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)...
EXPECT LO PRES DVLPG IN THE NORTHERN PLAINS THIS MRNG TO MOVE INTO
MN THIS EVENING AND THEN ONTARIO ON TUE MRNG WHILE DEEPENING. SLY
GALES HAVE DVLPD AS FCST OVER ECNTRL LK SUP...AND THESE WL CONTINUE
INTO TNGT BEFORE PRES GRADIENT GRDLY EASES LATE TNGT. A STRONG
ARCTIC COLD FRONT WILL CROSS LAKE SUPERIOR ON TUE AS THE LO MOVES TO
NEAR JAMES BAY IN THE EVNG. ANOTHER LO PRES SYS WILL DEVELOP ON THE
COLD FRONT OVER THE LOWER GREAT LAKES LATE ON TUE AND MOVE INTO SE
CAN AND INTENSIFY ON WEDNESDAY. GALE TO STORM FORCE W TO NW WINDS
AND HEAVY FRZG SPRAY WL DVLP IN THE WAKE OF THE COLD FNT AND THE
DVLPG LO ON THIS BNDRY AS ARCTIC AIR SURGES OVER LK SUP. PLAN ON THE
STRONGEST WINDS FM THE KEWEENAW AND ISLE ROYALE TO THE E. AS THE LO
CONTINUES NE ON THU...A HI PRES RDG WL BUILD TOWARD THE UPPER GREAT
LAKES. ON FRI...A DEVELOPING LO OVER THE TENNESSEE VALLEY IS
EXPECTED TO SHIFT NE TO THE EASTERN GREAT LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MICHIGAN...WINTER STORM WATCH FROM 1 PM TUESDAY TO 7 PM WEDNESDAY
FOR MIZ001>003.
MICHIGAN...WINTER STORM WATCH FROM 7 PM TUESDAY TO 7 PM WEDNESDAY
FOR MIZ006>007-085.
LAKE SUPERIOR...GALE WARNING UNTIL 4 AM EST TUESDAY FOR LSZ266-267.
LAKE MICHIGAN...GALE WARNING FROM 11 AM THIS MORNING TO 1 AM EST
TUESDAY FOR LMZ248-250.
&&
$$
UPDATE...AJ
DISCUSSION...DLG
AVIATION...KC/AJ
MARINE...KC
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
955 AM EST MON JAN 28 2008
.SYNOPSIS...
HIGH PRESSURE WILL BUILD INTO THE AREA TODAY BRINGING DRY
CONDITIONS AND MILD AIR. LOW PRESSURE OVER THE MIDWEST WILL PUSH
SLOWLY EAST AND PUSH LIGHT PRECIPITATION INTO THE AREA TUESDAY
AND EARLY WEDNESDAY. A COLD FRONT ON WEDNESDAY WILL BRING COLDER
AIR BACK INTO REGION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED AT 950 AM...SFC HI PRES RDG CNTRD OVER WRN NY WITH XTNSV
LOW CLD DECK OVER MUCH OF THE BGM CWA. SOME CLEARING ACRS FAR ERN
ZONES BUT CLDS HOLDING TUFF ALONG AND W OF I-81. ACARS DATA FROM
ASCENDING BGM FLIGHT THIS MRNG SHOWED NEARLY SATURATED CONDITIONS
TO JUST BLO 850 MB (SIMILAR TO 12Z BUF SNDG). WITH RDG AXIS OVERHEAD
AND LGT WINDS, THINK CLDS WILL HOLD FIRM OVER THE FINGER LAKES AND
CNTRL SRN TIER WELL INTO THE AFTN. CLDS MAY EVEN WORK BACK INTO
THE WRN MOHAWK VLY AND CATSKILLS THIS AFTN. HOWEVER, THINK OVERALL
TREND WIL BE FOR IMPVNG CONDITIONS AND WILL INDICATE PC SKIES BY
MID/LATE AFTN MOST AREAS, AS SUGGESTED BY LATEST RUC PROFILES.
PREV BLO...
LOPRES SPINS OVER THE WRN ATLANTIC WHILE A SHARP RDG BUILDS OVER
THE FCST AREA. AS USUAL...LGT NLY FLOW HAS RESULTED IN AN XTNSV SC
CVR OVRNGT EVEN WHILE CI DUMPS OVER THE TOP OF THE RDG. BACK EDGE
OF THE SC MAKING STEADY PROGRESS OVER WRN PA. LWR DEW PTS IN THE
CNTRL AND ERN ZONES MAY HELP ERODE THE CLDS SO WILL SIMPLY FCST
PTLY SUNNY SKIES FOR TODAY AS THE BACK EDGE WORKS EAST AND THE ERN
CLDS ERODE IN THE DRY AIR.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
LOPRES IS OVER NW MN 00Z TUE AS THE MODELS CONT THEIR TREND OF
TRACKING THE SYSTEM FURTHER WEST. UA LOW CLOSES OFF LTR TUE AS THE
SYSTEM GOES NEG. REALL NO FRCG MECHANISM FOR PCPN OVER THE FCST
AREA UNTIL THE COLD FNT PUSHES THRU 06Z TO 12Z WED. OPERATIONAL
GFS HAS BACKED OFF ON THE EARLY QPF AND IS MORE IN LINE WITH THE
NAM FOR ANY PREFNTL PCPN. STILL...BOTH THE GFS AND NAM DOP SOME
LGT PCPN OVER THE AREA BEGINNING EARLY TUE...AND IF IT
FALLS...TEMPS WILL BE COLD ENUF FOR SOME LGT FRZG PCPN. SO WHILE I
BELIEVE THE CHANCE IS SMALL...HAVE ELECTED TO KEEP CHANCE POPS IN
THE WEST FOR NOW.
SOME LGT PCPN IS PSBL DURING TUE DAYLIGHT HRS BUT ONCE AGAIN THERE
IS LTL TO FORCE THE PCPN. WILL STICK WITH CONTNUITY AND KEEP THE
LGT PCPN DURING TUE.
NEG TILT UA TROF ACCOMPANIES THE COLD FNT EARLY WED AND FINALLY
SOME LIFT FOR PCPN. DEEPER...FURTHER WEST LOW HAS DELAYED THE
PASSAGE OF THE COLD FNT AND ARRIVAL OF THE COLD AIR SO IN TURN HAS
DELAYED THE CHG OVER TO SNOW UNTIL LTR. VERY DRY AIR BHD THE FNT
WILL LIMT THE LES ACTIVITY BUT IT DOES LOOK AS THOUGH THE FLOW
WILL BE FVRBL FOR SOME LES OVER THE NRN ZONES...ESP LTR WED AS THE
COLD AIR BECOMES ESTABLISHED. GOOD GRADIENT AND PRESSURE RISES ON
WED WILL RESULT IN VERY WINDY CONDS BHD THE FNT.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
FOCUS THIS PERIOD CONTINUES TO BE ON CYCLONE MOVING OUT OF THE
PLAINS THROUGH THE OHIO VALLEY THURSDAY NIGHT. THIS SYSTEM WILL
SPREAD PRECIPITATION INTO OUR REGION AFTER MIDNIGHT, WITH
PRECIPITATION INTENSITY INCREASING ON FRIDAY.
CURRENT MODEL SOUNDINGS INDICATE THE PRECIPITATION WILL BE MAINLY
SNOW THURSDAY NIGHT, WITH SOME SLEET MIXING IN TOWARD MORNING...
PARTICULARLY OVER SOUTHERN HALF OF REGION. FRIDAY WILL SEE WARM
AIR CONTINUE TO SURGE NORTHWARD AHEAD OF COLD FRONT, CHANGING
PTYPE FOR SOUTHERN HALF OF FORECAST AREA TO RAIN. A MIX WILL HOLD
ON OVER THE NORTHEAST WHERE COLD AIR REMAINS ENTRENCHED.
ONCE THE COLD FRONT PULLS THROUGH DURING THE AFTERNOON, EXPECT THE
MAIN PTYPE TO GO BACK OVER TO SNOW. BIGGEST CONCERN WITH THIS
EVENT WILL BE MIXED PRECIP, AS THERE APPEARS TO BE ENOUGH WARM AIR
IN THE MODELS TO PRECLUDE STRONG SNOW GROWTH.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
LOW CLOUDS WILL BURN OFF AND RISE TO A SCATTERED 3000-5000 LAYER
BETWEEN 13Z AND 15Z. SKIES WILL FURTHER CLEAR THIS AFTERNOON AS
DRIER AIR MOVES OVER THE REGION.
EXPECT FAIRLY LIGHT WINDS TODAY, GENERALLY 5 TO 10 KTS BY LATE
MORNING.
SKIES WILL REMAIN MAINLY CLEAR UNTIL EARLY TUESDAY MORNING, WHEN A
LOW VFR DECK WILL THICKEN IN ADVANCE OF A WARM FRONT.
OUTLOOK...MVFR RESTRICTIONS LIKELY FROM TUES INTO TUES NGT WITH
CDFNT. GUSTY WINDS WILL PRECEDE AND FOLLOW THIS FNT. RAPID
CLEARING WITH VFR BY WED AFTN...PERSISTING THRU THURSDAY. SRN
STREAM SYSTEM APRCHS THU NGT WITH MVFR/IFR CONDITIONS INTO FRIDAY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DGM
NEAR TERM...
SHORT TERM...DGM
LONG TERM...DJP
AVIATION...DJP
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
455 AM CST MON JAN 28 2008
.SHORT TERM....TODAY THROUGH TUESDAY...PCPN TRENDS...EFFECTS OF
ARCTIC COLD FRONTAL PASSAGE AND WINTER WX HEADLINES ARE THE FOCUS
DURING THIS PERIOD.
HAVE PULLED POPS FROM THE MORNING FCST...AS MODELS CONTINUE TO
DELAY THE ONSET OF PCPN OVER C/NE WI...AND UPSTREAM OBS SHOW
MAINLY HIGH CLOUDS UPSTREAM. WILL KEEP LIKELY POPS FOR THIS
AFTERNOON...WITH FAIRLY LGT QPF. GIVEN THE LATER ARRIVAL TIME
AND EXPECTED HIGH TEMPS IN THE UPPER 30S TO LOWER 40S...WILL
JUST MENTION LIGHT RAIN ATTM.
TONIGHT...DEEPER SATURATION OCCURS DURING THE EVG HOURS...
COINCIDENT WITH THE ARRIVAL OF A S/W TROF AND SOME JET ENERGY.
DYNAMIC/EVAPORATIVE COOLING NEARLY WIPE OUT THE WARM LYR ALOFT
OVER NORTHERN WI DURING THE EARLY EVG...OPENING UP THE POSSIBILITY
OF A MIX OF RAIN/SNOW/SLEET. A DRY SLOT ARRIVE AFTER MIDNIGHT...
LIKELY RESULTING IN A DECREASE IN PCPN OVERNIGHT. HAVE REDUCED
POPS TO CHC CATEGORY...AND MENTIONED MAINLY LGT RAIN...DRIZZLE
AND AREAS OF FOG. THE LEADING EDGE OF THE ARTIC BOUNDARY MAY
SLIP INTO OUR NW COUNTIES OVERNIGHT...LEADING TO THE POSSIBILITY
OF SOME FZDZ IN NC/C WI.
ON TUES...THE POWERFUL ARCTIC FRONT IS EXPECTED TO SHIFT THROUGH
THE FA DURING THE 12-18Z PERIOD...WITH THE COLDEST AIR SURGING
INTO THE RGN DURING THE AFTERNOON. A MIX OF LIGHT RAIN OR
FREEZING RAIN WILL OCCUR DURING THE MORNING...FOLLOWED BY
SNOW DURING THE AFTERNOON AS DEEP FRONTOGENETIC FORCING AND
UPPER DIVG AHEAD OF A STG NEGATIVELY-TILTED S/W TROF ARRIVE.
EXPECT ACCUMS OF 1-3 INCHES OF POWDERY SNOW BY EVG. COMBO
OF STG CAA AND INCREASING ISALLOBARIC GRADIENT WILL CAUSE A
SIGNIFICANT INCREASE IN WEST WINDS DURING THE AFTERNOON...WITH
GUSTS TO 35-45 MPH CAUSING CONSIDERABLE BLOWING/DRIFTING SNOW.
TEMPS WILL FALL SHARPLY DURING THE AFTERNOON. GIVEN THE COMBINED
THREAT OF FREEZING PCPN...SOME MODEST SNOW ACCUMS...STG WINDS
AND ASSOC BLOWING SNOW AND FALLING TEMPS...HAVE OPTED TO ISSUE
A WINTER WEATHER ADVSY FOR THE ENTIRE CWA THROUGH TUES NGT.
.LONG TERM...TUESDAY NIGHT THROUGH NEXT SUNDAY
WINDY CONDITIONS ALONG WITH SNOW AND BLOWING SNOW WILL CREATE
HAZARDOUS CONDITIONS FOR AIRCRAFT OR BY CAR. PER COORDINATION
WITH SURROUNDING OFFICES AND WITH THE SHORT TERM FORECASTER...
MANY DIFFERENT HEADLINE OPTIONS WERE DISCUSSED DUE TO THE DIFFERENT
TYPES OF PRECIPITATION ON TUESDAY MORNING...THEN SNOW AND CONSIDERABLE
BLOWING AND DRIFTING SNOW AS THE ARCTIC COLD FRONT RACES ACROSS THE
AREA TUESDAY AFTERNOON AND TUESDAY EVENING. DECIDED TO GO WITH A
WINTER WEATHER ADVISORY FOR MUCH OF TUESDAY UNTIL 12Z WEDNESDAY.
FOR MY PART OF THE FORECAST...WILL BE DEALING WITH BAND OF SNOW
EXITING THE REGION ALONG WITH CONSIDERABLE BLOWING AND DRIFTING OF
THE SNOW. WIND GUSTS OVER 40 MPH WILL CREATE NEAR BLIZZARD
CONDITIONS AT TIMES. ALONG WITH THE WHITE OUT CONDITIONS...EXPECTING
AREA ROADS TO FREEZE UP DUE TO THE RAINFALL EARLY IN THE DAY AND
THEN SNOW AND BLOWING SNOW DURING THE AFTERNOON ALONG WITH
TEMPERATURES FALLING WELL BELOW FREEZING. THE EVENING COMMUTE ACROSS
NORTHEAST WISCONSIN COULD BE VERY TREACHEROUS DESPITE SANDING AND
SALTING OF AREA ROADS. THE SNOW SHOULD DIMINISH QUICKLY TO
SCATTERED FLURRIES TUESDAY EVENING. AREAS OF BLOWING SNOW SHOULD
CONTINUE OVERNIGHT. LATER TUESDAY NIGHT...WIND CHILL READINGS WILL
APPROACH WARNING CRITERIA...35 BELOW ZERO OR LOWER ACROSS CENTRAL
AND NORTH CENTRAL WISCONSIN. WIND CHILL ADVISORY CRITERIA SHOULD
BE MET OVER THE REMAINDER OF NORTHEAST WISCONSIN WITH WINDS OF 25
TO 35 BELOW ZERO. ALSO HAVE LOWER MINIMUM TEMPERATURES SEVERAL
DEGREES
ON WEDNESDAY...HAVE UNDERCUT GUIDANCE BY 5 DEGREES AND CUT AROUND
10 DEGREES OFF CURRENT HIGHS. DESPITE PARTLY CLOUDY CONDITIONS...
TEMPERATURES WILL STRUGGLE INTO THE SINGLE DIGITS ABOVE ZERO.
DO NOT PUT AWAY THE SNOW SHOVELS. AN ACTIVE PATTERN IS SETTING
UP LATER THIS WEEK...AND MODELS SUGGESTING A SIGNIFICANT SNOWFALL
BEYOND THE FORECAST PERIOD EARLY NEXT WEEK. RETURN FLOW SETS UP
WEDNESDAY NIGHT AND MODELS ARE STRUGGLING WITH LOW LEVEL
MOISTURE. HAVE INCREASED SNOW CHANCES OVER THE SOUTH WEDNESDAY
NIGHT INTO THURSDAY NIGHT. DEPENDING ON THE LOW LEVEL
MOISTURE...COULD BE SEVERAL INCHES OF SNOW DURING THIS PERIOD. A
SECONDARY STORM IS EXPECTED TO DEVELOP AND MOVE TOWARDS THE GREAT
LAKES REGION. THE 00Z ECMWF TONIGHT WOULD SUGGEST THAT A WINTER
STORM WATCH WILL NEEDED ACROSS NORTHEAST WISCONSIN AS THIS MODEL
TRACKS THE SYSTEM FURTHER WEST THAN THE CANADIAN/GFS. MY HUNCH IS
THAT THE GFS/CANADIAN WILL TREND FURTHER WEST ON LATER MODEL RUNS.
PLENTY OF TIME TO SORT THE DETAILS ON THIS FEATURE AND WILL BE
WATCHING IT CLOSELY OVER THE NEXT SEVERAL DAYS.
THE OTHER SIGNIFICANT STORM WILL OCCUR NEXT MONDAY INTO TUESDAY.
BOTH THE ECMWF AND GFS ARE CRANKING OUT 1.00 TO 2.00 INCHES OF
LIQUID QPF. IF THIS FALLS AS SNOW...THIS WOULD EQUATE TO 10 TO 20
INCHES OF SNOW. THE GFS IS FURTHER WEST AND WOULD SUGGEST SOME
RAIN OVER THE SOUTHEAST PORTION OF THE FORECAST AREA. ANOTHER
SYSTEM TO WATCH OVER THE NEXT WEEK. THE ECMWF WOULD SUGGEST ALL
SNOW.
&&
.AVIATION...ASIDE FROM SOME MVFR VSBYS IN LIGHT FOG THIS MORNING...
EXPECT VFR CONDITIONS TO PREVAIL UNTIL MID-LATE AFTERNOON...WHEN
LIGHT RAIN AND ASSOC MVFR CONDITIONS ARE EXPECTED TO DEVELOP.
EXPECT CIGS/VSBYS TO LOWER TONIGHT DUE TO RAINFALL AND INCREASING
DEW POINTS OVER A DEEP SNOWPACK. SOME FZDZ/LIGHT FZRA IS PSBL OVER
PARTS OF C/NC WI LATE TONIGHT. LLWS WILL CONTINUE TODAY INTO
TONIGHT...THEN DIMINISH OVERNIGHT AS WINDS ALOFT DECREASE.
&&
.MARINE...A GALE WARNING WILL BE IN EFFECT THROUGH TUESDAY NIGHT.
SOUTH GALES WILL DEVELOP THIS MORNING AND CONTINUE INTO TONIGHT.
WINDS WILL SUBSIDE A BIT DURING THE DAY ON TUESDAY...THEN
INCREASE TO GALE FORCE FROM THE WEST LATER TUESDAY INTO TUES NGT
AS AN ARCTIC FRONT MOVES THROUGH. WILL NEED TO MONITOR THE POTENTIAL
FOR A BRIEF PERIOD OF STORM FORCE GUSTS TUESDAY EVG AS STG CAA
AND THE CORE OF STRONGEST PRESSURE RISES MOVES THROUGH.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 12 PM TUESDAY TO 6 AM CST WEDNESDAY
FOR WIZ022-038>040-048>050-073-074.
WINTER WEATHER ADVISORY FROM 9 AM TUESDAY TO 6 AM CST WEDNESDAY
FOR WIZ005-010>013-018>021-030-031-035>037-045.
&&
$$
KIECKBUSCH/ECKBERG
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