AREA FORECAST DISCUSSION
NWS ALBANY NY
1229 PM EST SUN JAN 11 2009
.SYNOPSIS...
WEAK HIGH PRESSURE WILL BE OVER NEW YORK AND NEW ENGLAND THIS
AFTERNOON. A COLD FRONT AND ITS ASSOCIATED UPPER LEVEL DISTURBANCE
WILL MOVE THROUGH THE REGION OVERNIGHT AND EARLY MONDAY WITH A
CHANCE OF SNOW SHOWERS. HIGH PRESSURE WILL BRIEFLY BUILD BACK IN
FROM THE MID ATLANTIC REGION FOR MONDAY AFTERNOON AND EVENING.
&&
.NEAR TERM /THROUGH TONIGHT/...
THIS IS A SECOND UPDATE TO CANCEL THE REMAINING WARNINGS FOR THE
CAPITAL DISTRICT...NRN BERKSHIRES...SARATOGA REGION...AND SRN VT.
WE ALSO CANCELED THE ADVISORY FOR NRN WASHINGTON CO. SOME SCT
FLURRIES WILL LINGER IN THE WAKE OF THE DEPARTING LOW PRESSURE
SYSTEM EAST OF CAPE COD THIS MORNING. THE MSAS DATA SHOWS 3-4 HPA/3 HR
PRESSURE RISES OVER CNTRL NY/PA WITH A 1020 HPA HIGH BUILDING IN
FROM SOUTHEASTERN ONTARIO. THE VISIBLE SATELLITE PICTURE SHOWS THE
CLOUDS BREAKING UP WITH SOME CLEARING WITH THE SUBSIDENCE FROM THE
SFC HIGH. WE TRENDED THE SKY COVER TO PARTLY SUNNY CONDITIONS THIS
AFTERNOON. WE LOWERED MAX TEMPS A FEW DEGREES OVER THE MID HUDSON
VALLEY TO U20S TO NEAR 30.
IT SHOULD BE NOTED THE LOWER VISIBILITIES AT THE ALBANY
INTERNATIONAL AIRPORT ARE ASSOCIATED WITH DEICING AIRCRAFT AND
SNOW REMOVAL PER PHONE CALL TO AIRPORT OPERATIONS. THE
VISIBILITIES SHOULD COME SOON. SOME SCT FLURRIES HAVE BEEN
OCCURRING THERE...AND AT THE NWS/CESTM. PLEASE SEE OUR LATEST
PUBLIC INFORMATION STATEMENTS.
PREVIOUS DISCUSSION BELOW FROM 309 AM... AN UPPER LEVEL SHORT WAVE
TROF APPROACHING FROM THE GREAT LAKES WILL BE MOVING THROUGH LATE
TONIGHT INTO MON MORNING. WILL MENTION ISOLATED TO SCATTERED SNOW
SHOWERS THROUGH 12Z ASSOC WITH THE TROF PASSAGE. IN WAKE OF THE
TROF MON MORNING...SOME LAKE RESPONSE WILL BE POSSIBLE.
INSTABILITY CLASS ONLY CONDITIONAL...HOWEVER INVERSION HEIGHTS
WILL BE RISING TO AROUND 800 MB...WHICH WOULD CERTAINLY SUPPORT
SOME LAKE EFFECT SNOW SHOWER ACTIVITY. INITIALLY THE TRAJECTORY
FAVORS THE MOHAWK VALLEY MON MORNING...SHIFTING NORTH INTO THE
WESTERN ADIRONDACKS MON AFTERNOON. WILL MENTION LIKELY POPS FOR
THESE AREAS...BUT WITH LIGHT SNOWFALL AMOUNTS AROUND 1-2".
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
WEAK HIGH PRESSURE WILL CREST OVER THE REGION MONDAY NIGHT. WHILE
THE NIGHT STARTS WITH FEW CLOUDS...AND WITH FRESH SNOW...INCREASING
CLOUDS LATE AT NIGHT AS NEXT SYSTEM APPROACHES REGION WILL KEEP
TEMPS NEAR NORMS. TUESDAY CLIPPER TYPE SFC LOW DEEPENS IN THE
EASTERN GRTLKS AS SEVERAL 500HPA SHORT WAVES PHASE INTO A FULL
LATITUDE TROF FM HUDSON`S BAY TO THE GULF OF MEX. AS SFC LOW
DEEPENS ARCTIC AIR SURGES DOWN ON ITS WEST SIDE. WHILE THIS SFC
LOW TAKES A RATHER UNUSUAL TRACK FOR A CLIPPER...UP THE ST.
LAWRENCE VALLEY...THE AIRMASS AHEAD OF IT IS COLD...NO PTYPE
ISSUES....ALL SNOW. IT APPEARS TO TAP ENOUGH MOISTURE FOR A
PERIOD OF SNOW WITH A FEW INCHES...AS WELL AS SQUALLS WITH CFP
TUES EVENING. IN ITS WAKE TUES NIGHT MUCH COLDER AIR WILL POUR
INTO REGION. ALSO A VERY STRONG 500HPA SHORT WAVE WILL PIVOT
THROUGH THE REGION...ENHANCING THE SNOW...AND THE BURST OF LAKE
EFFECT IN THE CAA WITH THE ARCTIC SURGE. THIS SYSTEM EXITS THE
REGION LATE TUESDAY NIGHT...ANOTHER FAST MOVING SFC HIGH CRESTS
ACROSS THE REGION. WHILE COLD AIR MOVES INTO THE REGION
WEDNESDAY...THE MAIN CORE OF THE ARCTIC AIRMASS IS SITTING JUST
NORTH OF REGION OVER ONTARIO AND WESTERN QUEBEC. NEXT SHORT WAVE
AND ITS SFC CLIPPER LOW RACES EAST WEDNESDAY FROM THE WESTERN
GRTLKS...BRINGING ANOTHER PERIOD OF SNOW WED NIGHT THROUGH THURSDAY.
TEMPS CONTINUE TO SLIDE. BY WEDNESDAY WINDS AND TEMPS WILL RAISE
POTENTIAL TO REACH WIND CHILL CRITERIA.
GIVEN THE TIMING QUESTIONS RAISED BY HPC WITH THE NAM OF THESE TWO
SYSTEMS...FOR NOW THE FORECAST LEANS HEAVILY TWRD A GFS/GMOS
SOLUTION. GRIDS A BLEND OF CURRENT FCST...GMOS...MAV/MEX GUIDANCE.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
THE EFP FEATURES MORE OF THE SAME PARADE OF CLIPPER LOWS. THE
FIRST WED NIGHT INTO THU LOOKS THE MOST POTENT AT THIS POINT...AND
WILL BE FOLLOWED BY THE COLDEST AIRMASS OF THE WINTER. 1000-500DM
THICKNESS VALUES DROP BLO 500DM ACROSS THE REGION AND BLO 490 IN
THE NORTHERN TIER. TEMPS THU NIGHT WILL FALL WELL BLO ZERO F. BY
FRIDAY A MASSIVE CYCLONIC FLOW COVERS THE EASTERN HALF OF THE
NATION. THE MOST RECENT ARCTIC CORE IS LIFTING AWAY...AN ANOTHER
SHORT WAVE WITH A MORE SIGNIFICANT WAA COMPONENT WILL ENHANCE
CLOUDS...RAISE THE THREAT OF -SHSN...AND ENHANCE WHATEVER LAKE
EFFECT IS OCCURRING. FRIDAY NIGHT INTO SATURDAY YET ANOTHER CLIPPER
LOW RACES EAST TO OUR SOUTH. ITS A FRIGID TO VERY COLD PERIOD WITH
PERIODS OF -SHSN OR LIGHT SNOW. WE`RE IN THE DEEP NIGHT OF
WINTER...AND WE WILL KNOW IT.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
BEHIND THE WINTER STORM...VFR CONDITIONS WILL DOMINATE AS SCT
LINGERING CU/STRATOCU OF ABOUT 3-4 KFT WILL REMAIN ACROSS THE REGION
THIS AFTN DUE TO MOISTURE TRAPPED BENEATH THE DEVELOPING SUBSIDENCE
INVERSION AS A WEAK SURFACE HIGH PRESSURE AREA BUILDS INTO THE
REGION. A FAST MOVING WEAK UPPER LEVEL TROUGH WILL PUSH THROUGH THE
REGION DURING THE OVERNIGHT HOURS...BUT WITH LITTLE MOISTURE TO WORK
WITH...IT SHOULD PASS OVER TERMINALS TONIGHT WITH NOTHING MORE THAN
SOME PASSING MID LEVEL CLOUDS. GENERALLY MOSTLY CLEAR SKIES
/FEW-SCT LOW TO MID LEVEL CU/ WITH VFR CONDITIONS WILL CONTINUE ON
MONDAY. WINDS WILL REMAIN LIGHT THROUGH THE ENTIRE TAF PERIOD.
OUTLOOK....
MON PM...VFR. NO SIG WX.
TUE...VFR/MVFR...CHC -SHSN.
WED...VFR/MVFR...SLGT CHC -SHSN. WINDY.
THU...MVFR/IFR...CHC -SN.
&&
.HYDROLOGY...
NO HYDROLOGY RELATED PROBLEMS ARE EXPECTED THROUGH THE WEEKEND
INTO EARLY NEXT WEEK.
COLD WEATHER IS EXPECTED TO CONTINUE THROUGH ALL OF NEXT WEEK WITH
FRIGID WEATHER EXPECTED DURING THE LATER HALF OF THE WEEK. RIVER
ICE WILL THICKEN RAPIDLY IN SOME AREAS. RIVER STAGES/FLOWS MAY
START TO SHOW LARGE FLUCTUATIONS DUE TO ICE EFFECTS. THE
SNOWPACK...WHICH COVERS OUR ENTIRE AREA...IS EXPECTED TO INCREASE
IN WATER CONTENT. OUR INITIAL 08-09 WINTER SPRING FLOOD POTENTIAL
OUTLOOK WAS ISSUED FRIDAY MORNING. FOR DETAILS SEE ALBESFALY.
FOR DETAILS ON THE RIVERS...PLEASE VISIT THE ADVANCED HYDROLOGIC
PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...WASULA
NEAR TERM...JPV/WASULA
SHORT TERM...JPV
LONG TERM...SNYDER
AVIATION...FRUGIS
HYDROLOGY...11
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
622 AM CST SAT JAN 10 2009
.DISCUSSION...
348 AM CST
FOCUS REMAINS ON SHORT TERM WITH COMPLEX STORM SYSTEM STILL
MOVING ACROSS THE MIDWEST TODAY. GIVEN SLOWER TREND OF SYSTEM AND
PERSISTENT BANDING OF SNOW ACROSS AREA...AND POTENTIAL FOR 1-3 INCH
ADDITIONAL ACCUMULATIONS...HAVE ELECTED TO EXTEND EXISTING WINTER
WEATHER ADVISORY THROUGH 1 PM CST FOR AREAS ALONG/WEST OF INTERSTATE
39...AND THROUGH 6 PM CST FOR AREAS FARTHER EAST. IN ADDITION...HAVE
ALSO ELECTED TO ADD REMAINDER OF SOUTHERN CWA COUNTIES TO HEADLINES
AS WELL...DUE TO MIX OF FREEZING RAIN AND SLEET CURRENTLY MOVING
INTO THE PONTIAC/KANKAKEE.
EARLY MORNING REGIONAL RADAR MOSAIC DEPICTS NEARLY STATIONARY
WEST/EAST BANDING OF SNOW FROM IOWA INTO NORTHERN IL/EXTREME
SOUTHERN WI. ANALYSIS OF RUC DATA SUGGESTS THIS BANDED PRECIP HIGHLY
CORRELATED WITH FRONTOGENETIC FORCING IN 750-650 HPA LAYER. SHORT
TERM HIGH RESOLUTION GUIDANCE HAS DONE FAIRLY WELL IN SIMULATING
THIS NARROW AXIS OF FRONTOGENESIS LIFTING NORTH AND WEAKENING LAST
SEVERAL HOURS...THOUGH MODELS HAVE BEEN A BIT TOO FAR SOUTH WITH
QPF. RUC/NAM FORECAST TRENDS THROUGH THE MORNING SUGGEST BANDING
WILL CONTINUE...AND WILL GRADUALLY SHIFT SOUTH WITH TIME AND
EVENTUALLY BECOMING LESS FOCUSED. INDEED...CURRENT KLOT RADAR
REFLECTIVITY SUGGESTS THAT NEW AREA OF BANDING DEVELOPING FARTHER
SOUTH BETWEEN I-80/I-88 CORRIDORS FROM MENDOTA TOWARD SOUTHWEST
CHICAGO SUBURBS. BASED ON THESE RADAR/MODEL TRENDS EXPECT THAT
LIGHT/OCCASIONALLY MODERATE SNOW WILL CONTINUE ACROSS AREA THIS
MORNING WHILE GRADUALLY WEAKENING AND PULLING OFF TO THE SOUTHEAST
THIS AFTERNOON. HAVE GENERALLY FOLLOWED NAM QPF OR NAM/HPC BLEND
TODAY FOR PRECIP GRIDS TODAY...WITH 15:1 RATIO ROUGHLY YIELDING AN
ADDITIONAL 1-3 INCHES ACROSS ESPECIALLY CENTRAL CWA BEFORE SNOW ENDS
LATER TODAY.
BIGGER HEADACHES FOR THIS FORECASTER FARTHER SOUTH THIS MORNING...AS
AREA OF PRECIPITATION HAS DEVELOPED ACROSS CENTRAL ILLINOIS AHEAD OF
MISSOURI VORT MAX IN THE FORM OF FREEZING RAIN...SPREADING INTO
SOUTHEASTERN COUNTIES OF CWA. NO ACARS OR TAMDAR SOUNDINGS AVAILABLE
FROM CENTRAL IL THIS AM...THOUGH 00/06Z NAM BUFFER FORECAST
SOUNDINGS APPEAR UNDERDONE WITH +1/2 DEG WARM LAYER ALOFT GIVEN ILX
00Z RAOB +8 DEG C AT 850 HPA. WILL SEE FREEZING RAIN/SLEET TAPER TO
FREEZING DRIZZLE THIS MORNING AS VORT COMES ACROSS...THOUGH DO
EXPECT THAT COLUMN WILL EVENTUALLY COOL PER MODEL FORECASTS LATER
THIS MORNING WITH LIGHT SNOW THIS AFTERNOON ASSOCIATED DEFORMATION
PRECIP SHIELD. THUS ADVISORY SEEMS PRUDENT ACROSS SOUTHERN COUNTIES
FOR MIXED PRECIP CHANGING TO LIGHT SNOW THIS AFTERNOON...THOUGH
ACTUAL SNOW ACCUMS LIKELY ONLY 1-3 INCHES THERE.
A FEW SNOW SHOWERS MAY LINGER EARLY THIS EVENING ACROSS NORTHWEST
INDIANA AS WINDS BECOME NORTHERLY AND COLDER AIR IS PULLED INTO BACK
SIDE OF DEEPENING LOW OFF TO OUR SOUTHEAST. FORECAST SOUNDINGS OVER
SOUTH END OF LAKE SHOW MARGINAL DELTA/T AND INVERSION HEIGHTS
QUICKLY LOWERING BELOW 4 KFT WHICH SUGGESTS LITTLE ORGANIZATION AND
SHORT DURATION AND EXPECT PERHAPS ONLY A DUSTING IF THAT FROM ANY
LES CONTRIBUTION BEFORE PRECIP MOVES EAST OF CWA.
VERY LITTLE IN WAY OF CHANGES TO MEDIUM/LONG RANGE PORTIONS OF
FORECAST DUE TO SHORT TERM FOCUS. DID BOOST CHANCE POPS A BIT WITH
CLIPPER SYSTEM WHICH ZIPS SOUTHEAST ACROSS AREA SUNDAY. LESS THAN AN
INCH ACCUMULATION EXPECTED AND THAT MAINLY ACROSS NORTHEAST 1/2 OF
CWA. ALSO BOOSTED POPS MONDAY WITH GUIDANCE IN GOOD AGREEMENT IN
DIGGING YET ANOTHER CLIPPER ALONG LOW LEVEL BAROCLINIC BOUNDARY
WHICH REPRESENTS SOUTHERN PERIPHERY OF ARCTIC AIR ACROSS NORTHERN
NOAM. NO CHANGES MADE TO TEMPS IN LATER PERIODS AS STILL APPEARS
MIDWEST WILL GET REAL TASTE OF THE ARCTIC MID/LATE WEEK AS GFS/ECMWF
CONTINUE TO PULL -20 C 850 AIR ACROSS THE REGION OVER OUR NEW SNOW
COVER.
RATZER
&&
.AVIATION...
620 AM CST
1200 UTC TAFS...MAIN AVIATION CONCERNS WILL CONTINUE TO CENTER ON
SNOW AND REDUCED CIGS/VSBYS ALONG WITH GUSTY NORTH NORTHEAST
WINDS.
LIGHT SNOW CONTINUED ACROSS MOST OF NORTHERN ILLINOIS AND
NORTHWEST INDIANA EARLY THIS MORNING. EARLIER IN THE NIGHT...MORE
INTENSE BANDING WAS NOTED ON RADAR IMAGERY ACROSS FAR NORTHERN
ILLINOIS TOWARD THE WISCONSIN STATELINE...BUT THIS BAND HAS
RAPIDLY DETERIORATED. THREAT OF ACCUMULATING SNOW WILL CONTINUE
INTO THE EARLY AFTERNOON HOURS HOWEVER AS MAIN MID/UPPER LEVEL
TROUGH IS STILL WELL OFF TO THE WEST FROM WESTERN IOWA THROUGH
EASTERN KANSAS. AS THIS WAVE APPROACHES TODAY...EXPECTING MID
LEVEL FRONTOGENESIS TO BECOME ENHANCED ONCE AGAIN AND MAY FORM A
BIT MORE ORGANIZED OF A SNOW BAND LATE THIS MORNING/EARLY THIS
AFTERNOON. IF THIS DOES OCCUR...EXPECTING MDW/GYY TO BE MORE
IMPACTED THAN OTHER TERMINALS GIVEN EXPECTED PLACEMENT OF THE MID
LEVEL FRONT BY THIS TIME. THUS...HAVE CARRIED IFR CIGS/VSBYS INTO
THE EARLY AFTERNOON AT THESE TERMINALS. FOR THIS MORNING WILL
MAINTAIN IDEA OF LIFR VSBYS/IFR CIGS ACROSS ALL TERMINALS EXCEPT
ROCKFORD WHERE SNOW IS EXPECTED TO BE LIGHTER WITH IFR VSBYS
THROUGH LATE MORNING...FOLLOWED BY IMPROVING CONDITIONS THIS
AFTERNOON. SNOW SHOULD BE DIMINISHING AT EVEN GYY/MDW BY LATE
AFTERNOON AS THE STRONGEST MID/UPPER LEVEL FORCING SHIFTS EAST OF
THE AREA.
NORTHEAST WINDS GUSTING TO 20 KNOTS THIS MORNING WILL BECOME NORTH
THIS AFTERNOON AS THE SURFACE LOW ACROSS SOUTHERN ILLINOIS MOVES
ACROSS KENTUCKY THIS AFTERNOON. WINDS WILL SUBSIDE THIS EVENING AS
A SFC RIDGE AXIS MOVES INTO THE MID MS RIVER VALLEY. EXPECTING
SOME LINGERING MVFR CIGS IN THE EVENING...FOLLOWED BY VFR
CONDITIONS THROUGH THE REMAINDER OF THE NIGHT WITH JUST SOME
INCREASING HIGH CLOUDINESS IN ADVANCE OF NEXT FAST MOVING SYSTEM.
MARSILI
&&
.MARINE...
312 AM CST
MAIN MARINE FORECAST CONCERNS WILL BE GUSTY NORTHEAST WINDS
TODAY...AND THEN POTENTIAL FOR GALES MONDAY NIGHT INTO EARLY
TUESDAY. SURFACE LOW PRESSURE MOVING ACROSS SOUTHERN ILLINOIS THIS
MORNING...WILL TRACK ACROSS NORTHERN KENTUCKY THIS AFTERNOON.
NORTHEAST WINDS WILL BACK TO THE NORTH IN RESPONSE TO THE EASTWARD
PROGRESSION OF THIS LOW WITH SPEEDS DIMINISHING LATER THIS AFTERNOON
AND ESPECIALLY THIS EVENING AS A RIDGE OF HIGH PRESSURE APPROACHES
SOUTHERN LAKE MICHIGAN. A FEW GUSTS TO 25 KNOTS POSSIBLE THIS
MORNING BUT WITH FAIRLY SUBSTANTIAL ICE COVER ACROSS NEARSHORE
WATERS WILL CONTINUE TO HOLD OFF ON ANY NEARSHORE HEADLINES WITH
ONLY MARGINAL WIND SPEEDS EXPECTED FOR ADVISORY CRITERIA.
THE RIDGE AXIS MOVING ACROSS SOUTHERN LAKE MICHIGAN TONIGHT WILL
RAPIDLY TRACK OFF TO THE EAST ON SUNDAY AND ATTENTION WILL THEN TURN
TO DEVELOPING LOW PRESSURE ACROSS THE NORTHERN PLAINS SUNDAY NIGHT
INTO EARLY MONDAY. THIS LOW IS EXPECTED TO MOVE ACROSS LAKE MICHIGAN
EARLY MONDAY EVENING WITH MUCH COLDER AIR FILTERING INTO THE WESTERN
GREAT LAKES REGION FOR TUESDAY. WILL INCLUDE MENTION OF GALES MONDAY
EVENING THROUGH TUESDAY MORNING AND BASED ON ARCTIC AIR MASS MOVING
IN...WILL ALSO MENTION POTENTIAL OF FREEZING SPRAY DURING THIS TIME
PERIOD. WINDS WILL THEN SHARPLY DIMINISH TUESDAY EVENING AS ANOTHER
RIDGE OF HIGH PRESSURE BUILDS INTO THE REGION.
MARSILI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-
ILZ019 UNTIL 1 PM SATURDAY.
WINTER WEATHER ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-
ILZ020-ILZ021-ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 6 PM
SATURDAY.
IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
UNTIL 6 PM SATURDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 6 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
348 AM CST SAT JAN 10 2009
.DISCUSSION...
348 AM CST
FOCUS REMAINS ON SHORT TERM WITH COMPLEX STORM SYSTEM STILL
MOVING ACROSS THE MIDWEST TODAY. GIVEN SLOWER TREND OF SYSTEM AND
PERSISTENT BANDING OF SNOW ACROSS AREA...AND POTENTIAL FOR 1-3 INCH
ADDITIONAL ACCUMULATIONS...HAVE ELECTED TO EXTEND EXISTING WINTER
WEATHER ADVISORY THROUGH 1 PM CST FOR AREAS ALONG/WEST OF INTERSTATE
39...AND THROUGH 6 PM CST FOR AREAS FARTHER EAST. IN ADDITION...HAVE
ALSO ELECTED TO ADD REMAINDER OF SOUTHERN CWA COUNTIES TO HEADLINES
AS WELL...DUE TO MIX OF FREEZING RAIN AND SLEET CURRENTLY MOVING
INTO THE PONTIAC/KANKAKEE.
EARLY MORNING REGIONAL RADAR MOSAIC DEPICTS NEARLY STATIONARY
WEST/EAST BANDING OF SNOW FROM IOWA INTO NORTHERN IL/EXTREME
SOUTHERN WI. ANALYSIS OF RUC DATA SUGGESTS THIS BANDED PRECIP HIGHLY
CORRELATED WITH FRONTOGENETIC FORCING IN 750-650 HPA LAYER. SHORT
TERM HIGH RESOLUTION GUIDANCE HAS DONE FAIRLY WELL IN SIMULATING
THIS NARROW AXIS OF FRONTOGENESIS LIFTING NORTH AND WEAKENING LAST
SEVERAL HOURS...THOUGH MODELS HAVE BEEN A BIT TOO FAR SOUTH WITH
QPF. RUC/NAM FORECAST TRENDS THROUGH THE MORNING SUGGEST BANDING
WILL CONTINUE...AND WILL GRADUALLY SHIFT SOUTH WITH TIME AND
EVENTUALLY BECOMING LESS FOCUSED. INDEED...CURRENT KLOT RADAR
REFLECTIVITY SUGGESTS THAT NEW AREA OF BANDING DEVELOPING FARTHER
SOUTH BETWEEN I-80/I-88 CORRIDORS FROM MENDOTA TOWARD SOUTHWEST
CHICAGO SUBURBS. BASED ON THESE RADAR/MODEL TRENDS EXPECT THAT
LIGHT/OCCASIONALLY MODERATE SNOW WILL CONTINUE ACROSS AREA THIS
MORNING WHILE GRADUALLY WEAKENING AND PULLING OFF TO THE SOUTHEAST
THIS AFTERNOON. HAVE GENERALLY FOLLOWED NAM QPF OR NAM/HPC BLEND
TODAY FOR PRECIP GRIDS TODAY...WITH 15:1 RATIO ROUGHLY YIELDING AN
ADDITIONAL 1-3 INCHES ACROSS ESPECIALLY CENTRAL CWA BEFORE SNOW ENDS
LATER TODAY.
BIGGER HEADACHES FOR THIS FORECASTER FARTHER SOUTH THIS MORNING...AS
AREA OF PRECIPITATION HAS DEVELOPED ACROSS CENTRAL ILLINOIS AHEAD OF
MISSOURI VORT MAX IN THE FORM OF FREEZING RAIN...SPREADING INTO
SOUTHEASTERN COUNTIES OF CWA. NO ACARS OR TAMDAR SOUNDINGS AVAILABLE
FROM CENTRAL IL THIS AM...THOUGH 00/06Z NAM BUFFER FORECAST
SOUNDINGS APPEAR UNDERDONE WITH +1/2 DEG WARM LAYER ALOFT GIVEN ILX
00Z RAOB +8 DEG C AT 850 HPA. WILL SEE FREEZING RAIN/SLEET TAPER TO
FREEZING DRIZZLE THIS MORNING AS VORT COMES ACROSS...THOUGH DO
EXPECT THAT COLUMN WILL EVENTUALLY COOL PER MODEL FORECASTS LATER
THIS MORNING WITH LIGHT SNOW THIS AFTERNOON ASSOCIATED DEFORMATION
PRECIP SHIELD. THUS ADVISORY SEEMS PRUDENT ACROSS SOUTHERN COUNTIES
FOR MIXED PRECIP CHANGING TO LIGHT SNOW THIS AFTERNOON...THOUGH
ACTUAL SNOW ACCUMS LIKELY ONLY 1-3 INCHES THERE.
A FEW SNOW SHOWERS MAY LINGER EARLY THIS EVENING ACROSS NORTHWEST
INDIANA AS WINDS BECOME NORTHERLY AND COLDER AIR IS PULLED INTO BACK
SIDE OF DEEPENING LOW OFF TO OUR SOUTHEAST. FORECAST SOUNDINGS OVER
SOUTH END OF LAKE SHOW MARGINAL DELTA/T AND INVERSION HEIGHTS
QUICKLY LOWERING BELOW 4 KFT WHICH SUGGESTS LITTLE ORGANIZATION AND
SHORT DURATION AND EXPECT PERHAPS ONLY A DUSTING IF THAT FROM ANY
LES CONTRIBUTION BEFORE PRECIP MOVES EAST OF CWA.
VERY LITTLE IN WAY OF CHANGES TO MEDIUM/LONG RANGE PORTIONS OF
FORECAST DUE TO SHORT TERM FOCUS. DID BOOST CHANCE POPS A BIT WITH
CLIPPER SYSTEM WHICH ZIPS SOUTHEAST ACROSS AREA SUNDAY. LESS THAN AN
INCH ACCUMULATION EXPECTED AND THAT MAINLY ACROSS NORTHEAST 1/2 OF
CWA. ALSO BOOSTED POPS MONDAY WITH GUIDANCE IN GOOD AGREEMENT IN
DIGGING YET ANOTHER CLIPPER ALONG LOW LEVEL BAROCLINIC BOUNDARY
WHICH REPRESENTS SOUTHERN PERIPHERY OF ARCTIC AIR ACROSS NORTHERN
NOAM. NO CHANGES MADE TO TEMPS IN LATER PERIODS AS STILL APPEARS
MIDWEST WILL GET REAL TASTE OF THE ARCTIC MID/LATE WEEK AS GFS/ECMWF
CONTINUE TO PULL -20 C 850 AIR ACROSS THE REGION OVER OUR NEW SNOW
COVER.
RATZER
&&
.AVIATION...
0600 UTC TAFS...MAIN CONCERN FOR THE OVERNIGHT AND MORNING HOURS
WILL CONTINUE TO FOCUS ON THE ONGOING WINTER WEATHER SITUATION.
AN NARROW SWATH OF SNOW EXTENDS FROM SOUTHERN IOWA...THROUGH NORTHERN
ILLINOIS/INDIANA TO NORTHERN OHIO. THE SWATH OF SNOW HAS BECOME NEARLY
STATIONARY...SO HAVE EXTENDED THE PERIOD OF IFR/LIFR CIGS/VIS
THROUGH THE LATE MORNING HOURS. LATEST MODEL GUIDANCE IS ALSO
SUGGESTING THAT MVFR CIGS WILL HANG IN LONGER THAN PREVIOUSLY
ANTICIPATED...SO HAVE EXTENDED MVFR CIGS THROUGH THE LATE
AFTERNOON AND EARLY EVENING HOURS. ALSO...WITH THE SLOW
PROGRESSION OF THE PATTERN...THE TERMINALS WILL LIKELY SEE A
LONGER PERIOD OF LIGHT SNOW INTO THE LATE AFTERNOON. FINALLY
EXPECT TO SEE SOME LARGE SCALE SUBSIDENCE AND DRYING BY EARLY
EVENING AND HAVE REDUCED CLOUD COVER TO JUST SCT CI. VFR
CONDITIONS WILL THEN PERSIST THROUGH THE REMAINDER OF THE EVENING
AND OVERNIGHT TOMORROW.
KREIN
&&
.MARINE...
312 AM CST
MAIN MARINE FORECAST CONCERNS WILL BE GUSTY NORTHEAST WINDS
TODAY...AND THEN POTENTIAL FOR GALES MONDAY NIGHT INTO EARLY
TUESDAY. SURFACE LOW PRESSURE MOVING ACROSS SOUTHERN ILLINOIS THIS
MORNING...WILL TRACK ACROSS NORTHERN KENTUCKY THIS AFTERNOON.
NORTHEAST WINDS WILL BACK TO THE NORTH IN RESPONSE TO THE EASTWARD
PROGRESSION OF THIS LOW WITH SPEEDS DIMINISHING LATER THIS AFTERNOON
AND ESPECIALLY THIS EVENING AS A RIDGE OF HIGH PRESSURE APPROACHES
SOUTHERN LAKE MICHIGAN. A FEW GUSTS TO 25 KNOTS POSSIBLE THIS
MORNING BUT WITH FAIRLY SUBSTANTIAL ICE COVER ACROSS NEARSHORE
WATERS WILL CONTINUE TO HOLD OFF ON ANY NEARSHORE HEADLINES WITH
ONLY MARGINAL WIND SPEEDS EXPECTED FOR ADVISORY CRITERIA.
THE RIDGE AXIS MOVING ACROSS SOUTHERN LAKE MICHIGAN TONIGHT WILL
RAPIDLY TRACK OFF TO THE EAST ON SUNDAY AND ATTENTION WILL THEN TURN
TO DEVELOPING LOW PRESSURE ACROSS THE NORTHERN PLAINS SUNDAY NIGHT
INTO EARLY MONDAY. THIS LOW IS EXPECTED TO MOVE ACROSS LAKE MICHIGAN
EARLY MONDAY EVENING WITH MUCH COLDER AIR FILTERING INTO THE WESTERN
GREAT LAKES REGION FOR TUESDAY. WILL INCLUDE MENTION OF GALES MONDAY
EVENING THROUGH TUESDAY MORNING AND BASED ON ARCTIC AIR MASS MOVING
IN...WILL ALSO MENTION POTENTIAL OF FREEZING SPRAY DURING THIS TIME
PERIOD. WINDS WILL THEN SHARPLY DIMINISH TUESDAY EVENING AS ANOTHER
RIDGE OF HIGH PRESSURE BUILDS INTO THE REGION.
MARSILI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-
ILZ019 UNTIL 1 PM SATURDAY.
WINTER WEATHER ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-
ILZ020-ILZ021-ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 6 PM
SATURDAY.
IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
UNTIL 6 PM SATURDAY.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
859 AM EST SAT JAN 10 2009
.UPDATE...
QUICK UPDATE OUT TO ADD IN MENTION OF FREEZING RAIN IN SE THIRD OF
CWA. TONGUE OF WARM AIR SEEN ON TAMDAR SOUNDINGS AND THIS POCKET
OF WARM AIR IS BEING SEEN IN TERMS OF FREEZING RAIN BEING REPORTED
FROM GRISSOM UP TO FT WAYNE AND NE FROM THERE. HAVE AMENDED THE
GRIDS TO SIMPLY ADD THE MENTION BUT KEEPING ICE ACCUMULATIONS ON
THE LIGHT SIDE AT THIS POINT. WILL CONTINUE TO MONITOR SNOWFALL TO
THE WEST IN WHAT LOOKS LIKE AN EXPANDING DEFORMATION ZONE THAT
WILL LIKELY GIVE MUCH OF THE CWA A QUICK BURST OF MODERATE TO
LOCALLY HEAVY SNOW LATER THIS MORNING INTO THIS AFTERNOON.
REMAINDER OF THE GRIDS LOOK GOOD FOR NOW SO WILL MONITOR TRENDS
OVER THE NEXT COUPLE OF HOURS AND SEE HOW THINGS UNFOLD.
&&
.PREV DISCUSSION... /ISSUED 740 AM EST SAT JAN 10 2009/
AVIATION...
LL MSTR SURGE RESULTING IN EXPANDING AREA OF INTENSE SNOWFALL ACRS
MUCH OF NRN IN THIS AM YET LARGELY MISSING KFWA ATTM. XPC MOD SNOW
AND IFR CONDS TO CONT AT KSBN THROUGH AT LEAST 17Z IF NOT LONGER
GIVEN TRAILING ELONGATED DEFORMATION ZONE EXTENDING ALL THE WAY BACK
INTO CNTRL IA AHD OF INTENSE SW TROUGH OVR SE NE. AT KFWA...BROKEN
SHALLOW CONV DVLPMNT STILL SEEN WWD TO KBMI AND TEMPO GROUP THERE
THIS MORNING WILL STILL FIT W/BURSTS OF HEAVIER SNOWFALL AND CONTD
IFR. OTHERWISE 06Z FCST CLOSE AND LARGELY LEFT INTACT THROUGH THE PD.
SHORT TERM...THROUGH SUN NIGHT
INTENSE SW TROUGH NOTED PER VAPOR ACRS THE NE SANDHILLS THIS
MORNING. DOWNSTREAM HGT FALLS AND INTENSE LL MSTR SURGE TAKING PLACE
NEWD INTO THE OH/MS VALLEYS W/CONVN STILL NOTED AT THIS HOUR FM NW
AR INTO SE MO. MEANWHILE W-E DEFORMATION SNOW ZONE HAS SHIFTED A BIT
NORTH FM EVENING AND WAS CNTRD ALG THE IN/MI BORDER WHILE MIXED PCPN
IN SHALLOW CONVN CONTD TO EXPAND FM CNTRL IL EWD THROUGH CNTRL/SRN
IN.
NR TERM FCST DIFFICULT TO SAY THE LEAST. FURTHER MSTR ENTRAINMENT
DOWNSTREAM OF DEEPENING MID LVL TROUGH AND OBSVD SAT/RADAR TRENDS
SUGGEST GFS/EC SOLUTIONS IDEAL SHRT TERM. ITS HANDLING OF SECONDARY
DEFORMATION DVLPMNT UNDERNEATH COUPLING JET STREAKS LTR THIS MORNING
LOOKS IDEAL AND FURTHER VERIFIED W/EXPANDING INTENSE PCPN OVR CNTRL
IL. WARM NOSE PUSH ALREADY SEEN IN FAR SRN CWA W/IP/ZR IN HUNTINGTON
REPORTED EARLIER AND WILL SEE ADDNL ICE FAR SOUTH AS CNTRL IL AREA
EXPANDS E/NE. PROBS LIE W/SERN EXTEND OF CURRENT WARNING...FORT
WAYNE TO DEFIANCE AND SOUTHWARD AND OBVIOUSLY LESS SNOW TO FALL
THERE YET COUNTERED BY POTENTIAL FOR SOME ICING THROUGH LATE MORNING
AND BEST COURSE OF ACTION KEEP W/EXISTING HEADLINES THERE EVEN
THROUGH SNOW AMTS WILL FALL WELL SHORT. FARTHER NORTH...SVRL HR PD
OF HEAVY SNOWFALL FM MID MORNING INTO EARLY AFTN QUITE LIKELY NW OF
A LOGANSPORT TO TOLEDO LINE AND ADDED MENTION TO GRIDS. THIS SHLD
PUSH MUCH OF WARNING AREA WELL INTO 6-10 INCH RANGE GIVEN PRIOR 2-5
INCHES FM YDA...AND XPC NE CORNER WILL EXCEED A FOOT IN SPOTS. IN
ADDN...SOME POTENTIAL THIS MAY LINGER FURTHER INTO LT AFTN/EARLY EVE
ESP EAST W/4KM MODEL OUTPUT EVEN SLOWER TO PUSH INTENSE SYS OUT AND
IT SEEMS SLIGHT EXTENSION IN ENDING TIME OF HEADLINES WARRANTED.
BRIEF PD OF WRAP AROUND SHSN AUGMENTED W/MARGINAL LK CONTRIBUTION
BUT FLW BACKS RAPIDLY AHD OF SECONDARY SW ALREADY BREAKING OVR WRN
RIDGE THROUGH BC THIS MORNING. MAY INDEED SEE A FEW FLURRIES AS
EARLY AS SUN AFTN BUT MORE LIKELY SUN NIGHT AND CURRENTLY
MENTIONED.
LONG TERM...
MONDAY THROUGH FRIDAY....THIS PERIOD WILL BE VERY ACTIVE WITH
CONDITIONS BECOMING BITTERLY COLD LATE. TWO CLIPPER TYPE SYSTEMS
WILL MOVE ACROSS THE AREA...EACH ACCOMPANIED BY AN ARCTIC FRONT.
OVERALL...THE GFS...GFS ENSEMBLES...ECMWF OPERATION RUN AND THE
CANADIAN ENSEMBLES ARE IN REASONABLE AGREEMENT WITH THE TIMING OF
THESE TWO SYSTEMS. THE FIRST ONE SHOULD REACH THE AREA MONDAY
NIGHT...AND THE SECOND ONE ABOUT WEDNESDAY. THE GFS MEAN ENSEMBLE
MOS HAS BEEN TRENDING WEDNESDAY AND THURSDAY TEMPS COLDER...BUT
FORECAST HIGHS AND LOWS STILL LOOK TOO WARM BASED ON UPSTREAM
TEMPERATURES. THE 10/00Z MEX MOS ALSO LOOKS TOO WARM WITH A
CLIMATE BIAS IN DAYS 6 AND 7. GIVEN UPSTREAM BITTERLY COLD
TEMPERATURES...FROM THE ALASKAN INTERIOR INTO THE YUKON
TERRITORY UP TO -60F...HAVE CONTINUED TO TREND TEMPERATURES DOWN.
GFS FORECAST SFC HIGH PRESSURES OF 1050 TO 1060 MB THE LAST
SEVERAL RUNS INDICATIVE OF THE STRENGTH OF THE COLD AIR. FOR THIS
PACKAGE...REORGANIZED THE GRIDS SOME INCLUDING SNOW CHANCES TO
ACCOMMODATE LATEST THINKING ON THE ARRIVAL AND PASSING OF THE 2
CLIPPER TYPE SYSTEMS. THERE ARE LIKELY TO BE A NUMBER OF WINTER
WEATHER HIGHLIGHTS EVENTUALLY NEEDED THE COMING WEEK GIVEN
FAVORABLE SNOWFALL POTENTIAL WITH WINDY CONDITIONS AND BITTERLY
COLD TEMPERATURES.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR INZ018.
WINTER STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR
INZ006>009-016-017.
WINTER STORM WARNING UNTIL 4 PM EST /3 PM CST/ THIS AFTERNOON
FOR INZ003>005-012-014.
WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR INZ013-
015-020-022-023.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR
INZ024>027-032>034.
MI...WINTER STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR MIZ080-
081.
WINTER STORM WARNING UNTIL 4 PM EST THIS AFTERNOON FOR
MIZ077>079.
OH...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR OHZ002-004-
005-015-016-024-025.
WINTER STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR OHZ001.
LM...NONE.
&&
$$
SHORT TERM...HOLSTEN
LONG TERM...SKIPPER
AVIATION...HOLSTEN
UPDATE...FISHER
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
600 AM EST SAT JAN 10 2009
.AVIATION...DISCUSSION FOR THE 12Z TAFS
FREEZING PRECIP WILL REMAIN A THREAT FOR LAF WITH ALL OTHER TAF
SITES EXPECTED TO STAY WARM ENOUGH TO KEEP FREEZING RAIN OUT OF THE
FCST. VIS/CIG CONDS SHOULD FALL INTO THE MVFR RANGE AT ALL SITES
THROUGH 15Z WITH PREVAILING IFR CIGS EXPECTED TO DEVELOP AS WINDS
BECOME NNE AND EVENTUALLY NW AFTER 18Z. THERE COULD ALSO BE A PERIOD
OF IFR VIS CONDS ESPECIALLY AT LAF WHERE SOME FROZEN PRECIP/SNOW
COULD DEVELOP AFTER 15Z.
THE BULK OF PRECIP SHOULD BE ENDING BY 00Z WITH SCT SNOW SHOWERS
EXPECTED BUT THEY SHOULD BE THE EXCEPTION AND NOT THE RULE. CIGS MAY
SHOW A VERY GRADUAL RISE FROM IFR INTO THE MVFR RANGE AFTER 00Z.
&&
.DISCUSSION...
LOW PRESSURE CENTER IS CURRENTLY OVR ST LOUIS. GREATEST PRESSURE
FALLS ARE SE OF THERE SO EXPECT LOW TO MOVE SE TO THE OH RVR.
CURRENTLY ISENTROPIC FORCING IS CAUSING MAINLY RAIN ACRS THE FA
/FZRA AT MIE/ AS SEEN ON THE RADAR MOSAIC. FRONTOGENETICAL FORCING
IS CAUSING SNOW BANDS TO THE N ACRS THE NRN BORDER OF INDIANA.
AIRCRAFT SOUNDING SHOWED A WARM LAYER OF A COUPLE HUNDRED MB THAT
GETS UP TO 4C. TEMPS IN THE FA WERE IN THE UPR 20S AT MIE TO LOW 40S
AT LWV. DEWPTS ARE IN THE MID 20S TO MID 30S. WINDS ARE ENE AT
AROUND 5 KTS.
FORECAST FOCUS IS ON PTYPE TODAY AND POTENTIAL CHANGEOVER. MODELS IN
GOOD AGREEMENT SO WL USE A BLEND UNLESS NOTED. GUIDANCE NUMBERS
SIMILAR SO BLENDED THEM AS WELL.
TODAY...MODELS ARE RUNNING COLDER THAN OBS AT SFC . SNDINGS ARE ALSO
WARMER ALOFT THIS RUN THAN PREVIOUS AND THIS IS RESULTING IN RAIN
EXTENDING FURTHER N THAN PREVIOUSLY EXPECTED. WITH NELY/ELY WINDS
AND PRECIPITATION DO NOT EXPECT MUCH WARMING TODAY. TEMPS SHUD BE
PRETTY STEADY UNTIL THE COLD FNT COMES THRU LATE TODAY. AS A RESULT
DECIDED TO SHIFT PTYPES NORTH. AS A RESULT WL DROP ADVISORY FOR
SOUTHERN COUNTIES. LOOKING AT RADAR ECHOES AND OBS UPSTREAM...DO NOT
EXPECT TO SEE SNOW ANYWHERE BEFORE 18Z AND FROM 18-0Z FORCING IS
STARTING TO WANE. THUS CUT SNOWFALL AMOUNTS QUITE A BIT AS WELL.
STILL KEEPING ADVISORY APPROX NORTH OF I70 AS A
SLEET/FZRA/EVENTUALLY SNOW MIX IS STILL EXPECTED TODAY.
TONIGHT KEEP A CHC UP IN THE NE FOR SOME WRAPAROUND AS SYSTEM MOVES
NE INTO OHIO.
SUN AND SUN NT KEPT FCST DRY AS WEAK HI PRES ARRIVES. MON POPS START
AS NEXT SYSTEM APPROACHES. SOME DISAGREEMENT IN NAM/ECMWF/GFS AS TO
WHEN POPS SHUD BE IN/OUT. THUS WILL KEEP POPS IN THE CHC CATEGORY
NOW AS CONFIDENCE ON TIMING ISN/T HIGH. CURRENTLY LOOKS LIKE
SOMETIME MON AFTERNOON AND INTO TUE. H8 TEMPS STAY BLO FREEZING FOR
MOST OF THE AREA SO WENT WITH SNOW. IN THE S FROM 18Z MON-0Z TUE
LEFT A RAIN/SNOW MIX IN BASED ON HIGHS GETTING A FEW DEGREES ABOVE
FREEZING.
NO BIG CHANGES IN THE EXTENDED. A FEW TWEAKS OF TEMPS FOR
COLLABORATION.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 7 PM EST SATURDAY
FOR NORTH OF INTERSTATE 70.
&&
$$
AVIATION...CO
PUBLIC....CP
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
336 AM EST SAT JAN 10 2009
.DISCUSSION...
LOW PRESSURE CENTER IS CURRENTLY OVR ST LOUIS. GREATEST PRESSURE
FALLS ARE SE OF THERE SO EXPECT LOW TO MOVE SE TO THE OH RVR.
CURRENTLY ISENTROPIC FORCING IS CAUSING MAINLY RAIN ACRS THE FA
/FZRA AT MIE/ AS SEEN ON THE RADAR MOSAIC. FRONTOGENETICAL FORCING
IS CAUSING SNOW BANDS TO THE N ACRS THE NRN BORDER OF INDIANA.
AIRCRAFT SOUNDING SHOWED A WARM LAYER OF A COUPLE HUNDRED MB THAT
GETS UP TO 4C. TEMPS IN THE FA WERE IN THE UPR 20S AT MIE TO LOW 40S
AT LWV. DEWPTS ARE IN THE MID 20S TO MID 30S. WINDS ARE ENE AT
AROUND 5 KTS.
FORECAST FOCUS IS ON PTYPE TODAY AND POTENTIAL CHANGEOVER. MODELS IN
GOOD AGREEMENT SO WL USE A BLEND UNLESS NOTED. GUIDANCE NUMBERS
SIMILAR SO BLENDED THEM AS WELL.
TODAY...MODELS ARE RUNNING COLDER THAN OBS AT SFC . SNDINGS ARE ALSO
WARMER ALOFT THIS RUN THAN PREVIOUS AND THIS IS RESULTING IN RAIN
EXTENDING FURTHER N THAN PREVIOUSLY EXPECTED. WITH NELY/ELY WINDS
AND PRECIPITATION DO NOT EXPECT MUCH WARMING TODAY. TEMPS SHUD BE
PRETTY STEADY UNTIL THE COLD FNT COMES THRU LATE TODAY. AS A RESULT
DECIDED TO SHIFT PTYPES NORTH. AS A RESULT WL DROP ADVISORY FOR
SOUTHERN COUNTIES. LOOKING AT RADAR ECHOES AND OBS UPSTREAM...DO NOT
EXPECT TO SEE SNOW ANYWHERE BEFORE 18Z AND FROM 18-0Z FORCING IS
STARTING TO WANE. THUS CUT SNOWFALL AMOUNTS QUITE A BIT AS WELL.
STILL KEEPING ADVISORY APPROX NORTH OF I70 AS A
SLEET/FZRA/EVENTUALLY SNOW MIX IS STILL EXPECTED TODAY.
TONIGHT KEEP A CHC UP IN THE NE FOR SOME WRAPAROUND AS SYSTEM MOVES
NE INTO OHIO.
SUN AND SUN NT KEPT FCST DRY AS WEAK HI PRES ARRIVES. MON POPS START
AS NEXT SYSTEM APPROACHES. SOME DISAGREEMENT IN NAM/ECMWF/GFS AS TO
WHEN POPS SHUD BE IN/OUT. THUS WILL KEEP POPS IN THE CHC CATEGORY
NOW AS CONFIDENCE ON TIMING ISN/T HIGH. CURRENTLY LOOKS LIKE
SOMETIME MON AFTERNOON AND INTO TUE. H8 TEMPS STAY BLO FREEZING FOR
MOST OF THE AREA SO WENT WITH SNOW. IN THE S FROM 18Z MON-0Z TUE
LEFT A RAIN/SNOW MIX IN BASED ON HIGHS GETTING A FEW DEGREES ABOVE
FREEZING.
NO BIG CHANGES IN THE EXTENDED. A FEW TWEAKS OF TEMPS FOR
COLLABORATION.
&&
.AVIATION...DISCUSSION FOR THE 06Z TAFS
MAIN PROBLEM FOR AVIATION WILL BE THE MIXED WINTER PRECIPITATION
MOVING THROUGH AREA. TAFS WILL START OUT WITH A STATIONARY FRONT
ACROSS CENTRAL INDIANA. SHOWERS WITH A FEW THUNDERSHOWERS QUICKLY
DEVELOPED OVER EASTERN IL BETWEEN 0330Z-0430Z. CONDITIONS ARE
RUNNING SLIGHTLY WARMER THEN PREVIOUS FORECAST. FOR THE IND AREA
THIS WOULD GIVE INITIALLY RAIN. THE PCPN SHOULD CAUSE SOME
EVAPORATIVE COOLING. THIS WILL THEN GIVE A MIXTURE OF FZRA AND
SLEET. PCPN SHOULD CHANGE TO A MIXTURE OF FZRA AND SLEET BY 10Z. THE
HUF AREA SHOULD HAVE RA CHANGING OVER TO FZRA AND SLEET AROUND 10Z.
JUST RAIN OVERNIGHT IN THE BMG AREA WITH SLEET IN LAF. CONDITIONS
WILL DECREASE TO IFR IN ALL TAF LOCATIONS BY 10Z. THE COLD FRONT
WILL SWEEP THROUGH INDIANA SATURDAY MORNING. THIS WILL QUICKLY
CHANGE THE MIXED PCPN TO SNOW. AS THE FRONT PULLS AWAY FROM INDIANA
CONDITIONS SHOULD INCREASE TO MVFR AFTER 20Z. DRIER AIR WILL MOVE IN
AFTER 01Z ENDING THE PCPN BUT MVFR CIGS WILL REMAIN.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 7 PM EST SATURDAY
FOR NORTH OF INTERSTATE 70.
&&
$$
AVIATION...SH
PUBLIC....CP
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
631 AM EST SAT JAN 10 2009
UPDATED AVIATION DISCUSSION FOR 12Z TAF ISSUANCE
.SYNOPSIS...
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW RELATIVELY LO
AMPLITUDE...DRY WNW FLOW ALF BTWN RDGING OVER THE W COAST AND
TROFFING IN SE CAN (00Z PWAT IS 0.14 INCH AT BOTH INL/YPL). BUT
AIRMASS OVER LK SUP IN LGT NW FLOW E OF HI PRES RDG IN NRN MN IS
SUFFICIENTLY COLD (00Z H85 TEMP AT APX WAS -15C) TO GENERATE LK CLD
AND SOME LES. SHARP INVRN SHOWN ARND H875 ON 02Z TAMDAR SDNG FM SAW
AND ACYC/RELATIVELY LGT WIND REGIME EXTENDING E FM THE RDG IN MN
APPEARS TO BE LIMITING INTENSITY OF THE SHSN...ESPECIALLY OVER THE W
CLOSER TO EVEN LOWER INVRN NR H925 AS SHOWN ON 00Z INL RAOB. THE LES
IS A BIT MORE SGNFT OVER THE E WHERE CONFLUENCE BTWN LGT LAND BREEZE
ELY WIND OFF ONTARIO AND GENERAL NNW SYNOPTIC SCALE FLOW MAY BE
ENHANCING CNVGC. 02Z REPORT FM TWO HEART ALONG THE SHORE IN LUCE
COUNTY INDICATED 4 INCHES/PAST 2 HRS. CLOSEST CNDN MONTREAL RIVER
RADAR SUGS BAND THAT MAY HAVE BEEN RESPONSIBLE IS NOW OFFSHORE AND
WEAKER. MQT 88D SHOWS AN AREA OF LES IMPACTING ALGER COUNTY WITH
JUST A FEW REFLECTIVITY RETURNS ABV 20DBZ. TO THE S...RATHER STRONG
BUT POSITIVELY TILTED SHRTWV OVER NB IS SUPPORTING AN AREA OF SN
THAT IS TRACKING WELL S OF THE FA. SOME HI CLDS ON THE NRN FRINGE OF
THIS SYS ARE BRUSHING THE SRN TIER. TEMPS OVER THE INTERIOR W HAVE
ALREADY FALLEN WELL BLO ZERO WITH MOCLR SKIES/LGT WINDS CLOSER TO HI
PRES IN MN. TO THE NW...THERE IS A BAND OF HI BASED SC/LO AC
STRETCHING FM NW ONTARIO SWWD INTO THE NRN PLAINS ASSOCIATED WITH
MSTR SHOWN BTWN H85-65 ON THE 00Z BIS RAOB. THIS CLD BAND IS
SHIFTING SEWD IN THE WNW H7 FLOW. WL TEND TOWARD THE LOWER END OF
MOS GUIDANCE FOR HI TEMPS PER UPSTREAM OBS ON FRI/RELATIVELY HI
STABILITY OF AIRMASS IN PLACE.
&&
.DISCUSSION...
MAIN FCST CONCERNS IN THE SHORT TERM ARE LES TRENDS/AMTS. FOCUS FOR
LATER IN THE WEEKEND INTO MON REVOLVES ARND TIMING/IMPACT OF SHRTWVS
TOPPING WRN RDG THAT ARE FCST TO MOVE ACRS THE UPR GRT LKS.
FOR TDAY...HI PRES RDG CENTER OVER MN IS FCST TO SINK SLOWLY SWD
INTO THE CNTRL PLAINS BY 00Z SUN...WITH RDG AXIS EXTENDING NEWD
TOWARD UPR MI. ALTHOUGH LGT NW FLOW ON NE FLANK OF THE RDG AXIS WL
CONTINUE SOME LES...GENERAL DIFFLUENT/ACYC NATURE OF THIS FLOW OVER
UPR MI WL TEND TO LIMIT INTENSITY FOR THE MOST PART. THIS WL BE
ESPECIALLY TRUE OVER THE W...WHICH WL REMAIN CLOSER TO THE RDG/HIER
MSLP/LOWER INVRN ARND 3K FT (HIER H85 TEMPS ARND -11C). BUT ELECTED
TO BUMP UP POPS A BIT OVER THE E NEAR LK SUP TO REFLECT FCST LOWER
H85 TEMPS ARND -14C THRU 00Z SUN THAT INDICATE INVRN BASE WL REMAIN
ARND 4K FT AS SHOWN ON FCST SDNG FM 00Z LOCAL WRF-ARW RUN FOR GRAND
MARAIS. CONTINUED LLVL CNVGC BTWN SYNOPTIC SCALE NW FLOW/LGT ELY
FLOW OFF SE ONTARIO ALSO INCREASES CONFIDENCE THAT POPS WL BE HIER.
AS H925 FLOW BEGINS TO BACK LATER IN THE DAY TO MORE W...A SMALLER
AND SMALLER AREA CLOSER TO THE SHORE WL BE IMPACTED BY THE SHSN.
OVER THE SRN TIER...EXPECT A DECENT AMT OF SUNSHINE WITH RDG AXIS
DOMINATING. OTRW...EXPECT BAND OF CLD NOW MOVING SEWD TOWARD THE UPR
GRT LKS FM THE NRN PLAINS/NW ONTARIO TO GRDLY DSPT AS IT MOVES INTO
RDG AXIS OVER WRN UPR MI TOWARD 00Z SUN. VARIOUS MODEL FCST H85-7 RH
FIELDS SHOW DCRSG RH WITHIN THE BAND AS IT SHIFTS TO THE SE.
FOR TNGT...FIRST DISTURBANCE TRACKING OVER WRN RDG IS PROGGED TO
APRCH AND MOVE INTO WI AFT 06Z. AS THIS DISTURBANCE APRCHS...THE
LLVL FLOW WL BCM MORE WSW OVER THE E AND LIFT LINGERING SHSN
IMPACTING THE E NR THE SHORE OUT OVER THE OPEN WATERS OF ERN LK SUP.
THE INTERACTION BTWN THE ASSOCIATED DPVA/H85-5 QVECTOR CNVGC AND
FVRBL WLY FLOW SHOULD INCRS SHSN CHCS OVER THE KEWEENAW...BUT MOS
POPS FOR CMX ARE ON THE LO SIDE (GFS MOS IS HIEST WITH A POP OF 35).
GFS/NAM ARE ALSO RELUCTANT TO MOISTEN A LYR CENTERED ARND H85 THRU
12Z SUN AS SHOWN ON FCST SDNGS...PROBABLY DUE TO NEGLIGIBLE
ISENTROPIC LIFT AHEAD OF THE SHRTWV. SO OPTED TO CUT GOING LIKELY
POPS A BIT TO JUST HI CHC OVER THE KEWEENAW. OTHER LOCATIONS SHOULD
REMAIN DRY THRU 12Z WITH NO OPPORTUNITY FOR LK MOISTENING. OTRW...
GENERAL INCRS IN MID/HI CLD ASSOCIATED WITH SHRTWV MAY TEND TO LIMIT
DIURNAL TEMP FALL...BUT LGT WINDS ASSOCIATED WITH RDG AXIS PASSING
TO THE S SUGS TEMPS WL FALL BLO MOS GUIDANCE.
ALTHOUGH DYNAMICS/DEEP MSTR ASSOCIATED WITH DEPARTING SHRTWV THRU
THE LOWER GRT LKS WL EXIT ON SUN...CAD IN ITS WAKE BEST SHOWN BY THE
00Z GFS/12Z ECMWF MODELS WL SUPPORT INCRSG POPS FOR LES OVER
ESPECIALLY THE WRN ZNS IN THE MRNG AND THEN OVER THE E IN THE AFTN
AS LLVL FLOW VEERS NW AS H85 TEMPS FALL TOWARD -15C BY 00Z MON. THE
LES WL TEND TO DIMINISH ON SUN NGT WITH ARRIVAL OF SHRTWV RDGING/
SFC HI PRES RDG AFT 06Z. WITH PARTIAL CLRG OVER THE SRN TIER...
EXPECT TEMPS TO FALL BLO EVEN THE LOWER GFS MOS GUIDANCE EVEN IF
THERE IS AN INCRS IN HI CLD LATE IN ADVANCE OF NEXT SHRTWV.
NEXT SHRTWV/ACCOMPANYING CLIPPER LO THAT WL USHER IN COLDEST AIRMASS
OF THE SEASON WL DIVE SE THRU THE UPR MIDWEST ON MON. ACTUALLY...
THERE WL BE TWO SHRTWVS THAT IMPACT THE FA...SO PREFER TO TEND AWAY
FM THE DEEPER SOLN FOR THE LO SHOWN BY THE 00Z GFS AND LEAN TOWARD
THE NAM/ECMWF/CNDN. THE FIRST OF THESE AND THE LO TRACK FAIRLY FAR
TO THE S WITH JUST AN INVERTED TROF TO ITS NE IMPACTING UPR MI.
STRONG COLD FNT ASSOCIATED WITH THE SECOND SHRTWV WL PLOW INTO UPR
MI DURING THE AFTN. BUMPED UP POPS TO HI LIKELY OVER THE NCNTRL AND
W WITH UPSLOPE NLY FLOW DVLPG IN THE AFTN BEHIND THE FNT. SHARP FNTL
ZN/H85-7 FGEN SHIFTING ACRS THE FA WARRANTS HIER POPS EVEN OVER THE
SCNTRL DESPITE A GENERAL DEARTH OF MSTR (ABOUT 1G/KG SPECIFIC
HUMIDITY AT H7 WITH PWAT NOT MUCH MORE THAN 0.25 INCH). ONCE THE
COLD FNT SHIFTS TO THE S ON MON NGT...PCPN WL TREND TOWARD PURE LES
AND END OVER THE SCNTRL. INCLUDED MENTION OF BLSN WITH GUSTY N WINDS
BEHIND THE FNT MON AFTN INTO TUE BLOWING INCRSGLY FINE SN FLAKES
WITH DGZ SINKING INTO THE GRND ON TUE. WITH EVEN THE SOMEWHAT MORE
CONSERVATIVE 00Z ECMWF SHOWING H85 TEMPS SINKING AS LO AS -26C OVER
THE W BY 12Z TUE...WL REISSUE SPS TO HIGHLIGHT IMPENDING COLD.
&&
.AVIATION (FOR THE 12Z TAF ISSUANCE)...
AT KCMX...A WEST FLOW ABOVE THE SURFACE WILL KEEP MVFR LAKE EFFECT
CLOUDS IN PLACE THROUGH MUCH OF THE FORECAST. HOWEVER...A PERIOD
DURING THE EVENING WHERE THE CLOUDS SCATTER OUT IS POSSIBLE...DUE TO
THE FLOW BACKING SOUTHWEST BRIEFLY. LIGHT SNOW SHOWERS SHOULD
CONTINUE AS WELL...MOSTLY VFR VSBY VARIETY...EXCEPT EARLY IN THE
FORECAST WHERE MVFR VSBYS ARE EXPECTED.
AT KSAW...DRY AIR IN PLACE AND A WESTERLY WIND FLOW COMING OFF LAND
SHOULD HELP TO MAINTAIN VFR CONDITIONS THROUGH THE NEXT 24 HOURS.
&&
.MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)...
STRONGEST WINDS DURING THE FCST PERIOD STILL LOOK TO OCCUR MON
AFTN/NIGHT IN THE WAKE OF AN ARCTIC FRONT...WITH NORTH TO NW GALES
TO 35 KT OVER NORTH CENTRAL AND EASTERN SUPERIOR. DUE TO THE COLD
AIR RUSHING IN BEHIND THE FRONT AND BUILDING WAVES...HEAVY FREEZING
SPRAY IS EXPECTED AS WELL. HEAVY FREEZING SPRAY WILL CONTINUE
THROUGH THE END OF THE FORECAST...DUE TO THE ARCTIC AIR SITTING OVER
LAKE SUPERIOR AND GENERAL BLUSTERY CONDITIONS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...NONE.
LAKE SUPERIOR...NONE.
LAKE MICHIGAN...NONE.
&&
$$
SYNOPSIS/DISCUSSION...KC
AVIATION...AJ
MARINE...AJ
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
415 AM EST SAT JAN 10 2009
.SYNOPSIS...
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW RELATIVELY LO
AMPLITUDE...DRY WNW FLOW ALF BTWN RDGING OVER THE W COAST AND
TROFFING IN SE CAN (00Z PWAT IS 0.14 INCH AT BOTH INL/YPL). BUT
AIRMASS OVER LK SUP IN LGT NW FLOW E OF HI PRES RDG IN NRN MN IS
SUFFICIENTLY COLD (00Z H85 TEMP AT APX WAS -15C) TO GENERATE LK CLD
AND SOME LES. SHARP INVRN SHOWN ARND H875 ON 02Z TAMDAR SDNG FM SAW
AND ACYC/RELATIVELY LGT WIND REGIME EXTENDING E FM THE RDG IN MN
APPEARS TO BE LIMITING INTENSITY OF THE SHSN...ESPECIALLY OVER THE W
CLOSER TO EVEN LOWER INVRN NR H925 AS SHOWN ON 00Z INL RAOB. THE LES
IS A BIT MORE SGNFT OVER THE E WHERE CONFLUENCE BTWN LGT LAND BREEZE
ELY WIND OFF ONTARIO AND GENERAL NNW SYNOPTIC SCALE FLOW MAY BE
ENHANCING CNVGC. 02Z REPORT FM TWO HEART ALONG THE SHORE IN LUCE
COUNTY INDICATED 4 INCHES/PAST 2 HRS. CLOSEST CNDN MONTREAL RIVER
RADAR SUGS BAND THAT MAY HAVE BEEN RESPONSIBLE IS NOW OFFSHORE AND
WEAKER. MQT 88D SHOWS AN AREA OF LES IMPACTING ALGER COUNTY WITH
JUST A FEW REFLECTIVITY RETURNS ABV 20DBZ. TO THE S...RATHER STRONG
BUT POSITIVELY TILTED SHRTWV OVER NB IS SUPPORTING AN AREA OF SN
THAT IS TRACKING WELL S OF THE FA. SOME HI CLDS ON THE NRN FRINGE OF
THIS SYS ARE BRUSHING THE SRN TIER. TEMPS OVER THE INTERIOR W HAVE
ALREADY FALLEN WELL BLO ZERO WITH MOCLR SKIES/LGT WINDS CLOSER TO HI
PRES IN MN. TO THE NW...THERE IS A BAND OF HI BASED SC/LO AC
STRETCHING FM NW ONTARIO SWWD INTO THE NRN PLAINS ASSOCIATED WITH
MSTR SHOWN BTWN H85-65 ON THE 00Z BIS RAOB. THIS CLD BAND IS
SHIFTING SEWD IN THE WNW H7 FLOW. WL TEND TOWARD THE LOWER END OF
MOS GUIDANCE FOR HI TEMPS PER UPSTREAM OBS ON FRI/RELATIVELY HI
STABILITY OF AIRMASS IN PLACE.
&&
.DISCUSSION...
MAIN FCST CONCERNS IN THE SHORT TERM ARE LES TRENDS/AMTS. FOCUS FOR
LATER IN THE WEEKEND INTO MON REVOLVES ARND TIMING/IMPACT OF SHRTWVS
TOPPING WRN RDG THAT ARE FCST TO MOVE ACRS THE UPR GRT LKS.
FOR TDAY...HI PRES RDG CENTER OVER MN IS FCST TO SINK SLOWLY SWD
INTO THE CNTRL PLAINS BY 00Z SUN...WITH RDG AXIS EXTENDING NEWD
TOWARD UPR MI. ALTHOUGH LGT NW FLOW ON NE FLANK OF THE RDG AXIS WL
CONTINUE SOME LES...GENERAL DIFFLUENT/ACYC NATURE OF THIS FLOW OVER
UPR MI WL TEND TO LIMIT INTENSITY FOR THE MOST PART. THIS WL BE
ESPECIALLY TRUE OVER THE W...WHICH WL REMAIN CLOSER TO THE RDG/HIER
MSLP/LOWER INVRN ARND 3K FT (HIER H85 TEMPS ARND -11C). BUT ELECTED
TO BUMP UP POPS A BIT OVER THE E NEAR LK SUP TO REFLECT FCST LOWER
H85 TEMPS ARND -14C THRU 00Z SUN THAT INDICATE INVRN BASE WL REMAIN
ARND 4K FT AS SHOWN ON FCST SDNG FM 00Z LOCAL WRF-ARW RUN FOR GRAND
MARAIS. CONTINUED LLVL CNVGC BTWN SYNOPTIC SCALE NW FLOW/LGT ELY
FLOW OFF SE ONTARIO ALSO INCREASES CONFIDENCE THAT POPS WL BE HIER.
AS H925 FLOW BEGINS TO BACK LATER IN THE DAY TO MORE W...A SMALLER
AND SMALLER AREA CLOSER TO THE SHORE WL BE IMPACTED BY THE SHSN.
OVER THE SRN TIER...EXPECT A DECENT AMT OF SUNSHINE WITH RDG AXIS
DOMINATING. OTRW...EXPECT BAND OF CLD NOW MOVING SEWD TOWARD THE UPR
GRT LKS FM THE NRN PLAINS/NW ONTARIO TO GRDLY DSPT AS IT MOVES INTO
RDG AXIS OVER WRN UPR MI TOWARD 00Z SUN. VARIOUS MODEL FCST H85-7 RH
FIELDS SHOW DCRSG RH WITHIN THE BAND AS IT SHIFTS TO THE SE.
FOR TNGT...FIRST DISTURBANCE TRACKING OVER WRN RDG IS PROGGED TO
APRCH AND MOVE INTO WI AFT 06Z. AS THIS DISTURBANCE APRCHS...THE
LLVL FLOW WL BCM MORE WSW OVER THE E AND LIFT LINGERING SHSN
IMPACTING THE E NR THE SHORE OUT OVER THE OPEN WATERS OF ERN LK SUP.
THE INTERACTION BTWN THE ASSOCIATED DPVA/H85-5 QVECTOR CNVGC AND
FVRBL WLY FLOW SHOULD INCRS SHSN CHCS OVER THE KEWEENAW...BUT MOS
POPS FOR CMX ARE ON THE LO SIDE (GFS MOS IS HIEST WITH A POP OF 35).
GFS/NAM ARE ALSO RELUCTANT TO MOISTEN A LYR CENTERED ARND H85 THRU
12Z SUN AS SHOWN ON FCST SDNGS...PROBABLY DUE TO NEGLIGIBLE
ISENTROPIC LIFT AHEAD OF THE SHRTWV. SO OPTED TO CUT GOING LIKELY
POPS A BIT TO JUST HI CHC OVER THE KEWEENAW. OTHER LOCATIONS SHOULD
REMAIN DRY THRU 12Z WITH NO OPPORTUNITY FOR LK MOISTENING. OTRW...
GENERAL INCRS IN MID/HI CLD ASSOCIATED WITH SHRTWV MAY TEND TO LIMIT
DIURNAL TEMP FALL...BUT LGT WINDS ASSOCIATED WITH RDG AXIS PASSING
TO THE S SUGS TEMPS WL FALL BLO MOS GUIDANCE.
ALTHOUGH DYNAMICS/DEEP MSTR ASSOCIATED WITH DEPARTING SHRTWV THRU
THE LOWER GRT LKS WL EXIT ON SUN...CAD IN ITS WAKE BEST SHOWN BY THE
00Z GFS/12Z ECMWF MODELS WL SUPPORT INCRSG POPS FOR LES OVER
ESPECIALLY THE WRN ZNS IN THE MRNG AND THEN OVER THE E IN THE AFTN
AS LLVL FLOW VEERS NW AS H85 TEMPS FALL TOWARD -15C BY 00Z MON. THE
LES WL TEND TO DIMINISH ON SUN NGT WITH ARRIVAL OF SHRTWV RDGING/
SFC HI PRES RDG AFT 06Z. WITH PARTIAL CLRG OVER THE SRN TIER...
EXPECT TEMPS TO FALL BLO EVEN THE LOWER GFS MOS GUIDANCE EVEN IF
THERE IS AN INCRS IN HI CLD LATE IN ADVANCE OF NEXT SHRTWV.
NEXT SHRTWV/ACCOMPANYING CLIPPER LO THAT WL USHER IN COLDEST AIRMASS
OF THE SEASON WL DIVE SE THRU THE UPR MIDWEST ON MON. ACTUALLY...
THERE WL BE TWO SHRTWVS THAT IMPACT THE FA...SO PREFER TO TEND AWAY
FM THE DEEPER SOLN FOR THE LO SHOWN BY THE 00Z GFS AND LEAN TOWARD
THE NAM/ECMWF/CNDN. THE FIRST OF THESE AND THE LO TRACK FAIRLY FAR
TO THE S WITH JUST AN INVERTED TROF TO ITS NE IMPACTING UPR MI.
STRONG COLD FNT ASSOCIATED WITH THE SECOND SHRTWV WL PLOW INTO UPR
MI DURING THE AFTN. BUMPED UP POPS TO HI LIKELY OVER THE NCNTRL AND
W WITH UPSLOPE NLY FLOW DVLPG IN THE AFTN BEHIND THE FNT. SHARP FNTL
ZN/H85-7 FGEN SHIFTING ACRS THE FA WARRANTS HIER POPS EVEN OVER THE
SCNTRL DESPITE A GENERAL DEARTH OF MSTR (ABOUT 1G/KG SPECIFIC
HUMIDITY AT H7 WITH PWAT NOT MUCH MORE THAN 0.25 INCH). ONCE THE
COLD FNT SHIFTS TO THE S ON MON NGT...PCPN WL TREND TOWARD PURE LES
AND END OVER THE SCNTRL. INCLUDED MENTION OF BLSN WITH GUSTY N WINDS
BEHIND THE FNT MON AFTN INTO TUE BLOWING INCRSGLY FINE SN FLAKES
WITH DGZ SINKING INTO THE GRND ON TUE. WITH EVEN THE SOMEWHAT MORE
CONSERVATIVE 00Z ECMWF SHOWING H85 TEMPS SINKING AS LO AS -26C OVER
THE W BY 12Z TUE...WL REISSUE SPS TO HIGHLIGHT IMPENDING COLD.
&&
.AVIATION (FOR THE 06Z TAF ISSUANCE)...
AT KCMX...MVFR LAKE EFFECT CLOUDS WITH A FEW SNOW SHOWERS ARE
POSSIBLE INTO THE AFTERNOON DUE TO A WEST FLOW OFF LAKE SUPERIOR. A
BRIEF PERIOD OF MVFR VIS WITH THE SNOW SHOWERS IS NOT OUT OF THE
QUESTION EARLY THIS MORNING. FOR THIS EVENING...WINDS ARE EXPECTED
TO BACK TO THE SW...PUSHING THE LAKE EFFECT OUT OF CMX AND THEREFORE
ALLOWING CIGS TO CLIMB TO VFR.
AT KSAW...LAKE EFFECT COMING OFF EASTERN LAKE SUPERIOR MAY BRUSH THE
SITE EARLY...THEN SHIFT TO THE NORTHEAST AS WINDS BACK. VFR
CONDITIONS WILL THEN PERSIST THROUGH THE REST OF THE FORECAST PERIOD
WITH DRY AIR IN PLACE.
&&
.MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)...
STRONGEST WINDS DURING THE FCST PERIOD STILL LOOK TO OCCUR MON
AFTN/NIGHT IN THE WAKE OF AN ARCTIC FRONT...WITH NORTH TO NW GALES
TO 35 KT OVER NORTH CENTRAL AND EASTERN SUPERIOR. DUE TO THE COLD
AIR RUSHING IN BEHIND THE FRONT AND BUILDING WAVES...HEAVY FREEZING
SPRAY IS EXPECTED AS WELL. HEAVY FREEZING SPRAY WILL CONTINUE
THROUGH THE END OF THE FORECAST...DUE TO THE ARCTIC AIR SITTING OVER
LAKE SUPERIOR AND GENERAL BLUSTERY CONDITIONS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...NONE.
LAKE SUPERIOR...NONE.
LAKE MICHIGAN...NONE.
&&
$$
SYNOPSIS/DISCUSSION...KC
AVIATION...AJ
MARINE...AJ
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1237 AM EST SAT JAN 10 2009
UPDATED AVIATION DISCUSSION FOR 06Z TAF ISSUANCE
.SYNOPSIS...
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW NW FLOW ACROSS THE UPPER
GREAT LAKES. SHORTWAVES WERE OVER THE DAKOTAS AND SRN ROCKIES.
CLOSER TO HOME...SFC HIGH PRES EXTENDS FROM SRN MANITOBA ACROSS THE
UPPER LAKES. ALTHOUGH MORNING TAMDAR SOUNDINGS FROM KSAW/CYQT SHOWED
850MB TEMPS OF -18C/-22C RESPECTIVELY WITH MOIST LOW-LEVELS
(ESPECIALLY AT CYQT WHERE MOISTURE EXTENDED TO 800MB)...LES HAS
GENERALLY BEEN LIGHT AND DISORGANIZED IN LIGHT WIND REGIME ACROSS
LAKE SUPERIOR UNDER HIGH PRES RIDGE. EVEN WHERE LOCAL ENHANCED
CONVERGENCE HAS OCCURRED DUE TO LAND BREEZES...LES HAS NOT BEEN WELL
ORGANIZED TO PRODUCE HEAVY SNOW. ONLY EXCEPTION APPEARS TO HAVE
BEEN OVER SE LAKE SUPERIOR WHERE MESOLOW WAS CLEARLY EVIDENT ON
MONTREAL RIVER RADAR JUST NW OF WHITEFISH PT THIS MORNING. HEAVIER
SNOW BANDS ASSOCIATED WITH CIRCULATION IMPACTED FAR NRN LUCE COUNTY
BEFORE MESOLOW DISSIPATED...THOUGH NO REPORTS HAVE BEEN RECEIVED.
EARLY THIS AFTN...A SECOND SMALLER MESOLOW MOVED ONSHORE IN THE
VCNTY OF GRAND MARAIS.
&&
.SHORT TERM (TONIGHT THRU SAT AFTN)...
PCPN ASSOCIATED WITH SHORTWAVE OVER THE DAKOTAS WILL PASS WELL S OF
UPPER MI TONIGHT/SAT MORNING. THIS LEAVES LES AS THE ONLY PCPN
ISSUE. AS CENTER OF HIGH PRES SLIPS TOWARD THE CNTRL PLAINS
TONIGHT...LOW-LEVEL WINDS WILL GRADUALLY BACK MORE WNW AND INCREASE
A BIT. HOWEVER...WITH SYNOPTIC SCALE FLOW ANTICYCLONIC...INVERSIONS
FALLING SLIGHTLY TO 3-4KFT AND 850MB TEMPS RISING 2-4C...LES WILL BE
ON THE LIGHT SIDE (INCH OR TWO AT MOST). THERE ARE INDICATIONS THAT
CONVERGENCE WILL INCREASE SOME ROUGHLY BTWN ONTONAGON AND KCMX
(TYPICAL IN THAT AREA FOR LIGHTER WIND REGIMES WHICH ALLOW LAND
BREEZES TO FOCUS CONVERGENCE BETTER). HOWEVER...THAT AREA WILL ALSO
SEE THE MOST WARMING OVERNIGHT WITH 850MB TEMPS RISING TO -12 TO
-13C BY 12Z SAT. TO THE EAST...MAY SEE ANOTHER MESOLOW FORM
SOMEWHERE OVER FAR SE LAKE SUPERIOR AS HINTED AT BY HIGHER
RESOLUTION MODELS. WILL NEED TO KEEP AN EYE ON AREAS FROM ABOUT
GRAND MARAIS EWD FOR POSSIBLE ENHANCEMENT IF LOW DOES FORM. EVEN IF
IT DOES...WOULD NOT EXPECT SIGNIFICANT ACCUMULATIONS GIVEN THE OTHER
NEGATIVE FACTORS PREVIOUSLY MENTIONED. AWAY FROM LES...TEMPS MAY
PLUMMET. HOWEVER...EVEN AWAY FROM LES...WINDS OFF THE SFC LOOK TO
RETAIN ENOUGH COMPONENT OFF LAKE SUPERIOR THAT CLOUD COVER COULD BE
AN ISSUE FOR MUCH OF THE NIGHT. LOWERED MINS SOME FROM PREVIOUS FCST
GIVEN DOWNWARD TREND IN MOS GUIDANCE. IN GENERAL...SHOULD SEE 0 TO
-5F READINGS. HOWEVER...SHOULD IT CLEAR OUT FOR SEVERAL HRS OVER THE
INTERIOR W...TEMPS COULD EASILY DROP TO -10F OR SO.
ON SAT...LOW-LEVEL WINDS WILL CONTINUE TO BACK. LES SHOULD END OVER
ALL BUT THE KEWEENAW AND THE FAR NE PART OF THE FCST AREA FROM ABOUT
GRAND MARAIS EWD. PREVIOUS FCST MAX TEMPS LOOK ON TRACK WITH LATEST
GUIDANCE...SO CHANGES WERE MINIMAL. HIGHS SHOULD TOP OUT A COUPLE OF
DEGREES EITHER SIDE OF 20F.
.LONG TERM (SATURDAY NIGHT THROUGH NEXT FRIDAY)...
UPPER LEVEL PATTERN THIS WEEKEND IS LOW AMPLITUDE WITH GENERAL NW
FLOW ALOFT INTO THE GREAT LAKES. PATTERN CHANGES NEXT WEEK AS RIDGE
BUILDS INTO WRN NORTH AMERICA WHILE TROUGH DEEPENS OVR EASTERN
CANADA INTO THE GREAT LAKES AND MUCH OF THE EASTERN UNITED STATES.
RESULT IS WELL-ADVERTISED COLD STRETCH DEVELOPING BY MIDDLE OF NEXT
WEEK. THOUGH GUIDANCE HAS BACKED AWAY FM THE ABSOLUTELY BITTER COLD
THAT IT WAS SHOWING A FEW DAYS AGO. LIGHT TO MODERATE LK EFFECT WILL
AFFECT THE SHORES OF LK SUPERIOR IN AREAS FAVORED BY NW/N WINDS. AS
COLD AIR SLIDES INTO GREAT LAKES...MAIN STORM TRACK IS SHUNTED WELL
TO THE SOUTH. SO...AWAY FM THE LK EFFECT AREAS...THE COLD IS THE
MAIN STORY.
SATURDAY NIGHT THROUGH SUNDAY...SHORTWAVE CURRENTLY OVR BRITISH
COLUMBIA SLIDES INTO THE NORTHERN PLAINS AND GREAT LAKES. PRIMARY
PV ANOMALY AND DEEP LAYER Q-VECTOR CONVERGENCE MISSES UPR MI TO THE
SOUTH. EXPECT DECENT AMOUNT OF MID-HIGH CLOUD LATER SAT NIGHT WHICH
WILL PROBABLY PUT BREAKS ON TEMPS. SOUNDINGS MORE FAVORABLE FOR SNOW
OVR KEWEENAW AS LINGERING WRLY FLOW/SHALLOW LK EFFECT IS ENHANCED BY
ADDITIONAL MOISTURE WITH THE WAVE AND APPROACHING H85 TROUGH.
INCREASING MOISTURE AND INVERSION HEIGHTS ON SUNDAY RESULT IN HIGHER
POPS ON KEWEENAW IN CONTINUING WRLY FLOW. WIND SHIFT IN AFTN WILL
BRING SOME SNOW SHOWERS INTO THE INTERIOR OF WRN UPR MI.
ATTN SUNDAY NIGHT IS ON LK EFFECT THAT WILL BE ONGOING ACROSS
KEWEENAW AHEAD OF COLD FRONT SINKING SOUTH ACROSS CNTRL CANADA.
CONVERGENT W WINDS AND INCREASING INVERSION HEIGHTS/MOISTURE LATE
SUNDAY NIGHT ALONG WITH COOLING TEMPS IN THE MIXED LAYER SHOULD
RESULT IN LK EFFECT INCREASING TOWARD DAYBREAK. SOME MODERATE SNOW
SEEMS LIKELY DURING THAT TIME. ON INTO MONDAY...THE GFS/ECMWF
INDICATE COLD FRONT MOVES THROUGH THE KEWEENAW AND FAR WRN UPR MI IN
THE MORNING THEN ACROSS THE REST OF UPR MI ON MONDAY AFTN. SHARP
COLD ADVECTION FAVORS GUSTY NORTH WINDS BEHIND THE COLD FRONT WITH
THE MODERATE SNOW ON THE KEWEENAW SPREADING ACROSS MOST OF NRN UPR
MI THROUGH THE DAY.
ONCE THE LK EFFECT DEVELOPS...IT LIKELY WILL NOT QUIT UNTIL THE
FOLLOWING WEEKEND...OR PERHAPS BRIEFLY FOR A TIME IF THE WINDS
BECOME OFFSHORE. BY LATE IN THE WEEK...EXPECT MOSTLY NW WIND AREAS
OVR KEWEENAW AND EAST OF MARQUETTE TO SEE MOST OF THE SNOW AS STRONG
ARCTIC HIGH PRESSURE OF 1050MB SETTLES ACROSS THE CNTRL PORTION OF
THE CONUS LEADING TO NW FLOW ACROSS THE LAKES.
COLD TEMPERATURES WILL BE THE MAIN WEATHER STORY. GFS AND ECMWF ARE
IN DECENT AGREEMENT DEPICTING TWO SEPARATE COLD AIR INTRUSIONS. THE
FIRST COLD AIR SHOT IS BEHIND THE FRONT ON TUESDAY...WITH ANOTHER
SURGE OF COLD AIR FOR THURSDAY FOLLOWING THE PASSAGE OF A WEAK LOW
PRESSURE SYSTEM TO THE SOUTH. 1000-500MB THICKNESSES TUMBLE BLO
500DAM DURING THOSE TIMES WHILE H85 TEMPS FALL TO AROUND -25C.
GRANTED...THIS IS A FAR CRY FM THE -30C H85 TEMPS THE MODELS WERE
SHOWING EARLIER THIS WEEK...BUT STILL EXPECT DAYTIME HIGHS TO ONLY
STRUGGLE INTO THE SINGLE DIGITS ABOVE ZERO WHILE NIGHTTIME LOWS FALL
WELL BELOW ZERO. PORTIONS OF WRN UPR MI STILL LOOK LIKE THEY COULD
STAY BELOW ZERO FOR DAYTIME HIGHS. WITH THE COLD TEMPS WILL ALSO
COME WIND CHILL ISSUES. WILL LIKELY NEED WIND CHILL ADVISORIES AND
MAY EVEN HAVE THE NEED FOR WARNINGS. WILL CONTINUE TO HIGHLIGHT THE
COLD WITH THE SPECIAL WEATHER STATEMENT (SPSMQT).
&&
.AVIATION (FOR THE 06Z TAF ISSUANCE)...
AT KCMX...MVFR LAKE EFFECT CLOUDS WITH A FEW SNOW SHOWERS ARE
POSSIBLE INTO THE AFTERNOON DUE TO A WEST FLOW OFF LAKE SUPERIOR. A
BRIEF PERIOD OF MVFR VIS WITH THE SNOW SHOWERS IS NOT OUT OF THE
QUESTION EARLY THIS MORNING. FOR THIS EVENING...WINDS ARE EXPECTED
TO BACK TO THE SW...PUSHING THE LAKE EFFECT OUT OF CMX AND THEREFORE
ALLOWING CIGS TO CLIMB TO VFR.
AT KSAW...LAKE EFFECT COMING OFF EASTERN LAKE SUPERIOR MAY BRUSH THE
SITE EARLY...THEN SHIFT TO THE NORTHEAST AS WINDS BACK. VFR
CONDITIONS WILL THEN PERSIST THROUGH THE REST OF THE FORECAST PERIOD
WITH DRY AIR IN PLACE.
&&
.MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)...
STRONGEST WINDS DURING THIS FCST PERIOD WILL OCCUR MON AFTN/NIGHT
IN THE WAKE OF ARCTIC FRONT. ALTHOUGH MODEL GUIDANCE HAS TRENDED
DOWN WITH WINDS...INFLUX OF ARCTIC AIR OVER THE WARMER WATERS OF
LAKE SUPERIOR TYPICALLY RESULTS IN SHARPER COLD FRONTS THAN WHAT
MODELS INDICATE. HAVE THUS RETAINED MENTION OF GALES IN THE WAKE OF
THE FRONT MON AFTN/MON NIGHT. HEAVY FREEZING SPRAY WILL ALSO
DEVELOP UNDER INCREASINGLY COLD AIR/GUSTY WINDS/BUILDING WAVES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...NONE.
LAKE SUPERIOR...NONE.
LAKE MICHIGAN...NONE.
&&
$$
SYNOPSIS/SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...AJ
MARINE...ROLFSON
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
950 PM CST SUN JAN 11 2009
.UPDATE...
/950 PM CST SUN JAN 11 2009/
ADJUSTED MIN TEMPS FOR THE OVERNIGHT...WITH MAIN ADJUSTMENT COMING
FOR THE NRN FA...WHERE TEMPS WILL STRUGGLE TO FALL WITH CLOUDS
REMAINING ALL NIGHT...WITH THE LOW CLOUDS MERELY BEING REPLACED
BY A MID DECK. OTHERWISE...FORECAST LOOKS ON TRACK WITH DRY WX FOR
THE REST OF TONIGHT AS A RIDGE PASSES THRU.
TES
&&
.DISCUSSION...
/326 PM CST SUN JAN 11 2009/
THE MAIN WEATHER FEATURES WE HAVE BEEN TALKING ABOUT REMAIN THE
SAME...TWO GOOD ARCTIC SURGES ASSOCIATED WITH DIGG SHORTWAVE TROFS
AND THE ATTENDANT COLD FRONTS...LEADING TO THE DEVELOPMENT OF A
DEEP ERN NOAM UPPER TROF. THE BIGGEST FCST ISSUES ARE THE
TEMPERATURE TRENDS OVER THE NEXT WEEK. WAA TODAY AND HIGH
TEMPERATURES IN THE U30S TO MIDDLE 40S ARE A TESTAMENT TO THE
POSSIBILITIES IN THE TRANSITIONAL PERIOD OF WAA BETWEEN EACH
ARCTIC SURGE. THE FIRST OF THESE IS STILL ON SCHEDULE FOR LATE
MONDAY INTO MONDAY NIGHT. THERE WILL ALOT OF CLOUDS ON MONDAY
AHEAD OF THIS SYSTEM WHICH MAKES TEMPERATURES QUITE TRICKY. IN ALL
I DIDN`T DEVIATE FAR FROM THE PREVIOUS FCST. THERE IS ALSO A FAIR
AMOUNT OF UNCERTAINTY IN THE AMOUNT OF PCPN WITH THIS SYSTEM. THE
GFS IS ITS TYPICALLY ROBUST SELF BLANKETING THE AREA WITH LIGHT
PCPN...WHILE THE MAJORITY OF THE REMAINDER OF THE MODEL GUIDANCE
SUGGESTS THAT THE PCPN WILL COME VIA TWO MECHANISMS. FIRST A WAA
ZONE IMPACTING NE MO AND WEST CENTRAL IL AND THEN A NARROW
PREFRONTAL BAND. THIS SCENARIO SEEMS MORE LOGICAL AND THUS THE
HIGHEST POPS ARE CONFINED TO THE NRN CWA ON MONDAY AND TAPER SWD.
IT APPEARS THAT ENUF COLD AIR WILL REMAIN IN THESE NRN SXNS TO
SUPPORT MAINLY SNOW AND ANYWHERE FROM A DUSTING UP AN INCH. FROM
CENTRAL SECTIONS SWD...THE BNDRY LAYER WARMS SUFFICIENTLY FOR RAIN
OR A MIX. BELIEVE THE MAJORTITY OF THE PCPN WILL BE NEAR EXITING
THE CWA BY EARLY EVENING ON MONDAY NIGHT WITH COLD AIR PLUNGING
SEWD ON STRONG AND GUSTY NW WINDS. HAVE MENTIONED FLURRIES OR A CHC
OF LIGHT SNOW ON MONDAY NIGHT. BITTER COLD DAY STILL EXPECTED ON
TUESDAY AND HAVE KEPT THE HIGHS AOB THE COLDEST MOS. WAA ALREADY
KICKS IN ON TUESDAY NIGHT AS THE HIGH ASSOCIATED WITH ARCTIC SURGE
ONE DEPARTS...AND THIS WAA IS IN FULL SWING ON WEDNESDAY.
TEMPERATURES WED ARE PERHAPS ONE OF THE BIGGEST UNKNOWNS. I HAVE
WARMED THE HIGHS SOME BUT KEPT COOLER THAN THE MAJORITY OF THE
GUIDANCE TRYING TO KEEP SOME CONTINUITY WITH THE PREVIOUS FCST.
THE MAJOR BLAST OF BITTERLY COLD ARCTIC AIR COMES IN LATE WED INTO
WED NIGHT WITH STRONG GUSTY NW WINDS AND FLURRIES AGAIN. COLDEST
PERIOD OF THE WEEK STILL IS ON TRACK FOR THURS AND THURS NIGHT.
SOME TEMPERATURE MODERATION THEN EXPECTED INTO THE WEEKEND.
GLASS
&&
.AVIATION...
/539 PM CST SUN JAN 11 2009/
FOR THE 00Z TAFS...MAIN FCST CONCERN FOR ERLY TAF PD REVOLVES ARND
MVFR CIGS OVR NRN MO INTO WEST CNTRL IL...HV KEPT MVFR DOMINANT
OVR KUIN WITH SCT020 THRU KSTL AND KSUS BEGINNING AFTER 2Z. WL HV
TO MONITOR THE ONSET OF MVFR CIGS OVR THE NEXT FEW HRS...AIRCRAFT
SOUNDINGS OUT OF KSTL ILLUSTRATE SIGNIFICANT DRY AIR AT LOW LVLS
WHILE SATELLITE SHOWS MVFR CIGS SLWLY PROGRESSING SWD AT A SLOW RATE.
ALL ASIDE AT PRESENT TROF EJECTING EWD OVR THE GRT LKS RGN AS A
WEAK RIDGE OF HI PRES ADVECTS WWD OVR THE MID-MS VLY THRU THE EVNG
AND INTO THE MRNG HRS. AS SUCH WNDS SHLD BECOME LGT AND VRB THRU
THE ERLY TAF PD SHIFTING OUT OF THE S-SW THRU THE MIDDAY AND AFTN
HRS AHEAD OF THE ONSET OF A CLIPPER SYSTEM WHICH WL MV THRU THE MS
VLY RGN MONDAY EVNG INTO ERLY TUE. CLDS SHLD BUILD OVR ALL TAF
LOCALES BY MRNG AND LOWER THRU AFTN. FRONTAL PASSAGE THRU THE FCST
AREA IS EXPECTED ERLY THRU KUIN AND KCOU AOA 20Z WITH PASSAGE AOA
22Z FOR KSTL AND KSUS AFTER WHICH WNDS WL SHIFT OUT OF THE NW AND
BECOME GUSTY AT TIMES. THRU THIS PD MVFR CONDITIONS SHLD DOMINATE
FOR KUIN WITH NEAR MVFR CIGS FURTHER SOUTH FOR ALL OTHER TAF
LOCALES. HV KEPT BETTER CHCS FOR -SN FOR KUIN. WL EVALUATE WITH
LATER TAF FCSTS...BIGGEST DIFFICULTIES RESOLVE AROUND HOW WELL LWR
LVL BNDRY LYR WL MOISTEN AND POTENTIAL IMPACT OF DRIER AIR AT UPR
LVLS BEING WRAPPED INTO THE CLIPPER SYSTEM AS IT PASSES THRU THE
FCST AREA.
SIPPRELL
&&
.CLIMATE...
LAST TIME LOW TEMPERATURES DROPPED BELOW ZERO
STL...JAN 5 1999 -5
COU...FEB 16 2007 -1
UIN...DEC 22 2008 -2
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
554 PM CST SUN JAN 11 2009
.DISCUSSION...
/326 PM CST SUN JAN 11 2009/
THE MAIN WEATHER FEATURES WE HAVE BEEN TALKING ABOUT REMAIN THE
SAME...TWO GOOD ARCTIC SURGES ASSOCIATED WITH DIGG SHORTWAVE TROFS
AND THE ATTENDANT COLD FRONTS...LEADING TO THE DEVELOPMENT OF A
DEEP ERN NOAM UPPER TROF. THE BIGGEST FCST ISSUES ARE THE
TEMPERATURE TRENDS OVER THE NEXT WEEK. WAA TODAY AND HIGH
TEMPERATURES IN THE U30S TO MIDDLE 40S ARE A TESTAMENT TO THE
POSSIBILITIES IN THE TRANSITIONAL PERIOD OF WAA BETWEEN EACH
ARCTIC SURGE. THE FIRST OF THESE IS STILL ON SCHEDULE FOR LATE
MONDAY INTO MONDAY NIGHT. THERE WILL ALOT OF CLOUDS ON MONDAY
AHEAD OF THIS SYSTEM WHICH MAKES TEMPERATURES QUITE TRICKY. IN ALL
I DIDN`T DEVIATE FAR FROM THE PREVIOUS FCST. THERE IS ALSO A FAIR
AMOUNT OF UNCERTAINTY IN THE AMOUNT OF PCPN WITH THIS SYSTEM. THE
GFS IS ITS TYPICALLY ROBUST SELF BLANKETING THE AREA WITH LIGHT
PCPN...WHILE THE MAJORITY OF THE REMAINDER OF THE MODEL GUIDANCE
SUGGESTS THAT THE PCPN WILL COME VIA TWO MECHANISMS. FIRST A WAA
ZONE IMPACTING NE MO AND WEST CENTRAL IL AND THEN A NARROW
PREFRONTAL BAND. THIS SCENARIO SEEMS MORE LOGICAL AND THUS THE
HIGHEST POPS ARE CONFINED TO THE NRN CWA ON MONDAY AND TAPER SWD.
IT APPEARS THAT ENUF COLD AIR WILL REMAIN IN THESE NRN SXNS TO
SUPPORT MAINLY SNOW AND ANYWHERE FROM A DUSTING UP AN INCH. FROM
CENTRAL SECTIONS SWD...THE BNDRY LAYER WARMS SUFFICIENTLY FOR RAIN
OR A MIX. BELIEVE THE MAJORTITY OF THE PCPN WILL BE NEAR EXITING
THE CWA BY EARLY EVENING ON MONDAY NIGHT WITH COLD AIR PLUNGING
SEWD ON STRONG AND GUSTY NW WINDS. HAVE MENTIONED FLURRIES OR A CHC
OF LIGHT SNOW ON MONDAY NIGHT. BITTER COLD DAY STILL EXPECTED ON
TUESDAY AND HAVE KEPT THE HIGHS AOB THE COLDEST MOS. WAA ALREADY
KICKS IN ON TUESDAY NIGHT AS THE HIGH ASSOCIATED WITH ARCTIC SURGE
ONE DEPARTS...AND THIS WAA IS IN FULL SWING ON WEDNESDAY.
TEMPERATURES WED ARE PERHAPS ONE OF THE BIGGEST UNKNOWNS. I HAVE
WARMED THE HIGHS SOME BUT KEPT COOLER THAN THE MAJORITY OF THE
GUIDANCE TRYING TO KEEP SOME CONTINUITY WITH THE PREVIOUS FCST.
THE MAJOR BLAST OF BITTERLY COLD ARCTIC AIR COMES IN LATE WED INTO
WED NIGHT WITH STRONG GUSTY NW WINDS AND FLURRIES AGAIN. COLDEST
PERIOD OF THE WEEK STILL IS ON TRACK FOR THURS AND THURS NIGHT.
SOME TEMPERATURE MODERATION THEN EXPECTED INTO THE WEEKEND.
GLASS
&&
.AVIATION...
/539 PM CST SUN JAN 11 2009/
FOR THE 00Z TAFS...MAIN FCST CONCERN FOR ERLY TAF PD REVOLVES ARND
MVFR CIGS OVR NRN MO INTO WEST CNTRL IL...HV KEPT MVFR DOMINANT
OVR KUIN WITH SCT020 THRU KSTL AND KSUS BEGINNING AFTER 2Z. WL HV
TO MONITOR THE ONSET OF MVFR CIGS OVR THE NEXT FEW HRS...AIRCRAFT
SOUNDINGS OUT OF KSTL ILLUSTRATE SIGNIFICANT DRY AIR AT LOW LVLS
WHILE SATELLITE SHOWS MVFR CIGS SLWLY PROGRESSING SWD AT A SLOW RATE.
ALL ASIDE AT PRESENT TROF EJECTING EWD OVR THE GRT LKS RGN AS A
WEAK RIDGE OF HI PRES ADVECTS WWD OVR THE MID-MS VLY THRU THE EVNG
AND INTO THE MRNG HRS. AS SUCH WNDS SHLD BECOME LGT AND VRB THRU
THE ERLY TAF PD SHIFTING OUT OF THE S-SW THRU THE MIDDAY AND AFTN
HRS AHEAD OF THE ONSET OF A CLIPPER SYSTEM WHICH WL MV THRU THE MS
VLY RGN MONDAY EVNG INTO ERLY TUE. CLDS SHLD BUILD OVR ALL TAF
LOCALES BY MRNG AND LOWER THRU AFTN. FRONTAL PASSAGE THRU THE FCST
AREA IS EXPECTED ERLY THRU KUIN AND KCOU AOA 20Z WITH PASSAGE AOA
22Z FOR KSTL AND KSUS AFTER WHICH WNDS WL SHIFT OUT OF THE NW AND
BECOME GUSTY AT TIMES. THRU THIS PD MVFR CONDITIONS SHLD DOMINATE
FOR KUIN WITH NEAR MVFR CIGS FURTHER SOUTH FOR ALL OTHER TAF
LOCALES. HV KEPT BETTER CHCS FOR -SN FOR KUIN. WL EVALUATE WITH
LATER TAF FCSTS...BIGGEST DIFFICULTIES RESOLVE AROUND HOW WELL LWR
LVL BNDRY LYR WL MOISTEN AND POTENTIAL IMPACT OF DRIER AIR AT UPR
LVLS BEING WRAPPED INTO THE CLIPPER SYSTEM AS IT PASSES THRU THE
FCST AREA.
SIPPRELL
&&
.CLIMATE...
LAST TIME LOW TEMPERATURES DROPPED BELOW ZERO
STL...JAN 5 1999 -5
COU...FEB 16 2007 -1
UIN...DEC 22 2008 -2
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
225 PM MST SUN JAN 11 2009
.DISCUSSION...
THE LATEST WATER VAPOR LOOP SHOWS A RIDGE AMPLIFYING OVER THE
EASTERN PACIFIC OCEAN. 400-250MB ACARS WINDS SUPPORT A 120-150 KNOT
NORTHERLY JET ALONG THE EASTERN PERIPHERY OF THE RIDGE OVER THE
NORTHERN ROCKIES...FORCING SEVERAL SHEARED SHORT WAVES SE INTO THE
CENTRAL PLAINS STATES. THE MAIN CHALLENGE IN THIS PATTERN WILL
FOCUS ON TEMPS AS SEVERAL SURFACE FRONTAL BOUNDARIES ADVANCE
SOUTH ACROSS THE EASTERN PLAINS BEHIND EACH DEPARTING SHORT WAVE.
THE 12Z NAM/GFS/ECMWF SHOW THE FIRST BOUNDARY CRASHING SOUTH THRU
THE EASTERN PLAINS MONDAY MORNING WITH SOME LIGHT QPF ALONG AND
BEHIND THE BOUNDARY. RAISED POPS TO JUST ABOVE MENTION FOR SOME
LIGHT SNOW ALONG THE RATON RIDGE EAST TO NORTHERN UNION COUNTY...
HOWEVER ENSEMBLE QPF GREATER THAN 0.01 INCH IS NOT SUPPORTED...
LEADING TO LOW CONFIDENCE. TEMPS MONDAY WILL FALL 5 TO 10F BELOW
TODAYS HIGHS IN THE NE PLAINS. TEMPS REBOUND AGAIN TUESDAY BUT
ONLY BRIEFLY BEFORE THE NEXT WEAK BOUNDARY SINKS SOUTH WEDNESDAY
INTO THURSDAY. THE REMAINDER OF THE AREA WILL EXPERIENCE NEAR NORMAL
TEMPERATURES THROUGH THE PERIOD WITH PATCHY HIGH CLOUDS. GUYER
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL ALL AIRPORTS. NO AVIATION WEATHER
HAZARDS EXPECTED FOR THE NEXT 24 HOURS.
NEXT AVIATION DISCUSSION SCHEDULED FOR 10Z. 52
&&
.FIRE WEATHER...
TRANQUIL WEATHER HAS PREVAILED TODAY ALONG WITH POOR VENTILATION...
AND THIS WILL BE THE RECURRING THEME FOR MOST OF THE WEEK. ANOTHER
NIGHT OF LIGHT TERRAIN DRIVEN WINDS AND VERY STRONG TEMPERATURE
INVERSIONS ARE EXPECTED TONIGHT ALONG AND WEST OF THE CENTRAL
MOUNTAINS. A BACK DOOR COLD FRONT WILL SPILL INTO THE EASTERN
PLAINS BY MIDDAY MONDAY...AND GUSTY WINDS FROM THE NORTH NORTHEAST
WILL OCCUR ALONG WITH A SUBTLE MODERATION TO TEMPERATURES IN THE
NORTHEASTERN PLAINS. A STRAY SHOWER MAY DEVELOP AS THE FRONT
OVERTAKES THE NORTHEAST HIGHLANDS AND PROVIDES A LIGHT UPSLOPE
COMPONENT...BUT NO SIGNIFICANT COVERAGE OR ACCUMULATION IS EXPECTED.
CENTRAL TO WESTERN AREAS WILL CONTINUE TO SEE FAIR TO POOR VENTILATION
CONDITIONS ON MONDAY...TUESDAY...AND WEDNESDAY. ANOTHER BACK DOOR
COLD FRONT WILL APPROACH THE EASTERN PLAINS ON WEDNESDAY...BUT
MODELS ARE STILL KEEPING THE CORE OF THE COLDER AIR MASS FARTHER
EAST WITH THE BOUNDARY JUST GRAZING THE EASTERN ZONES. 52
&&
.PRELIMINARY POINT TEMPS/POPS...
FARMINGTON...................... 15 39 15 41 / 0 0 0 0
GALLUP.......................... 8 40 8 43 / 0 0 0 0
GRANTS.......................... 11 44 13 45 / 0 0 0 0
GLENWOOD........................ 22 61 23 61 / 0 0 0 0
CHAMA........................... 5 40 5 40 / 0 0 0 0
LOS ALAMOS...................... 20 41 19 41 / 0 0 0 0
RED RIVER....................... 3 34 2 38 / 0 0 0 0
TAOS............................ 2 36 4 40 / 0 0 0 0
SANTA FE........................ 18 38 16 40 / 0 0 0 0
SANTA FE AIRPORT................ 19 43 19 44 / 0 0 0 0
ESPANOLA........................ 15 45 15 46 / 0 0 0 0
ALBUQUERQUE HEIGHTS............. 25 48 26 49 / 0 0 0 0
ALBUQUERQUE VALLEY.............. 18 50 20 50 / 0 0 0 0
ALBUQUERQUE FOOTHILLS........... 23 47 24 48 / 0 0 0 0
ALBUQUERQUE WEST MESA........... 19 50 22 50 / 0 0 0 0
SOCORRO......................... 19 53 22 52 / 0 0 0 0
SANDIA PARK/CEDAR CREST......... 17 42 15 42 / 0 0 0 0
MORIARTY/ESTANCIA............... 17 45 16 45 / 0 0 0 0
CARRIZOZO....................... 21 52 22 50 / 0 0 0 0
RUIDOSO......................... 22 50 18 49 / 0 0 0 0
RATON........................... 11 40 9 51 / 0 5 0 0
LAS VEGAS....................... 20 43 16 49 / 0 0 0 0
ROY............................. 22 42 17 52 / 0 0 0 0
CLAYTON......................... 25 41 18 54 / 0 5 0 0
SANTA ROSA...................... 20 52 19 58 / 0 0 0 0
TUCUMCARI....................... 20 49 18 56 / 0 0 0 0
FORT SUMNER..................... 19 55 18 56 / 0 0 0 0
CLOVIS.......................... 23 54 22 55 / 0 0 0 0
PORTALES........................ 19 56 20 56 / 0 0 0 0
ROSWELL......................... 22 62 23 56 / 0 0 0 0
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
GUYER/52
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